| 摘要 |
PROBLEM TO BE SOLVED: To simplify a structure as a whole while downsizing the structure, since a discharge lamp is put out by detecting abnormality of the discharge lamp without providing a special circuit. SOLUTION: A lamp current is detected by a lamp characteristics detecting means with lighting of the discharge lamp controlled by operating an inverter circuit. The detected value of the lamp current is taken in, and the lighting frequency of the inverter circuit is controlled so that lamp power becomes constant in accordance with the detected value, and whether the lighting frequency is out of a prescribed range is determined. If it is determined that the lighting frequency is out of the prescribed range, abnormality is determined, the operation of the inverter circuit is stopped, and the discharge lamp is put out. COPYRIGHT: (C)2006,JPO&NCIPI |
