Patents by Inventor Kyoichiro Araki
Kyoichiro Araki 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: 8093876Abstract: A control circuit 10 according to the present invention transits to a first current limiter mode when an output current of a DC-DC converter circuit reaches an upper limit current or greater in a normal mode; transits to the normal mode when the output current falls below the upper limit current in the first current limiter mode; transits to a second current limiter mode when a first predetermined period elapses without a transition to the normal mode in the first current limiter mode; and transits to the normal mode when a second predetermined period elapses in the second current limiter mode.Type: GrantFiled: October 29, 2007Date of Patent: January 10, 2012Assignee: Rohm Co., Ltd.Inventors: Kyoichiro Araki, Hironori Nakahara, Yoshinori Imanaka, Isao Yamamoto
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Publication number: 20110006694Abstract: A control circuit is provided for a separately excited DC/DC converter which directly monitors output voltage to detect a short-circuit state, and performs overcurrent protection. A switching controller of the control circuit controls a switching operation of a switching transistor of the separately excited DC/DC converter. A voltage comparator compares the output voltage and a threshold voltage, to detect the short-circuit state. After a predetermined start-up time has elapsed after beginning start-up of the separately excited DC/DC converter, when the voltage comparator detects the short-circuit state, the switching controller halts the switching operation of the switching transistor, and makes detection of the short-circuit state by the voltage comparator non-operative before elapse of the start-up time.Type: ApplicationFiled: December 6, 2007Publication date: January 13, 2011Applicant: ROHM CO., LTD.Inventors: Yoichi Tamegai, Isao Yamamoto, Kyoichiro Araki
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Patent number: 7868744Abstract: A driving apparatus drives a mover arranged for feedback of a touch panel. A reference voltage generation unit generates a reference voltage having a signal waveform to be applied to the mover. A pulse modulator generates a PWM signal of which duty ratio is controlled by feedback so that a feedback voltage corresponding to a drive voltage to be applied to the mover approaches the reference voltage. A switching element of the DC/DC converter is turned ON/OFF by a PWM signal from the pulse modulator, so that an output voltage of the DC/DC converter is controlled, and a drive voltage corresponding to the output voltage is applied to the mover.Type: GrantFiled: June 13, 2008Date of Patent: January 11, 2011Assignee: Rohm Co., Ltd.Inventors: Kyoichiro Araki, Isao Yamamoto
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Patent number: 7863833Abstract: A control circuit is provided for a separately excited DC/DC converter which directly monitors output voltage to detect a short-circuit state, and performs overcurrent protection. A switching controller of the control circuit controls a switching operation of a switching transistor of the separately excited DC/DC converter. A voltage comparator compares the output voltage and a threshold voltage, to detect the short-circuit state. After a predetermined start-up time has elapsed after beginning start-up of the separately excited DC/DC converter, when the voltage comparator detects the short-circuit state, the switching controller halts the switching operation of the switching transistor, and makes detection of the short-circuit state by the voltage comparator non-operative before elapse of the start-up time.Type: GrantFiled: December 6, 2007Date of Patent: January 4, 2011Assignee: Rohm Co., Ltd.Inventors: Yoichi Tamegai, Isao Yamamoto, Kyoichiro Araki
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Patent number: 7859229Abstract: A discharging device capable of realizing a proper PWM drive by accurately reflecting, as a strobe device, the secondary-side condition of a separately-excited strobe charging circuit being charged. A charging device which charges a main capacitor (2) via a separately-excited DC/DC converter and discharges the energy of the main capacitor, wherein a pulse width control circuit (1) for controlling a conduction pulse width on the primary side of the separately-excited DC/DC converter is provided, and this pulse width control circuit is configured such that a PWM soft start drive is performed that expands a conduction pulse width on the primary side of the separately-excited DC/DC converter stepwise up to a maximum pulse width.Type: GrantFiled: March 29, 2006Date of Patent: December 28, 2010Assignees: Panasonic Photo & Lighting Co., Ltd., Rohm Co., Ltd.Inventors: Hisanori Hoshikawa, Kyoichiro Araki, Isao Yamamoto, Youichi Tamegai
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Publication number: 20100066336Abstract: A control circuit 10 according to the present invention transits to a first current limiter mode when an output current of a DC-DC converter circuit reaches an upper limit current or greater in a normal mode; transits to the normal mode when the output current falls below the upper limit current in the first current limiter mode; transits to a second current limiter mode when a first predetermined period elapses without a transition to the normal mode in the first current limiter mode; and transits to the normal mode when a second predetermined period elapses in the second current limiter mode.Type: ApplicationFiled: October 29, 2007Publication date: March 18, 2010Applicant: ROHM CO., LTD.Inventors: Kyoichiro Araki, Hironori Nakahara, Yoshinori Imanaka, Isao Yamamoto
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Patent number: 7579784Abstract: A control circuit for controlling a switching element in a switching power supply by generating a switching signal is disclosed. The control circuit may include a soft start circuit that generates a switching signal so that an output voltage of the switching power supply gradually increases for a period until the output voltage reaches a predetermined reference voltage. The soft start circuit may increase the output voltage at a first limiting speed when the output voltage is lower than a predetermined threshold voltage, and may increase the output voltage at a second limiting speed which is set higher than the first limiting speed when the output voltage is higher than the threshold voltage.Type: GrantFiled: December 2, 2005Date of Patent: August 25, 2009Assignee: Rohm Co., Ltd.Inventors: Kyoichiro Araki, Yoichi Tamegai, Isao Yamamoto
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Publication number: 20090009144Abstract: A discharging device capable of realizing a proper PWM drive by accurately reflecting, as a strobe device, the secondary-side condition of a separately-excited strobe charging circuit being charged. A charging device which charges a main capacitor (2) via a separately-excited DC/DC converter and discharges the energy of the main capacitor, wherein a pulse width control circuit (1) for controlling a conduction pulse width on the primary side of the separately-excited DC/DC converter is provided, and this pulse width control circuit is configured such that a PWM soft start drive is performed that expands a conduction pulse width on the primary side of the separately-excited DC/DC converter stepwise up to a maximum pulse width.Type: ApplicationFiled: March 29, 2006Publication date: January 8, 2009Applicant: Panasonic Photo & Lighting Co., LtdInventors: Hisanori Hoshikawa, Kyoichiro Araki, Isao Yamamoto, Youichi Tamegai
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Publication number: 20080309467Abstract: A driving apparatus drives a mover arranged for feedback of a touch panel. A reference voltage generation unit generates a reference voltage having a signal waveform to be applied to the mover. A pulse modulator generates a PWM signal of which duty ratio is controlled by feedback so that a feedback voltage corresponding to a drive voltage to be applied to the mover approaches the reference voltage. A switching element of the DC/DC converter is turned ON/OFF by a PWM signal from the pulse modulator, so that an output voltage of the DC/DC converter is controlled, and a drive voltage corresponding to the output voltage is applied to the mover.Type: ApplicationFiled: June 13, 2008Publication date: December 18, 2008Applicant: ROHM CO., LTD.Inventors: Kyoichiro ARAKI, Isao YAMAMOTO
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Publication number: 20080136342Abstract: A control circuit is provided for a separately excited DC/DC converter which directly monitors output voltage to detect a short-circuit state, and performs overcurrent protection. A switching controller of the control circuit controls a switching operation of a switching transistor of the separately excited DC/DC converter. A voltage comparator compares the output voltage and a threshold voltage, to detect the short-circuit state. After a predetermined start-up time has elapsed after beginning start-up of the separately excited DC/DC converter, when the voltage comparator detects the short-circuit state, the switching controller halts the switching operation of the switching transistor, and makes detection of the short-circuit state by the voltage comparator non-operative before elapse of the start-up time.Type: ApplicationFiled: December 6, 2007Publication date: June 12, 2008Applicant: ROHM CO., LTD.Inventors: Yoichi Tamegai, Isao Yamamoto, Kyoichiro Araki
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Publication number: 20080136341Abstract: A control circuit for controlling a switching element in a switching power supply by generating a switching signal is disclosed. The control circuit may include a short start circuit that generates a switching signal so that an output voltage of the switching power supply gradually increases for a period until the output voltage reaches a predetermined reference voltage. The soft start circuit may increase the output voltage at a first limiting speed when the output voltage is lower than a predetermined threshold voltage, and may increase the output voltage at a second limiting speed which is set higher than the first limiting speed when the output voltage is higher than the threshold voltage.Type: ApplicationFiled: December 2, 2005Publication date: June 12, 2008Inventors: Kyoichiro Araki, Yoichi Tamegai, Isao Yamamoto
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Patent number: 7315095Abstract: In a soft start period after power-on, a voltage regulating apparatus checks LED by LED to determine whether the LED is mounted on a position to receive a drive voltage. After the soft start period, the voltage regulating apparatus monitors the driving status of each of the plurality of LEDs. When it is determined as a result of monitoring that the driving status of at least one of the LEDs is improper, the voltage regulating apparatus increases the drive voltage. In this process, the monitoring on an LED determined to be unmounted as a result of a mount checking process is invalidated. With this, it is ensured that a result of monitoring on the LED unmounted is prevented from affecting the increasing of the drive voltage.Type: GrantFiled: March 29, 2005Date of Patent: January 1, 2008Assignee: Rohm Co., Ltd.Inventors: Noboru Kagemoto, Kyoichiro Araki, Isao Yamamoto
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Patent number: 7307385Abstract: A charge pump circuit boosts a voltage of a battery so as to generate a drive voltage for an LED. A constant current circuit generates a constant current to feed through the LED. A monitoring circuit monitors a cathode potential of the LED, i.e., a voltage across the constant current circuit. A control circuit receives a result of monitoring from the monitoring circuit 110 and increases a step-up ratio of the charge pump circuit when the voltage across the constant current circuit drops below a minimum voltage that guarantees a constant current. The control circuit sets an externally requested constant current value in the constant current circuit. When a change from a large current to a small current is requested, the control circuit returns the step-up ratio of the charge pump circuit to 1.0.Type: GrantFiled: March 18, 2005Date of Patent: December 11, 2007Assignee: Rohm Co., Ltd.Inventors: Isao Yamamoto, Kyoichiro Araki, Noboru Kagemoto
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Patent number: 7190195Abstract: An input circuit is provided which prevents malfunctioning of a function circuit during a power source voltage rise without the need of a separate Under Voltage Lock Out (UVLO) circuit.Type: GrantFiled: March 23, 2005Date of Patent: March 13, 2007Assignee: Rohm Co., Ltd.Inventors: Isao Yamamoto, Kyoichiro Araki, Yoichi Tamegai
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Publication number: 20050248322Abstract: In a soft start period after power-on, a voltage regulating apparatus checks LED by LED to determine whether the LED is mounted on a position to receive a drive voltage. After the soft start period, the voltage regulating apparatus monitors the driving status of each of the plurality of LEDs. When it is determined as a result of monitoring that the driving status of at least one of the LEDs is improper, the voltage regulating apparatus increases the drive voltage. In this process, the monitoring on an LED determined to be unmounted as a result of a mount checking process is invalidated. With this, it is ensured that a result of monitoring on the LED unmounted is prevented from affecting the increasing of the drive voltage.Type: ApplicationFiled: March 29, 2005Publication date: November 10, 2005Inventors: Noboru Kagemoto, Kyoichiro Araki, Isao Yamamoto
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Publication number: 20050231127Abstract: A charge pump circuit boosts a voltage of a battery so as to generate a drive voltage for an LED. A constant current circuit generates a constant current to feed through the LED. A monitoring circuit monitors a cathode potential of the LED, i.e., a voltage across the constant current circuit. A control circuit receives a result of monitoring from the monitoring circuit 110 and increases a step-up ratio of the charge pump circuit when the voltage across the constant current circuit drops below a minimum voltage that guarantees a constant current. The control circuit sets an externally requested constant current value in the constant current circuit. When a change from a large current to a small current is requested, the control circuit returns the step-up ratio of the charge pump circuit to 1.0.Type: ApplicationFiled: March 18, 2005Publication date: October 20, 2005Inventors: Isao Yamamoto, Kyoichiro Araki, Noboru Kagemoto
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Publication number: 20050212569Abstract: An input circuit is provided which prevents malfunctioning of a function circuit during a power source voltage rise without the need of a separate Under Voltage Lock Out (UVLO) circuit.Type: ApplicationFiled: March 23, 2005Publication date: September 29, 2005Inventors: Isao Yamamoto, Kyoichiro Araki, Yoichi Tamegai