| 摘要 |
PURPOSE:To control accurately the amount of charging of a photoreceptor without reference to a sensor output error due to oscillation of a copying machine and a seam of the photoreceptor, by using only an electrostatic potential sensor output in specific time when an optical system reciprocates stably, and then controlling the amount of charging of the photoreceptor. CONSTITUTION:Assuming that an increase in the output of a sensor 7 causes a decrease in control signal outputted from a sequence controller 12, the output of a differential amplifier 14a increases and an input signal to a comparator 14b also increases, so the high-level period of a signal from the comparator 14b is shortened and the conduction period of a transistor (TR) 14d is also shortened, so that a high voltage developed at the secondary side of a high-voltage transformer 14e drops. Therefore, a voltage applied to a charging corotron 6 is low and the amount of charging of the photoreceptor is reduced. On the other hand, when the amount of the charging of the photoreceptor is reduced and the output of a sensor 8 decreases, the conduction period of the TR14d in a high-voltage power source 14 is extended, so the voltage from the power source 14 is high and the amount of discharging of the charging corotron 6 increases, thereby increasing the amount of charging of the photoreceptor. |
