| 摘要 |
PURPOSE:To provide a small and lightweight lighting device for a discharge lamp, in which occurrence of acoustic resonant phenomenon is precluded, by feeding the high-frequency output rectified by a rectifier circuit to a low-frequency inverter, thereby converting into a rectangular wave of low frequency, and feeding it to a discharge lamp in the form of high-voltage pulses via a trigger circuit. CONSTITUTION:Output of a high-frequency inverter H is fed to a rectifier circuit D1, composed of diodes in bridge connection, through a ballast CH of, for ex., a capacitor or a choke coil. The output of this rectifier circuit D1 is fed to a low-frequency inverter LF, and a low-frequency inverter LF emits a rectangular wave with as low a frequency as not causing occurrence of acoustic resonance phenomenon within a discharge lamp DL. A trigger circuit TG is furnished, which receives this rectangular output and emits pulses with as high a voltage as capable of starting the discharge lamp DL, which is thus lit up with rectangular waves at a frequency in the degree which does not allow occurrence of the acoustic resonance phenomenon. This accomplishes a small and lightweight lighting device, with which lighting can be maintained with frequencies not generating acoustic resonance phenomenon. |
