| 摘要 |
<P>PROBLEM TO BE SOLVED: To correctly detect the end stages of lives of a plurality of discharge lamps even when all the discharge lamps are at the end stages of the lives thereof or one of the discharge lamp is at the end stage of the life thereof and the other discharge lamps are not at the end stages of the lives thereof. <P>SOLUTION: When a high-frequency voltage obtained by converting a D.C. voltage by an inverter part 11 is supplied to the discharge lamps 20 and 21 through a resonance circuit part 12, a lamp voltage detection part 4 detects a lamp voltage to output a lamp voltage detection value. A balancer voltage detection part 5 detects a balancer voltage generated in a balancer 13 to output a balancer voltage detection value. Then, a multiplier 60 multiplies the lamp voltage detection value by the balancer voltage detection value by inputting the lamp voltage detection value and the balancer voltage detection value in a control part 6. Thereafter, a comparator 61 compares the multiplication value with a threshold voltage, and an oscillation stop control circuit part 62 outputs a stop signal to a first control circuit part 63 and a second control circuit part 64 when the multiplication value exceeds the threshold value to stop the oscillation of the inverter circuit 11. <P>COPYRIGHT: (C)2007,JPO&INPIT |
