A power transmission apparatus includes a first pulley and a second pulley. A belt is extended around them. A supply unit supplies a voltage such that the first pulley and the belt are electrostatically attracted and that the second pulley and the belt are electrostatically attracted. The belt includes a conductor layer. At least one pulley includes a first electrode to which a first voltage is applied and a second electrode that is insulated from the first electrode and to which a second voltage is applied. An insulating layer or a dielectric layer is arranged between the conductor layer of the belt and the first electrode of the at least one pulley and an insulating layer or a dielectric layer is arranged between the conductor layer of the belt and the second electrode of the at least one pulley.

A sliding bearing is made of a resin and includes a tubular portion that includes an outer peripheral surface including a D-cut surface. A flange portion, which protrudes from the D-cut surface, is formed at one end portion of the tubular portion. An engagement portion is formed at the other end portion of the tubular portion. A protruding portion is formed on the outer peripheral surface of the tubular portion at a circumferential position that is outside a region in which the D-cut surface is formed and that is outside a region in which the engagement portion is formed.

A photoreceptor drum unit is provided with a cylindrical photoreceptor drum, and two end members which are respectively disposed at both ends of the photoreceptor drum in an axial direction. One of the end members is provided with an elastic member, is biased in the axial direction, and is extendable and contractable. The other of the end members is provided with a cylindrical bearing member and a shaft member held in the bearing member.

A drive transmission device includes an intermediate gear, a housing portion, and a support portion. The intermediate gear meshes with a first gear and a second gear to transmit a rotational driving force from the first gear to the second gear. The housing portion is formed from resin and includes a pair of cover portions, covering both sides of a gear train including the intermediate gear, to house the gear train. The support portion is formed from metal and supports the rotation shaft of the intermediate gear at a position outside the housing portion.

A photosensitive drum unit includes a photosensitive drum, a drum shaft, a resin frame, and a conducting member. The drum shaft is inserted through the photosensitive drum. The resin frame supports opposite ends of the drum shaft. The conducting member is a substantially coil-shaped spring member having a first end adjacent to the resin frame and a second end opposite to the first end. The conducting member is tapered from the first end toward the second end. The first end forms a first opening and the second end forms a second opening. A circle inscribed in the second opening has a diameter larger than an outer diameter of the drum shaft.

An image forming apparatus includes a transfer belt, a photoconductor drum, and a transmission member. The transfer belt includes a transfer surface. The photoconductor drum faces the transfer surface of the transfer belt in an attachment state where the photoconductor drum is attached to an apparatus main body. The transmission member is attached to a drum end of the photoconductor drum on the insertion direction side and transmits an input rotational driving force to the photoconductor drum. The transmission member includes a flange and a gear. The flange is larger than the photoconductor drum in outer diameter. The gear projects from the flange in the insertion direction with teeth being formed on an outer circumferential surface of the gear, the teeth receiving the rotational driving force. The gear is larger than the photoconductor drum and smaller than the flange in outer diameter.

To provide a structure for the process cartridge for receiving input of driving force from outside thereof.

The main assembly of the electrophotographic image forming apparatus includes a driving output member provided with an output gear portion and an output coupling portion. The process cartridge that can be mounted to and dismounted from the main assembly of the electrophotographic image forming apparatus includes a photosensitive member, an input coupling portion provided at the end of the photosensitive member and capable of coupling with the output coupling portion, and an input gear portion capable of meshing with the output gear portion.

A driving-force transmission member includes a coupling portion that includes a driving-force transmission surface and that transmits a driving force to a cartridge coupling, a first helical gear portion that engages with a driven gear of a cartridge to transmit the driving force, and a second helical gear portion that engages with a drive gear to receive the driving force. The portions rotate integrally with each other when the driving-force transmission member rotates about the axis of rotation. The driving-force transmission surface is shaped with a twist in the same direction as the driving-force transmission member. Helical teeth of the first helical gear portion are shaped with a twist in the same direction as the driving-force transmission surface. Helical teeth of the second helical gear portion are shaped with a twist in a direction opposite to the twist direction of the helical teeth of the first helical gear portion.

In a drive mechanism, a first engagement portion of a drive member includes a first contact portion capable of contacting with a second engagement portion in a case where a coupling member is at a first position and the drive member rotates in a first rotation direction, a second contact portion capable of contacting with the second engagement portion in a case where the coupling member is at a second position and the drive member rotates in the first rotation direction, and a third contact portion capable of contacting with the coupling member so as to regulate movement of the second engagement portion from the second position to the first position in a rotation axis direction when the coupling member is at the second position and the second contact portion and the coupling member are in a contact state by rotation of the drive member in the first rotation direction.

To develop a conventional coupling for transmitting a driving force.

A coupling member is provided with a supporting portion for movable supporting a driving force receiving portion for receiving a driving force.