Patent ID: 8805222

Claim:
An image developing device comprising: a developer supporting body configured to support a developer and configured to convey the developer to a portion facing a latent image supporting body; a first conveyance path in which a first conveyance member is arranged, the first conveyance member being configured to convey the developer along an axis line direction of the developer supporting body; a second conveyance path in which a second conveyance member is arranged, the second conveyance path being configured to convey the developer in a direction opposite to the developer conveyance direction by the first conveyance member, the second conveyance member being arranged above the first conveyance path; and a partition member configured to partition the first conveyance path and the second conveyance path and that has a first communication port and a second communication port, the first conveyance path and the second conveyance path being configured to communicate with each other at a first end portion and a second end portion in the axis line direction through the first communication port and the second communication port, wherein the image developing device includes a developer amount detection unit that includes an optical detection unit arranged in the second conveyance path and configured to optically detect an amount of the developer in the image developing device, and wherein a second developer conveyance speed by the second conveyance member is greater than a first developer conveyance speed by the first conveyance member so that the developer is caused to accumulate in the vicinity of the developer amount detection unit of the image developing device.