Patent US4031425A successfully refreshed from Google Patents.
US4031425A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dispenser cathode for a grid-controlled electron tube and method of manufacturing same
Assignee: US Philips Corp
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Filing: 1975-10-02
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Granted: 1977-06-21
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Expires: 1995-10-02
Abstract
Abstract A dispenser cathode for a grid-controlled electron tube in which the emission of surface regions immediately opposite the control grid is reduced by providing projections above the emissive surface of fused, pore-closing portons which have a focussing effect. These projections may be formed by electron beam or laser beam welding.
Inventors
- 👤 Reinhard Ziegler
- 👤 Horst Seifert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 08:40
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13; H01J1/20; H01J1/28; H01J9/00; H01J9/02; H01J9/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
50 words
A sintered dispenser cathode for a grid-controlled electron tube in which the emission of regions of the emissive surface of the cathode immediately opposite to the control grid is reduced, said cathode having projections above the emissive surface of fused pore-closed portions of reduced emission which have a focusing effect.
Claim 2
Dependent Claim
50 words
A sintered dispenser cathode for a grid-controlled electron tube in which the emission of regions of the emissive surface of the cathode immediately opposite to the control grid is reduced, said cathode having projections above the emissive surface of fused pore-closed portions of reduced emission which have a focusing effect.
Claim 3
Dependent Claim
18 words
A sintered dispenser cathode as claimed in claim 1, wherein the dispenser cathode has a concave emissive surface.
Claim 4
Dependent Claim
47 words
In the method of manufacturing a dispenser cathode for a grid-controlled electron tube in which the emission of surface regions of the emissive surface immediately opposite the grid is reduced, the improvement wherein surface regions of the cathode are fused to close pores and form non-emissive projections.
Claim 5
Dependent Claim
47 words
In the method of manufacturing a dispenser cathode for a grid-controlled electron tube in which the emission of surface regions of the emissive surface immediately opposite the grid is reduced, the improvement wherein surface regions of the cathode are fused to close pores and form non-emissive projections.
Claim 6
Dependent Claim
23 words
A method as claimed in claim 3, wherein the fusion is carried out by means of an electron beam or a laser beam.
Claim 7
Dependent Claim
48 words
A method of manufacturing a dispenser cathode as claimed in claim 3, wherein after the projections of reduced emission are formed, the surface regions of the emissive surface of the cathode between the projections are deepened by a material-removing process and the projecting surface regions are thereafter passivated.
Claim 8
Dependent Claim
22 words
A method as claimed in claim 5, wherein the material of the surface regions between the projections is removed by spark erosion.
Claim 9
Dependent Claim
25 words
A method of manufacturing a dispenser cathode as claimed in claim 3, wherein the cathode body is formed with projecting surface regions which are passivated.
Claim 10
Dependent Claim
32 words
A method as claimed in claim 7, wherein the projecting surface regions of the projections are passivated by fusion by means of an electron beam, an ion beam or a laser beam.
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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) | 1980-06-20 | 1980-12-20 | 1981-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-20 | 1984-12-20 | 1985-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-20 | 1988-12-20 | 1989-06-21 | $7700.00 | Window Closed / Lapsed |