| 摘要 |
PURPOSE:To prevent the toner of a cleaning means from being stuck to a photosensitive body, etc., by setting the bias output of a developing at a bias so as to move the toner to a supporting drum side when a beltlike photosensitive body is automatically exchanged. CONSTITUTION:A photosensitive drum is constituted by winding a photosensitive sheet on the supporting drum 905, and the automatic take-up and winding of the photosensitive sheet can be automatically carried out on the drum 905. The recessed part 905a of the drum 905 is a joint not having an image formation, so that a joint sensor for detecting the recessed part is provided. For preventing the sticking of unnecessary toner on the drum 905 when the photosensitive sheet is exchanged, a developing bias, etc., are controlled. In other words, it is judged whether the joint of the photosensitive drum is opposite to the developing unit or not. In this example, negative electrifying toner is used, and a potential is lowered to about -100V by an image exposure. While the joint faces the developing unit, the developing bias is set to +200V at the time of exchanging the photosensitive body. |
