Patent ID: 7526227

Claim:
An image forming apparatus comprising: a belt unit including a looped belt that circularly moves, the looped belt having a first surface outside of the loop and a second surface inside of the loop, and being stretched to form a substantially straight portion on the loop that extends in a first direction; a plurality of photosensitive drums, each having a circumferential surface on which an electrostatic latent image is formable, each circumferential surface being opposed to the straight portion of the first surface; a plurality of developing units disposed in one-to-one correspondence with the plurality of photosensitive drums, wherein each developing unit provides the circumferential surface of the corresponding photosensitive drum with developer in order to form a visible image thereon; a transfer unit opposed to the straight portion of the second surface, wherein the transfer unit transfers the visible image from the photosensitive drum into either the first surface of the looped belt or a recording medium mounted on the first surface; a cartridge that holds the plurality of photosensitive drums; a body accommodating the belt unit, the plurality of photosensitive drums, the plurality of developing units and the transfer unit; a cartridge holding unit that holds the cartridge at a first predetermined position in the casing, wherein each circumferential surface of the plurality of photosensitive drums contacts the straight portion of the first surface when the cartridge is held by the cartridge holding unit at the first predetermined position; and a first guide unit that guides the cartridge into the first predetermined position, the first guide unit allowing the plurality of photosensitive drums to move apart from the straight portion of the first surface when the cartridge is detached from the first predetermined position, wherein the body has a base surface, wherein the plurality of photosensitive drums is arranged in the first direction and a line extending in the first direction is oblique to the base surface, wherein the first guide unit allows the cartridge to be pulled out from the body in a second direction substantially parallel to the base surface, and wherein the first guide unit prevents the plurality of photosensitive drums from sliding on the straight portion of the first surface, and further including a second guide unit, wherein the belt unit is detachably provided at a second predetermined position in the body and is guided into the second predetermined position in the body by second guide unit, wherein the second guide unit allows the straight portion of the first surface to move apart from the plurality of photosensitive drums when the belt unit is detached from the second predetermined position, wherein the second guide unit allows the belt unit to be pulled out from the body in a third direction opposite to the second direction substantially parallel to the base surface.