DISCHARGE LAMP LIGHTING CIRCUIT FOR VEHICLE

摘要

PURPOSE:To prevent the DC lighting state from being continued by the periodic fluctuation of the power voltage caused by the use of a heavy load (an engine starter or the like) when a discharge lamp is DC-lighted during the prescribed period at the initial stage of the lighting of the discharge lamp. CONSTITUTION:This lighting circuit is provided with a DC/AC converting circuit 7 for converting the DC voltage into the rectangular wave AC voltage and feeding it to a discharge lamp 10 and a DC lighting control circuit 19 prohibiting the polarity inversion of the rectangular wave in the DC/AC converting circuit 7 for a prescribed period after the lighting of the discharge lamp 1 is discriminated by a lighting discriminating circuit 16 discriminating the lighted or unlighted state of the discharge lamp 1 and DC-lighting the discharge lamp 1. When the unlighted state of the discharge lamp 1 is discriminated during the DC lighting period of the discharge lamp 1, the DC lighting control circuit 19 releases the DC lighting of the discharge lamp 1, then the discharge lamp 1 is again DC-lighted after the re-lighting of the discharge lamp 1 is discriminated and the polarity of the rectangular wave is inverted.