US4943957A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High-density information recording carrier
Assignee: Daicel Corp
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Filing: 1988-10-17
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Granted: 1990-07-24
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Expires: 2008-10-17
Abstract
Abstract A high-density information recording carrier such as an optical disk which is used for recording and/or playing back information carried on a plastic substrate by means of laser beams has an improved protective layer between a recording layer and the plastic substrate. The protective layer is made of inorganic glass made of alkali-free glass containing less than 1 wt % of alkali metal oxides. The resulting optical disk shows improved durability, higher C/N, lower BER and higher film forming rate.
Inventors
- 👤 Masaru Sato
- 👤 Nagayoshi Tsukane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 00:52
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B7/00; G11B7/24; G11B7/241; G11B7/252; G11B7/257; G11B7/2578; G11B7/242; G11B7/243; G11B2007/24302; G11B2007/24306; G11B2007/25705; G11B2007/25706; G11B2007/25708; G11B2007/2571; G11B2007/25715; G11B7/253; G11B7/2533; G11B7/2534; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
113 words
An optical information recording carrier comprising a transparent plastic substrate, an information recording layer formed on the substrate, and a layer of inorganic glass interposed between the substrate and the recording layer; the recording layer being a magneto-optical rare earth-transition metal amorphous alloy, and said layer of inorganic glass having a thickness of from 100 to 2000 Angstroms and being a glass comprising oxides and having an alkali metal content of less than 1 wt% in terms of alkali metal oxides and a coefficient of linear expansion of 40 to 70×10 -7 /° C., and containing from 20 wt% to 35 wt% of alkaline earth metals in terms of alkaline earth metal oxides.
Claim 2
Dependent Claim
113 words
An optical information recording carrier comprising a transparent plastic substrate, an information recording layer formed on the substrate, and a layer of inorganic glass interposed between the substrate and the recording layer; the recording layer being a magneto-optical rare earth-transition metal amorphous alloy, and said layer of inorganic glass having a thickness of from 100 to 2000 Angstroms and being a glass comprising oxides and having an alkali metal content of less than 1 wt% in terms of alkali metal oxides and a coefficient of linear expansion of 40 to 70×10 -7 /° C., and containing from 20 wt% to 35 wt% of alkaline earth metals in terms of alkaline earth metal oxides.
Claim 3
Dependent Claim
28 words
An optical information recording carrier as set forth in claim 1, wherein the amount of alkali metals is less than 0.8 wt% in terms of alkali metal oxides.
Claim 4
Dependent Claim
34 words
An optical information recording carrier as set forth in claim 2, wherein said alkaline earth metal oxide is at least one compound selected from a group consisting of BaO, CaO, MgO, SrO and BeO.
Claim 5
Dependent Claim
28 words
An optical information recording carrier as set forth in any one of claims 1, 2 and 3, wherein said information recording layer is made of magneto-optical recording material.
Claim 6
Dependent Claim
27 words
An optical information recording carrier as set forth in claim 1, wherein said magneto-optical recording material is amorphous alloy composed of rare earth elements and transition metals.
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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) | 1993-07-23 | 1994-01-22 | 1994-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-23 | 1998-01-22 | 1998-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-23 | 2002-01-22 | 2002-07-24 | $7700.00 | Window Closed / Lapsed |