| 摘要 |
PROBLEM TO BE SOLVED: To provide a discharge lamp capable of preventing degradation of illuminance maintenance. SOLUTION: A globe part 22 is formed in an intermediate part in the lengthwise direction of an arc tube 21. A discharge space 23 is formed in the globe part 22. In the discharge space 23, mercury having a purity of 99.999-99.999999 %, and a rare gas such as Br gas and Ar gas of halogen elements as filler chemicals are enclosed. The total amount of Ag and Cu present in mercury as impurities is 0.001-1 ppm. Since blackening can be prevented while optimizing a halogen cycle without unnecessarily increasing the cost, the illumination can be maintained even after long-term usage. COPYRIGHT: (C)2004,JPO
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