Mitsubishi Kagaku Media Co., Ltd.

Mitsubishi Chemical Corporation

Hitachi Maxell, Limited

Hideyuki Kubo

Michikazu Horie

Masae Kubo

Takashi Ohno

Hironobu Mizuno

Masaaki Mizuno

Hideharu Takeshima

Haruo Kunitomo

Ken-Ichi Takada

Yutaka Kurose

Kenjirou Kiyono

Hironori Ota

Yoshihiro Noda

Takeshi Kuriwada

Hideki Nagano

Joji Kondo

In an optical recording medium having a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, an optimum recording power to each of the recording layers can be determined. The optical recording medium has a plurality of recording layers on which information can be recorded by irradiating a laser beam from one side thereof, and each of the recording layers has a power calibration area (PCA) for optimizing the intensity of the laser beam.

Optical recording medium with power calibration areas and a recording method therefor with optimum power control

In an optical recording medium of a single-sided incident type having a plurality of recording layers, recording/reading conditions (for example, tracking polarity, recording pulse strategy, recording recommended power, etc.) can be instantaneously switched according to each of the recording layer, and recording or reading of information can be accurately and surely performed under recording/reading conditions adapted to each recording layer. A control unit reads out layer information from one recording layer of the optical recording medium in which the layer information is recorded in each of the plural layers, on which recording or reading of information can be performed by irradiating a laser beam from one side thereof (layer information reading step), and controls so that recording or reading is performed under recording/reading conditions adapted to a recording layer specified on the basis of the layer information (recording controlling step).

Recording/reading method for an optical recording medium using an irradiating a laser beam

By use of a substrate which can be stably formed and has a relatively small groove depth, a very high density optical recording medium having good recording/reading characteristics is provided. In an optical recording medium of a surface incidence type, in which a reflective layer, a recording layer containing a dye as a main component and a cover layer are sequentially formed on a substrate having guide grooves formed therein, a guide groove part on a far side from a plane of incidence of a recording/reading light beam on the cover layer is set as a recording groove part, and reflected light intensity in a recorded pit portion formed in the recording groove part is increased by a phase shift and is set higher than reflected light intensity in unrecorded.

Optical recording medium and optical recording method of the same

An information recording method allows optical information having a recording mark length smaller than a spot diameter of laser light to be recorded on an optical recording medium having a recording layer, at high density by laser light pulse application. The information recording method has: a power calibration step of determining a recording power for recording a signal having a predetermined signal length in the recording layer using the laser light; and a complementing step of complementing, based on the recording power determined in the power calibration step, a recording power for recording a signal having a signal length equal to or less than &#xbd; of the spot diameter of the laser light in the recording layer using the laser light. In the information recording method, for example, an extremely small mark, such as a 2T signal, can be precisely formed.

Information recording method and information recording medium

Optical recording method and medium on which recording and/or reading are performed from one side

To provide a rewritable compact disk having a rewritable area interchangeable with a CD-RW, that is, a RAM area ( ), and an area available only for retrieving, that is, a ROM area ( ), on the same disk surface, a phase-change recording layer is formed in each of the RAM area and the ROM area, with a wobble groove being made in the RAM area, irradiation is carried out with recording light so that an amorphous mark is formed to record information and information is recorded in the form of a pre-pit string ( ) in the ROM area, and further when measured using a wavelength of 770 to 790 nm and an optical pickup whose objective lens numerical aperture is 0.49 to 0.51, a ratio &verbar;I &minus;I &verbar;/&verbar;I &minus;I &verbar; of values of push pull signals before and after recording in the RAM area is set to be in a range from 1.05 to 2.0, or a ratio &verbar;I &minus;I &verbar; /&verbar;I &minus;I &verbar; of a value of a push pull signal after recording in the RAM area to a value of a push pull signal in the ROM area is set to be in a range from 0.78 to 1.3.

Rewritable compact disk and manufacturing method thereof

An optical phase-change disc comprises a substrate having thereon a spiral groove or concentric grooves for guiding a focused light beam, and a layer structure including a recording layer and protective layers sandwiching therebetween the recording layer. The groove has wobble for recording ATIP (absolute time information) or ADIP (address information). The following relationship between the groove width GW, beam diameter R.sub.0 and wobble amplitude a.sub.w :

Optical phase-change disc

Optical phase-change disc having a grooved substrate, with the groove

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Tokyo, Japan

Hideyuki Kubo