Patent Publication Number: US-2022236685-A1

Title: Drum unit, process cartridge and image forming apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to an image forming apparatus for forming an electrophotographic image, a process cartridge, and a drum unit. 
     BACKGROUND ART 
     In an electrophotographic image forming apparatus, a structure is known in which elements such as a photosensitive drum and a developing roller as rotatable members contributable to image formation are integrated as a cartridge, and the cartridge can be mounted to and dismounted from the main assembly of the image forming apparatus (hereinafter referred to as apparatus main assembly). Here, in order to rotate the photosensitive drum in the cartridge, it is desirable to transmit the driving force from the main assembly of the device. At that time, it is known that a coupling member on the cartridge side is engaged with a driving force transmission portion such as a drive pin on the side of the main assembly to transmit the driving force. 
     Here, a structure of a cartridge that is removable in a predetermined direction substantially perpendicular to the rotation axis of the photosensitive drum is known. Japanese Laid-open Patent Application No. 2008-233867 discloses a structure in which a coupling member provided at the end portion of the photosensitive drum can incline relative to the rotation axis of the photosensitive drum. It is known that by doing so, a coupling member mounted on a cartridge is engaged with a driving pin provided in the main assembly of the apparatus, and a driving force is transmitted from the apparatus main assembly to the cartridge 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     It is an object of the present invention to develop the above-mentioned conventional technique. 
     Means for Solving the Problem 
     According to an aspect of the present invention, there is provided a drum unit usable with a process cartridge, said drum unit comprising a photosensitive drum having an axis L 1 ; and a coupling member having an axis L 2  and connected to an end portion of said photosensitive drum, said coupling member being provided with a projection extending toward an end portion of said coupling member, wherein said coupling member is movable along the axis L 2  between a first position, and a second position in which said projection is closer to said photosensitive drum than in the first position, wherein said projection is provided with a force receiving portion for receiving a rotational force and an outer surface facing away from the axis L 2 , and wherein at least a part of the outer surface is more distant from the axis L 2  as is further from said photosensitive drum in a direction of the axis L 1 . 
     Effect of the Invention 
     The above-described conventional technique can be developed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of an image forming apparatus. 
         FIG. 2  is a sectional view of the cartridge. 
         FIG. 3  is an exploded perspective view of the cartridge. 
       Part (a) and part (b)  FIG. 4  illustrate mounting and dismounting of the cartridge. 
       Part (a) of  FIG. 5  and part (b) of  FIG. 5  are side views of the coupling member, and  FIG. 5  (c) is a perspective view of the coupling member. 
       Part (a) of  FIG. 6  and part (c) of  FIG. 6  are perspective views of the drum gear unit, and part (b) of  FIG. 6  and part (d) of  FIG. 6  are sectional views of the drum gear unit. 
       Part (a 1 ) of  FIG. 7 , part (a 2 ) thereof, part (a 3 ) thereof, and part (a 4 ) thereof illustrate the gear unit, and parts (b 1 ), (b 2 ), (b 3 ) and (b 4 ) of  FIG. 7  are sectional views of the drum gear units. 
         FIG. 8  illustrates a modification of the Embodiment 1. 
       Part (a) of  FIG. 9 , part (b) thereof, part (c) thereof, part (d) thereof and part (e) thereof are perspective views of a drum gear unit. 
       Part (a) of  FIG. 10 , part (b) of  FIG. 10  and part (c) of  FIG. 10  are exploded perspective views of a cleaning unit. 
       Part (a) of  FIG. 11  and part (b) of  FIG. 11  are perspective views of the cartridge. 
       Part (a) of  FIG. 12 , part (b) of  FIG. 12 , part (c) of  FIG. 12  and part (d) of  FIG. 12  illustrate the operation of the drum gear unit. 
       Part (a 1 ) of  FIG. 13 , part (a 2 ) thereof, part (a 3 ) thereof, and part (a 4 ) thereof illustrate a drum gear unit, and part (b 1 ) of  FIG. 13 , part (b 2 ) thereof, part (b 3 ) thereof and part (b 4 ) thereof are sectional views of the drum gear unit. 
       Part (a) of  FIG. 14  and part (b) of  FIG. 14  are perspective views of the drum gear unit, and part (c) of  FIG. 14  and part (d) of  FIG. 14  are sectional views of the drum gear unit. 
       Part (a) of  FIG. 15  and part (b) thereof illustrate the drum gear unit. 
       Part (a) of  FIG. 16 , part (b) thereof, part (c) thereof and part (d) thereof illustrate the drum gear unit. 
       Part (a) of  FIG. 17 , part (b) of  FIG. 17  and part (c) of  FIG. 17  illustrate the drum gear unit. 
       Part (a 1 ) of  FIG. 18 , part (a 2 ) thereof, and part (a 3 ) thereof show the drum gear unit, and part (b 1 ) of  FIG. 18 , part (b 2 ) thereof and part (b 3 ) thereof are sectional views of a drum gear unit. 
       Part (a) of  FIG. 19 , part (b) thereof, part (c) thereof and part (d) thereof illustrate the drum gear unit. 
       Part (a) of  FIG. 20  and part (b) of  FIG. 20  illustrate the drum gear unit. 
       Part (a) of  FIG. 21  and part (b) of  FIG. 21  illustrate the drum gear unit. 
       Part (a) of  FIG. 22 , part (b) of  FIG. 22  and part (c) of  FIG. 22  illustrate the drum gear unit. 
       Part (a 1 ) of  FIG. 23 , part (a 2 ) thereof, and part (a 3 ) thereof show a drum gear unit, and part (b 1 ) of  FIG. 23 , part (b 2 ) thereof, and part (b 3 ) thereof are sectional views of a drum gear unit. 
       Part (a) of  FIG. 24 , part (b) of  FIG. 24  and part (c) of  FIG. 24  illustrate the coupling member, and part (d) of  FIG. 24 , part (e) of  FIG. 24  and part (f) of  FIG. 24  are sectional views of the coupling member. 
       Part (a) of  FIG. 25  is an illustration illustrating a modified example of the coupling member, and  FIG. 25  (b) is a sectional view illustrating a modified example of the coupling member. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, embodiments to which the present invention is applied will be described in conjunction with the drawings. 
     Here, an image forming apparatus (an image forming apparatus for forming an electrophotographic image) employing an electrophotographic method is referred to as an electrophotographic image forming apparatus. The electrophotographic method is a method of developing an electrostatic image formed on a photosensitive member with toner. Here, the developing method may be a one-component developing method, a two-component developing method, a developing method such as dry developing or the like. In addition, the electrophotographic photosensitive drum (electrophotographic photosensitive drum) is used for an electrophotographic image forming apparatus, and has a structure in which a photosensitive member (photosensitive layer) is provided on a cylindrical surface layer of a drum-shaped cylinder. 
     Here, a charging roller, a developing roller, etc. relating to image formation and acting on the photosensitive drum is called a process means. In addition, a cartridge comprising a photosensitive member or process means (cleaning blade, developing roller, and so on) related to image formation is called a process cartridge. In the embodiment, a process cartridge in which a photosensitive drum, a charging roller, a developing roller, and a cleaning blade are integrated into a unit will be described. 
     In the embodiment, a laser beam printer will be taken among electrophotographic methods used for wide variety of applications such as multifunction peripheral, FAX, printer, and so on. The reference numerals in the examples are used for referring to the drawings and do not limit the constitution of the present invention. The dimensions and so on in the examples are used for explaining the relationships clearly and do not limit the structure of the present invention. 
     The longitudinal direction of the process cartridge in the embodiment is a direction substantially perpendicular to the direction in which the process cartridge is mounted to and dismounted from the main assembly of the electrophotographic image forming apparatus. The longitudinal direction of the process cartridge is parallel to the rotation axis of the electrophotographic photosensitive drum (the direction crossing the sheet feeding direction). In the longitudinal direction, the side where the photosensitive drum receives rotational force from the image forming apparatus main assembly of the process cartridge is a driving side (driven side), and the opposite side thereof is a non-driving side. In addition, without specific reference, the upper (upper side) and the lower (lower side) are based on the direction of the gravity in the state that the image forming apparatus is installed. 
     Embodiment 1 
     The laser beam printer of this embodiment will be described with reference to the drawings. The cartridge in this embodiment is a process cartridge in which ‘a photosensitive drum as a photosensitive member (image bearing member/rotatable member)’ and ‘a’ developing roller, a charging roller, a cleaning blade as a process means are integrated. This cartridge is dismountably mountable relative to the main assembly of the machine. Here, gears, photosensitive drums, flanges, developing rollers, etc. are provided in the cartridge as rotatable members/rotating members which receive rotation force from the main assembly of the operation to rotate. 
     Referring to  FIG. 1 , the structure of a laser beam printer as an electrophotographic image forming apparatus and an image forming process will be described below. Then, the detailed structure of the process cartridge will be explained referring to  FIG. 2  and  FIG. 3 . 
     (Laser Beam Printer and Image Forming Process) 
       FIG. 1  is a cross-sectional view of a laser beam printer main assembly A (hereinafter referred to as apparatus main assembly A) and a process cartridge (hereinafter referred to as cartridge B) which is an electrophotographic image forming apparatus. Also,  FIG. 2  is a sectional view of the cartridge B. 
     Hereinafter, the apparatus main assembly A refers to a part of a laser beam printer as an electrophotographic image forming apparatus excluding a removable cartridge B. 
     First, referring to  FIG. 1 , the structure of a laser beam printer as an electrophotographic image forming apparatus will be described. 
     The electrophotographic image forming apparatus shown in  FIG. 1  is a laser beam printer using an electrophotographic technique in which a cartridge B is dismountably mountable to (dismountable from) the apparatus main assembly A. When the cartridge B is mounted in the apparatus main assembly A, the cartridge B is disposed below the laser scanner unit  3  as the exposure means (exposure device). 
     Further, below the cartridge B, there is provided a sheet tray  4  containing a sheet P as a recording medium (sheet material) as an image forming object (object) on which the image forming apparatus forms an image. 
     Further, in the main assembly A of the apparatus, a pickup roller  5   a , a pair of feeding rollers  5   b , a pair of feeding rollers  5   c , a transfer guide  6 , a transfer roller  7 , a feeding guide  8 , a fixing device  9 , a pair of discharge rollers  10 , and a discharge tray  11  are provided in the order named from the upstream side along the feeding direction X 1  of the sheet P. The fixing device  9  as the fixing means includes the heating roller  9   a  and the pressure roller  9   b.    
     Next, referring to  FIGS. 1 and 2 , the outline of the image forming process will be described. 
     Based on the print start signal, the drum cylinder  62  as a rotatable photosensitive drum bearing developer is rotated at a predetermined circumferential speed in the direction of arrow R (hereinafter referred to as rotational direction R)). 
     The charging roller  66  to which the bias voltage is applied contacts the outer circumferential surface of the drum cylinder  62  and uniformly charges the outer circumferential surface of the drum cylinder  62 . 
     The laser scanner unit  3  as the exposure means outputs the laser light L corresponding to the image information inputted to the laser printer. The laser beam L scans and exposes the outer circumferential surface of the drum cylinder  62  through the exposure window  74  on the upper surface of the cartridge B. By this, a part of the charged drum cylinder  62  is neutralized, so that an electrostatic image (electrostatic latent image) is formed on the surface of the photosensitive drum. 
     On the other hand, as shown in  FIG. 2 , in a developing unit  20  as a developing device, the developer (hereinafter referred to as toner T) in a toner chamber  29  is fed to a feeding screw  43  and is stirred and fed by rotation, and is fed to a toner supply chamber  28 . 
     The toner T as a developer is carried on a surface of a developing roller  32  as a developing means (process means, rotatable member) by a magnetic force of a magnet roller  34  (fixed magnet). The developing roller  32  functions as a toner carrying member (developer carrying member, developing member) which carries and feeds the developer to the developing area to develop the electrostatic image formed on the drum cylinder  62 . The toner T fed to the developing area is regulated in the layer thickness on the peripheral surface of the developing roller  32  by a developing blade  42 . The toner T is triboelectrically charged between the developing roller  32  and the developing blade  42 . 
     In this manner, the toner T carried by the developing roller  32  develops (visualizes) the electrostatic image formed on the drum cylinder  62 . The drum cylinder  62  rotates in the rotational direction R while carrying the toner (toner image) developed on its surface. The drum cylinder  62  is an image bearing member which carries a toner image. 
     As shown in  FIG. 1 , in timed relation with the output timing of the laser beam L, the pickup roller  5   a , the pair of feeding rollers  5   b , and the pair of feeding rollers  5   c  feed the sheet P stored in the lower portion of the apparatus main assembly A from the sheet tray  4 . 
     Then, the sheet P is supplied to the transfer position (transfer nip) between the drum cylinder  62  and the transfer roller  7  by the way of the transfer guide  6 . At this transfer position, the toner image is sequentially transferred from the drum cylinder  62  as the image bearing member to the sheet P as the recording medium. 
     The sheet P onto which the toner image has been transferred is separated from the drum cylinder  62  and fed to the fixing device  9  along the feeding guide  8 . The sheet P passes through the fixing nip portion between the heating roller  9   a  and the pressure roller  9   b  constituting the fixing device  9 . In this fixing nip portion, the unfixed toner image on the sheet P is fixed to the sheet P by being pressed and heated. After that, the sheet P on which the toner image is fixed is fed by the discharge roller pair  10  and discharged to the discharge tray  11 . 
     On the other hand, as shown in  FIG. 2 , after transferring the toner T to the sheet, untransferred residual toner remaining on the drum surface without being transferred onto the sheet adheres on the surface of the drum cylinder  62 . The untransferred residual toner is removed by a cleaning blade  77  which is in contact with the circumferential surface of the drum cylinder  62 . By this, the toner remaining on the drum cylinder  62  is removed, and the cleaned drum cylinder  62  is recharged and then used for the image forming process. The toner (untransferred residual toner) removed from the drum cylinder  62  is stored in a waste toner chamber  71   b  of the cleaning unit  60 . 
     In the above description, the charging roller  66 , the developing roller  32 , and the cleaning blade  77  function as process means acting on the drum cylinder  62 . In the image forming apparatus of this embodiment, a method of removing the untransferred residual toner with the cleaning blade  77  is employed. However, it is also possible to employ a system (cleanerless system) in which the untransferred residual toner having adjusted charge is collected back at the same time as development action by the developing device. In the cleanerless system, an auxiliary charging member (auxiliary charging brush and so on) for adjusting the charge of the untransferred residual toner also functions as the process means. 
     (Structure of Process Cartridge) 
     Referring to  FIGS. 2 and 3 , the detailed structure of the cartridge B will be described. 
       FIG. 3  is an exploded perspective view of the cartridge B. The cartridge B has a frame rotatably supporting the drum cylinder  62  and the developing roller  32 . The frame of cartridge B can be disassembled into multiple units. In the cartridge B of this embodiment, the cleaning unit  60  and the developing unit  20  are integrated, and the frame of the cleaning unit  60  and the frame of the developing unit  20  constitute the cartridge B. 
     In this embodiment, the cleaning unit  60  for holding the drum cylinder  62  and the developing unit  20  for holding the developing roller  32  are connected by the two connecting pins  75 . However, when the cartridge B comprises three or more units into which the cartridge B may be divided. Needless to say, only a part of the units without being coupled by a connecting member such as a pin may be made exchangeable. 
     The cleaning unit  60  includes a cleaning frame  71 , a drum unit U 1 , a charging roller  66 , a cleaning blade  77 , and the like. The cartridge B has a frame which rotatably supports the drum cylinder  62  and the developing roller  32 . 
     The drum unit U 1  comprises a drum cylinder unit U 2 , a coupling member  86  and a pin  88  (see  FIG. 6 ) provided at the drive side end of the drum cylinder unit U 2 . The coupling member  86  is for receiving the rotational force for rotating the drum unit U 1  from the outside of the drum unit U 1 . 
     Further, the drum cylinder unit U 2  has the drum cylinder  62  and a drive side flange  87  as a flange member mounted to the drive side of the drum cylinder  62  (details will be described hereinafter). 
     To the drum cylinder  62 , a rotational force is transmitted from the apparatus main assembly A by way of the driving side flange  87  and the coupling member  86 . 
     As shown in  FIG. 3 , the drum cylinder  62  is rotatable about a rotation axis L 1  (hereinafter referred to as an axis L 1 ). The coupling member  86  is rotatable about a rotation axis L 2  (hereinafter referred to as an axis L 2 ). In this embodiment, the coupling member  86  is connected to the end of the drum cylinder  62  such that the axis L 1  of the drum cylinder  62  and the axis L 2  of the coupling member  86  are substantially coaxial. Therefore, in the following explanation, the axis L 1  and the axis L 2  may be described as the same. 
     Here, the coupling member  86  is structured to be capable of advancing and retracting along the axis L 2  relative to the drum cylinder  62  and to the drive side flange  87 . In other words, the coupling member  86  can move substantially in parallel with the direction (axial direction) in which at least the axis (L 2 ) extends. The coupling member  86  is capable of taking a position (projecting position, advancing position, first position) that is advanced (projecting) toward the outside of the driving side flange  87  and a position (retracted position, second position) retracted toward the inside (toward the drum cylinder) of the driving side flange  87 . In other words, the coupling member  86  can reciprocate along the axial direction between the projecting position and the retracted position. Details will be described hereinafter with reference to Figures parts (b 1 )-(b 4 ) of  FIG. 7 . 
     As shown in  FIGS. 2 and 3 , the developing unit  20  includes a toner accommodating container  22 , a bottom member  21 , a first side member  26 L (non-driving side), a second side member  26 R (driving side), a developing blade  42 , a developing roller  32 , and a magnet roller  34 . Here, the toner accommodating container  22  contains a feeding screw  43  (stirring sheet) as a feeding member for feeding toner, and contains a toner T as a developer. In addition, the developing unit  20  is provided with a compression spring  46  that applies an urging force to regulate the attitude of the unit between the developing unit  20  and the cleaning unit  60 . Furthermore, the cleaning unit  60  and the developing unit  20  are rotatably connected with each other by the connecting pin  75  as a connecting member to constitute the cartridge B. 
     Specifically, rotation holes  23   b L,  23   b R are provided at free ends of the arm portions  23   a L,  23   a R provided at opposite ends of the developing unit  20  with respect to the longitudinal direction (the axial direction of the developing roller  32 ). The rotation holes  23   b L and  23   b R are extended parallel to the axis of the developing roller  32 . 
     In addition, a fitting hole  71   a  for fitting the connecting pin  75  is provided at each of the longitudinal end portions of the cleaning frame  71  which is the frame of the cleaning unit  60 . Then, while aligning the arm portions  23   a L,  23   a R with the predetermined position of the cleaning frame  71 , the connecting pin  75  is inserted into the rotating holes  23   b L,  23   b R and the fitting hole  71   a . By this, the cleaning unit  60  and the developing unit  20  are coupled with each other rotatably around the connecting pin  75  as the connecting member. 
     At this time, the compression spring  46  provided on the base of the arm portions  23   a L,  23   a R abuts to the cleaning frame  71 , so that the developing unit  20  is urged toward the cleaning unit  60  with the connecting pin  75  as the center of rotation. 
     By this, the developing roller  32  as the process means is assuredly urged toward the drum cylinder  62  as a rotatable member. The developing roller  32  is kept at a predetermined distance from the drum cylinder  62  by a spacer (not shown) as a ring-shaped distance maintaining member mounted to the opposite end portions of the developing roller  32 . 
     (Mounting and Dismounting of Process Cartridge) 
     Referring to  FIGS. 4 and 5 , the operation in which the cartridge B is mounted to and dismounted from the apparatus main assembly A in the foregoing structure will be described. 
       FIG. 4  illustrates how the cartridge B is mounted to and dismounted from the apparatus main assembly A. Part (a) of  FIG. 4  is a perspective view as viewed from the non-drive side, and Fig. Part (b) of  FIG. 4  is a perspective view as viewed from the drive side. The driving side is the end portion, in the longitudinal direction of the cartridge B, in which the coupling member  86  is provided. 
     The opening/closing door  13  is rotatably mounted to the main assembly A of the apparatus.  FIG. 4  shows the main assembly A of the apparatus in a state in which the opening/closing door  13  is opened. 
     An opening O 1  is provided in the apparatus main assembly A, and a mounting space for mounting the cartridge B is provided inside the apparatus main assembly A. A drive head (driving shaft, drive transmission member)  14  and a guide member  12  as a guide mechanism are provided inside the main assembly A of the device. 
     Here, the drive head  14  is a main assembly side drive transmission mechanism which is provided in the side of the main assembly A of the apparatus and transmits the driving force to the cartridge B mounted in the apparatus main assembly A, and is engageable with the coupling member  86  of the cartridge B. After the engagement, by rotation of the drive head  14 , the rotational force can be transmitted to the cartridge B. Here, the drive head  14  is supported by the apparatus main assembly A so as to be rotatable about the axis L 4 . In addition, the drive head  14  is provided with a drive pin  14   b  as an imparting portion for applying a rotational force (see  FIG. 7 ). 
     The guide member  12  as a guide mechanism is a main assembly side guide member for guiding the cartridge B into the main assembly A of the apparatus. The guide member  12  may be a plate-shaped member provided with a guide groove. The upper end of the guide member  12  may be contacted to the lower surface of the cartridge B to support the cartridge B from below and to guide (guide) the mounting and dismounting of the cartridge B. 
     Referring to  FIG. 5  and  FIG. 6 , a structure for transmitting the rotational force inputted from the drive head  14  to the cartridge B to the drum cylinder  62  will be described.  FIG. 5  is an illustration of a coupling member  86  as a driving force transmitting part, in which part (a) of  FIG. 5  and part (b) of  FIG. 5  are side views, and part (c) of  FIG. 5  is a perspective view. 
     Part (a) of  FIG. 6  and part (b) of  FIG. 6  are illustrations of the drum gear unit U 2  including the coupling member  86 , part (a) of  FIG. 6  and part (c) of  FIG. 6  are perspective views, and part (cl) of  FIG. 6  is a cross-sectional view taken along a s 1  plane shown in parts (a) and (c) of  FIG. 6 . The coupling member  86  is provided movably in the drum unit U 1 , and part (a) of  FIG. 6  and part (c) of  FIG. 6  show different positions of the coupling member  86  in the drum unit U 1 . 
     As shown in  FIG. 5 , the coupling member  86  includes a supported portion  86   a , a rotational force transmitting portion  86   b , and a coupling portion  86   c . First, the supported portion  86   a  has a cylindrical shape with the rotation axis L 1  of the coupling member  86  as its central axis. Next, the rotational force transmission portion  86   b  includes a cylindrical imparting portion  86   b   1  projecting in a direction perpendicular to the rotation axis L 1 , a large diameter portion  86   b   4  including a cylindrical shape larger in diameter than the supported portion  86   a  and a shaft portion  86   b   3  connecting the large diameter portion  86   b   4  and the coupling portion  86   c . There is a stepped portion  86   b   2  between the large diameter portion  86   b   4  and the supported portion  86   a . The connecting portion  86   c  includes a base portion  86   c   3  having a spherical outer shape, a pair of projecting portions (projection)  86   c   1  projecting from the base portion  86   c   3  outwardly from the rotation axis L 1 , and a recessed portion  86   c   4  of spherical surface concentric with the base portion  86   c   3  formed by hollowing the base portion  86   c   3 . 
     The connecting portion  86   c  is a portion for coupling (coupling) with the drive head  14  provided in the main assembly. The pair of projections  86   c   1  provided on the coupling portion  86   c  abuts the drive pin  14   b  of the drive head  14 , to receive the rotational force (drive force) from the drive head  14 . The contact portion of the projecting portion  86   c   1  in contact with the driving pin  14   b  is a force receiving portion (rotational force receiving portion, driving force receiving portion) for receiving rotational force. The coupling member  86  and the drum cylinder  62  are rotated by the rotational force received by the projecting portion  86   c   1 . 
     The recess  86   c   4  is a surface formed by recessing the base  86   c   3  and faces the side opposite to the supported part  86   a  (that is, the free end side of the coupling member  86 ). The projection  86   c   1  projects from the surface in the neighborhood of the recess  86   c   4 . Specifically, the base portion  86   c   3  has an annular surface (edge) around the recess  86   c   4 , and the projecting portion  86   c   1  projects from the annular edge. The coupling member  86  has a plurality of projections  86   c   1  (two in this embodiment). 
     The projecting portion  86   c   1  projects away from the drum cylinder  62  in the direction of the axis L 1  (axis L 2 ). In other words, the projecting portion  86   c   1  projects toward the tip of the coupling member  86 . The coupling member  86  is remotest away from the drum cylinder  62  in the direction of the axis L 1  at the tip of the projecting portion  86   c   1 . 
     The base portion  86   c   3  forms the end portion (first end portion) of the coupling member  86 . The projecting portion  86   c   1  projects further from the base portion  86   c   3  toward the tip of the coupling member  86 . 
     Further, the supported portion  86   a  and the large-diameter portion  86   b   4  are disposed inside the drum unit and are connected and fixed to a driving-side flange  87  which will be described hereinafter. In other words, the supported portion  86   a  and the large diameter portion  86   b   4  form a fixed end (second end portion) connected to the driving side flange  87 . 
     The shaft portion  86   b   3  is a connecting portion connecting the first end portion and the second end portion of the coupling member. The distance from the axis L 2  of the coupling member  86  to the surface of the shaft portion  86   b  (that is, the radius of the shaft portion  86   b ) is shorter than the distance from the projecting portion  86   c   1  to the axis. The distance between the projecting portion  86   c   1  and the axis L 2  differs depending on the position of the projecting portion  86   c   1  but both the shortest distance and the longest distance from the projecting portion  86   c  to the axis L 2  are longer than the distance from the axis L 2  to the surface of the shaft portion  86   b.    
     The two projecting portions  86   c   1  are inclined at an angle θ 1  and an angle θ 2  relative to the rotation axis L 1 . And, angles θ 1  and  02  are substantially equal. 
     That is, the pair of projections  86   c   1  has a conical shape with the rotation axis L 1  as the central axis and has a line inclined from the rotation axis L 1  by the angle θ 1  as a generating line. In other words, the projecting portion  86   c   1  of the coupling portion  86   c  has such a shape that a distance from the rotation axis L 2  increases toward the tip of the coupling member  86  (the tip of the projecting portion  86   c   1 ) (that is, as being away from the drum cylinder  62 ). 
     The projection (projection)  86   c   1  has an inner surface facing the axis L 2  and an outer surface facing away from the axis L 2 . Both the inner surface and the outer surface of the projection  86   c   1  are structured to increase the distance from the axis L 2  toward the tip of the projecting portion  86   c   1 . 
     In other words, the projecting portion (projection)  86   c   1  has an outer surface that is more distant from the axis L 2  as it is away from the drum cylinder  62  in the direction of the axis L 2  (axis L 1 ). The projecting portion (projection)  86   c   1  has an inner surface which increases the distance from the axis L 2  as it is away from the drum cylinder  62  along the direction of the axis L 2  (axis L 1 ). The inner and outer surfaces of the projecting portion  86   c   1  have maxim distances from the axis L 2  at the tip of the projecting portion. 
     Referring to  FIG. 6 , the drum gear unit U 2  in which the coupling member  86  is incorporated will be described. As shown in  FIG. 6 , the drum gear unit U 2  comprises the coupling member  86 , the drive side flange  87 , a lid member  88 , and a compression spring  89 . 
     The driving side flange  87  is a flange (drum flange) fixed to an end portion on the drive side of the drum cylinder  62 , and has a gear on the outer circumference thereof. Therefore, sometimes the drive side flange  87  is called a drum gear. The gear on the drive side flange  87  engages with the gear provided at the end of the developing roller  32  ( FIG. 32 ), so that when the drum cylinder  62  rotates, the driving force is transmitted to the developing roller  32 . 
     The coupling member  86  is provided so that at least the rotational force transmitting portion  86   b   1  is accommodated in the hollow portion  87   a  of the driving side flange (drum gear)  87 , and at least a part of the coupling portion  86   c  is projected outwardly beyond a driving side flange  87 . The lid member  88  is fixed to the driving side flange  87  by adhering the bonding surface  88   d  to the surface  87   c  of the driving side flange  87 , and the supporting portion  88   a  supports the supported portion  86   a  of the coupling member  86  so as to be movable in the direction of the rotation axis L 1 . 
     By this, the coupling member  86  can move in the direction of the rotation axis L 1  (the direction of the arrow X 4  and the direction of the arrow X 5 ) in the drum gear unit U 2 . Here, the coupling member  86  is prevented from disengaging in the direction of the arrow X 5  by the abutment of the stepped portion  86   b   2  and the free end portion  88   c  of the support portion  88   a , and the coupling member  86  is prevented from disengaging in the direction of the arrow X 4  by the abutment between the rotational force transmitting portion  86   b   1  and the retaining portion  87   b  of the drive side flange  87 . A compression spring  89  is provided between the rotational force transmission portion  86   b   1  of the coupling member  86  and the spring receiving portion  88   b  of the lid member  88 . By this, the coupling member  86  is urged in the direction (the arrow X 4  direction) in which the coupling portion  86   c  projects from the driving side flange  87 . 
     When the rotational force is transmitted to the coupling member  86 , the rotational force transmission portion  86   b   1  comes into contact with the rotational force receiving portion  87   d   1  of the drive-side flange  87  to transmit the rotational force to the drive-side flange  87 . Press-fit portion  87   e  of the drive side flange  87  is press-fitted and fixed to the inner diameter portion of the drum cylinder  62  (see  FIG. 3 ). With this structure described above, the rotational force is transmitted from the drive head  14  to the drum cylinder  62 . The coupling member  86  is connected to the end of the drum cylinder  62  by the way of the driving side flange  87 , and the coupling member  86  and the drum cylinder  62  are interlocked with each other. The way of connecting the coupling member and drum cylinder  62  is merely an example. It will suffice if the drum cylinder  62  can be rotated by the rotation of the coupling member  86 . 
     Then, referring to  FIG. 7 , the operation of the coupling member  86  when the cartridge B is dismounted from the apparatus main assembly A will be described.  FIG. 7  is an illustration of the dismounting operation of the drum unit U 2 , in which the main assembly A is shown only by the drive head  14  and the coupling guide (guide member  15 ). The drum gear unit U 2  of the cartridge B sequentially escapes from  FIG. 7  (a 1 ) to (a 4 ), and  FIG. 7  (a 1 ) shows the state in which driving of the apparatus main assembly A is completed. Part (b 1 ) of  FIG. 7  to part (b 4 ) thereof are cross-sectional views (S 2  cross-sectional view) of the structures shown in part (a 1 ) of  FIG. 7  to part (a 4 ) thereof, taken along the line S 2 -S 2 . For the sake of illustration, the drive head  14  is shown without cross-section. 
     The guide member  15  is provided in the neighborhood of the drive head  14  to guide the coupling member. The guide member  15  is disposed behind the drive head  14  when viewing the interior of the apparatus main assembly A through the opening O 1  (see  FIG. 4 ) of the apparatus main assembly A. 
     As shown in part (a 1 ) of  FIG. 7  and part (b 1 ) of  FIG. 7 , when the coupling member  86  is positioned in the projecting position, the coupling member  86  is engaged (coupled) with the drive head  14 . When the cartridge B is moved in the direction of the arrow X 3  after the completion of the rotation of the drive head  14 , the coupling member  86  moves in the direction of the arrow X 3  together with the drum gear unit U 2 . At the same time, the upstream side of the coupling member  86  in the dismounting direction of the cartridge B is brought into contact with the drive head  14 . In other words, the inner surface of the recess  86   c   4  or the projection  86   c   1  is brought into contact with the drive head  14 . This causes the coupling member  86  to move in the direction of the arrow X 5  (see part (a 2 ) of  FIG. 7  and part (b 2 ) thereof). 
     In this embodiment, both the contact portions of the drive head  14  and the coupling member  86  are inclined relative to the axis L 1  and the axis L 4  (see parts (b 1 ) to (b 4 ) of  FIG. 7 ). that is, the free end of the driving head  14  is inclined relative to the axis L 4  of the driving head  14 . In addition, the surfaces of the recess  86   c   4  of the coupling member and the projecting portion  86   c   1  are also inclined relative to the axis L 1  (axis L 2 ). 
     Therefore, when the cartridge B is moved in the X 3  direction with the drive head  14  and the coupling member  86  in contact, the force F 1  received by the coupling head  86  from the drive head  14  has the component in the direction of the arrow X 5  (component in the axial direction). By this, the coupling member  86  is retracted in the direction of the arrow X 5  (toward the drum cylinder) by the force F 1  received from the contact portion to the drive head  14 . 
     However, it will suffice if at least one of the contact portion between the driving head  14  and the inner surface of the coupling member  86  and the driving head  14  is inclined relative to the axis L 2  of the coupling member  86 . In this case, the force F 1  received by the coupling member  86  has a component for moving the coupling member  86  in the direction of the arrow X 5 . 
     In this embodiment, the inner surface of the projecting portion  86   c   1  facing the axis L 2  is structured such that the distance from the axis L 2  increases as the entirety thereof moves away from the drum cylinder  62  in the direction of the axis L 1 . However, it is unnecessary for the entire projecting portion  86   c   1  to have such a structure. At least a part of the inner surface of the projecting portion  86   c   1 , that is, it will suffice if at least a portion that is in contact with the driving head  14  has the above-mentioned inclination. If so, when the inner surface of the projecting portion  86   c   1  comes into contact with the driving head  14 , the coupling member  86  is easily retracted toward the drum cylinder along the direction of the axis L 2 . 
     When the cartridge B is further moved in the direction of the arrow X 3  from the state shown in part (a 2 ) of  FIG. 7  and part (b 2 ) thereof, the coupling member  86  further moves in the direction of the arrow X 5 . The coupling member  86  finally becomes in the state shown in part (a 4 ) of  FIG. 7 , part (b 4 ) thereof through the state shown in part (a 3 ) of  FIG. 7 , part (b 3 ) thereof. At this time, the free end portion  86   c   12  of the projecting portion  86   c   1  does not overlap the driving head  14  in the direction of the rotation axis L 1 . By this, the coupling member  86  can circumvent the drive head  14 , and the cartridge B can be pulled out of the apparatus main assembly A. 
     In this embodiment, the coupling member  86  is structured to move substantially in parallel with the axis L 1  of the drum cylinder  62 . The coupling member  86  moves along the axis L 2  while keeping the axis L 2  of the coupling member  86  coaxial with the axis L 1  of the drum cylinder  62  (that is, keeping the state in which the axis L 1  and the axis L 2  overlap with each other). 
     However, the coupling member  86  may move in a direction inclined relative to the axis L 1 , that is, the axis L 2  may not overlap with the axis L 1 . For example, if the coupling member  86  moves along the axis L 2 , the movement direction thereof may not necessarily be parallel to the axis L 1 . In this case, the angle of the axis L 2  relative to the axis L 1  is substantially constant before and after the coupling member  86  moves along the axis L 2 . 
     In this embodiment, the coupling member  86  moves along the axis L 2  while maintaining the state in which the angle of the axis L 2  relative to the axis L 1  is substantially 0 degree. 
     As described above, the projecting portion  86   c   1  is formed such that the distance from the axial line L 2  is increased as the distance from the drum cylinder  62  increases in the direction of the axis L 1 . In other words, the distance from the axis L 2  becomes larger toward the tip of the projecting portion  86   c   1 , that is, the projecting portion  86   c   1  expands in the radial direction of the coupling member  86  toward the there is provided thereof. 
     Therefore, as shown in  FIG. 7  (b), the projecting portion  86   c   1  has a small diameter on the rear end side (root side), so that in the state that the coupling portion  86   c  is in contact with the drive head  14 , a large distance can be assured between the outer surface of the projecting portion  86   c   1  and the guide portion  15   a  of the member  15 . By this, the coupling member  86  can move without the joint portion  86   c  contacting to the driving head  14  and to the guide member  15  at the same time. That is, when the coupling member  86  moves in the direction of the arrow X 5 , the movement of the coupling member  86  is not hindered by the guide member  15 . In other words, the engagement between the coupling member  86  and the drive head  14  can be smoothly released, and the load applied to the user when extracting the cartridge B out of the apparatus main assembly A can be reduced. 
     Here, the guide portion  15   a  is an inclined portion inclined relative the axis L 4  of the drive head  14  and is inclined in the direction of the facing the drive head  14   g . Since the guide portion  15   a  is inclined relative to the axis L 4 , the guide member  15  protrudes so as to approach the axis L 4 , and the projecting portion faces the shaft portion  86   b   3  (see  FIG. 5 ) of the coupling member  86 . As shown in  FIG. 5 , the shaft portion  86   b   3  of the coupling member  86  has a smaller diameter than the projecting portion  86   c   1  and the base portion  86   c   3 , so that it can be avoided that the protruding portion of the guide member  15  contacts the coupling member  86 . 
     As described above, according to this embodiment, the projecting portion  86   c   1  expands radially outward as it goes away from the drum flange  62  in the direction of the axis L 1  (that is, as it goes toward the tip (free end) of the coupling member  86 ). Therefore, even though the guide member  15  is provided in the main assembly of the apparatus, the coupling member  86  can be retracted smoothly from the drive head  14  when taking the cartridge B out of the apparatus main assembly A. 
     It is not necessary that the whole of the projecting portion  86   c   1  has the above-mentioned shape, and it will suffice if the portion necessary for passing through the gap between the guide member  15  and the driving head  14  has the above-mentioned shape. 
     That is, at least a part of the projecting portion  86   c   1  may be structured to increase the distance from the axis L 2  as the distance from the drum flange  62  increases in the direction of the axis L 1 . 
     In this embodiment, the coupling member  86  is formed so as not to contact the guide member  15  when the coupling member  86  is retracted while being in contact with the drive head  14 . However, even if the coupling member  86  is upsized, it is also possible to employ a structure in which it simultaneously comes into contact with the drive head  14  and the guide member  15  when the coupling member  86  retracts. For example, even if the coupling member  86  contacts with the drive head  14  and with the guide member  15  at the same time, if the guide member  15  is elastically deformed, for example, the load at the time when the coupling member  86  is retracted in the direction of the arrow X 5  is not so large. The inner surface of the projecting portion  86   c   1  is inclined so as to be along the tip of the driving head  14  and the outer surface of the projecting portion  86   c   1  is inclined along the guide member  15 . Therefore, the coupling member  86  can be moved to the retracted position, while the outer surface of the projecting portion  86   c   1  is guided by the guide member  15  and the inner surface of the projecting portion  86   c   1  is guided by the driving head  14 . The coupling member  86  can smoothly disengage from the drive head  14 . 
     In other words, if the load on the user at the time when dismounting the cartridge B is within the allowable range, the wall thickness of the coupling portion  86   c  may be increased and the coupling member  86  may be contacting with the guide member  15  when the coupling member  86  is retracted. Increasing the wall thickness of the coupling portion  86   c  can improve the strength of the coupling portion  86   c , so that the rotation accuracy of the drum cylinder  62  can be improved. 
     In this embodiment, the projecting portion  86   c   1  projects from the base portion  86   c   3  provided in the coupling portion  86   c , but, as shown in parts (a)-(c) of  FIG. 8 , a pair of projecting portions  186   c   1  may be projected from the shaft portion  186   b   3 . 
     In this case, the projecting portion  186   c   1  which is a rotational force receiving portion (driving force receiving portion) has a shape expanding outward in the radial direction of the coupling member  186  as going toward the tip thereof. 
     Referring to  FIG. 24 , the operation of the coupling member  86  when mounting the cartridge B in this embodiment will be described. Part (a) of  FIG. 24 , part (b) of  FIG. 24  and part (c) of  FIG. 24  illustrate the coupling member  86 . Part (d) of  FIG. 24 , part (e) thereof, and part (f) thereof are cross-sectional views of the coupling member  86 . 
     Part (d) of  FIG. 24 , part (e) thereof, and part (f) thereof are cross-sectional views corresponding to part (a) of  FIG. 24 , part (b) thereof and part (c) thereof, respectively. 
     In this embodiment, if the coupling member  86  (drum cylinder  62 ) is not at a predetermined phase, the cartridge B cannot be mounted in the apparatus main assembly A or it is difficult to mount it. In other words, if the coupling member  86  has the phase shown in part (a) of  FIG. 24  and part (d) of  FIG. 24 , the outer surface of the projecting portion  86   c   1  (coupling portion  86   c ) of the coupling member  86  collides against the driving head  14  of the apparatus main assembly A. In such a case, the cartridge B cannot be mounted, or it is difficult to mount. 
     On the other hand, in the case of the phases shown in part (b) of  FIG. 24  and part (e) of  FIG. 24  when the cartridge B is mounted, the projecting portion  86   c   1  of the coupling member  86  does not contact the driving head  14 . On the other hand, the base portion  86   c   3  of the coupling member  86  contacts the drive head  14 . However, when the base portion  86   c   3  comes into contact with the inclined portion (curved surface portion) provided at the tip of the drive head  14 , the coupling member  86  retracts in the axial direction. Therefore, mounting of cartridge B is not hindered. Finally, the state shown in part (c) of  FIG. 24  and part (f) of  FIG. 24  is established, and the axis of the coupling member  86  and the axis of the drive head  14  become substantially coaxial with each other. The coupling member  86  is engageable with the drive head  14  and becomes capable of receiving the driving force (rotational force) from the drive head  14 . 
     On the other hand, in the state shown in part (a) of  FIG. 24  and part (d) of  FIG. 24 , the user may not be able to mount the cartridge B in the apparatus main assembly A in some cases. In such a case, it is necessary to take the cartridge B out of the apparatus main assembly A and rotate the coupling member  86  until the state shown in  FIG. 24  (b) and part (d) thereof is reached. Therefore, it is desirable to shorten the width of the projecting portion  86   c   1  so that the projecting portion  86   c   1  does not collide against the driving head  14  when mounting the cartridge B in as many cases as possible. 
     On the circumference of the base portion  86   c , a region  86   c   11  where the projecting portion  86   c   1  exists is longer than a region where the projecting portion  86   c   1  does not exist provided. In other words, the sum of the widths of the two projecting portions  86   c   1  is less than half of the circumferential length of the base portion  86   c.    
     As shown in part (a) of  FIG. 25  and part (b) of  FIG. 25 , an inclined portion  86   c   5  may be provided at the tip of the base portion  86   c   3  so that the coupling member  86  is easily retracted when it comes into contact with the drive head  14 . 
     The inclined portion  86   c   5  is inclined relative to the axis of the coupling member  86 . Therefore, when the inclined portion  86   c   5  contacts with the drive head  14 , the coupling member  86  receives a force in the axial direction. This force is effective to retract the coupling member  86  in the axial direction. 
     If at least one of the contact portions of the coupling member  86  and the drive head  14  is inclined relative to the axis of the coupling member  86 , the coupling member  86  can retract in the axial direction by receiving the force in the axial direction. 
     Embodiment 2 
     Embodiment 2 of the present invention will be described referring to  FIGS. 9 to 13 . 
     In the description of this embodiment, the same reference numerals as in Embodiment 1 are assigned to the elements having the corresponding functions in this embodiment, and the detailed description thereof is omitted. 
     Referring first to  FIG. 9 , the structure of the drum gear unit U 23  will be described  FIG. 9  is an illustration of the structure of the drum gear unit U 23 , which is an exploded perspective view shown in the order of assembling from part (a) of  FIG. 9  to (e). 
     Part (a) of  FIG. 9  and part (b) of  FIG. 9  are exploded views of the first unit U 21 . The first unit U 21  comprises a coupling member  286 , a translating cam  288 , and a rotating cam  289 . A supported portion  286   a  of the coupling member  286  is assembled so as to penetrate the hole portion  288   a  of a translating cam  288  and a hollow portion  289   a  of the rotating cam  289 . 
     On the coupling member  286 , a pressed portion  286   b  is provided between a shaft portion  286   a  and a coupling portion  286   c . The translating cam  288  includes a cylindrical surface  288   b , a projecting portion  288   c  projecting radially outward from the cylindrical surface  288   b , a cut-away portion  288   d  provided by cutting a part of the cylindrical surface  288   b  away, and a pressing portion  288   e.    
     The rotating cam  289  has a hollow portion  289   a , a cut-away portion  289   c , an outer shape portion  289   b , and a projecting portion  289   d . The hollow portion  289   a  accommodates the translating cam  288  and the coupling member  286  and rotatably supports the cylindrical surface  288   b.    
     In addition, the cut-away portion  289   c  is formed so as to cut out a part of the hollow portion  289   a , and accommodates the projecting portion  288   c . Here, the cut-away portion  289   c  is provided with a slanted surface portion  289   c   1 , and the projecting portion  288   c  opposed thereto is also provided with a slanted surface portion  288   c   1 . 
       FIG. 9  (c) is an exploded view of a second unit U 22 . The second unit U 22  comprises a first unit U 21 , an auxiliary member  290 , and a pin  291 . The coupling member  286  of the first unit U 21  is assembled so that the shaft portion  286   a  penetrates a hole  290   a  of the auxiliary member  290 . Thereafter, the pin  291  is inserted so as to penetrate a lateral hole portion  290   b  of the auxiliary member  290  and a hole portion  286   d  of the coupling member  286 . 
       FIG. 9  (d) is an exploded view of the drum gear unit U 23 . The drum gear unit U 23  comprises the second unit U 22 , a driving side flange (drum gear  287 ), a compression spring  292 , and a cover member  294 . The drum gear  287  accommodates the second unit U 22  in an inside  287   a , the shaft portion  286   a  of the coupling member  287  penetrates a hole (not shown) of the drum gear  287  and projects out toward the cover member  294  (in the direction of the arrow X 5 ). Here, the second unit U 22  is inserted so that the pin  291  is in transmitted portion  287   b  of the hollow portion  287 . The shaft portion  286   a  further penetrates an inner diameter portion  292   a  of the compression spring  292 , and the cover member  294  is fixed to the free end. The compression spring  294  abuts a spring abutment portion  294   b  of the cover member  294  and a spring abutment portion (not shown) of the drum gear  287 . 
     As shown in  FIG. 9  (e), the drum gear unit U 23  assembled in such a manner that the projecting portion  289   d  of the rotating cam  289  projects from the drum gear  287  in the arrow X 4  direction. In this state, the compression spring  292  is compressed and urges the coupling member  286  together with the cover member  294  move in the direction of the arrow X 5  with respect to the drum gear  287 . 
     The rotational force transmitted to the coupling member  286  is transmitted to the driving side flange (the drum gear  287 ) by way of the pin  291  and the transmitted portion  287   b  of the drum gear  287 . 
     Referring to  FIG. 10 , the structure of the cleaning unit  61  will be described. The drum gear unit U 23  is fixed to one end of the drum cylinder  62 . The drum gear unit U 23  and drum cylinder  62  constitute drum unit U 12 . The drum unit U 12  is disposed in a cleaning frame  71  and is rotatably supported in the cleaning unit  61  by a bearing  293 . The supporting portion  293   a  of the bearing  293  rotatably supports the outer shape portion  289   b  of the rotating cam  289 . In addition, a stopper  293   b  is assembled so as to enter the cut-away portion  288   d  of the translating cam  288 . By this, the rotation cam  289  is rotatable relative to the bearing  293 , and the translation cam  288  is non-rotatable relative to the bearing  293 . 
     Referring to  FIG. 11 , the structure of a developing unit  21  and a cartridge B will be described. The developing unit  21  is connected to the cleaning unit  61  as in the Embodiment 1. In addition to this, a lever member  297  is further connected to the developing unit  21  and the cleaning unit  61 . 
     The lever member  297  is provided on a second side member  226 R of the cartridge B and extends in a direction away from the drum cylinder toward the tip of the lever member  297 . In other words, the tip of the lever member  297  projects away from the second side member  226 R. 
     The second side member  226 R is a part of the frame of the cartridge B and forms the side surface of the cartridge B. That is, the second side member  226 R is provided at the end of the cartridge B in the direction of the axis L 1  of the drum cylinder  62 . 
     The lever member  297  is provided with a projection  297   a , an elongated hole portion  297   b , and a bent portion  297   c . The elongated hole portion  297   b  is connected with the second side member  226 R by the fixing member  295 , and is held so as to be movable along the long axis direction of the long round hole relative to the second side member  226 R, and rotatable about fixed the member  295 . A lever spring (compression spring) is provided between the spring abutment portion  297   c   1  of the bent portion  297   c  and the second side member  226 R to urge the lever member  297  in the direction of the arrow X 3 . A pressed portion  297   c   2  of the bent portion  297   c  is a portion to be pushed by the cartridge pushing portion (not shown) of the opening/closing door  13  when the cartridge B is mounted to the apparatus main assembly A and the opening/closing door  13  of the apparatus main assembly A is closed. The projection  297   a  is inserted into a hole  289   d   1  formed in the projection  289   d  of the rotating cam  289 . 
     Referring to  FIG. 12 , the operation of the lever member  297  and the drum gear unit U 23  will be described. Part (a) of  FIG. 12  and part (b) of  FIG. 12  are illustrations of the operation of the lever member  297 , and part (c) and (d) thereof is an illustration of the operation of the drum gear unit U 23 . 
     The lever member  297  and the coupling member  286  are structured so as to move in interrelation with the opening and closing operation of the opening/closing door  13  (see  FIG. 4 ).  FIG. 12  (a) shows a state in which the cartridge B is mounted in the apparatus main assembly and the opening/closing door  13  is opened. When the opening/closing door  13  is closed from this state, as shown in  FIG. 12  (b), the pressed portion  297   c  of the lever member  297  is pushed in the direction of the arrow X 6  by a cartridge pushing portion (not shown) of the opening/closing door  13 . Then, the lever member  297  moves in the right direction in  FIG. 12  (b) along the long axis direction of the elongated hole portion  297   b . As the lever member  297  moves, the projection  297   a  rotates the rotating cam  289  in the direction of the arrow R 3  by way of the hole  289   d   1  of the rotating cam  289 . 
     That is, when the rotating cam  289  rotates from the state shown in  FIG. 12  (c), the state shown in  FIG. 12  (d) is established. When the rotating cam  289  rotates by the movement of the lever member  297 , the slope portion  289   c   1  comes into contact with the projecting portion  288   c  of the translating cam  288  as shown in  FIG. 12  (d). At this time, since the translating cam  288  cannot rotate relative to the bearing  293  as described above, in order to avoid interference with the slope portion  289   c   1 , the projection  288   c  ascends the slope portion  289   c   1  to move in the direction of the arrow X 4  (outward in the axial direction). 
     The translation cam  288  pushes the coupling member  286  when moving in the direction of the arrow X 4 . Therefore, the coupling member  288  also moves in the direction of the arrow X 4 . More specifically, the pressing portion  288   e  of the translating cam  288  pushes the pressed portion  286   b  of the coupling member  286  to apply a force in the direction of the arrow X 4 , so that the coupling member  286  moves in the direction of the arrow X 4 . 
     That is, when the opening/closing door  13  (see  FIG. 4 ) is closed, the coupling member  286  advances in a direction approaching the drive head  14 . By this, the coupling portion (driving force receiving portion)  286   c  provided on the coupling member  286  is enabled to engage with the drive head  14 . In other words, the coupling portion  286   c  becomes in a state capable of receiving the rotational force (driving force) from the drive head  14 . 
     The lever member  297  is an operation member operated by the opening/closing door  13 . 
     Referring to parts (a 1 ) to (a 4 ) of  FIG. 13  and parts (b 1 ) to (b 4 ) of  FIG. 13 , the movement of the drum gear unit U 23  (coupling member  286 ) will be explained. Figures show the process of mounting the cartridge B in the main assembly A and the process of closing the door  13  after mounting the cartridge B. 
     In  FIG. 13 , for the apparatus main assembly A, only the drive head  14  and the guide member  15  are shown. 
     In the process of mounting the cartridge B in the apparatus main assembly A, the coupling member  286  moves in the right direction (the direction of the arrow X 2 ) in part (a 1 ) of  FIG. 13  and part (b 1 ) of  FIG. 13 . At this time, the tip  286   c   12  of the coupling member  286  is located approximately at the same position as the tip of the drive head  14 . 
     As shown in part (a 2 ) of  FIG. 13  and part (b 2 ) of  FIG. 13 , on the way of mounting the cartridge B, the downstream side of the coupling member  286  in the mounting direction contacts the guide member  15 . More specifically, the projecting portion  286   c   1  of the coupling member  286  contacts the guide portion  15   a  of the guide member  15 . In this state, the cartridge B is further inserted into the apparatus main assembly A, by which the coupling member  286  moves in the right direction. Then, the projecting portion  286   c   1  receives a force from the guide portion  15   a , so that the coupling member  286  moves in the direction of the arrow X 4  in  FIG. 13  (b 2 ), into the state shown in part (a 3 ) of  FIG. 13 , part (b 3 ) thereof. 
     That is, the projecting portion  286   c   1  and the guide portion  15   a  are inclined with respect to the axis L 1  of the coupling member  286 . Therefore, when the projecting portion  286   c   1  and the guide portion  15   a  come into contact, the force received by the projecting portion  286   c   1  from the guide portion  15   a  has a component in the direction along the axis L 1 . In other words, the force received by the projecting portion  286   c   1  from the guide portion  15   a  has an upward component in  FIG. 13  (b 2 ). By this force, the coupling member  286  moves upward in  FIG. 13  (b 2 ) with the mounting operation of the cartridge B into the state of  FIG. 13  (a 3 ), part (b 3 ) thereof. Part (a 3 ) of  FIG. 13  and part (b 3 ) thereof show a state where the cartridge B is completely loaded in the apparatus main assembly A, but the opening and closing door  13  (see  FIG. 4 ) is still open. At this time, the axis L 2  of the coupling member  286 , the axis L 1  of the drum cylinder, and the axis L 4  of the drive head  14  are substantially coaxial with each other. 
     When the opening/closing door  13  is closed from the state shown in part (a 3 ) of  FIG. 13  and part (b 3 ) thereof, the rotating cam  289  rotates in the clockwise direction (arrow R 3  direction) in  FIG. 13  (a 4 ) by the mechanism described above. By this, the coupling member  286  further advances toward the drive head  14 . By this, the coupling member  286  is brought into a state of capable of engaging with the drive head  14  to receive the driving force from the drive head  14 . In other words, when the drive head  14  rotates in this state, the drive pin  14   b  provided on the drive head  14  engages with the projection  286   c   1  of the coupling member  286  so that the drive is transmitted from the drive pin  14   b  to the coupling member  286 . The contact portion of the projecting portion  286   c   1  in contact with the driving pin  14   b  is the rotational force receiving portion (force receiving portion, driving force receiving portion) which receives the rotational force from the driving pin  14   b.    
     In this embodiment, the coupling member  286  is moved stepwise from the retracted position (second position) to the projecting position (first position) in the process until the cartridge B is mounted to the apparatus main assembly A and the opening/closing door  13  is closed. As the cartridge B moves to the inside of the apparatus main assembly A, the outer surface of the projecting portion  286   c   1  is guided by the guide portion  15   a , so that the coupling member  286  slightly approaches the projecting position from the retracted position (parts (a 3 ), (b 3 ) of  FIG. 13 ). thereafter, when the opening/closing door  13  is closed, the coupling member  286  completely moves to the projecting position in interrelation with the movement of the lever member  297 , so that the coupling member  286  can be coupled with the driving head  14  (parts (a 4 ) and (b 4 ) of  FIG. 13 ). 
     However, in the course of movement of the cartridge B to the inside of the apparatus main assembly A, the outer surface of the projecting portion  286   c   1  does not necessarily need to contact the guide portion  15   a , and the coupling member  286  does not need to move in the direction of the axis L 2 . Another structure is possible in which at the time when the cartridge B is inserted into the main assembly A of the apparatus, the coupling member  286  does not contact the guide portion  15   a  and remains in the state of the retracted position. Even in such a case, the coupling member  286  is moved from the retracted position to the projecting position by the closing operation of the opening/closing door  13 . 
     On the contrary to the case where the cartridge B is dismounted from the apparatus main assembly A, when dismounting the cartridge B from the apparatus main assembly A, the cartridge B performs the operation in reverse order of the above-described process. First, when the opening and closing door  13  is opened, the force in the X 6  direction (see  FIG. 12  (b)) to the lever member  297  becomes not applied, and the lever member  297  is moved in the direction of the arrow X 3  ( FIG. 11 ) by the urging force of the spring  296 . Then, the rotating cam  289   d  rotates in the direction of the arrow R 9  in  FIG. 13  (a 4 ), and the urging force of the compression spring  292  moves the coupling member  286  in the direction of the arrow X 5  (part (a 3 ) of  FIG. 13 , part (b 3 ) thereof). As the cartridge B is further pulled out, the coupling member  286  further moves in the direction of the arrow X 5  by the urging force of the compression spring  292  (part (a 2 ) of  FIG. 13  and part (b 2 ) thereof), and finally, the state shown in parts (a 1 ) and (b 1 ) of  FIG. 13  is established. By this, the cartridge B can be removed from the main assembly A of the apparatus. 
     When dismounting the cartridge B from the apparatus main assembly A, the upstream side of the coupling member  286  in the dismounting direction contacts with the guide portion  15   a.    
     Also in this embodiment, as in the Embodiment 1, at least a part of the outer surface of the projecting portion  286   c   1  of the coupling member  286  is inclined relative to the axis L 2 . 
     The outer surface of the projecting portion  286   c   1  has such a shape that it expands in the radial direction of the coupling member  286  (increases the distance to the axis L 2 ) as it goes toward the tip (free end) thereof. In other words, the rear end of the projecting portion  286   c   1  has a smaller diameter than the tip. Therefore, it is possible to assure a wide distance between the guide portion  15  and the coupling member  286  in the process of mounting and dismounting the cartridge B to and from the apparatus main assembly A (see part (b 2 ) of  FIG. 13  and part (b 3 ) thereof). The projecting portion  286   c   1  of the coupling member  286  avoids interference with the guide member  15 . Therefore, the coupling member  286  can smoothly perform the coupling and decoupling relative to the drive head  14 . 
     That is, even when the outer surface of the projecting portion  286   c   1  comes into contact with the guide portion  15  at the time of mounting or dismounting the cartridge B, the projecting portion  286   c   1  is not prevented from moving by the guide portion  15  and is smoothly guided by the guide portion  15 . This makes it easy to mount and dismount cartridge B. 
     The outer surface of the projecting portion  286   c   1  faces away from the axis L 2  of the coupling member  286 . In this embodiment, the distance from the axis L 2  of the entire outer surface of the outer surface increases as it moves away from the drum cylinder  62  in the direction of the axis L 1 . In other words, the outer surface of the projecting portion  286   c   1  has the largest distance from the axis L 2  at the tip of the projecting portion  286   c.    
     However, it is not necessary that the entire outer surface of the projecting portion  286   c   1  has such a shape, but it will suffice if the portion necessary for the projecting portion  286   c  to pass through between the driving head  14  and the guide member  15  has the above-described shape. If will suffice if at least a part of the outer surface of the projecting portion  286   c   1 , that is, at least a portion facing the guide portion  15  is structured so as to increase the distance from the axis L 2  as moving away from the drum cylinder  62  in the direction of the axis L 1 . 
     Embodiment 3 
     Another embodiment will be described below referring to  FIGS. 14 to 19 . In this embodiment, the coupling member  386  advances and retracts along the axial direction by the rotation of the operating member (the lever  394 ). 
     Referring to  FIG. 14 , the structure of the drum gear unit U 31  in this embodiment will be described. 
     Part (a) of  FIG. 14  is an exploded perspective view of the structure of a drum gear unit U 31 ,  FIG. 14  (b) is a perspective view, part (c) of  FIG. 14  and part (d) of  FIG. 14  are sectional views taken along S 4  plane and the S 5  plane, respectively. 
     As shown in part (a) of  FIG. 14  and part (c) of  FIG. 14 , the drum gear unit U 31  comprises a driving side flange (drum gear  387 ), a coupling member  386 , a cam  388 , a lid member  389 , a compression spring  390 , and a pin  391 . The coupling member  386  is assembled so that a shaft portion  386   a  penetrates a hole portion  388   a  of the cam  388 , and then a pin  391  is inserted and fixed in a hole portion  386   d  of the coupling member  386 . These parts are provided inside an inner cylindrical surface  387  an of the drum gear  387 , and thereafter the lid member  389  is fixed to the drum gear  387  with the compression spring  390  interposed therebetween. At this time, the compression spring  390  is sandwiched between the pin  391  and the lid member  389  in a compressed state as shown in  FIG. 14  (d), and the pin  391  and the cam  388  are pushed outwardly (the direction of the arrow X 4 ) of the drum gear  387 . By this, as shown in  FIG. 14  (b), a part of the slanted portion  388   e  of the cam  388  projects from the drum gear  387 . The shaft portion  386   a  of the coupling member  386  is fitted and supported in the hole portion  388   a  of the cam  388 , and the outer peripheral portion  388   c  of the cam  388  is fitted and supported to the inner cylindrical surface  387   a  of the drum gear  387 . By this, the coupling member  386  is supported such that the rotational axis thereof and the rotational axis of the drum gear  387  are substantially parallel with each other. Furthermore, by assembling the pin  391  to enter the groove  387   b  of the drum gear  387 , the rotational force of the coupling member  386  can be transmitted to the drum gear  387  by the way of the pin  391 . Here, the cam  388  is merely in a fitting relationship with the coupling member  386  and the drum gear  387 , 8nd therefore, they do not rotate integrally. 
     Referring to  FIG. 15 , the structure of the cleaning unit  61  in this embodiment will be described.  FIG. 15  is a perspective view illustrating the structure of the cleaning unit  61 . 
     As shown in  FIG. 15 , the drum gear unit U 31  is integrally fixed to a drum cylinder  62  in the same manner as in the previous embodiment, and then assembled into the cleaning frame  71  using a bearing  393 . The bearing  393  is provided with an abutting surface  393   b  on the upper side of the hole  393   a  through which the coupling member  386  penetrates, and is provided with a cut-away portion  393   c  on the side where the developing unit  21  (see  FIG. 16 ) will be assembled later. The drum gear unit U 31  is assembled with the cleaning frame  71  and the bearing  393  so that the abutted surface  388   d  of the cam  388  opposes the contact surface  393   b  of the bearing  393 . 
     Referring to  FIG. 16 , a structure in which the cartridge B is assembled by combining the cleaning unit  61  and the developing unit  21  will be described.  FIG. 16  (a) is an exploded perspective view of the cartridge B, and  FIG. 16  (b) is a perspective view of the cartridge B, in which only the driving side is shown. Part (c) of  FIG. 16  and part (d) of  FIG. 16  are detailed views of the neighborhood of the bearing  393 . 
     As shown in  FIG. 16  (a), a lever member  394  is rotatably supported by a support member  395  on the drive side of the developing unit  21 . Here, the support member  395  passes through a hole  394   a  of the lever member  394  and is fixed to a hole  326 Ra of a first side member  326 R. By this, the lever member  394  can rotate about the support member  395  and the hole  394   a  in the developing unit  21 . The lever member  394  is provided with a first pressing portion  394   c  on the side where the cleaning unit  61  will be assembled later and a second pressing portion  394   b  on the opposite side across the hole portion  394   a.    
     Part (b) of  FIG. 16  to part (d) thereof, when the developing unit  21  and the cleaning unit  61  are coupled with each other, the first pushing portion  394   c  of the lever member  394  passes through the cut-away portion  393   c  of the bearing  393  to approach to the slope portion  388   e  of the cam  388 . As shown in part (a) of  FIG. 16  and part (b) of  FIG. 16 , the cleaning frame  71  is provided with a second boss  71   b  on the side opposite to the developing unit  21  as viewed from the drum cylinder  62 . 
     Referring to  FIG. 17 , the operation of the lever member  394  and the drum gear unit U 31  in this embodiment will be described  FIG. 17  is an illustration of the operation of the lever member  394  and the drum gear unit U 31 . Part (a) of  FIG. 17  and part (b) of  FIG. 17  are perspective views, showing the state in which the positions of the lever members  394  are different from each other.  FIG. 17  (c) is a sectional view of the state of  FIG. 17  (b) taken along a plane S 6 , and for the sake of explanation, the coupling member  386  and the pin  391  are shown without sectioning. When the lever member  394  rotates in the direction R 5  from the state shown in  FIG. 17  (a) as shown in  FIG. 17  (b), the first pressing portion  394   c  moves in a direction approaching the contact surface  393   b  so as to abut to and interfere with the inclined surface portion  388   e  of the cam  388 . Then, the inclined surface portion  388   e  abuts to the first pressing portion  394   c  and the contacted surface  388   d  abuts to the contact surface  393   b  of the bearing  393 , respectively, so that the cam  388  moves in the direction of an arrow X 5  while being sandwiched between the first pressing portion  394   c  and the contact surface  393   b . By this, the coupling member  386  also moves in the direction of the arrow X 5  by way of the pin  391 . 
     Referring to  FIG. 18 , the operation of the lever member  394  and the drum gear unit U 31  when this cartridge B is mounted in the apparatus main assembly A will be described.  FIG. 18  is an illustration of mounting the cartridge B in the apparatus main assembly A. Part (a 1 ) of  FIG. 18  and part (a 3 ) thereof show state in the process of mounting, and  FIG. 18  (a 3 ) shows the state in which the mounting is completed. 
     Part (b 1 ) of  FIG. 18 to 18  (b 3 ) are sectional views taken along a cutting line S 7  of  FIG. 18  (a 1 ) to  FIG. 18  (a 3 ), and for the purpose of better illustration, some parts are shown not in sectional view. as shown in  FIG. 18  (a 1 ), when mounting the cartridge B in the apparatus main assembly A, the cartridge B is mounted while being rotated in the direction of the arrow R 4 . Then, the cartridge B can rotate until the second boss  71   c  comes into contact with the second guide lower surface portion  12   d  provided on the guide  12  of the apparatus main assembly A. At this time, the second pressing portion  394   b  of the lever member  394  abuts against the first guide upper surface portion  12   b  of the guide  12 , and the lever member  394  rotates in the direction of the arrow R 5  about the supporting member  395 . Then, as described above, the coupling member  386  becomes in the stage having moved in the direction of the arrow X 5  as shown in  FIG. 18  (b 1 ). As the cartridge B is going to be mounted in this state in the direction of the arrow X 2 , the projection  386   c   1  of the coupling member  386  passes through the drive head  14  and the coupling member  386  moves to the guide member  15  as shown in  FIG. 18  (b 2 ). Finally, as shown in  FIG. 18  (a 3 ), the cartridge B is rotated in the direction of the arrow R 6  until the second boss  71   c  and the second guide upper surface portion  12   c  contact each other. Then, the coupling member  386  and the cam  388  move in the direction of the arrow X 4  by the urging force of the compression spring  390 , and at the same time, the lever member  394  rotates about the support member  395  in the direction of arrow R 7  by the contact between the slanted portion  388   e  and the first push portion  394   c . in this manner, the coupling member  386  moves in the direction of the arrow X 4  and becomes engageable with the driving head  14 , and the mounting of the cartridge B on the apparatus main assembly A is completed. 
     In this state, when the drive head  14  rotates, the drive pin of the drive head  14  contacts the projection  386   c   1 , so that the rotational force is transmitted to the projection  386   c   1 . The contact portion of the projecting portion  386   c   1  in contact with the driving pin is a force receiving portion for receiving the rotational force from the driving pin. The coupling member  386  and the drum cylinder  62  are rotated by the rotational force received by the projecting portion  386   c   1 . 
     On the other hand, when taking the cartridge B out of the apparatus main assembly A, the coupling member  386  and the lever  394  operate in the direction opposite to that when the cartridge B is mounted. the coupling member  386  retracts away from the drive head  14  in the axial direction, and therefore, the engagement between the coupling member  386  and the drive head  14  is broken. The cartridge B can be removed from the main assembly of the apparatus. 
     Also in this embodiment, like the Embodiment 1 and the Embodiment 2, the projection  386   c   1  of the coupling member  386  has a shape that expands in the radial direction of the coupling member  386  as it goes to the tip (free end) thereof. Therefore, in the process of mounting and dismounting the cartridge B, the projecting portion  386   c   1  can pass between the driving head  14  and the guide member  15 . 
     In this embodiment, the lever  394  rotates as the user changes the attitude of the cartridge B when the cartridge B is mounted to or dismounted from the apparatus main assembly A. However, a mechanism for assisting the attitude change of the cartridge B may be provided in the apparatus main assembly A or the cartridge B when the cartridge B is mounted or removed. For example, a cartridge B is provided with a spring, and when the cartridge B is mounted or dismounting, the spring is brought into contact with the device main assembly A or is hooked. the attitude of the cartridge B is changed by the elastic force of the spring or the like in such an example. 
     Embodiment 4 
     Hereinafter, Embodiment 4 will be described referring to  FIGS. 19 to 23 . The coupling member (coupling unit U 41 ) of this embodiment has a first portion (translating portion  499 ) and a second portion (inclining movement portion  494 ). The translating portion (first part)  499  is connected to the inclining movement portion  494  capable of tilting movement. As the inclining movement portion  494  is inclined and moved, the translating portion  499  of the coupling member moves forward and backward in the axial direction. 
     The translating portion  499  is a portion rotatable about the axis L 2  and the inclining movement portion  494  is a portion rotatable about the axis L 3 . 
     Referring to  FIG. 19  first, structure of the coupling unit U 41  and the bearing unit U 42  will be described. 
     Part (a) of  FIG. 19  and part (b) of  FIG. 19  are exploded perspective views of the coupling unit U 41 . 
     Part (c) of  FIG. 19  and part (d) of  FIG. 19  are exploded perspective views of the bearing unit U 42  including the coupling unit U 41 . As shown in  FIG. 19  (a) and  FIG. 19  (b), the coupling unit U 41  comprises the translating portion  499  of the coupling member, a rectilinear guide member  489 , and a connecting member  488 . The translation portion  499  of the coupling member is supported so as to be rotatable relative to the rectilinear guide member  489  by a shaft portion  499   a  being supported by a support portion  489   a . And, a female threaded portion  499   b  is coupled with a male threaded portion  488   b , by which the translating portion  499  of the coupling member and the connecting member  488  are integrally coupled. Here, the translating portion  499  of the coupling member has a coupling portion  499   c  on the side opposite to the female screw portion  499   b  in the direction of the axis L 2 . The connecting member  488  also has a cavity  488   c  on the side opposite to the male threaded portion  488   b  in the direction of the axis L 2  and a hole  488   d  communicating with the cavity  488   c.    
     As shown in part (c) of  FIG. 19  and part (d) of  FIG. 19 , the bearing unit U 42  comprises the coupling unit U 41 , an operation member (slide member  490 ), a compression spring  491 , and a bearing member  492 . The slide guide  490  is movably connected a bearing member  492   d  so as to be rotatable in the direction perpendicular to the axis L 2  by a guided portion  490   d  being supported by the guide groove  492   d  of the bearing member  492 . The sliding member  490  is an operating member which moves the coupling unit U 41  by linear movement thereof. 
     Here, the direction in which the slide guide  490  can move is the same as the mounting direction (arrow X 2  direction) of the cartridge B as will be described hereinafter. Between the slide guide  490  and the bearing member  492 , the compression spring  491  is provided so as to be supported by a projection  490   c  and a projection  492   c . By this, the slide guide  490  is urged to move relative to the bearing member  492  in the direction of the arrow X 2 . The supported unit  489   b  of the rectilinear guide unit  489  is press-fitted and fixed to the support unit  490   a  of the slide guide  490 , by which the coupling unit U 41  is connected to the slide guide  490 . With the above-described structure, the translating portion  499  of the coupling member is connected to the bearing member  492  so as to be movable in the direction of the axis L 2  and the mounting direction (arrow X 2 ) relative to the bearing member  492 . 
     Referring to  FIG. 20 , the structure of the drive transmission unit U 43  will be described.  FIG. 20  is an exploded perspective view of the drive transmission unit U 43 . As shown in  FIG. 20  (a) and  FIG. 20  (b), the drive transmission unit U 43  comprises the bearing unit U 42 , the inclined moving portion  494 , and a connecting pin  493 . The inclining movement portion  494  is provided with a first spherical portion  494   a  and a second spherical portion  494   c . The first spherical portion  494   a  is provided with a hole portion  494   b , and the second spherical portion  494   c  is provided with a projection portion  494   d . The first spherical portion  494   a  is inclinably fitted into the cavity portion  488   c  of the connecting member  488 , and the pin  493  communicates the hole portion  488   d  of the connecting member  488  with the hole portion  494   b  of the inclining movement portion  494 . By this, the connecting member  488  and the inclining movement portion  494  are connected so as to be inclined along the spherical surface of the first spherical portion  494   a.    
     Further, referring to  FIG. 21 , a structure in which the drive transmission unit U 43  is connected to the drum cylinder  62  will be described. 
     Part (a) of  FIG. 21  is an exploded perspective view of the cleaning unit  61 , and  FIG. 21  (b) is a perspective view illustrating only the drum cylinder  62 , a drive side flange (drum gear)  487 , and the inclined movement portion  494 . As shown in  FIG. 21  (a), a driving side flange  487  is fixed to a driving side end portion of the drum cylinder  62 . In the drive transmission unit U 43 , the bearing member  492  is fixed to the cleaning frame  71  and rotatably supports the driving side flange  487 . As shown in  FIG. 21  (b), the drive side flange  487  is provided with a cavity  487   a , a rear end retaining portion  487   c  a second retaining portion  487   d  which project radially inward from the cavity  487   a , and a drive transmission portion  487   b  communicating with the hollow portion  487   a  are provided. The inclining movement portion  494  is connected so that the second spherical portion  494   c  fits into the cavity portion  487   a  and the projecting portion  494   d  fits into the drive transmission portion  487   b , respectively. Here, the inner diameter of the second retaining portion  487   d  is slightly smaller than the second spherical portion  494   c . When inserting the second spherical portion  494   c  into the cavity portion  487   a , the second stopper portion  487   d  is deformed to allow entry of the second spherical portion  494   c  into the hollow portion  487   a , and after the assembly is completed, the second spherical portion prevents the second spherical portion  494   c  from disengaging from the hollow portion  487   a . With the above-described structure, the inclining movement portion  494  is connected to the driving side flange  487  so as to be inclinable about the second spherical portion  494   c.    
     Referring to  FIG. 22 , the operation of the translating portion  499  of the coupling member in the cartridge B of this embodiment will be described. 
     Part (a) of  FIG. 22  is a side view as viewed from the outside of the drive side, and part (b) of  FIG. 22  and part (c) of  FIG. 22  are sectional views taken along a line S 8 , in which the translating portion  499 , the connecting member  488  and the inclining movement portion  494  are shown without sectional view for better illustration.  FIG. 22  (b) shows a state in which the rotation axis L 2  of the translating unit  499  and the rotation axis L 1  of the driving side flange  487  are aligned with each other, and  FIG. 22  (c) shows a state where the axis L 1  and the axis L 2  are not aligned with each other. As shown in  FIG. 22  (b), when the axis L 2  is aligned with the axis L 1 , the inclined moving portion  494  stands upright and the compression spring  491  is in a compressed state. On the other hand, as shown in  FIG. 22  (c), when the urging force of the compression spring  491  is imparted to move the slide guide  490  in the direction of the arrow X 2 , the inclining movement portion  494  moves in the direction of the arrow R 8  with the movement of the translating portion  499 . Then, the translating portion  499  moves in the direction of the arrow X 5  as if it is pulled by the first spherical portion  494   a  together with the connecting member  488 . in this manner, when the axis L 1  and the axis L 2  are aligned with each other, the translation portion  499  most projects to the outside of the drive side, and also moves in the direction of the arrow X 5  along with the movement in the direction of the arrow X 2  from this state. Further, by the compression spring  491 , the translating portion  499  is urged to move in the direction of the arrow X 2  and the direction of the arrow X 5 . 
     Referring to  FIG. 23 , the operation of the translating portion  499  when this cartridge B is mounted on the apparatus main assembly A will be described.  FIG. 23  is an illustration of the mounting operation of the cartridge B.  FIG. 23  (a 1 ) to (a 3 ) sequentially shows the state in which the cartridge B is mounted, and  FIG. 23  (a 3 ) is the state in which the mounting is completed. Part (b 1 ) of  FIG. 23 to 23  (b 3 ) are sectional views of part (a 1 ) of  FIG. 23 to 23  (a 3 ) taken along a line S 9 . For the sake of better illustration, the translating portion  499 , the connecting member  488 , and the inclining movement portion  494  are shown in non-sectional state. When mounting the cartridge B to the main unit A, by the compression spring  491  acts and the translation unit  499  has moved in the direction of the arrow X 5  (and the arrow X 2  (and arrow X 2 )) as shown in part (a 1 ) of  FIGS. 23 and 23  Direction). Then, the projecting portion  499   c   1  of the translating portion  499  passes the leading end of the driving head  14 , and the cartridge B can be mounted. When the projecting portion  499   c   1  reaches the downstream side in the mounting direction X 2  of the drive head  14 , the leading end portion  490   e  of the slide guide  490  comes into contact with the terminal end portion  12   e , as shown in  FIG. 23  (a 2 ) and  FIG. 23  (b 2 ). When the cartridge B is further moved to the mounting direction X 2  side, the translation portion  499  starts to move so that the axis L 2  approaches the axis L 1  and projects in the direction of the arrow X 4 . Finally, as shown in  FIG. 23  (b 3 ), the axis L 2  coincides with the axis L 1 , the translating portion  499  projects to the driving side and becomes engageable with the driving head  14 . 
     On the other hand, when taking the cartridge B out of the apparatus main assembly A, the translating portion  499 , the inclined moving portion  494 , and the slide guide  490  perform an operation in a direction opposite to that when the cartridge B is mounted. 
     The translating portion  499  retracts away from the driving head  14 , and therefore, the engagement between the translating portion  499  and the driving head  14  is broken, and the cartridge B can be dismounted from the main assembly A of the apparatus. 
     Also in this embodiment, like the first to Embodiment 3s, the projection  499   c   1  of the translating portion  499  has a shape that expands in the radial direction of the translating portion  499  toward the tip (free end) thereof. Therefore, in the insertion and removal process of the cartridge B, the projecting portion  499   c   1  can pass between the driving head  14  and the guide member  15 . 
     The structure of this embodiment is summarized as follows. As the inclining movement portion  494  is inclined, the translating portion  499  moves along the axis L 2 .  FIG. 22  (b) shows a state in which the coupling member (coupling unit U 41 ) is in the projecting position (first position). In this state, the inclination of the axis L 3  of the inclining movement portion  494  relative to the axis L 2  of the translating portion  499  is small, and in this embodiment the angle of the axis L 3  with respect to the axis L 2  is substantially zero. At this time, the axis L 3  and the axis L 2  are substantially coaxial with the axis L 1  of the drum cylinder  62 . 
     On the other hand,  FIG. 22  (c) shows a state in which the coupling member (coupling unit U 41 ) is in the retracted position (second position). In this state, the inclining movement portion  494  is inclined with respect to the translating portion  499 . In other words, the axis L 3  is larger in angle with respect to the axis L 2  than when the coupling member (coupling unit U 41 ) is at the projecting position (first position). 
     By the coupling member (coupling unit U 41 ) moving from the projecting position shown in  FIG. 22  (b) to the retracted position shown in  FIG. 22  (c), the translating portion  499  moves along the axis L 2 . At this time, the axis L 2  of the translating portion  499  is kept substantially parallel to the axis L 1  of the drum flange  62 . 
     When the translating portion  499  moves along the axis L 2 , the distance between the axis L 2  and the axis L 1  changes. In other words, as the coupling member (coupling unit U 41 ) moves from the projecting position to the retracted position, the distance between the axis L 2  and the axis L 1  increases. 
     Further, the translating portion  499  is provided with a projecting portion  499   c  (see  FIG. 19 ). The projecting portion  499   c  has the same shape as the projecting portion  86   c   1  in the Embodiment 1. 
     In the first to Embodiment 4s, the interference of the drive head  14  with the coupling member is avoided by retracting the coupling member (that is, positioning it at the retracted position) when mounting the cartridge B and removing the cartridge B. At this time, not only the coupling member but also the drive head  14  may be retracted. 
     In other words, the drive head  14  may be mounted to the apparatus main assembly A with some play in its axial direction. In that case, the drive head  14  can move along the direction of the axis L 4  by the play. 
     When mounting or dismounting the cartridge B to or from the apparatus main assembly A, it is possible that when the coupling member and the driving head  14  come into contact with each other, the driving head  14  receives a force from the coupling member and retracts away from the coupling member. 
     INDUSTRIAL APPLICABILITY 
     A drum unit for a process cartridge capable of receiving a driving force from an image forming apparatus at an end portion is provided. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
         
           
               62 : drum cylinder 
               86 : coupling member