CARTRIDGE AND IMAGE FORMING APPARATUS

[0001] The present invention relates to a process cartridge detachably mountable to an image forming apparatus and relates to the image forming apparatus.

[0002] In an electrophotographic image forming apparatus using an electrophotographic image forming process, an electrophotographic photosensitive member and a process means actable on the photosensitive member are integrally assembled into a unit to prepare a process cartridge. Further, a type in which this process cartridge is made detachably mountable to a main assembly of the image forming apparatus is employed.

[0003] In such a process cartridge, in order to prevent leakage of a developer (toner) to an outside of the process cartridge, a constitution in which sealing with a plurality of seal members is made between cartridge frames constituting the process cartridge and between parts constituting the process cartridge is employed.

[0004] As the seal member, an elastic member such as an urethane foam, a soft rubber or an elastomer resin material is used. Further, the seal member is bonded with accuracy at connecting portions between the frames and between the parts.

[0005] In recent years, in order to realize cost reduction by an increase in manufacturing efficiency and to realize quality stability during assembling, the process cartridge has been manufactured by an automatic machine using devices in respective assembling steps without performing a manual assembling operation. Further, with respect to the seal member described above, from a viewpoint of an assembling property by the automatic machine, a constitution in which the seal member is directly formed on the cartridge frame by two-color (coinjection) molding or the like has been proposed (Japanese Laid-Open Patent Application (JP-A) Hei 7-121085).

[0006] However, in this conventional proposal, there was the following problem. That is, in the case where the seal member is molded on the cartridge frame by using the two-color molding, due to a constraint by a mold constitution such as a mold removing direction, a shape of the seal member is limited, and therefore it is difficult to form the seal member having a shape satisfying a necessary function. Further, in order to solve such a problem, a type in which the seal member is directly formed on the cartridge frame by bringing a mold later in contact with a molded cartridge frame and by bringing a gate portion of a resin material injecting device into contact with a resin material injecting port for injecting a melted resin material into the mold, and then by injecting the resin material into a space between the mold and the cartridge frame has been proposed.

[0007] In this case, a seal portion and a projected sprue (projected injected resin portion or molded portion) are formed, but as shown in FIG. 17, when the resin material is injected from a projected sprue 98b to an end portion 98a of a seal portion 98, a projection-shaped stepped portion is formed between the end portion 98a and the sprue 98b. The end portion 98a of the seal portion 98 is a seal function portion contactable to another part in order to seal (confine) the toner, and therefore when the projection-shaped stepped portion is formed at the end portion 98a contactable to another part, there is a fear that a sealing property is worsen and thus the toner is leaked out. Further, it would be also considered that the sprue 98b is provided in a position different from a position of the end portion 98a, but in that case, in order to maintain strength of the mold, there is a need to form the sprue 98b in a spaced state from the end portion 98a to some extent, so that there is a problem that an increase in size of the seal member is invited.

[0008] Therefore, a principal object of the present invention is to provide a cartridge and an image forming apparatus which are capable of improving a sealing property while suppressing an increase in size of a seal member.

[0009] According to an aspect of the present invention, there is provided a cartridge detachably mountable to a main assembly of an image forming apparatus, comprising: a frame; an accommodating portion, constituted by the frame, for accommodating a developer; a seal portion for preventing the developer from being leaking out from the accommodating portion, wherein the seal portion is formed by injection molding at a seal forming portion provided on the frame and is projected from the seal forming portion; and a sprue which is formed integrally with the seal portion by a resin material remaining in a path for permitting flow of the resin material melted when the seal portion is formed by the injection molding and which is projected from the frame in a position different from a position of the seal portion so as to be higher than the seal portion on the basis of the frame.

[0010] According to another aspect of the present invention, there is provided an image forming apparatus for forming an image on a recording material, comprising: a frame; an accommodating portion, constituted by the frame, for accommodating a developer; a seal portion for preventing the developer from being leaking out from the accommodating portion, wherein the seal portion is formed by injection molding at a seal forming portion provided on the frame and is projected from the seal forming portion; and a sprue which is formed integrally with the seal portion by a resin material remaining in a path for permitting flow of the resin material melted when the seal portion is formed by the injection molding and which is projected from the frame in a position different from a position of the seal portion so as to be higher than the seal portion on the basis of the frame.

[0011] These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.

[0029] With reference to the drawings, embodiments for carrying out the present invention will be described below. However, dimensions, materials, shapes and relative arrangement of constituent elements described in the following embodiments should be appropriately changed depending on structure and various conditions of devices (apparatuses) to which the present invention is to be applied, and therefore the scope of the present invention is not intended to be limited to the following embodiments.

[0030] First, with reference to FIG. 1, a general structure of a laser beam printer as an electrophotographic image forming apparatus 100 in an embodiment of the present invention. FIG. 1 is a schematic sectional view showing the general structure of the image forming apparatus in this embodiment. Incidentally, in the following description, a longitudinal refers to an axial direction (crossing a direction in which a process cartridge 2 is to be mounted in an image forming apparatus main assembly 100A) of a rotation shaft of a photosensitive drum 21.

[0031] In this embodiment, as shown in FIG. 1, in the image forming apparatus main assembly 100A, four independent process cartridges 2 (2Y, 2M, 2C, 2Bk) which are detachably mountable to the main assembly 100A are arranged in a vertical direction. The process cartridges 2 (2Y, 2M, 2, 2Bk) constitute image forming means for toners of yellow (Y), magenta (M), cyan (C) and black (Bk), respectively.

[0032] The process cartridges 2 (2Y, 2M, 2C, 2Bk) include rotation drum type electrophotographic photosensitive members (photosensitive drums) 21 (21Y, 21M, 21C, 21Bk), respectively, as an image bearing member. At a periphery of the photosensitive drums 21, charging rollers 23 (23Y, 23M, 23C, 23Bk) as a charging means and developing units 2b (2bY, 2bM, 2bC, 2bBk) each constituting a developing means are provided.

[0033] Further, at the periphery of the photosensitive drums 21, cleaning units 2a (2aY, 2aM, 2aC, 2aBk) including cleaning blades 28 (28Y, 28M, 28C, 28Bk), respectively, as a cleaning member are provided. In this way, in this embodiment, each photosensitive drum 21 is, together with the charging roller 23, integrally mounted in the cleaning unit 2a. That is, the cleaning unit 2a is also a photosensitive drum unit. In other words, in this embodiment, the photosensitive drum unit 2a including the photosensitive drum 21, the charging roller 23 and the cleaning blade 28 and the developing unit 2b are integrally assembled into a cartridge to form the process cartridge 2 (2Y, 2M, 2C, 2Bk).

[0034] The process cartridges 2 (2Y, 2M, 2C, 2Bk) for the four colors are constituted so as to be independently detachably mountable to the image forming apparatus main assembly 100A. Further, developer images (toner images) different in color are successively transferred superposedly onto an intermediary transfer belt 35, as an intermediary transfer member constituting a transfer device 5, by primary transfer rollers 34. As a result, a full-color image is formed on the intermediary transfer belt 35. The intermediary transfer belt 35 is wound around rollers 31, 32 and 33 provided in the transfer device 5, and is provided rotatably in an arrow A direction in FIG. 1. A transfer material P such as paper is fed from a sheet feeding cassette 7 provided at a lower portion of the image forming apparatus main assembly 100A and is conveyed in an upward direction, and then the full-color image on the intermediary transfer belt 35 is collectively transferred onto the transfer material P. Then, the transfer material P is subjected to fixing of the full-color image by a fixing device 50, and thereafter is discharged onto a sheet discharge tray 56 by a group of discharging rollers 53, 54 and 55.

[0035] Next, an operation in the case where image formation is effected by the above-constituted image forming apparatus will be described. First, a sheet of the transfer material P in the sheet feeding cassette 7 is separated by rotating a sheet feeding roller 41, and is conveyed to a registration roller pair 44. On the other hand, the photosensitive drums 21 and the intermediary transfer belt 35 are rotated at predetermined outer peripheral speeds (process speeds) in directions of arrows in FIG. 1. The surfaces of the photosensitive drums 21 electrically charged uniformly by the charging rollers 23 are exposed to laser beams 10 (10Y, 10M, 10C, 10Bk) from scanner portions as exposure devices 1 (1Y, 1M, 1C, 1Bk). Then, electrostatic latent images are formed on the photosensitive drums 21.

[0036] Image forming operations for the respective colors are the same, and therefore in the following, the image forming operation for yellow (Y) will be described. The surface of the photosensitive drum 21Y is irradiated with the laser beam 10Y for an yellow image by the scanner portion 1Y, so that the electrostatic latent image for yellow is formed on the photosensitive drum 21Y. Concurrently with this latent image formation, the electrostatic latent image on the photosensitive drum 21Y is developed with a yellow toner. At the same time, at a primary transfer position T1 downstream of a developing portion, the yellow toner image on the photosensitive drum 21Y is primary-transferred onto an outer peripheral surface of the intermediary transfer belt 35.

[0037] Similarly as described above, also with respect to a magenta image, a cyan image and a black image, latent image formation, development and toner image transfer onto the intermediary transfer belt 35 are performed, so that the full-color image consisting of the four types of the toner images of yellow, magenta, cyan and black is formed on the surface of the intermediary transfer belt 35. Concurrently with press-contact with the transfer material P, at a secondary transfer position T2, of the intermediary transfer belt 35 on which the primary transfer of the black toner image for the fourth color is ended and thus the full-color image is formed, a bias is applied to a transfer roller 51. As a result, the four color toner images constituting the full-color image are collectively transferred from the intermediary transfer belt 35 onto the transfer material P at the same time. Thereafter, the transfer material P is separated from the intermediary transfer belt 35 and is conveyed to the fixing device 50. Then, the transfer material P on which the toner image is fixed is discharged onto the discharge tray 56, provided at an upper portion of the main assembly, via the group of discharging rollers (roller pairs) 53, 54 and 55 with an image formation surface downward, so that the image forming operation is ended.

[0038] Next, the process cartridges 2 (2Y, 2M, 2C, 2Bk) in this embodiment will be described with reference to FIG. 2. FIG. 2 is a schematic sectional view of the process cartridge in this embodiment. Incidentally, the process cartridges for the respective colors of yellow, magenta, cyan and black have the same structure. Accordingly, in the following description, suffixes of Y, M, C and Bk for representing the respective colors are omitted, and the process cartridges 2 (2Y, 2M, 2C, 2Bk) for the respective colors will be collectively described as the process cartridge 2.

[0039] The process cartridge 2 is, as described above, divided into the cleaning unit, i.e., the photosensitive drum unit 2a and the developing unit 2b. The photosensitive drum unit 2a includes the photosensitive drum 21, the charging roller 23 as the charging means, and the cleaning blade 28 as the cleaning means (member). Further, the developing unit 2b is constituted by a developing device (developing means) for developing the electrostatic latent image on the photosensitive drum 21.

[0040] Further, in the photosensitive drum unit 2a, the photosensitive drum 21 is mounted rotatably on a cleaning frame 24. To the photosensitive drum 21, a driving force is transmitted by an unshown driving motor, so that the photosensitive drum 21 is rotationally driven in the counterclockwise direction in FIG. 2 depending on the image forming operation. Further, on the peripheral surface of the photosensitive drum 21, the charging roller 23 as a primary charging means for electrically charging the surface of the photosensitive drum 21 uniformly and the cleaning blade 28 for removing the developer (toner) remaining on the photosensitive drum (image bearing member) 21 are disposed. The residual toner removed from the surface of the photosensitive drum 21 by the cleaning blade 28 is stored in a residual (waste) toner chamber 30 as an accommodating portion provided at a rear portion of the cleaning frame 24.

[0041] The developing unit 2b is constituted by a developer accommodating portion 70A as an accommodating portion in which the developer (toner) is accommodated, a developing portion 70b where a developing roller 22 as a developer carrying member is rotatably supported, a developing blade unit 73, the developing roller 22, a toner supplying roller 72 and the like. The developer accommodating portion 70A and the developing portion 70B are integrally formed by a developing (device) frame 71 consisting of a plurality of frame members.

[0042] The developing roller 22 is rotated in an arrow Y direction in FIG. 2 in contact with the photosensitive drum 21. Further, on a peripheral surface of the developing roller 22, the toner supplying roller 72 rotated in an arrow Z direction in FIG. 2 in contact with the developing roller 22 and the developing blade unit 73 are disposed. The developing roller 22 and the developing blade unit 73 are mounted on the developing frame 71 via end portion seal members 95a and 95b provided on the developing frame 71 which forms the developing portion 70B and via an under-developing-blade seal (member) 94. As a result, leakage of the toner in the developing portion 70B toward an outside is avoided.

[0043] The developing blade unit 73 as a regulating member includes a developing blade 73b for regulating an amount of the toner on the developing roller 22 and includes a supporting plate 73a for supporting the developing blade 73b, and is mounted on the developing frame 71. Details of the developing blade unit 73 will be described later.

[0044] Inside the developer accommodating portion 70A, a toner stirring mechanism 74 for stirring the accommodated toner and for feeding the toner to the toner supplying roller 72 is provided. Further, the developing unit 2b is urged by an urging spring 29 so that the developing roller 22 contacts the photosensitive drum 21. During the development, the accommodated toner is fed to the toner supplying roller 72 by the toner stirring mechanism 74 rotationally driven in an arrow X direction. As a result, the toner supplying roller 72 rotated in the arrow Z direction supplies the toner to the developing roller 22 by friction with the developing roller 22 rotated in the arrow Y direction. The toner carried on the developing roller (developer carrying member) 22 reaches the developing blade unit 73 with the rotation of the developing roller 22, and the developing blade unit 73 regulates the toner to impart a desired amount of electric charges to the toner, and at the same time, a layer thickness of the toner is regulated. The regulated toner is conveyed to the developing portion, where the photosensitive drum 21 and the developing roller 22 contact each other, with the rotation of the developing roller 22, and then is transferred onto the surface of the photosensitive drum 21 by a DC developing bias applied, at the developing portion, from an unshown power source to the developing roller 22.

[0045] <Seal Structure of Developing Unit>

[0046] Next, with reference to FIGS. 3 to 7, a seal structure of the developing unit 2b in Embodiment 1 will be described.

[0047] FIG. 3 is a schematic sectional view showing a seal structure of a developing unit in this embodiment. FIG. 4 is a schematic front view before a under-developing-blade seal is molded on a developing (device) frame in this embodiment. FIG. 5 is a schematic front view after the under-developing-blade seal is molded on the developing frame in this embodiment. Parts (a) and (b) of FIG. 6 are schematic sectional views of the under-developing-blade seal taken along A-A line indicated in Embodiment 5, wherein (a) of FIG. 6 shows a state before the developing blade unit is connected, and (b) of FIG. 6 shows a state in which the developing blade unit is connected. FIG. 7 is a schematic sectional view showing a seal mold of the under-developing-blade seal in this embodiment.

[0048] As shown in FIG. 3, the developing portion 70B includes a developing opening 71a for permitting supply of the toner, accommodated in the toner accommodating portion 70A as the accommodating portion, to the developing roller 22. Further, the developing roller 22 and the developing blade unit 73 as a regulating member (connected member) for regulating the layer thickness of the toner on the developing roller 22 and disposed in the neighborhood of the developing opening 71a.

[0049] The developing blade unit 73 in this embodiment is constituted by connecting the developing blade 73b, formed with a stainless steel plate or a phosphor bronze plate, with the supporting plate 73a formed of a steel plate. The supporting plate 73a is locked and supported, by screws or the like, at locking portions (FIG. 4) provided at end portions of the developing frame 71. Incidentally, the developing blade 73b may also be prepared by integrally molding a rubber or the like with the supporting plate 73a.

[0050] As shown in FIGS. 3 to 5, at longitudinal end portions of the developing opening 71a, the end portion seal members 95a and 95b for sealing a gap between the developing frame 71 and the peripheral surface of the developing roller 22 are disposed. The end portion seal members 95a and 95b are a flexible member formed with a pile of felt or fibers which are surface-woven, or electrostatically planted fibers, or the like. When the developing roller 22 and the developing blade unit 73 are mounted on the developing frame 71, the peripheral surface of the developing roller 22 and the back surface of the developing blade 73b of the developing blade unit 73 are press-contacted to each other. As a result, in the developing unit 2b, a sealing property of the developing roller 22 with respect to an axial direction is maintained by the end portion seal members 95a and 95b.

[0051] At an upper portion of the developing opening 71a, on the developing frame 71, a seal forming portion 71d is provided between the end portion seal member 95a in a side and the end portion seal member 95b in another side over a longitudinal direction of the developing frame 71. The seal forming portion 71d includes a recessed portion 70d1 into which a resin material as a material for sealing is to be injected, and contact surfaces 71d2 and 71d3 to which a mold is to be contacted. As shown in FIG. 5, the under-developing-blade seal 94 as an elastic member (seal member) is provided at the recessed portion 71d of the seal forming portion 71d of the developing frame 71. The under-developing-blade seal 94 includes a seal function portion 94a as the seal portion and a sprue (gate portion) 94b as an injected resin portion or a molded portion.

[0052] As shown in (a) and (b) of FIG. 6, the sprue 94b is formed, closely to the seal function portion 94a, so as to be projected in a position different from the seal function portion 94a. Further, the seal function portion 94a and the sprue 94b are connected, at lower portions thereof, by a connecting portion 94c. Further, as shown in (b) of FIG. 6, the seal function portion 94a of the under-developing-blade seal 94 is provided in contact with the developing blade unit 73. That is, the seal function portion 94a has a function of maintaining a sealing property so as to prevent the toner from being leaked out from between the developing frame 71 and the developing blade unit 73. Further, as shown in FIG. 5, the under-developing-blade seal 94 is constituted to seal a region between the end portion seal member 95a in the (one) side and the end portion seal member 95b in another side so as to prevent the leakage of the toner while being hermetically contacted to the recessed portion 71d1 with no gap.

[0053] As shown in (b) of FIG. 6, a cross-sectional shape of the seal function portion 94a of the under-developing-blade seal 94 is a projected shape (lip shape) such that a center axis Ox thereof is inclined by an angle α from a seal contact surface 73c of the developing blade unit 73.

[0054] On the other hand, as shown in (b) of FIG. 6, the sprue 94b is provided, more than the seal function portion 94a in an end portion side of the developing blade unit 73 with respect to a direction (widthwise direction) perpendicular to a longitudinal direction. Further, the sprue 94b is provided in a projected state so that an end portion thereof is not compressed by the developing blade unit 73. Specifically, the sprue 94b is formed and projected substantially in the same direction as a direction (arrow direction in (a) of FIG. 6) in which the seal function portion 94a is projected in the projected shape from the developing frame. Further, the sprue 94b has a shape such that the sprue 94b is higher than the seal function portion 94a by a width B1 shown in (a) of FIG. 6 with respect to the direction in which the seal function portion 94a is projected in the projected shape. Further, the sprue 94b is disposed in a side (inside the developing frame 71), more than the seal function portion 94a, in which the toner is accommodated in the developing frame 71, and the sprue 94b is provided closely to the seal function portion 94a.

[0055] As described above, in this embodiment, by forming the sprue 94b so as to be higher than the seal function portion 94a, it becomes possible to dispose the sprue 94b closely to the seal function portion 94a. When the under-developing-blade seal 94 is subjected to the injection molding, as shown in FIG. 7, there is a need to provide a seal mold 83 as the mold with a shape for permitting contact of a gate 82 of a resin material injecting device. Also in such a constitution, there is a need to ensure a thickness y necessary to ensure strength of the seal mold 83. In this embodiment, the height of the resin material injecting port 94b is made higher than the height of the seal function portion 94a, whereby it is possible to ensure the thickness (y in FIG. 7) necessary to ensure the strength of the seal mold 83.

[0056] For comparison, the case where the height of the resin material injecting port 94b of the under-developing-blade seal 94 with respect to the projection direction is set so as to be lower than the seal function portion 94a is shown in FIG. 8. As shown in FIG. 8, in order to ensure the thickness y of the seal mold 83 for ensuring necessary strength of the seal mold 83, it is understood that a distance L2 between the resin material injecting port 94b and the seal function portion 94a is required to be ensured so as to be larger than a distance L1 (FIG. 7). That is, in the case where the height of the resin material injecting port 94b is set so as to be lower than the seal function portion 94a, an increase in size of the under-developing-blade seal 94 is invited.

[0057] Further, in the constitution in this embodiment, the sprue 94b is not provided on the seal function portion 94a, and therefore at a contact portion of the seal function portion 94a with the developing blade unit 73, a stepped portion between the seal function portion 94a and the sprue 94b is not formed, so that the sealing property is maintained with reliability. Further, in a state in which the developing blade unit 73 is mounted on the developing frame 71, as shown in (b) of FIG. 6, the under-developing-blade seal 94 is deformed so as to be flexed in contact with the developing blade unit 73. At this time, also the sprue 94b is deformed so as to be flexed in the same direction by the developing blade unit 73. That is, the sprue 94b is deformed in the same direction as the seal function portion 94a, and therefore the sprue 94b is in a state in which the sprue 94b is not readily contacted to the seal function portion 94a, so that the sealing property (contact state) of the seal function portion 94a is not adversely affected. Further, also the sprue 94b is deformed so as to be flexed, so that a degree of the influence of a repelling force on the developing blade unit 73 is very small when compared with the case of compression deformation. Further, also a degree of an increase in contact force is very small, and therefore there is substantially no influence on the regulation of the layer thickness of the toner on the developing roller 22.

[0058] In this embodiment, the under-developing-blade seal 94 is formed integrally with the developing frame 71 by subjecting an elastic seal material to injection molding on the developing frame 71. In this embodiment, as the material (elastic seal material) for the under-developing-blade seal 94, an elastomer resin material is used. As the elastomer resin material, a styrene-based elastomer resin material which is the same material as the developing frame 71 and which has elasticity may preferably be used since the styrene-based elastomer resin material is excellent in a disassembling operation property of the process cartridge during recycling. This is because when parts of the process cartridge are formed of the same material, there is no need to effect disassembling between the parts. However, even when another elastomer resin material other than the above-described material is used, the elastomer material may only be required to have a similar mechanism characteristic, and it is also possible to use a silicone-based rubber, a soft rubber or the like. Accordingly, in this embodiment, materials including the above-described various elastomer resin materials, rubbers and the like as the elastic seal material are referred collectively as the “elastomer resin material”.

[0059] Here, with reference to FIGS. 9 to 13, a step of molding the under-developing-blade seal 94 in this embodiment will be described. FIG. 9 is a schematic sectional view showing a state in which the seal mold is contacted to the developing frame in this embodiment. FIG. 10 is a schematic sectional view during mold of the under-developing-blade seal on the developing frame in this embodiment. FIG. 11 is a schematic front view during the mold of the under-developing-blade seal on the developing frame in this embodiment. FIG. 12 is a schematic front view of a longitudinal end portion of the developing frame in a state in which the under-developing-blade seal is molded on the developing frame in this embodiment. FIG. 13 is a schematic sectional view showing a state in which the seal mold is retracted from the developing frame in this embodiment.

[0060] First, the end portion seal members 95a and 95b are assembled with the developing frame 71 in longitudinal sides, respectively. Next, as shown in FIG. 9, the seal mold 83 as the mold provided with the seal shape is contacted to the contact surfaces 71d2 and 71d3 of the seal forming portion 71d of the developing frame 71. Then, the gate 82 of the resin material injecting device is contacted to a sprue-forming portion (injecting port) 83b (FIG. 11) provided at a longitudinal central portion of the seal mold 83. The sprue 94b as the molded portion is to be formed correspondingly to a shape of the sprue-forming portion 83b. Here, the resin material injecting port 94b of the under-developing-blade seal 94 has the shape such that the resin material injecting port 94b is projected so as to be higher than the seal function portion 94a. For that reason, it is possible to ensure a space in which the gate 82 of the resin material injecting device enters and contacts the seal mold 83 without communicating with a seal function portion-forming portion 83a, of the seal mold 83, where the seal function portion 94a is to be formed.

[0061] Next, as shown in FIG. 10, the gate 82 of the resin material injecting device is contacted to the seal mold 83, and then the elastomer resin material as the seal material for the under-developing-blade seal 94 is injected from the gate 82 of the resin material injecting device into the sprue-forming portion 83b. The elastomer resin material flows from the sprue-forming portion 83b toward the seal function portion-forming portion 83a of the seal mold 83.

[0062] Then, the injected elastomer resin material flows, as shown in FIG. 11, toward each of the longitudinal end sides in a space formed by the recessed portion 71d1 of the seal forming portion 71d and the seal function portion-forming portion 83a of the seal mold 83. The elastomer resin material flowed in the longitudinal direction reaches, as shown in FIG. 12, the end portion seal member 95a (95b) provided at the longitudinal end portion, and is sufficiently connected (contacted) to the end portion seal member 95a (95b) with no gap.

[0063] Then, after the injection of the elastomer resin material is ended, the developing frame 71 and the seal mold 83 are retracted from the gate 82. Next, the seal mold 83 is retracted from the developing frame 71. As shown in FIG. 13, when the seal mold 83 is retracted from the developing frame 71, on the developing frame 71, the seal function portion-forming portion 83a and the sprue 94b of the under-developing-blade seal 94 are formed. The sprue 94b is formed in the shape such that the sprue 94b is projected so as to be higher than the seal function portion 94a. When the seal mold 83 is retracted from the developing frame 71, a close contact force acting on between the under-developing-blade seal 94 and surfaces 71h and 71j which form the recessed portion 71d1 of the seal forming portion 71d generates reaction in a shearing direction with respect to the retraction direction of the seal mold 83. For that reason, the under-developing-blade seal 94 remains in the developing frame 71 side and is not moved toward the seal mold 83 side while being adhered to the seal mold 83, so that a state in which the under-developing-blade seal 94 is formed with reliably at the seal forming portion 71d of the developing frame 71 is created.

[0064] As described above, in this embodiment, by employing the constitution in which the sprue 94b is projected in the projection direction in a degree larger than that of the seal function portion 94a, it is possible to improve the sealing property while suppressing the increase in size of the under-developing-blade seal 94. Further, the sprue 94b is provided in the position different from the position of the seal function portion 94a, so that it is possible to maintain the sealing property without forming an uneven portion at the seal function portion 94a.

[0065] Next, Embodiment 2 will be described with reference to FIGS. 14 to 16. FIG. 14 is a schematic sectional view of a seal structure of a developing frame in this embodiment. FIG. 15 is a schematic perspective view of the seal structure of the developing frame in this embodiment. Parts (a) and (b) of FIG. 16 are schematic sectional views of a frame seal portion of the developing frame in this embodiment, wherein (a) shows a state before a developing frame member is connected, and (b) shows a state in which the developing frame member is connected. In this embodiment, a frame seal 96 as a seal member for sealing between developing frame members 78 and 79 each being a part of the developing frame 71 is formed of the elastomer resin material.

[0066] As shown in FIGS. 14 and 15, the frame seal 96 includes a seal function portion 96a as the seal portion and a sprue 96b as the molded portion. The seal function portion 96a is formed at a seal forming portion 78a of the developing frame member 78 by injection molding, and is projected in a projected shape from the seal forming portion 78a. Further, the seal function portion 96a has a planar shape at the surface thereof. The sprue 96b is formed so as to be projected in a position different from a position of the seal function portion 96a and is connected to the seal function portion 96a.

[0067] Further, as shown in FIG. 15 and (a) of FIG. 16, the sprue 96b is formed and projected in the same direction as a direction (arrow direction in (a) of FIG. 16) in which the seal function portion 96a is projected in the projected shape from the seal forming portion 78a of the developing frame member 78. Further, in this embodiment, the sprue 96b is formed so as to be higher than the seal function portion 96a by a height B2 shown in (a) of FIG. 16 with respect to the projection direction.

[0068] Here, in this embodiment, the developing frame member 79 as a connected member includes a projected portion 79a as a projection projected so as to compress the seal function portion 96a between the projected portion 79a and the developing frame member 78. The projected portion 79a is disposed opposed to the seal function portion 96a of the frame seal 96 formed on the developing frame member 78. Then, in connection between the developing frame members 78 and 79, as shown in (b) of FIG. 16, the projected portion 79a of the developing frame member 79 contacts the seal function portion 96a of the frame seal 96. As a result, a sealing property between the developing frame members 78 and 79 is maintained.

[0069] Further, at a portion where the seal function portion 96a contacts the developing frame member 79, a stepped portion between the seal function portion 96a and the sprue 96b is not formed, and therefore the sealing property is maintained. Further, between the developing frame members 78 and 79 which are molded by using the resin material, it is easy to form a shape such that the sprue 96b does not contact the developing frame member 79. For that reason, even when the seal function portion 96a has a planar shape, it is possible to provide a constitution in which a repelling force of the frame seal 96 generated by contact with the projected portion 79a of the developing frame member 79 does not readily influence on the developing frame member 79.

[0070] Even when a constitution in which the surface of the seal function portion 96a is flush with the surface of the sprue 96b is employed, the frame seal 96 is in contact with the projected portion 79b of the developing frame member 79 in a state the projected portion 79b bites into the seal function portion 96a, and therefore the sealing property is not impaired due to the influence of deformation of the sprue 96b on deformation of the seal function portion 96a. Further, a seal molding step is similarly performed as described above, and therefore the frame seal 96 is formed on the developing frame member 78 with reliability.

[0071] Next, Embodiment 3 will be described. In Embodiment 1, the under-developing-blade seal 94 of the developing unit 2b shown in FIG. 2 was described, but the present invention is also applicable to a under-cleaning-blade seal 25 of the photosensitive drum unit (cleaning unit) 2a. That is, the under-cleaning-blade seal 25 as a seal member provided between the cleaning frame 24 and a cleaning blade 28 as a connected member connected with the cleaning frame 24 has the following constitution.

[0072] The under-cleaning-blade seal 25 is formed by bringing a mold into contact with the cleaning frame 24 and then by injecting the resin material onto the mold. The under-cleaning-blade seal 25 includes a seal function portion as a seal portion and a sprue as a molded portion. By providing such a under-cleaning-blade seal 25, it is possible to prevent the toner from leaking out from between the cleaning frame 24 and the cleaning blade 28.

[0073] In the process cartridge 2 including the under-cleaning-blade seal 25 in this embodiment, an effect similar to the effect in Embodiment 1 can be obtained. That is, in this embodiment, by employing a constitution in which the sprue of the under-cleaning-blade seal 25 is projected in the projection direction in a degree larger than that of the seal function portion, it is possible to improve the sealing property while suppressing an increase in size of the under-cleaning-blade seal 25. Further, the sprue is provided in a position different from a position of the seal function portion, and therefore an uneven portion is not formed on the seal function portion, so that it is possible to maintain the sealing property.

[0074] Incidentally, the constitution in the above-described embodiments can be employed in a combined manner to the possible extent.

[0075] According to the present invention, it is possible to improve the sealing property while suppressing the increase in size of the seal member.

[0076] While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purpose of the improvements or the scope of the following claims.

[0077] This application claims priority from Japanese Patent Application No. 219773/2012 filed Oct. 1, 2012, which is hereby incorporated by reference.