JPH05115846A - Ultrasonic vibrator and driver having the same - Google Patents

Abstract

PURPOSE:To provide an ultrasonic vibrator which is easy to design and manufacture, and is compact, and a driver having the same. CONSTITUTION:A flex vibrating laminate 29 for carrying out flex vibration and a longitudinal vibration laminate 25 for carrying out longitudinal vibration are formed in a cylindrical shape each and an ultrasonic vibrator transducer 20 is constituted by joining them. In the ultrasonic vibrator transducer 20, by composing flex vibration and longitudinal vibration, ultrasonic elliptical motion is generated in projections 35a-35e. A driver for driving moving members by the projections 35a-35e is also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vibrator using an electromechanical conversion element such as a piezoelectric element as a vibration source, and a driving device having the vibrator.

[0002]

2. Description of the Related Art Recently, ultrasonic motors have been in the spotlight as new motors replacing electromagnetic motors. This ultrasonic motor is not only new in principle, but has the following advantages over conventional motors. (1) Thin, lightweight and compact. (2) Low speed and high torque can be obtained without gears. (3) The parts configuration is simple and highly reliable. (4) There is no exchange of magnetic effects. (5) There is no backlash and positioning is easy. Thus, in order to make use of these advantages, various applied technologies are being researched.

Ultrasonic motors are roughly classified into rotary type and linear type. 10 to 13 are views showing a conventional example of a linear type ultrasonic motor.

FIG. 10 is a diagram showing a first conventional example. When the Langevin type piezoelectric vibrator 1 on the left side of the figure is vibrated and the tip of the horn 2 is applied to the propagation rod 3 made of an elastic body, a bending traveling wave is generated in the propagation rod 3. This bending traveling wave propagates rightward in the propagation rod 3 as indicated by a solid arrow D. Then, this traveling wave excites the Langevin type piezoelectric vibrator 5 through a similar horn 4 attached to the right end of the propagating rod 3. At this time, L and R in the figure are appropriately selected and impedance matching is performed to absorb all the energy of the traveling wave. By doing so, the traveling wave always proceeds from the left to the right constantly.

When the slider 6 is held in pressure contact with the surface of the propagating rod 3 in which such a bending traveling wave is generated with a certain pressing force, the slider 6 moves leftward in the figure as indicated by a solid arrow H. Move on.

FIG. 11 is a perspective view schematically showing the relationship between the bending traveling wave of the propagation rod 3 and the slider 6. In the figure, 3A is an elastic body corresponding to the propagation rod 3, and 6A is a slider 6.
Is a moving body equivalent to. Elastic body 3 as shown in FIG.
The mass point P of A draws an elliptical locus. Therefore, the moving body 6 is placed on the elastic body 3A which draws a counterclockwise elliptical orbit in this figure.
When A is brought into pressure contact with a predetermined pressure, the moving body 6A is driven in the direction opposite to the traveling direction D of the traveling wave, that is, in the left direction in the drawing. If the traveling direction of the traveling wave is reversed, the moving body 6A is driven rightward in the figure.

FIG. 12 is a diagram showing the structure of another conventional example. A vibrating piece 8 is attached to the tip of the Langevin type vibrator 7. The tip of the vibrating body 8 is in contact with the slider 6B with a constant pressing force in a state of being inclined at a predetermined angle θ with respect to the normal line of the surface of the slider 6B. AC power supply 9 for this Langevin type vibrator 7
Therefore, when an AC voltage having the same frequency as the natural frequency of the Langevin-type vibrator is applied, the Langevin-type vibrator 7 performs longitudinal vibration. At this time, since the tip of the vibrating piece 8 is in contact with the slider 6B at a predetermined angle θ, lateral vibration is also performed.
By combining these vibrations, the tip of the vibrating piece 8 draws an elliptical locus. Thus, the slider 6B moves to the left as indicated by the arrow in the figure.

FIG. 13 is a view showing still another conventional example, showing the structure of the vibrator disclosed in Japanese Patent Laid-Open No. 62-134278. Piezoelectric elements 11 and 12 are bonded to both surfaces of a rectangular-shaped conductive vibrator 10. Lead terminals A and B for voltage application are drawn from the piezoelectric elements 11 and 12, and a ground terminal E is drawn from the vibrator 10. The shape of the vibrator 10 is
The shape is such that the resonance frequency of the longitudinal vibration and the resonance frequency of the flexural vibration are the same. Thus, when an AC voltage having the resonance frequency is applied to the lead terminals A and B with a constant phase difference, the mass point of the end surface S of the vibrator 10 makes an elliptic motion. Then, when the slider 6C is pressed against the end surface S with a constant pressure, the slider 6C moves in the direction of the arrow HH in the figure. This moving direction is determined by the phase difference between the voltages applied to the terminals A and B.

[0009]

The basic principle of the ultrasonic motor shown in FIGS. 10 to 13 is to transfer the energy of the elliptical locus motion at the mass point of the vibrator to the moving body (slider) by friction.

In the first conventional example shown in FIG. 10, since traveling waves have to be generated in the entire propagating rod 3, there is a problem that the efficiency is poor and the entire apparatus becomes large.

Further, in the second conventional example shown in FIG.
The traveling direction of the slider 6B is limited to one direction, and
As in the conventional example, there is a problem that the entire apparatus becomes large.

Further, in the third conventional example shown in FIG. 13, since the vibration output is obtained by the piezoelectric elements 11 and 12 bonded to both sides of the vibrator 10, a large force for moving the slider 6C is secured. Difficult to do. If the number of piezoelectric elements 11 and 12 bonded to the side surface of the vibrator 10 is increased in order to obtain a larger vibration output, there is a drawback that the device becomes larger by that amount. Further, in this conventional example, the longitudinal vibration and the flexural vibration of the vibrator 10 are combined to generate elliptical vibration, but a large output cannot be obtained unless both vibrations are in a resonance state. Therefore, it is necessary to match the resonance frequency of longitudinal vibration with the resonance frequency of flexural vibration. For this reason, the shape of the vibrator 10 must be determined by trial and error, which requires a large amount of labor and is not easy to manufacture.

An object of the present invention is to provide an ultrasonic vibrator which is compact, has a high energy conversion efficiency, can output a large vibration output, and is easy to manufacture, and a driving device having the vibrator.

[0014]

In order to solve the above problems, the ultrasonic vibrator of the present invention is a cylindrical ultrasonic vibrator, and the ultrasonic vibrator performs bending vibration. It has a bending vibration member and a vertical vibration member that performs longitudinal vibration, and is characterized in that ultrasonic elliptical vibration is obtained by combining the bending vibration and the longitudinal vibration.

Further, in order to solve the above-mentioned problems, a driving device of the present invention has the ultrasonic vibrator and a movable member that comes into contact with the ultrasonic vibrator, and the movable member is arranged in an arbitrary plane direction. It is characterized by being moved to.

Further, in order to solve the above-mentioned problems, the driving device of the present invention comprises a moving element including the ultrasonic transducer, and guide means arranged so as to contact the moving element and guiding the moving element. And the ultrasonic elliptical vibration of the ultrasonic oscillator enables the moving element to reciprocate linearly along the guide means.

[0017]

[Function] By joining a columnar or ring-shaped bending vibration member to a columnar vertical vibration member, an ultrasonic transducer having a cylindrical shape as a whole is formed. An ultrasonic elliptical vibration is obtained by applying bending vibration and longitudinal vibration to the member. Further, the movable member is brought into contact with the ultrasonic oscillator to drive the movable member, or the mover having the ultrasonic oscillator is driven.

[0018]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) FIG. 1A is a perspective view showing the structure of a first embodiment of an ultrasonic transducer 20, and FIG. 1B is a plan view thereof. Reference numeral 21 is a cylindrical lower elastic body, and the lower elastic body 21 is made of a metal material such as stainless steel, aluminum, and duralumin. On the upper surface of the lower elastic body 21, a thin disk-shaped PZT is formed.
A few piezoelectric elements 23 such as
Dozens of sheets are laminated and adhered. In FIG. 3A, two piezoelectric elements 23 are typically taken out. Each of the piezoelectric elements 23 is uniformly polarized so as to be perpendicular to the surface, and both surfaces thereof are subjected to electrode treatment such as baking silver. Then, the layers are stacked so that the polarization directions are opposite to each other. Hereinafter, the laminated body thus laminated is referred to as a longitudinal vibration laminated body 25. In each piezoelectric element 23, the electrodes are connected by skipping one sheet, and one constitutes a ground terminal (G terminal) and the other constitutes a voltage input terminal (C terminal).

On the upper surface of the longitudinal vibration laminate 25, a disc-shaped lower insulator 27 made of an insulating ceramic material such as alumina is adhered and fixed. Piezoelectric elements 29-1 and 29-2 are laminated on the upper surface of the lower insulator 27. For clarity, these two are taken out.
These piezoelectric elements 29-1 and 29-2 are polarized so that they are oriented in a direction perpendicular to the plane and are reversed in half of the plane. Further, both sides of each piezoelectric element are subjected to electrode treatment such as baking silver on the entire surface. Hereinafter, these two layers are referred to as a flexural vibration laminate 29. Piezoelectric element 29
-1, 29-2 are laminated such that the boundary lines of the respective polarizations indicated by the dotted lines are orthogonal to each other. In this case, the polarization boundary direction of the piezoelectric element 29-2 is the x-axis direction, the polarization boundary direction of the piezoelectric element 29-1 is the y-axis direction, and the direction perpendicular to these axes is the z-axis direction. Electrical terminals A, G, and B are taken out from the upper surface, the adhesive surface, and the lower surface of the flexural vibration laminate 29 (however, the G terminal is
It is a ground terminal).

On the upper surface of the flexural vibration laminate 29, a disc-shaped upper insulator 31 made of an insulating ceramic material such as alumina is adhered and fixed. A columnar upper elastic body 33 made of a metal material such as stainless steel, aluminum or duralumin is adhered and fixed to the upper surface of the upper insulator 31. 1 (a), (b)
As can be seen, hemispherical projections 35a to 35e are formed on the upper central portion of the upper elastic body 33, two on the side surface in the x-axis direction and two in the y-axis direction. In the above description, the bonding of each member is made with an adhesive such as epoxy. Alternatively, as shown in FIG. 4, a through hole is provided in the central portion of the ultrasonic transducer 20 and the upper elastic body 3 is formed.
3 is formed with a screw hole 45. Then, the screws 46 may be fitted from the bottom surface of the lower elastic body 21 to crimp and fix the respective members.

Next, the operation of this embodiment will be described with reference to FIGS. In FIG. 2, the longitudinal vibration laminated body 25 and the bending vibration laminated body 2 of the ultrasonic transducer 20 of FIG.
9 and the like are omitted, and only the protrusion 35a is illustrated.

As an example, a case where the lower surface of the lower elastic body 21 is fixed to a base (not shown) will be described. An alternating voltage having a frequency corresponding to the primary bending resonance vibration is applied to the terminal A of FIG. 1 by a power source (not shown). Then, the ultrasonic transducer 20 makes bending vibration as shown in FIG. 2A in the xz plane. Therefore, the protrusion 3 formed on the upper surface
5a vibrates in the x-axis direction as shown in FIG. On the other hand, when an alternating voltage of the same frequency is applied to the terminal C by a power source (not shown), the ultrasonic transducer 20 makes a non-resonant longitudinal vibration as shown in FIG. The phase of these vibrations is +
When it is moved by 90 ° or −90 °, the protrusion 3
5a, 35b, and 35c perform ultrasonic elliptic motion clockwise or counterclockwise in the xz plane. Thus, with respect to these protrusions 35a, 35b, 35c,
When sliders (not shown) are slidably brought into contact with each other, the sliders can be slid by the ultrasonic elliptical motion of the protrusions.

Next, an alternating voltage having a frequency corresponding to the primary bending resonance vibration is applied to the terminal B of FIG. 1 by a power source (not shown). Then, the ultrasonic transducer 20 performs bending vibration as shown in FIG. 2A on the yz plane. Therefore, the protrusion 35a formed on the upper surface vibrates in the y-axis direction as shown in FIG. On the other hand, when an alternating voltage of the same frequency is applied to the terminal C by a power source (not shown), the ultrasonic transducer 20 makes a non-resonant longitudinal vibration as shown in FIG. The phase of these vibrations is + 90 ° or -90 °
When they are staggered, the protrusions 35a, 35d, and 35e perform a clockwise or counterclockwise ultrasonic elliptical motion in the yz plane. Thus, these protrusions 35
When a slider (not shown) is slidably brought into contact with a, 35d, and 35e, the slider can be slid by the ultrasonic elliptical motion of the protrusion.

Next, the two-dimensional driving will be described. Alternating voltages having the same bending resonance frequency in phase or 180 ° out of phase are simultaneously applied to the terminals A and B. In this case, by appropriately adjusting the magnitude of the vibration amplitude, it becomes possible to cause the protrusion 35a to perform a linear reciprocating motion of any magnitude in any direction within the xy plane. On the other hand, at the same time, an alternating voltage of the same frequency is applied to the terminal C to cause longitudinal vibration to a constant phase difference (+90
Or −90 °). Then, ultrasonic elliptical vibration can be generated in the projection 35a in an arbitrary plane including the z axis. At this time, if a flat plate-shaped slider is slidably brought into contact with the protrusion 35a, the slider can move in any direction within the xy plane.

An example of an xy stage using this principle is shown in FIG. (A) is the side view, (b) is a top view. The ultrasonic transducer 20 described above is fixed to the central portion of the upper surface of the base 40 made of stainless steel or the like using an adhesive or the like. Further, on the upper surface of the base 40, four springs 42a to 42d are provided upright at four positions equidistant from the central portion. The base 4 is attached to these springs 42a to 42d.
The stage 41 is fixed so as to face 0 and contact the protrusion 35 a of the ultrasonic transducer 20. The stage 41 is made of stainless steel, aluminum, aluminum whose surface is subjected to an oxidation treatment, or the like.
As shown in (b), it is supported by the springs 42a to 42d by four corners. Due to the biasing force of these springs, the stage 41 is in contact with the projection 35a with a certain pressing force.

In the thus constructed device, when an ultrasonic elliptical vibration is generated in the vibrator 20 by a power source (not shown), the projection 35a makes an ultrasonic elliptical motion, whereby the stage 41 moves. It is possible to move in any direction in the xy plane.

Based on the same concept, the flexural vibration laminate 2
By combining the flexural resonance vibration caused by No. 9 and the non-resonance longitudinal vibration caused by the longitudinal vibration laminate 25, the other protrusions 35b to 3b
The same ultrasonic elliptical motion can be generated in any of 5e, and the slider can be two-dimensionally driven as described above by using any protrusion. In this way, since the laminated piezoelectric element is used as the main vibration source, essentially large mechanical output can be obtained, and the frequency of the driving power supply does not have to match the natural frequency of the elastic body as in the conventional case. However, a large mechanical output can be obtained. Therefore, it does not need to be driven without resonance, there are few restrictions on design, and it is easy to manufacture.

(Second Embodiment) FIGS. 5 and 6 are views for explaining the second embodiment. In the following embodiments, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted or simplified. In this embodiment, the ultrasonic transducer 20 described in the first embodiment is used.
Are connected in series using two (ultrasonic transducers 20a, 20b). However, the arrangement relationship between the longitudinal vibration laminated body and the flexural vibration laminated body in each of the ultrasonic transducers 20a and 20b is configured differently from that of the first embodiment. The ultrasonic transducers 20a and 20b are bonded to each other with an adhesive such as epoxy sandwiching the central elastic body 22. Also,
In FIG. 5, terminals drawn out from the vertical vibration laminates 25a and 25b are omitted.

By using such an ultrasonic oscillator, a self-propelled linear motor as shown in FIG. 6 can be constructed. A rail 50 is arranged above the ultrasonic vibrator so that the projections 35c and 36c formed at both ends can come into contact with each other. The central elastic body 22 is provided with a support member 51 formed of stainless steel or the like and extending upward. A base 54 is mounted on the rail 50 and a bearing 5
5, the base 54 is movable with respect to the rail. The support member 51 penetrates through the central portion of the base 54, and the support member 51 is fastened by a screw 52 via a spring 53. Thus, the ultrasonic transducer has a certain pressing force and the projection 35
It is in contact with the lower surface of the rail 50 via c and 36c. Note that, in this figure, other protrusions, terminals, and the like are omitted.

Similar to the above-mentioned embodiment, an alternating voltage is applied to each of the ultrasonic transducers 20a and 20b so as to perform resonant bending vibration and non-resonant longitudinal vibration. By synthesizing and controlling these vibrations, the protrusions 35c, 36c at both ends are
Generate ultrasonic elliptical motion in the same direction. As a result,
Since the base 54 moves with respect to the rail 50, a self-propelled and very compact linear motor can be constructed.

(Third Embodiment) FIG. 7 is a diagram for explaining the third embodiment. The ultrasonic transducer of the present embodiment has basically the same configuration as that of the second embodiment. Figure (b)
As shown in, the first-order symmetric bending vibration at the free end-free end of the rod has its vibration mode at two points. This is a position approximately 0.244 times the total length from the end. The ultrasonic transducer is supported by the support members 51 at both positions. In order to resonate the first-order symmetrical bending vibration, as shown in FIG. (A), the bending vibration laminated body 29 described in the first embodiment includes elastic bodies 21a and 21b of the ultrasonic transducers 20a and 20b. It is glued and fixed in between.
The flexural vibration laminate 29 is composed of two piezoelectric elements as in the first embodiment, and the polarization direction of each piezoelectric element is as shown in the figure. Even if this ultrasonic transducer is used, the same effect as that of the second embodiment can be obtained.

(Fourth Embodiment) FIG. 8 is a diagram for explaining the fourth embodiment. As shown in Figure (c), the first-order antisymmetric bending vibration between the free end and the free end of the rod has three vibration modes.
It has a section in some places. The ultrasonic transducer of the present embodiment is supported by the support member 51 at the position of the central node therein. In order to generate the first-order antisymmetric bending vibration,
The flexural vibration laminates 29a, 2 are placed at the positions where the strain is maximum.
9b is arranged and connected as shown in FIG. Also,
The polarization directions of the piezoelectric elements forming the bending vibration laminated bodies 29a and 29b are as shown in the figure.
Then, by adjusting the voltage phase applied to the longitudinal vibration laminated bodies 25a and 25b and the bending vibration laminated bodies 29a and 29b, ultrasonic elliptical motion is given to the protrusions 35c and 36c formed at both ends. Even if such an ultrasonic transducer is used, the same effect as that of the second embodiment can be obtained. Of course, as shown in FIG. 7A, the longitudinal vibration laminate 25 may be arranged in the support member 51.

(Fifth Embodiment) FIG. 9 is a view for explaining the fifth embodiment. FIG. 7A is a perspective view, FIG. 9B is a perspective view of a portion that performs flexural vibration, and FIG. 7C is a plan view of the portion that performs flexural vibration.
The difference between this embodiment and the first embodiment is that, as is clear from FIG. 6B, the portion that performs bending vibration is formed in a cylindrical shape (this portion is referred to as the bending piezoelectric body 59).
And). Therefore, this part will be described in detail and the other parts will be omitted.

The bending piezoelectric body 59 is a piezoelectric element such as PZT, is formed in a cylindrical shape, and is polarized in four directions in the direction of the arrow as shown. An electrode 61 is attached to the entire inner surface of the bending piezoelectric body 59 by a baked silver electrode. On the outer peripheral surface of the bending piezoelectric body 59, four electrodes 60a to 60d corresponding to the four-divided polarization are attached by a baked silver electrode. The electrodes 60a, 60c and 60b, 60d polarized in the same direction are connected to form an A terminal and a B terminal, respectively. Further, the electrode on the inner peripheral surface is grounded (see FIG. (C)).
The bending piezoelectric body 59 is adhered in series to the longitudinal vibration laminate 25 described in the first embodiment. Further, on the upper surface of the bending piezoelectric body 59, a disc-shaped elastic body 33 formed of a metal material such as stainless steel and having a protrusion 35 at the center thereof.
Are glued together.

An alternating voltage having a frequency corresponding to the resonance vibration of the bending vibrations orthogonal to each other is applied to the A terminal and the B terminal of the ultrasonic vibrator thus constructed. Further, an alternating voltage having a frequency corresponding to the same frequency as that is applied to the longitudinal vibration laminate 25. By appropriately adjusting these phases, an ultrasonic elliptical motion can be generated in the protrusion 35. Of course, the driving device as in the above-described embodiments can be constructed by using this ultrasonic transducer.

In the above-mentioned embodiment, the bending vibration of the cylindrical rod is used for resonance, and the longitudinal vibration is excited by non-resonance. However, if the shape and size are properly set, it is possible to drive the longitudinal vibration by resonance. Furthermore, it is also possible to drive both bending vibration and longitudinal vibration without resonance. Further, the number of stacked layers is not limited to that described in the embodiment, and should be appropriately selected according to the output of the vibrator and the output of the motor.

Although the present invention has been described with reference to various embodiments, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the gist of the present invention. Of course.

[0039]

According to the present invention, since a member that performs flexural vibration and a member that performs longitudinal vibration are integrated in a cylindrical shape, it is possible to provide an ultrasonic vibrator that is easy to manufacture, compact, and has high energy conversion efficiency. be able to. Further, by using this ultrasonic oscillator, it is possible to provide a driving device such as a compact linear motor or a two-dimensional moving stage.

[Brief description of drawings]

1A is a diagram showing a first embodiment of an ultrasonic transducer according to the present invention, and FIG. 1B is a plan view thereof.

2A is a side view showing a state in which the ultrasonic transducer of FIG. 1 is flexibly vibrating, and FIG. 2C is a plan view thereof. Further, (b) is a side view showing a state where the ultrasonic transducer of FIG. 1 is longitudinally vibrating, and (d) is a plan view thereof.

3A is a side view of a drive device that drives the xy stage using the ultrasonic transducer of FIG. 1, and FIG. 3B is a plan view thereof.

FIG. 4 is a side view showing a modified example of the ultrasonic transducer of FIG.

FIG. 5 is a side view showing a second embodiment of the ultrasonic transducer according to the present invention.

6 is a side view showing a state in which a self-propelled linear actuator is configured by using the ultrasonic transducer of FIG.

FIG. 7 (a) is a diagram showing a third embodiment of an ultrasonic transducer according to the present invention, and FIG. 7 (b) is a diagram showing a vibration mode of its first-order symmetrical bending vibration.

8A is a diagram showing a fourth embodiment of an ultrasonic transducer according to the present invention, FIG. 8B is a diagram showing a modified example thereof, and FIG. 8C is a first antisymmetric bending thereof. It is a figure which shows the vibration mode of vibration.

FIG. 9A is a diagram showing a fifth embodiment of an ultrasonic transducer according to the present invention, and FIG. 9B is an enlarged perspective view of a portion of the ultrasonic transducer that causes bending vibration; (C) is a plan view of FIG.

FIG. 10 is a diagram showing a configuration of a conventional ultrasonic linear motor.

FIG. 11 is a diagram showing a traveling wave generated in the elastic body of the conventional example.

FIG. 12 is a diagram showing the configuration of another conventional example.

FIG. 13 is a diagram showing the configuration of still another conventional example.

[Explanation of symbols]

20 ... Ultrasonic vibrator, 25 ... Longitudinal vibration laminated body, 29 ... Flexural vibration laminated body, 35a-35e ... Projection body, 41 ... Stage (movable member).

Claims (3)

[Claims] 1. An ultrasonic vibrator formed in a cylindrical shape, the ultrasonic vibrator having a bending vibration member that performs bending vibration and a vertical vibration member that performs longitudinal vibration. An ultrasonic transducer, wherein ultrasonic elliptical vibration is obtained by combining vibration and longitudinal vibration. 2. The ultrasonic vibrator according to claim 1, and a movable member that comes into contact with the ultrasonic vibrator, and the movable member is moved in an arbitrary plane direction. Drive device. 3. The ultrasonic vibration, comprising: a mover including the ultrasonic vibrator according to claim 1; and guide means arranged to contact the mover and guiding the mover. A drive device that enables linear reciprocating movement of the moving element along guide means by ultrasonic elliptical vibration of the child.