SU1672337A1 - Materials property multiple measurement apparatus - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the dielectric constant and the resistance of materials. The purpose of the invention is to improve the accuracy and reliability of the measurement. The device comprises a triangular voltage generator, a high-frequency measuring generator, start-up, stop-reset generators, a sensitive element, a detecting unit, a peak detector, a comparator, an output signal conditioner, a frequency meter. 4 il.

Description

one

(21) 4454997/25 (22) 07/05/88 (46) 08/23/91. Bul №31

(71) Central Design and Technology Bureau of Instrument Engineering with pilot production

(72) B.S.Gluzman, A.E.Devgopol, B.E.Fishmen and V.M.Hilyuk (53) 551.5087 (088.8)

(56) Berliner M.A. Moisture measurement. M: Energy, 1973, pp.119-122.

Measurements in electronics. - Handbook edited by V.A. Kuznetsov. M .: Energoatomizdat, 1987, pp. 232-233.

(54) DEVICE FOR COMPLEX MEASUREMENT OF MATERIAL PROPERTIES (57) The invention relates to a measurement technique and can be used to measure the dielectric constant and the resistance of materials. The purpose of the invention is to improve the accuracy and reliability of the measurement. The device comprises a triangular voltage generator, a high-frequency measuring generator, start-up, stop-reset generators, a sensitive element, a detecting unit, a peak detector, a comparator, an output signal conditioner, a frequency meter. 4 il.

The invention relates to measurement technology and instrumentation and can be used to measure the dielectric constant and resistance of sheet materials in the pulp and paper and other industries (for example, chemical, textile, etc.).

The purpose of the invention is to improve the accuracy and reliability of measurements.

Figure 1 shows the functional diagram of the proposed device for the integrated measurement of material properties; Fig. 2 shows voltage plots characterizing the operation of blocks of the proposed device for the complex measurement of material properties: a - at the output of a triangular voltage generator; b - x at the output of the amplifier, y - at the output of the peak detector; in - at the output of the comparator; Mr. output of the generator pulse start, d - on the output (L

WITH

de pulse generator stop; E - at the output of the generator of pulses of reset; Figs. 3 and 4 show an electrical equivalent circuit for the interaction of a measurement object with a sensitive element.

A device for complex measurement of material properties comprises a triangular voltage generator 1, a high frequency measuring generator 2, a sensing element 3, a detection unit 4 comprising a detector, an amplifier 5, a divider 6, a peak detector 7, a comparator 8, a trigger pulse generator 9, a generator 10 pulse stop, the generator 11 pulse reset, the shaper 12 of the output RF signal, the meter 13 frequency.

A device for complex measurement of the properties of materials works as follows.

ABOUT

 yu so

CJ

Lch |

The high frequency measuring generator 2 generates an RF voltage, the frequency of which is determined by the voltage at the output of the triangular voltage generator 1, and the amplitude is kept constant regardless of the frequency. RF voltage is fed to the input of the sensing element 3 and to the first input of the imaging device 12 of the output RF signal. From the output of the ČE 3, a voltage depending on the frequency of the generator 2 and the parameters of the ČE 3 is fed to the input of the detector 4, where a low-frequency envelope is extracted. From the output of the detector 4, a low-frequency signal is fed through amplifier 5 to divider 6 and to one of the inputs of comparator 8. The operation of the proposed device is conveniently traced through the voltage plots shown in Fig.2. Suppose first that the voltage of the triangular voltage generator increases (a, Fig. 2). The voltage at the output of the amplifier 5 varies according to bx, Fig.2, and at the output of the peak detector 7 varies according to bu, Fig.2. When the voltages at the inputs of the comparator become equal (moment in Fig. 2), the voltage at the comparator output abruptly becomes positive (L of Fig. 2), a start pulse (r, Fig. 2) and a stop pulse (d, Fig. 2) are formed. ) and the reset pulse (b, figure 2).

A start pulse is generated by the start pulse generator 9 and starts the frequency meter 13.

A stop pulse is generated by the stop pulse generator 10 and is fed to the input of the triangular voltage generator 1 and to the first (control) input of the shaper 12 of the output RF signal, triggering it. The change in the frequency of the high-frequency measuring generator 2 stops for a time from ti to t.2, (- the duration of the stop pulse). The stop pulse is also fed to the input of the generator 11 of the reset pulses, starting it with its own cut.

A reset pulse is generated by the reset pulse generator 11 and is fed to the input of generator 1 of a triangular voltage and peak detector 7. After the arrival of the reset pulse, the frequency change of the high-frequency measuring generator 2 resumes, and the sign of this change is reversed the detector is zeroed (bu, fig. 2). After zeroing the voltage at the output of the peak detector, the voltage at the output of the comparator 8 becomes negative again, the measuring circuit returns to its original state and measures the value of the informative frequency parameter during reverse pass of the frequency response of the SE.

Decreasing the voltage of the generator 1 triangular voltage all processes

are repeated, but the frequency corresponding to the point in time (and FIG. 2) is on the other side of the frequency response of the FE (since the frequency response of the FE is now in the opposite direction).

During the full measurement cycle, determined by the triangular voltage generator 1, two frequencies TL and fn are measured, at which the values of the output signal E E reach a certain and fixed part of the maximum value.

Consider the most significant factors that determine the measurement conversion performed by the proposed device.

The sensitive element 3 can be written down following dependence of the amplitude of the output signal on the frequency:

C,

25

 + R4RH) 2 + lJ (f-) 2

. 0)

where RI and Li are equivalent values of the active resistance and inductance of the SE;

R1 is the additional resistance introduced into the circuit due to the attenuation of electromagnetic energy in the material of the measurement object;

RH is the load resistance;

fpea resonant frequency of SE;

Uo is the amplitude of the voltage supplied to the input of the SE from the output of the high frequency measuring generator.

For the value of fpea, the following relationship holds true: 1

Res Vi 1 g (2)

where Ci is the equivalent capacitance of the sensitive element taking into account the capacity introduced by the substance of the object of measurement.

Consider a measurement transform in which the informative parameters are the values of the frequencies TL and fn. At these frequencies, the amplitude of the signal reaches a predetermined part of the value of 1pc. Equation (1) for fn and fn implies the following

 W: (3)

equations:

VT + R1 + Rn) 2 + d (f, -1ЕУ) Ц)

MR. + R + fVf + UCfn

where K is the specified relative level of the signal amplitude at frequencies fn and fn (0 К

one).

Equating the expression of the left we get

LL .. „

2n

rf and rezch2 (f "- -, -) - (fn -Ј-Г from here

ry

fpes - ffl fn. (5)

Equation (5) defines the value of fpea through the values of fn and fn.

Substitute in the first equation of system (3) the value of res (ie, the value of I at) and f2pes in formula (5). Then we get:

K -

(Ri R1 + R ,.) H ("- n) 2 (Ri-R + RH)

(0)

Hence follows (Ri + R1 + RH) 2

L2 (r „- fn) 2. (7)

1 TO

Expression (7) describes the functional relationship between the values of R1 and the values of fn and fn.

Thus, it is possible to determine the properties of measurement objects by measuring the informative parameters f l and f p, taking into account dependencies (5) and (7).

Claims (1)

Invention Formula A device for complex measurement of material properties, comprising a triangular voltage generator connected in series, a high frequency measuring generator, a sensing element, a detecting unit and a frequency meter characterized in that. that, in order to increase the accuracy and reliability of the measurement, a peak detector, a comparator, a start pulse generator and a stop pulse generator, a reset pulse generator, a high frequency output driver were added, the output of the stop pulse generator to the output of the reset pulse generator , the first input of the output high-frequency signal generator and the first input of a triangular voltage generator, the output of the detection unit is connected to the first input of the comparator and ne the peak detector input, the peak detector output is connected to the second comparator input, the comparator output is connected to the start pulse generator input and the stop pulse generator input, the start pulse generator output is connected to the first input of the frequency meter, the second high frequency output signal generator 5 input connected to the output of the high-frequency measuring generator, the output of the output high-frequency signal generator connected to the second input of the frequency meter, the output of the reset pulse generator a second input coupled to a triangular voltage generator and the second input of the peak detector 01 / 8.1 Editor S.Patrusheva Order 2835