| 摘要 |
PURPOSE:To prolong the service life of a preheating electrode performing its preheating start only in time of restarting, by installing a glow switch starter in parallel with a luminous tube via the preheating electrode, and also installing a normally closed type thermal responding element in parallel with the preheating electrode. CONSTITUTION:A tungsten filament 14, or a preheating electrode is installed in a spot in close vicinity to a main electrode 2a of a luminous tube 1, and one end of the filament 4 is connected to the electrode 2a while the other end to a glow switch starter 16 respectively, and a normally closed type responding element 15 is connected to the filament 14 in parallel and connected to the starter 16 in series whereby a high pressure mercury vapor lamp is made up after being connected to a base 8 via a ballast 17. And, when this lamp is once turned out and restarts glowing, the thermal responding element 15 is set down to a state of opening circuit and under this condition, the filament 14 is preheated and discharged. Therefore, in time of starting at normal temperature, it will not be preheated but preheated only in time of restarting so that instantaneous restarting is now possible and the filament's service life can be thus prolonged. |
