An image forming apparatus according to an example includes a main body, a driving coupler to drive a toner cartridge. The driving coupler is rotatable in a direction, a locking protrusion protrudes from an axial protrusion of the driving coupler in the direction of the driving shaft is lockable into a locking groove concavely formed in the direction of the driving shaft of a passive coupler of the toner cartridge. A driving force transmission surface of the axial protrusion of the driving coupler and a driving force receiving surface of the passive coupler are to contact each other to rotate the passive coupler in the direction.

Movement and/or urging of a developer carrying memer is carried out with high precision. A cartridge that is mountable to an apparatus main assembly of an image forming apparatus, the cartridge includes a developing roller; a frame supporting the developing roller; a movable part movably supported by the frame and movable to a first position and to a second position relative to the frame; and an elastic part provided between the frame and the movable part to urge the movable part. The movable part includes a first force receiving part that receives force from the apparatus main assembly, in a direction of moving from the first position to the second position, and a second force receiving part that receives force from the apparatus main assembly, in a direction of moving from the second position to the first position. When the movable part receives force from the apparatus main assembly at the first force receiving part and is at the second position, the movable part receives urging force from the elastic part in a direction of moving the movable part from the second position to the first position.

A process cartridge detachably mountable to an electrophotographic image forming apparatus including a main assembly side drive transmission member and a main assembly side urging member, the cartridge including a rotatable photosensitive drum; a rotatable developing roller for developing a latent image formed on the drum, the developing roller contactable to and spaceable from the drum; an urging force receiving portion for receiving an urging force from the urging member to space the roller from the drum; a cartridge side drive transmission portion capable of coupling with the main assembly side drive transmission member to receive a rotational force for rotating the roller; a releasing member capable of urging the main assembly side drive transmission member to decouple the cartridge side drive transmission member from the main assembly side drive transmission member by the urging force receiving portion receiving the urging force from the main assembly side urging member.

An electrophotographic image forming apparatus comprises a main assembly that includes moving force applying portion, a main assembly engaging portion having a driving shaft and a rotational force applying portion provided on the driving shaft, and an electrophotographic photosensitive drum. A cartridge is dismountable from the main assembly without dismounting the electrophotographic photosensitive drum from the main assembly. The cartridge includes a developing roller for developing a latent image formed on the electrophotographic photosensitive drum, a rotatable member for transmitting a rotational force to the developing roller, and a coupling member including a rotational force receiving portion engageable with the rotational force applying portion to receive a rotational force from the main assembly engaging portion, and a rotational force transmitting portion for transmitting the rotational force to the rotatable member. The cartridge also includes a frame including a moving force receiving portion that receives a moving force from the moving force applying portion, the frame supporting the developing roller and the rotatable member.

A coupling member is provided for a cartridge that includes a cylindrical photosensitive drum that is rotatable about an axis. The coupling member is operatively connected to the photosensitive drum and is capable of receiving a rotational force for rotating the photosensitive drum.

An image forming apparatus includes drum shafts supported by a main body, drum cartridges insertable and removable in an axial direction, a regulation side plate having bearings, a projecting portion provided to one of the regulation side plate and the main body, a fitting portion, and an urging force imparting portion. The urging force imparting portion is provided to the regulation side plate in an array direction of the bearings to impart an urging force that urges the regulation side plate toward the main body. At least a part of the urging force imparting portion is provided at a position for imparting the urging force on, with respect to the bearings, a side opposite to a position at which one of the projecting portion and the fitting portion is provided, in a direction orthogonal to the array direction of the bearings and the axial direction of each drum shaft.

Provided is an image forming apparatus, having: a power source; a first coupling member configured to be rotated by a driving force transferred from the power source; and a cartridge including a second coupling member configured to rotate in a state of being adsorbed to the first coupling member, and a rotating member connected with the second coupling member, wherein the first coupling member has a first driving force transfer surface which is perpendicular to a rotation axis of the first coupling member, the second coupling member has a second driving force transfer surface which is perpendicular to a rotation axis of the second coupling member, and the driving force is transferred from the first coupling member to the second coupling member in a state where an adsorption force is generated mutually between the first driving force transfer surface and the second driving force transfer surface.

In a developing cartridge, a first supporting member is attached to a housing and has a first developing supporting portion and a driving-force-receiving-member supporting portion, the first developing supporting portion being configured to rotatably support a first part of a rotational shaft, the driving-force-receiving-member supporting portion being configured to rotatably support a driving-force-receiving member. The second supporting member is attached to the housing and has a second developing supporting portion and a detection-rotational-body supporting portion, the second developing supporting portion being configured to rotatably support a second part of the rotational shaft, the detection-rotational-body supporting portion being configured to rotatably support a detection rotational body.

A process cartridge includes a photosensitive drum and a gear portion having gear teeth configured to receive a driving force from outside of the process cartridge. The gear portion includes an exposed portion exposed to outside of the process cartridge. A shortest distance from an axis of the photosensitive drum to a tooth tip of the exposed portion of the gear portion measured along a direction perpendicular to the axis of the photosensitive drum is no less than 90% and no more than 110% of a radius of the photosensitive drum.

A drum unit includes a photosensitive drum in a coupling member. The coupling member includes an engageable member having a driving force receiving portion which is capable of entering a recess of a driving shaft to receive a driving force for rotating photosensitive drum. The coupling member includes a holding member configured to hold said engageable member so as to be slidable at least in a radial direction of said drum unit.