| 摘要 |
PURPOSE:To obtain smooth dimming with no flickering and shorten the conductive period of a dimming device by providing an auxiliary power source circuit on a lighting device, detecting the lighting state of a discharge lamp with the potential of this output voltage, and controlling the output of a high-frequency generating circuit. CONSTITUTION:An AC power source 1 is turned on, the full-wave rectification output of a rectifying circuit 2 is outputted to a high-frequency generating circuit 3. A current is fed from the positive side output of the circuit 2 to the base of a transistor 20 via resistors 25 and 24 to turn transistors 20 and 16 on. When the transistor 16 is turned on, the high-frequency voltage is generated by an oscillation transformer 6, a discharge lamp 4 is lighted, an auxiliary power source circuit 11 rectifies and smoothes the high-frequency voltage of the transformer 6 with a rectifying circuit 12 and a capacitor 13 and feeds it to the high-frequency generating circuit 3 as the DC voltage. A current is fed from the positive side output of the circuit 11 to the base of the transistor 20 to turn the transistor 20 on, the circuit 3 is stably operated. The circuit 3 can be stopped when the lamp is turned off. |
