Piezoelectric element

Abstract

This piezoelectric element is provided with a multilayer body, a conductor layer, an electrode plate and a cover layer. With respect to the multilayer body, a plurality of piezoelectric bodies and a plurality of internal electrodes are stacked upon each other. The conductor layer is connected to the internal electrodes and is positioned along the stacking direction of the multilayer body. The electrode plate is bonded to the conductor layer with a conductive bonding material being interposed therebetween, and is positioned along the stacking direction of the multilayer body. The cover layer covers the conductor layer and the electrode plate. The electrode plate has a plurality of slits which extend in a direction that intersects with the stacking direction. This piezoelectric element has a first void among the electrode plate, the conductor layer and the bonding material.

Description

Technical Field

[0001] The disclosed embodiments relate to piezoelectric elements.

Background Art

[0002] A piezoelectric element including a laminate in which a plurality of piezoelectric bodies and internal electrodes are laminated, a conductor layer located on a side surface of the laminate and connected to the internal electrode, and an electrode plate partially in a width direction joined to the conductor layer via a conductive bonding material is known (see, for example, Patent Document 1). Also, in a piezoelectric element, a structure in which the conductor layer and the electrode plate are covered with a coating layer located on a side surface of the laminate has been proposed (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

[0004] A piezoelectric element according to an aspect of an embodiment includes a laminate, a conductor layer, an electrode plate, and a coating layer. The laminate has a plurality of piezoelectric bodies and internal electrodes laminated thereon. The conductor layer is connected to the internal electrode and is located along the lamination direction of the laminate. The electrode plate is joined to the conductor layer via a conductive bonding material and is located along the lamination direction of the laminate. The coating layer covers the conductor layer and the electrode plate. The electrode plate has a plurality of slits extending in a direction intersecting the lamination direction. The piezoelectric element has a first gap between the electrode plate, the conductor layer, and the bonding material.

Advantages of the Invention

[0005] According to an aspect of the embodiment, the possibility of peeling of the electrode plate covered with the coating layer can be reduced.

Brief Description of the Drawings

[0006] [Figure 1] Figure 1 is a perspective view showing the overall configuration of the piezoelectric element according to this embodiment. [Figure 2] Figure 2 is an enlarged plan view showing an example of the configuration of the electrode plate and its surrounding area according to the embodiment. [Figure 3] Figure 3 is a cross-sectional view taken along the line III-III shown in Figure 2. [Figure 4] Figure 4 is a cross-sectional view taken along the line IV-IV shown in Figure 2. [Figure 5] Figure 5 is a cross-sectional view showing an example of the configuration of the electrode plate and its surrounding area according to another embodiment 1. [Figure 6] Figure 6 is a cross-sectional view showing an example of the configuration of the electrode plate and its surrounding area according to another embodiment 1. [Figure 7] Figure 7 is a cross-sectional view showing an example of the configuration of the electrode plate and its surrounding area according to another embodiment 2. [Figure 8] Figure 8 is a cross-sectional view showing an example of the configuration of the electrode plate and its surrounding area according to another embodiment 2. [Figure 9] Figure 9 is an enlarged plan view showing an example of the configuration of an electrode plate according to another embodiment 3. [Figure 10] Figure 10 is an enlarged plan view showing an example of the configuration of an electrode plate according to another embodiment 4. [Figure 11] Figure 11 is an enlarged plan view showing an example of the configuration of the electrode plate and its surroundings according to another embodiment 5. [Figure 12] Figure 12 is a cross-sectional view taken along the line XII-XII shown in Figure 11. [Figure 13] Figure 13 is a cross-sectional view taken along the line XIII-XIII shown in Figure 11. [Figure 14] Figure 14 is a cross-sectional view showing an example of the configuration of the electrode plate and its surrounding area according to another embodiment 6. [Figure 15] Figure 15 is a cross-sectional view showing an example of the configuration of the electrode plate and its surrounding area according to another embodiment 6. [Figure 16] Figure 16 is an enlarged plan view showing an example of the configuration of the electrode plate and its surroundings according to another embodiment 7. [Figure 17] Figure 17 is a cross-sectional view taken along the arrow XVII-XVII shown in Figure 16. [Figure 18] Figure 18 is a cross-sectional view showing an example of the configuration of an electrode plate according to another Embodiment 8 and its surroundings. [Figure 19] Figure 19 is an enlarged plan view showing an example of the configuration of an electrode plate according to another Embodiment 9 and its surroundings. [Figure 20] Figure 20 is a cross-sectional view taken along the arrow XX-XX shown in Figure 19. [Figure 21] Figure 21 is a cross-sectional view showing an example of the configuration of an electrode plate according to another Embodiment 10 and its surroundings. [Figure 22] Figure 22 is an enlarged plan view showing an example of the configuration of an electrode plate according to another Embodiment 11 and its surroundings. [Figure 23] Figure 23 is a cross-sectional view showing an example of the configuration of an electrode plate according to another Embodiment 12 and its surroundings.

Mode for Carrying Out the Invention

[0007] Hereinafter, embodiments of the piezoelectric element disclosed in the present application will be described with reference to the accompanying drawings. Note that the present disclosure is not limited by the embodiments shown below. Also, the drawings are schematic, and it should be noted that the dimensional relationships between elements, the ratios of each element, etc. may be different from reality. Furthermore, there may be parts where the dimensional relationships and ratios between the drawings are different from each other.

[0008] <Overall Configuration of Piezoelectric Element> First, the overall configuration of the piezoelectric element 1 according to the embodiment will be described with reference to FIG. 1. FIG. 1 is a perspective view showing the overall configuration of the piezoelectric element 1 according to the embodiment.

[0009] As shown in FIG. 1, the piezoelectric element 1 according to the embodiment includes a laminate 10, a pair of conductor layers 20, a pair of electrode plates 40, and a coating layer 50 (see FIGS. 3 and 4). The pair of conductor layers 20 includes a conductor layer 20A and a conductor layer 20B, and the pair of electrode plates 40 includes an electrode plate 40A and an electrode plate 40B. In FIG. 1, for convenience of explanation, the illustration of the coating layer 50, the conductor layer 20B, and the electrode plate 40B is omitted.

[0010] The laminate 10 has a columnar shape. The laminate 10 is, for example, a square columnar (cuboid) shape with a vertical dimension of 0.5 (mm) to 10 (mm), a horizontal dimension of 0.5 (mm) to 10 (mm), and a height of 1 (mm) to 100 (mm). Note that the shape of the laminate 10 is not limited to a square columnar shape, and may be a hexagonal columnar shape, an octagonal columnar shape, a cylindrical shape, or the like.

[0011] The laminate 10 has a piezoelectric body 11, an internal electrode 12, and a planned fracture layer 13. The laminate 10 is formed by laminating the piezoelectric body 11, the internal electrode 12, and the planned fracture layer 13 in a predetermined order along the lamination direction D. In the present disclosure, the lamination direction D of the laminate 10 coincides with the longitudinal direction of the laminate 10.

[0012] The piezoelectric body 11 is made of a piezoelectric material having piezoelectric characteristics, and is, for example, made of piezoelectric ceramics. The material of such piezoelectric ceramics is, for example, a perovskite-type oxide made of lead zirconate titanate (PbZrO3 - PbTiO3), lithium niobate (LiNbO3), or lithium tantalate (LiTaO3).

[0013] The average particle size of such piezoelectric ceramics is, for example, 1.6 (μm) to 2.8 (μm). The thickness of the piezoelectric body 11 is, for example, 3 (μm) to 250 (μm).

[0014] The internal electrode 12 is made of a conductive material and includes a plurality of first electrodes 12a and a plurality of second electrodes 12b. The first electrode 12a is electrically connected to the conductor layer 20A disposed on one side surface 10a of the laminate 10. A predetermined positive voltage is applied to the first electrode 12a through such a conductor layer 20A.

[0015] The second electrode 12b is electrically connected to a conductor layer 20B located on the side 10b of the laminate 10 opposite to the side 10a. A predetermined negative voltage (or ground voltage) is applied to the second electrode 12b via the conductor layer 20B.

[0016] Inside the laminate 10, the first electrode 12a, the second electrode 12b, and the piezoelectric element 11 are stacked such that the piezoelectric element 11 is positioned between the first electrode 12a and the second electrode 12b. This allows the laminate 10 to apply a driving voltage to the piezoelectric element 11 using the first electrode 12a and the second electrode 12b.

[0017] Furthermore, the laminate 10 according to the embodiment is composed of an active portion formed by alternately stacking a plurality of piezoelectric bodies 11 and internal electrodes 12, and an inactive portion having a piezoelectric body 11, which is arranged at both ends of the stacking direction D in the active portion.

[0018] The active portion is the part that expands or contracts (hereinafter also referred to as "expansion or contraction") in the lamination direction D when a driving voltage is applied to the laminate 10 from the outside. On the other hand, the inactive portion is the part that does not expand or contract even when a driving voltage is applied to the laminate 10 from the outside.

[0019] Furthermore, in this disclosure, the lower end of Figure 1 is defined as the base end 10e of the laminate 10, and the upper end of Figure 1 is defined as the tip end 10f of the laminate 10.

[0020] In the piezoelectric element 1 according to this embodiment, the base end portion 10e of the laminate 10 is fixed, and the tip portion 10f of the laminate 10 is displaced along the lamination direction D.

[0021] The material of the internal electrode 12 is a metal mainly composed of, for example, silver, silver-palladium, silver-platinum, or copper. The internal electrode 12 can be formed, for example, by co-firing with the piezoelectric body 11. The thickness of the internal electrode 12 is, for example, 0.1 (μm) to 5 (μm).

[0022] The pre-fractured layer 13 is a layer that relieves the stress generated by the driving of the laminate 10. Examples of the pre-fractured layer 13 include a porous metal layer that does not function as an internal electrode 12, or a metal layer that has pre-cracked. In the laminate 10 according to this embodiment, the pre-fractured layer 13 may be omitted.

[0023] The pair of conductive layers 20, as described above, include a conductive layer 20A located on side surface 10a of the laminate 10 and a conductive layer 20B located on side surface 10b of the laminate 10. The conductive layers 20 are arranged to extend across the entire active portion of the laminate 10. The conductive layers 20 are located along the lamination direction D.

[0024] The material of the conductive layer 20 is, for example, a metal mainly composed of silver or copper. For example, a metallized layer made of a sintered body of the above-mentioned metal and glass can be used for the conductive layer 20. The thickness of the conductive layer 20 is, for example, 5 (μm) to 500 (μm).

[0025] The pair of electrode plates 40 includes electrode plate 40A and electrode plate 40B, and are electrically connected to a pair of conductor layers 20, respectively. Specifically, electrode plate 40A is electrically connected to conductor layer 20A, and electrode plate 40B is electrically connected to conductor layer 20B.

[0026] The electrode plate 40 is positioned along the lamination direction D of the laminate 10. A portion of the electrode plate 40 in the width direction intersecting the lamination direction D is bonded to the conductor layer 20 via a conductive bonding material 30. As such bonding material 30, for example, epoxy resin or polyimide resin containing highly conductive metal powder such as Ag powder or Cu powder is used.

[0027] The electrode plate 40 is made of a metal such as copper, iron, stainless steel, or phosphor bronze. The width of the electrode plate 40 is, for example, 0.5 mm to 10 mm, and the thickness of the electrode plate 40 is, for example, 0.01 mm to 1.0 mm. The surface of the electrode plate 40 may be coated with a plating film such as tin plating or silver plating to improve electrical and thermal conductivity.

[0028] The coating layer 50 is located around the entire circumference of the side surface 10a and side surface 10b of the laminate 10, and covers the conductor layer 20 and the electrode plate 40. By arranging the coating layer 50 on the side surfaces 10a and 10b, surface discharge between the two electrodes that occurs when a high voltage is applied during operation can be reduced.

[0029] The coating layer 50 is composed of, for example, an insulator. Examples of insulators that make up this coating layer 50 include fluororesins, silicone resins, epoxy resins, and nylon resins.

[0030] Furthermore, the coating layer 50 only needs to be located on at least the sides 10a and 10b of the laminate 10 so as to cover the conductor layer 20 and the electrode plate 40, and does not necessarily need to be placed around the entire circumference of the sides. For example, the coating layer 50 may not be placed on the sides 10c and 10d of the laminate 10, but only on the sides 10a and 10b.

[0031] <Configuration of electrode plate and coating layer> Next, the detailed configuration of the electrode plate 40 and the coating layer 50 according to the embodiment will be described with reference to Figures 2 to 4. Figure 2 is an enlarged plan view showing an example of the configuration of the electrode plate 40 and its surroundings according to the embodiment. Figure 3 is a cross-sectional view taken along the line III-III shown in Figure 2. Figure 4 is a cross-sectional view taken along the line IV-IV shown in Figure 2. Note that, for the sake of explanation, the coating layer 50 is not shown in Figure 2.

[0032] As described above, the electrode plate 40 is a plate-shaped member extending in the stacking direction D of the laminate 10, and a portion of the width direction intersecting the stacking direction D is joined to the conductor layer 20 via a conductive bonding material 30.

[0033] As shown in Figure 2, in this embodiment, the electrode plate 40 has a plurality of slits S. These slits S are cut out, for example, so as to extend along the width direction of the electrode plate 40 (i.e., the direction intersecting the stacking direction D).

[0034] Multiple slits S are alternately cut out from the end faces of both ends of the electrode plate 40 that are located outside the bonding material 30 in a plan view in the width direction, and are arranged at approximately equal intervals along the stacking direction D. Furthermore, all of the multiple slits S have approximately equal lengths. The length of a slit S refers to its length in the direction of the cutout (i.e., in the width direction of the electrode plate 40).

[0035] Furthermore, the lengths of multiple slits S are set so that their tips overlap when viewed in the stacking direction D. Here, overlapping means that, when viewed in the stacking direction D, adjacent slits S have regions that face each other.

[0036] In this embodiment, by arranging multiple slits S in the electrode plate 40, the electrode plate 40 can be made to expand and contract in the stacking direction D in accordance with the expansion and contraction of the laminate 10 in the stacking direction D. Therefore, according to this embodiment, the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20 can be reduced.

[0037] On the other hand, the electrode plate 40 is covered together with the conductor layer 20 by a coating layer 50 (see Figures 3 and 4) located on the side surface of the laminate 10.

[0038] If the electrode plate 40 and the conductor layer 20 are completely covered with the coating layer 50, a large stress will be generated in the electrode plate 40 that limits its deformation when the laminate 10 expands and contracts. In particular, a stress that limits torsional deformation will be concentrated at the end of the electrode plate 40 that is located outside the joining material 30 in the width direction in a plan view. As the electrode plate 40 expands and contracts, the stress that limits its deformation will be generated in the electrode plate 40, which may cause the electrode plate 40 to delaminate from the laminate 10 or the conductor layer 20.

[0039] Therefore, in this embodiment, as shown in Figures 3 and 4, the conductor layer 20 and the electrode plate 40 are covered with the coating layer 50 while leaving a gap G between the end of the electrode plate 40 located outside the bonding material 30 in the width direction in a plan view and the conductor layer 20. In other words, in this embodiment, the piezoelectric element 1 has a gap G between the electrode plate 40, the conductor layer 20 and the bonding material 30. Multiple such gaps G are formed in positions that do not overlap with the multiple slits S of the electrode plate 40 in a plan view (see Figure 2). The end of the electrode plate 40 located outside the bonding material 30 in the width direction in a plan view and the conductor layer 20 are positioned facing each other with each gap G in between. The gap G is an example of a first gap.

[0040] In this embodiment, by covering the conductor layer 20 and electrode plate 40 with the covering layer 50 while such void G remains, torsional deformation occurs at the widthwise ends of the electrode plate 40 in accordance with the expansion and contraction of the laminate 10 in the lamination direction D, making the electrode plate 40 easier to deform. Therefore, according to this embodiment, the stress generated in the electrode plate 40 due to the expansion and contraction of the laminate 10 can be alleviated, thereby reducing the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20.

[0041] Furthermore, in this embodiment, as shown in Figures 2 and 3, the air gap G between one end of the electrode plate 40 located outside the bonding material 30 in the width direction in a plan view and the conductor layer 20, and the air gap G between the other end of the electrode plate 40 and the conductor layer 20 are separated. That is, the air gap G between one end of the electrode plate 40 and the conductor layer 20 and the air gap G between the other end of the electrode plate 40 and the conductor layer 20 are not connected and are individually closed with the bonding material 30 as the boundary. By separating the air gap G on one end side of the electrode plate 40 from the air gap G on the other end side, torsional deformation can be more easily generated at both ends of the electrode plate 40 in the width direction in response to expansion and contraction of the laminate 10 in the lamination direction D. Therefore, according to this embodiment, the stress generated in the electrode plate 40 due to the expansion and contraction of the laminate 10 can be more easily relieved, and thus the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20 can be further reduced.

[0042] Furthermore, in this embodiment, as shown in Figure 2, the air gap G between one end of the electrode plate 40 and the conductor layer 20, and the air gap G between the other end of the electrode plate 40 and the conductor layer 20 are located at positions offset from each other in the lamination direction D of the laminate 10. This makes it easier for torsional deformation to occur at both ends of the electrode plate 40 in the width direction in accordance with the expansion and contraction of the laminate 10 in the lamination direction D. Therefore, according to this embodiment, the stress generated in the electrode plate 40 due to the expansion and contraction of the laminate 10 can be further reduced, thereby further reducing the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20.

[0043] Furthermore, in this embodiment, as shown in Figure 2, the bonding material 30 may be positioned to overlap with the central portion of the electrode plate 40 in a plan view. This makes it possible to make the gap G on one end of the electrode plate 40 separated by the bonding material 30 and the gap G on the other end substantially the same size, and torsional deformation occurs evenly at both ends of the electrode plate 40 in the width direction in accordance with the expansion and contraction of the laminate 10 in the lamination direction D. Therefore, according to this embodiment, the stress generated in the electrode plate 40 due to the expansion and contraction of the laminate 10 can be evenly relieved at both ends of the electrode plate 40 in the width direction, thereby further reducing the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20.

[0044] Furthermore, in this embodiment, as shown in Figure 2, the bonding material 30 may have a region that overlaps with the slit S of the electrode plate 40 in a plan view. This makes it less likely for the electrode plate 40 to peel off from the bonding material 30 near the slit S of the electrode plate 40.

[0045] Furthermore, in this embodiment, the length of the slit S in the electrode plate 40 is greater than half the width of the electrode plate 40. As a result, the position of the tip of the slit S in the notch direction, which is the starting point of the twist that occurs at the widthwise end of the electrode plate 40, is offset from the position of the bonding material 30 located in the central part of the electrode plate 40, making it difficult for the electrode plate 40 to peel off from the bonding material 30.

[0046] <Another Embodiment 1> Next, various other embodiments will be described with reference to Figures 5 to 23. In the various other embodiments shown below, the same reference numerals are used for parts that are the same as in the embodiments, and redundant explanations may be omitted.

[0047] Figures 5 and 6 are cross-sectional views showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 1. Figure 5 corresponds to the cross-sectional view taken along the line III-III in Figure 2, and Figure 6 corresponds to the cross-sectional view taken along the line IV-IV in Figure 2.

[0048] In the other embodiment 1 shown in Figures 5 and 6, the configuration of the coating layer 50 differs from that of the embodiment described above. Specifically, in the other embodiment 1, as shown in Figure 5, the coating layer 50 has an overhang 51. The overhang 51 is located inward from the edge of the electrode plate 40 in the direction intersecting the lamination direction D (i.e., the width direction) and is in contact with the conductor layer 20. Here, "inward" means the side toward the center of the electrode plate 40. The overhang 51 is an example of a first overhang.

[0049] In another embodiment 1, by providing an overhang 51 on the coating layer 50, the adhesion between the coating layer 50 and the conductor layer 20 is improved compared to the case where the overhang 51 is not provided. Therefore, the adhesion between the electrode plate 40 covered by the coating layer 50 and the conductor layer 20 is improved. Accordingly, according to this other embodiment 1, the possibility of the electrode plate 40 covered by the coating layer 50 peeling off from the conductor layer 20 can be reduced.

[0050] In another embodiment 1, as shown in Figure 6, the coating layer 50 may have an overhang 52. The overhang 52 is positioned to protrude inward from the inner wall surface of the slit S in the electrode plate 40 and is in contact with the conductor layer 20. Here, "inward" means the side that is closer to the center of each electrode plate. The overhang 52 is an example of a second overhang.

[0051] By providing the protruding portion 52 in the coating layer 50, the adhesion between the coating layer 50 and the conductor layer 20 is improved compared to the case where the protruding portion 52 is not provided, and thus the adhesion between the electrode plate 40 covered by the coating layer 50 and the conductor layer 20 is improved. Therefore, according to the other embodiment 1, the possibility of the electrode plate 40 covered by the coating layer 50 peeling off from the conductor layer 20 can be reduced.

[0052] <Another Embodiment 2> Figures 7 and 8 are cross-sectional views showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 2. Figure 7 corresponds to the cross-sectional view taken along the line III-III in Figure 2, and Figure 8 corresponds to the cross-sectional view taken along the line IV-IV in Figure 2.

[0053] In another embodiment 2 shown in Figures 7 and 8, the configuration of the electrode plate 40 is the same as in the other embodiment described above. 1 This differs from the previous embodiment 2. Specifically, as shown in Figure 7, the electrode plate 40 has a protrusion 41 that rises in the thickness direction of the electrode plate 40 at the periphery of the end of the electrode plate 40 in the direction intersecting the stacking direction D (i.e., the width direction). The protrusion 41 is an example of the first protrusion.

[0054] In another embodiment 2, by providing the protrusions 41 on the electrode plate 40, the strength of both ends of the electrode plate 40 is increased compared to the case where the protrusions 41 are not provided, making it less likely for damage to both ends of the electrode plate 40 to occur due to repeated deformation. Therefore, according to another embodiment 2, the durability of the electrode plate 40 can be improved. In Figure 7, the protrusions 41 are located on the laminate 10 side and on the opposite side of the laminate 10, but they may be located only on the laminate 10 side.

[0055] Furthermore, in another embodiment 2, the thickness of the protruding portion 51 of the coating layer 50 located near the protrusion 41 is reduced by the thickness of the protrusion 41, making it easier to deform the electrode plate 40 in accordance with the expansion and contraction of the laminate 10 in the lamination direction D. Therefore, according to another embodiment 2, the stress generated in the electrode plate 40 due to the expansion and contraction of the laminate 10 can be further reduced, thereby further reducing the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20.

[0056] Furthermore, in another embodiment 2, the protrusion 41 may extend along the stacking direction D of the laminate 10. This increases the strength of both ends of the electrode plate 40, making it less susceptible to damage to both ends of the electrode plate 40 due to repeated deformation. Therefore, according to another embodiment 2, the durability of the electrode plate 40 can be further improved.

[0057] In another embodiment 2, as shown in Figure 8, the electrode plate 40 may have a protrusion 42 that rises in the thickness direction of the electrode plate 40 on the periphery of the slit S in the electrode plate 40. The protrusion 42 is an example of a second protrusion.

[0058] By providing the protrusions 42 on the electrode plate 40, the strength of the periphery of the slit S in the electrode plate 40 is increased compared to the case where the protrusions 42 are not provided, making it less likely for damage to the periphery of the slit S in the electrode plate 40 to occur due to repeated deformation. Therefore, according to the other embodiment 2, the durability of the electrode plate 40 can be improved. In Figure 8, the protrusions 42 are located on the laminate 10 side and on the opposite side of the laminate 10, but they may be located only on the laminate 10 side.

[0059] Furthermore, in another embodiment 2, the thickness of the protruding portion 52 of the coating layer 50 located near the protrusion 42 is reduced by the thickness of the protrusion 42, making it easier to deform the electrode plate 40 in accordance with the expansion and contraction of the laminate 10 in the lamination direction D. Therefore, according to another embodiment 2, the stress generated in the electrode plate 40 due to the expansion and contraction of the laminate 10 can be further reduced, thereby further reducing the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20.

[0060] Furthermore, in another embodiment 2, the protrusion 42 may extend along the longitudinal direction of the slit S. This increases the strength of the periphery of the slit S in the electrode plate 40, making it less likely for damage to the periphery of the slit S in the electrode plate 40 to occur due to repeated deformation. Therefore, according to another embodiment 2, the durability of the electrode plate 40 can be further improved.

[0061] The formation of the protrusions 41 and 42 can be achieved by etching the side surface of the metal plate 40a (see Figure 7), which serves as the base material for the electrode plate 40, to form recesses, and then plating the corners located around the periphery of the recesses with a thicker layer than other areas.

[0062] <Other Embodiment 3> Figure 9 is an enlarged plan view showing an example of the configuration of the electrode plate 40 according to another embodiment 3. In the other embodiment 3 shown in Figure 9, the shape of the electrode plate 40 differs from that of the embodiment described above. Specifically, in the other embodiment 3, the electrode plate 40 has a plurality of slits S and a plurality of through holes H.

[0063] Such slits S are formed, for example, along the width direction of the electrode plate 40 (i.e., the direction intersecting the stacking direction D), extending to the end face of either end of the electrode plate 40. The through holes H are formed to extend along the same direction as the slits S, but do not extend to the end faces of either end of the electrode plate 40.

[0064] Multiple slits S are alternately cut out from the end faces of both ends of the electrode plate 40 in the width direction and are arranged at approximately equal intervals along the stacking direction D. All of the multiple slits S have approximately equal lengths. The lengths of the multiple slits S are set so that their ends overlap when viewed in the stacking direction D.

[0065] In another embodiment 3, by arranging multiple slits S in the electrode plate 40, the electrode plate 40 can be made to expand and contract in the stacking direction D in accordance with the expansion and contraction of the laminate 10 in the stacking direction D. Therefore, according to another embodiment 3, the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20 can be reduced.

[0066] Furthermore, in another embodiment 3, through holes H are located between slits S that are alternately cut out from the end faces of both ends in the width direction of the electrode plate 40. Such through holes H are positioned at equal intervals with respect to both adjacent slits S and have a length approximately equal to the length of the slits S.

[0067] In other words, in the third embodiment, as shown in Figure 9, in the electrode plate 40, a slit S and a through hole H extending from the end face of one end, and a slit S and a through hole H extending from the end face of the other end are arranged in this order along the stacking direction D at substantially equal intervals.

[0068] In another embodiment 3, a through hole H is positioned at the point where the tips of a slit S extending from the end face of one end and a slit S extending from the end face of the other end overlap.

[0069] This allows the stress generated between the slit S extending from the end face of one end and the slit S extending from the end face of the other end to be distributed, thereby mitigating the stress generated in the electrode plate 40 due to the expansion and contraction of the laminate 10. Therefore, according to the other embodiment 3, the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20 can be further reduced.

[0070] <Other Embodiments 4> Figure 10 is an enlarged plan view showing an example of the configuration of the electrode plate 40 according to another embodiment 4. In the other embodiment 4 shown in Figure 10, the arrangement of the through holes H differs from that of the other embodiment 3 described above.

[0071] Specifically, in another embodiment 4, in the electrode plate 40, two or more through holes H are located adjacent to each other between slits S that are alternately cut out from the end faces of both ends in the width direction.

[0072] For example, as shown in Figure 10, in the electrode plate 40, a slit S extending from the end face of one end, a through hole H, a through hole H, and a slit S extending from the end face of the other end are arranged in this order at approximately equal intervals along the stacking direction D.

[0073] In this way, by arranging two or more through holes H adjacent to each other between slits S that are alternately cut out from the end faces of both ends in the width direction of the electrode plate 40, the stress generated in the electrode plate 40 due to the expansion and contraction of the laminate 10 can be further relieved. Therefore, according to the other embodiment 4, the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20 can be further reduced.

[0074] <Another Embodiment 5> Figure 11 is an enlarged plan view showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 5. Figure 12 is a cross-sectional view taken along the line XII-XII shown in Figure 11. Figure 13 is a cross-sectional view taken along the line XIII-XIII shown in Figure 11. Note that, for the sake of explanation, the coating layer 50 is not shown in Figures 11 to 13.

[0075] In the other embodiment 5 shown in Figures 11 to 13, the configuration of the electrode plate 40 and the addition of a fixing material 60 differ from the above-described embodiment. Specifically, in the other embodiment 5, as shown in Figure 11, the electrode plate 40 is a plate-shaped member extending in the stacking direction D of the laminate 10, and has a main body portion 43 joined to the conductor layer 20 via a conductive bonding material 30, and a protruding portion 44 that protrudes from one end 43a of the main body portion 43 in the stacking direction D and faces the laminate 10.

[0076] The main body portion 43 has a first portion 431 that is in contact with the bonding material 30, and a second portion 432 located on both sides of the first portion 431 in the width direction (i.e., the direction intersecting the lamination direction D), which faces the conductor layer 20 without being in contact with the bonding material 30.

[0077] As shown in Figure 11, in another embodiment 5, the main body 43 of the electrode plate 40 has a plurality of slits S. These slits S are cut out, for example, so as to extend along the width direction of the main body 43 (i.e., the direction intersecting the stacking direction D).

[0078] Multiple slits S are alternately cut out from both sides of the main body 43 (i.e., the sides of the pair of second parts 432) and are arranged at approximately equal intervals along the stacking direction D. Furthermore, all of the multiple slits S have approximately equal lengths. The length of a slit S refers to its length in the direction of its cutout (i.e., the width direction of the main body 43).

[0079] Furthermore, the lengths of multiple slits S are set so that their tips overlap when viewed in the stacking direction D. Here, overlapping means that, when viewed in the stacking direction D, adjacent slits S have regions that face each other.

[0080] In another embodiment 5, by arranging a plurality of slits S in the main body portion 43 of the electrode plate 40, the main body portion 43 can be made to expand and contract in the stacking direction D in accordance with the expansion and contraction of the laminate 10 in the stacking direction D. Therefore, according to another embodiment 5, the possibility of the electrode plate 40 peeling off from the laminate 10 or the conductor layer 20 can be reduced.

[0081] The protruding portion 44 of the electrode plate 40 faces the laminate 10 across the first void G1.

[0082] Furthermore, the piezoelectric element 1 according to another embodiment 5 includes a fixing material 60. The fixing material 60 fixes the electrode plate 40 and the laminate 10. For example, the fixing material 60 fixes at least the protruding portion 44 of the electrode plate 40 to the laminate 10.

[0083] In addition, the fixing material 60 according to the other embodiment 5 does not necessarily have to fix the entire circumference of the periphery of the protruding portion 44 to the laminate 10. In short, it is sufficient that at least a part of the periphery of the protruding portion 44 is fixed to the laminate 10 by the fixing material 60.

[0084] Furthermore, in the other embodiment 5, the fixing material 60 may be fixed to the laminate 10 around the entire circumference of the periphery of the protruding portion 44, while a predetermined region surrounded by the periphery of the protruding portion 44 remains on the protruding portion 44. This allows the predetermined region remaining on the protruding portion 44 to be used as a region for joining lead terminals that supply power to the electrode plate 40.

[0085] The fixing material 60 is made of, for example, an insulating material having heat resistance and flexibility. Examples of insulating materials that make up the fixing material 60 include epoxy resin, glass, ceramics, or composite materials of epoxy resin and ceramics. When ceramics or a composite material of epoxy resin and ceramics is used as the insulating material for the fixing material 60, the material of the ceramics may be the same as the material of the piezoelectric ceramic that makes up the piezoelectric body 11.

[0086] Here, as shown in Figures 12 and 13, in the other embodiment 5, the fixing material 60 fixes at least the protruding portion 44 of the electrode plate 40 to the laminate 10 while maintaining the first air gap G1 between the protruding portion 44 and the laminate 10. In other words, in the other embodiment 5, the piezoelectric element 1 has a first air gap G1 between the fixing material 60, the protruding portion 44, and the laminate 10.

[0087] As a result, the protrusions 44 on the first void G1 expand and contract along the lamination direction D in accordance with the expansion and contraction of the laminate 10, and the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 (near one end 43a) can be released to the interface between the fixing material 60 and the laminate 10. Therefore, according to the other embodiment 5, the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 (near one end 43a) due to the expansion and contraction of the laminate 10 in the lamination direction D can be dispersed, and the possibility of the electrode plate 40 peeling off from the conductor layer 20 can be reduced.

[0088] <Other Embodiments 6> Figures 14 and 15 are cross-sectional views showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 6. Figure 14 corresponds to the cross-sectional view taken along the line XII-XII in Figure 11, and Figure 15 corresponds to the cross-sectional view taken along the line XIII-XIII in Figure 11. For the sake of clarity, the coating layer 50 is not shown in Figures 14 and 15.

[0089] In the other embodiment 6 shown in Figures 14 and 15, the configuration of the fixing member 60 differs from that of the other embodiment 5 described above. Specifically, in the other embodiment 6, the fixing member 60 has an overhang 61. The overhang 61 is positioned to protrude inward from the periphery of the projection 44 and is in contact with the laminate 10. Here, "inward from the periphery of the projection 44" can also be rephrased as the direction approaching the central axis of the projection 44 (electrode plate 40). The overhang 61 is an example of a first overhang.

[0090] In another embodiment 6, by providing an overhang 61 on the fixing material 60, the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 (near one end 43a) can be efficiently relieved at the interface between the fixing material 60 and the laminate 10 as the laminate 10 expands and contracts in the lamination direction D. Therefore, according to another embodiment 6, the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 due to the expansion and contraction of the laminate 10 in the lamination direction D can be distributed more efficiently, and the possibility of the electrode plate 40 peeling off from the conductor layer 20 can be further reduced.

[0091] <Other Embodiments 7> Figure 16 is an enlarged plan view showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 7. Figure 17 is a cross-sectional view taken along the line XVII-XVII shown in Figure 16.

[0092] As shown in Figures 16 and 17, in another embodiment 7, the fixing member 60 fixes the main body portion 43 and the conductor layer 20 to the laminate 10 at one end of the conductor layer 20 located on the side of one end 43a of the main body portion 43.

[0093] As a result, in the other embodiment 7, the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 (near one end 43a) in response to the expansion and contraction of the laminate 10 in the lamination direction D can be efficiently relieved by the interface between the fixing material 60 and the laminate 10. Therefore, according to the other embodiment 7, the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 due to the expansion and contraction of the laminate 10 in the lamination direction D can be distributed more efficiently, and the possibility of the electrode plate 40 peeling off from the conductor layer 20 can be further reduced.

[0094] <Other Embodiments 8> Figure 18 is a cross-sectional view showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 8. Figure 18 corresponds to the cross-sectional view taken along the line XVII-XVII shown in Figure 16.

[0095] As described above, the main body 43 has a first portion 431 that is in contact with the bonding material 30, and a second portion 432 located on both sides of the first portion 431 in the width direction (i.e., the direction intersecting the lamination direction D), which faces the conductor layer 20 without being in contact with the bonding material 30. The second portion 432 faces the conductor layer 20 across the second void G2.

[0096] In another embodiment 8 shown in Figure 18, the configuration of the fixing member 60 differs from that of the other embodiment 7 described above. Specifically, in other embodiment 8, the fixing member 60 has a protruding portion 62. The protruding portion 62 is positioned to protrude inward from the side of the second portion 432 and is in contact with the conductor layer 20. Here, "inward from the side of the second portion 432" can also be rephrased as the direction approaching the central axis of the protruding portion 44 (electrode plate 40). The protruding portion 62 is an example of a second protruding portion.

[0097] In another embodiment 8, by providing an overhang 62 on the fixing material 60, the adhesion between the fixing material 60 and the conductor layer 20 is improved compared to the case where the overhang 62 is not provided, and therefore the adhesion between the fixing material 60 and the laminate 10 is improved. Accordingly, according to another embodiment 8, the possibility of the conductor layer 20 peeling off from the laminate 10 can be reduced.

[0098] <Other Embodiments 9> Figure 19 is an enlarged plan view showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 9. Figure 20 is a cross-sectional view taken along the line XX-XX shown in Figure 19.

[0099] As shown in Figure 19, in another embodiment 9, the covering layer 50 that covers the main body 43 and the conductor layer 20 is located on the side surface 10a of the laminate 10 (an example of a surface located along the lamination direction D of the laminate 10). Although not shown in Figure 19, the covering layer 50 that covers the main body 43 and the conductor layer 20 is also located on the side surface 10b of the laminate 10 (an example of a surface located along the lamination direction D of the laminate 10). By arranging such covering layers 50 on the side surfaces 10a and 10b, the main body 43 and the conductor layer 20 can be protected.

[0100] The coating layer 50 is composed of, for example, an insulator. Examples of insulators that make up this coating layer 50 include fluororesins, silicone resins, epoxy resins, and nylon resins.

[0101] In another embodiment 9, as shown in Figures 19 and 20, the end of the covering layer 50 covers the end of the fixing material 60 located on one end 43a side of the main body portion 43.

[0102] As a result, in the other embodiment 9, the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 (near one end 43a) in accordance with the expansion and contraction of the laminate 10 in the lamination direction D can be released to the interface between the fixing material 60 and the laminate 10 and the interface between the coating layer 50 and the laminate 10. Therefore, according to the other embodiment 9, the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 due to the expansion and contraction of the laminate 10 in the lamination direction D can be distributed more efficiently, and the possibility of the electrode plate 40 peeling off from the conductor layer 20 can be further reduced.

[0103] <Other Embodiments 10> Figure 21 is a cross-sectional view showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 10. Figure 21 is shown in Figure 19 X X -X X This corresponds to a cross-sectional view as seen through the arrows.

[0104] In the other embodiment 10 shown in Figure 21, the configuration of the coating layer 50 differs from that of the other embodiment 9 described above. Specifically, in the other embodiment 10, the coating layer 50 is located around the entire circumference of the side surface of the laminate 10, including side surface 10a. That is, the coating layer 50 is located not only on side surfaces 10a and 10b of the laminate 10, but also on side surfaces 10c (see Figure 1) and 10d (see Figure 1), which are located between side surfaces 10a and 10b.

[0105] As a result, in the other embodiment 10, the stress generated in the coating layer 50 in response to the expansion and contraction of the laminate 10 in the lamination direction D can be distributed to the entire circumference of the side surface of the laminate 10.

[0106] <Other Embodiments 11> Figure 22 is an enlarged plan view showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 11. As described above, the laminate 10 is composed of an active portion 10A formed by alternately stacking multiple piezoelectric bodies 11 and internal electrodes 12, and an inactive portion 10B arranged at both ends of the stacking direction D in the active portion, which has piezoelectric bodies 11 but does not have internal electrodes 12.

[0107] As shown in Figure 22, in another embodiment 11, the electrode plate 40 has a wider portion 45 that is wider than the other portions, at least at the protruding portion 44, at a position that overlaps with the inert portion 10B in a plan view. In another embodiment 11, the fixing material 60 may fix the wider portion 45 to the laminate 10.

[0108] As a result, in the other embodiment 11, the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 (near one end 43a) in accordance with the expansion and contraction of the laminate 10 in the lamination direction D can be efficiently relieved by the interface between the fixing material 60 and the laminate 10. Therefore, according to the other embodiment 11, the stress generated at the end of the joint between the electrode plate 40 and the conductor layer 20 due to the expansion and contraction of the laminate 10 in the lamination direction D can be distributed more efficiently, and the possibility of the electrode plate 40 peeling off from the conductor layer 20 can be further reduced.

[0109] <Other Embodiments 12> Figure 23 is a cross-sectional view showing an example of the configuration of the electrode plate 40 and its surroundings according to another embodiment 12. Figure 23 corresponds to the cross-sectional view taken along the line XXI-XXI shown in Figure 19.

[0110] In another embodiment 12 shown in Figure 23, the protrusion 44 is inclined such that the distance between the protrusion 44 and the laminate 10 narrows towards the tip 44a of the protrusion 44. In other words, the protrusion 44 is sloped downwards toward the tip 44a of the protrusion 44.

[0111] As a result, in the other embodiment 12, a portion of the uncured fixing material 60 is adequately filled into the gap between the tip 44a of the protrusion 44 and the laminate 10, thereby improving the adhesion strength between the tip 44a of the protrusion 44 and the laminate 10 after the fixing material 60 has cured.

[0112] <Other> Furthermore, in Figures 9 and 10, the shape of the through-hole H is rectangular in plan view, but it may be rounded near the edges in the width direction of the electrode plate 40. In this case, the risk of stress concentration at the corners and crack formation during expansion and contraction can be reduced.

[0113] <Manufacturing method for piezoelectric elements> Next, a method for manufacturing an example of the piezoelectric element 1 of this embodiment will be described. First, a ceramic green sheet, which will become the piezoelectric layer (piezoelectric 11), is prepared. Specifically, a ceramic slurry is prepared by mixing calcined piezoelectric ceramic powder, a binder having an organic polymer such as acrylic or butyral, and a plasticizer. Then, a ceramic green sheet is prepared from this ceramic slurry by using a tape molding method such as the well-known doctor blade method or calender roll method. As for the piezoelectric ceramic, any material having piezoelectric properties is acceptable, and for example, a perovskite-type oxide having PbZrO3-PbTiO3 can be used. As for the plasticizer, dibutyl phthalate (DBP) or dioctyl phthalate (DOP) can be used.

[0114] Next, a conductive paste to serve as the internal electrode 12 is prepared. Specifically, the conductive paste is prepared by adding and mixing a binder and a plasticizer to a silver-palladium alloy metal powder. This conductive paste is then printed onto the ceramic green sheet using a screen printing method. Next, multiple ceramic green sheets with the conductive paste printed on them are stacked, and multiple ceramic green sheets without the conductive paste printed on them are stacked on both ends in the stacking direction to obtain a laminated molded body. After debinding this laminated molded body at a predetermined temperature, the laminated body 10 is obtained by firing it at 900 to 1200°C.

[0115] Subsequently, a conductive paste made of silver and glass is applied to the side surface of the laminate 10 and baked to form a conductive layer 20. The conductive paste is made by adding and mixing a binder, plasticizer, glass powder, etc., to a metal powder mainly consisting of silver, and the conductive layer 20 can be formed by printing it on the side surface of the laminate 10 using a screen printing method or the like and baking it at 600 to 800°C.

[0116] Next, the bonding material 30 is applied to the upper surface of the conductor layer 20, and the electrode plate 40 is bonded to it. Then, the bonding material 30 is dried at a temperature of 100 to 140°C, and subsequently cured at a temperature of 180 to 220°C to fix the electrode plate 40 in place.

[0117] Subsequently, when the coating layer 50 is applied to the laminate 10 by a general coating method such as dipping, and after degassing treatment, the coating layer 50 is cured, minute voids of 0.1 μm or less may be dispersed within the coating layer 50, but voids G will not be formed. Therefore, voids G can also be formed by using a high-viscosity resin as the coating layer 50 and applying it to the predetermined position by screen printing. In addition, voids G can also be formed by the following method, for example.

[0118] A photosensitive coating layer 50 is applied to the laminate 10. Then, a gap G is created between the electrode plate 40 and the conductor layer 20, and light is irradiated to cure the coating layer 50 before it flows into the gap G. By this method, the piezoelectric element 1 of this example is manufactured.

[0119] Another method involves applying the coating layer 50 twice. Specifically, the coating layer 50 is applied before fixing the bonding material 30 and the electrode plate 40. Then, the conductive layer 20 is exposed by plasma etching or blasting at the location where the electrode plate 40 is to be fixed, the bonding material 30 and the electrode plate 40 are fixed, and the coating layer 50 is applied again on top of the electrode plate 40 to form the void G.

[0120] Furthermore, the electrode plate 40 having the protrusions 41(42) shown in Figures 7 and 8 is fixed to the laminate 10 to reduce the gap between the protrusions 41(42) and the conductor layer 20, and the coating layer 50 is applied by screen printing. This makes it difficult for the coating layer 50 to flow into the protrusions 41(42), and by hardening the coating layer 50 in this state, a void G is formed. The piezoelectric element 1 of this example is manufactured by the above method.

[0121] As described above, the piezoelectric element according to the embodiment (e.g., piezoelectric element 1) comprises a laminate (e.g., laminate 10), a conductor layer (e.g., conductor layer 20), an electrode plate (e.g., electrode plate 40), and a coating layer (e.g., coating layer 50). The laminate has multiple piezoelectric elements (e.g., piezoelectric element 11) and internal electrodes (e.g., internal electrodes 12) stacked on top of each other. The conductor layer is connected to the internal electrodes and is located along the stacking direction of the laminate (e.g., stacking direction D). The electrode plate is bonded to the conductor layer via a conductive bonding material (e.g., bonding material 30) and is located along the stacking direction of the laminate. The coating layer covers the conductor layer and the electrode plate. The electrode plate has a plurality of slits (e.g., slit S) extending in a direction intersecting the stacking direction (e.g., width direction). The piezoelectric element has a first void (e.g., void G) between the electrode plate, the conductor layer, and the bonding material. This reduces the possibility of peeling of the electrode plate covered with the coating layer.

[0122] Furthermore, the following additional information is disclosed regarding the above embodiments.

[0123] (Note 1) A laminate in which multiple piezoelectric materials and internal electrodes are stacked, A conductive layer connected to the internal electrode and positioned along the stacking direction of the laminate, An electrode plate is bonded to the conductor layer via a conductive bonding material and is positioned along the lamination direction of the laminate, The conductor layer and the covering layer covering the electrode plate, Equipped with, The electrode plate has a plurality of slits extending in a direction intersecting the stacking direction, A piezoelectric element having a first void between the electrode plate, the conductor layer, and the bonding material.

[0124] (Note 2) The piezoelectric element according to Appendix 1, wherein the coating layer is positioned to protrude inward from the end of the electrode plate in a direction intersecting the lamination direction and has a first protruding portion that contacts the conductor layer.

[0125] (Note 3) The piezoelectric element according to Appendix 1 or 2, wherein the electrode plate has a first protrusion that rises in the thickness direction of the electrode plate at the periphery of the end of the electrode plate in a direction intersecting the stacking direction.

[0126] (Note 4) The piezoelectric element described in Appendix 3, wherein the first protrusion extends along the stacking direction of the laminate.

[0127] (Note 5) The piezoelectric element according to any one of the appendices 1 to 4, wherein the coating layer is positioned to protrude inward from the inner wall surface of the slit in the electrode plate and has a second protruding portion that contacts the conductor layer.

[0128] (Note 6) The piezoelectric element according to any one of the appendices 1 to 5, wherein the electrode plate has a second protrusion on the periphery of the slit that rises in the thickness direction of the electrode plate.

[0129] (Note 7) The piezoelectric element described in Appendix 6, wherein the second protrusion extends along the longitudinal direction of the slit.

[0130] (Note 8) A piezoelectric element according to any one of the appendices 1 to 7, wherein the gap between one end of the electrode plate located outward in a plan view from the bonding material in the width direction and the conductor layer, and the gap between the other end of the electrode plate and the conductor layer are separated.

[0131] (Note 9) The piezoelectric element according to any one of the appendices 1 to 8, wherein the electrode plate has through holes located between adjacent slits.

[0132] Further effects and other embodiments can be readily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0133] 1. Piezoelectric element 10 Laminate 10a~10d Side view 10e Proximal end 10f tip 11 Piezoelectric material 12 Internal electrode 12a 1st electrode 12b 2nd electrode 13. Planned Fault Line 20, 20A, 20B Conductor Layers 30 Bonding material 40,40A,40B electrode plate 41,42 Convex part 50 Covering layer 51,52 Overhang D Stacking direction G void H through hole S-slit

Claims

1. A laminate in which multiple piezoelectric materials and internal electrodes are stacked, A conductive layer connected to the internal electrode and positioned along the stacking direction of the laminate, An electrode plate is bonded to the conductor layer via a conductive bonding material and is positioned along the lamination direction of the laminate, The conductor layer and the covering layer covering the electrode plate, Equipped with, The electrode plate has a plurality of slits extending in a direction intersecting the stacking direction, The electrode plate, the conductor layer, and the bonding material have a first void, A piezoelectric element wherein the coating layer is positioned to protrude inward from the edges of the electrode plates in a direction intersecting the lamination direction and has a first protruding portion that contacts the conductor layer.

2. A laminate in which multiple piezoelectric materials and internal electrodes are stacked, A conductive layer connected to the internal electrode and positioned along the stacking direction of the laminate, An electrode plate is bonded to the conductor layer via a conductive bonding material and is positioned along the lamination direction of the laminate, The conductor layer and the covering layer covering the electrode plate, Equipped with, The electrode plate has a plurality of slits extending in a direction intersecting the stacking direction, The electrode plate, the conductor layer, and the bonding material have a first void, The electrode plate has a first protrusion that rises in the thickness direction of the electrode plate at the periphery of the end of the electrode plate in a direction intersecting the stacking direction, The first protrusion is a piezoelectric element that extends along the stacking direction of the laminate.

3. A laminate in which multiple piezoelectric materials and internal electrodes are stacked, A conductive layer connected to the internal electrode and positioned along the stacking direction of the laminate, An electrode plate is bonded to the conductor layer via a conductive bonding material and is positioned along the lamination direction of the laminate, The conductor layer and the covering layer covering the electrode plate, Equipped with, The electrode plate has a plurality of slits extending in a direction intersecting the stacking direction, The electrode plate, the conductor layer, and the bonding material have a first void, A piezoelectric element wherein the coating layer is positioned to protrude inward from the inner wall surface of the slit in the electrode plate and has a second protruding portion that contacts the conductor layer.

4. A laminate in which multiple piezoelectric materials and internal electrodes are stacked, A conductive layer connected to the internal electrode and positioned along the stacking direction of the laminate, An electrode plate is bonded to the conductor layer via a conductive bonding material and is positioned along the lamination direction of the laminate, The conductor layer and the covering layer covering the electrode plate, Equipped with, The electrode plate has a plurality of slits extending in a direction intersecting the stacking direction, The electrode plate, the conductor layer, and the bonding material have a first void, A piezoelectric element in which the gap between one end of the electrode plate located outward in a plan view from the bonding material in the width direction and the conductor layer, and the gap between the other end of the electrode plate and the conductor layer are separated.

5. The piezoelectric element according to any one of claims 1 to 4, wherein the electrode plate has through holes located between adjacent slits.

6. The piezoelectric element according to any one of claims 1 to 4, wherein the electrode plate has a second protrusion on the periphery of the slit that rises in the thickness direction of the electrode plate.

7. The piezoelectric element according to claim 6, wherein the second protrusion extends along the longitudinal direction of the slit.

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