A developing cartridge includes a casing, a developing roller rotatable about an axis extending in a first direction, a developing memory having an electrical contact surface, an agitator, an agitator gear rotatable about an agitator axis together with the agitator, a holder holding the electrical contact surface, and a plate movable between a first position and a second position in a second direction crossing the first direction relative to the casing. The holder is movable relative to the casing in a third direction crossing the first and second directions between a retracted position and an advancing position. The holder is movable from the retracted position to the advancing position in response to a movement of the plate from the first position to the second position. The plate is positioned farther away from the developing roller than the agitator gear and the holder are in the second direction.

There is provided an end member which is disposed in an end portion of a columnar rotating body mounted on an image forming apparatus main body, comprising: a tubular bearing member; and a shaft member held by the bearing member, in which the shaft member includes a rotating shaft which oscillates within a range of 18° or less with respect to a direction along an axis of the bearing member, a rotating force receiving member which is disposed in one end portion of the rotating shaft and is provided with an engaging member which is engaged with a driving shaft of the image forming apparatus main body, and a regulating member which is engaged with or disengaged from the rotating shaft or the rotating force receiving member by pressing, and switches a posture in which the engaging member is engaged with the driving shaft and a posture in which the engaging member is not engaged with the driving shaft.

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.

In a cartridge, a housing has a developer accommodating portion and includes a first side wall and a second side wall. A coupling member is disposed at a position opposite to the developer accommodating portion with respect to the first side wall. A detection body is disposed at a position opposite to the developer accommodating portion with respect to the second side wall. A first driving force transmission member is positioned at the same side with the coupling member with respect to the first side wall, and transmits driving force from the coupling member to a rotating member. A second driving force transmission member is positioned at the same side with the detection body with respect to the second side wall, and transmits driving force from the rotating member to the detection body.

An image forming apparatus includes a cartridge storage portion that is installed in an image forming apparatus main body, and a toner cartridge that is configured so as to be able to be inserted into and removed from the cartridge storage portion. The cartridge storage portion has a storage opening that receives the toner cartridge, and has a gap between an end part of the toner cartridge and the storage opening, through which the end part of the toner cartridge is not able to be held, when the toner cartridge is stored in the cartridge storage portion.

Provided is a technique for suppressing the occurrence of density non-uniformities in an image formed on a sheet. An image forming apparatus, which forms an image on a recording material by transmitting driving force to a cartridge, includes: a frame having a positioning portion which positions the cartridge by contacting the attached cartridge; a driving force transmission rotating body which transmits driving force by engaging with a driving force receiving portion of the driven unit; and a circumferential surface which is provided in one portion of the frame and rotatably supports the driving force transmission rotating body.

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.

In an image formation device, a driven gear is coupled to a far end portion in a unit inserting and withdrawing direction of a rotary fixing member or a rotary pressure member of a fixing unit. A driving gear is provided in a far end portion of a fixing unit housing part and engages with the driven gear when the fixing unit is housed in the fixing unit housing part. The driving gear and the driven gear are formed so that a transmission force transmitted from the driving gear to the driven gear in a mutual engagement position has a component so directed as to horizontally press the fixing unit against columns making a pair. The fixing unit as housed in the fixing unit housing part is pressed by the transmission force against the columns and positioned in a direction orthogonal to the unit inserting and withdrawing direction.

The image forming apparatus includes a drum cartridge having a photosensitive drum and a drum drive input member; a developing cartridge configured to be movably mounted to the drum cartridge, the developing cartridge comprising a developing roller disposed so as to face the photosensitive drum and a developing drive input member; a drum drive transmission member configured to engage with the drum drive input member and configured to transmit drum driving force to the drum drive input member while permitting a positional gap of the drum drive input member within a predetermined range; and a developing drive transmission member configured to engage with the developing drive input member and configured to transmit developing driving force to the developing drive input member while permitting a positional gap of the developing drive input member within a predetermined range.

A cartridge including a photosensitive drum, a cleaning unit that supports the photosensitive drum, a process member that acts on the photosensitive drum, the cartridge being detachable from a main body of the image forming apparatus in a rotational axial direction of the photosensitive drum. The cartridge further including a first position determination position determining a downstream position with respect to the main body in a mounting direction of the photosensitive drum, and a second position determination portion that determines an upstream position with respect to the main body in the mounting direction. Furthermore, in a cross section orthogonal to the mounting direction, a distance from an axis of rotation of the photosensitive drum to the second position determination portion in a predetermined direction is larger than a distance from the axis of rotation to the first position determination portion in the predetermined direction.