| 摘要 |
PURPOSE:To prevent the fading of an electric discharge lamp and enable the stable lighting thereof by feeding a high-frequency electric power for lighting the electric discharge lamp via the first high-frequency conversion circuit, and feeding intermittently a high-frequency electric power for starting the electric discharge lamp and maintaining the lighting thereof via the second high-frequency conversion circuit. CONSTITUTION:A variable high-frequency feeder circuit 3 comprises a chopper circuit 1 for converting a commercial a.c. power supply AC to a variable d.c. power supply E1, and a high-frequency conversion circuit 2 for generating a high-frequency electric power. The second high-frequency conversion circuit is constituted for applying voltage for starting and lighting maintenance of an electric discharge lamp la to the high-frequency conversion circuit 2 from the second power supply E2 via a switching element SW. And in an ordinary condition, the electric discharge lamp la is dimmered and lit with a high-frequency electric power of a low voltage amplitude from the first electric power E1. Also, the electric discharge lamp la is started and maintained to be lit with a high-frequency electric power of a high voltage amplitude intermittently fed from the second electric power supply E2. According to the aforesaid construction, it is possible to prevent the fading of the electric discharge lamp la and turn on the lamp la stably at all times. |
