| 摘要 |
PURPOSE:To detect the non-lighting when a discharge lamp is started and the half-wave lighting during the stationary lighting as an abnormality. CONSTITUTION:A comparator CP setting the output to the H-level when the tube voltage of a discharge lamp D detected by a tube voltage detecting circuit 4 exceeds the preset threshold value is provided. A timer circuit 5 starting the counting operation after an inverter device 1 is started is provided. The timer circuit 5 counts the period when the discharge lamp D can be lighted. One input of an AND circuit A is made the H-level when the counting operation of the timer circuit 5 is completed, and the output of the comparator CP can be inputted to an inverter controller 2. A fixed delay time is set by a delay circuit 6 after the counting operation of the timer circuit 5 is completed. The threshold value of the comparator CP is set higher for the counting time of the timer 5 and the delay time of the delay circuit 6 than that for the subsequent period. |
