Disclosed is a developing apparatus including: a developer bearing member that bears a developer; a developing frame body that rotatably supports the developer bearing member; a one-end side end member that supports one-end side in an axis direction of the developer bearing member of the developing frame body; and another-end side end member that supports the other-end side in the axis direction of the developer bearing member of the developing frame body. Each of the one-end side end member and the other-end side end member is independently movable with respect to the developing frame body.

Movement and/or urging of a developer carrying member 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 developing roller is located nearer a first end than a second end in a first direction. A first boss extends in a second direction and is movable together with a housing. The first boss bears the weight of a developer cartridge when the first boss is supported by a support surface of a first side plate of a drum unit, and is located away from the developing roller in the first direction and the third direction. A first pressure receiving surface is located farther away from the developing roller than the first boss in the third direction. The pressure receiving member receives a pressing force in the third direction from a pressing member of the first side plate of the drum unit. The first boss is located away from the developing roller in the first direction by a first distance. The first pressure receiving surface is located away from the developing roller in the first direction by the first distance or by a second distance smaller than the first distance.

A developing cartridge includes: a developing roller; a casing having an outer surface; a first shaft rotatable about a rotational axis; a first arm; and a cam. The first arm and the cam extend radially outward from an outer periphery of the first shaft and pivotally movable along with rotation of the first shaft. The cam has: one end connected to the first shaft; another end positioned farther from the rotational axis than the one end is farther from the rotational axis; and a pressure contact surface inclined so as to approach the outer surface of the casing as extending from the one end toward the another end. When a pressing force is applied to the pressure contact surface, the first arm pivotally moves from a first position to a second position along with: pivotal movement of the cam; and the rotation of the first shaft.

A cartridge and a drum unit include a drum flange provided at one end portion of a photosensitive drum and a coupling member operatively connected to the drum flange, with the coupling member being configured to transmit a driving force to the drum flange. A coil spring urges the coupling member. At least a part of the coil spring surrounds at least a part of a shaft portion of the coupling member. An extent of the coil spring that surrounds the shaft portion and an extent of the shaft portion that is surrounded by the coil spring are positioned within a hollow interior portion of the drum flange.

One of two walls apart from each other in a first direction has an opening. A drum cartridge includes a photosensitive drum rotatable about a drum axis extending in the first direction when the drum cartridge is attached to a housing. The drum cartridge is movable through the opening between a first position at which an entirety of the drum cartridge is located inside the housing and a second position at which at least part of the drum cartridge is located outside the housing. The development cartridge includes a development roller rotatable about an axis extending in the first direction. The development cartridge is unattachable to and undetachable from the drum cartridge in a state where the drum cartridge is located at the first position. The development cartridge is attachable to and detachable from the drum cartridge in a state where the drum cartridge is located at the second position.

A cartridge including: a first unit including an image bearing member and a first portion, and configured to take a removal posture when the cartridge is to be removed from a main body; a second unit including a developer bearing member and a second portion, the second unit being movable between a first position where the developer bearing member is in contact with the image bearing member and a second position where the developer bearing member is separated from the image bearing member and where the second portion is in contact with the first portion, wherein when the first unit takes the removal posture, the second unit is located at the second position, and when the second unit is located at the second position, movement of the second unit in a direction, in which the developer bearing member is separated from the image bearing member, is restricted.

A cartridge includes a developing roller, a downstream side drive transmission member, an upstream side drive transmission member, an elastic member for urging the downstream side drive transmission member toward a blocked position from a transmission position, and a maintaining member for maintaining the downstream side drive transmission member in the transmission position against an elastic force of the elastic member. The downstream side drive transmission member is coupled to the upstream side transmission member when the downstream side drive transmission member is in the transmission position, and the downstream side drive transmission member is not coupled to the upstream side transmission member when the downstream side drive transmission member is in the blocked position.

A developing cartridge includes a casing having an outer surface, a developing roller, a first electrode, and a boss. The developing roller is movable together with the casing and includes a developing roller shaft extending along a first axis extending in a first direction. The developing roller is rotatable about the first axis. The first electrode is positioned at one end portion in the first direction of the developing roller shaft, and electrically connected to the developing roller shaft. The boss is positioned at one end portion in the first direction of the outer surface. The boss extends in the first direction and is engageable with the drum unit. A part of the first electrode is configured to contact with a second electrode of the drum unit as a result of pivotal movement of the developing cartridge about the boss relative to the drum unit.

An image forming apparatus includes a housing and a first process cartridge. The first process cartridge is attachable to and detachable from the housing. The first process cartridge includes a first photosensitive drum, a first developing roller, and a developing frame. The developing frame has a toner inlet opening. The toner cartridge has a toner supply opening. The toner cartridge is positioned above the developing frame such that the toner supply opening and the toner inlet opening face with each other in upward/downward direction. In the state where the first process cartridge to which the toner cartridge is attached is attached to the housing, the toner cartridge is incapable of being detached from the first process cartridge. In a state where the first process cartridge to which the toner cartridge is attached is detached from the housing, the toner cartridge is detachable from the first process cartridge.