SU1536218A1 - Device for measuring temperature - Google Patents

Abstract

The invention relates to temperature measurements and allows for increasing the speed and accuracy of temperature measurements. The output signal of the control unit 5 controls the analog-to-digital converter / ADC / 6 converts the voltage AND from the output of the primary measuring converter 1, proportional to the temperature, to the code N, which is written into the reversible counter 7. Pulses with a frequency F ₀ come from the output of the pulse generator 10 through the first key 12, controlled by the trigger 8, to the subtracting input of the counter 7 and the input of the binary multiplier 2, which includes a code converter to the frequency 4 and a reversible counter 3. To the counting input of the counter 3 is fed through the second key 13 pulse s with a frequency F ₀ from the output of the frequency divider 11. At the moment of zeroing the meter 7 the keys 12, 13 are closed, in the binary coded decimal down counter result code 9 is formed linearly associated with the measured temperature. 1 il.

Description

round 0, to the code N, which is written into the reversible counter 7. Pulses with a frequency f0 are output from the generator 10 pulses through the first key 12, controlled by the trigger 8, to the subtracting input of the counter 7 and the input of the binary multiplier 2 that includes the converter 4 code in the frequency and reversible counter 3. On

the counting input of the counter 3 is fed through the second key 13 pulses with a frequency fD from the output of the frequency divider 11. At the moment of resetting the counter 7, the keys 12, 13 are closed, in a binary-decimal reversible counter 9 of the result a code is generated that is linearly related to the measured temperature. 1 il.

The invention relates to temperature measurements, namely, devices for measuring temperature with correction of non-linearity of thermal converters, and can be used for accurate temperature measurements.

The aim of the invention is to improve the speed and accuracy of measurement.

The drawing shows a functional diagram of the device.

A device for measuring temperature contains a primary measuring transducer 1 that converts temperature into voltage, a binary multiplier 2, which includes a reversible counter 3 connected by code buses, and a transducer 4 codes to a frequency, the frequency input and output of which are respectively the input and output of binary multiplier 2 , control unit 5, analog-to-digital converter 6, reversible counter 7, trigger 8, binary-decimal counter 9 of the measurement result (for example, performed reversing), generator 10 pulses, the frequency divider 11, the first key 12 and the second key 13.

For the majority of used primary measuring transducers of temperature to voltage, the relationship between the temperature in and the output signal of the converter U can be represented as

 ± b, and ± ci1,

(D

where b0, b,

and b - constant coefficients. At the beginning of the measurement cycle, the voltage pulse from the first output of the control unit 5 is fed to the bus

start-up of the analog-digital converter 6, starts the last one, at the output of which a parallel code N is set, proportional to the output voltage U of the primary measuring converter 1:

N kU,

(2)

0

five

0

five

0

five

where k is the conversion factor of the analog-to-digital converter.

With a delay equal to the speed of the analog-digital converter 6, the voltage pulse from the third output of the control unit 5, which is fed to the write buses of the reversible counters 3, 7 and 9, records in the reverse meters 3 and 9 the numbers corresponding to the codes of their initial settings, tires which are connected to the information inputs of these counters, and in the reversing counter 7 - recording the number corresponding to the output code of the analog-digital converter 6 "Following the recording of the numbers, the voltage pulse from the second output of the control unit 5, stepping into the input Setting the trigger unit 8, sets the trigger 8 to the unit state, so that a high voltage level set at its output and fed to the control inputs of the keys 12, 13, gives permission for the passage of pulses through them with frequencies f0 and f0 arriving at their inputs from the outputs of the generator 10 pulses and 11 frequency divider.

Pulses with a frequency of f0, coming from the output of the first key 12 to the subtractive input of the reversible counter 7, reduce the previously recorded in it

515

the number N. At the moment when this counter passes through zero, a voltage pulse appears at its zero output, which, arriving at the input Setting zero of trigger 8, returns the latter to the initial zero state. In this case, at the output of the trigger 8, a pulse is generated with a duration of

P

NT

kU

R

Simultaneously with the beginning of the formation of the time interval, the pulses with frequencies f0 and f 0 from the outputs of keys 12, 13 are received respectively at the frequency input of the 4-frequency converter and the counting input of the reversing counter 3 of the binary multiplier 2. The output frequency of the binary multiplier is equal to the output frequency of the converter 4 code to frequency is determined from

f f 1

YO ° 2

N.

where N (is the output code of the reversible counter 3;

k, is the conversion coefficient

4 code to converter

frequency;

n is the number of bits of the converter 4 codes in the frequency, equal to the number of bits of the reversible counter 3.

If the initial installation of the reversible counter 3 is equal to B (, then at each instant of time t in the interval Tp of conversion, the output code of the reversible counter 3, the code to the frequency arriving at the code buses of the converter 4, will be equal to

N, B, ± f0

t.

(five)

In this expression, the + sign will stand when the output of the key 13 is connected to the summing input of the reversible counter 3, and the sign - when the output of the reversing counter 3 is connected to the subtracting input.

From the frequency output of the binary multiplier 2 to the counting input of the binary-decimal reversible counter 9 of the measurement result, during the conversion time Tn, the number of pulses N, equal to

N, S f

dt

  -I (B.tfL. T) -dt,

(6)

Yu

 -

If the initial setting of the binary-decimal reversible counter 9 of the measurement result is equal to B0, then by the end of the conversion time IB, the number of pulses N, equal to

N3 B0

± n

7

(7)

(6) in (7) and

where kt is the division factor of the divider 11, we get

Substituted the expression into account that f 0 fQ / k,

B0 ±

 AT,

T8

and

+

P 1

2 -k

U

(four)

25

(eight)

Subject to equality

k 2

§one

with(

b / i

ktw

(9)

what is easily achieved by the choice of k values, the relation

corresponding- b, I, will

N 3 "/ b

(YU)

where d. - coefficient of proportionality.

For convenience of reference, the coefficient d is chosen to be a multiple of ten, and since the result of temperature measurement is presented in a binary-decimal code, the reading of this result in digital indication is not difficult.

The control unit 5 can be made in the form of a pulse distributor, which at its outputs generates a sequence of control pulses in accordance with the operation algorithm of the device.

The modes of counters 9 and 3 are determined based on the polarity of the first and second derivatives of the transform function (1). The reversible meter 9 of the measurement result must

set to add mode if the first derivative of the transform function is positive, and to subtract mode if the first derivative of the transform function is negative. In the first case, the transformation function monotonously increases, in the second, monotonously decreases.

The reversible counter 3 is set to the add mode, if the sign of the product of the first and second derivatives is positive, and to the subtraction mode, if it is negative.

Claims (1)

Invention Formula A temperature measuring device containing a primary measuring transducer connected to the input of an analog-to-digital converter, the control input of which is connected to the first output of the control unit, and the output connected to the information input of a reversible counter, a binary multiplier that includes a counter connected by code buses pulses and code to frequency converter, generator them five " five pulses, characterized in that, in order to increase speed and accuracy of measurement, a binary-decimal meter of the measurement result, a frequency divider, the first key, the second key and a trigger, the input of the unit of which is connected to the second output of the control unit, the output is connected to it to the control inputs of the keys, and the input Setting zero is connected to the zero output of the reversible counter, the recording input of which is connected to the third output of the control unit connected to the recording inputs of the binary multiplier counter and the binary ten of the measurement result, the counting input of which is connected to the output of the code converter to the frequency of the binary multiplier, whose input is connected to the subtractive input of the reversible counter and the output of the first key, while the output of the pulse generator is connected to the input of the first key and the input of the frequency splitter, the output of which is through the second the key is connected to the counting input of the binary multiplier counter.