JP2006301387A - Gear, developing device, developing cartridge, process cartridge, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a configuration forf a drive transmission means by which an image defect can be prevented by absorbing the tolerance of respective parts without enlarging the length in the thrust direction of a developing device, so as to always make the position in the thrust direction of a developing roller constant. <P>SOLUTION: As the typical configurations of the developing device, the developing cartridge, the process cartridge and the image forming apparatus concerning this invention, the gear for transmitting a driving force to the developing roller has a slide member which is provided between a fitting part into the shaft of the developing roller and a gear part, movable in the rotational axial direction of the developing roller and rotated integrally with the gear, and a coil spring provided between the gear and the slide member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gear, a developing device, a developing cartridge, a process cartridge, and an image forming apparatus used in a copying machine, a printer, and the like that employ an electrophotographic system.

  2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic image forming process, a process cartridge system has been adopted in which an image carrier and process means acting on the image forming body are integrally formed into a cartridge that can be attached to and detached from the image forming apparatus main body. ing. According to this process cartridge system, maintenance of the apparatus can be performed by the user himself / herself without depending on the service person, and the operability can be remarkably improved. Therefore, this process cartridge system has been widely adopted in image forming apparatuses.

  Further, as shown in FIG. 9, an inline type image forming apparatus 200 in which a plurality of process cartridges 207 are arranged in a line is provided. As a developing means of the process cartridge 207 used in such an inline type image forming apparatus, development is generally performed in a state where a developing roller 240 as a developer carrier is in contact with a photosensitive drum 201 as an image carrier. Two configurations are known: a contact development method for performing development and a non-contact development method for performing development with the development roller 240 provided with a predetermined gap with respect to the photosensitive drum 201.

  As an example of a developing device for a process cartridge used in such an inline type image forming apparatus, a developing device as shown in FIG. 10 has been proposed and put into practical use.

  In the conventional developing device 207 shown in FIG. 11, a developing roller 245 as a developer carrying member, a developing blade 244 as a developer regulating member, and a developer coating are provided in a developing container 245 containing non-magnetic one-component toner. A coating roller 243 as a member is provided. The toner supplied to the developing roller 240 is sent to a contact portion with the developing blade 244 as the developing roller 240 rotates. Here, the toner on the developing roller 240 becomes a uniform thin layer (toner coat) by the developing blade 244.

  FIG. 11 is a longitudinal sectional view of the process cartridge. Here, a cross section with the center of the developing roller 240 as an axis is shown (a cross-sectional view taken along line AA in FIG. 10).

  As shown in FIG. 11, the developing roller 240 is rotatably attached to bearing portions 247a and 248a of holding members 247 and 248 attached to both ends of the developing container. Here, at one end portion of the developing roller 240, a regulating portion 240c for regulating the amount of movement of the developing roller 240 in the longitudinal direction is provided. A helical gear 279 as a drive transmission member for driving the developing roller is attached to the opposite end face. The helical direction of the helical gear 279 is such that the developing roller 240 is moved in the direction of arrow D in the figure by the thrust force generated when the developing roller 240 is driven.

  Therefore, the developing roller 240 is always at a fixed position by the thrust force of the helical gear 279 and the restricting portion 240c in a state where the developing roller 240 is driven, and a stable image can be obtained.

JP 2004-012523 A (FIG. 1)

  However, in the conventional configuration, it is necessary to provide a gap G in the thrust direction of the developing roller 240 in order to absorb expansion and contraction of the developing container and the like due to environmental fluctuations and tolerances of individual components. The developing roller 240 is a rubber roller obtained by molding a rubber 240b on a metal cored bar 240a, and is heavier than peripheral components. Therefore, when the developing roller 240 is not driven, the developing roller 240 is movable in the thrust direction (H direction in the drawing) with respect to the developing container 245 and the developing blade 244.

  When the process cartridge is transported, vibrations are applied in various directions. When vibration is applied in the longitudinal direction of the developing roller, the developing roller 240 may vibrate in the thrust direction in the process cartridge 207. At this time, rubbing occurs between the developing roller 240 and the developing blade 244 (B portion in FIG. 10) or between the developing roller and the surface of the photosensitive drum (C portion in FIG. 10). The history remains, which may cause an initial image defect.

  As a countermeasure against this, there is a method in which an urging means is provided to always regulate the position of the developing roller (for example, see Patent Document 1).

  The present invention is an extension of this, and the object of the present invention is to absorb the tolerance of each component without increasing the length of the developing device in the thrust direction, and to keep the position of the developing roller in the thrust direction constant. Thus, an object of the present invention is to provide a configuration of a drive transmission means capable of preventing image defects.

  In order to solve the above-described problems, a typical configuration of the developing device, the developing cartridge, the process cartridge, and the image forming apparatus according to the present invention is a gear that transmits a driving force to the developing roller and is fitted to the shaft of the developing roller. A sliding member provided between the gear and the gear portion, movable in the direction of the rotation axis of the developing roller and rotating integrally with the gear, and a coil spring provided between the gear and the sliding member. It is characterized by.

  In the present invention, the gear is a helical gear, and when the helical gear is driven, the direction of the force generated in the rotation axis direction of the developing roller and the pressure applied by the coil spring are the same direction. And

  In the present invention, the sliding member is provided with a snap-fit claw shape, and the gear is provided with a hole shape corresponding to the claw shape.

  Furthermore, in the present invention, one end of the coil spring is positioned within a gear tooth width.

  According to the present invention, since the developing roller is biased in the thrust direction by the coil spring provided in the gear for transmitting the driving force to the developing roller, the developing roller is urged in the thrust direction. The position of the developing roller in the thrust direction is constant. In addition, by having a sliding member that rotates integrally with the gear, the developing roller can rotate smoothly by the sliding member when the developing roller is rotating.

  Further, since the coil spring is disposed within the gear tooth width, the above-described operation can be performed without increasing the size in the thrust direction of the developing device, the developing cartridge, the process cartridge, and the image forming apparatus.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

Embodiments of a developing device, a developing cartridge, a process cartridge, and an image forming apparatus according to the present invention will be described with reference to the drawings.
(Overall configuration of image forming apparatus)
First, the overall configuration of the image forming apparatus will be outlined with reference to FIG.

  The image forming apparatus 100 shown in FIG. 2 includes four photosensitive drums 1a to 1d that are image carriers arranged side by side in the vertical direction. The photosensitive drum 1 is driven to rotate counterclockwise in the drawing by a driving means (not shown).

  Around the photosensitive drum 1, in order according to the rotation direction, charging devices 2a to 2d for uniformly charging the surface of the photosensitive drum 1, laser beams are irradiated based on image information, and electrostatic latent images on the photosensitive drum 1 are irradiated. Scanner units 3a to 3d for forming images, developing units 4a to 4d for developing toner as a developer image by attaching toner as a developer to the electrostatic latent image, and transferring the toner image on the photosensitive drum 1 to the transfer material S An electrostatic transfer device 5, cleaning devices 60a to 60d for removing transfer residual toner remaining on the surface of the photosensitive drum 1 after transfer, and the like are disposed. Here, the photosensitive drum 1, the charging device 2, the developing unit 4, and the cleaning device 60 are integrated into a cartridge to form a process cartridge 7.

  As shown in FIG. 2, 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.

  As shown in FIGS. 2 and 3, as an image forming operation, the process cartridges 7a to 7d are sequentially driven in accordance with the image forming timing, and the photosensitive drums 1a to 1d are rotated counterclockwise in accordance with the drive. Is driven to rotate. Then, the scanner units 3 corresponding to the respective process cartridges 7 are sequentially driven. By this driving, the charging device 2 applies a uniform charge to the circumferential surface of the photosensitive drum 1, and the scanner unit 3 exposes the circumferential surface of the photosensitive drum 1 in accordance with an image signal to perform the photosensitive drum 1. An electrostatic latent image is formed on the peripheral surface. The developing roller 40 in the developing unit 4 forms (develops) a toner image on the circumferential surface of the photosensitive drum 1 by transferring the toner to the low potential portion of the electrostatic latent image.

  At the timing when the leading edge of the toner image on the peripheral surface of the most upstream photosensitive drum 1a is rotated and conveyed to the point facing the electrostatic transfer belt 11, the image formation start position of the transfer material S coincides with the point facing the opposite end. As described above, the registration roller pair 19 starts rotating to feed the transfer material S to the electrostatic transfer belt 11.

To the transferred transfer material S, the toner images on the photosensitive drums 1 are sequentially transferred by an electric field formed between the photosensitive drums 1 and the transfer rollers 12. The transfer material S onto which the four color toner images have been transferred is separated from the electrostatic transfer belt 11 by the curvature of the driving roller 13 and is carried into the fixing unit 20. After the toner image is thermally fixed by the fixing unit 20, the transfer material S is discharged out of the main body by the discharge roller pair 23 with the image surface facing down from the discharge unit 24.
(Process cartridge)
Next, the process cartridge embodying the present invention will be described in detail with reference to FIGS.

  FIG. 3 is a main cross-sectional view of the process cartridge 7 containing toner, and FIG. 4 is a perspective view of the process cartridge 7. The yellow, magenta, cyan, and black process cartridges 7a to 7d have the same configuration.

  The process cartridge 7 includes a drum-shaped image carrier that is an image carrier, that is, a photosensitive drum 1, an image carrier unit 50 including a charging unit 2 and a cleaning unit 60, and an electrostatic latent image on the photosensitive drum 1. The developing unit 4 has developing means for developing the toner.

  In the image carrier unit 50, the photosensitive drum 1 is rotatably attached to a cleaning frame 51 via a bearing. A charging device 2 for uniformly charging the surface of the photosensitive drum 1 and a cleaning device for removing the developer (toner) remaining on the photosensitive drum 1 are provided on the periphery of the photosensitive drum 1. A cleaning blade 60 is disposed.

  Residual toner removed from the surface of the photosensitive drum 1 by the cleaning blade 60 is sequentially sent to a waste toner chamber 53 provided behind the cleaning frame by a toner feeding mechanism 52. Then, the driving force of a driving motor (not shown) is transmitted to one end at the rear of the drawing, so that the photosensitive drum 1 is driven to rotate counterclockwise in the drawing according to the image forming operation.

  The developing unit 4 includes a developing roller 40 that contacts the photosensitive drum 1 and rotates in the direction of arrow E, a toner container 41 that contains toner, and a developing frame body 45. As shown in FIG. 4, the developing roller 40 is rotatably supported by the developing frame body 45 via holding members 47 and 48. Further, as shown in FIG. A toner supply roller 43 and a developing blade 44 that rotate in the direction of arrow F in contact with the developing roller 40 are disposed. Further, the toner container 41 is provided with a toner transport mechanism 42 for stirring the toner contained therein and transporting the toner to the toner supply roller 43.

  The developing unit 4 is entirely composed of an image carrier unit by pins 49a around a support shaft 49 that is a rocking center provided on each of holding members 47 and 48 attached to both ends of the developing unit 4. In the state in which the process cartridge 7 is alone (not mounted on the printer body), the developing roller 40 is driven by the rotational moment about the support shaft 49 and the photosensitive drum 1 is rotated. The developing unit 4 is always urged by a pressurizing spring (not shown) which is an urging member so as to come into contact with.

  During development, when the toner stored by the toner transport mechanism 42 is transported to the toner supply roller 43, the toner supply roller 43 that rotates in the direction of arrow F slides with the developing roller 40 that rotates the toner in the direction of arrow E. The toner is supplied to the developing roller 40 by rubbing and is carried on the developing roller 40. The toner carried on the developing roller 40 reaches the developing blade 44 as the developing roller 40 rotates, and the developing blade 44 regulates the toner to form a predetermined toner thin layer.

  Further, the toner thin layer on the developing roller 40 is conveyed to a developing unit where the photosensitive drum 1 and the developing roller 40 are in contact with each other, and in the developing unit, a photosensitive member is applied by a DC developing bias applied to the developing roller 40 from a power source (not shown). The latent image is developed by attaching to the electrostatic latent image formed on the surface of the drum 1. The toner remaining on the surface of the developing roller 40 without contributing to the development is returned to the inside of the developing frame as the developing roller 40 rotates, and is peeled off and collected from the developing roller 40 at the rubbing portion with the toner supply roller 43. . The collected toner is stirred and mixed with the remaining toner by the toner transport mechanism 42.

  Here, the surface of the toner supply roller is set so that the surface of the developing roller enters the developing roller. In the nip area (the area where the toner supplying roller is crushed), the toner is supplied and the development residual toner on the surface of the developing roller is peeled off. It is carried out.

In the contact development method in which development is performed by contacting the photosensitive drum 1 and the developing roller 40 as in the present invention, the photosensitive drum 1 is preferably a rigid body, and the developing roller 40 is preferably 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.
(Developer)
Next, the construction of the developing roller of the developing device and the gear for transmitting the driving force to the developing roller and the mounting method will be described with reference to FIGS. 1 and 5 to 8.

  As shown in FIG. 1, the developing roller 40 is a conductive roller formed of a metal cored bar 40a and a conductive material 40b. The cored bar support portion 40 d of the developing roller 40 is rotatably supported by the holding member 47. Note that the end of the opposite side of the developing roller 40 is also rotatably supported by the holding member 48 at the core metal support.

  The developing roller 40 and the holding members 47 and 48 are attached to the developing container 45 by the following procedure.

  As shown in FIG. 5, a hole 45 h for positioning with the holding member 47 and a pilot hole 45 i for screwing the holding member are provided on the side surface in the longitudinal direction of the developing container 45. On the other hand, as shown in FIG. 6, the holding member 47 is provided with a positioning boss 47 e and a hole 47 f for passing a screw at a position corresponding to the hole 45 h provided on the side surface of the developing container 45.

  Note that the opposite side of the developing container 45 in the longitudinal direction (side surface to which the holding member 48 is attached) has the same configuration.

  As shown in FIG. 6, the developing roller 40 is placed on the developing container 45 in a state where the developing blade 44 is attached, and holding members 47 and 48 (not shown) are placed along the positioning holes 45h from both side surfaces of the developing container 45. In addition, the developing roller 40 and the toner supply roller 43 are combined so as to match the bearing portions 47a and 47b of the holding members 47 and 48, and the holding members 47 and 48 are fixed to the developing container 45 with screws 85.

  Incidentally, when assembling the process cartridge, the toner supply roller 43 is impregnated with a small amount of toner, and after the development roller 40 and the toner supply roller 43 are assembled to the development container 45, the development roller 40 is rotated several times to acclimatize. Is going. The toner supply roller 43 is made of a material such as foamed urethane in the core metal, and has a very large friction coefficient with the developing roller 40 when no toner is present. When the new process cartridge 7 is used, if the toner supply roller 43 and the development roller 40 rub against each other during the time until the toner is supplied from the toner container 41 to the development roller 40 and the toner supply roller 43, the toner supply roller 43 There is a possibility of damaging it.

Therefore, the toner supply roller 43 is impregnated with toner in advance to reduce friction between the toner supply roller 43 and the developing roller 40. Therefore, a small amount of toner is present on the developing blade 44 and the developing roller 40 after the developing roller 40 and the toner supply roller 43 are assembled and run-in.
(Details of biasing means)
As shown in FIG. 8, a regulating portion 40 c for regulating the thrust direction of the developing roller 40 (the direction indicated by the arrow H in the drawing) is provided at the end of the developing roller 40. On the other hand, the holding member 48 is also provided with a restricting portion 48g at a portion corresponding to the restricting portion of the developing roller 40. In the present embodiment, the thrust direction is regulated by providing the developing roller core metal 40a with a portion having a different outer diameter, and the level difference caused by the difference in diameter and the wall surface provided on the developing roller bearing portion 48a of the holding member 48 on the developing roller. This is used as a thrust restricting portion 48g.

  A contact plate 76 which is a power supply means to the developing roller 40 is fixed to the holding member 48 by means such as snap fit or heat caulking.

  Here, the contact plate 76 is a part of a power supply path for applying a bias from the main body of the image forming apparatus, and power can be supplied when the developing device is incorporated in the image forming apparatus (not shown). ).

  The method for assembling the holding member 48 is the same as the above-described assembling on the developing unit non-drive side.

  As shown in FIG. 7, the holding member 47 is provided with a developing roller bearing portion 47a. In the present embodiment, the bearing portion 47a is a through-hole having the same diameter as that of the core bar 40a of the developing roller, and there is a gap G in the thrust direction between the developing roller 40 and the holding member 47 on the driving side. is doing.

  Next, a configuration of a gear that transmits driving to the developing roller 40 will be described.

  As shown in FIGS. 1 and 7, a helical gear 79 as a drive transmission means to the developing roller 40 is attached to the developing roller end portion 40f by fitting. Further, the helical gear 79 and the developing roller end portion 40f are provided with a shape 40g such as D-cut or two-sided removal to prevent the helical gear 79 from slipping. Here, the twisting direction of the helical gear 79 is such that the thrust force generated when driving is applied in the non-driving side direction (the direction of arrow D in the figure), and the developing roller 40 is driven to rotate. During the image formation, that is, when the image is formed, the developing roller 40 rotates while being positioned on the non-driving side by the non-driving side restricting portion 40c described above.

  FIG. 8 is a sectional view of the helical gear 79.

  The helical gear 79 has a fitting portion 79a with the developing roller and a positioning portion 79b in the thrust direction with the developing roller. In the present embodiment, the positioning in the thrust direction is performed using the end face of the D-cut shape 40g provided on the cored bar portion of the developing roller 40.

  The helical gear 79 is provided with a coil spring 80 for urging the developing roller 40 and an accommodating portion 79c that rotates integrally with the helical gear 79 and accommodates a sliding member 81 that covers the coil spring 80. ing. Further, a hole 79d is provided in the accommodating portion 79c. On the other hand, the sliding member 81 is provided with a snap-fit claw shape 81a at a position corresponding to the hole 79d of the helical gear.

  The coil spring 80 as an urging means is assembled by incorporating the coil spring 80 into the accommodating portion 79c of the helical gear 79, and the sliding member 81 so as to cover the coil spring 80 from above the helical gear 79 in the snap fit 81a. It is done by fixing. Here, the sliding member 81 is movable in the thrust direction while being urged by the coil spring 80. Further, the amount by which the sliding member 80 can move is set to be larger than a gap (an amount corresponding to G in FIG. 7) that can be generated when the developing roller 40 is incorporated into the developing device 4. The sliding member 80 has a sliding portion 81b with a side cover 77 described later.

  In the present embodiment, the pressing force of the coil spring 80 is determined in consideration of the weight of the developing roller 40, the packaging state during transport of the developing device, and the contact pressure.

  In the present embodiment, the helical gear 79 and the sliding member 81 are made of a material such as polyacetal resin.

  In this embodiment, the snap fit shape 81a is provided on the sliding member 81 so that the helical gear 79, the coil spring 80, and the sliding member 81 can be handled in advance as one unit, and the helical gear hole 79d is provided. As long as the helical gear 79 and the sliding member 81 can be rotated integrally after the helical gear 79 is assembled to the developing roller 40, the shape is the same as that of the present embodiment. It is not limited to.

  A side cover 77 is provided outside the helical gear 79 in the longitudinal direction (see FIG. 7). The side cover 77 is attached by a snap fit provided on the holding member 47 while determining the position with the holding member 47 by the side cover positioning boss of the holding member 47 (not shown).

  After the helical gear 79 with the coil spring 80 and the sliding member 81 attached is fitted to the developing roller 40 and assembled, the side cover 77 is assembled to the holding member 47. The side cover 77 is provided with a sliding surface at a portion facing the sliding portion 81 b of the sliding member 81.

  When the side cover 77 is assembled to the holding member 47, the sliding member 81 is pushed in the direction D in the figure by the sliding surface 81b. Here, since the thrust direction of the helical gear 79 is regulated with respect to the developing roller 40, the coil spring 80 is compressed and a predetermined pressure is generated.

  The incorporation of the developing roller 40 into the developing device 4 is completed by the above procedure. At this time, the developing roller 40 is moved in the thrust direction by the coil spring 80, and is positioned by the positioning portion 48g on the non-driving side, and at the same time is held by the positioning portion 48g with a constant pressure.

  When the assembled process cartridge 7 is transported to the user, and the developing device 4 is vibrated in the thrust direction, the developing roller 40 and the developing member 45 and the bearing member 47 have a gap G in the thrust direction. Try to make a round trip.

  In the present embodiment, since the developing roller 40 is always positioned by the pressure of the coil spring 80, the developing roller 40 does not move in the thrust direction of the developing container 45. For this reason, the developing blade 44 and the developing roller 40 fixed to the developing roller 40 and the developing container 45 are not rubbed, and the surface of the developing roller 40 is rubbed at the contact position between the developing roller 40 and the developing blade 44. The phenomenon of local wear and toner sticking does not occur, and image defects can be prevented. Similarly, even when transport or the like is performed with the photosensitive drum 1 and the developing roller 40 in contact with each other, it is possible to prevent image defects caused by the rubbing between the photosensitive drum 1 and the developing roller 40. is there.

  Further, in the present embodiment, the diameter of each component is arranged in descending order: the diameter obtained by adding the thickness to the root circle diameter of the helical gear 79; the outer diameter of the sliding member 81; the outer diameter of the coil spring 80; The inner diameter is set to 80, and the developing roller fitting portion diameter of the helical gear 79 is set. By doing so, the sliding member 81 and the coil spring 80 can be disposed within the tooth width of the helical gear 79 without suppressing the movement of the sliding member 81 and the coil spring 80. In spite of the provision of 80, the developing device 4 can be configured without increasing the longitudinal dimension.

  Further, since the helical gear 79 and the sliding member 81 are arranged substantially coaxially with the developing roller 40, the developing roller 40 can rotate with a constant load when the developing roller 40 rotates. Rotation unevenness is not caused.

  In each of the above-described embodiments, the process cartridge having the developing device to which the present invention is applied and the image forming apparatus that can be attached and detached are described. However, the present invention is not limited to this and is installed in the image forming apparatus. The same effect can be obtained by applying the present invention to a developing cartridge in which only the developing device or the developing device is detachable.

It is a disassembled perspective view of the gear, spring, and sliding member which concern on embodiment of this invention. 1 is an overall configuration diagram of an image forming apparatus. It is a cross-sectional explanatory view of a process cartridge. It is a disassembled perspective view of a process cartridge. It is a figure explaining the assembly method of a process cartridge. It is a figure explaining the structure of a holding member. It is a fragmentary sectional view explaining the composition of a process cartridge. It is sectional drawing which shows the structure of a gear, a spring, and a sliding member. It is the whole schematic diagram explaining the conventional image forming apparatus. It is sectional drawing explaining the conventional process cartridge. It is a fragmentary sectional view explaining the conventional developing device.

Explanation of symbols

S transfer material 1 photosensitive drum 2 charging device 3 scanner unit 4 developing unit 5 electrostatic transfer device 6 cleaning device 7 process cartridge 11 electrostatic transfer belt 12 transfer roller 19 registration roller pair 20 fixing unit 21 fixing roller pair 21a heating roller 21b Pressure roller 23 Discharge roller pair 24 Discharge unit 40 Development roller 41 Toner storage unit 42 Toner transport mechanism 43 Toner supply roller 44 Development blade 45 Development container 47, 48 Holding member 47a, 48a Development roller bearing unit 47b, 48b Toner supply roller bearing Part 48e positioning boss 48g developing roller thrust direction restricting part 49 support shaft 49a pin 50 image carrier unit 51 cleaning frame 52 toner feeding mechanism 53 waste toner chamber 60 cleaning blade 76 contact plate 77 Id cover 79 helical gear 80 pressure spring 81 sliding member 100 image forming apparatus

Claims (11)

In a gear for transmitting a driving force to a developing roller that is provided to develop a latent image on a photosensitive drum and rotates while carrying a developer,
A sliding member provided between a fitting portion with the shaft of the developing roller and the gear portion, movable in the direction of the rotating shaft of the developing roller and rotating integrally with the gear, and between the gear and the sliding member A gear characterized by having a coil spring provided on the gear.   2. The gear according to claim 1, wherein the gear is a helical gear, and the direction of the force generated in the rotation direction of the developing roller when the helical gear is driven is the same as the pressure applied by the coil spring. Gear.   The gear according to claim 1, wherein the sliding member is provided with a snap-fit claw shape, and the gear is provided with a hole shape corresponding to the claw shape.   The gear according to claim 1, wherein one end of the coil spring is located within a gear width of the gear.   A developing device comprising the gear according to claim 4.   6. A cover portion covering the periphery of the gear, wherein the slide portion provided at one end of the sliding member in the developing roller rotation axis direction and the cover portion are slidably in contact with each other. The developing device described.   7. A developing cartridge comprising the developing device according to claim 5 and configured to be detachable from the image forming apparatus.   A process cartridge comprising an image carrier and the developing device according to claim 5, wherein the process cartridge is detachable from the image forming apparatus.   An image forming apparatus comprising an image carrier and the developing device according to claim 5.   8. An image forming apparatus comprising an image carrier, wherein the developing cartridge according to claim 7 is detachable.   9. An image forming apparatus, wherein the process cartridge according to claim 8 is detachable.

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