Sony Corporation

Du Pont-mitsui Polychemicals Co., Ltd.

Hiroshi Uchiyama

Yusuke Suzuki

Takao Kudo

Hisayuki Yamatsu

Norihiro Tanabe

Kazuya Hayashibe

Yoshihito Fukushima

Takanori Sato

Tomio Kobayashi

Shigeki Takagawa

Noriyuki Saito

Yo Ota

Tomoki Kanesaka

Kaoru Suzuki

Naoki Honda

Nobuhiro Nagano

Susumu Haga

Katsumi Miura

Norihiko Sato

There is provided an optical recording medium including a substrate, an information recording layer that is formed on the substrate and has a single film structure formed by an oxide including W and Ru, and a light transmissive layer that is formed on the information recording layer.

Optical recording medium and manufacturing method of optical recording medium

An optical disc manufacturing method includes: an injection step of injecting a liquid material into a circular plate-shaped injection space having a center hole portion at a center from an injection hole connected to an inner edge portion in the injection space; a discharge step of discharging air and the liquid material from a discharge hole formed on a straight line passing through the injection hole and a center of the center hole portion in a plane direction of the circular plate and at a position opposite to the injection hole; a curing step of curing the liquid material injected into the injection space; and a takeout step of taking out the cured liquid material from the injection space.

Optical disc manufacturing method

An optical information recording medium includes a recording layer that absorbs recording light in accordance with its wavelength, the recording light being condensed for information recording, and increases the temperature in the vicinity of a focus so as to form a recording mark and that has properties of increasing a light absorption amount with respect to the wavelength of the recording light by heating performed at a temperature of 120&#xb0; C. or more.

Optical information recording medium

An optical information recording medium includes a recording layer that includes a mark layer in which recording marks formed in accordance with condensed recording light are aligned and has a recording light absorption amount of 20.8% or less with respect to an innermost depth as a depth of the mark layer from a side thereof that the recording light enters to a side thereof that is most distant from the side that the recording light enters, and a change amount of a light absorption amount with respect to measurement light having a wavelength 10 nm shorter than that of the recording light at a time a light absorption amount with respect to measurement light having the same wavelength as the recording light is used as a reference, of 8.0% or more per 0.30 mm.

Optical information recording medium capable of changing the light absorption amount

An optical information recording medium, which is made of a resin provided with photoreactivity containing organometal compound, has a recording layer on which, after a photoreaction are brought about when predetermined initialization light is irradiated to the medium and then the resin is hardened, at a time of recording information, a recording mark is formed when predetermined recording light is condensed to the medium, and a temperature of the medium near a focal point of the recording light is increased and the organometal compound is transubstantiated, and at a time of reproducing information, the information is reproduced based on returned light according to predetermined reading light being irradiated.

An optical information recording and reproducing deviceirradiates initialization light Lto an optical information recording mediumhaving a recording layermade of photopolymerization-type photopolymer in advance to bring about the photopolymerization or the photocrosslinking to perform the initialization processing, and condenses a recording light beam Lhaving a comparatively strong light intensity to a target position in the recording layerand increases the temperature thereof to transubstantiate the target position to record a recording mark RM at the time of recording information, and condenses a reading light beam Lhaving a comparatively weak light intensity to the target position and receives a returned light beam Lhaving a sufficient light amount reflected by the recording mark RM at the time of reproducing information, which makes it possible to reliably record the recording mark RM and stably read out the recording mark RM.

Method of recording in an optical information recording medium

A magnetic recording medium having pits corresponding to servo signals and grooves extending along recording tracks, in which a magnetic head undergoes only little variations in its floating amount during recording/reproduction. The ratio Lw/Gw, where Lw is the width of a land 4 as a protuberant portion between neighboring grooves 3 and Gw is the width of the groove 3, is set so as to be not less than 2.0.

Magnetic recording medium, magnetic recording/reproducing apparatus and

A magnetic disk yields an excellent off-track characteristics and a high coercive force if a track density is increased. The magnetic disk includes a non-magnetic plate on which data such as a servo signal is formed by convexo-concave patterns and an metallic magnetic film formed on the non-magnetic plate. The metallic magnetic film has a thickness of 50 nm or lower. Between the non-magnetic plate and the metallic magnetic film is formed a primary coat composed of a first and a second coats. The first coat is made of any one of C, Si and Ge and the second coat is made of Cr as a main component. The first coat has a thickness of 2 to 80 nm. The second coat has a thickness of 5 to 108 nm.

Magnetic disk

Magnetic recording medium

The coefficient k.sub.1 of linear expansion in a temperature range from 50.degree. to 300.degree. C. of a non-magnetic support member of a recording medium, before a Co-Cr alloy film is formed thereon, is less than 0 mm/mm .degree.C., and the coefficient k.sub.2 of linear expansion in a temperature range from 50.degree. to 300.degree. C. of that support member after the Co-Cr alloy film is formed is less than 0.3.times.10.sup.-5 mm/mm .degree.C. The alloy film also includes carbon in the magnetic layer, and a protective film comprised of carbon is further formed on the magnetic layer. The recording medium is particularly adapted for perpendicular magnetic recording.

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Miyagi, Japan

Hiroshi Uchiyama