Patent Publication Number: US-2023161289-A1

Title: Cartridge and drum unit for electrophotographic image forming apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a cartridge and a drum unit usable for an electrophotographic type image forming apparatus such as a laser beam printer. 
     BACKGROUND ART 
     In the field of the electrophotographic type image forming apparatus, the structure is known in which elements such as a photosensitive drum and a developing roller as rotatable members contributable for image formation are unified as a cartridge which is detachably mountable to a main assembly of the image forming apparatus (main assembly). Here, in order to rotate the photosensitive drum in the cartridge, it is desirable to transmit a driving force thereto from the main assembly. It is known, for this purpose, to transmit the driving force through engagement between a coupling member of the cartridge and a driving force transmitting portion such as a drive pin of the main assembly side of the apparatus. 
     In some types of image forming apparatuses, a cartridge is demountable in a predetermined direction substantial perpendicular to a rotational axis of the photosensitive drum. In a known main assembly, the drive pin of the main assembly is moved in the rotational axis direction by an opening and closing operation of a cover of the main assembly. More particularly, a patent specification 1 discloses a structure in which a coupling member provided at an end portion of the photosensitive drum is pivotably relative to the rotational axis of the photosensitive drum. With this structure, the coupling member provided on the cartridge is engaged with the drive pin provided in the main assembly, by which the driving force is capable of being transmitted from the main assembly to the cartridge, as is known. 
     PRIOR ART REFERENCE 
     
         
         Japanese Laid-open Patent Application 2008-233867. 
       
    
     SUMMARY OF THE INVENTION 
     The present invention provides a further improvement of the above-described prior-art. 
     According to an aspect of the present invention, there is provided a cartridge mountable to a main assembly of an electrophotographic image forming apparatus, said coupling member comprising a pivotable coupling member, wherein the main assembly including a rotatable engaging portion for engaging with said coupling member, and a coupling guide, positioned downstream of a rotational axis of the engaging portion with respect to a mounting direction of said cartridge, for being contacted by said coupling member pivoted relative to the rotational axis of the engaging portion to guide said coupling member to be parallel with the rotational axis of the engaging portion, said cartridge being mountable to the main assembly in the mounting direction substantially perpendicular to the rotational axis of the engaging portion, said cartridge comprising a frame; a rotatable member for carrying a developer; and a rotatable force receiving member for receiving a rotational force to be transmitted to said rotatable member; said coupling member including a free end portion having a receiving portion for receiving the rotational force from the engaging portion and a connecting portion having a transmitting portion for transmitting the rotational force received by said receiving portion to said force receiving member, said frame including a hole portion for exposing said free end portion to an outside of said frame, and a receiving portion, provided in a downstream of said hole portion with respect to the mounting direction, for receiving said coupling member when said coupling member is inclined toward a downstream side with respect to the mounting direction and for receiving said coupling guide in place of said coupling member with engagement of said coupling member with the engaging portion. 
     According to another aspect of the present invention, there is provided a drum unit dismountable from a main assembly of an electrophotographic image forming apparatus by moving in a predetermined direction substantially perpendicular to a rotational axis of an engaging portion rotatably provided in the main assembly, wherein a rotatable coupling member is mountable to said drum unit, the coupling including a free end portion having a receiving portion for receiving a rotational force from said engaging portion, and a connecting portion having a transmitting portion for transmitting the rotational force received by said receiving portion, said connecting portion being provided with a through-hole, wherein said coupling member is mountable to said drum unit by holding opposite end portions of a shaft penetrating the through-hole, said drum unit comprising a cylinder having a photosensitive layer; and a flange mounted to an end portion of said cylinder, said flange being provided with an accommodating portion capable of accommodating the connecting portion and capable of pivotably holding coupling member, an annular groove portion in said accommodating portion outside with respect to a radial direction of said cylinder, and a holding portion for holding the opposite end portions of the shaft penetrating said through-hole, wherein said groove portion and said holding portion overlap along a rotational axis direction of said cylinder. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a sectional view of a main assembly of the image forming apparatus and a cartridge, according to an embodiment of the present invention. 
         FIG.  2    is a sectional view of the cartridge according to the embodiment of the present invention. 
         FIG.  3    is an exploded perspective view of the cartridge according to the embodiment. 
         FIG.  4    is an illustration of behavior in the mounting and demounting of the cartridge relative to the main assembly, according to the embodiment of the present invention. 
         FIG.  5    is an illustrations of behavior in the mounting and demounting of the cartridge relative to the main assembly with a pivoting action of the coupling member, according to the embodiment of the present invention. 
         FIG.  6    is an illustration of the coupling member according to the embodiment. 
         FIG.  7    is an illustration of a clearance space of the coupling member according to this embodiment. 
         FIG.  8    is an illustration of a drum unit according to the embodiment of the present invention. 
         FIG.  9    is an illustration of behavior in assembling of the drum unit into a cleaning unit. 
         FIG.  10    is there exploded view of the driving side flange unit according to the embodiment of the present invention. 
         FIG.  11    is a perspective view and a sectional view of a driving side flange unit according to the embodiment. 
         FIG.  12    is an illustration of an assembling method of the driving side flange unit, according to the embodiment. 
         FIG.  13    is an illustration of a bearing member, according to the embodiment. 
         FIG.  14    is an illustration of a bearing member, according to the embodiment. 
         FIG.  15    is an illustration of a behavior of the pivoting of the coupling member relative to an axis L 1 , in this embodiment. 
         FIG.  16    is a perspective view of a driving portion of a main assembly according to the embodiment of the present invention. 
         FIG.  17    is an exploded view of the driving portion of the main assembly according to the embodiment of the present invention. 
         FIG.  18    is an illustration of a driving portion of the main assembly according to the embodiment of the present invention. 
         FIG.  19    is an illustration illustrating the state in the process of mounting the cartridge to the main assembly according to the embodiment of the present invention. 
         FIG.  20    is an illustration illustrating the state in the process of mounting the cartridge to the main assembly according to the embodiment of the present invention. 
         FIG.  21    is an illustration illustrating the state in which the mounting of the cartridge to the main assembly of the apparatus has completed, in the embodiment of the present invention. 
         FIG.  22    is an illustration of a coupling guide in the embodiment of the present invention. 
         FIG.  23    is an illustration of dismounting of the cartridge from the main assembly in the embodiment of the present invention. 
         FIG.  24    is an illustration of dismounting of the cartridge from the main assembly in the embodiment of the present invention. 
         FIG.  25    is an illustration illustrating the state in the process of mounting the cartridge to the main assembly according to the embodiment of the present invention. 
         FIG.  26    illustrates the coupling member and an engaging portion of a main assembly side in the embodiment of the present invention. 
         FIG.  27    is an illustration of release operations between the coupling member and the main assembly side engaging portion when the cartridge according to the embodiment of the present invention is mounted to and dismounted from the main assembly. 
         FIG.  28    is an illustration of a coupling guide according to the embodiment of the present invention. 
         FIG.  29    illustrates a coupling member and a drive pin in the embodiment of the present invention. 
         FIG.  30    is an illustration of the cartridge and the coupling guide in the embodiment of the present invention. 
         FIG.  31    is an illustration of a bearing member, according to an embodiment. 
         FIG.  32    is an illustration of a bearing member, according to an embodiment. 
         FIG.  33    is an illustration of a bearing member, according to an embodiment. 
     
    
    
     EMBODIMENTS FOR CARRYING OUT THE INVENTION 
     Referring to the accompanying drawings, the embodiments of the present invention will be described. 
     Here, an electrophotographic image forming apparatus is an image forming apparatus using an electrophotographic type process. In the electrophotographic type process, an electrostatic image formed on a photosensitive member is developed toner. The developing system may be a one-component developing system, two-component developing system, dry type development or another system. An electrophotographic photosensitive drum comprises a drum configuration cylinder and a photosensitive layer thereon, usable with an electrophotographic type image forming apparatus. 
     A process means includes a charging roller, a developing roller and so on, which are actable on the photosensitive drum, for image formation. A process cartridge these cartridge including the photosensitive member or process means (cleaning blade, developing roller or the like) relating to the image formation. In the embodiment, a process cartridge comprises the photosensitive drum, the charging roller, the developing roller and the cleaning blade as a unit. 
     More particularly, it is a laser beam printer of the electrophotographic type widely usable as a multifunction machine, a facsimile machine, a printer or the like. Reference numeral or characters in the following descriptions are for referring to the drawings and do not limit the structure of the present invention. The dimensions or the like in the following descriptions are to clarify the relationships and do not limit the structure of the present invention. 
     A longitudinal direction of the process cartridge in the following description is a direction substantially perpendicular to a direction in which the process cartridge is mounted to the main assembly of the electrophotographic image forming apparatus. A longitudinal direction of the process cartridge is a direction parallel with a rotational axis of the electrophotographic photosensitive drum (direction crossing with a sheet feeding direction). A side of the process cartridge in the longitudinal direction thereof where the photosensitive drum receive a rotational force from the main assembly of the image forming apparatus is a driving side (driven side), and the opposite side is a non-driving side. In the following description, an upper part (upper side) is on the basis of the direction of gravity in the state that the image forming apparatus is installed, unless otherwise be described, and the opposite side is a lower part (lower side). 
     Embodiment 1 
     In the following, the laser beam printer according to this embodiment will be described in conjunction with the accompanying drawings. The cartridge in this embodiment comprises a photosensitive drum as a photosensitive member (image bearing member, rotatable member), and process means including a developing roller, a charging roller and a cleaning blade as a unit (process cartridge). The cartridge is detachably mountable to the main assembly. The cartridge is provided therein with a rotatable member (gear, photosensitive drum, flange, developing roller) which is rotatable by a rotational force from the main assembly Ad among them, a member for carrying and feeding a toner image is called carrying member. 
     Referring to  FIGS.  1  and  2   , a structure and an image forming process of the laser beam printer as the electrophotographic image forming apparatus will be described. And then, referring to  FIGS.  3  and  4   , the structure of the process cartridge will be described in detail. 
     1. Laser Beam Printer and Image Forming Process 
       FIG.  1    is a sectional view of a main assembly A of a laser beam printer (apparatus main assembly) which is an electrophotographic image forming apparatus and a process cartridge (cartridge B).  FIG.  2    is a sectional view of the process cartridge B. 
     The main assembly A is portions of the laser beam printer other than the process cartridge B. 
     Referring to  FIG.  1   , the structure of the laser beam printer is an electrophotographic image forming apparatus will be described. 
     The electrophotographic image forming apparatus shown in  FIG.  1    is a laser beam printer which uses electrophotographic technique and relative to a main assembly of which the process cartridge B is mountable and dismountable. When the process cartridge B is mounted to the apparatus main assembly A, the process cartridge B is disposed below a laser scanner unit  3  as exposure means (exposure device), with respect to the direction of gravity. 
     Below the process cartridge B, a sheet tray  4  accommodating sheets P (recording materials) on which images are formed by the image forming apparatus. 
     Furthermore, the apparatus main assembly A comprises a pick-up roller  5   a , a feeding roller pair  5   b , a feeding roller pair  5   c , a transfer guide  6 , a transfer roller  7 , a feeding guide  8 , a fixing device  9 , a discharging roller pair  10  and a discharging tray  11 , arranged in the order named from an upstream side along a sheet feeding direction X1. The fixing device  9  as fixing means comprises a heating roller  9   a  and a pressing roller  9   b.    
     Referring to  FIGS.  1  and  2   , the image forming process will be described. 
     In response to a print starting signal, a rotatable photosensitive drum  62  (drum  62 ) is rotated at a predetermined peripheral speed (process speed) in an arrow R. 
     A charging roller  66  supplied with a bias voltage is contacted to an outer peripheral surface of the drum  62  to electrically charge the outer peripheral surface of the drum  62  uniformly. 
     The laser scanner unit  3  as exposure means outputs a laser beam L modulated in accordance with image information inputted to the laser beam printer. The laser beam L passes through an exposure window  74  provided in an upper surface of the process cartridge B and scanningly impinges on the outer peripheral surface of the drum  62 . By this, a part on the charged photosensitive member is electrically discharged so that an electrostatic image (electrostatic latent image) is formed in the surface of the photosensitive drum. 
     On the other hand, as shown in  FIG.  2   , in a developing unit  20  as a developing device, a developer (toner T) in a toner chamber  29  is stirred and fed by a rotation of a feeding screw  43  as a feeding member into a toner supply chamber  28 . 
     The toner T as the developer is carried on a surface of a developing roller  32  as developing means (process means, rotatable member) by a magnetic force of a magnet roller  34  (fixed magnet). The developing roller  32  functions as a rotatable member for carrying and feeding the developer into a developing zone to develop an electrostatic image formed on the photosensitive member. The toner T which is to be fed into the developing zone is regulated in a layer thickness on the peripheral surface of the developing roller  3 , by a developing blade  42 . The toner T is triboelectrically charged between the developing roller  32  and the developing blade  42 . 
     The electrostatic image formed on the drum  62  is developed (visualized) by the toner T for carried on the surface of the developing roller. The drum  66  rotates in the direction of an arrow R, carrying a toner image provided by the development, 
     As shown in  FIG.  1   , in timed relation with the output of the laser beam, the sheet P is fed out of the sheet tray  4  disposed in the lower portion of the apparatus main assembly A, the pick-up roller  5   a , the feeding roller pair  5   b  and the feeding roller pair  5   c.    
     The sheet P is supplied into a transfer position (transfer nip) which is between the drum  62  and the transfer roller  7 , along the transfer guide  6 . In the transfer position, the toner image is sequentially transferred from the drum  62  as the image bearing member onto the sheet P as the recording material. 
     The sheet P having the transferred toner image is separated from the drum  62  as the image bearing member and is fed to the fixing device  9  along the feeding guide  8 . The sheet P passes through a fixing nip formed between the heating roller  9   a  and the pressing roller  9   b  in the fixing device  9 . In the fixing nip, the unfixed toner image on the sheet P is pressed and heated so that it is fixed on the sheet P. Thereafter, the sheet P having the fixed toner image is fed by the discharging roller pair  10  and is discharged onto the discharging tray  11 . 
     On the other hand, as shown in  FIG.  2   , on the surface of the drum  62  after the toner T is transferred onto the sheet, untransferred toner which has now been transferred onto the sheet remains on the drum surface. The untransferred toner is removed by a cleaning blade  77  contacting to the peripheral surface of the drum  62 . By this, the toner remaining on the drum  62  is removed, and the cleaned drum  62  is charged again to be used for the next image forming process. The toner (untransferred toner) removed from the drum  62  is stored in a residual toner chamber  71   b  of a cleaning unit  60 . 
     In this case, the charging roller  66 , the developing roller  32  and the cleaning blade  77  function as process means acting on the drum  62 . In the image forming apparatus of this embodiment, the untransferred toner is removed by the cleaning blade, but the present invention is applicable to a type (cleanerless type) In which the untransferred toner is adjusted in the electric charge and then collected simultaneously with the development by the developing device. In the cleanerless type, an assistance charging member (auxiliary charging brush or the like) for adjusting the electric charge of the untransferred toner also functions as the process means. 
     2. Structure of Process Cartridge 
     Referring to  FIGS.  2  and  3   , the structure of the process cartridge B will be described in detail. 
       FIG.  3    is an exploded perspective view of the process cartridge B as the cartridge. A frame of the process cartridge can be disassembled into a plurality of units. In this embodiment, the process cartridge B comprises two units, namely the cleaning unit  60  and the developing unit  20 . In this embodiment, the cleaning unit  60  including the drum  62  is connected with the developing unit  20  by two connection pins  75 , but the present invention is not limited to such a case, and for example, three unit structure may be employed. The present invention is also applicable to such a case in which the units are not connected with coupling members such as pins, but a part of the units is exchangeable. 
     The cleaning unit  60  comprises a cleaning frame  71 , the drum  62 , the charging roller  66 , the cleaning blade  77  and so on. A driving side end portion of the drum (cylinder)  62  as the rotatable member is provided with a coupling member  86  (coupling) as a driving force transmitting part. To the drum  62  as the rotatable member, a driving force is transmitted from the main assembly through the coupling member  86  (coupling). In other words, the coupling member  86  (coupling) as a drive transmission part is provided at the end portion (driven side end portion) where the drum  62  is driven by the apparatus main assembly A. 
     As shown in  FIG.  3   , the drum  62  (photosensitive drum) as the rotatable member is rotatable about a rotational axis L 1  (axis L 1 ) as the drum axis (rotational axis of the drum  62 ). The coupling member  86  as the driving force transmission member is rotatable about a rotational axis L 2  (axis L 2 ) as the coupling axis (rotational axis of the coupling). The coupling member  86  as the drive transmission member (driving force transmitting part) is inclinable (pivotable) relative to the drum  62 . In other words, the axis L 2  is inclinable relative to the axis L 1 , as will be described in detail hereinafter. 
     On the other hand, the developing unit  20  comprises a toner accommodating container  21 , a closing member  22 , a developing container  23 , a first side member  26 L (driving side), a second side member  26 R (non-driving side), a developing blade  42 , a developing roller  32  and a magnet roller  34 . The toner container  21  contains toner T as the developer in this provided with a feeding screw  43  (stirring sheet) as a feeding member for feeding the toner. The developing unit  20  is provided with a spring (coil spring  46  in this embodiment) as an urging member for applying an urging force to regulate an attitude of the developing unit  20  and the cleaning unit  60  relative to each other. Furthermore, the cleaning unit  60  and the developing unit  20  are rotatably connected with each other by connection pins  75  (connection pins, pins) as connecting members to constitute the process cartridge B. 
     More specifically, arm portions  23   a L,  23   a R provided opposite end portions of the developing container  23  with respect to the longitudinal direction of the developing unit  20  (axial direction of the developing roller  32 ) is provided at free end portions rotation holes  23   b L and  23   b R. The rotation holes  23   b L,  23   b R are in parallel with the axis of the developing roller  32 . 
     Longitudinal opposite end portions of the cleaning frame  71  which is a frame (casing) of the cleaning unit are provided with respective holes  71   a  for receiving the connection pins  75 . The arm portions  23   a L and  23   a R are aligned with a predetermined position of the cleaning frame  71 , and the connection pins  75  are inserted through the rotation holes  23   b L and  23   b R and the holes  71   a . By this, the cleaning unit  60  and the developing unit  20  are connected with each other rotatably about the connection pins  75  as the connecting members. 
     At this time, the coil spring  46  as the urging member mounted to the base portion of each of the arm portions  23   a L and  23   a R abuts to the cleaning frame  71 , so that the developing unit  20  is urged to the cleaning unit  60  about the connection pin  75 . 
     By this, the developing roller  32  as the process means is assuredly urged toward the drum  62  as the rotatable member. Opposite end portions of the developing roller  32  are provided with respective ring configuration spacers (unshown) as gap holding members, by which the developing roller  32  is spaced from the drum  62  by a predetermined gap. 
     3. Mounting and Dismounting of Process Cartridge 
     Referring to  FIGS.  4  and  5   , the description will be made as to the operation of mounting and dismounting of the process cartridge B relative to the apparatus main assembly A. 
       FIG.  4    is an illustration of mounting and demounting of the process cartridge B relative to the apparatus main assembly A. Part (a) of  FIG.  4    is a perspective view as seen from the non-driving side, and part (b) is a perspective view as seen from the driving side. The driving side is a longitudinal end portion where the coupling member  86  of the process cartridge B is provided. 
     The apparatus main assembly A is provided with a rotatably door  13 .  FIG.  4    shows the main assembly in a state that the door  13  is open. 
     Inside the apparatus main assembly A is provided with a drive head  14  as a main assembly side engaging portion and a guiding member  12  as a guiding mechanism. The drive head  14  is a drive transmission mechanism of the main assembly side for transmitting the driving force to the cartridge mounted thereto through engagement with the coupling member  86  of the cartridge. By the rotation of the drive head  14  after the engagement, the rotational force can be transmitted to the cartridge. The drive head  14  can be deemed as a main assembly side coupling in the sense that it is engaged with the coupling of the process cartridge B to transmit the driving force. The drive head  14  as the main assembly side engaging portion is rotatably supported by the apparatus main assembly A. The drive head  14  includes a drive shaft  14   a  as a shaft portion, a drive pins  14   b  as an applying portions for applying the rotational force ((b 3 ) of  FIG.  5   ). In this embodiment, it is in the form of a drive pin, another structure can be employed, for example, a projection (projection) or projections projecting from the drive shaft  14   a  outwardly in a radial direction, and the driving force is transmitted from the surface of the projection to the cartridge. As a further alternative, a drive pin  14   a  may be press-fitted into the hole provided in the drive shaft  14   a , and then is welded. In (b 1 ) to (b 4 ) of  FIG.  5   , hatched portions indicate cut surfaces. The same applies to the subsequent drawings. 
     The guiding member  12  is a main assembly side guiding member for guiding the process cartridge B in the apparatus main assembly A. The guiding member  12  may be a plate-like member provided with a guiding groove or a member for guiding the process cartridge B at the lower surface of the process cartridge B while supporting it. 
     Referring to  FIG.  5   , the description will be made as to the process of mounting and dismounting of the process cartridge B relative to the apparatus main assembly A, while the coupling member  86  while the driving force transmitting part is inclining (pivoting, swing, whirling). 
       FIG.  5    is an illustration of the mounting and dismounting of the process cartridge B relative to the main assembly A while the driving force transmitting part is inclining (pivoting, swing, whirling). Parts (a 1 ) to (a 4 ) of  FIG.  5    are enlarged views of the coupling member  86  and the parts therearound as seen from the driving side toward the non-driving side. Parts (b 1 ) of  FIG.  5    is a sectional view (S 1  sectional view) taken along a line S 1 -S 1  of (a 1 ) of  FIG.  5   . Similarly, (b 2 ), (b 3 ) and (b 4 ) of  FIG.  5    are sectional views (S 1  sectional views) taken along lines S 1 -S 1  of (a 2 ), (a 3 ) and (a 4 ) of  FIG.  5   . 
     The process cartridge B is mounted to the apparatus main assembly A in the process from (a 1 ) to (a 4 ) of  FIG.  5   , and the (a 4 ) of  FIG.  5    shows the state in which the mounting of the process cartridge B to the apparatus main assembly A is completed. In  FIG.  5   , the guiding member  12  and the drive head  14  as the parts of the apparatus main assembly A are shown, and the other members are parts of the process cartridge B. 
     An arrow X2 and an arrow X3 in  FIG.  5    are substantially perpendicular to a rotational axis L 3  of the drive head  14 . The direction indicated by the arrow X2 will be called X2 direction, and the direction indicated by the arrow X3 will be called X3 direction. Similarly, the X2 direction and the X3 direction are substantially perpendicular to the axis L 1  of the drum  62  of the process cartridge. In  FIG.  5   , the direction indicated by the arrow X2 is a direction in which the process cartridge B is mounted to the apparatus main assembly A (downstream with respect to the cartridge mounting direction). In the direction indicated by the arrow X3 is a direction in which the process cartridge B is dismounted from the main assembly (upstream with respect to the cartridge mounting direction). A mounting and demounting direction contains the directions indicated by the arrow X2 and the arrow X3. The mounting and the dismounting are carried out in the respective directions. The directions may be described by the upstream with respect to the mounting direction, the downstream with respect to the mounting direction, the upstream with respect to the dismounting direction or the downstream with respect to the dismounting direction depending on the convenience of the explanation. 
     As shown in  FIG.  5   , the process cartridge B is provided with a spring as an urging member (elastic member). In this embodiment, the spring is a twisting spring  91  (twisted coil spring, kick spring). The torsion coil spring  91  urges the coupling member such that a free end portion  86   a  of the coupling member is inclined toward the drive head  14 . In other words, it urges the coupling member  86  such that in the mounting process of the process cartridge B, the free end portion  86   a  is inclined toward the downstream with respect to the mounting direction perpendicular to the rotational axis of the drive head  14 . The process cartridge B advances into the apparatus main assembly A with this attitude (state) of the free end portion  86   a  of the coupling member  86  inclining toward the drive head  14  (detailed description will be made hereinafter). 
     In the rotational axis of drum  62  is the axis L 1 , the rotational axis of the coupling member  86  is the axis L 2 , and the rotational axis of the drive head  14  functioning main assembly side engaging portion is the axis L 3 . As shown in (b 1 ) to (b 3 ) of  FIG.  5   , the axis L 2  is inclined relative to the axis L 1  and the axis L 3 . The rotational axis of the drive head  14  is substantially coaxial with the rotational axis of the drive shaft  14   a . A driving side flange  87  is provided at an end portion of the drum  62  and is rotatable integrally with the drum  62 , and therefore, the rotational axis of the driving side flange  87  is coaxial with the rotational axis of the drum  62 . 
     When the process cartridge B is inserted to an extent shown in (a 3 ) and (b 3 ) of  FIG.  5   , the coupling member  86  contacts to the drive head  14 . In the example of (b 3 ) of  FIG.  5   , the drive pin  14   b  as the rotational force applying portion is contacted by a standing-by portion  86   k   1  of the coupling member. By the contact, the position (inclination) of the coupling member  86  is regulated, so that the amount of the inclination (pivoting) of the axis L 2  relative to the axis L 1  (axis L 3 ) gradually decreases. 
     In this embodiment, the drive pin  14   b  as the applying portion is contacted by the standing-by portion  86   k   1  of the coupling member. However, depending on the phases of the coupling member  86  and the drive head  14  in the rotational moving direction, the portion where the coupling member  86  and the drive head  14  contact to each other is different. Therefore, the contact positions in this embodiment is not limiting to the present invention. It will suffice if a portion of the free end portion  86   a  of the coupling member (the detailed will be described hereinafter) contacts to a portion of the drive head  14 . 
     When the process cartridge B is inserted to the mounting completion position, the axis L 2  is substantially coaxial with the axis L 1  (axis L 3 ) as shown in parts (a 4 ) and (b 4 ) of  FIG.  5   . In other words, the rotational axes of the coupling member  86 , the drive head  14  and the driving side flange  87  are all substantially coaxial. 
     By the engagement of the coupling member  86  provided in the process cartridge B with the drive head  14  as the main assembly side engaging portion in this manner, the transmission of the rotational force is enabled from the main assembly to the cartridge. When the process cartridge B is dismounted from the apparatus main assembly A, the process is the reciprocal, that is, from the state of (a 4 ) and (b 4 ) toward the state of (a 1 ) and (b 1 ) in  FIG.  5   . Similarly to the mounting operation, the coupling member  86  inclines relative to the axis L 1 , so that the coupling member  86  is disengaged from the drive head  14  as the main assembly side engaging portion. That is, the process cartridge B is moved in the X3 direction opposite from the X2 direction substantially perpendicularly to the rotational axis L 3  of the drive head  14 , and the coupling member  86  disengages from the drive head  14 . 
     The movement of the process cartridge B in the X2 direction or X3 direction may occur only in the neighborhood of the mounting completion position. In another position other than the mounting completion position, the process cartridge B may move in any direction. In other words, it will suffice if a track of movement of the cartridge immediately before the engagement or disengagement of the coupling member  86  relative to the drive head  14  is the predetermined direction which is substantially perpendicular to the rotational axis L 3  of the drive head  14 . 
     4. Coupling Member 
     Referring to  FIG.  6   , the coupling member  86  will be described. As regards the rotational direction, the clockwise direction may be called right-handed rotational direction, and the counterclockwise direction may be called left-handed rotational direction. A rotational moving direction R in  FIG.  6    is counterclockwise direction when the cartridge is seen from the driving side toward the non-driving side. 
     For the purpose of better explanation, an imaginary line will drawn on a planar view, and an imaginary plane will be drawn on a perspective view. When a plurality of imaginary lines are to be used, first imaginary line, second imaginary line, third imaginary line or the like will be used. Similarly, when a plurality of imaginary planes are to be used, first imaginary plane, second imaginary plane, third imaginary plane or the like will be used. An inside of the cartridge (inward direction of the cartridge) and an outside of the cartridge (outward of direction of the cartridge) are based on the frame of the cartridge, unless otherwise mentioned. 
     Part (a) of  FIG.  6    is a side view of the coupling member  86 . Part (b) of  FIG.  6    is a S 2  sectional view of the coupling member  86  along a line S 2 -S 2  of part (a) of  FIG.  6   . Part (b) of  FIG.  6    shows the coupling with the drive head  14  as the main assembly side engaging portion without cutting. 
     Part (c) of  FIG.  6    illustrates a state in which the coupling member  86  is engaged with the drive head  14 . It is a view of the coupling member  86  and the drive head  14  as seen in the direction indicated by an arrow V1 of part (a) of  FIG.  6    from the outside of the driving side end portion (end surface) of the cartridge and the drive head  14 . Part (d) of  FIG.  6    is a perspective view of the coupling member  86 . Part (e) of  FIG.  6    illustrates a neighborhood of a free end portion  86   a  (which will be described hereinafter), as seen in the direction along the receiving portions  86   e   1  and  86   e   2  for receiving the rotational force (a direction V2 in part (c) of  FIG.  6   ). 
     As shown in  FIG.  6   , the coupling member  86  mainly comprises three portions. Briefly, it comprises two end portions and a portion therebetween. 
     A first portion is a free end portion  86   a  engageable with the drive head  14  as the main assembly side engaging portion to receive the rotational force from the drive head  14 . The free end portion  86   a  includes an opening  86   m  expanding toward the driving side. 
     A second portion is a substantially spherical connecting portion  86   c  (accommodated portion). The connecting portion  86   c  is pivotably held (connected) by a driving side flange  87  which is a force receiving member. One end portion side of the drum (cylinder end portion) is provided with a driving side flange  87 , and the other end portion side is provided with a non-driving side flange  64 . 
     The first portion can be deemed as including the one end portion side of the coupling member, and the second portion can be deemed as including the other end portion side of the coupling member. The second portion can be deemed as including a rotational center when the coupling member rotates (pivots) in the state that the coupling member is held by the driving side flange  87 . 
     A third portion is an interconnecting portion  86   g  connecting the free end portion  86   a  and the connecting portion  86   c  with each other. 
     Here, a maximum rotation diameter φZ 2  of the interconnecting portion  86   g  is smaller than a maximum rotation diameter φZ 3  of the connecting portion  86   c  (φZ 2 &lt;φZ 3 ), and is smaller than a maximum rotation diameter φZ 1  of the free end portion  86   a  (φZ 2 &lt;Z 1 ). In other words, a diameter of at least a part of the interconnecting portion  86   g  is smaller than a diameter of a maximum diameter portion of the connecting portion. In addition, a diameter of at least a part of the interconnecting portion  86   g  is smaller than a diameter of a maximum diameter portion of the free end portion  86   a . These diameters are the maximum diameters about the rotational axis of the coupling member, and they are the maximum diameters of imaginary circles of the respective cross-sectional portions of the coupling member on an imaginary flat plane perpendicular to the rotational axis of the coupling member. 
     The maximum rotation diameter φZ 3  of the connecting portion  86   c  is larger than the maximum rotation diameter of the free end portion  86   a  (φZ 3 &gt;φZ 1 ). With such relationships, when the coupling member  86  is inserted into a hole having a diameter not less than φZ 1  and not more than φZ 3  from the free end portion  86   a  side, the coupling member  86  does not penetrate throughout the hole. For this reason, when and after a unit including the coupling member  86  is assembled up, the coupling member is prevented from the unit in which the coupling member is inserted. In this embodiment, the maximum rotation diameter φZ 1  of the free end portion  86   a  is larger than the maximum rotation diameter φZ 2  of the interconnecting portion  86   g  and is smaller than the maximum rotation diameter φZ 3  of the connecting portion  86   c  (φZ 3 &gt;φZ 1 &gt;φZ 2 ). 
     These maximum rotation diameters φZ 1 , φZ 2  and φZ 3  can be measured as shown in part (a) of  FIG.  6   . More particularly, the diameters of the respective portions of the coupling member are measured in longitudinal sections including the rotational axis of the coupling member, and the maximum measurements of the respective portions are the maximum diameters. The diameters may be based on a three dimensional view shape provided by the rotation of the coupling member about the rotational axis thereof. More particularly, with respect to each of the portions, a point furthest from the rotational axis in the radial direction is determined. A track of the point when the point is revolved about the rotational axis of the coupling member is used as an imaginary circle, and the diameter of the imaginary circle is deemed as the maximum rotation diameter of the portion. 
     As shown in part (b) of  FIG.  6   , the opening  86   m  includes a conical shape receiving surface  86   f  as an expanding portion expanding toward the drive head  14  in the state that the coupling member  86  is mounted to the apparatus main assembly A. The receiving surface  86   f  is provided by the member having an outer peripheral surface at the free end portion, and a recess  86   z  is formed in the free end portion by the receiving surface  86   f  projecting outwardly. The recess  86   z  includes an opening  86   m  (opening) in a side opposite from the drum  62  (cylinder) with respect to the axis L 2 . 
     As shown in parts (a) and (c), on a circumference extending about the axis L 2  at the extreme end portion of the free end portion  86   a , there are provided two claw portions  86   d   1  and  86   d   2  at point symmetry positions with respect to the axis L 2 . Standing-by portions  86   k   1  and  86   k   2  are provided circumferentially between claw portions  86   d   1  and  86   d   2 . In this embodiment, a pair of projections are provided, but only one such a projection may be provided. In such a case, the standing-by portion is that portion between the downstream side of the projection and the upstream side of the projection with respect to the clockwise direction. The standing-by portions are the spaces required for the drive pins  14   b  of the drive head  14  provided in the apparatus main assembly A to wait without contacting the claw portions  86   d . The spaces are greater than the diameters of the drive pin  14   b  as the applying portion for applying the rotational force. 
     The spaces function as plays when the cartridge is mounted to the apparatus main assembly A. In the radial direction of the coupling member  86 , the recess  86   z  is inside the claw portions  86   d   1  and  86   d   2 . A width of the claw portion  86   d  in the diametrical direction is substantially equivalent to a width of the standing-by portion. 
     As shown in part (c) of  FIG.  6   , when the transmission of the rotational force from the drive head  14  to the coupling member  86  is awaited, the drive pins  14   b  for applying the rotational force are in the standing-by portions  86   k   1  and  86   k   2 , respectively (preparatory position or stand-by position). Furthermore, in part (d) of  FIG.  6   , in upstream sides of the claw portions  86   d   1  and  86   d   2  with respect to a rotational direction indicated by a arrow R, there are provided receiving portions  86   e   1  and  86   e   2  for receiving a rotational force in a direction crossing with the R direction (part (a) of  FIG.  6   ), respectively. The R direction in the Figure is the direction in which the coupling rotates in the image formation as a result of receiving the driving force from the drive head  14  of the main assembly. 
     The drive head  14  for transmitting the drive into process cartridge B and the drive pins  14   b  constitutes a drive transmission mechanism. A member may have a plurality of functions, depending on the configuration of the drive head. In such a case, a surface of a member actually contacting and transmitting the drive is the member constituting the drive transmission mechanism. 
     In the state that the coupling member  86  is engaged with the drive head  14  and the drive head  14  is rotating, the surfaces of the drive pins  14   b  of the main assembly side contact side surfaces of the receiving portions  86   e   1  and  86   e   2  of the coupling member  86 . By this, the rotational force is transmitted from the drive head  14  as the main assembly side engaging portion to the coupling member  86  as the drive transmission part. 
     In the base portions of the receiving portions  86   e   1  and  86   e   2 , there are provided undercuts (clearance spaces)  86   n   1  and  86   n   2  concaved from the standing-by portions  86   k   1  and  86   k   2  toward the connecting portion  86   c . Referring to  FIG.  7   , the undercuts  86   n   1  and  86   n   2  will be described in detail. Part (b) of  FIG.  7    is a S 3  section of part (a) of  FIG.  7   . 
       FIG.  7    shows a state in which the coupling member  86  is inclined along the drive pins  14   b  for applying the rotational force, from the state in which the drive pins  14   b  contact the receiving portions  86   e   1  and  86   e   2 . As shown in  FIG.  7   , the undercuts  86   n   1  and  86   n   2  are provided to avoid interference between the standing-by portions  86   k   1  and  86   k   2  and the drive pins  14   b  when the coupling member  86  is inclined in the state that the receiving portions  86   e   1  and  86   e   2  and the drive pins  14   b  are in contact with each other. Therefore, when the entirety of the standing-by portions  86   k   1  and  86   k   2  are cut up toward the connecting portion  86   c , or when the drive pins  14   b  are shortened, the undercut may not be provided. However, in this embodiment, the undercuts  86   n   1  and  86   n   2  are provided taking into account that if the entirety of the standing-by portions  86   k   1  and  86   k   2  are cut toward the connecting portion  86   c , the rigidity of the coupling member  86  may lower. 
     As shown in part (c) of  FIG.  6   , in order to stabilize the rotational torque transmitted to the coupling member  86 , the receiving portions  86   e   1  and  86   e   2  are preferably provided at the point symmetry positions with respect to the axis L 2 . By doing so, a rotational force transmission radius is constant, and therefore, the rotational torque transmitted to the coupling member  86  is stabilized. In addition, in order to stabilize the position of the coupling member  86  receiving the rotational force, it is preferable that the receiving portions  86   e   1  and  86   e   2  are disposed the diametrically opposite positions (180° opposing). Particularly in the case that no flange around the receiving portion and the standing-by portion at the free end portion, as in this embodiment, it is preferable that the number of the receiving portions is two. In the case of an annular flange extending around the outer periphery of the receiving portion, the receiving portions are not exposed when seen from a radially outward position along the rotational axis. Therefore, the receiving portions are relatively easily protected during transportation of the cartridge, irrespective of the attitude of the coupling member. However, with the structure in which the receiving portions is not seen from the outside along the rotational axis of the coupling member by the provision of the flange, the flange tends to interfere with the engaging portion. 
     As shown in parts (d) and (e) of  FIG.  6   , in order to stabilize the position of the coupling member  86  receiving the rotational force, it is desirable that the receiving portions  86   e   1  and  86   e   2  are inclined at a angle θ 3  relative to the axis L 2  so that the free end portions approach to the axis L 2 . This is because, as shown in part (b) of  FIG.  6   , by the rotational torque transmitted to the coupling member  86 , the coupling member  86  is attracted toward the drive head  14  as in the main assembly side engaging portion. By this, the conical shape receiving surface  86   f  contacts the spherical surface portion  14   c  of the drive head  14 , by which the position of the coupling member  86  is further stabilized. 
     In this embodiment, the number of the claw portions  86   d   1  and  86   d   2  is two, but this number is not restrictive to the present invention and may be different as long as the drive pins  14   b  can enter the standing-by portions  86   k   1  and  86   k   2 . However, because of the necessity of the drive pins  14   b  entering the standing-by portions, the increase of the number of the claw portions may require reduction of the claw portions per se (width in the circumferential direction in part (c) of  FIG.  6   ). In such a case, it is preferable that two (a pair of) projections are provided as in this embodiment. 
     Furthermore, the receiving portions  86   e   1  and  86   e   2  may be provided radially inside the receiving surface  86   f . Or, the receiving portions  86   e   1  and  86   e   2  may be provided at positions radially outside the receiving surface  86   f  with respect to the axis L 2 . However, in this embodiment, the driving force from the drive head  14  is received by the side surfaces of the claw portions  86   d   1 ,  86   d   2  projected from the receiving surface  86   f  in the direction away from the drum  62  along the rotational axis. Therefore, the claw portions  86   d   1  and  86   d   2 , of the free end portion  86   a , for receiving the driving force from the apparatus main assembly are exposed. If an annular flange is provided sounding the projections (claws), the flange will interfere with a part therearound when the coupling member  86  is inclined, and therefore, the inclinable angle of the coupling member  86  is restricted. In addition, the provision of the annular flange may require that the parts therearound are disposed so as not to interfere, with the result of the upsizing of the cartridge B. 
     Therefore, the structure not having a portion other than the driving force receiving positions (claw portions  86   d   1 ,  86   d   2  in this embodiment) is contributable to the downsizing of the cartridge B (and main assembly A). On the other hand, without the flange surrounding the projections, the liability that the projections are conducted by the other parts during transportation increases. However, as will be described hereinafter, by urging the coupling member  86  by a spring, the claw portions  86   d   1  and  86   d   2  can be accommodating within a most outer configuration portion of the bearing member  76 . By this, the possibility of the damage of the claw portions  86   d   1 ,  86   d   2  during the transportation can be reduced. 
     In this embodiment, the projection amount Z 15  of the claw portions  86   d   1  and  86   d   2  from the standing-by portions  86   k   1  and  86   k   2  is 4 mm. This amount is preferable in order to assuredly engaging the claw portions  86   d   1  and  86   d   2  with the drive pins  14   b  without interference of the standing-by portions  86   k   1  and  86   k   2  with the drive pins  14   b , but may be another depending on the part accuracy. However, if the standing-by portions  86   k   1  and  86   k   2  are too far from the drive pin  14   b , the formation when the drive is transmitted to the coupling member  86  may increase. On the other hand, if the projection amount of the claw portions  86   d   1  and  86   d   2  is increased, the cartridge B and/or the apparatus main assembly A may be upsized. Therefore, the projection amount Z 15  is preferably in the range not less than 3 mm and not more than 5 mm. 
     In this embodiment, a length of the free end portion  86   a  in the direction of the axis L 1  is approx. 6 mm Therefore, the length of a base portion (portion other than the claw portions  86   d   1  and  86   d   2 ) of the free end portion  86   a  is approx. 2 mm, and as a result, the length of the claw portions  86   d   1  and  86   d   2  in the direction of the axis L 1  is longer than the length of the base portion (portion other than the claw portions  86   d   1  and  86   d   2 ). 
     An inner diameter φZ 4  of the receiving portions  86   e   1  and  86   e   2  is larger than the maximum rotation diameter φZ 2  of the interconnecting portion  86   g . In this embodiment, φZ 4  is larger than φZ 2  by 2 mm. 
     As shown in  FIG.  6   , the connecting portion  86   c  comprises a substantial spherical shape  86   c   1  having a pivoting center C substantially on the axis L 2 , arcuate surface portions  86   q   1  and  86   q   2 , and a hole portion  86   b.    
     The maximum rotation diameter φZ 3  of the connecting portion  86   c  is larger than the maximum rotation diameter φZ 1  of the free end portion  86   a . In this embodiment, φZ 3  is larger than φZ 1  by 1 mm. As for the spherical portion, a substantial diameter may be compared, and if it is partly cut for the convenience of molding, a diameter of an imaginary sphere may be compared. The arcuate surface portions  86   q   1  and  86   q   2  are on an arcuate plane provided by extending an arcuate configuration having the same diameter as the interconnecting portion  86   g . The hole portion  86   b  is a through-hole extending in the direction perpendicular to the axis L 2 . The through-hole  86   b  includes a first inclination-regulated portions  86   p   1  and  86   p   2  and transmitting portions  86   b   1  and  86   b   2  parallel with the axis L 2 . 
     The first inclination-regulated portions  86   p   1  and  86   p   2  have flat surface configurations equidistant from the center C of the spherical  86   c   1  (Z 9 =Z 9 ). The transmitting portions  86   b   1  and  86   b   2  have flat surface configurations equidistant from the center C of the spherical  86   c   1  (Z 8 =Z 8 ). A diameter of the pin  88  pivotably supporting the coupling member  86  through the hole portion  86   b  is 2 mm Therefore, the coupling member  86  is inclinable if Z 9  exceeds 1 mm. When Z 8  is 1 mm, the pin  88  can pass through the hole portion, and if Z 8  exceeds 1 mm, the coupling member  86  is rotatable about the axis L 1  by a predetermined amount. 
     The end portions, with respect to the direction perpendicular to the axis L 2 , of the hole portion  86   b  of the first inclination-regulated portions  86   p   1 ,  86   p   2  extend to outer edges of the arcuate surface portions  86   q   1  and  86   q   2 . The end portions, with respect to the direction perpendicular to axis L 2 , of the hole portion  86   b  of the transmitting portions  86   b   1 ,  86   b   2  extend to the outer edge of the spherical  86   c   1 . 
     In addition, as shown in  FIG.  6   , interconnecting portion  86   g  has a cylindrical shape connecting the free end portion  86   a  and the connecting portion  86   c , and is a columnar (or cylindrical) shaft portion extending substantially along the axis L 2 . 
     The material of the coupling member  86  in this embodiment may be resin material such as polyacetal, polycarbonate, PPS, liquid crystal polymer. The resin material may contain glass fibers, carbon fibers or the like, or metal inserted therein, so as to enhance the rigidity. In addition, the entirety of the coupling member  86  is made of metal or the like. In this embodiment, metal is used which is preferable from the standpoint of downsizing of the coupling. More particularly, it is made of zinc die-cast alloy. A part of the spherical surface of the connecting portion  86   c  is cut out at the portion close to the interconnecting portion  86   g  in the free end side  86   a . In addition, the configuration of the coupling member is so designed that the total length including the first to third portions is not more than approx. 21 mm A length from the pivoting center C to the free end portion engaging with the main assembly drive pin measured in the longitudinal direction is not more than 15 mm With the decrease of the distance from the center of the pivoting of the coupling member, the distance through which the coupling retracts from the drive pins when the coupling inclines by the same angle decreases. In other words, if the coupling member is shortened for the purpose of downsizing of the cartridge, it is necessary to increase the pivotable angle required to escape from the drive pin. The free end portion  86   a , the connecting portion  86   c , and the interconnecting portion  86   g  may be integrally molded, or may be provided by connecting different parts. In the state that the photosensitive drum, the coupling member and the flange supporting the coupling member is taken out of the cartridge, the coupling member is inclinable in any inclining directions. 
     5. Structure of Drum Unit 
     Referring to  FIGS.  8  and  9   , the structure of the photosensitive drum unit U 1  (drum unit U 1 ) will be described. 
       FIG.  8    is an illustration of the drum unit U 1 , in which part (a) is a perspective view as seen from the driving side, part (b) is a perspective view as seen from the non-driving side, and part (c) is an exploded perspective view.  FIG.  9    is an illustration of assembling the drum unit U 1  with the cleaning unit  60 . 
     As shown in  FIG.  8   , the drum  62 , the drum unit U 1  comprises a driving side flange unit U 2  for receiving the rotational force from the coupling member, the non-driving side flange  64  and a grounding plate  65 . The drum  62  as the rotatable member comprises an electroconductive member of aluminum or the like and a surface photosensitive layer thereon. The drum  62  may be hollow or solid. 
     The driving side flange unit U 2  as a force receiving member to which the rotational force is transmitted from the coupling member is provided at the driving side end portion of the drum  62 . More particularly, as shown in part (c) of  FIG.  8   , in the driving side flange unit U 2 , a fixed portion  87   b  of the driving side flange  87  which is a force receiving member is engaged in an opening  62   a   1  at the end of the drum  62  and is fixed to the drum  62  by bonding and/or clamping or the like. When the driving side flange  87  rotates, the drum  62  also rotates integrally therewith. The driving side flange  87  is fixed to the drum  62  such that a rotational axis as a flange axis of the driving side flange  87  substantially coaxial with the axis L 1  of the drum  62 . 
     Here, the substantial co-axial means the completely co-axial and approximately coaxial in which they are slightly deviated due to the manufacturing tolerances of the parts. The same applies to the following descriptions. 
     Similarly, the non-driving side flange  64  is provided at the non-driving side end portion of the drum  62  substantially coaxially with the drum  62 . In this embodiment, the non-driving side flange  64  is made of resin material. As shown in part (c) of  FIG.  8   , the non-driving side flange  64  is fixed to the opening  62   a   2  at the longitudinal end portion of the drum  62  by bonding and/or clamping or the like. The non-driving side flange  64  is provided with an electroconductive grounding plate  65  (main metal). The grounding plate  65  is in contact with the inner surface of the drum  62  and is electrically connected with the apparatus main assembly A. 
     As shown in  FIG.  9   , the drum unit U 1  is supported by the cleaning unit  60 . 
     In the non-driving side of the drum unit U 1 , a shaft receiving portion  64   a  (part (b) of  FIG.  8   ) of the non-driving side flange  64  is rotatably supported by the drum shaft  78 . The drum shaft  78  is press-fitted into the supporting portion  71   b  provided in the non-driving side of the cleaning frame  71 . 
     On the other hand, as shown in  FIG.  9   , in the driving side of the drum unit U 1 , there is provided a bearing member  76  for contacting and supporting the flange unit U 2 . A wall surface (plate-like portion)  76   h  as a base portion (fixed portion) of the bearing member  76  is fixed to the cleaning frame  71  by screws  90 . In other words, the bearing member  76  is fixed to the cleaning frame  71  by the screws. The driving side flange  87  is supported by the cleaning frame  71  and the bearing member  76  (the bearing member  76  will be described hereinafter. The supporting member is provided with projections inside and outside of the cartridge, respectively with respect to a reference surface which is a plate-like portion  76   h  of the bearing member  76 . The bearing member  76  which is the supporting member is a part of the frame of the cartridge, and therefore, the projection from the bearing member  76  can be deemed as a frame projection (projection). Similarly, the projection (first projection) for receiving the urging force from the main assembly Ad the projection (second projection) for mounting the spring can be deemed as projections extending from the frame, because the bearing member  76  is mounted to the body of the cartridge frame. In order to assure the strength or in view of shrinkage in the resin material molding, the bearing member  76  and the cartridge frame may be provided with a rib, a groove and/or a lightening recess provided at a position not described. 
     In this embodiment, the bearing member  76  is fixed to the cleaning frame  71  by screws  90 , but it may be fixed by bonding or by melted resin material. The cleaning frame  71  and the bearing member  76  may be made integral. 
     6. Driving Side Flange Unit 
     Referring to  FIGS.  10 ,  11  and  12   , the structure of the driving side flange unit U 2  will be described. 
       FIG.  10    is an exploded perspective view of the driving side flange unit U 2 , in which part (a) is a view as seen from the driving side, and part (b) is a view as seen from the non-driving side.  FIG.  11    is an illustration of the driving side flange unit U 2 , in which part (a) is a perspective view of the driving side flange unit U 2 , part (b) is a sectional view taken along S 4 -S 4  of part (a) of  FIG.  11   , part (c) is a sectional view taken along S 5 -S 5  of part (a) of  FIG.  11   .  FIG.  12    is an illustration of an assembling method for the driving side flange unit U 2 . 
     As shown in  FIGS.  10  and  11   , the driving side flange unit U 2  comprises the coupling member  86 , the pin  88  (shaft), the driving side flange  87 , a closing member  89  as the regulating member. The coupling member  86  is engageable with the drive head  14  to receive the rotational force. The pin  88  has a substantially circular column configuration (or cylindrical), and extends in the direction substantially perpendicular to the axis L 1 . The pin  88  receives the rotational force from the coupling member  86  to transmit the rotational force to the driving side flange  87 . The pin  88  as the shaft portion is provided with a rotation regulating portion for limiting rotation of the coupling member in the rotational moving direction by contacting a part of the through-hole in order to transmit the through engagement with the through-hole of the coupling member. 
     It is also provided with a pivoting regulating portion for limiting pivoting of the coupling member by contacting a part of the penetrating shaft in order to limit the pivoting of the pin  88  and the coupling member  86 . 
     The driving side flange  87  receives the driving force from the pin  88  to transmit the rotational force to the drum  62 . The closing member  89  as a regulating member functions to prevent disengagement of the coupling member  86  and the pin  88  for the driving side flange  87 . By this, the coupling member  86  is capable of taking various attitudes relative to the driving side flange  87 . In other words, the coupling member  86  is held pivotably about a pivoting center, so as to take a first attitude, a second attitude which is different from the first attitude or the like. As for the free end portion of the coupling member, it can take various positions (a position, a second position different from the first position). 
     As described in the foregoing, the driving side flange unit U 2  comprises a plurality of members, and the driving side flange  87  as a first member and the closing member  89  as a second member are unified into a flange. The driving side flange  87  functions both to receive the drive from the pin  88  and to transmit the drive to the drum  62 . On the contrary, the closing member  89  substantially out of contact to the inside of the drum and supports the pin  88  together with the driving side flange  87 . 
     Referring to  FIG.  10   , the constituent elements will be described. 
     As described hereinbefore, the coupling member  86  includes the free end portion  86   a  and the connecting portion  86   c  (accommodated portion). The connecting portion  86   c  is provided with a through hole portion  86   b . The inside (inner wall) of the hole portion  86   b  has transmitting portions  86   b   1  and  86   b   2  for transmitting the rotational force to the pin  88 . The inside (inner wall) of the hole portion  86   b  is also provided with first inclination-regulated portions  86   p   1  and  86   p   2  as inclination-regulated portions for being contacted by the pin  88  to limit the inclination amount of the coupling member  86  (also part (b 2 ) of  FIG.  15   ). A part of the peripheral surface of the pin  88  as the shaft portion functions as the inclination regulating portion (first inclination regulating portion). 
     The driving side flange  87  includes the fixed portion  87   b , a first cylindrical portion  87   j , an annular groove portion  87   p  and a second cylindrical portion  87   h . The fixed portion  87   b  is fixed to the drum  62  to transmit the driving force by contacting to the inner surface of the cylinder of the drum  62 . The second cylindrical portion  87   h  is provided inside the first cylindrical portion  87   j  in the radial direction, and the annular groove portion  87   p  is provided between the first cylindrical portion  87   j  and the second cylindrical portion  87   h . The first cylindrical portion  87   j  is provided with a gear portion (helical gear)  87   c  on the radially outside, and is provided with a supported portion  87   d  on the radially inside (annular groove portion  87   p  side). The gear portion  87   c  is preferably a helical gear from the standpoint of drive transmission property, but a spur gear is usable. The second cylindrical portion  87   h  of the driving side flange  87  is hollow configuration and has a cavity as an accommodating portion  87   i  therein. The accommodating portion  87   i  accommodates the connecting portion  86   c  of the coupling member  86 . In the driving side of the accommodating portion  87   i , there is provided a conical portion  87   k  as the disengagement prevention portion (overhang portion) for limiting disengagement of the coupling member  86  toward the driving side, by contacting to the connecting portion  86   c . More particularly, the conical portion  87   k  contacts to the outer periphery of the connecting portion  86   c  of the coupling member  86  to prevented the disengagement of the coupling member. More specifically, the conical portion  87   k  contacts to the substantially spherical portion of the connecting portion  86   c  to prevent the disengagement of the coupling member  86 . 
     Therefore, the minimum inner diameter of the conical portion  87   k  is smaller than the inner diameter of the accommodating portion  87   i . In other words, the conical portion  87   k  overhangs from the inner surface of the accommodating portion  87   i  toward the axis center of the coupling member (hollow portion side) to contact to the peripheral surface of the connecting portion  86   c  to prevent the disengagement. 
     In this embodiment, the conical portion  87   k  as a center shaft coaxial with the axis L 1 , but may be a spherical surface or a crossing with the axis L 1 . The driving side of the conical portion  87   k  is provided with an opening  87   m  for projecting the free end portion  86   a  of the coupling member  86 , and the diameter of the opening  87   m  (φZ 10 ) is larger than the maximum rotation diameter φZ 1  of the free end portion  86   a . In a further driving side of the opening  87   m , there is provided a second inclination regulating portion  87   n  as another inclination regulating portion contacting to the outer periphery of the coupling member  86  when the coupling member  86  is inclined (pivoted). More particularly, the second inclination regulating portion  87   n  contacts to the interconnecting portion  86   g  as a second inclination-regulated portion when the coupling member  86  is inclined. A gear portion  87   c  transmits the rotational force to the developing roller  32 . The supported portion  87   d  is supported by a supporting portion  76   a  of the bearing member  76  (supporting member) and is provided on the back side of the gear  87   c  with respect to the thickness direction thereof. They are coaxial with the axis L 1  of the drum  62 . 
     The structure is such that when the coupling member  86  contacts the first inclination regulating portion an inclination angle is smaller than when the coupling member  86  contacts the second inclination regulating portion, as will be described hereinafter. 
     The accommodating portion  87   i  inside the second cylindrical portion  87   h  is provided with a pair of groove portions  87   e  (recesses) extending in parallel with the axis L 1 , at 180° away from each other about the axis L 1 . The groove portion  87   e  opens toward the fixed portion  87   b  in the direction of the axis L 1  of the driving side flange  87  and continues to the hollow portion  87   i  in the diametrical direction. The bottom portion of the groove portion  87   e  is provided with a retaining portion  87   f  which is a surface perpendicular to the axis L 1 . The recess  87   e  is provided with a pair of receiving portions  87   g  for receiving the rotational force from the pin  88 , as will be described hereinafter. (at least a part of) the groove portion  87   e  and (at least a part of) the annular groove portion  87   p  overlap with each other in the axis L 1  direction (part (b) of  FIG.  12   ). Therefore, the driving side flange  87  can be downsized. 
     The closing member  89  as the regulating member is provided with a conical base portion  89   a , a hole portion  89   c  provided in the base portion  89   a , and a pair of projected portions  89   b  at positions approx. 180° away from each other about the axis of the base portion. The projected portion  89   b  includes a longitudinal direction regulating portion  89   b   1  at a free end with respect to axis L 1  direction. 
     In this embodiment, the driving side flange  87  is a molded resin material manufactured by injection molding, and the material thereof is polyacetal, polycarbonate or the like. The driving side flange  87  may be made of metal, depending on the load torque. In this embodiment, the driving side flange  87  is provided with a gear portion  87   c  for transmitting the rotational force to the developing roller  32 . However, the rotation of the developing roller  32  by be effected not through the driving side flange  87 . In such a case, the gear portion  87   c  may be omitted. The gear portion  87   c  is provided in the driving side flange  87  as in this embodiment, it is preferable that the gear portion  87   c  is integrally molded together with the driving side flange  87 . 
     Referring to  FIGS.  13  and  14   , the bearing member  76  will be described in detail.  FIG.  13    is an illustration showing only the bearing member  76  and parts therearound of the cleaning unit U 1 . Part (a) of  FIG.  13    is a perspective view as seen from the driving side. Part (b) of  FIG.  13    is a sectional view taken along a line S 61 -S 61  of part (a) of  FIG.  13   , part (c) of  FIG.  13    and part (d) of  FIG.  13    are perspective views. Part (e) of  FIG.  13    is a sectional view taken along a line S 62 -S 62  of part (a) of  FIG.  13   .  FIG.  14    is a perspective view of the bearing member  76 , part (a) of  FIG.  14    is a view as seen from the driving side, and part (b) of  FIG.  14    a view as seen from the non-driving side and also shows the driving side flange  87  for convenience of explanation. Part (c) of  FIG.  14    is a sectional view taken along S 71  plane of part (b) of  FIG.  14   . 
     As shown in  FIG.  14   , the bearing member  76  mainly comprises a plate-like portion  76   h , a first projected portion  76   j  projecting from plate-like portion  76   h  in one direction (driving side), a supporting portion  76   a  as a second projected portion projecting from the plate-like portion  76   h  in the other direction (non-driving side). The bearing member  76  further comprises a cut-away portion  76   k  as a retracted portion (receiving portion). The cut-away portion  76   k  as the retracted portion (receiving portion) is recessed from a reference surface of the bearing member  76 , and in this embodiment, it is a groove portion extending toward the downstream side with respect to the mounting direction. The recess is preferably in the form of a groove from the standpoint of assuring the rigid of the bearing member  76 , but the shape is not limited to this example. The recess from the reference surface is called retracted portion because it permits the coupling member to incline and retract, thus preventing interference between the coupling and the main assembly side drive pin. In other words, the recess from the reference surface is the receiving portion. This is because the inclined coupling member enters the recessed portion. A coupling guide of the main assembly side which will be described hereinafter is capable of entering the recess. It is not necessary that whole of the coupling member and/or the coupling guide enters the recess, but at least a part there of may enter. Therefore, the recess provided in the cartridge frame is a space for permitting retraction of the coupling and is a receiving portion for receiving the coupling member or the like. 
     More specifically, it will suffice if the coupling member inclining toward the downstream with respect to the mounting direction cartridge inclines (retracts) more than toward the directions, and the recess may have an expanding shape. The shape of the retracted portion (receiving portion) is not limited to a groove, but it will suffice if it is a recess extending toward the downstream beyond the rotational axis of the flange, with respect to the cartridge mounting direction. The first projected portion  76   j  is provided in a radially inside portion with a hollow portion  76   i  for accommodating the coupling member  86 , and the hollow portion  76   i  is spatially connected with the cut-away portion  76   k  the cut-away portion  76   j   1  provided in a part of the first projected portion  76   j . The cut-away portion  76   k  as the retracted portion is provided downstream of the hollow portion  76   i  with respect to the mounting direction (X2) of the process cartridge B. Thus, when the cartridge is mounted to the main assembly, the coupling member  86  is retractable (greatly pivotable) into the cut-away portion  76   k  as the retracted portion. 
     In addition, the cylindrical supporting portion  76   a  enters the annular groove portion  87   p  of the driving side flange  87  to rotatably support the supported portion  87   d.    
     Moreover, the first projected portion  76   j  is provided with a cylindrical portion  76   d  and a spring receiving portion  76   e  which function as a guided portion and a first positioned portion when the process cartridge B is mounted to the apparatus main assembly A. At a free end side of the cut-away portion  76   k  with respect to the mounting direction (X2), a free end portion  76   f  functioning as a second positioned portion is provided. The cylindrical portion  76   d  and the free end portion  76   f  and disposed at the positions different in the direction of the axis L 1  with the plate-like portion  76   h  and the cut-away portion  76   k  therebetween, and have concentric arcuate configurations having different diameters. 
     In this embodiment, the first cylindrical portion  87   j , the annular groove portion  87   p , the second cylindrical portion  87   h  and the groove portion  87   e  are overlapping in the direction of the axis L 1 . Therefore, the supporting portion  76   a  of the bearing member  76  entering the annular groove portion  87   p , the pin  88 , the  86   c   1  of the coupling member  86  and the gear portion  87   c  are overlapping in the direction of the axis L 1 . As described hereinbefore, the bearing member  76  is provided with the cut-away portion  76   k  recessed toward the non-driving side beyond the plate-like portion  76   h , and when the coupling member  86  is inclined (pivoted), a part of the coupling member  86  is accommodated in the cut-away portion  76   k . With this structure of the parts around the coupling member  86 , the inclination (pivoting) amount of the coupling member  86  can be made large assuredly, while reducing the amount of the projection of the bearing member  76  and/or the coupling member  86  toward the driving side as compared with the gear portion  87   c . Here, overlapping means that when parts of an object are projected on an imaginary line, the parts are overlapped. In other words, an imaginary plane (reference plane) is determined, on which the parts are projected, and if the projected parts are overlapped on the imaginary plane, the parts are overlapped. 
     As shown in part (e) of  FIG.  13   , when the coupling member  86  inclines toward the cut-away portion  76   k , the most outer configuration of the first projected portion  76   j  in the direction of the axis L 1  is outside of the (claw portions  86   d   1 ,  86   d   2 ) of the coupling member  86 . By this, the risk that the claw portions  86   d   1  and  86   d   2  of the coupling member  86  collide against the other part during the transportation can be reduced. 
     In this embodiment, the developing roller  32  pushes the drum  62  in the direction indicated by an arrow X7, as described hereinbefore. That is, the drum unit U 1  urged toward the cut-away portion  76   k . The cut-away portion side supporting portion  76   a R of the supporting portion  76   a  supporting (the driving side flange  87  of) the drum unit U 1  is provided with the cut-away portion  76   k . The supporting portion  76   a L in the opposite side not having the cut-away portion  76   k  has a higher rigidity than that of the cut-away portion side supporting portion  76   a R. Therefore, in this embodiment, the supported portion  87   d  is provided on the back side of the gear portion  87   c  with respect to the thickness direction to receive the inner surface of the driving side flange  87 . By doing so, the drum unit U 1  is substantially supported by the opposite side supporting portion  76   a L. That is, the cut-away portion side supporting portion  76   a R having a less rigidity receive a smaller load so that the supporting portion  76   a  is not easily deformed. 
     As shown in  FIG.  13   , the torsion coil spring  91  as the urging means (urging member) is provided at a position which is in the disengagement side Of the axis L 1  of the driving side flange  87  with respect to the mounting and demounting direction of the coupling member  86  and which is below the axis L 1 . The torsion coil spring  91  includes a cylindrical coil portion  91   c , a first arm  91   a  extending from the coil portion  91   c  and a second arm  91   b  (first end portion, second end portion). By the coil portion  91   c  being supported (locked) by a spring hook portion  76   g , the spring is mounted to the bearing member  76 . The spring hook portion  76   g  has a cylindrical portion which is taller than the coil portion  91   c  to prevent the torsion coil spring  91  from disengaging from the spring hook portion  76   g . The spring hook portion  76   g  has a portion having a substantially D-like configuration, and the projection penetrates the coil portion  91   c , by which the torsion coil spring  91  is mounted to the cartridge. In the state that the torsion coil spring  91  is mounted, diameter of the coil portion  91  is larger than the diameter of the spring hood portion  76   g . The spring hook portion  76   g  projects from the longitudinal end portion of the cartridge frame toward an outside of the cartridge along the rotational axis direction of the driving side flange. 
     The first arm  91   a  of the torsion coil spring  91  contacts a spring receiving portion  76   n  of the bearing member  76 , and the second arm  91   b  thereof contacts a connection  86   g  or a spring receiving portion  86   h  of the coupling member  86 . By this, the torsion coil spring  91  urges by an urging force F 1  such that the free end portion  86   a  of the coupling member  86  faces cut-away portion  76   k  side. A width Z 11  of the cut-away portion  76   k  is larger than the diameter φZ 1  of the free end portion  86   a  of the coupling member  86 , and therefore, the free end portion  86   a  has latitude of movement up and down directions. The coil portion  91   c  of the torsion coil spring  91  is below the axis L 1 , and therefore, the free end portion  86   a  and coupling member  86  is urged downwardly by the urging force F 1  and the gravity. By this, the axis L 2  of the coupling member  86  inclines toward the cut-away portion  76   k  relative to the axis L 1 , and the free end portion  86   a  inclines to contact to the lower surface  76   k   1 . In this embodiment, the free end portion  86   a  takes a position below the axis L 1  by the urging force F 1  of the torsion coil spring  91 . As will be described hereinafter in conjunction with  FIG.  23   , the coupling member  86  is inclined so that the free end portion  86   a  thereof takes the position lower than the axis L 1 . 
     As described above, the free end portion  86   a  of the coupling member  86  is inclined in the direction of approaching to the drive head  14 , by the torsion coil spring  91 . Depending on the mounting direction X2, the direction of gravity, the weight of the coupling member  86  or the like, the free end portion  86   a  of the coupling member  86  is directed in the X2 direction due to the weight of the coupling member. In such a case, the coupling member  86  may be directed toward the desired direction using the gravity without provision of the torsion coil spring  91  as the urging means (urging member). The coupling member  86  of this embodiment is urged by the torsion coil spring  91  to contact to the lower side surface of the cut-away portion  76   k  in the form of a groove. By this, the coupling member is sandwiched by the torsion coil spring and the lower side surface of the groove so that the attitude of the coupling member is stabilized. By properly arranging the torsion coil spring  91 , for example, the coupling member may be contacted to the upper part surface of the cut-away portion  76   k  in the form of the groove configuration. However, the coupling attitude can be stabilized more in the case of using the gravity than in the case of using the urging force of the spring against the gravity. 
     Referring to  FIG.  11   , the description will be made as to the supporting method and connecting method of the constituent parts. 
     The position of the pin  88  in the longitudinal direction of the drum  62  (axis L 1 ) is limited by the retaining portion  87   f  and the longitudinal direction regulating portion  89   b   1 , and the position thereof in the rotational moving direction (R direction) of the drum  62  is limited by the receiving portion  87   g . The pin  88  penetrates the hole portion  86   b  of the coupling member  86 . The play between the hole portion  86   b  and the pin  88  is set so as to permit pivoting of the coupling member  86 . With such a structure, the coupling member  86  is capable of inclining (pivoting, swing, whirling) in any directions relative to the driving side flange  87 . 
     By the connecting portion  86   c  of the coupling member  86  contacting to the accommodating portion  87   i , the movement of the driving side flange  87  in the radial direction is limited. By the connecting portion  86   c  contacting to the base portion  89   a  of the closing member  89 , the movement from the driving side toward the non-driving side is limited. Furthermore, by the contact between the spherical  86   c   1  and the conical portion  87   k  of the driving side flange  87 , the movement of the coupling member  86  from the non-driving side toward the driving side is limited. By the contact between the pin  88  and the transmitting portions  86   b   1 ,  86   b   2 , the movement of the coupling member  86  in the rotational moving direction (R direction) is limited. By this, the coupling member  86  is connected with the driving side flange  87  and the pin  88 . 
     Here, as shown in part (d) of  FIG.  11   , a width Z 12  of the hole portion  86   b  is larger than the diameter φZ 13  of the pin  88 . By doing so, the coupling member  86  and the pin  88  are connected with each other with a play in the rotational moving direction (R direction) of the drum  62 , and therefore, the coupling member  86  can rotate through a predetermined amount about the axis L. 
     As described above, the position of the coupling member  86  in the axis L 1  direction is limited by the contact to the base portion  89   a  or conical portion  87   k , but because of the tolerances of parts, the coupling member  86  is made movable in the axis L 1  direction through a small distance. 
     Referring to  FIG.  12   , an assembling method of the driving side flange unit U 2  will be described. 
     As shown in part (a)  FIG.  12   , the pin  88  is inserted into the through hole portion  86   b  of the coupling member  86 . 
     Then, as shown in part (a) of  FIG.  12   , the pin  88  and the coupling member  86  are inserted into the accommodating portion  87   i  (along the axis L 1 ) with the phase of the pin  88  matching the pair of groove portions  87   e  of the driving side flange  87 . 
     As shown in part (b) of  FIG.  12   , the pair of projected portions  89   b  of the closing member  89  as the regulating member is inserted into the pair of groove portions  87   e , and in this state, the closing member  89  is fixed to the driving side flange  87  by welding or bonding. 
     In this embodiment, the diameter φZ 1  of the free end portion  86   a  of the coupling member  86  is smaller than the diameter φZ 10  of the opening  87   m . By this, the coupling member  86 , the pin  88  and the closing member  89  can all be assembled into the driving side, and therefore, the assembling is easy. In addition, the diameter φZ 3  of the connecting portion  86   c  is smaller than the diameter of the opening  87   m , by which the spherical surface portion  86   c   1  and the conical portion  87   k  can be contacted with each other. By this, the disengagement of the coupling member  86  toward the driving side can be prevented, and the coupling member  86  can be held with high precision. Because of the relationship of φZ 1  (&lt;φZ 10 )&lt;φZ 3 , the driving side flange unit U 2  can be easily assembled, and the position of the coupling member  86  can be maintained with high precision. 
     7. Inclining (Pivoting) Operation of Coupling 
     Referring to  FIG.  15   , the inclining (pivoting) operation of the coupling member  86  will be described. 
       FIG.  15    is an illustration of inclination (pivoting) of the coupling member  86  (including the axis L 2 ) relative to the axis L 1 . Parts (a 1 ) and (a 2 ) of  FIG.  15    is a perspective view of the process cartridge B in the state in that the coupling member  86  is inclined (pivoted). Part (b 1 ) of  FIG.  15    is a sectional view taken along a line S 7 -S 7  of (a 1 ) of  FIG.  15   . Part (b 2 ) of  FIG.  15    is a sectional view taken along a line S 8 -S 8  of (a 2 ) of  FIG.  15   . 
     Referring to  FIG.  15   , the inclination (pivoting) of the coupling member  86  about the center of the sphere of the connecting portion  86   c  will be described. 
     As shown in (a 1 ) and (b 1 ) of  FIG.  15   , the coupling member  86  is capable of inclining about the axis of the pin  88  about the center of the sphere of the connecting portion  86   c  relative to the axis L 1 . More specifically, the coupling member  86  is capable of inclining (pivoting) to such an extent that the second inclination-regulated portion (a part interconnecting portion  86   g ) contacts to the second inclination regulating portion  87   n  of the driving side flange  87 . Here, the inclination (pivoting) angle relative to the axis L 1  is a second inclination angle θ 2  (second inclination amount, second angle). The phase relation between the hole portion  86   b  and the claw portions  86   d   1 ,  86   d   2  are selected such that any one of the claw portion  86   d   1  and the claw portion  86   d   2  takes a leading position with respect to the direction in which the coupling member  86  inclines (arrow X7 direction) when the coupling member  86  inclines about the axis of the pin  88 . More particularly, the hole portion  86   b  and the claw portions  86   d   1 ,  86   d   2  are disposed such that the free end  86   d   11  of the claw portion  86   d   1  is not less than 59° and not more than 77° relative to an imaginary line penetrating through the center of the hole portion  86   b  (θ 6  and θ 7 ) in part (e) of  FIG.  11   ). The angles θ 6  and θ 7  are not limited to the examples, and preferably in the range not less than approx. 55° and not more than approx. 125° With such a structure, when one of the claw portions  86   d   1 ,  86   d   2  is in a leading position with respect to the inclination of the coupling member  86 , the pin  88  takes a large angle position (not less than approx. 55° and not more than approx.) 125° relative to the direction of inclination of the coupling member  86 . Then, the coupling member  86  can incline to the second inclination amount or the amount close thereto, that is, it can incline to a larger amount then the first inclination amount which will be described hereinafter. Thus, the free end  86   d   11  can be retracted greatly in the axis L 1  direction. 
     As shown in (a 2 ) and (b 2 ) of  FIG.  15   , the coupling member  86  is capable of inclining (pivoting) relative to the axis L 1  about the center of the sphere of the connecting portion  86   c  around the axis perpendicular to the axis of the pin  88  to a extent that the first inclination-regulated portions  86   p   1  and  86   p   2  contact to the pin  88 . Because of the above-described phase relation between the hole portion  86   b  (pin  88 ) and the claw portions  86   d   1 ,  86   d   2 , the coupling member  86  inclines (pivots) about an axis perpendicular to the axis of the pin  88 . At this time, the claw portions  86   d   1  and  86   d   2  are in the positions which are opposed to each other across the direction (arrow X8 direction) of the inclination of the coupling member  86 . The inclination (pivoting) angle relative to the axis L 1  is a first inclination angle θ 1  (first inclination amount, first angle). In this embodiment, the coupling member  86 , the driving side flange  87  and the pin  88  are constructed such that first inclination angle θ 1 &lt;second inclination angle θ 2  is satisfied, for the reasons which will be described hereinafter with  FIG.  25   . 
     By combination of the inclination (pivoting) about the axis of the pin  88  and the inclination (pivoting) about the axis perpendicular to the axis of the pin  88 , the coupling member  86  is capable of inclining (pivoting) in a direction different from those described above. Because the inclination (pivoting) in any directions are provided by the combination, the inclination (pivoting) angle in any direction is not less than first inclination angle θ 1  and not more than second inclination angle θ 2 . In other words, the coupling is pivotable not less than the first inclination angle θ 1  (first pivoting angle) and the second inclination angle (second pivoting angle) 
     In this manner, the coupling member  86  can incline (pivot) relative to the axis L 1  substantially all directions. In other words, the coupling member  86  can incline (pivot) relative to the axis L 1  in any directions. That is, the coupling member  86  can swing relative to the axis L 1  in any directions. Further, the coupling member  86  can whirl relative to the axis L 1  in any directions. Here, the whirling of the coupling member  86  is revolving of the inclined (pivoted) axis L 2  around the axis L 1 . 
     As described above, the arcuate surface portions  86   q   1  and  86   q   2  determine the first inclination angle θ 1 , and the interconnecting portion  86   g  has a dimension determining the second inclination angle θ 2 . Therefore, the diameters of the interconnecting portion  86   g  and the arcuate surface portions  86   q   1  and  86   q   2  may be different from each other, although they are the same in this embodiment. 
     8. Driving Portion of the Apparatus Main Assembly 
     Referring to  FIG.  16    toward  FIG.  18   , a structure of the cartridge driving portion of the apparatus main assembly A will be described. 
       FIG.  16    is a perspective view of the driving portion of the apparatus main assembly A (neighborhood of the drive head  14  of part (a) of  FIG.  4   ), as seen from an upstream inside of the apparatus main assembly A with respect to the mounting direction (X2 direction) of the process cartridge B.  FIG.  17    is an exploded perspective view of the driving portion, part (a) of  FIG.  18    is a partly enlarged view of the driving portion, and part (b) of  FIG.  18    is a sectional view taken along a cutting plane S 9 -S 9  of part (a) of  FIG.  18   . 
     The cartridge driving portion comprises a drive head  14  as the main assembly side engaging portion, a first side plate  350 , a holder  300 , a driving gear  355  and so on. 
     As shown in part (b) of  FIG.  18   , a driving shaft  14   a  of the drive head  14  as the main assembly side engaging portion is non-rotatably fixed to the driving gear  355  by a means (unshown). Therefore, when the driving gear  355  rotates, the drive head  14  as the main assembly side engaging portion also rotates. The driving shaft  14   a  is rotatably supported by a supporting portion  300   a  of the holder  300  and a bearing  354  at the respective end portions. 
     As shown in part (b) of  FIGS.  17  and  18   , a motor  352  as the driving source is mounted to a second side plate  351 , and the rotation shaft thereof is provided with a pinion gear  353 . The pinion gear  353  is engaged with the driving gear  355 . Therefore, when the motor  352  rotates, the driving gear  355  rotates, and the drive head  14  as the main assembly side engaging portion also rotates. The second side plate  351  and the holder  300  are fixed to the first side plate  350 . 
     As shown in  FIGS.  16  and  17   , the guiding member  12  as the guiding mechanism includes a first guiding member  12   a  and a second guiding member  12   b  for guiding the mounting of the process cartridge B. At a terminal end of the first guiding member  12   a  with respect to the cartridge mounting direction (X2 direction), a mounting end portion  12   c  perpendicular to the X2 direction is provided. The guiding member  12  is also fixed to the first side plate  350 . 
     As shown in  FIGS.  17  and  18   , the holder  300  is provided with the supporting portion  300   a  for rotatably supporting the driving shaft  14   a  of the drive head  14  as the main assembly side engaging portion, and a coupling guide  300   b . The coupling guide  300   b  is positioned downstream of the supporting portion  300   a  with respect to the mounting direction (X2 direction) of the process cartridge B (rear side of the main assembly), and is provided with an interconnecting portion  300   b   1  and a guide portion  300   b   2 . Here, the interconnecting portion  300   b   1  has an arcuate configuration of a diameter φZ 5  about the axis L 3 , in which the diameter φZ 5  is selected so as to be larger than the maximum rotation diameter φZ 2  of the free end portion  86   a  of the coupling member  86 . A free end of the guide portion  300   b   2  has an arcuate configuration of a diameter φZ 6  about the axis L 3 . The diameter φZ 6  is determined relative to the interconnecting portion  86   g  of the coupling member  86  so as to provide a predetermined gap S therebetween. The predetermined gap S is provided to prevent interference between the interconnecting portion  86   g  and the guide portion  300   b   2  in consideration of tolerances or the like, when the process cartridge B is rotated (which will be described hereinafter with  FIG.  22   ). 
     9. Mounting of Process Cartridge to Apparatus Main Assembly 
     Referring to  FIG.  19    to  FIG.  22   , mounting of the process cartridge B to the apparatus main assembly A will be described. In  FIGS.  19    and, the parts other than those required for the description of the mounting operation are omitted. 
     Part (a) of  FIGS.  19 ,  20  and  21    is a view of the apparatus main assembly A as seen from outside in the driving side. Part (b) of  FIG.  21    is a perspective view in the state shown in part (a) of  FIG.  21   .  FIG.  22    is an illustration of details of the neighborhood of the coupling member  86  at the time when the mounting of the process cartridge B to the apparatus main assembly A is completed. In  FIG.  22   , the apparatus main assembly A is shown as having a drive head  14  as the main assembly side engaging portion, a coupling guide  300   b  of the holder  300 , and the guiding member  12 , and the other parts are members of the process cartridge B. 
     In (a 1 ) of the  FIG.  22   , the process cartridge B is in the mounting completed position, and the coupling member  86  is inclined (pivoted). In (a 2 ) of  FIG.  22   , the process cartridge B is in the mounting completed position, and the axis L 2  of the coupling member  86  is substantially coaxial with the axis L 3  of the drive head  14  as the main assembly side engaging portion. Part (a 3 ) of  FIG.  22   , is an illustration of a relationship between the coupling member  86  and the coupling guide  300   b  at the time when the coupling member  86  is inclined (pivoted). Parts (b 1 ) to (b 3 ) of  FIG.  22    are sectional views taken along lines S 10 -S 10  of (a 1 ) to (a 3 ) of  FIG.  22   , respectively. 
     As shown in  FIG.  19   , the guiding member  12  as the apparatus main assembly A guiding mechanism is provided with pulling spring  356  as an urging member (elastic member). The pulling spring  356  is rotatably supported on a rotational shaft  320   c  of the guiding member  12 , and the position thereof is limited by stoppers  12   d  and  12   e . An operating portion  356   a  of the pulling spring  356  is urged in the direction of an arrow J in  FIG.  19   . 
     As shown in  FIG.  19   , when the process cartridge B is mounted to the apparatus main assembly A, it is inserted so that a first arcuate portion  76   d  of the process cartridge B moves along the first guiding member  12   a , and a rotation stopper boss  71   c  of the process cartridge B moves along the second guiding member  12   b . The first arcuate portion  76   d  of the process cartridge contacts the guide groove of the main assembly side, and at this time, the coupling member  86  is inclined toward the downstream of the mounting direction (X2 direction) by the torsion coil spring  91  as the urging member (elastic member). Here, the coupling member  86  is covered by the first arcuate portion  76   d  of the bearing member  76 . By this, the process cartridge B can be inserted to a neighborhood of the mounting completed position in the state, without interference with any parts of the apparatus main assembly A in the insertion path for the process cartridge B. 
     As shown in  FIG.  20   , when the process cartridge B is further inserted in the arrow X2 direction in the Figure, the spring receiving portion  76   e  of the process cartridge B is brought into contact to the operating portion  356   a  of the pulling spring  356 . By this, the operating portion  356   a  elastically deforms in an arrow H direction in the Figure. 
     Thereafter, the process cartridge B is mounted to a predetermined position (mounting completed position) ( FIG.  21   ). At this time, the first arcuate portion  76   d  of the process cartridge B contacts the first guiding member  12   a  of the guiding member  12 , and the leading end portion  76   f  with respect to the mounting direction contacts to the mounting end portion  12   c . Similarly, a rotation stopper boss  71   c  of the process cartridge B contacts to a positioning surface  12   h  of the guiding member  12  as the guiding mechanism. In this manner, the position of the process cartridge B relative to the apparatus main assembly A is determined. 
     At this time, the operating portion  356   a  of the pulling spring  356  presses the spring receiving portion  76   e  of the process cartridge B in the arrow J direction in the Figure to assure the contact between the first arcuate portion  76   d  and the first guiding member  12   a  and the contact between the leading end portion  76   f  and the mounting end portion  12   c . By this, the process cartridge B is correctly positioned relative to the apparatus main assembly A. 
     When the process cartridge B is mounted to the apparatus main assembly A, the coupling member  86  is engaged with the drive head  14  as the main assembly side engaging portion ( FIG.  5   ) as described hereinbefore, so that the mounting of the process cartridge B to the main assembly is completed. 
     As shown in (a 1 ) and (b 1 ) of  FIG.  22   , even when the mounting of the process cartridge B is completed, the coupling member  86  tends to incline (pivot) in the mounting direction (X2 direction) by the torsion coil spring  91 . In other words, even after the completion of the mounting, the torsion coil spring  91  continues to apply the urging force to the coupling member  86  (substantially toward the downstream with respect to the cartridge mounting direction). At this time, the interconnecting portion  86   g  contact the guide portion  300   b   2  of coupling guide  300   b  so that the inclination (pivoting) of the coupling member  86  is limited. By limiting the inclination amount of the coupling member  86 , the claw portions  86   d   1  and  86   d   2  simultaneously contact the drive pin  14   b  of the drive head  14 . More particularly, the claw portions are disposed at substantially point symmetry positions about the rotation axis of the coupling member. When the rotational force is transmitted to the coupling member  86  in this state, the axis L 2  of the coupling member  86  is substantially aligned with the axis L 3  of the drive head  14  by a couple of forces and the contact between the spherical surface portion  14   c  and the conical portion  86   f , as shown in (a 2 ) and (b 2 ) of  FIG.  22   . And, the above-described gap S is provided between the interconnecting portion  86   g  and the guide portion  300   b   2 , so that the coupling member  86  can be rotated stably. 
     When the inclination (pivoting) of the coupling member  86  is not limited, one of the claw portions  86   d   1  and  86   d   2  constituting the pair may not contact the drive pin  14   b . In such a case, the above-described couple of forces is not supplied with the result of incapability of aligning the axis L 2  of the coupling member  86  with the axis L 3  of the drive head  14 . 
     The coupling guide  300   b   1  does not interfere with the coupling member  86  in the mounting and demounting process of the process cartridge B even when the coupling member  86  is in a inclined (pivoted) state. To accomplish this, the coupling guide  300   b  is provided in a non-driving side of the free end portion  86   a  ((a 3 ) and (b 3 ) of  FIG.  22   ). The cut-away portion  76   k  of the bearing member  76  is further recessed to the non-driving side of the guide portion  300   b   2  so as to avoid the interference with the guide portion  300   b   2 . In addition, the width Z 11  of the cut-away portion  76   k  of the bearing member  76  measured in the direction perpendicular to the line S 10 -S 10  is larger than the width Z 14  of the coupling guide  300   b . By this, the size of the cartridge can be reduced while suppressing interference between the coupling guide and the cartridge. 
     In this embodiment, the inclination (pivoting) of the coupling member  86  by the torsion coil spring  91  is limited by the coupling guide  300   b . However, as described above, the inclination (pivoting) of the coupling member  86  may be effected by another means other than the torsion coil spring  91 . For example, when the coupling member  86  inclines by the weight thereof, the coupling guide  300   b  may be disposed at a lower side. As described above, the coupling guide  300   b  may be provided at a position where the inclination (pivoting) of the coupling member  86  is limited in the mounting of the process cartridge B. 
     10. Engagement and Disengagement of Coupling in Dismounting Operation of Process Cartridge. 
     Referring to  FIG.  24   , the dismounting of the process cartridge B from the apparatus main assembly A from the mounting completed position of the process cartridge B while the coupling member  86  is disengaging from the drive head  14  as the main assembly side engaging portion will be described. 
     The description will be made as to an example of this embodiment, in which the claw portions  86   d   1  and  86   d   2  of the coupling member  86  are in the upstream and downstream positions, respectively, with respect to the dismounting direction, as shown in  FIG.  24   . In this embodiment, in this state, the phase relation between the hole portion  86   b  penetrated by the pin  88  and the claw portions  86   d   1  and  86   d   2  is such that the axis of the pin  88  is substantially perpendicular to the dismounting direction (X3 direction). Part (a 1 ) of  FIG.  24    shows a state from which the disengagement of the coupling member  86  from the main assembly A occurs at the time of the dismounting of the process cartridge B from the apparatus main assembly A. Parts (a 1 ) to (a 4 ) of  FIG.  24    are perspective views as seen from an outside in the driving side, parts (b 1 ) to (b 4 ) of  FIG.  24    are sectional views taken along lines (a 1 ) to (a 4 ) of  FIG.  24   , respectively. In  FIG.  24   , similar to  FIG.  22   , the apparatus main assembly A is shown as having a drive head  14  as the main assembly side engaging portion, a coupling guide  300   b  of the holder  300 , and the guiding member  320 , and the other parts are members of the process cartridge B. 
     The process cartridge B is moved in the dismounting direction (X3 direction) from the state shown in parts (a 1 ) and (b 1 ) in which the coupling member  86  is engaged with the drive head  14 . Then, as shown in (a 2 ) and (b 2 ) of  FIG.  24   , the (axis L 2  of) the coupling member  86  is inclined (pivoted) relative to the axis L 1  and in the axis L 3 , while the process cartridge B move in the dismounting direction (X3 direction). At this time, the amount of the inclination (pivoting) of the coupling member  86  is determined by the contact of the free end portion  86   a  to the parts of the drive head  14  (the drive shaft  14   a , the drive pin  14   b , the spherical surface portion  14   c  and the free end portion  14   d ). 
     When the process cartridge B is further moved in the dismounting direction (X3 direction), the coupling member  86  is disengaged from the drive head  14  as the main assembly side engaging portion, as shown in (a 3 ) and (b 3 ) of  FIG.  24   . The coupling member  86  is urged by the torsion coil spring  91  as the urging means (urging member), by which it is further inclined (pivoted). The inclination angle of the coupling member  86  urged by the torsion coil spring as the urging member is larger than the inclination angle in the direction other than the urged direction. 
     By the contact between the second inclination regulating portion  87   n  and in the interconnecting portion  86   g  the inclination (pivoting) of the coupling member  86  is limited. The maximum rotation diameter φZ 2  of the interconnecting portion  86   g  and the second inclination angle θ 2  are determined so that the coupling member  86  can incline (pivot) to such an extent that the upstream claw portion  86   d   1  with respect to the dismounting direction can be positioned in the non-driving side beyond the free end portion  14   d  of the drive head  14 . By doing so, as shown in (a 4 ) and (b 4 ) of  FIG.  24   , the process cartridge B can be dismounted from the apparatus main assembly A while the coupling member  86  is disengaging from the drive head  14  as the main assembly side engaging portion. 
     In the case that the claw portions  86   d   1  and  86   d   2  are in the phase other than that described above, the coupling member  86  circumvents the parts of the drive head  14  as the main assembly side engaging portion by the inclination (pivoting) and/or the above-described whirling, or by a combination of these motions. By the circumventing motion, the coupling member  86  can be disengaged from the drive head  14  as the main assembly side engaging portion. 
     As shown in (a 1 ) and (b 1 ) of  FIG.  23   , in the case that the axial direction of the drive pin  14   b  and the dismounting direction (X3 direction) are substantially perpendicular to each other, the inclination occurs such that the free end portion  86   b  direct away from the dismounting direction (X2 direction), so that the claw portion  86   d   1  dodges the drive pin  14   b  in the non-driving side direction. Or, when the claw portions  86   d   1  and  86   d   2  are opposed to each other interposing the dismounting direction (X3 direction) as shown in (a 2 ) and (b 2 ) of  FIG.  23   , the inclination (pivoting) occurs such that the free end portion  86   a  moves in the direction (X6 direction) parallel with the axial direction of the drive pin  14   b . By this, the claw portion  86   d   1  can dodge the drive pin  14   b  in the direction indicated by the arrow X6. In such a case, it is necessary that the free end portion  86   a  is moved to below the axis L 3  and the axis L 1 , and therefore, the position of the lower surface  76   k   1  of the bearing member  76  is determined as described above, and the direction of the urging force of the torsion coil spring  91  is determined so that the free end portion  86   a  is directed downward. Here, the lower, below and downward are not necessarily limited to those on the basis of the direction of gravity. More particularly, it will suffice if the free end portion  86   a  is movable in the direction necessary for the claw portion  86   d   1  placed in the downstream side with respect to the mounting direction (upstream side with respect to the dismounting direction) to dodge the drive pin  14   b . Therefore, in the case that the rotational moving direction R of the drum  62  is opposite to that of this embodiment, the claw portion placed in the downstream side with respect to the mounting direction is in the upper side, and therefore, the direction in which the free end portion  86   a  is to move is upward. Therefore, in the case that the claw portions  86   d   1  and  86   d   2  are placed in the upper and lower positions across the mounting direction X2 of the coupling member  86 , it is preferable that the free end portion  86   a  is movable toward the claw portion with which the direction of the rotational force received from the drive pin  14   b  is codirectional with the mounting direction. In the two examples shown in  FIG.  23   , the inclination (pivoting) angle required before the release of the coupling member  86  from the drive head  14  as the main assembly side engaging portion may be smaller than the second inclination angle θ 2  shown in  FIG.  24   . In this embodiment, in the case shown in (a 2 ) and (b 2 ) of  FIG.  23   , the phase relation between the hole portion  86   b  of the coupling member  86  and the claw portions  86   d   1  and  86   d   2  is determined such that the inclination (pivoting) angle is the first inclination angle θ 1 . Part (b 1 ) of  FIG.  23    is a sectional view taking along a line S 11 -S 11  of (a 1 ) of  FIG.  23   . Part (b 2 ) of  FIG.  23    is a sectional view taking along a line S 11 -S 11  of (a 2 ) of  FIG.  23   . 
     Dimensions of the parts in this embodiment will be described. 
     As shown in  FIG.  6   , the diameter of the free end portion  86   a  is φZ 1 , the diameter of the interconnecting portion  86   g  is φZ 2 , the sphere diameter of the substantially spherical connecting portion  86   c  is φZ 3 , and rotation diameters of the claw portions  86   d   1  and  86   d   2  are φZ 4 . In addition, the diameter of the spherical of the free end of the drive head  14  as the main assembly side engaging portion is SφZ 7 , and the length of the drive pin  14   b  is Z 5 . Furthermore, as shown in (b 1 ) and (b 2 ) of  FIG.  15   , the inclinable (pivotable) amount (second inclination angle) of the coupling member  86  about the axis of the pin  88  is θ 2 , and the inclinable (pivotable) amount (first inclination angle) thereof about the axis perpendicular to the axis of the pin  88  is θ 1 . The gap between the interconnecting portion  86   g  and the guide portion  300   b   2  at the time when the axis L 2  and the axis L 3  are substantially coaxial is S. 
     In this embodiment, φZ 1 =10 mm, φZ 2 =5 mm, φZ 3 =11 mm, φZ 4 =7 mm, Z 5 =8.6 mm, SφZ 7 =6 mm, θ 1 =30°, θ 2 =40° and S=0.15 mm. 
     These dimensions are examples and are not restrictive to the present invention, if the similar operations are possible. More specifically, it will suffice if θ 1  and θ 2  are not less than approx. 20° and not more than approx. 60°. Preferably, they are not less than 25° and not more than 45°. Further preferably, θ 1 &lt;θ 2  is satisfied, and θ 1  this not less than approx. 20° and not more than approx. 35°, and θ 2  is not less than approx. 30° and not more than approx. 60°. The difference between θ 1  and θ 2  is not less than approx. 3° and not more than approx. 20°, and preferably, it is not less than approx. 5° and not more than approx. 15°. It will be considered to design the angles θ 1  and θ 2  such that as shown in  FIG.  25   , when the cartridge B is mounted, the leading portion (which will be described hereinafter) is positioned in the non-driving side beyond the free end portion  14   d  of the drive head  14  and in the driving side beyond the guide portion  300   b   2 . With such design, the coupling  86  can be properly engaged with the drive head  14 . The free end portion is the leading end portion  86   d   11  of the claw portion  86   d   1  when the inclination angle of the coupling member  86  is the second inclination angle θ 2 , and it is the standing-by portion  86   k   1  wherein the inclination angle of the coupling member  86  is the first inclination angle θ 1 . Because the standing-by portion  86   k   1  is closer to the rotation axis C than the leading end portion  86   d   11 , and therefore, if first inclination angle θ 1 &lt;second inclination angle θ 2  is satisfied, the position of the leading end portion in the axis L 1  direction when the coupling member  86  is inclined can be made the similar. By this, it is unnecessary to widen the gap between the drive head  14  and the guide portion  300   b   2 , so that the apparatus main assembly A and/or the cartridge B can be downsized. 
     By satisfying φZ 1 &lt;φZ 3 , the assembling is easy as in this embodiment. Furthermore, by satisfying φZ 1 &lt;φZ 10 &lt;φZ 3  taking into account the minimum diameter φZ 10  of the conical portion  87   k  as the disengagement prevention portion (overhang portion, disengagement preventing portion), the position of the coupling member  86  in the driving side flange unit U 2  can be determined with high precision. 
     According to this embodiment, the conventional cartridge which can be dismounted to the outside of the main assembly after being moved in the predetermined direction substantially perpendicular to the rotational axis of the main assembly side engaging portion can be further improved. 
     Embodiment 2 
     This embodiment will be described in conjunction with the accompanying drawings. In this embodiment, the structures of the parts other than a free end portion  286   a  of a coupling member  286 , a drive head  214  and a coupling guide  400   b  are similar to those of the first embodiment, and therefore, the description of such other parts is omitted by assigning the same reference numerals as in the first embodiment. Even if the same reference numerals are assigned, the parts may be partly modified so as to match the structure of this embodiment. 
       FIG.  26    is an illustration of the coupling member  286  and the drive head  214  as the main assembly side engaging portion. Part (a) of  FIG.  26    is a side view, part (b) of  FIG.  26    is a perspective view, part (c) of  FIG.  26    is a sectional view taken along a line S 21 -S 21  of part (a) of  FIG.  26   . Part (d) of  FIG.  26    is a sectional view taken along a line S 22 -S 22  of part (a) of  FIG.  26   , the line S 22 -S 22  being perpendicular to a receiving portion  286   e   1  and passing through the center of a drive pin  214   b  as the applying portion. 
     As shown in  FIG.  26   , the configurations of the claw portions  286   d   1  and  286   d   2  of the coupling member  286  is different from those of the first embodiment. The claw portions  286   d   1 ,  286   d   2  have respective flat internal wall surfaces  286   s   1 ,  286   s   2  facing toward the axis L 2 , and a widths Z 21  of the receiving portions  286   e   1 ,  286   e   2  in the diametrical direction is larger than those of Embodiment 1. More particularly, as compared with Embodiment 1, the widths of the claw portions  286   d   1 ,  286   d   2  in the diametrical direction are larger. A diameter φZ 22  of an inscribed circle of the internal wall surfaces  286   s   1 ,  286   s   2  about the axis L 2  is larger than the diameter φZ 7  of the driving shaft  214   a  of the drive head  214 . Here, an amount of overlapping between the drive pins  214   b   1 ,  214   b   2  and the receiving portions  286   e   1 ,  286   e   2  in part (d) of  FIG.  26    in the axial direction of the drive pins  214   b   1 ,  214   b   2  (direction perpendicular to the axis L 2  (L 3 )) is called engagement amount Z 23 . 
     On the other hand, the drive head  214  is provided at a base portion of the drive pin  214   b  with a receiving spherical surface portion  214   c  and a recess  214   e  recessed from the drive shaft  214   a  in a downstream side of the drive pin  214   b  with respect to the rotational moving direction (R direction). 
     Referring to  FIG.  27   , engaging and disengaging operations between the coupling member  286  and the drive head  214  when the process cartridge B is mounted to and dismounted from the apparatus main assembly A will be described in detail. The operation peculiar to this embodiment will be described. This is when the phase of the drive pins  214   b   1  and  214   b   2  is deviated from the dismounting direction (X3 direction) of the cartridge B by a predetermined amount θ 4 , for example by θ 4 =60° which case will be described. 
       FIG.  27    is an illustration of the operation of the coupling member  286  when the cartridge B is dismounted from the apparatus main assembly A. Parts (a 1 ) to (a 4 ) of  FIG.  27    are views as seen from the outside in the driving side of the main assembly A, illustrating the dismounting of the process cartridge B from the apparatus main assembly A, in this order. Parts (b 1 ) to (b 4 ) of  FIG.  27    are sectional views taken along lines S 23 -S 23  of (a 1 ) to (a 4 ) of  FIG.  27    seen from the bottom. For better illustration, the coupling member  286 , the drive head  214  and the pin  88  are not sectional views. 
     As shown in (a 1 ) of  FIG.  27   , when the process cartridge B is dismounted from the apparatus main assembly A, the cartridge B is first in the mounting completed position in the apparatus main assembly A in which the coupling member  286  is engaged with the drive head  214 . In many cases, the process cartridge B is dismounted from the apparatus main assembly A after a series of image forming operations it is completed. At this time, the receiving portions  286   e   1  and  286   e   2  of the coupling member are contacted to the drive pins  214   b   1  and  214   b   2 , respectively. 
     From the state, the cartridge B is moved in the dismounting direction (X3 direction the, and shown in (a 2 ) and (b 2 ) of  FIG.  27   . The cartridge B is moved in the dismounting direction (X3 direction) while the axis L 2  of the coupling member  286  is inclining relative to the axis L 1  of the driving side flange  87  and the axis L 3  of the drive head  214 . At this time, the claw portion  286   d   1  (receiving portion  286   e   1 ) in the downstream side of the drive pin  214   b   1  with respect to the dismounting direction (X3 direction) keeps in contact with the drive pin  214   b   1 . 
     The cartridge B is further moved in the dismounting direction (X3 direction), as shown in (a 3 ) and (b 3 ) of  FIG.  27   . Then, the axis L 2  further inclines (pivots) so that a first inclination-regulated portions  286   p   1  and  286   p   2  (unshown) and the pin  88  as the first inclination regulating portion contact to each other, or the second inclination regulating portion  87   n  and the interconnecting portion  286   g  as the second inclination-regulated portion contact to each other, similarly to the first embodiment. By this, the inclination (pivoting) of the coupling member  286  is limited. In the case of the phase) (θ=60° of the drive pin  214   b  and the claw portions  286   d   1  and  286   d   2  shown in  FIG.  27   , the claw portion  286   d   1  (receiving portion  286   e   1 ) may not move to the non-driving side of the drive pin  214   b  but may keep the contact state. This is because the movement distances of the claw portions  286   d   1  and  286   d   2  toward the non-driving side by the inclination (pivoting) of the axis L 2  is small. 
     At this time, since the drive head  214  is provided with the cut-away portion  214   e , the coupling member  286  inclines (pivots) in the direction of an arrow X5 so that the claw portions  286   d   1  and  286   d   2  move along the drive pins  214   b  and  214   b   2 . 
     As shown in (a 4 ) and (b 4 ) of  FIG.  27   , the coupling member  286  further inclines (pivots) in the direction of the arrow X5 by the claw portion  286   d   2  entering the cut-away portion  214   e . By the inclination (pivoting) of the coupling member  286 , the contact between the claw portion  286   d   1  and the drive pin  214   b   1  is released in the direction of the arrow X5. By this, the process cartridge B can be dismounted from the apparatus main assembly A. 
     In this embodiment, as compared with Embodiment 1, the widths Z 21  of the receiving portions  286   e   1  and  286   e   2  are larger. More specifically, the width of the base portion is approx. 1.5 mm With such a structure, the engagement amount Z 23  (part (d) of  FIG.  26   ) between the drive pin  214   b   1 ,  214   b   2  and in the receiving portion  286   e   1 ,  286   e   2  in the axial direction of the drive pin  214   b  is larger than that in Embodiment 1. By this, the engagement between the pair of applying portions and the pair of receiving portions is assured so that stabilized transmission is accomplished irrespective of variation of the part accuracy or the like. By increasing the width of the base portion of the receiving portion, the driving force transmission can be stabilized, but if it is too large, the interference with the drive head may occur with the result of adverse affect. Therefore, it is preferable that in an imaginary flat plane perpendicular to the rotational axis of the coupling member and including the receiving portion for receiving the driving force from the engaging portion, a angle between the rotational axis and the line connecting the end portions of the projections is not less than approx. 10° and not more than approx. 30°. Taking into account the rigidity for the reception of the drive, the width of the base portion is 1.0 mm or larger. 
     The cut-away portion  214   e  is desired to be enough to permit disengagement between the coupling member  286  and the drive head  214  even when the engagement amount Z 23  is larger than the gap between the inner diameter φZ 24  of the claw portion and the diameter φZ 27  of the cylindrical portion of the drive head  214 . Therefore, it is provided so as to permit large inclination (pivoting) of the coupling member  86  in the direction of the arrow X5. Here, the large inclination means that the claw portions  286   d   1  and  286   d   2  cam move toward the drive pins  214   b   1  and  214   b   2  through a distance larger than the engagement amount Z 23 . 
     Referring to  FIG.  28   , the structure of the coupling guide  400   b  in this embodiment will be described. The structure of the coupling guide  400   b  is similar to that of Embodiment 1, but the gap S 2  between the interconnecting portion  286   g  of the coupling member  286  and the coupling guide  400   b  is different from that of first embodiment. 
       FIG.  28    is an illustration of the coupling guide  400   b  and (a 1 ) (b 1 ) of  FIG.  28    shows the state in which the cartridge B is mounted to the apparatus main assembly A, and the axis L 2  of the coupling member  286  keeps inclined (pivoted). Parts (a 2 ) and (b 2 ) of  FIG.  28    shows the state in which the axis L 2  is aligned with the axis L 1  and the axis L 3 . Part (b 1 ) of  FIG.  28    is a sectional view taking along a line S 24 -S 24  of (a 1 ) of  FIG.  28   . Part (b 2 ) of  FIG.  28    is a sectional view taking along a line S 24 -S 24  of (a 2 ) of  FIG.  28   . 
     As shown in (a 1 ) and (b 1 ) of  FIG.  28   , the coupling guide  400   b  is capable of limiting the inclination (pivoting) of the coupling member  286  so that the engagement between the drive pin  214   b  and the claw portion  286   d   1  is kept even when the coupling member  286  is inclined (pivoted). In this embodiment, as described hereinbefore, the engagement amount Z 23  is larger than that in Embodiment 1. In this embodiment, the gap S 2  in (b 2 ) of  FIG.  28    is larger than the gap S in Embodiment 1 ((b 2 ) of  FIG.  22   ). Despite such conditions, the engagement between the drive pin  214   b   1  and the receiving portion  286   e   1  can be kept to properly transmit the rotation even when the inclination (pivoting) of the coupling member  86  increases. In this manner, the gap S 2  can be made larger than in Embodiment 1, and therefore, the dimensional accuracy of the interconnecting portion  286   g  and/or the guide portion  400   b   2  can be eased. 
     As described above, the engagement amount Z 23  between the drive pin  214   b   1 ,  214   b   2  and in the claw portion  286   d   1 ,  286   d   2  is increased, and the drive head  214  is provided with the cut-away portion  214   e . By doing so, when the cartridge B is dismounted from the apparatus main assembly A, the engagement between the coupling member  286  and the drive head  214  can be released. In addition, with the structure of this embodiment, the gap S 2  between the coupling guide  400   b  and the interconnecting portion  286   g  can be increased as compared with Embodiment 1, by which the required part accuracy can be eased. 
     Embodiment 3 
     A third embodiment of the present invention will be described.  FIG.  29    is an illustration of a coupling member  386  and a drive head  314  as the main assembly side engaging portion.  FIG.  30    is an illustration of a R configuration portion  386   g   1  and shows a state in which the cartridge B is mounted to the apparatus main assembly A.  FIG.  31    is an illustration of a bearing member  387  and the coupling member  386  and is a perspective view and a sectional view. 
     The coupling member  386  is provided with lightening portions  386   c   2 - 386   c   9  in a connecting portion  386   c  as is different from Embodiment 1 and Embodiment 2. A diameter of an interconnecting portion  386   g  is small, and a thickness defined by a spring receiving portion  386   h  and a receiving surface  386   f  is small. By this, the material can be saved. 
     In providing the lightening portions  386   c   2 - 386   c   9 , it is preferable that the spherical  386   c   1  remains evenly along the circumferential direction. In this embodiment, the connecting portion  386   c  is construct in such that the void of the spherical portion  386   c   1  provided by the lightening portions  386   c   2 - 386   c   9  and the hole portion  386   b  is less than continuously 90°. The spherical portion may be substantially spherical in consideration of the lightening and/or manufacturing variation or the like. With the above-described structure of the connecting portion  386   c , the position of the coupling member  86  in the driving side flange unit U 32  can be stabilized. Particularly, the position of the coupling member can be stabilized at the position of the line S 14 -S 14  supported by the accommodating portion  87   i  and at the position opposing to the conical portion  87   k  and the base portion  89   a , as shown in part (c) of  FIG.  29   . 
     An arcuate surface portion  386   q   1  and an arcuate surface portion  386   q   2  have diameters different from each other. 
     As shown in  FIG.  30   , a R (rounded) configuration  386   g   1  is provided between the interconnecting portion  386   g  and the spring receiving portion  386   h . As described hereinbefore, in the driving side flange unit U 32 , there is provided a play for permitting small amount of movement of the coupling member  386  in the axis L 1  direction. When the coupling member  386   a  shifts to the non-driving side within the range of the play, the engagement amount Z 38  between the drive pin  314   b  and the claw portion  386   d   1 ,  386   d   2  in the axis L 1  direction decreases. Here, the engagement amount Z 38  is a distance in the axis L 3  direction between the center point of the arcuate configuration of the drive pin  314   b  and the free end of the claw portion  386   d   1 . In addition, when the coupling member  386  inclines to the extent that the interconnecting portion  386   g  and a guide portion  330   b   2  of the coupling guide  330   b  contact to each other, the engagement amount Z 38  between the drive pin  314   b  and in the claw portion  386   d   1 ,  386   d   2  decreases with the possible result of adverse affect to the driving force transmission. However, by the provision of the R configuration portion  386   g   1 , the free end of the guide portion  330   b   2  of the coupling guide  330   b  is contacted by the R configuration portion  386   g   1  when the coupling member  386  shifts toward the non-driving side. By this, as compared with the case in which the interconnecting portion  86   g  contacts to the guide portion  300   b   2  as in Embodiment 1, the inclination of the coupling member  386  can be reduced. Therefore, the provision of the R configuration portion  386   g   1  is effective to prevent simultaneous occurrences of the decrease of the engagement amount Z 38  attributable to the shifting of the coupling member  386  toward the non-driving side and the reduction of the engagement amount Z 38  attributable to the inclination of the coupling member  386 . The R configuration portion  386   g   1  is not limited to the arcuate configuration, but may be a conical surface configuration with the similar effects. 
     As shown in  FIG.  29   , in this embodiment, the claw portions  386   d   1  and  386   d   2  have flat surface at the free end portions, thus increasing the thickness in the circumferential direction, by which the deformation of the claw portions  386   d   1  and  386   d   2  during the drive transmission is reduced. In addition, in order to define the portion pressed by the torsion coil spring  91 , the spring receiving portion  386   h  is provided with a spring receiving groove  386   h   1  (part (d) of  FIG.  30   , too). The portion contacting the second arm  91   b  of the spring  91  is regulated, and by applying a lubricant there, the sliding between the second arm  91   b  and the coupling member  386  it is effected with grease always in existing therebetween, and therefore, the scraping of these members and the sliding noise can be reduced. The coupling member  386  is made of metal, and the torsion coil spring  91  is made of metal, too. In the state that the coupling member  386  is being rotated by the driving force received from the main assembly side engaging portion  314 , the torsion coil spring  91  continues to apply the urging force to the coupling member. Therefore, during the image forming operation, the sliding occurs between metal members, and in order to reduce the influence thereof, it is preferable to provide lubricant at least between the coupling member  386  and the torsion coil spring  91 . 
     On the other hand, as shown in part (b) of  FIG.  29   , the drive pin  314   b  of the main assembly side engaging portion  314  is not necessarily a circular column configuration member. The diameter sφZ 36  of the spherical surface portion  314   c  is larger than the diameter sφZ 6  of the spherical surface portion  14   c  and the diameter φZ 37  of the driving shaft  314   a  in Embodiment 1, because it is contacted to a receiving surface  386   f  which is thinner than in Embodiment 1. For the purpose of sliding engagement (and disengagement) with the coupling member  386 , a taper  314   e   1  is provided at a stepped portion minute between the cut-away portion  314   e  and the driving shaft  314   a.    
     The diameter of the free end of the guide portion  330   b   2  of the coupling guide  330   b  shown in  FIG.  30    is smaller than that of Embodiment 1 because the diameter of the interconnecting portion  386   g  is smaller than that of Embodiment 1. 
     Referring to  FIG.  31   , the bearing member  376  will be described in detail. As shown in  FIG.  31    a width Z 32  of a cut-away portion  376   k  of the bearing member  376  is larger than the diameter φZ 31  of the free end portion  386   a , so that the free end portion  386   a  directs downward relative to the mounting direction X2 and axis L 1 , similarly to Embodiment 1. On the other hand, a plate-like portion  376   h  is provided at the position closer to the driving side than in Embodiment 1. Therefore, when the coupling member  386  inclines, the outsidemost circumference (φZ 31  part) of the free end portion  386   a  contacts a lower surface  376   k   1  of the cut-away portion  376   k . By this, the downward inclination of the coupling member  386  is limited irrespective of the inclination angle of the coupling member  386 , and therefore, the engagement with the main assembly side engaging portion  314   b  is further stabilized. (in Embodiment 1, the conical spring receiving portion  87   h  contacts the lower surface  76   k   1 , and therefore, the amount of the downward inclination of the coupling member  86  is different depending on the inclination angle of the coupling member  86 ). 
     A spring hook portion  376   g  comprises a retaining portion  376   g   1 , an insertion opening  376   g   2  and a supporting portion  376   g   3 . The insertion opening  376   g   2  and the supporting portion  376   g   3  are connected with each other by a tapered portion  376   g   4  so that the spring  91  can be smoothly slipped in the direction of an arrow X10. The most outer diameter Z 33  of the retaining portion  376   g   1  and the insertion opening  376   g   2  and the most outer diameter of the supporting portion  376   g   3  are smaller than the inner diameter φZ 35  of the coil portion  91   c  of the spring  91 . With the above-described structure of the spring hook portion  376   g , the coil portion  91   c  can be easily slipped around the spring hook portion  376   g , and the movement of the coil portion  91   c  in the direction of disengagement from the retaining portion  376   g   1  by the supporting portion  376   g   3  can be suppressed. By this, the possibility of the disengagement of the spring  91  from the spring hook portion  376   g  can be reduced. The spring hook portion  376   g  does not project beyond the first projected portion  376   j  outwardly (driving side), so that the possibility of the damage of the spring hook portion  376   g  during the transportation is reduced. 
     In this embodiment, it is preferable that the retaining portion  376   g   1  is disposed in the side opposite from the spring hook portion  376   g  across the coupling member  386  (lower left side in part (a) of  FIG.  31   ). 
     To described briefly, a reaction force received by the torsion coil spring  91  (a resultant force of a force F 91   a  received by the first arm  91   a  and a force F 91   b  received by the second arm  91   b ) directs toward the coupling member  386  side (upper right side in part (a) of  FIG.  31   ). By this, the coil portion  91   c  shifts toward the coupling member  386 . Therefore, the above-described position of the retaining portion  376   g  is effective to assure that the mounting property of the torsion coil spring  91  the prevention of the disengagement thereof. Furthermore, in this embodiment, as shown in part (c) of  FIG.  31   , when the coupling member  386  is inclined so as to be close to the coil portion  91   c  side, the first arm and the second arm are substantially parallel with each other. Therefore, the force F 91   a  and the force F 91   b  are canceled, and therefore, the reaction force received by the torsion coil spring  91  is reduced. In this manner, the force F 91  does not direct toward the retaining portion  376   g   1 , by which the possibility of the disengagement of the torsion coil spring  91  from the spring hook portion  376   g  is reduced. 
     The bearing member  376  is provided with a contact prevention rib  376   j   5  and a contact prevention surface  376   j   2  in order to prevent contact of the coupling member  386  to the coil portion  91   c . By this, even when the coupling member  386  inclines close to the coil portion  91   c , the coupling member  386  contacts to the contact prevention rib  376   j   5 , the contact prevention surface  376   j   2 , so that the contact of the free end portion  386   a  to the coil portion  91   c  is prevented. By this, the possibility of the disengagement of the coil portion  91   c  from the retaining portion  376   g   1  can be suppressed. 
     Furthermore, radially inside of the first projected portion  376   j , a space  376   j   4  is provided to permit movement of the second arm of the spring  91 . Here, the second arm  91   b  has such a length that an arm portion  91   b   1  of the second arm  91   b  can be always contacted to the spring receiving portion  386   h  ( FIG.  29   ) of the coupling member  386 . By doing so, the contact of the free end  91   b   2  of the second arm to the spring receiving portion  386   h  can be prevented. 
     In this embodiment, the disengagement prevention of the torsion coil spring  91  it is effected by the configuration of the spring hook portion  376   g , but may be effected using application of silicon bond or hot melt. Alternatively, another resin material member may be used for the prevention of the disengagement. 
     Embodiment 4 
     Referring to  FIG.  32   , another structure of driving side flange unit and a bearing member supporting it in this embodiment will be described. In this embodiment, the other parts of other than the driving side flange unit and the bearing member are the same as in the first embodiment, and the descriptions thereof is omitted by assigning that the same reference numerals. Even if the same reference numerals are assigned, the parts may be partly modified so as to match the structure of this embodiment. 
     As shown in  FIG.  32   , in this embodiment, a first projected portion  476   j  of the bearing member  476  is divided into upper and lower parts. The assembling property of the torsion coil spring  91  relative to the spring hook portion  476   g  using a tool or assembling device is improved because the neighborhood structure parts are less. In Embodiment 1, the supporting portion  76   a  as the second projected portion is projected from the plate-like portion  76   h  toward the non-driving side, it is possible that a supporting portion  476   a  is provided inside a hollow portion  476   i , as shown in parts (c) and (d) of  FIG.  32   . In such a case, the supported portion  487   d  of the driving side flange  487  is preferably provided on a second cylindrical portion  487   h  as long as the inclination (pivoting) of the coupling member  86  is not influenced. In this case, there is no second projected portion (supporting portion  76   a ) in the annular groove portion  87   p , and therefore, it is unnecessary for the driving side flange  487  is provided with an annular groove portion  487   p . Or, even if an annular groove portion  487   p  is provided from the standpoint of convenience in the resin material molding, it is possible that a first cylindrical portion  487   j  and the second cylindrical portion  487   h  are connected using rib configuration portions  487   p   1 - 487   p   4  to suppress the formation of the time when the drive is transmitted to the driving side flange  487 . 
     Embodiment 5 
     Referring to  FIG.  33   , a further structure of driving side flange unit and a bearing member supporting it in this embodiment will be described. In this embodiment, the other parts of other than the driving side flange unit and the bearing member are the same as in the first embodiment, and the descriptions thereof is omitted by assigning that the same reference numerals. Even if the same reference numerals are assigned, the parts may be partly modified so as to match the structure of this embodiment. 
     As shown in  FIG.  33   , a cut-away portion  576   k  of the bearing member  576  in this embodiment is different from that in Embodiment 1. In Embodiment 1, the cut-away portion  76   k  has been in the form of a groove recessing from the plate-like portion  76   h  toward the non-driving side and extending in parallel with the mounting direction X2. The cut-away portion  576   k  of the bearing member  576  is common with that of Embodiment 1 in that it is recessed from the plate-like portion  576   h  toward the non-driving side, but the groove-like configuration is not inevitable. It will suffice if the recess from the plate-like portion  576   h  is enough to provide a space for permitting inclination of the coupling member  86 , and a lower surface  576   k   1  is capable of limiting the position of the coupling member  86  (free end portion  86   a ) in the vertical direction. 
     In Embodiment 1, the supported portion  87   d  is provided on an inner circumference of the first cylindrical portion  87   j  of the driving side flange  87 , but in this embodiment, the outer peripheral surface of the second cylindrical portion  587   h  is used as the supported portion  587   d . In one of the bearing members  576 , a supporting portion  576   a  as the second projected portion enters a groove portion  587   p  to support the supported portion  587   d . The second cylindrical portion  587   h  is projected more toward the driving side than the first cylindrical portion  587   j , and therefore, by the provision of the supported portion  587   d  on the second cylindrical portion  587 , the supporting length in the axis L 1  direction can be increased as compared with the case in which the supported portion is provided on the first cylindrical portion  587   j.    
     Other Embodiments 
     In the foregoing embodiments, the coupling member is accommodated in the flange unit of the photosensitive drum, but this is not inevitable, and it will suffice if the drive is received by the cartridge through the coupling member. More particularly, the structure may be that a developing roller is rotated through a coupling member. The present invention is suitably applicable to a developing cartridge not comprising a photosensitive drum in which the rotational force is transmitted from the main assembly side engaging portion to the developing roller. In such a case, the coupling member  86  transmits the rotational force to the developing roller  32  as the rotatable member in place of the photosensitive drum. 
     The present invention is applicable to the structure in which the driving force is transmitted to the photosensitive drum only. In the foregoing embodiments, the driving side flange  87  as the force receiving member is fixed to a longitudinal end portion of the drum  62  which is the rotatable member, the driving side flange  87  may be an independent part not fixed thereto. For example, it may be a gear member with which the driving force is transmitted to the drum  62  and/or to the developing roller  32  through a gear connection. 
     In the foregoing embodiments, the cartridge B is for forming monochromatic images. However, this is not inevitable. The structures and concept of the above-described embodiments are suitably applicable to a cartridge for forming multi-color images (two-color images, or full-color images, for example) using a plurality of developing means. 
     A mounting-and-demounting path of the cartridge B relative to the apparatus main assembly A may be a linear path, a combination of linear paths or curved path, and the structures of the above-described embodiments can be used in such cases. 
     INDUSTRIAL APPLICABILITY 
     The structures of the foregoing embodiments can be applied to a cartridge usable with an electrophotographic image forming apparatus and a drive transmission device for them. 
     REFERENCE NUMERALS 
     
         
         
           
               3 : laser scanner unit (exposure means, exposure device) 
               7 : transfer roller 
               9 : fixing device (fixing means) 
               12 : guiding member (guiding mechanism). 
               12   a : first guiding member 
               12   b : second guiding member 
               13 : opening and closing door 
               14 : drive head (main assembly side engaging portion) 
               14   a : drive shaft (shaft portion) 
               14   b : drive pin (applying portion) 
               20 : developing unit 
               21 : toner accommodating container 
               22 : closing member 
               23 : developing container 
               32 : developing roller (developing means, process means, rotatable member) 
               60 : cleaning unit 
               62 : photosensitive drum (photosensitive member, rotatable member) 
               64 : non-driving side flange 
               66 : charging roller (charging means, process means) 
               71 : cleaning frame 
               74 : exposure window 
               75 : coupling member 
               76 : bearing member (supporting member) 
               76   b : guide portion 
               76   d : first arcuate portion 
               76   f : second arcuate portion 
               77 : cleaning blade (removing means, process means) 
               78 : drum shaft 
               86 : coupling member 
               86   a : free end portion (cartridge side engaging portion) 
               86   b   1 : transmitting portion 
               86   p   1 ,  86   p   2 : first inclination (pivoting) regulated portion 
               86  connecting portion (accommodated portion) 
               86   d   1 ,  86   d   2 : projection 
               86   e   1 ,  86   e   2 : receiving portion 
               86   f : receiving surface 
               86   g : interconnecting portion 
               86   h : spring receiving portion 
               86   k   1 ,  86   k   2 : standing-by portion 
               86   m : opening 
               86   z : recess 
               87 : driving side flange (force receiving member). 
               87   b : fixed portion 
               87   d : supported portion 
               87   e : hole portion 
               87   f : retaining portion 
               87   g : receiving portion 
               87   k : conical portion 
               87   m : opening 
               87   n : second inclination regulating portion 
               87   i : accommodating portion 
               88 : pin (shaft portion, shaft) 
               89 : closing member (regulating member) 
               90 : screw (fastening means, fixing means) 
             A: main assembly of electrophotographic image forming apparatus (apparatus main assembly) 
             B: process cartridge (cartridge) 
             T: toner (developer) 
             P: sheet (sheet material, recording material) 
             R: rotational moving direction 
             S: gap 
             U 1 : photosensitive drum unit (drum unit) 
             U 2 : driving side flange unit (flange unit) 
             L 1  you, rotational axis of electrophotographic photosensitive drum 
             L 2  rotational axis: of coupling member 
             L 3 : rotational axis of main assembly side engaging portion 
             θ 1 : inclination angle (first angle) 
             θ 2 : inclination angle (second angle)