A developing cartridge may include: a casing; a developing roller extending in a first direction; a developing-roller gear; a coupling including a coupling gear; a first idle gear; a second idle gear; an agitator; a first agitator gear; and a protrusion. The developing-roller gear, the coupling, the first idle gear, the second idle gear, the first agitator gear, and the protrusion may be positioned at an outer surface of the casing. The protrusion may be positioned between a first axis of the coupling and a third axis of the first agitator gear in a second direction connecting the first and third axes. The protrusion may be positioned outside an addendum circle of the developing-roller gear, an addendum circle of the coupling gear, an addendum circle of the first idle gear, and an addendum circle of the second idle gear. The first agitator gear may be spaced apart from the protrusion in the first direction.

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.

An imaging system comprises a stirring-conveyance member to supply developer to a developing roller. The stirring-conveyance member includes a spiral structure to convey the developer and a reverse spiral structure disposed downstream the spiral structure in a conveying direction of the developer. The reverse spiral structure has a maximum outer diameter at an upstream end in the conveying direction and a minimum outer diameter at a downstream end in the conveying direction. The minimum outer diameter is approximately ⅗ or less, of the maximum outer diameter.

A first development chamber accommodates an agitator. A second development chamber accommodates a development roller and a supply roller. The second development chamber is located above the first development chamber. A toner cartridge contains toner to be supplied to the first development chamber. A transfer device is located above a photosensitive drum in a state where a drum unit is attached to a main housing. The transfer device transfers toner on the photosensitive drum to a sheet. An agitator includes a shaft and a blade. The shaft is rotatably supported by a development housing. The blade is rotatable together with the shaft. The blade has a first end fixed to the shaft and a second end located away from the first end. The agitator is configured such that, when rotated, the second end of the blade reaches a height of an opening in the development housing in a vertical direction.

A developing apparatus includes a replenishment conveyance screw portion to convey replenishment developer from a developer replenishment portion toward a first communication portion. First, second and third blade portions are formed in a spiral shape on an outer circumferential surface of a rotation shaft of the replenishment conveyance screw portion. A pitch of the first blade portion, a pitch of the second blade portion, and a pitch of the third blade portion are each larger than a pitch of a blade of a second conveyance screw portion, and the third blade portion is continuously formed in a region between a terminal end of the first blade portion and a starting end of the second blade portion.

An image forming apparatus includes a development device, a toner storage part, a drive unit, a control unit, and an image carrying member. The development device includes a development casing, a developer carrying member, a first stirring transport member, a second stirring transport member, a discharge impeller, and a reverse transport impeller. The development casing includes a first partition wall, a communication part, a developer replenishment port, and a developer discharge part. The first stirring transport member includes a first rotation shaft and a first transport impeller. The second stirring transport member includes a second rotation shaft and a second transport impeller. The control unit can perform a developer discharge mode, in which the first rotation shaft and the second rotation shaft are rotated reversely during a non image formation period, so that the developer around the reverse transport impeller is discharged through the developer discharge part.

A particle conveying device includes a storage portion that stores pressure sensitive adhesive particles that contain at least a binder resin, have a pressure-induced phase transition property, and have a sulfur content in a range of 0.1 mass % or more and 0.5 mass % or less relative to the entire pressure sensitive adhesive particles as measured by X-ray fluorescence; and a conveying member that is disposed in the storage portion and rotates about a shaft that extends in one direction inside the storage portion to thereby convey the pressure sensitive adhesive particles in a direction along the shaft inside the storage portion.

A developer storage container includes a storage portion, a communication portion, a scooping portion, and a guide portion. The storage portion conveys developer stored therein in a conveying direction along a rotation axis by being rotated around the rotation axis in a specific direction. The communication portion connects the storage portion to an opening portion facing the conveying direction. The scooping portion includes a scooping surface facing the specific direction at an end of the storage portion on a downstream side in the conveying direction and radially outside the communication portion to scoop up the developer in contact with the scooping surface as the storage portion rotates in the specific direction. The guide portion lies radially inside the scooping portion to be contiguous with the scooping surface and an inner peripheral surface of the communication portion, and guides the developer scooped up by the scooping portion to the communication portion.

An image forming apparatus includes a developer bearing member, a frame having a storage member, and a first temperature detection unit. The storage member is for storing a developer for the developer bearing member to record an image on a recording material. The storage member includes an attachment part in which a supply container enclosing a developer is removably attachable to the attachment part. With reference to a recording material conveyance path having a center in a width direction of the recording material that is orthogonal to a recording material conveyance direction and in a case where an area on one side of the conveyance path center is a first area and the area on the other side of the conveyance path center is a second area, the attachment part is arranged in the first area and the first temperature detection unit is arranged in the second area.

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.