| 摘要 |
PURPOSE:To perform a real time control for an electrifying device by estimating a dark decay quantity after a fixed period based on the surface potential of a photosensitive drum in addition to the real quantity of electrifying the surface of the photosensitive drum and also to accurately control the surface potential of the drum in accordance with high-speed copying. CONSTITUTION:A pulse width modulation signal obtained by comparing the detection value of the surface potential of the drum 1 by a scorotron 11 on a secondary side with a reference voltage is inputted in a reference voltage supply circuit 19 provided with correction information guided from a functional relation between a current value flowing in the surface of the photosensitive drum at an electrifying time and the dark decay quantity of the drum surface potential in a developing part, and the potential of the reference voltage is relatively corrected in accordance with a correction value obtained by comparing the duty of the inputted pulse and the correction information so as to be fed back to the comparator 13, and then, the quantity of electrifying the drum surface by the scorotron 10 on the primary side is varied by the duty of the pulse width modulation signal which is obtained by comparing the corrected reference voltage with the detection value of the drum surface potential. |
