EP0329425A2
Expired / Lapsed
EP
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Optical recording medium and manufacturing method thereof
Assignee: Sharp Corp
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Filing: 1989-02-15
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Granted: —
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Expires: 2009-02-15
Abstract
Abstract A novel optical recording medium and a method for manufacture thereof is disclosed, the optical recording medium, which is used as an optical disc or optical card et cetera for optically recording, reproducing, erasing and the like of information, comprising a center substrate having formed on at least either of both sides thereof recesses and/or protrusions, recording films formed on both sides thereof and transparent protective plates stuck to these recording films respectively, and featuring special arrangements to ensure against warping of the substrates constituting the optical recording medium and also against exfoliation of substrates or the like even when the optical recording medium is subjected to sudden changes in temperature as well as to allow placing emphasis on optical performance and protective effect in selecting the transparent protective plate regardless of the ease of forming recesses and/or protrusions such as grooves to thereby enable a marked improvement in its performance such as carrier-to-noise ratio and isotropy.
Inventors
- 👤 Akira Takahashi
- 👤 Michinobu Mieda
- 👤 Yoshiteru Murakami
- 👤 Junichiro Nakayama
- 👤 Tomoyuki Miyake
- 👤 Kenji Ohta
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 08:19
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10584; G11B7/00; G11B7/24; G11B7/26; Y; Y10; Y10S; Y10S430/00; Y10S430/146; Y10T; Y10T428/00; Y10T428/23; Y10T428/239; Y10T428/24; Y10T428/24479; Y10T428/24521; Y10T428/24529; Y10T428/31504; Y10T428/31507
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
38 words
An optical recording medium, comprising a center substrate, of whose both sides at least either has recesses and/or protrusions formed therein, recording films formed on both sides thereof and transparent protective plates stuck to these recording films respectively.
Claim 2
Dependent Claim
38 words
An optical recording medium, comprising a center substrate, of whose both sides at least either has recesses and/or protrusions formed therein, recording films formed on both sides thereof and transparent protective plates stuck to these recording films respectively.
Claim 3
Dependent Claim
20 words
An optical recording medium according to claim 1, wherein said center substrate is of polycarbonate resin formed by injection molding.
Claim 4
Dependent Claim
21 words
An optical recording medium according to claim 1, wherein said center substrate is of a synthetic resin formed by cast molding.
Claim 5
Dependent Claim
21 words
An optical recording medium according to claim 1, wherein said transparent protective plate is of polycarbonate resin formed by extrusion molding.
Claim 6
Dependent Claim
17 words
An optical recording medium according to claim 1, wherein said transparent protective plate is made of glass.
Claim 7
Dependent Claim
26 words
An optical recording medium according to claim 1, wherein said center substrate and said transparent protective plate are made of materials similar in thermal expansion coefficient.
Claim 8
Dependent Claim
33 words
An optical recording medium according to claim 6, wherein said center substrate is of polycarbonate resin formed by injection molding, while said transparent protective plate is of polycarbonate resin formed by extrusion molding.
Claim 9
Independent Claim
49 words
A method of manufacturing an optical recording medium comprising the steps of first preparing a center substrate with recesses and/or protrusions formed at least on one side thereof, then forming recording films on both sides of said substrate and thereafter sticking transparent, protective plates to said recording films respectively.
Claim 10
Independent Claim
49 words
A method of manufacturing an optical recording medium comprising the steps of first preparing a center substrate with recesses and/or protrusions formed at least on one side thereof, then forming recording films on both sides of said substrate and thereafter sticking transparent, protective plates to said recording films respectively.
Claim 11
Dependent Claim
53 words
A method of manufacturing an optical recording medium according to claim 8, wherein said center substrate is made by injection molding and in the course of said injection molding recesses and/or protrusions are formed by means of a pair of stampers attached to the die on both sides of said center substrate simultaneously.
Claim 12
Dependent Claim
55 words
A method of manufacturing an optical recording medium according to claim 8, wherein a material is first formed as a plate by extrusion molding and placing this material plate between a pair of dies and pressing inward from both sides to thereby form said recesses and/or protrusions on both sides of said center substrate simultaneously.
Claim 13
Dependent Claim
32 words
A double-sided optical recording medium having recording layers formed on respective opposite sides of a centre substrate and respective transparent outer protective plates disposed to the outer sides of said recording layers.
Claim 14
Dependent Claim
32 words
A double-sided optical recording medium having recording layers formed on respective opposite sides of a centre substrate and respective transparent outer protective plates disposed to the outer sides of said recording layers.
Claim 15
Dependent Claim
46 words
A double-sided optical recording medium in which guide grooves are formed on opposite sides of a centre substrate, and recording layers are disposed between said opposite sides of the centre substrate and respective outer protective plates, the inner faces of said protective plates being substantially flat.
Claim 16
Dependent Claim
46 words
A double-sided optical recording medium in which guide grooves are formed on opposite sides of a centre substrate, and recording layers are disposed between said opposite sides of the centre substrate and respective outer protective plates, the inner faces of said protective plates being substantially flat.
References Cited (Backward Citations)
No citation records indexed.
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