Patent ID: 6445139
Filing Date: 2002-09-03
Classification: F21V,F21W,F21Y,G08G,H05B

Abstract:
A luminaire comprising:an array of LEDs comprising at least one LED in each of a plurality of colors; means for supplying electrical current to said LEDs in each said color, said electrical current having a measuring period that comprises a measuring drive pulse having at least a first boost portion and a turn-off portion, said LEDs in each said color having a light output, such that said light output has a nominal continuous value during ordinary operation and increases during said boost portion and is interrupted during said turn-off portion, and the array having a combined light output when current is supplied to all of the LEDs in the array; a photodiode arranged to measure the light outputs of all the LEDs in the array; and means for selectively turning off the electrical current to said LEDs so that said photodiode measures the light output for each color separately in response to said measuring drive pulse.