Photosensitive unit, cartridge, electrophotographic image forming apparatus

Abstract

To develop a photoreceptor unit.SOLUTION: A photoreceptor unit is removably attached to an apparatus main body of an image forming apparatus having a first main body-side helical gear part and a second main body-side helical gear part that rotate coaxially, and has: a photoreceptor that is rotatable around an axis of rotation; a first unit-side helical gear part for meshing with the first main body-side helical gear part; and a second unit-side helical gear part for meshing with the second main body-side helical gear part. The twist direction of the teeth of the second unit-side helical gear part is the same as the twist direction of the teeth of the first unit-side helical gear part. The twist angle of the teeth of the second unit-side helical gear part is larger than the twist angle of the teeth of the first unit-side helical gear part. In the photoreceptor unit, in a state in which the first unit-side helical gear part is meshed with the first main body-side helical gear part and the second unit-side helical gear part is meshed with the second main body-side helical gear part, the first unit-side helical gear part and the second unit-side helical gear part rotate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] An electrophotographic image forming apparatus is an apparatus that forms an image on a recording medium using an electrophotographic image forming method. Examples of electrophotographic image forming apparatuses include electrophotographic copying machines, electrophotographic printers (LED printers, laser beam printers, etc.), facsimile machines, and word processors. [Background technology]

[0003] In an electrophotographic image forming apparatus (hereinafter also simply referred to as an "image forming apparatus"), a toner image is formed on an electrophotographic photosensitive member (photosensitive drum or drum), and the toner image is then transferred directly or indirectly to a recording medium, thereby forming an image on the recording material.

[0004] Generally, such image forming devices require the replenishment of toner (developer), maintenance of various components, etc. Therefore, there are cartridge-type image forming devices that are configured so that cartridges can be detachably attached to the image forming device, and by replacing the cartridges, toner replenishment, maintenance, etc. can be performed.

[0005] A cartridge is a device that has at least one of a drum or a process means and is removably mounted in the main body of an image forming apparatus (device body). The process means is a means for forming an image, and the devices that act on the drum mainly include a developing means, a charging means, a transfer means, a static elimination means, and a cleaning means. Examples of cartridges include a process cartridge that has a drum and at least one process means and is detachably mounted in the device body as a unit, a drum cartridge that has a drum, and a developer cartridge that has a developing means. This cartridge system allows for easy toner replenishment and maintenance of the image forming apparatus.

[0006] As a configuration for transmitting a driving force from the apparatus main body to the cartridge, there is one using a gear as shown in Patent Document 1, and one using a coupling as shown in Patent Document 2. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 63-4252 [Patent Document 2] JP 8-328449 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention (the present disclosure) aims to develop a photoreceptor unit, a cartridge, or an electrophotographic image forming apparatus. [Means for solving the problem]

[0009] The present invention (present disclosure) provides a photosensitive member unit detachable from a main body of an image forming apparatus having at least a first main body side helical gear portion and a second main body side helical gear portion that rotate coaxially, the photosensitive member being rotatable around a rotation axis, a first unit side helical gear portion for meshing with the first main body side helical gear portion, and a second unit side helical gear portion for meshing with the second main body side helical gear portion, wherein the twist direction of the teeth of the second unit side helical gear portion is the same as the twist direction of the teeth of the first unit side helical gear portion, and the twist angle of the teeth of the second unit side helical gear portion is larger than the twist angle of the teeth of the first unit side helical gear portion, the first unit side helical gear portion and the second unit side helical gear portion are disposed at one end of the photosensitive unit with respect to the direction of the rotation axis of the photosensitive body; The first unit side helical gear portion and the second unit side helical gear portion rotate in a state in which the first unit side helical gear portion meshes with the first main body side helical gear portion and the second unit side helical gear portion meshes with the second main body side helical gear portion. The rotational driving force received by the first unit side helical gear portion is transmitted to the photosensitive member, and the photosensitive member rotates. A photoreceptor unit characterized by the above is disclosed. [Effects of the Invention]

[0010] According to the present invention (the present disclosure), a photoreceptor unit, a cartridge, or an electrophotographic image forming apparatus can be improved. [Brief explanation of the drawings]

[0011] [Figure 1] A perspective view of a portion that transmits drive force from the main body of the apparatus to the drum unit. [Figure 2] Schematic cross-sectional view of the device body and cartridge [Figure 3] Cartridge cross section [Figure 4] Exploded perspective view of the cartridge [Figure 5] Exploded perspective view of the cartridge [Figure 6] Exploded perspective view of the cleaning unit [Figure 7] Cross-sectional view of the drive section from the device main body to the cartridge [Figure 8] Cross-sectional view of the device body [Figure 9] Cross-sectional view of the device body [Figure 10] Cross-sectional view of the device body [Figure 11] Exploded perspective view of the device body [Figure 12] A perspective view of a drive transmission unit of the device main body [Figure 13] Schematic diagram of the drive transmission gear of the device body [Figure 14] Schematic diagram of the drive transmission configuration from the drive transmission gear to the drive-side flange [Figure 15] FIG. 10 is a diagram showing a drive transmission configuration from a drive-side flange to a developing roller; [Figure 16] Schematic diagram of the drive transmission gear and drive-side flange, cross-sectional view of the drive transmission gear [Figure 17] Cross-sectional view of the drive transmission gear and drive-side flange [Figure 18] Cross-sectional view of the drive transmission gear and drive-side flange [Figure 19] Side view of the drive transmission gear and drive flange [Figure 20]Side view of the drive transmission gear and drive flange [Figure 21] Diagram showing the drive transmission gear and drive side flange [Figure 22] Diagram showing the drive transmission gear and drive side flange [Figure 23] Cartridge cross section [Figure 24] Schematic diagram of drive transmission configuration [Figure 25] Diagram showing the drive transmission configuration [Figure 26] Cross-sectional view of the drive transmission section [Figure 27] Graph showing the amount of deformation of the coupling drive and the drive transmission gear [Figure 28] Diagram showing the retraction mechanism [Figure 29] Schematic diagram showing the engagement between the drive side flange and the developing roller gear [Figure 30] Perspective view of the cartridge [Figure 31] Cross-sectional view of the drive transmission gear and drive-side flange [Figure 32] Diagram showing the drive side flange [Figure 33] Cross-sectional view of the drive flange and drive transmission gear, and a graph showing the changes in the number of teeth of the meshing gears [Figure 34] Cross-sectional view of the drive flange and drive transmission gear, and a graph showing the changes in the number of teeth of the meshing gears [Figure 35] Perspective view of the drive side flange [Figure 36] Schematic diagram showing the engagement between the drive transmission gear and the drive-side flange [Figure 37] Perspective view of an image forming apparatus [Figure 38] Schematic diagram showing the engagement between the drive transmission gear and the drive-side flange [Figure 39] Cross-sectional view of the drive transmission gear and drive-side flange [Figure 40] Cross-sectional view of the drive transmission gear and drive-side flange [Figure 41] Cross-sectional view of the drive transmission gear and drive-side flange [Figure 42] A perspective view of the drive-side flange and a cross-sectional view of the drive transmission gear and the drive-side flange. [Figure 43] Cross-sectional view of the drive flange, cross-sectional view of the drive transmission gear and drive flange [Figure 44] Partial perspective view of the cartridge [Figure 45] A partial cross-sectional view of the vicinity of the drum of the cartridge, showing the drum and the developing roller. [Figure 46] Cross-sectional view of the drive transmission gear and drive-side flange [Figure 47] Schematic diagram of drive transmission gear and drive side flange [Figure 48] Cross-sectional view of the drive flange, cross-sectional view of the drive transmission gear and drive flange [Figure 49] Graph showing drive transmission error when misaligned [Figure 50] Schematic cross-sectional view of the device body and cartridge [Figure 51] Exploded perspective view of the cleaning unit [Figure 52] A perspective view of a drum bearing member, a cross-sectional view of a drive-side flange and the drum bearing member, and a partial cross-sectional view of a cartridge. [Figure 53] Exploded perspective view of the device body [Figure 54] Schematic cross-sectional view of a gear portion of a drive transmission gear, a schematic cross-sectional view of a gear portion of a drive-side flange, and a schematic cross-sectional view of a gear portion of a drive transmission gear and a gear portion of a drive-side drum flange. [Figure 55] Schematic cross-sectional view of the gear part of the drive transmission gear and the gear part of the drive-side drum flange [Figure 56] A perspective view of a drive train that drives a developing roller, a partial perspective view of a developing unit, and a perspective view of a cartridge. [Figure 57] Partial perspective view of the device main body [Figure 58] Cross-sectional view of the cleaning unit and drive transmission gear [Figure 59] Partial perspective view of the cartridge [Figure 60] Cross-section of the drum unit [Figure 61] Partial perspective view of the drum unit [Figure 62] Cross-sectional view of the second gear section and the second main body gear section [Figure 63] Partial perspective view of the drum unit [Figure 64] Side view of the cleaning unit [Figure 65] Exploded perspective view of the cleaning unit [Figure 66] Partial cross-sectional view of the cleaning unit [Figure 67] Partial cross-sectional view of the cleaning unit [Figure 68] 1 is a cross-sectional view showing an engagement state between the drum unit and the drive transmission gear; [Figure 69] 1 is a cross-sectional view showing an engagement state between the drum unit and the drive transmission gear; [Figure 70] Exploded perspective view of the cleaning unit [Figure 71] 1 is a cross-sectional view showing an engagement state between the drum unit and the drive transmission gear; [Figure 72] Partial perspective view of the drum unit [Figure 73] Exploded perspective view of the cleaning unit [Figure 74] Diagram showing the drum unit meshing with the drive transmission gear [Figure 75] 1 is a cross-sectional view showing an engagement state between the drum unit and the drive transmission gear; [Figure 76] Partial perspective view of the drum unit [Figure 77] An exploded perspective view of a cleaning unit and a drum unit [Figure 78] Cross-sectional view of the cleaning unit [Figure 79] 1 is a cross-sectional view showing an engagement state between the drum unit and the drive transmission gear; [Figure 80] 1 is a cross-sectional view showing an engagement state between the drum unit and the drive transmission gear; [Figure 81] Partial perspective view of the drum unit [Figure 82] Partial perspective view of the drum unit [Figure 83] Partial perspective view of the drum unit [Figure 84] Cross-section of the drum unit [Figure 85]A diagram showing the drum unit attached to the cleaning unit [Figure 86] Cross section of the drive flange and drive transmission gear [Figure 87] Cross section of the drive flange and drive transmission gear [Figure 88] Partial perspective view of the drum unit [Figure 89] Cross section of drive side flange [Figure 90] A diagram showing the drum unit attached to the cleaning unit [Figure 91] Cross section of the drive flange and drive transmission gear [Figure 92] Side view of the cleaning unit [Figure 93] An exploded perspective view of the cleaning unit and the drive-side drum flange. [Figure 94] Exploded perspective view of a drum bearing unit [Figure 95] Partial cross-sectional view of the cleaning unit [Figure 96] Diagram showing the cleaning unit [Figure 97] Partial cross-sectional view of the cleaning unit [Figure 98] Diagram showing the cartridge and the device body [Figure 99] FIG. 10 shows the drive-side drum flange 2463 engaging with the drive transmission gear. [Figure 100] Schematic cross-sectional view of the engagement area between the drive-side drum flange and the drive transmission gear [Figure 101] Diagram showing the cleaning unit [Figure 102] An exploded perspective view of a cleaning unit and a drum unit [Figure 103] Partial cross-sectional view of the cleaning unit [Figure 104] FIG. 1 is a perspective view showing a cleaning unit and a drive transmission gear. [Figure 105] Schematic cross-sectional view of the meshing portion between the drive gear and the idler gear and the drive transmission gear. [Figure 106]Schematic cross-sectional view of the meshing portion between the drive gear and the idler gear and the drive transmission gear. [Figure 107] Schematic cross-sectional view of the meshing portion between the drive gear and the idler gear and the drive transmission gear. [Figure 108] An exploded perspective view of a cleaning unit and a drum unit [Figure 109] FIG. 10 is a diagram showing an engagement state between the cleaning unit and the drive transmission gear; [Figure 110] A view of the cartridge along the direction of the drum's rotation axis [Figure 111] A perspective view of a drive transmission mechanism of the cartridge [Figure 112] 10 is a perspective view of another example of the drive transmission gear; [Figure 113] Cartridge illustration [Figure 114] Cartridge illustration DETAILED DESCRIPTION OF THE INVENTION

[0012] [Example 1] <Overall configuration of image forming apparatus> 2 is a cross-sectional view of an electrophotographic image forming apparatus (image forming apparatus) 100, the cross section being perpendicular to a rotation axis L1 of a photosensitive drum 62 (described later). The image forming apparatus 100 is a laser beam printer that uses electrophotography, and a cartridge B having a photosensitive drum 62 is removably mounted in an apparatus main body A. In other words, the portion of the image forming apparatus 100 excluding the cartridge B is the apparatus main body A. When the cartridge B is mounted in the apparatus main body A, it is possible to form an image on a recording medium (sheet material) PA such as paper.

[0013] <Device configuration> The apparatus main body A has an exposure device (laser scanner unit) 3 and a sheet tray 4 that stores sheet material PA. Furthermore, the apparatus main body A has, along the conveying direction D of the sheet material PA, a pickup roller 5a, a pair of conveying rollers 5b, a transfer guide 6, a transfer roller 7, a conveying guide 8, a fixing device 9, a pair of discharge rollers 10, and a discharge tray 11. The fixing device 9 has a heating roller 9a and a pressure roller 9b.

[0014] <Cartridge configuration> Next, the overall configuration of cartridge B will be described with reference to Figures 3, 4, 5, 6, and 7. Figure 3 is a cross-sectional view of cartridge B, which is a cross-section perpendicular to the rotation axis L1 of a photosensitive drum 62 (described later). Figures 4 and 5 are exploded perspective views illustrating the configuration of cartridge B. Figure 6(a) is an exploded perspective view illustrating the configuration of a drum unit 69. Figure 6(b) is an exploded perspective view illustrating the configuration of a cleaning unit. Figure 7 is a cross-sectional view of a drive section that transmits drive from image forming apparatus A to cartridge B. Note that in this embodiment, screws and the like used to connect the various parts will not be described.

[0015] Cartridge B is a process cartridge, and mainly includes an electrophotographic photosensitive member and process means acting thereon. The process means are charging means, developing means, and cleaning means, which will be described later. Cartridge B is structured mainly to include a cleaning unit (drum unit) 60 and a developing unit 20, and the electrophotographic photosensitive member and process means are provided in the cleaning unit 60 or the developing unit 20.

[0016] The longitudinal direction of the drum 62 is parallel to the direction of the rotation axis L1 of the drum 62 (rotation axis direction). The side of the drum 62 to which the driving force is transmitted from the main assembly A of the apparatus with respect to the rotation axis direction is called the drive side, and the opposite side is called the non-drive side. The direction from the non-drive side to the drive side along the rotation axis L1 of the drum 62 (parallel to the rotation axis L1) is called the J direction, and the direction from the drive side to the non-drive side is called the H direction. When the J direction and H direction are defined in the main assembly A of the apparatus, they are defined so as to coincide with the J direction and H direction defined when the cartridge B is mounted in the main assembly A of the apparatus.

[0017] <Cleaning unit (drum unit)> 3, the cleaning unit (drum unit) 60 includes a photosensitive drum 62, a charging roller 66, a cleaning member 77, and a cleaning frame (drum frame) 60a that supports these components. The cleaning frame (drum frame) 60a includes a frame member 71 and a drum bearing member 73.

[0018] As shown in Figure 6(a), the photosensitive drum (drum) 62, which is a rotating body, is a cylindrical electrophotographic photosensitive body, and is made by coating a photosensitive layer on the outer surface of an aluminum cylinder. A drive-side flange (driving force receiving member) 63 is fixed by crimping to the drive-side (one end) end of the drum 62, and a non-drive-side flange 64 is fixed by crimping to the non-drive-side (other end) end. The drum 62, drive-side flange 63, and non-drive-side flange 64 integrated in this way (i.e., a unit that can rotate integrally with the drum 62) is called a drum unit 69.

[0019] In general, the cleaning unit 60 may also be called a drum unit, but in this case, this is the name given when the cleaning unit 60 as a whole is recognized as a unit having a drum 62 that is paired with the development unit 20 having the developing means when roughly classifying the contents of the cartridge B. Therefore, the drum unit as the name given to the cleaning unit 60 as a whole is a different concept from the drum unit 69 (a unit that can rotate integrally with the drum 62) in this embodiment. In the following explanation, the drum unit refers to a unit that can rotate integrally with the drum 62.

[0020] The drum 62, drive-side flange 63, and non-drive-side flange 64 rotate integrally around the drum's rotation axis L1. In other words, the rotation axes of the drive-side flange 63, non-drive-side flange 64, and drum unit 69 are coaxial with the rotation axis L1 of the drum 62. For this reason, hereinafter, the rotation axes of the drum 62, drive-side flange 63, non-drive-side flange 64, and drum unit 69 assembled into the drum unit 69 will all be referred to as the rotation axis L1.

[0021] The drive-side flange 63 and the non-drive-side flange 64 are also fixed together in the direction of the rotation axis L1. The drive-side flange 63 and the non-drive-side flange 64 are made of resin. The drive-side flange 63 includes a first gear portion 63c and a second gear portion 63d, which will be described in detail later.

[0022] As shown in FIG. 6(b), the drum unit 69 is supported by the drum frame 60a (frame member 71 and drum bearing member 73) to be rotatable about the rotation axis L1. Specifically, the drive-side flange 63 has a hole 63g coaxial with the rotation axis L1, and a shaft member 86 press-fitted into the drum bearing member 73 is inserted into the hole 63g, thereby rotatably supporting the drum bearing member 73. The non-drive-side flange 64 has a hole (not shown) coaxial with the rotation axis L1, and a shaft member 78 press-fitted into the hole 71c of the frame member 71 is inserted into this hole, thereby rotatably supporting the non-drive-side flange 64 on the frame member 71. In this way, the non-drive-side flange 64 and the drive-side flange 63 are supported portions rotatably supported by the shaft members 86 and 78.

[0023] As shown in FIG. 7, the second gear portion 63d of the drive-side flange 63 includes a protrusion 63d1 protruding in the H direction on its downstream end surface in the H direction, and a protrusion 63f protruding in the J direction on its upstream end surface in the H direction (downstream in the J direction). The frame member 71 includes a rib 71p and a side wall 71m extending in a direction perpendicular to the rotation axis L1. The protrusion 63d1 is capable of contacting the side surface of the rib 71p, and the protrusion 63f is capable of contacting the side surface of the side wall 71m. The drive-side flange 63 is slidably fitted between the rib 71p and the side wall 71m with a clearance fit. Therefore, there may be cases where the protrusion 63d1 contacts the side surface of the rib 71p and cases where the protrusion 63f contacts the side surface of the side wall 71m. However, the fitting play (gap) is set to be extremely small (maximum approximately 150 μm), and it can be said that the drive-side flange 63 is positioned at substantially the same position in both cases. In this way, it can be said that the drum unit 69 including the driving side flange 63 is positioned relative to the drum frame 60a in the direction of the rotation axis L1 by the rib 71p or the side wall 71m.

[0024] In this embodiment, the longitudinal direction of the cartridge B, the drum frame 60a, and the frame member 71 is parallel to the direction of the rotation axis L1 of the drum 62.

[0025] As shown in FIG. 3, in the cleaning unit 60, a charging roller (charging member) 66 serving as a charging means and a cleaning member 77 serving as a cleaning means are disposed in contact with the outer peripheral surface of the drum 62. The cleaning member 77 includes a rubber blade 77a, which is a blade-shaped elastic member made of rubber as an elastic material, and a support member 77b that supports the rubber blade 77a. The rubber blade 77a contacts the drum 62 in a counter-direction relative to the rotational direction of the drum 62. That is, the rubber blade 77a contacts the drum 62 with its tip facing upstream in the rotational direction of the drum 62. Waste toner removed from the surface of the drum 62 by the cleaning member 77 is collected (accumulated) in a waste toner chamber 71b formed by the frame member 71 and the cleaning member 77. A sheet 65 for preventing waste toner from leaking from the gap between the frame member 71 and the drum 62 is attached to the edge of the frame member 71 so as to contact the drum 62.

[0026] The charge roller 66 is rotatably supported at both ends in the direction of its rotation axis by charge roller bearings 67 supported by frame members 71. The rotation axis of the charge roller 66 is approximately parallel to the rotation axis L1 of the drum 62. The charge roller 66 is pressed against the drum 62 by the charge roller bearings 67 being pressed toward the drum 62 by a biasing member 68. The charge roller 66 rotates following the rotation of the drum 62.

[0027] <Developing unit> 3, the developing unit 20 includes a developing roller 32, a magnet roller 34, a developing blade 42, a conveying member 43, and a developing frame 20a that supports these components. The developing frame 20a includes a developing container 23, a bottom member 22, a bearing member 24 (see FIG. 5), a bearing member 37 (see FIG. 4), a developing side cover 26 (see FIG. 4), and a developing side cover 27 (see FIG. 5). Inside the developing unit 20, a toner supply chamber 28 and a toner chamber 29 are formed by the developing container 23 and the bottom member 22.

[0028] As shown in Figures 4 and 5, inside the toner supply chamber 28, the developing roller 32 is rotatably supported at both ends in the direction of its rotation axis by bearing members 24 and 37. Bearing members 24 and 37 are attached to the developer container 23. The developing roller (developing member) 32 serving as developing means is a cylindrical member, inside which a magnet roller 34 is disposed. A developing blade 42 is disposed to define (regulate) the thickness of the toner (toner layer) carried on the surface of the developing roller 32.

[0029] The developing roller 32 has spacing members 38 attached to both ends in the direction of its rotation axis, and the spacing members 38 come into contact with the surface of the drum 62, thereby determining the distance between the surface of the developing roller 32 and the surface of the drum 62. Specifically, the distance is determined so that a minute gap is formed between the surface of the developing roller 32 and the surface of the drum 62.

[0030] 3, a sheet 33 for preventing toner leakage from the gap between the developing frame 20a and the developing roller 32 is attached to the edge of the bottom member 22 so as to abut against the developing roller 32. Furthermore, a transport member (agitation member) 43 is rotatably provided in the toner chamber 29. By rotating, the transport member 43 agitates the toner contained in the toner chamber 29 and transports the toner from the toner chamber 29 to the toner supply chamber 28.

[0031] <Combination of cleaning unit and developing unit> The cartridge B is assembled by combining the cleaning unit 60 and the developing unit 20. As shown in FIGS. 4 and 5, first, the center of the first developer support boss 26a of the developer container 23 is aligned with the first hanging hole 71i on the drive side of the frame member 71, and the center of the second developer support boss 27a is aligned with the second hanging hole 71j on the non-drive side. Then, by moving the developing unit 20 in the direction of arrow G, the first developer support boss 26a and the second developer support boss 27a fit into the first hanging hole 71i and the second hanging hole 71j. Thereafter, by assembling the drum bearing member 73 to the cleaning unit 60, the developing unit 20 is prevented from being separated from the cleaning unit 60. This allows the developing unit 20 to be movably connected to the cleaning unit 60. Specifically, the developing unit 20 is connected to the cleaning unit 60 so as to be rotatable (pivotable) around the first developer support boss 26a and the second developer support boss 27a.

[0032] As shown in FIG. 4, the first end 46Rb of the drive-side spring (biasing member) 46R is fixed to the surface 26b of the developer side cover 26, and the second end 46Ra abuts against the surface 71k of the frame member 71 of the cleaning unit 60. As shown in FIG. 5, the first end 46Lb of the non-drive-side spring (biasing member) 46L is fixed to the surface 27b of the developer side cover 27, and the second end 46La abuts against the surface 71l of the frame member 71. The non-drive-side spring 46L and the drive-side spring 46R are compression springs. The biasing forces of these springs generate a biasing force between the developing frame 20a and the cleaning frame 60a so as to press the developing roller 32 toward the drum 62. As a result, as described above, the spacing member 38 is pressed against the surface of the drum 62, maintaining a predetermined gap between the surface of the developing roller 32 and the surface of the drum 62.

[0033] <Image formation process> Next, the image forming process will be described. The control unit (not shown) receives a print command signal sent from a host computer or the like, and generates a print start signal based on that signal, thereby starting the image forming process.

[0034] When the image formation process begins, the drum 62 is first rotated in the direction of arrow R (see FIGS. 2 and 3) at a predetermined peripheral speed (process speed). A charging bias voltage is applied to the charging roller 66, which substantially uniformly charges the surface (outer periphery) of the drum 62. Furthermore, as shown in FIG. 2, the exposure device (exposure means) 3 emits laser light L corresponding to the image information to be printed. The laser light L passes through a laser opening 71h provided in the frame member 71 of the cartridge B and is irradiated onto the surface of the drum 62 charged by the charging roller 66, scanning the surface of the drum 62 with the laser light L. As a result, an electrostatic latent image corresponding to the image information is formed on the photosensitive layer on the surface of the drum 62.

[0035] Meanwhile, as shown in FIG. 3, in the developing unit 20, toner (developer) T in the toner chamber 29 is stirred and transported by the rotation of the transport member 43 and sent to the toner supply chamber 28. The toner T is carried on the surface of the developing roller 32 by the magnetic force of the magnet roller (fixed magnet) 34. The developing roller 32 is a developer carrier that carries the toner T on its surface and visualizes (develops) the electrostatic latent image formed on the drum 62 described above. The toner T is frictionally charged by the developing blade 42, which further regulates the thickness of the toner T layer on the circumferential surface of the developing roller 32 to a desired thickness. The toner T carried on the surface of the developing roller 32 is then supplied to and adheres to the area of ​​the drum 62 corresponding to the electrostatic latent image. As a result, the electrostatic latent image on the drum 62 is visualized (developed) as a toner image. The drum 62 can be considered an image carrier that carries an electrostatic latent image and a toner image (developer image) on its surface.

[0036] 2, in synchronization with the output timing of the laser beam L, a sheet material PA stored in a sheet tray 4 at the bottom of the apparatus main body A is sent to a conveying path within the apparatus main body A by a pickup roller 5a and a pair of conveying rollers 5b. Thereafter, the sheet material PA is guided by a transfer guide 6 and conveyed to a transfer nip between a drum 62 and a transfer roller (transfer means) 7. In this transfer nip, the toner image formed on the drum 62 is transferred onto the sheet material PA.

[0037] The sheet material PA, which has passed through the transfer nip and onto which the toner image has been transferred, is guided by a conveying guide 8 and conveyed to a fixing device (fixing means) 9. The sheet material PA then passes through a fixing nip between a heating roller 9a and a pressure roller 9b of the fixing device 9. In this fixing nip, the sheet material PA is pressurized and heated, thereby fusing and fixing the toner image to the sheet material PA. After passing through the fixing nip, the sheet material PA is conveyed to a pair of discharge rollers 10 and discharged onto a discharge tray 11.

[0038] 3, the surface of the drum 62 after passing through the transfer nip comes into contact with the cleaning blade 77, and toner remaining on the surface of the drum 62 is removed, making it possible to reuse the drum 62 in the image forming process described above. The toner removed from the drum 62 by the cleaning blade 77 is stored as waste toner in the waste toner chamber 71b of the cleaning unit 60.

[0039] In this embodiment, at least the charging roller 66, the exposure device 3, the developing roller 32, the transfer roller 7, and the cleaning blade 77 are process means that act on the drum 62.

[0040] <Installing and removing cartridges> Next, the installation of cartridge B into the main assembly A of the apparatus will be specifically described with reference to FIGS. 8, 9, and 10. FIG. 8(a) is a cross-sectional view of the drive side of the main assembly A of the apparatus with the door 13 open, and FIG. 8(b) is a cross-sectional view of the non-drive side of the main assembly A of the apparatus with the door 13 open. The cross sections shown in FIGS. 8(a) and 8(b) are cross-sectional views perpendicular to the rotation axis L1. FIG. 9 is a diagram for explaining the positioning of cartridge B in the longitudinal direction (the direction of the rotation axis L1), and is a cross-sectional view of the fitting portion 15j of the main assembly A of the apparatus taken along a horizontal plane parallel to the rotation axis L1 (a plane parallel to the installation surface of the main assembly A of the apparatus). FIG. 9(a) shows the state immediately before cartridge B is fitted into fitting portion 15j, and FIG. 9(b) shows the state after cartridge B has fitted into fitting portion 15j. Fig. 10(a) is a cross-sectional view of the drive side of the device body A with the door 13 closed, and Fig. 10(b) is a cross-sectional view of the non-drive side of the device body A with the door 13 closed. The cross sections shown in Fig. 10(a) and Fig. 10(b) are cross sections perpendicular to the rotation axis L1.

[0041] First, the installation of cartridge B into the main assembly A of the apparatus will be described. The main assembly A of the apparatus is provided with a first drive-side side plate 15 and a non-drive-side side plate 16, which sandwich the cartridge B installed in the main assembly A in the direction of the rotation axis L1. A door 13 for opening and closing an insertion slot 17 is also rotatably attached to the main assembly A of the apparatus. The first drive-side side plate 15 has an upper guide rail 15g and a lower guide rail 15h that guide cartridge B when installing and removing cartridge B. The non-drive-side side plate 16 has an upper guide rail 16d and a lower guide rail 16e that guide cartridge B when installing and removing cartridge B. Furthermore, the drum bearing member 73 of cartridge B is provided with a guided portion 73g and a rotation-stopped portion 73c, and the frame member 71 has a positioned portion 71d and a rotation-stopped portion 71g. Therefore, the guided portion 73g and the rotation-stopped portion 73c are arranged on the drive side of the cartridge B, and the guided portion 73g and the rotation-stopped portion 73c are arranged on the non-drive side of the cartridge B, respectively.

[0042] When the door 13 of the apparatus main body A is opened to expose the insertion opening 17 formed between the first drive-side side plate 15 and the non-drive-side side plate 16, the cartridge B can be inserted into or removed from the apparatus main body A through the insertion opening 17. At this time, the cartridge B can be inserted into, attached to, or removed from the apparatus main body A by moving the cartridge B in a direction substantially perpendicular to the rotation axis L1 of the drum 62. In other words, the mounting direction M of the cartridge B into the apparatus main body A (see FIG. 9(a)) and the removal direction from the apparatus main body A (the opposite direction to the mounting direction M) are directions substantially perpendicular to the rotation axis L1. Because the rotation axis L1 of the cartridge B mounted in the apparatus main body A is parallel to the rotation axis L2 of the drive transmission gear 81, it can also be said that the mounting direction M of the cartridge B into the apparatus main body A and the removal direction from the apparatus main body A are directions substantially perpendicular to the rotation axis L2. Furthermore, when cartridge B is mounted to or removed from the apparatus main body A, drum unit 69 moves integrally with cartridge B relative to the apparatus main body A, and is mounted to or removed from the apparatus main body A. Therefore, the mounting direction of drum unit 69 to and removing direction from the apparatus main body A are the same as the mounting direction M of cartridge B to and removing direction from the apparatus main body A, respectively.

[0043] <Cartridge installation and positioning> When cartridge B is inserted into the apparatus main body A through cartridge insertion opening 17, guided portion 73g and rotation-stopped portion 73c on the drive side of cartridge B are guided by upper guide rail 15g and guide rail 15h, respectively. Positioned portion 71d and rotation-stopped portion 71g on the non-drive side of cartridge B are guided by upper guide rail 16d and lower guide rail 16e. Cartridge B is inserted while being guided by the guide rails of the apparatus main body A in this way, and finally, installation of cartridge B into the apparatus main body A is completed.

[0044] As shown in Figures 9(a) and 9(b), the drum bearing member 73 has a fitted portion 73h as a positioned portion (axially positioned portion) that is positioned relative to the device main body A in the direction of the rotation axis L1. The fitted portion 73h has a concave shape (or a groove or slit shape) that is recessed in the mounting direction M (a direction perpendicular to the rotation axis L1). On the other hand, the first drive-side side plate 15 of the device main body A has a fitting portion 15j that can fit into the fitted portion 73h. The fitting portion 15j has a convex shape that protrudes in the opposite direction to the mounting direction MD.

[0045] During the process of inserting cartridge B into the apparatus main assembly A, as shown in Figure 9(b), the mated portion 73h mates with the mating portion 15j, thereby determining the position of cartridge B in the direction of rotation axis L1 (longitudinal direction of cartridge B). Note that although the mated portion 73h and the mating portion 15j are fitted together with a clearance fit, the mating play (gap) is set to be extremely small (maximum of approximately 150 μm). Therefore, whether the mated portion 73h abuts against the mating portion 15j in the H direction or the J direction, it can be said that cartridge B is positioned at substantially the same position in the direction of rotation axis L1.

[0046] 8(a), 8(b), 10(a), and 10(b), the first drive-side side plate 15 has positioning portions 15a, 15b, and a rotation stopper portion 15c, and the non-drive-side side plate 16 has positioning portions 16a, 16b, and a rotation stopper portion 16c. Cartridge pressing members 1 and 2 are attached to both ends of the door 13 in the direction of the rotation axis of the door 13 so as to be movable (rotatable) relative to the door 13. Pressing springs 19 and 21 are attached to the first drive-side side plate 15 and the non-drive-side side plate 16, respectively.

[0047] 3, the drum bearing member 73 of the cartridge B has a pressed portion (urging force receiving portion) 73e, and the frame member 71 has a pressed portion (urging force receiving portion) 71n. The pressed portions 73e and 71n are provided in recessed portions arranged on the driving side and non-driving side of the cartridge B, respectively.

[0048] 10(a) and 10(b), by closing the door 13, the cartridge pressing members 1 and 2 are urged toward the cartridge B by the pressing springs 19 and 21. Then, the cartridge pressing members 1 and 2 come into contact with the pressed portions 73e and 71n, and press the pressed portions 73e and 71n by the urging forces of the pressing springs 19 and 21.

[0049] As a result, on the drive side, positioned portion 73g of cartridge B abuts against positioning portions 15a and 15b of the main assembly A of the apparatus, and rotation stop portion 73c abuts against rotation stop portion 15c of the main assembly A of the apparatus. As a result, the drive side portion of drum frame 60a of cartridge B is positioned in a direction perpendicular to rotation axis L1, and rotation about an axis parallel to rotation axis L1 is restricted. On the non-drive side, positioned portion 71d of cartridge B abuts against positioning portions 16a and 16b of the main assembly A of the apparatus, and rotation stop portion 71g abuts against rotation stop portion 16c of the main assembly A of the apparatus. As a result, the non-drive side portion of drum frame 60a of cartridge B is positioned in a direction perpendicular to rotation axis L1, and rotation about an axis parallel to rotation axis L1 is restricted.

[0050] By positioning the drum frame 60a of the cartridge B relative to the main assembly A of the apparatus in this manner, the drum unit 69 positioned relative to the drum frame 60a is also indirectly positioned relative to the main assembly A of the apparatus.

[0051] <Drive transmission to the drum unit> Next, the configuration for transmitting drive from the apparatus main body A to the drum unit 69 and the drum 62 will be described. FIG. 1 is a perspective view of the portion for transmitting drive from the apparatus main body A to the drum unit 69. FIG. 11 is an exploded perspective view showing the support configuration for the drive transmission gear 81 of the apparatus main body A. FIG. 12 is a perspective view showing the drive transmission portion of the apparatus main body A. FIG. 13(a) is a diagram schematically showing the drive transmission gear 81 of the apparatus main body A. FIG. 13(b) is a diagram schematically showing the drive side flange 63 of the cartridge B. Note that in FIGS. 13(a) and 13(b), the ridge lines of the tooth tips are shown for the gear teeth. FIG. 14 is a diagram schematically showing the drive transmission configuration from the drive transmission gear 81 of the apparatus main body A to the drive side flange 63 of the cartridge B.

[0052] <Drive configuration of the device main body> As shown in FIG. 11 , the apparatus main assembly A includes a motor (not shown), an idler gear 80, a drive transmission gear 81, a second drive-side side plate 83, a main frame 84, a drive shaft 82, and a compression spring 85. Driving force from the motor is transmitted from the idler gear 80 to the drive transmission gear 81. The idler gear 80 and the drive transmission gear 81 are supported by the drive shaft 82 so as to be coaxially rotatable with each other and movable in the direction of the rotation axis. One end 82a of the drive shaft 82 is fixed in a hole 83a in the second drive-side side plate 83, and the other end 82b is supported in a hole 84a in the main frame 84. The drive shaft 82 is disposed so that the rotation axis of the drive transmission gear 81 is parallel to the rotation axis L1 of the drum 62 when the cartridge B is attached to the apparatus main assembly A.

[0053] Furthermore, a compression spring 85 is provided between the other end 80b of the idler gear 80 and the second drive-side side plate 83, and the idler gear 80 is biased in the H direction in the direction of the rotation axis. As described above, the J direction and H direction in the apparatus main body A are defined so as to coincide with the J direction and H direction of the cartridge B mounted in the apparatus main body A. As a result, as shown in Figure 11, the J direction is the direction from the idler gear 80 toward the second drive-side side plate 83 along the rotation axis of the idler gear 80, and the H direction is the opposite direction.

[0054] One end 80a of the idler gear 80 is provided with a recess 80a1 recessed in the direction of the rotation axis. Meanwhile, one end 81a of the drive transmission gear 81 is provided with a protrusion 81a1 protruding in the direction of the rotation axis at a location facing the recess 80a1 of the idler gear 80. When the recess 80a1 of the idler gear 80 and the protrusion 81a of the drive transmission gear 81 engage with each other, driving force is transmitted from the idler gear 80 to the drive transmission gear 81, and they rotate integrally. Note that the concave-convex relationship between the recess 80a1 and the protrusion 81a1 may be reversed.

[0055] As will be described later, the drive transmission gear 81 meshes with the drive-side flange 63 of cartridge B to transmit a drive force. As shown in Fig. 1, during the above-described image forming process, the initial operation after cartridge B is installed, and the preparatory operation for the image forming process (collectively referred to as "during driving"), the drive transmission gear 81 rotates in the I direction, and the drive-side flange 63 rotates in the K direction. In other words, the drive direction (rotation direction) of the drive transmission gear 81 during driving is the I direction, and the drive direction (rotation direction) of the drive-side flange 63 during driving is the K direction. When viewing the drive transmission gear 81 and the drive-side flange 63 from the drive side to the non-drive side along the H direction, the I direction is clockwise, and the K direction is counterclockwise.

[0056] <Drive transmission gear 81> As shown in Figures 1, 12, and 13(a), the drive transmission gear 81 includes a first main body gear portion (first main body side gear portion, first main body side helical gear portion) 81c and a second main body gear portion (second main body side gear portion, second main body side helical gear portion) 81d, which are coaxially arranged as helical gear portions. The first main body gear portion 81c is located downstream in the H direction (upstream in the J direction) of the second main body gear portion 81d. The first main body gear portion 81c includes a plurality of first main body helical teeth 81ct, and the second main body gear portion 81d includes a plurality of second main body helical teeth 81dt. Note that both the first main body helical teeth 81ct and the second main body helical teeth 81dt are involute tooth profiles. The first main body gear portion 81c and the second main body gear portion 81d are integrally molded from resin and rotate integrally. The first body gear portion 81c and the second body gear portion 81d are twisted in the same direction such that the tooth surfaces are displaced in the I direction as they move in the J direction. As shown in Fig. 13(a), the helix angle α2 of the second body gear portion 81d is larger than the helix angle α1 of the first body gear portion 81c (i.e., α1 < α2 is satisfied). The first body gear portion 81c and the second body gear portion 81d have the same number of teeth.

[0057] <Drive side flange 63> On the other hand, as shown in FIGS. 1, 6(b), and 13(b), the drive-side flange 63 includes a first gear portion (first unit side gear portion, first unit side helical gear portion, first helical gear portion) 63c and a second gear portion (second unit side gear portion, second unit side helical gear portion, second helical gear portion) 63d that are coaxially arranged as helical gear portions. The first gear portion 63c is disposed downstream in the H direction (upstream in the J direction) of the second gear portion 63d. In other words, the first gear portion 63c is disposed between the second gear portion 63d and the drum 62 with respect to the direction of the rotation axis L1. The first gear portion 63c includes a plurality of first helical teeth (first protrusions) 63ct that are disposed at different positions in the circumferential direction about the rotation axis L1, and the second gear portion 63d includes a plurality of second helical teeth (second protrusions) 63dt that are disposed at different positions in the circumferential direction about the rotation axis L1. The first helical teeth 63ct and the second helical teeth 63dt are both involute tooth profiles and protrusions that protrude radially from the rotation axis L1. The first gear portion 63c and the second gear portion 63d are integrally molded from resin and rotate integrally. Therefore, the first gear portion 63c and the second gear portion 63d can also be considered as a first rotating portion and a second rotating portion that rotate integrally with each other. The first gear portion 63c meshes with the first main gear portion 81c of the drive transmission gear 81, and the second gear portion 63d meshes with the second main gear portion 81d of the drive transmission gear 81.

[0058] As shown in FIG. 1, the twist directions of the first gear portion 63c and the second gear portion 63d of the drive-side flange 63 are the same, with the tooth surfaces gradually shifting in the K direction as they move in the J direction. The twist directions of the first gear portion 63c and the second gear portion 63d are opposite to the twist directions of the first main gear portion 81c and the second main gear portion 81d of the drive transmission gear 81. As shown in FIG. 13(b), the twist angle α2 of the second gear portion 63d is larger than the twist angle α1 of the first gear portion 63c (i.e., α1 < α2 is satisfied). The twist angle α1 of the first gear portion 63c is the same as the twist angle α1 of the first main gear portion 81c, and the twist angle α2 of the second gear portion 63d is the same as the twist angle α2 of the second main gear portion 81d. The first gear portion 63c and the second gear portion 63d of the drive-side flange 63 have the same number of teeth. The width (tooth width) W63c (Wc, Wc1) of the first helical teeth (first protrusions) 63ct in the direction of the rotation axis L1 is greater than the width (tooth width) W63d (Wd) of the second helical teeth (second protrusions) 63dt in the direction of the rotation axis L1. That is, each of the first gear portion 63c and the second gear portion 63d has at least one tooth such that the face width Wc of the first helical teeth (tooth, first protrusions) 63ct and the face width Wd of the second helical teeth (tooth, second protrusions) 63dt in the direction of the rotation axis L1 satisfy the following formula A1: Wc>Wd (Eq. A1)

[0059] In other words, when the width (tooth width) of the first helical tooth 63ct, which has the widest width (tooth width) in the direction of the rotation axis L1 of the first gear portion 63c, is defined as Wc1, the second gear portion 63d has a second helical tooth (second protrusion) 63dt whose width (tooth width) in the direction of the rotation axis L1 is smaller than Wc1.

[0060] As will be described in detail later, while the drive side flange 1763 is driven by the drive transmission gear 1781 in a balanced state, the drive force FD received by the first gear portion 1763c is greater than the regulating force FB received by the second gear portion 1763d, so such a relationship is preferable.

[0061] Furthermore, the larger the meshing width (meshing width) of the rotation axis L1 of the meshing (contact) portion of the first gear portion 63c with the first main body gear portion 81c and the meshing width of the second helical gear portion 63c with the second main body gear portion 81d, the better the drive transmission accuracy. However, if the meshing width is set larger than necessary, the widths of the first gear portion 63c and the second gear portion 63c in the direction of the rotation axis L1 will increase, resulting in an increase in the size of the drive-side flange 63, the drum unit 69, the cartridge B, and ultimately the apparatus main body A. Therefore, it is preferable that the tooth width Wc1 of the first helical tooth (tooth) 63ct, which has the widest tooth width in the first gear portion 63c, and the tooth width Wd1 of the second helical tooth (tooth) 63dt, which has the widest tooth width in the second gear portion 63d, satisfy the following formula A2, more preferably formula A3: Wd1≦(4 / 5)·Wc1···(Formula A2) Wd1≦(3 / 4)·Wc1···(Formula A3)

[0062] Furthermore, from the viewpoint of the strength of the second helical teeth (teeth) 63dt of the second gear portion 63d, it is preferable that the second helical teeth (teeth) 63dt have a certain degree of tooth width or more, and it is preferable that the tooth width Wc1 and the tooth width Wd1 satisfy the following formula A4. Wd1≧(1 / 10)·Wc1···(Formula A4)

[0063] Furthermore, as shown in Figure 14, the meshing pitch circle diameters D63c and D63d of the first gear portion 63c and the second gear portion 63d when the drive-side flange 63 and the drive transmission gear 81 mesh are set to be approximately the same. The tooth tip circle diameters Dt63c and Dt63d of the first gear portion 63c and the second gear portion 63d are also set to be approximately the same. Similarly, the meshing pitch circle diameters D81c and D81d of the first main gear portion 81c and the second main gear portion 81d are also set to be approximately the same. This allows the first gear portion 63c and the first main gear portion 81c to mesh properly, and the second gear portion 63d and the second main gear portion 81d to mesh properly without tooth tip contact.

[0064] In order to set the meshing pitch circle diameters D63c and D63d of the first gear portion 63c and the second gear portion 63d to be substantially the same, it is preferable to determine the shapes of the first gear portion 63c and the second gear portion 63d as follows.

[0065] Specifically, it is preferable that the size of the tip diameter Dt63c of the first gear portion 63c be set to a value larger than the root diameter Db63d of the second gear portion 63d or a value larger than 0.8 times (more preferably 0.9 times) the tip diameter Dt63d of the second gear portion 63d. Also, it is preferable that the size of the tip diameter Dt63c of the first gear portion 63c be set to a value smaller than 1.1 times the tip diameter Dt63d of the second gear portion 63d.

[0066] Furthermore, it is preferable that the size of the root circle diameter Db63c of the first gear portion 63c be set to a value smaller than the tip circle diameter Dt63d of the second gear portion 63d, and that the size of the root circle diameter Db63c of the first gear portion 63c be set to a value larger than 0.9 times the root circle diameter Db63d of the second gear portion 63d.

[0067] Furthermore, it is preferable that the size of the tip circle diameter Dt63d of the second gear portion 63d be set to a value larger than the root circle diameter Db63c of the first gear portion 63c or a value larger than 0.8 times (more preferably 0.9 times) the tip circle diameter Dt63c of the first gear portion 63c. It is also preferable that the size of the tip circle diameter Dt63d of the second gear portion 63d be set to a value smaller than 1.1 times the tip circle diameter Dt63c of the first gear portion 63c.

[0068] Furthermore, it is preferable that the size of the root circle diameter Db63d of the second gear portion 63d be set to a value smaller than the tip circle diameter Dt63c of the first gear portion 63c. Also, it is preferable that the size of the root circle diameter Db63d of the second gear portion 63d be set to a value larger than 0.9 times the root circle diameter Db63c of the first gear portion 63c.

[0069] Here, the relationship between these dimensions is shown using the diameters of the first gear portion 63c and the second gear portion 63d, but it is obvious that the same relationship applies even if the diameters are replaced with radii. Furthermore, in the examples described later, examples will be shown in which the teeth of the first gear portion 63c and the second gear portion 63d are replaced with multiple protrusions of various shapes. In this case, the tooth tip circle is a circle that is traced as a rotation locus when the tip (point) of the multiple protrusions that is farthest from the rotation axis L1 rotates, and the diameter / radius of this circle is defined as the tooth tip circle diameter / tooth tip circle radius.

[0070] In this way, in order to make the meshing pitch circle diameters D63c, D63d the same while making the twist angles of the first gear portion 63c and the second gear portion 63d different, the modules are made different between the first gear portion 63c and the second gear portion 63d and the amount of displacement is changed. Similarly, for the drive transmission gear 81, the modules are made different between the first main body gear portion 81c and the second main body gear portion 81d and the amount of displacement is changed.

[0071] The drive-side flange 63 also includes a cylindrical portion (intermediate portion, small-diameter portion, shaft portion) 63e between the first gear portion 63c and the second gear portion 63d in the direction of the rotation axis L1. The cylindrical portion 63e has a maximum diameter D63e centered on the rotation axis L1 that is smaller than the tip diameter Dt63c of the first gear portion 63c and the tip diameter Dt63d of the second gear portion 63d. Furthermore, in this embodiment, the maximum diameter D63e of the cylindrical portion 63e centered on the rotation axis L1 is smaller than the root diameter Db63c of the first gear portion 63c and the root diameter Db63d of the second gear portion 63d. However, the maximum diameter D63e of the cylindrical portion 63e centered on the rotation axis L1 does not have to be as described above if the drive-side flange 63 does not come into contact with the drive transmission gear 81 while being driven by the drive transmission gear 81. Furthermore, as will be described later in Examples 22 and 23, the distance (radius) R63e from the rotation axis L1 to the outer diameter of the cylindrical portion 63e may be configured to be able to become smaller, at least temporarily, than the tip circle radius Rt63ct of the first gear portion 63c or the tip circle radius Rt63d of the second gear portion 63d so that the drive side flange 63 and the drive transmission gear 81 can mesh to transmit the driving force.

[0072] Here, the relationship between these dimensions is shown using the diameters of the first gear portion 63c, the second gear portion 63d, and the cylindrical portion 63e. However, it is obvious that the same relationship applies even if the diameters are replaced with radii. The shape of the cylindrical portion 63e does not have to be a cylindrical shape centered on the rotation axis L1. For example, various shapes are possible, such as a polygonal prism shape or a shape that is not symmetrical with respect to the rotation axis L1. In this case, when the drive-side flange 63 rotates, the diameter of a circle drawn as a rotation locus by the point of the intermediate portion 63e farthest from the rotation axis L1 is the above-mentioned maximum diameter D63e, and the radius of that circle is the maximum value of the radius R63e.

[0073] By providing the cylindrical portion 63e, the second gear portion 63d can be disposed at a position away from the drum 62 (more downstream in the direction J) so as not to come into contact with the first gear portion 81c. Similarly, the first gear portion 63c can be disposed at a position closer to the drum 62 (more downstream in the direction H) so as not to come into contact with the second main body gear portion 81d. In other words, by providing the cylindrical portion 63e, a gap g is formed between the first gear portion 81c and the second gear portion 63d in the direction of the rotation axis L1. This makes it possible to prevent the first gear portion 63c from coming into contact with the second main body gear portion 81d and the second gear portion 63d from coming into contact with the first main body gear portion 81c in the direction of the rotation axis L1 when the cartridge B is attached to the apparatus main body A. Furthermore, when the drive transmission gear 81 is driven to move to a balanced position, the first main body gear portion 81c can be prevented from contacting the second gear portion 63d, and the second main body gear portion 81d can be prevented from contacting the first gear portion 63c. The width of the cylindrical portion 63e in the direction of the rotation axis L1 will be described in detail below.

[0074] <Drive transmission to the developing roller> 15 is a diagram showing the drive force transmission configuration from the drive-side flange 63 to the developing roller 32. The developing roller 32 is fixed to the developing roller shaft 31, and a developing roller gear 30 is provided at one end of the driving side of the developing roller shaft 31 so as to be movable in the direction of the rotation axis of the developing roller shaft 31. The developing roller gear 30 is rotatable integrally with the developing roller shaft 31 and the developing roller 32. In other words, the developing roller gear 30 is provided so as to be able to transmit drive force to the developing roller shaft 31 and the developing roller 32. The developing roller gear 30 meshes with a first gear portion 63c of the drive-side flange 63 to transmit drive force.

[0075] The developing roller gear 30 may be configured to mesh with the second gear portion 63d to transmit the driving force. However, by configuring the developing roller gear 30 to mesh with the first gear portion 63c, the length of the developing roller shaft 31 in the rotational axis direction can be made shorter than in a configuration in which the developing roller gear 30 meshes with the second gear portion 63d.

[0076] <Drive transmission operation> Next, the meshing operation between the drive transmission gear 81 and the drive side flange 63 will be described in order from the mounting of the cartridge B with reference to Figures 16, 17, 19, 20 and 21.

[0077] FIG. 16(a) is a schematic diagram of the drive transmission gear 81 and the drive side flange 63 viewed along their rotational axis direction. FIG. 16(b) is a cross-sectional view of the drive transmission gear 81 taken along the cutting line AF-AF. In FIG. 16(b) and subsequent figures, the hatched areas in the figure represent cross sections of the gear peaks, and the areas between the hatched areas represent the gear valleys. FIG. 16(c) is a cross-sectional view of the drive side flange 63 taken along the cutting line AF-AF. FIG. 16(d) is a cross-sectional view of the drive transmission gear 81 taken along the cutting line AF-AF before the cartridge is installed. FIG. 16(e) is a cross-sectional view of the drive transmission gear 81 and the drive side flange 63 taken along the cutting line AF-AF after the cartridge B has been installed and before the cartridge is driven.

[0078] Figure 17 is a cross-sectional view taken along the cutting plane AF-AF tangent to the meshing pitch circle of the drive transmission gear 81 and the drive side flange 63 immediately after the start of driving, and shows the state over time in the order of Figure 17(a), Figure 17(b), Figure 17(c), and Figure 17(d).

[0079] 19(a), 19(b), and 19(c) are views of the drive transmission gear 81 and the drive-side flange 63 viewed along the H direction.

[0080] Figure 21(a) is a view of the drive transmission gear 81 and the drive-side flange 63 viewed in a direction perpendicular to the rotation axis. Figure 21(b) is a cross-sectional view of the first main body gear portion 81c taken along the line AD-AD during driving. Figure 21(c) is a cross-sectional view of the second main body gear portion 81d taken along the line AD-AD during driving.

[0081] <Engagement when Cartridge B is installed> 16(d), before the cartridge B is attached, the drive transmission gear 81 is held by the biasing force F1 of the compression spring 85, with the other end 81e of the drive transmission gear 81 abutting against the abutment surface 84b of the main frame 84. By configuring the drive transmission gear 81 to be held in abutment against the abutment surface 84b in this manner, the initial position of the drive transmission gear 81 in the direction of its rotation axis can be kept constant, and meshing with the drive-side flange 63 can be stabilized.

[0082] As the cartridge B is mounted into the apparatus main assembly A in the mounting direction M (M direction), the drive-side flange 63 engages with the drive transmission gear 81, as shown in FIG. 19(a). The force required to rotate the drive-side flange 63 is greater than the force required to rotate the drive transmission gear 81. Therefore, movement of the drive-side flange 63 in the M direction rotates the drive transmission gear 81 in the I direction (clockwise). At this time, as shown in FIG. 16(e), the first main body gear portion 81c or the second main body gear portion 81d of the drive transmission gear 81 comes into contact with the first gear portion 63c or the second gear portion 63d of the drive-side flange 63 and is pressed in the M direction. A thrust force F3 in the H direction acts on the drive transmission gear 81. However, the other end 81e of the drive transmission gear 81 abuts against the abutment surface 84b of the main frame 84 and receives a reaction force F4, preventing the drive transmission gear 81 from moving in the H direction.

[0083] <Operation after drive starts> Next, a case where the drive-side flange 63 is driven to perform an initial operation, a preparatory operation for image formation, or the like will be described. As shown in FIG. 19(b), the drive transmission gear 81 is rotated in the I direction by a motor (not shown) of the apparatus main body A. This causes the drive-side flange 63 to rotate in the K direction. Immediately after the drive transmission gear 81 starts to rotate in the I direction, as shown in FIG. 17(a), the second main body gear portion 81d of the drive transmission gear 81 first engages with the second gear portion 63d of the drive-side flange 63 to transmit the driving force. Then, the second main body gear portion 81d generates a thrust force in the H direction on the second gear portion 63d. However, the drive-side flange 63 is restricted from moving in the H direction by the rib 71p, and receives a reaction force in the J direction corresponding to the thrust force in the H direction. Therefore, the second main body gear portion 81d receives a thrust force F5 in the J direction due to the reaction force from the second gear portion 63d. This thrust force F5 causes the drive transmission gear 81 to move in the J direction.

[0084] As the drive transmission gear 81 continues to rotate and moves in the J direction, the first gear portion 63c also meshes with the first main body gear portion 81c, and a thrust force F6 is generated in the first main body gear portion 81c, as shown in Figure 17(b). The thrust force F6 is a thrust force in the J direction, the same as the thrust force F7 that the second main body gear portion 81d received when it meshed with the second gear portion 63d. This causes the drive transmission gear 81 to move further in the J direction.

[0085] As the drive transmission gear 81 further rotates and moves in the J direction, the second main body gear portion 81d eventually disengages from the second gear portion 63d, as shown in Figure 17(c). Meanwhile, the first gear portion 81c remains engaged with the first gear portion 63c, and a thrust force F8 acts on the first gear portion 81c in the J direction. At this time, the drive transmission gear 81 rotates the drive-side flange 63 solely by the engagement between the first main body gear portion 81c and the first gear portion 63c. In other words, the tooth surface 81c1 on the downstream side in the I direction of the first main body gear portion 81c and the tooth surface 63c1 on the upstream side in the I direction of the first gear portion 63c are in contact with each other.

[0086] This is because the twist angle α2 of the second main body gear portion 81d of the drive transmission gear 81 is larger than the twist angle α1 of the first main body gear portion 81c (α2 > α1). Specifically, it will be described below with reference to FIGS. 21(b) and 21(c). Assume that the drive transmission gear 81 moves a movement amount LL in the J direction by receiving a thrust force through engagement with the drive-side flange 63. In FIGS. 21(b) and 21(c), the first main body gear portion 81c and the second main body gear portion 81d are shown with solid lines before movement and dashed lines after movement. The movement amounts in the rotational direction of the first main body gear portion 81c and the second main body gear portion 81d associated with this movement can be expressed as LL / tanα1 and LL / tanα2, respectively. Based on the relationship between the twist angles α1 and α2, the movement amount LL / tanα2 in the rotational direction of the second main body gear portion 81d is larger than the movement amount LL / tanα1 in the rotational direction of the first main body gear portion 81c (LL / tanα1 < LL / tanα2). Thus, the movement amount in the rotational direction corresponding to the movement amount LL in the J direction is larger for the second main body gear portion 81d than for the first main body gear portion 81c. For this reason, even if the first main body gear portion 81c and the first gear portion 63c are engaged, the second main body gear portion 81d will separate from the second gear portion 63d.

[0087] When the rotation continues and the drive transmission gear 81 moves toward the drive side J, as shown in FIG. 17(d), finally, the tooth surface 81d2 on the upstream side of the second main body gear portion 81d in the I direction contacts the tooth surface (contact portion) 63d2 on the downstream side of the second gear portion 63d in the I direction. Note that the surface 81c1 of the first main body gear portion 81c and the surface 63c1 of the first gear portion 63c maintain contact. That is, in this state, the first main body gear portion 81c of the drive transmission gear 81 presses the tooth surface (contact portion) 63c1 with the tooth surface 81c1 to rotate the drive-side flange 63, and the tooth surface 81d2 of the second main body gear portion 81d of the drive transmission gear 81 abuts against the tooth surface 63d2 and is sandwiched by the drive-side flange 63. Then, the movement in the direction of the rotation axis L1 of the drive transmission gear 81 stops. The position in the direction of the rotation axis L1 at this time is defined as the equilibrium position. A state where the drive transmission gear 81 rotates at the equilibrium position and transmits drive to the drive-side flange 63 will be described.

[0088] In the balanced state, the drive transmission gear 81 is subjected to the following forces F9, F10, and F1 in the direction of the rotation axis L1. Force F9 is a thrust force in the J direction that the first main gear portion 81c receives as a result of meshing with the first gear portion 63c. Force F1 is a thrust force in the H direction that the second main gear portion 81d receives as a result of meshing with the second gear portion 63d. Force F1 is the biasing force of the compression spring 85. In addition, the drive-side flange 63 receives a force from the drive transmission gear 81 and is positioned in the direction of the rotation axis L1 by the side wall 71m or the rib 71p, and a reaction force F11 that balances the force received from the drive transmission gear 81 is generated. Note that Figure 17(d) shows the case where the drive transmission gear 81 is positioned by abutting against the side wall 71m. In the balanced state, ignoring friction, forces F9, F10, F1, and F11 are balanced, and the drive transmission gear 81 and the drive side flange 63 are each positioned in the direction of the rotation axis L1.

[0089] Furthermore, in the K direction (rotational direction), the drive-side flange 63 is sandwiched (contacted) between (and receives) the following forces: That is, the tooth surface (contact portion) 63c1 of the first gear portion 63c comes into contact with the first main gear portion 81c, which is disposed upstream in the K direction (first circumferential direction), and receives a driving force FD as a force component in a direction that rotates the drive-side flange 63 in the K direction (predetermined direction). At the same time, the tooth surface (contact portion) 63d2 of the second gear portion 63d comes into contact with the second main gear portion 81d, which is disposed downstream in the K direction (first circumferential direction), and receives a restricting force (braking force) FB as a force component in a direction that suppresses (restricts) the rotation of the drive-side flange 63 in the K direction. Therefore, it can be said that the first gear portion 63c is a driving force receiving portion that receives the driving force FD, and the second gear portion 63d is a restricting force receiving portion that receives the restricting force FB. The driving force FD is greater than the restraining force FB.

[0090] Here, the second gear portion 63d is integral with the first gear portion 63c in terms of the rotational direction, and is therefore configured to be unable to rotate relative to the first gear portion 63c in the direction opposite to the K direction. Strictly speaking, because the drive-side flange 63 is made of resin and deformation of the teeth and members occurs, the second gear portion 63d, which receives the restricting force FB, rotates slightly relative to the first gear portion 63c in the direction opposite to the K direction (reverse), and then stops rotating and becomes fixed. Therefore, the restricting force FB received by the second gear portion 63d acts (is transmitted) to the first gear portion 63c. Using the same principle, the driving force FD received by the first gear portion 63d acts (is transmitted) to the second gear portion 63d.

[0091] In this way, when the first gear portion 63c receives the driving force FD and the second gear portion 63d receives the restricting force FB, there is no backlash (backlash) in the rotational direction (direction I) between the drive-side flange 63 and the drive transmission gear 81, i.e., it is in a backlash-less state. In this way, the drive-side flange 63 is driven to rotate in the direction K while maintaining the backlash-less state. While the gears are engaged and transmitting drive power in a backlash-less state, drive power can be transmitted with high rotational accuracy.

[0092] Furthermore, the width (tooth width) W63c of the first helical teeth (first protrusions) 63ct in the direction of the rotation axis L1 is larger than the width (tooth width) W63d of the second helical teeth (second protrusions) 63dt in the direction of the rotation axis L1. In other words, the second gear portion 63d has second helical teeth (second protrusions) 63dt that are narrower than the first helical teeth 63ct, which have the widest width (tooth width) in the direction of the rotation axis L1 of the first gear portion 63c.

[0093] If the second main body gear portion 81d and the second gear portion 63d are not in contact at the start of drive, and the first main body gear portion 81c and the first gear portion 63c are in contact, drive will start from the state shown in Figure 17(c) without passing through the states shown in Figures 17(a) and 17(b). Then, based on the same principle as described above, the balanced state shown in Figure 17(d) is reached. That is, from the state shown in Figure 17(c), the drive transmission gear 81 moves in the J direction due to thrust force F8, and transitions to the balanced state shown in Figure 17(d).

[0094] <Disengagement when removing cartridge B> Next, the disengagement operation between the drive transmission gear 81 and the drive-side flange 63 when removing the cartridge B after driving has finished will be described with reference to Figures 18, 19, and 20. Figure 18 is a cross-sectional view taken along the cutting plane AF-AF tangent to the meshing pitch circle of the drive transmission gear 81 and the drive-side flange 63 when removing the cartridge B after driving has finished, and shows the states as time passes in the order of Figures 18(a) and 18(b). Figure 20 is a schematic view of the drive transmission gear 81 and the drive-side flange 63 as viewed along the H direction.

[0095] As shown in FIG. 19(c), the cartridge B is removed from the apparatus main assembly A by moving it in the removal direction N (N direction). The N direction is the opposite direction to the M direction. As mentioned above, the force required to rotate the drive side flange 63 is greater than the force required to rotate the drive transmission gear 81. Therefore, the movement of the drive side flange 63 in the N direction causes the drive transmission gear 81 to rotate in the K direction (counterclockwise). At this time, as shown in FIG. 18(a), when the drive side flange 63 moves in the N direction, the first gear portion 63c presses the first main body gear portion 81c. Also, FIG. 20 shows the positional relationship between the drive side flange 63 and the drive transmission gear 81 moving in the N direction, with the solid line indicating the position before the movement in the N direction and the dashed line indicating the position after the movement. The distance between the rotation center (rotation axis) L1 of the drive side flange 63 and the rotation center (rotation axis) L2 of the drive transmission gear 81 changes from distance LA to distance LB as the drive side flange 63 moves in the N direction (LA <LB)。

[0096] As a result, the meshing position of the teeth of the first gear portion 63c and the first main body gear portion 81c gradually shifts to the tooth tips. Therefore, as shown in FIG. 18(b), the backlash in the meshing of the teeth in the rotational direction increases, and the gap AL between the surface 63d2 of the second gear portion 63d and the tooth surface 81d2 of the second main body gear portion 81d increases. When the gap AL is generated between the tooth surfaces, no force from the second gear portion 63d acts on the drive transmission gear 81, and instead, a thrust force F16 in the J direction is applied by the meshing of the first main body gear portion 81c and the first gear portion 63c. As a result, when the cartridge B is removed, the drive transmission gear 81 gradually moves in the J direction while rotating in the K direction, and eventually the meshing between the first gear portion 63c and the first main body gear portion 81c is released. This releases the meshing between the drive-side flange 63 and the drive transmission gear 81.

[0097] <Twist angle setting> Next, preferred helix angles of the first gear portion 63c and the second gear portion 63d will be described with reference to Figure 46. Figures 46(a) and 46(b) are cross-sectional views taken along the cutting plane AF-AF tangent to the meshing pitch circle of the second gear portion 63d, the drive transmission gear 81 of the second main body gear portion 81d, and the drive-side flange 63.

[0098] As described above, the setting of the torsion angle α1 of the first gear portion 63c and the torsion angle α2 of the second gear portion 63d when the first gear portion 63c is the gear portion that receives the driving force FD and the second gear portion 63d is the gear portion that receives the restricting force FB will be described. First, as a premise, because the first gear portion 63c is the gear portion that receives the driving force FD and the second gear portion 63d is the gear portion that receives the restricting force FB, the torsion angle α2 is larger than the torsion angle α1 (α2 > α1). If the torsion angle α2 were smaller than the torsion angle α1, drive power could not be transmitted in a backlash-free state. In other words, the thrust force applied by the first gear portion 63c to the first main gear portion 81c and the thrust force applied by the second gear portion 63d to the second main gear portion 81d would not be balanced, and the position of the drive transmission gear 81 in the direction of the rotation axis L1 would not be determined at a balanced position.

[0099] The helix angle α1 of the first gear portion 63c of the drive-side flange 63 is preferably 10° or more (α1≧10°), more preferably 15° or more (α1≧15°), and even more preferably 20° or more (α1≧20°). This is because, generally, for a given face width (the width of the gear teeth in the direction of the rotation axis L1), the larger the helix angle, the higher the meshing ratio and the more improved the rotational accuracy. Furthermore, the helix angle α1 is preferably 40° or less (α1≦40°), and more preferably 35° or less (α1≦35°). This is because a larger helix angle generally results in poor moldability in a mold.

[0100] On the other hand, the helix angle α2 of the second gear portion 63d of the drum gear 63 is preferably 40° or less (α2≦40°), and more preferably 35° or less (α2≦35°). This is because a larger helix angle generally leads to poor moldability in a mold. Furthermore, the helix angle α2 of the second gear portion 63d of the drum gear is preferably 20° or more (α2≧20°), and more preferably 25° or more (α2≧25°). This is because, as shown in FIGS. 46(a) and 46(b), the larger the helix angle α2, the larger the width E of the contact surface with the second main gear portion 81d in the rotational direction (direction K). In this embodiment, the helix angle α2 is set to 35°.

[0101] If the width E is small, when the second gear portion 63d receives the thrust force F9 (see FIG. 17(d)) ​​received by the first gear portion 63c, the tooth surface of the second gear portion 63d is deformed, and the second main body gear portion 81d is moved like a wedge, making the positioning in the direction of the rotation axis L1 unstable. For this reason, a certain degree of width E needs to be secured in order to reliably receive the thrust force F9 and position the drive transmission gear 81 in the direction of the rotation axis L1.

[0102] Considering the above, the twist angle α1 is preferably 10° or more and 40° or less (15°≦α1≦40°), more preferably 15° or more and 40° or less (15°≦α1≦40°), and even more preferably 20° or more and 35° or less (20°≦α1≦35°). Furthermore, the twist angle α2 is preferably 20° or more and 40° or less (20°≦α2≦40°), and more preferably 25° or more and 35° or less (25°≦α2≦35°). In this embodiment, the twist angle α1 is set to 20°, and the twist angle α2 is set to 35°, satisfying the above conditions.

[0103] <Width of cylindrical portion 63e> Next, the width (length) of the cylindrical portion 63e in the direction of the rotation axis L1 will be described. Figure 47(a) is a schematic diagram of the driving side flange 63 and the drive transmission gear 81 when the cartridge B is attached, viewed from a direction perpendicular to the rotation axis L1. Figure 47(b) is a schematic diagram of the driving side flange 63 and the drive transmission gear 81 during driving, viewed from a direction perpendicular to the rotation axis L1.

[0104] As described above, the provision of the cylindrical portion 63e can prevent the first gear portion 63c from contacting the second main body gear portion 81d and the second gear portion 63d from contacting the first main body gear portion 81c in the direction of the rotation axis L1. Furthermore, the provision of the cylindrical portion 63e can prevent the first main body gear portion 81c from contacting the second gear portion 63d and the second main body gear portion 81d from contacting the first gear portion 63c when the drive transmission gear 81 is driven and moves to a balanced position. In other words, the provision of the cylindrical portion 63e forms a gap g between the first gear portion 81c and the second gear portion 63d in the direction of the rotation axis L1. Therefore, in the following description, the width (length) of the cylindrical portion 63e in the direction of the rotation axis L1 is synonymous with the width (length) of the gap g in the direction of the rotation axis L1.

[0105] The above-mentioned contact can occur in the following two situations. The first situation is when, as shown in Figure 47(a), when the cartridge B is attached to the apparatus main body A, the other end 81e of the drive transmission gear 81 abuts against the abutment surface 84b of the main frame 84 and is held there. The second situation is when, as shown in Figure 47(b), the drive transmission gear 81 is driven and moves toward the balanced position.

[0106] The positions of the first gear portion 63c and the second gear portion 63d of the drive-side flange 63, the positions of the first main body gear portion 81c and the second main body gear portion 81d of the drive transmission gear 81, and the balance position may vary due to the influence of the following factors: (1) tolerances in the direction of the rotational axis L1 of related parts such as the drive-side flange 63, the drive transmission gear 81, and the cleaning unit frame (drum frame) 60a, (2) tolerances related to the distance between the rotational axis L1 of the drive-side flange 63 and the rotational axis L2 of the drive transmission gear 81, (3) tolerances in the phase of the teeth of the first gear portion 63c and the second gear portion 63d of the drive-side flange 63, (4) tolerances in the phase of the teeth of the first main body gear portion 81c and the second main body gear portion 81d of the drive transmission gear 81, and (5) deformation of the teeth due to the maximum drive load and thermal expansion and contraction of the drive-side flange 63 and the drive transmission gear 81. Taking these factors into consideration, the width (length) We of the cylindrical portion 63e (or the gap g) in the direction of the rotation axis L1 is set.

[0107] Specifically, the width We is preferably set to satisfy the following formula B1, where Wc is the width (tooth width, length) of the teeth of the first gear portion 63c in the direction of the rotation axis L1. We≧Wc / 5...(Formula B1)

[0108] Furthermore, since the greater the width We, the greater the width of the cartridge B in the direction of the rotation axis L1, the width We should not be set to be larger than necessary in order to reduce the size of the cartridge B and the apparatus main body A. In light of this, it is more preferable to set the width We so as to satisfy the following formula B2. We≦Wc...(Formula B2)

[0109] In this embodiment, Wc=8.6 mm and We=2.3 mm are set, which satisfies the above formulas B1 and B2. If the face width Wc of the first gear portion 63c is not constant, the face width Wc1 of the widest tooth is set to be the face width Wc.

[0110] Furthermore, as is clear from Figures 13(b), 14, and 47, when the width (tooth width, length) of the teeth of the second gear portion 63c in the direction of the rotation axis L1 is defined as Wd, it is preferable to set the width We so as to satisfy the following formula B3, We≦Wd (Equation B3)

[0111] <About rotation accuracy> The reason why rotation accuracy improves in a backlash-free state will be explained below using Figures 22 and 49. Figure 22(a) is a view of the drive transmission gear 81 and the drive-side flange 63 viewed in a direction perpendicular to the rotation axis direction. Figure 22(b) is a partial cross-sectional view of the meshing portion of general helical gears 51 and 53 as a comparative example. Figure 22(c) is a partial cross-sectional view taken along the cut plane AD-AD tangent to the meshing pitch circle of the drive transmission gear 81 and the drive-side flange 63. Figure 22(d) is a partial perspective view of the helical gear 51. Figure 22(e) is a partial perspective view of the drive transmission gear 81. Figure 49 is a graph comparing drive transmission error when the drive-side flange 63 and the helical gear 53 are misaligned.

[0112] As shown in Figure 22(b), due to molding accuracy, backlash, or deformation of the shaft, the tooth flanks of the driving and driven helical gears may not be parallel in the tooth trace direction when they mesh. This condition is commonly referred to as misalignment. When the misalignment of a typical helical gear (drive side) 51 and a helical gear (driven side) 53 is β°, the helical gears 51 and 53 mesh only at one end of their tooth flanks in the axial direction, significantly reducing the meshing ratio compared to when they are not misaligned. This significantly reduces the rotational accuracy during drive transmission. Figure 22(d) shows the meshing area of ​​the tooth flank of the helical gear 51 with the helical gear 53 when they are misaligned. The width of this area is referred to as width LP.

[0113] On the other hand, as shown in FIG. 22(c), the drive-side flange 63 rotates while sandwiching the first main body gear portion 81c and the second main body gear portion 81d of the drive transmission gear 81 between the first gear portion 63c and the second gear portion 63d of the drive-side flange 63. This generates a sandwiching force FC (i.e., a brake on the rotational drive) acting on the second main body gear portion 81d. The reaction of this sandwiching force FC is added to the force applied to the tooth surface of the first main body gear portion 81c, which presses the first gear portion 63c in the I direction, resulting in a force FB. On the other hand, when the same load torque is driven, the force FA applied to the tooth surface of the conventional helical gear 51 does not generate any excess load. Therefore, the force FB applied to the tooth surface of the first main body gear portion 81c of this embodiment is greater than the force FA applied to the tooth surface of the helical gear 51. Figure 22(e) shows the area where the tooth surface of the first main gear portion 81c of the drive transmission gear 81 meshes with the first gear portion 63 of the drive-side flange 63 when misaligned, and the width of this area is width LQ. Because force FB is greater than force FA, when width LP in Figure 22(d) is compared with width LQ in Figure 22(e), width LQ is greater than width LP. For this reason, when misalignment occurs, the reduction in the overlapping meshing rate of the first main gear portion 81c and the first gear portion 63c is smaller than that of the helical gears 51, 53.

[0114] Figure 49 is a graph showing the measurement results of the drive transmission error of the driven helical gear 53 and the drive flange 63 versus the amount of misalignment when using conventional helical gears 51 and 53 and when using the drive transmission gear 81 and drive flange 63 of this embodiment. The helical gears 51 and 53 and the drive transmission gear 81 and drive flange 63 were identical in terms of gear specifications (number of teeth, axial backlash of 0.15 mm, load torque of 0.25 N m, rotational speed of 270 rpm, etc.), and the shafts and gears were fitted with no play. Here, the drive transmission error (%) refers to the percentage deviation of the experimental rotational pitch from the ideal rotational pitch at the gear meshing period. For example, if the ideal rotational pitch is 0.7258 mm and the experimental deviation from the ideal rotational pitch is 0.00036 mm, the drive transmission error is 0.05% (= 0.00036 / 0.7258 × 100). Furthermore, the amount of misalignment (°) is the angle between the meshed gears when the axes are parallel, which is defined as 0°, and the angle β (see Figures 22(b) and 22(c)) between the teeth of the driven gear is misaligned. As shown in this graph, when misalignment occurs, the deterioration of rotational accuracy of the drive-side flange 63 of this embodiment is suppressed more than that of a general helical gear 53. Therefore, it can be said that the drive transmission configuration using the drive transmission gear 81 and drive-side flange 63 of this embodiment is more resistant to misalignment than a drive transmission configuration using a general helical gear.

[0115] <About wear of drive transmission gears> Next, wear of the drive transmission gear 81 and the helical gear 101 will be described below with reference to FIG. 24. FIG. 24(a) is a schematic diagram of a drive transmission configuration using a conventional helical gear. FIG. 24(b) is a schematic diagram of the drive transmission configuration of this embodiment. As shown in FIG. 24(a), when the helical gear 101 is driven to rotate, the helical gear 101 receives a thrust force (axial force) FD due to the meshing force. This causes the helical gear 101 to move in the H direction toward the non-drive side, and the end face 101a of the helical gear 101 and the abutment surface 184b of the main frame 84 come into contact and slide, causing wear. 24(b), the position of the drive transmission gear 81 in this embodiment in the direction of the rotation axis L1 is determined by the drive-side flange 63 and the spring 85 (not shown) during driving, so a gap AA is formed between the H-direction end face 81e and the J-direction end face 81f of the drive transmission gear 81 and the main frame 84 and the second drive-side side plate 83, preventing sliding. This reduces wear on the two end faces 81e, 81f of the drive transmission gear 81, the main frame 84, and the second drive-side side plate 83, thereby improving durability.

[0116] <Comparison with conventional coupling drive> Next, a comparison with a configuration in which a drum is driven by a conventional coupling will be described using Figures 26 and 27. Figure 26(a) is a cross-sectional view of the drive transmission section of a conventional coupling drive, the cross-section including the rotation axis of the coupling. Figure 26(b) is a cross-sectional view of the drive transmission section of this embodiment, the cross-section including the rotation axis (L1) of the drive-side flange 63 and the rotation axis of the drive transmission gear 81. Figure 27 is a graph showing the amount of deformation of the coupling drive and the drive transmission gear.

[0117] As shown in Figure 26(a), in conventional coupling drive, a drive-side flange 263 equipped with a convex coupling 263a in the shape of a twisted polygonal pillar is attached to the end of a cartridge drum 62. The drum flange 263 has a support portion 263b that is a cylindrical portion with a diameter smaller than that of the drum 62. The device main body has a drive transmission gear 281 equipped with a concave coupling 281a into which the coupling 263a is inserted and engaged.

[0118] The coupling 263a is provided at the end of the drive-side flange 263 in the direction of the rotation axis. Therefore, the amount of torsion of the drive-side flange 263 during coupling drive is greater than the amount of torsion of the drive-side flange 63 during gear drive of this embodiment, as shown in Figure 26(b). Figure 27 shows the simulation results of the amount of deformation of the drive members (drum flange 263, drive-side flange 63) in the rotation direction, with gear drive (driving by the drive-side flange 63) being smaller than coupling drive (driving by the drum flange 263). Here, we will explain the amount of deformation of the drive members in the rotation direction. This amount of deformation is the amount of rotational displacement of the drive transmission point to the drum 62 when the drum 62 side of the drum coupling 263 and drive-side flange 63 are fixed and the same static load torque of 0.25 N·m is applied to the engagement portion with the drive input member 281 or the meshing portion with the drive transmission gear 81. The drive transmission point is a point fixed to the drum 62. The amount of displacement is then converted into the amount of positional deviation relative to the case where there is no twist at a given point on the surface of the drum 62. Due to this difference in the amount of deformation of the drive member, the fluctuation in the amount of deformation of the drive member when a load torque fluctuation occurs in cartridge B is smaller in gear drive than in coupling drive, and the fluctuation in the rotation speed of the drum 62 due to the fluctuation in the amount of deformation is smaller. In other words, it is possible to reduce image density unevenness in the direction of rotation of the drum 62 when a load torque fluctuation occurs in cartridge B (which occurs due to variations in the pitch in the sub-scanning direction between scanning lines formed when the surface of the drum 62 is scanned with laser light L (pitch unevenness)). As such, the drive transmission configuration of the drive-side flange 63 and drive transmission gear 81 of the above-described embodiment can reduce the deterioration in rotation accuracy of the drum 62 due to load torque fluctuation compared to the conventional coupling drive configuration.

[0119] Also, from another perspective, compared with the conventional coupling drive, in the case of the conventional coupling drive, it is necessary to provide a retraction mechanism for moving the coupling 263a on the main body side back and forth in the direction of the rotation axis in order to mount and remove the cartridge B.

[0120] Next, this retraction mechanism will be described with reference to Figure 28. Figure 28(a) is a cross-sectional view of the retraction mechanism taken along a plane including the rotation axis of drum 62. Figure 28(b) is a schematic cross-sectional view of an image forming apparatus equipped with the retraction mechanism. Figures 28(c) and 28(d) are cross-sectional views of the drive transmission gear 281 and the retraction mechanism, and the cross-sections are cross-sectional views including the rotation axis of drive transmission gear 281.

[0121] The main body of the coupling-driven image forming apparatus is provided with a retraction mechanism consisting of a link 210, a cylindrical cam 212, and a compression spring 214. One end of the link 210 is connected to an opening / closing door 211 of the main body A of the apparatus. The other end of the link 210 is connected to a cylindrical cam 212 rotatably disposed coaxially with the drive input member 281 between the drive input member 281 and a side wall 213. As shown in FIG. 28(a), the cylindrical cam 212 has an inclined surface 212d, a convex surface 212c, and a concave surface 212e on one end surface in the axial direction, which have height differences in the rotational direction. Furthermore, the side wall 213 has an inclined surface 213e, a convex surface 213f, and a concave surface 213g at locations facing the inclined surface 212d, the convex surface 212c, and the concave surface 212e, respectively. As shown in FIG. 28(d), the drive transmission gear 281 is biased in the H direction by a compression spring 214.

[0122] As shown in FIG. 28(b), opening the door 211 rotates the cylindrical cam 212 in direction I via the link 210, and the cylindrical cam 212 comes into contact with the convex surfaces 212c and 213f provided on the side wall 213, moving the cylindrical cam 212 in direction J. This movement of the cylindrical cam 212 in direction J causes the cylindrical cam 212 to move the drive input member 281 in direction J against the biasing force of the compression spring 214, as shown in FIG. 28(c). This causes the drive input member 281 to move in a direction away from the drum flange 263 (see FIG. 26(a)), and disengages the coupling 281a from the coupling 263a (see FIG. 26(a)). As a result, it becomes possible to remove the cartridge B.

[0123] 28(b), by the closing operation of door 211, cylindrical cam 212 rotates in the reverse direction of direction I via link 210 while inclined surfaces 212d, 213e provided on cylindrical cam 212 and side wall 213 abut against each other. During this rotation, cylindrical cam 212, side wall 213, and drive input member 281 no longer abut against each other in the direction of the rotation axis, and as shown in FIG. 28(d), drive input member 281 becomes movable in direction H due to the biasing force of compression spring 214. As a result, drive input member 281 moves in a direction approaching drum flange 263 (see FIG. 26(a)), and coupling 281a and coupling 263a (see FIG. 26(a)) become engageable with each other.

[0124] As described above, in the case of conventional coupling drive, a retraction mechanism is required as explained above, which may increase the size and cost of the apparatus body. However, in the case of gear drive as in this embodiment, cartridge B can be mounted and removed without providing such a retraction mechanism.

[0125] <Variation 1> Next, Modification 1 will be described. In the above-described embodiment, the first main body gear portion 81c and the second main body gear portion 81d of the drive transmission gear 81 have the same number of teeth. However, this does not necessarily have to be the case. However, the reduction ratio between the first main body gear portion 81c of the drive transmission gear 81 and the first gear portion 63c of the drive-side flange 63 and the reduction ratio between the second main body gear portion 81d of the drive transmission gear 81 and the second gear portion 63d of the drive-side flange 63 must be the same. For example, if the first gear portion 81d of the drive transmission gear has 20 teeth and the first gear portion of the drum gear has 30 teeth, resulting in a reduction ratio of 2:3, then if the second main body gear portion 81d of the drive transmission gear has 40 teeth and the second gear portion 63d of the drive-side flange 63 has 60 teeth, the reduction ratio will be the same, 2:3. In this case, too, the gear of the drive transmission gear 81 can be sandwiched between the first gear portion 63c and the second gear portion 63d of the drive-side flange 63, thereby achieving a backlash-free state in the rotational direction.

[0126] <Variation 2> Next, Modification 2 will be described. In this modification, the first gear portion 181c and the second gear portion 181d of the drive transmission gear 181 have different numbers of teeth, and the number of teeth on one side is not an integer multiple of the number of teeth on the other side. The first gear portion 163c and the second gear portion 163d of the drive side flange 163 also have different numbers of teeth, and the number of teeth on one side is not an integer multiple of the number of teeth on the other side. These are the points where this modification differs from the previously described embodiment, and apart from these differences and the associated configuration, the configuration of this modification is the same as the configuration of the previously described embodiment, so a description thereof will be omitted.

[0127] In this modified example, as in the previous embodiment, it is possible to achieve a backlash-free state in the rotational direction. However, due to the setting of the number of teeth as described above, this modified example has a configuration in which the meshing phase of the drive transmission gear 181 with the drive side flange 163 is not unique. In a configuration in which the meshing phase is not unique, the axially positioned (balanced) position of the drive transmission gear 181 will be described using FIG. 25 . FIG. 25(a) is a schematic diagram of the drive transmission configuration using the drive transmission gear 81 of the previous embodiment. FIG. 25(b) is an explanatory diagram of the drive transmission section using the drive transmission gear 181 and drive side flange 163 of the modified example. FIG. 25(c) and FIG. 25(d) show the drive transmission gear 181 in the balanced position after being driven.

[0128] 25(c) and 25(d), the drive transmission gear 181 and the drive-side flange 163 mesh together, but the meshing manner at the meshing portion is different. Specifically, in FIG. 25(c), at the meshing portion between the drive-side flange 163 and the drive transmission gear 181, the tooth crests of the first gear portion 181c of the drive transmission gear 181 are in phase with the tooth crests of the second gear portion 181d, and the tooth crests of the first gear portion 163c of the drive-side flange 163 are in phase with the tooth crests of the second gear portion 163d. In FIG. 25(d), the tooth crests of the first gear portion 181c of the drive transmission gear 181 are in phase with the tooth crests of the second gear portion 181d at the meshing portion, and the tooth crests of the first gear portion 163c of the drive-side flange 163 are in phase with the tooth troughs of the second gear portion 163d.

[0129] When the first gear portion 181c and the second gear portion 181d of the drive transmission gear 181 have different numbers of teeth, the phases of the tooth crests of the first gear portion 181c and the second gear portion 181d differ depending on the phase of the rotational direction of the gears. For example, depending on the phase of the rotational direction of the gears, there is a position Q1 where the phase of the tooth crests 181cs of the first gear portion and the phase of the tooth crests 181ds of the second gear portion are aligned, and there is also a position Q2 where the phase of the tooth crests 181cs of the first gear portion and the phase of the tooth valleys 181dv of the second gear portion are aligned. This also applies to the relationship between the first gear portion 163c and the second gear portion 163d of the drum gear 163. As a result, as shown in Figures 25(c) and 25(d), the axial balance position of the drive transmission gear 181 relative to the drive-side flange 163 differs depending on the phase of the initial (before drive) meshing of the drive transmission gear 181 and the drive-side flange 163 in the rotational direction. Figure 25(c) shows the case where the balancing position of the drive transmission gear 181 is at the most downstream side in the H direction, and Figure 25(d) shows the case where the balancing position of the drive transmission gear 181 is at the most downstream side in the J direction. The amount of change in the balancing position can be expressed, for example, by the amount of deviation of the boundary line between the first gear portion 181c and the second gear portion 181d of the drive transmission gear 181, based on the midpoint line between the first gear portion 163c and the second gear portion 163d of the drive-side flange 163. That is, in the state of Figure 25(c), there is a deviation LD in the J direction, and in the state of Figure 25(d), there is a deviation LE in the H direction, so the sum of deviation LD and deviation LE (LD + LE) is the amount of change in the balancing position in this modified example.

[0130] If the first gear portion 181c comes into contact with the second gear portion 163d or the second gear portion 181d comes into contact with the main body frame 184, or if the second gear portion 181d comes into contact with the first gear portion 163c, before the drive transmission gear 181 reaches the balancing position, a backlash-less state cannot be achieved even when driven. Therefore, in this modified example, the distance LF (the width of the cylindrical portion 163e) between the first gear portion 163c and the second gear portion 163d of the drive-side flange 163 and the gap LG between the drive transmission gear 181 and the main body frame 184 are set in consideration of the amount of change in the balancing position (LD+LE).

[0131] On the other hand, in the configuration of the present embodiment shown in FIG. 25(a), the first main body gear portion 81c and the second main body gear portion 81d have the same number of teeth, and the positional relationship between the crests 81cs and 81ds of the first main body gear portion 81c and the second main body gear portion 81d does not change with respect to the rotational phase. Therefore, the balance position at which the drive transmission gear 81 is axially positioned relative to the drive-side flange 63 does not change. In other words, the amount of change in the balance position (LD+LE), which was necessary in the modified example, does not need to be considered. Therefore, in this embodiment, the gap between the first gear portion 63c and the second gear portion 63d of the drive-side flange 63 (the width of the cylindrical portion 63e) can be designed smaller than in the modified example, allowing for a more compact cartridge B. Furthermore, the apparatus main assembly A of this embodiment can be designed to have a smaller gap between the drive transmission gear 81 and the main body frame 84 than in the modified example. As a result, the cartridge B and / or the apparatus main assembly A can be made more compact.

[0132] <Other variations> Next, a modified example in which the main changes are in parts other than the drive transmission structure between the drive side flange 63 and the drive transmission gear 81 will be described.

[0133] <Application to cleanerless configuration> In the above-described embodiment, the cartridge B is described as a cartridge B in which the toner remaining on the drum 62 without being transferred is scraped off by the rubber blade 77a abutting against the drum 62 and collected in the waste toner chamber 71b (see FIG. 3). However, the cartridge B may have a cleanerless configuration. In other words, the drive transmission configuration of the drive-side flange 63 and the drive transmission gear 81 of the above-described embodiment may be applied to a cartridge having a cleanerless configuration.

[0134] FIG. 23 is a cross-sectional view of cartridge B with a cleanerless configuration. Cartridge B with a cleanerless configuration is configured and controlled so that residual toner on the drum 62 can be collected by the developing roller 32. Therefore, cartridge B does not have a rubber blade in contact with the drum 62. Therefore, compared to a configuration in which rubber blade 77a abuts against the drum 62, cartridge B with a cleanerless configuration requires less torque to drive the drum 62 due to the absence of rubber blade 77a, which would otherwise provide resistance when rotating the drum 62. As a result, the rotational speed of the drum 62 is more likely to fluctuate due to impacts such as those occurring when the sheet material PA is transported. This means that the rotational accuracy of the drum 62 may be reduced. By applying the drive transmission configuration of the drive-side flange 63 and drive transmission gear 81 of the embodiment described above, the drum 62 can be driven without backlash between the drive-side flange 63 and drive transmission gear 81. Therefore, compared to a configuration in which backlash or play in the rotational direction exists between the drive side flange and the drive member on the main body side that transmits drive to it, it is possible to suppress a decrease in the rotation accuracy of the drum 62 due to the absence of a rubber blade.

[0135] <Application to a configuration without the magnet roller 34> In the above embodiment, the developer carrier is described as having the magnetic roller 34 inside the developing roller 32, but it may be an elastic roller without a magnetic roller inside.

[0136] <Application to a configuration in which the developing roller gear 30 is meshed with the second gear portion 63d> In the above-described embodiment, the developing roller gear 30 is configured to mesh with the first gear portion 63c of the drive-side flange 63. However, the developing roller gear 30 may be configured to mesh with the second gear portion 63d. This configuration will be described with reference to FIG. 29. FIG. 29 is a schematic diagram showing the meshing between the drive-side flange 63 and the developing roller gear 30. The developing roller gear 130 fixed to the end of the developing roller shaft 31 meshes with the second gear portion 63d. Because the second gear portion 63d has a larger torsion angle than the first gear portion 63c, the meshing ratio is correspondingly higher. Therefore, the developing roller gear 130 meshing with the second gear portion 63d can have a smaller tooth width than the developing roller gear 30 meshing with the first gear portion 63d.

[0137] <Application to the drive transmission configuration from the drive side flange to the developing roller gear> Furthermore, a configuration similar to the drive force transmission configuration from the drive transmission gear 81 to the drive-side flange 63 may also be applied to the drive force transmission configuration from the drive-side flange 63 to the developing roller gear 230. This configuration will be described below with reference to Figure 30. Figure 30 is a perspective view of cartridge B. The developing roller gear 230 has a first developing gear portion 230c and a second developing gear portion 230d that mesh with the first gear portion 63c and the second gear portion 63d of the drive-side flange 63, respectively. When the drive-side flange 63 is driven, the developing roller gear 230 moves in the direction of the rotation axis L1 and reaches the balanced position, based on the same principle as in the previously described embodiment, where the drive transmission gear 81 moves in the direction of the rotation axis L1 and reaches the balanced position. When the developing roller gear 230 is in the balanced position, the developing roller gear 230 is driven in a backlash-free state relative to the drive-side flange 63, thereby preventing deterioration in the rotation accuracy of the developing roller 32 due to misalignment or load fluctuations.

[0138] <Application to a configuration in which the developing roller gear is driven without using the drive-side flange> Also, the driving force may be transmitted to the developing roller 532 without passing through the driving-side flange 63. Figure 44 is a partial perspective view of the cartridge B, showing the drive train to the developing roller 532. For the sake of explanation, part of the frame of the cartridge B is not shown.

[0139] As shown in FIG. 44, the developing roller 532 is configured to receive driving force not from the drive-side flange 63 but via another path. Specifically, the cartridge B has a developing coupling member 89 that can engage with a coupling member (not shown) for driving the developing roller of the apparatus main assembly A. Furthermore, the cartridge B is provided with idler gears 90 and 91 that mesh with a gear portion 89a of the developing coupling member 89, and a developing roller gear 530 that meshes with the idler gear 91 at one end of the shaft of the developing roller 532. In this configuration, the developing roller 530 is driven by the driving force received by the developing coupling member 89 transmitted via the idler gears 90 and 91 and the developing roller gear 530. Therefore, it is possible to control the driving of the developing coupling member 89 separately from the driving of the drive-side flange 63, for example, by driving the developing coupling member 89 while the driving of the drive-side flange 63 is stopped.

[0140] <Application to drive transmission configurations for rotating bodies other than drums> Although the drive-side flange 63 is attached to the end of the drum 62, it is also possible to provide the first gear portion 63c, the second gear portion 63d, and the cylindrical portion 63e on the developing roller gear 30, and to apply a configuration in which the drive transmission gear 81 drives the developing roller 30. Furthermore, the object driven by the drive transmission gear 81 is not limited to a developer carrier that carries toner (developer), such as the drum 62 or the developing roller 30. The object driven by the drive transmission gear 81 may be, for example, a conveying member (or agitating member) 43 that conveys (or agitates) toner, the charging roller 66, or a supplying member that supplies toner to the developing roller 30. Furthermore, when the object driven by the drive transmission gear 81 is a member other than the drum 62 included in the cartridge B, the cartridge B may be a cartridge that does not have a photosensitive member, such as the drum 62.

[0141] [Example 2] Next, a second embodiment will be described below with reference to Figure 31. This embodiment differs from the first embodiment in the configuration of the first gear portion and the second gear portion provided on the drive side flange. Other points are the same as those of the first embodiment, so a description thereof will be omitted.

[0142] FIG. 31 is a cross-sectional view of the meshing portion between the drive transmission gear 81 and the drive-side flange 263, and the cross-section is a plane tangent to the meshing pitch circle. The drive-side flange 263 has a first gear portion (first unit side gear portion) 263c and a second gear portion (second unit side gear portion) 263d. The first gear portion 263c includes a plurality of first spur teeth (first protrusions) 263ct with a tooth width that can fit between the teeth of the first main body gear portion 81c. The second gear portion 263d includes a plurality of second spur teeth (second protrusions) 263dt with a tooth width that can fit between the teeth of the second main body gear portion 81d. The width (tooth width) of the first spur teeth 263ct in the direction of the rotation axis L1 is greater than the width (tooth width) of the second spur teeth 263dt in the direction of the rotation axis L1. The first and second spur teeth are projections that protrude in the radial direction around the rotation axis L1, and are arranged at positions offset in the circumferential direction around the rotation axis L1.

[0143] Even when such a drive-side flange 263 is used, rotation of the drive transmission gear 81 in the I direction causes the drive transmission gear 81 to move to a balanced position, resulting in a backlash-less state similar to that of the first embodiment. That is, the first main body gear portion 81c meshes with the first gear portion 263c and receives a reaction force of the drive force FD and a thrust force F209 in the J direction from a contact point (contact portion) CP1 of the first gear portion 263c. The second main body gear portion 81d meshes with the second gear portion 263d and receives a reaction force of the restricting force FB and a thrust force F210 in the H direction from a contact point (contact portion) CP2 of the second gear portion 263d. As a result, the drive transmission gear 81 is sandwiched between the first gear portion 263c and the second gear portion 263d of the drive-side flange 263 in the axial rotation direction, resulting in a backlash-less state similar to that of the first embodiment.

[0144] [Example 3] Next, a third embodiment will be described below with reference to Figure 32. This embodiment differs from the first embodiment in the configuration of the first gear portion and the second gear portion provided on the drive side flange. Other points are the same as those of the first embodiment, so a description thereof will be omitted.

[0145] FIG. 32 is a diagram showing the drive-side flange 363. The drive-side flange 363 has a first gear portion 363c and a second gear 363d1. The first gear portion (first unit side gear portion) 363c includes a plurality of first helical gears (first protrusions) 363ct that are divided into multiple parts in the direction of the rotation axis L1. Although the multiple first helical gears (protrusions) 363ct are divided in the direction of the rotation axis L1, they function as a single helical gear extending substantially in the direction of the rotation axis L1 with respect to the first main body gear portion 81c. Furthermore, the tooth surfaces of the multiple first helical gears (protrusions) 363ct are multiple force receiving portions that receive force from the first main body gear portion 81c. Therefore, it can be said that the multiple force receiving portions that receive force from the first main body gear portion 81c are provided across the multiple first helical gears (first protrusions) 363ct. The tooth surfaces of the multiple first helical gears (protrusions) 363ct can be said to form multiple divided helical surfaces in the direction of the rotation axis L1, or to form multiple divided helical surfaces in the circumferential direction centered on the rotation axis L1 of the drive-side flange 363. In this way, the multiple helical protrusions 363ct form one tooth of the helical gear corresponding to one tooth of the first main body gear portion 81c.

[0146] The tooth surfaces of the multiple second helical gears (protrusions) 363dt are multiple force receiving portions that receive force from the second main body gear portion 81d. Therefore, it can be said that the multiple force receiving portions that receive force from the second main body gear portion 81d are provided across the multiple second helical gears (second protrusions) 363dt. The second gear portion (second unit side gear portion) 363d includes multiple second helical gears (protrusions) 363dt that are divided into multiple parts in the direction of the rotation axis L1. Although the multiple second helical gears (second protrusions) 363dt are divided in the direction of the rotation axis L1, they function substantially as a single helical tooth extending in the direction of the rotation axis L1 with respect to the second main body gear portion 81d. Moreover, it can be said that the tooth surfaces of the plurality of second helical gears (protrusions) 363dt form a plurality of divided helical surfaces in the direction of the rotation axis L1, or form a plurality of divided helical surfaces in the circumferential direction centered on the rotation axis L1 of the drive-side flange 363. In this way, the plurality of helical protrusions 363dt form one tooth of the helical gear corresponding to one tooth of the second main body gear portion 81d.

[0147] Therefore, even when such a driving side flange 363 is used, when the drive transmission gear 81 rotates in the I direction, the drive transmission gear 81 moves to the balanced position, and a backlash-less state is achieved as in the first embodiment.

[0148] [Example 4] Next, a fourth embodiment will be described below with reference to Figure 33. This embodiment differs from the first embodiment in the configuration of the first gear portion and the second gear portion provided on the drive side flange. Other points are the same as those of the first embodiment, so a description thereof will be omitted.

[0149] The drive-side flange 463 has two gear portions (a first unit-side gear portion and a second unit-side gear portion) similar to the first gear portion 63c and the second gear portion 63d of the drive-side flange 63 of the first embodiment. At least one of the two gear portions has a missing tooth portion 463L (a portion where the gear teeth are apparently thinned out). Figure 33(a) is a cross-sectional view of the drive-side flange 463 and the drive transmission gear 81 meshed with each other, taken perpendicular to the rotation axis L1. Figure 33(b) is a graph showing the transition in the number of teeth of the meshing gears. If the meshing ratio between each gear portion of the drive-side flange 463 and each gear portion of the drive transmission gear 81 is N teeth, rounded down to the nearest whole number, each gear portion of the drive-side flange 463 may have a missing tooth portion 463L at a maximum of every N-1 teeth. By satisfying this condition, even if there is a toothless portion 463L, there will be at least one tooth that meshes with the drive transmission gear 81 (the meshing ratio will be 1 or more). With this configuration, when the drive transmission gear 81 rotates in the I direction, the drive transmission gear 81 moves to a balanced position and enters a backlash-less state as in Example 1. Note that, as shown in Figure 33(b), the number of gear teeth of the drive-side flange 463 that mesh with each gear portion of the drive transmission gear 81 changes during driving.

[0150] [Example 5] Next, a fifth embodiment will be described below with reference to Figure 34. This embodiment differs from the first embodiment in the configuration of the first gear portion and the second gear portion provided on the drive side flange. Other points are the same as those of the first embodiment, so a description thereof will be omitted.

[0151] The drive-side flange 563 has two gear portions (a first unit-side gear portion and a second unit-side gear portion) similar to the first gear portion 63c and the second gear portion 63d of the drive-side flange 63 of the first embodiment. At least one of the two gear portions has a tooth-missing portion 563L. FIG. 34(a) is a cross-sectional view of the drive-side flange 563 and the drive transmission gear 81 meshed with each other, taken perpendicular to the rotation axis L1. FIG. 34(b) is a diagram showing the transition of the number of teeth of the meshed gears. As shown in FIG. 34(a), unlike the drive-side flange 463 of the fourth embodiment, the teeth of the drive-side flange 563 are not arranged at equal intervals in the circumferential direction. In other words, the tooth-missing portions 563 do not have a uniform size in the circumferential direction, or the apparent amount of tooth-missing is not the same for all of the tooth-missing portions 563. In other words, the tooth-missing portions 563 may be arranged in the rotational direction at intervals LI and LJ that are a natural number (1, 2, . . . ) times the minimum pitch LH between adjacent teeth. Even if such a toothless portion 563 is provided, it is sufficient that there is at least one meshing tooth (the meshing ratio is 1 or more). With this configuration, when the drive transmission gear 81 rotates in the I direction, the drive transmission gear 81 moves to the balanced position and enters a backlash-less state as in Example 1. Note that, as shown in Figure 34(b), the number of gear teeth of the drive-side flange 463 that mesh with each gear portion of the drive transmission gear 81 changes.

[0152] [Example 6] Next, a sixth embodiment will be described below with reference to Figure 35. This embodiment differs from the first embodiment in the configuration of the first gear portion and the second gear portion provided on the drive-side flange. Specifically, while the first gear portion 63c and the second gear portion 63d in the first embodiment each have helical teeth with an involute tooth profile, this embodiment differs in that they have helical teeth that are not involute teeth. Other points are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0153] FIG. 35 is a perspective view of the drive-side flange 763. The drive-side flange 763 has a first gear portion (first unit side gear portion) 763c and a second gear portion (second unit side gear portion) 763d. The first gear portion 763c includes a plurality of first protrusions 763ct, and the second gear portion 763d includes a plurality of second protrusions 763dt. The first protrusions 763ct and the second protrusions 763dt are protrusions that protrude in the radial direction centered on the rotation axis L1, and their cross-sectional shapes in a cross section perpendicular to the rotation axis L1 are trapezoids that narrow toward the tips. In addition, the first protrusions 763ct and the second protrusions 763dt have helical teeth that are arranged twisted with respect to the rotation axis L1. Even with this configuration, the first gear portion 763c and the second gear portion 763d function as helical gears when meshing with the drive transmission gear 81. Therefore, when the drive transmission gear 81 rotates in the I direction, the drive transmission gear 81 moves to the balanced position, and a backlash-free state is achieved, similar to the first embodiment.

[0154] The cross-sectional shape of the first protrusion 763ct and the second protrusion 763dt is not limited to a trapezoid, but may be a rectangle, a triangle, a mountain shape formed by curves, or a shape with chamfered corners.

[0155] [Example 7] Next, Example 7 will be described below with reference to Figure 36. This example differs from Example 1 in the configuration of the first gear portion and second gear portion provided on the drive side flange. Specifically, the twist direction is reversed compared to the first gear portion 63c and second gear portion 63d of Example 1. Accordingly, the twist direction of the first main body gear portion and second main body gear portion of the drive transmission gear is also reversed compared to Example 1. Other points are the same as Example 1, so description will be omitted.

[0156] Figure 36 is a schematic diagram showing the meshing between the drive transmission gear 881 and the drive-side flange 863. As shown in Figure 36, the twist directions of the first gear portion (first unit side gear portion) 863c and the second gear portion (second unit side gear portion) 863d of the drive-side flange 863 are such that the tooth surfaces are displaced in the I direction as they move in the J direction. The twist directions of the first gear portion 881c and the second gear portion 881d of the drive transmission gear 881 are such that the tooth surfaces are displaced in the K direction as they move in the J direction.

[0157] Since the twist direction is opposite to that of Example 1, the direction of the thrust force F21 acting on the drive transmission gear 881 due to meshing while the drive transmission gear 881 is being driven is also opposite to that of Example 1. Therefore, when moving to a balanced position in the axial direction, a space with a width LK is required for the drive transmission gear 881 to move in the H direction. For this reason, a compression spring 185 is provided that biases the drive transmission gear 881 in the J direction, and the drive transmission gear 881 is positioned so that it abuts against the positioning portion 83b of the second drive-side side plate 83 before the cartridge B is attached.

[0158] Even with this configuration, when the drive transmission gear 881 rotates in the I direction, the drive transmission gear 881 moves to the balanced position, and a backlash-free state is achieved as in the first embodiment.

[0159] [Example 8] Next, an eighth embodiment will be described with reference to Figure 37. This embodiment differs from the first embodiment in the configuration for mounting the cartridge B to the main assembly of the apparatus. Other points are the same as those of the first embodiment, so a description thereof will be omitted.

[0160] 37 is a perspective view of an image forming apparatus 800. In this image forming apparatus 800, the insertion direction of cartridge B into the apparatus main assembly A is parallel or approximately parallel to the rotation axis L1 of the drum 62. Even if cartridge B is completely inserted in the direction parallel to the rotation axis L1, the drive-side flange 63 and a drive transmission gear (not shown) of the apparatus main assembly A cannot mesh with each other because there is a distance between them in a direction perpendicular to the rotation axis L1. Thereafter, by closing the door 211, a lift-up mechanism (not shown) provided in the apparatus main assembly A connected to the door 211 displaces cartridge B at least in the direction VD perpendicular to the rotation axis L1, thereby causing the drive-side flange 63 to mesh with the drive transmission gear (not shown) of the apparatus main assembly A.

[0161] The driving operation after the drive side flange 63 and the drive transmission gear (not shown) mesh together is the same as in the first embodiment, and the drive transmission gear moves to the balanced position, resulting in a backlash-free state as in the first embodiment.

[0162] When the lift-up mechanism displaces the cartridge B at least in the direction VD perpendicular to the rotational axis L1, the cartridge B may be displaced not only in the direction perpendicular to the rotational axis L1 but also along the direction of the rotational axis L1. Alternatively, the lift-up mechanism may rotate the cartridge B about an axis perpendicular to the rotational axis L1, thereby displacing the driving-side flange 63 in the direction VD perpendicular to the rotational axis L1.

[0163] Furthermore, instead of a configuration in which the door 211 is closed and the lift-up mechanism is operated after cartridge B has been completely inserted into the apparatus main body A, cartridge B may be displaced at least in the direction VD perpendicular to the rotation axis L1 during the process of inserting cartridge B into the apparatus main body A. Specifically, in the initial stage of the process of inserting cartridge B into the apparatus main body A, cartridge B is guided by a guide (not shown) so as to move cartridge B in a direction parallel to the rotation axis L1. Then, in the final stage of the insertion process, cartridge B is guided by a guide (not shown) so as to displace cartridge B at least in the direction VD perpendicular to the rotation axis L1. In this way, a configuration in which the moving direction (mounting direction) of cartridge B changes during the insertion process may be adopted.

[0164] [Example 9] Next, Example 9 will be described below with reference to Figure 38. This example differs from Example 1 in the configuration of the first gear portion and second gear portion provided on the drive-side flange. Specifically, in this example, the arrangement of the first gear portion 963c and the second gear portion 963d in relation to the direction of the rotation axis L1 is reversed from the first gear portion 63c and the second gear portion 63d in Example 1. Accordingly, the positions of the first main body gear portion and the second main body gear portion of the drive transmission gear in relation to the direction of the rotation axis L1 are also reversed compared to Example 1. Other points are the same as Example 1, so description thereof will be omitted.

[0165] FIG. 38 is a schematic diagram showing the meshing between the drive transmission gear 981 and the drive-side flange 963. The drive-side flange 963 has a first gear portion (first unit side gear portion) 963c and a second gear portion (second unit side gear portion) 963d. The torsion angle of the second gear portion 963d is larger than the torsion angle of the first gear portion 963c. The first gear portion 963c is located downstream (on the drive side) in the J direction from the second gear portion 963d. In other words, with respect to the direction of the rotation axis L1, the second gear portion 963d is located between the first gear portion 963c and the drum 62. The drive transmission gear 981 similarly has a first gear portion 981c that meshes with the first gear portion 963c and a second gear portion 981d that meshes with the second gear portion 963d. Again, the positions of these with respect to the direction of the rotation axis L1 are opposite to those in the first embodiment.

[0166] Even with this configuration, when the drive transmission gear 981 is driven, the drive transmission gear 981 moves to a balanced position. During subsequent driving, the first gear portion 963c receives the driving force FD (see FIG. 17(d)), and the second gear portion 963d receives the restricting force FB (see FIG. 17(d)), similar to the first embodiment, resulting in a backlash-less state.

[0167] Here, the drive-side end (downstream side in the J direction) of the drum unit 969, in which the drive-side flange 963 and the drum 62 are integrated, is rotatably supported by the shaft member 86 (see also FIG. 4). The first gear portion 963c is located closer to the base of the shaft member 86 than the second gear portion 963d. Furthermore, the first gear portion 963c, which receives the drive force FD, exerts a greater force on the tooth surface of the drive-side flange 963 than the second gear portion 963d, which receives the restraining force FB. Therefore, the drive force FD may act to tilt the rotation axis L1 of the drum unit 969, causing the drum 62 to tilt relative to the ideal rotation axis L1. However, in this embodiment, by locating the first gear portion 963c, which receives the drive force FD, closer to the base of the shaft member 86 than the second gear portion 963d, it is possible to suppress the tilt of the rotation axis L1 of the drum unit 969 caused by the drive force FD.

[0168] [Example 10] Next, Example 10 will be described below with reference to Figure 39. This example differs from Example 1 in the configuration of the first gear portion and the second gear portion provided on the drive-side flange. Specifically, while the positions and widths of the teeth of the first gear portion 63c and the second gear portion 63d in Example 1 were the same in the direction of the rotation axis L1, this example differs in that the positions and widths of the teeth in the direction of the rotation axis L1 are not the same. Other points are the same as in Example 1, so description thereof will be omitted.

[0169] 39 is a cross-sectional view of the meshing portion between the drive transmission gear 81 and the drive-side flange 1063, and the cross section is a plane tangent to the meshing pitch circle. The drive-side flange 1063 is provided with a first gear portion (first unit side gear portion) 1063c and a second gear portion (second unit side gear portion) 1063d. The first gear portion 1063c includes a plurality of first helical teeth (first protrusions) 1063ct that vary in width and position relative to the direction of the rotation axis L1. The second gear portion 1063d includes a plurality of second helical teeth (second protrusions) 1063dt that vary in width and position relative to the direction of the rotation axis L1.

[0170] In this configuration, although the meshing ratio is different from when the drive-side flange 63 of Example 1 is used, the first gear portion 1063c and the second gear portion 1063d function as helical gears similar to the first gear portion 63c and the second gear portion 63d, respectively. Therefore, when the drive transmission gear 81 rotates in the I direction, the drive transmission gear 81 moves to the balanced position, and a backlash-less state is achieved similar to Example 1.

[0171] [Example 11] Next, an eleventh embodiment will be described below with reference to Figure 40. This embodiment differs from the first embodiment in the configuration of the second gear portion provided on the drive-side flange. Specifically, the second gear portion 63d in the first embodiment is a helical gear, whereas in this embodiment it is a spur gear. Other points are the same as in the first embodiment, and therefore description thereof will be omitted.

[0172] FIG. 40 is a cross-sectional view of the meshing portion between the drive transmission gear 81 and the drive-side flange 1163, and the cross section is a plane tangent to the meshing pitch circle. The drive-side flange 1163 is provided with a first gear portion (first unit side gear portion) 1163c and a second gear portion (second unit side gear portion) 1163d. The first gear portion 1163c is the same as the first gear portion 63c of the first embodiment. The second gear portion 1163d includes a plurality of second spur teeth (teeth, second protrusions) 1163dt. The plurality of second spur teeth 1163dt are spur teeth with a tooth width and tooth thickness large enough to be inserted between the teeth (valley portions) of the second main body gear portion 81d of the drive transmission gear 81. Therefore, the width (tooth width) of the second spur teeth (second protrusions) 1163dt in the direction of the rotation axis L1 is smaller than the width (tooth width) of the first gear portion 1163c in the direction of the rotation axis L1. In other words, the second gear portion 1163d has second spur teeth (second projections) 1163dt that are narrower than the first helical teeth of the first gear portion 1163c that have the widest width (tooth width) in the direction of the rotation axis L1.

[0173] Furthermore, the width (length) of the second protrusion 1163dt in the rotational direction (I direction) or circumferential direction is smaller than the width (length) of one tooth of the first gear portion 1163c in the rotational direction (I direction). In other words, the second gear portion 1163d has the second protrusion 1163dt that is narrower in the rotational direction (I direction) or circumferential direction than the first helical tooth of the first gear portion 1163c that has the widest width (length) in the rotational direction (I direction) or circumferential direction.

[0174] The second protrusion 1163dt also has a contact portion CP2 that comes into contact with the second main body gear portion 81d. As shown in FIG. 40, the contact portion CP2 is provided at a corner of the second protrusion 1163dt. The corner (contact point CP2) is provided so that the corner (contact point CP2) comes into contact with one tooth of the second main body gear portion 81d at only one point in the direction of the rotation axis L1. The radius of curvature of this corner can be set to a desired value. A smaller radius of curvature may result in a sharper corner, or a larger radius of curvature may result in a gentler corner, as in the second protrusion 1363dt shown in Example 13 described below.

[0175] When the drive transmission gear 81 is driven, it receives a thrust force F1109 in the J direction and moves in the J direction, similar to the first embodiment. Then, the surface 81d2 on the upstream side in the I direction of the second main body gear portion 81d comes into contact with the contact portion CP2 of the second spur tooth 1163dt of the second gear 1163d and receives a thrust force F1110 in the H direction. Therefore, using the same principle as the first embodiment, the drive transmission gear 81 is positioned at the balanced position and enters a backlash-free state. Furthermore, in the backlash-free state, with respect to drive in the rotational direction, the first gear portion 1163c receives a driving force FD, and the second gear portion 1163d receives a restricting force FB at the contact portion CP2 of the second spur tooth 1163dt.

[0176] [Example 12] Next, Example 12 will be described below with reference to Figure 41. This example differs from Example 1 in the configuration of the second gear portion provided on the drive-side flange. Specifically, while the twist angle of the second gear portion 63d in Example 1 was larger than the twist angle of the first gear portion 63c, the twist angle of the second gear portion 1263d in this example is not larger. Other points are the same as in Example 1, so description thereof will be omitted.

[0177] FIG. 41 is a cross-sectional view of the meshing portion between the drive transmission gear 81 and the drive-side flange 1263, and the cross-section is a plane tangent to the meshing pitch circle. The drive-side flange 1263 is provided with a first gear portion (first unit side gear portion) 1263c and a second gear portion (second unit side gear portion) 1263d. The first gear portion 1263c is the same as the first gear portion 63c of the first embodiment. The second gear portion 1263d includes a plurality of second helical teeth (teeth, second protrusions) 1263dt. The helix angle of the plurality of second helical teeth 1263dt is the same as the helix angle of the helical teeth of the first gear portion 1263c. Similar to the plurality of second helical teeth 1163dt of the eleventh embodiment, the plurality of second helical teeth 1263dt are helical teeth with a tooth width and thickness large enough to be inserted between the teeth (valley portions) of the second main body gear portion 81d of the drive transmission gear 81. For this reason, the width (tooth width) of the second helical teeth (second protrusions) 1263dt in the direction of the rotation axis L1 is smaller than the width (tooth width) of the first gear portion 1263c in the direction of the rotation axis L1. In other words, the second gear portion 1263d has second helical teeth (second protrusions) 1263dt that are narrower than the first helical teeth of the first gear portion 1263c, which have the widest width (tooth width) in the direction of the rotation axis L1.

[0178] Furthermore, the width (length) of the second protrusion 1263dt in the rotational direction (I direction) or circumferential direction is smaller than the width (length) of one tooth of the first gear portion 1263c in the rotational direction (I direction). In other words, the second gear portion 1263d has the second protrusion 1263dt that is narrower in the rotational direction (I direction) or circumferential direction than the first helical tooth of the first gear portion 1263c that has the widest width (length) in the rotational direction (I direction) or circumferential direction.

[0179] The second protrusion 1263dt also has a contact portion CP2 that comes into contact with the second main body gear portion 81d. As shown in FIG. 40, the contact portion CP2 is provided at a corner of the second protrusion 1263dt. The corner (contact point CP2) is provided so that the corner (contact point CP2) comes into contact with one tooth of the second main body gear portion 81d at only one point in the direction of the rotation axis L1. The radius of curvature of this corner can be set to a desired value; a sharper corner may be obtained by reducing the radius of curvature, or a gentler corner may be obtained by increasing the radius of curvature, as in the second protrusion 1363dt shown in Example 13 described below.

[0180] When the drive transmission gear 81 is driven, it receives a thrust force F1209 in the J direction and moves in the J direction, as in the first embodiment. Then, the surface 81d2 on the upstream side in the I direction of the second main gear portion 81d comes into contact with the contact portion CP2 of the second helical teeth 1163dt of the second gear portion 1263d and receives a thrust force F1210 in the H direction. Therefore, based on the same principle as in the first embodiment, the drive transmission gear 81 is positioned at the balanced position and enters a backlash-free state. Furthermore, in the backlash-free state, with respect to drive in the rotational direction, the first gear portion 1263c receives a driving force FD, and the second gear portion 1263d receives a restricting force FB at the contact portion CP2 of the second helical teeth 1263dt.

[0181] [Example 13] Next, a thirteenth embodiment will be described below with reference to Figure 42. This embodiment differs from the first embodiment in the configuration of the portion corresponding to the second gear portion provided on the drive-side flange. Specifically, the second gear portion 63d in the first embodiment was a helical gear, but in this embodiment it is a plurality of cylindrical protrusions. Other points are the same as in the first embodiment, so a description thereof will be omitted.

[0182] Figure 42(a) is a perspective view of the drive side flange 1363. Figure 42(b) is a cross-sectional view of the meshing portion between the drive transmission gear 81 and the drive side flange 1363, and the cross section is a plane tangent to the meshing pitch circle thereof.

[0183] A first gear portion (first unit side gear portion) 1363c and a second gear portion (second unit side gear portion) 1363d are provided on the driving side flange 1363. The first gear portion 1363c is the same as the first gear portion 63c of the first embodiment.

[0184] The second gear portion 1363d includes a tooth root cylindrical portion (base cylindrical portion) 1363Bd extending along the rotation axis L1 and a plurality of cylindrical second protrusions (teeth) 1363dt protruding in the radial direction centered on the rotation axis L1. The second gear portion 1363d is a rotating portion that rotates integrally with the first gear portion 1363c. The plurality of second protrusions 1363dt are arranged at the same position in the direction of the rotation axis L1 (on the same plane perpendicular to the rotation axis L1).

[0185] Furthermore, when viewed along the rotation axis L1, the tips S of the multiple second protrusions 1363dt are arranged on a predetermined circumference centered on the rotation axis L1 and are arranged at equal intervals in the circumferential direction. The tip circle of the second gear portion 1363d is a circle drawn as a rotation locus by the tip S of the multiple second protrusions 1363dt that is farthest from the rotation axis (rotation axis L1) of the second gear portion 1363d when the drive-side flange 1363 rotates. In this embodiment, all of the second protrusions 1363dt have the same shape, and therefore the distances from the rotation axis L1 of the tips S of all of the second protrusions 1363dt to the tip S are the same, and therefore all of the tips S draw the same rotation locus. The diameter / radius of the circle of this rotation locus is defined as the tip circle diameter / tip circle radius of the second gear portion 1363d.

[0186] The multiple second protrusions 1363dt have a width in the direction of the rotation axis L1 and in the rotation direction (direction I) large enough to be inserted between teeth (valley portions) of the second main gear portion 81d of the drive transmission gear 81. Therefore, the width of the second protrusions 1363dt in the direction of the rotation axis L1 is smaller than the width (tooth width) of the first gear portion 1363c in the direction of the rotation axis L1. In other words, the second gear portion 1363d has second protrusions 1363dt that are narrower in the direction of the rotation axis L1 than the first helical tooth of the first gear portion 1363c, which has the widest width (tooth width) in the direction of the rotation axis L1. Furthermore, the width (length) of the second protrusions 1363dt in the rotation direction (direction I) or circumferential direction is smaller than the width (length) of one tooth of the first gear portion 1363c in the rotation direction (direction I) or circumferential direction. In other words, the second gear portion 1363d has a second protrusion 1363dt that is narrower in the rotational direction (I direction) or circumferential direction than the first helical tooth of the first gear portion 1363c, which has the widest width (length) in the rotational direction (I direction) or circumferential direction.

[0187] The second protrusion 1363dt also has a contact portion CP2 that comes into contact with the second main body gear portion 81d. As shown in FIG. 42(b), the contact portion CP2 is provided on a curved portion of the surface of the second protrusion 1363dt. This curved portion of the surface of the second protrusion 1363dt can be considered a corner. The corner (contact point CP2) is provided so that the corner (contact point CP2) comes into contact with one tooth of the second main body gear portion 81d at only one point in the direction of the rotation axis L1. The curvature radius of this corner can be set to a desired value; a smaller curvature radius can result in a sharper corner, or a larger curvature radius can result in a gentler corner.

[0188] When the drive transmission gear 81 is driven, the drive transmission gear 81 receives a thrust force in the J direction and moves in the J direction, as in the first embodiment. Then, the surface 81d2 on the upstream side in the I direction of the second main body gear portion 81d comes into contact with the contact portion CP2 of the second protrusion 1363dt of the second gear portion 1163d and receives a thrust force F1310 in the H direction. Therefore, using the same principle as in the first embodiment, the drive transmission gear 81 is positioned at a balanced position and enters a backlash-free state. Furthermore, in the backlash-free state, with respect to drive in the rotational direction, the first gear portion 1363c receives a driving force FD, and the second gear portion 1363d receives a restricting force FB at the contact portion CP2 of the second protrusion 1363dt.

[0189] In addition, the second gear portion 1363d can use multiple second protrusions 1363dt to mesh with other gears such as the second main body gear portion 81d and receive rotational driving force and / or thrust force, and in this respect can be considered a type of gear.

[0190] Furthermore, the multiple second protrusions 1363dt are not limited to being cylindrical, and may have any shape that protrudes at least in the radial direction centered on the rotation axis L1, such as a polygonal column shape. Furthermore, all of the multiple second protrusions 1363dt do not have to have the same shape.

[0191] [Example 14] Next, Example 14 will be described below with reference to Figure 43. This example differs from Example 1 in the configuration of the portion corresponding to the second gear portion provided on the drive-side flange. Specifically, the second gear portion 63d in Example 1 was a helical gear, but in this example it is a plurality of cylindrical protrusions. Since all other points are the same as Example 1, a description thereof will be omitted. Furthermore, when comparing this example with Example 13, only the arrangement of the plurality of cylindrical protrusions is different.

[0192] Figure 43(a) is a cross-sectional view of the teeth and protrusions of the drive-side flange 1463, and the cross-section is a plane tangent to a circle centered on the rotation axis L1. Figure 43(b) is a cross-sectional view of the meshing portion between the drive transmission gear 81 and the drive-side flange 1463, and the cross-section is a plane tangent to the meshing pitch circle.

[0193] A first gear portion (first unit side gear portion) 1463c and a second gear portion (second unit side gear portion) 1463d are provided on the driving side flange 1463. The first gear 1463c is the same as the first gear portion 63c of the first embodiment.

[0194] The second gear 1463d includes a plurality of cylindrical second protrusions 1463dt that protrude in the radial direction around the rotation axis L1. The second gear portion 1463d is a rotating portion that rotates integrally with the first gear portion 1463c. The multiple second protrusions 1463dt are arranged at offset positions with respect to the direction of the rotation axis L1.

[0195] Furthermore, when viewed along the rotation axis L1, the tips S of the multiple second protrusions 1463dt (see FIG. 42(a)) are arranged on a predetermined circumference centered on the rotation axis L1. The multiple second protrusions 1463dt are protrusions with a width in the direction of the rotation axis L1 and the rotation direction (direction I) that is large enough to be inserted between the teeth (valley portions) of the second main gear portion 81d of the drive transmission gear 81. The multiple second protrusions 1463dt are arranged at positions that allow them to be inserted between the teeth (valley portions) of the second main gear portion 81d of the drive transmission gear 81 and receive the restraining force FB from the second main gear portion 81d in a backlash-free state. Specifically, as shown in FIG. 43(a), multiple imaginary twist lines (spiral lines) L9 twisted at the same angle as the twist angle α2 of the second main gear portion 81d are drawn at a predetermined pitch P9 on a cylindrical surface centered on the rotation axis L1. This pitch P9 is the same as the pitch in a direction perpendicular to the tooth surfaces of the multiple second helical teeth 81dt of the second main gear portion 81d of the drive transmission gear 81. The multiple second protrusions 1463dt are arranged so as to satisfy the following condition in relation to the multiple torsion lines L9: some of the multiple torsion lines L9 must be in contact with some of the multiple second protrusions 1463dt, and none of the multiple torsion lines L9 must pass through the cross section of the multiple second protrusions 1463dt. By arranging the multiple second protrusions 1463dt to satisfy this condition, the multiple second protrusions 1463dt can perform the same function as the multiple second protrusions 1363dt of Example 13, that is, receive the restraining force FB from the second main gear portion 81d in a backlash-free state. Also, similar to Example 13, the corner portion (contact point CP2) of the second protrusion 1463dt is positioned so that the corner portion (contact point CP2) contacts one tooth of the second main body gear portion 81d at only one point in the direction of the rotation axis L1.

[0196] When the drive transmission gear 81 is driven, as shown in FIG. 43(b), the drive transmission gear 81 receives a thrust force F1409 and moves in the J direction, similar to the first embodiment. Then, the surface 81d2 upstream of the second main body gear portion 81d in the I direction comes into contact with the contact portion CP of the second protrusion 1463dt of the second gear portion 1463d and receives a thrust force F1410 in the H direction. Therefore, the drive transmission gear 81 is positioned at a balanced position based on the same principle as the first embodiment, and enters a backlash-free state. Furthermore, in the backlash-free state, with respect to drive in the rotational direction, the first gear portion 1463c receives a driving force FD, and the second gear portion 1463d receives a restricting force FB at the contact portion CP2 of the second protrusion 1463dt.

[0197] In addition, the second gear portion 1463d can use multiple second protrusions 1463dt to mesh with other gears such as the second main body gear portion 81d and receive rotational driving force and / or thrust force, and in this respect can be considered a type of gear.

[0198] Furthermore, the multiple second protrusions 1463dt are not limited to a cylindrical shape, and may have any shape that protrudes at least in the radial direction centered on the rotation axis L1, and all of the multiple second protrusions 1463dt do not have to have the same shape.

[0199] [Example 15] Next, a fifteenth embodiment will be described with reference to Figure 45. The drive transmission configuration inside cartridge B differs from that of embodiment 1. Figure 45(a) is a partial cross-sectional view of the drum 62 of cartridge B, taken along a plane including rotation axis L1. Figure 45(b) is a view of the drum 62 and developing roller 632 of cartridge B, viewed in a direction perpendicular to rotation axis L1.

[0200] The gear that meshes with the drive transmission gear 81 does not need to be fixed integrally to the end of the drum 62. As shown in FIG. 45(a), the driven gear 1563 that meshes with the drive transmission gear 81 is rotatably supported at both ends by a shaft 1578 fixed to one end of the cleaning frame 1571. In other words, the shaft 1578 supports the driven gear 1563 while passing through the driven gear 1563. The driven gear 1563 has a first gear portion (first unit side gear portion) 1563c that is a helical gear with a torsion angle α1 and a second gear portion (second unit side gear portion) 1563d that is a helical gear with a torsion angle α2, similar to the first gear portion 63c and the second gear portion 63d provided on the drive-side flange 63 in the first embodiment. Furthermore, a developing roller gear 630 that meshes with a second gear portion 1563d of a driven gear 1563 is provided integrally with the developing roller 632 at one end thereof, and a drum drive gear 92 is provided integrally with the developing roller 632 at the other end thereof. A drum gear 93 that meshes with the drum drive gear 92 is attached integrally to one end of the drum 62 by caulking or the like, and is rotatably supported by a drum shaft. A drum flange 1564 is attached to the other end of the drum by caulking or the like, and is rotatably supported by a shaft 1578. With this configuration, the driving force received by the driven gear 1563 from the drive transmission gear 81 is transmitted to the drum 62 in the order of the developing roller gear 630, the developing roller 632, the drum drive gear 92, and the drum gear 93.

[0201] [Example 16] Next, Example 15 will be described below with reference to Figure 48. This example differs from Example 1 in the configuration of the portions corresponding to the first gear portion and the second gear portion provided on the drive-side flange. Specifically, while the first gear portion 63c and the second gear portion 63d in Example 1 were helical gears, this example differs in that each gear portion is formed of a plurality of protrusions (each tooth of the gear portion is formed by a plurality of protrusions). Other points are the same as in Example 1, so description thereof will be omitted.

[0202] Figure 48(a) is a cross-sectional view of the teeth and protrusions of the drive-side flange 1663, and the cross-section is a plane tangent to a circle centered on the rotation axis L1. Figure 48(b) is a cross-sectional view of the meshing portion between the drive transmission gear 81 and the drive-side flange 1663, and the cross-section is a plane tangent to the meshing pitch circle.

[0203] The first gear portion (first unit side gear portion, first unit side helical gear portion) 1663c includes a plurality of cylindrical first protrusions 1663ct that protrude in the radial direction centered on the rotation axis L1 from a tooth root cylindrical portion (base cylindrical portion) that extends along the rotation axis L1. The plurality of first protrusions 1663ct are arranged at the same position and at offset positions in the direction of the rotation axis L1.

[0204] Furthermore, when viewed along the rotation axis L1, the tips S of the multiple first protrusions 1663ct (see FIG. 42(a)) are arranged on a predetermined circumference centered on the rotation axis L1. The multiple first protrusions 1663ct are protrusions with a width in the direction of the rotation axis L1 and the rotation direction (direction I) that is large enough to be inserted between the teeth (valley portions) of the first main gear portion 81c of the drive transmission gear 81. The multiple first protrusions 1663dt are arranged in positions that allow them to be inserted between the teeth (valley portions) of the first main gear portion 81c of the drive transmission gear 81 and receive the driving force FD from the first main gear portion 81c in a backlash-free state. Specifically, as shown in FIG. 48(a), multiple imaginary twist lines (spiral lines) L15 twisted at the same angle as the twist angle α1 of the first main gear portion 81c are drawn at a predetermined pitch P11 on a cylindrical surface centered on the rotation axis L1. This pitch P11 is the same as the pitch in a direction perpendicular to the tooth surfaces of the multiple first helical teeth 81ct of the first main gear portion 81c of the drive transmission gear 81. The multiple first protrusions 1663dt are arranged so as to satisfy the following condition in relation to the multiple torsion lines L5: some of the multiple torsion lines L15 must be in contact with some of the multiple first protrusions 1663ct, and the multiple torsion lines L11 must be arranged so that none of the multiple torsion lines L11 passes through the cross section of the multiple first protrusions 1663ct. By arranging the multiple first protrusions 1663ct to satisfy this condition, the multiple first protrusions 1663dt can rotate in mesh with the first main gear portion 81c in a backlash-free state and receive the driving force FB.

[0205] The second gear portion (second unit side gear portion, second unit side helical gear portion) 1663d includes a plurality of cylindrical second protrusions 1663dt that protrude in the radial direction centered on the rotation axis L1. The second gear portion 1663d is a rotating portion that rotates integrally with the first gear portion 1663c. The multiple second protrusions 1663dt are arranged at offset positions with respect to the direction of the rotation axis L1.

[0206] Furthermore, when viewed along the rotation axis L1, the tips S of the multiple second protrusions 1663dt (see FIG. 42(a)) are arranged on a predetermined circumference centered on the rotation axis L1. The multiple second protrusions 1663dt are protrusions with a width in the direction of the rotation axis L1 and the rotation direction (direction I) that is large enough to be inserted between the teeth (valley portions) of the second main gear portion 81d of the drive transmission gear 81. The multiple second protrusions 1663dt are arranged at positions that allow them to be inserted between the teeth (valley portions) of the second main gear portion 81d of the drive transmission gear 81 and receive the restraining force FB from the second main gear portion 81d in a backlash-free state. Specifically, as shown in FIG. 48(a), multiple imaginary twist lines (spiral lines) L14 twisted at the same angle as the twist angle α2 of the second main gear portion 81d are drawn at a predetermined pitch P10 on a cylindrical surface centered on the rotation axis L1. This pitch P10 is the same as the pitch in a direction perpendicular to the tooth surfaces of the multiple second helical teeth 81dt of the second main gear portion 81d of the drive transmission gear 81. The multiple second protrusions 1663dt are arranged so as to satisfy the following condition in relation to the multiple torsion lines L14: some of the multiple torsion lines L14 must be in contact with some of the multiple second protrusions 1663dt, and none of the multiple torsion lines L14 must pass through the cross section of the multiple second protrusions 1663dt. By arranging the multiple second protrusions 1663dt to satisfy this condition, the multiple second protrusions 1663dt can perform the same function as the multiple second protrusions 1363dt of Example 13, that is, they rotate in mesh with the second main gear portion 81d in a backlash-free state and receive the restraining force FB.

[0207] As shown in FIG. 48(b), when the drive transmission gear 81 is driven, it moves in the J direction, similar to the first embodiment. This is because the first main body gear portion 81c comes into contact with the multiple first protrusions 1663ct and receives a thrust force in the J direction. As the drive transmission gear 81 moves in the J direction, the upstream surface 81d2 of the second main body gear portion 81d in the I direction eventually comes into contact with the contact portion CP2 of the second protrusion 1663dt of the second gear portion 1663d, and receives a thrust force F1610 in the H direction. In addition, the downstream surface 81c1 of the first main body gear portion 81c in the I direction comes into contact with the contact portion CP1 of the first protrusion 1663ct of the first gear portion 1663c, and receives a thrust force F1609 in the J direction. Therefore, the drive transmission gear 81 is positioned at a balanced position using the same principle as the first embodiment, and a backlash-free state is achieved. In addition, in the backlash-free state, with respect to driving in the rotational direction, the first gear portion 1663c receives a driving force FD, and the second gear portion 1663d receives a restricting force FB at the contact portion CP of the second protrusion 1463dt.

[0208] The first gear portion 1663c can be considered a type of gear (helical gear) by using the multiple first protrusions 1663ct to mesh with other gears such as the first main body gear portion 81d and receive rotational driving force and / or thrust force. In other words, the surfaces of the multiple first protrusions 1663ct (multiple contact portions CP1) can be said to form a helical surface divided into multiple parts in the direction of the rotation axis L1, or to form a helical surface divided into multiple parts in the circumferential direction around the rotation axis L1 of the drive-side flange 1663.

[0209] Therefore, by connecting the multiple contact portions CP1, a twist line L15 can be defined. The multiple first protrusions 1663ct are arranged so that they can each contact one tooth of the first main body gear portion 81c at multiple locations that are spaced apart in the direction of the rotation axis L1. It can also be said that the multiple contact portions CP1 that can simultaneously contact one tooth of the first main body gear portion 81c are provided at locations that are spaced apart in the direction of the rotation axis L1. In this way, it can be said that the multiple first protrusions 1663ct that are spaced apart in the direction of the rotation axis L1 form one tooth (helical tooth) that meshes with one tooth of the first main body gear portion 81c. Therefore, the multiple first protrusions 1663ct function as a helical gear, and the first gear portion 1663c is a first helical gear portion.

[0210] Furthermore, the circle drawn as the rotation trajectory when the tip (point) among the tips of the multiple first protrusions 1663ct that is farthest from the rotation axis L1 rotates is defined as the tooth tip circle of the first gear portion 1663c, and the diameter of that circle is defined as the tooth tip circle diameter.

[0211] Similarly, the second gear portion 1663d can be considered a type of gear because it can use the multiple second protrusions 1663dt to mesh with other gears such as the second main body gear portion 81d and receive rotational driving force and / or thrust force. In other words, the surfaces of the multiple second protrusions 1663dt (multiple contact portions CP2) can be said to form a helical tooth surface divided into multiple parts in the direction of the rotation axis L1, or to form a helical tooth surface divided into multiple parts in the circumferential direction around the rotation axis L1 of the drive-side flange 1663.

[0212] Therefore, by connecting the multiple contact portions CP2, a twist line L14 can be defined. The multiple second protrusions 1663dt are arranged so that they can each contact one tooth of the second main body gear portion 81d at multiple locations spaced apart in the direction of the rotation axis L1. In other words, the multiple contact portions CP2 that can simultaneously contact one tooth of the second main body gear portion 81d are provided at locations spaced apart in the direction of the rotation axis L1. In this way, the multiple second protrusions 1663dt arranged separately in the direction of the rotation axis L1 can be said to form one tooth (helical tooth) that meshes with one tooth of the second main body gear portion 81d. Therefore, the multiple second protrusions 1663dt function as a helical gear, and the second gear portion 1663d is a second helical gear portion.

[0213] Furthermore, the circle drawn as the rotation trajectory when the tip (point) among the tips of the multiple second protrusions 1663dt that is farthest from the rotation axis L1 rotates is defined as the tooth tip circle of the second gear portion 1663d, and the diameter of that circle is defined as the tooth tip circle diameter.

[0214] Furthermore, each of the multiple first protrusions 1663ct and the multiple second protrusions 1663dt is not limited to a cylindrical shape, but may have a shape that protrudes at least in the radial direction centered on the rotation axis L1. Furthermore, the multiple first protrusions 1663ct do not have to be completely separated protrusions while having multiple contact portions CP1. For example, they may have a partially connected shape such that the cross section in the tangential direction perpendicular to the radial direction centered on the rotation axis L1 has a stepped shape. The same applies to the multiple second protrusions 1663dt. Furthermore, all of the multiple first protrusions 1663ct do not have to have the same shape, and all of the multiple second protrusions 1663dt do not have to have the same shape.

[0215] [Example 17] Example 17 differs from Example 1 in the following respects. First, the layout of each component within the main assembly A of the apparatus into which cartridge B is mounted is different. As a result, the orientation of cartridge B within the main assembly A of the apparatus is different. Furthermore, the support configuration of the drive-side flange 1763 and the engagement configuration between the drive transmission gear 1781 and the idler gear 1780 are different. The drive transmission configuration to the developing roller 1732 is the same as that of the <Other Modifications> of Example 1. The axial positional relationship between the first gear portion receiving the drive force FD and the second gear portion receiving the regulating force FB is the same as that of Example 9. Other points are the same as those of Example 1, and detailed descriptions will be omitted. Furthermore, among the elements of this example, elements (e.g., drum 1762) corresponding to elements of Example 1 (e.g., drum 62) are assigned the reference numerals associated with the corresponding elements of Example 1 (e.g., "1762" corresponding to "62"). Regarding these elements, matters that are not specifically described are the same as the corresponding elements of Example 1.

[0216] <Device configuration> 50 is a cross-sectional view (the cross section is perpendicular to the rotation axis L1) of the apparatus main body A with the cartridge B installed. The apparatus main body A of the image forming apparatus 17100 has an exposure device (laser scanner unit) 1703 and a sheet tray 1704 that stores sheet material PA. Furthermore, the apparatus main body A has a pickup roller (not shown), a pair of conveying rollers 1705b, a transfer guide 1706, a transfer roller 1707, a conveying guide 1708, a fixing device 1709, a pair of discharge rollers 1710, and a discharge tray 1711 along the conveying path of the sheet material PA.

[0217] <Posture of cartridge B inside device main body A> 50, the cartridge B is positioned inside the apparatus main body A with the cleaning unit 1760 and the developing unit 1720 aligned almost horizontally. At this time, the transfer roller 1707 is disposed below the drum 1762.

[0218] <Support structure of drum unit 1769 by cleaning unit 1760> Next, the support structure of the drum unit 1769 by the cleaning unit 1760 will be described with reference to Figures 51(a), 51(b), 52(a), 52(b), 52(c), 58 and 59.

[0219] FIG. 51(a) is an exploded perspective view of the cleaning unit 1760, showing the cleaning unit 1760 as viewed from the development unit side, with the inside of the drum bearing member 1773 visible. FIG. 51(b) is an exploded perspective view of the cleaning unit 1760, showing the cleaning unit 1760 as viewed from the development unit side, with the outside of the drum bearing member 1773 visible. FIG. 52(a) is a perspective view of the drum bearing member 1773 as viewed from the inside. FIG. 52(b) is a cross-sectional view of the guided portion 1773g of the drum bearing member 1773 that supports the drive-side flange 1763, taken along a plane perpendicular to the rotation axis L1. Note that this cross-sectional view shows the cross-section as viewed from the inside of the drum bearing member 1773. FIG. 52(c) is a cross-sectional view of the vicinity of the drive-side flange 1763 of cartridge B installed in the main assembly A of the apparatus, taken along a plane that includes the rotation axis L1 and is perpendicular to the installation direction M of cartridge B into the main assembly A of the apparatus (see FIG. 57). Figure 58 shows a cross section of the cleaning unit 1760 and the drive transmission gear 1781 as seen from the outside of the drum bearing member 1773, and the cross section is a cross section that passes through the hole 1773d of the drum bearing member 1773 that supports the drive side flange 1763 and is perpendicular to the rotation axis L1. Figure 59 is a partial perspective view of the vicinity of the drive side flange 1763 of the cartridge B.

[0220] As shown in Figures 51(a) and 51(b), the cleaning unit 1760 has a frame member 1771 and a drum bearing member 1773 fixed thereto, which together form a drum frame that supports the drum 1762. The drive-side flange 1763 is provided with a cylindrical protrusion (supported portion) 1763g centered on the rotation axis L1, which is provided outward (downstream in the J direction) from the end of the drive-side flange 1763 with respect to the rotation axis L1 and protrudes downstream in the J direction from the end of the drive-side flange 1763. The drum bearing member 1773 is provided with a hole 1773d recessed in the direction of the rotation axis L1 (direction J) to support the protrusion 1763g. As shown in FIGS. 52(a) and 52(b), the inner peripheral surface of the hole 1773d has two flat surfaces 1773e and 1773f and two circumferential surfaces 1773h and 1773i, each parallel to the rotation axis L1. The two flat surfaces 1773e and 1773f are not parallel to each other but are arranged to form a generally V-shaped recess when viewed from the direction of the rotation axis L1. The flat surfaces 1773e and 1773f are support surfaces (support portions) that have support points that contact and support the protrusion 1763g. As shown in FIG. 58, the generally V-shaped recess formed by the two flat surfaces 1773e and 1773f is oriented in a direction opposite to a force FH that is parallel to the force FG originating from the rotation axis L1 so as to be able to withstand the meshing force FG between the gear teeth when the driving force is transmitted from the drive transmission gear 1781 to the drive-side flange 1763. Specifically, the force FH is set so as to be substantially parallel to the bisector of the angle formed by the extension line of the plane 1773e and the extension line of the plane 1773f when viewed along the rotation axis L1. Note that the orientation of the two planes 1773e and 1773f is not limited to this, and may be set by comprehensively taking into account various forces that apply a load to the drive-side flange 1763.

[0221] After the drum unit 1769 is assembled inside the frame member 1771, the drum bearing member 1773 is attached and fixed to the frame member 1771, whereby the protrusion 1763g of the drive-side flange 1763 fits into the hole 1773d of the drum bearing member 1773. This allows the drum unit 1769 to be rotatably supported by the frame member 1771 and the drum bearing member 1773. As shown in Figures 59 and 114(b), in the completed cartridge B, part of the drive-side flange 1763 (part of the first gear portion 1363c and part of the second gear portion 1363d) and part of the drum 1762 are not covered by the drum frame (drum bearing member 1773 and frame member 1771) and are exposed to the outside of the cartridge B. In other words, the drum frame has openings for exposing part of the drive side flange 1763 (part of the first gear portion 1363c and part of the second gear portion 1363d, etc.) and part of the drum 1762 to the outside.

[0222] As shown in Figure 52(c), when cartridge B is mounted in the apparatus main assembly A, the arcuate surface of the guided portion 1773g contacts the two positioning portions 1715a of the first drive-side side plate 1715 of the apparatus main assembly A, and the position of the rotational axis L1 of cartridge B relative to the apparatus main assembly A is determined in two directions perpendicular to the rotational axis L1 (mounting direction M and orthogonal direction MP perpendicular to mounting direction M) (see Figure 57). The guided portion 1773g is a protrusion that protrudes outward (in the J direction) in the direction of the rotational axis L1, and the above-mentioned hole 1773d is formed inside the guided portion 1773g. The apparatus main assembly A is provided with a pressing member (not shown) that presses cartridge B so as to press the guided portion 1773g toward the two positioning portions 1715a. In addition, the meshing force FG between the gear teeth when the driving force is transmitted from the drive transmission gear 1781 to the driving-side flange 1763 acts to press the guided portion 1773g toward the two positioning portions 1715a. Furthermore, the force with which the transfer roller 1707 (see FIG. 50) presses the drum 1762 also acts to press the guided portion 1773g toward the positioning portions 1715a in the orthogonal direction MP.

[0223] At least a portion of the guided portion 1773g, at least a portion of the two flat portions 1773f and 1773e, and at least a portion of the protrusion 1763g are arranged in the same position in the direction of the rotation axis L1. In other words, at least a portion of the guided portion 1773g, at least a portion of the two flat portions 1773f and 1773e, and at least a portion of the protrusion 1763g are arranged on a single plane perpendicular to the rotation axis L1. This arrangement suppresses deformation of the drum bearing 1773 that would cause it to tilt with respect to the rotation axis L1, and suppresses tilt (tilting) of the drive-side flange 1763 with respect to the rotation axis L1. As a result, deterioration in the meshing accuracy between the drive-side flange 1763 and the drive transmission gear 1781 can be suppressed. Furthermore, by abutting the protrusion 1763g against the two flat surfaces 1773f, 1773e, the fit play can be shifted in one direction (along the bisector of the angle formed by the extension line of the flat surface 1773e and the extension line of the flat surface 1773f when viewed along the rotation axis L1), thereby improving the positional accuracy of the drive side flange 1763 in a direction perpendicular to the rotation axis L1 and suppressing deterioration in the meshing accuracy with the drive transmission gear 1781.

[0224] In this embodiment, the protrusion 1763g is formed integrally with the driving side flange 1763, but the protrusion 1763g may be formed from a separate part such as metal and press-fitted into the driving side flange 1763.

[0225] Next, the axial positioning of the drive-side flange 1763 will be described. As shown in FIGS. 51(a) and 51(b), the first gear portion 1763c of the drive-side flange 1763 has a protrusion 1763c1 that protrudes slightly in the H direction on its end surface on the downstream side in the H direction, and a protrusion 1763f that protrudes slightly in the J direction on its end surface on the downstream side in the J direction (upstream side in the H direction). The frame member 1771 also has a rib 1771p and a side wall 1771m that extend in a direction perpendicular to the rotation axis L1. The protrusion 1763c1 is capable of contacting the side surface of the rib 1771p, and the protrusion 1763f is capable of contacting the side surface of the side wall 1771m. The drive-side flange 1763 is loosely fitted and held between the rib 1771p and the side wall 1771m so as to be slidable in the direction of the rotation axis L1. As a result, the driving side flange 1763 is positioned relative to the frame member 1771 in relation to the direction of the rotation axis L1, and as a result, the position of the drum unit 1769 within the frame member 1771 is determined.

[0226] <Installation, removal and positioning of cartridge B in apparatus main body A> FIG. 113(a) is a view of the cartridge B installed in the apparatus main assembly A installed on a horizontal installation surface, viewed in the direction (K direction) along the rotation axis L1. The horizontal direction is indicated as HD, and the vertical direction is indicated as VD. A plane perpendicular to the rotation axis L1 is parallel to the vertical direction VD. FIG. 113(b) is a view of the cartridge B viewed in the HD1 direction, which is parallel to the horizontal direction HD shown in FIG. 113(a). FIG. 114(a) is a view of the cartridge B viewed in the VD1 direction, which is parallel to the vertical direction VD shown in FIG. 113(a). FIG. 114(b) is a view of the cartridge B viewed in the VD2 direction, which is parallel to the vertical direction VD shown in FIG. 113(a). When viewed along the rotation axis L1, as can be seen from FIG. 50, the installation direction M is substantially parallel to the straight line connecting the rotation center of the developing roller 1732 and the rotation center (rotation axis L1) of the photosensitive drum 1762. Therefore, the mounting direction M in the following description can be interpreted as a direction perpendicular to the rotation axis L1 and parallel to the line connecting the rotation center of the developing roller 1732 and the rotation center of the photosensitive drum 1762 (rotation axis L1).

[0227] As in the first embodiment, the mounting direction M of the cartridge B to the main assembly A of the apparatus and the removal direction (the opposite direction to the mounting direction M) from the main assembly A of the apparatus are substantially perpendicular to the rotation axis L1. The mounting direction of the drum unit 69 to the main assembly A of the apparatus and the removal direction from the main assembly A of the apparatus are the same as the mounting direction M of the cartridge B to the main assembly A of the apparatus and the removal direction from the main assembly A of the apparatus, respectively.

[0228] As shown in FIG. 113(a), the drum bearing member 1773 is provided with guided portions 1773s1, 1773s2, and 1773s3 in addition to the guided portion 1773g described above. These guided portions are protrusions that protrude from the main body of the drum bearing member 1773 in the direction of the rotation axis L1. When the cartridge B is mounted in or removed from the apparatus main body A, it comes into contact with and is guided by a guide portion (not shown) provided in the apparatus main body A. As shown in other figures, the guided portion 1773s1 can be omitted. The guided portion 1773s3 can also be omitted if necessary. However, providing the guided portions 1773s1 and 1773s3 makes the mounting and removal of the cartridge B more stable. Furthermore, the guided portion 1773s1 is a protrusion that is long in the mounting direction M (or long along a direction perpendicular to the rotation axis L1 and parallel to the line connecting the rotation center of the developing roller 1732 and the rotation center (rotation axis L1) of the photosensitive drum 1762). Making the guided portion 1773s1 such a long protrusion increases the rigidity of the drum bearing member 1773. Furthermore, although the guided portion 1773s1 and the guided portion 1773g are provided as a single connected protrusion, they may also be provided as separate protrusions. However, providing them as a single connected protrusion increases the rigidity of the drum bearing member 1773.

[0229] Furthermore, as described above, when cartridge B is mounted in the apparatus main assembly A, the guided portion 1773g comes into contact with the two positioning portions 1715a of the apparatus main assembly A, and the position of the rotation axis L1 of cartridge B relative to the apparatus main assembly A is determined in two directions perpendicular to the rotation axis L1 (mounting direction M and perpendicular direction MP) (see Figures 52(c) and 57). Furthermore, when the guided portion 1773s2 comes into contact with positioning portions of the apparatus main assembly A (not shown), the position (posture) of cartridge B relative to the apparatus main assembly A is determined in the rotation direction around the rotation axis L1.

[0230] Further, the positioning of the cartridge B relative to the apparatus main assembly A in the direction of the rotation axis L1 is the same as in Example 1. Specifically, as shown in Figure 113(b) and Figure 114(a), the drum bearing member 1773 has a fitted portion 1773h having a concave shape recessed along the mounting direction M, into which a fitting portion having a convex shape protruding along the mounting direction M (not shown) of the apparatus main assembly A is fitted, thereby determining the position of the cartridge B relative to the apparatus main assembly A in the direction of the rotation axis L1.

[0231] As shown in FIG. 113(a), the drum bearing member 1773 has a developing unit support portion 1773b having a substantially cylindrical surface extending in the direction of the rotation axis L1. The developing unit support portion 1773b supports a cylindrical portion 1721a, which is disposed so as to surround the developing coupling member 1789 and the coupling portion 1789a of the frame 1721 of the developing unit 1720, so that the developing unit 1720 can rotate (swing) about a rotation axis DA. The rotation axis DA is coaxial with the rotation axis of the developing coupling member 1789 and is parallel to the rotation axis L1. The developing unit 1720 can rotate (swing) in the direction DS about the rotation axis DA relative to the cleaning unit 1760 by receiving a force from a force applying portion (not shown) of the apparatus main body A at the force receiving portion 1721b of the frame 1721 of the developing unit 1720. This rotation allows the developing roller 1732 to be separated from the drum 1762.

[0232] Furthermore, as shown in FIG. 113(a), when viewing the cartridge B from the direction of the rotational axis L1, the guided portion 1773s2 is disposed on a straight line LT passing through the rotational axis L1 and the pivot axis DA, and the developing unit support portion 1773b and the pivot axis DA are disposed between the rotational axis L1 and the guided portion 1773s2 in the direction parallel to the straight line LT. This allows the cleaning unit 1760 to firmly support the relatively heavy developing unit 1760. Therefore, it can be said that the developing unit support portion 1773b and the pivot axis DA are disposed between the rotational axis L1 and the guided portion 1773s2 in all directions, including the mounting direction M (or the longitudinal direction of the guided portion 1773s1), the orthogonal direction MP perpendicular to the mounting direction M (or the direction perpendicular to the longitudinal direction of the guided portion 1773s1), the horizontal direction HD, and the vertical direction VD.

[0233] Furthermore, when cartridge B is viewed from the direction of rotation axis L1, and the area is divided by a straight line LT, guided portion 1773s1 is located in one area, and guided portion 1773s3 is located in the other area, so that the posture of cartridge B is stable during installation and removal.

[0234] 113(b), 114(a), and 114(b), the drum frame of the cleaning unit 1760 has, in addition to the drum bearing member (first bearing member) 1773 and frame member 1711 described above, a non-drive-side drum bearing member (second bearing member) 1712 attached to the frame member 1711. As described above, the drive-side flange 1763 (first flange member) of the drum unit 1769 is rotatably supported by the drum bearing member 1773. On the other hand, the non-drive-side flange (second flange member) 1764 of the drum unit 1769 is rotatably supported by the non-drive-side drum bearing member 1712. The non-drive-side flange 1764 is a member fixed to the downstream end of the drum 1762 in the H direction. In other words, the drum bearing member (first bearing member) 1773 is disposed at the first end of the drum frame in the direction of the rotation axis L1, and the non-drive-side drum bearing member (second bearing member) 1712 is disposed at the second end of the frame opposite the first end of the frame. Of the two ends of the drum 62 in the direction of the rotation axis L1, the photosensitive element first end is disposed closer to the first end of the frame than the second end of the frame, and the photosensitive element second end opposite the first end of the photosensitive element is disposed closer to the second end of the frame than the first end of the frame. As can be seen from Figures 114(a) and 114(b), the non-drive-side drum bearing member 1712 has a protruding portion 1712a that protrudes downstream in the installation direction M. As can be seen from FIG. 50, when viewed along the direction of the rotation axis L1, a line connecting the rotation center of the developing roller 1732 and the rotation center of the photosensitive drum 1762 (rotation axis L1) is substantially parallel to the mounting direction M. Therefore, the protruding portion 1712a is perpendicular to the rotation axis L1 and protrudes downstream of the drum bearing member 1773 or the drum 1762 in the direction from the rotation center of the developing roller 1732 to the rotation center of the photosensitive drum 1762 (a direction substantially parallel to the mounting direction M). A memory board 1740 mounting a nonvolatile memory chip is attached to the protruding portion 1712a. The memory board 1740 is electrically connected to the nonvolatile memory chip and includes an electrode portion (electrode surface) 1740a, which is a surface that is in contact with and can be electrically connected to a main body electrode portion (not shown) of the apparatus main body A.The electrode portion 1740a is disposed near an end (first frame end) on the side (drive side) where the drum bearing member 1773 and the drive-side flange 1763 are disposed, and near an end (second frame end) on the opposite side (non-drive side) with respect to the direction of the rotation axis L1. Specifically, the region where the electrode portion 1740a is disposed with respect to the direction of the rotation axis L1 is a region that includes the downstream end of the drum 1762 in the H direction (second end of the photosensitive member). However, with respect to the direction of the rotation axis L1, the region where the electrode portion 1740a is disposed may be disposed at a position (a downstream position in the H direction) closer to the outside of the drum frame (or the outside of the cartridge B) than the downstream end of the drum 1762 in the H direction (second end of the photosensitive member). Furthermore, with respect to the direction of the rotation axis L1, the region where the electrode portion 1740a is disposed and the region where the non-drive-side flange 1764 is disposed are at least partially in the same position (at least partially overlapping). However, with respect to the direction of the rotation axis L1, the region where the electrode portion 1740a is arranged may be located closer to the outside of the drum frame (or the outside of the cartridge B) than the region where the non-drive-side flange 1764 is arranged (a downstream position in the direction H). Furthermore, the electrode portion 1740a is located downstream of the rotation axis L1 and the photosensitive drum 1762 with respect to the mounting direction M. Furthermore, the electrode portion 1740a is located downstream of the rotation axis L1 or the photosensitive drum 1762 with respect to a direction perpendicular to the rotation axis L1 and extending from the center of rotation of the developing roller 1732 toward the center of rotation of the photosensitive drum 1762 (a direction substantially parallel to the mounting direction M). Furthermore, the memory board 1740 is supported by the cleaning unit 1760 with the electrode portion (electrode surface) 1740a oriented perpendicular to the mounting direction M.

[0235] <Drive side flange 1763> Next, the drive side flange 1763 will be described using Figures 54(b) and 60. Figure 54(b) is a schematic cross-sectional view of the gear portion of the drive side flange 1763. This cross-section is tangent to the meshing pitch circle when meshing with the drive transmission gear 1781. Figures 60(a) and (b) are cross-sectional views of the vicinity of the drive side flange 1763 of the drum unit 1769, and this cross-section includes the rotation axis L1.

[0236] The drive-side flange 1763 is coaxially equipped with a first gear portion (first unit side gear portion, first unit side helical gear portion) 1763c and a second gear portion (second unit side gear portion, second unit side helical gear portion) 1763d as helical gear portions. The first gear portion 1763c is disposed upstream of the second gear portion 1763d in the H direction (downstream in the J direction). In other words, the second gear portion 1763d is disposed between the first gear portion 1763c and the drum 1762 in the direction of the rotation axis L1. The first gear portion 1763c includes a plurality of first helical teeth (teeth, first protrusions) 1763ct arranged at different positions in the circumferential direction about the rotation axis L1, and the second gear portion 1763d includes a plurality of second helical teeth (teeth, second protrusions) 1763dt arranged at different positions in the circumferential direction about the rotation axis L1. The first helical teeth 1763ct and the second helical teeth 1763dt are both involute tooth-shaped teeth and protrusions that protrude radially from the rotation axis L1. The first gear portion 1763c and the second gear portion 1763d are integrally molded from resin and rotate integrally. Therefore, the first gear portion 1763c and the second gear portion 1763d can also be considered as a first rotating portion and a second rotating portion that rotate integrally with each other. The first gear portion 1763c meshes with the first main body gear portion 1781c of the drive transmission gear 1781, and the second gear portion 1763d meshes with the second main body gear portion 1781d of the drive transmission gear 1781.

[0237] The twist directions of the first gear portion 1763c and the second gear portion 1763d of the drive-side flange 1763 are the same, and are such that the tooth surfaces are displaced in the K direction as they move in the J direction. The twist directions of the first gear portion 1763c and the second gear portion 1763d are opposite to the twist directions of the first main body gear portion 1781c and the second main body gear portion 1781d of the drive transmission gear 1781. As in the first embodiment, the twist angle of the second gear portion 1763d is larger than the twist angle of the first gear portion 1763c. The twist angle of the first gear portion 1763c is the same as the twist angle of the first main body gear portion 1781c, which will be described later, and the twist angle of the second gear portion 1763d is the same as the twist angle of the second main body gear portion 1781d, which will be described later. Furthermore, the first gear portion 1763c and the second gear portion 1763d of the driving side flange 1763 have the same number of teeth.

[0238] 60(a), the width (tooth width) Wc of the first helical teeth (teeth, first protrusions) 1763ct in the direction of the rotation axis L1 is larger than the width (tooth width) Wd of the second helical teeth (teeth, second protrusions) 1763dt in the direction of the rotation axis L1. In other words, each of the first gear portion 1763c and the second gear portion 1763d has at least one tooth such that the face width Wc of the first helical teeth (teeth, first protrusions) 1763ct and the face width Wd of the second helical teeth (teeth, second protrusions) 1763dt in the direction of the rotation axis L1 satisfy the following formula A1. Wc>Wd (Eq. A1)

[0239] While the drive side flange 1763 is being driven by the drive transmission gear 1781 in a balanced state, the driving force FD received by the first gear portion 1763c is greater than the regulating force FB received by the second gear portion 1763d, so such a relationship is preferable.

[0240] Furthermore, the larger the meshing width (meshing width) of the rotation axis L1 of the meshing (contact) portion of the first gear portion 1763c with the first main body gear portion 1781c and the meshing width of the second helical gear portion 1763c with the second main body gear portion 1781d, the better the drive transmission accuracy. However, if the meshing width is set larger than necessary, the widths of the first gear portion 1763c and the second gear portion 1763c in the direction of the rotation axis L1 will increase, resulting in an increase in the size of the drive-side flange 1763, the drum unit 1769, the cartridge B, and ultimately the apparatus main body A. Therefore, it is preferable that the tooth width Wc1 of the first helical tooth (tooth) 1763ct, which has the widest tooth width in the first gear portion 1763c, and the tooth width Wd1 of the second helical tooth (tooth) 1763dt, which has the widest tooth width in the second gear portion 1763d, satisfy the following formula A2, and more preferably formula A3. Wd1≦(4 / 5)·Wc1···(Formula A2) Wd1≦(3 / 4)·Wc1···(Formula A3)

[0241] Furthermore, from the viewpoint of the strength of the second helical tooth (tooth) 1763dt of the second gear portion 1763d, it is preferable that the second helical tooth (tooth) 1763dt have a certain degree of tooth width or more, and it is preferable that the tooth width Wc1 and the tooth width Wd1 satisfy the following formula A4. Wd1≧(1 / 10)·Wc1···(Formula A4)

[0242] Furthermore, the width (length) We of the cylindrical portion 1763e (or gap g) in the direction of the rotation axis L1 is set to satisfy the following equations B1, B2, and B3, as in Example 1, when the widths Wc and Wd are used as references.

[0243] If the tooth width Wc of the first gear portion 1763c is not constant, the tooth width Wc1 of the tooth with the widest tooth width is defined as the tooth width Wc. We≧Wc / 5...(Formula B1) We≦Wc...(Formula B2) We≦Wd (Equation B3)

[0244] In this embodiment, the tooth widths of all the teeth of the first gear portion 1763c are the same, and the tooth widths of all the teeth of the second gear portion 1763c are also the same, with tooth width Wc set to 8.2 mm, tooth width Wd set to 5.2 mm, and width We set to 3.1 mm.

[0245] 60(b), the meshing pitch circle diameters D63c and D63d of the first gear portion 1763c and the second gear portion 1763d are set to be approximately the same when the drive-side flange 1763 and the drive transmission gear 1781 mesh. Similarly, the meshing pitch circle diameters of the first main body gear portion 1781c and the second main body gear portion 1781d are set to be approximately the same. This allows the meshing of the first gear portion 1763c and the first main body gear portion 1781c, and the meshing of the second gear portion 1763d and the second main body gear portion 1781d to be properly achieved without tooth tip contact.

[0246] Furthermore, as in Example 1, the tooth tip circle diameter Dt63c of the first gear portion 1763c and the tooth root circle diameter Db63d of the second gear portion 1763d are set to be approximately the same so that the meshing between the first main body gear portion 1781c and the second main body gear portion 1781d is proper without contact at the tooth tips.

[0247] Specifically, it is preferable that the size of the tip diameter Dt63c of the first gear portion 1763c be set to a value larger than the root diameter Db63d of the second gear portion 1763d, or to a value larger than 0.8 times (more preferably 0.9 times) the tip diameter Dt63d of the second gear portion 1763d. Also, it is preferable that the size of the tip diameter Dt63c of the first gear portion 1763c be set to a value smaller than 1.1 times the tip diameter Dt63d of the second gear portion 1763d.

[0248] Furthermore, it is preferable that the size of the root circle diameter Db63c of the first gear portion 1763c be set to a value smaller than the tip circle diameter Dt63d of the second gear portion 1763d, and that the size of the root circle diameter Db63c of the first gear portion 1763c be set to a value larger than 0.9 times the root circle diameter Db63d of the second gear portion 1763d.

[0249] Furthermore, it is preferable that the size of the tip circle diameter Dt63d of the second gear portion 1763d be set to a value larger than the root circle diameter Db63c of the first gear portion 1763c or a value larger than 0.8 times (more preferably 0.9 times) the tip circle diameter Dt63c of the first gear portion 1763c. It is also preferable that the size of the tip circle diameter Dt63d of the second gear portion 1763d be set to a value smaller than 1.1 times the tip circle diameter Dt63c of the first gear portion 1763c.

[0250] Furthermore, it is preferable that the size of the root circle diameter Db63d of the second gear portion 1763d be set to a value smaller than the tip circle diameter Dt63c of the first gear portion 1763c. Also, it is preferable that the size of the root circle diameter Db63d of the second gear portion 1763d be set to a value larger than 0.9 times the root circle diameter Db63c of the first gear portion 1763c.

[0251] In this embodiment, the tip diameter Dt63c, pitch diameter D63c, and root diameter Db63c of the first gear portion 1763c were set to 22.3 mm, 21.1 mm, and 19.6 mm, respectively. The tip diameter Dt63d, pitch diameter D63d, and root diameter Db63d of the second gear portion 1763d were set to 22.1 mm, 21.1 mm, and 19.8 mm, respectively. The diameter of the cylindrical portion 1763e was set to 17.5 mm.

[0252] Also, the modules are made different between the first gear portion 1763c and the second gear portion 1763d and the displacement amounts are changed so that the meshing pitch circle diameters D63c and D63d are the same while the helix angles of the first gear portion 1763c and the second gear portion 1763d are made different. Similarly, the modules of the first main body gear portion 1781c and the second main body gear portion 1781d of the drive transmission gear 1781 are made different and the displacement amounts are changed.

[0253] The driving-side flange 1763 also includes a cylindrical portion (intermediate portion, small-diameter portion, shaft portion) 1763e between the first gear portion 1763c and the second gear portion 1763d in the direction of the rotation axis L1. The cylindrical portion 1763e has a maximum diameter D63e centered on the rotation axis L1 that is smaller than the tip circle diameter Dt63c of the first gear portion 1763c and the tip circle diameter Dt63d of the second gear portion 1763d. Furthermore, in this embodiment, the maximum diameter D63e of the cylindrical portion 1763e centered on the rotation axis L1 is smaller than the root circle diameter Db63c of the first gear portion 1763c and the root circle diameter Db63d of the second gear portion 1763d. However, the maximum diameter D63e of the cylindrical portion 1763e about the rotation axis L1 is not limited to the above as long as the maximum diameter D63e does not come into contact with the drive transmission gear 1781 while the drive side flange 1763 is being driven by the drive transmission gear 1781. As will be described later in Examples 22 and 23, the distance (radius) R63e from the rotation axis L1 to the outer diameter of the cylindrical portion 1763e may be configured to be at least temporarily smaller than the tip circle radius Rt63ct of the first gear portion 1763c or the tip circle radius Rt63d of the second gear portion 1763d so that the drive side flange 1763 and the drive transmission gear 1781 can mesh to transmit driving force, as will be described later in Examples 22 and 23.

[0254] Where the relationship between these dimensions is shown using the various diameters of the first gear portion 1763c, the second gear portion 1763d, and the cylindrical portion 1763e, it is obvious that the same relationship will be obtained even if the diameters are replaced with radii.

[0255] <Drive transmission gear 1781> Next, the drive transmission gear 1781 of the device main body A, which meshes with the drive side flange 1763, will be described using Figures 53 and 54(a). Figures 53(a) and (b) are exploded perspective views of the drive transmission gear 1781 and its surroundings of the device main body A, with (a) showing the state as seen from the second drive side side plate 1783 side and (b) showing the state as seen from the main frame 1784 side. Figure 54(a) is a schematic cross-sectional view of the gear portion of the drive transmission gear 1781. The cross-section is tangent to the meshing pitch circle when meshing with the drive side flange 1763.

[0256] The drive transmission gear 1781 includes a first main body gear portion (first main body helical gear portion) 1781c and a second main body gear portion (second main body helical gear portion) 1781d, which are coaxially arranged as helical gear portions. The first main body gear portion 1781c is disposed upstream of the second main body gear portion 1781d in the H direction (downstream in the J direction). The first main body gear portion 1781c includes a plurality of first main body helical teeth 1781ct, and the second main body gear portion 1781d includes a plurality of second main body helical teeth 1781dt. Both the first main body helical teeth 1781ct and the second main body helical teeth 1781dt are involute tooth teeth. The first main body gear portion 1781c and the second main body gear portion 1781d are integrally molded from resin and rotate integrally. The first main body gear portion 81c and the second main body gear portion 81d are twisted in the same direction such that the tooth surfaces are displaced in the I direction as they move in the J direction. As in the first embodiment, the twist angle of the second main body gear portion 1781d is larger than the twist angle of the first main body gear portion 1781c. The first main body gear portion 81c and the second main body gear portion 81d have the same number of teeth. When the cartridge B is attached to the apparatus main body A, the first gear portion 1763c meshes with the first main body gear portion 1781c, and the second gear portion 1763c meshes with the second main body gear portion 1781d.

[0257] FIG. 112 is a perspective view of another example of the drive transmission gear 1781. As shown in FIG. 112, a rib-shaped portion (protruding portion, radially protruding main portion) 1781p protruding in a radial direction about the rotation axis L2 may be provided between the first main body gear portion 1781c and the second main body gear portion 1781d in the direction of the rotation axis L2. Depending on the manufacturing method of the drive transmission gear 1781, providing the rib-shaped portion 1781p may improve or prevent deterioration of molding accuracy and reduce manufacturing costs. The diameter of the rib-shaped portion 1781p is approximately the same as the tip diameter of the first main body gear portion 1781c and the tip diameter of the second main body gear portion 1781d. The rib-shaped portion 1781p may be provided over the entire circumference or only a portion of the circumference in the circumferential direction about the rotation axis L2. Here, the driving-side flange 1763 is provided with a cylindrical portion 1763e, and thus a gap g (see FIG. 60, etc.) is formed between the first gear portion 1763c and the second gear portion 1763d in the direction of the rotation axis L1. Due to the presence of this gap g, even if the drive transmission gear 1781 has a rib-shaped portion 1781p, the rib-shaped portion 1781p and the driving-side flange 1763 are prevented from coming into contact, and the gear portions of the drive transmission gear 1781 and the driving-side flange 1763 can mesh appropriately. At this time, the rib-shaped portion 1781p is inserted (into) the gap g between the first gear portion 1763c and the second gear portion 1763d.

[0258] 53(a) and (b), the apparatus main body A includes a motor (not shown), an idler gear 1780, a drive transmission gear 1781, a second drive-side side plate 1783, a main frame 1784, a drive shaft 1782, a reinforcing member 1798, and a compression spring 1785. The second drive-side side plate 1783 corresponds to the second drive-side side plate 83 of the first embodiment. Driving force from the motor is transmitted to the drive transmission gear 1781 via the idler gear 1780. The idler gear 1780, the drive transmission gear 1781, and the reinforcing member 1798 are supported by a fixed drive shaft 1782 so as to be rotatable coaxially about a rotation axis L2 and movable in the direction of the rotation axis L2. One end of the drive shaft 1782 is fixed to a second drive-side side plate 1783, and the other end 1782b is fitted into and supported by a hole 1784a in a main frame 1784. The drive shaft 1782 is provided so that the rotation axis L2 of the drive transmission gear 1781 is parallel to the rotation axis L1 of the drum 62 when the cartridge B is attached to the apparatus main body A.

[0259] A compression spring 1785 is provided between the other end 1780b of the idler gear 1780 and the second drive-side side plate 1783, and the idler gear 1780 is biased toward the main frame 1784 (in the direction H) in relation to the direction of the rotation axis L2. A recess 1780a recessed in the direction of the rotation axis L2 is provided at the end of the idler gear 1780 facing the drive transmission gear 1781, and a protrusion (drive force transmission portion) 1780a1 is provided inside the recess 1780a.

[0260] The drive transmission gear 1781 has a protrusion 1781a1 that protrudes in the direction of the rotation axis L2 at an end thereof facing the idler gear 1780, at a location facing the recess 1780a1 of the idler gear 1780. The protrusion 1781a1 has a surface 1781e at its upstream end in the rotation direction I and a sloped surface 1781h at its downstream end. The surface 1781e is perpendicular to a plane perpendicular to the rotation axis L2, and the sloped surface 1781h is inclined with respect to the plane perpendicular to the rotation axis L2. The protrusion 1780a1 of the idler gear 1780 engages with the surface 1781e of the protrusion 1781a1, transmitting driving force from the idler gear 1780 to the drive transmission gear 1781, and the idler gear 1780 and the drive transmission gear 1781 rotate integrally in the rotation direction I.

[0261] On the other hand, when the drive transmission gear 1781 rotates in the rotational direction I relative to the idler gear 1780, the inclined surface 1781h of the protrusion 1781a1 of the drive transmission gear 1781 abuts against the protrusion 1780a1 of the idler gear 1780. As a result, a force acts on the idler gear 1780 and the drive transmission gear 1781 in a direction moving them away from each other in the direction of the rotational axis L2, and the idler gear 1780 moves in the J direction against the spring force of the compression spring 1785, causing the protrusion 1780a1 to overcome the protrusion 1781a1, and the drive force in the rotational direction I is not transmitted from the drive transmission gear 1781 to the idler gear 1780. During the process of mounting cartridge B into the apparatus main body A, the drive transmission gear 1781 may mesh with the drive side flange 1763 and be rotated in rotation direction I, but at this time, due to the configuration described above, the drive force in rotation direction I is not transmitted from the drive transmission gear 1781 to the idler gear 1780. Therefore, when a user mounts cartridge B, there is no need to rotate the motor that drives the idler gear 1780 or rotate the photosensitive drum 1762, so the load when mounting cartridge B into the apparatus main body A can be reduced.

[0262] Further, drive transmission gear 1781 has hole 1781f, the inner periphery of which is provided with engaging portion 1781g configured with a plurality of concave and convex shapes. Reinforcing member 1798 has engaging portion 1798b configured with a plurality of concave and convex shapes on its outer periphery, and is inserted into hole 1781f. Engaging portion 1781g of drive transmission gear 1781 and engaging portion 1798b of reinforcing member 1798 mesh with each other. Reinforcing member 1798 is in contact with drive shaft 1782 and is directly supported by drive shaft 1782, and drive transmission gear 1781 is indirectly supported by drive shaft 1782 via reinforcing member 1798. However, drive transmission gear 1781 may also be configured to be directly supported by drive shaft 1782.

[0263] However, when manufacturing a relatively large-diameter drive transmission gear 1781 by resin molding as in this embodiment, a configuration in which the drive transmission gear 1781 is supported by the drive shaft 1782 via a reinforcing member 1798 is advantageous in terms of achieving both gear molding precision and strength. This is because, when a gear with a relatively large radial thickness (the radial distance from the inner circumferential surface of the hole through which the shaft passes to the gear root circle) is made of a single resin-molded member, a lightening hole must be provided to prevent deterioration of the gear molding precision due to sink marks in the resin. Furthermore, providing a lightening hole may reduce the strength of the gear. Therefore, by providing a reinforcing member 1798 that is separately molded from resin rather than supporting the drive transmission gear 1781 directly on the drive shaft 1782 as in this embodiment, it is possible to suppress deterioration of the gear molding precision of the resin-molded drive transmission gear 1781 while also suppressing a decrease in strength.

[0264] <Drive transmission operation> Next, the meshing operation between the drive transmission gear 1781 and the drive side flange 1763 will be described using Figures 54 and 55. Figures 54(c), 54(d), 55(a), 55(b), and 55(c) are schematic cross-sectional views of the meshing portion between the gear portion of the drive transmission gear 1781 and the gear portion of the drive side drum flange 1763. Note that these cross-sections are tangent to the meshing pitch circle between the drive transmission gear 1781 and the drive side flange 1763. Figures 54(c), 54(d), 55(a), 55(b), and 55(c) all chronologically show the states after the drive transmission gear 1781 starts to drive, in that order.

[0265] First, when the cartridge B is not attached to the main body A, the drive transmission gear 1781 is biased in the H direction by the compression spring 1785 and abuts against the main frame 1784 as shown in FIG. 54(a).

[0266] <Operation after drive starts> After cartridge B is attached to main assembly A, drive transmission gear 1781 is driven by a motor (not shown) of apparatus main assembly A via an idler gear 1780 (see FIG. 53) and rotates in direction I. Drive side flange 1763 receives a driving force from drive transmission gear 1781 rotating in direction I and rotates in direction K.

[0267] Immediately after the drive transmission gear 1781 starts to rotate in the I direction, as shown in FIG. 54(c), the second main body gear portion 1781d of the drive transmission gear 1781 first meshes with the second gear portion 1763d of the drive-side flange 1763 to transmit the drive force FD. The second main body gear portion 1781d generates a thrust force that presses the second gear portion 1763d in the H direction. However, the drive-side flange 1763 is restricted from moving in the H direction by the rib 1771p (see FIG. 51(a)), and receives a reaction force in the J direction that corresponds to the thrust force in the H direction. Therefore, the second main body gear portion 1781d receives a thrust force F5 in the J direction due to the action of the reaction force from the second gear portion 1763d. This thrust force F5 moves the drive transmission gear 1781 in the J direction.

[0268] As the drive transmission gear 1781 continues to rotate and moves in the J direction, as shown in Figure 54(d), the first gear portion 1763c also meshes with the first main body gear portion 1781c, transmitting the drive force FD and generating a thrust force F6 in the first main body gear portion 1781c. The thrust force F6 is a thrust force in the J direction, the same as the thrust force F5 that the second main body gear portion 1781d previously received when meshed with the second gear portion 1763d. This causes the drive transmission gear 1781 to move further in the J direction.

[0269] As the drive transmission gear 1781 rotates further and moves in direction J, eventually, as shown in Figure 55(a), the second main body gear portion 1781d disengages from the second gear portion 1763d. Meanwhile, the meshing between the first gear portion 1781c and the first gear portion 1763c is maintained, and a thrust force F8 acts on the first gear portion 1781c in direction J. At this time, the drive transmission gear 81 transmits the driving force FD only through the meshing between the first main body gear portion 1781c and the first gear portion 1763c, causing the drive-side flange 1763 to rotate.

[0270] As the rotation continues and the drive transmission gear 1781 moves in the J direction, as shown in Figures 55(b) and (c), the second main body gear portion 1781d eventually comes into contact with the tooth surface (contact portion) 1763d2 of the second gear portion 1763d on the downstream side in the I direction. Note that the surface 1781c1 of the first main body gear portion 1781c and the surface 1763c1 of the first gear portion 1763c remain in contact. In other words, the teeth of the first gear portion 1763c are in contact with the first main body gear portion 1781c located upstream in the I direction, and the teeth of the second gear portion 1763d are in contact with the second main body gear portion 1781d located downstream in the I direction. Furthermore, because the first gear portion 1763c and the second gear portion 1763d are integrally molded from resin, the teeth of the first gear portion 1763c are fixed so as not to move (rotate) in the direction I relative to the teeth of the second gear portion 1763d, and the teeth of the second gear portion 1763d are fixed so as not to move (rotate) in the opposite direction to the direction I relative to the teeth of the first gear portion 1763c. Therefore, in this state, the tooth surface 1781c1 of the first main body gear portion 1781c of the drive transmission gear 1781 presses the tooth surface (contact portion) 1763c1, causing the drive-side flange 1763 to rotate, and the tooth surface 1781d2 of the second main body gear portion 1781d of the drive transmission gear 1781 comes into contact with the tooth surface 1763d2, thereby being sandwiched by the drive-side flange 1763. Then, movement of the drive transmission gear 1781 in the direction of the rotation axis L1 stops. The position of the drive transmission gear 1781 in the direction of the rotation axis L1 at this time is defined as the balanced position.

[0271] 55(b), in the balanced state, forces F9, F10, and F1 are applied to the drive transmission gear 1781 in the direction of the rotation axis L1. Force F9 is a thrust force in the J direction that the first main body gear portion 1781c receives as a result of meshing force with the first gear portion 1763c, force F10 is a thrust force in the H direction that the second main body gear portion 1781d receives as a result of meshing force with the second gear portion 6173d, and force F1 is the biasing force of the compression spring 1785 that the drive side flange 1763 receives via the idler gear 1780. In addition, the drive side flange 1763 receives a force from the drive transmission gear 1781 and abuts against the rib 1771p or the side wall 1771m, thereby being positioned in the direction of the rotation axis L1, and a reaction force F11 in the direction of the rotation axis L1 that balances the thrust force received from the drive transmission gear 1781 is generated. 55(b) shows the case where the drive-side flange 1763 is positioned by contacting the rib 1771p. In the balanced state, ignoring friction in the direction of the rotation axis L1, forces F9, F10, F1, and F11 are balanced, and the drive transmission gear 1781 and the drive-side flange 1763 are each positioned in the direction of the rotation axis L1.

[0272] 55(c), in the balanced state, the drive-side flange 1763 is sandwiched (contacted) between the first main body gear portion 1781c and the second main body gear portion 1781d of the drive transmission gear 1781 in the K direction (rotational direction) and is subjected to the following forces: That is, the tooth surface (contact portion) 1763c1 of the first gear portion 1763c comes into contact with the first main body gear portion 1781c disposed upstream in the K direction (first circumferential direction), thereby receiving a driving force FD having a force component in a direction that rotates the drive-side flange 1763 in the K direction (predetermined direction). At the same time, the tooth surface (contact portion) 1763d2 of the second gear portion 1763d comes into contact with the second main body gear portion 1781d disposed downstream in the K direction (first circumferential direction), thereby receiving a restricting force (braking force) FB having a force component in a direction that suppresses (restricts) the rotation of the drive-side flange 1763 in the K direction. For this reason, it can also be said that the first gear portion 1763c is a driving force receiving portion that receives the driving force FD, and the second gear portion 1763d is a restricting force receiving portion that receives the restricting force FB. Note that Figure 55(b) shows a reaction force FF of the driving force FD received by the first main body gear portion 1781c, and a reaction force FE of the restricting force FB received by the second main body gear portion 1781d.

[0273] Also, immediately after the drive transmission gear 1781 starts to rotate in direction I, when the first main body gear portion 1781c of the drive transmission gear 1781 first meshes with the first gear portion 1763c of the drive-side flange 1763 to transmit the drive force FD, the state is as shown in Figure 54(d) or Figure 55(a). Thereafter, in the same manner as described above, the drive transmission gear 1781 moves in direction J toward the drive side while transmitting the drive force FD to the first gear portion 1763c, and transitions to the balanced state shown in Figures 55(b) and 55(c).

[0274] Thus, in this embodiment as well, when the first gear portion 1763c receives the driving force FD and the second gear portion 1763d receives the restricting force FB, there is no backlash (backlash) in the rotational direction (direction I) between the drive-side flange 1763 and the drive transmission gear 1781, i.e., it is a backlash-less state. In this way, the drive-side flange 1763 is driven to rotate in the K direction while maintaining a backlash-less state. While the gears are engaged and transmitting drive power in a backlash-less state, drive power can be transmitted with high rotational accuracy.

[0275] Furthermore, with respect to the direction of the rotation axis L1, the first gear portion 1763c is positioned closer to the protrusion 1763g, which is the supported portion supported by the flat surfaces 1773e and 1773f, than the second gear portion 1763d. The first gear portion 1763c, which receives the driving force FD, exerts a greater force on the tooth surface of the drive-side flange 1763 than the second gear portion 1763d, which receives the restricting force FB. Therefore, the driving force FD may act to tilt the rotation axis L1 of the drum unit 1769, causing the drum 1762 to tilt relative to the ideal rotation axis L1. However, in this embodiment, by positioning the first gear portion 1763c, which receives the driving force FD, closer to the protrusion 1763g, which is the supported portion, than the second gear portion 1763d, it is possible to suppress the tilt of the rotation axis L1 of the drum unit 1769 caused by receiving the driving force FD.

[0276] <Drive Transmission Structure to Developing Roller 1732> In addition, the configuration for transmitting the driving force to the developing roller 1732 in this embodiment is similar to the configuration for transmitting the driving force to the developing roller 532 via the developing coupling member 89 which engages with the coupling member of the main assembly A of the apparatus and receives the driving force as explained in <Other Modifications> of Embodiment 1 using Figure 44.

[0277] The specific configuration will be described with reference to Figures 56 and 57. Figure 56(a) is a perspective view of a drive train that drives the developing roller 1732 of the developing unit 1720. Figure 56(b) is a partial perspective view of the vicinity of a coupling member 1789 of the developing unit 1720. Figure 56(c) is a perspective view of the cartridge B. Figure 57 is a partial perspective view of the vicinity of a main body side coupling member 1799 of the apparatus main body A.

[0278] The developing unit 1720 has a developing coupling member 1789 having a coupling portion 1789a and a gear portion 1789b, which constitute a developing drive train that drives the developing roller 1732, an idler gear 1790 that meshes with the gear portion 1789b, an idler gear 1791 that meshes with the idler gear 1790, and a developing roller gear 1730 that is fixed to one end of the shaft portion of the developing roller 1732 and meshes with the idler gear 1791.

[0279] In the apparatus main assembly A, a main assembly side coupling member 1799 driven by a motor (not shown) is supported on a first drive-side side plate 1715. The main assembly side coupling member 1799 is provided so as to be movable in the direction of the rotation axis. The main assembly side coupling member 1799 and the developing coupling member 1789 rotate integrally with a coupling portion 1789a engaged with each other, thereby transmitting a driving force from the main assembly side coupling member 1799 to the developing coupling member 1789. The driving force is then transmitted from the developing coupling member 1789 to the developing roller 1732 via idler gears 1790, 1791, and the developing roller gear 1730 in this order.

[0280] In addition, the developing unit 1720 is provided with a toner moving member (agitation member) (not shown) that agitates or transports the toner in the toner storage container, and the driving force received by the developing coupling member 1789 is transmitted to this toner moving member via another gear, thereby driving the toner moving member.

[0281] Note that the member driven by the driving force from the development coupling member 1789 is not limited to the above-described development roller 1732 or a toner moving member (not shown), but may be any member (for example, a charging member, a sealing member, a cleaning member, etc.) other than the drum unit 1769 included in the cartridge B. In this way, the member to which the driving force is transmitted from the development coupling member 1789 (a member connected to the development coupling member 1789 so as to be able to transmit the driving force) is not limited to the development roller 1732.

[0282] In this way, the apparatus main assembly A is provided with two systems of driving force output means, namely, the drive transmission gear 1781 and the main assembly side coupling member 1799, as means for outputting driving force to the cartridge B. This makes it possible to perform control such as driving one of the drive transmission gear 1781 and the main assembly side coupling member 1799 while stopping the other. As a specific example, it becomes possible to control driving the developing roller 1732 while stopping the driving of the drum 1762.

[0283] Furthermore, in cartridge B, the drive-side flange 1763 is not included in the components connected to the development drive train that drives the development roller 1732 or the development coupling member 1789 so as to transmit driving force. Therefore, even if a user rotates the drum 1762 while cartridge B is removed from the apparatus main body A, the components connected to the development roller 1732 or the development coupling member 1789 so as to transmit driving force are prevented from being driven in response to the rotation of the drum 1762. This reduces the possibility of toner leakage, etc., occurring due to the development roller 1732 or the development coupling member 1789 being unnecessarily driven.

[0284] In this manner, in this embodiment, the developing roller 1732 is driven by the driving force input to the developing coupling member 1789, but as in the first embodiment, the developing roller 1732 may also be driven by transmitting the driving force from the driving side flange 1763 to the developing roller gear 1730.

[0285] As described above, this embodiment can achieve the same effects as those of the first embodiment. Furthermore, the elements of the aforementioned embodiments can be applied to the configuration of this embodiment. In particular, the configuration of the first helical teeth (first protrusions) 1763ct of the first gear portion 1763c of the drive-side flange 1763 and the second helical teeth (second protrusions) 1763dt of the second gear portion 1763d may be changed to the helical teeth, spur teeth, protrusions, etc. shown in embodiments 2, 3, 4, 5, 6, 10, 11, 12, 13, 14, and 16.

[0286] [Example 18] This embodiment differs from the seventeenth embodiment in that a ring-shaped elastic member is provided to cover the drive-side flange 1763. Other points are the same as the seventeenth embodiment, and detailed explanations will be omitted. Furthermore, among the elements in this embodiment, elements corresponding to elements in the first embodiment are assigned the same reference numerals as the corresponding elements in the first embodiment. Items for these elements that are not specifically explained are the same as the corresponding elements in the first embodiment.

[0287] Figure 61 is a partial perspective view of the vicinity of the drive side flange 1863 of the drum unit 1869. Figure 62 is a cross-sectional view of the second gear portion 1863d and the second main body gear portion 1881d, the cross-section being perpendicular to the rotation axis L1.

[0288] The driving side flange 1863 has the same shape as the driving side flange 1763 of Example 17. In this example, an elastic ring 1801, which is an elastically deformable ring-shaped elastic member, is provided so as to cover the entire or part of the outer periphery of the second gear portion (second unit side gear portion) 1863d.

[0289] The elastic ring 1801 is a thin film of rubber or sponge, and its thickness is preferably about 0.01 to 1 mm for nitrile rubber or the like if rubber is used, or about 1 to 6 mm for sponge or the like. Furthermore, the inner diameter of the elastic ring before attachment to the drive-side flange 1863 is preferably about 0.5 to 0.9 times the outer diameter of the second gear portion 1863d. In this embodiment, the outer diameter of the second gear portion 1863d is Φ20 mm, and the inner diameter of the elastic ring 1801 is Φ14 mm. When the outer diameter of the second gear portion 1863d is Φ20 mm, the inner diameter of the elastic ring 1801 is preferably selected appropriately from a range of Φ10 to Φ18 mm, which is slightly smaller than Φ20 mm. If the inner diameter of the elastic ring 1801 is larger than Φ18 mm, it may come off the second gear portion 1863d. If the inner diameter is smaller than Φ10 mm, the force tightening the second gear portion 1863d may be too strong, resulting in deformation of the second gear portion 1863d.

[0290] 62, when the cartridge B is attached to the apparatus main assembly A, the elastic ring 1801 is elastically deformed and assumes a shape following the second helical teeth 1863dt of the second gear portion 1863d and the second helical teeth 1781dt of the drive transmission gear 81, and the second gear portion 1863d and the second main body gear portion 1781d mesh with each other via the elastic ring 1801. In addition, the first gear portion (first unit side gear portion) 1863c meshes with the first main body gear portion 1781c.

[0291] When the drive transmission gear 1781 rotates in the direction of arrow I, force is transmitted to the second gear portion 1863d from the second main body gear portion 1781d via the elastic ring 1801. Therefore, the second gear portion 1863d functions similarly to the second gear portion 1763d of Example 17. Therefore, when the drive transmission gear 1781 rotates in the direction of arrow I, there is no backlash (backlash) in the rotational direction (direction I) between the drive side flange 1863 and the drive transmission gear 1781, as in Example 17, i.e., a backlash-less state is achieved.

[0292] In addition, the elastic ring 1801 may have a shape having multiple convex portions on its inner periphery that protrude in a direction toward the rotation axis L1 of the drive side flange 1863 so as to fill the multiple gaps 1863ds of the multiple second helical teeth 1863dt of the second gear portion 1863d when it is not in contact with the drive transmission gear 1781, such as before the cartridge B is attached to the apparatus main body A.

[0293] Furthermore, in this embodiment, the elastic ring 1801 is provided on the outer periphery of the second gear portion 1863d. However, the elastic ring 1801 may be provided on the entire or part of the outer periphery of the first gear portion 1863c, or on the entire or part of the outer periphery of both the second gear portion 1863d and the first gear portion 1863c. In these cases, force is transmitted between the tooth surfaces of the respective gears via the elastic ring 1801. Therefore, the first gear portion 1863c and the second gear portion 1863d function similarly to the first gear portion 1763c and the second gear portion 1763d in the seventeenth embodiment. Therefore, when the drive transmission gear 1781 rotates in the direction of arrow I, there is no backlash (backlash) in the rotational direction (direction I) between the drive-side flange 1863 and the drive transmission gear 1781, i.e., a backlash-less state is achieved.

[0294] Furthermore, the driving side flange 1863 has the same shape as the driving side flange 1763 of the seventeenth embodiment, but the shape of the gear teeth and the size of the gear may be changed as appropriate, taking into consideration the thickness of the elastic ring 1801, etc.

[0295] As described above, this embodiment can provide the same effects as those of the seventeenth embodiment. Furthermore, the elements of the above-described embodiments can be applied to the configuration of this embodiment. In particular, the configuration of the first helical teeth (first protrusions) 1863ct of the first gear portion 1863c of the drive-side flange 1863 and the second helical teeth (second protrusions) 1863dt of the second gear portion 1863d may be changed to the helical teeth, spur teeth, protrusions, etc. shown in embodiments 2, 3, 4, 5, 6, 10, 11, 12, 13, 14, and 16.

[0296] [Example 19] This embodiment differs from Example 17 in that the rotation axis (L19, etc.) of the first gear portion (externally toothed gear portion 1902b, etc.) that receives the driving force FD and the rotation axis (L1) of the second gear portion (1963d) that receives the restricting force FB are parallel, not coaxial. Other points are the same as Example 17, and detailed explanations will be omitted. Furthermore, elements in this embodiment that correspond to elements in Example 1 are given the same reference numerals as the corresponding elements in Example 1. Items in these elements that are not specifically explained are the same as the corresponding elements in Example 1.

[0297] <Drum Unit 1969> Figure 63 is a partial perspective view of the drum unit 1969. As shown in Figure 63, the drive-side flange 1963 of the drum unit 1969 includes an internal gear portion 1963f, a second gear portion 1963d, a protrusion 1963g, a small-diameter portion 1963e, and a flange portion 1963h, all of which are centered on the drum rotation axis L1. The internal gear portion 1963f is a spur gear. The drum unit 1969 also includes a gear 1902, which will be described in detail later (see Figure 65, etc.). The gear 1902 includes an external gear portion 1902b as a first gear portion and an internal gear portion 1902a that meshes with the internal gear portion 1963f.

[0298] The protrusion 1963g is generally cylindrical and protrudes from the internal gear portion 1963f in the direction opposite the drum 1962 (downstream in the direction J) along the drum rotation axis L1. The small diameter portion (cylindrical portion) 1963e is generally cylindrical and protrudes from the internal gear portion 1963f toward the drum 1962 (downstream in the direction H) along the drum rotation axis L1. The second gear portion 1963d, like in Example 17, has helical teeth with a helix angle α2 and is provided on the drum 1962 side of the small diameter portion 1963e (downstream in the direction H). The flange portion 1963h is a thin disk-like member having a diameter equal to or greater than the diameter of the drum 1962 and is provided on the drum 1962 side of the second gear portion 1963d (downstream in the direction H).

[0299] <Support structure of drum unit 1969> Next, the structure for supporting the drum unit 1969 will be described with reference to Figures 64, 65, 66 and 67.

[0300] Figure 64 is a side view (viewed from a direction perpendicular to the rotation axis L1) of the cleaning unit 1960 to which the drum unit 1969 is attached. Figure 65 is an exploded perspective view of the drive side portion of the cleaning unit 1960. Figure 66 is a partial cross-sectional view of the vicinity of the drive side flange 1963 of the cleaning unit 1960, the cross-section including the rotation axis L1. Figure 67 is a partial cross-sectional view of the cleaning unit 1960, the cross-section perpendicular to the rotation axis L1 and passing through the internal gear portion 1963f, as seen in the J direction.

[0301] As shown in Figure 64, a cleaning frame 1960a of the cleaning unit 1960 supports a drum unit 1969. The cleaning frame 1960a of the cleaning unit 1960 is made up of a frame member 1971 and a drum bearing member 1973. The cleaning frame 1971 is provided with a drum sliding portion 1971g.

[0302] The drive-side flange 1963 is rotatably supported by the drum bearing 1973 in the same manner as in Example 17. As described in Example 17, after the drive-side flange 1963 of the drum unit 1969 engages with the drive transmission gear 1781, when the drive transmission gear 1781 rotates in a predetermined direction, the drive-side flange 1963 rotates in conjunction with the drive transmission gear 1781, and, as described above, a thrust force in the H direction is generated in the drum unit 1969. This thrust force causes the non-drive-side flange 1964 to come into contact with the drum sliding portion 1971g, restricting movement of the drum unit 1969 in the H direction.

[0303] As shown in Figure 65, the bearing member 1973 is supported by a frame member 1971. A cylindrical portion 19710b, which serves as a positioning portion for the bearing member 1973, is provided on the frame member 1971 so as to protrude toward the drum unit 1969. A cylindrical portion 19730r, which serves as a positioning portion for the bearing member 1973 and the frame member 1971, is provided on the bearing member 1973 so as to protrude toward the drum unit 1969.

[0304] The inner peripheral surface 19710d of the cylindrical portion 19710b is formed in an arc shape, and the center of the arc is located at a position that coincides with the drum rotation axis L1. The outer peripheral surface 19730b of the cylindrical portion 19730r is also formed in an arc shape, and the center of the arc is located at a position that coincides with the drum rotation axis L1. On the other hand, the outer peripheral surface 19710c of the cylindrical portion 19710b is formed in an arc shape, but the central axis L19 of the arc surface (coaxial with the rotation axis L19 of the gear 1902) is located parallel to and coaxial with the drum rotation axis L1, with no misalignment. In other words, the outer peripheral surface 19710c of the cylindrical portion 19710b is located at a position eccentric to the inner peripheral surface 19710d.

[0305] An outer peripheral surface 19710c of the cylindrical portion 19710b supports the gear 1902 so that it can rotate about the rotation axis L19. The gear 1902 has a substantially cylindrical shape, and is provided with an internal gear portion 1902a on the inner peripheral portion and an external gear portion 1902b as a first gear portion (first unit side gear portion) on the outer peripheral portion, with the rotation axis L19 of the cylinder as the center. The internal gear portion 1902a has spur teeth, and the external gear portion 1902b has helical teeth with a helix angle α1, the number of teeth being the same as that of the second gear portion (second unit side gear portion) 1963d of the drive side flange 1963. Furthermore, a support portion 1902c is provided on one end of the gear 1902, and a cylindrical portion 1902d is provided on the other end. The support portion 1902c has a generally cylindrical shape and is provided along the rotation axis L19 to protrude from the external gear portion 1902b and the internal gear portion 1902a in the direction away from the drum 1962 (downstream in the J direction). The cylindrical portion 1902d has a generally cylindrical shape and is provided along the rotation axis L19 to protrude from the external gear portion 1902b and the internal gear portion 1902a toward the drum 1962 (downstream in the H direction).

[0306] As shown in Fig. 66, the inner peripheral surface (supported portion) of the supporting portion 1902c engages with the outer peripheral surface 19710c of the cylindrical portion 19710b, and the gear 1902 is supported by the frame member 1971 to be rotatable about the rotation axis L19. Furthermore, the outer peripheral surface 19730b of the cylindrical portion 19730r engages with the inner peripheral surface 19710d of the cylindrical portion 19710b, and the bearing member 1973 is supported and positioned by the frame member 1971. The driving side flange 1963 penetrates the inner peripheral portion of the gear 1902 and is installed on the cleaning frame 1960a. As in the seventeenth embodiment, the driving side flange 1963 has a protrusion 1963g rotatably supported by the bearing member 1973 about the rotation axis L1.

[0307] 67, the internal gear portion 1963f of the drive-side flange 1963 has spur teeth and has the same number of teeth as the internal gear portion 1902a of the gear 1902. The gear 1902 and the internal gear portion 1902a are installed so that they fit into the internal gear portion 1963f, and the tooth surfaces of the internal gear portion 1902a and the internal gear portion 1963f engage with each other in the rotational direction. In other words, the internal gear portion 1902a and the internal gear portion 1963f are meshed together so as to be able to transmit a rotational driving force.

[0308] As described above, the outer peripheral surface 19710c of the cylindrical portion 19710b of the frame member 1971 is positioned eccentrically relative to the inner peripheral surface 19710d. Therefore, the gear 1902 supported by the outer peripheral surface 19710c is engaged at an eccentric position with respect to the drive-side flange 1963, which is supported on the inner peripheral surface 19710d via the bearing member 1973. In other words, the gear 1902 and the drive-side flange 1963 are rotatably arranged with their respective rotation axes L19 and L1 parallel but non-coaxial, and are capable of transmitting rotational driving force to each other. Note that in FIG. 67, the positions of the rotation axes L19 and L1 are indicated by the intersections of horizontal dashed lines extending left and right and vertical dashed lines extending up and down, respectively. The offset between the horizontal dashed lines corresponding to the rotation axis L19 and the horizontal dashed lines corresponding to the rotation axis L1 can be seen. The gear 1902 can also be called a non-coaxial rotating member connected to the drive-side flange 1963 so as to be capable of transmitting a driving force.

[0309] <Drive force transmission to drum unit 1969> Next, the transmission of drive force to drum unit 1969 will be described with reference to Figures 68 and 69. Figure 68 is a cross-sectional view showing the engagement between drum unit 1969 and drive transmission gear 1781, the cross-section including rotation axis L1. Figure 69 is a cross-sectional view showing the engagement between drum unit 1969 and drive transmission gear 1781, taken along direction J, perpendicular to rotation axis L1 and passing through internal gear portion 1963f.

[0310] 68, similarly to the seventeenth embodiment, the second main body gear portion 81d of the drive transmission gear 1781 meshes with the second gear portion 1963d of the drive side flange 1963. In addition, the first main body gear portion 1781c of the drive transmission gear 1781 meshes with the external gear portion (first gear portion) 1902b of the gear 1902, and the internal gear portion 1902a of the gear 1902 meshes with the internal gear portion 1963f of the drive side flange 1963.

[0311] 69, as the drive transmission gear 1781 rotates in the direction of arrow I, the gear 1902 receives a driving force through meshing between the external gear portion 1902b and the first main body gear portion 1781c, and rotates in the direction of arrow KW around the rotation axis L19. At this time, the internal gear portion 1902a engages with the internal gear portion 1963f of the drive side flange 1963 in the rotational direction, transmitting the driving force to the drive side flange 1963. As a result, the drive side flange 1963 rotates in the direction of arrow K around the rotation axis L1.

[0312] As the drive transmission gear 1781 rotates in the direction of arrow I, the external gear portion 1902b receives a thrust force in the direction of arrow H (see FIG. 68) due to meshing with the first main body gear portion 1781c. Therefore, as shown in FIG. 68, the gear 1902 moves in the direction of arrow H, and the cylindrical portion 1902d abuts against the end face of the second gear portion 1963d of the drive-side flange 1963, restricting (stopping) the movement of the gear 1902 in the direction of arrow H.

[0313] Meanwhile, the drive transmission gear 1781 receives a thrust force due to meshing with the external gear portion 1902b and moves in the direction of arrow J. Then, similar to the seventeenth embodiment, the second main body gear portion 1781d moves to a balanced position where it engages with the second gear portion 1963d of the drive-side flange 1963, and the movement in the direction of the rotation axis L1 stops.

[0314] In this balanced state, the external gear portion (first gear portion) 1902b receives a driving force FD from the first main body gear portion 1781c. Because the gear 1902 can be considered a rigid body, this driving force FD is transmitted to the driving-side flange 1963 by the meshing (engagement) of the internal gear portion 1902a and the internal gear portion 1963f. In other words, the driving-side flange 1963 receives the driving force FD via the gear 1902. Furthermore, the second gear portion 1963d of the driving-side flange 1963 receives a restraining force (braking force) FB from the second main body gear portion 1781d. The teeth of the second gear portion 1963d are fixed so as not to move (rotate) in the opposite direction to the direction I relative to the teeth of the first gear portion 1902b. Therefore, the drum unit 1969 (drum 1962, drive side flange 1963, and gear 1902) is driven in a backlash-free state. Therefore, the same effects as those of the seventeenth embodiment can be obtained by using the configuration of this embodiment.

[0315] Immediately after the drive transmission gear 1781 starts to rotate, the drive-side flange 1963 may rotate in the K direction due to the meshing of the second gear portion 1963d with the second main body gear portion 1781d, and the gear 1902 may rotate in the KW direction due to the meshing of the internal gear portion 1902a with the internal gear portion 1963f. In this case as well, as the drive transmission gear 1781 moves in the J direction, the first main body gear portion 1781c meshes with the external gear portion 1902b, and finally the drive transmission gear 1781 moves to the balanced state described above.

[0316] As described above, in this embodiment, the rotation axis L19 of the external gear portion 1902b (first gear portion) and the rotation axis L1 of the second gear portion 1963d are parallel to each other and not coaxial with each other. In a balanced state, the gear 1902 has the following parts (i) to (iii): (i) input portion: a portion of the external gear portion 1902b that meshes with at least the drive transmission gear 1781 (at least a part of the first gear portion); (ii) transmission portion: a portion of the internal gear portion 1902a that transmits driving force to the drive-side flange 1963 that meshes with the internal gear portion 1963f; and (iii) output portion: a portion between the (i) input portion and the (ii) output portion. Since parts (i) to (iii) of the gear 1902 are substantially rigid in the K direction, they move integrally along the K direction. Therefore, in the balanced state, portions (i) to (iii) of the gear 1902 and the second gear portion 1963d of the drive-side flange 1963 move integrally in the K direction (the direction of rotation about the rotation axis L1). As a result, a force corresponding to the driving force FD and the restricting force FB act on the drive-side flange 1963, realizing drive in a backlash-free state and achieving the same effect as in drive embodiment 17. This also indicates that it is sufficient that the first gear portion receiving the driving force FD and the second gear portion receiving the rotation axis and the restricting force FB are configured to be able to move integrally in the K direction in the balanced state, and that the first gear portion and the second gear portion do not necessarily have to be configured to be always integrally fixed to the drive-side flange 1963 as in embodiments 1 to 18 described above.

[0317] Furthermore, in this embodiment, an example of a configuration in which the rotation axis of the first gear portion receiving the driving force FD and the rotation axis of the second gear portion receiving the restricting force FB are not coaxial is shown. That is, an example is shown in which the rotation axis of the second gear portion (1963d) receiving the restricting force FB is coaxial with the rotation axis (L1) of the drive-side flange (1963), while the rotation axis of the first gear portion (1902b) receiving the driving force FD is not coaxial with the rotation axis (L1) of the drive-side flange (1963). Specifically, the first gear portion (1902b) is provided on the gear 1902, which serves as a non-coaxial rotating member connected to the drive-side flange 1963 so as to be capable of transmitting a driving force. However, the configuration in which the rotation axis of the first gear portion receiving the driving force FD and the rotation axis of the second gear portion receiving the restricting force FB are not coaxial is not limited to this configuration.

[0318] For example, as another example, the rotation axis of the first gear portion that receives the driving force FD may be coaxial with the rotation axis of the drive-side flange, while the rotation axis of the second gear portion that receives the restraining force FB may not be coaxial with the rotation axis of the drive-side flange. In this configuration, specifically, the first gear portion is provided on the drive-side flange, and the second gear portion is provided on a non-coaxial rotating member connected to the drive-side flange so as to be able to transmit the driving force. As a more specific example of the configuration, in the drive-side flange 1763 of Example 17, the first gear portion 1763c may be left as is, and a gear 1902 having a second gear portion may be disposed at the position of the second gear portion 1763d, as in this example.

[0319] As yet another example, the rotation axis of the first gear portion receiving the driving force FD, the rotation axis of the second gear portion receiving the restraining force FB, and the rotation axis of the drive-side flange may not be coaxial with one another. In this configuration, specifically, a first gear portion is provided on a first non-coaxial rotating member connected to the drive-side flange so as to be able to transmit a driving force, and a second gear portion is provided on a second non-coaxial rotating member connected to the drive-side flange so as to be able to transmit a driving force and rotating non-coaxially with the first non-coaxial rotating member. As a more specific example of the configuration, in the drive-side flange 1763 of Example 17, a gear 1902 including a first gear portion may be disposed at the position of the first gear portion 1763c in the same manner as in this embodiment, and a gear 1902 including a second gear portion may be disposed at the position of the second gear portion 1763d in the same manner as in this embodiment.

[0320] The drive force transmission connection between the drive-side flange 1963 and the non-coaxial rotating member (gear 1902) is not limited to the meshing of spur gears such as the internal gear portion 1902a and the internal gear portion 1963f. For example, a drive force transmission connection using a helical gear or multiple protrusions arranged in the circumferential direction may be used. Furthermore, a non-coaxial drive force transmission coupling such as an Oldham coupling (described in detail in Modification 2 of Example 19) may be used as the drive force transmission connection between the drive-side flange 1963 and the non-coaxial rotating member (gear 1902).

[0321] <Modification 1 of Example 19> In the above-mentioned embodiment 19, a configuration was described in which the internal gear portion 1963f of the drive-side flange 1963 and the internal gear portion 1902a of the gear 1902 have the same number of teeth and rotate integrally, but in this modified example, a configuration will be described in which the drive-side flange 1963 and the gear 1902 have different rotation speeds. Figure 70 is an exploded perspective view of the drive-side portion of the cleaning unit 1960. Figure 71 is a cross-sectional view showing the engagement state of the drum unit 1969 and the drive transmission gear 1781, taken along the J direction and perpendicular to the rotation axis L1 and passing through the internal gear portion 1963f.

[0322] Instead of the gear 1902 in the above-described configuration, a gear 1903 is installed as a non-coaxial rotating member, and instead of the driving-side flange 1963, a driving-side flange 1963 is installed. As in the above-described configuration, the gear 1903 is rotatably supported on the outer circumferential surface 1971c of the cylindrical portion 1971b of the cleaning frame 1971, and the driving-side flange 1963 passes through the gear 1903 and is rotatably supported by the bearing member 1973.

[0323] As shown in Fig. 71, the internal gear portion 1903a of the gear 1903 is configured to be larger than the first gear portion 1963c of the drive-side flange 1963, and is even more eccentric than the configuration described above. In Fig. 71, the positions of the rotation axis L19 and the rotation axis L1 are indicated by the intersections of horizontal dashed dotted lines extending left and right and vertical dashed dotted lines extending up and down.

[0324] In the balanced state, at least the portion of the external gear portion 1903b of the gear 1903 that meshes with the drive transmission gear 1781 (at least a part of the first gear portion) and the second gear portion 1963d move together in the rotational direction about the rotation axis L1, thereby achieving the same effect as in the 19th embodiment described above.

[0325] In this embodiment, the first gear portion 1963c of the drive side flange 1963 and the internal gear portion 1903a of the gear 1903 are configured as spur gears, but they may also be configured as helical gears as long as their eccentricity can be tolerated.

[0326] <Modification 2 of Example 19> An explanation will be given of a configuration using an Oldham coupling as a driving force transmission configuration between a non-coaxial rotating member and a drive-side flange 1963. Figure 72 is a partial perspective view of a drum unit 1969. As shown in Figure 72, the drive flange 1963 is provided with a gear portion 1963d, a protrusion 1963g, a small diameter portion 1963e, and a flange portion 1963h, centered on the drum rotation axis L1.

[0327] The small diameter portion 1963e has a substantially cylindrical shape and protrudes from the gear portion 1963c along the drum rotation axis L1 toward the opposite side from the drum 1962 (downstream side in the J direction). The small diameter portion 1963e is provided with a recess 1963r recessed toward the drum 1962 side (downstream side in the H direction). Side surfaces 1963s of the recess 1963r have a planar shape parallel to the drum rotation axis L1 direction and are disposed at equal intervals across the drum rotation axis L1. Two recesses 1963r are provided at symmetrical positions across the small diameter portion 1963g in a direction perpendicular to the drum rotation axis L1.

[0328] The protrusion 1963g has a cylindrical shape and is provided so as to protrude from the small diameter portion 1963e in the opposite direction to the drum 1962 (downstream in the J direction) along the drum rotation axis L1.

[0329] The flange portion 1963h is a thin disk-shaped member having a diameter equal to or larger than the diameter of the drum 1962, and is provided on the drum 1962 side (downstream side in the direction H) of the gear portion 1963d. The gear portion 1963d has helical teeth with a helix angle of α2, similar to that of the seventeenth embodiment.

[0330] The drum unit 1969 also includes a gear 1904 having a gear portion 1904c as a first gear portion, which will be described in detail later, and a driven coupling 1905.

[0331] Next, the configuration of the cleaning unit will be described with reference to FIG. 73. FIG. 73 is an exploded perspective view of the drive side of the cleaning unit, with (a) viewed from the drive side toward the non-drive side and (b) viewed from the non-drive side toward the drive side. As shown in FIGS. 73(a) and (b), a bearing member 1973 is supported by a frame member 1971. A hole 1971d, which serves as a positioning portion for the bearing member 1973, is formed in the side of the frame member 1971. The hole 1971d is formed in an arc shape and is located at a position where the center of the arc coincides with the drum rotation axis L1. In addition, a cylindrical portion 1971b is installed on the frame member 1971 so as to protrude downstream in the H direction. An inner circumferential surface 1971c of the cylindrical portion 1971b is arcuate, and a center line L19 of the arcuate surface is located parallel to but not coaxial with the drum rotation axis L1. In other words, the hole 1971d is provided at a position eccentric to the inner circumferential surface 1971c.

[0332] A gear 1904 serving as a non-coaxial rotating member is rotatably supported on an inner peripheral surface 1971c of the cylindrical portion 1971b. The gear 1904 has a substantially cylindrical shape and includes a through-hole 1904a, a gear portion 1904c serving as a first gear portion on the outer periphery, and a cylindrical portion 1904d, which are arranged coaxially around the axis of the cylinder. The gear portion 1904c has helical teeth with a helix angle of α1. A protrusion 1904b is provided on the side of the gear 1904 so as to protrude downstream in the H direction.

[0333] When the rotation axis of the gear 1904 is defined as the gear rotation axis L19, the side surfaces 1904e and 1904f of the protrusion 1904b have a planar shape parallel to the gear rotation axis L19 and are disposed at equal intervals on either side of the gear rotation axis L19. Furthermore, the protrusion 1904b has an arc shape that does not protrude beyond the tooth bottom of the gear portion 1904c in the radial direction centered on the rotation axis L1. Two protrusions 1904b are provided at symmetrical positions across the through-hole 1904a in a direction perpendicular to the gear rotation axis 1901. The cylindrical portion 1904d protrudes downstream in the J direction. The cylindrical portion 1904d fits into the inner circumferential surface 1971c of the cylindrical portion 1971b of the frame member 1971, thereby rotatably supporting the gear 1904 on the frame member 1971.

[0334] A driven coupling 1905 is installed downstream of the gear 1904 in the H direction. The driven coupling 1905 is substantially cylindrical and includes a through hole 1905a and a cylindrical portion 1905d that are coaxial with each other and centered on the axis of the cylindrical shape. A convex portion 1905b is installed downstream of the cylindrical portion 1905d in the H direction so as to protrude downstream. Furthermore, a concave portion 1905c is installed downstream of the cylindrical portion 1905d in the J direction so as to be recessed downstream in the H direction. Convex portion 1905b has parallel surfaces equally spaced apart from side portion 1963s of concave portion 1963r around the axis of the cylindrical shape, and concave portion 1905c has parallel surfaces equally spaced apart from side portions 1904e and 1904f of convex portion 1904b around the axis of the cylindrical shape, and convex portion 1905b and concave portion 1905c are arranged in perpendicular directions around the axis of the cylindrical shape.

[0335] The protrusion 1904b of the gear 1904 fits into the recess 1905c of the driven coupling 1905 in the direction of the rotation axis L1 of the cylinder, and the protrusion 1904b can move (slide) in the 190Y direction (see FIG. 73(b)) within the recess 1905c. The 190Y direction is a direction parallel to a plane perpendicular to the rotation axis L1. The protrusion 1904b can transmit a driving force to the recess 1905c to rotate the driven coupling 1905 around the rotation axis L1.

[0336] Furthermore, a protrusion 1963g of the drive flange 1963 passes through a through hole 1905a of the driven coupling 1905 and a through hole 1904a of the gear 1904. Here, the radial sizes of the through holes 1905a and 1904a are set to be sufficiently larger than the outer diameter of the protrusion 1963g.

[0337] Furthermore, the protrusion 1905b of the driven coupling 1905 fits into the recess 1963r of the drive flange 1963 in the direction of the rotation axis L1, and the protrusion 1905b can move (slide) in the 190X direction within the recess 1963r. The 190X direction is a direction parallel to a plane perpendicular to the rotation axis L1 and perpendicular to the 190Y direction when viewed along the rotation axis L1. The protrusion 1905b can transmit a driving force that rotates the drive flange 1963 about the rotation axis L1 to the recess 1963r.

[0338] The tip of the protrusion 1963g is rotatably supported by a drum bearing member 1973, as in the seventeenth embodiment.

[0339] As described above, the inner circumferential surface 1971c of the cylindrical portion 1971b of the frame member 1971 is disposed eccentrically with respect to the hole 1971d. Therefore, the gear 1904 supported by the inner circumferential surface 1971c and the driving-side flange 1963 supported coaxially with the hole 1971d are rotatably supported at eccentric positions.

[0340] Next, engagement with the drive transmission gear 1781 will be described using Figures 74 and 75. Figure 74 shows the drum unit 1969 meshing with the drive transmission gear 1781, as viewed from a direction perpendicular to the rotation axis L1. Figures 75(a) to 75(e) are cross-sectional views showing the engagement between the drum unit 1969 and the drive transmission gear 1781, taken along the H direction, perpendicular to the rotation axis L1 and passing through the protrusion 1904b of the gear 1904. Note that in Figure 75, the position of the rotation axis L19 is indicated by the intersection of a horizontal dashed line extending left and right and a vertical dashed line extending up and down. However, the position of the rotation axis L1 is omitted for simplicity, since it is the center of the circular protrusion 1963g. The black circle shown on the driven coupling 1905 in Figure 75 indicates a specific part of the driven coupling 1905 and is included to make the rotational phase of the driven coupling 1905 easier to understand.

[0341] As shown in FIG. 74, the second main body gear 1781d of the drive transmission gear 1781 engages with the second gear portion 1963d of the driving side flange 1963, and the first main body gear portion 81c engages with the gear 1904 (first gear portion).

[0342] 75(a) to 75(e), as the drive transmission gear 1781 rotates in the I direction, a driving force is transmitted from the drive transmission gear 1781 to the gear portion 1904c (first gear portion), causing the gear 1904 to rotate in the KW direction around the gear rotation axis L19. The driving force of the drive transmission gear 1781 is then transmitted to the drive flange 1963 via the driven coupling 1905 that engages with the gear 1904, causing the drive flange 1963 to rotate in the K direction (see FIG. 72) around the rotation axis L1.

[0343] As the gear 1904 and the drum unit 1969 rotate, the driven coupling 1905 moves in the 190X direction relative to the drive flange 1963 as the convex portion 1905b (see FIG. 74) moves within the concave portion 1963r of the drive-side flange 1963. Furthermore, the gear 1904 moves in the 190Y direction relative to the driven coupling 1905 as the convex portion 1904b moves within the concave portion 1905c. As a result, the gear 1904 (rotation axis L19) and the drive-side flange 1963 (rotation axis L1) can transmit a driving force for rotation between the gear 1904 and the drive-side flange 1963 while maintaining their eccentric positions (non-coaxial and parallel states).

[0344] Then, by the same action as in the 19th embodiment, the drive transmission gear 1781 moves to the balanced position and enters a balanced state. In the balanced state, the drive transmission gear 1781 receives the restricting force FB at the second gear portion 1963d, and receives a force corresponding to the driving force FD received by the gear portion 1904c (first gear portion) of the gear 1904 at the side portion 1963s via the driven coupling 1905. The teeth of the second gear portion 1963d are fixed so as not to move (rotate) in the reverse direction of the direction I relative to the teeth of the first gear portion 1904c. This results in a backlash-less state, and the same effects as in the 17th embodiment can be obtained.

[0345] As described above, according to Example 19, Modification 1 of Example 19, and Modification 2 of Example 19, it is possible to obtain the same effects as Example 17. Furthermore, it is possible to apply the elements of each of the above-described examples to the configuration of this example. In particular, the configuration of the first helical teeth (first protrusions) of the first gear part and the second helical teeth (second protrusions) of the second gear part may be changed to the helical teeth, spur teeth, protrusions, etc. shown in Examples 2, 3, 4, 5, 6, 10, 11, 12, 13, 14, and 16.

[0346] [Example 20] Next, Example 20 will be described below with reference to Figures 76, 77, 78, and 79. This example differs from Example 17 in that the first gear portion (external teeth portion 2002b) that receives the driving force FD rotates coaxially with the rotation axis (L1) of the second gear portion (2063d) that receives the restricting force FB only in a partial region. Alternatively, this example differs from Example 17 in that the movement of the first gear portion (external teeth portion 2002b) is not limited to rotation around a single rotation axis (L1). Other aspects are the same as Example 17, and detailed description will be omitted. Furthermore, elements in this example that correspond to elements in Example 1 are assigned the same reference numerals as the corresponding elements in Example 1. Regarding these elements, unless otherwise specified, they are the same as the corresponding elements in Example 1.

[0347] <Drum Unit 2069> Figure 76 is a partial perspective view of the drum unit 2069. Figure 77 is an exploded perspective view of the drive side of the cleaning unit 2060 and the drum unit 2069. Figure 78 is a cross-sectional view of the cleaning unit 2060 at the position of the gear portion 2063f of the drive side flange 2063.

[0348] 76, the driving-side flange 2063 is centered on the drum rotation axis L1 and includes a gear portion 2063f, a second gear portion (second unit side gear portion) 2063d, a protrusion 2063g, a small diameter portion 2063e, and a flange portion 2063h. The gear portion 2063f has a pulley shape that is compatible with a toothed belt.

[0349] The protrusion 2063g is generally cylindrical and protrudes from the gear portion 2063f in the opposite direction from the drum 2062 (downstream in the direction J) along the drum rotation axis L1. The small diameter portion 2063e is generally cylindrical and has a diameter equal to or greater than the diameter of the gear portion 2063f but less than the diameter of the second gear portion 2063d. The small diameter portion 2063e is located closer to the drum 2062 (downstream in the direction H) than the gear portion 2063f along the drum rotation axis L1. The second gear portion 2063d has helical teeth with a helix angle of α2, as in Example 17, and is located on the drum 2062 side of the small diameter portion 2063e (downstream in the direction H). The flange portion 2063h is thin and disk-shaped with a diameter equal to or greater than the diameter of the drum 2062, and is located on the drum 2062 side of the second gear portion 2063d (downstream in the direction H).

[0350] As shown in FIG. 77, the drum unit 2069 further includes a belt 2002 (see FIG. 77, etc.). The belt 2002 includes an external tooth portion 2002b as a first gear portion (first unit side gear portion) on its outer periphery, and an internal tooth portion 2002a that meshes with the gear portion 2063f on its inner periphery. The belt 2002 is an elastic belt-shaped member. The external tooth portion 2002b is a helical tooth with a torsion angle of α1.

[0351] Next, the configuration of the drive-side cleaning unit 2060 will be described with reference to FIGS. 77 and 78. As shown in FIG. 77, the bearing member 2073 is supported by a frame member 2071. The frame member 2071 has a substantially cylindrical hole 20710a. The bearing member 2073 has a substantially cylindrical hole 20730a at a position opposite the hole 20710a. A pulley 2001 is installed between the holes 20710a and 20730a. The pulley 2001 has a substantially cylindrical shape extending in the direction of an axis parallel to the rotation axis L1. The pulley 2001 has supported portions 2001a and 2001b, which are substantially cylindrical protrusions, on both ends in the direction parallel to the rotation axis L1, and a pulley-shaped tooth portion 2001c on the circumferential surface of the center portion that corresponds to the internal tooth portion 2002a of the belt 2002. Pulley 2001 also has flange portion 2001d between supported portion 2001a and tooth portion 2001c, with a diameter larger than tooth portion 2001c. Supported portions 2001a and 2001b are rotatably supported in holes 20710a and 20730a, respectively, so that pulley 2001 can rotate about a rotation axis parallel to rotation axis L1.

[0352] <Support structure of drum unit 2069> The support structure of the driving-side flange 2062 and the drum 2062 of the drum unit 2069 by the bearing member 2073 and the frame member 2071 is the same as in the nineteenth embodiment, and therefore description thereof will be omitted. Meanwhile, as shown in FIG. 78 , the belt 2002 of the drum unit 2069 is supported by the pulley 2001 and the gear portion 2063f with the internal tooth portion 2002a meshing with the gear portion 2063f of the driving-side flange 2063 and the tooth portion 2001c of the pulley 2001. The belt 2002 is supported by the driving-side flange 2063 and the pulley 2001 with an appropriate tension so that the portion of the belt 2002 that is not in contact with either the driving-side flange 2063 or the pulley 2001 does not bend significantly. The belt 2002 can circulate due to the rotation of the driving-side flange 2063 (gear portion 2063f) and the pulley 2001 (tooth portion 2001c).

[0353] <Drive force transmission to drum unit 2069> Next, the engagement state with drive transmission gear 1781 will be described with reference to Figures 79 and 80. Figure 79 is a cross-sectional view showing the engagement state between drum unit 2069 and drive transmission gear 1781, taken along direction J at a cross section perpendicular to rotation axis L1 and passing through belt 2002, and Figure 80 is a cross-sectional view showing the engagement state between drum unit 2069 and drive transmission gear 1781, the cross section including rotation axis L1.

[0354] 79, as the drive transmission gear 1781 rotates in the direction of arrow I, the external teeth portion 2002b of the belt 2002 engages with the first main body gear portion 1781c, causing the belt 2002 to circulate in the direction of arrow KC, which is the circulating movement direction. As the belt 2002 circulates, the gear portion 2063f of the drive-side flange 2063, which engages with the internal teeth portion 2002a of the belt 2002, rotates in the direction of arrow K. At this time, if the portion of the belt 2002 that engages with the internal teeth portion 2002a is defined as the rotating portion 2002R, the rotating portion 2002R rotates in the direction K about the rotation axis L1. Therefore, the circulating movement direction KC of the rotating portion 2002R of the belt 2002 coincides with the K direction. Therefore, if the portion of external tooth portion 2002b serving as the first gear portion that is included in rotating portion 2002R is referred to as rotating gear portion 2002bR, rotating gear portion 2002bR rotates coaxially and integrally with drive-side flange 2063 and second gear portion 2063d around rotation axis L1. Additionally, as belt 2002 circulates in the KC direction, pulley 2001 rotates in the direction of arrow V20.

[0355] As the drive transmission gear 1781 rotates in the direction of arrow I, the external teeth portion 2002b receives a thrust force in the direction of arrow H due to meshing with the first main body gear portion 1781c, and the belt 2002 tries to move in the direction of arrow H. However, as shown in Figure 80, because the diameter of the small diameter portion 2063e of the drive side flange 2063 is larger than the diameter of the gear portion 2063f, the end surface 2002E of the belt 2002 abuts against the end surface 2063eE of the small diameter portion 2063e, and the movement of the belt 2002 in the direction of arrow H is restricted (stopped).

[0356] Meanwhile, the drive transmission gear 1781 receives a thrust force due to meshing with the external teeth portion 2002b and moves in the direction of arrow J. Then, similar to the seventeenth embodiment, the second main body gear portion 1781d moves to a balanced position where it engages with the second gear portion 2063d of the driving side flange 1963, and movement in the direction of the rotation axis L1 stops. The operation and function of the first gear portion (external teeth portion 2002b) and the second gear portion 2063d from the start of driving of the drive transmission gear 1781 until the drive transmission gear 1781 reaches the balanced position are the same as those in the nineteenth embodiment.

[0357] In this balanced state, the rotating gear portion 2002bR of the external teeth portion (first gear portion) 2002b receives a driving force FD from the first main body gear portion 1781c. Because the rotating portion 2002R of the belt 2002 can be considered a rigid body, this driving force FD is transmitted to the drive-side flange 2063 by the meshing (engagement) of the internal teeth portion 2002a and the gear portion 2063f. In other words, the drive-side flange 2063 receives the driving force FD via the rotating portion 2002R of the belt 2002. Furthermore, the second gear portion 2063d of the drive-side flange 2063 receives a restraining force (braking force) FB from the second main body gear portion 1781d. The teeth of the second gear portion 2063d are fixed so as not to move (rotate) in the direction opposite to the direction I relative to the teeth of the first gear portion 2002b. Therefore, the drum unit 2069 (drum 2062, driving side flange 2063, and belt 2002) is driven in a backlash-free state. Therefore, the same effects as those of the seventeenth embodiment can be obtained even when the configuration of this embodiment is used.

[0358] In this embodiment, the first gear portion that receives the driving force FD in a balanced state is provided on the belt 2002, but the second gear portion that receives the regulating force FB in a balanced state may be provided on a belt that is supported in the same manner as the belt 2002. Also, the first gear portion that receives the driving force FD may be provided on the belt 2002, while the second gear portion that receives the regulating force FB may be provided on another belt.

[0359] Furthermore, while this embodiment has shown a configuration in which the belt 2002 has the internal tooth portion 2002a and the external tooth portion 2002b as the first gear portion, this is not a limitation. For example, the belt may be a belt that deforms to a shape that follows the shapes of the gear of the drive side flange 2063 and the gear of the drive transmission gear 1781, like the elastic ring 1801 shown in embodiment 18. In this case, the gear portion 2063f of the drive side flange 2063 is shaped to correspond to the first main body gear portion 1781c of the drive transmission gear 1781, and the gear portion 2063f is configured to mesh with the first main body gear portion 1781c via the belt. In this case, the gear portion 2063f can also be considered as the first gear portion that receives the driving force FD. If the belt covers the second gear portion 2063d of the drive side flange 2063 and is arranged so as to follow the gear shape of the second gear portion 2063d, the second gear portion 2063d can be considered as the second gear portion that receives the restraining force FD.

[0360] As described above, this embodiment can achieve the same effects as those of the seventeenth embodiment. Furthermore, the elements of each of the previously described embodiments can be applied to the configuration of this embodiment. In particular, the configuration of the first helical teeth (first protrusions) of the first gear portion and the second helical teeth (second protrusions) of the second gear portion may be changed to the helical teeth, spur teeth, protrusions, etc. shown in embodiments 2, 3, 4, 5, 6, 10, 11, 12, 13, 14, and 16.

[0361] [Example 21] Next, Example 21 will be described below with reference to Figures 81 and 82. This example differs from Example 17 in the direction in which the teeth of the gear portions protrude. That is, in Example 17, the protruding direction of the teeth of each gear portion (first gear portion, second gear portion) was a radial direction centered on the rotation axis L1, but in this example, the protruding direction of the teeth is a direction having a directional component parallel to the rotation axis L1. Other points are the same as in Example 17, and detailed description will be omitted. Furthermore, among the elements in this example, elements corresponding to elements in Example 1 are assigned the same reference numerals as the corresponding elements in Example 1. Items in these elements that are not specifically described are the same as the corresponding elements in Example 1.

[0362] <Drive side flange 2163> Figure 81 is a partial perspective view of the drive side portion of drum unit 2169. Figure 82 is a partial perspective view of drum unit 2169, taken along a cross section of drive side flange 2163 that is perpendicular to rotation axis L1 and passes through protrusion 2163d. As shown in Figure 81, drive side flange 2163 is provided with a first gear portion (first unit side gear portion) 2163c, protrusion 2163d as a second gear portion (second unit side gear portion), protrusion (supported portion) 2163g, small diameter portion 2163e, and flange portion 2163h, with rotation axis L1 as the center.

[0363] The first gear portion 2163c has helical teeth with a twist angle of α1 and has substantially the same shape as the first gear portion 1763c of Example 17. The protrusion (supported portion) 2163g has a substantially cylindrical shape centered on the rotation axis L1 and is provided to protrude from the first gear portion 2163c along the rotation axis L1 in the direction opposite to the drum 2162 (downstream in the J direction). The protrusion 2163g has substantially the same shape as the protrusion 1763g of Example 17.

[0364] The small diameter portion 2163e has a substantially cylindrical shape and is provided so as to protrude along the rotation axis L1 toward the drum 2162 (downstream in the H direction) from the first gear portion 2163c. The flange portion 2163h has a thin disk shape with a diameter equal to or larger than the diameter of the drum 2162 and is provided on the drum 2162 side of the small diameter portion 2163e (downstream in the H direction).

[0365] The protrusion portion 2163d serving as the second gear portion is composed of a plurality of protrusions (teeth) 2163dt. The plurality of protrusions 2163dt is provided in the same number as the number of teeth of the first gear portion 2163c and is formed in a shape that can engage with the second main body gear portion 1781d of the drive transmission gear 1781. Furthermore, the plurality of protrusions (teeth) 2163dt protrude from the flange portion 2163h so as to extend in the J direction, which is toward the side opposite to the drum 2162, along the rotation axis L1. As they extend in the J direction, they are spiral protrusions twisted at a twist angle α2 toward the downstream side of the K direction (the rotation direction K of the drive-side flange 2163), which is a circumferential direction centered on the rotation axis L1. In other words, the protrusion direction PD of the protrusions (teeth) 2163dt from the flange portion 2163h has at least an H direction component parallel to the rotation axis L1 and a K direction component, which is a circumferential direction centered on the rotation axis L1. The twist angle of the multiple protrusions 2163dt is twist angle α2. If the protrusions 2163dt are configured as spur teeth rather than helical teeth, the protrusion direction PD has an H-direction component parallel to the rotation axis L1 but does not have a circumferential (K-direction) component.

[0366] Furthermore, the multiple protrusions 2163dt are involute tooth-shaped teeth having involute surface portions on their side surfaces, and have portions with substantially the same shape as the second helical teeth (second protrusions) 1763dt of the second gear portion 1763d of Example 17. Therefore, the protrusions 2163d can mesh with the second main body gear portion 1781d of the drive transmission gear 1781 to receive the driving force and the regulating force FB, and function as a second gear portion equivalent to the second gear portion 1763d of Example 17.

[0367] 82, the multiple protrusions 2163dt are arranged at equal intervals in the rotation direction K centered on the rotation axis L1. The multiple protrusions 2163dt are formed so that their leading ends are the same distance from the rotation axis L1 and their rear ends are a fixed distance from the small diameter portion 2163e in the radial direction centered on the rotation axis L1. Therefore, a space is formed between the rear ends of the multiple protrusions 2163dt and the outer circumferential surface of the small diameter portion 2163e in the radial direction centered on the rotation axis L1.

[0368] Even with such a driving side flange 2163, the teeth (protrusions 2163dt) of the second gear portion 2163d are fixed so as not to move (rotate) in the direction opposite to direction I relative to the teeth of the first gear portion 2163c. Therefore, the driving force FD and the regulating force FB are received from the drive transmission gear 1781, and the second gear portion 2163d is rotationally driven in direction K while maintaining a backlash-free state, and it is possible to obtain the same effect as in Example 17.

[0369] The driving side flange 2163 in this embodiment may be manufactured by molding multiple separate members and adhering them together. The driving side flange 2163 may also be molded using a different material, such as resin or metal. Since the protrusion 2163dt has a relatively thin shape, it may be preferable to use a metal material.

[0370] In this embodiment, the protrusion direction PD of the protrusions 2163dt, which are the teeth of the second gear portion (protrusion portion 2163d), from the flange portion 2163h is a direction having a J-direction component parallel to the rotation axis L1. However, the protrusion direction PD may also be a direction having an H-direction component parallel to the rotation axis L1. In that case, the flange portion 2163h is disposed at least upstream of the second gear portion (protrusion portion 2163d) in the H-direction. Furthermore, the second gear portion may be configured with teeth that protrude in a radial direction about the rotation axis L1, similar to the second gear portion 1763d of Example 17, while the teeth of the first gear portion 2163c may be formed by protrusions that protrude in a protrusion direction that has a component parallel to the rotation axis L1 (H-direction component or J-direction component). Alternatively, the teeth of the first gear portion 2163c and the teeth of the second gear portion (protrusion portion 2163d) may be formed by protrusions that protrude in a protruding direction having a component parallel to the rotation axis L1 (H direction component or J direction component).

[0371] As described above, this embodiment can provide the same effects as those of the seventeenth embodiment. Furthermore, the elements of the above-described embodiments can be applied to the configuration of this embodiment. In particular, the configuration of the first gear portion of the drive-side flange may be changed to helical teeth, spur teeth, protrusions, etc., as shown in embodiments 2, 3, 4, 5, 6, 10, 11, 12, 13, 14, 16, etc.

[0372] [Example 22] Next, Example 22 will be described below with reference to Figures 83 to 87. This example differs from Example 17 in that it has a member capable of filling the gap g between the first gear portion and the second gear portion. Other points are the same as Example 17, and detailed description will be omitted. Furthermore, among the elements in this example, elements corresponding to elements in Example 1 are assigned the reference numerals associated with the corresponding elements in Example 1. Items for these elements that are not specifically described are the same as the corresponding elements in Example 1.

[0373] <Drive side flange 2263> First, the configuration of the drive-side flange 2263 will be described with reference to Figures 83 and 84. Figure 83 is a partial perspective view of the drive side of the drum unit 2269. Figure 84 is a cross-sectional view of the drum unit 2269, the cross-section being perpendicular to the rotation axis L1 and passing through the eccentric ring 2201. The drive-side flange 2263 is centered on the rotation axis L1 and includes a first gear portion (first unit side gear portion) 2263c, a protrusion 2263d, a small diameter portion 2263e, and a cylindrical support portion 2263g, and further includes the eccentric ring 2201 attached to the small diameter portion 2263e.

[0374] The first gear portion 2263c has helical teeth with a helix angle of α1. The cylindrical support portion (protrusion) 2263g is cylindrical and centered on the rotation axis L1, and is provided so as to protrude from the first gear portion 2263c in the direction away from the drum 2262 (downstream in the J direction) along the rotation axis L1. The small diameter portion 2263e is generally cylindrical and is provided so as to protrude from the first gear portion 2263c toward the drum 2262 (downstream in the H direction) along the rotation axis L1. The protrusion portion (second gear portion, second unit side gear portion, second rotating portion) 2263d is composed of multiple protrusions (second protrusions, teeth) 2263dt extending radially around the rotation axis L1, and is provided so as to protrude from the small diameter portion 2263e toward the drum 2262 (downstream in the H direction) along the rotation axis L1. The multiple protrusions 2263dt are formed in a shape that allows them to engage (mesh) with the second main body gear portion 1781d of the drive transmission gear 1781 to transmit a driving force. Specifically, the multiple protrusions 2263dt are protrusions that protrude in a radial direction about the rotation axis L1, and their tips are configured to be positioned approximately at the same position as the tooth tip circle diameter of the first gear portion 2263c. Furthermore, the multiple protrusions 2263dt are the same in number as the number of teeth of the first gear portion 2263c and are arranged at equal intervals in the rotation direction K about the rotation axis L1. In this way, the multiple protrusions 2263dt mesh with the second main body gear portion 1781d to transmit a rotational driving force. In this respect, the multiple protrusions 2263dt can be referred to as a second gear, and the protrusion portion 2263d can be referred to as a second gear portion. Of course, the protrusion portion 2263d may be a gear portion such as the second gear portion 1763d of the seventeenth embodiment.

[0375] As shown in Figure 84, the eccentric ring (intermediate member) 2201 is a cylindrical member composed of an inner diameter portion 2201a and an outer diameter portion 2201b, but the inner diameter portion 2201a and the outer diameter portion 2201b have different centers. The thick-walled portion 2201c is the most protruding portion of the outer diameter portion 2201b, with the inner diameter portion 2201a as the center, and the thin-walled portion 2201d is the closest portion. The diameter of the inner diameter portion 2201a is approximately the same as the small-diameter portion 2263e of the drive-side flange 2263. The radius of the eccentric ring 2201 from the rotation axis L1 is a maximum radius R2201max at the position of the thick-walled portion 2201c and a minimum radius R2201min at the thin-walled portion 2201d.

[0376] An inner diameter portion 2201a of the eccentric ring 2201 is rotatably supported by a small diameter portion 2263e of the drive-side flange 2263. A thick portion 2201c of the eccentric ring 2201 protrudes in the radial direction beyond the first gear portion 2263c and the protrusion 2263d of the drive-side flange 2263. In other words, the radius R2201max is greater than the maximum radius R2263d of the protrusion 2263d and the radius of the addendum circle of the first gear portion 2263c.

[0377] Furthermore, the thin-walled portion 2201d is recessed in the radial direction from the first gear portion 2263c and the protrusion 2263d of the driving-side flange 2263. That is, the radius R2201min is smaller than the maximum radius R2263d of the protrusion 2263d and the radius of the tip circle of the first gear portion 2263c. In other words, the provision of the thin-walled portion 2201d forms a gap g between the first gear portion 2263g and the protrusion 2263d in the direction of the rotation axis L1. Furthermore, the radius ...

Claims

1. A photosensitive unit detachably attached to a main body of an image forming apparatus, the photosensitive unit having a first main body side helical gear portion and a second main body side helical gear portion that rotate on the same shaft, a photoreceptor rotatable around a rotation axis; a first unit side helical gear portion for meshing with the first main body side helical gear portion; a second unit side helical gear portion for meshing with the second main body side helical gear portion; and the twist direction of the teeth of the second unit side helical gear portion is the same as the twist direction of the teeth of the first unit side helical gear portion, a helix angle of the teeth of the second unit side helical gear portion is larger than a helix angle of the teeth of the first unit side helical gear portion, the first unit side helical gear portion and the second unit side helical gear portion are disposed at one end of the photosensitive unit with respect to the direction of the rotation axis of the photosensitive member, A photosensitive element unit characterized in that, when the first unit side helical gear portion meshes with the first main body side helical gear portion and the second unit side helical gear portion meshes with the second main body side helical gear portion, the first unit side helical gear portion and the second unit side helical gear portion rotate, thereby transmitting the rotational driving force received by the first unit side helical gear portion to the photosensitive element, causing the photosensitive element to rotate.

2. 2. The photosensitive unit according to claim 1, wherein the second unit side helical gear portion is disposed between the photosensitive body and the first unit side helical gear portion in relation to the direction of the rotation axis of the photosensitive body.

3. 3. The photosensitive unit according to claim 1, wherein a gap is formed between the first unit side helical gear portion and the second unit side helical gear portion in the direction of the rotation axis of the photosensitive member.

4. The photosensitive unit described in claim 3, characterized in that the main body of the image forming device has a protrusion between the first main body side helical gear portion and the second main body side helical gear portion, and the protrusion is inserted into the gap when the first unit side helical gear portion is engaged with the first main body side helical gear portion and the second unit side helical gear portion is engaged with the second main body side helical gear portion.

5. The photosensitive unit according to claim 3 or 4, characterized in that it has an intermediate member capable of filling the gap between the first unit side helical gear portion and the second unit side helical gear portion in the direction of the rotation axis of the photosensitive member.

6. 6. The photosensitive unit according to claim 5, wherein the intermediate member is movable between a position where the gap is formed and a position where the gap is filled by rotating.

7. The photosensitive unit according to claim 5, wherein the intermediate member is movable between a position where the gap is formed and a position where the gap is filled by moving in a direction perpendicular to the rotation axis of the photosensitive member.

8. 6. The photosensitive unit according to claim 5, wherein the intermediate member is an elastic member that can be elastically deformed to take a state in which the gap is formed and a state in which the gap is filled.

9. With respect to the direction of the rotation axis of the photosensitive member, the tooth width Wc of the first unit side helical gear portion and the width We of the gap are expressed by the following formula: Wc>We≧Wc / 5 9. The photosensitive unit according to claim 3, wherein the following is satisfied:

10. With respect to the direction of the rotation axis of the photosensitive member, the width We of the gap and the tooth width Wd of the second unit side helical gear portion are expressed by the following formula: Wd>We 10. The photosensitive unit according to claim 9, wherein the following is satisfied:

11. The first unit side helical gear portion and the second unit side helical gear portion have a tooth width Wc of the first unit side helical gear portion and a tooth width Wd of the second unit side helical gear portion, which are expressed by the following formulas, respectively, in relation to the direction of the rotation axis of the photosensitive member. Wc>Wd 11. The photosensitive unit according to claim 1, further comprising at least one tooth that satisfies the following condition.

12. 12. The photosensitive unit according to claim 1, wherein a helix angle of the teeth of the first unit side helical gear portion is 15 degrees or more and 40 degrees or less.

13. 12. The photosensitive unit according to claim 1, wherein a helix angle of the teeth of the first unit side helical gear portion is equal to or greater than 20 degrees and equal to or less than 35 degrees.

14. 14. The photosensitive unit according to claim 1, wherein a helix angle of the teeth of the second unit side helical gear portion is equal to or greater than 20 degrees and equal to or less than 40 degrees.

15. 14. The photosensitive unit according to claim 1, wherein the helix angle of the teeth of the second unit side helical gear portion is between 25[deg.] and 35[deg.].

16. at least one tooth among the plurality of teeth of the first unit side helical gear portion is a tooth constituted by a plurality of first protrusions arranged separately with respect to the direction of the rotation axis of the photosensitive body or the rotation direction of the first unit side helical gear portion, The photosensitive unit according to any one of claims 1 to 15, characterized in that the multiple first protrusions are arranged so as to be able to contact one tooth of the first main body side helical gear portion at multiple locations spaced apart in the direction of the rotation axis.

17. at least one tooth among the plurality of teeth of the second unit side helical gear portion is a tooth constituted by a plurality of second protrusions arranged separately with respect to the direction of the rotation axis of the photosensitive body or the rotation direction of the second unit side helical gear portion, A photosensitive unit described in any one of claims 1 to 16, characterized in that the multiple second protrusions are arranged so that they can each contact one tooth of the second main body side helical gear portion at multiple locations spaced apart in the direction of the rotation axis.

18. 18. The photosensitive unit according to claim 1, wherein the number of teeth of the first unit helical gear portion is the same as the number of teeth of the second unit helical gear portion.

19. 18. The photosensitive unit according to claim 1, wherein the first unit side helical gear portion has a missing tooth portion.

20. 18. The photosensitive unit according to claim 1, wherein the second unit side helical gear portion has a missing tooth portion.

21. A photosensitive unit according to any one of claims 1 to 20, characterized in that the protruding direction of the teeth of the first unit side helical gear portion and / or the protruding direction of the teeth of the second unit side helical gear portion is a direction having a component parallel to the rotation axis of the photosensitive member.

22. 22. The photosensitive unit according to claim 1, further comprising an elastic member that covers the first unit side helical gear portion and / or the second unit side helical gear portion.

23. A photosensitive unit described in any one of claims 1 to 22, characterized in that while the first unit side helical gear portion and the second unit side helical gear portion rotate in a predetermined direction due to rotation of the first body side helical gear portion and the second body side helical gear portion, the teeth of the second unit side helical gear portion are fixed so that they cannot rotate relative to the teeth of the first unit side helical gear portion in the direction opposite to the predetermined direction.

24. A photosensitive unit described in any one of claims 1 to 23, characterized in that while the first unit side helical gear portion and the second unit side helical gear portion rotate in a predetermined direction due to rotation of the first body side helical gear portion and the second body side helical gear portion, the teeth of the first unit side helical gear portion can come into contact with the teeth of the first body side helical gear portion located upstream in the predetermined direction, and the teeth of the second unit side helical gear portion can come into contact with the teeth of the second body side helical gear portion located downstream in the predetermined direction.

25. 25. The photosensitive unit according to claim 1, wherein the first unit side helical gear portion and the second unit side helical gear portion are rotatable coaxially.

26. 26. The photosensitive unit according to claim 25, wherein the rotation axis of the first unit side helical gear portion and the rotation axis of the second unit side helical gear portion are coaxial with the rotation axis of the photosensitive member.

27. 27. The photosensitive unit according to claim 25, wherein the first unit side helical gear portion and the second unit side helical gear portion are integrally molded.

28. 28. The photosensitive unit according to claim 27, wherein the first unit side helical gear portion and the second unit side helical gear portion are integrally molded from resin.

29. A photosensitive unit described in any one of claims 25 to 28, characterized in that the tooth tip circle diameter of the second unit side helical gear portion is larger than 0.8 times the tooth root circle diameter or tooth tip circle diameter of the first unit side helical gear portion, and smaller than 1.1 times the tooth tip circle diameter of the first unit side helical gear portion.

30. 25. The photosensitive unit according to claim 1, wherein the rotation axis of the first unit helical gear portion and the rotation axis of the second unit helical gear portion are not coaxial.

31. 31. The photosensitive member unit according to claim 30, wherein the rotation axis of the first unit side helical gear portion or the rotation axis of the second unit side helical gear portion is coaxial with the rotation axis of the photosensitive member.

32. 32. The photosensitive unit according to claim 30, wherein the rotation axis of the first unit helical gear portion and the rotation axis of the second unit helical gear portion are parallel to each other.

33. 25. The photosensitive unit according to claim 1, wherein the first unit side helical gear portion and / or the second unit side helical gear portion is provided on a belt-like member.

34. 24. The photosensitive unit according to claim 1, wherein the first unit side helical gear portion is connected to the second unit side helical gear portion so as to be capable of transmitting a driving force.

35. 35. The photosensitive unit according to claim 34, wherein the first unit helical gear portion is connected to the second unit helical gear portion with backlash in the rotational direction.

36. The photosensitive unit described in claim 34 or 35, characterized in that the first unit side helical gear portion is capable of being connected to the second unit side helical gear portion in a connected state in which it is capable of transmitting driving force, and a disconnected state in which it is unable to transmit driving force to the second unit side helical gear portion.

37. 25. The photosensitive unit according to claim 1, wherein the rotational driving force received by the first unit side helical gear portion is transmitted to the photosensitive member.

38. A photosensitive unit described in any one of claims 1 to 24, characterized in that it has a flange attached to an end of the photosensitive body in the direction of the rotation axis of the photosensitive body, and the first unit side helical gear portion and the second unit side helical gear portion are provided on the flange.

39. A photosensitive unit described in any one of claims 1 to 36, characterized in that it has a driving force receiving portion that meshes with the first main body side helical gear portion or the second main body side helical gear portion and transmits a driving force that rotates the photosensitive member.

40. 37. The photosensitive unit according to claim 1, further comprising a driving force receiving portion that engages with a driving force applying portion provided in the main body of the image forming apparatus and to which a driving force for rotating the photosensitive member is transmitted.

41. The tooth width Wc1 of the first unit side helical gear portion, which has the largest tooth width in the direction of the rotation axis of the photosensitive member, and the tooth width Wd1 of the second unit side helical gear portion, which has the largest tooth width in the direction of the rotation axis of the photosensitive member, are expressed by the following formula: Wd1≦(4 / 5)・Wc1 12. The photosensitive unit according to claim 11, wherein the following is satisfied:

42. The tooth width Wc1 of the first unit side helical gear portion, which has the largest tooth width in the direction of the rotation axis of the photosensitive member, and the tooth width Wd1 of the second unit side helical gear portion, which has the largest tooth width in the direction of the rotation axis of the photosensitive member, are expressed by the following formula: Wd1≦(3 / 4)・Wc1 12. The photosensitive unit according to claim 11, wherein the following is satisfied:

43. The tooth width Wc1 of the first unit side helical gear portion, which has the largest tooth width in the direction of the rotation axis of the photosensitive member, and the tooth width Wd1 of the second unit side helical gear portion, which has the largest tooth width in the direction of the rotation axis of the photosensitive member, are expressed by the following formula: Wd1≧(1 / 10)・Wc1 43. The photosensitive unit according to claim 11, wherein the following is satisfied:

44. A photosensitive unit described in any one of claims 1 to 43, characterized in that the twist direction of the teeth of the second body side helical gear portion is the same as the twist direction of the teeth of the first body side helical gear portion, the twist angle of the teeth of the second body side helical gear portion is larger than the twist angle of the teeth of the first body side helical gear portion, and the first body side helical gear portion and the second body side helical gear portion rotate integrally.

45. 45. The photosensitive unit according to claim 1, which is detachable from the main body of the image forming apparatus by moving in a direction perpendicular to the rotation axis of the first main body side helical gear portion.

46. 46. ​​A cartridge comprising: a photosensitive unit according to claim 1; and a frame that rotatably supports the photosensitive unit.

Images