Including A Bridge Circuit Patents (Class 324/706)
  • Patent number: 7126355
    Abstract: A physical quantity sensing device includes an AC voltage generator for generating an AC voltage and a bridge circuit that has first and second input points, to which the AC voltage is applied, and first and second output points connected to a differential amplifier. The bridge circuit includes first and second sensor elements, the impedance of which change with a physical quantity to be measured. The first and second sensor elements have a positive temperature characteristic in which sensitivity increases as temperature rises. The AC voltage generator includes an amplitude limiter which has a negative temperature characteristic that decreases the amplitude of the AC voltage with a rise in temperature, thereby compensating for temperature dependence of a differential voltage produced between the first and second output points.
    Type: Grant
    Filed: May 18, 2005
    Date of Patent: October 24, 2006
    Assignee: Yamaha Hatsudoki Kabushiki Kaisha
    Inventor: Kenji Seto
  • Patent number: 7088108
    Abstract: In a method for detecting an offset drift in a resistive Wheatstone measuring bridge, a switch is made between a measuring mode and a testing mode without interfering in the internal structure of the measuring bridge. In testing mode, two sensor resistors that act in the same way and lie in different bridge arms in the measuring mode are connected in series, and a voltage level occurring in the connection of these sensor resistors is compared with a reference voltage. Preferably the sensor resistor that acts in a different way and lies between the two series-connected sensor resistors acting in the same way is bridged. The reference voltage is advantageously formed by resistive division of the voltage applied to the series connection of the sensor resistors. The testing mode may expediently be switched in such a way that the two pairs of sensor resistors acting in the same way are respectively tested in succession.
    Type: Grant
    Filed: February 18, 2005
    Date of Patent: August 8, 2006
    Assignees: Fraunhofer-Gesellschaft zur Forderung der angewandten Forschung e.V., Intelligente Sensorsysteme Dresden GmbH
    Inventors: Peter König, Stefan Krone, Stefan Woschech, Matthias Böhm, Andreas Schroth
  • Patent number: 6984995
    Abstract: An Audio Feedback Impedance Comparison Device to audibly express Impedance differences between/amongst components, circuits, materials, substances etc., to make use of the aural sense, while relieving eye, neck and mental strain, as well as reduce probe time. This is achieved by allowing simultaneous yet focused attention to be paid to all aspects of an impedance probe, i.e. hand-eye coordination of probe positioning, while aurally monitoring the feedback, instead of the common practices/methods where eyes have to be re-focused on visual feedback devices. The use of an alternating signal allows “through” comparison, where multiple components some of which are impervious to static signal, contribute to overall impedance. The device can be used to inject and/or detect/trace the presence of an audio signal in an active circuit. With the aid of transducers, this Device may be used with other forms of energy.
    Type: Grant
    Filed: August 29, 2001
    Date of Patent: January 10, 2006
    Inventor: Clifton Lawrence
  • Patent number: 6807843
    Abstract: The gas sensor may be an apparatus for sensing a proportion of a gas in a gas mixture. A gas sensor may have a sampling element slidably engaged with a sensor element. The sensor element may have a sensing chamber therein with an inlet passage and an outlet passage formed in the sensor element wherein the inlet passage and the outlet passage may be in communication with the sensing chamber and externally to the sensor element. A first detector may be positioned in the sensing chamber with a first pair of external contacts passing through the sensor element terminating externally thereto. The sensor element may have a reference chamber therein with a second detector positioned therein and a second pair of external contacts passing through the sensor element terminating externally thereto. The sampling element may have a sample chamber therein with the sensor element forming a portion of the sample chamber.
    Type: Grant
    Filed: October 11, 2003
    Date of Patent: October 26, 2004
    Assignee: C-Squared, Inc.
    Inventor: David Lee Hawe
  • Patent number: 6803776
    Abstract: A current comparator technique is applied to four-terminal resistance measurements for obtaining a highly accurate AC resistance bridge at power frequencies of 50 Hz to 60 Hz. Active circuits are used to establish equal voltage drops between the potential terminals of the two resistances being compared. The bridge is suitable for measuring resistances from 10 &mgr;&OHgr; to 100 k&mgr;&OHgr;. A cascading technique using two two-stage current transformers provides extension of the ratio range to 100,00,000 with a maximum applied current of 10,000 A. The bridge features measurement with a resolution of 0.1×10−6. The total combined uncertainty (2&sgr;) of the bridge including the range extenders, at power frequencies, is estimated to be less than 5 &mgr;&OHgr;/&OHgr;.
    Type: Grant
    Filed: March 14, 2002
    Date of Patent: October 12, 2004
    Assignee: National Research Council of Canada
    Inventors: Eddy So, Branislav Djokic
  • Patent number: 6765391
    Abstract: An ASIC (14, 14′, 14″) conditions two independent outputs (VINM, VINP) of a full Wheatstone piezoresistive bridge (12) in separate conditioning paths. Each path is provided with a bridge supply voltage (VHB1, VHB2) which can serve as a temperature related input signal to respective offset and gain compensation control circuits. The half bridge outputs are inputted to respective amplifiers (U1, U2) along with a selected percentage of the temperature dependent bridge supply voltage. The outputs of the amplifiers provide a signal proportional to respective half bridge output voltage. In one embodiment, the output of the amplifier (U2) in one conditioning path of one half bridge is connected to the input of an amplifier (U4) in the other conditioning path to provide a signal in the one path proportional to the Wheatstone bridge differential output voltage and in the other path a signal proportional to the Wheatstone half bridge output voltage.
    Type: Grant
    Filed: October 22, 2002
    Date of Patent: July 20, 2004
    Assignee: Texas Instruments Incorporated
    Inventors: David L. Corkum, Keith W. Kawate, Thomas R. Maher
  • Publication number: 20040075447
    Abstract: An ASIC (14, 14′, 14″) conditions two independent outputs (VINM, VINP) of a full Wheatstone piezoresistive bridge (12) in separate conditioning paths. Each path is provided with a bridge supply voltage (VHB1, VHB2) which can serve as a temperature related input signal to respective offset and gain compensation control circuits. The half bridge outputs are inputted to respective amplifiers (U1, U2) along with a selected percentage of the temperature dependent bridge supply voltage. The outputs of the amplifiers provide a signal proportional to respective half bridge output voltage. In one embodiment, the output of the amplifier (U2) in one conditioning path of one half bridge is connected to the input of an amplifier (U4) in the other conditioning path to provide a signal in the one path proportional to the Wheatstone bridge differential output voltage and in the other path a signal proportional to the Wheatstone half bridge output voltage.
    Type: Application
    Filed: October 22, 2002
    Publication date: April 22, 2004
    Inventors: David L. Corkum, Keith W. Kawate, Thomas R. Maher
  • Patent number: 6693445
    Abstract: A probe is disclosed which is suitable for use with an apparatus for monitoring the corrosion of a material by accurately measuring changes in the resistance of an exposed element (101) in relation to a reference element (103). The two elements are electrically connected in series via a bridge (131). The elements are formed from the same piece of material divided along an elongate slot (167) and are proximate to one another so that the temperature difference between them is kept to a minimum. This prevents false indications of corrosion by ensuring that the temperature coefficient of the resistivities is the same in both elements. The reference element (103) is covered with a corrosion-resistant layer. (113). This layer (113) is preferably as thin as possible and also a good thermal conductor to further ensure equal temperature of the reference (103) and exposed (101) elements.
    Type: Grant
    Filed: December 10, 2001
    Date of Patent: February 17, 2004
    Inventor: John Sutton
  • Patent number: 6683464
    Abstract: A stabilized fluid conductivity measurement system includes a threaded metal housing with an inner portion having two probes for contacting the fluid to be measured and having an outer portion in which electrical circuitry is mounted. The circuitry includes a balanced square wave generator providing excitation to a modified Wheatstone bridge, including first and second input excitation terminals, and first and second output terminals. Fixed resistances may be located in 3 arms of the Wheatstone bridge, and the fourth arm may have two resistances with an intermediate tap; and one of the two probes is connected to this tap while the other probe is connected to one of the input excitation points.
    Type: Grant
    Filed: March 1, 2002
    Date of Patent: January 27, 2004
    Assignee: Kavlico Corporation
    Inventors: Kyong M. Park, Tony Tuong Nguyen
  • Publication number: 20030173984
    Abstract: A current comparator technique is applied to four-terminal resistance measurements for obtaining a highly accurate AC resistance bridge at power frequencies of 50 Hz to 60 Hz. Active circuits are used to establish equal voltage drops between the potential terminals of the two resistances being compared. The bridge is suitable for measuring resistances from 10 &mgr;&OHgr; to 100 k&mgr;&OHgr;. A cascading technique using two two-stage current transformers provides extension of the ratio range to 100,00,000 with a maximum applied current of 10,000A. The bridge features measurement with a resolution of 0.1×10−6. The total combined uncertainty (2&sgr;) of the bridge including the range extenders, at power frequencies, is estimated to be less than 5 &mgr;&OHgr;/&OHgr;.
    Type: Application
    Filed: March 14, 2002
    Publication date: September 18, 2003
    Inventor: Eddy So
  • Patent number: 6608492
    Abstract: The output of a preamplifier is communicated to an active feedback circuit which drives the primary of a balancing transformer the secondary of which is connected in series with an impedance under test (IUT), the terminals of the series connection are communicated to respective differential inputs of the preamplifier. The feedback circuit automatically drives the preamplifier input toward balance, balance being achieved when the signal across the secondary equals the signal across the IUT in magnitude but opposite in phase. A DC blocking circuit is interposed between the series connection and the preamplifier for blocking preamplifier bias current from loading and heating the IUT. At balance an active equalizing transfer function circuit nulls any potential across the blocking circuit.
    Type: Grant
    Filed: August 20, 2001
    Date of Patent: August 19, 2003
    Inventor: Richard Carl Entenmann
  • Patent number: 6489787
    Abstract: A circuit capable of detecting natural gas at a wide range of concentrations is disclosed. The gas detection circuit includes a catalytic Wheatstone bridge circuit and an analyzing Wheatstone bridge circuit. A circuit for detecting natural gas, which includes placing a device containing the circuit described above in an area in which the air has a potential of containing natural gas, and monitoring the output signal for indications of the presence of natural gas is also disclosed.
    Type: Grant
    Filed: October 13, 2000
    Date of Patent: December 3, 2002
    Assignee: Bacharach, Inc.
    Inventor: Edward F. McFadden
  • Patent number: 6486679
    Abstract: A radio frequency bridge, useful for measuring complex values of an unknown impedance or associated complex reflection coefficient and VSWR value, which comprises an rf source, a novel asymmetrical bridge, a measuring device (comprising two logarithmic amplifiers, a difference amplifier and a phase detector), a computing device and a display or interface device. The complex impedance may be any two terminals of a general N-port network not to exclude an antenna with or without feed-line. The invention is more accurate than prior art when measuring complex impedance values having magnitudes from approximately five ohms to an upper value limited only by the dynamic range of the logarithmic amplifiers, normally greater than 4000 ohms. It has the great advantage of maintaining constant measuring accuracy over a wide measuring range and can be designed to operate over very wide bandwidths.
    Type: Grant
    Filed: January 21, 2002
    Date of Patent: November 26, 2002
    Inventor: Kenneth David Holt
  • Patent number: 6452405
    Abstract: Disclosed is a current sensing system for measuring the current flowing through a current sensing resistance. The system has a calibration resistance coupled to the current sensing resistance and a pair of input resistances each having a first end coupled to one of the ends of the current sensing resistance and a second end coupled to one of the ends of the calibration resistance. A voltage is created across the calibration resistance and the calibration resistance is set at a predetermined level to compensate for the current sensing resistance deviating from a reference value. The voltage is filtered and amplified to produce an output representative of the measured current.
    Type: Grant
    Filed: September 18, 2000
    Date of Patent: September 17, 2002
    Assignee: Delphi Technologies, Inc.
    Inventor: Steven James Collier-Hallman
  • Patent number: 6449966
    Abstract: An electronic control for the operation of a beverage dispenser of the refrigerated ice bank type is shown. The control provides for reliable determinations of when ice production is needed and when it is not needed. A microprocessor receives information from an ice bank probe and from a temperature probe located within the ice bank. Data collected by the microprocessor from both the ice bank probe and the temperature probe is used to determine if the ice bank is either insufficient in size and should be increased or is of sufficient size such that the compressor can be turned off. A carbonator level probe is also shown and connected to the microprocessor.
    Type: Grant
    Filed: October 28, 1997
    Date of Patent: September 17, 2002
    Assignee: IMI Cornelius Inc.
    Inventors: Timothy W. Bethuy, Douglas P. Goulet
  • Patent number: 6433554
    Abstract: An in-range fault detection system for a full wheatstone bridge element (12) having piezoresistive elements (R1, R2, R3, R4) has bridge outputs (INP, INM) connected to measuring means in the form of a first circuit portion (13) to provide a common mode voltage (VCM). A second circuit portion (14) is used to provide a centering voltage (C*VBRG) equal to the common mode voltage at the time of sensor calibration and a third circuit portion (15) is used to provide a small window voltage (W*VBRG) which is a fraction of bridge voltage. The value (W*VBRG) is subtracted from (C*VBRG) at a first summing circuit (SUM1) and added to (C*VBRG) at a second summing circuit (SUM2) and the results are each compared to the common mode voltage by comparators (Q1, Q2) which are then determined to be within or without a window of valid values by an OR gate (Q3).
    Type: Grant
    Filed: December 20, 1999
    Date of Patent: August 13, 2002
    Assignee: Texas Instruments Incorporated
    Inventors: Keith W. Kawate, David L. Corkum, Thomas R. Maher
  • Patent number: 6405578
    Abstract: A magnetic oxygen analyzer which employes a detector comprising a magnetic pole, heat generator arranged in a non-uniform magnetic field where the intensity of a magnetic field produced by the magnetic pole varies, and a magnetic wind sensor disposed to not be affected by heat produced by the heat generator. A change in electrical resistance of the sensor, caused by change in magnetic wind strength, is detected as the oxygen concentration of a mixed gas. The magnetic wind is caused by the magnetic field produced by the magnetic pole and by heat produced by the heater and is related to the oxygen concentration of the mixed gas exposed to the analyzer. Advantageously, the analyzer of the invention provides improved signal to noise ratio, is immune to ambient temperature, and eliminates the need for precise temperature control.
    Type: Grant
    Filed: May 22, 2001
    Date of Patent: June 18, 2002
    Assignee: Yokogawa Electric Corporation
    Inventors: Ryuuji Chiba, Hideaki Yamagishi, Masayuki Sato
  • Publication number: 20020066312
    Abstract: A position sensor and a method for sensing a position of a moveable member includes at least first and second deflectable members arranged so as to allow the moveable member to pass therebetween and cause the at least first and second moveable members to deflect in proportion to the position of the moveable member relative to the first and second deflectable members. In one example of the present invention, the deflectable members are cantilever-mounted members extending in generally the same direction. The amount of resultant deflection is measured by any suitable means. For example, each deflectable member may have a Wheatstone bridge provided thereon acting as a strain gauge in a known manner, such that the strain detected is proportional to the amount of deflection. In a particular example of the present invention, some of the elements of a first Wheatstone bridge are provided on the first deflectable member and some are provided on the second deflectable member.
    Type: Application
    Filed: December 1, 2000
    Publication date: June 6, 2002
    Inventors: Ivan P. Lebrun, David H. Ohnesorge
  • Publication number: 20020047716
    Abstract: Detection of excessive negative offset of a condition responsive sensor such as a pressure responsive full Wheatstone bridge element (10) and circuitry associated therewith is obtained by taking the sensor's output signal, preferably after the signal has been compensated for both gain and offset and comparing (Q1) the signal (Vx) with a reference voltage (VREF1) selected to reflect an unobtainable stimulus input condition and driving the compensated signal to a fault level when the compensated signal exceeds the reference voltage.
    Type: Application
    Filed: September 6, 2001
    Publication date: April 25, 2002
    Inventors: Thomas R. Maher, David L. Corkum
  • Patent number: 6329825
    Abstract: A pressure detecting bridge circuit produces a sensor signal Sd. A temperature detecting bridge circuit produces a temperature signal St. A reference voltage generating circuit produces a reference signal Sa. An analog multiplexer processes these signals Sd, St and Sa in a time-divisional manner. A differential amplification circuit and an A/D conversion circuit are commonly used to obtain the digital data corresponding to the sensor signal Sd, the temperature signal St and the reference signal Sa. The temperature detecting bridge circuit includes reference resistance elements. By adjusting the design resistance values of the reference resistance elements, the variation width of the sensor signal Sd in a pressure measuring range of the pressure detecting bridge circuit is substantially equalized in advance with the variation width of the temperature signal St in a temperature measuring range of the temperature detecting bridge circuit.
    Type: Grant
    Filed: November 16, 1999
    Date of Patent: December 11, 2001
    Assignee: Denso Corporation
    Inventors: Hiroaki Tanaka, Inao Toyoda
  • Patent number: 6118278
    Abstract: According to the invention, an AC-signal is superimposed to a signal on the two lines to be monitored. A signal difference between the signals on each line is compared with the superimposed AC-signal. A short circuit between the two lines to be monitored can thus be detected when the superimposed AC-signal is not present in the signal difference. The frequency of the AC-signal is preferably selected as half of the sampling frequency of a subsequent sampling means. In a measuring bridge, the short circuit detection unit is coupled to a first and a second measuring point of the bridge.
    Type: Grant
    Filed: August 18, 1998
    Date of Patent: September 12, 2000
    Assignee: Hewlett-Packard Company
    Inventor: Peter Rother
  • Patent number: 6040779
    Abstract: Monitoring of the function of a symmetrical sensor bridge circuit is performed in that the signal from the positive or negative half-bridge is subtracted from half the bridge supply voltage (V.sub.s /2) in a summing member (2) and is subsequently amplified by an amplifier (3) in such a way that it corresponds to the full bridge signal (V.sub.in). The full bridge signal (V.sub.in) is compared with the amplified difference signal in a comparator (5). If the difference signal deviates in an unacceptable manner from the full bridge signal, the comparator switches an alarm signal on the output signal (6) of the sensor, so that this output signal is placed into a range which lies outside of the normal operational range of the sensor.
    Type: Grant
    Filed: February 24, 1999
    Date of Patent: March 21, 2000
    Assignee: Robert Bosch GmbH
    Inventors: Georg Pfaff, Herbert Keller
  • Patent number: 5948978
    Abstract: Sensors for measuring the flow rate of a fluid and for monitoring heat transfer. An induction-heated temperature-responsive sensor in contact with and cooled by the fluid, changes temperature in proportion to the quantity of heat removed by the fluid thereby providing a basis for determining flow rate or heat transfer. A flow modulation method and apparatus for improving the precision of flow rate measurement is also presented.
    Type: Grant
    Filed: July 14, 1998
    Date of Patent: September 7, 1999
    Inventor: Murray F. Feller
  • Patent number: 5804703
    Abstract: A circuit for a combustible gas sensor comprising: a bridge circuit having first and second legs; a first node at a first midpoint in the first leg of the bridge circuit; a second node at a second midpoint in the second leg of the bridge circuit; a first temperature responsive resistive sensor element coupled between the first node and a bottom of the bridge circuit and located in a flow of combustible gas; a second temperature responsive resistive sensor element coupled between the bottom of the bridge and ground and located in the flow of combustible gas; and a voltage control circuit coupled to the first and second nodes and to the top of the bridge circuit for maintaining closed loop control of first and second node voltages at the first and second nodes by varying a bridge voltage at the top of the bridge circuit wherein one of the first and second sensor elements includes a catalyst for stimulating reactions of reactive constituents in the flow of combustible gas.
    Type: Grant
    Filed: June 9, 1997
    Date of Patent: September 8, 1998
    Assignee: General Motors Corporation
    Inventors: Robert Harold Wind, Paul Charles Spagnuolo
  • Patent number: 5804978
    Abstract: The circuit for feeding a Wheatstone Bridge (DMS 1 . . . DMS 4) with a rectangular waveform alternating voltage which is derived from a single DC reference voltage, consists of a first operational amplifier (V 1) whose positive input is connected to the DC reference voltage and whose negative input is connected via the switches (S 5 and S 6) alternately to the one (A) or to the other (B) feed point of the bridge, and a second operational amplifier (V 2) whose positive input is connected to ground potential and whose negative input is connected to one measuring input (C) of the bridge. The outputs of the two operational amplifiers (V 1 and V 2) are connected via the switches (S 1 . . . S 4) alternately to the one (A) and to the other (B) feed point of the bridge, and the output signal is taken off at the second measuring output (D) of the bridge.
    Type: Grant
    Filed: March 22, 1996
    Date of Patent: September 8, 1998
    Inventors: Joachim Scheerer, Hartmut Gruetzediek
  • Patent number: 5764067
    Abstract: The present invention, generally speaking, provides for highly accurate correction of a sensor output using circuitry that is compact and inexpensive. In accordance with one embodiment of the invention, an output signal of a sensor having a sensitivity that varies as a function of temperature and that includes resistors connected to form a bridge is corrected by, first, modeling the sensitivity of the sensor using an expression that is the ratio of two polynomials; applying a voltage across the bridge; and controlling the applied voltage as a function of temperature substantially in accordance with the inverse expression.
    Type: Grant
    Filed: May 10, 1995
    Date of Patent: June 9, 1998
    Inventor: Ali J. Rastegar
  • Patent number: 5734269
    Abstract: A bridge circuit monitoring apparatus which can accurately detect a fault in a bridge circuit of a sensor circuit even when multiple faults occur. Changes in the imbalance output signal of a bridge circuit (11) are monitored with a first window comparator (WC1), while changes in the bridge circuit (11) power source current, which does not require amplifying, are monitored with a second window comparator (WC2). At the time of an output of logic value "1" indicating that the monitoring outputs are both normal, an output of logic value "1" indicating that the bridge circuit (11) is normal is generated from an AND gate (13).
    Type: Grant
    Filed: April 5, 1996
    Date of Patent: March 31, 1998
    Assignee: The Nippon Signal Co., Ltd.
    Inventors: Masayoshi Sakai, Toshihito Shirai, Hiroji Anzai, Koichi Futsuhara
  • Patent number: 5656938
    Abstract: For determining the air mass flow in the intake pipe of an internal combustion engine by means of an electrical bridge, normally the current flowing through the current measurement resistor when balancing the bridge is evaluated as an indirect measure of the air mass flow. The primary measured quantity for the air mass flow is, however, the power converted at the air flow measurement resistor around which the air flows so that the indirect measurement always includes an error. To reduce this measurement error, the invention utilizes the evaluation of the sum of the voltage across the current measurement resistor and the voltage or a partial-voltage across the air flow measurement resistor as a measure of the air flow.
    Type: Grant
    Filed: January 26, 1995
    Date of Patent: August 12, 1997
    Assignee: DAUG Deutsche Automobilgesellschaft mbH
    Inventors: Thomas Bennohr, Michael Daetz
  • Patent number: 5619144
    Abstract: Detector and method for detecting the presence of a liquid, such as water dew or of ice, or for detecting a change of phase in liquid, based on a change in an electrical resistance. The detector comprises a substrate onto whose face one or several resistor patterns are applied. For detecting the presence of a liquid or ice or equivalent by a change in the detector resistance, a low-mass detector resistor pattern is applied onto a substrate out of such a metal or equivalent as has a considerable dependence on temperature. On the substrate, there are contact patterns that feed a short pulse of electric current to heat the detector resistor as a short pulse, the presence of a liquid or ice and or a change of phase being detected by the change in resistance taking place during the short pulse. The thickness of the metal film in the resistor pattern (15) of the detector resistor (R.sub.det) is, as a rule, chosen as s<1 .mu.m.
    Type: Grant
    Filed: August 23, 1994
    Date of Patent: April 8, 1997
    Assignee: Vaisala Oy
    Inventor: Lars Stormbom
  • Patent number: 5583442
    Abstract: A differential voltage monitor is shown using a resistive bridge to produce a sample value representing that differential voltage. A portion of the resistive bridge is located on an IC and a portion is external to the IC. The object is to compare the differential voltage with a reference, producing a logic signal at a threshold level. The threshold level serving as a reference and the sample valve representing the differential voltage are made to be equally dependent on the bridge components located on the IC. In this way, any changes in the IC located bridge resistors compared to the bridge resistors located outside the IC are prevented from affecting the measurement.
    Type: Grant
    Filed: February 3, 1994
    Date of Patent: December 10, 1996
    Assignee: Harris Corporation
    Inventors: Robert H. Isham, Stanley F. Wietecha
  • Patent number: 5543633
    Abstract: A method for measuring the degree of planarity in an integrated circuit includes depositing, onto a dielectric layer to be measured for planarity, a predetermined measure path of a conductive film and measuring the electric resistance of said measure path. The resistance of such a measure path is minimal where the surface on which it has been deposited is perfectly planar, and increases with the surface deviation from perfect planarity. An integrated circuit containing a measurement portion of conductive film and a reference portion of conductive film is described.
    Type: Grant
    Filed: July 15, 1993
    Date of Patent: August 6, 1996
    Assignee: SGS-Thomson Microelectronics S.r.l.
    Inventors: Aldo Losavio, Giuseppe Crisenza, Giorgio De Santi
  • Patent number: 5532582
    Abstract: An analog input apparatus comprises bridge measuring devices 11 and 31 connected to a bipolar voltage power supply 5, analog multiplexers 18, 19, 38, and 39 responsive to an output level of an oscillator 4B for switching a polarity and outputting two outputs of each of the bridge measuring devices 11 and 31, amplifiers 12 and 32 for amplifying bipolar outputs provided through the analog multiplexers 18, 19, 38, and 39, and an analog-to-digital converter 2 for converting outputs of the amplifiers 12 and 32 into digital form and outputting the resultant digital values.
    Type: Grant
    Filed: September 8, 1994
    Date of Patent: July 2, 1996
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Noritaka Egami
  • Patent number: 5521492
    Abstract: An analog input method comprises the steps of correcting a measured value with the digital value output when voltage at either middle point of a bridge circuit is fed into both input terminals of a differential analog amplifier or feeding two middle-point voltages of a bridge circuit into input terminal of an analog amplifier in order and providing a measured value based on the difference between the digital values output from the analog amplifier.
    Type: Grant
    Filed: September 8, 1994
    Date of Patent: May 28, 1996
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Noritaka Egami
  • Patent number: 5485100
    Abstract: The output of a bridge measurement circuit is sampled at a time when there is no desired, or expected, bridge output signal, and a balance voltage applied to the bridge measurement circuit is automatically adjusted such that the sample bridge output signal is equivalent to a reference output signal. After the bridge is balanced, the balance voltage is automatically modified by a calibration voltage calculated to provide a known change in the sample bridge output signal, and the sample bridge output signal is compared to a reference output to automatically check the bridge measurement circuit gain. The balance voltage may be automatically modified by multiple calibration voltages, and the sample bridge output signal provides an indication of the linearity of the amplifier gain. The sample bridge output signal is monitored after a change in the balance voltage to automatically provide an indication of the bridge measurement circuit filter cutoff frequency.
    Type: Grant
    Filed: June 4, 1993
    Date of Patent: January 16, 1996
    Assignee: United Technologies Corporation
    Inventor: James R. Kogut
  • Patent number: 5481199
    Abstract: A constant current loop measuring system measures a property including the temperature of a sensor responsive to an external condition being measured. The measuring system includes thermocouple conductors connected to the sensor, sensing first and second induced voltages responsive to the external condition. In addition, the measuring system includes a current generator and reversor generating a constant current, and supplying the constant current to the thermocouple conductors in forward and reverse directions generating first and second measured voltages, and a determining unit receiving the first and second measured voltages from the current generator and reversor, and determining the temperature of the sensor responsive to the first and second measured voltages.
    Type: Grant
    Filed: September 24, 1993
    Date of Patent: January 2, 1996
    Inventors: Karl F. Anderson, Allen R. Parker
  • Patent number: 5461322
    Abstract: A feedback operated DC bridge circuit for monitoring the voltage variations in a voltage divider circuit using a voltage controlled resistance component to reach a null balance across the bridge. Amplification is provided at higher accuracy near the null point when the voltage difference across the bridge is zero. The feedback bridge circuit includes an integrator which directly drives the controlling component to the value of the resistance in an unknown branch to force the null condition. The voltage controlled component (configured as a discrete metal oxide semiconductor device or bipolar junction transistor) and the balancing scheme are suitable for microfabrication and provides noise-rejection enhancement. The interconnected integral feedback of the autonulling DC bridge enables both a neural network for pre-processing sensor input in a spatial domain as well as general analog computation that mimics a first order differential equation in the form of the system state equation.
    Type: Grant
    Filed: August 6, 1993
    Date of Patent: October 24, 1995
    Assignees: Geo-Centers, Inc., Naval Research Laboratory
    Inventors: Paul P. Bey, Jr., Thomas L. Fare, David J. Yonce
  • Patent number: 5440234
    Abstract: A semiconductor sensor has piezo resistor elements formed in deformable semiconductor portions for forming a Wheatstone bridge circuit, and a fault detecting circuit is associated with the Wheatstone bridge circuit for producing a warning signal indicative of occurrence of a fault in the Wheatstone bridge circuit, wherein the fault detecting circuit has two pairs of window comparators independently monitoring two output nodes of the Wheatstone bridge circuit to see whether or not the voltage level at each of the output nodes ranges between the upper limit and the lower limit of a normal voltage range so that a destruction of one of the piezo resistor elements is detectable.
    Type: Grant
    Filed: October 7, 1993
    Date of Patent: August 8, 1995
    Assignee: NEC Corporation
    Inventor: Yuji Kondo
  • Patent number: 5419190
    Abstract: A method and apparatus for measuring mass flow rates and other characteristics of a fluid in a large conduit uses a sensor circuit having a heater/thermometer, a reference resistor, and a thermometer resistor arranged in four-wire network to enable measurement of all characteristics of the resistor network. That sensor circuit is preferably mounted on an interior wall surface of a support tube. A plurality of such support tubes, each having a plurality of sensors within the support tube, are mounted in an array in the cross section of the duct. A cleaning plate for cleaning the exterior surface of the support tube permits calibration of the network while cleaning. A program for using the circuit to calculate values of interest and to display desirable output data is also disclosed, as is a program for controlling the cleaning/calibration cycle.
    Type: Grant
    Filed: August 3, 1992
    Date of Patent: May 30, 1995
    Assignee: Thermal Instrument Co.
    Inventor: Branin A. Boyd
  • Patent number: 5400668
    Abstract: A superconducting magnet includes a superconducting coil, an inner tank for containing the coil, a shield plate for covering the inner tank, and an outer tank for accommodating the superconducting coil, the inner tank and the shield plate. The inner tank is supported on the outer tank by a load support member and the outer tank forms a vacuum vessel. At least one of the inner tank, the load support member, the shield plate and the outer tank includes a detection arrangement for detecting abnormality and/or deterioration of the inner tank, load support member, shield plate and outer tank associated with the respective detection arrangement.
    Type: Grant
    Filed: December 23, 1992
    Date of Patent: March 28, 1995
    Assignee: Hitachi, Ltd.
    Inventors: Toshio Hattori, Hiroshi Aoyama, Saburo Usami, Toshio Ishizuki, Tosuke Hirata, Shigeru Sakamoto, Yumiko Seki, Tadasi Sonobe, Fumio Suzuki, Sueo Kawai
  • Patent number: 5371469
    Abstract: A constant current loop measuring system is provided for measuring a characteristic of an environment. The system comprises a first impedance positionable in the environment, a second impedance coupled in series with said first impedance and a parasitic impedance electrically coupled to the first and second impedances. A current generating device, electrically coupled in series with the first and second impedances, provides a constant current through the first and second impedances to produce first and second voltages across the first and second impedances, respectively, and a parasitic voltage across the parasitic impedance. A high impedance voltage measuring device measures a voltage difference between the first and second voltages independent of the parasitic voltage to produce a characteristic voltage representative of the characteristic of the environment.
    Type: Grant
    Filed: February 16, 1993
    Date of Patent: December 6, 1994
    Assignee: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
    Inventor: Karl F. Anderson
  • Patent number: 5357189
    Abstract: An analog input apparatus comprises bridge measuring devices 11 and 31 connected to a bipolar voltage power supply 5, analog multiplexers 18, 19, 38, and 39 responsive to an output level of an oscillator 4B for switching a polarity and outputting two outputs of each of the bridge measuring devices 11 and 31, amplifiers 12 and 32 for amplifying bipolar outputs provided through the analog multiplexers 18, 19, 38, and 39, and an analog-to-digital converter 2 for converting outputs of the amplifiers 12 and 32 into digital form and outputting the resultant digital values.
    Type: Grant
    Filed: October 6, 1992
    Date of Patent: October 18, 1994
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Noritaka Egami
  • Patent number: 5345184
    Abstract: A humidity detection circuit includes a bridge circuit containing temperature sensing elements. The bridge circuit is connected in series to a current limiting resistance, a current controlling element and a power supply. There is a set of resistances arranged in parallel with the current limiting resistor and the bridge circuit. A voltage comparing circuit is operatively connected to the bridge circuit the current limiting resistance and the set of resistances. A control section is provided to detect the potential of a junction between the bridge circuit and the current limiting resistance. Based upon the detector potential, the humidity detection circuit changes resistance value of a resistor in the set to an optimal level so that temperature drift does not occur.
    Type: Grant
    Filed: December 14, 1992
    Date of Patent: September 6, 1994
    Assignee: Sharp Kabushiki Kaisha
    Inventor: Yuuzi Andoh
  • Patent number: 5287065
    Abstract: Automatic bridge balancing apparatus includes a reference impedance and a measuring terminal pair for receiving an unknown impedance. A source of a test signal is coupled to the reference impedance and the measuring terminal pair. A measuring detector is connected in series with the unknown impedance when connected to the measuring terminal pair to provide a measured signal. A reference detector is coupled to the reference impedance to provide a reference signal. A combiner combines the measured signal with the reference signal to provide an error signal. The reference detector includes an up/down counter coupled to a digital attenuator that provides the reference signal. A controller responds to the error signal to control the count in the up/down counter so that the associated digital attenuator provides a signal to the combiner that reduces the error signal so that the count in the up/down counter is characteristic of the unknown impedance.
    Type: Grant
    Filed: October 4, 1991
    Date of Patent: February 15, 1994
    Assignee: Doble Engineering Company
    Inventor: Lars P. Allfather
  • Patent number: 5279145
    Abstract: A heater control device for an air-fuel ratio sensor which comprises: an air-fuel ratio sensor comprising a sensor element which detects an air-fuel ratio state of exhaust gas of an engine, and a heater which heats the sensor elements; a heater current flow control means for controlling a value of a resistance of the heater to be a target resistance value; a harness having a couple of couplers at both ends thereof which connects between the air-fuel ratio sensor and the heater current flow control means; and a current detecting resistance which is incorporated in the coupler on the air-fuel ratio sensor side, or provided adjacent to said coupler on the air-fuel ratio sensor side, and which is connected to the heater in series and detects current of the heater.
    Type: Grant
    Filed: October 23, 1992
    Date of Patent: January 18, 1994
    Assignee: Mitsubishi Denki K.K.
    Inventor: Hiroyoshi Suzuki
  • Patent number: 5272445
    Abstract: A portable resistance tester comprises a pair of regulator circuits used to drive a bridge circuit and a detector circuit when measuring the resistance values of "in-circuit" test nodes. The tester produces an audible signal when the resistance of a measured test node falls within, or without, a predetermined resistance range.
    Type: Grant
    Filed: July 1, 1992
    Date of Patent: December 21, 1993
    Assignee: Digital Equipment Corp.
    Inventors: Steven G. Lloyd, Hamid Partovi
  • Patent number: 5233308
    Abstract: A thermal conductivity cell in the form of a bridge is used as one of the resistors in a Wheatstone bridge network. The output of the thermal conductivity cell is applied to the input of a low noise amplifier, the output of which is differentiated by an R-C coupling network having a time constant selected to pass a substantial portion of the output signal from the thermal conductivity cell with minimum attentuation. The R-C differentiating coupling network effectively reduces DC errors due to drift and offset and shapes the output signal improving the signal-to-noise ratio enabling trace amounts of materials to be analyzed.
    Type: Grant
    Filed: March 6, 1992
    Date of Patent: August 3, 1993
    Assignee: Leco Corporation
    Inventor: Peter M. Willis
  • Patent number: 5231374
    Abstract: A slip ring includes a rotor and a stator. Stator contacts are connected to a data acquisition unit. The rotor contacts are connected to an amplifier circuit mounted in a housing connected to and rotatable with a rotating member. A sensor mounted on the rotating member to which the rotor is also fixedly mounted generates an electrical output signal corresponding to a sensed operating parameter of the rotating member. The sensor output signal is amplified by the amplifier in the housing before being transmitted through the slip ring to the data acquisition unit. Vibration isolation is provided when required for the slip ring and the circuit board in the housing carrying the amplifier to dampen vibrations generated by the rotating member. Resilient pads are mounted on the circuit board and engage the housing attached to the rotor.
    Type: Grant
    Filed: September 23, 1991
    Date of Patent: July 27, 1993
    Assignee: Michigan Scientific Corporation
    Inventors: Hugh W. Larsen, Ralph W. Larsen, David A. Hoffer
  • Patent number: 5225786
    Abstract: A combustible gas sensor includes a housing defining an interior containing a reference bead and a measurement bead which are fully exposed by the removal of the shroud or can therefrom. The beads are electrically connected in series and the reference bead is connected in parallel with a resister to define one side of a Wheatstone bridge. A liner consisting of a disk defining an inner face and an outer face overlies the reference and measurement beads. The inner face of the disk is provided with a slot opening at the inner face which is dimensioned to receive the reference and measurement beads therein. The slot provides a confined space for fluid communication between the fully exposed beads. A through running opening is disposed in the disk on each side of the slot adjacent the end of the slot in which the reference bead is disposed. A channel extends from each of the openings and communicates with the slot.
    Type: Grant
    Filed: October 25, 1991
    Date of Patent: July 6, 1993
    Assignee: Rosemount Analytical, Inc.
    Inventors: Eldon D. Vaughn, Samuel C. Creason
  • Patent number: 5189362
    Abstract: A circuit for measuring the R.M.S. voltage of a high frequency signal (e.g. 100MHz) comprises two series-connected ntc thermistors (TH1, TH2) in a bridge circuit which is energized by a current source (1). The unknown signal is applied across one (TH1) of the thermistors and the resulting change in the resistance causes a D.C. output voltage to appear across the balanced terminals (T3, T4) of the bridge. This output voltage is proportional to the square of the R.M.S. voltage of the A.C. signal. In another embodiment, two ptc thermistors are connected in parallel in a bridge circuit which is energized by a voltage source, and are used to measure R.M.S. current. In each case, the thermistors are preferably operated in a negative slope resistance portion of their voltage-current characteristic.
    Type: Grant
    Filed: January 3, 1991
    Date of Patent: February 23, 1993
    Inventor: Richard G. V. Doble
  • Patent number: 5159277
    Abstract: A precision bridge measurement circuit connected to a current source providing a linear output voltage versus resistance change of a variable resistance (resistance temperature transducer) including a voltage follower in one branch of the bridge so that the zero setting of the transducer resistance does not depend upon the current source or upon an excitation voltage. The zero setting depends only on the precision and stability of the three resistances. By connecting the output of an instrumentation amplifier to a feedback resistor and then to the output of the voltage follower, minor nonlinearities in the resistance-vs-temperature output of a resistance-temperature transducer, such as a platinum temperature sensor, may be corrected. Sensors which have nonlinearity opposite in polarity to platinum, such as nickel-iron sensors, may be linearized by inserting an inverting amplifier into the feedback loop.
    Type: Grant
    Filed: October 24, 1990
    Date of Patent: October 27, 1992
    Assignee: The Perkin Elmer Corporation
    Inventor: Bruce E. Mount