Patent ID: 8110995

Claim:
An illumination system, comprising: (i) a plurality of light sources generating light of mutually different colors, each provided with an associated driver; (ii) a controller for generating control signals for controlling the respective drivers; temperature feed forward means for establishing a temperature feed forward correction mechanism; and (iii) flux feedback means for establishing a flux feedback correction mechanism; wherein the controller is capable of operating in a first mode of operation wherein both the temperature feed forward correction mechanism and the flux feedback correction mechanism are active; wherein the controller is capable of operating in a second mode of operation wherein the temperature feed forward correction mechanism is active and the flux feedback correction mechanism is inactive; and wherein the controller is configured to monitor the duty cycles of the control signals and to select its said first or second mode of operation on the basis of said duty cycles, wherein controller, when operating in the first mode of operation, on finding that at least one duty cycle is less than a predetermined value, is configured to switch over to the second mode of operation; and wherein the controller, when operating in the second mode of operation, on finding that all duty cycles are higher than said predetermined value, is configured-to switch over to the first mode of operation, wherein said flux feedback means comprise calculating means for calculating a flux error signal on the basis of comparing a target flux signal and a measured flux signal with each other, and wherein said flux feedback means comprise compensating means receiving a correction signal derived from said flux error signal and calculating a corrected control signal from an intermediary control signal value.