SU823900A1 - Device for measuring temperature - Google Patents

Description

(54) DEVICE FOR MEASURING TEMPERATURE

The invention relates to a technique for measuring temperature and can be used in measuring equipment with the highest accuracy requirements for measuring the temperature of objects with variable parameters and low thermal conductivity, for example, in medical equipment. A device for measuring temperature is known, in which, for increasing the speed, correction circuits and predictive filters are used. The device contains a series-connected temperature-to-voltage converter, a correction amplifier circuit and a recording device. The correction circuit is tuned to compensate for the time constant of the temperature sensor I1J. However, the actual transient at the output of the sensor is determined not only by the constant time of the sensor, but also by the amount of thermal resistance between the sensor and the object of measurement. Therefore, the known device can provide high measurement accuracy. The closest in technical essence to the present invention is a temperature measuring device containing a series-connected temperature converter and a differentiator, two threshold units, the inputs of which are connected to the output of the differentiator, and a recording device 12. The known device does not provide sufficient accuracy in measuring slowly changing . This is due to the instability of the analog circuitry of the device when storing information. The purpose of the invention is to improve the accuracy in measuring slowly varying temperatures. The goal is achieved by including a key and a voltage divider with combined inputs connected to a temperature converter, a voltage converter into a number of pulses, a reversible counter, a mixer and two pulse drivers, the inputs of which are connected to the inputs of the corresponding threshold units. and the outputs to the control inputs of the reversible counter and the inputs of the mixer, to the output of which one input of the voltage converter is connected to the number of pulses.

The other input is connected to the outputs of the key and the voltage divider, and the output to the input of the reversible counter, the output of which is connected to the recording device, and the control input of the switch is connected to the output of one of the pulse shapers.

FIG. 1 shows a block diagram of the device, and FIG. 2 shows oscillograms, as is shown in its operation.

The device for temperature measurement includes a temperature converter 1, a differentiator 2, a threshold unit 3, a pulse shaper 4, a threshold block 5, a pulse shaper b, a switch 7, a voltage divider 8, a pulse mixer 9, a voltage to pulse converter 10, a reversible counter 11, the recording device 12.

The device works as follows.

After connecting the sensor to the measurement object at the outputs of the temperature converter 1 and differentiator 2, the signals U and 2 begin to change (Fig. 2). At time t, the derivative reaches the threshold of threshold unit 3, the latter triggers the pulse shaper 4, a short pulse of which goes to the control input of the key, controls the input of the reversible counter 11 and through the mixer to the trigger input of the voltage converter 11 to the number of pulses. At time t, key 7 is closed (does not shunt the voltage divider), the signal U (t) of the temperature converter 1 through the voltage divider 8 with the transfer coefficient at enters the input of the voltage converter 10 into the number of pulses triggered at time t, from the output of which The number of pulses proportional to N is input to the reversing input of the counter; KVi (t2) KBV (see also in Fig. 2), which will be counted by the counter in the reversing direction, since the first control input of the counter at time t was fed start impulse (K - transfer coefficient ovatel 10 voltage pulses in number). At the moment t2, the output signal of the differentiator 2 reaches the response threshold of the threshold unit 5, the latter triggers and starts the pulse former, the output signal of which goes to the second control input of the reversing counter 11 and through the mixer 9 to the start input of the voltage converter 10 in the number of pulses. Since, at the moment, the key 7 is closed, then the signal is passed to its output without. change (key shunts voltage divider). In pesyjibTaTe, since the second control input (direct count) of the reversing counter 11 at the time tz was

a start impulse was given, and in the counter itself the number N was counted backwards; at time t2, the number will be recorded on the counter

(V2-BV;) (1) If you select the voltage transfer ratio of the voltage converter to the number of pulses equal to (lb), where c (, 1 is the constant dimensional coefficient, and (t2) / U2 (t) is the voltage divider transfer ratio of 8, then the number N defined by expression (1) will be an exact analogue of the measured value for any value of the time constant of the transient process.

The same result can be achieved by using, instead of a reversible counter, two simple counters and a code reading device,

I,

The temperature converter, the differentiator and the voltage converter into the number of pulses are built upon implementation on the operational amplifiers, the key is on the transistor, the voltage divider is two resistors, the other blocks are easily built on the basis of logic elements.

The proposed device has a higher accuracy of measurements. Slowly varying temperatures by comparison with the prototype.

Claims (2)

Invention Formula A temperature measuring device comprising in series soy; a cinnamon temperature transducer and a differentiator; two threshold units, the inputs of which are connected to the output of the differentiator, and a recording device characterized in that. In order to increase the accuracy in measuring slowly varying temperatures, a key and a voltage divider with combined inputs connected to a temperature converter, a voltage converter in the number of pulses, a reversive counter, a mixer and two pulse drivers, whose inputs connected to the inputs of the respective threshold units, and the outputs to the control inputs of the reversible counter and the inputs of the mixer, to the output of which one input of the voltage converter is connected to the number of impulses s, the other input of which is connected to the outputs of the key and the voltage divider, and an output - to an input of down counter whose output is connected to the recording device, wherein the control key input connected to the output of a pulse shaping. Information taken into account in the examination., 1. Handbook of systems engineering, Tsarev, from English, ed. R.Nakola. M ,, Soviet radio, 1970, pp.478-479. 2. USSR author's certificate in application 2717789/10, class C. 01 K 7/16 1979.