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).

  • Publication number: 20100061023
    Abstract: A magnetic head device includes a magnetic head section having a first free layer with a magnetization orientation that is not previously defined but changes depending upon only external magnetic field applied, a second free layer with a magnetization orientation that is not previously defined but changes depending upon only external magnetic field applied, a nonmagnetic intermediate layer sandwiched between the first free layer and the second free layer, a first electrode layer stacked on a surface of the first free layer opposite to the nonmagnetic intermediate layer, and a second electrode layer stacked on a surface of the second free layer opposite to the nonmagnetic intermediate layer; a sense-current supply means for flowing a sense current across the first electrode layer and the second electrode layer of the magnetic head section; and a frequency divider circuit for dividing by two a frequency of an output signal produced across the first electrode layer and the second electrode layer of the magnetic
    Type: Application
    Filed: September 11, 2008
    Publication date: March 11, 2010
    Applicant: TDK Corporation
    Inventors: Naoki OHTA, Kei HIRATA
  • Publication number: 20100040957
    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 the pattern center, 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 first measure
    Type: Application
    Filed: August 14, 2008
    Publication date: February 18, 2010
    Applicant: TDK CORPORATION
    Inventors: Tetsuya HIRAKI, Naoki OHTA, Yoshiaki TANAKA
  • Patent number: 7652854
    Abstract: A tunneling magneto-resistive element includes: a tunneling magneto-resistive film including an antiferromagnetic layer, a pinned layer, a barrier layer and a free layer; and a lower magnetic shielding film disposed below the tunneling magneto-resistive film with respect to a lamination direction. The barrier layer is constituted of magnesium oxide. The lower magnetic shielding film has a multi-layer structure including a crystalline layer and an amorphous layer disposed above the crystalline layer with respect to the lamination direction. The crystalline layer contains at least one crystal grain having a grain size of 500 nm or more.
    Type: Grant
    Filed: August 8, 2006
    Date of Patent: January 26, 2010
    Assignee: TDK Corporation
    Inventors: Takeo Kagami, Naoki Ohta, Kazuki Sato, Satoshi Miura
  • Patent number: 7631416
    Abstract: A reticle having a convex portion and a concave portion is used to form a convex portion and concave portion in the resist pattern for magnetic detection element and conductive layer, respectively. Then, with each resist pattern as a mask, unnecessary portions are removed to determine an initial height and to form a convex portion and concave portion in the magnetic detection element layer and in the conductive layer, respectively. Then, based on a ratio between widths of the convex portion and of the concave portion of the magnetic detection element layer, a deviation of the magnetic detection element layer is obtained, and a deviation of the conductive layer is obtained in a similar way, and based on these deviations the medium facing surface is ground with the conductive layer as a resistance sensor so that the height of the magnetic detection element layer be a desired value.
    Type: Grant
    Filed: May 14, 2007
    Date of Patent: December 15, 2009
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Kazuki Sato
  • Publication number: 20090237833
    Abstract: Provided is a magnetic tape apparatus using perpendicular magnetic recording, which has the function corresponding to an soft-magnetic under layer with sufficiently large thickness and enables the magnetic tape to maintain life sufficiently. This magnetic tape apparatus comprises: a tape head comprising at least one write head element for perpendicular magnetic recording; and a soft-magnetic capstan belt having a surface contact with the magnetic tape and pressing the magnetic tape to the tape head at least during recording, for controlling running speed of the magnetic tape by causing the magnetic tape to run together with the soft-magnetic capstan belt. Further it is preferable that at least two capstan-belt axes are further provided, and the soft-magnetic capstan belt is a loop running among the at least two capstan-belt axes.
    Type: Application
    Filed: March 19, 2008
    Publication date: September 24, 2009
    Applicant: TDK CORPORATION
    Inventors: Hideaki SATO, Naoki OHTA, Hiraku HIRABAYASHI, Nozomu HACHISUKA, Noriaki KASAHARA
  • Publication number: 20090231762
    Abstract: An MR element includes a pinned layer, a free layer and a nonmagnetic space layer or a tunnel barrier layer sandwiched between the pinned layer and the free layer. A magnetization direction of the free layer is substantially perpendicular to a film surface thereof, and a magnetization direction of the pinned layer is substantially parallel to a film surface thereof.
    Type: Application
    Filed: March 13, 2008
    Publication date: September 17, 2009
    Applicant: TDK CORPORATION
    Inventors: Naoki Ohta, Satoshi Miura, Tomohito Mizuno
  • Patent number: 7583462
    Abstract: Timely and proper flying height adjustment is achieved using a controller, which is designed for a magnetic recording and reproducing apparatus that does not use a magnetic head having a heating element for flying height adjustment without any modification. A head amplifier includes a write amplifier for applying a write current to a write head element, a read amplifier for amplifying a read voltage output from a read head element and outputting a read signal, a heating element driver for applying a heat generating current to at least one heating element for adjusting a flying height, and a heat controller for controlling the heating element driver.
    Type: Grant
    Filed: September 6, 2007
    Date of Patent: September 1, 2009
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Tetsuya Kuwashima
  • Patent number: 7573675
    Abstract: A thin film magnetic head has an air bearing surface and comprises magnetic shield layers, an MR element, bias-applying layers, and a hard magnetic layer. Each of the magnetic shield layers has an end face forming the air bearing surface, and an end face located opposite to the end face. The MR element is located between the magnetic shield layers and on the end face side. The bias-applying layers are located between the magnetic shield layers and are arranged to apply a bias magnetic field to the MR element. The hard magnetic layer is located between the magnetic shield layers and on the end face side. A height of the hard magnetic layer is larger than ? and smaller than ½ of a height of each magnetic shield layer.
    Type: Grant
    Filed: March 14, 2006
    Date of Patent: August 11, 2009
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Kazuki Sato, Noriaki Kasahara, Takeo Kagami
  • Publication number: 20090190271
    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: Application
    Filed: January 28, 2008
    Publication date: July 30, 2009
    Applicant: TDK CORPORATION
    Inventors: Hiroshi Yamazaki, Naoki Ohta
  • Patent number: 7564653
    Abstract: A magnetic disk drive apparatus includes a magnetic disk, a ramp mechanism, a pair of magnetic head sliders each having an MR read head element, and a load/unload mechanism for retracting the pair of magnetic head sliders to the ramp mechanism under unloading states and for putting the pair of magnetic head sliders back to face front and back surfaces of the magnetic disk respectively under loading states. The ramp mechanism has head resting portions and a pair of permanent magnets. The pair of magnetic head sliders respectively resting in the head resting portions in a manner to face to each other during unloaded states. The pair of permanent magnets generates a closed loop magnetic field applied to the pair of magnetic head sliders rested in the respective head resting portions. The magnetic fields applied to the respective magnetic head sliders are in opposite directions along the track width of the magnetic head sliders.
    Type: Grant
    Filed: December 28, 2006
    Date of Patent: July 21, 2009
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Kazuki Sato
  • Publication number: 20090154024
    Abstract: Provided is a thin-film magnetic head for reading data from a magnetic recording medium and/or writing data to a magnetic recording medium, in which the magnetic spacing can be controlled appropriately by stably adjusting the pressure working between the thin-film magnetic head and the magnetic recording medium according to the change of conditions such as the change over time. This thin-film magnetic head comprises at least one through hole reaching a surface opposed to the magnetic recording medium of the thin-film magnetic head, for adjusting a pressure working between the thin-film magnetic head and the magnetic recording medium. Preferably, the head further comprises at least one flow-amount control means for controlling the flow amount of gas that flows via the at least one through hole.
    Type: Application
    Filed: December 17, 2007
    Publication date: June 18, 2009
    Applicant: TDK CORPORATION
    Inventors: Nozomu HACHISUKA, Naoki OHTA
  • Publication number: 20090145878
    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: Application
    Filed: December 11, 2007
    Publication date: June 11, 2009
    Applicant: TDK CORPORATION
    Inventors: Naoki Ohta, Kazuki Sato, Kosuke Tanaka
  • Publication number: 20090130491
    Abstract: A magnetoresistive element (MR element) for reading a change in a magnetic field of a magnetic recording medium includes first and second electrode layers for providing a sensing current, which are perpendicular to an air bearing surface (ABS) facing the magnetic recording medium, first and second free layers which have a magnetization direction which changes in accordance with an external magnetic field, and a spacer layer composed of non-magnetic material. A ratio of a representative width and a representative length of each of the first and second free layers is at least 2 to 1, to thereby provide initial magnetizations along a direction of the representative length of each of the first and second free layers.
    Type: Application
    Filed: November 15, 2007
    Publication date: May 21, 2009
    Applicant: TDK Corporation
    Inventors: Naoki Ohta, Hiroshi Yamazaki
  • Publication number: 20090109577
    Abstract: The invention provides a magneto-resistive effect device of the CPP structure comprising 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 the magnetizations of the first ferromagnetic layer and the second ferromagnetic layer are antiparallel with each other, wherein the 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.
    Type: Application
    Filed: October 25, 2007
    Publication date: April 30, 2009
    Applicant: TDK CORPORATION
    Inventors: Hiroshi Yamazaki, Naoki Ohta
  • Patent number: 7520165
    Abstract: Highly efficient and highly sensitive sensors of small size are provided in desired position, desired shape and size for a micro structure that causes elastic deformation at least a part thereof. Moreover, utilizing the sensors allows facilitating to assemble and adjust the components, miniaturizing and simplifying the detection circuit, and measuring a local displacement of a fine part of the micro structure. A micro structure is a cantilever in which a beam part causes elastic deformation. This cantilever includes a sensor detecting elastic deformation of a beam part by tunneling effect.
    Type: Grant
    Filed: June 7, 2006
    Date of Patent: April 21, 2009
    Assignee: TDK Corporation
    Inventors: Naoki Ohta, Tetsuya Kuwashima
  • Publication number: 20090080491
    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: Application
    Filed: September 25, 2007
    Publication date: March 26, 2009
    Applicant: TDK CORPORATION
    Inventors: Takumi Yanagisawa, Naoki Ohta, Yosuke Antoku
  • Patent number: 7489481
    Abstract: A magnetic head is provided for further improving a correlation between the dynamic characteristics and static characteristics. A lower magnetic shield layer, a magneto-resistive layer, and an upper magnetic shield layer are laminated on a base in this order. A lower lead layer and an upper lead layer apply a sense current to the magneto-resistive layer in a direction substantially perpendicular to the film plane thereof through the magnetic shield layers. The lower magnetic shield layer and upper magnetic shield layer have their shapes and sizes which substantially exactly overlap each other, when viewed in a laminating direction. The lower lead layer is electrically connected to the lower magnetic shield layer. At least a portion of the lower lead layer closer to the lower magnetic shield layer is made of a non-magnetic conductive material. The upper lead layer is electrically connected to the upper magnetic shield layer.
    Type: Grant
    Filed: February 28, 2005
    Date of Patent: February 10, 2009
    Assignee: TDK Corporation
    Inventors: Kentaro Nagai, Takeo Kagami, Noriaki Kasahara, Naoki Ohta, Satoshi Miura
  • Publication number: 20090034121
    Abstract: A magnetic head includes a medium facing surface, a coil, and a pole layer that generates a write magnetic field. The pole layer includes: a track width defining portion having a first end located in the medium facing surface and a second end opposite to the first end; and a wide portion connected to the second end. The first end defines the track width. The track width defining portion has a width taken in the track width direction, and the wide portion has a width taken in the track width direction that is greater than the width of the track width defining portion taken in the track width direction. The coil is helically wound only around the track width defining portion of the pole layer, and has a portion located between the medium facing surface and the wide portion.
    Type: Application
    Filed: July 30, 2007
    Publication date: February 5, 2009
    Applicant: TDK CORPORATION
    Inventors: Naoki Ohta, Kenkichi Anagawa
  • Publication number: 20080282532
    Abstract: As a reticle pattern corresponding to a resist pattern for magnetic detection element layer and a reticle pattern corresponding to a resist pattern for conductive layer in a reticle, a reticle having a convex portion that projects in the height direction and a concave portion that dents in the direction opposite to the convex portion, respectively, is used to form a convex portion and concave portion corresponding to the convex portion and concave portion of the reticle pattern in the resist pattern for magnetic detection element and in the resist pattern for conductive layer, respectively.
    Type: Application
    Filed: May 14, 2007
    Publication date: November 20, 2008
    Applicant: TDK CORPORATION
    Inventors: Naoki Ohta, Kazuki Sato
  • Publication number: 20080285178
    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: Application
    Filed: May 16, 2007
    Publication date: November 20, 2008
    Applicant: TDK CORPORATION
    Inventors: Naoki Ohta, Kosuke Tanaka, Kazuki Sato