METAL HALIDE LAMP AND LIGHTING SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a metal halide lamp having a constant luminescent color with no relation to time elapsed, and an airtight container difficult to be cracked even by excitation of a heavy current and also even by the difference in a coefficient of thermal expansion between an electrode as well as an external conductor and the airtight container. SOLUTION: Mercury is not filled in an airtight container 11. A heat insulating film is formed on the sealing part 13 of the airtight container 11 only on the side of a cathode 15 among a pair of electrodes 14, 15. The sealing part 13 of the airtight container 11 is formed by an inclined function material in which existing proportion of a first and second materials having different physical properties differs depending on a location. A recessed and projecting part having a depth of 0.020-0.070 micron is formed on the surfaces of at least the electrodes 14, 15 among the electrodes 14, 15 and an external conductor 17.