Source: http://www.google.com/patents/US4831325?dq=5,973,252
Timestamp: 2014-07-13 14:38:48
Document Index: 791133351

Matched Legal Cases: ['art 1', 'art 2', 'art 1', 'art 2', 'art 2', 'art 2']

Patent US4831325 - Capacitance measuring circuit - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsA variable capacitor, which may be a humidity sensitive capacitor, and a fixed reference capacitor are connected at a node. The node is clamped at a reference potential during a first phase of a two phase measuring cycle as the variable capacitor is charged to a fixed voltage and the fixed capacitor...http://www.google.com/patents/US4831325?utm_source=gb-gplus-sharePatent US4831325 - Capacitance measuring circuitAdvanced Patent SearchPublication numberUS4831325 APublication typeGrantApplication numberUS 07/032,664Publication dateMay 16, 1989Filing dateApr 1, 1987Priority dateApr 1, 1987Fee statusPaidAlso published asCA1283168C, DE3886244D1, DE3886244T2, EP0285070A1, EP0285070B1Publication number032664, 07032664, US 4831325 A, US 4831325A, US-A-4831325, US4831325 A, US4831325AInventorsCharles W. Watson, Jr.Original AssigneeGeneral Signal CorporationExport CitationBiBTeX, EndNote, RefManPatent Citations (13), Non-Patent Citations (12), Referenced by (52), Classifications (11), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetCapacitance measuring circuitUS 4831325 AAbstract A variable capacitor, which may be a humidity sensitive capacitor, and a fixed reference capacitor are connected at a node. The node is clamped at a reference potential during a first phase of a two phase measuring cycle as the variable capacitor is charged to a fixed voltage and the fixed capacitor is charged to a feedback voltage. The node is unclamped during the second phase and the capacitors are connected in a series loop to allow a redistribution of the charge in the capacitors or force a reversal of that charge with a voltage source. The deviation of the node from its reference potential after charge redistribution occurs is used as input to a feedback circuit which integrates that deviation over a number of cycles until it provides a feedback voltage of magnitude sufficient to cause the node deviation to be reduced to zero. A second reference capacitor can be supplied to provide an offset. The capacitors are constructed by simultaneous deposition on a substrate of a first plate followed by a dielectric film and a second plate. The second plate of the variable capacitor is porous to admit water molecules and the second plate of the fixed capacitor is impervious to water. The simultaneous deposition provides similar characteristics for the capacitors.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS3221247 *Feb 8, 1963Nov 30, 1965Simmonds Precision ProductsSolid state capacity servo measuring system utilizing inductive feedbackUS3903478 *Jul 30, 1974Sep 2, 1975Simmonds Precision ProductsFluid density measuring systemUS4054833 *Jun 11, 1976Oct 18, 1977Setra Systems, Inc.Capacitance measuring systemUS4096758 *May 24, 1977Jun 27, 1978Moore Products Co.Pressure to electric transducerUS4250452 *Apr 19, 1979Feb 10, 1981Motorola, Inc.Pressure sensitive transducer circuitsUS4392378 *Aug 25, 1980Jul 12, 1983501 Ferranti LimitedCapacitance measuring apparatusUS4423371 *Sep 3, 1981Dec 27, 1983Massachusetts Institute Of TechnologyMethods and apparatus for microdielectrometryUS4547725 *Dec 5, 1980Oct 15, 1985Gebruder Buhler AgMethod and apparatus for the continuous determination of moisture pourable foodUS4558595 *Mar 29, 1985Dec 17, 1985Honeywell Inc.Capacitance monitoring bridge circuit for an enthalpy responsive deviceUS4568875 *Jan 6, 1984Feb 4, 1986Micro Sensors IncorporatedMoisture corrected denier measurementUS4656871 *Jul 16, 1985Apr 14, 1987Motorola, Inc.Capacitor sensor and methodGB2020434A * Title not availableJPS61235745A * Title not available* Cited by examinerNon-Patent CitationsReference1"Design of Nonlinear Analog Switched-Capacitor Circuit Building Blocks" by Hosticka et al., IEEE Transactions and Systems; Apr. 1984, pp. 354-367.2 *All MOS Charge Redistribution Analog to Digital Conversion Techniques Part 1 and Part 2, by James L. Creary and Paul R. Gray, IEEE Journal of Solid State Circuits, vol. SC 10, No. 6, Dec. 1975.3All-MOS Charge Redistribution Analog-to-Digital Conversion Techniques--Part 1 and Part 2, by James L. Creary and Paul R. Gray, IEEE Journal of Solid State Circuits, vol. SC-10, No. 6, Dec. 1975.4 *An MOS Switched Capacitor Readout Amplifier for Capacitive Pressure Sensors by Y. E. Park and K. D. Wise, IEEE Proceedings of 1983, Custom Integrated Circuits Conference.5An MOS Switched-Capacitor Readout Amplifier for Capacitive Pressure Sensors by Y. E. Park and K. D. Wise, IEEE Proceedings of 1983, Custom Integrated Circuits Conference.6 *Design of Nonlinear Analog Switched Capacitor Circuit Building Blocks by Hosticka et al., IEEE Transactions and Systems; Apr. 1984, pp. 354 367.7 *Iwai et al.; Capacitance Measurement Circuits in VSLI Structures, IEEE Trans. on Electron Devices, vol. ED 29, No. 10, Oct. 1982, pp. 1622 1626.8Iwai et al.; Capacitance Measurement Circuits in VSLI Structures, IEEE Trans. on Electron Devices, vol. ED-29, No. 10, Oct. 1982, pp. 1622-1626.9 *Matsumoto et al., A Switched Capacitor Digital Capacitance Meter; IEEE Trans on Inst., vol. IM 35, No. 4, Part 2, Dec. 1986, pp. 555 559.10Matsumoto et al., A Switched-Capacitor Digital Capacitance Meter; IEEE Trans on Inst., vol. IM-35, No. 4, Part 2, Dec. 1986, pp. 555-559.11 *Precision Measurement Technique of Integrated MOS Capacitor Mismatching Using a Simple On Chip Circuit by Masakazu Furukawa, Hidetoshi Hatano, and Koji Hanihara, IEEE Trans. on Elect. Dev., vol. ED 33, No. 7, Jul. 1986.12Precision Measurement Technique of Integrated MOS Capacitor Mismatching Using a Simple On-Chip Circuit by Masakazu Furukawa, Hidetoshi Hatano, and Koji Hanihara, IEEE Trans. on Elect. Dev., vol. ED-33, No. 7, Jul. 1986.* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS5170129 *Sep 30, 1991Dec 8, 1992Fuji Xerox Co., Ltd.Charge detecting circuit with variable capacitor and method for sameUS5194819 *Aug 10, 1990Mar 16, 1993Setra Systems, Inc.Linearized capacitance sensor systemUS5235267 *Apr 17, 1990Aug 10, 1993Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V.Circuit and a method for measuring a quantity influencing the capacitance-voltage characteristic of a capacitive elementUS5367264 *May 12, 1993Nov 22, 1994Siemens AgMeasuring instrument and method for determining the alcohol content of a mixtureUS5633594 *Nov 28, 1995May 27, 1997Nec CorporationDifferential type capacitive sensor systemUS5999010 *Dec 8, 1997Dec 7, 1999Simplex Solutions, Inc.Method of measuring interconnect coupling capacitance in an IC chipUS6518766 *Jun 25, 2001Feb 11, 2003Fujitsu Automation LimitedMethod of inspecting an electrical disconnection between circuits by calculating physical quantities thereof based on capacitances regarding the circuits measured twiceUS6724612Jul 9, 2002Apr 20, 2004Honeywell International Inc.Relative humidity sensor with integrated signal conditioningUS6867602Dec 18, 2002Mar 15, 2005Honeywell International Inc.Methods and systems for capacitive balancing of relative humidity sensors having integrated signal conditioningUS6933729 *Mar 15, 2001Aug 23, 2005Micron Technology, Inc.Method and apparatus for measuring on-chip power supply integrityUS7129715 *Sep 30, 2002Oct 31, 2006Ngk Spark Plug Co., Ltd.Oil deterioration sensorUS7205779 *Jan 25, 2005Apr 17, 2007Jennings Thomas AApparatus and method for monitoring and determining the moisture content in elastomer materialsUS7240564 *Jul 30, 2002Jul 10, 2007Alliant Techsystems Inc.Method and apparatus for detecting and determining event characteristics with reduced data collectionUS7375535Sep 19, 2005May 20, 2008Cypress Semiconductor CorporationScan method and topology for capacitive sensingUS7444252 *May 8, 2006Oct 28, 2008Micro Analog Systems OyLinearizer circuitUS7472028Jun 21, 2005Dec 30, 2008Kele Inc.Sensor or capacitance measuring with a microprocessorUS7504833 *Mar 31, 2006Mar 17, 2009Cypress Semiconductor CorporationAutomatically balanced sensing device and method for multiple capacitive sensorsUS7589538 *Dec 21, 2006Sep 15, 2009Weiss Instruments, Inc.Micropower voltage-independent capacitance measuring method and circuitUS7721609Mar 31, 2006May 25, 2010Cypress Semiconductor CorporationMethod and apparatus for sensing the force with which a button is pressedUS7804307Jun 29, 2007Sep 28, 2010Cypress Semiconductor CorporationCapacitance measurement systems and methodsUS7884621Nov 7, 2007Feb 8, 2011Cypress Semiconductor CorporationSuccessive approximate capacitance measurement circuitUS7924028 *Mar 20, 2008Apr 12, 2011Honeywell International Inc.Method and system for adjusting characteristics of integrated relative humidity sensorUS8004497May 18, 2006Aug 23, 2011Cypress Semiconductor CorporationTwo-pin buttonsUS8040142Mar 28, 2007Oct 18, 2011Cypress Semiconductor CorporationTouch detection techniques for capacitive touch sense systemsUS8044671 *Jan 18, 2008Oct 25, 2011Endress + Hauser Gmbh + Co. KgMethod for servicing an apparatus for capacitive ascertaining and/or monitoring of a process variableUS8058884 *Aug 20, 2008Nov 15, 2011Synaptics IncorporatedSystem and method for measuring a capacitance and selectively activating an indicating transducerUS8058937Jan 30, 2007Nov 15, 2011Cypress Semiconductor CorporationSetting a discharge rate and a charge rate of a relaxation oscillator circuitUS8072230Feb 6, 2009Dec 6, 2011Cypress Semiconductor CorporationMethod for compensating for differences in capacitance between multiple capacitive sensorsUS8086417Jul 3, 2008Dec 27, 2011Cypress Semiconductor CorporationNormalizing capacitive sensor array signalsUS8089288Nov 16, 2006Jan 3, 2012Cypress Semiconductor CorporationCharge accumulation capacitance sensor with linear transfer characteristicUS8089289Jul 2, 2008Jan 3, 2012Cypress Semiconductor CorporationCapacitive field sensor with sigma-delta modulatorUS8228076 *Oct 7, 2009Jul 24, 2012Texas Instruments IncorporatedDeconvolution-based capacitive touch detection circuit and methodUS8248084Mar 14, 2011Aug 21, 2012Cypress Semiconductor CorporationTouch detection techniques for capacitive touch sense systemsUS8264244 *Feb 10, 2010Sep 11, 2012Ili Technology Corp.Capacitance difference detecting circuit and capacitance difference detecting methodUS8315832Jun 8, 2011Nov 20, 2012Cypress Semiconductor CorporationNormalizing capacitive sensor array signalsUS8321174Sep 26, 2008Nov 27, 2012Cypress Semiconductor CorporationSystem and method to measure capacitance of capacitive sensor arrayUS8358142Feb 27, 2009Jan 22, 2013Cypress Semiconductor CorporationMethods and circuits for measuring mutual and self capacitanceUS8519973Apr 9, 2012Aug 27, 2013Cypress Semiconductor CorporationApparatus and methods for detecting a conductive object at a locationUS8525798Feb 29, 2008Sep 3, 2013Cypress Semiconductor CorporationTouch sensingUS8536902Nov 21, 2011Sep 17, 2013Cypress Semiconductor CorporationCapacitance to frequency converterUS8547114Nov 14, 2006Oct 1, 2013Cypress Semiconductor CorporationCapacitance to code converter with sigma-delta modulatorUS8564313Sep 12, 2012Oct 22, 2013Cypress Semiconductor CorporationCapacitive field sensor with sigma-delta modulatorUS8570052Oct 31, 2012Oct 29, 2013Cypress Semiconductor CorporationMethods and circuits for measuring mutual and self capacitanceUS8570053Feb 23, 2009Oct 29, 2013Cypress Semiconductor CorporationCapacitive field sensor with sigma-delta modulatorUS8587329 *Apr 13, 2010Nov 19, 2013Balluff GmbhCircuit arrangement for determination of a measuring capacitanceUS8629685 *Oct 29, 2009Jan 14, 2014Continental Automotive FranceDevice for measuring a variation in the capacitance of a variable capacitive structureUS8692563Dec 19, 2012Apr 8, 2014Cypress Semiconductor CorporationMethods and circuits for measuring mutual and self capacitanceUS20100244859 *Oct 7, 2009Sep 30, 2010Texas Instruments IncorporatedDeconvolution-based capacitive touch detection circuit and methodUS20100259284 *Apr 13, 2010Oct 14, 2010Balluff GmbhCircuit arrangement for determination of a measuring capacitanceUS20110115502 *Feb 10, 2010May 19, 2011Kun-Chih LinCapacitance difference detecting circuit and capacitance difference detecting methodUS20110210753 *Oct 29, 2009Sep 1, 2011Continental Automotive FranceDevice for measuring a variation in the capacitance of a variable capacitive structureWO2006081070A1 *Jan 11, 2006Aug 3, 2006Jennings Thomas ADetermining moisture content in flastomer materials* Cited by examinerClassifications U.S. Classification324/678, 324/601, 73/724, 324/679, 324/665International ClassificationG01R27/26, G01N27/22Cooperative ClassificationG01R27/2605, G01N27/225European ClassificationG01R27/26B, G01N27/22C2Legal EventsDateCodeEventDescriptionSep 28, 2000FPAYFee paymentYear of fee payment: 12Sep 20, 1996FPAYFee paymentYear of fee payment: 8Jun 9, 1992FPAYFee paymentYear of fee payment: 4Apr 1, 1987ASAssignmentOwner name: GENERAL SIGNAL CORPORATION, A CORP. OF NYFree format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:WATSON, CHARLES W. JR.;REEL/FRAME:004697/0502Effective date: 19870323RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google