Patents by Inventor Takao Koshikawa

Takao Koshikawa 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).

  • Patent number: 7142393
    Abstract: An MR head includes a slider, and a film structure part which is located on an air outflow side of the slider and includes an MR element for reproducing. The film structure part has an end surface located on an identical side as a floating surface of the slider. The end surface of the film structure part and the floating surface of the slider form a step-like recess which has a depth making it possible to prevent a fine projection on a magnetic disk from hitting the end surface of the film structure part.
    Type: Grant
    Filed: July 3, 2001
    Date of Patent: November 28, 2006
    Assignee: Fujitsu Limited
    Inventors: Koki Kanda, Minoru Takahashi, Katsumi Kiuchi, Takao Koshikawa, Katsuhide Sone, Muneo Kamiguchi
  • Patent number: 6594119
    Abstract: A thin film magnetic head has a media opposing surface which is adapted to be opposed to a recording medium, and includes a sacrificial layer, on a substratum that has a surface for forming the media opposing surface having at least one rail. A tracking mechanism or loading/unloading mechanism can be provided on the slider. An electrostatic actuator suitable for driving such a mechanism includes a stationary section having a plurality of teeth parallel to each other, a movable section having a plurality of teeth parallel to the teeth of the stationary section, a support spring for supporting the movable section so that the movable section can be moved with respect to the stationary section in the tooth width direction.
    Type: Grant
    Filed: September 27, 2000
    Date of Patent: July 15, 2003
    Assignee: Fujitsu Limited
    Inventors: Takao Koshikawa, Hiroshi Maeda, Takahiro Imamura
  • Publication number: 20020015265
    Abstract: An MR head includes a slider, and a film structure part which is located on an air outflow side of the slider and includes an MR element for reproducing. The film structure part has an end surface located on an identical side as a floating surface of the slider. The end surface of the film structure part and the floating surface of the slider form a step-like recess which has a depth making it possible to prevent a fine projection on a magnetic disk from hitting the end surface of the film structure part.
    Type: Application
    Filed: July 3, 2001
    Publication date: February 7, 2002
    Applicant: Fujitsu Limited
    Inventors: Koki Kanda, Minoru Takahashi, Katsumi Kiuchi, Takao Koshikawa, Katsuhide Sone, Muneo Kamiguchi
  • Patent number: 6324032
    Abstract: A magnetic recording medium having magnetic patterns into which servo information are written and a magnetic recording layer into which data are written comprises a nonmagnetic substrate, a magnetic recording layer formed on the substrate, and a hard magnetic layer contacting the magnetic recording layer within servo signal recording regions on the substrate and constituting servo patterns of film thicknesses of which are varied in the track length direction. Thereby, more precise reading of the servo signals by the magnetic head is assured and a surface of the magnetic recording medium can be flattend.
    Type: Grant
    Filed: May 7, 1999
    Date of Patent: November 27, 2001
    Assignee: Fujitsu Limited
    Inventors: Yoshinori Ohtsuka, Yoshifumi Mizoshita, Takao Koshikawa, Hiroshi Maeda
  • Patent number: 6295175
    Abstract: When a pin layer magnetic field offset judgment unit judges that a magnetic field in a pin layer of a spin valve head through which a sense current flows in the interference direction has been deviated from a normal direction, a recovery processing unit allows a recovery from the abnormality arising from the magnetic field offset. For example, the direction of the sense current is switched from the interference direction to the assist direction, and the sense current larger than that upon the ordinary reading action is allowed to flow so that the temperature of an antiferromagnetic layer exceeds the blocking temperature, whereby the direction of the magnetic field in the pin layer is modified to the normal direction by the action of a magnetic field generated from the sense current. After the modification, the sense current is returned to have its ordinary value in the interference direction.
    Type: Grant
    Filed: December 22, 1998
    Date of Patent: September 25, 2001
    Assignee: Fujitsu Limited
    Inventors: Isamu Tomita, Takao Koshikawa, Toshinori Hoshino, Tadashi Nakamura, Hitoshi Kanai, Hiroaki Ueno
  • Patent number: 6282061
    Abstract: An MR head includes a slider, and a film structure part which is located on an air outflow side of the slider and includes an MR element for reproducing. The film structure part has an end surface located on an identical side as a floating surface of the slider. The end surface of the film structure part and the floating surface of the slider form a step-like recess which has a depth making it possible to prevent a fine projection on a magnetic disk from hitting the end surface of the film structure part.
    Type: Grant
    Filed: April 16, 1997
    Date of Patent: August 28, 2001
    Assignee: Fujitsu Limited
    Inventors: Koki Kanda, Minoru Takahashi, Katsumi Kiuchi, Takao Koshikawa, Katsuhide Sone, Muneo Kamiguchi
  • Patent number: 6199267
    Abstract: A method for the production of a magnetic head, where first a lower magnetic pole is formed on a wafer. Next, a nonmagnetic write gap layer is formed on the lower magnetic pole. A coil is then formed to be sandwiched between nonmagnetic insulating layers on the nonmagnetic write gap layer. Finally, an upper magnetic pole, provided with a pole tip, is formed to contact the write gap layer on the nonmagnetic write gap layer. After formation, a focused ion beam is irradiated in the direction from a thickness of the pole tip to the lateral parts of the pole tip, the nonmagnetic write gap layer lying directly thereunder. The lower magnetic pole thereby trims the lateral parts of the pole tip while consequently decreasing the width of the pole tip. At the same time, depressed parts are formed in the lower magnetic pole in the areas extending outward from directly below the lateral parts of the pole tip.
    Type: Grant
    Filed: March 31, 1999
    Date of Patent: March 13, 2001
    Assignee: Fujitsu, Limited
    Inventors: Takao Koshikawa, Atsuhiko Nagai
  • Patent number: 6181531
    Abstract: A thin film magnetic head slider has a media opposing surface which is adapted to be opposed to a recording medium, and includes a sacrificial layer, on a substratum that has a surface for forming the media opposing surface having at least one rail. A tracking mechanism or loading/unloading mechanism can be provided on the slider. An electrostatic actuator suitable for driving such a mechanism includes a stationary section having a plurality of teeth parallel to each other, a movable section having a plurality of teeth parallel to the teeth of the stationary section, a support spring for supporting the movable section so that the movable section can be moved with respect to the stationary section in the tooth width direction.
    Type: Grant
    Filed: November 10, 1998
    Date of Patent: January 30, 2001
    Assignee: Fujitsu Limited
    Inventors: Takao Koshikawa, Hiroshi Maeda, Takahiro Imamura
  • Patent number: 6134079
    Abstract: A magnetic head including a magnetic pole piece for forming a recording gap, and a coil interlinked with the magnetic pole piece. The magnetic pole piece is obtained by first preparing a plating solution containing a first component for precipitating a substantially uniform soft magnetic layer of NiFe, for example, next dispersing a second component for precipitating soft magnetic particles of FeN, for example, in the plating solution, and finally simultaneously precipitating the soft magnetic layer and the soft magnetic particles to obtain the magnetic pole piece. The simultaneous precipitation of the soft magnetic layer and the soft magnetic particles may be effected by a dispersion plating method. According to this method, the soft magnetic particles formed of a material having a greater resistivity or a material having a greater saturation magnetic flux density can be mixed in a base layer (the soft magnetic layer) formed of a soft magnetic material that can be electroplated.
    Type: Grant
    Filed: February 27, 1998
    Date of Patent: October 17, 2000
    Assignee: Fujitsu Limited
    Inventor: Takao Koshikawa
  • Patent number: 6083410
    Abstract: A plan or vertical type thin film magnetic head is produced by a process comprising the steps of: forming a gap separator layer of a non-magnetic material on the surface of a substrate, while the forming process is not limited to plating; forming a mask layer on the gap layer; patterning the mask layer to form a shield; etching the gap layer, while the shield functions as a mask, thereby forming a gap wall having a width narrower than that of the shield independent of the resolution degree of the resist; forming a magnetic pole layer of a soft magnetic material on the surface of the substrate by exposing the resist at a time, thereby the formed magnetic pole layer being separated by the gap wall; and, utilizing the gap wall as a magnetic pole gap of the magnetic pole layer.
    Type: Grant
    Filed: October 17, 1997
    Date of Patent: July 4, 2000
    Assignee: Fujitsu Ltd.
    Inventors: Yukinori Ikegawa, Takao Koshikawa, Yoshinori Ohtsuka
  • Patent number: 6055139
    Abstract: A magnetic recording medium having magnetic patterns into which servo information are written and a magnetic recording layer into which data are written comprises a nonmagnetic substrate, a magnetic recording layer formed on the substrate, and a hard magnetic layer contacted the magnetic recording layer within servo signal recording regions on the substrate and constituting servo patterns of film thicknesses of which are varied in the track length direction. Thereby, more precise reading of the servo signals by the magnetic head is assured and a surface of the magnetic recording medium can be flatted.
    Type: Grant
    Filed: December 9, 1996
    Date of Patent: April 25, 2000
    Assignee: Fujitsu Limited
    Inventors: Yoshinori Ohtsuka, Yoshifumi Mizoshita, Takao Koshikawa, Hiroshi Maeda
  • Patent number: 5995339
    Abstract: A magnetoresistive head includes a magnetoresistive element set back from the front end face of the head confronting a record medium for converting changes in a signal magnetic field leaking out from the record track of the record medium into changes in resistance. The magnetoresistive element is connected to a pair of terminals and a sense region is defined between both the terminals. The magnetoresistive element is magnetically coupled to a front flux guide, one end of which is exposed in the front end face of the head, at the other end of the same. The front flux guide is virtually in the form of a rectangle elongated in the direction of the width of the record track of the record medium so as to exceed the sense region of the magnetoresistive element.
    Type: Grant
    Filed: January 27, 1997
    Date of Patent: November 30, 1999
    Assignee: Fujitsu Limited
    Inventors: Takao Koshikawa, Yoshinori Ohtsuka, Yuji Uehara, Junzo Toda, Yoshifumi Mizoshita
  • Patent number: 5966277
    Abstract: A magnetic head comprising a lower magnetic pole formed on a wafer, a nonmagnetic write gap layer formed on the lower magnetic pole, an upper magnetic pole formed on the nonmagnetic write gap layer and provided with a pole tip possessing a thin leading end, two depressed parts formed in the lateral directions from directly below the lateral sides of the pole tip and opposed to each other across areas equal in width with the pole tip, a protective layer of a nonmagnetic insulating material adapted to fill the depressed parts and, at the same time, cover the upper magnetic pole and the lower magnetic pole, and a coil nipped between the opposed parts of a nonmagnetic insulating layer interposed between the upper magnetic pole and the lower magnetic pole.
    Type: Grant
    Filed: December 29, 1997
    Date of Patent: October 12, 1999
    Assignee: Fujitsu Limited
    Inventors: Takao Koshikawa, Atsuhiko Nagai
  • Patent number: 5920978
    Abstract: A method for manufacturing a thin film magnetic head slider having a media opposing surface which is adapted to be opposed to a recording medium, includes the steps of forming on a sacrificial layer, on a substrate, in such a manner that the sacrificial layer has a surface including steps for forming the media opposing surface having at least one rail, providing a slider material on the surface of the sacrificial layer, and removing the sacrificial layer and the substrate from the slider. A tracking mechanism or loading/unloading mechanism can be provided on the slider. An electrostatic actuator suitable for driving such a mechanism includes a stationary section having a plurality of teeth parallel to each other, a movable section having a plurality of teeth parallel to the teeth of the stationary section, a support spring for supporting the movable section so that the movable section can be moved with respect to the stationary section in the tooth width direction.
    Type: Grant
    Filed: February 20, 1996
    Date of Patent: July 13, 1999
    Assignee: Fujitsu Limited
    Inventors: Takao Koshikawa, Hiroshi Maeda, Takahiro Imamura
  • Patent number: 5898542
    Abstract: A magneto-resistive effect type head is provided to suppress the thermal asperity caused by projections or foreign matter found on the recording medium. A step or a protrusion which is closer to the recording medium than the element is provided on the air bearing surface of the head in an area on the leading side of the element with respect to the moving direction of the head.
    Type: Grant
    Filed: September 11, 1998
    Date of Patent: April 27, 1999
    Assignee: Fujitsu Limited
    Inventors: Takao Koshikawa, Yoshifumi Mizoshita
  • Patent number: 5896243
    Abstract: To suppress the thermal asperity in the magneto-resistive effect type head for carrying out the reproduction of signals from the recording medium by the element 2 while moving, in a flying or contact state with the recording medium, in a predetermined direction relative to the recording medium. A step 20 or a protrusion 21 which is closer to the recording medium than the element is provided on the air bearing surface of the head in an area on the leading side of the element with respect to the moving direction of the head.
    Type: Grant
    Filed: November 14, 1996
    Date of Patent: April 20, 1999
    Assignee: Fujitsu Limited
    Inventors: Takao Koshikawa, Yoshifumi Mizoshita
  • Patent number: 5859753
    Abstract: A spin valve magnetoresistive head comprises a first spin valve device having a first magnetization free layer and a first magnetization pinning layer via a first non-magnetic intermediate layer, a second spin valve device having a second magnetization free layer and a second magnetization pinning layer via a second non-magnetic intermediate layer, whereby the first and second magnetization pinning layers are magnetized in anti-parallel to each other and the first and second magnetization free layers are magnetized rotatably based on an external magnetic field.
    Type: Grant
    Filed: December 16, 1996
    Date of Patent: January 12, 1999
    Assignee: Fujitsu Limited
    Inventors: Yoshinori Ohtsuka, Yoshifumi Mizoshita, Takao Koshikawa
  • Patent number: 5793560
    Abstract: A storage device includes a substrate, a magnetic storage medium provided on the substrate, information being magnetically stored in the magnetic storage medium, a head unit, and a reciprocating mechanism provided on the substrate, the reciprocating mechanism causing the head unit to reciprocate in a plane parallel to a surface of the magnetic storage medium, wherein, while the head unit is being moved by the reciprocating mechanism, information is recorded in or reproduced from the magnetic storage medium via the head unit.
    Type: Grant
    Filed: December 19, 1994
    Date of Patent: August 11, 1998
    Assignee: Fujitsu Limited
    Inventors: Yoshifumi Mizoshita, Hiroshi Maeda, Takao Koshikawa, Takayuki Yamamoto
  • Patent number: 5777827
    Abstract: A magneto-resistive (MR) head has an MR layer in a space formed by shield layers by providing a distance enough to protect magnetic flux, flowing through the MR layer from a recording medium through a gap formed by the shield layers, from leaking out to the shield layers. A flux guide is provided between the MR layer and the gap, and has an end magnetically connected to the MR, extending over an effective area of the MR head, and another end having a width a little narrower than a width of track of the recording medium. A side of the MR layer, opposite to the side connected with the flux guide layer is placed in a narrow space formed at a corner of the space. Magnetic flux leaked from the gap due to a sense current flowing through the MR layer is eliminated by making a current flow through a recording coil layer or through an electrically conductive layer placed in the space.
    Type: Grant
    Filed: September 6, 1996
    Date of Patent: July 7, 1998
    Assignee: Fujitsu Limited
    Inventors: Yoshifumi Mizoshita, Takao Koshikawa, Hitoshi Kanai, Junichi Kane, Yoshinori Otsuka, Yukinori Ikegawa
  • Patent number: 5771141
    Abstract: A magnetoresistive head comprises a magnetoresistive layer having an axis of easy magnetization in the direction parallel to an air bearing surface, a first electrode formed on the magnetoresistive layer on the air bearing surface side and an oblique side portion with respect to the air bearing surface, and a second electrode formed to be separated at a distance from the first electrode and having a side portion substantially parallel to the oblique side portion of the first electrode on the magnetoresistive layer.
    Type: Grant
    Filed: December 13, 1996
    Date of Patent: June 23, 1998
    Assignee: Fujitsu Limited
    Inventors: Yoshinori Ohtsuka, Takao Koshikawa, Yoshifumi Mizoshita, Yuji Uehara, Eiichi Kanda, Ken-ichi Aoshima, Hitoshi Kanai, Junichi Kane