EP0527602A2
Expired / Lapsed
EP
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Optical memory
Assignee: Sharp Corp
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Filing: 1992-08-07
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Granted: —
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Expires: 2012-08-07
Abstract
Abstract A transparent substrate of an optical memory is produced by injection molding using a stamper. Grooves and lands are alternately arranged on the optical memory, for tracking of light converged on the optical memory. The groove width is set in the range of 0.3 µm to 0.4 µm and the groove depth is set in the range of 80 nm to 100 nm. A decrease in the width of a land at each edge is restrained to 0.2 µm in maximum. With such dimensions, even when the track pitch is set to about 1.4 µm, it is possible to obtain a track crossing signal with intensity sufficient for performing an access operation to a target track. Moreover, since the dimensions bring about an improved reflectance at a land, the optical memory achieves an improved C/N and recording density.
Inventors
- 👤 Tetsuya Inui
- 👤 Akira Takahashi
- 👤 Kenji Ohta
- 👤 Michinobu Mieda
- 👤 Yoshiteru Murakami
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 09:17
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/26; G11B7/261; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B7/2407; G11B7/24073; G11B7/24079; G11B7/004; G11B7/0045; G11B7/00454; G11B7/007; G11B7/08; G11B7/09; G11B7/0938
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
84 words
An optical memory, comprising a substrate having thereon tracks formed by alternately arranged grooves and lands, said grooves and lands being provided so as to perform tracking of light converged on said optical memory, wherein a groove width is set in the range of 0.3 µm to 0.4 µm, a groove depth is set in the range of 80 nm to 100 nm, and the maximum limit for a decrease in the width of said land at each edge is set to 0.2 µm.
Claim 2
Dependent Claim
19 words
The optical memory according to claim 1, wherein said grooves are formed with a track pitch of 1.4 µm.
Claim 3
Dependent Claim
31 words
The optical memory according to claim 1, further comprising a recording layer on or from which information is optically recorded, reproduced and erased, said recording layer being formed on said substrate.
Claim 4
Dependent Claim
40 words
The optical memory according to claim 3, wherein said recording layer is made from a magneto-optical arterial, and wherein information is recorded, reproduced and erased on or from said recording layer by using the magneto-optical effects of said magneto-optical material.
Claim 5
Dependent Claim
44 words
The optical memory according to claim 3, wherein said recording layer is made from a phase-change material, and wherein information is recorded, reproduced and erased on or from said recording layer by using a phase change of said phase-change material between crystal and amorphous.
Claim 6
Dependent Claim
39 words
The optical memory according to claim 3, wherein said recording layer is made from a write-once type material, and wherein information is recorded, reproduced and erased on or from said recording layer by using pits formed by recording energy.
Claim 7
Dependent Claim
40 words
The optical memory according to claim 3, wherein said recording layer is made from a recording material, and wherein information is recorded, reproduced and erased on or from said recording layer by using the photochromic effects of said recording material.
Claim 8
Independent Claim
123 words
A method of manufacturing a stamper used for producing a substrate of an optical memory, comprising the steps of: (a) applying a photoresist on a surface of a substrate; (b) forming recording tracks by projecting light onto said photoresist; (c) developing said photoresist; (d) forming grooves by etching portions of said substrate which are not covered with said photoresist, the formation of said grooves being controlled so as to have a groove width in the range of 0.3 µm to 0.4 µm and a groove depth in the range of 80 nm to 100 nm; (e) removing said photoresist from said substrate; (f) forming a metallic layer on the surface of said substrate; and (g) peeling off said metallic layer from said substrate.
Claim 9
Dependent Claim
27 words
The manufacturing method according to claim 8, wherein step (d) is performed through a dry etching method using a gas containing a fluorine compound as a base.
Claim 10
Independent Claim
117 words
A method for manufacturing an optical memory substrate (1) having one or more tracks defined by alternating grooves (2) and lands (3) which extend in the track direction, the method comprising the step of forming said one or more tracks on said substrate using a metal stamper (14), the stamper having been manufactured by depositing metal (12, 13) on the surface of a substrate (8) which has been etched at portions (11) which correspond to the grooves (2) to be formed in the optical memory substrate (1), whereby reduction in the width of said lands (3) due to curvature where the land edge meets the groove wall is less than 0.2µm at each edge of the land.
References Cited (Backward Citations)
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