EP0352105A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Optical disc medium
Assignee: Fujitsu Ltd
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Filing: 1989-07-20
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Granted: —
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Expires: 2009-07-20
Abstract
Abstract An erasable optical disc medium on which information is recorded and read by using a laser beam, which comprises (i) a phase transition type information recording layer (2), (ii) an optical interference layer (3) and (iii) an optical reflection layer (4), formed in this order on a transparent substrate (1), in such a state that a reflectance of the medium is higher before information is recorded and a reflectance of the recorded portions of the medium is lower after recording. The erasable optical disc medium may be used in place of a standard CD medium, e.g. in a CD-ROM drive.
Inventors
- 👤 Yasuyuki Goto
- 👤 Nagaaki Koshino
- 👤 Kenichi Utsumi
- 👤 Iwao Tsugawa
- 👤 Masahiro Nakada
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 10:29
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/24; G11B7/241; G11B7/242; G11B7/243; G11B7/2433; G11B7/004; G11B7/0055; G11B7/00557
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
77 words
An erasable optical disc medium on which information is recorded and read by using a laser beam, said medium comprising (i) a phase transition type information recording layer, (ii) an optical interference layer and (iii) an optical reflection layer, formed in this order on a transparent substrate in such a state that a reflectance of the medium is higher before information is recorded and a reflectance of the recorded portions of the medium is lower after recording.
Claim 2
Dependent Claim
77 words
An erasable optical disc medium on which information is recorded and read by using a laser beam, said medium comprising (i) a phase transition type information recording layer, (ii) an optical interference layer and (iii) an optical reflection layer, formed in this order on a transparent substrate in such a state that a reflectance of the medium is higher before information is recorded and a reflectance of the recorded portions of the medium is lower after recording.
Claim 3
Dependent Claim
32 words
An optical disc medium as claimed in claim 1, wherein the information recording layer is a phase transition type thin film layer, a crystal state of which is changed by laser irradiation.
Claim 4
Dependent Claim
25 words
An optical disc medium as claimed in claim 1 or 2, wherein the information recording layer is mainly composed of a crystalline-to-crystalline phase transition material.
Claim 5
Dependent Claim
33 words
An optical disc medium as claimed in claim 1, 2 or 3, wherein the information recording layer is composed of a thin film having a film thickness of from 5 to 20 nm.
Claim 6
Dependent Claim
31 words
An optical disc medium as claimed in claim 1, wherein the information recording layer is mainly composed of In-Sb, Te-Ge, or an alloy containing as a main constituent In-Sb or Te-Ge.
Claim 7
Dependent Claim
35 words
An optical disc medium as claimed in any preceding claim, wherein the optical interference layer in an inorganic thin film layer or an organic thin film layer which is transparent at the film thickness used.
Claim 8
Dependent Claim
42 words
An optical disc medium as claimed in any preceding claim, wherein the optical reflection layer has a reflectance of at least 70% and the difference in the reflectance of the recorded portions before and after information is recorded is at least 20%.
Claim 9
Dependent Claim
40 words
An optical disc medium as claimed in any preceding claim, wherein the thickness d (nm) of the optical interference layer is wherein ñ is a refractive index of an interference layer material and N is 0 or a positive integer.
Claim 10
Dependent Claim
27 words
An optical disc medium as claimed in any preceding claim, wherein the optical interference layer is composed, as a main component, of ZnS, SiO₂, MgF₂, or MgO.
Claim 11
Dependent Claim
36 words
An optical disc medium as claimed in any of claims 1 to 8, wherein the optical interference layer is composed, as a main component, of silicone resin, stearic acid type salt, phthalocyanine, or silylated polymethyl silsesquioxane.
Claim 12
Dependent Claim
22 words
An optical disc medium as claimed in any preceding claim, wherein the optical reflection layer has a reflectance of at least 70%.
Claim 13
Dependent Claim
28 words
An optical disc medium as claimed in any preceding claim, wherein the optical reflection layer is a metallic thin film mainly composed of Au, Ag, Cu, or Al.
References Cited (Backward Citations)
No citation records indexed.
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