| 摘要 |
PROBLEM TO BE SOLVED: To surely judge the life end of a high pressure discharge lamp even in a state of dimming. SOLUTION: The discharge lamp lighting device comprises circuits for lighting the high pressure discharge lamp 7 such as a lighting circuit composed of a rectifier circuit 3, an output control circuit 4, a polarity switching circuit 5, a control part 10; a light dimmer 11 converting a light control signal into a voltage signal, inputting the voltage signal to the control part 10, and controlling the lighting of the high pressure discharge lamp; and a lamp voltage detection circuit 12 detecting the lamp voltage of the high pressure discharge lamp. The control part determines a judging voltage for judging the life end of the high pressure discharge lamp depending on the value of the voltage signal from the light dimmer circuit, and compares the determined judging voltage with the lamp voltage detected by the lamp voltage detection circuit, and judges the life end of the high pressure discharge lamp when the lamp voltage comes up to the judging voltage. COPYRIGHT: (C)2003,JPO |
