| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp in which cracks (crackings) do not occur at a welding part between a base body part and a cap part constituting an electrode, the electrode is not broken in lighting, a heat transfer body in the electrode is not oxidation deteriorated, a heat transfer effect is exhibited surely, and temperature rise of the tip part of the positive electrode is suppressed surely. SOLUTION: In this discharge lamp, the pair of electrodes 13, 15 are oppositely arranged in a light-emitting tube 11. The electrode 13 is constituted of the base body part 130 and the cap part 131 and includes an annular welding part P welded over the whole circumferential direction while the base body part 130 and the cap part 131 are abutted, the heat transfer body M is sealed into the closed space in the electrode 13, a through-hole 133 for gas introduction is formed at the cap part 131, a fusion sealing part Q is provided at the tip opening of the through-hole 133 for the gas introduction, and the shortest spaced apart distance in the electrode between the welding part P and the fusion sealing part Q is 8 mm or more. COPYRIGHT: (C)2009,JPO&INPIT
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