| 摘要 |
PROBLEM TO BE SOLVED: To provide a lamp lighting device equipped with a current limiting function useful in discriminating abnormalities and load fluctuation or light control of a lamp. SOLUTION: An output voltage of a transformer TR1 is divided and detected by capacitors C1, C2, while an out voltage of a transformer TR2 is divided and detected by capacitors C3, C4, and their voltage differences are detected with a comparator 24. A level decision unit 26 compares the above voltage differences with a given threshold Vref, and outputs an H-level signal into a control circuit 12 when the differences reach the threshold Vref. The control circuit 12 determines, when the H-level signal is input from the level decision unit 26, that a 2kΩshort circuit occurred at either the transformer TR1 or the transformer TR2, and operates switches S1, S2 into a open state to shut out power supply from alternate-current power sources 10-1, 10-2. COPYRIGHT: (C)2006,JPO&NCIPI |
