Patent ID: 8903280

Claim:
An image forming apparatus comprising: a drum unit comprising a photosensitive drum; a developing unit comprising: a developing roller disposed so as to face the photosensitive drum; and a developing drive input member, which is rotatable, and which is configured to receive developing driving force for rotating the developing roller, the developing unit configured to move between a first position in which the developing roller is in contact with the photosensitive drum and a second position in which the developing roller is spaced apart from the photosensitive drum; and a developing drive transmission member that is configured to detachably engage with the developing drive input member and configured to transmit the developing driving force to the developing drive input member, wherein a rotational center of the developing drive input member is substantially coincident with a rotational center of the developing drive transmission member, wherein the developing drive input member comprises a developing driving force receiving surface, which the developing drive transmission member is configured to contact, so as to receive the developing driving force from the developing drive transmission member, and wherein the developing driving force receiving surface is disposed on a straight line which passes through the rotational center of the developing drive input member.