| 摘要 |
PURPOSE:To stabilize the life performance characteristics of a lamp by forming an electrode provided in a light emitting tube with an electrode rod, an inner coil wound around side electrode rod and besides with electron emissive material stuck thereon, and a metal cylinder surrounding said inner coil. CONSTITUTION:A high pressure sodium lamp is formed by putting electrodes 6 and 7 and a light emitting tube 2 with sodium, mercury and xenon gas sealed therein in an envelope 1. At this time, the electrodes 6 and 7 are composed of an electrode rod 8 made of tungsten of 0.7mm. diameter, an inner coil 9 which is made of a double coil having a tungsten core wire of 250mu diameter wound with a tungsten wire of 32mu diameter and besides electron emissive material 10 is stuck onto, and a metal cylinder 11 made from tantalum surrounding said inner coil. Besides, the metal rod 8 is formed, being protruded from the metal cylinder 11. Therefore, it is possible to suppress the evaporation and sputtering of the electrode material and prevent movement of the brilliant spot of the discharge and improve the life performance characteristics. |
