Patent US4777074A successfully refreshed from Google Patents.
US4777074A
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Grooved magnetic substrates and method for producing the same
Assignee: Proterial Ltd
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Filing: 1986-07-24
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Granted: 1988-10-11
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Expires: 2006-07-24
Abstract
Abstract A grooved magnetic substrate including an alumina film layer having a Knoop hardness of 600 kg/mm 2 to 1200 kg/mm 2 charged in at least one groove formed in a surface of a magnetic substrate. The magnetic substrate may be Mn-Zn or NiZn base ferrite. The alumina film layer is formed by sputtering.
Inventors
- 👤 Toshiaki Wada
- 👤 Yoshiaki Katsuyama
- 👤 Junichi Nakaoka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 10:36
CPC Classifications
H; H01; H01F; H01F41/00; H01F41/32; H01F41/34; G; G11; G11B; G11B5/00; G11B5/127; G11B5/31; G11B5/3163; H01F10/00; H01F10/26; H01F10/28; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/4902; Y10T29/49021; Y10T29/49032; Y10T29/49036; Y10T29/49043; Y10T29/4906; Y10T29/49064; Y10T428/00; Y10T428/11; Y10T428/1157; Y10T428/24; Y10T428/24479; Y10T428/24521; Y10T428/24537
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
107 words
A grooved magnetic substrate including an alumina film layer charged in at least one groove formed in a surface of the magnetic substrate wherein a step-like surface irregularity between said magnetic substrate and said alumina film layer is 200 Å or lower, and wherein said groove in said magnetic substrate has a size expressed in terms of a depth (d) of 5 to 50 micrometers, and a ratio of depth (d) width (w) is 1 or lower, and wherein said alumina film layer has a Knoop hardness of 600 Kg/mn 2 to 1200 Kg/mn 2 which is equal to or higher than that of the magnetic substrate.
Claim 2
Dependent Claim
107 words
A grooved magnetic substrate including an alumina film layer charged in at least one groove formed in a surface of the magnetic substrate wherein a step-like surface irregularity between said magnetic substrate and said alumina film layer is 200 Å or lower, and wherein said groove in said magnetic substrate has a size expressed in terms of a depth (d) of 5 to 50 micrometers, and a ratio of depth (d) width (w) is 1 or lower, and wherein said alumina film layer has a Knoop hardness of 600 Kg/mn 2 to 1200 Kg/mn 2 which is equal to or higher than that of the magnetic substrate.
Claim 3
Dependent Claim
19 words
A grooved magnetic substrate as defined in claim 1, wherein said magnetic substrate comprises Mn-Zn or Ni-Zn base ferrite.
Claim 4
Dependent Claim
21 words
A grooved magnetic substrate as defined in claim 1, wherein said alumina film layer is a film layer formed by sputtering.
Claim 5
Dependent Claim
36 words
A grooved magnetic substrate as defined in claim 1, wherein said magnetic substrate is a Mn-Zn base ferrite, and said alumina film layer has a Knoop hardness of 600 kg/mm 2 to 1000 kg/mm 2 .
Claim 6
Dependent Claim
36 words
A grooved magnetic substrate as defined in claim 1, wherein said magnetic substrate is a Ni-Zn base ferrite, and said alumina film layer has a Knoop hardness of 700 kg/mm 2 to 1200 kg/mm 2 .
Claim 7
Dependent Claim
22 words
A grooved magnetic substrate as defined in claim 1, wherein said magnetic substrate has a surface roughness of 100 Å or lower.
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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) | 1991-10-11 | 1992-04-11 | 1992-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-11 | 1996-04-11 | 1996-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-11 | 2000-04-11 | 2000-10-11 | $7700.00 | Window Closed / Lapsed |