Patent ID: 8406657

Claim:
A color electrophotographic image forming apparatus for forming a color image on a recording material, said apparatus comprising: an image forming unit rotatable relative to a main assembly of said apparatus, said image forming unit including: a plurality of mounting portions for demountably mounting cartridges each provided with a developing member for developing an electrostatic latent image formed on an electrophotographic photosensitive member drum with a developer; a transfer member for transferring the developed image onto the recording material, wherein said image forming unit is rotatable between a transfer position for transferring the developed image from said transfer member onto the recording material, and a mounting and demounting position, different from the transfer position, for mounting and demounting said cartridges relative to respective said mounting portions in a state in which said cartridges which contain different color developers are mounted to respective said mounting portions; and a grip portion usable for rotating said image forming unit between the transfer position and the mounting and demounting position, wherein said main assembly of said apparatus includes a regulating portion engageable with a portion to be regulated provided on said image forming unit, wherein said image forming unit is maintained at the mounting and demounting position by engagement between said regulating portion and said portion to be regulated, wherein said portion-to-be-regulated is provided with a tapered surface inclined in a rotating direction of said image forming unit, wherein said regulating portion is provided with a tapered surface inclined in the rotating direction and contactable with the tapered surface of said portion-to-be-regulated, wherein in a state that said image forming unit is at the mounting and demounting position after movement from the transfer position while said grip portion is gripped, said regulating portion is engaged with said portion-to-be-regulated by an elastic force of an elastic member, and wherein when said image forming unit is rotated from the mounting and demounting position towards the transfer position while said grip portion is gripped, said regulating portion is disengaged from said portion-to-be-regulated against an elastic force in interrelation with a rotation of said image forming unit to permit movement of said image forming unit towards the transfer position.