| 摘要 |
PROBLEM TO BE SOLVED: To prevent cracking on a capillary shaped projecting part for repetition of turning on/off a lamp, when a ceramic arc tube provided with capillary shaped projecting parts sealing a current introducing body at both the ends is provided. SOLUTION: At both the ends of a discharge container 1, ceramic projecting parts 2 of outside diameters smaller than that of a discharge container 1 are provided. At the inside of the projecting parts 2, a thin molybdenum tube 3 formed by welding and connecting an end part of an electrode mandrel 5 with a tip end closing part 3a is inserted and arranged via a fine gap. By sealing an inner wall surface of the ceramic projecting part 2 and an outer peripheral surface of the molybdenum tube 3 by a frit layer 8, a ceramic arc tube is constituted.
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