US 5,688,574 A · Optical recording medium

Abstract

Disclosed is a phase-change optical recording medium which has a reflectance and a signal modulation conformed to the CD standard, and which is usable for recording at the same linear velocity as the reproducing velocity specified in the CD standard. The phase-change optical recording medium comprises a metallic layer, a first protective layer, a recording layer, a second protective layer, and a reflecting layer on a substrate, in which recording is performed through change from a crystalline state to an amorphous state in the recording layer. The recording layer comprises a recording material of a Ge--Te--Sb--Se system, and the recording layer has an average composition in a direction of thickness which satisfies the following relations as represented by atomic %: Ge.gtoreq.40%, and Sb+Se.ltoreq.25% The recording medium has a reflectance of not less than 70% with respect to a light beam for reproduction when the recording layer is in one of the crystalline state and the amorphous state, and the recording medium has a reflectance of less than 40% when the recording layer is in the other state. An AuCo alloy is used as the metallic layer.

Claims24

Dependent claims

An optical recording medium comprising a metallic layer, a first protective layer, a recording layer, a second protective layer, and a reflecting layer on a substrate,

said recording medium being subjected to recording through change in atomic arrangement of the recording layer from a stable state to a metastable state, and said recording medium being subjected to initialization and erasing through change from the metastable state to the stable state, wherein:
said recording layer comprises a material containing major components of Ge, Te, Sb, and Se, and said recording layer has an average composition in a direction of thickness which satisfies the following relations as represented by atomic %:
Ge.gtoreq.40%, and Sb+Se.ltoreq.25%
said recording medium having a reflectance of not more than 40% with respect to a light beam for reproduction when the atomic arrangement of the recording layer is in the stable state, and said recording medium having a reflectance of not less than 70% with respect to the light beam for reproduction when the atomic arrangement of the recording layer is in the metastable state.

1 more element

An optical recording medium comprising a metallic layer, a first protective layer, a recording layer, a second protective layer, and a reflecting layer on a substrate, said recording medium being subjected to recording through change in atomic arrangement of the recording layer from a stable state to a metastable state, and said recording medium being subjected to initialization and erasing through change from the metastable state to the stable state, wherein:

said recording layer comprises a material containing major components of Ge, Te, Sb, and Se, and said recording layer has an average composition in a direction of thickness which satisfies the following relations as represented by atomic %:
Ge.gtoreq.40%, and Sb+Se.ltoreq.25%
said recording medium having a reflectance of not less than 70% with respect to a light beam for reproduction when the atomic arrangement of the recording layer is in the stable state, and said recording medium having a reflectance of not more than 40% with respect to the light beam for reproduction when the atomic arrangement of the recording layer is in the metastable state.

Dependencies are inferred from the claim text.

Optical recording medium

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Optical recording medium

Life of this patent

Abstract

Claims24