| 摘要 |
PURPOSE:To enhance the reliability of lighting and reduce wasteful power consumption by using a backup power source to maintain feed to a load detecting circuit and a control circuit. CONSTITUTION:Power is fed from a main DC power source E via a power switch SW to a lighting circuit 7 comprising an inverter circuit, a driving circuit for the inverter circuit, and an LC resonance circuit, etc. The circuit 7 feeds power for lighting to a discharge lamp 1 and a detecting circuit 8 for the end of the life of the lamp 1 detects the end of the life of the lamp 1 due to emitter exhaustion and a load detecting circuit 9 detects whether or not the lamp 1 is connected to the circuit 7. A control circuit 10 cuts off or limits feed of power for lighting from the circuit 7 to the lamp 1 in response to the output of a detection signal indicative of the end of the end of the life of the lamp and restores feed of power for lighting in response to the output of a signal indicative of detection of connection after a signal indicative of detection of no load is output. A backup power source BAT continues feed to the circuits 9,10 regardless of whether or not the main DC power supply E from which power is fed to the lighting circuit 7 is cut off. |
