Patents by Inventor Hirotaka Kawai

Hirotaka Kawai 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: 20240093886
    Abstract: An air conditioner according to an aspect of the present disclosure includes a wall-mounted indoor unit which includes a heat exchanger, a blower, and a housing that accommodates the heat exchanger and the blower therein, and which is fixed to a wall surface, and a discharge unit which is disposed above the indoor unit outside the indoor unit, in which the housing includes a suction port that opens upward, the discharge unit includes a discharge device disposed above the suction port, at least a portion of air suctioned into the suction port passes through the discharge device, and a center of the discharge unit in a right-left direction of the indoor unit is disposed to be shifted to one side in the right-left direction with respect to a center of the indoor unit.
    Type: Application
    Filed: April 20, 2021
    Publication date: March 21, 2024
    Inventors: Reiji MORIOKA, Mitsuhiro SHIROTA, Hirotaka ISHIDA, Shinji KAWAI, Hisanori IKEDA
  • Publication number: 20240077213
    Abstract: An air conditioner according to an aspect of the present disclosure includes a wall-mounted indoor unit which includes a heat exchanger, a blower, and a housing that accommodates the heat exchanger and the blower therein, and which is fixed to a wall surface, and a discharge unit which is disposed above the indoor unit outside the indoor unit, in which the indoor unit includes a first control unit that controls the indoor unit, the housing includes a suction port that opens upward, the discharge unit includes a discharge device disposed above the suction port, at least a portion of air suctioned into the suction port passes through the discharge device, and the discharge device is driven based on a signal received from the first control unit.
    Type: Application
    Filed: April 20, 2021
    Publication date: March 7, 2024
    Inventors: Reiji MORIOKA, Mitsuhiro SHIROTA, Hirotaka ISHIDA, Shinji KAWAI, Hisanori IKEDA
  • Patent number: 8854716
    Abstract: An input/output port, a birefringent element, variable polarization rotator, and a reflector are arranged along an optical axis in the order named. The variable polarization rotator includes permanent magnets for applying a fixed magnetic field to a Faraday rotator in an in-plane direction to magnetically saturate the Faraday rotator and a solenoid coil for applying a variable magnetic field to the Faraday rotator in a direction of the optical axis. A fixed magnetic field is applied in the <211> direction, in which the Faraday rotator is likely to be magnetically saturated. The Faraday rotator can be saturated with a low magnetic field of about 100 Oe. The permanent magnets may employ ferrite permanent magnets, which have weak magnetic forces. A variable magnetic field may also be reduced. Therefore, an air-core coil can be used.
    Type: Grant
    Filed: June 27, 2011
    Date of Patent: October 7, 2014
    Assignee: FDK Corporation
    Inventors: Hiroaki Ono, Hidenori Nakada, Hirotaka Kawai, Yuko Ota, Taro Nakamura
  • Publication number: 20130120824
    Abstract: An input/output port, a birefringent element, variable polarization rotator, and a reflector are arranged along an optical axis in the order named. The variable polarization rotator includes permanent magnets for applying a fixed magnetic field to a Faraday rotator in an in-plane direction to magnetically saturate the Faraday rotator and a solenoid coil for applying a variable magnetic field to the Faraday rotator in a direction of the optical axis. A fixed magnetic field is applied in the <211> direction, in which the Faraday rotator is likely to be magnetically saturated. The Faraday rotator can be saturated with a low magnetic field of about 100 Oe. The permanent magnets may employ ferrite permanent magnets, which have weak magnetic forces. A variable magnetic field may also be reduced. Therefore, an air-core coil can be used.
    Type: Application
    Filed: June 27, 2011
    Publication date: May 16, 2013
    Applicant: FDK CORPORATION
    Inventors: Hiroaki Ono, Hidenori Nakada, Hirotaka Kawai, Yuko Ota, Taro Nakamura
  • Patent number: 8289071
    Abstract: A charge pump includes a switching circuit which is interposed among first and second output capacitors, a flying capacitor, and an input power supply; and a control unit which controls the switching circuit. The charge pump is operated in an operation mode including a high-voltage outputting mode, a low-voltage outputting mode, and a relay mode. The control unit controls the switching circuit so that respective charging voltages of the first and second capacitors that are charged in the high-voltage outputting mode are gradually lowered. The control unit changes the operation mode of the charge pump by relay transition from the high-voltage outputting mode through the relay mode to the low-voltage outputting mode when a voltage lower command is given during a period when the operation mode of the charge pump is in the high-voltage outputting mode.
    Type: Grant
    Filed: September 15, 2010
    Date of Patent: October 16, 2012
    Assignee: Yamaha Corporation
    Inventors: Masato Miyazaki, Hirotaka Kawai, Tatsuya Kishii, Masayoshi Nakamura, Ken Makino
  • Patent number: 8284093
    Abstract: A successive approximation A/D converter, includes a reference voltage generation circuit, a sample/hold circuit, a D/A converter circuit, a comparator, and a control circuit. A potential difference between the comparison target voltage generated by the D/A converter circuit and the internal analog voltage is applied to one input terminal of the comparator through a first signal line, and the reference voltage generation circuit is connected to the other input terminal of the comparator through a second signal line and a switch. Capacitive elements are disposed between the high potential power supply and the second signal line, and between the second signal line and the low potential power supply, respectively. The control circuit turns ON the switch to charge the first and second capacitive elements during a period when the sample/hold circuit samples and holds the internal analog voltage and turns OFF the switch in response to end of the period.
    Type: Grant
    Filed: December 3, 2010
    Date of Patent: October 9, 2012
    Assignee: Yamaha Corporation
    Inventor: Hirotaka Kawai
  • Patent number: 8059834
    Abstract: A controller 100 updates data LVLm indicative of a level section of an input audio signal and controls a reference level Vr based on a signal CMP representative of a comparison result between the input audio signal and the reference level Vr, and further, controls gains of electronic volumes 10L and 10R in such a manner that these gains become such gains corresponding to the level section of the input audio signal. In this case, the level sections of the input audio signals are related to the gains in such a manner that levels of output signals of the electronic volumes do not exceed a previously set output amplitude upper limit level.
    Type: Grant
    Filed: July 6, 2007
    Date of Patent: November 15, 2011
    Assignee: Yamaha Corporation
    Inventors: Yasuomi Tanaka, Nobuaki Tsuji, Hirotaka Kawai
  • Patent number: 7990211
    Abstract: A pulse monitor circuit detects the presence or non-presence of the output pulses output from an output stage circuit. The pulse monitor circuit outputs an up signal to the up/down counter when the output pulses do not exist at all and outputs a down signal to the up/down counter when the output pulses exist. The up/down counter outputs a signal for increasing the delay amount of a delay amount variable circuit when a count value is large, that is, when the output pulses disappear. In contrast, when the count value is small, that is, when the output pulses exist, the counter outputs the signal for reducing the delay amount of the delay amount variable circuit.
    Type: Grant
    Filed: July 11, 2008
    Date of Patent: August 2, 2011
    Assignee: Yamaha Corporation
    Inventors: Hirotaka Kawai, Nobuaki Tsuji, Yasuomi Tanaka
  • Patent number: 7982522
    Abstract: An N-channel transistor is provided as a switch between a high potential power line and a low potential power line. A high-pass filter is constituted by a capacitor and a resistor. When a voltage between the high potential power line and the low potential power line is started to oscillate by a switching operation, the high-pass filter causes a high-pass component thereof to pass, thereby turning ON the N-channel transistor to reduce a ringing.
    Type: Grant
    Filed: January 19, 2010
    Date of Patent: July 19, 2011
    Assignee: Yamaha Corporation
    Inventors: Nobuaki Tsuji, Hirotaka Kawai
  • Publication number: 20110133963
    Abstract: A successive approximation A/D converter, includes a reference voltage generation circuit, a sample/hold circuit, a D/A converter circuit, a comparator, and a control circuit. A potential difference between the comparison target voltage generated by the D/A converter circuit and the internal analog voltage is applied to one input terminal of the comparator through a first signal line, and the reference voltage generation circuit is connected to the other input terminal of the comparator through a second signal line and a switch. Capacitive elements are disposed between the high potential power supply and the second signal line, and between the second signal line and the low potential power supply, respectively. The control circuit turns ON the switch to charge the first and second capacitive elements during a period when the sample/hold circuit samples and holds the internal analog voltage and turns OFF the switch in response to end of the period.
    Type: Application
    Filed: December 3, 2010
    Publication date: June 9, 2011
    Applicant: Yamaha Corporation
    Inventor: Hirotaka Kawai
  • Patent number: 7948313
    Abstract: A class D amplifier circuit includes a signal generation section that generates a first pulse width modulation signal and a second pulse width modulation signal based on an input signal. When a level of the input signal is zero, the signal generation section generates: the first pulse width modulation signal having a repeated first wide-width pulse signal portion, which has a wide width and a repeated first narrow-width pulse signal portion, which has a narrow width which is narrower than the wide width of the first wide-width pulse signal; and the second pulse width modulation signal having a repeated second narrow-width pulse signal portion, which has a narrow width and a repeated second wide-width pulse signal portion, which has a wide width which is wider than the narrow width of the second narrow-width pulse signal portion.
    Type: Grant
    Filed: March 23, 2010
    Date of Patent: May 24, 2011
    Assignee: Yamaha Corporation
    Inventors: Nobuaki Tsuji, Hirotaka Kawai
  • Patent number: 7924089
    Abstract: A class D amplifier includes an input unit that inputs an input signal and an integrator which includes a differential operational amplifier having an offset voltage correction function. The integrator integrates the input signal input. A pulse-width modulator modulates the integration result of the integrator to generate a pulse signal having a pulse width reflective of the integration result. An output unit outputs the pulse signal. A feedback unit superimposes a signal output from the output unit on the input signal and feeds back the superimposed signal to the integrator. An input controller selectively set the input unit to a state where no signal is input. An output controller sets a voltage of an output from the feedback unit to a constant voltage.
    Type: Grant
    Filed: August 30, 2010
    Date of Patent: April 12, 2011
    Assignee: Yamaha Corporation
    Inventors: Yasuomi Tanaka, Nobuaki Tsuji, Hirotaka Kawai
  • Patent number: 7920082
    Abstract: The present invention provides a D/A converter circuit which enables D/A conversion with a high precision and can prevent occurrence of a limit cycle component in the case where an input signal is low, and can also prevent the effect of dither signal from occurring in an analog signal which is a D/A conversion result. A dither signal generation section 505 outputs a dither signal (DITHER) which is an alternating current signal and a reversal dither signal (DITHER_N) inverted from the dither signal. A DEM decoder 502 processes an input digital signal including a component of the dither signal (DITHER), and outputs a plurality of lines of time-series digital signals having a density of “1” or “0” conforming to the input digital signal to be processed. An analog addition section 503 converts a plurality of lines of time-series digital signals and the reversal dither signal (DITHER_N) into an analog signal respectively and adds them, and outputs an analog signal which is a D/A conversion result.
    Type: Grant
    Filed: August 26, 2009
    Date of Patent: April 5, 2011
    Assignee: Yamaha Corporation
    Inventors: Hirotaka Kawai, Nobuaki Tsuji, Morito Morishima, Yohei Otani
  • Publication number: 20110068856
    Abstract: A charge pump includes a switching circuit which is interposed among first and second output capacitors, a flying capacitor, and an input power supply; and a control unit which controls the switching circuit. The charge pump is operated in an operation mode including a high-voltage outputting mode, a low-voltage outputting mode, and a relay mode. The control unit controls the switching circuit so that respective charging voltages of the first and second capacitors that are charged in the high-voltage outputting mode are gradually lowered. The control unit changes the operation mode of the charge pump by relay transition from the high-voltage outputting mode through the relay mode to the low-voltage outputting mode when a voltage lower command is given during a period when the operation mode of the charge pump is in the high-voltage outputting mode.
    Type: Application
    Filed: September 15, 2010
    Publication date: March 24, 2011
    Inventors: Masato Miyazaki, Hirotaka Kawai, Tatsuya Kishii, Masayoshi Nakamura, Ken Makino
  • Patent number: 7912112
    Abstract: A spectrum spreading circuit, includes a control portion that repeats a sequence in which the control portion generates a designation signal for designating all of plural frequencies in prescribed order by selecting a next frequency from the frequencies which have not been selected, and a signal generating portion that sequentially generates output signals having the designated frequencies respectively on the basis of the designation signal.
    Type: Grant
    Filed: July 6, 2007
    Date of Patent: March 22, 2011
    Assignee: Yamaha Corporation
    Inventors: Hirotaka Kawai, Nobuaki Tsuji, Yasuomi Tanaka
  • Publication number: 20110006843
    Abstract: A class D amplifier includes an input unit that inputs an input signal and an integrator which includes a differential operational amplifier having an offset voltage correction function. The integrator integrates the input signal input. A pulse-width modulator modulates the integration result of the integrator to generate a pulse signal having a pulse width reflective of the integration result. An output unit outputs the pulse signal. A feedback unit superimposes a signal output from the output unit on the input signal and feeds back the superimposed signal to the integrator. An input controller selectively set the input unit to a state where no signal is input. An output controller sets a voltage of an output from the feedback unit to a constant voltage.
    Type: Application
    Filed: August 30, 2010
    Publication date: January 13, 2011
    Applicant: Yamaha Corporation
    Inventors: Yasuomi Tanaka, Nobuaki Tsuji, Hirotaka Kawai
  • Patent number: 7830182
    Abstract: A comparator has P-channel field effect transistors that are supplied at respective gates with input voltages Vin and Vref, which are objects of comparison, and that act as a differential transistor pair; and N-channel field effect transistors that serve as current channels for respective drain currents of these two P-channel field effect transistors and that act as a current mirror circuit. The comparator outputs a drain voltage Vx of an N-channel field effect transistor as a signal showing a result of comparison between the two input voltages. An N-channel field effect transistor diode-connected to the comparator is interposed between drains of the N-channel field effect transistors.
    Type: Grant
    Filed: September 19, 2008
    Date of Patent: November 9, 2010
    Assignee: Yamaha Corporation
    Inventors: Masaya Suzuki, Yasuomi Tanaka, Nobuaki Tsuji, Hirotaka Kawai
  • Patent number: 7816992
    Abstract: An offset voltage correction circuit for a differential amplifier comprising NMOS transistors serving as a pair of differential transistors, and PMOS transistors serving as a pair of load transistors connected between outputs of the pair of differential transistors and a power source. The offset voltage correction circuit is equipped with a voltage generator for generating, between a source of any one of the pair of load transistors and the power source, a constant voltage for correcting an offset voltage of the differential amplifier.
    Type: Grant
    Filed: July 6, 2007
    Date of Patent: October 19, 2010
    Assignee: Yamaha Corporation
    Inventors: Yasuomi Tanaka, Nobuaki Tsuji, Hirotaka Kawai
  • Publication number: 20100244958
    Abstract: A class D amplifier circuit includes a signal generation section that generates a first pulse width modulation signal and a second pulse width modulation signal based on an input signal. When a level of the input signal is zero, the signal generation section generates: the first pulse width modulation signal having a repeated first wide-width pulse signal portion, which has a wide width and a repeated first narrow-width pulse signal portion, which has a narrow width which is narrower than the wide width of the first wide-width pulse signal; and the second pulse width modulation signal having a repeated second narrow-width pulse signal portion, which has a narrow width and a repeated second wide-width pulse signal portion, which has a wide width which is wider than the narrow width of the second narrow-width pulse signal portion.
    Type: Application
    Filed: March 23, 2010
    Publication date: September 30, 2010
    Applicant: Yamaha Corporation
    Inventors: Nobuaki Tsuji, Hirotaka Kawai
  • Publication number: 20100164590
    Abstract: An N-channel transistor is provided as a switch between a high potential power line and a low potential power line. A high-pass filter is constituted by a capacitor and a resistor. When a voltage between the high potential power line and the low potential power line is started to oscillate by a switching operation, the high-pass filter causes a high-pass component thereof to pass, thereby turning ON the N-channel transistor to reduce a ringing.
    Type: Application
    Filed: January 19, 2010
    Publication date: July 1, 2010
    Applicant: YAMAHA CORPORATION
    Inventors: NOBUAKI TSUJI, HIROTAKA KAWAI