SU678334A1 - Temperature measuring device - Google Patents

Description

(54) DEVICE FOR MEASURING TEMPERATURE

additional clock digital processing of the output code, which reduces its speed.

The aim of the invention is to improve noise immunity. In the proposed device, this is achieved by additionally introducing a large-scale converter and a binary frequency multiplier equipped with an additional collecting circuit, which is its second input, and the second output of the selector is connected to the first through a large-scale converter. the output of the clock switch, and the output of the main collecting circuit is connected to the second input of the additional, collecting circuit, whose || sod is connected to the input row counter result.

The drawing shows a diagram of the device.

It contains a converter of temperature 1 to voltage, a preamplifier 2, a reference voltage source 3, a 4 clock switch, an integrator 5, a comparison device b, a pulse generator 7, a control unit 8, a selector 9, an additional collective circuit 10, a result counter 11, digital indicator 12, block 13 of the matching circuits, main collecting circuit 14, scale frequency converter 15, 16 — reversible counter, binary, frequency multiplier 17.

The input of the integrator 5 in the first cycle receives the voltage from the output of the preamplifier

and, K (Ug - OtM), (1) where K is the gain factor;

Ue is the output voltage of converter 1; „

UCM is the bias voltage of the amplifier, given from source 3. If UtM is Ut, then

   KUa (1st). At the end of the first cycle, the voltage at the integrator output

for. - - | l- KU4 (1 - e), (2) where t is the integration time constant.

The subtracting input of the reversing pulse counter for time tj receives the number NI KM.n.fo tj of the frequency f ′ from the pulse generator, where Kp.the transfer efficiency of the large-scale converter 15. If the installation of the counter 2, where n is the number of common binary bits of the counters 11 and 16, the number written in it at the end of the first bar -2 -N.

The time tj of the second cycle of operation is determined from the equation tiUex tjUo,. (3)

where and is the exemplary detection of source 3, whence

KUi (i - e-)

(four)

1 and

-J

At the same time, the frequency pulses fp are fed to the input of the circuit 10 and the summing input of the counter 16. The number recorded in the counter at any given time t of the second cycle is equal to

2 - NI + fot.

Let the pulse frequency follow. owls at the input of the counter of the result f, at the output of the collecting circuit 14, because the output of the multiplier fj, then

fi fz, (5) where

And what is f .. f 11 m .i. l i.v f - f ig f | (2 - N + fot)

(6)

i - -. -2

Solving together equations (5) and (6) with respect to fi and f, we get

f TG (7)

Integrating expression (7) during the second clock cycle, we get the number of pulses received at the result counter. tf f,

"JlFf: t5t -2 i" i-fot) /;

 2 lnNi-2 In (N, -foti).

Substituting t from expression (4) we have

KUa. Cuutf

N (Nj-fe

When N, f, tj

TO have when you

Kua

bore knl. ( eight)

By

we get N,

that is, the number recorded in the result counter is proportional to the measured temperature, and the digital indicator can be calibrated directly in the temperature unit. At the same time, his readings, as can be seen from expression (7), depend neither on the constant integration time nor on the pulse frequency of the generator. This frequency is selected from the condition of permissible discretization error of the time interval t, and its stability is required only for the conversion time. In addition, the meter readings do not depend on the duration of the first integration cycle, which allows it to be adjusted to the period of the disturbance of the normal form.

Thus, the proposed technical solution allows increasing the noise immunity of the device and at the same time increasing its speed, since the measurement result is obtained at the end of the second integration cycle. Introduction to the device of new units allows, in addition, to measure the temperature in cases where the characteristic of the primary converter is described by the exponential function of temperature. Formula of the invention

A temperature measuring device comprising a temp converter; connected position

through a preamplifier to the first input of a clock switch, a voltage source connected to the second inputs of a preamplifier and a clock switch, the output of which is connected to the input of an integrator connected in series with the comparator and a control unit whose output is connected to the input of the switch of clock ticks and the selector input , to the second input of which the output of the generator pulse is connected, and the output of the selector is connected to the inputs of the binary multiplier 4acTotH, consisting of a reversible th counter, located at one of its input, block: schemes of coincidence, the collective scheme and the counter result j. which is the output of the frequency multiplier and the digital indicator connected to the input, two

The outputs of the result counter are connected to the input of the coincidence circuit block, the outputs of which are connected to the inputs of the collecting circuit, so that, in order to increase the noise immunity of the device, a scale converter and a binary frequency multiplier are additionally introduced. an additional collective circuit, which is its second input, and the second output of the selector is connected via a scale converter to the subtractive input of a reversible counter connected by a summing input to the first output one of the villages is one hundred, and the output of the main collective cxeNU is connected; QO is the second input of the additional srb :: virtual circuit, the output of which is connected to the input of the result counter. -., -, ...--, ...- ..,