| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of detecting emission-less states on both sides and an emission-less state on one side by a single detection circuit, and to provide an abnormality detection circuit of discharge lamp. SOLUTION: A constant voltage diode 21b clips a positive voltage out of a terminal voltage of a discharge lamp 20 at a predetermined level. A low-pass filter comprising a resistor 24 and a capacitor 26 generates a differential voltage between positive and negative terminal voltages of the discharge lamp 20. A comparison circuit 43 compares the differential voltage with a predetermined threshold value, and outputs the determination result of the emission-less states on both sides or the emission-less state on one side. COPYRIGHT: (C)2007,JPO&INPIT |
