Patent attributes
The present invention provides a method and apparatus for optical feedback control for an illumination device, wherein the control signal for each array of one or more light-emitting elements corresponding to a particular color, is independently configured using a modification signal whose frequency is different for each color. Electronic filters whose center frequencies are substantially equal to the modification signal frequencies of the drive currents for the light-emitting elements are used to discriminate between the radiant flux corresponding to each of the different colors of light-emitting elements, from a sample of the mixed radiant flux output collected by one or more optical sensors. The output of an individual electronic filter is substantially directly proportional to the radiant flux output of the light-emitting elements of the associated color, which together with the desired luminous flux and chromaticity of the output light, the controller can use to adjust the control signals.
