| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC-type metal halide lamp usable for general lighting, applicable to all lighting positions, and having a discharge container made of ceramics. SOLUTION: This metal halide lamp has an arc tube 7 filled with mercury, a rare gas, and a halide. The arc tube 7 has a positive electrode and a negative electrode sealed therein, has at least one heat shield (8, 9 of Figure) on the negative-electrode side of the arc tube 7, and is applicable to all lighting positions. The two electrodes sealed in the arc tube 7 are different in shape from each other. The positive electrode is made of tungsten and has a spherical end part, while the negative electrode is made up of a rod made of thorium tungsten and a coil 2 on the rod.
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