| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a metal halide lamp that has high luminous efficiency, a little drop in lamp voltage and good color of light by improving balance of filling quantity of a first and a second halides in the mercury-free lamp, and a headlamp for vehicle using the same. <P>SOLUTION: The metal halide lamp comprises an airtight container 1 having fire resistance and light translucency, a pair of electrodes 3, 3 sealed inside it opposed to each other with a distance between electrodes of 5 mm or less, and a discharge medium which contains a first halide made of mainly Sc halide and Na halide, a second halide mainly contributing to forming lamp voltage, and xenon having not less than 5 atmospheric pressure at a temperature of 25°C and is filled in the airtight container, and in which a/(a+b) satisfies the formula 0.25<a/(a+b)<0.5 when the filling quantity of Sc halide is a, the filling quantity of Na halide is b, all expressed in mass, and which does not contain mercury in substance, and is lighted at a lamp power of 60 W or less at a steady state. <P>COPYRIGHT: (C)2004,JPO |
