An image forming unit insertable into an image forming apparatus includes a photosensitive drum and a drum case supporting the photosensitive drum. The drum case includes a guide configured to (i) at least partially engage with a solid head of the image forming apparatus when inserted into the image forming apparatus along a first direction and (ii) guide the solid head in a second direction orthogonal to the first direction when the solid head is selectively repositioned along the second direction toward the photosensitive drum.

An organic photoconductor includes a cylindrical body having a surface on which an electrostatic latent image is to be formed, and an optical tag provided on an outer circumferential surface of the cylindrical body. The organic photoconductor may be included in a development cartridge for an image forming apparatus.

A gear unit for transmitting a rotational force to a rotatable member carrying developer and to which a coupling member is mountable. The gear unit includes a hole portion which opens outwardly in a direction along a rotational axis of the cylinder gear and which has an opening capable of accommodating the spherical portion, a groove portion which continues from the hole portion and which is capable of accommodating the projected portion, and a limiting portion for limiting inward movement of the spherical portion in the direction along the rotational axis of the gear. A closing member is provided for partially covering the opening of the hole portion and mounted to the gear to limit outward movement of the spherical portion in the direction along the rotational axis of the gear. The closing member is constituted by a plurality of independent pieces.

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.

A printing drum mounting system and method of assembling the mounting system. The mounting system comprising a rotatable shaft; a first mount and a second mount arrangeable on the shaft to clamp a printing drum therebetween, wherein the first mount comprises a first engaging surface to form a mating contact with a corresponding first end surface of the printing drum and the second mount comprises a second engaging surface to form a mating contact with a corresponding end surface of the printing drum; a double-walled flexure to flexibly mount the first engaging surface and the shaft, the flexure to provide the first engaging surface with a single degree of freedom of axial movement relative to the shaft and to maintain mating contact between the first engaging surface and the first end surface of the printing drum as the printing drum thermally expands and contracts; and a releasable fixing to align and rigidly engage the second engaging surface relative to the shaft.

In a photosensitive drum, a drum flange is press-fitted to each end of a drum element tube. The drum flange includes a flange facing the drum element tube, and a press-in boss formed on a drum-facing surface side of the flange and press-fitted to the inner circumferential side of the drum element tube. The outer circumferential surface of the press-in boss is configured so that partial cylindrical surfaces to be in contact with the inner circumferential surface of the drum element tube and oppositely-facing partial cylindrical surfaces not to be in contact with the inner circumferential surface of the drum element tube are alternately formed along the circumferential direction. First openings formed to penetrate at least a part of the press-in boss are respectively provided on the proximal end side of the partial cylindrical surfaces in the press-in boss.

A process cartridge for use with a main assembly of an electrophotographic image forming apparatus, the main assembly including a driving shaft, to be driven by a motor, having a rotational force applying portion, wherein the process cartridge is dismountable from the main assembly in a direction substantially perpendicular to an axial direction of the driving shaft, the process cartridge includes i) an electrophotographic photosensitive drum having a photosensitive layer at a peripheral surface thereof, the electrophotographic photosensitive drum being rotatable about an axis thereof; ii) process means actable on the electrophotographic photosensitive drum; iii) a coupling member engageable with the rotational force applying portion to receive a rotational force for rotating the electrophotographic photosensitive drum, the coupling member being capable of taking a rotational force transmitting angular position for transmitting the rotational force for rotating the electrophotographic photosensitive drum to the electrophotographic photosensitive drum and a disengaging angular position in which the coupling member is inclined away from the axis of the electrophotographic photosensitive drum from the rotational force transmitting angular position, wherein when the process cartridge is dismounted from the main assembly of the electrophotographic image forming apparatus in a direction substantially perpendicular to the axis of the electrophotographic photosensitive drum, the coupling member moves from the rotational force transmitting angular position to the disengaging angular position.

A drum cartridge includes: a drum frame to which a developing cartridge is attachable; a photosensitive drum rotatable about an axis extending in a first direction; a memory having an electrical contact surface; and a resilient member positioned between the electrical contact surface and the drum frame. The resilient member is configured to expand and compress in a second direction crossing the electrical contact surface between a first state and a second state, the resilient member having a shorter length in the second state than in the first state. A distance between the drum frame and the electrical contact surface in the second direction when the resilient member is in the second state is smaller than a distance between the drum frame and the electrical contact surface in the second direction when the resilient member is in the first state.

An image forming apparatus includes a drum cartridge and developing cartridge. The drum cartridge may include a photosensitive drum rotatable about a first axis extending in an axial direction. The developing cartridge may include a developing roller rotatable about a second axis extending in the axial direction. The image forming apparatus may include a main casing including a slot extending in the axial direction. The image forming apparatus may include a first inner surface positioned inside of the slot, and a second inner surface positioned inside of the slot farther from the cover in the axial direction than the first inner surface from the cover in the axial direction. The first and second inner surfaces may be configured to press the developing roller toward the photosensitive drum.

An electrophotographic photoreceptor includes a cylindrical substrate; and a surface layer located on an outer surface of the cylindrical substrate. At least a substrate central portion in a cylindrical axial direction of the outer surface of the cylindrical substrate is formed as a rough surface, and a surface roughness of a surface-layer central portion in the cylindrical axial direction of an outer surface of the surface layer is larger than that of at least one of two surface-layer end portions in the cylindrical axial direction of the outer surface of the surface layer. An image forming apparatus includes the electrophotographic photoreceptor; and a peripheral member capable of contacting a surface of the electrophotographic photoreceptor.