Patent ID: 6495964
Filing Date: 2002-12-17
Classification: F21V,F21W,F21Y,G01J,G02B,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 including a measuring drive pulse having a measuring period that comprises a â€œturn offâ€  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 is interrupted during said â€œturn offâ€  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 at least one of the LEDs in the array; and means for selectively turning off the electrical current to one of said LEDs so that said photodiode measures the light output for each color separately in response to said measuring drive pulse.