WO2020152905A1

WO2020152905A1 - Stacked piezoelectric element and piezoelectric actuator

Info

Publication number: WO2020152905A1
Application number: PCT/JP2019/036499
Authority: WO
Inventors: 哲哉荒澤; 孝一新美; 尚彦内田
Original assignee: 株式会社フコク
Priority date: 2019-01-21
Filing date: 2019-09-18
Publication date: 2020-07-30
Also published as: JP2020119933A

Abstract

Provided is a stacked piezoelectric element that is capable of accurately and efficiently operating a target.　The stacked piezoelectric element 100 comprises a stacked structure 50 in which a plurality of piezoelectric body layers have been stacked in a stacking direction. An expansion-contraction piezoelectric element 10 comprises a first piezoelectric body layer 11 and an expansion-contraction electrode pair 19 sandwiching the first piezoelectric body layer 11, and expands and contracts in the lengthwise direction of the first piezoelectric body layer via signals input to the expansion-contraction electrode pair 19. A flexural piezoelectric element 20 comprises a second piezoelectric body layer 21 and a flexural electrode pair 29 sandwiching the second piezoelectric body layer 21, and flexes in the widthwise direction of the second piezoelectric body layer via signals input to the flexural electrode pair 29. The expansion-contraction piezoelectric element 10 is disposed so as to include a central position in the stacking direction of the stacked structure 50.

Description

Multilayer piezoelectric element and piezoelectric actuator

The present invention relates to a laminated piezoelectric element and a piezoelectric actuator.

A piezoelectric actuator is a device that converts electrical energy into mechanical energy. For example, it is possible to rotate the rotating body or move the moving body by electrically driving the piezoelectric actuator. For example, the piezoelectric actuator can be operated by applying an electric signal to a piezoelectric element included in the piezoelectric actuator to cause it to vibrate and transmitting the vibration to a rotating body or a moving body via an output member.

Motors that use piezoelectric actuators are being considered, and they are characterized by low speed, high torque, and excellent quietness. For example, it is used as a drive source for a mechanism that requires precise positioning, such as a focus operation of a camera or a microscope.

Although the structure of the piezoelectric actuator is diverse, when a piezoelectric element is used as the electromechanical conversion element, a laminated piezoelectric element in which a plurality of relatively thin piezoelectric elements are laminated may be used. When the laminated piezoelectric element is used, an equivalent amount of displacement can be obtained at a lower voltage as compared with a piezoelectric element using a non-laminated piezoelectric body having the same thickness.

For example, in Patent Document 1, by laminating a plurality of layers of piezoelectric elements and operating these piezoelectric elements, the laminate is bent and expanded and contracted, and an elliptic motion is generated in a driver element for extracting an output. Piezoelectric elements and ultrasonic actuators are disclosed.

International Publication No. 2007/091443

However, in the laminated piezoelectric element described in Patent Document 1, the laminated piezoelectric element is provided with a common electrode for bending drive and extension/contraction drive to perform expansion/contraction and bending operations. Therefore, with the ultrasonic actuator described in Patent Document 1, it is difficult to change the trajectory of the driver element that makes an elliptic motion even if the input signal is adjusted. In other words, in the ultrasonic actuator described in Patent Document 1, even if the input signal is adjusted, the locus of the driver element that makes an elliptic motion is expanded or reduced while maintaining a similar shape.

Originally, a piezoelectric actuator is required to move a rotating body or a moving body to be operated at an arbitrary operation length, an arbitrary speed, and an arbitrary acceleration. When the target is operated by the piezoelectric actuator, the output extraction member of the piezoelectric actuator needs a period of contact with the target and a period of separation thereof. Then, the target is operated by moving the target in the target direction during the contact period.

Here, if you want to operate the target of motion with a small motion length or slow speed, you can reduce the amount of moving the target in the target direction during the period in which the output extraction member contacts the target. However, even in this case, it is necessary to secure a sufficient period for the output take-out member to be in contact with the target, a period for separating the target, and a distance for separating the target.

In the ultrasonic actuator described in Patent Document 1, when it is desired to operate an object to be operated with a small operation length and a slow speed, the amount of movement of the object in the target direction during the period in which the driver contacts the object is reduced. , The trajectory of the elliptical moving driver shrinks while maintaining a similar shape. Therefore, in this case, there is a concern that the period during which the driver element is separated from the target and the distance that the driver element is separated are reduced. For example, if there is no period in which the driver is separated from the target, the target will move in the direction opposite to the target during the period in which the driver contacts the target, and the efficiency of the operation for input will deteriorate. Not only that, it becomes difficult to carry out an accurate operation.

One of the problems relating to the present invention is to provide a laminated piezoelectric element and a piezoelectric actuator capable of operating a target accurately and efficiently.

One aspect of the laminated piezoelectric element according to the present invention is
A flat piezoelectric layer having a longitudinal direction and a lateral direction in a plan view includes a laminated structure in which a plurality of layers are laminated in the laminating direction,
The laminated structure is
A first piezoelectric layer that is one of the plurality of piezoelectric layers; and a pair of expansion/contraction electrodes that sandwich the first piezoelectric layer, and the first piezoelectric body is formed by inputting a signal to the pair of expansion/contraction electrodes. A piezoelectric element for expansion and contraction in the longitudinal direction of the layer,
A second piezoelectric body layer, which is one of the plurality of piezoelectric body layers, and a bending electrode pair that sandwiches the second piezoelectric body layer, and the second piezoelectric body is formed by inputting a signal to the bending electrode pair. A bending piezoelectric element that bends in the lateral direction of the layer,
Including
The expansion/contraction piezoelectric element is arranged so as to include a central position of the laminated structure in the laminating direction.

In the aspect of the laminated piezoelectric element,
The laminated structure is
A wiring layer formed on two side surfaces parallel to the longitudinal direction,
The wiring layer may be formed at a position corresponding to a node in flexural vibration when the laminated piezoelectric element operates.

In any of the above-mentioned laminated piezoelectric elements,
The bending electrode pair,
On one surface of the second piezoelectric layer, four split electrodes arranged in each of four regions divided into two in the longitudinal direction and the lateral direction of the second piezoelectric layer,
A first electrode for bending, which includes a connection wiring for connecting a pair of divided electrodes arranged diagonally among the four divided electrodes,
A second bending electrode disposed on the other surface of the second piezoelectric layer and facing the first bending electrode with the second piezoelectric layer interposed therebetween;
The second bending electrode may include at least a non-overlapping region that does not overlap the connection wiring when the bending piezoelectric element is viewed in the stacking direction of the stacked structure.

In the aspect of the laminated piezoelectric element,
The bending second electrode is located at a position corresponding to a space between the divided electrodes facing each other in the longitudinal direction or the lateral direction of the second piezoelectric layer among the plurality of divided electrodes forming the bending first electrode. It may have voids.

In any of the above-mentioned laminated piezoelectric elements,
The elastic electrode pair,
Formed on the surface of the first piezoelectric layer so as to extend in the longitudinal direction of the first piezoelectric layer;
A constricted portion having a small width of the electrode in the lateral direction may be provided between both ends and a central portion in the longitudinal direction of the first piezoelectric layer.

In any of the above-mentioned laminated piezoelectric elements,
The laminated structure, on the surface of one end side in the stacking direction, is provided with an expansion input terminal connected to the expansion electrode pair, and a bending input terminal connected to the bending electrode pair,
The expansion/contraction input terminal and the bending input terminal may be formed at positions corresponding to nodes in expansion/contraction vibration or bending vibration when the multilayer piezoelectric element operates.

One aspect of the piezoelectric actuator according to the present invention is
A laminated piezoelectric element according to any one of claims 1 to 6,
An output extraction member fixed to the laminated piezoelectric element,
Equipped with.

In the laminated piezoelectric element and the piezoelectric actuator according to the present invention, the bending vibration and the stretching vibration can be individually set to realize the optimum elliptic motion, so that the operation target can be moved accurately and efficiently. ..

FIG. 1 is a perspective view schematically showing a laminated piezoelectric element according to an embodiment. FIG. 2 is a schematic diagram of the laminated piezoelectric element according to the embodiment. FIG. 3 is a schematic diagram showing an example of the electrode pattern of the expansion/contraction electrode according to the embodiment. FIG. 4 is a schematic diagram showing an example of the electrode pattern of the expansion/contraction electrode according to the embodiment. FIG. 5: is a schematic diagram which shows an example of the electrode pattern of the electrode for bending which concerns on embodiment. FIG. 6 is a schematic diagram showing an example of the electrode pattern of the bending electrode according to the embodiment. FIG. 7 is a schematic diagram showing an example of the electrode pattern of the bending electrode according to the embodiment. FIG. 8 is a schematic view showing the shape of bending deformation of the laminated piezoelectric element. FIG. 9 is a schematic diagram showing the shape of expansion and contraction of the laminated piezoelectric element. FIG. 10 is a schematic view showing the piezoelectric actuator according to the embodiment.

Some embodiments of the present invention will be described below. The embodiment described below describes an example of the present invention. The present invention is not limited to the following embodiments, and includes various modifications that are carried out without changing the gist of the present invention. Note that not all the configurations described below are essential configurations of the present invention.

1. Multilayer Piezoelectric Element First, an outline of a multilayer piezoelectric element 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view schematically showing a laminated piezoelectric element 100 according to the embodiment. In FIG. 1, the scale and relative size of each member are not necessarily accurate for convenience of explanation.

The laminated piezoelectric element 100 of the present embodiment includes a laminated structure 50 in which a plurality of flat plate-shaped piezoelectric layers having a longitudinal direction and a lateral direction in a plan view are laminated in the laminating direction. The laminated structure 50 includes the expansion/contraction piezoelectric element 10 and the bending piezoelectric element 20, and the expansion/contraction piezoelectric element 10 includes the center position in the stacking direction of the laminated structure 50. The center position will be described later with reference to FIG.

In this specification, the direction in which the piezoelectric layers are stacked may be referred to as the “stacking direction” and is shown as the Z axis in each figure. Further, the plan view refers to an image projected by a virtual ray parallel to the stacking direction.

Also, having a longitudinal direction means having a longitudinal direction. The longitudinal direction means, for example, a direction along the long side in the case of a rectangle, and a direction along the major axis in the case of an ellipse. The longitudinal direction is shown as the Y-axis in each figure. On the other hand, the short-side direction refers to the direction along the short side in the case of a rectangle, and the direction along the short diameter in the case of an ellipse. The lateral direction is shown as the X-axis in each figure.

The laminated piezoelectric element 100 includes a laminated structure 50 and one side of a surface 110 of the laminated structure 50 that is orthogonal to the laminating direction (that is, a surface on one end side of the laminated structure), an expansion input terminal 60, and a bending input terminal 60. And an input terminal 70. Further, the laminated piezoelectric element 100 includes the wiring layer 80 formed on the two

side surfaces

112 and 113 parallel to the longitudinal direction of the laminated structure 50. The expansion input terminal 60 and the bending input terminal 70 are both electrically connected to the corresponding wiring layer 80.

The laminated structure 50 has a structure in which a plurality of piezoelectric layers are stacked in the stacking direction, fired, and sintered. Therefore, in some cases, the boundaries of layers do not appear clearly on the side surfaces 112 and 113 parallel to the stacking direction of the stacked structure 50. In this case, each piezoelectric layer can be confirmed by microscopic observation or cross-sectional observation. In addition, although each electrode does not appear on the side surfaces 112 and 113 of the laminated structure 50, in the range depicted in FIG. 1, each electrode has an end inside the side surfaces 112 and 113 of the laminated structure 50. Because it has.

1.1. Details of Multilayer Piezoelectric Element Next, details of the multilayer piezoelectric element 100 will be described with reference to FIG. FIG. 2 is a schematic diagram of the laminated piezoelectric element 100 according to the embodiment. On the left side of FIG. 2, a vertical cross-section of the laminated structure of the laminated piezoelectric element 100 is schematically drawn, and on the right side of FIG. 2, each electrode pattern in plan view of the laminated piezoelectric element 100 is schematically drawn. There is.

The laminated piezoelectric element 100 has a plurality of, for example, 12 piezoelectric layers in the laminated structure 50. The laminated structure 50 includes four first piezoelectric layers 11 and four second piezoelectric layers 21.

The first piezoelectric layer 11 is sandwiched by the expansion/contraction electrode pair 19 to form the expansion/contraction piezoelectric element 10, and expands/contracts in the longitudinal direction by inputting a signal to the expansion/contraction electrode pair. Further, the laminated structure 50 includes four layers of the piezoelectric element 10 for expansion and contraction.

The second piezoelectric layer 21 is sandwiched by the bending electrode pair 29 to form the bending piezoelectric element 20, and is bent in the lateral direction by inputting a signal to the bending electrode pair. Further, the laminated structure 50 includes four layers of the bending piezoelectric element 20.

One electrode of the expansion/contraction electrode pair 19 is common to the adjacent expansion/contraction piezoelectric elements 10, and one electrode of the bending electrode pair 29 is common to the adjacent bending piezoelectric element 20. Has become.

On the other hand, of the 12 piezoelectric layers of the laminated structure 50, the piezoelectric layer sandwiched between one electrode of the expansion/contraction electrode pair 19 and one electrode of the bending electrode pair 29 functions as a non-polarization layer. This is the non-polarizing piezoelectric layer 40. Further, among the 12 piezoelectric layers, the piezoelectric layers having the one electrode of the expansion/contraction electrode pair 19 or the one electrode of the bending electrode pair 29 on only one side are provided at both ends of the laminated structure 50 in the laminating direction. The surface piezoelectric layer 30 is arranged. As described above, the laminated structure 50 includes the two layers of the non-polarizing piezoelectric layer 40 and the two layers of the surface piezoelectric layer 30. In the laminated structure 50, the non-polarizing piezoelectric layer 40 is arranged between the expansion piezoelectric element 10 and the bending piezoelectric element 20, and the surface piezoelectric layers 30 are provided at both ends of the laminated structure 50 in the laminating direction. It is arranged.

It is preferable that no voltage be applied to the non-polarizing piezoelectric layer 40, and the non-polarizing piezoelectric layer 40 is grounded in the expansion/contraction electrode pair 19 and grounded in the bending electrode pair 29. It is preferably sandwiched between electrodes. This is because in the absence of the non-polarizing piezoelectric layer 40, there is a piezoelectric layer in which a sufficient polarization region cannot be obtained even if a voltage for polarizing the piezoelectric layer is applied, resulting in a large power consumption. This is because it will end up. To avoid this, the power consumption is suppressed by forming the non-polarizing piezoelectric layer 40.

In the illustrated example, the expansion/contraction electrode pair 19 is composed of an electrode pattern C and an electrode pattern D. The bending electrode pair 29 includes an electrode pattern B and an electrode pattern E. In this case, the electrode patterns D and E are preferably ground electrodes. Each electrode pattern will be described later.

Moreover, in the laminated piezoelectric element 100, the expansion piezoelectric element 10 and the bending piezoelectric element 20 have the same contour in plan view. Then, in the laminated structure 50, the contours of the piezoelectric element 10 for expansion and contraction and the contours of the piezoelectric element 20 for bending overlap in a plan view.

In the laminated piezoelectric element 100, the four piezoelectric elements 10 for expansion and contraction are arranged on the side closer to the central position G in the laminating direction of the laminated structure 50, and the bending piezoelectric element 20 is arranged on the side farther from the central position G for the central position G. Two pieces are arranged symmetrically with respect to.

In the laminated piezoelectric element 100, the center position G of the laminated structure 50 in the laminating direction is included in the two elastic piezoelectric elements 10 inside the four elastic piezoelectric elements 10. More specifically, in the laminated piezoelectric element 100, the center position G of the laminated structure 50 in the laminating direction is an electrode common to the two elastic piezoelectric elements 10 inside the four elastic piezoelectric elements 10. Included in pattern D.

The laminated structure 50 is a continuous body made of sintered ceramics. Therefore, the expansion and contraction of the laminated structure 50 starts from the center position G of the laminated structure 50 and expands and contracts in the longitudinal direction of the laminated structure 50.

The expansion/contraction piezoelectric element 10 is arranged so as to include the central position G in the stacking direction of the laminated structure 50, so that when the laminated piezoelectric element 100 is driven, the origin of the expansion/contraction operation (stretching vibration) is the laminated structure. It can be brought close to the center position G of the body 50. As a result, since it is possible to expand and contract in the longitudinal direction of the laminated structure 50 with the vicinity of the central position G as the starting point, it is possible to improve the efficiency of stretching vibration. The center position G of the laminated structure 50 is, for example, the center of gravity of the laminated structure 50.

1.2. Electrode Patterns of Stretching Piezoelectric Element and Bending Piezoelectric Element FIG. 3 is a schematic diagram showing one electrode pattern D of the stretching electrode pair 19. FIG. 4 is a schematic diagram showing the other electrode pattern C of the expansion/contraction electrode pair 19. FIG. 5 is a schematic diagram showing one electrode pattern B of the bending electrode pair 29. FIG. 6 is a schematic diagram showing the other electrode pattern E of the bending electrode pair 29.

FIG. 3 shows one electrode pattern D of the expansion/contraction electrode pair 19 formed on the first piezoelectric layer 11. Further, FIG. 4 shows one electrode pattern C of the expansion/contraction electrode pair 19 formed on the first piezoelectric layer 11.

The electrodes of the electrode pattern D shown in FIG. 3 and the electrodes of the electrode pattern C shown in FIG. 4 can form a stretchable electrode pair 19. That is, the expansion/contraction piezoelectric element 10 is formed by sandwiching the first piezoelectric layer 11 between the electrode of the electrode pattern D and the electrode of the electrode pattern C.

The electrode patterns D and C have the same shape in plan view except for the lead-out portion 15 when the first piezoelectric layer 11 is sandwiched between the electrode patterns D and C. The lead-out portion 15 extends to the lateral ends (side surfaces 112 and 113) of the first piezoelectric layer 11 so as to be electrically connected to the wiring layer 80.

Thus, the electrode pattern D and the electrode pattern C have two lead portions 15 in total, and each of them can be electrically connected to the wiring layer 80 at different positions on the side surfaces 112 and 113 of the laminated structure 50. ing.

Since the electrode of the electrode pattern D and the electrode of the electrode pattern C have the same shape with the first piezoelectric layer 11 interposed therebetween except for the lead-out portion 15, they do not participate in the driving of the first piezoelectric layer 11. Since the polarization region can be reduced, it is possible to suppress waste of electric power and heat generation during driving. This is because when a region of the first piezoelectric layer 11 that is not involved in driving is polarized, a current is generated in that region during driving. Further, by making the electrode area to the minimum necessary, the factors that hinder vibration can be reduced.

The planar shapes of the electrode pattern D and the electrode pattern C are arbitrary, but in the illustrated example, the electrode pattern D and the electrode pattern C extend in the longitudinal direction on the surface of the first piezoelectric layer 11. ing. Further, in the illustrated example, the shapes of the electrode pattern D and the electrode pattern C have a constricted portion 18 having a small width in the lateral direction between the longitudinal end portions 16 and the central portion 17. ..

By the way, it has been known that the expansion and contraction of the piezoelectric element 10 for expansion and contraction is largely contributed by the expansion and contraction near the center of the first piezoelectric layer 11. Therefore, the area of the electrodes of the electrode pattern D and the electrode pattern C should be designed to be larger in the central portion 17 and smaller toward the both end portions 16 so that the expansion/contraction operation is sufficiently performed and the power consumption is reduced. It is preferable from the viewpoint. However, when a load for compressing the expansion/contraction piezoelectric element 10 in the longitudinal direction is applied, as in the case where the laminated piezoelectric element 100 is used as a piezoelectric actuator and abutted against and pressed against an object to be driven, the load is further increased. By performing the expansion/contraction operation at a position close to the applied position, the expansion/contraction operation can be made more efficient. From this point of view, as shown in the figure, it is more preferable to provide the electrode pattern D and the electrode pattern C with a constricted portion 18 having a small width in the lateral direction between the longitudinal end portions 16 and the central portion 17. preferable.

FIG. 5 shows one electrode pattern B of the bending electrode pair 29 formed on the second piezoelectric layer 21. Further, FIG. 6 shows one electrode pattern E of the bending electrode pair 29 formed on the second piezoelectric layer 21.

The electrodes of the electrode pattern B shown in FIG. 4 and the electrodes of the electrode pattern E shown in FIG. 5 can form a bending electrode pair 29. That is, the bending piezoelectric element 20 is formed by sandwiching the second piezoelectric layer 21 by the electrode of the electrode pattern B and the electrode of the electrode pattern E.

The electrode pattern B includes four divided

electrodes

26a, 26b, 26c, 26d arranged in each of four regions formed by dividing the surface of the second piezoelectric layer 21 into two in the longitudinal direction and the lateral direction. A pair of divided

electrodes

26a, 26c, 26d, which are diagonally arranged, and a connection wiring 27 for connecting a pair of divided

electrodes

26a, 26d.

In addition, the electrode pattern B is the end of the second piezoelectric layer 21 in the lateral direction from each of the two divided

electrodes

26b, 26c which are not connected by the connection wiring 27 among the four divided

electrodes

26a, 26b, 26c, 26d. A total of three lead portions 25 extending up to and one lead portion 25 extending from one divided electrode 26a connected by the connection wiring 27 to the short-side end of the second piezoelectric layer 21. It has two drawers 25.

On the other hand, the electrode pattern E has a shape that includes the four divided

electrodes

26a, 26b, 26c, and 26d of the electrode pattern B when the electrode pattern B is stacked except the second piezoelectric layer 21. .. Therefore, polarized regions corresponding to the four divided

electrodes

26a, 26b, 26c, 26d can be obtained.

In addition, the electrode pattern E is a lead-out that extends to the end in the lateral direction at a position different from the three lead-out portions 25 of the electrode pattern B when the electrode pattern B is stacked except for the second piezoelectric layer 21. It has a section 25.

Further, the electrode pattern E has an opening 27a at a position corresponding to the connection wiring 27 of the electrode pattern B when the electrode pattern B is stacked except for the second piezoelectric layer 21. No electrode is present in the opening 27a. It can be said that the opening 27a is a non-overlapping region that does not overlap with the connection wiring 27.

Since the electrode of the electrode pattern E has the opening 27a and does not overlap with the connection wiring 27, the region of the second piezoelectric layer 21 that is not involved in driving is not polarized, and waste of power and heat generation during driving are suppressed. be able to.

In this way, the electrode pattern B and the electrode pattern E have a total of four lead portions 25, and each can be electrically connected to the wiring layer 80 at different positions on the side surfaces 112 and 113 of the laminated structure 50.

FIG. 7 is a schematic diagram showing an electrode pattern F which is a modified example of the electrode pattern E. In the above-mentioned electrode pattern E, when the electrode pattern B is overlapped except for the second piezoelectric layer 21, the electrodes also exist in the gaps between the divided

electrodes

26a, 26b, 26c and 26d of the electrode pattern B. It was That is, the polarization region that is not involved in driving the second piezoelectric layer 21 is formed in the gap between the divided

electrodes

26a, 26b, 26c, and 26d.

In the electrode pattern F shown in FIG. 7, slit-shaped openings 27b are formed at positions corresponding to the gaps between the divided

electrodes

26a, 26b, 26c, 26d. That is, the electrode pattern F has a void at a position corresponding to the void between the divided electrodes facing each other in the longitudinal direction or the lateral direction of the plurality of divided electrodes of the electrode pattern B.

By using the shape of the electrode pattern F shown in FIG. 7, the region of the second piezoelectric layer 21 that is not involved in driving is not polarized, so that it is possible to further suppress power waste and heat generation during driving. Further, since the laminated piezoelectric element 100 of the present embodiment includes the bending piezoelectric element 20 having four layers, the effect of providing the

openings

27a and 27b like the electrode patterns E and F is remarkable. appear. The effect becomes more remarkable as the number of the bending piezoelectric elements 20 increases.

1.3. Operation of Multilayer Piezoelectric Element FIG. 8 is a schematic diagram in which bending vibration of the multilayer piezoelectric element 100 is simulated and a deformation state is viewed in plan. FIG. 9 is a schematic diagram in which the expansion and contraction vibration of the laminated piezoelectric element 100 is simulated and the deformation is viewed in plan. In FIGS. 8 and 9, the deformation amount is enlarged and shown in order to visualize the deformation. Further, illustration of each terminal is omitted in FIGS. 8 and 9.

As shown in FIG. 8, when the laminated piezoelectric element 100 flexurally vibrates at a frequency near the resonance frequency, three regions with less displacement occur. In addition, as shown in FIG. 9, when the laminated piezoelectric element 100 expands and contracts at a frequency near the resonance frequency, one region having a small displacement is generated. These areas with less displacement are called "nodes". In FIG. 8 and FIG. 9, the positions of the nodes are shown surrounded by a chain line.

1.4. Wiring Layer, Terminal, and Arrangement thereof As shown in FIG. 2, the wiring layer 80 is electrically connected to the expansion electrode pair 19 and the bending electrode pair 29, respectively. The wiring layer 80 connected to the expansion/contraction electrode pair 19 is electrically connected to the expansion/contraction input terminal 60. The wiring layer 80 connected to the bending electrode pair 29 is electrically connected to the bending input terminal 70.

As shown in FIG. 8, the wiring layer 80 is formed on the side surfaces 112 and 113 of the laminated structure 50 parallel to the longitudinal direction, and corresponds to any node in bending vibration when the laminated piezoelectric element 100 operates. It is preferably formed in position.

Further, the expansion/contraction input terminal 60 and the bending input terminal 70 are preferably arranged at positions corresponding to any nodes in the expansion/contraction vibration and the bending vibration when the laminated piezoelectric element 100 operates.

In this case, the expansion/contraction input terminal 60 is a node in expansion/contraction motion and bending vibration when the multilayer piezoelectric element 100 operates, and may be arranged at a position corresponding to a node generated in the central region in the longitudinal direction. More preferable.

The flexural displacement is small in the nodes in flexural vibration when the multilayer piezoelectric element 100 operates, but the flexural displacement is large in the regions other than the nodes. Since all of the wiring layer 80, the expansion/contraction input terminal 60, and the bending input terminal 70 adversely affect the stretching vibration and the bending vibration, the multilayer piezoelectric element 100 is consumed when it is provided in a region other than the node. Increased power.

1.5. The size, material, input signal, etc. of each member The thickness of each piezoelectric layer described above is appropriately set according to the specifications such as the size, material, and application of the laminated piezoelectric element, but 20 μm or more and 200 μm or less, preferably 30 μm It is 180 μm or less and more preferably 50 μm or more and 150 μm or less. If the thickness of the piezoelectric layer is less than 20 μm, the amount of deformation may be insufficient, and if it exceeds 200 μm, the driving voltage may increase and a booster circuit or the like may be required.

The material of each of the above-mentioned piezoelectric layers is not limited as long as it exhibits piezoelectricity, but exhibits a perovskite type crystal structure such as lead zirconate titanate (PZT) and potassium sodium niobate (KNN). An oxide is mentioned. Further, other elements may be added to these compounds.

The above-mentioned various electrodes, wirings, terminals, etc. can be formed by, for example, screen printing on the piezoelectric layer before firing. The thickness of various electrodes, wirings, terminals and the like is, for example, 20 nm or more and 20 μm or less, preferably 100 nm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less. The materials for the electrodes, wirings, terminals and the like are not particularly limited as long as they can be sintered together with the piezoelectric layer to maintain the shape and obtain conductivity. Examples of materials for the electrodes, wirings, terminals and the like include metals and alloys such as silver, gold, platinum, palladium, copper and aluminum, and conductive oxides such as indium stannate (ITO), which may have a multilayer structure.

When operating the laminated piezoelectric element, the signal applied to the expansion/contraction electrode pair 19 and the bending electrode pair 29 is preferably an AC signal having a frequency near the resonance frequency of the laminated piezoelectric element. The voltage of the signal is, for example, 1 Vrms or more and 5 Vrms or less. Further, one of the two electrodes of the expansion/contraction electrode pair 19 may be set to the ground potential, and one of the two electrodes of the bending electrode pair 29 may be set to the ground potential. For example, in the laminated piezoelectric element 100 of the above embodiment, it is preferable that the electrode of the electrode pattern D and the electrode of the electrode pattern E are set to the ground potential.

In addition, it is preferable that the same electric potential is applied to the electrodes arranged with the non-polarizing piezoelectric layer 40 located at the boundary between the bending piezoelectric element 20 and the expansion piezoelectric element 10 interposed therebetween. More preferably, a ground potential is applied.

1.6. Others In the laminated piezoelectric element 100, one of the predetermined electrode patterns B to E is formed on the surface of a plurality of piezoelectric layers, and a plurality of these are laminated and sintered to manufacture a laminated structure 50, and wiring It can be manufactured by providing the layer 80. As shown in FIG. 2, also with respect to the expansion/contraction input terminal 60 and the bending input terminal 70, the electrode of the electrode pattern A is formed on one surface of the corresponding piezoelectric layer, and this is laminated and sintered. It can be formed.

In the embodiment, the laminated piezoelectric element 100 including 12 piezoelectric layers has been described, but the number and arrangement of the piezoelectric layers and the piezoelectric elements included in the element are such that the piezoelectric element 10 for expansion and contraction is the laminated structure. It is not limited as long as it includes the center position G of 50 in the stacking direction. For example, a symmetrical number in the stacking direction may or may not be arranged with reference to the center position G of the stack structure 50 in the stacking direction. Further, the expansion/contraction piezoelectric element 10 may be arranged in addition to the end side in the stacking direction as long as it is arranged at a position including the central position G.

1.7. Function and Effect etc. The laminated piezoelectric element 100 can drive the expansion/contraction piezoelectric element 10 that expands/contracts and vibrates and the bending piezoelectric element 20 that flexurally vibrates by different input signals. As a result, the amplitude and frequency of stretching vibration and bending vibration can be controlled independently. For example, the amplitude of flexural vibration can be changed while maintaining the amplitude of stretching vibration. With this, when the laminated piezoelectric element 100 is applied to a piezoelectric actuator, it is possible to control the operation of a rotating body or a moving body that is an operation target with a high degree of freedom, and without lowering the efficiency of the operation for input, It is possible to carry out an accurate operation.

2. Piezoelectric Actuator The piezoelectric actuator 300 of the present embodiment includes the above-described laminated piezoelectric element 100 and the output extraction member 90 fixed to the laminated piezoelectric element 100. FIG. 10 is a schematic diagram showing an example of a piezoelectric actuator 300 including the laminated piezoelectric element 100.

The piezoelectric actuator 300 of this embodiment includes the laminated piezoelectric element 100 and the output extraction member 90 fixed to one of the side surfaces of the laminated piezoelectric element 100 perpendicular to the longitudinal direction. The output extracting member 90 is a member that is pressed against an object such as a rotating body or a moving body (not shown). The output extraction member 90 can transmit the operation of the piezoelectric actuator 300 to an object. The output extraction member 90 is fixed to the laminated piezoelectric element 100 using, for example, an adhesive. The material of the output extraction member 90 is not particularly limited, but a material having high wear resistance is preferable. The shape of the output extraction member 90 is also arbitrary, and is appropriately designed according to the vibration mode of the laminated piezoelectric element, the property of the operation target, and the like.

Since the piezoelectric actuator 300 of the present embodiment includes the above-described laminated piezoelectric element 100, it is possible to control the operation of the rotating body or the moving body, which is the target of the operation, with a high degree of freedom and reduce the efficiency of the operation with respect to the input. Can be operated accurately without

The present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations having the same function, method and result, or configurations having the same purpose and effect). Further, the invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Further, the invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. Further, the invention includes configurations in which known techniques are added to the configurations described in the embodiments.

10... Expansion/contraction piezoelectric element, 11... First piezoelectric layer, 15... Lead-out part, 16... Both ends, 17... Central part, 18... Constricted part, 19... Expansion/contraction electrode pair, 20... Bending piezoelectric element, 21 ... second piezoelectric layer 25, lead-out portion, 26a, 26b, 26c, 26d... split electrode, 27... connection wiring, 27a, 27b... opening, 29... bending electrode pair, 30... surface piezoelectric layer, 40 ... non-polarizing piezoelectric layer, 50... laminated structure, 60... expansion/contraction input terminal, 70... bending input terminal, 80... wiring layer, 90... output extraction member, 100... laminated piezoelectric element, 110... surface, 112, 113... Side surface, 300... Piezoelectric actuator

Claims

A flat piezoelectric layer having a longitudinal direction and a lateral direction in a plan view includes a laminated structure in which a plurality of layers are laminated in the laminating direction,
The laminated structure is
A first piezoelectric layer that is one of the plurality of piezoelectric layers; and a pair of expansion/contraction electrodes that sandwich the first piezoelectric layer, and the first piezoelectric body is formed by inputting a signal to the pair of expansion/contraction electrodes. A piezoelectric element for expansion and contraction in the longitudinal direction of the layer,
A second piezoelectric body layer, which is one of the plurality of piezoelectric body layers, and a bending electrode pair that sandwiches the second piezoelectric body layer, and the second piezoelectric body is formed by inputting a signal to the bending electrode pair. A bending piezoelectric element that bends in the lateral direction of the layer,
Including
A laminated piezoelectric element in which the elastic piezoelectric element is arranged so as to include a central position of the laminated structure in the laminating direction.
In claim 1,
The laminated structure is
A wiring layer formed on two side surfaces parallel to the longitudinal direction,
The multilayer piezoelectric element, wherein the wiring layer is formed at a position corresponding to a node in bending vibration when the multilayer piezoelectric element operates.
In claim 1 or claim 2,
The bending electrode pair,
On one surface of the second piezoelectric layer, four split electrodes arranged in each of four regions divided into two in the longitudinal direction and the lateral direction of the second piezoelectric layer,
A first electrode for bending, which includes a connection wiring for connecting a pair of divided electrodes arranged diagonally among the four divided electrodes,
A second bending electrode disposed on the other surface of the second piezoelectric layer and facing the first bending electrode with the second piezoelectric layer interposed therebetween;
The second bending electrode includes at least a non-overlapping region that does not overlap with the connection wiring when the bending piezoelectric element is viewed from the stacking direction of the stacked structure.
In claim 3,
The bending second electrode is located at a position corresponding to a space between the divided electrodes facing each other in the longitudinal direction or the lateral direction of the second piezoelectric layer among the plurality of divided electrodes forming the bending first electrode. A laminated piezoelectric element having voids.
In any one of Claim 1 thru|or Claim 4,
The elastic electrode pair,
Formed on the surface of the first piezoelectric layer so as to extend in the longitudinal direction of the first piezoelectric layer;
A laminated piezoelectric element having a constricted portion having a small width of an electrode in the lateral direction between both ends and a central portion in the longitudinal direction of the first piezoelectric layer.
In any one of Claim 1 thru|or 5,
The laminated structure, on the surface of one end side in the stacking direction, is provided with an expansion input terminal connected to the expansion electrode pair, and a bending input terminal connected to the bending electrode pair,
The expansion/contraction input terminal and the bending input terminal are laminated piezoelectric elements formed at positions corresponding to nodes in expansion/contraction vibration or bending vibration when the laminated piezoelectric element operates.
A laminated piezoelectric element according to any one of claims 1 to 6,
An output extraction member fixed to the laminated piezoelectric element,
, A piezoelectric actuator.