JP5821536B2 - Multilayer piezoelectric element - Google Patents

Description

  The present invention relates to a multilayer piezoelectric element.

  For example, a multilayer piezoelectric element described in Patent Document 1 is known. This multi-layer piezoelectric element has a drive unit in which piezoelectric layers and first and second drive internal electrodes are alternately stacked, and a connection unit in which piezoelectric layers and connection internal electrodes are stacked. A laminated body, a driving external electrode formed on one side of the laminated body and electrically connected to the first driving internal electrode, and a connecting external electrode formed on one side of the laminated body and electrically connected to the connecting internal electrode And a common external electrode formed on the other side surface of the laminate and electrically connected to the second drive internal electrode and the connection internal electrode.

JP 2003-037307 A

  In the multilayer piezoelectric element described above, the connection external electrode and the common external electrode are electrically connected by the connection internal electrode. In a piezoelectric actuator composed of such laminated piezoelectric elements, when this piezoelectric actuator is mounted, an actuator section (drive section) arranged at a position where the conduction path from the connection external electrode to the common external electrode is long. The resistance value of the common external electrode is larger than that of the actuator unit arranged at a position where the conduction path is short. As a result, the rise of the actuator arranged at a position where the conduction path is long is delayed as compared with the actuator part where the conduction path is short, so that there is a problem that the response varies in the actuator part.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a multilayer piezoelectric element that can make the displacement responsiveness in an actuator portion more uniform.

  The multilayer piezoelectric element according to the present invention includes a multilayer body, first, second, and third internal electrodes, and first, second, third, and fourth external electrodes. In the laminated body, a plurality of piezoelectric layers are laminated, and the first and second end faces facing each other and the first and second end faces are connected to each other and in the stacking direction of the plurality of piezoelectric layers. First and second main surfaces facing each other, and first and second side surfaces extending to connect the first and second main surfaces and facing each other. The first and second internal electrodes are alternately arranged in a first portion located between the first and second end faces of the multilayer body via at least one piezoelectric layer among the plurality of piezoelectric layers. Is done. The third internal electrode is disposed in the second portion located on the first end face side of the multilayer body.

  The first external electrode is provided on the first side surface and is connected to the first internal electrode. The second external electrode is provided on the second side surface and connected to the second and third internal electrodes. The third external electrode is provided on the first side surface so as to be electrically insulated from the first external electrode, and is connected to the third internal electrode. The fourth external electrode is provided on the second main surface so as to be electrically insulated from the first external electrode, and is connected to the third external electrode. The laminated body has a first cutout portion formed at a corner portion between the second side surface and the second main surface, and the second and fourth outer portions are connected by a connecting electrode provided on the first cutout portion. The electrodes are connected to each other.

  In the multilayer piezoelectric element according to the present invention, the second and fourth external electrodes are connected to each other by a connecting electrode provided on the first notch. That is, the second and fourth external electrodes are connected in a non-perpendicular state by the connecting electrode formed on the notch. In this case, the resistance between the second and fourth external electrodes decreases, the current flows from the second external electrode to the fourth external electrode, and the second and fourth external electrodes extend in the longitudinal direction. Both electrodes can be used efficiently. By using both external electrodes in this way, the resistance between the second internal electrode connected to the second external electrode and the third external electrode connected to the fourth external electrode is reduced. Regardless of the distance, it can be made more uniform and the resistance can be reduced. And it becomes possible to make the displacement responsiveness in an actuator part more uniform by low resistance.

  In the multilayer piezoelectric element described above, the second external electrode connected to the second internal electrode that is one of the constituent elements of the actuator section, and the third external electrode connected to the FPC or the like are the third. Are connected by internal electrodes. In this case, the second and third external electrodes are also connected by the third internal electrode, and between the second internal electrode connected to the second external electrode and the third external electrode The resistance can be made more uniform regardless of the distance.

  In the multilayer piezoelectric element described above, it is preferable that the thickness of the fourth external electrode is larger than the thickness of the second external electrode. In this case, the resistance of the current flowing through the fourth external electrode can be further reduced, and the resistance between the second internal electrode and the third external electrode can be further reduced.

  In the multilayer piezoelectric element described above, it is preferable that the connecting electrode is thicker than the second external electrode. In this case, the current flowing from the second external electrode to the fourth external electrode can be further increased, and both the second and fourth external electrodes can be used more efficiently.

  In the multilayer piezoelectric element described above, the multilayer body has a second notch formed at a corner portion between the first side surface and the second main surface in the first portion, and the first internal electrode and The fourth external electrode is preferably electrically insulated from each other by the second notch. In this case, the first external electrode can be sufficiently expanded to the second main surface side and the fourth external electrode can be sufficiently expanded to the first side surface, thereby reducing the respective resistance values. Can do. Further, when forming the first and fourth external electrodes, it is possible to omit the work of performing masking so that both electrodes are electrically insulated reliably. As a result, it is possible to easily manufacture a multilayer piezoelectric element.

  In the multilayer piezoelectric element described above, the cutout height h1 of the first cutout portion in the stacking direction may be smaller than the cutout height h2 of the second cutout portion in the stacking direction. The first cutout may be formed on the second main surface side in the stacking direction with respect to the lowermost layer of the second internal electrode. In this case, the second internal electrode can be reliably arranged.

  In the multilayer piezoelectric element described above, it is preferable that the second internal electrode is opposed to the second main surface. In this case, the layer is reliably inactivated between the second main surface and the second internal electrode, and power can be saved.

  In the multilayer piezoelectric element described above, a groove is formed between the first and third external electrodes on the first side surface of the multilayer body, and the first and third external electrodes are separated from each other by the groove. It is preferably electrically insulated. In this case, the first and third external electrodes can be reliably physically and electrically insulated without masking. As a result, it is possible to easily manufacture a multilayer piezoelectric element.

  ADVANTAGE OF THE INVENTION According to this invention, the lamination type piezoelectric element which can make the displacement responsiveness in an actuator part more uniform can be provided.

1 is a perspective view of a multilayer piezoelectric element according to a first embodiment of the present invention. (A) is the IIa-IIa sectional view taken on the line in FIG. 1, (b) is the IIb-IIb sectional view taken on the line in FIG. It is a perspective view of the piezoelectric actuator comprised from the lamination type piezoelectric element shown in FIG. It is a perspective view of the lamination type piezoelectric element concerning a 2nd embodiment of the present invention. It is the VV sectional view taken on the line in FIG. It is a perspective view of the piezoelectric actuator comprised from the laminated piezoelectric element shown in FIG. FIG. 7 is a perspective view when the piezoelectric actuator shown in FIG. 6 is viewed from an arrow VII. FIG. 7 is a perspective view when the piezoelectric actuator shown in FIG. 6 is viewed from an arrow VIII. It is sectional drawing which shows the example which changed the thickness of the external electrode of a piezoelectric element, (a) shows 2nd Embodiment, (b) shows the example where the thickness of an external electrode is the same, (c) is An example in which the bottom thickness of the external electrode is thicker than the others will be shown.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

[First Embodiment]
First, with reference to FIG.1 and FIG.2, the structure of the laminated piezoelectric element 1 which concerns on this embodiment is demonstrated. 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, a fourth external electrode 6, and a connection electrode 7. The first internal electrode 31, the second internal electrode 32, and the third internal electrode 33 are provided. For example, the multilayer piezoelectric element 1 has a length in the X direction set to about 37 mm, a width in the Y direction set to about 1.9 mm, and a thickness in the Z direction set to about 1 mm.

  The laminate 2 has a long and substantially rectangular parallelepiped shape, and includes first and second end surfaces 2a and 2b, first and second main surfaces 2c and 2d, and first and second side surfaces 2e, 2f. The first and second end faces 2a and 2b face each other in the longitudinal direction of the stacked body 2 and are parallel to each other. The first and second main surfaces 2c and 2d extend so as to connect the both end surfaces 2a and 2b, and face each other in the stacking direction (Z direction) of the piezoelectric layer 30 (described later). The first and second side surfaces 2e and 2f extend so as to connect both main surfaces 2c and 2d and face each other.

The multilayer body 2 is formed by laminating a plurality of piezoelectric layers 30 and 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 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. In the first portion 20, as shown in FIG. 2A, the first and second internal electrodes 31 and 32 are alternately stacked via the piezoelectric layers 30. The 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 ), and the thickness thereof is, for example, 10 μm to 50 μm. Degree. In the actual multilayer piezoelectric element 1, the piezoelectric layers 30 are integrated so as not to be visually recognized.

  A plurality of (in this case, four) first internal electrodes 31 are arranged at predetermined intervals in the stacking direction of the piezoelectric layers 30. One end of the first internal electrode 31 is drawn out to the first side face 2e, and is exposed to the first side face 2e. A plurality of (here, five) 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 surface 2f, and is exposed to the second side surface 2f. The first and second internal electrodes 31 and 32 are made of, for example, a conductive material mainly composed of silver (Ag) and palladium (Pd), and the thickness thereof is, for example, about 0.5 μm to 3 μm.

  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. When viewed in the stacking direction, the second internal electrode 32 is positioned on the first main surface 2c side and the second main surface 2d side, and the second internal electrode 32 positioned below is It faces the main surface 2d.

  The second portion 21a and the third portion 21b are portions including a piezoelectrically inactive region, and are located on the first end surface 2a side and the second end surface 2b side of the multilayer body 2, respectively. That is, the second portion 21a and the third portion 21b sandwich the first portion 20 in the longitudinal direction of the laminate 2 (the X direction that is the opposing direction of the first and second end faces 2a and 2b). Is provided. In the second portion 21a and the third portion 21b, as shown in FIG. 2B, the piezoelectric layers 30 and the 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 a predetermined interval 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 both side faces 2e and 2f. The third internal electrode 33 is physically and electrically insulated from the first and second internal electrodes 31 and 32. The third internal electrode 33 is a connection internal electrode that connects the second external electrode 4 and the third external electrodes 5a and 5b. The third internal electrode 33 is made of, for example, a conductive material mainly composed of silver (Ag) and palladium (Pd), and has a thickness of about 0.5 μm to 3 μm, for example.

  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. The first external electrode 3 is composed of a three-layer metal film of Cr, Cu / Ni, and Au. The external electrodes 4 to 6 and the connection electrode 7 described below are also made of the same material. The thickness of the first external electrode 3 is, for example, about 0.3 μm to 5.0 μm.

  The second external electrode 4 is provided on the second side surface 2f. The second external electrode 4 is formed over the entire surface of the 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 and third internal electrodes 32 and 33. The thickness of the second external electrode 4 is the same as that of the first external electrode 3 and is, for example, about 0.3 μm to 5.0 μm.

  The third external electrodes 5a and 5b are provided on the first side surface 2e. The third external electrodes 5a and 5b are located on the first side surface 2e at positions corresponding to the second portion 21a and the third portion 21b, that is, on both ends 2a and 2b in the longitudinal direction of the first side surface 2e. It is formed and is physically and electrically connected to one end of the third internal electrode 33. The third external electrodes 5a, 5b and the first external electrode 3 are electrically insulated from each other on the first side surface 2e. The thicknesses of the third external electrodes 5a and 5b are the same as those of the first and second external electrodes 3 and 4, and are, for example, about 0.3 μm to 5.0 μm.

  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 third external electrodes 5a and 5b at both ends thereof. The fourth external electrode 6 is electrically insulated from the first external electrode 3. The fourth external electrode 6 serves as a connection surface when connected to a substrate (support) or the like with an insulating adhesive. The thickness of the fourth external electrode 6 is formed to be about 2.5 to 3.3 times thicker than the other external electrodes 3, 4, 5 a and 5 b, for example, 0.75 μm to 3.3 μm. Degree.

  The connecting electrode 7 is provided on a cut-out surface 2g (first cut-out portion) at a corner portion between the second side surface 2f and the second main surface 2d. This notch surface 2g is formed over the entire longitudinal direction (X direction) of the laminate 2. The notch surface 2g is a notch portion having a height h1, and the upper end thereof is formed so as to be lower in the stacking direction than the second inner electrode 32 located at the lowest layer. That is, the notch surface 2g is formed on the second main surface 2d side in the stacking direction from the lowermost layer of the second internal electrode 32.

  The connection electrode 7 is formed over the entire cutout surface 2g, and connects the second external electrode 4 and the fourth external electrode 6 over the entire length thereof. Since the connecting electrode 7 is formed so as to be inclined at the corners of the side surface 2f and the main surface 2d orthogonal to each other, the flow of current between the external electrodes 4 and 6 orthogonal to each other is made smooth. Compared to the case where 4 and 6 are directly connected orthogonally, the resistance is reduced. The thickness of the connecting electrode 7 is formed to be about 1.2 to 2.4 times thicker than the other external electrodes 3, 4, 5 a, 5 b, for example, about 0.36 μm to 2.4 μm. . In the present embodiment, the connecting electrode 7 is formed to be thinner than the fourth external electrode 6, but may have a comparable thickness.

  Grooves 34 and 35 are formed between the first external electrode 3 and the second external electrodes 5a and 5b, respectively. That is, the grooves 34 and 35 are formed at a boundary portion between the first portion 20, the second portion 21a, and the third portion 21b. The grooves 34 and 35 are formed along the stacking direction of the piezoelectric layers 30 on the first side surface 2 e of the stacked body 2. By means of 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 surface 2 h (second notch portion) is provided at a corner portion between the first side surface 2 e and the second main surface 2 d. The notch surface 2h is formed along the longitudinal direction of the stacked body 2 at the corner portion between the first side surface 2e and the second main surface 2d, and is provided between the groove 34 and the groove 35. The notch surface 2h is a notch portion having a height h2, and the upper end thereof is formed so as to be lower in the stacking direction than the first inner electrode 31 located at the lowest layer. The cut surface 2h is an inclined surface that is inclined with respect to the side surface 2e and the main surface 2d. The first and fourth external electrodes 3 and 6 are physically and electrically insulated from each other by the cut surface 2h. The notch height h1 of the notch surface 2g is smaller than the notch height h2 of the notch surface 2h.

  Next, a piezoelectric actuator composed of the multilayer piezoelectric element 1 configured as described above will be described. FIG. 3 is a perspective view showing a piezoelectric actuator composed of the multilayer piezoelectric element shown in FIG. As shown in FIG. 3, the piezoelectric actuator 50 includes a plurality of (eight rows here) actuator portions 51 a to 51 h by slits S in which the first portion 20 of the multilayer piezoelectric element 1 extends parallel to the grooves 34 and 35. It is divided into The piezoelectric actuator 50 is used as, for example, a liquid discharge head of an ink jet printer.

  In the piezoelectric actuator 50, 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 actuator portions 51a to 51h, in the piezoelectric layer 30, an electric field is generated in a region between the first internal electrode 31 and the second internal electrode 32, and the region is displaced. At this time, in the second portion 21a and the third portion 21b, no displacement occurs in the piezoelectric layer 30 because no electric field is generated between the third internal electrodes 33.

  Next, a method for manufacturing the multilayer piezoelectric element 1 will be described.

  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 electroconductive 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. And the green sheet in which the electrode pattern corresponding to the 1st internal electrode 31 and the 3rd internal electrode 33 was formed, and the green in which the electrode pattern corresponding to the 2nd internal electrode 32 and the 3rd internal electrode 33 was formed A sheet and a green sheet to be the piezoelectric layer 30 are stacked to produce a stacked body green.

  Subsequently, the laminated 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. Then, the corner | angular part corresponding to the notch surface 2g is cut | disconnected along a longitudinal direction. And after degreasing the laminated body green at a predetermined temperature (for example, about 400 ° C.), the laminated body 2 is baked for a predetermined time at a predetermined temperature (for example, about 1100 ° C.).

  Subsequently, the second main surface 2d of the multilayer body 2 is turned down, and three layers of metal films of Cr, Cu / Ni, Au are blown toward the multilayer body 2 by sputtering from the lower side. The skipped material adheres not only to the second main surface 2d but also to the side surfaces 2e and 2f and the notch surface 2g, whereby external electrodes corresponding to the external electrodes 3 to 6 and the connection electrode 7 are formed. It is formed. Since the most sputtered material adheres to the second main surface 2d, as described above, the thickness of the fourth external electrode 6 formed on the second main surface 2d is different from that of the other external electrodes 3,3. Thicker than 4, 5a, 5b. Further, since many materials adhere to the notch surface 2g next to the second main surface 2d, the thickness of the connection electrode 7 formed on the notch surface 2g is also thicker than the external electrodes 3, 4, 5a, 5b. Become.

  And in the laminated body 2 in which the external electrode etc. were formed, by forming the groove | channels 34 and 35 along the lamination direction in the surface corresponding to the side surface 2e, an external electrode is parted and the 1st external electrode 3 and Third external electrodes 5a and 5b are formed. Further, by forming a notch surface 2h at the corner portion 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. Thus, the multilayer piezoelectric element 1 is obtained.

  As described above, in the multilayer piezoelectric element 1 according to this embodiment, the second and fourth external electrodes 4 and 6 are connected to each other by the connecting electrode 7 provided on the notch surface 2g. That is, the second and fourth external electrodes 4 and 6 are connected in a non-right angle state by the connecting electrode 7 formed on the notch surface 2g. For this reason, the resistance between the second and fourth external electrodes 4 and 6 decreases, the flow of current from the second external electrode 4 to the fourth external electrode 6 increases, and the second and fourth electrodes extending in the longitudinal direction. Both the fourth external electrodes 4 and 6 can be used efficiently. By using both the external electrodes 4 and 6 in this way, the second internal electrode 32 connected to the second external electrode 4 and the third external electrodes 5a and 5b connected to the fourth external electrode 6 are used. Can be lowered regardless of the distance. And by such resistance reduction, it becomes possible to make the displacement responsiveness in actuator part 51a-51h more uniform.

  In the multilayer piezoelectric element 1 described above, the second external electrode 4 connected to the second internal electrode 32 that is one of the components of the actuator portions 51a to 51h, and the third external electrode 4 connected to the FPC or the like. External electrodes 5 a and 5 b are connected by a third internal electrode 33. For this reason, the second and third external electrodes 4, 5 a, 5 b are also connected by the third internal electrode 33, and the second internal electrode 32 connected to the second external electrode 4 and the third The resistance between the external electrodes 5a and 5b can be made lower regardless of the distance.

  In the multilayer piezoelectric element 1, the thickness of the fourth external electrode 6 is larger than the thickness of the second external electrode 4. For this reason, the resistance of the current flowing through the fourth external electrode 6 can be further reduced, and the resistance between the second internal electrode 32 and the third external electrodes 5a and 5b can be further reduced. .

  In the multilayer piezoelectric element 1, the connecting electrode 7 is thicker than the second external electrode 4. For this reason, the current flowing from the second external electrode 4 to the fourth external electrode 6 can be further increased, and both the second and fourth external electrodes 4 and 6 can be used more efficiently. .

  In the multilayer piezoelectric element 1, the multilayer body 2 is formed with a notch surface 2h at a corner portion between the first side surface 2e and the second main surface 2d in the first portion 20, The internal electrode 31 and the fourth external electrode 6 are electrically insulated from each other by the notch surface 2h. For this reason, the first external electrode 3 can be sufficiently expanded to the second main surface 2d side, and the fourth external electrode 6 can be sufficiently expanded to the first side surface 2e side. Can be reduced. Further, when forming the first and fourth external electrodes 3 and 6, it is possible to omit the work of performing masking so that both electrodes are electrically insulated reliably. Thereby, the multilayer piezoelectric element 1 can be easily manufactured.

  In the multilayer piezoelectric element 1, the second internal electrode 32 is opposed to the second main surface 2d. For this reason, a layer becomes inactive reliably between the 2nd main surface 2d and the 2nd internal electrode 32, and it can be made power saving.

  In the multilayer piezoelectric element 1, the multilayer body 2 has grooves 34, 35 formed between the first and third external electrodes 3, 5a, 5b on the first side surface 2e. The third external electrodes 3, 5 a and 5 b are electrically insulated from each other by the grooves 34 and 35. For this reason, the first and third external electrodes 3, 5a, 5b can be physically and electrically insulated reliably without masking. Thereby, the multilayer piezoelectric element 1 can be easily manufactured.

[Second Embodiment]
Next, with reference to FIG.4 and FIG.5, the laminated piezoelectric element 60 which concerns on 2nd Embodiment is demonstrated. In the multilayer piezoelectric element 60 according to the present embodiment, in addition to the first portion 20, the first side surface 2e and the second main surface 2d of the multilayer body 62 also in the second portion 71a and the third portion 71b. And a notch surface 2i is formed. In the multilayer piezoelectric element 60, the third external electrodes 65a and 65b and the fourth external electrode 66 are divided by the notch surface 2i, and the two are not directly connected. Hereinafter, a description will be given focusing on differences from the first embodiment.

  The laminated piezoelectric element 60 includes a laminated body 62, a first external electrode 3, a second external electrode 4, third external electrodes 65 a and 65 b, a fourth external electrode 66, and a connection electrode 7. The first internal electrode 31, the second internal electrode 32, and the third internal electrode 33 are provided. As in the first embodiment, the laminate 62 includes first and second end surfaces 2a and 2b, first and second main surfaces 2c and 2d, and first and second side surfaces 2e and 2f. Have. The stacked body 62 includes a first portion 20, a second portion 71a, and a third portion 71b.

  The second portion 71a and the third portion 71b are portions including a piezoelectrically inactive region, and are located on the first end surface 2a side and the second end surface 2b side of the stacked body 62, respectively. The third external electrodes 65a and 65b are located on the first side surface 2e at positions corresponding to the second portion 71a and the third portion 71b, that is, on both ends 2a and 2b in the longitudinal direction of the first side surface 2e. It is formed and is physically and electrically connected to one end of the third internal electrode 33. The third external electrodes 65a and 65b and the first external electrode 3 are electrically insulated from each other on the first side surface 2e. The third external electrodes 65a and 65b are not directly connected to the fourth external electrode 66 by the cut-out surface 2i. The third external electrodes 65a and 65b are connected to the second external electrode 4 via the third internal electrode 33. Connected.

  The fourth external electrode 66 is provided on the second main surface 2d. The fourth external electrode 66 is formed over the entire surface of the second main surface 2d, and is connected to the second external electrode 4 by the connection electrode 7 over the entire longitudinal direction thereof. The thickness of the fourth external electrode 66 is formed to be about 2.5 to 3.3 times thicker than the other external electrodes 3, 4, 65a, 65b, as in the first embodiment. For example, it is about 0.75 μm to 3.3 μm. In addition, since the notch surface 2i is notched with the notch surface 2h, it is an inclined surface having the same inclination angle. However, the inclination angle of the notch surface 2i may be different from the notch surface 2h. Other configurations are the same as those in the first embodiment.

  Next, a piezoelectric actuator composed of the multilayer piezoelectric element 60 configured as described above will be described. 6 to 8 are perspective views showing a piezoelectric actuator composed of the multilayer piezoelectric element shown in FIG. As shown in FIGS. 6 to 8, the piezoelectric actuator 80 includes a plurality of (herein, eight rows) actuator portions in which the first portion 20 of the multilayer piezoelectric element 60 is formed by slits S extending in parallel with the grooves 34 and 35. It is divided into 81a to 81h.

  In the piezoelectric actuator 80, 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 actuator portions 81a to 81h, in the piezoelectric layer 30, an electric field is generated in a region between the first internal electrode 31 and the second internal electrode 32, and the region is displaced. At this time, in the second portion 71a and the third portion 71b, no electric field is generated between the third internal electrodes 33 in the piezoelectric layer 30, so that no displacement occurs.

  Here, the uniformity of the displacement responsiveness in the actuator portions 81a to 81h of the piezoelectric actuator 80 composed of the multilayer piezoelectric element 60 will be described. As shown in FIGS. 6 to 8, in the piezoelectric actuator 80, as in the first embodiment, the second external electrode 4 extending in the longitudinal direction is connected to the fourth external electrode by the connecting electrode 7 formed in an inclined shape. It is connected to the electrode 66 so that current can easily flow from the second external electrode 4 to the thick fourth external electrode 66, and both external electrodes 4 and 66 can be used effectively. For this reason, for example, the resistance between the inner actuator portion 81e and the third external electrodes 65a and 65b and the resistance between the outer actuator portion 81h and the third external electrodes 65a and 65b are substantially the same, that is, low resistance. Can be

  An example in which the conventional actuator configuration and the configuration of the present embodiment are compared with each other in terms of the lower resistance between the actuators 81a to 81h and the third external electrodes 65a and 65b will be described below. As shown in FIG. 9A, in the external electrode configuration of the actuator 80 according to the present embodiment, for example, the film thickness ratio (second external electrode: fourth external electrode) is 1: 2.5. When the combined resistance between the third external electrodes 65a and 65b is calculated, it is 2.26Ω, for example. On the other hand, as shown in FIG. 9B, the third external electrode has no connection electrode 7 and the film thickness ratio (second external electrode: fourth external electrode) is 1: 1. When the combined resistance between 65a and 65b is calculated, it becomes 2.91Ω, for example. Further, as shown in FIG. 9C, the third external electrode does not have the connecting electrode 7 and the film thickness ratio (second external electrode: fourth external electrode) is 1: 2.5. When the combined resistance between 65a and 65b is calculated, it becomes 2.41Ω, for example.

  As described above, also in the second embodiment, by using both the external electrodes 4 and 66 and the coupling electrode 7, the second internal electrode 32 connected to the second external electrode 4 and the third external electrode 65a. , 65b, the resistance can be made lower regardless of the distance. And by such resistance reduction, it becomes possible to make the displacement responsiveness in actuator part 81a-81h more uniform. In addition, in this embodiment, the other effect in 1st Embodiment can be show | played similarly.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, in the above embodiment, the case where the piezoelectric actuators 50 and 80 include eight rows of actuator portions 51a to 51h and 81a to 81h has been described as an example. However, the number of actuator portions need not be limited to these. The actuator may include 300 rows of actuator units. In this case, since the influence of the resistance value between the third external electrodes 5a, 5b, etc. and the second internal electrode 32 has a great influence on the responsiveness, the displacement responsiveness at the actuator portion can be provided by providing the above-described configuration. Can be made more uniform.

  In addition, as described above, the piezoelectric actuator composed of the multilayer piezoelectric element according to the present invention is effective when the surface on the second main surface 2d side is bonded to a pedestal or the like with an insulating adhesive. However, of course, it may be used when it is bonded to a conductive pedestal or the like with a conductive adhesive.

  DESCRIPTION OF SYMBOLS 1,60 ... Multilayer piezoelectric element 2,62 ... Laminated body, 2g ... Notch surface, 2h ... Notch surface, 3 ... 1st external electrode, 4 ... 2nd external electrode, 5a, 5b, 65a, 65b ... 3rd external electrode, 6, 66 ... 4th external electrode, 7 ... Connection electrode, 20 ... 1st part, 21a, 71a ... 2nd part, 21b, 71b ... 3rd part.

Claims (8)

A plurality of piezoelectric layers are stacked and extend so as to connect the first and second end faces facing each other and the first and second end faces and face each other in the stacking direction of the plurality of piezoelectric layers. A laminated body having first and second main surfaces, and first and second side surfaces extending so as to connect the first and second main surfaces and facing each other;
First and second alternatingly arranged in a first portion located between the first and second end faces of the multilayer body via at least one piezoelectric layer among the plurality of piezoelectric layers. An internal electrode;
A third internal electrode disposed on a second portion located on the first end face side of the laminate;
A first external electrode provided on the first side surface and connected to the first internal electrode;
A second external electrode provided on the second side surface and connected to the second and third internal electrodes;
A third external electrode provided on the first side surface to be electrically insulated from the first external electrode and connected to the third internal electrode;
A fourth external electrode provided on the second main surface so as to be electrically insulated from the first external electrode and connected to the third external electrode;
The laminated body has a first notch formed at a corner portion between the second side surface and the second main surface, and the second electrode is formed by a connecting electrode provided on the first notch. And the fourth external electrode are connected to each other, and the thickness of the fourth external electrode is larger than the thickness of the second external electrode . The multilayer piezoelectric element according to claim 1, wherein a thickness of the connection electrode is larger than a thickness of the second external electrode. A plurality of piezoelectric layers are stacked and extend so as to connect the first and second end faces facing each other and the first and second end faces and face each other in the stacking direction of the plurality of piezoelectric layers. A laminated body having first and second main surfaces, and first and second side surfaces extending so as to connect the first and second main surfaces and facing each other;
First and second alternatingly arranged in a first portion located between the first and second end faces of the multilayer body via at least one piezoelectric layer among the plurality of piezoelectric layers. An internal electrode;
A third internal electrode disposed on a second portion located on the first end face side of the laminate;
A first external electrode provided on the first side surface and connected to the first internal electrode;
A second external electrode provided on the second side surface and connected to the second and third internal electrodes;
A third external electrode provided on the first side surface to be electrically insulated from the first external electrode and connected to the third internal electrode;
A fourth external electrode provided on the second main surface so as to be electrically insulated from the first external electrode and connected to the third external electrode;
The laminated body has a first notch formed at a corner portion between the second side surface and the second main surface, and the second electrode is formed by a connecting electrode provided on the first notch. And the fourth external electrode are connected to each other, and the thickness of the connecting electrode is larger than the thickness of the second external electrode . In the laminate, a second notch is formed at a corner portion between the first side surface and the second main surface in the first portion,
4. The laminate according to claim 1, wherein the first internal electrode and the fourth external electrode are electrically insulated from each other by the second cutout portion. Type piezoelectric element.   5. The stacked mold according to claim 4, wherein a notch height h <b> 1 of the first notch in the stacking direction is smaller than a notch height h <b> 2 of the second notch in the stacking direction. Piezoelectric element.   The said 1st notch part is formed in the said 2nd main surface side in the said lamination direction rather than the lowest layer of the said 2nd internal electrode, The any one of Claims 1-5 characterized by the above-mentioned. The laminated piezoelectric element according to 1.   The multilayer piezoelectric element according to claim 1, wherein the second internal electrode is opposed to the second main surface. In the laminate, a groove is formed between the first and third external electrodes on the first side surface,
The multilayer piezoelectric element according to claim 1, wherein the first and third external electrodes are electrically insulated from each other by the groove.

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