JP2005172906A - Process cartridge and electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process cartridge capable of surely performing operation for separating an electrophotographic photoreceptor drum and a developing member with good responsiveness while securing stroke amount required for separation by reducing the deformation of a frame body, and capable of separating both of them with simple constitution, and to provide an electrophotographic image forming apparatus. <P>SOLUTION: A boss for stopping the rotation of a cartridge, a developing pressure spring and a force receiving part for receiving separating force from a main body are arranged on the same radius from the center of turning where a developing unit is turnably supported in a cleaning unit. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a process cartridge and an electrophotographic image forming apparatus using the same. In particular, it is suitable for application to a color electrophotographic image forming apparatus.

  Here, the electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming system. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc.), a facsimile apparatus, a word processor, and the like.

  The process cartridge is a cartridge in which a charging unit, a developing unit or a cleaning unit and an electrophotographic photosensitive drum are integrally formed, and the cartridge can be attached to and detached from the main body of the electrophotographic image forming apparatus. In addition, at least one of the charging unit, the developing unit, and the cleaning unit and the electrophotographic photosensitive drum are integrally formed into a cartridge that can be attached to and detached from the main body of the electrophotographic image forming apparatus. Further, it means that at least the developing means and the electrophotographic photosensitive drum are integrated into a cartridge so that it can be attached to and detached from the main body of the electrophotographic image forming apparatus.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus using an electrophotographic image process, an electrophotographic photosensitive drum and process means acting on the electrophotographic photosensitive drum are integrally formed into a cartridge, and the cartridge is electrophotographic image forming apparatus. A process cartridge system that is detachable from the main body is employed. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be remarkably improved. Therefore, this process cartridge system is widely used in electrophotographic image forming apparatuses.

  In an image forming apparatus, light corresponding to image information such as a laser, an LED, or a lamp is irradiated to an electrophotographic photosensitive drum (hereinafter simply referred to as a photosensitive drum). As a result, an electrostatic latent image is formed on the photosensitive drum. The electrostatic latent image is developed by a developing device. Further, the developed image formed on the photosensitive drum is transferred to a recording medium. Thereby, an image is formed on the recording medium.

  The image forming apparatus using the process cartridge described above includes an in-line type color electrophotographic image forming apparatus 100 in which a plurality of process cartridges are arranged in a line as shown in FIG. As the developing means of such a process cartridge, the following two configurations are generally known. (1) A contact development method in which development is performed in a state where the developing member is in contact with the photosensitive drum, and (2) a non-contact development method in which development is performed in a state where a predetermined gap is provided between the development member and the photosensitive drum is there. In either method, the developing member and the photosensitive drum during image formation are in a state where the developing member is urged against the photosensitive drum in order to maintain a predetermined contact pressure or gap.

  Here, in the contact developing type cartridge, the developing member is biased to the photosensitive drum. That is, the elastic layer of the developing member is in contact with the photosensitive drum with a predetermined contact pressure. Therefore, the elastic layer of the developing roller may be permanently deformed when the process cartridge is not used for a long time with the process cartridge mounted on the image forming apparatus main body. As a result, image unevenness may occur during development.

  When no bias is applied to the developing roller during non-operation (non-image formation), the toner on the developing roller adheres to the photosensitive drum. The toner may contaminate the recording medium.

  In order to solve the above problem, there has been proposed a process cartridge and an image forming apparatus provided with a mechanism for separating the photosensitive drum and the developing member when the image forming operation is not performed (for example, (See Patent Document 1 and Patent Document 2.) As another configuration, the entire developing unit has a suspension structure that is swingably supported with respect to the photosensitive unit, and shafts that fit into holes provided in bearing members attached to both ends of the developing unit, respectively. Is pivotably coupled to the photoreceptor unit. The developing unit is always urged by a spring, which is an elastic member, so that the developing roller comes into contact with the photosensitive drum by a rotational moment about the axis. Further, the toner container of the developing unit is integrally provided with a protrusion-shaped force receiving portion for contacting a separating means provided in the apparatus main body when the developing roller is separated from the photosensitive drum. . Further, there is a type in which the developing roller is separated from the photosensitive drum by a predetermined gap by pushing up the force receiving portion by a separating means provided in the apparatus main body.

In addition, in the separation configuration described above, the process cartridge assembly is completed in order to avoid a decrease in the separation force receiving portion position accuracy due to variations in single component accuracy of the separation force receiving portion (protrusion shape) and welding and bonding accuracy of the toner container and developer container. Alternatively, there is a type in which molding processing is performed in a unit state during assembly to achieve high accuracy of the position of the separation force receiving portion with respect to the positioning of the process cartridge to the image forming apparatus main body, and to stabilize the separation mechanism.
Patent No. 2900530 (page 2-3, Fig. 1-2) JP 2001-337511 A (pages 5-6, FIG. 2)

  However, in the separation mechanism as described above, the accuracy of individual parts and the accuracy of connecting parts of toner containers and developing containers vary, and large containers (developing containers, toner containers, etc.) are provided with space-restricted and functionally reinforced shapes. The separation stroke is caused by the fact that deformation such as torsion and bending occurs due to the force received from the image forming apparatus at the time of separation, and the component tolerance from the cartridge positioning portion to the separation force receiving portion on the image forming apparatus main body is increased. The required separation could not be guaranteed unless a large value was taken.

  In a situation where further improvement in the responsiveness of the separation operation is required as the speed of the printer is increased, it is a concern for improving the responsiveness of the separation operation that the separation stroke must be made large. It was.

  In addition, the precision of parts generated to improve the separation accuracy accompanying the increase in speed, and the workability and cost increase due to the need for post-processing are also incurred.

  A process comprising at least an electrophotographic photosensitive drum and developing means for developing an electrostatic latent image formed on the electrophotographic photosensitive drum, which is detachable from the main body of the first electrophotographic image forming apparatus of the present invention. In the cartridge, a first frame having the electrophotographic photosensitive drum and a second frame supporting the developing means for developing the electrostatic latent image formed on the electrophotographic photosensitive drum using a developer. A first frame body and a second frame so as to press the developing means against the electrophotographic photosensitive drum. An elastic member that exerts a pressing force with the body, a rotation stopper for preventing the first frame body from rotating within the image forming apparatus body, and the second frame body serving as the electrophotographic image. In the main body of the forming device A force receiving portion for receiving a force from the electrophotographic image forming apparatus main body for separating the developing means and the electrophotographic photosensitive drum, and the force receiving portion, the elastic member, and the rotation stopper The part is a process cartridge disposed on substantially the same radius from the coupling means.

In the electrophotographic image forming apparatus for forming an image on a recording medium, the fourth process cartridge of the present invention is detachable from the main body of the electrophotographic image forming apparatus.
(A) a first frame having the electrophotographic photosensitive drum, and a second frame for supporting the developing means for developing the electrostatic latent image formed on the electrophotographic photosensitive drum using a developer. A first frame body and a second frame so as to press the developing means against the electrophotographic photosensitive drum. An elastic member that exerts a pressing force with the body, a rotation stopper for preventing the first frame body from rotating within the image forming apparatus body, and the second frame body serving as the electrophotographic image. A force receiving portion for receiving a force from the electrophotographic image forming apparatus main body for separating the developing means and the electrophotographic photosensitive drum at a time other than image formation in the main body of the forming apparatus. And the elastic member and the rotation stopper are substantially the same from the coupling means. A mounting portion for detachably mounting the placed process cartridge diameter upper,
(B) An electrophotographic image forming apparatus including: a force applying unit that applies a force necessary for separation to the force receiving unit; and a rotation stopping support unit that supports the rotation stopping unit.

  According to the present invention, the stroke amount necessary for the separation can be reliably operated with good responsiveness by reducing the deformation of the frame in the operation of separating the electrophotographic photosensitive drum from the developing member. Further, the two can be separated by a simple configuration.

  Embodiments of a process cartridge and a color electrophotographic image forming apparatus according to the present invention will be described with reference to FIGS.

(Overall configuration of image forming apparatus)
First, the overall configuration of the image forming apparatus will be described with reference to FIG. The image forming apparatus 100 shown in FIG. 1 has four process cartridge mounting portions (not shown) arranged in parallel in the vertical direction. Each of the cartridges 7 mounted on the mounting portion includes one electrophotographic photosensitive drum (1a to 1d). The photosensitive drum 1 is rotatably supported by a cleaning frame 51 serving as a first frame, and is driven to rotate counterclockwise in the drawing by a driving unit (not shown). Around the photosensitive drum 1, the following components are arranged in order according to the rotation direction. A charging unit (2a to 2d) for uniformly charging the surface of the photosensitive drum 1, a scanner unit (3a to 3d) for forming an electrostatic latent image on the photosensitive drum 1 by irradiating a laser beam based on image information, the static unit A developing unit (4a to 4d) as a second frame for developing the electrostatic latent image using toner as a developer; an electrostatic transfer means 5 for transferring the toner image on the photosensitive drum 1 to the recording medium S; Cleaning members (6a to 6d) for removing toner remaining on the surface of the photosensitive drum 1 after the transfer are disposed. Here, the photosensitive drum 1, the charging unit 2, the developing unit 4, and the cleaning unit 50 are integrated into a cartridge to form a process cartridge 7.

  The photosensitive drum 1 is obtained by coating an organic photoconductive layer (OPC photosensitive member) on the outer peripheral surface of an aluminum cylinder having a diameter of 30 mm, for example. Both ends of the photosensitive drum 1 are rotatably supported by support members. A driving force from a driving motor (not shown) is transmitted to one end. As a result, the photosensitive drum 1 is driven to rotate counterclockwise. As the charging means 2, a contact charging type as shown in FIG. 2 is used. The charging member is a conductive roller formed in a roller shape, and this roller is brought into contact with the surface of the photosensitive drum 1. Then, a charging bias voltage is applied to this roller. As a result, the surface of the photosensitive drum 1 is uniformly charged.

  The scanner unit 3 is arranged in a substantially horizontal direction of the photosensitive drum 1. Then, image light corresponding to an image signal is irradiated to polygon mirrors 9a to 9d rotated by a scanner motor (not shown) by a laser diode (not shown). The image light reflected by the mirror 9 selectively exposes the charged surface of the photosensitive drum 1 through the imaging lenses 10a to 10d. Thereby, an electrostatic latent image corresponding to the image signal is formed. Further, the unit 3 is longer than the pitch between the left and right side plates in the longitudinal direction as shown in FIG. Therefore, the protrusion 33 protrudes outward from the opening holes 35 a to 35 h of the left and right side plates 32. At that time, the scanner unit 3 is pressed by the compression spring 36 about 45 ° downward indicated by an arrow with a force of about 9.8 N. As a result, the scanner unit 3 is reliably pressed against the abutment and positioned.

  As shown in FIG. 2, the developing unit 4 includes a toner container 41a containing yellow toner, a toner container 41b containing magenta toner, a toner container 41c containing cyan toner, and a black toner container. A toner container 41d containing toner and a developing frame 45 are provided. The toner is fed into the toner supply roller 43 by the toner transport mechanism 42 in the toner container 41. Then, toner is applied to the outer periphery of the developing roller 40 by the roller 43 and the developing blade 44 pressed against the outer periphery of the developing roller 40 as a developing member. In addition, the toner is charged. Then, a latent image formed on the photosensitive drum 1 is developed by applying a developing bias to the developing roller 40. The developing roller 40 is disposed to face the photosensitive drum 1.

  On the other hand, as shown in FIG. 1, the image forming apparatus is provided with an electrostatic transfer belt 11 that circulates and moves so as to face and contact all the photosensitive drums 1a to 1d. The transfer belt 11 is a film-like member having a volume resistivity of 10 ^ 11 to 10 ^ 14 Ω · cm and a thickness of about 150 μm. Then, the recording medium S is conveyed to the transfer position by the transfer belt 11 and the toner image on the photosensitive drum 1 is transferred.

  Transfer rollers 12a to 12d are arranged in parallel at positions facing the inside of the transfer belt 11 and facing the four photosensitive drums 1a to 1d. A positive charge is applied from the transfer roller 12 to the recording medium S via the transfer belt 11. As a result, the toner image on the photosensitive drum 1 is transferred to the recording medium S. The transfer belt 11 is stretched and rotated by four rollers including a driving roller 13, driven rollers 14a and 14b, and a tension roller 15 (in the direction of the arrow in FIG. 1). As a result, the transfer belt 11 circulates and the toner image is transferred while the recording medium S is conveyed from the driven roller 14a side to the drive roller 13 side.

  The feeding unit 16 feeds and transports the recording medium S to the image forming unit. A plurality of recording media S are stored in the feeding cassette 17. At the time of image formation, the feeding roller 18 and the registration roller pair 19 are driven and rotated according to the image forming operation. Thus, the recording medium S in the cassette 17 is separated and fed one by one. The leading edge of the recording medium S hits the roller pair 19 and stops temporarily. The recording medium S is fed to the transfer belt 11 by a pair of registration rollers 19 in synchronization with the rotation of the transfer belt 11 and the toner image.

  The fixing unit 20 fixes the toner images of a plurality of colors transferred to the recording medium S. The heating roller 21a rotates, and a pressure roller 21b that applies pressure and heat to the recording medium S in pressure contact therewith. That is, the recording medium S to which the toner image on the photosensitive drum 1 is transferred is conveyed by the fixing roller pair 21 when passing through the fixing unit 20. Then, heat and pressure are applied by the fixing roller pair 21. As a result, the toner images of a plurality of colors are fixed on the surface of the recording medium S.

  The image forming operation is as follows. First, the cartridges 7a to 7d are sequentially driven in accordance with the image formation timing. Then, the photosensitive drums 1a to 1d are rotationally driven according to the drive. Then, the scanner units 3 corresponding to the respective cartridges 7 are sequentially driven. By this driving, the charging unit 2 applies a uniform charge to the peripheral surface of the photosensitive drum 1. The unit 3 exposes the circumferential surface of the photosensitive drum 1 in accordance with an image signal to form an electrostatic latent image on the photosensitive drum 1. The developing roller 40 develops the electrostatic latent image.

  As described above, the toner images on the photosensitive drums 1 are sequentially transferred onto the recording medium S by the electric field formed between the photosensitive drums 1 and the transfer rollers 12. The recording medium S to which the four color toner images are transferred is separated from the transfer belt 11 by the curvature of the driving roller 13. Then, it is carried into the fixing unit 20. After the toner image is heat-fixed by the fixing unit 20, the recording medium S is discharged from the discharge unit 24 to the outside of the main body by the discharge roller pair 23.

(Process cartridge)
Next, a process cartridge embodying the present invention will be described with reference to FIGS. FIG. 2 is a main cross section of the cartridge 7 containing the toner. The cartridge 7a containing yellow toner, the cartridge 7b containing magenta toner, the cartridge 7c containing cyan toner, and the cartridge 7d containing black toner have the same configuration.

  The cartridge 7 (7a to 7d) includes a cleaning unit 50 as a first frame including the photosensitive drum 1 (1a to 1d), the charging unit 2 (2a to 2d), and the cleaning member 6 (6a to 6d). (50a to 50d) and a developing unit 4 (4a to 4d) as a second frame having developing means.

  In the cleaning unit 50, the photosensitive drum 1 is rotatably attached to the cleaning frame 51 via bearings 64 and 65 (see FIG. 8). As described above, the charging unit 2 and the cleaning member 6 are disposed on the circumference of the photosensitive drum 1. Further, the residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 is sent by a toner feeding mechanism 52 to a removed toner chamber 53 provided at the rear of the cleaning frame.

  Then, as shown in FIG. 3, the driving force of a driving motor (not shown) is transmitted to the cleaning unit 50 through the coupling member 70, so that the photosensitive drum 1 is rotationally driven according to the image forming operation. Further, the cleaning frame 51 is provided with a cartridge rotation stopper 51a as a main body positioning boss for preventing the process cartridge from rotating due to its own weight or a moment due to a driving force within the main body of the image forming apparatus. The cleaning frame 51 is provided with a shutter member 72 for protecting the photosensitive drum and a shutter receiving member 73 for opening and closing the shutter member by a link operation.

  Next, as shown in FIGS. 4 and 5, the development unit 4 transmits the drive from the drive motor to the development drive gear 71 and transmits the drive to the development roller 40 through a drive train (not shown). The developing roller 40 is rotatably supported by the developing frame 45 via a bearing member. Further, as described above, the toner supply roller 43 and the developing blade 44 are arranged on the circumference of the developing roller 40. Further, in the toner container 41, a toner transport mechanism 42 for stirring the stored toner and transporting it to the roller 43 is provided.

  The developing unit 4 has a hanging structure in which the entire developing unit 4 is rotatably supported with respect to the cleaning unit 50. That is, the developing unit 4 is provided with holes 47a and 48a which are provided in bearing members 47 and 48 attached to both ends of the unit 4, respectively. The shafts are fitted into the cleaning frame 51 in the holes. 62 and 63 are inserted, and the developing unit 4 is rotatably attached to the cleaning unit 50. In the cartridge 7 alone state (state not attached to the printer main body), the developing unit 4 is pressed so that the developing roller 40 comes into contact with the photosensitive drum 1 by the rotation moment about the shafts 62 and 63. . A pressing spring 54 is provided on the bearing member 47 side, which is the rotation stop portion side, as an elastic member for pressing, and a tension spring 90 (see FIG. 7) as a pressure member is provided on the bearing member 48 side. 4 is arranged. In this embodiment, the pressing spring 54 always biases the developing unit 4 by the pressing member. Further, the bearing members 47 and 48 are integrally provided with force receiving portions 47b and 48b for contacting the separating means (force applying member 8) of the apparatus main body 100 when the developing roller 40 is separated from the photosensitive drum 1. It has been.

  Then, as shown in FIG. 6, the rotation stop portion 51a, the pressing spring 54, and the force receiving portion 47b are disposed on substantially the same radius R around the shafts 62 and 63 serving as the rotation centers. As a result, when the developing roller 40 is separated from the photosensitive drum 1, the force F1 of the force receiving portion 47b receiving the force around the rotation center and the force F2 received by the pressing member 54 are applied to the rotation stopping portion 51a. By arranging them on the same radius, the moment generated around the rotation stopper 51a can be reduced. As a result, it is possible to prevent the cleaning frame 51 from being twisted or deformed around the rotation stopper 51a.

  Here, as shown in FIG. 7, the holes 47a and 48a that are the rotation centers are between the developing roller 40 and the force receiving portions 47b and 48b with respect to the mounting direction in which the cartridge is mounted in the apparatus main body. It is arrange | positioned rather than the mounting direction rather than. With such an arrangement, the force receiving member 47b, 48b rides on the force applying member 8 provided in the apparatus main body when the process cartridge is mounted, so that it is always separated from the inside of the main body with an easy configuration. Can be maintained. When the force applying member 8 is pushed down, the developing roller 40 is pressed against the photosensitive drum 1 by the force of the pressing spring 54 and the pressing spring 90. Further, when the separation is performed again, the developing roller 40 is separated from the photosensitive drum 1 by a predetermined gap by pushing up the force receiving portions 47b and 48b.

  In the contact development method in which development is performed by contacting the photosensitive drum 1 and the developing roller 40, it is preferable that the photosensitive drum 1 is a rigid body and the developing roller 40 is a roller having an elastic body. As this elastic body, a solid rubber single layer or a solid rubber layer coated with a resin coating in consideration of charge imparting property to toner is used.

(Separation mechanism between photosensitive drum and developing member in process cartridge)
Next, a separation mechanism when the cartridge 7 is mounted on the apparatus main body 100 will be described with reference to FIGS. As described above, when the cartridge 7 is a single unit, the developing roller 40 as a developing member is always in contact with the photosensitive drum 1 (see FIG. 2). The cartridge 7 is mounted on the apparatus main body 100 by inserting bearings 64 and 65 that support the photosensitive drum 1 along the guide grooves 34a to 34h (see FIG. 7, the direction of the arrow indicates the cartridge 7). Mounting direction). As shown in FIG. 9, the bearings 64 and 65 are pressed against the abutting surfaces 37 and 38 of the guide groove 34 to determine the position of the cartridge 7 with respect to the apparatus main body 100. The method for pressing the cartridge 7 in the printer body is as follows. That is, as shown in FIG. 10, the shaft 39 is crimped to the side plate 32. A torsion coil spring 30 is supported on the shaft 39. The end 30a is fixed in the hole 32a. In the state where the cartridge 7 is not mounted, the spring 30 is restricted in the rotational direction by the bending and raising 32b. When the cartridge 7 is inserted, the spring 30 rotates counterclockwise in the counterclockwise direction. And when it gets over the bearing 64, the bearing 64 is elastically pressed.

  Next, the separating means will be described with reference to FIGS. 1 and 11 to 14. A separating means (force applying member 8) for separating the developing roller 40 from the photosensitive drum 1 against the urging force of the developing unit 4 is disposed on the back side in the insertion direction of the cartridge 7 of the apparatus main body 100. . As separation means, force applying members 8L and 8R for pushing upward force receiving portions 47b and 48b provided in the developing units 4a to 4d of yellow, magenta, cyan, and black are provided. The force applying member 8 is provided so as to be movable in the vertical direction by a stepping motor (not shown). FIG. 11 shows a separation position in which the force applying member 8 is pushed up to lift the force receiving portions 47 b and 48 b to separate the developing roller 40 from the photosensitive drum 1. FIG. 12 shows a developing position in which the force applying member 8 is released from being pushed up and the force applying member 8 is lowered to move away from the force receiving portions 47b and 48b, and the developing roller 40 is brought into contact with the photosensitive drum 1.

  Only when the image is formed, the push-up of the force applying member 8 is released and the developing unit 4 is moved to the developing position. The developing roller 40 comes into contact with the photosensitive drum 1 by the elastic force of the pressing spring 54 and the tension spring 90 by releasing the pushing of the force applying member 8.

  In addition, a rotation support portion 67 that receives the rotation stop portion 51a of the cartridge described above in FIG. 13 is provided in the image forming apparatus main body. The bearings 64 and 65 are positioned on the image forming apparatus main body, and the rotation stopper 51 a is supported by the rotation support 67. Further, the rotation stopper 51a, the pressing spring 54, and the force receiving portion 47b are disposed on the same radius R and at the same time in the photosensitive drum axial direction. Accordingly, it is possible to prevent the cleaning frame 51 from being deformed in the axial direction of the photosensitive drum when receiving a force from the force applying portion 8L from the image forming apparatus main body of the process cartridge 7.

  FIG. 14 is a view of the cartridge 7 as seen from the direction of the arrow X in FIG. In this configuration, force receiving portions 47 b and 48 b are provided on the bearing members 47 and 48 of the cartridge 7. When the force applying member 8 is pushed up and the photosensitive drum 1 and the developing roller 40 are separated from each other, the force applying member 8 simultaneously contacts the force receiving portions 47b and 48b. This prevents the developing roller 40 from being inclined and separated in the longitudinal direction.

  In this embodiment, when the cartridge 7 is mounted on the apparatus main body 100, as shown in FIG. 1, the force applying member 8 corresponding to the cartridges 7 for all colors of yellow, magenta, cyan, and black is pushed up. It is in a state. Accordingly, with the mounting operation of the cartridge 7, the force receiving portions 47b and 48b provided on the developing unit 4 ride on the force applying members 8L and 8R. As a result, the developing roller 40 is separated from the photosensitive drum 1 by a predetermined gap. This separated state is always maintained when the power is turned off and when development is not performed. Accordingly, even when the cartridge 7 is not used for a long time with the cartridge 7 mounted, it is possible to reliably prevent permanent deformation of the developing roller layer that occurs when the developing roller 40 is brought into contact with the photosensitive drum 1 for a long time. it can.

  Next, when the image forming operation is started by the print signal, the push-up of the force applying member 8 is released in accordance with the development operation timing. The force receiving portion 46 and the force applying member 8 are separated from each other. Accordingly, the developing roller 40 comes into contact with the photosensitive drum 1 by the elastic force of the pressing spring 54 and the tension spring 90 and becomes ready for development.

  In the above-described embodiment, the contact development method has been described as an example, but the present invention can also be applied to a non-contact development method. In this case, for example, it is possible to prevent a trace caused by pressing of the spacer roller.

  As described above, the two states of separation and contact between the photosensitive drum and the developing roller can be easily selected, and the frame can be prevented from being deformed at the time of the separation operation, and the responsive separation operation can be performed. . Since the developing roller is brought into contact with the photosensitive drum only at the time of image formation and is otherwise separated, permanent deformation of the roller can be surely prevented. Further, by adopting a configuration in which the separation is released only at the time of image formation, it is possible to prevent the developer from adhering to the photosensitive drum from the developing roller when a bias is not applied to the process cartridge. Therefore, it is possible to reliably prevent the recording paper and the like from being stained with unnecessary developer.

(Example 2)
In the cleaning frame 51 described above in the first embodiment, the cartridge rotation stopper 51a serves as a main body positioning boss for preventing the process cartridge from rotating due to its own weight or a moment due to a driving force within the main body of the image forming apparatus. A pressing spring 54 that presses the developing roller 40 so as to contact the photosensitive drum 1, and a separation unit (force applying member 8) of the image forming apparatus main body 100 when the developing roller 40 is separated from the photosensitive drum 1. It has been described that in the force receiving portion 47b for abutting, they are disposed on substantially the same radius R with the shaft 62 as the center. In this embodiment, as shown in FIG. 15, the direction of the pressing force F <b> 2 by the pressing spring 54 is arranged toward the tangential direction of the radius R. Further, the direction of the force F <b> 1 received at the time of separation from the force applying member 8 is also arranged in the tangential direction of the radius R. By setting the direction in which these forces are applied to the tangential direction of the radius R, it is possible to reduce the force loss around the rotation center and reduce the moment generated around the rotation stopper 51a. As a result, the cleaning frame can be prevented from being twisted and deformed, and the response at the time of separation can be improved.

1 is an overall configuration diagram of a color electrophotographic image forming apparatus according to a first embodiment of the present invention. FIG. 3 is a cross-sectional explanatory view of a process cartridge according to the first embodiment of the present invention. 1 is a perspective view of a process cartridge according to a first embodiment of the present invention. FIG. 2 is a perspective view of a developing unit according to the first embodiment of the present invention. FIG. 2 is a perspective view of a developing unit according to the first embodiment of the present invention. FIG. 3 is a side view of a process cartridge in the image forming apparatus according to the first embodiment of the present invention. It is a side view of the process cartridge of the first embodiment in the present invention. It is a figure explaining the mounting | wearing structure of the cartridge in the apparatus main body of the 1st Example in this invention. It is a figure explaining the mounting | wearing structure of the cartridge in the apparatus main body of the 1st Example in this invention. It is a figure explaining the mounting | wearing structure of the cartridge in the apparatus main body of the 1st Example in this invention. It is a figure explaining the separation operation (separation position) with respect to the photosensitive drum of the developing roller of the first embodiment in the present invention. FIG. 5 is a diagram illustrating a separation operation (development position) of the developing roller according to the first embodiment of the present invention with respect to the photosensitive drum. FIG. 2 is a perspective view of a process cartridge in the image forming apparatus according to the first embodiment of the present invention. It is a figure explaining the other structure of the press member of the photoconductor unit (1st frame) of the 1st Example in this invention, and a developing unit (2nd frame). FIG. 6 is a side view of a process cartridge in an image forming apparatus according to a second embodiment of the present invention.

Explanation of symbols

C contact position S recording medium t developer 1 (1a to 1d) electrophotographic photosensitive drum 2 (2a to 2d) charging means 3 (3a to 3d) scanner unit 4 (4a to 4d) developing unit (second frame)
5 Electrostatic transfer means 6 Cleaning member 7 (7a-7d) Process cartridge 8 (8a-8d) Force applying member (separating means)
DESCRIPTION OF SYMBOLS 11 Electrostatic transfer belt 12a-12d Transfer roller 40 Developing roller (developing member)
41 toner container 44 developing blade 45 developing frame body 47 bearing member 47a hole 47b force receiving portion 48 bearing member 48b force receiving portion 50 cleaning unit (first frame)
51 Cleaning Frame 54 Pressing Spring 64 Bearing 90 Pressurizing Spring (Tension Spring) (Elastic Member)
100 Image forming apparatus

Claims (4)

In a process cartridge that is detachable from an electrophotographic image forming apparatus main body and includes at least an electrophotographic photosensitive drum and a developing unit for developing an electrostatic latent image formed on the electrophotographic photosensitive drum,
A first frame having the electrophotographic photosensitive drum;
A second frame for supporting the developing means for developing the electrostatic latent image formed on the electrophotographic photosensitive drum using a developer;
Coupling means for pivotally coupling the second frame to the first frame;
An elastic member that exerts a pressing force between the first frame and the second frame so as to press the developing means against the electrophotographic photosensitive drum;
A rotation stopper for preventing the first frame from rotating in the image forming apparatus main body;
The second frame body receives a force from the electrophotographic image forming apparatus main body for separating the developing means from the electrophotographic photosensitive drum when the second frame is not in the main body of the electrophotographic image forming apparatus. A receiving part,
The process cartridge according to claim 1, wherein the force receiving portion, the elastic member, and the rotation stopping portion are disposed on substantially the same radius from the coupling means. The process cartridge according to claim 1, wherein the force receiving portion, the elastic member, and the rotation stopping portion are:
A process cartridge, wherein the process cartridge is disposed downstream of the rotation center in the mounting direction in which the process cartridge is mounted in the electrophotographic image forming apparatus main body and on the same side in the photosensitive drum axial direction.   3. The process cartridge according to claim 2, wherein a direction of a force generated by the elastic member and a direction in which the force receiving portion receives a force from the image forming apparatus main body are tangential directions on the same radius from the coupling unit. Process cartridge characterized by. In an electrophotographic image forming apparatus for forming an image on a recording medium, wherein the process cartridge is detachable from the electrophotographic image forming apparatus main body,
(A) a first frame having the electrophotographic photosensitive drum;
A second frame for supporting the developing means for developing the electrostatic latent image formed on the electrophotographic photosensitive drum using a developer;
Coupling means for pivotally coupling the second frame to the first frame;
An elastic member that exerts a pressing force between the first frame and the second frame so as to press the developing means against the electrophotographic photosensitive drum;
A rotation stopper for preventing the first frame from rotating in the image forming apparatus main body;
The second frame body receives a force from the electrophotographic image forming apparatus main body for separating the developing means and the electrophotographic photosensitive drum from the electrophotographic image forming apparatus main body at a time other than image formation. And
A mounting portion for detachably mounting a process cartridge in which the force receiving portion, the elastic member, and the rotation stopping portion are disposed on substantially the same radius from the coupling means;
(B) a force applying unit that applies a force necessary for separation to the force receiving unit;
A rotation stop support part for supporting the rotation stop part;
An electrophotographic image forming apparatus comprising:

Images