Hitachi, Ltd.

Hitachi Maxell, Limited

Hitachi Metals, Ltd.

Inphase Technologies, Inc.

Nippon Columbia Co., Ltd.

Masahiko Takahashi

Norio Ohta

Harukazu Miyamoto

Hirofumi Sukeda

Toshio Niihara

Keiji Kataoka

Seiji Yonezawa

Toshiaki Tsuyoshi

Fumiyoshi Kirino

Shigeru Nakamura

Kimio Tatsuno

Takeshi Maeda

Motoyasu Terao

Hisataka Sugiyama

Yoshio Suzuki

Kazuo Shigematsu

Hideki Saga

Yumiko Anzai

Yohji Maruyama

Takehiko Hamaguchi

Hiroshi Ide

Shinji Fujita

Yoshinori Miyamura

Hiroaki Nemoto

Kimio Nakamura

Yasushi Fukuda

Shigenori Okamine

Ryo Suzuki

Kevin R Curtis

Takeshi Shimano

Akira Arimoto

Toshimitsu Kaku

Masaaki Futamoto

Kenchi Ito

Yasushi Miyauchi

Tetsuya Nishida

Yoshito Tsunoda

Kenichi Shimada

Tetsuo Andou

Masahiro Ojima

Keikichi Andoo

Takeshi Nakao

Tatsuro Ide

Takashi Toyooka

Fumio Kugiya

Tsuneo Suganuma

Ken E Anderson

Reiji Tamura

Tsuyoshi Miyai

Koji Muraoka

Kazuhiko Nakano

Noriyuki Ogihara

Norio Murase

Manabu Sasaki

Sten Helmfrid

Junko Nakamura

Hisae Sasaki

An optical disc recording method of suppressing variations in the record quality due to variations in an initial strategy of a write strategy using many parameters corresponding to a next-generation large-capacity optical disc. Modulation conditions for recorded data on the optical disc are determined based on a real measurement thereof; an initial strategy that meets the modulation conditions is determined; an optical strategy is determined in which the record quality is best in the vicinity of the initial strategy; and data is recorded on the optical disc, using the optimal strategy.

Write strategy determining method, optical disc recording method, optical disc and optical disc apparatus

An optical pickup for recording a hologram by using an angle multiplexing method. An optical beam is separated into two beams, a signal beam and a reference beam having different convergence/divergence degrees, by using an optical component such as a diffraction lens. The signal and reference beams are made incident upon the same objective, and the optical component or the objective lens is moved in a direction perpendicular to an optical axis, to thereby realize angle multiplex recording. If an optical information recording medium is inclined, the optical component or the objective lens is moved along the direction along which the optical information recording medium moved to change an angle of the reference beam incident upon the optical information recording medium and compensate for degradation of a reproduction signal.

Optical pickup, optical information recording and reproducing apparatus and method for optically recording and reproducing information

In an apparatus and method for information storage and retrieval, information is retrieved from the storage apparatus in a manner which includes varying an operational parameter of the storage apparatus according to a property of the information being retrieved. In the same apparatus and method, information is stored onto the storage apparatus in a manner which includes varying an operational parameter of the storage apparatus according to a property of the information to be stored. In this way, the energy consumption of the storage apparatus can be kept low.

Method and apparatus for reading and writing information onto and from information recording disks

A method for reproducing information on a recording medium includes irradiating electromagnetic energy or light to the recording medium from one side with respect to the recording medium, applying a recording magnetic field to an electromagnetic energy or light irradiated position on the recording medium from the one side of irradiating electromagnetic energy or light, and detecting magnetic leakage flux emerging from the recording medium from the one side of irradiating electromagnetic energy or light.

Method for reproducing information on a recording medium

An information recording apparatus using a recording medium which holds information by reversed magnetic domains on a perpendicular magnetic recording film includes an irradiation unit for applying electromagnetic energy or light onto the recording medium, and a magnetic flux detection unit for detecting magnetic leakage flux emerging from the recording medium, the magnetic flux detection unit being disposed on the same side as the irradiation unit with respect to the recording medium. As a result, both side recording of the recording medium can be conducted.

Information recording/reproducing device

A data recording and reproducing apparatus includes a recording disabled state determining device for determining whether or not the optical disc is in a recording disabled state, in which the data recording and reproducing apparatus controls the rotation of the optical disc to increase a rotational speed during reproduction processing higher than the rotational speed during recording processing to reproduce data when the recording disabled state determining device determines that the optical disc is in the recording disabled state, thereby accepting a recording instruction and a reproduction instruction as required at any time, and avoids reproducing data at the same reproducing speed as a recording speed which is unnecessarily slower than the reproducing speed.

Apparatus for recording and reproducing data

A magneto-optical data recording system comprises magnetic field pulse applying means for applying to a magneto-optic recording medium a magnetic field pulse of a polarity corresponding to code data to be recorded, and means for heating the recording medium in a pulsating manner at a predetermined frequency synchronous with the code data to be recorded. During recording, the magnetic field pulse applying means applies a magnetic field pulse of a polarity corresponding to code data along a track of the recording medium and the heating means continuously heats the recording medium in a pulsating manner at a predetermined frequency synchronous with the code data to thereby directly overwrite the code data. The magnetic field pulse applying means includes a magnetic coil driven by code data from a source of code data (data generator). The heating means includes an optical head which comprises a source of laser beam driven by a laser driver and an optical system which focuses the laser beam from the source of laser beam as a small light spot onto the recording medium.

Information recording medium with clock information therein

Information recording apparatus and method for modulated magneto-optical

A multilayer optical information medium provided with structure in which first and second substrates respectively provided with two to four layers of planar information areas are respectively arranged outside wherein the thickness of the above-described first and second substrates is set in the range of 0.52 to 0.65 mm. The above-described planar information area consists of embossed pits provided, for example on the surface of respective substrates or on the surface of a layer formed by transparent material and a semi-reflective layer provided on the embossed pits. A planar information area arranged in the farthest position from respective substrates is provided with a reflective layer in place of the above-described semi-reflective layer. The planar information area arranged in the farthest position from respective substrates may be constituted by a recording layer and a reflective layer provided on the recording layer.

Multilayer optical information medium

A magneto-optical recording medium comprises in combination: a magneto-optical recording layer capable of writing or erasing information by a laser beam and an external magnetic field and of reading the information by a Kerr effect; and a substrate having the magneto-optical recording layer formed thereon. The magneto-optical recording layer has at least two layers, including a first magneto-optical recording layer and a second magneto-optical recording layer which are magnetically coupled together. The first magneto-optical recording layer is a layer providing a greater magneto-optical effect in a short light wavelength range than the second magneto-optical recording layer though that having less perpendicular magnetic energy than this, as is provided on an irradiation side of the laser beam. It provides advantages in both the magneto-optical effect and perpendicular anisotropy in consideration of the thicknesses or compositions of the first and second magneto-optical recording layers.

Magneto-optical recording medium and method

Magneto optical recording medium apparatus and method utilizing light

In a magneto-optical disk for recording, reproduction or erasing with a laser beam, which comprises a film of four-layer structure consisting of a first dielectric layer, a magneto-optical recording layer, a second dielectric layer and a metallic layer, laid on a disk substrate provided with guide tracks, temperature distribution of the magneto-optical recording layer is controlled by controlling the thermal diffusivity of the metallic layer, and recording/reproduction/erasing repetition characteristics are improved thereby. In the disk of the present structure, the temperature is elevated in a broader area from the center of laser beam, and thus a thoroughly broad erasing domain width taking a track offset into account can be obtained and no recording domains remain after the erasing. The reproduced signal output is increased by 4 dB, as compared with that obtained by a disk of three-layer structure without any metallic layer, because the beam utilization efficiency is increased owing to both Kerr effect and Faraday effect. When the disk of the present structure is subjected to field modulation recording, tails of arrow-feather-shaped recording domains peculiar to the field modulation recording can be shortened and interbit interferences can be overcome, resulting in an increase in C/N (S/N) ratio and the high density recording can be made.

Magneto-optical disk

A recording mark having width (disk radius direction) larger than length (disk rotation direction) is formed by using the light intensity modulation method. The recording mark is ring-shaped. The ring part differs in optical characteristic from a part surrounded by the ring part. In order to form a ring-shaped mark, laser light having predetermined intensity is continuously radiated onto the recording medium. By modulating the intensity of the laser light, information is overwritten. The ring-shaped mark is set to have a width based upon the intensity of radiated laser light and the characteristic of the recording film.

Overwritable optical recording medium and recording method of the same

A magneto-optical data recording system comprises magnetic field pulse applying apparatus for applying to a magneto-optic recording medium a magnetic field pulse of a polarity corresponding to code data to be recorded, and apparatus for heating the recording medium in a pulsating manner at a predetermined frequency synchronous with the code data to be recorded. During recording, the magnetic field pulse applying apparatus applies a magnetic field pulse of a polarity corresponding to code data along a track of the recording medium and the heating apparatus continuously heats the recording medium in a pulsating manner at a predetermined frequency synchronous with the code data to thereby directly overwrite the code data. The magnetic field pulse applying apparatus includes a magnetic coil driven by code data from a source of code data (data generator). The heating apparatus includes an optical head which comprises a source of laser beam driven by a laser driver and an optical system which focuses the laser beam from the source of laser beam as a small light spot onto the recording medium.

Magneto-optical data recording apparatus using a sample-servo system for

Growing community of inventors

Hachioji, Japan

Masahiko Takahashi