JP6277863B2 - Multilayer piezoelectric element - Google Patents

Description

  The present invention relates to a multilayer piezoelectric element.

  Patent Document 1 discloses, for example, a multilayer piezoelectric element used for an ink discharge head provided in an ink jet printer. The laminated piezoelectric element includes a laminated body in which piezoelectric layers are laminated, a common external electrode, and a plurality of individual external electrodes. The multilayer body includes a base, a plurality of driving units and a pair of non-driving units extending from the main surface of the base along the stacking direction of the piezoelectric layers. The stacked body has first and second side surfaces facing each other in a direction orthogonal to the stacking direction. The first side surface forms one side surface of the base portion, the plurality of driving portions, and the pair of non-driving portions, and the second side surface includes other side surfaces of the base portion, the plurality of driving portions, and the pair of non-driving portions. There is no.

  The plurality of drive units and the pair of non-drive units are orthogonal to both the stacking direction and the opposing direction of the first and second side surfaces so that the plurality of drive units are positioned between the pair of non-drive units. It is lined up along the direction. In the plurality of drive units, the first internal electrodes and the second internal electrodes are alternately arranged along the stacking direction with the piezoelectric layers interposed therebetween. In the pair of non-driving portions, the piezoelectric layers and the third internal electrodes are alternately arranged along the stacking direction.

  One end of the first internal electrode is exposed on the first side surface, but the other end of the first internal electrode is not exposed on the second side surface. One end of the second internal electrode is not exposed on the first side surface, but the other end of the second internal electrode is exposed on the second side surface. One end and the other end of the third internal electrode are exposed at the first and second side surfaces, respectively.

  The common external electrode is disposed on the first side surface of the multilayer body, and is connected to one end of the first internal electrode and one end of the third internal electrode. The individual external electrodes are disposed on the other side surfaces of the plurality of drive units and the pair of non-drive units, and are connected to the other end of the second internal electrode and the other end of the third internal electrode. Therefore, the first and third internal electrodes have the same polarity. The first and third internal electrodes and the second internal electrode have different polarities.

JP 2003-250281 A (Patent No. 4225292)

  In the multilayer piezoelectric element described in Patent Document 1, the current flows in the order of the first internal electrode, the common external electrode, the third internal electrode, and the individual external electrode of the non-driving unit. Therefore, the first conductive path from the first internal electrode of the driving unit located on the center side in the direction in which the plurality of driving units and the pair of non-driving units are arranged to the individual external electrode of the non-driving unit is in the arrangement direction. The second conductive path from the first internal electrode of the driving unit located near the non-driving unit to the individual external electrode of the non-driving unit is longer by the distance from the non-driving unit. Therefore, the resistance value of the first conductive path is larger than that of the second conductive path. Therefore, as a result of the time constant of the equivalent circuit being different for each drive unit, the response of each drive unit is different, and the displacement when each drive unit is driven may vary.

  Accordingly, an object of the present invention is to provide a multilayer piezoelectric element capable of suppressing variation in displacement of a drive unit.

A multilayer piezoelectric element according to one aspect of the present invention includes a base, and a non-driving part and a plurality of driving parts respectively extending from the base in the same direction, and the plurality of piezoelectric layers are one. Comprising a laminated body laminated along the direction of the first and third external electrodes, the laminated body has first and second side surfaces facing each other in a direction orthogonal to one direction, The first side surface constitutes one side surface of each of the base portion, the non-driving portion, and the plurality of driving portions, and the second side surface constitutes another side surface of each of the base portion, the non-driving portion, and the plurality of driving portions, The drive unit includes first and second internal electrodes that face each other in one direction via the piezoelectric layer, and the base unit extends from one side surface of the base unit to the other side surface along a plane orthogonal to the one direction. A plurality of driving parts and a non-driving part having one direction, the first and the first electrodes. Line along the direction orthogonal to both of the opposing direction of the side surfaces, the first external electrodes, base, like over each aspect of the plurality of driving portions及beauty non-driving unit, a first side surface The second external electrode is disposed on each of the other side surfaces of the plurality of driving units, and the third external electrode is disposed on the other side of the non-driving unit so as to be electrically insulated from the second external electrode. The first internal electrode is connected to the first external electrode and is not connected to the second and third external electrodes, and the second internal electrode is connected to the second external electrode. Connected to the electrode and not connected to the first and third external electrodes, the third internal electrode is connected to the first and third external electrodes, and connected to the second external electrode It has not been.

  In the multilayer piezoelectric element according to one aspect of the present invention, the base has a third internal electrode extending from one side surface of the base portion to the other side surface along a surface orthogonal to one direction. The third internal electrode is connected to the first and third external electrodes. Therefore, a current flows between the first external electrode and the third external electrode of each drive unit via the third internal electrode of the base. That is, in the multilayer piezoelectric element according to one aspect of the present invention, compared with the conventional multilayer piezoelectric element in which a current flows through the common external electrode positioned on the outer surface of the multilayer body, Each conductive path from the electrode to the third external electrode is shortened. As a result, the difference in resistance value in each conductive path is reduced. As described above, since the time constants of the equivalent circuits of the respective drive units are all equal, the responsiveness of the respective drive units is equalized, so that variation in the displacement of the drive unit can be suppressed.

  The laminate has a first main surface, and the first main surface forms a part of an outer surface of the base portion that extends so as to connect one side surface of the base portion to the other side surface of the base portion. A first virtual plane that includes the first and second internal electrodes closest to the base, and a first virtual plane that includes the third internal electrode and overlaps the first virtual plane when viewed from one direction. The linear distance in one direction with the two virtual planes may be smaller than the linear distance in one direction between the first main surface and the second virtual plane. In this case, the position of the third internal electrode approaches the driving unit. Therefore, each conductive path becomes shorter, so that it is possible to further suppress variation in displacement of the drive unit. Further, in this case, since the linear distance in one direction between the third internal electrode and the first main surface becomes larger, one of the base portion between the third internal electrode and the first main surface is one. The thickness in the direction increases. Therefore, since the strength of the base portion is increased, it is possible to suppress the warpage of the multilayer piezoelectric element.

  The base may include a plurality of third internal electrodes that face each other in one direction via the piezoelectric layer. In this case, even when one of the plurality of third internal electrodes is cut when forming the drive unit by processing, each conductive path is constituted by the other third internal electrodes that are not cut. . Therefore, the yield of the multilayer piezoelectric element can be improved. Moreover, since the base has a plurality of third internal electrodes, the strength of the base is increased. For this reason, it is possible to suppress the warpage of the multilayer piezoelectric element.

  The base has a plurality of third internal electrodes facing in one direction via the piezoelectric layer, and the stacked body has first and second main surfaces facing in one direction, and the first The main surface is a surface that extends to connect one side surface of the base portion and the other side surface of the base portion, and forms a part of the outer surface of the base portion. The second main surface is the non-driving portion of the base portion. A side surface that forms a part of the outer surface of the non-driving part and extends so as to connect one side face and the other side face of the non-driving part, and one side face of the plural driving parts and the plural driving parts A part of the outer surface of the plurality of drive units that extends to connect to the other side surface, and includes an electrode closest to the first main surface among the plurality of third internal electrodes A second virtual plane including an electrode closest to the second main surface among the plurality of third internal electrodes and overlapping the first virtual plane when viewed from one direction; The linear distance in one direction with respect to the virtual plane is the third virtual plane including the electrode closest to the first main surface among the first and second internal electrodes and the first and second internal electrodes. It may be 30% to 55% of the linear distance in one direction including the electrode closest to the second main surface and the fourth virtual plane overlapping with the third virtual plane when viewed from one direction. In order to suppress the warp that may occur in the multilayer piezoelectric element, the thicker the base in one direction and the more the base has more third internal electrodes, the more effective, the multilayer piezoelectric element This leads to an increase in device size and cost. On the other hand, even if the base has a large number of third internal electrodes, the effect of suppressing the resistance value in each conductive path is saturated. Therefore, by setting the numerical value range of 30% to 55%, it is possible to balance each element of warpage suppression, resistance value suppression in each conductive path, miniaturization, and cost.

  According to the multilayer piezoelectric element according to the present invention, it is possible to suppress variation in displacement of the drive unit.

FIG. 1 is a perspective view of a multilayer piezoelectric element as viewed from above. FIG. 2 is a perspective view of the multilayer piezoelectric element as viewed from below. FIG. 3 is a front view of the multilayer piezoelectric element viewed from the direction of arrow III in FIG. 4 is a rear view of the multilayer piezoelectric element as seen from the direction of arrow IV in FIG. 5A shows a cross section taken along the line VA-VA in FIG. 1, and FIG. 5B shows a cross section taken along the line VB-VB in FIG. FIG. 6 is an enlarged perspective view showing the drive unit. FIG. 7 is a sectional view taken along line VII-VII in FIG. FIG. 8 is a diagram for explaining the conductive path. In a laminated piezoelectric element according to another example, FIG. 9A shows a cross section taken along line VA-VA in FIG. 1, and FIG. 9B shows a cross section taken along line VB-VB in FIG. Indicates.

  Embodiments of the present invention will be described with reference to the drawings. However, the following embodiments are exemplifications for explaining the present invention and are not intended to limit the present invention to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  The multilayer piezoelectric element 1 includes a multilayer body 2 and external electrodes 3 to 5. The length of the multilayer piezoelectric element 1 (the size in the X-axis direction in FIGS. 1 to 4) may be set to about 36.95 mm to 37.05 mm, for example. The width of the multilayer piezoelectric element 1 (the size in the Y-axis direction in FIGS. 1 to 4) may be set to about 1.85 mm to 1.95 mm. The thickness (size in the Z-axis direction in FIGS. 1 to 4) of the multilayer piezoelectric element 1 may be set to about 0.95 mm to 1.05 mm.

  The laminate 2 is formed by laminating a plurality of piezoelectric layers 30. The laminate 2 has a pair of end surfaces 2a and 2b, a pair of main surfaces 2c and 2d, and a pair of side surfaces 2e and 2f. The end faces 2 a and 2 b are opposed in the longitudinal direction of the stacked body 2. The opposing direction of the end faces 2a and 2b is the longitudinal direction of the stacked body 2, and is the X-axis direction of FIGS. The end faces 2a and 2b extend substantially parallel to each other and are substantially orthogonal to the X-axis direction.

  The main surfaces 2c and 2d are opposed to each other in the thickness direction of the stacked body 2. The opposing direction of the main surfaces 2c and 2d is the thickness direction of the stacked body 2, and is the Z-axis direction of FIGS. The main surfaces 2c and 2d extend substantially parallel to each other and are substantially orthogonal to the Z-axis direction. The main surfaces 2c and 2d connect the end surfaces 2a and 2b.

  The side surfaces 2 e and 2 f are opposed to each other in the width direction of the stacked body 2. The opposing direction of the side surfaces 2e and 2f is the width direction of the stacked body 2, and is the Y-axis direction of FIGS. The side surfaces 2e and 2f extend substantially parallel to each other and are substantially orthogonal to the Y-axis direction. The side surfaces 2e and 2f connect the end surfaces 2a and 2b and the main surfaces 2c and 2d.

  The stacked body 2 has eight first portions 10 and two second portions 11. The first and second portions 10 and 11 are arranged along the X-axis direction. The first portion 10 is located between the second portions 11 in the X-axis direction. That is, the second portion 11 is located on both ends in the X-axis direction. The first and second portions 10 and 11 are separated from each other. The number of the first and second portions 10 and 11 is not limited to the number described above, and may be at least one each.

  As shown in FIGS. 1 and 2, the first portion 10 includes a drive unit 50 and a part of a base 51. In any first portion 10, the drive unit 50 extends in the same direction from the base 51 along the Z-axis direction. The drive unit 50 and the base 51 are integrally formed. The drive unit 50 includes a piezoelectrically active active part (active region).

  The drive unit 50 has a rectangular shape when viewed from the Y-axis direction and the Z-axis direction. One of the side surfaces of the drive unit 50 that face each other in the Y-axis direction forms part of the side surface 2e. Of the side surfaces of the drive unit 50 that face each other in the Y-axis direction, the other side surface forms part of the side surface 2f. One side surface of the drive unit 50 facing in the Z-axis direction connects one side surface and the other side surface of the drive unit 50 and forms a part of the main surface 2c.

  The length of the drive unit 50 in the Y-axis direction is longer than the length of the drive unit 50 in the X-axis direction. Slits S are formed between adjacent drive units 50 with substantially equal intervals. Therefore, in the present embodiment, there are nine slits S. The slit S opens to the main surface 2c side and extends in the Z-axis direction.

  As shown in detail in FIG. 5A and FIG. 6, the drive unit 50 includes a plurality of piezoelectric layers 30 and a plurality of internal electrodes 31 and 32 having a rectangular shape. The piezoelectric layer 30 and the internal electrodes 31 and 32 are stacked in the Z-axis direction. The stacking direction of the piezoelectric layer 30 and the internal electrodes 31 and 32 (hereinafter referred to as the stacking direction) is the facing direction of the main surfaces 2c and 2d, the thickness direction of the stacked body 2, and is shown in FIGS. It is the Z-axis direction.

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 ). 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 may be set to about 10 μm to 50 μm.

  The plurality of internal electrodes 31 are arranged along the stacking direction so as to face each other in the stacking direction. The internal electrodes 31 extend substantially parallel to each other and are substantially orthogonal to the Z-axis direction. The number of internal electrodes 31 is not particularly limited, but is 10 in FIGS. 5A and 6. One end of the internal electrode 31 extends to the side surface 2e and is exposed to the side surface 2e. The other end of the internal electrode 31 extends to the vicinity of the side surface 2f, but is separated from the side surface 2f in the opposing direction of the side surfaces 2e and 2f. Therefore, the other end of the internal electrode 31 is not exposed on the side surface 2f.

  The plurality of internal electrodes 32 are arranged along the stacking direction so as to face each other in the stacking direction. The internal electrodes 32 extend substantially parallel to each other and are substantially orthogonal to the Z-axis direction. The number of internal electrodes 32 is not particularly limited, but is 10 in FIG. 5A and FIG. One end of the internal electrode 32 extends to the side surface 2f and is exposed to the side surface 2f. The other end of the internal electrode 32 extends to the vicinity of the side surface 2e, but is separated from the side surface 2e in the opposing direction of the side surfaces 2e and 2f. Therefore, the other end of the internal electrode 32 is not exposed on the side surface 2e.

  The internal electrodes 31 and 32 may be made of a conductive material containing silver (Ag) and palladium (Pd) as main components. The thickness of the internal electrodes 31 and 32 may be set to about 0.5 μm to 3 μm, for example. Cu (copper) may be used as the conductive material. The interval between the adjacent internal electrodes 31 and 32 in the stacking direction is set to, for example, about 10 μm to 50 μm, that is, approximately the same as the thickness of the piezoelectric layer 30 positioned between the adjacent internal electrodes 31 and 32. It may be set to about 20 μm.

  The internal electrodes 31 and the internal electrodes 32 are alternately arranged in the stacking direction. As shown in FIG. 6, the internal electrodes 31 and 32 have a portion P that overlaps in the stacking direction and a portion Q that does not overlap in the stacking direction. The portion P is a portion corresponding to the active portion in the drive unit 50. The portion Q is a portion corresponding to the inactive portion in the drive unit 50.

  As shown in FIGS. 1 and 2, the second portion 11 includes a non-drive portion 52 and a part of the base portion 51. In any second portion 11, the non-driving portion 52 extends from the base portion 51 in the same direction along the Z-axis direction. The direction in which the non-driving unit 52 extends from the base 51 is the same as the direction in which the driving unit 50 extends from the base 51. The non-driving part 52 and the base part 51 are integrally formed. The non-drive unit 52 includes an inactive portion (inactive region) that is piezoelectrically inactive.

  One side surface of the non-driving portion 52 facing in the Y-axis direction forms part of the side surface 2e. The other side of the non-driving portion 52 facing in the Y-axis direction forms part of the side surface 2f. One side surface of the non-driving portion 52 facing in the Z-axis direction connects one side surface and the other side surface of the non-driving portion 52, and forms a part of the main surface 2c. A groove 35 extending in the Z-axis direction is formed on the side surface 2e side of the non-drive portion 52.

  As shown in detail in FIG. 5B, the non-drive unit 52 includes a plurality of piezoelectric layers 30 and a plurality of internal electrodes 33 having a rectangular shape. The piezoelectric layer 30 and the internal electrode 33 are stacked in the Z-axis direction. The stacking direction of the piezoelectric layer 30 and the internal electrode 33 is substantially the same as the stacking direction of the piezoelectric layer 30 and the internal electrodes 31 and 32.

  The plurality of internal electrodes 33 are arranged along the stacking direction so as to face each other in the stacking direction. The internal electrodes 33 are adjacent to and face each other with the piezoelectric layer 30 interposed therebetween. The internal electrodes 33 extend substantially parallel to each other and are substantially orthogonal to the Z-axis direction. The number of internal electrodes 33 is not particularly limited, but is 20 in FIG. One end of the internal electrode 33 extends to the side surface 2f and is exposed to the side surface 2f. The other end of the internal electrode 33 extends to the side surface 2e and is exposed to the side surface 2e.

  The internal electrode 33 may be made of a conductive material containing silver (Ag) and palladium (Pd) as main components. The thickness of the internal electrode 33 may be set to about 0.5 μm to 3 μm, for example. Cu (copper) may be used as the conductive material. The linear distance between the adjacent internal electrodes 33 in the stacking direction may be set to, for example, about 10 μm to 50 μm, that is, about the same as the thickness of the piezoelectric layer 30 positioned between the adjacent internal electrodes 33, and set to about 20 μm. May be.

  The base 51 has a rectangular parallelepiped shape. One side surface of the base portion 51 that faces in the X-axis direction forms part of the end surface 2a. Of the side surfaces of the base portion 51 that face each other in the X-axis direction, the other side surface forms part of the end surface 2b. One of the side surfaces of the base portion 51 facing in the Y-axis direction forms part of the side surface 2e. Of the side surfaces of the base portion 51 that face each other in the Y-axis direction, the other side surface forms part of the side surface 2f. One side surface of the base portion 51 facing in the Z-axis direction connects one side surface and the other side surface of the base portion 51 and forms a part of the main surface 2d.

  As shown in FIGS. 2, 3, 5, and 6, the base 51 includes a plurality of piezoelectric layers 30 and internal electrodes 34. The piezoelectric layer 30 and the internal electrode 34 are stacked in the Z-axis direction. The stacking direction of the piezoelectric layer 30 and the internal electrode 34 is substantially the same as the stacking direction of the piezoelectric layer 30 and the internal electrodes 31 and 32.

  In the present embodiment, the number of internal electrodes 34 is one. As shown in detail in FIG. 7, the internal electrode 34 extends from one side surface of the base portion 51 to the other side surface along a surface orthogonal to the stacking direction in the base portion 51. In the present embodiment, the internal electrode 34 extends over substantially the entire area of the base 51 along a plane orthogonal to the stacking direction. The internal electrode 34 overlaps the driving unit 50 and the non-driving unit 52 when viewed from the stacking direction.

  As shown in FIG. 5A, the first virtual plane including the electrode (in this embodiment, the internal electrode 31) closest to the base 51 among the internal electrodes 31 and 32, and the second including the internal electrode 34. Is assumed to be overlapped when viewed from the stacking direction, the linear distance L1 in the stacking direction between the first virtual plane and the second virtual plane is set to 50 μm to 300 μm, for example. Also good. When it is assumed that the main surface 2d and the second virtual plane overlap each other when viewed from the stacking direction, the linear distance L2 in the stacking direction between the main surface 2d and the second virtual plane is, for example, 50 μm to 300 μm. It may be set. The straight line distance L1 may be set smaller than the straight line distance L2. In this case, the linear distance L1 may be set to about 50 μm to 250 μm, for example, and the linear distance L2 may be set to about 100 μm to 300 μm, for example.

  As shown in FIG. 7, both ends of the internal electrode 34 near the end faces 2a and 2b are not exposed from the end faces 2a and 2b, respectively. An end of the internal electrode 34 near the side surface 2e is exposed from a portion of the side surfaces 2e and 2f that constitutes the side surface of the non-driving unit 52. An end of the internal electrode 34 near the side surface 2f is exposed from the side surface 2f.

  As shown in FIGS. 1 to 3 and FIG. 5A, the external electrode 3 is disposed on each of the side surfaces 2 e of the driving unit 50. The external electrode 3 is physically and electrically connected to the end of the internal electrode 31 exposed at the side surface 2e. Each of the external electrodes 3 is physically and electrically independent from each other. The external electrode 3 may be made of, for example, a three-layer metal film of Cr, Cu / Ni, and Au. The thickness of the external electrode 3 may be set to about 0.3 μm to 5.0 μm, for example. Instead of the Au metal film, for example, Ag, Ag-Pd, Ag-Sn, or the like may be used.

  As shown in FIGS. 1, 2, 4, 5, and 7, the external electrode 4 is disposed over the entire surface of the side surface 2f. The external electrode 4 is physically and electrically connected to the end of the internal electrodes 32, 33, and 34 exposed at the side surface 2f. The external electrode 4 has a shape corresponding to the shape of the drive unit 50 and protrudes at a position corresponding to the drive unit 50 (see FIG. 4). The configuration of the external electrode 4 is the same as the configuration of the external electrode 3.

  As shown in FIG. 1 to FIG. 3, FIG. 5B and FIG. 7, the external electrode 5 is disposed on each of the side surfaces 2 e of the non-driving unit 52. The external electrode 5 is physically and electrically connected to the end of the internal electrodes 33 and 34 exposed at the side surface 2e. Each of the external electrodes 5 is physically and electrically independent from each other. The configuration of the external electrode 4 is the same as the configuration of the external electrode 3.

  In the X-axis direction, a cutout portion 36 in which the laminate 2 is cut out is formed at a corner portion between the two grooves 35 of the laminate 2 and between the side surface 2e and the main surface 2d. Is formed. The notch 36 is an inclined surface that is inclined with respect to the side surface 2e and the main surface 2d.

  In the multilayer piezoelectric element 1 configured as described above, the internal electrode 31 and the external electrode 3 are electrically connected and have the same polarity. The internal electrodes 32 to 34, the external electrode 4, and the external electrode 5 are electrically connected and have the same polarity. The internal electrode 31 and the external electrode 3 are not electrically connected to the internal electrodes 32 to 34 and the external electrodes 4 and 5.

  When a voltage is applied between the external electrode 3 and the external electrodes 4 and 5, a voltage is also applied between the internal electrode 31 and the internal electrode 32. Therefore, an electric field is generated in the piezoelectric layer 30 located in the active portion of the drive unit 50, and the drive unit 50 is displaced. On the other hand, in the non-driving unit 52, since the piezoelectric layer 30 is located between the internal electrodes 33, no electric field is generated in the piezoelectric layer 30. Therefore, the non-driving unit 52 is not displaced.

  Next, an example of 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 electrically conductive paste for electrode pattern formation is produced.

  Next, each of the electrode patterns corresponding to the internal electrodes 31 to 34 is formed on the green sheet by screen printing using a conductive paste. Then, a green sheet on which an electrode pattern corresponding to the internal electrode 31 and the internal electrode 33 is formed, a green sheet on which an electrode pattern corresponding to the internal electrode 32 and the internal electrode 33 is formed, and an electrode pattern corresponding to the internal electrode 34 are formed. The green sheet thus obtained and the green sheet to be the piezoelectric layer 30 are 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 of the laminate 2 to form external electrodes. And the external electrode is parted by forming the groove | channel 35 along the lamination direction in the surface corresponding to the side surface 2e in the laminated body 2. FIG. A notch 36 is formed at the corner between the side surface 2e and the main surface 2d of the laminate 2.

  Subsequently, the slit S is formed by a dicing blade, for example. Thus, the multilayer piezoelectric element 1 is obtained.

  In the present embodiment as described above, the base 51 has the internal electrode 34 extending from one side surface of the base 51 to the other side surface along a plane orthogonal to the stacking direction. The internal electrode 34 is connected to the external electrodes 4 and 5. Therefore, a current flows between the internal electrode 32 and the external electrode 5 of each drive unit 50 via the internal electrode 34 of the base 51. That is, as shown in FIG. 8, a conventional multilayer piezoelectric element in which current flows from the internal electrode 32 to the external electrode 5 through the external electrode 4 through the internal electrode 33 and along the conductive path D 2. In comparison, in the multilayer piezoelectric element 1 according to the present embodiment, each conductive path D1 from the internal electrode 32 of each drive unit 50 to the external electrode 5 is shortened as a whole. As a result, the difference in resistance value in each conductive path D1 is reduced. As described above, since the time constants of the equivalent circuits of the respective drive units 50 are all equal, the responsiveness of the respective drive units is equalized, so that variation in displacement of the drive unit 50 can be suppressed.

  When the linear distance L1 is set to be smaller than the linear distance L2 as in the present embodiment, the position of the internal electrode 34 approaches the driving unit 50. Therefore, since each conductive path D1 becomes shorter, it is possible to further suppress variation in the displacement of the drive unit 50. In this case, since the linear distance between the internal electrode 34 and the main surface 2d in the stacking direction is increased, the thickness of the base 51 in the stacking direction between the internal electrode 34 and the main surface 2d is increased. Therefore, since the strength of the base portion 51 is increased, it is possible to suppress the warpage of the multilayer piezoelectric element 1.

  As mentioned above, although embodiment of this invention was described in detail, you may add a various deformation | transformation to said embodiment within the range of the summary of this invention. For example, as shown in FIG. 9, the base 51 may have a plurality of internal electrodes 34 that face each other in the stacking direction with the piezoelectric layer 30 interposed therebetween. In this case, even when one of the plurality of internal electrodes 34 is cut when the drive unit 50 is formed by processing the slit S, each conductive path D1 is constituted by the other internal electrodes 34 that are not cut. The Therefore, the yield of the multilayer piezoelectric element 1 can be improved. Moreover, since the base 51 has the plurality of internal electrodes 34, the strength of the base 51 is increased. For this reason, it is possible to suppress the warpage of the multilayer piezoelectric element 1. The linear distance between the adjacent internal electrodes 34 in the stacking direction may be set to, for example, about 10 μm to 50 μm, that is, about the same as the thickness of the piezoelectric layer 30 positioned between the adjacent internal electrodes 34, and set to about 40 μm. May be. The number of internal electrodes 34 included in the base 51 is not particularly limited. For example, the number may be about 0.2 to 0.3 times the number of internal electrodes 31 and 32 included in the drive unit, or 4 to 6 sheets. It may be a degree.

  When the plurality of internal electrodes 34 are arranged on the base 51, the third virtual plane including the electrode closest to the main surface 2c among the plurality of internal electrodes 34 and the main surface 2d among the plurality of internal electrodes 34 When it is assumed that the fourth virtual plane including the close electrode overlaps, the linear distance L3 in the stacking direction between the third virtual plane and the fourth virtual plane may be set to 30 μm to 300 μm, for example. Good. It is assumed that the fifth virtual plane including the electrode closest to the main surface 2c of the internal electrodes 31 and 32 and the sixth virtual plane including the electrode closest to the main surface 2d of the internal electrodes 31 and 32 overlap. In this case, the linear distance L4 in the stacking direction between the fifth virtual plane and the sixth virtual plane may be set to 100 μm to 500 μm, for example. The straight line distance L3 may be 30% to 55% of the straight line distance L4. In order to suppress the warp that may occur in the multilayer piezoelectric element 1, the thicker the base 51 in the stacking direction and the more the base 51 has more internal electrodes 34, the more effective. This leads to an increase in size and cost of the element 1. On the other hand, even if the base 51 has a large number of internal electrodes 34, the effect of suppressing the resistance value in each conductive path D1 is saturated. Therefore, by setting the numerical value in the range of 30% to 55%, it is possible to balance each element of warpage suppression, resistance value suppression in each conductive path D1, miniaturization, and cost.

  DESCRIPTION OF SYMBOLS 1 ... Laminated piezoelectric element, 2 ... Laminated body, 2a, 2b ... End surface, 2c, 2d ... Main surface, 2e, 2f ... Side surface, 3-5 ... External electrode, 30 ... Piezoelectric layer, 31-34 ... Internal electrode , 50 ... drive unit, 51 ... base, 52 ... non-drive unit, L1 to L4 ... linear distance.

Claims (4)

A laminated body having a base and a non-driving part and a plurality of driving parts respectively extending from the base in the same direction, wherein a plurality of piezoelectric layers are laminated along the one direction; ,
First to third external electrodes,
The laminated body has first and second side surfaces facing each other in a direction orthogonal to the one direction,
The first side surface is a side surface of each of the base, the non-driving unit, and the plurality of driving units,
The second side surface constitutes another side surface of each of the base portion, the non-driving portion, and the plurality of driving portions,
The drive unit includes first and second internal electrodes facing in the one direction through the piezoelectric layer,
The base includes a third internal electrode extending from the one side surface of the base to the other side surface along a plane orthogonal to the one direction;
The plurality of driving units and the non-driving unit are arranged along a direction orthogonal to both the one direction and a facing direction of the first and second side surfaces,
The first external electrode, the base, so that over each of said one side of said plurality of driver and front Kihi driver, disposed on the first side surface,
The second external electrode is disposed on each of the other side surfaces of the plurality of driving units,
The third external electrode is disposed on the other side surface of the non-driving unit so as to be electrically insulated from the second external electrode;
The first internal electrode is connected to the first external electrode and not connected to the second and third external electrodes;
The second internal electrode is connected to the second external electrode and not connected to the first and third external electrodes;
The multilayer piezoelectric element, wherein the third internal electrode is connected to the first and third external electrodes and is not connected to the second external electrode. The laminate has a first main surface,
The first main surface is a surface that forms a part of the outer surface of the base portion, extending so as to connect the one side surface of the base portion and the other side surface of the base portion,
The first virtual plane including the electrode closest to the base portion of the first and second internal electrodes and the first virtual plane including the third internal electrode and overlapping the first virtual plane when viewed from the one direction. 2. The stacked type according to claim 1, wherein a linear distance in the one direction with the second virtual plane is smaller than a linear distance in the one direction between the first main surface and the second virtual plane. Piezoelectric element.   3. The multilayer piezoelectric element according to claim 1, wherein the base includes a plurality of the third internal electrodes that face each other in the one direction with the piezoelectric layer interposed therebetween. The base has a plurality of the third internal electrodes facing in the one direction via the piezoelectric layer,
The laminate has first and second main surfaces facing each other in the one direction,
The first main surface is a surface that forms a part of the outer surface of the base portion, extending so as to connect the one side surface of the base portion and the other side surface of the base portion,
The second main surface extends to connect the one side surface of the non-driving portion and the other side surface of the non-driving portion and forms a part of the outer surface of the non-driving portion. And a surface that forms a part of the outer surface of the plurality of drive units and extends to connect the one side surface of the plurality of drive units and the other side surface of the plurality of drive units. Yes,
A first virtual plane including an electrode closest to the first main surface among the plurality of third internal electrodes; and an electrode closest to the second main surface among the plurality of third internal electrodes. And the linear distance in the one direction with the second virtual plane that overlaps the first virtual plane when viewed from the one direction is the first main surface of the first and second internal electrodes. A third virtual plane including an electrode closest to the second virtual plane and an electrode closest to the second main surface among the first and second internal electrodes and the third virtual plane as viewed from the one direction. 3. The stacked piezoelectric element according to claim 1, wherein the linear piezoelectric element is 30% to 55% of a linear distance in the one direction with a fourth virtual plane that overlaps with the fourth virtual plane.

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