Iwasaki Electric Co., Ltd.

Akira Urushihara

Kazushi Tominaga

Shinya Suzuki

Kyoichi Maseki

Masao Niijima

Kazutoshi Kurosawa

A metal halide lamp of the present invention comprises a luminous tube alone without any outer bulb, the luminous tube containing metal halides such as neodymium halides (NdX.sub.3), dysprosium halides (DyX.sub.3) and cesium halides (CsX) in a total amount by mole of 1.times.10.sup.-6 to 8.times.10.sup.-6 mol/cc and the following molar ratios: ##EQU1## as well as rare gas serving as starting auxiliary gas and mercury serving as buffer gas. This structure permits a predetermined vapor pressure of the metal halides sealed in the luminous tube to be obtained without increasing the wall load, as well as the formation of a metal halide lamp having a long life and good color characteristics.

Metal halide discharge lamp

A metal halide lamp apparatus includes a reflecting mirror and a metal halide lamp has a reflecting/thermal insulating film and a frost portion which is partially formed on the lamp outer surface within a predetermined range continued from the reflecting/thermal insulating film. This causes a decrease in an overall illuminance decrease and the attainment of a desired illuminance ratio and prevents the occurrence of irregularity in illuminance and color. In addition, since electrodes are asymmetrically disposed, it is possible to decrease the rate of devitrification of the luminous tube and make an attempt to increase the life of the luminous tube.

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Fukaya, Japan

Akira Urushihara