US4783613A
Expired / Lapsed
US
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Impregnated cathode
Assignee: Hitachi Ltd
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Filing: 1987-05-28
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Granted: 1988-11-08
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Expires: 2007-05-28
Abstract
Abstract An impregnated cathode comprising a refractory porous body whose pore parts are impregnated with an electron emissive material including barium and a thin film layer comprising tungsten, scandium and/or an oxide of scandium, deposited on the surface of the refractory porous body, characterized in that the thin film layer contains an oxide of tungsten, and/or an oxide of tungsten and scandium, has a distinguished electron emission property and a long life.
Inventors
- 👤 Shigehiko Yamamoto
- 👤 Isato Watanabe
- 👤 Sadanori Taguchi
- 👤 Susumu Sasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:21
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/13; H01J1/20; H01J1/28
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
81 words
An impregnated cathode which comprises a refractory porous body whose pore parts are impregnated with an electron emissive material including barium, and a thin film layer comprising tungsten and at least one member selected from the group consisting of scandium and an oxide of scandium, deposited on the surface of the refractory porous chathode, the thin film layer further containing at least one oxide selected from the group consisting of an oxide of tungsten and an oxide containing tungsten and scandium.
Claim 2
Dependent Claim
81 words
An impregnated cathode which comprises a refractory porous body whose pore parts are impregnated with an electron emissive material including barium, and a thin film layer comprising tungsten and at least one member selected from the group consisting of scandium and an oxide of scandium, deposited on the surface of the refractory porous chathode, the thin film layer further containing at least one oxide selected from the group consisting of an oxide of tungsten and an oxide containing tungsten and scandium.
Claim 3
Dependent Claim
47 words
An impregnated cathode according to claim 1, wherein the at least one oxide is an oxide of tungsten obtained by oxidizing the tungsten in the thin film layer comprising tungsten and at least one member selected from the group consisting of scandium and an oxide of scandium.
Claim 4
Dependent Claim
21 words
An impregnated cathode according to claim 2, wherein the thin film layer has a thickness of 10 nm to 10 μm.
Claim 5
Dependent Claim
19 words
An impregnated cathode according to claim 1, wherein the thin film layer contains an oxide containing tungsten and scandium.
Claim 6
Dependent Claim
31 words
An impregnated cathod according to claim 4, wherein the oxide containing tungsten and scandium is at least one of Sc 2 W 3 O 12 and Sc 6 WO 12 .
Claim 7
Dependent Claim
21 words
An impregnated cathode according to claim 4, wherein the thin film layer has a thickness of 10 nm to 10 μm.
Claim 8
Dependent Claim
33 words
An impregnated cathode according to claim 4, wherein the oxide containing tungsten and scandium is in an amount of 2% to 50% on the basis of the weight of the thin film layer.
Claim 9
Dependent Claim
16 words
An impregnated cathode according to claim 1, ( wherein the thin film layer contains tungsten oxide.
Claim 10
Dependent Claim
14 words
An impregnated cathode according to claim 8, wherein the tungsten oxide is tungsten dioxide.
Claim 11
Dependent Claim
20 words
An impregnated cathode according to claim 8, wherein the thin film layer has a thickness of 50 to 1,000 nm.
Claim 12
Dependent Claim
67 words
An impregnated cathode according to claim 9, wherein the oxide of scandium in the thin film layer is in an amount of 2 to 30% on the basis of the weight of the thin film layer and a total of the oxide of scandium and the tungsten dioxide is in an amount of less than 50% on the basis of the weight of the thin film layer.
Claim 13
Dependent Claim
22 words
An impregnated cathode according to claim 1, wherein said thin film layer is a layer formed by sputtering or chemical vapor deposition.
Claim 14
Dependent Claim
36 words
An impregnated cathode according to claim 1, wherein the thin film layer is a coating layer formed on the surface of the impregnated cathode after impregnation of the electron emissive material in the refractory porous body.
Claim 15
Dependent Claim
48 words
An impregnated cathode according to claim 1, wherein the amount of said at least one member in the thin film layer is 1-30% by weight, and 1-50% by weight of the total tungsten of the thin film layer is in the form of said at least one oxide.
Claim 16
Dependent Claim
31 words
An impregnated cathode according to claim 1, wherein the refractory porous body has incorporated therein an activator selected from the group consisting of Zr, Hf, Ti, Cr, Mn, Si and Al.
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) | 1991-11-08 | 1992-05-09 | 1992-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-11-08 | 1996-05-09 | 1996-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-11-08 | 2000-05-09 | 2000-11-08 | $7700.00 | Window Closed / Lapsed |