A developing apparatus includes a developing container to accommodate a developer and having first and second chambers divided by a partition wall for supplying the developer to a rotatable developing member and first and second communicating portions to allow the developer to move between first and second chambers by conveyance screws. A third communicating portion is disposed between the first and second communicating portions and above the conveyance screws to allow air inside the developing container to move between the first chamber and the second chamber. The developing container further includes a third chamber disposed above the second chamber in the vertical direction and accommodates initial developer in an unused state of the developing apparatus, and an opening portion for discharging the air inside the developing container to outside of the developing container is provided in the third chamber, with the opening being disposed above the third chamber.

A feeding screw includes a rotation shaft, and a plurality of blades helically formed with threads on the rotation shaft. The feeding screw includes a section in which a helix angle of each of the blades is not more than 56.5.

A feeding screw for feeding a developer includes a rotation shaft, and a helical blade provided on the rotation shaft and including a plurality of threads. The feeding screw includes a first blade helically formed with a single thread on the rotation shaft, a second blade helically formed with a single thread on the rotation shaft, and a third blade helically formed with a single thread on the rotation shaft. With respect to a direction along the rotation shaft, a gap is provided between a downstream end portion of the second blade and an upstream end portion of the first blade. The gap is disposed corresponding to a region where the first blade is continuously formed.

A developing device of the present disclosure includes a developing container, a first stirring-conveyance member, a second stirring-conveyance member, and a developer carrier. The developing container includes a first conveyance chamber, and a second conveyance chamber arranged above the first conveyance chamber. The first stirring-conveyance member conveys a developer in the first conveyance chamber in a first direction, while stirring the developer. The second stirring-conveyance member conveys the developer in the second conveyance chamber in a second direction, while stirring the developer. The first stirring-conveyance member includes a plurality of spiral blades formed on an outer peripheral surface of a rotary shaft, and a reverse spiral blade which is arranged downstream of the spiral blades in the first direction and opposite in winding direction to the spiral blades. Downstream ends of the spiral blades in the first direction are located substantially equally distant from the reverse spiral blade.

A developing device of the present disclosure includes a developing container, a first stirring-conveyance member, a second stirring-conveyance member, and a developer carrier. The developing container includes a first conveyance chamber, and a second conveyance chamber arranged above the first conveyance chamber. The first stirring-conveyance member conveys a developer in the first conveyance chamber in a first direction, while stirring the developer. The second stirring-conveyance member conveys the developer in the second conveyance chamber in a second direction, while stirring the developer. The first stirring-conveyance member includes a plurality of spiral blades formed on an outer peripheral surface of a rotary shaft, and a reverse spiral blade which is arranged downstream of the spiral blades in the first direction and opposite in winding direction to the spiral blades. Downstream ends of the spiral blades in the first direction are located substantially equally distant from the reverse spiral blade.

A developing apparatus for an image forming apparatus comprises: a developing roller; a developing housing which rotatably supports the developing roller and receives a two-component developer; a first mixing member installed in the developing housing to mix the developer; and a second mixing member installed in the developing housing to be parallel to the first mixing member and adjacent to the developing roller, wherein the second mixing member comprises: a shaft; a spiral wing part formed along the shaft; and a plurality of ribs formed so as to protrude from the surface of the shaft.

A developing device includes a developing container, first and second stirring-conveyance members, a developer carrier, a toner concentration sensor, a scraper, and a scraper attachment unit. The second stirring-conveyance member includes a rotation shaft, a first spiral blade to convey developer in an axial direction, and a second spiral blade to overlap a region where the first spiral blade is formed, which is opposite to the first spiral blade in phase, and lower than the first spiral blade in height in a radial direction. An absent region, where the second spiral blade does not exist, is formed in one pitch of the first spiral blade, the one pitch facing the toner concentration sensor. The scraper attachment unit is formed to extend, along a straight line passing through intersection points of the first and second spiral blades and parallel to the rotation shaft, into the absent region.

An image forming apparatus includes an image forming portion configured to form an image on a recording media and including a developer bearing member configured to bear developer and carry the developer, a regulating portion disposed opposite to the developer bearing member and configured to regulate an amount of the developer on the developer bearing member, a first chamber configured to supply the developer to the developer bearing member, and a second chamber configured to communicate with the first chamber to form a circulating route of the developer. In addition, a first feeding member feeds the developer in the first chamber, and a second feeding member feeds the developer in the second chamber. A control portion executes, in a non-image forming state, a mode of driving the developer bearing member in a condition in which the first feeding member is stopped.

A developing unit configured for operating with a two-component developer material includes carrier particles to which the toner particles are adhered. The developing unit includes: at least one developer member rotatably mounted in the housing and configured for transferring toner particles to a photoconductor member, and a conveying assembly configured for conveying toner particles to the at least one developer member or away from the at least one developer member. The conveying assembly includes an auger and which includes a bar shaped shaft, a helical screw blade arranged around the shaft, and at least a first elongate element arranged at a distance of the shaft.

A developer cartridge assembled to a developing device defining therein a developing chamber. The developer cartridge includes a first accommodating portion, and a first agitator. The first accommodating portion accommodates therein a developing agent and is positioned beside the developing device. The first accommodating portion includes a first wall part neighboring the developing device. The first wall part is formed with a first through-hole and a second through-hole. The first through-hole is open diagonally downward from the first accommodating portion to the developing device. The second through-hole is open diagonally upward from the first accommodating portion to the developing device. The first through-hole and the second through-hole allow communication between an interior of the first accommodating portion and the developing chamber. The first agitator is rotatably disposed in the first accommodating portion and in sliding contact with the first wall part in a vertical direction.