AUTOMATIC DENSITY CONTROL IN A PHOTOCOPYING MACHINE

摘要

A density controlling method for controlling the density of toner applied to the surface of a photosensitive drum of a photocopying machine is disclosed herein. A small area of the drum is irridated with light, and toner is applied thereon. A photo-transistor sensor senses the density of the toner, and a signal produced by the sensor is compared to a reference signal indicative of optimal toner density. The difference signal is then applied through a CPU to control both the bias voltage of the developing system and the speed of the toner motor.