| 摘要 |
PURPOSE:To have optimum preheat characteristic in accordance with the lamp dimmed condition by furnishing a preheat control means, which controls preheating of lamp filament in response to a dim signal. CONSTITUTION:Existing invention includes an inverter 1 operating with a DC power as a power supply, wherein the DC power is obtained by rectifying an AC power supply with a diode bridge DB, and thereby dimming of a lamp l is made with this inverter 1 in accordance with a dim signal given by a dimming level setting part 9. A preheat power supply 11 supplies preheat power to a filament F of the lamp l, and the preheat power supplied to the filament F from this preheat power supply 11 is controlled by a preheat control circuit 10 in conformity to the dim signal at the dimming level setting part 9. This enables proper preheating of the lamp filament F in good accordance with the dimming condition, and this optimum preheating enables smooth dim control. |
