Patent ID: 7218065

Claim:
A discharge lamp lighting circuit, comprising: a DC-to-AC converter circuit which receives an input DC voltage to perform DC-to-AC conversion; a starting circuit which supplies a start signal to a discharge lamp; and a control section which controls power output from the DC-to-AC converter circuit, wherein the DC-to-AC converter circuit includes a plurality of switching elements driven by the control section, and a serial resonance circuit including an inductance element or a transformer and a capacitor, and where a resonance frequency of the serial resonance circuit assumed when the discharge lamp is turned off is represented as “Foff”, a driving frequency of the switching elements assumed immediately before the discharge lamp is turned on is represented as “f 1 ”, the resonance frequency of the serial resonance circuit assumed when the discharge lamp is turned on is represented as “Fon”, and the driving frequency of the switching elements assumed when the discharge lamp is turned on is represented as “f 2 ”, before the discharge lamp is turned on, a driving control of the switching elements is performed so that the driving frequency gradually approaches Foff and the start signal is supplied to the discharge lamp, and after the discharge lamp initiates to be turned on, the driving frequency is continuously shifted from f 1 to f 2 so that the driving frequency of the switching elements is shifted to a frequency range higher than Fon.