A stirring/conveying member has a rotary shaft rotatably supported in a powder container, a first helical blade formed on the circumferential surface of the rotary shaft and conveying powder in the axial direction by the rotation of the rotary shaft, and a second helical blade formed on the circumferential surface of the rotary shaft to overlap the forming region of the first helical blade, spiraling in the opposite phase to the first helical blade, and having a smaller radial height than the first helical blade. The first helical blade crosses the second helical blade at least at one place in one turn about the rotary shaft. At least one of the radial heights of the first and second helical blades equals zero at the intersection of the first and second helical blades.

An image forming apparatus includes an image forming portion having a first feeding member to feed developer in a first chamber, a second feeding member to feed the developer in a second chamber; and a control portion to execute a plurality of modes by suspending image forming. A first mode circulates the developer in a condition in which a ratio of a rotational speed of the developer bearing member to a rotational speed of the first and second feeding members is decreased as compared to that in forming the images; and a second mode increases the ratio of the rotational speed of the developer bearing member to the rotational speed of the first feeding member as compared to that in forming the images. The second mode is executed after the first mode and before resuming the image forming operation.

A developing cartridge includes: a casing, a developing roller, a first agitator, a supply roller, and a second agitator. The casing is configured to accommodate toner. The developing roller is rotatable about a developing roller rotation axis extending in a first direction. The first agitator is configured to agitate the toner. The first agitator is rotatable about a first agitator rotation axis extending in the first direction. The supply roller is positioned between the first agitator and the developing roller. The supply roller is rotatable about a supply roller rotation axis extending in the first direction. The second agitator is positioned between the supply roller and the first agitator. The second agitator is rotatable about a second agitator rotation axis extending in the first direction. A rotation locus of the second agitator is positioned outside of a rotation locus of the first agitator.

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 developer bearer, a first conveying screw conveying developer from one end to another end of a first conveyance path in a first direction, a second conveying screw conveying the developer in a direction opposite to the first direction in a second conveyance path, and a partition having a first communication port communicating the one end of the first conveyance path and the second conveyance path. A shaft diameter of the first conveying screw from one end to a position away from the first communication port by a first predetermined distance is smaller than a shaft diameter of another portion of the first conveying screw. A shaft diameter of the second conveying screw from one end to a position away from the first communication port by a second predetermined distance is larger than a shaft diameter of another portion of the second conveying screw.

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.

A developing device includes: a developer carrying member; a developer container including a developer accommodating portion, a developing opening and a developing chamber; and a developer supplying member including a shaft member and a feeding member. The feeding member includes a first feeding portion having a length L1 and a radius R1, and includes a second feeding portion having a length L2 and a radius R2. When a length of the developing opening is L3, a shortest length from the developing opening to the rotation center of the shaft member is L4, and a length from the developer carrying member to the rotation center of the shaft member is L5, the following relationships are satisfied:

L1<L3<L2, and

L4<R1<L5.

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.

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 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.