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: 7450349
    Abstract: Embodiments of the invention avoid erasure of recorded data by concentrating stray fields on a magnetic head element. According to one embodiment, in a magnetic storage apparatus using a perpendicular recording medium with a soft magnetic under layer, a soft magnetic shield is provided so as to surround the upper parts and sides of magnetic head elements. A distance between the soft magnetic shield and the medium is shorter than that between the soft magnetic shield and the magnetic head element.
    Type: Grant
    Filed: December 2, 2005
    Date of Patent: November 11, 2008
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Yasutaka Nishida, Ikuya Tagawa, Masafumi Mochizuki, Roger Wood
  • Patent number: 7428115
    Abstract: Embodiments of the invention provide a countermeasure against spike noise maintaining the data reliability of a magnetic recording layer. In one embodiment, the magnetic domain state right below and around the read head of the soft magnetic layer in the recording medium is locally and temporarily equalized using the write head, whereby, the effect of the spike noise caused by the magnetic domain boundaries (magnetic domain walls) of the soft magnetic layer on the read waveform is prevented. The read retry action of the magnetic hard disk drive is used as the trigger for the timing of the magnetic field application, thereby shortening the time for the magnetic field application.
    Type: Grant
    Filed: April 11, 2005
    Date of Patent: September 23, 2008
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Takeshi Nakagawa, Ikuya Tagawa, Atsushi Kikugawa
  • Patent number: 7408738
    Abstract: Embodiments of the invention efficiently improve the stray field robustness without changing the size or weight of the drive on a large scale. Because a stray field concentrates on a magnetic field element, a symptom in which already recorded data is erased is prevented. According to one embodiment, in a magnetic recording system that uses a perpendicular recording medium having a soft magnetic under layer, a soft magnetic shield is provided on an upper part and a side of a slider on which a magnetic head is mounted, and a distance C between the shield and the medium is made smaller than a distance A or B between the shield and the slider.
    Type: Grant
    Filed: April 12, 2005
    Date of Patent: August 5, 2008
    Assignee: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Yasutaka Nishida, Ikuya Tagawa, Toshihiko Shimizu
  • Publication number: 20080043358
    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: Application
    Filed: August 3, 2007
    Publication date: February 21, 2008
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Takeshi Nakagawa, Yasutaka Nishida, Ikuya Tagawa
  • Publication number: 20060250716
    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: Application
    Filed: May 3, 2006
    Publication date: November 9, 2006
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Syuji Nishida, Ikuya Tagawa, Yasutaka Nishida, Satoshi Tabata
  • Publication number: 20060139815
    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: Application
    Filed: December 22, 2005
    Publication date: June 29, 2006
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Syuji Nishida, Yasutaka Nishida, Ikuya Tagawa
  • Publication number: 20060119984
    Abstract: Embodiments of the invention avoid erasure of recorded data by concentrating stray fields on a magnetic head element. According to one embodiment, in a magnetic storage apparatus using a perpendicular recording medium with a soft magnetic under layer, a soft magnetic shield is provided so as to surround the upper parts and sides of magnetic head elements. A distance between the soft magnetic shield and the medium is shorter than that between the soft magnetic shield and the magnetic head element.
    Type: Application
    Filed: December 2, 2005
    Publication date: June 8, 2006
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Yasutaka Nishida, Ikuya Tagawa, Masafumi Mochizuki, Roger Wood
  • Publication number: 20060092556
    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: Application
    Filed: October 28, 2005
    Publication date: May 4, 2006
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Takehiko Hamaguchi, Yoshihisa Kamo, Hideaki Maeda, Yukiya Shimizu, Ikuya Tagawa, Tetsuo Yuki
  • Patent number: 7016149
    Abstract: According to the present invention, a recording magnetic head suitable for increasing a surface recording density and having a large recording magnetic field and a small recording blur is provided. A lower magnetic pole layer and an upper magnetic pole layer opposing the lower magnetic pole layer are formed, and a lower sub magnetic pole composed of a plurality of magnetic layers is formed along a medium facing face on the lower magnetic pole layer. The lengths in a direction perpendicular to the medium facing face of the respective magnetic layers forming the lower sub magnetic pole are longer as the respective magnetic layers get further away from the upper magnetic pole layer.
    Type: Grant
    Filed: November 6, 2002
    Date of Patent: March 21, 2006
    Assignee: Fujitsu Limited
    Inventors: Tomoko Kutsuzawa, Ikuya Tagawa
  • Patent number: 6970324
    Abstract: A soft magnetic film includes a ferromagnetic layer. The ferromagnetic layer is laid over a non-magnetic substructure including ferromagnetic atoms. The uniaxial magnetic anisotropy may be established in the ferromagnetic layer. Since a magnetic property is not required in the substructure under the ferromagnetic layer, the soft magnetic film of this type may be utilized for purposes of wider variations.
    Type: Grant
    Filed: November 19, 2002
    Date of Patent: November 29, 2005
    Assignee: Fujitsu Limited
    Inventors: Shoji Ikeda, Takayuki Kubomiya, Ikuya Tagawa, Yuji Uehara
  • Publication number: 20050233177
    Abstract: Embodiments of the invention provide a countermeasure against spike noise maintaining the data reliability of a magnetic recording layer. In one embodiment, the magnetic domain state right below and around the read head of the soft magnetic layer in the recording medium is locally and temporarily equalized using the write head, whereby, the effect of the spike noise caused by the magnetic domain boundaries (magnetic domain walls) of the soft magnetic layer on the read waveform is prevented. The read retry action of the magnetic hard disk drive is used as the trigger for the timing of the magnetic field application, thereby shortening the time for the magnetic field application.
    Type: Application
    Filed: April 11, 2005
    Publication date: October 20, 2005
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Takeshi Nakagawa, Ikuya Tagawa, Atsushi Kikugawa
  • Publication number: 20050225895
    Abstract: Embodiments of the invention efficiently improve the stray field robustness without changing the size or weight of the drive on a large scale. Because a stray field concentrates on a magnetic field element, a symptom in which already recorded data is erased is prevented. According to one embodiment, in a magnetic recording system that uses a perpendicular recording medium having a soft magnetic under layer, a soft magnetic shield is provided on an upper part and a side of a slider on which a magnetic head is mounted, and a distance C between the shield and the medium is made smaller than a distance A or B between the shield and the slider.
    Type: Application
    Filed: April 12, 2005
    Publication date: October 13, 2005
    Applicant: Hitachi Global Storage Technologies Netherlands B.V.
    Inventors: Yasutaka Nishida, Ikuya Tagawa, Toshihiko Shimizu
  • Publication number: 20050175864
    Abstract: The present invention relates to a magnetic thin film, which has high saturation magnetic flux density Bs of 2.2T or more, which is formed into a flat surface having surface roughness of 5 nm or less and which is capable of preferably being used for a write-head, and a magnetic head. The magnetic thin film includes a FeCo-based alloy layer stacked with a different layer so as to obtain the surface roughness of 5 nm or less. When forming the FeCo-based alloy layer, it is possible to flatten the film surface by performing reactive spattering using a reaction gas such as N2 for each of the layers forming the multi-layered thin film.
    Type: Application
    Filed: March 4, 2005
    Publication date: August 11, 2005
    Applicant: Fujitsu Limited
    Inventors: Shoji Ikeda, Takayuki Kubomiya, Masaaki Matsuoka, Ikuya Tagawa, Junichi Kane, Akifumi Chikazawa, Kazumasa Hosono
  • Publication number: 20050135006
    Abstract: A magnetic head increases the magnetic field strength just below a write gap 14 and thereby improves the recording resolution of a medium. To do so, an upper magnetic pole 10 and a lower magnetic pole 12 are disposed facing one another with the write gap 14 in between, with an end surface of the lower magnetic pole 12 being I-shaped and an end surface of the upper magnetic pole being T-shaped due to the upper magnetic pole 10 being formed of a first upper magnetic pole 10a that is disposed facing the lower magnetic pole 12 and is formed in an I shape that is shorter than the lower magnetic pole 12 and a second upper magnetic pole 10b that is joined to the first upper magnetic pole 10a and is formed wider than the first upper magnetic pole 10a.
    Type: Application
    Filed: February 22, 2005
    Publication date: June 23, 2005
    Inventors: Ikuya Tagawa, Hideyuki Akimoto, Tomoko Kutsuzawa, Syuji Nishida
  • Patent number: 6876524
    Abstract: A magnetoresistive transducer includes a magnetoresistive (MR) film interposed between domain control layers along the surface of a lower non-magnetic gap layer. Lead layers are formed on the domain control layers. An upper non-magnetic gap layer and an upper shield layer are sequentially formed to extend over the MR film and the lead layers. The upper shield layer is opposed to the surfaces of the MR element and the lead layers at a flat boundary or interface. The residual magnetization is supposed to exist in the upper shield layer in the direction of the magnetization established in the domain control layers after the upper shield layer has been subjected to the applied magnetic field for the magnetization of the domain control layers. The residual magnetization can be kept continuous along the flat interface of the upper shield layer. Any magnetic poles are hardly generated along the interface of the upper shield layer.
    Type: Grant
    Filed: March 14, 2001
    Date of Patent: April 5, 2005
    Assignee: Fujitsu Limited
    Inventors: Ikuya Tagawa, Kenichiro Yamada
  • Patent number: 6828046
    Abstract: A soft magnetic film comprising Fe, Co, a metallic element (M), and oxygen (O) is provided. The soft magnetic film is represented by a composition formula of (Fe1-aCoa)xMyOz. The metallic element (M) is one selected from a group consisting of Al, B, Ga, Si, Ge, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Rh, Ru, Ni, Pd and Pt, or is an alloy composed of at least two selected from this group. The composition formula fulfills the following conditions: a=0.05-0.65; y=0.2-9 at %, z=1-12 at %, and y+z=<15 at %; and x=(100−y−z) at %. A crystal structure is formed by having a bcc phase as a principal phase. The bcc phase has a crystal grain not exceeding 50 nm in diameter. The bcc phase includes a solid solution of the metallic element (M) and the oxygen (O).
    Type: Grant
    Filed: September 21, 2001
    Date of Patent: December 7, 2004
    Assignee: Fujitsu Limited
    Inventors: Shoji Ikeda, Ikuya Tagawa, Yuji Uehara, Yoshinori Ohtsuka
  • Patent number: 6822831
    Abstract: An object of the present invention is to provide a recording head having a magnetic pole simultaneously possessing a high saturation magnetic flux density, a high permeability and a high electric resistivity, and the magnetic pole of the recording head is a polycrystalline film comprising Fe whose content is not less than 57.5 atomic % and not more than 94.5 atomic %; one or more kinds of elements selected from the element group of Al, B, Ga, Si, Ge, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Rh, whose whole content is not less than 1 atomic % and not more than 15 atomic %; N whose content is not less than 0.5 atomic % and not more than 10 atomic %; and O whose content is not less than 1.5 atomic % and not more than 22.5 atomic %.
    Type: Grant
    Filed: February 12, 2002
    Date of Patent: November 23, 2004
    Assignee: Fujitsu Limited
    Inventors: Shoji Ikeda, Yuji Uehara, Ikuya Tagawa, Naoki Takeguchi, Masahiro Kakehi
  • Patent number: 6813824
    Abstract: A liquid resist is introduced between adjacent conductive lines of a coil pattern girdling around a magnetic core piece. When the liquid resist is cured, an insulating resin filler can be fixed between the adjacent conductive lines of the coil pattern. An insulating metallic layer is formed to extend over the insulting resin filler and the conductive lines of the coil pattern. Thereafter, the insulating metallic layer is subjected to a flattening grinding treatment until at least a part of the conductive line is exposed at a flattened surface. Of the resist, of a higher fluidity, penetrates in every hole and corner between the adjacent conductive lines, the gap defined between the adjacent conductive lines is fully filled with the insulating material. No voids remain in the gap. The conductive line of the coil can be reliably prevented from corrosion or oxidation. Moreover, a relatively brittle of fragile insulating resin filler is reliably prevented from being subjected to the flattening.
    Type: Grant
    Filed: December 23, 2002
    Date of Patent: November 9, 2004
    Assignee: Fujitsu Limited
    Inventors: Minoru Hasegawa, Yoshinori Ohtsuka, Yuji Uehara, Takashi Sekikawa, Hiroshi Maeda, Masahiro Kakehi, Ikuya Tagawa, Tomoko Kutsuzawa, Syuji Nishida
  • Patent number: 6751052
    Abstract: A thin film magnetic head includes an upper and a lower magnetic pole layer extending forward from a central magnetic core within a thin film coil. A narrow upper and lower front magnetic pole piece are connected to the front ends of the upper and lower magnetic pole layer, respectively. The upper front magnetic pole piece extends rearward from its front end exposed at a medium-opposed surface. The lower front magnetic pole piece extends in a lateral direction along the medium-opposed surface by a lateral width larger than that of the upper front magnetic pole piece. The lower front magnetic pole piece extends rearward from the medium-opposed surface by a longitudinal length smaller than that of the upper front magnetic pole piece. The lower front magnetic pole piece serves to concentrate the magnetic flux at the front ends of the upper and lower front magnetic pole pieces.
    Type: Grant
    Filed: July 6, 2000
    Date of Patent: June 15, 2004
    Assignee: Fujitsu Limited
    Inventors: Ikuya Tagawa, Tomoko Kutsuzawa, Syuji Nishida, Teruo Kiyomiya, Yoshinori Ohtsuka, Hiroshi Maeda, Minoru Hasegawa, Masahiro Kakehi, Takashi Sekikawa, Yukinori Ikegawa
  • Patent number: 6720075
    Abstract: A magnetic recording medium stable against heat of which high density recording can be attained is provided by employing a magnetic material such that coercive magnetic force in a recording magnetic layer increases with temperature rise. The magnetic recording medium is one in which the recording magnetic layer in which magnetic recording is carried out comprises an N-type Ferrimagnetic material, and compensation temperature of this N-type Ferrimagnetic material is made to be higher than an operating temperature range in which the magnetic recording medium is used.
    Type: Grant
    Filed: March 13, 2002
    Date of Patent: April 13, 2004
    Assignee: Fujitsu Limited
    Inventors: Ikuya Tagawa, Koji Matsumoto