EP0186348A2
Expired / Lapsed
EP
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Ceramic envelope device for high-pressure discharge lamp
Assignee: NGK Insulators Ltd
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Filing: 1985-12-04
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Granted: —
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Expires: 2005-12-04
Abstract
Abstract A ceramic envelope device for a high-pressure metal-vapor discharge lamp, has a translucent ceramic tube (6), a pair of electrically conducting end caps (14) closing opposite ends of the ceramic tube, and a pair of opposed discharge electrodes (16) each of which is supported at its one end by the corresponding end cap (14) 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 (20). To avoid "arc-back" between the electrode and the end cap and also corrosion of the central portion of the end cap, the electrical insulator has a protruding portion (22) 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 i, radially spaced from the protruding portion of the electrical insulator.
Inventors
- 👤 Hirotsugu Izumiya
- 👤 Takehiro Kajihara
- 👤 Senji Atsumi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 02:02
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/36; H01J61/366
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
151 words
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 an inner surface of the corresponding end cap in a longitudinally inward direction of the ceramic tube, characterized in that: said end caps are covered at their inner surfaces with the corresponding electrically insulating members, at least one of said electrically insulating members having 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, said part of the corresponding electrode being radially spaced a predetermined distance from said at least one of electrically inlsulating members.
Claim 2
Dependent Claim
151 words
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 an inner surface of the corresponding end cap in a longitudinally inward direction of the ceramic tube, characterized in that: said end caps are covered at their inner surfaces with the corresponding electrically insulating members, at least one of said electrically insulating members having 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, said part of the corresponding electrode being radially spaced a predetermined distance from said at least one of electrically inlsulating members.
Claim 3
Dependent Claim
35 words
A ceramic envelope device as claimed in claim 1, wherein said electrically insulating members are made of a refractory ceramic material selected from the group consisting of alumina, beryllia, spinel, boron nitride, and glass frit.
Claim 4
Dependent Claim
21 words
A ceramic envelope device as claimed in claim 2, wherein said electrically insulating members are made of white and opaque alumina.
Claim 5
Dependent Claim
37 words
A ceramic envelope device as claimed in any one of claims 1 to 3 wherein said at least one electrically insulating member has an annular peripheral portion of a constant thickness from which said protruding portion protrudes.
Claim 6
Dependent Claim
31 words
A ceramic envelope device as claimed in claim 4, wherein said annular peripheral portion has a thickness of 0.05-0.8 mm, as measured from the inner surface of the corresponding end cap.
Claim 7
Dependent Claim
46 words
A ceramic envelope device as claimed in any one of claims 1 to 5 wherein said protruding portion is positioned at a radially central part of the corresponding end cap, and is of tubular shape having a central bore through which the corresponding discharge electrode extends.
Claim 8
Dependent Claim
30 words
A ceramic envelope device as claimed in claim 6, wherein said protruding portion has a thickness of 1.0-3 mm, as measured from the inner surface of the corresponding end cap.
Claim 9
Dependent Claim
45 words
A ceramic envelope device as claimed in clair, 6 or claim 7 wherein said protruding portion has a variable-diameter part which has a thickness increasing in a radially inward direction toward said central bore, as measured from the inner surface of the corresponding end cap.
Claim 10
Dependent Claim
69 words
A ceramic envelope device as claimed in any one of claims 6 to 8, wherein said at least one electrically insulating member has a secondary protruding portion which contacts a central part of the corresponding end cap and protrudes from a part of the inner surface of said at least one electrically insulating member into said central bore, said secondary protruding portion being radially spaced from the corresponding electrode.
Claim 11
Dependent Claim
38 words
A ceramic envelope device as claimed in claim 1, wherein said at least one electrically insulating member is of substantially frusto-conical shape having a central bore through which the corresponding discharge electrode extends with a radial gap therebetween.
Claim 12
Dependent Claim
31 words
A ceramic envelope device as claimed in any one of claims 1 to 10 wherein said predetermined distance is not more than a half of a radius of said end caps.
Claim 13
Dependent Claim
20 words
A ceramic envelope device as claimed in claim 11, wherein said predetermined distance is held within the range of 0.1-2mm.
References Cited (Backward Citations)
No citation records indexed.
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