Hitachi, Ltd.

Hiroshi Yasuoka

Motoyasu Terao

Tetsuya Nishida

Keikichi Andoo

Norio Ohta

Yoshito Tsunoda

Masahiro Ojima

Takeshi Maeda

Shigeru Nakamura

Hirofumi Sukeda

Toshimitsu Kaku

Seiichi Mita

Yasushi Miyauchi

Hiromichi Fujisawa

Yoshihisa Kamo

Shunichi Torii

Kunikazu Ohnishi

Takeshi Nakao

Yoshinori Miyamura

Kiyoshi Matsumoto

Yoshihiro Hamakawa

Masuo Kasai

Keikichi Ando

Eiichi Seya

Zenji Tsutsumi

Norio Murase

Tesuya Nishida

A fast access high capacity data storage system and method are disclosed, the data storage system including a disk-based storage system employing a plurality of storage surfaces. Selected storage surfaces have a plurality of independently controlled data access heads in data communication therewith, and circuitry is provided for allowing concurrent data transfers through the plurality of data access heads. Performance is further improved by monitoring frequently accessed data records and transferring them to a copy recording surface or recording surfaces less frequently used, and by moving a data access head of the plurality of data access heads to other recording surfaces to decrease access bottlenecks. The storage system further includes circuitry for averaging at least one of record length data, transfer timing data, access timing data and address data.

High capacity data storage method and system using independently

According to the present invention, a so-called overwrite operation which records new information while erasing existing information can be reliably performed in an information storage system such as optical disk system. In addition, whether the rewriting of recording has been properly done can be verified.

Method for recording and reproducing information using at least two

A method of recording information by changing a recording medium through irradiation with an energy beam such as a light beam, electron beam or the like. A single pulse or a plurality of pulses are employed for forming recorded dots. The pulse has a pulse width shorter than a time required for the center of energy beam spot to move from one to other end of the dot upon recording thereof. By virtue of the possibility of reversible change even in a recording film susceptible to high rate speed of change, the rate of information transfer can be increased. Over-write recording can also be accomplished with the single laser beam. An increased amount of information can be handled in the recording and reproduction.

Recording waveform for mark-length modulation optical recording

A separation type optical head according to the present invention includes at least a light source portion for emitting collimated beams, a focusing device (a focusing lens) for focusing the collimated beams onto an information recording surface of an optical disc medium, a focal point control mechanism for the position of the spot on the information recording surface, and a photo-detection portion for receiving beams reflected by the information recording surface. The structure is divided into a fixed portion including the light source portion and the photo-detection portion and a movable portion including the focusing device (focusing lens) and the focal point control mechanism. At least the movable portion of the separation type optical head is movably accommodated n a frame (sealing case) for the optical head so as to prevent irregular vibrations of the movable portion due to high speed air flows or turbulence. Furthermore, a focal point control mechanism of an air float type may be employed in the movable portion of the separation type optical head so as to actively utilize the high speed air flow generated due to the rotation of the disc medium to perform a rough adjustment of the focal point of the focusing device.

Stack type optical disc apparatus, sealed and separate type optical head

An optical memory device includes a cylindrically-shaped optical information recording medium and at least one optical head disposed around the information recording medium for irradiating the information recording medium with a light spot for recording or reproduction of information. The optical head has light spot moving means incorporated therein for the irradiation position of the light spot. The recording or reproduction of information is achieved by causing the light spot moving means to perform tracking control so that the light spot follows a desired track in an area within a range of movement of the light spot by the light spot moving means (or an infromation recording zone) in a state in which the relative positional relationship between the optical head and the cylindrically-shaped information recording medium in the direction parallel to the direction of the rotation axis of the information recording medium is fixed, with the optical head being not moved. The device can be constructed so that the position of either the optical head or the cylindrically-shaped information recording medium relative to the other in the direction parallel to the direction of the rotation axis of the information recording medium is mechanically moved, thereby making it possible to cahnge the information recording zone in the range of movement of the light spot by the light spot moving means to another information recording zone.

Small-sized optical memory device and information processing apparatus

The present invention relates to a method of recording on a rewritable recording medium using a laser beam capable of producing at least three discreet levels of power. The three levels of power used for writing to the recording medium is greater than the power required for reading. The present method is unique in that the power level of the laser beam is modulated between high, intermediate, and low levels over a time period so that at least three discreet power levels are radiated to the recording medium during recording. The increment of the radiation energy of the upward pulse from the intermediate level toward the high level is within the range of 0.8 to 1.2 times the decrement of the radiation energy of the downward pulse from the intermediate level to the low level. The present invention provides high density recording capability with minimum non-erasure areas even when the recording medium is formed from a high velocity crystallization (high speed erasure).

Information recording method using a modulated recording beam at high,

A method of recording information by changing a recording medium through irradiation with an energy beam such as a light beam, electron beam or the like. A single pulse or a plurality of pulses are employed for forming recorded dots. The pulse has a pulse width shorter than a time required for the center of energy beam spot to move from one to other end of the dot upon recording thereof. By virtue of the possibility of reversible change even in a recording film susceptible to high rate speed of change, the rate of information transfer can be increased. Overwrite recording can also be accomplished with the single laser beam. An increased amount of information can be handled in the recording and reproduction.

An optical information recording carrier which comprises an information recording film susceptible to a change in atomic arrangement upon exposure to a recording beam, a first transparent film for preventing diffusion of heat generated in the recording film upon exposure to the recording beam and provided on each side of the recording film, a second transparent film for diffusing the heat in the in-plane direction of the film and provided on at least one outside thereof, and an organic member further provided on at least one outside thereof, the recording beam being irradiated onto the recording film through the organic member has distinguished characteristics of repeated recordings and erasings.

Optical information phase change recording medium having double

An information recording method and apparatus therefor utilizes an information recording medium having a recording film enabling reversible phase change. The information recording medium is irradiated with an energy beam while relatively moving the information recording medium and the energy beam so as to at least enable recording of information in accordance with phase state changes of the recording film caused by irradiation of the energy beam. The energy beam is modulated so that an intensity of the energy beam obtains a first level having a high power for one portion of coded data information to be recorded, obtains a second level different from the first level for a predetermined time for another portion of the coded data information, and then again obtains the first level to enable recording of the coded data information independently of a previous recording state on the information recording medium.

Information recording medium and apparatus using reversible phase change

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Kokubunji, Japan

Hiroshi Yasuoka