| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a metal halide lamp suitable for a headlight for an automobile, and composed by considering environment without essentially using mercury, and by restraining occurrence of fluctuation of brightness caused by thinning of an arc; and to provide a headlight device for an automobile using it. <P>SOLUTION: This metal halide lamp HPDL is provided with: a discharge vessel IT equipped with an airtight vessel 1a having an inside volume below 0.1 cc, and a pair of electrodes 1b with an inter-electrode distance set below 5 mm; a discharge medium containing at least two kinds selected from halides of a group comprising sodium Na, scandium Sc, indium In and zinc Zn, containing 2.0-36.0 mg/cm<SP>2</SP>of a metal halide with respect to the inside volume of the airtight vessel 1a and a rare gas, and enclosed in the airtight vessel 1a without essentially containing mercury; and an outer tube OT. The tube wall load in stably lighting it is 60 W/cm<SP>2</SP>or more, and the surface temperature of the lower part center of the airtight vessel 1a in horizontally lighting it is 530±30°C. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
