Abstract: A miniature, solid state, cantilever beam accelerometer is constructed with an arrangement of strain sensing elements which provides for simpler temperature compensation, dual-axis acceleration measurement, and the capability of correcting for nonlinearity in a strain sensing element. Temperature compensation is facilitated by locating two strain sensing elements on the cantilever beam and two on the main body of the accelerometer and connecting the four elements in a Wheatstone bridge. Instead of a single bridge, two half bridges may be formed to allow for independent adjustment of each side of the Wheatstone bridge. Independent adjustment is also possible by using two full bridges with all strain sensing elements oriented in the same direction. If the elements of one bridge are oriented in an orthogonal direction, the accelerometer is capable of measuring both on-axis and off-axis accelerations.

Abstract: A strain sensor includes an insulating resin, e.g. polyimide resin, film formed on a beam body having a strain generating section and a wiring layer having a resistance material, e.g. nickel-chrome, layer formed on the polyimide resin film and a gold layer selectively formed on the nickel-chrome layer. A solid powder, e.g. silicon dioxide, is mixed with the polyimide resin film.

Abstract: A temperature compensation circuit for strain gauges fixed to an object to be measured and adapted to take out an output conforming to a strain by being fed with a constant voltage, wherein a compensation resistors in the form of a combination of two or more kinds of resistors each made of a pure single metal material having a resistance versus temperature characteristic equivalent to the output voltage versus temperature characteristic of the bridge circuit of strain gauges are inserted and connected at a predetermined position on the voltage supply side or output take-out side of the bridge circuit of strain gauges thereby compensating for variations in the strain gauge output due to temperature variations with high accuracy. The temperature compensation circuit for strain gauges according to the present invention not only has very high accuracy of temperature compensation but also can be produced with high yield.

Abstract: A temperature compensated measuring system for measuring linear deformation due to the application of force. Electrical signals produced by a pair of dissimilar metal thermal detectors utilizing a pair of linear variable differential transformers are electrically summed to provide a signal free of thermal influence. Parallel rods of diverse metals are interconnected through one LVDT while a portion of one of the rods is connected to the member to be measured by the other LVDT and the summation of electrical signals permits an electrical thermally compensated readout indicating deformation due to force.

Abstract: A sensitive element is described for use with a strain sensor, which has low sensitivity to temperature.The sensitive element comprises a support, preferably consisting of a thin plate, on which is secured a piezoelectric resonator preferably shaped as a double tuning-fork. The deformations of the support are transmitted to the resonator thereby modifying the frequency of resonance.

Abstract: A resistance bridge circuit is temperature compensated, for both zero error and sensitivity, over a predetermined temperature range by connecting a first compensating resistance in series with one resistor of the bridge, and a second compensating resistance in parallel with the same or an adjacent resistor of the bridge, to reduce zero error, the positions and values of the first and second resistances being determined from measurements, at a plurality of temperature levels, of the voltage levels and resistance values of the bridge, and on the arrangement of proposed external connections to the bridge. Third and fourth compensating resistances are connected in series and parallel respectively with the bridge as a whole, the values of the third and fourth resistances being dependent on measurements as aforesaid and on the proposed external connections. The four compensating resistances are the only compensating elements required to provide a predetermined zero error and sensitivity.

Abstract: A hybrid transducer employing a ceramic substrate having on a surface a suitable geometry for defining an active or clamped area, a semiconductor strain gage is positioned on said substrate within said active area and connections are made to said gage by conductors printed on said substrate by thick or thin film techniques. Thick film printing techniques or thin film deposition techniques are employed to print the conductors, terminal areas, compensating resistors and stop members.

Abstract: A transducer operating on the strain gauge principle having integral temperature compensation and calibration resistors is disclosed. In the presently preferred embodiment, a silicon dioxide layer is disposed on a silicon substrate. Platinum alloy strain gauge resistors are disposed on the silicon dioxide layer and form a Wheatstone bridge circuit configuration. Laser trimable chromium nitride, platinum alloy and gold temperature compensation and calibration resistors are formed on the silicon dioxide layer from the same films used to form the strain gauge, adhesion layers, conductors and bonding pads, to permit the transducer to be calibrated such that its electrical characteristics are in conformance to specified tolerances when the transducer is subjected to temperature variations.

Abstract: A three-wire static strain gage apparatus utilizing a switching unit in combination with a Wheatstone bridge circuit to make strain gage measurements which are temperature corrected by switching to a temperature gage to measure the strain gage circuit's temperature at the time of the strain measurement.

Abstract: Compensating apparatus for a shear gage transducer employing a piezoresistor. The shear gage transducer or sensor is of a cross-shaped planar configuration where a lack of symmetry in structure or in fabrication undesirably provides offsets at the output terminals associated with the horizontal cross arm. The compensating apparatus includes a series chain of resistors positioned between selected terminals of said sensor to provide a desired null output voltage over a temperature operating range. Further embodiments depict a shear sensor having a unique contact configuration to enable resistive compensation of undesired offsets.

Abstract: A strain gauge comprises a tensoresistor sensitive element (1), a mechanical compensating element (10) and a spacer element (9) made of a material whose linear thermal expansion coefficient is substantially lower than the thermal expansion coefficient of the material of the mechanical element (10). The latter carries a heater element (15) and a thermoresistor element (16) intended for programmed straining of the mechanical element (10) in the course of the adjustment and calibration of the gauge. An electric circuit for adjusting and calibrating a strain gauge is a bridge circuit inserted into each of the two adjacent arms of which is a tensoresistor (3,4) of the sensitive element (1). Connected to a vertex (32) of a half-bridge circuit is the heater element (15), whereas to the other vertex (37) thereof is the thermoresistor element (16).

Abstract: A method and apparatus are described for using a computer to compensate for zero point and span errors as well as other non-linearities in the operation of strain gauge transducers. The apparatus comprises a semiconductor strain gauge transducer with a quasi stable voltage supply, two strain gauges and two precision resistors which form a voltage divider network; a scanner for scanning the strain gauges and precision resistors; an analog-to-digital converter for digitizing the output of the scanner; and a microprocessor for calculating a corrected output representing the phenomenon that is monitored by the strain gauge transducer. The microcomputer contains a memory in which are stored a set of bridge completion constants, a table of correction constants and a set of temperature compensation and signal conditioning algorithms.

Abstract: A capacitive transducer indicates the value of a physical quantity to be measured and is constructed with two spaced electrically conducting plates movable relative to one another in response to a mechanical signal representative of the physical quantity to be measured to generate an electrical signal in response thereto with the transducer capacitor being actuated and de-actuated to be respectively responsive and non-responsive to the mechanical signal in accordance with pre-designated time intervals. The electrical signal in accordance with the capacitance of the transducer capacitor is integrated to provide an output signal when the integrated signal exceeds a reference value.

Abstract: A load cell includes a bridge circuit having first to fourth strain gauge resistors and first and second temperature compensating resistors connected to the respective first and second strain gauge resistors. The first to fourth strain gauge resistors comprise a Nichrome layer formed on an insulating film, the first and second temperature compensating resistors each comprise a two-layered structure of the Nichrome layer and a titanium layer formed thereon, and connecting means for connecting the first to fourth strain gauge resistors and first and second temperature compensating resistors comprise a three-layered structure of the Nichrome layer and titanium layer and also a gold layer formed on the titanium layer.

Abstract: A Wheatstone bridge circuit for a strain gage designed to eliminate the zero offset due to heated cables occurring when the active elements of the bridge circuit are elevated to high temperatures. The bridge circuit comprises an active, a dummy and two completion resistors and is distinguished from conventional bridge circuits in that the resistance of the completion resistors substantially exceeds the value of any other resistors in the bridge circuit. The cables are used to connect the active and dummy resistors which are at the elevated temperatures to the completion resistors which are at room temperature. Heat induced resistance changes in the cables normally produce the zero offset because the cables form a part of the bridge circuit and are heated unevenly; however, the high value of completion resistors incorporated in the present invention tend to nullify the resistance changes in the cables and thereby eliminate the zero offset.

Abstract: There is disclosed an apparatus and a technique for shunt calibration of a Wheatstone bridge array independent of temperature. The structure involves a side completion half bridge array which has two temperature sensitive resistors as semiconductor strain gages forming one arm of the bridge and two temperature insensitive resistors forming the other arm of the bridge. An input voltage is applied to two opposite terminals of the bridge via equal span resistors and an output is taken between the common terminals of each of the bridge arms. A calibration resistor is positioned to shunt a span resistor and a temperature insensitive resistor to provide a calibrated output voltage of a magnitude independent of temperature.

Abstract: A pressure transmitter is provided for producing a voltage signal representative of the magnitude of pressure being applied to a diaphragm of the transmitter, wherein a network including strain-sensitive resistors that are formed in the diaphragm is coupled to the output of a constant-current power supply for producing the voltage signal in response to the strain generated by the applied pressure in the diaphragm and a feedback circuit operates in a non-linear manner for generating a control signal in response to a temperature signal produced by the network. The power supply coupled to receive the control signal is responsive thereto for changing the current supplied to the network so that compensation is thereby provided for errors in the pressure measurement caused by changes in the temperature of the network resistors.

Abstract: A strain measuring device using a Wheatstone bridge circuit. An excitation voltage changing switch switches from one excitation voltage to a different excitation voltage in accordance with a controlling circuit providing sequence operation of them and of other circuit elements to remove spurious components affecting the measurement of strain. Such spurious components include potential errors due to thermal electromotive force produced inside or outside said Wheatstone bridge circuit and sensitivity error due to drift voltage occurring in the driver circuit of the bridge current source. A comparator may be used to effect judgment of the amount of the measured value of the voltmeter, so that the controlling circuit causes excitation voltage changing switch to select only two excitation voltages out of at least three for switching no matter how many excitation voltages are provided for in the bridge current supply source.

Abstract: An abrasive wear tester wherein a segment of a relatively small diameter O-ring is held in contact with a rotating cylindrical disk. The disk is mounted to rotate about its longitudinal axes at a known rate for a specified period of time. The O-ring segment and cylinder are immersed in an abrasive fluid. The abrasive particles are pulled between the wear surfaces causing removal of the surface materials, predominantly the softer O-ring material. The O-ring specimen is cut from an O-ring and weighed prior to test. After the test the O-ring segment is again weighed and the weight of material removed by wear is calculated. These measurements indicate the wear resistance of the O-ring being tested. Service loads or pressures are simulated by means of a cable and weight system urging the O-ring against the cylindrical wear disk surface by means of a lever arm pulley arrangement or similar loading device.

Abstract: A capacitive pressure transducer 10 with an analog output voltage which varies linearly as a function of sensed pressure is provided. A capacitive pressure sensor C.sub.x provides a pressure variable capacitance that determines the frequency of a sensor oscillator 11. The oscillator frequency is combined with a reference frequency by a pair of D-type flip-flops 18 and 19 to provide a resultant signal having a duty cycle related to the sensed pressure. The resultant signal is integrated to provide a first analog signal as an input to a controllable gain amplifier 24 which receives gain control information from a non-linear gain control circuit 40 that receives an analog control signal as an input. The analog control signal varies as a function of sensed pressure in an opposite manner to said first analog signal. Said non-linear circuit provides for non-linearly varying the gain of amplifier 24 as a function of sensed pressure. Preferably the non-linear circuit 40 includes temperature compensating diodes 47.

Abstract: An improved pressure/temperature probe whose accuracy will not be affected by the pressures and temperatures to which it is subject or by the resistance of the connecting cables. The probe includes a separate pressure transducer and temperature transducer which are connected in series to a constant current source. In addition to the pressure reading taken by the pressure probe, a temperature reading of the pressure probe is derived from the pressure probe. This temperature reading provides the actual temperature of the pressure probe and permits highly accurate temperature correction. The pressure probe is constructed and arranged so as to have a high thermal time constant while the temperature probe is constructed and arranged to have a low thermal time constant.

Abstract: A measurement circuit and calibration technique for temperature compensating a half-bridge-high-temperature strain gage, capable of providing data which is independent of cable resistance variations.The need for a compensating resistor is eliminated and the cable conductors are removed from the measurement circuit. The output signal is easily and accurately converted to a measurement of strain without the need for auxiliary measurement required with prior art circuitry.

Abstract: A circuit for compensating the temperature dependence of the deformation properties of a pressure transducer sensor, having four basic parts: a current source having an output proportional to the sensor temperature, a constant voltage source, a Norton divider, and an operational amplifier. One brach of the Norton divider is a variable conductance ladder having an output current which increases at a programmed rate as the current from the temperature dependent source increases. The programmed rate is based on the temperature-dependent characteristic of the transducer sensor. The two branches of the Norton divider are connected as inputs to the operational amplifier. The operational amplifier provides the output of the compensating circuit, which is the difference between the reference voltage of the voltage source and the voltage at the output of the variable conductance ladder.

Abstract: An integrated circuit stress transducer system including signal processing circuitry responsive to signals from semiconductor stress sensors where the processing circuitry output signals are compensated for sensor stress sensitivity variations.

Abstract: A semiconductor pressure detector apparatus has a strain--electric signal conversion bridge which is composed of four semiconductor strain gauges, and an amplifier which serves to hold at a predetermined value the sum of currents flowing through the bridge. The midpoints of two arms constituting the bridge are respectively connected to the noninverting inputs of two negative feedback amplifiers. Outputs from the two negative feedback amplifiers are applied to a differential amplifier, and an output proportional to the difference of the outputs of the former amplifiers appears at an output terminal of the latter amplifier.

Abstract: A bridge circuit consisting of two or more resistance strain gauges is formed on a synthetic layer on which a resistance layer and a metal layer provided for the terminal elements are applied. The corresponding patterns are etched into the metal and into the resistance layer. Balance surfaces consisting of materials with a temperature coefficient different from that of the resistance layer are connected in series to the resistance strain gauges. By changing the resistance of the balance surfaces, the circuit is balanced in terms of symmetry, in terms of the temperature coefficient of the resistance layer, and in terms of the temperature coefficient of the modulus of elasticity of the test object.

Abstract: A thin film strain gage transducer includes temperature compensation resistances on an unstrained portion of the flexure element of the transducer. The compensation resistances are formed of the same material as the electrical leads interconnecting the strain gage resistances and also are deposited simultaneously with the electrical leads during manufacture.

Abstract: A compensation technique and network circuitry for a quad-diode demodulator and capacitive transducer combination is disclosed. The compensation method includes varying the amplitude of an alternating carrier frequency oppositely to the changes produced in that amplitude by the compensable errors in the demodulator and transducer. In one preferred embodiment ratiometric compensation and temperature compensation for the demodulator and any capacitive transducer is produced. In a second embodiment linearization and temperature compensation for the demodulator and a quartz capacitive transducer is provided.

Abstract: A strain-gage transducer incorporating a plurality of electrical-resistance strain gages coupled together in a bridge network is caused to remain zero-balanced under varying-temperature conditions by way of dual-resistance foil-type unit interposed at one of the output corners of the bridge with its two like foil-resistance elements occupying adjacent arms. The foil material is selected to exhibit a resistance change with temperature representing a factor which enables a target room-temperature measurement to be calculated once a rate of change of bridge output with temperature has been determined from measurements taken while the unstrained transducer is held at different temperatures. Relatively broad surfaces of the foil elements are left exposed, and the unit of which they are a part is so disposed in relation to the transducer structure that the exposed foil is accessible for controlled erasure-type abrasion which will bring about the target measurement and attendant compensation.

Abstract: A circuit including a strain gage bridge having a constant current supply at a constant temperature and otherwise variable with temperature. Linearization and accuracy are obtained through a feedback connection. The constant current and temperature compensation features and common mode rejection are also employed to improve accuracy.

Abstract: Strain gauge characteristic stabilization apparatus comprises a parallel connected combination of strain sensitive resistance (i.e., R.sub.eq), temperature conditioning means proximate R.sub.eq, and circuit means between R.sub.eq and the temperature conditioning means. The circuit means senses deviations in R.sub.eq from a predetermined value and causes the temperature conditioning means to control the temperature of R.sub.eq so as to reduce the deviations substantially to zero.

Abstract: A strain gage particularly suited for use in detecting and measuring mechanically induced strain in thermally strained specimens including an elongated link, adapted to be fixedly secured to the surface of a specimen, having thermal expansion characteristics matched with those of the specimen, and characterized by a differential capacitor employed for detecting strain induced motion as such motion is effected between the link and the surface of the specimen.

Abstract: A semiconductor sensor configuration employs piezoresistors arranged in a bridge configuration. A memory has stored therein at predetermined locations, values indicative of error voltages associated with the particular bridge circuit due to undesireable variations of temperature and pressure. The bridge circuit is coupled to digital processing circuitry which serves to access the memory at desired locations to retreive the values stored and to process these values in order to compensate the output signal supplied by the bridge during operation to provide a compensated output signal truly determinative of the applied pressure as being compensated for the particular error signals as stored in the memory.It is also understood that the above described technique has applicability in compensating other sensor configurations which employ non-semiconductor strain gages.

Abstract: Improved bridge circuits are described for offsetting span errors, for making scale adjustments and for providing for a non-linear output.

Abstract: A bridge circuit with four arms including semiconductor strain gauge elements has input terminals for coupling a DC power supply with a pair of diagonally opposite junctions of the bridge circuit per se and output terminals coupled with a pair of remaining diagonally opposite junctions. Initial zero-point temperature compensators each are connected in series and in parallel to each of semiconductor strain gauge elements on adjacent two arms of the bridge circuit. Temperature compensators for zero-point shift adjustment are each provided between the adjacent arms closer to each output terminal. A temperature compensator for span adjustment is provided between one of the input terminals and the DC power source. A constant current control unit for feeding a constant current to the bridge circuit is provided between the other input terminal and the DC power supply.

Abstract: The voltage drops across a series-connected pair of strain gauges and arbitrary resistance are measured at zero and maximum stresses at three temperatures. The appropriate resistance for span compensation at the two extreme temperatures is then calculated from these values. The span compensation resistance is then distributed between a first resistor connected in series with one of the strain gauges and a second resistor connected in series with the other strain gauge. Initially, the first resistor is assigned a value of one ohm and the second resistor the remainder. With these values the series/parallel resistances required for temperature compensation at zero stress are calculated for the two extreme temperatures. The outputs at zero stress are then calculated for both the maximum temperature and the intermediate temperature and the difference between these outputs is obtained.

Abstract: Pairs of strain gauges are symmetrically disposed on a bearing support structure and feed signals to indicating and/or recording devices to indicate bearing load conditions.