| 摘要 |
PURPOSE:To protect the switching elements of an inverter section by stopping the oscillation of an inverter via the detection of the surge voltage, and performing a restart from the initial state. CONSTITUTION:When surge voltage is detected by voltage dividing resistors 28, 29, an oscillation stopping means stops the action of an inverter 4. The oscillation stopping means is constituted of a transistor 27, a comparator 25, a flip-flop circuit 31, and a drive control circuit 5. When a discharge lamp 8 is lighted after the surge voltage is resolved, the lamp fitting detection signal is artificially inputted to the circuit 5 of the inverter 4 so that a transistor 19 and the flip-flop circuit 31 can be restarted from the initial state. The action of a boost chopper circuit is stopped concurrently with the detection of the surge voltage, the action of the inverter 4 is stopped, no stress is applied to the switching elements 4a, 4b of the inverter 4, and the breakage can be prevented. The elements 4a, 4b are protected, and the life of the discharge lamp 8 can be extended. |
