| 摘要 |
PURPOSE:To provide a discharge lamp lighting device which can prevent the temperature rise and loss of a switching element in an abnormal lighting mode and can hold a high-frequency voltage roughly constant with respect to the supply voltage fluctuation of an AC power supply, the high-frequency voltage being supplied to a discharge lamp. CONSTITUTION:A voltage obtained from the full-wave rectification of the AC voltage of an AC power supply 1 by a rectifier circuit 3 is boosted by a booster chopper circuit 2 and stored in a smoothing capacitor C1 as a roughly constant DC voltage, which is then converted into a high-frequency voltage by the alternate turn-on and -off of transistors Q1, Q2 and applied to each end of a discharge lamp La. The transistors Q1, Q2 are turned on and off by the supply to base of currents produced in the secondary windings n22, n23 of a current transformer CT. Therefore, the temperature rise and loss of a switching element can be prevented in an abnormal lighting mode, and the high-frequency voltage supplied to the discharge lamp can be held roughly constant with respect to the supply voltage fluctuation of the AC power supply. |
