| 摘要 |
PURPOSE:To improve reliability by carrying out judgment of burnt-out filament in a lamp when the number of times of event that the time from the time point when the A.C. power supply output is stopped instantaneously to the time point of detection operation of output change detection means is in correspondence with the judgment time set at every lighting-up operation is counted over specified times. CONSTITUTION:When a lamp L1 is burnt-out in its filament, output fluctuation of a constant current power supply device 2 is detected by a burnt-out filament generation judgment part 6 and the output is sent to a short circuit release operation count part 10. A secondary side over-voltage of an insulation transformer CT1 is detected by an over-voltage detection part 21 of a terminal part R1 and the detection signal is output to a short-circuit control part 23. Then, the short circuit control part 23 controls a thyrister part 22 to make the secondary side of the transformer CT1 short-circuited. When a power supply control part 8 stops the output of a device 2 instantaneously, a current interruption detection part 25 detects it to output the signal to the control part 23 and release the short circuit CT1 of the transformer at every specified time. After that, a judgment part 6 detects the change in output voltage of the device 2 for judging generation of burnt-out filament and outputting the signal to a count part 10. When the count value is over a specified value, a burnt-out filament position judgment 9 judges generation of burnt-out filament of lamp L1. |
