JP2014119590A - Developing device and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress, with a simple configuration, an image carrier frame and a developer carrier frame from being deformed by a force of urging means during non-use of a process cartridge.SOLUTION: A process cartridge includes an image carrier, an image carrier frame, a developer carrier, a developer carrier frame, urging means for applying an urging force to the image carrier frame and the developer carrier frame, and a moving member that contacts the urging means. The moving member can take a first position to control the magnitude of the urging force of the urging means to be predetermined magnitude, and a second position to reduce the magnitude of the urging force of the urging means smaller than the predetermined magnitude. The process cartridge further includes an engaging part that is engaged with the image carrier frame or the developer carrier frame to hold the position of the moving member at the first position.

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system, a developing device used therefor, and a process cartridge.

  Here, the electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic 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 machine, a word processor, and the like.

  The process cartridge is a cartridge in which a charging unit, a developing unit, a cleaning unit, and an electrophotographic photosensitive member are integrated as a process unit, and the process cartridge can be attached to and detached from the main body of the electrophotographic image forming apparatus. is there.

  The developing device is a device in which developing means used for developing the electrostatic latent image on the electrophotographic photosensitive member is integrated, and constitutes a part of the process cartridge, or the developing device alone is an electrophotographic photosensitive device. It is detachably mounted on an electrophotographic image forming apparatus having a body.

  An image forming apparatus such as a printer using an electrophotographic process uniformly charges a photosensitive drum, which is an image carrier, and forms a latent image by selective exposure to the photosensitive drum. The latent image is developed with toner as a developer, the toner image is transferred to a recording medium, and further, the toner image is fixed on the recording medium by applying heat or pressure to the transferred toner image, thereby forming an image. Record.

  Such an apparatus involves toner replenishment and maintenance of various process means. As a means for facilitating the toner replenishment work and maintenance, there is a process cartridge system in which all or a part of the photosensitive drum, charging means, developing means, cleaning means, etc. are combined into a cartridge. This cartridge is configured to be detachable from the main body of the image forming apparatus. According to this process cartridge system, the user can perform maintenance of the apparatus in the form of replacement of the process cartridge and the developing device, so that the operability can be remarkably improved. For this reason, the process cartridge system is widely used in image forming apparatuses.

  A process cartridge and a developing device include a developing roller that develops an electrostatic latent image formed on a photosensitive drum, a developer supplying roller that supplies toner as a developer to the developing roller, and a developer supplying roller that contains toner. And a developer container having an opening for supplying the developer.

  As described above, the process cartridge type image forming apparatus forms an image on a recording medium using a developer. In the contact development method in which development is performed by bringing a developing roller for supplying a developer to the photosensitive drum in contact with the photosensitive drum, one or more types of resistors having generally higher electric resistance values than the base on a conductive base. A layer is provided and this resistive layer is in contact with the photoreceptor drum. The developing roller uses a material in which conductive powder is dispersed in an elastic material such as rubber so as not to damage the photosensitive drum. Further, in order to stabilize the contact between the developing roller and the photosensitive drum and to make the developable area between the developing roller and the photosensitive drum uniform, the developing roller is constantly applied to the photosensitive drum by a biasing means such as a spring. Pressure (see Patent Document 1).

  Even in a process cartridge that employs a non-contact developing method in which the developing roller is disposed at a predetermined interval on the photosensitive drum, the developing roller is maintained in order to maintain the interval between the developing roller and the photosensitive drum at the predetermined interval. It is urged by the urging means toward the photosensitive drum.

JP2003-241621

  In the above conventional example, in order to urge the developer carrier to the image carrier, the urging means is attached to the developer carrier frame that supports the developer carrier and the image carrier frame that supports the image carrier. The biasing means applies force to both frames. However, when the process cartridge is distributed or stored, the developer carrier and the image carrier may be held apart from each other in order to prevent the image carrier and the developer carrier from being damaged. In this case, the urging means separates the developer carrier from the image carrier against the force urging the image carrier frame and the developer carrier frame, so that the image carrier frame is in contact with the urging means. A large force is applied from the biasing means to the contact portion of the developer carrier frame. At this time, if a large force is applied from the urging means for a long time, the image carrier frame and the developer carrier frame may be deformed. Therefore, conventionally, it is necessary to improve the strength of the contact portions of both frames that come into contact with the urging means, which may lead to an increase in cost.

  In view of the above, an object of the present invention is to suppress the deformation of the process cartridge by the force of the urging means when the process cartridge is not used with a simple configuration.

In order to achieve the above object, a typical configuration according to the present application is as follows.
A process cartridge that can be attached to and detached from the main body of the image forming apparatus,
An image carrier on which a latent image is formed;
An image carrier frame for supporting the image carrier;
A developer carrying member carrying the developer;
A developer carrier frame for supporting the developer carrier;
Biasing means for applying a biasing force for biasing the developer carrier to the image carrier to the image carrier frame and the developer carrier frame;
A moving member that is movably provided on either the image carrier frame or the developer carrier frame, and that contacts the biasing means;
With
The moving member has a first position where the urging force by the urging means has a predetermined magnitude, and the second position that reduces the urging force by the urging means to be less than the predetermined magnitude or eliminates the urging force. And an engaging portion that engages with the image carrier frame or the developer carrier frame to hold the position of the moving member at the first position. And

  According to the present invention, when the process cartridge is not used, the process cartridge can be prevented from being deformed by the force of the urging means with a simple configuration.

Sectional view of the process cartridge when the spring support member in the first embodiment is in the second position (cartridge separation state) Sectional view of the process cartridge when the spring support member in the first embodiment is in the first position (cartridge separation state) The perspective view of the spring support member in a 1st Example The perspective view which shows the whole structure of an electrophotographic image forming apparatus. Sectional drawing which shows the whole structure of an electrophotographic image forming apparatus Sectional view of the process cartridge when the spring support member in the first embodiment is in the first position (cartridge contact state) (A) Image forming apparatus main body insertion direction of developing pressure spring support member moving configuration by image forming apparatus main body regulating member, (b) Top view of developing pressure spring supporting member moving configuration by image forming apparatus main body regulating member Top view of developing pressure spring support member moving configuration by cam (A) Cross-sectional view of the spring support member in the second position when the spring support member is in the cartridge separation state in the first embodiment, (b) The spring support member is in the first position in the cartridge contact state in the first embodiment. Sectional view of spring support member Sectional drawing of the cleaning frame which shows the assembly method of the spring support member in 1st Example, and a development pressurization spring The top view of the process cartridge in the 2nd position with the spring support member in a 2nd Example The top view of the process cartridge in the 2nd Example in which the spring support member is a 1st position FIG. 10 is a top view of a developing pressurizing spring support member moving configuration by an image forming apparatus main body regulating member in the second embodiment. The perspective view of the spring support member in 2nd Example (A) The developing separation spring in the unloaded state in the second embodiment and a partial cross-sectional view of the spring support portion in the second position of the spring support member, (b) the spring support member in the second position of the first position. Partial sectional view of the spring support part in the cartridge (separated cartridge state) The side view of the developing device frame which shows the assembly method of the spring support member in the 2nd example, and a development pressure spring.

<Example 1>
Hereinafter, a process cartridge using the developing device according to the first embodiment of the present invention and an image forming apparatus for mounting the process cartridge to form an image will be described.

  The process cartridge, the process cartridge, and the image forming apparatus to which the process cartridge can be mounted will be described with reference to FIGS. 1 to 15 and FIG. FIG. 1 is a cross-sectional view of the process cartridge when the spring support member in the first embodiment is in the second position. 2 is a cross-sectional view of the process cartridge when the spring support member in the first embodiment is in the first position, and FIG. 3 is a perspective view of the spring support member. 4 is a perspective view showing the overall configuration of the electrophotographic image forming apparatus, FIG. 5 is a cross-sectional view showing the overall configuration of the electrophotographic image forming apparatus, and FIG. 6 is a cross section of the process cartridge at the time of developing contact in the first embodiment. FIG. 7 is a moving configuration of the spring support member using the mounting force, FIG. 8 is a moving configuration of the spring support member using the cam, and FIG. 9 is a sectional view of the spring support member at the first and second positions. 10 is a cross-sectional view showing a method of assembling the spring support member and the development pressure spring. FIG. 11 is a side view of the process cartridge when the spring support member according to the second embodiment is in the second position, and FIG. 12 is a side view of the process cartridge when the spring support member according to the second embodiment is in the first position. It is. FIG. 13 shows the moving configuration of the spring support member using the mounting force in the second embodiment. FIG. 14 is a perspective view of a spring support member in the second embodiment. 15 is a partial sectional view of the developing separation spring in the unloaded state in the second embodiment and the spring support portion in the first and second positions, and FIG. 16 is a spring support member and developing pressure in the second embodiment. It is a side view of the developing device frame showing a method of assembling the spring.

  Here, as an order of description, the overall configuration of the process cartridge and the image forming apparatus using the process cartridge will be described, and then the moving configuration of the spring support member of the present invention will be described.

"overall structure"
An image forming apparatus 100 shown in FIG. 5 is a four-color full-color laser printer using an electrophotographic process, and forms a color image on a recording medium S. The image forming apparatus 100 includes a mounting unit 101 (101a to 101d) (see FIG. 4) that is a mounting unit for four process cartridges arranged side by side with respect to the horizontal direction. Each of the process cartridges 1 (1a to 1d) mounted on the mounting portion 101 includes one electrophotographic photosensitive drum 11 (11a to 11d) (hereinafter referred to as a photosensitive drum). The photosensitive drum 11 is an image carrier on which a latent image (electrostatic latent image) is formed.

  The photosensitive drum 11 is rotationally driven in the arrow Q direction by a driving member (not shown). Further, a laser unit is irradiated with a laser beam based on the image information to form an electrostatic latent image on the photosensitive drum 11, and an intermediate transfer belt to which toner images of four colors on the photosensitive drum 11 are collectively transferred. 110 is arranged. Here, the photosensitive drum 11, the cleaning member 15, the charging roller 12, and the developing unit 20 are integrated into a cartridge to form the process cartridge 1. The process cartridge 1 is detachably mounted on the apparatus main body 100a of the image forming apparatus 100 by a user (see FIG. 4). The apparatus main body 100a refers to a portion of the image forming apparatus 100 excluding the process cartridge 1, and is configured so that the process cartridge can be attached and detached.

  The intermediate transfer belt 110 is stretched around a driving roller 111 and a tension roller 112. Further, primary transfer rollers 113 (113a to 113d) are disposed inside the intermediate transfer belt 110 so as to face the respective photosensitive drums 11 (11a to 11d). Then, a transfer bias is applied to the intermediate transfer belt 110 by bias applying means (not shown).

  The toner image formed on the photoconductive drum 11 rotates in the direction of arrow Q of each photoconductive drum 11, rotates in the direction of arrow R of the intermediate transfer belt 110, and further positively biases the primary transfer roller 113. By the application, primary transfer is sequentially performed on the intermediate transfer belt 110. Then, the four-color toner images are conveyed to the secondary transfer unit 131 in a state where the intermediate transfer belt 110 is overlapped.

  In synchronization with the image forming operation, a sheet S as a recording medium is conveyed by conveying means including a feeding device 120 and a pair of registration rollers 130. The feeding device 120 includes a feeding cassette 121 that stores the sheet S, a feeding roller 122 that feeds the sheet S, and a conveyance roller pair 124 that conveys the fed sheet S. The sheets S stored in the feeding cassette 121 are pressed against the feeding roller 122 and are separated and conveyed one by one by the separation pad 123.

  Then, the sheet S conveyed from the feeding device 120 is conveyed to the secondary transfer unit 131 by the registration roller pair 130. In the secondary transfer unit 131, a positive bias is applied to the secondary transfer roller 132. As a result, the four color toner images on the intermediate transfer belt 110 are secondarily transferred to the conveyed sheet S.

  The fixing unit 140 as a fixing unit applies heat and pressure to the toner image formed on the sheet S and fixes the toner image. The fixing belt 140a has a cylindrical shape and is guided by a belt guide member (not shown) to which heat generating means such as a heater is bonded. The fixing belt 140a and the pressure roller 140d form a fixing nip with a predetermined pressure contact force.

  Then, the sheet S on which the unfixed toner image conveyed from the image forming unit is formed is heated and pressed at the fixing nip between the fixing belt 140a and the pressure roller 140b. Then, the unfixed toner image on the sheet S is fixed on the sheet S. Thereafter, the sheet S on which the toner image is fixed is discharged to the discharge tray 151 by the discharge roller pair 150.

  On the other hand, the toner remaining on the surface of the photosensitive drum 11 after the toner image transfer is removed by the cleaning member 15 (15a to 15d). The removed toner is collected in the removed toner chamber 16a in the photoreceptor unit 10 (10a to 10d) shown in FIG. 4 (see FIG. 6).

  Further, the toner remaining on the intermediate transfer belt 110 after the secondary transfer onto the sheet S is removed by the transfer belt cleaning device 114. The removed toner passes through a waste toner conveyance path (not shown) and is collected in a waste toner collection container (not shown) disposed on the back surface of the apparatus.

<Process cartridge>
FIG. 6 is a main cross section of the process cartridge 1 containing the toner t. The process cartridge 1a containing yellow toner t, the process cartridge 1b containing magenta toner t, the process cartridge 1c containing cyan toner t, and the process cartridge 1d containing black toner t are It is the same configuration.

  The process cartridge 1 includes a photosensitive drum 11, a charging roller (charging unit) 12, and a photosensitive unit (image carrier unit) 10 including a cleaning member (cleaning unit) 15. Further, the process cartridge 1 has a developing unit 20 having a developing roller 21 as a developer carrier. The developing roller 21 is a member that carries a developer (toner t) on its surface and supplies the toner to the photosensitive drum 11 to develop the latent image as a toner image (developer image).

  A photosensitive drum 11 is rotatably attached to a cleaning frame (image carrier frame) 16 of the photosensitive unit 10. Then, by transmitting the driving force of a driving motor (not shown) to the photosensitive unit 10, the photosensitive drum 11 is rotationally driven according to the image forming operation. As described above, the charging roller 12 and the cleaning member 15 are disposed on the circumference of the photosensitive drum 11. Further, the residual toner removed from the surface of the photosensitive drum 11 by the cleaning member 15 falls into the removed toner chamber 16a. A charging roller bearing 13 is attached to the cleaning frame 16 so as to be movable in the direction of arrow D passing through the center of the charging roller 12 and the center of the photosensitive drum 11. A shaft 12j of the charging roller 12 is rotatably attached to the charging roller bearing 13. The charging roller bearing 13 is in a state of being pressed toward the photosensitive drum 11 by the charging roller pressing member 14.

  The developing unit 20 includes a developing roller 21 and a developing frame (developer carrying body frame) 24 that rotate in the direction of arrow B in contact with the photosensitive drum 11. The developing roller 21 is rotatably supported by the developing frame 24 via bearing members 26 (26R, 26L) attached to both sides of the developing frame 24 in the longitudinal direction. A toner supply roller 22 that rotates in the direction of arrow C in contact with the developing roller 21 and a developing blade 23 for regulating the toner layer on the developing roller 21 are disposed on the circumference of the developing roller 21. Further, the toner container 24 a of the developing frame 24 is provided with a toner transport member 25 for stirring the stored toner and transporting the toner to the toner supply roller 22.

  The developing unit 20 is rotatably coupled to the photosensitive unit 10 around a shaft 27 (27R, 27L) fitted in the holes 26Ra, 26La provided in the bearing members 26R, 26L. Here, the developing unit 20 and the photosensitive unit 10 are urged by a developing pressure spring (pressing spring) 28 that is an urging means. Therefore, when the image of the process cartridge 1 is formed, the developing unit 20 rotates about the shaft 27 in the direction of arrow A, and the developing roller 21 is in contact with the photosensitive drum 11.

  Below the developing unit 20, a developing separation portion 30 (30a, 30b) that receives an acting force in the direction of arrow G from the developing separation mechanism 105 of the image forming apparatus 100 is provided. The developing separation portion 30 receives an acting force in the direction of arrow G from the developing separation mechanism 105, thereby rotating the developing unit 20 about the shaft 27 in the direction opposite to the arrow direction A. As a result, the developing roller 21 and the photosensitive drum 11 are kept separated. Further, when the acting force from the developing separation mechanism 105 is released, the contact state is switched.

  In addition, in the transportation / distribution process after the manufacture of the process cartridge is completed until the user completes the mounting of the process cartridge on the main body of the image forming apparatus, the photosensitive drum 11 and the developing roller 21 are separated by a configuration (not shown) such as a drum cover. The separated state is maintained.

  That is, the developing roller 21 is close to the photosensitive drum 11 and develops a latent image formed on the photosensitive drum 11 (operation position: see FIG. 6) and a separated position away from the photosensitive drum 11 (FIG. 1). 2). The developing roller 21 is kept in the separated position when the process cartridge is not used. In this embodiment, since the process cartridge adopts the contact developing method, the developing roller 21 contacts the photosensitive drum 11 when the developing roller 21 is in the operation position.

《Mobile development pressure spring support part configuration》
Next, the details of the configuration of the movable developing pressurizing spring support portion which is the developing pressurizing configuration which is a feature of the present invention will be described.

  1 and 2 are sectional views of a process cartridge having a movable developing pressure spring support member. The moving member (hereinafter referred to as a spring support member) 2 having the first bias receiving portion 31 on the cleaning frame body 16 side is movable from the second position shown in FIG. 1 to the first position shown in FIG. Although the details will be described later, the second position means that the urging force of the developing pressure spring 28 is reduced at the time of transportation / distribution of the process cartridge, storage, etc., so that the process cartridge is not deformed by the force of the developing pressure spring 28. It is a position to do. The first position is a position where the developing pressure spring 28 generates an urging force necessary to position the developing roller 21 at the position where it acts on the photosensitive drum 11.

  In the drawings, the spring support member 2 at the first position is particularly indicated by reference numeral 2b, and the spring support member 2 at the second position is particularly indicated by reference numeral 2a. Further, a second urging receiving portion 32 is formed on the developing frame 24 side.

  As shown in FIG. 10, the spring support member 2 is inserted into the cleaning frame body 16 in the direction of the arrow I as shown in FIG. Part) 8 in the second position. That is, when the second position restricting portion 8 provided on the spring support member 2 is engaged with the cleaning frame body 16, the spring support member 2 is held at the second position. Thereafter, the development pressure spring 28 is attached to the spring support member 2 from the direction of the arrow J, and finally the cleaning frame 16 and the development frame 24 are combined. Here, the developing pressure spring 28 is a compression spring. The spring support member 2 having the movable first urging receiving portion 31 may be configured not on the cleaning frame body 16 side but on the developing frame body 24 side. In this case, the second urging receiving portion 32 is configured on the cleaning frame body 16 side.

  Here, when the spring support member 2 of the development pressure spring as the biasing means is in the first position, the elastic force of the development pressure spring is F1, and the development when the spring support member 2 is in the second position is performed. When the elastic force of the pressure spring is F2, F2 <F1. That is, when the spring support member 2 is in the first position, the force generated by the developing pressure spring 28 has a predetermined magnitude (F1) required to bias the developing roller 21 toward the photosensitive drum 11. . On the other hand, when the spring support member 2 is in the second position, the force generated by the developing pressure spring 28 has a magnitude (F2) smaller than the predetermined magnitude (F1). When the spring support member 2 is in the second position, F2 = 0 may be set and the urging force of the developing pressure spring 28 may be eliminated.

  Compared with the case where the spring support member 2 is in the first position, the load applied to the spring support portions on both sides of the cleaning frame body 16 and the development frame body 24 that supports the development pressure spring 28 is greater when the spring support member 2 is in the second position. Can be reduced. Thereby, it is possible to prevent the deformation | transformation of the spring support part provided in both frame bodies. In other words, in this embodiment, the deformation of the process cartridge 1 is suppressed by setting the spring support member 2 to the second position when the process cartridge is not used (distribution or storage).

  In particular, when the process cartridge 1 is not used (for example, during storage or distribution), the developing roller 21 and the photosensitive drum 11 are separated from each other so that the developing roller 21 and the photosensitive drum 11 are not damaged or deformed. It may be held (see FIG. 1). In this case, since the developing pressure spring 28 is contracted more than when the developing roller 21 and the photosensitive drum 11 are in contact, the force generated by the developing pressure spring 28 increases accordingly. However, when the developing roller 21 and the photosensitive drum 11 are separated from each other, if the spring support member 2 is set to the second position in advance, the developing pressure spring is maintained even if the developing roller 21 and the photosensitive drum 11 are separated from each other. The force applied to the developing frame 24 and the cleaning frame 16 can be suppressed. As a result, the deformation of the developing frame 24 and the cleaning frame 16 due to the force of the developing pressure spring 28 can be suppressed. Further, the free length of the developing pressure spring 28 as the biasing means is 11 and the distance between the spring positioning boss tips in the second position in the process cartridge separation state is 12. At this time, since l2 <l1, the developing pressure spring 28 does not come off during transportation / distribution.

  Next, the process of moving the spring support member 2 from the second position to the first position will be described. When the user mounts the process cartridge on the main body of the image forming apparatus and starts using it, an external force is applied to the acting force receiving portion 9 of the spring support member 2 in the direction of arrow G. At this time, the restriction by the second position restricting portion 8 is removed, and the spring support member 2 fixed at the second position is moved from the second position to the first position, and is provided on the spring support member 2. The first position restricting portion (first engaging portion) 7 fixes the first position. That is, when the first restricting portion is engaged with the cleaning frame body 16, the spring support member 2 is held at the first position. In addition, the snap fit fastener is utilized for the 1st position control part 8 and the 2nd position control part 7 here (refer FIG. 3). When the spring support member 2 moves from the second position to the first position, the length of the development pressure spring 28 is shortened, and the biasing force of the development pressure spring 28 is increased. As a result, the developing unit 20 is urged by the developing pressure spring 28 as urging means, and rotates in the direction of arrow A about the coupling shaft 27 (see FIG. 6). Then, the developing roller 21 contacts the photosensitive drum 11.

  As an external force for moving the spring support member 2, a configuration example is shown in FIG. When the process cartridge 1 is mounted on the mounting portion 101 of the image forming apparatus main body 100, when the spring support member 2 is in the second position, the mounting force is used to move the main body regulating member (action portion) 3 in the direction of the arrow L. Receive action force. At this time, the spring support member 2 moves from the second position to the first position (see FIGS. 7A and 7B). When the process cartridge is completely installed in the image forming apparatus main body, the process cartridge 1 does not interfere with the main body regulating member 3 of the image forming apparatus main body 100.

  In addition, as shown in FIG. 8, after the process cartridge 1 is mounted on the mounting portion 101 of the image forming apparatus 100, a cam (acting portion) 4 provided in the image forming apparatus 100 is rotated so that the acting force receiving portion 9 may be configured to apply an acting force in the direction of the arrow L. That is, as the cam 4 rotates, the spring support member 2 moves from the second position to the first position. Similarly to the above, after the spring support member 2 is moved from the second position to the first position, the cam 4 is rotated again so that it does not interfere with the process cartridge 1.

  As described above, according to the present embodiment, it is possible to reduce the load applied to the spring as the biasing means in the physical distribution process until the process cartridge is mounted on the main body. For this reason, it is possible to suppress deformation of the supporting portion that supports the spring as the biasing member and the developing roller. As a result, the pressure applied by the developing roller to the photosensitive drum is stabilized, and a high-quality image can be obtained.

  In the process cartridge of the present embodiment, when the developing roller 21 develops the latent image on the photosensitive drum 11 (when the developing roller 21 is in an operating position where the developing roller 21 acts on the photosensitive drum 11), the developing roller 21 is the photosensitive drum. 11 is used. However, when the developing roller 21 develops the latent image on the photosensitive drum 11, the present embodiment is applied to a process cartridge that employs a non-contact developing method in which the developing roller 21 maintains a predetermined interval between the photosensitive drums 11. The following configuration may be applied. In the case of a process cartridge that employs a non-contact developing method, when the developing roller 21 is in the working position, a spacer is sandwiched between the developing roller 21 and the photosensitive drum 11, so that the developing roller 21 and the photosensitive drum 11 A predetermined gap is formed between them.

<Example 2>
11 and 12 show top views of the process cartridge in the second embodiment. In the example shown in the figure, a tension spring 29 is used as a development pressure spring instead of the development pressure spring 28 of the compression spring shown in the first embodiment. The spring support member 2 having the first urging receiving portion 33 is attached to the developing frame 24 side. Also in this configuration, the spring support member 2 can move from the second position to the first position, as in the first embodiment.

  Further, as a method of attaching the spring support member 2 to the developing device frame 24, the spring support member 2 is aligned with the groove of the developing device frame 24 as shown in FIG. Insert until the restricting portion 8 is engaged. Thereafter, the cleaning frame 16 and the developing frame 24 are combined. Finally, the tension spring 29 is attached from the direction of the arrow K, and the spring support member 2 is fixed at the second position.

  Here, as in the first embodiment, when the elastic force at the first position of the tension spring 29 as the biasing means is F1, and the elastic force at the second position is F2, F2 <F1. . At this time, the load applied to the spring support portions on both sides of the cleaning frame 16 and the developing frame 24 that support the tension spring 29 in the second position can be reduced as compared with the first position. It is possible to prevent deformation of the support portion.

  Further, the free length of the tension spring 29 as the biasing means is 11 ', and the distance between the spring positioning boss tips in the second position in the process cartridge separated state is 12'. At this time, since l1 ′ <l2 ′, as in the first embodiment, the compression spring 29 does not come off during transportation / distribution.

  Here, FIG. 13 shows a configuration example as an external force for moving the spring support member 2 in the development pressing configuration by the tension spring 29. As in the first embodiment, the user uses the mounting force when the process cartridge is mounted on the main body of the image forming apparatus and starts to be used. An acting force is applied to the acting force receiving portion 9 provided on the spring support member 2 in the direction of arrow M from a regulating member (an acting portion) provided on the main body. Then, the spring support member 2 that has been restricted at the second position by the second position restricting portion 8 that is configured in itself moves from the second position to the first position, and the first position restricting portion 7 Fixed in the first position.

  When the spring support member 2 moves from the second position to the first position, the tension spring 29 extends (becomes longer), so that the urging force by the tension spring 29 increases. Therefore, the developing unit 20 is urged by a tension spring 29 as urging means, and rotates around the coupling shaft 27. As a result, the developing roller 21 comes into contact with the photosensitive drum 11.

  As described above, according to the present embodiment, even when the tension spring is used as the developing pressure spring, the deformation of the supporting portion supporting the spring as the biasing member and the developing roller is suppressed. Can do. As a result, the pressure applied by the developing roller to the photosensitive drum is stabilized, and a high-quality image can be obtained.

DESCRIPTION OF SYMBOLS 1 (1a-1d) Process cartridge 2 Spring support member 2a Spring support member in 2nd position 2b Spring support member in 1st position 3 Main body control member 5 Developer container side positioning boss 7 1st position control part 10 Cleaning Unit 11 (11a to 11d) Photosensitive drum 20 (20a to 20d) Developing unit 21 Developing roller 28 Developing pressure spring (compression spring)
100 (100a) Image forming apparatus (apparatus body)

Claims (7)

A process cartridge that can be attached to and detached from the main body of the image forming apparatus,
An image carrier on which a latent image is formed;
An image carrier frame for supporting the image carrier;
A developer carrying member carrying the developer;
A developer carrier frame for supporting the developer carrier;
Biasing means for applying a biasing force for biasing the developer carrier to the image carrier to the image carrier frame and the developer carrier frame;
A moving member that is movably provided on either the image carrier frame or the developer carrier frame, and that contacts the biasing means;
With
The moving member has a first position where the urging force by the urging means has a predetermined magnitude, and a second position that reduces the urging force by the urging means to be less than the predetermined magnitude or eliminates the urging force. And an engaging portion that engages with the image carrier frame or the developer carrier frame to hold the position of the moving member at the first position. To process cartridge.   2. The biasing means according to claim 1, wherein the urging means is a pressing spring, and is shorter when the moving member is in the first position than when the moving member is in the second position. Process cartridge.   The said biasing means is a tension spring, and when the said moving member exists in the said 1st position, it becomes longer than when the said moving member exists in the said 2nd position. Process cartridge.   2. The developer carrying member is capable of taking an action position when developing a latent image formed on the image carrier and a separated position farther from the image carrier than the action position. 4. The process cartridge according to any one of items 1 to 3. In an image forming apparatus for forming an image on a recording medium,
A process cartridge according to any one of claims 1 to 4,
An apparatus main body capable of detachably attaching the process cartridge;
An image forming apparatus comprising:   The image forming apparatus according to claim 5, further comprising an action unit that contacts the moving member and moves the moving member from the second position to the first position. The image forming apparatus according to claim 6, wherein the action unit moves the moving member from the second position to the first position in a process of mounting the process cartridge on the apparatus main body.

Images