SU1744617A1 - Device for measuring environment parameters - Google Patents

Abstract

The invention relates to a measurement technique, in particular to instruments for measuring humidity, and can be used to measure humidity and the temperature of an environment or a material. The goal is to expand the functionality of the device. In addition to measuring the ambient humidity, the device simultaneously measures

Description

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About VI

its temperature. This is achieved by introducing a pulse voltage-duration converter 36 and a switch 33 into the switch 15 device circuit. Highly accurate measurements are provided by introducing a resistive divider 19 into the circuit, sampling and storage unit 16, and a code converter 38, which allows to linearize the curve depending on the duration of the heat pulse on the humidity of the studied medium or material and smooth out the possible nonlinearity of the dependence of the instantaneous voltage drop on the sensor 3, converted into a digital code, on the temperature atura

The invention relates to a measurement technique, in particular to instruments for measuring humidity, and can be used to measure humidity and the temperature of an environment or a material.

A device is known - a hygrometer containing a resistive electrode connected through a switch to a current source and connected to one of the measuring electrodes of the sensor.

The disadvantage of this device is the inability to measure the ambient temperature.

The closest to the proposed technical entity is a device containing a humidity sensor made in the form of a temperature-sensitive element, a measuring bridge, in one arm of which a temperature-sensitive element is included, a converter, a recording device, a power supply unit, a comparison circuit, a control circuit, a comparator of a thermal pulse duration , a recording device and a temperature-sensitive element, made in the form of a thermal radiator.

The disadvantages of the known device are low measurement accuracy, low sensitivity to the measurement of small moisture values of the medium under study, as well as measurement of only one environment parameter - humidity, which limits the functionality of the device.

The aim of the invention is to expand the functionality of the device.

The goal is achieved by the fact that a device for measuring humidity, containing a constant voltage source, a recording instrument, a sensor,

the study environment. The high sensitivity of the device to the measurement of small moisture values is achieved by covering the temperature-sensitive element with a film selective for NaO sorbent molecules. The device can be realized with autonomous power supply from small-sized batteries or a battery with a voltage of 9 V, or from a small-sized D2-15 voltage rectifier due to the supply voltage to the converter 38 and the counter 7 only for the measurement time of the selected parameter, which further reduces current consumed by the device. 4 or

A clock generator, made in the form of a temperature-sensitive element, three outputs of a constant voltage source are connected to the power inputs of a clock generator, a control unit and a comparator, a counter is entered, the reset input of which is connected to the first output of the control unit, the second, third and fourth outputs of which connected respectively to the control inputs of the switch and the sample and hold unit and the input of a DC source, the output of which is connected to the first input of the resistive divider and the second

the inputs of the switch and the block of sampling and storage, the output of which is connected to the first input of the comparator, the second input of which is connected to the output of the resistive divider, the second and third inputs of which

connected to the first and second outputs of the sensor, the second output of the generator of clock pulses connected to the counting input of the counter, the enabling input of which is connected to the recording input of the recording

the device and the first output of the key, the first input of which is connected to the output of the comparator and the first input of the code converter, the second input of the key is connected to the output of the voltage converter-pulse duration, the input of which is connected to the switch output, the output of the counter is connected to the second input of the code converter, the output of which connected to the information input of the registering device; seven outputs of the DC voltage source are connected to the power inputs of the meter, switch, DC source, sampling unit and x transducer, transducer

voltage-pulse duration, the registering device, the output voltage of the converter voltage reference-pulse duration, the input of the DC voltage source and the control input of the DC source are interconnected, the second output of the key is connected to the second input of the code converter.

Figure 1 shows a block diagram of a device for measuring environmental parameters; Fig. 2 is a block diagram of the control unit; FIG. 3 is a voltage-transducer voltage-pulse diagram; figure 4 - structural diagram of the resistive divider.

A device for measuring environmental parameters (Fig. 1) contains a constant voltage source 1, a recording device 2, a sensor 3 made in the form of a temperature-sensitive element, a comparator 4, a generator of 5 clock pulses and a control unit 6. Three outputs of a constant voltage source 1 are connected to the power inputs of the generator 5 clock pulses, control block b and comparator 4. The device also contains a counter 7, the reset input 8 of which is connected to the output 9 of control block 6, the second 10, the third 11 and the fourth 12 the outputs of which are connected respectively to the control inputs 13 and 14 of the switch 15 and the sampling and storage unit 16 and the input of the DC source 17, the output of which is connected to the first input 18 of the resistive divider 19 and the second inputs 20 and 21 of the switch 15 and the block 16 selection ki and storage, the output of which is connected to the first input 22 of the comparator 4, the second input 23 of which is connected to the output of the resistive divider 19, the second 24 and third 25 inputs of which are connected to the first 26 and second 27 outputs of the sensor 3. The output 28 of the generator 5 clock pulses connected with a counting input 29 of the counter 7, the enabling input 30 of which is connected to the input 31 of the recording of the recording device 2 and the first output 32 of the key 33, the first input 34 of which is connected to the output of the comparator 4. The second input 35 of the key 33 is connected to the output of the converter 36 -draw The pulse, the input of which is connected to the output of the switch 15. The output of the counter 7 is connected to the first input 37 of the converter 38 codes, the output of which is connected to the information input of the recording device 2. The seven outputs of the constant voltage source 1 are connected to the power inputs of the counter 7, switch 15 , DC source 17, sample and hold unit 16, converter 38 codes, converter 36,

voltage-pulse duration and the recording device 2. The output of the reference voltage of the source of constant voltage 1 is connected to the input of the reference voltage of the converter 36 voltage-pulse duration. The input of the constant voltage source 1 and the control input of the direct current source 17 are interconnected. Second exit 39

the key 33 is connected to the second input 40 of the converter 38 codes.

The device works as follows.

Sensor 3, made in the form of a temperature-sensitive element coated with a sorbent film, is brought into contact with the medium (material) under study.

Using key 33, the mode of recording information Humidity or Temperature is established by connecting the counter 7 of the output of the comparator 4 or the output of the converter 37 to the enable input 30, as well as by switching at the input 40 of the converter

38 level of logical zero to the level of logical units, respectively.

Unit 6 supplies a turn-on signal from fourth output 12 to source 17 connected to sensor 3 via a high-resistance

resistive voltage divider 19, for the purpose of temperature compensation of moisture readings. In this case, the counter 7 starts counting the clock pulses of the generator 6. On the sensor 3 there will be a voltage drop Uo, depending on the temperature of the medium (material) under investigation, and the output of the resistive divider 19 is voltage K, where is the division factor of the resistive divider 19. Eg Do by the signal from the third output 11 of block 6 is stored in block 16, and by the signal from the second output 10 of block 6, the switch 15 is turned off, and the voltage Uo is remembered in converter 36. Under

the current flowing through the sensor 3 begins to heat up, its resistance increases sharply and the voltage U0K at the output of the resistive divider 19 increases to Uo, and the rise time

Ti depends on the humidity of the test medium (material). When the voltages are equal on the first 22 and second 23 inputs of the comparator 4, an O signal appears at the output. If the key 33 is set to the humidity recording mode, the counting of the counter 7 stops, the output input 40 of the converter 38 is applied to level 1 from output 39 the key 33, and the converter 38 recodes the output code of the counter 7 into the readings

humidity, which is memorized by the signal from the output 32 of the key 33 on the recording device 2. At the same time, the converter 36 generates the output signal O through time T2, proportional to the voltage Do, i.e. the temperature of the studied medium (material). In this case, if the key 33 is set to the temperature recording mode, the counter is stopped by the counter 7, and the counter code 7 through the converter 38, to the address input of which the level O is fed from the output 39 of the key 33, is recoded into the temperature readings which are memorized by the signal from the output 32 of the key 33 on the recording device 2.

Further, the signal from the fourth output 12 of block 6 turns off the source 17. At the time specified by block 6 and necessary to bring the sensor 3 into equilibrium with the test medium (material) after the measurement, the measurement process automatically repeats.

The constant voltage source 1 is designed to power all the nodes of the circuit and supply a stabilized reference voltage to the input of the converter 36, the power supply voltage to the converter 38, the key 33 and the counter 7 being supplied only for the measurement time of the selected parameter, which allows the device to be realized with independent power supply from small-sized batteries or batteries with a voltage of 9 V, or from a small-scale voltage rectifier.

The generator 5 clock pulses is designed to issue rectangular pulses with a frequency of 10-50 kHz. The frequency of the generator is set using a quartz resonator or a capacitor with a small TKE.

The control unit 6 is designed to generate priority signals for switching on, disconnecting and resetting the main blocks and circuit elements: source 1 constant voltage, counter 7, switch 15, source 17, unit 16 and can be performed according to the scheme shown in Fig.2.

The control unit 6 comprises a timer 41, a first 42, a second 43 and a third 44 resistors, a first 45 and a second 46 capacitors, a first 47, a second 48 and a third 49 inverters, timer outputs 50 and 51, and inputs 52-55.

Block 6 works as follows.

In the initial state, at outputs 50 and 51 of timer 41 and outputs 10 and 11 of the block, the voltage level is high, and on the first 9 and fourth 12 outputs of the block it is low. Through the first 42 and second 43 resonators, the charge of the first capacitor 45 occurs up to a voltage equal to 211Pit / 3, at the same time after a time of 0.685 (Ri + R2) C, at outputs 50 and 51 of timer 41 and the second output

A block voltage appears at block 10, and a high level voltage at output 11. The first output of block 9 is a positive pulse with a duration of no more than 500 µs, depending on the capacitance of the second capacitor 46, the third resistor 44 and the response threshold of the first inverter 47, and the third output 11 of the block has a negative pulse.

Next, the first capacitor 45 starts

5 is discharged through the first resistor 42 to the voltage 1) pit / 3 and after a time of 0.685-R2 C, a high level appears at the output 50 of the timer 41 and the output 10 of the block 10, and a low level at the fourth output 12 of the block. Further, the operation of the circuit is repeated cyclically.

The counter 7 is designed to measure the duration of the pulses, depending on the humidity and temperature, by counting the frequency of the generator produced by the generator 5 during the duration of the pulse of the corresponding duration.

The switch 15 is designed to be disconnected by a signal from the block 6 of the output of the source 17 from the converter 36.

DC source 17 is designed to supply a DC pulse of 50-200 mA to sensor 3.

The code converter 38 is designed to transcode the code of counter 7 into a temperature or humidity value in order to linearize the functions p, (ri) and t, (G2) and to obtain reliable readings on the recording device 2.

0 A voltage-pulse-voltage converter 36 is designed to convert a voltage Co, proportional to the measured temperature, on sensor 3 to a pulse width and can

5 to be performed according to the scheme shown in FIG.

Converter 36 contains a capacitor 56, a resistor 57, and a comparator 58. Converter 36 operates as follows.

In the initial state, the output of the comparator 58 is a high voltage level, while the capacitor 56 is charged before the voltage. The discharge before the voltage Don

5 through resistor 57 over time

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When the voltages Uc and Don are equal, the signal O appears at the output of the comparator 58.

Sensor 3 of temperature and humidity is made in the form of a temperature-sensitive element coated with a film selective for the NaO sorbent molecules.

Comparator 4 is designed to compare voltages at the first 22 and second 23 inputs. With equal voltages, the output should be the signal O.

The key 33 is for selecting the mode of recording the information Temperature or Humidity. The mode is selected by applying to the input 40 of the converter 38 a level O or level 1, respectively, and also by connecting the output 32 of a key to one of its inputs 35 or 34, respectively. A dual toggle switch can be used as a key.

The recording device 2 is designed to record the values of temperature or humidity and can be performed on the indicator with decoders.

Resistive divider 19 is designed to divide the voltage of sensor 3 and provide temperature compensation for moisture readings. Resistive divider 19 can be made according to the scheme shown in FIG. 4.

Resistive divider 19 contains the first 59 and second 60 resistors and thermistors 61. Resistor values depend on the resistance of the sensor 3, the current applied to the sensor 3, the material of the sensor and the material used as a sorbent.

Sampling and storage unit 16 is designed to memorize the voltage from the output of DC source 17 and hold it for the duration of the humidity measurement pulse at the input of the comparator 4,

In the proposed device, besides measuring the humidity of the environment, it simultaneously measures its temperature, which expands the functionality of the device. The accuracy of the measurement is increased. This is achieved by introducing a resistive divider 19 and a block 16 into the circuit, which makes the duration of the heat pulse independent of changes in humidity with temperature. The introduction of converter 38 into the circuit allows one to linearize the curve for the dependence of the duration of the heat pulse on the humidity of the medium or material being studied and to smooth out the possible non-linearity of the instantaneous voltage drop on sensor 3, converted into a digital code, on the temperature of the medium or material under investigation.

Claims (1)

Apparatus of the Invention A device for measuring the parameters of a medium, comprising a constant voltage source, a recording instrument; A sensor made in the form of a temperature-sensitive element, a comparator, a clock pulse generator, the first to third outputs of a constant voltage source are connected respectively to the power inputs of the clock pulse generator, the first input of the control unit and the first input of the comparator, in order to expand the functional device capabilities, a counter, a switch, a sample and hold unit, a DC source, a resistive divider, a key, a code converter and a voltage converter are entered into it e is the pulse duration, the counter reset input is connected to the first output of the control unit, the second to fourth outputs of which are connected to the first input of the switch, the first input of the sampling and storage unit and the first input of the DC source, the output of which is connected to the first input of the resistive divider and the second inputs of the switch and the block of sample and storage, the output of which is connected to the second input of the comparator, the third input of which is connected to the output of the resistive divider, the second and third inputs of which Connected respectively to the first and second outputs of the sensor, the output of the clock pulse generator is connected to the counting input of the counter, the enabling input of which is connected to the recording input of the recording device and the first output of the key, the first and second inputs of which are connected respectively to the output of the comparator and the output voltage-duration converter pulse, the first input of which is connected to the output of the switch, the output of the counter is connected to the first input of the code converter, the second input and output of which are connected to the fourth output of the constant voltage source is connected to the second input of the voltage converter — the pulse duration; the input of the constant voltage source and the first input of the direct current source are interconnected; the eleventh outputs of the DC source are connected respectively to the second inputs of the control unit and the DC source, to the third inputs of the sampling and storage unit, the switch, the voltage converter en-longLU d 56 i5 $ TO Olorn. FIG. five the accuracy of the pulse and code converter and the power inputs of the counter and recording instrument. Be Haws & ЫХ30 FIG.