Hitachi Maxell, Limited

Hitachi Maxwell, Ltd.

Naoki Kitagaki

Makoto Miyamoto

Yuji Yamazaki

Makoto Iimura

Osamu Ishizaki

Tsuyoshi Maro

Hideo Daimon

Yoshihiro Ikari

Akira Kashiwakura

Kazuyoshi Adachi

Satoshi Sukada

Yutaka Watanabe

Mayumi Kurokawa

Sonoko Onodera

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

An information-recording method includes the steps of moving a light beam at a selected linear velocity relative to the information-recording medium; controlling the light beam to generate a multi-pulse having at least three power levels of a first power level Ph, a second power level Pwhich is lower than the first power level, and a third power level Pm which is intermediate therebetween, the multi-pulse being repeatedly modulated between the first power level Ph and the third power level Pm; adjusting the third power level Pm in response to the selected linear velocity; and recording the information by irradiating the information-recording medium with the controlled light beam. Recording compatibility can be secured for information-recording apparatuses different in recording linear velocity and laser source characteristic.

Information-recording method and information-recording medium

An information-recording method includes the steps of moving a light beam at a selected linear velocity relative to the information-recording medium; controlling the light beam to generate a multi-pulse having at least three power levels of a first power level Ph, a second power level Pl which is lower than the first power level, and a third power level Pm which is intermediate therebetween, the multi-pulse being repeatedly modulated between the first power level Ph and the third power level Pm; adjusting the third power level Pm in response to the selected linear velocity; and recording the information by irradiating the information-recording medium with the controlled light beam. Recording compatibility can be secured for information-recording apparatuses different in recording linear velocity and laser source characteristic.

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 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

The present invention provides a magnetic recording medium with distinguished SNR and mechanical characteristics, which comprises an underlayer, a ferromagnetic thin film metallic layer and a protective film layer successively and continuously laminated on a non-magnetic resin substrate, where (A) at least one layer selected from the group consisting of an Si layer, an Si.sub.w N.sub.x C.sub.y O.sub.z layer and an Al.sub.w N.sub.x C.sub.y O.sub.z layer and (B) at least one layer selected from the group consisting of silicides, nitrides, oxides or their mixtures of Ti, Ta, Mo, V, Zr and their alloys are laminated on the non-magnetic resin substrate in the order of (A) and (B) or (i) a layer composed of at least one material selected from the group consisting of Ti, Ta, Mo, V, Zr, Nb and their alloys, (ii) at least one layer selected from the group consisting of an Si layer, an Si.sub.w N.sub.x C.sub.y O.sub.z layer and an Al.sub.w N.sub.x C.sub.y O.sub.z layer (where w+x+y+z=100 at. %, w.gtoreq.30 at. %, 0 .ltoreq.z.ltoreq.50 at. % and x+y.gtoreq.20 at. %), and (iii) a layer composed of at least one material selected from the group consisting of Ti, Ta, Mo, V, Zr and their alloys are laminated on the non-magnetic resin substrate in the order of (i), (ii) and (iii), between the non-magnetic resin substrate and the underlayer.

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Moriya, Japan

Naoki Kitagaki