A LUMINAIRE DRIVE CIRCUIT

摘要

A luminaire drive circuit (1) comprises an AC to DC power supply (2) delivering DC power to rails (3), and a plurality of LED drive circuits (4) connected across the rails to receive DC power. Each LED drive circuit (4) comprises a plurality of LEDs (7) in series and a voltage and current controller (6) for controlling current through the LEDs and a voltage across the LEDs which is less than the voltage across the rails. In one example, each LED circuit (4) has a dedicated sensor (52) to detect proximity of an illuminated object. This allows control of illumination intensity both for energy efficiency and visual effect. The proximity sensor may be simply a photodiode (52) mounted to detect extent of light reflected from the objects (Fig. 5), thus avoiding need for a self-contained proximity sensor such as one of the ultrasonic type.