JPH08191575A - Vibration device - Google Patents

Abstract

PURPOSE: To provide a vibration device of, for example, an ultrasonic motor for detecting the vibration state of a vibration element. CONSTITUTION: In a vibration device with a vibration element for forming a flat plate shape for forming elliptical motion at motion extraction bodies 3a and 3b by synthesizing two vibration modes which are excited by applying a drive signal to a vibrator provided on the surface of a vibration elastic body, a vibrator for drive is provided at the single-surface side of the vibration elastic body and a vibrator for detecting the vibration state of a motion extraction body is provided on the other surface side of the vibration body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration device such as an ultrasonic motor and, more particularly, to a flat plate vibration element.

[0002]

2. Description of the Related Art An ultrasonic motor is known as one of the typical vibration devices, and various ultrasonic motors have been proposed by paying attention to a vibrating element in which vibration for driving is formed. ing. FIG. 7 shows, for example, JP-A-63-2.
90176, JP-A-63-294269, JP-A-1
No. 110070 and Japanese Patent Application Laid-Open No. 1-110071, the vibration element V is formed in a flat plate shape in the ultrasonic motor shown in FIG.

This vibrating element V is B shown in FIG. 8 (b).
By combining the bending vibration of the mode and the longitudinal vibration of the L mode shown in FIG. 8C, the driving pieces 3a and 3b forming the motion extractor, which are provided at the antinode of the bending vibration of the B mode, are formed as shown in FIG. An elliptic motion is performed as shown in (a).

The vibrating element V is arranged between the upper wall 9 and the lower wall 10, and the rollers 8a, 8 are provided at the lower end from the upper wall 9.
Roller bars 6a, 6b having b are provided.

On the other hand, in the vibrating element V, the support body 4 is fitted in the hole portion of the lower wall 10, is elastically supported by the spring 7 arranged in the hole portion, and is moved upward by the rollers 8a and 8b. The drive pieces 3a and 3b of the vibrating element V are pressed into contact with the moving body 5 which is restricted and is allowed to move in the x direction. Then, the moving body 5 moves in the x direction by the friction driving force generated by the elliptic movement formed on the driving pieces 3a and 3b.

The vibrating element V in which such B-mode and L-mode vibrations are formed forms a vibrator on both surfaces of a rectangular flat plate-shaped ground electrode plate 2, as shown in FIG. 7B. A pair of driving piezoelectric elements 1a, 1b and 1c, 1d
Are bonded and fixed, and these driving piezoelectric elements 1a, 1
b, 1c, and 1d are polarized in the thickness direction as shown in FIG. 9A, and the polarization direction is the direction indicated by the arrow.

As shown in FIG. 9 (a), the bending vibration in the B mode is caused by the piezoelectric elements 1a and 1 which are polarized in the thickness direction.
By applying the B input to d and the A input which is an electric field having a polarity opposite to that of the A input to the piezoelectric elements 1b and 1c, for example, an electric field of the B input is applied as shown in FIG. 9B. The piezoelectric elements 1 (a) and 1d are expanded, the piezoelectric elements 1b and 1c to which the electric field of A input is applied are contracted, and this expansion / contraction operation is alternately repeated.

Further, the longitudinal vibration of the L mode is generated by applying an electric field of the same polarity to all of the piezoelectric elements 1a, 1b, 1c, 1d shown in FIG.
It is formed by expanding and contracting as in (d).

Here, when the resonance frequencies of the two vibration modes of the vibrating element V, that is, the B mode and the L mode, are present close to each other, both vibratory modes are simultaneously excited by exciting the vibrator at the resonance frequencies. appear. Also, FIG.
As shown in 0, a sin wave with a phase difference of 90 degrees, co
The s wave is used as the A input and the B input, and the phase of the B mode and A mode vibrations is shifted by 90 degrees, so that the driving piece makes an elliptical motion, and the moving piece is driven by frictional contact with the moving body. be able to. In FIG. 10, ◯ indicates contraction, ● indicates extension, ◇ indicates bending, and ◆ indicates bending.

[0010]

However, in the above-described conventional vibration device, it is judged whether or not the moving body 5 is driven well, that is, whether or not the B mode and L mode vibrations are appropriately performed. There is nothing but actual measurement of the vibration of the vibration element V, and although the torque and efficiency of the ultrasonic motor greatly change depending on the input frequency, the frequency control for obtaining the optimum characteristics is experimentally performed by the frequency control. Was changed so that it would be obtained each time.

The B-mode and L-mode vibrations are
It is driven at a resonance frequency that is a value (first-order or second-order, third-order ...) Based on the natural frequency of the vibrator in each of these modes, but there is a shift in the resonance point due to environmental conditions such as temperature and humidity. , The same driving force cannot be obtained even if they are driven at the same frequency.

An object of the invention according to the present application is to provide a vibrating device capable of detecting the vibration state of a vibrator.

[0013]

A first structure for achieving the object of the invention according to the present application is, as described in claim 1, a drive signal for a vibrator provided on the surface of a vibrating elastic body. In a vibrating device having a flat plate-shaped vibrating element that forms an elliptical motion in a motion extractor by combining two vibration modes excited by applying a vibration, a vibrator for driving is provided on one side of the vibrating elastic body. And a vibration detecting vibrator for detecting the vibration state of the motion extractor is provided on the other surface side of the vibrator.

With this configuration, the vibration state of the motion extractor such as the driving piece can be detected even in the flat plate-shaped vibrating element, and the drive control of the vibrating element can be performed using the optimum frequency.

A second configuration for achieving the object of the invention according to the present application is excited by applying a drive signal to a vibrator provided on the surface of a vibrating elastic body as described in claim 2. In a vibrating device having a flat plate-shaped vibrating element that forms an elliptical motion in a motion extractor by combining two vibration modes, drive vibrators are provided on both surfaces of the vibrating member.
According to another aspect of the present invention, there is provided an oscillating device characterized in that a part of a vibrator on one side corresponding to the motion extractor is a vibrator for detecting a vibration state of the motion extractor.

With this structure, since the area of the driving vibrator can be made large, the amplitudes of the two vibration modes for driving can be increased and the driving torque can be increased, while The vibration of the motion extractor can be detected without increasing the number of vibration detecting oscillators such as piezoelectric elements.

A third configuration for achieving the object of the invention according to the present application is, as described in claim 3, in claim 1 or 2, wherein the motion extractor is the maximum amplitude position of the standing wave of the driving vibration. In the vibration device, the vibration detecting oscillator is provided at a position that is an integral multiple of a half wavelength of the standing wave with reference to the motion extractor.

In this structure, since the vibration detecting oscillator is arranged at the trough or the peak position of the vibration, the vibration of the motion extractor can be accurately detected.

A fourth object of realizing the object of the invention according to the present application is, as described in claim 4, in claim 1.
The vibration detecting oscillator has a size substantially the same as that of the motion extractor.

With this configuration, only the vibration state of the motion extractor can be accurately detected.

[0021]

【Example】

(First Embodiment) FIGS. 1 and 2 show a first embodiment of the present invention.

FIG. 1 shows a ground electrode plate 12, piezoelectric elements 11a, 11b, 15a, 15b and driving pieces 13a, 13.
b, a perspective view of a rectangular flat plate-shaped vibrating element composed of the support body 4, and the appearance and polarization processing of the respective piezoelectric elements are the same as those of the conventional vibrating element shown in FIG.

However, in this embodiment, a sin wave and a cos wave to the pair of piezoelectric elements 11a and 11b fixed to one side of the ground electrode plate 12 which also functions as a vibration elastic body, or a rectangular shape whose phase is shifted by 90 degrees. The A and B inputs of a drive signal such as a wave excite the bending vibration of the B mode shown in FIGS. 2A and 2B and the longitudinal vibration of the L mode.

That is, in the conventional example shown in FIG. 9, all the piezoelectric elements 1a to 1d are used for driving, but in the present embodiment, the piezoelectric elements 11a and 11b on one side are used for driving and the other surface is used. The piezoelectric elements 11c and 11d on the side are used to detect the vibration state of the driving pieces 13a and 13b.

The driving principle of the vibrating element of this embodiment is the same as the driving principle of the vibrating element in the conventional example shown in FIG. 9 described above, and for example, a sin wave is used as the A and B inputs of the pair of piezoelectric elements 11a and 11b. When a cos wave drive signal is applied, bending vibration and longitudinal vibration are simultaneously excited in the piezoelectric elements 11a and 11b, as shown in FIG.

Therefore, the vibrating element of this embodiment includes the driving piece 13a provided on the piezoelectric element 11a and the piezoelectric element 11b.
The driving piece 13b provided above makes an elliptic motion as shown in FIG. Here, the vibrator of this embodiment is elastically supported by the spring 7 or the like as in the conventional example of FIG. 7,
It makes pressure contact with the moving body 5.

On the other hand, the pair of piezoelectric elements 15a and 15b adhered and fixed to the other surface side of the ground electrode plate 12 are for detecting the vibration of the driving pieces 13a and 13b, and the piezoelectric element 15a outputs the A output as the driving piece 13a. And the piezoelectric element 15b outputs the vibration state of the driving piece 13b as B output.

Here, when a signal for extending the thickness direction of the piezoelectric element 11a is input to the A input of the piezoelectric element 11a, the length direction of the piezoelectric element 11a shrinks, and the electrode plate 12 is moved to the electrode plate 12 of FIG.
Can be bent like. As a result, the vibration detecting piezoelectric element 15a is bent so as to extend in the longitudinal direction, and the electrode plate 12 is bent.
And a potential difference is generated between the piezoelectric element 15a and the surface of the vapor deposition electrode of the piezoelectric element 15a, and the piezoelectric element 15a contracts in the thickness direction. In addition, the piezoelectric element 11a
When a signal for contracting the thickness direction of the piezoelectric element 11a is input to the A input of, the length direction of the piezoelectric element 11a extends and the electrode plate 1
2 is bent as shown in FIG. As a result, the vibration detecting piezoelectric element 15a is bent so as to contract in the length direction, a potential difference is generated between the electrode plate 12 and the vapor deposition electrode surface of the piezoelectric element 15a, and the piezoelectric element 15a extends in the thickness direction.

As a result, the vibration of the piezoelectric element 11a and the phase of the A output signal are detected 180 degrees out of phase. Similarly, the vibration of the piezoelectric element 11b and the phase of the B output are detected 180 degrees out of phase.

The piezoelectric element 15a thus detected
A detection signal of A output by the piezoelectric element 15b and a detection signal of B output by the piezoelectric element 15b are input to a driving circuit (not shown) as a vibration state detection signal of the driving piece 13a and the driving piece 13b, and are combined with characteristics as an actual motor. For example, the output signal at the time when the torque is maximized can be stored by changing the frequency. Further, when the appropriate frequency changes due to the influence of temperature and humidity, the optimum driving frequency in different environments can be known in advance, and thus optimum driving can be performed. Furthermore, optimum frequency control can be performed by comparing with previously stored data such as frequency-torque characteristics, temperature-frequency characteristics, humidity-frequency characteristics, and the like.

(Second Embodiment) FIG. 4 shows a second embodiment of the present invention.

In the above-described first embodiment, the vibrating element does not always expand or contract as shown in FIG. 2, and as shown in FIG. Driven in the bending mode in the state where there is elongation as shown by and contraction as shown by. Therefore, the vibration detecting piezoelectric elements 15a and 15b detect signals including components of vibration modes other than the vibration of the driving pieces 33a and 33b.

Therefore, in this embodiment, as shown in FIG.
The vibration detecting piezoelectric element 35a and the vibration detecting piezoelectric element 35b are provided on the other surface side of the ground electrode plate 32 facing the driving pieces 33a and 33b in substantially the same area and at the same position.

That is, in the second embodiment, the piezoelectric elements 35a, 35 have substantially the same area as the driving pieces 33a, 33b.
Since b is formed, the piezoelectric element 35a for vibration detection,
In the vibration detecting piezoelectric element 35b, the signal output level is proportional to the area of the piezoelectric element and thus is smaller than that in the first embodiment, but only the vibration state of the driving pieces 33a and 33b can be accurately detected.

As shown in FIGS. 5 (c) and 5 (d), piezoelectric elements 35a and 35b for vibration detection are provided from the position of the driving piece to a position that is an integral multiple of the half wavelength of the B-mode standing wave. Even if provided, since the vibration detecting piezoelectric elements 35a and 35b are present at the antinode position or the valley position of the B mode, the same effect can be obtained. In this case, the same phase as the drive signal of the piezoelectric elements 31a and 31b or The detection signal is output in the opposite phase.

(Third Embodiment) FIG. 6 shows a third embodiment.

In the above-described first and second embodiments, the driving piezoelectric elements 11a, 11b, 31a, 31 are used.
b is only half the area of the piezoelectric element for driving each mode of the conventional example shown in FIG. 7, and when driven at the same voltage, the amplitude is smaller in the first and second embodiments, and therefore the drive torque Will be greatly reduced. Therefore, although a sufficient torque can be obtained by combining the second embodiment described above with the conventional example of FIG. 7, an extra piezoelectric element is required.

This embodiment is similar to the conventional example shown in FIG.
Piezoelectric elements 41, 42, 44 and 45 for forming L-mode and B-mode vibrations are adhered and fixed on both surfaces of the ground electrode plate 43, and driven in the same manner as in the conventional example of FIG. , The piezoelectric element 44, as shown in FIG.
Piezoelectric element part 44a for forming L-mode and B-mode drive vibrations and piezoelectric element part 4 for detecting vibration of driving piece 40a.
4b, and the piezoelectric element 45 is L
Element 45a for forming driving vibrations in the B mode and the piezoelectric element portion 45 for detecting vibration of the driving piece 40b
and b. Specifically, the piezoelectric element 4
By dividing the vapor deposition electrodes formed on the surfaces 4 and 45 into a drive electrode surface and a detection electrode surface, a drive piezoelectric element and a vibration detection piezoelectric element are formed from one piezoelectric body. are doing. Then, the piezoelectric element portions 44b and 45b for vibration detection
Is provided at a position facing the driving pieces 40a and 40b.

In each of the embodiments described above, the elliptical motion shown in FIG. 8A is formed in the driving piece by combining the B mode which is a bending vibration and the L mode which is a longitudinal vibration. The elliptical motion may be formed in the plane of the vibrator by combining bending vibrations in the two directions.

[0040]

According to the invention described in claim 1, it becomes possible to detect the vibration state of the motion extractor such as the driving piece even in the flat plate-shaped vibrating element, and the vibrating element of the vibrating element can be detected by using the optimum frequency. Drive control can be performed.

According to the second aspect of the present invention, since the area of the driving vibrator can be widened, the amplitudes of the two vibration modes for driving can be increased and the driving torque can be increased. While having the advantage that the vibration of the motion extractor can be detected without increasing the number of vibration detecting oscillators such as piezoelectric elements.

According to the third aspect of the invention, since the vibration detecting vibrator is arranged at the valley or peak position of the vibration,
The vibration of the motion extractor can be accurately detected.

According to the invention described in claim 4, only the vibration state of the motion extractor can be accurately detected.

[Brief description of drawings]

FIG. 1 is a perspective view of a vibration element showing a first embodiment of a vibration device according to the present invention.

FIG. 2 is a diagram showing vibration of the vibration element of FIG. 1 and a state of vibration detection.

3 is a perspective view showing a vibrating state of the vibrating element of FIG. 1. FIG.

FIG. 4 shows a second embodiment, (a) is a side view of the vibrating element, and (b) is a back view of (a).

5 shows the relationship between the vibration element of FIG. 4 and a standing wave, (a)
Is a side view of the vibrating element, (b) is a waveform diagram showing the position of the vibration detecting piezoelectric element with one standing wave, and (c) is the position of the vibration detecting piezoelectric element with two standing waves. Waveform diagram showing (d)
FIG. 3 is a waveform diagram showing the position of the vibration detecting piezoelectric element in three standing waves.

FIG. 6 shows a third embodiment, (a) is a side view of the vibrating element, and (b) is a back view of (a).

FIG. 7 shows a conventional ultrasonic motor, (a) is a side view,
(B) is a perspective view of the vibration element of (a).

FIG. 8 is a diagram showing a driving principle of the vibration element of FIG. 7, (a)
Is a side view of the vibrating element, (b) is a waveform diagram of a B-mode standing wave, and (c) is a waveform diagram of an L-mode standing wave.

FIG. 9 is a diagram showing a polarization direction of a piezoelectric element and a principle of forming a vibration mode.

10 is a waveform diagram of a voltage applied to the vibration element in FIG.

[Explanation of symbols]

11a, 11b, 31a, 31b, 44a, 45a Driving piezoelectric element 12 Ground electrode plate 13a, 13b, 33a, 33b, 40a, 40b Driving piece 14 Piezoelectric element support 15a, 15b, 44b, 45b Vibration detecting piezoelectric element

Claims (4)

[Claims] 1. A flat plate-shaped vibrating element for forming an elliptical motion in a motion extractor by combining two vibration modes excited by applying a drive signal to a vibrator provided on the surface of a vibrating elastic body. In a vibrating device having a vibrating elastic body, a driving vibrator is provided on one side of the vibrating elastic body, and a vibration detecting vibrator for detecting a vibrating state of the motion extractor is provided on the other side of the vibrating elastic body. A vibrating device characterized in that. 2. A vibrating element having a flat plate shape for forming an elliptic motion in a motion extractor by combining two vibration modes excited by applying a drive signal to a vibrator provided on the surface of the vibrating elastic body. In a vibrating device having: a vibrator for driving is provided on both sides of the vibrating body, and a part of the vibrating body on one side corresponding to the motion extracting body is vibrated for detecting a vibration state of the motion extracting body. A vibrating device characterized by being a child. 3. The motion extractor according to claim 1 or 2, wherein the motion extractor is provided at a maximum amplitude position of the standing wave of the driving vibration, and the vibration detecting oscillator is used as a reference for the motion extractor. A vibrating device, which is provided at a position that is an integral multiple of a half wavelength. 4. The vibration device according to claim 1, wherein the vibration detecting oscillator has substantially the same size as the motion extractor.