JP2019071743A - Laminated piezoelectric element for ultrasonic motor and the ultrasonic motor - Google Patents

Abstract

To provide a laminated piezoelectric element for an ultrasonic motor with suppressed occurrence of a short circuit.SOLUTION: Piezo electric elements (10u and 10d) for one layer are laminated in n layers with the lowest layer as a first layer, and each piezo electric element includes an A-phase region 12a and a B-phase region 12b to which A-phase and B-phase driving signals are applied. Surfaces of piezo electric elements that face each other between layers upwards with a lower surface 214 of the first layer as a ground surface 200g are sequentially positioned in the order of a driving surface 200s and the ground surface. Between layers where driving surfaces face each other, a circular arc-shaped A-phase signal electrode 24a and a B-phase signal electrode 24b are symmetrically formed on a surface of one of the piezo electric elements. Between layers where ground surfaces face each other, a C-shaped ground electrode 21 is formed on the surface of one piezo electric element. A conductive passage of a driving signal from a driving surface of the interlayer to an upper surface 211 of an n-th layer and a ground passage from the ground surface of the interlayer to the upper surface of the n-th layer or the lower surface of the first layer are formed via terminal electrodes (22a and 22b) and side surface electrodes (23a and 23b), which are formed on prescribed piezo electric elements.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a multilayer piezoelectric element for an ultrasonic motor, and an ultrasonic motor.

  As well known, a traveling waveform ultrasonic motor (hereinafter referred to as an ultrasonic motor) generates traveling waves in the circumferential direction on a stator made of a metallic elastic body attached to a disk-like or annular piezoelectric element. The rotor is rotated by transmitting the traveling wave to the rotor via frictional force. And, compared with a motor using an electromagnet, it has features such as high torque at low speed, high speed response, holding of torque at stop, quietness, and no generation of magnetic noise. The basic structure and principle of the ultrasonic motor are described in the following non-patent documents 1 and 2.

  By the way, a piezoelectric element constituting an ultrasonic motor usually has a structure in which electrodes are formed on both front and back sides of a single (hereinafter, also referred to as a single layer) disk-like or annular piezoelectric material. . However, in an ultrasonic motor using a piezoelectric element (hereinafter, also referred to as a single-layer piezoelectric element) consisting of a single-layer piezoelectric material, it is necessary to drive at a high voltage to obtain a large mechanical amplitude. . Therefore, there has been proposed an ultrasonic motor capable of driving at a low voltage by using a multi-layer piezoelectric element in which a plurality of single-layer piezoelectric elements for one layer are laminated. And the following patent document 1 is described about the vibration wave motor corresponded to the ultrasonic wave motor using the lamination type piezoelectric element.

JP, 2014-17908, A

Shinwa Shoji Co., Ltd., "Ultrasonic motor catalog", [online], [search on September 21, 2017], Internet <URL: http://www.shinwa-syoji.com/others/img/motor. pdf> Japan Ceramics Association, "Ceramics Archives" Ultrasonic Motor "", [online], [search on September 21, 2017], Internet <URL: http://www.ceramic.or.jp/museum/ contents / pdf / 2007_6_02.pdf>

  As described above, the ultrasonic motor using the laminated piezoelectric element can be driven at a low voltage. By the way, in the single layer type piezoelectric element constituting each layer of the laminated type piezoelectric element, a signal electrode to which a drive signal for generating a traveling wave is applied is formed on one surface of the front and back, and a ground electrode is formed on the other surface. It is formed. Here, assuming that the normal direction of the single-layer piezoelectric element is the vertical direction, in a multi-layer piezoelectric element in which a plurality of layers of piezoelectric materials for one layer are vertically stacked, each of the plurality of single-layer piezoelectric elements The signal electrodes formed on the ground and the ground electrodes are connected in the vertical direction. The electrodes on the inner layer side of the laminated piezoelectric element can not be directly connected to the external circuit, so it is necessary to form some wiring up to the surface layer of the laminated piezoelectric element. In the conventional laminated piezoelectric element, the ground electrode and the signal electrode of each single-layer piezoelectric element are formed up to the peripheral edge of the surface of the piezoelectric body, and metal paste (such as silver paste) on the end face of the plate-like piezoelectric body Is applied. For example, in the vibration wave motor described in Patent Document 1, an electromechanical transducer element laminate corresponding to a laminate type piezoelectric element is formed by laminating three single layer electromechanical transducer elements corresponding to a single layer type piezoelectric element. . In each single-layer electromechanical transducer, an annular common electrode pattern corresponding to a ground electrode is formed on one surface and a fan-like drive signal application electrode pattern corresponding to a signal electrode on the other surface. Multiple are formed along the. Then, the stator contacts the lower surface of the electromechanical transducer element laminate, the common electrode pattern is formed on the lower surface, and the drive signal application electrode pattern, the common electrode pattern, and the drive signal application electrode pattern are sequentially directed toward the upper surface. It will be arranged. The same kind of electrode patterns formed on each single-layer electromechanical transducer are connected in the vertical direction via the metal paste applied to the end face.

  However, in the vibration wave motor described in Patent Document 1, the metal paste having viscosity is applied so as to straddle the layers of the single-layer electromechanical transducer elements stacked on each other. Therefore, for example, when the metal paste connecting the drive signal application electrode patterns in the stacking direction penetrates the interlayer of the single layer electromechanical transducer, if there is a positional deviation in the common electrode pattern, the metal paste becomes the common electrode pattern There is a possibility that the drive signal application electrode pattern and the common electrode pattern may be short-circuited. In addition, even if the common electrode pattern is not misaligned, short circuiting may still occur if the metal paste deeply penetrates between the layers. Even if the drive signal application electrode pattern and the common electrode pattern are not short-circuited, if a metal paste enters the layer, a drive signal is applied when a high voltage is applied to vibrate the electromechanical transducer element laminate with a large amplitude. A discharge may occur between the metal paste connected to one of the electrode pattern and the common electrode pattern and the other electrode pattern. If a discharge occurs, the heat generated during the discharge may melt the adhesive or the electrode pattern between the layers, and the like, and may damage the electromechanical transducer element laminate.

  An object of the present invention is to provide a laminated piezoelectric element in which a short circuit between the signal electrode and the ground electrode and a discharge do not easily occur, and an ultrasonic motor using the laminated piezoelectric element.

One aspect of the present invention for achieving the above object is a laminated piezoelectric element disposed in a state in which a stator of an ultrasonic motor contacts downward.
A single layer type piezoelectric element for one layer consisting of one flat plate-like piezoelectric material is laminated by n layers in the vertical direction, where n is an integer of 2 or more,
In the single-layer type piezoelectric element, the A-phase region and the B-phase region to which the respective A-phase and B-phase drive signals whose phases are shifted by 90 ° are applied to the piezoelectric body in the vertical direction are outside the predetermined range. Arranged in an arc along an annular ring having a diameter and an inner diameter,
The one direction orthogonal to the vertical direction is the front and back direction, and the direction orthogonal to the vertical direction and the front and back direction is the horizontal direction.
The A-phase region and the B-phase region are divided and arranged in a region of a central angle θ1 so as to be symmetrical with respect to a straight line in the front-rear direction which bisects the surface of the annular ring.
A plurality of fan-shaped polarization regions divided at a predetermined central angle θ2 along the annular ring are disposed in the A-phase region and the B-phase region,
The polarization polarity of the polarization region is symmetrical with respect to a straight line in the front-rear direction, and in the A phase region and the B phase region, polarization polarities of adjacent polarization regions are opposite to each other,
In the single-layer piezoelectric element of each layer, polarization regions of the same polarization polarity are arranged at the same position when viewed from above,
One of the front and back surfaces of the single-layer piezoelectric element is a ground surface to which the A phase region and the B phase region are grounded, and the other surface is an A phase in the A phase region and the B phase region. Drive surface to which a signal and a B-phase signal are applied,
The lowermost single-layer piezoelectric element is a first layer, the uppermost single-layer piezoelectric element is an n-th layer, and k is a natural number.
The upper surface of the 2k-1 layer and the lower surface of the 2k layer are the drive surface, and the upper surface of the 2k layer and the lower surface of the 2k + 1 layer are the ground surface,
One of the drive surfaces of two single-layer piezoelectric elements in which the drive surfaces face each other in the vertical direction, and the upper surface of the n-th layer when n = 2k includes the A-phase region, An arc-shaped A-phase signal electrode along the arc, and an arc-shaped B-phase signal electrode along the ring including the B-phase region,
Before and after the A-phase region and the B-phase region on one of the ground planes of the two single-layer piezoelectric elements facing each other in the vertical direction and the top surface of the nth layer when n = 2k + 1 A continuous C-shaped ground electrode is formed along the circular ring leaving one gap,
In the case of n ≧ 3, one of the drive surfaces of the two single-layer piezoelectric elements whose drive surfaces face each other in the vertical direction, and the upper surface of the nth layer and the lower surface of the first layer when n = 2k + 1. On the other hand, fan-like grounding terminal electrodes are formed in the other front and rear gaps separating the A phase region and the B phase region,
In each layer other than the first layer, an A-phase terminal electrode and a B-phase terminal electrode are formed in one of the front and back gaps separating the A-phase region and the B-phase region on the ground plane. An A-phase side electrode and a B-phase side electrode for connecting the end faces of the A-phase terminal electrode, the A-phase terminal electrode on the drive surface and the electrodes formed at positions facing the B-phase terminal electrode respectively;
The n-th A-phase signal electrode and the B-phase signal electrode when n = 2 k, or the n-th phase A-phase terminal electrode and the B-phase terminal electrode when n = 2 k + 1, and the first The A phase region of the drive surface of the first to nth layers and the electrodes formed in each of the B phase regions are connected via the A phase side electrode and the B phase side electrode,
In the case of n 単 層 3, in the single-layer piezoelectric element in which the ground terminal electrode is formed on the drive surface, the ground terminal electrode is separated from the A phase region and the B phase region on the ground surface. A side electrode for grounding is formed to connect the end face to the electrode formed in the other front and rear gap, and is formed in the other front and back region separating the A phase region and the B phase region in the ground plane of each layer. Connected to the active electrode via the ground terminal,
The present invention is a multilayer piezoelectric element for an ultrasonic motor characterized by

Further, one of the front and back surfaces is a polarization pattern surface in which a signal electrode for polarization is formed on the surface of each of the plurality of polarization regions, and the other surface is along the ring while including the A phase region. A polarized ground surface on which an arc-shaped polarization ground electrode for A phase and an arc ground polarization electrode for B phase along the annular ring are formed, including the B phase region,
The A-phase signal electrode and the B-phase signal electrode are a polarization ground electrode for the A-phase and a polarization ground electrode for the B-phase, which are formed on the polarization ground plane,
The ground electrode is formed by connecting the signal electrode for polarization formed on the polarization drive surface in the C shape by a conductor.
It may be a laminated piezoelectric element for an ultrasonic motor.

  Furthermore, in the two single-layer piezoelectric elements in which n ≧ 3 and the polarization pattern faces face each other in the vertical direction, the polarization signal electrode is formed of a thin film, and the two single-layer piezoelectric elements A multilayer piezoelectric element for an ultrasonic motor can also be provided in which the A-phase signal electrode and the B-phase signal electrode of thin film are formed on the surface layer of one polarization pattern surface.

Or n ≧ 3 and
A first single-layer piezoelectric element and a second single-layer piezoelectric element,
In the first single-layer piezoelectric element, one of the front and back surfaces is a polarization pattern surface in which a polarization signal electrode is formed on each surface of the plurality of polarization regions, and the other surface is an A-phase region. An arc-shaped polarization ground electrode for A phase along the ring while including it, and a polarization ground electrode for polarization B for the B phase along the ring while including the B phase region are formed Polarized ground plane,
In the second single-layer piezoelectric element, one of the front and back surfaces is a polarization pattern surface in which a polarization signal electrode is formed on each surface of the plurality of polarization regions, and the other surface is the A phase region A polarized ground surface on which a C-shaped polarization ground electrode continuous in an arc shape is formed along the annular ring, leaving one of the front and back gaps separating the B phase region,
The first layer is the first single-layer piezoelectric element,
When k ≧ 2, the 2k-1 layer is the second single-layer piezoelectric element, and the 2k layer is the first single-layer piezoelectric element.
When the uppermost surface which is the upper surface of the nth layer is the ground plane, the polarization signal electrode on the uppermost surface is connected by a conductor and formed on the C-shaped ground electrode,
When the uppermost surface is the drive surface, the predetermined polarization signal electrode on the uppermost surface is connected by a conductor, and the A-phase signal electrode and the B-phase signal electrode are formed.
It can also be set as a lamination type piezoelectric element for ultrasonic motors.

  The laminated piezoelectric element provided with the signal electrode for polarization and the ground electrode for polarization is more preferable if the side electrode is baked silver formed by baking silver paste.

In the stacked piezoelectric device according to any one of the above,
A flexible wiring board is disposed between the layers,
In an interlayer in which two single-layer piezoelectric elements face each other on the drive surface, two arcs are formed on the front and back sides of the flexible wiring board so as to face each of the A phase region and the B phase region. And the respective arc-shaped wiring patterns are drawn out of the layers,
In a layer in which two single-layer piezoelectric elements face each other at the ground plane, a C-shape in which a rear gap separating the A-phase region and the B-phase region is opened on both the front and back sides of the flexible wiring board And a portion of the wiring pattern is drawn out of the layer,
The two arc-shaped wiring patterns formed on the front surface and the back surface of the flexible wiring board, and the C-shaped wiring pattern are connected by a wiring member.
It can also be set as a lamination type piezoelectric element for ultrasonic motors.

  The scope of the present invention also includes an ultrasonic motor in which a stator is bonded to the lower surface of any one of the above-described multilayer piezoelectric elements. Further, in the ultrasonic motor, it is more preferable if the laminated piezoelectric element and the stator are bonded by an adhesive to which a filler having conductivity is added.

  According to the present invention, a multilayer piezoelectric element for an ultrasonic motor that hardly generates a short circuit or a discharge between a signal electrode and a ground electrode, and an ultrasonic motor using the multilayer piezoelectric element are provided. Other effects will be clarified in the following description.

It is a figure for demonstrating arrangement | positioning of the polarization area | region of the lamination type piezoelectric element for ultrasonic motors concerning the Example of this invention. It is a figure which shows the structure of the electrode used in order to form the said polarization area | region. It is a figure which shows the external appearance of the lamination type piezoelectric element which concerns on the 1st Example of this invention. It is a figure which shows the electrode structure of the lamination type piezoelectric element which concerns on the said 1st Example. It is a figure which shows the electrode structure of the lamination type piezoelectric element which concerns on the 2nd Example of this invention. It is a figure which shows the electrode structure in the modification of the lamination type piezoelectric element which concerns on the 2nd Example of this invention. It is a figure which shows the electrode structure in the other modification of the lamination type piezoelectric element which concerns on the 2nd Example of this invention. It is a figure which shows the electrode structure of the lamination type piezoelectric element which concerns on the other Example of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings used in the following description, the same or similar parts may be denoted by the same reference numerals and redundant description may be omitted. In the drawings, unnecessary reference numerals may be omitted depending on the drawing.

=== Polarized state of single-layer piezoelectric element ===
<Polarization region>
The multilayer piezoelectric element according to the embodiment of the present invention is formed by laminating a plurality of flat single-layer piezoelectric elements. In the single-layer piezoelectric element, a plurality of fan-shaped polarized regions are annularly arranged on a flat plate-shaped piezoelectric body. When the lamination direction of the single-layer piezoelectric element in the multi-layer piezoelectric element is the vertical direction, all the single-layer piezoelectric elements constituting one multi-layer piezoelectric element have the same polarization state as viewed from above and below. FIG. 1 shows an example of the polarization state of the single-layer piezoelectric element 10. The single-layer piezoelectric element 10 is formed of an annular piezoelectric body 11 of a predetermined size (for example, an outer diameter of 62 mm, an inner diameter of 42 mm, and a thickness of 0.1 mm). The drive signal of phase B and the drive signal of phase B are applied to the arc-shaped A-phase region 12a and the B-phase region 12b having a central angle θ1. The A-phase region 12a and the B-phase region 12b are arranged so as to be line symmetrical with respect to a straight line 100 which bisects the ring, that is, a predetermined straight line 100 including the diameter of the ring. A plurality of fan-shaped polarized regions 13 each having a central angle of θ2 is formed in each of the A-phase region 12a and the B-phase region 12b. In the figure, each polarization area 13 is shown by a dot pattern. Hereinafter, the extension direction of the predetermined straight line 100 is referred to as the front-rear direction, and the normal direction of the flat plate-like piezoelectric body 11 (in the figure, the depth direction in the drawing) is referred to as the up-down direction. And the direction orthogonal to the up-down direction and the front-back direction is taken as the left-right direction. Therefore, the front and back surfaces of the piezoelectric body 11 are flat surfaces including the front-rear direction and the left-right direction.

  In the single-layer piezoelectric element 10 shown in FIG. 1, each of the A-phase and B-phase regions (12a, 12b) is divided into ten polarization regions 13. Here, assuming that the normal direction to the front and back surfaces of the flat plate-like piezoelectric body 11 is the vertical direction, each polarization region 13 is polarized in the vertical direction. In each of the A-phase and B-phase regions (12a, 12b), the polarization directions of the adjacent polarization regions (13, 13) are opposite to each other. In addition, in FIG. 1, the polarity of the polarization direction which goes to the up-and-down other from up-and-down one is set to "+", and the opposite direction is made "-". Furthermore, for example, in the case of a polarized region 13 that belongs to the A-phase region 12 a and has a positive polarization polarity, this region is marked as “A +”. That is, in the single-layer piezoelectric element 10, four types of polarization regions 13 of "A +", "A-", "B +" and "B-" are present. Although the A-phase region 12a and the B-phase region 12b of the single-layer piezoelectric element 10 shown in FIG. 1 are line symmetrical with respect to the front-rear direction, they are not line symmetrical with respect to the left-right direction. There is a difference in the magnitude of the central angle of the gap (101, 102) separating the A phase region 12a and the B phase region 12b arranged in

  In order to obtain the polarization state shown in FIG. 1, an electric field in the vertical direction may be applied to each polarization region 13 of the piezoelectric body 11. The procedure of the polarization process is the same as that of the single-layer piezoelectric element in the conventional multilayer piezoelectric element. However, in the multilayer piezoelectric element according to the embodiment of the present invention, the structure of the electrode used when forming the polarized region in the single layer type piezoelectric element 10, and the A phase region 12a and the B phase region in the multilayer piezoelectric element 12b, an electrode structure for applying an A-phase drive signal (hereinafter, also referred to as an A-phase signal) and a B-phase drive signal (hereinafter, also referred to as a B-phase signal) Are different. In the following, first, the structure of the electrodes formed to obtain the polarization state shown in FIG. 1 will be described, and then the shapes of various electrodes for driving the laminated piezoelectric element, the connection structure between the electrodes, etc. Will be explained.

<Electrode for polarization treatment>
FIG. 2 is a view showing an example of the structure of an electrode used in the polarization treatment for forming the polarized region 13 formed in the single-layer piezoelectric element 10. As shown in FIG. FIGS. 2A and 2B respectively show an example of the structure of the electrodes (14 to 16) formed on the front and back surfaces and the other surface of the single-layer type piezoelectric element 10 during polarization processing. FIG. In FIGS. 2A and 2B, the electrodes (14 to 16) formed in the single-layer piezoelectric element 10 are indicated by different hatchings according to applications.

  As shown in FIG. 2A, on the front and back surface 111 of the piezoelectric body 11, an arc-shaped A-phase region 12a and a B-phase of a central angle θ1 disposed symmetrically with respect to the straight line 100 in the front-rear direction. In each of the regions 12 b, ten electrodes each having a central angle θ 2 (hereinafter, also referred to as a polarization signal electrode 14) are formed. Further, fan-shaped electrodes (hereinafter also referred to as terminal electrodes 15) having a central angle θ3 are also formed in the gaps (101, 102) separating the A-phase region 12a and the B-phase region 12b.

  Although the A-phase region 12a and the B-phase region 12b are symmetrical in the left-right direction, they are not symmetrical in the front-rear direction, but the width of the gap (101, 102) separating the A-phase region 12a and the B-phase region 12b arranged on the ring There is a difference, and in the illustrated example, only one terminal electrode 15 having a central angle θ3 is disposed at one of the front and rear gaps 101, and three terminal electrodes 15 are disposed at the other front and rear gap 102. Here, in the single-layer piezoelectric element 10, the surface on which the signal electrode 14 for polarization is formed at the time of polarization processing is referred to as a polarization pattern surface 111. Then, in the following, as shown in the figure, in the polarization pattern surface 111 of the piezoelectric body 11, the gap (101, 102) separating the A phase region 12a and the B phase region 12b The directions are defined, and the left and right directions are defined as viewed from the rear as shown in the figure.

  As shown in FIG. 2B, the other surface 112 of the piezoelectric body 11 is formed symmetrically with respect to the front-rear direction while including each of the A-phase region 12a and the B-phase region 12b. Two arc-shaped electrodes (hereinafter also referred to as a polarization ground electrode 16) are formed. That is, when viewed from the vertical direction, of the three terminal electrodes 15 disposed in the gap 102 on the rear side of the polarization pattern surface 111, the two terminal electrodes 15 on the left and right sides are the rear end region of the polarization ground electrode 16 and It is overlapping. Hereinafter, the surface on which the polarization ground electrode 16 is formed will be referred to as a polarization ground surface 112.

  As described above, in the single-layer piezoelectric element 10, three types of electrodes, the polarization signal electrode 14, the polarization ground electrode 16, and the terminal electrode 15, are formed at the time of performing the polarization process. When the polarization process is performed, the polarization signal electrode 14 and the polarization ground electrode 16 are used. In the polarization treatment, for example, while the piezoelectric body 11 having the electrode structure shown in FIG. 2 is immersed in silicon oil, the polarization ground electrode 16 is grounded, and the polarization ground electrode 16 and the individual signal electrodes 14 for polarization By applying a strong electric field in a direction according to the polarization polarity of each polarization region 13.

=== First Example ===
As a first embodiment of the present invention, a multilayer piezoelectric element in which two single-layer piezoelectric elements are vertically stacked will be described. And when forming an ultrasonic motor using a lamination type piezoelectric element below, suppose that the upper and lower sides are defined by making the field of the side which contacts a stator into a lower surface.

<Outline of stacked piezoelectric element>
In the multi-layer piezoelectric element according to the first embodiment, the electrode used in the polarization process has a different structure from the electrode to which the drive signal is applied to generate the traveling wave. FIG. 3 is a perspective view of the multi-layer piezoelectric element 1a according to the first embodiment as viewed from the upper rear. The multilayer piezoelectric element 1a is formed by stacking two single-layer piezoelectric elements (10u, 10d) in the vertical direction. As described above, the stator is brought into contact with the lower surface of the laminated piezoelectric element 1a. As is well known, the metallic stator is itself grounded. As a result, the lower surface of the laminated piezoelectric element 1a in contact with the stator is also grounded.

  A C-shaped electrode (hereinafter, also referred to as a ground electrode 21) in which a part of the annular ring is opened is formed on the top surface of the laminated piezoelectric element 1a. The ground electrode 21 has a shape different from that of the polarization signal electrode 14 and the polarization ground electrode 16 shown in FIG. The ground electrode 21 is formed in a region including both the A-phase region 12a and the B-phase region 12b shown in FIG. In addition, three terminal electrodes 15 used at the time of polarization processing remain in a region where the annular ring is opened by the C-shaped ground electrode 21. The ground electrode 21 is grounded by being connected to the stator via an external wiring, and the like, and an external wiring such as a printed wiring board (FPC) is connected to the predetermined terminal electrode 22, and the ground electrode 21 is connected via the wiring. Thus, the drive signal is supplied from the external circuit. Further, on the end face of the upper piezoelectric element 10 u, side electrodes 23 straddling the front and back of the piezoelectric body 11 are formed at positions corresponding to predetermined terminal electrodes 22 to which wiring from the outside is connected.

<Electrode structure of laminated piezoelectric element>
The multilayer piezoelectric element according to the first embodiment has the side electrodes (FIG. 3, reference numeral 23), while the shape and arrangement of the electrodes formed on each single-layer type piezoelectric element, one single-layer type The present invention is characterized in the connection structure of electrodes between the front and back of the piezoelectric element and the connection structure of electrodes between layers of a plurality of single-layer piezoelectric elements. And the short circuit and discharge can be reliably prevented by the characteristics.

  FIG. 4 is a view showing an electrode structure of the multilayer piezoelectric element 1a according to the first embodiment. In FIG. 4, only the electrodes are shown, and the shapes of the electrodes formed on the upper surface and the lower surface of each single-layer piezoelectric element (10a, 10b) when the multilayer piezoelectric element 1a is viewed from the upper rear side. And the arrangement is shown. That is, the electrodes on the lower surface of the single-layer piezoelectric element (10a, 10b) are shown as being transmitted upward.

  In the multilayer piezoelectric element 1a according to the first embodiment, the shapes of the electrodes formed at the time of the polarization process are the back and forth and the left and right between the layers facing the upper and lower single-layer piezoelectric elements (10a, 10b). It is a plane-symmetrical relationship with respect to a plane including each direction. The upper surface 211 of the upper single-layer piezoelectric element (hereinafter also referred to as the upper piezoelectric element 10 u) is a polarization pattern surface 111 at the time of polarization processing. That is, at the time of polarization processing, the lower surface 212 of the upper piezoelectric element 10 u is the polarization ground surface 112.

  However, as shown in FIG. 3, the C-shaped ground electrode 21 is formed on the upper surface 211 of the upper piezoelectric element 10 u. In the laminated piezoelectric element 1a according to the first embodiment, a conductive paste (for example, Doatite (registered trademark: Fujikura Kasei Co., Ltd.)) or the like is applied to the upper surface 211 of the upper piezoelectric element 10u, 14, 14) are connected to form a C-shaped ground electrode 21 which collectively includes the A-phase region 12a and the B-phase region 12b. That is, at the time of polarization processing, the ground electrode 21 is formed on the polarization pattern surface 111 where the polarization signal electrode 14 with the central angle θ2 was formed.

  On the lower surface 212 of the upper piezoelectric element 10 u, two arc-shaped polarization ground electrodes 16 that are grounded at the time of polarization processing are formed. In the laminated piezoelectric element 1a, the two polarization ground electrodes 16 are an electrode to which an A-phase signal is applied (hereinafter also referred to as A-phase signal electrode 24a) and an electrode to which a B-phase signal is applied (hereinafter, B-phase It is also used as a signal electrode 24b). Further, among the three terminal electrodes 15 formed behind the upper surface 211, the left terminal electrode adjacent to the A-phase region 12a (hereinafter also referred to as A-phase terminal electrode 22a) and the right side adjacent to the B-phase region Terminal electrodes (hereinafter also referred to as B-phase terminal electrodes and 22b) are connected to the A-phase terminal electrodes 22a and B-phase terminal electrodes 22b of the lower surface 212 via the side electrodes 23, respectively. Hereinafter, the side electrode 23 connected to the A-phase terminal electrode 22a is referred to as an A-phase side electrode 23a and referred to as a B-phase side electrode 23b, as necessary.

  In the lower piezoelectric element 10 d, the upper surface 213 is the polarized ground surface 112, and the lower surface 214 is the polarized pattern surface 111. Further, the electrodes (16, 14) used in the polarization process remain on the upper surface 213 and the lower surface 214 of the lower piezoelectric element 10d. Then, in the laminated piezoelectric element 1a having the above electrode structure, the A-phase signal electrode 24a and the B-phase signal electrode 24b of the upper piezoelectric element 10u are A via the A-phase side electrode 23a and the B-phase side electrode 23b, respectively. It is connected to phase terminal electrode 22a and B phase terminal electrode 22b.

  Furthermore, the lower surface 212 of the upper piezoelectric element 10 u and the upper surface 213 of the lower piezoelectric element 10 d are bonded, for example, by an epoxy-based adhesive. Therefore, the left and right polarization ground electrodes 16 formed on the upper surface 213 of the lower piezoelectric element 10d are arc-shaped A-phase signal electrodes 24a formed on the lower surface 212 of the upper piezoelectric element 10u. And the B phase signal electrode 24b. As a result, the left and right polarization ground electrodes 16 formed on the upper surface 213 of the lower piezoelectric element 10d become the A-phase signal electrode 24a and the B-phase signal electrode 24b, respectively. Further, the fan-shaped polarization signal electrode 14 formed on the lower surface 214 of the lower piezoelectric element 10d is grounded via a stator in contact with the lower surface 214 of the lower piezoelectric element 10d.

  In the laminated piezoelectric element 1a shown in FIG. 4, the front terminal electrodes (22g, 22g) on the upper surface (211, 213) and the lower surface (212, 214) of the upper piezoelectric element 10u and the lower piezoelectric element 10d are It is connected by the side electrode 23g. The side electrode 23g is an electrode for reliably grounding the ground electrode 21 on the upper surface 211 of the upper piezoelectric element 10u and the polarization signal electrode 14 on the lower surface 214 of the lower piezoelectric element 10d. The lower surface 214 contacts the stator and the front terminal electrode (hereinafter also referred to as the ground terminal electrode 22g) is grounded, whereby the front side electrodes (hereinafter referred to as the ground) in the upper piezoelectric element 10u and the lower piezoelectric element 10d. A ground path is formed from the upper surface 211 of the upper piezoelectric element 10 u to the lower surface 214 of the lower piezoelectric element 10 d via the side electrode 23 g).

  In the multilayer piezoelectric element 1a according to the first embodiment having the above-described electrode structure, the side electrode 23 does not cross the layer between the upper piezoelectric element 10u and the lower piezoelectric element 10d. Therefore, even if the side electrode 23 is formed of a metal paste, there is little possibility of intruding between layers, and a short circuit or a discharge hardly occurs. Furthermore, since the side electrodes 23 may be formed only on the upper piezoelectric element 10 u, they can be formed of baked silver having no fluidity like metal paste. If the side electrode 23 is baked and formed of silver, a short circuit or a discharge can be reliably prevented. In addition, since baked silver has a lower resistance than metal paste, if the side electrode 23 is formed of baked silver, the voltage drop of the drive signal applied through the signal electrode can be reduced, which is a laminated type. It becomes possible to drive the piezoelectric element 1a with a lower voltage.

  The polarization region 13 of the piezoelectric body 11 is destroyed by heat, so the side electrode 23 made of baked silver needs to be formed before the polarization treatment. And in the conventional laminated piezoelectric element, since the side electrode is formed so as to straddle the layers, the side electrode must necessarily be formed after the polarization treatment. That is, in the conventional laminated piezoelectric element, the side electrode can not be baked and formed of silver. On the other hand, in the laminated piezoelectric element 1a according to the first embodiment, the side electrode 23 has a structure without straddling the layers, and the side electrode 23 made of baked silver is used together with the polarization signal electrode 14 and the polarization ground electrode 16. It can be formed at the same time. Further, if the side electrode 23 is formed simultaneously with the signal electrode 14 for polarization and the ground electrode 16 for polarization, the step of applying the metal paste to form the side electrode is not necessary, so the manufacturing cost of the laminated piezoelectric element 1a Can be reduced.

=== Second Example ===
The multilayer piezoelectric element 1a according to the first embodiment is a two-layer type in which two single-layer piezoelectric elements (10a, 10b) are stacked. The multi-layer piezoelectric element 1a according to the first embodiment uses the side electrodes 23 not straddling the layers to drive the A-phase and B-phase signal electrodes (22a, 22b) formed between the layers. It has a basic structure that can be applied. And this basic structure is applicable also to a lamination type piezoelectric element of three or more layers. Therefore, a three-layered laminated piezoelectric element will be described as a second embodiment.

  FIG. 5 shows an electrode structure when the multilayer piezoelectric element 1b according to the second embodiment is viewed from the upper rear. In FIG. 5, the piezoelectric bodies of the single-layer piezoelectric elements (10 u, 10 m, 10 d) are omitted as in FIG. 4, and the lower surfaces (212, 212) of the single-layer piezoelectric elements (10 u, 10 m, 10 d) are omitted. Electrodes 216 and 214) are shown to be transmitted upward. In the following, the lowermost single-layer piezoelectric element 10d may be referred to as a first layer 10d in the case of three single-layer piezoelectric elements (10u, 10m, 10d) constituting the multi-layer piezoelectric element 1b. . Then, the second layer 10 m and the third layer 10 u may be referred to sequentially from the first layer 10 d upward. With respect to the front and back surfaces of each layer (10u, 10m, 10d), regardless of the shape of the electrode, the surface to which the surfaces of A phase region 12a and B phase region 12b are grounded is referred to as ground plane 200g, A phase region 12a The surface to which the drive signal of A phase and B phase is applied to the surface of B phase area 12b is called drive surface 200s.

  Also in the laminated piezoelectric element 1b according to the second embodiment, a stator is disposed on the lower surface 214 of the lowermost first layer 10d. Further, as shown in FIG. 5, the multilayer piezoelectric element 1b according to the second embodiment is located on the upper side from the ground plane 200g of the lower surface 214 of the first layer 10d to the drive surface 200s of the upper surface 211 of the third layer 10u. The surfaces facing each other in the layers (10d-10m, 10m-10u) of each layer are in the order of the driving surface 200s and the ground surface 200g. In the multi-layer piezoelectric element 1b according to the second embodiment, the formation states of the electrodes of the first layer 10d and the second layer 10m are the same as those of the multi-layer piezoelectric element 1a according to the first embodiment. The electrode shape of the single-layer piezoelectric element of the three-layer 10 u is different from any of the first layer 10 d and the second layer 10 m.

  In the third layer 10 u, the lower surface 212 is the polarization pattern surface 111 and the upper surface 211 is the polarization ground surface 112 in the polarization processing. Then, in the state of the laminated piezoelectric element 1b, the lower surface 212 is the ground surface 200g, and the upper surface 211 is the drive surface 200s. In the third layer 10u, the two arc-shaped polarized ground electrodes 16 on the upper surface 211 are used as signal electrodes (24a, 24b) of A phase and B phase, respectively. In addition, polarization signal electrodes 14 are formed in the A-phase region 12a and the B-phase region 12b of the lower surface 212, and the front and rear gaps (101, 102) separating the A-phase region 12a and the B-phase region 12b, respectively. One terminal electrode 15 and three terminal electrodes 15 are formed on the substrate. Of the three terminal electrodes 15 formed in the rear gap 102, the left and right terminal electrodes (22a, 22b) are the A-phase terminal electrode 22a and the B-phase terminal electrode 22b, respectively. . The A-phase terminal electrode 22a and the B-phase terminal electrode 22b are connected to the A-phase signal electrode 24a and the B-phase signal electrode 24b via the A-phase side electrode 23a and the B-phase side electrode 23b, respectively. Furthermore, one ground terminal electrode (22g, 22g) in front of the upper surface 211 and the lower surface 212 is connected via the ground side electrode 23g.

  In the multi-layer piezoelectric element 1b according to the second embodiment, the A-phase signal electrode and the B-phase signal electrode 24b formed on the upper surface 211 of the third layer 10u have the A-phase signal and the B-phase, respectively. When a phase signal is applied, the A phase and B phase drive signals are generated by the A phase side electrode 23a and the B phase side electrode 23b of the third layer 10u, and the A phase terminal electrode 22a and B of the lower surface 212 of the third layer. The voltage is applied to the A-phase terminal electrode 22a and the B-phase terminal electrode 22b on the upper surface 215 of the second layer 10m via the phase terminal electrode 22b.

  Further, the ground electrode 21 of the second layer 10m is grounded by the ground terminal electrode 22g and the ground side electrode 23g in front of the upper surface 211 of the third layer 10u. By grounding the front ground terminal electrode 22g of the third layer, the grounding terminal electrode 22g of the lower surface 212 of the third layer 10u is also grounded via the ground side electrode 23g in front of the third layer 10u. The ground terminal electrode 22g of the lower surface 212 of the third layer 10u is in contact with the ground electrode 21 of the upper surface 215 of the second layer 10m. For the second layer 10m and the first layer 10d, the lower surface 216 and the first layer 10d of the second layer 10m are formed by the same electrode structure and conduction path as the upper piezoelectric element 10u and the lower piezoelectric element 10d in the first embodiment. The upper surface 213 of the first layer 10d is the drive surface 200s, and the lower surface 214 of the first layer 10d is the ground surface 200g. The ground electrode 21 formed on the upper surface 215 of the second layer 10m may be formed on the lower surface 212 of the third layer 10u. In any case, the ground electrode 21 may be formed on any one of the upper and lower single-layer piezoelectric elements (10 u, 10 m) in the layer in which the electrode pattern surfaces (111, 111) face each other in the vertical direction.

  When a plurality of single-layer piezoelectric elements are bonded to produce a multi-layer piezoelectric element, a plurality of single-layer laminated layers are usually stacked to reduce the thickness of the adhesive between the layers as much as possible. The pressure-type piezoelectric element is crimped to push the adhesive between the layers outward. In the laminated piezoelectric element 1b according to the second embodiment, the polarization signal electrode 14 is formed on the upper surface 215 of the second layer 10m and the lower surface 212 of the third layer 10u. Therefore, when the polarization signal electrode 14 is formed of thick film baked silver or the like, the layer between the second layer 10m and the third layer has a large height difference in the vertical direction due to a plurality of thick irregularities along the annular ring. The gaps will line up intermittently in an annular shape. Therefore, at the time of pressure bonding, the second layer 10m and the third layer 10d bend along the asperities, and any single layer type piezoelectric element (10u including the second layer 10m and the third layer 10u) constituting the laminated piezoelectric element 1b , 10m, 10d) may be damaged. Alternatively, tight control of the crimping conditions may occur, which may increase the manufacturing cost. Therefore, in the multilayer piezoelectric element 1b according to the second embodiment having a structure in which the polarization pattern surfaces 111 face each other, at least the electrodes (14, 15) of the polarization pattern surface 111, and further, the electrodes (14, 15) Preferably, the ground electrode 21 formed on the surface layer of the above is a thin film electrode formed using sputtering or the like.

<Modification>
Various modifications can be considered for the multi-layer piezoelectric element 1b according to the second embodiment using three single-layer piezoelectric elements (10 u, 10 m, 10 d). For example, in the multi-layer piezoelectric element 1c shown in FIG. 6, the ground electrode 21 is not formed on the upper surface 215 of the second layer 10m of the multi-layer piezoelectric element 1 b shown in FIG. In the polarization processing at 10 u, the upper surface 211 is the polarization pattern surface 111, and the lower surface 212 is the polarization ground surface 112. Then, in the polarized ground plane 112 of the lower surface 212 of the third layer 10u, both of the A-phase region 12a and the B-phase region 12b are replaced by the two arc ground polarization ground electrodes 16 shown in FIGS. While being included, a C-shaped electrode 17 is formed in which the rear of the annular ring is open. That is, on the lower surface 212 of the third layer 10u, the polarization ground electrode 17 having the same shape as the ground electrode 21 formed on the upper surface 215 of the second layer 10m of the multilayer piezoelectric element 1b shown in FIG. It is done. Further, two arc-shaped electrodes (25a, 25a, 25b) are formed on the upper surface 211 of the third layer 10u by connecting the polarization signal electrodes 14 corresponding to the A phase region 12a and the B phase region 12b by conductive paste or the like. 25b) is formed. The arc-shaped electrode 25a formed in the A-phase region 12a of the upper surface 211 of the third layer 10u becomes an A-phase signal electrode 25a to which an A-phase signal is applied, and is formed in the B-phase region 12b. The electrode 25b becomes a B-phase signal electrode 25b to which a B-phase signal is applied. In the laminated piezoelectric element 1c shown in FIG. 6, both the upper surface 215 of the second layer 10m and the lower surface 212 of the third layer 10u do not become the polarization pattern surface 111, and the lower surface 212 of the third layer 10u is polarized. The contact surface 112 is formed. Since two arc-shaped ground electrodes 16 for polarization including the A-phase region 12a and the B-phase region 12b are formed on the polarized ground plane 112, no large difference in height occurs between layers, and the signal electrode for polarization is generated. Even when the thin film 14 or the polarization ground electrode 16 is not formed as a thin film, the single-layer piezoelectric elements (10u, 10m, 10d) are less likely to be damaged during pressure bonding. In addition, it is not necessary to additionally form the ground electrode 21 on the upper surface 215 of the second layer 10m.

  FIG. 7 is a view showing another modified example of the laminated piezoelectric element 1b according to the second embodiment. The laminated piezoelectric element 1d shown in FIG. 7 has shapes and shapes of electrodes on the upper surface (211, 215, 213) and the lower surface (212, 216, 214) of the first layer 10d, the second layer 10m, and the third layer 10u. The structure is the same as that of the multilayer piezoelectric element 1b according to the second embodiment. However, the ground terminal electrode 22g is not provided on the upper surface 211 of the third layer 10u, and the terminal electrodes 15 of the upper surface 213 and the lower surface 214 of the first layer 10d and the upper surface 215 and the lower surface 216 of the second layer 10m are used as the ground terminal electrode 22g. . The ground terminal electrodes (22g, 22g) on the upper surface (213 and 215) and the lower surface (214 and 216) of the first layer 10d and the second layer 10m are connected to each other via the ground side electrode 23g.

  In any case, in the laminated piezoelectric element provided with three or more single-layer piezoelectric elements, the upper surface and the lower surface of two single-layer piezoelectric elements facing each other between layers are sequentially grounded from the bottom to the top , And may be disposed in the order of the drive surface. Then, one side electrode is formed only on the end face of one single-layer type piezoelectric element, and the terminal electrode and the side electrode form a ground path for the layer from the ground plane or drive plane to the outside and a conduction path for drive signal. It should just be formed.

=== Ultrasonic motor ===
An ultrasonic motor according to an embodiment of the present invention has a structure in which a stator is adhered to the lower surface of the laminated piezoelectric element according to the above-described embodiment of the present invention. An adhesive is layered between the stacked piezoelectric element and the stator. When the adhesive layer (hereinafter also referred to as adhesive layer) has an excessive thickness, it acts as a shock absorbing material, and the transmission efficiency of vibration from the laminated piezoelectric element to the stator decreases. In addition, the adhesive layer may act as a dielectric layer to make the ground potential unstable. However, in order to ensure the adhesive strength between the stator and the laminated piezoelectric element, the adhesive layer needs to have a certain thickness (for example, 5 μm to 10 μm). Therefore, conductive fillers such as metals and carbon materials may be mixed between the layers of the laminated piezoelectric element and the stator.

  Fillers are particles or powders added to adhesives, resins, rubbers, paints, etc. for the purpose of improving strength and functionality, etc., and conductive between the laminate type piezoelectric element and the stator and harder than adhesives. If the filler is interposed, the adhesion strength between the laminated piezoelectric element and the stator is secured, and then the transmission efficiency and the conductivity of the vibration between the laminated piezoelectric element and the stator are improved. The particle diameter of the filler may be appropriately set according to the thickness of the adhesive layer, and in the multilayer piezoelectric elements (10a, 10b) according to the first and second embodiments, the thickness is determined. Is about 5 μm to 10 μm. Therefore, a filler having a particle diameter of about 5 μm to 10 μm may be used as the filler mixed in the adhesive layer.

=== Other Examples ===
In the multilayer piezoelectric element according to the above embodiment, the plurality of single-layer piezoelectric elements are stacked in direct contact with each other. However, when the single-layer piezoelectric elements made of hard ceramic are brought into direct contact with each other and the single-layer piezoelectric elements are largely vibrated, the single-layer piezoelectric elements may be damaged. Therefore, an FPC may be interposed between layers facing the single-layer piezoelectric element in the vertical direction. FIG. 8 shows a laminated piezoelectric element 1e in which an FPC 30 is interposed between layers. A laminated piezoelectric element 1e shown in FIG. 8 is a modification of the first embodiment, and FIG. 8 shows single-layer piezoelectric elements (10 u, 10 v) when the laminated piezoelectric element 1 e is viewed from the upper rear. 10d) and the electrode structure of the FPC 30 are shown.

  The planar shape of the FPC 30 is an annular shape along the outer shape of the single-layer type piezoelectric element (10u, 10d), and the A-phase signal electrode 24a and the B-phase signal formed on the lower surface 212 of the upper piezoelectric element 10u on the upper surface 31 Two wires (33a, 33b) made of a conductor such as copper foil are formed in an arc shape so as to face the electrode 24b. Further, also on the lower surface 32, two wires (not shown) having the same shape when viewed from above are formed at the same position. Then, each of the two arc-shaped wires (33a, 33b) formed on the upper surface 31 is a wire of the same shape formed at the same position on the lower surface 32 through the conductive portion 34 such as a through hole. It is connected. The conductors (33a, 33b) formed on the FPC 30 have the conductors exposed on the surface, and these wirings (33a, 33b) respectively correspond to the lower surface 212 and the lower piezoelectric element 10d of the upper piezoelectric element 10u. The A-phase signal electrodes 24 a and the B-phase signal electrodes 24 b formed on the upper surfaces 213 of the metal layers are connected by metal paste or the like.

  In the multi-layer piezoelectric element 1a according to the first embodiment, A-phase and B-phase drive signals are transmitted through the A-phase signal electrode 24a and the B-phase signal electrode 24b formed on the lower surface 212 of the upper piezoelectric element 10u. The voltage is applied to the A-phase region 12a and the B-phase region 12b of the lower piezoelectric element 10d. Therefore, if the polarization polarity of the polarized area 13 which is at the same position when viewed from above is the same, the lower piezoelectric element 10d is arranged so that the front and back is reversed and the polarized ground plane 112 becomes the upper surface 213. May be

  Further, in the laminated piezoelectric element 1a according to the first embodiment, the ground side electrode 22g is used to ensure that the ground electrode 21 on the upper surface 211 of the upper piezoelectric element 10u is at the ground potential. A ground path is formed from the lower surface 214 to the ground electrode 21 of the upper surface 211 of the upper piezoelectric element 10 u. However, if the C-shaped ground electrode 21 formed on the upper surface 211 of the upper piezoelectric element 10 u is grounded via the external wiring, the ground side electrode 22 g of the upper piezoelectric element 10 u and the lower piezoelectric element 10 d is omitted. You can also

  The polarization pattern surface 111 and the polarization ground surface 112 of the single-layer piezoelectric element (10u, 10m, 10d) constituting each of the laminated piezoelectric elements (1a to 1e) have an arc shape or the like over the entire circumference of the annular ring. Fan-shaped electrodes (14 to 16) were formed. However, among these electrodes (14 to 16), some of the terminal electrodes 15 do not contribute to grounding or conduction with an external circuit at the time of driving. Therefore, the terminal electrodes 15 not used at the time of driving may not be formed.

  Also, with the A phase region 12a and the B phase region 12b on the front and back one surface of each single-layer piezoelectric element (10u, 10m, 10d) as the ground potential, the A phase region 12a and the B phase 12b on the other surface If the A-phase signal and the B-phase signal can be applied separately, the electrodes (14 to 16) on the surface of the single-layer piezoelectric element are removed after the polarization process, and it is necessary for driving. The electrodes may be reformed. Alternatively, it is also conceivable to polarize each polarization region by pressing an electrode corresponding to the shape of each polarization region onto the surface of the piezoelectric material and applying an electric field to the piezoelectric material through the electrode.

  In the first and second embodiments, the electrode structures of the polarization pattern surface 111 and the polarization ground surface 112 are the same in all single-layer piezoelectric elements (10 u, 10 m, 10 d). Therefore, the laminated piezoelectric elements (1a, 1b) according to the first and second embodiments do not need to change the electrode structure for each layer (10u, 10m, 10d), and have a structure that facilitates cost reduction. It can be said that

  In the multi-layer piezoelectric element according to the embodiment of the present invention, with the lower surface of the first layer as the ground surface, the surfaces of the single-layer piezoelectric elements facing each other in the layer facing upward are in order of the drive surface and the ground surface. It should just be arrange | positioned. Then, between the layers where the two single-layer piezoelectric elements face each other at the drive surfaces, an A-phase signal electrode and a B-phase signal electrode may be formed on the surface of the one single-layer piezoelectric element on the interlayer side. Further, in the layer in which the two single-layer piezoelectric elements face each other at the ground plane, the ground electrode may be formed on the surface on the side of the interlayer of one single-layer piezoelectric element. Then, signal terminal electrodes and signal side electrodes are formed on predetermined single-layer piezoelectric elements so that A-phase signals and B-phase signals are applied to the A-phase region and the B-phase region of the drive surface of each single-layer piezoelectric element. It is sufficient that the conduction path of the drive signal be secured from the drive surface between the layers to the upper surface of the uppermost single-layer piezoelectric element. Further, a ground electrode is formed on a predetermined single-layer piezoelectric element so that the A-phase region and the B-phase region of the ground surface of each single-layer piezoelectric element are grounded. A ground path may be secured to the upper surface of the layered piezoelectric element or the lower surface of the first layer. Therefore, the multi-layer piezoelectric element according to the embodiment of the present invention may be configured of four or more single-layer type piezoelectric elements.

1a to 1e stacked piezoelectric element, 10 u, 10 m, 10 d single layer type piezoelectric element,
11 piezoelectric body 12a A phase area 12b B phase area 13 polarization area
14 signal electrodes for polarization, 15, 22, 22a, 22b, 22g terminal electrodes,
16, 17 polarized ground electrode, 21 ground electrode,
23, 23a, 23b, 23g side electrodes, 24a, 25a A phase signal electrodes,
24b, 25b B phase signal electrode, 30 FPC, 33a, 33b FPC wiring,
34 FPC conductive part, 111 polarization pattern surface, 112 polarization ground surface,
200s drive surface, 200g ground surface

Claims (8)

A laminated piezoelectric element disposed in a state in which a stator of an ultrasonic motor is in contact with the lower side thereof,
A single layer type piezoelectric element for one layer consisting of one flat plate-like piezoelectric material is laminated by n layers in the vertical direction, where n is an integer of 2 or more,
In the single-layer type piezoelectric element, the A-phase region and the B-phase region to which the respective A-phase and B-phase drive signals whose phases are shifted by 90 ° are applied to the piezoelectric body in the vertical direction are outside the predetermined range. Arranged in an arc along an annular ring having a diameter and an inner diameter,
The one direction orthogonal to the vertical direction is the front and back direction, and the direction orthogonal to the vertical direction and the front and back direction is the horizontal direction.
The A-phase region and the B-phase region are divided and arranged in a region of a central angle θ1 so as to be symmetrical with respect to a straight line in the front-rear direction which bisects the surface of the annular ring.
A plurality of fan-shaped polarization regions divided at a predetermined central angle θ2 along the annular ring are disposed in the A-phase region and the B-phase region,
The polarization polarity of the polarization region is symmetrical with respect to a straight line in the front-rear direction, and in the A phase region and the B phase region, polarization polarities of adjacent polarization regions are opposite to each other,
In the single-layer piezoelectric element of each layer, polarization regions of the same polarization polarity are arranged at the same position when viewed from above,
One of the front and back surfaces of the single-layer piezoelectric element is a ground surface to which the A phase region and the B phase region are grounded, and the other surface is an A phase in the A phase region and the B phase region. Drive surface to which a signal and a B-phase signal are applied,
The lowermost single-layer piezoelectric element is a first layer, the uppermost single-layer piezoelectric element is an n-th layer, and k is a natural number.
The upper surface of the 2k-1 layer and the lower surface of the 2k layer are the drive surface, and the upper surface of the 2k layer and the lower surface of the 2k + 1 layer are the ground surface,
One of the drive surfaces of two single-layer piezoelectric elements in which the drive surfaces face each other in the vertical direction, and the upper surface of the n-th layer when n = 2k includes the A-phase region, An arc-shaped A-phase signal electrode along the arc, and an arc-shaped B-phase signal electrode along the ring including the B-phase region,
Before and after the A-phase region and the B-phase region on one of the ground planes of the two single-layer piezoelectric elements facing each other in the vertical direction and the top surface of the nth layer when n = 2k + 1 A continuous C-shaped ground electrode is formed along the circular ring leaving one gap,
In the case of n ≧ 3, one of the drive surfaces of the two single-layer piezoelectric elements whose drive surfaces face each other in the vertical direction, and the upper surface of the nth layer and the lower surface of the first layer when n = 2k + 1. On the other hand, fan-like grounding terminal electrodes are formed in the other front and rear gaps separating the A phase region and the B phase region,
In each layer other than the first layer, an A-phase terminal electrode and a B-phase terminal electrode are formed in one of the front and back gaps separating the A-phase region and the B-phase region on the ground plane. An A-phase side electrode and a B-phase side electrode for connecting the end faces of the A-phase terminal electrode, the A-phase terminal electrode on the drive surface and the electrodes formed at positions facing the B-phase terminal electrode respectively;
The n-th A-phase signal electrode and the B-phase signal electrode when n = 2 k, or the n-th phase A-phase terminal electrode and the B-phase terminal electrode when n = 2 k + 1, and the first The A phase region of the drive surface of the first to nth layers and the electrodes formed in each of the B phase regions are connected via the A phase side electrode and the B phase side electrode,
In the case of n 単 層 3, in the single-layer piezoelectric element in which the ground terminal electrode is formed on the drive surface, the ground terminal electrode is separated from the A phase region and the B phase region on the ground surface. A side electrode for grounding is formed to connect the end face to the electrode formed in the other front and rear gap, and is formed in the other front and back region separating the A phase region and the B phase region in the ground plane of each layer. Connected to the active electrode via the ground terminal,
A laminated piezoelectric element for an ultrasonic motor, characterized in that In the laminated piezoelectric element according to claim 1,
In the single-layer piezoelectric element, one of the front and back surfaces is a polarization pattern surface in which a signal electrode for polarization is formed on each surface of the plurality of polarization regions, and the other surface includes the A phase region. And a polarization contact in which an arc-shaped polarization ground electrode for A phase along the annular ring and an arc-shaped polarization ground electrode for B phase along the annular ring including the B phase region are formed. On the ground,
The A-phase signal electrode and the B-phase signal electrode are a polarization ground electrode for the A-phase and a polarization ground electrode for the B-phase, which are formed on the polarization ground plane,
The ground electrode is formed by connecting the signal electrode for polarization formed on the polarization drive surface in the C shape by a conductor.
A laminated piezoelectric element for an ultrasonic motor, characterized in that   3. The multilayer piezoelectric element according to claim 2, wherein in the two single-layer piezoelectric elements wherein n ≧ 3 and in which the polarization pattern surfaces face each other in the vertical direction, the polarization signal electrode is formed of a thin film. A multilayer piezoelectric element for an ultrasonic motor, wherein the A phase signal electrode and the B phase signal electrode of thin film are formed on the surface layer of one polarization pattern surface of the two single layer type piezoelectric elements. In the laminated piezoelectric element according to claim 1,
n ≧ 3 and
A first single-layer piezoelectric element and a second single-layer piezoelectric element,
In the first single-layer piezoelectric element, one of the front and back surfaces is a polarization pattern surface in which a polarization signal electrode is formed on each surface of the plurality of polarization regions, and the other surface is an A-phase region. An arc-shaped polarization ground electrode for A phase along the ring while including it, and a polarization ground electrode for polarization B for the B phase along the ring while including the B phase region are formed Polarized ground plane,
In the second single-layer piezoelectric element, one of the front and back surfaces is a polarization pattern surface in which a polarization signal electrode is formed on each surface of the plurality of polarization regions, and the other surface is the A phase region A polarized ground surface on which a C-shaped polarization ground electrode continuous in an arc shape is formed along the annular ring, leaving one of the front and back gaps separating the B phase region,
The first layer is the first single-layer piezoelectric element,
When k ≧ 2, the 2k-1 layer is the second single-layer piezoelectric element, and the 2k layer is the first single-layer piezoelectric element.
When the uppermost surface which is the upper surface of the nth layer is the ground plane, the polarization signal electrode on the uppermost surface is connected by a conductor and formed on the C-shaped ground electrode,
When the uppermost surface is the drive surface, the predetermined polarization signal electrode on the uppermost surface is connected by a conductor, and the A-phase signal electrode and the B-phase signal electrode are formed.
A laminated piezoelectric element for an ultrasonic motor, characterized in that   The multilayer piezoelectric element for an ultrasonic motor according to any one of claims 2 to 4, wherein the side electrode is baked silver formed by baking a silver paste. In the laminated piezoelectric element according to any one of claims 1 to 5,
A flexible wiring board is disposed between the layers,
In an interlayer in which two single-layer piezoelectric elements face each other on the drive surface, two arcs are formed on the front and back sides of the flexible wiring board so as to face each of the A phase region and the B phase region. And the respective arc-shaped wiring patterns are drawn out of the layers,
In a layer in which two single-layer piezoelectric elements face each other at the ground plane, a C-shape in which a rear gap separating the A-phase region and the B-phase region is opened on both the front and back sides of the flexible wiring board And a portion of the wiring pattern is drawn out of the layer,
The two arc-shaped wiring patterns formed on the front surface and the back surface of the flexible wiring board, and the C-shaped wiring pattern are connected by a wiring member.
A laminated piezoelectric element for an ultrasonic motor, characterized in that   An ultrasonic motor characterized in that a stator is adhered to the lower surface of the laminated piezoelectric element according to any one of claims 1 to 6.   The ultrasonic motor according to claim 7, wherein the laminated piezoelectric element and the stator are bonded by an adhesive to which a filler having conductivity is added.

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