Coupling part, photosensitive drum, process cartridge and electrophotographic image forming apparatus

Abstract

A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein the main assembly includes a motor, a main assembly side gear for receiving driving force from the motor, a hole defined by twisted surfaces, the hole being substantially coaxial with the gear, and a main assembly side grounding contact provided in the hole, the process cartridge includes an electrophotographic photosensitive drum; process means actable on the photosensitive drum; and a projection engageable with the twisted surfaces, the projection being 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 engagement between the hole and the projection; and a cartridge side grounding contact electrically connected with the electrophotographic photosensitive drum for electrically grounding the electrophotographic photosensitive drum when the process cartridge is mounted to the main assembly of the apparatus, the cartridge side grounding contact being provided on the projection so as to be electrically connectable with the main assembly side grounding contact.

What is claimed is:  
     
         1 . A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein said main assembly includes a motor, a main assembly side gear for receiving driving force from said motor, a hole defined by twisted surfaces, said hole being substantially coaxial with said gear, and a main assembly side grounding contact provided in said hole, said process cartridge comprising: 
 an electrophotographic photosensitive drum;    process means actable on said photosensitive drum; and    a projection engageable with said twisted surfaces, said projection being provided at a longitudinal end of said photosensitive drum, wherein when said main assembly side gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said gear to said photosensitive drum through engagement between said hole and said projection; and    a cartridge side grounding contact electrically connected with said electrophotographic photosensitive drum for electrically grounding said electrophotographic photosensitive drum when said process cartridge is mounted to the main assembly of said apparatus, said cartridge side grounding contact being provided on said projection so as to be electrically connectable with said main assembly side grounding contact.    
     
     
         2 . A process cartridge according to  claim 1 , wherein said cartridge side grounding contact is disposed inside a free end surface of said projection.  
     
     
         3 . A process cartridge according to  claim 1 , wherein said cartridge side grounding contact is positioned coaxially with said projection.  
     
     
         4 . A process cartridge according to  claim 3 , wherein said projection is provided on one side of a coupling member mounted to one end of said electrophotographic photosensitive drum.  
     
     
         5 . A process cartridge according to  claim 4 , wherein said coupling member includes a shaft portion rotatably supported on a cartridge frame, a gear portion for transmitting rotational driving force to a developing roller, and an engaging portion for engagement with said electrophotographic photosensitive drum, wherein said projection is provided at an end of said shaft portion, wherein said cartridge side grounding contact is coaxial with said coupling member, and constitutes a free end surface of an electroconductive member which penetrates inside of said coupling member in its axial direction.  
     
     
         6 . A process cartridge according to  claim 5 , wherein a grounding plate is mounted to such a portion of said coupling member as is inside said electrophotographic photosensitive drum, and said grounding plate includes a hole for permitting penetration of said electroconductive member therethrough, a first contact portion contacted to said electroconductive member, and a second contact portion contacted to an inner surface of said electrophotographic photosensitive drum.  
     
     
         7 . A process cartridge according to  claim 6 , wherein said electroconductive member is of metal, and is fixed to said coupling member.  
     
     
         8 . A process cartridge according to  claim 6 , wherein said electroconductive member is of metal and is slidable relative to said coupling member.  
     
     
         9 . A process cartridge according to  claim 7  or  8 , wherein said electroconductive member is of phosphor bronze, stainless steel or steel material plated with nickel.  
     
     
         10 . A process cartridge according to  claim 1  or  6 , wherein said projection is in the form of a twisted prism.  
     
     
         11 . A process cartridge according to  claim 10 , wherein said prism is a substantially triangular prism.  
     
     
         12 . A process cartridge according to  claim 1  or  6 , wherein said projection includes a plurality of radially projected portions.  
     
     
         13 . A process cartridge according to  claim 1  or  6 , wherein said projection is in the form of a flat plate.  
     
     
         14 . A process cartridge according to  claim 13 , wherein said flat plate is substantially triangular.  
     
     
         15 . A process cartridge according to  claim 10 , wherein said coupling member is of polyacetal, polycarbonate or polybutylene terephthalate material.  
     
     
         16 . A process cartridge according to  claim 1 , wherein said process means includes at least one of a charging member for effecting charging, a developing member for developing a latent image formed on said photosensitive drum and a cleaning member for removing residual toner from said photosensitive drum.  
     
     
         17 . A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein said main assembly includes a motor, a main assembly side gear for receiving driving force from said motor and a hole defined by twisted surface, said hole being substantially coaxial with said gear and a main assembly side grounding contact provided in said hole, said process cartridge comprising: 
 (a) an electrophotographic photosensitive drum;    (b) process means actable on said photosensitive drum; and    (c) a twisted projection engageable with said twisted surfaces, said projection being provided at a longitudinal end of said photosensitive drum, wherein when said main assembly side gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said gear to said photosensitive drum through engagement between said hole and said projection;    (d) a coupling member mounted to one end of said electrophotographic photosensitive drum, said coupling member including a shaft portion rotatably supported on a cartridge frame, a gear portion for transmitting rotational driving force to a developing roller, and an engaging portion for engagement with said electrophotographic photosensitive drum, and wherein said projection is provided on an end of said shaft portion;    (e) an electroconductive member located coaxially with said coupling member and extending through said coupling member in its axial direction;    (f) a grounding member mounted to such a portion of said coupling member as is inside said electrophotographic photosensitive drum, said grounding member including a hole for permitting penetration of said electroconductive member therethrough, a first contact portion contacted to said electroconductive member, and a second contact portion contacted an inner surface of said electrophotographic photosensitive drum;    (g) a cartridge side grounding contact electrically connected to said electrophotographic photosensitive drum to electrically grounding said electrophotographic photosensitive drum when said process cartridge is mounted to the main assembly of said apparatus, said cartridge side grounding contact being provided on said projection so as to be electrically connectable with said main assembly side grounding contact, wherein said cartridge side grounding contact is a free end surface of said electroconductive member and is disposed inside a free end surface of said projection.    
     
     
         18 . A process cartridge according to  claim 17 , wherein said electroconductive member is of metal, and is fixed to said coupling member.  
     
     
         19 . A process cartridge according to  claim 17 , wherein said electroconductive member is of phosphor bronze, stainless steel or steel material plated with nickel.  
     
     
         20 . A process cartridge according to  claim 17 ,  18  or  19 , wherein said projection is in the form of a twisted prism.  
     
     
         21 . A process cartridge according to  claim 20 , wherein said prism is a substantially triangular prism.  
     
     
         22 . A process cartridge according to  claim 17 , wherein said coupling member is of polyacetal, polycarbonate or polybutylene terephthalate material.  
     
     
         23 . A process cartridge according to  claim 17 , wherein said process means includes at least one of a charging member for effecting charging, a developing member for developing a latent image formed on said photosensitive drum and a cleaning member for removing residual toner from said photosensitive drum.  
     
     
         24 . A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus for forming an image on a recording material, said main assembly including a motor, a driving rotatable 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 drive rotatable member, and a main assembly side grounding contact provided in said recess or on said projection, comprising: 
 a rotatable electrophotographic photosensitive member;    process means actable on said photosensitive member; and    a twisted projection or recess provided at a longitudinal end of said image bearing member, having a non-circular cross-section and substantially coaxial with a rotation axis of said electrophotographic photosensitive member, wherein said projection or recess of said electrophotographic photosensitive member has such a dimension and configuration that it 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 electrophotographic photosensitive member are substantially aligned;    a cartridge side grounding contact electrically connected to said electrophotographic photosensitive member to electrically grounding said electrophotographic photosensitive member when said process cartridge is mounted to the main assembly of said apparatus, said cartridge side grounding contact being provided on said projection or in said recess so as to be electrically connectable with said main assembly side grounding contact.    
     
     
         25 . A process cartridge according to  claim 24 , wherein said recess or projection of said driving rotatable member and said projection or recess of said electrophotographic photosensitive member are contacted substantially at three twisted lines.  
     
     
         26 . A process cartridge according to  claim 25 , wherein said three points constitute a substantially equilateral triangle.  
     
     
         27 . A process cartridge according to  claim 24 , wherein said projection or recess is provided at one end of said coupling member mounted to an end of said electrophotographic photosensitive member.  
     
     
         28 . A process cartridge according to  claim 27 , wherein said coupling member includes a shaft portion rotatably supported on a cartridge frame, a gear portion for transmitting rotational driving force to a developing roller, and an engaging portion for engagement with said electrophotographic photosensitive drum wherein said projection or recess is provided at an end of said shaft portion, and wherein said cartridge side grounding contact is coaxial with said coupling member and is a free end surface of an electroconductive member extending through said coupling member in its axial direction.  
     
     
         29 . A process cartridge according to  claim 28 , wherein a grounding plate is mounted to such a portion of said coupling member as is inside said electrophotographic photosensitive member, said grounding plate including a hole for permitting penetration of said electroconductive member therethrough, a first contact portion contacted to said electroconductive member and a second contact portion contacted to an inside of said electrophotographic photosensitive member.  
     
     
         30 . A process cartridge according to  claim 29 , wherein said electroconductive member is of metal, and is fixed to said coupling member.  
     
     
         31 . A process cartridge according to  claim 29 , wherein said electroconductive member is of metal and is slidable relative to said coupling member.  
     
     
         32 . A process cartridge according to  claim 30  or  31 , wherein said electroconductive member is of phosphor bronze, stainless steel or steel material plated with nickel.  
     
     
         33 . A process cartridge according to  claim 24  or  29 , wherein said projection is in the form of a twisted prism.  
     
     
         34 . A process cartridge according to  claim 33 , wherein said prism is a substantially triangular prism.  
     
     
         35 . An electrophotographic image formation mounting for forming an image on a recording material, to which a process cartridge is detachably mountable, said apparatus comprising: 
 (a) a motor;    (b) a main assembly side gear for receiving driving force from said motor;    (c) a hole defined by twisted surfaces, said hole being substantially coaxial with said gear;    (d) a main assembly side grounding contact provided in said hole;    (e) a mounting portion for detachably mounting a process cartridge, said process cartridge including: an electrophotographic photosensitive drum; process means actable on said photosensitive drum; and a projection engageable with said twisted surfaces, said projection being provided at a longitudinal end of said photosensitive drum, wherein when said main assembly side gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said gear to said photosensitive drum through engagement between said hole and said projection; and a cartridge side grounding contact electrically connected with said electrophotographic photosensitive drum for electrically grounding said electrophotographic photosensitive drum when said process cartridge is mounted to the main assembly of said apparatus, said cartridge side grounding contact being provided on said projection so as to be electrically connectable with said main assembly side grounding contact.    
     
     
         36 . An electrophotographic image formation mounting for forming an image on a recording material, to which a process cartridge is detachably mountable, said apparatus comprising: 
 (a) a motor;    (b) a main assembly side gear for receiving driving force from said motor;    (c) a hole defined by twisted surfaces, said hole being substantially coaxial with said gear;    (d) a main assembly side grounding contact provided in said hole;    (e) a mounting portion for detachably mounting a process cartridge, said process cartridge including: 
 (a) an electrophotographic photosensitive drum; (b) process means actable on said photosensitive drum; and  
 (d) a twisted projection engageable with said twisted surfaces, said projection being provided at a longitudinal end of said photosensitive drum, wherein when said main assembly side gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said gear to said photosensitive drum through engagement between said hole and said projection; (d) a coupling member mounted to one end of said electrophotographic photosensitive drum, said coupling member including a shaft portion rotatably supported on a cartridge frame, a gear portion for transmitting rotational driving force to a developing roller, and an engaging portion for engagement with said electrophotographic photosensitive drum, and wherein said projection is provided on an end of said shaft portion; (e) an electroconductive member located coaxially with said coupling member and extending through said coupling member in its axial direction; (f) a grounding member mounted to such a portion of said coupling member as is inside said electrophotographic photosensitive drum, said grounding member including a hole for permitting penetration of said electroconductive member therethrough, a first contact portion contacted to said electroconductive member, and a second contact portion contacted an inner surface of said electrophotographic photosensitive drum; (g) a cartridge side grounding contact electrically connected to said electrophotographic photosensitive drum to electrically grounding said electrophotographic photosensitive drum when said process cartridge is mounted to the main assembly of said apparatus, said cartridge side grounding contact being provided on said projection so as to be electrically connectable with said main assembly side grounding contact, wherein said cartridge side grounding contact is a free end surface of said electroconductive member and is disposed inside a free end surface of said projection.  
   
     
     
         37 . An apparatus according to  claim 35  or  36 , wherein said main assembly side grounding contact is a free end surface of an electroconductive member extended through said gear in a direction of its width.  
     
     
         38 . A process cartridge according to  claim 37 , wherein said electroconductive member is movable in the longitudinal direction, and is urged by an elastic member.  
     
     
         39 . A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein said main assembly includes a motor, a main assembly side gear for receiving driving force from said motor and a hole defined by twisted surfaces, said hole being substantially coaxial with said gear and a main assembly side grounding contact provided in said hole, said process cartridge comprising: 
 an electrophotographic photosensitive drum;    process means actable on said photosensitive drum; and    a projection engageable with said twisted surfaces, said projection being provided at a longitudinal end of said photosensitive drum, wherein when said main assembly side gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said gear to said photosensitive drum through engagement between said hole and said projection;    wherein said projection is of an electroconductive material for electrical connection with said electrophotographic photosensitive drum and with said main assembly side grounding contact to electrically grounding said electrophotographic photosensitive drum when said process cartridge is mounted to the main assembly of said apparatus.    
     
     
         40 . A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, wherein said main assembly includes a motor, a main assembly side gear for receiving driving force from said motor, a hole defined by twisted surfaces, said hole being substantially coaxial with said gear, and a main assembly side grounding contact provided in said hole, 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 main assembly side gear rotates with said hole and projection engaged with each other, rotational driving force is transmitted from said gear to said photosensitive drum through engagement between said hole and said projection; and    wherein said projection is of an electroconductive material for electrical connection with said electrophotographic photosensitive drum and with said main assembly side grounding contact to electrically grounding said electrophotographic photosensitive drum when said process cartridge is mounted to the main assembly of said apparatus.    
     
     
         41 . An apparatus according to  claim 39  or  40 , wherein said projection is provided at an end of a coupling member mounted to one end of said electrophotographic photosensitive drum, said coupling member including a circular portion rotatably supported on a cartridge frame, gear portion for transmitting rotational driving force to a developing roller, and an engaging portion for engagement with said electrophotographic photosensitive drum, wherein said projection is provided to and end of said circular portion.  
     
     
         42 . A process cartridge according to  claim 41 , wherein said coupling member is made of an electroconductive material with said projection.  
     
     
         43 . An apparatus according to  claim 41 , wherein said coupling member has an electroconductive member portion which constitutes a path for electric connection between said projection and said electrophotographic photosensitive drum, and an anti-wearing material which constitutes said gear portion.  
     
     
         44 . A process cartridge according to  claim 41 ,  42  or  43 , wherein said electroconductive member is of polyacetal containing electroconductive filler, polyphenylenesulfone containing electroconductive filler or polyamide containing electroconductive filler.  
     
     
         45 . An electrophotographic photosensitive drum, which is contained in a process cartridge detachably mountable to a main assembly of an electrophotographic 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 formed substantially at a center of said gear, said hole having a polygonal cross-section; 
 a cylinder having a photosensitive layer thereon;    a drive transmission member mounted to an end of said cylinder, said transmission member including: 
 a gear for transmitting driving force to said developing roller from said main assembly to said developing roller when said process cartridge is mounted to the main assembly;  
 a shaft provided substantially at a center of said gear;  
 a twisted projection provided at an end of said shaft, wherein said projection receives 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 gear;  
 a cartridge side grounding contact electrically connected with said electrophotographic photosensitive drum, said cartridge side grounding contact being provided on said projection so as to be electrically connectable to the main assembly side grounding contact.  
   
     
     
         46 . A drum according to  claim 45 , wherein an outer diameter D 1  of said photosensitive drum, an outer diameter F and a diameter C of a circumscribed circle of said substantially triangular prism, satisfy: 
 D 1 >F≧C.  
 
     
     
         47 . A drum according to  claim 45 , wherein projection, helical gear and shaft are of integrally molded resin material.  
     
     
         48 . A drum according to  claim 45 ,  46  or  47 , wherein said resin material is polyacetal resin, polycarbonate resin, or polyethyleneterephthalate resin.  
     
     
         49 . A drum according to  claim 45 , wherein a spur gear is mounted to an end of said cylinder, wherein said spur gear functions to transmit a driving force for rotating an image transfer roller.  
     
     
         50 . A drum according to  claim 45 , wherein said cartridge side grounding contact is disposed inside a free end surface of said projection.  
     
     
         51 . A drum according to  claim 45 , wherein said cartridge side grounding contact is positioned coaxially with said projection.  
     
     
         52 . A drum according to  claim 51 , wherein said projection is provided on one side of a coupling member mounted to one end of said electrophotographic photosensitive drum.  
     
     
         53 . A drum according to  claim 52 , wherein said coupling member includes a shaft portion rotatably supported on a cartridge frame, a gear portion for transmitting rotational driving force to a developing roller, and an engaging portion for engagement with said electrophotographic photosensitive drum, wherein said projection is provided at an end of said shaft portion, wherein said cartridge side grounding contact is coaxial with said coupling member, and constitutes a free end surface of an electroconductive member which penetrates inside of said coupling member in its axial direction.  
     
     
         54 . A drum according to  claim 53 , wherein a grounding plate is mounted to such a portion of said coupling member as is inside said electrophotographic photosensitive drum, and said grounding plate includes a hole for permitting penetration of said electroconductive member therethrough, a first contact portion contacted to said electroconductive member, and a second contact portion contacted to an inner surface of said electrophotographic photosensitive drum.  
     
     
         55 . A drum according to  claim 54 , wherein said electroconductive member is of metal, and is fixed to said coupling member.  
     
     
         56 . A drum according to  claim 54  or  55 , wherein said electroconductive member is of phosphor bronze, stainless steel or steel material plated with nickel.  
     
     
         57 . A drum according to  claim 45  or  54 , wherein said projection is in the form of a twisted prism.  
     
     
         58 . A drum according to  claim 57 , wherein said prism is a substantially triangular prism.  
     
     
         59 . A coupling 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 electrophotographic 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 formed substantially at a center of said gear, said hole having a polygonal cross-section; 
 a gear for transmitting driving force to said developing roller from said main assembly to said developing roller when said process cartridge is mounted to the main assembly;    a shaft provided substantially at a center of said gear;    a twisted projection provided at an end of said shaft, wherein said projection receives 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 gear;    a cartridge side grounding contact electrically connected to said electrophotographic photosensitive drum, said cartridge side grounding contact being provided on said projection so as to be electrically connected to said main assembly side grounding contact to electrically grounding said electrophotographic photosensitive drum.    
     
     
         60 . A coupling part according to  claim 59 , wherein an outer diameter D 1  of said photosensitive drum, an outer diameter F and a diameter C of a circumscribed circle of said substantially triangular prism, satisfy: 
 D 1 >F≧C.  
 
     
     
         61 . A coupling part according to  claim 59 , wherein projection, helical gear and shaft are of integrally molded resin material.  
     
     
         62 . A coupling part according to  claim 59 ,  60  or  61 , wherein said resin material is polyacetal resin, polycarbonate resin, or polyethyleneterephthalate resin.  
     
     
         63 . A coupling part according to  claim 59 , wherein said cartridge side grounding contact is disposed inside a free end surface of said projection.  
     
     
         64 . A coupling part according to  claim 59 , wherein said cartridge side grounding contact is positioned coaxially with said projection.  
     
     
         65 . A coupling part according to  claim 64 , wherein said projection is provided on one side of a coupling member mounted to one end of said electrophotographic photosensitive drum.  
     
     
         66 . A coupling part according to  claim 65 , wherein said coupling member includes a shaft portion rotatably supported on a cartridge frame, a gear portion for transmitting rotational driving force to a developing roller, and an engaging portion for engagement with said electrophotographic photosensitive drum, wherein said projection is provided at an end of said shaft portion, wherein said cartridge side grounding contact is coaxial with said coupling member, and constitutes a free end surface of an electroconductive member which penetrates inside of said coupling member in its axial direction.  
     
     
         67 . A coupling part according to  claim 66 , wherein a grounding plate is mounted to such a portion of said coupling member as is inside said electrophotographic photosensitive drum, and said grounding plate includes a hole for permitting penetration of said electroconductive member therethrough, a first contact portion contacted to said electroconductive member, and a second contact portion contacted to an inner surface of said electrophotographic photosensitive drum.  
     
     
         68 . A coupling part according to  claim 67 , wherein said electroconductive member is of metal, and is fixed to said coupling member.  
     
     
         69 . A coupling part according to  claim 67  or  68 , wherein said electroconductive member is of phosphor bronze, stainless steel or steel material plated with nickel.  
     
     
         70 . A coupling part according to  claim 59  or  67 , wherein said projection is in the form of a twisted prism.  
     
     
         71 . A coupling part according to claim  70 , wherein said prism is a substantially triangular prism.  
     
     
         72 . 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 formed substantially at a center of said gear, said hole having a polygonal cross-section; 
 a gear for transmitting driving force to said developing roller from said main assembly to said developing roller when said process cartridge is mounted to the main assembly;    a shaft provided substantially at a center of said gear;    a twisted projection provided at an end of said shaft, wherein said projection receives 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 gear;    a grounding contact for electrically grounding said photosensitive drum to the main assembly when said process cartridge is mounted on the main assembly.    
     
     
         73 . 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 formed substantially at a center of said gear, said hole having a polygonal cross-section; 
 a cylinder having a photosensitive layer thereon;    a drive transmission member mounted to an end of said cylinder, said transmission member including: 
 a gear for transmitting driving force to said developing roller from said main assembly to said developing roller when said process cartridge is mounted to the main assembly;  
 a shaft provided substantially at a center of said gear;  
 a twisted projection provided at an end of said shaft, wherein said projection receives 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 gear;  
 a grounding contact for electrically grounding said photosensitive drum to the main assembly when said process cartridge is mounted on the main assembly.