Patent ID: 8896221

Claim:
A lighting device for one or more semiconductor light emitting elements, comprising: a series circuit of two switching elements which are alternately turned on using different square wave voltage signals, respectively, the series circuit being connected in parallel to a direct current (DC) input power source; and a reactance circuit connected between a connection node of the two switching elements and one end of the DC input power source through a capacitor, an output of the reactance circuit being supplied to the semiconductor light emitting elements through a rectifier circuit, wherein a dimming operation of the semiconductor light emitting elements is performed by varying a ratio of ON periods of the two switching elements, wherein the ON periods of the two switching elements are determined by the square wave voltage signals, respectively, wherein the number of the semiconductor light emitting elements is 2, and the rectifier circuit includes two half-wave rectifier circuits of reverse polarity, which are respectively connected to the semiconductor light emitting elements having different color temperatures, and wherein a color temperature of mixed light is changed by controlling the ratio of the ON periods of the two switching elements, and luminance of the mixed light is changed by controlling a switching frequency of the two switching elements.