| 摘要 |
PROBLEM TO BE SOLVED: To provide an arc tube capable of reducing transparency and suppressing degradation of light flux, without using a shallower recess of a discharge container, or forming a fluorescent layer at the bottom of the recess. SOLUTION: The arc tube 12 uses a discharge container 16 having a recess 14 recessing inwardly in a wall surface. Fluorescent layers 35a, 35b are formed on an inner wall surface of the discharge container 16. The thickness t (μm) of the fluorescent layer 35a in a portion (area A1) in opposition to the bottom 18 of the recess 14 is set to 180/d≤t≤20 (d≥9 mm), where d (mm)is a minimum distance between the bottom 18 of the recess 14 and the portion of the inner wall surface of the discharge container 16, in opposition to the bottom 18. COPYRIGHT: (C)2005,JPO&NCIPI
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