Patent ID: 8013533

Claim:
Method for determining drive values for driving a lighting device at a desired brightness and color, said lighting device comprising of a plurality of light emitting diodes (LEDs) of at least two different colors, said method comprising the steps of: determining a first luminous flux weight ratio based on the desired color and a first drive current for driving each of the differently colored LEDs; determining a first luminous flux for each of the differently colored LEDs based on the desired brightness and the first luminous flux weight ratio; comparing, for each of the differently colored LEDs, the first luminous flux with a nominal luminous flux for a plurality of different drive currents; selecting, for each of the differently colored LEDs, a preferred drive current that at least can produce the first luminous flux; determining a second luminous flux weight ratio based on the desired color and the selected drive currents for each of the differently colored LEDs; determining a second luminous flux for each of the differently colored LEDs based on the desired brightness and the second luminous flux weight ratio; and determining a duty cycle for each of the differently colored LEDs at the selected drive currents, wherein the selected currents at the determined duty cycles produces the second luminous flux for each of the differently colored LEDs.