| 摘要 |
PROBLEM TO BE SOLVED: To provide a ballast of a discharge lamp which has high power efficiency in practical use and exerts excels in start of the discharge lamp. SOLUTION: This ballast of a discharge lamp includes a booster circuit to convert a low DC voltage given by a power supply into a high DC voltage 1 and a driver circuit to convert the DC voltage V1 from the booster circuit into voltage of approx. rectangular form, wherein a large capacitance capacitor, a coil and a small capacitance capacitor are connected in series to the output side of the driver circuit, and the discharge lamp is connected parallel to the ends of the small capacitance capacitor so that a resonance circuit is formed, wherein a lighting sensing circuit is provided to sense that the lamp is on, whereby the lighted condition of the lamp is sensed by the lighting sensing circuit, and when the lamp is off, the booster circuit is controlled so that the output voltage is raised to a start voltage V2 which is higher than the DC voltage V1 of the booster circuit when the lamp is in the steadily lighting condition. |
