US4275329A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrode with overwind for miniature metal vapor lamp
Assignee: General Electric Co
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Filing: 1978-12-29
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Granted: 1981-06-23
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Expires: 1998-12-29
Abstract
Abstract An electrode for a miniature high pressure metal vapor lamp comprises a slender tungsten shank joined to a molybdenum inlead by a weld knot. The shank diameter is chosen above the size where melt-back starts at the intended lamp current and is provided wth a fine wire overwind fitting loosely thereon and retained in place by frictional engagement with the weld knot. The overwind reduces breakdown voltage and assures rapid glow-to-arc transition.
Inventors
- 👤 Elmer G. Fridrich
- 👤 John M. Davenport
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:24
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/04; H01J61/06; H01J61/073; H01J61/0732
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
106 words
A high pressure metal vapor lamp arc tube comprising a fused silica envelope containing an ionizable fill including vaporizable metal, self-heating electrodes sealed into opposite ends of said envelope, at least one of said electrodes comprising a tungsten shank exceeding the wire size at which melt-back occurs at the current level in said lamp, said shank being supported by a molybdenum inlead sealed into the envelope and having a weld knot to which said shank is joined and an open overwind of fine wire fitting loosely on said shank and retained in place by frictional engagement with the enlargement in the inlead at the weld knot.
Claim 2
Dependent Claim
106 words
A high pressure metal vapor lamp arc tube comprising a fused silica envelope containing an ionizable fill including vaporizable metal, self-heating electrodes sealed into opposite ends of said envelope, at least one of said electrodes comprising a tungsten shank exceeding the wire size at which melt-back occurs at the current level in said lamp, said shank being supported by a molybdenum inlead sealed into the envelope and having a weld knot to which said shank is joined and an open overwind of fine wire fitting loosely on said shank and retained in place by frictional engagement with the enlargement in the inlead at the weld knot.
Claim 3
Dependent Claim
34 words
A lamp as in claim 1 wherein the portion of the overwind overlapping the weld knot in the direction of the seal is at least partly embedded in the fused silica of the envelope.
Claim 4
Dependent Claim
18 words
A lamp as in claim 1 wherein said one electrode has a ball-like enlargement at the distal end.
Claim 5
Dependent Claim
18 words
A lamp as in claim 1 for a.c. operation wherein both electrodes are constructed like said one electrode.
Claim 6
Dependent Claim
13 words
A lamp as in claim 1 containing mercury and metal halides including thorium.
Claim 7
Dependent Claim
15 words
A lamp as in claim 1 containing mercury, sodium iodide, scandium iodide and thorium iodide.
Claim 8
Dependent Claim
38 words
A miniature lamp as in claim 6 for operation at a current of less than 500 milliamperes wherein the electrode shank is tungsten wire of approximately 7 mils and the overwind is tungsten wire of approximately 2.5 mils.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-06-22 | 1984-12-22 | 1985-06-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-22 | 1988-12-22 | 1989-06-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-22 | 1992-12-22 | 1993-06-23 | $7700.00 | Window Closed / Lapsed |