To provide a discharge lamp lighting device in which a discharge lamp and a inverter circuit are not stressed to a great extent in the case of lighting and diming the discharge lamp.
In the case of lighting and dimming fluorescent lamps FL1, FL2, a high-level voltage is inputted from an operation amplifier 21 by a frequency twice as much as that of a commercial alternating current power source (e), based on the wave form thereof. A transistor Q3 is controlled on-off in synchronism with a power source voltage by the frequency twice that of the power source (e). Dependent on the on-off control of the transistor Q3 an oscillation control part 19 performs frequency modulation between a lighting frequency f1 and a put-off frequency f2 synchronized with an output voltage of the power source (e) by the frequency twice that of the power source (e). By changing an output voltage of an inverter circuit 17, lamp currents for putting on an off fluorescent lamps FL1, FL2 are outputted alternately and repeatedly in synchronism with the output voltage of commercial alternating current power source (e), and accordingly the fluorescent lamps FL1, FL2 are put on and off for the lighting and dimming operation by the frequency twice that of the power source (e).
MITA KAZUTOSHI
SHIMIZU KEIICHI
TAKAHASHI KEIJI
