| 摘要 |
PURPOSE:To make small the configuration of a discharge lamp lighting circuit and shorten the lighting start time by shortcircuiting the filament electrodes of a discharge lamp by a switching means with putting-on of the main power supply, and bypassing part of the high frequency current of a high frequency inverter by an inverter means. CONSTITUTION:When a DC power supply 1 is put on by the operational part 11, a high frequency inverter 2 feeds high frequency current to the output terminal 6. The operational part 11 gives a lighting command to a DC preheat circuit 3 and dimming circuit 4 via a CPU 10, and the preheat circuit 3 gives a certain voltage DC current to the output terminal 6. The dimming circuit 4 turns on a switching circuit SW to preheat the filament. The CPU 10 emits a lighting command to the circuit, and the preheat circuit 3 stops preheating while the dimming circuit 4 turns off the circuit SW to light up the discharge lamp. Then the circuit 4 turns on the circuit SW to shortcircuit the two filaments of the discharge lamp 8, and that portion of high frequency current from the inverter 2 which remains after bypassing with a capacitor C flows through the circuit SW. Then this switch SW is put off, and the rated current is sent from the inverter 2 to light up the discharge lamp 8. |
