A developing cartridge includes: a casing, a developing roller, a storage medium having an electrical contact surface, a holder, and a holder cover configured to cover the holder. The holder has: a first outer surface holding the electrical contact surface, a second outer surface spaced away from the first outer surface in a third direction, and a resilient member connected to the first outer surface and to the second outer surface. The resilient member is configured to expand and contract to change a distance between the first outer surface and the second outer surface. The resilient member has a first length in the third direction in a state where the holder cover is detached from the holder. The resilient member has a second length in the third direction smaller than the first length in a state where the holder cover is attached to the holder.

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.

A process cartridge includes a drum cartridge that has a drum frame having a a second end portion spaced apart from a first end portion in a first direction and a fourth end portion spaced apart from a third end portion in a second direction, a photosensitive drum rotatable about a first axis extending in the second direction and positioned at the first end portion of the drum frame, and a first storage medium that includes a first electrical contact surface. A developing cartridge is detachably attachable to the drum frame and has a developing roller that is rotatable about a second axis extending in the second direction and a second storage medium including a second electrical contact surface. The first electrical contact surface is positioned closer to the second end portion of the drum frame than the photosensitive drum is to the second end portion of the drum frame in the first direction, and in a state where the developing cartridge is attached to the drum cartridge, the second electrical contact surface is positioned closer to the second end portion of the drum frame than the photosensitive drum is to the second end portion of the drum frame in the first direction.

A toner container includes a container body, an opening, a cover, a toner discharge port, a shutter, a cylindrical structure, protrusions, and an identifier. The shutter is attached to the cover and includes a main shutter covering the toner discharge port. The main shutter moves between a closed position to close the toner discharge port and an open position to open the toner discharge port. The protrusions are on both sides of the cover and protrude in a direction orthogonal to a toner container mounting direction. The identifier is on the cover to indicate a toner color. The cylindrical structure's leading end is downstream of leading ends of the protrusions in the mounting direction. The main shutter's leading end is downstream of the protrusions' leading ends in the mounting direction when the main shutter is in the closed position. The protrusions are downstream of the identifier in the mounting direction.

An image forming apparatus includes a mounting unit, a restricting member, a driving source, a reading unit, a storage unit, and a control unit. The reading unit reads mounting-destination information from a storage medium. The mounting-destination information is information stored in the storage medium located in the container and information assigned to the image forming apparatus used by an ordering source user who has ordered the container. The own-apparatus information is information assigned to its own apparatus. The control unit that determines whether the mounting-destination information read from the storage medium of the container mounted to the mounting unit by the reading unit matches the own-apparatus information or not when the container is mounted to the mounting unit, and the control unit controlling driving of the driving source to move the restricting member to a restriction position when the mounting-destination information matches the own-apparatus information.

A sheet processing apparatus according to an embodiment includes an image reading unit that reads an image of a sheet. A sheet discharge tray receives a sheet read by the image reading unit. A measurement unit measures a total weight of sheets on the sheet discharge tray. A read counter counts a number of all sheets read by the image reading unit. The read counter stores the number of the currently read sheet in association with the measured total weight of the sheets on the sheet discharge tray. A measured value comparison unit compares the current measured weight of the sheets and a stored measured weight stored in association with the number of the read sheet immediately preceding the currently read sheet. A dropped page identification unit identifies, by page number, one or more sheets dropped from the sheet discharge unit based on the comparison result.

A developing cartridge includes a storage medium and a holder. The developing cartridge may be configured to move from a first position to a second position and further from the second position to a third position. The holder may include a first outer surface, a second outer surface, and an engaging portion. The second outer surface may have a guide surface out of contact with part of an image forming apparatus in a case where the developing cartridge is at the first position. The guide surface may contact with the part of the image forming apparatus in a case where the developing cartridge is at the second position. The engaging portion may be configured to allow the holder to engage with the image forming apparatus in a state where an electric contact surface contacts with an electric connector in a case where the developing cartridge is at the third position.

A drum cartridge includes: a drum frame to which a developing cartridge is attachable; a photosensitive drum; and a first storage medium. The drum frame has one end portion and another end portion spaced apart from the one end portion in a first direction. The photosensitive drum is rotatable about a first axis extending in a second direction and is positioned at the one end portion of the drum cartridge. The first storage medium includes a first electrical contact surface. The first storage medium is positioned at an outer surface of the drum frame, the outer surface being exposed in a state where the developing cartridge is attached to the drum frame.

An image forming apparatus includes a mounting unit, a restricting member, a driving source, a reading unit, a storage unit, and a control unit. The reading unit reads mounting-destination information from a storage medium. The mounting-destination information is information stored in the storage medium located in the container and information assigned to the image forming apparatus used by an ordering source user who has ordered the container. The own-apparatus information is information assigned to its own apparatus. The control unit that determines whether the mounting-destination information read from the storage medium of the container mounted to the mounting unit by the reading unit matches the own-apparatus information or not when the container is mounted to the mounting unit, and the control unit controlling driving of the driving source to move the restricting member to a restriction position when the mounting-destination information matches the own-apparatus information.

An information storage device installed in a removable device configured to be removably installed in an image forming apparatus body, includes: an information storage unit that stores information communicated between the image forming apparatus body and the removable device; a terminal that comes in contact with a body side terminal; and a substrate that holds the information storage unit and the terminal and includes a hole configured to be engaged with a protruding section installed in the image forming apparatus body. The terminal includes a plurality of terminals each including one of a plurality of metallic plates arranged in a transverse direction thereof. An earth terminal, which comes in contact with a body side earth terminal formed in the protruding section, is formed in the hole. The hole is disposed at a position sandwiched between two metallic plates among the plurality of metallic plates.