US4902584A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical recording medium
Assignee: TDK Corp
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Filing: 1987-12-23
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Granted: 1990-02-20
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Expires: 2007-12-23
Abstract
Abstract An optical recording medium comprising a recording layer on a substrate and a protective layer formed adjacent to the upper or lower surface of the recording layer is more durable and corrosion resistant when the protective layer has a composition comprising silicon, a divalent metal such as Ba, Ca or Sr, oxygen, and nitrogen. An intermediate layer containing silicon, a metal or metalloid such as aluminum or lanthanum, oxygen and nitrogen is formed between the protective layer and the recording layer.
Inventors
- 👤 Kenji Uchiyama
- 👤 Hideki Ishizaki
- 👤 Hajime Utsunomiya
- 👤 Suguru Takayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:36
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/72; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
132 words
A magneto-optical recording medium comprising: a substrate, a recording layer formed on the substrate, said recording layer having upper and lower surfaces disposed remote from and adjacent to the substrate, respectively, and at least one protective layer formed adjacent to the upper or lower surface of said recording layer, said protective layer comprising silicon, at least one divalent metal selected from the group consisting of barium, calcium, magnesium and strontium, oxygen, and nitrogen wherein the silicon is present in the protective layer in an atomic ratio of silicon to the total of silicon and divalent metal of from about 3:10 to about 9:10, wherein the oxygen is present in the protective layer in an atomic ratio of oxygen to the total of oxygen and nitrogen of from about 4:10 to about 8:10.
Claim 2
Dependent Claim
132 words
A magneto-optical recording medium comprising: a substrate, a recording layer formed on the substrate, said recording layer having upper and lower surfaces disposed remote from and adjacent to the substrate, respectively, and at least one protective layer formed adjacent to the upper or lower surface of said recording layer, said protective layer comprising silicon, at least one divalent metal selected from the group consisting of barium, calcium, magnesium and strontium, oxygen, and nitrogen wherein the silicon is present in the protective layer in an atomic ratio of silicon to the total of silicon and divalent metal of from about 3:10 to about 9:10, wherein the oxygen is present in the protective layer in an atomic ratio of oxygen to the total of oxygen and nitrogen of from about 4:10 to about 8:10.
Claim 3
Dependent Claim
27 words
The magneto-optical recording medium of claim 1, wherein the protective layer composition further contains at least one member selected from the group consisting of aluminum and boron.
Claim 4
Dependent Claim
25 words
The magneto-optical recording medium of claim 2, wherein said member is present in an atomic ratio of said member to silicon of up to 1:1.
Claim 5
Dependent Claim
30 words
The magneto-optical recording medium of claim 2, wherein the protective layer composition further contains at least one rare earth element selected from the group consisting of yttrium, lanthanide and actinide.
Claim 6
Dependent Claim
33 words
The magneto-optical recording medium of claim 4, wherein the rare earth element is present in an amount of about 2 to 250 atom % based on the total of silicon and divalent metal.
Claim 7
Dependent Claim
20 words
The magneto-optical recording medium of claim 1, wherein the protective layer is disposed between the substrate and the recording layer.
Claim 8
Dependent Claim
42 words
The magneto-optical recording medium of claim 1, comprising two protective layers wherein one protective layer is disposed adjacent to the upper surface of the recording layer and the other protective layer is disposed adjacent to the lower surface of the recording layer.
Claim 9
Dependent Claim
40 words
The magneto-optical recording medium of claim 1, which further comprises an intermediate layer formed contiguous to the lower surface of said recording layer from at least one member selected from the group consisting of an oxide, carbide, nitride and sulfide.
Claim 10
Dependent Claim
38 words
The magneto-optical recording medium of claim 1 which further comprises an intermediate layer formed contiguous to the lower surface of said recording layer and containing silicon, at least one metal or metalloid other than silicon, oxygen, and nitrogen.
Claim 11
Dependent Claim
21 words
The magneto-optical recording medium of claim 9, wherein the metal or metalloid in the intermediate layer is a rare earth element.
Claim 12
Dependent Claim
20 words
The magneto-optical recording medium of claim 9, wherein the the metal or metalloid in the intermediate layer is an aluminum.
References Cited (Backward Citations)
GB2143689A
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FR2558003A1
Cited
US4661420A
Cited
EP0163810A2
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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) | 1993-02-19 | 1993-08-21 | 1994-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-19 | 1997-08-21 | 1998-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-19 | 2001-08-21 | 2002-02-20 | $7700.00 | Window Closed / Lapsed |