JP2006234903A - Process cartridge and electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process cartridge and an electrophotographic image forming apparatus in which a displacement detection pattern is actually formed on a sheet conveyance means to minimize color shift among four colors, the pattern is read by a detection means, more stable phase matching of a photoreceptor drum is realized without operating a phase detection sequence for detecting an amount of displacement, speed variation of the photoreceptor drum is suppressed and shift of an image is reduced in a color electrophotographic image forming apparatus. <P>SOLUTION: A rotation phase of the photoreceptor drum 1 is defined by a first drive point by making difference of an amount of rotation drive between the first drive point and a second drive point for driving a drum flange member 60 and making rotation drive force of a drive point for driving a coupling member 70 approximately equivalent. Then, the above problem is soled by constituting so that that rotation phases from a drum phase gear 98 to the photoreceptor drum 1 are uniquely determined and phases of photosensitive drums in each color are aligned. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus having a function of forming an image on a recording medium such as a sheet, such as a copying machine, a printer, or a facsimile machine, and more particularly to forming a multicolor image on a recording medium. This relates to prevention of misalignment of the printing position at the time.

  In recent years, the demand for color electrophotographic image forming apparatuses capable of forming color images has increased. (1) Low running cost (2) Small space (3) Low power (4) High image quality (5) High It is expected to introduce a color image forming apparatus capable of achieving six items of speed (6) improvement in operability.

  Among them, (6) while simplifying operability, (5) high speed and (4) a technique for providing a high-quality color image, a color image forming apparatus is provided with yellow, There is a system that uses four process cartridges of magenta, cyan, and black to form four photosensitive drums in parallel to form an image, thereby improving operability and increasing the speed. This system is called a tandem or 4-drum system color image forming apparatus.

  As a problem in this method, since four color images are independently formed to form a single color image, when the image formation point formed by each drum is displaced from the target (ideal) position, There is a problem that a relative positional shift between colors appears as a color shift between colors (for example, a color shift between black and cyan).

For example, the positional accuracy of the four photosensitive drums and the four exposure units corresponding to the four photosensitive drums causes a positional deviation in the scanning direction for each color, and appears as a color deviation on the image when four colors are superimposed. There's a problem. For this, an improvement method such as positioning all of the four photosensitive drums and the four exposure means with the both side plates of the image forming apparatus main body, and minimizing the mutual positional error generated between the units. There is. (For example, see Patent Document 1)
Further, if a certain amount of positional deviation from the ideal position occurs periodically due to the rotational fluctuation of the photoconductive drum, the color misregistration that is approximately twice the maximum monochromatic positional misregistration is caused by the rotational phase shift of the photosensitive drum of each color. May occur. In order to prevent this, a misregistration detection pattern is formed on the sheet conveying means, the pattern is read by the detecting means, the misregistration amount is calculated, and the rotational phases of a plurality of drive gears for driving the photosensitive drum are photo-detected. There is an improvement method in which the rotational phase of the drive gear is controlled in advance so as to be in an ideal position during image formation based on the detection signal and the position deviation calculation value. (For example, see Patent Document 2)
JP 2001-242671 A JP 2003-177588 A

  However, in the above-described conventional configuration, it is possible to suppress the mutual positional error between the photosensitive drums and the exposure means between the four colors, but it is impossible to match the rotational phases of the photosensitive drums that actually form images. Further, in order to adjust the rotation phase and minimize the color misregistration, it is necessary to actually form a misregistration detection pattern on the sheet conveying unit, read the pattern by the detecting unit, and detect the misregistration amount. When the method of correcting the deviation between the rotational phase of the photosensitive drum that actually forms the image and the rotational phase of the photosensitive drum drive gear on the apparatus main body side is used, the detection pattern is formed and the phase correction is performed based on the detection result. Since a long time is required, there is a possibility that the user may wait for a long time to print.

  The present invention has been made in view of the circumstances as described above, and realizes more stable phase alignment of the photosensitive drum without operating a conventional phase detection sequence that requires time for detection, and also provides a photosensitive drum. It is an object of the present invention to provide a technique capable of reducing the image shift by suppressing the speed fluctuation.

  The first embodiment of the present invention includes a photosensitive drum, a rotating shaft passing through the center of the photosensitive drum, a drum flange member for transmitting the driving of the rotating shaft to the photosensitive drum, and the rotating shaft. And a coupling member that is driven by the electrophotographic image forming apparatus main body, and is attachable to and detachable from the electrophotographic image forming apparatus main body. The drum flange member transmits a rotational driving force that is transmitted to the member and that is opposed to the first driving point and that determines the rotational phase of the photosensitive drum, and is smaller than the rotational driving of the first driving point. A second drive point that transmits to the shaft, and the phase of the drive point of the rotary shaft and the drum flange member is matched with the phase of the coupling portion of the rotary shaft and the coupling. A process cartridge.

  According to a fourth embodiment of the present invention, there is provided a photosensitive drum, a rotating shaft passing through a center of the photosensitive drum, a drum flange member for transmitting driving of the rotating shaft to the photosensitive drum, and the rotating shaft. A process cartridge detachably attached to the electrophotographic image forming apparatus main body and having a coupling member that is driven by the electrophotographic image forming apparatus main body. A first driving point that determines the rotational phase of the photosensitive drum, and a second driving point that transmits a rotational driving force smaller than the rotational driving of the first driving point to the drum flange member. Engaging the coupling member coupled by matching the phase of the driving point of the rotating shaft and the drum flange member and the phase of the coupling portion of the rotating shaft and the coupling. Has a body coupling member, said main assembly coupling member and the coupling member is a color electrophotographic image forming apparatus characterized by coupling in only one rotational one phase is configured to be engaged.

  According to the present invention, it is possible to achieve more stable phase alignment of the photosensitive drum without activating the conventional phase detection sequence that requires time for detection, and to suppress fluctuations in the speed of the photosensitive drum, thereby shifting the image shift. It is possible to provide a technique capable of reducing the above.

  Hereinafter, an electrophotographic image forming apparatus and a process cartridge according to the present invention will be described in more detail with reference to the drawings.

(Image forming device main unit)
In FIG. 1, Y, M, C, and Bk are four first to fourth image forming images that form an image with developers of yellow, magenta, cyan, and black corresponding to the color separation component colors of the full-color image, respectively. It is a station. The Y, M, C, and Bk are arranged in parallel in the apparatus main body 100 in order from the bottom to the top.

  In each image forming station Y, M, C, Bk, charging means 2 (2a) for uniformly charging the surface of the photosensitive drum 1 around the electrophotographic photosensitive drum 1 (1a, 1b, 1c, 1d), respectively. , 2b, 2c, 2d), developing means 40 (40a, 40b, 40c, 40d) for developing the latent image formed on the photosensitive drum 1 with a developer to visualize it, and developing formed on the photosensitive drum 1 Electrophotographic process means such as cleaning means 6 (6a, 6b, 6c, 6d) for removing the developer remaining on the photosensitive drum 1 after transferring the agent image to the recording medium is disposed. As will be described later, the photosensitive drum 1, the charging unit 2, the developing unit 4, and the cleaning unit 6 are integrally provided in a process cartridge 7.

  Further, the photosensitive drum 1 is selectively exposed on the back side of the image forming apparatus main body based on image information. A scanner unit 3 (3a, 3b, 3c, 3d) for forming a latent image on the photosensitive drum 1 is provided.

  A cassette 17 containing a recording medium S is attached to the lower part of the apparatus main body. A recording medium conveying means is provided so that the recording medium S is conveyed to the upper side of the apparatus main body through the position of each photosensitive drum 1. That is, a feeding roller 18 and a registration roller pair 19 for separating and feeding the recording medium S in the cassette 17 one by one are provided. Above the cassette 17, electrostatic transfer means 5 for transferring the toner images formed on the respective photosensitive drums 1 (1 a to 1 d) onto the recording medium (transfer material) S is provided. The transfer belt 11 is stretched between the four rollers of the driving roller 13, the two driven rollers 14 a and 14 b, and the tension roller 15. The transfer belt 11 circulates so as to face and be in contact with all the photosensitive drums 1. Then, by applying a voltage to the transfer belt 11 and the electrostatic adsorption roller 22, the conveyed recording medium S is conveyed upward in the state of being electrostatically adsorbed to the transfer belt 11.

  At the time of image formation, each photosensitive drum 1 is rotated. Then, the photosensitive drum 1 uniformly charged by the charging unit 2 is selectively exposed from the scanner unit 3. Thereby, an electrostatic latent image is formed on the photosensitive drum 1. The latent image is developed by the developing means 40. Thus, each color developer image is formed on each photoconductive drum 1. In synchronization with this image formation, the recording medium S is conveyed to a position facing the photosensitive drum 1 by the recording medium conveying means. Then, by applying a transfer bias to the transfer roller 12 (12a, 12b, 12c, 12d) facing each photoconductor drum 1 with the transfer belt 11 in between, each color developer image on each photoconductor drum 1 is recorded. The image is superimposed and transferred to the medium S. As a result, a color image is formed on the recording medium S. The transfer roller 12 faces each photosensitive drum 1 with the transfer belt 11 in between.

  The recording medium S on which the color image is formed as described above is heated and pressed by the fixing unit 20 to fix the developer image. Thereafter, the recording medium S is discharged to the discharge unit 24 by the discharge roller 23. The fixing unit 20 is disposed at the upper part of the apparatus main body.

  After the developer image is transferred to the recording medium S in each of the first to fourth image forming stations Y, M, C, and Bk, the photosensitive drum 1 is subjected to residual deposits such as a transfer residual developer by the cleaning unit 6. Removed. The photosensitive drum 1 is repeatedly used for image formation.

(Process cartridge)
In each of the first to fourth image forming stations Y, M, C, and Bk, the photosensitive drum 1, the charging unit 2, the developing unit 4, and the cleaning unit 6 are each a process cartridge 7 (7a, 7a, 7) as a unit. 7b, 7c, 7d). Here, the process cartridge 7 can be integrally attached to and detached from the apparatus main body 100.

  Next, the configuration of the process cartridge (hereinafter referred to as “cartridge”) 7 will be described.

  As shown in FIG. 1, the cartridge 7 of the present embodiment includes a photosensitive drum 1, a charging unit 2, and a cleaning blade 6 as a cleaning unit. 50c, 50d) and a developing unit 4 (4a, 4b, 4c, 4d) as a second frame having a developing means. The developing unit 4 is rotatably coupled to the cleaning unit 50.

  The attachment / detachment operation of each cartridge 7 with respect to the apparatus main body 100 is performed in a state where the opening / closing door 26 is opened and the cartridge insertion port 91 (see FIG. 8) in the apparatus main body 100 is largely opened. The open / close door 26 can be opened and closed with respect to the apparatus main body 100. The opening / closing door 26 is provided in front of the apparatus main body 100.

  That is, the door 26 is centered on a hinge shaft 27 (see FIG. 8) provided at the lower part of the electrostatic transfer means 5, as shown by a two-dot chain line in FIG. 1 or a solid line in FIG. Push it down and open it. As a result, the insertion port 91 (see FIG. 8) can be opened. Conversely, by closing the door 26, the door 26 can be closed with respect to the apparatus main body 100 (solid line state in FIG. 1). Here, the door 26 is a front cover portion of the apparatus main body 100, and the electrostatic transfer means 5 is provided inside thereof.

  The configuration for attaching and detaching the cartridge 7 to and from the apparatus main body 100 will be described in detail later.

  In the following description, the short direction of the cartridge or a member constituting the cartridge refers to a direction in which the cartridge is attached to or detached from the apparatus main body, and the longitudinal direction refers to a direction that intersects the direction in which the cartridge is attached to or detached from the apparatus main body. Regarding the cartridge, the back means the surface opposite to the cartridge when viewed from the front of the main body, and the left and right indicate the left or right when the cartridge is viewed from the front of the main body. Further, the upper surface of the cartridge is a surface located above in a state where the cartridge is mounted on the apparatus main body, and the lower surface is a surface located below.

  2 is a sectional view of the cartridge, FIGS. 3 and 4 are perspective model views of the cartridge, FIGS. 5 and 6 are perspective model views of the developing units constituting the cartridge, respectively, and FIG. 7 is an explanation of the separation operation of the developing unit. FIG.

  In each of the image forming stations Y, M, C, and Bk, the cartridge 7 is the developer stored in the developer container of the developing means, and the cartridge 7a attached to the first image forming station Y is a yellow developer. Yes, the cartridge 7b attached to the second imaging station M is a magenta developer, and the cartridge 7c attached to the third imaging station C is a cyan developer. The cartridge 7d attached to the image station Bk is a black developer. The cartridges 7 have the same configuration except that the colors of the developers stored are different.

  In the cartridge 7 of this embodiment, the cleaning unit 50 and the developing unit 4 are coupled.

  The photosensitive drum 1 is rotatably attached to the cleaning unit 50. On the circumference, as described above, the charging means 2 and the cleaning blade 6 are arranged. Further, the residual developer removed from the surface of the photosensitive drum 1 by the cleaning blade 6 is sent to a removed developer chamber 53 provided behind the cleaning frame 51 by the developer feeding mechanism 52. The charging means 2 uses a contact charging type. The charging means 2 is a conductive charging roller formed in a roller shape. This roller is brought into contact with the surface of the photosensitive drum 1. Then, a charging bias voltage is applied to this roller. Thereby, the surface of the photosensitive drum 1 is uniformly charged.

  The developing unit 4 includes a developer container 41 and a developing frame body 45. The developer in the developer container 41 is sent to the developer supply roller 43 by the developer transport mechanism 42. Then, a frictionally charged developer is applied to the outer periphery of the developing roller 40 by the roller 43 and a developing blade 44 pressed against the outer periphery of the developing roller 40 as a developing unit. A developing bias is applied to the developing roller 40 from the apparatus main body. As a result, the electrostatic latent image formed on the electrophotographic photosensitive drum 1 is developed. The developing roller 40 is disposed to face the photosensitive drum 1. The developing roller 40 is in contact with the photosensitive drum 1 and develops the electrostatic latent image formed on the photosensitive drum 1.

  As shown in FIG. 3, the photosensitive drum 1 is rotatably supported on the cleaning frame 51 by bearings 64 and 65 at both ends thereof. In addition, a coupling member 70 that transmits a driving force from a driving motor (not shown) provided in the apparatus main body 100 is provided at one end. As a result, the photosensitive drum 1 is driven to rotate counterclockwise (FIG. 2). In conjunction with the rotation of the photosensitive drum 1, the developer feeding mechanism 52 of the removed developer chamber 53 is driven via a gear train (not shown).

  The bearings 64 and 65 are supported by the grip portions 82 and 83 and the cleaning frame 51. The grip portions 82 and 83 are used when the cartridge 7 is mounted on the apparatus main body 100. The cleaning frame 51 is provided with a shutter member 101 that protects the photosensitive drum 1. The shutter member 101 is opened / closed by the shutter opening / closing member 102 in accordance with the cartridge attaching / detaching operation.

  The bearing 64 supports one end of the photosensitive drum 1 in the axial direction. The bearing 64 protrudes outward from the cleaning frame 51 on the one end side in the axial direction and on the same axis as the axis of the photosensitive drum 1.

  The bearing 65 supports the other end side of the photosensitive drum 1 in the axial direction. The bearing 65 protrudes outward from the cleaning frame 51 on the other end side in the axial direction and on the same axis as the axis of the photosensitive drum 1.

(Unit rotation configuration)
The entire developing unit 4 is rotatably supported with respect to the cleaning unit 50. That is, as shown in FIGS. 5 and 6, in the developing unit 4, holes 47 a and 48 a serving as rotation centers are provided in bearing members 47 and 48 attached to both ends of the unit 4. And the coupling shafts 62 and 63 which fit the cleaning frame 51 are inserted into the holes 47a and 48a. Thus, the developing unit 4 is rotatably attached to the cleaning frame 51.

  Further, when the cartridge 7 is in a single state (a state where it is not attached to the apparatus main body), the developing roller 40 comes into contact with the photosensitive drum 1 by a rotational moment about the coupling shafts 62 and 63. Therefore, as shown in FIGS. 6 and 7, as an elastic member for pressing the developing unit 4, a pressing spring 54 is provided on the side where the bearing member 47 is provided, and a side where the bearing member 48 is provided. In this case, a tension spring 90 as a pressure member is disposed between the cleaning unit 50 and the developing unit 4.

  As shown in FIGS. 5 and 6, force receiving portions 47 b and 48 b are integrally provided on the bearing members 47 and 48. When the developing roller 40 is separated from the photosensitive drum 1, a contact / separation cam 8 (FIG. 7) as a separation unit of the main body of the printer 100 contacts the force receiving portions 47 b and 48 b.

  Here, as shown in FIG. 7, the holes 47a and 48a serving as the rotation centers are located between the developing roller 40 and the force receiving portions 47b and 48b with respect to the mounting direction Q in which the cartridge 7 is mounted on the apparatus main body 100. is there.

  With this arrangement, when the cartridge 7 is mounted on the apparatus main body 100, the force receiving portions 47b and 48b ride on the cam 8 provided on the apparatus main body. Accordingly, in the main body 100, the developing roller 40 and the photosensitive drum 1 can always be kept apart with an easy configuration. When the image is formed, the cam 8 that is a force applying member to the cartridge 7 is rotated to release the push-up by the cam 8. As a result, the developing roller 40 is pressed against the photosensitive drum 1 by the force of the pressing spring 54 and the tension spring 90. Accordingly, the developer is supplied to the photosensitive drum 1.

  When the developing roller 40 is separated from the photosensitive drum 1 again, the cam 8 is rotated in the direction of arrow D in FIG. 7 to push up the force receiving portions 47b and 48b. As a result, the developing roller 40 is separated from the photosensitive drum 1 by a predetermined gap. The force receiving portions 47b and 48b are provided in the developing unit 4.

  In the present embodiment, a contact development method is used in which development is performed with the photosensitive drum 1 and the developing roller 40 in contact with each other. Therefore, 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 the developer is used.

(Drive transmission configuration)
4 and 5, the developing unit 4 is provided with a cartridge driving gear (helical gear) 71 as a developing roller driving force receiving portion that receives a driving force for rotating the developing roller 40 from the apparatus main body 100. . The cartridge drive gear 71 meshes with a main body development drive gear (not shown, helical gear) provided in the apparatus main body 100 in a state where the cartridge 7 is mounted on the apparatus main body 100, and from the main body development drive gear. Receives driving force. The rotation of the cartridge driving gear 71 drives the developing roller 40, the developer transport mechanism 42, and the developer supply roller 43 through a gear train (not shown). The cartridge drive gear 71 is provided on one end side in the axial direction (longitudinal direction) of the photosensitive drum 1.

  Further, a coupling member 70 as a drum driving force receiving portion that receives a driving force for driving the drum 1 is provided on one end side of the rotating shaft of the photosensitive drum 1. That is, the coupling member 70 is provided on one end side in the axial direction (longitudinal direction) of the photosensitive drum 1. The coupling member 70 engages with a main body coupling member 99 (FIG. 8) provided on the apparatus main body 100 in a state where the cartridge 7 is mounted on the apparatus main body 100. The coupling member 70 receives driving force from the main body coupling 99 and drives and rotates the photosensitive drum 1. The driving of the photosensitive drum 1 will be described in detail later.

(How to install process cartridge)
Next, the mounting of the process cartridge 7 to the apparatus main body 100 will be described with reference to FIGS.

  Referring mainly to FIG. 8, as described above, the process cartridge 7 (7a to 7d) is attached to or detached from the apparatus main body 100 by opening the front opening / closing door 26 of the apparatus main body, and the process cartridge insertion port 91 in the apparatus main body. Is made in a state of being largely open. The closed state of the front opening / closing door 26 with respect to the apparatus main body 100 is locked by a latch mechanism (not shown). The lock by the latching mechanism is released, and the front opening / closing door 26 including the electrostatic transfer means 5 is opened to the front side of the apparatus main body about the lower hinge shaft 27 to open the process cartridge insertion port 91 in the apparatus main body. Can be opened largely.

  Main body attachment / detachment guides 80 and 81 for guiding the process cartridge to the image forming position are attached to the inside of the side plates 31 and 32 at the process cartridge insertion port 91 of the apparatus main body 100. Four process cartridges can be mounted vertically in the insertion port 91, and a yellow cartridge insertion port, a magenta cartridge insertion port, a cyan cartridge insertion port, and a black cartridge insertion port are arranged from the lower side.

  The structure of the process cartridge mounting mechanism at each insertion port is the same as each other, and here, as an example, a description will be given of an example in which the process cartridge 7 is inserted into the lowermost yellow cartridge insertion port.

  First, in the longitudinal direction of the photosensitive drum 1 of the process cartridge 7, the right and left grip portions 82 and 83 provided at both ends of the cleaning unit 50 are held by the left and right hands, and the process cartridge 7 is held. Then, the process cartridge back side opposite to the photosensitive drum 1 side is first inserted into the insertion port 91 in the direction of arrow Q.

  The main body attaching / detaching guides 80 and 81 are provided with rough guide portions 86 and 87 for receiving the lower surfaces on both sides of the process cartridge, and the lower surface 48c of the bearing member 48 of the process cartridge 7 and the lower surface 51f of the cleaning frame 51 are respectively connected to the rough guide portions 86 and 87. Place on the rough guide portions of the guide portions 86 and 87. The body attaching / detaching guides 80 and 81 are engaged with bosses 51d and 51e provided on both side surfaces of the cleaning frame 51 of the process cartridge 7, and boss guides 88 for restricting the rotation of the process cartridge 7 within the image forming apparatus. 89 is provided.

  When the process cartridge 7 is further inserted, the bosses 51d and 51e ride on the boss guides 88 and 89 and are guided.

  An intermediate plate 93 is provided between the side plates 31 and 32 of the apparatus main body 100, and an irradiation window 95 through which the laser light L from the scanner 3 passes is provided in the intermediate plate 93. The intermediate plate 93 is provided with a cam 8 for contacting and separating the developing unit 4. The cam 8 is interlocked with a motor (not shown) provided in the main body and rotated to bring the developing roller into contact with and away from the photosensitive drum.

  As shown in FIG. 9, the process cartridge 7 is positioned in the short direction in the apparatus main body by inserting bearings 64 and 65 for supporting the photosensitive drum 1 along the guide grooves 34a to 34h. Done. The bearings 64 and 65 are pressed against the abutting surfaces 37 and 38 of the guide groove 34, whereby the position of the cartridge 7 in the short direction with respect to the apparatus main body 100 is determined. At this time, in the process cartridge 7, in the image forming apparatus, the bearings 64 and 65 are provided in the guide groove 34, and the bosses 51d and 51e on both sides of the cleaning frame 51 are provided in the body attaching / detaching guides 80 and 81, It is in the state positioned by.

  Then, the cartridge drive gear 71 provided on the process cartridge 7 side is engaged with a main body development drive gear (not shown) on the apparatus main body side.

  The process cartridge 7 is inserted into the magenta cartridge insertion port, cyan cartridge insertion port, and black cartridge insertion port in the same manner as the process cartridge 7 is inserted into the lowermost yellow cartridge insertion port.

Next, the opened front opening / closing door 26 is sufficiently closed with respect to the apparatus main body 100, and the closed state is locked by a latching mechanism (not shown). By means of interlocking with the closing operation by closing the front opening / closing door 26,
1) Press positioning in the short direction of each process cartridge 7 in the apparatus main body 100 2) Movement of each process cartridge 7 to the opening position of the shutter member 101 3) Apparatus main body 100 with respect to the coupling member 70 of each process cartridge 7 The main body coupling member 99 on the side is engaged.

  In the above, the pressing positioning in the short direction of each process cartridge 7 in 1) is performed by a pressing member 30 interlocked with the opening / closing mechanism of the front opening / closing door 26 including the electrostatic transfer means 5 inside as shown in FIG. . The pressing member 30 is rotatably attached to a caulking shaft 36 that is crimped to the side plate 31. The pressing member 30 is engaged with the connecting member 29, and the connecting member 29 is interlocked with the opening / closing operation of the front opening / closing door 26. When the front opening / closing door 26 is opened, that is, when the process cartridge 7 is detachable, the pressing member 30 is at the position 30a. At this position, the pressing member 30 is in a retracted position, and the pressing member 30 does not contact the process cartridge 7 when the process cartridge 7 is inserted. After the process cartridge 7 is inserted, the connecting member 29 operates in the direction of arrow R along with the operation of closing the front opening / closing door 26 (in the direction of arrow T). In conjunction with this, the pressing member 30 moves to the position 30b and presses the slope 51s (51t) of the cleaning frame 51 provided in the vicinity of the bearing 64 (65) in the direction of the arrow S. As a result, the process cartridge 7 is positioned in the lateral direction within the image forming apparatus main body. A similar mechanism is also provided on the side plate 32 side, and is configured to press both longitudinal sides of the process cartridge 7 with the pressing member 30.

  The movement of each process cartridge 7 in the above 2) to the opening position of the shutter member 101 is interlocked with the closing operation of the main body door, and the interlocking member (not shown) operates the shutter opening / closing member 102 (FIG. 3) of the process cartridge. Is completed before the front opening / closing door 26 is completely closed by the apparatus main body 100, and in the state where the front opening / closing door 26 is completely closed by the apparatus main body 100, the photosensitive drum 1 of each process cartridge 7. The transfer belt 11 is in contact with the externally exposed surface (FIG. 1).

  The main body coupling member 99 of 3) is moved toward the coupling member 70 of each process cartridge 7 in conjunction with the front opening / closing door 26. When each process cartridge 7 is attached to the apparatus main body 100, when a driving force from a drive motor (not shown) on the apparatus main body 100 is transmitted to the main body coupling member 99, the main body coupling member 99 rotates, and the coupling is performed. Engagement with the member 70 transmits drive to the coupling member 70 so that the photosensitive drum 1 of each process cartridge 7 can be driven to rotate counterclockwise in FIG. Further, in conjunction with the rotation of the photosensitive drum 1, the toner feeding mechanism 52 of the removed toner chamber 53 can be driven via a gear train (not shown).

  Since the cartridge drive gear 71 of each process cartridge 7 is engaged with a main body development drive gear (not shown) on the apparatus main body 100 side, the cartridge drive gear 71 receives a drive force from the main body drive gear side, and this cartridge drive gear. The developing roller 40, the toner transport mechanism 42, and the toner supply roller 43 of each process cartridge 7 can be driven by a rotation of 71 through a gear train (not shown).

  In the laser scanning exposure of the photosensitive drum 1 on the process cartridge 7 side by the scanner unit 3 on the apparatus main body 100 side, the output laser light L of the scanner unit 3 is developed with the cleaning unit 50 of the process cartridge 7 from the irradiation window 95 of the intermediate plate 93. This is done by entering the exposure gap 55 between the units 4 (FIGS. 2 and 4).

  Removal of each process cartridge 7 from the apparatus main body 100 is performed in the reverse procedure to that in the above mounting. In other words, the front opening / closing door 26 is closed with respect to the apparatus main body 100 by unlocking a locking mechanism (not shown), and the front opening / closing door 26 including the electrostatic transfer means 5 is moved around the lower hinge shaft 27 to form an image forming apparatus. Push down on the front side of the main unit. By means of interlocking with the opening operation of the front opening / closing door 26, the pressing by the pressing member 30 of each process cartridge 7 is released. Further, the engagement of the main body coupling member 99 on the apparatus main body 100 side with respect to the coupling member 70 of each process cartridge 7 is released. Further, the shutter member 101 of each process cartridge 7 moves to the closed position. In this state, each process cartridge 7 can be taken out from the apparatus main body 100 by grasping the grip portions 82 and 83 of the process cartridge 7 with the left and right hands and pulling out the process cartridge 7 in the direction opposite to that at the time of mounting.

(Photosensitive drum drive configuration)
Next, driving of the photosensitive drum will be described. 10 and 11 are diagrams for explaining the drive unit 103 that drives the photosensitive drum from the image forming apparatus.

  In the driving unit 103, driving units 103Y, 103M, 103C, and 103Bk for driving the photosensitive drums 1 of Y, M, C, and Bk colors are positioned and fixed on the driving frame 104 with high accuracy. The drive unit 103 includes a drum motor 39 fixed to the drive frame 104, a pinion 46 fixed to the motor shaft of the motor 39, and an intermediate gear 97 that meshes with the pinion 46 and the drum drive gear 98 and is rotatably supported. A drum driving gear 98, a main body bearing 49 that supports the drum driving gear 98, and a main body coupling member 99 formed at the tip of the drum driving gear 98.

  Next, a connection configuration between the photosensitive drum 1 and the drive unit 103 will be described with reference to FIGS. After the user mounts the process cartridge 7 on the main body of the image forming apparatus, the rotating cam 128 rotates in conjunction with the rotating operation of bringing the electrostatic transfer means (not shown) into contact with the photosensitive drum 1 and is connected to the rotating cam 128. When the counter rotating cam 129 to be moved is thrust along with the drum drive gear 98 in the axial direction of the photosensitive drum 1 by the urging force of the return spring 62, the main body coupling recess 99a formed at the tip of the drum drive gear 98 is photosensitive. The drum drive gear 98 is positioned with respect to the photosensitive drum 1 by connecting to and engaging with a coupling member triangular portion 70a having a twisted regular triangular prism shape formed on the cartridge coupling member 70 at the end of the body drum unit. While being fixed, the axis of the drum drive gear 98 is arranged on the same straight line with respect to the photosensitive drum 1.

  The main body coupling recess 99a is inserted into and extracted from the coupling member triangular portion 70a, which is a hole serving as a twisted regular triangular prism, in the axial direction. A main body central shaft 108 for positioning the main body coupling member 99 in the longitudinal direction is integrally provided at the center of the main body coupling member 99. The main body central shaft 108 is inserted into a central hole 70d provided in the coupling 70, and the end portion 61a of the rotary shaft 61 for transmitting the drive transmission of the end portion of the main body central shaft 108 and the coupling member 70 to the drum. Abut. The main body coupling member 99 is positioned in the longitudinal direction, and the main body coupling member 99 is pressed against the process cartridge by the return spring 62.

  As shown in FIGS. 14 and 15, the main body coupling recess 99 a is provided with a key groove 99 c on one side 99 b of a hole serving as a twisted regular triangular prism, and provided on one side 70 b of the regular triangular prism of the coupling member 70. The phase positioning rib 70c is configured to be engaged. The phase positioning rib 70c is configured so that it can be inserted / removed only in one rotation / phase so that one side 99b of the regular triangular prism hole of the main body coupling member 99 and one side 70b of the regular triangular prism of the coupling 70 can be surely engaged. Until the phases of the phase positioning rib 70c and the keyway 99c coincide with each other, the coupling member 70 and the main body coupling member 99 do not engage with each other even if rotation starts.

  When the phase positioning rib 70c and the keyway 99c are out of phase and the coupling member triangular portion 70a and the main body coupling recess 99a are not connected, the end surface 70g of the coupling member triangular portion 70a is the end surface 99d of the main body coupling portion 99. To stop the drum drive gear 98 from moving inward in the longitudinal direction of the image forming apparatus against the urging force of the return spring 62. Then, after the process cartridge 7 is mounted, the phase positioning rib 70c and the keyway 99c are instantaneously engaged when the phases of the phase positioning rib 70c and the keyway 99c coincide with each other when the image forming apparatus main body is rotated forward.

  As described above, in the drum driving gear 98 and the photosensitive drum 1, the phases of the phase positioning rib 70c and the key groove 99c coincide with each other, and the main body coupling recess 99a and the coupling member triangular portion 70a engage with each other. As a result, the positioning and fixing are performed for the first time, and the rotational driving force by the drum motor 39 as the driving source is transmitted to the coupling member triangular portion 70a. At this time, the rotational phase of the drum drive gear 98 and the rotational phase of the coupling member triangular portion 70a are uniquely determined by the relationship of one rotation and one phase.

  Here, the drum unit configuration will be described with reference to FIGS.

  The rotation shaft 61 that serves as the rotation center of the photosensitive drum 1 is provided with pin holes 61c and 61b into which the coupling pin 67 and the drum flange pin 68 are inserted, so that the rotation phases of the hole positions coincide with each other. It is configured. The coupling member 70 has a coupling member triangular portion 70a at the end, and pin holes 70e and 70f into which the coupling pins 67 are inserted. The pin hole 70e and the pin hole 70f are provided at positions facing each other across the center hole 70d into which the rotary shaft 61 is fitted, and both holes are round holes that are fitted without any play with the outer diameter of the coupling pin 67. Shape.

  The coupling member 70 is configured to transmit the rotational driving force to the rotating shaft 61 via the coupling pin 67 and transmit the driving to the photosensitive drum 1. Further, the drive point of the coupling member 70 and the rotating shaft 61 is configured to transmit the drive at two points of pin holes 70e and 70f. Further, the rotational phase of the phase positioning rib 70c formed in the coupling member triangular portion 70a and the rotational phase of the pin hole 70e described above are uniquely determined in the coupling member 70.

  The drum flange member 60 provided at the end of the photosensitive drum 1 is provided with pin holes 60a and 60b into which the drum flange pin 68 is inserted. This pin hole 60a has an outer diameter of the drum flange pin 68 on the opposite side across the round hole 60a that fits with the outer diameter of the drum flange pin 68 and the center hole 60d with which the rotary shaft 61 is fitted. Is provided with a square hole portion 60b that contacts only on the downstream side in the rotational direction. As shown in FIG. 17, the upstream side of the hole 60 b in the rotational direction has a shape that does not contact the outer diameter of the drum flange pin 68. When the coupling member 70 rotates in the direction of arrow U, the rotation transmission driving force is transmitted to the drum flange pin 68 via the rotation shaft 61. The drum flange pin 68 comes into contact with the round hole 60a to rotate the drum flange member 60, and at the same time, comes into contact with the contact part 60c on the downstream side in the rotation direction of the square hole 60b.

  As shown in FIG. 18, when the photosensitive drum 1 rotates and a load torque is applied, the coupling member 70 and the rotating shaft 61 are coupled to the coupling pin 67 at two locations, and are driven from the image forming apparatus main body. The received rotational driving force of the coupling member 70 becomes a driving force of F1 generated in the pin hole 70e and a couple F2 generated in the opposing pin hole 70f. These driving forces are coupled at the two locations of the pin holes 70e and 70f and the coupling pin 67, so that the rotational driving force becomes substantially the same driving force (F1≈F2), and the rotary shaft 61 is rotated by the drive transmission at these two locations. To drive.

  As shown in FIG. 19, the rotational driving force from the coupling member 70 is transmitted to the photosensitive drum 1 through the drum flange member 60. The rotating shaft 61 and the drum flange member 60 are rotationally driven in the direction of the arrow U by the drum flange pin 68, the drum flange portion round hole portion 60a, and the square hole portion 60b. Here, the rotational driving force F3 generated in the round hole portion 60a and the rotational driving force F4 generated in the contact portion 60c of the square hole portion 60b act on the drum flange member 60.

  Here, since the round hole 60a which is the first drive transmission is coupled with the drum flange pin 68 without any play, even if the reaction force of the driving force F3 acts on the drum flange pin 68, the round hole The deformation of the 60a and the drum flange pin 68 hardly occurs, and there is little loss of drive transmission. The second drive transmission point is the contact portion 60c that contacts the drum flange pin 68 of the square hole portion 60b. When a reaction force of the driving force F4 occurs at the contact portion 60c, a gap 60e is provided on the opposite side of the contact portion 60c across the drum flange pin 68, so that the reaction force causes the drum flange pin 68 to move. The structure is such that bending or the like occurs and the driving force is slightly lost. Here, the rotational driving force has a relationship of F3> F4. With this configuration, the rotation cycle of the photosensitive drum 1 coincides with the position of the round hole portion 70a which is the first driving point at which a larger rotational driving force is applied. That is, in the photosensitive drum unit, the rotational phase can be uniquely determined by the phase positioning rib 70c formed in the coupling member triangular portion 70a and the drum flange portion round hole portion 60a.

  Further, as described above, the coupling member triangular portion 70a and the main body coupling concave portion 99a have a configuration in which the rotational phase is uniquely determined by the phase positioning rib 70c and the key groove 99c in one rotation and one phase. The rotational phases of the drum drive gear 98, the main body coupling member 99, the coupling member 70, the rotating shaft 61, the drum flange member 60, and the photosensitive drum 1 can be uniquely determined. For example, the drum drive gear 98, the main body coupling member 99, the coupling member 70, the rotating shaft 61, the drum flange member 60, and the photosensitive drum even when the process cartridge 7 is detached from the main body of the image forming apparatus and remounted. The rotational phase of 1 can be matched before and after mounting.

  Also, as shown in FIGS. 12 to 14, the drum drive gear 98 is provided with a phase detection rib 72 so that the rotational phase can be detected. The phase detection rib 72 is provided with slit portions 72 a and 72 b having different slit widths, and a detection portion 78 separately installed in the image forming apparatus main body passes through the slit portions 72 a and 72 b while the drum drive gear 98 is rotating. By detecting, the rotation phase of the drum drive gear 98 can be detected instantaneously. When the pre-rotation is stopped when the image forming apparatus is activated, the detection unit 78 detects the rotation phases of the drum drive gears 98 for the four colors so that the rotation phases of the drum drive gears coincide with each other during printing. By controlling the rotation of the motor 39 so that each drum drive gear 98 is stopped at a position where a predetermined angle is shifted in advance, the rotation of the photosensitive drums 1 for the four colors is started when the next print job is started. The color shift of the drum cycle in the paper conveyance direction caused by the phase shift can be reduced without causing the phase shift.

  The effectiveness of the image forming apparatus configured as in the conventional example and the image forming apparatus of the present invention described above can be explained as the difference shown in FIG. FIG. 20A is a diagram showing the rotational fluctuations of the four photosensitive drums 1 in the conventional image forming apparatus. The horizontal axis represents time, and the vertical axis represents the rotational fluctuation of the photosensitive drum. The print start point in the rotation phase of each color is set to 0 °. In this case, the rotational phase of the photosensitive drum 1 at the print start point of each color does not match, and a difference in amplitude amount at that position occurs as a color shift. This is because the rotation phase of the drum flange member 60 described above is not uniquely determined with respect to the rotation shaft 61, the coupling member 70, and the main body coupling member 99, and the motor 39 is detected by detecting the phase of the main body coupling member 99. This is because the phase of the photosensitive drum 1 of each color has been varied even if the control is performed.

  On the other hand, FIG. 20B shows a case where the driving point for transmitting the rotational driving force to the drum flange member 60 and the photosensitive drum 1 is coupled at one place of the round hole 70a, or the coupling member 70 and the rotating shaft. 61 is coupled at one location, and the rotational phases of the drum flange member 60, the rotary shaft 61, the coupling member 70, and the main body coupling member 99 are uniquely determined by the phase positioning rib 70c and the drum flange pin 68. FIG. 6 is a diagram showing rotation fluctuations of the photosensitive drum 1 in the case of a determined configuration. In this configuration, the rotational phases of the photosensitive drums 1 at the printing start points of the respective colors are completely coincident with each other, so that no color shift due to the phase difference occurs on the output image, and a relatively good color is obtained. A deviation level can be realized. However, as described above, the driving point for rotationally driving the photosensitive drum 1 is a coupling of the coupling member 70 and the rotating shaft 61 and the coupling of the drum flange member 70 and the rotating shaft 61 is one. In FIG. 2, since a large force for moving the photosensitive drum 1 acts, an effective rotational driving force cannot be obtained, and the magnitude, that is, the amplitude of the rotational fluctuation of the photosensitive drum 1 increases. Therefore, as shown in FIG. 20B, if there is variation in the magnitude of the rotational fluctuation of each color photosensitive drum 1, the amplitude of the rotational fluctuation itself is large, and color misregistration may still occur.

  On the other hand, FIG. 20C shows the first embodiment described above, and the coupling between the drum flange member 60 and the rotary shaft 61 is the first drive point (drum flange member round hole) that determines the rotational phase. Part 60a) and an auxiliary second driving point (drum flange member abutting part 60c) for generating a driving force smaller than the rotational driving force by the first driving point, are provided in the coupling member 70 and the rotary shaft 61. Shows a case where the two joints are joined with round holes 70e and 70f having no play so that a difference in rotational driving force is unlikely to occur. Since the rotational phase of the photosensitive drum 1 at the printing start point of each color is the same and the amplitude due to the rotational fluctuation in the coupling member 70 is reduced, the output image further rotates due to the phase difference. Color shift due to fluctuations can be minimized.

  In the first embodiment, the coupling member 70 and the rotary shaft 61 are coupled using the coupling pin 67. In the present embodiment, as shown in FIG. 21, chamfered portions 61g and 61h are provided at the portion of the rotating shaft 61 to be inserted into the coupling member 70. Further, the coupling member 70 is provided with contact surfaces 70g and 70h that contact the coupling member 70, and drive transmission is performed at these two locations. A prevention pin 69 that prevents the coupling member 70 from falling off the rotating shaft 61 is inserted into an insertion hole 70 i provided in the coupling member 70. The inserted prevention pin 69 is inserted into a prevention hole 61 i provided in the rotating shaft 61 to prevent the coupling member 70 from falling off the rotating shaft 61. Here, the prevention pin 69 is inserted without any play in the insertion hole 70i, and the prevention hole 61i is a hole that is slightly larger than the outer diameter of the prevention pin 69 so that it does not come into contact with the prevention pin 69 during rotational driving. .

  In the first embodiment, it has been described above that the drive transmission force of the coupling member 70 and the rotary shaft 61 is performed in the two holes and the coupling pin 67. The two drive transmission points are uniquely determined as the drive transmission points of the drum flange member 60, but as shown in FIG. 22, phase determination ribs 70 c that determine the phase of the coupling member 70 are provided on the drum flange member 60. You may use the structure press-fit in the front-end | tip part of the rotating shaft 61 in the state which aligned the round hole part 60a.

  According to the present embodiment, the following effects can be achieved.

  1) The photosensitive drum unit is configured such that the rotational phases of the drum flange member 60, the rotary shaft 61, and the coupling member 70 that rotationally drive the photosensitive drum 1 are simultaneously determined, and the plurality of photosensitive members. A plurality of drum drive gears 98 of the image forming apparatus main body arranged coaxially with the rotary shaft 61 for rotating the drum, a main body coupling member 99 provided at the end of the drive gear, and a cup of the process cartridge Since the ring member 70 is configured such that the coupling is engaged only at one rotation and one phase, even if rotation fluctuations occur in a plurality of photosensitive drums, only the rotation phase of the drive gear can be matched. At the same time, the rotational phases of the photosensitive drums can be matched.

  2) A first driving point for transmitting the rotational driving force of the rotary shaft 61 to the drum flange member 60 and determining the rotational phase thereof, and an auxiliary for generating a driving force smaller than the rotational driving force by the first driving point By providing such a second drive point, the rotational fluctuation of the photosensitive drum 1 itself can be stably reduced. Further, in the transmission of the rotational driving force between the coupling member 70 and the rotating shaft 61, the rotational fluctuation is hardly caused by transmitting the rotational driving at two places. Therefore, the rotational fluctuation amplitude of the photosensitive drum can be reduced, and the color shift in the paper transport direction can be reduced.

3) Modified Configuration Example, etc. In the above-described embodiment, the cup engaged with the rotation-preventing shape in which the rotating shaft 61 shown in FIG. The same effect can be obtained by using the ring member 70.

  Further, the same effect can be obtained by using the configuration in which the coupling member 70 is press-fitted into the rotating shaft 61 shown in FIG. 22 in the coupling between the coupling member 70 on the process cartridge 7 side and the rotating shaft 61 in the above-described embodiment.

1 is an explanatory cross-sectional view illustrating an overall schematic configuration of an electrophotographic image forming apparatus in Embodiment 1. FIG. 3 is a cross-sectional explanatory diagram of a process cartridge according to Embodiment 1. FIG. FIG. 3 is a schematic perspective view of a process cartridge according to the first embodiment (No. 1). FIG. 3 is a perspective model view (part 2) of the process cartridge according to the first exemplary embodiment. FIG. 3 is a perspective model view (No. 1) of the developing unit constituting the process cartridge according to the first exemplary embodiment. FIG. 6 is a perspective schematic view (No. 2) of the developing unit constituting the process cartridge in Embodiment 1. FIG. 6 is an explanatory diagram of a developing unit separation operation in Embodiment 1. 6 is an explanatory diagram of a process cartridge mounting method in Embodiment 1. FIG. FIG. 6 is an explanatory diagram of a short-side positioning mechanism in the apparatus main body of the process cartridge according to the first embodiment. FIG. 3 is a unit configuration diagram illustrating a configuration of a drive unit according to the first embodiment. It is a side view which shows the structure of the drive unit in Example 1. FIG. FIG. 3 is a configuration diagram illustrating a connection form between a drive unit and a photosensitive drum in Embodiment 1. FIG. 3 is a configuration diagram illustrating a connection form between a drive unit and a photosensitive drum in Embodiment 1. 3 is a perspective view illustrating a main body coupling shape of the image forming apparatus main body in Embodiment 1. FIG. FIG. 3 is a perspective view illustrating a coupling shape of the process cartridge according to the first exemplary embodiment. FIG. 3 is a perspective view illustrating the shape of a photosensitive drum unit in Embodiment 1. FIG. 3 is a detailed diagram illustrating the shape of the photosensitive drum unit according to the first exemplary embodiment. FIG. 3 is an explanatory diagram illustrating a stress relationship acting on a coupling member of the photosensitive drum unit according to the first exemplary embodiment. FIG. 6 is an explanatory diagram illustrating a stress relationship acting on a drum flange member of the photosensitive drum unit according to the first exemplary embodiment. 6 is a graph illustrating the effect of reducing color misregistration due to the drive connection configuration in Example 1; FIG. 6 is a perspective view illustrating a photosensitive drum unit in Embodiment 2. FIG. 6 is a perspective view illustrating a photosensitive drum unit according to Embodiment 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging means 3 Scanner unit 4 Developing means 5 Electrostatic transfer means 6 Cleaning means 7 Process cartridge 8 Contacting / separating cam (force applying member)
DESCRIPTION OF SYMBOLS 11 Transfer belt 12 Transfer roller 17 Cassette 18 Feed roller 19 Registration roller pair 20 Fixing part 22 Electrostatic adsorption roller 26 Opening / closing door 29 Connecting member 30 Holding member 31 Left side plate 32 Right side plate 39 Drum motor 40 Developer roller 41 Developer frame body 42 Developer Conveying Mechanism 43 Developer Supply Roller 44 Developing Blade 45 Developing Frame Body 46 Pinion 47, 48 Bearing Member 50 Cleaning Unit 51 Cleaning Frame Body 51d, 51e Boss (Regulator)
52 Toner feeding mechanism 54 Pressing spring 61 Rotating shaft 62 Return spring 64, 65 Bearing 67 Coupling pin 68 Drum flange pin 70 Coupling member 71 Cartridge drive gear 80, 81 Main body attaching / detaching guide 84 Main body pressing means 86, 87 Rough guide portion 88 , 89 Boss guide 90 Tension spring 91 Cartridge insertion port 93 Intermediate plate 98 Drum drive gear 99 Main body coupling member 100 Main body 101 Shutter member 102 Shutter opening / closing member 103 Drive unit 104 Drive frame 108 Main body axis 128 Rotating cam 129 Counter side rotation cam

Claims (4)

A photosensitive drum;
A rotation axis passing through the center of the photosensitive drum;
A drum flange member for transmitting the drive of the rotating shaft to the photosensitive drum;
A process cartridge that is provided at one end of the rotating shaft and has a coupling member that is driven by the electrophotographic image forming apparatus main body;
A rotational driving force of the rotating shaft is transmitted to the drum flange member, and a first driving point for determining a rotational phase of the photosensitive drum is opposed to the first driving point, and the rotational driving of the first driving point is performed. A second driving point for transmitting a smaller rotational driving force to the drum flange member,
The coupling member is coupled to the rotating shaft at a position that matches the phase of the driving point of the rotating shaft and the drum flange member, and at a position that matches the phase of the main body coupling of the electrophotographic image forming apparatus main body. A process cartridge having a phase determining portion to be engaged.   The coupling member is coupled to the rotating shaft at two points, and the coupling part is disposed at a position in phase with the first driving point and the second driving point. Process cartridge according to.   The phase determining portion of the coupling member is characterized in that the coupling member is press-fitted into the rotating shaft at a position coincident with either the first driving point or the second driving point of the drum flange. 2. The process cartridge according to 1. A photosensitive drum;
A rotation axis passing through the center of the photosensitive drum;
A drum flange member for transmitting the drive of the rotating shaft to the photosensitive drum;
A process cartridge that is provided at one end of the rotating shaft and has a coupling member that is driven by the electrophotographic image forming apparatus main body;
A rotation driving force of the rotation shaft is transmitted to the drum flange member, and a first driving point for determining a rotation phase of the photosensitive drum, and a rotation driving force smaller than the rotation driving of the first driving point are applied to the drum. A second drive point for transmitting to the flange member;
A main body coupling member that engages with a coupling member that is coupled by matching a phase of a driving point between the rotating shaft and the drum flange member and a phase of a coupling portion of the rotating shaft and the coupling; A color electrophotographic image forming apparatus, wherein the ring member and the main body coupling member are configured such that the coupling engages only in one rotation and one phase.

Images