| 摘要 |
PURPOSE:To reliably prevent the breakage of the emission tube by installing a first use operating during starting of a high pressure metal vapor electric-discharge lamp and a second fuse operating during stable lighting of the lamp and using a thermoresponsive switch to adaptively operate said fused according to the stage. CONSTITUTION:When an excessive current flows in the feed circuit of an emission tube 1 due to the insulation deterioration of the stabilizer, the first fuse 8 is fused and broken before the breakage of the emission tube 1 since the contact of a thermoresponsive switch 12 is closed during starting ot the lamp. When an excessive current flows during stable lighting of the lamp, an excessive current flows in a second fuse 9 with a small diameter since the contact of the thermoresponsive switch 12 is opened due to heat from the emission tube 1, thereby resulting in fusion of the second fuse 9 before the breakage of the emission tube 1. Therefore, even when an excessive current flows during starting and stable lighting of the lamp, the breakage of the emission tube 1 can be completely prevented. |
