| 摘要 |
PURPOSE:To surely detect by providing a dam on the outside circumference of at least one end part of a developing sleeve in such a manner that part of the developer on this developing sleeve can flow in, and projecting light from a light emitting device onto the developer storage part of this dam. CONSTITUTION:A dam 6 is provided to one end part of a developing sleeve. This dam 6 is formed by winding and bonding a plate material of, for example, ''Sofran '', urethane rubber, etc., about 1/2 circumference on the outside circumference of the end part of a developing sleeve 2. A slope is made to the end part 6-1 of the dam 6 to smooth the flowing-in of the developer 4 into the part other than the dam 6, that is, a developer storage part 8. A photodetecotor 11 outputs a constant electric signal when it receives reflected light from a light emitting device such as light emitting element which detects the presence of its reflected light. Thereby, the presence of the developer is directly detected, hence sure detection is made possible. |
