Patent ID: 7315139
Filing Date: 2008-01-01
Classification: H05B

Abstract:
1. A light source comprising: first, second, and third component light sources; first, second, and third primary drive circuits, each primary drive circuit providing an average current to a corresponding one of said component light sources; a photodetector that generates three measurement signals representing, respectively, an intensity of light generated by said component light sources in three wavelength bands; a processor that generates three intensity signals representing the intensity of light produced by each of said first, second, and third component light sources, respectively, from said measurement signals; and a servo loop that adjusts said drive circuits so as to maintain said intensity signals at corresponding target values, wherein one of said component light sources comprises first and second LEDs and a secondary drive circuit, said secondary drive circuit being connected to said third drive circuit and providing first and second drive currents to said first and second LEDs, respectively, said first and second drive currents being in a fixed ratio to one another and having values determined by said average current from said third primary drive circuit.