JPH0421370A - Ultrasonic motor - Google Patents

Abstract

PURPOSE:To obviate the necessity of an additional oscillating state detecting means by employing one of a pair of electrostriction elements secured to a resilient oscillator, which is not fed with power, as a detecting means. CONSTITUTION:Electrostriction elements 12a, 12b are secured to the opposite faces of a planer resilient oscillator 10. The electrostriction elements 12a, 12b are connected, respectively, with one ends of lines 13a, 13b having the other ends forked in the way and connected, respectively, with the terminals 14a, 14b of a switching mechanism 14 and the terminals 15a, 15b of a switching mechanism 15. A driving means 50 applies an AC voltage having a specific frequency on any one of the electrostriction elements 12a, 12b through switching of the switch 14. A detecting means 60 periodically detects an AC voltage induced in any one of the electrostriction elements 12a, 12b through switching of the switch 15C. In other words, excitation and detection are carried out through switching of the switches 14C, 15C.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ultrasonic motor device, particularly an ultrasonic motor device driven by a single-phase tV! The present invention relates to an ultrasonic motor device capable of detecting the resonance state of a controlled elastic vibrating body and driving and controlling the elastic vibrating body at an optimal resonance frequency.

[Conventional technology]

Conventionally, ultrasonic motor devices that utilize ultrasonic vibrations are classified based on the type of vibration generated in an elastic vibrating body: standing wave type ultrasonic motor devices that use standing waves and traveling wave type that use traveling waves. There are two types of ultrasonic motor devices.

Among the above, standing wave type ultrasonic motor devices include:
A single bending vibration is excited in the elastic vibrator by a single-phase power supply,
A flat plate-shaped ultrasonic motor device is known that utilizes the driving force directed toward the nodes of this bending vibration via a motion extractor (
For example, a patent application filed in 1983 filed by the same applicant as the present application.
137395).

In addition, the elastic vibrating body has two independent vibration modes: longitudinal vibration (vibration spreading in the length direction of the elastic vibrating body) and bending vibration having a vibration component approximately perpendicular to one surface of the elastic vibrating body. of,
A flat ultrasonic motor that generates elliptical motion on the surface of an elastic vibrating body by exciting it with power supplies (two-phase power supplies) on each side, and transmits this elliptical motion to a motion extraction body and uses it as driving force. The device is known. This type of flat ultrasonic motor device driven by a two-phase power source generates elliptical motion on the surface of an elastic vibrating body by exciting two vibration modes with a temporal phase difference. By switching the rotation direction, the motion direction of the motion extracting body can be switched between forward and reverse directions.

Furthermore, an improved type of device that uses a single-phase power source has been proposed as an improved type of device that makes it possible to forward and reverse the motion extractor using two independent vibration modes excited by the two-phase power source (for example, (See Japanese Patent Application No. 1-137983, Japanese Patent Application No. 1137985, and Japanese Patent Application No. 1-138698 filed by the same applicant as the present application).

[Problem to be solved by the invention]

In the traveling wave type ultrasonic motor device or the standing wave type ultrasonic motor device described in the conventional technology, in order to stably drive the device, when applying an alternating current to an electrostrictive element such as a ceramic, In addition to the driving electrostrictive element that excites the elastic vibrating body, which requires changing and maintaining the frequency in an optimal state, there is also a detection electrostrictive element that picks up the excitation state of the elastic vibrating body. was installed separately on the elastic vibrator.

This uses a voltage generated in accordance with the distortion of the detection electrostrictive element to optimally control the frequency of the alternating current applied to the driving electrostrictive element.

Therefore, a detection electrostrictive element and its detection circuit are separately added to the conventional device, which increases the cost of the device and
This results in disadvantages such as complication of the device.

Furthermore, among the conventional techniques, an ultrasonic motor device of the type that uses a rectangular power source to enable forward and reverse rotation of a motion extracting body is one that uses either one of a pair of electrostrictive elements provided on an elastic vibrating body. Forward or reverse is selected depending on whether an alternating current is applied to the electrostrictive element, but since alternating current of the same frequency is applied to different electrostrictive elements, variations in manufacturing the device, such as the difference in the electrostrictive element itself, may occur. Due to variations in characteristics and size, variations in the adhesive position of the electrostrictive element to the elastic vibrating body, or variations in the thickness of the adhesive layer, electrostrictive elements for forward rotation and reverse rotation cause resonance in the elastic vibrating body. This has the problem that a slight deviation occurs in the frequency of the signal.

The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to provide a method for resonating one of a pair of vibrators without using an additional structure as in the prior art. It is an object of the present invention to provide an ultrasonic motor device that is capable of detecting the vibration state of an elastic vibrating body by using one of the two, and is also capable of exciting the elastic vibrating body in a stable state at all times.

Furthermore, it is an object of the present invention to provide an ultrasonic motor device that can drive and control the forward and reverse rotation of a motion extractor in a stable and well-balanced manner at all times.

[Means for solving problems]

In order to achieve the above object, an ultrasonic motor device according to the invention as set forth in claim 1 includes: At least a pair of electrostrictive elements are fixed to one surface or opposing surfaces of the vibrating body, and an alternating voltage of a specific frequency is applied to each of the electrostrictive element pairs to generate the longitudinal vibration and the bending vibration in the elastic vibrating body. a driving means for generating both vibrations, a first switching means for switching and applying an alternating voltage of the frequency to one of the pair of electrostrictive elements, and detecting a voltage generated in the pair of electrostrictive elements. a second switching means for switching and connecting the detecting means to one of the electrostrictive elements; and a second switching means for switching and connecting the detecting means to one of the electrostrictive elements; at least one motion extracting body that contacts the elastic vibrating body at a position other than the elastic vibrating body.

In a device having such a configuration, the vibration state of the elastic vibrating body can be detected by one electrostrictive element to which an alternating voltage of a specific frequency is not applied.

Further, the ultrasonic motor device according to the invention described in claim 2 includes a plate-shaped elastic vibrating body that is excited with longitudinal vibration in a predetermined mode and bending vibration in a predetermined mode; at least a pair of electrostrictive elements fixed to a surface of the elastic vibrator, and an alternating voltage of a specific frequency is applied to one of the electrostrictive element pairs to generate both the longitudinal vibration and the bending vibration in the elastic vibrating body. at least one motion extractor that contacts the elastic vibrating body at a position that substantially eliminates nodes of the longitudinal vibration and the bending vibration generated in the elastic vibrating body; and the driving means. a frequency varying means connected to the electrostrictive element for varying the frequency applied to the electrostrictive element in an upward or downward direction; a detecting means for detecting a voltage generated in the other of the electrostrictive element pair; A peak hold means for holding a peak value of the detection voltage to be detected compares the detection voltage with a reference voltage generated by dividing the peak value, and determines that the detection voltage has become equal to or lower than the reference voltage. In this case, the apparatus comprises a religious means for generating a predetermined signal, and a means for inverting and controlling the direction of frequency variation by the varying means based on the signal.

In a device having such a configuration, among the electrostrictive element pair,
No matter which one is selected to vibrate the elastic vibrator, the vibration state can be controlled in a well-balanced manner.

[Effect]

That is, the ultrasonic motor device according to the present invention has the above-described configuration, so that one of the at least one pair of electrostrictive elements fixed to the elastic vibrating body does not excite the elastic vibrating body. The vibration state of is detected as a voltage value, and based on the reference voltage generated based on this detected voltage,
Since the side wave number of the alternating voltage applied to the other electrostrictive element that vibrates the elastic vibrator is controlled within a certain range, it is possible to use an ultrasonic motor! There is no need to provide a separate means for detecting the vibration state of the elastic vibrating body, and even if any of the electrostrictive elements of the pair is selected to excite the elastic vibrating body, the vibration state of the elastic vibrating body can be detected. This makes it possible to control in a well-balanced manner.

[Driving principle of the ultrasonic motor device according to the present invention] The resonant frequency of the longitudinal vibration of the plate-shaped elastic vibrating body and the resonant frequency of the bending vibration having a vibration component substantially perpendicular to one surface of the elastic vibrating body are approximately the same. If they match, it is generally known that when an alternating voltage of the frequency is applied to an electrostrictive element fixed to an elastic vibrating body, longitudinal vibration and bending vibration are excited in the vibrating body.

The driving principle of the ultrasonic motor device in the present invention utilizes the above-mentioned effect, and one of the electrostrictive elements of a pair fixed to the elastic vibrator is 1lllf.
By doing this, longitudinal vibration and bending vibration are excited in the elastic vibrating body, and since these two vibrations coexist, elliptical motion is generated on the surface of the elastic vibrating body.

This elliptical motion is then transmitted to the motion extractor, and the motion extractor is driven in a fixed direction.

Furthermore, at least one pair of electrostrictive elements is fixed to the elastic vibrating body,
By exciting one of the pair of electrostrictive elements, the phase of the coupling between the longitudinal vibration and the bending vibration generated in the elastic vibrating body changes, and the driving direction of the motion extracting body can be controlled. be exposed.

That is, by switching the excitation position 1 of the plate-shaped elastic vibrating body, a 180 degree phase difference is generated in the combined phase of longitudinal vibration and bending vibration, and the elliptical motion generated on the surface of the elastic vibrating body is calculated. The direction of rotation can be switched between forward and reverse.

As mentioned above, in order to generate longitudinal vibration and bending vibration on an elastic vibrating body, it is necessary to approximately match the resonant frequencies for exciting both vibrations, and in order to match the resonant frequencies, For example, if longitudinal vibration and bending vibration occur in the length direction of the elastic vibrator, then the length and thickness of the plate-shaped elastic vibrator can be determined as shown in the following equation. .

That is, considering the resonant frequency ft that generates longitudinal vibration of vibration mode L1° (representing the lowest vibration mode) in the length ( ) direction of the elastic vibrating body, the resonant angular frequency ω, = From 2πfL, the resonance angular frequency is: (): length, Young's modulus.

Similarly, the resonant frequency f, which generates bending vibration in the length L) direction of the elastic vibrating body, is given by, and similarly, the resonant angular frequency ω, is given by (t; thickness ) is given by.

α is 5inll/2) eosh(a/2) + cos(a
/2) sinh(a/2) −〇 root, which corresponds to the order of the resonance mode of symmetrical bending vibration from the smallest order.

From the above, if ω, = ω, that is, the length ()) and thickness (χ) of the elastic vibrating body satisfy the relationship, the vibration mode of longitudinal vibration and the vibration mode of bending vibration coexist, as described above. Similarly, elliptical vibration is generated on the surface of the elastic vibrator.

In addition, when the directions of longitudinal vibration and bending vibration generated in an elastic vibrating body intersect approximately perpendicularly, the length () in the above equation can be replaced with the width (k') as appropriate, and ω, −ω , the relationship between increasing the length of the elastic vibrating body! ) Thickness ( ) Width (W') may be satisfied.

Next, when an elastic vibrating body has a vibration mode of longitudinal vibration and a vibration mode of bending vibration coexisting, control of the rotational direction of the elliptical motion generated on the surface of the body will be explained.

In the case of simple bending vibration, as shown in FIG. A driving force is generated in the direction of the arrow towards the nearby node.

Therefore, the driving force is distributed symmetrically about the midpoint and is independent of the position of the excitation source.

On the other hand, #I! In the case of vibration in which vibration and bending vibration coexist, if both ends of the vibrating body are open, the bending vibration will occur at the vibrating body 10.
Since G is considered to be symmetrical with respect to the midpoint in the longitudinal direction, two cases are possible: a case in which the longitudinal vibration is symmetrical with respect to the midpoint, and a case in which it is antisymmetrical. In Figures 12(a) and (b), if the displacement in the X direction (spreading direction) is x, and the displacement in the .

<1) X= a cos(k+x) cos(wt
) Y= b eos(ktx) sin(wt+d)
(2) X=m 5in(Lx) cos(wL)Y
=b cos(kzx) sin(wt+d)kl
, number of vibration modes of longitudinal vibration J + number of vibration modes of bending vibration -, angular frequency If the longitudinal vibration of formula (1) is symmetrical with respect to the midpoint in the longitudinal direction of elastic vibrator 100, then It can be seen that the points perform elliptical vibrations rotating in the same direction as the points. That is, unlike the case of simple bending vibration described above, it is possible to generate a driving force in the same direction at the point x and the point -X.

If the longitudinal vibration in equation (2) is antisymmetric with respect to the midpoint in the longitudinal direction of the elastic vibrating body 100, points X and -X on the flat plate perform elliptical vibration in opposite directions, and the driving force is directed in opposite directions. becomes.

Also, in both equations (1) and (2), each point is an elliptical vibration, so
The driving forces on the front and back sides of the elastic vibrating body 100 are opposite to each other, which is also different from the case of simple bending vibration.

In view of the above, an ultrasonic motor device driven by a single-phase power source and capable of forward and reverse rotation can be configured as follows.

■ When the driving forces at points X and -X are in the same direction (Fig. 12 (
In the case of a)) Assuming that the elastic vibrating body 100 has a vibration mode L26 of longitudinal vibration, for example, as shown in FIG. Place B. Assume that the driving force shown in Fig. 12 <a> is obtained by the excitation source A1
Next, if we consider the case of excitation by excitation source B, this is nothing but the case of excitation by excitation source A, which is rotated 180° with respect to the center line 0.
It is desirable to be able to obtain a driving force in the opposite direction to that of the motor.

In other words, the longitudinal vibration is symmetrical with respect to the midpoint in the longitudinal direction of the elastic vibrating body 100, and the number of nodes generated in the elastic vibrating body due to the resonance of the longitudinal vibration is an even number (for example, vibration modes L2°, L, etc.). mode, if the excitation source is installed at a symmetrical position with respect to the longitudinal midpoint on the same plane of the elastic vibrating body 100,
By selectively driving them one by one, the vibrating body 1
By controlling the combined phase of the longitudinal vibration and bending vibration generated at 00, it is possible to control the forward and reverse directions of the driving force.

■ When the driving forces at points X and -X are in opposite directions (Fig. 12 (
Case b) In this case, forward and reverse rotation control becomes possible with a configuration as shown in FIG. 12(b). That is, the elastic vibrating body 10G has a vibration mode L of longitudinal vibration. For example, as shown in Fig. 12(b), an excitation source A is placed at the node of longitudinal vibration that occurs to the left of the center line 0, and the surface facing the excitation source A is An excitation source B is placed at the position of the longitudinal vibration that occurs to the right of the center line 0. Assuming that the driving force shown in FIG. 12(b) is obtained by the excitation source A, the zero-order excitation source B
Considering the case of excitation by the
A driving force in the opposite direction to that shown in FIG. 6(b) is obtained.

In other words, the longitudinal vibration is antisymmetric with respect to the longitudinal midpoint of the elastic vibrating body 100, and the number of nodes generated in the elastic vibrating body due to the resonance of the longitudinal vibration is an odd number (for example, vibration modes L1°, L3°, etc.). In the vibration mode, longitudinal vibration excitation sources are provided on opposing surfaces of the elastic vibrating body 100, respectively! Then, by selectively driving one of them one by one, the combined phase of the longitudinal vibration and bending vibration generated in the vibrating body 100 can be controlled.
This means that the forward and reverse directions of the driving force can be controlled.

In the case of the above case (■), which is even worse, as shown in
In addition to the configuration shown in FIG. 1, the rotational direction of the elliptical vibration generated on the surface of the elastic vibrator can be controlled by the configuration shown in FIG. That is, electrostrictive elements 12m and 12b, which are excitation sources made of piezoelectric ceramic or the like, are placed at the nodes of longitudinal vibration occurring at the midpoint in the longitudinal direction of the elastic vibrating body 10 and on opposing surfaces of the elastic vibrating body 10, respectively. All you have to do is glue it on.

Each piezoelectric element 1 provided on opposing surfaces of the elastic vibrating body 10
By exciting either one of electrostrictors 2a and f2b, the bending vibrations generated by each electrostrictor 12aj2b have a phase difference of 180°.

In other words, the electrostrictive elements 12m and 12b cause in-phase longitudinal vibration (in-phase longitudinal vibration for deformation of the elastic vibrating body in the same direction).
occurs, but the phases of the coupled bending vibrations differ by 180°.

〔Example〕

Hereinafter, the ultrasonic motor device according to the present invention will be explained in detail based on the drawings.

FIG. 1 shows an embodiment of an ultrasonic motor device according to the present invention, in which electrostrictive elements 12 are provided on both sides of a plate-shaped elastic vibrating body 10.
m, 12b are fixed.

One end of lines 13m, 13b is connected to each electrostrictive element 12m, 12b, and the other end of these lines 13m, 13b is split into two parts 1, one of which is a switch mechanism serving as a first switching means. 14 terminals 14a, 1
4b, and the other end is connected to terminals 15m and 15b of a switch mechanism 15, which is a second switching means.

The line 13C has one end connected to the elastic vibration #lo and the other end connected to the ground.

The drive means 50 is connected to the switch 14C of the switch mechanism 14 by a line 13d.

The line 13e has one end connected to a peak hold circuit 62 that detects the alternating current voltage generated in the electrostrictive elements 12m and 12b, and the other end connected to the switch 15C of the switch mechanism 15. The peak hold circuit 62 is a reset circuit 6 that resets the detected value of the AC voltage continuously outputted from the electrostrictive element 12a or 12b at regular intervals.
4 constitutes a detection means 60.

Further, on the side of the elastic vibrating body 10 where the electrostrictive element 1.2m is provided, a motion extracting body 20 is arranged so as to be in direct contact with the elastic vibrating body 10.

The elastic vibrating body 10 is formed to have a length and thickness such that the resonant frequencies for exciting longitudinal vibration and bending vibration generated by each electrostrictive element 12m and 12b are approximately the same.

Each electrostrictive element 12a, 12b has a node of longitudinal vibration generated at the midpoint in the longitudinal direction of the elastic vibrating body 10.
The elastic vibrating body l is positioned approximately at the center of the longitudinal direction of b.
It is located on O.

The driving means 50 applies an alternating voltage of a specific frequency to one of the electrostrictive elements 12m and 12b by switching the switch 14c, thereby causing the elastic vibrator 10 to operate in a predetermined mode. It generates a longitudinal vibrator and bending vibration.

The driving means 50 includes a V-F conversion circuit 52 that converts the voltage value input from the voltage addition diagram I@76 into a specific frequency, and a waveform for making the output from the V-F conversion circuit 52 have a duty of 50%. It is composed of a shaping circuit 54 and a drive circuit 56.

The detection means 60 detects the AC voltage generated in either one of the electrostrictive elements 12m and 12b at regular intervals by switching the switch 15C.

The frequency variation means 70 is composed of an initial voltage setting circuit 72, an integration circuit 74, and a voltage addition circuit 76, and is for varying the voltage value inputted to the V-F conversion circuit 52. This is to vary the frequency of the alternating voltage applied to either the selected electrostrictive element 12a or 12b.

The initial voltage setting circuit 72 predetermines and holds the initial value of the voltage applied to the VF converter 52 from the voltage adding circuit 76, and is configured to set the resonant frequency that excites longitudinal vibration and bending vibration in the elastic vibrating body 10 or its resonance frequency. A constant voltage value is input to the voltage adding circuit 76 while holding a voltage value corresponding to a nearby frequency.

The integration circuit 74 continuously changes the voltage value input to the voltage addition circuit 76 in an upward or downward direction, and changes the voltage value input from the voltage addition circuit 76 to the V-F conversion circuit 52. electrostrictive element 12a or 12
This changes the frequency of the alternating voltage applied to b.

The peak hold means 80 is composed of a peak hold circuit 82 and a reset circuit 84, and the peak hold circuit 82 is connected to the cross 7! The reset circuit 84 is for storing the peak value of the lt pressure, and the reset circuit 84 is for resetting the storage contents of the peak hold circuit 82 based on a signal generated by a comparison circuit 94 of a comparison means 90, which will be described later.

The comparison means 90 is composed of sample and hold circuits 91 and 92, a voltage dividing circuit 93, and a comparison circuit 94.

The sample and hold circuit 111191 is an electrostrictive element t2m, 1 that is input to the peak hold circuit 62 of the detection means 60.
2b (hereinafter referred to as detected voltage) is input to the comparator circuit 94 at a predetermined timing, and the sample hold circuit 92 divides the peak voltage stored in the peak hold circuit 82 at a predetermined timing. circuit 9
3 to the comparison port j394.

The voltage dividing circuit 93 reduces the peak voltage stored in the peak hold circuit 82 to a predetermined voltage, and this reduced voltage (
(hereinafter referred to as a reference voltage) is input to the comparator circuit 94.

The ratio of pressure reduction is set to 2/3 to 374 with respect to the value of the peak voltage stored in the peak hold circuit 82.

The comparison port N94 compares the detection voltage input from the sample hold circuit 91 and the voltage divider circuit 93 with a reference voltage, and when the detection voltage becomes lower than the reference voltage, the signal is sent to the voltage increase/decrease control circuit 110. and to the reset circuit 84.

The voltage rise/fall control circuit 110 receives a signal from the comparator 94 and reverses the rise/fall direction of the voltage outputted from the integration circuit 74 while changing continuously in the rising direction or in the falling direction. The frequency of the alternating current applied to the electrostrictive elements 12a and 12b is limited within a certain range.

FIG. 2 is a perspective view of a portion of what is shown in FIG. 1.

Next, an ultrasonic motor device with the above configuration! The effect of this will be explained.

FIG. 5 shows vibration mode L. longitudinal vibration and vibration mode B,
. This shows a case in which bending vibration of the longitudinal vibration elastic vibrator in the same phase is generated by excitation of the electrostrictive element 12a or 12b by switching the switch 14C. For deformation of the elastic vibrating body in the same direction, in-phase longitudinal vibration will occur.
Depending on which of the electrostrictive elements 12a and 12b is excited, the phase of the generated bending vibration differs by 180°. Therefore, by selectively exciting the electrostrictive elements 12m and 12b, the direction of motion of the elliptical vibration generated on the surface of the elastic vibrating body 10 changes, and the directionality of the motion extracted to the motion extracting body 20 is changed. As shown by solid line arrows and broken line arrows in FIGS. 1 and 2, forward and reverse rotation is possible.

Therefore, if an object to be transported, such as a card or paper sheet, is brought into contact with the movement extractor 20, the object can be transferred in any direction by switching the switch 14C. Electrostrictive element 12b (12b) when an alternating current of constant voltage is applied and the applied frequency is changed.
It shows the relationship between the voltage V (amplitude of AC voltage) generated in a) and the frequency f, and particularly shows the relationship around the frequency f0 that excites longitudinal vibration and bending vibration in a predetermined mode.

Therefore, in the case of applying an alternating voltage to the electrostrictive element 12m, first of all, the initial voltage setting circuit 72 is set so that the voltage between 8-B-C shown in FIG. 3 is generated in the electrostrictive element 12b. Decide the voltage value to be set in advance.

In the embodiment, the voltage value from 273 to 374 of the peak voltage generated at the resonant frequency f0 is at least the electrostrictive element 1.
The initial voltage value is set so that 2b occurs.

Further, when the power is turned on and application of an alternating voltage to the electrostrictive element 12a is started, the voltage output from the integrating circuit 74 is set in the rising direction or the falling direction, and the voltage value input to the V-F conversion diagram 852 is set. so that it rises or falls continuously.

That is, the input voltage to the V-F conversion circuit is the sum of the initial voltage of the initial voltage setting circuit 72 and the variation caused by the integrating circuit 74.

Therefore, the frequency of the alternating voltage applied from the driving means 50 to the electrostrictive element 12a is varied by the frequency varying means 70, and the excitation state of the elastic vibrating body 10 is also varied according to the varying frequency.

At this time, the voltage generated in the electrostrictive element 12b is transferred to the switch 1.
5c to the terminal 15b side, when the integrating circuit 74 outputs a voltage value in the rising direction and the initial applied frequency to the electrostrictive element 12m (when excitation of the elastic vibrating body 10 is started). , the frequency of the alternating voltage applied from the driving means 50 to the electrostrictive element 12a) is the frequency f shown in the third section.
When it is on the A point side from 0, the frequency f increases continuously, so the voltage V increases from around the A point toward the B point (peak value).

As the voltage ■ increases, the voltage division diagram! The reference voltage output from @93 also increases from Dl to D2.

At this time, the peak value stored in the peak hold circuit 'n82 is also updated as the voltage V rises.

Also, at this time, the voltage value output from the sample and hold circuit 91 and the sample and hold circuit 92 is
Since the reference voltage from the sample and hold circuit #g92 outputted via the reference voltage is lower, no signal is generated from the comparator circuit 94.

When the frequency f further increases and the voltage V starts to fall from the peak point B to the zero point, the reference voltage input from the voltage divider circuit 93 to the comparator circuit 94 is fixed at the level of . That will happen.

On the other hand, when the applied frequency increases to a frequency at which the detection voltage output from the sample and hold circuit 91 becomes 6 points or less, the comparison circuit 94 detects that the detection voltage has become below the reference voltage and generates a signal. do.

The voltage rise/fall control circuit 110 receives the signal from the comparison circuit n94 and controls the output voltage of the integration circuit 74 from the rising direction to the falling direction.

As a result, the frequency of the alternating voltage output from the V-F conversion circuit 52 and applied to the electrostrictive element 128 decreases.

Further, the signal from the comparison circuit 94 is transmitted to the reset circuit 84.
The reset circuit 84 is output to the peak hold circuit 8.
Reset the peak value held in 2. As a result, the reference voltage output from the voltage dividing circuit 93 also drops to the level of Dl.

Depending on the frequency that started falling, the detected voltage and the reference voltage will rise to point B, as in the case of the frequency rise described above, and after passing point B, only the detected voltage will fall until point A, so that the detected voltage becomes the reference voltage. When the frequency reaches point A where it becomes less than the voltage, the comparator circuit 94. The voltage increase/decrease control circuit 110 again switches the voltage output from the integrating circuit 74 from the decreasing direction to the increasing direction.

Similar operations will be repeated thereafter.

In addition, if the initial frequency applied to the electrostrictive element 12a is on the point A side from frequency 10 in the same machine as above, and the integrating circuit 74 outputs a voltage value in the downward direction, the frequency f continuously decreases. As a result, the voltage V decreases from, for example, near point A toward point B in the opposite direction.

At this time, the reference voltage output from the voltage dividing circuit N93 is D
When the detection voltage output from the sample and hold circuit 91 falls below the reference voltage, the comparison circuit 94 issues a signal to lower the voltage output from the integration circuit 74, as described above. Reverse the direction from the upward direction. Thereafter, the electrostrictive element 12 is
The voltage generated at b is controlled between -B and C in FIG.

Similar control is executed when the initial frequency applied to the electrostrictive element 12a is closer to point B than the frequency f0 shown in FIG.

FIG. 6 shows vibration mode L. Longitudinal vibration and vibration mode B2
This is an example showing a case where 0 bending vibration is occurring,
The longitudinal vibration node portion is located approximately at the longitudinal center of the electrostrictive element. Further, FIGS. 7 to 10 show the case where longitudinal vibration of vibration mode L+o and bending vibration of vibration mode B4° are occurring, and the pair of electrostrictive restraints 12a12b are caused by elastic vibration. The eighth embodiment shows an embodiment in which the elastic vibrating body 10 is provided on the same surface of the body 10 and is provided at positions including longitudinal vibration nodes that occur at substantially symmetrical positions with respect to the midpoint in the longitudinal direction of the elastic vibrating body 10. The figure shows a case where longitudinal vibration of vibration mode L4° and bending vibration of vibration mode Bi are occurring, and two electrostrictive element pairs 12a, 12b, 12
Similar to the seventh section, a'J2b'' includes nodes of longitudinal vibration that occur on the same surface of the elastic vibrating body 10 at substantially symmetrical positions with respect to the midpoint in the longitudinal direction of the elastic vibrating body 10. FIG. 9 shows an embodiment provided in the vibration mode L.

longitudinal vibration and vibration mode B. When a bending vibration of An example is shown in which the device is installed at a position including a node of longitudinal vibration occurring at position 1,
Figure 10 shows vibration mode L. longitudinal vibration and vibration mode B
When a bending vibration of 4° is occurring, two pairs of electrostrictive elements 12m, 12b, 12a', 12b' are arranged on opposite surfaces of the elastic vibrating body 10, as in FIG. An embodiment is shown in which the vibration plate is provided at a position that includes nodes of longitudinal vibration that occur at positions that are approximately symmetrical with respect to the midpoint in the longitudinal direction.

FIGS. 4(a), (b), and (c) show an embodiment of an ultrasonic motor device having a more concrete structure. A vibrating body support member 32 made of rubber is fixedly provided.

The elastic vibrating body 10 having electrostrictive elements 12m and 12b attached to the upper and lower surfaces thereof is placed on the vibrating body support member 32 with the electrostrictive element 12b located in the recess 32a.

As the elastic vibrating body lO, the dimensions are 40.8 (+++++) x
Using 5US416 board of 8 [m garden] x 15 (as),
Electrostrictive elements 12a and 12b are placed on the center of this 5US416 plate.
As, the dimensions are 24(am) x8(m+e) xo,
5 (Peng-) PTZ board is attached.

A pair of arms 36m and 36b are provided at one end of the stand 30, one end of which is rotatably supported on the stand 30 by a shaft 34, and the other ends of the arm 361I and the arm 36b are connected by a spring support member. Arm 36m
The arm 36 and the arm 36 can be rotated together. A motion extractor support shaft 40 is passed through the intermediate portion of the arms 36a and 36b, and the movement extractor support shaft 40 is inserted between the arms 36a and 38b.
A roller-shaped motion extracting body 20 is rotatably supported between the two.

The pressure spring 42, which is a pressure means, has one end locked to the end surface of the stand 30, and the other end locked to the spring support 3.
8, the stand 30 and the arm 36a,
36b, so that the motion extracting body 20 is constantly pressed against the elastic vibrating body 10.

What is the positional relationship between the elastic vibrating body 10 and the motion extracting body 20?
As shown in Figure (C), the motion extractor 20 is an elastic vibrator l.
When the elastic vibrator 10 on the convex portion 32b of the vibrator support member 32 is pressurized by the pressure spring 42 on the
It is located at the top.

A pulley 44 is integrally attached to a portion of the motion extractor support shaft 40 that protrudes outward from the arm 36&.

In the above embodiment shown in FIG. 4 (aHbHc), the drive means, detection means switch mechanism, etc. are appropriately arranged in the same manner as in the embodiment shown in FIG. 1, and illustration thereof is omitted. It is.

Although not particularly illustrated, the shape of the motion extractor is not limited to that described in each of the above embodiments.
Of course, it may be a hemispherical body or the like, and any shape that can extract the elliptical vibration generated on the surface of the elastic vibrating body is sufficient.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

When detecting the vibration state of the elastic vibrating body, one of the pair of electrostrictive elements fixed to the elastic vibrating body, which is not supplied with power, was used for pressure detection. There is no need to separately provide an electrostrictive element, electrodes, etc. as means for detecting the vibration state of the vibrating body.

In addition, when applying an alternating voltage to either one of the electrostrictive elements to excite longitudinal vibration and bending vibration in a predetermined mode, it is possible to apply an alternating current at the optimum driving frequency to this electrostrictive element, and the elastic vibration It is possible to keep the vibration state of the body in a good state at all times.

Furthermore, even when an alternating voltage is selectively applied to a pair of electrostrictive elements to excite longitudinal vibration and bending vibration in a predetermined mode, an alternating current at an optimum drive frequency is applied to each of the electrostrictive elements. This makes it possible to control the vibration state of the elastic vibrator in a well-balanced manner.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing one embodiment of the present invention, FIG. 2 is a perspective view of a part of what is shown in FIG. 1, FIG. 3 is a diagram showing the relationship between detected voltage and frequency, and FIG. )(b)(C) show other embodiments of the present invention, FIG. 4(a) is a plan view, FIG. 4(b) is a side view, and FIG. 4(e) is an arm pulley and pressure spring. Side view with removed, Figure 1 from Figure 5
Figure 0 is an explanatory diagram showing the generation state of longitudinal vibration and bending vibration according to the present invention, Figure 11 is an explanatory diagram showing the driving direction by bending vibration, and Figures 12 (a) and (b) are diagrams showing the generation state of longitudinal vibration and bending vibration. FIG. 3 is an explanatory diagram showing driving directions caused by both vibrations. Symbol Explanation

Claims (7)

[Claims] 1. A plate-shaped elastic vibrating body excited with longitudinal vibration in a predetermined mode and bending vibration in a predetermined mode; at least one pair of electrostrictive elements fixed to one surface or opposing surfaces of the elastic vibrating body; a driving means for applying an alternating voltage of a specific frequency to cause both the longitudinal vibration and the bending vibration in the elastic vibrating body, and switching the alternating voltage of the frequency to one of the pair of electrostrictive elements; a first switching means for applying voltage to the electrostrictive element; a detecting means for detecting a voltage generated in the electrostrictive element; and a second switching means for switching and connecting the detecting means to one of the pair of electrostrictive elements. and at least one motion extracting body that contacts the elastic vibrating body at a position that substantially excludes nodes of the longitudinal vibration and the bending vibration generated in the elastic vibrating body. Sonic motor device. 2. A plate-shaped elastic vibrating body excited with longitudinal vibration in a predetermined mode and bending vibration in a predetermined mode; at least one pair of electrostrictive elements fixed to one surface or opposing surfaces of the elastic vibrating body; a driving means for applying an alternating voltage of a specific frequency to one of them to cause both the longitudinal vibration and the bending vibration in the elastic vibrating body; at least one motion extractor that contacts the elastic vibrator at a position substantially excluding nodes of bending vibration; and at least one motion extractor that is connected to the drive means and that changes the frequency applied to the electrostrictive element in an upward direction or a downward direction. a frequency varying means for varying the frequency; a detecting means for detecting the voltage generated in either one of the electrostrictive elements; a peak holding means for holding the peak value of the detected voltage detected by the detecting means; and the peak value. a comparison means for comparing a reference voltage generated by dividing the voltage with the detected voltage and generating a predetermined signal when the detected voltage becomes equal to or lower than the reference voltage; and a comparison means for generating a predetermined signal based on the signal. 1. An ultrasonic motor device comprising means for inverting and controlling the direction of frequency fluctuation. 3. 3. The ultrasonic motor device according to claim 2, wherein the peak value held by the peak hold means is reset by the signal from the comparison means. 4. 3. The ultrasonic motor device according to claim 1, wherein the motion extractor comprises rotatable roller means. 5. The electrostrictive elements are configured as a pair, and the electrostrictive elements are respectively disposed on opposing surfaces of the elastic vibrating body, and the electrostrictive elements are configured to suppress the longitudinal vibration generated at the midpoint in the longitudinal direction of the elastic vibrating body. 3. The ultrasonic motor device according to claim 1, wherein the ultrasonic motor device is provided opposite to a position including a node. 6. 3. The pair of electrostrictive elements are provided at positions including nodes of the longitudinal vibration occurring at symmetrical positions with respect to the longitudinal midpoint of the elastic vibrating body. ultrasonic motor device. 7. a first switching means that switches and applies an alternating current of the frequency to one of the pair of electrostrictive elements; and a first switching means that switches and connects the detection means to one of the pair of electrostrictive elements. 3. The ultrasonic motor device according to claim 2, further comprising a second switching means for controlling the ultrasonic motor.