| 摘要 |
PROBLEM TO BE SOLVED: To provide a protection circuit in which determination precision of lighting status of a lamp is improved by leaps and bounds, and to provide a lamp driving device having the protection circuit. SOLUTION: The protection circuit includes a detection circuit 401 which detects an electric voltage at a neutral point of a transformer circuit 20 which outputs a voltage of reversed phase with identical period to two lamps connected respectively to each terminals on winding start side of two secondary windings and has formed a neutral point by connecting each terminals on winding end side, a comparison circuit 402 which compares the detection voltage with a prescribed reference voltage, and a control circuit 403 which controls switching on and off of the current voltage to be supplied to the transformer circuit 20 based on the comparison result. Thereby, the protection circuit can be constructed which is improved by leaps and bounds in the determination precision of the lighting status of the lamp. COPYRIGHT: (C)2009,JPO&INPIT |
