A developer cartridge includes: a casing; and a sub-unit. The casing has a first opening and a developer chamber. The sub-unit is detachably attached to the developer chamber through the first opening. The sub-unit includes: a cap; a developer container; and an agitation member. The cap seals the first opening. The developer container is disposed in the developer chamber and hermetically accommodating developer therein. The agitation member is disposed in the developer chamber. The agitation member has a first end portion and a second end portion. The agitation member is rotatable relative to the casing about an axis. The axis extends between the first end portion and the second end portion in an axial direction.

A cartridge includes a shutter that opens and closes when the cartridge is attached and detached to a developing unit or image forming apparatus. The cartridge includes a casing having a chamber with a first opening at one end portion allowing toner to flow out of the casing. The cartridge includes a cover that covers the first opening, movable with the casing and having a second opening allowing toner to flow out of the cover. The shutter is located at the one end portion and has a protrusion further from the one end portion than the cover. The developing unit supports the protrusion when the cartridge is mounted thereon, and the casing pivots with the cover relative to the developing unit between a first position where the shutter closes the second opening and a second position where a third opening of the shutter overlaps the second opening.

Toner cartridge includes a housing, an agitator, an auger, a first protrusion, and a second protrusion. The housing includes a first toner accommodating portion having and a second toner accommodating portion. The auger is rotatable about a second axis extending in a first direction and is configured to convey toner from a first toner accommodating portion to the second toner accommodating portion. The first protrusion is positioned at a first side of the second toner accommodating portion. The first protrusion extends in the first direction. The second protrusion is positioned at a second side of the second toner accommodating portion and extends in the first direction.

A developer stirring member is supported by a rotation portion in a container that stores developer and is configured to stir the developer. The developer stirring member includes a base portion and a reinforcement portion. The base portion is a film-like member including a first supported portion and an end portion, the first supported portion being supported by the rotation portion, the end portion being a free end to pivot. The reinforcement portion is a film-like member overlapping only a part of the base portion that is on a first supported portion side.

If a user is not familiar with the operation for the developer supply container, the rotating operation for the developer supply container may be insufficient, so that developer supply container does not reach a predetermined operating position, with the result of abnormal developer supply. by increasing a rotation load of a second gear 6 which is in an operable connection with a drive gear member 12 of the developer receiving apparatus 10 by a function of a locking member 7, the developer supply container 1 mounted to the developer receiving apparatus 10 is rotated toward the supply position. After the developer supply container 1 rotates to the supply position, the locking by the locking member 7 is released, by which the rotation load applied to the second gear 6 is reduced, so that drive transmission, thereafter, to the feeding member 4 for developer supply is smooth.

A developer container includes: a case that stores developer and in which a developer outlet for discharging the developer is formed; a conveying spiral that is rotatably disposed in the case and rotates to convey the developer toward the developer outlet in an axial direction of the conveying spiral; a guide wall that is disposed along the conveying spiral and guides the developer in the axial direction of the conveying spiral; and a push member that is attached to the conveying spiral and rotates with the conveying spiral to push the developer into the developer outlet. A cutout is formed at a portion of the guide wall corresponding to the push member to form a guide portion that guides the developer to the developer outlet.

According to an aspect of the invention, a developing device includes a developing container that accommodates a two-component developer, a toner concentration detecting unit that detects a toner concentration of the developer by a detecting unit exposed to an inner wall of the developing container, a transport member that is disposed within the developing container and stirs and transport the developer with a transport blade having a pitch that is equal to or less than a size of the detecting unit of the toner concentration detecting unit, and a plurality of gap holding members that is provided at a position facing the toner concentration detecting unit of the transport member and holds a gap such that a tip thereof is abutted against the inner wall of the developing container.

A toner cartridge includes a toner lock member. A developing unit includes a developing lock member configured to lock a developing shutter in a first closed position in a state where the toner cartridge is detached from the developing unit. When the toner cartridge is detached from the developing unit, the toner lock member is in a lock position. When the toner cartridge is attached to the developing unit, the casing is pivotable relative to the developing unit between a first position and a second position. When the casing is at the first position, the toner shutter closes a toner opening and the developing shutter is at the first closed position. When the casing is at the second position, the toner shutter opens the toner opening, the toner lock member is in an unlock position, and the developing shutter is at the first open position.

A developing apparatus includes a developing container, a lid that is fixed to the developing container and defines a storage space for developer, a developing roller, and a conveyance member for conveying the developer toward the developing roller. The conveyance member includes a sheet and a support member that supports the sheet and is rotatable about a rotation axis together with the sheet. The sheet has a first distance between the rotation axis and an edge of the sheet in a state in which the sheet is unbent. The lid includes a corner portion that extends the storage space outward of an imaginary circle with a radius of the first distance centered on the rotational axis, and a contact portion that protrudes from the corner portion to the inner side of the imaginary circle and is configured to come into contact with the rotating sheet.

A cartridge includes a shutter that opens and closes when the cartridge is attached and detached to a developing unit or image forming apparatus. The cartridge includes a casing having a chamber with a first opening at one end portion allowing toner to flow out of the casing. The cartridge includes a cover that covers the first opening, movable with the casing and having a second opening allowing toner to flow out of the cover. The shutter is located at the one end portion and has a protrusion further from the one end portion than the cover. The developing unit supports the protrusion when the cartridge is mounted thereon, and the casing pivots with the cover relative to the developing unit between a first position where the shutter closes the second opening and a second position where a third opening of the shutter overlaps the second opening.