US4908250A
Expired / Lapsed
US
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Optical recording medium and production method thereof
Assignee: Hitachi Ltd
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Filing: 1988-09-19
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Granted: 1990-03-13
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Expires: 2008-09-19
Abstract
Abstract In an optical recording medium, an under layer is formed between an even pattern of a substrate and a recording layer, and said under layer is made of a high polymeric material which can be melted, sublimated, or decomposed at a lower temperature than the melting point, the sublimating point, or the decomposing temperature of said recording layer. Accordingly, said under layer can relax the thermal shock transferred from said substrate into said recording layer, and the deformation of said substrate can be prevented, even through a laser beam for playback is repeatedly radiated onto said recording layer, and said optical recording medium has a larger recording sensitivity than the recording sensitivity of an optical recording disc of a prior art.
Inventors
- 👤 Akira Gotoh
- 👤 Yukinobu Yamazaki
- 👤 Naoyuki Kikuchi
- 👤 Shinkichi Horigome
- 👤 Motoyasu Terao
- 👤 Hiroyuki Suzuki
- 👤 Makoto Kitoh
- 👤 Yuichi Kokaku
- 👤 Mitsuru Shimizu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 02:00
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/252; G11B7/257; G11B7/2572; G11B7/2575; G11B7/26; G11B7/242; G11B7/243; G11B2007/24302; G11B2007/24312; G11B2007/24316; G11B7/253; G11B7/2533; G11B7/2534; Y; Y10; Y10S; Y10S428/00; Y10S428/913; Y10S430/00; Y10S430/146; Y10T; Y10T428/00; Y10T428/26; Y10T428/261; Y10T428/266; Y10T428/31504; Y10T428/31507; Y10T428/31511; Y10T428/3154; Y10T428/31544; Y10T428/31678; Y10T428/31681; Y10T428/31692; Y10T428/31721; Y10T428/31786; Y10T428/31826; Y10T428/3183
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
141 words
An optical recording medium consisting essentially of: a disc substrate having an uneven grooved pattern preformed on one surface thereof; an under layer formed on said uneven pattern of said disc substrate having a thickness of from 100 to 800 Å , said under layer consisting essentially of a high polymeric material having a first temperature at which said high polymeric material can be melted, sublimated, or decomposed, a heat resistance superior to said disc substrate and a lower heat conductivity than said substrate; and a recording layer provided on said under layer, consisting essentially of a recording material having a second temperature at which said recording material can be melted, sublimated or decomposed; said first temperature being lower than said second temperature; said under layer being provided for relaxing thermal shock transmitted from said recording layer to said disc substrate.
Claim 2
Dependent Claim
141 words
An optical recording medium consisting essentially of: a disc substrate having an uneven grooved pattern preformed on one surface thereof; an under layer formed on said uneven pattern of said disc substrate having a thickness of from 100 to 800 Å , said under layer consisting essentially of a high polymeric material having a first temperature at which said high polymeric material can be melted, sublimated, or decomposed, a heat resistance superior to said disc substrate and a lower heat conductivity than said substrate; and a recording layer provided on said under layer, consisting essentially of a recording material having a second temperature at which said recording material can be melted, sublimated or decomposed; said first temperature being lower than said second temperature; said under layer being provided for relaxing thermal shock transmitted from said recording layer to said disc substrate.
Claim 3
Dependent Claim
20 words
The optical recording medium of claim 1, wherein said high polymeric material is selected from a fluorocarbon resin or polyimide.
Claim 4
Dependent Claim
14 words
The optical recording medium of claim 2, wherein said high polymeric material is transparent.
Claim 5
Dependent Claim
32 words
The optical recording medium of claim 1, wherein said high polymeric material is at least one compound selected from the group consisting of polyolefin fluoride, halogenide of polyolefin fluoride, and graphite fluoride.
Claim 6
Dependent Claim
37 words
The optical recording medium of claim 1, wherein said high polymeric material is at least one compound selected from the group consisting of polytetrafluoroethylene, polyvenyl fluoride, polytrifluoroethylene, polyvinylidene fluoride, polyhexafluoropropylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, polycarbon monfluoride and polydicarbon monofluoride.
Claim 7
Dependent Claim
36 words
The optical recording medium of claim 1, wherein said high polymeric material has a heat resistance at a higher temperature than 110° C., and said high polymeric material has a lower heat conductivity than 5 W/mK.
Claim 8
Dependent Claim
19 words
The optical recording medium of claim 1, wherein the thickness of said under layer is greater than 200 Å.
Claim 9
Dependent Claim
33 words
The optical recording medium of claim 1, wherein said substrate is selected from polycarbonate, polymethylmethacrylate or epoxy resin, and said recording layer is made of a tellurium alloy having a low melting point.
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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) | 1993-03-12 | 1993-09-11 | 1994-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-12 | 1997-09-11 | 1998-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-12 | 2001-09-11 | 2002-03-13 | $7700.00 | Window Closed / Lapsed |