US4664977A
Expired / Lapsed
US
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Opto-magnetic recording medium
Assignee: Canon Inc
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Filing: 1985-03-29
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Granted: 1987-05-12
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Expires: 2005-03-29
Abstract
Abstract An opto-magnetic recording medium comprises a recording layer formed of a magnetic film having a readily magnetizable axis in a direction perpendicular to the surface of the film, and a reflective and phase modulating layer provided in contact with the recording layer. The reflective and phase modulating layer is formed so that the imaginary number portion (k) of the refractive index gradually increases in the direction of thickness away from that side which is in contact with the recording layer.
Inventors
- 👤 Yoichi Osato
- 👤 Eiichi Fujii
- 👤 Ichiro Saito
- 👤 Kozo Arao
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:50
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10589; G11B11/10593; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
84 words
An opto-magnetic recording medium comprising: a recording layer formed of a magnetic film having a readily magnetizable axis in a direction perpendicular to the surface of the film; and a reflective and phase modulating layer provided in contact with said recording layer, said reflective and phase modulating layer being a single layer and formed so that the imaginary number portion (k) of the refractive index gradually increases in the direction of thickness away from that side which is in contact with said recording layer.
Claim 2
Dependent Claim
84 words
An opto-magnetic recording medium comprising: a recording layer formed of a magnetic film having a readily magnetizable axis in a direction perpendicular to the surface of the film; and a reflective and phase modulating layer provided in contact with said recording layer, said reflective and phase modulating layer being a single layer and formed so that the imaginary number portion (k) of the refractive index gradually increases in the direction of thickness away from that side which is in contact with said recording layer.
Claim 3
Dependent Claim
25 words
An opto-magnetic recording medium according to claim 1, wherein the thickness of said reflective and phase modulating layer is in the range of 20-10,000 Å.
Claim 4
Dependent Claim
24 words
An opto-magnetic recording medium according to claim 1, wherein said recording layer comprises a thin film of an amorphous alloy of rare earth-transition metal.
Claim 5
Dependent Claim
22 words
An opto-magnetic recording medium according to claim 1, wherein the thickness of said recording layer is in the range of 100-1000 Å.
Claim 6
Dependent Claim
89 words
An opto-magnetic recording medium according to claim 1, wherein said reflective and phase modulating layer comprises a mixture of a substantce having a small absorption for the wavelength of light used to reproduce information from the recording medium and a substance having a great reflection for said wavelength of light, and is formed so that the content of the substance of great reflection relative to the whole gradually increases in the direction of thickness of the layer away from the side which is in contact with said recording layer.
Claim 7
Dependent Claim
40 words
An opto-magnetic recording medium according to claim 5, wherein said substance having a small absorption comprises a dielectric material selected from the group consisting of oxides of metal, oxides of semi-metal, fluorides, sulfides, iodides and organic high molecular weight material.
Claim 8
Dependent Claim
18 words
An opto-magnetic recording medium according to claim 5, wherein said substance having a great reflection comprises a metal.
Claim 9
Dependent Claim
34 words
An opto-magnetic recording medium according to claim 5, wherein reflective and phase modulating layer is formed by a vapor deposition of the substance having a small absorption and the substance having a great reflection.
Claim 10
Dependent Claim
26 words
An opto-magnetic recording medium according to claim 1, comprising said recording layer and said reflective and phase modulating layer formed in succession on a light-transmitting substrate.
Claim 11
Dependent Claim
31 words
An opto-magnetic recording medium according to claim 9, wherein a protective layer is provided on that side of said reflective and phase modulating layer which is opposite to the light-transmitting substrate.
Claim 12
Dependent Claim
22 words
An opto-magnetic recording medium according to claim 9, wherein an adiabatic layer is provided between said light-transmitting substrate and said recording layer.
Claim 13
Dependent Claim
22 words
An opto-magnetic recording medium according to claim 9, wherein an anti-reflection film is provided between said light-transmitting substrate and said recording layer.
References Cited (Backward Citations)
JPS586542A
Cited
JPS586541A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-11 | 1990-11-10 | 1991-05-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-11 | 1994-11-10 | 1995-05-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-11 | 1998-11-10 | 1999-05-12 | $7700.00 | Window Closed / Lapsed |