| 摘要 |
PURPOSE:To prevent sticking of excess toner to a photosensitive drum and to prolong service life of a cleaner by providing a developing bias delay shutting circuit which retains impressing of developing bias voltage for a fixed period of time when an unexpected failure occurs in a driving system of a photosensitive drum and a means to brake rotation of the photosensitive drum. CONSTITUTION:The developing bias voltage VDE is prevented from becoming 0V after the failure occurrence, a constant voltage is retained for a fixed period of time, and the stopping distance of the photosensitive drum 1 is kept constant. In this case, variation of backside potential VDE of a developing sleeve is delayed and retained for a fixed period of time by the developing bias delay shutting circuit 33. And on the other hand, a processor 31 and a motor driver IC41 to make the stopping distance of the photosensitive drum constant are provided. Thus, when unexpected failure such as a sudden stop of a motor 42 driving the photosensitive body 1 during printing occurs or when accidents such as electrical power source being suddenly cut off occur, carrier 12 or excess toner 11 are prevented from sticking to the photosensitive drum 1, and the service life of the cleaner is attained. |
