Fujitsu Corporation

Miyozo Maeda

Ken-ichi Itoh

Kenichi Utsumi

Nagaaki Koshino

Akira Ushioda

Yasuyuki Goto

Itaru Shibata

Kozo Sueishi

Koji Matsumoto

Yasunobu Hashimoto

Seiya Ogawa

Haruhiko Izumi

Ken Tamanoi

Toshio Sugimoto

Mineo Moribe

Motonobu Mihara

Masaharu Moritsugu

Kyoko Miyabe

Yuji Inouye

Susumu Satoh

Shigenori Yanagi

Tsutomu Tanaka

Toru Ikeda

Kazuo Nakashima

Keiji Shono

Yoshiyuki Nanba

Takehiko Numata

Yoshiyuki Namba

A storage apparatus has a function of controlling rotation of a recording medium which is divided into a plurality of zones in a radial direction thereof and employing a ZCAV system. The storage apparatus is provided with a setting part for setting a mode to one of a normal mode in which the recording medium is controlled to rotate at a first rotational speed, and a high-speed mode in which the recording medium is controlled to rotated at a plurality of second rotational speeds respectively corresponding to a plurality of areas to which the recording medium is divided in the radial direction thereof.

Rotation control method for controlling rotation of media having zones in radial direction and employing ZCAV system, and storage apparatus using the rotation control method

A magneto-optical recording medium adapted for reproduction of a high resolution signal without the necessity of a reproducing magnetic field. The magneto-optical recording medium comprises a transparent substrate and deposits of a reproducing layer, a switch layer and a recording layer formed on the transparent substrate successively. The reproducing layer is a perpendicular magnetization film at a room temperature but is turned to an in-plane magnetization film when heated beyond a predetermined temperature. Each of the switch layer and the recording layer is a perpendicular magnetization film. The respective Curie temperatures Tc1, Tc2 and Tc3 of the reproducing layer, the switch layer and the recording layer satisfy the relationship of Tc1&gt;Tc3&gt;Tc2. When a reproducing laser beam is irradiated to the recording medium, the switched connection between the reproducing layer and the recording layer is interrupted in a high temperature region heated beyond the Curie temperature of the switch layer, whereby the reproducing layer is caused to present in-plane magnetization.

Magneto-optical recording medium and method of reproducing information

An optical disk is made up of a disk-shaped substrate having a surface, a first track and a second track provided on the surface of the substrate, where the first and second tracks are two mutually adjacent concentric tracks or two mutually adjacent track turns of a single spiral track, the first track extends along a first center line and the second track extends along a second center line, and an identification signal recording part extending along a third center line and prerecorded with an identification signal including at least a sector number and a track number for identifying a position on the optical disk. The third center line is arranged between the first and second center lines, and the identification signal prerecorded in the identification signal recording part is common to the first and second tracks on both sides of the identification signal recording part.

Optical disk having identification signal recorded between and used in

Marks are recorded on an optical disk which is rotated at a constant rotational speed by laser light which is converged on a substantially circular spot. The pulse width of a recording pulse is set at a sufficiently narrow value and the recording power of the laser light is maintained at a constant value. Marks (corresponding to '1') are recorded on the entire disk surface by the laser light with the same recording pulse width and with the same recording power. The recording pulse width is less than about 30% of the mark interval obtained when they are recorded on the optical disk at the highest density. The recording power is set at the value which produces the maximum reproduction amplitude when said marks are recorded on the optical disk at the highest density.

Optical disk apparatus

Disclosed is a magneto-optical recording medium adapted for reproduction of a high resolution signal without the necessity of a reproducing magnetic field, whereby the magneto-optical recording medium comprises a transparent substrate, a reproducing layer, a switch layer and a recording layer formed on the transparent substrate successively. The reproducing layer is a perpendicular magnetization film at a room temperature but is turned to an in-plane magnetization film when heated beyond a predetermined temperature. Each of the switch layer and the recording layer is a perpendicular magnetization film. The respective Curie temperatures Tc1, Tc2 and Tc3 of the reproducing layer, the switch layer and the recording layer satisfy the relationship of Tc1&gt;Tc3&gt;Tc2.

An optical disk is adapted for use in an optical disk unit which irradiates a light beam spot on a target track on the optical disk and controls tracking of the light beam spot based on a tracking error signal which is generated based on a reflected light beam from the optical disk. The optical disk includes a disk shaped substrate, a spiral or concentric guide tracks provided on the substrate, a writable region provided on the substrate between two mutually adjacent track turns of the guide track, and a preformed track provided within the guide track and prerecorded with read-only information in a form of variations of a topological feature. The guide track and the topological feature have mutually different height positions so that a tracking error signal which is generated when the light beam spot scans the guide track has the same amplitude as a tracking error signal which is generated when the light beam spot scans the preformed track, and the height positions of the guide track and the topological feature are different from a height position which generates a maximum tracking error signal amplitude when scanned by the light beam spot.

Constant amplitude of tracking error signals generated from a head guide

A process for recording information on a magneto-optical recording medium according to a (2, 7) RLL modulated signal includes a step of setting an optical power of a laser beam to a high level state in response to a logic value '1' and a step of alternately switching the optical power of the laser beam between the high level state and a low level state in correspondence to a logic value '0' except for the bit that is immediately adjacent to the bit of the logic value '1.'

Magneto-optical recording method and apparatus for recording information

A method for overwriting information in a magneto-optical memory medium which includes a simultaneous writing and erasing step of continuously irradiating a written information-carrying area of the recording layer of the memory medium with two different pulses from a single laser beam head in accordance with information to be written, regardless of the presence or absence of written information. A variation includes irradiating the written information-carrying area with an erasing pulse from a laser beam head, regardless of the presence or absence of written information, and then selectively irradiating the information-erased area with a writing pulse from another laser beam head in accordance with information to be written. According to these methods, it becomes possible to carry out a simple and high-speed overwriting with an increased and stabilized bit positioning accuracy.

Magneto optical overwriting methods using a single optical head designed

A disk storage device includes a light source emitting a light, an objective lens for focusing the light on a surface of a recording film of a disk via a protection film protecting the recording film, and a motor for rotating the disk. A detector receives the light reflected by the surface of the recording film and reproduces information recorded on the recording film. The detector is located at a position where the following condition is satisfied:

Disk storage device having light receiving device located at improved

An optical disk provided with read-exclusive regions where previously recorded information can be read, and with write-enable regions where information can be written. Information not desired to be rewritten can be recorded on the read-exclusive regions. The write-enable regions are open to users to freely add information thereto and to re-write information recorded. This optical disk can thus be used in various fields.

Optical disk having read-exclusive and write-enable regions

A method of overwriting information in a magneto-optical memory medium which includes a simultaneous writing and erasing step of continuously irradiating a written information-carrying area of the recording layer of the memory medium with two different pulses from a single laser beam head in accordance with information to be written, regardless of the presence or absence of written information. A variation includes irradiating the written information-carrying area with an erasing pulse from a laser beam head, regardless of the presence or absence of written information, and the then selectively irradiating the information-erased area with a writing pulse from another laser beam head in accordance with information to be written. According to these methods, it becomes possible to carry out a simple and high-speed overwriting with an increased and stabilized bit positioning accuracy.

Magneto-optical overwriting methods using erasing pulses, each of which

Recording and erasing optical information can be done by using an alloy film capable of forming two stable crystalline states differing in crystal texture and optical characteristics by being irradiated with optical energies under different conditions. A thin memory film preferably including 60 to 90 atom % of Indium (IN) and 10 to 40 atom % of Bismuth (Bi) is formed on a substrate.

Optical information memory medium including indium (In) and bismuth (Bi)

Recording and erasing optical information can be done by using an alloy film capable of forming two stable crystalline states differing in crystal texture and optical characteristics by being irradiated with optical energies under different conditions. The thin memory film preferably includes not more than 60 atom % of Gallium (Ga) and not less than 40 atom % of Antimony (Sb).

Optical information memory medium recording and erasing information

Recording and erasing optical information can be done by using an alloy film capable of forming two stable crystalline states differing in crystal texture and optical characteristics by being irradiated with optical energies under different conditions. The memory film includes 35-45 atom % of indium (In) and 55-65 atom % of antimony (Sb). The memory film may include an additional element M selected from the group consisting of Al, Si, P, S, Zn, Ga, Ge, As, Se, Ag, Cd, Sn, Te, Tl, Pb, Bi, and a combination of these elements, the composition of the memory film being expressed by the formula (In.sub.x Sb.sub.1-x).sub.1-y M.sub.y.

Method for recording information in an optical information memory medium

Recording and erasing optical information can be done by using an alloy film capable of forming two stable crystalline states differing in crystal texture and optical characteristics by being irradiated with optical energies under different conditions. The memory film includes 35-45 atom % of Indium (In) and 55-65 atom % of antimony (Sb).

Growing community of inventors

Kawasaki, Japan

Miyozo Maeda