Hitachi, Ltd.

Hitachi Maxell, Limited

Hitachi Global Storage Technologies Japan, Ltd.

Kazuetsu Yoshida

Masaaki Futamoto

Yukio Honda

Yoshiyuki Hirayama

Nobuyuki Inaba

Yohji Maruyama

Masukazu Igarashi

Kenya Ito

Ikuo Saitoh

Hiroyuki Suzuki

Yoshihiro Shiroishi

Akira Ishikawa

Atsushi Kikugawa

Kiwamu Tanahashi

Takanobu Takayama

Yuzuru Hosoe

Hideki Saga

Mikio Suzuki

Tomoo Yamamoto

Hiroaki Nemoto

Sadao Hishiyama

Norikazu Tsumita

Tomoyuki Ohno

Yasutaro Uesaka

Fumiko Akagi

Takashi Nishimura

Osamu Kitakami

Yasushi Kitazaki

Makoto Saito

Shinichiro Saito

Hideo Fujiwara

Yoshibumi Matsuda

Katsuhiro Kuroda

Fumiyoshi Kirino

Kazuo Shiiki

Yotsuo Yahisa

Kazumasa Takagi

Shinji Narishige

Masaki Ohura

Hajime Aoi

Naoki Kodama

Takeo Yamashita

Toshio Niihara

Futoshi Tomiyama

Heigo Ishihara

Hideo Daimon

Katsuo Abe

Kunio Wakai

Sadanori Nagaike

Hiroyuki Kataoka

Kazusuke Yamanaka

Keiichi Kanehori

Akira Osaki

Seiichi Asada

Toyoji Okuwaki

Katsuhiro Kaneko

Susumu Funamoto

Emi Mangyo

Hitoshi Iwata

Michiharu Seki

Sakae Ohta

Shyuichi Kojima

Kazushige Imagawa

Yo Sakurai

Selichi Asada

A perpendicular magnetic recording medium which has been improved to be suitable for high-density magnetic recording and a magnetic recording apparatus using the medium are provided. The magnetic back film of a dual-layer perpendicular recording medium is caused to be constituted by a plurality of layers, and a keeper layerfor keeping perpendicular magnetization and layersandfor improving the recording efficiency of a recording head are functionally separated from one another. Further, the magnetization orientations of the soft magnetic films excluding the keeper layer are defined to be in the circumferential direction of the disk, whereby the frequency of occurrence of noise is decreased.

Perpendicular magnetic recording media, magnetic recording apparatus

The present invention relates to perpendicular magnetic recording media using a ferromagnetic film provided with perpendicular magnetic anisotropy for a recording layer and a magnetic recording apparatus using the media, and the object is to provide the perpendicular magnetic recording media which are excellent in signal to noise ratio (S/N) in a large recording density region, which are stable against thermal fluctuation and which can be easily manufactured, and the magnetic recording apparatus using the media. The representative perpendicular magnetic recording media according to the invention include a glass substrate, a first recording layer which is provided on the substrate via an underlayer, which has perpendicular magnetic anisotropy and the magnitude of magnetic exchange interaction between grains of which is substantially zero and a second recording layer which is laminated on the first recording layer, which is provided with perpendicular magnetic anisotropy and the magnetic exchange interaction between grains of which is larger than that of the first recording layer.

Perpendicular-magnetic recording media and magnetic recording apparatus

In an optical recording and magnetic-head reproducing system, the reproduced output is prevented from starting to decrease, upon the length of record bits getting shorter, in the range of the bit length larger than reproducing resolution of a magnetic reproducing head. When data are recorded magneto-optically on a magnetic recording medium, the radius of curvature of arcs constituting the boundary of recorded magnetic domains is made as large as possible so that the shape of the recorded spot may be substantially rectangular. As a result, it becomes possible to improve the efficiency of magnetic reproduction, and high-output as well as high-SN-ratio reproduction at high linear recording density can be achieved.

Magnetic recording device

A recording equalizer for correcting a write timing of magnetic information when the magnetic information is recorded with a magnetic recording head on a magnetic recording medium, includes a buffer for storing a recording object bit and bits before and after the recording object bit and a calculator for calculating a precompensation parameter using the bits stored in the buffer. The calculator calculates the preconpensation parameter of the recording object bit by linearly adding influence of a transition existing at a two-previous bit of the recording object bit, influences of a transition at a one-previous bit of the recording object bit and influences of a transition existing at one-following bit of the recording object bit and further adding an offset. The offset is determined to a value such that a write timing of the magnetic information is corrected always in a delaying direction.

Recording equalizer and magnetic recording/reproducing apparatus using the equalizer

Magnetic recording medium includes at least two layers having different magnetic anisotropy constants formed on a substrate and the perpendicular magnetic anisotropy of the second magnetic film of those magnetic films, far from the substrate surface, made equal to or larger than that of the first magnetic film near to the substrate surface, thus improving the magnetic isolation.

Magnetic recording medium and magnetic recording apparatus using the same

A perpendicular magnetic recording medium which has been improved to be suitable for high-density magnetic recording and a magnetic recording apparatus using the medium are provided. The magnetic back film of a dual-layer perpendicular recording medium is caused to be constituted by a plurality of layers, and a keeper layer for keeping perpendicular magnetization and layers and for improving the recording efficiency of a recording head are functionally separated from one another. Further, the magnetization orientations of the soft magnetic films excluding the keeper layer are defined to be in the circumferential direction of the disk, whereby the frequency of occurrence of noise is decreased.

A magnetic recording system includes a magnetic recording medium including a magnetic layer, the magnetic layer being composed of magnetic grains, and a magnetic head including a recording unit and a reproducing unit. An orientation of an axis of easy magnetization of the magnetic grains is three-dimensionally distributed. An average angle between a direction of an axis of easy magnetization of each of the magnetic grains and a surface of the magnetic recording medium is within a range of 20&deg; to 30&deg;. A squareness ratio Mr/Ms of a remanent magnetization Mr of the magnetic recording medium to a saturation magnetization Ms of the magnetic recording medium is equal to 0.5 or more and is equal to 0.6 or less. A recording density of information which is recorded onto the magnetic recording medium is equal to 360 kfci or more.

Magnetic recording system including magnetic recording medium having three-dimensional random orientation of axis of easy magnetization

A magnetic recording medium has a magnetic recording film in which the magnitude of saturation magnetization Ms(T&equals;5&deg; K) at 5&deg; K and magnitude of saturation magnetization Ms(T&equals;300&deg; K) at 300&deg; K satisfy: Ms(T&equals;300&deg; K)/Ms(T&equals;5&deg; K)&gE;0.75. The recording medium enables the high-density recording, and a magnetic recording apparatus using this recording medium can yield a sufficiently high reproduction signal level within the operating temperature range of the apparatus.

Magnetic recording medium and magnetic recording apparatus

A recording equalizer for correcting a write timing of magnetic information when the magnetic information is recorded with a magnetic recording head on a magnetic recording medium, includes a buffer for storing a recording object bit and bits before and after the recording object bit and a calculator for calculating a precompensation parameter using the bits stored in the buffer. The calculator calculates the precompensation parameter of the recording object bit by linearly adding influence of a transition existing at a two-previous bit of the recording object bit, influences of a transition at a one-previous bit of the recording object bit and influences of a transition existing at one-following bit of the recording object bit and further adding an offset. The offset is determined to a value such that a write timing of the magnetic information is corrected always in a delaying direction.

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Hidaka, Japan

Kazuetsu Yoshida