PROBLEM TO BE SOLVED: To provide a high wattage ceramic metal halide lamp which maintains high luminous efficiency.;SOLUTION: A high wattage ceramic metal halide lamp includes a luminous tube filled with at least mercury and a metal halide. The luminous tube has a thick tube, and a pair of thin tubes formed at both ends thereof. A current introducer is passed through the inside of each thin tube, and the ratio of the external diameter L4 of the current introducer to the internal diameter L6 of the thin tube falls within a range of 0.96≤L14/L6≤0.98. The space between the thin tube and the current introducer is divided into a sealed region and a non-sealed region, and the cavity GA in the non-sealed region is in a range of 5.0 mm3≤GA≤17.5 mm3.;COPYRIGHT: (C)2014,JPO&INPIT
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