| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device preventing a discharge lamp from flickering or dying out by making it easy to secure a relatively high lamp voltage even in the event of deep dimmed lighting, and reduced in cost by simplifying its circuit configuration. SOLUTION: In this discharge lamp lighting device, the use of a switching element Q1 is partly shared by a chopper circuit 8 for reducing distortion of input current from an alternating-current power supply AC and by an inverter part 2 for high frequency generation, a direct-current voltage obtained at a smoothing circuit C4 by the function of the chopper circuit 8 is used as the power source of the inverter part 2, the oscillation output of the inverter part 2 is supplied to a discharge lamp via a resonance circuit 3, and the discharge lamp is dimmed by the change of a resonance voltage caused by varied frequency. The on-duty of the switching element Q1 in the chopper circuit 8 is decreased as an operating frequency increases so that the output voltage of the smoothing circuit becomes high at the time of full lighting of the discharge lamp and becomes lower as the optical output of the discharge lamp decreases. |
