JP2006237252A - Piezoelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric element in which crosstalk between adjacent individual electrodes in an active layer, and deformation of an element to the side opposite to a displacement transmitting surface are prevented certainly. <P>SOLUTION: A multilayer piezoelectric element 1 comprises an active layer 2, and a restriction layer 4 laid in layer for the active layer 2. The active layer 2 has a piezoelectric 5, internal individual electrodes 6, and an internal common electrode 7 opposing each other while sandwiching the piezoelectric 5, and displaces when a voltage is applied between these electrodes 6 and 7. The restriction layer 4 has a plurality of piezoelectrics 8 laid in layers, and individual interconnection electrodes 9 and a common interconnection electrode 10 arranged between the piezoelectrics 8 of respective layers, and regulates displacement of the active layer 2 for one side. On the upper surface of the restriction layer 4, individual terminal electrodes 11 for applying a voltage to the internal individual electrodes 6, and a common terminal electrode 12 for applying a voltage to the internal common electrode 7 are provided. Each piezoelectric 8 is thicker than the piezoelectric 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezoelectric element including a piezoelectric body and a plurality of individual electrodes and a common electrode.

  As a conventional piezoelectric element, there is one described in Patent Document 1, for example. The laminated piezoelectric element described in this document is laminated on an active layer formed by alternately laminating a piezoelectric sheet having a plurality of individual electrodes and a piezoelectric sheet having a common electrode formed thereon. A surface electrode for the individual electrode and a surface electrode for the common electrode are formed on the surface of the insulating sheet. In such a laminated piezoelectric element, a driving object is arranged on the opposite side of the insulating sheet in the active layer. When a voltage is applied between the individual electrode and the common electrode via the surface electrode, a portion (piezoelectric active portion) between the individual electrode and the common electrode in the active layer is displaced in the stacking direction, and the driven object is Driven.

Here, as described in Patent Document 1, when a plurality of electrically independent individual electrodes are formed in a two-dimensional matrix in the element, a cross between piezoelectric active portions corresponding to adjacent individual electrodes is crossed. Talk may be a problem, and displacement (deformation) of the piezoelectric element with respect to the opposite side of the displacement transmission surface may be a problem, resulting in a decrease in the amount of displacement of the active layer. In order to solve such a problem, for example, as described in Patent Document 2, it is known to provide a constraining layer that restricts the displacement of the active layer on the opposite side of the displacement transmission surface across the active layer. It has been.
JP 2002-254634 A JP 2001-162696 A

  However, in recent years, further miniaturization of piezoelectric elements and higher density of individual electrodes are required. For this reason, simply providing a constraining layer as described in Patent Document 2 described above includes crosstalk between piezoelectric active portions corresponding to adjacent individual electrodes and deformation of the piezoelectric element on the opposite side of the displacement transmission surface. The problem cannot be solved. Further, in the piezoelectric element described in Patent Document 2, since the dummy electrode (floating electrode) is provided in the constraining layer, the constraining layer may move due to charge accumulation due to static electricity. As a result, crosstalk or the like between adjacent piezoelectric active portions may occur.

  An object of the present invention is to provide a piezoelectric element that can reliably prevent crosstalk between adjacent individual electrodes in an active layer and element deformation to the opposite side of a displacement transmission surface.

  The piezoelectric element of the present invention includes a plurality of individual electrodes and a common electrode facing each other with a first piezoelectric body interposed therebetween, an active layer that is displaced by applying a voltage between the individual electrode and the common electrode, and an active layer A constraining layer that is laminated to the layer and restricts the displacement of the active layer relative to one side of the active layer, and a plurality of layers for applying a voltage to each individual electrode provided on the surface of the constraining layer opposite to the active layer A first terminal electrode and a second terminal electrode for applying a voltage to the common electrode, and the constraining layer is disposed between the plurality of second piezoelectric bodies stacked on each other and each second piezoelectric body, Arranged between the plurality of first relay electrodes for electrically connecting the individual electrodes and the first terminal electrodes via the first through holes formed in the second piezoelectric body, and the second piezoelectric bodies. And the second electrode through the second through-hole formed in the second piezoelectric body. A second relay electrode for electrically connecting the child electrode, and the thickness of the second piezoelectric body adjacent to the active layer is larger than the thickness of the first piezoelectric body. .

  In a piezoelectric element having an active layer and a constraining layer as described above, in order to restrict the displacement of the active layer, it is better that the constraining layer is thick. However, if the constraining layer is unnecessarily thick, the size and cost of the element are increased. It is not preferable because it is connected. In addition, when the constraining layer is to be formed of a single layer of piezoelectric material, a large-diameter through hole is provided to ensure electrical connection between the individual electrode, common electrode, and terminal electrode by increasing the thickness of the piezoelectric material. Must be formed on the piezoelectric body. This is because the diameter of the through hole is generally made larger than the thickness of one layer of the piezoelectric body. When a through hole having a large diameter is formed in this way, it is difficult to increase the density of the individual electrodes, which is not preferable. For this reason, it is desirable that the constraining layer is formed by laminating a plurality of piezoelectric bodies having a small thickness. In this case, it is necessary to provide a relay electrode between the piezoelectric bodies of the respective layers in order to ensure electrical connection between the through holes formed in the piezoelectric bodies of the respective layers.

  However, as a result of intensive studies by the present inventors, when a constrained layer is formed by laminating a plurality of thin piezoelectric bodies, it is caused by the relay electrode, particularly when a plurality of individual electrodes are arranged at high density. It has been found that the electric field (capacitance) generated by this influences the crosstalk between adjacent individual electrodes and the deformation of the active layer on the side opposite to the displacement transmission surface of the piezoelectric element (constraint layer side). Specifically, when a voltage is applied between the individual electrode and the common electrode, an electric field is generated not only in a portion (piezoelectric active portion) between the individual electrode and the common electrode in the active layer, but also in the constraining layer. In other words, an electric field is also generated between the individual electrode or common electrode and the relay electrode in FIG. 2, so that a minute displacement occurs in the constraining layer, causing the above-described problem.

  Therefore, in the present invention, a plurality of second piezoelectric bodies are stacked to form a constraining layer, and a plurality of first relay electrodes and second relay electrodes are provided between the second piezoelectric bodies, and adjacent to the active layer. The thickness of the second piezoelectric body is set to be larger than the thickness of the first piezoelectric body. As a result, the distance from the electrode located closest to the constraining layer in the active layer to the first relay electrode and the second relay electrode is increased. Therefore, when a voltage is applied between the individual electrode and the common electrode, the common It becomes difficult to be affected by the electric field generated between the electrode and the first relay electrode or the electric field generated between the individual electrode and the second relay electrode, and the displacement of the constraining layer is suppressed. Furthermore, since the first relay electrode and the second relay electrode provided in the constraining layer are not floating electrodes, it is possible to prevent the constraining layer from being displaced due to charge accumulation due to static electricity. As described above, it is possible to reliably prevent the crosstalk between the piezoelectric active portions corresponding to the adjacent individual electrodes and the deformation of the active layer on the side opposite to the displacement transmission surface (constraint layer side) of the element.

  Preferably, the first relay electrode and the second relay electrode are provided so as to avoid a region where the individual electrode and the common electrode overlap. A region where the individual electrode and the common electrode overlap in the piezoelectric element includes a piezoelectric active portion (a portion where displacement actually occurs) of the active layer. Therefore, by providing the first relay electrode and the second relay electrode so as to avoid the region where the individual electrode and the common electrode overlap, between the common electrode and the first relay electrode or between the individual electrode and the second relay electrode. Even if an electric field is generated and a minute displacement occurs in the constraining layer, the influence on the piezoelectric active portion is small. As a result, crosstalk between piezoelectric active portions corresponding to adjacent individual electrodes and deformation of the active layer with respect to the constraining layer side can be prevented more reliably.

  Preferably, a common electrode is provided in a solid shape at a position closest to the constraining layer in the active layer and a position opposite to the constraining layer in the active layer. In this case, when the active layer and the constraining layer are integrally baked, it is possible to reduce warping or undulation deformation of the element due to the baking.

  According to the present invention, it is possible to reliably prevent crosstalk between adjacent individual electrodes in the active layer and deformation of the piezoelectric element to the side opposite to the displacement transmission surface of the piezoelectric element. As a result, the amount of displacement of the active layer relative to the displacement transmission surface side of the piezoelectric element can be increased.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a piezoelectric element according to the invention will be described in detail with reference to the drawings.

  FIG. 1 is an exploded perspective view showing an embodiment of a piezoelectric element according to the present invention, and FIG. 2 is a partial side sectional view of the piezoelectric element. In each figure, the piezoelectric element 1 of the present embodiment is a laminated piezoelectric element having a rectangular parallelepiped shape. The laminated piezoelectric element 1 includes an active layer 2, a displacement transmission layer 3 laminated on the active layer 2, and a constraining layer 4 laminated on the opposite side of the displacement transmission layer 3 with respect to the active layer 2. I have.

  The active layer 2 has a piezoelectric body 5 and a plurality of internal individual electrodes 6 and internal common electrodes 7 that face each other with the piezoelectric body 5 interposed therebetween. These internal individual electrodes 6 and internal common electrodes 7 are alternately stacked over a plurality of layers with the piezoelectric bodies 5 interposed therebetween. An internal common electrode 7 is provided at a position closest to the displacement transmitting layer 3 (lower side) of the active layer 2 and a position closest to the constraining layer 4 side (upper side) of the active layer 2. The internal individual electrodes 6 of each layer are arranged in a two-dimensional matrix. The active layer 2 is a layer in which the piezoelectric body 5 expands and contracts (displaces) in the stacking direction when a voltage is applied between the internal individual electrode 6 and the internal common electrode 7.

  The piezoelectric body 5 is made of, for example, a piezoelectric ceramic material mainly composed of PZT (lead zirconate titanate). The internal individual electrode 6 and the internal common electrode 7 are made of, for example, Ag and Pd.

  Even if a voltage is applied between the internal individual electrode 6 and the internal common electrode 7, the displacement transmission layer 3 does not displace itself and transmits the displacement of the active layer 2 to a driving object (not shown). Is a layer. The driving object is disposed adjacent to the displacement transmission layer 3. The displacement transmission layer 3 is formed of the same piezoelectric body 5 as the active layer 2.

  The constraining layer 4 includes a plurality (two layers in this case) of piezoelectric bodies 8 stacked on each other, and a plurality of individual relay electrodes 9 and a common relay electrode 10 disposed between the piezoelectric bodies 8 of each layer. . A plurality of individual terminal electrodes 11 for applying a voltage to each internal individual electrode 6 and a common terminal electrode 12 for applying a voltage to the internal common electrode 7 are provided on the upper surface of the constraining layer 4. The constraining layer 4 is a layer that regulates the displacement of the active layer 2 to the opposite side, that is, to the upper side of the displacement transmission layer 3 when a voltage is applied between the internal individual electrode 6 and the internal common electrode 7.

  The piezoelectric body 8 is made of the same ceramic material as the piezoelectric body 5 of the active layer 2. The individual relay electrode 9 and the common relay electrode 10 are formed of, for example, Ag and Pd, similarly to the internal individual electrode 6 and the internal common electrode 7. The individual terminal electrode 11 and the common terminal electrode 12 are made of, for example, one of Ag, Au, Cu, or an alloy thereof.

  In such a laminated piezoelectric element 1, the total thickness of the constraining layer 4 may be 1/3 or more, preferably 1/2 or more of the total thickness of the active layer 2. The thickness per layer of each piezoelectric body 5 constituting the active layer 2 is, for example, about 15 to 50 μm. The thickness of each piezoelectric body 8 constituting the constraining layer 4 is larger than the thickness of the piezoelectric body 5.

  Specifically, the multilayer piezoelectric element 1 includes piezoelectric bodies 5A and 5B in which a plurality of internal individual electrodes 6 are formed, piezoelectric bodies 5C and 5D in which an internal common electrode 7 is formed, and a plurality of individual relay electrodes 9. And a piezoelectric body 8A in which the common relay electrode 10 is formed, and a piezoelectric body 8B in which the plurality of individual terminal electrodes 11 and the common terminal electrode 12 are formed. The multilayer piezoelectric element 1 has a structure in which a piezoelectric body 8B, a piezoelectric body 8A, a piezoelectric body 5C, a piezoelectric body 5A, a piezoelectric body 5C, a piezoelectric body 5A, a piezoelectric body 5C, a piezoelectric body 5B, and a piezoelectric body 5D are stacked in order from the top. There is no.

  As shown in FIG. 3, the plurality of internal individual electrodes 6 and the internal common relay electrode 13 are formed on the upper surface of the piezoelectric body 5 </ b> A. The internal common relay electrode 13 is disposed at one end of the upper surface of the piezoelectric body 5A. The piezoelectric body 5 </ b> A is formed with a plurality of through holes 14 electrically connected to the internal individual electrodes 6 and through holes 15 electrically connected to the internal common relay electrode 13. The through holes 14 and 15 are filled with a conductive material made of, for example, Ag and Pd.

  As shown in FIG. 4, a plurality of internal individual electrodes 6 and internal common relay electrodes 13 are formed on the upper surface of the piezoelectric body 5B, as with the piezoelectric body 5A. The through hole 15 is formed in the piezoelectric body 5B similarly to the piezoelectric body 5A, but the through hole 14 is not formed.

  As shown in FIG. 5, the internal common electrode 7 and a plurality of internal individual relay electrodes 16 are formed on the upper surface of the piezoelectric body 5C. The internal common electrode 7 is formed in a solid shape in a region excluding both side edges on the upper surface of the piezoelectric body 5C. The plurality of internal individual relay electrodes 16 are formed so as to sandwich the internal common electrode 7 between both side edges of the upper surface of the piezoelectric body 5C. The piezoelectric body 5 </ b> C has through holes 17 electrically connected to the internal common electrode 7 and a plurality of through holes 18 electrically connected to the internal individual relay electrodes 16. The through holes 17 and 18 are filled with a conductive material.

  As shown in FIG. 6, an internal common electrode 7 is formed on the upper surface of the piezoelectric body 5D in the same manner as the piezoelectric body 5C. The piezoelectric body 5D is not provided with the internal individual relay electrode 16 and the through holes 17 and 18 formed in the piezoelectric body 5C. The internal common electrode 7 may be formed in a solid shape on the entire upper surface of the piezoelectric body 5D.

  As shown in FIG. 7, the plurality of individual relay electrodes 9 and the common relay electrode 10 are formed on the upper surface of the piezoelectric body 8A. The individual relay electrode 9 is formed at a position corresponding to the internal individual relay electrode 16. The common relay electrode 10 is formed at a position corresponding to the internal common relay electrode 13. Therefore, the individual relay electrode 9 and the common relay electrode 10 are provided so as to avoid a region where the internal individual electrode 6 and the internal common electrode 7 overlap with each other in the stacking direction (a region in which the piezoelectric body 5 is distorted by the piezoelectric effect). It will be that. The piezoelectric body 8 </ b> A is formed with a plurality of through holes 19 electrically connected to the individual relay electrodes 9 and through holes 20 electrically connected to the common relay electrodes 10. The through holes 19 and 20 are filled with a conductive material.

  As shown in FIG. 8, the plurality of individual terminal electrodes 11 and the common terminal electrode 12 are formed on the upper surface of the piezoelectric body 8B. The individual terminal electrode 11 is formed at a position corresponding to the individual relay electrode 9. The common terminal electrode 12 is formed at a position corresponding to the common relay electrode 10. In addition, a plurality of through holes 21 electrically connected to the individual terminal electrodes 11 and through holes 22 electrically connected to the common terminal electrodes 12 are formed in the piezoelectric body 8B. The through holes 21 and 22 are filled with a conductive material.

  In the multilayer piezoelectric element 1 configured as described above, the individual terminal electrode 11 is connected to the individual internal electrode of each layer through the through hole 21, the individual relay electrode 9, the through hole 19, the internal individual relay electrode 16, and the through holes 18 and 14. The electrode 6 is electrically connected. The common terminal electrode 12 is electrically connected to the internal common electrode 7 of each layer through the through hole 22, the common relay electrode 10, the through holes 20 and 17, the internal common relay electrode 13 and the through hole 15. Here, in order to ensure electrical connection between the through holes 19 and 21 via the individual relay electrodes 9, it is desirable to dispose the through holes 19 and 21 as shown in FIG. The same applies to the through holes 20 and 22, the through holes 18 and 19, the through holes 14 and 18, the through holes 17 and 20, and the through holes 15 and 17.

  Next, a procedure for manufacturing the multilayer piezoelectric element 1 described above will be described. First, for example, a piezoelectric ceramic mainly composed of PZT is prepared, and a paste in which an organic binder, an organic solvent, or the like is mixed is prepared. And the ceramic green sheet used as said piezoelectric material 5 and 8 is formed by carrying out sheet shaping | molding of a paste by using PET film as a carrier film.

  Subsequently, for example, a through hole is formed in the green sheet by irradiating a predetermined position of the green sheet with a third harmonic laser beam of YAG, for example. At this time, the through hole is processed so that the hole diameter becomes, for example, 40 to 50 μm after firing described later. Then, for example, a conductive paste in which a conductive material configured with a ratio of Ag: Pd = 7: 3 and an organic binder / organic solvent is mixed is prepared, and the through paste is filled into the through holes by a screen printing method or the like. Note that it is not necessary to provide a through hole in the green sheet forming the lowermost piezoelectric body 5 (displacement transmission layer 3).

  Subsequently, using the same conductive paste as the through-hole filler, for example, an internal electrode pattern to be the internal individual electrode 6 and the internal common electrode 7 is formed in a predetermined region on the surface of the green sheet by a screen printing method or the like. .

  Subsequently, various green sheets on which the internal electrode patterns are printed are stacked in a predetermined order by a predetermined number of sheets, and further, green sheets on which the internal electrode patterns are not printed are stacked on the green sheets. A green laminate having the layer 2, the displacement transmission layer 3 and the constraining layer 4 is formed. Then, the green laminate is pressed at a pressure of about 100 MPa while applying heat of about 60 ° C., for example, and the green sheets of the respective layers are pressure-bonded. Thereafter, the green laminate is cut into a predetermined dimension.

  Subsequently, the green laminate is placed on a setter, and degreasing (debinding) of the green laminate is performed at a temperature of about 400 ° C., for example. Thereafter, the setter on which the green laminate is placed is placed in a closed mortar, and the green laminate is fired at a temperature of, for example, about 1100 ° C. for about 2 hours to obtain a sintered body. At this time, since the internal common electrode 7 is formed as a solid pattern on the uppermost layer and the lowermost layer of the active layer 2 as described above, warpage, undulation, deformation, etc. of the green laminated body caused by firing are reduced. can do.

  Subsequently, the individual terminal electrode 11 and the common terminal electrode 12 made of, for example, Ag are formed on the upper surface of the fired element. As a method for forming the terminal electrodes 11 and 12, baking, sputtering, vapor deposition, electroless plating, or the like is used.

  Finally, lead wires such as FPC (flexible printed wiring board) are attached to the terminal electrodes 11 and 12 by soldering or the like. Then, for example, in an environment of a temperature of 120 ° C., the polarization process is performed by applying a voltage, for example, for 3 minutes so that the electric field strength with respect to the thickness of the piezoelectric body 5 becomes 3 kV / mm. Thereby, the multilayer piezoelectric element 1 as a piezoelectric ceramic actuator is completed.

  In the multilayer piezoelectric element 1 as described above, when a predetermined voltage is applied between any individual terminal electrode 11 and the common terminal electrode 12, the internal individual electrode 6 and the internal common electrode corresponding to the individual terminal electrode 11 are applied. A voltage is applied between the two. As a result, an electric field is generated in a portion (piezoelectric active portion) sandwiched between the internal individual electrode 6 and the internal common electrode 7 in the piezoelectric body 5 of each layer constituting the active layer 2, and the active layer 2 is displaced in the stacking direction. It becomes like this. Then, the displacement of the active layer 2 is transmitted to a driving object (not shown) via the displacement transmission layer 3, and the driving object is controlled.

  At this time, the constraining layer 4 is provided with a plurality of individual relay electrodes 9, but when a voltage is applied between the individual terminal electrode 11 and the common terminal electrode 12, the voltage is also applied to the corresponding individual relay electrode 9. Therefore, an electric field is also generated between the uppermost internal common electrode 7 in the constraining layer 4 and the individual relay electrode 9. For this reason, if the distance between the uppermost internal common electrode 7 and the individual relay electrode 9 is short because the piezoelectric body 8 constituting the constraining layer 4 is thin, the piezoelectric body 8 is connected to the internal common electrode 7 and the individual relay electrode 9. Since the electric field strength of the sandwiched portion increases, the constraining layer 4 is displaced.

  Accordingly, although the constraining layer 4 is present on the active layer 2, the active layer 2 is displaced (deformed) upward in accordance with the displacement of the constraining layer 4, or the piezoelectric active portion corresponding to a certain internal individual electrode 6 is A so-called crosstalk that causes the displacement of the piezoelectric active portion corresponding to the adjacent internal individual electrode 6 occurs, and as a result, the displacement of the active layer 2 toward the displacement transmission layer 3 is inhibited. Such a problem occurs remarkably when the internal individual electrodes 6 are arranged at a high density.

  On the other hand, in the present embodiment, the thickness of the piezoelectric body 8 constituting the constraining layer 4 is larger than the thickness of the piezoelectric body 5 constituting the active layer 2, so that the uppermost internal common electrode 7 and the individual relay electrode 9 is separated from the distance. For this reason, since the electric field strength of the portion sandwiched between the internal common electrode 7 and the individual relay electrode 9 in the piezoelectric body 8 is reduced, the displacement amount of the constraining layer 4 is reduced.

  Here, in order to sufficiently reduce the amount of displacement of the constraining layer 4 without increasing the height of the multilayer piezoelectric element 1 more than necessary, the thickness of the piezoelectric body 8 constituting the constraining layer 4 is set to an active layer. It is preferably 1.3 to 5.0 times, and particularly preferably 1.5 to 3.0 times that of the thinnest piezoelectric body 5 among the plurality of layers of piezoelectric bodies 5 constituting 2.

  Further, since the individual relay electrode 9 is provided at a position that avoids a region where the internal individual electrode 6 and the internal common electrode 7 overlap, the individual relay electrode 9 is sandwiched between the uppermost internal common electrode 7 and the individual relay electrode 9. The electric field generated in the portion has little influence on the displacement of the piezoelectric active portion of the active layer 2. Furthermore, since the constraining layer 4 is not provided with a floating electrode to which no voltage is applied, the constraining layer 4 is not displaced by charge accumulation due to static electricity.

  As a result, even when a plurality of internal individual electrodes 6 are arranged in the active layer 2 at a high density, crosstalk between piezoelectric active portions corresponding to adjacent internal individual electrodes 6, The deformation of the active layer 2 can be suppressed. As a result, the amount of displacement of the active layer 2 toward the lower side of the element (drive object side) can be increased, and control with little variation can be performed on the drive object corresponding to each internal individual electrode 6. . Accordingly, it is possible to realize miniaturization and high integration of the high-quality multilayer piezoelectric element 1.

  In the stacked piezoelectric element including the active layer, the displacement transmission layer, and the constraining layer as described above, the thickness of the first piezoelectric body constituting the active layer and the displacement transmission layer is fixed to 25 μm, and the constraining layer is configured. The thickness of the second piezoelectric body was changed, and the effect of crosstalk between piezoelectric active portions corresponding to adjacent internal individual electrodes was verified.

  Here, 300 internal individual electrodes were provided per layer, and these internal individual electrodes were arranged in a two-dimensional matrix (75 rows × 4 columns) in the element. In each internal individual electrode, the length of the region (active area) overlapping with the internal common electrode in the stacking direction was 1.5 mm and the width was 150 μm. The distance between the active areas adjacent in the row direction was 250 μm, and the distance between the active areas adjacent in the column direction was 1 mm. The driving electric field strength for examining the influence of crosstalk was 1 kV per 1 mm thickness of the active layer.

  When the thickness of the second piezoelectric body constituting the constraining layer is set to 25 μm, which is the same as the thickness of the first piezoelectric body constituting the active layer, and the total thickness of the constraining layer is 1/3 of the total thickness of the active layer. The effect of improving crosstalk was not obtained.

  However, when the thickness of only one second piezoelectric body adjacent to the active layer among the plurality of second piezoelectric bodies is made 1.3 times the thickness of the first piezoelectric body, the crosstalk can be sufficiently improved. was gotten. The effect of crosstalk is eliminated when the thickness of only one second piezoelectric material adjacent to the active layer is 1.5 times or more the thickness of the first piezoelectric material (the total thickness of the constraining layer at this time). Was 1/2) of the total thickness of the active layer.

  The piezoelectric element according to the present invention is not limited to the above embodiment. For example, in the above embodiment, the thicknesses of the piezoelectric bodies 8 of all the layers constituting the constraining layer 4 are larger than the thickness of the piezoelectric bodies 5 constituting the active layer 2, but at least one layer adjacent to the active layer 2 The thickness of the piezoelectric body 8 may be made larger than the thickness of the piezoelectric body 5.

  Moreover, in the said embodiment, although it was set as the structure which laminated | stacked the several piezoelectric material 5 which comprises the active layer 2, if the especially big displacement amount is not required, the piezoelectric material 5 may be only one layer.

  Furthermore, in the above embodiment, the internal common electrode 7 is formed in a solid shape on the surface of the piezoelectric body 5, but the pattern shape of the internal common electrode 7 is not particularly limited to a solid shape, for example, a plurality of internal individual electrodes. A plurality of electrode pattern portions having a shape corresponding to the electrode 6 may be included. Further, the internal electrodes positioned in the uppermost layer and the lowermost layer of the active layer 2 are not limited to the internal common electrode 7 as in the above embodiment, but may be the internal individual electrode 6.

  Moreover, in the said embodiment, although it was set as the structure which arrange | positions the displacement transmission layer 3 in the drive target object side of the active layer 2, such a displacement transmission layer 3 does not necessarily need to provide.

It is a disassembled perspective view which shows one Embodiment of the piezoelectric element concerning this invention. It is a partial sectional side view of the piezoelectric element shown in FIG. It is a top view of the piezoelectric material in which the internal individual electrode shown in FIG. 1 was formed. It is a top view of the other piezoelectric material in which the internal individual electrode shown in FIG. 1 was formed. It is a top view of the piezoelectric material in which the internal common electrode shown in FIG. 1 was formed. It is a top view of the other piezoelectric material in which the internal common electrode shown in FIG. 1 was formed. It is a top view of the piezoelectric material in which the relay electrode shown in FIG. 1 was formed. It is a top view of the piezoelectric material in which the terminal electrode shown in FIG. 1 was formed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Stacking type piezoelectric element, 2 ... Active layer, 4 ... Constraining layer, 5, 5A-5D ... Piezoelectric body (1st piezoelectric body), 6 ... Internal individual electrode, 7 ... Internal common electrode, 8, 8A, 8B ... Piezoelectric body (second piezoelectric body), 9 ... individual relay electrode (first relay electrode), 10 ... common relay electrode (second relay electrode), 11 ... individual terminal electrode (first terminal electrode), 12 ... common terminal electrode (Second terminal electrode), 19 ... through hole (first through hole), 20 ... through hole (second through hole), 21 ... through hole (first through hole), 22 ... through hole (second through hole) .

Claims (3)

An active layer having a plurality of individual electrodes and a common electrode facing each other across the first piezoelectric body, and being displaced by applying a voltage between the individual electrode and the common electrode;
A constraining layer that is laminated to the active layer and restricts displacement of the active layer relative to one side of the active layer;
A plurality of first terminal electrodes for applying a voltage to each of the individual electrodes and a second terminal electrode for applying a voltage to the common electrode, provided on a surface of the constraining layer opposite to the active layer; With
The constraining layer is disposed between the plurality of second piezoelectric bodies stacked on each other and the second piezoelectric bodies, and the individual electrodes are connected to the individual electrodes via first through holes formed in the second piezoelectric bodies. The plurality of first relay electrodes for electrically connecting the first terminal electrodes and the second piezoelectric bodies are disposed between the second piezoelectric bodies and the second through holes formed in the second piezoelectric bodies. A second relay electrode for electrically connecting the common electrode and the second terminal electrode,
The piezoelectric element according to claim 1, wherein a thickness of the second piezoelectric body adjacent to the active layer is larger than a thickness of the first piezoelectric body.   2. The piezoelectric element according to claim 1, wherein the first relay electrode and the second relay electrode are provided so as to avoid a region where the individual electrode and the common electrode overlap each other. 3. The solid electrode is provided in a solid shape at a position closest to the constraining layer in the active layer and at a position opposite to the constraining layer in the active layer. The piezoelectric element as described.

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