JP2018129731A - Vibration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration device in which improvement of a displacement amount is achieved.SOLUTION: A vibration device 1 includes a piezoelectric element 10 having a piezoelectric element 11 having first and second main surfaces 11a and 11b opposed to each other and first and second electrodes 12 and 13 disposed on the first main surface 11a, an insulating resin member 20 having a third main surface 20a joined to the piezoelectric element 10 and a fourth main surface 20b opposing the third main surface 20a, a vibrating member 30 made of metal, which has a fifth main surface 30a joined to the fourth main surface 20b of the resin member 20 and a sixth main surface 30b opposing the fifth main surface 30a, third and fourth electrodes 25 disposed on the third main surface 20a of the resin member 20, a first conductive resin layer 27 connecting the first electrode 12 and the third electrode 25, and a second conductive resin layer connecting the second electrode 13 and the fourth electrode.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vibrating device.

  There is known a vibration device that includes a piezoelectric element and a vibration member having a pair of main surfaces facing each other, and the piezoelectric element and the main surface of the vibration member are joined to each other (for example, Patent Document 1 and Patent Document 2).

JP 04-70100 A

  In the vibration device described in Patent Document 1, the vibration member is a glass plate. For this reason, the Q value and strength of the vibration member are relatively low, and it is difficult to improve the displacement.

  An object of the present invention is to provide a vibration device in which the amount of displacement is improved.

  A vibrating device according to the present invention includes a piezoelectric element having first and second main surfaces facing each other, a first and second electrodes arranged on the first main surface, and a piezoelectric element. An insulating resin member having a third main surface bonded to the element and a fourth main surface facing the third main surface; a fifth main surface bonded to the fourth main surface of the resin member; A vibration member made of metal, a third and a fourth electrode disposed on the third main surface of the resin member, a first electrode and a third electrode, having a sixth main surface opposite to the fifth main surface And a second conductive resin layer connecting the second electrode and the fourth electrode.

  In the vibration device according to the present invention, the vibration member is made of metal. A vibrating member made of metal has a higher Q value and strength than a vibrating member made of glass. For this reason, the displacement amount of the vibration device is improved. An insulating resin member is disposed in a region sandwiched between the vibration member and the piezoelectric element. Therefore, even when a metal is used for the vibration member instead of glass, a short circuit is prevented between the vibration member and the piezoelectric element. The first and second electrodes and the third and fourth electrodes of the piezoelectric element are connected by the first and second conductive resin layers. For this reason, the displacement amount of the vibration device is improved as compared with the case where the electrodes are in contact with each other.

  The third and fourth electrodes may be separated from the piezoelectric element when viewed from the direction orthogonal to the first main surface. When the third and fourth electrodes are arranged in a region sandwiched between the piezoelectric element and the resin member, the piezoelectric element comes into contact with the third and fourth electrodes, and is on the fifth and sixth main surfaces of the vibration member. There is a risk of tilting. When the piezoelectric element is pressure-bonded to the resin member, a force may be applied to the piezoelectric element from the third and fourth electrodes, and the piezoelectric element body may be cracked. If the third and fourth electrodes are separated from the piezoelectric element when viewed from the direction orthogonal to the first main surface, the inclination of the piezoelectric element and the cracking of the piezoelectric element body can be suppressed.

  An insulating adhesive layer that joins the second main surface of the piezoelectric element and the third main surface of the resin member is further provided, and the piezoelectric element is electrically connected to the first electrode on the second main surface. There may be five electrodes, and the adhesive layer may cover the fifth electrode. In this case, a short circuit between the fourth electrode and the second conductive resin layer and the fifth electrode is prevented.

  According to the present invention, it is possible to provide a vibration device in which the amount of displacement is improved.

It is a top view of a vibration device concerning one embodiment. It is a figure for demonstrating the cross-sectional structure of a vibration device. It is a top view of the vibration device which concerns on the modification of this embodiment.

  Hereinafter, 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, with reference to FIG.1 and FIG.2, the structure of the vibration device which concerns on this embodiment is demonstrated. FIG. 1 is a plan view of a vibrating device 1 according to the present embodiment. FIG. 2 is a cross-sectional view of the vibration device 1 cut along a plane parallel to the long side of the vibration device 1.

  As shown in FIG. 1, the vibration device 1 includes a piezoelectric element 10, a resin member 20, a vibration member 30, an adhesive layer 40 that joins the piezoelectric element 10 and the resin member 20, and a resin member 20. An adhesive layer 50 that joins the vibration member 30 is provided. The piezoelectric element 10 includes a piezoelectric element body 11, a pair of electrodes 12 and 13, an electrode 14, and a via conductor 19.

  The piezoelectric element body 11 has a plate shape. In the present embodiment, the piezoelectric element body 11 has a rectangular parallelepiped shape. The rectangular parallelepiped shape includes a rectangular parallelepiped shape in which corners and ridges are chamfered, and a rectangular parallelepiped shape in which corners and ridges are rounded. The piezoelectric element body 11 has a main surface 11a and a main surface 11b facing each other. The dimensions of the main surfaces 11a and 11b of the piezoelectric element 11, that is, the dimensions of the piezoelectric element 10 when viewed from the direction orthogonal to the main surfaces 11a and 11b are, for example, 30 mm × 30 mm. The shape of the piezoelectric element 11 is not limited to a rectangular parallelepiped shape, and may be, for example, a disk shape. In the direction orthogonal to the main surface 11a, for example, the thickness of the piezoelectric element 10 is 100 μm, the thickness of the piezoelectric element 11 is 70 μm, and the thickness of each of the electrodes 12, 13, and 14 is 15 μm.

The piezoelectric element body 11 is made of a piezoelectric ceramic material. Examples of the piezoelectric ceramic material include PZT [Pb (Zr, Ti) O ₃ ], PT (PbTiO ₃ ), PLZT [(Pb, La) (Zr, Ti) O ₃ ], or barium titanate (BaTiO ₃ ). Can be mentioned. The piezoelectric element body 11 is composed of, for example, a sintered body of a ceramic green sheet containing the above-described piezoelectric ceramic material.

  As shown in FIG. 2, a pair of electrodes 12 and 13 are disposed on the main surface 11 a of the piezoelectric element body 11. An electrode 14 is disposed on the main surface 11 b of the piezoelectric element body 11. The electrodes 12, 13, and 14 are conductors including a conductive material (for example, Ag, Pd, or Cu). These conductors are configured as a sintered body of a conductive paste containing a conductive material.

  The electrode 12 and the electrode 13 are separated from each other on the main surface 11a. The area where the electrode 13 is in contact with the main surface 11a is larger than the area where the electrode 12 is in contact with the main surface 11a. The area where the electrode 14 is in contact with the main surface 11b is larger than the area where the electrode 12 is in contact with the main surface 11a or the area where the electrode 13 is in contact with the main surface 11a. The electrode 13 and the electrode 14 have regions that overlap each other when viewed from the direction orthogonal to the main surface 11a.

  The via conductor 19 physically and electrically connects the electrode 12 and the electrode 14. The via conductor 19 is disposed in the vicinity of the side surface of the piezoelectric element 10 when viewed from the direction orthogonal to the main surface 11a, and penetrates from the main surface 11a to the main surface 11b. The via conductor 19 is a conductor made of a conductive material (for example, Ag, Pd, or Cu), like the electrodes 12, 13, and 14.

  The resin member 20 has a main surface 20 a and a main surface 20 b facing each other parallel to the main surfaces 11 a and 11 b of the piezoelectric element body 11. The resin member 20 has a film shape or a plate shape, and has a rectangular shape when viewed from a direction orthogonal to the main surface 20a. The rectangular shape includes, for example, a shape with rounded corners. The shape of the resin member 20 is not limited to a rectangular shape, and may be, for example, a circular shape.

  The resin member 20 is made of polyimide resin, PET resin, polyparaxylylene resin, or the like, and has insulating properties. The area of the resin member 20 is larger than the area of the piezoelectric element 10 when viewed from the direction orthogonal to the main surface 20a. For example, the dimensions of the main surfaces 20a and 20b of the resin member 20 are 40 mm × 40 mm. In the direction orthogonal to the main surface 20 a, the thickness of the resin member 20 is smaller than the thickness of the piezoelectric element 10. For example, the thickness of the resin member 20 in the direction orthogonal to the main surface 20a is 25 μm. The thermal expansion coefficient of the resin member 20 is larger than the thermal expansion coefficient of the piezoelectric element 10.

  An extension portion 21 is connected to the end portion of the resin member 20. In the present embodiment, the extending portion 21 extends linearly from one side of the outer edge of the resin member 20 in a direction parallel to the main surface 20 a and beyond the edge of the vibration member 30. The extension 21 is joined to the vibration member 30 in the same manner as the resin member 20 in a region overlapping the vibration member 30 when viewed from the direction orthogonal to the main surface 20a.

  The width of the extension part 21 is shorter than the length of the side of the resin member 20 to which the extension part 21 is connected, for example, 12 mm. In the present embodiment, the extending portion 21 is made of the same material as the resin member 20. The thickness of the extending portion 21 is the same as that of the resin member 20 at least in the region overlapping the vibration member 30 when viewed from the direction orthogonal to the main surface 20 a, and is smaller than the thickness of the piezoelectric element 10. The thermal expansion coefficient of the extending portion 21 is also larger than the thermal expansion coefficient of the piezoelectric element 10.

  A pair of electrodes 25 and 26 that are electrically connected to the piezoelectric element 10 are provided on the extension portion 21 and the main surface 20 a of the resin member 20. The electrodes 25 and 26 have end portions in the vicinity of the edge of the resin member 20 and are separated from the piezoelectric element 10 when viewed from a direction orthogonal to the main surface 20a. The electrodes 25 and 26 extend from the vicinity of the edge of the resin member 20 in a direction parallel to the main surface 20a. The electrodes 25 and 26 are connected to a power source (not shown) by end portions (not shown) provided on the extending portion 21. The electrodes 25 and 26 are configured as a sintered body of a conductive paste containing a conductive material (for example, Ag, Pd, or Cu).

  The electrode 25 is electrically connected to the electrode 12 positioned on the main surface 11 a of the piezoelectric element 10 in the resin member 20 by the conductive resin layer 27. The electrode 26 is electrically connected to the electrode 13 arranged on the main surface 11 a of the piezoelectric element 10 in the resin member 20 by the conductive resin layer 28. The conductive resin layers 27 and 28 are made of a synthetic resin (for example, an epoxy resin, a urethane resin, or an imide resin) and a conductive filler (such as a substance subjected to Ag, Cu, or Ag plating).

  The vibration member 30 has a main surface 30a and a main surface 30b facing each other parallel to the main surfaces 20a and 20b. The vibration member 30 has a plate shape, and has a rectangular shape when viewed from a direction orthogonal to the main surface 30a. The rectangular shape includes, for example, a shape with rounded corners. The extension portion 21 described above is drawn from the short side of the vibration member 30. The shape of the vibration member 30 is not limited to a rectangular shape, and may be a circular shape or the like. In the present embodiment, when viewed from the direction orthogonal to the main surface 30 a, the piezoelectric element 10 includes the vibrating member 30 such that each side of the outer edge of the vibrating member 30 is parallel to each side of the outer edge of the piezoelectric element 10. It is arranged near the center.

  The area of the vibrating member 30 is larger than the area of the piezoelectric element 10 and the area of the resin member 20 when viewed from the direction orthogonal to the main surface 20a. For example, the dimensions of the main surfaces 30a and 30b of the vibration member 30 are 80 m × 60 mm. In the direction orthogonal to the main surface 20 a, the thickness of the resin member 20 is smaller than the thickness of the vibration member 30. In the direction orthogonal to the main surface 20a, the thickness of the vibration member 30 is greater than or equal to the thickness of the piezoelectric element 10. For example, the thickness of the vibrating member 30 in the direction orthogonal to the main surface 20a is 250 μm. The thermal expansion coefficient of the vibration member 30 is larger than the thermal expansion coefficients of the piezoelectric element 10 and the resin member 20. The vibration member 30 is made of a metal made of Ni, stainless steel, brass, or invar.

  As shown in FIG. 2, the resin member 20 is separated from the end of the vibration member 30 by Gap (a) and viewed from the end of the piezoelectric element 10 as viewed from the direction orthogonal to the main surface 20a. Is located just away. In the short side direction of the vibrating member 30, Gap (a) is 2% or more of the length of the short side of the vibrating member 30, and Gap (b) is the length of the side of the piezoelectric element 10 parallel to the short side of the vibrating member 30. 2% or more of the length. In the long side direction of the vibration member 30, Gap (a) is 2% or more of the length of the long side of the vibration member 30, and Gap (b) is the length of the side of the piezoelectric element 10 parallel to the long side of the vibration member 30. 2% or more of the length.

  That is, when the dimensions of the main surfaces 30 a and 30 b of the vibration member 30 are 80 mm × 60 mm, the end portion of the resin member 20 is located 2 mm or more away from the long side of the vibration member 30 and from the short side of the vibration member 30. It is located at a distance of 2 mm or more. When the dimension of the piezoelectric element 10 when viewed from the direction orthogonal to the main surface 11a is 30 mm × 30 mm, the end of the resin member 20 is located at least 0.5 mm away from the long side of the piezoelectric element 10, It is located at least 0.5 mm away from the short side of the element 10.

  For example, the dimensions of the main surfaces 20a and 20b of the resin member 20 shown in FIG. 2 are 32 mm × 32 mm. Gap (a) is 14 mm and Gap (b) is 24 mm. The dimensions of the main surfaces 20a and 20b of the resin member 20 shown in FIG. 3 are 76 mm × 56 mm. Gap (a) is 2 mm and Gap (b) is 2 mm. FIG. 3 is a plan view of the vibration device 1 according to a modification of the present embodiment.

  The adhesive layer 40 has an insulating property, and joins the piezoelectric element 10 and the main surface 20a of the resin member 20. In the present embodiment, the adhesive layer 40 is attached not only to the main surface 11 b side of the piezoelectric element 10 but also to the side surface. The adhesive layer 40 covers the electrode 14 disposed on the main surface 11 b of the piezoelectric element 10. That is, the electrode 14 is surrounded by the adhesive layer 40 and the piezoelectric element body 11 and is not exposed. The thickness of the adhesive layer 40 is, for example, 7 μm or less.

  The adhesive layer 50 has an insulating property, and joins the main surface 20 b of the resin member 20 and the main surface 30 a of the vibration member 30. The extending portion 21 is joined to the vibration member 30 by the adhesive layer 50 in a region overlapping the vibration member 30 when viewed from the direction orthogonal to the main surface 20a. The thickness of the adhesive layer 50 is, for example, 7 μm or less.

  The adhesion area where the adhesive layer 50 adheres to the vibration member 30 is larger than the adhesion area where the adhesive layer 40 adheres to the resin member 20. In the present embodiment, the adhesive layer 40 is bonded to the entire main surface 11 b side of the piezoelectric element 10, and the adhesive layer 50 is bonded to the entire main surface 20 b of the resin member 20.

  For the adhesive layers 40 and 50, resin, double-sided tape or the like is used. For example, an epoxy resin, a urethane resin, a cyanoacrylate resin, an anaerobic curable acrylic resin, or the like is used. In particular, the use of an anaerobic curable acrylic resin prevents the resin member 20 from being deformed by heat. When an epoxy resin, a urethane resin, or a cyanoacrylate resin is used, the adhesive layers 40 and 50 are cured at a low temperature, so that deformation of the resin member 20 due to heat is suppressed. The adhesive layers 40 and 50 do not contain a conductive filler.

  Next, the operation and effect of the vibration device 1 will be described.

  When voltages having different polarities are applied to the electrode 12 and the electrode 13, an electric field is generated between the electrode 14 and the electrode 13 that are electrically connected to the electrode 12. Therefore, in the piezoelectric element 11, the region sandwiched between the electrode 13 and the electrode 14 becomes the active region, and displacement occurs in the active region. That is, when an AC voltage is applied to the pair of electrodes 12 and 13, the piezoelectric element 10 repeatedly expands and contracts according to the frequency of the applied AC voltage.

  The piezoelectric element 10 and the resin member 20 are joined by an adhesive layer 40. The resin member 20 and the vibration member 30 are joined by an adhesive layer 50. For this reason, the vibration member 30 flexes and vibrates integrally with the piezoelectric element 10 according to repeated expansion and contraction in the piezoelectric element 10. At this time, the higher the Q value and strength of the vibration member 30, the more the displacement amount of the vibration member 30 is improved.

  In the vibration device 1, the vibration member 30 is made of metal. The vibration member 30 made of metal has a higher Q value and strength than a vibration member made of glass. For this reason, in the vibration device 1, the amount of displacement is improved.

  An insulating resin member 20 is disposed in a region sandwiched between the vibration member 30 and the piezoelectric element 10. For this reason, even when a metal is used for the vibrating member 30 instead of glass, a short circuit is prevented between the vibrating member 30 and the piezoelectric element 10. Since the electrodes 25 and 26 are disposed on the insulating resin member 20, a short circuit is prevented between the electrodes 25 and 26 and the vibration member 30.

  The electrodes 12 and 13 and the electrodes 25 and 26 of the piezoelectric element 10 are connected by conductive resin layers 27 and 28. For this reason, the displacement amount of the vibration device 1 improves compared with the case where electrodes contact.

  The electrodes 25 and 26 are separated from the piezoelectric element 10 when viewed from the direction orthogonal to the main surface 20a. When the electrodes 25 and 26 are arranged in a region sandwiched between the piezoelectric element 10 and the resin member 20, the piezoelectric element 10 comes into contact with the electrodes 25 and 26 and is against the main surfaces 30 a and 30 b of the vibration member 30. There is a risk of tilting. When the piezoelectric element 10 is pressure-bonded to the resin member 20, a force may be applied to the piezoelectric element 10 from the electrodes 25 and 26, so that the piezoelectric element body 11 may be cracked. If the electrodes 25 and 26 are separated from the piezoelectric element 10 when viewed from the direction orthogonal to the main surface 20a, the inclination of the piezoelectric element 10 and the cracking of the piezoelectric element body 11 can be suppressed.

  The adhesive layer 40 is insulative and covers the electrode 14. For this reason, a short circuit between the electrode 26 and the conductive resin layer 28 and the electrode 14 is prevented.

  In the vibration device 1, as described above, the area of the resin member 20 having insulation is larger than the area of the piezoelectric element 10 when viewed from the direction orthogonal to the main surface 20 a. For this reason, occurrence of a short circuit between the piezoelectric element 10 and the vibration member 30 is suppressed by the resin member 20. The adhesion area where the adhesive layer 50 adheres to the vibration member 30 is larger than the adhesion area where the adhesive layer 40 adheres to the resin member 20. For this reason, the displacement at the end of the vibration member 30 is improved as compared with the vibration device 1 in which the adhesion area between the resin member 20 and the piezoelectric element 10 and the adhesion area between the resin member 20 and the vibration member 30 are the same. Yes. That is, even when the piezoelectric element 10 is smaller than the vibration member 30, the displacement at the end of the vibration member 30 is ensured. Therefore, in the vibration device 1, the occurrence of a short circuit between the piezoelectric element 10 and the vibration member 30 is suppressed, and a sufficient displacement can be obtained at the end of the vibration member 30.

  The displacement of the vibration member 30 is the largest at the portion where the piezoelectric element 10 is bonded, and decreases as the distance from the piezoelectric element 10 increases. For this reason, the displacement of the vibration member 30 is minimum in the vicinity of the short side of the vibration member 30. In the vibrating device 1, the extending portion 21 is pulled out from the short side where the displacement of the vibrating member 30 is minimized, and thus is difficult to peel off from the vibrating member 30.

  Since the vibration member 30 made of metal has a larger coefficient of thermal expansion than the piezoelectric element 10, the vibration member 30 may be deformed by a temperature change. Since the rigidity is lower as the thickness is smaller, the vibration member 30 is more easily deformed as the thickness is smaller. Therefore, when the thickness of the vibration member 30 is small, an external force is applied to the piezoelectric element 10 due to the deformation of the vibration member 30 due to a temperature change, so that the piezoelectric element 10 is likely to be cracked. When the vibration member 30 is easily deformed, in the aspect in which the vibration member 30 is bonded to another member, peeling of the bond is likely to occur when the vibration device 1 is driven.

  In this regard, the thickness of the vibrating member 30 is greater than or equal to the thickness of the piezoelectric element 10 in the direction orthogonal to the main surface 20a. Therefore, since the thickness of the vibration member 30 is ensured, it is difficult to break. Since the thickness of the insulating resin member 20 is smaller than the thickness of the piezoelectric element 10 and the vibration member 30, the vibration of the vibration device 1 is easily recognized by human tactile sense.

  On the main surface 20 a of the resin member 20, a pair of electrodes 25 and 26 that are electrically connected to the piezoelectric element 10 are provided. For this reason, the electrodes 25 and 26 for applying a voltage to the piezoelectric element 10 are simply provided in a space-saving manner. According to the above configuration, a space for arranging the electrodes 25 and 26 is ensured, a short circuit between the piezoelectric element 10 and the vibration member 30 is suppressed, and a displacement at the end of the vibration member 30 is ensured.

  The preferred embodiments of the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  For example, the piezoelectric element 10 may have a laminated structure having one or a plurality of internal electrodes in the piezoelectric element body 11. In this case, the piezoelectric element 11 includes a plurality of piezoelectric layers, and the internal electrodes and the piezoelectric layers are alternately arranged.

  In the vibration device 1, the electrodes 12 and 13 are disposed on the main surface 11a of the piezoelectric element body 11, and the electrode 14 is disposed on the main surface 11b. However, the electrodes 12 and 13 are disposed on the main surface 11b. The electrode 14 may be disposed on the main surface 11a.

  Only the electrode 13 may be disposed on the main surface 11a without providing the electrode 12. In this case, the electrode 25 is electrically connected to the electrode 14 directly or through a conductive filler.

  The vibration member 30 may be a housing such as a device, or the vibration member 30 may be mounted on a housing such as a device by surface bonding.

  DESCRIPTION OF SYMBOLS 1 ... Vibration device, 10 ... Piezoelectric element, 11 ... Piezoelectric body, 11a, 11b ... Main surface of piezoelectric body, 12, 13, 14 ... Electrode of piezoelectric element, 20 ... Resin member, 20a, 20b ... Resin member Main surfaces, 25, 26 ... electrodes, 27, 28 ... conductive resin layers, 30 ... vibrating members, 30a, 30b ... main surfaces of vibrating members, 40, 50 ... adhesive layers.

Claims (3)

A piezoelectric element having a piezoelectric element body having first and second main surfaces opposed to each other, and first and second electrodes disposed on the first main surface;
An insulating resin member having a third main surface joined to the piezoelectric element and a fourth main surface facing the third main surface;
A vibration member made of metal, having a fifth main surface joined to the fourth main surface of the resin member and a sixth main surface facing the fifth main surface;
Third and fourth electrodes disposed on the third main surface of the resin member;
A first conductive resin layer connecting the first electrode and the third electrode;
A vibration device comprising: a second conductive resin layer connecting the second electrode and the fourth electrode.   The vibrating device according to claim 1, wherein the third and fourth electrodes are separated from the piezoelectric element when viewed from a direction orthogonal to the first main surface. The piezoelectric element and the third main surface of the resin member are joined by an insulating adhesive layer,
The piezoelectric element has a fifth electrode disposed on the second main surface and electrically connected to the first electrode,
The vibrating device according to claim 1, wherein the adhesive layer covers the fifth electrode.

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