Low power control circuit for LED field intensity control - supplies LEDs with pulse trains whose keying ratio varies in accordance with control signal

摘要

The LED's are mounted in a field for image reproduction, esp. for position finders. Control signals representing brightness information are applied to comparators, and a common function generator is connected to their other inputs. The generator voltage continuously rises and/or falls, and serves as a reference signal (UR). A pulse train appears at the outputs of the comparators whose keying ratio varies in accordance with the control voltages (US). This pulse train is used as the LED voltage (UL).