| 摘要 |
Even if a DC output voltage of a step-down chopper circuit ( 3 ) is lowered from a value in a non-lighted state or a no-load state due to a discharge occurring between conductors ( 105 a) in a cable ( 104 ), the turn on detection circuit ( 26 a) can discriminates between lighted and non-lighted states without erroneously determining such a discharge as a discharge in a discharge lamp ( 4 ). This allows an operation of the timer ( 29 ) to be continued, so that high-voltage pulses are intermittently applied to prevent continuous discharge between the conductors ( 105 ) and abnormal heat generation in the cable ( 104 ). Further, even if a discharge occurs in an outer tube of the discharge lamp ( 4 ), the turn on detection circuit ( 26 a) never erroneously discriminates this discharge as the lighted state. Thus, the lighting device of the present invention can suppress abnormal heat generations in the components and a socket ( 102 ).
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