Patent US3803441A successfully refreshed from Google Patents.
US3803441A
Expired / Lapsed
US
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Indirectly heated type cathode devices using foil heater embedded in mixture of heat resistant dielectric and a metal
Assignee: Toshiba Corp
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Filing: 1973-04-26
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Granted: 1974-04-09
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Expires: 1993-04-26
Abstract
Abstract The cathode device comprises a body consisting of a mixture of electrically insulative and heat resistant substance and a metal and packed in a hollow container, an electron emissive substrate secured to one end of the casing, and a foil heater embedded in the body with its effective surface faced to and spaced from the substrate.
Inventors
- 👤 N Ohsawa
- 👤 K Kobayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 04:32
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13; H01J1/20; H01J1/24
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
36 words
A cathode device according to claim 1 wherein said casing takes the form of a cylinder with both ends opened, and said electron emissive substrate is secured to said cylinder to close one end opening thereof.
Claim 2
Dependent Claim
29 words
A cathode device according to claim 2 wherein the surface of said substrate on the side opposite to said foil heater is reentrant thus forming a partial spherical surface.
Claim 3
Dependent Claim
20 words
A cathode device according to claim 1 wherein said foil heater comprises a thin metal strip shaped into a spiral.
Claim 4
Dependent Claim
30 words
A cathode device according to claim 1 wherein said foil heater comprises a center ring portion and a pair of interleaved spirals with inner ends connected to the ring portion.
Claim 5
Dependent Claim
33 words
A cathode device according to claim 1 wherein said body comprises a mixture of said electrically insulative and heat resistant substance and said metal at a weight ratio of from 95:5 to 70:30.
Claim 6
Dependent Claim
72 words
A cathode device according to claim 1 wherein said electrically insulative and heat resistant substance is a member selected from the group consisting of yttrium oxide, zirconium oxide, aluminium oxide, hafnium oxide, beryllium oxide, magnesium oxide and oxides of rare earth metals and said metal is a member selected from the group consisting of tungsten, nickel, rhenium, tantalum, titanium, zirconium, hafnium, vanadium, neobium, chromium, metals of the platinum group and alloys thereof.
Claim 7
Dependent Claim
29 words
A cathode device according to claim 1 wherein said foil heater comprises an electrical connector connected to one end thereof and a lead wiere electrically connected to said connector.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-08 | 1977-10-08 | 1978-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-08 | 1981-10-08 | 1982-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-08 | 1985-10-08 | 1986-04-09 | $7700.00 | Window Closed / Lapsed |