| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-pressure sodium lamp capable of improving a color rendering property despite an unsaturated figure. SOLUTION: In an arc tube 1, 0.14mg powder 8 formed by mixing cesium chromate (Cs2 CrO4 ) and getter containing 84wt.% zirconium(Zr) and 16wt.% aluminium(Al) at a weight ratio of 1:476.7, 0.5mg sodium and 4.2×10<4> Pa xenon gas are sealed. During lighting a lamp, 0.00017mg cesium is given from the mixed powder 8, and its value is in an unsaturated condition. The arc tube 1 is stored in an 50mm-diameter outer tube 9 formed of hard glass, which is evacuated into a high vacuum with barium getter 10.
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