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EP0745985A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Optical disk

Assignee: Victor Company of Japan Ltd
•
Filing: 1996-05-31
•
Granted: —
•
Expires: 2016-05-31
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Abstract

Abstract The present invention is an optical disk on which information which can be optically read is recorded and which is equipped with a first information recording layer, which is formed in the vicinity of the middle of the direction of the thickness of the disk, a second information recording layer, which is formed in the vicinity of the surface of the optical disk and which stores information at a lower density than the aforementioned first information recording layer, and a light incidence surface, into which the first and second playback laser beams, which are for reading the information in the first and second information recording layers are irradiated, and which is formed on the side opposite the surface, where, the thickness of the disk from the light incidence surface to the second information recording layer is made the same as the thickness of the disk from the light incidence surface on a single-substrate optical disk equipped with only a single information recording layer to the information recording layer, where, the diameter of the disk is made the same as the diameter of an optical disk with a single-substrate structure.

Inventors

  • 👤 Nishizawa Akira

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-11-09 21:50
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/26; G11B7/002; G11B7/0037; G11B7/2403; G11B7/24035; G11B7/24038; G11B7/2407; G11B7/24085

Claims Analysis

Total Claims: 5
Claim 1
Independent Claim 187 words
An optical disk in which information which can be optically read is stored, comprising: a first information recording layer formed in the vicinity of the middle of the thickness direction of the disk; a second information recording layer, which is formed in the vicinity of the surface of the aforementioned optical disk and which stores information at a lower density than the aforementioned first information recording layer; and a light incidence surface into which the first and second playback laser beams, which are for reading the information on the aforementioned first and second information recording layers, enter and which is formed at the side opposite the aforementioned surface; wherein, the thickness of the disk from the aforementioned light incidence surface to the aforementioned second information recording layer is made the same as the thickness of the disk from the light incidence surface, which is on the optical disk with a single-substrate structure equipped with only a single information recording layer, to the information recording layer, wherein, the diameter of the disk is made the same as the diameter of the aforementioned optical disk with a single-substrate structure.
Claim 2
Dependent Claim 55 words
The optical disk according to Claim 1, wherein the thickness of the disk from the aforementioned light incidence surface to the aforementioned second information recording layer is set to 1.1 to 1.3 mm, and the thickness of the aforementioned first information recording layer and second information recording layer is set to 0.5 mm or more.
Claim 3
Dependent Claim 16 words
The optical disk according to Claim 1, wherein at least two light-permeable substrates are bonded together.
Claim 4
Dependent Claim 68 words
The optical disk according to Claim 1, further comprising: a first substrate, which forms the aforementioned first information recording layer; and a second substrate, which forms the aforementioned second information recording layer; wherein the side where the first information recording layer of the aforementioned first substrate is formed and the side where the second information recording layer of the aforementioned second substrate is not formed are bonded together.
Claim 5
Dependent Claim 78 words
The optical disk of Claim 1, further comprising: a first substrate where the aforementioned first information recording layer and the aforementioned second information recording layer are not formed; and a second substrate, which forms the aforementioned first information recording layer on one side and forms the aforementioned second information recording layer on the other side; wherein the side where the first recording layer of the aforementioned second substrate is formed and the aforementioned first substrate are bonded together.

References Cited (Backward Citations)

JPH02223030A Cited

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