Patent ID: 6630801
Filing Date: 2003-10-07
Classification: G09G,H05B,Y10S

Abstract:
A method of controlling an LED luminary including red, green and blue (RGB) light emitting diodes (LEDs) driven by forward currents to produce a mixed color light comprising the steps of:measuring an output signal of a filtered photodiode for each of the red, green and blue LEDs of the LED luminary; measuring an output signal of an unfiltered photodiode for each of the red, green and blue LEDs of the LED luminary; calculating a photodiode output signal ratio by dividing the output signal for the filtered photodiode with the output signal of the unfiltered photodiode for each of the red, green and blue LEDs; utilizing the photodiode output signal ratio to determine chromaticity coordinates for each of the red, green and blue LEDs; and adjusting the forward currents for each of the red, green and blue LEDs to produce a desired color light.