Sony Corporation

Sony Disc & Digital Solutions Inc.

Takahiro Igari

Sohmei Endoh

Takeshi Gouko

Noriyuki Saito

Shinji Minegishi

Eijiro Kikuno

Hiroshi Nakayama

Makoto Watanabe

Tadao Suzuki

Hiroyuki Takemoto

Katsuhiko Ohtomo

Masatsugu Suwabe

Teruyuki Ota

Yuko Asano

An optical recording medium includes a recording layer including a reflective layer, two dielectric layers, and a phase-change recording layer. The phase-change recording layer-side dielectric layer of the two dielectric layers contains tantalum oxide or a composite oxide composed of silicon oxide, indium oxide, and zirconium oxide. The reflective layer-side dielectric layer of the two dielectric layers contains a composite oxide composed of silicon oxide, indium oxide, and zirconium oxide, a composite oxide composed of indium oxide and gallium oxide, or a composite oxide composed of zinc oxide and aluminum oxide.

Optical recording medium

An optical recording medium includes: a substrate having a first principal surface and a second principal surface; one or plural information signal layers formed on the first principal surface of the substrate for undergoing recording or reproduction of information signals upon irradiation with light; and a barrier layer formed on the second principal surface of the substrate for suppressing the gas release from the second principal surface of the substrate, wherein an area of a region exposing from the barrier layer of the second principal surface of the substrate is not more than 688 mm.

Optical recording medium and method for manufacturing the same

An optical recording medium includes: a substrate; an information signal layer provided on the substrate; and a protective layer provided on the information signal layer. The information signal layer is provided with a reflecting layer, a recording layer provided on the reflecting layer and first, second and third dielectric layers laminated successively on the recording layer. Refractive indexes of the first, second and third dielectric layers are different from each other between the adjacent dielectric layers to each other. Among the first, second and third dielectric layers, the dielectric layer having the highest refractive index contains, as a main component, at least one member selected from the group consisting of titanium oxide, niobium oxide and a mixture of zinc sulfide and silicon oxide. The dielectric layer having the highest refractive index has a refractive index of 2.3 or more at a wavelength of 405 nm.

Binary information previously recorded in an innermost rim side area is enabled to be stably reproduced. A record medium is formed by sequentially laminating a first information layer, an intermediate layer, a second information layer, and a cover layeronto a substrate. First grooves are previously formed in the innermost rim area of the substrate. Second grooves are previously formed in an area where data is recorded. The first grooves are set to be shallower and narrower than the second grooves. Thus, such a situation that a BCA signal is modulated by diffraction due to the grooves can be reduced.

Record medium, its manufacturing method, mother disc for record medium, and its manufacturing method

A recording method whereby an inorganic resist made of an incomplete oxide of a transition metal is formed as a film onto a substrate and a latent image corresponding to pits is formed onto the inorganic resist by exposure. The exposure is performed by a laser beam whose intensity has been modulated by a pulse signal whose pulse height decreases in a rear portion in a length direction of the pit, thereby forming a format of a track pitch smaller than a recording beam diameter (track pitch/exposure beam diameter=0.333 to 0.833).

Systems and methods for forming a master disk utilizing variation in an applied signal power for forming uniform pits

High density optical disc having small track pitch

Method for making an optical disc having a track pitch smaller than a recording beam diameter

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Miyagi, Japan

Takahiro Igari