Patent ID: 7709774

Claim:
A method of controlling the light output of a color lighting device with light-emitting sources fixed on a common substrate, each light-emitting source comprising at least one light-emitting diode, each light-emitting source comprising one photosensor that detects the light output only of the associated light source, and each light-emitting source being connected to an analog control circuit that controls the drive of each light-emitting source separately on the basis of a light output detected by the associated photosensor, each control circuit comprising a comparator ( 5 a , 5 b , 5 c ) connected to the associated photosensor, wherein the method comprises: detecting a photosignal that contains information on the actual light output of the single light source, guiding the photosignal to the control circuit, in which the comparator compares the photosignal with a reference signal, whereupon if the photosignal is less than the reference signal the control circuit provides a high output signal that increases the driving signal for the light-emitting source, or if the photosignal is greater than the reference signal the control circuit provides a low output signal that decreases the driving signal for the light-emitting sources.