WO2009057535A1

WO2009057535A1 - Method for inspecting electromechanical characteristic of electromechanical conversion element

Info

Publication number: WO2009057535A1
Application number: PCT/JP2008/069399
Authority: WO
Inventors: Makoto Tani
Original assignee: Ngk Insulators, Ltd.
Priority date: 2007-10-30
Filing date: 2008-10-21
Publication date: 2009-05-07
Also published as: JPWO2009057535A1; JP5225284B2

Abstract

Provided is a method for inspecting electromechanical characteristic of an electromechanical conversion element which measures frequency characteristic data on AC admittance of an electromechanical conversion element such as a piezoelectric element and acquires “a maximum electric characteristic value Amax at the element resonance frequency (such as a peak value Gmax of AC conductance G, a difference between a maximum value Bmax of AC susceptance B and a minimum value Bmin, and a diameter 1/R1 of AC admittance circle)” and “a resonance sharpness Q”. “The obtained peak value Amax of the electric characteristic value” is divided by “the obtained resonance sharpness Q” to obtain a value (Amax/Q) which is used for inspecting the electromechanical characteristic of the electromechanical conversion element.

Description

Electromechanical characteristics inspection method for electromechanical transducers

The present invention is a piezoelectric or electrostrictive actuator, super-standing

Electromechanical transducers such as piezoelectric elements and electrostrictive elements that are used in electromechanical transducers such as sine wave motors and piezoelectric lances and that generate mechanical distortion when a voltage waveform is applied. The present invention relates to an electromechanical property inspection method for inspecting the quality of the electromechanical property. Background technology

In addition, an electromechanical transducer element used in an electromechanical transducer such as a piezoelectric or electrostrictive actuator, an ultrasonic motor, and a piezoelectric transformer, which generates mechanical vibration when a voltage waveform is applied. An electromechanical transducer such as an element and an electrostrictive element (hereinafter simply referred to as “element J”) preferably has a large cross G admittance at the electromechanical resonance frequency of the element.

For example, Japanese Laid-Open Patent Publication No. 2000-0 4 6 9 4 3 discloses a vibrator for an ultrasonic motor. This vibrating body is a vibrating body in which a substantially rectangular flat plate-like metal plate and a substantially rectangular flat plate-like piezoelectric element are bonded together, and its longitudinal vibration and bending vibration are used. Japanese Laid-Open Patent Publication No. 20 0 4 — 2 6 6 9 4 3 discloses that a frequency range in which the AC impedance becomes smaller than a predetermined value by adjusting the vertical / horizontal dimension ratio of the vibrator. It is disclosed that a wide range of "" is provided and "super-standing" is provided.

AC impedance dance is the inverse of AC admittance. Therefore

A small AC impedance is synonymous with a large AC admittance. Therefore, in general, whether or not the electromechanical characteristics of such an electromechanical transducer element are good or bad is measured by measuring the AC amplitude in the frequency range including the resonance frequency of the element. In addition, as an index value for determining the quality of the electromechanical characteristics, the AC code at the resonance frequency,,, and the conductance, and the AC impedance, which is the reciprocal thereof, and the AC To K, AC conductance that is the real part of the conductance, etc. Is used.

For example, Japanese Laid-Open Patent Publication No. 2 0 3 — 1 6 8 8 3 2 discloses a method for detecting a piezoelectric balance in which an input electrode and an output electrode are arranged on a rectangular plate-shaped piezoelectric element. In this inspection method, the AC conductance at the resonance frequency of the piezoelectric element is measured in order to estimate the temperature rise when the piezoelectric transformer is continuously driven.

In addition, EMAS-6100 “Electrical Testing Method for Piezoelectric Ceramic Vibrators” is a standard for measuring the electromechanical characteristics of piezoelectric elements. The frequency characteristics of the admittance are measured, and the electrical equivalent circuit constants (C 0, C l, R l, L 1) of the vibrator and the vibration of the vibrator are measured based on the frequency characteristic data obtained by the measurement. A method for calculating the sharpness Q is disclosed.

In addition, Japanese Patent Laid-Open No. 10-1 1566 48 discloses an AC add and a balance circle by a least square method to obtain a piezoelectric vibrator such as a crystal vibrator. Discloses a method for accurately calculating equivalent circuit constants.

These conventional inspection methods are suitable for electromechanical transducers such as piezoelectric or electrostriction actuators, super-stand-wave sensors, and piezoelectric transformers.

It is suitable for inspecting the electromechanical characteristics of the electromechanical transducer element incorporated in an electromechanical transducer. However, in the inspection of the electromechanical characteristics of the electromechanical conversion element alone before being incorporated into the electromechanical conversion equipment, there is a problem that the quality of the electromechanical characteristics cannot be judged properly.

More specifically, in the conventional inspection method, the measured value of the electromechanical characteristic value of a single element fluctuates relatively large from measurement to measurement. In addition, the measured value of the mechanical property value of the device changes relatively greatly before and after the device is incorporated into the electromechanical conversion device. In other words, the correspondence between the measured value of the electromechanical characteristic value in the single element and the characteristic of the electromechanical conversion device after the element is incorporated is not good.

For this reason, if the conventional characteristic inspection method is used, an element having a poor vibration characteristic (characteristic defective element) cannot be determined as “defective”, and the characteristic defective element is directly assembled in the electromechanical conversion device. In some cases, defective characteristics were found only after the characteristics of the electromechanical conversion device were assembled. As a result, the manufacturing cost of electromechanical conversion equipment increases. There was a problem.

Furthermore, such a problem arises in the characteristic inspection of an electromechanical transducer element in which an electrode (electrode terminal) is arranged on the surface of the element, when an electric measurement probe is brought into contact with the electrode arranged on the element surface. In particular, it was found that the phenomenon occurred particularly markedly.

Here, after the electromechanical conversion element is incorporated in the fc '5¾ mechanical conversion device, it is driven to vibrate at the resonance frequency (or a frequency near the resonance frequency) of the electromechanical conversion element. However, the electromechanical conversion element is used as an element (quasi-statically driven element) that brings about a substantially static displacement after being incorporated in the electromechanical conversion device. . In other words, the electromechanical conversion element is applied with a voltage waveform that changes over a period of time much longer than the resonance period, and is used as an element for causing mechanical displacement at that time.

> ·

Japanese Laid-Open Patent Publication No. 2 0 0 6 — 3 4 3 2 2 2 discloses a method for inspecting the electromechanical characteristic (displacement characteristic) of such a quasi-statically driven electromechanical transducer. . Specifically, it is disclosed in Japanese Patent Application Laid-Open No. 2000-063 1 3 4 3 2 2

The electromechanical conversion element disclosed in No. 2 is a piezoelectric element that is used as an actuator while being bonded to a support member. According to the disclosed inspection method, it is in a single state (the state of the heel bonded to the support member)

Based on the knowledge that a predetermined voltage is applied to the piezoelectric element at (1) and the amount of charge q accumulated in the piezoelectric element is measured, and that the amount of charge q has a predetermined correlation with the displacement amount, Based on the measured charge q, the displacement characteristics (piezoelectric characteristics) of the piezoelectric element are estimated.

Further, International Publication No. WO 2 0 0 5/1 0 4 2 5 8 discloses a frequency characteristic when a piezoelectric / electrostrictive actuator is driven, and the “resonance frequency, It is disclosed that “the displacement amount of the piezoelectric Z electrostriction actuator” is estimated on the basis of the magnitude of the peak value of the resonance waveform and the surface area of the resonance waveform.

However, according to the inventor's investigation, the accuracy of the displacement amount (displacement characteristic) estimated by the conventional technique is not sufficiently high. Therefore, when the conventional characteristic inspection method is used, an element having a poor displacement characteristic is used. (Characteristic failure element) was found to be “not good”.

Furthermore, a method is known in which the amount of displacement of the electromechanical transducer is precisely measured by an “optical device such as a laser displacement meter”. However, Since this method requires a long time for measurement, it is not appropriate as an inspection method when mass-producing electromechanical transducers.

As described above, the conventional inspection method has not only the electromechanical characteristics of “electromechanical transducers used in a mode of being vibrated at a resonance frequency” but also “electromechanical transducers used quasi-statically”. Electromechanical properties, and

It is not appropriate as a method for evaluating the electromechanical characteristics of the “electromechanical transducer element used in a mode in which it is vibrated at a frequency different from the resonance frequency”. Disclosure of invention

The present invention has been made in order to cope with such problems in the prior art, and includes the present invention, an ultrasonic motor, a lance liquid ejecting apparatus, and a switch. Electromechanical transducers such as Γ piezoelectric elements and electrostrictive elements that are displaced by a voltage that has a predetermined waveform and is applied with a voltage that has a predetermined waveform. Provide an inspection method (electro-mechanical mechanical characteristic inspection method for electromechanical transducers) that can determine the quality of mechanical characteristics (vibration characteristics or displacement characteristics) efficiently and with high precision. Learn as one purpose

As a result of intensive investigation into the cause of the above problem, the present inventor found that the inventor found that the electromechanical transducer is an element that is used in a state where it is vibrated at a vibration frequency. Mechanical converter The characteristic value of the unit's built-in electromechanical transducer element is not “repetitive measurement repeatability”. The holding state when holding the element with a jig or the like during characteristic inspection

· I noticed that it was caused by-variation. More specifically, since the electromechanical transducer element vibrates as a whole, the jig for holding the fiber during characteristic inspection inhibits the vibration of the element as much as possible. O When using a non-structure, the part holding the element is slightly deviated from the planned part or the element holding force is slightly different from the planned force (strength) As a result, the degree to which the jig blocks the vibration of the element changes. As a result, it is considered that variations occur in measured values of element characteristics.

Furthermore, the present inventor makes the electrical measurement probe in the case where the electrical measurement probe is brought into contact with the electrode arranged on the electromechanical conversion element to perform the characteristic inspection. Since this also affects the vibration of the electromechanical transducer, we thought that the variation in measured values of the characteristic inspection would be even more pronounced.

In addition, the present inventor has a good correspondence relationship between the characteristic inspection measurement value of the electromechanical conversion element alone before being incorporated into the electromechanical conversion apparatus and the various characteristics of the electromechanical conversion apparatus after incorporating the element. The reason for this was thought to be that the element holding state at the time of the characteristic inspection of the element alone was different from the element holding state after being incorporated into the electromechanical conversion device.

While investigating how the variation in the holding state when holding the electromechanical transducer with a jig or the like affects the characteristic inspection measurement value of the electromechanical transducer, The following knowledge was obtained by repeating the process of attaching the element to the jig and measuring the AC address, and the inductance.

(1) Peak value (maximum value)

) Y max and resonance sharpness Q (Q value) vary relatively from measurement to measurement.

(2) However, the two (peak value Y max and resonance sharpness Q) are in a substantially constant proportional relationship. In other words, when k is a proportional constant, the relationship Y max = k · Q is substantially established between multiple measurements.

Furthermore, the present inventor measured the frequency characteristics of AC element and S pattern of a single element for several elements, and also measured the vibration displacement of the element and the ultrasonic motor incorporating the element. I measured the rotational speed. As a result, for example, an element with a large proportional coefficient k = Y max, Q between the peak value Y max of AC admittance and the resonance sharpness Q has a large vibration displacement and rotational speed. I understood. Based on the above, the present inventor found that the peak value Y max and the resonance sharpness Q of the AC admittance change depending on the holding state of the element during the characteristic inspection, but the proportional coefficient k = Y max / Q is unique to each element: k is the electromechanical conversion characteristic of Γ ”. In addition, the inventor has not obtained the AC admittance max, but the AC conductance peak value and the peak value of the dance phase, etc., and obtained based on the AC add 1 wave number characteristic measurement result. “Resonance frequency: Target characteristic value A max (characteristic maximum value A m _ax , Special 'I: Q value (k = A max / Q) is also the value for each element. We obtained the knowledge that the “electromechanical conversion characteristics of the element” can be expressed appropriately regardless of the holding state.

Furthermore, the inventor makes the case where the electromechanical conversion element is an element used to cause a quasi-static displacement, and the electromechanical conversion element is vibrated at a frequency different from the resonance frequency. `` The amount of displacement DJ when a predetermined voltage is applied to these elements and the value obtained by dividing the electrical characteristic value A max that is maximum at the resonance frequency of those elements by the Q value '' (K = A max / Q) ”, we have found that there is a very good correlation.

The inspection method according to the present invention based on such knowledge is “applied to an electromechanical conversion device” and “a voltage (voltage waveform) having a predetermined waveform (at least a pair of) electrodes is applied. This is a method for detecting an electromechanical characteristic of an electromechanical transducer, which includes the following steps.

(1) a first step (element holding step) for holding the electromechanical transducer by a holding jig;

(2) The electrode of the electromechanical conversion element is electrically connected to an AC permeance measuring device, and “in the frequency range J including the resonance frequency of the electromechanical conversion element, the AC admittance between the electrodes”. 2nd step to measure AC admittance frequency characteristic data representing frequency characteristics of

(AC admittance frequency characteristics measurement step),

(3) The peak value of the electrical characteristic value (maximum characteristic value) A max and the resonance sharpness Q, which is the maximum at the resonance frequency, based on the AC Amami V-tance frequency characteristic data measured in the second step. 3rd step to acquire (data analysis step),

(4) The value A max / Q (that is, the peak value A max of the electrical characteristic value obtained in the third step divided by the resonance sharpness Q obtained in the third step) And a fourth step (a verification step) in which an electromechanical characteristic inspection of the electromechanical transducer element is performed using the proportional coefficient k).

Note that “use value A max Z Q” in step 4 naturally includes “use value Q / A max J.” Also, in step 1

“Holding” includes placing an electromechanical transducer on the top of a base or the like.

According to this characteristic inspection method, it is unique to each element and varies from measurement to measurement. The electromechanical characteristics of the electromechanical transducer are inspected based on the “value A maxZ Q”, which has a small deviation. Therefore, it is possible to determine whether the electromechanical characteristics (vibration characteristics or displacement characteristics) of the electromechanical conversion element are good and accurate with high repeatability. Furthermore, the value A max / Q is a “measured value of the electromechanical characteristics unique to the element” that shows a good correspondence with the electromechanical conversion characteristics of the electromechanical conversion device after the element is assembled. Before assembling the element into the electromechanical conversion device, it is possible to accurately inspect the electromechanical characteristics when the element is incorporated into the device.

In the present invention, it is desirable that “the resonance frequency when measuring the AC admittance characteristics in the second step” is selected as described below.

In general, an electromechanical transducer has a plurality of resonance modes.In other words, an electromechanical transducer has a plurality of resonance frequencies ^ and vibrates at a resonance frequency. It vibrates in a different vibration form from the vibrating field. Therefore, it is desirable that the resonance frequency is selected as follows according to the wave number used after the electromechanical conversion element is incorporated into the electromechanical conversion device.

(a) The field of an element driven at a resonance frequency (referred to as “drive resonance frequency” for convenience) after being incorporated in an electromechanical conversion device.

a 共振 It is preferable that the resonance frequency at the time of measuring the above-mentioned AC ADD and MUT characteristics is the drive resonance frequency.

(b) In the case of an element driven at a frequency different from the resonance frequency after being incorporated into a lightning mechanical conversion device, the resonance frequency when measuring the above AC impedance characteristics is `` the vibration form is similar The resonance frequency of the resonance mode (that is, the resonance frequency closest to the drive frequency when the electromechanical transducer is actually used) is preferred.

(c) In the case of an element that is driven quasi-statically after being incorporated in an electromechanical converter, the resonance frequency when measuring the above-mentioned AC admittance characteristics is the resonance mode with a similar Γ vibration form. Resonance frequency (i.e., the resonance frequency closest to the drive frequency when the electromechanical transducer is actually used)

) J is preferred. In this case, in general, the vibration form at the lowest vibration frequency is most similar to the vibration form at the time of quasi-static drive.

On the other hand, as described above, the AC admittance frequency characteristic data “Electrical characteristic value” obtained based on this includes “AC admittance J, 交流 AC inductance”, “AC impedance phase”, etc.- When the peak value of the inductance is used as “the maximum electrical characteristic value at the resonance frequency (maximum value of the electrical characteristic value) A max”, the value A max ZQ and the element are converted to electromechanical conversion. Correspondence between the characteristics of the equipment after it is installed in the equipment and is very good. Therefore,

¾ flow conductance is particularly preferred as the electrical characteristic value, i.e., the peak value A max of the electrical characteristic value adopts the peak value G max of the AC conductance. This is particularly preferred.

When the peak value G max of the AC conductance is used as the `` maximum electrical characteristic value at the resonance frequency '', the peak value G max of the AC conductance is rounded to the AC admittance circle. It is preferable to obtain the diameter 1 / R 1 by calculating it. This is because “repetitive measurement reproducibility” is further improved.

The electromechanical conversion element to which the electromechanical characteristic inspection method of the present invention is applied may be an element that generates a mechanical change ■ U ¾ ”when a voltage having a predetermined waveform is applied < The principle of generating the mechanical displacement is not limited

Examples of electromechanical transducer elements such as 0 can include piezoelectric elements, electrostrictive elements, magnetostrictive elements, and the like. The electromechanical conversion element is a single plate type, a laminated type, or a piezoelectric film formed on a substrate, and a device that functions as a child (a bimorph type actuator has a diaphragm structure, etc.) It may be.

On the other hand, the electromechanical conversion characteristics of the electromechanical conversion element can be obtained by measuring the vibration displacement frequency characteristics of the element instead of the AC admittance frequency characteristics. Furthermore, the present inventor also determines whether or not the vibration displacement frequency characteristic of the electromechanical transducer element is good or bad, as in the case of the good or bad judgment of the AC admittance frequency characteristic. using the value D max / Q _D divided by Q _D as an evaluation index value for quality determination of the elements, without having to go affected holding state of the device during measurement, accurately quality determination element I have learned that I can do it.

Therefore, the present invention provides

“Applies to electromechanical converters and has a predetermined waveform (eg A method for inspecting electromechanical characteristics of an electromechanical transducer J that generates mechanical displacement (for example, mechanical vibration) by applying a voltage having a vibration waveform) via an electrode,

A fifth strap for holding the electromechanical transducer by a holding jig.

(Holding step) and

In the frequency range including the resonance frequency of the electromechanical transducer, the electrode of the electromechanical transducer is electrically connected to a frequency characteristic measuring instrument. —,. 6th step (vibration displacement characteristic measurement step) to measure displacement frequency characteristic data,

Based on the vibration displacement frequency characteristic data measured in the sixth step, the seventh step (data analysis step) for obtaining the peak value D max of the vibration displacement amplitude and the resonance sharpness Q _D that are maximum at the resonance frequency. And)

Using the value D max / Q _D obtained by dividing the peak value D max of the amplitude obtained in the seventh step by the resonance sharpness Q _D obtained in the seventh step, the electromechanical conversion is performed. An eighth step (inspection step) to perform electromechanical property inspection of the element;

An electromechanical property inspection method including the above is provided.

Note that “use value D max / Q _D ” in the eighth step naturally includes “use value Q _D / D maxj”.

This inspection method can also determine the quality of the electromechanical characteristics of the element with high accuracy and high repeatability. A simple explanation of the drawing

FIG. 1 is a four-side view showing an example of an electromechanical transducer to which an electromechanical characteristic inspection method according to the present invention is applied. (A) is a plan view (top view), and (B) is a front view thereof. (C) is the back view and (D) is the side view.

FIG. 2 is a perspective view showing a laminated structure of the electromechanical transducer shown in FIG.

Fig. 3 is a trihedral view showing the first example of the holding jig for the electromechanical transducer shown in Fig. 1, where (A) is a plan view (top view) and (B) is a front view thereof. (C) is a side view of the holding jig in a state in which the connecting portion is removed. Fig. 4 is a trihedral view showing a second example of the holding jig for the electromechanical transducer shown in Fig. 1. (A) is a plan view (top view), and (B) is a front view thereof. (C) is a side view of the holding jig in a state in which the connecting portion is removed.

FIG. 5 is a flowchart showing the flow of the electromechanical characteristic inspection method for an electromechanical transducer according to the present invention.

Fig. 6 is a graph showing the measurement results of the frequency characteristics of the ado and mitance for the electromechanical transducer (first ele- ment). (A) shows the ad, and the frequency with respect to the frequency. This is a plotted graph, and (B) is a graph plotting the phase of the gain with respect to the frequency.

Fig. 7 is a graph showing the results of frequency characteristics measurement of the ado and the inductance for the electromechanical transducer (first element). (A) plots the inductance with respect to the frequency. (B) is a graph plotting susceptance versus frequency, and (C) is a graph plotting conductance and susceptance on the horizontal and vertical axes, respectively. Is

Fig. 8 is a graph showing the measurement results of the frequency characteristics of the electromechanical transducer (second element). (A) plots the ad, ァ, and V stance against the frequency. (B) is a graph plotting the phases of K,, and T for three wave numbers.

Fig. 9 is a graph showing the results of measurement of the harmonic frequency characteristics of the ADD and MIT terminals for the electromechanical transducer (second element). (A) plots the inductance with respect to the frequency. (B) is a graph with susceptance plotted against frequency, and (C) is plotted with conductance and susceptance on the horizontal and vertical axes, respectively. □

FIG. 10 is an electrical equivalent circuit diagram of the electromechanical transducer (first element).

Fig. 11 is an electrical equivalent circuit diagram of the electromechanical transducer (second element).

Fig. 12 is a block diagram showing an example of a measurement system for frequency characteristics of vibration displacement of an electromechanical transducer.

FIG. 13 is a schematic diagram showing an example of a method for measuring the frequency characteristics of the vibration displacement of the electromechanical transducer. Fig. 14 is a graph showing an example of the frequency characteristics measurement result of vibration displacement for an electromechanical transducer. (A) is a graph plotting displacement (amplitude) against frequency. , (B) is a graph plotting the phase of displacement against frequency.

Fig. 15 is a graph showing an example of the measurement results of frequency characteristics of vibration displacement for electromechanical transducers. (A) and (B) are shown in Fig. 14 (A) and (B). (C) is a graph plotting the “cosine component of vibration displacement” and “sine component of vibration displacement” converted based on the measured data for frequency f. The graph plots the “component” and “sine component of vibration displacement” on the horizontal and vertical axes, respectively.

FIG. 16 is a front view of the ultrasonic motor showing an example of the ultrasonic motor to which the electromechanical transducer shown in FIG. 1 is applied.

Figure 17 shows an example of a correlation plot between the resonance intensity of the admittance of the electromechanical transducer and each characteristic peak value. (A) shows the resonance sharpness and the peak of admittance. (B) is the peak value of resonance sharpness and conductance, (C) is the maximum / minimum difference between resonance sharpness and susceptance, (D) is the resonance sharpness and diameter of the admittance circle, This is a plotted graph.

Fig. 18 shows an example of a correlation plot between each characteristic peak value of the admittance of the electromechanical transducer and the square of the measured displacement characteristic. (A) shows the peak value of the conductance and (B) is the square of the admittance circle and the square of the measured displacement characteristics, (C) is the conductance peak value divided by the resonance sharpness and the measured displacement characteristics. (D) is a graph plotting the value obtained by dividing the diameter of the admittance circle by the resonance sharpness and the square of the measured displacement characteristics.

Figure 19 shows an example of a correlation plot between the measured admittance characteristics of an electromechanical transducer and the rotational speed characteristics of an ultrasonic motor. (A) is the conductance peak value and rotation speed. (B) is the diameter of the admittance circle and the square of the rotational speed, (C) is the value obtained by dividing the conductance peak value by the resonance sharpness and the square of the rotational speed, ( D) is a graph plotting the value obtained by dividing the diameter of the admittance circle by the resonance sharpness and the square of the rotational speed.

FIG. 20 shows another example to which the electromechanical property inspection method according to the present invention is applied. FIG. 3 is a three-plane view showing an example of an aeration machine conversion element, in which (A) is a plan view (top view), (B) is a front view thereof, and (C) is a side view thereof.

FIG. 21 is a perspective view showing the laminated structure of the electromechanical transducer shown in FIG.

Fig. 22 is a four-sided view showing an example of the holding jig for the electromechanical transducer shown in Fig. 20. (A) is a plan view (top view), and (B) is a front view thereof. , (C) is a rear view thereof, and (D) is a side view of the holding jig in a state in which a connecting portion is removed.

FIG. 23 is a schematic diagram showing an example of a method for measuring the displacement (quasi-static displacement characteristic data) of the electromechanical transducer shown in FIG.

Fig. 24 is a block diagram showing an example of a measurement system for measuring the displacement (quasi-static displacement characteristic data) of the electromechanical transducer shown in Fig. 20.

(A) in Fig. 25 is a graph showing the relationship between the Γ-ad and diameter of the electromechanical transducer element shown in Fig. 20 and the square of the displacement amount. (B) in Fig. 25 is the value obtained by dividing the diameter of the circle of the electro-mechanical circle by the resonance sharpness of the electromechanical transducer shown in Fig. 20 and 2 of the Γ displacement. This graph plots the relationship with the multiplier J.

FIG. 26 is a perspective view of “another electromechanical transducer” in a state where the support portion and the vibration portion are separated.

Fig. 27 is a cross-sectional view of the electromechanical conversion element cut along the plane along line 1-1 in Fig. 26.

Figure 28 is a cross-sectional view of the electromechanical converter and the child cut along the plane 2–2 shown in Figure 26.

Fig. 29 shows the holding jig and its holding jig used when measuring the "alternating current frequency, mitten frequency characteristic data" of the electromechanical transducer shown in Figs. 26 to 28. FIG. 6 is a diagram showing a state in which the electromechanical conversion element is not held by.

Fig. 30 shows the holding jig used to measure the "quasi-static displacement characteristics data" of the electromechanical transducer shown in Figs. 26 to 28, and the electromechanical conversion by the holding jig. It is the figure which showed the holding | maintenance state of an element.

Fig. 31 shows the drive voltage applied to the electromechanical transducer and the measured displacement when measuring the quasi-static displacement characteristics data of the electromechanical transducer shown in Figs. 26 to 28. It is the time chart shown. (A) in Fig. 3 2 represents the addition of the electromechanical transducer elements shown in Figs. 26 to 28,

3 is a graph showing the relationship between the diameter of the circle of circles and the square of the displacement amount. (B) in Fig. 3 2 is the "ad" of the electromechanical transducer shown in Figs. 26 to 28. This is a graph showing the relationship between the value obtained by dividing the diameter of the missance circle by the resonance sharpness and the displacement amount. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not construed as being limited to these embodiments, and various changes, modifications, and improvements can be made based on the knowledge of those skilled in the art without departing from the scope of the present invention. It is.

The electromechanical property inspection method according to the present invention can be applied to electromechanical transducers of various designs. In the electromechanical characteristic inspection method according to the present invention, in particular, an electric electrode (electrode terminal) that contacts an electric measurement probe (for example, a needle-like measurement terminal) at the time of measuring the electromechanical characteristic is disposed on the element surface. When applied to mechanical transducers, it has 58 more remarkable effects.

. The electromechanical transducer 10 shown in FIG. 1 and FIG. 2 is an example of such an electromechanical transducer element. FIG. 1 is a four-sided view showing the external appearance of the electromechanical transducer 10, and FIG. 2 is an exploded perspective view showing the shell structure of the electromechanical transducer 10.

The electromechanical transducer 1 0 has two types of internal electrodes 1 4 a and 1

This is a multilayer piezoelectric element formed by laminating a plurality of layered piezoelectric bodies 10 a sandwiched between 4 b. The upper electrode (electrode) 1 1 a and 1 1 are on the top surface of the element 10, the side electrodes 1 2 a and 1 2 b are on the side surface, and the lower electrodes 1 3 a and 1 3 b are on the bottom surface. The formed upper electrode 11a, inner electrode 14a and lower electrode 13a are electrically connected to each other by a side electrode 12a. The upper electrode 1 1 b and the inner electrode 14 b and the lower electrode 13 b are electrically connected to each other by the side electrode 12 b.

When a voltage is applied between the upper electrode 1 1 a and the upper electrode 1 1 b, the element 10 extends in the thickness direction (height H direction) by the inverse piezoelectric effect, and the length direction (L direction and The machine deforms to shrink in the (W direction).

The frequency characteristics of the AC,,, and V impedances between the upper electrode 1 1 a and the upper electrode 1 1 Measures the electromechanical characteristic values such as resonance frequency and resonance sharpness (Q value), AC conductance G, and AC sustainability B in the length direction and thickness direction. can do.

In the electromechanical property inspection method according to the present invention, holding jigs of various designs can be used. However, holding the electromechanical conversion element affects the vibration state of the electromechanical conversion element. Therefore, in order to reduce the influence on the vibration state, a holding jig with less contact with the electromechanical transducer is preferred. The holding jig 20 shown in FIG. 3 is a first example of such a holding jig.

This holding jig 20 has two measuring terminals (electrical measuring probes) 2 that are in contact with the two electrodes 1 1 a · 1 1 b arranged on the same plane (upper surface) of the electromechanical transducer 10. 1 a · 2 1 b, a support member 2 2 that supports the electromechanical conversion element 10 in contact with the surface (bottom surface) facing the electrode 1 la, 1 lb mounting surface, and the measurement terminal 2 1 a · Mechanically connecting measurement terminal holding part 2 3 holding 2 1 b, support member holding part 2 4 holding support member 2 2, measurement terminal holding part 2 3 and support member holding part 2 4 The connecting part 2 5 a · 2 5 b is provided. The holding jig 20 uses these materials to hold the electromechanical transducer 10 and from the electrodes 1 1 a and 1 1 b via the measurement terminals 2 1 a and 2 1 b. It is configured to take out two electrical wires. That is, an electrical wiring connected to an electrical measuring instrument to be described later is connected to the end of the measuring terminals 2 l a · 2 l b on the side not contacting the element 10.

The holding jig 20 ′ shown in FIG. 4 is a second example of a jig that can hold the element 10 so as to reduce the influence of the element 10 on the vibration state. The holding jig 20 ′ includes a support member 2 2 of the holding jig 20 and a pedestal 2 6 in place of the support member holding portion 2 4. The holding jig 20 ′ is configured to support the entire surface (lower surface) facing the arrangement surface (upper surface) of the electrode 1 la · 1 lb of the element 10 by the pedestal 26. This is different from the holding jig 20 only in the point.

FIG. 5 shows the flow of the steps (steps) of the “electromechanical characteristics inspection method for electromechanical transducers” according to the embodiment of the present invention. In this electromechanical characteristic inspection method, first, in step 1, the electromechanical conversion element 10 is held by a holding jig, and in step 2, the electrode of the electromechanical conversion element 10 is connected to the AC admittance. Electrically connected to the meter The AC admittance frequency characteristic data is obtained by measuring the AC admittance frequency characteristics of the electromechanical transducer 10, and in step 3, the characteristic peak value (characteristic Maximum value) A max and resonance sharpness Q are calculated, and the value k (= A max / Q) obtained by dividing the characteristic peak value A max by the resonance sharpness Q in step 4 is used as the evaluation index value. Determining whether element 10 is good (determining whether electromechanical characteristics of element 10 are good).

The holding method of the electromechanical conversion element 10 in step 1 is not particularly limited, and a holding method according to the prior art can be applied. However, in order not to greatly affect the vibration state of the electromechanical transducer 10, a holding jig with little contact with the element 10, such as the holding jig 20 and 2 0 ′ described above, may be used. It is preferable to use and hold element 10.

The method for measuring the frequency characteristics of the AC admittance of the electromechanical transducer 10 in step 2 above is not particularly limited. For example, a frequency characteristic measuring instrument such as a network analyzer or impedance analyzer is used. Any conventional method may be used.

The measurement results of the frequency characteristics of the AC admittance of one electromechanical transducer element 10 (referred to as “first element” for convenience) are shown in FIG. 6 and FIG. Figures 8 and 9 show the measurement results of the frequency characteristics of the AC admittance. As can be seen from Figs. 6 and 7, the first element has one resonance peak within the measurement frequency range. As can be seen from FIGS. 8 and 9, the second element has two resonance peaks within the measurement frequency range.

As is well known, AC admittance characteristics (frequency characteristics of AC admittance) are expressed by a set of data composed of the amplitude and phase of the admittance. It can also be expressed by a set of data consisting of conductance, which is the cosine component of admittance, and susceptance, which is the sine component. Both of these data can be converted to each other. Fig. 7 is a graph plotting the result of converting the data of the amplitude and phase of the admittance shown in Fig. 6 into the data of conductance and susceptance. Fig. 9 is a graph plotting the data shown in Fig. 8 in the same way. As is well known, the AC admittance characteristics near the resonance frequency of the electromechanical transducer can be expressed by an electrical equivalent circuit. Examples of circuit diagrams of such an equivalent circuit are shown in Figs. 10 and 11. FIG. 10 is an equivalent circuit diagram of the first element having only one resonance peak, and FIG. 11 is an equivalent circuit diagram of the second element having two resonance peaks.

In step 3 above, the method for calculating “characteristic peak value A max and resonance sharpness Q” from the measurement data of the frequency characteristics of the AC admittance is not particularly limited. Any technique may be used. As the characteristic peak value A ma, the peak value of the AC admittance, the peak value of the AC conductance, the peak value of the AC impedance phase, and the like can be suitably used. In particular, it is preferable to use the peak value of the AC conductance as the characteristic peak value A max. This is because the correspondence between the value obtained by dividing the peak value of the AC conductance by the resonance sharpness and the characteristics of the electromechanical conversion device after the electromechanical conversion element is assembled is particularly good. It is.

When the peak value G max of the AC conductance G is used as the characteristic peak value A max, the following values can be used as the calculation method for the peak value G max. .

(A) Peak value (maximum value) of the measured AC conductance G values. (B) The difference between the maximum value B max and the minimum value B min of the measured AC susceptance B (B max – B min).

(C) On the graph with AC conductance G on the X-axis and AC susceptance B on the Y-axis, the data consisting of the `` Measured value of AC conductance G and Measured value of AC susceptance B '' force Diameter of “AC admittance circle” obtained by plotting 1 ZR 1.

In this case, if the AC admittance circle diameter 1 Z R 1 is used as the peak value G max of the AC conductance G, repeated measurement reproducibility is further improved. The diameter 1 Z R 1 of the AC admittance circle can be calculated (obtained) by a known calculation method such as “Fitting a circle to the circle plot data” or the least square method.

When calculating the resonance sharpness Q from the measurement data on the frequency characteristics of AC admittance (AC admittance frequency characteristics data), the resonance frequency f 0 is set to the peak half-value width of the AC conductance G (AC The inductance G is divided by the difference between two frequencies f 1 and f 2 (f 2-f 1, f 2> f 1)) at which the peak value G max is half (0.5 G max). The method can be used. Further, the frequency characteristic measurement data is usually discrete data for each predetermined frequency step. Therefore, interpolation calculation (frequency data capture) is performed on the values between the wave number steps, and the resonance frequency f 0 and peak half-value width (f It is preferable to calculate the Q value using 2-f 1) and to increase the resolution of the Q value.

The value obtained by dividing the characteristic peak value A max by the resonance sharpness Q. Use A max / Q as the evaluation index value to determine the quality of the electromechanical transducer (characteristic quality). This means that pass / fail is judged according to whether A max / Q is within a predetermined range. That is, if the value A max / Q is within the predetermined range, the electromechanical conversion element is determined to be a good element, and if the value A max / Q is not within the predetermined range, the electromechanical conversion element is not good. It is determined that Normally, the larger the value A max / Q, the greater the electromechanical conversion efficiency. Therefore, it can be determined that the element has more favorable characteristics as the value A max / Q increases. Therefore, it is only necessary to set a lower limit value for the value A max / Q, and to determine that the electromechanical transducer having the value A max / Q equal to or higher than the lower limit value has good characteristics.

-On the other hand, depending on the application of the electromechanical transducer, there may be inconvenience if the electromechanical transformation (conversion efficiency) is too large. In such a case, an upper limit value may be further set for the value A max / Q, and the electromechanical transducer having the value A max / Q equal to or lower than the upper limit value may be determined to have good characteristics. . That is, not only the lower limit value but also the upper limit value for the value A max / Q can be added to the pass / fail judgment condition of the electromechanical transducer.

Also, depending on the application of the electromechanical transducer, if the electromechanical transducer is an element having a “parasitic resonance” that is different from the “main resonance” used for the original application, the parasitic resonance may May adversely affect

Ό. Such an electromechanical transducer has an AC admittance characteristic having resonance peak points at two locations as shown in FIGS. 8 and 9, and has a value for each of the main resonance and the parasitic resonance. Calculate A max / Q

It is preferable to set pass / fail judgment conditions for each resonance value A max / Q. As a result, the quality of the electromechanical transducer can be determined more appropriately. In this case, for example, the value of the main resonance A An element in which max / Q is equal to or higher than a predetermined lower limit value and the parasitic resonance value A maxZ Q is equal to or lower than a predetermined upper limit value may be determined as a non-defective product.

In this way, if the value A maxZ Q (or the reciprocal value Q no A max) obtained by dividing the characteristic peak value A max by the resonance sharpness Q is used as the performance index value, The effect of variations in measurement results due to the holding state of the element can be reduced. In addition, even when the electromechanical transducer is actually incorporated into a device, the value A max / Q shows a strong correlation with the performance of the device even if it is held in a state different from that during measurement. From these facts, if the value A max / Q is used as the performance index value, the quality of the single electromechanical element to be incorporated into the electromechanical conversion device can be judged well. This is because the measured value of the characteristic peak value A max and the measured value of the resonance sharpness Q fluctuate depending on the state where the electromechanical transducer is held, whereas the characteristic peak value A max The value A max / Q, which is obtained by dividing the measured value by the measured value of the resonance sharpness Q, is not easily affected by the holding state of the electromechanical conversion, and shows the original electromechanical conversion performance of the electromechanical conversion element. It is believed that there is.

On the other hand, as a method for directly measuring the electromechanical conversion characteristics of the electromechanical conversion element, there is a method for measuring vibration displacement (vibration displacement characteristics, amplitude characteristics). The vibration displacement characteristics can be measured, for example, by using a laser Doppler vibrometer and a frequency characteristic measuring instrument. Fig. 12 shows an example of a block diagram of the vibration displacement measurement system, and Fig. 13 shows an example of the vibration displacement measurement method.

In the example shown in Fig. 12, the frequency sweep signal V out from the frequency characteristic measuring device 3 1 is applied to the electromechanical transducer 10 as the voltage Vin through the power amplifier 3 2 and at the same time Measure the vibration speed of 1 0 with the laser Doppler vibrometer 3 3 (obtain the vibration speed signal S v) and measure the applied voltage V in and the vibration speed signal SV with the frequency characteristic measuring instrument 3 1 By doing so, the vibration displacement characteristics of element 10 are measured by frequency sweep. The broken line LB represents the laser beam.

In the example shown in FIG. 13, when the electromechanical transducer 10 is held by a holding jig similar to the holding jig 20 shown in FIG. 3, the upper electrode of the element 10 ( Electrode terminal) While probing 1 1 a · 1 1 b (ie, while measuring terminal 2 1 a · 2 1 b is in contact with electrode 1 la · 1 lb) Longitudinal direction of element 1 0 (up and down on the page) Direction, L direction) The speed is measured by a laser Doppler vibrometer 3 3. A contact member 4 1 that contacts the rotor of an ultrasonic motor described later is provided on the surface of the element 10 facing the laser Doppler vibrometer 33. A broken line LB represents a laser beam.

Figures 14 and 15 show examples of the measurement results (vibration displacement frequency characteristic data) of the electromechanical transducer measured in this way. Fig. 14 (A) is a graph plotting the vibration displacement (amplitude D) against the frequency f, and Fig. 14 (B) shows the phase 0 _{D of the} vibration displacement against the frequency f. This is a plotted graph. (A) and (B) in Fig. 15 are "cosine component of vibration displacement (amplitude D)" and "vibration displacement" converted based on the data shown in (A) and (B) in Fig. 14 (Amplitude) D plot of “sine component of D” with respect to frequency f. (C) in Fig. 15 plots the above data on a graph with the X axis as the cosine component of the vibration displacement (amplitude) D and the Y axis as the sine component of the vibration displacement (amplitude) D. This is a graph obtained. In the examples shown in Fig. 14 and Fig. 15, only one resonance peak exists in the measurement frequency range.

In the case of determining the pass / fail of the vibration displacement characteristics of the electromechanical transducer measured in this way, the peak value (maximum value) of the amplitude D is the same as when determining the pass / fail of the AC admittance. and this use of Dmax and an evaluation index value the value D max / Q _D divided by resonance sharpness Q _D are preferred. This is because, according to experiments by the inventor, it has been found that the value D max / Q _D is not easily affected by the holding state of the element at the time of measurement. In this case, the resonance sharpness Q _D is the resonance frequency fn of the amplitude D and the peak half-value width of the sine component of the amplitude D (f 2-f 1, f 2> f 1, that is, the sine component of the amplitude D is It can be obtained by dividing by the half value of the peak V ma (the difference between the two frequencies f 1 and f 2, which is 0.5 V max) (see (B) in Fig. 15).

The peak value D max of the amplitude D and the resonance sharpness Q _D are the circle fitting and frequency points by the least square method, as in the case of calculating the characteristic peak value Amax of the AC admittance and the resonance sharpness Q. It is desirable to obtain this value using a method that uses interpolation calculation between the two. As a result, the peak value D max and the resonance sharpness Q _D with higher accuracy and better repeatability can be obtained. Thus, in another embodiment of the present invention, a voltage having a predetermined vibration waveform is applied to the electromechanical conversion device via the electrodes 1 1 a and 1 1 b. An electromechanical characteristic inspection method for an electromechanical transducer 10 that generates mechanical vibrations by

A fifth step of holding the electromechanical transducer 10 by holding jigs 20, 20, etc .;

The electrodes 1 1 a · 1 1 b of the electromechanical transducer 10 are electrically connected to a frequency characteristic measuring device 3 1, and the electrode 1 has a frequency range including the resonance frequency of the electromechanical transducer 10. A sixth step of measuring vibration displacement frequency characteristic data representing vibration displacement characteristics between 1 a and 1 1 b;

A seventh step of obtaining a peak value D max and a resonance sharpness Q _D of the amplitude of the vibration displacement that is maximum at the resonance frequency based on the vibration displacement frequency characteristic data measured in the sixth step;

The electromechanical transducer element 1 using the value D max / Q _D obtained by dividing the peak value D max of the amplitude acquired in the seventh step by the resonance sharpness Q _D acquired in the seventh step. An eighth step of performing an electromechanical property test of 0;

including.

As an example of application of the electromechanical transducer 10 to an electromechanical transducer, an ultrasonic motor 40 as shown in Fig. 16 can be cited. The electromechanical transducer 10 used for the ultrasonic motor 40 has a contact member 4 1 attached to its tip. Then, the ultrasonic motor 40 transmits the contact member 41 fixed to the element 10 to the shaft.

(Rotating shaft) A structure that presses against the rotor 4 3 rotatably supported by the 4 2 is provided. This ultrasonic motor 40 is a so-called “woodpecker type ultrasonic motor”. In the ultrasonic motor 40, a drive signal (that is, a voltage having a predetermined vibration waveform) in the vicinity of the expansion / contraction resonance frequency in the longitudinal direction is applied to the electromechanical conversion element 10, and the element 10 is long. Generate direction stretching vibration. As a result, the contact member 4 1 pushes the rotor 4 3 obliquely, and as a result, the rotor 4 3 rotates.

(Example 1)

The electromechanical transducer 10 as shown in FIGS. 1 and 2 is held by using a holding jig 20 as shown in FIG. 3 and disposed on the surface of the element 10. Connected to the upper electrode 1 1 a 1 1 b to the measuring terminal 2 1 a 2 1 b Measured data showing AC admittance characteristics of element 10

(AC admittance frequency characteristic data) is obtained by frequency sweep measurement using a network analyzer, and the characteristic peak value A max and resonance sharpness Q, etc. are measured from the measured characteristic data. The measurement to determine the value was repeated 10 times for the same element 10. The element 10 used in this measurement is an element in which a PZT piezoelectric body having a thickness of about 60 m is laminated via the electrodes 14 a and 14 b described above, and its length is L is 5 mm, width W is 1.5 mm, and thickness H is 1.5 mm.

Tables 1 and 2 show the 10 measurement results obtained in this way. Table 1 was obtained without using circular fitting and frequency data interpolation from the frequency characteristic measurement data for each AC admittance (i.e., without interpolation calculation). “Resonance sharpness Q (Q 镇)”, “AC admittance peak value Ymax”, “Conductance peak value G maxj and“ susceptance B ” The difference between the maximum value B 2 and the minimum value B 1 (B 2-B 1) ”.

Table 2 shows how to perform circular fitting and frequency data interpolation from “frequency characteristics measurement data for each AC admittance”, which is the same as the data shown in Table 1. 2 is a list of “resonance sharpness Q (Q value)” and “admittance circle diameter 1 / R 1” calculated by the above. Tables 1 and 2 list the average, standard deviation, and variation ratio of the 10 measurements. Here, the fluctuation ratio is a value obtained by dividing the standard deviation by the average value. The fluctuation ratio is a value that indicates the relative degree of repeated measurement variation.

t

Repeated measurement value 2 (Calculation method using data interpolation)

Measurement number fs f1 f2 Q 1 / R1 1 / QR1

[kHz] [kHz] [kHz] [mS] CuS]

1 319.91 319.61 320.21 540 1109 2054

2 319.97 319.49 320.44 339 691 2045

3 320.01 319.71 320.31 534 11 17 2095

4 320.07 319.83 320.31 666 1439 2175

5 319.92 319.68 320.1 6 662 1330 2023

6 319.93 319.51 320.35 379 785 2081

7 319.94 319.70 320.1 8 663 1443 2180

8 320.02 319.64 320.40 417 838 201 2

9 319.91 319.63 320.20 556 1144 2065

10 319.96 319.68 320.24 571 1208 2131

Average m 319.96 319.65 320.28 533 11 10 2086

Standard deviation σ 0.05 0.10 0.1 0 119 265 59

Fluctuation ratio σ / ηπ 0.02% 0.03% 0.03% 22.4% 23.9% 2.8% Table 2

As shown in Tables 1 and 2, AC admittance peak value Y max, conductance peak value G max, maximum susceptance difference (B 2-B 1) and admittance The four measured values of the diameter circle 1 ZR 1 have a variation ratio of about 24%. On the other hand, the fluctuation ratio of the value obtained by dividing each of the four measured values by the Q value is about 3 to 6%, which is relatively small. From this, the value obtained by dividing each of the four measured values by the Q value (Y max / Q, G max / Q, (B 2-B 1) no Q, 1 / (Q · R 1)) is It is understood that the reproducibility of repeated measurement is good. Among these values, the value calculated using “circle fitting and frequency data interpolation” (1 / (Q · R 1)) has a very small fluctuation ratio of about 3%, and is repeatedly measured. Reproducibility is very good Figure 17 is a graph based on the data shown in Tables 1 and 2, and is a correlation plot between the Q value and the peak value Y max of the AC admittance. . Figure 17 shows that the Q value and the peak value Y max of AC admittance are approximately proportional. In particular, the (D) force in Fig. 17 shows the Q value calculated using circular fitting and frequency data interpolation. It is understood that there is a very high correlation (clear proportionality) with the diameter 1 / R l of the admittance circle. These factors indicate that each of the Q value and the admittance peak value Y max changes depending on the holding state of the element, but its proportionality coefficient k = l Z (Q · R 1) Each is unique.

(Example 2)

Prepare 10 electromechanical transducers 10 as shown in Fig. 1 and Fig. 2 and hold each of them using a holding jig 20 as shown in Fig. 3. The measurement terminals 2 1 a and 2 1 b are brought into contact with the upper electrodes 1 1 a and 1 1 b arranged on the surface of each element 10, and the AC admittance characteristics of each element 10 are measured. Data (AC admittance frequency characteristic data) is obtained by frequency sweep measurement using a network analyzer, and the characteristic peak value A of each element 10 is obtained from the measured characteristic data. Values such as max and resonance sharpness Q were obtained. Thereafter, the vibration displacement characteristics (vibration displacement frequency characteristic data) of each of the same 10 elements 10 were also measured by the method shown in FIGS. 12 and 13. Each element 10 is an element in which a PZT piezoelectric body having a thickness of about 60 m is laminated through the above-mentioned electrodes 14 a and 14 b, and its length L is 5 mm, Φ畐 W is 1.5 mm and thickness H is 1.5 mm.

The measured values obtained from the AC admittance frequency characteristic data of 10 elements 10 without using circular fitting and frequency data interpolation (that is, without performing interpolation calculation) The conductance peak value G max and the resonance sharpness Q are obtained, and the diameter of the admittance circle 1 ZR 1 and the resonance sharpness are further obtained by using circular and frequency data capture. Degree Q was calculated. In addition, the diameter D max of the displacement circle and the resonance sharpness Q _D were calculated from the frequency characteristic data of the displacement (vibration displacement frequency characteristic data) using circular fitting and frequency data interpolation. Based on the 10 sets of data obtained in this way, four admittances consisting of G max, G max / Q, 1 / R l and 1 / (Q-R 1) For each characteristic measurement value, a correlation coefficient with the square of the displacement characteristic measurement value D max / Q _D was calculated. The results are shown in Table 3 and Figure 18. Fig. 18 is a plot showing the correlation between the admittance characteristics shown in Table 3 and the displacement characteristics (vibration displacement characteristics). Measurement results of admittance characteristics of a single element Measurement results of displacement characteristics of a single element Measurement value 1 Measurement value ί Measurement value

Sample (value without data pain) (data value) (data value)

Number Q Gmax Gmax / QQ 1 / R1 1 / QR1 Q _D Dmax Dmax / Q _D (Dmax / Q _D ) ²

[mS] CuS] CmS] [uS] [nm / V] [nm / V] [nm / V]

1 533 1032 1935 544 1046 1924 220 139 0.634 0.402

2 356 452 1271 360 452 1257 182 95 0.523 0.274

3 400 667 1669 358 669 1869 193 129 0.668 0.447

4 640 1012 1581 597 1018 1704 195 121 0.619 0.384

5 400 484 121 1 419 485 1156 218 106 0.486 0.236

6 457 758 1658 460 759 1650 213 133 0.626 0.392

7 640 813 1270 544 838 1541 197 1 1 1 0.562 0.316

8 320 471 1473 310 471 1521 208 24 0.596 0.355

9 400 557 1392 377 558 1478 196 1 10 0.560 0.314

10 640 1 176 1837 630 1177 1867 210 136 0.648 0.420

(Dmax / Q _D ) ²

Against 41.6% 77.3% 40.6¾ 91.3%

Correlation coefficient

Table 3

As shown in Table 3, the conductance peak value G max and the admittance circle diameter 1 ZR 1 have a correlation coefficient of about 40% with the square of the measured displacement characteristics D max / Q _D Low, displacement characteristics measured value D max / Q _D is not good correlation with the square of _D. In contrast, the conductance peak value G max and the admittance circle diameter 1 ZR 1 are each divided by the resonance sharpness Q (G max / Q, 1 / (Q · R 1)) Has a correlation coefficient with the square of the displacement characteristic measured value D max / Q _D of about 75 to 90%, and the correlation with the square of the displacement characteristic measured value D maxZ Q _D is good. In particular, the value (1 / (Q-R 1)) has a correlation coefficient of 90% or more, and the correlation with the displacement characteristics is very high, as can be seen from (D) in Fig. 18. It turns out to be good.

(Example 3)

Ten electromechanical transducers 10 whose AC admittance characteristics and vibration displacement characteristics were measured in Example 2 were incorporated into an ultrasonic motor 40 as shown in Fig. 16, and each ultrasonic wave was measured. The characteristics of the motor 40 were measured. Four admittance characteristics consisting of G m ax, G max / Q, 1 / R 1, 1 / (Q · R 1) force from 10 sets of data obtained in this way For each measured value, the corresponding ultrasonic motor 4 The correlation coefficient with the square of the rotational speed of 0 was calculated. The results are shown in Table 4 and FIG. Fig. 19 is a plot showing the correlation between the admittance characteristics shown in Table 4 and the ultrasonic motor characteristics.

Table 4

As shown in Table 4, the conductance peak value G max and the admittance circle diameter 1 ZR 1 are as low as about 56% of the correlation with the square of the rotational speed of the ultrasonic motor. The correlation with the square of the rotation speed of the ultrasonic motor is not good. On the other hand, the conductance peak value G max and the diameter 1 ZR 1 of the admittance circle are divided by the resonance degree Q (G max / Q, 1 / (Q-R 1 )) Has a correlation coefficient with the square of the rotational speed of the ultrasonic motor, which is about 80 to 95%, and has a good correlation with the square of the rotational speed of the ultrasonic motor. In particular, the value (1 / (Q · R 1)) has a correlation coefficient of 95% or more, and as can be seen from (D) in Fig. 19, the correlation with the ultrasonic motor characteristics is high. It turns out to be very good.

(Another embodiment)

The electromechanical characteristic inspection method according to the present invention can also be applied to the evaluation of the displacement characteristics of a quasi-statically driven electromechanical transducer. Quasi-statically driven An electromechanical transducer that can be used is a voltage waveform that alternates at a very low frequency compared to the lowest resonance frequency of the device, or a very long time compared to the lowest resonance frequency of the device. An element that is displaced when a voltage waveform is applied and when the voltage is applied.

The electromechanical transducer element 100 shown in FIGS. 20 and 21 is an example of such an “electromechanical transducer element driven quasi-statically”. FIG. 20 is a trihedral view showing the external appearance of the electromechanical transducer element 100, and FIG. 21 is an exploded perspective view showing the laminated structure of the electromechanical transducer element 100.

The electromechanical transducer 100 is formed by stacking a plurality of layered PZT piezoelectric bodies 100 a sandwiched between two kinds of film-like internal electrodes 10 4 a and 10 4 b. It is a laminated piezoelectric element. Side electrodes 1 0 2 a and 1 0 2 b are formed on the side surfaces of the element 1 0 0. The plurality of internal electrodes 10 04a are electrically connected to each other by side electrodes 10202a. The plurality of internal electrodes 10 4 b are electrically connected to each other by side electrodes 10 0 2 b.

When a voltage is applied between the side electrode 1 0 2 a and the side electrode 1 0 2 b, the element 1 0 0 extends in the thickness direction (height H direction) due to the inverse piezoelectric effect, and the length direction It deforms so that it shrinks in the L direction and the W direction (that is, it generates mechanical displacement). Therefore, by measuring the “frequency characteristics of AC admittance” between the side electrode 10 2 a and the side electrode 10 2 b with a network analyzer, the length direction and thickness Electromechanical characteristic values such as longitudinal resonance frequency, resonance sharpness (Q value), AC conductance G and AC susceptance B can be measured.

The holding jig 20 0 shown in FIG. 22 is an example of a holding jig that holds the element 10 0 0 when the electromechanical characteristic value of the element 1 0 0 is measured. The holding jig 20 0 is composed of a measurement terminal (electric measurement probe) 2 0 la that contacts the side electrode 1 0 2 a of the electromechanical transducer 1 100 and the side electrode 1 0 of the electromechanical transducer 1 0 0. 2 b Measuring terminal (electrical measuring probe) that contacts b 2 0 1 b and. Furthermore, the holding jig 20 0 includes a measuring terminal holding unit 20 3 for holding the measuring terminal 2 0 1 a, a measuring terminal holding unit 2 0 4 for holding the measuring terminal 2 0 1 b, and a measuring terminal holding unit. 2 0 5 a and 2 0 5 b are provided for mechanically connecting 2 0 3 and the measurement terminal holding portion 2 0 4.

The holding jig 2 0 0 uses these members to make an electromechanical conversion element 1 Hold 0 0 as shown in Fig. 2 2 and measure terminal 2 O la

• It is configured to take out two 5 ^ Sd wires from side electrode 1 0 2 a • 1 0 2 b via 2 0 1 b. That is, the measurement terminal 2 0 1 a 2

An electrical wiring extending to the electrical measuring instrument is connected to the end of the 0 1 b that does not contact the element 1 0 0.

As shown in Fig. 2 (B), the holding jig 20 0 is connected to the electromechanical transducer 10 0 between the measurement terminals 2 0 1 a and 2 0 1 b.

”. At this time, the measuring terminal 2 0 1 a and the measuring terminal 2 0 1 b are bent (bent) in opposite directions to each other (that is, the side electrodes 1 0 2 a · 1). 0 2 b) and contact at an acute angle.

According to this embodiment, “electromechanical property inspection method for electromechanical transducer”

The process flow (step) is the same as that of the above-described embodiment, and follows the flow shown in FIG. However, since the turtle ¼ mechanical conversion element 100 0 is an element that is quasi-statically driven after being incorporated in the electromechanical conversion device, the electromechanical conversion element 10 0 Vibration transducer when incorporated into a mechanical conversion device and actually driven Vibration measurement similar to J is obtained. In the case of o, the resonance form at the lowest resonance frequency of the electromechanical transducer element 100 is most similar to the vibration form at the time of actual driving of the electromechanical transducer element 100 Therefore, the characteristic peak value (maximum characteristic value) A max and resonance sharpness Q in Step 3 and Step 4 are the characteristic peak value and resonance at the lowest resonance frequency of the electromechanical transducer 100. Sharpness.

(Example 4)

In Example 4, the following measurement was performed.

1) Ten electromechanical transducer elements 100 as shown in Fig. 20 and Fig. 21 were prepared. Each of the electromechanical transducer elements 100 has a thickness of about 2 0 111? This is an element in which two piezoelectric elements are stacked via electrodes 104 and 10 4 b.The length L is 1.2 mm, the width W is 1.2 mm, and the thickness H is 1. O mm.

2) Each of the 10 electromechanical transducer elements 100 was held in turn using a holding jig 2 00 shown in FIG. At this time, as shown in FIG. 22, the side electrode disposed on the side surface of the electromechanical transducer 100. Measurement terminals 2 0 1 a · 2 0 1 b were brought into contact with 1 0 2 a · 1 0 2 b, respectively.

3) Connect measurement terminal 2 0 la · 2 0 lb to the network analyzer, and measure data indicating the AC admittance characteristics of the element 1 0 0 held by the holding jig 2 0 0 (AC Dotance frequency characteristic data) ”was obtained by frequency sweep measurement using the network analyzer.

4) From the measured (acquired) AC admittance frequency characteristic data, the values of the characteristic peak value A max and resonance sharpness Q of each of the 10 elements 100 were obtained. In this case, the characteristic peak value Amax, the resonance sharpness Q, etc. are the values at about 1 MHz for the “lowest resonance frequency” of the electromechanical transducer 100.

5) By using circular fitting and frequency data interpolation from the AC admittance frequency characteristic data of 10 electromechanical transducer elements 100 obtained in this way, The “admittance circle diameter 1 / R l” and “resonance sharpness Q” were calculated.

Thereafter, measurements as described below were performed, and quasi-static displacement characteristic data was obtained for each of the 10 electromechanical transducer elements 100.

6) As shown in Fig. 23, each of the 10 electromechanical transducers 100 was held in order. That is, the electromechanical conversion element 1 0 0 is arranged on the top of the base 2 0 8, and the voltage application terminals 2 0 9 a 2 0 9 b are brought into contact with the side electrodes 1 0 2 a 1 0 2 b, respectively. .

7) Using the measurement system shown in Fig. 24, we measured the quasi-static displacement characteristics (quasi-static displacement characteristics data) of the element 100 located above the pedestal 20 8. More specifically, in the measurement system shown in FIG. 24, the output V out of the signal generator 2 1 0 is connected to the “drive voltage via the power amplifier 2 1 2 and voltage application terminal 2 0 9 a”. V in 1 ”is marked on the side electrode 10 2 a. Voltage application terminal 2 0 9 b is grounded. The drive voltage Vin l is input to the oscilloscope 2 1 4. The laser Doppler displacement meter 2 1 6 measures the displacement of the electromechanical transducer 10 0 using the laser beam L B (converts it into an electrical signal V in 2). The measured displacement (electrical signal Vin2) is input to the oscilloscope.

The drive voltage V in 1 has a frequency of 2 kHz and amplitude (maximum voltage and minimum voltage). Is the sine wave voltage of 6 V. The quasi-static displacement characteristics data of the electromechanical transducer 100 were obtained by observing the electrical signal (output voltage) V in 2 from the Doppler displacement meter with an oscilloscope 2 14. That is, the amplitude of the waveform of the output voltage V in 2 was measured, and the measured amplitude was obtained as quasi-static displacement characteristic data (displacement amount D).

Here, the “resonance frequency with the lowest frequency” of the electromechanical transducer 100 is about 1 MHz. Therefore, when the electromechanical transducer 10 0 is driven by a sinusoidal drive voltage Vin l with a frequency of 2 kHz, the electromechanical transducer 1 0 0 is “sufficiently compared to the lowest resonance frequency”. Driven at “low frequency”. As a result, the amount of displacement D when the electromechanical transducer 100 is driven by the drive voltage Vin l is the same as a static voltage (for example, a voltage that is generated only once and has elapsed over time). The voltage changes to a trapezoidal shape, and the difference between the maximum voltage value and the minimum voltage value is 6 V) is approximately equal to the displacement amount when applied to the electromechanical transducer 100.

By the above method, the admittance circle diameter 1 ZR 1, resonance sharpness Q and displacement D were obtained for each of the 10 electromechanical transducers 100. Then, for each of the 10 electromechanical transducers 100, the correlation coefficient between the diameter 1 / R 1 of the dominance circle and the square of the displacement D, value Γ 1 / ( The correlation coefficient between Q * R 1) ”and the square of the displacement D was calculated. The results are shown in Table 5 and Fig. 25. Figure 25 is a plot showing the correlation between the admittance characteristics shown in Table 5 and the quasi-static displacement characteristics (quasi-static displacement characteristics data).

Table 5

As shown in Table 5, the diameter 1 / R 1 of the admittance circle has a low correlation coefficient of about 60% with the square of the displacement D, and the correlation with the square of the displacement D Is not good. In contrast, the diameter of the admittance circle is 1

The value 1 Z (Q · R 1) obtained by dividing R 1 by the resonance sharpness Q has a correlation coefficient of 90% or more with the square of the displacement D and the square of the displacement D It can be seen that the correlation is very good. This can be understood from the comparison between (A) and (B) in Fig. 25. That is, the square of the displacement D and the value 1 / (Q

• It is understood that R 1) and are approximately proportional.

(Still another embodiment)

FIGS. 26 to 28 show other electromechanical transducers 30 0 that are driven quasi-statically. The electromechanical characteristic inspection method according to the present invention can also be applied to this electromechanical transducer element 300. The electromechanical conversion element 300 is an example of an electromechanical conversion element that functions as an actuator having a diaphragm structure (Shodeno Electrostriction Actuator).

The electromechanical transducer 3 0 0 includes a support part 3 1 0 and a vibration part 3 2 0. The support part 3 10 has a window part 3 1 2 for forming a cavity at the center part.

The vibration part 3 20 includes a vibration plate 3 2 2, a lower electrode 3 2 4, a piezoelectric film (P z τ piezoelectric layer) 3 2 6 and an upper electrode 3 2 8. The diaphragm 3 2 2 is a plate that is thinner than the support 3 1 0. Lower electrode 3 2 4 is diaphragm 3 2

2 is formed on the top surface. The piezoelectric film 3 2 6 is formed on the upper surface of the lower electrode 3 2 4. The upper electrode 3 2 8 is formed on the upper surface of the piezoelectric film 3 2 6. That is, the piezoelectric film 3 2 6 is sandwiched between the lower electrode 3 2 4 and the upper electrode 3 2 8. The vibration part 3 20 is integrally fixed to the support part 3 10 so as to cover the window part 3 1 2 of the support part 3 10. When a voltage is applied between the upper electrode 3 2 8 and the lower electrode 3 2 4, the piezoelectric film 3 2 6 is deformed. The electromechanical transducer 3 0 0 causes displacement in ik Λ fe. 3 2 2 due to the deformation of the piezoelectric film 3 2 6.

The flow of “steps” is also the same as the embodiment described above and | RJ, and follows the flow shown in FIG. However, since the electromechanical conversion element 3 0 0 is an element that is quasi-statically driven after being incorporated into the ¾-air mechanical conversion device, the “electromechanical conversion element 3 0 0 is It is preferable to measure the AC admittance characteristics in the frequency region including the resonance frequency that can provide a vibration form similar to that of a vibration form when it is incorporated into a converter and actually driven. In this case, the resonance form of the electromechanical conversion element 3 0 0 at the lowest resonance frequency is most similar to the vibration form during actual driving of the electromechanical conversion element 3 0 0. Therefore, in step 3 and step 4, the characteristic peak value (characteristic maximum value) A max and the resonance sharpness Q are the characteristic peak value and resonance sharpness at the lowest resonance frequency of the electromechanical transducer 100. is there.

(Example 5)

In Example 5, the following measurement was performed.

1) Ten electromechanical transducers 30 0 as shown in FIGS. 26 to 28 were prepared.

2) As shown in FIG. 29, each of the 10 electromechanical transducer elements 30 0 was held in order using a holding jig 4 0 0. At this time, the measurement terminal 4 1 0 a and the measurement terminal are connected to the “upper electrode 3 2 8 and lower electrode 3 2 4” extended on the upper surface of the diaphragm 3 2 2 of the electromechanical transducer 3 300. Four 1 0 b was brought into contact.

3) Connect measurement terminal 4 1 0 a and measurement terminal 4 1 0 b to the network analyzer, and show the `` AC admittance characteristics of element 3 0 0 held by holding jig 4 0 0 “Measurement data (AC admittance frequency characteristic data)” was obtained by frequency sweep measurement using the network analyzer.

4) From the measured (acquired) AC admittance frequency characteristic data, the values of the characteristic peak value A max and resonance sharpness Q of each of the 10 elements 30 were determined.

5) By using circular fitting and frequency data interpolation from the AC admittance frequency characteristic data of 10 electromechanical transducers 30 obtained in this way, “Admittance circle diameter 1 cm R l” and “Resonance sharpness Q” were calculated.

After that, the measurement as described below was performed, and the quasi-static displacement characteristic data was obtained for each of the 10 electromechanical transducer elements 30 0 from which the AC admittance frequency characteristic data was obtained. .

6) Although not shown in Fig. 30, _b HLI 10 Each of the electric machine conversion elements 30 0 was held in turn using the holding jig 50 0.

0 includes a vacuum suction disk 50 2 and an “ultraviolet (UV) peelable adhesive film 50 4 J disposed on the upper surface of the vacuum suction disk 50 2. Electromechanical conversion element 30 0 was adhered and fixed to the top of the adhesive sheet b 50 4 4. The adhesive sheet 50 4 was vacuum-adsorbed to the vacuum suction disk 50 2, at this time as shown in FIG. As shown in the figure, the upper electrode 3 2 8 and the lower electrode 3 BX extended on the upper surface of the diaphragm 3 2 2 of the electromechanical transducer 3 0 0

Measurement terminal 5 1 0 a and measurement terminal 5 1 0 b were brought into contact with 2 4 ”, respectively.

7) Using a measurement system similar to the measurement system shown in Fig. 24, the quasi-static displacement characteristics (quasi-static displacement characteristics data) of the electromechanical transducer 30 0 fixed to the adhesive sheet 50 4 Was measured. In this case, the “drive voltage V in l” shown in FIG. 24 is connected between “upper electrode 3 2 8 and lower electrode 3 2 4 via“ measurement terminal 5 1 0 a and measurement terminal 5 1 0 b ”. ”Is applied. The drive voltage V in l is a voltage having the trapezoidal waveform shown in Fig. 31. The quasi-static displacement characteristics (quasi-static displacement characteristics data) of the electromechanical transducer 1 0 0 are the output voltage V in 2 of the Doppler displacement meter at the oscilloscope 2 1 4 Obtained by observation. At this time, “displacement amount D as quasi-static displacement characteristics data” was obtained based on the amplitude D 1 of the output voltage V in 2 during the period excluding the ring part RIN shown in Fig. 31. .

Meanwhile, the “resonance frequency with the lowest frequency” of the electromechanical transducer 300 is about 1 MHz. Therefore, when the electromechanical transducer 3 0 0 is driven with the “1 ms trapezoidal driving voltage V in 1” shown in FIG. It is driven at a “sufficiently low frequency” compared to a “resonant frequency of low frequency”. As a result, the displacement amount when the electromechanical transducer 300 is driven by the drive voltage V in 1 shown in FIG. 3 1 is a statically similar voltage (for example, a voltage generated only once). The voltage changes to a trapezoidal shape over time, and the difference between the maximum voltage value and the minimum voltage value is 20 V). Will be equal.

Based on the above measurement results, the correlation coefficient between the diameter 1 / R 1 of the admittance circle and the square of the displacement D for each of the 10 electromechanical transducers 300 The correlation coefficient between the value “1 Z (Q * R 1)” and the square of the displacement D was calculated. The results are shown in Table 6 and Fig. 31. Figure 31 is a plot showing the correlation between the admittance characteristics shown in Table 6 and the quasi-static displacement characteristics (quasi-static displacement characteristics data).

Table 6

As shown in Table 6, the diameter 1 ZR 1 of the admittance circle has a low correlation coefficient of about 70% with the square of the displacement D, and the correlation with the square of the displacement D is low. Not good. On the other hand, the value 1 Z (Q · R 1) obtained by dividing the diameter 1 of the admittance circle R 1 by the resonance sharpness Q has a correlation coefficient with the square of the displacement D 9 0 It can be seen that the correlation with the square of the displacement D is very good. This can also be understood from the comparison between (A) and (B) in Fig. 31. That is, it is understood that the square of the displacement amount D and the value 1 / (Q-R 1) are approximately proportional.

In Examples 4 and 5 described above, it was confirmed that a very good correlation between the value 1 / (Q · R 1) and the displacement D was established without depending on measurement variations. It was. Not only the values I and (QR1), but also the peak values of the AC conductance and the peak value of the phase of the AC impedance, etc., and the frequency characteristics of the AC admittance. The value obtained by dividing the “maximum electrical characteristic value A max (characteristic maximum value Amax, characteristic peak value) at the resonance frequency” divided by the resonance sharpness Q (k = Ama _{X /} / Q) There is also a very good correlation between the displacement D and. Therefore, including the value 1 Z (QR1) The value obtained by dividing the peak value A max of the musmitance characteristic by the resonance sharpness Q (proportional coefficient k = A max no Q) is used to evaluate the displacement characteristics of a quasi-statically driven electromechanical transducer. If so, the quality of the electromechanical transducer can be determined with high accuracy.

As described above, in the embodiments and examples according to the present invention, the value obtained by dividing the peak value A ma of the admittance characteristic by the resonance sharpness Q (proportional coefficient k = A max ZQ) is obtained. “It is used as an index value for the electromechanical characteristic inspection J. This gives the peak value of the admittance characteristic.

A max Index value (k is high in repeatability and high correlation with displacement and ultrasonic motor characteristics compared to the comparative example with the index value as the index value.

= A max / Q) can be used for pass / fail judgment of electromechanical transducers. As a result, the quality of the electromechanical transducer can be judged very well.

Claims

1. An electromechanical characteristic detection method for an electromechanical conversion element, which is applied to an electromechanical conversion device and generates a mechanical displacement when a voltage having a predetermined waveform is applied via an electrode. There,

A first step of holding the electromechanical transducer by a holding jig;

The electrode of the electromechanical transducer is electrically connected to an AC admittance measuring device, and the AC admittance between the electrodes is within a frequency range including the resonance frequency of the electromechanical transducer. A second step of measuring AC admittance frequency characteristic data representing frequency characteristics;

Based on the AC admittance frequency characteristic data measured in the second step, the peak value A max and the resonance sharpness Q that are the maximum electrical characteristic values at the resonance frequency are obtained. Step and

Using the value A max / Q obtained by dividing the peak value A max of the electrical characteristic value acquired in the third step by the resonance sharpness Q acquired in the third step. A fourth step of conducting an electromechanical property inspection of the mechanical transducer,

An electromechanical property inspection method including:

2. In the method for detecting the electromechanical characteristics of the electromechanical transducer according to claim 1,

The electrode is disposed on the electromechanical transducer, and in the second step, the electrode is electrically connected to the AC key K-, V-balance measuring device by an electric measurement probe. Electromechanical property inspection method.

3. In the method for inspecting electromechanical characteristics of an electromechanical transducer according to claim 1 or claim 2,

The third step is an electromechanical characteristic inspection method which is a step in which an AC conductance peak value G ma is used as the peak value A max of the electrical characteristic value.

4. Electromechanical characteristics inspection method for electromechanical transducer according to claim 3 In law

The third step is an electromechanical characteristic that is a step of obtaining the peak value G max of the AC conductance by calculating the diameter 1 ZR 1 of the AC admittance circle. Inspection method.

5. It is an electromechanical characteristic inspection method for an electromechanical transducer that is applied to an electromechanical transducer and generates a mechanical displacement when a voltage having a predetermined waveform is applied through an electrode. And

刖記β Sutekupu ^fifth to'll go-between holding a-mechanical換素Ko to hold non- member

When ,

The electrode of the gas-mechanical transducer is electrically measured in frequency characteristics measurement ¾ ^

,

The sixth step of measuring vibration displacement frequency characteristic data representing the vibration displacement characteristics between the recording electrodes in the frequency range including the vibration IdEl wave number of the electromechanical transducer element

A seventh step of obtaining the peak value D max of the amplitude of the vibration displacement and the resonance sharpness Q _D which are the maximum at the resonance frequency based on the vibration displacement frequency characteristic data measured by the above 6 stenno;

The value D max / Q _D of the amplitude peak value D max obtained in the seventh step divided by the resonance sharpness Q _D obtained in the seventh step is used for the electromechanical transducer. An eighth step of conducting an electromechanical property test;

An electromechanical property inspection method including:

6. In the electromechanical transducer testing method according to any one of claims 1 to 5, the main constituent material of the electromechanical transducer is a piezoelectric material or an electrostrictive material. An electromechanical property inspection method characterized by this.