US4736135A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electron emission device provided with a reservoir containing material reducing the electron work function
Assignee: US Philips Corp
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Filing: 1986-06-18
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Granted: 1988-04-05
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Expires: 2006-06-18
Abstract
Abstract In order to improve the stability of a cold cathode (5) of the reverse biased junction type, a vacuum space (2) is coupled with a reservoir (10), within which a source (21) of material reducing the work function, for example caesium, is present. By influencing the vapor pressure and the temperature in component parts (13, 16) of the reservoir (10) and in the source (21), loss of caesium due to adsorption or other phenomena occurring at the emitting surface (8) of the cathode (5) can be compensated for by an incident flow of caesium (25).
Inventors
- 👤 Jan Zwier
- 👤 Johannes H. A. Vasterink
- 👤 Johannes van Esdonk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:48
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13; H01J1/20; H01J1/28; H01J1/32; H01J1/30; H01J1/308; H01J1/34; H01J3/00; H01J3/02; H01J2201/00; H01J2201/34; H01J2201/342; H01J2201/3421; H01J2201/3423
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
124 words
An electron discharge tube comprising a sealed envelope containing a cathode having an electron-emitting surface coated with a work-function-reducing material, said envelope further containing means for providing to said electron-emitting surface a regulated supply of the work-function-reducing material to compensate for a loss of said material during operation of the tube, said means including: (a) a reservoir having an exit opening with predetermined dimensions in communication with a predefined space in which the cathode is located; and (b) a source contained in the reservoir for supplying the material to the reservoir at a rate sufficient to establish therein a predetermined vapor pressure; said predetermined vapor pressure and said predetermined dimensions collectively establishing a predetermined rate of flow of said material to the electron-emitting surface.
Claim 2
Dependent Claim
124 words
An electron discharge tube comprising a sealed envelope containing a cathode having an electron-emitting surface coated with a work-function-reducing material, said envelope further containing means for providing to said electron-emitting surface a regulated supply of the work-function-reducing material to compensate for a loss of said material during operation of the tube, said means including: (a) a reservoir having an exit opening with predetermined dimensions in communication with a predefined space in which the cathode is located; and (b) a source contained in the reservoir for supplying the material to the reservoir at a rate sufficient to establish therein a predetermined vapor pressure; said predetermined vapor pressure and said predetermined dimensions collectively establishing a predetermined rate of flow of said material to the electron-emitting surface.
Claim 3
Dependent Claim
135 words
An electron discharge tube comprising a sealed envelope containing a cathode having an electron-emitting surface coated with a work-function-reducing material, said envelope further containing means for providing to said electron-emitting surface a regulated supply of the work-function-reducing material to compensate for a loss of said material during operation of the tube, said means including a reservoir comprising first and second compartments communicating through a passageway with predetermined dimensions, said first compartment containing a source for supplying the material to the reservoir at a rate sufficient to establish a predetermined vapor pressure, and said second compartment having an exit opening with predetermined dimensions communicating with a predefined space in which the cathode is located, said predetermined vapor pressure and said predetermined dimensions collectively establishing a predetermined rate of flow of said material to the electron-emitting surface.
Claim 4
Dependent Claim
135 words
An electron discharge tube comprising a sealed envelope containing a cathode having an electron-emitting surface coated with a work-function-reducing material, said envelope further containing means for providing to said electron-emitting surface a regulated supply of the work-function-reducing material to compensate for a loss of said material during operation of the tube, said means including a reservoir comprising first and second compartments communicating through a passageway with predetermined dimensions, said first compartment containing a source for supplying the material to the reservoir at a rate sufficient to establish a predetermined vapor pressure, and said second compartment having an exit opening with predetermined dimensions communicating with a predefined space in which the cathode is located, said predetermined vapor pressure and said predetermined dimensions collectively establishing a predetermined rate of flow of said material to the electron-emitting surface.
Claim 5
Dependent Claim
30 words
An electron discharge tube as in claim 1 or 2 where the cathode is secured to an outer surface of the reservoir in a location adjacent to the exit opening.
Claim 6
Dependent Claim
24 words
An electron discharge tube as in claim 1 or 2 including means for regulating the temperature in the reservoir, thereby regulating said vapor pressure.
Claim 7
Dependent Claim
35 words
An electron discharge tube as in claim 1 or 2 where the space in which the cathode is located is contained within a grid having an opening through which electrons produced by the cathode pass.
Claim 8
Dependent Claim
38 words
An electron discharge tube as in claim 5 where at least one of: (a) an outer surface of the reservoir adjacent the exit opening, or (b) an inner surface of the grid, has applied thereto a gettering material.
Claim 9
Dependent Claim
29 words
An electron discharge tube as in claim 6 where the gettering material comprises at least one of the materials selected from the group consisting of gold, antimony and silver.
Claim 10
Dependent Claim
18 words
An electron discharge tube as in claim 1 or 2 where the work-function-reducing material consists essentially of cesium.
References Cited (Backward Citations)
GB817600A
Cited
US3913999A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-04-05 | 1991-10-05 | 1992-04-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-05 | 1995-10-05 | 1996-04-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-05 | 1999-10-05 | 2000-04-05 | $7700.00 | Window Closed / Lapsed |