An opposing surface of a partition opposing a first conveyance screw includes an arc-shaped guide portion for guiding conveyance of developer at least on an upstream side in a first conveyance direction of the first conveyance screw. The guide portion is extended from a bottom portion of a first chamber opposing the first conveyance screw and formed along an outer periphery of the first conveyance screw. As seen in a cross section orthogonal to a rotation axis of the first conveyance screw, the opposing surface of the partition within a predetermined area includes the guide portion over an angle of 30% or more of the predetermined area in a direction of rotation of the first conveyance screw.

A developing device includes a developer carrying member for carrying a developer; a circulation path along which the developer is circulated; a carrier supplying portion; a discharge opening, provided in the circulation path, through which a portion of the developer is to be overflowed and discharged; and a feeding member comprising a rotation shaft and a blade portion including a helical portion. An outer diameter of the blade portion formed in a first region including at least a portion opposing the discharge opening is smaller than that in a second region adjacent to the first region with respect to a rotation shaft direction. A smaller average angle formed between the rotation shaft and a developer feeding surface of the blade portion in the first region is smaller than that in the second region.

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 powder transporting device includes a first agitating and transporting section that agitates and transports powder, a receiving section that receives the powder from the first agitating and transporting section, a second agitating and transporting section that is arranged below the first agitating and transporting section in a vertical direction and agitates and transports the powder, an upward transport section that is arranged on a downstream side in a transport direction of the second agitating and transporting section and transports the powder transported from the second agitating and transporting section to the first agitating and transporting section above, and a speed increasing section that increases a rotation of a rotating shaft of any one of the first agitating and transporting section, the second agitating and transporting section, or the receiving section and transmits the rotation to the upward transport section.

A developing apparatus including: a first chamber including a first conveyance member conveying developer in a first direction; a second chamber including a second conveyance member having a conveyance portion conveying the developer in a second direction opposite to the first direction and a return conveyance portion provided downstream of the conveyance portion in the second direction to convey the developer in the first direction; a first partition wall provided between the first chamber and the second chamber to form a first communication portion and a second communication portion to form a circulation route; and a bearing member configured to rotatably support the second conveyance member and including: a discharge port provided downstream of the return conveyance portion; and a second partition wall extending from the bearing member in the first direction to cover a portion of the return conveyance portion confronting the first communication portion.

A developing device includes a developing container, a detecting unit including a base portion and a detecting portion, a feeding path, a feeding screw, and a recessed portion provided on a side wall of the developing container. The recessed portion is disposed so as to project toward the feeding screw in the feeding path. The side wall includes a projected region projected toward the screw portion in the feeding path by the recessed portion and a region other than the projected region. The feeding screw includes a first screw portion opposing the projected region and a second screw portion opposing the region other than the projected region. The first screw portion includes a rotation shaft which includes a portion having a shaft diameter smaller than a shaft diameter of a rotation shaft of the second screw portion.

A developing device includes a developer container to contain developer including toner and magnetic carrier, the developer container; a developer bearer to carry, by rotation, the developer to a developing range facing a latent image bearer; a communication opening in a wall defining the developer container; a toner conveyance passage connected to the communication opening; and a cylindrical magnet having a magnetic pole arrangement parallel to an axis of the cylindrical magnet. The cylindrical magnet is disposed to enclose a space overlapping with the communication opening on a cross section perpendicular to the axis of the cylindrical magnet.

A toner conveying device includes a case that can store therein toner to be conveyed, a conveyance member rotatably supported at both ends thereof by the case and configured to rotate to convey the toner inside the case in a conveying direction set in advance, and a pushing member pushed against the conveyance member and configured to slide on an outer peripheral portion of the conveyance member as the conveyance member rotates. The pushing member includes a first sheet member having flexibility and abutting on the outer peripheral portion in a first direction intersecting with a rotational axis direction of the conveyance member to push the conveyance member and a second sheet member having flexibility and abutting on the outer peripheral portion in a second direction, which is different from the first direction, intersecting with the rotational axis direction to push the conveyance member.

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 rotatable developing member, a developing container, a first communication opening, a second communication opening, a first feeding screw including a first rotation shaft, first and second blade portions, a second feeding screw including a second rotation shaft, third and fourth blade portions, a developer discharge opening provided upstream of an upstream end of the second communication opening in a first direction, and a third communication opening provided upstream of the upstream end of the second communication opening in the first direction. In a second direction opposite to the first direction, the third communication opening overlaps with the second blade portion. In the first direction, the third communication opening overlaps with the fourth blade portion. In the first direction, a downstream end of the third communication opening is positioned downstream of a downstream end of the developer discharge opening.