SU1453192A1 - Temperature-measuring device - Google Patents

Abstract

This invention relates to thermal measurements and improves measurement accuracy. The device includes a thermocouple 1, an adder 2, a functional quadratic converter 3, a zero-organ 4, a start circuit 5, a pulse generator 6, a pulse counter 7, a digital-analog converter (D / A converter) 8 and a digital display unit 9. The output of the generator is connected to the counting input of the counter 7, the outputs of which are connected to the inputs of the DAC 8 and the block 9. The output of the DAC 9 is connected to the input of the converter 3 and one of the inputs of the zero organ 4. The output signal of the converter 3 and the thermocouple voltage 1 arrive at the inputs of the adder 2, the output of which is connected to another input of the zero-body 4. The output of the zero-body 4 is connected to the input of the generator 6 stop and the recording input of the block 9. The start input of the generator 6 and the installation input of the counter 7 are connected to the output of the startup circuit 5. Introduction to the device a pulse generator, a pulse counter and a digital-to-analog converter ensures that the output stepped sawtooth voltage is strictly dependent on the current time, thereby eliminating the inherent prototype measurement error due to the mismatch of the current values of these values, and accordingly increases the measurement accuracy. 1 il. 1 sd 09

Description

The invention relates to the field I of thermal measurements using thermocouples.

! The purpose of the invention is improving the accuracy of measurements.

The drawing shows a structural diagram of the proposed device.

The temperature measuring device comprises a thermocouple 1, an adder 2, a functional quadratic converter 3, a zero-element 4, a start-up circuit 5, a pulse generator 6, a pulse counter 7, a digital-to-analog converter (DAC) 8 and an indication-15 unit 9.

The device operates as follows.

At the beginning of the measurement cycle, the start circuit 5 generates a short pulse, resetting the counter 7 and starting the generator 6. As a result, with each pulse of the generator 6, the output counter code 7 increases linearly with the help of the 8-in-one DAC. the step-like sawtooth voltage C _p proportional to the time interval measured by the counter 7 and described by the expression of cams (U ₂ = Uc) the zero-organ 4 generates a signal that stops the operation of the generator 6 and writes to the display unit 9 the current value of the output code of the counter 7, proportional to the time interval from the moment the generator 6 is started until it stops.

With the appropriate choice of the coefficients Кп and К ₂ / К, = b: К, К = = с: К ² , where К is a constant coefficient, at this moment the equality * cs - b -ί- * с (-i-) s whence t = ΚΘ,

Thus, the time interval t, and therefore the code at the input of the display unit, are directly proportional to the measured temperature. Moreover, due to the rigid dependence of the output step-like sawtooth voltage of the DAC 8 from the current time value, a significant increase in the accuracy of measurements is achieved.

where K, is the coefficient of proportionality;

t is the current time.

With the DAC 8, the output voltage is supplied to the quadratic converter 3, where it is converted into a signal

U _k = k _g s ² , where K j is the coefficient of proportionality.

Acting on one of the inputs of the adder 2, the signal U _{k is} summed with the voltage of the thermocouple 1, which is equal to the purpose of increasing the pulse generator, where a, b, c

Θ

Output described

- constant coefficients;

- measured temperature voltage of the adder 2, the expression and?

E - U _to - a, is compared by the null-body 4 with the signal Un. At the moment of equality of these

Claims (1)

Claim A device for measuring temperature, containing a thermocouple, a functional quadratic converter, an adder, to the two inputs of which the outputs of the thermocouple and a functional quadratic converter are connected, a zero-organ, one of the two inputs of which connect the output of the adder, a start-up circuit, and a digital display unit, about the fact that, from the measurement point of view, a pulse converter and a digital-analog converter, wherein the output of the pulse generator is connected to the counting input of the pulse counter, the outputs of which are connected to the inputs of the in display and digital-to-analog converter, the output of which is connected to the input of the functional quadratic converter and the second input of the zero-organ, the output of which is connected to the stop input of the pulse generator and the write enable input of the display unit, and the output of the start-up circuit is connected to the installation input of the pulse counter and the start input of the pulse generator .