SU1567953A1 - Digital meter of moisture content - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the moisture content of gases and various bulk materials. The purpose of the invention is to improve the accuracy in measuring the humidity of various materials. The digital moisture meter contains a measuring generator with a capacitive humidity sensor, a reference frequency generator, two counters, an indicator, two single vibrators, a delay element, a measurement mode setting unit, a reprogrammable read-only memory. The purpose of the invention is achieved by individually setting the pulse counting interval of the measuring generator. 1 il.

Description

The invention relates to a measuring technique and can be used to measure the moisture content of gases and various bulk materials in the food and light industries.

The purpose of the invention is to improve the accuracy in measuring the humidity of various materials.

The drawing shows a diagram of the proposed meter.

The meter contains an RF humidity sensor 1 consisting of functional 2 and compensation 3 autogenerators, counter 4 with a preset code, forming the address code A of a reprogrammable permanent memory device (PROM), counter 5 forming the counting interval with a preset code (signal U,) , code setting unit 6 of measurement mode, one-oscillators 7 and 8, performing the functions of the elements of the leading and trailing edges of the counting interval, elements

9 and 10-delays, programmable read-only memory (PROM) 11, register 12, output buses 13, decoder 14, and digital indicator 15.

The frequency f of oscillator 2 depends on the measured humidity B, and the destabilizing factors D0 have the same effect on oscillators 2 and 3. When counting frequency pulses Ј / in counter 4, factors D0 influence the frequencies f and f2 because the reference frequency 4 of the compensation generator 3, the interval tM of the frequency measurement f is formed

(one)

one

t NIsi fj

where N4 is the value of the code entered in subtractive counter 5 by the signal U,

(/

sd

OE

h

coke

00

The value of the NA code generated at the outputs of counter 4 by the end of the interval

t ,, (signal 11Л), is determined by the formula

(N

about + t ,,

 - 2

(2)

where n is the number of binary bits of the counter 4.

The value of the Nc code is chosen by the condition

 - tn- Ј, MEI, (3) where the minimum value of the functional frequency Ј) ,.

The N ft code generated by the counter 4 is fed to the address inputs (PROM) 11, from which the binary U-code N & n is extracted by the signal U generated by the one-shot 8 at the end of the interval tM. humidity. The Ne code from the outputs (EPROM) 11 is applied to the digital inputs of register 12 and entered into this register by the signal l formed by the element 9 from the signal U3. The outputs of the register 12 are connected to the output buses 13 and the inputs of the decoder 14, which converts the binary to The current code is N6 in indicator code 15. Indicator 15 provides a continuous indication of the measured humidity value until the end of the next measurement cycle.

The meter is restarted by the signal generated by the delay element 10.

The duration of the interval tM is chosen by the condition

tB

one

5min yv

(four)

Where

- minimum coefficient

 bmin ov

The humidity conversion factor 2 to the frequency change fj, & B is the required discreteness of the digital humidity reading.

The code sensor 6 of the intention mode is inserted into the meter to enable measurement of the moisture content of various materials (both gases and various particulate matter). Depending on the physical composition and particle size of the substance, the coefficient of conversion of moisture into frequency varies and therefore for each type of substance it is advisable to have in the PROM 11 its own array of N6 code values and to provide its own frequency measurement interval tM according to formula (4). 6 has as many states as different types of

substances are supposed to be measured, and for each substance at the outputs of the setter 6, its own values of the codes NO and N.

In this case, the number of states of the counter 4 and the number of cells (EPROM) 11 must

be no less than

km. S i§i.ia.L (

  fl7А В

1Ј “L

(five)

where K is the number of setpoint states 6; ®4 max fwwiT maximum and minimum measured humidity for i-th substance;

& B is the discreteness of the digital reading of the humidity of the 1st substance;

,, S el max,

To coefficient of nonlinear min

characteristics of the RF humidity sensor.

For example, with B; vaKC 99.0%,

 1 (W. LV; 0.1%, KN; 1.25 and K 8 we have:

N 7 9A0G10A0 1A25

0.1

Claims (1)

Invention Formula A digital moisture meter containing a measurement generator with a capacitive humidity sensor, a reference frequency generator, first and second counters, and a digital indicator, characterized in that, in order to improve accuracy when measuring the humidity of various materials, a reprogrammable read-only memory (PROM) is inserted into it , the code unit of the measurement mode, two one-shot and the delay element, the first and second counters are connected to the outputs of the code unit of the measurement mode, the outputs of the first counter under Connected to the address inputs of the EPROM, the zero code output of the second counter is connected to the one-shot inputs and the first counter count input, the first one-channel output is connected to the first counter preset input, the second one-channel output is connected to the read information input from the ROM and to the input of the delay element, output which is connected to the preset input of the second counter ka. Kodfi / A AfiL H Humidity Substance C and C 7 J + -Idu / about J V5