Patents by Inventor Tatsuya Kawashimo

Tatsuya Kawashimo 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: 7417818
    Abstract: A magnetic recording device capable of reducing the size of a writing circuit and the power consumption by readily adjusting the overshoot of the write current pulses is provided. Two or more transmission lines having different characteristic impedances are provided between an output driver having an impedance Zs and a magnetic head, the transmission lines are formed so that the characteristic impedances Z1, Zn?1, and Zn (n?2) thereof on the output driver side are higher than those on the magnetic recording head side (Z1>Zn?1>Zn), and the impedance Zs of the output driver is equal to or higher than the characteristic impedance Z1 of the transmission line.
    Type: Grant
    Filed: January 31, 2006
    Date of Patent: August 26, 2008
    Assignee: Hitachi, Ltd.
    Inventors: Fumio Yuuki, Hiroki Yamashita, Masayoshi Yagyu, Tatsuya Kawashimo
  • Patent number: 7373114
    Abstract: This invention provides a signal transmission circuit, a signal output circuit, and a termination method of a signal transmission circuit capable of preventing the re-reflection of the signal at a transmitting node of a transmission path even when an impedance of a signal output circuit does not match a characteristic impedance of a transmission path. On a signal transmission circuit composed of a transmission path, a signal output circuit connected to a transmitting node of the transmission path, and a signal receiver circuit connected to a receiving node of the signal transmission path, in order to prevent the re-reflection of an output signal of a signal output unit at the transmitting node via the receiving node, a correction current generator unit is provided for outputting correction current with a predetermined current amount and at a predetermined timing set in a current amount/timing control section, to the transmitting node.
    Type: Grant
    Filed: January 7, 2005
    Date of Patent: May 13, 2008
    Assignee: Hitachi, Ltd.
    Inventors: Masayoshi Yagyu, Hiroki Yamashita, Fumio Yuuki, Tatsuya Kawashimo
  • Patent number: 7319575
    Abstract: This invention provides a semiconductor device in which an ESD protection circuit and a termination circuit can be realized with a small die area. A PMOS transistor having an ESD protection function is placed between a signal node on a line from an signal terminal to an input buffer and a supply voltage node. Furthermore, a voltage generator circuit is placed to supply a reference voltage to the gate of the PMOS transistor. By the reference voltage controlled by the voltage generator circuit, a source drain resistance of the PMOS transistor is set. Thereby, the PMOS transistor can be made to function as a terminating resistor whose resistance can be set adaptively to a characteristic impedance of a transmission line, for example, connected to the signal terminal in addition to the ESD protection function.
    Type: Grant
    Filed: November 29, 2005
    Date of Patent: January 15, 2008
    Assignee: Hitachi, Ltd.
    Inventors: Tatsuya Kawashimo, Hiroki Yamashita, Masayoshi Yagyu
  • Patent number: 7127717
    Abstract: A hierarchical server system efficiently balances the processing load thereon and for shortening the processing time therein is provided, such as a web server system. A system controller, a load balancing device, and a shared memory are provided in a multi-layer server system made of a plurality of servers. When processing implemented with a first layer server is temporarily stopped in order to acquire information needed for processing from a second layer server, process information needed to resume the processing is recorded in the shared memory. When the necessary information is sent back to the first layer server, the system controller inquires about work statuses of all first layer servers to select another first layer server to resume the processing based upon the inquiry results. The then selected first layer server then resumes the processing using the information that was sent back and the process information in the shared memory.
    Type: Grant
    Filed: August 13, 2002
    Date of Patent: October 24, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Tatsuya Kawashimo, Yoshio Miki, Hiroaki Fujii, Akihiro Takamura
  • Publication number: 20060203372
    Abstract: A magnetic recording device capable of reducing the size of a writing circuit and the power consumption by readily adjusting the overshoot of the write current pulses is provided. Two or more transmission lines having different characteristic impedances are provided between an output driver having an impedance Zs and a magnetic head, the transmission lines are formed so that the characteristic impedances Z1, Zn?1, and Zn (n?2) thereof on the output driver side are higher than those on the magnetic recording head side (Z1>Zn?1>Zn), and the impedance Zs of the output driver is equal to or higher than the characteristic impedance Z1 of the transmission line.
    Type: Application
    Filed: January 31, 2006
    Publication date: September 14, 2006
    Inventors: Fumio Yuuki, Hiroki Yamashita, Masayoshi Yagyu, Tatsuya Kawashimo
  • Publication number: 20060158802
    Abstract: This invention provides a semiconductor device in which an ESD protection circuit and a termination circuit can be realized with a small die area. A PMOS transistor having an ESD protection function is placed between a signal node on a line from an signal terminal to an input buffer and a supply voltage node. Furthermore, a voltage generator circuit is placed to supply a reference voltage to the gate of the PMOS transistor. By the reference voltage controlled by the voltage generator circuit, a source-drain resistance of the PMOS transistor is set. Thereby, the PMOS transistor can be made to function as a terminating resistor whose resistance can be set adaptively to a characteristic impedance of a transmission line, for example, connected to the signal terminal in addition to the ESD protection function.
    Type: Application
    Filed: November 29, 2005
    Publication date: July 20, 2006
    Inventors: Tatsuya Kawashimo, Hiroki Yamashita, Masayoshi Yagyu
  • Patent number: 7046468
    Abstract: The present invention provides a semiconductor integrated circuit capable of reducing a circuit area and a magnetic storage device using the same. The circuit in the present invention is provided with a single-stage output transistor for supplying write current to a magnetic head, a current source for outputting reference current of the write current, a diode-connected NMOS transistor for converting the current to gate voltage and having a certain device size ratio to the output transistor, a regulator circuit for transmitting gate voltage of the NMOS transistor and reducing output impedance, and a CMOS circuit for setting power supply voltage to an output of the regulator circuit and controlling the gate voltage of the output transistor. Then, this circuit is applied as a write circuit in a magnetic storage device.
    Type: Grant
    Filed: January 7, 2005
    Date of Patent: May 16, 2006
    Assignee: Hitachi, Ltd.
    Inventors: Hiroki Yamashita, Masayoshi Yagyu, Fumio Yuuki, Tatsuya Kawashimo
  • Publication number: 20050207228
    Abstract: The present invention provides a semiconductor integrated circuit capable of reducing a circuit area and a magnetic storage device using the same. The circuit in the present invention is provided with a single-stage output transistor for supplying write current to a magnetic head, a current source for outputting reference current of the write current, a diode-connected NMOS transistor for converting the current to gate voltage and having a certain device size ratio to the output transistor, a regulator circuit for transmitting gate voltage of the NMOS transistor and reducing output impedance, and a CMOS circuit for setting power supply voltage to an output of the regulator circuit and controlling the gate voltage of the output transistor. Then, this circuit is applied as a write circuit in a magnetic storage device.
    Type: Application
    Filed: January 7, 2005
    Publication date: September 22, 2005
    Inventors: Hiroki Yamashita, Masayoshi Yagyu, Fumio Yuuki, Tatsuya Kawashimo
  • Publication number: 20050208902
    Abstract: This invention provides a signal transmission circuit, a signal output circuit, and a termination method of a signal transmission circuit capable of preventing the re-reflection of the signal at a transmitting node of a transmission path even when an impedance of a signal output circuit does not match a characteristic impedance of a transmission path. On a signal transmission circuit composed of a transmission path, a signal output circuit connected to a transmitting node of the transmission path, and a signal receiver circuit connected to a receiving node of the signal transmission path, in order to prevent the re-reflection of an output signal of a signal output unit at the transmitting node via the receiving node, a correction current generator unit is provided for outputting correction current with a predetermined current amount and at a predetermined timing set in a current amount/timing control section, to the transmitting node.
    Type: Application
    Filed: January 7, 2005
    Publication date: September 22, 2005
    Inventors: Masayoshi Yagyu, Hiroki Yamashita, Fumio Yuuki, Tatsuya Kawashimo
  • Patent number: 6832298
    Abstract: A main logical unit and a standby logical unit are defined by a process controller in a shared main memory multiprocessor, and an information storage space accessible from both logical units is provided. The main logical unit stores address information onto that information storage space by indicating a memory area it controls as the main memory area. When failover or cloning becomes necessary, the standby logical unit searches the information on the applicable address. Then from the applicable information, it also searches information on the main memory area controlled by the main logical unit to establish in itself and forms a processing environment and state identical to the main logical unit such that the standby logical unit takes over all or a portion of the processing of the main logical unit. This enables the construction of a server system of high operability to overcome failures and poor response times by failover and cloning, etc.
    Type: Grant
    Filed: August 28, 2002
    Date of Patent: December 14, 2004
    Assignee: Hitachi, Ltd.
    Inventors: Hiroaki Fujii, Yoshio Miki, Tatsuya Kawashimo, Akihiro Takamura
  • Publication number: 20030154288
    Abstract: In a server-client system, data transmitted by an application of a client computer is stored in a client computer. Whether an application of a server computer terminates normally is reported to the client computer. When the application does not terminate normally, the stored data is retransmitted to another server computer.
    Type: Application
    Filed: July 18, 2002
    Publication date: August 14, 2003
    Applicant: Hitachi, Ltd.
    Inventors: Akihiro Takamura, Yoshio Miki, Hiroaki Fujii, Tatsuya Kawashimo
  • Publication number: 20030120724
    Abstract: A hierarchical server system for efficiently balancing the processing load thereon and for shortening the processing time therein is provided, such as a web server system. A system controller and a shared memory means are provided in a multi-layer server system made of a plurality of servers. When processing implemented with a first layer server is temporarily stopped in order to acquire information needed for processing form a second layer server, process information needed to resume the processing is recorded in the shared memory means. When the necessary information is sent back to the first layer server, the system controller inquires about work status of all first layer servers to select another first layer server to resume the processing based upon the inquiry results. The then selected first layer server then resumes the processing using the information that was sent back and the process information in the shared memory means.
    Type: Application
    Filed: August 13, 2002
    Publication date: June 26, 2003
    Applicant: Hitachi, Ltd.
    Inventors: Tatsuya Kawashimo, Yoshio Miki, Hiroaki Fujii, Akihiro Takamura
  • Publication number: 20030079093
    Abstract: A main logical unit and a standby logical unit are defined by a process controller in a shared main memory multiprocessor, and an information storage space accessible from both logical units is provided. The main logical unit stores address information onto that information storage space by indicating a memory area it controls as the main memory area. When failover or cloning becomes necessary, the standby logical unit searches the information on the applicable address. Then from the applicable information, it also searches information on the main memory area controlled by the main logical unit to establish in itself and forms a processing environment and state identical to the main logical unit such that the standby logical unit takes over all or a portion of the processing of the main logical unit. This enables the construction of a server system of high operability to overcome failures and poor response times by failover and cloning, etc.
    Type: Application
    Filed: August 28, 2002
    Publication date: April 24, 2003
    Inventors: Hiroaki Fujii, Yoshio Miki, Tatsuya Kawashimo, Akihiro Takamura
  • Patent number: 5881078
    Abstract: Soft errors generated at an active time are reduced by adding a small-scale circuit to a high performance LSI, such as a processor without reducing the performance of the circuit. The processor has individual logic circuits each having a plurality of stages of logic gates for outputting true signals and complement signals for the individual logic gates. A latch circuit latches the true and complement signals of the logic circuits separately and a compare circuit detects for an error by comparing the true and complement output signals of the logic circuits to determine if they are at the same logical signal level or not, just upstream of the latch in which the individual true and complement output signals of the final logic circuit stages are individually latched. When the compare circuit detects an error because the true and complement output signals are at the same logical signal level, a recovery process is executed.
    Type: Grant
    Filed: December 12, 1997
    Date of Patent: March 9, 1999
    Assignee: Hitachi, Ltd.
    Inventors: Makoto Hanawa, Yoshio Miki, Tatsuya Kawashimo