| 摘要 |
<p>PURPOSE:To reduce the damage and abrasion of an electric discharge lamp bulb by controlling an electric current fed to an electric discharge lamp to be small at the time of a illuminance condition around a vehicle being gradually lowered and large at the rapidly lowered time. CONSTITUTION:A voltage signal corresponding to the illuminance L1. around a vehicle is inputted as output voltage V into comparators 2-4 from an illumination sensor 1. The respective comparators 2-4 compare this output voltage V with the threshold value of the respectively provided illuminance L2-L4. In this case, L2 corresponds to the illuminance enough to light a side lamp, L3 corresponds to the gradually lowered illuminance as at the sunset time, L4 corresponds to the rapidly lowered illuminance, and a signal from the comparator, corresponding to the detected illuminance, among the comparators 2-4 is sent to a control circuit 5. The control circuit 5 outputs corresponding command signals D1-D3, and a driving circuit 19 follows the command signals D1-D3 and feeds a small current to an electric discharge lamp bulb 10 in the case of the commands D1, D2 and a large current in the case of the command D3.</p> |
