US4467383A
Expired / Lapsed
US
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Magnetooptic memory medium
Assignee: Sharp Corp
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Filing: 1981-02-23
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Granted: 1984-08-21
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Expires: 2001-02-23
Abstract
Abstract Disclosed is a new magnetic storage medium including a layer of amorphous material typically GdDyFe whose Curie recording point (e.g. 120° C.) is lower than its crystallization point (e.g. 350° C.) to enable crystallization to cause variations in its optical properties such as transmittance or reflectivity for thermomagnetic writing. Reversible recordings are set up on the amorphous material layer by a thermomagnetic writing technique, for example Curie point writing, while unchangeable or permanent recordings are set up on the amorphous material layer through laser-activated crystallization of the amorphous material layer.
Inventors
- 👤 Kenji Ohta
- 👤 Toshihisa Deguchi
- 👤 Akira Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 02:11
CPC Classifications
G; G03; G03G; G03G5/00; G03G5/16; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10589; G11B11/10591; G11B7/00; G11B7/08; G11B7/09; G11B7/0938; H; H01; H01F; H01F10/00; H01F10/08; H01F10/10; H01F10/12; H01F10/13; H01F10/133; H01F10/135; H01F10/136; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
23 words
A magnetic storage medium, comprising: a layer of magnetic material having changeable and readable amorphous magnetic memory locations and permanent crystalline memory locations.
Claim 2
Dependent Claim
23 words
A magnetic storage medium, comprising: a layer of magnetic material having changeable and readable amorphous magnetic memory locations and permanent crystalline memory locations.
Claim 3
Dependent Claim
34 words
The magnetic storage medium according to claim 1, wherein information can be stored at said changeable memory locations by exposure of said changeable memory locations to a temperature lower than the crystallization temperature thereof.
Claim 4
Dependent Claim
22 words
The magnetic storage medium according to claim 1, wherein information can be stored at said changeable memory locations by Curie point writing.
Claim 5
Dependent Claim
21 words
The magnetic storage medium according to claim 1, wherein said magnetic material includes a rare earth metal and a transition metal.
Claim 6
Dependent Claim
14 words
The magnetic storage medium according to claim 1, wherein said magnetic material is GdDyFe.
Claim 7
Dependent Claim
14 words
The magnetic storage medium according to claim 1, wherein said magnetic material is GdTbFe.
Claim 8
Dependent Claim
14 words
The magnetic storage medium according to claim 1, wherein said magnetic material is DyFe.
Claim 9
Dependent Claim
14 words
The magnetic storage medium according to claim 1, wherein said magnetic material is TbFe.
Claim 10
Dependent Claim
25 words
A magnetooptical storage medium, comprising: a layer of magnetic material having changeable optically readable amorphous magnetic memory locations and permanent optically readable crystalline memory locations.
Claim 11
Dependent Claim
25 words
A magnetooptical storage medium, comprising: a layer of magnetic material having changeable optically readable amorphous magnetic memory locations and permanent optically readable crystalline memory locations.
Claim 12
Dependent Claim
22 words
The magnetooptical storage medium according to claim 9, wherein information can be stored at said changeable memory locations by Curie point writing.
Claim 13
Dependent Claim
23 words
The magnetooptical storage medium according to claim 9, wherein said layer of magnetic material includes a rare earth metal and a transition metal.
Claim 14
Dependent Claim
22 words
A magnetic storage medium, comprising: a layer of magnetic material having changeable amorphous recording tracks and permanent crystallized guide tracks formed therein.
Claim 15
Dependent Claim
22 words
A magnetic storage medium, comprising: a layer of magnetic material having changeable amorphous recording tracks and permanent crystallized guide tracks formed therein.
Claim 16
Dependent Claim
24 words
A magnetooptical storage medium according to claim 12, wherein said permanent crystallized guide tracks and said changeable amorphous recording tracks can be optically read.
Claim 17
Dependent Claim
22 words
The magnetooptical storage device according to claim 13, wherein said amorphous recording tracks have changeable information stored therein by Curie point writing.
Claim 18
Dependent Claim
18 words
The magnetic storage medium according to claim 12, wherein said recording tracks are flanked with said guide tracks.
Claim 19
Dependent Claim
21 words
A magnetooptical storage medium according to claim 12, wherein said recording tracks are capable of storing information by Curie point writing.
Claim 20
Dependent Claim
17 words
A magnetooptical storage medium according to claim 12, wherein said magnetic material is a layer of GdDyFe.
Claim 21
Dependent Claim
16 words
A magnetooptical storage medium according to claim 12, wherein said layer is a layer of GdTbFe.
Claim 22
Dependent Claim
21 words
The magnetic storage medium according to claim 12, wherein said magnetic material includes a rare earth metal and a transition metal.
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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) | 1987-08-21 | 1988-02-20 | 1988-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-21 | 1992-02-20 | 1992-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-21 | 1996-02-20 | 1996-08-21 | $7700.00 | Window Closed / Lapsed |