Developing unit including developer conveyance system having supply path, recovery path, and agitation path, process cartridge including developing unit, and image forming apparatus including process cartridge

摘要

A developing unit includes a developer bearing member, a developer transporter, a developer conveyance system for directing the developer, including a supply path, a recovery path, and an agitation path, a developer supply opening through which the developer is supplied to the developer conveyance system, a developer supply device for supplying the developer from the developer supply opening to the developer conveyance system, a developer discharge device for discharging the developer outside the developing unit, a developer level rise detector for detecting increase in a level of the developer between the downstream end of the recovery path facing the developer bearing member in the direction of developer transport and a portion of the agitation path where the agitation path receives the collected developer from the recovery path, and a controller for controlling the developer discharge device based on the detection result provided by the developer level rise detector.