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 developing device includes: 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 and that transport a developer so as to cause the developer to circulate between the first transport path and the second transport path; an ejecting mechanism that is provided in the first transport path disposed at the upper side in the gravitational direction and that ejects an excess developer; and a reverse helical section that is disposed in front of a support that supports the second transport member disposed at the lower side in the gravitational direction, the reverse helical section helically extending in a reverse direction relative to a helical section provided for circulating the developer, the developer being transported to the ejecting mechanism by the reverse helical section.

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 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.

A developing device includes: 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 and that transport a developer. The developing device also includes an ejecting path that is provided in the first transport path disposed at the upper side in the gravitational direction and that ejects an excess developer. The developing device includes a reverse helical section that is disposed in front of a support that supports the second transport member. The reverse helical section helically extends in a reverse direction relative to a helical section provided for circulating the developer, the developer being transported to the ejecting path by the reverse helical section.

A development device including: a developer bearing; a regulation portion; a magnetic field generation member that is provided inside of the developer bearing member, the magnetic field generation member having: a development pole; a first magnetic pole; and a second magnetic pole; wherein the magnetic field generation member has a region satisfying |(Br(θa)−Br(θc))/10|<0.3, wherein Br(θa) is a magnetic flux density in a normal direction relative to the surface of the developer bearing member on a position shifted by −5° from a point nearest to the regulation portion on the developer bearing member around a center of the developer bearing member, and Br(θc) is the magnetic flux density around the developer bearing member on a position shifted by +5° from the point nearest to the regulation portion on the developer bearing member.

A developing device includes a developer carrying member for carrying and feeding a developer, first and second chambers for circulating the developer, and a partition wall. A first feeding member feeds the developer in the first chamber in a first feeding direction, and a second feeding member feeds the developer in the second chamber. The second feeding member includes a shaft, a first helical portion for feeding the developer in a second feeding direction, and a second helical portion for feeding the developer in the first feeding direction. The second helical portion is provided on the shaft and provided downstream of the first helical portion via a region where no helical portion is provided. A rib is provided on a first inner surface of the second chamber, with the rib disposed opposite the region where no helical portion is provided and extending upwardly in a vertical direction.

A developing device includes a developer bearer, a casing defining an upper compartment to contain the developer and a lower compartment disposed lower than the upper compartment, to contain the developer, and a first conveyor and a second conveyor disposed in the upper compartment and the lower compartment, respectively, to convey the developer in a longitudinal direction of the developer bearer and circulate the developer between the upper compartment and the lower compartment through a first communicating opening, through which the developer is conveyed upward, and a second communicating opening. A developer-lifting range of the upper compartment, which opposes the first communicating opening, is larger in volume than a developer-lifting range of the lower compartment. One of the upper compartment and the lower compartment is disposed adjacent to the developer bearer to supply the developer to the developer bearer.

A developer cartridge includes: a casing; and a sub-unit. The casing has a first opening and a developer chamber. The sub-unit is detachably attached to the developer chamber through the first opening. The sub-unit includes: a cap; a developer container; and an agitation member. The cap seals the first opening. The developer container is disposed in the developer chamber and hermetically accommodating developer therein. The agitation member is disposed in the developer chamber. The agitation member has a first end portion and a second end portion. The agitation member is rotatable relative to the casing about an axis. The axis extends between the first end portion and the second end portion in an axial direction.

A developer container includes: a case that stores developer and in which a developer outlet for discharging the developer is formed; a conveying spiral that is rotatably disposed in the case and rotates to convey the developer toward the developer outlet in an axial direction of the conveying spiral; a guide wall that is disposed along the conveying spiral and guides the developer in the axial direction of the conveying spiral; and a push member that is attached to the conveying spiral and rotates with the conveying spiral to push the developer into the developer outlet. A cutout is formed at a portion of the guide wall corresponding to the push member to form a guide portion that guides the developer to the developer outlet.