JP3406948B2 - Vibration device - Google Patents

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. 7, for example JP-63-
No. 290176, JP 63-294269, JP-A-1-110070, the public JP 1-110071
The ultrasonic motor proposed in the report is shown, and the vibration element V is formed in a flat plate shape.

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.
d to the B input by the said B input is applied the A input is reverse polarity electric field to the piezoelectric elements 1b and 1c, as shown in (b) of FIG. 9, for example, the electric field of the B input is applied the piezoelectric element 1 a and 1d are extended, the piezoelectric elements 1b and 1c to electric field a input is applied to shrink, is formed by repeating the stretching operation alternately.

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. Occur. 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]

Means for Solving the Problems and action] The purpose of the
To achieve the present invention, in the present invention, a vibrator provided on the surface of a vibrating elastic body, and a motion extractor provided on the surface of the vibrator.
A vibrating elastic body having a flat plate-shaped vibrating element for forming an elliptic motion in the motion extractor by combining two vibration modes excited by applying a drive signal to the vibrator. an oscillator for driving provided on one side of the same position as the definitive motion extraction member on the other side of the vibrating elastic member
In it is provided with a vibration detection vibrator for detecting the vibration state of the motion extraction member has a substantially same area as the motion extraction member.

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

EXAMPLES ( Reference Technique Example ) FIGS. 1 and 2 show a reference technique example of the present invention.

FIG. 1 shows a ground electrode plate 12 and a vibrator.
And piezoelectric elements 11a of, 11b, 15a, 15b, motion
FIG. 7 shows a perspective view of a rectangular flat plate-shaped vibrating element composed of drive pieces 13a and 13b as extractors and a support 14 and FIG.
It is assumed that the external appearance and the polarization treatment and polarization direction of each piezoelectric element are the same as those of the conventional vibration element shown in FIG.

However, in this reference example , the sin wave and the cos wave are applied to the pair of piezoelectric elements 11a and 11b which are bonded and fixed to one side of the ground electrode plate 12 which also functions as the vibration elastic body.
Alternatively, A of a drive signal such as a rectangular wave whose phase is shifted by 90 degrees,
The B input excites the bending vibration of the B mode shown in FIGS. 2A and 2B and the longitudinal vibration of the L mode described above.

[0024] That is, in the conventional example shown in FIG. 9 utilizes all of the piezoelectric elements 1a~1d to the drive, the reference
In the technical example , the piezoelectric elements 11a and 11b on one side are used for driving, and the piezoelectric elements 115a and 15b on the other side are used for driving.
It is used to detect the vibration states of 3a and 13b.

The driving principle of the vibrating element of this reference technology example is the same as the driving principle of the vibrating element in the conventional example shown in FIG. 9 described above. For example, a sin wave is used as the A and B inputs of the pair of piezoelectric elements 11a and 11b. When a drive signal of a cosine wave 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 reference example is
Driving piece 13a provided on piezoelectric element 11a and piezoelectric element 1
The driving piece 13b provided on the 1b makes an elliptic motion as shown in FIG. Here, the vibrating element of this reference technology example is elastically supported by the spring 7 or the like as in the conventional example of FIG. 7, and comes into 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.

[0031] (First Embodiment) FIG. 4 shows a first embodiment of the present invention.

In the above-mentioned reference technology example , the vibrating element does not always extend or contract as shown in FIG. 2, and as shown in FIG. It is driven in the bending mode in the state where there is elongation and contraction as shown by. for that reason,
From the piezoelectric elements 15a and 15b for vibration detection, the driving piece 33
A signal including a component of a vibration mode other than the vibrations of a and 33b is detected.

[0033] In this embodiment therefore, as shown in FIG. 4,
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 this embodiment, for ground
On the other side of the electrode plate 32 (that is, the other side of the vibrating elastic body)
Since the piezoelectric elements 35a and 35b are formed at substantially the same positions as the driving pieces 33a and 33b in the driving pieces 33a and 33b, the vibration detecting piezoelectric elements 35a and the vibration detecting piezoelectric elements 35b are Since the signal output level is proportional to the area of the piezoelectric element and is smaller than that of the reference technology example , 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.

( Second Embodiment) FIG. 6 shows a second embodiment.

[0037] In the first embodiment described above, the piezoelectric element 11a for driving, 11b, 31a, 31b is not only half the area of the piezoelectric element for driving the respective modes of the conventional example shown in FIG. 7, it is small amplitude is driven at the same voltage first embodiment, hence the drive torque is greatly reduced. Therefore, a sufficient torque can be obtained by combining the first embodiment described above with the conventional example of FIG. 7, but 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 generating driving vibrations of the B mode and the B mode, and a 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 piezoelectric element for driving and a piezoelectric element for detecting vibration are formed from one piezoelectric body. is doing. Then, the piezoelectric element portions 44b and 45b for vibration detection
The drive pieces 40a, 40b facing the drive pieces in the same position
It is provided so as to have approximately the same area as 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]

As described above, according to the present invention,
At the same position as the motion extractor on the other side of the vibrating elastic body,
A vibration detection oscillator having the same area as this motion extractor
Since it is provided, only the vibration state of the motion extractor can be accurately detected.
Can be issued .

[0041]

[0042]

[0043]

[Brief description of drawings]

FIG. 1 is a perspective view of a vibration element showing a reference technology example 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.

4A and 4B show a first embodiment according to the present invention, FIG. 4A is a side view of a vibrating element, and FIG. 4B is a rear view of FIG. 4A.

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.

6A and 6B show a second embodiment according to the present invention, in which FIG. 6A is a side view of a vibrating element, and FIG. 6B is a rear view of FIG.

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, 41, 42, 44
a, 45a Driving piezoelectric element 12 , 32, 43 Ground electrode plates 13a, 13b, 33a, 33b, 40a, 40b Driving piece 14 Piezoelectric element support 15a, 15b, 44b, 45b Vibration detecting piezoelectric element

Claims (2)

(57) [Claims] 1. A vibrator provided on the surface of a vibrating elastic body.
And a motion extractor provided on the surface of the oscillator.
And, wherein in the synthesis of the two vibration modes that are excited by applying a drive signal to the vibrator, the vibrator having a vibration element forms a flat plate shape to form an elliptical motion in the motion extraction member, the vibrating elastic member of an oscillator for driving provided on one side, the motion extraction member to the same position definitive on the other side of the <br/> vibrating elastic member
2. A vibration device, comprising: a vibration detecting vibrator having substantially the same area as that of the motion extractor and for detecting a vibration state of the motion extractor. 2. The method of claim 1, bending the motion extraction member
Only set to the maximum amplitude position of the standing wave of the music vibration, the vibration detecting vibrator, based on the motion extraction member
Vibration apparatus characterized by comprising an integral multiple of the position of a half wavelength of the standing wave.