Patent ID: 7656100

Claim:
A system ( 100 ) for controlling light output of a lighting system and comprising: a calibration matrix ( 104 ) configured to transfer a desired colour and brightness to a set-point ( 110 ); a light mixing circuit ( 116 ) comprising a plurality of light sources configured to provide a mixed light output ( 102 ); a controller ( 108 ) coupled to said calibration matrix ( 104 ) and configured to receive said set-point ( 110 ), and coupled to said light mixing circuit ( 116 ) and adapted to generate a driving signal ( 120 , 122 ) for said light mixing circuit ( 116 ), and said controller ( 108 ) comprising a rescale unit ( 118 ) configured to measure said driving signal ( 120 , 122 ) and to rescale said driving signal ( 120 , 122 ) when said driving signal ( 120 ) exceeds a predetermined signal threshold, and characterized in that said light mixing circuit ( 116 ) further comprises a temperature sensing means configured to measure temperature of a heat-sink ( 202 ) supporting said plurality of light sources and adapted to generate a heat-sink temperature signal ( 206 ), and in that said controller ( 108 ) further comprises a calculation unit ( 204 ) configured to receive said heat-sink temperature signal ( 206 ) and to calculate a junction temperature for each of said plurality of light sources from said heat-sink temperature signal, and is adapted to generate said driving signal ( 120 , 122 ) as a function of said junction temperature.