| 摘要 |
A discharge lamp lighting device is provided to comprise tube current detecting circuits 51 to 5n for outputting detection signals VI1 to VIn of tube currents I1 to In flowing through each discharge lamp 11 to 1n from an inverter 3 connected to DC power source 2 via a plurality of transformers 41 to 4n, a maximum detector 6 for detecting a maximum value VIMX of detected signals VI1 to VIn from current detector 51 to 5n, a minimum detector 7 for detecting a minimum value VIMN of detected signals VI1 to VIn from current detector 51 to 5n, a comparison circuit 8 for computing one or plural values of sum, difference, product and quotient between maximum value VIMX from maximum detector 6 and minimum value VIMN from minimum detector 7 to generate a cease signal VCP when the computed value exceeds a given value, and a control circuit 9 for halting operation of inverter 3 when comparison circuit 8 generates cease signal VCP. The device can reliably detect arc discharge resulted from electric connection failure in discharge lamp or lamps by the computed values from comparison circuit 8 to positively protect discharge lamps from overheating by arc discharge at a bad connection location.
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