Metal halide discharge lamps

摘要

In high pressure discharge lamps such as related metal halide lamps (10), in addition to emitting light, mercury is employed as a buffer gas to increase the temperature of the arc tube (1), to promote the evaporation of light-emitting material, and to regulate arc tube (1) pressure. However, mercury itself is damaging to the environment and it has therefore been the desire of manufacturers to develop an arc tube (1) that does not employ mercury. It is the object of the present invention to provide an arc tube (1) with improved chromaticity and start-up characteristics that does not contain mercury, and to provide a vehicle headlamp (11) equipped with a metal halide lamp (10) having this arc tube (1), where both the evaporation of low melting point metal halides is promoted and the start-up characteristics of the arc tube (1) are improved.