US4677601A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of forming permanent memory locations in a magnetooptic memory medium
Assignee: Sharp Corp
•
Filing: 1984-03-01
•
Granted: 1987-06-30
•
Expires: 2004-03-01
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
2026-10-26 21:04
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: 8
Claim 1
Independent Claim
68 words
A method for forming permanent memory locations in a magnetic storage medium, comprising the steps of: providing a uniform layer of magnetic-optic material having predetermined physical characteristics, said uniform layer functioning as a changeable and optically readable amorphous magnetic memory medium; and exposing desired locations of said uniform layer to a heat ray to irreversibly form permanent memory locations by changing said physical characteristics at said desired locations.
Claim 2
Independent Claim
68 words
A method for forming permanent memory locations in a magnetic storage medium, comprising the steps of: providing a uniform layer of magnetic-optic material having predetermined physical characteristics, said uniform layer functioning as a changeable and optically readable amorphous magnetic memory medium; and exposing desired locations of said uniform layer to a heat ray to irreversibly form permanent memory locations by changing said physical characteristics at said desired locations.
Claim 3
Dependent Claim
21 words
The method of claim 1, wherein said heat ray is a laser beam which changes the transmittance of said uniform layer.
Claim 4
Dependent Claim
16 words
The method of claim 1, wherein said permanent memory locations are arranged to form guide tracks.
Claim 5
Independent Claim
64 words
A method for forming permanent memory locations in an information storage medium, comprising the steps of: proving a uniform layer of magneto-optic material having predetermined physical characteristics and functioning as a changeable and readable amorphous memory medium; and exposing desired locations of said uniform layer to a heat ray to irreversibly form permanent memory locations by changing said physical characteristics at said desired locations.
Claim 6
Independent Claim
64 words
A method for forming permanent memory locations in an information storage medium, comprising the steps of: proving a uniform layer of magneto-optic material having predetermined physical characteristics and functioning as a changeable and readable amorphous memory medium; and exposing desired locations of said uniform layer to a heat ray to irreversibly form permanent memory locations by changing said physical characteristics at said desired locations.
Claim 7
Dependent Claim
21 words
The method of claim 4, wherein said heat ray is a laser beam which changes the transmittance of said uniform layer.
Claim 8
Dependent Claim
16 words
The method of claim 4, wherein said permanent memory locations are arranged to form guide tracks.
References Cited (Backward Citations)
US3514766A
Cited
US4126494A
Cited
US4202022A
Cited
US4091171A
Cited
US4310899A
Cited
US4412264A
Cited
US4390600A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-06-29 | 1990-12-29 | 1991-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-29 | 1994-12-29 | 1995-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-29 | 1998-12-29 | 1999-06-30 | $7700.00 | Window Closed / Lapsed |