| 摘要 |
PROBLEM TO BE SOLVED: To easily carry out detection of the last stage of lifetime of a discharge lamp 51, and to realize this with a simple circuit constitution. SOLUTION: When a capacitor 11 to constitute a half bridge-shaped inverter circuit is connected to the discharge lamp 51 and a circuit grounding electrical potential, and the discharge lamp 51 is normally discharged, voltage of a direct current power supply 71 is set in order to make voltage which is standardized based on a circuit grounding potential of the capacitor 11 slightly larger than the peak value of a lamp voltage. Furthermore, when a circuit which detects the lamp voltage of the discharge lamp 51 is provided and the peak value of the lamp voltage becomes lower than the circuit grounding potential, the circuit is constituted so as to determine that the discharge lamp 51 is in an abnormal discharge. COPYRIGHT: (C)2006,JPO&NCIPI |
