SU665217A1 - Temperature-measuring device - Google Patents

Description

one

The invention relates to the field of temperature measurement and can be used for accurate temperature measurements with numerical results.

A device for temperature measurement, built on the principle of pulse conversion time, is known. The device contains a thermal converter, an amplifier, a zero-organ, a key, a clock pulse generator, a pulse counter, a digital readout unit, a function generator.

The disadvantages of this device are low noise immunity and accuracy.

The most accurate and robust are digital devices integrating time-pulse conversion.

Of the known devices, the closest to the invention in its technical essence is a temperature measuring device comprising a series-connected thermal converter, an amplifier, two clock switches, an integrator, a zero-organ and a key connecting the clock generator to the counter and the digital readout unit, and in parallel the integrator capacitor through the second switch clock included resistor 2.

A disadvantage of the known device is low accuracy, since the adjustment of the integration time for the interference period leads to significant measurement errors.

The purpose of the invention is to improve the measurement accuracy.

To achieve this device, a device containing a thermal converter, an amplifier, a first clock switch, an integrator, in which a resistor, a zero-organ and a key connecting a clock generator with a counter and a digital readout unit are connected via a second clock switch to the capacitor. also a control unit and a reference voltage source, an additional common-mode first clock switch and an integrator are introduced, and the integrator input is connected to the source via an additional clock switch ohm of the reference voltage, and the output is at the input of the null organ.

The drawing shows a block diagram of a device for measuring temperature.

Claims (2)

The device contains a thermoconverter 1 connected in series, an amplifier 2, a first switch of 3 cycles, an integrator 4 with a resistor 5, a zero-organ 6, a switch 7, connecting the generator 8 clock pulses with a counter 9 and a digital reference unit 10, and parallel to the integrator capacitor 11 through The second switch of 12 clocks includes a resistor 13, as well as an integrator 14, whose input through the switch of 15 clocks is connected to the source 16 of the reference voltage, and the output to the second input of the zero-body through the resistor 17, with all the keys Nena to the control unit 18. The apparatus operates as follows. In the first clock cycle switches 3 and 15 are closed, and the switch 12 is open. During the time interval of 7 ", capacitors And and 19 are charged from voltage U (and t / |., Respectively, where iLe is the voltage of the thermal converter after amplification and subtraction of the constant, independent of the temperature, members of its interpolation control; K - gain factor amplifier 2; UH - source voltage; c - temperature; t / i, T - constant coefficients. The plus and minus signs in front of the / G member correspond to the monotonically increasing and monotonically decreasing characteristics of the thermal converters. The output voltages of the integrators 4 and 14 are at the end first t Kta are determined by the corresponding expressions. U, -UJ, IR, C ,, - (1). (2) In the second cycle, switches 3 and 15 open and switch 12 is closed. Condenser 11 is discharged through resistor 13. Discharge By the exponential law, before the voltage of the CNF, the moment of equality From and Uu, the discharge of capacitor 19 to zero occurs. The discharge time of capacitor I is determined by the expression Te R ,, C ,, lnU, IU. (3) Fill the time interval Te with pulses from the generator 7 taking into account expressions (1) and (2), we have DGf D П In 1 Л / е / оХ, з (-11 Ш --- fuRi Cii Fulfill the condition Г, expression (4) accepted maet view Ns A + e, (5) ,, 1H ilSp constant coefficient. As can be seen from expression (4), the change in Г ", due to the adjustment of the integration time for the interference period, does not affect the measurement accuracy. When providing high noise immunity in a known device, i.e., when adjusting Hz for the interference period, the measurement error is determined by the range of variation of TC and can reach several percent. The proposed device allows to increase the measurement accuracy while ensuring high noise immunity. In addition, the device is much simpler than the known devices of similar purpose. The invention A temperature measuring device comprising a thermocouple, an amplifier, a first clock switch, an integrator in which a resistor, a zero organ and a key connecting a clock generator with a counter and a digital readout unit are connected via a second clock switch to the capacitor The control and reference voltage source, characterized in that, in order to increase the measurement accuracy, additional common-mode signals are introduced into the first switch and integrator, and that input of the integrator through an additional switch cycles is coupled to a source of reference voltage, and an output - to the input of the zero-body. Sources of information taken into account in the examination 1.Zory V. I. and others. Lime universities. Instrument Engineering, 1976, No. 7, p. 112-116. 2. Semenov B. F. A digital thermometer with a linear scale. Proceedings of MEI, vol. 254, p. 136-137.