Piezoelectric element

Abstract

The invention relates to a piezoelectric element. The piezoelectric element includes a piezoelectric element body. The piezoelectric element body includes a first region including a first main surface and a second region including a second main surface opposite to the first main surface. The piezoelectric element includes a first internal electrode group disposed in the first region and a second internal electrode group disposed in the second region. The first internal electrode group and the second internal electrode group each include a plurality of internal electrodes facing each other in a direction in which the first main surface and the second main surface face each other. The internal electrode closest to the second region among the plurality of internal electrodes included in the first internal electrode group and the internal electrode closest to the first region among the plurality of internal electrodes included in the second internal electrode group are electrically connected to each other.

Description

Technical Field

[0001] This invention relates to a piezoelectric element. Background Technology

[0002] Known piezoelectric elements include an electrode and two piezoelectric elements disposed on both sides of the electrode (for example, see Japanese Patent Application Laid-Open No. 2005-318725). The two piezoelectric elements are displaced by the application of a voltage. Summary of the Invention

[0003] The purpose of this invention is to provide a piezoelectric element that can alleviate stress acting on a piezoelectric element.

[0004] One aspect of the piezoelectric element of the present invention includes: a piezoelectric element comprising a first main surface and a second main surface opposite to each other, and a side surface connecting the first main surface and the second main surface, and including a first region including the first main surface and a second region including the second main surface; a first internal electrode group disposed in the first region and including a plurality of internal electrodes opposite to each other in a direction opposite to the first main surface and the second main surface; and a second internal electrode group disposed in the second region and including a plurality of internal electrodes opposite to each other in a direction opposite to the first main surface and the second main surface. The internal electrode closest to the second region among the plurality of internal electrodes included in the first internal electrode group is electrically connected to the internal electrode closest to the first region among the plurality of internal electrodes included in the second internal electrode group.

[0005] In one of the above embodiments, the first internal electrode group includes a plurality of internal electrodes facing each other within a first region, and the first region includes a region located between the plurality of internal electrodes facing each other. The second internal electrode group includes a plurality of internal electrodes facing each other within a second region, and the second region includes a region located between the plurality of internal electrodes facing each other. Hereinafter, the region located between the plurality of internal electrodes facing each other is sometimes referred to as the "interelectrode region".

[0006] When a voltage is applied, an electric field is generated in the inter-electrode regions contained in the first and second regions, and these inter-electrode regions may displace. In one of the above methods, the internal electrode closest to the second region is electrically connected to the internal electrode closest to the first region. Therefore, when a voltage is applied, it is difficult to generate an electric field in the region between the internal electrodes closest to the second region and the internal electrodes closest to the first region, i.e., the region between the first and second regions, and it is difficult for this region to displace. When the inter-electrode regions contained in the first and second regions displace, the region between the first and second regions alleviates the stress acting on the second region through displacement in the first region, and alleviates the stress acting on the first region through displacement in the second region. This method can alleviate the stress acting on the piezoelectric element.

[0007] Another aspect of the piezoelectric element of the present invention includes: a piezoelectric element comprising a first main surface and a second main surface opposite to each other, and a side surface connecting the first main surface and the second main surface, and comprising a first region including the first main surface and a second region including the second main surface; a first internal electrode group disposed in the first region and comprising a plurality of internal electrodes opposite to each other in a direction opposite to the first main surface and the second main surface; a second internal electrode group disposed in the second region and comprising a plurality of internal electrodes opposite to each other in a direction opposite to the first main surface and the second main surface; and an internal conductor disposed between the internal electrode closest to the second region among the plurality of internal electrodes included in the first internal electrode group and the internal electrode closest to the first region among the plurality of internal electrodes included in the second internal electrode group, and not electrically connected to the plurality of internal electrodes included in the first internal electrode group and the plurality of internal electrodes included in the second internal electrode group.

[0008] In another embodiment described above, the piezoelectric element comprises a region between the inner electrode closest to the second region among the plurality of inner electrodes included in the first inner electrode group and the inner electrode closest to the first region among the plurality of inner electrodes included in the second inner electrode group, i.e., between the first and second regions. In this other embodiment, the inner conductor is disposed in the region between the first and second regions and is not electrically connected to the plurality of inner electrodes included in the first and second inner electrode groups. Therefore, when a voltage is applied, it is difficult to generate an electric field in the region between the first and second regions. The region between the first and second regions is difficult to displace. The region between the first and second regions mitigates the stress acting on the second region through displacement in the first region, and mitigates the stress acting on the first region through displacement in the second region. This other embodiment can mitigate the stress acting on the piezoelectric element.

[0009] The invention will be more fully understood from the detailed description and accompanying drawings given below, which are given by way of illustration only and should not be considered as limiting the invention.

[0010] The further applicability of the invention will become apparent from the detailed description given below. However, it should be understood that while the detailed description and specific examples indicate embodiments of the invention, they are given by way of illustration only, as various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. Attached Figure Description

[0011] Figure 1 This is a perspective view of a vibrating device that includes a piezoelectric element in one embodiment.

[0012] Figure 2 This is a diagram showing the cross-sectional structure of the piezoelectric element according to this embodiment.

[0013] Figure 3 This is an exploded perspective view of the piezoelectric element in this embodiment.

[0014] Figure 4 This is an exploded perspective view of the piezoelectric element in this embodiment.

[0015] Figure 5 This is an exploded perspective view of the piezoelectric element in this embodiment.

[0016] Figure 6 This is a diagram showing the cross-sectional structure of a piezoelectric element in a modified example of this embodiment.

[0017] Figure 7 This is an exploded perspective view of the piezoelectric element in a modified embodiment of this invention.

[0018] Figure 8 This is a diagram showing the cross-sectional structure of a piezoelectric element according to another embodiment. Detailed Implementation

[0019] In the following description, embodiments of the invention will be described in detail with reference to the accompanying drawings. In the description below, the same elements or elements having the same function are denoted by the same reference numerals, and repeated descriptions are omitted.

[0020] Reference Figures 1-5 The structure of a piezoelectric element according to one embodiment will be described. Figure 1 This is a perspective view of a vibrating device including the piezoelectric element of this embodiment. Figure 2 This is a diagram showing the cross-sectional structure of the piezoelectric element according to this embodiment. Figure 3 , Figure 4 and Figure 5This is an exploded perspective view of the piezoelectric element in this embodiment.

[0021] like Figure 1 As shown, the vibrating device 1 includes a piezoelectric element 10, a vibrating component 50, and a wiring component 60. Figure 1 In order to make the piezoelectric element 10 easy to understand, the wiring component 60 is illustrated with a double-dotted line.

[0022] The structure of the piezoelectric element 10 is described below. The piezoelectric element 10 includes a piezoelectric core 11, multiple external electrodes 13, 14, and 15, and multiple connecting conductors 30, 31, and 32. For example, the piezoelectric element 10 includes three external electrodes 13, 14, and 15 and three connecting conductors 30, 31, and 32. Connecting conductor 30 is connected to external electrode 13. Connecting conductor 31 is connected to external electrode 14. Connecting conductor 32 is connected to external electrode 15. The piezoelectric element 10 includes a dual piezoelectric wafer type element.

[0023] The piezoelectric element 11 is in the shape of a cuboid. The cuboid shape includes a cuboid shape with chamfered corners and edges, or a cuboid shape with rounded corners and edges. The piezoelectric element 11 includes two main faces 11a and 11b that are opposite each other, a pair of side faces 11c that are opposite each other, and a pair of side faces 11e that are opposite each other.

[0024] Main surfaces 11a and 11b face each other in a first direction D1. Main surfaces 11a and 11b are orthogonal to the first direction D1. A pair of side surfaces 11c face each other in a second direction D2. A pair of side surfaces 11e face each other in a third direction D3. The pair of side surfaces 11c and the pair of side surfaces 11e extend in the first direction D1 in a manner connecting the pair of main surfaces 11a and 11b. The pair of side surfaces 11c and the pair of side surfaces 11e are adjacent to each other. For example, the surface of the piezoelectric element 11 includes main surfaces 11a and 11b and side surfaces 11c and 11e.

[0025] Main faces 11a and 11b, a pair of side faces 11c, and a pair of side faces 11e are each rectangular in shape. The rectangular shape includes shapes with chamfered corners or rounded corners. For example, if main face 11a includes a first main face, then main face 11b includes a second main face.

[0026] The length of the piezoelectric element 11 in the first direction D1 is, for example, 0.3 to 2 mm. The length of the piezoelectric element 11 in the second direction D2 is, for example, 5 to 70 mm. The length of the piezoelectric element 11 in the third direction D3 is, for example, 5 to 70 mm. In the piezoelectric element 11, for example, the second direction D2 is the long side direction. The second direction D2 intersects the first direction D1. The third direction D3 intersects the first direction D1 and the second direction D2. For example, the first direction D1, the second direction D2, and the third direction D3 are orthogonal to each other.

[0027] External electrodes 13, 14, and 15 are disposed on the main surface 11a. External electrodes 13, 14, and 15 are arranged in the second direction D2 in the order of external electrodes 13, 14, and 15. External electrodes 13 and 14 are adjacent to each other in the second direction D2. External electrodes 14 and 15 are also adjacent to each other in the second direction D2. In the second direction D2, the shortest distance between external electrodes 14 and 15 is, for example, longer than the shortest distance between external electrodes 13 and 14. Viewed from the first direction D1, external electrodes 13, 14, and 15 are separated from the side surfaces 11c and 11e.

[0028] The external electrodes 13, 14, and 15 are rectangular. For example, the external electrodes 13, 14, and 15 are rectangular with rounded corners. The external electrodes 13, 14, and 15 may also be square. The external electrodes 13, 14, and 15 contain a conductive material. The conductive material may contain, for example, Ag, Pd, Pt, or an Ag-Pd alloy. The external electrodes 13, 14, and 15 may be configured, for example, as a sintered body of a conductive paste containing the aforementioned conductive material.

[0029] like Figures 2-5 As shown, the piezoelectric element 11 includes region R1 and region R2. Region R1 includes a main surface 11a, and region R2 includes a main surface 11b. Region R1 is located near the main surface 11a, and region R2 is located near the main surface 11b. Regions R1 and R2 are separated from each other in a first direction D1. For example, the piezoelectric element 11 includes region R3. Region R3 is located between region R1 and region R2 in the first direction D1. Region R3 does not include the main surfaces 11a and 11b. For example, if region R1 includes a first region, region R2 includes a second region.

[0030] The piezoelectric element 11 comprises a plurality of piezoelectric layers 17. The plurality of piezoelectric layers 17 are stacked in a first direction D1. Regions R1 and R2 each comprise a plurality of piezoelectric layers 17. Region R1, for example, comprises seven piezoelectric layers 17. Region R2, for example, comprises seven piezoelectric layers 17. The piezoelectric layer 17 in region R1 closest to the main surface 11a contains the main surface 11a. The piezoelectric layer 17 in region R2 closest to the main surface 11b contains the main surface 11b. In regions R1 and R2, the piezoelectric layers 17 are polarized. In the first direction D1, piezoelectric layers 17 with opposite polarization directions are alternately arranged. For example, the thickness of each of the plurality of piezoelectric layers 17 is the same. In this specification, "same" does not simply mean that the multiple values ​​are necessarily identical. Even when there are minor differences, manufacturing errors, or measurement errors within a predetermined range, the multiple values ​​can be set to be the same. For example, if multiple values ​​converge to within ±10% of the average of those values, then those values ​​are defined as "identical" to each other.

[0031] The piezoelectric element 10 includes an internal electrode group 20 and an internal electrode group 22. The internal electrode group 20 and the internal electrode group 22 are separated from each other in a first direction D1.

[0032] The internal electrode assembly 20 is disposed in region R1. For example... Figure 2 and Figure 3 As shown, the internal electrode group 20 includes a plurality of internal electrodes 21 and 25. Internal electrodes 25 are opposite to internal electrodes 21. The plurality of internal electrodes 21 and 25 are opposite to each other in a first direction D1. The internal electrodes 21 and 25 are respectively disposed at different positions (layers) in the first direction D1. For example, the internal electrode group 20 includes three internal electrodes 21 and four internal electrodes 25. In the internal electrode group 20, the internal electrodes 21 and 25 are arranged alternately, and the internal electrodes 21 and 25 are opposite to each other with a spacing L1, separated by a corresponding piezoelectric layer 17 from a plurality of piezoelectric layers 17. The spacing L1 between the internal electrodes 21 and 25 is the same. Figure 3 This represents the structure of region R1.

[0033] The internal electrode group 20 includes the internal electrode 25 closest to region R2 among the plurality of internal electrodes 21, 25 contained in the internal electrode group 20. The internal electrode group 20 includes the internal electrode 25 closest to the main surface 11a among the plurality of internal electrodes 21, 25 contained in the internal electrode group 20.

[0034] Internal electrode assembly 22 is disposed in region R2. For example... Figure 2 and Figure 5 As shown, the internal electrode group 22 includes multiple internal electrodes 23 and 25. Internal electrodes 23 are not electrically connected to the multiple internal electrodes 21 and 25 included in the internal electrode group 20. Internal electrodes 25 are opposite to internal electrodes 23. The multiple internal electrodes 23 and 25 are opposite to each other in the first direction D1. The internal electrodes 25 included in the internal electrode group 22 are electrically connected to the internal electrodes 25 included in the internal electrode group 20. The internal electrodes 23 and 25 are respectively disposed at different positions (layers) in the first direction D1. For example, the internal electrode group 22 includes three internal electrodes 23 and four internal electrodes 25. In the internal electrode group 22, the internal electrodes 23 and 25 are arranged alternately, and the internal electrodes 23 and 25 are opposite to each other with a gap L2 separated by a corresponding piezoelectric layer 17. The gap L2 between the multiple internal electrodes 23 and 25 is the same size. Figure 5 This represents the structure of region R2.

[0035] The internal electrode group 22 includes the internal electrode 25 closest to region R1 among the plurality of internal electrodes 23, 25 contained in the internal electrode group 22. The internal electrode group 22 includes the internal electrode 25 closest to the main surface 11b among the plurality of internal electrodes 23, 25 contained in the internal electrode group 22.

[0036] The internal electrode 25 of the closest region R1 among the plurality of internal electrodes 23, 25 included in the internal electrode group 22 is electrically connected to the internal electrode 25 of the closest region R2 among the plurality of internal electrodes 21, 25 included in the internal electrode group 20.

[0037] For example, if the internal electrode group 20 includes a first internal electrode group, the internal electrode group 22 includes a second internal electrode group. For example, if the internal electrode 21 includes a first internal electrode, the internal electrode 25 included in the internal electrode group 20 includes a second internal electrode. For example, if the internal electrode 23 includes a third internal electrode, the internal electrode 25 included in the internal electrode group 22 includes a fourth internal electrode.

[0038] In the internal electrode groups 20 and 22, the internal electrodes 21, 23, and 25 are not exposed on the surface of the piezoelectric element 11. The internal electrodes 21, 23, and 25 are not exposed on the main surfaces 11a and 11b and the side surfaces 11c and 11e. The internal electrodes 21, 23, and 25 are separated from the main surfaces 11a and 11b and the side surfaces 11c and 11e.

[0039] Region R3 is located between the internal electrode 25 closest to region R2 in internal electrode group 20 and the internal electrode 25 closest to region R1 in internal electrode group 22. Region R3 includes multiple piezoelectric layers 19. Region R3 includes, for example, two piezoelectric layers 19. The piezoelectric layer 19 is located between the piezoelectric layer 17 included in region R1 and the piezoelectric layer 17 included in region R2. In the piezoelectric body 11, multiple piezoelectric layers 17, 19 are stacked on a first direction D1. The thickness of each piezoelectric layer 19 is the same. The piezoelectric layer 19 is substantially unpolarized.

[0040] like Figure 2 and Figure 4 As shown, the piezoelectric element 10 includes an internal conductor 27. The internal conductor 27 is disposed in region R3. The piezoelectric element 10 includes, for example, a single internal conductor 27. The internal conductor 27 is not electrically connected to the plurality of internal electrodes 21, 25 included in the internal electrode group 20 and the plurality of internal electrodes 23, 25 included in the internal electrode group 22. The internal conductor 27 is not exposed on the surface of the piezoelectric element 11. The internal conductor 27 is not exposed on the sides 11c, 11e. The internal conductor 27 is separated from the sides 11c, 11e. Figure 4 This indicates the structure of region R3.

[0041] The internal conductor 27 is disposed between the internal electrode 25 closest to region R2 in the internal electrode group 20 and the internal electrode 25 closest to region R1 in the internal electrode group 22. The internal conductor 27 is located in region R3. The internal electrode 25 closest to region R2 and the internal electrode 25 closest to region R1 are separated by a distance L3 in the first direction D1. The distance L3 corresponds to the length of region R3 in the first direction D1. The distance L3 is greater than the distances L1 and L2. The piezoelectric element 10 may also not include the internal conductor 27. Even if the piezoelectric element 10 has a structure that does not include the internal conductor 27, the distance L3 is still greater than the distances L1 and L2.

[0042] Piezoelectric layers 17 and 19 comprise piezoelectric materials. For example, piezoelectric ceramic materials may be included. These materials may include, for example, PZT[Pb(Zr,Ti)O3], PT(PbTiO3), PLZT[(Pb,La)(Zr,Ti)O3], or barium titanate (BaTiO3). Piezoelectric layers 17 and 19 may be formed, for example, from a sintered body of ceramic green sheets comprising the aforementioned piezoelectric ceramic materials. In the actual piezoelectric body 11, piezoelectric layers 17 and 19 are integrated to the point that the boundaries between piezoelectric layers are indistinguishable.

[0043] The internal electrode 21, located in region R1, is electrically connected to the external electrode 14 via a connecting conductor 31. The connecting conductor 31 includes a plurality of conductors 34 and a plurality of through-hole conductors 44.

[0044] In region R1, multiple conductors 34 are located in the same layer as their corresponding internal electrodes 25. Each conductor 34 is located within an opening formed on its corresponding internal electrode 25. Viewed from the first direction D1, each opening is formed at a position corresponding to the external electrode 14. Viewed from the first direction D1, each conductor 34 is surrounded by its corresponding internal electrode 25. Each conductor 34 is separated from its corresponding internal electrode 25. Each conductor 34 is opposite to the external electrode 14 in the first direction D1 and is positioned overlapping with the external electrode 14 when viewed from the first direction D1. Each conductor 34 is opposite to its corresponding internal electrode 21 in the first direction D1 and is positioned overlapping with each internal electrode 21 when viewed from the first direction D1.

[0045] In region R2, multiple conductors 34 are located in the same layer as corresponding internal electrodes 23 or internal electrodes 25. The multiple conductors 34 are located within openings formed on the corresponding internal electrodes 23 or internal electrodes 25. Viewed from the first direction D1, each opening is formed at a position corresponding to the external electrode 14. Viewed from the first direction D1, the multiple conductors 34 are surrounded by the corresponding internal electrodes 23 or internal electrodes 25. The multiple conductors 34 are separated from the corresponding internal electrodes 23 or internal electrodes 25. The multiple conductors 34 are opposite to the external electrode 14 in the first direction D1 and are positioned overlapping with the external electrode 14 when viewed from the first direction D1.

[0046] In region R3, conductor 34 is located in the same layer as inner conductor 27. Conductor 34 is located within an opening formed in inner conductor 27. Viewed from the first direction D1, the opening is formed at a position corresponding to outer electrode 14. Viewed from the first direction D1, conductor 34 is surrounded by inner conductor 27. Conductor 34 is separated from inner conductor 27. Conductor 34 is opposite to outer electrode 14 in the first direction D1, and is positioned overlapping with outer electrode 14 when viewed from the first direction D1.

[0047] In region R1, a plurality of via conductors 44 include via conductors 44 located between the external electrode 14 and the conductor 34 adjacent to the external electrode 14, and via conductors 44 located between adjacent internal electrodes 21 and conductors 34. A corresponding via conductor 44 is located between the external electrode 14 and the layer containing the internal electrode 25 closest to the main surface 11a. Other corresponding via conductors 44 are located between the layer containing the internal electrode 25 and the layer containing the internal electrode 21. Viewed from the first direction D1, the plurality of via conductors 44 are respectively disposed at positions overlapping with the external electrode 14 and penetrate the corresponding piezoelectric layer 17 of the plurality of piezoelectric layers 17 along the first direction D1. In region R1, the plurality of via conductors 44 electrically connect the conductor 34 included in region R1 and the internal electrode 21 included in region R1 to the external electrode 14.

[0048] In region R2, a plurality of via conductors 44 include via conductors 44 located between adjacent conductors 34. Corresponding via conductors 44 are located between the layer containing the internal electrode 25 and the layer containing the internal electrode 23. Viewed from the first direction D1, the plurality of via conductors 44 are respectively disposed at positions overlapping with the external electrode 14 and penetrate the corresponding piezoelectric layer 17 of the plurality of piezoelectric layers 17 along the first direction D1. In region R2, the plurality of via conductors 44 electrically connect the conductors 34 contained in region R2.

[0049] In region R3, a plurality of via conductors 44 include via conductors 44 located between adjacent conductors 34. A corresponding via conductor 44 is located between the layer containing the internal electrode 25 closest to region R2 in the internal electrode group 20 and the layer containing the internal conductor 27. Another corresponding via conductor 44 is located between the layer containing the internal electrode 25 closest to region R1 in the internal electrode group 22 and the layer containing the internal conductor 27. Viewed from the first direction D1, the plurality of via conductors 44 are respectively disposed at positions overlapping with the external electrode 14 and penetrate the corresponding piezoelectric layer 19 of the plurality of piezoelectric layers 19 along the first direction D1. In region R3, the plurality of via conductors 44 electrically connect the conductors 34 included in region R3 to the conductors 34 included in regions R1 and R2.

[0050] The internal electrode 23, located in region R2, is electrically connected to the external electrode 13 via a connecting conductor 30. The connecting conductor 30 includes a plurality of conductors 33 and a plurality of through-hole conductors 43.

[0051] In region R1, multiple conductors 33 are located in the same layer as corresponding internal electrodes 21 or 25 of the multiple internal electrodes 21. The multiple conductors 33 are located within openings formed on the corresponding internal electrodes 21 or 25. Viewed from the first direction D1, each opening is formed at a position corresponding to the external electrode 13. Viewed from the first direction D1, the multiple conductors 33 are surrounded by the corresponding internal electrodes 21 or 25. The multiple conductors 33 are separated from the corresponding internal electrodes 23 or 25. The multiple conductors 33 are opposite to the external electrode 13 in the first direction D1 and are positioned overlapping the external electrode 13 when viewed from the first direction D1.

[0052] In region R2, multiple conductors 33 are located in the same layer as their corresponding internal electrodes 25. Each conductor 33 is located within an opening formed on its corresponding internal electrode 25. Viewed from the first direction D1, each opening is formed at a position corresponding to the external electrode 13. Viewed from the first direction D1, each conductor 33 is surrounded by its corresponding internal electrode 25. Each conductor 33 is separated from its corresponding internal electrode 25. Each conductor 33 is opposite to the external electrode 13 in the first direction D1 and is positioned overlapping with the external electrode 13 when viewed from the first direction D1. Each conductor 33 is opposite to its corresponding internal electrode 23 in the first direction D1 and is positioned overlapping with each internal electrode 23 when viewed from the first direction D1.

[0053] In region R3, conductor 33 is located in the same layer as inner conductor 27. Conductor 33 is located within an opening formed in inner conductor 27. Viewed from the first direction D1, the opening is formed at a position corresponding to outer electrode 13. Viewed from the first direction D1, conductor 33 is surrounded by inner conductor 27. Conductor 33 is separated from inner conductor 27. Conductor 33 is opposite to outer electrode 13 in the first direction D1 and is positioned overlapping with outer electrode 13 when viewed from the first direction D1. For example, conductors 33 and 34, located in the same layer as inner conductor 27, are located within the same opening. Conductors 33 and 34, located in the same layer as inner conductor 27, are adjacent to each other within the same opening. In each of regions R1 and R2, for example, conductors 33 and 34, located in the same layer as inner electrode 25, are located within the same opening. Conductors 33 and 34, located in the same layer as inner electrode 25, are adjacent to each other within the same opening.

[0054] In region R1, the plurality of via conductors 43 include via conductors 43 located between the external electrode 13 and the conductor 33 adjacent to the external electrode 13, and via conductors 43 located between adjacent conductors 33. A corresponding via conductor 43 is located between the external electrode 13 and the layer containing the internal electrode 25 closest to the main surface 11a. Other corresponding via conductors 43 are located between the layer containing the internal electrode 25 and the layer containing the internal electrode 21. Viewed from the first direction D1, the plurality of via conductors 43 are respectively disposed at positions overlapping with the external electrode 13 and penetrate the corresponding piezoelectric layer 17 of the plurality of piezoelectric layers 17 along the first direction D1. In region R1, the plurality of via conductors 43 electrically connect the conductors 33 contained in region R1 to the external electrode 13.

[0055] In region R2, a plurality of via conductors 43 include via conductors 43 located between adjacent internal electrodes 23 and conductors 33. Corresponding via conductors 43 are located between layers containing internal electrodes 25 and layers containing internal electrodes 23. Viewed from the first direction D1, the plurality of via conductors 43 are respectively disposed at positions overlapping with external electrodes 13 and penetrate corresponding piezoelectric layers 17 along the first direction D1. In region R2, the plurality of via conductors 43 electrically connect the conductors 33 included in region R2 to the internal electrodes 23 included in region R2.

[0056] In region R3, a plurality of via conductors 43 include via conductors 43 located between adjacent conductors 33. A corresponding via conductor 43 is located between the layer containing the internal electrode 25 closest to region R2 in the internal electrode group 20 and the layer containing the internal conductor 27. Another corresponding via conductor 43 is located between the layer containing the internal electrode 25 closest to region R1 in the internal electrode group 22 and the layer containing the internal conductor 27. Viewed from the first direction D1, the plurality of via conductors 43 are respectively disposed at positions overlapping with the external electrode 13 and penetrate the corresponding piezoelectric layer 19 in the plurality of piezoelectric layers 19 along the first direction D1. In region R3, the plurality of via conductors 43 electrically connect the conductors 33 included in region R3 to the conductors 33 included in regions R1 and R2.

[0057] The internal electrodes 25 disposed in regions R1 and R2 are electrically connected to the external electrodes 15 via connecting conductors 32. The connecting conductors 32 include a plurality of conductors 35 and a plurality of through-hole conductors 45.

[0058] Multiple conductors 35 are located in the same layer as the corresponding internal electrode 21 or the corresponding internal electrode 23 among the multiple internal electrodes 21. The multiple conductors 35 are located within openings formed on the corresponding internal electrode 21 or the corresponding internal electrode 23. Viewed from the first direction D1, each opening is formed at a position corresponding to the external electrode 15. Viewed from the first direction D1, the multiple conductors 35 are surrounded by the corresponding internal electrode 21 or the corresponding internal electrode 23. The multiple conductors 35 are separated from the corresponding internal electrode 21 or the corresponding internal electrode 23. The multiple conductors 35 are opposite to the external electrode 15 in the first direction D1 and are positioned overlapping with the external electrode 15 when viewed from the first direction D1. The multiple conductors 35 are opposite to the corresponding internal electrode 25 among the multiple internal electrodes 25 in the first direction D1 and are positioned overlapping with the internal electrode 25 when viewed from the first direction D1.

[0059] In region R1, multiple conductors 35 are located in the same layer as their corresponding internal electrodes 21. The multiple conductors 35 are located within openings formed on their respective internal electrodes 21. Viewed from the first direction D1, each opening is formed at a position corresponding to the external electrode 15. Viewed from the first direction D1, the multiple conductors 35 are each surrounded by their corresponding internal electrodes 21. The multiple conductors 35 are separated from their respective internal electrodes 21. The multiple conductors 35 are respectively opposite to the external electrode 15 in the first direction D1, and are positioned overlapping with the external electrode 15 when viewed from the first direction D1.

[0060] In region R2, multiple conductors 35 are located in the same layer as their corresponding internal electrodes 23. Each conductor 35 is located within an opening formed on its corresponding internal electrode 23. Viewed from the first direction D1, each opening is formed at a position corresponding to the external electrode 15. Viewed from the first direction D1, each conductor 35 is surrounded by its corresponding internal electrode 23. Each conductor 35 is separated from its corresponding internal electrode 23. Each conductor 35 is opposite to the external electrode 15 in the first direction D1, and is positioned overlapping with the external electrode 15 when viewed from the first direction D1. Each conductor 35 is opposite to its corresponding internal electrode 25 in the first direction D1, and is positioned overlapping with its corresponding internal electrode 25 when viewed from the first direction D1.

[0061] In region R3, conductor 35 is located in the same layer as inner conductor 27. Conductor 35 is located within an opening formed in inner conductor 27. Viewed from the first direction D1, the opening is formed at a position corresponding to outer electrode 15. Viewed from the first direction D1, conductor 35 is surrounded by inner conductor 27. Conductor 35 is separated from inner conductor 27. Conductor 35 is opposite to outer electrode 15 in the first direction D1, and is positioned overlapping with outer electrode 15 when viewed from the first direction D1.

[0062] In region R1, a plurality of via conductors 45 include via conductors 45 located between an external electrode 15 and an internal electrode 25 adjacent to the external electrode 15, and via conductors 45 located between adjacent internal electrodes 25 and conductors 35. A corresponding via conductor 45 is located between the external electrode 15 and the layer containing the internal electrode 25 closest to the main surface 11a. Other corresponding via conductors 43 are located between the layer containing the internal electrode 25 and the layer containing the internal electrode 21. Viewed from the first direction D1, the plurality of via conductors 45 are respectively disposed at positions overlapping with the external electrode 15 and penetrate the corresponding piezoelectric layer 17 of the plurality of piezoelectric layers 17 along the first direction D1. In region R1, the plurality of via conductors 45 electrically connect the conductors 35 and the internal electrodes 25 contained in region R1 to the external electrode 15.

[0063] In region R2, a plurality of via conductors 45 include via conductors 45 located between adjacent internal electrodes 25 and conductors 35. Corresponding via conductors 45 are located between the layer containing the internal electrode 25 and the layer containing the internal electrode 23. Viewed from the first direction D1, the plurality of via conductors 45 are respectively disposed at positions overlapping with the external electrode 15 and penetrate the corresponding piezoelectric layer 17 of the plurality of piezoelectric layers 17 along the first direction D1. In region R2, the plurality of via conductors 45 electrically connect the conductor 35 included in region R2 to the internal electrode 25 included in region R2.

[0064] In region R3, the plurality of via conductors 45 include: a via conductor 45 located between the internal electrode 25 and conductor 35 closest to region R2 in the internal electrode group 20, and a via conductor 45 located between the internal electrode 25 and conductor 35 closest to region R1 in the internal electrode group 22. A corresponding via conductor 45 is located between the layer containing the internal electrode 25 closest to region R2 in the internal electrode group 20 and the layer containing the internal conductor 27. Another corresponding via conductor 45 is located between the layer containing the internal electrode 25 closest to region R1 in the internal electrode group 22 and the layer containing the internal conductor 27. Viewed from the first direction D1, the plurality of via conductors 45 are respectively disposed at positions overlapping with the external electrode 15 and penetrate the corresponding piezoelectric layer 19 of the plurality of piezoelectric layers 19 along the first direction D1. In region R3, the plurality of via conductors 45 electrically connect the conductor 35 contained in region R3 and the internal electrode 25 contained in regions R1 and R2.

[0065] Viewed from the first direction D1, conductors 33, 34, and 35 included in connecting conductors 30, 31, and 32 are rectangular in shape. For example, conductors 33, 34, and 35 are rectangular with rounded corners. Conductors 33, 34, and 35 included in connecting conductors 30, 31, and 32 can also be square in shape.

[0066] Connecting conductors 30, 31, and 32 comprise a conductive material. The conductive material may include, for example, Ag, Pd, Pt, or an Ag-Pd alloy. Connecting conductors 30, 31, and 32 may be configured as a sintered body containing a conductive paste comprising the aforementioned conductive material. Through-hole conductors 43, 44, and 45 are formed by sintering conductive paste filling through-holes formed in the ceramic green sheet used to form the corresponding piezoelectric layers 17 and 19. Internal electrodes 21, 23, and 25 may also comprise the aforementioned conductive material. Internal electrodes 21, 23, and 25 may be configured as a sintered body containing a conductive paste comprising the aforementioned conductive material.

[0067] Region R1 includes the area between multiple internal electrodes 21 and 25 that are opposite to each other. Region R2 includes the area between multiple internal electrodes 23 and 25 that are opposite to each other. Hereinafter, the area between multiple internal electrodes that are opposite to each other will sometimes be referred to as the "inter-electrode region".

[0068] The inter-electrode region included in region R1 comprises a region within the plurality of piezoelectric layers 17 contained in region R1, sandwiched between opposing inner electrodes 21 and 25. The inter-electrode region included in region R1 contains piezoelectrically active regions. The inter-electrode region included in region R2 comprises a region within the plurality of piezoelectric layers 17 contained in region R2, sandwiched between opposing inner electrodes 23 and 25. The inter-electrode region included in region R2 contains piezoelectrically active regions.

[0069] The active regions contained in region R1 and region R2 are located between main surfaces 11a and 11b. Both active regions are composed of at least one piezoelectric layer 17. The active region in region R1 is located closer to main surface 11a than the active region in region R2. The active region in region R2 is located closer to main surface 11b than the active region in region R1. Region R3 is located between the active regions in regions R1 and R2. For example, region R3 contains a piezoelectrically inert region.

[0070] For example, viewed from the first direction D1, the active regions contained in regions R1 and R2 are positioned in a manner that surrounds the plurality of external electrodes 13, 14, and 15. The active regions contained in regions R1 and R2 include: the region located between external electrodes 14 and 15 when viewed from the first direction D1, and the region outside the region where external electrodes 13, 14, and 15 are located when viewed from the first direction D1.

[0071] When the piezoelectric element 10 is activated, voltages of different polarities are applied to external electrodes 13 and 14. No voltage is applied to external electrode 15 as is applied to external electrodes 13 and 14. External electrode 15 includes a ground electrode.

[0072] When a voltage is applied to the external electrode 14, an electric field is generated between the internal electrode 21 and the corresponding internal electrode 25. An electric field is generated in region R1, and the active region contained in region R1 is displaced according to this electric field. When a voltage is applied to the external electrode 13, an electric field is generated between the internal electrode 23 and the corresponding internal electrode 25. An electric field is generated in region R2, and the active region contained in region R2 is displaced according to this electric field. Regions R1 and R2, for example, are displaced in opposite directions. When regions R1 and R2 are displaced in opposite directions, the active regions contained in region R1 and region R2 are displaced in opposite directions along the first direction D1. When a voltage is applied to the external electrodes 13 and 14, flexure occurs in the piezoelectric element 10.

[0073] Reference Figure 1The structure of the vibrating component 50 will be described below. The vibrating component 50 is bonded to the main surface 11b of the piezoelectric element 11. The vibrating component 50 includes main surfaces 50a and 50b that are opposite each other. The piezoelectric element 10 is disposed on the main surface 50a. For example, the vibrating component 50 includes a plate-shaped component. The vibrating component 50 may contain, for example, metal. The vibrating component 50 may contain, for example, a Ni-Fe alloy, glass, resin, or stainless steel. Viewed from the first direction D1, the vibrating component 50 is rectangular. The rectangular shape includes a shape in which the corners are chamfered or rounded.

[0074] The length of the vibrating component 50 in the first direction D1 is, for example, 0.1 to 2 mm. The length of the vibrating component 50 in the second direction D2 is, for example, 10 to 75 mm. The length of the vibrating component 50 in the third direction D3 is, for example, 10 to 75 mm. In the vibrating component 50, for example, the second direction D2 is the length direction.

[0075] The vibrating element 50 is bonded to the piezoelectric element 10, for example, through a resin layer. The main surface 11b of the piezoelectric element 11 and the main surface 50a of the vibrating element 50 face each other. The resin layer is located between the main surface 11b and the main surface 50a. The main surface 11b and the main surface 50a are bonded through the resin layer. In the configuration where the piezoelectric element 10 and the vibrating element 50 are bonded, the main surfaces 50a and 50b face each other in a first direction D1. Viewed from the first direction D1, the piezoelectric element 10 is, for example, disposed in the central region of the main surface 50a. The resin layer, for example, contains epoxy resin or acrylic resin. The resin layer, for example, does not contain conductive fillers and has electrical insulating properties.

[0076] When an AC voltage is applied to the external electrodes 13 and 14, the active regions contained in region R1 and region R2 of the piezoelectric element 10 repeatedly expand and contract according to the frequency of the applied AC voltage. The active regions in region R1 and region R2 expand and contract in opposite directions, causing the piezoelectric element 10 to flexurally vibrate. In the vibrating member 50, flexural vibration is generated integrally with the piezoelectric element 10 based on its flexural vibration.

[0077] Next, the structure of the wiring component 60 will be described. The wiring component 60 electrically connects the piezoelectric element 10 to the electronic device. The wiring component 60 includes a pair of ends, one of which is engaged with the piezoelectric element 10. The wiring component 60 includes a substrate 61 and a reinforcing member 62. A plurality of conductors are disposed on the substrate 61, each conductor being electrically connected at one end to the external electrodes 13, 14, 15 of the piezoelectric element 10. The wiring component 60 may include, for example, a flexible printed circuit board (FPC) or a flexible flat cable (FFC). The wiring component 60 is plate-shaped, sheet-shaped, or strip-shaped. The other end of the pair of ends is engaged with the reinforcing member 62. In the wiring component 60, the other end is located on the side opposite to one end. The reinforcing member 62 includes a plate-shaped component with electrical insulation. The reinforcing member 62 may contain, for example, polyimide resin. The electronic device may include, for example, a circuit board or electronic components.

[0078] Reference Figure 6 and Figure 7 The piezoelectric element 10 of the modified embodiment described above will be described. Figure 6 This is a diagram showing the cross-sectional structure of the piezoelectric element in this modified example. Figure 7 This is an exploded perspective view of the piezoelectric element in this modified example.

[0079] The piezoelectric element 10 in this modified example is generally similar to or the same as the piezoelectric element 10 in the above-described embodiment, but the structure of the piezoelectric element 10 in this modified example with respect to region R3 is different from that of the piezoelectric element 10 in the above-described embodiment. Hereinafter, the differences between this modified example and the above-described embodiment will be mainly explained. Figure 7 This indicates the structure of region R3.

[0080] Region R1 in this variation has the same structure as region R1 in the above embodiment. That is, region R1 in this variation may also include Figure 3 The structure shown is illustrated. Region R2 in this variation has the same structure as region R2 in the above embodiment. That is, region R2 in this variation may also include... Figure 4 The structure shown is different from that in the above-described embodiment in terms of region R3, for example, it includes four piezoelectric layers 19.

[0081] Internal electrode group 20 includes multiple internal electrodes 21 and 25. The multiple internal electrodes 21 and 25 are opposite to each other with a gap L1, separated by a corresponding piezoelectric layer 17. Internal electrode group 22 includes multiple internal electrodes 23 and 25. The multiple internal electrodes 23 and 25 are opposite to each other with a gap L2, separated by a corresponding piezoelectric layer 17.

[0082] Region R3 is located between the internal electrode 25 closest to region R2 in internal electrode group 20 and the internal electrode 25 closest to region R1 in internal electrode group 22. Region R3 includes multiple piezoelectric layers 19. Region R3 includes, for example, four piezoelectric layers 19. The piezoelectric layers 19 are located between the piezoelectric layers 17 included in region R1 and the piezoelectric layers 17 included in region R2. In the piezoelectric body 11, the multiple piezoelectric layers 17, 19 are stacked on the first direction D1. The thickness of each piezoelectric layer 19 is the same.

[0083] In this variation, the piezoelectric element 10 includes a plurality of internal conductors 27 in region R3. Unlike the embodiments described above, the piezoelectric element 10 includes two internal conductors 27. The piezoelectric element 10 includes an internal electrode 25 disposed between the two internal conductors 27. The two internal conductors 27 and the internal electrode 25 disposed between them are located between the internal electrode 25 closest to region R2 in internal electrode group 20 and the internal electrode 25 closest to region R1 in internal electrode group 22. The two internal conductors 27 are disposed in region R3. The internal electrode 25 closest to region R2 and the internal electrode 25 closest to region R1 are separated by a distance L3 in the first direction D1. In this variation, the distance L3 is greater than the distances L1 and L2. The two internal conductors 27 are not electrically connected to the plurality of internal electrodes 21, 25 included in internal electrode group 20 and the plurality of internal electrodes 23, 25 included in internal electrode group 22. The two internal conductors 27 and the internal electrode 25 disposed between the two internal conductors 27 are not exposed on the sides 11c and 11e. The two internal conductors 27 and the internal electrode 25 disposed between the two internal conductors 27 are separated from the sides 11c and 11e.

[0084] In region R3, the piezoelectric element 10 may also omit the two internal conductors 27. In the structure where the piezoelectric element 10 does not include the two internal conductors 27, the spacing L3 is greater than the spacings L1 and L2. In region R3, the piezoelectric element 10 may also omit the two internal conductors 27 but include internal electrodes 25. In the structure where the piezoelectric element 10 omits the two internal conductors 27 but includes internal electrodes 25, the spacing L3 is greater than the spacings L1 and L2.

[0085] As explained above, in the piezoelectric element 10, the internal electrode group 20 includes a plurality of internal electrodes 21, 25 facing each other within region R1, and region R1 includes an inter-electrode region. The internal electrode group 22 includes a plurality of internal electrodes 23, 25 facing each other within region R2, and region R2 includes an inter-electrode region. When a voltage is applied, an electric field is generated in the inter-electrode regions contained in each of regions R1 and R2, and the inter-electrode regions contained in each of regions R1 and R2 may be displaced. In the piezoelectric element 10, the internal electrode 25 closest to region R2 is electrically connected to the internal electrode 25 closest to region R1. Therefore, when a voltage is applied, it is difficult to generate an electric field in the region R3 located between the internal electrode 25 closest to region R2 and the internal electrode 25 closest to region R1, i.e., region R3, and region R3 is difficult to displace. In the event of displacement of the inter-electrode regions contained in each of regions R1 and R2, region R3 alleviates the stress acting on region R2 due to the displacement in region R1, and alleviates the stress acting on region R1 due to the displacement in region R2. The piezoelectric element 10 can mitigate the stress acting on the piezoelectric element 11.

[0086] In the piezoelectric element 10, the internal electrode group 20 includes a plurality of internal electrodes 21, 25, including an internal electrode 21 and an internal electrode 25 opposite to the internal electrode 21. The internal electrode group 22 includes a plurality of internal electrodes 23, 25, including: an internal electrode 23 that is not electrically connected to the internal electrodes 21 and 25; and an internal electrode 25 that is opposite to the internal electrode 23 and electrically connected to the internal electrode 25 included in the internal electrode group 20. The internal electrode closest to region R2 includes internal electrode 25, and the internal electrode closest to region R1 includes internal electrode 25.

[0087] In the piezoelectric element 10, the internal electrode group 20 includes an internal electrode 21 and an internal electrode 25 opposite to the internal electrode 21, and the internal electrode group 22 includes an internal electrode 23 not electrically connected to the internal electrodes 21 and 25, and an internal electrode 25 opposite to the internal electrode 23. The internal electrode 25 closest to region R2 is electrically connected to the internal electrode 25 closest to region R1. Therefore, even with the structure that the internal electrode closest to region R2 includes the internal electrode 25 opposite to the internal electrode 21, and the internal electrode closest to region R1 includes the internal electrode 25 opposite to the internal electrode 23, it is difficult to generate an electric field in region R3 when a voltage is applied, and region R3 is difficult to displace. Region R3 alleviates the stress acting on region R2 due to displacement in region R1, and alleviates the stress acting on region R1 due to displacement in region R2. As a result, the piezoelectric element 10 can reliably alleviate the stress acting within the piezoelectric element 11.

[0088] The piezoelectric element 10 includes an internal conductor 27. The internal conductor 27 is disposed between the internal electrode 25 closest to region R2 and the internal electrode 25 closest to region R1, and is not electrically connected to the plurality of internal electrodes 21, 25 included in the internal electrode group 20 and the plurality of internal electrodes 23, 25 included in the internal electrode group 22.

[0089] The internal conductor 27 is positioned between the internal electrode 25 closest to region R2 and the internal electrode 25 closest to region R1, i.e., region R3, and is not electrically connected to the plurality of internal electrodes 21, 23, 25. Therefore, when a voltage is applied, it is more difficult to generate an electric field in region R3, and region R3 is less likely to displace. Region R3 further mitigates the stress acting on region R2 due to displacement in region R1, and further mitigates the stress acting on region R1 due to displacement in region R2. As a result, the piezoelectric element 10 can more reliably mitigate the stress acting within the piezoelectric body 11.

[0090] In the piezoelectric element 10, the internal conductor 27 is not exposed on the sides 11c and 11e.

[0091] In the piezoelectric element 10, the internal conductor 27 is covered by the piezoelectric element 11 and disposed within the piezoelectric element 11. Therefore, electrical short circuits are less likely to occur in the piezoelectric element 10.

[0092] In the piezoelectric element 10, the interval L3 is greater than the intervals L1 and L2.

[0093] In the piezoelectric element 10, the distance between region R1 and region R2 is reliably large. Corresponding to the large distance between region R1 and region R2, the stress acting on region R2 due to displacement in region R1 and the stress acting on region R1 due to displacement in region R2 are attenuated. Therefore, the piezoelectric element 10 can more reliably mitigate the stress acting within the piezoelectric element 11.

[0094] In the piezoelectric element 10, the multiple internal electrodes 21, 25 included in the internal electrode group 20 and the multiple internal electrodes 23, 25 included in the internal electrode group 22 are not exposed on the sides 11c, 11e.

[0095] In the piezoelectric element 10, multiple internal electrodes 21, 23, and 25 are covered by a piezoelectric element 11 and disposed within the piezoelectric element 11. Therefore, electrical short circuits are less likely to occur in the piezoelectric element 10.

[0096] In the piezoelectric element 10, regions R1 and R2 are displaced in opposite directions.

[0097] The piezoelectric element 10 includes a plurality of external electrodes 13, 14, 15, which are disposed on the main surface 11a and are electrically connected to the corresponding internal electrodes 21, 23, 25 of the plurality of internal electrodes 21, 25 included in the internal electrode group 20 and the plurality of internal electrodes 23, 25 included in the internal electrode group 22.

[0098] Reference Figure 8 The structure of another embodiment of the piezoelectric element 10 will be described. Figure 8 This is a diagram showing the cross-sectional structure of a piezoelectric element according to another embodiment.

[0099] Another embodiment of the piezoelectric element 10 is generally similar to or the same as the piezoelectric element 10 of the above-described embodiment, but the piezoelectric element 10 of the other embodiment differs from the piezoelectric element 10 of the above-described embodiment in terms of the structure between region R1 and region R3 and the structure between region R3 and region R2. Hereinafter, the differences between the piezoelectric element 10 of the other embodiment and the piezoelectric element 10 of the above-described embodiment will be mainly described.

[0100] Another embodiment of the piezoelectric element 10 includes an internal electrode group 20 and an internal electrode group 22.

[0101] An internal electrode group 20 is disposed in region R1. The internal electrode group 20 includes a plurality of internal electrodes 21 and 25. Internal electrodes 25 are opposite to internal electrodes 21. For example, the internal electrode group 20 includes four internal electrodes 21 and four internal electrodes 25. The internal electrodes 21 and 25 are arranged alternately, and are opposite to each other at a distance L1, separated by a corresponding piezoelectric layer 17 from a plurality of piezoelectric layers 17. The distance L1 between internal electrodes 21 and 25 is the same. The internal electrode group 20 includes the internal electrode 21 closest to region R2 and the internal electrode 25 closest to the main surface 11a among the plurality of internal electrodes 21 and 25.

[0102] An internal electrode group 22 is disposed in region R2. The internal electrode group 22 includes a plurality of internal electrodes 23 and 25. Internal electrodes 23 are not electrically connected to the plurality of internal electrodes 21 and 25 included in the internal electrode group 20. Internal electrodes 25 are opposite to internal electrodes 23. The internal electrodes 25 included in the internal electrode group 22 are electrically connected to the internal electrodes 25 included in the internal electrode group 20. The internal electrode group 22, for example, includes four internal electrodes 23 and four internal electrodes 25. In the internal electrode group 22, the internal electrodes 23 and 25 are arranged alternately, and are opposite to each other at a distance L2, separated by a corresponding piezoelectric layer 17 from a plurality of piezoelectric layers 17. The distance L2 between internal electrodes 23 and internal electrodes 25 is the same.

[0103] The internal electrode group 22 includes the internal electrode 23 closest to region R1 among the plurality of internal electrodes 23, 25 contained in the internal electrode group 22. The internal electrode 23 closest to region R1 and the internal electrode 21 closest to region R2 are not electrically connected to each other. The internal electrode group 22 includes the internal electrode 25 closest to the main surface 11b among the plurality of internal electrodes 23, 25 contained in the internal electrode group 22.

[0104] Region R3 is located between the internal electrode 21 closest to region R2 in internal electrode group 20 and the internal electrode 23 closest to region R1 in internal electrode group 22. Region R3 includes multiple piezoelectric layers 19. Region R3 includes, for example, three piezoelectric layers 19. The piezoelectric layers 19 are located between the piezoelectric layers 17 included in region R1 and the piezoelectric layers 17 included in region R2. In the piezoelectric body 11, the multiple piezoelectric layers 17, 19 are stacked on the first direction D1. The thickness of each piezoelectric layer 19 is the same.

[0105] Another embodiment of the piezoelectric element 10 includes a plurality of internal conductors 27. The plurality of internal conductors 27 are disposed in region R3. The piezoelectric element 10, for example, includes two internal conductors 27. The two internal conductors 27 are opposite each other and disposed between the internal electrode 21 closest to region R2 and the internal electrode 23 closest to region R1. The two internal conductors 27 are disposed in region R3. The internal electrode 21 closest to region R2 and the internal electrode 23 closest to region R1 are spaced apart by a distance L3 in a first direction D1. The distance L3 is greater than the distances L1 and L2. The two internal conductors 27 are not electrically connected to the plurality of internal electrodes 21, 25 included in internal electrode group 20 and the plurality of internal electrodes 23, 25 included in internal electrode group 22. The two internal conductors 27 are not exposed on sides 11c, 11e. Another embodiment of the piezoelectric element 10 may also include a single internal conductor 27. In the configuration where the piezoelectric element 10 includes a single internal conductor 27, the distance L3 is greater than the distances L1 and L2.

[0106] As described above, another embodiment of the piezoelectric element 10 includes a piezoelectric body 11, an internal electrode group 20, an internal electrode group 22, and an internal conductor 27. The piezoelectric body 11 includes main surfaces 11a and 11b facing each other and side surfaces 11c and 11e connecting the main surfaces 11a and 11b, and includes a region R1 containing the main surface 11a and a region R2 containing the main surface 11b. The internal electrode group 20 is disposed in region R1 and includes a plurality of internal electrodes 21 and 25 facing each other in the opposite direction of the main surfaces 11a and 11b. The internal electrode group 22 is disposed in region R2 and includes a plurality of internal electrodes 23 and 25 facing each other in the opposite direction of the main surfaces 11a and 11b. The internal conductor 27 is disposed between the internal electrode 21 in the closest region R2 of the plurality of internal electrodes 21, 25 included in the internal electrode group 20 and the internal electrode 23 in the closest region R1 of the plurality of internal electrodes 23, 25 included in the internal electrode group 22, and is not electrically connected to the plurality of internal electrodes 21, 25 included in the internal electrode group 20 and the plurality of internal electrodes 23, 25 included in the internal electrode group 22.

[0107] In another embodiment of the piezoelectric element 10, the piezoelectric element 11 includes a region R3 located between the inner electrode 21 closest to region R2 among the plurality of inner electrodes 21, 25 included in the inner electrode group 20 and the inner electrode 23 closest to region R1 among the plurality of inner electrodes 23, 25 included in the inner electrode group 22. An inner conductor 27 is disposed in region R3 and is not electrically connected to the plurality of inner electrodes 21, 25 included in the inner electrode group 20 or the plurality of inner electrodes 23, 25 included in the inner electrode group 22. Therefore, when a voltage is applied, it is difficult to generate an electric field in region R3. Region R3 is difficult to displace. Region R3 alleviates the stress acting on region R2 due to displacement in region R1, and alleviates the stress acting on region R1 due to displacement in region R2. The piezoelectric element 10 is able to alleviate the stress acting within the piezoelectric element 11.

[0108] The embodiments and variations of the present invention have been described above, but the present invention is not necessarily limited to the embodiments and variations described above, and various changes can be made without departing from its spirit.

[0109] The internal conductor 27 may also be exposed on either side 11c or 11e. However, in a structure in which the internal conductor 27 is not exposed on side 11c or 11e, as described above, it is difficult to generate an electrical short circuit.

[0110] The interval L3 can also be smaller than the intervals L1 and L2. However, as mentioned above, a structure with an interval L3 larger than the intervals L1 and L2 can more reliably mitigate the stress acting within the piezoelectric element 11.

[0111] Multiple internal electrodes 21, 23, and 25 may also be exposed on any of the sides 11c and 11e. However, in a structure in which the internal electrodes 21, 23, and 25 are not exposed on the sides 11c and 11e, as described above, it is difficult to generate an electrical short circuit.

Claims

1. A piezoelectric element, wherein, have: The piezoelectric element includes a first main surface and a second main surface opposite to each other, and a side surface connecting the first main surface and the second main surface, and includes a first region containing the first main surface and a second region containing the second main surface. A first internal electrode group is disposed in the first region and includes a plurality of internal electrodes facing each other in a direction opposite to the first main surface and the second main surface; and A second internal electrode group is disposed in the second region and includes a plurality of internal electrodes facing each other in the direction opposite to the first main surface and the second main surface. The internal electrode closest to the second region among the plurality of internal electrodes included in the first internal electrode group is electrically connected to the internal electrode closest to the first region among the plurality of internal electrodes included in the second internal electrode group.

2. The piezoelectric element as claimed in claim 1, wherein, The plurality of internal electrodes included in the first internal electrode group include: First internal electrode; and The second internal electrode is opposite to the first internal electrode. The plurality of internal electrodes included in the second internal electrode group include: A third internal electrode that is not electrically connected to the first internal electrode and the second internal electrode; and A fourth internal electrode that is opposite to the third internal electrode and electrically connected to the second internal electrode. The internal electrode closest to the second region includes the second internal electrode. The internal electrode closest to the first region includes the fourth internal electrode.

3. The piezoelectric element as described in claim 1 or 2, wherein, It also includes: an internal conductor disposed between the internal electrode closest to the second region and the internal electrode closest to the first region, and not electrically connected to the plurality of internal electrodes included in the first internal electrode group and the plurality of internal electrodes included in the second internal electrode group.

4. The piezoelectric element as described in claim 3, wherein, The internal conductor is not exposed on the side.

5. A piezoelectric element, wherein, have: The piezoelectric element includes a first main surface and a second main surface opposite to each other, and a side surface connecting the first main surface and the second main surface, and includes a first region containing the first main surface and a second region containing the second main surface. A first internal electrode group is disposed in the first region and includes a plurality of internal electrodes facing each other in the direction opposite to the first main surface and the second main surface; A second internal electrode group is disposed in the second region and includes a plurality of internal electrodes facing each other in the direction opposite to the first main surface and the second main surface; and An internal conductor is disposed between the internal electrode closest to the second region among the plurality of internal electrodes included in the first internal electrode group and the internal electrode closest to the first region among the plurality of internal electrodes included in the second internal electrode group, and is not electrically connected to the plurality of internal electrodes included in the first internal electrode group and the plurality of internal electrodes included in the second internal electrode group.

6. The piezoelectric element as claimed in claim 5, wherein, The internal conductor is not exposed on the side.

7. The piezoelectric element according to any one of claims 1 to 6, wherein, The spacing between the internal electrode closest to the second region and the internal electrode closest to the first region is greater than the spacing between the plurality of internal electrodes included in the first internal electrode group and the spacing between the plurality of internal electrodes included in the second internal electrode group.

8. The piezoelectric element according to any one of claims 1 to 7, wherein, The plurality of internal electrodes contained in the first internal electrode group and the plurality of internal electrodes contained in the second internal electrode group are not exposed on the side.

9. The piezoelectric element according to any one of claims 1 to 8, wherein, The first region and the second region are displaced in opposite directions.

10. The piezoelectric element according to any one of claims 1 to 9, wherein, It also includes: a plurality of external electrodes disposed on the first main surface and electrically connected to corresponding internal electrodes among the plurality of internal electrodes included in the first internal electrode group and the plurality of internal electrodes included in the second internal electrode group.

Images