Patents by Inventor Ikuya Tagawa

Ikuya Tagawa 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: 10283146
    Abstract: According to one embodiment, a system includes a head, where the head includes: an optical signal source configured to emit a first optical signal, and a near-field transducer (NFT) configured to focus the first optical signal on a moving ferroelectric storage medium positioned below the head. The system also includes a detector operatively coupled to the head, where the detector is configured to detect a second optical signal generated in and reflected from the ferroelectric storage medium, and where the second optical signal has twice the optical frequency as the first optical signal.
    Type: Grant
    Filed: April 3, 2018
    Date of Patent: May 7, 2019
    Assignee: Western Digital Technologies, Inc.
    Inventors: Takuya Matsumoto, Barry C. Stipe, Ikuya Tagawa, Roger W. Wood
  • Publication number: 20180350397
    Abstract: According to one embodiment, a system includes a head, where the head includes: an optical signal source configured to emit a first optical signal, and a near-field transducer (NFT) configured to focus the first optical signal on a moving ferroelectric storage medium positioned below the head. The system also includes a detector operatively coupled to the head, where the detector is configured to detect a second optical signal generated in and reflected from the ferroelectric storage medium, and where the second optical signal has twice the optical frequency as the first optical signal.
    Type: Application
    Filed: April 3, 2018
    Publication date: December 6, 2018
    Inventors: Takuya Matsumoto, Barry C. Stipe, Ikuya Tagawa, Roger W. Wood
  • Patent number: 9355668
    Abstract: A hard-disk drive having a structurally efficient magnetic head slider utilizes a MAMR-based spin torque oscillator (STO) for head-disk contact detection and for flying height sensing. Contact detection and spacing estimation techniques consider the nominal temperature difference, and thus different criteria, between read and write operations.
    Type: Grant
    Filed: May 21, 2013
    Date of Patent: May 31, 2016
    Assignee: HGST Netherlands B.V.
    Inventors: Yasutaka Nishida, Masato Shiimoto, Hiroyuki Katada, Ikuya Tagawa, Junguo Xu
  • Publication number: 20150109699
    Abstract: In accordance with one embodiment, a magnetic head includes a main pole configured to emit a recording magnetic field for affecting a magnetic medium, spin torque oscillator (STO) device in electrical communication with and positioned above the main pole in a track direction, the STO device being configured to generate a high-frequency magnetic field which is superimposed with the recording magnetic field in order to record data to the magnetic medium when current flows to the STO device, and a heat sink positioned near the STO device, the heat sink being configured to reduce a temperature of the STO device when current flows to the STO device. In another embodiment, a method includes forming a heat sink behind a STO device in an element height direction perpendicular to a media facing surface, and/or on both sides of the STO device in a cross-track direction at the media facing surface.
    Type: Application
    Filed: October 22, 2013
    Publication date: April 23, 2015
    Applicant: HGST Netherlands B.V.
    Inventors: Carl Boone, Jianhua Li, Isao Nunokawa, Erhard Schreck, Mikito Sugiyama, Ikuya Tagawa, Yuta Udo
  • Patent number: 8995088
    Abstract: In accordance with one embodiment, a magnetic head includes a main pole configured to emit a recording magnetic field for affecting a magnetic medium, a spin torque oscillator (STO) device in electrical communication with and positioned above the main pole in a track direction, the STO device being configured to generate a high-frequency magnetic field which is superimposed with the recording magnetic field in order to record data to the magnetic medium when current flows to the STO device, and a heat sink positioned near the STO device, the heat sink being configured to reduce a temperature of the STO device when current flows to the STO device. In another embodiment, a method includes forming a heat sink behind a STO device in an element height direction perpendicular to a media facing surface, and/or on both sides of the STO device in a cross-track direction at the media facing surface.
    Type: Grant
    Filed: October 22, 2013
    Date of Patent: March 31, 2015
    Assignee: HGST Netherlands B.V.
    Inventors: Carl Boone, Jianhua Li, Isao Nunokawa, Erhard Schreck, Mikito Sugiyama, Ikuya Tagawa, Yuta Udo
  • Patent number: 8917465
    Abstract: A method, apparatus, and system are provided for implementing a power-on spin-torque oscillator (STO) oscillation checker to monitor STO resistance to identify STO oscillation with microwave assisted magnetic recording (MAMR) hard disk drives (HDDs). A changing bias current is applied to the STO in the presence of constant write drive current. The STO bias current is changed to observe sudden changes in STO resistance monitored using a differentiator circuit to identify STO oscillation, used to ensure stable MAMR HDD write operation.
    Type: Grant
    Filed: June 26, 2014
    Date of Patent: December 23, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: John Contreras, Samir Y. Garzon, Ikuya Tagawa, Rehan Ahmed Zakai
  • Publication number: 20140347969
    Abstract: A hard-disk drive having a structurally efficient magnetic head slider utilizes a MAMR-based spin torque oscillator (STO) for head-disk contact detection and for flying height sensing. Contact detection and spacing estimation techniques consider the nominal temperature difference, and thus different criteria, between read and write operations.
    Type: Application
    Filed: May 21, 2013
    Publication date: November 27, 2014
    Applicant: HGST Netherlands B.V.
    Inventors: Yasutaka Nishida, Masato Shiimoto, Hiroyuki Katada, Ikuya Tagawa, Junguo Xu
  • Patent number: 8848317
    Abstract: A magnetic disk drive system configured for shingled magnetic data recording wherein data tracks are recorded in an overlapping fashion on a magnetic media. The disk drive system includes magnetic write heads that are asymmetric so as to have increased writing at one side of the write head. The magnetic disk drive system includes magnetic write heads that are mirror images of one another so that write heads located at opposite surfaces of the magnetic media (e.g. one head facing up and one facing down) end up having preferential writing in the location relative to inner and outer diameters of the magnetic media.
    Type: Grant
    Filed: December 21, 2012
    Date of Patent: September 30, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: Masato Shiimoto, Ikuya Tagawa, Yasutaka Nishida, Hiroyuki Katada
  • Publication number: 20140177105
    Abstract: A magnetic disk drive system configured for shingled magnetic data recording wherein data tracks are recorded in an overlapping fashion on a magnetic media. The disk drive system includes magnetic write heads that are asymmetric so as to have increased writing at one side of the write head. The magnetic disk drive system includes magnetic write heads that are mirror images of one another so that write heads located at opposite surfaces of the magnetic media (e.g. one head facing up and one facing down) end up having preferential writing in the location relative to inner and outer diameters of the magnetic media.
    Type: Application
    Filed: December 21, 2012
    Publication date: June 26, 2014
    Applicant: HGST Netherlands B.V.
    Inventors: Masato Shiimoto, Ikuya Tagawa, Yasutaka Nishida, Hiroyuki Katada
  • Patent number: 8760779
    Abstract: In one embodiment, a system includes a medium, a magnetic head having a write element adapted for writing data to the medium, a MAMR element and/or a TAMR element adapted for assisting recording on the medium, the MAMR element having a microwave-generating portion that receives current for operation thereof, the TAMR element having a localized heat-generating portion that receives current for operation thereof, and a read element adapted for reading data from the medium, a device adapted for measuring environmental conditions relating to the TAMR/MAMR elements and the medium, and a controller adapted for controlling operation of the magnetic head and adjusting operating parameters of the system based on the environmental conditions. The environmental conditions include temperature, a reproduced signal of the read element, and/or clearance between the TAMR/MAMR elements and the medium. The operating parameters include the clearance, amount of current injected to the TAMR/MAMR elements, and/or write current.
    Type: Grant
    Filed: December 30, 2011
    Date of Patent: June 24, 2014
    Assignee: HGST Netherlands B.V.
    Inventors: William D. Johns, David L. Whitaker, Ikuya Tagawa, Yoshihiro Shiroishi
  • Patent number: 8643972
    Abstract: A magnetic storage apparatus includes a magnetic recording medium, a microwave assisted magnetic recording head at least equipped with a magnetic recording pole that generates a recording magnetic field for writing to the magnetic recording medium and a high-frequency oscillator that generates a high-frequency field, a magnetic reproducing head that reads information from the magnetic recording medium, a signal processing unit that processes a signal written by the magnetic recording head and a signal read by the magnetic reproducing head and a unit that controls clearance between the high-frequency oscillator and the magnetic recording medium. The magnetic storage apparatus has a characteristic that the high-frequency oscillator is not operated except in recording.
    Type: Grant
    Filed: February 22, 2012
    Date of Patent: February 4, 2014
    Assignee: Hitachi, Ltd.
    Inventors: Yoshihiro Shiroishi, Hiroshi Fukuda, Ikuya Tagawa, Tomohiro Okada
  • Patent number: 8570684
    Abstract: A method, apparatus, and system for implementing spin integrated spin-torque oscillator (STO) with an interface bias control for hard disk drives. Bias circuitry for a spin-torque oscillator (STO) is integrated with a slider for microwave assisted magnetic recording (MAMR). The slider includes read and write transducers and the integrated STO bias circuitry controls a bias potential applied to a write return pole to the write transducer with respect to a disk.
    Type: Grant
    Filed: October 5, 2012
    Date of Patent: October 29, 2013
    Assignee: HGST Netherlands B.V.
    Inventors: John Thomas Contreras, Ikuya Tagawa, Albert John Wallash
  • Patent number: 8553507
    Abstract: In one embodiment, a magnetic data storage system includes a magnetic disk medium, a microwave-assisted magnetic recording (MAMR) head including a main pole adapted for recording data to the magnetic disk medium having a first recording width, a spin torque oscillator (STO) adapted to apply a high-frequency magnetic field to the magnetic disk medium during a recording operation, wherein the STO is operable or inoperable when in an on or off state, respectively, wherein the main pole has a second recording width when the STO is in the on state, and the second recording width is different from the first recording width, a drive mechanism for passing the magnetic disk medium over the MAMR head, a read head including a magnetoresistance sensor, and a controller adapted for adjusting a shift quantity of the magnetic head depending on whether the STO is in the on or off state.
    Type: Grant
    Filed: November 13, 2012
    Date of Patent: October 8, 2013
    Assignee: HGST Netherlands B.V.
    Inventors: Ikuya Tagawa, Masaomi Ikeda
  • Publication number: 20130170060
    Abstract: In one embodiment, a system includes a medium, a magnetic head having a write element adapted for writing data to the medium, a MAMR element and/or a TAMR element adapted for assisting recording on the medium, the MAMR element having a microwave-generating portion that receives current for operation thereof, the TAMR element having a localized heat-generating portion that receives current for operation thereof, and a read element adapted for reading data from the medium, a device adapted for measuring environmental conditions relating to the TAMR/MAMR elements and the medium, and a controller adapted for controlling operation of the magnetic head and adjusting operating parameters of the system based on the environmental conditions. The environmental conditions include temperature, a reproduced signal of the read element, and/or clearance between the TAMR/MAMR elements and the medium. The operating parameters include the clearance, amount of current injected to the TAMR/MAMR elements, and/or write current.
    Type: Application
    Filed: December 30, 2011
    Publication date: July 4, 2013
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: William D. Johns, David L. Whitaker, JR., Ikuya Tagawa, Yoshihiro Shiroishi
  • Publication number: 20130083423
    Abstract: A magnetic storage apparatus includes a magnetic recording medium, a microwave assisted magnetic recording head at least equipped with a magnetic recording pole that generates a recording magnetic field for writing to the magnetic recording medium and a high-frequency oscillator that generates a high-frequency field, a magnetic reproducing head that reads information from the magnetic recording medium, a signal processing unit that processes a signal written by the magnetic recording head and a signal read by the magnetic reproducing head and a unit that controls clearance between the high-frequency oscillator and the magnetic recording medium. The magnetic storage apparatus has a characteristic that the high-frequency oscillator is not operated except in recording.
    Type: Application
    Filed: February 22, 2012
    Publication date: April 4, 2013
    Inventors: Yoshihiro Shiroishi, Hiroshi Fukuda, Ikuya Tagawa, Tomohiro Okada
  • Publication number: 20110141616
    Abstract: In one embodiment, a magnetic recording head includes a main magnetic pole adapted for generating a magnetic field for recording information on a magnetic disk, a magnetic shield member adapted for suppressing spreading of a magnetic field output from the main magnetic pole through a non-magnetic insulation member, a side top gap, a side bottom gap, and a trailing gap. The side top gap is less than two times the trailing gap, the side bottom gap is larger than the side top gap, and the magnetic shield member is positioned on a sliding surface of the magnetic recording head and includes a trailing portion positioned adjacent the trailing gap in the trailing direction and at least one side portion positioned adjacent the side bottom gap in the cross-track direction. Other heads and systems are also presented according to various embodiments.
    Type: Application
    Filed: December 10, 2010
    Publication date: June 16, 2011
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Ikuya Tagawa, Masafumi Mochizuki, Yohji Maruyama
  • Patent number: 7830631
    Abstract: Embodiments of the present invention reduce lowering of a recording current and a recording magnetic field that might occur upon execution of write pre-compensation for compensating the NLTS according to a perpendicular magnetic recording method. According to one embodiment, the recording current overshoot is increased for recording a high NLTS recording data pattern. The read signal quality is improved, thereby a highly reliable magnetic disk can be provided.
    Type: Grant
    Filed: August 3, 2007
    Date of Patent: November 9, 2010
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Takeshi Nakagawa, Yasutaka Nishida, Ikuya Tagawa
  • Patent number: 7518825
    Abstract: Embodiments of the invention avoid loss of information as recorded, due to an external magnetic field applied. In one embodiment, a pole expanded part prone to occurrence of magnetic saturation is formed so as to prevent magnetic fluxes from being converged at ends of a return pole of a magnetic head.
    Type: Grant
    Filed: December 22, 2005
    Date of Patent: April 14, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Syuji Nishida, Yasutaka Nishida, Ikuya Tagawa
  • Patent number: 7486485
    Abstract: Embodiments of the invention prevent a decrease in magnetization or demagnetization from occurring to recording magnetization regardless of a direction in which a stray field is applied. In one embodiment, an apparatus for data storage system comprises a head having a magnetic field shield in the vicinity of a main pole, and a cover of the device, using a constituent material with a magnetic field shielding effect, across the cover, or at part thereof. When a stray field in a direction perpendicular to a recording medium is applied, the effect of the magnetic field is alleviated by the magnetic field shield installed in the vicinity of the main pole. In such a case, it need only be sufficient to form the magnetic field shield in a shape optimum for removing the stray field in the perpendicular direction only.
    Type: Grant
    Filed: October 28, 2005
    Date of Patent: February 3, 2009
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Takehiko Hamaguchi, Yoshihisa Kamo, Hideaki Maeda, Yukiya Shimizu, Ikuya Tagawa, Tetsuo Yuki
  • Patent number: 7468852
    Abstract: Embodiments of the invention improve efficiency in alternating-current demagnetization of a magnetic recording medium. In specific embodiments, magnet fields in a direction slanting to an easy direction of magnetization of recording layer magnetization of a medium in rotation are applied.
    Type: Grant
    Filed: May 3, 2006
    Date of Patent: December 23, 2008
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Syuji Nishida, Ikuya Tagawa, Yasutaka Nishida, Satoshi Tabata