| 摘要 |
PROBLEM TO BE SOLVED: To surely and stably light a discharge lamp according to the state of the lamp by detecting lamp extinguished time, controlling the term setting of one period of applying AC voltage soon after lighting, and controlling lamp current setting. SOLUTION: A control circuit 5 detects the time elapsed after operation of lights-out based on the terminal voltage of a capacitor with a time detecting circuit comprising a CR charge/discharge circuit. Since the shorter lights-out, the hotter a lamp, a driver 6 of an inverter 3 is controlled, the term of one period of AC voltage soon after lighting, supplied to the lamp is lengthened, lamp voltage information and lamp current information are inputted, a D/D converter 1 is controlled, and the shorter the lights-out, the lower the lamp current of one period soon after lighting. Thereby, excess power supply in the hot state is prevented. In a lamp cooled state after long lights-out, the term of one period is set shorter, and lamp current is set higher to surely keep lighting at the activation of the lamp. |
