US3688151A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device having an electric discharge tube comprising a field emission cathode, and discharge tube destined for such a device
Assignee: US Philips Corp
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Filing: 1970-09-14
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Granted: 1972-08-29
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Expires: 1990-09-14
Abstract
Abstract In a cold cathode consisting of a layer of aluminum oxide between a plate and a grid, the aluminum oxide is formed on aluminum as a porous oxide layer. The meshes of the grid are so fine that the grid is attracted against the oxide due to the voltage difference with the plate.
Inventors
- 👤 Constant Gijsbertus Joh Jansen
- 👤 Klaas Compaan
- 👤 Albertus Venema
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:14
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/30; H01J1/304
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
34 words
A device as claimed in claim 1, wherein the potential difference across the aluminum oxide layer is so large that the metal grid is attracted against the aluminum oxide layer by the electrostatic force.
Claim 2
Dependent Claim
21 words
A device as claimed in claim 2, wherein the potential difference across the aluminum oxide layer is more than 50 volts.
Claim 3
Dependent Claim
81 words
An electric discharge tube destined for a device as claimed in claim 1, wherein the porous aluminum oxide layer has a hexagonal structure in which cavities at right angles to the surface alternate with intermediate material, both with transverse dimensions in the order of magnitude of hundreds of AU and the cavities and the intermediate material are separated from the underlying aluminum by a closed layer of aluminum oxide having a thickness in the order of magnitude of hundreds of A-units.
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) | 1975-08-29 | 1976-02-28 | 1976-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-29 | 1980-02-28 | 1980-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-29 | 1984-02-28 | 1984-08-29 | $7700.00 | Window Closed / Lapsed |