Semiconductor strain gauge with temperature compensator
First Claim
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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Accused Products
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.
16 Citations
7 Claims
-
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
. - View Dependent Claims (2, 3, 5)
-
-
4. 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 supply 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 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, wherein a temperature compensator for span adjustment is provided between one of the input terminals and the DC power supply and is comprised of resistors making the temperature coefficient of the temperature compensator per se equal to that of each of the semiconductor strain gauge elements and further 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; and a third circuit including a fixed resistor and a variable resistor with a common terminal connecting in parallel to the fixed resistor, said first to third circuits being connected in parallel and wherein B constant of the thermistor falls within a range 2,000°
to 3,000°
K. and the resistance value of the thermistor falls within a range 0.5 to 5 KΩ
, and the resistance value of the temperature sensitive element with a positive primary temperature coefficient falls within a range of 0.5 to 5 KΩ
.
-
-
6. 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 supply 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 comprising a fixed resistor connecting in series to each of the semiconductor strain gauge elements on the adjacent two arms and another fixed resistor connecting in parallel to the former fixed resistor and the semiconductor strain gauge element and each further 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, two temperature compensators for zero-point shift adjustment each provided between the arms closer to one of the output terminals and each is comprised of resistors for making the temperature coefficient of the temperature compensator equal to that of the semiconductor strain gauge element, and a constant current control unit for feeding a constant current to said bridge circuit and provided between one of the input terminals and the DC power supply, wherein a temperature compensator for span adjustment is provided between the other input terminal and the DC power supply and is comprised of resistors making the temperature coefficient of the temperature compensator per se equal to that of each of the semiconductor strain gauge elements and the temperature compensators for zero-point shift adjustment and a temperature compensator for span adjustment each are comprised of a first circuit including a semiconductor diffusion type resistor 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, and a third circuit including resistors, said first to third circuits being connected in parallel, and wherein B constant of the thermistor falls within a range 2,000°
- to 3,000°
K. and the resistive value of the thermistor falls within a range 0.5 to 5 KΩ
, and the resistance value of the semiconductor diffusion type resistor with a positive primary temperature coefficient falls within a range 0.5 to 5 KΩ
. - View Dependent Claims (7)
- to 3,000°
Specification