Hitachi Maxell, Limited

Hitachi Maxwell, Ltd.

Makoto Iimura

Makoto Miyamoto

Naoki Kitagaki

Yoshihiro Ikari

Akira Kashiwakura

Reiji Tamura

Hiroshi Shirai

Kazuyoshi Adachi

Tamotsu Fuchioka

Yutaka Watanabe

Satoshi Sukada

Mayumi Kurokawa

Sonoko Onodera

Kazuyo Umezawa

The reproduction durability of an optical recording medium is evaluated highly accurately in a short period of time by providing a method for evaluating the optical recording medium, the method including determining an operating laser power for heating a recording layer to a recording operating temperature; determining a temperature of the recording layer when a laser beam having a predetermined reproducing laser power is radiated during a data reproduction; determining a relationship between the reproducing laser power during the data reproduction and a reproduction durability times at the reproducing laser power; and determining a relationship between the temperature of the recording layer during the data reproduction and the reproduction durability times from the relationship between the reproducing laser power during the data reproduction and the reproduction durability times.

Method for evaluating optical recording medium, optical recording medium, and information-recording/reproducing apparatus

In an information recording medium, a Bi&#x2014;Ge&#x2014;Te material is adopted as a phase-change recording layer material. A C&#x2014;Ta&#x2014;O material is used for at least any one of first and second boundary layers which are in contact with a recording layer.

Information recording medium

A phase-change optical recording medium capable of performing recording and reproduction at a high speed is provided, in which a reproduced signal output is not only sufficiently large but the phase-change optical recording medium also has excellent repeated rewriting performance. An interface layer, which is composed of a Ge&#x2014;Si&#x2014;N-based material, is formed on at least a surface of one side of a recording layerof the phase-change optical recording medium. Accordingly, even when a phase-change material having a high melting point, for example, a Bi&#x2014;Ge&#x2014;Te-based phase-change material is used for the recording layer, it is possible to provide the phase-change optical recording medium in which the reproduced signal output is sufficiently large and the repeated rewriting performance is excellent.

Phase-change optical recording medium

A write-once optical information recording medium is provided that is capable of realizing a high transfer rate and a method of recording and reproducing information on and from the optical information recording medium. The optical information recording medium is constructed by stacking a reflective layer, a first dielectric layer, a recording layer, a write-protect layer, a second dielectric layerand a transparent cover layeron a polycarbonate substrate. The recording layeris made of a phase-change material, and the cover layeris made of UV curing resin. The recording layeris irradiated with a laser beam with a wavelength of 500 nm or less to change from a crystalline phase to an amorphous phase. The write-protect layerprevents the recording layerfrom changing back to the crystalline phase from the amorphous phase, formed by the phase change.

Optical information recording medium and method of recording and reproducing information on and from optical information recording medium

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Ibaraki, Japan

Makoto Iimura