Patent US3729575A successfully refreshed from Google Patents.
US3729575A
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US
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High voltage insulator having a thick film resistive coating
Assignee: Northrop Grumman Guidance and Electronics Co Inc
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Filing: 1971-10-28
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Granted: 1973-04-24
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Expires: 1991-10-28
Abstract
Abstract A hollow cylindrical electrical high voltage insulator, suitably an aluminum oxide ceramic material, adapted for use in an electron discharge device includes a fused thick film resistive coating on its inner surface that is on the order of 0.002-inch in thickness and which has a resistivity in the range of 3 X 108 to 1013 ohms per square at an ambient temperature of 75*F. In one embodiment the thick film resistive coating is a vanadiumpentoxide chrome-sesquioxide mixture. The coating permits dissipation of surface charges and prevents high energy electrons from penetrating through to the insulator surface.
Inventors
- 👤 M Harding
- 👤 J Payne
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:55
CPC Classifications
H; H01; H01J; H01J19/00; H01J19/42; H01J19/44; H01B; H01B1/00; H01C; H01C7/00; H01C7/003
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
28 words
The invention as defined in claim 1 wherein said ceramic body comprises aluminum oxide and wherein said resistive coating comprises a fired mixture of vanadium-pentoxide and chromium-sesquioxide powders.
Claim 2
Dependent Claim
31 words
The invention as defined in claim 2 wherein said vanadium-pentoxide comprises between 30 and 70 percent by weight of the weight of said resistive material and said chromium-sesquioxide comprises the remainder.
Claim 3
Dependent Claim
47 words
The invention as defined in claim 3 wherein said vanadium-pentoxide and chromium-sesquioxide comprise in original form a powder having a mesh size of between 100 and 300 so as to provide a rough surface, as measured by a stylus profilometer, of 250 to 400 microinches, root-mean-square roughness.
Claim 4
Dependent Claim
33 words
The invention as defined in claim 2 wherein said vanadium-pentoxide comprises 50 percent by weight of said resistive coating and said chromium-sesquioxide the remainder, and wherein said thickness of said coating is 0.002-inch.
Claim 5
Dependent Claim
119 words
An electrical insulator for an electron discharge device which comprises a hollow cylindrical body of ceramic material adapted to receive therewithin a first electrode which protrudes thereinto through one end of said body and adapted to receive therewithin a second electrode which protrudes thereinto through the opposed end of said body and a thick-film, fired-on sintered ceramic electrically resistive coating in a continuous layer over the inner surface of said cylindrical body for providing a resistance of 3 X 108 to 1013 ohms per square so as to prevent the accumulation of electrical charges on said insulator and having a thickness of at least 0.001-inch for preventing penetration of high energy electrons to the surface of the insulator body.
Claim 6
Dependent Claim
17 words
The invention as defined in claim 6 wherein said fired ceramic coating comprises vanadium-pentoxide and chromium-sesquioxide powders.
Claim 7
Dependent Claim
27 words
The invention as defined in claim 6 wherein said coating has a surface roughness of between 250 to 400 microinches, root-mean-square, as measured by a stylus profilometer.
References Cited (Backward Citations)
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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) | 1976-04-23 | 1976-10-23 | 1977-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-23 | 1980-10-23 | 1981-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-23 | 1984-10-23 | 1985-04-24 | $7700.00 | Window Closed / Lapsed |