| 摘要 |
PURPOSE:To obtain pictures of good quality with a stable density by detecting the surface temperature of an image carrier and counting rotations of the image carrier and controlling a preexposure device of the image carrier on a basis of both detected values to control the exposure. CONSTITUTION:A control part controls a voltage converter A in accordance with a signal from counter, which detects the number of rotation of an image carrier 2 by a pulse detector 30, by a preliminarily determined program to control the voltage impresses to a preexposure light source 20. The control part controls a voltage converter B in accordance with the value, which is obtained by detecting the temperature of a photosensitive body 2a of the image carrier 2 by a sensor 40, by a preliminarily determined program to control an overall impressed voltage to the preexposure light source 20. The preexposure light source is arranged between a cleaning device (not shown in figure) and an electrostatic charge electrode to perform exposure with the controlled voltage. Thus, the potential of a developing part is kept constant independently of the repeat number of copying or the temperature of the photosensitive body to obtain copies of good quality with a stable density. |
