| 摘要 |
PURPOSE:To eliminate prerotation which is not associated with image forming and to shorten an image forming time. CONSTITUTION:In a four-color full-color printer, a potential sensor which detects the surface potential of a photosensitive body after an electrostatic latent image is formed is arranged. By executing the pre-multi-rotation before copying can be executed after a switch is turned on, for example, potential difference between the first rotation and the second rotation of the photosensitive body is detected. Based on the information of the potential difference, the grid bias voltage Vg2 of the first rotation of the drum after the copying is started is set to be higher than the second and subsequent grid bias potential Vg1 Thus, the surface potential after the electrostatic charge of the first rotation can be made equal to the surface potential V0 of the second and subsequent rotation. Therefore, the prerotation for stabilizing the electrostatic charge property, the sensitivity or the like of the photosensitive body which is conventionally required need not be executed and the image can be formed from the first rotation. Besides, image quality is not deteriorated. |
