Patents by Inventor Naoki Ohta

Naoki Ohta 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: 7952839
    Abstract: An MR element includes a first ferromagnetic layer, a second ferromagnetic layer, a spacer layer disposed between the first and second ferromagnetic layers; and an antiferromagnetic layer disposed on a side of the first ferromagnetic layer farther from the spacer layer. The antiferromagnetic layer is disposed away from a detection surface. The first ferromagnetic layer includes: a first portion having an end face located in the detection surface and a rear end opposite to the end face; and a second portion located away from the detection surface and connected to the rear end of the first portion. The first portion has a first surface touching the spacer layer, and a second surface that is opposite to the first surface and that does not touch the antiferromagnetic layer. The second portion has a third surface touching the antiferromagnetic layer, and a fourth surface opposite to the third surface.
    Type: Grant
    Filed: January 28, 2008
    Date of Patent: May 31, 2011
    Assignee: TDK Corporation
    Inventors: Hiroshi Yamazaki, Naoki Ohta
  • Patent number: 7948713
    Abstract: A magnetic head slider includes at least one thin-film magnetic head formed on a trailing surface of the magnetic head slider, and an ABS to be faced a magnetic disk in operation. At least a part of the ABS is made of a giant magnetostrictive material.
    Type: Grant
    Filed: January 12, 2007
    Date of Patent: May 24, 2011
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Kei Hirata
  • Patent number: 7933099
    Abstract: A magnetic head having precisely controlled MR height has a slider substrate and a magnetic head part provided on the slider substrate. The magnetic head part includes, seeing from a medium-opposing surface side, a magnetism detecting element; an upper magnetic shield layer arranged on the magnetism detecting element; an electrode layer separated in a track width direction from the upper magnetic shield layer; and a conductor layer, arranged closer to the slider substrate than are the upper magnetic shield layer and electrode layer, extending in the track width direction so as to be in contact with the upper magnetic shield layer and electrode layer and forming a part of the medium-opposing surface.
    Type: Grant
    Filed: April 11, 2007
    Date of Patent: April 26, 2011
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Tetsuya Kuwashima, Kazuki Sato, Kosuke Tanaka
  • Patent number: 7916432
    Abstract: The thin-film patterning method for a magnetoresistive device comprises forming a functional layer on a substrate; forming a first mask layer above the functional layer; forming a patterned resist on the first mask layer; etching the first mask layer by using the resist; removing the resist; forming a second mask layer by atomic layer deposition, the second mask layer covering a step defined by an edge of the first mask layer; dry-etching the second mask layer in a thickness direction of the substrate so as to leave the second mask layer on a side face of the step; removing the first mask layer so as to expose the functional layer under the first mask; and dry-etching the functional layer by using the second mask layer.
    Type: Grant
    Filed: December 11, 2007
    Date of Patent: March 29, 2011
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Kazuki Sato, Kosuke Tanaka
  • Publication number: 20110068786
    Abstract: A magnetic sensor includes: a first and a second magnetoresistive elements each including: a magnetization free layer; a nonmagnetic spacing layer; a magnetization pinned layer having one or more first layers of a first group of ferromagnetic layers and one or more second layers of a second group of ferromagnetic layers, in which the first layer and the second layer are stacked alternately with a nonmagnetic coupling layer in between, and so antiferromagnetically coupled to each other as to have opposite magnetizations to each other; and an antiferromagnetic layer pinning magnetization orientation in the one or more first and the second layers. The first layers in the first magnetoresistive element are one more in number than that of the one or more second layers. The number of the one or more first layers and that of the one or more second layers in the second magnetoresistive element are equal.
    Type: Application
    Filed: September 13, 2010
    Publication date: March 24, 2011
    Applicant: TDK CORPORATION
    Inventors: Naoki OHTA, Koichi Terunuma, Satoshi Miura, Masanori Sakai, Hiroshi Yamazaki
  • Patent number: 7894166
    Abstract: A magneto-resistive effect device of a CPP structure includes a nonmagnetic intermediate layer, and a first ferromagnetic layer and a second ferromagnetic layer stacked together and formed with the nonmagnetic intermediate layer sandwiched between them. The first ferromagnetic layer and the second ferromagnetic layer are magnetically coupled via the nonmagnetic intermediate layer such that magnetizations of the first ferromagnetic layer and the second ferromagnetic layer are antiparallel with each other. Mutually antiparallel magnetizations of two magnetic layers lie in a medium opposite plane or front to rear direction and in a rear to front direction. The second ferromagnetic layer is divided by a nonmagnetic intervening layer into a front second ferromagnetic layer and a rear second ferromagnetic layer on the way from the front to the rear.
    Type: Grant
    Filed: October 25, 2007
    Date of Patent: February 22, 2011
    Assignee: TDK Corporation
    Inventors: Hiroshi Yamazaki, Naoki Ohta
  • Publication number: 20110025320
    Abstract: A magnetoresistive element includes magnetoresistive films each having an upper surface and a lower surface, and conductors combining the magnetoresistive films in series and including top electrodes and bottom electrodes. Each one of the top electrodes and corresponding one of the bottom electrodes oppose each other to sandwich corresponding one of the magnetoresistive films. Each electrode of the top electrodes and the bottom electrodes includes a stem section and a branch section, the stem section extending in a direction along a series alignment direction of the magnetoresistive films, and the branch section extending along the lamination plane in a direction intersecting a direction in which the stem section extends. The branch section in the top electrode is in contact with an upper surface of the corresponding magnetoresistive film, and the branch section in the bottom electrode is in contact with a lower surface of the corresponding magnetoresistive film.
    Type: Application
    Filed: July 27, 2010
    Publication date: February 3, 2011
    Applicant: TDK CORPORATION
    Inventors: Naoki OHTA, Masanori Sakai, Hiraku Hirabayashi
  • Publication number: 20110025322
    Abstract: A magneto-resistance effect element for a sensor to sense a variation in externally applied magnetism includes a pinned layer having a fixed magnetization direction, a free layer having a magnetization direction which varies in response to an external magnetic field, and an intermediate layer provided between the pinned layer and the free layer. The pinned layer has a planar shape which is long in the fixed magnetization direction and which is short in a direction orthogonal to the fixed magnetization direction. Moreover, the pinned layer preferably has a planar shape in which the pinned layer is divided into a plurality of sections.
    Type: Application
    Filed: July 29, 2010
    Publication date: February 3, 2011
    Applicant: TDK CORPORATION
    Inventors: Hiroshi YAMAZAKI, Hiraku Hirabayashi, Naoki Ohta
  • Publication number: 20110025321
    Abstract: A magnetic sensor includes first to fourth MR elements. The first and second MR elements are connected at respective ends thereof through a first connecting portion in a central region. The third and fourth MR elements are connected at respective ends thereof through a second connecting portion that crosses the first connecting portion with a distance in a thickness direction in the central region. The first and fourth MR elements are connected at respective other ends thereof through a third connecting portion, and the second and third MR elements are connected at respective other ends thereof through a fourth connecting portion. Resistance values of the first and third MR elements change in a same increasing/decreasing direction, whereas resistance values of the second and fourth MR elements change in an increasing/decreasing direction opposite to the first and third MR elements, depending on an external signal magnetic field.
    Type: Application
    Filed: July 27, 2010
    Publication date: February 3, 2011
    Applicant: TDK CORPORATION
    Inventors: Hiroshi YAMAZAKI, Hiraku HIRABAYASHI, Naoki OHTA
  • Patent number: 7858271
    Abstract: A method of measuring dimension of a first pattern with a narrow first width, and a second pattern with a second width wider than the first width of the first pattern and formed in a symmetrical appearance with respect to a center of the second pattern, the second pattern having edges opposed to each other defining the second width, includes a step of forming a pair of first dummy patterns each having a narrow width, the pair of first dummy patterns being spaced from the edges of the second pattern respectively by a distance approximate to the first width of the first pattern, a first measurement step of measuring, using a dimension measuring device, a spaced distance of one of the first dummy patterns from the edge of the second pattern and a width of the one of the first dummy patterns within the same field of view of the dimension measuring device, a second measurement step of measuring, using the dimension measuring device, a width of the first pattern under the same measurement condition as that of the f
    Type: Grant
    Filed: August 14, 2008
    Date of Patent: December 28, 2010
    Assignee: TDK Corporation
    Inventors: Tetsuya Hiraki, Naoki Ohta, Yoshiaki Tanaka
  • Patent number: 7817381
    Abstract: A thin film magnetic head comprises a lower magnetic shield layer and an upper magnetic shield layer which are mutually opposed in the layering direction, a magnetoresistance effect element having a free layer, and a bias-applying layer which applies a bias magnetic field to the magnetoresistance effect element. The free layer is positioned between the lower magnetic shield layer and the upper magnetic shield layer, and is positioned on the side of the media-opposed surface. The bias-applying layer has a first portion, a second portion, and a third portion. The first portion and the second portion are positioned at a distance in the track width direction so as to enclose the magnetoresistance effect element therebetween. The third portion is positioned either between the magnetoresistance effect element and the lower magnetic shield layer or between the magnetoresistance effect element and the upper magnetic shield layer, and connects the first portion and the second portion.
    Type: Grant
    Filed: May 16, 2007
    Date of Patent: October 19, 2010
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Kosuke Tanaka, Kazuki Sato
  • Patent number: 7801461
    Abstract: There is provided a charging member cleaning roller including: a core body; and an elastic layer that is provided on a peripheral surface of the core body and includes a polyurethane foam obtained from at least a polyester polyol, a foam stabilizer, and a catalyst. Moreover, there is provided a charging member cleaning roller including: a core body; and an elastic layer that is provided on a peripheral surface of the core body and includes a urethane foam having an open-cell structure, a resilience of approximately 15% to 30%, and a hardness of approximately 150N to 230N.
    Type: Grant
    Filed: February 16, 2007
    Date of Patent: September 21, 2010
    Assignee: Fuji Xerox Co., Ltd.
    Inventors: Takuro Hoshio, Fumio Ojima, Yoshihiro Maekawa, Taichi Yamada, Nagahito Ichijo, Naoki Ohta, Hiroyuki Fukuda, Yoshinori Kubo
  • Patent number: 7780344
    Abstract: The estimation method of the invention for estimating the deteriorations of a magneto-resistive effect device by heat shocks involves applying heat shocks by laser irradiation to a structure including a thin-film magnetic head comprising a magneto-resistive effect device to propagate them to the magneto-resistive effect device, thereby causing the deteriorations of the magneto-resistive effect device. Thus, (1) the deterioration mode phenomenon of “local overheating plus vibration” can be imitated in a simple yet very approximate state so that a device likely to undergo characteristics deteriorations due to the thermal asperity problem can be detected early at an initial fabrication process stage, and (2) what specifications a head device structure less likely to offer the thermal asperity problem is in can be judged at a product development stage.
    Type: Grant
    Filed: September 25, 2007
    Date of Patent: August 24, 2010
    Assignee: TDK Corporation
    Inventors: Takumi Yanagisawa, Naoki Ohta, Yosuke Antoku
  • Publication number: 20100202088
    Abstract: The invention is devised to provide a magnetoresistive element that is hardly susceptible to harmful influence of unnecessary magnetic fields and noise of heat even when reduction in size is achieved to be adaptable to higher recording density, and therefore that is excellent in operational reliability. The magnetoresistive element includes a stacked structure including, in order: a magnetically pinned layer whose magnetization direction is fixed in a given direction; a non-magnetic layer; a magnetically free layer whose magnetization direction changes according to an external magnetic field; and an antiferromagnetic bias layer exchange-coupled with the magnetically free layer. The exchange-coupling magnetic field between the magnetically free layer and the antiferromagnetic bias layer is smaller than a saturation magnetic field of the magnetically free layer.
    Type: Application
    Filed: February 6, 2009
    Publication date: August 12, 2010
    Applicant: TDK CORPORATION
    Inventors: Naoki Ohta, Hiroshi Yamazaki, Kosuke Tanaka, Takayasu Kanaya, Kei Hirata
  • Patent number: 7770284
    Abstract: A manufacturing method of an MR element in which current flows in a direction perpendicular to layer planes, includes forming on a lower electrode layer an MR multi-layered film having a cap layer at a top thereof, forming a mask on the cap layer of the MR multi-layered film, patterning the MR multi-layered film by milling through the mask to form an MR multi-layered structure, forming a magnetic domain control bias layer by using a lift off method using the mask, after forming the magnetic domain control bias layer, forming an additional cap layer on the cap layer and a part of the magnetic domain control bias layer, planarizing a top surface of the additional cap layer and the magnetic domain control bias layer, and forming an upper electrode layer on the planarized top surface.
    Type: Grant
    Filed: May 30, 2007
    Date of Patent: August 10, 2010
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Takeo Kagami
  • Patent number: 7743666
    Abstract: A tunneling effect element, including an insulating layer that forms a tunneling barrier, a lower electrode that is conductive and non-magnetic, and is formed on a bottom surface of said insulating layer, an upper electrode that is conductive and non-magnetic, and is formed on a top surface of said insulating layer, and a transmission member. The transmission member is made of insulating material that is formed surrounding the insulating layer and the lower and upper electrodes. The transmission member is also formed on a surface of an object to be detected, and transmits deformation of the object to be detected to the insulating layer. The tunneling effect element detects a change in stress of the object to be detected as a change in electric resistance.
    Type: Grant
    Filed: March 27, 2006
    Date of Patent: June 29, 2010
    Assignee: TDK Corporation
    Inventors: Tetsuya Kuwashima, Naoki Ohta
  • Patent number: 7742260
    Abstract: A magnetic head assembly includes a magnetic head slider with an element-formed surface on which at least one MR read head element is formed, an ABS to be opposed in operation to a magnetic recording medium and a fixing surface that is the other side of the ABS, and a support for supporting the magnetic head slider. The fixing surface of the magnetic head slider is fixed to the support by at least cure-shrinkage resin material layer providing a contractive force when cured. The cure-shrinkage resin material layer has at least one strip-shaped pattern running along a track width direction.
    Type: Grant
    Filed: August 31, 2006
    Date of Patent: June 22, 2010
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Nozomu Hachisuka
  • Publication number: 20100146774
    Abstract: A method of lapping a magnetic head slider includes a step of lapping a lapping surface of a row bar provided with a plurality of MR read head elements arranged along at least one line, a step of obtaining at least one output signal from at least one of the plurality of MR read head elements of the row bar during lapping, the at least one output signal corresponding to element resistance, a step of detecting at least one peak value of the obtained at least one output signal, and a step of controlling an amount of lapping of the row bar depending upon the detected at least one peak value.
    Type: Application
    Filed: December 11, 2008
    Publication date: June 17, 2010
    Applicant: TDK Corporation
    Inventors: Naoki Ohta, Takeo Kagami
  • Patent number: 7715155
    Abstract: A thin-film magnetic head includes a lower magnetic shield layer, an MR multi-layered structure formed on the lower magnetic shield layer so that current flows in a direction perpendicular to surfaces of laminated layers, an insulation layer formed to surround the MR multi-layered structure, an additional metal layer laminated on at least the MR multi-layered structure, an upper electrode layer made of a soft magnetic material laminated on the additional metal layer and the insulation layer, and an upper magnetic shield layer laminated on the upper electrode layer. The additional metal layer has a multi-layered structure including a nonmagnetic metal layer and a soft magnetic layer laminated on the nonmagnetic metal layer, and has a length along a track-width direction of the MR multi-layered structure larger than a width of a magnetization-free layer in the MR effect multi-layered structure.
    Type: Grant
    Filed: April 11, 2007
    Date of Patent: May 11, 2010
    Assignee: TDK Corporation
    Inventors: Takeo Kagami, Kazuki Sato, Kosuke Tanaka, Takayasu Kanaya, Naoki Ohta
  • Publication number: 20100104316
    Abstract: An electrostatic charging member includes a base material; and an outermost layer that contains a porous filler and a resin and has a gel fraction of at least about 50% and a surface roughness Rz in a range of about 2 ?m to about 20 ?m.
    Type: Application
    Filed: April 16, 2009
    Publication date: April 29, 2010
    Applicant: FUJI XEROX CO., LTD.
    Inventors: Takuro HOSHIO, Noboru WADA, Makoto TAKEMOTO, Nagahito ICHIJO, Naoki OHTA, Kenji INOUE, Hiroyuki MIURA, Keiko ONO, Taketoshi HOSHIZAKI, Minoru ROKUTAN