Piezoelectric element

Abstract

To provide a piezoelectric element that suppresses deterioration of displacement characteristics.SOLUTION: A piezoelectric element PD1 includes a piezoelectric element body 1, electrodes 11 and 13 arranged on the piezoelectric element body 1, and electrodes 21 and 22 arranged on the piezoelectric element body 1 and electrically connected to the electrodes 11 and 13. The electrode 21, 22 includes an electrode area E1 that is physically connected to the electrodes 11 and 13 and covers an element body area B1 of the piezoelectric element body 1, and an electrode area E2 of the piezoelectric element body 1 covers an element body area B2 different from the element body area B1. The ratio of the electrode area E1 covering the element body area B1 is greater than the ratio of the electrode area E2 covering the element body area B2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a piezoelectric element. [Background technology]

[0002] A known piezoelectric element includes a piezoelectric element and a plurality of electrodes arranged on the piezoelectric element so as to face each other (see, for example, Patent Document 1). The plurality of electrodes includes, for example, a plurality of first electrodes arranged on the piezoelectric element and a plurality of second electrodes arranged on the piezoelectric element so as to face each other and electrically connected to corresponding first electrodes among the plurality of first electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2019-114959 Summary of the Invention [Problem to be solved by the invention]

[0004] The electrodes have electrical resistance. Therefore, when driving power is supplied to the piezoelectric element, the electrodes tend to generate heat. The heat generated in the electrodes can be transferred to the piezoelectric element. When the heat generated in the electrodes is transferred to the piezoelectric element, the piezoelectric element tends to depolarize. When the piezoelectric element is depolarized, the displacement characteristics of the piezoelectric element deteriorate.

[0005] An object of one aspect of the present invention is to provide a piezoelectric element that suppresses deterioration of displacement characteristics. [Means for solving the problem]

[0006] The present inventors have conducted research into piezoelectric elements that suppress deterioration of displacement characteristics, and as a result, have newly obtained the following findings, which have led to the present invention.

[0007] In a configuration in which the electrode has a first electrode and a second electrode, the second electrode is, for example, physically connected to the corresponding first electrode and has a first electrode region covering a first body region of the piezoelectric body and a second electrode region covering a second body region of the piezoelectric body that is different from the first body region. The second electrode tends to generate more heat than the first electrode. In a configuration in which the second electrode has a first electrode region and a second electrode region, the first electrode region tends to generate more heat than the second electrode region.

[0008] Heat generation in the second electrode is affected by the proportion of the second electrode that covers the piezoelectric element. In a configuration in which the second electrode covers a large proportion of the piezoelectric element, the second electrode is less likely to generate heat than in a configuration in which the second electrode covers a small proportion of the piezoelectric element. However, in a configuration in which the second electrode covers a large proportion of the piezoelectric element, the second electrode may inhibit the displacement of the piezoelectric element compared to a configuration in which the second electrode covers a small proportion of the element. If the second electrode inhibits the displacement of the piezoelectric element, the displacement characteristics of the piezoelectric element will deteriorate.

[0009] The first electrode region covers the first element body region. The second electrode region covers a second element body region that is different from the first element body region. In a configuration in which the proportion of the first electrode region covering the first element body region is greater than the proportion of the second electrode region covering the second element body region, the second electrode is less likely to generate heat than in a configuration in which the proportion of the second electrode region covering the piezoelectric element body is small, because the proportion of the first electrode region covering the first element body region is larger. In a configuration in which the proportion of the second electrode region covering the second element body region is smaller than the proportion of the first electrode region covering the first element body region, the second electrode is less likely to inhibit displacement of the piezoelectric element body, because the proportion of the second electrode region covering the second element body region is smaller, because the proportion of the second electrode region covering the second element body region is smaller, because the proportion of the second electrode region covering the piezoelectric element body is large,

[0010] A piezoelectric element according to one aspect of the present invention comprises a piezoelectric body, a first electrode disposed on the piezoelectric body, and a second electrode disposed on the piezoelectric body and electrically connected to the first electrode. The second electrode is physically connected to the first electrode and has a first electrode region covering a first body region of the piezoelectric body, and a second electrode region covering a second body region of the piezoelectric body that is different from the first body region. The proportion of the first electrode region covering the first body region is greater than the proportion of the second electrode region covering the second body region.

[0011] According to the above aspect, the proportion of the first electrode region covering the first element body region is greater than the proportion of the second electrode region covering the second element body region. Therefore, the second electrode is less likely to generate heat and less likely to inhibit the displacement of the piezoelectric element. As a result, the above aspect suppresses deterioration of the displacement characteristics.

[0012] In the above aspect, the second electrode may have a first electrode region and a second electrode region. In a configuration in which the second electrode has a first electrode region and a second electrode region, the second electrode is less likely to generate heat and less likely to inhibit the displacement of the piezoelectric element, thereby further suppressing deterioration of the displacement characteristics.

[0013] In the above aspect, the area of ​​the first electrode region may be smaller than the area of ​​the second electrode region. The first electrode region tends to hinder the displacement of the piezoelectric element more than the second electrode region, and therefore, in a configuration in which the area of ​​the first electrode region is smaller than the area of ​​the second electrode region, it is difficult for the second electrode to reliably hinder the displacement of the piezoelectric element.

[0014] The above aspect may include a plurality of second electrodes. The piezoelectric element may have a pair of main surfaces facing each other in a direction in which the plurality of second electrodes face each other, and side surfaces connecting the pair of main surfaces. At least one second electrode of the plurality of second electrodes may be an internal electrode disposed within the piezoelectric element. The internal electrode may have a first internal electrode region facing another second electrode of the plurality of second electrodes, and a second internal electrode region that is narrower than the first internal electrode region and has one end exposed to the side surface and physically connected to the first electrode, and the other end continuous with the first internal electrode region. The first electrode region may include at least the second internal electrode region. In a configuration in which the first electrode region includes at least the second internal electrode region, the at least one second electrode, which is an internal electrode, is less likely to generate heat and less likely to inhibit the displacement of the piezoelectric element. Therefore, even in a configuration in which the piezoelectric element includes an internal electrode, this configuration suppresses deterioration of the displacement characteristics.

[0015] In the above aspect, the first electrode region may include a part of the first internal electrode region that is continuous with the second internal electrode region. A configuration in which the first electrode region includes the part of the first internal electrode region suppresses heat generation in the second electrode compared to a configuration in which the first electrode region does not include the part of the first internal electrode region.

[0016] In the above-described embodiment, the portion of the first internal electrode region may be wider than the second internal electrode region, and the second internal electrode region may be located within a width range of the portion of the first internal electrode region when viewed from a direction perpendicular to a side surface to which one end of the second internal electrode region is exposed. A configuration in which the portion of the first internal electrode region is wider than the second internal electrode region and the second internal electrode region is located within the width range of the portion of the first internal electrode region reliably suppresses heat generation in the second electrode.

[0017] In the above-described one aspect, when viewed from the direction in which the plurality of second electrodes face each other, the boundary between the part of the first internal electrode region and the remainder of the first internal electrode region may be arc-shaped. In a configuration in which the boundary between the part of the first internal electrode region and the remainder of the first internal electrode region is arc-shaped, the first internal electrode region is less likely to hinder the displacement of the piezoelectric element body than in a configuration in which the boundary is not arc-shaped, for example, made up of a plurality of straight lines that intersect with each other. Therefore, the configuration in which the boundary is arc-shaped is even less likely to hinder the displacement of the piezoelectric element body.

[0018] In the above aspect, the area of ​​the second internal electrode region may be smaller than the area of ​​the first internal electrode region. The second internal electrode regions included in the first electrode region tend to hinder the displacement of the piezoelectric element more than the first internal electrode regions, and therefore, in a configuration in which the area of ​​the second internal electrode regions is smaller than the area of ​​the first internal electrode regions, the second electrode does not reliably hinder the displacement of the piezoelectric element.

[0019] In the above aspect, the plurality of second electrodes may be internal electrodes having a first internal electrode region and a second internal electrode region. In a configuration in which the plurality of second electrodes have first internal electrode regions and second internal electrode regions, the plurality of second electrodes are less likely to generate heat and less likely to inhibit the displacement of the piezoelectric element body, thereby further suppressing the deterioration of the displacement characteristics.

[0020] In the above aspect, the first electrode regions of the plurality of second electrodes may overlap each other when viewed from a direction in which the plurality of second electrodes face each other. A configuration in which the first electrode regions of the plurality of second electrodes overlap one another when viewed from the direction in which the plurality of second electrodes face one another further suppresses deterioration of the displacement characteristics.

[0021] In the above aspect, the first electrode may include a through-hole conductor disposed in the piezoelectric element, and the through-hole conductor may be physically connected to the first electrode region. Even if the first electrode includes a through-hole conductor, a configuration in which the through-hole conductor is physically connected to the first electrode region makes it difficult for the second electrode to generate heat and makes it difficult for the displacement of the piezoelectric element to be hindered.

[0022] The above-described aspect may include a plurality of second electrodes. When viewed from a direction in which the plurality of second electrodes face each other, the through-hole conductor may be located entirely inside a region of the first electrode to which the through-hole conductor is physically connected. In a configuration in which the through-hole conductor is entirely located inside the first electrode region to which the through-hole conductor is physically connected, the through-hole conductor is reliably connected to the first electrode region, and therefore this configuration reliably prevents the second electrode from generating heat and reliably prevents the displacement of the piezoelectric element body from being hindered. [Effects of the Invention]

[0023] One aspect of the present invention provides a piezoelectric element that suppresses deterioration of displacement characteristics. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a perspective view showing a piezoelectric element according to a first embodiment. [Figure 2] 1 is a diagram showing a cross-sectional configuration of a piezoelectric element according to a first embodiment. [Figure 3] FIG. 1 is an exploded perspective view of a piezoelectric element according to a first embodiment. [Figure 4] FIG. 2 is a diagram showing the configuration of an internal electrode. [Figure 5] FIG. 2 is a diagram showing a cross section of the first electrode region. [Figure 6] FIG. 4 is a diagram showing a cross section of the second electrode region. [Figure 7] FIG. 2 is a diagram showing the configuration of an internal electrode. [Figure 8] FIG. 2 is a diagram showing the configuration of an internal electrode. [Figure 9] FIG. 2 is a diagram showing the configuration of an internal electrode. [Figure 10] FIG. 10 is a perspective view showing a piezoelectric element according to a second embodiment. [Figure 11] FIG. 4 is a diagram showing a cross-sectional configuration of a piezoelectric element according to a second embodiment. [Figure 12] FIG. 10 is an exploded perspective view of a piezoelectric element according to a second embodiment. [Figure 13] FIG. 2 is a diagram showing the configuration of an internal electrode. [Figure 14] FIG. 2 is a diagram showing the configuration of an internal electrode. [Figure 15] FIG. 2 is a diagram showing the configuration of an internal electrode. [Figure 16] FIG. 10 is a diagram showing a cross-sectional configuration of a piezoelectric element according to a modified example. [Figure 17] FIG. 10 is a diagram showing a cross-sectional configuration of a piezoelectric element according to another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0026] (First embodiment) The configuration of the piezoelectric element PD1 according to the first embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a perspective view showing the piezoelectric element according to the first embodiment. Fig. 2 is a diagram showing the cross-sectional configuration of the piezoelectric element according to the first embodiment. Fig. 3 is an exploded perspective view of the piezoelectric element according to the first embodiment. Hatching has been omitted in Fig. 2 to clearly show each part.

[0027] As shown in FIGS. 1 to 3, the piezoelectric element PD1 includes a piezoelectric body 1 and multiple electrodes 10. In this embodiment, the electrode 10 includes multiple electrodes 10a and 10b. The electrode 10a includes an electrode 11 and multiple electrodes 21 and 22. The electrode 10b includes an electrode 13 and multiple electrodes 21 and 22. The electrode 10 includes multiple electrodes 11 and 13 and multiple electrodes 21 and 22. The electrodes 11 and 13 are arranged on the piezoelectric body 1. The electrodes 21 and 22 are arranged on the piezoelectric body 1 so as to face each other. For example, when the electrodes 11 and 13 constitute first electrodes, the electrodes 21 and 22 constitute second electrodes.

[0028] In this embodiment, the piezoelectric element 1 has a rectangular parallelepiped shape. The piezoelectric element 1 has a pair of opposing main surfaces 1a and 1b and a side surface 1c connecting the main surfaces 1a and 1b. The side surface 1c has a pair of opposing side surfaces 1c1 and 1c2 and a pair of opposing side surfaces 1c3 and 1c4. The main surfaces 1a and 1b and the side surfaces 1c1, 1c2, 1c3, and 1c4 form the outer surface of the piezoelectric element 1. The main surfaces 1a and 1b and the side surfaces 1c1, 1c2, and the side surfaces 1c3 and 1c4 have a rectangular shape. In this specification, the term "rectangular parallelepiped shape" includes a rectangular parallelepiped shape with chamfered corners and ridges, and a rectangular parallelepiped shape with rounded corners and ridges. In this specification, the term "rectangular shape" includes, for example, a shape with chamfered corners and a shape with rounded corners.

[0029] The principal surfaces 1a and 1b face each other in the first direction D1. The principal surfaces 1a and 1b define both ends of the piezoelectric body 1 in the first direction D1. The principal surfaces 1a and 1b are, for example, perpendicular to the first direction D1. The side surfaces 1c1 and 1c2 are adjacent to the principal surfaces 1a and 1b and face each other in a second direction D2 that intersects the first direction D1. The side surfaces 1c1 and 1c2 define both ends of the piezoelectric body 1 in the second direction D2. The side surfaces 1c1 and 1c2 are, for example, perpendicular to the second direction D2. The side surfaces 1c3 and 1c4 are adjacent to the principal surfaces 1a and 1b and the side surfaces 1c1 and 1c2 and face each other in a third direction D3 that intersects the first direction D1 and the second direction D2. The side surfaces 1c3 and 1c4 define both ends of the piezoelectric body 1 in the third direction D3. The side surfaces 1c3 and 1c4 are, for example, perpendicular to the third direction D3. In this embodiment, the first direction D1, the second direction D2, and the third direction D3 are perpendicular to one another.

[0030] The principal surfaces 1a and 1b extend in the second direction D2 to connect the side surface 1c1 and the side surface 1c2. The principal surfaces 1a and 1b extend in the third direction D3 to connect the side surface 1c3 and the side surface 1c4. The side surfaces 1c1 and 1c2 extend in the first direction D1 to connect the principal surfaces 1a and 1b. The side surfaces 1c1 and 1c2 extend in the third direction D3 to connect the side surfaces 1c3 and 1c4. The side surfaces 1c3 and 1c4 extend in the first direction D1 to connect the principal surfaces 1a and 1b. The side surfaces 1c3 and 1c4 extend in the second direction D2 to connect the side surfaces 1c1 and 1c2. The principal surfaces 1a and 1b, the side surfaces 1c1 and 1c2, and the side surfaces 1c3 and 1c4 may be indirectly adjacent to each other. In this case, ridges are located between the main surfaces 1a and 1b, the side surfaces 1c1 and 1c2, and the side surfaces 1c3 and 1c4.

[0031] The length of the piezoelectric element 1 in the first direction D1, i.e., the thickness of the piezoelectric element 1, is, for example, 0.2 mm. The length of the piezoelectric element 1 in the second direction D2 is, for example, 10 mm. The length of the piezoelectric element 1 in the third direction D3 is, for example, 20 mm. In the piezoelectric element 1, the second direction D2 is, for example, the long side direction.

[0032] The piezoelectric element 1 includes, for example, multiple piezoelectric layers 3a, 3b, 3c, 3d, and 3e. In this embodiment, the piezoelectric element 1 includes five piezoelectric layers 3a, 3b, 3c, 3d, and 3e. The piezoelectric layers 3a, 3b, 3c, 3d, and 3e are stacked, for example, in a first direction D1. The piezoelectric layer 3a has a main surface 1a. The piezoelectric layer 3e has a main surface 1b. The piezoelectric layers 3b, 3c, and 3d are located between the piezoelectric layer 3a and the piezoelectric layer 3e. In this embodiment, the piezoelectric layers 3a, 3b, 3c, 3d, and 3e have the same thickness. In this specification, "same" does not necessarily mean that the values ​​are the same. The thicknesses may be considered to be equal even if there are slight differences, manufacturing errors, or measurement errors within a predetermined range. In this embodiment, the piezoelectric element PD1 is a so-called stacked piezoelectric element.

[0033] The piezoelectric layers 3a, 3b, 3c, 3d, and 3e are made of a piezoelectric material. In this embodiment, the piezoelectric layers 3a, 3b, 3c, 3d, and 3e are made of a piezoelectric ceramic material. Examples of the piezoelectric ceramic material include PZT [Pb(Zr,Ti)O], PT (PbTiO), PLZT [(Pb,La)(Zr,Ti)O], barium titanate (BaTiO), BNT (bismuth sodium titanate), and KNN (potassium sodium niobate). The piezoelectric layers 3a, 3b, 3c, 3d, and 3e are made of, for example, a sintered ceramic green sheet containing the above-described piezoelectric ceramic material. In an actual piezoelectric element 1, the piezoelectric layers 3a, 3b, 3c, 3d, and 3e are integrated to the extent that the boundaries between the piezoelectric layers 3a, 3b, 3c, 3d, and 3e are indistinguishable.

[0034] In this embodiment, the electrodes 11 and 13 are arranged continuously on the principal surface 1a and the side surface 1c3. The electrodes 11 and 13 have, for example, a principal surface electrode portion provided on the principal surface 1a and a side surface electrode portion provided on the side surface 1c3. The principal surface electrode portion and the side surface electrode portion of the electrodes 11 and 13 are, for example, integrally formed with each other. The electrodes 11 and 13 are aligned in the second direction D2. For example, voltages of opposite polarities are applied to the electrodes 11 and 13.

[0035] Electrode 11 is disposed on the principal surface 1a and the side surface 1c3 closer to the side surface 1c1 than the center of the principal surface 1a in the second direction D2. Electrode 13 is disposed on the principal surface 1a and the side surface 1c3 closer to the side surface 1c2 than the center of the principal surface 1a in the second direction D2. Electrodes 11 and 13 are spaced apart from each other in the second direction D2 on the principal surface 1a. Electrodes 11 and 13 are aligned in the second direction D2 on the principal surface 1a. The side surface electrode portion of electrode 11 extends from the edge of the side surface 1c3 on the principal surface 1b side to the edge on the principal surface 1a side and is connected to the principal surface electrode portion of electrode 11. The side surface electrode portion of electrode 13 extends from the edge of the side surface 1c3 on the principal surface 1b side to the edge on the principal surface 1a side and is connected to the principal surface electrode portion of electrode 13. The principal surface electrode portions of electrodes 11 and 13 are disposed on the edge of the principal surface 1a on the side surface 1c3 side.

[0036] The principal surface electrode portions of the electrodes 11 and 13 have, for example, a rectangular shape when viewed from the first direction D1. The principal surface electrode portions of the electrodes 11 and 13 have, for example, the same shape when viewed from the first direction D1. When viewed from the first direction D1, the long side direction of the principal surface electrode portions of the electrodes 11 and 13 coincides with, for example, the third direction D3, and the short side direction of the principal surface electrode portions of the electrodes 11 and 13 coincides with, for example, the second direction D2.

[0037] The side electrode portions of the electrodes 11 and 13 have, for example, a rectangular shape when viewed from the third direction D3. The side electrode portions of the electrodes 11 and 13 have, for example, the same shape when viewed from the third direction D3. When viewed from the third direction D3, for example, the long side direction of the side electrode portions of the electrodes 11 and 13 coincides with the first direction D1, and the short side direction of the side electrode portions of the electrodes 11 and 13 coincides with the second direction D2.

[0038] The electrodes 11 and 13 contain a conductive material such as Ag, Pd, Pt, Cu, or an Ag-Pd alloy. The electrodes 11 and 13 are formed, for example, by sintering a conductive paste containing the conductive material.

[0039] Electrodes 11 and 13 may be arranged continuously with principal surface 1a and any of side surfaces 1c1, 1c2, and 1c4. Electrodes 11 and 13 may be arranged continuously with principal surface 1b and any of side surfaces 1c1, 1c2, 1c3, and 1c4. For example, electrode 11 may be arranged continuously with principal surface 1a and any of side surfaces 1c1, 1c2, 1c3, and 1c4, and electrode 13 may be arranged continuously with principal surface 1b and any of side surfaces 1c1, 1c2, 1c3, and 1c4. For example, electrode 11 may be arranged continuously with principal surface 1b and any of side surfaces 1c1, 1c2, 1c3, and 1c4, and electrode 13 may be arranged continuously with principal surface 1a and any of side surfaces 1c1, 1c2, 1c3, and 1c4.

[0040] The multiple electrodes 21, 22 are electrically connected to corresponding electrodes 11, 13 among the multiple electrodes 11, 13. In this embodiment, the multiple electrodes 21 are electrically connected to the electrode 11. The multiple electrodes 22 are electrically connected to the electrode 13. The electrode 11 is electrically connected to the electrode 21 and another electrode 21. The electrode 13 is electrically connected to the electrode 22 and another electrode 22. The electrodes 21, 22 are arranged at different positions (layers) in the first direction D1. The electrodes 21, 22 face each other with a gap in between in the first direction D1. The electrode 21, the electrode 22, the other electrode 21, and the other electrode 22 are, for example, arranged in this order in the first direction D1.

[0041] The electrode 21 is located between the piezoelectric layer 3a and the piezoelectric layer 3b. The electrode 22 is located between the piezoelectric layer 3b and the piezoelectric layer 3c. The other electrode 21 is located between the piezoelectric layer 3c and the piezoelectric layer 3d. The other electrode 22 is located between the piezoelectric layer 3d and the piezoelectric layer 3e. The piezoelectric layer 3a is located between the main surface 1a and the electrode 21. The piezoelectric layer 3b is located between the electrode 21 and the electrode 22. The piezoelectric layer 3c is located between the electrode 22 and the other electrode 21. The piezoelectric layer 3d is located between the other electrode 21 and the other electrode 22. The piezoelectric layer 3e is located between the other electrode 22 and the main surface 1b.

[0042] At least one of the multiple electrodes 21, 22 has an electrode region E1 and an electrode region E2. In this embodiment, the multiple electrodes 21, 22 have an electrode region E1 and an electrode region E2. The electrode region E1 is physically connected to the corresponding electrodes 11, 13. The electrode region E1 of the electrode 21 is physically connected to the electrode 11. The electrode region E1 of the electrode 22 is physically connected to the electrode 13. For example, when the electrode region E1 constitutes a first electrode region, the electrode region E2 constitutes a second electrode region.

[0043] The electrode region E1 covers the element region B1 of the piezoelectric element 1. The electrode region E1 of the electrode 21 covers the element region B1 of the piezoelectric layer 3b. The electrode region E1 of the electrode 22 covers the element region B1 of the piezoelectric layers 3b and 3c. The electrode region E1 of the other electrode 21 covers the element region B1 of the piezoelectric layers 3c and 3d. The electrode region E1 of the other electrode 22 covers the element region B1 of the piezoelectric layer 3d. For example, if the element region B1 constitutes the first element region, the element region B2 constitutes the second element region.

[0044] The electrode region E2 covers an element region B2 that is different from the element region B1. The electrode region E2 of the electrode 21 covers the element region B2 of the piezoelectric layer 3b. The electrode region E2 of the electrode 22 covers the element region B2 of the piezoelectric layers 3b and 3c. The electrode region E2 of the other electrode 21 covers the element region B2 of the piezoelectric layers 3c and 3d. The electrode region E2 of the other electrode 22 covers the element region B2 of the piezoelectric layer 3d.

[0045] The area of ​​the electrode region E1 is, for example, smaller than the area of ​​the electrode region E2 in the electrodes 21 and 22. In the electrodes 21 and 22, the ratio of the area of ​​the electrode region E1 to the total area of ​​the electrode region E1 and the electrode region E2 is, for example, 3 to 10%.

[0046] Fig. 4 shows the electrodes 21 and 22 as viewed from the first direction D1. To clearly show each part, Fig. 4 shows the electrode area E1 of the electrode 21 with a solid line and the electrode area E1 of the electrode 22 with a dashed line.

[0047] As shown in FIG. 4, the electrodes 21 and 22 have an internal electrode region P1 and an internal electrode region P2. The internal electrode region P1 includes the electrode region E1 and the electrode region E2. The internal electrode region P2 is continuous with the internal electrode region P1. The internal electrode region P2 includes the electrode region E1. The internal electrode region P1 is continuous with the internal electrode region P2, for example, in a third direction D3. The internal electrode region P1 faces another electrode 21 or 22 among the multiple electrodes 21 and 22. In the example shown in FIG. 4, the internal electrode region P1 of the electrode 21 faces the electrode 22. The internal electrode region P1 of the electrode 22 faces the electrode 21. The internal electrode region P1 faces the electrodes 21 and 22, for example, in the first direction D1. For example, if the internal electrode region P1 constitutes a first internal electrode region, the internal electrode region P2 constitutes a second internal electrode region.

[0048] The internal electrode region P1 is located within the piezoelectric element 1. The internal electrode region P1 is not exposed on the principal surfaces 1a, 1b or the side surfaces 1c1, 1c2, 1c3, or 1c4. The internal electrode region P2 is not exposed on the principal surfaces 1a, 1b or the side surfaces 1c1, 1c2. The internal electrode region P2 has one end ED1 and the other end ED2. The one end ED1 is exposed on the side surface 1c3 and is physically connected to the corresponding electrodes 11, 13. The other end ED2 is continuous with the internal electrode region P1. The one end ED1 and the other end ED2 face each other, for example, in the third direction D3. The internal electrode region P2 is located between the internal electrode region P1 and the side electrode portions of the electrodes 11, 13 in the second direction D2. The one end ED1 is connected to the side electrode portions of the corresponding electrodes 11, 13, for example, on the side surface 1c3. One end ED1 of electrode 21 is connected to the side electrode portion of electrode 11, for example, at side surface 1c3. One end ED1 of electrode 22 is connected to the side electrode portion of electrode 13, for example, at side surface 1c3. In electrode 21, as viewed from first direction D1, internal electrode region P2 is, for example, closer to side surface 1c1 than to side surface 1c2. In electrode 22, as viewed from first direction D1, internal electrode region P2 is, for example, closer to side surface 1c2 than to side surface 1c1.

[0049] The electrode region E1 includes at least the internal electrode region P2. Therefore, the electrode region E1 includes a portion E3 of the internal electrode region P1 that is continuous with the internal electrode region P2, and also includes a portion E4 of the internal electrode region P2 that is part of the electrode region E1. In this embodiment, for example, the portion E3 of the electrode region E1 and the remaining portion E5 of the internal electrode region P1 are located in the internal electrode region P1. For example, the portion E4 of the electrode region E1 is located in the internal electrode region P2.

[0050] When viewed from the first direction D1, the internal electrode region P1 has, for example, a rectangular shape. For example, the internal electrode region P1 has a rectangular shape. When viewed from the first direction D1, the long side direction of the internal electrode region P1 coincides with, for example, the third direction D3, and the short side direction of the internal electrode region P1 coincides with, for example, the second direction D2. When viewed from the first direction D1, the internal electrode region P2 has, for example, a rectangular shape. When viewed from the first direction D1, the long side direction of the internal electrode region P2 coincides with, for example, the second direction D2, and the short side direction of the internal electrode region P2 coincides with, for example, the third direction D3.

[0051] The portion E3 of the internal electrode region P1 is, for example, wider than the internal electrode region P2. Therefore, the width W3 of the portion E3 in the second direction D2 is, for example, wider than the width W2 of the internal electrode region P2 in the second direction D2. When viewed in the third direction D3, the internal electrode region P2 is located within the range of the width W3 of the portion E3 of the internal electrode region P1.

[0052] When viewed from the first direction D1, the boundary ED3 between the part E3 of the internal electrode region P1 and the remaining part E5 of the internal electrode region P1 has, for example, an arc shape. Therefore, the part E3 has, for example, a fan shape. The boundary ED3 may have, for example, a semicircular arc shape.

[0053] In the electrodes 21 and 22, the area of ​​the internal electrode region P2 is, for example, smaller than the area of ​​the internal electrode region P1. In the electrodes 21 and 22, the ratio of the area of ​​the internal electrode region P2 to the total area of ​​the internal electrode region P1 and the area of ​​the internal electrode region P2 is, for example, 0.3 to 2%.

[0054] The electrode regions E1 of the electrodes 21 and 22 overlap each other when viewed from the first direction D1. Therefore, the electrode region E1 of the electrode 21 and the electrode region E1 of the electrode 22 overlap each other when viewed from the first direction D1. In this embodiment, the ratio of the area of ​​the electrodes 21 and 22 occupied by the electrode regions E1 overlapping each other is, for example, 10 to 40%.

[0055] Fig. 5 shows a portion of a cross-section obtained by cutting the electrode region E1 of the electrode 21 in the thickness direction along the cutting line CL1. Fig. 6 shows a portion of a cross-section obtained by cutting the electrode region E2 of the electrode 21 in the thickness direction along the cutting line CL1. Figs. 5 and 6 show the cross-section as viewed from the second direction D2. The thickness direction of the electrode regions E1 and E2 coincides with the first direction D1, for example.

[0056] As shown in FIG. 5, the electrode region E1 of the electrode 21 covers the element region B1 of the piezoelectric layer 3b. Electrode area E1 of electrode 21 A gap 25 is formed in the electrode region E1 of the electrode 21. The gap 25 is formed in a region where the electrode region E1 of the electrode 21 does not cover the element body region B1 of the piezoelectric layer 3b. In the present embodiment, in the region where the electrode region E1 covers the element body region B1, for example, the electrode region E1 is in contact with the element body region B1. Therefore, the region where the electrode region E1 is not in contact with the element body region B1 is not included in the region where the electrode region E1 covers the element body region B1. The percentage of the electrode region E1 covering the element body region B1 may be referred to as the coverage percentage of the electrode region E1 hereinafter. The coverage percentage of the electrode region E1 is, for example, 80 to 90%. In a configuration where the electrode region E1 is in contact with the element body region B1, the coverage percentage of the electrode region E1 may be the percentage of the area of ​​the region where the electrode region E1 is in contact with the element body region B1 to the area of ​​the region defined by the outer edge of the electrode region E1.

[0057] As shown in FIG. 6, the electrode 21 covers the element region B2 of the piezoelectric layer 3b. Electrode region E2 of electrode 21A gap 27 is formed in the electrode 21. The gap 27 indicates a region where the electrode region E2 of the electrode 21 does not cover the element body region B2 of the piezoelectric layer 3b. In the present embodiment, in the region where the electrode region E2 covers the element body region B2, for example, the electrode region E2 is in contact with the element body region B2. Therefore, the region where the electrode region E2 is not in contact with the element body region B2 is not included in the region where the electrode region E2 covers the element body region B2. The percentage of the electrode region E2 covering the element body region B2 may be referred to as the coverage percentage of the electrode region E2 hereinafter. The coverage percentage of the electrode region E2 is, for example, 70 to 80%. In a configuration where the electrode region E2 is in contact with the element body region B2, the coverage percentage of the electrode region E2 may be the ratio of the area of ​​the region where the electrode region E2 is in contact with the element body region B2 to the area of ​​the region defined by the outer edge of the electrode region E2. In the present embodiment, the coverage percentage of the electrode region E1 is greater than the coverage percentage of the electrode region E2. In this specification, "covered" means that the element body regions B1 and B2 are not covered by the electrode regions E1 and E2, and the surfaces of the element body regions B1 and B2 are exposed.

[0058] The coverage ratio is, for example, a cross-sectional coverage ratio. The cross-sectional coverage ratio of the electrode regions E1, E2 is, for example, the ratio of the electrode regions E1, E2 covering the element body regions B1, B2, respectively, in a cross section obtained by cutting at least one electrode 21, 22 in the thickness direction. The cross-sectional coverage ratio of the electrode regions E1, E2 can be calculated, for example, as follows: A cross-sectional photograph of the piezoelectric element PD1 is obtained at a position including the electrode regions E1, E2. The cross-sectional photograph is a photograph of a cross section of the piezoelectric element PD1 taken along a plane perpendicular to the side surfaces 1c3, 1c4. The obtained cross-sectional photograph is subjected to image processing using software. This image processing distinguishes the boundaries between the electrode regions E1, E2, the element body regions B1, B2, and the voids 25, 27, and calculates the cross-sectional coverage ratio of the electrode regions E1, E2.

[0059] The coverage ratio is, for example, the surface coverage ratio. The surface coverage ratio of the electrode regions E1 and E2 is, for example, the ratio of the electrode regions E1 and E2 covering the element regions B1 and B2, respectively, when the surfaces of the electrode regions E1 and E2 are viewed from a direction perpendicular to the electrode regions E1 and E2. The surface coverage ratio of the electrode regions E1 and E2 can be calculated, for example, as follows: A photograph of the surfaces of the electrode regions E1 and E2 is taken from a direction perpendicular to the electrode regions E1 and E2. The acquired surface photograph is subjected to image processing using software. This image processing determines the boundaries between the electrode regions E1 and E2 and the voids 25 and 27, and calculates the areas of the regions defined by the outer edges of the electrode regions E1 and E2 and the total area of ​​the voids 25 and 27 on the photograph. The total area of ​​the void 25 is divided by the area of ​​the region defined by the outer edge of the electrode region E1 to obtain a quotient. This quotient is the surface coverage ratio of the electrode region E1. The total area of ​​the voids 27 is divided by the area of ​​the region defined by the outer edge of the electrode region E2 to obtain a quotient. This quotient is the surface coverage ratio in the electrode region E2. The surface coverage ratio can be determined, for example, when the electrode regions E1 and E2 can be peeled off at the boundaries between the electrode regions E1 and E2 and the element body regions B1 and B2. If peeling is possible, for example, the surface of the electrode regions E1 and E2 in a state where they have been peeled off from the element body regions B1 and B2 is photographed to determine the surface coverage ratio. The surface coverage ratio in the electrode region E1 may be the ratio of the total area of ​​the voids 25 within each region of a predetermined size on the surface of the electrode region E1. The surface coverage ratio in the electrode region E2 may be the ratio of the total area of ​​the voids 27 within each region of a predetermined size on the surface of the electrode region E2. The predetermined size may be, for example, 60 μm × 45 μm.

[0060] In the piezoelectric element 1, the region of the piezoelectric layer 3b sandwiched between the internal electrode region P1 of the electrode 21 and the internal electrode region P1 of the electrode 22, the region of the piezoelectric layer 3c sandwiched between the internal electrode region P1 of the electrode 22 and the internal electrode region P1 of the other electrode 21, and the region of the piezoelectric layer 3d sandwiched between the internal electrode region P1 of the other electrode 21 and the internal electrode region P1 of the other electrode 22 constitute piezoelectrically active regions. Active regions are formed between the internal electrode region P1 of the electrode 21 and the internal electrode region P1 of the electrode 22, between the internal electrode region P1 of the electrode 22 and the internal electrode region P1 of the other electrode 21, and between the internal electrode region P1 of the other electrode 21 and the internal electrode region P1 of the other electrode 22. When viewed from the first direction D1, in the piezoelectric layers 3b, 3c, and 3d, the outer edges of the regions where the internal electrode region P1 of the electrode 21 and the internal electrode region P1 of the electrode 22, the internal electrode region P1 of the electrode 22 and the internal electrode region P1 of the other electrode 21, and the internal electrode region P1 of the other electrode 21 and the internal electrode region P1 of the other electrode 22 overlap define the boundaries between the active regions and the inactive regions that are piezoelectrically inactive. In the piezoelectric element 1, the piezoelectric layer 3a and the piezoelectric layer 3e form the inactive regions.

[0061] The electrodes 21 and 22 are made of a conductive material. Examples of the conductive material include Ag, Pd, Pt, Cu, and an Ag-Pd alloy. The electrodes 21 and 22 are, for example, sintered bodies of a conductive paste containing the conductive material. The electrodes 21 and 22 are formed by firing electrode patterns corresponding to the electrodes 21 and 22. Each electrode pattern is made of a conductive paste. The conductive paste is applied to the ceramic green sheet by, for example, a screen printing method. The electrode patterns are fired together with the ceramic green sheet. The screen printing method uses a screen printing plate. The screen printing plate includes, for example, a mesh. The mesh has a mask formed thereon with openings corresponding to the electrode patterns. The conductive paste placed on the mesh and mask passes through the openings and is applied to the ceramic green sheet. An emulsion is used to form the mask. The electrode regions E1 and E2 have different coverage rates, which can be achieved, for example, by controlling the printing conditions when forming the electrode patterns corresponding to the electrodes 21 and 22. The printing conditions include, for example, emulsion thickness, printing speed, or mesh opening ratio.

[0062] Fig. 7 shows another example configuration of electrodes 21 and 22 as viewed from first direction D1. To clearly show each part, Fig. 7 shows electrode region E1 of electrode 21 with a solid line and electrode region E1 of electrode 22 with a dashed line.

[0063] In the example shown in FIG. 7, the electrode region E1 includes a portion E3 and a portion E4. For example, the portion E3 and the remainder E5 are located in the internal electrode region P1. For example, the portion E4 is located in the internal electrode region P2. The portion E3 of the internal electrode region P1 is, for example, wider than the internal electrode region P2. Therefore, for example, the width W3 of the portion E3 in the second direction D2 is wider than the width W2 of the internal electrode region P2 in the second direction D2. When viewed from the third direction D3, the internal electrode region P2 is located within the range of the width W3 of the portion E3 of the internal electrode region P1.

[0064] When viewed from the first direction D1, the boundary ED3 between the portion E3 of the internal electrode region P1 and the remainder E5 of the internal electrode region P1 has, for example, a linear shape. Therefore, when viewed from the first direction D1, the portion E3 has, for example, a rectangular shape. When viewed from the first direction D1, the long side direction of the portion E3 coincides, for example, with the second direction D2, and the short side direction of the portion E3 coincides with the third direction D3. When viewed from the first direction D1, the portion E4 has, for example, a rectangular shape. When viewed from the first direction D1, the long side direction of the portion E4 coincides, for example, with the second direction D2, and the short side direction of the portion E4 coincides with the third direction D3.

[0065] 7, the area of ​​the electrode region E1 is smaller than the area of ​​the electrode region E2 in the electrodes 21 and 22. In the electrodes 21 and 22, the ratio of the area of ​​the electrode region E1 to the total area of ​​the electrode region E1 and the electrode region E2 is, for example, 3 to 10%.

[0066] The electrode regions E1 of the electrodes 21 and 22 overlap each other when viewed from the first direction D1. Therefore, the electrode region E1 of the electrode 21 and the electrode region E1 of the electrode 22 overlap each other when viewed from the first direction D1. In this modification, the ratio of the area of ​​the electrodes 21 and 22 occupied by the electrode regions E1 overlapping each other is, for example, 10 to 40%.

[0067] Fig. 8 shows yet another example configuration of electrodes 21 and 22 as viewed from first direction D1. To clearly show each part, Fig. 8 shows electrode region E1 of electrode 21 with a solid line and electrode region E1 of electrode 22 with a dashed line.

[0068] 8, for example, a portion E3 and a remainder E5 are located in the internal electrode region P1. For example, a portion E4 is located in the internal electrode region P2. The portion E3 of the internal electrode region P1 has, for example, the same width as the internal electrode region P2. Therefore, the width W3 in the second direction of the portion E3 is, for example, the same as the width W2 of the internal electrode region P2.

[0069] When viewed from the first direction D1, the boundary ED3 between the portion E3 of the internal electrode region P1 and the remaining portion E5 of the internal electrode region P1 has, for example, a linear shape. Therefore, when viewed from the first direction D1, the portion E3 has, for example, a rectangular shape. When viewed from the first direction D1, the long side direction of the portion E3 coincides, for example, with the third direction D3, and the short side direction of the portion E3 coincides with the second direction D2. When viewed from the first direction D1, the portion E4 has, for example, a rectangular shape. When viewed from the first direction D1, the long side direction of the portion E4 coincides, for example, with the second direction D2, and the short side direction of the portion E4 coincides with the third direction D3. In this modification, the electrode regions E1 of the electrodes 21 and 22 do not overlap with each other when viewed from the first direction D1.

[0070] The area of ​​the electrode region E1 is, for example, smaller than the area of ​​the electrode region E2 in the electrodes 21 and 22. In the electrodes 21 and 22, the ratio of the area of ​​the electrode region E1 to the total area of ​​the electrode region E1 and the electrode region E2 is, for example, 2 to 12%.

[0071] Fig. 9 shows yet another example configuration of electrodes 21 and 22 as viewed from first direction D1. To clearly show each part, Fig. 9 shows electrode region E1 of electrode 21 with a solid line and electrode region E1 of electrode 22 with a dashed line.

[0072] 9, the electrode region E1 includes a portion E4. In this modification, the portion E4 is located in the internal electrode region P2. In this modification, the portion E3 is not located in the internal electrode region P1. The width W4 of the portion E4 in the second direction D2 is, for example, the same as the width W2 of the internal electrode region P2.

[0073] When viewed from the first direction D1, the portion E4 has, for example, a rectangular shape. When viewed from the first direction D1, the long side direction of the portion E4 coincides with, for example, the second direction D2, and the short side direction of the portion E4 coincides with, for example, the third direction D3. In this modification, the electrode regions E1 of the electrodes 21 and 22 do not overlap with each other when viewed from the first direction D1.

[0074] The area of ​​the electrode region E1 is, for example, smaller than the area of ​​the electrode region E2 in the electrodes 21 and 22. In the electrodes 21 and 22, the ratio of the area of ​​the electrode region E1 to the total area of ​​the electrode region E1 and the electrode region E2 is, for example, 0.3 to 2%.

[0075] As described above, the piezoelectric element PD1 according to this embodiment and the modified examples includes the piezoelectric body 1, electrodes 11 and 13 arranged on the piezoelectric body 1, and electrodes 21 and 22 arranged on the piezoelectric body 1 and electrically connected to electrodes 11 and 13. Electrodes 21 and 22 are physically connected to electrodes 11 and 13, and have an electrode region E1 covering element body region B1 of the piezoelectric body 1, and an electrode region E2 covering element body region B2, which is different from element body region B1, of the piezoelectric body 1. The proportion of element body region B1 covered by electrode region E1 is greater than the proportion of element body region B2 covered by electrode region E2.

[0076] In piezoelectric element PD1, the proportion of electrode region E1 covering element body region B1 is greater than the proportion of electrode region E2 covering element body region B2. Therefore, electrodes 21 and 22 are less likely to generate heat and less likely to inhibit the displacement of piezoelectric element 1. As a result, piezoelectric element PD1 suppresses deterioration of its displacement characteristics.

[0077] In the piezoelectric element PD1, the electrodes 21 and 22 have an electrode region E1 and an electrode region E2. In this case, the electrodes 21 and 22 are unlikely to generate heat and are unlikely to hinder the displacement of the piezoelectric element 1. Therefore, the piezoelectric element PD1 is further prevented from deteriorating in displacement characteristics.

[0078] In the piezoelectric element PD1, the area of ​​the electrode region E1 is smaller than the area of ​​the electrode region E2. In this case, electrode region E1 tends to inhibit the displacement of the piezoelectric element 1 more than electrode region E2. Therefore, in a configuration in which the area of ​​electrode region E1 is smaller than the area of ​​electrode region E2, it is difficult for electrodes 21 and 22 to reliably inhibit the displacement of the piezoelectric element 1.

[0079] The piezoelectric element PD1 includes multiple second electrodes. The piezoelectric body 1 has a pair of principal surfaces 1a, 1b facing each other in the first direction D1 and side surfaces 1c3, 1c4 connecting the pair of principal surfaces 1a, 1b. At least one of the multiple electrodes 21, 22 is disposed within the piezoelectric body 1. Each electrode 21, 22 has an internal electrode region P1 facing another of the multiple electrodes 21, 22, one end ED1 exposed to the side surface 1c3 and physically connected to the electrodes 11, 13, and the other end ED2 continuous with the internal electrode region P1, and an internal electrode region P2 narrower than the internal electrode region P1. The electrode region E1 includes at least the internal electrode region P2. In this case, at least one of the electrodes 21 and 22, which are internal electrodes, is unlikely to generate heat and is unlikely to inhibit the displacement of the piezoelectric element 1. Therefore, even if the piezoelectric element 1 has a configuration including an internal electrode, the piezoelectric element PD1 suppresses deterioration of its displacement characteristics.

[0080] In the piezoelectric element PD1, the electrode region E1 may further include a portion E3 of the internal electrode region P1 that is continuous with the internal electrode region P2. In this case, the piezoelectric element PD1 suppresses heat generation from the electrodes 21 and 22 compared to a configuration in which the electrode region E1 does not include the part E3 of the internal electrode region P1.

[0081] In the piezoelectric element PD1, the portion E3 of the internal electrode region P1 is wider than the internal electrode region P2. When viewed from the third direction D3, the internal electrode region P2 is located within the width range of the portion E3 of the internal electrode region P1. In this case, the piezoelectric element PD1 reliably suppresses the heating of the electrodes 21 and 22.

[0082] In the piezoelectric element PD1, the boundary between the part E3 of the internal electrode region P1 and the remaining part E5 of the internal electrode region P1 has an arc shape when viewed from the first direction D1. In this case, compared to a configuration in which the boundary is not arc-shaped, for example, consisting of multiple intersecting straight lines, the internal electrode region P1 is less likely to obstruct the displacement of the piezoelectric element 1. Therefore, a configuration in which the boundary is arc-shaped is even less likely to obstruct the displacement of the piezoelectric element 1.

[0083] In the piezoelectric element PD1, the area of ​​the internal electrode region P2 is smaller than the area of ​​the internal electrode region P1. Compared to the internal electrode region P1, the internal electrode region P2 included in the electrode region E1 tends to inhibit the displacement of the piezoelectric element body 1. Therefore, in a configuration in which the area of ​​the internal electrode region P2 is smaller than the area of ​​the internal electrode region P1, it is difficult for the electrodes 21 and 22 to reliably inhibit the displacement of the piezoelectric element body 1.

[0084] In the piezoelectric element PD1, the plurality of electrodes 21 and 22 are electrodes 21 and 22 having an internal electrode region P1 and an internal electrode region P2. In this case, the plurality of electrodes 21, 22 are unlikely to generate heat and are unlikely to hinder the displacement of the piezoelectric element 1. Therefore, the piezoelectric element PD1 is further prevented from deteriorating in displacement characteristics.

[0085] In the piezoelectric element PD1, the electrode regions E1 of the multiple electrodes 21 and 22 overlap each other when viewed from the first direction D1. In this case, the piezoelectric element PD1 further suppresses the deterioration of the displacement characteristics.

[0086] (Second embodiment) The configuration of a piezoelectric element PD2 according to the second embodiment will be described with reference to FIGS. 10 to 15. FIG. 10 is a perspective view showing a piezoelectric element according to the second embodiment. FIG. 11 is a view showing a cross-sectional configuration of the piezoelectric element PD2 according to the second embodiment. FIG. 12 is an exploded perspective view of the piezoelectric element PD2 according to the second embodiment. FIGS. 13, 14, and 15 are views showing the configuration of the electrodes. Hatching is omitted in FIG. 11 to clearly show each part. In the piezoelectric element PD2, the configurations of electrodes 31, 32, and 33 and electrodes 41, 42, and 43 differ from those of the piezoelectric element PD1. The following mainly describes the differences from the piezoelectric element PD1.

[0087] As shown in FIGS. 10 to 12, the piezoelectric element PD2 includes a piezoelectric body 1 and multiple electrodes 30. In this embodiment, the electrodes 30 include multiple electrodes 30a, 30b, and 30c. The electrode 30a includes an electrode 31 and an electrode 43. The electrode 30b includes an electrode 32 and an electrode 42. The electrode 30c includes an electrode 33 and multiple electrodes 41. The electrode 30 includes multiple electrodes 31, 32, and 33, and multiple electrodes 41, 42, and 43. The electrodes 31, 32, and 33 are arranged on the piezoelectric body 1. The electrodes 41, 42, and 43 are arranged on the piezoelectric body 1 so as to face each other. The electrodes 41, 42, and 43 face each other in the first direction D1, for example. For example, when the electrodes 31, 32, and 33 constitute first electrodes, the electrodes 41, 42, and 43 constitute second electrodes.

[0088] The piezoelectric element 1 has six piezoelectric layers 5a, 5b, 5c, 5d, 5e, and 5f stacked in a first direction D1. The piezoelectric layer 5a has a main surface 1a. The piezoelectric layer 5f has a main surface 1b. The piezoelectric layers 5b, 5c, 5d, and 5e are located between the piezoelectric layer 5a and the piezoelectric layer 5f. In this embodiment, the piezoelectric layers 5a, 5b, 5c, 5d, 5e, and 5f have the same thickness. In this embodiment, the piezoelectric element PD2 is a so-called stacked piezoelectric element. The external size of the piezoelectric element 1 according to this embodiment is, for example, substantially the same as the external size of the piezoelectric element 1 according to the first embodiment.

[0089] The piezoelectric ceramic material according to this embodiment is, for example, the same as the piezoelectric ceramic material according to Embodiment 1. The piezoelectric ceramic material according to this embodiment is, for example, made of a sintered ceramic green sheet containing the above-described piezoelectric ceramic material.

[0090] In this embodiment, the electrodes 31, 32, and 33 are arranged on the main surface 1a. The electrodes 31, 32, and 33 are arranged in the second direction D2 in the order of electrode 31, electrode 32, and electrode 33. The electrodes 31 and 32 are adjacent to each other in the second direction D2. The electrodes 32 and 33 are adjacent to each other in the second direction D2. In the second direction D2, the shortest distance between the electrodes 32 and 33 is, for example, longer than the shortest distance between the electrodes 31 and 32. For example, voltages of opposite polarities are applied to the electrodes 31, 32, and the electrode 33.

[0091] The electrodes 31, 32, and 33 are spaced apart from all edges (four sides) of the main surface 1a as viewed from the first direction D1. In this embodiment, the electrodes 31, 32, and 33 are rectangular as viewed from the first direction D1. The electrodes 31 and 32 have the same shape as each other as viewed from the first direction D1. As viewed from the first direction D1, the long side directions of the electrodes 31 and 32 coincide with the third direction D3, for example, and the short side directions of the electrodes 31 and 32 coincide with the second direction D2, for example. As viewed from the first direction D1, the long side direction of the electrode 33 coincides with the second direction D2, for example, and the short side direction of the electrode 33 coincides with the third direction D3, for example. The electrodes 31, 32, and 33 contain a conductive material. The conductive material of the electrodes 31, 32, and 33 is the same as the conductive material of the electrodes 11 and 13 according to the first embodiment. The electrodes 31, 32, and 33 are, for example, sintered bodies of conductive paste containing the above-mentioned conductive material.

[0092] Electrodes 31 and 32 may be arranged on principal surface 1a, and electrode 33 may be arranged on principal surface 1b. Electrodes 31 and 32 may be arranged on principal surface 1b, and electrode 33 may be arranged on principal surface 1a. Electrode 31 may be arranged on principal surface 1a, and electrode 32 may be arranged on principal surface 1b. Electrode 31 may be arranged on principal surface 1b, and electrode 32 may be arranged on principal surface 1a.

[0093] The electrodes 41, 42, and 43 are electrically connected to corresponding electrodes 31, 32, and 33 among the plurality of electrodes 31, 32, and 33. In this embodiment, the plurality of electrodes 41 are electrically connected to the electrode 33. The electrode 42 is electrically connected to the electrode 32. The electrode 43 is electrically connected to the electrode 31.

[0094] When viewed from the first direction D1, the electrodes 41, 42, and 43 have, for example, a rectangular shape. When viewed from the first direction D1, the long side direction of the electrodes 41, 42, and 43 coincides with, for example, the third direction D3, and the short side direction of the electrodes 41, 42, and 43 coincides with, for example, the second direction D2.

[0095] The electrodes 41, 42, and 43 are arranged at different positions (layers) in the first direction D1. The electrodes 41, 42, and 43 face each other at an interval in the first direction D1. The electrode 41, the electrode 42, the other electrode 41, the electrode 43, and the further other electrode 41 are, for example, arranged in this order in the first direction D1. The electrodes 41, 42, and 43 are not exposed on the outer surface of the piezoelectric element 1. The electrodes 41, 42, and 43 are not exposed on the main surfaces 1a and 1b. Therefore, the electrodes 41, 42, and 43 are separated from all edges (four sides) of the main surfaces 1a and 1b when viewed from the first direction D1. The electrodes 41, 42, and 43 are not exposed on the side surfaces 1c1, 1c2, 1c3, and 1c4. The electrodes 41, 42, and 43 are spaced apart from all edges (four sides) of the side surfaces 1c1, 1c2, 1c3, and 1c4.

[0096] The electrode 41 is located between the piezoelectric layer 5a and the piezoelectric layer 5b. The electrode 42 is located between the piezoelectric layer 5b and the piezoelectric layer 5c. The other electrode 41 is located between the piezoelectric layer 5c and the piezoelectric layer 5d. The electrode 43 is located between the piezoelectric layer 5d and the piezoelectric layer 5e. A further electrode 41 is located between the piezoelectric layer 5e and the piezoelectric layer 5f. The piezoelectric layer 5a is located between the main surface 1a and the electrode 41. The piezoelectric layer 5b is located between the electrode 41 and the electrode 42. The piezoelectric layer 5c is located between the electrode 42 and the further electrode 41. The piezoelectric layer 5d is located between the further electrode 41 and the electrode 43. The piezoelectric layer 5e is located between the electrode 43 and the further electrode 41. The piezoelectric layer 5f is located between the further electrode 41 and the main surface 1b.

[0097] As shown in FIGS. 13 to 15, at least one of the multiple electrodes 41, 42, and 43 has an electrode region E1 and an electrode region E2. In this embodiment, the multiple electrodes 41, 42, and 43 have an electrode region E1 and an electrode region E2. The electrode region E1 is physically connected to the corresponding electrodes 31, 32, and 33. The electrode region E1 of the electrode 41 is physically connected to the electrode 33. The electrode region E1 of the electrode 42 is physically connected to the electrode 32. The electrode region E1 of the electrode 43 is physically connected to the electrode 31.

[0098] The electrode region E1 covers the element region B1 of the piezoelectric element 1. The electrode region E1 of the electrode 41 covers the element region B1 of the piezoelectric layer 5b. The electrode region E1 of the electrode 42 covers the element region B1 of the piezoelectric layers 5b and 5c. The electrode region E1 of the other electrode 41 covers the element region B1 of the piezoelectric layers 5c and 5d. The electrode region E1 of the electrode 43 covers the element region B1 of the piezoelectric layers 5d and 5e. The electrode region E1 of yet another electrode 41 covers the element region B1 of the piezoelectric layer 5e.

[0099] The electrode region E2 covers an element region B2 that is different from the element region B1. The electrode region E2 of the electrode 41 covers the element region B2 of the piezoelectric layer 5b. The electrode region E2 of the electrode 42 covers the element region B2 of the piezoelectric layers 5b and 5c. The electrode region E2 of the other electrode 41 covers the element region B2 of the piezoelectric layers 5c and 5d. The electrode region E2 of the electrode 43 covers the element region B2 of the piezoelectric layers 5d and 5e. The electrode region E2 of yet another electrode 41 covers the element region B2 of the piezoelectric layer 5e.

[0100] In this embodiment, the range of the percentage of the electrode region E1 covering the element body region B1 is the same as, for example, the range of the percentage of the electrode region E1 covering the element body region B1 in electrodes 21 and 22 according to the first embodiment. The percentage of the electrode region E2 covering the element body region B2 is the same as, for example, the percentage of the electrode region E2 covering the element body region B2 in electrode 21. In this embodiment, the percentage of the electrode region E1 covering the element body region B1 is greater than the percentage of the electrode region E2 covering the element body region B2. In electrodes 41, 42, and 43, the percentage of the electrode region E1 covering the element body region B1 is, for example, 80 to 90%. In electrodes 41, 42, and 43, the percentage of the electrode region E2 covering the element body region B2 is, for example, 70 to 80%.

[0101] The electrode 31 is electrically connected to the electrode 43 and the plurality of connecting conductors 51 by the conductor 61. The conductor 61 is disposed within the piezoelectric element 1. The conductor 61 is physically connected to the electrode region E1 of the electrode 43. In this embodiment, the electrode 31 has the plurality of conductors 61. The plurality of connecting conductors 51 are located on the same layer as the electrode 41, the electrode 42, another electrode 41, and yet another electrode 41, respectively. Each connecting conductor 51 is located in an opening formed in the electrodes 41, 42. Each opening is formed at a position corresponding to the electrode 31 when viewed from the first direction D1. Each connecting conductor 51 is surrounded by the electrodes 41, 42 when viewed from the first direction D1. Each connecting conductor 51 is spaced apart from the electrodes 41, 42. For example, the conductor 61 constitutes a through-hole conductor.

[0102] Each connecting conductor 51 faces an electrode 31 in the first direction D1 and is arranged at a position overlapping with the electrode 31 when viewed from the first direction D1. Each connecting conductor 51 faces an electrode 43 in the first direction D1 and is arranged at a position overlapping with the electrode 43 when viewed from the first direction D1. Each of the plurality of conductors 61 is located between the electrode 31, the electrode 43, and the plurality of connecting conductors 51 and is arranged at a position overlapping with the electrode 31 when viewed from the first direction D1. Each of the plurality of conductors 61 penetrates a corresponding one of the piezoelectric layers 5a, 5b, 5c, 5d, and 5e in the first direction D1.

[0103] The electrode 32 is electrically connected to the electrode 42 and the plurality of connecting conductors 52 by the conductor 62. The conductor 61 is disposed within the piezoelectric element 1. The conductor 61 is physically connected to the electrode region E1 of the electrode 42. In this embodiment, the electrode 32 has a plurality of conductors 62. The plurality of connecting conductors 52 are located on the same layer as the electrodes 41 and 43. Each connecting conductor 52 is located in an opening formed in the electrode 41, another electrode 41, the electrode 43, and another electrode 41. Each opening is formed at a position corresponding to the electrode 32 when viewed from the first direction D1. Each connecting conductor 52 is surrounded by the electrodes 41 and 43 when viewed from the first direction D1. Each connecting conductor 52 is spaced apart from the electrodes 41 and 43. Each connecting conductor 52 is spaced apart from the respective connecting conductors 51. For example, the conductor 62 constitutes a through-hole conductor.

[0104] Each connecting conductor 52 faces an electrode 32 in the first direction D1 and is arranged at a position overlapping with the electrode 32 when viewed from the first direction D1. Each connecting conductor 52 faces an electrode 42 in the first direction D1 and is arranged at a position overlapping with the electrode 42 when viewed from the first direction D1. Each of the multiple conductors 62 is located between the electrode 32, the electrode 42, and the multiple connecting conductors 52 and is arranged at a position overlapping with the electrode 32 when viewed from the first direction D1. Each of the multiple conductors 62 penetrates a corresponding piezoelectric layer 5a, 5b, 5c, 5d, 5e in the first direction D1.

[0105] The connection conductors 51 and 52 located on the same layer as the electrode 41 are positioned adjacent to each other in the same opening. The connection conductors 51 and 52 located on the same layer as another electrode 41 are positioned adjacent to each other in the same opening. The connection conductors 51 and 52 located on the same layer as another electrode 41 are positioned adjacent to each other in the same opening.

[0106] The electrode 33 is electrically connected to the plurality of electrodes 41 and the plurality of connecting conductors 53 by the conductor 63. The conductor 63 is disposed within the piezoelectric element 1. The conductor 63 is physically connected to the electrode region E1 of the electrode 41. In this embodiment, the electrode 33 has the plurality of conductors 63. The plurality of connecting conductors 53 are located on the same layer as the electrodes 42 and 43, respectively. Each connecting conductor 53 is located in an opening formed in the electrodes 42 and 43. Each opening is formed at a position corresponding to the electrode 33 when viewed from the first direction D1. Each connecting conductor 53 is surrounded by the electrodes 42 and 43 when viewed from the first direction D1. Each connecting conductor 53 is spaced apart from the electrodes 42 and 43. For example, the conductor 63 constitutes a through-hole conductor.

[0107] Each connecting conductor 53 faces an electrode 33 in the first direction D1 and is arranged at a position overlapping with the electrode 33 when viewed from the first direction D1. Each connecting conductor 53 faces an electrode 41 in the first direction D1 and is arranged at a position overlapping with the electrode 41 when viewed from the first direction D1. Each of the plurality of conductors 63 is located between the electrode 31, the electrode 41, and the plurality of connecting conductors 53 and is arranged at a position overlapping with the electrode 33 when viewed from the first direction D1. Each of the plurality of conductors 63 penetrates a corresponding one of the piezoelectric layers 5a, 5b, 5c, 5d, and 5e in the first direction D1.

[0108] When viewed from the first direction D1, the connecting conductors 51, 52, and 53 each have, for example, a rectangular shape. When viewed from the first direction D1, the connecting conductors 51 and 52 each have, for example, the same shape as each other. When viewed from the first direction D1, the long side direction of each connecting conductor 51 and 52 coincides with, for example, the third direction D3, and the short side direction of each connecting conductor 51 and 52 coincides with, for example, the second direction D2. When viewed from the first direction D1, the long side direction of the connecting conductor 53 coincides with, for example, the second direction D2, and the short side direction of the connecting conductor 53 coincides with, for example, the third direction D3.

[0109] 13 shows the electrode 41 and the connecting conductors 51 and 52 as viewed from the first direction D1. For ease of understanding, the connecting conductor 53 as viewed from the first direction D1 is added by a dashed line. The electrode 41 includes an electrode region E1 at a position overlapping with the connecting conductor 53 as viewed from the first direction D1.

[0110] 13, when viewed from the first direction D1, the entire outer edge of the connection conductor 53 is located inside the outer edge of the electrode region E1, and the entire outer edge of the conductor 63 is located inside the outer edge of the connection conductor 53. Therefore, when viewed from the first direction D1, the conductor 63 is located entirely inside the electrode region E1 to which the conductor 63 is physically connected. The entire outer edge of the conductor 63 is located inside the outer edge of the electrode region E1. When viewed from the first direction D1, the electrode region E1 extends outside the conductor 63 around the entire periphery of the conductor 63.

[0111] In this embodiment, the electrode region E1 has a circular shape when viewed from the first direction D1. When the conductor 63 has a rectangular shape when viewed from the first direction D1, the circular shape of the electrode region E1 includes the rectangular shape of the conductor 63 and extends to the outside of the rectangular shape of the conductor 63. When the conductor 63 has a circular shape when viewed from the first direction D1, the circular shape of the electrode region E1 includes the circular shape of the conductor 63 and extends to the outside of the circular shape of the conductor 63. In this specification, the term "circular shape" includes, for example, a perfect circle and an ellipse.

[0112] In the electrode 41, the area of ​​the electrode region E1 is, for example, smaller than the area of ​​the electrode region E2. The ratio of the area of ​​the electrode region E1 to the total area of ​​the electrode region E1 and the electrode region E2 is, for example, 1 to 8%.

[0113] 14 shows the electrode 42 and the connecting conductors 51 and 53 as viewed from the first direction D1. For ease of understanding, the connecting conductor 52 as viewed from the first direction D1 is added by a dashed line. The electrode 42 includes an electrode region E1 at a position overlapping with the connecting conductor 52 as viewed from the first direction D1.

[0114] 14, when viewed from the first direction D1, the entire outer edge of the connection conductor 52 is located inside the outer edge of the electrode region E1, and the entire outer edge of the conductor 62 is located inside the outer edge of the connection conductor 52. Therefore, when viewed from the first direction D1, the conductor 62 is located entirely inside the electrode region E1 to which the conductor 62 is physically connected. The entire outer edge of the conductor 62 is located inside the outer edge of the electrode region E1. When viewed from the first direction D1, the electrode region E1 extends outside the conductor 62 around the entire periphery of the conductor 62.

[0115] In the present embodiment, the electrode region E1 has a circular shape when viewed from the first direction D1. When the conductor 62 has a rectangular shape when viewed from the first direction D1, the circular shape of the electrode region E1 includes the rectangular shape of the conductor 62 and extends to the outside of the rectangular shape of the conductor 62. When the conductor 62 has a circular shape when viewed from the first direction D1, the circular shape of the electrode region E1 includes the circular shape of the conductor 62 and extends to the outside of the circular shape of the conductor 62.

[0116] In the electrode 42, the area of ​​the electrode region E1 is, for example, smaller than the area of ​​the electrode region E2. The ratio of the area of ​​the electrode region E1 to the total area of ​​the electrode region E1 and the electrode region E2 is, for example, 0.2 to 5%.

[0117] 15 shows the electrode 43 and the connecting conductors 52 and 53 as viewed from the first direction D1. For ease of understanding, the connecting conductor 51 as viewed from the first direction D1 is added by a dashed line. The electrode 43 includes an electrode region E1 at a position overlapping with the connecting conductor 51 as viewed from the first direction D1.

[0118] 15, when viewed from the first direction D1, the entire outer edge of the connecting conductor 51 is located inside the outer edge of the electrode region E1, and the entire outer edge of the conductor 61 is located inside the outer edge of the connecting conductor 51. Therefore, when viewed from the first direction D1, the conductor 61 is located entirely inside the electrode region E1 to which the conductor 61 is physically connected. The entire outer edge of the conductor 61 is located inside the outer edge of the electrode region E1. When viewed from the first direction D1, the electrode region E1 extends outside the conductor 61 around the entire periphery of the conductor 61.

[0119] In this embodiment, the electrode region E1 has a circular shape when viewed from the first direction D1. When the conductor 61 has a rectangular shape when viewed from the first direction D1, the circular shape of the electrode region E1 includes the rectangular shape of the conductor 61 and extends to the outside of the rectangular shape of the conductor 61. When the conductor 61 has a circular shape when viewed from the first direction D1, the circular shape of the electrode region E1 includes the circular shape of the conductor 62 and extends to the outside of the circular shape of the conductor 61.

[0120] The connecting conductors 51, 52, 53 and the conductors 61, 62, 63 are made of a conductive material. Examples of the conductive material include Ag, Pd, Pt, Cu, and an Ag-Pd alloy. The connecting conductors 51, 52, 53 and the conductors 61, 62, 63 are sintered bodies of a conductive paste containing the above-mentioned conductive material. The conductors 61, 62, 63 are formed by, for example, sintering the conductive paste filled in through holes formed in ceramic green sheets for forming the corresponding piezoelectric layers 5a, 5b, 5c, 5d, 5e.

[0121] In the electrode 43, the area of ​​the electrode region E1 is, for example, smaller than the area of ​​the electrode region E2. The ratio of the area of ​​the electrode region E1 to the total area of ​​the electrode region E1 and the electrode region E2 is, for example, 0.2 to 5%.

[0122] In the piezoelectric element 1, the region of the piezoelectric layer 5b sandwiched between the electrode 41 and the electrode 42, the region of the piezoelectric layer 5c sandwiched between the electrode 42 and the other electrode 41, the region of the piezoelectric layer 5d sandwiched between the other electrode 41 and the electrode 43, and the region of the piezoelectric layer 5e sandwiched between the electrode 43 and the other electrode 41 constitute piezoelectrically active regions. Active regions are formed between the electrode 41 and the electrode 42, between the electrode 42 and the other electrode 41, between the other electrode 41 and the electrode 43, and between the electrode 43 and the other electrode 41. When viewed from the first direction D1, the outer edges of the regions in the piezoelectric layers 5b, 5c, 5d, and 5e where the electrode 41 and the electrode 42, the electrode 42 and the other electrode 41, the other electrode 41 and the electrode 43, and the electrode 43 and the other electrode 41 overlap define boundaries between the active regions and piezoelectrically inactive regions. In the piezoelectric element 1, the piezoelectric layers 5a and 5f form an inactive region.

[0123] The electrodes 41, 42, and 43 are made of a conductive material. The conductive material of the electrodes 41, 42, and 43 according to this embodiment is, for example, the same as the conductive material of the electrodes 21 and 22 according to the first embodiment. The electrodes 41, 42, and 43 are, for example, sintered bodies of a conductive paste containing the above-mentioned conductive material. The electrodes 41, 42, and 43 are formed, for example, by the same formation method as the electrodes 21 and 22. In this embodiment, the configuration in which the coverage ratios of the electrode region E1 and the electrode region E2 are different from each other can be achieved, as in the first embodiment, by controlling the printing conditions when forming the electrode patterns corresponding to the electrodes 41, 42, and 43.

[0124] As described above, the piezoelectric element PD2 according to this embodiment includes the piezoelectric body 1, a plurality of electrodes 31, 32, and 33 arranged on the piezoelectric body 1, and a plurality of electrodes 41, 42, and 43 arranged on the piezoelectric body 1 so as to face each other and electrically connected to corresponding electrodes 31, 32, and 33 among the plurality of electrodes 41, 42, and 43. At least one electrode 41, 42, and 43 of the plurality of electrodes 41, 42, and 43 is physically connected to its corresponding electrode 31, 32, or 33, and has an electrode region E1 covering an element body region B1 of the piezoelectric body 1 and an electrode region E2 covering an element body region B2 of the piezoelectric body 1 that is different from element body region B1. The proportion of electrode region E1 covering element body region B1 is greater than the proportion of electrode region E2 covering element body region B2.

[0125] In piezoelectric element PD2, the proportion of electrode region E1 covering element body region B1 is greater than the proportion of electrode region E2 covering element body region B2. Therefore, electrodes 41, 42, and 43 are less likely to generate heat and less likely to inhibit the displacement of piezoelectric element 1. As a result, piezoelectric element PD1 suppresses deterioration of its displacement characteristics.

[0126] In the piezoelectric element PD2, a plurality of electrodes 41, 42, and 43 have an electrode region E1 and an electrode region E2. In this case, the plurality of electrodes 41, 42, 43 are unlikely to generate heat and are unlikely to hinder the displacement of the piezoelectric body 1. Therefore, the piezoelectric element PD2 is further prevented from deteriorating in its displacement characteristics.

[0127] In the piezoelectric element PD2, the corresponding electrodes 31, 32, and 33 include conductors 61, 62, and 63 arranged in the piezoelectric body 1. The conductors 61, 62, and 63 are physically connected to the electrode region E1. In this case, even if the corresponding electrodes 31, 32, 33 include conductors 61, 62, 63, a configuration in which the conductors 61, 62, 63 are physically connected to the electrode region E1 makes it difficult for the electrodes 41, 42, 43 to generate heat and does not hinder the displacement of the piezoelectric element 1.

[0128] In the piezoelectric element PD2, when viewed from the first direction D1, the conductors 61, 62, and 63 are located entirely inside the electrode region E1 to which the conductors 61, 62, and 63 are physically connected. In this case, the conductors 61, 62, and 63 are reliably connected to the electrode region E1. Therefore, the piezoelectric element PD2 reliably prevents the electrodes 41, 42, and 43 from generating heat, and reliably prevents the displacement of the piezoelectric body 1 from being hindered.

[0129] Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0130] As shown in FIG. 16, the piezoelectric element PD1 includes, for example, a piezoelectric body 1 and an electrode 70. The electrode 70 includes multiple electrodes 70a and 70b. The electrode 70a includes electrodes 71 and 72. The electrode 70b includes a first portion corresponding to the first electrode and a second portion corresponding to the second electrode. For example, if the electrode 71 constitutes the first electrode, the electrode 72 constitutes the second electrode. The electrodes 70a and 70b include, for example, the same material as the electrodes 11, 13, 21, and 22 and are formed by the same method as the electrodes 11, 13, 21, and 22. The piezoelectric body 1 includes, for example, a piezoelectric layer 7. The piezoelectric layer 7 includes, for example, the same material as the piezoelectric layers 3a to 3e. Hatching is omitted in FIG. 16 to clearly show each part.

[0131] The electrode 71 is disposed on, for example, the side surface 1c3. The first portion of the electrode 70b is disposed on, for example, the principal surface 1b. The electrode 72 is disposed on, for example, the principal surface 1a. The electrode 72 is electrically connected to the electrode 71. The electrodes 71 and 72 are continuous with each other. The electrode 71 is spaced apart from the edge of the side surface 1c3 on the principal surface 1b side. The electrode 72 is spaced apart from the edge of the principal surface 1a on the side surface 1c4 side. The second portion of the electrode 70b is electrically connected to the first portion of the electrode 70b. The first and second portions of the electrode 70b are continuous with each other on, for example, the principal surface 1b. The electrode 70b is spaced apart from the edge of the principal surface 1b on the side surface 1c3 side.

[0132] The electrode 72 and the second portion of the electrode 70b have electrode regions E1 and E2. The electrode region E1 of the electrode 72 is continuous with the electrode 71. The electrode region E1 of the second portion of the electrode 70b is continuous with the first portion of the electrode 70b. The electrode region E1 of the electrode 72 and the electrode region E1 of the second portion of the electrode 70b cover the element body region B1. When viewed from the first direction D1, the element body region B1 covered by the electrode region E1 of the electrode 72 and the element body region B1 covered by the electrode region E1 of the second portion of the electrode 70b overlap with each other, for example. The electrode region E2 of the electrode 72 and the electrode region E2 of the second portion of the electrode 70b cover the element body region B2. When viewed from the first direction D1, the element body region B2 covered by the electrode region E2 of the electrode 72 and the element body region B2 covered by the electrode region E2 of the second portion of the electrode 70b overlap with each other, for example. The proportion of the electrode region E1 covering the element body region B1 is greater than the proportion of the electrode region E2 covering the element body region B2.

[0133] As shown in FIG. 17, the piezoelectric element PD1 includes, for example, a piezoelectric body 1 and an electrode 80. The electrode 80 includes multiple electrodes 80a and 80b. The electrode 80a includes electrodes 81 and 82. The electrode 80b includes a first portion corresponding to the first electrode and a second portion corresponding to the second electrode. For example, if the electrode 81 constitutes the first electrode, the electrode 82 constitutes the second electrode. The electrodes 80a and 80b include, for example, the same material as the electrodes 11, 13, 21, and 22 and are formed by the same method as the electrodes 11, 13, 21, and 22. The piezoelectric body 1 includes, for example, two piezoelectric layers 9a and 9b. The piezoelectric layers 9a and 9b include, for example, the same material as the piezoelectric layers 3a to 3e. The electrode 82 has the same configuration as the electrodes 21 and 22. Hatching is omitted in FIG. 17 to clearly illustrate each part.

[0134] The electrode 81 is disposed, for example, on the side surface 1c3. The electrode 82 is electrically connected to the electrode 81. The electrode 82 is located between the piezoelectric layer 9a and the piezoelectric layer 9b. The electrodes 81 and 82 are continuous with each other, for example, at the side surface 1c3. The first portion of the electrode 80b is disposed, for example, on the principal surface 1b. The second portion of the electrode 80b is electrically connected to the first portion of the electrode 80b. The second portion of the electrode 80b is disposed, for example, on the principal surface 1b so as to face the electrode 82 with the piezoelectric layer 9b interposed therebetween. The first and second portions of the electrode 80b are continuous with each other, for example. The electrode 80b is spaced from the edge of the principal surface 1b on the side surface 1c3 side. The electrode 82 and the second portion of the electrode 80b have electrode regions E1 and E2. The electrode region E1 of the electrode 82 is continuous with the electrode 81. The electrode area E1 of the second portion of the electrode 80b is continuous with the first portion of the electrode 80b.

[0135] The electrode region E1 of the electrode 82 and the electrode region E1 of the second portion of the electrode 80b cover the element body region B1 of the piezoelectric layer 9b. When viewed from the first direction D1, the element body region B1 covered by the electrode region E1 of the electrode 82 and the element body region B1 covered by the electrode region E1 of the second portion of the electrode 80b overlap each other. The electrode region E2 of the electrode 82 and the electrode region E2 of the second portion of the electrode 80b cover the element body region B2 of the piezoelectric layer 9b. When viewed from the first direction D1, the element body region B2 covered by the electrode region E2 of the electrode 82 and the element body region B2 covered by the electrode region E2 of the second portion of the electrode 80b overlap each other. The proportion of the electrode region E1 that covers the element body region B1 is greater than the proportion of the electrode region E2 that covers the element body region B2.

[0136] In the piezoelectric element PD1, the area of ​​the electrode region E1 does not have to be smaller than the area of ​​the electrode region E2. In a configuration in which the area of ​​the electrode region E1 is smaller than the area of ​​the electrode region E2, as described above, the electrode region E1 tends to inhibit the displacement of the piezoelectric body 1 more than the electrode region E2. Therefore, in a configuration in which the area of ​​the electrode region E1 is smaller than the area of ​​the electrode region E2, the electrodes 21 and 22 do not reliably inhibit the displacement of the piezoelectric body 1. In the piezoelectric element PD1, the portion E3 of the internal electrode region P1 does not have to be wider than the internal electrode region P2. When viewed from the third direction D3, the internal electrode region P2 does not have to be located within the width of the portion E3 of the internal electrode region P1. In a configuration in which the portion E3 of the internal electrode region P1 is wider than the internal electrode region P2 and the internal electrode region P2 is located within the width of the portion E3 of the internal electrode region P1 when viewed from the third direction D3, the piezoelectric element PD1 reliably suppresses heat generation from the electrodes 21 and 22, as described above. In the piezoelectric element PD2, the conductors 61, 62, and 63 do not necessarily have to be located entirely inside the electrode region E1 to which they are physically connected, as viewed from the first direction D1. In a configuration in which the conductors 61, 62, and 63 are located entirely inside the electrode region E1 to which they are physically connected, as viewed from the first direction D1, the conductors 61, 62, and 63 are reliably connected to the electrode region E1, as described above. Therefore, the piezoelectric element PD2 reliably prevents the electrodes 41, 42, and 43 from generating heat and reliably prevents the displacement of the piezoelectric element 1 from being hindered.

[0137] As can be understood from the above description of the embodiments and modifications, the present specification includes disclosure of the following aspects. (Appendix 1) a piezoelectric element; a first electrode disposed on the piezoelectric element; a second electrode disposed on the piezoelectric element and electrically connected to the first electrode; Equipped with The second electrode is a first electrode region physically connected to the first electrode and covering the first element region of the piezoelectric element; a second electrode region covering a second element body region of the piezoelectric element that is different from the first element body region, A piezoelectric element, wherein a proportion of the first electrode region covering the first element body region is greater than a proportion of the second electrode region covering the second element body region. (Appendix 2) A plurality of the second electrodes are provided, the piezoelectric element has a pair of main surfaces facing each other in a direction in which the plurality of second electrodes face each other, and a side surface connecting the pair of main surfaces, at least one second electrode among the plurality of second electrodes is an internal electrode disposed within the piezoelectric element, The internal electrode is a first internal electrode region facing another second electrode of the plurality of second electrodes; a second internal electrode region having one end exposed to the side surface and physically connected to the first electrode and the other end continuous with the first internal electrode region, the second internal electrode region being narrower than the first internal electrode region; 2. The piezoelectric element of claim 1, wherein the first electrode region includes at least the second internal electrode region. (Appendix 3) 3. The piezoelectric element of claim 2, wherein the first electrode region further includes a portion of the first internal electrode region that is continuous with the second internal electrode region. (Appendix 4) the portion of the first internal electrode region is wider than the second internal electrode region; A piezoelectric element as described in Appendix 3, wherein the second internal electrode region is located within the width range of the portion of the first internal electrode region when viewed from a direction perpendicular to the side surface to which the one end of the second internal electrode region is exposed. (Appendix 5) A piezoelectric element as described in Appendix 4, wherein, when viewed from the direction in which the multiple second electrodes face each other, the boundary between the portion of the first internal electrode region and the remainder of the first internal electrode region is arc-shaped. (Appendix 6) 6. The piezoelectric element according to any one of appendixes 2 to 5, wherein the plurality of second electrodes are internal electrodes having the first internal electrode region and the second internal electrode region. (Appendix 7) 7. The piezoelectric element of claim 6, wherein the first electrode regions of the second electrodes overlap each other when viewed from the direction in which the second electrodes face each other. (Appendix 8) 8. The piezoelectric element according to claim 2, wherein the area of ​​the second internal electrode region is smaller than the area of ​​the first internal electrode region. (Appendix 9) the first electrode includes a through-hole conductor disposed in the piezoelectric element; 2. The piezoelectric element of claim 1, wherein the through-hole conductor is physically connected to the first electrode region. (Appendix 10) A plurality of the second electrodes are provided, A piezoelectric element as described in Appendix 9, wherein, when viewed from the direction in which the multiple second electrodes face each other, the through-hole conductor is located entirely inside the first electrode region to which the through-hole conductor is physically connected. (Appendix 11) 11. The piezoelectric element according to any one of claims 1 to 10, wherein the plurality of second electrodes have the first electrode region and the second electrode region. (Appendix 12) 12. The piezoelectric element according to any one of claims 1 to 11, wherein the area of ​​the first electrode region is smaller than the area of ​​the second electrode region. (Appendix 13) a piezoelectric element; a plurality of first electrodes disposed on the piezoelectric element; a plurality of second electrodes arranged on the piezoelectric element body so as to face each other and electrically connected to corresponding first electrodes among the plurality of first electrodes; Equipped with At least one second electrode among the plurality of second electrodes is a first electrode region physically connected to the corresponding first electrode and covering the first element region of the piezoelectric element; a second electrode region covering a second element body region of the piezoelectric element that is different from the first element body region, A piezoelectric element, wherein a proportion of the first electrode region covering the first element body region is greater than a proportion of the second electrode region covering the second element body region. [Explanation of symbols]

[0138] 1…Cyclone element, 1a…Main surface, 1b…Main surface, 1c…Side surface, 11…Electrode, 13…Electrode, 21…Electrode, 22…Electrode, 31…Electrode, 32…Electrode, 33…Electrode, 41…Electrode, 42…Electrode, 43…Electrode, B1…Elemental field, B2…Elemental field, E1…Electrode field, E2…Electrode field, E3…Part, E4…Part, E5…Remnant, ED1…One end, ED2…Other end, ED3…Boundary, P1…Internal electrode field, P2…Internal electrode field, PD1…Cyclone element, PD2…Cyclone element.

Claims

1. a piezoelectric element; a plurality of first electrodes each including an electrode disposed on an outer surface of the piezoelectric element; a plurality of second electrodes arranged on the piezoelectric element body so as to face each other and form piezoelectrically active regions on the piezoelectric element body, the second electrodes being electrically connected to corresponding first electrodes among the plurality of first electrodes; Equipped with At least one second electrode among the plurality of second electrodes is a first electrode region that is physically connected to the corresponding first electrode, has a plurality of voids formed therein, and covers the first element region of the piezoelectric element; a second electrode region in which a plurality of voids are formed and which covers a second element body region of the piezoelectric body that is different from the first element body region, a proportion of the first electrode region covering the first element body region is greater than a proportion of the second electrode region covering the second element body region; A piezoelectric element, wherein the area of ​​the first electrode region is smaller than the area of ​​the second electrode region.

2. The piezoelectric element according to claim 1 , wherein the plurality of second electrodes have the first electrode region and the second electrode region.

3. the piezoelectric element has a pair of main surfaces facing each other in a direction in which the plurality of second electrodes face each other, and a side surface connecting the pair of main surfaces, the at least one second electrode among the plurality of second electrodes is an internal electrode disposed within the piezoelectric element, The internal electrode is a first internal electrode region facing another second electrode of the plurality of second electrodes; a second internal electrode region having one end exposed to the side surface and physically connected to the first electrode and the other end continuous with the first internal electrode region, the second internal electrode region being narrower than the first internal electrode region; The piezoelectric element according to claim 1 , wherein the first electrode region includes at least the second internal electrode region.

4. The piezoelectric element according to claim 3 , wherein the first electrode region further includes a portion of the first internal electrode region that is continuous with the second internal electrode region.

5. the portion of the first internal electrode region is wider than the second internal electrode region; 5. The piezoelectric element of claim 4, wherein the second internal electrode region is located within a width range of the portion of the first internal electrode region when viewed from a direction perpendicular to the side surface to which the one end of the second internal electrode region is exposed.

6. 6. The piezoelectric element according to claim 5, wherein when viewed from the direction in which the plurality of second electrodes face each other, the boundary between the portion of the first internal electrode region and the remainder of the first internal electrode region has an arc shape.

7. 7. The piezoelectric element according to claim 3, wherein an area of ​​the second internal electrode region is smaller than an area of ​​the first internal electrode region.

8. 7. The piezoelectric element according to claim 3, wherein the plurality of second electrodes are internal electrodes having the first internal electrode region and the second internal electrode region.

9. The piezoelectric element according to claim 8 , wherein the first electrode regions of the second electrodes overlap each other when viewed from the direction in which the second electrodes face each other.

10. The piezoelectric element according to claim 8 , wherein an area of ​​the second internal electrode region is smaller than an area of ​​the first internal electrode region.

11. the corresponding first electrode includes a through-hole conductor disposed within the piezoelectric element; The piezoelectric element according to claim 1 or 2, wherein the through-hole conductor is physically connected to the first electrode region.

12. 12. The piezoelectric element of claim 11, wherein, when viewed from a direction in which the plurality of second electrodes face each other, the through-hole conductor is located entirely inside the first electrode region to which the through-hole conductor is physically connected.

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