Abstract: A ceramic envelope device for an HID lamp, wherein a translucent ceramic arc tube is closed at opposite end sections thereof by respective end caps which support respective discharge electrodes on their inner surfaces. At least one of the opposite end sections of the arc tube is sealed with a sealing layer, and each of the sealed end section of the tube includes a first axial portion having a first inside diameter, and a second axial portion having a second inside diameter smaller than the first inside diameter and disposed axially inwardly of the first axial portion. The first and second axial portions define an annular shoulder surface radially inwardly extending between the first and second inside diameters. The first axial portion preferably has a cylindrical wall thickness of 1.0-1.5 mm, and the annular shoulder surface preferably has a radial width of 0.2-0.8 mm. The sealing layer is interposed between the first axial portion of the arc tube and the corresponding end cap.

Abstract: A ceramic envelope device for a high-pressure metal-vapor discharge lamp, including a translucent ceramic arc tube, a pair of electrically conducting cermet end caps closing opposite open ends of the ceramic arc tube, and having opposite inner surfaces facing each other, the end caps having a pair of inner holes formed in the opposite inner surfaces of the end caps, respectively, and a pair of discharge electrodes each provided in the form of a rod, having first ends supported in the inner holes in the end caps, respectively, and second ends which protrude from the opposite inner surfaces toward each other in a longitudinally inward direction in the ceramic arc tube.

Abstract: A ceramic envelope device for use in a HID (high intensity discharge) lamp, which includes: (a) a translucent ceramic tube; (b) a pair of electrically conductive end caps which close longitudinally opposite ends of the ceramic tube; (c) a pair of oppositely located discharge electrodes each of which is supported at a first end thereof by a corresponding one of the end caps such that a second end of each electrode protrudes from an inner surface of the corresponding end cap in a longitudinally inward direction in the ceramic tube; (d) an electrical insulator provided for one or both of the pair of end caps; and (e) a sealing member disposed to maintain fluid-tightness between an engaging portion of the end cap for which the electrical insulator is provided, and the corresponding end of the ceramic tube.

Abstract: A discharge tube for a high pressure metal vapor discharge lamp is disclosed, which comprises a translucent alumina tubular body, first and second end plates of cermet having a firing shrinkage factor which is less than that of the translucent alumina tubular body, end first and second electrode support members partially embedded in inner sides of the first and second end plates, respectively. The first end plate is fitted to the first end portion of the alumina tubular body and bonded thereto through shrinkage fitting at a shrinkage fitting ratio of the tubular body to the first end plate being from 3 to 6% during a simultaneous sintering of the first end plate to the tubular body and a simultaneous bonding of the first electrode support member to the first end plate through shrinkage fitting at a shrinkage fitting ratio of the first end plate to the first electrode support member being from 4 to 16% when the alumina tubular body is fired to be translucent.

Abstract: A ceramic envelope device for a high-pressure metal-vapor discharge lamp, including a translucent ceramic tube, a pair of electrically conducting end caps closing opposite open ends of the ceramic tube, a pair of oppositely located discharge electrodes each of which is supported at one end thereof by an inner hole in the corresponding end cap, and a pair of power-supply lead members each of which is supported at one end thereof by an outer hole in the corresponding end cap. A space or radial gap is formed between at least a portion of an outer surface of the electrodes and lead members and their respective supporting holes. At least one of the electrodes and the lead members is formed from a twisted wire consisting of a plurality of metallic strands. The electric resistance of each end cap may fall within a range of 0.1-5 .OMEGA..

Abstract: A ceramic envelope device for a high-pressure metal-vapor discharge lamp, including a translucent ceramic tube, a pair of electrically conducting end caps closing opposite ends of the ceramic tube, and a pair of opposed discharge electrodes each of which is supported at its one end by the corresponding end cap such that the other end of the electrode protrudes from the inner surface of the corresponding end cap in a longitudinally inward direction of the ceramic tube. Each of the end caps is covered at its inner surface with an electrical insulator. The electrical insulator has a protruding portion surrounding a part of the corresponding electrode which protrudes from a radially central portion of the inner surface of the corresponding end cap. The surrounded part of the corresponding electrode is radially spaced from the protruding portion (the electrical insulator).

Abstract: Disclosed herein is a discharge tube for a high pressure metal vapor discharge lamp, which discharge tube comprises a translucent alumina tubular body, a lower end plate bonded to one end portion of the alumina tubular body which has an electrode support member inside thereof and is bonded to the alumina tubular body when the alumina tubular body is subjected to the light transmission treatment through firing, another end plate which has an electrode support member inside thereof and is bonded to the other end of the translucent alumina tubular body by means of a frit.

Abstract: A ceramic envelope device for a high-pressure metal-vapor discharge lamp, including a translucent ceramic tube, a pair of end caps closing opposite ends of the ceramic tube, and a pair of oppositely located discharge electrodes each of which is supported at a first end by the corresponding end cap such that a second end of the electrode protrudes from an inner surface of the corresponding end cap in the longitudinal direction of the ceramic tube. The end caps are electrically conductive, and completely covered at their inner surfaces with an electrical insulator.