| 摘要 |
<p>PROBLEM TO BE SOLVED: To eliminate heat conduction to a beads glass at the time of welding and prevent the beads glass from distorting and cracking. SOLUTION: At least one of a pair of main electrodes 3 sealed at the ends of a glass bulb 1 is composed of a rod-shaped metal piece 6 whereto beads glass 4 is attached and a metal cylinder 5 in a cylindrical shape having a bottom, wherein the forefront of the metal piece 6 is abutted to the outer surface of the bottom 5a of the metal cylinder 5, and one welding electrode 7 is inserted through the open end of the cylindrical part 5b of the metal cylinder 5 and abutted to the inner surface of the bottom 5a of the metal cylinder 5 while the other welding electrode 8 is attached to the exposed portion of the metal piece between the beads glass 4 and the bottom 5a of the cylinder 5, and current is fed between the two welding electrodes 7 and 8 so that the outer surface of the bottom 5a of the cylinder 5 is welded to the metal piece 6.</p> |
