JP2021197798A - Actuator - Google Patents

Abstract

To provide an actuator that operates with high efficiency.SOLUTION: An ultrasonic motor 1 includes an elastic body 11, a piezoelectric element 15, and a rotor 4. The elastic body 11 has a first surface 21 on which a plurality of first convex portions 23 and a plurality of first concave portions 24 are formed, and a second surface 22 on which a plurality of second convex portions 25 and a plurality of second concave portions 26 are formed. The piezoelectric element 15 includes a piezoelectric body 12 and a plurality of electrodes, and is bonded to the second surface 22 of the elastic body 11 and configured to generate a progressive vibration wave in the elastic body 11 by applying voltages having different phases to the respective electrodes. A contact portion 41 of the rotor 4 is in pressure contact with the first surface 21 of the elastic body 11, and is configured to move relative to the elastic body 11 by the vibration wave.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vibration type actuator.

Vibration type actuators, also called ultrasonic motors, are known. The vibration type actuator includes, for example, a vibrator in which a piezoelectric element and an elastic body are joined, and a moving body that is in pressure contact with the vibrator. As one form of the vibration type actuator, an actuator in which a vibrator and a moving body have an annular shape is known. Such an annular vibration type actuator operates as follows. Vibration is excited to the elastic body by the piezoelectric element. This vibration forms a traveling wave traveling in the circumferential direction in the ring-shaped elastic body. Due to this vibration, the moving body in pressure contact with the vibrator rotates in the circumferential direction in the direction opposite to the traveling direction of the traveling wave. For example, Patent Document 1 also discloses a technique relating to such an annular actuator.

Japanese Unexamined Patent Publication No. 2017-108619

In the vibration type actuator, high efficiency of operation is required. An object of the present invention is to provide an actuator that operates with high efficiency.

According to one aspect of the present invention, the actuator has a first surface in which a plurality of first convex portions and first concave portions are formed, and the first surface in which a plurality of second convex portions and second concave portions are formed. It has an elastic body having a second surface opposite to one surface, a piezoelectric body, and a plurality of electrodes, and is joined to the second surface of the elastic body, and has a phase of each electrode. A piezoelectric element configured to generate a progressive vibration wave in the elastic body by applying a different voltage is in pressure contact with the first surface of the elastic body, and the vibration wave causes the vibration wave. It includes an opposing member configured to move relative to the elastic body.

According to the present invention, it is possible to provide an actuator that operates with high efficiency.

FIG. 1 is a partially cut perspective view showing an outline of a configuration example of an ultrasonic motor according to an embodiment. FIG. 2 is a diagram schematically showing an example of a vertical cross section along the circumferential direction near the contact portion between the stator and the rotor. FIG. 3 is a plan view showing an example of the configuration of the polarization electrode and the drive electrode. FIG. 4 is a diagram showing an outline of a configuration example of a rotor according to a modified example. FIG. 5 is a diagram schematically showing an example of a vertical cross section along the radial direction showing an outline of a configuration example of a stator and a rotor according to a modified example.

[Outline of ultrasonic motor configuration]
An embodiment of the present invention will be described with reference to the drawings. The present embodiment relates to a rotary ultrasonic motor, which is a form of a vibration type actuator. FIG. 1 is a diagram showing an outline of a configuration example of the ultrasonic motor 1 according to the present embodiment. FIG. 1 shows a state in which each part is cut so that the structure of the ultrasonic motor 1 can be seen.

The ultrasonic motor 1 is built on a plate-shaped base 2. The main part of the ultrasonic motor 1 is housed inside a cover 8 provided on the base 2. In FIG. 1, for the sake of explanation, only the back half of the cover 8 is shown. Further, in FIG. 1, for the stator 3, the rotor 4, the bearing 6, the disc spring 7, and the like, which will be described later, only the back side portion is shown with the front side notched. The general shape of each of these members is a substantially disk shape. The space surrounded by the base 2 and the cover 8 has the following configuration.

An annular plate-shaped stator 3 is fixed on the base 2. A shaft 5 is provided in the center of the stator 3 perpendicular to the base 2. The shaft 5 is rotatably supported by a bearing 6 fixed to the cover 8. When a large load is applied in the direction perpendicular to the longitudinal axis of the shaft 5 or when the ultrasonic motor 1 has a high output, it is fixed to the base 2 and rotatably supports the shaft 5 for stabilization. Bearings may be provided. An annular plate-shaped rotor 4 is fixed to the shaft 5. A contact portion 41 is provided on the outer ring portion of the rotor 4. The rotor 4 is pressed in the direction of the stator 3 by, for example, a disc spring 7 as a pressure member, and the contact portion 41 is in pressure contact with the first surface 21 on the upper side of the stator 3.

As will be described in detail later, in the stator 3, for example, the piezoelectric element 15 is fixed to an elastic body 11 made of a metal material. When a high frequency voltage is applied to the piezoelectric element 15, the stator 3 is configured such that the elastic body 11 bends and vibrates due to the expansion and contraction of the piezoelectric element 15, and a traveling wave is generated in the elastic body 11 along the circumferential direction. Has been done. Since the contact portion 41 of the rotor 4 is in pressure contact with the first surface 21 of the elastic body 11, the rotor 4 rotates in the direction opposite to the generated traveling wave. When the rotor 4 rotates, the shaft 5 fixed to the rotor 4 rotates around its axis. In the ultrasonic motor 1, the shaft 5 is used as an output shaft, and the rotation of the shaft 5 is taken out as the rotation of the motor.

[Structure of stator and rotor]
The configurations of the stator 3 and the rotor 4 will be described in more detail with reference to FIG. FIG. 2 is a diagram schematically showing an example of a vertical cross section along the circumferential direction of a part of the contact portion 41 of the stator 3 and the rotor 4. FIG. 2 schematically shows the configuration of each part, and the dimensional ratio and the like are different from the actual ones.

As shown in FIG. 2, the stator 3 has an elastic body 11 and a piezoelectric element 15. The piezoelectric element 15 is bonded to one main surface of the elastic body 11, and the contact portion 41 of the rotor 4 is pressed against the other main surface of the elastic body 11. Of the main surfaces of the elastic body 11, the surface on the side where the contact portion 41 is in pressure contact is referred to as the first surface 21, and the surface on the side to which the piezoelectric element 15 is joined is referred to as the second surface 22. I will decide.

The piezoelectric element 15 has a configuration in which electrodes are provided on both sides of the piezoelectric body 12, for example, lead zirconate titanate (PZT). One of the electrodes is a polarization electrode 13, and the other of the electrodes is a drive electrode 14. The surface of the piezoelectric element 15 on the polarization electrode 13 side and the second surface 22 of the elastic body 11 are bonded, and the piezoelectric element 15 and the elastic body 11 are bonded.

FIG. 3A is a plan view showing an example of the configuration of the polarization electrode 13, and FIG. 3B is a plan view showing an example of the configuration of the drive electrode 14. This example is an example in which nine traveling waves are generated in the circumferential direction of the stator 3, that is, a wave having a period of 40 ° is generated in the circumferential direction, and this wave becomes a traveling wave.

As shown in FIG. 3A, the polarization electrode 13 includes 18 electrodes 13A arranged in the circumferential direction. In the polarization electrode 13, eight electrodes are arranged at intervals of 20 ° in the circumferential direction, eight electrodes are arranged at intervals of 10 °, and eight electrodes are arranged at intervals of 20 °, and the electrodes of 30 ° are sandwiched between them. They are lined up so as to be connected to the eight electrodes of. A gap 28 is provided between the respective electrodes 13A. The piezoelectric body 12 is divided into 18 sections in the circumferential direction corresponding to the positions where the electrodes are provided. As shown by "+" and "-" in FIG. 3A, the piezoelectric body 12 is subjected to a polarization treatment using a polarization electrode 13 at the time of manufacture, so that adjacent divisions are alternately reversed in the thickness direction. It is polarized so that it faces. The portion of the 10 ° electrode and the portion of the 30 ° electrode may be used as a ground electrode or a feedback electrode. FIG. 3 shows an example in which the portion of the 10 ° electrode is used as the feedback electrode and the portion of the 30 ° electrode is used as the ground electrode. The polarization of the portion of the electrode at 10 ° may be in the “+” direction or the “−” direction. Since the portion of the 30 ° electrode is a ground electrode, it does not matter whether or not it is polarized. Here, 9 traveling waves are generated in the circumferential direction, and when the wavelength of the traveling wave is λ, 20 °, 10 °, and 30 ° are 1 / 2λ, 1 / 4λ, and 3 respectively. Corresponds to / 4λ. The wave number, the angle of the electrodes, and the like can be changed as appropriate.

As shown in FIG. 3B, the drive electrode 14 has a ground electrode 14G provided on the opposite side of the 30 ° electrode of the polarization electrode 13 with the piezoelectric body 12 interposed therebetween and a 10 ° electrode of the polarization electrode 13. It has a feedback electrode 14F provided on the opposite side of the electrode, and an A-phase electrode 14A and a B-phase electrode 14B provided between the ground electrode 14G and the feedback electrode 14F, respectively. Although not shown, the ground electrode 14G is electrically connected to the elastic body 11 by a routing electrode or a through hole.

When a high-frequency voltage is applied between the A-phase electrode 14A and the ground electrode 14G (elastic body 11) and between the B-phase electrode 14B and the ground electrode 14G (elastic body 11) during the operation of the ultrasonic motor 1, Since the adjacent sections of the piezoelectric body 12 are polarized in opposite directions to each other, one expands and the other contracts. As a result, a deflection wave is generated in the elastic body 11 bonded to the piezoelectric element 15. Here, since the A-phase electrode 14A and the B-phase electrode 14B are spatially deviated by 1/4 wavelength, the phases of the A-phase electrode 14A and the B-phase electrode 14B are 90, such as sine wave and cos wave. ° By applying different drive signals, the generated waves interfere with each other and a traveling wave is generated in the elastic body 11. The feedback electrode 14F is used to acquire an electromotive force due to the vibration of the stator 3, thereby detecting a change in the characteristics of the stator 3, and the detection result follows the set value of the rotation speed of the ultrasonic motor 1. May be used to make it.

Here, an example in which the piezoelectric body 12 is a continuum is shown, but the present invention is not limited to this. The piezoelectric body 12 may be divided according to the division of the polarization electrode 13.

The explanation will be continued by returning to FIG. The first surface 21 of the elastic body 11 has the same elastic body as the first convex portion 23 extending in the radial direction of the ring-shaped elastic body 11, that is, in the direction perpendicular to the traveling direction of the vibration wave. The first concave portion 24 extending in the radial direction of 11 is repeatedly provided in the circumferential direction. As described above, the first surface 21 of the elastic body 11 has an uneven shape in which the first convex portion 23 and the first concave portion 24 are alternately provided in the circumferential direction. That is, the first surface 21 has a comb tooth shape.

Since the shape of the first surface 21 has the uneven shape as described above, the displacement of the top portion of the first convex portion 23 in contact with the contact portion 41 becomes large. This contributes to improving the operational efficiency of the ultrasonic motor 1.

On the second surface 22 of the elastic body 11, the elastic body is similarly formed with the second convex portion 25 extending in the radial direction of the annular shape elastic body 11, that is, in the direction perpendicular to the traveling direction of the vibration wave. A second concave portion 26 extending in the radial direction of 11 is repeatedly provided in the circumferential direction. As described above, the second surface 22 of the elastic body 11 has an uneven shape in which the second convex portion 25 and the second concave portion 26 are alternately provided in the circumferential direction.

Since the shape of the second surface 22 has the uneven shape as described above, the elastic body 11 tends to vibrate due to the expansion and contraction of the piezoelectric element 15. That is, the efficiency of energy input from the piezoelectric element 15 to the elastic body 11 is improved. This contributes to improving the operational efficiency of the ultrasonic motor 1.

In the present embodiment, the top of the first convex portion 23 and the top of the second convex portion 25 are flat surfaces parallel to each other, and the first concave portion 24 and the second concave portion 26 are of the stator 3. The shape of the cross section in the circumferential direction is a rectangular groove. A groove having a rectangular cross-sectional shape can be easily formed as designed by using, for example, a milling machine. Therefore, in the elastic body 11 of the present embodiment, for example, a flat plate having an annular shape in which the first surface 21 and the second surface 22 are parallel to each other is used, and a groove is provided in the first surface 21. It can be manufactured by forming the recess 24 of 1 and forming the second recess 26 by providing a groove on the second surface 22.

The cross-sectional shape of the groove is not limited to a rectangle, and may be a triangle or a U-shape. It should be noted that it is not considered that the grooves such as the first concave portion 24 and the second concave portion 26 are formed, but that the peaks such as the first convex portion 23 and the second convex portion 25 are formed. , The technical significance is the same. For example, the elastic body 11 may be formed as an integral body, or may be formed by joining those formed by dividing the elastic body 11 into a plurality of pieces.

[Details of the configuration of the first recess and the second recess]
In the present embodiment, the depth, width, and pitch of the first concave portion 24 with respect to the first convex portion 23 are uniform, and the depth, width, and pitch of the first concave portion 24 are uniform with respect to the second convex portion 25 of the second concave portion 26. The depth, width and pitch are uniform. Here, "uniformity" means substantially uniform, and includes not only strictly uniform but also substantially uniform. By making these depths, widths and pitches uniform, the design and manufacture of the ultrasonic motor 1 becomes easy. However, not limited to this, these may be non-uniform. That is, each of the plurality of first recesses 24 may have different depths or widths from each other, or their spacing may differ from place to place. Further, each of the plurality of second recesses 26 may have different depths or widths from each other, or their spacing may differ from place to place. Since the presence of these non-uniform locations can be adjusted to attenuate or disperse the resonance peak of the vibration system, it is possible to reduce the harsh sound in the audible range.

Further, the example shown in FIG. 2 is an example in which the numbers of the first recess 24 and the second recess 26 are the same, but the number is not limited to this. The number of the first recess 24 and the second recess 26 may be different. In particular, as will be described later, it is preferable that the total volume of the first recesses 24 is larger than the total volume of the second recesses 26, so that the number of the second recesses 26 is smaller than the number of the first recesses 24. May be good.

Further, in the present embodiment, the first recess 24 and the second recess 26 have the following relationship.
<Volume of the first recess and the second recess>
The total volume of the first concave portion 24 with respect to the surface of the top of the first convex portion 23, that is, the total volume of the groove portion of the first concave portion 24 is defined as the first volume. The total volume of the second recess 26 with respect to the surface of the top of the second convex portion 25, that is, the total volume of the groove portion of the second recess 26 is defined as the second volume. At this time, the first volume is larger than the second volume. With such a configuration, the elastic body 11 has low elasticity on the first surface 21 side and high elasticity on the second surface 22 side, and the elasticity becomes non-uniform in the elastic body 11.

In the present embodiment, since all of the plurality of first recesses 24 have the same shape, the first volume is the volume of one first recess 24 plus the number of first recesses 24. It will be the multiplied value. However, not limited to this, each of the first recesses 24 may have a different shape and volume. Similarly, in the present embodiment, since all of the plurality of second recesses 26 have the same shape, the second volume is the volume of one second recess 26 and the second recess 26. It is a value multiplied by the number of. However, the present invention is not limited to this, and each of the second recesses 26 may have a different shape and volume. In this embodiment, the volume of one first recess 24 is larger than the volume of one second recess 26.

Consider the deflection vibration of the elastic body 11 when a vibration wave traveling in the circumferential direction is generated in the elastic body 11. In this deflection vibration, focusing on the thickness direction of the elastic body 11 at a certain position, one of the first surface 21 side and the second surface 22 side contracts and the other expands. That is, when the first surface 21 side is contracted, the second surface 22 side is expanded. Further, when the first surface 21 side is extended, the second surface 22 side is contracted. There is a non-stretchable neutral surface between the first surface 21 and the second surface 22.

When the first volume and the second volume described above are equal, the neutral plane is considered to be located between the first plane 21 and the second plane 22. When the first volume is larger than the second volume as in the present embodiment, it is considered that the neutral surface is located on the second surface 22 side of the middle between the first surface 21 and the second surface 22. Be done. On the contrary, when the second volume is larger than the first volume, the neutral surface is considered to be located on the first surface 21 side of the middle between the first surface 21 and the second surface 22.

In FIG. 2, the position of the neutral surface 61 is schematically shown, and the displacement amount on the first surface 21 side and the displacement amount on the second surface 22 side are schematically shown by arrows. As shown in this figure, in the present embodiment, since the neutral surface 61 is biased toward the second surface 22, the displacement on the first surface 21 side is larger than the displacement on the second surface 22 side. ing. Since the contact portion 41 of the rotor 4 is in contact with the first surface 21, for example, the contact portion 41 is in contact with the first surface 21 in the present embodiment as compared with the case where the neutral surface 61 is located between the first surface 21 and the second surface 22. A large displacement of the portion 41 can be obtained.

In the present embodiment, the first concave portion 24 is provided on the first surface 21 so that the displacement of the first surface 21 in contact with the contact portion 41 of the rotor 4 becomes large. Further, a second recess 26 is provided on the second surface 22 so that energy can easily enter the elastic body 11 from the piezoelectric element 15, that is, the elastic body 11 can be easily bent by the expansion and contraction of the piezoelectric element 15. .. On the other hand, the first volume is larger than the second volume so that the displacement of the first surface 21 does not become too small by providing the second recess 26.

<Depth of first recess and second recess>
The depth of the first recess 24 with respect to the top of the first convex portion 23 is defined as the first depth H1, and the depth of the second recess 26 with respect to the top of the second convex portion 25 is defined as the depth H1. The second depth is H2, and the distance between the first surface 21 and the second surface 22 is the height H. At this time, as in the case of the present embodiment shown in FIG. 2,
H1> H2 and H1 + H2 <H
It is preferable that

By doing so, as described above, the first volume is made larger than the second volume. Further, the strength of the elastic body 11 is also ensured by the presence of an elastic member having a sufficient thickness between the bottom of the groove of the first recess 24 and the bottom of the groove of the second recess 26.

<Width of first recess and second recess>
If the volume of the first concave portion 24 or the second concave portion 26 is the same, the first convex portion 23 or the second convex portion 25 is more likely to vibrate when the depth is deeper than when the width is large. Therefore, it is preferable. Therefore, it is preferable to have a large number of narrow grooves rather than a small number of wide grooves.

<Position of first recess and second recess>
As in the present embodiment, the position of the first recess 24 and the position of the second recess 26 are deviated from each other in the traveling direction of the vibration wave, that is, the circumferential direction of the elastic body 11, with the first recess 24. It is preferable that the second recess 26 is less likely to be arranged so as to face the elastic body 11 in the thickness direction. The strength of the elastic body 11 is ensured by such a misaligned arrangement.

However, it is not limited to this. There is a relationship between the number of traveling waves in the circumferential direction and the number of polarization electrodes 13 of the piezoelectric element 15. When the second recess 26 of the elastic body 11 is provided in the gap 28 of the polarization electrode 13, the number of the first recesses 24 is the second recess because of the ease of design and the ease of allocating the processing of the recesses. It is often an integral multiple of 26. Here, the position of the first recess 24 and the position of the second recess 26 may be arranged so that a part or all of them face each other.

Further, as in the present embodiment, it is preferable that the second recess 26 is provided at a position corresponding to the gap 28 between the adjacent electrodes of the polarization electrode 13. As described above, the piezoelectric body 12 is polarized by the polarization electrode 13, and the position corresponding to the gap corresponds to the boundary position between the divisions polarized in opposite directions with each other. The gap 28 is required for insulation between the electrodes 13A. By providing the gap 28, the piezoelectric body 12 is not polarized at the position corresponding to the gap 28. Therefore, even if a voltage is applied to the drive electrode 14, the piezoelectric body 12 does not function to generate a deflection wave at the position corresponding to the gap 28. Therefore, in the present embodiment, the second recess 26 provided for realizing the flexibility of the elastic body 11 is provided at a position corresponding to the gap 28. As a result, the loss of expansion and contraction of the elastic body 11 due to the loss of the elastic body 11 due to the presence of the second recess 26 can be reduced.

If there are a plurality of gaps 28 and at least one of the plurality of second recesses 26 is provided at a position corresponding to any of the gaps 28, the above-mentioned effect can be obtained. Further, when a plurality of second recesses 26 are provided, by providing the second recesses 26 corresponding to all of the plurality of gaps 28, even if the number of the second recesses 26 is increased, the elastic body 11 The loss of expansion and contraction can be minimized.

The number of the second recesses 26 may be larger than the number of the gaps 28. In this case, the second recess 26 is provided at a position other than the position corresponding to the gap 28. The number of second recesses 26 may be less than the number of gaps 28. In this case, the second recess 26 may not be provided correspondingly to all the gaps 28.

[others]
A thermosetting adhesive may be used for joining the elastic body 11 and the piezoelectric element 15. When a thermosetting adhesive is used, in the manufacture of the stator 3, the elastic body 11 and the piezoelectric element 15 are superposed via the thermosetting adhesive, and then they are heated. The coefficient of thermal expansion of the elastic body 11 and the coefficient of thermal expansion of the piezoelectric element 15 are different. Since the deformation due to heating is larger in the elastic body 11 than in the piezoelectric element 15, distortion occurs when the stator 3 is cooled after the adhesive is cured by heating. In the present embodiment, since the deformation of the elastic body 11 is absorbed to some extent by providing the second recess 26 on the second surface 22 which is the joint surface of the elastic body 11, it depends on the difference in the coefficient of thermal expansion. Distortion is reduced. As a result, the piezoelectric body 12 is prevented from cracking, the processing time for removing the strain after bonding is shortened, and the manufacturing efficiency is improved. Further, according to the present embodiment, the rate of occurrence of microcracks, which is sometimes difficult to find in the manufacturing process of the piezoelectric body 12, is significantly reduced, so that the reliability and life of the ultrasonic motor 1 are improved. The same applies even if brazing or the like is used for joining the elastic body 11 and the piezoelectric element 15.

In the above-described embodiment, as shown in FIG. 4A, the rotor 4 has a shape in which the contact portion 41 is provided on the outer ring portion of the disk-shaped support 42 having the hole 43 in the central portion. ing. However, it is not limited to this. For example, the rotor 4 may have a propeller-like shape in which a part of the contact portion 41 of the disk-shaped support 42 and the outer ring portion is cut out. For example, as shown in FIG. 4B, the rotor 4a may have a shape in which the disc-shaped support 42 and the contact portion 41 of the outer ring portion are notched on all sides. That is, the rotor 4a may have a shape having a cross-shaped support 42a having a hole 43a in the center and a contact portion 41a provided at the end thereof. Further, for example, as shown in FIG. 4C, the rotor 4b has a shape having a rod-shaped support 42b having a hole 43b in the center portion and a contact portion 41a provided at the end portion thereof. May be good. Further, for example, as shown in FIG. 4D, even if the rotor 4c has a shape having a rod-shaped support 42c extending from the hole 43c to one side and a contact portion 41c provided at the end thereof. good. In addition, the rotor 4 can take various shapes.

Further, the shape of the contact portion 41 can be changed in various ways. An example is shown in FIG. FIG. 5 is a diagram showing a vertical cross section along the diameter of the stator 3d and the rotor 4d. As shown in FIG. 5, the rotor 4d is configured so as to straddle the elastic body 11d provided with the piezoelectric element 15d of the stator 3d at the outer ring portion thereof. That is, the rotor 4d has a contact portion 41d in contact with the first surface 21d of the elastic body 11d in the outer ring portion of the disk-shaped support 42d having a hole 43d in the central portion. Further, on the outer peripheral side and the inner peripheral side of the contact portion 41d, a hanging portion 44d provided along the side surface of the elastic body 11d is provided. Further, also in such an example, the support 42d, the contact portion 41d, and the hanging portion 44d of the rotor 4d may be changed to a propeller-like shape as described with reference to FIG.

In the above-described embodiment, the stator 3 having the elastic body 11 and the piezoelectric element 15 is fixed to the base 2 and the cover 8, and the rotor 4 rotates with respect to the base 2 and the cover 8. I explained, but it is not limited to this. The oscillator having the elastic body 11 and the piezoelectric element 15 may rotate with respect to the base 2 and the cover 8 instead of being provided as a stator. That is, the above-mentioned stator 3 and rotor 4 may be configured to move relative to each other. In other words, the rotor 4 is a contact member that is in pressure contact with the elastic body 11 of the vibrator having the elastic body 11 and the piezoelectric element 15, and may function as a facing member facing the elastic body 11.

Further, in the above-described embodiment, the example in which the ultrasonic motor 1 has an annular shape has been described, but the shape of the actuator is not limited to this. For example, the actuator may have other shapes such as an elliptical shape and a linear shape.

Although the present invention has been described above with reference to preferred embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. Nor.

1 Ultrasonic motor 2 Base 3 Stator 4 Rotor 5 Shaft 6 Bearing 7 Countersunk spring 8 Cover 11 Elastic body 12 Piezoelectric body 13 Polarization electrode 14 Drive electrode 15 Piezoelectric element 21 First surface 22 Second surface 23 First convex Part 24 First concave part 25 Second convex part 26 Second concave part 28 Gap 41 Contact part 61 Neutral surface

Claims (11)

A first surface on which a plurality of first convex portions and first concave portions are formed, and a second surface opposite to the first surface on which a plurality of second convex portions and second concave portions are formed. With an elastic body,
It has a piezoelectric body and a plurality of electrodes, and is bonded to the second surface of the elastic body. By applying a voltage having a different phase to each electrode, a progressive vibration wave is applied to the elastic body. Piezoelectric elements configured to generate and
An actuator comprising an opposing member that is in pressure contact with the first surface of the elastic body and is configured to move relative to the elastic body by the vibration wave. In the elastic body, the first volume, which is the total volume of the first concave portion with respect to the first convex portion, is the volume of the second concave portion with respect to the second convex portion. The actuator according to claim 1, which is larger than the total second volume. The depth, width and pitch of the first concave portion with respect to the first convex portion are substantially uniform.
The depth, width and pitch of the second concave portion with respect to the second convex portion are substantially uniform.
The actuator according to claim 1 or 2. The depth of the first recess is defined as the first depth H1.
The depth of the second recess is defined as the second depth H2.
When the distance between the first surface and the second surface is H,
H1> H2 and H1 + H2 <H
The actuator according to claim 3. The actuator according to any one of claims 1 to 4, wherein the traveling direction of the vibration wave is different from the position of each of the first recesses and the position of each of the second recesses. The actuator according to any one of claims 1 to 4, wherein the position of at least one of the second recesses coincides with the position of the first recess in the traveling direction of the vibration wave. According to any one of claims 1 to 6, the second recess is provided at a position corresponding to at least one of the boundaries between the sections in which the directions of polarization of the piezoelectric body are different from each other. The actuator described. The actuator according to any one of claims 1 to 6, wherein the second recess is provided at least at a position corresponding to a boundary between divisions in which the directions of polarization of the piezoelectric body are different from each other. The actuator according to any one of claims 1 to 8, wherein a thermosetting adhesive is used for joining the elastic body and the piezoelectric element. The actuator according to any one of claims 1 to 8, wherein brazing is used for joining the elastic body and the piezoelectric element. The first concave portion is a groove having a rectangular cross-sectional shape provided in a direction perpendicular to the traveling direction of the vibration wave on a surface connecting the tops of the first convex portion.
The second concave portion is a groove having a rectangular cross-sectional shape provided in a direction perpendicular to the traveling direction of the vibration wave on the surface connecting the tops of the second convex portion.
The actuator according to any one of claims 1 to 10.

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