A development unit includes an attachable unit and an attached unit. The attachable unit includes an engaging section. The attached unit includes an engaged section that allows the engaging section to be brought into engagement with the engaged section attachably and detachably, and whose state changes in response to the engagement of the engaging section. The state of the engaged section upon the engagement of the engaging section is maintained even after the engaging section is detached from the engaged section.

A developing cartridge may include a housing including an outer surface, a small-diameter gear, a large-diameter gear, a first gear, and a moving member. The small-diameter gear may include a first engaging portion positioned on at least a portion of a peripheral surface of the small-diameter gear. The large-diameter gear may be positioned farther from the outer surface than the small-diameter gear from the outer surface. The large-diameter gear may be rotatable together with the small-diameter gear. The first gear may include a second engaging portion, a first end surface, a second end surface, and at least one protrusion. The moving member may include a contact portion configured to move the moving member from one position to another position in a state where the contact portion is in contact with the protrusion.

A developer cartridge includes a first gear rotatable about a first axis extending in an axial direction, and a second gear rotatable in a rotation direction about a second axis extending in the axial direction. The second gear includes: an engagement portion engageable with gear teeth of the first gear; a first protrusion and a second protrusion protruding in the axial direction. The first and second protrusions extend to be spaced apart from each other in the rotation direction. The first protrusion has first end and a second end defining a first angle therebetween about the second axis. The second protrusion has a third end and a fourth end farther away from the first protrusion than the third end is in the rotation direction. The second end and the third end define a second angle therebetween about the second axis. The first angle is smaller than the second angle.

An image forming apparatus includes an attachment part to which a toner container is detachably attached. The toner container has a main body and a non-compatible shape discriminating piece. In the main body, a toner is contained. The non-compatible shaped piece is capable of being assembled into the main body and has a shape different for each kind of the toner container. The attachment part has a non-compatible shape discriminating member capable of engaging with the non-compatible shaped piece.

An image forming apparatus includes: a first guide that is provided in an apparatus housing and configured to suspend and hold a first unit including an image holder so that the first unit is movable in an insertion and removal direction; a second guide that is provided in the apparatus housing and configured to suspend and hold a second unit including a developer holder so that the second unit is movable in an insertion and removal direction; and a pedestal that is disposed on a front side in the insertion and removal direction with respect to the first guide and the second guide, supports, from below in a gravity direction, the first unit and the second unit while the first unit and the second unit are inserted into the apparatus housing, and does not contact with the first unit and the second unit located in the apparatus housing.

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 developer container includes a memory device with a first marker; and a main body with a second marker, the main body being configured to accommodate a developer. The memory device is attached to the main body such that both the first marker and the second marker are visually recognized.

A developing cartridge includes: a first gear; a second gear; a gear cover; and a protrusion. The first gear is rotatable about a first axis extending in a predetermined direction. The first gear is movable from a first position to a second position. The second gear is rotatable about a second axis extending in the predetermined direction upon receipt of a drive force from the first gear. The gear cover has an opening and covers at least a portion of the second gear. The protrusion extends in the predetermined direction. The protrusion is movable with the rotation of the second gear while the first gear moves from the first position to the second position. The protrusion is further movable past the opening at least once after the protrusion moves past the opening once, while the protrusion moves with the rotation of the second gear.

A developing cartridge includes: a casing configured to store developer; a developing roller configured to rotate about a first axis extending in a first direction; a shaft provided at one end of the casing in the first direction; and an electrode configured to rotate about the shaft and supply power to the developing roller. The shaft extends in the first direction and has a peripheral surface. The electrode has a first protrusion configured to rotate together with the electrode, the first protrusion extending along a portion of the peripheral surface of the shaft.

A cartridge includes a detection gear and a memory. The detection gear may be rotatable about a first axis extending in a predetermined direction. The detection gear may include a first protrusion movable with rotation of the detection gear. The memory may include a first storage region configured to store, based on the motion of the first protrusion, new product determination information representing that the cartridge is detected as a new product.