Patents by Inventor Nobuhiro Kuwamura
Nobuhiro Kuwamura 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).
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Patent number: 8098448Abstract: A method for dividing a data area on a disk into a plurality of concentric zones and determining a format for each zone so that data tracks in the zone have the same number of data sectors. The method includes dividing a data area into a plurality of zones with provisional boundaries. The method also includes determining a linear recording density for a selected zone. The method further includes selecting the number of data sectors per data track corresponding to the determined linear recording density from specified values. Moreover, the method includes resetting a boundary of the zone at a new boundary shifted from the provisional boundary according to a selected value.Type: GrantFiled: December 16, 2009Date of Patent: January 17, 2012Assignee: Hitachi Global Storage Technologies, Netherlands B.V.Inventors: Yoshihiko Maeda, Masaomi Ikeda, Nobuhiro Kuwamura, Toshihiko Tsunokawa, Akira Osaki
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Patent number: 8068299Abstract: Embodiments of the present invention help to reduce the occurrence of read hard errors in a hard disk drive (HDD). According to one embodiment, a HDD rewrites data on all data tracks of a block M when the number of write operations to the block consisting of continuous plural data tracks. The HDD further rewrites data on continuous plural data tracks and adjacent to the block. Since the number of write operations is counted every block, a memory area to register the number of write operations can be reduced.Type: GrantFiled: March 26, 2008Date of Patent: November 29, 2011Assignee: Hitachi Global Storage Technologies, Netherlands B.V.Inventors: Toshihiko Tsunokawa, Nobuhiro Kuwamura, Masutaka Harada, Yuhji Yokoe, Takao Matsui
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Publication number: 20110085259Abstract: A method for dividing a data area on a disk into a plurality of concentric zones and determining a format for each zone so that data tracks in the zone have the same number of data sectors. The method includes dividing a data area into a plurality of zones with provisional boundaries. The method also includes determining a linear recording density for a selected zone. The method further includes selecting the number of data sectors per data track corresponding to the determined linear recording density from specified values. Moreover, the method includes resetting a boundary of the zone at a new boundary shifted from the provisional boundary according to a selected value.Type: ApplicationFiled: December 16, 2009Publication date: April 14, 2011Inventors: Yoshihiko MAEDA, Masaomi Ikeda, Nobuhiro Kuwamura, Toshihiko Tsunokawa, Akira Osaki
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Patent number: 7852594Abstract: Embodiments of the present invention help to detect contact between a head and a magnetic disk more accurately in specifying a heater power value for adjusting a clearance between a head element portion and the disk. According to one embodiment, a hard disk controller/multiprocessing unit (HDC/MPU) measures amplitudes of read signals in a user data field DATA. A hard disk drive (HDD) fills a gap between servo data with single data sector. The HDC/MPU measures the amplitudes of read signals in each data sector at different heater power values. It determines the heater power value at which contact occurs from the measured values.Type: GrantFiled: May 28, 2008Date of Patent: December 14, 2010Assignee: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Yoshihiko Maeda, Takao Matsui, Nobuhiro Kuwamura, Kenichi Kuramoto, Akihiro Sera
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Publication number: 20090296260Abstract: Embodiments of the present invention help to detect contact between a head and a magnetic disk more accurately in specifying a heater power value for adjusting a clearance between a head element portion and the disk. According to one embodiment, a hard disk controller/multiprocessing unit (HDC/MPU) measures amplitudes of read signals in a user data field DATA. A hard disk drive (HDD) fills a gap between servo data with single data sector. The HDC/MPU measures the amplitudes of read signals in each data sector at different heater power values. It determines the heater power value at which contact occurs from the measured values.Type: ApplicationFiled: May 28, 2008Publication date: December 3, 2009Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventors: Yoshihiko Maeda, Takao Matsui, Nobuhiro Kuwamura, Kenichi Kuramoto, Akihiro Sera
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Patent number: 7483230Abstract: Embodiments of the present invention provide a write-current control chip capable of effectively preventing adjacent track interference (ATI) that occurs depending on how a magnetic disk drive is used, and to provide a magnetic disk drive using the write-current control chip. In one embodiment, a write-current control chip and a magnetic disk drive using the same are provided. The write-current control chip includes: an acquisition module for acquiring the number of times of write processing in which a magnetic head writes data to a magnetic disk in the magnetic disk drive; a determination module, on the basis of the acquired number of times of write processing, for determining a write-current value used when the magnetic head writes data to the magnetic disk; and an instruction mechanism for instructing the magnetic head to write the data to the magnetic disk by use of the determined write-current value.Type: GrantFiled: March 1, 2006Date of Patent: January 27, 2009Assignee: Hitachi Global Storage Technologies Netherlands B.V.Inventor: Nobuhiro Kuwamura
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Publication number: 20080239901Abstract: Embodiments of the present invention help to reduce the occurrence of read hard errors in a hard disk drive (HDD). According to one embodiment, a HDD rewrites data on all data tracks of a block M when the number of write operations to the block consisting of continuous plural data tracks. The HDD further rewrites data on continuous plural data tracks and adjacent to the block. Since the number of write operations is counted every block, a memory area to register the number of write operations can be reduced.Type: ApplicationFiled: March 26, 2008Publication date: October 2, 2008Inventors: Toshihiko Tsunokawa, Nobuhiro Kuwamura, Masutaka Harada, Yuhji Yokoe, Takao Matsui
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Patent number: 7177979Abstract: Where a leakage magnetic field deletes data on adjacent tracks gradually, such deletion is compensated so as to prevent data errors from occurring. A magnetic disk device includes one or more magnetic disks, one or more magnetic heads, and a write and read circuit for writing or reading data, and writes or reads the data on tracks on the magnetic disks. The number of writes of the data on a given track is acquired. If the number of writes reaches a predetermined number, the data on the tracks adjacent to a given track is read out once and, then, the data is rewritten on the adjacent tracks. Further, when the data is written on the tracks, the data is written on alternate physical tracks and every other track is skipped, and after the data is written on half of all tracks, the data is written on the skipped tracks.Type: GrantFiled: September 29, 2003Date of Patent: February 13, 2007Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventor: Nobuhiro Kuwamura
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Publication number: 20060198041Abstract: Embodiments of the present invention provide a write-current control chip capable of effectively preventing adjacent track interference (ATI) that occurs depending on how a magnetic disk drive is used, and to provide a magnetic disk drive using the write-current control chip. In one embodiment, a write-current control chip and a magnetic disk drive using the same are provided. The write-current control chip includes: an acquisition module for acquiring the number of times of write processing in which a magnetic head writes data to a magnetic disk in the magnetic disk drive; a determination module, on the basis of the acquired number of times of write processing, for determining a write-current value used when the magnetic head writes data to the magnetic disk; and an instruction mechanism for instructing the magnetic head to write the data to the magnetic disk by use of the determined write-current value.Type: ApplicationFiled: March 1, 2006Publication date: September 7, 2006Applicant: Hitachi Global Storage Technologies Netherlands B.V.Inventor: Nobuhiro Kuwamura
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Patent number: 6927931Abstract: A magnetic head is disposed opposite to a magnetic disk having a first recording area capable of facilitating writing information to the magnetic disk when the surrounding temperature is low, and a second recording area capable of surely holding information written to the magnetic disk when the surrounding temperature is high. Information is written to the first recording area when the surrounding temperature is low and is transferred later to the second recording area.Type: GrantFiled: August 27, 2003Date of Patent: August 9, 2005Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Hiroshi Harata, Atsuo Suga, Yuji Suzuki, Nobuhiro Kuwamura
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Patent number: 6920599Abstract: Positions in which errors have occurred are found more accurately and erasure correction is performed more effectively than in cases where TA flags or error flags issued by the R/W channel are utilized as information indicating the positions in which errors have occurred, [this being accomplished] by reading the same sector on the magnetic disk a plurality of times, storing the plurality of NRZ data thus obtained, comparing these NRZ data in byte units, judging that an error has occurred in byte positions where the NRZ data reproduced in each read operation differs, and utilizing these positions as erasure pointers for erasure correction.Type: GrantFiled: February 7, 2002Date of Patent: July 19, 2005Assignee: Hitachi Global Storage Technologies Japan, Ltd.Inventor: Nobuhiro Kuwamura
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Publication number: 20040223250Abstract: A magnetic head is disposed opposite to a magnetic disk having a first recording area capable of facilitating writing information to the magnetic disk when the surrounding temperature is low, and a second recording area capable of surely holding information written to the magnetic disk when the surrounding temperature is high. Information is written to the first recording area when the surrounding temperature is low and is transferred later to the second recording area.Type: ApplicationFiled: August 27, 2003Publication date: November 11, 2004Applicant: Hitachi Global Storage Technologies Japan, Ltd.Inventors: Hiroshi Harata, Atsuo Suga, Yuji Suzuki, Nobuhiro Kuwamura
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Publication number: 20040193798Abstract: Where a leakage magnetic field deletes data on adjacent tracks gradually, such deletion is compensated so as to prevent data errors from occurring. A magnetic disk device includes one or more magnetic disks, one or more magnetic heads, and a write and read circuit for writing or reading data, and writes or reads the data on tracks on the magnetic disks. The number of writes of the data on a given track is acquired. If the number of writes reaches a predetermined number, the data on the tracks adjacent to a given track is read out once and, then, the data is rewritten on the adjacent tracks. Further, when the data is written on the tracks, the data is written on alternate physical tracks and every other track is skipped, and after the data is written on half of all tracks, the data is written on the skipped tracks.Type: ApplicationFiled: September 29, 2003Publication date: September 30, 2004Applicant: Hitachi Global Storage Technologies Japan, Ltd.Inventor: Nobuhiro Kuwamura
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Publication number: 20030066017Abstract: Positions in which errors have occurred are found more accurately and erasure correction is performed more effectively than in cases where TA flags or error flags issued by the R/W channel are utilized as information indicating the positions in which errors have occurred, [this being accomplished] by reading the same sector on the magnetic disk a plurality of times, storing the plurality of NRZ data thus obtained, comparing these NRZ data in byte units, judging that an error has occurred in byte positions where the NRZ data reproduced in each read operation differs, and utilizing these positions as erasure pointers for erasure correction.Type: ApplicationFiled: February 7, 2002Publication date: April 3, 2003Inventor: Nobuhiro Kuwamura