An image forming apparatus includes a developer container to and from which a replenishment container is attachable and detachable, the developer container including an accommodating portion, and a supporting portion, wherein the developer container includes a projection portion that is provided at one end portion thereof in the rotation axis direction of the developer bearing member and projects toward the supporting portion more than a center portion of the developer container in a crossing direction crossing the rotation axis direction, the projection portion communicates with the accommodating portion and includes, at a distal end portion thereof, an attachment portion configured such that the replenishment container is attachable thereto in a state of being exposed to the outside of the apparatus, and a replenishment port for replenishing the accommodating portion with developer from the replenishment container is defined in the attachment portion.

An image forming apparatus includes: a main casing; a toner cartridge including a toner casing having a toner outlet for discharging toner in the toner cartridge and a toner shutter for opening and closing the toner outlet; a drum cartridge including a photosensitive drum and a developing unit including a developing casing having a toner inlet for receiving the toner from the toner cartridge, a developing shutter for opening and closing the toner inlet, and a cushion member positioned between the developing casing and the developing shutter. When the developing casing is moved relative to the photosensitive drum while the drum cartridge and the toner cartridge are attached to the main casing, the developing shutter opens the toner inlet, and the toner shutter opens the toner outlet, the cushion member allows movement of the developing casing relative to the developing shutter while the developing shutter engages with the toner cartridge.

An image forming apparatus cartridge includes a coupling member having an axis about which the coupling member is rotatable. The coupling member includes a first end portion operatively connected to a developer roller and a developer supplying roller and a second end portion for receiving a rotational force. The coupling member is movable between a first position in which the axis of the coupling member is substantially parallel to and offset from the axis of the developer roller, a second position in which the axis of the coupling member is inclined with respect to the position of the axis when the coupling member is in the first position, and a third position in which the axis of the coupling member is inclined with respect to the position of the axis when the coupling member is in the first position in a direction opposite to the direction the coupling member is inclined when in the second position.

A developing cartridge includes a casing, a drive gear, a first gear, and a second gear rotatable relative to the first gear. The drive gear includes a small-diameter gear part, and a large-diameter gear part. The first gear includes: a first gear teeth part having a plurality of gear teeth; and a first protrusion movable in accordance with rotation of the first gear teeth part. The second gear includes: a second gear teeth part having at least one gear tooth; and a second protrusion movable in accordance with rotation of the second gear teeth part. The second gear teeth part is configured to meshingly engage with the large-diameter gear part to rotate the second gear after the first gear rotates by a prescribed angle by meshing engagement between the small-diameter gear part and the first gear teeth part.

Provided is an image forming unit including a photosensitive unit including an image bearing member, a developing unit including a developer bearing member and a container capable of containing a developer, a rotation shaft, the developing unit being rotated around the rotation shaft and positioned at one of a development position where the developer bearing member supplies the developer to the image bearing member and a separation position where the developer bearing member separates from the image bearing member, and a sensing portion sensing a variation or an amount corresponding to an amount of the developer contained in the developing unit. When the developing unit is at the separation position, the sensing portion restricts the rotation of the developing unit thereby receiving a force from the developing unit.

An image forming device, including: a housing; a drawer movable between an inside position at which the drawer is located inside the housing and an outside position at which the drawer is located outside the housing; a drum cartridge including a photoconductive drum and a developer roller and mountable on the drawer; a toner cartridge storing toner to be supplied to the developer roller and mountable on the drawer, wherein the drawer includes a first guide that guides the toner cartridge in mounting the toner cartridge on the drawer, and wherein the drum cartridge includes a second guide connected to the first guide in a state in which the drum cartridge is mounted on the drawer, the second guide being configured to guide the toner cartridge in mounting the toner cartridge on the drawer in the state in which the drum cartridge is mounted on the drawer.

A print material cartridge may include a hopper to maintain an amount of print material therein; and an atmospheric pressure seal to seal the hopper from atmosphere; wherein a pressure within the hopper and sealed by the atmospheric pressure seal is lower than atmosphere.

A developer container includes a frame having a developer storage chamber which stores a conveying member, a developing chamber in which a developer bearing member and a supplying member are arranged, a partition partitioning the developer storage chamber and the developing chamber and provided with a first opening, and a second opening which connects an interior of the developing chamber and an exterior of the frame. A filter allows passage of air and restricts passage of the developer, with the filter being fixed to the frame so as to cover the second opening. The conveying member is deformable such that the developer is conveyed from the developer storage chamber to the developing chamber via the first opening by deformation of the conveying member being released, and the conveying member conveys the developer such that the developer passes above the supplying member.

A developing device includes a developer roller to rotate in a rotation direction, a photosensitive body adjacent the developer roller, and an air flow passage extending through a non-image forming region at a longitudinal end of the developer roller. A closest position is defined where the developer roller and a photosensitive body are closest to one another. The air flow passage extends from inside the developing device and forms an air flow directed toward an upstream side of the closest position, relative to the rotation direction of the developer roller.

A developing device includes a developing container having a first stirring chamber and a second stirring chamber that are arranged in juxtaposition with each other and a developer carrier that carries toner in the second stirring chamber. The developing container includes a duct, an air suction port, a first filter, and a second filter. The duct is arranged adjacently to the second stirring chamber and allows air in the second stirring chamber to flow out to an exterior. The air suction port is open along a longitudinal direction of the second stirring chamber and allows communication between inside the second stirring chamber and inside the duct. The first filter covers the air suction port. The second filter is arranged on a downstream side of the first filter in an air circulation direction in the duct and covers an air circulation path in the duct.