| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which reliably detects an abnormal state of a discharge lamp such as the end of its service life or non-lighting, irrespective of the type of the discharge lamp, and stops the oscillating operation of an inverter circuit. <P>SOLUTION: The discharge lamp lighting device comprises discharge lamp load circuits L100, L110 for lighting the discharge lamps 7, 11 with a high frequency current fed from the inverter circuit that converts a direct current from a direct current power supply 1 into the high frequency current. A coupling capacitor 5 connected to an output of the inverter circuit and a series circuit made up of choke coils 6, 10 are connected in this order to a cathode of the direct current power supply 1 via the discharge lamps 7, 11. The discharge lamp lighting device further comprises: a ± voltage detecting circuit D100 for detecting a voltage between the cathode of the direct current power supply 1 and a node between the coupling capacitor 5 and the choke coils 6, 10 through averaging the same; and a holding circuit H100 for stopping the oscillation of the inverter circuit and maintaining the stopped state when the voltage detected by the detecting circuit D100 falls outside a predetermined range of positive/negative voltage. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
