Patents by Inventor Yuusuke Michishita
Yuusuke Michishita 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: 9431907Abstract: A switching regulator includes a first switching element and a second switching element in a pair to be switched over to convert an input voltage to a certain constant voltage, and an operation monitor to monitor an operation state of the first switching element, in which a switching of the second switching element is changed according to a result of the monitoring by the operation monitor.Type: GrantFiled: August 18, 2014Date of Patent: August 30, 2016Assignee: RICOH ELECTRONIC DEVICES CO., LTD.Inventor: Yuusuke Michishita
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Patent number: 9071125Abstract: A switching regulator configured to convert an input voltage input to an input terminal into a predetermined constant voltage by switching with at least two elements including a pair of switching elements or a switching element and a rectifying element, and output the converted voltage as an output voltage from an output terminal includes a comparison unit configured to compare a signal showing an oscillating frequency of the switching regulator with a signal showing a constant frequency, and a driver configured to delay a pulse signal generated by feeding-back a control signal and an output signal of the switching regulator according to the comparison result by the comparison unit with a predetermined time, and switch the input voltage by using the at least two elements based on the pulse signal after the delay.Type: GrantFiled: February 7, 2013Date of Patent: June 30, 2015Assignee: RICOH ELECTRONIC DEVICES CO., LTD.Inventor: Yuusuke Michishita
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Publication number: 20150061615Abstract: A switching regulator includes a first switching element and a second switching element in a pair to be switched over to convert an input voltage to a certain constant voltage, and an operation monitor to monitor an operation state of the first switching element, in which a switching of the second switching element is changed according to a result of the monitoring by the operation monitor.Type: ApplicationFiled: August 18, 2014Publication date: March 5, 2015Applicant: RICOH COMPANY, LTD.Inventor: Yuusuke Michishita
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Patent number: 8829876Abstract: A non-isolated type switching regulator having an inductor includes: a switch element; a rectification element; an error amplifying circuit section amplifying a voltage difference between a feedback voltage and a first reference voltage and outputting as an error voltage; a first voltage comparison circuit section performing a voltage comparison of a ramp voltage which performs a voltage change set beforehand with the error voltage to be synchronized with the switching of the switch element and producing and outputting a first comparison signal; a second voltage comparison circuit performing a voltage comparison of the error voltage with a second reference voltage and producing and outputting a second comparison signal; an oscillation circuit section starting an oscillation based on the second comparison signal and producing and outputting a clock signal; and a control circuit section performing a switching control of the switch element based on the clock signal and the first comparison signal.Type: GrantFiled: April 20, 2010Date of Patent: September 9, 2014Assignee: Ricoh Company, Ltd.Inventors: Yuusuke Michishita, Shinya Shimizu
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Patent number: 8797014Abstract: A DC-DC converter to convert an input voltage into a predetermined voltage includes a first switching device to provide energy for an inductor; a second switching device to discharge the energy from the inductor to an output terminal; an error amplifier to amplify an error voltage between a first reference voltage and a monitoring voltage obtained by dividing an output voltage output from the output terminal; a set signal generation circuit including a first comparator into which a second reference voltage and an output of the error amplifier are input; a reset signal generation circuit; a control circuit into which an output from the set signal generation circuit and an output from the reset signal generation circuit are input; and a detection circuit to detect a switching frequency of an electric power supply, wherein a characteristic of the first comparator is changed according to the switching frequency.Type: GrantFiled: September 14, 2009Date of Patent: August 5, 2014Assignee: Ricoh Company, Ltd.Inventors: Yuusuke Michishita, Shinya Shimizu
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Patent number: 8581567Abstract: In a switching regulator, a peak current value of an inductor current iL corresponding to a critical current is obtained by {(Vin?Vout)/Vin×Vout/L×Ts}, where Ts is the frequency of clock signals CLK constituting set pulses generated at predetermined timings by an oscillating circuit 9. Accordingly, by setting a reference voltage VLL as (Vout/L×Ts/rs), the peak current value of the inductor current iL when the load current has decreased is set to be the peak current value of the inductor current iL corresponding to the critical current. Therefore, simply by setting the reference voltage VLL in advance, the peak current of the inductor current iL when the load current has decreased is set to be the peak current value of the inductor current iL corresponding to the critical current.Type: GrantFiled: May 21, 2009Date of Patent: November 12, 2013Assignee: Ricoh Company, Ltd.Inventors: Shinya Shimizu, Yuusuke Michishita
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Publication number: 20130208520Abstract: A switching regulator configured to convert an input voltage input to an input terminal into a predetermined constant voltage by switching with at least two elements including a pair of switching elements or a switching element and a rectifying element, and output the converted voltage as an output voltage from an output terminal includes a comparison unit configured to compare a signal showing an oscillating frequency of the switching regulator with a signal showing a constant frequency, and a driver configured to delay a pulse signal generated by feeding-back a control signal and an output signal of the switching regulator according to the comparison result by the comparison unit with a predetermined time, and switch the input voltage by using the at least two elements based on the pulse signal after the delay.Type: ApplicationFiled: February 7, 2013Publication date: August 15, 2013Applicant: RICOH COMPANY, LTD.Inventor: Yuusuke Michishita
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Patent number: 8319487Abstract: A novel voltage regulator includes an indictor, a switching transistor, a rectifier, an error amplifier circuit, a first voltage comparator circuit, a second voltage comparator circuit, an oscillator circuit, and a driver circuit. The first voltage comparator circuit outputs a modulation signal. The second voltage comparator circuit activates an enable signal when the error voltage exceeds the second reference voltage. The oscillator circuit outputs a clock signal with a fixed frequency according to the enable signal. The oscillator circuit enters a first state when the enable signal is activated and deactivated within a period of time shorter than a threshold time, and enters a second state when the enable signal remains activated during a period of time longer than the threshold time. The driver circuit generates the switching control signal based on the clock signal and the modulation signal.Type: GrantFiled: September 4, 2009Date of Patent: November 27, 2012Assignee: Ricoh Company, Ltd.Inventors: Yuusuke Michishita, Shinya Shimizu
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Patent number: 8242764Abstract: A non-isolated DC-DC converter that converts a voltage input to an input terminal to output a constant output voltage to a load terminal while switching control mode between a PWM mode and a VFM mode depending on a current output to the load terminal. The DC-DC converter includes an inductor, a switching circuit, and a control circuit. The inductor stores electric energy for supply to the load terminal. The switching circuit switches on and off current flow at a switching frequency to alternately charge and discharge the inductor. The control circuit increases an electric current flowing to the load terminal through the inductor per one operational cycle as the switching frequency decreases during VFM control mode operation.Type: GrantFiled: September 11, 2009Date of Patent: August 14, 2012Assignee: Ricoh Company, Ltd.Inventors: Shinya Shimizu, Yuusuke Michishita
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Publication number: 20120038341Abstract: A non-isolated type switching regulator having an inductor includes: a switch element; a rectification element; an error amplifying circuit section amplifying a voltage difference between a feedback voltage and a first reference voltage and outputting as an error voltage; a first voltage comparison circuit section performing a voltage comparison of a ramp voltage which performs a voltage change set beforehand with the error voltage to be synchronized with the switching of the switch element and producing and outputting a first comparison signal; a second voltage comparison circuit performing a voltage comparison of the error voltage with a second reference voltage and producing and outputting a second comparison signal; an oscillation circuit section starting an oscillation based on the second comparison signal and producing and outputting a clock signal; and a control circuit section performing a switching control of the switch element based on the clock signal and the first comparison signal.Type: ApplicationFiled: April 20, 2010Publication date: February 16, 2012Inventors: Yuusuke Michishita, Shinya Shimizu
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Publication number: 20110169464Abstract: A DC-DC converter to convert an input voltage into a predetermined voltage includes a first switching device to provide energy for an inductor; a second switching device to discharge the energy from the inductor to an output terminal; an error amplifier to amplify an error voltage between a first reference voltage and a monitoring voltage obtained by dividing an output voltage output from the output terminal; a set signal generation circuit including a first comparator into which a second reference voltage and an output of the error amplifier are input; a reset signal generation circuit; a control circuit into which an output from the set signal generation circuit and an output from the reset signal generation circuit are input; and a detection circuit to detect a switching frequency of an electric power supply, wherein a characteristic of the first comparator is changed according to the switching frequency.Type: ApplicationFiled: September 14, 2009Publication date: July 14, 2011Applicant: RICOH COMPANY, LTD.Inventors: Yuusuke Michishita, Shinya Shimizu
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Patent number: 7852055Abstract: A switching regulator includes a switching transistor to switch in accordance with an input control signal, an inductor charged with an input voltage in response to a switching operation by the switching transistor, a switch signal generator to detect an inductor current flowing through the inductor from a voltage at a connection point between the switching transistor and the inductor and output a predetermined switch signal after a time in accordance with the input voltage when detecting the inductor current is zero, and a controller to perform a PWM control or a PFM control on the switching transistor in accordance with the switch signal output from the switch signal generator to keep an output voltage output from the output terminal at a predetermined constant voltage. The controller performs the PFM control when the predetermined switch signal is continuously input thereto from the switch signal generator one or more times.Type: GrantFiled: February 13, 2008Date of Patent: December 14, 2010Assignee: Ricoh Company, Ltd.Inventor: Yuusuke Michishita
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Publication number: 20100066328Abstract: A non-isolated DC-DC converter that converts a voltage input to an input terminal to output a constant output voltage to a load terminal while switching control mode between a PWM mode and a VFM mode depending on a current output to the load terminal. The DC-DC converter includes an inductor, a switching circuit, and a control circuit. The inductor stores electric energy for supply to the load terminal. The switching circuit switches on and off current flow at a switching frequency to alternately charge and discharge the inductor. The control circuit increases an electric current flowing to the load terminal through the inductor per one operational cycle as the switching frequency decreases during VFM control mode operation.Type: ApplicationFiled: September 11, 2009Publication date: March 18, 2010Applicant: RICOH COMPANY, LTD.Inventors: Shinya SHIMIZU, Yuusuke MICHISHITA
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Publication number: 20090322299Abstract: A novel voltage regulator includes an indictor, a switching transistor, a rectifier, an error amplifier circuit, a first voltage comparator circuit, a second voltage comparator circuit, an oscillator circuit, and a driver circuit. The first voltage comparator circuit outputs a modulation signal. The second voltage comparator circuit activates an enable signal when the error voltage exceeds the second reference voltage. The oscillator circuit outputs a clock signal with a fixed frequency according to the enable signal. The oscillator circuit enters a first state when the enable signal is activated and deactivated within a period of time shorter than a threshold time, and enters a second state when the enable signal remains activated during a period of time longer than the threshold time. The driver circuit generates the switching control signal based on the clock signal and the modulation signal.Type: ApplicationFiled: September 4, 2009Publication date: December 31, 2009Applicant: RICOH COMPANY, LTD.Inventors: Yuusuke Michishita, Shinya Shimizu
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Publication number: 20090302820Abstract: In a switching regulator, a peak current value of an inductor current iL corresponding to a critical current is obtained by {(Vin?Vout)/Vin×Vout/L×Ts}, where Ts is the frequency of clock signals CLK constituting set pulses generated at predetermined timings by an oscillating circuit 9. Accordingly, by setting a reference voltage VLL as (Vout/L×Ts/rs), the peak current value of the inductor current iL when the load current has decreased is set to be the peak current value of the inductor current iL corresponding to the critical current. Therefore, simply by setting the reference voltage VLL in advance, the peak current of the inductor current iL when the load current has decreased is set to be the peak current value of the inductor current iL corresponding to the critical current.Type: ApplicationFiled: May 21, 2009Publication date: December 10, 2009Applicant: RICOH COMPANY, LTD.Inventors: Shinya SHIMIZU, Yuusuke Michishita
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Publication number: 20090174384Abstract: A disclosed switching regulator converts an input voltage to an output voltage of a predetermined level and outputs the output voltage. The disclosed switching regulator includes a switching transistor configured to be turned on and off according to a control signal; an inductor configured to be charged by the input voltage when the switching transistor is turned on; a mode switching circuit configured to generate a switching signal for switching a control mode of the switching transistor between a PWM control mode and a VFM control mode; and a control circuit configured to control the switching transistor in the PWM control mode or the VFM control mode depending on the switching signal from the mode switching circuit so that the output voltage is maintained at the predetermined level.Type: ApplicationFiled: February 5, 2008Publication date: July 9, 2009Inventors: Yuusuke Michishita, Junji Nishida
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Patent number: 7479773Abstract: A synchronous rectification switching regulator includes a reverse current prevention circuit unit that detects a symptom of a reverse current flowing in a direction from an output terminal to a second switching element or a generation of the reverse current based on a voltage of a connecting portion for connecting the second switching element with a third switching element. The reverse current prevention circuit unit turns off the third switching element to interrupt the reverse current when the reverse current prevention circuit unit detects the symptom or the generation of the reverse current.Type: GrantFiled: September 4, 2007Date of Patent: January 20, 2009Assignee: Ricoh Company, Ltd.Inventor: Yuusuke Michishita
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Publication number: 20080197828Abstract: A switching regulator includes a switching transistor to switch in accordance with an input control signal, an inductor charged with an input voltage in response to a switching operation by the switching transistor, a switch signal generator to detect an inductor current flowing through the inductor from a voltage at a connection point between the switching transistor and the inductor and output a predetermined switch signal after a time in accordance with the input voltage when detecting the inductor current is zero, and a controller to perform a PWM control or a PFM control on the switching transistor in accordance with the switch signal output from the switch signal generator to keep an output voltage output from the output terminal at a predetermined constant voltage. The controller performs the PFM control when the predetermined switch signal is continuously input thereto from the switch signal generator one or more times.Type: ApplicationFiled: February 13, 2008Publication date: August 21, 2008Inventor: Yuusuke Michishita
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Publication number: 20080061755Abstract: A synchronous rectification switching regulator includes a reverse current prevention circuit unit that detects a symptom of a reverse current flowing in a direction from an output terminal to a second switching element or a generation of the reverse current based on a voltage of a connecting portion for connecting the second switching element with a third switching element. The reverse current prevention circuit unit turns off the third switching element to interrupt the reverse current when the reverse current prevention circuit unit detects the symptom or the generation of the reverse current.Type: ApplicationFiled: September 4, 2007Publication date: March 13, 2008Inventor: Yuusuke Michishita