Sony Corporation

Fuminori Takase

Toru Abiko

Minoru Kikuchi

Yoshihiro Akimoto

Nobuhiro Saito

Etsuro Ikeda

Hitoshi Shimomuki

Yuichi Sabi

Masatsugu Suwabe

Masaki Kagawa

Noriko Kikuchi

Nobuaki Furuichi

A recording medium is provided and includes; a substrate having a first area formed with a first groove and a second area formed with a second groove, at least one information layer provided on the substrate, and a protecting layer provided on the information layer. Predetermined binary information has previously been recorded on the first groove and the first groove is shallower or narrower than the second groove.

Recording medium, its manufacturing method, mother disc for recording medium, and its manufacturing method

To accomplish write-once type optical recording mediums that have excellent recording and reproducing characteristics and producibility and that are capable of being fabricated at low cost. A write-once type optical recording mediumhas the structure of which an inorganic recording film, a dielectric film, and a light transmission layerhave been successively formed on a substrate. The inorganic recording filmis composed of a metal filmand an oxide filmsuccessively formed on the substrate. When light is radiated to the inorganic recording film, oxygen is separated from the oxide filmdue to the light catalyst effect, resulting in increasing the oxygen concentration on the metal filmside and largely varying the optical constant.

Write-once type optical recording medium and fabrication method thereof

In an optical recording mediumhaving a configuration in which on one main surface of a substrate, a reflective layer, a lower dielectrics layer, a recording layer, an upper dielectrics layerand a light transmissive layerare sequentially laminated, the lower dielectrics layeris formed of a first lower dielectrics layer and a second lower dielectrics layer that inhibits a material that constitutes the first lower dielectrics layer and a material that constitutes the reflective layerfrom reacting, and the upper dielectrics layeris formed of a first upper dielectrics layer and a second upper dielectrics layer that inhibits a material that constitutes the first upper dielectrics layer and a material that constitutes the light transmissive layerfrom reacting.

Optical recording medium and method for manufacturing same

In order to ensure CAV recording/reproduction while preventing jitter deterioration and modulation decrease and thereby ensuring sufficient recording properties, even at a linear velocity higher than 4.8 m/s, a first dielectric film, phase change versatile recording film, second dielectric film, reflection film and protective film are formed on a disc substrate having formed lands and grooves on one major surface. The recording film is made of a GeInSbTe alloy, and the reflection film is made of an AgPdCu alloy or AlCu alloy. Composition of the GeInSbTe alloy is adjusted to contain Ge in the range of 1 to 6 wt %, In in the range of 2 to 6 wt %, and control Sb/Te in the range of 2.2 to 3.0. Composition of the AgPdCu alloy is adjusted to contain Cu not more than 1.5 wt %. Regarding groove conditions, groove depth is controlled in the range of 40 to 50 nm, groove width in the range of 0.40 to 0.65 &mgr;m, thickness of the first dielectric film in the range of 75 to 95 nm, thickness of the recording film in the range of 12 to 18 nm, thickness of the second dielectric film in the range of 20 to 28 nm, and thickness of the reflection film in the range of 60 to 140 nm.

Optical recording medium

In order to increase the recording capacity while preventing jitter deterioration and a decrease of the modulation factor and thereby ensuring satisfactory recording characteristics, a first dielectric film, phase recording film, second dielectric film, reflection film and protective film are sequentially formed on a disc substrate having formed lands, grooves and wobbling on one major surface. The recording film is made of a GeInSbTe alloy, and the reflection film is made of an AgPdCu alloy or AlCu alloy. Composition of the GeInSbTe alloy is adjusted to contain Ge in the range of 1 to 8 wt %, In in the range of 2 to 6 wt %, and control Sb/Te in the range of 2.2 to 3.0. Composition of the AgPdCu alloy is adjusted to contain Pd in the range of 0.9 to 1.5 wt % and Cu not more than 1.5 wt %. Composition of the AlCu alloy is adjusted to contain Cu in the not more than 1.5 wt %. Groove depth is controlled in the range of 35 to 45 nm, groove width in the range of 0.35 to 0.50 &mgr;m, thickness of the first dielectric film in the range of 75 to 95 nm, thickness of the recording film in the range of 12 to 20 nm, thickness of the second dielectric film in the range of 16 to 28 nm, and thickness of the reflection film in the range of 80 to 160 nm.

Optical disc having specified track pitch, push-pull signal, and cross-track signal

Optical Disc

A phase-change optical disc has a recording layer formed from a phase-change material switchable between a crystalline state and an amorphous state. The recording layer is illuminated signal-wise by a light is focused onto the recording layer to change the phase thereof from crystalline to amorphous, to thereby write an information signal onto the recording layer. The phase-change material contains a GeSbTe alloy. The recording layer is formed by sputtering in an Ar gas atmosphere containing at least either N,or O,gas or both. The optical recording medium exhibits improved durability after repeated recording and maintains a stable and good write/read characteristic even after repeated cycles of signal recording.

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Miyagi, Japan

Fuminori Takase