Image forming apparatus

Abstract

To prevent vibration of an image holding body even when a gap is generated between a bearing that rotatably supports a rotation shaft of the image holding body and a member that holds the bearing.SOLUTION: An image forming apparatus comprises: a cylindrical image holding body; a rotation shaft that rotates the image holding body; bearings that are provided on both ends of the rotation shaft, and in which an inner ring is rotatable relative to an outer ring, and the inner ring and the rotation shaft inserted into the inner ring rotate integrally; holding members that are attached to a body side and hold the outer rings of the bearings; and pressing parts that press the outer rings of the bearings in one direction to press the outer rings against the holding members.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses that in a process cartridge equipped with a developing cartridge and a photosensitive drum, bearing members are provided on the outer peripheral surface of the non-image forming area at both axial ends of the photosensitive drum, and the photosensitive drum is rotatably supported at three points on the outer peripheral surface by an L-shaped member and a stopper member via the bearing members. As a result, the photosensitive drum is supported on the outer peripheral surface with extremely high precision, and eccentric rotation of the photosensitive drum is easily and reliably prevented, thereby achieving good image formation. Patent document 2 discloses that an image forming device has a photosensitive drum unit, which has a rotatable photosensitive drum, removably attached to the device main body and a positioning part which positions the photosensitive drum unit in the device main body, and includes a drum shaft which is arranged longitudinally along the central axis of the photosensitive drum and has both ends supported by a frame of the photosensitive drum unit, and a bearing which is arranged on the main frame of the device main body so that one end of the drum shaft protruding from the side of the photosensitive drum unit can fit into the bearing, and the drum shaft is inserted into the bearing when the photosensitive drum unit is positioned by the positioning part. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-287570 A [Patent Document 2] JP 2005-275266 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a configuration in which the image carrier that holds an image can be replaced individually, the image carrier and a bearing that supports the rotation shaft of the image carrier are integrally configured, and the image carrier is attached to the main body via a member that holds the bearing. However, if there is a gap between the bearing and the member that holds the bearing to enable replacement, this gap will cause the rotation shaft to fluctuate during rotation of the image carrier, causing the image carrier to vibrate and resulting in image defects. The present invention has an object to suppress vibration of an image carrier even when a gap is generated between a bearing that rotatably supports a rotation shaft of the image carrier and a member that holds the bearing. [Means for solving the problem]

[0005] The invention described in claim 1 is an image forming apparatus comprising: a cylindrical image carrier; a rotating shaft for rotating the image carrier; bearings provided on both ends of the rotating shaft, an inner ring of which can rotate relative to an outer ring, the rotating shaft inserted into the inner ring and the inner ring rotating as one unit with each other; a holding member attached to the main body for holding the outer ring of the bearing; and a pressing section for pressing the outer ring of the bearing against the holding member by pressing the outer ring of the bearing in one direction. The invention described in claim 2 is the image forming apparatus described in claim 1, characterized in that the outer ring of the bearing is pressed in the one direction after the holding member is attached to the main body side. The invention described in claim 3 is the image forming device described in claim 2, characterized in that it is provided with a developer holder that is arranged along the axial direction of the image holder attached to the main body and develops the image holder, and the one direction in which the pressing portion presses the outer ring is a direction connecting the axis of the developer holder and the axis of the image holder. The invention described in claim 4 is the image forming apparatus described in claim 3, characterized in that the pressing portion presses using an elastic member. An invention recited in claim 5 is the image forming apparatus recited in claim 1, wherein the holding member includes a surrounding portion that surrounds a periphery of the outer ring of the bearing and is removable from the outer ring. The invention described in claim 6 is the image forming apparatus described in claim 5, characterized in that the surrounding portion has an opening that exposes a portion of the outer ring, and the pressing portion presses the outer ring through the opening. The invention described in claim 7 is the image forming apparatus described in claim 1, characterized in that the pressing portion is provided on the main body side. The invention described in claim 8 is the image forming apparatus described in claim 7, characterized in that the holding member is provided on both ends of the rotating shaft, and the pressing portion presses the outer ring in the same direction at both ends of the rotating shaft. Effect of the Invention

[0006] According to the invention of claim 1, even if a gap is generated between a bearing that rotatably supports the rotation shaft of the image carrier and a member that holds the bearing, vibration of the image carrier is suppressed. According to the invention of claim 2, the alignment between the device on the main body side and the image carrier can be determined with greater accuracy than in a configuration in which the bearing is pressed before the image carrier is attached to the main body side. According to the invention of claim 3, the positional accuracy of the image carrier relative to the developer carrier is improved and printing defects are suppressed, compared to when the direction in which the pressing portion presses the outer ring is determined regardless of the position of the developer carrier. According to the invention of claim 4, the position of the axis of the image carrier is prevented from varying before and after replacement of the image carrier, as compared to a case in which the pressing force of the pressing portion is determined by the user. According to the invention of claim 5, resources used when replacing the image carrier are reduced compared to when the holding member is not detachable from the image carrier. According to the invention of claim 6, the load on the bearing is suppressed compared to the case where the bearing is pressed in a direction inclined with respect to the rotation axis. According to the seventh aspect of the present invention, the position of the axis of the image carrier and the positional relationship with the device on the main body side can be determined with higher accuracy than when a pressing portion is provided on the holding member. According to the invention of claim 8, tilt of the image carrier is suppressed compared to a case in which the outer ring is pressed in different directions at both ends of the rotation shaft. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an image forming apparatus to which the present embodiment is applied. [Diagram 2] FIG. 2 is a diagram illustrating a state in which a photosensitive drum is attached to an image forming unit. [Diagram 3] 1 is a perspective view showing one end side of a photosensitive drum to which the present embodiment is applied; [Figure 4] FIG. 4 is a diagram for explaining a holder, and is a perspective view showing a state in which the holder is attached to the photosensitive drum in FIG. 3. [Diagram 5] FIG. 3 is a cross-sectional view taken along the line V-V of FIG. 2, illustrating a state in which the holder on which the photosensitive drum is mounted is attached to the frame. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. [Explanation of Image Forming Apparatus 1] FIG. 1 is a diagram illustrating an image forming apparatus 1 to which the present embodiment is applied. The image forming apparatus 1 according to this embodiment includes a paper feed unit 1A, a printing unit 1B, and a paper discharge unit 1C. The paper feed unit 1A includes a first paper storage section 11 to a fourth paper storage section 14 for storing paper P as an example of a recording medium. The paper feed unit 1A also has feed rolls 15-18 that correspond to the first paper storage section 11 to the fourth paper storage section 14, respectively, and feed the paper P stored in each paper storage section to a transport path connected to the printing unit 1B.

[0009] The printing unit 1B includes an image forming section 20 that forms an image on a sheet P. The printing unit 1B also includes a control section 21 that controls each section of the image forming apparatus 1. The printing unit 1B also includes an image processing section 22. The image processing section 22 performs image processing on image data transmitted from the image reading device 4 and the personal computer (PC) 5. The printing unit 1B is also provided with a UI (User Interface) 23, which is configured with a touch panel or the like and notifies the user of information and receives information input from the user.

[0010] The image forming section 20 is provided with six image forming units 30T, 30P, 30Y, 30M, 30C, and 30K (hereinafter, sometimes simply referred to as "image forming units 30") that are arranged in parallel at regular intervals. Each image forming unit 30 includes a photoconductor drum 50 on which an electrostatic latent image is formed while rotating in the direction of arrow A, a charging roll 32 that charges the surface of the photoconductor drum 50, a developing device 34 having a developing roll 33 that develops the electrostatic latent image formed on the photoconductor drum 50, and a drum cleaner 35 that removes toner and the like from the surface of the photoconductor drum 50. The photoconductor drum 50 is disposed so that the center of the rotation axis of the photoconductor drum 50 and the center of the rotation axis of the developing roll 33, which is an example of a developer holder, are at the same height.

[0011] The image forming section 20 is also provided with an exposure device 26 that exposes the photoconductor drum 50 of each image forming unit 30 to laser light. The exposure of the photoconductor drum 50 by the exposure device 26 is not limited to using laser light. For example, a light source such as an LED (Light Emitting Diode) may be provided for each image forming unit 30, and the photoconductor drum 50 may be exposed using light emitted from the light source.

[0012] Each image forming unit 30 is configured similarly, except for the toner contained in the developer 34. The image forming units 30Y, 30M, 30C, and 30K form yellow (Y), magenta (M), cyan (C), and black (K) toner images, respectively. Further, the image forming units 30T and 30P form toner images using toner corresponding to a corporate color, foaming toner for Braille, fluorescent color toner, toner for improving gloss, etc. In other words, the image forming units 30T and 30P form toner images using toner of a special color.

[0013] The image forming section 20 is also provided with an intermediate transfer belt 41 onto which the toner images of each color formed on the photoconductor drums 50 of the image forming units 30 are transferred. The image forming section 20 is also provided with a primary transfer roll 42 that transfers the respective color toner images of the respective image forming units 30 onto the intermediate transfer belt 41 at a primary transfer portion T1. The image forming unit 20 is also provided with a secondary transfer roll 40 that transfers the toner image transferred onto the intermediate transfer belt 41 onto the paper P at a secondary transfer portion T2. Furthermore, the image forming section 20 is provided with a belt cleaner 45 that removes toner and the like from the surface of the intermediate transfer belt 41, and a fixing device 80 that fixes the secondarily transferred image onto the paper P.

[0014] The image forming unit 20 performs an image forming operation based on a control signal from the control unit 21 . Specifically, in the image forming unit 20, first, image processing is performed on the image data input from the image reading device 4 or the PC 5 by the image processing unit 22, and the image data after image processing is supplied to the exposure device 26. Then, for example, in a magenta (M) image forming unit 30M, after the surface of the photosensitive drum 50 is charged by the charging roll 32, the exposure device 26 irradiates the photosensitive drum 50 with laser light modulated by image data obtained from the image processing unit 22.

[0015] As a result, an electrostatic latent image is formed on the photoconductor drum 50 . The formed electrostatic latent image is developed by the developing unit 34, and a magenta toner image is formed on the photosensitive drum 50. Similarly, yellow, cyan and black toner images are formed in the image forming units 30Y, 30C and 30K, and special color toner images are formed in the image forming units 30T and 30P.

[0016] The respective color toner images formed in each image forming unit 30 are electrostatically transferred sequentially by a primary transfer roll 42 onto an intermediate transfer belt 41 rotating in the direction of arrow C in Figure 1, and superimposed toner images are formed on the intermediate transfer belt 41. The superimposed toner image formed on the intermediate transfer belt 41 is transported to a secondary transfer portion T2 constituted by a secondary transfer roll 40 and a backup roll 49 as the intermediate transfer belt 41 moves.

[0017] On the other hand, the paper P is taken out from the first paper storage unit 11 by, for example, the delivery roll 15, and then transported to the position of the registration roll 19 via the transport path. When the superimposed toner image is transported to the secondary transfer portion T2, a sheet of paper P is supplied from the registration roll 19 to the secondary transfer portion T2 in accordance with the transport timing. Then, in the secondary transfer portion T2, the superimposed toner images are electrostatically transferred onto the paper P all at once by the action of a transfer electric field formed between the secondary transfer roll 40 and the backup roll 49.

[0018] Thereafter, the paper P onto which the superimposed toner images have been electrostatically transferred is transported to a fixing device 80. In the fixing device 80, pressure and heat are applied to the paper P on which the unfixed toner image has been formed, and the toner image is fixed to the paper P. Then, the sheet P on which the fixing process has been performed passes through a curl correction section 81 provided in the sheet discharge unit 1C, and is then conveyed to a sheet stacking section (not shown).

[0019] [Explanation of Image Forming Unit 30] Next, the image forming unit 30 to which this embodiment is applied will be described. FIG. 2 is a diagram illustrating a state in which the photoconductor drum 50 is attached to the image forming unit 30. As shown in FIG.

[0020] The image forming unit 30 includes a frame 36 on which various devices such as the photosensitive drum 50 and the developing unit 34 are mounted, and a holder 60 for mounting the photosensitive drum 50 to the frame 36. The holders 60 are provided at both ends (one end and the other end) in the axial direction of the photosensitive drum 50. The holders 60 provided at one end and the holders 60 provided at the other end do not have completely identical shapes, e.g., they have symmetrical portions.

[0021] [Explanation of the photoconductor drum 50] Next, the photoconductor drum 50 will be described in more detail. 3 is a perspective view showing one end side of a photoconductor drum 50 to which this embodiment is applied. The photoconductor drum 50 has a cylindrical photoconductor 51 that functions as an image carrier that carries an electrostatic latent image, and flanges 52 provided on both ends of the photoconductor 51. The photoconductor drum 50 also has a rotating shaft 53 that passes through the center of the photoconductor 51 and is integrated with the flange 52, and bearings 54 provided on both ends of the rotating shaft 53.

[0022] The flanges 52 are provided at the openings on both ends of the photoreceptor 51, and bearings 54 are press-fitted onto the rotary shaft 53. The flanges 52 rotate, and the photoreceptor 51 rotates in conjunction with the rotation of the flanges 52.

[0023] The bearing 54 includes an outer ring 541, an inner ring 542, and a rolling element section 543 that allows the inner ring 542 to rotate relative to the outer ring 541. The outer ring 541 and the inner ring 542 are arranged concentrically. The rolling element section 543 is configured by providing a plurality of rolling elements, for example, spherical or cylindrical. The rotating shaft 53 is press-fitted into the inner ring 542, and the outer ring 541 is fixed to the main body side, so that the photoconductor 51 is held rotatably relative to the main body side.

[0024] [Description of Holder 60] Next, the holder 60 that holds the photosensitive drum 50 will be described. FIG. 4 is a diagram for explaining the holder 60, and is a perspective view showing a state in which the holder 60 is attached to the photosensitive drum 50 in FIG. Holder 60 provided at one end and the other end of photoreceptor drum 50 has handles 61 for a user to grip holder 60, bearing enclosures 62 that come into contact with outer ring 541 of photoreceptor drum 50, and pressing openings 63 that are openings for pressing outer ring 541 from a direction intersecting the axial direction. Also included are installation surfaces 65 for installing holder 60 on frame 36 (see FIG. 2), positioning parts 66 that determine the position of holder 60 relative to frame 36, and fixing parts 67 for fixing holder 60 to frame 36.

[0025] Bearing enclosure 62 surrounds and holds bearing 54 (see FIG. 3) attached to photosensitive drum 50. Bearing enclosure 62 has a cylindrical inner periphery, and the dimension of the inner periphery is the outer periphery dimension of outer ring 541 of bearing 54 plus a clearance dimension that allows attachment and removal of photosensitive drum 50. In other words, a gap is generated between bearing 54, which rotatably supports rotation shaft 53 of photosensitive drum 50, and bearing enclosure 62, which is a member that holds bearing 54.

[0026] The pressing opening 63 is an opening that is opened in the holder 60 in order to press the outer ring 541 in one direction after the holder 60 is attached to the photosensitive drum 50, and exposes a part of the outer ring 541 from the holder 60. The size of the pressing opening 63 is large enough to allow at least a tip portion 721a (see FIG. 5) of a pressing pin 721 (see FIG. 5) of a pressing portion 72 described later to pass through. The installation surface 65 is a surface that comes into contact with the frame 36 when the holder 60 is attached to the frame 36 .

[0027] The positioning portion 66 is a circular through-hole arranged in the installation surface 65. The positioning between the holder 60 and the frame 36 is performed by passing a cylindrical protrusion provided on the frame 36 through the positioning portion 66. The fixing portion 67 is disposed on the installation surface 65 and is a through hole for passing a bolt through. The holder 60 is fixed to the frame 36 with a bolt via this through hole.

[0028] [Description of the pressing unit 72] Next, the pressing portion 72 that presses the outer ring 541 will be described with reference to FIG. FIG. 5 is a cross-sectional view taken along line VV of FIG. 2, showing a state in which the holder 60 on which the photosensitive drum 50 is mounted is attached to the frame . The frame 36 includes a support surface 71 that contacts the mounting surface 65 of the holder 60 to support the holder 60 , and a pressing portion 72 that presses the outer ring 541 .

[0029] The pressing portion 72 includes a pressing pin 721 that presses the outer ring 541 through the pressing opening 63 of the holder 60, and a cylindrical slide portion 722 that moves the pressing pin 721 in one direction. The pressing portion 72 also includes a compression spring 723 that is an example of an elastic member that applies a force in one direction to the pressing pin 721, and a pressing metal plate 724 that serves as a base for the pressing portion 72.

[0030] One end of a compression spring 723 is attached to the pressing pin 721, and the compression spring 723 presses the outer ring 541 by the force of its expansion. The pressure pin 721 has a tip portion 721a that contacts the outer ring 541, and a sliding portion 721b that contacts the inner periphery of the sliding portion 722 in a sliding state. Tip portion 721a is a semispherical protrusion provided at the end of pressing pin 721. When pressing pin 721 comes into contact with outer ring 541, tip portion 721a comes into contact, thereby mitigating the impact on outer ring 541, and for example, preventing outer ring 541 from being scratched. Sliding portion 721b is a cylinder that fits along the inner circumference of slide portion 722 and prevents pressing pin 721 from tilting within slide portion 722. In addition, sliding portion 721b receives compression spring 723 attached to pressing pin 721 so that compression spring 723 does not slip out toward tip portion 721a.

[0031] The slide portion 722 holds the pressing pin 721 so that the pressing pin 721 moves along the inner circumference of the cylinder. The slide portion 722 is disposed so that the center line of the cylinder is extended to position the rotation axis 53 of the photosensitive drum 50 and the rotation axis of the developing roll 33. That is, the pressing pin 721 moves in a direction connecting the axis of the developing roll 33 (see FIG. 1) and the rotation axis 53 of the photosensitive drum 50 (see FIG. 1). The pressing plate 724 is attached to the frame 36 , and the sliding portion 722 and the compression spring 723 are attached to the pressing plate 724 .

[0032] 5 has been described as being attached to the frame 36 on one end side in Fig. 2, but this pressing part 72 is also attached to the frame 36 on the other end side in Fig. 2. The pressing part 72 on the other end side is disposed so as to press the outer ring 541 in the same direction as the pressing direction of the pressing part 72 on the one end side. In other words, the pressing parts 72 provided on both ends of the rotating shaft 53 are disposed so as to press the outer rings 541 on both ends in the same direction.

[0033] [Replace the photoconductor drum 50] Next, the operation of replacing the photosensitive drum 50 will be described with reference to FIGS. When removing the photosensitive drum 50 of the image forming unit 30 shown in FIG. 2 from the frame 36, first, the fixing portion 67 of the holder 60 (see FIG. 4) 2, and remove the photosensitive drum 50 from the frame 36. Then, the handles 61 of both holders 60 are grasped, and the photosensitive drum 50 together with the holders 60 is pulled out to the upper side of FIG. 2 to remove the photosensitive drum 50 from the frame 36. Then, the holders 60 attached to both ends of the photosensitive drum 50 are removed. Then, the holders 60 are attached to both ends of a new photosensitive drum 50, and the photosensitive drum 50 together with the holders 60 are attached to the frame 36.

[0034] When the photosensitive drum 50 is attached to the frame 36, if the holder 60 is moved downward in the up-down direction relative to the frame 36, the lower arc-shaped portion of the bearing enclosure 62 of the holder 60 comes into contact with the tip 721a of the pressing pin 721. Then, as the holder 60 is further lowered, the pressing pin 721 is pressed by the bearing enclosure 62, and the pressing pin 721 moves to the right in the width direction. If the holder 60 moves further downward, the tip 721a of the pressing pin 721 passes through the pressing opening 63 of the holder 60 and moves toward the center in the width direction. As a result, the pressing pin 721 presses the outer ring 541 from the right side toward the center in the width direction.

[0035] 5, the pressing pin 721 passing through the pressing opening 63 provided in the holder 60 presses the outer ring 541 from the right side in the width direction toward the center. Similarly, the pressing pin 721 presses the outer ring 541 on the other end side (see FIG. 2) of the photosensitive drum 50. As a result, the outer rings 541 on both ends of the photosensitive drum 50 are pressed against the bearing enclosure 62 of the holder 60, and movement of the outer ring 541 within the bearing enclosure 62 is suppressed.

[0036] As described above in detail, in the image forming apparatus 1 to which this embodiment is applied, by pressing the outer ring 541 of the photosensitive drum 50, movement of the outer ring 541 caused by the gap between the outer ring 541 and the holder 60 is suppressed, and vibration of the photosensitive drum 50 caused by movement of the rotating shaft 53 is suppressed.

[0037] [Additional Notes] (((1))) A cylindrical image carrier; A rotation shaft for rotating the image carrier; a bearing provided on each end of the rotating shaft, the bearing having an inner ring rotatable relative to an outer ring, the rotating shaft inserted into the inner ring and the inner ring rotating as a unit; a retaining member attached to a main body side and retaining the outer ring of the bearing; a pressing portion that presses the outer ring of the bearing in one direction to press the outer ring against the holding member; An image forming apparatus comprising: (((2))) The image forming apparatus described in (((1))) is characterized in that after the holding member is attached to the main body, the outer ring of the bearing is pressed in the one direction. (((3))) a developer holder that is provided along the axial direction of the image holder attached to the main body side and develops the image holder, The image forming apparatus described in (((1))) or (((2))) is characterized in that the one direction in which the pressing portion presses the outer ring is a direction connecting an axis of the developer carrier and an axis of the image carrier. (((4))) The image forming apparatus according to any one of ((1))) to (((3))), wherein the pressing portion presses using an elastic member. (((5))) The image forming apparatus according to any one of ((1)) to ((4))), wherein the retaining member includes a surrounding portion that surrounds the outer ring of the bearing and is removable from the outer ring. (((6))) the surrounding portion has an opening through which a portion of the outer ring is exposed, The image forming apparatus according to (((5))) is characterized in that the pressing portion presses the outer ring through the opening. (((7))) The image forming apparatus according to any one of ((1))) to (((6))), wherein the pressing portion is provided on the main body side. (((8))) The holding members are provided on both ends of the rotating shaft, The image forming apparatus described in (((7))) is characterized in that the pressing portion presses the outer ring in the same direction at both ends of the rotating shaft.

[0038] According to the image forming apparatus of (((1))), vibration of the image carrier is suppressed even when a gap is generated between a bearing that rotatably supports the rotation shaft of the image carrier and a member that holds the bearing. According to the image forming apparatus of (((2))), the alignment between the device on the main body and the image carrier can be determined more accurately than in a configuration in which the bearings are pressed before the image carrier is attached to the main body. According to the image forming device of (((3))), the positional accuracy of the image carrier relative to the developer carrier is improved and printing defects are suppressed, compared to a case in which the direction in which the pressing portion presses the outer ring is determined regardless of the position of the developer carrier. According to the image forming apparatus of (((4))), the position of the axis of the image carrier is prevented from fluctuating before and after replacement of the image carrier, as compared to a case in which the pressing force of the pressing portion is determined by the user. According to the image forming apparatus of (((5))), resources used when replacing the image carrier are reduced compared to when the holding member is not detachable from the image carrier. According to the image forming apparatus of (((6))), the load on the bearing is suppressed compared to a case where the bearing is pressed in a direction inclined with respect to the rotation shaft. According to the image forming apparatus of (((7))), the position of the axis of the image carrier and the positional relationship with the device on the main body side can be determined with greater precision than when a pressing portion is provided on the holding member. According to the image forming apparatus of (((8))), tilt of the image carrier is suppressed compared to a case in which the outer ring is pressed in different directions at both ends of the rotation shaft. [Explanation of symbols]

[0039] Reference Signs List 1...image forming apparatus, 30...image forming unit, 33...developing roll, 34...developing device, 36...frame, 50...photosensitive drum, 51...photosensitive body, 52...flange, 53...rotating shaft, 54...bearing, 60...holder, 62...bearing enclosure, 63...pressing opening, 72...pressing portion, 541...outer ring, 542...inner ring, 543...rolling body portion, 721...pressing pin, 721a...tip portion, 721b...sliding portion, 722...slide portion, 723...compression spring, 724...pressing plate

Claims

1. A cylindrical image carrier; A rotation shaft for rotating the image carrier; a bearing provided on each end of the rotating shaft, the bearing having an inner ring rotatable relative to an outer ring, the rotating shaft inserted into the inner ring and the inner ring rotating as a unit; a retaining member attached to a main body side and retaining the outer ring of the bearing; a pressing portion that presses the outer ring of the bearing in one direction to press the outer ring against the holding member; An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, wherein the outer ring of the bearing is pressed in the one direction after the holding member is attached to the main body.

3. a developer holder that is provided along the axial direction of the image holder attached to the main body side and develops the image holder, 3. The image forming apparatus according to claim 2, wherein the one direction in which the pressing portion presses the outer ring is a direction connecting an axis of the developer carrier and an axis of the image carrier.

4. 4. The image forming apparatus according to claim 3, wherein the pressing portion presses using an elastic member.

5. The image forming apparatus according to claim 1 , wherein the holding member includes a surrounding portion that surrounds the periphery of the outer ring of the bearing and is detachable from the outer ring.

6. the surrounding portion has an opening through which a portion of the outer ring is exposed, The image forming apparatus according to claim 5 , wherein the pressing portion presses the outer ring through the opening.

7. The image forming apparatus according to claim 1 , wherein the pressing portion is provided on the main body side.

8. The holding members are provided on both ends of the rotating shaft, 8. The image forming apparatus according to claim 7, wherein the pressing portion presses the outer ring in the same direction at both ends of the rotation shaft.

Images