JP5062233B2 - Process cartridge - Google Patents

Description

  The present invention relates to a process cartridge provided in an image forming apparatus such as a laser printer.

As a process cartridge provided in an electrophotographic printer, a photosensitive member carrying an electrostatic latent image on the surface and a developing roller carrying a developer on the surface and supplying the developer to the photosensitive member are rotatably supported. Process cartridges are known.
For example, a process cartridge that supports a developing roller and a photosensitive member so as to be in pressure contact with each other has been proposed (see, for example, Patent Document 1).

An image carrier cover is attached to the process cartridge so as to cover the photosensitive member when it is not attached to the image forming apparatus. The image carrier cover is integrally provided with a separation member that separates the developing roller and the photosensitive member.
In this process cartridge, when the image carrier cover is mounted so as to cover the photosensitive member, the developing roller and the photosensitive member are separated by the separation member, and the developing roller and the photosensitive member are in contact with each other at the same portion for a long time. By continuing to do so, it is possible to prevent the occurrence of pressure marks and the like.

JP 2001-282079 A

  However, in the process cartridge described in Patent Document 1 described above, when the image carrier cover is mounted, between the first housing block that supports the developing roller and the second housing block that supports the photosensitive member, The first housing block and the second housing block are pushed against the biasing force of the spring that biases the first housing block and the second housing block so that the developing roller and the photosensitive member are pressed against each other. A spacing member is inserted so as to spread.

Therefore, in order to mount the image carrier cover, a strong pressing force is required to spread the first housing block and the second housing block against the biasing force of the spring.
As a result, there is a problem that it is difficult to mount the image carrier cover. Also, there is a problem that the separation member is damaged by a strong pressing force acting on the separation member of the image carrier cover.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a process cartridge that can be easily and surely attached with a simple configuration and can reliably protect an image carrier.

In order to achieve the above object, the present invention is a process cartridge that is detachable from an image forming apparatus main body, and is configured to be able to carry an image carrier on which an electrostatic latent image is formed and a developer. And a developer carrier configured to be movable between a pressure contact position where the developer can be supplied to the image carrier by being in pressure contact with the image carrier, and a spaced position separated from the image carrier , A casing for detachably holding the image carrier and the developer carrier, and a casing mounted on the casing so as to cover the image carrier when the process cartridge is detached from the image forming apparatus main body. And an elastically deformable pressure contact force reducing member that is provided only at one end of the cover in the longitudinal direction of the image carrier and reduces the pressure contact force between the image carrier and the developer carrier. , When the cover is mounted on the casing, the pressure contact force reducing member overlaps with the one end portion in the longitudinal direction of the developer carrying member when projected in the longitudinal direction, and is directed to the other side in the longitudinal direction. It is characterized by having an urging force .

According to the present invention, the pressing force reducing member is provided only at one end of the cover that covers the image carrier in the longitudinal direction of the image carrier.
Therefore, after the cover is mounted, the pressure contact force reducing member can be applied to one end portion in the longitudinal direction of the image carrier and the developer carrier with the other end portion in the longitudinal direction as a fulcrum.
As a result, the pressure contact force between the image carrier and the developer carrier is reduced with a weak pressing force compared to the case where the pressure contact force between the image carrier and the developer carrier is reduced at both ends in the longitudinal direction of the image carrier. Can be made.

  As a result, the cover can be easily and reliably attached with a simple configuration, and the image carrier can be reliably protected.

1 is a side sectional view showing a printer of the present invention. FIG. 2 is a perspective view of the process cartridge shown in FIG. 1 as viewed from the lower left in a state where the process cartridge is detached from a main body casing and a cover is attached. It is the perspective view seen from the upper left of the cover shown in FIG. It is a rear view of the cover shown in FIG. It is explanatory drawing for demonstrating mounting | wearing of the cover to a process cartridge, Comprising: The state which made the coupling engaging part engage with the coupling cover of a process cartridge is shown. It is explanatory drawing for demonstrating mounting | wearing of the cover to a process cartridge, Comprising: The cover is mounted | worn to a process cartridge and the drum shaft engaging part is shown in the state elastically deformed. FIG. 7 is a right side view of the process cartridge and the cover shown in FIG. 6. FIG. 6 is an explanatory diagram for explaining attachment of a cover to a process cartridge, in which a right end portion of a developing roller is moved upward so as to be separated from a photosensitive drum, and a contact portion of a drum shaft engaging portion is developed from below. The state which is contact | abutted to the roller shaft is shown. It is explanatory drawing for demonstrating reduction of the press-contact force of a developing roller and a photosensitive drum. FIG. 9 is a perspective view of the process cartridge according to the second embodiment, as viewed from the lower left in a state where the process cartridge is detached from the main body casing and a cover is attached. It is the perspective view seen from the upper right of the cover shown in FIG. It is a rear view of the cover shown in FIG. In the process cartridge of 2nd Embodiment, it is explanatory drawing for demonstrating reduction of the press contact force of a developing roller and a photosensitive drum.

1. Overall Configuration of Printer As shown in FIG. 1, the printer 1 is a direct tandem type color printer. The printer 1 includes a main body casing 2 as an example of an image forming apparatus main body. In the main body casing 2, four process cartridges 3 (3K, 3Y, 3M, 3C) are provided corresponding to the respective colors of black, yellow, magenta, and cyan. The process cartridges 3 are arranged in parallel at equal intervals in the order of black, yellow, magenta, and cyan from the upstream side in the conveyance direction of the paper P by the conveyance belt 11 described later.

In the following description, the upstream side in the conveyance direction of the paper P by the conveyance belt 11 (described later) (the left side in FIG. 1) is the front side, and the opposite side (the right side in FIG. 1) is the rear side. In addition, when the printer 1 is viewed from the front side, the left and right reference is used. That is, the front side in FIG. 1 is the right side and the back side is the left side.
Each process cartridge 3 can be attached to and detached from the inside of the main body casing 2 with the top cover 4 provided on the upper surface of the main body casing 2 being opened.

As will be described later, each process cartridge 3 includes a photosensitive drum 5 as an example of an image carrier, a scorotron charger 6, a developing roller 7 as an example of a developer carrier, and a cleaning roller 8.
The scorotron charger 6, the developing roller 7 and the cleaning roller 8 are arranged around the photosensitive drum 5. The scorotron charger 6 is opposed to the surface of the photosensitive drum 5 with a gap. The developing roller 7 and the cleaning roller 8 are provided with their peripheral surfaces in contact with the surface of the photosensitive drum 5.

In the main casing 2, four LED units 9 corresponding to the process cartridge 3 are provided. The tip of each LED unit 9 faces the peripheral surface of the photosensitive drum 5.
During the image forming operation, the photosensitive drum 5 is rotated at a constant speed counterclockwise in FIG. Further, electric charges are emitted from the scorotron charger 6 to the surface of the photosensitive drum 5. As a result, the surface of the photosensitive drum 5 is charged positively from the portion facing the scorotron charger 6.

  When the charged portion of the surface of the photosensitive drum 5 faces the LED unit 9 as the photosensitive drum 5 rotates, the charged portion is selected by an LED (not shown) provided at the tip of the LED unit 9. Exposed to light. The charge is removed from the exposed portion of the surface of the photosensitive drum 5, and an electrostatic latent image is formed on the surface of the photosensitive drum 5 due to a potential difference (presence / absence of charge).

  Further, a positive developing bias is applied to the developing roller 7 to carry toner as an example of a developer. When the electrostatic latent image faces the developing roller 7 as the photosensitive drum 5 rotates, the electrostatic latent image is positively charged from the developing roller 7 to the electrostatic latent image by the potential difference between the developing roller 7 and the surface of the photosensitive drum 5. Toner is supplied. As a result, the electrostatic latent image is developed into a toner image, and the toner image is carried on the surface of the photosensitive drum 5.

A paper feed cassette 10 that accommodates the paper P is disposed at the bottom of the main casing 2. The paper P stored in the paper feed cassette 10 is transported onto the transport belt 11 by various rollers.
The conveyor belt 11 is disposed facing the four photosensitive drums 5 from below. A transfer roller 12 is disposed at each position facing each photosensitive drum 5 across the upper portion of the transport belt 11. The paper P transported on the transport belt 11 sequentially passes between each photosensitive drum 5 and the transport belt 11 as the transport belt 11 travels. The toner image on the surface of the photosensitive drum 5 is transferred to the paper P passing between the photosensitive drum 5 and the transport belt 11 by the transfer bias of the transfer roller 12.

A fixing device 13 is provided on the downstream side in the conveyance direction of the paper P with respect to the conveyance belt 11. The sheet P on which the toner image is transferred is conveyed to the fixing device 13. In the fixing device 13, the toner image is fixed on the paper P by heating and pressing. The paper P on which the toner image is fixed is discharged to a paper discharge tray 14 on the upper surface of the main body casing 2 by various rollers.
During the image forming operation, a negative recovery bias is applied to the cleaning roller 8. After the transfer of the toner image from the photosensitive drum 5 to the paper P, deposits such as toner remaining on the surface of the photosensitive drum 5 and paper dust of the paper P face the cleaning roller 8 as the photosensitive drum 5 rotates. Is collected by the cleaning roller 8.
2. Details of Process Cartridge As shown in FIGS. 1 and 2, the process cartridge 3 includes a casing 21 and a developing cartridge 22.

The casing 21 extends in the left-right direction and is formed in a substantially rectangular bottomed frame shape. The casing 21 includes a drum holding part 23 and a cartridge mounting part 24.
The drum holding portion 23 is provided on the lower side portion of the casing 21. The drum holding unit 23 includes a coupling cover 25 and supports the photosensitive drum 5.
The coupling cover 25 is formed in a substantially cylindrical shape protruding leftward at the left end portion of the drum holding portion 23.

  The photosensitive drum 5 includes a drum shaft 15 provided along the left-right direction, and a drum coupling female member 30 provided at the left end portion of the drum shaft 15 so as not to be relatively rotatable. A drum coupling male member (not shown) provided in the main body casing 2 is fitted to the drum coupling female member 30 from the left side, and a driving force from a driving source (not shown) of the main body casing 2 is input. Is done.

  The drum coupling female member 30 is rotatably supported in the coupling cover 25, and the right end portion of the drum shaft 15 penetrates the right wall of the drum holding portion 23 and protrudes to the right. It is supported rotatably. As a result, the photosensitive drum 5 is rotatably supported by the drum holding unit 23. The coupling cover 25 and the drum coupling female member 30 constitute a drive receiving portion.

  The cartridge mounting unit 24 is provided above the drum holding unit 23 in succession to the drum holding unit 23 and accommodates the developing cartridge 22 in a detachable manner. A pressing member 26 is provided at the upper end of the cartridge mounting portion 24 (see FIG. 5). Further, developing roller shaft fitting holes 27 are formed at both left and right ends of the cartridge mounting portion 24 (see FIG. 7).

The pressing member 26 presses the upper end portion of the developing cartridge 22 downward when the developing cartridge 22 is mounted (see FIG. 5).
The developing roller shaft fitting hole 27 is formed in a substantially rectangular shape in side view extending in the vertical direction (see FIG. 7). The developing roller shaft fitting hole 27 is formed to receive a developing roller shaft 28 (described later).

The developing cartridge 22 is formed in a substantially box shape extending in the left-right direction. The developing cartridge 22 includes a developing roller 7.
The developing roller 7 is rotatably supported by the lower end portion of the developing cartridge 22 so as to be exposed rearward from the rear lower end portion of the developing cartridge 22. The developing roller 7 includes a developing roller shaft 28 and a coating layer 29.

The developing roller shaft 28 is a rotating shaft of the developing roller 7 and is formed in a bar shape extending in the left-right direction from a conductive material such as metal.
The covering layer 29 is a rubber roller made of an elastic material such as semiconductive rubber and covers the central portion in the left-right direction of the developing roller shaft 28 (see FIG. 9).
The developing cartridge 22 is mounted on the cartridge mounting portion 24 so that the upper end of the developing cartridge 22 comes into contact with the pressing member 26 of the cartridge mounting portion 24 from below. Further, both left and right end portions of the developing roller shaft 28 are loosely fitted in the developing roller shaft fitting holes 27 of the cartridge mounting portion 24 from the inner side in the left and right direction.

The developing cartridge 22 is pressed toward the photosensitive drum 5 by being pressed downward by the pressing member 26. At the same time, the developing roller 7 is also pressed against the photosensitive drum 5 (pressing position) .
The developing cartridge 22 is provided so as to be lifted upward and separated from the photosensitive drum 5 by a contact / separation mechanism (not shown) of the main casing 2 against the urging force of the pressing member 26. . That is, the casing 21 accommodates the photosensitive drum 5 and the developing roller 7 so as to be able to contact and separate.

As shown in FIGS. 3 and 4, the cover 31 extends in the left-right direction and is formed in a partial cylindrical shape having a substantially fan shape in side view. The cover 31 is formed so as to cover the drum holding portion 23 almost completely from the lower rear when mounted on the process cartridge 3.
The cover 31 includes a covering portion 32 extending in the left-right direction, a coupling engaging portion 33 provided at the left end portion of the covering portion 32, and a drum as an example of a pressure contact force reducing member provided at the right end portion of the covering portion 32. A shaft engaging portion 34 is provided.

The covering portion 32 is formed in a substantially L shape in a side sectional view extending in the left-right direction, and constitutes a front end portion and a lower end portion of the cover 31. The covering portion 32 includes a drum protection portion 35 and a tip protection portion 36.
The drum protection part 35 is provided in the front end part of the coating | coated part 32, and is formed in the cross-sectional view substantially L shape extended in the left-right direction. Specifically, the drum protection portion 35 extends downward from the upper end portion of the covering portion 32, and is then curved rearward along the outer peripheral surface of the photosensitive drum 5.

  The tip protection part 36 is provided continuously behind the drum protection part 35. Further, the front end protection part 36 is formed in a groove shape having a substantially U-shape in a side sectional view that extends in the left-right direction and protrudes upward from the rear end edge of the drum protection part 35 so as to protrude downward. . Further, the groove width (length in the front-rear direction) of the front end protection portion 36 is formed to a length that can receive the lower rear end portion of the process cartridge 3.

The coupling engaging portion 33 extends from the left end edge of the covering portion 32 in the up / down and front / rear directions, and includes a coupling fitting hole 37 and a coupling covering portion 38 as an example of the covering portion.
The coupling fitting hole 37 is provided so as to penetrate the coupling engaging portion 33 in the left-right direction. The coupling fitting hole 37 is a long hole extending in the vertical direction, and is formed in a size that can receive the coupling cover 25 of the process cartridge 3.

The coupling covering portion 38 protrudes rightward from the upper peripheral edge of the coupling fitting hole 37 and is formed in a partially cylindrical shape having a substantially U shape in side view and opened downward. A flange 39 is formed at the left end of the coupling covering portion 38 so as to protrude radially inward of the coupling covering portion 38.
The drum shaft engaging portion 34 is formed in a plate shape that is elastically deformable and extends in the up-down and front-rear directions continuously from the right edge of the covering portion 32. That is, the drum shaft engaging portion 34 is provided integrally with the cover 31. The drum shaft engaging portion 34 includes a drum shaft fitting hole 40 as an example of a housing portion, a contact portion 41 as an example of a holding portion, and an operation portion 42.

The drum shaft fitting hole 40 is provided so as to penetrate the drum shaft engaging portion 34 in the left-right direction. The drum shaft fitting hole 40 is formed in a substantially rectangular shape in side view extending in the vertical direction, and the longitudinal length of the upper end portion thereof is longer than the radial length of the drum shaft 15 of the photosensitive drum 5 (see FIG. 7). .
The contact portion 41 is formed in a bent flat plate shape and is provided above the drum shaft fitting hole 40. Specifically, the abutting portion 41 continuously protrudes from the upper end edge of the drum shaft engaging portion 34 toward the right, and then is bent upward and extends upward.

The operation portion 42 is formed in a flat plate shape extending from the upper end edge of the drum shaft engaging portion 34 to the upper left side behind the contact portion 41.
(2) Mounting of Cover Next, with reference to FIGS. 5 to 8, mounting of the cover 31 to the process cartridge 3 will be described.

In order to attach the cover 31 to the process cartridge 3, as shown in FIG. 5, first, the coupling engaging portion 33 of the cover 31 is engaged with the coupling cover 25 of the process cartridge 3.
In order to engage the coupling engaging portion 33 with the coupling cover 25, the cover 31 is brought close to the process cartridge 3 from below. At this time, the process cartridge 3 is made to approach obliquely from the left end portion of the cover 31.

Then, the coupling cover 25 is inserted into the coupling fitting hole 37 and the coupling covering portion 38 is put on the coupling cover 25 from below.
As a result, the coupling cover 25 and the drum coupling female member 30 (drive receiving portion) are covered by the coupling covering portion 38 from below and from the left. Further, the position of the coupling engaging portion 33 of the cover 31 is fixed with respect to the coupling cover 25 of the process cartridge 3.

Next, the cover 31 is swung with the developing roller shaft 28 as a fulcrum, and the left end portion of the cover 31 is brought close to the process cartridge 3 from below.
Since the drum shaft engaging portion 34 is provided so as to overlap the right end portion of the drum shaft 15 in the vertical direction, the drum shaft engagement portion 34 can be obtained simply by bringing the right end portion of the cover 31 close to the process cartridge 3 as it is. The joining portion 34 interferes with the drum shaft 15 from below, and further swinging of the cover 31 is restricted.

Therefore, the operating portion 42 is pulled rightward and the drum shaft engaging portion 34 is bent to the right so as not to interfere with the drum shaft 15, and the right end portion of the cover 31 is moved downward with respect to the process cartridge 3. From close.
Then, the cover 31 is placed on the process cartridge 3 so that the drum shaft 15 is inserted into the upper end portion of the drum shaft fitting hole 40 from the left, and then the pulling of the operation unit 42 is released.

Then, as shown in FIG. 6, the drum shaft engaging portion 34 moves to the left due to its elasticity, and the drum shaft 15 is inserted into the upper end portion of the drum shaft fitting hole 40 from the left.
Thus, the right end portion of the drum shaft 15 is accommodated in the drum shaft fitting hole 40, and the mounting of the cover 31 to the process cartridge 3 is completed.
At this time, the contact portion 41 of the drum shaft engaging portion 34 is in contact with the right end portion of the developing roller shaft 28 from the right as shown in FIG. That is, the drum shaft engaging portion 34 overlaps the right end portion of the developing roller shaft 28 when projected in the left-right direction. The drum shaft engaging portion 34 is exposed to the outside of the casing 21 on the right side of the drum holding portion 23.

As a result, the drum shaft engaging portion 34 is pressed rightward by the right end portion of the developing roller shaft 28. That is, the drum shaft engaging portion 34 is continuously elastically deformed to the right and has a biasing force to the left.
Next, the right end portion of the developing roller shaft 28 is moved upward to reduce the pressure contact force between the developing roller 7 and the photosensitive drum 5.

In order to move the right end portion of the developing roller shaft 28 upward, the right end portion of the developing roller shaft 28 is pulled upward.
Then, as shown in FIG. 9, the developing roller 7 is pressed against the photosensitive drum 5 at the left end, and is separated from the photosensitive drum 5 at the right end against the pressing force against the photosensitive drum 5 ( Separation position) . That is, the pressure contact force between the developing roller 7 and the photosensitive drum 5 is reduced in the longitudinal direction. At this time, the left end of the photosensitive drum 5 and the left end of the developing roller 7 are in contact outside the image forming area.

Further, when the right end portion of the developing roller shaft 28 moves upward, the contact portion 41 of the drum shaft engaging portion 34 is disengaged from the right end portion of the developing roller shaft 28 and is moved to the left by the biasing force. The
When the lifting of the developing roller shaft 28 to the right end is released, the right end portion of the developing roller shaft 28 is brought into contact with the contact portion 41 of the drum shaft engaging portion 34 from above as shown in FIG. The upward movement of the developing roller shaft 28 is maintained as it is.

As a result, the contact force 41 between the photosensitive drum 5 and the developing roller 7 is reduced by the contact portion 41 of the drum shaft engaging portion 34, and the reduction in the pressure contact force between the photosensitive drum 5 and the developing roller 7 is maintained. The
In this way, the pressure contact force between the developing roller 7 and the photosensitive drum 5 can be reduced.
4). Effect (1) According to the process cartridge 3, the contact portion 41 of the drum shaft engaging portion 34 is provided only at the right end portion of the cover 31 covering the photosensitive drum 5, as shown in FIG. .

Therefore, as shown in FIG. 9, after the cover 31 is mounted, the drum shaft engaging portion 34 is brought into contact with the right end portion of the developing roller 7 with the left end portion of the developing roller 7 as a fulcrum, and the right end of the developing roller 7 Only the portion can be separated from the photosensitive drum 5.
As a result, the developing roller 7 is separated from the photosensitive drum 5 at both ends in the left-right direction, and compared with the case where the pressure contact force between the photosensitive drum 5 and the developing roller 7 is reduced, the photosensitive drum 5 and the developing roller 7 are weakened. Pressure contact force can be reduced.

As a result, the cover 31 can be easily and reliably attached with a simple configuration, and the photosensitive drum 5 can be reliably protected.
(2) Further, according to this process cartridge 3, as shown in FIGS. 6 and 7, when the cover 31 is mounted on the casing 21, the contact portion 41 of the drum shaft engaging portion 34 is moved in the left-right direction. When projected, it overlaps the right end of the developing roller shaft 28 and has a biasing force to the left.

  Therefore, when the cover 31 is mounted on the casing 21 and then projected in the left-right direction, the developing roller shaft 28 prevents the contact portion 41 of the drum shaft engaging portion 34 from overlapping the right end portion of the developing roller shaft 28. Is once moved upward (in a direction away from the photosensitive drum 5), the contact portion 41 of the drum shaft engaging portion 34 is disengaged from the right end portion of the developing roller shaft 28 and left by the biasing force. To the right end of the developing roller shaft 28 from below.

Then, the right end portion of the developing roller shaft 28 is held in a state of being moved upward (in a direction away from the photosensitive drum 5) by contact with the contact portion 41 of the drum shaft engaging portion 34.
As a result, it is possible to maintain a state where the pressure contact force between the photosensitive drum 5 and the developing roller 7 is reduced.
As a result, with a simple configuration, the pressure contact force between the developing roller 7 and the photosensitive drum 5 can be reliably reduced, and the photosensitive drum 5 can be reliably protected.
(3) Also, according to this process cartridge 3, as shown in FIGS. 6 and 7, when the cover 31 is attached to the casing 21, the drum shaft engaging portion 34 is formed by the right end portion of the developing roller shaft 28. By being pressed rightward, it is elastically deformed.

Therefore, when the cover 31 is attached to the casing 21, if the drum shaft engaging portion 34 is elastically deformed by interfering with the right end portion of the developing roller shaft 28, the drum shaft engaging portion 34 can be reliably moved to the left side. An urging force toward the direction can be generated.
(4) Also, according to this process cartridge 3, as shown in FIGS. 3 and 7, when the cover 31 is attached to the casing 21, the drum shaft engaging portion 34 can move the right end portion of the drum shaft 15. The drum shaft fitting hole 40 to accommodate is provided.

Therefore, when the cover 31 is mounted on the casing 21, the contact portion 41 of the drum shaft engaging portion 34 can be applied to the right end portion of the developing roller shaft 28 while accommodating the right end portion of the drum shaft 15.
(5) According to the process cartridge 3, as shown in FIGS. 6 and 7, the drum shaft engaging portion 34 is exposed to the outside of the casing 21 when the cover 31 is attached to the casing 21. ing.

Therefore, the contact portion 41 of the drum shaft engaging portion 34 can be visually recognized, and the contact portion 41 of the drum shaft engaging portion 34 can be reliably acted on the right end portion of the developing roller shaft 28.
(6) Also, according to the process cartridge 3, as shown in FIG. 9, when the drum shaft engaging portion 34 reduces the pressure contact force between the photosensitive drum 5 and the developing roller 7, the left end portion of the photosensitive drum 5 is used. And the left end of the developing roller 7 are in contact with each other.

Therefore, with the portion where the left end portion of the photosensitive drum 5 and the left end portion of the developing roller 7 are in contact with each other as a fulcrum, the drum shaft is resisted against the pressure contact force between the photosensitive drum 5 and the developing roller 7 with a smaller force. The engaging portion 34 can reduce the pressure contact force between the photosensitive drum 5 and the developing roller 7.
As a result, the pressure contact force between the photosensitive drum 5 and the developing roller 7 can be reduced more easily.
(7) Further, according to the process cartridge 3, the developing roller 7 includes the coating layer 29 having elasticity, and the left end portion of the photosensitive drum 5 and the left end portion of the developing roller 7 are outside the image forming area. Is touching.

For this reason, it is possible to easily reduce the pressure contact force between the photosensitive drum 5 and the developing roller 7 at both ends in the left and right direction as compared with the case where the pressure contact force between the photosensitive drum 5 and the developing roller 7 is reduced. It is possible to prevent a pressure contact mark or the like from occurring inside.
(8) Further, according to the process cartridge 3, the drum shaft engaging portion 34 is provided integrally with the cover 31 as shown in FIG. 3.

Therefore, the number of parts can be reduced without providing the drum shaft engaging portion 34 separately from the cover 31.
(9) Also, according to this process cartridge 3, as shown in FIGS. 3 and 8, the drum shaft engaging portion 34 is used to maintain a reduction in the pressure contact force between the photosensitive drum 5 and the developing roller 7. A contact portion 41 is provided.

Therefore, if the contact portion 41 is applied to the right end portion of the developing roller shaft 28, the reduction of the pressure contact force between the photosensitive drum 5 and the developing roller 7 can be reliably maintained.
(10) Also, according to this process cartridge 3, as shown in FIG. 2, the casing 21 has a coupling cover 25 to which driving force is input from the main casing 2 and a drum coupling female member 30 ( And the cover 31 has a coupling engagement that covers the coupling cover 25 and the drum coupling female member 30 (drive receiving portion) when the cover 31 is attached to the casing 21 at the left end. A portion 33 is provided.

Therefore, when the cover 31 is attached, not only the photosensitive drum 5 but also the coupling cover 25 and the drum coupling female member 30 (drive receiving portion) can be protected by the coupling engaging portion 33.
(11) Also, according to this process cartridge 3, as shown in FIGS. 6 and 7, after the attachment of the cover 31 to the process cartridge 3 is completed, the left end of the developing roller shaft 28 is shown in FIG. The contact force between the developing roller 7 and the photosensitive drum 5 can be reduced by bringing the contact portion and the contact portion 41 of the cover 31 into contact.

Therefore, when the process cartridge 3 is shipped from the factory, the cover 31 is attached to the process cartridge 3, and the pressure contact force between the developing roller 7 and the photosensitive drum 5 is reduced, so that the photosensitive drum 5 can be reliably protected.
Further, when the used process cartridge 3 is collected from the user, the cover 31 can be attached to the process cartridge 3 without reducing the pressure contact force between the developing roller 7 and the photosensitive drum 5.

Therefore, the user can easily attach the cover 31 to the process cartridge 3 as compared with the case where the cover 31 is attached to the process cartridge 3 while reducing the pressure contact force between the developing roller 7 and the photosensitive drum 5. .
As a result, when the process cartridge 3 is shipped from the factory, the photosensitive drum 5 can be reliably protected, and when the process cartridge 3 is collected from the user, the operation of mounting the cover 31 by the user can be simplified.
5. In the above-described embodiment, the drum shaft engaging portion 34 is provided with the contact portion 41, and the drum shaft engaging portion 34 acts as a pressure contact force reducing member. However, as shown in FIGS. The contact portion 51 may be provided in the coupling engagement portion 33, and the coupling engagement portion 33 may be used as a pressure contact force reducing member. 10-13, the same code | symbol is attached | subjected to the member similar to above-described embodiment, and the description is abbreviate | omitted.
(1) Details of Cover As shown in FIGS. 10 and 11, the cover 31 of the modified example is not provided with the contact portion 41 in the drum shaft engagement portion 34, and is in contact with the coupling engagement portion 33. The cover 51 is formed in the same manner as the cover 31 of the above embodiment except that the portion 51 is provided.

The contact portion 51 is provided over the entire left and right direction of the coupling covering portion 38 so as to protrude upward from the upper end edge of the coupling covering portion 38, and is formed in a substantially prismatic shape.
(2) Attaching the cover In order to attach the cover 31 of the modified example to the process cartridge 3, first, the coupling engagement portion of the cover 31 is fitted to the coupling cover 25 of the process cartridge 3 in the same manner as the above-described embodiment. 33 is engaged.

At this time, the left end portion of the developing roller shaft 28 is pressed upward, the right end portion of the developing roller shaft 28 is used as a fulcrum, and the left end portion of the developing roller shaft 28 is moved upward while coupling is engaged with the coupling cover 25. The part 33 is engaged.
When the pressure on the left end portion of the developing roller shaft 28 is released, the left end portion of the developing roller shaft 28 is brought into contact with the contact portion 51 of the coupling engaging portion 33 from above, and the upward movement is maintained. Is done.

Thus, as shown in FIG. 13, the developing roller 7 is separated from the photosensitive drum 5 at the left end against the pressure contact force against the photosensitive drum 5 while being pressed against the photosensitive drum 5 at the right end. The abutment portion 51 of the coupling engagement portion 33 holds the separation.
That is, the pressure contact force between the developing roller 7 and the photosensitive drum 5 is reduced in the longitudinal direction, and the reduction of the pressure contact force is maintained by the contact portion 51 of the coupling engagement portion 33.

Next, as in the above-described embodiment, the drum shaft engaging portion 34 is engaged with the right end portion of the drum shaft 15 as shown in FIG.
Thereby, as shown in FIG. 10, the attachment of the cover 31 of the modified example to the process cartridge is completed.
(3) Function and effect Also in the modification, the same function and effect as the above-described embodiment can be obtained.

2 Main body casing 3 Process cartridge 5 Photosensitive drum 7 Developing roller 21 Casing 25 Coupling cover 30 Drum coupling female member 31 Cover 33 Coupling engaging portion 34 Drum shaft engaging portion 38 Coupling covering portion 40 Drum shaft fitting hole 41 Contact part 51 Contact part

Claims (9)

A process cartridge that is detachable from the image forming apparatus main body,
An image carrier on which an electrostatic latent image is formed;
It is configured to be able to carry a developer, and is configured to be movable between a pressure contact position that is pressed against the image carrier and capable of supplying the developer to the image carrier, and a separated position that is separated from the image carrier. A developer carrying member,
A casing for accommodating the image carrier and the developer carrier so as to be capable of contacting and separating;
A cover attached to the casing so as to cover the image carrier when the process cartridge is detached from the image forming apparatus main body;
Provided only on one end portion of the cover in the longitudinal direction of the image bearing member, and an elastic deformable pressing force reducing member for reducing the contact pressure of the image bearing member and said developer carrying member,
When the cover is mounted on the casing, the pressure-contact-force reducing member overlaps with the one end portion in the longitudinal direction of the developer carrying member when projected in the longitudinal direction, and extends toward the other side in the longitudinal direction. A process cartridge having an urging force . When the cover is mounted on the casing, the pressure-contact-force reducing member is elastically deformed by being pressed to one side in the longitudinal direction by the one end portion in the longitudinal direction of the developer carrier. The process cartridge according to claim 1, wherein the process cartridge is characterized. The contact pressure reduction member, characterized in that the cover is provided with an accommodating portion for accommodating the one longitudinal end of said image bearing member when mounted in said casing, according to claim 1 or 2 Process cartridge. The contact force reducing member, when said cover is mounted on the casing, characterized in that it is exposed to the outside of the casing, the process cartridge according to any one of claims 1 to 3. When the pressure contact force reducing member reduces the pressure contact force between the image carrier and the developer carrier, the other longitudinal end of the image carrier and the other longitudinal end of the developer carrier the parts, characterized in that it is in contact, the process cartridge according to any one of claims 1 to 4. The developer carrier has elasticity,
The process according to claim 5 , wherein the other end portion in the longitudinal direction of the image carrier and the other end portion in the longitudinal direction of the developer carrier are in contact with each other outside the image forming region. cartridge. The contact pressure reduction member may be provided integrally with the cover, process cartridge according to any one of claims 1 to 6. The contact force reducing member is characterized by comprising a holding portion for maintaining the reduced contact pressure between the developer carrying member and said image bearing member, any one of claims 1 to 7 The process cartridge according to the item . The casing includes a drive receiving portion to which a driving force is input from the image forming apparatus main body at the other end in the longitudinal direction,
9. The cover according to claim 1, wherein the cover includes a covering portion that covers the drive receiving portion when the cover is attached to the casing at the other end portion in the longitudinal direction . The process cartridge as described in any one of Claims .

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