EP0061584A1
Expired / Lapsed
EP
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Pregrooved optical-disk
Assignee: Toshiba Corp
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Filing: 1982-02-24
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Granted: —
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Expires: 2002-02-24
Abstract
Abstract The optical-disk (50) has a transparent substrate (52) which has a surface in which a tracking groove (54) is formed and which is made of a polymethyl methacrylate having a refractive index n 1 of about 1.49, a transparent layer (56) of polystyrene which is formed on the transparent substrate (52) and which has a refractive index n 2 of about 1.59, and a recording layer (58) which is formed on the transparent layer (56) of polystyrene and which is made of a substance which is melted by a pulse laser beam (44) for recording, which becomes incident thereon through the transparent substrate (52) and the transparent layer (56) of polystyrene.
Inventors
- 👤 Teruo Murakami
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 04:09
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/26; G11B7/241; G11B7/252; G11B7/257; G11B7/2572; G11B7/2575; G11B7/242; G11B7/243; G11B2007/24302; G11B2007/24316; G11B7/254; G11B2007/25408; G11B2007/25417; G11B7/253; G11B7/2531; G11B7/2533; G11B7/2542
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
193 words
A pregrooved optical-disk which has a tracking groove (54) formed in advance, which records information in a region of a recording layer (58) corresponding to said groove (54) by an energy beam such as laser including information to be recorded, and in which tracking control is performed with reference to said tracking groove (54), said recording layer (58) being made of a substance which is melted by said energy beam when an energy level of the energy beam exceeds a predetermined level, characterized by comprising a first layer (52, 66) which has a surface in which the tracking groove (54) is formed and which is made of a transparent substance having a first refractive index n l , and a second layer (56, 64) which is provided on the surface of said first layer (52, 66) and which is made of a transparent material having a second refractive index n 2 ; and characterized in that said recording layer (58) is provided on said second layer (56, 64), and said energy beam is incident on said recording layer (58) through at least said first layer (52, 66) and said second layer (56, 64).
Claim 2
Dependent Claim
193 words
A pregrooved optical-disk which has a tracking groove (54) formed in advance, which records information in a region of a recording layer (58) corresponding to said groove (54) by an energy beam such as laser including information to be recorded, and in which tracking control is performed with reference to said tracking groove (54), said recording layer (58) being made of a substance which is melted by said energy beam when an energy level of the energy beam exceeds a predetermined level, characterized by comprising a first layer (52, 66) which has a surface in which the tracking groove (54) is formed and which is made of a transparent substance having a first refractive index n l , and a second layer (56, 64) which is provided on the surface of said first layer (52, 66) and which is made of a transparent material having a second refractive index n 2 ; and characterized in that said recording layer (58) is provided on said second layer (56, 64), and said energy beam is incident on said recording layer (58) through at least said first layer (52, 66) and said second layer (56, 64).
Claim 3
Dependent Claim
56 words
A pregrooved optical-disk according to claim 1, characterized in that, difference An between the first refractive index n 1 of said first layer (52, 66) and the second refractive index n 2 of said second layer (56, 64) is substantially equal to: and said difference An is preferably set in a range of 0.01 to 0.5.
Claim 4
Dependent Claim
24 words
A pregrooved optical-disk according to claim 2, characterized in that said difference Δn is more preferably set in a range of 0.02 to 0.2.
Claim 5
Dependent Claim
38 words
A pregrooved optical-disk according to claim 1, characterized in that said first layer (52, 66), said second layer (56, 64), and said recording layer (58) are combined in the form of a disk having a substantially predetermined thickness.
Claim 6
Dependent Claim
25 words
A pregrooved optical-disk according to claim 4, characterized in that said tracking groove (54) is formed to extend in a circumferential direction of said disk.
Claim 7
Dependent Claim
38 words
A pregrooved optical-disk according to claim 1, characterized in that said first layer (52) is made of a transparent substrate having the refractive index n l , and said second layer (56) is formed on said transparent substrate.
Claim 8
Dependent Claim
26 words
A pregrooved optical-disk according to claim 1, characterized by further comprising protective layer means (60, 62) for protecting said recording layer (58) from the external atmosphere.
Claim 9
Dependent Claim
44 words
A pregrooved optical-disk according to claim 7, characterized in that said protective layer means (62) is formed of a predetermined substrate; and said recording layer (58), said second layer (64) and said first layer (66) are sequentially formed on one surface of said substrate.
Claim 10
Dependent Claim
53 words
A pregrooved optical-disk according to claim 8, characterized in that said second layer (64) has on a surface thereof a projection corresponding to said tracking groove (54) of said first layer (66), and said first layer (66) is formed on the surface of said second layer (64) on which is formed said projection.
References Cited (Backward Citations)
JPS5210102A
Cited
GB2016747A
Cited
DE2944744A1
Cited
GB2036410A
Cited
JPS5634154A
Cited
JPS5661047A
Cited
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