JP2012118176A - Process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process cartridge that can secure a stable contact state of a developing roller with a photosensitive drum and attain excellent contact/separation of the developing roller with/from the photosensitive drum.SOLUTION: A process cartridge 3 comprises: a drum cartridge 7 including a photosensitive drum 5 on which an electrostatic latent image is formed and drum bearings 31 and 32 for rotatably supporting axial end parts of the photosensitive drum 5, respectively; and a developing cartridge 9 which includes a developing roller 8 and is attachably/detachably mounted on the drum cartridge 7. The developing roller 8 is movable between a contact position at which the roller comes into contact with the photosensitive drum 5 and a spaced position at which the roller is spaced from the photosensitive drum 5, in a state in which the developing cartridge 9 is mounted on the drum cartridge 7. The drum bearings 31 and 32 include support parts 61 and 68 for supporting axial end parts of the developing roller 8 moving between the contact position and the spaced position, respectively.

Description

The present invention relates to a process cartridge that can be attached to and detached from an image forming apparatus such as an electrophotographic printer.

Conventionally, an electrophotographic printer in which a process cartridge is detachably mounted is known. The process cartridge includes a developing cartridge having a developing roller, and a drum cartridge having the developing cartridge detachably mounted thereon and having a photosensitive drum.

  In this type of process cartridge, when the developing cartridge is mounted on the drum frame of the drum cartridge, the developing roller provided in the developing cartridge faces the photosensitive drum provided in the drum cartridge. In the process cartridge having such a configuration, in order to suppress toner deterioration, with the developing cartridge mounted on the drum cartridge, the developing roller is brought into contact with the photosensitive drum only during image formation. The developing roller is separated from the drum. With this contact and separation, the end of the developing roller slides on the drum frame (see Patent Document 1).

JP 2009-162912 A

However, in the conventional process cartridge as seen in Patent Document 1,
When the developing roller comes into contact with or separates from the photosensitive drum, the end of the developing roller slides on the drum frame, and the end of the developing roller and the drum frame rub against each other. The edge part shifted | deviated and the contact state of the photosensitive drum and the developing roller was unstable. If the contact state between the photosensitive drum and the developing roller is unstable, a good image may not be formed.

  An object of the present invention is to provide a process cartridge capable of ensuring a stable contact state of a developing roller with respect to a photosensitive drum and achieving good contact and separation of the developing roller with respect to the photosensitive drum.

  In order to achieve this object, a process cartridge according to claim 1 comprises a photosensitive drum on which an electrostatic latent image is formed, a frame in which the photosensitive drum is accommodated and a developing cartridge accommodating portion, and the frame. A drum cartridge that rotatably supports an axial end portion of the photosensitive drum, and a developing cartridge that has a developing roller and is detachably mounted in the developing cartridge housing portion. The developing roller is movable between a contact position in contact with the photosensitive drum and a separated position separated from the photosensitive drum in a state where the developing cartridge is mounted on the drum cartridge, and the drum bearing is A support portion for supporting the end portion in the axial direction of the developing roller that moves between the contact position and the separation position. And wherein the Rukoto.

  The frame of the process cartridge according to claim 2, further comprising: a first guide portion that guides the developing roller when the developing cartridge is mounted on the drum cartridge, and the support portion is the first guide. And a second guide portion that is disposed downstream of the developing cartridge in the mounting direction of the developer cartridge and guides the developing roller continuously with the first guide portion.

  Further, the end portion of the developing roller of the process cartridge according to claim 3 is in contact with the second guide portion at the separated position.

  According to a fourth aspect of the present invention, the developing roller of the process cartridge has a rotation shaft, and the support portion supports a color member that covers an end portion of the rotation shaft in the axial direction.

  Further, the drum bearing of the process cartridge according to claim 5 is made of a material having a higher slidability than a material of the frame.

  In the first aspect of the invention, the drum bearing supports the end portion of the developing roller that moves between the contact position and the separated position, so that the end portion of the developing roller moves as compared to when the drum frame moves. Since the friction at the end of the developing roller is reduced, the contact state between the photosensitive drum and the developing roller is stabilized, and good image formation is possible.

  According to the second aspect of the present invention, since the first guide portion and the second guide portion are continuous, the end portion of the developer cartridge is guided when the developer cartridge is attached to the drum cartridge. Can be mounted on a drum cartridge.

  In the third aspect of the invention, the end of the developing roller is in contact with the second guide portion at the separated position, so that the developing roller can smoothly move from the separated position to the contact position.

  According to the fourth aspect of the present invention, since the end of the rotation shaft is covered with the color member, the rotation shaft rotates in the color member, so that the end of the developing roller and the drum are not covered with the color member. The frictional resistance with the bearing can be reduced.

  According to the fifth aspect of the present invention, the drum bearing is made of a material having higher slidability than the material of the drum frame, so that the friction between the end of the developing roller and the drum bearing can be further reduced.

1 is a side sectional view showing an embodiment of a printer as an example of an image forming apparatus of the present invention. It is a perspective view from the right front direction of a process cartridge. It is a left view of a process cartridge. It is a top view of a process cartridge. It is a perspective view from the right front direction of a drum cartridge. It is a perspective view of a drum left bearing. It is a side view of a drum left bearing. It is a figure showing mounting | wearing of the drum left bearing. It is a figure showing mounting | wearing of the drum left bearing. It is a perspective view of a drum right bearing. It is a perspective view of a drum right bearing. It is a figure showing mounting | wearing of the drum right bearing. It is a figure showing mounting | wearing of the drum right bearing. It is a figure explaining the state which the developing roller is pressing on the photosensitive drum. FIG. 4 is a diagram illustrating a state where a developing roller is separated from a photosensitive drum.

1. Overall Configuration of Printer The printer 1 is a tandem type color printer. In the main body casing 2 of the apparatus main body, four process cartridges 3 are arranged in parallel corresponding to the respective colors of black, yellow, magenta and cyan. Each process cartridge 3 can be attached to and detached from the main body casing 2 with the top cover 4 on the upper surface of the main body casing 2 being opened.

Each process cartridge 3 includes a drum cartridge 7 that holds the photosensitive drum 5 and the scorotron charger 6, and a developing cartridge 9 that holds the developing roller 8 and is detachably attached to the drum cartridge 7. The surface of the photosensitive drum 5 is uniformly charged by the scorotron charger 6 and then selectively exposed by the LEDs provided in the LED unit 10. Thereby, an electrostatic latent image based on the image data is formed on the surface of each photosensitive drum 5. Each electrostatic latent image is visualized by toner carried on the developing roller 8,
A toner image is formed on the surface of the photosensitive drum 5.

The paper P is accommodated in a paper feed cassette 11 disposed at the bottom of the main casing 2.
The paper P stored in the paper feed cassette 11 is transported onto the transport belt 12 by various rollers. The conveyor belt 12 is disposed to face the four photosensitive drums 5 from below.
The paper P transported on the transport belt 12 is transported by the travel of the transport belt 12.
And each photosensitive drum 5 sequentially. Then, the toner image on the surface of the photosensitive drum 5 is transferred to the paper P by the transfer bias applied to the transfer roller 13 when facing the paper P.
Transcribed above. The transfer roller 13 is disposed to face each photosensitive drum 5 with the conveyance belt 12 interposed therebetween.

The sheet P on which the toner image is transferred is conveyed to the fixing unit 14. The toner image transferred onto the paper P is thermally fixed by the fixing unit 14. Thereafter, the paper P is discharged to the paper discharge tray 15 by various rollers.

In the case of distinguishing the process cartridge 3 from a specific color from other colors, K (black), Y (yellow), M (representing each color at the end of the reference numerals thereof.
Magenta) and C (cyan).

Further, the upstream side in the conveyance direction of the paper P by the conveyance belt 12 is the front side in the printer 1, and the time when the printer 1 is viewed from the front side is the left and right reference in the printer 1. With respect to the process cartridge 3, the side where the developing cartridge 9 is disposed with respect to the photosensitive drum 5 in the state of being placed in the horizontal direction is the front side, and the time when the process cartridge 3 is viewed from the front side is the upper, lower, left and right reference. . Each figure includes arrows indicating front, rear, up, down, left and right directions.

2. Process Cartridge The process cartridge 3 includes a developing cartridge 9 and a drum cartridge 7.

(1) Developer Cartridge As shown in FIGS. 2 to 5, the developer cartridge 9 is detachably disposed with respect to the developer cartridge housing 16 described later. The developing cartridge 9 includes a housing 17, a developing roller 8, a supply roller 18, a layer thickness regulating blade 19, an agitator 20, and a separation portion 21.

  The casing 17 is formed in a box shape whose rear side is opened, and contains toner.

The developing roller 8, the supply roller 18, the layer thickness regulating blade 19, and the agitator 20 are held in the housing 17. (See Figure 1)
The spacing portion 21 protrudes outward in the left-right direction from the housing 17 and has a substantially cylindrical shape.

  As shown in FIG. 4, the developing roller 8 is disposed so as to be exposed rearward from the housing 17, and is rotatably supported on both side walls 22 and 23 of the housing 17. The developing roller 8 includes a metal developing roller shaft 24 as an example of a rotating shaft, a rubber roller 25 made of conductive rubber covering the developing roller shaft 24, and both ends of the developing roller shaft 24 rotatably inserted. Color members 26 and 27 are provided. The collar members 26 and 27 are disposed at positions facing each other in the left-right direction so as to protrude outward from the rear ends of the side walls 22 and 23, respectively. The collar members 26 and 27 are rotatably supported by the side walls 22 and 23.

  Further, the developing cartridge 9 includes a developing passive gear 28 to which driving force such as the developing roller 8 is input. As shown in FIG. 3, the development passive gear 28 is disposed in front of the collar member 26 on the left side wall 22 of the housing 17. The developing passive gear 28 faces a long hole 49 formed in a drum side wall 35 of the drum cartridge 7 described later in a state where the developing cartridge 9 is mounted on the drum cartridge 7. The developing passive gear 28 receives the rotational force in the clockwise direction in FIG.

(2) Drum Cartridge The drum cartridge 7 includes a drum frame 29, the photosensitive drum 5, a flange member 30, a drum left bearing 31, a drum right bearing 32, a connecting member 33, and a pressing member 34. .

  As shown in FIG. 5, the drum frame 29 is made of PS (polystyrene) and integrally includes a pair of drum side walls 35 and 36, a drum rear wall 37, a drum upper wall 38, and a drum front wall 39. Yes.

  The pair of drum side walls 35 and 36 are opposed to each other with a space in the left-right direction.

  The left drum side wall 35 includes a left side wall rear portion 40, a left side wall middle portion 41, and a left side wall front portion 42.

  The left side wall rear portion 40 is formed in a substantially triangular shape in a side view (see FIG. 3). The left side wall rear portion 40 is formed in a substantially cylindrical protective portion 43 that protrudes outward (leftward), a through hole 44 surrounded by the protective portion 43, and a lower side of the through hole 44. Left rib 45 (see FIG. 7A). The left rib 45 is integrally provided with a first portion 45A that extends from the right side surface of the left side wall rear portion 40 to the right side and a second portion 45B that is bent forward from the right end portion of the first portion 45A.

  The left side wall middle portion 41 is formed in a substantially rectangular shape in side view with a smaller height than the left side wall rear portion 40, extends forward from the lower front end of the left side wall rear portion 40, bends outward in the middle of the front and rear direction, and further forward It bends and extends. The left side wall middle portion 41 has an opening 47 formed in a bent portion 46 bent outward in the middle thereof, and a frame U in which a portion rearward of the bent portion 46 from the opening 47 is cut out in a substantially U shape in a side view. It has a letter-shaped notch 48 and a long hole 49 formed in front of the opening 47.

  The inner surface of the frame U-shaped cutout portion 48 includes an upper surface portion 48A, a lower surface portion 48B, a curved portion 48C, a stepped portion 48D, and an inclined portion 48E as a first guide portion. The upper surface portion 48 </ b> A is located on the upper surface of the inner surface of the frame U-shaped cutout portion 48. The lower surface portion 48 </ b> B is located below the inner surface of the frame U-shaped cutout portion 48. The curved portion 48C is a curved surface that connects the upper surface portion 48A and the lower surface portion 48B. The step portion 48D extends upward from the front end of the lower surface portion 48B. The inclined portion 48E extends in the front upward direction from the upper end of the stepped portion 48D and is connected to the long hole 49.

  The long hole 49 is formed in a portion in front of the bent portion 46 so that the diameter in the front-rear direction is slightly longer than the diameter in the vertical direction.

The left side wall front portion 42 is formed to extend obliquely upward from the front end edge of the left side wall middle portion 41 toward the front.

  The right drum side wall 36 includes a right side wall rear portion 50, a right side wall middle portion 51, and a right side wall front portion 52.

  The right side wall rear portion 50 is formed in a substantially triangular shape in a side view. The right side wall rear portion 50 has a through hole 53 into which the drum right bearing 32 is fitted. The right side wall rear portion 50 faces the left side wall rear portion 40 in the left-right direction.

  The right side wall middle portion 51 is formed in a substantially rectangular shape in a side view smaller in height than the right side wall rear portion 50, extends forward from the lower front end of the right side wall rear portion 50, bends outward in the middle of the front-rear direction, and further forward It bends and extends. The right side wall middle portion 51 has an opening 55 formed in a bent portion 54 bent outward in the middle thereof, and a frame U in which a portion on the rear side of the bent portion 54 from the opening 55 is cut out in a substantially U shape in a side view. And a character-shaped notch 56.

  The inner surface of the frame U-shaped notch portion 56 includes an upper surface portion 56A, a lower surface portion 56B, a curved portion 56C, a step portion 56D, and an inclined portion 56E as a first guide portion. The upper surface part 56 </ b> A is located at the upper part of the inner surface of the frame U-shaped cutout part 56. The lower surface portion 56 </ b> B is located below the inner surface of the frame U-shaped cutout portion 56. The curved portion 56C is a curved surface that connects the upper surface portion 56A and the lower surface portion 56B. The step portion 56D extends upward from the front end of the lower surface portion 56B. The inclined portion 56E extends in the front upper direction from the upper end of the step portion 56D (see FIG. 9A).

The right wall front portion 52 is formed to extend obliquely upward from the front edge of the right wall middle portion 51 toward the front.

The drum rear wall 37 is provided between the rear end portion of the drum side wall 35 and the rear end portion of the drum side wall 36.

The drum upper wall 38 is provided between the upper end portion of the left side wall rear portion 40 of the drum side wall 35 and the upper end portion of the right side wall rear portion 50 of the drum side wall 36.

The drum front wall 39 is constructed between the lower end portion of the left side wall front portion 42 of the drum side wall 35 and the lower end portion of the right side wall front portion 52 of the drum side wall 36 and is formed so as to be inclined obliquely upward as it goes forward. Has been. On the drum front wall 39, pressing members 34 for pressing the developing cartridge 9 toward the photosensitive drum 5 are provided at two positions across the center in the left-right direction.

  The left side wall middle part 41 and the left side wall front part 42 of the drum side wall 35 and the right side wall middle part 51 and the right side wall front part 52 of the drum side wall 36 form the developing cartridge housing part 16.

  The photosensitive drum 5 is held by the left side wall rear portion 40 of the drum side wall 35 and the right side wall rear portion 50 of the drum side wall 36. The photosensitive drum 5 includes a cylindrical drum main body 57 and a drum shaft 58 extending along the central axis of the drum main body 57.

  The flange member 30 is fixed to both ends of the drum main body 57 as shown in FIGS. Each flange member 30 is rotatable relative to the drum shaft 58.

  As shown in FIG. 7A, the drum left bearing 31 holds the flange member 30 fixed to the left end portion of the drum body 57 so as to be relatively rotatable, and is fitted in the through hole 44 of the drum frame 29.

  As shown in FIG. 2, the drum right bearing 32 holds the flange member 30 fixed to the right end portion of the drum main body 57 so as to be relatively rotatable, and projects rightward from the through hole 53 of the drum frame 29. The right end portion of the drum shaft 58 is inserted into the drum right bearing 32 so as not to rotate relative to the drum shaft 58, and protrudes rightward from the drum right bearing 32. Accordingly, the drum body 57 of the photosensitive drum 5 is provided between the left side wall rear portion 40 and the right side wall rear portion 50 so as to be rotatable around the drum shaft 58.

As shown in FIG. 3, the connecting member 33 is attached to the end face of the left flange member 30 exposed at a portion surrounded by the protection portion 43.
3. Drum Bearing A detailed configuration of the drum bearing will be described. FIG. 6 is a perspective view (a) and a side view (b) of the drum left bearing 31. FIGS. 7A and 7B are views for explaining the mounting of the drum left bearing 31 to the drum frame 29. FIG. In FIG. 7A, the drum cartridge other than the drum left bearing 31 is omitted. FIG. 8 is a perspective view (a) and a side view (b) of the drum right bearing 32. FIGS. 9A and 9B are views for explaining the mounting of the drum right bearing 32 to the drum frame 29. FIG.

(1) Drum Left Bearing The drum left bearing 31 is made of POM (polyacetal), which is a material having higher slidability than the drum frame 29. As shown in FIG. 6A, the drum left bearing 31 includes a cylindrical portion 59 formed in a cylindrical shape, an annular plate-shaped annular portion 60 that spreads outward from the right peripheral edge of the cylindrical portion 59, and And a support portion 61 protruding forward from the outer peripheral edge of the annular portion 60.

  The cylindrical portion 59 has an outer diameter slightly smaller than the inner peripheral surface of the through hole 44 in a portion surrounded by the protective portion 43 formed in the left side wall rear portion 40 and is fitted into the through hole 44.

  The annular portion 60 includes an annular plate-shaped base portion 60A, a first convex portion 60B, a second convex portion 60C, and a third convex portion 60D. The first convex portion 60B has a slightly thick plate shape in the left-right direction, and protrudes radially outward from the outer peripheral edge of the base portion 60A. The second convex portion 60C protrudes leftward from the outer peripheral edge of the base portion 60A, and bends radially outward in the middle. The third convex portion 60D has a thin plate shape in the width direction, and protrudes radially outward from the outer peripheral edge of the base portion 60A.

  The support part 61 protrudes from the outer peripheral edge of the base part 60 </ b> A of the annular part 60. The support portion 61 includes an upper end edge 61A, a lower end edge 61B, an upper front end edge 61C, a lower front end edge 61D, and a second guide portion 61E. The upper edge 61A and the lower edge 61B extend in a straight line from the outer peripheral edge of the base portion 60A of the annular portion 60 to the front so as to be substantially parallel to each other. The upper front edge 61C extends linearly from the front edge of the upper edge 61A diagonally forward and downward, extends downward in the middle, and extends linearly in the rear downward direction. The lower front edge 61D extends linearly upward from the front edge of the lower edge 61B.

  The second guide portion 61E includes an upper guide surface 62 extending rearward from the rear lower end of the upper front end edge 61C, a lower guide surface 63 extending rearward from the upper end of the lower front end edge 61D, and the upper guide surface 62 and the lower guide. A curved surface 64 that connects the surface 63 is provided. The upper guide surface 62 and the lower guide surface 63 are in contact with the outer peripheral surface of the color member 26 of the developing roller 8 when the developing cartridge 9 is mounted on the drum cartridge 7.

  Next, a method for attaching the drum left bearing 31 to the drum frame 29 will be described. First, the cylindrical portion 59 of the drum left bearing 31 is fitted into the through hole 44. At this time, the portion of the drum left bearing 31 on the right side of the cylindrical portion 59 does not contact the left rib 45, the third convex portion 60D is obliquely forward and upward with respect to the left rib 45, and the first convex portion 60B is upward. Position it so that it faces you. Then, the first convex portion 60B is pushed, and the drum left bearing 31 is rotated counterclockwise in the direction in which the third convex portion 60D approaches the left rib 45 (see the thick arrow in the drawing). Thereafter, when the third convex portion 60D comes into contact with the first portion 45A of the left rib 45, the third convex portion 60D engages with the drum side wall 35 on the left side of the drum frame 29 in the left rib 45, and the drum left bearing 31 The rotation stops. Thereby, the installation of the drum left bearing 31 is completed.

  As shown in FIG. 7A, the lower guide surface 63 of the drum left bearing 31 and the inclined portion 48E of the left side wall middle portion 41 are provided with a stepped portion 48D of the left side wall middle portion 41 and a lower front end edge 61D of the support portion 61. Since the vertical lengths are equal, they are on the same plane. The linear distance A between the upper guide surface 62 and the lower guide surface 63 in the drum left bearing 31 is shorter than the linear distance B between the upper surface portion 48A and the lower surface portion 48B of the frame U-shaped notch 48 in the left drum side wall 35. . Specifically, the linear distance A between the upper guide surface 62 and the lower guide surface 63 of the drum left bearing 31 is substantially equal to the diameter of the cylindrical portion of the collar member 26. Therefore, the collar member 26 contacts the upper guide surface 62 and the lower guide surface 63, but does not contact the upper surface portion 48A and the lower surface portion 48B of the frame U-shaped cutout portion 48 of the left drum side wall 35.

(2) Drum right bearing The drum right bearing 32 is made of POM (polyacetal), which is a material having higher slidability than the drum frame 29. As shown in FIG. 8A, the drum right bearing 32 includes a left cylindrical portion 65 formed in a cylindrical shape, a right cylindrical portion 66 formed in a cylindrical shape, and a peripheral edge on the right side of the left cylindrical portion 65. An annular plate-shaped annular part 67 that spreads outward and a support part 68 that protrudes forward from the outer peripheral edge of the annular part 67 are provided.

  The left cylindrical portion 65 includes a first cylindrical portion 65A that protrudes in a cylindrical shape from the left end of the annular portion 67 to the left side, and a second cylindrical portion 65B that protrudes from the first cylindrical portion 65A and has a smaller outer diameter than the first cylindrical portion 65A. And a third cylindrical portion 65C that protrudes from the second cylindrical portion 65B and has an outer diameter smaller than that of the second cylindrical portion 65B and is fitted to the photosensitive drum 5.

  The right cylindrical portion 66 has an outer diameter slightly smaller than the inner peripheral surface of the through hole 53 and is fitted into the through hole 53.

  The support portion 68 protrudes from the outer peripheral edge of the annular portion 67. The support portion 68 includes an upper end edge 68A, a lower end edge 68B, an upper front end edge 68C, a lower front end edge 68D, and a second guide portion 68E. The upper end edge 68A and the lower end edge 68B extend linearly from the outer peripheral edge of the annular portion 67 to the front so as to be substantially parallel to each other. The upper front edge 68C extends in a curved shape from the front end of the upper edge 68A in the rear lower direction.

  The second guide portion 68E includes an upper guide surface 69 extending rearward from the rear lower end of the upper front end edge 68C, a lower guide surface 70 extending rearward from the upper end of the lower front end edge 68D, and the upper guide surface 69 and the lower guide. A curved surface 71 that connects the surface 70 is provided. The upper guide surface 69 and the lower guide surface 70 are in contact with the outer peripheral surface of the color member 27 of the developing roller 8 when the developing cartridge 9 is mounted on the drum cartridge 7.

As shown in FIG. 9B, the lower guide surface 70 of the drum right bearing 32 and the inclined portion 56E of the right side wall middle portion 51 include a step portion 56D of the right side wall middle portion 51 and a lower front end edge 68D of the support portion 68. Since the vertical lengths are equal, they are on the same plane. The linear distance C between the upper guide surface 69 and the lower guide surface 70 in the drum right bearing 32 is shorter than the linear distance D between the upper surface portion 56A and the lower surface portion 56B of the frame U-shaped notch 56 in the right drum side wall 36. . Specifically, the linear distance C between the upper guide surface 69 and the lower guide surface 70 of the drum right bearing 32 is substantially equal to the diameter of the cylindrical portion of the collar member 27. Therefore, the collar member 27 contacts the upper guide surface 69 and the lower guide surface 70, but does not contact the upper surface portion 56A and the lower surface portion 56B of the frame U-shaped cutout portion 56 of the right drum side wall 36.
4). Pressing / separating operation of the developing roller The pressing / separating operation of the developing roller 8 will be described with reference to FIG. FIG. 10A is a diagram illustrating a state in which the developing roller 8 is pressed against the photosensitive drum 5. FIG. 10B is a diagram illustrating a state in which the developing roller 8 is separated from the photosensitive drum 5. 10A and 10B show the right side surface of the process cartridge 3.

  The printer 1 includes a pair of linear cam members 72 provided on the side wall of the main body casing 2. The linear cam member 72 has a thin plate shape extending in the front-rear direction along the inner surface of the main casing 2. The linear cam member 72 includes four cutouts 73 formed in a substantially rectangular shape that is long in the front-rear direction at equal intervals in the front-rear direction, and a connecting part 74 that connects the cutouts 73 linearly.

  The notch 73 includes a front surface portion 73A that linearly extends downward from the rear end of the connecting portion 74, a bottom surface portion 73B that linearly extends rearward from the lower end of the front surface portion 73A, and a diagonally upward direction from the rear end of the bottom surface portion 73B. And an inclined portion 73C extending linearly.

  The housing 17 of the developing cartridge 9 contacts the pressing member 34 when the developing cartridge 9 is mounted on the drum cartridge 7 (see FIG. 2). The developing roller 8 is pressed against the photosensitive drum 5 by the pressing force (biasing force) of the pressing member 34. That is, the developing roller 8 is located at a contact position where it contacts the photosensitive drum 5. As shown in FIG. 10A, the separating portion 21 of the developing cartridge 9 is located at a distance from the bottom surface portion 73 </ b> B of the linear motion cam member 72 when the developing roller 8 is located at the contact position. The color member 27 of the developing roller shaft 24 is located at the second guide portion 68E, and the outer peripheral surface of the color member 27 is in contact with the upper guide surface 69 and the lower guide surface 70 of the second guide portion 68E. From this state, when a driving force of a motor (not shown) is input to the linear cam member 72 and the linear cam member 72 is moved forward, the separating portion 21 is inclined as shown in FIG. It moves to the position of the connection part 74 of the linear cam member 72 through 73C. Thereby, the developing roller 8 and the photosensitive drum 5 are separated. That is, the developing roller 8 is located at a separated position away from the photosensitive drum 5. When the developing roller 8 is located at the separated position, the outer peripheral surface of the color member 27 has the right end of the outer periphery of the color member 27 of the developing roller shaft 24 protruding from the second guide portion 68E to the right side. It does not contact the middle wall portion 51 but contacts the upper guide surface 69 and the lower guide surface 70 of the second guide portion 68E.

  As described above, the drum bearings 31 and 32 support the color members 26 and 27 that cover the end portions of the developing roller shaft 24 that moves between the contact position and the separation position. Compared with the case of supporting the frame 29, the frictional resistance of the collar members 26 and 27 is reduced. Therefore, the contact state between the photosensitive drum 5 and the developing roller 8 is stable, and good image formation is possible.

Further, even when the developing roller 8 is located at the separated position, the collar members 26 and 27 are in contact with the upper guide surfaces 62 and 69 and the lower guide surfaces 63 and 70, so that the movement from the separated state to the contact state is achieved. Smooth.
5. Mounting of Developing Cartridge on Drum Cartridge Mounting of developing cartridge 9 on drum cartridge 7 will be described with reference to FIG.
A dotted line in FIG. 10A represents a state in which the collar member 27 is being attached to the drum cartridge 7.

The developing cartridge 9 is attached to the drum cartridge 7 from the front of the photosensitive drum 5. In this mounting, first, the collar member 27 protruding from the housing 17 of the developing cartridge 9 to the left and right sides is fitted into the inclined portion 56E (see FIG. 9A), and the outer peripheral surface of the color member 27 is inclined to the inclined portion 56E. To touch. When the developing cartridge 9 is pushed rearward, the developing cartridge 9 moves rearward while being guided by the collar member 27 contacting the upper guide surface 69 of the drum bearing and the lower guide surface 70 of the drum bearing.

  As described above, since the inclined portion 56E and the lower guide surface 70 are coplanar, the color member 27 is guided when the developing cartridge 9 is mounted on the drum cartridge 7, so that the developing cartridge 9 can be easily removed. It can be attached to the drum cartridge 7.

  During this movement, the housing 17 of the developing cartridge 9 abuts against the pressing member 34, and the housing 17 is pushed downward against the pressing force of the pressing member 34. Installation is complete. In this state, in the developing cartridge 9, the developing roller 8 is pressed against the photosensitive drum 5 by the pressing force (biasing force) of the pressing member 34. Although the right side wall 35 has been described, the same applies to the left side wall 36.

  In this embodiment, the end portion of the developing roller shaft 24 is covered with the color members 26 and 27, but it is not necessary to cover it.

DESCRIPTION OF SYMBOLS 1 Printer 3 Process cartridge 5 Photosensitive drum 7 Drum cartridge 8 Developing roller 9 Developing cartridge 16 Developing cartridge accommodating part 24 Developing roller shaft 26 Color member 27 Color member 29 Drum frame 31 Drum left bearing 32 Drum right bearing 48E Inclining part 56E Inclining part 61 Support part 61E Second guide part 68 Support part 68E Second guide part

Claims (5)

A photosensitive drum on which an electrostatic latent image is formed; a frame in which the photosensitive drum is accommodated and having a developing cartridge accommodating portion; and a drum that rotatably supports an axial end portion of the photosensitive drum with respect to the frame. A drum cartridge having a bearing;
A developing cartridge having a developing roller and detachably mounted in the developing cartridge housing portion,
The developing roller is movable between a contact position in contact with the photosensitive drum and a separated position separated from the photosensitive drum in a state where the developing cartridge is mounted on the drum cartridge.
The process cartridge according to claim 1, wherein the drum bearing has a support portion that supports an end portion in the axial direction of the developing roller that moves between the contact position and the separation position. The frame has a first guide portion that guides the developing roller when the developing cartridge is mounted on the drum cartridge;
The support portion is disposed downstream of the first guide portion in the mounting direction of the developing cartridge, and has a second guide portion that guides the developing roller continuously with the first guide portion. The process cartridge according to claim 1.   The process cartridge according to claim 2, wherein the end portion of the developing roller is in contact with the second guide portion at the separation position. The developing roller has a rotation shaft,
4. The process cartridge according to claim 1, wherein the support portion supports a collar member that covers an end portion of the rotating shaft in the axial direction. 5.   5. The process cartridge according to claim 1, wherein the drum bearing is made of a material having a higher slidability than a material of the frame.