SU1679419A1 - Method of determination of parameters of piezoelectric converter - Google Patents

Abstract

The invention relates to technical acoustics and can be used in the manufacture and calibration of ultrasonic piezoelectric transducers. The purpose of the invention is to improve the accuracy of monitoring the parameters of a piezo transducer. The method consists in exciting a piezo transducer with a two-pole current pulse and measuring the maximum voltage of the voltage Do on the piezo transducer during the action of the excitation pulse, as well as the amplitudes Ui, U2, Ua of the first three half-waves of the voltage on the converter after the excitation pulse terminates and determining the parameters of the piezo transducer. given in the specification. Due to the use of a sinusoidal excitation pulse farm, the error caused by the duration of its front in the prototype is eliminated, and the width of the spectrum measured on the voltage converter is reduced, which allows the use of more accurate measuring instruments. 3 il. W Ё

Description

The invention relates to technical acoustics and can be used in the manufacture and calibration of ultrasonic piezoelectric transducers.

The purpose of the invention is to improve the accuracy of control parameters of the piezotransducer.

Figures 1 and 2 are graphs illustrating the proposed method; FIG. 3 is a block diagram of a device implementing the method.

A method for monitoring the parameters of a piezo transducer is as follows. From the generator of electrical signals to the piezoelectric converter serves a current pulse, having the form of one period of a sinusoid

(Fig.1 a), the duration of which is equal to the period of natural oscillations of the piezotransducer.

On the plates of the converter, a cosine voltage (current integral on the physical capacity of the converter) is formed during the current pulse duration. At the end of the input pulse, free natural oscillations of the converter continue and a sinusoidal damped voltage is induced (Fig. 1b), the amplitude of which decreases according to the law e. The maximum voltage U0 at the transducer is measured during the action of the excitation pulse and the amplitude Ui, U2. Ua the first three half-waves of its own VI VI

4 S

voltage fluctuations on the transducer, which determine the parameters of the piezoelectric transducer. The coefficient of electromechanical communication K is determined by the formula

u0 + s

(1-D).

With a small attenuation during the period of natural oscillations T0

 () where 5Т0 - attenuation for the period of natural oscillations

U124J1-U2, U32 I U2 I- U3 I.

Amendment A, which takes into account the difference between the excitation pulse and the square meander, is numerically calculated for the values of the electromechanical coupling coefficient K in the range of 0.1–0.65 and, 8 and is shown as a family of curves in FIG. Transducers with parameters that go beyond these limits are practically not encountered. It is also approximated by the expression

0.055

A Y (0.68-k) -K-fO, 01 where

to 0.017

14.43d10

The capacitance of converter C can be obtained by measuring the extreme voltage Dos for the case when the reference capacitor with capacitance Се is connected instead of the piezoelectric transducer.

  Sae Wae Sp-

The voltage of the oscillator 1 of sinusoidal oscillations (Fig. 3) is connected to the input of logic circuit 2. The latter transmits to the output single periods of the solenoid voltage to the voltage, between which there are pauses many times longer ). The cut pulse is fed to the amplifier 3 current. AT

the holder 4 includes or inserts the piezo transducer under study 5. React ,. those. the voltage on the piezoelectric transducer is monitored and measured using an oscilloscope 6.

F o rumlula and z o breetn

The method of determining the parameters of the piezotransducer, which consists in supplying a two-pole excitation current pulse with the duration of each half-wave To / 2, where T0 is the period of natural oscillations of the piezotransducer, and measuring the maximum value of the voltage UOBO for the duration of the excitation pulse, as well as

the amplitude values Ui, U2, Ua of the first three half-waves of the voltage on the piezoelectric transducer after the end of the exciting pulse, characterized in that, in order to improve the accuracy,

current pulse is sinusoidal

r T0 and TO sin coefficient at O

1o

35

The electromechanical coupling K and the attenuation coefficient b are determined by the formulas

K Utgg

Uo + Ui

(1-A);

The increase in accuracy when controlling the parameters of the piezoelectric transducer is achieved, firstly, due to the fact that when using a sinusoidal excitation pulse, there is no inherent error in the prototype caused by the finite duration of the front of the excitation pulse, secondly, the sinusoidal excitation pulse has a narrower frequency spectrum, which allows Do not use more accurate measuring equipment.

 AJ12 -.h

d) where) 2; U2-U3;

and; (

(ab8 -k) to +0,01 -aio o.oss,

v 0.017

Ix - / Yf

14.43OT ° dT0 attenuation over the period.

1

-5 §G

Oj

I4

Claims (1)

A method for determining the parameters of a piezoelectric transducer, which consists in supplying a bipolar exciting current pulse with a duration of each half of 20 To / 2, where To is the period of natural oscillations of the piezoelectric transducer, and measuring the maximum voltage Uo during the action of the exciting pulse on the piezoelectric transducer, as well as 25 amplitude values Ui, U2, U3 of the first three half-waves of voltage on the piezoelectric transducer after the end of the exciting pulse, characterized in that, in order to increase accuracy, the exciting 30, the current pulse has a sinusoidal shape i = To sin for 0 <t <To, and the coefficient of electromechanical coupling K and the attenuation coefficient ¢ 5 are determined by 35 formulas where Ui2 = Ui-U2: U32 = l U2-U31: ui = Ts £ [1 + <5To]: 45. ² Δ = Υ ^ 68-k) · R + 0.01 · dT _about 0.055 _to 0.017 _ ⁵⁰ 14.43 ^0T ° 'ATT - attenuation in the period.