SU879481A1 - Device for measuring resistance increment - Google Patents

Description

(54) DEVICE FOR MEASURING RESISTANCE INCREASES

I

. The invention relates to a measurement technique and can be used to measure the increments of resistance of resistive transducers, such as resistance strain gages.

A device for measuring active resistances comprising a bridge circuit consisting of a measured resistance, two resistors and a capacitor connected in series with the load resistance, a power supply unit of the bridge circuit, a comparison circuit made on diode 1, is received. power bridge circuit, causing in the last transient. At the moment of equilibrium of the bridge circuit, the diode is cleared, and the formation of the duration of the output pulse is completed. The duration of the output pulse is proportional to the resistance being measured. The disadvantage of it is that the sensitivity of this device

When measuring the increment of resistance, it is small and is determined by the constant time of the RC circuit, the limit of increase of which is limited by considerations of the speed of the device.

It is also known a device comprising a bridge circuit consisting of active resistances and a sensitive element, an amplifier, a comparison circuit 10 and an integrator 23.

A disadvantage of the known device is that it is sensitive. This is small, since it determines 5 with the gain transfer factor of the amplifier, the increase of which is limited by the conditions of stable operation and the required stability. In addition, the use of the full amplitude range

Claims (2)

The 20 amplifier for generating the output signals of the device degrades the measurement accuracy due to the non-linearity of the amplitude response. The aim of the invention is to increase the sensitivity and accuracy of the device. This goal is achieved by the fact that the device for measuring the increment of the SRI of resistance, containing a bridge circuit with a sensitive element, the measuring diagonal of which includes an amplifier, and the diagonal of the power supply is connected between the common bus and the output of the comparison unit, one input of which is connected to the output of the amplifier, integrator , the input of which is connected to the output of the comparator unit, is supplied with a model resistor connected between the integrator's output and one of the vertices of the measuring diagonal of the bridge circuit, and -diagonali second bridge circuit is connected to another vhodom- block comparison. The functional diagram of this device is shown in the drawing. The device consists of a bridge circuit 1 with a sensing element 2, an amplifier .3, a comparison unit 4, an integrator 5 and an exemplary resistor 6. The measuring diagonal of a bridge circuit 1 with element 2 includes an amplifier 3, the output of which is connected to the input of block 4. The output of block 4 connected to the input of the integrator 5 and one vertex of the power diagonal of bridge circuit 1, and the other of which is grounded. Resistor .6 connects the output of the integrator 5 to one vertex of the measuring diagonal of bridge circuit 1, and the other to the top of the measuring diagonal is connected to another input of block 4. The output voltage of block 4 is supplied to the diagonal of the power supply of circuit 1 and to the input of the integrator 5. Ex. The imbalance of circuit 1, caused by the increment of the resistance of element 2, begins to decrease to zero under the action of voltage from the output of integrator 5, which enters one measuring diagonal of circuit 1 through a resistor 6. At the time of between the input unit 4 is also equal to zero. - Block 4 triggers, and the polarity of the voltage at its output changes. This changes the polarity of the voltage 14 of the imbalance of circuit 1 and the direction of integration of the integrator 5. The process of balancing bridge circuit 1 is repeated. The pulse period of the power supply circuit 1 is proportional to the increment of the resistance of the element 2. The sensitivity of the device depends on the resistance of the resistor 6 and can be increased by increasing the resistance of this resistor without degrading the operation of other elements of the device. The measurement accuracy of the device is higher, since the operation of block 4 occurs at one value of the output voltage of the amplifier, 3. In this case, the nonlinearity of the amplitude characteristic of the amplifier 3 does not affect the formation of the output signal of the device. Thus, in the proposed device, its sensitivity and measurement accuracy are increased. The invention The device for measuring the increments of the resistance, containing a bridge circuit with a sensitive element, the measuring diagonal of which includes an amplifier, and a diagonal power supply is connected between the common bus and the output of the comparison unit, one input of the comparison unit is connected to the output of the amplifier, the integrator, the input connected to the output of the comparison unit, characterized in that, in order to increase sensitivity and accuracy, it is equipped with an exemplary resistor connected between the integrator output and one of the peaks, measure the flax diagonal of the bridge circuit and the top of the measuring diagonal of the bridge circuit is connected to another input of the comparison unit. Sources of information taken into account during the examination 1. V. Ilyin. Pulse devices with bridge elements. - M.-L., Energie, 1965, p. 39 2. Nart women A.I. and others. Transducers of electrical parameters of control and measurement systems. - M., Energie, 1976, p. 287, fig. 10 (prototype)