A developing device includes a developing container and a second stirring member. The developing container includes a second feeding chamber and a developer discharge outlet disposed on the downstream side end of the second feeding chamber. The second stirring member includes a second feeding blade, a restricting part for conveying developer in the opposite direction to the second feeding blade, and a discharging blade for conveying the developer in the same direction as the second feeding blade so as to discharge the developer from the developer discharge outlet. The second rotation shaft includes a large shaft diameter part provided with the second feeding blade, a small shaft diameter part provided with the restricting part and the discharging blade, and a shaft diameter changing part positioned at a boundary between the large shaft diameter part and the small shaft diameter part.

A development device includes a development container and a second agitation member. The development container includes a second transport chamber and a developer discharge port which is provided at the end portion of the second transport chamber on a downstream side. The second agitation member includes a second transport blade, a damming member which dams a developer, a regulation portion which transports the developer in a direction opposite to the second transport blade and a discharge blade which discharges the developer from the developer discharge portion. A second rotation shaft includes a large shaft diameter portion on which the second transport blade is provided, a small shaft diameter portion on which the regulation portion and the discharge blade are provided and a shaft diameter change portion. The damming member is arranged between the shaft diameter change portion and the end portion of the second transport blade on the downstream side.

A developing device includes a first transport member and a second transport member that are respectively disposed in a first transport path and a second transport path arranged in a vertical direction and that transport developer so as to circulate the developer between the first transport path and the second transport path; a developing member that is disposed to face the first transport path and that receives the developer from the first transport path; and a third transport member that is disposed in a third transport path through which the developer that has not been used by the developing member is collected and transported to the second transport path. A central shaft of the second transport member is disposed farther in a vertically upward direction than is a central shaft of the third transport member.

A developing device includes a first transport member and a second transport member that are respectively disposed in a first transport path and a second transport path arranged in a vertical direction and that transport developer so as to circulate the developer between the first transport path and the second transport path; a developing member that is disposed to face the first transport path and that receives the developer from the first transport path; and a driving device that operates such that a relative speed ratio between a rotational speed of the developing member and a rotational speed of the second transport member is changeable.

A developing device includes a first transport member and a second transport member that are respectively disposed in a first transport path and a second transport path arranged in a vertical direction and that transport developer so as to circulate the developer between the first transport path and the second transport path; a developing device body in which the first transport path and the second transport path are formed; and a developer discharging structure that discharges excess developer discharged from the first transport path to outside through the second transport path or through a space between an end portion of the second transport path and the developing device body.

A developing device includes: a case in which a hollow transporting path is formed; a transporting member configured to transport a developer in the transporting path; a support portion fixed to an end portion of the case by a fastening member to support the transporting member at an end portion of the transporting path; and a cooling unit fixed by being sandwiched between the support portion and the case.

A developing device includes a first transport member and a second transport member that are respectively disposed in a first transport path and a second transport path arranged in a vertical direction and that transport developer so as to circulate the developer between the first transport path and the second transport path. The developing device includes a developing device body in which the first transport path and the second transport path are formed. The developing device also includes a developer discharging structure that discharges excess developer discharged from the first transport path to outside through the second transport path or through a space between an end portion of the second transport path and the developing device body.

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 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.