| 摘要 |
PURPOSE:To obtain a light source with a long life and high illuminance by making the inner diameter of the discharge section of a bulb smaller than that of electrodes and mercury reservoirs of the bulb. CONSTITUTION:The inner diameter of the center discharge section 32 of a bulb 31 is formed smaller than that of the electrode seals and mercury reservoirs 33 at both sides. A thin metal plate 35 with the same thermal expansion coefficient as that of the bulb 31, e.g., Kovar, is welded to the tip of an electrode 34 made of tungsten and is sealed at predetermined both sides of the bulb 31 respectively. Mercury grains 36 and a slight quantity of argon are sealed in the bulb, and the electrode sections are fixed by inserting by pressure external electrode terminals 37. In such a high pressure mercury lamp, the illuminance is improved and the fluorescent surface can be efficiently exposed because the inner diameter of the bulb discharge section is small. In addition, heat radiation due to the thermal conductivity during its operation is sufficiently cooled by outer terminals, thereby the temperature rise of the discharge section is suppressed and the life of the light source can be extended. |
