| 摘要 |
PURPOSE: To enhance sealability and prolong the lifetime of a lamp by forming leading wires of several pieces of wires or pins, which are made of metal having a heat expansion coefficient considerably smaller than those of sealing devices made of specific ceramic and have a diameter smaller than a specific value. CONSTITUTION: A conductive leading wire 9a of a discharge tube 4 is formed of two or more molybdenum wires each having a diameter of not more than 250μm, and is tightly closed by a ceramics end plug 10a. In contrast, another leading wire 9b is formed of a molybdenum pin, and is tightly closed by an end plug 10b in a similar manner. The end plugs 10a, 10b are made of Al2 O3 , Y2 O3 , MgAl2 O3 or a mixture their. The leading wires 9a, 9b are directly sintered or glass-brazed inside the plugs 10a, 10b, respectively. The leading wires 9a, 9b are made of tungsten, molybdenum or the like having a heat expansion coefficient considerably smaller than those of the ends 10a, 10b. Consequently, a lamp having a relatively small heat expansion coefficient, excellent corrosion resistance and a long lifetime can be provided. |
