SU838408A1 - Digital thermometer - Google Patents

Description

(54) DIGITAL THERMOMETER

one

The invention relates to temperature measurements, namely, digital thermometers 1M with correction of non-linearity of the temperature transducer.

A digital thermometer is known, in which a non-linearity of a thermal converter is corrected, comprising a thermal converter, a counting pulse generator, a key, a derivative sign determining circuit, a pulse addition and subtraction circuit, a pulse counter l.

However, this digital thermoment does not provide high precision temperature measurement.

The closest to the technical essence of the invention is a digital thermometer containing a thermocouple connected to the input of an analog digital converter, the output of which is connected to a memory unit, a display unit and a control unit connected to the control input of the analog-digital converter and memory cell, B This device corresponds to each value of the signal from the output of the thermal converter corresponding to the value of the temperature from the output of the memory flea l2.

However, this device does not provide high measurement accuracy over a wide range of temperatures, since it requires a large amount of storage unit to obtain high measurement accuracy.

The purpose of the invention is to increase the temperature measurement.

The goal is achieved by

0 that the adder and the register are connected in series to the digital thermometer, the synchronizing input of which is connected to the output of the analog-digital converter, and the output

5 is connected to the input of the display unit and the first input of the adder, the second input of which is connected to the output of the memory unit, with the control inputs of the adder and the register connected to the unit

0 control

FIG. 1 shows a block diagram of a digital thermometer; in fig. 2 is a graph of the output voltage of the thermal converter as a function of temperature.

5 and its approximation by a piecewise linear function.

Claims (2)

The digital thermometer circuit contains a thermal converter 1, an analog-to-digital converter (ADC), which includes a voltage converter 2 in a burst and a pulse counter 3, a cyMviaTop 5 memory unit 4, a register 6, a display unit 7 and a control unit 8. Digital thermometer works as follows. Thermal converter 1 converts the temperature to a voltage. From the output of the thermal converter, the voltage is supplied to the input of the converter 2 of the voltage in a burst of pulses, which is part of the ADC, which converts the voltage of the thermal converter to a burst of pulses. A burst of pulses is fed to the input of counter 3 and to the clock input of register 6. The address inputs of memory block 4 are connected to pulse counter 3 so that when the first K pulses of the first pack arrive, a number corresponding to the temperature increment appears at the memory block output t for the integral of temperatures 0-ft (Fig. 2, when arriving from K to 2K-1 pulses at the output of the memory unit, a number appears corresponding to the temperature increment /Xt.j for the temperature interval C, t / 2, and t. d. for the entire temperature range of the device. Before changed The counter 3 and register b are zeroed. When the first pulse arrives at the counter, the output of the memory block is a number corresponding to At, y, and the output of the register b is zero. The totalizer input is fed by the number & t from the memory block and zero register.with adder output the summed up value of these two values is applied to register 6. When the first pulse arrives from converter 2, the input of register b to b is synchronized; register b records the code at the adder output, i.e., the corresponding & t. When the second pulse arrives from converter 2, a number corresponding to the value of At is written to the register, and when K-1 pulses arrive, the number corresponding to (K-l) ut is written to the register. When K arrives, the code of the higher bits of counter 3 changes and a number corresponding to utg for the temperature range t, t температур appears at the output of the memory block. At the arrival of each pulse, the value of the signal at the register output increases by Atxj. After the arrival of the last pulse, the register b gives to the display unit 7 the value of the temperature, corresponding to the approximation polyline. After a predetermined period of time, the control unit 8 returns all the blocks to the initial state and the thermometer starts a new measurement cycle. The presence of new elements in the digital thermometer - adder and register favorably distinguishes it from the device known, as it allows to increase the temperature measurement accuracy with a small volume of the memory block. DETAILED DESCRIPTION OF THE INVENTION A digital thermometer comprising a thermal converter connected to an input of an analog-digital converter, an output of which is connected to a memory unit, a display unit and a control unit connected to control inputs of an analog-digital converter and a memory unit, a tl and h In order to improve the measurement accuracy, a sequentially connected adder and a register are entered into it, the synchronization input of which is connected to the output of the analog-digital converter, and the output is connected to the input of the display and the first input of the adder, the second input of which is connected to the output of the memory unit, and the control inputs of the adder and the register are connected to the control unit. Sources of information taken into account in the examination 1.Kollatay, Harkonen. Digital linearization of measurement results, Electronics, 1968, No. 5, p. 26-3. 2. The UK patent number 1390837, cl. G 1 N, pub. 1975 (prototype).