Hitachi Maxell, Limited

Yuji Yamazaki

Hiroyuki Awano

Makoto Miyamoto

Katsusuke Shimazaki

Hiroki Takao

Naoki Kitagaki

Susumu Imai

Toshinori Sugiyama

Reiji Tamura

Tamotsu Iida

Masaki Sekine

Toshiaki Taii

Hideki Nagano

An optical disk includes a recording region formed on a substrate for recording user data, and a management region formed on the substrate which includes an identification information region for recording disk-specific identification information such as address information (ID), a SYNC code, or an error detection code (EDC). The identification information region in this optical disk has a flat portion (a mirror region) formed by means of sectioning part of a groove or a land in a given step. The disk-specific identification information is recorded on the identification information region inclusive of this mirror region as irreversible record marks. Moreover, a signal of the disk-specific identification information is detected by a laser beam which is servoed on the recording track of this optical disk. Then, a change in the detected signal level of the disk-specific identification information is detected based on a predetermined threshold level.

Optical disk, method of playing optical disk, and optical disk drive

An information-recording method and an information-recording medium which make it possible to improve overwrite characteristics in the high speed recording, especially archival overwrite characteristics for overwriting information after retaining the medium in a high temperature environment for a certain period of time, and an information-recording apparatus based on the use of the same are provided. The information-recording method comprises overwriting a random pattern with light beams having a predetermined recording power and a variety of erasing powers; reproducing the random pattern to determine a minimum value Pband a maximum value Pbof the erasing power obtained when the pattern, in which a reproduction jitter exceeds a predetermined threshold value, is erased; determining an optimum erasing power Pb from the minimum value Pb, the maximum value Pb, and a relational expression represented by Pb=&#x3b1;&#xd7;Pb+(1&#x2212;&#x3b1;)&#xd7;Pb; and recording the information with the determined optimum erasing power Pb. The value of &#x3b1; is previously recorded on the information-recording medium. The information-recording apparatus has a Pb-calculating control unit which reads the value of &#x3b1; when the optimum erasing power Pb is determined.

Information recording method and medium having optimum erasing power

An information-recording method and an information-recording medium which make it possible to improve overwrite characteristics in the high speed recording, especially archival overwrite characteristics for overwriting information after retaining the medium in a high temperature environment for a certain period of time, and an information-recording apparatus based on the use of the same are provided. The information-recording method comprises overwriting a random pattern with light-beams having a predetermined recording power and a variety of erasing powers; reproducing the random pattern to determine a minimum value Pband a maximum value Pbof the erasing power obtained when the pattern, in which a reproduction jitter exceeds a predetermined threshold value, is erased; determining an optimum erasing power Pb from the minimum value Pb, the maximum value Pb, and a relational expression represented by Pb=&#x3b1;&#xd7;Pb+(1&#x2212;&#x3b1;)&#xd7;Pb; and recording the information with the determined optimum erasing power Pb. The value of &#x3b1; is previously recorded on the information-recording medium. The information-recording apparatus has a Pb-calculating control unit which reads the value of &#x3b1; when the optimum erasing power Pb is determined.

Information recording method, information recording medium and information recording apparatus

A magnetic recording medium comprises, on a substrate, a recording auxiliary layer, a recording holding layer, recording control layer, and a recording layer. The recording layer is constructed by using a ferri-magnetic material having perpendicular magnetization. The data can be recorded at a super high density by using the recording and reproducing head of the present invention, because the recording layer has the perpendicular magnetization. The disappearance of data, which would be otherwise caused by the thermomagnetic relaxation phenomenon, is suppressed after recording the data, because the recording layer has large coercive force at the room temperature. The data, which is recorded at the super high density on the magnetic recording medium, can be reproduced by using a magnetic resistance element carried on the recording and reproducing head.

Magneto-optical recording and reproducing method, using reproducing layer with high saturation magnetization

While a magneto-optical recording medium is irradiated with a laser beam, the medium is rotated relative to the beam at a controlled speed in such a manner that a high temperature region of a heat spot produced on the basis of the light intensity distribution of the beam is formed outside the associated light spot. A magnetic field source includes a magnetic field generator which is narrow in the direction along the track of the medium. The field source is positioned with the field generator at the heat center outside the light spot to apply a narrow recording magnetic field to the high temperature region. This forms a recording magnetic domain in the high temperature region. The magnetic domain is rectangular and narrow in the direction along the track. Rectangular recording magnetic domains adjoining in the direction along the track hardly interfere with each other even if they are closely spaced. This results in high density recording.

Recording method, reproducing method and recording and reproducing apparatus for magneto-optical recording medium

Magnetic recording medium, recording and reproducing head, and magnetic recording and reproducing method

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Toride, Japan

Yuji Yamazaki