Image forming apparatus

Abstract

To provide an image forming apparatus in which a drum cartridge can be easily attached to a main body casing.SOLUTION: An image forming apparatus includes a main body casing 2, a drum cartridge, and a developing cartridge. The main body casing 2 has a slot 22B extending in a first direction from an opening 22A toward an inside of the main body casing 2. The drum cartridge and the developing cartridge can be attached to the slot 22B through the opening in the first direction. The main body casing 2 includes a drum guide groove 24 extending in the first direction to guide movement of the drum cartridge. The drum cartridge includes a drum protrusion extending in the first direction to engage with the drum guide groove. The width of the drum guide groove 24 in the second direction decreases toward the inside of the main body casing 2 from the opening 22A. The width of the drum protrusion in the second direction decreases toward the inside of the main body casing 2 from the opening 22A in a state where the drum cartridge is attached to the slot 22B.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an image forming apparatus including a drum cartridge and a developing cartridge that are detachable from a main body housing. [Background technology]

[0002] Conventionally, there is known an image forming apparatus in which a drum cartridge and a developing cartridge can be separately attached to and detached from a main body housing (see Patent Document 1). In this technology, the drum cartridge and the developing cartridge are detachable in the axial direction of the photosensitive drum. The main body housing has an opening that allows the drum cartridge and the developing cartridge to be inserted, and a slot in which the drum cartridge and the developing cartridge are attached. The slot also includes a guide portion that guides the drum cartridge when it is being installed or removed, and a guide portion that guides the developing cartridge when it is being installed or removed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-173805 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration disclosed in Patent Document 1, the drum cartridge and developing cartridge are each attached to a slot, so compared to a configuration in which a process cartridge incorporating a drum cartridge and developing cartridge is attached to a slot in the main housing, the number of guide parts increases and the width of each guide part and the spacing between adjacent guide parts is narrower. In such a configuration, it becomes difficult for the user to install the drum cartridge and the developing cartridge into the slots in the main body housing.

[0005] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS An object of the present invention is to provide an image forming apparatus in which a drum cartridge can be easily attached to a main body housing even when the width of a guide portion is narrowed. [Means for solving the problem]

[0006] In order to solve the above problem, the image forming apparatus according to the present invention includes a main body housing having an opening and a slot extending from the opening in a first direction toward the inside of the main body housing, a drum cartridge having a photosensitive drum rotatable about a first axis extending in the first direction and mountable in the slot via the opening in the first direction, and a developing cartridge having a developing roller rotatable about a second axis extending in the first direction and mountable in the slot via the opening in the first direction. The developing cartridge is aligned with the drum cartridge in a second direction intersecting the first direction when the drum cartridge and the developing cartridge are mounted in the slot. The main body housing has a drum guide groove or a drum guide protrusion extending in the first direction for guiding the drum cartridge. The drum cartridge has a drum protrusion that extends in the first direction and fits into the drum guide groove, or a drum groove that extends in the first direction and into which the drum guide protrusion fits. When the main body housing has the drum guide groove, the width of the drum guide groove in the second direction narrows as it moves from the opening toward the inside of the main body housing, or the width of the drum protrusion in the second direction narrows as it moves from the opening toward the inside of the main body housing when the drum cartridge is attached to the slot. When the main body housing has the drum guide protrusion, the width of the drum guide protrusion in the second direction becomes wider as it moves from the opening toward the inside of the main body housing, or the width of the drum groove in the second direction becomes wider as it moves from the opening toward the inside of the main body housing when the drum cartridge is attached to the slot.

[0007] According to this configuration, when the main body housing has a drum guide groove, the drum cartridge has a drum protrusion that fits into the drum guide groove, and when the drum cartridge is attached to the slot, the width of the drum protrusion in the second direction at the tip (end farther from the opening) in the attachment direction is approximately equal to the minimum width of the drum guide groove in the second direction. The width of the drum guide groove in the second direction narrows from the opening toward the inside of the main body housing, or the width of the drum protrusion in the second direction narrows from the opening toward the inside of the main body housing. Furthermore, when the main body housing has a drum guide protrusion, the drum cartridge has a drum groove into which the drum guide protrusion fits, and when the drum cartridge is attached to the slot, the width of the drum groove in the second direction at the leading end in the attachment direction is substantially equal to the maximum width of the drum guide protrusion in the second direction. The width of the drum guide protrusion in the second direction becomes wider from the opening toward the inside of the main body housing, or the width of the drum groove in the second direction becomes wider from the opening toward the inside of the main body housing. In this way, the width of the opening side of the drum guide groove is larger than the width of the leading end side of the drum protrusion in the installation direction, making it easier to install the drum cartridge in the slot.Similarly, the width of the opening side of the drum guide protrusion is smaller than the width of the leading end side of the drum groove in the installation direction, making it easier to install the drum cartridge in the slot.

[0008] In the above-described image forming apparatus, the main body housing may have the drum guide groove, the drum cartridge may have the drum protrusion, and the width of the drum guide groove in the second direction may become narrower as it moves from the opening toward the inside of the main body housing. In this configuration, a width of the drum protrusion in the second direction may become narrower from the opening toward the inside of the main body housing when the drum cartridge is attached to the slot.

[0009] In the image forming apparatus, the drum guide groove may have a tapered shape. In this configuration, the drum protrusion may have a tapered shape.

[0010] According to this, the tapered shape allows the drum cartridge to be more smoothly mounted in the slot.

[0011] In the image forming apparatus, the main body housing may have a developer guide groove or a developer guide protrusion extending in the first direction for guiding the developer cartridge. The developer cartridge may have a developer protrusion that extends in the first direction and that fits into the developer guide groove, or a developer groove that extends in the first direction and into which the developer guide protrusion fits. When the main body housing has the developing guide groove, the width of the developing guide groove in the second direction narrows as it moves from the opening toward the inside of the main body housing, or the width of the developing protrusion in the second direction narrows as it moves from the opening toward the inside of the main body housing when the developing cartridge is attached to the slot. When the main body housing has the developing guide protrusion, the width of the developing guide protrusion in the second direction becomes wider as it moves from the opening toward the inside of the main body housing, or the width of the developing groove in the second direction becomes wider as it moves from the opening toward the inside of the main body housing when the developing cartridge is attached to the slot.

[0012] According to this configuration, when the main body housing has a developing guide groove, the drum cartridge has a developing protrusion that fits into the developing guide groove, and when the drum cartridge is attached to the slot, the width of the developing protrusion in the second direction is approximately equal to the minimum width of the developing guide groove in the second direction at the tip (end farther from the opening) in the attachment direction. The width of the developing guide groove in the second direction narrows from the opening toward the inside of the main body housing, or the width of the developing protrusion in the second direction narrows from the opening toward the inside of the main body housing. Furthermore, when the main body housing has a developing guide protrusion, the developing cartridge has a developing groove into which the developing guide protrusion fits, and when the developing cartridge is attached to the slot, the width of the developing groove in the second direction at the tip end in the attachment direction is substantially equal to the maximum width of the developing guide protrusion in the second direction. The width of the developing guide protrusion in the second direction becomes wider from the opening toward the inside of the main body housing, or the width of the developing groove in the second direction becomes wider from the opening toward the inside of the main body housing. In this way, the width of the opening side of the developer guide groove is larger than the width of the tip side of the developer protrusion in the installation direction, making it easier to install the developer cartridge in the slot. Similarly, the width of the opening side of the developer guide protrusion is smaller than the width of the tip side of the developer groove in the installation direction, making it easier to install the developer cartridge in the slot.

[0013] In the above-described image forming apparatus, the main body housing may have the developing guide protrusion, the developing cartridge may have the developing groove, and the width of the developing guide protrusion in the second direction may become wider as it moves from the opening toward the inside of the main body housing. In this configuration, a width of the developing groove in the second direction may become wider from the opening toward the inside of the main body housing when the developing cartridge is attached to the slot.

[0014] In the image forming apparatus, the developing guide projection may have a tapered shape. In this configuration, the development groove may have a tapered shape.

[0015] According to this, the tapered shape makes it possible to more smoothly mount the developing cartridge into the slot.

[0016] The image forming apparatus may further include an intermediate transfer belt that is located above the drum cartridge and the developing cartridge when the drum cartridge and the developing cartridge are attached to the main body housing. The main body may have a drum guide surface for guiding the drum cartridge, the drum guide surface being aligned with the drum guide groove or the drum guide protrusion in the second direction. The drum cartridge may have a drum contact surface that comes into contact with the drum guide surface when the drum cartridge is attached to the slot. The drum guide surface may be configured to approach the intermediate transfer belt as it moves from the opening toward the inside of the main body housing.

[0017] This increases the distance between the drum guide surface and the intermediate transfer belt on the opening side of the main body housing, so that when the drum cartridge is attached to the slot, it can be inserted from a position where the photosensitive drum is less likely to collide with the intermediate transfer belt.

[0018] In the image forming apparatus described above, the drum contact surface may be configured to approach the intermediate transfer belt as it moves from the opening toward the inside of the main body housing when the drum cartridge is attached to the slot.

[0019] In the image forming apparatus, the main body housing may have a developer guide surface for guiding the developer cartridge, the developer guide surface being aligned with the developer guide groove or the developer guide protrusion in the second direction. The developer cartridge may have a developer contact surface that comes into contact with the developer guide surface when the developer cartridge is attached to the slot. The developing guide surface may be configured to approach the intermediate transfer belt as it moves from the opening toward the inside of the main body housing.

[0020] This increases the distance between the developing guide surface and the intermediate transfer belt on the opening side of the main body housing, so that when the developing cartridge is attached to the slot, it can be inserted from a position where it is less likely to collide with the intermediate transfer belt.

[0021] In the image forming apparatus described above, the developing contact surface may be configured to approach the intermediate transfer belt as it moves from the opening toward the inside of the main body housing when the developing cartridge is attached to the main body housing.

[0022] In the image forming apparatus described above, the developing cartridge may include a first developing cartridge containing a developer of a first color, and a second developing cartridge containing a developer of a second color different from the first color. When the main body housing has the developing guide groove, the developing guide groove may include a first developing guide groove that guides the first developing cartridge and a second developing guide groove that guides the second developing cartridge, and the length of the first developing guide groove in the second direction may be different from the length of the second developing guide groove in the second direction. Also, when the main body housing has the developing guide protrusion, the developing guide protrusion may include a first developing guide protrusion that guides the first developing cartridge and a second developing guide protrusion that guides the second developing cartridge, and the length of the first developing guide protrusion in the second direction may be different from the length of the second developing guide protrusion in the second direction.

[0023] According to this, since the width in the second direction of the developing guide groove or the developing guide protrusion varies depending on the different colors of the developing cartridges, it is possible to prevent the developing cartridges from being inserted incorrectly.

[0024] In the image forming apparatus, the developing cartridge may include a first developing cartridge containing a developer of a first color and a second developing cartridge containing a developer of a second color different from the first color, and the drum cartridge may include a first drum cartridge corresponding to the first developing cartridge and a second drum cartridge corresponding to the second developing cartridge. When the main body housing has the drum guide groove, the drum guide groove may include a first drum guide groove that guides the first drum cartridge and a second drum guide groove that guides the second drum cartridge, and a length of the first drum guide groove in the second direction may be the same as a length of the second drum guide groove in the second direction. Furthermore, when the main body housing has the drum guide protrusion, the drum guide protrusion may include a first drum guide protrusion that guides the first drum cartridge and a second drum guide protrusion that guides the second drum cartridge, and the length of the first drum guide protrusion in the second direction may be the same as the length of the second drum guide protrusion in the second direction.

[0025] According to this, a common drum cartridge can be used corresponding to a plurality of developing cartridges, so that the manufacturing cost can be reduced.

[0026] In the above-described image forming apparatus, the main body housing may have a cover that opens and closes the opening, and a side wall that is positioned away from the cover in the first direction when the cover is in a closed position, and the side wall may have a first protrusion or a first long hole, and a second protrusion or a second long hole. The drum cartridge may be configured to have a drum long hole into which the first protrusion fits, or a drum protrusion that fits into the first long hole, when the drum cartridge is attached to the main housing, and the developer cartridge may be configured to have a developer long hole into which the second protrusion fits, or a developer protrusion that fits into the second long hole, when the developer cartridge is attached to the main housing.

[0027] According to this, the drum cartridge and the developing cartridge can be brought into contact with and separated from the intermediate transfer belt.

[0028] In the image forming apparatus, an intermediate transfer belt may be positioned above the drum cartridge and the developing cartridge when the drum cartridge and the developing cartridge are attached to the main body housing. In this configuration, a paper discharge unit may be located above the intermediate transfer belt. Effect of the Invention

[0029] According to the present invention, it is possible to provide an image forming apparatus in which a drum cartridge can be easily attached to a main body housing. [Brief description of the drawings]

[0030] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a color printer according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing a state in which the cover of the main body housing is opened and the drum cartridge and the developing cartridge are removed from the slots. [Diagram 3] 1A is a perspective view of a drum cartridge, FIG. 1B is a front view of the drum cartridge, and FIG. [Figure 4] 1A is a perspective view of the developing cartridge, FIG. 1B is a front view of the developing cartridge, and FIG. [Diagram 5]11 is an explanatory diagram illustrating the relationship between the drum guide groove and the developing guide protrusion of the slot, and the drum protrusion of the drum cartridge and the developing groove of the developing cartridge. FIG. [Figure 6] 5A and 5B are explanatory diagrams illustrating a state in which the drum cartridge is being mounted in a slot of the main body housing. [Figure 7] 11 is an explanatory diagram illustrating a state in which the developing cartridge is mounted in the slot of the main body housing. FIG. [Figure 8] 13 is an explanatory diagram according to a first modified example for explaining the relationship between a drum guide groove and a developing guide protrusion, and a drum protrusion and a developing groove. FIG. [Figure 9] These are explanatory diagrams explaining the relationship between the drum guide groove and the development guide protrusion, and the drum protrusion and the development groove, with (a) being an explanatory diagram relating to a second modified example, (b) being an explanatory diagram relating to a third modified example, and (c) being an explanatory diagram relating to a fourth modified example. [Figure 10] 13A and 13B are explanatory diagrams illustrating the relationship between the drum guide groove and the developing guide protrusion, and the drum protrusion and the developing groove, in which FIG. 13A is an explanatory diagram relating to a fifth modified example, and FIG. 13B is an explanatory diagram relating to a sixth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings as appropriate. In the following description, the overall configuration of a color printer 1 as an example of an image forming apparatus will first be described. In the following description, directions will be described in terms of the directions shown in Fig. 1. That is, the left side of Fig. 1 will be referred to as "front", the right side of Fig. 1 will be referred to as "rear", the front side of the paper in Fig. 1 will be referred to as "right", and the back side of the paper in Fig. 1 will be referred to as "left". Additionally, the top and bottom of Fig. 1 will be referred to as "top and bottom".

[0032] 1, color printer 1 includes a main body housing 2, a paper feed section 3, an image forming section 4, and a paper discharge section 5. The paper feed section 3 supplies paper P to the image forming section 4. The image forming section 4 forms an image on the paper P. The paper discharge section 5 discharges the paper P.

[0033] The paper feed unit 3 is located at the bottom inside the main body housing 2. The paper feed unit 3 includes a paper feed tray 31 and a paper feed mechanism 32. The paper feed tray 31 is detachable from the main body housing 2. The paper feed mechanism 32 transports paper P from the paper feed tray 31 to the image forming unit 4.

[0034] The image forming section 4 includes four drum cartridges 40, four developing cartridges 50, an exposure device SU, a transfer unit 60, and a fixing unit . The image forming section 4 includes four drum cartridges 40, four developing cartridges 50, an exposure device SU, and a transfer unit 60, which are arranged at an angle such that they are positioned downward from the front to the rear of the main body housing 2.

[0035] Each drum cartridge 40 has a photosensitive drum 41, a charger (not shown), and a drum frame PF. The photosensitive drum 41 is rotatable about a first axis X1 extending in a first direction. When attached to the main body housing 2, the four drum cartridges 40 are aligned in a second direction perpendicular to the first direction. In this embodiment, the image forming unit 4 includes four drum cartridges 40. The four drum cartridges 40 correspond to toners of the respective colors of black (K), yellow (Y), magenta (M), and cyan (C). The four drum cartridges 40 are arranged in the order of black (K), yellow (Y), magenta (M), and cyan (C) from the upstream side to the downstream side of the moving direction in which the surface of the intermediate transfer belt 63 that contacts each photosensitive drum 41 moves (from the front to the rear of the color printer 1). In the following description, when identifying a drum cartridge 40 corresponding to a toner color, the symbols K, Y, M, and C will be added after the reference symbol 40 to correspond to black, yellow, magenta, and cyan, respectively.

[0036] Each developer cartridge 50 has a developer roller 51 and a developer frame DF. The developer frame DF contains a developer. The developer roller 51 is rotatable about a second axis X2 extending in the first direction. The four developer cartridges 50 are aligned in the second direction when attached to the main body housing 2. When the four drum cartridges 40 and the four developer cartridges 50 are attached to the main body housing 2, the developer cartridges 50 are aligned with the respective drum cartridges 40 in the second direction. In this embodiment, the image forming unit 4 includes four developing cartridges 50. The four developing cartridges 50 correspond to toners of the respective colors of black (K), yellow (Y), magenta (M), and cyan (C). The four developing cartridges 50 are arranged in the order of black (K), yellow (Y), magenta (M), and cyan (C) from the upstream side to the downstream side of the moving direction in which the surface of the intermediate transfer belt 63 that contacts each photosensitive drum 41 moves (from the front to the rear of the color printer 1). In the following description, when identifying a developing cartridge 50 corresponding to a toner color, the symbols K, Y, M, and C will be added after the reference number 50 to correspond to black, yellow, magenta, and cyan, respectively.

[0037] The exposure device SU is located below each drum cartridge 40. The exposure device SU emits laser light to each photosensitive drum 41.

[0038] The transfer unit 60 is located between the four photosensitive drums 41 and the paper discharge tray 21. The transfer unit 60 includes a drive roller 61, a driven roller 62, an intermediate transfer belt 63, four primary transfer rollers 64, and a secondary transfer roller 65.

[0039] The intermediate transfer belt 63 is an endless belt. When the drum cartridge 40 and the developing cartridge 50 are attached to the main body casing 2, the intermediate transfer belt 63 is located above the drum cartridge 40 and the developing cartridge 50.

[0040] The primary transfer roller 64 is located inside the intermediate transfer belt 63. The primary transfer roller 64 and the photosensitive drum 41 sandwich the intermediate transfer belt 63 therebetween.

[0041] The secondary transfer roller 65 is located outside the intermediate transfer belt 63. The secondary transfer roller 65 and the drive roller 61 sandwich the intermediate transfer belt 63 therebetween.

[0042] The fixing unit 70 is located above the intermediate transfer belt 63. The fixing unit 70 includes a heating roller 71 and a pressure roller 72. The pressure roller 72 is pressed against the heating roller 71.

[0043] The paper discharge unit 5 is located at the top of the main body housing 2. The paper discharge unit 5 is located above the intermediate transfer belt 63. The paper discharge unit 5 includes a discharge roller 9 and a paper discharge tray 21. The discharge roller 9 transports the paper P toward the paper discharge tray 21.

[0044] In the color printer 1, first, a charger charges the surface of the photosensitive drum 41. Then, an exposure device SU exposes the surface of the photosensitive drum 41. As a result, an electrostatic latent image is formed on the photosensitive drum 41.

[0045] Next, the developing roller 51 supplies the developer to the electrostatic latent image on the photosensitive drum 41. As a result, a developer image is formed on the photosensitive drum 41. Then, the developer image on the photosensitive drum 41 is transferred onto the intermediate transfer belt 63.

[0046] When the paper P passes between the intermediate transfer belt 63 and the secondary transfer roller 65, the developer image on the intermediate transfer belt 63 is transferred onto the paper P. The developer image on the paper P is then fixed by the fixing unit 70. Next, the paper P is discharged to the paper discharge tray 21 by the discharge rollers 9.

[0047] As shown in FIG. 2, the main body housing 2 has an opening 22A, a slot 22B, and a cover C. The opening 22A allows each drum cartridge 40 and each developer cartridge 50 to pass through when the drum cartridge 40 and the developer cartridge 50 are attached or detached.

[0048] The slot 22B extends in a first direction from the opening 22A toward the inside of the main body housing 2. The slot 22B is a space for accommodating the four drum cartridges 40 and the four developing cartridges 50.

[0049] The cover C is a member for opening and closing the opening 22A. The cover C rotates about the lower end of the cover C. The cover C is movable between an open position (position shown in FIG. 2) where the opening 22A is opened and a closed position (not shown) where the opening 22A is closed. The cover C has a first projection C1 which fits into a drum slot 43 of each drum cartridge 40 (to be described later), and a second projection C2 which fits into a developer slot 53 of each developer cartridge 50 (to be described later).

[0050] The main body housing 2 has a first protrusion D1 and a second protrusion D2 on the inside of the side wall 2A. The first protrusion D1 fits into a drum elongated hole 43 (described later) of each drum cartridge 40. The second protrusion D2 fits into a developer elongated hole 53 (described later) of each developer cartridge 50. The side wall 2A is a side wall located away from the cover C in the first direction when the cover C is located in the closed position. The first protrusion D1 and the second protrusion D2 face the first protrusion C1 and the second protrusion C2 of the cover C in the first direction when the cover C is in the closed position. Furthermore, the main body housing 2 is provided with a cartridge guide portion 2B at the bottom of the slot 22B.

[0051] The cartridge guide portion 2B has a drum guide groove 24 and a developing guide protrusion 26. The drum guide groove 24 and the developing guide protrusion 26 are located on the upper surface of the cartridge guide portion 2B. Four drum guide grooves 24 and four developing guide protrusions 26 are lined up in the second direction (see also FIG. 5). Furthermore, the cartridge guide portion 2B has a through hole (not shown) through which the laser light from the exposure device SU passes. As shown in Fig. 5, each drum guide groove 24 extends in the first direction to guide the drum cartridge 40. The width of the drum guide groove 24 in the second direction narrows from the opening 22A toward the side wall 2A (i.e., the inside of the main body housing 2). More specifically, the drum guide groove 24 has a tapered shape in which the opposing side surfaces on both sides forming the groove are continuously inclined symmetrically. The four drum guide grooves 24K, 24Y, 24M, and 24C have the same shape. Each of the developer guide protrusions 26 extends in the first direction to guide the developer cartridge 50. The width of the developer guide protrusion 26 in the second direction becomes wider from the opening 22A toward the side wall 2A (i.e., the inside of the main body housing 2). More specifically, the developer guide protrusion 26 has a tapered shape in which the opposing side surfaces on both sides forming the protrusion are continuously inclined symmetrically. The four developer guide protrusions 26K, 26Y, 26M, and 26C have the same shape. As shown in FIG. 2, the upper surface of the cartridge guide portion 2B is inclined upward so as to approach the intermediate transfer belt 63 from the opening 22A toward the side wall 2A (ie, the inside of the main body housing 2).

[0052] As shown in FIG. 5, the upper surface of the cartridge guide portion 2B has a drum guide surface 25 and a developer guide surface 27. The drum guide surfaces 25 are located on both sides of the drum guide groove 24. The drum guide surfaces 25 are surfaces for guiding the drum cartridge 40, and are aligned with the drum guide groove 24 in the second direction. As described above, the upper surface of the cartridge guide portion 2B is inclined so as to approach the intermediate transfer belt 63. Therefore, the drum guide surface 25 is inclined so as to approach the intermediate transfer belt 63 as it moves from the opening 22A toward the inside of the main body housing 2. The developer guide surfaces 27 are located on both sides of the developer guide protrusion 26. The developer guide surfaces 27 are surfaces for guiding the developer cartridge 50, and are aligned with the developer guide protrusions 26 in the second direction. As described above, the upper surface of the cartridge guide portion 2B is inclined so as to approach the intermediate transfer belt 63. Therefore, the developing guide surface 27 is inclined so as to approach the intermediate transfer belt 63 as it moves from the opening 22A toward the inside of the main body housing 2. 6, the bottom surface 24A of the drum guide groove 24 is parallel to the lower surface of the intermediate transfer belt 63. On the other hand, the drum guide surface 25 is inclined with respect to the lower surface of the intermediate transfer belt 63. 7, the upper surface 26A of the developing guide protrusion 26 is parallel to the lower surface of the intermediate transfer belt 63. On the other hand, the developing guide surface 27 is inclined with respect to the lower surface of the intermediate transfer belt 63.

[0053] The drum cartridge 40 and the developing cartridge 50 are each independently attachable to and detachable from the main body casing 2 in a first direction. Specifically, each drum cartridge 40 can be installed in the slot 22B through the opening 22A in the first direction. Similarly, each developer cartridge 50 can be installed in the slot 22B through the opening 22A in the first direction. The four drum cartridges 40 have the same structure. The four developing cartridges 50 have the same structure.

[0054] As shown in FIG. 3, the drum frame PF of the drum cartridge 40 has a first drum side wall PF1 and a second drum side wall PF2 that face each other in a first direction, a corresponding third drum side wall PF3 and a fourth drum side wall PF4 in a second direction, and a fifth drum side wall PF5 that forms the bottom surface when the drum cartridge 40 is inserted in the slot 22B. The first drum side wall PF1 is a side wall located near the opening 22A when the drum cartridge 40 is attached to the slot 22B. The first drum side wall PF1 has a drum long hole 43 into which the first protrusion C1 of the cover C fits when the cover C is moved to the closed position. The second drum side wall PF2 is a side wall located far from the opening 22A when the drum cartridge 40 is attached to the main body housing 2. The second drum side wall PF2 has a drum elongated hole into which the first protrusion D1 of the main body housing 2 fits. This drum elongated hole has the same shape as the drum elongated hole 43, and is therefore not shown in the drawings. The first drum side wall PF1 and the second drum side wall PF2 support the photosensitive drum 41 so as to be rotatable. The third drum side wall PF3 and the fourth drum side wall PF4 connect the first drum side wall PF1 and the second drum side wall PF2, respectively.

[0055] The fifth drum side wall PF5 connects the first drum side wall PF1, the second drum side wall PF2, the third drum side wall PF3 and the fourth drum side wall PF4. The fifth drum side wall PF5 has a drum contact surface 45 that comes into contact with the drum guide surface 25 when the drum cartridge 40 is attached to the slot 22B. More specifically, when the drum cartridge 40 is attached to the slot 22B, the drum contact surface 45 is inclined so as to approach the intermediate transfer belt 63 as it moves from the opening 22A toward the inside of the main body housing 2 (see FIG. 6). The inclination angle of the drum contact surface 45 with respect to the first axis X1 of the photosensitive drum 41 is equal to the inclination angle of the drum guide surface 25 with respect to the lower surface of the intermediate transfer belt 63. Therefore, when the drum cartridge 40 is attached to the slot 22B, the drum guide surface 25 and the drum contact surface 45 come into contact with each other, and the photosensitive drum 41 and the intermediate transfer belt 63 are parallel to each other. The fifth drum side wall PF5 has a drum protrusion 46 protruding from the drum contact surface 45. The drum protrusion 46 extends in the first direction and is adapted to fit into the drum guide groove 24. The width of the drum protrusion 46 in the second direction narrows from the opening 22A toward the inside of the main body housing 2 when the drum cartridge 40 is attached to the slot 22B. More specifically, the drum protrusion 46 has a tapered shape in which the opposing side surfaces on both sides forming the protrusion are continuously inclined symmetrically. Both side surfaces of the drum protrusion 46 contact both side walls of the drum guide groove 24 when the drum cartridge 40 is attached to the slot 22B. 3, the lower surface of the drum protrusion 46 is parallel to the first axis X1 of the photosensitive drum 41, whereas the drum contact surface 45 is inclined with respect to the first axis X1 of the photosensitive drum 41. More specifically, the drum contact surface 45 is inclined upward from the opening 22A toward the inside of the main body housing 2 when the drum cartridge 40 is attached to the slot 22B.

[0056] As shown in FIG. 4, the developing frame DF of the developing cartridge 50 has a first developing side wall DF1 and a second developing side wall DF2 that face each other in a first direction, a third developing side wall DF3 and a fourth developing side wall DF4 that correspond in a second direction, and a fifth developing side wall DF5 that forms the bottom surface when the developing cartridge 50 is installed in the slot 22B. The first developing side wall DF1 is a side wall located near the opening 22A when the developing cartridge 50 is attached to the slot 22B. The first developing side wall DF1 has a developing slot 53 into which the second protrusion C2 of the cover C fits when the cover C is moved to the closed position. The second developer side wall DF2 is a side wall located far from the opening 22A when the developer cartridge 50 is attached to the slot 22B. The second developer side wall DF2 has a developer slot into which the second protrusion D2 of the main body housing 2 fits. This developer slot has the same shape as the developer slot 53, and is therefore not shown. The first developing sidewall DF1 and the second developing sidewall DF2 support the developing roller 51 so as to be rotatable. The third and fourth development sidewalls DF3 and DF4 connect the first and second development sidewalls DF1 and DF2, respectively.

[0057] The fifth development sidewall DF5 connects the first development sidewall DF1, the second development sidewall DF2, the third development sidewall DF3 and the fourth development sidewall DF4. The fifth developer side wall DF5 has a developer contact surface 55 that comes into contact with the developer guide surface 27 when the developer cartridge 50 is attached to the slot 22B. More specifically, when the developer cartridge 50 is attached to the main body housing 2, the developer contact surface 55 is inclined so as to approach the intermediate transfer belt 63 as it moves from the opening 22A toward the inside of the main body housing 2 (see FIG. 7). The inclination angle of the developer contact surface 55 with respect to the second axis X2 of the developer roller 51 is equal to the inclination angle of the developer guide surface 27 with respect to the lower surface of the intermediate transfer belt 63. Therefore, when the developer cartridge 50 is attached to the slot 22B, the developer guide surface 27 and the developer contact surface 55 come into contact with each other, and the developer roller 51 and the intermediate transfer belt 63 are parallel to each other. The fifth developing side wall DF5 also has a developing groove 56 on the developing contact surface 55. The developing groove 56 extends in the first direction and fits into the developing guide protrusion 26 when the developing cartridge 50 is attached to the slot 22B. The width of the developing groove 56 in the second direction becomes wider from the opening 22A toward the inside of the main body housing 2 when the developing cartridge 50 is attached to the slot 22B. More specifically, the developing groove 56 has a tapered shape in which the opposing side surfaces on both sides forming the groove are continuously inclined symmetrically. Both side surfaces of the developing groove 56 contact both side walls of the developing guide protrusion 26 when the developing cartridge 50 is attached to the slot 22B. 4, the upper surface of the developing groove 56 is parallel to the second axis X2 of the developing roller 51, whereas the developing contact surface 55 is inclined with respect to the second axis X2 of the developing roller 51. More specifically, the developing contact surface 55 is inclined upward from the opening 22A toward the inside of the main body housing 2 when the developing cartridge 50 is attached to the slot 22B.

[0058] Next, a procedure for mounting the drum cartridge 40 and the developing cartridge 50 in the slot 22B of the main body casing 2 will be described with reference to FIGS. 2 and 6, when the drum cartridge 40 is to be mounted in the slot 22B, the cover C is moved to the open position to expose the opening 22A and the slot 22B. Then, after the tip of the drum protrusion 46 is inserted into the drum guide groove 24 of the cartridge guide portion 2B, the drum cartridge 40 is inserted in the first direction as it is, so that the drum cartridge 40 is mounted in the main body housing 2. At this time, the width of the drum guide groove 24 on the opening 22A side is larger than the width of the tip side of the drum protrusion 46 in the mounting direction, so that the drum cartridge 40 can be easily mounted in the slot 22B. When the tip of the drum protrusion 46 is inserted into the drum guide groove 24, the drum contact surface 45 comes into contact with the drum guide surface 25. Then, when the drum cartridge 40 is inserted in the first direction, the tip of the drum protrusion 46 is guided by the drum guide groove 24, which gradually narrows in width, and the drum cartridge 40 is attached to a precise position within the main body housing 2.

[0059] According to this configuration, when the drum cartridge 40 is inserted into the drum guide groove 24 from the second drum side wall PF2 side, the narrow end of the drum protrusion 46 in the second direction is inserted first, and the wide end of the drum protrusion 46 is inserted last. Meanwhile, the drum guide groove 24 into which the drum protrusion 46 is fitted has a width in the second direction that is widest on the opening 22A side and narrowest on the side wall 2A side. Therefore, the drum cartridge 40 is easily attached to the main body housing 2 due to a large dimensional difference on the entrance (opening 22A) side. In addition, since the distance between the drum guide surface 25 and the intermediate transfer belt 63 is large on the entrance (opening 22A) side, it is possible to prevent the photosensitive drum 41 and the intermediate transfer belt 63 from coming into contact with each other and damaging the surface of the photosensitive drum 41 when the drum cartridge 40 is attached. In other words, when the drum cartridge 40 is attached to the slot 22B, the drum cartridge 40 can be inserted from a position where it is unlikely to collide with the intermediate transfer belt 63.

[0060] 2 and 7, when the developer cartridge 50 is to be mounted in the slot 22B, the cover C is moved to the open position to expose the opening 22A and the slot 22B. Then, after the tip of the developer groove 56 is inserted into the developer guide protrusion 26 of the cartridge guide portion 2B, the drum cartridge 40 is inserted in the first direction as it is, and the developer cartridge 50 is mounted in the main body housing 2. At this time, the width of the developer guide protrusion 26 on the opening 22A side is smaller than the width of the tip side of the developer groove 56 in the mounting direction, so that the developer cartridge 50 can be easily mounted in the slot 22B. When the tip of the developing groove 56 is inserted into the developing guide protrusion 26, the developing contact surface 55 comes into contact with the developing guide surface 27. Then, when the developing cartridge 50 is inserted in the first direction, the tip of the developing groove 56 is guided by the developing guide protrusion 26, which gradually becomes wider, and the developing cartridge 50 is attached to the correct position within the main body housing 2.

[0061] According to this configuration, by inserting the developing cartridge 50 into the drum guide groove 24 from the second developing sidewall DF2 side, the end of the developing groove 56 with a wider width in the second direction is inserted first, and the end of the developing groove 56 with a narrower width in the second direction is inserted last. Meanwhile, the developing guide protrusion 26 into which the developing groove 56 is fitted has a width in the second direction that is narrowest on the opening 22A side and widest on the sidewall 2A side. Therefore, the developing cartridge 50 is easily attached to the main housing 2 due to the large dimensional difference on the entrance (opening 22A) side. In addition, since the distance between the developing guide surface 27 and the intermediate transfer belt 63 is large on the entrance (opening 22A) side, it is possible to prevent the developing roller 51 and the intermediate transfer belt 63 from coming into contact with each other and damaging the surface of the developing roller 51 when the developing cartridge 50 is attached. In other words, when the developing cartridge 50 is attached to the slot 22B, the developing cartridge 50 can be inserted from a position where it is unlikely to collide with the intermediate transfer belt 63.

[0062] When the drum cartridge 40 is inserted into the slot 22B, the first protrusion D1 of the side wall 2A of the main body housing 2 fits into the elongated drum hole of the second drum side wall PF2 of the drum cartridge 40. When the developer cartridge 50 is attached to the slot 22B, the second protrusion D2 of the side wall 2A of the main body housing 2 fits into the developer slot of the second developer side wall DF2 of the developer cartridge 50. When the cover C is moved to the closed position, the first protrusion C1 of the cover C fits into the drum long hole 43 of the first drum side wall PF1 of the drum cartridge 40, and the second protrusion C2 of the cover C fits into the developer long hole 53 of the first developer side wall DF1 of the developer cartridge 50. In this state, when the drum pressing member 80 (see FIG. 1) is raised, the drum cartridge 40 is raised and the photosensitive drum 41 comes into contact with the intermediate transfer belt 63. When the developer pressing member (not shown) is raised, the developer cartridge 50 is raised and the developer roller 51 comes into contact with the photosensitive drum 41 at a predetermined position.

[0063] As described above, the following effects can be obtained in this embodiment. Since the width of the opening 22A side of the drum guide groove 24 is larger than the width of the tip side of the drum protrusion 46 in the mounting direction, the drum cartridge 40 can be easily mounted in the slot 22B.

[0064] Since the drum guide groove 24 of the main body housing 2 has a tapered shape and the corresponding drum protrusion 46 of the drum cartridge 40 also has a tapered shape, the drum cartridge 40 can be more smoothly attached to the slot 22B.

[0065] Since the width of the opening side 22A of the developer guide projection 26 is smaller than the width of the tip end side of the developer groove 56 in the mounting direction, the developer cartridge 50 can be easily mounted in the slot 22B.

[0066] Since the developing guide projection 26 of the main body housing 2 has a tapered shape and the corresponding developing groove 56 of the developing cartridge 50 also has a tapered shape, the developing cartridge 50 can be more smoothly attached to the slot 22B.

[0067] Since the distance between the drum guide surface 25 and the intermediate transfer belt 63 is large on the opening 22A side of the main body housing 2, when the drum cartridge 40 is mounted in the slot 22B, the drum cartridge 40 can be inserted from a position where the photosensitive drum 41 is unlikely to collide with the intermediate transfer belt 63.

[0068] Since the distance between the developing guide surface 27 and the intermediate transfer belt 63 is large on the opening 22A side of the main body housing 2, when the developing cartridge 50 is attached to the slot 22B, the developing cartridge 50 can be inserted from a position where it is unlikely to collide with the intermediate transfer belt 63.

[0069] The first protrusion D1 and the second protrusion D2 on the side wall 2A of the main body housing 2 fit into the drum long hole of the drum cartridge 40 and the developer long hole of the developer cartridge 50, respectively, so that the drum cartridge 40 and the developer cartridge 50 can be brought into contact with and separated from the intermediate transfer belt 63.

[0070] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. The specific configuration can be appropriately changed without departing from the spirit of the present invention.

[0071] In the above embodiment, the drum guide groove 24 and the developing guide projection 26 are located on the upper surface of the cartridge guide portion 2B, but the present invention is not limited to this configuration. For example, the main body housing 2 may have a drum guide protrusion instead of the drum guide groove 24, and a developer guide groove instead of the developer guide protrusion 26. In this case, the drum cartridge 40 has a drum groove that extends in the first direction and into which the drum guide protrusion fits when the drum cartridge 40 is attached to the slot 22B. Similarly, the developer cartridge 50 has a developer protrusion that extends in the first direction and fits into the developer guide groove when the developer cartridge 50 is attached to the slot 22B. When the main body housing 2 has a drum guide protrusion, the width of the drum guide protrusion in the second direction becomes wider from the opening 22A toward the inside of the main body housing 2. In addition, the width of the drum groove of the drum cartridge 40 in the second direction becomes wider from the opening 22A toward the inside of the main body housing 2 when the drum cartridge 40 is attached to the slot 22B. Furthermore, when the main body housing 2 has a developing guide groove, the width of the developing guide groove in the second direction narrows from the opening 22A toward the inside of the main body housing 2. In addition, the width of the developing protrusion of the developing cartridge 50 in the second direction narrows from the opening 22A toward the inside of the main body housing 2 when the developing cartridge 50 is attached to the slot 22B.

[0072] Furthermore, the main housing 2 may have a drum guide groove and a developer guide groove, the drum cartridge 40 may have a drum protrusion, and the developer cartridge 50 may have a developer protrusion. Similarly, the main body 2 may have a drum guide protrusion and a developer guide protrusion, the drum cartridge 40 may have a drum groove, and the developer cartridge 50 may have a developer groove. Furthermore, the main body housing 2 may have a drum guide groove and a drum guide protrusion, and a developing guide groove and a developing guide protrusion.

[0073] In the above embodiment, the drum guide surface 25 and the development guide surface 27 on the upper surface of the cartridge guide portion 2B were inclined so as to approach the intermediate transfer belt 63 as they proceed from the opening 22A toward the inside of the main body housing 2, but the present invention is not limited to such a configuration. The drum guide surface 25 and the developer guide surface 27 may also be configured not to be inclined so as to approach the intermediate transfer belt 63 as they move from the opening 22A toward the inside of the main body housing 2. For example, the drum guide surface 25 and the developer guide surface 27 may also be configured to be parallel to the lower surface of the intermediate transfer belt 63. In this case, the drum contact surface 45 of the drum cartridge 40 is parallel to the first axis X1 of the photosensitive drum 41, and the developer contact surface 55 of the developer cartridge 50 is parallel to the second axis X2 of the developer roller 51.

[0074] In the above embodiment, the side wall 2A of the main body housing 2 has the first protrusion D1 and the second protrusion D2, and the cover C has the first protrusion C1 and the second protrusion C2, but the present invention is not limited to such a configuration. For example, the side wall 2A of the main body housing 2 may have a first oblong hole instead of the first protrusion D1, and a second oblong hole instead of the second protrusion D2. In this case, the drum cartridge 40 has a drum protrusion that fits into the first oblong hole when the drum cartridge 40 is attached to the main body housing 2. Similarly, the developer cartridge 50 has a developer protrusion that fits into the second oblong hole when the developer cartridge 50 is attached to the main body housing 2. Similarly, the first protrusion C1 and the first oblong hole, and the second protrusion C2 and the second oblong hole may be interchanged for the cover C. In this case, the drum cartridge 40 has a drum protrusion, and the developer cartridge 50 has a developer protrusion. Also, different combinations may be used on the entrance (opening 22A) side and the back (side wall 2A) side.

[0075] In the embodiment described above, the four drum guide grooves 24 of the main body housing 2 have the same shape, and the four developer guide protrusions 26 have the same shape. Also, the four drum cartridges 40 and the four developer cartridges 50 each have the same shape. However, the present invention is not limited to this configuration. For example, the developer cartridge 50 may include four developer cartridges, each having a different width of developer grooves or developer protrusions, while the drum cartridge 40 may include four drum cartridges, each having the same width of drum protrusions or drum grooves.

[0076] More specifically, as shown in the first modified example of Fig. 8, the developing cartridge 50 includes four developing cartridges 50K, 50Y, 50M, and 50C. Of these, for example, the black developing cartridge 50K is a first developing cartridge that contains a first color developer. The other developing cartridges 50Y, 50M, and 50C are second developing cartridges that contain a second color developer different from the first color. 8, the width of the developing groove 56 of the developing cartridge 50K is wider than the widths of the developing groove 56 of the developing cartridge 50Y, the developing groove 56 of the developing cartridge 50M, and the developing groove 56 of the developing cartridge 50C. In particular, the width of the leading end side in the mounting direction of the developing cartridge 50K is wider than the widths of the leading ends in the mounting direction of the other developing cartridges 50Y, 50M, and 50C. The widths of the developing grooves 56 of the developing cartridges 50Y, 50M, and 50C may be different for each toner color.

[0077] Meanwhile, the drum cartridge 40 includes four drum cartridges 40K, 40Y, 40M, and 40C. Of these, the black drum cartridge 40K is a first drum cartridge corresponding to the first developing cartridge, and the other drum cartridges 40Y, 40M, and 40C are second drum cartridges corresponding to the second developing cartridge. Regardless of the color of the toner, the length (width) of the drum protrusion 46 of the drum cartridge 40 in the second direction is the same for all of them. More specifically, the widths of the leading ends of the developing cartridges 50K, 50Y, 50M, and 50C in the mounting direction are all the same.

[0078] The main body housing 2 has, on the upper surface of the cartridge guide portion 2B, a first drum guide groove 24K for guiding the black drum cartridge 40K, a second drum guide groove 24Y for guiding the yellow drum cartridge 40Y, a second drum guide groove 24M for guiding the magenta drum cartridge 40M, and a second drum guide groove 24C for guiding the cyan drum cartridge 40C. The length of the first drum guide groove 24K in the second direction is the same as the lengths of the second drum guide grooves 24Y, 24M, and 24C in the second direction. In more detail, the first drum guide groove 24K and the second drum guide grooves 24Y, 24M, and 24C all have the same width on the opening 22A side. In addition, the main body housing 2 has, on the upper surface of the cartridge guide portion 2B, a first developing guide protrusion 26K for guiding the black developing cartridge 50K, a second developing guide protrusion 26Y for guiding the yellow developing cartridge 50Y, a second developing guide protrusion 26M for guiding the magenta developing cartridge 50M, and a second developing guide protrusion 26C for guiding the cyan developing cartridge 50C. The widths of the first developing guide protrusion 26K and the second developing guide protrusions 26Y, 26M, and 26C are different in accordance with the width of the developing groove 56 of each developing cartridge 50. That is, the length of the first developing guide protrusion 26K in the second direction is different from the length of the second developing guide protrusions 26Y, 26M, and 26C in the second direction. In detail, the width of the first developing guide protrusion 26K on the opening 22A side is wider than the width of the second developing guide protrusions 26Y, 26M, and 26C on the opening 22A side.

[0079] According to the configuration of the first modified example described above, the width of the developing groove 56 in the second direction differs depending on the different colors of the developing cartridges 50, so that it is possible to prevent the developing cartridges 50 from being inserted incorrectly. Furthermore, since a common drum cartridge 40 can be used corresponding to a plurality of developing cartridges 50, manufacturing costs can be reduced.

[0080] In the configuration of the first modified example described above, the main body housing 2 may have a first drum guide protrusion and a second drum guide protrusion instead of the first drum guide groove 24K and the second drum guide grooves 24Y, 24M, and 24C. Also, the main body housing 2 may have a first developing guide groove and a second developing guide groove instead of the first developing guide protrusion 26K and the second developing guide protrusions 26Y, 26M, and 26C. In this case, the first drum cartridge 40K, when attached to the slot 22B, has a first drum groove that extends in the first direction and into which the first drum guide protrusion fits, and the second drum cartridges 40Y, 40M, 40C, when attached to the slot 22B, have second drum grooves that extend in the first direction and into which the second drum guide protrusion fits. Similarly, the first developer cartridge 50K has a first developer protrusion that extends in a first direction and fits into the first developer guide groove when installed in slot 22B, and the second developer cartridges 50Y, 50M, 50 have a second developer protrusion that extends in the first direction and fits into the second developer guide groove when installed in slot 22B. The length of the first drum guide protrusion in the second direction is the same as the length of the second drum guide protrusion in the second direction. Also, the length of the first developing guide groove in the second direction is different from the length of the second developing guide groove in the second direction.

[0081] The second to sixth modified examples will be described below with reference to Figures 9 and 10. In the following description, the same components as those in the above embodiment are given the same reference numerals, and detailed description thereof will be omitted.

[0082] As shown in FIG. 9(a), in the configuration of the second modified example, the main body housing 2 has a drum guide groove 124 and a developing device guide protrusion 126 on the upper surface of the cartridge guide portion 2B. The width of the drum guide groove 124 in the second direction tapers toward the inside of the main body housing 2 from the opening 22A to partway toward the side wall 2A, and then has a constant width. The width of the developing guide protrusion 126 in the second direction tapers toward the inside of the main body housing 2 from the opening 22A to partway toward the side wall 2A, and then has a constant width. The drum cartridge 40 has a drum protrusion 146 that corresponds to the shape of the drum guide groove 124. The developer cartridge 50 has a developer groove 156 that corresponds to the shape of the developer guide protrusion 126. Even with this configuration, the drum cartridge 40 and the developing cartridge 50 can be easily attached to the main housing 2 due to the large dimensional difference on the inlet (opening 22A) side.

[0083] As shown in FIG. 9(b), in the configuration of the third modified example, the main body housing 2 has a drum guide groove 124 and a developing guide protrusion 126 similar to those in the second modified example. On the other hand, the drum protrusion 246 of the drum cartridge 40 has a constant width corresponding to the width of the straight portion of the drum guide groove 124. The developing groove 256 of the developing cartridge 50 has a constant width corresponding to the width of the straight portion of the developing guide protrusion 126. Even with this configuration, the drum cartridge 40 and the developing cartridge 50 can be easily attached to the main body housing 2 due to the large dimensional difference on the entrance side.

[0084] As shown in FIG. 9(c), in the configuration of the fourth modified example, the main body housing 2 has a drum guide groove 324 and a developing device guide protrusion 326 on the upper surface of the cartridge guide portion 2B. The width of the drum guide groove 324 in the second direction narrows in a stepped manner from the opening 22A to the side wall 2A toward the inside of the main body housing 2. The width of the developing guide protrusion 326 in the second direction becomes wider in a stepped manner from the opening 22A to the side wall 2A toward the inside of the main body housing 2. The drum cartridge 40 has a drum protrusion 346 that corresponds to the shape of the drum guide groove 324. The developer cartridge 50 has a developer groove 356 that corresponds to the shape of the developer guide protrusion 326. Even with this configuration, the drum cartridge 40 and the developing cartridge 50 can be easily attached to the main body housing 2 due to the large dimensional difference on the entrance side.

[0085] As shown in FIG. 10(a), in the configuration of the fifth modified example, the main body housing 2 has a drum guide groove 424 and a developing device guide protrusion 426 on the upper surface of the cartridge guide portion 2B. The width of the drum guide groove 424 in the second direction is constant from the opening 22A to the side wall 2A. Similarly, the width of the developing guide protrusion 426 in the second direction is constant from the opening 22A to the side wall 2A. In the drum cartridge 40, the width of the drum protrusion 446 in the second direction has a constant width corresponding to the width of the drum guide groove 424 from the opening 22A to partway toward the side wall 2A, and then tapers toward the side wall 2A. In the developing cartridge 50, the width of the developing groove 456 in the second direction has a constant width corresponding to the width of the developing guide protrusion 426 from the opening 22A to partway toward the side wall 2A, and then tapers toward the side wall 2A. Even with this configuration, the drum cartridge 40 and the developing cartridge 50 can be easily attached to the main body housing 2 due to the large dimensional difference on the entrance side.

[0086] As shown in FIG. 10(b), in the configuration of the sixth modified example, the main body housing 2 has a drum guide groove 524 and a developing guide protrusion 526 on the upper surface of the cartridge guide portion 2B. The width of the drum guide groove 524 in the second direction tapers from the opening 22A and the side wall 2A toward the inside of the main body housing 2, and has a constant width in the central portion. On the other hand, the width of the developing guide protrusion 526 in the second direction is constant from the opening 22A to the side wall 2A. The drum protrusion 546 of the drum cartridge 40 has a constant width from the opening 22A to the side wall 2A. The developing groove 556 of the developing cartridge 50 tapers from the opening 22A and the side wall 2A toward the inside of the main body housing 2, and has a constant width in the central portion corresponding to the width of the developing guide protrusion 526. Even with this configuration, the drum cartridge 40 and the developing cartridge 50 can be easily attached to the main body housing 2 due to the large dimensional difference on the entrance side.

[0087] In the above embodiment and each modified example, the present invention is applied to a color printer 1, but the present invention is not limited to this and may be applied to other image forming devices, such as monochrome printers, copiers, and multifunction devices.

[0088] The elements described in the above-mentioned embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0089] 1. Color printer 2 Main unit 22A opening 22B Slot 24 Drum guide groove 26 Development guide protrusion 40 Drum Cartridge 41 Photosensitive drum 46 Drum protrusion 50 Developing Cartridge 51 Developing roller 56 Development groove

Claims

1. a main body housing having an opening; a drum cartridge having a photosensitive drum rotatable about an axis extending in a first direction, the drum cartridge being removably insertable into the main body housing through the opening in the first direction; a developer cartridge having a developer roller, the developer cartridge being removably insertable into the main body housing through the opening in the first direction; When the drum cartridge and the developing cartridge are attached to the main body housing, the photosensitive drum and the developing roller are arranged side by side in a second direction intersecting the first direction, An image forming apparatus characterized in that the main body housing has a drum guide groove extending in the first direction for guiding the movement of the drum cartridge, the drum guide groove having a first inclined surface, and the first inclined surface inclined in the second direction away from the developing roller as it moves toward the inside of the main body housing.

2. The image forming device described in Claim 1, characterized in that the drum cartridge has a second inclined surface in the portion guided by the drum guide groove, and the second inclined surface inclines in the second direction away from the developing roller as it moves toward the inside of the main body housing when the drum cartridge is attached to the main body housing.

3. An image forming device as described in claim 1 or claim 2, characterized in that the drum guide groove has a shape that narrows in width as it approaches the inside of the main body housing.

4. An image forming device described in any one of claims 1 to 3, characterized in that the drum guide groove has a surface that connects to the first inclined surface and extends along the first direction, further inside the main body housing than the first inclined surface.

5. An image forming device as described in any one of claims 1 to 4, characterized in that the drum guide groove has a first opposing surface facing the first inclined surface, and the first inclined surface and the first opposing surface have a tapered shape in which the distance between them becomes smaller as they approach the inside of the main body housing.

6. The drum cartridge has a first drum side wall and a second drum side wall that faces the first drum side wall in the first direction when the drum cartridge is attached to the main body housing, and the second drum side wall is farther from the opening than the first drum side wall, 6. The image forming apparatus according to claim 1, wherein the drum cartridge has a drum protrusion that fits into the drum guide groove, and the drum protrusion has a tapered shape that narrows as it moves from the first drum side wall to the second drum side wall.

7. The developing cartridge has a first developing side wall and a second developing side wall that faces the first developing side wall in the first direction when the developing cartridge is attached to the main body housing, one of the inner surface of the main body housing and the second developing side wall of the developing cartridge has a second hole; An image forming apparatus as described in any one of claims 1 to 6, characterized in that the other of the inner surface of the main body housing and the second developing side wall of the developing cartridge has a second protrusion that engages with the second hole when the developing cartridge is attached to the main body housing.

8. The second developing side wall of the developing cartridge has the second hole, 8. The image forming apparatus according to claim 7, wherein the inner surface of the main body housing has the second protrusion.

9. The main body housing has a developing guide groove for guiding the movement of the developing cartridge, 9. The image forming apparatus according to claim 1, wherein the developing guide groove extends in the first direction.

10. An image forming apparatus as described in Claim 9, characterized in that the development guide groove has a tapered shape.

11. An image forming apparatus as described in any one of claims 1 to 10, characterized in that the drum cartridge can be removed separately from the developing cartridge.

12. An image forming device described in any one of claims 1 to 11, characterized in that when the drum cartridge and the developer cartridge are attached to the main body housing, it further comprises an intermediate transfer belt positioned above the drum cartridge and the developer cartridge.

13. An image forming apparatus as described in Claim 12, further comprising a paper discharge unit including a paper discharge roller configured to transport a sheet, the paper discharge unit being located above the intermediate transfer belt.

Images