Kabushiki Kaisha Toshiba

Memory-tech Corporation

Nobuhisa Yoshida

Hideo Ando

Naomasa Nakamura

Hideki Ohkawa

Motonari Matsubara

Koji Takazawa

Hisashi Yamada

Katsumi Suzuki

Toshihiro Sugaya

Keiichiro Yusu

Sumio Ashida

Masato Otsuka

Kazuo Watabe

Yuji Nagai

Akihito Ogawa

Takayuki Tsukamoto

Yasuaki Ootera

Chosaku Noda

Naoki Morishita

Kazuyo Umezawa

Katsutaro Ichihara

Tsukasa Nakai

Kazuto Kuroda

Tomohisa Yoshimaru

Toshihiko Kaneshige

Hideaki Ohsawa

Hiroharu Sato

Noritake Ohmachi

Satoru Koyahara

Nobumasa Naito

According to one embodiment, a first encoder encodes main information, a second encoder encodes sub-information, a first modulator modulates a carrier based on an output of the first encoder, a duplicating module duplicates an output of the second encoder to generate encoded sub-information units, and a second modulator amplitude-modulates an output of the first modulator based on the encoded sub-information units. The second modulator amplitude-modulates with &#x3c3;/(&#x3bc;&#xd7;(2)) being 0.4 or less, wherein a noise power of a transmission path or a storage medium is &#x3c3;, a number of the encoded sub-information units is N, signal levels after amplitude modulation, which correspond to bitand bitof the encoded sub-information units, are A and B, and a level difference A&#x2212;B is &#x3bc;.

Signal processing system and information storage medium

The present invention relates to an optical recording media including two or more information layers, at least one of the information layers including a writable recording film. In the optical recording media, at least one information layer has protrusions and recesses that permit tracking and at least another one information layer is substantially flat.

Phase-change optical recording media and optical recording-reproducing apparatus

According to one embodiment, an optical disc is the following the distance between a light incidence plane and the first recording layer is a minimum of 550 &#x3bc;m. The distance between the first and the third recording layer is a maximum of 72 &#x3bc;m. The distance between the second and the third recording layer is a minimum of 15 &#x3bc;m. The distance between the first and the second recording layer is about 31 to 40 &#x3bc;m. The reflectivities of the first and the second recording layer with respect to the first laser beam range from 18 to 27%, and the ratio therebetween is about 1.1 or less. The reflectivity of the third recording layer is below about 6%. The areal recording density of the third recording layer is three times or more as high as that of the first recording layer and the second recording layer.

Optical disc, optical disc manufacturing method, and optical disc apparatus

An optical disc of this invention is configured to be capable of dealing with both information in HD DVD and information in DVD. The optical disc is basically specified by the following items (1) to (7): (1) the optical disc is a single-sided dual layer optical disc where a light transmission layer, a first recording layer accessed with a first laser beam, an space layer, and a second recording layer accessed with a second laser beam are arranged in that order in the direction in which the laser beam enters, (2) the areal recoding density of the second recording layer is three times or more as high as that of the first recording layer, (3) identifying information which indicates that the first recording layer has been formed is formed in the second recording layer, (4) the distance in the light transmission layer from the incidence plane to the first recording layer is 550 &#x3bc;m or more, (5) the distance in the light transmission layer from the incidence plane to the second recording layer is 622 &#x3bc;m or less, (6) the reflectivity of the first recording layer with respect to the first laser beam is 45% to 65%, and (7) the reflectivity of the second recording layer with respect to the second laser beam is 15% to 29%.

Optical disc, optical disc apparatus, optical disk reproducing method, and digital work publication

In an optical disk of the invention composed of two substrates bonded to each other, the level of double refraction is set to 60 nm or less in a read-only disk, to 60 nm or less in a write-once type disk, and to 40 nm or less in a rewritable type disk, respectively.

Optical disk and optical disk apparatus

A phase-change optical recording medium includes a phase-change optical recording film that permits reversible phase change between a crystalline phase and an amorphous phase upon irradiation with light, and an interface film formed of hafnium oxide, or a mixture of hafnium oxide and at least one oxide selected from the group consisting of cerium oxide, titanium oxide and zirconium oxide, and formed in contact with at least one surface of the phase-change optical recording film.

Phase-change optical recording medium

An optical recording medium of the present invention includes a light-transmitting substrate having spiral or concentric grooves formed in at least one major surface, a phase change recording film which is formed on the grooved surface of the substrate and reversibly changes phase upon irradiation of a light beam and thereby changes optical characteristics, and a reflecting layer formed on the phase change recording film, characterized in that the spiral or concentric grooves form, on at least one major surface of the substrate, lands and grooves as a rewrite region in which data is rewritten, the distance between the outer perimeter of the rewrite region and the center of the spiral or circle of the grooves is 58.5 mm or less, and the distance between the centers of a land and a groove adjacent to each other is 0.61 .mu.m to 0.62 .mu.m.

Optical recording medium

Optical recording medium and recording system

The present invention relates to an optical disk and a method of manufacturing the same, and, more particularly, to an optical disk which can ensure high-density recording and a method of pre-formatting this optical disk. This optical disk has a surface on which data is retrieved with a focused light beam and a light beam spot of a predetermined size is formed by the focused light beam, and comprises a first pit group having a plurality of unit pits of a unit pit length arranged in such a manner that adjoining unit pits are separated from each other with a blank of a first blank length, the blank being smaller than a size of the beam spot, the first blank length being set shorter than the unit pit length, and a second pit group following the first pit group and having a plurality of data pits whose lengths are substantially integer multiples of the unit pit length, the data pits being separated from one another with a blank of a second blank length.

Optical disk and method of manufacturing the same

The present invention provides an information recording medium including a first recording film formed on a substrate and having an amorphous phase made of an alloy containing at least Ge and Te, and a second recording film formed on the first recording film and made of a material with a relatively large light absorption coefficient, wherein the alloy of the first recording film exhibits a Raman scattering spectrum having scattering peaks at 140 to 160 cm.sup.-1 and 120 to 130 cm.sup.-1 and no scattering peaks at 100 to 110 cm.sup.-1, and recording is performed by changing optical characteristics by alloying the materials of the first and second recording films by radiating recording light on the first and second recording films. The present invention provides an information recording medium including a recording film formed on a substrate and having an amorphous phase made of an alloy containing Ge, Sb, and Te, wherein the amorphous phase of the recording film is a mixed phase containing cluster molecules containing of two elements, Ge--Te and/or Sb--Te, and recording is performed by changing optical characteristics by changing in phase the cluster molecules into corresponding crystalline GeTe and crystalline SbTe by radiating recording light on the recording film.

Information recording medium

Growing community of inventors

Kamakura, Japan

Nobuhisa Yoshida