A photo-interruptor unit includes a photo-interruptor and a supporting portion to detachably support the photo-interruptor. The supporting portion includes a hole which is formed on an attaching surface and through which a hook portion is inserted, and a guide portion to protrude from the attaching surface and guide the hook portion so that it deforms in a deformation direction when the photo-interruptor is moved in a movement direction intersecting an insertion direction. A regulating portion protrudes from the attaching surface and forms continuously with the guide portion to regulate a position in the movement direction of the photo-interruptor. The guide portion includes a first rib portion and a second rib portion that oppose one another in the deformation direction, and a distance between the first rib portion and the second rib portion in the deformation direction narrows toward a downstream direction of the movement direction.

A driving force transmission mechanism is a mechanism for transmitting rotational force of the second rotor having a driving-side coupling to a first rotor having a driven-side coupling. The driving-side coupling includes a body and a plurality of second engaging members engaging with first engaging members of the driven-side coupling, each of the plurality of second engaging members has at an abutting point on an abutting surface of a corresponding first engaging member a first inclined surface inclined so as to be away from a rotation axis of the body from a downstream side toward an upstream side in a rotation direction of the body.

An image forming apparatus, having a first photosensitive drum, a first developing roller, a first shifting member movable between a contacting position and a separating position, a motor, a first joint, a first clutch operable in one of a transmittable condition and a discontinuing condition, a first shifting cam rotatable between a first position, in which the first shifting cam locates the first shifting member at the contacting position, and a second position, in which the first shifting cam locates the first shifting member at the separating position, and a first switching cam rotatable between a third position, in which the first switching cam places the first clutch in the transmittable condition, and a fourth position, in which the first switching cam places the first clutch in the discontinuing condition, alongside the first shifting cam rotating between the first position and the second position, is provided.

An image forming apparatus includes a main housing, a drawer, and a drum unit. The drawer is movable between an accommodated position at which the drawer is accommodated in the main housing and a pulled-out position at which the drawer is pulled out from the main housing. The drum unit is attachable to the drawer in a state where the drawer is located at the pulled-out position. The drum unit includes a first photosensitive drum, a second photosensitive drum, and a waste toner pipe allowing passage of waste toner from the first photosensitive drum and waste toner from the second photosensitive drum.

A replaceable unit includes a rotatable gear positioned on a housing of the replaceable unit and an encoded member encoded with identifying information of the replaceable unit. The encoded member is positioned on an axially outboard face of the gear such that the encoded member is rotatable with the gear for communicating the identifying information of the replaceable unit to a sensor of an image forming device when the replaceable unit is installed in the image forming device. The encoded member is configured to move axially outward relative to a rotational axis of the gear upon rotation of the gear in a first rotational direction for communicating the identifying information of the replaceable unit to the sensor. The encoded member is configured to move axially inward relative to the rotational axis of the gear upon rotation of the gear in a second rotational direction opposite the first rotational direction.

An image forming apparatus includes: a main body casing having an opening; a cover movable between a closing position to close the opening and an opening position to open the opening; and a process cartridge detachably attachable to the main body casing through the opening while the cover is at the opening position. The process cartridge includes: a photosensitive drum; a developing device; a toner receiving part; and a toner conveying part. The toner receiving part has a first end portion and a second end portion. The first end portion has a receiving opening for receiving toner. When the cover is at the closing position and the process cartridge is in the attached state, the first end portion is outside the main body casing while the second end portion is inside the main body casing. The toner conveying part conveys toner in the toner receiving part to the developing device.

An image forming apparatus includes a photosensitive drum, a photoreceptor housing, a developing roller, a development housing, first contact members and second contact members. The first contact members are provided in end portions of the photoreceptor housing in an axial direction of the photosensitive drum. The second contact members are provided in end portions of the development housing in the axial direction, and come into contact with the first contact members by a force in which the development housing is pushed toward the photoreceptor housing. A position of at least one of the first contact member and the second contact member can be adjusted in a direction in which the first contact member and the second contact member come close to each other or separate away from each other.

Provided is a processing cartridge detachably installed in an imaging device. The processing cartridge includes a first unit and a second unit, and a movable assembly coupled to and receive force from the force applying portion. When the processing cartridge is assembled to the imaging device, the first t and second units can be switched between states of approaching and separating. The movable assembly comprises an installing part and an acting part movable relative to and connectable with each other. The movable assembly is installed in the processing cartridge by the installing part, the acting part is coupled to the force applying portion and receives force from the force applying portion, to force the first and second units to switch between the two states. The acting part is retractable relative to the installing part and comprises an acting block and a guide block guided by the installing part.

An image forming apparatus includes: an image carrier body to be transported; an image forming unit that forms an image on the image carrier body; a change roller that is in contact with an inner peripheral surface of the image carrier body so as to be rotatable around a rotation axis and that is capable of changing an angle of the rotation axis with respect to a width direction of the image carrier body; a flywheel provided at the change roller; and a driving mechanism that applies a driving force for changing an angle of the rotation axis with respect to the width direction to an applied portion that moves together with the change roller. A direction of the driving force applied to the applied portion by the driving mechanism is opposite to a direction in which the applied portion moves due to gravity acting on the flywheel.

A developing cartridge may include: a casing for accommodating developer therein; a developing roller rotatable about an axis extending in a first direction and positioned at one side of the casing in a second direction; a storage medium having an electric contact surface; and a holder movable relative to the casing in the second direction with the electric contact surface between a first position and a second position, the holder having an outer surface at which the electric contact surface is positioned.