| 摘要 |
PURPOSE:To reduce consumed power of a power supply by reducing short circuit current after the lighting operation of a lighting device for a discharge lamp is started. CONSTITUTION:A lighting device for discharge lamp is composed of a stabilized DC power supply 30, an AC converting circuit 31 connected with the output terminal of the DC power supply 30, and a discharge lamp 16 and reactor 15 connected in series between the output terminals of the AC converting circuit 31, and the arrangement further includes a current sensing circuit 24 which is connected with the input terminal of the AC converting circuit 31 and senses the current flowing in the discharge lamp 16 when it is lighted, and an output level changeover circuit 32 which is connected with the output terminal of the DC power supply 30 and drops its output voltage when the current sensing means 24 senses that the current has exceeded a certain specified level. After the lighting operation of the discharge lamp 16 is started, the DC output voltage of the DC power supply 30 drops and the short circuit current of the AC converting circuit 31 is reduced, which accomplishes reduction of the consumed power of the power supply. |
