Patents by Inventor Kenichi Nakata

Kenichi Nakata 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).

  • Publication number: 20050052800
    Abstract: When an output voltage output from a buffer approaches a ground voltage, a MOS transistor turns off, so that clamp for a gate of the MOS transistor is released.
    Type: Application
    Filed: September 9, 2004
    Publication date: March 10, 2005
    Inventors: Mikiya Doi, Kenichi Nakata
  • Publication number: 20050024033
    Abstract: The present invention provides a DC/DC converter that can include a capacitor constituting a soft start circuit in a semiconductor integrated device. This DC/DC converter is comprised of a switching element for supplying power from a power supply (Vcc) to a load side output terminal (OUT) by switching, an error amplifier for amplifying the voltage from the load side output terminal (OUT), a differentiation circuit for differentiating the voltage from the load side output terminal (OUT) and adjusting the output current according to the value thereof, a soft start circuit comprising a constant current source and a capacitor, both of which are connected to the output terminal of the differentiation circuit, and a comparator for comparing the triangular wave voltage from a triangular wave generator (TRI) with the voltage from the soft start circuit or the output voltage of the error amplifier, and controlling the switching of the switching element according to the comparison output thereof.
    Type: Application
    Filed: July 23, 2004
    Publication date: February 3, 2005
    Inventor: Kenichi Nakata
  • Publication number: 20050001671
    Abstract: A constant voltage generator is comprised of a band gap reference circuit, a current supply circuit, a starting circuit and a voltage-current conversion circuit, and the starting circuit is further comprised of a first and second load elements, a first transistor which is connected to the first load element, a second transistor of which current capability is larger than the first transistor and which shares the voltage of the base with the first transistor and is connected to the second load element, a first resistor which is connected to the first transistor, and a second resistor which is connected to the second transistor, and the output of the voltage-current conversion circuit is input to the connection point between the second transistor and the second resistor, and the current at the connection point between the second load element and the second transistor controls the current supply circuit.
    Type: Application
    Filed: June 18, 2004
    Publication date: January 6, 2005
    Inventor: Kenichi Nakata
  • Publication number: 20040257057
    Abstract: A DC/DC converter is supplied such that the desired output setting voltage can be obtained as the load-side output, even when the difference between the power supply voltage and the output setting voltage of the load-side output is large. This DC/DC converter comprises a switching device, a voltage divider, an error amplifier, an oscillator which outputs a oscillation clock, a slope circuit which receives the oscillation clock and outputs a sawtooth waveform voltage having a slope which begins at the leading edge of the oscillation clock, a comparator which compares the sawtooth waveform voltage and the output voltage of the error amplifier, and a logic circuit which is set by the trailing edge of the oscillation clock, and is reset by the output of the comparator.
    Type: Application
    Filed: June 18, 2004
    Publication date: December 23, 2004
    Applicant: ROHM CO., LTD.
    Inventors: Kenichi Nakata, Mikiya Doi
  • Patent number: 6821618
    Abstract: A magnetic recording medium exhibiting a high coercive force and excellent squareness having a substrate, an underlayer formed on the substrate, and a spinel-type iron oxide thin film with maghemite as a main component formed on the underlayer. The spinel-type iron oxide thin film has a thickness (t) of 5 to 50 nm, is constituted by grains having an average grain size (D) of 5 to 30 nm, standard deviation of sizes of grain of not more than 4 nm and a ratio (D/t) of the average grain size (D) to the thickness (t) of less than 1.0, exhibits a coercive force of not less than 159 kA/m (2,000 Oe) and a coercive squareness ratio S* of not less than 0.5:1 in a longitudinal recording medium or a squareness ratio not less than 0.75:1 in a perpendicular recording medium.
    Type: Grant
    Filed: July 1, 2002
    Date of Patent: November 23, 2004
    Assignee: Toda Kogyo Corporation
    Inventors: Jun Koujima, Teruaki Santoki, Kenichi Nakata, Takanori Doi, Masaaki Maekawa, Kousaku Tamari
  • Patent number: 6753077
    Abstract: A magnetic recording medium including a substrate and formed on the substrate a maghemite thin film having a surface roughness represented by a center line mean roughness Ra of 0.1 to 1.0 nm, and a coercive force squareness S* value of not less than 0.50. This magnetic recording medium exhibits excellent magnetic properties, especially, coercive force squareness S* value and a more enhanced surface smoothness.
    Type: Grant
    Filed: December 22, 2000
    Date of Patent: June 22, 2004
    Assignee: Toda Kogyo Corporation
    Inventors: Kenichi Nakata, Kousaku Tamari, Jun Koujima, Teruaki Santoki
  • Publication number: 20040095105
    Abstract: A power supply device relating to the invention comprises a switching element connected between two different potentials, an output smoothing section for smoothing a voltage outputted from a terminal of the switching element and produce an output voltage provided for a load, a driver section for driving and controlling the switching element, and an output current sensing section for monitoring current flowing through the load, the output current sensing section provided in a stage after the output smoothing section. The power supply device is configured in such a way that, when a desired output voltage is produced from an input voltage, the switching element is driven and controlled by the driver section by incorporating a monitored result obtained by the output current sensing section. According to this configuration, it is possible to produce a stable output voltage even if there are abrupt changes of load.
    Type: Application
    Filed: November 14, 2003
    Publication date: May 20, 2004
    Applicant: ROHM CO., LTD.
    Inventor: Kenichi Nakata
  • Publication number: 20040090409
    Abstract: A gamma correction voltage generation device relating to the invention has a plurality of sets, each comprising a data holding section for holding digital data inputted thereto, a digital-to-analog converter for converting the digital data held in the data holding section to an analog voltage, and a buffer for amplifying a capacity of current of the analog voltage and outputting the analog voltage, wherein the analog voltages are outputted from the buffers as gamma correction voltages. By this configuration, it becomes possible to perform a process of adjustments on the gamma correction voltages easily and efficiently.
    Type: Application
    Filed: November 7, 2003
    Publication date: May 13, 2004
    Applicant: Rohm Co., Ltd.
    Inventors: Kenichi Nakata, Mikiya Doi, Koichi Inoue
  • Publication number: 20030210022
    Abstract: The power supply unit is provided with a power supply circuit adapted to generate an output voltage in accord with an instruction voltage, an output condenser Co connected to the output end of the power supply circuit, and an auxiliary output voltage setting circuit adapted to compare the instruction voltage and the output voltage and to cause the output condenser to discharge its electric charge when the instruction voltage becomes lower than the output voltage. Because of the auxiliary output voltage setting circuit, the power supply circuit quickly generates an output voltage in accord with the instruction voltage if the instruction voltage is lowered.
    Type: Application
    Filed: April 25, 2003
    Publication date: November 13, 2003
    Applicant: ROHM CO., LTD.
    Inventors: Ko Takemura, Kiyotaka Umemoto, Kenichi Nakata
  • Publication number: 20030008176
    Abstract: A magnetic recording medium, comprising: a substrate; an underlayer formed on the substrate; and a spinel-type iron oxide thin film comprising maghemite as a main component formed on the underlayer,
    Type: Application
    Filed: July 1, 2002
    Publication date: January 9, 2003
    Inventors: Jun Koujima, Teruaki Santoki, Kenichi Nakata, Takanori Doi, Masaaki Maekawa, Kousaku Tamari
  • Publication number: 20020094458
    Abstract: A magnetic recording medium, comprising: a substrate; and a maghemite thin film formed on the substrate, having a surface roughness represented by a center line mean roughness Ra of 0.1 to 1.0 nm, and a coercive force squareness S* value of not less than 0.50.
    Type: Application
    Filed: December 22, 2000
    Publication date: July 18, 2002
    Inventors: Kenichi Nakata, Kousaku Tamari, Jun Koujima, Teruaki Santoki
  • Patent number: 6268024
    Abstract: A magnetic recording medium is prepared by forming on a plastic substrate, a nickel oxide underlayer having a plane (200) which is predominantly oriented in parallel with the surface of the plastic substrate, then forming on the nickel oxide underlayer at a substrate temperature of less 240° C., a cobalt-containing magnetite thin film having a plane (400) which is predominantly oriented in parallel with the surface of the plastic substrate, and finally oxidizing the cobalt-containing magnetite thin film in a plasma-activated oxygen atmosphere containing a rare gas at a substrate temperature of less than 240° C. while incorporating the rare gas into oxygen. This results in a cobalt-containing maghemite thin film as a perpendicular magnetic film having a spacing of a plane (400) of not more than 2.082 Å. The magnetic recording medium so produced is useful for high-density recording using a plastic substrate.
    Type: Grant
    Filed: March 25, 1999
    Date of Patent: July 31, 2001
    Assignee: Toda Kogyo Corporation
    Inventors: Takanori Doi, Kousaku Tamari, Yasuo Kakihara, Kenichi Nakata, Mitsuru Matsuura, Setsuo Yamamoto
  • Patent number: 6221519
    Abstract: A magnetic recording medium comprising: a plastic substrate; a nickel oxide underlayer formed on said substrate; and a cobalt-containing maghemite thin film formed on said nickel oxide underlayer, containing cobalt at a molar ratio of cobalt to iron of 0.01:1 to 0.1:1, and having either a spacing of a plane (311) of not more than 2.510 Å, a spacing of a plane (222) of not more than 2.415 Å or a spacing of a plane (220) of not more than 2.950 Å, a ratio value of an X-ray diffraction pattern peak intensity of either of the planes (311), (222) and (220) of said cobalt-containing maghemite thin film to an X-ray diffraction pattern peak intensity of the plane (400) thereof being more than 0.5. Such magnetic recording medium suitably applicable to existent magnetic recording systems using a ring-type magnetic head and capable of using a plastic substrate for providing a magnetic recording medium for high-density recording.
    Type: Grant
    Filed: March 19, 1999
    Date of Patent: April 24, 2001
    Assignee: Toda Kogyo Corporation
    Inventors: Takanori Doi, Kousaku Tamari, Yasuo Kakihara, Kenichi Nakata, Mitsuru Matsuura, Setsuo Yamamoto
  • Patent number: 6187462
    Abstract: A magnetic recording medium of the present invention comprises: a plastic substrate; and a cobalt-containing maghemite thin film formed on said substrate, containing cobalt at a molar ratio of cobalt to iron of not more than 0.06:1, and having either a spacing of a plane (311) of not more than 2.510 Å, a spacing of a plane (222) of not more than 2.415 Å or a spacing of a plane (220) of not more than 2.950 Å; and has a coercive force of not less than 2,000 Oe. Such magnetic recording medium suitably applicable to existent magnetic recording systems using a ring-type magnetic head and capable of using a plastic substrate for providing a magnetic recording medium for high-density recording.
    Type: Grant
    Filed: March 19, 1999
    Date of Patent: February 13, 2001
    Assignee: Toda Kogyo Corporation
    Inventors: Takanori Doi, Kousaku Tamari, Yasuo Kakihara, Kenichi Nakata, Mitsuru Matsuura, Setsuo Yamamoto
  • Patent number: 6165608
    Abstract: A magnetic recording medium of the present invention comprises:a substrate; anda cobalt-containing maghemite thin film formed on said substrate, containing cobalt at a molar ratio of cobalt to iron of not more than 0.06:1, having either a spacing of a (311) plane of not more than 2.510 .ANG., a spacing of a (222) plane of not more than 2.415 .ANG. or a spacing of a (220) plane of not more than 2.950 .ANG., and having a coercive force of not less than 1,800 Oe.Such a magnetic recording medium has as high a coercive force as possible, specifically not less than 1,800 Oe, and exhibits an excellent stability independent to change in passage of time and a large output in a high recording frequency region.
    Type: Grant
    Filed: September 29, 1998
    Date of Patent: December 26, 2000
    Assignee: Toda Kogyo Corporation
    Inventors: Kousaku Tamari, Takanori Doi, Yasuo Kakihara, Kenichi Nakata
  • Patent number: 6159594
    Abstract: A magnetic recording medium of the present invention comprises:a substrate;a nickel oxide underlayer formed on said substrate; anda cobalt-containing maghemite thin film formed on said nickel oxide underlayer, having either a spacing of a (311) plane of not more than 2.510 .ANG., a spacing of a (222) plane of not more than 2.415 .ANG. or a spacing of a (220) plane of not more than 2.950 .ANG., and having the ratio of either of X-ray diffraction spectrum peak intensities of the (311), (222) or (220) planes of said cobalt-containing maghemite thin film to an X-ray diffraction spectrum peak intensity of the (400) plane of more than 0.5:1.Such a magnetic recording medium has a higher coercive force, a higher saturation magnetization, less amount of noise generated, a large output in a high recording frequency region and less distortion of a reproduced waveform, and is suitable for use in current magnetic recording systems in which a ring-type magnetic write head is used.
    Type: Grant
    Filed: September 29, 1998
    Date of Patent: December 12, 2000
    Assignee: Toda Kogyo Corporation
    Inventors: Kousaku Tamari, Takanori Doi, Yasuo Kakihara, Kenichi Nakata
  • Patent number: 5231339
    Abstract: In a slip frequency control system hitherto widely employed as a control system for an induction motor type electric rolling stock (in which a slip frequency is determined from a current deviation, an inverter frequency is calculated from the slip frequency and a motor rotation frequency, and the inverter frequency is multiplied by a predetermined correction factor to determine a modulation rate, thereby operating an inverter), a motor output torque decreases in a low speed region. It is difficult to make the correction for this decrease of torque by detecting the torque. In the present invention made considering that a torque curve and sin .phi. (.phi.: the internal impedance angle of a motor) obtained from the result of simulation resemble each other, the decrease of sin .phi. is regarded as being the decrease of torque and a voltage to frequency ratio is corrected so as to compensate for the decrease of sin .phi..
    Type: Grant
    Filed: March 18, 1991
    Date of Patent: July 27, 1993
    Assignees: Hitachi, Ltd., Hitachi Techno Engineering Co., Ltd.
    Inventors: Yasuharu Kishimoto, Sadao Asaba, Kenichi Nakata, Shigeo Kawatsu