SU914975A1 - Moisture meter - Google Patents

Description

The invention relates to technical physics, namely, moisture measurement, and can be used to measure and automatically control and regulate humidity in the chemical, textile, oil, mephallurgical, mining, food and other industries.

The moisture meter is known, which contains a generator of rectangular pulses, the color of the LED, optically coupled through a cuvette with a photodetector, and Zlok registration [1].

However, this device has low accuracy.

The closest technical solution to the invention is moisture? a homer containing a square wave generator with two anti-phase outputs, an exponential modulator connected to a power source, two LEDs emitting at the measuring and reference wavelengths and optically connected via

2

A cuvette with a photopronger connected to a registration unit, made in the form of two differentiating devices, the outputs of which are connected to the inputs of the coincidence circuit and trigger ⁵ , the outputs of which are connected to the counter, the input of one differentiating device connected to the photoreceiver, and the input of another differentiating device ^{10 not} with the first G23 LED.

. A disadvantage of the known device is limited accuracy due to the non-synchronization of the beginning of the formation of the exponential voltage and storage pulses.

. The purpose of the invention is to improve accuracy.

This goal is achieved by the fact that in a device containing a power source, a square wave generator with two anti-phase outputs, an exponential modulator connected to a power source, two

e 914975 4

LEDs emitting at the measuring and reference wavelengths and optically coupled through a cuvette with a photodetector connected to a registration unit made in the form of differentiating devices, the outputs of which are connected to the inputs of the coincidence circuit and trigger, the outputs of which are connected to the counter, the input of one differentiating device is connected to the photodetector, and the input of the other differentiating device is connected to the first LED, two keys and a frequency divider are entered, with control inputs, $ keys connected antiphase outputs of the generator of rectangular pulses, and the LEDs are connected through the switches respectively to the power source and modulator exponential _m nents, the control input of which is connected to the output of the frequency divider, which is connected with its input to an output of the generator of rectangular pulses. 22

FIG. 1 shows a block diagram of the proposed device; on Fig.2 time diagrams.

The apparatus comprises a power source 1, a generator 2 square _meters pulses with two antiphase outputs, one output of which a key divider 3 frequency '(sequential counter) whose output is connected to the control input of the modulator 4 exponent, the first and second switches 5 and 6, LEDs 7 and 8, emitting at the reference and measuring wavelengths.

Scheme ⁴⁰ also denoted kont- roliruemaya medium (cuvette) 9, a photodetector 10, differentiating Arrange CTBA 11 and 12, the trigger 13 to separate inputs, a counter 14, coincidence circuit 15) which inputs corresponding governmental ⁴⁵ connected to the trigger inputs 13 and outputs differentiating devices 11 and 12, the input of one of which (11) is connected to the photodetector 10, and the input of the other (12) - with 5 ° LED 8 and the output of the key 6, the main input of which is connected to the power source 1, and the control input - with the output generator of 2 rectangular pulses, anti-phase output 55 connected to a light-emitting diode 7 and the main input - with the output of the modulator 4 exponent input

which is connected to the power source 1.

The device works as follows.

The controlled medium 9 is irradiated with two radiation fluxes _{0 0} 7 and * Φ _vg at the reference and measuring wavelengths, respectively. The radiation flux at the reference wavelength is changed exponentially. Then the flows F ^, that have passed through the cuvette. and F _g from both emitters are

*

4 ^with e

χ f. o “hl · 2.

og * ^e

where t ₄ , t ₂ - the mass of the substance and moisture, respectively;

k ₄ , k ₂ are the absorption coefficients at the reference and measured wavelengths.

At the moment of equality of these flows, we obtain

£

. "7 -" "and"

where it follows ^ what

one

“Ι, * —— ~

where C _c is the time corresponding to the ~ moment of comparison;

4 is the time constant of the exponent.

The generator 2 rectangular pulses (Fig, 1) produces pulses with the required repetition frequency. These pulses from the antiphase outputs are fed to the input of divider 3 frequencies and to the control inputs of the keys 5 and 6. The input of the modulator 4 of the exponent and the key 5 simultaneously receive the pulse of the formation of the exponent and filling pulses. At the output of the key 5, a discrete exponential current pulse is formed, which, flowing through the LED 7 ”, causes a radiation flux in accordance with such a law.

An out-of-phase impulse filling ^ the switch 6 switches. A current pulse flowing through the LED 8 causes a luminous flux whose amplitude is constant. The flows that have passed through the cuvette 9 are perceived by the photodetector 10. FIG. 2a shows a temporary diag ⁵ 9!

total photoelectric signal frame at the photodetector output. This signal is fed to the input of the first differentiator. The signal (Fig. 26}) is then fed to one of the 5 inputs of the trigger 13. To the other input of the trigger 13, a signal is output from the second differentiator 12 £ of Fig. 2 c) The trigger starts to trigger from alternate pulses ^{, 0} from the outputs of the first and second differentiators devices until the phase of the photoelectric signal changes. Up to this point, 15 series of pulses is being input to the counter. After a phase change on the trigger input 13 pulses arrive simultaneously ((2 g) and ceases to operate the trigger. The output of circuit 15 appears coincidence pulse 20 '· ο6ροο3 ^Η, and a counter prepared for the next cycle. This process is repeated. As can be determined meter reading humidity value. ²⁵

The present invention improves the accuracy of determining the moisture content of samples.

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Claims (1)

Claim A moisture meter containing a power source, a rectangular pulse generator. With two antiphase outputs, 35 turns, an exponential modulator ’, под under5 6 Connected to the power supply, two LEDs emitting at the measuring and reference wavelengths and optically connected through a cuvette to a photodetector, connected to a registration unit, made in the form of two differentiating devices, the outputs of which are connected to the inputs of the coincidence circuit and the trigger, the outputs of which are connected to the counter The input of one differentiating device is connected to the photodetector, and the input of the other differentiating device is connected to the first LED, characterized in that, in order to improve the accuracy, Two keys and a frequency divider are entered into it, and the control inputs of the keys are connected to the gas-mask outputs of the rectangular pulse generator, and the LEDs are connected via keys to the power supply and an exponential modulator, the control input of which is connected to the output of the frequency divider, which is connected from the outputs of the generator of rectangular pulses.