Patent ID: 8588657

Claim:
A developing device comprising: a developer tank that contains developer, the developer tank including a partition, an internal space of the developer tank being partitioned by the partition into a first conveying path extending along a longitudinal direction of the partition, a second conveying path being opposite to the first conveying path with the partition interposed therebetween, a first communication path through which the first conveying path and the second conveying path communicates with each other on a side of one end in the longitudinal direction of the partition, and a second communication path through which the first conveying path and the second conveying path communicates with each other on a side of the other end in the longitudinal direction of the partition; a first developer conveying section that is disposed in the first developer conveying path and conveys the developer in the developer tank from the side of the other end toward the side of the one end in the longitudinal direction of the partition, the first developer conveying section including: a spiral blade that is spirally wound on a side surface of an imaginary column and conveys the developer by rotation around an axial line of the imaginary column, a rotation tube that has a cylindrical shape, surrounds an outer peripheral portion of the spiral blade and rotates together with the spiral blade, the rotation tube having an inflow opening portion through which the developer flows in and which is disposed in a circumferential wall of the rotation tube on the side of the other end in the longitudinal direction of the partition, and an outflow opening portion through which the developer flows out and which is disposed on the side of the one end in the longitudinal direction of the partition, and a developer guiding blade that is fixed to an outer circumferential wall of the rotation tube, and guides the developer existing on an external side of the rotation tube to the inflow opening portion by rotation of the rotation tube; a second developer conveying section that is disposed in the second conveying path and conveys the developer in the developer tank from the side of the one end toward the side of the other end in the longitudinal direction of the partition; and a developing roller that bears the developer and supplies the developer to an image bearing member, the developing roller facing the second conveying path.