Piezoelectric element and drive device

Abstract

To provide a piezoelectric element and a drive device capable of suppressing variation in operation characteristics.SOLUTION: The element body 11 of the piezoelectric device 2 includes a drive region 12A in which the drive unit 15 is disposed, the drive unit 15 including the first internal electrodes 12B and the second internal electrodes D1 facing the first direction F1 with the piezoelectric layer 14 interposed therebetween. The driving unit 15 includes a plurality of first driving units D2 arranged in the third direction D3 on one side of the second direction 15A and a plurality of second driving units D2 arranged in the third direction D3 on the other side of the second direction 15B. When the body 11 is viewed from the D1 in the first direction, the first driving units 15A and the second driving units 15B are alternately arranged with respect to the D3 in the third direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to piezoelectric elements and drive devices. [Background technology]

[0002] A conventional piezoelectric element is one in which a plurality of drive units are arranged (see, for example, Patent Document 1). This conventional piezoelectric element is used as a power source for ejecting droplets of ink or the like in a printing device, and includes a pair of element bodies made up of a plurality of piezoelectric layers stacked in a first direction. The pair of element bodies are arranged on a base member with a predetermined gap between them.

[0003] Each element body has a predetermined width in a second direction perpendicular to the first direction, and extends in a third direction perpendicular to the first and second directions. Each element body has a driving section that generates distortion deformation by having a first internal electrode and a second internal electrode facing each other in the stacking direction with a piezoelectric layer sandwiched between them. In each element body, the driving section extends along the third direction, which is the extension direction of the element body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-98799 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional piezoelectric element described above, multiple drive units are arranged in close proximity, which can cause interference between the drive units, which can lead to variations in the operating characteristics of the piezoelectric element.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a piezoelectric element and a driving device that can suppress variations in operating characteristics. [Means for solving the problem]

[0007] The gist of the present disclosure is as follows.

[0008] [1] A piezoelectric element comprising: a body composed of a plurality of piezoelectric layers stacked in a first direction, having a predetermined width in a second direction perpendicular to the first direction, and extending in a third direction perpendicular to the first and second directions; the body including a driving region in which a driving unit is arranged, the driving unit being opposed in the first direction by first internal electrodes and second internal electrodes sandwiching the piezoelectric layers; a first external electrode electrically connected to the first internal electrode; and a second external electrode electrically connected to the second internal electrode; the driving unit having a plurality of first driving units arranged in the third direction on one side of the second direction and a plurality of second driving units arranged in the third direction on the other side of the second direction; when the body is viewed from the first direction, the first driving units and the second driving units are arranged alternately in the third direction.

[0009] In this piezoelectric element, multiple first drive units are arranged on one side of the element body in the second direction, and multiple second drive units are arranged on the other side of the element body in the second direction. Furthermore, when the element body is viewed from the first direction, the first drive units and second drive units are arranged alternately in the third direction. This configuration allows the drive units to be sufficiently spaced apart in the second and third directions, and even when multiple drive units are arranged in the drive region of the element body, drive interference between the drive units can be suppressed. By suppressing drive interference between the drive units, variation in the operating characteristics of the piezoelectric element can be suppressed.

[0010] [2] The piezoelectric element according to [1], wherein the first drive units and the second drive units are arranged in a staggered manner when the element body is viewed from the first direction. This arrangement allows the drive units to be more sufficiently spaced apart in the second and third directions. Therefore, interference between the drive units can be more effectively suppressed.

[0011] [3] The piezoelectric element according to [1] or [2], wherein the first driving unit and the second driving unit are spaced apart in the second direction when the element body is viewed from the third direction. This arrangement allows the driving units to be more sufficiently spaced apart in the second direction. Therefore, interference between the driving units can be more effectively suppressed.

[0012] [4] The piezoelectric element according to any one of [1] to [3], wherein a non-driving region in which neither the first driving section nor the second driving section is arranged is provided at an end of the element body in the third direction, and a dummy electrode formed by the first internal electrode or the second internal electrode is arranged in the non-driving region. In this case, the thickness of the element body in the first direction in the driving region can be made the same as the thickness of the element body in the first direction in the non-driving region.

[0013] [5] A driving device comprising the piezoelectric element according to any one of [1] to [4] and a wiring section electrically connected to the first external electrode and the second external electrode. By using the piezoelectric element described above, this driving device can extract an output to the outside while suppressing variations in operating characteristics.

[0014] [6] The element body has a plurality of first recesses with bottoms extending in the second direction, and the first drive units and the second drive units arranged alternately in the third direction are separated by the first recesses. In this case, the first recesses physically separate the first drive units and the second drive units in the third direction. Therefore, interference between the drive units can be more effectively suppressed. Furthermore, because the first recesses have bottoms, displacement of the element body can be restricted at the bottom of the first recesses.

[0015] [7] The drive device according to [6], wherein the element body portion separated by the first recess is continuous in the second direction. By providing the element body portion continuous in the second direction, it is possible to suitably avoid interlocking of the drive of the first drive unit and the drive of the second drive unit.

[0016] [8] The drive device according to [6], wherein the element body portion separated by the first recess is separated into a first element body portion where the first drive unit is located and a second element body portion where the second drive unit is located by a second recess with a bottom extending in the third direction. In this case, the first recess and the second recess can physically separate the first drive unit and the second drive unit in both the second direction and the third direction. Therefore, interference between the drives of the drive units can be more effectively suppressed. Furthermore, because the second recess has a bottom, displacement of the element body can be restricted at the bottom of the second recess.

[0017] [9] The driving device according to [8], wherein the first external electrode electrically connected to the first internal electrode of the first driving unit is located on one end surface of the element body in the second direction, the first external electrode electrically connected to the first internal electrode of the second driving unit is located on the other end surface of the element body in the second direction, and the second external electrode electrically connected to the second internal electrode of the first driving unit and the second internal electrode of the second driving unit is located on an inner wall surface of the second recess and on an end surface of the element body in the third direction that is continuous with the inner wall surface. With this configuration, even when the first driving unit and the second driving unit are physically separated in both the second direction and the third direction by the first recess and the second recess, wiring units can be connected to the first external electrode and the second external electrode with a simple configuration.

[0018]

[10] The driving device according to any one of [5] to [9], further comprising a base substrate electrically connected to the second external electrode. In this case, the strength of the piezoelectric element can be ensured by the base substrate. Furthermore, by electrically connecting the base substrate to the piezoelectric element via the second external electrode, the base substrate can be used as the ground potential of the piezoelectric element. This stabilizes the driving of the piezoelectric element. [Effects of the Invention]

[0019] According to the present disclosure, variations in operating characteristics can be suppressed. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a perspective view of a drive device according to a first embodiment of the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 2(a) is a plan view showing an example of a pattern of a first internal electrode, and FIG. 2(b) is a plan view showing an example of a pattern of a second internal electrode. [Figure 6] FIG. 10(a) is a plan view showing another example of the pattern of the first internal electrode, and FIG. 10(b) is a plan view showing another example of the pattern of the second internal electrode. [Figure 7] FIG. 10 is a perspective view of a drive device according to a second embodiment of the present disclosure. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] 8 is a cross-sectional view taken along line XX in FIG. 7. [Figure 11] FIG. 2(a) is a plan view showing an example of a pattern of a first internal electrode, and FIG. 2(b) is a plan view showing an example of a pattern of a second internal electrode. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, preferred embodiments of a piezoelectric element and a driving device according to one aspect of the present disclosure will be described in detail with reference to the drawings.

[0022] [First embodiment] Fig. 1 is a perspective view of a driving device according to a first embodiment of the present disclosure. The driving device 1 shown in Fig. 1 is a device used as a power source for ejecting droplets of ink or the like in a printing machine, for example. As shown in Fig. 1, the driving device 1 is configured to include a piezoelectric element 2, a base substrate 3, and a wiring section 4 (see Fig. 2, etc.).

[0023] The piezoelectric element 2 includes a substantially rectangular parallelepiped body 11, multiple internal electrodes (first internal electrode 12A and second internal electrode 12B), and multiple external electrodes (first external electrode 13A, second external electrode 13B, third external electrode 13C, and fourth external electrode 13D). The body 11 is configured into a flat, substantially rectangular parallelepiped shape by multiple piezoelectric layers 14 (see FIG. 2, etc.) stacked in a first direction D1. The body 11 has a predetermined width in a second direction D2 perpendicular to the first direction D1, and extends in a third direction D3 perpendicular to the first direction D1 and the second direction D2.

[0024] In this embodiment, the element body 11 is made of a piezoelectric ceramic material. Examples of the piezoelectric ceramic material include lead zirconate titanate (PZT: Pb(Zr x ,Ti 1-x )O3) as a main component. Each piezoelectric layer 14 is formed, for example, from a sintered ceramic green sheet containing the piezoelectric ceramic material described above. In the element body 11, the piezoelectric layers 14 are integrated to the extent that their boundaries are indistinguishable.

[0025] The first internal electrode 12A and the second internal electrode 12B are formed of a conductive material containing, for example, silver and palladium as main components. The conductive material may be copper. The first internal electrode 12A and the second internal electrode 12B are, for example, a sintered body of a conductive paste containing a conductive material. The first external electrode 13A, the second external electrode 13B, and the third external electrode 13C are formed of a plurality of metal films made of, for example, chromium, copper / nickel, and gold. Instead of a gold metal film, a silver metal film, a silver-palladium alloy metal film, a silver-tin alloy metal film, or the like may be used.

[0026] The element body 11 has a driving region F1 that drives when a voltage is applied to the piezoelectric element 2, and a non-driving region F2 that does not drive when a voltage is applied to the piezoelectric element 2. In this embodiment, as shown in Fig. 1, both ends of the element body 11 in the third direction D3 are non-driving regions F2, and the driving region F1 is arranged so as to be sandwiched between the non-driving regions F2.

[0027] The driving region F1 is a region where driving units 15 (first driving unit 15A and second driving unit 15B) are arranged, in which the first internal electrode 12A and the second internal electrode 12B face each other in the first direction across the piezoelectric layer 14. In this embodiment, in the driving region F1, element body portions 11A provided with the first driving unit 15A and element body portions 11B provided with the second driving unit 15B are arranged alternately in the third direction D3.

[0028] The element body portion 11A and the element body portion 11B are separated by a bottomed first recess 16A extending in the second direction D2. In this embodiment, the depth direction of the first recess 16A is the direction from the end face 11a of the element body 11 opposite the base substrate 3 in the first direction D1 to the end face 11b on the base substrate 3 side in the first direction D1. The cross-sectional shape of the first recess 16A as viewed from the second direction D2 is, for example, rectangular. The first recess 16A separates the first internal electrode 12A and the second internal electrode 12B included in the element body portion 11A from the first internal electrode 12A and the second internal electrode 12B included in the element body portion 11B in the third direction D3. The element body portion 11A and the element body portion 11B separated by the first recess 16A are continuous in the second direction D2.

[0029] In this embodiment, the first recess 16A is also formed between one non-driving region F2 in the third direction D3 and the element body portion 11A, and between the other non-driving region F2 in the third direction D3 and the element body portion 11B. The first recess 16A divides, in the third direction D3, an internal electrode (here, the second internal electrode 12B) included in one non-driving region F2 in the third direction D3 and the first internal electrode 12A and the second internal electrode 12B included in the element body portion 11A. The first recess 16A also divides, in the third direction D3, an internal electrode (here, the second internal electrode 12B) included in the other non-driving region F2 in the third direction D3 and the first internal electrode 12A and the second internal electrode 12B included in the element body portion 11B.

[0030] 2, the element body portion 11A includes only a first driving section 15A. In the first driving section 15A, a first internal electrode 12A extending from one end face 11c of the element body 11 toward the other end face 11d in the second direction D2, and a second internal electrode 12B extending from the other end face 11d of the element body 11 in the second direction D2 toward the one end face 11c, face each other in the first direction D1 with the piezoelectric layer 14 sandwiched between them on one side in the second direction D2 (closer to the one end face 11c than the center of the element body 11 in the second direction D2).

[0031] 3, the element body portion 11B includes only the second drive unit 15B. In the second drive unit 15B, a first internal electrode 12A extending from one end face 11c of the element body 11 toward the other end face 11d in the second direction D2, and a second internal electrode 12B extending from the other end face 11d of the element body 11 in the second direction D2 toward the one end face 11c, face each other in the first direction D1 with the piezoelectric layer 14 sandwiched between them on the other side of the second direction D2 (closer to the other end face 11d than the center of the element body 11 in the second direction D2).

[0032] With the above-described configuration, in drive region F1, multiple first drive units 15A are arranged in the third direction D3 on one side of second direction D2, and multiple second drive units 15B are arranged in the third direction D3 on the other side of second direction D2. Since element body parts 11A on which first drive units 15A are provided and element body parts 11B on which second drive units 15B are provided are arranged alternately in the third direction D3, when element body 11 is viewed from first direction D1, first drive units 15A and second drive units 15B are arranged alternately in the third direction D3.

[0033] In this embodiment, the first driving unit 15A and the second driving unit 15B are arranged in a staggered manner when the element body 11 is viewed from the first direction D1. The first driving unit 15A and the second driving unit 15B are located on one end face 11c side and the other end face 11d side, respectively, with the center of the element body 11 in the second direction in between, and are spaced apart in the second direction D2 when the element body 11 is viewed from the third direction D3.

[0034] The non-driving region F2 is a region where no driving section 15 (first driving section 15A and second driving section 15B) is arranged, where the first internal electrode 12A and the second internal electrode 12B face each other in the first direction across the piezoelectric layer 14. In this embodiment, the non-driving region F2 is formed by the element body portion 11C that does not have either the first driving section 15A or the second driving section 15B.

[0035] In the element body portion 11C, a dummy electrode 17 made of the first internal electrode 12A or the second internal electrode 12B is arranged, as shown in Fig. 4. In the example of Fig. 4, a dummy electrode 17 made of the second internal electrode 12B is arranged. The second internal electrode 12B constituting the dummy electrode 17 in the element body portion 11C is at the same position in the first direction D1 as the second internal electrodes 12B of the element body portions 11A and 11B, and extends so as to connect one end face 11c and the other end face 11d of the element body 11 in the second direction D2.

[0036] Fig. 5(a) is a plan view showing an example of the pattern of the first internal electrode, and Fig. 5(b) is a plan view showing an example of the pattern of the second internal electrode. As shown in Fig. 5(a), the pattern P1 of the first internal electrode 12A has electrode portions d1a extending from one end face 11c of the element body 11 in the second direction D2 to just before the center, and electrode portions d1b extending from the one end face 11c of the element body 11 in the second direction D2 beyond the center toward the other end face 11d. The electrode portions d1a and the electrode portions d1b are arranged alternately in the third direction.

[0037] As shown in FIG. 5(b), the pattern P2 of the second internal electrode 12B has electrode portions d2a extending from the other end face 11d in the second direction D2 of the element body 11 to just before the center, and electrode portions d2b extending from the other end face 11d in the second direction D2 of the element body 11 past the center toward the one end face 11c. The electrode portions d2a and d2b are alternately arranged in the third direction D3. The arrangement order of the electrode portions d2a and d2b in the third direction D3 is reversed from the arrangement order of the electrode portions d1a and d1b in the third direction D3. Electrode portions d2c connecting the one end face 11c and the other end face 11d in the second direction D2 of the element body 11 are arranged at both ends in the third direction D3.

[0038] The element body 11 is formed by alternately stacking the patterns P1 of the first internal electrode 12A and the patterns P2 of the second internal electrode 12B in the first direction D1 with the piezoelectric layers 14 interposed therebetween, whereby in the driving region F1, a first driving section 15A is formed by electrode portions d1a and d2b opposing each other with the piezoelectric layers interposed therebetween, and a second driving section 15B is formed by electrode portions d1b and d2a opposing each other with the piezoelectric layers 14 interposed therebetween. In the non-driving region F2, a dummy electrode 17 is formed by electrode portions d2c.

[0039] A first recess 16A with a bottom extending in the second direction D2 along the processing line K1 is formed in the formed element body 11. This divides the element body 11 into an element body portion 11A having the first driving unit 15A, an element body portion 11B having the second driving unit 15B, and an element body portion 11C having the dummy electrode 17, and the driving region F1 and non-driving region F2 described above are formed in the element body 11.

[0040] 1, the multiple external electrodes are composed of a first external electrode 13A electrically connected to the first internal electrode 12A, a second external electrode 13B electrically connected to the second internal electrode 12B, and a third external electrode 13C and a fourth external electrode 13D connected to the dummy electrode 17. The first external electrode 13A is, for example, a positive electrode. As shown in FIGS. 2 and 3, the first external electrode 13A is arranged over the entire one end surface 11c of the element body 11 in the second direction D2 in the element body portions 11A and 11B belonging to the driving region F1, and is electrically connected to the first internal electrode 12A at this one end surface 11c.

[0041] 2 and 3, the second external electrode 13B is disposed in the driving region F1, spaced apart from the first external electrode 13A, over the entire end face 11b of the element body 11 facing the base substrate 3 in the first direction D1. In the element body portions 11A and 11B, the second external electrode 13B is disposed over the entire other end face 11d of the element body 11 in the second direction D2, and is electrically connected to the second internal electrode 12B at the other end face 11d.

[0042] As shown in Fig. 4, the third external electrode 13C is arranged over the entire surface of one end surface 11c of the element body 11 in the second direction D2 in the element body portion 11C belonging to the non-driving region F2, and is electrically connected to the second internal electrode 12B at this end surface 11c. As shown in Fig. 4, the fourth external electrode 13D is arranged over the entire surface of the end surface 11b of the element body 11 facing the base substrate 3 in the first direction D1, while being spaced apart from the third external electrode 13C, in the non-driving region F2. The fourth external electrode 13D is continuous with the second external electrode 13B at this end surface 11b. Furthermore, the fourth external electrode 13D is arranged over the entire surface of the other end surface 11d of the element body 11 in the second direction D2 in the element body portion 11C, and is electrically connected to the second internal electrode 12B at this other end surface 11d.

[0043] The base substrate 3 is a member that holds the piezoelectric elements 2. The base substrate 3 is made of, for example, a metal and has a flat, approximately rectangular parallelepiped shape that corresponds to the shape of the piezoelectric elements 2. Examples of metal materials that form the base substrate 3 include metals such as SUS. The base substrate 3 is electrically connected to the second external electrode 13B. In this embodiment, the base substrate 3 is provided with electrode pads (not shown). The base substrate 3 is electrically connected to the second external electrode 13B and the fourth external electrode 13D via the electrode pads.

[0044] The wiring section 4 is configured by, for example, a flexible printed circuit board 18. In this embodiment, as shown in Figures 2 to 4, the flexible printed circuit board 18 is arranged only on one end surface 11c of the element body 11 in the second direction D2. The flexible printed circuit board 18 is electrically connected to each of the first external electrode 13A and the third external electrode 13C located on one end surface 11c of the element body 11 in the second direction D2.

[0045] In the driving device 1, the driving unit 15 belonging to the driving region F1 can be distorted and deformed by applying voltages of opposite polarities to the first external electrode 13A and the second external electrode 13B via the base substrate 3 and the flexible printed circuit board 18. By applying different potential differences to the first driving unit 15A and the second driving unit 15B via the base substrate 3 and the flexible printed circuit board 18, the first driving unit 15A and the second driving unit 15B can be driven independently.

[0046] As described above, in the piezoelectric element 2, multiple first driving units 15A are arranged on one side of the element body 11 in the second direction D2, and multiple second driving units 15B are arranged on the other side of the element body 11 in the second direction D2. Furthermore, when the element body 11 is viewed from the first direction D1, the first driving units 15A and the second driving units 15B are arranged alternately in the third direction D3. This configuration allows the driving units 15 to be sufficiently spaced apart in the second direction D2 and the third direction D3, and suppresses interference between the driving units 15 even when multiple driving units 15 are arranged in the driving region F1 of the element body 11. By suppressing interference between the driving units 15, variations in the operating characteristics of the piezoelectric element 2 can be suppressed.

[0047] In this embodiment, when the element body 11 is viewed from the first direction D1, the first driving unit 15A and the second driving unit 15B are arranged in a staggered pattern. Furthermore, when the element body 11 is viewed from the third direction D3, the first driving unit 15A and the second driving unit 15B are spaced apart in the second direction D2. This arrangement allows the driving units 15 to be spaced apart more sufficiently in the second direction D2 and the third direction D3. Therefore, interference between the driving operations of the driving units 15 can be more effectively suppressed.

[0048] In this embodiment, a non-driving region F2 in which neither the first driving unit 15A nor the second driving unit 15B is arranged is provided at the end of the element body 11 in the third direction D3, and a dummy electrode 17 formed by the first internal electrode 12A or the second internal electrode 12B (the second internal electrode 12B in this embodiment) is arranged in the non-driving region F2. In this case, the thickness of the element body 11 in the first direction D1 in the driving region F1 can be made uniform to the thickness of the element body 11 in the first direction D1 in the non-driving region F2. By making the thickness of the element body 11 in the first direction D1 uniform between the driving region F1 and the non-driving region F2, it is possible to prevent unnecessary stress from being applied to the element body 11 when, for example, the piezoelectric element 2 is driven.

[0049] The driving device 1 also includes the above-described piezoelectric element 2 and a wiring section 4 electrically connected to the first external electrode 13A and the second external electrode 13B. By using the above-described piezoelectric element 2, the driving device 1 can extract an output to the outside while suppressing variations in operating characteristics.

[0050] In this embodiment, the element body 11 has multiple first recesses 16A with a bottom that extend in the second direction D2. The first driving units 15A and second driving units 15B, which are arranged alternately in the third direction D3, are separated by the first recesses 16A. By providing such first recesses 16A in the element body 11, the first driving units 15A and second driving units 15B can be physically separated in the third direction D3. Therefore, interference between the driving units 15 can be more effectively suppressed. Furthermore, because the first recesses 16A have a bottom, the displacement of the element body 11 can be restrained at the bottom of the first recesses 16A.

[0051] In this embodiment, element body portion 11A and element body portion 11B, which are separated by first recess 16A, are continuous in second direction D2 in element body 11. By providing element body portions that are continuous in second direction D2, it is possible to suitably avoid interlocking between the driving of first driving unit 15A and the driving of second driving unit 15B.

[0052] In this embodiment, the driving device 1 includes a base substrate 3 electrically connected to the second external electrode 13B. In this case, the strength of the piezoelectric element 2 can be ensured by the base substrate 3. Furthermore, by electrically connecting the base substrate 3 to the piezoelectric element 2 via the second external electrode 13B, the base substrate 3 can be used as the ground potential of the piezoelectric element 2. This stabilizes the driving of the piezoelectric element 2.

[0053] Fig. 6(a) is a plan view showing another example of the pattern of the first internal electrode, and Fig. 6(b) is a plan view showing another example of the pattern of the second internal electrode. As shown in Fig. 6(a), the pattern P3 of the first internal electrode 12A differs from the pattern P1 of the first internal electrode 12A shown in Fig. 5(a) in that, in the electrode portions d1b adjacent to each other in the second direction D2, the tips of the electrode portions d1b that are closer to the other end face 11d than the center in the second direction D2 are connected by the electrode portion d3a. Furthermore, in the electrode portions d1b, the width of the center portion in the second direction D2 is smaller than the width of the other portions.

[0054] 6(b), the pattern P4 of the second internal electrode 12B differs from the pattern P2 of the second internal electrode 12B shown in FIG. 5(b) in that, in the electrode portions d2b adjacent to each other in the second direction, the tips of the electrode portions d2b that are closer to the one end face 11c than the center in the second direction D2 are connected by the electrode portion d4a. Furthermore, in the electrode portions d1b, the width of the center portion in the second direction D2 is smaller than the width of the other portions.

[0055] Even when the element body 11 is formed by alternately stacking the patterns P3 of the first internal electrodes 12A and the patterns P4 of the second internal electrodes 12B in the first direction D1 with the piezoelectric layers 14 interposed therebetween, the first driving section 15A is formed in the driving region F1 by the electrode portions d1a and d2b opposing each other with the piezoelectric layers interposed therebetween, and the second driving section 15B is formed in the driving region F1 by the electrode portions d1b and d2a opposing each other with the piezoelectric layers interposed therebetween. In the non-driving region F2, a dummy electrode 17 is formed by the electrode portions d2c.

[0056] When the pattern P3 of the first internal electrode 12A and the pattern P4 of the second internal electrode 12B are used, an opposing portion is formed on the other end face 11d in the second direction D2 of the element portion 11A, where the base end portion of the electrode portion d2b and the electrode portion 3a face each other via the piezoelectric layer 14, and an opposing portion is formed on one end face 11c in the second direction D2 of the element portion 11B, where the base end portion of the electrode portion d1b and the electrode portion d4a face each other via the piezoelectric layer 14. By providing the first recess 16A in the element body 11, these opposing portions become dummy driving units that are physically separated from the first driving unit 15A, the second driving unit 15B, the first external electrode 13A, and the second external electrode 13B.

[0057] By arranging such dummy driving parts, the thickness in the first direction D1 on the one end face 11c side in the second direction D2 and the thickness in the first direction D1 on the other end face 11d side in the second direction D2 can be made uniform in element body parts 11A and 11B. By making these thicknesses uniform, it is possible to prevent unnecessary stress from being applied to element body 11 when, for example, piezoelectric element 2 is driven.

[0058] [Second embodiment] Fig. 7 is a perspective view of a drive device according to a second embodiment of the present disclosure. As shown in Fig. 7, a drive device 21 according to the second embodiment differs from the first embodiment in that, in a piezoelectric element 2, body portions 11A and 11B separated by a first recess 16A are further separated by a second recess 16B with a bottom that extends in a third direction D3. Accordingly, the configurations of a first external electrode 13A, a second external electrode 13B, a third external electrode 13C, a fourth external electrode 13D, and a wiring portion 4 differ from those of the first embodiment.

[0059] In this embodiment, the depth direction of the second recess 16B is the direction from the end face 11b of the element body 11 facing the base substrate 3 in the first direction D1 to the end face 11a on the opposite side of the element body 11 from the base substrate 3 in the first direction D1. The cross-sectional shape of the second recess 16B as viewed in the third direction D3 is, for example, rectangular. The second recess 16B divides the element body 11 in the width direction at the center in the second direction D2. As a result, each of the element body portions 11A, 11B, and 11C separated by the first recess 16A is separated into a first element body portion 11M on the side of one end face 11c where the first driving unit 15A is located and a second element body portion 11N on the side of the other end face 11d where the second driving unit 15B is located.

[0060] 8, the element body portion 11A includes only the first driving unit 15A in the first element body portion 11M. In the first driving unit 15A, a first internal electrode 12A extending from one end face 11c of the element body 11 in the second direction D2 toward a first inner wall face (inner wall face on the one end face 11c side) 16a of the second recess 16B and a second internal electrode 12B extending from the first inner wall face 16a of the second recess 16B toward the one end face 11c of the element body 11 in the second direction D2 face each other in the first direction D1 with the piezoelectric layer 14 sandwiched between them.

[0061] 9, the element body portion 11B includes only the second driving section 15B in the second element body portion 11N. In the second driving section 15B, the first internal electrode 12A extending from the other end face 11d of the element body 11 in the second direction D2 toward the second inner wall surface (the inner wall surface on the other end face 11d side) 16b of the second recess 16B and the second internal electrode 12B extending from the second inner wall surface 16b of the second recess 16B toward the other end face 11d of the element body 11 in the second direction D2 face each other in the first direction D1 with the piezoelectric layer 14 sandwiched between them, on the other end face 11d side of the second recess 16B.

[0062] In the element body portion 11C, as shown in Fig. 10, dummy electrodes 17 made of the first internal electrode 12A or the second internal electrode 12B are arranged in both the first element body portion 11M and the second element body portion 11N. In the example of Fig. 10, a dummy electrode 17 made of the second internal electrode 12B is arranged. The second internal electrode 12B constituting the dummy electrode 17 in the first element body portion M is at the same position in the first direction D1 as the second internal electrodes 12B of the element body portions 11A and 11B, and extends so as to connect one end face 11c in the second direction D2 of the element body 11 and the first inner wall surface 16a of the second recess 16B. The second internal electrode 12B constituting the dummy electrode 17 in the second element body portion N is at the same position in the first direction D1 as the second internal electrodes 12B of the element body portions 11A, 11B, and extends so as to connect the other end face 11d in the second direction D2 of the element body 11 and the second inner wall surface 16b of the second recess 16B.

[0063] 11(a) is a plan view showing an example of the pattern of the first internal electrode, and FIG. 11(b) is a plan view showing an example of the pattern of the second internal electrode. As shown in FIG. 11(a), the pattern P5 of the first internal electrode 12A has an electrode portion d5a extending from one end face 11c of the element body 11 in the second direction D2 to just before the center, and an electrode portion d5b extending from the other end face 11d of the element body 11 in the second direction D2 to just before the center. The electrode portions d5a and d5b are arranged alternately in the third direction. The base ends of the electrode portions d5a are connected to each other by an electrode portion d5c extending in the third direction D3 along the one end face 11c, and the base ends of the electrode portions d5b are connected to each other by an electrode portion d5d extending in the third direction D3 along the other end face 11d.

[0064] 11(b), the pattern P6 of the second internal electrode 12B has an electrode portion d6a extending from the center of the element body 11 in the second direction D2 to just before one end face 11c, and an electrode portion d6b extending from the center of the element body 11 in the second direction D2 to just before the other end face 11d. The electrode portions d6a and d6b are arranged alternately in the third direction. The base ends of the electrode portions d6a, d6a are connected to each other by an electrode portion d6c extending in the third direction D3 at the center of the element body 11 in the second direction D2. Electrode portions d6d connecting the one end face 11c and the other end face 11d in the second direction D2 of the element body 11 are arranged at both ends in the third direction D3.

[0065] The element body 11 is formed by alternately stacking the patterns P5 of the first internal electrode 12A and the patterns P6 of the second internal electrode 12B in the first direction D1 with the piezoelectric layers 14 interposed therebetween, whereby in the driving region F1, a first driving section 15A is formed by electrode portions d5a and d6a facing each other with the piezoelectric layers interposed therebetween, and a second driving section 15B is formed by electrode portions d5b and d6b facing each other with the piezoelectric layers 14 interposed therebetween. In the non-driving region F2, a dummy electrode 17 is formed by electrode portion d6d.

[0066] A first recess 16A with a bottom extending in the second direction D2 along the processing line K1 is formed in the formed element body 11. This divides the element body 11 into an element body portion 11A having the first driving unit 15A, an element body portion 11B having the second driving unit 15B, and an element body portion 11C having the dummy electrode 17. In addition, a second recess 16B with a bolt extending in the third direction D3 along the processing line K2 is formed in the formed element body 11. This divides the element body 11 into a first element body portion 11M where the first driving unit 15A is located and a second element body portion 11N where the second driving unit 15B is located, and the above-mentioned driving region F1 and non-driving region F2 are formed in the element body 11.

[0067] 8 and 9, in this embodiment, the first external electrodes 13A are arranged on one end surface 11c and the other end surface 11d in the second direction D2 of the element body 11. Specifically, the first external electrode 13A electrically connected to the first internal electrode 12A of the first driving unit 15A is located on one end surface 11c in the second direction D2 of the element body 11, and the first external electrode 13A electrically connected to the first internal electrode 12A of the second driving unit 15B is located on the other end surface 11d in the second direction D2 of the element body 11.

[0068] On the other hand, the second external electrode 13B serves as a common electrode for the first driving unit 15A and the second driving unit 15B. As shown in Figures 8 and 9, the second external electrode 13B is arranged in the driving region F1, apart from the first external electrode 13A, over the entire end face 11b of the element body 11 facing the base substrate 3 in the first direction D1, and over the entire inner wall surfaces (first inner wall surface 16a, second inner wall surface 16b, and bottom surface 16c) of the second recess 16B.

[0069] 10, the third external electrode 13C is arranged over the entire surface of one end face 11c and the other end face 11d of the element body 11 in the second direction D2 in the element body portion 11C belonging to the non-driving region F2. The third external electrode 13C on the one end face 11c side is electrically connected at the one end face 11c to the second internal electrode 12B that constitutes the dummy electrode 17 that belongs to the first element body portion 11M. The third external electrode 13C on the other end face 11d side is electrically connected at the other end face 11d to the second internal electrode 12B that constitutes the dummy electrode 17 that belongs to the second element body portion 11N.

[0070] 10 , the fourth external electrode 13D is arranged in the non-driving region F2, separated from the third external electrode 13C, over the entire end face 11b of the element body 11 facing the base substrate 3 in the first direction D1 and over the entire inner wall surfaces (first inner wall surface 16a, second inner wall surface 16b, and bottom surface 16c) of the second recess 16B. The fourth external electrode 13D is continuous with the second external electrode 13B at the end face 11b and the inner wall surfaces of the second recess 16B. The fourth external electrode 13D is electrically connected at the first inner wall surface 16a to the second internal electrode 12B constituting the dummy electrode 17 belonging to the first element body portion 11M, and is electrically connected at the second inner wall surface 16b to the second internal electrode 12B constituting the dummy electrode 17 belonging to the second element body portion 11N.

[0071] In this embodiment, the flexible printed circuit boards 18 constituting the wiring section 4 are disposed on one end face 11c side and the other end face 11d side of the element body 11 in the second direction D2. The flexible printed circuit board 18 on the one end face 11c side is electrically connected to the first external electrode 13A and the third external electrode 13C on the one end face 11c side. The flexible printed circuit board 18 on the other end face 11d side is electrically connected to the first external electrode 13A and the third external electrode 13C on the other end face 11d side. The second external electrode 13B, which is a common electrode for the first drive unit 15A and the second drive unit 15B, is electrically connected to the base substrate 3 on the end face 11b side.

[0072] In the piezoelectric element 2 described above, similarly to the first embodiment, the driving units 15 can be sufficiently spaced apart in the second direction D2 and the third direction D3, and interference between the driving units 15 can be suppressed even when multiple driving units 15 are arranged in the driving region F1 of the element body 11. By suppressing interference between the driving units 15, variations in the operating characteristics of the piezoelectric element 2 can be suppressed.

[0073] In this embodiment, in the element body 11, element body portions 11A and 11B separated by the first recess 16A are separated by a bottomed second recess 16B extending in the third direction D3 into a first element body portion 11M where the first driving unit 15A is located and a second element body portion 11N where the second driving unit 15B is located. With this configuration, the first recess 16A and the second recess 16B can physically separate the first driving unit 15A and the second driving unit 15B in both the second direction D2 and the third direction D3. This can more effectively suppress interference between the driving units 15. Furthermore, because the second recess 16B has a bottom, displacement of the element body 11 can be restricted at the bottom of the second recess 16B.

[0074] In this embodiment, the first external electrode 13A electrically connected to the first internal electrode 12A of the first driving unit 15A is located on one end surface 11c in the second direction D2 of the element body 11, and the first external electrode 13A electrically connected to the first internal electrode 12A of the second driving unit 15B is located on the other end surface 11d in the second direction D2 of the element body 11. In addition, the second external electrode 13B electrically connected to the second internal electrode 12B of the first driving unit 15A and the second internal electrode 12B of the second driving unit 15B is located on the inner wall surface of the second recess 16B and on the end surface 11b in the third direction D3 of the element body 11 that is continuous with the inner wall surface. With this configuration, even if the first drive unit 15A and the second drive unit 15B are physically separated in both the second direction D2 and the third direction D3 by the first recess 16A and the second recess 16B, the wiring unit 4 can be connected to the first external electrode 13A and the second external electrode 13B with a simple configuration. [Explanation of symbols]

[0075] 1,21...drive device, 2...piezoelectric element, 3...base substrate, 11b...end surface, 11c...one end surface, 11d...other end surface, 4...wiring portion, 11...element body, 11A to 12C...element body portion, 11M...first element body portion, 11N...second element body portion, 12A...first internal electrode, 12B...second internal electrode, 12A...first external electrode, 12B...second external electrode, 14...piezoelectric layer, 15...drive portion, 15A...first drive portion, 15B...second drive portion, 16A...first recess, 16B...second recess, 16a, 16b...inner wall surface, 17...dummy electrode, D1...first direction, D2...second direction, D3...third direction, F1...drive region, F2...non-drive region.

Claims

1. an element body that is configured by a plurality of piezoelectric layers stacked in a first direction, has a predetermined width in a second direction perpendicular to the first direction, and extends in a third direction perpendicular to the first direction and the second direction; the element body includes a driving region in which a driving section is disposed, in which a first internal electrode and a second internal electrode face each other in the first direction with the piezoelectric layer sandwiched therebetween, and the element body also has a first external electrode electrically connected to the first internal electrode and a second external electrode electrically connected to the second internal electrode, the drive unit includes a plurality of first drive units arranged in the third direction on one side of the second direction, and a plurality of second drive units arranged in the third direction on the other side of the second direction, A piezoelectric element in which, when the element body is viewed from the first direction, the first driving sections and the second driving sections are arranged alternately in the third direction.

2. The piezoelectric element according to claim 1 , wherein the first driving portions and the second driving portions are arranged in a staggered manner when the element body is viewed from the first direction.

3. The piezoelectric element according to claim 1 , wherein the first driving section and the second driving section are spaced apart in the second direction when the element body is viewed from the third direction.

4. a non-driving region in which neither the first driving unit nor the second driving unit is disposed is provided at an end of the element body in the third direction, The piezoelectric element according to claim 1 , wherein a dummy electrode formed by the first internal electrode or the second internal electrode is disposed in the non-driving region.

5. The piezoelectric element according to any one of claims 1 to 4, a wiring portion electrically connected to the first external electrode and the second external electrode.

6. the element body has a plurality of first recesses each having a bottom and extending in the second direction, The drive device according to claim 5 , wherein the first drive portions and the second drive portions arranged alternately in the third direction are separated by the first recess.

7. The drive device according to claim 6 , wherein the element body portion separated by the first recess is continuous in the second direction.

8. 7. The drive device of claim 6, wherein the element body portion separated by the first recess is separated by a second recess having a bottom extending in the third direction into a first element body portion in which the first drive unit is located and a second element body portion in which the second drive unit is located.

9. the first external electrode electrically connected to the first internal electrode of the first driving unit is located on one end surface of the element body in the second direction, the first external electrode electrically connected to the first internal electrode of the second drive unit is located on the other end surface of the element body in the second direction, The driving device according to claim 8, wherein the second external electrode electrically connected to the second internal electrode of the first driving unit and the second internal electrode of the second driving unit is located on an inner wall surface of the second recess and on an end surface of the element body in the third direction that is continuous with the inner wall surface.

10. The driving device according to claim 5 , further comprising a base substrate electrically connected to the second external electrode.

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