A first cartridge support is configured to support a drum cartridge. The first cartridge support is configured to move in a first direction between a first position at which the drum cartridge is mounted on a housing and a second position at which the drum cartridge is detachable. A second cartridge support is configured to support a development cartridge. The second cartridge support is configured to move in the first direction between a third position at which the development cartridge is mounted on the drum cartridge and a fourth position at which the development cartridge is detachable. In a state where the second cartridge support is located at the third position, the second cartridge support is located between the first cartridge support located at the first position and a cover located at a closed position with respect to the first direction.

Provided is an image formation device including a photoreceptor configured to carry a toner image and a developer configured to form the toner image on a surface of the photoreceptor and configured such that the developer is a replaceable development unit, the image formation device including: a development bias application section configured to apply a development bias to between the photoreceptor and the developer; a stabilization control section configured to perform image stabilization control of determining a development bias value to be used in future by changing the development bias while measuring a density of the toner image formed by the developer, thereby obtaining the toner image with a target density; and a life determination section configured to determine expiration of use of the development unit when the development bias value determined by the stabilization control falls outside a preset acceptable range.

A process cartridge having a drum cartridge and a toner cartridge is provided. The drum cartridge includes a photosensitive drum, a cleaner, a conveyer tube, a developing roller, and a developing device. The toner cartridge is attachable to the drum cartridge and is located on a side of the developing roller opposite to the photosensitive drum in an attaching direction. The toner cartridge includes a waste toner container to store the toner conveyed through the conveyer tube and a toner container to store the toner to be supplied to the photosensitive drum. The toner container communicates with a developing chamber in the developing device and is located at least partly between the waste toner container and the developing chamber. The conveyer tube extends in the attaching direction and is arranged to overlap the photosensitive drum, the toner container, and the waste toner container in a view along an axial direction.

A process cartridge having a drum cartridge and a toner cartridge is provided. The drum cartridge includes a photosensitive drum, a cleaner, a conveyer tube, a developing roller, and a developing device. The toner cartridge is attachable to the drum cartridge and is located on a side of the developing roller opposite to the photosensitive drum in an attaching direction. The toner cartridge includes a waste toner container to store the toner conveyed through the conveyer tube and a toner container to store the toner to be supplied to the photosensitive drum. The toner container communicates with a developing chamber in the developing device and is located at least partly between the waste toner container and the developing chamber. The conveyer tube extends in the attaching direction and is arranged to overlap the photosensitive drum, the toner container, and the waste toner container in a view along an axial direction.

An image forming apparatus is provided. The image forming apparatus includes a chassis having an opening, a cover, photosensitive members, an intermediate transfer belt, a primary-transfer member, a secondary-transfer roller, a cleaner device, an external-sheet inlet, a waste toner container, a connector, and a conveying roller, which is arranged within the feeding path to feed the recording sheet inserted through the external-sheet inlet in the feeding path. The conveying roller is mounted on the waste toner container and removable from the chassis along with the waste toner container.

A cleaning device includes: a plate-like cleaning member that cleans a cleaning target surface, which is moved with toner attached thereto, of a cleaning target body by scraping the toner with a part of a distal end surface of the cleaning member contacting the cleaning target surface; a body that has a storage space that stores waste toner that has fallen after being scraped by the cleaning member; and a transport member disposed in the storage space of the body at a position below the distal end surface of the cleaning member to transport the waste toner stored in the storage space along a longitudinal direction of the cleaning member. The transport member includes a non-transport portion that exerts no transport force in a direction along the longitudinal direction of the cleaning member.

A cleaning device includes: a plate-like cleaning member that cleans a cleaning target surface, which is moved with toner attached thereto, of a cleaning target body by scraping the toner with a part of a distal end surface of the cleaning member contacting the cleaning target surface; a body that has a storage space that stores waste toner that has fallen after being scraped by the cleaning member; and a transport member disposed in the storage space of the body at a position below the distal end surface of the cleaning member to transport the waste toner stored in the storage space along a longitudinal direction of the cleaning member. The transport member includes a non-transport portion that exerts no transport force in a direction along the longitudinal direction of the cleaning member.

A developer storage device that stores developer includes a frame having an internal space and an inlet, a partition portion for partitioning the internal space into first and second chambers, the partition portion including a communication port through which the first and second chamber communicate, a conveyance portion arranged in the internal space and configured to convey the developer, and a detection unit detecting an amount of the developer stored in the first chamber. When the amount of the developer in the first chamber is less than a predetermined value, the developer is conveyed to a far side portion of the first chamber by the conveyance portion. When the detection unit detects that the amount of the developer in the first chamber reaches the predetermined value or more, the conveyance portion conveys the developer to the second chamber.

A channel switching device includes: an accommodation portion in which a unit is detachably accommodated; a first channel; a second channel passing through the accommodation portion; and a switch separating the first channel and the second channel, the switch including: a first communication portion communicating with the first channel and the second channel; and a second communication portion disposed at a different position with the first communication portion, the second communication portion communicating with the first channel and the second channel, and the switch configured to switch to one of the first communication portion or the second communication portion in response to an attachment or detachment of the unit to the accommodation portion.

An image forming apparatus includes a first collecting container provided detachably and configured to collect residual toner discharged from an image forming portion, a second collecting container provided detachably and configured to collect the residual toner discharged from the image forming portion, and a feeding device to feed the residual toner, discharged from the image forming portion, toward the first collecting container and the second collecting container selectively. The first collecting container and the second collecting container are provided below an intermediary transfer belt and disposed side by side in a widthwise direction perpendicular to a rotational axis direction of an image bearing member, and at least a part of the first collecting container overlaps with the intermediary transfer belt as viewed in the vertical direction, and at least a part of the second collecting container overlaps with the intermediary transfer belt as viewed in the vertical direction.