| 摘要 |
PURPOSE:To start a discharge lamp certainly even in case once dropped power supply is recovered by restitution and changing-over is made from an emergency power supply to the normal power supply by performing power supplying to a timer means for a control means, which changes the output of the first high frequency wave generating device, through a changeover means. CONSTITUTION:When a normal power supply 1 is put on, the first high frequency wave generating device 10 oscillates, and the output voltage therefrom is supplied to a discharge lamp 11. When the power supply 1 decays, it is sensed by a sensing means 6, and a changeover means 7 changes over the connection of the lamp 11 from the first device 10 to the second high frequency wave generating device 20. A voltage monitoring device 46 actuates another changeover means 47 and supplies the output of an emergency power supply 40 to the second device 20. Thereby the lamp 11 is lighted with a relatively decreased power. On the other hand, the input power is shut off by the changeover means 7 and the timer means 30-1 of a control device 30 discharges the electric charges quickly through a diode, resistor, etc. If then the normal power supply 1 is restituted, the lamp 11 is changed over form the second 20 to the first device 10 through the action of the means 6, 7, and the operation of the device 20 is stopped by the devices 46, 47. |
