Sony Corporation

Osamu Kawakubo

Toshiyuki Kashiwagi

Masahiko Kaneko

Koichi Yasuda

Ariyoshi Nakaoki

Kazuhiko Fujiie

Hitoshi Okada

Hideyoshi Horimai

Katsuhiro Seo

Motohiro Furuki

Naoya Eguchi

Yoshio Aoki

Akihiko Okubora

Naoto Kojima

Susumu Tosaka

Kazumine Ito

Koji Sekiguchi

Yutaka Kasami

Hiroshi Kawase

Mitsuo Naito

Tamotsu Maeda

Eiji Munemoto

Manami Nakamura

A signal detecting device includes: a semiconductor substrate; a near-field light generating section that is provided on the semiconductor substrate and generates near-field light near an interface with the semiconductor substrate; a light source that outputs light having wavelength corresponding to photon energy about a half as large as band-gap energy of a material of the semiconductor substrate; and a current detecting unit that detects a photocurrent generated in the semiconductor substrate when the near-field light is generated.

Signal detecting device and signal detecting method

Disclosed are an apparatus for initializing an optical recording medium to be initialized with stability and ease without employing any focus servo means, and a phase-changing optical recording medium initialized by the initializing apparatus to have a recording layer in a uniform crystalline state over an entire area of the medium which takes part in recording and reproduction of an information signal. In the apparatus for initializing a phase-changing optical recording medium, a laser beam emitted from a laser beam source is irradiated to a recording layer, in an amorphous state, formed in an optical recording medium to be initialized, which is a pre-stage member of the phase-changing optical recording medium, for changing the recording layer into a crystalline state. The laser beam source, e.g., a YAG laser, includes a high-speed shutter for exciting the laser beam source while the laser beam source is held in a state of not starting oscillation, and emits the laser beam within a very short time on the order of several tens nanoseconds (ns) to several hundreds nanoseconds (ns) with its peak power increased more than 10000 times that produced in a continuous oscillation mode.

Initializing a phase-changing optical recording medium using a laser including a high speed shutter

A phase change optical recording medium which enables optimum direct overwrite even under high speed high density conditions without degrading repetition durability or storage stability of recorded signals. To this end, the phase change optical recording medium has a recording layer formed at least of a phase change material and is recorded and/or reproduced with a laser light beam having a wavelength ranging between 380 nm and 420 nm. A ratio Ac/Aa, where Ac is the absorption rate of said recording layer in a crystalline state and Aa is the absorption rate of said recording layer in an amorphous state, is not less than 0.9, and a crystallization promoting layer promoting the crystallization of the phase change material is contacted with at least one surface of the recording layer. By exploiting the absorption rate control and the crystallization promotion in combination, it is possible to positively compensate the difference between the physical properties of the crystal phase and those of the amorphous phase to realize optimum direct overwrite.

Optical recording medium

Reduced thickness of a light transmissive layer for a high density optical disc

An optical recording medium according to the present invention includes a base layer having an information signal portion formed on a surface on the side on which laser light is incident, and a light transmissive layer formed on the base layer. A thickness t of the light transmissive layer is within the range of t=3 to 177 .mu.m at least in an area of the information signal portion. If unevenness of the light transmissive layer is .DELTA.t, N.A. of an optical system for reproduction or recording and reproduction and a wavelength .lambda. satisfies .DELTA.t.ltoreq..+-.5.26 (.lambda./N.A..sup.4) (.mu.m). A track pitch is P and a skew is .THETA., then P.ltoreq.0.64 .mu.m and .THETA..ltoreq..+-.84.115.degree. (.lambda./N.A..sup.3 /t) are satisfied. The optical recording medium is recorded or reproduced by a recording and reproducing system satisfying .lambda..ltoreq.0.68 .mu.m and N.A./.lambda..gtoreq.1.20. The optical recording medium permits a recording capacity of 8 GB.

Optical recording medium and optical disk apparatus

An optical recording medium is provided which achieves a higher recording capacity. This optical recording medium includes a base formed of thermoplastic resin which has a thickness ranging from between approximately 0.3 to 1.2 nm, a guide groove formed on the base, at least a reflective film and a phase-change recording layer successively formed on the guide groove, arid a light transmissive layer having a thickness ranging from between approximately 3 to 177 .mu.m. In this optical recording medium, the unevenness .DELTA.t of the thickness of the light transmission layer is set within the range of:

An optical recording medium having a phase-changing material layer served as a recording layer is composed to excellently repeat the rewrite of bits independently of the line speed of the writing light. The amount of the additive to be added to the phase-changing material layer is regulated in relation to the line speed for the write. The additive is added for suppressing the crystallization.

Phase-change optical recording medium having an additive related to the

A rotation control for a magnet used in a magneto-optical recording system having a first coil that rotates a permanent magnet to invert the polarity of its magnetic field applied to an optical recording type disc and a second coil provided at the position displaced from the central line of the first coil and for applying a driving force to the permanent magnet when the permanent magnet begins to rotate, wherein the permanent magnet can be settled in quite a short time after it is inverted in polarity by controlling a drive current applied to the second coil.

Device for controlling rotation of a magnet used in a magneto-optical

Disclosed is herein a magneto-optical recording system comprising: preparing a magneto-optical recording medium comprising a magneto-optical recording layer and a bias magnetic field formed on a transparent substrate, the magneto-optical recording layer having Curie temperature higher than room temperature, the bias magnetic layer having compensation temperature higher than Curie temperature, the magneto-optical recording layer and the bias magnetic layer being superposed having a nonmagnetic layer therebetween, and applying heating means to the magneto-optical recording medium having first and second heating power levels, the first heating power level being selected enough to heat the magneto-optical recording layer higher than the Curie temperature of the magneto-optical recording layer and to heat the bias magnetic layer higher than the compensation temperature of the bias magnetic layer, the second heating power level being selected enough to heat the magneto-optical recording layer higher than the Curie temperature of the magneto-optical recording layer while keeping the bias magnetic layer below the compensation temperature of the bias magnetic layer.

Magneto-optical recording system

The present invention discloses a method of producing a discharge display device which enables formation of a satisfactory LaB.sub.6 cathode without using a LaB.sub.6 paste containing a glass binder. The method of the present invention comprises the steps of applying a conductive paste containing a glass binder, temporarily drying said conductive paste to form a conductive paste layer, forming a LaB.sub.6 layer containing no glass binder on said conductive paste layer, burning said conductive paste layer and said LaB.sub.6 layer, at the same time, and activating said LaB.sub.6 layer after being burnt, and after an exhausting step by gas discharge with large current to form a LaB.sub.6 cathode.

Growing community of inventors

Saitama, Japan

Osamu Kawakubo