JP7125031B2 - Laminated piezoelectric element, piezoelectric vibration device, and electronic equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminated piezoelectric element, a piezoelectric vibrator, and an electronic device that utilize a piezoelectric transverse effect.

In the laminated piezoelectric element, the lateral piezoelectric effect can be effectively utilized by forming a long and narrow shape having a large dimension in the direction orthogonal to the lamination direction. Such a laminated piezoelectric element can be greatly contracted in the longitudinal direction by applying a voltage between external electrodes provided at both ends in the longitudinal direction (see, for example, Patent Document 1).

JP 2016-100760 A International Publication No. 2016/052582

However, since the laminated piezoelectric element has an elongated shape, strong impacts are likely to be applied particularly to both ends in the longitudinal direction during mounting. Therefore, in such a laminated piezoelectric element, both ends in the longitudinal direction are likely to be damaged. Therefore, there is a demand for a technique capable of suppressing the occurrence of damage at both ends in the longitudinal direction of the laminated piezoelectric element.

In view of the circumstances as described above, it is an object of the present invention to provide a laminated piezoelectric element, a piezoelectric vibration device, and an electronic device capable of suppressing the occurrence of damage.

To achieve the above object, a laminated piezoelectric element according to one aspect of the present invention includes a ceramic body, a pair of external electrodes, a plurality of internal electrodes, and surface electrodes.
The ceramic body is formed of piezoelectric ceramics, and includes a pair of end faces facing each other in the longitudinal direction, a pair of main faces facing each other in a thickness direction perpendicular to the longitudinal direction, and a pair of principal faces perpendicular to the longitudinal direction and the thickness direction. and a pair of side surfaces facing each other in the width direction.
The pair of external electrodes cover the pair of end surfaces and extend from the pair of end surfaces along the pair of main surfaces and the pair of side surfaces.
The plurality of internal electrodes are stacked inside the ceramic body along the thickness direction, and are alternately connected to the pair of external electrodes along the thickness direction.
The surface electrodes extend from the pair of external electrodes along the pair of main surfaces, and are divided in the longitudinal direction at positions near the external electrodes connected to the internal electrodes adjacent in the thickness direction. .

In this configuration, the pair of external electrodes extends from the pair of main surfaces and the pair of side surfaces to cover both ends in the longitudinal direction of the laminated piezoelectric element. As a result, both ends of the laminated piezoelectric element are protected by the pair of external electrodes, and are less likely to be damaged. Therefore, in this laminated piezoelectric element, it is possible to suppress the occurrence of damage.

R surfaces may be formed along the ridges of the pair of external electrodes.
A radius of curvature of the R surface may be 10 μm or more.
With these configurations, it is possible to suppress the occurrence of chipping and cracking at the ridges of the pair of external electrodes.

Both ends in the longitudinal direction of the pair of main surfaces may be provided with inclined surfaces that incline inward in the thickness direction toward the pair of end surfaces.
The pair of external electrodes may cover a portion of the inclined surface.
In this configuration, grooves are formed in regions of the inclined surface that are not covered with the pair of external electrodes. As a result, when the laminated piezoelectric element is adhered to a mounting surface such as a diaphragm, the adhesive enters the groove. Therefore, the adhesiveness of the laminated piezoelectric element to the mounting surface is improved.

A piezoelectric vibration device according to one aspect of the present invention includes the laminated piezoelectric element described above, a diaphragm, and an adhesive layer.
The vibration plate faces the laminated piezoelectric element in the thickness direction.
The adhesive layer is arranged between the laminated piezoelectric element and the diaphragm.

An electronic device according to one aspect of the present invention includes the laminated piezoelectric element described above, a panel, and a housing.
The panel is bonded with the laminated piezoelectric elements facing each other in the thickness direction.
The housing holds the panel.

ADVANTAGE OF THE INVENTION According to this invention, the laminated piezoelectric element which can suppress generation|occurrence|production of damage, a piezoelectric vibration apparatus, and an electronic device can be provided.

1 is a perspective view of a laminated piezoelectric element according to one embodiment of the present invention; FIG. 2 is a cross-sectional view of the laminated piezoelectric element taken along line AA' in FIG. 1; FIG. FIG. 2 is a cross-sectional view of the laminated piezoelectric element taken along line BB′ of FIG. 1; 4 is a flow chart showing a method for manufacturing the laminated piezoelectric element. It is a perspective view which shows the manufacturing process of the said laminated piezoelectric element. It is a perspective view which shows the manufacturing process of the said laminated piezoelectric element. FIG. 2 is a cross-sectional view of a piezoelectric vibration device using the laminated piezoelectric element; FIG. 2 is a plan view of an electronic device using the laminated piezoelectric element; 8B is a cross-sectional view of the electronic device taken along line CC' of FIG. 8A. FIG. FIG. 4 is a perspective view of a modified example of the laminated piezoelectric element;

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings show mutually orthogonal X, Y and Z axes where appropriate. The X-axis, Y-axis, and Z-axis are common in all drawings.

[Configuration of Laminated Piezoelectric Element 10]
1 to 3 are diagrams schematically showing the configuration of a laminated piezoelectric element 10 according to one embodiment of the present invention. FIG. 1 is a perspective view of a laminated piezoelectric element 10. FIG. FIG. 2 is a cross-sectional view of the laminated piezoelectric element 10 taken along line AA' in FIG. FIG. 3 is a cross-sectional view of the laminated piezoelectric element 10 taken along line BB' of FIG.

The laminated piezoelectric element 10 has a longitudinal direction along the X-axis, a width direction along the Y-axis, and a thickness direction along the Z-axis. That is, the laminated piezoelectric element 10 is elongated in the X-axis direction. As a result, in the laminated piezoelectric element 10, deformation in the X-axis direction due to the transverse piezoelectric effect is dominant over deformation in the Z-axis direction due to the longitudinal piezoelectric effect.

The laminated piezoelectric element 10 includes a ceramic body 11, first external electrodes 14, and second external electrodes 15. As shown in FIG. The ceramic body 11 has first and second end faces 11a and 11b facing the X-axis direction, first and second side faces 11c and 11d facing the Y-axis direction, and first and second side faces 11c and 11d facing the Z-axis direction. It has two main surfaces 11e and 11f.

The shape of the ceramic body 11 is not limited to the rectangular parallelepiped shape shown in FIGS. For example, the ridge connecting each surface of the ceramic body 11 may be chamfered. Further, each surface of the ceramic body 11 may be curved, and the ceramic body 11 may have a rounded shape as a whole.

The first external electrode 14 covers the first end surface 11a of the ceramic body 11 and extends from the first end surface 11a along the side surfaces 11c and 11d and the main surfaces 11e and 11f. The second external electrode 15 covers the second end surface 11b of the ceramic body 11 and extends from the second end surface 11b along the side surfaces 11c and 11d and the main surfaces 11e and 11f.

The outer surfaces of the external electrodes 14 and 15 are formed with gently curved R surfaces along the curved ridges. The radius of curvature of the R surface along the ridges of the external electrodes 14 and 15 is preferably 10 μm or more. This makes it difficult for the stress applied from the outside to concentrate on the ridges of the external electrodes 14 and 15, thereby suppressing the occurrence of chipping, cracking, and the like.

The external electrodes 14 and 15 are made of a good electrical conductor. Good electrical conductors forming the external electrodes 14 and 15 include, for example, copper (Cu), nickel (Ni), tin (Sn), palladium (Pd), platinum (Pt), silver (Ag), and gold (Au). and the like as a main component.

The ceramic body 11 is made of piezoelectric ceramics having a large absolute value of the piezoelectric constant _d31 . Examples of lead-free materials include lithium niobate (LiNbO ₃ ) and lithium tantalate (LiTaO ₃ ). Examples of lead-based materials include lead zirconate titanate (PbZrO ₃ —PbTiO ₃ ).

A first internal electrode 12 and a second internal electrode 13 are provided inside the ceramic body 11 . The internal electrodes 12 and 13 are sheet-shaped and extend along the XY plane, and are alternately spaced apart along the Z-axis direction. That is, each internal electrode 12, 13 is covered with piezoelectric ceramics.

Therefore, between the internal electrodes 12 and 13, a ceramic layer 18, which is a layer of piezoelectric ceramics, is formed. The first internal electrode 12 is drawn out to the first end surface 11 a of the ceramic body 11 and connected to the first external electrode 14 . The second internal electrode 13 is drawn out to the second end surface 11 b of the ceramic body 11 and connected to the second external electrode 15 .

As shown in FIG. 3, the internal electrodes 12 and 13 are spaced apart from the side surfaces 11c and 11d. That is, the ceramic element body 11 is provided with side margin portions that form spaces between the internal electrodes 12 and 13 and the side surfaces 11c and 11d. This ensures insulation of the internal electrodes 12 and 13 on the side surfaces 11c and 11d.

In the ceramic body 11, a first surface electrode 16 is provided on the first main surface 11e, and a second surface electrode 17 is provided on the second main surface 11f. As a result, between the uppermost second internal electrode 13 and the first surface electrode 16 in the Z-axis direction, and between the lowermost first internal electrode 12 and the second surface electrode 17 in the Z-axis direction. A ceramic layer 18 is formed.

The first surface electrode 16 is separated from the first functional portion 16a on the first external electrode 14 side and the second external electrode 15 side by a gap D formed at a position closer to the second external electrode 15 than the central portion in the X-axis direction. and the first dummy portion 16b. The dimension in the X-axis direction of the first functional portion 16a is larger than that of the first dummy portion 16b.

The second surface electrode 17 has a second functional portion 17a on the second external electrode 15 side and a second functional portion 17a on the first external electrode 14 side by a gap D formed at a position closer to the first external electrode 14 than the central portion in the X-axis direction. and the second dummy portion 17b. The dimension in the X-axis direction of the second functional portion 17a is larger than that of the second dummy portion 17b.

The internal electrodes 12, 13 and the surface electrodes 16, 17 are each made of a good electrical conductor. Examples of good electrical conductors forming the internal electrodes 12, 13 and surface electrodes 16, 17 include nickel (Ni), copper (Cu), palladium (Pd), platinum (Pt), silver (Ag), and gold (Au). and the like as a main component.

With the above configuration, in the laminated piezoelectric element 10 , when voltage is applied between the first external electrode 14 and the second external electrode 15 , voltage in the Z-axis direction is applied to all the ceramic layers 18 . As a result, each ceramic layer 18 contracts in the X-axis direction, so that the laminated piezoelectric element 10 as a whole contracts in the X-axis direction.

The first functional portion 16 a of the first surface electrode 16 connected to the first external electrode 14 can apply a voltage to the ceramic layer 18 between the first surface electrode 16 and the second internal electrode 13 . On the other hand, the first dummy portion 16b connected to the second external electrode 15 cannot apply voltage to the ceramic layer 18 between the second internal electrode 13 and the first dummy portion 16b.

Also, the second functional portion 17 a of the second surface electrode 17 connected to the second external electrode 15 can apply a voltage to the ceramic layer 18 between the second surface electrode 17 and the first internal electrode 12 . On the other hand, the second dummy portion 17b connected to the first external electrode 14 cannot apply voltage to the ceramic layer 18 between the first internal electrode 12 and the second dummy portion 17b.

Therefore, in the laminated piezoelectric element 10, the greater the dimension of the functional portions 16a and 17a in the X-axis direction, the greater the shrinkage in the X-axis direction. Therefore, in the laminated piezoelectric element 10, it is preferable to keep the dimension of the dummy portions 16b and 17b small in the X-axis direction in order to increase the dimension of the functional portions 16a and 17a in the X-axis direction.

The laminated piezoelectric element 10 can be widely used as a piezoelectric actuator that operates in the X-axis direction by the piezoelectric lateral effect. An example of the application of the laminated piezoelectric element 10 is a piezoelectric vibration device. A piezoelectric vibration device is typically configured by combining a laminated piezoelectric element 10 with a vibration plate made of metal.

More specifically, in the piezoelectric vibration device, for example, the first main surface 11e side or the second main surface 11f side of the laminated piezoelectric element 10 is adhered to the mounting surface of the diaphragm. In the piezoelectric vibrating device, the diaphragm can be vibrated by applying a voltage of a predetermined frequency between the external electrodes 14 and 15 to expand and contract the laminated piezoelectric element 10 in the longitudinal direction.

In the laminated piezoelectric element 10, both ends in the longitudinal direction are likely to collide with the mounting surface during mounting. In this respect, both ends of the laminated piezoelectric element 10 in the longitudinal direction are protected by the external electrodes 14 and 15, so that they are less likely to be damaged. Furthermore, since the ridges of the external electrodes 14 and 15 are rounded, chipping and cracking are less likely to occur.

Moreover, since the surface electrodes 16 and 17 are provided with the dummy portions 16b and 17b, the heights of the external electrodes 14 and 15 on the main surfaces 11e and 11f in the Z-axis direction can be easily aligned. That is, a step in the Z-axis direction between the first external electrode 14 and the second external electrode 15 is less likely to occur. Therefore, in the laminated piezoelectric element 10, inclination with respect to the mounting surface can be suppressed.

Furthermore, in the laminated piezoelectric element 10, since the external electrodes 14 and 15 are arranged on the main surfaces 11e and 11f, a gap is formed between the ceramic body 11 and the mounting surface. As a result, in the laminated piezoelectric element 10, the ceramic body 11 is less likely to be subjected to impact from the mounting surface, so that the ceramic body 11 is prevented from being damaged.

The configuration of the laminated piezoelectric element 10 according to this embodiment is not limited to the configurations shown in FIGS. 1 to 3, and can be changed as appropriate. For example, the number of internal electrodes 12 and 13 and the thickness of the ceramic layer 18 can be appropriately determined according to the application of the laminated piezoelectric element 10 or the like. Also, the configuration of the surface electrodes 16 and 17 is determined according to the configuration of the internal electrodes 12 and 13 .

Specifically, when the first internal electrode 12 is arranged at the uppermost portion in the Z-axis direction, the arrangement of the first functional portion 16a and the first dummy portion 16b in the first surface electrode 16 in the X-axis direction is as shown in FIG. Opposite to 2. That is, the first functional portion 16 a is connected to the second internal electrode 13 and the first dummy portion 16 b is connected to the first internal electrode 12 .

Further, when the second internal electrode 13 is arranged at the bottom in the Z-axis direction, the arrangement of the second functional portion 17a and the second dummy portion 17b in the second surface electrode 17 in the X-axis direction is the same as in FIG. is the opposite. That is, the second functional portion 17 a is connected to the first internal electrode 12 and the second dummy portion 17 b is connected to the second internal electrode 13 .

[Manufacturing Method of Laminated Piezoelectric Element 10]
FIG. 4 is a flow chart showing a method for manufacturing the laminated piezoelectric element 10. As shown in FIG. 5 and 6 are diagrams showing the manufacturing process of the laminated piezoelectric element 10. FIG. Hereinafter, a method for manufacturing the laminated piezoelectric element 10 will be described along FIG. 4 and with appropriate reference to FIGS.

(Step S01: Fabrication of ceramic body)
In step S01, a ceramic body 11 is produced. In step S01, first, ceramic sheets 101, 102, 103, and 104 shown in FIG. 5 are prepared. The ceramic sheets 101, 102, 103, and 104 are piezoelectric green sheets containing piezoelectric ceramics as a main component.

A piezoelectric green sheet is obtained by molding a ceramic slurry obtained by mixing calcined powder of piezoelectric ceramics, a binder made of an organic polymer, and a plasticizer into a sheet. A roll coater, a doctor blade, or the like, for example, can be used to form the piezoelectric green sheet.

A conductive paste is applied in a predetermined pattern to each of the ceramic sheets 101, 102, 103, 104, and unfired internal electrodes 12, 13 and surface electrodes 16, 17 are formed. For example, a screen printing method, a gravure printing method, or the like can be used to apply the conductive paste.

Specifically, the first internal electrodes 12 are formed on the ceramic sheet 101 . A second internal electrode 13 is formed on the ceramic sheet 102 . A first surface electrode 16 is formed on the ceramic sheet 103 . A first internal electrode 12 and a second surface electrode 17 are formed on the ceramic sheet 104 .

Then, the ceramic sheets 101, 102, 103 and 104 are laminated in the Z-axis direction in the order shown in FIG. For thermocompression bonding of the ceramic sheets 101, 102, 103, 104, for example, uniaxial pressurization or hydrostatic pressure pressurization can be used.

Subsequently, the unfired ceramic body 11 is heated to, for example, 300 to 500° C. to remove the binder. Then, the ceramic body 11 after the binder removal treatment is sintered by heating to, for example, 900 to 1200.degree. Thereby, the ceramic body 11 shown in FIG. 6 is obtained.

(Step S02: External electrode formation)
In step S02, external electrodes 14 and 15 are formed on the ceramic body 11 obtained in step S01, thereby producing the laminated piezoelectric element 10 shown in FIGS. In step S02, for example, the external electrodes 14 and 15 can be formed by baking the conductive paste applied to both ends of the ceramic body 11 in the longitudinal direction.

A dipping method, for example, can be used to apply the conductive paste. In the dipping method, both ends of the ceramic body 11 in the X-axis direction are immersed in the conductive paste. As a result, unsintered external electrodes 14 and 15 extending from the end surfaces 11a and 11b along the side surfaces 11c and 11d and the main surfaces 11e and 11f are formed.

The ridges of the external electrodes 14 and 15 applied by the dipping method form rounded surfaces due to the surface tension of the conductive paste. Note that the method of applying the conductive paste is not limited to the dipping method, and any known method can be employed as appropriate. Methods of applying the conductive paste other than the dipping method include, for example, various printing methods.

Then, by heating the unfired external electrodes 14 and 15 formed at both ends of the ceramic body 11 in the X-axis direction, the external electrodes 14 and 15 are baked onto the ceramic body 11 . As a result, the external electrodes 14 and 15 are sintered, and the laminated piezoelectric element 10 according to this embodiment shown in FIGS. 1 to 3 is obtained.

Note that the processing in step S02 can also be performed in step S01. For example, a conductive paste may be applied to both ends of the unfired ceramic body 11 in the X-axis direction. Thereby, the firing of the ceramic body 11 and the firing of the external electrodes 14 and 15 can be performed at the same time.

(Step S03: Polarization processing)
In step S03, the laminated piezoelectric element 10 is subjected to a polarization process. Specifically, in the polarization process, by applying a DC high electric field in the Z-axis direction to the laminated piezoelectric element 10, the direction of spontaneous polarization of the piezoelectric ceramics constituting the ceramic layer 18 is aligned. As a result, piezoelectric activity is imparted to the piezoelectric ceramics, and the laminated piezoelectric element 10 can exhibit its function.

[Piezoelectric vibration device 20]
The laminated piezoelectric element 10 can be widely used as a piezoelectric actuator that operates in the X-axis direction by the piezoelectric lateral effect. An example of the application of the laminated piezoelectric element 10 is a piezoelectric vibration device that generates vibration. A unimorph-type piezoelectric vibration device 20 configured using the laminated piezoelectric element 10 will be described below.

FIG. 7 is a cross-sectional view of the piezoelectric vibration device 20. As shown in FIG. The piezoelectric vibration device 20 includes a laminated piezoelectric element 10 , a vibration plate 21 and an adhesive layer 22 . The vibration plate 21 is configured as a flat plate extending along the XY plane and arranged to face the first main surface 11e of the laminated piezoelectric element 10 . The adhesive layer 22 is arranged between the laminated piezoelectric element 10 and the vibration plate 21 .

The diaphragm 21 is made of, for example, metal or glass, and has flexibility in the Z-axis direction. The adhesive layer 22 is formed of a resin material or the like, and bonds the laminated piezoelectric element 10 and the vibration plate 21 together. The adhesive layer 22 is in close contact with the lower portion of the laminated piezoelectric element 10 in the Z-axis direction and in close contact with the upper surface of the vibration plate 21 in the Z-axis direction.

The adhesive layer 22 is filled between the first main surface 11e of the ceramic body 11 and the diaphragm 21, and bonds the ceramic body 11 and the diaphragm 21 over a wide range. As a result, in the piezoelectric vibration device 20, a high bonding strength can be obtained between the laminated piezoelectric element 10 and the vibration plate 21 via the adhesive layer 22. As shown in FIG.

In the piezoelectric vibration device 20, since the bonding strength between the laminated piezoelectric element 10 and the diaphragm 21 by the adhesive layer 22 is high, even when the laminated piezoelectric element 10 is greatly expanded and contracted, the laminated piezoelectric element 10 is separated from the diaphragm 21. Not easy to peel off. Therefore, in the piezoelectric vibration device 20, the large vibration of the vibration plate 21 is maintained.

[Electronic device 30]
8A and 8B are diagrams schematically showing an electronic device 30 using the laminated piezoelectric element 10. FIG. 8A is a plan view of the electronic device 30. FIG. FIG. 8B is a cross-sectional view of the electronic device 30 taken along line CC' of FIG. 8A. The electronic device 30 is configured as a multifunctional mobile communication terminal generally called a smart phone.

The electronic device 30 has a laminated piezoelectric element 10 , a housing 31 and a panel 32 . The housing 31 has a rectangular bottom plate 31a extending along the XY plane and a frame 31b extending upward in the Z-axis direction from the periphery of the bottom plate 31a, and is formed in a box shape that is open upward in the Z-axis direction. ing. The panel 32 extends rectangularly along the XY plane and closes the housing 31 from above in the Z-axis direction.

The housing 31 accommodates components (not shown) such as circuit boards and electronic components for realizing various functions of the electronic device 30 . The panel 32 is configured as a touch panel. In other words, the panel 32 has both an image display function of displaying an image and an input function of detecting an input operation by a user's finger or the like.

Note that the panel 32 is not limited to a touch panel, and may not have the above configuration. For example, the panel 32 may be a touch pad that has only an input function without an image display function. Also, the panel 32 may be a protection panel that protects a touch panel separately provided on the electronic device 30 .

The laminated piezoelectric element 10 is adhered to the lower surface of the panel 32 in the Z-axis direction and faces the bottom plate 31a inside the housing 31 . The position of the laminated piezoelectric element 10 on the lower surface of the panel 32 in the Z-axis direction can be determined arbitrarily. In the electronic device 30, the panel 32 functions as the diaphragm 21 in the piezoelectric vibration device 20 shown in FIG.

That is, the electronic device 30 can vibrate the panel 32 by expanding and contracting the laminated piezoelectric element 10 in the X-axis direction. For this reason, it is preferable that the panel 32 is mainly made of glass, acrylic resin, or the like, which can vibrate satisfactorily. Moreover, the adhesive layer that bonds the laminated piezoelectric element 10 and the panel 32 preferably has the same configuration as the adhesive layer 22 of the piezoelectric vibration device 20 .

The electronic device 30 can provide audio information to the user by vibrating the panel 32 and generating sound through air conduction, bone conduction, or the like. Further, the electronic device 30 can present a tactile sensation to a user who performs an input operation on the panel 32, for example, by vibrating the panel 32. FIG.

Although the top surface of the panel 32 in the Z-axis direction is typically flat, it may be curved, for example. Further, the electronic device 30 is not limited to a smart phone, and may be configured as, for example, a tablet terminal, a notebook computer, a mobile phone, a wristwatch, a photo stand, a remote controller or an operation unit of various devices.

[Other embodiments]
Although the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above-described embodiments and can be modified in various ways. As an example, a laminated piezoelectric element 10 according to a modification of the above embodiment will be described below.

FIG. 9 is a cross-sectional view of a laminated piezoelectric element 10 according to a modification of the above embodiment. In the laminated piezoelectric element 10 according to the modified example, first inclined surfaces 11e1 and 11e2 are provided at both ends of the first main surface 11e in the X-axis direction, and second inclined surfaces 11e1 and 11e2 are provided at both ends of the second main surface 11f in the X-axis direction. Surfaces 11f1 and 11f2 are provided.

The first inclined surfaces 11e1 and 11e2 provided at both ends of the first main surface 11e in the X-axis direction are inclined downward in the Z-axis direction toward the end surfaces 11a and 11b. The second inclined surfaces 11f1 and 11f2 provided at both ends of the second main surface 11f in the X-axis direction are inclined upward in the Z-axis direction toward the end surfaces 11a and 11b.

The first external electrode 14 extends from the first end surface 11a of the ceramic body 11 to the middle of the inclined surfaces 11e1 and 11f1, and partially covers the inclined surfaces 11e1 and 11f1. Further, the second external electrode 15 extends from the second end face 11b of the ceramic body 11 to the middle of the inclined surfaces 11e2 and 11f2, and partially covers the inclined surfaces 11e2 and 11f2.

Therefore, the regions inside the inclined surfaces 11e1, 11e2, 11f1, and 11f2 in the X-axis direction are not covered with the external electrodes 14 and 15. FIG. For this reason, a groove portion C is formed in each of the inclined surfaces 11e1, 11e2, 11f1, and 11f2, the outer sides of which are separated by the external electrodes 14 and 15 in the X-axis direction. Each groove C is recessed in the Z-axis direction and extends along the Y-axis direction.

In the laminated piezoelectric element 10 according to the modified example, either the first main surface 11e side or the second main surface 11f side is adhered to a mounting surface such as a diaphragm (for example, the diaphragm 21 shown in FIG. 7) with an adhesive. The adhesive is filled in the groove portion C when the adhesive is applied. As a result, in the laminated piezoelectric element 10, since the bonding strength of the adhesive to the mounting surface is improved, high adhesiveness to the mounting surface can be obtained.

DESCRIPTION OF SYMBOLS 10... Laminated piezoelectric element 11... Ceramic element body 11a, 11b... End surface 11c, 11d... Side surface 11e, 11f... Main surface 12, 13... Internal electrode 14, 15... External electrode 16, 17... Surface electrode 16a, 17a... Function part DESCRIPTION OF SYMBOLS 16b, 17b... Dummy part 18... Ceramic layer 20... Piezoelectric vibration apparatus 21... Diaphragm 22... Adhesive layer 30... Electronic device 31... Case 32... Panel

Claims (6)

A pair of end faces facing each other in the longitudinal direction, a pair of principal faces facing each other in a thickness direction perpendicular to the longitudinal direction, and a width direction facing each other perpendicular to the longitudinal direction and the thickness direction are formed of piezoelectric ceramics. a ceramic body having a pair of side surfaces;
a pair of external electrodes directly covering the pair of end surfaces and extending from the pair of end surfaces along the pair of main surfaces and the pair of side surfaces;
a plurality of internal electrodes stacked along the thickness direction inside the ceramic body and alternately connected to the pair of external electrodes along the thickness direction;
a surface electrode extending from the pair of external electrodes along the pair of main surfaces and divided in the longitudinal direction at a position closer to the external electrode connected to the internal electrodes adjacent in the thickness direction;
and
Portions of the pair of external electrodes that extend along the pair of main surfaces overlap the surface electrodes.
Laminated piezoelectric element. The laminated piezoelectric element according to claim 1,
A laminated piezoelectric element, in which an R surface is formed along the ridges of the pair of external electrodes. The laminated piezoelectric element according to claim 2,
A laminated piezoelectric element, wherein the radius of curvature of the R surface is 10 μm or more. The laminated piezoelectric element according to any one of claims 1 to 3,
Both ends of the pair of main surfaces in the longitudinal direction are provided with inclined surfaces that incline inward in the thickness direction toward the pair of end surfaces,
The pair of external electrodes is a laminated piezoelectric element covering a part of the inclined surface. A laminated piezoelectric element according to any one of claims 1 to 4;
a diaphragm facing the laminated piezoelectric element in the thickness direction;
an adhesive layer disposed between the laminated piezoelectric element and the diaphragm;
A piezoelectric vibration device comprising: A laminated piezoelectric element according to any one of claims 1 to 4;
a panel to which the laminated piezoelectric elements are bonded while facing each other in the thickness direction;
a housing that holds the panel;
An electronic device comprising

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