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Semiconductor strain gauge with temperature compensator

  • US 4,173,148 A
  • Filed: 10/05/1978
  • Issued: 11/06/1979
  • Est. Priority Date: 10/07/1977
  • Status: Expired due to Term
First Claim
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1. In a semiconductor strain gauge with a temperature compensator having a bridge circuit with four arms including semiconductor strain gauge elements to which pressure or strain is applied, said bridge circuit having input terminals for coupling a DC power suply with a pair of diagonally opposite junctions of said bridge circuit per se and output terminals for driving an output of said bridge circuit from a pair of remaining diagonally opposite junctions of said bridge circuit, initial zero-point temperature compensators each connecting in series and in parallel to each of semiconductor strain gauge elements on adjacent two arms of said bridge circuit and each comprising resistors for equalizing the resistance values and the temperature coefficients of all the semiconductor strain gauge elements when no pressure or strain is applied to the semiconductor strain gauge elements on the four arms, and a first temperature compensator for zero-point shift adjustment which is provided between the arms closer to one of the output terminals and is comprised of resistors for making the temperature coefficient of said first temperature compensator equal to that of the sensitivity of the semiconductor strain gauge element, the improvement wherein said first temperature compensator for zero-point shift adjustment is comprised of:

  • a first circuit including a temperature sensitive element with a positive primary temperature coefficient and a resistor connecting in series to the temperature sensitive element;

    a second circuit including a parallel circuit including a thermistor and a resistor connecting in parallel to the thermistor and a resistor connecting in series to the parallel circuit;

    a third circuit including a fixed resistor and a variable resistor with a common terminal connecting in parallel to the fixed resistor, the common terminal of the variable resistor connecting to one of the output terminals which is closer to the common terminal per se, said first to third circuit being connected in parallel and wherein B constant of the thermistor falls within a range 2,000°

    K. to 3,000°

    K. and the resistance value of the thermistor falls with a range 0.5 KΩ

    to 5 KΩ

    , and the resistance value of the temperature sensitive element with a positive primary temperature coefficient falls within a range 0.5 kΩ

    to 5 KΩ

    .

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