Metal halide lamp, headlight apparatus for vehicle using the same, and method of manufacturing metal halide lamp

摘要

A metal halide lamp comprises a discharge container including a discharge space and a pair of sealing sections. A discharge medium containing a metal halide and a rare gas and essentially free from mercury is sealed in the discharge container. A pair of electrodes are arranged to face each other within the discharge space, and the side edge portions on the side of the proximal end portion of these electrodes are held by the sealing sections. The amount of water contained in the metal halide, i.e., the light-emitting material, included in the metal halide lamp essentially free from mercury, i.e., Hg-less metal halide lamp, is controlled to 50 ppm or less.