Patent US211868A successfully refreshed from Google Patents.
Patent US4609962A successfully refreshed from Google Patents.
US4609962A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium having improved weather resistance
Assignee: Fujifilm Holdings Corp
•
Filing: 1984-04-04
•
Granted: 1986-09-02
•
Expires: 2004-04-04
Abstract
Abstract A metal thin film type magnetic recording medium having an improved weather resistance is disclosed, which comprises a non-magnetic support base having provided thereon a ferromagnetic metal thin film comprised of column-shaped clusters of ferromagnetic particle having longitudinal axes inclined to the surface plane of the support base and a layer of a chromium compound such as Cr and Cr 2 O 3 covering the surfaces of the column-shaped clusters.
Inventors
- 👤 Yoshihiro Arai
- 👤 Akira Nahara
- 👤 Makoto Nagao
- 👤 Kiyotaka Fukino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 00:17
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/64; G11B5/72; G11B5/722; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
126 words
A magnetic recording medium comprising a non-magnetic planar support base having provided thereon: a ferromagnetic metal thin film comprised of column-shaped clusters of ferromagnetic particles having longitudinal axes inclined to the surface plane of the support base, formed by inclined evaporation of the ferromagnetic particles; and a layer of chromium or a chromium compound covering the surfaces of said column-shaped clusters, formed by (i) inclined evaporation of the chromium or chromium compound at an incidence angle of the vapor flow of the chromium or chromium compound in the same direction as that of the incidence angle used to form the ferromagnetic metal thin film, or (ii) vacuum evaporation of the chromium or chromium compound under a pressure ranging from 4×10 -4 Torr to 2×10 -1 Torr.
Claim 2
Dependent Claim
126 words
A magnetic recording medium comprising a non-magnetic planar support base having provided thereon: a ferromagnetic metal thin film comprised of column-shaped clusters of ferromagnetic particles having longitudinal axes inclined to the surface plane of the support base, formed by inclined evaporation of the ferromagnetic particles; and a layer of chromium or a chromium compound covering the surfaces of said column-shaped clusters, formed by (i) inclined evaporation of the chromium or chromium compound at an incidence angle of the vapor flow of the chromium or chromium compound in the same direction as that of the incidence angle used to form the ferromagnetic metal thin film, or (ii) vacuum evaporation of the chromium or chromium compound under a pressure ranging from 4×10 -4 Torr to 2×10 -1 Torr.
Claim 3
Dependent Claim
31 words
A magnetic recording medium as claimed in claim 1, wherein the column-shaped clusters of ferromagnetic particles have a diameter in the range of from about 20 Å to about 1,000 Å.
Claim 4
Dependent Claim
29 words
A magnetic recording medium as claimed in claim 2, wherein the ferromagnetic metal thin film has a thickness in the range of from about 200 to about 5,000 Å.
Claim 5
Dependent Claim
32 words
A magnetic recording medium as claimed in claim 1, wherein the ferromagnetic metal thin film is comprised of cobalt or an alloy containing cobalt in a proportion of 75 wt% or more.
Claim 6
Dependent Claim
27 words
A magnetic recording medium as claimed in claim 1, wherein the chromium compound is selected from the group consisting of chromium oxides, chromium carbides and chromium nitrides.
Claim 7
Dependent Claim
19 words
A magnetic recording medium as claimed in claim 5, wherein the chromium compound is Cr 2 O 3 .
Claim 8
Dependent Claim
25 words
A magnetic recording medium as claimed in claim 1, wherein a lubricant layer is further provided on the layer of the chromium or chromium compound.
Claim 9
Dependent Claim
29 words
A magnetic recording medium as claimed in claim 7, wherein the lubricant layer is formed of a higher fatty acid, a higher fatty acid ester or a combination thereof.
Claim 10
Dependent Claim
26 words
A magnetic recording medium as claimed in claim 1, wherein the layer of chromium or a chromium compound is formed of Cr 2 O 3 .
Claim 11
Dependent Claim
22 words
A magnetic recording medium as claimed in claim 1, wherein the layer of chromium or a chromium compound is formed of chromium.
References Cited (Backward Citations)
US4246316A
Cited
US4503119A
Cited
JPS5718025A
Cited
JPS5792401A
Cited
US4414271A
Cited
US4455345A
Cited
US4448837A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-09-01 | 1990-03-03 | 1990-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-09-01 | 1994-03-03 | 1994-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-09-01 | 1998-03-03 | 1998-09-02 | $7700.00 | Window Closed / Lapsed |