Image forming apparatus

Abstract

The present invention provides an image forming apparatus that can suppress the load placed on the drum unit's support section by the developing cartridge. [Solution] The image forming apparatus comprises a main body housing, a drum unit 50 detachable from the main body housing, and a developing cartridge 60 detachable from the drum unit 50. The drum unit 50 has a support portion 54 that contacts the developing housing 65 of the developing cartridge 60 and supports the developing cartridge 60. The developing cartridge 60 is movable relative to the drum unit 50 while in contact with the support portion 54, between a contact position where the developing roller 61 contacts the photosensitive drum 51 and a separation position where the developing roller 61 separates from the photosensitive drum 51. The image forming apparatus further comprises a first spacer 130 that, while sandwiched between the first side frame 531 of the drum unit 50 and the developing housing 65, separates the developing roller 61 from the photosensitive drum 51 and separates the developing housing 65 from the support portion 54.

Description

[Technical Field]

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

[0002] As an image forming apparatus, one including a main body casing, a drum unit detachably attachable to the main body casing, and a developing cartridge detachably attachable to the drum unit is known (Patent Document 1). In this technique, the drum unit has a support portion that supports the developing cartridge when the developing cartridge is mounted on the drum unit. The support portion is a rotatably held roller. [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2024-116676 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] Incidentally, when a load is continuously applied from the developing cartridge to the support portion of the drum unit during storage of the image forming apparatus or the like, the support portion may be deformed. Therefore, it is desired to be able to suppress application of a load from the developing cartridge to the support portion of the drum unit. [Means for Solving the Problem]

[0005] In the first disclosure of the present application, the image forming apparatus includes a main body casing, a drum unit detachably attachable to the main body casing, and a developing cartridge detachably attachable to the drum unit. The drum unit includes a photosensitive drum rotatable around an axially extending drum shaft, and a first side frame positioned on one axial side with respect to the photosensitive drum. The developing cartridge includes a developing housing that accommodates toner, and a developing roller that supplies toner to the photosensitive drum. The drum unit has a support portion that contacts the developing housing and supports the developing cartridge. The developing cartridge is movable relative to the drum unit while in contact with the support, between a contact position and a separated position. At the contact point, the developing roller comes into contact with the photosensitive drum. At the separated position, the developing roller separates from the photosensitive drum. The image forming apparatus further comprises a first spacer. The first spacer, while sandwiched between the first side frame and the developing housing, separates the developing roller from the photosensitive drum and separates the developing housing from the support.

[0006] The image forming apparatus includes a first spacer that separates the developing housing from the support. This prevents the load from the developing cartridge from being placed on the support of the drum unit.

[0007] In the second disclosure of this application, in the image forming apparatus of the first disclosure, the first side frame has a first contact portion. The first contact area consists of two intersecting surfaces, which the first spacer contacts. The developing housing has a second contact portion. The second contact point faces the first contact point. The first spacer is sandwiched between the two surfaces of the first contact area and the second contact area.

[0008] The first spacer is sandwiched between the two surfaces of the first contact portion of the first side frame and the second contact portion of the developing housing. This prevents the first spacer from shifting position.

[0009] In the third disclosure of this application, in the image forming apparatus of the second disclosure, the developing cartridge has a memory, a holder, and a holder cover at one end in the axial direction. The holder holds the memory. The holder cover covers the holder. The holder cover has a second contact portion.

[0010] In the fourth disclosure of this application, in the image forming apparatus of the first disclosure, the first spacer engages between the first side frame and the developing housing from one side to the other in the axial direction. The image forming apparatus further comprises a cover having a first spacer and a retaining portion. The retaining portion protrudes from the first spacer on one side in the axial direction. The retaining portion contacts the main housing in the axial direction.

[0011] The cover having the first spacer has a retaining portion that protrudes beyond the first spacer and contacts the main housing in the axial direction. This makes it difficult for the cover to come off in the axial direction.

[0012] In the fifth disclosure of this application, the image forming apparatus in the first disclosure further comprises a cover having a first spacer and a first hook. The first hook extends in a direction perpendicular to the axial direction. The first hook engages with the developing housing.

[0013] The cover having the first spacer has a first hook that extends in a direction perpendicular to the axial direction and engages with the developing housing. This makes it difficult for the cover to come off in a direction perpendicular to the axial direction.

[0014] In the sixth disclosure of this application, the image forming apparatus in the first disclosure further comprises a cover having a first spacer and a second hook. The second hook extends axially toward the other side. The second hook engages with the first side frame.

[0015] The cover having the first spacer has a second hook that extends axially toward the other side and engages with the first side frame. This makes it difficult for the cover to come off axially.

[0016] In the seventh disclosure of this application, in the image forming apparatus of the first disclosure, the drum unit has a second side frame and a connecting frame. The second side frame is located on the other axial side relative to the photosensitive drum. The connection frame extends in the axial direction and connects the first side frame and the second side frame. The image forming apparatus further includes a cover having a first spacer and a buffer portion. The buffer portion is interposed between the developing housing and the connection frame. The buffer portion is smaller than the gap between the developing housing and the connection frame.

[0017] The cover having the first spacer is interposed between the developing housing and the connection frame, and includes a buffer portion smaller than the gap between the developing housing and the connection frame. Thereby, the buffer portion does not hinder the function of the first spacer.

[0018] In an eighth disclosure of the present application, in the image forming apparatus according to the first disclosure, the developing housing has a supported surface. The supported surface extends along a movement direction when the developing cartridge moves between a contact position and a separated position. The supported surface is in contact with the support portion.

[0019] The developing housing has a supported surface that extends along the movement direction when the developing cartridge moves between the contact position and the separated position and is in contact with the support portion. Thereby, the developing cartridge can smoothly move between the contact position and the separated position.

[0020] In a ninth disclosure of the present application, in the image forming apparatus according to the eighth disclosure, the support portion is a roller rotatable around a roller shaft extending in the axial direction. The roller rotates when the developing cartridge moves between the contact position and the separated position.

[0021] The roller serving as the support portion rotates when the developing cartridge moves between the contact position and the separated position. Thereby, the developing cartridge can smoothly move between the contact position and the separated position.

[0022] In a tenth disclosure of the present application, in the image forming apparatus according to the first disclosure, the drum unit includes the second side frame. The second side frame is located on the other side in the axial direction relative to the photosensitive drum. The developing cartridge has a coupling at its other axial end for inputting driving force to the developing roller. The developing housing is a cylindrical bearing on which the coupling is positioned, and has a bearing that protrudes in the axial direction. The image forming apparatus further includes a second spacer. The second spacer, while sandwiched between the second side frame and the bearing, separates the developing roller from the photosensitive drum and also separates the developing housing from the support.

[0023] The image forming apparatus includes a second spacer that separates the developing housing from the support. This prevents the load from the developing cartridge from being placed on the support of the drum unit.

[0024] In the eleventh disclosure of this application, in the image forming apparatus of the first disclosure, the first side frame has a first surface. The first surface is located below the first spacer. The developing enclosure has a second side. The second surface is located above the first surface. The second surface is separated from the first surface by a first spacer. The maximum vertical length of the portion of the first spacer sandwiched between the first and second surfaces is greater than the maximum vertical distance between the first and second surfaces when the developing cartridge is in contact position. [Effects of the Invention]

[0025] This helps to suppress the load placed on the drum unit's support section by the developing cartridge. [Brief explanation of the drawing]

[0026] [Figure 1] This is a diagram showing the schematic configuration of an image forming apparatus. [Figure 2] This is a perspective view showing the cover attached to the drum unit. [Figure 3] This is a perspective view showing the cover removed from the drum unit. [Figure 4] (a) is a cross-sectional view showing a developing cartridge located in contact with the drum unit, and (b) is a cross-sectional view showing a developing cartridge located at a distance from the drum unit. [Figure 5] These are perspective views (a) and (b) showing the first cover. [Figure 6] This is a cross-sectional view showing the buffer section with the first cover attached to the drum unit. [Figure 7] This diagram shows the first spacer, developing roller, and support section with the first cover attached to the drum unit. [Figure 8] Figure (a) shows the first spacer, first contact point, and second contact point when the first cover is attached to the drum unit, and Figure (b) shows the first contact point and second contact point when the developing cartridge is in the contact position. [Figure 9] This is a perspective view showing one end of the developing cartridge in the first direction. [Figure 10] This is a view of the first cover attached to the drum unit, seen from one side in the third direction. [Figure 11] This is a cross-sectional perspective view showing the first hook. [Figure 12] This is a cross-sectional perspective view showing the second hook. [Figure 13] This is a view of the drum unit and developing cartridge from the other side in the first direction. [Figure 14] These are perspective views (a) and (b) showing the second cover. [Figure 15] This figure shows the second spacer with the second cover attached to the drum unit. [Figure 16] These are cross-sectional views (a) and (b) showing modified versions of the support structure. [Modes for carrying out the invention]

[0027] Next, embodiments will be described. As shown in Figure 1, the image forming apparatus 1 is a color printer capable of forming color images on a sheet S such as paper. The image forming apparatus 1 comprises a main body housing 10, a main body cover 11, a sheet supply unit 20, and an image forming unit 30.

[0028] In the referenced drawings, the first direction (see Figure 2), the second direction, and the third direction are indicated by arrows, with the arrow indicating one direction and the other by the arrowless direction. In this embodiment, the first direction corresponds to the "axial direction".

[0029] The second direction is the direction that intersects the first direction. In this embodiment, the second direction is perpendicular to the first direction. The third direction is a direction that intersects both the first and second directions. In the embodiment, the third direction is perpendicular to both the first and second directions. In the embodiment, the third direction corresponds to the up and down direction. One side of the third direction corresponds to the up side, and the other side of the third direction corresponds to the down side.

[0030] The main housing 10 has an opening 10A. The main cover 11 opens and closes the opening 10A. The main cover 11 is movable relative to the main housing 10 between a closed position shown by a solid line and an open position shown by a dashed line. Specifically, the main cover 11 is rotatable relative to the main housing 10 between the closed position and the open position. The closed position is the position in which the opening 10A is closed. The open position is the position in which the opening 10A is opened.

[0031] The sheet supply unit 20 includes a sheet tray 21 and a sheet supply mechanism 22. The seat tray 21 accommodates the seat S. The sheet supply mechanism 22 includes a pickup roller 23, a separation roller 24, a separation pad 25, a transport roller 26, and a registration roller 27.

[0032] The pickup roller 23 pushes the seat S out of the seat tray 21. The separation roller 24 and separation pad 25 separate the sheet S fed out by the pickup roller 23 into individual sheets. The transport roller 26 and registration roller 27 transport the sheet S to the image forming unit 30.

[0033] The image forming unit 30 comprises an exposure unit 40, a drum unit 50, four developing cartridges 60, a transfer unit 70, and a fixing unit 80. The exposure unit 40 includes a light source, a deflector, a lens, a mirror, and the like. The exposure unit 40 emits a light beam as shown by the dashed line to expose the surface of the photosensitive drum 51.

[0034] The drum unit 50 has four photosensitive drums 51 and four chargers 52. A toner image is formed on the surface of the photosensitive drum 51. The photosensitive drum 51 is rotatable around a drum shaft 51X extending in a first direction. The photosensitive drum 51 includes a photosensitive drum 51K, a photosensitive drum 51C, a photosensitive drum 51M, and a photosensitive drum 51Y.

[0035] The four photosensitive drums 51 are arranged in the order of photosensitive drum 51Y, photosensitive drum 51M, photosensitive drum 51C, and photosensitive drum 51K, from one end of the second direction to the other. The four photosensitive drums 51 are also arranged in the order of photosensitive drum 51Y, photosensitive drum 51M, photosensitive drum 51C, and photosensitive drum 51K, from upstream to downstream in the conveying direction of the sheet S.

[0036] The drum unit 50 is detachable from the main body housing 10. Specifically, the drum unit 50 is detachable from the main body housing 10 through the opening 10A when the main body cover 11 is in the open position indicated by the dashed line.

[0037] The developing cartridge 60 includes a developing roller 61 and a developing housing 65. The developing roller 61 supplies toner to the photosensitive drum 51. The developing unit 65 houses the toner. The developing unit 65 rotatably holds the developing roller 61.

[0038] The developing cartridge 60 includes developing cartridge 60K, developing cartridge 60C, developing cartridge 60M, and developing cartridge 60Y. Developing cartridges 60K, 60C, 60M, and 60Y are individually detachable from the drum unit 50.

[0039] The developing unit 65K houses the black toner. The developing roller 61K supplies the black toner to the photosensitive drum 51K. The developing unit 65C houses the cyan toner. The developing roller 61C supplies the cyan toner to the photosensitive drum 51C.

[0040] The developing unit 65M houses the magenta toner. The developing roller 61M supplies the magenta toner to the photosensitive drum 51M. The developing unit 65Y houses the yellow toner. The developing roller 61Y supplies the yellow toner to the photosensitive drum 51Y.

[0041] In the following explanation, when distinguishing between the colors black, cyan, magenta, and yellow for each component, the codes K, C, M, and Y will be added, respectively. Conversely, when the colors of each component are not distinguished, the codes K, C, M, and Y will not be added.

[0042] The transfer unit 70 comprises a drive roller 71, a driven roller 72, an endless transfer belt 73, and four transfer rollers 74. The transfer belt 73 is stretched between the drive roller 71 and the driven roller 72. The outer surface of the transfer belt 73 is in contact with the photosensitive drum 51. The transfer roller 74 is positioned inside the transfer belt 73. The transfer roller 74 sandwiches the transfer belt 73 between itself and the photosensitive drum 51.

[0043] The fixing unit 80 includes a heating roller 81 and a pressure roller 82. The heating roller 81 heats the sheet S. The pressure roller 82 sandwiches the sheet S between itself and the heating roller 81.

[0044] The charger 52 charges the surface of the photosensitive drum 51. The exposure unit 40 emits a light beam onto the charged surface of the photosensitive drum 51. This forms an electrostatic latent image on the photosensitive drum 51 based on the image data. The developing roller 61 supplies toner to the surface of the exposed photosensitive drum 51. This forms a toner image on the photosensitive drum 51.

[0045] The photosensitive drum 51 and transfer roller 74 transport the sheet S supplied from the registration roller 27. This transfers the toner image formed on the photosensitive drum 51 to the sheet S. The heating roller 81 and pressure roller 82 transport the sheet S with the transferred toner image. This fixes the transferred toner image to the sheet S. The intermediate discharge roller 15 and discharge roller 16 discharge the sheet S with the fixed toner image to the discharge tray 13.

[0046] As shown in Figures 2 and 3, the image forming apparatus 1 further comprises a first cover CV1, a second cover CV2, a third cover CV3, and a fourth cover CV4. In this embodiment, the first cover CV1 corresponds to a "cover". The drum unit 50 has a drum frame 53.

[0047] Covers CV1 to CV4 are attached to the drum unit 50. Covers CV1 to CV4 are removable from the drum unit 50. Covers CV1 to CV4 are attached when transporting the image forming apparatus 1, etc., to suppress unnecessary contact between components. Covers CV1 to CV4 are removed when using the image forming apparatus 1. Covers CV1 to CV4 are detachable from the drum unit 50.

[0048] The drum frame 53 rotatably supports the photosensitive drum 51. The drum frame 53 has a first side frame 531, a second side frame 532, a first connecting frame 533, and a second connecting frame 534. In this embodiment, the first connecting frame 533 corresponds to the "connecting frame".

[0049] The first side frame 531 is located on one side in a first direction relative to the photosensitive drum 51. The first side frame 531 extends in a second direction. The second side frame 532 is located on the other side of the photosensitive drum 51 in the first direction. The second side frame 532 extends in the second direction. The first side frame 531 and the second side frame 532 face each other in the first direction.

[0050] The first connecting frame 533 is located at the other end of the drum frame 53 in the second direction. The first connecting frame 533 extends in the first direction. The first connecting frame 533 connects the first side frame 531 and the second side frame 532. More specifically, the first connecting frame 533 connects the other end of the first side frame 531 in the second direction to the other end of the second side frame 532 in the second direction.

[0051] The second connecting frame 534 is located at one end of the drum frame 53 in the second direction. The second connecting frame 534 extends in the first direction. The second connecting frame 534 connects one end of the first side frame 531 in the second direction to one end of the second side frame 532 in the second direction. The first connecting frame 533 and the second connecting frame 534 face each other in the second direction.

[0052] As shown in Figures 4(a) and 4(b), each developing cartridge 60 is movable relative to the drum unit 50 between a contact position and a separation position. The contact position shown in Figure 4(a) is the position where the developing roller 61 contacts the photosensitive drum 51. The developing roller 61 can supply toner to the photosensitive drum 51 when the developing cartridge 60 is in the contact position. The separation position shown in Figure 4(b) is the position where the developing roller 61 is separated from the photosensitive drum 51.

[0053] The drum unit 50 has a support portion 54. The support portion 54 contacts the developing housing 65 and supports the developing cartridge 60. In this embodiment, the support portion 54 has a support member 541 and an elastic member 542.

[0054] The support member 541 contacts the developing housing 65 from below when the developing cartridge 60 is mounted on the drum unit 50. The surface of the support member 541 that contacts the developing housing 65 is spherical in shape. The support member 541 is held on the drum frame 53 so as to be movable in a direction intersecting the direction of movement of the developing cartridge 60. In this embodiment, the support member 541 is held on the drum frame 53 so as to be movable in a direction perpendicular to the direction of movement of the developing cartridge 60.

[0055] The elastic member 542 biases the support member 541 toward the developing housing 65. In this embodiment, the elastic member 542 is a compression coil spring.

[0056] The developing cartridge 60 is movable relative to the drum unit 50 while in contact with the support portion 54, between the contact position shown in Figure 4(a) and the separated position shown in Figure 4(b). The developing cartridge 60 is movable relative to the drum frame 53 while in contact with the support member 541, between the contact position and the separated position.

[0057] The developing housing 65 has a supported surface 651. The supported surface 651 is the surface that contacts the support portion 54. The supported surface 651 extends along the direction of movement when the developing cartridge 60 moves between a contact position and a separated position.

[0058] In this embodiment, the drum unit 50 has four support sections 54 on one side and four on the other side in the first direction, corresponding to the four developing cartridges 60. In addition, each developing housing 65 has one supported surface 651 on one side and one on the other side in the first direction.

[0059] As shown in Figures 5(a) and (b), the first cover CV1 has a first buffer portion 111, three second buffer portions 112, and a third buffer portion 113. In this embodiment, the first buffer portion 111 corresponds to a "buffer portion". The first cover CV1 further has four first connecting portions 120, four first spacers 130, and four second connecting portions 140. The first cover CV1 further has four retaining portions 150, four first hooks 160, and four second hooks 170. The first cover CV1 is made of a resin such as polypropylene, for example.

[0060] As shown in Figure 6, the first buffer portion 111 is located between the developing housing 65K and the first connecting frame 533. In the second direction, the length L11 of the first buffer portion 111 is smaller than the gap D11 between the developing housing 65K and the first connecting frame 533. The developing housing 65K can come into contact with the first buffer portion 111 when the image forming apparatus 1 is subjected to impact, such as when transporting the image forming apparatus 1.

[0061] The second buffer portion 112 is located between adjacent developing housings 65 in the second direction. In the second direction, the length L12 of the second buffer portion 112 is smaller than the gap D12 between adjacent developing housings 65. The developing housing 65 can come into contact with the second buffer portion 112 when an impact is applied to the image forming apparatus 1.

[0062] The third buffer portion 113 is located between the developing housing 65Y and the second connecting frame 534. In the second direction, the length L13 of the third buffer portion 113 is smaller than the gap D13 between the developing housing 65Y and the second connecting frame 534. The developing housing 65Y can come into contact with the third buffer portion 113 when an impact is applied to the image forming apparatus 1.

[0063] The first connecting portion 120 has a plate shape. The first connecting portion 120 includes a first connecting portion 121, two first connecting portions 122, and a first connecting portion 123. The first connecting portion 121 connects the first buffer portion 111 and the second buffer portion 112. The first connecting portion 122 connects adjacent second buffer portions 112 in the second direction. The first connecting portion 123 connects the second buffer portion 112 and the third buffer portion 113.

[0064] As shown in Figure 7, the first spacer 130, sandwiched between the first side frame 531 and the developing housing 65, separates the developing roller 61 from the photosensitive drum 51. Furthermore, the first spacer 130, sandwiched between the first side frame 531 and the developing housing 65, separates the developing housing 65 from the support portion 54. The first spacer 130 engages between the first side frame 531 and the developing housing 65 from one side to the other in the first direction.

[0065] As shown in Figure 8(a), the first spacer 130 has a box shape consisting of an upper wall and a peripheral wall extending downward from the periphery of the upper wall.

[0066] The first side frame 531 has a first contact portion 210. The first contact portion 210 consists of two surfaces. Specifically, the first contact portion 210 has a first contact surface 211 and a second contact surface 212. In an embodiment, the first contact surface 211 corresponds to the "first surface". The first contact surface 211 and the second contact surface 212 intersect each other. In an embodiment, the first contact surface 211 and the second contact surface 212 are perpendicular to each other.

[0067] The first contact surface 211 is a surface that intersects in the third direction. In this embodiment, the first contact surface 211 is perpendicular to the third direction. The first contact surface 211 extends in the second direction. The second contact surface 212 is a surface that intersects in the second direction. In this embodiment, the second contact surface 212 is perpendicular to the second direction. The second contact surface 212 extends in the third direction. The second contact surface 212 extends from the other end of the first contact surface 211 in the second direction toward one end in the third direction.

[0068] The first spacer 130 is in contact with the first contact surface 211 and the second contact surface 212. The first contact surface 211 is located on the other side of the first spacer 130 in the third direction. Specifically, the first contact surface 211 is located on the underside of the first spacer 130. The second contact surface 212 is located on the other side of the first spacer 130 in the second direction.

[0069] The developing housing 65 has a second contact portion 220. The second contact portion 220 faces the first contact portion 210 when the developing cartridge 60 is mounted on the drum unit 50. The second contact portion 220 has a contact surface 221. In this embodiment, the contact surface 221 corresponds to the "second surface". The contact surface 221 faces the first contact surface 211 and the second contact surface 212. The contact surface 221 sandwiches the first spacer 130 between the first contact surface 211 and the second contact surface 212. The contact surface 221 is located above the first contact surface 211.

[0070] As shown in Figure 9, the developing cartridge 60 has a memory 66, a holder 67, and a holder cover 65B at one end in the first direction. In this embodiment, the developing housing 65 has a developing housing body 65A that houses the toner and a holder cover 65B.

[0071] Memory 66 is, for example, an IC chip. Memory 66 stores information about the developing cartridge 60. Information about the developing cartridge 60 includes, for example, information about the developing roller 61 and information about the lifespan of the developing cartridge 60. Information about the developing roller 61 includes, for example, the manufacturing date, manufacturing location, and maximum number of rotations that can be used. Information about the lifespan of the developing cartridge 60 includes, for example, the cumulative number of rotations of the developing roller 61 and the cumulative number of prints using the developing cartridge 60.

[0072] The holder 67 holds the memory 66. The holder cover 65B covers the holder 67. The holder cover 65B covers the upper part of one end of the developing housing body 65A in the first direction. The holder 67 is located between the developing housing body 65A and the holder cover 65B in the first direction. The developing housing 65 holds the holder 67 so that it can move in the second and third directions. The holder cover 65B has a second contact portion 220.

[0073] Returning to Figure 8(a), the first spacer 130 is sandwiched between the two surfaces 211 and 212 of the first contact portion 210 and the contact surface 221 of the second contact portion 220. The first maximum length L1 shown in Figure 8(a) is greater than the first maximum distance D1 shown in Figure 8(b). The first maximum length L1 is the maximum vertical length of the portion of the first spacer 130 that is sandwiched between the first contact surface 211 and the contact surface 221. The first maximum distance D1 is the maximum vertical distance from the first contact surface 211 to the contact surface 221 when the developing cartridge 60 is in the contact position.

[0074] As shown in Figures 5(a) and 5(b), the second connecting portion 140 connects the first buffer portion 111 or the second buffer portion 112 to the corresponding first spacer 130. The second connecting portion 140 has a plate shape. The second connecting portion 140 has a first extension portion 141, a second extension portion 142, and a third extension portion 143.

[0075] The first extension 141 extends from one end in the first direction to one end in the second direction of the first buffer portion 111 or the second buffer portion 112. The second extension 142 extends from the other end of the first extension 141 in the third direction to one end in the first direction. The third extension 143 extends from one end of the second extension 142 in the first direction to the other end in the third direction and connects to the first spacer 130.

[0076] The second connecting portion 140 further has ribs 144 and 145 extending in the third direction. The rib 144 protrudes from the first extension 141 in one direction in the first direction. Multiple ribs 144 are arranged in a second direction. Specifically, two ribs 144 are arranged in a second direction.

[0077] The rib 145 protrudes from the third extension 143 in the other direction in the first direction. Multiple ribs 145 are arranged in the second direction. Specifically, two ribs 144 are arranged in the second direction. The presence of ribs 144 and 145 improves the rigidity of the second connecting portion 140. This prevents, for example, the first spacer 130 from coming out to one side in the first direction due to deformation of the second connecting portion 140.

[0078] The retaining portion 150 protrudes from one end of the third extension portion 143 in the third direction. More specifically, the retaining portion 150 extends diagonally from the third extension portion 143 toward one direction in the first direction and the other direction in the second direction. Furthermore, the retaining portion 150 is bent and extends diagonally toward the other direction in the first direction and the other direction in the second direction.

[0079] The retaining portion 150 protrudes from the first spacer 130 on one side in the first direction. The retaining portion 150 protrudes from the second connecting portion 140 on one side in the first direction. As shown in Figure 10, the retaining portion 150 is in contact with the inner surface of the main housing 10, indicated by the dashed line, in the first direction. The retaining portion 150 is in contact with the inner surface of the main housing 10 from the other side in the first direction.

[0080] As shown in Figure 11, the first hook 160 engages with the developing housing 65. The first hook 160 extends in a third direction perpendicular to the first direction. More specifically, the first hook 160 extends from the first connecting portion 120 to the other in the third direction. The first hook 160 has a claw 161 at its tip that engages with the developing housing 65. The claw 161 protrudes from the tip of the first hook 160 to the other in the second direction. In this embodiment, the claw 161 engages with the holder cover 65B.

[0081] As shown in Figure 12, the second hook 170 engages with the first side frame 531. The second hook 170 extends from the other end of the first spacer 130 in the third direction toward the other side in the first direction. The second hook 170 has a claw 171 at its tip that engages with the first side frame 531. The claw 171 protrudes from the tip of the second hook 170 toward the other side in the third direction.

[0082] As shown in Figure 13, the drum unit 50 has a drum coupling 55 at the other end in the first direction. The drum coupling 55 is a component for inputting driving force to the photosensitive drum 51. The drum coupling 55 is located at the other end of the photosensitive drum 51 in the first direction.

[0083] The developing cartridge 60 has a developing coupling 68 at the other end in the first direction. In this embodiment, the developing coupling 68 corresponds to a "coupling". The developing coupling 68 is a component for inputting driving force to the developing roller 61. The developing coupling 68 is rotatably held in the developing housing 65.

[0084] The developing housing 65 has a bearing 652 at the other end in the first direction. The bearing 652 has a cylindrical shape. More specifically, the bearing 652 has a cylindrical shape. The bearing 652 protrudes to the other side in the first direction. A developing coupling 68 is positioned on the bearing 652. The bearing 652 rotatably holds the developing coupling 68.

[0085] The second side frame 532 has a recess 56. The recess 56 receives the bearing 652 when the developing cartridge 60 is mounted on the drum unit 50. The recess 56 opens toward one side in a third direction. The recess 56 has an opposing surface 561. The opposing surface 561 is located on the other side of the bearing 652 in a second direction when the developing cartridge 60 is mounted on the drum unit 50. The opposing surface 561 faces the bearing 652 in a second direction when the developing cartridge 60 is mounted on the drum unit 50.

[0086] As shown in Figures 14(a) and (b), the second cover CV2 has four cover walls 310, three connecting parts 320, and four cylindrical parts 330. The second cover CV2 is made of a resin such as polypropylene.

[0087] The cover wall 310 is a wall that covers the second side frame 532 from the other side in the first direction. Specifically, as shown in Figure 15, the cover wall 310 covers the drum coupling 55 and the developing coupling 68 from the other side in the first direction. Returning to Figures 14(a) and (b), the connection section 320 connects adjacent cover walls 310 in the second direction.

[0088] The cylindrical portion 330 has a cylindrical shape. The cylindrical portion 330 protrudes from the cover wall 310 in one direction in the first direction. The cylindrical portion 330 has a second spacer 331. The second spacer 331 protrudes in the second direction. The second spacer 331 is also connected to the cover wall 310.

[0089] As shown in Figure 15, the cylindrical portion 330 engages with the bearing 652 of the developing cartridge 60. The second spacer 331 is sandwiched between the opposing surface 561 of the second side frame 532 and the bearing 652 while the cylindrical portion 330 is engaged with the bearing 652.

[0090] The second spacer 331, sandwiched between the opposing surface 561 and the bearing 652, separates the developing roller 61 from the photosensitive drum 51, as shown in Figure 7. Furthermore, the second spacer 331, sandwiched between the opposing surface 561 and the bearing 652, separates the developing housing 65 from the support portion 54. The second spacer 331 engages between the second side frame 532 and the bearing 652, moving from one side to the other in the first direction.

[0091] The second maximum length L2 shown in Figure 15 is greater than the second maximum distance D2 shown in Figure 13. The second maximum length L2 is the maximum length in the second direction of the portion of the second spacer 331 sandwiched between the opposing surface 561 and the bearing 652. The second maximum distance D2 is the maximum distance in the second direction from the opposing surface 561 to the bearing 652 when the developing cartridge 60 is in the contact position.

[0092] Next, the effects and advantages of the embodiment will be described. The image forming apparatus 1 includes a first spacer 130 that separates the developing housing 65 from the support portion 54. This prevents the load from being placed on the support portion 54 of the drum unit 50 by the developing cartridge 60.

[0093] The first spacer 130 is sandwiched between the two surfaces 211 and 212 of the first contact portion 210 of the first side frame 531 and the contact surface 221 of the second contact portion 220 of the developing housing 65. This prevents the first spacer 130 from shifting position.

[0094] The first cover CV1, which has a first spacer 130, has a retaining portion 150 that protrudes beyond the first spacer 130 and contacts the main body housing 10 in a first direction. This makes it difficult for the first cover CV1 to come off in the first direction.

[0095] The first cover CV1 has a first hook 160 that extends in a third direction and engages with the developing housing 65. This makes it difficult for the first cover CV1 to come off in the third direction.

[0096] The first cover CV1 has a second hook 170 that extends toward the other side in the first direction and engages with the first side frame 531. This makes it difficult for the first cover CV1 to come off in the first direction.

[0097] The first cover CV1 is positioned between the developing housing 65 and the first connecting frame 533 and has a first buffer portion 111 that is smaller than the gap D11 between the developing housing 65 and the first connecting frame 533. This ensures that the first buffer portion 111 does not interfere with the function of the first spacer 130. When the developing housing 65K comes into contact with the first buffer portion 111, rattling of the developing cartridge 60K can be suppressed.

[0098] The first cover CV1 fits between adjacent developing housings 65 in the second direction and has a second buffer portion 112 that is smaller than the gap D12 between adjacent developing housings 65. As a result, the second buffer portion 112 does not interfere with the function of the first spacer 130. When the developing housing 65 comes into contact with the second buffer portion 112, rattling of the developing cartridge 60 can be suppressed.

[0099] The first cover CV1 is positioned between the developing housing 65Y and the second connecting frame 534 and has a third buffer portion 113 that is smaller than the gap D13 between the developing housing 65Y and the second connecting frame 534. This prevents the third buffer portion 113 from interfering with the function of the first spacer 130. When the developing housing 65Y comes into contact with the third buffer portion 113, rattling of the developing cartridge 60Y can be suppressed.

[0100] The developing housing 65 has a supported surface 651 that extends along the direction of movement when the developing cartridge 60 moves between a contact position and a separated position, and contacts the support portion 54. This allows the developing cartridge 60 to move smoothly between the contact position and the separated position.

[0101] The image forming apparatus 1 includes a second spacer 331 that separates the developing housing 65 from the support portion 54. This prevents the load from being placed on the support portion 54 of the drum unit 50 by the developing cartridge 60.

[0102] Although embodiments have been described above, the image forming apparatus can be modified as appropriate, as illustrated below.

[0103] In the embodiment, the support portion 54 had a support member 541 that contacts the developing housing 65 and an elastic member 542 that biases the support member 541 toward the developing housing 65. However, as shown in Figure 16(a), for example, the support portion may be a roller 54R. The roller 54R is rotatable around a roller shaft 54X that extends in a first direction. The roller 54R as a support portion rotates when the developing cartridge 60 moves between the contact position shown in Figure 16(a) and the separated position shown in Figure 16(b). This allows the developing cartridge 60 to move smoothly between the contact position and the separated position.

[0104] Furthermore, for example, the support portion may be a projection that protrudes toward the developing housing. It is desirable that the surface of the projection that contacts the developing housing has a spherical shape.

[0105] In the embodiment, the first cover CV1, which serves as a cover, had buffer portions 111-113 to suppress rattling of the developing cartridge 60 when it came into contact with the developing housing 65. However, for example, the cover does not have to have buffer portions 111-113. Also, for example, the cover does not have to have a retaining portion 150. Also, for example, the cover does not have to have a first hook 160. Also, for example, the cover does not have to have a second hook 170.

[0106] In this embodiment, the image forming apparatus 1 included the first spacer 130 as part of the first cover CV1. However, for example, the image forming apparatus may include the first spacer as an independent component rather than as part of the first cover CV1.

[0107] In the embodiment, the image forming apparatus 1 included the second spacer 331 as part of the second cover CV2. However, for example, the image forming apparatus may include the second spacer as an independent component rather than as part of the second cover CV2.

[0108] In the embodiment, the image forming apparatus 1 was provided with a first spacer 130 on one side in the first direction and a second spacer 331 on the other side in the first direction. However, for example, the image forming apparatus may not have a second spacer and may have first spacers on both sides in the first direction, sandwiched between the side frame and the developing housing. In this case, the first spacer and the structure sandwiching the first spacer between the side frame and the developing housing may have a shape that is symmetrical with respect to a plane perpendicular to the first direction. The first spacer on the other side in the first direction may be, for example, a third cover CV3.

[0109] In this embodiment, the holder cover 65B had the second contact portion 220, but for example, the developing housing body 65A may have the second contact portion. If the developing housing body 65A has the second contact portion, the developing cartridge 60 does not need to have the memory 66, the holder 67, and the holder cover 65B.

[0110] In the embodiment, the first spacer 130 was sandwiched between two surfaces 211, 212 of the first contact portion 210 and one surface 221 of the second contact portion 220. However, for example, the first spacer may be sandwiched between one surface of the first contact portion and two surfaces of the second contact portion. Alternatively, for example, the first spacer may be sandwiched between multiple surfaces of the first contact portion and multiple surfaces of the second contact portion. Alternatively, for example, the first spacer may be sandwiched between one surface of the first contact portion and one surface of the second contact portion.

[0111] In the embodiment, the image forming apparatus 1 was a printer capable of forming color images, but for example, the image forming apparatus may be a printer capable of forming only monochrome images. In other words, in the embodiment, the image forming apparatus 1 had four first spacers 130, but for example, the image forming apparatus may have only one first spacer. Also, in the embodiment, the image forming apparatus 1 had four second spacers 331, but for example, the image forming apparatus may have only one second spacer. The image forming apparatus may be a copier, a multifunction printer, or the like.

[0112] The elements described in the embodiments and modifications may be implemented in any combination. [Explanation of Symbols]

[0113] 1. Image forming apparatus 10 Main Unit 50 Drum Units 51 Photosensitive drum 51X Drum shaft 54 Support part 60 developing cartridges 61 Developing roller 65 Developing cabinet 130 First Spacer 531 First side frame

Claims

1. The main casing and A drum unit that can be attached to and detached from the main body housing, A photosensitive drum that is rotatable around a drum shaft extending in the axial direction, The photosensitive drum has a first side frame located on one side in the axial direction. Drum unit and, A developing cartridge that can be attached to and detached from the drum unit, A developing unit that houses the toner, A developing roller that supplies toner to the photosensitive drum, Equipped with a developing cartridge, The drum unit has a support portion that contacts the developing housing and supports the developing cartridge, The developing cartridge is movable relative to the drum unit while in contact with the support portion, between a contact position in which the developing roller contacts the photosensitive drum and a separation position in which the developing roller is separated from the photosensitive drum. The image forming apparatus is further characterized by comprising a first spacer that, while sandwiched between the first side frame and the developing housing, separates the developing roller from the photosensitive drum and separates the developing housing from the support portion.

2. The first side frame has a first contact portion consisting of two intersecting surfaces, the two surfaces to which the first spacer makes contact. The developing housing has a second contact portion that faces the first contact portion, The image forming apparatus according to claim 1, characterized in that the first spacer is sandwiched between the two surfaces of the first contact portion and the second contact portion.

3. The developing cartridge has, at one end in the axial direction, Memory and A holder for holding the aforementioned memory, The holder has a holder cover that covers the holder, The image forming apparatus according to claim 2, characterized in that the holder cover has the second contact portion.

4. The first spacer engages between the first side frame and the developing housing from one side to the other in the axial direction. The image forming apparatus according to claim 1, further comprising a cover having the first spacer and a retaining portion that protrudes from the first spacer on one side in the axial direction and contacts the main body housing in the axial direction.

5. The image forming apparatus according to claim 1, further comprising a cover having the first spacer and a first hook extending in a direction perpendicular to the axial direction, the first hook engaging with the developing housing.

6. The image forming apparatus according to claim 1, further comprising a cover having the first spacer and a second hook extending toward the other side in the axial direction, the second hook engaging with the first side frame.

7. The drum unit is A second side frame located on the other side in the axial direction relative to the photosensitive drum, It has a connecting frame that extends in the axial direction and connects the first side frame and the second side frame, The image forming apparatus according to claim 1, further comprising the first spacer and a cover having a buffer portion that fits between the developing housing and the connecting frame, and which is smaller than the gap between the developing housing and the connecting frame.

8. The image forming apparatus according to claim 1, characterized in that the developing housing has a supported surface that extends along the direction of movement when the developing cartridge moves between the contact position and the separated position, and that contacts the support portion.

9. The support portion is a roller that is rotatable around a roller shaft extending in the axial direction, The image forming apparatus according to claim 8, characterized in that the roller rotates when the developing cartridge moves between the contact position and the separation position.

10. The drum unit has a second side frame located on the other side in the axial direction relative to the photosensitive drum, The developing cartridge has a coupling at its other axial end for inputting driving force to the developing roller. The developing housing is a cylindrical bearing on which the coupling is arranged, and has a bearing that protrudes in the axial direction. The image forming apparatus according to claim 1, further comprising a second spacer that, while sandwiched between the second side frame and the bearing, separates the developing roller from the photosensitive drum and separates the developing housing from the support portion.

11. The first side frame has a first surface located below the first spacer, The developing housing has a second surface located above the first surface, which sandwiches the first spacer between itself and the first surface. The image forming apparatus according to claim 1, characterized in that the maximum vertical length of the portion of the first spacer sandwiched between the first surface and the second surface is greater than the maximum vertical distance from the first surface to the second surface when the developing cartridge is in the contact position.

Images