Drum unit, cartridge and coupling member

[0001] The present invention relates to a process cartridge usable with an image forming apparatus using an electrophotographic process, or the like.

[0002] In an electrophotographic image forming apparatus, there is known a structure in which elements such as a photosensitive drum and a developing roller, which are rotatable members related to image formation, are integrated into a cartridge which is detachably mountable relative to a main assembly of an image forming apparatus (hereinafter, the apparatus main assembly). In such a structure, a structure for receiving a driving force from the apparatus main assembly to rotate the photosensitive drum in the cartridge is employed in many apparatuses. At this time, a structure is known in which a driving force is transmitted through engagement between a coupling member on a cartridge side and a driving force transmitting portion such as a drive pin on the apparatus main assembly side.

[0003] For example, Japanese Patent Laid-Open No. 2008-233867 discloses a cartridge having a coupling member provided at a end portion of a photosensitive drum so as to be tiltable with respect to a rotation axis of the photosensitive drum.

[0004] It is another object of the present invention to develop the above-mentioned conventional technique.

[0005] Typical structures are as follows.

[0006] A drum unit detachably mountable to a main assembly of an electrophotographic image forming apparatus, the apparatus including a driving shaft provided with a recess, said drum unit comprising:

• • [0007] (I) a photosensitive drum; and
  • [0008] (II) a coupling member provided on said photosensitive drum, said coupling member including,
    • [0009] (II-I) a driving force receiving portion configured to enter the recess and receive a driving force for rotating said photosensitive drum, and
    • [0010] (II-II) a supporting portion movably supporting said driving force receiving portion,
  • [0011] wherein at least a part of said supporting portion and/or at least a part of said driving force receiving portion is disposed inside said photosensitive drum.

[0012] The above-mentioned conventional technique is further developed.

[0171] Hereinafter, the image forming apparatus and the process cartridge of the present embodiment will be described in conjunction with the accompanying drawings. The image forming apparatus forms an image on a recording material using an electrophotographic image forming process, for example. For example, it includes an electrophotographic copying apparatus, an electrophotographic printer (for example, a LED printer, a laser beam printer, etc.), an electrophotographic facsimile machine, and the like. In addition, the cartridge is mountable to and dismountable from the main assembly of the image forming apparatus. Among the cartridges, the one unitized with process means acting on the photoreceptor and the photoreceptor is particularly called process cartridge.

[0172] Also, a unit including a photosensitive drum and a coupling member as a unit is called a drum unit.

[0173] In the following embodiments, a full-color image forming apparatus relative to which four process cartridges can be mounted and dismounted is taken as a example, in Embodiment 4. However, the number of process cartridges mountable to the image forming apparatus is not limited to this. Likewise, the constituent elements disclosed in the embodiments are not intended to limit the material, arrangement, dimensions, other numerical values, etc. Unless otherwise specified. Unless otherwise specified, “above” means upward in the direction of gravity when the image forming apparatus is installed.

[General Description of Electrophotographic Image Forming Apparatus]

[0174] First, the overall structure of an embodiment of an electrophotographic image forming apparatus (image forming apparatus) according to this embodiment will be described in conjunction with FIG. 1.

[0175] FIG. 1 is a schematic sectional view of an image forming apparatus 100 according to this embodiment.

[0176] As shown in FIG. 1, the image forming apparatus 100 includes, as a plurality of image forming sections, first, second, third fourth image forming unit SY, SM, SC, and SK for forming images of respective colors, namely yellow (Y), magenta (M), cyan (C) and black (K). In this embodiment, the first to fourth image forming portions SY, SM, SC, and SK are arranged in a line in a substantially horizontal direction.

[0177] In this embodiment, the structures and operations of the process cartridges 7 (7Y, 7M, 7C, 7K) are substantially the same except that the colors of the images to be formed are different. Therefore, hereinafter, Y, M, C, and K will be omitted and explanation will be commonly applied unless otherwise stated.

[0178] In this embodiment, the image forming apparatus 100 has cylinders (hereinafter referred to as photosensitive drums) 1 each having a photosensitive layer, the cylinders being arranged side by side along a direction inclined slightly with respect to a vertical direction as a plurality of image bearing members. A scanner unit (exposure device) 3 is disposed below the process cartridge 7. In addition, around the photoconductive drum 1, a charging roller 2 or the like functioning as process means (process device, process member) acting on the photosensitive layer are arranged.

[0179] The charging roller 2 is charging means (charging device, charging member) for uniformly charging the surface of the photosensitive drum 1. The scanner unit (exposure device) 3 is exposure means (exposure device, exposure member) for forming an electrostatic image (electrostatic latent image) on the photosensitive drum 1 by exposing to a laser on the basis of image information. Around the photosensitive drum 1, there are provided a cleaning blade 6 as a developing device (hereinafter referred to as developing unit) 4 and cleaning means (cleaning device, cleaning member).

[0180] Further, an intermediary transfer belt 5 as an intermediary transfer member for transferring the toner image from the photosensitive drum 1 onto the recording material (sheet, recording medium) 12 is provided so as to face the four photosensitive drums 1.

[0181] The developing unit 4 of this embodiment uses a non-magnetic one-component developer (hereinafter referred to as toner) as a developer and employs a contact developing system in which a developing roller 17 as a developer carrying member contacts with the photosensitive drum 1.

[0182] With the above-described structure, the toner image formed on the photosensitive drum 1 is transferred onto the sheet (paper) 12, and the toner image transferred onto the sheet is fixed. As a process means acting on the photosensitive drum 1, the process cartridge includes a charging roller 2 for charging the photosensitive drum 1 and a cleaning blade 6 for cleaning toner remaining without being transferred onto the photosensitive drum 1. The untransferred residual toner remaining on the photosensitive drum 1 not having been transferred onto the sheet 12 is collected by the cleaning blade 6. Further, the residual toner collected by the cleaning blade 6 is accommodated in a removed developer accommodating portion (hereinafter referred to as a waste toner accommodating portion) 14a from the opening 14b. The waste toner accommodating portion 14a and the cleaning blade 6 are unitized to form a cleaning unit (photosensitive body unit, image bearing member unit) 13.

[0183] Further, the developing unit 4 and the cleaning unit 13 are unitized (made into a cartridge) to form a process cartridge 7. The image forming apparatus 100 is provided on the main assembly frame with guides (positioning means) such as a mounting guide and a positioning member (not shown). The process cartridge 7 is guided by the above-mentioned guide, and is configured to be mountable to and dismountable from the image forming apparatus main assembly (main assembly of the electrophotographic image forming apparatus) 100A.

[0184] Toners of respective colors of yellow (Y), magenta (M), cyan (C) and black (K) are accommodated in the process cartridges 7 for the respective colors.

[0185] The intermediary transfer belt 5 contacts the photosensitive drum 1 of each process cartridge and rotates (moves) in the direction indicated by an arrow B in FIG. 1. The intermediary transfer belt 5 is wound around a plurality of support members (a drive roller 51, a secondary transfer opposed roller 52, a driven roller 53). On the inner peripheral surface side of the intermediary transfer belt 5, four primary transfer rollers 8 as primary transfer means are juxtaposed so as to face each photosensitive drum 1. A secondary transfer roller 9 as a secondary transfer means is disposed at a position facing the secondary transfer opposing roller 52 on the outer peripheral surface side of the intermediary transfer belt 5.

[0186] At the time of image formation, the surface of the photosensitive drum 1 is first uniformly charged by the charging roller 2. Then, the surface of the thus charged photosensitive drum 1 is scanned by and exposed to laser beam corresponding to image information emitted from the scanner unit 3. By this, an electrostatic latent image corresponding to image information is formed on the photosensitive drum 1. The electrostatic latent image formed on the photosensitive drum 1 is developed into a toner image by the developing unit 4.

[0187] The photosensitive drum is a rotatable member (image bearing member) that rotates in a state of carrying an image (developer image, toner image) formed with a developer (toner) on the surface thereof.

[0188] The toner image formed on the photosensitive drum 1 is transferred (primary transfer) onto the intermediary transfer belt 5 by the operation of the primary transfer roller 8.

[0189] For example, at the time of forming a full-color image, the above-described process is sequentially performed in the four process cartridges 7 (7Y, 7M, 7C, 7K). The toner images of the respective colors formed on the photosensitive drums 1 of the respective process cartridges 7 are sequentially primary-transferred so as to be superimposed on the intermediary transfer belt 5. Thereafter, in synchronism with the movement of the intermediary transfer belt 5, the recording material 12 is fed to the secondary transfer portion. The four color toner images on the intermediary transfer belt 5 are altogether transferred onto the recording material 12 conveyed to the secondary transfer portion constituted by the intermediary transfer belt 5 and the secondary transfer roller 9.

[0190] The recording material 12 to which the toner image has been transferred is conveyed to a fixing device 10 as fixing means. By applying heat and pressure to the recording material 12 in the fixing device 10, the toner image is fixed on the recording material 12. Further, the primary transfer residual toner remaining on the photosensitive drum 1 after the primary transferring process is removed by the cleaning blade 6 and collected as waste toner. Further, the secondary transfer residual toner remaining on the intermediary transfer belt 5 after the secondary transfer step is removed by the intermediary transfer belt cleaning device 11.

[0191] The image forming apparatus 100 is also capable of forming monochrome or multicolor images using desired single or some (not all) image forming units.

[General Description of Process Cartridge]

[0192] Referring to FIGS. 2, 3, and 4 the process cartridge 7 (cartridge 7) mounted in the image forming apparatus main assembly 100A of this embodiment will be described.

[0193] The cartridge 7a containing the yellow toner, the cartridge 7b containing the magenta toner, the cartridge 7c containing the cyan toner and the cartridge 7d containing the black toner have the same structure. Therefore, in the following description, each of the cartridges 7a, 7b, 7c, 7d will be referred to simply as a cartridge 7. The respective cartridge components will also be described in the same manner.

[0194] FIG. 2 is an external perspective view of the process cartridge 7. Here, as shown in FIG. 2, the direction of the rotation axis of the photosensitive drum 1 is defined as a Z direction (arrow Z1, arrow Z2), the horizontal direction in FIG. 1 as X direction (arrow X1, arrow X2), the vertical direction is a Y direction (arrow Y1, arrow Y2).

[0195] FIG. 3 is a schematic cross-sectional view of the process cartridge 7 viewed in the Z direction in a state (attitude) in which the photosensitive drum 1 and the developing roller 17 are in contact with each other, which is mounted to the image forming apparatus 100.

[0196] The process cartridge 7 comprises two units, namely a cleaning unit 13 including the photosensitive drum 1, the charging roller 2 and the cleaning blade 6 as a unit, and a developing unit 4 including a developing member such as the developing roller 17.

[0197] The developing unit 4 has a developing frame 18 for supporting various elements in the developing unit 4. The developing unit 4 includes the developing roller 17 as a developer carrying member which is rotatable in the direction of the arrow D (counterclockwise direction) in contact with the photosensitive drum 1. The developing roller 17 is rotatably supported by the developing frame 18 through development bearings 19 (19R, 19L) at both end portions with respect to the longitudinal direction (rotational axis direction) thereof. Here, the developing bearings 19 (19R, 19L) are mounted to respective side portions of the developing frame 18, respectively.

[0198] In addition, the developing unit 4 is provided with a developer accommodating chamber (hereinafter, toner accommodating chamber) 18a and a developing chamber 18b in which the developing roller 17 is provided.

[0199] In the developing chamber 18b, there are provided a toner supply roller 20 as a developer supply member which contacts the developing roller 17 and rotates in the direction of arrow E, and a developing blade 21 as a developer regulating member for regulating the toner layer of the developing roller 17. The developing blade 21 is fixed and integrated to the fixing member 22 by welding or the like.

[0200] A stirring member 23 for stirring the contained toner and for conveying the toner to the toner supplying roller 20 is provided in the toner accommodating chamber 18a of the developing frame 18.

[0201] The developing unit 4 is rotatably coupled to the cleaning unit 13 around the fitting shafts 24 (24R, 24L) fitted in the holes 19Ra, 19La provided in the bearing members 19R, 19L. Further, in the developing unit 4, the developing roller 17 is urged by the pressure spring 25 (25R, 25L) in a direction of contacting to the photosensitive drum 1. Therefore, at the time of image formation using the process cartridge 7, the developing unit 4 turns (rotates) in the direction of an arrow F about the fitting shaft 24, so that the photosensitive drum 1 and the developing roller 17 are in contact with each other.

[0202] The cleaning unit 13 has a cleaning frame 14 as a frame for supporting various elements in the cleaning unit 13.

[0203] FIG. 4 is a cross-sectional view taken along an imaginary plane including a rotation center of the photosensitive drum 1 of the process cartridge 7. The side (with respect to the Z1 direction) where the coupling member 28 receives the driving force from the image forming apparatus main assembly is referred to as the driving side (back side) of the process cartridge 7. The side opposite to the driving side (with respect to the Z2 direction) is referred to as the non-driving side (front side) of the process cartridge 7.

[0204] On the end opposite from the coupling member 28 (the end portion on the non-driving side of the process cartridge), there is provided a electrode (electrode portion) in contact with the inner surface of the photosensitive drum 1, and this electrode functions as the electrical ground by contacting the main assembly.

[0205] The coupling member 28 is mounted to one end of the photosensitive drum 1, and a non-driving side flange member 29 is mounted to the other end of the photosensitive drum 1 to constitute a photosensitive drum unit 30. The photosensitive drum unit 30 receives a driving force from a main assembly driving shaft 101 provided in the image forming apparatus main assembly 100A via the coupling member 28 (driving force is transmitted from the main assembly driving shaft 101).

[0206] The coupling member 28 is configured to be coupled to and detached from the main assembly driving shaft 101.

[0207] The coupling member 28 is also a flange member (driving side flange member) mounted to the driving side end portion of the photosensitive drum 1.

[0208] As shown in FIG. 4, the Z1 side of the coupling member 28 has a cylindrical shape (cylindrical portion 71). The cylindrical portion 71 protrudes toward the Z1 side (outside in the axial direction) beyond the end portion of the photosensitive drum 1. The outer peripheral portion of the cylindrical portion 71 is the outer peripheral surface 71a. On the outer circumferential surface 71a, a cut-away portion 71d is provided for forming a base portion 74 which will be described hereinafter. In the cylindrical portion 71, a portion on the Z1 side of the cut-away portion 71d is a borne portion 71c. The borne portion 71c is rotatably supported by the bearing portion provided in a drum unit bearing member 39R. In other words, the borne portion 71c is supported by the bearing portion of the drum unit bearing member 39R, so that the photosensitive drum unit 30 can rotate.

[0209] Similarly, the non-driving side flange member 29 provided on the non-driving side of the photosensitive drum unit 30 is rotatably supported by a drum unit bearing member 39L. The non-driving side flange member 29 has a cylindrical portion (cylindrical portion) projecting from the end portion of the photosensitive drum 1, and the outer peripheral surface 29a of this cylindrical portion is rotatably supported by the drum unit bearing member 39L.

[0210] The drum unit bearing member 39R is disposed on the driving side of the process cartridge 7, and the drum unit bearing member 39L is disposed on the non-driving side of the process cartridge 7.

[0211] As shown in FIG. 4, when the process cartridge 7 is mounted in the apparatus main assembly 100A, the drum unit bearing member 39R abuts to the rear cartridge positioning section 108 provided in the image forming apparatus main assembly 100A. Further, the drum unit bearing member 39L abuts to the front side cartridge positioning portion 110 of the image forming apparatus main assembly 100A. Thereby, the cartridge 7 is positioned in the image forming apparatus 100A.

[0212] In the Z direction of this embodiment, the position where the drum unit bearing member 39R supports the borne portion 71c is made close to the position where the drum unit bearing member 39R is positioned at the rear side cartridge positioning portion 108. By doing so, it is possible to suppress inclination of the coupling member 28 when the process cartridge 7 is mounted in the apparatus main assembly 100A.

[0213] The borne portion 71c is disposed so that the position where the bearing member 39R supports the supported portion 71c and the position where the bearing member 39R is positioned at the rear side cartridge positioning portion 108 can be close to each other. That is, the borne portion 71c is disposed on the free end side (the Z1 direction side) of the outer peripheral surface 71a of the cylindrical portion 71 provided in the coupling member 28.

[0214] Similarly, in the Z direction, the position where the drum unit bearing member 39L rotatably supports the non-driving side flange member 29 is arranged at a position close to the position where the drum unit bearing member 39L is positioned on the near side cartridge positioning portion 110. By this, the inclination of the non-driving side flange member 29 is suppressed.

[0215] The drum unit bearing members 39R and 39L are mounted to the sides of the cleaning frame 14, respectively, and support the photosensitive drum unit 30. By this, the photosensitive drum unit 30 is supported so as to be rotatable relative to the cleaning frame 14.

[0216] In addition, a charging roller 2 and a cleaning blade 6 are mounted to the cleaning frame 14, and they are arranged so as to be in contact with the surface of the photosensitive drum 1. In addition, charging roller bearings 15 (15R, 15L) are mounted to the cleaning frame 14. The charging roller bearing 15 is a bearing for supporting the shaft of the charging roller 2.

[0217] Here, the charging roller bearings 15 (15R, 15L) are mounted so as to be movable in the direction of the arrow C shown in FIG. 3. A rotating shaft 2a of the charging roller 2 is rotatably mounted to the charging roller bearing 15 (15R, 15L). The charging roller bearing 15 is urged toward the photosensitive drum 1 by a pressing spring 16 as an urging means. As a result, the charging roller 2 abuts against the photosensitive drum 1 and is rotated by the photosensitive drum 1.

[0218] The cleaning frame 14 is provided with a cleaning blade 6 as a cleaning means for removing the toner remaining on the surface of the photosensitive drum 1. The cleaning blade 6 is formed by unitizing a blade-shaped rubber (elastic member) 6a that abuts against the photosensitive drum 1 to remove toner on the photosensitive drum 1 and a supporting metal plate 6b that supports the blade-like rubber (elastic member) 6a. In this embodiment, the support metal plate 6b is fixed to the cleaning frame 14 with screws.

[0219] As described in the foregoing, the cleaning frame 14 has an opening 14b for collecting the transfer residual toner collected by the cleaning blade 6. The opening 14b is provided with a blowing prevention sheet 26 which is in contact with the photosensitive drum 1 and seals between the photosensitive drum 1 and the opening 14b so as to suppress toner leakage in the upward direction of the opening 14b.

[0220] In this manner, by employing the structure in which the components related to the image formation are unitized in a cartridge detachably mountable to the apparatus main assembly, the maintenance easiness is improved. In other words, the user can easily perform maintenance of the apparatus by exchanging the process cartridge. Therefore, it is possible to provide an apparatus for which the maintenance operation can be performed not only by a serviceman but also by a user.

[Structure of Main Assembly Driving Shaft]

[0221] Referring to FIGS. 5, 6, 7, 8, and 9, structures of the main assembly driving shaft 101 will be described.

[0222] FIG. 5 is an external view of the main assembly driving shaft.

[0223] FIG. 6 is a cross-sectional view taken along the rotation axis (rotation axis) of the main assembly driving shaft 101 mounted to the image forming apparatus main assembly.

[0224] FIG. 7 is a cross-sectional view of the coupling 28 and the main assembly driving shaft 101 taken along the rotation axis (rotation axis).

[0225] FIG. 8 is a cross-sectional view of the coupling member 28 and the main assembly driving shaft 101 taken along a plane perpendicular to the rotation axis.

[0226] FIG. 9 is a cross-sectional view of the coupling 28 and the main assembly driving shaft 101 taken along the rotation axis.

[0227] As shown in FIG. 5, the main assembly driving shaft 101 is provided with a gear portion 101e, a shaft portion 101f, a rough guide portion 101g and a borne portion 101d.

[0228] A motor (not shown) as a drive source is provided in the image forming apparatus main assembly 100A. From the motor, the gear portion 101e receives the rotational driving force so that the main assembly driving shaft 101 rotates. Further, the main assembly driving shaft 101 includes a rotatable projecting shaft portion 101f protruding toward the cartridge side from the gear portion 101e along the rotation axis thereof. The rotational driving force received from the motor is transmitted to the cartridge 7 side by way of the groove-shaped drive transmission groove 101a (recessed portion, drive passing portion) provided in the shaft portion 101f. In addition, the shaft portion 101f has a semispherical shape 101c at its free end portion.

[0229] The main assembly drive transmission groove 101a is shaped so that a part of an engagement portion 73 which will be described hearing after can enter. Specifically, it is provided with a main assembly drive transmission surface 101b as a surface that contacts the driving force receiving surface (driving force receiving portion) 73a of the coupling member 28 to transmit the driving force.

[0230] Further, as shown in FIG. 5, the main assembly drive transmission surface 101b is not a flat surface but a shape twisted about the rotational axis of the main assembly driving shaft 101. The twisting direction is such that the downstream side in the Z1 direction of the main assembly driving shaft 101 is upstream of the downstream side in the Z2 direction thereof, with respect to the rotational direction of the main assembly driving shaft 101. In this embodiment, the amount of twisting along the rotational axis direction of the cylinder of the engaging portion 73 is set to about 1 degree per 1 mm. The reason why the main assembly drive transmission surface 101b is twisted will be described hereinafter.

[0231] Also, the main assembly drive transmission groove 101a provided on the Z2 direction side surface with a main assembly side removing taper 101i. The main assembly side extraction taper 101i is a taper (inclined surface, inclined portion) for assisting the engagement portion 73 to disengage from the drive transmission groove 101a when dismounting the process cartridge 7 from the apparatus main assembly 100A. The details thereof will be described hereinafter.

[0232] Here, when the driving force is transmitted from the drive transmission groove 101a to the engagement portion 73, it is desirable that the main assembly drive transmission surface 101b and the driving force receiving surface (driving force receiving portion) 73a are assuredly in contact with each other. Therefore, in order to prevent the surface other than the main assembly drive transmission surface 101b from coming into contact with the engagement portion 73, the main assembly drive transmission groove 101a has a clearance (G) relative to the engagement portion 73 in the rotational axis direction, the circumferential direction and in the radial direction (FIGS. 8 and 9).

[0233] Further, on the free end side in the axial direction of the main assembly drive transmission groove 101a, there is provided a main assembly side removing taper 101i as an inclined surface (inclined portion). Further, in the axial direction of the main assembly driving shaft 101, the center 101h of the semispherical shape 101c is disposed within the range of the main assembly drive transmission groove 101a (FIG. 7). In other words, when the center 101h and the main assembly drive transmission groove 101a are projected on the axis of the main assembly driving shaft 101 on the axis of the main assembly driving shaft 101, the projection area of the center 101h on the axis is within the projection area of the main assembly drive transmission groove 101a. The rough guide portion 101g is provided between the shaft portion 101f and the gear portion 101e in the axial direction (FIG. 6). As shown in FIG. 7, the rough guide portion 101g has a tapered shape at the free end portion on the shaft portion 101f side, and the outer diameter D6 of the rough guide portion 101g is, as shown in FIG. 7, is smaller than the inner diameter D2 of inner surface 71b of the cylindrical portion 71 of the coupling member 28. The outer diameter D6 of the rough guide portion 101g is larger than the outer diameter D5 of the shaft portion 101f as shown in FIG. 5. Thus, when the cartridge 7 is inserted into the image forming apparatus main assembly 100A, the main assembly driving shaft 101 is guided to be along the coupling member 28 so as to reduce the axial misalignment between the rotation center of the cylindrical portion 71 and the rotation center of the shaft portion 101f. Therefore, the rough guide portion 101g can be said to be an insertion guide.

[0234] The rough guide portion 101g is set to have such a dimensional relationship that it does not abut on the inner peripheral surface 71b, after the mounting of the cartridge 7 to the image forming apparatus main assembly 100A is completed.

[0235] As shown in FIG. 6, the borne portion 101d is disposed on the opposite side of the rough guide portion 101g across the gear portion 101e. The borne portion 101d is rotatably supported by a bearing member 102 provided in the image forming apparatus main assembly 100A.

[0236] Further, as shown in FIG. 6, the main assembly driving shaft 101 is urged toward the cartridge 7 side by a spring member 103 of the image forming apparatus main assembly 100A. However, the movable amount (play) of the main assembly driving shaft 101 in the Z direction is about 1 mm which is sufficiently smaller than the width, measured in the Z direction, of the driving force receiving surface 73a which will be described hereinafter.

[0237] As described above, the main assembly driving shaft 101 is provided with the main assembly drive transmission groove 101a, and the coupling member 28 is provided with the engagement portion 73, to transmit the drive from the main assembly 100A to the cartridge 7 (drum unit 30).

[0238] As will be described in detail hereinafter, the engaging portion 73 is provided at the free end of the elastically deformable base portion 74. Therefore, the engaging portion 73 is configured to be movable at least outwardly in the radial direction when the cartridge 7 is mounted to the apparatus main assembly 100A. Therefore, as the cartridge 7 is inserted into the apparatus main assembly 100A, the engagement portion 73 enters the drive transmission groove 101a, and the engagement portion 73 and the main assembly drive transmission groove 101a can engage with each other.

[Structure of Coupling Member]

[0239] Referring to FIGS. 4, 10, 11, 12, 13, 14, and 15, the coupling member 28 of this embodiment will be described in detail.

[0240] FIG. 10 is a perspective view of the coupling member 28.

[0241] FIG. 11 is a cross-sectional view of the coupling member 28 taken along a plane perpendicular to the axis of rotation of the coupling member 28 and including the base portion 74.

[0242] FIG. 12 is a cross-sectional perspective view of the coupling member 28.

[0243] FIG. 13 is a longitudinal sectional view of the coupling member 28 taken along the rotation axis.

[0244] FIG. 14 is a cross-sectional view of the coupling member 28 and the main assembly driving shaft 101 taken along a plane perpendicular to the rotation axis and include in the base portion 74.

[0245] FIG. 15 is a longitudinal sectional view of the coupling member 28 and the main assembly driving shaft 101 taken along the rotation axis.

[0246] As shown in FIGS. 10 and 12, the coupling member 28 includes a mounting portion 72, a cylindrical portion 71, a flange portion 75, an engaging portion 73, a base portion 74, and an aligning portion 76. The mounting portion 72 is a portion to be mounted to the photosensitive drum 1. The cylindrical portion 71 has a substantially cylindrical configuration. The cylindrical portion 71 has a borne portion 71c as described hereinbefore, and the borne portion 71c is rotatably supported by a bearing portion provided in the drum unit bearing member 39R.

[0247] The engaging portion 73 projects at least radially inwardly of the coupling member 28 in order to engage with the main assembly driving shaft 101. The engaging portion 73 has a driving force receiving surface 73a. The driving force receiving surface 73a is a driving force receiving portion for receiving the driving force from the main assembly driving shaft 101 by contacting with the driving groove.

[0248] The base portion (deforming portion, extending portion) 74 is formed by cut-away portions 71d provided in the cylindrical portion 71 of the coupling member 28. The cut-away portion 71d is angular U-shaped. The base portion 74 is deformable with the root portion 74a of the base portion 74 as a fulcrum point, and movably supports the engaging portion 73. The engaging portion 73 is movable at least in the radial direction of the coupling member.

[0249] That is, the driving force receiving surface (driving force receiving portion) 73a is supported by the base portion (supporting portion base portion) 74 and the engaging portion (projecting portion) 73. The base portion 74 and the engaging portion 73 are support portions for supporting the driving force receiving surface 73a. In this embodiment, the support portion extends substantially parallel with the axial direction of the coupling member 28.

[0250] As shown in FIG. 10, the mounting portion 72 includes a press-fit portion 72d press-fitted to the inner diameter of the cylinder of the photosensitive drum 1, a clamp groove 72e, a press-fit guide portion 72f provided in the rear side (with respect to Z2 direction side) of the press-fit portion 72d.

[0251] The press-fitting portion 72d as a joining portion is a portion for fixing the coupling member 28 to the photosensitive drum 1 by being pressed into the photosensitive drum 1. Specifically, the inner diameter of the cylinder of the photosensitive drum 1 and the outer diameter of the press-fit portion 72d are dimensioned so as to establish a press-fitting relation. The structure is not limited to the above-described structure in which the fastening force by clamping is enhanced or when the cylinder inner diameter and the press-fitting portion 72d are fixed by adhesion.

[0252] As shown in FIG. 10, the clamp groove 72e has a groove shape (a recessed portion) provided on the photosensitive drum 1 side of the press-fit portion 72d with respect to the Z axis direction. The clamp grooves 72e are provided at equally distant two positions around the rotation axis of the coupling member 28. In the rotation axis direction of the drum unit 30 (the rotation axis direction of the coupling member 28), the clamp groove 72e and the flange portion 75 are disposed so as to overlap with each other.

[0253] The axial line (rotation axis, rotation center line) Ax of the drum unit 30 is an imaginary straight line extending passing through the rotation center of the drum unit 30. The axis of the photosensitive drum 1 and the axis of the coupling member 28 are disposed so as to substantially overlap with each other, and these axes are substantially aligned with the axis Ax of the drum unit 30. Therefore, unless otherwise noted, each axis is used interchangeably in the following description.

[0254] Also, the axial direction (rotation axis direction) is the direction in which the axis extends. The axial direction of the drum unit 30 and the axial direction of the coupling member 28 have the same meaning as the longitudinal direction (Z direction) of the drum unit 30.

[0255] Further, “X and Y overlap in the direction A” means that when X and Y are projected on a straight line extending in parallel to the direction A, at least a part of the projection area of X overlaps with at least a part of the projection area of Y.

[0256] That is, when the clamp groove 72e and the flange portion 75 are projected onto the rotation axis Ax of the drum unit 30 (coupling member 28), the projection area of the clamp groove 72e and the projection area of the flange portion 75 are at least partly overlap with each other.

[0257] In the case of projecting something on a line, the projecting direction is perpendicular to the line unless otherwise stated. For example, “projecting A on the axis” means “projecting A in a direction perpendicular to the axis with respect to the axis”. By clamping a part of the end of the photosensitive member 1 at the side of the coupling member 28, the photosensitive drum 1 is plastically deformed. As a result, a part of the photosensitive member enters the inside of the clamp groove 72e to firmly fixe the photosensitive drum 1 and the coupling member 28 with each other. Clamping refers to an operation of joining parts by plastic deformation.

[0258] In this embodiment, it is connecting to the coupling member 28 by plastically deforming a part of the cylinder (aluminum) of the photosensitive drum 1. In this embodiment, the clamp groove 72e is used as a example of means for securedly fixing the coupling member 28 to the photosensitive drum 1, but it is also possible to fix the coupling member 28 by adhesion between the cylinder inner diameter portion and the press-fit portion 72d or another fixing means can be used. Therefore, the clamp groove 72e is not an inevitable structure.

[0259] The press-fit guide portion 72f has such a shape as to make it easier to mount the coupling member 28 to the photosensitive drum 1 and to stably press-fit the press-fit portion 72d into the photosensitive drum 1 at the time when the coupling member 28 is assembled to the photosensitive drum 1. Specifically, the outer diameter of the press-fit guide portion 72f is smaller than the outer diameter of the press-fit portion 72d and the cylinder inner diameter of the photosensitive drum 1, and has a guide taper 72g on the free end side in the mounting direction to the photosensitive drum 1. The guide taper 72g is an inclined portion provided on the coupling member 28 in order to facilitate the insertion of the coupling member 28 into the inside of the photosensitive drum 1.

[0260] As described above, the cylindrical portion 71 has a borne portion 71c on the free end side (the Z1 direction side) of the outer peripheral surface 71a (as shown in FIG. 4, 10). In addition, a cut-away portion 71d is provided on the press-fitting portion 72e side of the borne portion 71c of the cylindrical portion 71. The cut-away portion 71d forms a base portion 74 that elastically deformably supports the engagement portion 73 (the details of the engagement portion 73 will be described hereinafter). That is, in the Z direction, the cut-away portion 71d, the engaging portion 73 and the base portion 74 are provided between the borne portion 71c and the press-fitting portion 72e.

[0261] In other words, the coupling member 28 has the cut-away portion 71d, the engaging portion 73, and the borne portion 71c having a outer shape of the cylinder on the Z1 direction side (outside in the axial direction) from the base portion 74. By using such a shape, the engaging portion 73 and the base portion 74 are not exposed at the outer surface of the cartridge 7. Therefore, the engaging portion 73 and the base portion 74 can be protected by the drum unit bearing member 39R and the borne portion 71c.

[0262] This can prevent the user from unintentionally touching the engaging portion 73 and the base portion 74, and suppress something directly touching the engaging portion 73 and the base portion 74 when the cartridge 7 falls down.

[0263] Further, as shown in FIG. 12, the inner peripheral surface 71b of the cylindrical portion 71 has a tapered shape at the front free end (Z1 direction). The tapered shape is an inclined portion (inclined surface) for guiding the main assembly driving shaft 101 being inserted into the cylindrical portion 71.

[0264] When the main assembly driving shaft 101 is inserted into the cylindrical portion 71, the inner peripheral surface 71b of the cylindrical portion 71 guides the main assembly driving shaft 101. The inner peripheral surface 71b of the cylindrical portion 71 is a cartridge side guide portion for guiding the main assembly driving shaft 101 and has a circumferential shape.

[0265] When the cartridge 7 is inserted into the image forming apparatus main assembly 100A, the main assembly driving shaft 101 is guided so as to follow the coupling member 28 to reduce the axial deviation between the rotation center of the cylindrical portion 71 and the rotation center of the shaft portion 101f. Further, as shown in FIG. 7, the inner diameter D2 of the inner peripheral surface 71b is larger than the outer diameter D6 of the shaft portion 101f of the main assembly driving shaft 101. Therefore, after the mounting of the cartridge 7 to the image forming apparatus main assembly 100A is completed, the inner peripheral surface 71b does not contact with the rough guide portion 101g.

[0266] As shown in FIG. 13, the flange portion 75 has a shape protruding outward from the press-fit portion 72d in the radial direction. When the coupling member 28 is assembled to the photosensitive drum 1, the end surface of the photosensitive drum 1 abuts to the end surface 75b of the flange portion 75, thereby determining the positions of the photosensitive drum 1 and the coupling member 28 in the Z direction.

[0267] As shown in FIG. 11, the engaging portions 73 are arranged at three positions at regular intervals in the circumferential direction of the coupling member 28 (120 degrees interval, substantially equally spaced). Similarly, the base portion 74 and the cut-away portion 71d are also arranged at three positions at regular intervals in the circumferential direction of the cylindrical portion 71. The base portion 74 is provided by cut-away portions 71d. The base portion 74 has a fixed end in the cylindrical portion 71 and is elastically deformable with the fixed end as a fulcrum.

[0268] The base portion 74 is a portion (extending portion, extending portion) extending along the axial direction of the coupling member 28 (the axial direction of the photosensitive drum unit 30). That is, the base portion 74 extends at least outwardly in the axial direction.

[0269] An engaging portion 73 is provided at the tip (free end) of the base portion 74. The engaging portion 73 is a projecting portion (protruding portion, protrusion) projected toward the inner side in the radial direction of the coupling member 28 (the inner side in the radial direction of the photosensitive drum unit 30). That is, the engaging portion 73 is a projecting portion (protrusion, protrusion) projecting in a direction crossing with the direction in which the base portion 74 extends.

[0270] The shape of the cross section of the engaging portion 73 is not circular (non-circular shape), more preferably it has a corner. This is because then the engaging portion 73 reliably engages with the driving transmission groove 101a formed in the main assembly driving shaft 101.

[0271] That is, when the supporting portion (the engaging portion 73) is cut perpendicularly to the axis Ax of the coupling member at the position where the drive receiving portion 73a is provided, the shape of the cross-section is non-circular.

[0272] The engaging portion 73 is supported by an elastically deformable base portion 74 and can move in the radial direction of the coupling member 28 by deformation of the base portion 74. In other words, the base portion 74 is also a deforming portion (elastic deforming portion, flexible portion) which is deformed when it is subjected to a external force and provides a restoring force in a direction returning to a position in the free state.

[0273] Specifically, when the engaging portion 73 contacts the outer peripheral surface of the main assembly driving shaft 101, the engaging portion 73 is elastically deformed so that the engaging portion 73 moves outwardly in the radial direction along the outer peripheral surface of the main assembly driving shaft 101. Thereafter, when the engagement portion 73 is at the same position (same phase) as the main assembly side drive transmission groove 101a provided on the outer peripheral surface of the main assembly driving shaft 101, the elastic deformation of the engagement portion 73 is eliminated. Then, the engaging portion 73 moves inwardly in the radial direction, so that a part of the engaging portion 73 can enter the main assembly drive transmission groove 101a.

[0274] from the stand point of the driving stability, it is preferable to dispose a plurality of the engaging portions 73 in the circumferential direction of the cylinder.

[0275] The driving force receiving surface 73a of the coupling member 28 has a shape twisted about the axis of the coupling member 28, and in this embodiment, the amount of twisting is set to be the same as that of the main assembly drive transmission surface 101b.

[0276] it will suffice if the driving force receiving surface 73a has a different phase, in the rotational direction, of two points in contact with the driving shaft 101. That is, the driving force receiving surface 73a may not necessarily have a twisted shape if it has the same function as the twisted surface.

[0277] For example, it will suffice if the shape is such that outer side (downstream side in Z1 direction) of the driving force receiving surface 73a is in the upstream side of the inner side (downstream side in Z2 direction) with respect to the peripheral moving direction of the rotation of the photosensitive drum 1. In other words, a straight line connecting the cylinder inner end portion and the cylinder outer end portion along the cylinder axis direction of the engagement portion 73 crosses with the rotation axis of the cylinder. The driving force receiving surface 73a is an inclined portion inclined with respect to the axis of the coupling member 28.

[0278] By employing the twisted one in claim shape of the driving force receiving surface 73a in this manner, the photosensitive drum unit 30 receives the force in the direction of attracting toward the borne portion 101d of the main assembly driving shaft 101 when the driving force receiving surface 73a receives the driving force.

[0279] Here, in FIG. 8, the engaging portion 73 can retract and move outwardly in the radial direction of the coupling member 28 (radial direction of the photosensitive drum unit 30). The driving force receiving surface 73a provided in the engaging portion 73 is inclined with respect to the moving direction of the engaging portion 73. In the cross-sectional view shown in FIG. 8, a straight line B1 is a straight line along the direction in which the engaging portion 73 moves in the retraction (the direction in which it moves in the radial direction). The straight line B2 is a straight line along the driving force receiving surface 73a. It is understood that the straight line B1 and the straight line B2 crosses with each other. By this, the driving force receiving surface 73a bites into the driving transmission groove 101a in a state that the driving force receiving surface 73a is in contact with the driving transmission groove 101a, so that the engaging portion 73 does not easily retreat from the driving transmission groove 101a. That is, the engagement state between the engagement portion 73 and the drive transmission groove 101a is stabilized.

[0280] Particularly, the driving force receiving surface 73a is inclined relative to the moving direction of the engaging portion 73 (line B1) such that the inner diameter side (free end side) is upstream of the outer diameter side (root side) with respect to the rotational direction of the coupling member 28. Therefore, when the coupling member 28 (photosensitive drum unit 30) rotates, the force received from the driving force receiving surface 73 is in a direction to engage the engaging portion 73 with the main assembly driving transmission groove 101a. The state of engagement between the engaging portion 73 and the main assembly drive transmission groove 101a is stabilized and the disengagement between the engagement portion 73 and the main assembly drive transmission groove 101a is suppressed.

[0281] As shown in FIG. 13, the engaging portion 73 has a insertion tapered surface 73d on the outer side (the Z1 direction side) of the photosensitive drum unit 30 in the Z direction. The insertion tapered surface 73d is an inclined portion facing outwardly in the axial direction. When the coupling member 28 is coupled with the main driving shaft 101, the insertion tapered surface 73d rides on the main driving shaft 101, so that the engagement portion 73 retracts to the outside in the radial direction. The insertion tapered surface 73d is an at-mounting force receiving portion for receiving a force for retracting in the radial direction 73 when the cartridge is mounted.

[0282] Further, the engaging portion 73 has a dismounting tapered surface 73e as an at-dismounting force receiving portion on the inner side (the Z2 direction side) of the photosensitive drum unit 30 in the Z direction. The dismounting tapered surface 73e is an inclined portion facing inwardly in the axial direction. The dismounting tapered surface 73e rides on the main assembly driving shaft 101 when the cartridge is dismounted, that is, when disconnecting the coupling member 28 from the main assembly driving shaft 101. When the dismounting tapered surface 73e receives a force from the main assembly driving shaft, the engagement portion 73 moves radially inwardly to disengage from the main assembly driving shaft.

[0283] With these structures, it is possible to improve the mounting and dismounting properties of the coupling member 28 to the main driving shaft 101. Both of the two tapered surfaces are inclined parts inclined with respect to the axial direction.

[0284] When the cartridges mounted, the inserted taper surface 73d and the semispherical 101c abuts to each other to move the engagement portion 73 outwardly in the radial direction of the driving shaft. In addition, at the time of dismounting of the cartridge, the dismounting tapered surface 73e and the main assembly side dismounting taper 101i are brought into contact to each other to move the engagement portion 73 (driving force receiving surface 73a) toward the outside in the radial direction of the main assembly driving shaft 101. When the driving force receiving portion 73a of the coupling member 28 is connected to or disconnected from the main assembly driving shaft 101, the driving force receiving portion 73a receives a force from the main assembly driving shaft 101, so that the driving force receiving portion 73a of the coupling member 28 is moved radially outwardly.

[0285] Further, the engaging portion 73 is placed so that the length L2 of the driving force receiving surface 73 with respect to the distance L1 from the front end surface of the cylindrical portion 71 to the front end surface of the engaging portion 73 in the Z direction satisfies L1>L2.

[0286] The aligning portion 76 has a radial direction positioning portion 76a. The radial direction positioning portion 76a is a portion for determining the position of the main assembly driving shaft 101 in the radial direction. In other words, the radial direction positioning portion 76a is a portion for determining the radial direction position of the coupling member 28 with respect to the main assembly driving shaft 101. That is, the radial direction positioning portion 76a is a positioning portion for determining the relative positional relationship between the main assembly driving shaft 101 and the coupling member.

[0287] The radial direction positioning portion 76a has a arcuate curved surface, and this curved surface contacts with the outer peripheral surface of the main assembly driving shaft 101, to limit the movement of the main assembly driving shaft 101 in the radial direction. That is, the radial direction positioning portion 76a has a curved surface which faces the axis line side of the coupling member 28 along the circumferential direction (rotational direction) of the coupling member 28. The radial direction positioning portion 76a is disposed axially inward of the inner circumferential surface 71b (FIG. 12), and the inner diameter of the radial direction positioning portion 76a is smaller than the inner circumferential surface 71b. The inner peripheral surface 71b is a first inner diameter portion having a relatively large diameter and the radial direction positioning portion 76a is a second inner diameter portion having a relatively small diameter.

[0288] As shown in FIG. 14, the radial direction positioning portion 76a is disposed at a position away from the engaging portion 73 as viewed along the axial direction of the coupling member 28. Further, the radial direction positioning portion 76a is disposed outside the free end of the engagement portion 73 (the free end of the driving force receiving surface 73a) in the radial direction of the coupling member 28, and is disposed inside of the fixed end (base portion) of the base portion 74.

[0289] On the other hand, in the Z direction, the radial direction positioning portion 76a is disposed at a position overlapping with the engaging portion 73 (FIG. 15). That is, when the radial direction positioning portion 76a and the engaging portion 73 are projected perpendicularly to the axis of the coupling member 28, at least parts of the projected areas of them overlaps with each other on the axis.

[0290] With such a arrangement relationship, even if the main assembly driving shaft 101 is inclined with the radial direction positioning portion 76a as a fulcrum, the relative position between the main assembly driving shaft 101 and the engagement portion 73 is unlikely to change, and therefore, the engagement between the main assembly driving shaft 101 and the engaging portion 73 are not influenced.

[0291] The inner diameter D7 of the radial direction positioning portion 76a is substantially the same as the outer diameter D5 of the shaft portion 101f of the main assembly driving shaft 101. As described above, the engaging portions 73 are arranged at three positions (120 degrees interval, substantially equally spaced) at regular intervals in the circumferential direction of the coupling member 28. Correspondingly, three radial positioning portions 76a are similarly arranged at regular intervals in the circumferential direction of the coupling member 28. As a result, the radial direction positioning portion 76a can position the coupling 28 in the radial direction relative to the shaft portion 101f at three positions.

[0292] In addition, the aligning portion 76 has an abutment portion 76b. As shown in FIG. 15, when the driving force is transmitted from the main assembly driving shaft 101 to the coupling member 28, the abutment portion 76b is brought into contact with the semispherical shape 101c. The semispherical shape 101c is a substantially semispherical portion provided at the tip of the main assembly driving shaft 101.

[0293] Further, in the Z direction, the abutment portion 76b is disposed in the coupling member 28 such that the center 101h of the semispherical shape 101c of the main assembly driving shaft 101 is within the range of the driving force receiving surface 73a, in a state where the abutment portion 76b and the semispherical shape 101c are in contact.

[0294] In this embodiment, the coupling member 28 is an integral member. However, for example, the coupling member 28 may comprise two members by making the aligning portion 76 unintegral with other portions. The coupling member 28 may be constituted by combining three or more separate members by constituting the other portion by a plurality of members.

[Mounting of Cartridge to Main Assembly of Image Forming Apparatus]

[0295] With reference to FIGS. 16 and 17, mounting and dismounting of the process cartridge 7 relative to the image forming apparatus main assembly will be described.

[0296] FIG. 16 is a perspective view illustrating the mounting of the cartridge 7 to the image forming apparatus main assembly 100A.

[0297] FIG. 17 is cross-sectional views illustrating the mounting operation of the cartridge 7 to the image forming apparatus main assembly 100A.

[0298] The image forming apparatus main assembly 100A of this embodiment employs a structure capable of mounting the cartridge in a substantially horizontal direction. Specifically, the image forming apparatus main assembly 100A has an inside space in which a cartridge can be mounted. The image forming apparatus main assembly has a cartridge door 104 (front door) for inserting the cartridge into the space, at the front side of the main assembly 100A (the side near the user standing in use).

[0299] As shown in FIG. 16, the cartridge door 104 of the image forming apparatus main assembly 100A is provided so as to be opened and closed. When the cartridge door 104 is opened, the lower cartridge guide rail 105 for guiding the cartridge 7 is provided on the bottom surface defining the space, and the upper cartridge guide rail 106 is provided on the upper surface. The cartridge 7 is guided to the mounting position by the upper and lower guide rails (105, 106) provided above and below the space. The cartridge 7 is inserted into the mounting position substantially along the axis of the photosensitive drum unit 30.

[0300] The mounting and dismounting operations of the cartridge to the image forming apparatus main assembly 100A will be described below Referring to FIG. 17.

[0301] As shown in part (a) of FIG. 17, the drum unit bearing member 39R or the photosensitive drum 1 does not contact the intermediary transfer belt 5 at the start of insertion of the cartridge 7. In other words, the size relationship is such that the photosensitive drum 1 and the intermediary transfer belt 5 do not contact with each other in a state in which the end portion on the rear side with respect to the inserting direction of the cartridge 7 is supported by the lower cartridge guide rail 105.

[0302] As shown in part (b) of FIG. 17, the image forming apparatus main assembly 100A includes a rear side lower cartridge guide 107 projecting upward with respect to the direction of gravity from the lower cartridge guide rail 105 toward the rear side in the inserting direction of the lower cartridge guide rail 105. The rear cartridge lower guide 107 is provided with a tapered surface 107a on the front side with respect to the inserting direction of the cartridge 7. Along with the insertion, the cartridge 7 rides on the tapered surface 107a and is guided to the mounting position.

[0303] The position and the shape of the rear cartridge lower guide 107 may be any if a part of the cartridge does not rub the image forming area 5A of the intermediary transfer belt 5 when the cartridge is inserted into the apparatus main assembly 100A. Here, the image forming area 5A is a region where a toner image to be transferred onto the recording material 12 is carried on the intermediary transfer belt 5. Further, in this embodiment, of parts of the cartridges in the mounting attitude, the unit bearing member 39R provided on the rear side with respect to the inserting direction of the cartridge 7 most protrudes upward with respect to the direction of gravity. Therefore, it will suffice if the arrangement and the shape of each element are appropriately selected so that the trace (hereinafter referred to as insertion trace) of the end of the drum unit bearing member 39R farthest in the inserting direction at the time of the insertion Of the cartridge does not interfere with the image forming area 5A.

[0304] Thereafter, as shown in part (c) of FIG. 17, the cartridge 7 is further inserted to the rear side of the image forming apparatus main assembly 100A from the state in which it is on the rear side cartridge lower guide 107. Then, the drum unit bearing member 39R abuts to the rear cartridge positioning portion 108 provided in the image forming apparatus main assembly 100A. At this time, the cartridge 7 (the photosensitive drum unit 30) is inclined by about 0.5 to 2 degrees relative to the state in which the cartridge 7 (photosensitive drum unit 30) is completely mounted in the image forming apparatus main assembly 100A (part (d) of FIG. 17). That is, in the inserting direction of the cartridge 7, the downstream side of the cartridge 7 (photosensitive drum unit 30) is at an upper level than the upstream side.

[0305] Part (d) of FIG. 17 is an illustration of the state of the apparatus main assembly and the cartridge when the cartridge door 104 is closed. The image forming apparatus 100A has a near side cartridge lower guide 109 on the front side, with respect to the inserting direction, of the lower cartridge guide rail 105. The front side cartridge lower guide 109 is configured to move up and down in interrelation with the opening and closing of the cartridge door (front door) 104.

[0306] When the cartridge door 104 is closed by the user, the front side cartridge lower guide 109 is raised. Then, the drum unit bearing member 39L and the near side cartridge positioning portion 110 of the image forming apparatus main assembly 100A are brought into contact to each other, so that the cartridge 7 is positioned relative to the image forming apparatus main assembly 100A.

[0307] With the above-described operation, the mounting of the cartridge 7 to the image forming apparatus main assembly 100A is completed.

[0308] In addition, dismounting of the cartridge 7 from the image forming apparatus main assembly 100A is performed in the reverse order of the above-described inserting operation.

[0309] Because the oblique mounting structure is employed as described above, it is possible to suppress the rubbing between the photosensitive drum and the intermediary transfer belt when the cartridge 7 is mounted on the apparatus main assembly 100A. For this reason, it is possible to suppress the occurrence of minute scratches (scratches) on the surface of the photosensitive drum or the surface of the intermediary transfer belt.

[0310] Further, the structure of this embodiment can simplify the structure of the image forming apparatus main assembly 100A as compared with the structure in which the entire cartridge is lifted up after the cartridge is horizontally moved and mounted to the apparatus main assembly.

[Engaging Process of Coupling Member with Main Drive Shaft]

[0311] Referring to FIGS. 18 and 19, the engagement process of the coupling member 28 and the main assembly driving shaft 101 will be described in detail.

[0312] FIG. 18 is a cross-sectional view illustrating a mounting operation of the coupling member 28 to the main assembly driving shaft 101.

[0313] FIG. 19 is sectional views illustrating the mounting operation of the coupling member 28 to the main assembly driving shaft 101 when the main assembly driving shaft 101 rotates from a state in which the phases of the main assembly drive transmission groove 101a and the engagement portion 73 (the drive force receiving surface 73a) are not aligned, to the state in which the phases are aligned.

[0314] Part (a) of FIG. 18 is an illustration of a state in which the coupling member 28 has started engaging with the main driving shaft 101. Part (e) of FIG. 18 illustrates a state in which the cartridge 7 is mounted to the image forming apparatus main assembly 100A. In particular, part (e) of FIG. 18 shows a state in which the front side lower cartridge guide 109 is raised as the cartridge door 104 is closed, and the cartridge 7 is positioned with respect to the image forming apparatus main assembly 100A.

[0315] part (b) of FIGS. 18 to 18 (d) are illustrations of a process of connecting the coupling member 28 to the main assembly driving shaft 101 between part (a) of FIG. 18 and part (e) of FIG. 18. The main assembly driving shaft 101 hangs downward in the direction of gravity by a very small angle due to its own weight.

[0316] FIG. 19 is an illustration of a state in which the phases of the main assembly drive transmission groove 101a and the engagement portion 73 (driving force receiving surface 73a) are not aligned.

[0317] As has been described with reference to part (b) of FIG. 17, the cartridge 7 rides on the rear lower cartridge guide 107. That is, the cartridge 7 is in a state of being inclined by about 0.5 to 2 degrees while gradually increasing the inclination until reaching the state of part (a) of FIG. 17 to part (b) of FIG. 17. Then, the cartridge 7 rides on the rear lower cartridge guide 107.

[0318] Similarly, as shown in part (a) of FIG. 18, the coupling member 28 is inserted into the main assembly driving shaft 101 in a state inclined by about 0.5 to 2 degrees as compared with the state when the cartridge 7 is positioned relative to the image forming apparatus main assembly 100A (as shown in part (e) of FIG. 18).

[0319] As shown in FIG. 6, the main assembly driving shaft 101 is cantilevered at the borne portion 101d. Further, the gear portion 101e is in meshing engagement with a gear (not shown) for transmitting the drive to the gear portion 101e. Part (a) of FIG. 18 in an illustration of the state in which the main assembly driving shaft 101 does not abut to the coupling member 28. In this state, the bearing 7 it is slanted by θ1 degree in the direction determined by its own weight and the meshing direction about the borne portion 101d, as compared with the state in which the cartridge 7 is positioned relative to the image forming apparatus main assembly 100A (shown in part (e) of FIG. 18).

[0320] As shown in part (b) of FIG. 18, the tip of the inner peripheral surface 71b of the cylindrical portion 71 of the coupling member 28 first abuts against the rough guide portion 101g of the main assembly driving shaft 101. As shown in the Figure, the main assembly driving shaft 101 is configured to be cantilevered at a borne portion 101d. Therefore, the rough guide portion 101g of the main assembly driving shaft 101 is inserted in a state in which it is fitted to the inner peripheral surface 71b of the coupling member 28. As described above, in the Z direction, the engaging portion 73 is provided such that a length L1 from the front end surface of the cylindrical portion 71 to the front end surface of the engaging portion 73, and the length L2 of the driving force receiving surface 73 satisfy L1>L2 (as shown in FIG. 13). Therefore, before the semispherical shape 101c at the free end of the main assembly driving shaft 101 hits the engaging portion 73, the rough guide portion 101g of the main assembly driving shaft 101 follows the inner peripheral surface 71b of the coupling member 28. As a result, the main assembly driving shaft 101 is guided by the coupling member 28, so that the semispherical shape portion 101c at the free end of the main assembly driving shaft 101 is prevented from hitting an unintended portion of the engaging portion 73 or the base portion 74. This is effective to protect the engaging portion 73 and the indicating portion 74.

[0321] As shown in part (c) of FIG. 18, when the coupling member 28 is further inserted toward the back side of the main driving shaft 101, the insertion taper surface 73d of the engagement portion 73 and the main driving shaft 101 and the semispherical shape 101c abut to each other. Due to the inclined surface of the insertion tapered surface 73d and the spherical shape of the semispherical shape 101c, the main assembly driving shaft 101 is guided substantially to the center of the three engaging portions 73.

[0322] When the coupling member 28 is inserted further into the main assembly driving shaft 101, the base portion 74 elastically deforms radially outward so that the engaging portion 73 follows the semispherical shape 101c. As a result, as shown in part (a) of FIG. 19, the engaging portion 73 moves (retracts) to the outer diameter surface of the shaft portion 101f of the main assembly driving shaft 101. By this movement, as shown in part (d) of FIG. 18, the coupling member 28 is mounted to the main assembly driving shaft 101 until the dismounting tapered surface 73e of the engagement portion 73 comes deeper in the Z direction than the main assembly side dismounting taper 101i of the main assembly driving shaft 101.

[0323] Thereafter, as described above, the cartridge 7 is lifted so that the drum unit bearing member 39L of the cartridge 7 hits the front side cartridge positioning portion 110. By thus lifting the cartridge 7, the cartridge 7 is positioned relative to the image forming apparatus main assembly 100A (as shown in part (d) of FIG. 17). By this operation of the cartridge 7, as shown in part (e) of FIG. 18, the inclination of the coupling member 28 is eliminated.

[0324] When the main assembly driving shaft 101 rotates, as shown in part (b) of FIG. 19, the main assembly drive transmission groove 101a and the engagement portion 73 come to have the same phase. As a result, the elastic deformation of the base portion 74 is eliminated, a part of the engagement portion 73 enters the main assembly drive transmission groove 101a, and the coupling member 28 and the main assembly driving shaft 101 are engaged with each other.

[0325] When the phases of the main assembly drive transmission groove 101a and the engagement portion 73 are aligned, the elastic deformation of the base portion 74 is released at the stage of part (d) of FIG. 17, and the state becomes as shown in part (b) of FIG. 19, so that the main assembly driving shaft 101 can transmit the driving force to the cartridge 7 via the coupling member 28.

[0326] As described above, as the cartridge 7 is mounted in the apparatus main assembly 100A, the main assembly drive transmission groove 101a and the engagement portion 73 can be engaged with each other. Therefore, there is no need to move the main assembly driving shaft 101 to engage with the coupling member 28. That is, there is no need to provide a mechanism for moving the main assembly driving shaft 101 so as to engage with the coupling member 28, in the apparatus main assembly 100A of the image forming apparatus. In the conventional structure, there is provided a mechanism for moving the main assembly driving shaft 101 so as to engage with the coupling member 28 after mounting the cartridge 7 to the image forming apparatus main assembly 100A. However, in this embodiment, such a mechanism can be omitted from the apparatus main assembly 100A.

[0327] When the cartridge 7 is mounted on the apparatus main assembly 100A, the engaging portion 73 of the coupling member 28 contacts with the main assembly driving shaft 101 to retreat radially outward. The engaging portion 73 is configured to engage with the groove (main assembly drive transmission groove 101a) of the main assembly driving shaft 101 by moving radially inward.

[0328] Here, it is also possible to provide a groove for receiving the drive on the coupling member, and a movable portion engageable with the groove by moving in the radial direction is provided on the main assembly driving shaft 101 side. However, as compared with the cartridge 7, the image forming apparatus main assembly 100A is required to have higher durability. It is preferable to provide the movable portion (the engaging portion 73) that moves in the radial direction on the side of the coupling member 28 of the cartridge 7 as in this embodiment, from the standpoint of the durability of the image forming apparatus main assembly 100A.

[Removal of Coupling Member from Main Driving Shaft]

[0329] Referring to FIG. 20, the removal operation of the coupling member 28 from the main driving shaft 101 will be described.

[0330] FIG. 20 is a cross-sectional view illustrating the removal operation of the coupling member 28 from the main assembly driving shaft 101.

[0331] As shown in part (a) of FIG. 20, the drive force receiving surface 73a and the main assembly drive transmission surface 101b are in contact with each other at the time when the rotation drive of the main assembly driving shaft 101 is stopped. In this state, a part of the engagement portion 73 enters the main assembly drive transmission groove 101a.

[0332] When the cartridge door 104 is opened, the lower front side cartridge guide 109 lowers, and the drum unit bearing member 39L separates from the front side cartridge positioning portion 110 of the image forming apparatus main assembly 100A. At this time, as shown in part (b) of FIG. 20, the coupling member 28 and the main assembly driving shaft 101 are inclined by about 0.5 to 2 degrees with respect to the angle at the mounting complete state (Z direction).

[0333] When the cartridge 7 is started to be removed from the image forming apparatus main assembly 100A, as shown in part (c) of FIG. 20, the dismounting tapered surface 73e of the engaging portion 73 abuts to the main assembly side dismounting taper 101i. When the dismounting tapered surface 73e abuts to the main assembly side dismounting taper 101i, the base portion 74 begins to elastically deform and moves the engaging portion 73 outwardly in the radial direction along the main assembly side dismounting taper 101i.

[0334] Further, when the coupling member 28 is removed from the main assembly driving shaft 101, the state is the same as shown in part (a) of FIG. 19, and the base portion 74 is further elastically deformed and the engagement portion 73 is inserted into the shaft portion 101f of the main assembly driving shaft 101. By moving the engaging portion 73 to the outer diameter surface of the shaft portion 101f, the coupling member 28 can be removed from the main assembly driving shaft 101 as shown in part (d) of FIG. 20.

[0335] Further, when the coupling member 28 is removed from the main assembly driving shaft 101, as shown in part (e) of FIG. 20, the elastic deformation of the base portion 74 is released and the position of the engagement portion 73 returns to the position before the elastic deformation.

[0336] With the above-described operation, the coupling member 28 can be removed from the main assembly driving shaft 101.

[0337] In this embodiment, as shown in FIG. 12, the base portion 74 and the U-shaped cut-away portion 71d are arranged on the Z1 direction downstream side of the engagement portion 73, but as shown in FIG. 21, the engagement portion 73 may be arranged in the Z1 direction downstream side of the base portion 74 and the U-shaped cut-away portion 71d. It may be selected appropriately depending on the arrangement of the main assembly driving shaft 101 and the coupling member 28 in the image forming apparatus main assembly 100A.

[0338] By using the coupling member 28 and the main assembly driving shaft 101 of this embodiment, it is possible to omit a mechanism for moving the main assembly driving shaft 101. In other words, in this embodiment, the coupling member 28 is provided at a position where the coupling member 28 is engageable with the main assembly driving shaft 101 when the cartridge 7 is mounted to the image forming apparatus main assembly 101A. Therefore, it is unnecessary to move the main assembly driving shaft 101 relative to the coupling member 28 so that the coupling member 28 and the main assembly driving shaft 101 can be brought into engagement with each other.

[0339] Further, by using the coupling member 28 of this embodiment, the engaging portion 73 and the base portion 74 are not exposed at the outer surface of the cartridge 7. By this, the engaging portion 73 and the base portion 74 can be protected.

[0340] In this embodiment, the entirety of the driving force receiving portion 73a and the supporting portion thereof (the engaging portion 73 and the base portion 74) is arranged inside the bearing portion of the drum unit bearing member 39R in the axial direction. However, if at least a part of the driving force receiving portion 73a and the supporting portion thereof (the engaging portion 73 and the base portion 74) is arranged inside the bearing portion of the bearing member 39R in the axial direction, the engaging portion 73 and the base portion 74 can be protected. In addition, even if the bearing portion is disposed so as to overlap with the driving force receiving portion 73a and the supporting portion thereof (the engaging portion 73 and the base portion 74) in the axial direction, the driving force receiving portion 73a and the supporting portion thereof are protected.

[0341] That is, when the bearing portion, the engaging portion 73, and the base portion 74 are projected onto the axis of the coupling member, the projection areas of the engaging portion 73.

[0342] The driving force receiving portion 73a, and the base portion 74 may overlap with the projection area of the bearing portion.

[0343] Referring to FIGS. 22, 23, 24, 25, 26, and 27, Embodiment 2 will be described.

[0344] FIG. 22 is a cross-sectional perspective view of the coupling member 228 according to Embodiment 2.

[0345] FIG. 23 is a perspective view of the coupling member 228 according to Embodiment 2.

[0346] FIG. 24 is a illustration of the coupling member 228 according to Embodiment 2 as viewed in the Z direction from the inner side.

[0347] FIG. 25 is a sectional view illustrating the operation of mounting the coupling member 228 to the main assembly driving shaft 101 according to Embodiment 2.

[0348] FIG. 26 in an illustration of the coupling member 228 according to Embodiment 2 as viewed from the outer side in the Z direction.

[0349] Elements corresponding to those of Embodiment 1 are assigned the same names. For them, detailed explanation will be given in detail regarding the constitution and action and the like which are different from the elements described in the foregoing, and explanations on the same points as those described in the foregoing may be omitted in some cases.

[0350] In this embodiment, at least a part of a support portion (the engaging portion 273 and the base portion 274) movably supporting the driving force receiving portion 273a is arranged inside the photosensitive drum 1. In particular, the fixed end of the support portion (that is, the base portion 274a of the base portion 74) is disposed inside the photosensitive drum 1 (FIG. 25). Details will be described below.

[0351] In this embodiment, a coupling member 228 is provided as a flange member mounted to an end portion on the driving side of the cylinder (photosensitive drum 1). The coupling member 228 has an engaging portion 273 configured to engage with the main assembly driving shaft 101 and a base portion 274 for supporting the engaging portion 273.

[0352] The engaging portion 273 is provided with a driving force receiving surface 273a. The driving force receiving surface 273a is a driving force receiving portion (driving force receiving portion) which can receive a driving force (rotational force) for rotating the photosensitive drum 1 from the outside of the cartridge (outside of the drum unit), that is, from the apparatus main assembly.

[0353] The engaging portion 273 and the base portion 274 are support portions for supporting the driving force receiving surface (driving force receiving portion) 273a.

[0354] In Embodiment 1, the cylindrical portion 71 is provided with a cut-away portion 71d, and the base portion 74 extends from the cylindrical portion 71. The base portion 74 has a shape arranged between the borne portion 71c and the mounting portion 72 in the Z direction.

[0355] The case will be considered in which the apparatus with the cartridge is kept unoperated for a long period in a state that the phases of the drive transmission groove 101a of the main assembly driving shaft 101 and the engagement portion 73 of the coupling member 28 do not match (shown in part (a) of FIG. 19). In such a case, not only the base portion 74 but also the neighborhood of the root portion 74a of the base portion 74 of the cylindrical portion 71 may creep-deforms.

[0356] Here, the alignment precision between the borne portion 71c and the press-fitted portion 72d is kept high so that the axis of the borne portion 71c and the axis of the press-fit portion 72d of the mounting portion 72 are coaxial. However, even in this case, the amount of creep deformation in the neighborhood of each root portion 74a of the cylindrical portion 71 is not necessarily even. Therefore, if the neighborhood of the root portion 74a of the base portion 74 therebetween is also creep-deformed, there is a liability that the coaxiality accuracy of alignment for keeping the central axis of the borne portion 71c and the central axis of the press-fit portion 72d is deteriorated.

[0357] If the coaxial accuracy of the axis of the borne portion 71c and the axis of the press-fit portion 72d decreases, there is a possibility that the coaxial accuracy of the axis of the borne portion 71c and the axis of the photosensitive drum 1 also deteriorate. As a result, the rotation precision of the photosensitive drum 1 is also deteriorated, with the result of liability that the image quality may be adversely affected.

[0358] Under the circumstances, in this embodiment, the base portion 274 has a shape extending from the inner circumferential cylinder 272h of the mounting portion 272 toward the engagement portion 273 outwardly in the axial direction of the coupling member 228. That is, the base portion 274 is an extension (extending portion, extension portion) extending at least in the axial direction. The engaging portion 273 is a projection (protrusion, protrusion) supported by the base portion 274.

[0359] The mounting portion 272 is a cylindrical portion having a plurality of ribs around the periphery thereof but is a substantially cylindrical, and it is a portion (inner circumferential contact portion, fixed portion) to be fixed in contact with the inner circumference of the photosensitive drum 1. Further, a cylindrical portion 271 is provided on the outer side of the mounting portion 272 with respect to the axial direction.

[0360] The projecting direction of the engaging portion 273 crosses with the extending direction in which the base portion 274 extends. Further, the engaging portion 273 projects at least toward the inner side in the radial direction of the coupling member.

[0361] Similarly to Embodiment 1, the engaging portion 273 is provided with a driving force receiving portion for receiving the driving force from the outside (namely the driving shaft 101) outside the drum unit 30. The engaging portion 273 and the base portion 274 are support portions which support the driving force receiving portion 273a so as to be movable at least in the radial direction of the coupling member. In more detail, the base portion 274 deforms with its fixed end as a fulcrum point, so that the driving force receiving portion 273a is movable at least in the radial direction of the coupling member.

[0362] The inner peripheral cylinder 272h is an inner diameter portion of the mounting portion 272 and has a cylindrical shape.

[0363] By providing the base portion (rear end) 274a of the base portion 274 in the inner tube cylinder 272h, even if the neighborhood of the root portion 274a of the base portion 274 is creep-deformed, the influence extending to the borne portion 271c of the cylindrical portion 271 can be suppressed. That is, the outer peripheral portion (press-fit portion 272d) of the mounting portion 272 is covered with the photosensitive drum 1, and therefore, the mounting portion 272 is hardly deformed. Therefore, even if the root 274a of the base portion 274 is temporarily deformed, the deformation of the mounting portion 272 itself connected with the base portion 274 is suppressed. As a result, the deformation of the entire coupling member 228 is suppressed, so that the deformation of the borne portion 271c provided on the free end side of the coupling member 228 can also be suppressed.

[0364] Further, by mounting the base portion 274 to the mounting portion 272 which is difficult to be deformed, it is possible to suppress deformation and tilting of the base portion 274. That is, by disposing the base 274a of the base portion 274 on the inner circumference cylinder 272h of the mounting portion 272, it is possible to suppress the tilting of the root portion 274a. For this reason, it is contributable to the stable rotation of the photosensitive drum 1, when the coupling member 228 receives the driving force from the main assembly driving shaft 101.

[0365] If the difference between the outer diameter of the press-fit guide portion 272f and the inner diameter of the inner peripheral cylinder 272h is not sufficiently large, both the press-fit guide portion 272f and the inner peripheral cylinder 272h may not be circular in some cases. At this time, the press-fit guide portion 272f may have a shape of a plurality of ribs radially arranged as in this embodiment. Even with such a shape, the press-fit portion 272d can be stably press-fitted into the photosensitive drum 1.

[0366] In addition, in this embodiment, as shown in FIG. 23, a plurality of ribs are radially arranged on the outer peripheral portion of the mounting portion 272, and these ribs are press-fit guide portions 272f. As shown in FIG. 24, the root portion 274a of the base portion 274 is disposed at a position corresponding to the plurality of ribs forming the press-fit guide 272f. Thus, when the driving force is received from the main assembly driving shaft 101, the driving force is transmitted from the root portion 274a to the press-fitting portion 272d through the ribs, so that deformation of the inner circumferential cylinder 272h due to the driving force can be further suppressed.

[0367] As shown in FIG. 25, when the root portion 274a of the base portion 274 is provided in the mounting portion 272, the root portion 274a is disposed inside the photosensitive drum (drum cylinder) 1. That is, the base 274 and the photosensitive drum 1 are projected onto the axis Ax of the photosensitive drum 1 (=the axis of the coupling member 228). Then, a part of the projection area A274 of the base portion 274 (the projection area on the side of the base 274a) overlaps with a part of the projection area A1 of the photosensitive drum 1 on the axis.

[0368] In the case that “A is inside the photosensitive drum 1”, An is the interior of the photosensitive drum both when the photosensitive drum is viewed along the axis Ax and when the photosensitive drum is viewed in the direction perpendicular to the axis Ax.

[0369] In this embodiment, the base 274 is disposed so that a part of the area on the side of the base 274a overlaps with the area of the photosensitive drum 1, but the base 274 may be disposed so that the whole of the base 274 overlaps the photosensitive drum 1. In other words, the entire base portion 274 may be disposed inside the photosensitive drum 1. Such a structure will be described hereinafter with respect to Embodiment 3 (FIG. 28).

[0370] The engaging portion 273 will be described. As shown in FIGS. 22 and 25, a taper 273f is provided on the outer diameter side of the engaging portion 273. As in Embodiment 1, also in this embodiment, when the phases of the drive transmission groove 101a of the main assembly driving shaft 101 and the engagement portion 273 are not aligned each other, the base portion 274 deforms and the engagement portion 273 moves radially outward. Since the engaging portion 273 avoids hitting the main assembly driving shaft 101 by this retracting operation, the coupling member 228 can be mounted to the main assembly driving shaft 101. When the coupling member 228 is mounted to the main assembly driving shaft 101, the dismounting tapered surface 273e of the engaging portion 273 moves to the rear side in the Z direction from the main assembly side dismounting taper 101i of the main assembly driving shaft 101.

[0371] In the process of mounting the coupling member 228 to the main assembly driving shaft 101, the radially outward movement amount of the engagement portion 273 increases as the distance from the base portion 274a of the base portion 274 increases. In the absence of the taper 273f, when the retraction amount of the engaging portion 273 is large, the engaging portion 273 interferes with the inner peripheral surface 271b of the cylindrical portion 271 as indicated by the dotted line in part (a) of FIG. 25. Therefore, by providing the taper 273f, the engaging portion 273 is prevented from interfering with the inner peripheral surface 271b of the cylindrical portion 271 even if the engaging portion 273 moves largely in the radial direction. As a result, the outer diameter D5 of the shaft portion 101f of the main assembly driving shaft 101 can be maximized.

[0372] The distance between the base portion 274 and the inner surface (the inner circumferential surface 271b) of the coupling member 228 increases as it goes from the rear end to the free end in a state (natural state) in which the elastic deformation is eliminated.

[0373] Thereafter, similarly to Embodiment 1, as shown in part (b) of FIG. 25, by the rotation of the main assembly driving shaft 101, when the phase of the drive transmission groove 101a and the engagement portion 273 are aligned, the elastic deformation of the base portion 274 It is released. Then, the engagement portion 273 moves inwardly in the radial direction to enter the drive transmission groove 101a. The drive can be transmitted from the main assembly driving shaft 101 to the coupling member 228 by way of the engagement portion 273.

[0374] Similarly to Embodiment 1, as shown in FIGS. 22 and 26, the aligning portion 276 has a radial direction positioning portion 276a. The radial direction positioning portion 276a is disposed at a position overlapping with the engaging portion 273 in the Z direction (axial direction). That is, when the radial direction positioning portion 276a and the engaging portion 273 are projected onto the axis line of the coupling member 228 (the axis line of the photosensitive drum 1), the projection area of the radial direction positioning portion 276a and the projection area of the engaging portion 273 at least partly overlaps with each other.

[0375] On the other hand, the radial direction positioning portion 276a is disposed at a position out of the engaging portion 273 as viewed along the axial direction of the coupling member 228. FIG. 24 is an illustration of the coupling member 228 as viewed along the axial direction. As can be seen from this Figure, the radial direction positioning portion 276a does not overlap with the engaging portion 273, and a certain amount of clearance is provided between them. Such an arrangement relationship is mainly due to the reason in manufacturing the coupling member 228. Details will be described hereinafter.

[0376] Further, as shown in FIGS. 22 and 25 (b), the aligning portion 276 has an abutment portion 276b. When the drive of the main assembly driving shaft 101 is transmitted to the coupling member 228, the abutment portion 276b abuts against the semispherical semispherical shape 101c at the free end of the main assembly driving shaft 101. By this, the position of the coupling member 228 in the axial direction is determined relative to the main assembly drive 101.

[0377] Referring to FIG. 28, a Embodiment 3 will be described.

[0378] FIG. 28 is a cross-sectional view of the coupling member (flange member) 328 and the main assembly driving shaft 101 taken along the rotation center line (rotation axis) according to the Embodiment 3.

[0379] Elements corresponding to those of the above-described embodiment (particularly, Embodiment 2) are denoted by the same names, and descriptions of the similar points to the above-described elements may be omitted. The description will be made mainly on differences from the elements described above.

[0380] In this embodiment, the entirety of the driving force receiving portion 373a and supporting portions (the engaging portion 373 and the base portion 374) movably supporting the driving force receiving portion 373a is disposed inside the photosensitive drum 1.

[0381] The coupling member 328 of this embodiment has an engaging portion 373 for engaging with the main assembly driving groove 101a and a base portion 374 for supporting the engaging portion. The base portion 374a is connected to the inner peripheral cylinder 372h of the flange member so that the base portion 374 is supported by the coupling member 328.

[0382] The engaging portion 373 is provided with a driving force receiving portion which is in contact with the main assembly driving groove 101a and receives the driving force from the main assembly driving groove 101a. The shapes of the engaging portion 373 and the driving force receiving portion thereof are the same as those of the engaging portion 273 and the driving force receiving portion 273a of Embodiment 2, and therefore the detailed description thereof will be omitted.

[0383] The engaging portion 373 is a projecting portion (protruding portion) supported by the base portion 374. The engaging portion 373 projects at least radially inward of the coupling member. The base portion 374 is an extension (extending portion, extended portion) extending in a direction crossing with the projecting direction of the engaging portion 373. The base portion 374 is also a deformable portion (elastically deformable portion, flexible portion) configured to be elastically deformable.

[0384] The engaging portion 373 is provided with a driving force receiving portion, and the engaging portion 373 and the base portion 374 are support portions movably supporting the driving force receiving portion.

[0385] In Embodiment 2, as shown in FIGS. 22 and 25, the engaging portion 273 is provided inside the cylindrical portion 272 in the Z direction.

[0386] On the other hand, in this embodiment, the engaging portion 373 is formed inside the mounting portion 372 in the Z direction. Here, the mounting portion 372 is a portion pressed into the inner periphery of the photosensitive drum 1 and mounted to the photosensitive drum 1. Therefore, the engaging portion 373 and the driving force receiving portion are positioned inside the photosensitive drum 1. More specifically, when the photosensitive drum 1 and the engaging portion 373 are projected onto the axis of the photosensitive drum 1, an area of the photosensitive drum 1 and an area of the engaging portion 373 (period of the driving force receiving portion of the engaging portion 373) are overlapped with each other. More specifically, all the area of the engaging portion 373 (driving force receiving portion) is included in the area of the photosensitive drum 1.

[0387] By employing such a shape, it is possible to dispose the photosensitive drum 1 closer to the main driving shaft 101 side (the Z1 direction side) than in Embodiment 2 in the Z direction. Therefore, it is contributable to miniaturization of the cartridge 7 and the image forming apparatus 100 in the Z direction. Or, parts of the engaging portion 373 and the base portion 374 can be provided at the back side of the photosensitive drum 1 which is hard to be touched by the user, and therefore, these members can be protected.

[0388] It is preferable that the entire engaging portion 373 is disposed inside the photosensitive drum 1. However, if at least a part of the engaging portion 373 (driving force receiving portion) is inside the photosensitive drum 1, the above-mentioned effect is provided. That is, it will suffice if when the photosensitive drum 1 and the engaging portion 373 are projected onto the axis of the photosensitive drum 1, the area of the photosensitive drum 1 and the area of the engaging portion 373 (the area of the driving force receiving portion) on the axis are at least partly overlapped with each other.

[0389] The base portion 374 is also located inside the photosensitive drum 1. That is, when the photosensitive drum 1 and the base portion 374 are projected onto the axis of the photosensitive drum 1, the projection area of the photosensitive drum 1 and the projection area of the base portion 374 overlap each other.

[0390] The fourth example (Embodiment 4) will be described. This embodiment is a modification of the structure of Embodiment 2. Therefore, prior to the description of this embodiment, the features of the coupling member 228 shown in Embodiment 2 will be described again.

[0391] In the Embodiment 2, the coupling member 228 has a shape with which the base portion 274 extends in the axial direction of the coupling member 228 from the inner peripheral cylinder 272h of the mounting portion 272 toward the engagement portion 273 (FIG. 25).

[0392] Also, when the coupling member 228 is projected onto the projection plane perpendicular to the axis of the coupling member 228, the aligning portion 276 and the like are arranged so that the following relationship is satisfied. That is, in the projection plane, the aligning portion 276 does not overlap the engaging portion 273, the base portion 274, or the region 1 mm around the engaging portion 273 and the base portion 274. In other words, when the coupling member 228 is viewed along the axis, there is a gap (clearance) of about 1 mm between the aligning portion 276 and the engaging portion 273, and there is also a gap (clearance) of about 1 mm between the aligning portion 276 and the base portion 274A.

[0393] The reason why the coupling member 228 has the above-described structure is that the coupling member 228 is manufactured through the following manufacturing method. (Description of Manufacturing Method).

[0394] The coupling member 228 of Embodiment 2 is manufactured by an injection molding (insert molding) using a mold.

[0395] Referring to FIG. 27, a structure of a metal mold used for molding the coupling member 228 will be described.

[0396] The coupling member 228 has a shape with which the flange portion 275 protrudes outward in the radial direction. In the case of molding such a shape, it is preferable that the metal mold is as shown in FIG. 27.

[0397] Specifically, as shown in the Figure, the metal mold has a two-piece structure including a left mold (cylindrical mold 60) and a right mold (mounting part mold 61). By aligning the right and left molds, a space portion (mold cavity, hollow portion) having the same shape as the molded product is formed. The material is poured into this space portion and solidified in the mold, whereby the coupling member 228 is provided. The mold has a structure in which a mold parting plane 62 (a plane along which the mold is divided, a plane at which the mold halves are contacted), which is a portion for fitting the right and left molds, is disposed in the neighborhood of the space forming the flange portion 275. The cylindrical mold 60 has a shape including a space for molding the outer periphery of the cylindrical portion 271. Similarly, the mounting portion side mold 61 has a shape having a space for molding the mounting portion 272.

[0398] In the case that the coupling member 228 is molded using such a metal mold, it is preferable to use a thermoplastic resin from the standpoint of mass productivity. More particularly, materials such as POM and PPS are considered to be preferable. However, in order to satisfy requirements such as strength, other materials may be appropriately selected. Specifically, a thermosetting resin or a metallic material may be used.

[0399] As described in the foregoing, the engaging portion 273 has an insertion taper 273d at one end in the Z direction and a dismounting taper 273e at the other end. Therefore, it is difficult to provided the mold parting plane 62 at either end face of the engaging part 273 with respect to the Z direction. This is because, in the case of using a mold divided into two parts, if the mold parting plane 62 is arranged on one of the two end faces of the engaging portion 273, it is difficult to remove the molded coupling member 228 from the mold. That is, at the time of detaching the two molds from the engaging portion 273 after the engaging portion 273 is molded, at least one of the molds is caught by the engaging portion 273 and can not be moved.

[0400] Therefore, when molding the coupling member 228 of this embodiment, the mold parting plane 62 is determined as follows. That is, in the Z direction, a region from the driving force receiving surface 273a to the radially inner side of the base portion 274 is formed by the mounting portion side mold 61. Further, a region from the insertion taper 273d to the radially outer side of the base portion 274 is formed by the cylindrical mold 60. For this reason, it is necessary for the aligning portion 276 to be shaped so as not to interfere with the cylindrical mold 60 and the mounting portion side mold 61.

[0401] Specifically, when looking at the coupling member 228 along the Z direction, the aligning portion 276 does not overlap with the drive moving portion 273 and the base portion 274 in the range of about 1 mm around them (does not overlap) (As shown in FIG. 26).

[0402] As a result, a gap exists between the engaging portion 273 and the aligning portion 276, and a gap is generated between the base portion 274 and the aligning portion 276. Due to these gaps, the base portion 274 and the engaging portion 273 can move to a certain extent in the circumferential direction of the coupling member 228. In such a structure, it is desirable to increase the rigidity of the base 274. This is because if the rigidity of the base portion 274 is low by using a material that can not exhibit sufficiently high rigidity of the base portion, the following liability may arise.

[0403] In FIG. 29, as a reference example, a structure in which the material of the coupling member 228 is changed to one having low rigidity is shown.

[0404] FIG. 29 is a longitudinal sectional view illustrating the deformation of the base portion and the engaging portion by cutting the coupling member not using Embodiment 4 along the rotation center line (rotation axis).

[0405] In this embodiment, when the driving force receiving surface 3273a abuts to the main assembly driving force transmitting surface 101b, the cleaning blade 26, the charging roller 22, and the like apply a load to the photosensitive drum unit 3230. Due to this load, the is a liability that when the drive transmission force is received by the engagement portion 3273 from the main assembly driving shaft 101 as indicated by a arrow in FIG. 29, the base portion 3274 tilts downstream in the rotational direction from the root portion 3274a as a fulcrum point by the driving force. The engaging portion 3273 is disposed on the free end side of the base portion 3274, and therefore, when the base portion 3274 tilts, the engaging portion 3273 also tilts by the amount corresponding to the tilting of the base portion 3274. As a result, there is a likelihood that the driving force receiving surface 3273a and the main assembly driving force receiving surface 101a are not in contact with each other and the photoconductive drum unit 3230 can not be retracted to the borne portion 101d side of the main assembly bearing shaft 101.

[0406] Further, when the load applied by the cleaning blade 26, the charging roller 22, or the like described above varies, the rotation amount of the photosensitive drum 1 changes due to the change in the amount of inclination of the base portion 3274, and the image quality may be adversely affected.

[0407] Therefore, in Embodiment 2, a member having high rigidity is selected as the material of the coupling member 228 so that the likelihood described with reference to the reference example can be avoided, and the rigidity of the base portion 274 is maintained.

[0408] On the other hand, in this embodiment (Embodiment 4), unlike Embodiment 2, as shown in FIG. 30, of the gaps between the engaging portion 473 and the aligning portion 476, a backup portion 434a of the backup member 434 is inserted the gap upstream in the rotational direction of the engaging portion 473. By this, even if the rigidity of the base portion 474 is low, the tilt amount of the base portion can be kept small.

[0409] Hereinafter, Referring to FIGS. 30 to 38, details of the structure of this embodiment will be described.

[0410] FIG. 30 in an illustration of the coupling member 428 according to Embodiment 4 as viewed in the Z direction from the outer side.

[0411] FIG. 31 is a illustration of the flange member 470 according to Embodiment 4 as viewed in the Z direction from the outer side.

[0412] FIG. 32 is a longitudinal sectional view of the coupling member 428 according to Embodiment 4 taken along the rotation center line (rotation axis).

[0413] FIG. 33 is an illustration of the flange member 470 according to Embodiment 4 as viewed in the Z direction from the inner side.

[0414] FIG. 34 is a illustration of the backup member 434 according to Embodiment 4 as viewed in the Z direction from the outer side.

[0415] FIG. 35 is a longitudinal sectional view of the coupling member 428 according to Embodiment 4 and the main assembly driving shaft 101 taken along the rotation center line (rotation axis).

[0416] FIG. 36 is a perspective view illustrating the assembling of the backup member 434 to the flange member 470 according to Embodiment 4.

[0417] FIG. 37 is a cross-sectional view of the main assembly driving shaft 101 and the coupling member 428 according to Embodiment 4 taken along a plane perpendicular to the rotation axis and including at a position passing through a driving force receiving surface (driving force receiving portion) 473a.

[0418] FIG. 38 is a longitudinal sectional view of the coupling member 428 of another example according to Embodiment 4 and the main assembly driving shaft 101 taken along the rotation center line (rotation axis).

[0419] The coupling member 428 is formed by combining two parts, namely, a flange member 470 and a backup member 434.

[0420] In the flange member 470, the cylindrical portion 471, the mounting portion 472, the base portion 474, the engagement portion 473, the radial positioning portion 476a of the aligning portion 476, the receiving surface 476c, and the hooked portion 472b are disposed on the mounting portion 472. The receiving surface 476c and the engaging portion 473 are surfaces for sandwiching the backup portion 434a described later. The hooking portion 472b has a shape for fixing the backup member 434 to the flange member 470.

[0421] The engaging portion 473 is provided with a driving force receiving portion for receiving the driving force from the main assembly driving shaft 101 of the image forming apparatus main assembly. The engaging portion 473 and the base portion 474 are support portions for movably supporting the driving force receiving portion.

[0422] The flange member 470 is a driving force receiving member for receiving a driving force from the main assembly driving shaft 101 by way of a driving force receiving portion provided in the engaging portion 473.

[0423] In the backup member 434, a backup section 434a, a butting section 434b, and a press-fit section 434c are provided. The backup portion 434a is assembled into a gap in the upstream side with respect to the rotational direction of the engagement portion 473 of the gap between the engagement portion 473 and the aligning portion 476, and has a shape effective to suppress the tilting of the engagement portion 473 and the base portion 274. The abutment portion 434b has such a shape that a semispherical shape 101c at the free end of the main assembly driving shaft 101 abuts when driving of the main assembly driving shaft 101 is transmitted to the coupling member 428.

[0424] The press-fit portion 434c is so shaped as to fix the backup member 434 to the flange member 470 by being press-fitted into the mounting portion 472 of the flange member 470. (Description on Flange Member).

[0425] Referring to FIGS. 31, 32, and 33, the flange member 470 will be described.

[0426] As shown in FIG. 32, the mounting portion 472 of the flange member 470 has a hook portion 472b having a shape for mounting the backup member 434 to the flange member 470. The hooking portion 472b has a shape protruding from the inner peripheral surface 472h of the mounting portion 472, and as shown in FIG. 31, a plurality of the hooking portions 472b are disposed at phases different from the base portion 474 and the engaging portion 473 in the circumferential direction of the flange member 470. In this embodiment, the flange members 470 are arranged at three positions (120 degrees intervals, substantially equal intervals) at regular intervals in the circumferential direction of the flange member 470.

[0427] As shown in FIG. 32, the hooking portion 472b has, in the downstream side with respect to the Z1 direction, a surface substantially perpendicular to the Z shaft, and has, on the downstream side with respect to the Z2 direction, a taper shape to be used when assembling the backup member 434.

[0428] In addition, as the aligning portion 476 is viewed along the Z direction, the mounting portion 472 has a hole 476d in the range of about 1 mm around the mounting portion 472 (FIGS. 31, 32).

[0429] By providing the hole 476d and providing a gap of about 1 mm around the mounting portion 472, it is possible to manufacture the flange member 470 using a simple metal mold.

[0430] As shown in FIGS. 31 and 33, the aligning portion 476 has a receiving surface 476c. The backup portion 434a of the backup member 434 is sandwiched by a pinching surface 473g and the receiving surface 476c which are portions radially outward of the shaft portion 101f of the main assembly driving shaft 101 of the engaging portion 473. The sandwiching surface 473g and the receiving surface 476c are substantially parallel surfaces.

[0431] Further, as shown in FIG. 33, the aligning portion 476 has a rib 476e which is substantially perpendicular to the receiving surface 476c, an extended line thereof passes through the end of the pinching surface 473g on the shaft portion 101f side. (Description of backup member).

[0432] Referring to FIGS. 30, 34, 35, 36, the backup member 434 will be described.

[0433] The backup member 434 has a backup portion 434a, an abutment portion 434b, and a press-fit portion 434c.

[0434] As shown in FIG. 30, the back-up portion 434a is arranged so as to be assembled in a gap between the sandwiching surface 473g of each engaging portion 473 and the receiving surface 476c. The thickness is set to be approximately the same as the gap between the surface 473g and the receiving surface 476c. Further, as shown in FIG. 34, the circle connecting the ridge lines on the side of the sandwiching surface 473g of the backup portion 434a is disposed such that the center thereof is the same as the press-fitting portion 434c, and the diameter D8 thereof is approximately the same as the outer diameter D7 of the radial positioning portion 476a.

[0435] In the same manner as the abutment portion 76b of Embodiment 1, in the state that the abutment portion 434b abuts to the semispherical shape 101c, the center 101h of the semispherical shape 101c of the main assembly driving shaft 101 falls within the range of the driving force receiving surface 473a (FIG. 35).

[0436] The press-fit portion 434c is press-fitted into the inner peripheral cylinder 472h of the mounting portion 472 of the flange member 470. As shown in FIG. 35, the thickness of the press-fit portion 434c is set to be substantially the same as the gap between the vertical surface on the Z1 direction side of the hook portion 472b and the aligning portion 476 in the Z direction.

[0437] The backup member 434 having the above-described shape is assembled to the flange member 470 from the Z2 direction in the Z1 direction, thereby forming the coupling member 428 (shown in FIG. 36).

[Driving of Coupling Member by Main Assembly Drive Shaft]

[0438] Referring to FIG. 37, the transmission of rotational drive from the main driving shaft 101 to the coupling member 428 will be described.

[0439] When the driving force receiving surface 473a of the coupling member 428 abuts to the main assembly drive transmission surface 101b, the cleaning blade 26, the charging roller 22, and the like apply loads to the photosensitive drum unit 430. That is, the driving force receiving surface 473a rotates integrally with the driving transmission surface 101b while receiving the load (driving force) F1.

[0440] When this driving force F1 is received by the driving force receiving surface 473a, the driving force F1 is transmitted to the pinching surface 473g opposite to the driving force receiving surface 473a of the engaging portion 473 as shown in FIG. 37. The engaging portion 473 is backed up by the mounting portion 472 by way of the backup portion 434a, the receiving surface 476c, and the rib 476e, and therefore, the engaging portion 473 is not substantially deformed toward the downstream side in the rotational direction. As a result, the driving force receiving surface 473a can be stably brought into contact with the main assembly driving force receiving surface 101a, and the photosensitive drum unit 430 can be pulled toward the borne portion 101d side of the main assembly driving shaft 101. Even if the load F fluctuates, the engaging portion 473 is backed up as described above, since the engaging portion 473 is substantially not deformed, and therefore, the rotation amount of the photosensitive drum 1 does not substantially change, and the quality of the image quality can be maintained.

[0441] That is, the backup portion 434b is a member for restricting the driving force receiving portion provided in the engaging portion 474 from moving in the rotational direction of the drum unit (the circumferential direction of the coupling member).

[0442] In this embodiment, the engaging portion 473 (and the driving force receiving portion provided in the engaging portion 473) is provided inside the cylindrical portion 471 in the Z direction (FIG. 35). That is, the engaging portion 473 is located outside the photosensitive drum 1 in the Z direction. However, as shown in FIG. 38, even if the driving force receiving surface 473a (the engaging portion 473) is provided inside the mounting portion 72 in the Z direction, it is good similarly to Embodiment 3. At this time, similarly to the Embodiment 3, the photosensitive drum 1 can be arranged close to the main driving shaft 101 side. Therefore, it is possible to contribute to downsizing of the cartridge 7 and the image forming apparatus 100 in the Z direction. Or, the base portion and the engaging portion 473 can be protected by disposing a part of the base portion and the engaging portion 473 on the rear side of the photosensitive drum 1.

[0443] Referring to FIGS. 39 to 57, Embodiment 5 will be described.

[0444] In this embodiment, a support portion (engaging portion 573, base portion 574) movably supporting the driving force receiving portion 573a extends at least in the circumferential direction of the coupling member 528.

[0445] Elements corresponding to those of the above-described embodiment (particularly, the Embodiment 2) are assigned by the same names, and descriptions of the similar points to those of the above-described elements may be omitted. The description will be made mainly about the differences from the abovementioned elements.

[0446] FIG. 39 is a cross-sectional perspective view of a coupling member 528 according to Embodiment 5.

[0447] FIG. 40 is cross-sectional views of the coupling member 528 according to Embodiment 5 taken along a plane perpendicular to the rotation axis and including a position passing through the drive transmission portion 573.

[0448] FIG. 41 is a cross-sectional view of the coupling member 528 and the main assembly driving shaft 101 according to Embodiment 5 taken along a plane perpendicular to the rotation axis and including a position passing through the engagement portion 573.

[0449] FIG. 42 illustrates the structure of a mold used for forming the flange member 570 according to Embodiment 5.

[0450] FIG. 43 is a perspective view of an alignment member 533 according to Embodiment 5.

[0451] FIG. 44 is an illustration of the alignment member 533 according to Embodiment 5 as viewed in the Z direction from the outer side.

[0452] FIG. 45 is a sectional view of the coupling member 528 according to Embodiment 5.

[0453] FIG. 46 is a illustration of the flange member 570 according to Embodiment 5 as viewed in the Z direction from the outer side.

[0454] FIG. 47 in an illustration of the assembly of the coupling member 528 according to Embodiment 5.

[0455] FIG. 48 is an illustration of the aligning member 533 according to Embodiment 5 as viewed from the inside in the Z direction.

[0456] FIG. 49 is sectional views illustrating a operation of mounting the coupling member 528 to the main driving shaft 101 according to Embodiment 5.

[0457] FIG. 50 is sectional views illustrating the operation of mounting the coupling member 528 to the main assembly driving shaft 101 according to Embodiment 5.

[0458] FIG. 51 is a sectional view illustrating drive transmission from the main assembly driving shaft 101 to the coupling member 528 according to Embodiment 5.

[0459] FIG. 52 is a illustration of the flange member 570 according to Embodiment 5 as viewed in the Z direction from the inner side.

[0460] FIG. 53 is a sectional view illustrating drive transmission from the main assembly driving shaft 101 to the coupling member 528 according to Embodiment 5.

[0461] FIG. 54 is a cross-sectional view in which the position of the main assembly driving shaft 101 and the coupling member 528 deviates from the tolerance of parts in Embodiment 5.

[0462] FIG. 55 is cross-sectional views illustrating a dismounting operation of the coupling member 528 from the main assembly driving shaft 101 according to Embodiment 5.

[0463] FIG. 56 is sectional views illustrating drive transmission in which a winding portion 574b of the base portion 574 of the coupling member 528 according to Embodiment 5 is larger in diameter than the shaft portion 101f of the main assembly driving shaft 101.

[0464] FIG. 57 is sectional views illustrating drive transmission in which the winding portion 574b of the base portion 574 of the coupling member 528 according to Embodiment 5 is smaller in diameter than the shaft portion 101f of the main assembly driving shaft 101.

[0465] As shown in FIG. 39, the coupling member 528 includes a flange member (driving force receiving member) 570, an aligning member (positioning member) 533 having an inverted conical shape 533a, although the details will be described hereinafter. The base portion 574 is arranged so as to overlap the driving force receiving surface (driving force receiving portion) 573a in the Z direction. That is, when the base portion 574 and the driving force receiving surface 573a are projected onto the axis line of the drum unit, at least parts of respective projection areas overlap.

[0466] Further, the driving force receiving surface (driving force receiving portion) 573a and the base portion 574a of the base portion 574 are provided on the inner peripheral surface 571b of the cylindrical portion 571. That is, in the Z direction, the root portion 574a is outside the photosensitive drum 1.

[0467] Also, as shown in FIG. 45, the root portion 574a of the base portion 574 is arranged so as to overlap the entire area of the driving force receiving surface 573a in the Z direction.

[0468] The root portion 574a is the rear end (the radially outer end portion) of the base portion 574, and the base portion 574 is a connecting portion connected to the flange member 570 (the inner peripheral surface 571b). The base portion 574a is the supported portion of the base portion 574. The base 574 is supported by the flange member 570 on the base portion 574a.

(Description on Flange Member)

[0469] As shown in FIG. 46, a plurality of engaging portions 573 and a plurality of base portions 574 are symmetrically arranged on the flange member 570. That is, the engaging portions 573 are arranged at three positions (120 degrees spacing, substantially equal intervals) at regular intervals in the circumferential direction of the flange member 570. Similarly, the base portions 574 are also arranged at three positions at regular intervals in the circumferential direction of the flange member 570.

[0470] The engaging portion 573 is a projecting portion (a projecting portion, a protruding portion) projecting toward the inside at least in the radial direction of the coupling member 528 (the radial direction of the drum unit). The engaging portion 573 is disposed at the free end of the base portion 574 and is supported by the base portion 574.

[0471] The base portion 574 is an extending portion (extending portion, extension portion) extending in the circumferential direction of the coupling member 528. The direction in which the base portion 574 extends intersects the projecting direction of the engaging portion 573. In more detail, the base portion 574 extends at least in the circumferential direction of the coupling member 528 (the flange member 570). In other words, the base 574 extends at least in the direction of rotation of the drum unit.

[0472] The base portion 574 and the engaging portion 573 are support portions for movably supporting the driving force receiving portion 573a. The base portion 574 has a deforming portion (deforming portion, flexible portion) elastically deformed to move the driving force receiving portion 573a. The base 574 is configured to deform with the fixed end thereof as a fulcrum.

[0473] The engaging portion 573 is configured to engage with the main assembly driving shaft 101. The engaging portion 573 is provided with a driving force receiving surface (driving force receiving portion) 573a capable of receiving a driving force (rotational force) for rotating the photosensitive drum 1.

[0474] The projecting amount of the engaging portion 573 (the distance projecting from a surface of the base portion 574) measured along the radial direction is 1.2 mm. In order to engage with the driving transmission groove of the main assembly driving shaft 101, the projecting amount of the engaging portion 573 is desirably 0.6 mm or more as measured along the radial direction, more preferably 1.0 mm or more. Further preferably, the amount of projection measured along the radial direction is preferably 1.2 mm or more as in this embodiment.

[0475] With the structure in which the entire projecting portion of the engagement portion 573 is engaged with the main drive transmission groove, it is necessary for the base portion drive force receiving portion 573a to retreat beyond the projected amount of the engagement portion 573. Therefore, in this embodiment, the driving force receiving portion 573a can move at least 1.2 mm in the radial direction.

[0476] Further, a preferable movement amount of the driving force receiving portion 573a corresponds to a preferable projection amount of the engagement portion 573. That is, the movement amount of the driving force receiving portion 573a is desirably 0.6 mm or more as measured along the radial direction, more preferably 1.0 mm or more, further preferably 1.2 mm or more.

[0477] The engaging portion 573 and the base portion 574 are support portions that movably support the driving force receiving surface 573a. The base portion 574 is an elastically deformable portion (elastically deforming portion, flexible portion), and the base portion 574 deforms so that the driving force receiving surface 573a moves.

[0478] The driving force receiving surface 573a is the outside part of the drum unit (outside part of the process cartridge), that is, the drive transmitting portion (driving force transmitting portion) where the driving force (rotational force) is transmitted from the device main assembly.

[0479] The base portion 574 extends in a direction different from the projecting direction of the engaging portion 573 (a direction crossing the protruding direction). That is, the base portion 574 at least extends in the circumferential direction (rotational direction) of the flange member 570. More specifically, the base portion 574 extends from the flange member 570 toward the downstream side in the rotational direction. The free end of the base portion 574 is an end portion in the downstream side with respect to the rotational direction. The rear end (root portion 574a) of the base portion 574 is the upstream end portion with respect to the rotational direction. Also, the free end of the base portion 574 is disposed radially inward of the rear end. That is, the free end of the base portion 574 is a end portion on the inner side with respect to the radial direction, and the rear end (base portion 574a) of the base portion is an outside end portion with respect to the radial direction.

[0480] An engaging portion 573 is provided on the downstream side (free end side) of the base portion 574. An end portion (rear end) in the upstream side of the base portion 574 is a connecting portion that is connected with the flange member 570. The rear end of the base portion 574 is a supported portion that is supported by the flange member 570 and is a root portion 574a of the base portion 574.

[0481] The extending direction of the base portion 574 is substantially perpendicular to the rotation axis of the flange member 570 (drum unit). That is, the straight line connecting the front end and the rear end of the base portion 754 and the axis form a angle which is substantially 90 degrees. In other words, both the front end and the rear end of the base portion 574 are positioned on the same section plane parallel to the rotation axis of the flange member 570.

[0482] As shown in FIG. 50, on the same cross section perpendicular to the axis of the flange member 570, the portion from the free end to the rear and of each of the three bases 574 is arranged. All three engaging portions 573 and three root portions 574a are arranged on the same cross section. In other words, the plurality of engaging portions 573 and the plurality of base portions 574 are substantially at the same position with respect to the Z direction.

[0483] As shown in part (a) of FIG. 40, the base portion 574 has a root portion 574a, a winding portion 574b, and a straight portion 574c linearly connecting the root portion 574a and the winding portion 574b. A root portion 574a is a portion (connecting portion) where the inner diameter portion (inner surface, inner peripheral portion) of the flange member 570 and the base portion 574 are connected. The straight portion 574c is a substantially straight shape (substantially flat plate shape) portion. The winding portion 574b is a portion that is to be wound around the main assembly driving shaft 101. That is, when the flange member 570 receives the driving force (rotational force) from the main assembly driving shaft 101 through the engaging portion 573, the winding portion 574b winds around the main assembly driving shaft 101 and contacts the main assembly driving shaft 101. The winding portion 574b has a curved surface (bow-shaped surface). The winding portion 574b is curved so as to follow the main assembly driving shaft 101. In other words, the winding portion 574b is curved along the circumferential direction (rotational direction) of the coupling member 528. In other words, the winding portion 574b has a curved surface that faces radially inward (on the axis line side of the coupling member), and is a curved surface recessed radially outward.

[0484] Further, the winding portion 574b is disposed on the side where the driving force receiving surface 573a is provided. The driving force receiving surface 573a and the winding portion 574b form an acute angle.

[0485] As described above, an engaging portion 573 is provided at the free end of the base portion 574. That is, the base portion 574 is a portion that supports the engaging portion 573. Similarly to the above-described embodiments, the base portion 574 is deformed, so that the engaging portion 573 can be moved in the radial direction of the flange member 570.

[0486] The resin material forming the base portion 574 and the engaging portion 573 is formed integrally with the resin forming the flange member 570. However, the present invention is not limited to such a structure. The engaging portion 573 may be made of a member different from that of the base portion 574 and may be adhered to the free end of the base portion 574, for example. Similarly, the base portion 574 may be formed of a material different from the other portions of the flange member 570, or the base portion 574 may be dismountable from the flange member 570.

[0487] In order to increase the strength of the base portion 574, a metal may be provided inside the resin material forming the base portion 574. In FIG. 50 and so on, a plate-shaped metal is provided inside the resin. Such a structure will be described hereinafter with respect to another embodiment (FIG. 65 and so on).

[0488] The width of the base portion 574 measured along the Z direction is equal to or greater than the width of the driving force receiving surface 573a measured along the Z direction.

[0489] Although the effect will be described later, the length of a perpendicular line drawn from the rotation center (rotation axis) of the flange member 570 to the surface of the winding portion 574b is substantially the same as or larger than the radius of the shaft portion 101f of the main assembly driving shaft 101. In other words, when the flange member 570 is projected on the plane perpendicular to the rotation axis of the flange member 570, the radius R1 of the arc forming the inner diameter of the winding portion 574b on the plane (projection plane) is substantially the same or larger than the radius R2 of the shaft portion 101f.

[0490] As shown in part (a) of FIG. 40, the straight portion 574c has a shape extending in a tangential direction of the inner diameter of the winding portion 574b. In other words, the straight portion 574c is in the form of a flat plate integral with the arc end of the winding portion 574b, and is connected to the inner diameter portion of the flange member 570 at the root portion 574a. The tangent line at the end of the winding portion 574b is substantially parallel to the straight portion 574c.

[0491] Here, as shown in part (c) of FIG. 40, in the radial direction of the flange member 570, a distance from the inner diameter end 573b of the driving force receiving surface 573a to the inside diameter of the winding portion 574b is H1.

[0492] In the radial direction of the flange member 570, a distance from the outer shape of the engaging portion 573 to the inner diameter of the cylindrical portion 571 is H2. In this case, the engaging portion 573 and the base portion 574 are configured to satisfy a relationship of H1≤H2. By adopting such a structure (shape), the following effects can be obtained.

[0493] Even when the engaging portion 573 moves the inner diameter end 573b of the driving force receiving surface 573a outward in the radial direction H1, interference between the driving force receiving surface 573 and the inner peripheral surface 571b of the cylindrical portion 571 can be suppressed. In the course of mounting the coupling member 528 to the main assembly driving shaft, when the engagement portion 573 is brought into contact with the main driving shaft 101, the engagement portion 573 can reliably be retracted assuredly outward in the radial direction.

[0494] As described above, the length of the perpendicular line drawn from the rotation center of the flange member 570 to the surface of the winding portion 574b is substantially the same as the radius of the shaft portion 101f of the main assembly driving shaft 101. Therefore, the inner diameter end 573b of the driving force receiving surface 573a can move to radially outside of the shaft portion 101f without an interference between the outer shape of the engaging portion 573 and the mounting portion 572.

[0495] As shown in FIG. 41, a thickness measured in the radial direction of the winding portion 574b in the side of the driving force receiving surface 573a is defined as a free end side thickness (the thickness on the driving force receiving surface side) 574k, and a thickness of the straight portion 574c is defined as a straight portion thickness 574l (rear side thickness). The following effect can be provided by forming the shape of each part so that a relationship of free end side thickness 574k≥straight portion thickness 574l is satisfied.

[0496] As shown in FIG. 41, when the driving force receiving surface 573a receives the rotational force F1 from the main assembly driving force transmitting surface 101b, the engaging portion 573 receives a moment M to tend to deform radially outward with the connecting portion between the engaging portion 573 and the base portion 574 as a fulcrum. The deformation of the engaging portion 573 by this moment M can be reduced by increasing the free end side thickness 574k supporting the outer end 573c functioning as the fulcrum of the deformation against the deformation. On the other hand, if the thickness 574l is increased over the range up to the straight portion, the load required when mounting the coupling member 528 to the main assembly driving shaft 101 increases. In other words, the load required to retract the base portion 574 toward the outside in the radial direction becomes large, and therefore, it becomes difficult for the user to mount the cartridge.

[0497] Therefore, by selecting the relationship of the front end side thickness 574k≥the straight part thickness 574l, it is possible to accomplish both the reduction in deformation of the engagement part 573 and the easy cartridge mountability, preferably.

[0498] Further, in FIG. 41, the engaging portion 573 is a retractable outwardly in the radial direction of the coupling member 528 (radial direction of the photosensitive drum unit 30). The driving force receiving surface 573a provided in the engaging portion 573 is inclined with respect to the moving direction of the engaging portion 573. In the cross-sectional view of FIG. 41, a straight line B3 is a line extending along the direction in which the engaging portion 573 moves in the retraction. The straight line B4 is a line along the driving force receiving surface 573a. It is understood that the straight line B3 and the straight line B4 crosses with each other. By this, the driving force receiving surface 573a bites into the driving transmission groove 101a in a state that the driving force receiving surface 573a is in contact with the driving transmission groove 101a, so that the engaging portion 573 does not easily retreat from the driving transmission groove 101a. That is, the engagement between the engagement portion 573 and the drive transmission groove 101a is stabilized.

[0499] Particularly, the driving force receiving surface 573a is inclined relative to the moving direction of the engaging portion 573 (line B3) such that the inner diameter side (free end side) is upstream of the outer diameter side (root side) with respect to the rotational direction of the coupling member 528. Therefore, when the coupling member 528 (photosensitive drum unit 30) rotates, the force received from the driving force receiving surface 573 is in a direction to engage the engaging portion 573 with the main assembly driving transmission groove 101a. The state of engagement between the engagement portion 573 and the main assembly drive transmission groove 101a is stabilized, so that the disengagement of the engagement portion 573 and the main assembly drive transmission groove 101a is suppressed.

[0500] Part (a) of FIG. 40 in an illustration of the flange member 570 as viewed in the Z direction. As shown in part (a) of FIG. 40, as viewed along the Z direction, the root portion 574a is disposed upstream of the flange member 570 (in the rotational direction) with respect to a straight line drawn from the inner diameter end 573b of the driving force receiving surface 573a in a direction perpendicular to the driving force receiving surface.

[0501] Further, as viewed along the Z direction, such a ridge line on the side of the driving force receiving surface 573a among ridge lines formed by the straight portion 574c and the inner peripheral surface 571b of the cylindrical portion 571 as is in the driving force receiving surface 573a is called an inner ridge line 574d, and the ridge line in the opposite side of the driving force receiving surface 573a is called a outer ridge line 574e. As shown in part (b) of FIG. 40, the inner ridge line 574d is connected to the inner peripheral surface 571b of the cylindrical portion 571 with a arc larger than the outer ridge line 574e.

[0502] This is because it is preferable that the connecting surface where the base portion 574 and the inner peripheral surface 571b of the cylindrical portion 571 are connected to each other is as large as possible. This is because, when the driving force receiving surface 573a receives the driving force, the force applied to the inner peripheral surface 571b of the cylindrical portion 571 to which the root portion 574a is connected can be dispersed, and therefore, the deformation of the cylindrical portion 571 can be suppressed. As a result, even if the load received by the photosensitive drum unit 30 changes, the deformation amount of the cylindrical portion 571 is small, so that the influence of deformation on the rotation of the photosensitive drum unit 30 can be suppressed to a small degree. It is desirable to make the connecting surface between the base portion 574 and the cylindrical portion 571 as large as possible.

[0503] As shown in part (b) of FIG. 40, as viewed in the Z direction, an angle I formed in the outer ridge line 574e side between the angle among angles between the straight portion 574a and a line passing through the root portion 574a among the tangent lines at the inner diameter of the mounting portion 572 is acute.

[0504] The fulcrum point 574f of the elastic deformation of the base portion 574 is in the neighborhood of the portion where the influence of the arc of the ridge line formed by the straight portion 574c and the cylindrical portion 571 disappears. That is, when the inner ridge line 574d and the outer ridge line 574e are arcs of the same size, the angle I is acute. Therefore, it is near the intersection of the center line of the straight portion 574c and a straight line drawn from the end of the ridge line on the inner diameter side of the outer ridge line 574e perpendicularly to the center line of the straight portion 574c.

[0505] If the ridge line on the side of the outer ridge line 574e is gentle, the position of the fulcrum point 574f of elastic deformation is shifted to the point 574f at the time when the arc is enlarged, because the angle I is an acute angle on the side of the outer ridge 574e. Then, the elastically deformable length of the base portion 574 is shortened, and the mountability of the coupling member 528 to the main assembly driving shaft 101 is deteriorated.

[0506] An intersection point between a straight line perpendicular to the straight portion 574c from the fulcrum point 574f and the inside of the straight portion 574c is called an intersection point 574m. Even if the arc of the inner ridge line 574d is made large enough to pass through the intersection 574m, the range in which the influences of the arc of the ridge line formed by the straight portion 574c and the mounting portion 572 extend remains unchanged. That is, even if the arc of the ridge line of the inner ridge line 574d is increased not more than to the extent that a arc passing through the intersection point 574m, the large connecting surfaces at which the base portion 574 574 and the cylindrical portion 571 are connected with each other can be assured without deteriorating the mountability of the coupling member 528 to the main assembly driving shaft 101.

(Explanation on Manufacturing Method)

[0507] Referring to FIG. 42, the structure of a mold used for forming the flange member 570 will be described.

[0508] FIG. 42 is a sectional view illustrating a state in which the flange member 570 is molded in the metal mold.

[0509] The flange member 570 has a shape with which the flange portion 575 protrudes outward in the radial direction. In the case of molding such a shape, it is preferable to use a metal mold as shown in FIG. 42.

[0510] Specifically, as shown in the Figure, the metal mold has a two-piece structure including a left mold (cylindrical mold 560) and a right mold (mounting part mold 561). By aligning the right and left molds, a space portion (mold cavity, hollow portion) having the same shape as the molded product is formed. The flange member 570 is formed by pouring the material into the space portion and solidifying it in the mold. The mold has a structure in which a mold parting plane 562 (a plane along which the mold is divided, a plane at which the mold halves are contacted), which is a portion for fitting the right and left molds, is disposed in the neighborhood of the space forming the flange portion 575. The cylindrical mold 560 has a shape including a space for molding the outer periphery of the cylindrical portion 571. Similarly, the mounting portion side mold 561 has a shape having a space for molding the mounting portion 572.

[0511] In the case that the coupling member 570 is molded using such a metal mold, it is preferable to use a thermoplastic resin from the standpoint of mass productivity. More particularly, materials such as POM and PPS are considered to be preferable. However, in order to satisfy the requirement of strength and so on, other materials may be appropriately selected. Specifically, a thermosetting resin or a metallic material may be used.

[0512] Similarly to Embodiment 1, the engaging portion 573 has a mounting taper 573d at one end in the Z direction and a dismounting taper 573e at the other end. Therefore, it is difficult to dispose the mold parting plane 562 of the mold on either end surface of the engaging part 573 with respect to the Z direction.

[0513] This is because it is difficult to take the molded flange member 570 out of the mold if the mold parting plane 562 of the mold is on the end surface of the engagement portion 573 when using a two-part mold. That is, either of the two molds can not move relative to the flange member 570.

[0514] Similarly, the driving force receiving surface 573a has a shape in which the outer side (downstream side in the Z1 direction) of the photosensitive drum unit 30 is twisted toward the upstream side in the rotational direction relative to the inner side (downstream side in the Z2 direction). Therefore, the shape forming the driving force receiving surface 573a is provided on the mounting portion side mold 561 side. This is because if the driving force receiving surface 573a is formed by the left side (the cylindrical side mold 560), the cylindrical side metal mold 560 can not be removed from the driving force receiving surface 573a.

[0515] It is easier to produce the molds if the mold parting plane 562 is made as straight as possible, since then the mold parting plane 562 can be produced with high accuracy. Therefore, if the mold parting plane 562 is formed as straight as possible, the possibility of occurrence of resin leakage or the like can be reduced.

[0516] In order to straighten the mold parting line 562 of the engaging portion 573, it is necessary to arrange the driving force receiving surface 573a at the back side of the photosensitive drum unit 30 beyond at least the insertion taper 573d. Therefore, in this embodiment, the end of the insertion taper 573d and the end of the driving force receiving surface 573a are arranged at the same position in the Z direction.

[0517] In this embodiment, the inner diameter of the portion where the root portion 574a of the flange member 570 is disposed is substantially the same as the inner diameter of the other portion. Specifically, the inner diameter of the portion where the root portion 574a is disposed is substantially the same as the inner diameter of the inner peripheral surface 571b of the cylindrical portion. Further, the inner diameter of the inner peripheral surface of the mounting portion 572 and the inner diameter of the portion where the root portion 574a is disposed are made substantially the same.

[0518] Further, as the flange member 570 is viewed along the Z direction, if another shape (protrusion or the like) is provided on the portion overlapping the base portion 574, the other shape and the base portion 574 are connected to each other when the flange member 570 is molded using the metal mold. When said another shape is connected to the base portion 574, the elastic deformation of the base portion 574 is obstructed.

[0519] Therefore, in the flange member of this embodiment, the flange member 570 does not have a portion overlapping (overlapping) the base portion 574 on a projection plane provided by projecting the flange member 570 on a plane perpendicular to the rotation axis (Z direction). Likewise, there is no overlap with the driving force receiving portion 573.

(Description on Alignment Member)

[0520] Referring to FIGS. 43 to 44, the structure of the alignment member (positioning member) 533 will be described.

[0521] In Embodiment 1, the alignment between the main assembly driving shaft 101 and the coupling member 28 is effected by the radial direction positioning portion 76a and the positioning in the Z direction is effected by the abutment portion 76b (as shown in FIGS. 14 and 15). The radial direction positioning portion 76a is disposed at a position overlapping with the engaging portion 73 in the Z direction. That is, when the radial direction positioning portion 76a and the engaging portion 573 are projected on the rotation axis of the coupling member 28, they are disposed so that at least part of the projected regions of them are overlapped with each other on the rotation axis.

[0522] On the other hand, in this embodiment, the base portion 574 is arranged so as to overlap the driving force receiving surface 573a in the Z direction. That is, the base portion 574 and the engaging portion 573 are disposed so that they overlap when projected on the rotation axis of the coupling member 528. When the base portion 574 and the engaging portion 573 are thus arranged, it is difficult to dispose the radial positioning portion as in Embodiment 1 so as to overlap the engaging portion 573 in the Z-axis direction.

[0523] Therefore, in this embodiment, the alignment member (positioning member) 533 having the inverted conical shape 533a described above is employed instead of the structure such as that of the radial direction positioning portion 76a disclosed in Embodiment 1. The coupling member 528 is positioned with respect to the main assembly driving shaft 101 by using the alignment member 533. The inverted conical shape 533a is provided by a substantially conical recess. The detailed shape of the alignment member 533 will be described below.

[0524] As shown in FIGS. 43 and 44, the aligning member 533 includes a inverted conical shape portion 533a, a fitting portion 533b, a retaining portion 533c, and a projection 533d for matching a phases of the flange member 570. The fitting portion 533b is fitted into the flange member 570. A retaining portion 533c has a function of suppressing the alignment member 533 from disengaging from the flange member 570.

[0525] As shown in FIG. 45, the inverted conical shape portion 533a is disposed on the inner side (the Z2 direction side) of the photosensitive drum unit 30 beyond the engagement portion 573. As the flange member 570 and the aligning member 533 are viewed along the Z direction, the flange member 570 and the aligning member 533 are assembled than that of each other so that the center of the inverted conical shape 533a and the center of the photosensitive drum 1 aligned.

[0526] The inverted conical shape 533a has an abutment portion 533e abutting to the semispherical semispherical shape 101c at the free end of the main assembly driving shaft 101 when the photosensitive drum 1 is rotated. As shown in FIG. 45, the aligning member 533 is mounted to the flange member 570 such that in the state that the abutment portion 533e and the semispherical shape portion 101c contact to each other in the Z direction, the center 101h of the semispherical shape portion 101c of the main assembly driving shaft 101 is within the range of the driving force receiving surface 573a.

[0527] As shown in FIG. 45, the fitting portion 533b is disposed on the inner side (the Z2 direction side) of the photosensitive drum unit 30 with respect to the abutment portion 533e.

[0528] Further, the flange member 570 has a fitted portion 572a at a position corresponding to the fitting portion 533b. As described above, the center of the inverted conical shape 533a and the center of the photosensitive drum 1 can be aligned with high accuracy.

[0529] As shown in FIG. 43, the retaining portion 533c has a snap fit fashion and has a shape for suppressing disengagement of the aligning member 533 from the flange member 570. That is, the retaining portion 533c is a connecting portion that connects the aligning member 533 to the flange member 570.

[0530] As shown in FIG. 45, when the aligning member 533 is mounted to the flange member 570, the retaining portion 533c is located on the inner side (the Z2 direction side) of the photosensitive drum unit 30 with respect to the engaging portion 573 (the driving force receiving portion 573a). Therefore, even if the base portion 574 of the flange member 570 is deformed radially outward, the retaining portion 533c is configured so as not to prevent deformation (movement) in the radial direction of the base portion 574. That is, the engaging portion 573 does not contact with the retaining portion 533c when moving in the radial direction.

[0531] Also, as shown in FIGS. 45 and 46, the flange member 570 has a hooking portion 572b corresponding to the retaining portion 533c. As shown in FIG. 46, the hooking portion 572b is disposed in a position so as not to overlap with the base portion 574 as viewed along the Z direction.

[0532] The hooked portion 572b is disposed substantially in the middle of the two root portions 574 arranged so as to be adjacent to each other in the circumferential direction. Then, a gap between the base portion 574 and the hooking portion 572b can be assured in the circumferential direction. In this embodiment, three hook portions 572b engaged with the retaining portion 533c are disposed in the middle of the root portion 574a.

[0533] As shown in FIGS. 43 and 47, the convex portion 533d functioning as an assembling guide has a shape protruding radially outward from the fitting portion 533b. Therefore, when the alignment member 533 is mounted to the flange member 570, the phases of the retaining portion 533c and the hooking portion 572b can easily be matched. The recessed portion 533d is a phase determining portion for determining the phase of the aligning member 533 relative to the flange member 570 (the attitude in the rotational direction, the position in the rotational direction).

[0534] As shown in FIG. 47, the cut-away portion 572c is disposed at a position spaced 90 degrees away from the clamp groove 572e in the circumferential direction. As in Embodiment 1, two clamp grooves 572e are equidistantly arranged around the rotation axis of the coupling member 528. That is, in other words, the cut-away portion 572c is disposed at the farthest position between the two clamp grooves 572e arranged at a position separated by 180 degrees in the circumferential direction of the flange member 570. By this, it is possible to suppress the influence of the clamp groove e and the cut-away portion 572c on the rigidity of the flange member 570.

[0535] Furthermore, as shown in FIG. 48, the aligning member 533 has an outer cylindrical rib 533f forming the fitting portion 533b and an inner cylindrical rib 533g on the back side of the outer end of the inverted conical shape 533a. In addition, the alignment member 533 includes a plurality of radial ribs 533i so as to connect the outer cylindrical rib 533f and the inner cylindrical rib 533g. The ribs are not provided inside the inner cylindrical rib 533g.

[0536] By connecting the outer cylindrical rib 533f and the inner cylindrical rib 533g with the radial ribs 533i, it is possible to suppress the deformation of the aligning member 533 when the aligning member 533 is press-fitted into the flange member 570. Further, by disposing the rib inside the inner cylindrical portion 533g, it is possible to suppress increase of the thickness of the central portion of the conical shape 533a. By this, dimensional accuracy of the inverted cone shape 533a which affects the alignment function can be improved.

[Engaging Process of Coupling Member with Main Assembly Drive Shaft]

[0537] A process of engagement of the coupling member 528 with the main assembly driving shaft 101 will be described in detail.

[0538] FIG. 49 is a longitudinal sectional view illustrating the operation of mounting the coupling member to the main assembly driving shaft. Part (a) of FIG. 49 is an illustration of a state in which the coupling member 28 has started engaging with the main driving shaft 101. Part (e) of FIG. 49 shows a state in which the cartridge 7 has been mounted to the image forming apparatus main assembly 100A, the cartridge door 104 has been closed, the lower front side cartridge guide 109 has been raised, and the cartridge 7 has been positioned relative to the image forming apparatus main assembly 100A. Part (b) of FIG. 49 to part (d) of FIG. 49 are illustrations of a process of connecting the coupling member 528 to the main assembly driving shaft 101 between part (a) of FIG. 49 and part (e) of FIG. 49. As in Embodiment 1, the main assembly driving shaft 101 hangs downward in the direction of gravity by a small angle due to its own weight.

[0539] Further, FIG. 50 in a illustration of a state in which the phase of the main assembly drive transmission groove 101a and the phase of the engagement portion 573 (driving force receiving surface 573a) are not aligned with each other. In other words, in FIG. 50, the engaging portion 573 (the driving force receiving surface 573a) does not enter the main assembly drive transmission groove 101a and FIG. 50 shows a state in which they are not engaged with each other.

[0540] Similarly to Embodiment 1, as shown in part (a) of FIG. 49, when the cartridge 7 is positioned relatively to the image forming apparatus main assembly 100A (as shown in part (e) of FIG. 49), the coupling member 528 is inserted into the main assembly driving shaft 101 in a state inclined by about 0.5 to 2 degrees.

[0541] First, as shown in part (b) of FIG. 49, the free end of the inner peripheral surface 571b of the cylindrical portion 571 of the flange member 570 abuts against the rough guide portion 101g of the main assembly driving shaft 101. As shown in the Figure, the main assembly driving shaft 101 is configured to be supported by the bearing portion 101d in the cantilever fashion. Therefore, the coupling 7 is inserted into the main assembly driving shaft 101 in a state in which the rough guide portion 101g of the main assembly driving shaft 101 fits the inner peripheral surface 571b of the coupling member 570. Similarly to Embodiment 1, in the Z direction, the driving force receiving surface 573 of the engaging portion 573 has a length L2 which satisfy L1>L2, where L1 is a distance from the front end surface of the cylindrical portion 571 to the front end surface of the engaging portion 573 (as shown in FIG. 45). Therefore, before the semispherical shape 101c at the free end of the main assembly driving shaft 101 hits the engaging portion 573, the rough guide portion 101g of the main assembly driving shaft 101 follows the inner peripheral surface 571b of the coupling member 570.

[0542] By this, the main assembly driving shaft 101 is guided by the coupling member 528. Therefore, the semispherical shape portion 101c at the free end of the main assembly driving shaft 101 is prevented from hitting a unintended portion of the engaging portion 573 or the base portion 574 with the result of impact to the engaging portion 573 and/or the base portion 574. That is, the engaging portion 573 and the base portion 574 can be protected.

[0543] As shown in part (c) of FIG. 49, when the coupling member 528 is further inserted toward the back side of the main driving shaft 101, the insertion taper surface 573d of the engagement portion 573 and the main driving shaft 101 and the semispherical shape 101c abut to each other. Due to the inclined surface of the insertion tapered surface 573d and the spherical shape of the semispherical shape 101c, the main assembly driving shaft 101 is guided substantially to the center of the three engaging portions 573.

[0544] When the coupling member 528 is further inserted into the main assembly driving shaft 101, the base portion 574 elastically deforms radially outward so that the engagement portion 573 follows the semispherical shape 101c. As a result, as shown in FIG. 50, the engaging portion 573 moves (retracts) to the outer diameter surface of the shaft portion 101f of the main assembly driving shaft 101. By this movement, as shown in part (d) of FIG. 49, the coupling member 528 is mounted to the main assembly driving shaft 101 until the dismounting tapered surface 573e of the engagement portion 573 comes deeper in the Z direction than the main assembly side dismounting taper 101i of the main assembly driving shaft 101.

[0545] Thereafter, similarly to Embodiment 1, the cartridge 7 is lifted so that the drum unit bearing member 39L of the cartridge 7 abuts against the front side cartridge positioning portion 110. By thus lifting the cartridge 7, the cartridge 7 is positioned relative to the image forming apparatus main assembly 100A (as shown in part (d) of FIG. 21). By this operation of the cartridge 7, as shown in part (e) of FIG. 49, the inclination of the coupling member 528 is eliminated. That is, the coupling member 528 and the drum unit are in an attitude capable of forming an image.

[0546] When the main assembly driving shaft 101 rotates, as shown in part (b) of FIG. 50, the main assembly drive transmission groove 101a and the engagement portion 573 come to have the same phase. As a result, the elastic deformation of the base portion 574 is eliminated, a part of the engagement portion 573 enters the main assembly drive transmission groove 101a, and the coupling member 528 and the main assembly driving shaft 101 are engaged with each other.

[0547] When the phases of the main assembly drive transmission groove 101a and the engagement portion 573 are in alignment with each other, at least part of the elastic deformation of the base portion 574 is eliminated at the stage of part (d) of FIG. 49, and the state of part (b) of FIG. 50 is provided. That is, the base portion 574 is deformed so as to move the engaging portion 573 inward in the radial direction when shifting from the state shown in part (a) of FIG. 50 to the state shown in part (b) of FIG. 50. Strictly speaking, the state of the base portion 574 which has been deformed outward in the radial direction is at least partially restored, by which the engaging portion 573 moves at least inward in the radial direction.

[0548] In this manner, the base portion 574 advances the engaging portion 573 into the main assembly drive transmission groove 101a, and causes the engaging portion 573 to engage with the main assembly driving transmission groove 101a of the main assembly driving shaft 101.

[Driving of Coupling Member by Main Assembly Drive Shaft]

[0549] Referring to FIGS. 51 to 57, transmission of rotational drive from the main driving shaft 101 to the coupling member 528 will be described.

[0550] As described above, after closing the cartridge door 104 of the image forming apparatus main assembly 100A to which the cartridge 7 is mounted, the main assembly driving shaft 101 rotates. As a result, the phase of the engagement portion 573 and the phase of the main assembly drive transmission groove 101a match each other, with the result of the state shown in part (b) of FIG. 50. The main assembly driving shaft 101 is configured to be rotatable in the rotational direction for image forming operation and also in the opposite direction.

[0551] As shown in part (b) of FIG. 50, when the main assembly driving shaft 101 further rotates in the counterclockwise direction, as shown in FIG. 51, the main assembly drive transmission surface 101b abuts against the driving force receiving surface 573a. As a result, the rotational driving force of the main assembly driving shaft 101 is transmitted to the photosensitive drum 1 by way of the coupling member 528.

[0552] As in Embodiment 1, the driving force receiving surface 573a is twisted about the center of the rotation axis of the flange member 570. The twisting direction is such that the outer side (the Z1 direction side) of the photosensitive drum unit 30 of the driving force receiving surface 573a is upstream, with respect to the rotational direction of the photosensitive drum 1, of the inner side (downstream side in the Z2 direction) 52 (as shown in FIG. 52).

[0553] It will suffice if the phases, in the rotational direction, of the two points in contact with the driving shaft are different, and the structure may be any if it provides the same function as the twisted surface. For example, it will suffice if the shape is such that outer side (downstream side in Z1 direction) of the driving force receiving surface 573a is in the upstream side of the inner side (downstream side in Z2 direction) with respect to the peripheral moving direction of the rotation of the photosensitive drum 1. In other words, a straight line connecting the cylinder inner end portion and the cylinder outer end portion along the cylinder axis direction of the engagement portion 573 crosses with the rotation axis of the cylinder.

[0554] By employing such a shape, when the driving force receiving surface 573a is driven, a force is produced in the direction of drawing the photosensitive drum unit 30 toward the bearing portion 101d side of the main assembly driving shaft 101.

[0555] Due to this force (force in the Z1 direction), the inverted conical shape 533a of the alignment member 533 is brought into a state of certainly abutting against the semispherical shape 101c at the free end of the main assembly driving shaft 101. When the inverted conical shape 533a contacts the semispherical shape 101c, the radial position of the coupling member with respect to the main assembly driving shaft 101 is determined. Furthermore, the position of the coupling member 528 in the longitudinal direction with respect to the main assembly driving shaft 101 is also determined. That is, the inverted conical shape 533a is a radial direction positioning portion (aligning portion) for determining the radial direction position of the coupling member 528 (drum unit) with respect to the main assembly driving shaft 101. In addition, the inverted conical shape 533a is also a longitudinal direction positioning portion (axial direction positioning portion) for determining the position of the coupling member 528 (drum unit) in the longitudinal direction relative to the main assembly driving shaft 101.

[0556] The radial positioning portion and the longitudinal positioning portion need not be conical recess such as a inverted conical shape recess 533a. The shape of the radial direction positioning portion and the longitudinal direction positioning portion is not limited if it can determine the position of the photosensitive drum unit 30 relative to the main assembly driving shaft 101 when it contacts to the free end (semispherical shape 101c) of the main assembly driving shaft 101. For example, it is preferable that they are recessed shrinking toward the bottom. As such a shape, a non-circular cone shape such as a pyramid (square pyramid or the like) may be used. However, if the recessed portion is a conical shape symmetrical with respect to the axis of the coupling member 528, as in the case of the inverted conical shape 533a of this embodiment, the position of the coupling member 528 can be maintain with particularly high accuracy.

[0557] Since the inverted conical shape 533a only needs to have a region for contacting with the main assembly driving shaft 101, the non-contacting region may have any shape. For example, the inverted conical shape 533a which is not in contact with the main assembly driving shaft 101 may be a recessed portion having an open bottom.

[0558] As the flange member 570 is viewed along the Z direction, the root portion 574a is disposed upstream of a straight line drawn from the inner diameter end 573b of the driving force receiving surface 573a in a direction perpendicular to the driving force receiving surface 573a, with respect to the direction of the rotation of the flange member 570 (part (a) of FIG. 40). By this, the following effects can be provided.

[0559] As shown in FIG. 51, the driving force F1 is divided into a component Fh in the direction parallel to the straight line connecting the inner diameter end 573b of the driving force receiving surface and the root portion 574a of the base portion 574, and a component Fv in the vertical direction. The component Fv in the vertical direction is a component of attracting the engaging portion 573 and the base portion 574 toward the shaft portion 101f side. That is, due to the component Fv, a moment for rotating the base portion 574 counterclockwise with the base portion 574a as a fulcrum is generated at the base portion 574. As a result, the engaging portion 573 and the base portion 574 are pulled into the shaft portion 101f.

[0560] In FIG. 51, when a normal line perpendicular to the driving force receiving surface 573a is extended from the free end of the driving force receiving surface 573a, the base portion 574 extends so as to cross with the normal line. That is, the fixed end of the base portion 574 is disposed on the upstream side, in the rotational direction of the coupling member, of the normal line. With such an arrangement relationship, a moment that causes the base portion 574 to wind around the shaft portion 101f of the main assembly driving shaft 101 is generated, which is preferable.

[0561] Since the main assembly driving shaft 101 is rotating, when the base portion 574 is pulled, the winding portion 574b winds around the shaft portion 101f. As a result, the contact area between the base portion 574 and the shaft portion 101f is larger than the contact area (shown in part (b) of FIG. 50) in which the base portion 574 is not wound.

[0562] As a result of winding the winding portion 574b around the shaft portion 101f, as shown in FIG. 53, the base portion 574 receives the rotational force Fc generated by the driving force F1 at the straight portion 574c. Since the rotational force Fc is a component in the direction perpendicular to the straight portion 574c, it is a component in the direction of strong rigidity of the straight portion 574c. As a result, the amount of deformation of the base portion 574 can be suppressed to be small. By doing so, even if the load on the photosensitive drum unit 30 changes, the amount of deformation of the base portion 574 is small, so that the influence of deformation on the rotation of the photosensitive drum unit 30 can be suppressed to a small degree.

[0563] By the structure in which the radius R1 of the arc forming the inner diameter of the winding portion 574b is substantially the same as or larger than the radius R2 of the shaft portion 101f, the following effects can be obtained.

[0564] As described above, when the driving force receiving surface 573a is driven by the main assembly driving transmission surface 101b, the base portion 574 is pulled into the shaft portion 101f of the main assembly driving shaft 101. As a result, the winding portion 574b winds around the shaft portion 101f. By the winding of the winding portion 574b, the rotational force of the main assembly driving shaft 101 is received by the straight portion 574c.

[0565] First, as shown in part (a) of FIG. 56, a case where the radius R1 of the winding portion 574b is larger than the radius R2 of the shaft portion 101f is considered. In this case, when the engaging portion 573 is in phase alignment with the main assembly driving transmission groove 101a and enters the main assembly driving transmission groove 101a, a gap is generated between the winding portion 573b and the shaft portion 101f.

[0566] Thereafter, when the driving force receiving surface 573a is brought into contact with the main assembly drive transmission surface 101b and receives the rotational force, as shown in part (b) of FIG. 56, a pulling force with the root portion 574a of the base portion 574 as a fulcrum point is provided, so that the winding portion 574b is wound around the shaft portion 101f. By this winding, the straight portion 74c can receive the rotational force substantially in the same manner as when the radius of the winding portion 574b is the same as the radius of the shaft portion 101f.

[0567] On the other hand, the case where the radius R1 of the winding portion 574b is smaller than the radius R2 of the shaft portion 101f will be described, referring to FIG. 57. As shown in part (a) of FIG. 57, when the engagement portion 573 is in phase alignment with the main assembly drive transmission groove 101a, the base portion 574 is deflected to a position where the straight portion 574c abuts against the shaft portion 101f at the contact point 574n. In such a case, there is a gap which becomes larger toward the engagement portion 573 side between the winding portion 574b and the shaft portion 101f. Thereafter, when the driving force receiving surface 573a abuts against the main assembly drive transmission surface 101b and receives a rotational force, the winding portion 574b is pulled with the contact point 574n as a fulcrum. However, the distance from the contact point 574n to the driving force receiving surface 573a is closer than the distance from the root portion 574a to the driving force receiving surface 573a. Therefore, the driving force F1 necessary for winding the winding portion 574b around the shaft portion 101f increases as compared with the case where the radius of the winding portion 574b is larger than the radius of the shaft portion 101f.

[0568] For this reason, the radius R1 of the winding portion 574b is preferably substantially the same as or larger than the radius R2 of the shaft portion 101f More preferable, since then the winding portion 574b can be wound around the shaft portion 101f with a smaller driving force F1.

[0569] As described above, the inverted conical shape 533a of the alignment member 533 is disposed so that the center 101h of the semispherical shape 101c comes within the range of the driving force receiving surface 573a of the flange member 570 in the Z direction (FIG. 45). When the engaging portion 573 and the center 101h are projected onto the axis line of the drum unit, the center 101h is inside the projection area of the engaging portion 573. In FIG. 45, the projected area of the engaging portion 573 is indicated by L2, and it is understood that the center 101h is disposed inside the area indicated by L2. By establishing such an arrangement relationship, the following effects can be provided.

[0570] The drum unit bearing member 39R and the drum unit bearing member 39L respectively abut against the rear side cartridge positioning portion 108 and the front side cartridge positioning portion 110. Therefore, the position of the cartridge 7 relative to the image forming apparatus main assembly 100A is determined. Here, the relative position between the main assembly driving shaft 101 and the coupling member 28 is affected by part tolerances. Specifically, the position is shifted due to the component part tolerances from the drum unit bearing member 39R to the coupling member 28 and the component part tolerances from the rear side cartridge positioning portion 108 to the main assembly driving shaft 101.

[0571] As shown in FIG. 54, the semispherical shape 101c abuts against the inverted conical shape 533a, so that the supporting both at the bearing portion 101d and the semispherical shape portion 101c support it established. That is, as viewed from the coupling member 528, the main assembly driving shaft 101 of the main assembly driving shaft 101 is tilted about the center 101h of the semispherical shape 101c. The same position as the center 101h in the Z-axis direction is a position that is least influenced by this tilting. The driving force receiving surface 573a is disposed at the same position as the center 101h in the Z axis direction, by which the influence of positional displacement can be minimized. That is, it is a position where the photosensitive drum 1 can be stably driven.

[Removal of Coupling Member from Main Driving Shaft]

[0572] Referring to FIG. 55, dismounting operation of the coupling member 528 from the main assembly driving shaft 101 will be described.

[0573] As shown in part (a) of FIG. 55, the drive force receiving surface 573a and the main assembly drive transmission surface 101b are in contact with each other when the rotational drive of the main assembly driving shaft 101 is stopped. In this state, a part of the engagement portion 573 is in the main assembly drive transmission groove 101a.

[0574] When the cartridge door 104 is opened, the lower front side cartridge guide 109 lowers, and the drum unit bearing member 39L separates from the side cartridge positioning portion 110 of the image forming apparatus main assembly 100A. At this time, as shown in part (b) of FIG. 55, the coupling member 528 and the main assembly driving shaft 101 are inclined by about 0.5 to 2 degrees with respect to the angle at the mounting complete state (Z direction).

[0575] When the cartridge 7 is started to be removed from the image forming apparatus main assembly 100A, as shown in part (c) of FIG. 55, the dismounting tapered surface 573e of the engaging portion 573 abuts to the main assembly side dismounting taper 101i. When the dismounting tapered surface 573e abuts to the main assembly side dismounting taper 101i, the base portion 574 begins to elastically deform and moves the engaging portion 573 outwardly in the radial direction along the main assembly side dismounting taper 101i.

[0576] Further, when the coupling member 528 is pulled out of the main assembly driving shaft 101, the state becomes the same as in part (a) of FIG. 50, in which the base portion 574 further elastically deforms, and the engagement portion 573 is inserted into the shaft portion 101f of the main assembly driving shaft 101. By moving the engaging portion 573 to the outer diameter surface of the shaft portion 101f, the coupling member 528 can be removed from the main assembly driving shaft 101 as shown in part (d) of FIG. 55.

[0577] Further, when the coupling member 528 is removed from the main assembly driving shaft 101, as shown in part (e) of FIG. 55, the elastic deformation of the base portion 574 is released and the position of the engagement portion 573 returns to the position before the elastic deformation.

[0578] By the above-described operation, the coupling member 528 can be removed from the main assembly driving shaft 101.

[0579] By using the coupling member 528 of this embodiment as described above, it is possible to reduce the deformations of the drive transmission portion 573 and the base portion 574 when receiving the driving force F1. As a result, even if the load received by the photosensitive drum unit 30 changes, it is possible to suppress the influence on the rotation of the photosensitive drum unit 30 to a small degree.

[0580] In this embodiment, the coupling member 528, the flange member 570, and the alignment member 533 are combined. However, depending on selection of material and molding method, there is no need to have two members, it may be unitized, or may be constituted by combining three or more members.

[0581] Referring to FIGS. 58 to 75, Embodiment 6 will be described.

[0582] In Embodiment 6, the driving force receiving portion 673a and its supporting portion (the base portion 674 and the engaging portion 673) are provided inside the photosensitive drum. In this embodiment, the support portion extends at least in the circumferential direction of the coupling member 628 as in Embodiment 5.

[0583] Elements corresponding to those of the above-described embodiment (particularly, the Embodiment 5) are assigned by the same names, and descriptions of the similar points to those of the above-described elements may be omitted. The description will be made mainly about the differences from the abovementioned elements.

[0584] FIG. 58 is a sectional view of the coupling member 628 according to Embodiment 5.

[0585] FIG. 59 is a cross-sectional view of the flange member 670 in Embodiment 6.

[0586] FIG. 60 is a view of the flange member 670 according to Embodiment 6 as viewed in the Z direction from the outer side.

[0587] FIG. 61 is a section of view illustrating an arrangement relationship in the Z direction of each part of the cleaning unit according to the Embodiment 6.

[0588] FIG. 62 is a sectional view illustrating a die structure of the flange member 670 according to the Embodiment 6.

[0589] FIG. 63 is a perspective view of an alignment member 633 according to Embodiment 5.

[0590] FIG. 64 is sectional views illustrating the mounting operation of the coupling member 628 to the main assembly driving shaft 101 according to Embodiment 6.

[0591] FIG. 65 is sectional views illustrating the mounting operation of the coupling member 628 to the main assembly driving shaft 101 according to Embodiment 6.

[0592] FIG. 66 is a view of the flange member 670 according to Embodiment 6 as viewed from the Z direction from the inner side.

[0593] FIG. 67 is a sectional view illustrating drive transmission from the main assembly drive shaft to the coupling member according to Embodiment 6.

[0594] FIG. 68 is sectional views illustrating the removal operation of the coupling member 628 from the main assembly drive shaft 101 according to Embodiment 6.

[0595] FIG. 69 is a sectional view illustrating a state in which the drive transmission from the main assembly driving shaft 101 to the coupling member 3628 is not stabilized, after long-term storage in a state that the phase of the engaging portion and the main assembly driving transmission groove are not aligned, in the case that the flange member is manufactured using a material exhibiting a large creep deformation.

[0596] FIG. 70 is a sectional view illustrating a metal mold structure for inserting the metal plate 635 into the flange member 670 according to the Embodiment 6.

[0597] FIG. 71 is a view of the flange member 670 according to Embodiment 6 as viewed in the Z direction from the outer side.

[0598] FIG. 72 is a cross-sectional view of the flange member 670 in Embodiment 6.

[0599] FIG. 73 is a sectional perspective view of the flange member 670 according to Embodiment 6.

[0600] FIG. 74 is a partial cross-sectional view of the flange member 670 according to Embodiment 6 cut by a straight portion cut-away portion 674g.

[0601] FIG. 75 is a partial sectional view of the flange member 670 according to Embodiment 6, taken along a winding portion cut-away portion 674h.

[0602] In Embodiment 5, the driving force receiving surface 573a and the base portion 574a of the base portion 574 are arranged on the inner peripheral surface 571b of the cylindrical portion 571 in the Z direction. In this embodiment, as shown in FIG. 59, the driving force receiving surface 673a and the root portion 674a are arranged in the Z direction in the mounting portion 672 (inside the photosensitive drum 1) in the Z direction in the inner circumference 672h. That is, the driving force receiving surface 673a and the root portion 674a are arranged on the back side (the Z2 direction side) of the end surface 675b of the flange portion 675 that abuts against the photosensitive drum 1 when the coupling member 628 is assembled to the photosensitive drum 1.

[Structure of Coupling Member]

[0603] As in Embodiment 5, the coupling member 628 is constituted by two members by combining the flange member 670 and the alignment member 633 (shown in FIG. 58). However, depending on selection of material and molding method, there is no need to have two members, it may be unitized, or may be constituted by combining three or more members.

[0604] Similarly to the previous embodiments, the coupling member 628 of this embodiment includes a driving force receiving surface (driving force receiving portion) 673a for receiving the driving force from the outside (main assembly driving shaft 101). The driving force receiving portion is provided on the projecting portion (the engaging portion 673), and the engaging portion 673 is supported by the base portion 674.

[0605] The engaging portion 673 and the base portion 674 are support portions for supporting the driving force receiving surface 673a. The base portion 674 is an extending portion (extension portion, extension portion) extending in the circumferential direction of the coupling member 628. An engaging portion 673 is provided at the free end of the base portion 674.

[0606] In this embodiment, as the supporting portion (the base portion 674 and the engaging portion 673) and the photosensitive drum 1 are projected onto the axis of the coupling member 628, the entire projection area of the supporting portion is in the projected area of the photosensitive drum 1. The description will be made.

(Description on Flange Member)

[0607] As in Embodiment 5, the engaging portions 673 are arranged at three positions (120 degrees interval, substantially equally spaced) at regular intervals in the circumferential direction of the flange member 670. Similarly, the base portions 674 are also arranged at three positions equally spaced in the circumferential direction of the flange member (as shown in FIG. 60).

[0608] Similarly to Embodiment 5, the base portion 674 includes a root portion 674a, a winding portion 674b, and a straight portion 674c linearly connecting the root portion 674a and the winding portion 674b.

[0609] As described above, the driving force receiving surface 673a and the root portion 674a are arranged in the back side (the Z2 direction side) of the end surface 675b of the flange portion 675 that abuts to the photosensitive drum 1 when the coupling member 628 is assembled to the photosensitive drum 1 (as shown in FIG. 59). However, a part of the engaging portion 673 including the insertion tapered surface 673d may protrude forward (Z1 direction) from the end surface 675b of the flange portion 75 to which the photosensitive drum 1 abuts.

[0610] Referring to FIG. 61, the arrangement of the other components of the cleaning unit 613 and the driving force receiving surface 673a will be described. FIG. 61 is a section of view illustrating an arrangement relationship, in the Z direction, of each part of the cleaning unit 613. As described above, an opening 614b of a cleaning frame 614 suppresses leakage of toner in the rotational direction of the photosensitive drum 1 by A blade-shaped rubber 66a of a cleaning blade 66 and a blow-off prevention sheet 626. In addition, the opening 614b is provided with end seal members 627 at respective end portions in the Z direction, and a part of the opening 614b is brought into contact with the blade-like rubber (elastic member) 66a in the Z direction to be in close contact with the photosensitive drum 1 to suppress toner leakage. In the Z direction, the driving force receiving surface 673a is disposed in front of the blade-like rubber 66a of the cleaning blade 66 (in the Z1 direction), and at least a part of the driving force receiving surface 673a overlaps at least with the end sealing member 627. In other words, when the driving force receiving surface 673a and the end seal member 627 are projected onto the axis of the drum unit, at least a part of the projection region of the driving force receiving surface 673a and at least a part of the projection region of the end seal member 627 overlap with each other.

[0611] As in Embodiment 5, the driving force receiving surface 673a is twisted above the center of the rotating shaft of the flange member 670. The twisting direction is such that the outside of the driving force receiving surface 673a (with respect to the Z1 direction) is upstream of the inside (with respect to the Z2 direction) of the driving force receiving surface 673a with respect to the rotational direction of the photosensitive drum 1, and the amount of twisting is set to approximately 1 degrees per 1 mm.

[0612] As in Embodiment 5, the length L2 of the driving force receiving surface 73 and the distance L1 from the front end surface of the cylindrical portion 71 to the front side end surface of the engaging portion 673 in the Z direction satisfy L1>L2.

(Explanation on Manufacturing Method)

[0613] As in the case of embodiment 5, in the case of production using injection molding, it is preferably a two-piece mold consisting of the cylindrical mold 660 and the mounting portion side mold 661 (shown in FIG. 62).

[0614] Similarly to Embodiment 5, the end of the insertion taper 673 and the end of the driving force receiving surface 673a are arranged at the same position in the Z direction, and the mold parting plane 662 at the engaging portion 673 is made straight.

[0615] The inner diameter of the portion where the root portion 674a of the flange member 670 is provided is set to be substantially the same as the inner diameter of the other portion as in Embodiment 5.

[0616] Similarly to Embodiment 5, the engaging portion 673 and the support 674 do not overlap with other portions on a projection plane of the flange member 670 projected perpendicularly to the rotation axis (Z direction) (as shown in FIG. 60).

(Description on Alignment Member)

[0617] As in Embodiment 5, the aligning member 633 is provided with an inverted conical shape 633a, a press-fitting portion 633b, a retaining portion 633c, and a convex portion 633d (shown in FIG. 63). The projecting portion 633d is a portion for matching the phases of the aligning member 633 and the flange member 670 with each other.

[0618] As in Embodiment 5, in the Z direction, the center 101h of the semispherical shape 101c of the main assembly driving shaft 101 is within the range of the driving force receiving surface 673a in a state in which the semispherical shape 101c is in contact with the contact portion 633e. The alignment member 633 is mounted to the flange member 670 (shown in FIG. 58) so as to satisfy the condition.

[0619] Further, as shown in FIG. 58, the flange member 670 is provided with a press-fitted portion 672a at a position corresponding to the press-fit portion 633b. The press-fitted portion 672a is disposed on the inner side (the Z2 direction side) of the photosensitive drum unit 30 with respect to the press-fit portion 672d in the Z direction. Thus, it is possible to suppress the influence of deformation due to press-fitting of the press-fit portion 672d on the press-fitted portion 672a. By this, the center of the inverted conical shape 33a and the center of the photosensitive drum 1 can be aligned with high accuracy.

[Engaging Process of Coupling Member to Main Assembly Drive Shaft]

[0620] A process of engagement of the coupling member 628 with the main assembly driving shaft 101 will be described in detail.

[0621] As shown in part (a) of FIG. 64, similarly to Embodiment 1, the coupling member 628 is inserted toward the main assembly driving shaft 101 in a state of inclination of approx. 0.5-2 degrees relative to the angle at the time when the cartridge 7 is positioned relative to the image forming apparatus main assembly 100A (shown in part (e) of FIG. 64).

[0622] First, as shown in part (b) of FIG. 64, the free end of the inner peripheral surface 671b of the cylindrical portion 671 of the flange member 670 abuts against the rough guide portion 101g of the main assembly driving shaft 101. The main assembly driving shaft 101 is configured to support the bearing portion 101d in the cantilever fashion. Therefore, similarly to Embodiment 5, the coupling 7 is inserted into the main assembly driving shaft 101 in a state that the rough guide portion 101g of the main assembly driving shaft 101 fits the inner peripheral surface 671b of the coupling member 670. Similarly to Embodiment 1, in the Z direction, the driving force receiving surface 673 of the engaging portion 673 has a length L2 which satisfy L1>L2, where L1 is a distance from the front end surface of the cylindrical portion 671 to the front end surface of the engaging portion 673 (as shown in FIG. 58). Therefore, similarly to Embodiment 5, it is possible to suppress the semispherical shape portion 101c at the free end of the main assembly driving shaft 101 from hitting a unintended part of the engagement portion 673 or the base portion 674. Thus, the engaging portion 673 and the base portion 674 can be protected.

[0623] When the coupling member 628 is further inserted toward the rear side of the main driving shaft 101 from the state shown in part (b) of FIG. 64, the mounting tapered surface 573d of the engagement portion 673 and the semispherical shape portion 101c of the free end of the main assembly driving shaft 101 are brought into contact to each other. Due to the inclined surface of the insertion tapered surface 573d and the spherical shape of the semispherical shape 101c, the main assembly driving shaft 101 is guided substantially to the center of the three engaging portions 673.

[0624] Similarly to Embodiment 5, when the coupling member 628 is further inserted into the main assembly driving shaft 101, the base portion 674 elastically deforms radially outward so that the engagement portion 673 follows the semispherical shape 101c. As a result, as shown in part (a) of FIG. 65, the engaging portion 673 moves (retracts) to the outer diameter of the shaft portion 101f of the main assembly driving shaft 101. By this movement, as shown in part (d) of FIG. 64, the coupling member 628 is mounted to the main assembly driving shaft 101 until the dismounting tapered surface 673e of the engagement portion 673 comes deeper in the Z direction than the main assembly side dismounting taper 101i of the main assembly driving shaft 101.

[0625] Thereafter, similarly to Embodiment 1, the cartridge 7 is lifted so that the drum unit bearing member 39L of the cartridge 7 abuts against the front side cartridge positioning portion 110. By thus lifting the cartridge 7, the cartridge 7 is positioned relative to the image forming apparatus main assembly 100A (as shown in part (d) of FIG. 21). By the operation of this cartridge 7, as shown in part (e) of FIG. 64, the inclination of the coupling member 628 is eliminated.

[0626] When the main assembly driving shaft 101 rotates, the phases of the main assembly drive transmission groove 101a and the engagement portion 673 are aligned as in the Embodiment 5. As a result, at least a part of the elastic deformation of the base portion 674 is eliminated, and a part of the free end side of the engagement portion 673 enters the main assembly drive transmission groove 101a. By this, the coupling member 628 and the main assembly driving shaft 101 are engaged (as shown in part (b) of FIG. 65).

[0627] When the phases of the main assembly drive transmission groove 101a and the engagement portion 673 are in phase alignment with each other, at least the elastic deformation of the base portion 674 is released at the stage of part (d) of FIG. 64, and the state of part (b) of FIG. 65 results.

[Driving of Coupling Member by Main Assembly Drive Shaft]

[0628] Similarly to Embodiment 1, the driving force receiving surface 673a has a twisted shape and is inclined with respect to the rotation axis of the flange member 670. This is employed in order that a force is produced for the reverse conical shape 633a of the aligning member 633 to assuredly contacts to the semispherical shape 101c of the free end of the main assembly driving shaft 101, when receiving driving force at the driving force receiving surface 673a from the main assembly driving shaft 101. The twisting direction is such that the outer side (the Z1 direction side) of the driving force receiving surface 673a is disposed upstream of the inner side (the Z2 direction side) with respect to the rotational direction of the photosensitive drum 1 (as shown in FIG. 66).

[0629] Similarly to Embodiment 5, as the flange member 670 is viewed along the Z direction, a straight line is drawn from the inner diameter end 673b of the driving force receiving surface 673a in a direction perpendicular to the driving force receiving surface 673a. With respect to the straight line, the root portion 674a is disposed on the upstream side in the rotational direction of the flange member 670 (FIG. 67). By doing so, when the driving force F1 is provided from the main assembly driving shaft 101, the winding portion 574b winds around the shaft portion 101f. Thus, similarly to Embodiment 5, even if the load received by the photosensitive drum unit 30 changes, the deformation amount of the base portion 574 is small, and therefore, the influence of deformation on the rotation of the photosensitive drum unit 30 can be suppressed to a small degree.

[0630] In addition, in this embodiment, in the Z direction, the root portion 674a of the base portion 674 is disposed at the same position as the press-fit portion 672d (shown in FIG. 59). That is, in the Z direction, the root portion 674a is disposed inside the photosensitive drum 1. That is, when the photosensitive drum (cylinder) 1 and the base portion 674 are projected onto the axis of the photosensitive drum 1, the projection area of the base portion 674a overlaps the projection area of the photosensitive drum 1 on the axis. In particular, in this embodiment, the entire projection area of the base portion 674 overlaps the projection area of the photosensitive drum 1. That is, the entire projection area of the base portion 674 is inside the projection area of the photosensitive drum 1.

[0631] Similarly, in the Z direction, the engaging portion 673 is disposed inside the photosensitive drum 1. That is, when the photosensitive drum 1 and the engaging portion 673 are projected onto the axis of the photosensitive drum 1, the projection area of the engaging portion 673 overlaps the projection area of the photosensitive drum 1 on the axis.

[0632] In Embodiment 5, the root portion 574a is disposed outside with respect to the Z direction beyond the mounting portion 572 (FIG. 59). However, with this structure, there is a likelihood that when the driving force receiving surface 573a receives the driving force F1 from the main assembly driving shaft 101, the cylindrical portion 571 between the root portion 574a and the press-fitting portion 572d may be twisted.

[0633] On the other hand, in the case that at least a part of the root portion 674a is arranged at the same position as the press-fit portion 672d in the Z direction as in this embodiment, the amount of the twisting deformation becomes small. This is because the press-fit portion 672d is covered by the photosensitive drum 1, so that even if a force is applied from the outside via the base portion 674a, the press-fit portion 672d is hardly deformed. That is, even if the driving force receiving surface 573a receives the driving force from the main assembly of the apparatus, the press-fitting portion 672 is less likely to be twisted and the cylindrical portion 671 is less likely to be twisted, if the root portion 674a is mounted to the press-fitting portion 672. namely, the amount of deformation of the flange member 670 can be suppressed to be small.

[0634] As a result, even if the load received by the photosensitive drum unit 30 changes, the deformation amount of the flange member 670 is small, and therefore, the influence of deformation on the rotation of the photosensitive drum unit 30 can be suppressed. As a result, the photosensitive drum 1 can be more stably driven.

[0635] Further, the engaging portion 673 (driving force receiving surface 673a) is disposed inside the photosensitive drum 1 in the Z direction. By employing this arrangement, the following effects can be provided.

[0636] When the positions of the main assembly driving shaft 101 and the coupling member 628 deviate due to the component part tolerances, the inclination of the main assembly driving shaft 101 is can be made small, if the drive force receiving surface 673a is disposed at a position far from the bearing portion 101d for the main assembly driving shaft 101. The driving force receiving surface 673a can be placed more inside the photosensitive drum 1 (in the Z direction) by placing the driving force receiving surface 673a inside the press-fit portion 672d as in this embodiment than by placing the driving force receiving surface 673a inside the cylindrical portion. With this arrangement, the inclination of the main assembly driving shaft 101 can be suppressed when the position of the coupling member 628 deviates relative to the positions of the main assembly driving shaft 101. As a result, the photosensitive drum 1 can be stably driven.

[Removal of Coupling Member from Main Assembly Driving Shaft]

[0637] Referring to FIG. 69, the removal operation of the coupling member will be described. As in Embodiment 5, the drive force receiving surface 673a and the main assembly drive transmission surface 101b are in contact with each other when the rotational drive of the main assembly driving shaft 101 is stopped. In this state, a part of the engagement portion 673 is in the main assembly drive transmission groove 101a (shown in part (a) of FIG. 68).

[0638] When the cartridge door 104 is opened, the lower front side cartridge guide 109 lowers, and the drum unit bearing member 39L separates from the front side cartridge positioning portion 110 of the image forming apparatus main assembly 100A. At this time, the coupling member 628 and the main assembly driving shaft 101 are inclined by about 0.5 to 2 degrees with relative to the mounting complete state (Z direction) as in Embodiment 5 (part (b) of FIG. 68).

[0639] When the cartridge 7 is started to be removed from the image forming apparatus main assembly 100A, the removed tapered surface 673e of the engaging portion 673 abuts against the main assembly side removed taper 101i, as in the Embodiment 5. When the dismounting tapered surface 673e abuts against the main assembly side dismounting taper 101i, the base portion 674 begins to elastically deform and moves the engaging portion 673 radially outward along the main assembly side dismounting taper 101i (part (c) of FIG. 68).

[0640] Further, when the coupling member 628 is disengaged from the main driving shaft 101, as in the Embodiment 5, the state is the same as in part (a) of FIG. 65, in which the base portion 674 is further elastically deformed, and the engagement portion 673 is moved to the outer diameter of the shaft portion 101f of the shaft 101. As the engaging portion 673 moves to the outer diameter of the shaft portion 101f, the engagement between the engaging portion 673 and the main assembly drive transmission groove 101a is canceled (eliminated). In this case, as shown in part (d) of FIG. 68, the coupling member 628 can be removed from the main assembly driving shaft 101.

[0641] Further, when the coupling member 628 is removed from the main assembly driving shaft 101, as shown in part (e) of FIG. 68, the elastic deformation of the base portion 674 is released and the position of the engagement portion 673 returns to the position before the elastic deformation.

[0642] With the above-described operation, the coupling member 628 can be removed from the main assembly driving shaft 101.

[Insert Molding of Flange Member]

[0643] The material, shape, and manufacturing method of the coupling member 628 may be appropriately selected if the mountability and drive transmission are stable. In particular, when mass production is taken into consideration, it is preferable to use a resin material.

[0644] Specifically, by forming the coupling member 628 using the resin materials (POM, PPS, PS, nylon, etc.) exemplified below, it is possible to provide a result satisfactorily meeting the drive transmission property and the mountability to the device main assembly.

[0645] Under such circumstances, the result of investigation the further improvement of the performance of the coupling member will be described below.

[0646] The apparatus may be kept unoperated under a high temperature condition in this state that the engagement portion 673 of the flange member 670 and the main assembly drive transmission groove 101a of the main assembly driving shaft 101 are not in phase with each other, that is, the base portion 674 is left in a state of being elastically deformed. If this state continues, creep deformation may occur in the base portion 674. The amount of creep deformation depends on the stress applied to the base and the ambient temperature, and therefore, the amount of creep deformation varies depending on the straight thickness 674l of the base portion and the material of the resin. In such special circumstances, the results of deep investigations for further improvement of reliability will be described below.

[0647] FIG. 69 in an illustration illustrating a situation occurring when the creep deformation of the base portion 3674 is large. Specifically, this Figure shows a state in which the inner diameter end 3673b of the driving force receiving surface 3673a is deformed radially outward to the extent of the position contacting the relief portion 101j. For example, when a resin material having a large creep deformation is used, creep deformation of the base portion 3674 proceeds, even to the extent that even when the main assembly driving shaft 101 rotates, the engagement portion 3673 can not be pulled inward in the radial direction in some cases. In other words, there is a likelihood that the photoconductive drum 1 can not be rotated stably, or the photoconductive drum 1 can not be driven.

[0648] Therefore, in order to suppress creep deformation, sheet metal (metal plate, plate-like metal) was inserted as an auxiliary member inside the resin material. As a result, it was possible to suppress the creep deformation as compared with the structure formed only with the resin. In addition, as long as the resin material has excellent creep resistance such as POM and PPS, the result that sufficient reliability can be ensured without placing an auxiliary member inside the resin was obtained.

[0649] Condition 1: POM (LC750 available from Asahi Kasei Chemicals Corporation, Japan): Stainless steel sheet metal having a thickness of 0.2 mm inside.

[0650] Condition 2: PPS (Torelina A900 available from Toray Industries, Inc., Japan).

[0651] Condition 3: POM (LC750 available from Asahi Kasei Chemicals Corporation, Japan).

[0652] Condition 4: PS (VS142 available from PS Japan): Stainless steel sheet metal having a thickness of 0.2 mm inside.

[0653] Condition 5: PS (VS142 a veritable from PS Japan).

[0654] When the engagement portion 673 of the flange member 670 and the main assembly drive transmission groove 101a of the main assembly drive transmission shaft 101 were not in phase alignment with each other and were stored in a high temperature environment (three days at 50 degrees C.), and the results were that no large creep deformation occurred, in the above-described conditions 1 to 4. Specifically, no creep deformation that had a large influence on drive transmission was observed. However, when resin material with low creep resistance like PS was used, the result was that the creep deformation affected on driving force transmission (condition 5). Nevertheless, it is possible to suppress creep deformation by reinforcement with a sheet metal made of stainless steel as a reinforcing member (auxiliary member) even though the material PS has low load deflection temperature (condition 4).

[0655] That is, even if the base portion 674 is made of only the resin material, it was sufficiently resistant to creep deformation without a inserted reinforcing member, if the material has a sufficient creep resistance. It is preferable to insert an auxiliary member in order to ensure high reliability even in a case of receiving in a higher temperature environment for a longer period of time. In other words, it can be said it is preferable that the resin material that is excellent in creep resistance like POM is reinforced with stainless steel sheet metal as in Condition 1, from the standpoint of suppressing the creep deformation. namely, it is possible to prevent the engagement of the driving force receiving surface 673a with the main assembly drive transmission surface 101b from becoming shallow, thus reliably engaging with the main assembly driving shaft 101.

[0656] Hereinafter, a structure for insert-forming the sheet metal member 635 in the flange member 670 will be described in detail.

[0657] In this embodiment, three sheet metal members 635 (sheet metal made of stainless steel) as reinforcing members are equally arranged in the circumferential direction of the flange member. The sheet metal member 635 is a member formed by machining a metal plate (metal plate), and is a plate made of stainless steel, that is, an alloy plate mainly made of iron. The sheet metal member 635 is not necessarily made of stainless steel or iron, but may be made of another material.

[0658] As shown in FIG. 70, the sheet metal member 635 has a base inside portion 635a, an engagement portion inside portion 635c, a flange portion inside portion 635b, and a connecting portion 635d.

[0659] The flange inner portion 635b is sandwiched between the cylindrical mold 660 and the mounting portion side mold 661 at the parting plane 662. This is done in order to stably mount the sheet metal member 635 to the flange member 670 in the Z direction of the flange member 670. In addition, the portion (the pressed portion 635h) which is sandwiched by the metal molds is configured to be exposed from the resin. That is, the sheet metal member 635 has a portion exposed from the resin portion.

[0660] Further, as shown in FIG. 71, one of the pressed portions 635h is disposed at a position shifted in phase by 90 degrees as viewed from the clamp groove 672e. Therefore, the clamp groove 672e and the pressed portion 635h can be arranged so as not to overlap with each other in the circumferential direction. As shown in FIG. 29, the flange portion inner portion 635b is arranged perpendicular to the base inner portion 635a disposed in the base portion 674. The flange member 670 has three cut-away portions 675a in the flange 675. Then, the pressed portion 635h is disposed within a range where the cut-away portion is provided. The cut-away portions 675a are equally arranged in the circumferential direction, and one of the cut-away portions 675a is disposed at a position perpendicular to the clamp groove 72e.

[0661] The base inner portion 635a comprises a straight portion inside portion 635e and a winding portion inside portion 635f inside the winding portion 674b (inside the straight portion 674c of the base portion 674) (as shown in FIG. 72).

[0662] The winding portion inner portion 635f may not have a R shape corresponding to the winding portion 674b but may have a straight shape as shown in FIG. 72.

[0663] Further, as shown in FIG. 72, the connection holes (through holes) 635g formed in the base inside 635a can be connected with the resin on the front and rear surfaces of the metal plate to increase the bonding force between the resin and the metal. That is, the communication hole 63g is a hole in which the resin is provided.

[0664] In order to prevent the base inner portion 635a from being deformed by the resin pressure at the time of injection molding, and in order to hold the base inside portion 635a by the cylindrical portion side mold 660 and the mounting portion side 661 described above, the base inner portion 635a is exposed at a part of the base portion 674. This increases the accuracy of forming the base portion 674.

[0665] Specifically, as shown in FIGS. 72 and 73, a straight part cut-away portion 674g and a winding part cut-away portion 674h are provided in the resin molded part of the straight part inside 635e and the winding part inside 635f, respectively. The straight portion exposed portion 635i exposed to the outside of the resin portion, and the winding portion exposed portion 635j are included in the base inner portion 635a.

[0666] The straight portion exposed portion 635i and the winding portion exposed portion 635j are sandwiched between the cylindrical portion side mold 660 and the mounting portion side mold 661. By this, it is made possible to suppress deformation of the base interior 635a by the resin pressure during injection molding.

[0667] Also, as shown in FIGS. 74 and 75, the straight portion cut-away portion 674g and the winding portion cut-away portion 674h have straight portion cut-away portion tapered surface 674i and a winding portion cut-away portion tapered surface 674j, respectively. The cylindrical portion side mold 660 and the mounting portion side mold 661 have tapered shapes corresponding to the shapes of the straight portion cut-away portion tapered surface 674i and the winding portion cut-away portion tapered surface 674j, respectively. Therefore, even if some misalignment occurs with respect to the corresponding groove shape of the metal mold due to the dimensional tolerance of the metal plate member 635, the taper shapes of the cylindrical part side mold 660 and the attachment part side mold 661 is capable of guiding to the predetermined position of the mold (corresponding groove shape of the mold). As a result, when the resin portion is molded, the engaging portion inside portion 635a is disposed inside the engaging portion 673.

[0668] As shown in FIG. 73, the connecting portion 635d has a shape for connecting the base inside portion 635a and the flange portion inside portion 635b.

[0669] The above is a description of a structure for insert molding the sheet metal 635 into the flange member 670.

[0670] Also, the above-described embodiments and the embodiments which will be described hereinafter, insert molding may be used in order to obtain good creep properties as in this embodiment.

[0671] Referring to FIG. 76, Embodiment 7 will be described.

[0672] In this embodiment, a part of the driving force receiving portion and a part of the supporting portions (the engaging portion 673 and the base portion 674) for supporting the driving force receiving portion are provided inside the photosensitive drum 1.

[0673] Elements corresponding to those of the above-described embodiment (particularly, the Embodiment 6) are assigned by the same names, and descriptions of the similar points to those of the above-described elements may be omitted. The description will be made mainly about the differences from the abovementioned elements.

[0674] In Embodiment 6, in the Z direction, the root portion 674a of the base portion 674 is disposed at the same position as the press-fit portion 672d (shown in FIG. 59).

[0675] On the other hand, in this embodiment, in the Z direction, a part of the base portion 774a is mounted to the press-fit portion 772d. That is, when the base portion 674 and the photosensitive drum 1 are projected onto the axis of the photosensitive drum 1, a part of the projection area of the base portion 774a overlaps a part of the projection area of the photosensitive drum 1. On the other hand, a part of the projection area of the root portion 774a is located outside the projection area of the photosensitive drum 1.

[0676] Also with this structure, although not as much as in Embodiment 6, it is possible to suppress twisting deformation of the cylindrical portion 771 when the driving force F1 is received by the driving force receiving surface (driving force receiving portion) 773a, and the information amount of the flange member 70 can be suppressed to be small. As a result, even if the load on the photosensitive drum unit 30 changes, the influence of deformation on the rotation of the photosensitive drum unit 30 can be suppressed to a small extent. As a result, the photosensitive drum 1 can be stably driven.

[0677] Referring to FIGS. 77A, 77B, 88, and 79, Embodiment 8 will be described.

[0678] In this embodiment, the supporting portions (the engaging portion 873 and the base portion 874) for supporting the driving force receiving portion 873a extend in the circumferential direction of the coupling member, while the supporting portion also extends in the axial direction of the coupling member.

[0679] Elements corresponding to those of the above-described embodiment (particularly, the Embodiment 5) are assigned by the same names, and descriptions of the similar points to those of the above-described elements may be omitted. The description will be made mainly about the differences from the abovementioned elements.

[0680] In Embodiment 5, the driving force receiving surface 573a and the base portion 574a of the base portion 574 are disposed on the inner peripheral surface 571b of the cylindrical portion 571 in the Z direction (as shown in FIG. 39). Also, as shown in FIG. 45, the root portion 574a of the base portion 574 is arranged so as to overlap the entire area of the driving force receiving surface 573a in the Z direction. That is, the straight line connecting the rear end (root portion 574a) of the base portion 574 and the tip (driving force receiving surface 573a) is substantially perpendicular to the axis (Z direction) of the flange member. That is, the base portion 574 is inclined by about 90 degrees with respect to the Z direction (axial line).

[0681] In contrast, in this embodiment, the direction in which the base portion 874 extends is inclined with respect to the direction perpendicular to the Z direction. In other words, the base portion 874 extends at least in the circumferential direction of the coupling member, but the extending direction thereof is not parallel to the circumferential direction. The base portion 874 extends in the circumferential direction of the coupling member, but also extends in the axial direction of the coupling member. As a result, the base portion 874 is inclined with respect to the circumferential direction of the coupling member.

[0682] Further, in the Z direction, the base portion 874a of the base portion 874 is arranged so that the winding portion 874b and a part thereof overlap with each other.

[0683] In the Z direction, the driving force receiving surface 873a and the root portion 874a are disposed inside the cylindrical portion 871 in the same manner as in Embodiment 5.

[0684] As in Embodiment 5, when the driving force F1 is received by the driving force receiving surface 873a, the winding portion 874b winds on the shaft portion 101f of the main assembly driving shaft 101, and the winding portion 874b rotates integrally with the shaft portion 101f to receive the rotational force Fc produced by the driving force F1 by the straight portion 874c.

[0685] FIG. 78 shows a case where the root portion 3874a of the base portion 3874 does not completely overlap the winding portion 3874b, unlike this embodiment. When the straight portion 3874c receives the rotational force Fc, the root portion 3874a receives the reaction force −Fc of the force Fc. The straight portion 3874c is pulled by the rotational force Fc and the reaction force −Fc, so that the inclination of the straight portion 3874c is made gentler in a direction perpendicular to the Z direction. After the inclination of the straight portion 3874c becomes gentle, the rotational force Fc is transmitted to the photosensitive drum 1 via the cylindrical portion 3871 and the mounting portion 872.

[0686] As a result, when the load received by the photosensitive drum unit 30 is changed and therefore the rotational force Fc is changed, the deformation amount of the base portion 3874 changes, so that the influence on the rotation of the photosensitive drum unit 30 is larger than in this embodiment.

[0687] On the other hand, according to the structure of this embodiment, the root portion 874a has a portion overlapping with the winding portion 874b in the Z direction. That is, when the winding portion 874b and the base portion 874a are projected onto the axis line of the drum unit 30, at least a part of the projection area of the winding portion 874b and at least a part of the projection area of the base portion 874b overlap with each other.

[0688] In this way, as shown in FIG. 79, when the rotational force Fc is received, the receiving portion is at the overlapping root portion 874a. Therefore, the rotational force Fc can be transmitted to the cylindrical portion 871 substantially without deformation in the direction of making the inclination of the straight portion 874c gentle relative to the direction perpendicular to the Z direction. As a result, even if the load received by the photosensitive drum unit 30 changes, the influence on the rotation of the photosensitive drum unit 30 can be reduced.

[0689] In order to wind the base portion 874 on the main assembly driving shaft 101 as in this embodiment, the base portion 874 is desirably inclined by 30 degrees to 90 degrees (not less than 30 degrees and not more than 90 degrees) with respect to the Z-axis direction (the axis Ax of the coupling member). A more preferable range is within a range of 50 degrees to 90 degrees (50 degrees to 90 degrees).

[0690] The inclination of the base portion 874 (supporting portion of the driving force receiving portion) with respect to the axis Ax of the coupling member is determined as follows.

[0691] The cross section of the coupling member take an along a plane including the fixed end (root portion 874a) of the base portion 874 and the axis Ax of the coupling member pass (FIG. 79) is taken. In this cross section, the angle between the base portion 874 and the axis Ax is to be viewed. FIG. 79, an angle formed between a straight line extending from the fixed end (base portion 874a) of the base portion 874 to the free end (engagement portion 873) and a straight line extending from the fixed end (874a) parallel to the axis Ax along the left side face of the base portion 874 is in the angle to be determined. On FIG. 79, the angle is measured to be about 36 degrees.

[0692] In this embodiment, the base portion 874 is deviated so that the free end thereof is disposed outside the fixed end in the axial direction (arrow Z1 side).

[0693] However, the base portion 874 may be inclined so that the free end thereof is disposed on the inner side in the axial direction (on the arrow Z2 side) than the fixed end. In this case, the inclination of the base portion 874 (supporting portion of the driving force receiving portion) with respect to the axis line Ax may be defined as follows. The angle formed between the straight line extending from the fixed end to the free end of the base portion 874 along the right side face of the base portion 874 and the straight line extending from the fixed end in parallel to the axis Ax is the angle to be determined.

[0694] That is, the angle is measured so that the base portion 874 is always 90 degrees or less with respect to the axis Ax.

[0695] Referring to FIG. 80 to FIG. 82, Embodiment 9 will be described.

[0696] In this embodiment, the fixed end (root portion 974a) of the base portion 974 is disposed inside the photosensitive drum 1, while at least a part of the driving force receiving surface 673a and the engaging portion 673 is disposed in the photosensitive drum 1.

[0697] Elements corresponding to those of the above-described embodiment (particularly, the Embodiment 6) are assigned by the same names, and descriptions of the similar points to those of the above-described elements may be omitted. The description will be made mainly about the differences from the abovementioned elements.

[0698] In Embodiment 6, the driving force receiving surface 673a and the base portion 674a of the base portion 674 are arranged on the inner peripheral surface 672h of the mounting portion 672 in the Z direction (as shown in FIG. 59). In addition, the root portion 674a of the base portion 674 is disposed so as to overlap with the entire area of the driving force receiving surface 673a in the Z direction. That is, the entirety of the driving force receiving surface 673a and the entire supporting portion for supporting the driving force receiving surface 673a are disposed inside the photosensitive drum 1.

[0699] On the other hand, in this embodiment, as shown in FIG. 80, the base portion 974 is inclined with respect to the direction perpendicular to the Z direction, and the root portion 974a of the base portion 974 is formed such that the winding portion 974b and a part thereof overlap with each other in the Z direction. In the Z direction, the base portion 974a is disposed on the inner peripheral surface 972h of the mounting portion 972 as in Embodiment 6.

[0700] The effect of arranging the base portion 974a so that a part of the base portion 974a overlaps the winding portion 974b in the Z direction is similar to that of Embodiment 8. Furthermore, the effect that the root portion 974a is arranged on the inner peripheral surface 972h of the mounting portion 972 in the Z direction is the same as the of Embodiment 6 as compared with Embodiment 5, and the present embodiment has the same effect as the Embodiment 8.

[0701] As shown in FIG. 81, even if the driving force receiving surface (driving force receiving portion) 973a is disposed on the inner peripheral surface 972h of the mounting portion 972 in the Z direction, the same effect can be provided.

[0702] As shown in FIG. 82, also in the structure in which a part of the root portion 974a overlaps the inner peripheral surface 972h of the mounting portion 972 in the Z direction, the effect similar to that of the Embodiment 7 as compared with Embodiment 5 can be provided on this embodiment.

[0703] Referring to FIGS. 83 to 86, an Embodiment 10 will be described. Elements corresponding to those of the above-described embodiment (particularly, the Embodiment 6) are assigned by the same names, and descriptions of the similar points to those of the above-described elements may be omitted. The description will be made mainly about the differences from the abovementioned elements. In Embodiment 6, as shown in FIG. 60, the engaging portion 673 and the base portion 674 are equally arranged in three positions in the circumferential direction of the flange member 670.

[0704] In this embodiment, as shown in FIG. 83, the engaging portion 1073 and the base portion 1074 are provided at one position. The engaging portion 1073 is provided with a driving force receiving surface (driving force receiving portion) 1073a. The engaging portion 1073 and the base portion 1074 are support portions for supporting the driving force receiving portion.

[0705] A force receiving portion 1077 is provided to suppress the main assembly driving shaft 101 from tilting too much by the elastic deformation force of the base portion 1074 when the coupling member 1028 is mounted to the main assembly driving shaft 101.

[0706] More specifically, in a process of engaging the coupling member 1028 to the main driving shaft 101, the base portion 1074 is elastically deformed, and the engagement portion 1073 moves radially outward. At this time, the shaft portion 101f of the main assembly driving shaft 101 is pushed to the opposite side by the elastic deformation force of the base portion 1074. At this time, as shown in FIG. 84, the force receiving portion 1077 is brought into contact with the shaft portion 101f to suppress the main assembly driving shaft 101 from tilting too much. As a result, the force receiving portion 1077 keeps a satisfactory mountability of the cartridge 7 to the image forming apparatus main assembly 100A.

[0707] In a state before elastic deformation of the base portion 1074, at least a part of the insertion tapered surface 1073d and at least a part of the flange member 1070 are opposed to each other with the axis line of the flange member 1077 therebetween (FIG. 83). Similarly, in the state of elastic deformation of the base portion 1074 occurred, at least a part of the driving force receiving surface and at least a part of the force receiving portion 1077 are opposed to each other with the axis line therebetween (as shown in FIG. 84).

[0708] As shown in FIG. 85, the alignment of the coupling member 1028 and the main assembly driving shaft 101 is performed by the alignment member 1033 having an inverted conical shape portion 1033a as in Embodiment 6. At this time, the radius R3 of the force receiving portion 1077 is larger than the radius R2 of the shaft portion 101f, and the force receiving portion 1077 does not abut to the shaft portion 101f.

[0709] As shown in FIG. 84, the position of the force receiving portion 1077 in the Z direction is the same as that of the engaging portion 1073.

[0710] In this embodiment, the engaging portion 1073 and the root portion 1074a of the base portion 1074 are disposed inside the mounting portion 1072 in the Z direction as in Embodiment 6. However, as in Embodiment 5, it may be disposed in the cylindrical part 1071 (part (a) of FIG. 86), or a part of the root part 1074a may be mounted in the range of the press-fitting part 1072d as in Embodiment 7 (part (b) of FIG. 86). As in Embodiments 8 and 9, the base portion may be inclined with respect to the direction perpendicular to the Z direction, and in the Z direction, the root portion 1074a of the base portion 1074 may overlap with the winding portion 1074b and a part thereof (parts (c), (d), (e) and (f) of FIG. 86).

[0711] Referring to FIGS. 87A, 87B, 88, and 89, Embodiment 11 will be described.

[0712] Elements corresponding to those of the above-described embodiment (particularly, the Embodiment 6) are assigned by the same names, and descriptions of the similar points to those of the above-described elements may be omitted. The description will be made mainly about the differences from the abovementioned elements. In Embodiment 6, as shown in FIG. 60, the engaging portion 673 and the base portion 674 are uniformly arranged in three positions in the circumferential direction of the flange member 670, and as shown in FIG. 58, the coupling member 628 includes the flange member 670 and the aligning member 633.

[0713] On the other hand, in this embodiment, as shown in FIGS. 87A and 87B, one coupling portion 1173 and one base portion 1174 are provided in the coupling member 1128. The engaging portion 1173 is provided with a driving force receiving portion. The engaging portion 1173 and the base portion 1174 are support portions that movably support the driving force receiving portion.

[0714] As shown in FIGS. 87A, 87B, 88 and 89, the coupling member 1128 is provided with a radial direction positioning portion 1076a, having substantially the same diameter as that of the shaft portion 101f of the main assembly driving shaft 101 at the position different from the engaging portion 1173 and from the base portion 1174 in the circumferential direction. Also, it is provided with an abutment portion 1076b for being contacted by the semispherical shape 101c of the free end of the main assembly driving shaft 101 when the driving of the main assembly driving shaft 101 is transmitted to the coupling member 228.

[0715] By this, the two parts, namely the flange member 670 and the aligning member 633 in Embodiment 6 are constituted by one part.

[0716] As shown in FIG. 87A, three radial positioning portions 1176a are arranged in the circumferential direction. The angle formed the angle of the line connecting the outer end of the radial positioning portion 1176a and the axis center of the flange is larger than 180 degrees and is disposed at a position other than 120 degrees and 240 degrees positions from the engaging portion 1173. As described in Embodiment 1, the main assembly drive transmission grooves 101a are uniformly arranged at three positions (120 degree spacing, substantially equally spaced) in the circumferential direction on the shaft portion 101f of the main assembly driving shaft 101. As in the Embodiment 1, after one of the main assembly drive transmission grooves 101a of the main assembly driving shaft 101 and the engagement portion 1173 are in phase alignment with each other, the drive force receiving surface 1173a of the main assembly drive transmission surface 101b is brought into contact thereto, by which the driving force is transmitted from the main assembly driving shaft 101 to the coupling member 1128.

[0717] At this time, the radial direction positioning portion 1076a takes the position different from those of the three main assembly drive transmission grooves 101a equally provided on the shaft portion 101f of the main assembly driving shaft 101. The radial direction positioning portion 1076a does not enter the driving transmission groove 101a. Therefore, the radial positioning portion 1176a is positioned in the radial direction on the shaft portion 101f without being affected by the two main assembly drive transmission grooves 101a not engaged with the driving force receiving surface 1173.

[0718] Further, as shown in FIG. 88, the radial positioning portion 1176a is disposed at the same position as the driving force receiving surface 1173a in the Z direction.

[0719] In Embodiment 6, the flange member 670 and the aligning member 633 are constituted by two parts, but in this embodiment, it can be constituted by one part in the above-described manner.

[0720] As shown in FIG. 87A, as viewed in Z direction, the abutment portion 1176b does not have a portion overlapping with the projection plane of the engaging portion 1173, the base portion 1174, and the radial positioning portion 1176a or about 1 mm around the projection plane. Therefore, similarly to the flange member 670 of the Embodiment 6, the coupling member 1128 can be injection-molded with a die of a two-piece construction including the cylindrical side mold and the mounting portion side mold.

[0721] In this embodiment, the engaging portion 1173 and the root portion 1174a of the base portion 1174 are disposed inside the mounting portion 1172 in the Z direction as in Embodiment 6. However, as in Embodiment 5, it may be disposed in the cylindrical portion 1171 (shown in part (a) of FIG. 90), or a part of the root portion 1174a is in the press-fit portion 1172d as in Embodiment 7 (shown in part (b) of FIG. 90). Also, as in Embodiments 8 and 9, the base portion may be inclined with respect to the direction perpendicular to the Z direction, and in the Z direction, the root portion 1174a of the base portion 1174 may partly overlap the winding portion 1174b (parts (c), (d), (e) and (f) of FIG. 90).