Patents by Inventor David Dearn
David Dearn 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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Publication number: 20230041143Abstract: There is disclosed a method of improving water quality, the method comprising adding a pool of isolated Daphnia to a body of water such that the pool of isolated Daphnia is exposed to one or more contaminants which may be in the water. The pool of isolated Daphnia comprise Daphnia which have been resurrected from dormant Daphnia. The pool of isolated Daphnia are allowed to filter from the body of water at least a portion of said one or more contaminants to reduce the level of the one or more contaminants in the body of water. After a period of time, at least a portion of the Daphnia containing said one or more contaminants are removed from the body of water, thereby improving the water quality of the body of water.Type: ApplicationFiled: December 9, 2020Publication date: February 9, 2023Inventors: Karl David DEARN, Luisa ORSINI
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Patent number: 10684727Abstract: A touch sensitive screen arrangement includes an optically dispersive base plate and structures for transmitting light onto the base plate in response to an external body touching the screen at a touch point such that the location of incident light on the surface of the base plate is representative of the relative position of the touch point on the screen. The base plate captures and disperses light that is incident on it. The decrease in incident light intensity with distance from the location of incidence on the base plate approximates a substantially exponential function. A sensor detects intensity of light at a respective edge of the base plate. The arrangement calculates the relative position of the touch point on the screen from the detected light intensity and the exponential function and generates a control signal representative of a control input derived from the position of the touch point.Type: GrantFiled: December 5, 2018Date of Patent: June 16, 2020Assignee: Uniphy LimitedInventors: David Dearn, David Lomas
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Publication number: 20190107922Abstract: A touch sensitive screen arrangement includes an optically dispersive base plate and structures for transmitting light onto the base plate in response to an external body touching the screen at a touch point such that the location of incident light on the surface of the base plate is representative of the relative position of the touch point on the screen. The base plate captures and disperses light that is incident on it. The decrease in incident light intensity with distance from the location of incidence on the base plate approximates a substantially exponential function. A sensor detects intensity of light at a respective edge of the base plate. The arrangement calculates the relative position of the touch point on the screen from the detected light intensity and the exponential function and generates a control signal representative of a control input derived from the position of the touch point.Type: ApplicationFiled: December 5, 2018Publication date: April 11, 2019Inventors: David Dearn, David Lomas
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Patent number: 10175822Abstract: A touch sensitive screen arrangement includes an optically dispersive base plate and structures for transmitting light onto the base plate in response to an external body touching the screen at a touch point such that the location of incident light on the surface of the base plate is representative of the relative position of the touch point on the screen. The base plate captures and disperses light that is incident on it. The decrease in incident light intensity with distance from the location of incidence on the base plate approximates a substantially exponential function. A sensor detects intensity of light at a respective edge of the base plate. The arrangement calculates the relative position of the touch point on the screen from the detected light intensity and the exponential function and generates a control signal representative of a control input derived from the position of the touch point.Type: GrantFiled: April 1, 2015Date of Patent: January 8, 2019Assignee: T-Phy Ltd.Inventors: David Dearn, David Lomas
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Publication number: 20170031527Abstract: A touch sensitive screen arrangement includes an optically dispersive base plate and structures for transmitting light onto the base plate in response to an external body touching the screen at a touch point such that the location of incident light on the surface of the base plate is representative of the relative position of the touch point on the screen. The base plate captures and disperses light that is incident on it. The decrease in incident light intensity with distance from the location of incidence on the base plate approximates a substantially exponential function. A sensor detects intensity of light at a respective edge of the base plate. The arrangement calculates the relative position of the touch point on the screen from the detected light intensity and the exponential function and generates a control signal representative of a control input derived from the position of the touch point.Type: ApplicationFiled: April 1, 2015Publication date: February 2, 2017Inventors: David DEARN, David LOMAS
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Patent number: 9153987Abstract: A battery charger voltage control method dynamically adjusts the system voltage generated by a battery charger circuit based on the operating conditions to ensure that sufficient power is supplied to power up the circuitry of the electronic device when the battery charger circuit is connected to a current-limited power source and the battery of the electronic device is deeply depleted or is missing. In embodiments of the present invention, the battery charger voltage control method sets the system voltage to an elevated voltage value to maximize the energy transfer from the power source to the circuitry of the electronic device. In this manner, the battery charger voltage control method enables a near instant boot-up of the electronic device, even under the operating conditions where the battery of the electronic device is deeply depleted or missing and the switching battery charger circuit can only receive power from a current-limited power source.Type: GrantFiled: March 7, 2012Date of Patent: October 6, 2015Assignee: Micrel, Inc.Inventors: Ken Mok, David Dearn
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Patent number: 8773084Abstract: A DC-to-DC, buck-boost voltage converter includes a duty cycle controller configured to generate control signals for a buck driver configured to drive first and second buck switching transistors at a buck duty cycle and to generate control signals for a boost driver configured to drive first and second boost switching transistors at a boost duty cycle. The duty cycle controller includes at least a duty cycle timer and an offset timer where the duty cycle controller applies the duty cycle timer and the offset timer to control transitions between the buck, the buck-boost and the boost operation modes of the voltage converter.Type: GrantFiled: October 20, 2011Date of Patent: July 8, 2014Assignee: Micrel, Inc.Inventors: Charles A. Casey, David Dearn
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Publication number: 20130234677Abstract: A battery charger voltage control method dynamically adjusts the system voltage generated by a battery charger circuit based on the operating conditions to ensure that sufficient power is supplied to power up the circuitry of the electronic device when the battery charger circuit is connected to a current-limited power source and the battery of the electronic device is deeply depleted or is missing. In embodiments of the present invention, the battery charger voltage control method sets the system voltage to an elevated voltage value to maximize the energy transfer from the power source to the circuitry of the electronic device. In this manner, the battery charger voltage control method enables a near instant boot-up of the electronic device, even under the operating conditions where the battery of the electronic device is deeply depleted or missing and the switching battery charger circuit can only receive power from a current-limited power source.Type: ApplicationFiled: March 7, 2012Publication date: September 12, 2013Applicant: MICREL, INC.Inventors: Ken Mok, David Dearn
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Patent number: 8436591Abstract: In a buck-boost converter, the method compensates for the boost mode power switch having a minimum on-time when entering the buck-boost mode from the buck mode by immediately decreasing a duty cycle of the buck mode power switch upon entering the buck-boost mode. This prevents the inductor current from being higher at the end of the switching cycle than at the beginning of the cycle, so the output voltage stays regulated without the converter oscillating between the buck mode and the buck-boost mode. The duty cycle of the buck power switch is increased in the buck-boost mode as the input voltage further falls and the boost power switch duty cycle is increased. Upon transitioning into the boost mode, the duty cycle of the boost power switch is immediately reduced to compensate for the buck switching being stopped and the buck power switch having a minimum off-time.Type: GrantFiled: August 24, 2009Date of Patent: May 7, 2013Assignee: Micrel, Inc.Inventor: David Dearn
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Publication number: 20120032658Abstract: A DC-to-DC, buck-boost voltage converter includes a duty cycle controller configured to generate control signals for a buck driver configured to drive first and second buck switching transistors at a buck duty cycle and to generate control signals for a boost driver configured to drive first and second boost switching transistors at a boost duty cycle. The duty cycle controller includes at least a duty cycle timer and an offset timer where the duty cycle controller applies the duty cycle timer and the offset timer to control transitions between the buck, the buck-boost and the boost operation modes of the voltage converter.Type: ApplicationFiled: October 20, 2011Publication date: February 9, 2012Applicant: MICREL, INC.Inventors: Charles A. Casey, David Dearn
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Patent number: 8085005Abstract: In an average-current mode control type buck-boost PWM converter, a sample and hold circuit is inserted in the current loop to avoid problems associated with ripple of the average inductor current demand signal. The rippling average inductor current is generated by a differential transconductance amplifier having applied to its inputs an error signal and a signal corresponding to the instantaneous current through the inductor, where the output of the amplifier is filtered. The rippling average inductor current is sampled and held at the beginning of each switching cycle, prior to the average inductor current demand signal being compared to buck and boost sawtooth waveforms. By using the sample and hold circuit, the feedback loops are easier to stabilize, and the converter cannot switch modes during a switching cycle.Type: GrantFiled: June 18, 2009Date of Patent: December 27, 2011Assignee: Micrel, Inc.Inventor: David Dearn
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Publication number: 20110043172Abstract: In a buck-boost converter, the method compensates for the boost mode power switch having a minimum on-time when entering the buck-boost mode from the buck mode by immediately decreasing a duty cycle of the buck mode power switch upon entering the buck-boost mode. This prevents the inductor current from being higher at the end of the switching cycle than at the beginning of the cycle, so the output voltage stays regulated without the converter oscillating between the buck mode and the buck-boost mode. The duty cycle of the buck power switch is increased in the buck-boost mode as the input voltage further falls and the boost power switch duty cycle is increased. Upon transitioning into the boost mode, the duty cycle of the boost power switch is immediately reduced to compensate for the buck switching being stopped and the buck power switch having a minimum off-time.Type: ApplicationFiled: August 24, 2009Publication date: February 24, 2011Applicant: MICREL, INC.Inventor: David Dearn
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Publication number: 20100320992Abstract: In an average-current mode control type buck-boost PWM converter, a sample and hold circuit is inserted in the current loop to avoid problems associated with ripple of the average inductor current demand signal. The rippling average inductor current is generated by a differential transconductance amplifier having applied to its inputs an error signal and a signal corresponding to the instantaneous current through the inductor, where the output of the amplifier is filtered. The rippling average inductor current is sampled and held at the beginning of each switching cycle, prior to the average inductor current demand signal being compared to buck and boost sawtooth waveforms. By using the sample and hold circuit, the feedback loops are easier to stabilize, and the converter cannot switch modes during a switching cycle.Type: ApplicationFiled: June 18, 2009Publication date: December 23, 2010Applicant: Micrel, Inc.Inventor: David Dearn
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Patent number: 7605574Abstract: A current-mode switching regulator including at least: an inductor; a main switch for controlling the current flow through the inductor; and a feedback control circuit for operating the main switch cyclically and to vary a duty cycle of the main switch so as to substantially maintain an output voltage of the regulator at a desired level. The feedback control circuit further includes slope compensation circuitry adding slope compensation to a signal representing the inductor current prior to the slope compensated signal being compared to the fed-back output error voltage.Type: GrantFiled: April 16, 2007Date of Patent: October 20, 2009Assignee: Wolfson Microelectronics plcInventors: David Dearn, Holger Haiplik
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Patent number: 7573152Abstract: The present invention provides a self-contained power management device, such as a power management IC or an IC including power management functions, which allow sequenced start up of power supplies without the need for an external sequencer and with a simple user configurable arrangement.Type: GrantFiled: April 9, 2007Date of Patent: August 11, 2009Assignee: Wolfson Microelectronics plcInventors: Mark Jacob, John Pennock, David Dearn
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Publication number: 20080024108Abstract: The present invention provides a self-contained power management device, such as a power management IC or an IC including power management functions, which allow sequenced start up of power supplies without the need for an external sequencer and with a simple user configurable arrangement.Type: ApplicationFiled: April 9, 2007Publication date: January 31, 2008Inventors: Mark Jacob, John Pennock, David Dearn
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Patent number: 7301347Abstract: A current sensing circuit for sensing the current through a main switch, such as the PMOS or NMOS switches of a switching regulator, is disclosed. The circuit includes a mirror switch, said mirror switch being substantially similar to said main switch but with a smaller aspect ratio, a difference amplifier for ensuring that the voltage across said first leg and across said second leg are substantially equal and thereby to derive from said mirror switch a sensing current nominally equal to a current flowing in said main switch divided by a sensing ratio, a current source for producing a quiescent current in said difference amplifier and a compensatory device for compensating for said quiescent current such that said current sensing circuit can sense currents in the main switch which are smaller than the quiescent current multiplied by the sensing ratio. The compensatory device may be one or two switches essentially similar to the mirror switch.Type: GrantFiled: December 28, 2005Date of Patent: November 27, 2007Assignee: Wolfson Microelectronics plcInventors: David Dearn, Holger Haiplik
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Publication number: 20070252567Abstract: A current-mode switching regulator including at least: an inductor; a main switch for controlling the current flow through the inductor; and a feedback control circuit for operating the main switch cyclically and to vary a duty cycle of the main switch so as to substantially maintain an output voltage of the regulator at a desired level. The feedback control circuit further includes slope compensation circuitry adding slope compensation to a signal representing the inductor current prior to the slope compensated signal being compared to the fed-back output error voltage.Type: ApplicationFiled: April 16, 2007Publication date: November 1, 2007Inventors: David Dearn, Holger Haiplik
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Publication number: 20070096748Abstract: A current sensing circuit for sensing the current through a main switch, such as the PMOS or NMOS switches of a switching regulator, is disclosed. The circuit comprises a mirror switch, said mirror switch being substantially similar to said main switch but with a smaller aspect ratio, a difference amplifier for ensuring that the voltage across said first leg and across said second leg are substantially equal and thereby to derive from said mirror switch a sensing current nominally equal to a current flowing in said main switch divided by a sensing ratio, a current source for producing a quiescent current in said difference amplifier and a compensatory device for compensating for said quiescent current such that said current sensing circuit can sense currents in the main switch which are smaller than the quiescent current multiplied by the sensing ratio. The compensatory device may be one or two switches essentially similar to the mirror switch.Type: ApplicationFiled: December 28, 2005Publication date: May 3, 2007Inventors: David Dearn, Holger Haiplik
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Patent number: 6856124Abstract: A method and a circuit to achieve a low drop-out voltage regulator with a wide output load range has been achieved. A fast loop is introduced in the circuit. The circuit is internally compensated and uses a capacitor to ensure that the internal pole is more dominant than the output pole as in standard Miller compensation. The quiescent current is set being proportional to the output load current. No explicit low power drive stage is required. The whole output range is covered by one output drive stage. By that means the total consumption of quiescent or wasted current is reduced. An excellent PSRR is achieved due to load dependent bias current.Type: GrantFiled: July 9, 2002Date of Patent: February 15, 2005Assignee: Dialog Semiconductor GmbHInventors: David Dearn, John Stuart Malcolm, Axel Pannwitz