piezoelectric elements

Abstract

The piezoelectric element of the present invention comprises a laminate, a first internal electrode, a second internal electrode, and a plurality of external electrodes. The laminate has a plurality of piezoelectric layers stacked on top of each other. The laminate has a pair of main faces facing each other in the stacking direction of the plurality of piezoelectric layers, a pair of end faces facing each other in a first direction intersecting the stacking direction, and a pair of side faces facing each other in a second direction intersecting both the stacking direction and the first direction. The first internal electrode and the second internal electrode are disposed within the laminate and are alternately stacked along the stacking direction via the piezoelectric layers. The first internal electrode includes four electrode portions and a connecting portion. The four electrode portions are arranged in two rows in each of the first and second directions. The connecting portion connects a diagonally opposite pair of electrode portions among the four electrode portions. The connecting portion is disposed separately from each of the remaining pair of electrode portions by a first distance. Each of the four electrode portions includes a main electrode portion. The main electrode portion is disposed separately from the end face by a second distance. The main electrode portion is disposed separately from the side face by a third distance. The first distance is longer than each of the second and third distances.

Description

Technical Field

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

[0002] International Publication No. 2007 / 091443 discloses a piezoelectric element used as an actuator for at least bending vibration. This piezoelectric element comprises a laminate consisting of alternating layers of piezoelectric material and internal electrodes, and external electrodes disposed on the outer surface of the laminate. In this piezoelectric element, the internal electrodes have four segmented electrodes and a connecting electrode that connects a pair of diagonally opposite segmented electrodes to each other. This reduces the number of wires connected to the external electrodes and suppresses vibration damping of the piezoelectric element. Summary of the Invention

[0003] One aspect of this disclosure provides a piezoelectric element capable of increasing displacement.

[0004] One aspect of this disclosure relates to a piezoelectric element comprising a laminate, a first internal electrode, a second internal electrode, and a plurality of external electrodes. The laminate comprises a plurality of piezoelectric layers. The laminate has a pair of main faces facing each other in the lamination direction of the plurality of piezoelectric layers, a pair of end faces facing each other in a first direction intersecting the lamination direction, and a pair of side faces facing each other in a second direction intersecting both the lamination direction and the first direction. The first and second internal electrodes are disposed within the laminate and are alternately laminated along the lamination direction via the piezoelectric layers. The first internal electrode comprises four electrode portions and a connecting portion. The four electrode portions are arranged in two rows in each of the first and second directions. The connecting portion connects a diagonally opposite pair of electrode portions among the four electrode portions. The connecting portion is disposed separately from each of the remaining pair of electrode portions by a first distance. Each of the four electrode portions includes a main electrode portion. The main electrode portion is disposed separately from the end face by a second distance. The main electrode portion is disposed separately from the side face by a third distance. The first distance is longer than either the second or the third distance.

[0005] In this piezoelectric element, the first internal electrode has a connecting portion that connects a pair of diagonally opposite electrode portions among the four electrode portions. Therefore, viewed from the stacking direction, the regions in the piezoelectric layer that overlap not only with the four electrode portions but also with the connecting portion become active regions for piezoelectric activity. The regions overlapping with the connecting portion are regions that become nodes of the bending vibration of the piezoelectric element. Nevertheless, if the regions overlapping with the connecting portion become active regions and vibrate, it may hinder the vibration of the active regions caused by the electrode portions. Therefore, in this piezoelectric element, the connecting portion is arranged separately from the remaining pair of electrode portions by a first distance. The first distance is longer than each of the separation distance between the main electrode portion and the end face (i.e., the second distance) and the separation distance between the main electrode portion and the side face (i.e., the third distance). Therefore, compared to the case where the first distance and each of the second and third distances are equal or less, the vibration of the active regions caused by the connecting portion can be suppressed. Thus, the vibration of the active regions caused by the electrode portions is suppressed. Therefore, the displacement can be increased.

[0006] Alternatively, a pair of main electrode portions adjacent to each other in the first direction can be arranged with a fourth distance separating them. Alternatively, the fourth distance can be longer than either the second or third distance. In this case, a sufficient gap can be ensured between the pair of main electrode portions adjacent to each other in the first direction. Therefore, the region in the piezoelectric layer corresponding to this gap becomes a node for bending vibration, thus enabling the piezoelectric element to undergo stable bending vibration.

[0007] Alternatively, the second and third distances can be equal. In this case, the distances from the end face and side face of the piezoelectric element to the active region are the same. Therefore, the displacement balance becomes good. Consequently, the piezoelectric element can be made to bend and vibrate efficiently.

[0008] Alternatively, a pair of adjacent main electrode portions in the second direction can be arranged separated from each other by a fifth distance, which is equal to the second and third distances. In this case, since the fifth distance is shorter than the first distance, it is easier to ensure the size of the active area caused by the electrode portions.

[0009] Another aspect of this disclosure relates to a piezoelectric element comprising a laminate, a first internal electrode, a second internal electrode, and a plurality of external electrodes. The laminate comprises a plurality of piezoelectric layers. The laminate has a pair of main faces facing each other in the lamination direction of the plurality of piezoelectric layers, a pair of end faces facing each other in a first direction intersecting the lamination direction, and a pair of side faces facing each other in a second direction intersecting both the lamination direction and the first direction. The first and second internal electrodes are disposed within the laminate and are alternately laminated along the lamination direction via the piezoelectric layers. The first internal electrode comprises four electrode portions and a connecting portion. The four electrode portions are arranged in two rows in each of the first and second directions. The connecting portion connects a diagonally opposite pair of electrode portions among the four electrode portions. The connecting portion is disposed separately from each of the remaining pairs of electrode portions by a first distance. Each of the four electrode portions includes a main electrode portion. Adjacent pairs of main electrode portions in the second direction are disposed separately from each other by a fifth distance. The first distance is longer than the fifth distance.

[0010] In this piezoelectric element, the first internal electrode has a connecting portion that connects a pair of diagonally opposite electrode portions among the four electrode portions. Therefore, viewed from the stacking direction, the region in the piezoelectric layer that overlaps not only with the four electrode portions but also with the connecting portion becomes an active region for piezoelectric activity. The region overlapping with the connecting portion is a region that becomes a node for the bending vibration of the piezoelectric element. Nevertheless, if the region overlapping with the connecting portion becomes an active region and vibrates, it may hinder the vibration of the active region caused by the electrode portions. Therefore, in this piezoelectric element, the connecting portion is arranged separated from the remaining pair of electrode portions by a first distance. This first distance is longer than the separation distance of a pair of adjacent main electrode portions in the second direction, i.e., a fifth distance. Therefore, compared to the case where the first distance is equal to or less than the fifth distance, the vibration of the active region caused by the connecting portion can be suppressed. Thus, the vibration hindering the active region caused by the electrode portions is suppressed. Therefore, the displacement can be increased.

[0011] Alternatively, the first distance can be more than half but less than one times the width of the connecting portion. In this case, by making the first distance more than half the width of the connecting portion, the active region caused by the connecting portion can be sufficiently separated from the active region caused by the electrode portion. By making the first distance less than one time the width of the connecting portion, the size of the active region caused by the electrode portion can be easily ensured. Attached Figure Description

[0012] Figure 1 This is a perspective view showing a piezoelectric element according to one embodiment.

[0013] Figure 2 It is along Figure 1 A cross-sectional view of line II-II.

[0014] Figure 3 It is along Figure 1 A cross-sectional view of line III-III.

[0015] Figure 4 It is shown Figure 1 An exploded three-dimensional view of a piezoelectric element.

[0016] Figure 5 This is a top view showing the internal electrodes disposed on the piezoelectric layer.

[0017] Figure 6 This is a top view showing the internal electrodes disposed on the piezoelectric layer.

[0018] Figure 7 This is a top view showing the internal electrodes disposed on the piezoelectric layer.

[0019] Figure 8 This is a diagram showing the state in which the connecting electrodes overlap each other. Detailed Implementation

[0020] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Furthermore, in the description of the drawings, the same or equivalent elements will be given the same reference numerals, and repeated descriptions will be omitted.

[0021] Figure 1 This is a perspective view showing a piezoelectric element according to one embodiment. Figure 1 The piezoelectric element 1 shown is used as a piezoelectric actuator. The piezoelectric element 1 has the function of at least bending and vibrating, and moving a driven body, by applying an alternating voltage. The piezoelectric element 1 includes a laminate 2 and multiple external electrodes 4, 5, 6, 7, 8, and 9. The laminate 2 is in the shape of a cuboid. The cuboid shape includes a cuboid shape with chamfered corners and edges, and a cuboid shape with rounded corners and edges. The laminate 2 has a pair of end faces 2a and 2b facing each other, a pair of side faces 2c and 2d facing each other, and a pair of main faces 2e and 2f facing each other.

[0022] The opposing directions D1 of end faces 2a and 2b, the opposing directions D2 of side faces 2c and 2d, and the opposing directions D3 of main faces 2e and 2f intersect each other. In this embodiment, directions D1, D2, and D3 are orthogonal to each other. Direction D1 is the length direction of the laminate 2. Direction D2 is the width direction of the laminate 2. Direction D3 is the thickness direction of the laminate 2. Main faces 2e and 2f are rectangular. The long side direction of main faces 2e and 2f is consistent with direction D1. The short side direction of main faces 2e and 2f is consistent with direction D2.

[0023] A pair of end faces 2a and 2b extend along the width direction (direction D2) of the laminate 2, connecting the side faces 2c and 2d. End faces 2a and 2b also extend along the thickness direction (direction D3) of the laminate 2, connecting the main faces 2e and 2f. Side faces 2c and 2d extend along the length direction (direction D1) of the laminate 2, connecting the end faces 2a and 2b. Side faces 2c and 2d also extend along the thickness direction of the laminate 2, connecting the main faces 2e and 2f. Main faces 2e and 2f extend along the length direction of the laminate 2, connecting the end faces 2a and 2b. Main faces 2e and 2f also extend along the width direction of the laminate 2, connecting the side faces 2c and 2d.

[0024] The width (length in direction D2) of laminate 2 is, for example, 2.5 mm. The length (length in direction D1) of laminate 2 is, for example, 9 mm. The thickness (length in direction D3) of laminate 2 is, for example, 1 mm. The width of laminate 2 is longer than the thickness of laminate 2, but shorter than the length of laminate 2.

[0025] The surfaces 2a, 2b, 2c, 2d, 2e, and 2f of the laminate 2 are, for example, polished surfaces that have been ground by roller grinding. The edge portions 2g between two adjacent surfaces of each of the surfaces 2a, 2b, 2c, 2d, 2e, and 2f are rounded chamfered. Each edge portion 2g is composed of a curved surface. The corner portions 2h between three adjacent surfaces of each of the surfaces 2a, 2b, 2c, 2d, 2e, and 2f are rounded chamfered. Each corner portion 2h is composed of a curved surface. The radius of curvature of the edge portions 2g and the corner portions 2h is, for example, 0.03 mm or more and 0.15 mm or less.

[0026] External electrodes 4, 5, and 6 are disposed on the side surface 2c of the laminate 2. External electrodes 4, 5, and 6 are separated from each other. External electrodes 4, 5, and 6 are arranged in direction D1. External electrode 4 is disposed on the end face 2a side. External electrode 4 is separated from end face 2a. External electrode 5 is disposed on the end face 2b side. External electrode 5 is separated from end face 2b. External electrode 6 is disposed between external electrode 4 and external electrode 5. External electrode 6 is separated from each of external electrode 4 and external electrode 5.

[0027] External electrodes 4, 5, and 6 are identical in shape. Viewed from direction D2, external electrodes 4, 5, and 6 are rectangular. Each external electrode 4, 5, and 6 extends along direction D3 in a manner connecting the main surface 2e and the main surface 2f. Each external electrode 4, 5, and 6 is formed integrally in direction D3 of the side surface 2c. Each external electrode 4, 5, and 6 is also disposed in the ridge portion 2g between the side surface 2c and the main surface 2e, and in the ridge portion 2g between the side surface 2c and the main surface 2f.

[0028] External electrodes 7, 8, and 9 are disposed on the side 2d of the laminate 2. External electrodes 7, 8, and 9 are separated from each other. External electrodes 7, 8, and 9 are arranged in direction D1. External electrode 7 is disposed on the end face 2a side. External electrode 7 is separated from end face 2a. External electrode 8 is disposed on the end face 2b side. External electrode 8 is separated from end face 2b. External electrode 9 is disposed between external electrodes 7 and 8. External electrode 9 is separated from both external electrodes 7 and 8.

[0029] The external electrodes 7, 8, and 9 are identical in shape. Viewed from direction D2, the external electrodes 7, 8, and 9 are rectangular. Each external electrode 7, 8, and 9 extends along direction D3 in a manner connecting the main surface 2e and the main surface 2f. Each external electrode 7, 8, and 9 is formed integrally in direction D3 of the side surface 2d. Each external electrode 7, 8, and 9 is also disposed in the ridge portion 2g between the side surface 2d and the main surface 2e, and in the ridge portion 2g between the side surface 2d and the main surface 2f.

[0030] External electrodes 4 and 7 are opposite to each other along direction D2. Viewed from direction D2, external electrodes 4 and 7 are arranged in an overlapping manner. External electrodes 5 and 8 are opposite to each other along direction D2. Viewed from direction D2, external electrodes 5 and 8 are arranged in an overlapping manner. External electrodes 6 and 9 are opposite to each other along direction D2. Viewed from direction D2, external electrodes 6 and 9 are arranged in an overlapping manner.

[0031] External electrodes 4, 5, 6, 7, 8, and 9 are formed on the sides 2c and 2d, for example, by sputtering. External electrodes 4, 5, 6, 7, 8, and 9 can also be formed by vapor deposition. Examples of film structures constituting external electrodes 4, 5, 6, 7, 8, and 9 include Cr / Ni, NiCu / Ag, SnAg, or Au. The thickness of external electrodes 4, 5, 6, 7, 8, and 9 is, for example, 0.5 μm to 2.5 μm. The length of direction D1 of external electrodes 4, 5, 6, 7, 8, and 9 is, for example, 1 mm to 1.5 mm.

[0032] External electrodes 4, 5, 6, 7, 8, and 9 can also be sintered electrode layers formed by sintering a conductive paste. The conductive paste can be a conductive paste containing a conductive material with Ag as the main component. External electrodes 4, 5, 6, 7, 8, and 9 can also have a plating layer formed by electroplating. Examples of plating layers include Ni / Au plating.

[0033] Figure 2 It is along Figure 1 A cross-sectional view of line II-II. Figure 3 It is along Figure 1 A cross-sectional view of line III-III. Figure 4It is shown Figure 1 An exploded perspective view of a piezoelectric element. (See diagram below.) Figure 4 As shown, the laminate 2 has piezoelectric layers 10-19 stacked along direction D3. The piezoelectric layers 10-19 of the laminate 2 are constructed by stacking along direction D3. The stacking direction of the piezoelectric layers 10-19 is consistent with the relative direction of the main surfaces 2e and 2f. The piezoelectric layers 10-19 are rectangular plates.

[0034] Piezoelectric layers 10 and 19 are disposed at both ends of the stacking direction (direction D3). The outer surface of piezoelectric layer 10 forms main surface 2e. The outer surface of piezoelectric layer 19 forms main surface 2f. Piezoelectric layers 11 to 18 are disposed between piezoelectric layers 10 and 19 along the stacking direction. The thickness (length along direction D3) of each piezoelectric layer 10 and 19 disposed at both ends of the stacking direction is thinner than the thickness (length along direction D3) of each piezoelectric layer 11 to 18 disposed between piezoelectric layers 10 and 19. The thickness of each piezoelectric layer 11 to 18 is, for example, more than 4 times and less than 8 times the thickness of each piezoelectric layer 10 and 19.

[0035] The thickness of piezoelectric layers 10 and 19 is smaller than the radius of curvature of the ridge portion 2g. The radius of curvature of the ridge portion 2g is, for example, greater than 1 times, but less than 5 times, the thickness of each piezoelectric layer 10 and 19. The thickness of piezoelectric layers 10 and 19 is, for example, 0.02 μm or more and 0.03 μm or less. Along the stacking direction, the thickness of piezoelectric layers 11 to 18 is, for example, 0.12 μm or more and 0.2 μm or more. In this embodiment, piezoelectric layers 10 and 19 have the same thickness, but they may also have different thicknesses. Multiple piezoelectric layers 11 to 18 have the same thickness, but they may also have different thicknesses.

[0036] Each piezoelectric layer 10-19 is composed of a piezoelectric ceramic material. Examples of piezoelectric ceramic materials include PZT [Pb(Zr,Ti)O3], PT (PbTiO3), PLZT [(Pb,La)(Zr,Ti)O3], or barium titanate (BaTiO3). Each piezoelectric layer 10-19 is a sintered body comprising a ceramic green sheet containing the piezoelectric ceramic material. In the actual laminate 2, each piezoelectric layer 10-19 is integrated to the point that the boundaries between each piezoelectric layer 10-19 are indistinguishable.

[0037] A piezoelectric element 1 is disposed within a laminate 2 and includes multiple internal electrodes 20, 30A, and 30B for generating multiple active regions in the laminate 2. In the piezoelectric element 1, internal electrodes 30A and 30B serving as first internal electrodes and internal electrodes 20 serving as second internal electrodes are alternately arranged via piezoelectric layers 10 to 19. The first internal electrode can be any one of the internal electrodes 30A and 30B. However, the piezoelectric element 1 needs to have at least one layer of internal electrodes 30A and 30B. The multiple internal electrodes 20, 30A, and 30B are stacked such that a pair of internal electrodes 20 are located at opposite ends in the stacking direction (direction D3).

[0038] In this embodiment, the piezoelectric element 1 includes a plurality of internal electrodes 20, a plurality of internal electrodes 30A, and a plurality of internal electrodes 30B. Specifically, the piezoelectric element 1 includes: five internal electrodes 20 respectively disposed on piezoelectric layers 10, 12, 14, 16, and 18; two internal electrodes 30A respectively disposed on piezoelectric layers 11 and 15; and two internal electrodes 30B respectively disposed on piezoelectric layers 13 and 17.

[0039] Multiple internal electrodes 20 are respectively disposed between piezoelectric layers 10 and 11, 12 and 13, 14 and 15, 16 and 17, and 18 and 19. Multiple internal electrodes 30A are respectively disposed between piezoelectric layers 11 and 12, and 15 and 16. Multiple internal electrodes 30B are respectively disposed between piezoelectric layers 13 and 14, and 17 and 18.

[0040] An internal electrode 30A disposed on piezoelectric layer 11 faces the internal electrode 20 via piezoelectric layer 11 and also via piezoelectric layer 12. An internal electrode 30B disposed on piezoelectric layer 13 faces the internal electrode 20 via piezoelectric layer 13 and also via piezoelectric layer 14. An internal electrode 30A disposed on piezoelectric layer 15 faces the internal electrode 20 via piezoelectric layer 15 and also via piezoelectric layer 16. An internal electrode 30B disposed on piezoelectric layer 17 faces the internal electrode 20 via piezoelectric layer 17 and also via piezoelectric layer 18.

[0041] Each internal electrode 20, 30A, and 30B is made of a conductive material (e.g., Ag / Pd, Pt, Pd, or Cu). Each internal electrode 20, 30A, and 30B is configured as a sintered body comprising a conductive paste containing the aforementioned conductive material.

[0042] Figure 5 This is a top view showing the internal electrodes 20 disposed on the piezoelectric layer 10. (See attached image.) Figure 5 As shown, the internal electrode 20 has a main electrode portion 20a and connecting portions 20b and 20c connecting the main electrode portion 20a and the corresponding external electrodes 6 and 9. The main electrode portion 20a has a rectangular shape with the length direction of the laminate 2 as the length direction of the main electrode portion 20a. The main electrode portion 20a is separated from the end faces 2a and 2b by a distance L1. The main electrode portion 20a is separated from the side faces 2c and 2d by a distance L2. The distances L1 and L2 are, for example, equal. The distances L1 and L2 are, for example, 0.02 mm or more and 0.25 mm or less.

[0043] like Figure 2 As shown, the connecting portion 20b extends from one side of the main electrode portion 20a along the length direction (direction D1) toward the side surface 2c of the laminate 2, and exposes the edge portion 2g between the side surface 2c and the main surface 2e of the laminate 2. The connecting portion 20b is located at the center of the laminate 2 along the length direction (direction D1). The connecting portion 20c extends from the other side of the main electrode portion 20a along the length direction toward the side surface 2d of the laminate 2, and exposes the edge portion 2g between the side surface 2d and the main surface 2e of the laminate 2. The connecting portion 20c is located at the center of the laminate 2 along the length direction.

[0044] Internal electrodes 20 of the same shape as those on piezoelectric layer 10 are also disposed on piezoelectric layers 12, 14, 16, and 18. Each internal electrode 20 and the multiple electrode portions 31, 32, 33, and 34 included in internal electrodes 30A and 30B (see reference) Figure 6 as well as Figure 7 They function as a common electrode through the piezoelectric layers 11 to 18.

[0045] The internal electrodes 20 disposed on piezoelectric layers 12, 14, and 16 have connecting portions 20b exposed on side surface 2c of the laminate 2, and connecting portions 20c exposed on side surface 2d of the laminate 2. The internal electrodes 20 disposed on piezoelectric layer 18 have connecting portions 20b exposed at the ridge portion 2g between side surface 2c and main surface 2f of the laminate 2, and connecting portions 20c exposed at the ridge portion 2g between side surface 2d and main surface 2f of the laminate 2. The connecting portions 20b of each internal electrode 20 are connected to the external electrode 6. The connecting portions 20c of each internal electrode 20 are connected to the external electrode 9. The internal electrodes 20 disposed on piezoelectric layers 10 and 18 are connected to the corresponding external electrodes 6 and 9 at the ridge portion 2g. The internal electrodes 20 disposed on piezoelectric layers 12, 14, and 16 are connected to the external electrodes 6 and 9 at sides 2c and 2d.

[0046] Figure 6 This is a top view showing the internal electrode 30A disposed on the piezoelectric layer 11. (See attached image.) Figure 6As shown, the internal electrode 30A includes four electrode portions 31, 32, 33, and 34, and a connecting portion 35. An internal electrode 30A of the same shape as that on the piezoelectric layer 11 is also disposed on the piezoelectric layer 15.

[0047] Electrode portions 31, 32, 33, and 34 are arranged in a matrix of two columns along directions D1 and D2, respectively. Electrode portions 31 and 33 are arranged along direction D1 on side 2c. Electrode portions 32 and 34 are arranged along direction D1 on side 2d. Electrode portions 31 and 34 are arranged along direction D2 on end face 2a. Electrode portions 32 and 33 are arranged along direction D2 on end face 2b.

[0048] Electrode portions 31, 32, 33, and 34 are each disposed in one of the four segmented regions that divide the piezoelectric layer 11 in two along directions D1 and D2, respectively. Electrode portions 31 and 32 are located diagonally opposite each other. Electrode portions 33 and 34 are located diagonally opposite each other. Electrode portions 31 and 32 are disposed separately on the piezoelectric layer 11. Electrode portions 33 and 34 are connected to each other on the piezoelectric layer 11 via connecting portions 35.

[0049] Electrode portion 31 is disposed on the piezoelectric layer 11 at the corner formed by the end face 2a and the side face 2c of the laminate 2. Electrode portion 31 has a main electrode portion 31a and a connecting portion 31b connecting the main electrode portion 31a and the corresponding external electrode 4. The main electrode portion 31a and the connecting portion 31b are formed integrally. The main electrode portion 31a is generally rectangular and is separated from each end face 2a, 2b and each side face 2c, 2d. The connecting portion 31b extends from the main electrode portion 31a toward the side face 2c and is exposed at the side face 2c.

[0050] The electrode portion 32 is disposed on the piezoelectric layer 11 at a corner that is diagonally opposite to the corner where the electrode portion 31 is disposed, that is, at the corner side formed by the end face 2b and the side face 2d of the laminate 2.

[0051] The electrode portion 32 has a main electrode portion 32a and a connecting portion 32b connecting the main electrode portion 32a and the corresponding external electrode 8. The main electrode portion 32a and the connecting portion 32b are formed integrally. The main electrode portion 32a is generally rectangular and is separated from each end face 2a, 2b and each side face 2c, 2d. The connecting portion 32b extends from the main electrode portion 32a toward the side face 2d and is exposed on the side face 2d.

[0052] Electrode portion 33 is disposed on the piezoelectric layer 11 at the corner formed by the end face 2b and the side face 2c of the laminate 2. Electrode portion 33 has a main electrode portion 33a and a connecting portion 33b connecting the main electrode portion 33a and the corresponding external electrode 5. The main electrode portion 33a and the connecting portion 33b are formed integrally. The main electrode portion 33a is generally rectangular and is separated from each end face 2a, 2b and each side face 2c, 2d. The connecting portion 33b extends from the main electrode portion 33a toward the side face 2c and is exposed at the side face 2c.

[0053] Electrode portion 34 is disposed on piezoelectric layer 11 at a corner diagonally opposite to the corner where electrode portion 33 is disposed, i.e., at the corner formed by end face 2a and side face 2d of laminate 2. Electrode portion 34 has main electrode portion 34a and connecting portion 34b connecting main electrode portion 34a and corresponding external electrode 7. Main electrode portion 34a and connecting portion 34b are formed integrally. Main electrode portion 34a is generally rectangular and is separate from each end face 2a, 2b and each side face 2c, 2d. Connecting portion 34b extends from main electrode portion 34a toward side face 2d and is exposed on side face 2d.

[0054] Each main electrode portion 31a, 34a is disposed apart from end face 2a by a distance L3. Each main electrode portion 32a, 33a is disposed apart from end face 2b by a distance L3. That is, the separation distance between main electrode portion 31a and end face 2a, the separation distance between main electrode portion 32a and end face 2b, the separation distance between main electrode portion 33a and end face 2b, and the separation distance between main electrode portion 34a and end face 2a are all distances L3. These separation distances are, for example, the average value of multiple portions. The distance L3 is, for example, equal to the distance L1. Preferably, the distance L3 is not shorter than the distance L1, and the distance L4 is not shorter than the distance L2.

[0055] Each main electrode portion 31a, 33a is arranged apart from the side 2c by a distance L4. Each main electrode portion 32a, 34a is arranged apart from the side 2d by a distance L4. That is, the separation distance between the main electrode portion 31a and the side 2c, the separation distance between the main electrode portion 32a and the side 2d, the separation distance between the main electrode portion 33a and the side 2c, and the separation distance between the main electrode portion 34a and the side 2d are all distances L4. These separation distances are, for example, the average value of multiple portions. The distance L4 is, for example, equal to the distance L2.

[0056] The main electrode portions 31a and 34a, adjacent to each other in direction D2, are separated by a distance L5. The main electrode portions 32a and 33a, adjacent to each other in direction D2, are also separated by a distance L5. The separation distance between main electrode portions 31a and 34a, and between main electrode portions 32a and 33a, is distance L5. These separation distances are, for example, average values ​​of multiple portions. Distances L3, L4, and L5 are, for example, equal. Distances L3 and L4 are, for example, 0.02 mm or more and 0.25 mm or less. Distance L5 is, for example, 0.05 mm or more and 0.25 mm or less.

[0057] The adjacent main electrode portions 31a and 33a in direction D1 are separated by a distance L6. Similarly, the adjacent main electrode portions 32a and 34a in direction D1 are separated by a distance L6. That is, the separation distance between main electrode portions 31a and 33a, and between main electrode portions 32a and 34a, is distance L6. These separation distances are, for example, the average value of multiple portions. Distance L6 is longer than distances L3, L4, and L5. Distance L6 is, for example, 0.01 mm or more and 0.3 mm or less.

[0058] The connecting portion 35 electrically and physically connects a pair of diagonally opposite electrode portions 33 and 34 out of the four electrode portions 31, 32, 33, and 34. Specifically, the connecting portion 35 electrically and physically connects the main electrode portion 33a of electrode portion 33 to the main electrode portion 34a of electrode portion 34. The connecting portion 35 is separated from each of the remaining pairs of electrode portions 31 and 32 out of the four electrode portions 31, 32, 33, and 34 by a distance L7. The separation distance between the main electrode portion 31a and the connecting portion 35, and the separation distance between the main electrode portion 32a and the connecting portion 35 are both distances L7. These separation distances are, for example, the average values ​​of multiple locations.

[0059] Distance L7 is longer than distances L3, L4, and L5. Distance L7 is more than 1.2 times the length of distances L3, L4, and L5. Distance L7 is more than 1 / 3 but less than 1 times the width L13 of the connecting portion 35. Distance L7 is, for example, more than 0.01 mm and less than 0.3 mm. Distance L7 is the same as distance L6.

[0060] The connecting portion 35 is disposed on the piezoelectric layer 11 at the center of both directions D1 and D2. The connecting portion 35 is disposed between the electrode portion 31 and the electrode portion 32. Viewed from direction D3, the connecting portion 35 extends in a direction inclined relative to both directions D1 and D2. The width L13 of the connecting portion 35 (the length in a direction orthogonal to the extending direction of the connecting portion 35 when viewed from direction D3) is, for example, 1.3 mm or more and 1.8 mm or less. The width L13 is, for example, the average value of multiple portions.

[0061] Viewed from direction D3, the edge of the electrode portion 33 side (near the center in direction D1) of the main electrode portion 31a and the edge of the electrode portion 34 side (near the center in direction D1) of the main electrode portion 32a respectively include a region R1 inclined along the connecting portion 35 relative to direction D1 and direction D2, and a region R2 along direction D2. The length L8 of direction D2 for each main electrode portion 31a, 32a, 33a, and 34a is, for example, 0.89 mm or more and 1.16 mm or less. The length L9 of direction D2 for region R1 is, for example, 0.9 times or more and 1.1 times or less of the length L10 of direction D2 for region R2. The length L9 is, for example, 0.4 mm or more and 0.6 mm or less. L10 is, for example, 0.43 mm or more and 0.63 mm or less. Viewed from direction D3, the edge of the main electrode portion 33a on the electrode portion 31 side (near the center in direction D1) and the edge of the main electrode portion 34a on the electrode portion 32 side (near the center in direction D1) include the area connected to the connecting portion 35 and other areas. The length L11 of the area connected to the connecting portion 35 in direction D2 is, for example, more than 0.6 times and less than 0.8 times the length L12 of the area other than the connecting portion 35 in direction D2. The length L11 is, for example, more than 0.3 mm and less than 0.6 mm. The length L12 is, for example, more than 0.5 mm and less than 0.7 mm.

[0062] The lengths of direction D1 of the connecting portions 20b, 20c, 31b, 32b, 33b, and 34b are, for example, equal to each other, being 0.9mm or more and 1.4mm or less. The lengths of direction D1 of the connecting portions 20b, 20c, 31b, 32b, 33b, and 34b are less than or equal to the lengths of direction D1 of the external electrodes 4, 5, 6, 7, 8, and 9. Therefore, the exposed portions of the internal electrodes are protected by the external electrodes, thus preventing solder used when connecting the external electrodes to the flexible printed circuit board (FPC) from penetrating into the internal electrode side (solder erosion of the internal electrodes).

[0063] Figure 7 This is a top view showing the internal electrode 30B disposed on the piezoelectric layer 13. (See attached image.) Figure 7 As shown, the internal electrode 30B replaces the connection portion 35 (see reference). Figure 6 Unlike the internal electrode 30A, the connecting portion 36 includes a connecting portion 36. The connecting portion 36 electrically and physically connects a pair of diagonally opposite electrode portions 31 and 32 of the four electrode portions 31, 32, 33, and 34 to each other. Specifically, the connecting portion 36 electrically and physically connects the main electrode portion 31a of electrode portion 31 to the main electrode portion 32a of electrode portion 32.

[0064] The connecting portion 36 is separated from each of the remaining pairs of electrode portions 33 and 34 out of the four electrode portions 31, 32, 33, and 34 by a distance L7. The separation distance between the main electrode portion 33a and the connecting portion 36, and the separation distance between the main electrode portion 34a and the connecting portion 36, are both distances L7. These separation distances are, for example, the average values ​​of multiple portions.

[0065] The connecting portion 36 is disposed on the piezoelectric layer 13 at the center of both directions D1 and D2. The connecting portion 36 is positioned between the electrode portion 33 and the electrode portion 34. Viewed from direction D3, the connecting portion 36 extends in a direction inclined relative to both directions D1 and D2. The width of the connecting portion 36 (the length in a direction orthogonal to the extending direction of the connecting portion 36) is, for example, equal to the width L13.

[0066] In the internal electrode 30B, not the main electrode portions 31a and 32a, but rather the main electrode portions 33a and 34a, regions R1 and R2 are included. Specifically, viewed from direction D3, the edge of the electrode portion 31 side (near the center in direction D1) of the main electrode portion 33a and the edge of the electrode portion 32 side (near the center in direction D1) of the main electrode portion 34a respectively include a region R1 inclined along the connecting portion 36 relative to directions D1 and D2, and a region R2 along direction D2. The length L9 of region R1 in direction D2 and the length L10 of region R2 in direction D2 are the same as those of the internal electrode 30A. That is, the length L9 is 0.9 times or more and 1.1 times or less than the length L10. For example, the length L9 is 0.4 mm or more and 0.6 mm or less. For example, the length L10 is 0.43 mm or more and 0.63 mm or less. Viewed from direction D3, the edge of the main electrode portion 31a on the electrode portion 33 side (near the center in direction D1) and the edge of the main electrode portion 32a on the electrode portion 34 side (near the center in direction D1) include the area connected to the connecting portion 36 and other areas. The length L11 of the area connected to the connecting portion 36 in direction D2 is, for example, more than 0.6 times and less than 0.8 times the length L12 of the area not connected to the connecting portion 36 in direction D2. The length L11 is, for example, more than 0.3 mm and less than 0.6 mm. The length L12 is, for example, more than 0.5 mm and less than 0.7 mm.

[0067] In each internal electrode 30A, 30B, multiple connecting portions 31b are respectively connected to the external electrode 4 on side 2c. Multiple electrode portions 31 are electrically connected to each other via the external electrode 4. Multiple connecting portions 32b are respectively connected to the external electrode 8 on side 2d. Multiple electrode portions 32 are electrically connected to each other via the external electrode 8. Multiple connecting portions 33b are respectively connected to the external electrode 5 on side 2c. Multiple electrode portions 33 are electrically connected to each other via the external electrode 5. Multiple connecting portions 34b are respectively connected to the external electrode 7 on side 2d. Multiple electrode portions 34 are electrically connected to each other via the external electrode 7.

[0068] As described above, in the internal electrode 30A, electrode portions 33 and 34 are interconnected via connecting portion 35. In the internal electrode 30B, electrode portions 31 and 32 are interconnected via connecting portion 36. Therefore, all electrode portions 31 and 32 are electrically connected to each other via connecting portion 36, external electrode 4, and external electrode 8. All electrode portions 33 and 34 are electrically connected to each other via connecting portion 35, external electrode 5, and external electrode 7.

[0069] An example of a method for manufacturing piezoelectric element 1 will be described. First, a ceramic paste for forming piezoelectric layers 10-19 and a conductive paste for forming internal electrodes 20, 30A, and 30B are prepared. The ceramic paste includes, for example, the piezoelectric ceramic material described above and an organic carrier. The conductive paste includes, for example, powder of the conductive material described above and an organic carrier. The organic carrier includes a binder and a solvent. The solvent is, for example, an organic solvent.

[0070] Next, a ceramic green sheet is formed using the aforementioned ceramic paste. In this process, for example, the ceramic paste is applied in a sheet form onto a carrier film, and then the sheet-like ceramic paste is dried. This yields a ceramic green sheet. The ceramic paste is applied, for example, using a doctor blade method. Next, multiple internal electrode patterns are formed on the ceramic green sheet using a conductive paste. In this process, for example, the conductive paste is patterned on the ceramic green sheet and then dried. This yields multiple internal electrode patterns. The internal electrode paste is applied, for example, using a screen printing method.

[0071] Next, ceramic green sheets with internal electrode patterns are stacked to form a green laminate. Then, the green laminate is fired. This forms a laminate substrate. Next, the laminate substrate is sheeted. In this process, for example, the laminate substrate is cut into chip shapes using a cutting machine. This yields multiple laminates of a specified size. Next, the laminate is subjected to an R-beveling process. The R-beveling process is, for example, tumbling. This yields a laminate 2 with R-beveled edge portions 2g and corner portions 2h.

[0072] Next, external electrodes 4, 5, 6, 7, 8, and 9 are formed on sides 2c and 2d. In this process, external electrodes 4, 5, 6, 7, 8, and 9 are formed, for example, by sputtering. Then, the laminate 2 is polarized. Thus, the piezoelectric element 1 is completed.

[0073] In the piezoelectric element 1 configured as described above, different voltages are applied to the external electrodes 4, 5, and 6 via wiring components provided on the side 2c. For example, the external electrode 6 is connected to ground, and voltages with a 90° phase shift are applied to the external electrodes 4 and 5 respectively. This generates multiple active regions of piezoelectric activity in the laminate 2. These active regions are formed corresponding to the electrode portions 31, 32, 33, and 34.

[0074] Specifically, viewed from direction D3, the regions in piezoelectric layers 11-18 that overlap with electrode portions 31, 32, 33, and 34 are considered active regions. The regions in piezoelectric layers 11-18 that are between the main electrode portion 31a of electrode portion 31 and the main electrode portion 20a of internal electrode 20, between the main electrode portion 32a of electrode portion 32 and the main electrode portion 20a of internal electrode 20, between the main electrode portion 33a of electrode portion 33 and the main electrode portion 20a of internal electrode 20, and between the main electrode portion 34a of electrode portion 34 and the main electrode portion 20a of internal electrode 20 are considered active regions.

[0075] The piezoelectric element 1 has two resonant modes when driven. The piezoelectric element 1 vibrates by overlapping a longitudinal vibration mode vibrating along direction D1 and a bending vibration mode vibrating along direction D2. In the piezoelectric element 1, for example, the active regions corresponding to electrode portions 31 and 32 and the active regions corresponding to electrode portions 33 and 34 are displaced in the opposite direction along direction D1. That is, one active region extends along direction D1, and the other active region contracts along direction D1. Thus, viewed from direction D3, the piezoelectric element 1 undergoes an S-shaped bending vibration.

[0076] Figure 8 This is a diagram showing the state where the connected electrodes overlap each other. Figure 8 The diagram shows electrode portions 33 and 34 and connecting portion 35 of internal electrode 30A, and electrode portions 31 and 32 and connecting portion 36 of internal electrode 30B. Here, connecting portion 35 is shown positioned further forward than connecting portion 36. Figure 8 As shown, when viewed from direction D3, connecting portion 35 and connecting portion 36 overlap each other. When viewed from direction D3, the regions in piezoelectric layers 11-18 that overlap with connecting portion 35 and connecting portion 36 also become active regions.

[0077] As described above, the internal electrode 30A has a connecting portion 35, and the internal electrode 30B has a connecting portion 36. Therefore, viewed from direction D3, the regions in the piezoelectric layers 11-18 that overlap not only with the main electrode portions 31a, 32a, 33a, and 34a, but also with the connecting portions 35 and 36, become active regions for piezoelectric activity. The regions overlapping with the connecting portions 35 and 36 are regions that become nodes (non-displaced portions) of the bending vibration of the piezoelectric element 1. Nevertheless, if the regions overlapping with the connecting portions 35 and 36 become active regions and vibrate, they may hinder the vibration of the active regions caused by the main electrode portions 31a, 32a, 33a, and 34a.

[0078] In piezoelectric element 1, distance L7 is longer than any of distances L3 and L4. Therefore, compared to cases where distance L7 is equal to or less than any of distances L3 and L4, vibrations in the active region caused by connecting portions 35 and 36 can be suppressed. Consequently, vibrations in the active region caused by the main electrode portions 31a, 32a, 33a, and 34a can be suppressed, thus increasing the displacement.

[0079] Connection portion 35 connects electrode portions 31 and 32 to each other. Connection portion 36 connects electrode portions 33 and 34 to each other. This reduces the number of wires required to connect to the external electrodes 4-9 in order to apply voltage to them. Furthermore, it eliminates the need to provide connecting electrodes for connecting electrode portions 31 and 32, and connecting electrodes for connecting electrode portions 33 and 34, on the outside of the laminate 2. For example, when each of the external electrodes 4-9 is connected with wires, the two sides 2c and 2d are constrained by the wiring members, thus easily hindering the vibration of the piezoelectric element 1. When the connecting electrodes are located on the outside of the laminate 2, they are easily affected by external conductive particles. In particular, when the connecting electrodes are located on the main surfaces 2e and 2f, active regions may be generated due to the connecting electrodes, and the vibration of these active regions may hinder the vibration of the active regions caused by the main electrode portions 31a, 32a, 33a, and 34a.

[0080] As described above, by having connection portions 35 and 36 in the internal electrodes 30A and 30B, the vibration resistance of the piezoelectric element 1 caused by the wiring and connection electrodes can be suppressed, thus further increasing the displacement. In the structure where the internal electrodes 30A and 30B do not have connection portions 35 and 36, the problem of active regions caused by connection portions 35 and 36 is not generated. However, the vibration resistance of the wiring and connection electrodes is not suppressed, resulting in no improvement in the displacement.

[0081] The distance L7 is at least half and less than one time the width L13 of the connecting portions 35 and 36. By ensuring that the distance L7 is at least half the width L13, the active regions caused by the connecting portions 35 and 36 can be sufficiently separated from the active regions caused by the main electrode portions 31a, 32a, 33a, and 34a. By ensuring that the distance L7 is less than one time the width L13 of the connecting portions 35 and 36, the size of the active regions caused by the main electrode portions 31a, 32a, 33a, and 34a can be easily guaranteed.

[0082] A pair of adjacent main electrode portions 31a and 33a in direction D1 are arranged apart from each other by a distance L6. A pair of adjacent main electrode portions 32a and 34a in direction D1 are also arranged apart from each other by a distance L6. The distance L6 is longer than each of the distances L3 and L4. Therefore, sufficient gaps can be ensured between adjacent pairs of main electrode portions 31a and 33a and between adjacent pairs of main electrode portions 32a and 34a. Therefore, the portions of the piezoelectric layers 11 to 18 corresponding to these gaps become nodes for bending vibration, thus enabling the piezoelectric element 1 to bend and vibrate stably.

[0083] A pair of adjacent main electrode portions 31a and 34a in direction D2 are arranged apart from each other by a distance L5. A pair of adjacent main electrode portions 32a and 33a in direction D2 are also arranged apart from each other by a distance L5. The distance L5 is equal to the distances L3 and L4. The distances L3 and L4 are shorter than the distance L1. Therefore, the distance L5 is also shorter than the distance L1. Therefore, it is easy to ensure the size of the active area caused by the main electrode portions 31a, 32a, 33a, and 34a.

[0084] The distance L7 is longer than the distance L5. Therefore, compared to the case where the distances L7 and L5 are equal or less, the vibration of the active region caused by the connecting portions 35 and 36 can be suppressed. Since the vibration of the active region caused by the main electrode portions 31a, 32a, 33a, and 34a is suppressed, the displacement can be increased.

[0085] In the piezoelectric element 1, the end faces 2a and 2b, the side faces 2c and 2d, and the main faces 2e and 2f are all ground surfaces. Compared to the case of a natural surface, these ground surfaces can suppress displacement differences between multiple active regions. This allows the piezoelectric element 1 to bend and vibrate in a well-balanced manner. Consequently, the displacement of the piezoelectric element 1 can be increased.

[0086] Each edge portion 2g of the laminate 2 has a rounded chamfered shape. This suppresses strain concentration during driving at each edge portion 2g. As a result, each edge portion 2g becomes a starting point, suppressing crack formation in the laminate 2. The piezoelectric layers 10 and 19 disposed at the ends of the laminate are piezoelectrically inert layers, hindering displacement. By making the edge portions 2g adjacent to the main surfaces 2e and 2f chamfered, the volume of the piezoelectric layers 10 and 19 that hinder displacement can be reduced. Therefore, the displacement amount can be easily increased.

[0087] In the laminate 2, viewed from direction D3, in the region outside the internal electrodes 20, 30A, and 30B, i.e., near the end faces 2a and 2b and the side faces 2c and 2d, the electric field is formed in a curved manner, winding around the ends of the internal electrodes 30A and 30B relative to the ends of the adjacent internal electrodes 20. The ridge portion 2g has a rounded chamfer shape, so compared to the case of a planar chamfer shape, it is less likely to hinder the winding of such a curved electric field.

[0088] Multiple internal electrodes 20, 30A, and 30B are stacked with a pair of internal electrodes 20 located at opposite ends in the stacking direction (direction D3). That is, the pair of internal electrodes 20 are adjacent to piezoelectric layers 10 and 19. Assuming that the internal electrodes 30A and 30B, including multiple electrode portions 31, 32, 33, and 34, are positioned at the stack ends, the smoothness of the main surfaces 2e and 2f may be reduced due to the multiple electrode portions 31, 32, 33, and 34 when adjacent to piezoelectric layers 10 and 19. In particular, piezoelectric layers 10 and 19 are thinner than the other piezoelectric layers 11 to 18, so the shape of the multiple electrode portions 31, 32, 33, and 34 may be reflected in the main surfaces 2e and 2f. In contrast, the internal electrodes 20 are common electrodes and are integrally provided throughout the piezoelectric layers 10 and 19. Therefore, in the piezoelectric element 1, the reduction in the smoothness of the main surfaces 2e and 2f is suppressed. As a result, it is possible to suppress the displacement difference between multiple active regions and further improve the displacement amount.

[0089] Since a pair of internal electrodes 20 are disposed at both ends in the stacking direction, the leakage of the electric field of the internal electrodes 30A and 30B to the outside of the laminate 2, which would become noise, can be suppressed, as well as noise received from the outside. As a result, the operation of the piezoelectric element 1 can be stabilized.

[0090] The piezoelectric layers 10 and 19 disposed at the ends of the stack are thinner than the piezoelectric layers 11 to 18 disposed between piezoelectric layers 10 and 19. As described above, piezoelectric layers 10 and 19 are piezoelectrically inert layers that impede displacement. Because the piezoelectric layers 10 and 19, which impede displacement, are thin, the amount of displacement can be further increased.

[0091] The radius of curvature of the ridge portion 2g is larger than the thickness of the piezoelectric layers 10 and 19. Therefore, the internal electrode 20, located at the end of the stack, is exposed in the ridge portion 2g and connected to the external electrodes 6 and 9. The ridge portion 2g has a rounded chamfered shape, thus increasing the exposed area of ​​the internal electrode 20 at the end of the stack. Therefore, the connection strength between the internal electrode 20 and the external electrodes 6 and 9 at the end of the stack is improved.

[0092] The embodiments of the present invention have been described above, but the present invention is not necessarily limited to the above embodiments, and various modifications can be made without departing from its spirit.

[0093] In the above embodiment, the method of forming a laminate 2 by stacking piezoelectric layers 10 to 19 is described as an example. However, the number of piezoelectric layers is not limited to this and can be appropriately set according to the design. In the above embodiment, a pair of internal electrodes 20 are disposed at the stacked end, and internal electrodes 30A and 30B may also be disposed. The internal electrodes 30A and 30B may also be exposed at the ridge portion 2g. The thickness of the piezoelectric layers 10 to 19 may also be equal to each other.

Claims

1. A piezoelectric element, wherein, have: A laminate consisting of multiple piezoelectric layers has the following features: a pair of main faces facing each other in the stacking direction of the multiple piezoelectric layers, a pair of end faces facing each other in a first direction intersecting the stacking direction, and a pair of side faces facing each other in a second direction intersecting the stacking direction and the first direction. A first internal electrode and a second internal electrode are disposed within the laminate and are alternately stacked along the stacking direction via the piezoelectric layer; as well as Multiple external electrodes, The first internal electrode includes four electrode portions and a connecting portion. The four electrode portions are arranged in two columns in each of the first and second directions, respectively. The connecting portion connects a diagonally opposite pair of electrode portions to each other among the four electrode portions, and is separately arranged from each of the remaining pairs of electrode portions by a first distance. Each of the four electrode sections includes a main electrode section. The main electrode portion is disposed at a second distance from the end face, and at a third distance from the side face. The first distance is longer than each of the second and third distances. The length of the connecting portion in the direction orthogonal to the extension direction is less than the length of the main electrode portion in the second direction.

2. The piezoelectric element according to claim 1, wherein, The pair of main electrode portions adjacent to each other in the first direction are arranged apart by a fourth distance. The fourth distance is longer than each of the second and third distances.

3. The piezoelectric element according to claim 1 or 2, wherein, The second distance and the third distance are equal to each other.

4. The piezoelectric element according to any one of claims 1 to 3, wherein, In the second direction, a pair of adjacent main electrode portions are arranged apart from each other by a fifth distance. The fifth distance is equal to the second distance and the third distance.

5. A piezoelectric element, wherein, have: A laminate consisting of multiple piezoelectric layers has the following features: a pair of main faces facing each other in the stacking direction of the multiple piezoelectric layers, a pair of end faces facing each other in a first direction intersecting the stacking direction, and a pair of side faces facing each other in a second direction intersecting the stacking direction and the first direction. A first internal electrode and a second internal electrode are disposed within the laminate and are alternately stacked along the stacking direction via the piezoelectric layer; as well as Multiple external electrodes, The first internal electrode includes four electrode portions and a connecting portion. The four electrode portions are arranged in two columns in each of the first and second directions, respectively. The connecting portion connects a diagonally opposite pair of electrode portions to each other among the four electrode portions, and is separately arranged from each of the remaining pairs of electrode portions by a first distance. Each of the four electrode sections includes a main electrode section. In the second direction, a pair of adjacent main electrode portions are arranged apart from each other by a fifth distance. The first distance is longer than the fifth distance. The length of the connecting portion in the direction orthogonal to the extension direction is less than the length of the main electrode portion in the second direction.

6. The piezoelectric element according to any one of claims 1 to 5, wherein, The first distance is more than 1 / 2 and less than 1 times the width of the connecting portion.

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