| 摘要 |
PURPOSE:To stabilize a discharge current, by providing a ring-shaped conductor partially on the surface of a photosensitive drum through an insulator and providing a contact which is always brought into contact with this conductor with a required contact pressure to detect the discharge current of the photosensitive drum. CONSTITUTION:A ring-shaped conductor 4 is provided partially on the surface of a photosensitive drum 2 through an insulator 3. A contact 5 is provided which is always brought into contact with the conductor 4 with a required contact pressure to detect the discharge current of the photosensitive drum 2. Meanwhile, a controlling circuit 10 of a DC corona discharging consists of a comparing circuit 11, a reference voltage setter 12, and a DC bias circuit 13 controlled by a DC bias voltage. By this constitution, a high voltage applied to the corona discharger is controlled to generate always a required stable discharge current of the photosensitive drum, and thus, the function of the copying machine is held for a long time. |
