JP5747685B2 - Piezoelectric element - Google Patents

Description

  The present invention relates to a piezoelectric element.

  As a conventional multilayer piezoelectric element, for example, one described in Patent Document 1 is known. The multilayer piezoelectric element described in Patent Document 1 has a driving unit in which piezoelectric layers and first and second driving internal electrodes are alternately stacked, and a piezoelectric layer and connecting internal electrodes are stacked. A laminated body having a connection portion; a driving external electrode formed on one side of the laminated body and electrically connected to the first driving internal electrode; and a connecting internal electrode formed on one side of the laminated body; An external electrode for connection that conducts, and a common external electrode that is formed on the other side surface of the laminate and is electrically connected to each of the second drive internal electrode and the connection internal electrode. In the drive part, a displacement part (actuator part) is constituted by a slit formed along the stacking direction from the upper surface side to the lower surface side of the piezoelectric layer.

JP 2003-37307 A

  By the way, the displacement part has a width of about several tens of μm. For this reason, when the displacement part is formed or when the piezoelectric element is handled, the displacement part may be bent from the base end side. In particular, the displacement portion is easily broken at the joint portion between the piezoelectric layer and the internal electrode on the base end side. Regarding this problem, if the displacement portion is formed wide to prevent the displacement portion from being broken, the capacitance increases in accordance with the increase in the facing area of the internal electrodes. As a result, there is a problem that current increases and power consumption increases.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a piezoelectric element that can prevent the displacement portion from being damaged while suppressing an increase in power consumption.

  In order to solve the above problems, a piezoelectric element according to the present invention is configured by alternately laminating a base portion constituted by a piezoelectric layer and first and second internal electrodes with the piezoelectric layer interposed therebetween. And a piezoelectric element comprising a laminate having a displacement portion extending from the base portion in the lamination direction of the first internal electrode and the second internal electrode, wherein the displacement portion is a first orthogonal to the lamination direction as seen from the lamination direction. The length of the direction is longer than the length of the second direction orthogonal to the first direction and the stacking direction, and the pair of end portions in the first direction and the first direction And a central portion located between the pair of end portions, wherein the width of at least one end portion in the second direction is wider than the width of the central portion in the second direction.

  In this piezoelectric element, the displacement portion has a pair of end portions in the first direction and a central portion located between the pair of end portions in the first direction, and the second portion of at least one end portion is the second portion. The width in the direction is wider than the width in the second direction at the center. Thereby, in the displacement part, the intensity | strength of the base part side is ensured in the at least one edge part of a 1st direction. Therefore, since the strength of the proximal end side of the easily foldable displacement portion is ensured, the displacement portion can be prevented from being damaged. In addition, since the end portion of the displacement portion in the first direction is formed wide, it is possible to suppress an increase in the facing area of the internal electrodes compared to a case where the width of the displacement portion is broadened and the strength is ensured. , Increase in capacitance can be suppressed. As a result, an increase in current can be suppressed, and an increase in power consumption can be suppressed.

  It is preferable that the first internal electrode and the second internal electrode have substantially the same width when viewed from the first direction. Since the first and second internal electrodes and the piezoelectric layer are made of different materials, the bonding strength between the first and second internal electrodes and the piezoelectric layer is lower than the bonding strength between the piezoelectric layers. Therefore, the joint between the first and second internal electrodes and the piezoelectric layer is easily broken. Therefore, by making the widths of the first internal electrode and the second internal electrode substantially the same, it is possible to increase the bonding area (adhesion area) between the piezoelectric layers at the end of the displacement portion in the first direction. it can. Therefore, the bonding strength at the displacement portion can be further ensured, and damage to the displacement portion can be further suppressed.

  According to the present invention, it is possible to prevent the displacement portion from being damaged while suppressing an increase in power consumption.

1 is a perspective view showing a multilayer piezoelectric element according to a first embodiment. It is the perspective view which looked at the lamination type piezoelectric element shown in Drawing 1 from the lower part. (A) is the sectional view on the aa line in FIG. 1, (b) is the sectional view on the bb line in FIG. (A) is a perspective view which shows a displacement part, (b) is a figure which shows an internal electrode. (A) is a perspective view which shows the displacement part of the multilayer piezoelectric element which concerns on 2nd Embodiment, (b) is a figure which shows the structure of the internal electrode arrange | positioned at the displacement part shown to (a). (A) is a perspective view which shows the displacement part of the laminated piezoelectric element which concerns on 3rd Embodiment, (b) is a figure which shows the structure of the internal electrode arrange | positioned at the displacement part shown to (a). (A) is a perspective view which shows the displacement part of the laminated piezoelectric element which concerns on 4th Embodiment, (b) is a figure which shows the structure of the internal electrode arrange | positioned at the displacement part shown to (a). (A) is a perspective view which shows the displacement part of the multilayer piezoelectric element which concerns on 5th Embodiment, (b) is a figure which shows the structure of the internal electrode arrange | positioned at the displacement part shown to (a). (A) is a perspective view which shows the displacement part of the multilayer piezoelectric element which concerns on 6th Embodiment, (b) is a figure which shows the structure of the internal electrode arrange | positioned at the displacement part shown to (a).

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

[First Embodiment]
FIG. 1 is a perspective view showing a multilayer piezoelectric element according to an embodiment of the present invention. FIG. 2 is a perspective view of the multilayer piezoelectric element shown in FIG. 1 as viewed from below. 3A is a cross-sectional view taken along the line aa in FIG. 1, and FIG. 3B is a cross-sectional view taken along the line bb in FIG.

  As shown in each drawing, the multilayer piezoelectric element 1 includes a multilayer body 2, a first external electrode 3, a second external electrode 4, third external electrodes 5 a and 5 b, and a fourth external electrode 6. ing. The multilayer piezoelectric element 1 has a length set to about 36.95 mm to 37.05 mm, a width set to about 1.85 mm to 1.95 mm, and a thickness set to about 0.95 mm to 1.05 mm, for example. Has been.

  The laminated body 2 extends so as to connect the pair of first and second end faces 2a, 2b facing the longitudinal direction of the laminated body 2 and the pair of first and second end faces 2a, 2b. A pair of first and second main surfaces 2c, 2d facing each other in the stacking direction of the piezoelectric layer 30 (described later) and the pair of first and second main surfaces 2c, 2d extend so as to connect to each other and face each other. It has a pair of first and second side surfaces 2e, 2f. In FIG. 1, the opposing direction of the pair of first and second end faces 2a, 2b is the X direction, the opposing direction of the pair of first and second side faces 2e, 2f is the Y direction, and the pair of first and second main faces 2c. , 2d is the Z direction.

  The stacked body 2 includes a first portion 20, a second portion 21a, and a third portion 21b. The first portion 20 is a portion including a piezoelectrically active active portion (active region), and is positioned between the first and second end faces 2 a and 2 b in the stacked body 2. Specifically, the first portion 20 is located at the central portion of the stacked body 2.

A displacement portion 50 is formed in the first portion 20. The displacement part 50 extends from the base part 51 configured by the piezoelectric layer 30 (is erected on the base part 51). The displacement part 50 and the base part 51 are integrally formed. In the displacement portion 50, the first internal electrodes 31 and the second internal electrodes 32 are alternately stacked with the piezoelectric layers 30 interposed therebetween. That is, the displacement part 50 extends from the base part 51 in the stacking direction of the first internal electrode 31 and the second internal electrode 32 (hereinafter simply referred to as the stacking direction). Each piezoelectric layer 30 is made of, for example, a piezoelectric ceramic material mainly composed of lead zirconate titanate (PZT: Pb (Zr _x , Ti _1-x ) O ₃ ). In the actual multilayer piezoelectric element 1, the piezoelectric layers 30 are integrated so as not to be visually recognized. In the present embodiment, the thickness of each piezoelectric layer 30 is about 10 μm to 50 μm.

  A plurality of (in this case, eight) displacement parts 50 are arranged in the X direction, and are spaced apart at a predetermined interval. The displacement part 50 is substantially I-shaped when viewed from the stacking direction (Z direction), and the length in the first direction (Y direction) orthogonal to the stacking direction is the first direction and the stacking direction. It is longer than the length in the second direction (X direction) perpendicular to each other. Moreover, the displacement part 50 is exhibiting the substantially rectangular shape seeing from the 1st direction.

  As shown in FIG. 4A, the displacement portion 50 has a width D1 at both end portions in the first direction wider than a width D2 at the center portion. Specifically, the displacement part 50 is comprised from the elongate center part 50a and a pair of edge part 50b, 50c. The central portion 50a is located between the pair of end portions 50b and 50c. The end portions 50b and 50c protrude from both ends of the central portion 50a in the first direction on both sides in the second direction (width direction) of the central portion 50a. That is, the width D1 of the both ends 50b and 50c of the displacement part 50 is wider than the width D2 of the center part 50a.

  A plurality (9 in this case) of grooves S formed at equal intervals are formed between the adjacent displacement portions 50. The groove S is formed so as to open to the first main surface 2c side and extend in the opposing direction of the first side surface 2e and the second side surface 2f.

  A plurality (six layers here) of the first internal electrodes 31 are arranged at a predetermined interval in the stacking direction of the piezoelectric layers 30. One end of the first internal electrode 31 is drawn out to the first side surface 2e, and is exposed to the first side surface 2e. A plurality (seven layers here) of the second internal electrodes 32 are arranged at a predetermined interval in the stacking direction of the piezoelectric layers 30. One end of the second internal electrode 32 is drawn out to the second side face 2f and is exposed to the second side face 2f. The first internal electrode 31 and the second internal electrode 32 are made of a conductive material mainly composed of silver (Ag) and palladium (Pd). In the present embodiment, the thickness of the first internal electrode 31 and the second internal electrode 32 is about 0.5 μm to 3 μm. Note that Cu (copper) can also be used as the conductive material.

  As shown in FIG. 4A, the first internal electrode 31 and the second internal electrode 32 have a first portion P that overlaps in the stacking direction and a second portion Q that does not overlap in the stacking direction. FIG. 4A shows portions corresponding to the first portion P and the second portion Q in the displacement portion 50.

  As shown in FIG. 4B, the first internal electrode 31 has a substantially T shape in a top view, and the width of one end portion in the first direction is wider than the width of the central portion. The second internal electrode 32 has the same configuration as the first internal electrode 31. That is, the second internal electrode 32 has a substantially T shape in a top view, and the width of one end portion in the first direction is wider than the width of the central portion.

  The first internal electrodes 31 and the second internal electrodes 32 are alternately arranged along the facing direction of the piezoelectric layers 30 so as to face each other with the piezoelectric layers 30 interposed therebetween. The second internal electrode 32 is located on the first main surface 2c side and the second main surface 2d side when viewed in the stacking direction.

  The second portion 21a and the third portion 21b are portions including a piezoelectrically inactive portion (inactive region), and are located on the first end surface 2a side and the second end surface 2b side of the laminate 2, respectively. ing. That is, the second portion 21a and the third portion 21b are provided so as to sandwich the first portion 20 in the longitudinal direction of the stacked body 2 (the opposing direction of the first and second end faces 2a and 2b). In the second portion 21a and the third portion 21b, a plurality of piezoelectric layers 30 and third internal electrodes 33 are alternately stacked. The second portion 21a and the third portion 21b have the same configuration.

  A plurality of (in this case, nine) third internal electrodes 33 are arranged at predetermined intervals in the stacking direction of the piezoelectric layers 30. One end of the third internal electrode 33 is drawn out to the first side face 2e, and the other end is drawn out to the second side face 2f, and is exposed to the first side face 2e and the second side face 2f. The third internal electrode 33 is physically and electrically insulated from the first internal electrode 31 and the second internal electrode 32. The third internal electrode 33 is a connection electrode that connects the second external electrode 4 and the third external electrodes 5a and 5b. The third internal electrode 33 is made of a conductive material containing silver (Ag) and palladium (Pd) as main components. In the present embodiment, the thickness of the third internal electrode 33 is about 0.5 μm to 3 μm.

  The first external electrode 3 is provided on the first side surface 2e. The first external electrode 3 is formed at a position corresponding to the first portion 20 on the first side surface 2 e and is physically and electrically connected to one end of the first internal electrode 31. Each of the first external electrodes 3 is physically and electrically independent from each other. The first external electrode 3 is made of a three-layer metal film of Cr, Cu / Ni, and Au. The thickness of the first external electrode 3 is about 0.3 μm to 5.0 μm. The configuration of this external electrode is the same for the second to fourth external electrodes 4 to 6. Instead of the Au metal film, Ag, Ag-Pd, or Ag-Sn can be used.

  The second external electrode 4 is provided on the second side surface 2f. The second external electrode 4 is formed over the entire second side surface 2 f and is physically and electrically connected to one end of the second internal electrode 32 and the third internal electrode 33. The second external electrode 4 is a common external electrode connected to both the second internal electrode 32 and the third internal electrode 33. The second external electrode 4 has a shape corresponding to the shape of the displacement portion 50, and has irregularities at a position corresponding to the displacement portion 50.

  The third external electrodes 5a and 5b are provided on the first side surface 2e. The third external electrodes 5a and 5b are formed at positions corresponding to the second portion 21a and the third portion 21b on the first side surface 2e, that is, at both ends in the longitudinal direction of the first side surface 2e. Is physically and electrically connected to one end of the. The third external electrodes 5a and 5b and the first external electrode 3 are electrically insulated from each other on the first side surface 2e.

  The fourth external electrode 6 is provided on the second main surface 2d. The fourth external electrode 6 is formed over the entire surface of the second main surface 2d, and is physically and electrically connected to the second external electrode 4 and the third external electrodes 5a and 5b. That is, the fourth external electrode 6 electrically connects the second external electrode 4 and the third external electrodes 5a and 5b. The fourth external electrode 6 is electrically insulated from the first external electrode 3. The fourth external electrode 6 is a connection electrode that connects the second external electrode 4 and the third external electrodes 5a and 5b. The fourth external electrode 6 serves as a connection surface when connected to a substrate (support) or the like with a conductive adhesive.

  Grooves 34 and 35 are formed between the first external electrode 3 and the third external electrodes 5a and 5b, respectively. That is, the grooves 34 and 35 are formed at the boundary between the first portion 20, the second portion 21a, and the third portion 21b. The grooves 34 and 35 are formed on the first side surface 2 e of the stacked body 2 along the stacking direction of the piezoelectric layers 30. By the grooves 34 and 35, the first external electrode 3 and the third external electrodes 5a and 5b are physically and electrically insulated.

  In the first portion 20 of the stacked body 2, a notch 36 is provided at a corner portion between the side surface 2 e and the main surface 2 d. The notch 36 is formed along the longitudinal direction of the laminate 2 at the corner between the side surface 2e and the main surface 2d, and is provided between the groove 34 and the groove 35. The notch 36 is an inclined surface that is inclined with respect to the side surface 2e and the main surface 2d. The first external electrode 3 and the fourth external electrode 6 are physically and electrically insulated by the notch 36.

  In the multilayer piezoelectric element 1, when a voltage is applied between the first external electrode 3 and the second external electrode 4, a voltage is also applied between the first internal electrode 31 and the second internal electrode 32. In the displacement portion 50 (first portion 20), an electric field is generated in a region between the first internal electrode 31 and the second internal electrode 32 in the piezoelectric layer 30, and the region is displaced. At this time, in the second portion 21 a and the third portion 21 b, no electric field is generated between the third internal electrodes 33 in the piezoelectric layer 30, so that no displacement occurs.

  Then, the manufacturing method of the multilayer piezoelectric element 1 which has the above-mentioned structure is demonstrated.

  First, a base paste is prepared by mixing an organic binder, an organic solvent, or the like with a piezoelectric ceramic material mainly composed of lead zirconate titanate, and a green sheet to be the piezoelectric layer 30 is formed using the base paste using a doctor blade method. Molded by Moreover, an organic binder, an organic solvent, etc. are mixed with the metal material which consists of silver and palladium of a predetermined ratio, and the electrically conductive paste for electrode pattern formation is produced.

  Next, each of the electrode patterns corresponding to the first to third internal electrodes 31 to 33 is formed on the green sheet by screen printing using a conductive paste. A green sheet on which electrode patterns corresponding to the first internal electrode 31 and the third internal electrode 33 are formed, a green sheet on which electrode patterns corresponding to the second internal electrode 32 and the third internal electrode 33 are formed, and piezoelectric A green sheet to be the body layer 30 is laminated to produce a laminate green.

  Subsequently, the laminate green is pressed at a predetermined pressure in the stacking direction while being heated at a predetermined temperature (for example, about 60 ° C.), and then the stacked green is cut into a predetermined size. The laminate green is degreased at a predetermined temperature (for example, about 400 ° C.) and then fired at a predetermined temperature (for example, about 1100 ° C.) for a predetermined time to obtain the stack 2.

  Subsequently, three layers of metal films of Cr, Cu / Ni, and Au are formed in this order on the surfaces corresponding to the side surfaces 2e and 2f and the main surface 2d of the multilayer body 2 to form external electrodes. Then, by forming grooves 34 and 35 along the stacking direction on the surface corresponding to the side surface 2e in the multilayer body 2, the external electrodes are divided to form the first external electrode 3 and the third external electrodes 5a and 5b. . In addition, by forming a notch 36 at the corner between the side surface 2e and the main surface 2d of the laminate 2, the external electrode is divided to form the first external electrode 3 and the fourth external electrode 6.

  Subsequently, the groove S is formed in the first portion 20 by, for example, laser light irradiation. Thereby, the displacement part 50 is comprised in the 1st part 20. As shown in FIG. Thus, the multilayer piezoelectric element 1 is obtained.

  As described above, in the multilayer piezoelectric element 1, the displacement portion 50 has a substantially I shape when viewed from the stacking direction, and the length in the first direction orthogonal to the stacking direction is the first direction. The width D1 of both end portions 50b and 50c in the first direction is longer than the width D2 of the central portion 50a.

  Thereby, in the displacement part 50, the intensity | strength by the side of the base 51 is ensured in the edge parts 50b and 50c of a 1st direction. Therefore, since the strength of the proximal end portion side of the easily deformable displacement portion 50 is ensured, the displacement portion 50 can be prevented from being damaged. In addition, since the end portions 50b and 50c in the first direction of the displacement portion 50 are formed wide, the first internal electrode 31 is larger than the case where the width of the displacement portion 50 is widened to ensure the strength. And the increase in the opposing area of the 2nd internal electrode 32 can be suppressed, and the increase in an electrostatic capacitance can be suppressed. As a result, an increase in current can be suppressed, and an increase in power consumption can be suppressed.

[Second Embodiment]
Next, the second embodiment will be described. FIG. 5A is a perspective view showing a displacement portion of the multilayer piezoelectric element according to the second embodiment, and FIG. 5B is a view of an internal electrode arranged in the displacement portion shown in FIG. It is a figure which shows a structure. As shown in FIG. 5, the displacement portion 50A formed in the first portion 20 is different from the first embodiment in the configuration of the first internal electrode 31 and the second internal electrode 32A. The displacement portion 50A includes a central portion 50Aa and end portions 50Ab and 50Ac.

  The first internal electrode 31A has substantially the same width when viewed from the first direction of the displacement portion 50A. That is, the first internal electrode 31A has a substantially rectangular shape, and both end portions of the first internal electrode 31A are aligned on a substantially straight line in the stacking direction. The second internal electrode 32A has substantially the same width when viewed from the first direction of the displacement portion 50A. That is, the first internal electrode 32A has a substantially rectangular shape, and both end portions of the second internal electrode 32A are aligned on a substantially straight line in the stacking direction. In addition, the substantially same thing said here may have the width | variety of 1st internal electrode 31A and 2nd internal electrode 32A, for example, and there may be a dimensional difference of about 0.01-0.1 micrometer, for example.

  In the displacement portion 50A, the widths of the first internal electrode 31A and the second internal electrode 32 are narrower than the widths of the end portions 50Ab and 50Ac at the end portions 50Ab and 50Ac. That is, in the end portions 50Ab and 50Ac of the displacement portion 50A, the first internal electrodes 31A and the second internal electrodes 32A are alternately stacked with the piezoelectric layer 30 interposed at the center in the second direction, and the second direction. The piezoelectric layer 30 is laminated at both ends of the.

  Here, since the first internal electrode 31A and the second internal electrode 32A and the piezoelectric layer 30 are made of different materials, the bonding strength between the first internal electrode 31A and the second internal electrode 32A and the piezoelectric layer 30 is piezoelectric. The bonding strength between the body layers 30 is low. Therefore, by making the widths of the first internal electrode 31A and the second internal electrode 32A substantially the same, the joining area between the piezoelectric layers 30 is increased at the end portions 50Ab and 50Ac of the displacement portion 50A. Therefore, in the displacement part 50A, the joining strength of the end parts 50Ab, 50Ac can be ensured, and damage can be prevented.

[Third Embodiment]
Subsequently, the third embodiment will be described. FIG. 6A is a perspective view showing a displacement portion of the multilayer piezoelectric element according to the third embodiment, and FIG. 6B is a view of an internal electrode arranged in the displacement portion shown in FIG. It is a figure which shows a structure. As shown in FIG. 6, the displacement portion 50 </ b> B formed in the first portion 20 has a substantially T shape when viewed from the stacking direction (Z direction), and a first direction (Y direction) orthogonal to the stacking direction. ) Is longer than the length in the second direction (X direction) orthogonal to the first direction and the stacking direction. Moreover, the displacement part 50B is exhibiting the substantially rectangular shape seeing from the 1st direction.

  The displacement part 50B is composed of a long central part 50Ba and end parts 50Bb and 50Bc. The end portion 50Bb protrudes on both sides in the second direction (width direction) of the central portion 50Ba on one end side (first side surface 2e or second side surface 2f side) in the first direction of the central portion 50Ba. . That is, the width D1 of the end portion 50Bb of the displacement portion 50B is wider than the width D2 of the center portion 50Ba. In the displacement portion 50B, the central portion 50Ba is a portion corresponding to the first portion P where the first internal electrode 31B and the second internal electrode 32B overlap in the stacking direction. Further, the end portions 50Bb and 50Bc are portions corresponding to the second portion Q where the first internal electrode 31B and the second internal electrode 32B do not overlap in the stacking direction.

  As shown in FIG. 6B, the first internal electrode 31B has a shape corresponding to the shape of the displacement portion 50B. That is, the first internal electrode 31B has a substantially T shape in a top view, and the width of one end portion in the first direction is wider than the width of the central portion. The second internal electrode 32B has the same configuration as the first internal electrode 31B. That is, the second internal electrode 32B has a substantially T shape in a top view, and the width of one end portion in the first direction is wider than the width of the central portion.

  As described above, the displacement portion 50B has a substantially T-shape when viewed from the stacking direction, and the length of the first direction orthogonal to the stacking direction is the second direction orthogonal to the first direction. In the first direction, the width D1 of the end portion 50Bb is wider than the width D2 of the central portion 50Ba.

  Thereby, in the displacement part 50B, the intensity | strength by the side of the base 51 is ensured in edge part 50Bb of a 1st direction. Therefore, since the strength of the proximal end portion side of the easily deformable displacement portion 50B is ensured, the displacement portion 50B can be prevented from being damaged. In addition, since the end portion 50Bb in the first direction of the displacement portion 50B is formed wide, the first internal electrode 31B and the first inner electrode 31B and the first inner electrode 31B are compared with the case where the width of the displacement portion 50B is widened to ensure the strength. 2 An increase in the facing area of the internal electrode 32B can be suppressed, and an increase in capacitance can be suppressed. As a result, an increase in current can be suppressed, and an increase in power consumption can be suppressed.

[Fourth Embodiment]
Subsequently, a fourth embodiment will be described. FIG. 7A is a perspective view showing a displacement portion of the multilayer piezoelectric element according to the fourth embodiment, and FIG. 7B is arranged at the displacement portion shown in FIG. It is a figure which shows the structure of an internal electrode. As shown in FIG. 7, the displacement portion 50 </ b> C has a substantially L shape when viewed from the stacking direction (Z direction), and the length in the first direction (Y direction) orthogonal to the stacking direction is first. This is longer than the length in the second direction (X direction) orthogonal to the direction and the stacking direction. Further, the displacement portion 50C has a substantially rectangular shape when viewed from the first direction.

  The displacement portion 50C is composed of a long central portion 50Ca and end portions 50Cb and 50Cc. The end portion 50Cb protrudes to one side in the second direction (width direction) of the central portion 50Ca on one end side (first side surface 2e or second side surface 2f side) of the central portion 50Ca in the first direction. Yes. That is, the width D1 of the end 50Cb of the displacement part 50 is wider than the width D2 of the central part 50Ca. In the displacement part 50C, the central part 50Ca is a part corresponding to the first part P where the first internal electrode 31C and the second internal electrode 32C overlap in the stacking direction. Further, the end portion 50Cb is a portion corresponding to the second portion Q where the first internal electrode 31C and the second internal electrode 32C do not overlap in the stacking direction.

  As shown in FIG. 7B, the first internal electrode 31C has a shape corresponding to the shape of the displacement portion 50C. That is, the first internal electrode 31C has a substantially L shape in a top view, and the width of one end portion in the first direction is wider than the width of the central portion. The second internal electrode 32C has the same configuration as the first internal electrode 31C. That is, the second internal electrode 32C has a substantially L shape in a top view, and the width of one end portion in the first direction is wider than the width of the central portion.

  As described above, the displacement portion 50C has a substantially L shape when viewed from the stacking direction, and the length of the first direction orthogonal to the stacking direction is the second direction orthogonal to the first direction. In the first direction, the width D1 of the end portion 50Cb is wider than the width D2 of the center portion 50Ca.

  Thereby, in the displacement part 50C, the strength on the base 51 side is ensured at the end part 50Cb in the first direction. Therefore, since the strength of the proximal end portion side of the easily deformable displacement portion 50C is ensured, the displacement portion 50C can be prevented from being damaged. In addition, since the end portion 50Cb in the first direction of the displacement portion 50C is formed wide, the first internal electrode 31C and the first inner electrode 31C and the first inner electrode 31C are compared with the case where the overall width of the displacement portion 50C is increased to ensure strength. 2 An increase in the facing area of the internal electrode 32C can be suppressed, and an increase in capacitance can be suppressed. As a result, an increase in current can be suppressed, and an increase in power consumption can be suppressed.

[Fifth Embodiment]
Subsequently, a fifth embodiment will be described. FIG. 8A is a perspective view showing a displacement portion of the multilayer piezoelectric element according to the fifth embodiment, and FIG. 8B is a view of an internal electrode arranged in the displacement portion shown in FIG. It is a figure which shows a structure. As shown in FIG. 8, the displacement part 50D has a substantially trapezoidal shape when viewed from the stacking direction (Z direction), and the length in the first direction (Y direction) orthogonal to the stacking direction is the first. This is longer than the length in the second direction (X direction) orthogonal to the direction and the stacking direction. Further, the displacement portion 50D has a substantially rectangular shape when viewed from the first direction.

  The displacement part 50D is comprised from center part 50Da and edge part 50Db, 50Dc. The displacement portion 50D becomes wider from the one end portion 50Dc side in the first direction toward the other end portion 50Db side. That is, in the displacement part 50D, the width D1 of the end part 50Db is wider than the width D2 of the center part 50Da, and the width of the end part 50Dc opposite to the end part 50Db is narrower than the width D2 of the center part 50Da (D1 > D2> D3). In the displacement part 50D, the central part 50Da is a part corresponding to the first part P where the first internal electrode 31D and the second internal electrode 32D overlap in the stacking direction. Further, the end portions 50Db and 50Dc are portions corresponding to the second portion Q where the first internal electrode 31D and the second internal electrode 32D do not overlap in the stacking direction.

  As shown in FIG. 8B, the first internal electrode 31D has a shape corresponding to the shape of the displacement portion 50D. That is, the first internal electrode 31D has a substantially trapezoidal shape in a top view, and becomes wider from one end side in the first direction toward the other end side. The second internal electrode 32D has the same configuration as the first internal electrode 31D. That is, the second internal electrode 32D has a substantially trapezoidal shape in a top view, and becomes wider from one end side in the first direction toward the other end side.

  As described above, the displacement portion 50D has a substantially trapezoidal shape when viewed from the stacking direction, and the length in the first direction orthogonal to the stacking direction is in the second direction orthogonal to the first direction. The width D1 of the end portion 50Db is wider than the width D2 of the center portion 50Da in the first direction.

  Thereby, in the displacement part 50D, the strength on the base part 51 side is secured at the end part 50Db in the first direction. Therefore, since the strength of the proximal end portion side of the easily deformable displacement portion 50D is ensured, the displacement portion 50D can be prevented from being damaged. Further, since the end portion 50Db in the first direction of the displacement portion 50D is formed wide, the first internal electrode 31D and the first inner electrode 31D and the first inner electrode 31D are compared with the case in which the width of the displacement portion 50D is widened to ensure strength. 2 An increase in the facing area of the internal electrode 32D can be suppressed, and an increase in capacitance can be suppressed. As a result, an increase in current can be suppressed, and an increase in power consumption can be suppressed.

[Sixth Embodiment]
Subsequently, a sixth embodiment will be described. FIG. 9A is a perspective view showing a displacement portion of the multilayer piezoelectric element according to the sixth embodiment, and FIG. 9B shows an internal electrode arranged in the displacement portion shown in FIG. 9A. It is a figure which shows a structure. As shown in FIG. 9, the displacement part 50E is comprised from the elongate center part 50Ea and edge part 50Eb, 50Ec.

The end portion 50Eb protrudes on both sides in the second direction (width direction) of the central portion 50Ea on one end side (second side surface 2f side) in the first direction of the central portion 50Ea, and the adjacent displacement portion It is connected to the end portion 50Eb of 50E. That is, the width D1 of the end portion 50Bb of the displacement portion 50E is wider than the width D2 of the center portion 50Ba. The width of the end portion 50Bc of the displacement portion 50E is the same as the width D2 of the central portion 50Ba. In the displacement portion 50E, the central portion 50Ea is a portion corresponding to the first portion P where the first internal electrode 31E and the second internal electrode 32E overlap in the stacking direction. The end portions 50Eb and 50Ec are portions corresponding to the second portion Q where the first internal electrode 31E and the second internal electrode 32E do not overlap in the stacking direction.

  With such a configuration, the displacement portion 50E has a substantially U-shape when viewed from the stacking direction. Moreover, the displacement part 50E is exhibiting substantially rectangular shape seeing from the 1st direction (1st side surface 2e side). As shown in FIG. 9B, the first internal electrode 31D has a rectangular shape in a top view. The second internal electrode 32D has a rectangular shape in a top view.

  As described above, the displacement portion 50E has a substantially U shape when viewed from the stacking direction, and the length of the first direction orthogonal to the stacking direction is the second direction orthogonal to the first direction. The width D1 of the end portion 50Eb is wider than the width D2 of the central portion 50Ea in the first direction.

  Thereby, in the displacement part 50E, the intensity | strength by the side of the base 51 is ensured in the edge part 50Eb of a 1st direction. Therefore, since the strength of the proximal end portion side of the easily deformable displacement portion 50E is ensured, the displacement portion 50E can be prevented from being damaged. Further, since the end portion 50Eb in the first direction of the displacement portion 50E is formed wide, the first internal electrode 31E and the first inner electrode 31E and the first inner electrode 31E are compared with the case where the entire width of the displacement portion 50E is widened to ensure strength. 2 An increase in the facing area of the internal electrode 32E can be suppressed, and an increase in capacitance can be suppressed. As a result, an increase in current can be suppressed, and an increase in power consumption can be suppressed.

  The present invention is not limited to the above embodiment. For example, in the said embodiment, although the laminated body 2 is set as the structure containing the 1st part 20, the 2nd part 21a, and the 3rd part 21b, the structure of the laminated body 2 is not limited to this.

  Moreover, in the said embodiment, although the 4th external electrode 6 which connects the 2nd external electrode 4 and the 3rd external electrodes 5a and 5b is formed in the 2nd main surface 2d of the laminated body 2, The electrode 6 may not be provided. That is, the connection between the second external electrode 4 and the third external electrodes 5a and 5b may be only the third internal electrode 33.

  In the second to fifth embodiments, the shape of the first and second internal electrodes is made to correspond to the shape of the displacement portion, but the shape of the first and second internal electrodes is from the first direction. It may be substantially the same as viewed. That is, the first and second internal electrodes may be substantially rectangular in top view. In this case, the bonding area (contact area) between the piezoelectric layers can be increased at the end of the displacement part in the first direction.

  DESCRIPTION OF SYMBOLS 1 ... Laminated piezoelectric element, 2 ... Laminated body, 2 ... Laminated body, 30 ... Piezoelectric layer, 31, 31A, 31B, 31C, 31D, 31E ... 1st internal electrode, 32, 32A, 32B, 32C, 32D, 32E: second internal electrode, 50, 50A, 50B, 50C, 50D, 50E: displacement part, 51: base part, D1: end width, D2: central part width.

Claims (3)

A base portion configured by a piezoelectric layer, and first internal electrodes and second internal electrodes are alternately stacked with the piezoelectric layer interposed therebetween, and the first internal electrode and the second internal electrode are formed from the base portion. A piezoelectric element comprising a laminate having a plurality of displacement portions extending in the laminating direction,
Each of the displacement portions has a length in a first direction orthogonal to the stacking direction, as viewed from the stacking direction, longer than a length in a second direction orthogonal to the first direction and the stacking direction. Having a shape and having a pair of end portions in the first direction and a central portion located between the pair of end portions in the first direction;
The plurality of displacement portions are juxtaposed in the second direction,
The piezoelectric element, wherein a width of at least one of the end portions in the second direction is wider than a width of the central portion in the second direction. Wherein when viewed from a first direction, said the width of the width and the second inner electrodes of the first internal electrode, the piezoelectric element according to claim 1, wherein the substantially identical. 2. The piezoelectric element according to claim 1, wherein the displacement portion becomes wider from one end portion in the first direction toward the other end portion as viewed from the stacking direction.

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