Hitachi, Ltd.

Other

Hitachi Maxell, Limited

Hitachi Maxwell, Ltd.

Hitachi Metals, Ltd.

Htiachi Ltd.

Hitachi, Ltd. and Hitachi Maxell, Ltd.

Hirofumi Sukeda

Harukazu Miyamoto

Hiroyuki Minemura

Motoyasu Terao

Tetsuo Andou

Hideki Saga

Takeshi Maeda

Masahiko Takahashi

Norio Ohta

Hidehiko Kando

Makoto Miyamoto

Toshio Niihara

Keiji Kataoka

Seiji Yonezawa

Toshiaki Tsuyoshi

Kouichirou Wakabayashi

Takehiko Yorozu

Takeshi Shimano

Hisataka Sugiyama

Hiroaki Nemoto

Shigeru Nakamura

Takuya Matsumoto

Atsushi Saito

Toshimitsu Kaku

Yohji Maruyama

Takehiko Hamaguchi

Masahiro Ojima

Hiroshi Ide

Takeshi Nakao

Hiroyuki Tsuchinaga

Kimio Nakamura

Hitoshi Watanabe

Akira Arimoto

Takahiro Kurokawa

Yoshito Tsunoda

Toshimichi Shintani

Fumiyoshi Kirino

Naoki Satoh

Kunikazu Ohnishi

Kensuke Ogawa

Masashi Kiguchi

Yoshinori Miyamura

Takashi Toyooka

Yasuhide Ouchi

Toshinori Sugiyama

Tsuneo Suganuma

Hiroshi Toyama

Masashi Suenaga

Keikichi Ando

Hiroshi Yasuoka

Tadao Ino

Tetsuo Ariyoshi

Tsuyoshi Miyai

Keizo Kato

Shinitsu Kinoshita

Kei Ishikawa

Tesuya Nishida

In an information recording/reproducing method performing a thermo-magnetic recording, a tracking offset value of a recording light spot and/or a tracking offset value of a magnetic flux detecting element is changed in accordance with a radial position at which a tracking is performed at the present time, to make a direction of a magnetic wall of a recording magnetic domain in accord with a longitudinal direction of the magnetic flux detecting element. Alternatively, a shape of a heated area is changed to be in accord with the direction of the magnetic flux detecting means at respective radial position, to make the direction of the magnetic wall of the recording magnetic domain in accord with the longitudinal direction of the magnetic flux detecting element.

Megneto-optical recording device capable of changing the shapes of heating areas

An information recording method using a recording medium includes forming a plurality of recording pulses in accordance with both a reference waveform having been stored in the recording medium and data regarding a shifting value relying on material of the recording medium also having been stored in the recording medium in a table manner, and recording information included in the plurality of recording pulses to the recording medium. The recording information is arranged to be stored according to the material of the recording medium.

Information recording method, information recording medium and information recording apparatus

Magneto-optical recording device capable of changing the shapes of heating areas

An information recording method using an optical recording medium including the steps of forming a plurality of recording pulses to irradiate the optical recording medium and recording information to the optical recording medium by irradiating the recording pulses on the optical recording medium. A leading edge of a first recording pulse of the recording pulses shifts at a shifting value, and the shifting value is determined by a combination of a length of M(n) of a mark being currently written and a length s(n&#x2212;1) of a space precedent to the mark.

An information recording apparatus using an optical recording medium includes a light source to irradiate a light beam to the optical recording medium and a pulse former for forming a plurality of recording pulses of the light beam. A leading edge of a first recording pulse of the recording pulses shifts at a shifting value, and the shifting value is determined by a combination of a length of M(n) of a mark being currently written and a length s(n&#x2212;1) of a space precedent to the mark.

An information recording method using an optical recording medium includes the steps of forming a plurality of recording pulses to irradiate the optical recording medium and recording information to the optical recording medium by irradiating the recording pulses on the optical recording medium. At least a leading edge of a first recording pulse and a trailing edge of a last recording pulse of the recording pulses shift at a shifting value, wherein the shifting value is determined by combinations of a length of M(n) of a mark being currently written and at least one of a length s(n&#x2212;1) of a space precedent to the mark and a length s(n+1) of a space subsequent to the mark.

In the past there has been a problem that on a detection surface the influence of interference causes a defocusing signal to degrade, narrowing the range in which spherical aberration can be stably detected. Accordingly, a diffraction grating is used to focus the inner and outer sides of luminous flux on separate optical detectors before the optical flux is focused on an optical detector and defocusing signals are independently calculated to find the difference therebetween, thereby providing a spherical aberration signal. This makes it possible to detect spherical aberration signals more stably.

Optical disk apparatus using mechanism for controlling spherical aberration

An optical reproducing apparatus that uses a hologram laser module and is applicable to a DVD Multi drive, wherein five sub spots of light in total that are most suitable to perform the differential push-pull tracking both for DVD-RAM and for DVD-R/RW are irradiated on the disk, respectively, and influence of several sub spots that are unnecessary in recording and reproducing a disk is canceled out by calculation, to realize an optical head that is compatible with the DVD Multi drive using a hologram laser module, and thereby providing a small-size, high-performance optical reproducing apparatus.

Optical reproducing apparatus

A recording apparatus for recording information to an optical recording medium having an aligned prepit portion straddled on a plurality of tracks in a radial direction, which prepit portion includes first and second prepit portions divided in a track direction. A prepit of the respective first and second prepit portions is arranged on a boundary of the respective tracks. The first prepit portion has an address information prepit and a synchronous information prepit and the second prepit portion has synchronous information prepit, the prepit of the first and second prepit portions being arranged at every two-track pitch in the radial direction and with one track displaced in the radial direction. The apparatus includes an irradiation source for irradiating a light spot on the optical recording medium, and a controller for controlling an irradiation position of an optical spot from the irradiation source.

Optical reproducing method for optical medium with aligned prepit portion

To generate a satisfactory recording magnetic domain on a recording medium and to improve the durability of a recording head, an information recording apparatus for generating an optical near field and thermo-magnetically recording information on the recording medium is provided with a light source, a magnetic pole for applying a magnetic field to the recording medium and a diffuser that generates an optical near field in the vicinity of the recording medium when light from the light source is radiated. The diffuser is formed with it in contact with the magnetic pole so that the face which light from the light source irradiates is substantially perpendicular to the recording medium. Thereby, recording density in the information recording apparatus can be increased, simultaneously the reliability can be also enhanced and as a result, the cost can be reduced.

Recording head and information recording apparatus

A recording method for an optical recording medium having an aligned prepit portion straddled on a plurality of tracks in a radial direction, wherein the prepit portion includes first and second prepit portions divided in a track direction. A prepit of the respective first and second prepit portions is arranged on a boundary of the respective tracks, the first prepit portion having an address information prepit and a synchronous information prepit and the second prepit having a synchronous information prepit. The prepits of the first and second portions are arranged at every two-track pitch in the radial direction and are arranged with one track displaced in the radial direction with a gap being provided between the first and second prepit portions. The method includes providing the optical medium, and recording information on the optical medium by irradiating an optical spot thereon.

A reproducing method for reproducing information from an optical recording medium having an aligned prepit portion straddled on a plurality of tracks in a radial direction, the prepit portion including first and second prepit portions divided in a track direction and arranged on a boundary line of the respective tracks. The first and second prepit portions each have address information prepits arranged at every two-track pitch in the radial direction, and the address information prepit of the first and second prepit portions are arranged with one track displaced in the radial direction. A trailing end of an end prepit of the first prepit portion is aligned with the radial direction. The method includes irradiating an optical spot on the medium, detecting a reflected beam from the medium, and reproducing information on the medium by using a signal obtained by the reflected beam.

A recording method for an optical recording medium having grooves and lands alternately provided in a radial direction and having information recording areas formed thereon, and at least one prepit region where a groove is not formed. In the prepit region, first and second information marks are disposed on a virtual extension of respectively a first boundary between one groove and one adjacent land and a second boundary between the one groove and an other adjacent land, the information marks being disposed so as not to exist at opposing positions on both of the first and second boundaries of the one groove. The first and second information marks include synchronous information and address information and a trailing edge of the first information marks is aligned in the radial direction. The method includes providing the optical medium, and recording information on the optical medium by irradiating an optical spot thereon.

Optical reproducing method optical medium with aligned prepit portion

A reproducing method for reproducing information recorded on an optical recording medium having an aligned prepit portion straddled on a plurality of tracks in a radial direction, the prepit portion including first and second prepit portions divided in a track direction and arranged on a boundary line of the respective tracks. The first and second prepit portions each have address information prepits arranged at every two-track pitch in the radial direction, and the address information prepit of the first and second prepit portions are arranged with one track displaced in the radial direction. The method includes irradiating an optical spot on the medium, detecting a reflected beam from the medium, and reproducing information on the medium by using a signal obtained by the reflected beam.

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Tokorozawa, Japan

Hirofumi Sukeda