PURPOSE: To improve the color rendering characteristic without degrading the life property, in a simple structure by supporting an arc tube bulb with a holder member made of a material of low heat conductivity.
CONSTITUTION: An arc tube 1 is stored in an outer tube bulb 3, the inside of which is maintained at high vacuum condition, and on one end of which a base 4 is mounted. The arc tube 1 is sealed airtight in a black substance consisting of alumina ceramic disc having exhausting tubes 13a, 13b on which electrodes 12a, 12b are mounted, on both ends of an arc tube bulb 11 consisting of translucent ceramic (alumina ceramic, for example,) through a glass solder. After the inside of the bulb 11 is exhausted, an emission metal consisting of amalgam of Na and mercury, and a noble gas are sealed, and the outer ends of the tubes 13a, 13b are crashed and are closed airtight. In the arc tube 1, the end surface part, or the exhausting tubes 13a, 13b are supported with support members 53a, 53b through a ceramic holder member 6 of low thermal conductivity.
ITO AKIRA
UCHIDA KAZUO
