| 摘要 |
PROBLEM TO BE SOLVED: To make a high voltage generating circuit small, and reduce the generation of noise in polarity inversion of an AC rectangular wave by self- oscillating a resonance circuit with a high frequency generating from a self- oscillating circuit in the start of lighting and applying to a discharge lamp. SOLUTION: In the starting of a discharge lamp 4, a self-oscillating circuit 11 self-oscillates a resonance circuit 31 with a high frequency (for example, about 1 MHz) generated from a high frequency generating circuit 21, high voltage is generated in a capacitor 32, and applied to the lamp 4. When the discharge lamp 4 is lit, the resonance phenomenon of the resonance circuit 31 is eliminated, and self-oscillation stops. After that, the discharge lamp 4 is lit by the power source voltage from an AC rectangular wave generating circuit 3. By using the high frequency, capacities of a current feedback resonance circuit 21, a resonance capacitor 32, and a resonance coil 33 can be made small, and the self-oscillating circuit 11 can be made small. Inductance of each coil and transformer is made low, follow to the AC rectangular wave is made quick, and break off of current in polarity inversion is prevented. |
