JP2018126701A - Vibration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration device which is not easily damaged and enables vibration to be perceived by tactile senses of humans.SOLUTION: A vibration device 1 includes: a piezoelectric element 10; an insulative resin member 20 having a first major surface 20a joined to the piezoelectric element 10 and a second major surface 20b facing the first major surface 20a; and a vibration member 30 which has a third major surface 30a joined to the second major surface 20b of the resin member 20 and a fourth major surface 30b facing the third major surface 30a and is made of metal. A thickness of the resin member 20 is smaller than a thickness of the piezoelectric element 10 and a thickness of the vibration member 30 in a direction perpendicular to the first major surface 20a. A thickness of the vibration member 30 is larger than or equal to a thickness of the piezoelectric element 10 in the direction perpendicular to the first major surface 20a.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 made of metal 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 Documents). 1).

JP 2013-219250 A

  The vibration of the vibration device is easily recognized by a human tactile sense when the vibration frequency is 100 Hz to 500 Hz. The displacement of the vibration device is larger as the vibration frequency of the piezoelectric element is closer to the resonance frequency of the entire vibration device. For this reason, by being configured so that the resonance frequency of the entire vibration device is in the vicinity of 100 Hz to 500 Hz, a sufficient displacement can be ensured at a vibration frequency that is easily recognized by a human tactile sense. Therefore, in order to ensure the ease of recognition by human tactile sense, the thickness of the member bonded to the piezoelectric element is made small in order to keep the resonance frequency of the entire vibration device in the vicinity of 100 Hz to 500 Hz. Is desirable.

  However, in general, a vibration member made of metal has a higher coefficient of thermal expansion than a piezoelectric element, and thus the vibration member may be deformed due to a temperature change. Since the rigidity is lower as the thickness is smaller, the vibration member is more easily deformed as the thickness is smaller. Therefore, if the thickness of the vibrating member is small, an external force is applied to the piezoelectric element due to the deformation of the vibrating member due to a temperature change, so that the piezoelectric element is likely to be cracked. When the vibration member is easily deformed, when the vibration device is driven in a mode in which the vibration member is bonded to another member, peeling of the bond is likely to occur.

  An object of the present invention is to provide a vibration device that is not easily damaged and that vibrations are easily recognized by human tactile sense.

  The vibration device according to the present invention includes a piezoelectric element, an insulating resin member having a first main surface bonded to the piezoelectric element, and a second main surface facing the first main surface, and a second resin member. A resin member having a third main surface joined to the main surface and a fourth main surface facing the third main surface, and a vibration member made of metal, in a direction perpendicular to the first main surface. The thickness of the vibration member is smaller than the thickness of the piezoelectric element and the thickness of the vibration member, and the thickness of the vibration member is greater than or equal to the thickness of the piezoelectric element in the direction orthogonal to the first main surface.

  In the vibration device according to the present invention, since the thickness of the vibration member is secured, the vibration device is hardly damaged. Since the thickness of the insulating resin member is smaller than the thickness of the piezoelectric element and the vibration member, the vibration of the vibration device is easily recognized by the sense of touch.

  A pair of electrodes electrically connected to the piezoelectric element may be provided on the first main surface of the resin member. In this case, an electrode for applying a voltage to the piezoelectric element is simply provided in a space-saving manner.

  ADVANTAGE OF THE INVENTION According to this invention, the vibration device which cannot be damaged easily and a vibration can be easily recognized by human tactile sense can be provided.

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 mm × 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 due to 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, 20 ... Resin member, 20a, 20b ... Main surface of resin member, 25, 26 ... Electrode, 30 ... Vibration member, 30a, 30b ... Main surface of vibration member.

Claims (2)

A piezoelectric element;
An insulating resin member having a first main surface joined to the piezoelectric element and a second main surface facing the first main surface;
And having a third main surface joined to the second main surface of the resin member and a fourth main surface facing the third main surface, and a vibration member made of metal,
In the direction orthogonal to the first main surface, the thickness of the resin member is smaller than the thickness of the piezoelectric element and the thickness of the vibration member,
In the direction orthogonal to the first main surface, the vibration member has a thickness greater than or equal to the thickness of the piezoelectric element.   The vibration device according to claim 1, wherein a pair of electrodes electrically connected to the piezoelectric element is provided on the first main surface of the resin member.

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