A developing device includes a developer bearer and a stirring conveyor. The stirring conveyor includes a first conveying chamber including a conveying member and a second conveying chamber to receive the developer from an end of the first conveying chamber. The conveying member includes a forward winding blade, a reverse winding blade, and a shaft portion on which the forward winding blade and the reverse winding blade are mounted with a space therebetween. A circumferential phase of the conveying member at a start position of the reverse winding blade is different from a circumferential phase of the conveying member at an end position of the forward winding blade. The conveying member is disposed in the first conveying chamber so that the space is opposite a portion at which the second conveying chamber receives the developer from the end of the first conveying chamber.

An imaging system includes a developing chamber, a first conveyance path, a second conveyance path, a first air passage and a second air passage. A developing roller located in the developing chamber carries a developer to a developing region where the developing roller is closest to an image carrier. A first stirring-conveying portion is located in the first conveyance path adjacent the developing roller to supply the developer to the developing roller. A second stirring-conveying portion is located in the second conveyance path adjacent the first conveyance path to circulate the developer between the second conveyance path and the first conveyance path. The first air passage has an inlet coupled to the developing chamber and an outlet coupled to the second conveyance path, and the second air passage has an inlet coupled to the second conveyance path and an outlet coupled to the developing chamber.

Provided is a developing device having a first transport member and a second transport member that are disposed in a first transport path and a second transport path provided at an upper side and a lower side in a gravitational direction. The transport members transport a developer so as to cause the developer to circulate between the first transport path and the second transport path. A partition wall that separates the first transport path and the second transport path from each other and has an opening including an open-close member that opens and closes the opening.

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.

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 container, a developer carrier, and a stirring/conveying member. The developer container stores developer containing toner. The developer carrier carries on its surface the toner in the developer container. The stirring/conveying member includes a rotary shaft rotatably supported on the developer container and a stirring blade formed around the outer circumferential face of the rotary shaft and stirs and conveys the developer in the developer container. The stirring/conveying member to be used can be selected from a plurality of types of stirring/conveying members with rotary shafts with different shaft diameters.

A developing device includes a developer container, a developer carrier, and a stirring/conveying member. The developer container stores developer containing toner. The developer carrier carries on its surface the toner in the developer container. The stirring/conveying member includes a rotary shaft rotatably supported on the developer container and a stirring blade formed around the outer circumferential face of the rotary shaft and stirs and conveys the developer in the developer container. The stirring/conveying member to be used can be selected from a plurality of types of stirring/conveying members with rotary shafts with different shaft diameters.

A developing device includes a developer bearer and a stirring conveyor. The stirring conveyor includes a first conveying chamber including a conveying member and a second conveying chamber to receive the developer from an end of the first conveying chamber. The conveying member includes a forward winding blade, a reverse winding blade, and a shaft portion on which the forward winding blade and the reverse winding blade are mounted with a space therebetween. A circumferential phase of the conveying member at a start position of the reverse winding blade is different from a circumferential phase of the conveying member at an end position of the forward winding blade. The conveying member is disposed in the first conveying chamber so that the space is opposite a portion at which the second conveying chamber receives the developer from the end of the first conveying chamber.

A developer conveyor includes a shaft; a first blade helically wound around the shaft in a first direction, a second blade disposed away from an end of the first blade with a gap in a longitudinal axial direction of the developer conveyor and helically wound around the shaft in a second direction opposite the first direction, and a third blade helically wound around the shaft in the first direction at least at a position where the gap is formed.

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.