| 摘要 |
PURPOSE:To use a photosensitive body in a copying device provided with plural developing devices without lowering a copying efficiency by changing the relative speed of the photosensitive body and the developing device which is used for development according to the developing device which is used for development. CONSTITUTION:In order to obtain the potential of the surface of the photosensitive drum 1 corresponding to all white of an original in the positions of the developing devices 31 and 32, it is necessary to lower the rotary speed of the photosensitive drum 1-150mm/s, especially, in the 1st developing device 31 since the electric potential is not fully lowered by the time exposing position attains the developing devices 31 and 32 if the rotary speed of the photosensitive drum 1 is comparatively large. Thus, the titled device uses a carrier-life type one which can perform high speed copying as the photosensitive drum and provides plural developing devices, then it changes the rotating speed of the photosensitive drum according as which developing device is used. Therefore, in case of using black toner whose use frequency is high, copying can be performed at high speed and also color toner can be used by lowering the rotating speed of the photosensitive drum. |
