Patents by Inventor Hajime Aoi

Hajime Aoi 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: 8691402
    Abstract: A perpendicular magnetic recording medium according to which both the thermal stability of the magnetization is good and writing with a magnetic head is easy, and moreover the SNR is improved. In the case of a perpendicular magnetic recording medium comprising a nonmagnetic substrate (1), and at least a nonmagnetic underlayer (2), a magnetic recording layer (3), and a protective layer (4) formed in this order on the nonmagnetic substrate (1), the magnetic recording layer (3) comprises a low Ku region (31) layer having a perpendicular magnetic anisotropy constant (Ku value) of not more than 1×105 erg/cm3, and a high Ku region (32) layer having a Ku value of at least 1×106 erg/cm3. Moreover, the magnetic recording layer (3) is made to have therein nonmagnetic grain boundaries that contain a nonmagnetic oxide and magnetically isolate crystal grains, which are made of a ferromagnetic metal, from one another.
    Type: Grant
    Filed: November 2, 2012
    Date of Patent: April 8, 2014
    Assignees: Fuji Electric Co., Ltd., National University Corporation Tohoku University
    Inventors: Osamu Kitakami, Yutaka Shimada, Satoshi Okamoto, Takehito Shimatsu, Hajime Aoi, Hiroaki Muraoka, Yoshihisa Nakamura, Hiroyuki Uwazumi, Tadaaki Oikawa
  • Patent number: 8323808
    Abstract: There is provided a perpendicular magnetic recording medium according to which both the thermal stability of the magnetization is good and writing with a magnetic head is easy, and moreover the SNR is improved. In the case of a perpendicular magnetic recording medium comprising a nonmagnetic substrate 1, and at least a nonmagnetic underlayer 2, a magnetic recording layer 3 and a protective layer 4 formed in this order on the nonmagnetic substrate 1, the magnetic recording layer 3 comprises a low Ku region 31 layer having a perpendicular magnetic anisotropy constant (Ku value) of not more than 1×105 erg/cm3, and a high Ku region 32 layer having a Ku value of at least 1×106 erg/cm3. Moreover, the magnetic recording layer 3 is made to have therein nonmagnetic grain boundaries that contain a nonmagnetic oxide and magnetically isolate crystal grains, which are made of a ferromagnetic metal, from one another.
    Type: Grant
    Filed: January 10, 2005
    Date of Patent: December 4, 2012
    Assignees: Fuji Electric Co., Ltd., National University Corporation Tohoku University
    Inventors: Osamu Kitakami, Yutaka Shimada, Satoshi Okamoto, Takehito Shimatsu, Hajime Aoi, Hiroaki Muraoka, Yoshihisa Nakamura, Hiroyuki Uwazumi, Tadaaki Oikawa
  • Patent number: 8076012
    Abstract: Disclosed are a magnetic thin film capable of providing a high uniaxial magnetic anisotropy, Ku, while suppressing the saturation magnetization Ms thereof, and a method for forming the film; and also disclosed are various devices to which the magnetic thin film is applied. The magnetic thin film comprises a Co-M-Pt alloy having an L11-type ordered structure (wherein M represents one or more metal elements except Co and Pt). For example, the Co-M-Pt alloy is a Co—Ni—Pt alloy of which the composition comprises from 10 to 35 at. % of Co, from 20 to 55 at. % of Ni and a balance of Pt. The magnetic thin film is applicable to perpendicular magnetic recording media, tunnel magneto-resistance (TMR) devices, magnetoresistive random access memories (MRAM), microelectromechanical system (MEMS) devices, etc.
    Type: Grant
    Filed: July 28, 2009
    Date of Patent: December 13, 2011
    Assignees: Tohoku University, Fuji Electric Co., Ltd.
    Inventors: Takehito Shimatsu, Hideo Sato, Osamu Kitakami, Satoshi Okamoto, Hajime Aoi, Hiroyasu Kataoka
  • Patent number: 7993762
    Abstract: The present invention relates to a magnetic thin film containing a L11 type Co—Pt—C alloy in which atoms are orderly arranged, and can realize an order degree excellent in regard to the L11 type Co—Pt—C alloy to achieve excellent magnetic anisotropy of the magnetic thin film. Therefore, in the various application devices using the magnetic thin film, it is possible to achieve a large capacity process and/or a high density process thereof in a high level.
    Type: Grant
    Filed: December 4, 2009
    Date of Patent: August 9, 2011
    Assignees: Tohoku University, Fuji Electric Device Technology Co., Ltd.
    Inventors: Takehito Shimatsu, Hideo Sato, Osamu Kitakami, Satoshi Okamoto, Hajime Aoi, Hiroyasu Kataoka
  • Publication number: 20110020669
    Abstract: A magnetic recording medium having excellent stability of recorded magnetic signals and capable of recording magnetic signals by a thermally assisted magnetic recording system in which a magnetic recording layer of the magnetic recording medium contains ferromagnetic crystal grains of a Co—Ni—Pt alloy with a Pt content of 44 at % or more and 55 at % or less and with an atom content ratio: Ni/(Co+Ni) of 0.64 or more and 0.8 or less. The magnetic recording medium has extremely excellent stability of recorded magnetic signals since the Co—Ni—Pt alloy constituting the magnetic recording layer has an extremely high anisotropy field at a normal temperature. Further, the magnetic recording medium can perform signal recording based on the thermally assisted magnetic recording system since the Co—Ni—Pt alloy constituting the magnetic recording layer has a Curie point within an appropriate temperature range.
    Type: Application
    Filed: July 21, 2010
    Publication date: January 27, 2011
    Inventors: Junichi SAYAMA, Hiroaki Nemoto, Hiroshi Ide, Hiroyasu Kataoka, Nobuyukl Takahashi, Takehito Shimatsu, Osamu Kitakami, Satoshi Okamoto, Hajime Aoi
  • Publication number: 20100140727
    Abstract: The present invention relates to a magnetic thin film containing a L11 type Co—Pt—C alloy in which atoms are orderly arranged, and can realize an order degree excellent in regard to the L11 type Co—Pt—C alloy to achieve excellent magnetic anisotropy of the magnetic thin film. Therefore, in the various application devices using the magnetic thin film, it is possible to achieve a large capacity process and/or a high density process thereof in a high level.
    Type: Application
    Filed: December 4, 2009
    Publication date: June 10, 2010
    Applicants: Tohoku University, Fuji Electric Device Technology Co., Ltd.
    Inventors: Takehito SHIMATSU, Hideo SATO, Osamu KITAKAMI, Satoshi OKAMOTO, Hajime AOI, Hiroyasu KATAOKA
  • Publication number: 20100055503
    Abstract: Disclosed are a magnetic thin film capable of providing a high uniaxial magnetic anisotropy, Ku, while suppressing the saturation magnetization Ms thereof, and a method for forming the film; and also disclosed are various devices to which the magnetic thin film is applied. The magnetic thin film comprises a Co-M-Pt alloy having an L11-type ordered structure (wherein M represents one or more metal elements except Co and Pt). For example, the Co-M-Pt alloy is a Co—Ni—Pt alloy of which the composition comprises from 10 to 35 at. % of Co, from 20 to 55 at. % of Ni and a balance of Pt. The magnetic thin film is applicable to perpendicular magnetic recording media, tunnel magneto-resistance (TMR) devices, magnetoresistive random access memories (MRAM), microelectromechanical system (MEMS) devices, etc.
    Type: Application
    Filed: July 28, 2009
    Publication date: March 4, 2010
    Applicants: TOHOKU UNIVERSITY, FUJI ELECTRIC DEVICE TECHNOLOGY CO., LTD.
    Inventors: Takehito SHIMATSU, Hideo SATO, Osamu KITAKAMI, Satoshi OKAMOTO, Hajime AOI, Hiroyasu KATAOKA
  • Publication number: 20050181237
    Abstract: There is provided a perpendicular magnetic recording medium according to which both the thermal stability of the magnetization is good and writing with a magnetic head is easy, and moreover the SNR is improved. In the case of a perpendicular magnetic recording medium comprising a nonmagnetic substratel, and at least a nonmagnetic underlayer 2, a magnetic recording layer 3 and a protective layer 4 formed in this order on the nonmagnetic substrate 1, the magnetic recording layer 3 comprises a low Ku region 31 layer having a perpendicular magnetic anisotropy constant (Ku value) of not more than 1×105 erg/cm3, and a high Ku region 32 layer having a Ku value of at least 1×106 erg/cm3. Moreover, the magnetic recording layer 3 is made to have therein nonmagnetic grain boundaries that contain a nonmagnetic oxide and magnetically isolate crystal grains, which are made of a ferromagnetic metal, from one another.
    Type: Application
    Filed: January 10, 2005
    Publication date: August 18, 2005
    Inventors: Osamu Kitakami, Yutaka Shimada, Satoshi Okamoto, Takehito Shimatsu, Hajime Aoi, Hiroaki Muraoka, Yoshihisa Nakamura, Hiroyuki Uwazumi, Tadaaki Oikawa
  • Publication number: 20040109253
    Abstract: A magnetic recording disk drive having an interline crosstalk amplitude detection unit 36 within its preamplifier 20 is provided. The detection unit 36 is used for detection coil malfunctions. The interline crosstalk amplitude detection unit 36 includes an interline crosstalk amplitude detection circuit 31 which is branched from a branch circuit 30 within the read circuit in the preamplifier 20. The interline crosstalk amplitude detection unit 36 is provided with the capability to determine occurrence of a write condition abnormality when the amplitude has exceeded a threshold value, making it possible to ensure the recording function of the preamplifier 20. Likewise, the inductance is reduced when a circulatory shunt has occurred in a line near the head, making it possible to detect a write condition abnormality.
    Type: Application
    Filed: September 30, 2003
    Publication date: June 10, 2004
    Applicant: Hitachi Global Storage Technologies Japan, Ltd.
    Inventors: Nobumasa Nishiyama, Mikio Suzuki, Masaki Yoshinaga, Yoichiro Kobayashi, Hajime Aoi
  • Patent number: 6243824
    Abstract: An array disk subsystem including a command selector for separating a signal from a host into a data item and a command, a data dividing unit for subdividing the data item, an ECC generator for producing an ECC for each of the obtained subdata items, a group of data disks for respectively storing thereon the subdata items and the ECCs, a command interpreting unit for interpreting the command, an I/O counter for counting I/O commands in the command, a backup processor for requesting a backup command based on count information of the I/O counter, and a backup unit responsive to the backup command for sequentially reading the subdata items and the ECCs from the data disks to record therein the subdata items and the ECCs.
    Type: Grant
    Filed: December 9, 1994
    Date of Patent: June 5, 2001
    Assignee: Hitachi, Ltd.
    Inventors: Hitoshi Kakuta, Yoshihisa Kamo, Hajime Aoi
  • Patent number: 6069762
    Abstract: In a magnetic recording drive having a plurality of magnetic heads each employing a magnetoresistive sensor for the purpose of averaging the time required for sense currents to be caused to flow through the respective magnetoresistive sensors to shorten the longest reproducing time and to suppress the degradation of the characteristics due to the electromigration, thereby improving the reliability of the magnetic recording drive, the magnetic recording drive includes circuits for averaging the useful life depending on the currents caused to flow through the respective magnetoresistive sensors among the plurality of magnetic heads, whereby the time required for the sense current to be caused to flow through one MR reproducing head is greatly shortened. Therefore, the levels of outputs of the MR reproducing heads can be increased without reduction of the reliability and thus the reliability of the magnetic recording drive can be improved.
    Type: Grant
    Filed: July 9, 1999
    Date of Patent: May 30, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Hajime Aoi, Toshiaki Tsuyoshi, Makoto Koizumi, Nobumasa Nishiyama, Yoshibumi Matsuda, Takuji Ogawa, Kazuhisa Shiraishi
  • Patent number: 6014275
    Abstract: In a magnetic recording drive having a plurality of magnetic heads each employing a magnetoresistive sensor for the purpose of averaging the time required for sense currents to be caused to flow through the respective magnetoresistive sensors to shorten the longest reproducing time and to suppress the degradation of the characteristics due to the electromigration, thereby improving the reliability of the magnetic recording drive, the magnetic recording drive includes circuits for averaging the useful life depending on the currents caused to flow through the respective magnetoresistive sensors among the plurality of magnetic heads, whereby the time required for the sense current to be caused to flow through one MR reproducing head is greatly shortened. Therefore, the levels of outputs of the MR reproducing heads can be increased without reduction of the reliability and thus the reliability of the magnetic recording drive can be improved.
    Type: Grant
    Filed: August 22, 1996
    Date of Patent: January 11, 2000
    Assignee: Hitachi, Ltd.
    Inventors: Hajime Aoi, Toshiaki Tsuyoshi, Makoto Koizumi, Nobumasa Nishiyama, Yoshibumi Matsuda, Takuji Ogawa, Kazuhisa Shiraishi
  • Patent number: 5740142
    Abstract: A fast data transfer system capable of eliminating the need to extremely increase the necessary transmission frequency band for the high-density recording and fast revolution rate of data recording and reproducing system has a recording and reproduced signal processor including an encoder/decoder, a disk enclosure including a parallel-to-serial converter, a record head, and a serial-to-parallel converter, and a transmission cable, and makes recording parallel data transfer from the encoder/decoder to a recording amplifier by shifting the phases of a plurality of recording signals and reproduced parallel data from the serial-to-parallel converter to the encoder/decoder by shifting the phases of a plurality of reproduced signals. The necessary transmission frequency on the transmission cable can be reduced by this parallel data transfer on the transmission cable. In addition, a record timing correction circuit can be provided on a parallel data transfer path.
    Type: Grant
    Filed: August 5, 1996
    Date of Patent: April 14, 1998
    Assignee: Hitachi, Ltd.
    Inventors: Nobumasa Nishiyama, Hajime Aoi
  • Patent number: 5689494
    Abstract: A fine-fabrication method of solid surfaces relates to a new surface fabrication method allows a solid-device surface to be fabricated at an atomic scale so as to produce an ultra-fine device or a device for recording information at an ultra-high density. A probe is installed with a tip thereof facing to the surface of a specimen to undergo fabrication. A voltage for forming an electric field is applied between the probe and the specimen. The electric field is large enough to field-evaporate atoms constituting the specimen or the probe; the electric field field-evaporates atoms constituting the specimen, removing them from the surface of the specimen; and as another alternative, the electric field field-evaporates atoms constituting the probe, depositing them on the surface of the specimen.
    Type: Grant
    Filed: May 15, 1995
    Date of Patent: November 18, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Masakazu Ichikawa, Shigeyuki Hosoki, Fumihiko Uchida, Shigeo Kato, Yoshihisa Fujisaki, Sumiko Fujisaki, Atsushi Kikugawa, Ryo Imura, Hajime Aoi, Kiyokazu Nakagawa, Eiichi Murakami
  • Patent number: 5671107
    Abstract: A magnetic disc apparatus has a large recording density of 120 megabits per square inch or more, and defines a relationship among a pole thickness (Pt) of thin-film magnetic heads disposed in the magnetic disc apparatus, and a saturation flux density (Bs) of cores of the heads and a recording wavelength (.lambda.) for the thin film magnetic discs have a coercivity of 1800 Oe or more, wherein a levitation space between the head and the disc is 0.15 .mu.m or less.
    Type: Grant
    Filed: March 6, 1995
    Date of Patent: September 23, 1997
    Assignee: Hitachi, Ltd.
    Inventors: Katsuya Mitsuoka, Hiroshi Fukui, Makoto Aihara, Masanori Tanabe, Moriaki Fuyama, Shinji Narishige, Yutaka Sugita, Yoshihiro Shiroishi, Hajime Aoi, Yokuo Saitoh, Kanji Kawakami, Yoshikazu Tsuji, Masaaki Hayashi, Kazuo Nakagoshi
  • Patent number: 5572379
    Abstract: In a magnetic recording drive having a plurality of magnetic heads each employing a magnetoresistive sensor for the purpose of averaging the time required for sense currents to be caused to flow through the respective magnetoresistive sensors to shorten the longest reproducing time and to suppress the degradation of the characteristics due to the electromigration, thereby improving the reliability of the magnetic recording drive, the magnetic recording drive includes circuits for averaging the useful life depending on the currents caused to flow through the respective magnetoresistive sensors among the plurality of magnetic heads, whereby the time required for the sense current to be caused to flow through one MR reproducing head is greatly shortened. Therefore, the levels of outputs of the MR reproducing heads can be increased without reduction of the reliability and thus the reliability of the magnetic recording drive can be improved.
    Type: Grant
    Filed: September 13, 1994
    Date of Patent: November 5, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Hajime Aoi, Toshiaki Tsuyoshi, Makoto Koizumi, Nobumasa Nishiyama, Yoshibumi Matsuda, Takuji Ogawa, Kazuhisa Shiraishi
  • Patent number: 5572699
    Abstract: A file system including an input/output unit for inputting data from and outputting data to an external system; a controller connected to the input/output unit for dividing the data into an optional number of parallel data; a management table for storing the number of divisions of the data; a head group for writing the divided parallel data into a storage medium at the same time; and a unit for reading the data from the storage medium while referring to information stored in management device.
    Type: Grant
    Filed: March 15, 1993
    Date of Patent: November 5, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Yoshihisa Kamo, Hajime Aoi, Hitoshi Kakuta, Yoshito Tsunoda, Hiromichi Fujisawa, Yosuke Seo, Yasuhide Ouchi
  • Patent number: 5568331
    Abstract: A method and device of head positioning in an information recording/reading device in which a magnetic recording medium with data tracks for recording information thereon is provided and a magnetic head is positioned on the data track to record/read out the information, wherein a data signal is recorded in the data recording layer of said recording medium, a servo signal is recorded in the servo signal recording layer located below said data signal recording layer, said data signal is read out using a data magnetic head whereas said servo signal is read out using a servo magnetic head, and the frequency of said servo signal is within the range of the gap-null frequency of said data magnetic head whereas the frequency of said data signal is within the range of the gap-null frequency of said servo magnetic head, and said magnetic head is positioned on the data track on the basis of said servo signal.
    Type: Grant
    Filed: October 25, 1990
    Date of Patent: October 22, 1996
    Assignee: Hitachi, Ltd.
    Inventors: Kyo Akagi, Masaaki Futamoto, Fumio Kugiya, Yoshinori Miyamura, Hisashi Takano, Yoshibumi Matsuda, Mikio Suzuki, Takeshi Nakao, Takayuki Munemoto, Hirotsugu Fukuoka, Makoto Aihara, Tokuho Takagaki, Hajime Aoi, Yosuke Seo
  • Patent number: 5416331
    Abstract: A fine-fabrication method of solid surfaces relates to a new surface fabrication method allows a solid-device surface to be fabricated at an atomic scale so as to produce an ultra-fine device or a device for recording information at an ultra-high density. A probe is installed with a tip thereof facing to the surface of a specimen to undergo fabrication. A voltage for forming an electric field is applied between the probe and the specimen. The electric field is large enough to field-evaporate atoms constituting the specimen or the probe; the electric field field-evaporates atoms constituting the specimen, removing them from the surface of the specimen; and as another alternative, the electric field field-evaporates atoms constituting the probe, depositing them on the surface of the specimen.
    Type: Grant
    Filed: September 11, 1992
    Date of Patent: May 16, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Masakazu Ichikawa, Shigeyuki Hosoki, Fumihiko Uchida, Shigeo Kato, Yoshihisa Fujisaki, Sumiko Fujisaki, Atsushi Kikugawa, Ryo Imura, Hajime Aoi, Kiyokazu Nakagawa, Eiichi Murakami
  • Patent number: 5402428
    Abstract: An array disk subsystem including a command selector for separating a signal from a host into a data item and a command, a data dividing unit for subdividing the data item, an ECC generator for producing an ECC for each of the obtained subdata items, a group of data disks for respectively storing thereon the subdata items and the ECCs, a command interpreting unit for interpreting the command, an I/O counter for counting I/O commands in the command, a backup processor for requesting a backup command based on count information of the I/O counter, and a backup unit responsive to the backup command for sequentially reading the subdata items and the ECCs from the data disks to record therein the subdata items and the ECCs.
    Type: Grant
    Filed: December 19, 1990
    Date of Patent: March 28, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Hitoshi Kakuta, Yoshihisa Kamo, Hajime Aoi