CS237199B1 - Temperature sensing unit with monostable trigger circuit - Google Patents

Abstract

The invention relates to a monostable temperature sensor a flip-flop that allows in conjunction with a microcomputer, an immediate indication temperature of measured medium in digital form. The essence of the invention is that it is thermally the dependent resistive element is connected to one timing connection point a member of a monostable flip-flop, a capacitor a timing member is connected between two. timing member bddy monostable flip-flop, with to the input of the monostable flip-flop one output channel line is connected microcomputers and monostable output the flip-flop is converted to a line microcomputer input channel.

Description

(54)

Temperature sensor with monostable flip-flop

The present invention relates to a temperature sensor with a monostable flip-flop which, in conjunction with a microcomputer, enables an immediate indication of the temperature of the medium to be measured in digital form.

The principle of the invention is that the temperature-dependent resistive element is connected to one connection point of the monostable flip-flop timing member, the timing member capacitor being connected between two. a monostable flip-flop timing connection bddy, wherein a single microcomputer output channel line is connected to the monostable flip-flop input and the monostable flip-flop output is converted to the microcomputer input channel line.

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The invention relates to a temperature sensor with a monoetabile flip-flop which enables, in connection with a microcomputer, an immediate indication of the temperature of the medium to be measured in digital form.

Most of the known circuitry for temperature sensing and registration and further processing by a microcomputer utilizes temperature-dependent resistive elements that are part of the measuring bridges. The analog output signal is then converted to digital form by analog to digital converters for computer processing. The disadvantage of this solution is the complexity of wiring the measuring bridges and analogue to digital converters, occupying wolf lines of the input channel of the microcomputer for parallel transmission of temperature information. These disadvantages are partly overcome by the already known temperature sensors comprising: relaxation element with capacitor and temperature-dependent resistive element. Changing the temperature of the sensing element, such as thermistors, causes a change in its resistance and changes the discharge time of the capacitor in the relaxation member. Thus, the temperature of the measured mode is converted to change the oscillator frequency or oscillation period. The disadvantage of all these sensors is the non-linearity of the oscillator frequency-temperature dependence. This is eliminated in a number of specialized circuits that use some electronic components (diodes, resistor and capacitor combinations) to compensate for the non-linear characteristics of some electronic components. This leads to an increase in the number of wiring elements and additional errors due to changes in non-linear element parameters (eg aging)

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- 2 and the difficulty of their selection in the event of replacement. When connected to a microcomputer, these circuits are unnecessarily complex and do not take advantage of the software solution, which is given by using a microcomputer to process the signal from the sensors ·

These disadvantages are overcome by the temperature sensor according to the invention # consisting of a tee element formed by a capacitor and a temperature-dependent resistive element. As a temperature sensor, and a monostable flip-flop connected by two epoji to a microcomputer, characterized in that the temperature-dependent resistive element is connected to one connection point of the timing member of the monoetable flip-flop, the capacitor of the timing member is connected between two A single microcomputer output channel line is connected to the monostable flip-flop input, and a monostable flip-flop output is fed to the microcomputer access channel line.

The advantage of this circuit according to the invention is maximal simplicity of connection, no analogue to digital converter is needed, the sensor occupies only one line of input e output channel of microcomputer. animation of elements during calibration, replacement, etc.

BRIEF DESCRIPTION OF THE DRAWINGS The principle of the invention will be explained in more detail on the circuit shown in the accompanying drawing.

The temperature sensor according to the invention consists of a monostable flip-flop 4, to which it is connected to the C ^ Ry

- 3 237199 g _{aiV a sien} 5, which consists of a temperature-dependent resistive element Rt and capacitors C. The temperature-dependent resistive element R * is further connected to a DC + U 'power source. output channel OP microcomputer 3 ·

The output 4 of the monostable flip-flop 4 is connected via a link 2 to the input channel of the microcomputer IP.

Temperature measurement is performed using a temperature-dependent resistance element R _T (e.g., a thermistor) which is part of the timer 5 monostable circuit 4. The time rollover monostable circuit 4 is given by

T ® R * «C · ln2 where T is the flipping time of the monostable flip-flop

R resistance value of the temperature-dependent resistance element

C ^T value of capacitors of timing element ln2 natural logarithm of number 2

The conversion of the time T to the numerical value is ensured by the software while respecting the characteristic of the temperature-dependent resistance element R *. The actual temperature measurement is initiated by the start pulse, which is brought from the output channel OP microcomputer 3 flipping of the monostable flip-flop 4 (Q ' log 1) and programmatically treating the IP channel of the microcomputer 3, where the input level and increment value test is performed in the program loop, proportional to the time of flipping, Then the operations in which the flipping time is converted to the measured temperature value, which is written into the memory of the microcomputer 2, follow.

237 199 and is ready for further use · Furthermore, the entire temperature measurement procedure can be repeated with the same sensor, possibly via

And other input and output channel lines in the microcomputerX, temperatures are sensed through additional sensors ·

The sensor has been tested in conjunction with an automatic meat compounding device. It has proven all the expected benefits, good measurement accuracy and reproducibility and high operational reliability.

The sensor according to the invention can also be used in all temperature measuring devices in which the signal processing and evaluation is carried out in digital form.

Claims (1)

SUBJECT OF THE INVENTION 237 199 A temperature sensor with a monostable flip-flop consisting of a capacitor timing element and a temperature-dependent resistive element as a temperature sensor, and a monostable flip-flop connected by two connections to a microcomputer, characterized in that the temperature-dependent resistor (R _t ) is connected to (CyR). ) of the monostable flip-flop (4), the capacitor (C) of the timing member (5) is connected between the point (CjRy) and the point (C _T ) of the monostable flip-flop (4), the input (B) of the monostable flip-flop (4) connected by the connection (1) of the microcomputer output channel line (3) and the output (Q) of the monostable flip-flop (4) is connected via the link (2) to the microcomputer input channel line (3) ·