Process cartridge, electrophotographic image forming apparatus, driving force transmission part, and electrophotographic photosensitive drum

• US 5,903,803 A
• Filed: 03/26/1996
• Issued: 05/11/1999
• Est. Priority Date: 03/27/1995
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ito, Yoshihiro, Kawai, Toshiharu, Watanabe, Kazushi
• Primary Examiner(s): Brase, Sandra L.
• Application Number:
  US08/621,941
• Time in Patent Office: 1,141 Days
• Field of Search: 399/110, 399/111, 399/116, 399/117, 399/159, 399/167, 355/200, 355/210, 355/211, 355/260
• US Class Current: 399/116
• CPC Class Codes: F16D 1/101 without axial retaining means rotating with the coupling
• CPC Class Codes: G03G 15/757 Drive mechanisms for photosensitive medium, e.g. gears
• CPC Class Codes: G03G 21/1633 using doors or covers G03G21/1638 takes precedence
• CPC Class Codes: G03G 21/1647 Mechanical connection means
• CPC Class Codes: G03G 21/186 Axial couplings
• CPC Class Codes: G03G 2221/1654 Locks and means for positioning or alignment
• CPC Class Codes: G03G 2221/1657 transmitting mechanical drive power
• CPC Class Codes: G03G 2221/183 Process cartridge

Abstract

An electrophotographic image forming apparatus for forming an image on a recording material includes an electrophotographic photosensitive drum; a charging device for charging the photosensitive drum; a developing device for developing a latent image formed on the photosensitive drum into a toner image; a transfer device for transferring the toner image onto the recording material; a fixing device for fixing the toner image on the recording material; a motor; a main assembly side gear for receiving driving force from the motor; a twisted hole formed substantially at a center of the gear, the hole having a polygonal cross-section; a twisted prism projection provided at a longitudinal end of the photosensitive drum, wherein when the main assembly side gear rotates with the hole and projection engaged with each other, rotational driving force is transmitted from the gear to the photosensitive drum through the hole and the projection with the projection being pulled into the hole; and a moving device for imparting relative movement between the hole and the projection in a longitudinal direction of the photosensitive drum.

Claims

1. An electrophotographic image forming apparatus for forming an image on a recording material, comprising:

an electrophotographic photosensitive drum;

charging means for charging said photosensitive drum;

developing means for developing a latent image formed on said photosensitive drum into a toner image;

transfer means for transferring the toner image onto the recording material;

fixing means for fixing the toner image on the recording material;

a motor;

a driving rotatable member for receiving a driving force from said motor;

a twisted hole substantially coaxial with said driving rotatable member, said hole having a polygonal cross-section;

a twisted prism projection provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said hole and projection engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said hole and said projection with said projection being pulled into said hole; and

moving means for imparting relative movement between said hole and said projection in a longitudinal direction of said photosensitive drum.

2. An apparatus according to claim 1, wherein said hole is formed in an end of a first column projected from a rotational axis of said driving rotatable member, and said projection is projected from an end of a shaft projected outwardly in a rotational direction from said photosensitive drum.

3. An apparatus according to claim 2, wherein an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C.

4. An apparatus according to claim 1 or 2, further comprising a drum gear, wherein said developing means includes a developing roller, and wherein said projection is provided at a drum gear side of said photosensitive drum, and wherein said drum gear functions to transmit the driving force to said developing roller.

5. An apparatus according to claim 4, wherein said developing means includes a developing roller, and wherein said driving rotatable member and drum gear are helical gears, said helical gears transmitting driving force to said developing roller.

6. An apparatus according to claim 1, further comprising a circular or arcuate wall extending around said projection, said wall functioning as a guide for engagement between said hole and projection.

7. An apparatus according to claim 1 or 2, wherein an outer diameter F of said shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of a drum gear of said photosensitive drum and an inner diameter of said photosensitive drum D2, satisfy:

G>

D2, and G>

F≧

C.

8. An apparatus according to claim 1 or 6, wherein an outer diameter D1 of said photosensitive drum and dedendum diameter L of said driving rotatable member satisfy:

1.0×

D1≦

L≦

5.0×

D1, approximately.

9. An apparatus according to claim 1 or 6, wherein said driving rotatable member has a module of approximately 0.4-0.7 and has a dedendum diameter L of approximately 30-150 mm, and further has 40-400 teeth.

10. An apparatus according to claim 1 or 6, wherein said hole has a substantially triangular cross-section, and said projection has a substantially triangular cross-section, and wherein corners of the triangular shapes are beveled.

11. An apparatus according to claim 1, wherein said photosensitive drum, said charging means and said developing means are contained in a process cartridge which is detachably mountable to said apparatus.

12. An apparatus according to claim 11, further comprising an openable cover for permitting mounting and demounting of said process cartridge relative to a main assembly of said apparatus, and said moving means are for moving said hole away from said projection in interrelation with opening of said cover, and are for moving said hole toward said projection in interrelation with closing of said cover;

and means for feeding the recording material.

13. A process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein said main assembly includes a motor, a driving rotatable member for receiving a driving force from said motor, and a twisted hole having a polygonal cross-section and formed substantially coaxial with said driving rotatable member, said process cartridge comprising:

an electrophotographic photosensitive drum;

process means actable on said photosensitive drum; and

a twisted polygonal prism projection provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said hole and projection engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said hole and said projection with said projection being pulled into said hole.

14. A process cartridge according to claim 13, wherein said projection is projected from an end of a shaft projected outwardly in a rotational axis direction from said photosensitive drum and said shaft functions to rotatably support said photosensitive drum in a cartridge frame.

15. A process cartridge according to claim 14, wherein said process means includes a developing roller, wherein said shaft is substantially coaxial with a helical gear, and at a side opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, and wherein said projection, helical gear, engaging portion and shaft are of integrally molded resin material, and the helical gear transmits driving force to said developing roller.

16. A process cartridge according to claims 13 or 15, further comprising a circular or arcuate wall extending around said projection, said wall functions as a guide for engagement between said hole and projection.

17. A process cartridge according to claim 15, wherein an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft, and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C.

18. A process cartridge according to claim 13 or 15, wherein said hole has a substantially triangular cross-section, and said projection has a substantially triangular cross-section, and wherein corners of the triangular shapes are beveled.

19. A process cartridge according to claim 13, further comprising a portion to be urged by a part of the main assembly by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted to the main assembly.

20. A process cartridge according to claim 13, wherein said process means includes at least one of charging means, developing means and cleaning means as a unit.

21. An electrophotographic image forming apparatus, for forming an image on a recording material, to which a process cartridge is detachably mountable, said apparatus comprising:

a motor;

a driving rotatable member for receiving a driving force from said motor;

a twisted hole substantially coaxial with said driving rotatable member, said hole having a polygonal cross-section;

means for mounting a process cartridge, the process cartridge including;

an electrophotographic photosensitive drum;

process means actable on said photosensitive drum; and

a twisted polygonal prism projection provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said hole and projection engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said hole and said projection with said projection being pulled into said hole;

moving means for imparting relative movement between said hole and said projection in a longitudinal direction of said photosensitive drum; and

means for feeding the recording material.

22. An apparatus according to claim 21, wherein a shaft of said photosensitive drum is substantially coaxial with a helical gear, and at a side opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, wherein said projection, helical gear, engaging portion and shaft are made of integrally molded resin material, and said helical gear transmits driving force to a developing roller as said process means.

23. An apparatus according to claim 21, wherein said process cartridge further comprises a portion to be urged by a part of a main assembly of said apparatus by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted to the main assembly.

24. An apparatus according to claim 21, wherein said process means includes at least one of charging means, developing means and cleaning means as a unit.

25. An apparatus according to claim 24, wherein said process cartridge further includes a drum gear, wherein said driving rotatable member and drum gear are helical gears, and wherein said helical gears transmit a driving force to a developing roller as said process means.

26. An apparatus according to claim 21, wherein a shaft is projected outwardly in a rotational axis direction from said photosensitive drum, and said shaft functions to rotatably support said photosensitive drum in a cartridge frame, and wherein an outer diameter F of the shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of a gear of said photosensitive drum and an inner diameter D2 of said photosensitive drum, satisfy:

G>

D2, and G>

F≧

C.

27. An apparatus according to claim 21, wherein an outer diameter D1 of said photosensitive drum and dedendum diameter L of said driving rotatable member satisfy:

1.0×

D1≦

L≦

5.0×

D1, approximately.

28. An apparatus according to claim 21, wherein said driving rotatable member has a module of approximately 0.4-0.7 and has a dedendum diameter L of approximately 30-150 mm, and further has 40-400 teeth.

29. An apparatus according to claim 21, further comprising an openable cover for permitting mounting and demounting of said process cartridge relative to a main assembly of said apparatus, and said moving means are for moving said hole away from said projection in interrelation with opening of said cover, and are for moving said hole toward said projection in interrelation with closing of said cover.

30. A process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein said main assembly includes a motor, a driving rotatable member for receiving driving force from said motor and a twisted hole substantially coaxial with said driving rotatable member, said hole having a substantially triangular cross-section, said process cartridge comprising:

a cartridge frame;

an electrophotographic photosensitive drum;

a developing roller for developing a latent image formed on said photosensitive drum; and

a twisted substantially triangular prism projection provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said hole and projection engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said hole and said projection with said projection being pulled into said hole; and

wherein said projection is provided at an end of a shaft substantially coaxial with a drum helical gear for transmitting rotational force to said developing roller, and wherein said shaft functions to rotatably support said photosensitive drum in said cartridge frame.

31. A process cartridge according to claim 30, wherein at a side of said photosensitive drum opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, wherein said projection, drum helical gear, engaging portion and shaft are made of integrally molded resin material, and wherein a supporting shaft is projected outwardly in a rotational axis direction from said photosensitive drum, and said supporting shaft functions to rotatably support said photosensitive drum in said cartridge frame.

32. A process cartridge according to claim 30, further comprising a circular or arcuate wall extending around said projection, wherein said wall functions as a guide for engagement between said hole and projection.

33. A process cartridge according to claim 30 or 31, wherein an outer diameter F of said shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of said drum helical gear and an inner diameter D2 of said photosensitive drum, satisfy:

G>

D2, and G>

F≧

C.

34. A process cartridge according to claim 30, wherein corners of said projection are beveled.

35. A process cartridge according to claim 30, further comprising a portion to be urged by a part of the main assembly by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted to the main assembly.

36. A process cartridge according to claim 30, wherein said process cartridge further comprises at least one of a changing roller and a cleaning blade.

37. An electrophotographic image forming apparatus, for forming an image on a recording material, having a main assembly to which a process cartridge is detachably mountable, said apparatus comprising:

a motor;

a driving rotatable member for receiving a driving force from said motor;

a twisted hole formed substantially coaxial with said driving rotatable member, said hole having a substantially triangular cross-section;

means for mounting a process cartridge, the process cartridge including;

a cartridge frame;

an electrophotographic photosensitive drum;

a developing roller for developing a latent image formed on said photosensitive drum; and

a twisted substantially triangular prism projection provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said hole and projection engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said hole and said projection with said projection being pulled into said hole,

wherein said projection is provided at an end of a shaft substantially coaxial with a drum helical gear for transmitting rotational force to said developing roller, and wherein said shaft functions to rotatably support said photosensitive drum in said cartridge frame;

moving means for imparting relative movement between said hole and said projection in a longitudinal direction of said photosensitive drum; and

means for feeding the recording material.

38. An apparatus according to claim 37, wherein at a side opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, and wherein said projection, drum helical gear, engaging portion and shaft are made of integrally molded resin material.

39. An apparatus according to claim 37, wherein said process cartridge further comprises a portion to be urged by a part of the main assembly by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted to the main assembly.

40. An apparatus according to claim 37, wherein said process cartridge further comprises at least one of charging roller and cleaning blade.

41. An apparatus according to claim 37, wherein an outer diameter F of said shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of said drum helical gear and an inner diameter D2 of said photosensitive drum, satisfy:

G>

D2, and G>

F≧

C.

42. An apparatus according to claim 37, wherein an outer diameter D1 of said photosensitive drum and dedendum diameter L of said driving rotatable member satisfy:

1.0×

D1≦

L≦

5.0×

D1, approximately.

43. An apparatus according to claim 37, wherein said driving rotatable member has a module of approximately 0.4-0.7 and has a dedendum diameter L of approximately 30-150 mm, and further has 40-400 teeth.

44. An apparatus according to claim 37, further comprising an openable cover for permitting mounting and demounting of said process cartridge relative to said main assembly, wherein said moving means are for moving said hole away from said projection in interrelation with opening of said cover, and are for moving said hole toward said projection in interrelation with closing of said cover.

45. A process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein said main assembly includes a motor, a main assembly side helical gear for receiving driving force from said motor and a twisted hole substantially coaxial with said main assembly side helical gear, said hole having a substantially triangular cross-section, said process cartridge comprising:

a cartridge frame;

an electrophotographic photosensitive drum;

a charging roller for charging said photosensitive drum;

a developing roller for developing a latent image formed on said photosensitive drum;

a cleaning blade for removing residual toner from said photosensitive drum; and

a twisted substantially triangular prism projection provided at a longitudinal end of said photosensitive drum, wherein when said main assembly side helical gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said main assembly side helical gear to said photosensitive drum through engagement between said hole and said projection with said projection being pulled into said hole; and

wherein said projection is provided at an end of a shaft substantially coaxial with a drum helical gear for transmitting rotational force to said developing roller, and wherein said shaft functions to rotatably support said photosensitive drum in said cartridge frame, and wherein said projection, drum helical gear and shaft are made of integrally molded resin material, and an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said substantially triangular prism projection, satisfy;

D1>

F≧

C.

46. A process cartridge according to claim 45, wherein at a side opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, wherein said projection, drum helical gear, engaging portion and shaft are made of integrally molded resin material.

47. A process cartridge according to claim 45, further comprising a circular or arcuate wall extending around said projection, wherein said wall functions as a guide for engagement between said hole and projection.

48. A process cartridge according to claim 45, wherein corners of said projection are beveled.

49. A process cartridge according to claim 45, further comprising a portion to be urged by a part of the main assembly by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted to the main assembly.

50. An electrophotographic image forming apparatus, for forming an image on a recording material, to which a process cartridge is detachably mountable, said apparatus comprising:

a motor;

a main assembly side helical gear for receiving driving force from said motor;

a twisted hole substantially coaxial with said main assembly side helical gear, said hole having a substantially triangular cross-section, said hole being formed in an end of a circular column projected from a substantially central portion of said main assembly side helical gear;

means for mounting a process cartridge, the process cartridge including;

a cartridge frame;

an electrophotographic photosensitive drum;

a charging roller for charging said photosensitive drum;

a developing roller for developing a latent image formed on said photosensitive drum;

a cleaning blade for removing residual toner from said photosensitive drum; and

a twisted substantially triangular prism projection provided at a longitudinal end of said photosensitive drum, wherein when said main assembly side helical gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said main assembly side helical gear to said photosensitive drum through engagement between said hole and said projection with said projection being pulled into said hole; and

wherein said projection is provided at an end of a shaft substantially coaxial with a drum helical gear for transmitting rotational force to said developing roller, and wherein said shaft functions to rotatably support said photosensitive drum in said cartridge frame, and wherein said projection, drum helical gear and shaft are made of integrally molded resin material, and an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said substantially triangular prism projection, satisfy D1>

F≧

C;

an openable cover for permitting mounting and demounting of said process cartridge relative to said main assembly;

moving means for moving said hole away from said projection in interrelation with opening of said cover, and for moving said hole toward said projection in interrelation with closing of said cover; and

means for feeding the recording material,

wherein a dedendum diameter G of said drum helical gear and an inner diameter D2 of said photosensitive drum, satisfy;

G>

D2, and G>

F≧

C.

51. An apparatus according to claim 50, wherein said main assembly side helical gear has a module of approximately 0.4-0.7 and has a dedendum diameter L of approximately 30-150 mm, and further has 40-400 teeth.

52. A drive transmission part for transmitting a driving force to an electrophotographic photosensitive drum and a developing roller for developing a latent image formed on said photosensitive drum, which are contained in a process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a driving rotatable member for receiving a driving force from said motor, and a twisted hole substantially coaxial with said driving rotatable member, said hole having a polygonal cross-section, said drive transmission part comprising:

a transmission part gear for transmitting a driving force from said main assembly to said developing roller when said process cartridge is mounted to the main assembly;

a shaft substantially coaxial with said transmission part gear; and

a twisted polygonal prism projection provided at an end of said shaft, wherein said projection receives a driving force from the main assembly through engagement between said hole and projection, wherein the driving force is transmitted to said photosensitive drum through said shaft, and is transmitted to said developing roller through said transmission part gear.

53. A part according to claim 52, wherein an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C.

54. A part according to claim 52, wherein said projection, transmission part gear, and shaft are made of integrally molded resin material.

55. A part according to claim 54, wherein said resin material is polyacetal resin, polycarbonate resin, polyamide resin, or polyethyleneterephthalate resin.

56. A drive transmission part for transmitting driving force to an electrophotographic photosensitive drum and a developing roller for developing a latent image formed on said photosensitive drum, which are contained in a process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a main assembly side gear for receiving driving force from said motor, and a twisted hole substantially coaxial with said main assembly side gear, said hole having a substantially triangular cross-section, said drive transmission part comprising:

a helical gear for transmitting driving force from said main assembly to said developing roller when said process cartridge is mounted to the main assembly;

a shaft substantially coaxial with said helical gear; and

a twisted substantially triangular prism projection provided at an end of said shaft, wherein when said main assembly side gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said main assembly side gear to said photosensitive drum through engagement between said hole and said projection with said projection being pulled into said hole, and the driving force is transmitted to said photosensitive drum through said shaft and is transmitted to said developing roller through said helical gear,

wherein said projection, helical gear and shaft are made of integrally molded resin material, and an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy;

D1>

F≧

C.

57. A photosensitive drum, which is contained in a process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a driving rotatable member for receiving a driving force from said motor, and a twisted hole substantially coaxial with said driving rotatable member, said hole having a polygonal cross-section, said photosensitive drum comprising:

a cylinder having a photosensitive layer thereon; and

a drive transmission member mounted to an end of said cylinder, said drive transmission member including;

a drum gear for transmitting a driving force from said main assembly to a developing roller provided in the process cartridge when the process cartridge is mounted to the main assembly;

a shaft substantially coaxial with said drum gear; and

a twisted polygonal prism projection provided at an end of said shaft, wherein said projection receives a driving force from the main assembly through engagement between said hole and projection, wherein the driving force is transmitted to said photosensitive drum through the shaft, and is transmitted to said developing roller through said drum gear.

58. A photosensitive drum according to claim 57, wherein an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C.

59. A photosensitive drum according to claim 57, wherein said projection, drum gear and shaft are made of integrally molded resin material.

60. A photosensitive drum according to claim 59, wherein said resin material is polyacetal resin, polycarbonate resin, polyamide resin, or polyethyleneterephthalate resin.

61. A photosensitive drum according to claim 57, wherein a spur gear is mounted to another end of said cylinder, and wherein said spur gear functions to transmit a driving force for rotating an image transfer roller.

62. A photosensitive drum, which is contained in a process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a main assembly side gear for receiving driving force from said motor, and a twisted hole substantially coaxial with said main assembly side gear, said hole having a substantially triangular cross-section, said photosensitive drum comprising:

a cylinder having a photosensitive layer thereon; and

a drive transmission member mounted to an end of said cylinder, said transmission member including;

a helical gear for transmitting driving force from said main assembly to a developing roller provided in said process cartridge when said process cartridge is mounted to the main assembly;

a shaft substantially coaxial with said helical gear; and

a twisted substantially triangular prism projection provided at an end of said shaft, wherein when said main assembly side gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said main assembly side gear to said photosensitive drum through engagement between said hole and said projection with said projection being pulled into said hole, and the driving force is transmitted to said photosensitive drum through said shaft and is transmitted to said developing roller through said helical gear,

wherein said projection, helical gear and shaft are made of integrally molded resin material, and an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy;

D1>

F≧

C, and

wherein a spur gear is provided, at another end of said cylinder, for transmitting the driving force for rotating an image transfer roller in the main assembly when said process cartridge is mounted to the main assembly.

63. An electrophotographic image forming apparatus for forming an image on a recording material, said apparatus comprising:

an electrophotographic photosensitive drum;

charging means for charging said photosensitive drum;

developing means for developing a latent image formed on said photosensitive drum into a toner image;

transfer means for transferring the toner image onto the recording material;

fixing means for fixing the toner image on the recording material;

a motor;

a driving rotatable member for receiving a driving force from said motor;

a twisted prism projection substantially coaxial with said driving rotatable member, said projection having a polygonal cross-section;

a twisted polygonal hole having a polygonal cross-section and provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said projection and hole engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said projection and said hole with said hole being pulled into said projection; and

moving means for imparting relative movement between said projection and said hole in a longitudinal direction of said photosensitive drum.

64. An apparatus according to claim 63, wherein said projection is formed in an end of a first column projected in a rotational axis direction from said driving rotatable member, and said hole is provided at an end of a shaft projected outwardly in a rotational axis direction from said photosensitive drum.

65. An apparatus according to claim 64, further comprising a drum gear disposed on said photosensitive drum, wherein said hole is provided at a drum gear side of said photosensitive drum, and said drum gear functions to transmit the driving force to a developing roller as said developing means.

66. An apparatus according to claim 65, wherein said driving rotatable member and drum gear are helical gears.

67. An apparatus according to claim 65, wherein an outer diameter F of said shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of the drum gear and an inner diameter D2 of said photosensitive drum, satisfy:

G>

D2, and G>

F≧

C.

68. An apparatus according to claim 64, wherein an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C.

69. An apparatus according to claim 63, further comprising a circular or arcuate wall extending around said hole, said wall functioning as a guide for engagement between said projection and hole.

70. An apparatus according to claim 63 or 69, wherein an outer diameter D1 of said photosensitive drum and dedendum diameter L of said driving rotatable member satisfy:

1.0×

D1≦

L≦

5.0×

D1, approximately.

71. An apparatus according to claim 63 or 69, wherein said driving rotatable member has a module of approximately 0.4-0.7 and has a dedendum diameter L of approximately 30-150 mm, and further has 40-400 teeth.

72. An apparatus according to claim 63 or 68, wherein said projection has a substantially triangular cross-section, and said hole has a substantially triangular cross-section, and wherein corners of triangular shapes are beveled.

73. An apparatus according to claim 63, wherein said photosensitive drum and at least one of said charging means and said developing means are contained in a cartridge which is detachable mountable.

74. An apparatus according to claim 73, further comprising an openable cover for permitting mounting and demounting of said process cartridge relative to a main assembly of said image forming apparatus, wherein said moving means are for moving said projection away from said hole in interrelation with opening of said cover, and are for moving said projection toward said hole in interrelation with closing of said cover.

75. A process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein said main assembly includes a motor, a driving rotatable member for receiving a driving force from said motor and a twisted prism projection substantially coaxial with said driving rotatable member, said projection having a polygonal cross-section, said process cartridge comprising:

an electrophotographic photosensitive drum;

process means actable on said photosensitive drum; and

a twisted polygonal hole having a polygonal cross-section and provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said projection and hole engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said projection and said hole with said hole being pulled into said projection.

76. A process cartridge according to claim 75, wherein said hole is formed as a recess in a shaft projected outwardly in a rotational axis direction from said photosensitive drum, and said shaft functions to rotatably support said photosensitive drum in a cartridge frame.

77. A process cartridge according to claim 76, wherein said shaft is substantially coaxial with a helical gear, and, at a side opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, wherein said hole, helical gear, engaging portion and shaft are made of integrally molded resin material, and the helical gear transmits driving force to a developing roller as said process means.

78. A process cartridge according to claim 75 or 77, further comprising a circular or arcuate wall extending around said hole, said wall functioning as a guide for engagement between said projection and hole.

79. A process cartridge according to claim 76 or 77, wherein an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C.

80. A process cartridge according to claim 75 or 77, wherein said projection has a substantially triangular cross-section, and said hole has a substantially triangular cross-section, and wherein corners of triangular shapes are beveled.

81. A process cartridge according to claim 75, further comprising a portion to be urged by a part of the main assembly by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted the main assembly.

82. A process cartridge according to claim 75, wherein said process cartridge contains said photosensitive drum, and at least one of charging means, developing means and cleaning means, as a unit.

83. An electrophotographic image forming apparatus, for forming an image on a recording material, to which a process cartridge is detachably mountable, said apparatus comprising:

a motor;

a driving rotatable member for receiving a driving force from said motor;

a twisted projection substantially coaxial with said driving rotatable member, said projection having a polygonal cross-section;

means for mounting a process cartridge, the process cartridge including;

an electrophotographic photosensitive drum;

process means actable on said photosensitive drum; and

a twisted polygonal hole provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said projection and hole engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said projection and said hole with said hole being pulled into said projection;

moving means for imparting relative movement between said projection and said hole in a longitudinal direction of said photosensitive drum; and

means for feeding the recording material.

84. An apparatus according to claim 83, wherein a shaft is provided substantially coaxial with a drum gear, and at a side opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, wherein said hole, drum gear, engaging portion and shaft are made of integrally molded resin material, and the drum gear transmits driving force to a developing roller as said process means.

85. An apparatus according to claim 84, wherein said driving rotatable member and drum gear are helical gears. claim 84, wherein said main assembly side gear and drum gear are helical gears.

86. An apparatus according to claim 84, wherein an outer diameter F of said shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of the drum gear and an inner diameter D2 of said photosensitive drum, satisfy:

G>

D2, and G>

F≧

C.

87. An apparatus according to claim 83, further comprising a portion to be urged by a part of the main assembly by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted to the main assembly.

88. An apparatus according to claim 83, wherein said process means includes at least one of charging means, developing means and cleaning means.

89. An apparatus according to claim 83, wherein an outer diameter D1 of said photosensitive drum and dedendum diameter L of said main assembly side gear satisfy:

1.0×

D1≦

L≦

5.0×

D1, approximately.

90. An apparatus according to claim 83, wherein said driving rotatable member has a module of approximately 40.4-0.7 and has a dedendum diameter L of approximately 30-150 mm, and further has 40-400 teeth.

91. An apparatus according to claim 83, further comprising an openable cover for permitting mounting and demounting of said process cartridge relative to a main assembly of said image forming apparatus, wherein said moving means are for moving said projection away from said hole in interrelation with opening of said cover, and are for moving said projection toward said hole in interrelation with closing of said cover.

92. A process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein said main assembly includes a motor, a driving rotatable member for receiving a driving force from said motor and a twisted projection substantially coaxial with said driving rotatable member, said projection having a substantially triangular cross-section, said process cartridge comprising:

a cartridge frame;

an electrophotographic photosensitive drum;

a developing roller for developing a latent image formed on said photosensitive drum; and

a twisted substantially triangular hole provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said projection and hole engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said projection and said hole with said hole being pulled into said projection; and

wherein said hole is provided at an end of a shaft substantially coaxial with a drum helical gear for transmitting rotational force to said developing roller, and wherein said shaft functions to rotatably support said photosensitive drum in said cartridge frame.

93. A process cartridge according to claim 92, wherein at a side opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, and wherein said hole, drum helical gear, engaging portion and shaft are made of integrally molded resin material.

94. A process cartridge according to claim 93, wherein corners of said hole area beveled.

95. A process cartridge according to claim 92, further comprising a circular or arcuate wall extending around said hole, said wall functioning as a guide for engagement between said projection and hole.

96. A process cartridge according to claim 92 or 93, wherein an outer diameter F of said shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of the drum helical gear of said photosensitive drum and an inner diameter D2 of said photosensitive drum, satisfy:

G>

D2, and G>

F≧

C.

97. A process cartridge according to claim 92, further comprising a portion to be urged by a part of the main assembly by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted to the main assembly.

98. A process cartridge according to claim 92, wherein said process cartridge further comprises at least one of a charging roller and a cleaning blade.

99. An electrophotographic image forming apparatus, for forming an image on a recording material, to which a process cartridge is detachably mountable, said apparatus comprising:

a motor;

a driving rotatable member for receiving a driving force from said motor;

a twisted projection substantially coaxial with said driving rotatable member, said projection having a substantially triangular cross-section;

means for mounting a process cartridge, the process cartridge including;

a cartridge frame;

an electrophotographic photosensitive drum;

a developing roller for developing a latent image formed on said photosensitive drum; and

a twisted substantially triangular hole provided at a longitudinal end of said photosensitive drum, wherein when said driving rotatable member rotates with said projection and hole engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said projection and said hole with said hole being pulled into said projection,

wherein said hole is provided at an end of a shaft substantially coaxial with a drum helical gear for transmitting rotational force to said developing roller, and wherein said shaft functions to rotatably support said photosensitive drum in said cartridge frame;

moving means for imparting relative movement between said projection and said hole in a longitudinal direction of said photosensitive drum; and

means for feeding the recording material.

100. An apparatus according to claim 99, wherein at a side opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, and wherein said hole, drum helical gear, engaging portion and shaft are made of integrally molded resin material, and the drum helical gear transmits driving force to said developing roller.

101. An apparatus according to claim 99, wherein said process cartridge further comprises a portion to be urged by a part of a main assembly of said image forming apparatus by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted to the main assembly.

102. An apparatus according to claim 99, wherein said process cartridge contains at least one of charging roller and cleaning blade.

103. An apparatus according to claim 99, wherein an outer diameter F of said shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of the drum helical gear and an inner diameter D2 of said photosensitive drum, satisfy:

G>

D2, and G>

F≧

C.

104. An apparatus according to claim 99, wherein an outer diameter D1 of said photosensitive drum and dedendum diameter L of said driving rotatable member satisfy:

1.0×

D1≦

L≦

5.0×

D1, approximately.

105. An apparatus according to claim 99, wherein said driving rotatable member has a module of approximately 0.4-0.7 and has a dedendum diameter L of approximately 30-150 mm, and further has 40-400 teeth.

106. An apparatus according to claim 99, further comprising an openable cover for permitting mounting and demounting of said process cartridge relative to a main assembly of said image forming apparatus, wherein said moving means are for moving said projection away from said hole in interrelation with opening of said cover, and are for moving said projection toward said hole in interrelation with closing of said cover.

107. A process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein said main assembly includes a motor, a main assembly side helical gear for receiving driving force from said motor and a twisted projection substantially coaxial with said main assembly side helical gear, said projection having a substantially triangular cross-section, said process cartridge comprising:

a cartridge frame;

an electrophotographic photosensitive drum;

a developing roller for developing a latent image formed on said photosensitive drum;

a cleaning blade for removing residual toner from said photosensitive drum; and

a twisted substantially triangular hole provided at a longitudinal end of said photosensitive drum, wherein when said main assembly side helical gear rotates with said projection and hole engaged with each other, rotational driving force is transmitted from said main assembly side helical gear to said photosensitive drum through engagement between said projection and said hole with said hole being pulled into said projection; and

wherein said hole is provided at an end of a shaft substantially coaxial with a drum helical gear for transmitting rotational force to said developing roller, and wherein said shaft functions to rotatably support said photosensitive drum in said cartridge frame, and wherein said hole, drum helical gear and shaft are made of integrally molded resin material, and an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said hole, satisfy;

D1>

F≧

C.

108. A process cartridge according to claim 107, wherein at a side opposite from said shaft, there is provided an engaging portion for engagement with an inner surface of said photosensitive drum, and wherein said hole, drum helical gear, engaging portion and shaft are made of integrally molded resin material.

109. A process cartridge according to claim 107, further comprising a circular or arcuate wall extending around said hole, said wall functioning as a guide for engagement between said projection and hole.

110. A process cartridge according to claim 107, wherein corners of said hole are beveled.

111. A process cartridge according to claim 107, further comprising a portion to be urged by a part of the main assembly by a spring and a portion to be contacted to a fixed portion of the main assembly, when said process cartridge is mounted to the main assembly.

112. An electrophotographic image forming apparatus, for forming an image on a recording material, to which a process cartridge is detachably mountable, said apparatus comprising:

a motor;

a main assembly side helical gear for receiving driving force from said motor;

a twisted projection substantially coaxial with said main assembly side helical gear, said projection having a substantially triangular cross-section, and said projection being formed in an end of a circular column projected from a substantially central portion of said main assembly side helical gear;

means for mounting a process cartridge, the process cartridge including;

a cartridge frame;

an electrophotographic photosensitive drum;

a developing roller for developing a latent image formed on said photosensitive drum;

a cleaning blade for removing residual toner from said photosensitive drum; and

a twisted substantially triangular hole provided at a longitudinal end of said photosensitive drum, wherein when said main assembly side helical gear rotates with said projection and hole engaged with each other, rotational driving force is transmitted from said main assembly side helical gear to said photosensitive drum through engagement between said projection and said hole with said hole being pulled into said projection; and

wherein said hole is provided at an end of a shaft substantially coaxial with a drum helical gear for transmitting rotational force to said developing roller, and wherein said shaft functions to rotatably support said photosensitive drum in said cartridge frame, and wherein said hole, drum helical gear and shaft are made of integrally molded resin material, and an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy D1>

F≧

C;

an openable cover for permitting mounting and demounting of said process cartridge relative to a main assembly of said image forming apparatus;

moving means for moving said projection away from said hole in interrelation with opening of said cover, and for moving said projection toward said hole in interrelation with closing of said cover; and

means for feeding the recording material,

wherein a dedendum diameter G of the drum helical gear and an inner diameter D2 of said photosensitive drum, satisfy;

G>

D2, and G>

F≧

C.

113. An apparatus according to claim 112, wherein said main assembly side helical gear has a module of approximately 0.4-0.7 and has a dedendum diameter L of approximately 30-150 mm, and further has 40-400 teeth.

114. A drive transmission part for transmitting a driving force to an electrophotographic photosensitive drum and a developing roller for developing a latent image formed on said photosensitive drum, which are contained in a process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a driving rotatable member for receiving a driving force from said motor, and a twisted projection substantially coaxial with said driving rotatable member, said projection having a polygonal cross-section, said drive transmission part comprising:

a gear for transmitting a driving force from said main assembly to said developing roller when said process cartridge is mounted to the main assembly;

a shaft substantially coaxial with said gear; and

a twisted polygonal hole provided at an end of said shaft, wherein said hole receives a driving force from the main assembly through engagement between said projection and hole, wherein the driving force is transmitted to said photosensitive drum through the shaft, and is transmitted to said developing roller through said gear.

115. A part according to claim 114, wherein an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C.

116. A part according to claim 114, wherein said hole, gear and shaft are made of integrally molded resin material.

117. A part according to claim 116, wherein said resin material is polyacetal resin, polycarbonate resin, polyamide resin, or polyethyleneterephthalate resin.

118. A drive transmission part for transmitting driving force to an electrophotographic photosensitive drum and a developing roller for developing a latent image formed on said photosensitive drum, which are contained in a process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a main assembly side gear for receiving driving force from said motor, and a twisted projection substantially coaxial with said main assembly side gear, said projection having a substantially triangular cross-section, said drive transmission part comprising:

a helical gear for transmitting driving force from said main assembly to said developing roller when said process cartridge is mounted to the main assembly;

a shaft substantially coaxial with said helical gear; and

a twisted substantially triangular hole provided at an end of said shaft, wherein when said main assembly side gear rotates with said projection and hole engaged with each other, rotational driving force is transmitted from said main assembly side gear to said photosensitive drum through engagement between said projection and said hole with said hole being pulled into said projection, and the driving force is transmitted to said photosensitive drum through said shaft and is transmitted to said developing roller through said helical gear,

wherein said hole, helical gear and shaft are made of integrally molded resin material, and an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy;

D1>

F≧

C.

119. A photosensitive drum, which is contained in a process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a driving rotatable member for receiving a driving force from said motor, and a twisted projection substantially coaxial with said driving rotatable member, said projection having a polygonal cross-section, said photosensitive drum comprising:

a cylinder having a photosensitive layer thereon; and

a drive transmission member mounted to an end of said cylinder, said transmission member including;

a gear for transmitting a driving force from said main assembly to a developing roller when said process cartridge is mounted to the main assembly;

a shaft substantially coaxial with said gear; and

a twisted polygonal hole provided at an end of said shaft, wherein said hole receives driving force from the main assembly through engagement between said projection and hole, wherein the driving force is transmitted to said photosensitive drum through the shaft, and is transmitted to said developing roller through said gear.

120. A photosensitive drum according to claim 119, wherein an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C.

121. A photosensitive drum according to claim 119, wherein said hole, gear and shaft are made of integrally molded resin material.

122. A photosensitive drum according to claim 121, wherein said resin material is polyacetal resin, polycarbonate resin, polyamide resin, or polyethyleneterephthalate resin.

123. A photosensitive drum according to claim 119, wherein a spur gear is mounted to an end of said cylinder, and wherein said spur gear functions to transmit a driving force for rotating an image transfer roller.

124. A photosensitive drum, which is contained in a process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a main assembly side gear for receiving driving force from said motor, and a twisted projection substantially coaxial with said main assembly side gear, said projection having a polygonal cross-section, said photosensitive drum comprising:

a cylinder having a photosensitive layer thereon; and

a drive transmission member mounted to an end of said cylinder, said transmission member including;

a helical gear for transmitting driving force from said main assembly to a developing roller of said process cartridge when said process cartridge is mounted to the main assembly;

a shaft substantially coaxial with said helical gear; and

a twisted substantially triangular hole provided at an end of said shaft, wherein when said main assembly side gear rotates with said projection and hole engaged with each other, rotational driving force is transmitted from said main assembly side gear to said photosensitive drum through engagement between said projection and said hole with said hole being pulled into said projection, and the driving force is transmitted to said photosensitive drum through said shaft and is transmitted to said developing roller through said helical gear,

wherein said hole, helical gear and shaft are made of integrally molded resin material, and an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft and a diameter C of a circumscribed circle of said projection, satisfy;

D1>

F≧

C, and

wherein a spur gear is provided, at an end of said cylinder, for transmitting the driving force for rotating an image transfer roller in the main assembly when said process cartridge is mounted to the main assembly.

125. A process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a driven rotatable member for receiving driving force from said motor and a twisted recess or projection having a non-circular cross-section and substantially coaxial with a rotation axis of said driven rotatable member, said process cartridge comprising:

a rotatable electrophotographic photosensitive drum;

process means actable on said photosensitive drum; and

a twisted projection or recess provided at a longitudinal end of said photosensitive drum, having a non-circular cross-section and substantially coaxial with a rotation axis of said photosensitive drum, wherein said projection or recess of said photosensitive drum has such a dimension and configuration that said projection or recess can take a first relative rotational position with respect to said recess or projection of said driven rotatable member in which relative rotational movement therebetween is permitted, and a second relative rotational position with respect to said recess or projection of said driven rotatable member in which relative rotational movement is prevented in one rotational direction, while the rotation axis of said driven rotatable member and the rotation axis of said photosensitive drum are substantially aligned.

126. A process cartridge according to claim 125, wherein said recess or projection of said driven rotatable member and said projection or recess of said photosensitive drum are contacted substantially at three twisted lines.

127. A process cartridge according to claim 126, wherein said three twisted lines constitute a substantially equilateral triangle.

128. A process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein said main assembly includes a motor, a driving rotatable member for receiving a driving force from said motor and a hole defined by twisted surfaces, said hole being substantially coaxial with said driving rotatable member, said process cartridge comprising:

an electrophotographic photosensitive drum;

process means actable on said photosensitive drum; and

a twisted projection engageable with said twisted surfaces, said projection being provided at a longitudinal end of said photosensitive drum,

wherein, when said driving rotatable member rotates with said hole and projection engaged with each other, a rotational driving force is transmitted from said driving rotatable member to said photosensitive drum through engagement between said hole and said projection.

129. A process cartridge according to claim 128, wherein said projection is projected from an end of a shaft projected outwardly in a rotational axis direction from a said photosensitive drum, and said shaft functions to rotatably support said photosensitive drum in a cartridge frame.

130. A process according to claim 129, wherein an outer diameter D1 of said photosensitive drum, an outer diameter F of said shaft, and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C, and

wherein said projection and shaft are of integrally molded resin material.

131. A process cartridge according to claim 129, wherein an outer diameter F of said shaft, a diameter of C of a circumscribed circle of said projection, a dedendum diameter G of the gear of said photosensitive drum and an inner diameter of said photosensitive drum D2, satisfy:

G>

D2, and F>

G≧

C, and

wherein said projection, said shaft and said drum gear are composed of integrally molded resin material.

132. A process cartridge according to claim 128, 130 or 131, wherein said hole has a substantially triangular cross-section with beveled, triangular-shaped corners, and said projection has a substantially triangular cross-section with beveled, triangular-shaped corners.

133. A process cartridge according to claim 128, wherein said process means includes at least one of charging means, developing means, and cleaning means as a unit.

134. A drive transmission part, for transmitting a driving force to an electrophotographic photosensitive drum and a developing roller for developing a latent image formed on said photosensitive drum, usable with an electrophotographic image forming apparatus for forming an image on a recording material, said apparatus including a motor, a driving rotatable member for receiving a driving force from said motor, and a hole defined by twisted surfaces, said hole being substantially coaxial with said driving rotatable member, said drive transmission part comprising:

a transmission part gear for transmitting a driving force to said developing roller;

a shaft substantially coaxial with said transmission part gear; and

a twisted projection engageable with said twisted surfaces, said projection being provided at an end of said shaft,

wherein said projection receives a driving force from said driving rotatable member through engagement between said hole and said projection, and wherein the driving force is transmitted to said photosensitive drum through the shaft, and is transmitted to said developing roller through said transmission part gear.

135. A drive transmission part according to claim 134, wherein said projection, said transmission part gear, and said shaft are composed of integrally molded resin material.

136. A drive transmission part according to claim 134 or 135, wherein said hole has a substantially triangular cross-section with beveled, triangular-shaped corners, and said projection has a substantially triangular cross-section with beveled, triangular-shaped corners.

137. A drive transmission part according to claim 136, wherein an outer diameter F of said shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of said transmission part, and an inner diameter of said photosensitive drum D2, satisfy:

G>

D2, and G>

F≧

C.

138. A drive transmission part according to claim 137, wherein said projection receives an attraction force attracting it into the hole when said projection transmits a rotational force to the photosensitive drum while being in engagement with the hole.

139. A photosensitive drum, usable with an electrophotographic image forming apparatus for forming an image on a recording material, said apparatus including a motor, a driving rotatable member for receiving a driving force from said motor, and a hole defined by twisted surfaces, said hole being substantially coaxial with said driving, said photosensitive drum comprising:

a cylinder having a photosensitive layer thereon; and

a drive transmission member mounted to an end of said cylinder, said transmission member including;

a transmission member gear for transmitting a driving force from said driving rotatable member to a developing roller;

a shaft substantially coaxial with said transmission member gear; and

a twisted projection engageable with said twisted surfaces, said projection being provided at an end of said shaft,

wherein said projection receives a driving force from said driving rotatable member through engagement between said hole and said projection, and wherein the driving force is transmitted to said photosensitive drum through the shaft, and is transmitted to said developing roller through said transmission member gear.

140. A drum according to claim 139, wherein an outer diameter D1 of said photosensitive drum, and an outer diameter F of said shaft, and a diameter C of a circumscribed circle of said projection, satisfy:

D1>

F≧

C, and

wherein said projection and shaft are composed of integrally molded resin material.

141. A drum according to claim 139, wherein an outer diameter F of said shaft, a diameter C of a circumscribed circle of said projection, a dedendum diameter G of a gear of the transmission member gear, and an inner diameter of said photosensitive drum D2, satisfy:

G>

D2, and G>

F≧

C, and

wherein said projection, said shaft and said transmission member gear are composed of integrally molded resin material.

142. A drum according to claim 139, wherein said transmission member gear, said shaft and said projection are composed of integrally molded resin material.

143. A drum according to claim 139, 140, 141, or 142, wherein said hole has a substantially triangular cross-section with beveled, triangular-shaped corners, and said projection has a substantially triangular cross-section, with beveled, triangular-shaped corners.

144. A drum according to claim 143, wherein said projection receives an attraction force attracting it into the hole when said projection transmits a rotational force to the photosensitive drum while being in engagement with the hole.

145. A process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a driving rotatable member for receiving driving force from said motor and having a twisted recess or projection having a non-circular cross-section and being substantially coaxial with a rotation axis of said driving rotatable member, said process cartridge comprising:

a rotatable electrophotographic photosensitive drum;

process means actable on said photosensitive drum; and

a twisted projection or recess provided at a longitudinal end of said photosensitive drum, having a non-circular cross-section and being substantially coaxial with a rotation axis of said photosensitive drum, wherein said projection or recess of said photosensitive drum has such a dimension and configuration that said projection or recess of said photosensitive drum can take a first relative rotational position with respect to said recess or projection of said driving rotatable member in which relative rotational movement therebetween is permitted, and a second relative rotational position with respect to said recess or projection of said driving rotatable member in which relative rotational movement is prevented in one rotational direction, while the rotation axis of said driving rotatable member and the rotation axis of said photosensitive drum are substantially aligned, and the photosensitive drum is urged in a longitudinal direction of said photosensitive drum by engagement between the recess or projection of the driving rotatable member and said projection or recess of said photosensitive drum.

146. A process cartridge detachably mountable to a main assembly of an image forming apparatus for forming an image on a recording material, said main assembly including a motor, a driving rotatable member for receiving driving force from said motor and having a twisted recess or projection having a non-circular cross-section and being substantially coaxial with a rotation axis of said driving rotatable member, said process cartridge comprising:

a rotatable electrophotographic photosensitive drum;

process means actable on said photosensitive drum; and

a twisted projection or recess provided at a longitudinal end of said photosensitive drum, having a non-circular cross-section and being substantially coaxial with a rotation axis of said photosensitive drum, wherein said projection or recess of said photosensitive drum has such a dimension and configuration that said projection or recess of said photosensitive drum can take a first relative rotational position with respect to said recess or projection of said driving rotatable member in which relative rotational movement therebetween is permitted, and a second relative rotational position with respect to said recess or projection of said driving rotatable member in which relative rotational movement is prevented in one rotational direction by engagement between the twisted recess or projection of the driving rotatable member and said twisted projection or recess of said photosensitive drum, while substantially aligning the rotation axis of said photosensitive drum with the rotation axis of said driving rotatable member and urging the photosensitive drum in a longitudinal direction of said photosensitive drum by engagement therebetween.