| 摘要 |
PURPOSE:To improve the noise performance, and to reduce the number of wiring by detecting the lamp voltage at the time of opening or closing a switch when a discharge lamp is installed in a lamp socket, and resetting or stopping a high voltage generating circuit. CONSTITUTION:A switch 2a is opened when a high pressure discharge lamp 3 is installed in a lamp socket 2, and closed when the lamp 3 is disconnected. A current limiting element 1a for maintaining the lighting condition of the lamp 3 is connected to a power source Vs through a switch SW, and a high voltage pulse generating device 1b is connected to the output end thereof. Then, the high voltage generating device 1b applies the starting pulse to the socket 2, in which the lamp 3 is installed. A pulse stopping circuit 1c detects the voltage of the input end of the socket 2 under the condition that the switch 2a is closed, and after a certain time is passed, the pulse stopping circuit 1c stops the generating device 1b. Since a circuit 1d for resetting the pulse stopping circuit 1c is provided, lamp wires 4a, 4b can be commonly used for the circuit 1d, and the number of feeder lines from the socket 2 can be reduced to two. |
