| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive discharge lamp lighting device, capable of precisely detecting the state of a load, such as a discharge lamp in the end stage of life time or the number of lamps and protecting a circuit. SOLUTION: This lighting device comprises an inverter means 1 for supplying AC power to a discharge lamp LA1 by the oscillating operation of two switching elements Q10 and Q11 connected in series with each other; a load part 6 consisting of a resonance inductor L1 connected to the output of the inverter means 1, a resonance capacitor C1; a DC cut capacitor C2 and the discharge lamp LA1; a load-detecting means 3 for detecting the load state of the discharge lamp LA1 by the end-to-end voltage of the DC cut capacitor C2; a life time judgment means 4 for judging the life time of the discharge lamp LA1, according to the detection result of the load detecting means 3; an oscillation control means 2 for controlling the oscillating operation of the switching elements Q10 and Q11 of the inverter means 1, according to the judgment result of the load judgment means 4; and a control power source part 9 for ensuring the power supply from the DC cut capacitor C2. |
