| 摘要 |
PURPOSE:To prevent a lamp socket from its electric breakdown and an electric shock, when a lamp is replaced, by constituting a circuit so as to interrupt supply of power to the lamp when it is discriminated that the lamp can not be turned on and/or abnormality is generated in a level of battery voltage and polarity. CONSTITUTION:An overvoltage detecting circuit 4, detecting battery voltage for its excessive high level, is connected between input terminals 3, 3' of a lighting circuit 1 connected to positive and negative poles of a battery 2. While providing a lighting switch circuit 5 receiving a signal showing the excessive voltage and a power cutoff signal from a lamp abnormality detecting circuit 13 to interrupt supply of the battery voltage, this circuit 5 is constituted by providing a lighting switch and a power cutoff circuit. The lamp abnormality detecting circuit 13 is constituted so as to output a power cutoff signal by judging a lamp disabled from lighting by the result of measuring non-lighting time of the lamp from the point of time the metal halide lamp 10 is first started by an ignitor starter circuit 11. |
