Drum unit, drive transmission unit, cartridge, and electronic photo image forming device

Abstract

The present invention achieves the arrangement of a coupling member and a drive transmission member. This drum unit has a photoreceptor drum, and a coupling member that is disposed in the vicinity of an end section of the photoreceptor drum and connected to the photoreceptor drum so as to transmit driving power thereto. The coupling member is configured so as to be tiltable with respect to the rotation axis line of the photoreceptor drum and to decrease the tilt angle with respect to the photoreceptor drum accompanying the rotational drive.

Description

Drum unit, drive transmission unit, cartridge and electrophotographic image forming apparatus

[0001] The present invention relates to a drum unit, a drive transmission unit, a cartridge, and an electrophotographic image forming apparatus.

[0002] An electrophotographic image forming apparatus (image forming apparatus) is an apparatus that forms an image on a recording medium using an electrophotographic image forming process, and examples thereof include electrophotographic copying machines, electrophotographic printers (LED printers, laser beam printers, etc.), facsimile machines, and word processors.

[0003] The cartridge is detachably mounted in the main body of the electrophotographic image forming apparatus, the drum unit is a unit having a photosensitive drum, and the drive transmission unit is a unit having a coupling member.

[0004] In an electrophotographic image forming apparatus (hereinafter simply referred to as an "image forming apparatus"), an electrophotographic photosensitive member, generally drum-shaped, serving as an image carrier, i.e., a photosensitive drum (electrophotographic photosensitive drum), is uniformly charged. Next, an electrostatic latent image (electrostatic image) is formed on the photosensitive drum by selectively exposing the charged photosensitive drum to light. The electrostatic latent image formed on the photosensitive drum is then developed into a toner image using toner as a developer. The toner image formed on the photosensitive drum is then transferred to a recording material such as recording paper or a plastic sheet. Furthermore, heat and pressure are applied to the toner image transferred to the recording material to fix the toner image to the recording material, thereby recording an image.

[0005] Such image forming apparatuses generally require toner replenishment and maintenance of various process means. To facilitate this toner replenishment and maintenance, a practical example is a cartridge in which the photosensitive drum, charging means, developing means, cleaning means, etc. are unitized within a frame and detachably mounted on the image forming apparatus body.

[0006] By making some units of an image forming apparatus detachable from the main body of the apparatus, as with this cartridge, users can perform some maintenance of the apparatus themselves, without relying on service personnel in charge of after-sales service. This significantly improves the operability of the apparatus, making it possible to provide an image forming apparatus with excellent usability. For this reason, this type of cartridge system is widely used in image forming apparatuses.

[0007] One example of a cartridge that is a detachable unit is a process cartridge, which integrates a photosensitive drum and a process means that acts on the photosensitive drum (into a cartridge). In a process cartridge, a coupling member is provided at the tip of the photosensitive drum to transmit a driving force from the main body of the apparatus to the photosensitive drum (see JP 2017-223802 A).

[0008] The present invention is a further development of the above-mentioned prior art.

[0009] A typical configuration disclosed in the present application is a drum unit used in a cartridge, which comprises: a photosensitive drum; and a coupling member disposed near an end of the photosensitive drum and connected to the photosensitive drum so as to be capable of transmitting driving force, wherein the coupling member is tiltable with respect to the rotation axis of the photosensitive drum, and is configured to reduce the angle of tilt with respect to the rotation axis of the photosensitive drum as the drum is rotated.

[0010] Another typical configuration disclosed in the present application is a drive transmission unit that can be attached to the main body of an electrophotographic image forming apparatus, the drive transmission unit having a coupling member and a support member that supports the coupling member, the coupling member being tiltable with respect to the rotation axis of the support member and configured to reduce the tilt angle with respect to the rotation axis of the support member as the coupling member is driven. Another typical configuration disclosed in the present application is a cartridge and an electrophotographic image forming apparatus that include the above-mentioned drum unit or drive transmission unit.

[0011] It is possible to develop the prior art.

[0012] FIG. 1 is a diagram illustrating the configuration of the image forming apparatus main body and the process cartridge.

[0013] FIG. 2 is a cross-sectional view of the image forming apparatus main body and the process cartridge.

[0014] FIG. 3 is a cross-sectional view of the process cartridge.

[0015] FIG. 4 is an exploded perspective view of the process cartridge.

[0016] FIG. 5 is an exploded perspective view of the process cartridge.

[0017] FIG. 6 is a cross-sectional view of the image forming apparatus main body and the process cartridge.

[0018] FIG. 7 is an explanatory diagram of the image forming apparatus main body.

[0019] FIG. 8 is an exploded perspective view of the drum unit.

[0020] FIG. 9 is a perspective view of the process cartridge.

[0021] FIG. 10 is a cross-sectional view of the image forming apparatus main body and the process cartridge.

[0022] FIG. 11 is an explanatory diagram of the coupling unit.

[0023] FIG. 12 is a perspective view of the image forming apparatus main body.

[0024] FIG. 13 is an exploded perspective view of the drum flange unit.

[0025] FIG. 14 is a cross-sectional view of the image forming apparatus main body and the process cartridge.

[0026] FIG. 15 is an explanatory diagram of the coupling unit.

[0027] FIG. 16 is a cross-sectional view of the drive transmission portion and the non-drive transmission portion.

[0028] Example 1

[0029] The first embodiment will be described in detail below with reference to the drawings.

[0030] The direction of the rotation axis of the electrophotographic photosensitive drum is defined as the longitudinal direction.

[0031] In addition, in the longitudinal direction, the side where the electrophotographic photosensitive drum receives a driving force from the image forming apparatus main body is referred to as a driving side, and the opposite side is referred to as a non-driving side.

[0032] The overall configuration and image forming process will be described with reference to FIGS. 2 and 3. FIG.

[0033] FIG. 2 is a cross-sectional view of the main assembly A of the electrophotographic image forming apparatus (electrophotographic image forming apparatus main assembly, image forming apparatus main assembly) and a process cartridge (hereinafter referred to as cartridge B) of the first embodiment.

[0034] FIG. 3 is a cross-sectional view of the cartridge B.

[0035] Here, the apparatus main body A refers to the electrophotographic image forming apparatus excluding the cartridge B. <Overall Configuration of Electrophotographic Image Forming Apparatus>

[0036] The electrophotographic image forming apparatus (image forming apparatus) shown in Figure 2 is a laser beam printer utilizing electrophotographic technology in which a cartridge B is detachably mountable in an apparatus main body A. When the cartridge B is mounted in the apparatus main body A, an exposure device 3 (laser scanner unit) is disposed for forming a latent image on an electrophotographic photosensitive drum 62 serving as an image carrier of the cartridge B. Also, a sheet tray 4 containing a recording medium (hereinafter referred to as sheet material PA) on which an image is to be formed is disposed below the cartridge B. The electrophotographic photosensitive drum 62 is a photosensitive member (electrophotographic photosensitive member) used for forming an electrophotographic image.

[0037] Furthermore, in the apparatus main body A, a pickup roller 5a, a pair of feeding rollers 5b, a transfer guide 6, a transfer roller 7, a conveyance guide 8, a fixing device 9, a pair of discharge rollers 10, a discharge tray 11, etc. are arranged in this order along the conveyance direction C of the sheet material PA. The fixing device 9 is composed of a heating roller 9a and a pressure roller 9b. <Image formation process>

[0038] Next, an outline of the image forming process will be described. Based on a print start signal, the electrophotographic photosensitive drum (hereinafter referred to as the photosensitive drum 62 or simply as the drum 62) is rotated in the direction of arrow R at a predetermined peripheral speed (process speed).

[0039] A charging roller (charging member) 66 to which a bias voltage is applied comes into contact with the outer peripheral surface of the drum 62 and charges the outer peripheral surface of the drum 62 uniformly.

[0040] The exposure device 3 outputs a laser beam L corresponding to the image information. The laser beam L passes through a laser opening 61h provided in the cleaning frame 61 of the cartridge B and scans and exposes the outer peripheral surface of the drum 62. As a result, an electrostatic latent image corresponding to the image information is formed on the outer peripheral surface of the drum 62.

[0041] On the other hand, as shown in FIG. 3, in the developing unit 20 as a developing device, the toner T in the toner chamber 28 is stirred and transported by the rotation of a transport member (stirring member) 30 , and is sent out to the toner supply chamber 29 .

[0042] The toner T is carried on the surface of the developing roller 23 by the magnetic force of the magnet roller 24 (fixed magnet). The developing roller 23 is a developer carrier that carries developer (toner T) on its surface in order to develop the latent image formed on the drum 62.

[0043] The toner T is frictionally charged by the developing blade 25, and the thickness of the layer on the peripheral surface of the developing roller 23 as a developer carrier is regulated.

[0044] The toner T is supplied to the drum 62 in accordance with the electrostatic latent image, developing the latent image. This makes the latent image visible as a toner image. The drum 62 is an image carrier that carries the latent image and an image formed with toner (toner image, developer image) on its surface. As shown in FIG. 2 , a sheet material PA stored in the lower part of the apparatus main body A is fed from the sheet tray 4 by a pickup roller 5 a and a pair of feed rollers 5 b in synchronization with the output timing of the laser light L. The sheet material PA is then transported via a transfer guide 6 to a transfer position between the drum 62 and a transfer roller 7. At this transfer position, the toner image is sequentially transferred from the drum 62 to the sheet material PA.

[0045] The sheet material PA onto which the toner image has been transferred is separated from the drum 62 and transported along a transport guide 8 to a fixing device 9. The sheet material PA then passes through a nip between a heating roller 9a and a pressure roller 9b that constitute the fixing device 9. A pressure and heat fixing process is performed at this nip, and the toner image is fixed to the sheet material PA. The sheet material PA, which has undergone the toner image fixing process, is transported to a pair of discharge rollers 10 and discharged onto a discharge tray 11.

[0046] 3, after transfer, the drum 62 has residual toner removed from its outer peripheral surface by a cleaning member 65, and is then used again in the image forming process. The toner removed from the drum 62 is stored in a waste toner chamber 61b of the cleaning unit 60. The cleaning unit 60 is a unit that includes the photosensitive drum 62.

[0047] In the above, the charging roller 66, the developing roller 23, the transfer roller 7, and the cleaning member 65 are process means that act on the drum 62. <Overall Configuration of the Cartridge>

[0048] Next, the overall structure of cartridge B will be described with reference to Figures 3, 4, and 5. Figure 3 is a cross-sectional view of cartridge B, and Figures 4 and 5 are perspective views illustrating the structure of cartridge B. In this embodiment, the screws used to join the various components will not be described.

[0049] The acting member unit including the lever member will be described later, and therefore will not be described here.

[0050] The cartridge B has a cleaning unit.

[0051] 3, the cleaning unit 60 includes a drum 62, a charging roller 66, a cleaning member 65, and a cleaning frame 61 that supports these components. On the drive side of the drum 62, a drive-side drum flange 71 provided on the drive side is rotatably supported by a hole 69a in a drum bearing 69. In a broad sense, the drum bearing 69 and the cleaning frame 61 can be collectively referred to as the cleaning frame.

[0052] On the non-drive side, as shown in FIG. 4, a drum shaft 64 is press-fitted into a hole 61c provided in the cleaning frame 61, and the hole 63a (see FIG. 8(e)) of the non-drive side drum flange 63 is rotatably supported by the drum shaft 64.

[0053] In the cleaning unit 60 , the charging roller 66 and the cleaning member 65 are disposed in contact with the outer peripheral surface of the drum 62 .

[0054] The cleaning member 65 has a rubber blade 65a, which is a blade-shaped elastic member made of rubber as an elastic material, and a support member 65b that supports the rubber blade. The rubber blade 65a abuts against the drum 62 in a counter direction to the rotation direction of the drum 62. In other words, the rubber blade 65a abuts against the drum 62 with its tip facing upstream in the rotation direction of the drum 62.

[0055] As shown in FIG. 3, the waste toner removed from the surface of the drum 62 by the cleaning member 65 is stored in a waste toner chamber 61 b ​​formed by the cleaning frame 61 and the cleaning member 65 .

[0056] As shown in FIG. 3, a catch sheet 34 for preventing waste toner from leaking from the cleaning frame 61 is provided on the edge of the cleaning frame 61 so as to come into contact with the drum 62 .

[0057] The charging roller 66 is rotatably attached to the cleaning unit 60 via charging roller bearings (not shown) at both ends of the cleaning frame 61 in the longitudinal direction.

[0058] The longitudinal direction of the cleaning frame 61 (the longitudinal direction of the cartridge B) is a direction (axial direction) parallel to the rotation axis of the drum 62. Therefore, hereinafter, when simply referring to the longitudinal direction or the axial direction without any particular specification, this refers to the axial direction of the drum 62.

[0059] The charging roller 66 is pressed against the drum 62 by a charging roller bearing 67 being pressed against the drum 62 by a charging roller biasing member 68. The charging roller 66 is rotated by the rotation of the drum 62.

[0060] 3, the developing unit 20 includes a developing roller 23, a developing container 21 that supports the developing roller 23, and a developing blade 25. The developing roller 23 is rotatably attached to the developing container 21 by a driving side bearing member 26 and a non-driving side bearing member 27 provided on both ends thereof.

[0061] A magnet roller 24 is provided within the developing roller 23. A developing blade 25 is disposed in the developing unit 20 to regulate the toner layer on the developing roller 23. As shown in FIG. 4, spacing members 31 are attached to both ends of the developing roller 23, and the spacing members 31 abut against the drum 62, thereby holding the developing roller 23 and the drum 62 with a small gap. As shown in FIG. 3, a blowout prevention sheet 33 is provided on the edge of the bottom member 22 so as to abut against the developing roller 23 to prevent toner from leaking from the developing unit 20. Furthermore, a transport member 30 is provided in the toner chamber 28 formed by the developer container 21 and the bottom member 22. The transport member 30 agitates the toner contained in the toner chamber 28 and transports the toner to the toner supply chamber 29.

[0062] As shown in FIGS. 4 and 5, the cartridge B is configured by combining a cleaning unit 60 and a developing unit 20 together.

[0063] First, the support boss 26a provided on the drive-side bearing member 26 is fitted into the first hanging hole 61i on the drive side of the cleaning frame 61, and the support boss 27a provided on the non-drive-side bearing member 27 is fitted into the second hanging hole 61j on the non-drive side. This allows the developing unit 20 to be rotatably connected to the cleaning unit 60. Thereafter, the drum bearing 69 is assembled into the cleaning unit 60 to complete the cartridge B.

[0064] In this embodiment, the drive-side biasing member 32L and the non-drive-side biasing member 32R are formed of compression springs. The biasing force of these springs biases the developing unit 20 toward the cleaning unit 60, and the developing roller 23 is reliably pressed toward the drum 62. The developing roller 23 is then held at a predetermined distance from the drum 62 by spacing members 31 attached to both ends of the developing roller 23. <Cartridge Mounting Operation>

[0065] In this embodiment, the operation of mounting cartridge B into the apparatus main body A will be described with reference to FIGS. 1(a), 6, and 7. FIG. 1(a) is a cross-sectional view showing the state of the drive transmission member (drive shaft, drive output member) 1 and the drive-side drum flange unit (drive transmission unit) 70 when cartridge B is mounted in the apparatus main body A and is not driven. FIG. 6(a) is a cross-sectional view showing the state of cartridge B being mounted into the apparatus main body A. FIG. 6(b) is a cross-sectional view showing the state of cartridge B after it has been completely mounted into the apparatus main body A. FIG. 7 is an explanatory view showing the state of the drive transmission member 1 before cartridge B is mounted into the apparatus main body A.

[0066] As shown in Figure 6(a), to mount cartridge B into the apparatus main assembly A, first, the door 13 of the apparatus main assembly A is rotated about a rotation center (not shown) to open it. Next, guided portions 69d, 69e of cartridge B are inserted along guide rails 15d, 15e (only the drive side is shown). Then, as shown in Figure 6(b), mounting of cartridge B is completed when positioned portions 69b, 69c provided on drum bearing member 69 abut against or are inserted close to the positioning portions 15b, 15c of the apparatus main assembly.

[0067] Two cartridge pressing members 17 are rotatably attached near both ends of the opening / closing door 13 in the axial direction. Two cartridge pressing springs 19 are attached to both longitudinal ends of the apparatus main body A. The cleaning frame 61 is provided with cartridge pressed portions 61e at both longitudinal ends as portions that receive the urging force of the cartridge pressing springs 19. By completely closing the opening / closing door 13, a predetermined force is applied from the cartridge pressing spring 19 to the cartridge pressed portion 61e. As a result, the positioned portions 69b and 69c remain in contact with the apparatus main body positioning portions 15b and 15c, and the cartridge B is positioned in a position where image formation is possible (FIG. 6B).

[0068] Here, the mounting and positioning configuration and pressing configuration of the cartridge B on the drive side have been described, but the same configuration applies to the non-drive side as well.

[0069] In this embodiment, as shown in FIG. 7 , one end of the drive transmission member 1 is temporarily supported in the hole 15a of the drive-side side plate 15. Before the cartridge B is installed, the drive transmission member tilts due to its own weight within the range of the play (gap) between the hole 15a and the drive transmission member 1. Furthermore, in order to engage with the drive transmission member 1, the first coupling portion 72 tilts in approximately the same direction as the drive transmission member 1 due to the biasing force of the third biasing member 76 (coupling biasing member, third elastic member, third spring) ( FIG. 9 ). At this time, because the rotational axes of the drive transmission member 1 and the first coupling portion 72 are at an angle, the axis of the drive transmission member 1 is misaligned with the axis of the drum 62 (see FIG. 1A ). In this case, for the drum 62 to rotate stably during driving, the drum 62 must rotate with the rotational axis of the drive transmission member 1 aligned with the rotational axis of the drum 62. <Configuration of the Drive-Side Drum Flange Unit and Coupling Engagement Operation>

[0070] Next, we will explain the operation from the state in which the axis of the drive transmission member 1 is inclined relative to the axis of the drum 62 after the cartridge B has been installed, to the state in which a driving force is applied, the drive transmission member 1 engages with the first coupling portion 72, and becomes coaxial with the axis of the drum 62.

[0071] First, the configuration of the drive side drum flange unit (drive transmission unit) 70 will be described with reference to Figures 8, 9, and 10. Figures 8(a), 8(b), and 8(c) are diagrams illustrating a method for assembling the coupling unit 79. Figure 8(d) is a diagram illustrating a method for assembling the drive side drum flange unit 70. Figure 8(e) is a diagram illustrating a method for assembling the drum unit.

[0072] Fig. 9 is a perspective view showing the configuration of the first coupling portion 72 and the third biasing member (third elastic member, third spring) 76. Fig. 10 is a cross-sectional view showing the state of the drive transmission member 1 and the driving-side drum flange unit 70 when the cartridge B is mounted in the apparatus main body A and is not driven.

[0073] The unit consisting of the various members that rotate together with the photosensitive drum 62 is called a drum unit. The drum unit includes the photosensitive drum 62, a drive-side drum flange unit 70, and a non-drive-side drum flange 63. The drive-side drum flange unit 70 is fixed to one end of the photosensitive drum, and the non-drive-side drum flange 63 is fixed to the other end (second end) of the photosensitive drum opposite to the drive-side drum flange unit 70.

[0074] The drive side drum flange unit 70 is composed of a drive side drum flange 71, a first coupling portion 72, a second coupling portion 73, a first biasing member 74 (first elastic member, first spring, axial biasing member), a second biasing member 75 (second elastic member, second spring, radial biasing member), a pin 78, and a lid member 77.

[0075] The first coupling part 72 is provided with a drive transmission receiver (driving force receiver) 72a to which driving force is transmitted from the drive transmission member 1 of the apparatus main body A. The first coupling part 72 transmits driving force to the second coupling part 73 via a pin 78 (second abutment part). The first coupling part 72 and the pin 78 may be integral. The second coupling part 73 is provided with a drive transmission receiver 73a (second abutment part) to which driving force is transmitted from the first coupling part 72, and a drive transmission part 73b (first abutment part) that transmits driving force to the cover member 77. The cover member 77 is provided with a drive transmission receiver 77a (first abutment part) to which driving force is transmitted from the second coupling part 73.

[0076] As shown in FIG. 8( a), the first coupling portion 72 and the second coupling portion 73 have a shaft portion 72k inserted into a hole portion 73k, and the second coupling portion 73 is supported rotatably relative to the first coupling portion 72. As shown in FIG. 8( b), a second biasing member 75 that biases the first coupling portion 72 and the second coupling portion 73 in the rotational direction is disposed between the first coupling portion 72 and the second coupling portion 73. In this embodiment, the second biasing member 75 is made of a torsion coil spring, and both ends of the spring abut against a spring hook portion 72h of the first coupling portion 72 and a spring hook portion 73h of the second coupling portion 73, respectively, to restrict movement in the rotational direction. As shown in FIG. 8( c), a pin 78 is inserted through each of the pin insertion holes 72d, 73d to form a coupling unit (coupling member) 79.

[0077] Next, as shown in Figure 8(d), after the coupling unit 79 is inserted into the drive-side drum flange 71, a first biasing member 74 is inserted to bias the coupling unit 79 toward the drive side. The lid member 77 is then fixed to the drive-side drum flange 71 by welding or other means to form the drive-side drum flange unit 70. As shown in Figure 8(e), the drive-side drum flange unit 70 and the non-drive-side drum flange 63 are inserted into the drum 62 and fixed by press-fitting, crimping, or other means.

[0078] The drum unit (62, 70, 63) configured in this manner is rotatably supported by the frame (drum bearing 69) of the cartridge B. The drum unit (62, 70, 73) can be attached to the main assembly A of the apparatus as a part of the cartridge B.

[0079] The pin 78, first coupling portion 72, and second coupling portion 73 of the drum unit are collectively referred to as the coupling members. These coupling members (72, 73, 78) are connected to a drive transmission member (described below) of the main assembly A of the apparatus to transmit a driving force (rotational force) from the main assembly A to the drum 62. In this embodiment, the coupling member is a unit that can be disassembled into multiple members (78, 72, 73). However, this configuration is not limited to this, and the coupling member may be configured as a single unit. For example, instead of connecting the first coupling portion 72 and the second coupling portion 73 with the pin 78, the first coupling portion 72 and the second coupling portion 73 may be originally configured as a single component. Such a configuration will be described later. The lid member 77 and the drive-side drum flange 71 are also collectively referred to as the flange member, and the lid member 77 may be considered part of the drive-side drum flange 71.

[0080] The flange members (71, 77) are fixed to one end of the drum 62 and connect the drum 62 and the coupling members (72, 73, 78) so as to be capable of transmitting drive power. The flange members are end members attached to the ends of the drum 62. The coupling members (72, 73, 78) are supported by the flange members and are therefore positioned near the ends of the photosensitive drum 62.

[0081] The flange members (71, 77) transmit the driving force from the coupling members (72, 73, 78) to the drum 62. The flange members (71, 77) are cartridge-side transmission members (driving force transmission members) that transmit the driving force.

[0082] The flange members (71, 77) are also connecting members that connect the coupling members (72, 73, 78) to the drum 62. The coupling members (72, 73, 78) are indirectly connected to the drum 62 via the flange members (71, 77). As described above, the coupling members are connected to the drum 62 so as to be capable of transmitting drive power. In other words, the coupling members (72, 73, 78) are operatively connected to the drum 62. In other words, the coupling members (72, 73, 78) are connected such that the drum 62 is also rotated (operated) as the coupling members (72, 73, 78) are rotated.

[0083] As will be described in detail later, the coupling members (72, 73, 78) are tiltably supported by the flange members (71, 77). The flange members (71, 77) also serve as support members for supporting the coupling members.

[0084] In this embodiment, the drive force receiving portion (driving force receiving portion, drive force input portion) 72a of the first coupling portion 72 has a substantially triangular convex cross section (see FIG. 16). Specifically, the substantially triangular cross section is twisted counterclockwise on the axis of the drum 62 from the driving side to the non-driving side.

[0085] As shown in Fig. 9, a chamfered portion 72e that is inclined in the longitudinal direction is provided on the triangular ridge of the drive-side end of the first coupling portion 72. Furthermore, as shown in Fig. 10, the size of the chamfered portion 72e is such that, when the drive transmission member 1 is inclined in the V direction due to its own weight, a portion of the chamfered portion 72e is located radially within the drive transmission portion 1a of the drive transmission member 1. More specifically, as shown in Fig. 10, the minimum distance D1 from the drum central axis of the chamfered portion 72e is smaller than the distance D2 from the drum central axis to the inlet of the drive transmission portion of the drive transmission member 1.

[0086] Furthermore, the drive transmitting portion 73b of the second coupling portion 73 and the drive transmitted portion (driving force receiving portion) 77a of the lid member 77 engage with each other, and the cross section of the drive transmitting portion 73b is substantially triangular.

[0087] Furthermore, as shown in FIG. 10 , the first coupling portion 72 is biased toward the drive side in the longitudinal direction (the direction of arrow G) by the first biasing member 74. This causes the spherical regulated portion 72c of the first coupling portion 72 to abut against the conical regulating portion 71c of the drive-side drum flange 71. This ensures that a portion of the first coupling portion 72 is positioned within the drive transmission portion 1a in the longitudinal direction when the cartridge B is completely installed (see FIG. 1A ). Here, the drive transmission portion 73b and the drive transmission portion 77a correspond to an aligning portion (aligning portion) that aligns the rotation axis of the second coupling portion 73 with the rotation axis of the cover member 77 (drum 62). In other words, when the second coupling portion 73 rotates relative to the cover member 77, the drive transmission portion 73b and the drive transmission portion 77a bias the second coupling portion 73 in a direction that reduces the inclination angle of the second coupling portion 73 relative to the cover member 77.

[0088] Next, the engagement operation of the first coupling portion 72 and the second coupling portion 73 will be described with reference to Figures 1 and 11. Figure 1 is a diagram illustrating the engagement operation of the drive transmission member 1, the first coupling portion 72, and the second coupling portion 73. Figure 11 is a diagram illustrating the relative positional relationship of the first coupling portion 72 with the second coupling portion 73.

[0089] FIG. 1A shows a state in which the drive transmission portion 1a of the drive transmission member 1 and the driven portion 72a of the first coupling portion 72 are out of phase with each other after the cartridge B has been installed in the apparatus main assembly A. When the drive transmission member 1 is rotated from this state, the chamfered portion 72e of the first coupling portion 72 swings the drive transmission member 1 in a direction (arrow W in FIG. 1A) that reduces the inclination angle of the drive transmission member 1, which is inclined in the direction of arrow V ( FIG. 10 ), due to its own weight. At the same time, the drive transmission member 1 is pulled toward the non-drive side (arrow N) due to its twisted shape, and as shown in FIG. 1B, the surface 1f of the drive transmission member 1 abuts against the end surface 72f of the first coupling portion 72. Here, the surface 1f of the drive transmission member 1 and the end surface 72f of the first coupling portion 72 are surfaces perpendicular to the rotation axes of the drive transmission member 1 and the first coupling portion 72, respectively. At this time, the drive transmitted portion 72a of the first coupling part 72 and the drive transmitting portion 1a of the drive transmission member 1 are configured to ensure the amount of longitudinal engagement necessary for stable drive transmission. Furthermore, as the phases of the triangles match, the centers of the triangles also match, and as the faces perpendicular to the rotation axes abut against each other, the rotation axes of the drive transmission member 1 and the first coupling part 72 also match. Then, the engagement between the drive transmission member 1 and the first coupling part 72 is completed.

[0090] In this embodiment, the drive transmission member 1 is inclined in the direction of gravity, but the inclination direction is not limited to the direction of gravity, and engagement is possible even if the inclination direction is in any direction as long as the condition that a part of the chamfered portion 72e is located inside the drive transmission member 1a is satisfied, as explained above. Furthermore, even if the rotation axes of the first coupling part 72 and the drive transmission member 1 are not parallel and coaxial, the first coupling part 72 can engage with the drive transmission member 1 as long as the same condition is satisfied.

[0091] As explained above, the drive transmission member 1 and the first coupling part 72 are engaged, enabling drive transmission from the main assembly A of the apparatus to the cartridge B. At this time, the drive transmission member 1 and the first coupling part 72 are both coaxial, but are still inclined with respect to the drum 62. Next, a configuration will be described in which the drive transmission member 1 and the first coupling part 72, whose rotation axes are inclined with respect to the rotation axis of the drum 62, are aligned with each other.

[0092] A second coupling portion 73 is disposed within the drive-side drum flange 71 and is rotatably supported coaxially with the first coupling portion 72. The pin insertion hole 73d allows for a rotational freedom of 120° or more between the first coupling portion 72 and the second coupling portion 73. Before rotation begins, the first coupling portion 72 is positioned at a first position (see FIG. 11( a) ) where it is biased by a second biasing member 75 in the direction opposite to the rotational direction during driving (the direction of arrow F) relative to the second coupling portion 73. After rotating 120° or more, the first coupling portion 72 moves to a second position (see FIG. 11( b) ) where the pin 78 abuts against the non-drive transmission portion 73a. Here, the pin 78 of the second coupling portion 73 abuts against the non-drive transmission portion 73a. As a result, the second coupling portion 73 receives a driving force from the first coupling portion 72 and does not rotate until the first coupling portion 72 moves from the first position to the second position.

[0093] Subsequently, when the second coupling part 73 reaches the second position (see FIG. 11B ), the pin 78 abuts against the drive transmission receiving part 73 a, transmitting the driving force of the first coupling part 72 and enabling the second coupling part 73 to rotate. Furthermore, as the second coupling part 73 rotates, the drive transmission part 73 b of the second coupling part 73 engages with the drive transmission receiving part 77 a of the cover member 77, enabling the cover member 77 to rotate, as shown in FIG. 1C . At this time, the triangular phases of the drive transmission part 73 b and the drive transmission receiving part 77 a match, and the twisted shape of the second coupling part 73 pulls the second coupling part 73 toward the non-drive side (the direction of arrow N), causing the end face 73 f to abut against the surface 77 f of the cover member 77. Here, the end face 73 f of the second coupling part 73 and the surface 77 f of the cover member 77 are surfaces perpendicular to the rotation axes of the second coupling part 73 and the cover member 77, respectively. The alignment of the triangular phases causes the centers of the triangles to coincide, and the abutment of the faces perpendicular to the rotation axis causes the rotation axes to become parallel. As a result, the rotation axes of the second coupling part 73 and the lid member 77 coincide. Because the lid member 77 is fixed to the drive-side drum flange 71, and the drive-side drum flange 71 is fixed to the drum 62, the rotation axis of the second coupling part 73 coincides with the rotation axis of the drum 62.

[0094] Here, the rotation axes of the drive transmission member 1 and the first coupling part 72 coincide with each other, and the rotation axes of the second coupling part 73 and the drum 62 coincide with each other. Because the first coupling part 72 and the second coupling part 73 are coaxial, the drive transmission member 1 and the drum 62 can rotate with their rotation axes also coinciding with each other.

[0095] As described above, in this embodiment, the first coupling portion 72 can be engaged with the drive transmission member 1 having an axis inclined with respect to the axis of the drum 62, making it coaxial with the drum 62. This configuration can improve the accuracy of drive transmission from the main assembly A of the apparatus to the cartridge B.

[0096] In this embodiment, the coupling member has the first coupling portion 72 and the second coupling portion 73, which are configured to be relatively movable, which provides the following advantages.

[0097] When the drive transmission member 1 starts to rotate, the first coupling portion 72 of the coupling member may not be engaged with the drive transmission member 1. Even in this state, frictional force is generated between the first coupling portion 72 and the drive transmission member 1, which may cause the first coupling portion 72 to rotate slightly before engaging with the drive transmission member 1. If rotation is transmitted from the first coupling portion 72 to the second coupling portion 73 when the first coupling portion 72 is not engaged with the drive transmission member 1, the above-mentioned alignment action unintentionally occurs between the second coupling portion 73 and the flange member (lid member 77). That is, as the second coupling portion 73 engages with the lid member 77 of the flange member, the inclination angle of the second coupling portion 73 relative to the drum 62 decreases. Accordingly, the inclination angle of the first coupling portion 72 relative to the drum 62 also decreases. If the inclination angle of the first coupling part 72 is reduced before the first coupling part 72 engages with the drive transmission member 1, the first coupling part 72 may move away from the drive transmission member 1, and the first coupling part 72 may not be able to engage with the drive transmission member 1.

[0098] Therefore, in this embodiment, the first coupling part 72 is made rotatable relative to the second coupling part 73 within a certain range. Therefore, even if the first coupling part 72 unintentionally rotates slightly before engaging with the drive transmission member 1, the rotation is not transmitted to the second coupling part 73. Only after the drive transmission member 1 and the first coupling part 72 are securely engaged can rotation be transmitted from the first coupling part 72 to the second coupling part 73. Therefore, unintentional alignment does not occur before the first coupling part 72 and the drive transmission member 1 engage with each other.

[0099] In particular, in this embodiment, as described above, the angle (phase difference) by which the first coupling portion 72 can rotate relative to the second coupling portion 73 from the first position to the second position is set to 120 degrees or more.

[0100] The 120 degrees refers to the angle θ = 120° between the lines connecting the center of an equilateral triangle and each vertex (see FIG. 16 ). Even if the phases of the triangles of the drive transmission member 1 and the first coupling part 72 differ when the cartridge is installed in the apparatus main body, the phase difference is 120 degrees or less. In other words, normally, the triangles of the drive transmission member 1 and the first coupling part 72 can engage with each other if the drive transmission member 1 rotates a maximum of 120 degrees. Even if the first coupling part 72 rotates slightly due to the frictional force described above before this engagement, the angle of rotation is less than 120 degrees, and such rotation of the first coupling part 72 does not cause the second coupling part 73 to start rotating.

[0101] As a result, the first coupling portion 72 reliably engages with the drive transmission member 1 and rotates first, and then the second coupling portion 73 starts to rotate, and then the drum 62 becomes rotatable.

[0102] The alignment force generated between the second coupling portion 72 and the flange member (77) can prevent the inclination of the first coupling portion 72 from being corrected before the first coupling portion 72 engages with the drive transmission member 1. As a result, poor engagement between the drive transmission member 1 and the first coupling portion 72 can be prevented.

[0103] However, the coupling member of the coupling unit 79 does not necessarily have to be divided into the first coupling portion 72 and the second coupling portion 73 as described above. For example, if the first coupling portion 72 hardly rotates before engaging with the drive transmission member 1 (for example, if the frictional force generated between the first coupling portion 72 and the drive transmission member 1 is sufficiently small), the above-described configuration is not necessary. In this case, the coupling portion does not have to be divided into the first coupling portion 72 and the second coupling portion 73, and these may be integrated. Furthermore, even if the coupling member is divided into the first coupling portion 72 and the second coupling portion 73, the rotatable angle of the first coupling portion 72 relative to the second coupling portion 73 may be smaller than 120 degrees.

[0104] As described above, in order to enable engagement between the drive transmission portion 1a of the drive transmission member 1 and the drive-received portion 72a of the first coupling portion 72, and between the drive transmission portion 73b of the second coupling portion 73 and the drive-received portion 77a of the cover member 77, each has a characteristic shape. In this embodiment, the triangular shape of the cross section perpendicular to the rotation axis is an equilateral triangle, with each vertex chamfered in an arc shape (see FIG. 16). However, this shape is not necessarily limited to this, as long as the same effect as this embodiment can be obtained. <Cartridge Removal Operation>

[0105] Next, the operation of releasing the engagement between the drive transmission member 1 and the first coupling portion 72 and removing the cartridge B from the main assembly A of the apparatus will be described.

[0106] When the cartridge B is pulled out, the connecting member 2 (FIG. 12) linked to the opening / closing door 13 rotates in the process of opening the opening / closing door 13, and the connecting member 2 moves toward the driving side (in the direction of arrow G) along the inclined portion (not shown) provided on the driving-side side plate 15. Accordingly, the drive transmission member 1 moves toward the driving side. As a result, the drive transmission member 1 moves while rotating in the reverse direction due to its triangular twisted shape, and the engagement with the first coupling part 72 is released. Once the engagement is released, the drive transmission member 1 and the first coupling part 72 are again inclined.

[0107] The configuration of this embodiment described above can be briefly summarized as follows. The drum unit of this embodiment has a coupling member (79) that is engaged and connected to the drive transmission member 1 to receive a driving force (rotational force) (see FIG. 8). The coupling member 79 is tiltably supported by flange members (71, 77) fixed to the photosensitive drum 1. In other words, the angle formed between the rotation axis of the coupling member 79 and the rotation axis of the photosensitive drum 62 varies.

[0108] The drive transmission member 1 is tilted inside the main assembly A of the apparatus (see FIG. 4). To be able to engage with the drive transmission member 1, the coupling member 79 is also tiltable relative to the photosensitive drum 62 (see FIG. 4). In this embodiment, a biasing member (elastic member, spring) 76 is provided in the cartridge B to tilt the coupling member 79 in a predetermined direction so that it can engage with the drive transmission member 1 (see FIG. 9). While the coupling member 79 is tilted, it receives a driving force from the drive transmission member 1 and rotates (see FIG. 1). When the coupling member 79 rotates relative to the flange members (71, 79), a force is applied to the coupling member 79 to reduce its tilt angle due to the action of the centering portions (drive transmission portion 73b, driven transmission portion 77a: see FIG. 8) provided between the coupling member 79 and the flange members (71, 79). This reduces the tilt angle of the coupling member 79 and the drive transmission member 1 connected thereto. As a result, driving force can be stably transmitted from the drive transmission member 1 to the photosensitive drum 62 via the coupling members (72, 73) and flange members (71, 77). In this embodiment, the drive transmission member 1, the coupling members (72, 73), and the photosensitive drum 62 are arranged approximately coaxially when transmitting drive, but they do not necessarily have to be coaxial. In other words, if the inclination angles of the drive transmission member 1 and the coupling members (72, 73) are reduced, the precision of drive transmission is improved.

[0109] As described above, the drive transmission member 1 may tilt or incline inside the main body of the electrophotographic image forming apparatus depending on the support structure for supporting it. In order to transmit drive by engaging and connecting the coupling members (72, 73) to such a drive transmission member 1, the drive transmission structure including the coupling members described in this embodiment is suitable.

[0110] Furthermore, a support structure may be considered in which the drive transmission member 1 is intentionally tilted so that it does not interfere with the installation or removal of the drum unit or cartridge. The drive transmission structure of this embodiment is also useful for such a support structure.

[0111] In this embodiment, the drive-side drum flange unit (drive transmission unit) 70 is integrated with the photosensitive drum to form the drum unit. In other words, the drive transmission unit 70 is detachable from the image forming apparatus main body as part of the drum unit or the cartridge that includes it. However, the drive transmission unit 70 does not necessarily have to be integrated with the photosensitive drum, and the drive transmission unit 70 does not necessarily have to be part of the drum unit or the cartridge.

[0112] That is, the drive transmission unit 70 may be a unit (detachable unit, attachment) or a part thereof that can be attached to the main body of the electrophotographic image forming apparatus by the user. That is, the drive transmission unit 70 may be coupled to the drive transmission member 1 and receive a driving force when attached to the main body of the electrophotographic image forming apparatus. The drive transmission unit 70 may transmit a driving force not to the photosensitive drum 62 but to another member, such as the developing roller 23. The drive transmission unit 70 may not be directly connected to the drive transmission unit (the photosensitive drum in this embodiment). For example, a cartridge may have the drive transmission unit 70 and the photosensitive drum 62, but the two may be located apart and indirectly connected via gears or the like. In this case, too, the coupling member of the drive transmission unit 70 can be operatively connected to the photosensitive drum 62 so as to transmit drive force.

[0113] Alternatively, a configuration in which the drive transmission unit 70 is separable from the drum unit and the cartridge may be considered. In this case, the user first installs the drive transmission unit 70 in the image forming apparatus main body. Then, the user installs the cartridge and the drum unit in the image forming apparatus main body and connects them to the drive transmission unit 70.

[0114] In this embodiment, one of the drive transmission part 73b and the driven transmission part 77a, which are the alignment parts, has a convex shape (protrusion, convex portion), and the other has a concave shape (depression, concave portion) that can engage with the protrusion. When the drive transmission part 73b rotates relative to the driven transmission part 77a, one of the convex and concave shapes rotates relative to the other while engaging. Because at least one of the convex and concave shapes is twisted, when one of the convex and concave shapes rotates relative to the other while engaging, this twisting action causes the axes of the convex and concave shapes to coincide. As a result, the inclination angle of the flange members (71, 77) relative to the coupling member 79 decreases, and the inclination angle of the coupling member 79 relative to the drum 62 also decreases. As a result, the rotation axes of the coupling member 79 and the drum 62 substantially coincide. In this embodiment, the drive transmission part 73b has a convex shape, and the driven transmission part 77a has a concave shape. Furthermore, both the convex and concave shapes are twisted.

[0115] The cross-sectional shapes of the drive transmitting portion 73b and the driven portion 77a are substantially triangular. That is, the cross-sections are shaped like equilateral triangles with arcs near the vertices. However, the cross-sections may have other shapes. Example 2

[0116] Next, a second embodiment will be described. In this embodiment, the drive transmission member 1 is also tiltable (inclinable). In this embodiment, the installation and removal of the cartridge B and the engagement between the drive transmission member 1 and the first coupling portion 82 are similar to those in the first embodiment, and therefore will not be described here. This embodiment is a modified example of the configuration of the drive-side drum flange unit 80, which changes the rotation axis of the first coupling portion 82 and the rotation axis of the drum 62 from a misaligned state to a coaxial state. Therefore, the following description will use Figures 13, 14, and 15 to explain the configuration in which the drive transmission member 1 and the first coupling portion 82 become coaxial with the rotation axis of the drum 62 after they are engaged. Figure 13 is a diagram illustrating a method of assembling the coupling unit 89 and the drive-side drum flange unit 80.

[0117] Figure 14 is a diagram illustrating the engagement operation of the drive transmission member 1, the first coupling portion 82, and the second coupling portion 83. Figure 15 is a diagram illustrating the relative positional relationship of the first coupling portion 82 with respect to the second coupling portion 83.

[0118] 13(a), the coupling unit 89 is made up of a first coupling portion 82, a second coupling portion 83, a second biasing member 85, and a pin 88. As shown in Fig. 13(b), the drive side drum flange unit 80 is made up of a drive side drum flange 81, a coupling unit 89, a first biasing member 84, and a lid member 87.

[0119] The drum unit in this embodiment corresponds to the drum unit in Example 1, in which the driving side drum flange unit 70 (see FIG. 8E) is replaced with a driving side drum flange unit. That is, the drum unit in this embodiment has a driving side drum flange unit 80, a photosensitive drum 62, and a driven side drum flange 63 (see FIG. 8E).

[0120] The drive-side drum flange 81 and the lid member 87 are sometimes collectively referred to as flange members, or the lid member 87 is sometimes considered part of the drive-side drum flange 81. The first coupling portion 82 has a drive-received portion 82a that engages with the drive transmission member 1 to receive the driving force, and a shaft portion 82k, and is tilted by a third biasing member 86 (not shown). The second coupling portion 83 has a hole 83k into which the shaft portion 82k is inserted and rotatably supports the first coupling portion 82 coaxially with the first coupling portion 82, and a drive transmission portion 83b that engages with the drive-received portion 81a of the drive-side drum flange 81 to transmit the driving force. The first biasing member (first elastic member, first spring) 84 biases the first coupling portion 82 and the second coupling portion 83 toward the longitudinal drive side (the direction of arrow G in FIG. 14 ). As in the first embodiment, the second biasing member 85 biases the first coupling portion 82 in the rotational direction relative to the second coupling portion 83.

[0121] The first coupling part 82 and the second coupling part 83 are provided with inclined parts 82g, 83g that abut against each other, allowing longitudinal movement by rotation of the first coupling part 82. When no drive force is transmitted to the first coupling part 82, the first coupling part 82 is biased in the rotational direction by the second biasing member 85, and is located at a first position (see FIG. 15(a) ) where the pin 88 abuts against the end surface of the pin insertion hole 83d of the second coupling part 83. As in the first embodiment, the pin insertion hole 83d of the second coupling part 83 has a rotational degree of freedom of 120° or more. Therefore, when the first coupling part 82 rotates by 120° or more, it reaches a second position (see FIG. 15(b) ) where the pin 88 abuts against the drive transmission part 83a. Then, the driving force of the first coupling part 82 is transmitted, and the second coupling part 83 becomes rotatable. At the same time, in the second position, the second coupling portion 83 moves along the inclined portions 82g, 83g toward the non-drive side (in the direction of arrow N), and the spherical regulated portion 83c (second regulated portion) abuts against the conical regulating portion 87c (second regulating portion) of the lid member 87.

[0122] The second coupling part 83 is provided with a drive transmission part 83b, and the driving side drum flange 81 is provided with a drive transmitted part 81a corresponding to the drive transmission part 83b, and the second coupling part 83 is movable in the longitudinal direction relative to the driving side drum flange 81. When the second coupling part 83 rotates, the driving side drum flange 81 and the drum 62 become rotatable.

[0123] The first coupling portion 82, the second coupling portion 83, and the pin 88 may be collectively referred to as coupling members. The coupling members (82, 83, 88) are configured to transmit a driving force (rotational force) to the photosensitive drum 62 via flange members (81, 87).

[0124] Next, the engagement operation of the first coupling portion 82 and the second coupling portion 83 will be described.

[0125] As shown in FIG. 14A, after the cartridge B is completely installed, the drive transmission member is inclined and does not engage with the first coupling portion 82. At this time, the spherical regulated portion 82c (first regulating portion) of the first coupling portion 82 is in contact with the conical regulating portion 81c (first regulating portion) of the drive-side drum flange 81 by the first biasing member 84. Next, as shown in FIG. 14B, when the drive transmission member 1 rotates, the triangular phases of the drive transmission portion 1a and the drive-received portion 82a coincide, and the face 1f of the drive transmission member 1 abuts against the end face 82f of the first coupling portion 82, causing the drive transmission member 1 to rotate, as in the first embodiment. Therefore, the first coupling portion 82 rotates with the rotation axis of the drive transmission member 1 coincident with the rotation axis of the first coupling portion 82. Then, the inclined portion 83g of the second coupling portion 83 moves along the inclined portion 82g toward the non-drive side in the longitudinal direction (the direction of arrow N). At this time, while the second coupling part 83 is moving along the inclined portion 82g, the hole 83d allows a degree of freedom of rotation of 120° or more between the first coupling part 82 and the second coupling part 83, so the second coupling part 83 does not rotate. When the second coupling part 83 rotates to a predetermined angle of 120° or more, the second coupling part 83 moves along the inclined portion 82g to a second position (see FIG. 15B) on the non-drive side, as shown in FIG. 14C, and the spherical regulated part 83c abuts against the conical regulating part 87c of the lid member 87. At the same time, the second coupling part 83 rotates, and the drive transmission part 83b of the second coupling part 83 abuts against the drive transmission part 81a of the drive-side drum flange 81, causing the drum 62 to rotate.

[0126] Here, the first coupling portion 82 abuts against the restricting portion 81c of the drive-side drum flange 81, and the second coupling portion 83 abuts against the restricting portion 87c of the lid member 87. Therefore, as shown in FIG. 14(c), the positions of the centers Q1 and Q2 of the restricted portion 82c of the first coupling portion 82 and the restricted portion 83c of the second coupling portion 83 are determined. Here, the central axis of the cone shape of the restricting portion 81c of the drive-side drum flange 81 and the central axis of the cone shape of the restricting portion 87c of the lid member 87 are both set to be coaxial with the rotation axis of the drum 62. Furthermore, the centers Q1 and Q2 are set to be located on the rotation axes of the first coupling portion 82 and the second coupling portion 83, respectively. Therefore, because the first coupling portion 82 and the second coupling portion 83 are coaxial, the line connecting the centers Q1 and Q2, i.e., the rotation axes of the first coupling portion 82 and the second coupling portion 83, both coincide with the rotation axis of the drum 62.

[0127] As a result of the above, the drive transmission member 1, the first coupling portion 82, the second coupling portion 83, the lid member 88, the drive side drum flange 81, and the drum 62 can all rotate with their rotation axes aligned.

[0128] As in the first embodiment, the first coupling part 82 in this embodiment can engage with the drive transmission member 1 even if the rotation axis before engagement is inclined with respect to the first coupling part 82. Furthermore, the first coupling part 82 in this embodiment can engage with the drive transmission member 1 even if the rotation axes of the first coupling part 82 and the drive transmission member 1 before engagement are parallel but not coaxial.

[0129] In this embodiment, the restricting portion 81c of the drive-side drum flange 81 and the restricted portion 82c of the first coupling portion 82 are respectively formed in a concave shape with a conical surface and a convex shape with a spherical surface. Similarly, the restricting portion 87c of the lid member 87 and the restricted portion 83c of the second coupling portion 83 are respectively formed in a concave shape with a conical surface and a convex shape with a spherical surface. To obtain the same effect as in this embodiment, the relationship between the concave shape with a conical surface and the convex shape with a spherical surface may be reversed.

[0130] The restricting portions 81c and 87c and the restricted portions 82c and 83c are the alignment portions in the second embodiment.

[0131] As described above, in the second embodiment, as in the first embodiment, the first coupling portion 82 can be engaged with the drive transmission member 1 having an axis inclined with respect to the axis of the drum 62, making it possible to make it coaxial with the drum 62. This configuration can improve the accuracy of drive transmission from the main assembly A of the apparatus to the cartridge B.

[0132] The present embodiment described so far can be summarized as follows.

[0133] In the coupling member of this embodiment, the first coupling portion 82 and the second coupling portion 83 are configured to be relatively movable. As shown in Figure 14(b), the first coupling portion 82 rotates by engaging with the drive transmission member 1. As a result, one of the first coupling portion 82 and the second coupling member 83 moves in the axial direction relative to the other. In other words, the second coupling portion 83 moves in the axial direction of the drum (the direction of arrow N in Figure 14(c)) relative to the first coupling portion 82.

[0134] As a result, the regulated portion 82c of the first coupling portion 82 contacts (is pressed against) the regulating portion 81c of the flange member (drive-side drum flange 81). Furthermore, the regulated portion 83c of the second coupling portion 83 contacts (is pressed against) the regulating portion 87c of the flange member (lid member 77). These contacts align the coupling members (first coupling portion 82, second coupling portion 83). That is, the inclination angle of the coupling members (82, 83) relative to the photosensitive drum 62 decreases. As a result, as shown in FIG. 14(c), the drive transmission member 1, the coupling members (82, 83), and the photosensitive drum 62 are arranged substantially coaxially, improving the precision of drive transmission among them.

[0135] The first coupling part 82 and the second coupling part 83 have inclined parts 82g, 83g (see FIG. 13A) that function as a cam mechanism. Therefore, when the first coupling part 82 rotates relative to the second coupling part 83, the relative positions of the first coupling part 82 and the second coupling part 83 change in the axial direction along the inclined parts 82g, 83g.

[0136] One of the regulated portion 82c provided on the first coupling portion 82 and the regulating portion 81c provided on the flange member (drive-side drum flange 81) has a spherical convex shape, and the other has a spherical or conical concave shape. Also, one of the regulated portion 83c provided on the second coupling portion 83 and the regulating portion 87c provided on the flange member (lid member 77) has a spherical convex shape, and the other has a spherical or conical concave shape.

[0137] The engagement of the concave and convex shapes as described above produces an alignment effect.

[0138] According to the present invention, there are provided a drum unit, a drive transmission unit, a cartridge that can be used in an image forming apparatus such as an electrophotographic image forming apparatus, and an electrophotographic image forming apparatus that is suitable for them.

[0139] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0140] This application claims priority based on Japanese Patent Application No. 2019-109671, filed on June 12, 2019, the entire contents of which are incorporated herein by reference.

Claims

A drum unit for a cartridge that is detachably mountable to a main assembly of an electrophotographic image forming apparatus, said drum unit comprising: a photosensitive drum; anda coupling member provided adjacent to an end portion of the photosensitive drum and connected with the photosensitive drum so as to be capable of transmitting a driving force toward the photosensitive drum by rotating about a rotational axis of the coupling member,wherein the coupling member is inclinable relative to a rotational axis of the photosensitive drum, and the coupling member is configured such that an inclination angle of the coupling member relative to a rotational axis of the photosensitive drum is reduced with rotation of the coupling member about the rotational axis of the coupling member relative to the photosensitive drum. A drum unit according to Claim 1, further comprising a flange member mounted to the end portion of the photosensitive drum, wherein the coupling member is inclinably supported by the flange member. A drum unit according to Claim 2, wherein one of the coupling member and the flange member includes a projection shape portion and the other of the coupling member and the flange member includes a recess shape portion, and wherein when the coupling member is rotated relative to the flange member, the inclination angle of the coupling member is reduced by engagement between the projection shape and the recess shape. A drum unit according to Claim 3, wherein at least one of the projection shape portion and the recess shape portion is twisted. A drum unit according to Claim 3, wherein the projection shape has a triangular cross-section taken along a plane perpendicular to the rotational axis. A drum unit according to Claim 3, wherein the coupling member includes a first coupling portion and a second coupling portion capable of transmitting the driving force from the first coupling portion toward the photosensitive drum, wherein the first coupling portion is rotatable in a predetermined angular range relative to the second coupling portion, and the second coupling portion includes one of the projection shape portion and the recess shape portion.A drum unit according to Claim 2, wherein the coupling member includes a first coupling portion and a second coupling portion capable of transmitting the driving force from the first coupling portion toward the flange member, wherein the flange member includes a first restricting portion and a second restricting portion, and the first coupling portion includes a first restricted portion, and the second coupling portion includes a second restricted portion, and wherein when the first coupling portion carries out rotational driving, (a) one of the first coupling portion and the second coupling portion moves relative to the other in an axial direction of the photosensitive drum, (b) the first restricted portion contacts the first restricting portion, (c) the second restricted portion contacts the second restricting portion, and (d) the coupling member moves such that the inclination angle reduces. A drum unit according to Claim 7, wherein one of the first restricting portion and the first restricted portion includes a projection having a spherical surface, and the other includes a recess having a conical surface or a spherical surface, and one of the second restricting portion and the second restricted portion includes a projection having a spherical surface, and the other includes a conical surface or a spherical surface. A drum unit according to Claim 7 , wherein by rotation of the first coupling portion relative to the second coupling portion, one of the first coupling portion and the second coupling portion moves relative to the other in the axial direction of the photosensitive drum. A drum unit according to Claim 7, wherein at least one of the first coupling portion and the second coupling portion includes an inclined portion, and wherein by rotation of the first coupling portion relative to the second coupling portion, one of the first coupling portion and the second coupling portion moves relative to the other in a direction of the rotational axis along the inclined portion.A drum unit according to Claim 6, further comprising an urging member for urging the first coupling portion to rotate the first coupling portion relative to the second coupling portion. A drum unit according to Claim 6, wherein the first coupling portion is rotatable relative to the second coupling portion by not less than an angle of 120°. A drum unit according to claim 1, further comprising an urging member for urging the coupling member in a direction of the rotational axis of the photosensitive drum. A cartridge comprising: a drum unit according to any one of Claims 1 - 13; and a frame for rotatably supporting said drum unit. A cartridge according to Claim 14, further comprising an urging member for urging the coupling member so as to incline the coupling member relative to the rotational axis of the photosensitive drum. A drive transmission unit detachably mountable to a main assembly of an electrophotographic image formation apparatus, the drive transmission unit comprising: a coupling member configured to transmit the driving force by rotating about a rotational axis of the coupling member; and a support member for supporting the coupling member, wherein the coupling member is inclinable relative to a rotational axis of the support member, and the coupling member is configured such that an inclination angle of the coupling member relative to a rotational axis of the support member is reduced with rotation of the coupling member about the rotational axis of the coupling member relative to the support member. A drive transmission unit according to Claim 16, wherein one of the coupling member and the support member includes a projection shape portion, and the other includes a recess shape portion, and wherein when the coupling member rotates relative to the support member, the inclination angle of the coupling member is reduced by engagement between the projection shaped portion and the recess shape portion. A drive transmission unit according to Claim 17, wherein at least one of the projection shape portion and the recess shape portion has a twisted shape. A drive transmission unit according to Claim 17, wherein the projection shape portion has a triangular cross-section taken along a plane perpendicular to the rotational axis. A drive transmission unit according to Claim 16, wherein the coupling member includes a first coupling portion and a second coupling portion capable of transmitting the driving force from the first coupling portion toward the support member, wherein the first coupling portion is rotatable in a predetermined angular range relative to the second coupling portion, and the second coupling portion includes one of the projection shape portion and the recess shape portion. A drive transmission unit according to Claim 16, wherein the coupling member includes a first coupling portion and a second coupling portion capable of transmitting the driving force from the first coupling portion toward the support member, wherein the support member includes a first restricting portion and a second restricting portion, and the first coupling portion includes a first restricted portion, and the second coupling portion includes a second restricted portion, and wherein when the first coupling portion carries out rotational driving, (a) one of the first coupling portion and the second coupling portion moves relative to the other in an axial direction of the support member, (b) the first restricted portion contacts the first restricting portion, (c) the second restricted portion contacts the second restricting portion, and (d) the coupling member moves such that the inclination angle reduces. A drive transmission unit according to Claim 21, wherein one of the first restricting portion and the first restricted portion includes a projection having a spherical surface, and the other includes a recess having a conical surface or a spherical surface, and one of the second restricting portion and the 5 second restricted portion includes a projection having a spherical surface, and the other includes a conical surface or a spherical surface. A drive transmission unit according to Claim 21, wherein by rotation of the first coupling portion relative to the second coupling portion, 10 one of the first coupling portion and the second coupling portion moves relative to the other in the axial direction of the support member.  A drive transmission unit according to Claim 23, wherein at least one of the first coupling portion and the second coupling portion includes an inclined portion, and wherein by rotation of the first coupling portion relative to the second coupling portion, one of the first coupling portion and the second coupling portion moves relative to the other in a direction of the rotational axis along the inclined portion.  A drive transmission unit according to Claim 20, further comprising an urging member for urging the first coupling portion to rotate the first coupling portion relative to the second coupling portion. A drive transmission unit according to Claim 20, wherein the first coupling portion is rotatable relative to the second coupling portion by not less than an angle of 120°. A drive transmission unit according to Claim 16, further comprising an urging member for urging the coupling member so as to incline the coupling member relative to the rotational axis of the support member. A drive transmission unit according to Claim 16, further comprising an urging member for urging the coupling member in a direction of the rotational axis of the support member. A cartridge comprising: a drive transmission unit according to any one of Claims 16 - 28; and a photosensitive drum capable of receiving a driving force from the drive transmission unit. An electrophotographic image formation apparatus comprising a cartridge according to Claim 14; and a main assembly to which the cartridge is detachably mountable and which includes an inclinable drive output member connectable with the coupling member of the cartridge. An electrophotographic image formation apparatus comprising: a drive transmission unit according to any one of Claims 16 - 28; and a main assembly to which the drive transmission unit is detachably mountable and which includes an inclinable drive output member connectable with the coupling member of the drive transmission unit.

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