Patent US3631291A successfully refreshed from Google Patents.
US3631291A
Expired / Lapsed
US
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Field emission cathode with metallic boride coating
Assignee: General Electric Co
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Filing: 1969-04-30
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Granted: 1971-12-28
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Expires: 1989-04-30
Abstract
Abstract A field emission cathode comprises a hairpin rhenium filament coated with lanthanum boride and with a fine tungsten tip attached to the rhenium filament serves as an efficient source of electrons. The presence of free lanthanum atoms at the tungsten surface lowers the work function and enhances the field emission from the tungsten tip.
Inventors
- 👤 Louis J Favreau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:49
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/30; H01J1/304
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
17 words
A field emission cathode as recited in claim 1 wherein said sides are made of rhenium metal.
Claim 2
Dependent Claim
25 words
A field emission cathode as recited in claim 2 further comprising support means connected to the ends of said rhenium filament for supporting the same.
Claim 3
Dependent Claim
48 words
A field emission cathode as recited in claim 1 wherein said lanthanum boride coating is applied to each side of said filament for providing a source of free lanthanum atoms which migrate to said tungsten tip at elevated temperatures thereby lowering the work function of said tungsten tip.
Claim 4
Dependent Claim
24 words
A field emission cathode as recited in claim 4 further comprising support means connected to the ends of said filament for supporting the same.
Claim 5
Dependent Claim
48 words
A field emission cathode as recited in claim 2 wherein said lanthanum boride coating is applied to the sides of said filament for providing a source of free lanthanum atoms which migrate to said tungsten tip at elevated temperatures thereby lowering the work function of said tungsten tip.
Claim 6
Dependent Claim
25 words
A field emission cathode as recited in claim 1 further comprising support means connected to the ends of said rhenium filament for supporting the same.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-27 | 1975-06-28 | 1975-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-27 | 1979-06-28 | 1979-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-27 | 1983-06-28 | 1983-12-28 | $7700.00 | Window Closed / Lapsed |