A toner conveying device includes a drop conveyance passage, an inclined conveyance passage, a conveyor, and a flexible sheet. Toner drops by its own weight through the drop conveyance passage. The inclined conveyance passage communicates with a lower end of the drop conveyance passage and extends obliquely downward. The conveyor has a coil shape or screw shape, is disposed in the inclined conveyance passage, and rotates in a specified direction to convey the toner obliquely downward. The flexible sheet is disposed in the drop conveyance passage, has a leading end to contact the conveyor, and swings in conjunction with rotation of the conveyor.

A transport device includes a transport path that includes an opening through which a developer flows into the transport path, an opening and closing portion that is provided to be movable along the transport path and that opens and closes the opening, and a transport body that is disposed in the transport path, that includes a blade formed in a spiral shape on an outer periphery of a shaft portion, that transports the developer flowing into the transport path through the opening and moves the opening and closing portion to an opening position with the blade by rotating forward, and that idly rotates with respect to the opening and closing portion moved to the opening position in a case of forward rotation.

A developing device includes a developer container including first and second chambers, first and second communication portions to permit the developer to communicate with the first and second chambers, first and second screws provided in the first and second chambers, respectively, and a developer discharging portion. The developer discharging portion is provided in a passage continuous with the first chamber and downstream of the first communication portion. In the developing device, a discharging method includes a step for inserting a shielding member into the second communication portion via an inserting opening of the developer container, and a step for discharging the developer from the developing device via the developer discharging portion, by rotating the first and second screws in a same direction as a direction of rotating during a developing operation in a state where the shielding member is inserted into the second communication portion.

A developing device includes a developer carrier to carry a developer, and a developer conveyor to supply the developer to the developer carrier. The developer conveyor includes a shaft extending in an axial direction to rotate in a rotational direction, a helical blade having a conveying surface to convey the developer around the shaft along the axial direction, and a protrusion attached to a rear surface of the helical blade, which faces the conveying surface, and having a leading surface extending from an upstream end to a downstream end in the rotational direction of the shaft.

A powder conveying device includes an inflow portion, a discharge portion, and a conveying screw. Powder flows into the inflow portion from outside of the powder conveying device. The powder flows out from the discharge portion to the outside of the powder conveying device. The conveying screw includes a shaft and conveys the powder from the inflow portion to the discharge portion in a conveying direction. A surface portion of the shaft at at least one of an upstream end or a downstream end of the shaft in the conveying direction, in at least one of the inflow portion or the discharge portion has a lower friction with the powder than another surface portion of the shaft at a position other than the at least one of the upstream end or the downstream end.

A developing device includes a developer container including first and second chambers between which the developer is circulated, first and communication portions to permit the developer to communicate with the first and second chambers, first and second screws provided in the first and second chambers, respectively, and a developer discharging portion. The developer discharging portion is provided in a passage continuous with the first chamber of a downstream of the first communication portion. In the developing device, a discharging method includes a step for inserting a shield member into the second communication portion via an inserting opening of the developer container, and a step for discharging the developer from the developing device via the developer discharging portion, by rotating the first and second screws in a direction same as a direction of rotating during a developing operation in a state where the shielding member is inserted into the second communication portion in the inserting step.

An image forming system includes a developer carrier and a developer conveyor that supplies a developer to the developer carrier. The developer conveyor includes a shaft extending in an axial direction, a helical blade and a protrusion around the shaft.

A developing device includes a developer bearer, a developer regulator, a developer supply passage, and a stopper. The developer bearer includes a magnetic field generator and is configured to bear a developer containing toner and magnetic carriers and conveys the developer to a developing area by rotation. A stopper prevents the developer blocked by the developer regulator from moving to a surface of the developer bearer, while securing a supply path for passing the developer in the developer supply passage to the developer bearer between the stopper and an upper end of a side wall of the developer supply passage that is opposite to the developing bearer. A width of the supply path in a direction perpendicular to a direction of a rotation axis of the developer bearer is in a range of 7%-10% of a circumference of an outer diameter of the developing bearer.

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 cartridge including a housing to contain a developer and including a developer outlet from which the developer is dischargeable. A transport member is arranged inside the housing to rotate to transport the developer to the developer outlet. A volume adjustment member is insertable inside the transport member opposite to the developer outlet to adjust an inside volume of the housing.