A developing device includes a developer tank holding a developer, and a transporting member stirring and transporting the developer. The transporting member includes first and second screws each provided with a rotary shaft having a spiral blade disposed on an outer circumferential face of the rotary shaft. The first and second screws are disposed such that the rotary shafts are parallel to each other. The developer tank includes a first compartment accommodating the first screw, a second compartment accommodating the second screw, a partition separating the first compartment and the second compartment, and a circulation zone. The circulation zone includes an opening in the partition that allows the developer to flow through. The first and second compartments have bottom faces at different heights. A protrusion is formed on a bottom face in the circulation zone.

A developing device comprising a developer transporting unit including a developer inlet through which a developer is reintroduced, a developer outlet through which the developer is discharged, and a developing roller mounted in the developer transporting unit; and a developer circulator including a first connection opening connected to the developer outlet, to receive the developer discharged through the developer outlet, a second connection opening connected to the developer inlet to reintroduce the developer through the developer inlet into the developer transporting unit, a waste opening through which the developer is discarded, and a guide member mounted in the developer circulator to selectively guide the developer received through the first connection opening to the second connection opening or to the waste opening.

A transporting member includes a rotating shaft and plural helical blades that helically extend around the rotating shaft and that transport a transport object in a direction of the rotating shaft as the rotating shaft rotates, each helical blade including a downstream side surface at a downstream side in a transporting direction and an upstream side surface at a side opposite to the downstream side surface. A portion of at least one of the helical blades has a gap that enables the transport object to move in the direction of the rotating shaft, and the at least one of the helical blades includes an upstream section that extends upstream in a rotating-shaft rotation direction, in which the rotating shaft rotates, from the gap. The upstream section includes a portion in which an inclination angle of the downstream side surface is less than an inclination angle of the upstream side surface.

A toner cartridge includes a first casing, a second casing, an auger screw, and a shutter. The first casing has a first internal space. The second casing has: a second internal space smaller than the first internal space; a first opening allowing toner in the second internal space to be discharged; and a second opening allowing air in the second internal space to be sent to an outside. The auger screw is rotatable about a first rotation axis and configured to convey toner in the first internal space to the second internal space. The shutter is rotatable relative to the second casing about a second rotation axis between a first position in which the shutter closes the first opening and a second position in which the shutter opens the first opening. In a state where the shutter is at the second position, the shutter does not close 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.

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 toner cartridge includes a first casing, a second casing, an auger screw, and a shutter. The first casing has a first internal space. The second casing has: a second internal space smaller than the first internal space; a first opening allowing toner in the second internal space to be discharged; and a second opening allowing air in the second internal space to be sent to an outside. The auger screw is rotatable about a first rotation axis and configured to convey toner in the first internal space to the second internal space. The shutter is rotatable relative to the second casing about a second rotation axis between a first position in which the shutter closes the first opening and a second position in which the shutter opens the first opening. In a state where the shutter is at the second position, the shutter does not close the second opening.

A developing device comprising a developer transporting unit including a developer inlet through which a developer is reintroduced, a developer outlet through which the developer is discharged, and a developing roller mounted in the developer transporting unit; and a developer circulator including a first connection opening connected to the developer outlet, to receive the developer discharged through the developer outlet, a second connection opening connected to the developer inlet to reintroduce the developer through the developer inlet into the developer transporting unit, a waste opening through which the developer is discarded, and a guide member mounted in the developer circulator to selectively guide the developer received through the first connection opening to the second connection opening or to the waste opening.

A powder container includes a collection port to receive and collect powder from outside; a driven unit that is disposed on one end side in a width direction of the powder container and to which drive is transmitted from outside; a first rotary shaft that rotates by the drive transmitted to the driven unit; a first gear disposed on other end side of the powder container and rotating with the first rotary shaft; a second rotary shaft that is disposed on the other end side, that includes a second gear to which drive is transmitted from the first gear, and that rotates with the second gear; and a driving gear that is disposed on the second rotary shaft in a position between the second gear and a central portion in the width direction of the powder container, and that rotates with the second rotary shaft to transmit drive to outside.

The developing device includes a developer bearer, a conveyor, a casing including a ceiling, and a seal. The developer bearer is configured to bear a developer and develop a latent image. The conveyor is configured to convey and stir the developer. The casing is configured to contain the developer, the developer bearer, and the conveyor. The seal is configured to seal the inside of the casing to form a closed space that encloses the developer in the developing device. The conveyor is configured to be partially or entirely buried in the developer enclosed in the closed space in both of a normal posture and an upside-down posture of the developing device. A cross-sectional area of the closed space in a horizontal plane gradually increases from a top of the ceiling of the casing toward a bottom of the developing device in the normal posture of the developing device.