SU1094133A1 - Method of checking quality of piezoelectric plate surfaces - Google Patents

Abstract

METHOD OF CONTROL QUALITY OF THE SURFACE OF PIEZOELECTRIC PLATES / including the impact on the controlled plate with a variable electric signal with a frequency corresponding to the excitation of the odd mode of oscillation control plate by the difference of the informative parameters of the first and second parameters eny, characterized in that, in order to increase reliability of control, a variable frequency signal 31lektricheskrgo by repeated exposure to excitation of the corresponding selected i even Mofsibi oscillations, and in selected ampliS Tudu respective vibration modes as infor (A tive parameter.

Description

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The invention relates to the technology of special electronics and can be used in the manufacture of piezoelectric devices - quartz resonators, integrated quartz oscillators, monolithic piezoelectric filters.

A known method of controlling the quality of the surface of piezoelectric plates, which includes illumination. Dissue DIU 1X of piezoelectric plastids with ultraviolet light, select the number of interference rings fll as an informative parameter.

The disadvantage of this method is the low reliability of the control, due to the ambiguous correspondence between the number of interference rings and the electrical parameters of the studied piezoelectric

plates.

The closest to the invention is the technical essence (method of controlling the quality of the surface of piezoelectric plates, including on-controlling the plate with a variable electric signal with a frequency corresponding to the excitation of the odd mode of oscillation, the first measurement of the informative parameter, repeated exposure to the plate under control with a variable electric signal and the second measurement of the informative parameter, making a judgment about the quality of the surface of the test plate in different ways ti informative parameters of the first and second measurements, wherein as an informative parameter selected resonant vibration frequency corresponding modes z

The disadvantage of this method is the low reliability of the control, due to the inability to control the imperfections of the surface of the piezoelectric plate in the form of microcracks, micro-scratches, etc.

The purpose of the invention is to increase the reliability of control.

This goal is achieved by the fact that, according to the method of controlling the quality of the surface of piezoelectric plates, which includes the effect on a controlled plate by a variable electric signal with a frequency corresponding to the excitation of an odd mode of oscillation, the first measurement of the informative parameter.

repeated impact on the controlled plate with a variable electric signal and the second measurement of the informative parameter, drawing up

judgments about the quality of the surface of the controlled plate on the difference of the informative parameters of the parameters of the first and second measurements, the frequency of the variable electrical signal

when repeated exposure, choose the appropriate excitation of the even vibration mode, and as the informative parameter choose the vibration amplitude of the corresponding modes.

5 In FIG. 1 shows a block diagram of an apparatus for implementing the method, FIG. 2 - amplitude-frequency characteristic of the controlled plates. . The device contains electrodes 1

0 and 2, a controlled plate 3, a measuring bridge 4, an alternating voltage generator 5, a voltmeter 6, and a frequency meter 7 are placed between the turboids. The method is carried out as follows

5 way.

A piezoelectric plate 3 is placed between the superposed electrodes — the lower electrode 2, the diameter of which corresponds to the diameter of the piezoelectric plate, and the upper electrode 1, the diameter of which corresponds to the diameter of the working electrode. Through the overhead electrodes 1 and 2, the monitored plate is subjected to alternating voltage, which also comes from the generator 5 to the measuring bridge 4. The variable voltage from the measuring bridge 4 is measured with a voltmeter 6, and

 generator alternating voltage frequency 5 - frequency feo 7.

The piezoelectric plate is excited successively at frequencies f and ij corresponding to the odd (i is the working part of the plate) and even (i d - for example, second harmonic) vibration mode. The quality of the plate surface is judged by the difference in the amplitudes of the mode oscillations at frequencies -f and i.

This method provides high reliability of control due to the fact that an ideal flat piezoelectric plate with thickness shear variations is not excited on even harmonics, and the resulting nonideality of the piezoelectric plate surfaces (thickness, ruptured layer, micro scratches and microcracks) when fabricated makes incomplete compensation of the surface charge when the piezoelectric plate is excited in an even mode, the oscillator, while the amplitude excites the south signal, the more The surface of the piezoelectric plate is different from the ideal one.

In this method, polished crystalline crystals were controlled.

elements of the frequency range 20-30 MHz for the first mechanical harmonic, with an element diameter of 6 mm. The attenuation of the signal at a frequency close to the second harmonic ranged from 50 to 60 dB, depending on the quality of the surface of the elements, and the width of the frequency spectrum was also proportional to the intensity g of disturbances. surface elements.

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2

Claims (1)

SURFACE QUALITY CONTROL METHOD OF PIEZOELECTRIC PLATES, including exposure to a controlled plate with an alternating electric signal with a frequency corresponding to the excitation of an odd vibration mode, the first measurement of an informative parameter, repeated exposure to a controlled plate with an alternating electric signal and the second surface measurement with informative The controlled plate by the difference in the values of the informative parameters of the first and second measurements, about characterized in that, in order to increase the reliability of control, the frequency of the alternating electric signal upon repeated exposure is chosen to correspond to the excitation of an even mode of vibrations, and the amplitude of the oscillations of the corresponding modes is chosen as an informative parameter. fi g. 2