Patent US4822675A successfully refreshed from Google Patents.
US4822675A
Expired / Lapsed
US
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Stable magneto optic recording medium
Assignee: 3M Co
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Filing: 1988-03-31
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Granted: 1989-04-18
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Expires: 2008-03-31
Abstract
Abstract Magneto-optic recording media have been made more resistant to corrosion by incorporating small amounts of tantalum and/or yttrium into the rare earth-transition metal active layer of the recording media. This improvement should help make magneto-optic media more reliable in the long term storage and retrieval of information.
Inventors
- 👤 Arnold W. Funkenbusch
- 👤 David W. Siitari
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 16:11
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10589; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
87 words
A magneto-optical recording medium comprising a substrate containing an element selected from the group consisting of sulfur and chlorine, a magnetizable rare earth-transition metal alloy layer on the substrate which alloy layer is protected from contact with the ambient atmosphere by a layer or layers on all sides, and a reflective surface located to reflect light through the magnetizable alloy layer, wherein the magnetizable alloy comprises a combination of an iron-terbium alloy and an added metal selected from the group consisting of yttrium, tantalum, and combinations thereof.
Claim 2
Dependent Claim
87 words
A magneto-optical recording medium comprising a substrate containing an element selected from the group consisting of sulfur and chlorine, a magnetizable rare earth-transition metal alloy layer on the substrate which alloy layer is protected from contact with the ambient atmosphere by a layer or layers on all sides, and a reflective surface located to reflect light through the magnetizable alloy layer, wherein the magnetizable alloy comprises a combination of an iron-terbium alloy and an added metal selected from the group consisting of yttrium, tantalum, and combinations thereof.
Claim 3
Dependent Claim
15 words
The magneto-optical recording medium of claim 1 wherein the rare earth-transition metal alloy contains cobalt.
Claim 4
Dependent Claim
15 words
The magneto-optical recording medium of claim 1 wherein the rare earth-transition metal alloy is amorphous.
Claim 5
Dependent Claim
37 words
The magneto-optical recording medium of claim 1 wherein the concentration of yttrium in the alloy is no more than 5 atom percent, and the concentration of tantalum in the alloy is no more than 5 atom percent.
Claim 6
Dependent Claim
24 words
The magneto-optical recording medium of claim 1 wherein the thickness of the magnetizable rare earth-transition metal alloy layer is between 50 and 2000 angstroms.
Claim 7
Dependent Claim
73 words
A magneto-optical recording medium comprising a substrate containing an element selected from the group consisting of sulfur and chlorine, a magnetizable rare earth-transition metal alloy layer on the substrate which alloy layer is protected from contact with the ambient atmosphere by a layer or layers on all sides, and a reflective surface located to reflect light through the magnetizable alloy layer, wherein the magnetizable alloy comprises an alloy of iron, terbium and yttrium.
Claim 8
Dependent Claim
73 words
A magneto-optical recording medium comprising a substrate containing an element selected from the group consisting of sulfur and chlorine, a magnetizable rare earth-transition metal alloy layer on the substrate which alloy layer is protected from contact with the ambient atmosphere by a layer or layers on all sides, and a reflective surface located to reflect light through the magnetizable alloy layer, wherein the magnetizable alloy comprises an alloy of iron, terbium and yttrium.
Claim 9
Dependent Claim
17 words
The magneto-optical recording medium of claim 6 wherein the magnetizable alloy comprises iron, terbium, cobalt and yttrium.
Claim 10
Dependent Claim
73 words
A magneto-optical recording medium comprising a substrate containing an element selected from the group consisting of sulfur and chlorine, a magnetizable rare earth-transition metal alloy layer on the substrate which alloy layer is protected from contact with the ambient atmosphere by a layer or layers on all sides, and a reflective surface located to reflect light through the magnetizable alloy layer, wherein the magnetizable alloy comprises an alloy of iron, terbium and tantalum.
Claim 11
Dependent Claim
73 words
A magneto-optical recording medium comprising a substrate containing an element selected from the group consisting of sulfur and chlorine, a magnetizable rare earth-transition metal alloy layer on the substrate which alloy layer is protected from contact with the ambient atmosphere by a layer or layers on all sides, and a reflective surface located to reflect light through the magnetizable alloy layer, wherein the magnetizable alloy comprises an alloy of iron, terbium and tantalum.
Claim 12
Dependent Claim
16 words
The magneto-optical recording medium of claim 8 wherein the magnetizable alloy comprises iron, terbium, cobalt, tantalum.
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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) | 1992-04-17 | 1992-10-17 | 1993-04-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-17 | 1996-10-17 | 1997-04-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-17 | 2000-10-17 | 2001-04-18 | $7700.00 | Window Closed / Lapsed |