CN116243576A - Process cartridge and image forming apparatus - Google Patents

Abstract

The invention provides a process cartridge and image forming apparatus, the process cartridge includes developing frame, drum frame, developing roller and photosensitive drum, the developing roller is rotatably supported on developing frame, the photosensitive drum is rotatably supported on drum frame; the developing frame is provided with a stress bulge, and the stress bulge forces the developing frame to rotate relative to the drum frame after stress and drives the developing roller to be far away from the photosensitive drum; a movable hook is arranged on one side of the stress bulge, and the movable hook is positioned on one side of the stress bulge away from the photosensitive drum; the lower part of the processing box is provided with a movable seat, the movable seat is provided with a concave part, the movable hook is positioned at the concave part, and the stress bulge downwards stretches into the concave part. The processing box can ensure that the movable seat can drive the developing unit to move, so that the photosensitive drum is cleaned, and the printing quality is ensured.

Description

Process cartridge and image forming apparatus

Technical Field

The present invention relates to the field of electrophotographic image forming, and more particularly, to a process cartridge and an image forming apparatus.

Background

An electrophotographic image forming apparatus generally has an image processing unit and a developing unit therein, and develops an electrostatic latent image formed on the image processing unit with a developer such as carbon powder supplied from the developing unit to form a visible image on a medium such as paper. The toner is generally supplied to the developing unit by a process cartridge or the like having a function of accommodating a certain amount of toner, which is detachably mounted to the developing unit in the electrophotographic image forming apparatus.

Referring to fig. 1, a conventional powder cartridge includes a first driving assembly 11, a second driving assembly 12, a developing roller, a stirring frame, a powder feeding roller and a photosensitive drum, the first driving assembly 11 driving the photosensitive drum to rotate, the second driving assembly 12 driving the developing roller, the stirring frame and the powder feeding roller to rotate, and cleaning the photosensitive drum in a printing gap is required for improving the printing quality in the process of printing the developing cartridge in a machine, and since the photosensitive drum and the developing roller are always contacted during printing, and are required to be separated during cleaning. In the state that the process cartridge cleans the photosensitive drum, the clutch 121 in the second driving assembly 12 enables the second driving head 122 to be separated from the driving gear 123, the second driving head 122 in the imaging device continuously drives the second driving head 122 to rotate, and since the driving gear 123 is separated from the second driving head 122, the driving gear 123 stops rotating, and meanwhile, the developing roller, the stirring frame and the powder feeding roller stop rotating, at the moment, the first driving head in the machine continuously drives the first driving head to rotate, so that the photosensitive drum is driven to rotate, and the cleaning of residual powder on the photosensitive drum is realized.

Therefore, during the image forming and cleaning process, the clutch 121 needs to be switched back and forth between a connection position for connecting the driving gear 123 with the second driving head 122 and a disconnection position for disconnecting the driving gear 123 from the second driving head 122, if the clutch 121 is damaged during operation, the second driving head cannot transmit driving force to the developing roller, which may affect the normal use of the machine, and in addition, the switching back and forth of the clutch 121 may reduce the working efficiency of the machine, if the clutch 121 is not moved to a preset position during the switching position, which may affect the transmission of driving force between the second driving head of the machine and the second driving head 122 of the process cartridge. In addition, the structure of the second driving assembly is complex, the assembly difficulty is high, the cost can be increased, and the production efficiency of the processing box can be reduced.

In addition, in order to be convenient for on the position that removes the developing unit to and the photosensitive drum separation when cleaning, install the atress arch on developing frame generally, be provided with in the imaging device and be used for with the removal hook of atress protruding looks block, the below of removal hook is provided with the spring, when the door closure of lid synthetic image forming device, the processing box atress moves down, remove hook and atress protruding mutual interference in vertical direction, the removal hook can downwardly extrusion, after imaging device works, in the imaging device, the removal seat of bulldoze separating mechanism drives the removal hook horizontal left movement to the position that removes hook and atress protruding in vertical direction do not interfere, at this moment, the removal hook is located between atress protruding and the photosensitive drum, thereby during cleaning position, the removal hook can be along horizontal right direction to the atress protruding thrust, make developing roller and photosensitive drum separation.

Because the movable hook can move up and down mainly by means of the spring arranged at the bottom of the movable hook, when the door cover of the imaging equipment is covered, the spring is stressed to be compressed, and after the spring is compressed for many times, the spring is easy to generate certain plastic deformation, so that the free length of the spring cannot be recovered, the movable hook cannot be reset, and the service life of the imaging equipment is shortened. In addition, due to the limitation of the space of the lower surface of the process cartridge and the lower surface of the cartridge bin of the image forming apparatus, the amount of protrusion of the separating member from the lower surface of the powder cartridge is small, the amount of hooking of the separating member and the moving hook is small, and after plastic deformation of the spring, the moving hook moves down, the amount of hooking is smaller, so that the situation that the moving hook cannot catch the stress protrusion is likely to occur, and further the photosensitive drum cannot be cleaned, and the printing quality is affected.

Disclosure of Invention

A first object of the present invention is to provide a process cartridge that ensures that a moving seat can drive a developing unit to move, realizes cleaning of a photosensitive drum, and ensures printing quality.

A second object of the present invention is to provide an image forming apparatus having the above-described process cartridge.

In order to achieve the first object described above, the present invention provides a process cartridge including a developing frame, a drum frame, a developing roller rotatably supported on the developing frame, and a photosensitive drum rotatably supported on the drum frame; the developing frame is provided with a stress bulge, and the stress bulge forces the developing frame to rotate relative to the drum frame after stress and drives the developing roller to be far away from the photosensitive drum; a movable hook is arranged on one side of the stress bulge, and the movable hook is positioned on one side of the stress bulge away from the photosensitive drum; the lower part of the processing box is provided with a movable seat, the movable seat is provided with a concave part, the movable hook is positioned at the concave part, and the stress bulge downwards stretches into the concave part.

According to the scheme, the length of the stress bulge is prolonged to the position of the insertion concave part, the stress bulge can drive the developing frame to move through the thrust exerted by the side wall of the concave part in the movable seat, and meanwhile, as the stress bulge and the movable hook are dislocated in the scheme in the installation process, the problem that the stress bulge and the movable hook interfere to squeeze the spring at the bottom of the movable hook can not occur, and even if the spring is subjected to plastic deformation, the movable hook cannot be reset, and the movable seat can not be influenced to exert acting force to the developing unit through the stress bulge so as to drive the developing unit to move.

Preferably, the stress protrusion is integrally formed with the developing frame.

In a preferred scheme, a mounting plate is arranged at one end, close to the stress protrusion, of the developing frame, and the stress protrusion and the mounting plate are integrally formed.

Therefore, the scheme of integrally forming the stress bulge and the developing frame has few parts and less assembly procedures, can improve the assembly efficiency and reduce the production cost. The scheme of integrally forming the stress bulge and the mounting plate can improve the flexibility of the position setting of the stress bulge.

One preferable scheme is that one end, close to the stress bulge, on the developing frame is provided with a support piece, the stress bulge is located one end of the support piece, the support piece is provided with a chute, the developing frame is provided with a guide post and a support bulge, the chute is matched with the guide post in an inserting way along the axial direction of the developing roller, the guide post is in sliding fit with the chute, the support bulge is located above the guide post, an elastic reset piece is arranged between the support bulge and the support piece, and under the action of the elastic reset piece, the guide post is in butt joint with the top end of the chute.

Therefore, in the scheme that the stress bulge is arranged on the elastic structure, the elastic reset piece is arranged, so that the stress bulge can move, and in the installation process of the processing box, a buffer effect is achieved for collision which can possibly occur, and damage caused by collision can be avoided.

The further scheme is that the included angle between the extending direction of the chute and the vertical direction is an acute angle, and the bottom end of the chute is closer to the stressed protrusion relative to the top end of the chute.

Therefore, the limitation of the extending direction of the sliding groove can ensure that the stress protrusion can move in the direction away from the moving hook when the stress protrusion receives the acting force of the moving hook during the process of the box packaging machine, so that the damage of the stress protrusion caused by the rigid contact of the stress protrusion and the moving hook is avoided.

The further scheme is that the number of the sliding grooves is more than two, and the sliding grooves are arranged in parallel.

In a preferred scheme, a driving assembly is further arranged on the developing frame, and the driving assembly is positioned at one end of the developing roller and drives the developing roller to rotate; the distance between the free end of the force-bearing projection and the axis of the drive assembly is in the range of 8 mm to 15 mm.

Therefore, the distance between the free end of the stress protrusion and the axis of the developing roller is limited, so that the movable hook can extend into the concave part, and the stability of the thrust force borne by the stress protrusion is ensured.

In a preferred embodiment, the plane is parallel to the plane formed by the axis of the developing roller and the vertical extension line; or the plane is parallel to the axis of the developing roller and is disposed obliquely downward.

Therefore, the inclined downward plane can play a guiding role, so that the movable hook can be conveniently guided in the process of the process cartridge loading machine, and the movable hook can smoothly and relatively slide to a position which is not interfered in the vertical direction.

In order to achieve the second object described above, the present invention provides an image forming apparatus including a cartridge housing, a push-and-pull separating mechanism including a moving seat and a moving hook provided on the moving seat at a moving hook position, and the above-described process cartridge detachably mounted in the cartridge housing; the movable seat is provided with a concave part, the movable hook extends upwards from the concave part, and the side wall of the concave part can apply pushing force to the stress bulge to drive the developing roller to be far away from the photosensitive drum.

Drawings

Fig. 1 is a partial view of a conventional process cartridge.

Fig. 2 is a block diagram of a pressing and separating mechanism in the first embodiment of the process cartridge and the image forming apparatus of the present invention.

Fig. 3 is a structural view of the driving end in the first embodiment of the process cartridge of the present invention.

Fig. 4 is a perspective view showing the engaged positions of the pressing and separating mechanism and the first embodiment of the process cartridge of the present invention.

Fig. 5 is a left side view showing the engaged positions of the pressing and separating mechanism and the first embodiment of the process cartridge of the present invention.

Fig. 6 is a structural view of a mounting plate, a support member, a spring, and the like in the second embodiment of the process cartridge of the present invention.

Fig. 7 is a perspective view showing the engaged positions of the pressing and separating mechanism and the second embodiment of the process cartridge of the present invention.

Fig. 8 is a partial enlarged view at a in fig. 7.

The invention is further described below with reference to the drawings and examples.

Detailed Description

Process cartridge and image forming apparatus of first embodiment

Referring to fig. 2 to 5, the image forming apparatus of the present embodiment includes a cartridge housing in which a first transmission head (not shown), a second transmission head (not shown), a driving mechanism (not shown), and a push separation mechanism 10 are provided, and a process cartridge detachably mounted in the cartridge housing, the driving mechanism driving the first transmission head and the second transmission head to rotate simultaneously. The pushing and separating mechanism 10 is located below the process cartridge, the pushing and separating mechanism 10 includes a movable base 101, a movable hook 102 and a spring 103, the movable hook 102 is slidably connected to the movable base 101 and can move in a vertical direction relative to the movable base 101, a recess 104 is formed in the movable base 101, the movable hook 102 protrudes upward from the recess 104, and the spring 103 is connected to a bottom end of the movable hook 102 and can force the movable hook 102 to move upward to the protruding position. In addition, the moving seat 101 can move along the horizontal direction and drive the moving hook 102 to move, the moving hook 102 is positioned on one side of the stress protrusion 6 on the processing box, which is far away from the photosensitive drum 4, the moving seat 101 is positioned at the moving seat, and the moving hook 102 is positioned at the moving hook position.

The process cartridge includes a developing unit 2 and a drum unit 3, the developing unit 2 includes a developing frame 21, a developing roller 22 and a stirring frame 24 rotatably supported on the developing frame 21, and a bottom of one end of the developing frame 21 is provided with a force receiving projection 6. The drum unit 3 includes a drum frame 31, a photosensitive drum 4 rotatably supported on the drum frame 31, and cleaning blades (not shown) mounted on the drum frame 31, both ends of which are supported on the drum frame 31, and blades of which are abutted on the photosensitive drum 4 for cleaning residual powder on the photosensitive drum 4.

The movable hook 102 is located at a side of the force-bearing protrusion 6 away from the photosensitive drum 4, and the force-bearing protrusion 6 can extend downward into the recess 104 of the movable seat 101, and when the movable seat 101 moves, the sidewall 105 of the recess 104 can apply an urging force to the force-bearing protrusion 6 to drive the developing roller 22 away from the photosensitive drum 4, and a distance between the free end 62 of the force-bearing protrusion 6 and the axis of the second driving assembly 5 is in a range of 8 mm to 15 mm. By extending the length of the force-receiving protrusion 6 to the position where the recess 104 is inserted, the force-receiving protrusion 6 can drive the developing frame 21 to move by the pushing force applied by the side wall 105 of the recess 104 in the movable base 101, and at the same time, since the force-receiving protrusion 6 is dislocated with the movable hook 102 when the solution is installed, the problem of interference between the force-receiving protrusion 6 and the movable hook 102 does not occur, and the force-receiving protrusion 6 does not press the movable hook 102 to cause plastic deformation of the spring.

The top of the end of the drum frame 31 away from the force-receiving projection 6 is provided with an elastic member such as a spring (not shown), the first end of the spring is abutted on the drum frame 31, the second end of the spring is abutted on the developing frame 21, the position where the developing frame 21 is hinged to the drum frame 31 is located between the force-receiving projection 6 and the spring in the height direction of the process cartridge, after the force F1 is applied to the force-receiving projection 6 by the moving seat 101 of the push-pull separation mechanism in the image forming apparatus, the developing frame 21 rotates relative to the drum frame 31, the developing roller 22 is separated from the photosensitive drum 4, the developing roller 22 moves to the cleaning position relative to the photosensitive drum 4, and the force of the spring is in a compressed state at this time. The moving seat 101 drives the moving hook 102 to move reversely, after the acting force on the stress protrusion 6 is removed, the spring pushes the developing frame 21 to rotate under the action of the elastic restoring force of the spring, the developing roller 22 is contacted with the photosensitive drum 4, and the developing roller 22 moves to an imaging position relative to the photosensitive drum 4.

One axial end of the photosensitive drum 4 is provided with a first driving assembly 42, the first driving assembly 42 comprises a first driving head 422, the first driving head 422 and the photosensitive drum 4 are coaxially arranged, and the cross section of the first driving head 422 is triangular with a round hole in the center. The first drive assembly 42 is coupled to the first drive head and receives a first drive force transmitted by the first drive head.

One axial end of the stirring frame 24 is provided with a second driving assembly 5, the first driving assembly 42 and the second driving assembly 5 are positioned on the same side of the processing box, and the second driving assembly 5 is connected with the second transmission head and receives a second driving force transmitted by the second transmission head. The developing frame 21 is provided with a mounting plate 25 at one end near the second driving assembly 5, and the stress protrusion 6 and the mounting plate 25 are integrally formed. The mounting plate 25 is provided with a support hole 251, and the second driving assembly 5 is mounted at the support hole 251.

The developing roller gear 222 is sleeved on one axial end of the developing roller 22, the developing roller gear 222 can drive the developing roller 22 to rotate, the second driving assembly 5 comprises a transmission gear 51 and a second driving head 52 which are integrally formed, the cross section of the second driving head 52 is triangular, a round hole is formed in the center of the second driving head 52, the transmission gear 51 and the second driving head 52 are coaxially arranged, the axis of the second driving assembly 5 is parallel to the axis of the developing roller 22, and the transmission gear 51 is meshed with the developing roller gear 222.

In the present embodiment, the side wall 61 of the force-receiving projection 6 facing the moving hook 102 is a plane parallel to the plane formed by the axis of the developing roller 22 and a vertically extending line, i.e., a line extending in the vertical direction. The side wall 61 of the force-receiving projection 6 is provided in a flat surface to avoid interference with the moving hook 102.

After the processing box is installed, the stress bulge 6 stretches into the concave part 104, the stress bulge 6 and the movable hook 102 are arranged in a staggered manner in the vertical direction, and the stress bulge 6 and the movable hook are not interfered with each other.

The working method of the processing box comprises an imaging step and a cleaning step, wherein the imaging step and the cleaning step are alternately carried out in the working process of the processing box.

Imaging step comprising the following steps: the driving mechanism drives the first transmission head and the second transmission head to rotate simultaneously, at this time, the developing roller 22 is in contact with the photosensitive drum 4, the first transmission head drives the first driving component 42 to rotate so as to drive the photosensitive drum 4 to rotate, the second transmission head drives the second driving component 5 to rotate so as to drive the developing roller 22 and the stirring frame 24 to rotate, the stirring frame 24 is used for stirring carbon powder in a powder bin of the developing unit 2, and the developing roller 22 is matched with the photosensitive drum 4 to perform imaging work.

The cleaning step comprises the following steps: the driving mechanism drives the first driving head and the second driving head to rotate simultaneously, at this time, the moving seat 101 in the imaging device drives the moving hook 102 to move rightwards along the horizontal direction, after the side wall 105 opposite to the moving hook 102 in the concave part 104 applies the acting force F1 to the stress bulge 6, the developing frame 21 rotates relative to the drum frame 31, the developing roller 22 is separated from the photosensitive drum 4, the first driving head drives the first driving component 42 to rotate so as to drive the photosensitive drum 4 to rotate, and the second driving head drives the second driving component 5 to rotate so as to drive the developing roller 22 and the stirring frame 24 to rotate, and the cleaning scraper cleans residual powder on the surface of the photosensitive drum 4. The rotation speed of the developing roller 22 in the image forming step is greater than that of the developing roller 22 in the cleaning step, while the rotation speed of the photosensitive drum 4 in the image forming step is greater than that of the photosensitive drum 4 in the cleaning step. The rotation speed of the developing roller 22 in the cleaning step is small, and it can be ensured that the developing roller 22 does not convey the toner outwards when the photosensitive drum 4 is cleaned.

In other embodiments, the second driving assembly 5 is connected to the developing roller 22 through a clutch, and in the cleaning position, the first transmission head drives the photosensitive drum 4 to rotate, and the second driving assembly 5 is separated from the developing roller 22, so that the second transmission head is separated from the developing roller 22, and the developing roller 22 stops rotating.

Process cartridge and image forming apparatus of second embodiment

As a description of a second embodiment of the process cartridge and the image forming apparatus of the present invention, only differences from the first embodiment of the process cartridge and the image forming apparatus described above will be described below.

Referring to fig. 6 to 8, a supporting member 270 is disposed at one end of the developing frame 221 near the second driving assembly 250, a receiving protrusion 260 is disposed at one end of the supporting member 270, a sliding groove 271 is disposed at one end of the supporting member 270 far from the receiving protrusion 260, a guiding column 2211 and a supporting protrusion 2212 are disposed on the developing frame 221, the sliding groove 271 and the guiding column 2211 are in plug-in fit along the axial direction of the developing roller, the guiding column 2211 is in sliding fit with the sliding groove 271, the supporting protrusion 2212 is disposed above the guiding column 2211, a spring 28 serving as an elastic restoring member is disposed between the supporting protrusion 2212 and the supporting member 270, and the guiding column 2211 is abutted against the top end of the sliding groove 271 under the elastic restoring force of the spring 28. The included angle between the extending direction of the sliding groove 271 and the vertical direction is an acute angle, the bottom end of the sliding groove 271 is closer to the stress protrusion 260 relative to the top end of the sliding groove 271, the number of the sliding grooves 271 is two, and the two sliding grooves 271 are arranged in parallel.

In this embodiment, the force-bearing protrusion 260 can move by the arrangement of the spring 28 and the cooperation of the sliding groove 271 and the guiding post 2211, so that the possible collision is buffered during the process of installing the process cartridge, and damage caused by the collision can be avoided.

From the above, in the cleaning step, after the developing roller and the photosensitive drum are separated, the first driving component still drives the photosensitive drum to rotate, and meanwhile, the second driving component still drives the developing roller to rotate, after the cleaning scraper of the drum unit cleans the photosensitive drum, the developing roller moves to an imaging position, namely, the developing roller contacts with the photosensitive drum, and the driving mechanism of the imaging device drives the first driving component and the second driving component to rotate, so that the developing roller and the photosensitive drum are driven to rotate simultaneously, and therefore, the switching process of the cleaning step and the imaging step is simpler and more convenient, and the situation that the connection between the second driving component and the developing roller fails is avoided, so that the driving cannot be transmitted to the rotating mechanism such as the developing roller. And the processing box simplifies the structure of the second driving component, so that the connection structure of the developing roller and the second transmission head is simpler, and the production cost can be greatly reduced. In addition, if the second transmission head is disengaged from the developing roller in the cleaning position, the developing roller stops rotating, and the abrasion of the rubber layer on the developing roller caused by friction between the developing roller and the carbon powder due to the fact that the developing roller always rotates can be avoided. The imaging step and the cleaning step are alternately performed, so that the printing quality can be improved, and when the imaging step and the cleaning step are alternately performed, the developing roller and the second transmission head are always in a connection state. In addition, the side wall of the stress bulge subjected to the thrust of the movable hook is set to be a plane wall or a curved wall with single curvature, so that the problem that the stress bulge interferes with the hook-shaped part of the movable hook to press the bottom spring of the movable hook in the resetting process of the processing box packaging machine and the movable hook is avoided, and even if the spring is subjected to plastic deformation, the movable hook cannot be reset, and the movable seat is not influenced to apply acting force to the developing unit through the stress bulge to drive the developing unit to move.

In addition, the side wall of the stress protrusion subjected to the pushing force of the moving hook can be a single-curvature curved surface which is bent towards one side of the photosensitive drum or an uneven surface. At least one of the guide post and the supporting projection may be integrally formed with the developing frame, or may be provided on a mounting plate at an end portion of the developing frame. The second drive assembly may also be disposed coaxially with the developer roller. The side wall of the force-receiving projection receiving the pushing force of the moving hook may also be a plane parallel to the axis of the developing roller and disposed obliquely downward. The stress protrusion can also be integrally formed with the developing frame. The number and shape of the guide posts and runners can be varied as desired. The number of the driving mechanisms in the printing device may be two, and the two driving mechanisms respectively drive the first transmission head and the second transmission head to rotate. The above-described modifications can also achieve the object of the present invention.

Finally, it should be emphasized that the foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the invention, but rather that various changes and modifications can be made by those skilled in the art without departing from the spirit and principles of the invention, and any modifications, equivalent substitutions, improvements, etc. are intended to be included within the scope of the present invention.

Claims (8)

1. A process cartridge including a developing frame, a drum frame, a developing roller rotatably supported on the developing frame, and a photosensitive drum rotatably supported on the drum frame;

the developing frame is provided with a stress bulge, and the stress bulge forces the developing frame to rotate relative to the drum frame after being stressed and drives the developing roller to be far away from the photosensitive drum;

the method is characterized in that:

a movable hook is arranged on one side of the stress bulge, and the movable hook is positioned on one side of the stress bulge away from the photosensitive drum;

the lower part of the processing box is provided with a movable seat, the movable seat is provided with a concave part, the movable hook is positioned at the concave part, and the stress protrusion extends downwards into the concave part.

2. A process cartridge according to claim 1, wherein:

the stress protrusion and the developing frame are integrally formed.

3. A process cartridge according to claim 1, wherein:

and a mounting plate is arranged at one end, close to the stress protrusion, of the developing frame, and the stress protrusion and the mounting plate are integrally formed.

4. A process cartridge according to any one of claims 1 to 3, wherein:

the developing device comprises a developing frame, and is characterized in that a supporting piece is arranged at one end of the developing frame, which is close to the stress protrusion, a chute is arranged at one end of the supporting piece, a guide post and a supporting protrusion are arranged on the developing frame, the chute is matched with the guide post in an inserting way along the axial direction of the developing roller, the guide post is in sliding fit with the chute, the supporting protrusion is arranged above the guide post, an elastic reset piece is arranged between the supporting protrusion and the supporting piece, and the guide post is in butt joint with the top end of the chute under the action of the elastic reset piece.

5. A process cartridge according to claim 4, wherein:

the contained angle between the extending direction of spout and the vertical direction is the acute angle, the bottom of spout for the top of spout is closer to the atress arch.

6. A process cartridge according to claim 4, wherein:

the number of the sliding grooves is more than two, and a plurality of the sliding grooves are arranged in parallel.

7. A process cartridge according to any one of claims 1 to 3, wherein:

the developing frame is also provided with a driving component which is positioned at one end of the developing roller and drives the developing roller to rotate;

the distance between the free end of the force-bearing protrusion and the axis of the drive assembly is in the range of 8 mm to 15 mm.

8. An image forming apparatus including a cartridge housing, a push-pull separation mechanism including a moving seat and a moving hook provided on the moving seat at the moving hook position, and a process cartridge detachably mounted in the cartridge housing;

the method is characterized in that:

the process cartridge according to any one of claims 1 to 7, wherein the movable seat is provided with a recess, the movable hook protrudes upward from the recess, and a side wall of the recess is adapted to apply an urging force to the force-receiving projection to drive the developing roller away from the photosensitive drum.

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