Patent ID: 8831483

Claim:
A developing device for developing an electrostatic latent image formed on an image bearing member by supplying a stored developer to the image bearing member, comprising: a developer tank that stores a developer; a partition wall that divides an internal space of the developer tank into a first conveying path extending along a longitudinal direction of the partition wall, a second conveying path located toward the image bearing member, which is opposed to the first conveying path, with the partition wall, a first communication path for providing communication between the first conveying path and the second conveying path at a side of one longitudinal end of the partition wall, and a second communication path for providing communication between the first conveying path and the second conveying path at a side of another longitudinal end of the partition wall; a first developer conveying section that is disposed in the first conveying path and conveys a developer in the developer tank from the side of the another longitudinal end to the side of the one longitudinal end, the first developer conveying section including a plurality of individual inner spiral blade pieces which together have a spiral shape which is wound around a side surface of an imaginary circular column and conveys the developer toward the side of the one longitudinal end from the side of the another longitudinal end by rotation around an axial line of the imaginary circular column, the plurality of inner spiral blade pieces being disposed so as to be spaced from each other in an extending direction of the spiral shape, and a rotation tube which surrounds an outer circumferential portion of the plurality of inner spiral blade pieces, and rotates with the plurality of inner spiral blade pieces, the rotation tube having an admission port portion which is formed with a hole for admitting the developer into the rotation tube and is disposed on the side of the another longitudinal end of the partition wall, and a discharge port portion which is formed with a hole for discharging the developer from an inside of the rotation tube and is disposed on the side of the one longitudinal end of the partition wall; and a second developer conveying section which is disposed in the second conveying path and conveys a developer in the developer tank from the side of the one longitudinal end to the side of the another longitudinal end.