Patent ID: 8878443

Claim:
A light engine ( 100 ; 200 ; 300 ; 400 ) comprising: an array of LEDs comprising at least one first string ( 102 ; 402 ) of first LEDs ( 102 A-D; 402 A-B) connected in series which, when energized, output light having a first wavelength range and comprising at least one second string ( 104 ; 404 ) of second LEDs ( 104 A-D; 404 A-C) connected in series which, when energized, output light having a second wavelength range different from the first wavelength range, wherein said at least one second string ( 104 ; 404 ) is connected in series with said at least one first string ( 102 ; 402 ); a power supply ( 106 ; 406 ) connected to the array for connection to a power source for energizing the LEDs; a control circuit ( 108 ; 206 ; 306 ; 406 ) connected to the array comprising a temperature variable resistance component ( 202 ; 302 ; 410 ) and a switch ( 204 ; 304 ; 416 ) selectively connecting the temperature variable resistance component to the array, the control circuit controlling the switch ( 204 ; 304 ; 416 ) as a function of a temperature circuit ( 208 ; 308 ) indicative of the temperature of at least one of the LEDs, wherein the control circuit limits the current applied to at least some of the LEDs ( 104 ; 402 , 404 ) during initial energization of the LEDs prior to steady-state operation of the LEDs whereby variations over time of a color correlated temperature (CCT) of output light of the energized array are reduced.