| 摘要 |
PURPOSE:To provide an electric discharge lamp lighting device which can adjust power supplied to an electric discharge lamp by fixing the on duration of a switching element and then varying the off duration thereof within a certain range being capable of doing the zero voltage switching thereof. CONSTITUTION:An operating condition detector circuit 19 which detects the operating conditions of a circuit is provided for supplying the output thereof to an off duration decision circuit 20 which can vary the off duration of a transistor 14 at a certain range and then supplies an off duration decision result signal to a first multiplexer 21. Besides, an on duration decision circuit 22 which decides the on duration of the transistor 19 to attain a fixed value is provided for supplying an on duration decision result signal therefrom to a second multiplexer 23. And the transistor 14 is subjected to its own switching action according to the off duration decided by the off duration decision circuit 20 and the on duration decided by the on duration decision circuit 22. The adjustment of power supplied to an electric discharge lamp 17 can thus be made easily by varying the off duration of the transistor 14. |
