JP2015208077A - piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator capable of easily and reliably displacing a body to be driven when displacing the body to be driven by external force other than the piezoelectric actuator.SOLUTION: A piezoelectric actuator includes: a piezoelectric element provided with a plurality of electrodes; a diaphragm at least longitudinally vibrating by applying a signal to the piezoelectric element; and a body to be driven brought into contact with the diaphragm. The signal is applied to at least a first electrode and a second electrode out of the plurality of electrodes when causing the diaphragm to longitudinally vibrate. A third electrode is disposed between the first electrode and the second electrode in a direction different from a vibration direction of longitudinal vibration.

Description

  The present invention relates to a piezoelectric actuator.

  The piezoelectric actuator is a driving device having a piezoelectric element that converts a driving voltage such as a high-frequency AC voltage into mechanical vibration and a driven body that is driven by the piezoelectric element. As a form of this piezoelectric actuator, a piezoelectric actuator having a rotor or a longitudinal member as a driven body is known (for example, Patent Document 1). The piezoelectric actuator transmits bending vibration of a piezoelectric element via a convex portion protruding from a vibrating body including the piezoelectric element, and rotates the rotor in a predetermined direction.

  In the piezoelectric actuator described in Patent Document 1, the convex portion of the vibrating body vibrates so as to draw an elliptical orbit. Then, the vibration pattern of the vibrating body is changed by selecting the energization pattern to each electrode of the vibrating body, and the direction of vibration of the convex part of the vibrating body is changed, whereby the rotor is rotated in the opposite direction (counterclockwise). And a clockwise direction). Moreover, in the piezoelectric actuator described in Patent Document 1, the vibrating body is urged toward the rotor by a coil spring.

  Such a piezoelectric actuator is attracting attention as a drive source for each part of each robot such as a joint of the robot. When teaching the robot, the piezoelectric actuator is stopped and external force is applied to bend or extend the joint of the robot.

JP 2007-189900 A

  However, in the piezoelectric actuator described in Patent Document 1, when teaching the robot, the piezoelectric actuator is stopped and the convex portion of the vibrating body is always in contact with the rotor, so that the rotor is braked. Therefore, it is necessary to apply a force that exceeds the holding force of the brake. When the drive source of the robot has a reduction gear, a larger force is required for the reduction ratio. In addition, for example, when a robot is instructed to perform a delicate operation such as a hand feeling with specialized skills, there is a problem that if the holding force is large, the hand feeling is difficult to be transmitted accurately.

  An object of the present invention is to provide a piezoelectric actuator capable of easily and reliably displacing a driven body when the driven body is displaced by an external force other than the piezoelectric actuator.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

(Application example 1)
A piezoelectric actuator according to the present invention includes a piezoelectric element provided with a plurality of electrodes,
A diaphragm that vibrates at least longitudinally by applying a signal to the piezoelectric element;
A driven body that comes into contact with the diaphragm,
When causing the diaphragm to vibrate longitudinally, the signal is applied to at least the first electrode and the second electrode of the plurality of electrodes,
A third electrode is disposed between the first electrode and the second electrode in a direction different from the vibration direction of the longitudinal vibration.

  As a result, when the diaphragm vibrates longitudinally, the friction force between the diaphragm and the driven body can be reduced without displacing the driven body and compared to the non-driven state. . Thus, when the driven body is displaced by an external force other than the piezoelectric actuator, the driven body can be easily and reliably displaced. Thus, for example, when the piezoelectric actuator of the present invention is applied to a robot and used as a drive source for a joint of the robot, when the robot is taught, the diaphragm is vibrated longitudinally and easily and externally. The joint of the robot can be surely bent or extended, whereby the teaching can be performed easily and reliably.

  Also, when the vibration plate is vibrated longitudinally by applying a signal only to the electrode in the vibration direction of the longitudinal vibration of the contact portion of the vibration plate with the driven body, i.e., the vertical electrode passing through the center of the vibration body. In comparison, the balance of the force applied from the diaphragm to the driven body in the direction orthogonal to the vibration direction of the longitudinal vibration is stabilized, and thus the vibration can be stabilized.

  In addition, the impedance of the piezoelectric element at the time of resonance of the diaphragm can be increased compared with the case where the signal is applied to all the electrodes and the diaphragm is longitudinally vibrated, thereby stabilizing the vibration, In addition, power consumption can be reduced.

(Application example 2)
In the piezoelectric actuator according to the present invention, it is preferable that the first electrode and the second electrode are provided asymmetrically with respect to a predetermined first straight line extending in a direction different from the vibration direction of the longitudinal vibration.
Thereby, a vibration can be stabilized more.

(Application example 3)
In the piezoelectric actuator according to the present invention, it is preferable that the plurality of electrodes are provided in line symmetry with respect to a predetermined first straight line extending in a direction different from the vibration direction of the longitudinal vibration.

  Thereby, when it is set as the structure which displaces a to-be-driven body to the normal / reverse direction, it can reduce that the nonuniformity arises in the drive characteristic of a to-be-driven body by the displacement direction of a to-be-driven body.

(Application example 4)
In the piezoelectric actuator according to the present invention, the diaphragm has a convex portion that comes into contact with the driven body,
It is preferable that the first electrode and the second electrode are arranged closer to the convex portion than the first straight line.
Thereby, longitudinal vibration can be increased while reducing power consumption.

(Application example 5)
In the piezoelectric actuator according to the present invention, it is preferable that the first straight line passes through a central portion of the piezoelectric element in the vibration direction of the longitudinal vibration.

  Thereby, a 1st electrode and a 2nd electrode can be arrange | positioned in a suitable position, and a vibration can be stabilized more.

(Application example 6)
In the piezoelectric actuator according to the present invention, the direction different from the vibration direction of the longitudinal vibration is preferably a direction orthogonal to the vibration direction of the longitudinal vibration.

  Thereby, a 1st electrode and a 2nd electrode can be arrange | positioned with sufficient balance, and a vibration can be stabilized more.

(Application example 7)
In the piezoelectric actuator according to the present invention, it is preferable that the first electrode and the second electrode are provided symmetrically with respect to a predetermined second straight line extending in the vibration direction of the longitudinal vibration.
Thereby, a vibration can be stabilized more.

(Application example 8)
In the piezoelectric actuator according to the present invention, it is preferable that the plurality of electrodes are provided symmetrically with respect to a predetermined second straight line extending in the vibration direction of the longitudinal vibration.

  Thereby, when it is set as the structure which displaces a to-be-driven body to the normal / reverse direction, it can reduce that the nonuniformity arises in the drive characteristic of a to-be-driven body by the displacement direction of a to-be-driven body.

(Application example 9)
In the piezoelectric actuator according to the present invention, it is preferable that the second straight line passes through a central portion of the piezoelectric element in a direction orthogonal to the vibration direction of the longitudinal vibration.

  Thereby, a 1st electrode and a 2nd electrode can be arrange | positioned with sufficient balance, and a vibration can be stabilized more.

(Application Example 10)
In the piezoelectric actuator according to the present invention, the driven body is rotatably provided.
It is preferable that the vibration direction of the longitudinal vibration at the contact portion of the diaphragm with the driven body is a direction toward the rotation center of the driven body.

  Thereby, it can suppress that a to-be-driven body rotates when a diaphragm vibrates longitudinally.

(Application Example 11)
In the piezoelectric actuator according to the present invention, the driven body is movably provided,
It is preferable that the moving direction of the contact portion of the driven body with the diaphragm is orthogonal to the vibration direction of the longitudinal vibration.

  Thereby, it can suppress that a to-be-driven body moves when a diaphragm vibrates longitudinally.

(Application Example 12)
In the piezoelectric actuator according to the present invention, the diaphragm has a convex portion that comes into contact with the driven body,
It is preferable that the convex portion is disposed at a central portion of the diaphragm in a direction orthogonal to the vibration direction of the longitudinal vibration.

  Thereby, it can suppress that a to-be-driven body displaces when a diaphragm vibrates longitudinally.

(Application Example 13)
In the piezoelectric actuator according to the present invention, as a driving mode of the piezoelectric actuator, a first driving mode for performing the longitudinal vibration,
It is preferable to have a second drive mode that performs vibration different from the longitudinal vibration.

  Thereby, in the first driving mode, the driven body can be displaced by applying an external force to the driven body, and in the second driving mode, the driven body is displaced by the driving force of the piezoelectric actuator. be able to.

It is a top view which shows 1st Embodiment of the piezoelectric actuator of this invention. It is sectional drawing in the AA line in FIG. It is a perspective view of the vibrating body of the piezoelectric actuator shown in FIG. It is a figure of the vibrating body for demonstrating arrangement | positioning of the electrode for longitudinal vibrations of the piezoelectric actuator shown in FIG. It is a figure of the vibrating body for demonstrating operation | movement of the piezoelectric actuator shown in FIG. It is a figure of the vibrating body for demonstrating operation | movement of the piezoelectric actuator shown in FIG. It is a figure of the vibrating body for demonstrating operation | movement of the piezoelectric actuator shown in FIG. In the second embodiment of the piezoelectric actuator of the present invention, it is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrode. FIG. 10 is a diagram of a vibrating body for explaining the arrangement of longitudinal vibration electrodes in the third embodiment of the piezoelectric actuator of the present invention. FIG. 14 is a diagram of a vibrating body for explaining the arrangement of longitudinal vibration electrodes in the fourth embodiment of the piezoelectric actuator of the present invention. FIG. 20 is a diagram of a vibrating body for explaining the arrangement of longitudinal vibration electrodes in the fifth embodiment of the piezoelectric actuator of the present invention. FIG. 16 is a diagram of a vibrating body for explaining the arrangement of longitudinal vibration electrodes in the sixth embodiment of the piezoelectric actuator of the present invention. In the seventh embodiment of the piezoelectric actuator of the present invention, it is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrode. In the eighth embodiment of the piezoelectric actuator of the present invention, it is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrode. It is a top view which shows 9th Embodiment of the piezoelectric actuator of this invention.

  Hereinafter, a piezoelectric actuator of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

<First Embodiment>
FIG. 1 is a plan view showing a first embodiment of the piezoelectric actuator of the present invention. FIG. 2 is a cross-sectional view taken along line AA in FIG. FIG. 3 is a perspective view of a vibrating body of the piezoelectric actuator shown in FIG. FIG. 4 is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrodes of the piezoelectric actuator shown in FIG. FIG. 5 is a diagram of a vibrating body for explaining the operation of the piezoelectric actuator shown in FIG. FIG. 6 is a diagram of a vibrating body for explaining the operation of the piezoelectric actuator shown in FIG. FIG. 7 is a diagram of a vibrating body for explaining the operation of the piezoelectric actuator shown in FIG.

  Hereinafter, for convenience of explanation, the upper side in FIGS. 2, 3 and 4 is referred to as “upper” or “upper”, and the lower side is referred to as “lower” or “lower” (the same applies to FIGS. 8 to 14). ).

  1 to 7 show an x-axis, a y-axis, and a z-axis as three axes orthogonal to each other. A direction parallel to the x-axis is referred to as “x-axis direction”, a direction parallel to the y-axis is referred to as “y-axis direction”, and a direction parallel to the z-axis is referred to as “z-axis direction”. A plane defined by the x axis and the y axis is referred to as a “zy plane”, a plane defined by the y axis and the z axis is referred to as a “yz plane”, and a plane defined by the z axis and the x axis is referred to as “ xz plane ". Further, in the x direction, the x direction, and the z direction, the arrow tip side is defined as “+ (positive) side” and the arrow base end side is defined as “− (negative) side”. The longitudinal direction of the vibrating body, the diaphragm, the piezoelectric element, and each electrode is the x-axis direction, the lateral direction (width direction) is the y-axis direction, and the thickness direction is the z-axis direction, respectively (FIG. 8). To FIG. 15).

  Further, in FIG. 1, illustration of electrodes of the vibrating body is omitted (the same applies to FIG. 15). Moreover, in FIGS. 4-7, about the vibrating body, illustration of the connection part is abbreviate | omitted etc. and simplified (FIGS. 8-14 is also the same).

  Moreover, in FIGS. 4-7, among the electrodes of the vibrating body, the electrodes to be energized are hatched (the same applies to FIGS. 8-14).

  Moreover, in FIGS. 3 to 7, among the electrodes of the vibrating body, only the reference numerals are shown in parentheses for the electrodes that cannot be seen on the back side (the same applies to FIGS. 8 to 14).

-Basic configuration-
The piezoelectric actuator 1 supports a vibrating portion 10 having a vibrating body 2 that vibrates by application of a voltage, a rotatable (displaceable) disk-shaped rotor (driven body) 5, and the vibrating portion 10 and the rotor 5. And a support 6. In other words, the rotor 5 is a driven body having a circular cross section.

  The piezoelectric actuator 1 is a device for transmitting power (driving force) to the rotor 5 and rotating (driving) the vibrating body 2 when the vibrating body 2 vibrates. Hereinafter, each part which the piezoelectric actuator 1 has is demonstrated sequentially.

--Vibrating part 10--
The vibrating unit 10 is a vibrating unit 2, a holding unit (holding mechanism) 3 that holds the vibrating unit 2 so as to vibrate, a base 4, and a biasing unit that biases the vibrating unit 2 toward the rotor 5. A pair of leaf springs (elastic bodies) 71 and 72 are provided. In this embodiment, a pair of leaf springs (elastic bodies) 71 and 72 connect the holding portion 3 and the base 4, and a convex portion 26 (described later) of the vibrating body 2 is connected to the rotor 5 via the holding portion 3. Energize towards.

--Vibrating body 2--
The vibrating body 2 has a rectangular plate shape, and includes five electrodes 21a, 21b, 21c, 21d and 21e from the upper side of FIGS. 2 and 3, a plate-like piezoelectric element 22, a convex portion (contact portion) 26, and A diaphragm (shim) 23, which is a reinforcing plate having a pair of connecting portions 27 and 28, a plate-like piezoelectric element 24, and five electrodes 25a, 25b, 25c, 25d and 25e (in FIG. 25b and 25e are not shown in the figure, and each reference numeral is shown in parentheses) in this order. In FIGS. 2 and 3, the thickness direction is exaggerated.

  The vibrating body 2 vibrates when the piezoelectric elements 22 and 24 are deformed by application of voltage, and transmits power to the rotor 5 via the convex portion 26 to rotate the rotor 5.

  The piezoelectric elements 22 and 24 each have a rectangular shape, and are fixed to both surfaces of the diaphragm 23.

  The piezoelectric elements 22 and 24 expand or contract in the longitudinal direction when a voltage is applied, and return to their original shapes when the voltage application is stopped.

  The constituent materials of the piezoelectric elements 22 and 24 are not particularly limited, respectively. Lead zirconate titanate (PZT), crystal, lithium niobate, barium titanate, lead titanate, lead metaniobate, polyvinylidene fluoride, zinc Various materials such as lead niobate and lead scandium niobate can be used.

  On the upper surface of the piezoelectric element 22, the upper surface is substantially divided into six rectangular regions, that is, divided into two parts in the X-axis direction and three parts in the Y-axis direction. In the region, electrodes 21a, 21b, 21c and 21d each having a rectangular shape are installed. An electrode 21e having a rectangular shape that is about twice as long as the electrodes 21a, 21b, 21c, and 21d is installed across the two regions in the center of the upper surface of the piezoelectric element 22 in the Y-axis direction. The electrodes 21a, 21b, 21c, 21d and 21e are separated from each other.

  Similarly, on the lower surface of the piezoelectric element 24, the lower surface is substantially equally divided into six rectangular areas, that is, divided into two parts in the X-axis direction and three parts in the Y-axis direction. In four regions, rectangular electrodes 25a, 25b, 25c and 25d are provided, respectively. An electrode 25e having a rectangular shape about twice as long as the electrodes 25a, 25b, 25c, and 25d is provided across the two regions in the center of the lower surface of the piezoelectric element 24 in the Y-axis direction. The electrodes 25a, 25b, 25c, 25d and 25e are separated from each other.

  The electrodes 21a, 21b, 21c, 21d, and 21e are arranged in line symmetry with respect to a predetermined first straight line 91 that extends in a direction different from the vibration direction of longitudinal vibration described later, and in the vibration direction of longitudinal vibration. They are arranged symmetrically with respect to a predetermined second straight line 92 that extends. Similarly, the electrodes 25a, 25b, 25c, 25d and 25e are arranged symmetrically with respect to a predetermined first straight line 91 extending in a direction different from the vibration direction of longitudinal vibration described later, and the vibration direction of the longitudinal vibration. Are arranged symmetrically with respect to a predetermined second straight line 92 extending in a straight line.

  In this embodiment, the vibration direction 93 of the longitudinal vibration of the vibrating body 2 (the diaphragm 23) is the X-axis direction, and the direction orthogonal to the vibration direction 93 of the longitudinal vibration is the Y-axis direction. Further, the vibration direction 94 of longitudinal vibration at the contact portion of the convex portion 26 of the vibrating body 2 with the rotor 5 is a direction toward the rotation center 50 of the rotor 5. Further, the direction different from the vibration direction 93 of the longitudinal vibration is a direction orthogonal to the vibration direction 93 of the longitudinal vibration, that is, the Y-axis direction, and the first straight line 91 extends in the Y-axis direction. The first straight line 91 passes through the center of the piezoelectric elements 22 and 24 in the X-axis direction (longitudinal vibration direction 93), and the second straight line 92 extends in the Y-axis direction (longitudinal vibration direction 93). It passes through the central part of the piezoelectric elements 22 and 24 in the direction orthogonal to each other.

  In addition, the electrode 21a and the electrode 25a, the electrode 21b and the electrode 25b, the electrode 21c and the electrode 25c, the electrode 21d and the electrode 25d, and the electrode 21e and the electrode 25e are arranged to face each other in the thickness direction of the vibrating body 2. ing. Further, as shown in FIG. 3, the electrode 21a and the electrode 25a located on the back side, the electrode 21b and the electrode 25b located on the back side, the electrode 21c and the electrode 25c located on the back side, the electrode 21d and the back side are located. The electrode 25d, the electrode 21e, and the electrode 25e located on the back side thereof are electrically connected to each other.

  The diaphragm 23 has a function of reinforcing the entire vibrating body 2 and prevents the vibrating body 2 from being damaged by over-amplitude, external force, or the like. The constituent material of the diaphragm 23 is not particularly limited, but is preferably various metal materials such as stainless steel, aluminum or aluminum alloy, titanium or titanium alloy, copper or copper-based alloy.

  The diaphragm 23 is preferably thinner (smaller) than the piezoelectric elements 22 and 24. Thereby, the vibrating body 2 can be vibrated with high efficiency.

  The diaphragm 23 is grounded (connected to the ground potential), and also has a function as a common electrode for the piezoelectric elements 22 and 24. That is, a voltage is applied to the piezoelectric element 22 by a predetermined electrode among the electrodes 21a, 21b, 21c, 21d and 21e and the diaphragm 23, and the electrodes 25a, 25b, 25c and 25d are applied to the piezoelectric element 24. And a voltage is applied by the predetermined electrode of 25e and the diaphragm 23.

  In addition, without using the diaphragm 23 as a common electrode for the piezoelectric elements 22 and 24, for example, between the diaphragm 23 and the piezoelectric element 22 and between the diaphragm 23 and the piezoelectric element 24, the piezoelectric element 22 and the piezoelectric element, respectively. A common electrode for the element 24 may be further provided.

  Further, a convex portion 26 is integrally formed at one end portion (end portion on the rotor 5 side) in the longitudinal direction of the diaphragm 23. In other words, each of the piezoelectric elements 22 and 24 is provided on the opposite side of the convex portion 26 from the rotor 5.

  The convex part 26 is located in the center part of the vibrating body 2 (diaphragm 23) in the width direction (Y-axis direction), and its tip has a semicircular shape in plan view. Needless to say, the shape and position of the convex portion 26 are not limited to this.

  The convex portion 26 abuts on the rotor 5 or moves away from the rotor 5 when the vibrating body 2 vibrates.

  Further, at both ends in the width direction of the diaphragm 23, connecting portions 27 and 28 for connecting the diaphragm 23 to the holding portion 3 are integrally formed so as to vibrate the vibrating body 2. The connecting portions 27 and 28 are arranged to be symmetrical with each other on the right side and the left side of the diaphragm 23 in FIG.

  The connecting portion 27 has a rectangular shape, and is formed at an attachment portion 273 attached to the holding portion 3 to be described later, and both ends in the longitudinal direction of the attachment portion 273 so that the vibrating body 2 can vibrate, and the attachment portion of the diaphragm 23 is attached. And support portions 271 and 272 that are connected to and support the H.273. Similarly, the connecting portion 28 has a rectangular shape, and is formed at an attachment portion 283 attached to the holding portion 3 and both ends in the longitudinal direction of the attachment portion 283, and attaches the diaphragm 23 so that the vibrating body 2 can vibrate. Support portions 281 and 282 are connected to and supported by the portion 283. The support portions 271, 272, 281, and 282 are disposed at the positions of the bending vibration nodes (to be described later) of the vibrating body 2 (the diaphragm 23).

-Holding part 3-
The holding unit 3 is configured so as not to hinder the vibration of the vibrating body 2 and holds the vibrating body 2 so as to be able to vibrate. The holding portion 3 includes a pair of support columns 31 and 32 arranged so as to be separated from each other, and a connecting portion 33 that connects an upper end portion of the support column 31 and a lower end portion of the support column 32. ing. The support column 32 is arranged on the side farther from the base 4 than the support column 31, and the lower end of the support column 32 protrudes in a direction away from the support column 31.

  The vibrating body 2 is disposed between the support column 31 and the support column 32, and the mounting portion 273 of the connecting portion 27 on the left side in FIG. 1 is attached to the support column 31 by screws 115 and 117 at positions corresponding to the support portions 271 and 272. The attachment portion 283 of the connecting portion 28 on the right side in FIG. 1 is fixed to the column 31 with screws 116 and 118 at positions corresponding to the support portions 281 and 282.

  The constituent material of the holding unit 3 is not particularly limited, and for example, various metal materials, various ceramic materials, and the like can be used.

-Base 4-
The base 4 supports the holding unit 3 holding the vibrating body 2 via a pair of leaf springs 71 and 72 and is fixed to the support 6. The shape of the base 4 is not particularly limited, but in the present embodiment, the shape of the cross section is a rod having a substantially rectangular shape, that is, a substantially rectangular parallelepiped that is long in one direction.

-Leaf springs 71, 72-
The pair of leaf springs 71 and 72 are separated from each other, and connect the holding unit 3 and the base 4 with the entire holding unit 3 sandwiched therebetween. In this case, one end (left side in FIG. 1) of the leaf spring 71 is fixed to the upper end of the base 4 with a screw 111, and the other end (right side in FIG. 1) of the leaf spring 71 is The upper end of the support 31 of the holding unit 3 is fixed with screws 112. Similarly, one end (left side in FIG. 1) of the leaf spring 72 is fixed to the lower end of the base 4 with a screw 113, and the other end (right side in FIG. 1) of the leaf spring 72 is fixed. The lower end of the support column 32 of the holding unit 3 is fixed with a screw 114.

  The leaf springs 71 and 72 are elastically deformed and urge the holding portion 3 holding the vibrating body 2 toward the rotor 5. That is, the leaf springs 71 and 72 urge the convex portion 26 of the vibrating body 2 toward the rotor 5 via the holding portion 3. Thereby, the power transmission to the rotor 5 by the vibrating body 2 can be performed efficiently.

  Further, the shape of the leaf springs 71 and 72 is not particularly limited, but in the present embodiment, it has an S shape.

--Rotor 5--
The rotor 5 is disposed in front of the vibration unit 10 having such a configuration in the X-axis direction.

  The rotor 5 is held so as to be rotatable in the forward direction (clockwise) and in the negative direction (counterclockwise) that is the opposite direction, with a rod-shaped shaft portion 51 erected on the support 6 as a rotation center.

And the convex part 26 contact | abuts repeatedly on the outer peripheral surface 52 of such a rotor 5 because the vibrating body 2 vibrates.
The basic configuration of the piezoelectric actuator 1 has been described above.

--Drive--
Next, the operation of the piezoelectric actuator 1 will be described.

  The piezoelectric actuator 1 drives the piezoelectric actuator 1 as its driving mode, but the first driving mode (teaching mode) in which the rotor 5 is not rotated by the vibration of the vibrating body 2 and the piezoelectric actuator 1 is driven to drive the rotor 5. A second driving mode (normal driving mode) for rotation.

  In the first driving mode, the piezoelectric actuator 1 applies a predetermined signal to the predetermined electrode of the vibrating body 2, that is, applies a positive voltage at a constant period (energization), whereby the convex portion 26 reciprocates along the X-axis direction. Thus, the vibrating body 2 (the diaphragm 23) is vibrated (longitudinal vibration). Hereinafter, this vibration is referred to as longitudinal vibration.

  In the first drive mode, some of the electrodes 21a, 21b, 21c, 21d and 21e (hereinafter referred to as longitudinal vibration electrodes) and one of the electrodes 25a, 25b, 25c, 25d and 25e. Part of the electrode (hereinafter referred to as the longitudinal vibration electrode) is energized. The vibrator 2 vibrates longitudinally even when all of the electrodes 21a, 21b, 21c, 21d, 21e, 25a, 25b, 25c, 25d, and 25e are energized. However, when all the electrodes are energized, The impedance of the piezoelectric elements 22 and 24 at the time of resonance of the vibrating body 2 can be increased as compared with the case where current is supplied to the electrodes of the vibrating body 2, thereby stabilizing vibration and reducing power consumption. Can do.

  Hereinafter, the longitudinal vibration electrode will be further described. The arrangement of the longitudinal vibration electrodes of the electrodes 21a, 21b, 21c, 21d and 21e and the arrangement of the longitudinal vibration electrodes of the electrodes 25a, 25b, 25c, 25d and 25e are as follows. Since these are the same, hereinafter, the electrodes for longitudinal vibration in the electrodes 21a, 21b, 21c, 21d, and 21e will be described as representative examples.

  First, the longitudinal vibration electrode includes a first electrode and a second electrode that are arranged adjacent to each other in the Y-axis direction. In the present embodiment, the longitudinal vibration electrode is an electrode (first electrode). Electrode) 21a and electrode (second electrode) 21d. In this case, the electrode 21e is disposed as the third electrode between the electrode 21a and the electrode 21d in the Y-axis direction. In the present embodiment, the electrode 21e is not a longitudinal vibration electrode. As for the electrodes 25a, 25b, 25c, 25d and 25e, the longitudinal vibration electrode is composed of an electrode (first electrode) 25a and an electrode (second electrode) 25d, and the electrode 25e is the third electrode. The electrode 25e is not a longitudinal vibration electrode.

  The longitudinal vibration electrode is provided asymmetrically with respect to the first straight line 91. The electrodes 21 a and 21 d are arranged on the convex portion 26 side with respect to the first straight line 91.

  Further, the longitudinal vibration electrodes, that is, the electrode 21 a and the electrode 21 d are arranged symmetrically with respect to the second straight line 92. In the present embodiment, the electrode 21a and the electrode 21d are arranged at the left end portion and the right end portion in the drawing of the piezoelectric element 24 with the second straight line 92 as the center.

  By using the electrodes 21a and 21d as the longitudinal vibration electrodes in this way, the balance in the Y-axis direction of the force applied from the vibrating body 2 to the rotor 5 is stabilized as compared with the case where the electrode 21e is used as the longitudinal vibration electrode. Thereby, vibration can be stabilized.

  In addition, since the electrodes 21a and 21d are arranged on the convex portion 26 side (the rotor 5 side) with respect to the first straight line 91, it is possible to increase the longitudinal vibration while reducing the power consumption.

  In this first drive mode, the vibrating body 2 (the vibration plate 23) vibrates longitudinally, so that the vibrating body is compared with a case where the piezoelectric actuator 1 is not driven and is not driven (stopped). The holding force which the 2 convex part 26 acts on the rotor 5 can be reduced significantly. Thereby, when it is going to rotate the rotor 5 with external force other than the piezoelectric actuator 1, the rotor 5 can be rotated easily and reliably.

  For example, a case where the piezoelectric actuator 1 is applied to a joint drive source of a robot will be described as an example. In the first drive mode, the piezoelectric actuator 1 is driven in the second drive mode to rotate the rotor 5. When the robot performs a predetermined work, for example, the operator manually aligns the robot joints in advance by bending or extending the joints in advance (hereinafter, this work is referred to as teaching or teaching work). Used for etc. The position aligned by the teaching work is stored in a storage unit of a control device (not shown) as position information such as coordinates, for example.

  Further, in the second drive mode, the piezoelectric actuator 1 applies a predetermined signal to the predetermined electrode of the vibrating body 2, that is, applies a positive voltage at a constant period (energization), thereby causing the vibrating body 2 (the diaphragm 23) to be applied. Vibrate differently from the longitudinal vibration. In the present embodiment, the vibrating body 2 (diaphragm 23) is vibrated (bending vibration) so that the convex portion 26 has an elliptical orbit, and the rotor 5 is rotated by this vibration. Hereinafter, this vibration is referred to as bending vibration.

  In the second drive mode, some of the electrodes 21a, 21b, 21c, 21d, 21e, 25a, 25b, 25c, 25d, and 25e, in this embodiment, the electrodes 21a, 21c, 21e, 25a, and 25c. And 25e, or the electrodes 21b, 21d, 21e, 25b, 25d and 25e.

  Hereinafter, the reason why the convex portion 26 reciprocates along the X-axis direction in the first drive mode and the convex portion 26 draws an elliptical orbit in the second drive mode will be described.

-Movement of convex part-
As described above, the piezoelectric elements 22 and 24 repeat the application and release of a positive voltage (a positive charge is applied at a constant period) so that the piezoelectric elements 22 and 24 extend in the longitudinal direction and return to the original shape. (The operation of contracting from the stretched state) is repeated.

  In the first drive mode, when the electrodes 21a, 21d, 25a, and 25d are energized at a constant cycle, and a positive voltage is applied between the electrodes 21a, 21d, 25a, and 25d and the diaphragm 23 at a constant cycle. The portions corresponding to the electrodes 21a and 21d of the piezoelectric element 22 and the portions corresponding to the electrodes 25a and 25d of the piezoelectric element 24 repeat contraction and expansion.

  On the other hand, since the electrodes 21b, 21d, 21e, 25b, 25d and 25e are not energized, the portions corresponding to the electrodes 21b, 21d and 21e of the piezoelectric element 22 and the electrodes 25b, 25d and 25e of the piezoelectric element 24 It does not shrink or stretch with the part corresponding to.

  Along with such expansion and contraction, the entire vibrating body 2 performs longitudinal vibration (stretching vibration) as shown in FIG. 5 along the X-axis direction in the XY plane.

  Further, when the frequency at which the voltage is applied is changed, the amount of expansion / contraction suddenly increases when a certain frequency is reached, and a kind of resonance phenomenon occurs. The frequency (resonance frequency) at which resonance occurs due to longitudinal vibration is determined by various conditions such as the physical properties of the vibrating body 2 and the dimensions (width W, length L, thickness T) of the vibrating body 2.

  In the second drive mode, the electrodes 21 a, 21 c, 21 e, 25 a, 25 c and 25 e are energized at a constant cycle, and between these electrodes 21 a, 21 c, 21 e, 25 a, 25 c and 25 e and the diaphragm 23. When a positive voltage is applied at a constant period, the portions corresponding to the electrodes 21a, 21c and 21e of the piezoelectric element 22 and the portions corresponding to the electrodes 25a, 25c and 25e of the piezoelectric element 24 repeat contraction and expansion.

  In contrast, since the electrodes 21b, 21d, 25b and 25d are not energized, the portion corresponding to the electrodes 21b and 21d of the piezoelectric element 22 and the portion corresponding to the electrodes 25b and 25d of the piezoelectric element 24 are contracted. Do not stretch or stretch.

  Along with such extension and contraction, the entire vibrator 2 undergoes bending vibration as shown in FIG. 6 in the XY plane. That is, the bending vibration due to the expansion / contraction of the portion corresponding to the electrodes 21a and 21c of the piezoelectric element 22, the bending vibration due to the expansion / contraction of the portion corresponding to the electrodes 25a and 25c of the piezoelectric element 24, and the portion corresponding to the electrode 21e of the piezoelectric element 22 6 is combined with the vertical vibration due to the expansion and contraction of the portion corresponding to the electrode 25e of the piezoelectric element 24, and the vibration body 2 as a whole performs bending vibration as shown in FIG.

  In the second drive mode, the electrodes 21b, 21d, 21e, 25b, 25d, and 25e are energized at a constant period, and between these electrodes 21b, 21d, 21e, 25b, 25d, and 25e and the diaphragm 23, When a positive voltage is applied at a constant period, the portions corresponding to the electrodes 21b, 21d and 21e of the piezoelectric element 22 and the portions corresponding to the electrodes 25b, 25d and 25e of the piezoelectric element 24 repeat contraction and expansion.

  On the other hand, since the electrodes 21a, 21c, 25a and 25c are not energized, the portion corresponding to the electrodes 21a and 21c of the piezoelectric element 22 and the portion corresponding to the electrodes 25a and 25c of the piezoelectric element 24 are contracted. Do not stretch or stretch.

  Along with such expansion and contraction, the entire vibrator 2 undergoes bending vibration as shown in FIG. 7 in the XY plane. That is, the bending vibration due to the expansion / contraction of the portion corresponding to the electrodes 21b and 21d of the piezoelectric element 22, the bending vibration due to the expansion / contraction of the portion corresponding to the electrodes 25b and 25d of the piezoelectric element 24, and the portion corresponding to the electrode 21e of the piezoelectric element 22 The vertical vibration due to the expansion and contraction of the piezoelectric element 24 and the vertical vibration due to the expansion and contraction of the portion corresponding to the electrode 25e of the piezoelectric element 24 are combined, and the vibration body 2 as a whole performs bending vibration as shown in FIG.

  6 and 7 also have a resonance frequency determined by various properties such as the physical properties of the vibrating body 2 and the dimensions (width W, length L, thickness T) of the vibrating body 2.

  As described above, both the resonance frequency of the longitudinal vibration shown in FIG. 5 and the resonance frequency of the bending vibration shown in FIG. 6 or 7 are the physical properties of the vibrating body 2 and the dimensions (width W, length L, thickness of the vibrating body 2). S) and the like. Therefore, if the dimensions (width W, length L, thickness T) of the vibrating body 2 are appropriately selected, the resonance frequencies can be matched or brought close to each other. When a voltage in the form of bending vibration as shown in FIG. 6 or 7 is applied to such a vibrating body 2 at a resonance frequency, longitudinal vibration is further induced.

  As a result, when a voltage is applied in the manner shown in FIG. 6, the vibrating body 2 has an elliptical orbit (first elliptical orbit) with the convex portion 26 having an arrow DL (clockwise in the drawing) as shown in FIG. ) Vibrate to draw. Such vibration is referred to as a first vibration mode.

  On the other hand, when a voltage is applied in the mode shown in FIG. 7, the vibrating body 2 has an elliptical orbit (second elliptical orbit) in which the convex portion 26 has an arrow DR (counterclockwise in the drawing) as shown in FIG. ) Vibrate to draw. Such vibration is referred to as a second vibration mode.

  Although the above description has been made assuming that a positive voltage is applied to the vibrating body 2, the piezoelectric elements 22 and 24 are also deformed by applying a negative voltage. Therefore, bending vibration (and expansion / contraction vibration) may be generated by applying a negative voltage to the vibrating body 2, or bending vibration (and expansion / contraction) by applying an alternating voltage that repeats a positive voltage and a negative voltage. (Vibration) may be generated.

  In the above description, the voltage having the resonance frequency is applied. However, it is sufficient to apply a voltage having a waveform including the resonance frequency. For example, a pulse voltage may be used.

-Movement of rotor 5-
The vibrating body 2 rotates the rotor 5 using the first vibration mode or the second vibration mode in the second drive mode.

  Specifically, as shown in FIG. 6, when the vibrating body 2 is vibrated in the first vibration mode, the vibrating body 2 vibrates so that the convex portion 26 draws an elliptical orbit indicated by an arrow DL. The frictional force received from the convex portion 26 rotates counterclockwise as indicated by an arrow SR in FIG.

  On the other hand, as shown in FIG. 7, when the vibrating body 2 is vibrated in the second vibration mode, the vibrating body 2 vibrates so that the convex portion 26 draws an elliptical orbit indicated by the arrow DR as shown in FIG. The rotor 5 rotates clockwise as indicated by an arrow SL in FIG.

  In this way, the rotor 5 rotates clockwise or counterclockwise by the vibration of the vibrating body 2.

  As described above, according to the piezoelectric actuator 1, in the first driving mode, the vibrating body 2 vibrates in the longitudinal direction, so that the rotor 5 is not displaced and compared with the non-driving state. The holding force that the convex portion 26 of the vibrating body 2 acts on the rotor 5 can be significantly reduced. As a result, when the rotor 5 is to be rotated by an external force other than the piezoelectric actuator 1, the rotor 5 can be easily and reliably rotated. Thus, for example, when the piezoelectric actuator 1 is applied to a robot and used as a drive source for a joint of the robot, when the robot is taught, the vibrating body 2 is vibrated longitudinally so that it can be easily and reliably applied by an external force. In addition, the robot joint can be bent or extended, so that the teaching can be performed easily and reliably.

  Also, by using the electrodes 21a and 21b as the longitudinal vibration electrodes, the balance in the Y-axis direction of the force applied from the vibrating body 2 to the rotor 5 is stabilized compared to the case where the electrode 21e is used as the longitudinal vibration electrode. Thus, vibration can be stabilized.

  In addition, the impedance of the piezoelectric elements 22 and 24 at the time of resonance of the vibrating body 2 can be increased compared with the case where the vibrating body 2 is longitudinally vibrated by energizing all the electrodes, thereby stabilizing the vibration. In addition, power consumption can be reduced.

Second Embodiment
FIG. 8 is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrodes in the second embodiment of the piezoelectric actuator of the present invention.

  Hereinafter, the second embodiment will be described with a focus on the differences from the first embodiment described above, and the description of the same matters will be omitted. Similarly to the first embodiment, as for the longitudinal vibration electrodes, the longitudinal vibration electrodes in the electrodes 21a, 21b, 21c, 21d, and 21e will be described typically.

As shown in FIG. 8, in the piezoelectric actuator 1 of the second embodiment, the longitudinal vibration electrodes are the electrode (first electrode) 21 a, the electrode (first electrode) 21 b, the electrode (second electrode) 21 c, It is comprised with the electrode (2nd electrode) 21d.
According to the second embodiment, the same effects as those of the first embodiment described above can be obtained.

<Third Embodiment>
FIG. 9 is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrodes in the third embodiment of the piezoelectric actuator of the present invention.

  Hereinafter, the third embodiment will be described with a focus on differences from the first embodiment described above, and descriptions of the same matters will be omitted. Similarly to the first embodiment, as for the longitudinal vibration electrodes, the longitudinal vibration electrodes in the electrodes 21a, 21b, 21c, 21d, and 21e will be described typically.

As shown in FIG. 9, in the piezoelectric actuator 1 according to the third embodiment, the longitudinal vibration electrodes are an electrode (first electrode) 21a, an electrode (second electrode) 21d, and an electrode (third electrode) 21e. It is configured. The electrode 21e has a portion located between the electrode 21a and the electrode 21d in the Y-axis direction. That is, almost half of the electrode 21e on the convex portion 26 side is disposed between the electrode 21a and the electrode 21d in the Y-axis direction.
According to the third embodiment, the same effects as those of the first embodiment described above can be obtained.

<Fourth embodiment>
FIG. 10 is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrodes in the fourth embodiment of the piezoelectric actuator of the present invention.

  Hereinafter, the fourth embodiment will be described focusing on the differences from the first embodiment described above, and description of similar matters will be omitted. Similarly to the first embodiment, as for the longitudinal vibration electrodes, the longitudinal vibration electrodes in the electrodes 21a, 21b, 21c, 21d, and 21e will be described typically.

As shown in FIG. 10, in the piezoelectric actuator 1 of the fourth embodiment, the longitudinal vibration electrodes are an electrode (first electrode) 21 b, an electrode (second electrode) 21 c, and an electrode (third electrode) 21 e. It is configured. The electrode 21e has a portion located between the electrode 21a and the electrode 21d in the Y-axis direction. That is, almost half of the electrode 21e opposite to the convex portion 26 is disposed between the electrode 21b and the electrode 21c in the Y-axis direction.
According to the fourth embodiment, the same effects as those of the first embodiment described above can be obtained.

<Fifth Embodiment>
FIG. 11 is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrodes in the fifth embodiment of the piezoelectric actuator of the present invention.

  Hereinafter, the fifth embodiment will be described with a focus on differences from the first embodiment described above, and descriptions of similar matters will be omitted. Similarly to the first embodiment, as for the longitudinal vibration electrodes, the longitudinal vibration electrodes in the electrodes 21a, 21b, 21c, 21d, 21f, and 21g will be described typically.

  As shown in FIG. 11, in the piezoelectric actuator 1 of the fifth embodiment, the piezoelectric element 22 is provided with six electrodes 21a, 21b, 21c, 21d, 21f and 21g, and the piezoelectric element 24 is provided with six electrodes 25a, 25b, 25c, 25d, 25f and 25g are provided. The electrodes 21f and 21g are provided by equally dividing the electrode 21e of the first embodiment into two. Similarly, the electrodes 25f and 25g are provided by equally dividing the electrode 25e of the first embodiment into two. Therefore, in the second drive mode, the electrodes 21f and 21g are energized instead of energizing the electrode 21e.

The longitudinal vibration electrode is composed of an electrode (first electrode) 21a, an electrode (second electrode) 21d, and an electrode (third electrode) 21f. The entire electrode 21f is disposed between the electrode 21a and the electrode 21d in the Y-axis direction.
According to the fifth embodiment, the same effects as those of the first embodiment described above can be obtained.

<Sixth Embodiment>
FIG. 12 is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrodes in the sixth embodiment of the piezoelectric actuator of the present invention.

  Hereinafter, the sixth embodiment will be described with a focus on differences from the above-described fifth embodiment, and description of similar matters will be omitted. Similarly to the fifth embodiment, as for the longitudinal vibration electrodes, the longitudinal vibration electrodes in the electrodes 21a, 21b, 21c, 21d, 21f, and 21g will be described typically.

As shown in FIG. 12, in the piezoelectric actuator 1 of the sixth embodiment, the longitudinal vibration electrodes are an electrode (first electrode) 21a, an electrode (first electrode) 21b, an electrode (second electrode) 21c, It consists of an electrode (second electrode) 21d and an electrode (third electrode) 21f. The entire electrode 21f is disposed between the electrode 21a and the electrode 21d in the Y-axis direction.
According to the fifth embodiment, the same effects as those of the first embodiment described above can be obtained.

<Seventh embodiment>
FIG. 13 is a diagram of a vibrating body for explaining the arrangement of the longitudinal vibration electrodes in the seventh embodiment of the piezoelectric actuator of the present invention.

  Hereinafter, the seventh embodiment will be described with a focus on differences from the above-described fifth embodiment, and description of similar matters will be omitted. Similarly to the fifth embodiment, as for the longitudinal vibration electrodes, the longitudinal vibration electrodes in the electrodes 21a, 21b, 21c, 21d, 21f, and 21g will be described typically.

As shown in FIG. 13, in the piezoelectric actuator 1 of the seventh embodiment, the longitudinal vibration electrodes are an electrode (first electrode) 21 a, an electrode (second electrode) 21 d, an electrode (third electrode) 21 f, It is comprised with the electrode 21g. The entire electrode 21f is disposed between the electrode 21a and the electrode 21d in the Y-axis direction.
According to the seventh embodiment, the same effect as that of the fifth embodiment described above can be obtained.

<Eighth Embodiment>
FIG. 14 is a view of a vibrating body for explaining the arrangement of the longitudinal vibration electrodes in the eighth embodiment of the piezoelectric actuator of the present invention.

  Hereinafter, the eighth embodiment will be described focusing on differences from the above-described fifth embodiment, and description of similar matters will be omitted. Similarly to the fifth embodiment, as for the longitudinal vibration electrodes, the longitudinal vibration electrodes in the electrodes 21a, 21b, 21c, 21d, 21f, and 21g will be described typically.

As shown in FIG. 14, in the piezoelectric actuator 1 of the eighth embodiment, the longitudinal vibration electrodes are the electrode (first electrode) 21a, the electrode (first electrode) 21b, the electrode (second electrode) 21c, It consists of an electrode (second electrode) 21d and an electrode (third electrode) 21g. The entire electrode 21g is disposed between the electrode 21b and the electrode 21c in the Y-axis direction.
According to the eighth embodiment, the same effects as those of the fifth embodiment described above can be obtained.

<Ninth Embodiment>
FIG. 15 is a plan view showing a ninth embodiment of the piezoelectric actuator of the present invention.

  Hereinafter, the ninth embodiment will be described focusing on the differences from the first embodiment described above, and description of similar matters will be omitted.

  As shown in FIG. 15, the piezoelectric actuator 1 of the second embodiment includes a driven body having a longitudinal cross-sectional shape, that is, a slider 8 instead of the rotor 5 as a driven body.

  The slider 8 has a rod shape with a substantially square cross section, that is, a substantially rectangular parallelepiped that is long in one direction, and is installed to be movable (displaceable) in the longitudinal direction (axial direction). The piezoelectric actuator 1 is a device that transmits (drives) power (driving force) to the slider 8 when the vibrating body 2 vibrates. The movement direction 96 of the contact portion of the protrusion 2 of the vibrating body 2 of the slider 8, the vibration direction 93 of the longitudinal vibration of the vibration body 2, and the longitudinal vibration at the contact portion of the protrusion 26 of the vibration body 2 with the slider 8. The vibration direction 94 is orthogonal.

  The slider 8 is provided with two rollers 80a and 80b and two convex portions (movement restricting means) 83a and 83b that restrict the movement of the slider 8.

  The two rollers 80a and 80b are arranged in parallel in the left-right direction in FIG. The two rollers 80a and 80b are respectively arranged on one side (upper side in FIG. 15) of the slider 8 with shafts 81a and 81b positioned in the center in a posture parallel to the slider 8 and rotatable in both forward and reverse directions. It is supported.

  Further, grooves 82a and 82b are formed along the outer periphery on the peripheral surfaces (outer peripheral surfaces) of the rollers 80a and 80b, respectively. The slider 8 is disposed (positioned) in the groove 82a of the roller 80a and the groove 82b of the roller 80b.

  Further, the convex portion 83a is positioned at the left end portion in FIG. 15 with respect to the eight slider roller 80a, and the convex portion 83b is positioned at the right end portion in FIG. 15 with respect to the roller 80b of the slider 8.

  In addition, the position and number of convex parts are not restricted to this, For example, you may arrange | position between the two rollers 80a and 80b, and the number of convex parts may be one. Further, the number of rollers is not limited to this.

According to the ninth embodiment, the same effects as those of the first embodiment described above can be obtained.
The ninth embodiment can also be applied to the second to eighth embodiments described above.

  Although the piezoelectric actuator of the present invention has been described based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is replaced with an arbitrary configuration having the same function. be able to. In addition, any other component may be added to the present invention.

  Further, the present invention may be a combination of any two or more configurations (features) of the above embodiments.

  In the embodiment, the number of electrodes provided on one surface (surface opposite to the diaphragm) of one piezoelectric element is five or six. However, the present invention is not limited to this. For example, seven or more may be sufficient.

  Moreover, in the said embodiment, although the leaf | plate spring was used as an urging | biasing part, in this invention, it is not limited to this, For example, you may use a coil spring etc.

  In the above embodiment, the rotor and the slider are exemplified as the driven body. However, the driven body is not limited to this in the present invention. As a rotatable driven body, the shape of the cross section is not limited to the circular shape, and examples thereof include a polygon such as a decagon. Moreover, as a movable to-be-driven body, the shape of the cross section is not limited to the rectangle long in the said one direction, For example, the curved rod shape etc. are mentioned. Further, the driven body may be a rigid body or may have flexibility.

  Further, the use of the piezoelectric actuator of the present invention is not particularly limited, and the piezoelectric actuator of the present invention is a predetermined part of various devices such as driving of joints of various robots, driving of various end effectors such as hands. Can be used for driving.

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric actuator 10 ... Vibration part 2 ... Vibrating body 21a, 21b, 21c, 21d, 21e, 21f, 21g ... Electrode 22, 24 ... Piezoelectric element 23 ... Diaphragm 25a, 25b, 25c, 25d, 25e, 25f, 25g ... Electrode 26 ... Convex part 27, 28 ... Connection part 271, 272, 281, 282 ... Support part 273, 283 ... Attachment part 3 ... Holding part 31, 32 ... Column 33 ... Connection part 4 ... Base 5 ... Rotor 50 ... Rotation center 51: Shaft portion 52 ... Outer peripheral surface 6 ... Supports 71, 72 ... Leaf spring 8 ... Slider 80a, 80b ... Roller 81a, 81b ... Shaft 82a, 82b ... Groove 83a, 83b ... Protruding portion 91, 92 ... Straight line 93 94 ... vibrating direction 96 ... moving direction 111-118 ... screw

Claims (13)

A piezoelectric element provided with a plurality of electrodes;
A diaphragm that vibrates at least longitudinally by applying a signal to the piezoelectric element;
A driven body that comes into contact with the diaphragm,
When causing the diaphragm to vibrate longitudinally, the signal is applied to at least the first electrode and the second electrode of the plurality of electrodes,
A piezoelectric actuator, wherein a third electrode is disposed between the first electrode and the second electrode in a direction different from the vibration direction of the longitudinal vibration.   2. The piezoelectric actuator according to claim 1, wherein the first electrode and the second electrode are provided asymmetrically with respect to a predetermined first straight line extending in a direction different from the vibration direction of the longitudinal vibration.   The piezoelectric actuator according to claim 1, wherein the plurality of electrodes are provided in line symmetry with respect to a predetermined first straight line extending in a direction different from the vibration direction of the longitudinal vibration. The diaphragm has a convex portion that comes into contact with the driven body,
4. The piezoelectric actuator according to claim 2, wherein the first electrode and the second electrode are arranged closer to the convex portion than the first straight line. 5.   5. The piezoelectric actuator according to claim 2, wherein the first straight line passes through a central portion of the piezoelectric element in a vibration direction of the longitudinal vibration.   6. The piezoelectric actuator according to claim 1, wherein the direction different from the vibration direction of the longitudinal vibration is a direction orthogonal to the vibration direction of the longitudinal vibration.   7. The piezoelectric device according to claim 1, wherein the first electrode and the second electrode are provided symmetrically with respect to a predetermined second straight line extending in a vibration direction of the longitudinal vibration. Actuator.   The piezoelectric actuator according to any one of claims 1 to 7, wherein the plurality of electrodes are provided in line symmetry with respect to a predetermined second straight line extending in a vibration direction of the longitudinal vibration.   The piezoelectric actuator according to claim 7 or 8, wherein the second straight line passes through a central portion of the piezoelectric element in a direction orthogonal to a vibration direction of the longitudinal vibration. The driven body is rotatably provided,
10. The piezoelectric actuator according to claim 1, wherein a vibration direction of the longitudinal vibration at a contact portion of the vibration plate with the driven body is a direction toward a rotation center of the driven body. The driven body is provided to be movable,
The piezoelectric actuator according to any one of claims 1 to 9, wherein a moving direction of a contact portion of the driven body with the diaphragm is orthogonal to a vibration direction of the longitudinal vibration. The diaphragm has a convex portion that comes into contact with the driven body,
The piezoelectric actuator according to any one of claims 1 to 11, wherein the convex portion is disposed at a central portion of the diaphragm in a direction orthogonal to a vibration direction of the longitudinal vibration. As a drive mode of the piezoelectric actuator, a first drive mode for performing the longitudinal vibration,
The piezoelectric actuator according to claim 1, further comprising: a second drive mode that performs vibration different from the longitudinal vibration.

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