Patents by Inventor Tetsuya Okai

Tetsuya Okai has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20020060880
    Abstract: A thin film magnetic head has a magnetic gap and two magnetic films that hold the magnetic gap therebetween to form a magnetic circuit. At least one of the two magnetic films has a first portion the surface of which is located remote from a throat height=0 point, and exposed to a recording medium and which determines a recording track width, and a second portion not exposed to the recording medium. The cross-sectional area of magnetic path in the second portion is larger than that in the first portion.
    Type: Application
    Filed: January 22, 2002
    Publication date: May 23, 2002
    Applicant: Hitachi, Ltd.
    Inventors: Takashi Kawabe, Shinji Narishige, Tadayuki Iwakura, Naoki Koyama, Tetsuya Okai
  • Publication number: 20020041463
    Abstract: Disclosed is a magnetic disk apparatus including a magnetic reproducing head portion, and a magnetic recording head including an upper magnetic core having a end portion and a rear portion. As a resist for a frame which is used for forming the rear portion, a negative resist or an electron beam resist is used, whereby the frame is formed without any adverse effect of halation from a coil insulating film. That is, it is possible to manufacture a magnetic recording head in which the rear portion of an upper magnetic core is not emerged at the face opposed to a medium, and hence to obtain a magnetic disk apparatus exhibiting an areal recording density of 5 Gbit/in2 or more by mounting a magnetic recording/reproducing head including such a magnetic recording head.
    Type: Application
    Filed: July 15, 1999
    Publication date: April 11, 2002
    Inventors: TOMOHIRO OKADA, TETSUYA OKAI, SHINOBU SASAKI, TADAYUKI IWAKURA, NAOKI KOYAMA, TAKASHI KAWABE, HARUNOBU SAITO
  • Publication number: 20020013996
    Abstract: Disclosed is a magnetic disk apparatus including a magnetic reproducing head portion, and a magnetic recording head including an upper magnetic core having a end portion and a rear portion. As a resist for a frame which is used for forming the rear portion, a negative resist or an electron beam resist is used, whereby the frame is formed without any adverse effect of halation from a coil insulating film. That is, it is possible to manufacture a magnetic recording head in which the rear portion of an upper magnetic core is not emerged at the face opposed to a medium, and hence to obtain a magnetic disk apparatus exhibiting an areal recording density of 5 Gbit/in2 or more by mounting a magnetic recording/reproducing head including such a magnetic recording head.
    Type: Application
    Filed: September 28, 2001
    Publication date: February 7, 2002
    Applicant: Hitachi, Ltd.
    Inventors: Tomohiro Okada, Tetsuya Okai, Shinobu Sasaki, Tadayuki Iwakura, Naoki Koyama, Harunobu Saito, Makoto Morijiri
  • Patent number: 5687045
    Abstract: A thin film magnetic head comprising a sintered ceramic substrate, an underlayer, a bottom magnetic core film, a magnetic gap film, an insulating film containing coil windings, a top magnetic core film, and a protective layer. The substrate and other films and layers form an air bearing surface. The under layer, the magnetic gap film and the protective layer comprise Al.sub.2 O.sub.3, and the bottom and the top magnetic core films comprise Ni--Fe alloy. This structure gives substantially the same etching rate, when the air bearing surface is polished using a working fluid of pH 6-8, for any of the substrate, the films comprising Al.sub.2 O.sub.3 and metal oxide described above, and the films of Ni--Fe alloy. Thus, steps (pole top recessions) on the air bearing surface can be made as small as 0.015 .mu.m or less. Accordingly, the magnetic head can be held in a stable attitude, thus obtaining good recording characteristics.
    Type: Grant
    Filed: November 6, 1995
    Date of Patent: November 11, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Tetsuya Okai, Moriaki Fuyama, Akira Onuma, Eiji Ashida, Hiroshi Ikeda, Saburo Suzuki, Yasuo Wakaki, Yoshiki Hagiwara, Eimi Ando
  • Patent number: 5316617
    Abstract: A thin film magnetic head comprising a substrate on which are successively formed a base layer, a lower magnetic film, a gap layer, an insulator layer, a conductor coil, an upper magnetic film, and a first mask, is manufactured by a method in which one or more of a gas which can be expressed by the general formula of CnHxFy (where n.gtoreq.1, x+y=2n+2, x>0, y>0, and x.gtoreq.y); and a gas which can be expressed by the general formula of CnHxFy (where n.gtoreq.1, x+y=2n+2, x.gtoreq.0, y.gtoreq.0, and x<y) is used. The structure of the magnetic head thus obtained is such that, at a height near the interface between the mask and the upper magnetic film provided therebelow, the angle defined by the side edge surfaces of the mask and the above-mentioned interface ranges from 75.degree. to 90.degree..
    Type: Grant
    Filed: May 5, 1993
    Date of Patent: May 31, 1994
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Kawabe, Moriaki Fuyama, Shinji Narishige, Akira Onuma, Tetsuya Okai, Yutaka Sugita, Shin-ichi Hara
  • Patent number: 4971896
    Abstract: A method of forming a thin film pattern on a base having a step portion. This method comprises a first step of forming a thin film of given material on the base, a second step of forming a predetermined pattern of a first photoresist film on said thin film at one of a first portion including a lower part of the step portion and a second portion including an upper part of the step portion, a third step of forming a predetermined pattern of a second photoresist film on said thin film at the other of the first and second portions and a fourth step of applying ion-milling to said thin film of given material using masks said first and second photoresist film patterns formed on said thin film at the first and second portions.
    Type: Grant
    Filed: December 7, 1988
    Date of Patent: November 20, 1990
    Assignee: Hitachi, Ltd.
    Inventors: Takashi Kawabe, Ataru Kobayashi, Moriaki Fuyama, Makoto Morijiri, Eiji Ashida, Masatoshi Tsuchiya, Tetsuya Okai, Masanobu Hanazono, Shinichi Hara, Shinji Narishige, Hiroshi Ikeda