Patent ID: 8030856
Filing Date: 2011-10-04
Classification: H05B

Abstract:
1. A discharge lamp lighting device comprising: an oscillation control circuit that uses a variable capacitance diode to determine an oscillation frequency based on a DC dimming control voltage; an LC series resonant circuit that is connected to a half bridge circuit or a full bridge circuit; a hot cathode type discharge lamp that has filaments respectively arranged at both ends; and a load capacitor that is connected to one ends of the two filaments and determines a filament current on a basis of said oscillation frequency, wherein: said LC series resonant circuit has a resonant capacitor that is connected to other ends of the two filaments and determines a tube voltage of said discharge lamp on the basis of said oscillation frequency; and said oscillation control circuit switches ON/OFF current flowing into any of two or more oscillation capacitors including said variable capacitance diode to thereby change said oscillation frequency, and upon dimmed operation, by changing said DC dimming control voltage, changes said oscillation frequency to decrease a tube current of said discharge lamp and also increase said filament current.