Patent ID: 8896516

Claim:
A light emission control circuit for driving and controlling a light source having a plurality of light emitting device groups for emitting a plurality of colored lights, connected in parallel to one another, each group comprising a plurality of light emitting devices for emitting a same colored light and being connected only serially to one another, said light emission control circuit comprising: a constant current circuit connected serially to only a specified light emitting device group having a highest whole forward voltage required to obtain a specified light emission intensity, out of said plurality of light emitting device groups; a power source circuit to apply its output voltage to said specified light emitting device group and said constant current circuit connected serially to one another, and other said light emitting device groups; a current detecting unit to detect only a current to be supplied to said specified light emitting device group out of said plurality of light emitting device groups; a power source controlling unit to control said constant current circuit and said power source circuit based on a current detected by said current detecting unit and a current set in advance so that said forward voltage is applied to said specified light emitting device group; and a chromaticity adjusting unit to adjust chromaticity of illuminating light emitted from said light source, wherein said power source controlling unit comprises: an oscillator to generate a triangular wave signal having a specified period and amplitude, a comparator to compare said triangular wave signal inputted from said oscillator with a detecting signal corresponding to a current detected by said current detecting unit and to output a high-level or low-level signal according to magnitude of said triangular wave signal and said detecting signal, thereby controlling said power source circuit, a current value adjusting section to determine a set value of a current to be supplied to said specified light emitting device group, and a current value setting section to control said constant current circuit and said oscillator based on said set value of a current.