Image forming device

Abstract

To provide an image forming apparatus that can increase the degree of freedom in the arrangement of components on a frame of an apparatus main body.SOLUTION: An image forming apparatus 1 comprises: an apparatus main body 2; and a process cartridge 50 that has a photoconductor drum 51 and a cartridge frame 55 and is removably attached to the apparatus main body 2. The apparatus main body 2 includes a support frame 26 that supports one end of the process cartridge 50 and a left main body frame 25 that supports the other end. The cartridge frame 55 has a projecting rib 551 that projects toward the support frame 26, a first bearing part 511 that supports one end of the photoconductor drum 51, and a second bearing part 512 that supports the other end. The support frame 26 has a first guide rail 260A that guides the projecting rib 551. The left main body frame 25 has a second guide rail 250A that guides the second bearing part 512. The dimension Wa in a width direction of the first guide rail 260A is smaller than the dimension Wb in a width direction of the second guide rail 250A.SELECTED DRAWING: Figure 8

Description

[Technical field]

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

[0002] Conventionally, there has been known an image forming apparatus that includes a process cartridge having a photosensitive drum and detachably attachable to an apparatus main body, a frame that supports one end of the process cartridge in the axial direction of the photosensitive drum, and a frame that supports the other end of the process cartridge in the axial direction.

[0003] In an image forming device configured in this manner, when the process cartridge is attached to the device main body, the bearing portion supporting one end of the photosensitive drum in the axial direction is guided by a guide rail formed on a frame supporting one end of the process cartridge, and the drum shaft protruding from the other end of the photosensitive drum in the axial direction is guided by a guide rail formed on a frame supporting the other end of the process cartridge (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-162904 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, when the bearing portion and the drum shaft of the photosensitive drum are guided by the guide rail of the frame, the size of the guide rail in the width direction, which intersects both the mounting and dismounting direction of the process cartridge and the axial direction, tends to be large. When the size of the guide rail in the width direction is large, the space that the guide rail occupies in the frame increases, and the degree of freedom in arranging parts in the frame decreases.

[0006] Therefore, the present invention provides an image forming apparatus that reduces the space occupied in the frame by the guide rails that guide the process cartridge mounted in the apparatus main body, thereby increasing the freedom of arrangement of parts in the frame. [Means for solving the problem]

[0007] The image forming apparatus that solves the above problem has the following features.

[0008] That is, the image forming apparatus includes a device main body, a photosensitive drum, and a process cartridge having a cartridge frame supporting the photosensitive drum and detachable from the device main body, the device main body includes a first frame supporting one end of the process cartridge in an axial direction of the photosensitive drum, and a second frame supporting the other end of the process cartridge in the axial direction, the cartridge frame including a protruding rib protruding toward the first frame, a first bearing portion supporting one end of the photosensitive drum in the axial direction, and a second frame supporting the other end of the photosensitive drum in the axial direction. and a second bearing portion supporting a protruding rib, the first frame having a first guide rail that guides the protruding rib by sliding against the protruding rib when the process cartridge is mounted to the apparatus body, and the second frame having a second guide rail that guides the second bearing portion by sliding against the second bearing portion when the process cartridge is mounted to the apparatus body, and a size of the first guide rail in a width direction perpendicular to both the mounting / removal direction of the process cartridge and the axial direction is smaller than a size of the second guide rail in the width direction.

[0009] In this way, since the first guide rail guides the protruding rib of the cartridge frame, rather than the first bearing portion that supports one end of the photosensitive drum, the width dimension of the first guide rail can be reduced, which reduces the space that the first guide rail occupies in the first frame, and increases the degree of freedom in arranging components in the first frame.

[0010] The process cartridge further includes a protruding member that protrudes toward the first frame, and the first frame includes a retraction rail with which the protruding member does not interfere when the process cartridge is attached to the apparatus main body.

[0011] As a result, even if the process cartridge has a protruding member, the protruding member can be retracted by the retraction rail, thereby preventing the mounting operation of the process cartridge from being hindered.

[0012] Further, the process cartridge has a developing roller supported by the cartridge frame and movable between an abutment position where it abuts the photosensitive drum and a separation position where it is spaced apart from the photosensitive drum, the protruding member is supported by the cartridge frame, has a protruding amount toward the first frame greater than the protruding rib, and includes an arm for moving the developing roller between the abutment position and the separation position, the first frame has a first side surface facing the process cartridge in the axial direction, the first guide rail has a first guide surface located outside the first side surface in the axial direction, and the retraction rail has a first retraction surface located outside the first side surface and also outside the first guide surface in the axial direction and does not interfere with the arm when the process cartridge is attached to the apparatus main body.

[0013] This prevents the arm from interfering with the first frame, and prevents the mounting operation of the process cartridge from being hindered.

[0014] Further, the apparatus main body is provided with a lock lever supported by the first frame and pressing and fixing the photosensitive drum when the process cartridge is attached to the apparatus main body, the protruding member is formed on the first bearing portion, has the same amount of protrusion toward the first frame as the protruding rib, and includes a lever abutment portion with which the lock lever abuts, the first frame has a first side surface facing the process cartridge in the axial direction, the first guide rail has a first guide surface located outwardly of the first side surface in the axial direction, and the retraction rail has a second retraction surface located outwardly of the first side surface in the axial direction and at the same position as the first guide surface, and with which the lever abutment portion does not interfere when the process cartridge is attached to the apparatus main body.

[0015] This prevents interference between the lever contact portion and the first frame, making it possible to prevent hindrance to the mounting operation of the process cartridge.

[0016] Further, the process cartridge is supported by the cartridge frame and has a charger that charges the photosensitive drum, the protruding member is supported by the cartridge frame, has a smaller protruding amount toward the first frame than the protruding rib, and includes an electrode for supplying power to the charger, the first frame has a first side surface that faces the process cartridge in the axial direction, the first guide rail has a first guide surface that is positioned outer than the first side surface in the axial direction, and the retraction rail has a third retraction surface that is positioned outer than the first side surface and inner than the first guide surface in the axial direction and does not interfere with the electrode when the process cartridge is attached to the apparatus main body.

[0017] This prevents the electrodes from interfering with the first frame, and prevents the mounting operation of the process cartridge from being hindered.

[0018] Further, the apparatus main body includes a lock lever supported by the first frame and configured to press and fix the photosensitive drum when the process cartridge is mounted in the apparatus main body, the process cartridge includes a developing roller supported by the cartridge frame and movable between a contact position where it contacts the photosensitive drum and a spaced position where it is spaced from the photosensitive drum, and a charger supported by the cartridge frame and configured to charge the photosensitive drum, the protruding member includes an arm supported by the cartridge frame and having an amount of protrusion toward the first frame greater than that of the protruding rib, for moving the developing roller between the contact position and the spaced position, a lever abutment portion formed in the first bearing portion, having an amount of protrusion toward the first frame the same as that of the protruding rib, and with which the lock lever abuts, and an electrode supported by the cartridge frame and having an amount of protrusion toward the first frame smaller than that of the protruding rib, for supplying power to the charger, and the retraction rail includes a first retraction surface that is located outside the first side surface and outside the first guide surface in the axial direction and does not interfere with the arm when the process cartridge is attached to the apparatus body; a second retraction surface that is located outside the first side surface and at the same position as the first guide surface in the axial direction and does not interfere with the lever abutment portion when the process cartridge is attached to the apparatus body; and a third retraction surface that is located outside the first side surface and inside the first guide surface in the axial direction and does not interfere with the electrode when the process cartridge is attached to the apparatus body, wherein a difference in axial position between the first retraction surface and the first guide surface is the same as or larger than a difference in the amount of protrusion between the arm and the protruding rib toward the first frame, and a difference in axial position between the third retraction surface and the first guide surface is the same as or smaller than a difference in the amount of protrusion between the electrode and the protruding rib toward the first frame.

[0019] This makes it possible to suppress interference between the arm, the lever contact portion, and the electrode and the first frame, while increasing the degree of freedom in arranging components on the first frame.

[0020] In addition, the mounting direction of the process cartridge into the apparatus main body is inclined with respect to the vertical direction in a direction such that the upstream side in the mounting direction of the process cartridge is located on one side of the horizontal direction perpendicular to the axial direction relative to the downstream side, and the first guide rail is positioned on one side of the horizontal direction perpendicular to the axial direction relative to the retraction rail.

[0021] This improves the visibility of the first guide rail from the user when the user mounts the process cartridge into the apparatus main body, thereby improving the ease of mounting the process cartridge.

[0022] Further, the apparatus main body has a boss supported by the first frame, which protrudes through the first retraction surface in the axial direction towards the process cartridge and is movable between a pressing position where it presses the arm and a retracted position where it is away from the arm, and the first guide rail has a step surface formed between the first guide surface and the first side surface in the width direction, and the step surface has a regulating portion that abuts against the protruding rib and thereby regulates the trajectory of the arm when the process cartridge is attached to the apparatus main body to a position where the arm does not interfere with the boss in the retracted position.

[0023] This makes it possible to restrict the trajectory of the arm when the process cartridge is mounted in the apparatus main body to a position where the arm and the boss do not interfere with each other, thereby making it possible to prevent the boss from moving unexpectedly.

[0024] The apparatus main body further includes a top cover that covers an upper surface of the apparatus main body, and an exposure unit that is supported by the top cover and exposes the photosensitive drum, the first frame having a first side surface that faces the process cartridge in the axial direction, the first guide rail having a first guide surface that is located outboard of the first side surface in the axial direction, a first step surface that is formed between one end of the first guide surface in the width direction and the first side surface, and a second step surface that is formed between the other end of the first guide surface in the width direction and the first side surface, the first step surface having a first positioning portion that abuts against the exposure unit to restrict movement of the exposure unit to one side in a horizontal direction perpendicular to the axial direction, and the second step surface having a second positioning portion that abuts against the exposure unit to restrict movement of the exposure unit to the other side in a horizontal direction perpendicular to the axial direction.

[0025] With this, by sandwiching the exposure unit between the first positioning portion and the second positioning portion, the positioning of the exposure head can be performed.

[0026] Further, the first frame has a first side surface facing the process cartridge in the axial direction, and the first guide rail has a first guide surface located outside the first side surface in the axial direction, a first step surface formed between one end of the first guide surface in the width direction and the first side surface, and a second step surface formed between the other end of the first guide surface in the width direction and the first side surface, the first step surface having a third positioning portion that abuts against the protruding rib to restrict movement of the process cartridge to one side in the width direction, and the second step surface having a fourth positioning portion that abuts against the protruding rib to restrict movement of the process cartridge to the other side in the width direction.

[0027] With this, by sandwiching the protruding rib between the third positioning portion and the fourth positioning portion, it is possible to position the process cartridge mounted in the main body of the apparatus.

[0028] The apparatus main body further includes a top cover that covers an upper surface of the apparatus main body, and an exposure unit that is supported by the top cover and exposes the photosensitive drum, the first frame having a first side surface that faces the process cartridge in the axial direction, the first guide rail having a first guide surface located outside the first side surface in the axial direction, a first step surface formed between one end of the first guide surface in the width direction and the first side surface, and a second step surface formed between the other end of the first guide surface in the width direction and the first side surface, and the first step surface abuts against the exposure unit to thereby form a step surface in a horizontal direction perpendicular to the axial direction of the exposure unit. The second step surface has a first positioning portion that restricts movement to one side, and a third positioning portion that abuts against the protruding rib to restrict movement of the process cartridge to one side in the width direction, and the second step surface has a second positioning portion that abuts against the exposure device to restrict movement to the other side in a horizontal direction perpendicular to the axial direction of the exposure device, and a fourth positioning portion that abuts against the protruding rib to restrict movement of the process cartridge to the other side in the width direction, and the third positioning portion and the fourth positioning portion are located downstream of the first positioning portion and the second positioning portion in the mounting direction of the process cartridge to the apparatus body.

[0029] This makes it possible to improve the positional accuracy of the photosensitive drum when the process cartridge is mounted in the main body of the apparatus.

[0030] The first frame also has a first side surface that faces the process cartridge in the axial direction, and a positioning portion that is located inwardly of the first side surface in the axial direction and abuts against the first bearing portion when the process cartridge is attached to the apparatus main body to position the photosensitive drum.

[0031] As a result, even if a configuration is adopted in which the protruding rib of the process cartridge is guided by the first guide rail when the process cartridge is mounted in the apparatus main body, the positional accuracy of the photosensitive drum can be maintained.

[0032] Furthermore, the process cartridge can be mounted in the apparatus main body from above, and the protruding rib is located at the lower end of the cartridge frame when the process cartridge is in a position for being mounted in the apparatus main body.

[0033] As a result, the protruding rib can be guided by the first guide rail from the start of mounting the process cartridge to the apparatus body, making it easier to mount the process cartridge to the apparatus body.

[0034] Furthermore, the process cartridge can be mounted in the apparatus main body from above, and when the process cartridge is in a position for mounting in the apparatus main body, a portion of the protruding rib overlaps with the photosensitive drum when viewed in the horizontal direction.

[0035] As a result, the protruding rib can be guided by the first guide rail from the start of mounting the process cartridge to the apparatus body, making it easier to mount the process cartridge to the apparatus body. Effect of the Invention

[0036] According to the present invention, it is possible to increase the degree of freedom in arranging components on the first frame. [Brief description of the drawings]

[0037] [Figure 1] FIG. 2 is a central cross-sectional view showing the image forming apparatus. [Diagram 2] FIG. 2 is a perspective view showing the inside of the device main body. [Diagram 3] 2 is a perspective view of the process cartridge as viewed from the right front side. FIG. [Figure 4] 2 is a perspective view of the process cartridge as viewed from the left front side. FIG. [Diagram 5] FIG. 4A is a right side view showing the process cartridge, and FIG. 4B is a left side view showing the process cartridge. [Figure 6] FIG. 4 is a plan view showing the right end portion of the process cartridge. [Figure 7] FIG. 2 is a perspective view showing an exposure head. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. 4 is a perspective view showing the left side surface of the support frame. [Figure 11] 13 is a left side view showing the relationship between the protruding rib and protruding member of the process cartridge, the positioning portion of the exposure head, and each portion of the support frame. FIG. [Figure 12] FIG. 4 is a right side view showing the left main body frame. [Figure 13] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0039] [Image forming device] An image forming apparatus 1 shown in FIG. 1 is one embodiment of the image forming apparatus according to the present invention, and is a color laser printer that forms a multi-color image on paper S by electrophotography.

[0040] In the following description, the right side in Fig. 1 is defined as the front side of the image forming apparatus 1, the left side in Fig. 1 is defined as the rear side of the image forming apparatus 1, the front side of the paper in Fig. 1 is defined as the left side of the image forming apparatus 1, and the back side of the paper in Fig. 1 is defined as the right side of the image forming apparatus 1. In addition, the upper and lower sides in Fig. 1 are defined as the upper and lower sides of the image forming apparatus 1, respectively.

[0041] The image forming device 1 comprises a device main body 2, a paper feed section 3 having a paper feed tray 10 that supports paper S and a paper transport section 30 that transports paper S, and an image forming section 5 that forms an image on the paper S transported by the paper feed section 3.

[0042] The device body 2 is formed in a substantially rectangular parallelepiped shape and houses the paper feed unit 3 and the image forming unit 5. An opening 2A is formed on the top surface of the device body 2, and the device body 2 has a top cover 23 that covers the opening 2A in an openable and closable manner.

[0043] The top cover 23 is configured to be rotatable about a rotation shaft 23a at the rear end, and by rotating about the rotation shaft 23a, the top cover 23 can move between a closed position where the opening 2A is closed and an open position where the opening 2A is opened. The top cover 23 of the device body 2 is formed with a paper discharge tray 23b that is inclined downward from the front side to the rear side.

[0044] The paper feed unit 3 is disposed at the bottom of the device body 2, and transports paper S supported in a paper feed tray 10 to the image forming unit 5 by a paper transport unit 30. The paper feed tray 10 is configured to be slidable in the front-rear direction, and is configured to be movable between a storage position where it is stored in the device body 2, and a separation position where it is pulled out forward from the storage position.

[0045] The paper transport section 30 includes a paper feed roller 32, a separation roller 33, a separation pad 33a, a transport roller pair 34, and a registration roller pair 35. Within the device body 2, a transport path P for the paper S is configured, which runs from the paper feed tray 10 through the image forming section 5 to the paper discharge tray 23a.

[0046] The sheets S supported by the paper feed tray 10 are separated one by one by the paper feed roller 32, the separation roller 33, and the separation pad 33a, and sent out to the transport path P. The paper feed roller 32 is a roller that transports the sheets S from the paper feed tray 10 toward the image forming unit 5. The separation roller 33 and the separation pad 33a constitute a separation means that separates the sheets S supported by the paper feed tray 10 one by one.

[0047] The paper S sent to the transport path P is transported toward the image forming unit 5 by a transport roller pair 34 and a registration roller pair 35. The registration roller pair 35 regulates the movement of the leading edge of the transported paper S, temporarily stops the paper S, and then transports the paper S toward the image forming unit 5 at a predetermined timing.

[0048] The image forming unit 5 is disposed above the paper feeding unit 3, and includes four process cartridges 50 arranged side by side in the front-rear direction. Each process cartridge 50 is provided corresponding to each of the colors black, yellow, magenta, and cyan. The process cartridges 50 are detachably mounted in the apparatus main body 2. Each process cartridge 50 includes a photosensitive drum 51, a developing roller 52, a supply roller 53, and a charger 54.

[0049] The process cartridge 50 is mounted in the apparatus main body 2 with the axis X (see FIG. 3) of the photosensitive drum 51 aligned in the left-right direction. The left-right direction is an example of the axial direction. The developing roller 52 is configured to be movable between a contact position where it contacts the photosensitive drum 51 and a spaced position where it is spaced from the photosensitive drum 51. The supply roller 53 supplies the toner contained in the process cartridge 50 to the developing roller 52. The charger 54 charges the photosensitive drum 51.

[0050] The device main body 2 has an exposure head 59 for exposing the surface of the photosensitive drum 51. The exposure head 59 is an example of an exposure device. The exposure head 59 is supported by the top cover 23. Four exposure heads 59 are provided corresponding to the photosensitive drums 51, and the exposure heads 59 are arranged side by side in the front-rear direction.

[0051] The exposure head 59 has a main body 59a extending downward from the top cover 23, and an exposure unit 59b arranged at the lower end of the main body 59a. The exposure unit 59b is arranged close to and above the photosensitive drum 52 when the top cover 23 is closed. The exposure unit 59b is composed of an LED array having a plurality of LED elements arranged in parallel in the left-right direction.

[0052] A transfer belt 41 is disposed below the photosensitive drum 51, facing the photosensitive drum 51 across the transport path P. The transfer belt 41 is stretched between a drive roller 42 and a driven roller 43 disposed in front of the drive roller 42. The transfer belt 41, the drive roller 42, and the driven roller 43 form a belt device 40. A transfer roller 44 is disposed at a position facing each photosensitive drum 51 across the transfer belt 41.

[0053] In the image forming unit 5, the photosensitive drums 51, which are uniformly charged by the chargers 54, are selectively exposed to light by the exposure heads 59. By this exposure, charges are selectively removed from the surfaces of the photosensitive drums 51, and electrostatic latent images are formed on the surfaces of the photosensitive drums 51.

[0054] The toner contained in the process cartridge 50 is positively charged between the supply roller 53 and the developing roller 52, and is carried on the surface of the developing roller 52. A developing bias is applied to the developing roller 52, and when the electrostatic latent image formed on the photosensitive drum 51 faces the developing roller 52, toner is supplied from the developing roller 52 to the electrostatic latent image due to the potential difference between the electrostatic latent image and the developing roller 52. As a result, a toner image is formed on the surface of the photosensitive drum 51.

[0055] When the paper S transported toward the image forming unit 5 reaches the transfer belt 41, it is transported by the transfer belt 41 and passes sequentially between the transfer belt 41 and each photosensitive drum 51. Then, the toner image on the surface of the photosensitive drum 51 is transferred onto the paper S by a transfer bias applied to the transfer roller 44 when it faces the paper S.

[0056] In this embodiment, the transfer belt 41 is configured as a conveying belt that conveys the paper S onto which the toner image is transferred, but it is also possible to configure it as an intermediate transfer belt in which the toner image is transferred to the belt itself and the toner image transferred to the belt is further transferred to the paper S.

[0057] The paper S onto which the toner image has been transferred is transported to a fixing device 60. The fixing device 60 includes a heating roller 61 and a pressure roller 62 that is in pressure contact with the heating roller 61. The toner image on the paper S transported to the fixing device 60 is thermally fixed while the paper S passes between the heating roller 61 and the pressure roller 62.

[0058] The paper S on which the toner image has been thermally fixed is transported downstream in the transport direction from the fixing device 60, and further transported by a pair of intermediate paper discharge rollers 63 and a pair of paper discharge rollers 64 arranged downstream in the transport direction of the pair of intermediate paper discharge rollers 63, and discharged to the paper discharge tray 23b.

[0059] As shown in Fig. 2, the device body 2 includes a right body frame 24 and a left body frame 25 that are spaced apart from each other in the left-right direction. The right body frame 24 is located at the right end of the device body 2 and extends in the front-rear and up-down directions. The left body frame 25 is located at the left end of the device body 2 and extends in the front-rear and up-down directions. A support frame 26 is attached to the inner left and right surfaces of the right body frame 24 that face the left body frame 25. The support frame 26 is an example of a first frame, and the left body frame 25 is an example of a second frame.

[0060] The process cartridge 50 is disposed between the support frame 26 and the left main body frame 25, and is detachably supported by the support frame 26 and the left main body frame 25. The support frame 26 is located to the right of the process cartridge 50, and supports the right end of the process cartridge 50. The left main body frame 25 is located to the left of the process cartridge 50, and supports the left end of the process cartridge 50. The right end is an example of one end in the axial direction, and the left end is an example of the other end in the axial direction.

[0061] [Process cartridge] As shown in FIGS. 3 to 6, the process cartridge 50 has a cartridge frame 55 that supports the photosensitive drum 51 and the developing roller 52.

[0062] The cartridge frame 55 has, at its right end, a protruding rib 551 that protrudes toward the support frame 26, and a first bearing portion 511 that supports one end of the photosensitive drum 51 in the direction of the axis X. The cartridge frame 55 has, at its left end, a second bearing portion 512 that supports the other end of the photosensitive drum 51 in the direction of the axis X. The protruding rib 551 can be molded integrally with the cartridge frame 55, for example.

[0063] The cartridge frame 55 is provided, at its right end, with an arm 552 that protrudes toward the support frame 26, a lever contact portion 553, and an electrode 554. The arm 552, the lever contact portion 553, and the electrode 554 are examples of a protruding member.

[0064] The arm 552 is a member for moving the developing roller 52 between the contact position and the separated position, and when no pressing force is applied to the arm 552, the developing roller 52 moves to the contact position, and when pressed from above, the developing roller 52 moves to the separated position. The arm 552 is supported by the cartridge frame 55.

[0065] The arm 552 is formed so that the amount of protrusion toward the support frame 26 is greater than that of the protruding rib 551. The difference in the amount of protrusion toward the support frame 26 between the arm 552 and the protruding rib 551 is D1.

[0066] The apparatus main body 2 is provided with a boss 71 capable of pressing the arm 552 (see FIGS. 10 and 11). The boss 71 is movable between a pressing position where it presses the arm 552 of the process cartridge 50 and a retracted position where it is separated from the arm 552.

[0067] When the boss 71 moves to the pressing position, the boss 71 presses the arm 552, and the developing roller 52 moves to the separated position. When the boss 71 moves to the retracted position, the boss 71 moves away from the arm 552, and the developing roller 52 moves to the contact position. In other words, the boss 71 moves the developing roller 52 between the contact position and the separated position.

[0068] The apparatus main body 2 is provided with a lock lever 72 (see FIGS. 10 and 11) that presses and fixes the photosensitive drum 51 when the process cartridge 50 is attached to the apparatus main body 2, and the lever abutment portion 553 is a portion with which the lock lever 72 abuts. The lock lever 72 is supported by the support frame 26. The lever abutment portion 553 is formed on the first bearing portion 511. The lever abutment portion 553 protrudes toward the support frame 26 by the same amount as the protruding rib 551.

[0069] The electrode 554 is an electrode for supplying power to the charger 54, and the charger 54 and the electrode 554 are supported by the cartridge frame 55. The electrode 554 is formed so that the amount of protrusion toward the support frame 26 is smaller than that of the protruding rib 551. The difference in the amount of protrusion toward the support frame 26 between the electrode 554 and the protruding rib 551 is D2.

[0070] [Exposure head] 7, the exposure head 59 has a positioning portion 59c at the right end of the main body 59a. In the image forming apparatus 1, the positioning portion 59c abuts against the support frame 27, thereby restricting movement of the exposure head 59 in the front-rear direction. The front-rear direction is an example of a horizontal direction perpendicular to the axis X direction.

[0071] [Support frame] 8 to 11, the support frame 26 has an inner side surface 26A facing the process cartridge 50 in the direction of the axis X, and an outer side surface 26B opposite the inner side surface 26A facing the right main body frame 24 in the direction of the drum axis X. The inner side surface 26A is an example of a first side surface.

[0072] The support frame 26 has a first guide rail 260A and a retraction rail 260B. The first guide rail 260A and the retraction rail 260B are formed on the inner surface 26A side of the support frame 26. The first guide rail 260A and the retraction rail 260B are formed at four locations along the front-rear direction corresponding to the number of process cartridges 50 supported by the support frame 26.

[0073] When the process cartridge 50 is attached to the apparatus main body 2, the first guide rail 260A comes into sliding contact with the protruding rib 551 of the process cartridge 50 to guide the protruding rib 551. The first guide rail 260A has a dimension Wa in a width direction perpendicular to both the attachment / detachment direction of the process cartridge 50 and the direction of the axis X.

[0074] The first guide rail 260A has a first guide surface 261a, a first step surface 261b, and a second step surface 261c. The first guide surface 261a is located on the right side of the inner surface 26A, that is, on the outer side of the inner surface 26A in the direction of the axis X.

[0075] The first step surface 261b is a step surface formed between one end of the first guide surface 261a in the width direction of the first guide rail 260A and the inner side surface 26A. The second step surface 261c is a step surface formed between the other end of the first guide surface 261a in the width direction of the first guide rail 260A and the inner side surface 26A.

[0076] The first step surface 261b and the second step surface 261c are step surfaces formed between the first guide surface 261a and the inner side surface 26A in the width direction of the first guide rail 260A. The first step surface 261b is located forward of the second step surface 261c.

[0077] The first guide rail 260A has a first guide surface 261a, a first step surface 261b, and a second step surface 261c, which form a groove shape recessed outward in the direction of the axis X from the inner surface 26A.

[0078] At least a part of the first guide surface 261a is disposed at a position overlapping with the trajectory of the protruding rib 551 when the process cartridge 50 is mounted to the apparatus body 2, as viewed from the axis X direction, and is capable of sliding contact with the protruding rib 551 when the process cartridge 50 is mounted to the apparatus body 2. The first guide surface 261 guides the protruding rib 551 by sliding contact with it. The protruding rib 551 is guided by the first guide surface 261a, whereby the process cartridge 50 mounted to the apparatus body 2 is positioned in the left-right direction.

[0079] The retraction rail 260B is formed in a groove shape recessed outward in the direction of the axis X from the inner surface 26A, and is formed so as not to interfere with protruding members such as the arm 552, the lever abutment portion 553, and the electrode 554 when the process cartridge 50 is attached to the apparatus main body 2. The retraction rail 260B has a first retraction surface 262, a second retraction surface 263, and a third retraction surface 264.

[0080] The first retraction surface 262 is located to the right of the inner side surface 26A, that is, outside the inner side surface 26A in the direction of the axis X. The first retraction surface 262 is located to the right of the first guide surface 261a, that is, outside the first guide surface 261a in the direction of the axis X. The difference in position between the first retraction surface 262 and the first guide surface 261a in the direction of the axis X is W1. The difference in position W1 is the same as the difference in the protrusion amounts D1 or is larger than the difference in the protrusion amounts D1 (W1≧D1).

[0081] At least a part of the first retraction surface 262 is disposed at a position overlapping the trajectory of the arm 552 when the process cartridge 50 is attached to the apparatus main body 2, as viewed from the axis X direction. In addition, the amount of protrusion of the arm 552 toward the support frame 26 is larger than that of the protruding rib 551 by a difference in protrusion amount D1.

[0082] However, since the first retraction surface 262 is located to the right of the first guide surface 261a by the position difference W1, when the protruding rib 551 of the process cartridge 50 to be mounted in the apparatus main body 2 is guided by the first guide surface 261a, the first retraction surface 262 and the arm 552 slide against or are separated from each other in the direction of the axis X. In other words, the first retraction surface 262 is located at a position retracted from the arm 552 in the direction of the axis X and does not interfere with the arm 552 when the process cartridge 50 is mounted in the apparatus main body 2, so that the mounting operation of the process cartridge 50 can be prevented from being hindered.

[0083] The second retreat surface 263 is located to the right of the inner side surface 26A, that is, outward of the inner side surface 26A in the direction of the axis X. The second retreat surface 263 is in the same position as the first guide surface 261a in the direction of the axis X.

[0084] At least a part of the second retraction surface 263 is disposed at a position overlapping a trajectory of the lever abutment portion 553 when the process cartridge 50 is attached to the apparatus main body 2, as viewed from the direction of the axis X. In addition, the amount of protrusion of the lever abutment portion 553 toward the support frame 26 is the same as that of the protruding rib 551, and the second retraction surface 263 and the first guide surface 261a are at the same position in the direction of the axis X.

[0085] Therefore, in a state where the protruding rib 551 of the process cartridge 50 to be mounted in the apparatus body 2 is guided by the first guide surface 261a, the second retraction surface 263 and the lever abutment portion 553 come into sliding contact in the direction of the axis X. In other words, the second retraction surface 263 is at a position retracted from the lever abutment portion 553 in the direction of the axis X and does not interfere with the lever abutment portion 553 when the process cartridge 50 is mounted in the apparatus body 2, so that the mounting operation of the process cartridge 50 can be prevented from being hindered.

[0086] The third retreat surface 264 is located on the right side of the inner side surface 26A, that is, outside the inner side surface 26A in the direction of the axis X. The third retreat surface 264 is located on the left side of the first guide surface 261a, that is, inside the first guide surface 261a in the direction of the axis X. The difference in position between the third retreat surface 264 and the first guide surface 261a in the direction of the axis X is W2. The difference in position W2 is the same as the difference in the protrusion amount D2 or is smaller than the difference in the protrusion amount D2 (W2≦D2).

[0087] At least a part of the third retraction surface 264 is disposed at a position overlapping with a trajectory of the electrode 554 when the process cartridge 50 is attached to the apparatus main body 2, as viewed from the direction of the axis X. In addition, the third retraction surface 264 is located to the left of the first guide surface 261a by a position difference W2.

[0088] However, since the amount of protrusion of the electrode 554 toward the support frame 26 is smaller than that of the protruding rib 551 by the difference in protrusion amount D2, when the protruding rib 551 of the process cartridge 50 mounted in the apparatus body 2 is guided by the first guide surface 261a, the third retraction surface 264 and the electrode 554 slide against each other or are separated from each other in the direction of the axis X. In other words, the third retraction surface 264 is at a position retracted from the arm 552 in the direction of the axis X and does not interfere with the electrode 554 when the process cartridge 50 is mounted in the apparatus body 2, so that the mounting operation of the process cartridge 50 can be prevented from being hindered.

[0089] The support frame 26 has a positioning portion 265 on the inner surface 26A side that abuts against a first bearing portion 511 supporting one end of the photosensitive drum 51 when the process cartridge 50 is attached to the apparatus main body 2, thereby positioning the photosensitive drum 51. The positioning portion 265 is located on the left side of the inner surface 26A, that is, on the inside of the inner surface 26A in the direction of the axis X. The positioning portion 265 is configured to support the first bearing portion 511 of the process cartridge 50 attached to the apparatus main body 2 from below.

[0090] With the first bearing portion 511 supported by the positioning portion 265, the lock lever 72 abuts against a lever abutment portion 553 of the first bearing portion 511 from above, whereby the photosensitive drum 51 is fixed in a positioned state.

[0091] In this way, by positioning the photosensitive drum 50 using the positioning portion 265 formed on the support frame 26, it is possible to maintain the positional accuracy of the photosensitive drum 51 even when the protruding rib 551 of the process cartridge 50 is guided by the first guide rail 260A when the process cartridge 50 is attached to the apparatus main body 2.

[0092] The support frame 26 has through holes 266 formed in an arc shape penetrating the support frame 26 in the left-right direction. The through holes 266 are formed mainly in the first retraction surface 262 of the support frame 26. The positioning portions 265 and the through holes 266 are formed at four locations along the front-rear direction corresponding to the number of process cartridges 50 supported by the support frame 26.

[0093] The first guide rail 260A has a restricting portion 267, a first positioning portion 268a, a second positioning portion 268b, a third positioning portion 269a, and a fourth positioning portion 269b.

[0094] The restricting portion 267 is formed on the first step surface 261b of the first guide rail 260A. The restricting portion 267 is capable of restricting the forward movement of the process cartridge 50 by coming into contact with the protruding rib 551 of the process cartridge 50 which is attached to or detached from the apparatus main body 2.

[0095] The first positioning portion 268a is formed on the first step surface 261b of the first guide rail 260A. The first positioning portion 268a abuts against a front surface of a positioning portion 59c of the exposure head 59 extending downward from the top cover 23 in the closed position. The first positioning portion 268a abuts against the front surface of the positioning portion 59c, thereby making it possible to restrict forward movement of the exposure head 59. The front is an example of one side in the horizontal direction perpendicular to the axis X direction.

[0096] The second positioning portion 268b is formed on the second step surface 261c of the first guide rail 260A. The second positioning portion 268b abuts against the rear surface of the positioning portion 59c of the exposure head 59 extending downward from the top cover 23 in the closed position. The second positioning portion 268b abuts against the rear surface of the positioning portion 59c, thereby making it possible to restrict rearward movement of the exposure head 59. The rear is an example of the other side in the horizontal direction perpendicular to the axis X direction.

[0097] In this way, the first positioning portion 268a is abutted against the front surface of the positioning portion 59c and the second positioning portion 268b is abutted against the rear surface of the positioning portion 59c, and the positioning portion 59c is sandwiched between the first positioning portion 268a and the second positioning portion 268b, making it possible to position the exposure head 59 in the front-to-rear direction.

[0098] The third positioning portion 269a is formed on the first step surface 261b of the first guide rail 260A. The third positioning portion 269a abuts against the front surface of the protruding rib 551 of the process cartridge 50 mounted in the apparatus main body 2. By the third positioning portion 269a abutting against the front surface of the protruding rib 551, it is possible to restrict the movement of the process cartridge 50 mounted in the apparatus main body 2 to one side in the width direction of the first guide rail 260A.

[0099] The fourth positioning portion 269b is formed on the second step surface 261c of the first guide rail 260A. The fourth positioning portion 269b abuts against the rear surface of the protruding rib 551 of the process cartridge 50 mounted in the apparatus main body 2. The fourth positioning portion 269b abuts against the rear surface of the protruding rib 551, thereby making it possible to restrict movement of the process cartridge 50 mounted in the apparatus main body 2 to the other side in the width direction of the first guide rail 260A.

[0100] In this manner, by abutting the third positioning portion 269a against the front surface of the protruding rib 551 and abutting the fourth positioning portion 269b against the rear surface of the protruding rib 551, and sandwiching the protruding rib 551 between the third positioning portion 269a and the fourth positioning portion 269b, it is possible to position the process cartridge 50 attached to the apparatus main body 2 in the width direction of the first guide rail 260A.

[0101] Further, the third positioning portion 269a and the fourth positioning portion 269b are disposed downstream in the mounting direction of the process cartridge 50 relative to the apparatus main body 2 from the first positioning portion 268a and the second positioning portion 268b.

[0102] As a result, the third positioning portion 269a and the fourth positioning portion 269b, which position the process cartridge 50, are located near the photosensitive drum 51 in the mounting direction of the process cartridge 50 relative to the device main body 2, thereby improving the positional accuracy of the photosensitive drum 51 when the process cartridge 50 is mounted in the device main body 2.

[0103] [Left body frame] As shown in FIGS. 12 and 13, the left main body frame 25 has an inner surface 25A facing the process cartridge 50 in the direction of the axis X, and an outer surface 25B opposite to the inner surface 25A.

[0104] The left main body frame 25 has a second guide rail 250A. The second guide rail 250A is formed on the inner surface 25A side of the left main body frame 25. The second guide rail 250A is formed at four locations along the front-rear direction corresponding to the number of process cartridges 50 supported by the left main body frame 25.

[0105] When the process cartridge 50 is attached to the apparatus main body 2, the second guide rail 250A comes into sliding contact with the second bearing portion 512 of the photosensitive drum 51 in the process cartridge 50, thereby guiding the second bearing portion 512. The second guide rail 250A has a width dimension Wb that is perpendicular to both the attachment / detachment direction of the process cartridge 50 and the direction of the axis X. The width dimension Wa of the first guide rail 260A is smaller than the width dimension Wb of the second guide rail 250A.

[0106] The second guide rail 250A has a second guide surface 251. The second guide surface 251 is located on the left side of the inner side surface 25A, that is, on the outer side of the inner side surface 25A in the direction of the axis X. The second guide rail 250A has a groove shape in which the second guide surface 251 is recessed from the inner side surface 25A outward in the direction of the axis X.

[0107] At least a part of the second guide surface 251 is disposed at a position overlapping with a trajectory of the second bearing portion 512 when the process cartridge 50 is mounted to the apparatus body 2, as viewed from the axis X direction, and is capable of sliding contact with the second bearing portion 512 when the process cartridge 50 is mounted to the apparatus body 2. The second guide surface 251 guides the second bearing portion 512 by sliding contact with the second bearing portion 512. The second bearing portion 512 is guided by the second guide surface 251, whereby the process cartridge 50 is positioned in the left-right direction.

[0108] The second guide rail 250A has a positioning portion 252 against which the second bearing portion 512 of the photosensitive drum 51 abuts when the process cartridge 50 is attached to the apparatus body 2. The positioning portion 252 is formed on the inner surface 25A side of the left main body frame 25, and is located at the lower end of the second guide rail 250A. The positioning portion 252 supports the second bearing portion 512 of the process cartridge 50 attached to the apparatus body 2 from below, thereby positioning the photosensitive drum 51.

[0109] [Installing the process cartridge] When the process cartridge 50 is mounted in the apparatus main body 2 in the image forming apparatus 1, the process cartridge 50 is inserted into the apparatus main body 2 from above. The process cartridge 50 inserted into the apparatus main body 2 moves downward with the protruding rib 551 of the process cartridge 50 guided by the first guide rail 260A of the support frame 26 and the second bearing portion 512 of the process cartridge 50 guided by the second guide rail 250A of the left main body frame 25.

[0110] When the process cartridge 50 moves downward and the first bearing portion 511 of the photosensitive drum 51 abuts against the positioning portion 265 and the second bearing portion 512 abuts against the positioning portion 252, the photosensitive drum 51 is positioned relative to the device main body 2 and the process cartridge 50 is attached to the device main body 2.

[0111] In this case, the process cartridge 50 is positioned in the left-right direction by the protruding rib 551 being guided by the first guide rail 260A and the second bearing portion 512 being guided by the second guide rail 250A.

[0112] In this way, in the process cartridge 50, the first guide rail 260A guides the protruding rib 551 of the cartridge frame 55, rather than the first bearing portion 511 that supports one end of the photosensitive drum 50, so it is possible to reduce the width direction dimension Wa of the first guide rail 260A. This makes it possible to reduce the space occupied by the first guide rail 260A in the support frame 26, and thus increases the degree of freedom in arranging parts in the support frame 26.

[0113] Furthermore, in a state where the protruding rib 551 is guided by the first guide surface 261, the first retraction surface 262 of the retraction rail 260B corresponding to the arm 552 of the process cartridge 50 is in a position retracted from the arm 552, and the arm 552 does not interfere with the first retraction surface 262. In other words, the protruding amount of the arm 552 toward the support frame 26 is greater than that of the protruding rib 551 by the difference in protruding amount D1, but the first retraction surface 262 is located to the right of the first guide surface 261a by the position difference W1, so that the arm 552 does not interfere with the support frame 26, and thus it is possible to prevent the mounting operation of the process cartridge 50 from being hindered.

[0114] Furthermore, in a state where the protruding rib 551 is guided by the first guide surface 261, the second retraction surface 263 of the retraction rail 260B corresponding to the lever abutment portion 553 of the process cartridge 50 is in a position retracted from the lever abutment portion 553, and the lever abutment portion 553 does not interfere with the second retraction surface 263. In other words, the amount of protrusion of the lever abutment portion 553 toward the support frame 26 is the same as that of the protruding rib 551, and the second retraction surface 263 and the first guide surface 261a are in the same position in the direction of the axis X, so that the lever abutment portion 553 does not interfere with the support frame 26, and it is possible to suppress hindrance of the mounting operation of the process cartridge 50.

[0115] In addition, since the second retreat surface 263 and the first guide surface 261a are at the same position in the direction of the axis X, the space on the outer surface 26B side of the portion of the support frame 26 where the second retreat surface 263 is formed does not become excessively small. This makes it possible to prevent the degree of freedom of arrangement of components on the outer surface 26B side of the support frame 26 from being excessively restricted.

[0116] Furthermore, in a state where the protruding rib 551 is guided by the first guide surface 261, the third retraction surface 264 of the retraction rail 260B corresponding to the electrode 554 of the process cartridge 50 is in a position retracted from the electrode 554, and the electrode 554 does not interfere with the third retraction surface 264. In other words, the third retraction surface 264 is located to the left of the first guide surface 261a by a position difference W2, but the protruding amount of the electrode 554 toward the support frame 26 is smaller than the protruding rib 551 by a protruding amount difference D2, so that the electrode 554 does not interfere with the support frame 26, and thus it is possible to suppress hindrance of the mounting operation of the process cartridge 50.

[0117] In addition, by positioning the third retreat surface 264 to the left of the first guide surface 261a, it is possible to increase the space on the outer surface 26B side of the portion of the support frame 26 where the third retreat surface 264 is formed. This increases the degree of freedom in arranging components on the outer surface 26B side of the support frame 26.

[0118] In this way, in the image forming apparatus 1, even if the process cartridge 50 has protruding members such as the arm 552, the lever abutment portion 553, and the electrode 554, these are allowed to escape by the first retraction surface 262, the second retraction surface 263, and the third retraction surface 264 of the retraction rail 260B, respectively, thereby preventing the installation operation of the process cartridge 50 from being hindered.

[0119] In addition, in the image forming apparatus 1, even when removing the process cartridge 50 attached to the apparatus main body 2, the protruding rib 551 is guided by the first guide surface 261, thereby preventing interference between the arm 552, the lever abutment portion 553, and the electrode 554 and the first retraction surface 262, the second retraction surface 263, and the third retraction surface 264.

[0120] In addition, in the image forming apparatus 1, the amount of protrusion of the arm 552 toward the support frame 26 is greater than that of the protruding rib 551 by the difference in the amount of protrusion D1, the amount of protrusion of the lever abutment portion 553 toward the support frame 26 is the same as that of the protruding rib 551, and the amount of protrusion of the electrode 554 toward the support frame 26 is smaller than that of the protruding rib 551 by the difference in the amount of protrusion D2.

[0121] On the other hand, the first retreat surface 262 is located to the right of the first guide surface 261a by a position difference W1, the second retreat surface 263 is at the same position as the first guide surface 261a in the direction of the axis X, and the third retreat surface 264 is located to the left of the first guide surface 261a by a position difference W2.

[0122] In this way, the first guide surface 261, the first retraction surface 262, the second retraction surface 263, and the third retraction surface 264 are positioned in accordance with the amount of protrusion of the arm 552, the protruding rib 551, the lever abutment portion 553, and the electrode 554 toward the support frame 26, thereby making it possible to increase the freedom of arrangement of components on the support frame 26 while suppressing interference between the arm 552, the lever abutment portion 553, and the electrode 554 and the support frame 26.

[0123] Further, the boss 71 capable of pressing the arm 552 of the process cartridge 50 is supported on the outer surface 26B of the support frame 26. As shown in Fig. 10, the boss 71 protrudes leftward beyond the first retraction surface 262 through the through hole 266 from a position between the support frame 26 and the right main body frame 24 in the direction of the drum axis X. In other words, the boss 71 protrudes toward the process cartridge 50 side, penetrating the first retraction surface 262 in the direction of the axis X. The boss 71 moves between the pressing position and the retraction position along the arc shape of the through hole 266.

[0124] As shown in Figures 10 and 11, the retraction rail 260B has a step surface 270 between the first retraction surface 262 and the third retraction surface 264, and the boss 71 is configured to be located rearward of the step surface 270 (the position shown by the solid line in Figure 11) when in the pressing position, and to be located forward of the step surface 270 (the position shown by the dotted line in Figure 11) when in the retracted position, in the front-to-rear direction.

[0125] However, since the boss 71 is attached to the support frame 26 with some play in the movement direction, a part of the boss 71 may protrude rearward from the step surface 270 even when in the retracted position (see FIG. 8). If the process cartridge 50 is thus mounted to the apparatus main body with the boss 71 protruding rearward from the step surface 270, the arm 552 passing through the first retracted surface 262 in which the through hole 266 is formed may interfere with the boss 71, causing the arm 552 to move the boss 71 toward the pressing position.

[0126] Therefore, in the image forming apparatus 1, a regulating portion 267 is formed on the first step surface 261b of the first guide rail 260A, and when the process cartridge 50 is attached to the apparatus main body 2, the regulating portion 267 abuts against the protruding rib 551 of the process cartridge 50, thereby regulating the forward movement of the process cartridge 50.

[0127] Since the regulating portion 267 regulates the forward movement of the process cartridge 50, the trajectory of the arm 552 when the process cartridge 50 is mounted in the apparatus body 2 can be regulated to a position where the arm 552 and the boss 71 do not interfere with each other, and the boss 71 can be prevented from moving unexpectedly. If it is possible to regulate the trajectory of the arm 552 when the process cartridge 50 is mounted in the apparatus body 2 to a position where the arm 552 and the boss 71 do not interfere with each other, the regulating portion 267 can be formed on the second step surface 261c.

[0128] Furthermore, in the image forming apparatus 1, the process cartridge 50 can be attached to the apparatus main body 2 from above, and the protruding rib 551 is located at the lower end of the process cartridge 50 when the process cartridge 50 is in a posture for attachment to the apparatus main body 2 (the posture shown in FIG. 8). In particular, when the process cartridge 50 is in a posture for attachment to the apparatus main body 2, a part of the protruding rib 551 overlaps with the photosensitive drum 50 located at the lower end of the process cartridge 50 when viewed from the horizontal direction.

[0129] Therefore, from the start of mounting the process cartridge 50 into the apparatus main body 2, the protruding rib 551 can be guided by the first guide rail 260A, making it easy to mount the process cartridge 50 into the apparatus main body 2.

[0130] In the image forming apparatus 1, the mounting direction of the process cartridge 50 to the apparatus body 2 is inclined with respect to the vertical direction so that the upstream side in the mounting direction of the process cartridge 50 is located further forward in the horizontal direction perpendicular to the axis X direction than the downstream side, and the first guide rail 260A and the retraction rail 260B are generally inclined backward from the upper end side to the lower end side. In other words, the upper end of the first guide rail 260A is located forward of the lower end, and the upper end of the retraction rail 260B is located forward of the lower end.

[0131] The first guide rail 260A is disposed forward of the retreat rail 260B. The forward side is one side in the horizontal direction perpendicular to the X-axis direction.

[0132] In the image forming apparatus 1, when a user installs the process cartridge 50 in the device main body 2, the process cartridge 50 is inserted into the device main body 2 from the front side. However, by positioning the first guide rail 260A that guides the protruding rib 551 forward of the retraction rail 260B, the first guide rail 260A is more visible to the user, and the ease of installation of the process cartridge 50 can be improved. [Explanation of symbols]

[0133] 1. Image forming device 2. Device body 23 Top cover 24 Right body frame 25 Left body frame 25A inner surface 26 Support frame 26A Inner side 50 Process Cartridge 51 Photosensitive drum 52 Developing roller 54 Charger 55 Cartridge Frame 59 Exposure head 71 Boss 72 Lock lever 250A Second guide rail 251 Second guide surface 260A First guide rail 260B Evacuation rail 261a First guide surface 261b 1st step surface 261c 2nd step surface 262 First Retreat Surface 263 Second Retreat Plane 264 3rd Evacuation Plane 265 Positioning part 267 Regulatory Department 268a First positioning part 268b Second positioning part 269a Third positioning part 269b 4th positioning part 511 1st bearing part 512 2nd bearing part 551 Protruding rib 552 Arm 553 Lever contact part 554 Electrode D1 Difference in protrusion (between arm and protruding rib towards the support frame) D2 Difference in protrusion (between the electrode and the protruding rib towards the support frame) W1 (Axial direction position difference between the first retraction surface and the first guide surface) W2 (Axial direction position difference between the third retraction surface and the first guide surface) Wa (width of first guide rail) Wb (2nd guide rail width direction) dimension X axis

Claims

1. A device body, a process cartridge including a photosensitive drum and a cartridge frame supporting the photosensitive drum and detachably mountable to the main body of the apparatus; the apparatus main body includes a first frame supporting one end of the process cartridge in an axial direction of the photosensitive drum, and a second frame supporting the other end of the process cartridge in the axial direction, the cartridge frame has a protruding rib protruding toward the first frame, a first bearing portion supporting one end of the photosensitive drum in the axial direction, and a second bearing portion supporting the other end of the photosensitive drum in the axial direction, the first frame has a first guide rail that slides against the protruding rib when the process cartridge is mounted in the apparatus main body, and the second frame has a second guide rail that slides against the second bearing portion when the process cartridge is mounted in the apparatus main body, and guides the second bearing portion; a size of the first guide rail in a width direction perpendicular to both the mounting and demounting direction of the process cartridge and the axial direction is smaller than a size of the second guide rail in the width direction; the process cartridge is supported by the cartridge frame and includes a developing roller movable between a contact position where the developing roller contacts the photosensitive drum and a spaced position where the developing roller is spaced from the photosensitive drum, and a protruding member that protrudes toward the first frame; the first frame includes a first side surface facing the process cartridge in the axial direction, and a retraction rail with which the protruding member does not interfere when the process cartridge is mounted in the apparatus main body; the protruding member is supported by the cartridge frame, has a protruding amount toward the first frame greater than the protruding rib, and includes an arm for moving the developing roller between a contact position and a separation position, The first guide rail has a first guide surface located outwardly of the first side surface in the axial direction, An image forming apparatus in which the retraction rail is located outside the first side surface and outside the first guide surface in the axial direction, and has a first retraction surface that does not interfere with the arm when the process cartridge is attached to the apparatus main body.

2. A device body, a process cartridge including a photosensitive drum and a cartridge frame supporting the photosensitive drum and detachably mountable to the main body of the apparatus; the apparatus main body includes a first frame supporting one end of the process cartridge in an axial direction of the photosensitive drum, and a second frame supporting the other end of the process cartridge in the axial direction, the cartridge frame has a protruding rib protruding toward the first frame, a first bearing portion supporting one end of the photosensitive drum in the axial direction, and a second bearing portion supporting the other end of the photosensitive drum in the axial direction, the first frame has a first guide rail that slides against the protruding rib when the process cartridge is mounted in the apparatus main body, and the second frame has a second guide rail that slides against the second bearing portion when the process cartridge is mounted in the apparatus main body, and guides the second bearing portion; a size of the first guide rail in a width direction perpendicular to both the mounting and demounting direction of the process cartridge and the axial direction is smaller than a size of the second guide rail in the width direction; the process cartridge includes a protruding member protruding toward the first frame, the first frame includes a first side surface facing the process cartridge in the axial direction, and a retraction rail with which the protruding member does not interfere when the process cartridge is mounted in the apparatus main body; the apparatus main body includes a lock lever supported by the first frame and configured to press and fix the photosensitive drum when the process cartridge is mounted in the apparatus main body, the protruding member is formed in the first bearing portion, has a protruding amount toward the first frame equal to that of the protruding rib, and includes a lever abutment portion against which the lock lever abuts, The first guide rail has a first guide surface located outwardly of the first side surface in the axial direction, An image forming apparatus in which the retraction rail is located outside the first side surface in the axial direction and at the same position as the first guide surface, and has a second retraction surface with which the lever abutment portion does not interfere when the process cartridge is attached to the apparatus main body.

3. A device body, a process cartridge including a photosensitive drum and a cartridge frame supporting the photosensitive drum and detachably mountable to the main body of the apparatus; the apparatus main body includes a first frame supporting one end of the process cartridge in an axial direction of the photosensitive drum, and a second frame supporting the other end of the process cartridge in the axial direction, the cartridge frame has a protruding rib protruding toward the first frame, a first bearing portion supporting one end of the photosensitive drum in the axial direction, and a second bearing portion supporting the other end of the photosensitive drum in the axial direction, the first frame has a first guide rail that slides against the protruding rib when the process cartridge is mounted in the apparatus main body, and the second frame has a second guide rail that slides against the second bearing portion when the process cartridge is mounted in the apparatus main body, and guides the second bearing portion; a size of the first guide rail in a width direction perpendicular to both the mounting and demounting direction of the process cartridge and the axial direction is smaller than a size of the second guide rail in the width direction; the process cartridge is supported by the cartridge frame and includes a charger that charges the photosensitive drum and a protruding member that protrudes toward the first frame; the first frame includes a first side surface facing the process cartridge in the axial direction, and a retraction rail with which the protruding member does not interfere when the process cartridge is mounted in the apparatus main body; the protruding member is supported by the cartridge frame, has a protruding amount toward the first frame smaller than that of the protruding rib, and includes an electrode for supplying power to the charger, The first guide rail has a first guide surface located outwardly of the first side surface in the axial direction, An image forming apparatus in which the retraction rail is located outside the first side surface in the axial direction and inside the first guide surface, and has a third retraction surface that does not interfere with the electrode when the process cartridge is attached to the apparatus main body.

4. A device body, a process cartridge including a photosensitive drum and a cartridge frame supporting the photosensitive drum and detachably mountable to the main body of the apparatus; the apparatus main body includes a first frame supporting one end of the process cartridge in an axial direction of the photosensitive drum, and a second frame supporting the other end of the process cartridge in the axial direction, the cartridge frame has a protruding rib protruding toward the first frame, a first bearing portion supporting one end of the photosensitive drum in the axial direction, and a second bearing portion supporting the other end of the photosensitive drum in the axial direction, the first frame has a first guide rail that slides against the protruding rib when the process cartridge is mounted in the apparatus main body, and the second frame has a second guide rail that slides against the second bearing portion when the process cartridge is mounted in the apparatus main body, and guides the second bearing portion; a size of the first guide rail in a width direction perpendicular to both the mounting and demounting direction of the process cartridge and the axial direction is smaller than a size of the second guide rail in the width direction; the process cartridge includes a protruding member protruding toward the first frame, the first frame includes a retraction rail that is not interfered with by the protruding member when the process cartridge is mounted in the apparatus main body, a mounting direction of the process cartridge with respect to the main body of the apparatus is inclined with respect to a vertical direction in a direction in which an upstream side in the mounting direction of the process cartridge is located on one side in a horizontal direction perpendicular to the axial direction relative to a downstream side, The first guide rail is disposed on one side of the retraction rail in a horizontal direction perpendicular to the axial direction.

5. A device body, a process cartridge including a photosensitive drum and a cartridge frame supporting the photosensitive drum and detachably mountable to the main body of the apparatus; the apparatus main body includes a first frame supporting one end of the process cartridge in an axial direction of the photosensitive drum, and a second frame supporting the other end of the process cartridge in the axial direction, the cartridge frame has a protruding rib protruding toward the first frame, a first bearing portion supporting one end of the photosensitive drum in the axial direction, and a second bearing portion supporting the other end of the photosensitive drum in the axial direction, the first frame has a first guide rail that slides against the protruding rib when the process cartridge is mounted in the apparatus main body, and the second frame has a second guide rail that slides against the second bearing portion when the process cartridge is mounted in the apparatus main body, and guides the second bearing portion; a size of the first guide rail in a width direction perpendicular to both the mounting and demounting direction of the process cartridge and the axial direction is smaller than a size of the second guide rail in the width direction; the first frame has a first side surface facing the process cartridge in the axial direction, the first guide rail has a first guide surface located outboard of the first side surface in the axial direction, a first step surface formed between one end of the first guide surface in the width direction and the first side surface, and a second step surface formed between the other end of the first guide surface in the width direction and the first side surface, the first step surface has a third positioning portion that restricts movement of the process cartridge to one side in the width direction by contacting the protruding rib, The second step surface has a fourth positioning portion that restricts movement of the process cartridge to the other side in the width direction by contacting the protruding rib.

6. A device body, a process cartridge including a photosensitive drum and a cartridge frame supporting the photosensitive drum and detachably mountable to the main body of the apparatus; the apparatus main body includes a first frame supporting one end of the process cartridge in an axial direction of the photosensitive drum, and a second frame supporting the other end of the process cartridge in the axial direction, the cartridge frame has a protruding rib protruding toward the first frame, a first bearing portion supporting one end of the photosensitive drum in the axial direction, and a second bearing portion supporting the other end of the photosensitive drum in the axial direction, the first frame has a first guide rail that slides against the protruding rib when the process cartridge is mounted in the apparatus main body, and the second frame has a second guide rail that slides against the second bearing portion when the process cartridge is mounted in the apparatus main body, and guides the second bearing portion; a size of the first guide rail in a width direction perpendicular to both the mounting and demounting direction of the process cartridge and the axial direction is smaller than a size of the second guide rail in the width direction; An image forming apparatus, wherein the first frame has a first side surface facing the process cartridge in the axial direction, and a positioning portion located inward of the first side surface in the axial direction and abuts against the first bearing portion when the process cartridge is attached to an apparatus main body to position the photosensitive drum.

7. A device body, a process cartridge including a photosensitive drum and a cartridge frame supporting the photosensitive drum and detachably mountable to the main body of the apparatus; the apparatus main body includes a first frame supporting one end of the process cartridge in an axial direction of the photosensitive drum, and a second frame supporting the other end of the process cartridge in the axial direction, the cartridge frame has a protruding rib protruding toward the first frame, a first bearing portion supporting one end of the photosensitive drum in the axial direction, and a second bearing portion supporting the other end of the photosensitive drum in the axial direction, the first frame has a first guide rail that slides against the protruding rib when the process cartridge is mounted in the apparatus main body, and the second frame has a second guide rail that slides against the second bearing portion when the process cartridge is mounted in the apparatus main body, and guides the second bearing portion; a size of the first guide rail in a width direction perpendicular to both the mounting and demounting direction of the process cartridge and the axial direction is smaller than a size of the second guide rail in the width direction; the process cartridge is mountable from above into the main body of the apparatus, The protruding rib is located at a lower end of the cartridge frame when the process cartridge is in a position for being mounted in the main body of the image forming apparatus.

8. A device body, a process cartridge including a photosensitive drum and a cartridge frame supporting the photosensitive drum and detachably mountable to the main body of the apparatus; the apparatus main body includes a first frame supporting one end of the process cartridge in an axial direction of the photosensitive drum, and a second frame supporting the other end of the process cartridge in the axial direction, the cartridge frame has a protruding rib protruding toward the first frame, a first bearing portion supporting one end of the photosensitive drum in the axial direction, and a second bearing portion supporting the other end of the photosensitive drum in the axial direction, the first frame has a first guide rail that slides against the protruding rib when the process cartridge is mounted in the apparatus main body, and the second frame has a second guide rail that slides against the second bearing portion when the process cartridge is mounted in the apparatus main body, and guides the second bearing portion; a size of the first guide rail in a width direction perpendicular to both the mounting and demounting direction of the process cartridge and the axial direction is smaller than a size of the second guide rail in the width direction; the process cartridge is mountable from above into the main body of the apparatus, When the process cartridge is in a position for being mounted in the main body of the image forming apparatus, a part of the protruding rib overlaps with the photosensitive drum when viewed from the horizontal direction.

9. The device body includes: a lock lever supported by the first frame for pressing and fixing the photosensitive drum when the process cartridge is mounted in the main body of the apparatus; The process cartridge comprises: a developing roller supported by the cartridge frame and movable between a contact position where the developing roller contacts the photosensitive drum and a spaced position where the developing roller is spaced from the photosensitive drum; a charger supported by the cartridge frame and configured to charge the photosensitive drum; The protruding member is an arm supported by the cartridge frame, the arm having a larger protruding amount toward the first frame than the protruding rib, the arm being configured to move the developing roller between a contact position and a separation position; a lever contact portion that is formed in the first bearing portion, has the same protruding amount toward the first frame as the protruding rib, and is in contact with the lock lever; an electrode supported by the cartridge frame, the electrode having a protruding amount toward the first frame smaller than that of the protruding rib, the electrode being for supplying power to the charger; The evacuation rail is a first retraction surface that is located outside the first side surface and the first guide surface in the axial direction and does not interfere with the arm when the process cartridge is mounted to the apparatus main body; a second retraction surface that is located outside the first side surface in the axial direction and at the same position as the first guide surface, and that does not interfere with the lever abutment portion when the process cartridge is mounted to the apparatus main body; a third retraction surface that is located outside the first side surface and inside the first guide surface in the axial direction and does not interfere with the electrode when the process cartridge is mounted in the apparatus main body, a difference in the axial position between the first retraction surface and the first guide surface is equal to or greater than a difference in the amount of protrusion between the arm and the protruding rib toward the first frame, 2 . The image forming apparatus according to claim 1 , wherein a difference in axial position between the third retraction surface and the first guide surface is equal to or smaller than a difference in protrusion amount between the electrode and the protruding rib toward the first frame.

10. The device body includes: a boss supported by the first frame, penetrating the first retraction surface in the axial direction and protruding toward the process cartridge, the boss being movable between a pressing position where the arm is pressed and a retraction position where the boss is separated from the arm, the first guide rail has a step surface formed between the first guide surface and the first side surface in the width direction, 2. The image forming apparatus according to claim 1, wherein the step surface has a regulating portion that abuts against the protruding rib to regulate the trajectory of the arm when the process cartridge is attached to the main body of the apparatus to a position where the arm does not interfere with the boss in a retracted position.

11. The device body includes: a top cover for covering an upper surface of the device body; an exposure unit supported by the top cover and configured to expose the photosensitive drum; the first frame has a first side surface facing the process cartridge in the axial direction, the first guide rail has a first guide surface located outboard of the first side surface in the axial direction, a first step surface formed between one end of the first guide surface in the width direction and the first side surface, and a second step surface formed between the other end of the first guide surface in the width direction and the first side surface, the first step surface has a first positioning portion that comes into contact with the exposure unit to restrict movement of the exposure unit to one side in a horizontal direction perpendicular to the axial direction, and a third positioning portion that comes into contact with the protruding rib to restrict movement of the process cartridge to one side in the width direction, the second step surface has a second positioning portion that comes into contact with the exposure unit to restrict movement of the exposure unit to the other side in a horizontal direction perpendicular to the axial direction, and a fourth positioning portion that comes into contact with the protruding rib to restrict movement of the process cartridge to the other side in the width direction, An image forming apparatus according to any one of claims 1 to 10, wherein the third positioning portion and the fourth positioning portion are arranged downstream of the first positioning portion and the second positioning portion in the mounting direction of the process cartridge relative to the main body of the apparatus.

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