The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 03, 2002
Filed:
Sep. 15, 2000
Thomas M. Marshall, Hartsdale, NY (US);
Michael D. Pashley, Cortlandt Manor, NY (US);
Koninklijke Philips Electronics N.V., Eindhoven, NL;
Abstract
A luminaire comprises an array of LEDs that include at least one LED in each of a plurality of colors. Supplied to the LEDs for each color is an electrical current that, during a measuring period, comprises a measuring drive pulse having at least a first boost portion and a turn-off portion. The LEDs relating to each color have a light output which has a nominal continuous value during ordinary operation and increases during the boost portion and is interrupted during the turn-off portion. The array has a combined light output when current is supplied to all of the LEDs in the array. A photodiode is arranged to measure the combined light output which selectively turning off the electrical current to the LEDs so that the photodiode measures the light output for each color separately in response to the measuring drive pulse. The average light output during the measuring period is substantially equal to the nominal continuous light output during the ordinary operation so as to avoid visible flickers.