Patent ID: 8280279

Claim:
An image forming apparatus for forming an image on a recording material, wherein a process cartridge including a photosensitive drum and process device actable on the photosensitive drum is detachably mountable to a main assembly of said image forming apparatus in a direction of an axis of the photosensitive drum, said image forming apparatus comprising: a first positioning portion; a second positioning portion; a main assembly coupling; and a supporting member, wherein said first positioning portion is provided above the process cartridge when the process cartridge is mounted to said main assembly, wherein said first positioning portion positions with respect to a direction crossing the axis of the photosensitive drum, the photosensitive drum at a position upstream of said second positioning portion with respect to a mounting direction in which the process cartridge is mounted to said main assembly of said apparatus, wherein said second positioning portion is provided above the process cartridge when the process cartridge is mounted to said main assembly, wherein said second positioning portion is positioned downstream of said first positioning portion with respect to the mounting direction and positions the photosensitive drum with respect to a direction crossing the axis of said photosensitive drum, wherein said main assembly coupling is provided downstream of said first positioning portion with respect to the mounting direction, and engages a drum coupling provided at an end of the photosensitive drum to transmit a driving force to the photosensitive drum when the process cartridge is mounted to said main assembly, and wherein said supporting member supports the process cartridge at a first position that positions the photosensitive drum to contact said first positioning portion and said second positioning portion and at a second position that spaces the photosensitive drum away from said first positioning portion and said second positioning portion to permit mounting and dismounting of the process cartridge relative to said main assembly of said apparatus, said supporting member including a guide portion that engages a portion-to-be-guided provided at a bottom portion of the process cartridge to guide the process cartridge along the mounting direction, and a third positioning portion that limits rotation of the process cartridge relative to said first positioning portion and said second positioning portion when said main assembly coupling transmits a driving force to the drum coupling and that positions the bottom portion of the process cartridge at a position upstream of said second positioning portion with respect to the mounting direction.