Patents by Inventor Seiya Kitagawa

Seiya Kitagawa 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: 6414403
    Abstract: A power unit having a built-in battery to supply voltage from the battery over a long period of time by utilizing fully the capabilities of the built-in battery. The power unit supplies electric power to a load even when a battery with a higher battery voltage than the external power source voltage is used by charging the battery from an external power source even when the external power source voltage is lower than the battery voltage. By charging the battery when electric power is supplied to a load from an external power source, the power unit supplies electric power to the load from the battery when the supply of electricity from an external power source is cut off. The power unit includes a having converter to boost output voltage from the battery and to supply the voltage to the load when the battery is discharged and the external power source voltage is higher than the battery voltage.
    Type: Grant
    Filed: September 23, 1998
    Date of Patent: July 2, 2002
    Assignee: Fujitsu Limited
    Inventors: Seiya Kitagawa, Mitsuo Saeki, Hidekiyo Ozawa
  • Publication number: 20020057073
    Abstract: The present invention provides a battery charging/discharging method for effectively using the battery energy of a power supply apparatus with a plurality of chargeable batteries. The power supply apparatus in which batteries are connected in parallel to the node of an external power source and a load comprises a charge/discharge monitor unit for judging whether the external power source is in a state where a load is driven and sufficient voltage to charge the batteries is outputted or in a state where sufficient voltage is not outputted and a discharge current should be supplied from the batteries to the load, switches inserted in series with each of the batteries, and an on/off control unit for controlling the on/off operation of the switches according to the output of the charge/discharge monitor unit and the charging/discharging state of each battery.
    Type: Application
    Filed: January 11, 2002
    Publication date: May 16, 2002
    Inventor: Seiya Kitagawa
  • Publication number: 20010020802
    Abstract: A power unit having a built-in battery to supply voltage from the battery over a long period of time by utilizing fully the capabilities of the built-in battery. The power unit supplies electric power to a load even when a battery with a higher battery voltage than the external power source voltage is used by charging the battery from an external power source even when the external power source voltage is lower than the battery voltage. By charging the battery when electric power is supplied to a load from an external power source, the power unit supplies electric power to the load from the battery when the supply of electricity from an external power source is cut off. The power unit includes a having converter to boost output voltage from the battery and to supply the voltage to the load when the battery is discharged and the external power source voltage is higher than the battery voltage.
    Type: Application
    Filed: September 23, 1998
    Publication date: September 13, 2001
    Inventors: SEIYA KITAGAWA, MITSUO SAEKI, HIDEKIYO OZAWA
  • Publication number: 20010007417
    Abstract: The present invention provides a battery charging/discharging method for effectively using the battery energy of a power supply apparatus with a plurality of chargeable batteries. The power supply apparatus in which batteries are connected in parallel to the node of an external power source and a load comprises a charge/discharge monitor unit for judging whether the external power source is in a state where a load is driven and sufficient voltage to charge the batteries is outputted or in a state where sufficient voltage is not outputted and a discharge current should be supplied from the batteries to the load, switches inserted in series with each of the batteries, and an on/off control unit for controlling the on/off operation of the switches according to the output of the charge/discharge monitor unit and the charging/discharging state of each battery.
    Type: Application
    Filed: January 18, 2001
    Publication date: July 12, 2001
    Inventor: Seiya Kitagawa
  • Patent number: 6204633
    Abstract: The present invention provides a battery charging/discharging method for effectively using the battery energy of a power supply apparatus with a plurality of chargeable batteries. The power supply apparatus in which batteries are connected in parallel to the node of an external power source and a load comprises a charge/discharge monitor unit for judging whether the external power source is in a state where a load is driven and sufficient voltage to charge the batteries is outputted or in a state where sufficient voltage is not outputted and a discharge current should be supplied from the batteries to the load, switches inserted in series with each of the batteries, and an on/off control unit for controlling the on/off operation of the switches according to the output of the charge/discharge monitor unit and the charging/discharging state of each battery.
    Type: Grant
    Filed: August 24, 1998
    Date of Patent: March 20, 2001
    Assignee: Fujitsu Limited
    Inventor: Seiya Kitagawa
  • Patent number: 6194875
    Abstract: A DC—DC converter generates a system output current and a battery charging current. The converter has an output transistor connected between an AC adapter, which provides a supply current, and a terminal at which the battery charging current is provided. A control circuit generates a duty control signal used to activate and deactivate the output transistor in order to adjust the battery charging current. The control circuit includes a voltage detection circuit that compares a DC power supply voltage of the AC adapter with a first reference voltage and generates a differential voltage signal from the comparison result. A PWM comparison circuit is connected to the voltage detection circuit and compares the differential voltage signal with a triangular wave signal to generate the duty control signal which has a duty ratio corresponding to the comparison result.
    Type: Grant
    Filed: October 7, 1999
    Date of Patent: February 27, 2001
    Assignee: Fujitsu Limited
    Inventors: Kyuichi Takimoto, Toshiyuki Matsuyama, Hidekiyo Ozawa, Seiya Kitagawa
  • Patent number: 6169392
    Abstract: A DC—DC converter circuit for performing DC—DC conversion by switching an input voltage on and off achieves high conversion efficiency while, at the same time, making it possible to supply low voltages. The DC—DC converter circuit includes: a level shift circuit which generates a voltage that is lower than the input voltage by a predetermined voltage; a power supply generating circuit which generates a floating power supply having a magnitude equal to the difference between the input voltage and the output voltage of the level shift circuit; a capacitor which is charged up by the floating power supply generated by the power supply generating circuit; and a driver circuit which supplies the charged voltage of the capacitor as a driving voltage to the main switching device in accordance with the operation control signal.
    Type: Grant
    Filed: December 14, 1999
    Date of Patent: January 2, 2001
    Assignee: Fujitsu Limited
    Inventor: Seiya Kitagawa
  • Patent number: 6147477
    Abstract: A direct-current to direct-current conversion (DC/DC) apparatus includes a control circuit having an error amplifier for voltage control and controlling a direct-current to direct-current conversion based on a pulse width modulation control using an output of the error amplifier. The error amplifier inputs a voltage signal corresponding to an output voltage of a DC/DC result and a plurality of reference voltage signals. The DC/DC apparatus also includes a soft start capacitor to provide one of the plurality of reference voltage signals. The error amplifier amplifies a difference between the voltage signal corresponding to the output voltage of a DC/DC result and a voltage signal of a lower potential among the plurality of reference voltage signals and, based on the amplified output, carries out the pulse width modulation control.
    Type: Grant
    Filed: June 27, 1997
    Date of Patent: November 14, 2000
    Assignee: Fujitsu Limited
    Inventors: Mitsuo Saeki, Hidetoshi Yano, Hidekiyo Ozawa, Seiya Kitagawa, Toshiyuki Matsuyama, Takashi Matsumoto, Kyuichi Takimoto, Yoshiaki Sano
  • Patent number: 6091234
    Abstract: A DC-DC convertor is used as a power source for an electronic apparatus. In this converter, a synchronous rectification transistor is provided in parallel with a flywheel diode. A control circuit of the converter is configured in such a way that a synchronous rectification transistor isolating unit for compulsorily turning off the synchronous rectification transistor for a predetermined fixed period of time, at the activation time of the DC--DC convertor, is included.
    Type: Grant
    Filed: July 30, 1998
    Date of Patent: July 18, 2000
    Assignee: Fujitsu Limited
    Inventor: Seiya Kitagawa
  • Patent number: 5966003
    Abstract: A control circuit for controlling an output voltage of a DC--DC converter which supplies power to various semiconductor device, such as a processor and a memory, by way of an output transistor. The control circuit drives the output transistor in response to an external control signal. The control circuit gradually reduces an operating time of the output transistor by performing a discharge operation in response to the external control signal being inactive.
    Type: Grant
    Filed: February 3, 1998
    Date of Patent: October 12, 1999
    Assignee: Fujitsu Limited
    Inventors: Kyuichi Takimoto, Takashi Matsumoto, Toshiyuki Matsuyama, Seiya Kitagawa
  • Patent number: 5898234
    Abstract: A power supply unit includes a charger composed of a switch for enabling and disabling a charge current and a charge control unit for controlling the switch in accordance with the charge current, the switch being provided in a path shared by the charge current and a discharge current and including a power feed status detection unit for detecting a normal supply voltage of an external power supply source, an absence of a supply of a voltage from the external power supply source, and a drop in a voltage supplied by the external power supply source, and the charge control unit controlling charging of the electric battery by controlling the switch while the power feed status detection unit detects the normal supply voltage of the external power supply source, closing the switch when the power feed status detection unit detects an absence of a supply of a voltage from the external power supply source or a drop in a voltage supplied by the external power supply source, so as to form a discharge path connecting the
    Type: Grant
    Filed: December 3, 1996
    Date of Patent: April 27, 1999
    Assignee: Fujitsu Limited
    Inventor: Seiya Kitagawa
  • Patent number: 5831418
    Abstract: A converter for converting a DC voltage not stabilized, such as the terminal voltage of a battery, into a stable DC voltage, comprising a voltage comparison unit (2 in FIG. 1) and an operation changeover control unit (3). The voltage comparison unit (2) compares an input voltage and an output voltage. The operation changeover control unit (3) controls the changeover of the operations of the DC/DC converter (1) so that the DC/DC converter (1) may perform a step-down operation as the operation of a step-down type converter when the input voltage is higher than the output voltage as the result of the comparison, and that it may perform a step-up operation as the operation of a step-up type converter when the output voltage is higher than the input voltage. Thus, losses in the smoothing reactor and smoothing capacitor of the step-up/down converter are suppressed to enhance the efficiency thereof.
    Type: Grant
    Filed: July 8, 1997
    Date of Patent: November 3, 1998
    Assignee: Fujitsu Ltd.
    Inventor: Seiya Kitagawa