Process cartridge and disassembling method of the process cartridge

[0001] The present invention relates to a process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer.

[0002] Here, the electrophotographic image forming apparatus forms an image on a recording sheet by using an electrophotographic image forming method and, e.g., includes the electrophotographic copying machine, the electrophotographic printer (such as a laser beam printer or an LED printer), a facsimile machine, a word processor, and the like.

[0003] Further, the process cartridge is prepared by integrally assembling an electrophotographic photosensitive drum at least one of a charging means, a developing means and a cleaning means into a cartridge, which is detachably mountable to the main assembly of the image forming apparatus.

[0004] In a conventional image forming apparatus using an electrophotographic image forming process, the process cartridge prepared by integrally assembling the electrophotographic photosensitive drum and a process means acting on the electrophotographic photosensitive drum into a cartridge is present. A process cartridge type in which this process cartridge is detachably mountable to the main assembly of the electrophotographic image forming apparatus has been widely employed.

[0005] According to this process cartridge type, maintenance of the electrophotographic image forming apparatus can be performed by a user himself (herself) without relying on a service person, so that operativity is considerably improved.

[0006] Further, e.g., some process cartridges include a cleaning unit (first frame) for holding the electrophotographic photosensitive drum and a developing unit (second frame) for holding the developing means for developing an electrophotographic, formed on the electrophotographic photosensitive drum, with toner (developer). These first and second frames are rotatably connected to each other by a round bar-like connecting pin.

[0007] Incidentally, the electrophotographic image forming apparatus forms the image on the sheet with the toner. When the image formation on the sheet is repeated, in the process cartridge including the developing means, the toner accommodated in a developer accommodating portion is gradually consumed. Then, at some feature time, the developer is consumed to the extent that the image of satisfactory quality to the user cannot be formed, so that a commercial value as the process cartridge is lost. With respect to disassembling, cleaning and reuse (recycle) by collecting the spent process cartridge as described above, an invention described in Japanese Patent No. 3320403 is disclosed as n example of a method therefore, and an invention described in Japanese Laid-Open Patent Application (JP-A) 2001-42753 is disclosed as an example of a constitution thereof.

[0008] The invention described in Japanese Patent No. 3320403 relates to a disassembling method of a process cartridge in which a first frame for supporting the electrophotographic photosensitive drum and a second frame for supporting a developing roller are rotatably and movably connected to each other and in which a separation step of separating the first frame and the second frame is included. According to this method, the spend process cartridge is collected and then can be disassembled, cleaned and reused.

[0009] Further, the invention described in JP-A 2001-42753 relates to the constitution of a process cartridge in which the first frame for supporting the electrophotographic photosensitive drum and the second frame for supporting the developing roller are rotatably and movably connected to each other by a connecting pin. Further, in this process cartridge, when the connecting pin for connecting the first frame and the second frame is pulled out, the first frame and the second developing roller are configured to be separated. Particularly, the connecting pin is configured to be liable to be easily pulled out. According to this constitution, when a specialized tool is used, the spent process cartridge can be easily disassembled.

[0010] However, as described in the above-mentioned documents, a technique for separating the first frame and the second developing roller from each other was merely present in the conventional art and there was no constitution and method in which other members (to be assembled into the first frame or the second frame) were separated simultaneously. Therefore, such other members have no choice but to be individually separated.

[0011] In view of the above circumstances, a principal object of the present invention is to provide a process cartridge capable of separating other members assembled to a first frame and a second frame at the same time during separation of the first frame and the second developing roller and is to provide a disassembling method of the process cartridge.

[0012] According to an aspect of the present invention, there is provided a process cartridge detachably mountable to a main assembly of an image forming apparatus, the process cartridge comprising:

[0013] an image-bearing member on which an electrostatic image is to be formed;

[0014] a first frame;

[0015] a bearing member, detachably mountable to the first frame, for rotatably supporting the image-bearing member;

[0016] a first hole provided in the bearing member;

[0017] a first wall, provided on the first frame, in which a second hole is provided;

[0018] a second frame for rotatably supporting a developer carrying member on which a developer for developing the electrostatic image is to be carried;

[0019] a second wall, provided on the second frame, in which a third hole is provided; and

[0020] a connecting member including a shaft portion penetrating through the first hole, the second hole and the third hole and tightly engaging in the second hole, and including a flange portion, provided at an end portion of the shaft portion, for preventing the bearing member from being detached from the first frame.

[0021] 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.

[0028] Hereinbelow, preferred embodiments of the present invention will be described specifically in an exemplary manner with reference to the drawings. However, dimensions, materials, shapes, relative positions of constituent elements described in the following embodiments are appropriately changed depending on constitutions and various conditions of devices (apparatuses) to which the present invention is applied and therefore the scope of the present invention is not limited to those described in the following embodiments, unless otherwise specified.

[0029] FIG. 1 is a sectional view showing a structure of an image forming apparatus 100 in Embodiment 1 of the present invention. The image forming apparatus 100 utilizes an electrophotographic image forming process. As shown in FIG. 1, the image forming apparatus 100 includes an image forming apparatus main assembly 100A (hereinafter referred to as an apparatus main assembly). Inside the apparatus main assembly 100A, an image forming portion for forming an image is provided. The image forming portion includes photosensitive drums 1a, 1b, 1c and 1d which are an “image bearing member” and an “electrophotographic photosensitive drum” and includes primary transfer rollers 12a, 12b, 12c and 12d, and the like. At least the photosensitive drums 1a, 1b, 1c and 1d are included in process cartridges 7a, 7b, 7c and 7d, respectively, and the process cartridges 7a, 7b, 7c and 7d are assembled in a detachably mountable manner into the apparatus main assembly 100A.

[0030] The image forming apparatus 100 includes four mounting portions (not shown) which are cartridge mounting means obliquely juxtaposed with respect to a horizontal direction. The mounted process cartridges 7a to 7d include the photosensitive drums 1a to 1d, respectively. The (electrophotographic) photosensitive drums 1a to 1d are rotationally driven in the counterclockwise direction in FIG. 1 by a driving member (not shown). Around the photosensitive drums 1a to 1d, the following process means are successively disposed along the rotational direction of the photosensitive drums 1a to 1d. That is, cleaning members 6a to 6d for removing a developer (toner) remaining on the surfaces of the photosensitive drums 1a to 1d after transfer and charging rollers 2a to 2d for uniformly charging the surfaces of the photosensitive drums 1a to 1d are disposed. Further, developing units 4a to 4d for developing an electrostatic image with the toner are disposed. Further, a scanner unit 3 for forming the electrostatic image on the photosensitive drums 1a to 1d and an intermediary transfer belt 5 onto which four color toner images on the surfaces of the photosensitive drum 1a to 1d are collectively transferred are disposed. The photosensitive drums 1a to 1d, the cleaning members 6a to 6d, the charging rollers 2a to 2d and the developing units 4a to 4d are integrally assembled into cartridges color by color to constitute the process cartridges 7a to 7d, respectively. These process cartridges 7a to 7d are dismountable from and mountable into the apparatus main assembly 100A of the image forming apparatus 100 by a user.

[0031] The intermediary transfer belt 5 is stretched by a driving roller 10, a tension roller 11 and a stretching roller 21. Further, inside the intermediary transfer belt 5, the primary transfer rollers 12a to 12d are disposed opposed to the photosensitive drums 1a to 1d, respectively. Further, a transfer bias is applied to the intermediary transfer belt 5 by a bias applying means (not shown).

[0032] The toner images formed on the surfaces of the photosensitive drums 1a to 1d are successively primary-transferred onto the surface of the intermediary transfer belt 5 by rotating each of the photosensitive drums 1a to 1d in a direction indicated by an arrow Q, rotating the intermediary transfer belt 5 in a direction indicated by an arrow R, and by applying a bias of a positive polarity to the primary transfer roller 12. Then, the four color toner images are conveyed to a secondary transfer portion 15 in a state in which they are superposed on the intermediary transfer belt 5.

[0033] In synchronism with an image forming operation, a sheet S which is a recording medium is conveyed by a conveying means consisting of a sheet feeding device 13, a registration roller pair 17, and the like. The sheet feeding device 13 includes a sheet feeding (accommodating) cassette 24 for accommodating the sheets S, a sheet feeding roller 8 for feeding the sheet S, and a conveying roller pair 16 for conveying the fed sheet S. The sheet feeding cassette 24 can be pulled out in a frontward direction of the apparatus main assembly 100A. The sheets S stacked in the sheet feeding cassette 24 is pressed by the sheet feeding roller 8 and is separated one by one by a separation pad 9 (scraper separation type) and then is conveyed.

[0034] The sheet fed from the sheet feeding device 13 is conveyed to the secondary transfer portion 15 by the registration roller pair 17. At the secondary transfer portion 15, the bias of the positive polarity is applied to a secondary transfer roller 18. As a result, onto the conveyed sheet S, the four color toner images on the intermediary transfer belt 5 are secondary-transferred.

[0035] A fixing portion 14 which is a fixing means fixes the toner images formed on the sheet 5 by applying heat and pressure to the toner images. A fixing belt 14a has a cylindrical shape and is guided by a belt guide member (not shown) to which a heating means such as a heater is bonded. Further, the fixing belt 14a and a pressing roller 14b form a fixing nip with a predetermined press-contact force.

[0036] Then, the sheet S which is conveyed from the image forming portion and on which unfixed toner images are formed is heated and pressed in the fixing nip between the fixing belt 14a and the pressing roller 14b. Thus, the unfixed toner images on the sheet S are fixed on the sheet S. Thereafter, the sheet S on which the toner images are fixed is discharged onto a sheet discharging tray 20 by a sheet discharging roller pair 19.

[0037] Further, the toner remaining on the intermediary transfer belt 5 after the secondary transfer of the toner images onto the sheet S is removed by a transfer belt cleaning device 23. The removed toner passes through a residual toner conveying path (not shown) and is collected in a residual toner collecting container (not shown) disposed at a rear surface portion of the image forming apparatus.

[0038] FIG. 2 is a sectional view showing a structure of the process cartridge 7a. Each of the process cartridges 7a to 7d contains toner t. The process cartridge 7a containing yellow toner t, the process cartridge 7b containing magenta toner t, the process cartridge 7c containing cyan toner t and the process cartridge 7d containing black toner have the same constitution. For that reason, only the constitution of the process cartridge 7a will be described, and the description may also be quoted as that for the constitutions of the process cartridges 7b, 7c and 7d.

[0039] The process cartridge 7a is divided into a cleaning unit 26a including the photosensitive drum 1a, the charging roller 2a which is charging means, and the cleaning member 6a which is a cleaning means, and the developing unit 4a including a developing roller 25a which is a developing means.

[0040] The cleaning unit 26a includes a cleaning frame 27 (first frame). To the cleaning frame 27, the photosensitive drum 1a is rotatably attached through drum bearings 29 and 59 (FIG. 3(a)) described later. Further, a driving force of a driving motor (not shown) is transmitted to the cleaning unit 26a, so that the photosensitive drum 1a is rotationally driven in accordance with the image forming operation. On the peripheral surface of the photosensitive drum 1a, as described above, the charging roller 2a and the cleaning member 6a are disposed. The residual toner removed from the surface of the photosensitive drum 1a by the cleaning member 6a drops into a removed toner container 27a. To the cleaning frame 27, a charging roller bearing 28 is attached movably in a direction indicated by an arrow D passing through the center of the charging roller 2a and the center of the photosensitive drum 1a. A shaft (axis) 2j of the charging roller 2a is rotatably attached to the charging roller bearing 28. Further, the charging roller bearing 28 is pressed toward the photosensitive drum 1a by a charging roller pressing member 46.

[0041] The developing unit 4a includes the developing roller 25a rotating in a direction indicated by an arrow B in contact with the photosensitive drum 1a and includes a developing device frame 31. The developing device frame 31 which is a second frame supports the developing roller 25a which is a developer carrying member for carrying the electrophotographic formed on the surface of the photosensitive drum 1a. The developing roller 25a is rotatably supported by the developing device frame 31. Further, on the peripheral surface of the developing roller 25a, a toner feeding roller 34a rotating in a direction indicated by an arrow C in contact with the developing roller 25a and a developing blade 35 for regulating a toner layer on the developing roller 25a are disposed. Further, in a toner accommodating portion 31a of the developing device frame 31, a toner feeding (conveying) member 36 for stirring the accommodated toner and feeding the toner to the toner feeding roller 34 is provided.

[0042] Further, the developing unit 4a and the cleaning unit 26a are swingably connected by a connecting pin 37, described later, which is a connecting member. The developing unit 4a is urged by an urging (pressing) spring 38. For that reason, during the image formation by the process cartridge 7a, the developing unit 4a is rotated about the connecting pin 37 in a direction indicated by an arrow A< so that the developing roller 25a contacts the photosensitive drum 1a.

[0043] FIG. 3(a) is a perspective view of the cleaning unit 26a which is disassembled and as seen from a driving side of the cleaning unit 26a. FIG. 3(b) is a perspective view of the cleaning unit 26a which is disassembled and as seen from a non-driving side of the cleaning unit 26a. With reference to these FIGS. 3(a) and 3(b), the constitution in which the photosensitive drum 1a and the drum bearings 29 and 59 which constitute the cleaning unit 26a are assembled to the cleaning frame 27 will be described in detail.

[0044] The photosensitive drum 1a is provided with a drum flange 41 at one end portion thereof and is provided with a drum flange 42 at the other end portion thereof. At an end surface of the drum flange 41 on the driving side of the cleaning unit 26a, a projected portion 41a which is a cartridge-side coupling means is formed.

[0045] The drum bearing 29 which is a bearing member includes an inner peripheral portion 29b which is a bearing hole in which the photosensitive drum 1a is rotatably supported and includes a through-hole 29d which is a first pin hole (first hole portion). The drum bearing 29 will be described more specifically. The drum bearing 29 includes an outer peripheral projected portion 29b projected toward the cleaning frame 27 and includes a plate portion 29k. The drum bearing 29 includes the inner peripheral portion 29b which penetrates through the outer peripheral projected portion 29a in an axial direction of the photosensitive drum 1a. Further, the drum bearing 29 includes a positioning hole 29c, provided in the plate portion 29k, for positioning the drum bearing 29 relative to the cleaning frame 27. Further, the drum bearing 29 includes the through-hole 29d, provided in the plate portion 29k, into which the connecting pin 37 described later is inserted.

[0046] Similarly, the drum bearing 59 which is a bearing member includes an inner peripheral portion 59b which is the bearing hole in which the photosensitive drum 1a is rotatably supported and includes a through-hole 59d which is the first pin hole. The drum bearing 59 will be described more specifically. The drum bearing 59 includes an outer peripheral projected portion 59b projected toward the cleaning frame 27 and includes a plate portion 59k. The drum bearing 59 includes the inner peripheral portion 59b which penetrates through the outer peripheral projected portion 59a in an axial direction of the photosensitive drum 1a. Further, the drum bearing 59 includes a positioning hole 59c, provided in the plate portion 59k, for positioning the drum bearing 59 relative to the cleaning frame 27. Further, the drum bearing 59 includes the through-hole 59d, provided in the plate portion 59k, into which the connecting pin 37 described later is inserted.

[0047] The cleaning frame 27 includes an outer wall 27b, extending in a direction perpendicular to an axis of the photosensitive drum 1a, on one end portion side of the photosensitive drum 1a with respect to the axial direction of the photosensitive drum 1a. This outer wall 27b is provided with a mounting hole 27c for receiving the outer peripheral projected portion 29a in the case where the outer peripheral projected portion 29a of the drum bearing 29 is inserted into the mounting hole 27c.

[0048] Further, The cleaning frame 27 includes an outer wall 57b, extending in a direction perpendicular to an axis of the photosensitive drum 1a, on the other end portion side of the photosensitive drum 1a with respect to the axial direction of the photosensitive drum 1a. This outer wall 57b is provided with a mounting hole 57c for receiving the outer peripheral projected portion 59a in the case where the outer peripheral projected portion 59a of the drum bearing 59 is inserted into the mounting hole 57c.

[0049] Each of these mounting holes 27c and 57c defines a partly circular portion having an opposite distance, between ends of the partly circular portion, which is smaller than a diameter of the mounting holes 27c and 57c and is larger than the diameter of the drum flanges 41 and 42. The drum flanges 41 and 42 engage in the inner peripheral portions 29b and 59b of the drum bearings 29 and 59. Positioning pins 27d and 57d formed integrally with and provided on the outer walls 27b and 57b of the cleaning frame 27 are configured to hermetically engage in the positioning holes 29c and 59c provided in the drum bearings 29 and 59. Further, longitudinal positions of the drum bearings 29 and 59 and the cleaning frame 27 are determined by the outer walls 27b and 57b.

[0050] In the above-described manner, the photosensitive drum 1a assembled into a unit is mountable to the cleaning frame 27 from a direction perpendicular to the axial direction (longitudinal direction) of the photosensitive drum 1a. At the same time, when the drum bearings 29 and 59 are mounted to the cleaning frame 27 from the longitudinal direction, the positions of the drum bearings 29 and 59 relative to the cleaning frame 27 are determined. In order to mount the photosensitive drum 1a to the cleaning frame 27, the photosensitive drum 1a is moved in the direction perpendicular to its longitudinal direction and then the drum flanges 41 and 42 are passed through the ends of the partly circular portions and are inserted into the bearing mounting holes 27c and 57c. In this state, the drum bearings 29 and 59 are moved in the axial direction, so that the drum flanges 41 and 42 are engaged in the inner peripheral portions 29b and 59b. By further moving the drum flanges 41 and 42 in the axial direction, the outer peripheral projected portions 29a and 59a are engaged in the bearing mounting holes 27c and 57c of the cleaning frame 27 and then the drum bearings 29 and 59 are fastened with screws X and X.

[0051] FIG. 4(a) is an enlarged exploded perspective view of the process cartridge 7a in a state in which the cleaning unit 26a and the developing unit 4a are separated. FIG. 4(b) is an enlarged sectional view of the process cartridge 7a in a state in which the cleaning unit 26a and the developing unit 4a are connected by the connecting pin 37. Incidentally, in Embodiment 1, the connection between the cleaning unit 26a and the developing unit 4a will be described with respect to only one longitudinal side of the process cartridge 7a but the same connecting constitution is employed also with respect to the other longitudinal side of the process cartridge 7a.

[0052] The cleaning frame 27 which is a first frame includes the outer wall 27b which is a plate-like outside plate (first wall portion) formed on an outer end portion side with respect to the axial direction of the photosensitive drum 1a. Further, the cleaning frame 27 includes an inner wall 27e which is a plate-like side plate (third wall portion) formed on an inner end portion side with respect to the axial direction of the photosensitive drum 1a. The outer wall 27b is provided with a connecting hole 42a which is a second pin hole (second hole portion). The inner wall 27e is provided with a connecting hole 42b which is a third pin hole (third hole portion). The drum bearing 29 is mountable to the cleaning frame 27 by the connecting pin 37 although it will be described later. Further, the drum bearing 29 is provided with a through-hole 29d which is formed at a position coaxial with the connecting holes 42a and 42b provided in the cleaning frame 27 and is larger in diameter than those of the connecting holes 42a and 42b.

[0053] On the other hand, the developing unit 4a is provided with an arm portion (second wall portion) 48 formed on an end portion side with respect to the axial direction of the photosensitive drum 1a and is projected in a direction perpendicular to the axial direction of the photosensitive drum 1a. On an end side of the arm portion 48, a connecting hole 48a which is a fourth pin hole (third hole portion) is provided.

[0054] The connecting pin 37 includes a shaft portion 37a which is engaged in the through-hole 29d, the connecting hole 42a, the connecting hole 42b and the connecting hole 48a so as to swingably connect the cleaning frame 27 and the developing device frame 31 with each other, and includes a flange portion 37b provided at an end portion of the shaft portion 37a. Specifically, the connecting pin 37 is inserted into the through-hole 29d of the drum bearing 29, the connecting hole 42a of the outer wall 27b, the connecting hole 42b of the inner wall 27e and the connecting hole 38a of the arm portion 48. Then, the frames 27 and 31 are retained by the flange portion 37b having a larger diameter than those of the through-hole 29d and the connecting hole 37a. In a state in which the connecting pin 37 is inserted into the connecting holes 42a, 42b and 48a, these connecting holes 42a, 42b and 48a are swingable each other. Further, diameter dimensions of the respective connecting holes 42a, 42b and 48a and the shaft portion 37a are set so that the shaft portion 37a of the connecting pin 37 insures press fit (tight engagement) with respect to the connecting holes 42a and 42b of the cleaning frame 27 and so that the shaft portion 37a insures clearance (loose) fit with respect to the connecting hole 49a of the developing unit 4a.

[0055] In the case where the cleaning unit 4a and the cleaning unit 26a are connected by the connecting pin 37, the developing unit 4a and the cleaning unit 26a are assembled at a position in which the connecting holes 42a, 42b and 48a are aligned with each other in the axial direction of the photosensitive drum 1a.

[0056] In that state, the shaft portion 37a of the connecting pin 37 penetrates through the through-hole 29d of the drum bearing 29, the connecting holes 42a and 42b of the cleaning frame 27 and the connecting hole 48a of the developing unit 4a, so that the developing unit 4a and the cleaning unit 26a are connected (FIG. 4(b)). The connecting pin 37 is positioned with respect to its longitudinal direction by abutment of an abutment surface 37c of the flange portion 37b against an abutment bearing surface 29f of the drum bearing 29. Therefore, the connecting pin 37 is held by the cleaning unit 26a by sandwiching the drum bearing 29 between the flange portion 37b and the cleaning unit 26a, so that the developing unit 4a is rotatably supported by the cleaning unit 26a. Thus, the drum bearing 29 is fixable on the cleaning frame 27 by the flange portion 37b. Further, in a state in which the flange portion 37b and the outer wall 27b sandwiched the drum bearing 29 therebetween, the drum bearing 29 is mounted on the outer wall 27b.

[0057] Further, the developing unit 4a is provided with a projection 39 for spring, and an urging spring (compression coil spring) 38 is externally inserted into the projection 39. When the developing unit 4a and the cleaning unit 26a are connected, the urging spring 38 is configured to be positioned between the projection 39 of the developing unit 4a and a spring bearing surface 27f of the cleaning unit 26a. As a result, the photosensitive drum 1a of the cleaning unit 26a and the developing roller (not shown) of the developing unit 4a contact each other with a predetermined pressure.

[0058] FIG. 5 is a perspective view of the process cartridge 7a. A disassembling method of the process cartridge 7a will be specifically described below with reference to FIG. 5 in combination with FIG. 4(b). Particularly, the disassembling method of the process cartridge 7a is characterized in that when the connecting pin 37 is disengaged, the drum bearing 29 is detachable from the cleaning frame 27 and at the same time, the cleaning frame 27 is detachable from the developing device frame 31. First, the screw X which secures the drum bearing 29 and the cleaning frame 27 is disconnected. In a state in which the screw X is disconnected, the drum bearing 29 is fixed on the cleaning frame 27 by the flange portion 37b of the connecting pin 37. Then, a simple tool such as a screwdriver F is inserted into a recessed portion 43 provided in the neighborhood of the connecting hole 42a of the cleaning frame 27. When the screwdriver F is rotated in a direction indicated by an arrow J while utilizing the principle of leverage, the drum bearing 29 is detached from the cleaning frame 27. Further, when the drum bearing 29 is detached from the cleaning frame 27, the flange portion 37b of the connecting pin 37 receives a force from an abutment surface 29e of the drum bearing 29 in an opposite direction to the insertion direction. Therefore, the connecting pin 37 is disconnected integrally with the drum bearing 29 from the cleaning frame 27.

[0059] When the connecting pin 37 is disconnected, the cleaning unit 26a and the developing unit 4a are disassembled. Further, with respect to the cleaning unit 26a, the photosensitive drum 1a is dismounted by detaching the drum bearing 29 from the cleaning unit 26a.

[0060] As described above, according to Embodiment 1, the connecting pin 37 for connecting the cleaning unit 26a and the developing unit 4a includes the shaft portion 37a and the flange portion 37b, and the flange portion 37b sandwiches the drum bearing between itself and the outer wall 27b and the shaft portion 37a fixes the drum bearing 29 on the cleaning frame 27. As a result, the connecting pin 37 can be used as one of fixing means for fixing the drum bearing 29 on the cleaning frame 27, so that reduction in the number of screws can be realized. Further, during the disassembling, by dismounting the drum bearing from the cleaning frame 27, the connecting pin 37 can also be disconnected at the same time, so that a disassembling step of the cleaning unit 26a and the developing unit 4a and a disassembling step of the photosensitive drum 1a can be performed simultaneously. Further, according to Claim 1, the members such as the connecting pin 37 and the drum bearings 29 and 59 can be dismounted without being damaged.

[0061] In this embodiment, the constitution in which the shaft portion 37a of the connecting pin 37 is engaged in both of the second hole portion 42a and the fourth hole portion 42b is described but the present invention is not limited to this constitution. For example, a constitution in which the shaft portion 37a is not engaged in the fourth hole portion 42b may also be employed. In this case, the shaft portion 37a is configured to be engaged in the first hole portion 29d, the second hole portion 42a and the third hole portion 48a.

[0062] FIG. 6(a) is a perspective view showing a structure of a cleaning unit 260a provided in an image forming apparatus in Embodiment 2. FIG. 6(b) is a perspective view showing a structure of a process cartridge 70a provided in the image forming apparatus in Embodiment 2. With respect to constitutions of the cleaning unit 260a and the process cartridge 70a in this embodiment, the same constitutions as the cleaning unit 26a and the process cartridge 7a in Embodiment 1 and their effects will be described by using the same reference numerals or symbols and will be appropriately omitted from the description. Also in Embodiment 2, the present invention is applied to the image forming apparatus similar to that in Embodiment 1, so that the image forming apparatus will be omitted from the description. A difference of the cleaning unit 260a and the process cartridge 70a in Embodiment 2 from the cleaning unit 26a and the process cartridge 7a in Embodiment 1 is that the connecting pin 37 is fixed by welding on a drum bearing 290 in the cleaning unit 260a.

[0063] As shown in FIG. 6(a), the cleaning unit 260a includes, in place of the drum bearing 29, the drum bearing 290 on which a welding rib 291 and a grip portion 292 are formed. Here, the welding rib 291 has a circular shape and is configured to have a diameter larger than that of the flange portion 37b of the connecting pin 37.

[0064] The cleaning unit 260a and the developing unit 4a are connected by the connecting pin 37 by the same method as in Embodiment 1 and thereafter the welding rib 291 provided on the drum bearing 290 is welded so as to cover the flange portion 37b of the connecting pin 37 with a resin (FIG. 6(b)). Thus, by fixing the connecting pin 37 in the drum bearing 290 by the welding, the connecting pin 37 can be prevented from being detached by an impact or the like.

[0065] Further, when the cleaning unit 260a and the developing unit 4a are disassembled, the screw X which secures the drum bearing 290 and the cleaning frame 27 is disconnected. Thereafter, the grip portion 292 of the drum bearing 290 is gripped and pulled in a direction indicated by an arrow H in FIG. 6(b), the drum bearing 290 can be detached from the cleaning frame 27. Further, by the drum bearing 290, the connecting pin 37 can also be disconnected from the cleaning frame 270.

[0066] By disconnecting the connecting pin 37, the cleaning unit 260a and the developing unit 4a can be disassembled. Further, with respect to the cleaning unit 260a, the photosensitive drum 1a can be dismounted by detaching the drum bearing 290. Incidentally, in this embodiment, only the cleaning unit 260a for yellow and the process cartridge 70a for yellow are described but the same constitutions can also be employed with respect to the cleaning units and developing units for magenta, cyan and black.

[0067] According to the image forming apparatuses in Embodiment 1 and Embodiment 2, when the connecting pin 37 is disconnected, the cleaning frame 27 and the developing device frame 31 are separated and at the same time, the drum bearing 29 (290) for supporting the photosensitive drum 1a is separated from the cleaning frame 27. As a result, the process cartridge 7a (70a) can be easily disassembled compared with the conventional process cartridge.

[0068] 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.

[0069] This application claims priority from Japanese Patent Application No. 281597/2009 filed Dec. 11, 2009, which is hereby incorporated by reference.