| 摘要 |
PROBLEM TO BE SOLVED: To provide a metal halide lamp having a high discharge stability in addition to high luminous efficiency in the visible region and suitable light color, and more particularly, having a useful dimmer function. SOLUTION: A discharge space 2 inside a luminous tube 1 of a metal halide lamp is provided with a pair of opposedly protruding electrode 3. In this metal halide lamp not containing mercury, the discharge space 2 is filled with a buffer gas of xenon under the pressure of 7 to 20 atmospheres at room temperature and serving also as a starting gas, and contains one or more kinds of metal halides. The luminous tube 1 has a region of current-volt characteristic which gives a positive resistance coefficient against variations in an input power, and it is driven in that region at a power lower than the rated power in a steady state.
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