US4239835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: Panasonic Holdings Corp
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Filing: 1977-07-13
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Granted: 1980-12-16
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Expires: 1997-07-13
Abstract
Abstract A magnetic recording medium wherein a ferromagnetic substance consisting of Fe, Co, Ni or alloy thereof is vacuum evaporated and deposited on a substrate made of a plastic film or a sheet of non-magnetic metal. The thin ferromagnetic film has the columnar crystal structure, and the columnar crystals are coated with a layer of oxide of the ferromagnetic substance.
Inventors
- 👤 Yasuo Iijima
- 👤 Koichi Shinohara
- 👤 Takashi Fujita
- 👤 Masaru Odagiri
- 👤 Toshiaki Kunieda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:07
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B5/84; G11B5/85; H; H01; H01F; H01F41/00; H01F41/14; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/922; Y10S428/9265; Y10S428/928; Y10T; Y10T428/00; Y10T428/12; Y10T428/12465; Y10T428/12493; Y10T428/12535; Y10T428/12556; Y10T428/12569; Y10T428/12611; Y10T428/12736; Y10T428/1275; Y10T428/12757; Y10T428/12771; Y10T428/12861; Y10T428/12931; Y10T428/12944; Y10T428/19; Y10T428/192; Y10T428/197; Y10T428/198; Y10T428/31504; Y10T428/31678
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
85 words
A thin metal film type magnetic recording medium which comprises a plastic film or non-magnetic metal substrate, a thin film less than about 3000 A thick of a ferromagnetic metal or alloy having a columnar crystal structure inclined at an angle of less than 60° relative to the normal to said substrate wherein the columnar crystals are substantially the same height, having been continuously formed by vacuum deposition, and a layer of an oxide of a ferromagnetic metal or alloy coated on said columnar crystals.
Claim 2
Dependent Claim
85 words
A thin metal film type magnetic recording medium which comprises a plastic film or non-magnetic metal substrate, a thin film less than about 3000 A thick of a ferromagnetic metal or alloy having a columnar crystal structure inclined at an angle of less than 60° relative to the normal to said substrate wherein the columnar crystals are substantially the same height, having been continuously formed by vacuum deposition, and a layer of an oxide of a ferromagnetic metal or alloy coated on said columnar crystals.
Claim 3
Dependent Claim
50 words
A thin metal film type magnetic recording medium as set forth in claim 1 wherein said thin ferromagnetic film is made of iron, cobalt, nickel or alloy thereof, and has a volume resistivity in excess of 1.2 times as high as the volume resistivity of the composition metal or alloy.
Claim 4
Dependent Claim
42 words
A thin metal film type magnetic recording medium as set forth in claim 1 wherein said substrate is coated with a layer of aluminum or aluminum oxide, and said thin ferromagnetic film is deposited upon said layer of aluminum or aluminum oxide.
Claim 5
Dependent Claim
42 words
A thin metal film type magnetic recording medium as set forth in claim 2 wherein said substrate is coated with a layer of aluminum or aluminum oxide, and said thin ferromagnetic film is deposited on said layer of aluminum or aluminum oxide.
Claim 6
Dependent Claim
24 words
The magnetic recording medium of claim 1 wherein the ratio of the height to width of said columnar crystal structure is at least 3:1.
Claim 7
Dependent Claim
21 words
The magnetic recording medium of claim 6 wherein the ferromagnetic metal is selected from the group consisting of Fe and Co.
Claim 8
Dependent Claim
23 words
The magnetic recording medium of claim 1 wherein the thin film of ferromagnetic material is from about 300 A to 3000 A thick.
Claim 9
Dependent Claim
83 words
A thin metal film type magnetic recording medium which comprises a plastic film or non-magnetic metal substrate, a thin film less than about 3000 A thick of a ferromagnetic metal or alloy having a crystal structure in the form of discrete columnar structures inclined at an angle less than 60° relative to the normal to said substrate wherein the columnar crystals are substantially the same height and a layer of an oxide of a ferromagnetic metal or alloy on said discrete columnar structure.
Claim 10
Dependent Claim
83 words
A thin metal film type magnetic recording medium which comprises a plastic film or non-magnetic metal substrate, a thin film less than about 3000 A thick of a ferromagnetic metal or alloy having a crystal structure in the form of discrete columnar structures inclined at an angle less than 60° relative to the normal to said substrate wherein the columnar crystals are substantially the same height and a layer of an oxide of a ferromagnetic metal or alloy on said discrete columnar structure.
Claim 11
Dependent Claim
21 words
The magnetic recording medium of claim 8 wherein the ferromagnetic metal is selected from the group consisting of Fe and Co.
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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) | 1983-12-16 | 1984-06-16 | 1984-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-16 | 1988-06-16 | 1988-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-16 | 1992-06-16 | 1992-12-16 | $7700.00 | Window Closed / Lapsed |