US4117374A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluorescent lamp with opposing inversere cone electrodes
Assignee: General Electric Co
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Filing: 1978-02-28
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Granted: 1978-09-26
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Expires: 1998-02-28
Abstract
Abstract Electrodes for high current electric discharges in low pressure gases comprise a heated filament, coated with emissive material and surrounded by a hollow emitting surface in the shape of a truncated cone. The electric discharge initially starts from a spot on the filament and transfers to a diffuse mode at the small end of the cone structure. High current fluorescent lamps which include the electrodes of the present invention are characterized by rapid transition from the spot mode to the diffuse mode discharge and by low cathode fall voltage.
Inventors
- 👤 Harald L. Witting
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 02:40
CPC Classifications
H; H01; H01J; H01J61/00; H01J61/02; H01J61/04; H01J61/06; H01J61/09
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
98 words
In an electrode structure, which includes an improved cathode for an electric discharge emanating from substantially a single direction, comprising: a refractory metal cylinder, open at both ends and having inner and outer surfaces; and an emissive mix coated filament centrally disposed within said cylinder; the improvement wherein said cylinder comprises a truncated conical structure having a wide end and a narrow end with the narrow end thereof directed toward the electric discharge, whereby a transition, from a termination of the electric discharge on the filament, to a termination of the electric discharge on the cylinder, is hastened.
Claim 2
Dependent Claim
98 words
In an electrode structure, which includes an improved cathode for an electric discharge emanating from substantially a single direction, comprising: a refractory metal cylinder, open at both ends and having inner and outer surfaces; and an emissive mix coated filament centrally disposed within said cylinder; the improvement wherein said cylinder comprises a truncated conical structure having a wide end and a narrow end with the narrow end thereof directed toward the electric discharge, whereby a transition, from a termination of the electric discharge on the filament, to a termination of the electric discharge on the cylinder, is hastened.
Claim 3
Dependent Claim
18 words
The electrode of claim 1 further comprising an electron-emissive material disposed on the inner surfaces of said cylinder.
Claim 4
Dependent Claim
18 words
The structure of claim 1 wherein the apex angle of said conical structure is between 4° and 90°.
Claim 5
Dependent Claim
22 words
The electrode of claim 2 wherein said refractory metal cylinder is selected from the group consisting of molybdenum, nickel, tungsten, and rhenium.
Claim 6
Dependent Claim
22 words
The electrode of claim 2 wherein said cylinder comprises a foil having a thickness between approximately 0.005 mm and approximately 0.05 mm.
Claim 7
Dependent Claim
25 words
The electrode of claim 2 wherein said truncated conical structure has a narrow end with a diameter between approximately 4 mm and approximately 20 mm.
Claim 8
Dependent Claim
25 words
The structure of claim 1 further comprising a disk of metal foil, disposed across and substantially closing off the wide end of said conical structure.
Claim 9
Dependent Claim
106 words
A fluorescent lamp comprising: a substantially tubular, light-transmissive, evacuable envelope having two ends; a fill gas contained within said envelope; at least one electrode structure disposed at each end of said envelope, said electrode structure comprising a truncated conical, refractory metal cylinder open at both ends and having a wide end and a narrow end with the narrow end directed substantially toward the end of said tubular envelope opposite that end in which said electrode structure is disposed, said electrode structure also possessing an emission mix coated filament centrally disposed within said cylinder; and means for establishing and maintaining an electric discharge between said electrode structures.
Claim 10
Dependent Claim
106 words
A fluorescent lamp comprising: a substantially tubular, light-transmissive, evacuable envelope having two ends; a fill gas contained within said envelope; at least one electrode structure disposed at each end of said envelope, said electrode structure comprising a truncated conical, refractory metal cylinder open at both ends and having a wide end and a narrow end with the narrow end directed substantially toward the end of said tubular envelope opposite that end in which said electrode structure is disposed, said electrode structure also possessing an emission mix coated filament centrally disposed within said cylinder; and means for establishing and maintaining an electric discharge between said electrode structures.
Claim 11
Dependent Claim
18 words
The lamp of claim 8 wherein said envelope comprises a glass tube having side walls defining alternating indentations.
Claim 12
Dependent Claim
21 words
The lamp of claim 8 wherein said fill gas comprises, as a major fraction, neon and further comprises saturated mercury vapor.
Claim 13
Dependent Claim
18 words
The lamp of claim 10 wherein the vapor pressure of said neon is less than approximately 3 torr.
Claim 14
Dependent Claim
25 words
The lamp of claim 10 wherein said means for establishing and maintaining said discharge include a high frequency power source connected between said electrode structures.
Claim 15
Dependent Claim
23 words
The lamp of claim 12 wherein said high frequency power source operates at a frequency greater than or equal to approximately 25 kHz.
Claim 16
Dependent Claim
30 words
The lamp of claim 13 wherein said means for establishing and maintaining said discharge further include a preheat starting circuit connected in series with the filament of said electrode structures.
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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) | 1981-09-25 | 1982-03-27 | 1982-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-09-25 | 1986-03-27 | 1986-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-09-25 | 1990-03-27 | 1990-09-26 | $7700.00 | Window Closed / Lapsed |