Patent ID: 7505709

Claim:
An image forming apparatus, comprising: a developing cartridge engagement; a photosensitive drum cartridge engagement; and a process unit attachable to and detachable from the image forming apparatus, wherein the process unit includes a photosensitive drum cartridge and a developing cartridge, wherein said developing cartridge is equipped with: a developing roller that supplies developer to the photosensitive drum cartridge, a feed roller that supplies developer to the developing roller, a first protrusion element that engages said developing cartridge into a mounting position on said photosensitive drum cartridge, a second protrusion element that inhibits rotation of said developing cartridge about said first protrusion element by engaging said developing cartridge engagement when said process unit is in a process unit mounting position in said image forming apparatus, and a third protrusion element for inhibiting rotation of said photosensitive drum cartridge relative to said image forming apparatus when said process unit is in said process unit mounting position, wherein said first through third protrusion elements are provided on an exterior of two walls of said developing cartridge that support both ends of said developing roller rotatably in said developing cartridge, wherein said photosensitive drum cartridge is equipped with: a photosensitive drum, a fourth protrusion element located on an exterior of two walls of said photosensitive drum cartridge that support both ends of said photosensitive drum rotatably in said photosensitive drum cartridge, wherein said fourth protrusion element locks said photosensitive drum cartridge relative to said image forming apparatus by engaging said photosensitive drum cartridge engagement when said process unit is in said process unit mounting position, and a rotation inhibiting component that inhibits rotation of said photosensitive drum cartridge about said fourth protrusion element in relation to said image forming apparatus by engaging with the third protrusion element of said developing cartridge, and wherein the developing cartridge is attachable to and detachable from the photosensitive drum cartridge.