Patent ID: 7679290

Claim:
A metal halide lamp comprising an arc tube and a first metal halide that is enclosed in the arc tube, wherein the first metal halide is a halide of at least one metal selected from the group consisting of dysprosium, holmium and thulium, and wherein the arc tube includes: a main tube made of a light-transmitting ceramic; a first thin tube coupled to a first end of the main tube; a second thin tube coupled to a second end of the main tube; and a pair of electrode leads, which are inserted into the first and second thin tubes, respectively, such that the far ends of the leads face each other inside the main tube, and wherein the respective ends of the first and second thin tubes are sealed with a sealing material, and wherein at least a portion of the surface of the sealing material communicates with the inside of the main tube through a gap created between the inner wall of the thin tubes and the surface of the electrode leads, and wherein a second metal halide, which has a lower vapor pressure than that of the first metal halide at a temperature at sealing portions while the lamp is ON, is enclosed in the arc tube, and wherein the second metal halide is a halide of at least one metal selected from the group consisting of calcium, strontium, barium, lanthanum, samarium and europium; wherein the arc tube has portions of which the inside diameter decreases monotonically toward the ends, wherein the sealing portions are made of a material including SiO 2 , and wherein the second metal halide in a liquid phase is present on a surface of the sealing material and the first metal halide is diluted on the surface of the sealing material.