Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Hitachi Global Storage Technologies

Fumio Kugiya

Hisashi Takano

Masaaki Futamoto

Yoshibumi Matsuda

Mikio Suzuki

Kyo Akagi

Yoshinori Miyamura

Takeshi Nakao

Hirotsugu Fukuoka

Takayuki Munemoto

Tokuho Takagaki

Kazuo Shiiki

Toshio Kobayashi

Hideo Tanabe

Naoki Koyama

Masahiro Kitada

Isamu Yuito

Ryoichi Nakatani

Noboru Shimizu

Eijin Moriwaki

Fumiyoshi Kirino

Takeshi Maeda

Hiroyuki Tsuchinaga

Atsushi Saito

Toshimitsu Kaku

Kazuo Shigematsu

Tsuyoshi Toda

Hiroshi Ide

Hisataka Sugiyama

Seiichi Mita

Hajime Aoi

Yasuhide Ouchi

Motoyasu Terao

Akira Arimoto

Norio Ohta

Yoshihiro Shiroishi

Kimio Tatsuno

Hideki Sawaguchi

Nobuyuki Inaba

Kenji Mori

Toshiaki Tsuyoshi

Naoki Kodama

Masahiko Takahashi

Kazuo Sakai

Takuji Ogawa

Kazuo Nakagoshi

Yasuhiro Katoh

Yosuke Seo

Masao Iwakura

Tomio Suzuki

Nobuyuki Okunaga

Takashi Tamura

Makoto Aihara

Tatsuya Ishigaki

Norio Murase

Toshiaki Kojima

Chuma Akira

Tsuyashi Toda

Horishi Ide

Takeshi Nakano

A method of recording data into a recording medium by forming a recording region which is physically different from the nonrecorded portions is disclosed. The optical data recording/reproducing method includes a first trial writing operation in which trial writing data are recorded into the recording medium while changing the recording power conditions, the recorded trial writing data are reproduced, and the reproduced trial writing data are evaluated to set an optimum recording power. The method also includes a second trial writing operation in which trial writing data are recorded into the recording medium while changing the servo conditions, the recorded trial writing data are reproduced, and the reproduced trial writing data are evaluated to set optimum servo conditions.

Magneto-optical data recording/reproducing method

The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.

Method for manufacturing magnetic head device

Magnetic apparatus with perpendicular recording medium and head having multilayered reproducing element using tunneling effect

The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.

Magnetic head with conductors formed on endlayers of a multilayer film having magnetic layer coercive force difference

A magnetic disk drive has a housing for a 3.5 inch form factor and disk media of a diameter for a 2.5 inch form factor. The smaller disk media rotate at a high speed while consuming low electric lower and generating less heat while providing for quick access speeds. Usually, when the magnetic disk media are rotated at a higher speed, the electric power consumption and heat generation are increased because of the load increase. This problem is avoided with the use of cooling fins placed about the periphery of the disk media. Further, the smaller size disk media enable a decrease in torque loss during on-load rotation with the media, and a decrease of electric current to the spindle motor during rotation.

Disc drive having 3.5 inch form factor housing and 2.5 inch form factor disk media

Magnetic disk apparatus including magnetic head having multilayered reproducing element using tunneling effect

The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semicondutor or an antiferromagnetic material against the magnetic layers, and the magneto-resistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-density recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.

Magnetoresistance effect elements and magnetic heads using the tunneling magnetoresistive effect

The magnetoresistance effect element is of a multilayered structure having at least magnetic layers and an intermediate layer of an insulating material, a semiconductor or an antiferromagnetic material against the magnetic layers, and the magnetoresistance effect element has terminals formed at least on the opposite magnetic layers, respectively, so that a current flows in the intermediate layer. The film surfaces of all the magnetic layers constituting the magnetoresistance effect element are opposed substantially at right angles to the recording surface of a magnetic recording medium. Therefore, the area of the magnetic layers facing the recording surface of the magnetic recording medium can be extremely reduced, and thus the magnetic field from a very narrow region of the high-denisity recorded magnetic recording medium can be detected by the current which has a tunneling characteristic and passes through the intermediate layer.

Magnetoresistance effect multilayer film with ferromagnetic film

A super high density optical disk apparatus is obtained by using an exchangeable recording medium having a recording capacity of at least 1.5 Gb/in.sup.2 in an optical recording and reading apparatus for recording or reading at least using a laser beam or by using one of means which can record on a recording medium only once and means which can record at least two times repeatedly as recording means to be used.

Method for recording and reading an optical disk

It is disclosed that a longitudinal magnetic recording medium and apparatus has recording sections having longitudinal magnetic films magnetically isolated in a recording direction. The magnetically isolated recording sections can record a single bit each so that the longitudinal magnetic recording medium can remove the irregular domain boundary of its own caused on boundaries of magnetization reversals in the recording direction. This can improve the signal-to-media noise ratio to a great extent in writing and reading.

Longitudinal magnetic recording medium and apparatus

A magnetic recording medium, its fabrication method, and a magnetic recording apparatus in which both saturation induction and coercive force of a magnetic film is made high as they are near a surface of the recording medium. A high density information recording can be made higher than 50 kFCI in linear recording density even for spacing around 0.2 .mu.m.

Magnetic recording medium having at least two magnetic layers with easy

Multilayer magnetoresistance effect-type magnetic head

A super high density optical disk apparatus is obtained by using an exchangeable recording medium having a recording capacity of at least 1.5 Gb/in.sup.2 in an optical recording and reading apparatus for recording or reading at least using a laser beam or by using one of an element which can record on a recording medium only once and another element which can record at least two times repeatedly as recording elements to be used.

Optical disk apparatus and recording and reading method for an optical

A method and device of head positioning in an information recording/reading device in which a magnetic recording medium with data tracks for recording information thereon is provided and a magnetic head is positioned on the data track to record/read out the information, wherein a data signal is recorded in the data recording layer of said recording medium, a servo signal is recorded in the servo signal recording layer located below said data signal recording layer, said data signal is read out using a data magnetic head whereas said servo signal is read out using a servo magnetic head, and the frequency of said servo signal is within the range of the gap-null frequency of said data magnetic head whereas the frequency of said data signal is within the range of the gap-null frequency of said servo magnetic head, and said magnetic head is positioned on the data track on the basis of said servo signal. A method and device of head positioning in an information recording/reading device in which a magnetic recording medium with data tracks for recording information thereon is provided and a magnetic head is positioned on the data track to record/read out the information, wherein the data tracks are discrete tracks in which adjacent data tracks are separated by a groove located therebetween, a data signal is recorded on the data track of said recording medium, a servo signal is recorded on the servo tracks of grooves between said adjacent data tracks, and said magnetic head is positioned on the data track on the basis of said servo signal.

Method of head positioning and magnetic recording disk drive using the

An optical recording control method determines an optimum recording laser power by effecting a test recording before information to be recorded is recorded on a disk. The recording laser power is formed of a plurality of powers. A relationship among the plurality of laser powers is regulated by power level ratios between respective powers, whereby a power used when a laser light is radiated on the disk can be controlled to be constant independent of an ambient temperature and a structure of a disk. Therefore, accurate recording marks can be formed on the disk.

Method for controlling the farm of a magnetic domain of a

Growing community of inventors

Hachioji, Japan

Fumio Kugiya