An electrostatic reproduction machine has an improved control system therein for controlling the operation of a toner dispenser. The system which includes a light source and a light sensitive device, compares the difference between the amount of light reflected from an undeveloped area of a photoreceptor...http://www.google.com/patents/US4082445?utm_source=gb-gplus-sharePatent US4082445 - Toner control system for an electrostatic reproduction machine
