Image forming apparatus

Abstract

To move a belt unit located at an incompletely mounted position to a completely mounted position by means of a drum unit.SOLUTION: At least one of a first side frame 151 and a second side frame 152 has a first inclined surfaces 151S, 152S. When a drum unit is mounted in a housing in a state where a belt unit is at an incompletely mounted position shifted to the other side in a second direction from a completely mounted position in which the belt unit is mounted in the housing, a roller cover 160 and the belt unit do not come into contact, but the belt unit moves from the incompletely mounted position to the completely mounted position with pressing of the belt unit by the first inclined surfaces 151S, 152S.SELECTED DRAWING: Figure 6

Description

[Technical Field]

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

[0002] Conventionally, there is known an image forming apparatus in which a belt unit having an endless belt can be attached to and detached from the apparatus main body (Patent Document 1). In this image forming apparatus, when a drum unit having a photosensitive drum is attached to a state in which the belt unit is in an incompletely attached position (referred to as an "incompletely attached position"), the drum unit abuts against the belt unit and pushes the belt unit downward to position it in the completely attached position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-046251 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the drum unit is equipped with a cleaning roller that contacts the photosensitive drum and a roller cover that covers the cleaning roller, the roller cover may interfere with the belt unit, preventing the drum unit from pushing the belt unit to the fully installed position.

[0005] Therefore, an object of the present disclosure is to make it possible to push a belt unit that is in an incomplete installation position to a complete installation position by using the drum unit, even when the drum unit has a roller cover. [Means for solving the problem]

[0006] To achieve the above-mentioned object, the image forming apparatus of the first disclosure includes a housing, a drum unit, and a belt unit. The housing has an opening. The drum unit is detachably attached to the housing through the opening and includes a first side frame, a second side frame, a photosensitive drum, a cleaning roller, and a roller cover. The second side frame faces the first side frame in the first direction. The photosensitive drum extends in a first direction and is located between the first side frame and the second side frame in the first direction. The cleaning roller comes into contact with the peripheral surface of the photosensitive drum and cleans the peripheral surface of the photosensitive drum. The roller cover covers the cleaning roller. The belt unit is located on one side of the photosensitive drum in a second direction intersecting the first direction, and has an endless belt that can come into contact with the photosensitive drum. At least one of the first side frame and the second side frame has a first inclined surface, and when the drum unit is installed in the housing with the belt unit in an incomplete installation position that is shifted to the other side in the second direction from the complete installation position where the belt unit is installed in the housing, the roller cover and the belt unit do not come into contact with each other, and the first inclined surface pushes the belt unit, causing the belt unit to move from the incomplete installation position to the complete installation position.

[0007] When the drum unit is attached to the housing while the belt unit is in the incomplete installation position, the roller cover does not come into contact with the belt unit, so the first inclined surface pushes the belt unit, allowing the belt unit to move from the incomplete installation position to the complete installation position.

[0008] The second disclosure may be the first disclosure, wherein the first inclined surface is inclined with respect to the mounting direction so that the more downstream in the mounting direction the drum unit is mounted to the housing, the more to the other side of the second direction it is positioned.

[0009] In a third disclosure, in the first disclosure, the belt unit may have a second inclined surface that can come into contact with the first inclined surface. The second inclined surface may be inclined with respect to the mounting direction so that the second inclined surface is positioned on the other side of the second direction as it moves downstream in the mounting direction in which the drum unit is mounted to the housing.

[0010] In a fourth disclosure, in the third disclosure, the second inclined surface may have an opening, and when the belt unit is in the installation complete position and the drum unit is installed in the housing, a part of the drum unit may fit into the opening.

[0011] By having a part of the drum unit enter the opening of the second inclined surface, space can be used effectively, and the image forming apparatus can be made smaller.

[0012] In a fifth disclosure, in the first disclosure, the roller cover may hold a light guide that guides light to the photosensitive drum and neutralizes the circumferential surface of the photosensitive drum.

[0013] In a sixth disclosure, in the first disclosure, the drum unit may further include a first bearing and a second bearing that rotatably support the cleaning roller. The roller cover may have an arc wall extending in an arc shape along the circumferential surface of the cleaning roller, a first retaining wall extending from one end of the arc wall in the first direction and holding the first bearing, and a second retaining wall extending from the other end of the arc wall in the first direction and holding the second bearing. The first retaining wall and the second retaining wall may protrude downstream of the arc wall in an installation direction in which the drum unit is installed in the housing.

[0014] In a seventh disclosure, in the sixth disclosure, the belt unit may further include a handle located at an upstream end in the mounting direction. The handle may be located between the first retaining wall and the second retaining wall in the first direction.

[0015] By positioning the handle between the first holding wall and the second holding wall, the handle is less likely to come into contact with the roller cover.

[0016] In an eighth disclosure, in the sixth disclosure, the roller cover may have a first wall, a second wall, and a third wall. The first wall protrudes downstream in the mounting direction from the other end of the arc wall in the second direction and extends in the first direction. The second wall protrudes from one end of the arc wall on one side in the second direction in the second direction and extends in the first direction. The third wall extends from one end of the second wall in the second direction to the upstream side and the downstream side in the installation direction.

[0017] By having the first wall, the second wall, and the third wall, the roller cover can have high rigidity.

[0018] In a ninth disclosure, in the sixth to eighth disclosures, it is desirable that the outer surface of the arc wall does not have any protrusions.

[0019] Since the outer surface of the arc wall does not have any protrusions, the belt unit is less likely to come into contact with the roller cover.

[0020] In a tenth disclosure, in the first disclosure, the roller cover may be located at a downstream end of the drum unit in an attachment direction in which the drum unit is attached to the housing.

[0021] According to an eleventh disclosure, in the first disclosure, the center of the roller cover in the first direction may be located more upstream in the mounting direction in which the drum unit is mounted to the housing than both end portions in the first direction. [Effects of the Invention]

[0022] According to the present disclosure, even when the drum unit has a roller cover, the belt unit that is in the incomplete installation position can be pushed to the complete installation position by the drum unit. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 2 is a cross-sectional view of the image forming apparatus. [Figure 2] FIG. 2 is a cross-sectional view of the drum unit. [Figure 3] FIG. 2 is an exploded perspective view of some parts of the drum unit. [Figure 4] FIG. 2A is a perspective view of a roller cover, and FIG. 2B is an enlarged cross-sectional view of the cleaning roller and its surroundings. [Figure 5] 10A and 10B are diagrams illustrating the positional relationship between the drum unit and the belt unit when the drum unit is attached to the housing. [Figure 6] FIG. 2 is a perspective view of the drum unit as seen from one side in the second direction. [Figure 7] FIG. 2 is a perspective view of a belt unit. [Figure 8] 1A is a cross-sectional view of the image forming apparatus when the drum unit starts to push the belt unit that is in an incomplete installation position, and FIG. 1B is an enlarged cross-sectional view of the vicinity of the roller cover in the center portion in the first direction of FIG. [Figure 9] 10 is a cross-sectional view of the image forming apparatus when the drum unit pushes the belt unit and the belt unit is positioned at the installation completion position. FIG. [Figure 10] 10A is a perspective view of the belt unit and drum unit after installation, seen from one side in the second direction, and FIG. 10B is a partially enlarged cross-sectional view passing through the positioning guide of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] Next, an embodiment of the present disclosure will be described in detail with reference to the drawings as appropriate. As shown in FIG. 1, the image forming apparatus 1 includes a housing 10, a sheet supply unit 20, an image forming unit 30, and a sheet discharge unit 90.

[0025] In the following description, the axial direction of the photosensitive drum 51 is referred to as the first direction (see FIG. 5). The direction intersecting the first direction is referred to as the second direction. Preferably, the second direction is perpendicular to the first direction. The direction intersecting the first and second directions is referred to as the third direction. Preferably, the third direction is perpendicular to the first and second directions. In the first, second, and third directions, the direction indicated by the arrow in each drawing is referred to as one side, and the direction opposite to the arrow is referred to as the other side. For example, in FIG. 1, the bottom is one side of the second direction, and the top is the other side of the second direction. The right is one side of the third direction, and the left is the other side of the third direction.

[0026] The housing 10 has an opening 10A on the other side in the third direction. The housing 10 has a cover 11 at the end on the other side in the third direction. The cover 11 can open and close the opening 10A. The housing 10 has a discharge tray 12 on the other side.

[0027] The sheet supply unit 20 includes a sheet tray 21 that stores sheets S such as paper, a pickup roller 22, a separation roller 23, a separation pad 24, a conveyance roller 25, and a second conveyance roller 26.

[0028] The sheet supply unit 20 feeds out the sheets S in the sheet tray 21 using a pickup roller 22, and separates the sheets one by one using a separation roller 23 and a separation pad 24. Then, the sheet supply unit 20 conveys the sheets S toward the photosensitive drum 51 using a conveyance roller 25, a second conveyance roller 26, and a first conveyance roller 110, which will be described later.

[0029] The second conveying roller 26 is a roller that rotates when a driving force is input. The second conveying roller 26 is held in the housing 10. The leading edge of the sheet S comes into contact with the second conveying roller 26, thereby determining the position of the leading edge of the sheet S. The second conveying roller 26 conveys the sheet S, whose leading edge has been positioned, toward the photosensitive drum 51.

[0030] The image forming section 30 includes an exposure device 40, a drum unit 50, a plurality of toner cartridges 60, a belt unit 70, and a fixing device 80.

[0031] The exposure device 40 is located on the other side in the second direction within the housing 10 relative to the drum unit 50. The exposure device 40 exposes the surface of the photosensitive drum 51 by emitting a plurality of light beams indicated by dashed dotted lines.

[0032] The drum unit 50 includes multiple photosensitive drums 51, multiple chargers 52, multiple cleaning rollers 120 (see FIG. 2), a drum frame 150, and multiple roller covers 160 (see FIG. 2). By opening the cover 11, the drum unit 50 can be attached to and detached from the housing 10 of the image forming apparatus 1 in the third direction through the opening 10A. The drum unit 50 is attached from the other side to one side in the third direction. Hereinafter, the attachment direction of the drum unit 50, that is, the direction from the other side to one side in the third direction, will also be simply referred to as the "attachment direction." When attached to the housing 10, the drum unit 50 is located between the sheet tray 21 and the exposure device 40. A toner cartridge 60 can be attached to and detached from the drum unit 50 (see FIG. 2). The drum unit 50 can be attached to and detached from the housing 10 with the toner cartridge 60 attached.

[0033] As shown in FIGS. 2 and 3, the drum frame 150 includes a first side frame 151, a second side frame 152, a first connecting frame 153, a second connecting frame 154, and a charger frame 155.

[0034] The first side frame 151 and the second side frame 152 are positioned apart in the first direction. The first side frame 151 and the second side frame 152 face each other in the first direction. The first connecting frame 153 connects one end of the first side frame 151 to one end of the second side frame 152 in the third direction. The second connecting frame 154 connects the other end of the first side frame 151 to the other end of the second side frame 152 in the third direction. The charging frame 155 is provided corresponding to each of the multiple photosensitive drums 51. The charging frame 155 holds the charger 52, the cleaning roller 120, and the roller cover 160. The charging frame 155 is positioned between the first connecting frame 153 and the second connecting frame 154. The charging frame 155 connects the first side frame 151 to the second side frame 152.

[0035] The photosensitive drum 51 extends in the first direction. The photosensitive drum 51 is located between the first side frame 151 and the second side frame 152 in the first direction. The photosensitive drum 51 is rotatable about a first shaft 51X extending in the first direction. The multiple photosensitive drums 51 are lined up in the third direction. Four photosensitive drums 51 are provided corresponding to the colors of image formation. The photosensitive drums 51 are arranged from the other side to one side in the third direction as photosensitive drums 51Y, 51M, 51C, and 51K corresponding to yellow, magenta, cyan, and black.

[0036] 2, the chargers 52 are provided corresponding to the plurality of photosensitive drums 51, respectively. The chargers 52 face the photosensitive drums 51.

[0037] The cleaning roller 120 is a roller that cleans the circumferential surface of the photosensitive drum 51. The roller cover 160 is a cover that covers the cleaning roller 120. The cleaning roller 120 and the roller cover 160 will be described in detail later.

[0038] The toner cartridge 60, while attached to the drum unit 50, can be detachably attached to the housing 10 together with the drum unit 50. The multiple toner cartridges 60 contain toner of different colors, for example, yellow, magenta, cyan, and black. The toner cartridge 60 includes a developing roller 61, a supply roller 62, a layer thickness regulating blade 63, a toner storage section 64 that stores toner, and an agitator 65.

[0039] The toner cartridge 60 supplies the toner in the toner storage section 64 to the supply roller 62 while stirring it with the agitator 65, and then supplies it from the supply roller 62 to the developing roller 61. Then, as the developing roller 61 rotates, the toner supplied to the developing roller 61 enters between the developing roller 61 and the layer thickness regulating blade 63, and is carried by the developing roller 61 at a constant thickness.

[0040] As shown in FIG. 1, the belt unit 70 is located between the sheet tray 21 and the drum unit 50 attached to the housing 10. That is, the belt unit 70 is located on one side of the photosensitive drum 51 in the second direction. The belt unit 70 includes a drive roller 71, a driven roller 72, a conveyor belt 73, multiple transfer rollers 74, a belt frame 75 (see FIG. 5), and a handle 76. The belt frame 75 holds the drive roller 71, the driven roller 72, the conveyor belt 73, and the transfer roller 74. The drive roller 71 and the driven roller 72 are spaced apart in the third direction. The conveyor belt 73 is an endless belt. The conveyor belt 73 can come into contact with the photosensitive drum 51. The conveyor belt 73 is stretched between the drive roller 71 and the driven roller 72. The transfer roller 74 is located inside the conveyor belt 73 and sandwiches the conveyor belt 73 between the drive roller 71 and the driven roller 72. The handle 76 is located at the other end of the belt unit 70 in the third direction. That is, the handle 76 is located at the upstream end of the belt unit 70 in the installation direction of the drum unit 50. The handle 76 is fixed to the belt frame 75.

[0041] The belt unit 70 is attachable to and detachable from the housing 10 in the third direction through the opening 10A. Specifically, with the drum unit 50 removed from the housing 10, the belt unit 70 is attachable to and detachable from the housing 10 through the space in which the drum unit 50 is installed. When the belt unit 70 is completely installed in the housing 10, it is located at the installation completion position shown in FIG. 1. On the other hand, if the installation of the belt unit 70 is incomplete, the belt unit 70 may be located at an installation incomplete position that is shifted to the other side in the second direction from the installation completion position (see FIGS. 8(a) and (b)).

[0042] The fixing device 80 includes a heating roller 81 that heats the sheet S, and a pressure roller 82. The pressure roller 82 is pressed against the heating roller 81.

[0043] The image forming unit 30 charges the surface of the photosensitive drum 51 using the charger 52. Then, the image forming unit 30 exposes the surface of the photosensitive drum 51 using the exposure device 40. As a result, an electrostatic latent image is formed on the photosensitive drum 51. Next, the image forming unit 30 supplies toner from the development roller 61 to the photosensitive drum 51. As a result, the electrostatic latent image on the photosensitive drum 51 is made visible, and a toner image is formed on the photosensitive drum 51.

[0044] Next, the image forming unit 30 transfers the toner image on the photosensitive drum 51 onto the sheet S by transporting the sheet S supplied from the sheet supply unit 20 between the photosensitive drum 51 and the transfer roller 74. Then, the image forming unit 30 transports the sheet S onto which the toner image has been transferred between the heating roller 81 and the pressure roller 82, thereby thermally fixing the toner image onto the sheet S and forming an image on the sheet S.

[0045] The sheet discharge section 90 has a conveying roller 91 and a discharge roller 92. The conveying roller 91 conveys the sheet S on which an image has been formed toward the discharge roller 92. The discharge roller 92 discharges the sheet S onto the discharge tray 12 of the housing 10.

[0046] As shown in FIG. 2, the drum unit 50 further includes a paper dust cleaning section CL.

[0047] The paper dust cleaning unit CL collects paper dust adhering to the sheet S. The paper dust cleaning unit CL includes a first conveyor roller 110, a paper dust container 115, and a friction charging member 118.

[0048] The first conveying roller 110 is a roller that can rotate about a second shaft 110X that extends in the first direction. The first conveying roller 110 is located at the other end of the drum frame 150 in the third direction. The first conveying roller 110 is located upstream of the multiple photosensitive drums 51 in the conveying direction of the sheet S.

[0049] The first conveying roller 110 conveys the sheet S toward the photosensitive drum 51. More specifically, when the drum unit 50 is attached to the housing 10 of the image forming apparatus 1, the first conveying roller 110 comes into contact with the second conveying roller 26 of the image forming apparatus 1, and sandwiches the sheet S between the first conveying roller 110 and the second conveying roller 26 to convey the sheet S toward the photosensitive drum 51. The first conveying roller 110 sends out the sheet S sandwiched between the first conveying roller 110 and the second conveying roller 26 toward one side in the third direction.

[0050] Here, the drum frame 150 has positioning guides 159 at positions close to the first conveyor roller 110. The positioning guides 159 are located at both ends of the drum frame 150 in the first direction. When viewed along the first direction, the positioning guides 159 protrude toward the second conveyor roller 26. The positioning guides 159 have a U-shaped opening that opens toward one side in the second direction and receives the second conveyor roller 26. More specifically, the positioning guides 159 fit into bearings 26U of the second conveyor roller 26 to position the first conveyor roller 110 with respect to the second conveyor roller 26.

[0051] The first conveyor roller 110 is configured to have a roller body made of metal and a coating layer made of fluororesin that covers the outer circumferential surface of the roller body.

[0052] The first conveyor roller 110 is capable of collecting paper dust from the sheet S being conveyed between the first conveyor roller 110 and the second conveyor roller 26. More specifically, the first conveyor roller 110 is capable of collecting the paper dust on the sheet S by electrically attracting it. Specifically, the outer circumferential surface of the first conveyor roller 110 is charged to a polarity opposite to the charging characteristics of the paper dust by contact with the frictional charging member 118, thereby electrically attracting and collecting the paper dust on the sheet S.

[0053] The frictional charging member 118 comes into contact with the first conveyor roller 110 to charge the outer circumferential surface of the first conveyor roller 110, and also scrapes the paper dust collected by the first conveyor roller 110 from the first conveyor roller 110. The paper dust scraped off from the first conveyor roller 110 is stored in the paper dust storage unit 115.

[0054] Next, the configuration around the cleaning roller 120 and the configuration for pushing the belt unit 70 from the incomplete installation position to the complete installation position by the drum unit 50 will be described.

[0055] As shown in FIGS. 3 and 4, the cleaning roller 120 is rotatable about a third axis 120X extending in the first direction. The cleaning roller 120 has a shaft 121 and a roller body 122. The shaft 121 is made of metal. The roller body 122 covers the shaft 121. The roller body 122 is made of rubber. The cleaning roller 120 is in contact with the circumferential surface of the photosensitive drum 51. The cleaning roller 120 rotates in response to the photosensitive drum 51, and is capable of collecting paper dust on the circumferential surface of the photosensitive drum 51. More specifically, the cleaning roller 120 is capable of collecting paper dust on the photosensitive drum 51 by electrically attracting the paper dust by applying an electrical bias to the shaft 121.

[0056] The drum unit 50 further includes a first bearing 165A, a second bearing 165B, and a light guide 55. The first bearing 165A and the second bearing 165B each rotatably support the cleaning roller 120. Specifically, the first bearing 165A supports an end 121A on one side in the first direction of the shaft 121, and the second bearing 165B supports an end 121B on the other side in the first direction of the shaft 121. The light guide 55 guides light to the photosensitive drum 51 to neutralize the circumferential surface of the photosensitive drum 51.

[0057] The roller cover 160 covers the circumferential surface of the cleaning roller 120. The roller cover 160 corresponding to the black photosensitive drum 51K is located at the downstream end of the drum unit 50 in the installation direction in which the drum unit 50 is installed in the housing. The roller cover 160 has an arc wall 161, a first retaining wall 162A, a second retaining wall 162B, a first wall 163, a second wall 164, a third wall 165, and a recess 169.

[0058] The arc wall 161 extends in an arc shape along the circumferential surface of the cleaning roller 120. The first retaining wall 162A extends from one end of the arc wall 161 in the first direction in a direction intersecting the first direction. The arc wall 161 has an outer surface that extends in an arc shape. The outer surface of the arc wall 161 does not have any protrusions.

[0059] The first retaining wall 162A retains the first bearing 165A. The second retaining wall 162B extends from the other end of the arc wall 161 in the first direction in a direction intersecting the first direction. The second retaining wall 162B retains the second bearing 165B. The first retaining wall 162A and the second retaining wall 162B protrude further downstream in the mounting direction in which the drum unit 50 is mounted to the housing 10 than the arc wall 161. Therefore, the center of the roller cover 160 is located more upstream in the mounting direction in which the drum unit 50 is mounted to the housing 10 than the both ends in the first direction.

[0060] The first wall 163 protrudes downstream in the mounting direction from the other end of the arc wall 161 in the second direction. The first wall 163 extends in the first direction. The second wall 164 protrudes from one end of the arc wall 161 in the second direction toward one side in the second direction. The second wall 164 extends in the first direction. The third wall 165 extends from one end of the second wall 164 in the second direction to the upstream side and downstream side in the installation direction.

[0061] The recess 169 is a recess that opens toward the other side in the third direction. The recess 169 is formed by the arc wall 161, the second wall 164, and the third wall 165. The roller cover 160 holds the light guide 55 in the recess 169.

[0062] The arc wall 161, and the first wall 163, third wall 165, first retaining wall 162A, and second retaining wall 162B surrounding the arc wall 161, give the roller cover 160 a recessed shape when viewed from the outside. The arc wall 161 does not have any protrusions on its outer circumferential surface. Therefore, the arc wall 161 is less likely to interfere with the handle 76 of the belt unit 70, as will be described later.

[0063] 5 is a diagram showing the positional relationship between the drum unit 50 and the belt unit 70 when the drum unit 50 is attached to the housing 10. As shown in FIG. 5, the handle 76 of the belt unit 70 is located between the first retaining wall 162A and the second retaining wall 162B in the first direction. The drum unit 50 has first inclined surfaces 151S and 152S on the first side frame 151 and the second side frame 152, respectively.

[0064] 6, the first inclined surface 151S is located at the end of the first side frame 151 on the downstream side in the mounting direction and on one side in the second direction. The first inclined surface 151S is a flat surface. The first inclined surface 151S is inclined with respect to the mounting direction so that the more downstream in the mounting direction the surface is positioned on the other side in the second direction. The first inclined surface 152S is located at the end of the second side frame 152 on the downstream side in the mounting direction and on one side in the second direction. The first inclined surface 152S is flat. The first inclined surface 152S is inclined with respect to the mounting direction so that the more downstream in the mounting direction the first inclined surface 152S is located on the other side in the second direction. When viewed along the first direction, the first inclined surface 152S is located at approximately the same position as the first inclined surface 151S.

[0065] 4(a), the first inclined surface 151S is located on one side in the second direction relative to the roller cover 160. Similarly, the first inclined surface 152S is located on one side in the second direction relative to the roller cover 160.

[0066] As shown in FIG. 7, the belt unit 70 has second inclined surfaces 171S and 172S on the belt frame 75. In the following description of the belt unit 70, the directions are based on the state in which the belt unit 70 is fully installed in the housing 10. The belt frame 75 has a first side frame 75A and a second side frame 75B that are spaced apart from each other in the first direction. The second side frame 75B is spaced apart from the first side frame 75A on the other side in the first direction. The conveyor belt 73 is located between the first side frame 75A and the second side frame 75B. The second inclined surface 171S is located at the end of the first side frame 75A on the other side in the third direction and at the other end of the first side frame 75A on the other side in the second direction. The second inclined surface 171S is inclined with respect to the installation direction so that it is located closer to the other side in the second direction as it approaches the downstream side in the installation direction. The second inclined surface 172S is located at the other end of the second side frame 75B in the third direction and at the other end in the second direction. The second inclined surface 172S is inclined with respect to the mounting direction so that the more downstream in the mounting direction the second inclined surface 172S is located, the more to the other side in the second direction.

[0067] The second inclined surface 171S can come into contact with the first inclined surface 151S when the drum unit 50 is attached to the housing 10. The second inclined surface 172S can come into contact with the first inclined surface 152S when the drum unit 50 is attached to the housing 10.

[0068] Second inclined surface 172S, which is located on the other side in the first direction, has opening 175. Opening 175 is open toward the other side in the second direction and the other side in the third direction. When belt unit 70 is in the installation completion position and drum unit 50 is installed in housing 10, positioning guide 159, which is part of drum unit 50, fits into opening 175 (see FIG. 10(b)).

[0069] In the image forming apparatus 1 configured as above, a case where the belt unit 70 and the drum unit 50 are attached to the housing 10 will be described. 8(a) and 8(b), when attaching the belt unit 70 to the housing 10, the user grasps the handle 76 and inserts the belt unit 70 into the housing 10 through the opening 10A of the housing 10. Then, the user lowers the belt unit 70 to one side in the second direction. If the user does not perform the work properly, the end of the belt unit 70 on the handle 76 side may be raised, resulting in an incomplete attachment position.

[0070] When the drum unit 50 is installed in the housing 10 with the belt unit 70 in the incomplete installation position, the first inclined surfaces 151S and 152S of the drum unit 50 come into contact with the second inclined surfaces 171S and 172S. The first inclined surfaces 151S and 152S then push the second inclined surfaces 171S and 172S toward one side in the second direction, moving the belt unit 70 toward one side in the second direction. When the drum unit 50 is further inserted into the housing 10 and the first inclined surfaces 151S and 152S are positioned toward one side in the third direction relative to the second inclined surfaces 171S and 172S, the belt unit 70 is positioned in the complete installation position, as shown in FIG. 9. During this process, as shown in FIG. 8(b), the handle 76 of the belt unit 70 enters between the first retaining wall 162A and the second retaining wall 162B of the roller cover 160 but does not come into contact with the roller cover 160.

[0071] 10(a) and 10(b), when the drum unit 50 is positioned at the installation completion position, the end 159A of the positioning guide 159 of the drum unit 50 enters the opening 175 of the belt frame 75.

[0072] In this way, in the image forming apparatus 1 of this embodiment, when the drum unit 50 is attached to the housing 10 while the belt unit 70 is in the incomplete installation position, the roller cover 160 and the belt unit 70 do not come into contact with each other, and therefore the first inclined surfaces 151S, 152S press the second inclined surfaces 171S, 172S of the belt unit 70, thereby moving the belt unit 70 from the incomplete installation position to the complete installation position.

[0073] If the roller cover 160 and the belt unit 70 were to come into contact with each other, the roller cover 160 would be deformed, causing the inner surface of the roller cover 160 to come into contact with the cleaning roller 120 and potentially damaging the surface of the cleaning roller 120. Furthermore, in this case, the cleaning roller 120 and the photosensitive drum 51 would be subjected to an impact, potentially damaging the cleaning roller 120 or the photosensitive drum 51. Furthermore, the position of the ride guide 55 relative to the photosensitive drum 51 would be shifted, potentially preventing the surface of the photosensitive drum 51 from being properly neutralized. Meanwhile, in the image forming apparatus 1 of this embodiment, when the drum unit 50 is installed in the housing 10 with the belt unit 70 in the incomplete installation position, the roller cover 160 and the belt unit 70 do not come into contact with each other, thereby reducing the possibility of the surface of the cleaning roller 120 being scratched, the cleaning roller 120 or the photosensitive drum 51 being damaged, or the ride guide being shifted.

[0074] Furthermore, by allowing a portion of the belt unit 70 to fit into the opening 175 of the second inclined surface 172S, the space can be used effectively, and the image forming apparatus 1 can be made smaller.

[0075] Furthermore, since the handle 76 is located between the first retaining wall 162A and the second retaining wall 162B, the handle 76 is less likely to come into contact with the roller cover 160.

[0076] Furthermore, since the roller cover 160 has the first wall 163, the second wall 164, and the third wall 165, the rigidity of the roller cover 160 can be increased.

[0077] Furthermore, since the outer surface of the arc wall 161 does not have any protrusions, the belt unit 70 can be prevented from coming into contact with the roller cover 160 except for the second inclined surfaces 171S and 172S.

[0078] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above-described embodiment and can be implemented with appropriate modifications.

[0079] For example, in the above embodiment, the belt unit has an endless belt for transporting a sheet, but the endless belt of the belt unit may be an intermediate transfer belt onto which a toner image is transferred from a photosensitive drum.

[0080] In the above embodiment, the roller cover has a first wall, a second wall, and a third wall, but it does not have to have a third wall. Even if the roller cover has at least one of the first wall and the second wall in addition to the arc wall, it is possible to increase the rigidity of the roller cover. Also, the roller cover does not have to have any of the first wall, the second wall, and the third wall.

[0081] In the above embodiment, both the first side frame and the second side frame have the first inclined surface, but only one of the first side frame and the second side frame may have the first inclined surface. That is, it is sufficient that at least one of the first side frame and the second side frame has the first inclined surface.

[0082] The belt unit does not necessarily have to have the second inclined surface, and may be configured such that, for example, the first inclined surface comes into contact with a corner of the belt unit.

[0083] In the above-described embodiment, an image forming apparatus and drum unit are illustrated as having four photosensitive drums and printing color images using four color toners, but the image forming apparatus and drum unit may be configured to print color images using three or five color toners, for example. The image forming apparatus and drum unit may also be configured to have only one photosensitive drum and print monochrome images. The image forming apparatus may also be a printer, or a multifunction peripheral or copier equipped with a document reading device such as a flatbed scanner.

[0084] Furthermore, the elements described in the above-described embodiment and modifications can be implemented in appropriate combinations. [Explanation of symbols]

[0085] 1. Image forming device 10. Cabinet 10A aperture 50 drum unit 51 Photosensitive drum 70 Belt unit 73 Conveyor belt 76 Handle 120 Cleaning roller 150 drum frame 151 First side frame 151S,152S 1st slope 152 Second side frame 160 Roller cover

Claims

1. a housing having an opening; a drum unit that is detachable from the housing through the opening, A first side frame; a second side frame facing the first side frame in a first direction; a photosensitive drum extending in the first direction and positioned between the first side frame and the second side frame in the first direction; a cleaning roller that comes into contact with the peripheral surface of the photosensitive drum and cleans the peripheral surface of the photosensitive drum; a roller cover that covers the cleaning roller; a drum unit having a belt unit located on one side of the photosensitive drum in a second direction intersecting the first direction, the belt unit having an endless belt capable of contacting the photosensitive drum; At least one of the first side frame and the second side frame has a first inclined surface, An image forming apparatus characterized in that when the drum unit is attached to the housing while the belt unit is positioned in an incomplete installation position that is shifted to the other side in the second direction from the complete installation position at which the belt unit is attached to the housing, the roller cover and the belt unit do not come into contact with each other, and the first inclined surface presses the belt unit, causing the belt unit to move from the incomplete installation position to the complete installation position.

2. 2. The image forming apparatus according to claim 1, wherein the first inclined surface is inclined with respect to the mounting direction so that the more downstream in the mounting direction the drum unit is mounted to the housing, the more it is positioned on the other side of the second direction.

3. 2. The image forming apparatus according to claim 1, wherein the belt unit has a second inclined surface that can contact the first inclined surface, and the second inclined surface is inclined with respect to the mounting direction so that the downstream side of the mounting direction in which the drum unit is mounted to the housing is positioned on the other side of the second direction.

4. the second inclined surface has an opening; 4. The image forming apparatus according to claim 3, wherein when the belt unit is in the installation complete position and the drum unit is installed in the housing, a portion of the drum unit fits into the opening.

5. 2. The image forming apparatus according to claim 1, wherein the roller cover holds a light guide that guides light to the photosensitive drum to neutralize the peripheral surface of the photosensitive drum.

6. the drum unit further includes a first bearing and a second bearing that rotatably support the cleaning roller; The roller cover is an arc wall extending in an arc shape along the circumferential surface of the cleaning roller; a first retaining wall extending from one end of the arc wall in the first direction and configured to retain the first bearing; a second retaining wall extending from the other end of the arc wall in the first direction and configured to retain the second bearing; 2. The image forming apparatus according to claim 1, wherein the first holding wall and the second holding wall protrude downstream of the arc wall in a mounting direction in which the drum unit is mounted in the housing.

7. the belt unit further includes a handle located at an upstream end in the mounting direction; 7. The image forming apparatus according to claim 6, wherein the handle is located between the first holding wall and the second holding wall in the first direction.

8. The roller cover is a first wall that protrudes from the other end of the arc wall in the second direction downstream in the mounting direction and extends in the first direction; a second wall that protrudes from an end of the arc wall on one side in the second direction in the second direction and extends in the first direction; a third wall extending from one end of the second wall in the second direction to the upstream side and the downstream side in the mounting direction; 7. The image forming apparatus according to claim 6, further comprising:

9. 9. The image forming apparatus according to claim 6, wherein the outer surface of the arc wall does not have any protrusions.

10. 2. The image forming apparatus according to claim 1, wherein the roller cover is located at a downstream end of the drum unit in a mounting direction of the drum unit mounted in the housing.

11. 2. The image forming apparatus according to claim 1, wherein the roller cover has a central portion located upstream of both ends in the first direction in the mounting direction of the drum unit mounted in the housing.

Images