The developing device includes a development container, a developer carrier, and a restricting blade. The development container has an opening. The developer carrier has a development area. The development container includes a pair of side frames, and a pair of side wall portions. In each of the pair of side wall portions, a seal member insertion hole extending through in the rotation-axial direction is formed at a position facing an end edge of the restricting blade in the rotation-axial direction. The developing device includes a blade-side side seal inserted in the seal member insertion hole to block a gap between the restricting blade and the side wall portion.

An imaging system includes a developing chamber, a first conveyance path, a second conveyance path, a first air passage and a second air passage. A developing roller located in the developing chamber carries a developer to a developing region where the developing roller is closest to an image carrier. A first stirring-conveying portion is located in the first conveyance path adjacent the developing roller to supply the developer to the developing roller. A second stirring-conveying portion is located in the second conveyance path adjacent the first conveyance path to circulate the developer between the second conveyance path and the first conveyance path. The first air passage has an inlet coupled to the developing chamber and an outlet coupled to the second conveyance path, and the second air passage has an inlet coupled to the second conveyance path and an outlet coupled to the developing chamber.

In a toner supply device (40), a horizontal transport portion (42) is connected to a vertical transport portion (41). A stirring transport screw (25) includes a rotary shaft (25a) and a supply blade (25c), and transports toner in the horizontal transport portion (42) toward the rotary shaft (25a). A drive input gear (50) inputs a rotational drive force to the rotary shaft (25a). A crank shaft (47) has a central shaft (47a) connected to the drive input gear (50) and is rotated at a lower speed than the rotary shaft (25a), and an eccentric shaft (47c) extending in parallel to the central shaft (47a) from a position radially outward from the central shaft. One end of the toner loosening member (45) is connected to the eccentric shaft (47c), and the toner loosening member (45) is reciprocatingly moved in the vertical direction in the vertical transport portion (41) due to a circumferential movement operation of the eccentric shaft (47c) centered on the central shaft (47a).

A developing unit includes a conveying member which rotates to convey the developer to the developer bearing member. The conveying member includes a sheet portion with one end fixed to a rotation shaft and a free end which enters the developing chamber through an opening when the conveying member rotates around a rotation center, wherein relations C>A and B>A are satisfied, where A is a distance from the rotation center to an upstream end of the opening in a rotational direction, B is a distance from the rotation center to a downstream end of the opening in the rotational direction, and C is a length from the rotation center to the free end of the sheet portion in an unbent state. The upstream end of the opening is lower in a direction of gravitational force than the downstream end at an orientation in use.

A toner conveying device includes a conveying screw and a swinging member. The conveying screw includes a shaft portion and a screw portion spirally wound around the shaft portion. The swinging member has a substantially comb shape and swings between the shaft portion and the screw portion with rotation of the conveying screw, and includes a plurality of overhanging portions arranged side by side at intervals in an axial direction of the conveying screw and a plurality of tip portions, each one of which is bent at a predetermined angle from a free end side of a corresponding one of the plurality of overhanging portions in a direction away from the shaft portion. A width of each one of the plurality of tip portions gradually increases at least from a portion to contact the screw portion toward a free end side of each one of the plurality of tip portions.

A developer accommodating device includes a rotator including a rotation shaft, a collar that rotates together with the rotation shaft, and a bearing rotatably supporting the rotation shaft via the collar. The rotation shaft includes a resin material, and collar including a metal material. The collar includes a collar main portion to be in sliding contact with the bearing, and a flange portion closer to a center of the rotator in an axial direction of the rotator than the collar main portion. The collar main portion has a first outer diameter, and the flange portion has a second outer diameter greater than the first outer diameter of the collar main portion.

A transport member includes a shaft and plural blades that extend around the shaft so as to transport a target object that is to be transported and that is present around the plural blades in a direction in which the shaft extends by rotating with the shaft, the plural blades extending in at least a region of the transport member in the direction in which the shaft extends in such a manner that the plural blades are sequentially out of phase with one another in a direction in which the plural blades rotate. The at least a portion in the direction in which the shaft extends has flexibility.

A developer storage device that stores developer includes a frame having an internal space and an inlet, a partition portion for partitioning the internal space into first and second chambers, the partition portion including a communication port through which the first and second chamber communicate, a conveyance portion arranged in the internal space and configured to convey the developer, and a detection unit detecting an amount of the developer stored in the first chamber. When the amount of the developer in the first chamber is less than a predetermined value, the developer is conveyed to a far side portion of the first chamber by the conveyance portion. When the detection unit detects that the amount of the developer in the first chamber reaches the predetermined value or more, the conveyance portion conveys the developer to the second chamber.

An image forming apparatus includes a toner container, a first conveyance unit, and an apparatus main body. The apparatus main body includes a photosensitive drum, a development roller, a second conveyance unit, a toner conveyance passage, light sensor, an acquisition unit, and a control unit configured to execute an abnormality detection mode. In an abnormality detection mode, the acquisition unit acquires a first acquired value after the driving of the second conveyance unit with the driving of the first conveyance unit stopped. When the first acquired value satisfies a first condition, the acquisition unit further acquires a second acquired value after the driving of the second conveyance unit with the driving of the first conveyance unit stopped. The apparatus main body further includes a notification unit to make notification of the abnormality when the second acquired value satisfies a second condition.

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.