Piezoelectric device

Abstract

To provide a piezoelectric device with improved sound pressure.SOLUTION: A piezoelectric device 1 includes a piezoelectric element 2, a diaphragm 3 on which the piezoelectric element 2 is arranged, a support portion 4 that supports the outer edge portion 31 of the diaphragm 3, an elastic member 5 disposed between the outer edge portion 31 of the diaphragm 3 and the support portion 4, and an adhesive member 6 that adheres the elastic member 5 to the outer edge portion 31 of the diaphragm 3 and the support portion 4.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a piezoelectric device.

Background Art

[0002] Patent Document 1 discloses an acoustic generator including a piezoelectric element, a diaphragm to which the piezoelectric element is attached, a first frame member and a second frame member that sandwich and support the outer peripheral portion of the diaphragm, a first adhesive that adheres the outer peripheral portion of the diaphragm to the first frame member, and a second adhesive that adheres the outer peripheral portion of the diaphragm to the second frame member. In this acoustic generator, the sound quality can be improved by making the elastic modulus of the first adhesive different from the elastic modulus of the second adhesive.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] One aspect of the present disclosure provides a piezoelectric device in which an improvement in sound pressure is achieved.

Means for Solving the Problems

[0005] A piezoelectric device according to one aspect of the present disclosure includes a piezoelectric element, a diaphragm on which the piezoelectric element is disposed, a support portion that supports the outer edge portion of the diaphragm, an elastic member disposed between the outer edge portion of the diaphragm and the support portion, and an adhesive member that adheres the elastic member to the outer edge portion of the diaphragm and the support portion.

[0006] In this piezoelectric device, an elastic member is disposed between the outer edge portion of the diaphragm and the support portion. Therefore, compared with a configuration in which the outer edge portion of the diaphragm is directly adhered to the support portion with an adhesive, when the piezoelectric element is driven and the diaphragm undergoes bending vibration, the vibration of the outer edge portion of the diaphragm is less likely to be inhibited. As a result, the sound pressure can be improved.

[0007] The diaphragm has a first main surface and a second main surface that face each other. The support portion has a first opposing surface that faces the outer edge portion of the first main surface and supports the outer edge portion of the first main surface. The elastic member has a first elastic layer disposed between the outer edge portion of the first main surface and the first opposing surface. The adhesive member may have a first adhesive layer that adheres the first elastic layer to the outer edge portion of the first main surface and a second adhesive layer that adheres the first elastic layer to the first opposing surface. Even when the outer edge portion of the first main surface of the diaphragm is supported by the first opposing surface of the support body in this way, since the first elastic layer is disposed between the outer edge portion of the first main surface of the diaphragm and the first opposing surface of the support body, the vibration of the outer edge portion of the diaphragm is less likely to be suppressed compared to a configuration in which the outer edge portion of the first main surface of the diaphragm is directly adhered to the first opposing surface of the support body.

[0008] The support portion has a second opposing surface that faces the outer edge portion of the second main surface and supports the outer edge portion of the second main surface. The elastic member has a second elastic layer disposed between the outer edge portion of the second main surface and the second opposing surface. The adhesive member may have a third adhesive layer that adheres the second elastic layer to the outer edge portion of the second main surface and a fourth adhesive layer that adheres the second elastic layer to the second opposing surface. Even when the outer edge portion of the second main surface of the diaphragm is supported by the second opposing surface of the support body in this way, since the second elastic layer is disposed between the outer edge portion of the second main surface of the diaphragm and the second opposing surface of the support body, the vibration of the outer edge portion of the diaphragm is less likely to be suppressed compared to a configuration in which the outer edge portion of the second main surface of the diaphragm is directly adhered to the second opposing surface of the support body.

[0009] The diaphragm has a side surface that connects the first main surface and the second main surface, and a space may be formed around the side surface. In this case, it can have a tuning function and can adjust the shift of the center of gravity of the diaphragm.

[0010] The support part may have a stopper that restricts the vibration range of the outer edge part of the diaphragm in a direction orthogonal to the thickness direction of the diaphragm. In this case, the vibration range of the outer edge part of the diaphragm in the direction orthogonal to the thickness direction of the diaphragm can be restricted.

[0011] A first through hole is provided in the outer edge part of the diaphragm, and the stopper may be disposed in the first through hole. In this case, by adjusting the dimensions of the first through hole and the stopper, the vibration range of the outer edge part of the diaphragm can be easily adjusted.

[0012] The elastic member may be provided with a second through hole that overlaps the first through hole when viewed from the thickness direction of the diaphragm. In this case, by disposing the stopper in the second through hole, the deformation of the elastic member is less likely to be inhibited by the stopper. Therefore, the vibration of the outer edge part of the diaphragm is less likely to be inhibited.

[0013] The support part has a pair of opposing members that face each other through the outer edge part of the diaphragm and sandwich the outer edge part of the diaphragm, and a fastening member that fastens the pair of opposing members, and the stopper may be constituted by the fastening member. In this case, the distance between the pair of opposing members can be easily adjusted by the fastening member.

Advantages of the Invention

[0014] According to one aspect of the present invention, a piezoelectric device in which the sound pressure is improved is provided.

Brief Description of the Drawings

[0015]

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DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant descriptions are omitted.

[0017] FIG. 1 is a plan view of a piezoelectric device according to an embodiment. FIGS. 2 and 3 are cross-sectional views of the piezoelectric device of FIG. 1. The piezoelectric device 1 shown in FIGS. 1 to 3 is a device used as an acoustic device such as a speaker, and can be mounted on an electronic device that emits sound, such as a television or a smartphone. The piezoelectric device 1 includes a piezoelectric element 2, a diaphragm 3, a support portion 4, an elastic member 5, and an adhesive member 6.

[0018] The piezoelectric element 2 has a piezoelectric body 20. In the present embodiment, the piezoelectric body 20 is configured by laminating a plurality of piezoelectric layers, for example. The piezoelectric body 20 has, for example, a rectangular parallelepiped shape and a rectangular shape in plan view. The “rectangular parallelepiped shape” includes a shape of a rectangular parallelepiped with chamfered corners and ridge lines, and a shape of a rectangular parallelepiped with rounded corners and ridge lines.

[0019] Each piezoelectric layer is made of a piezoelectric ceramic material. Examples of the piezoelectric ceramic material include PZT [Pb(Zr,Ti)O3], PT (PbTiO3), PLZT [(Pb,La)(Zr,Ti)O3], or barium titanate (BaTiO3). The piezoelectric element is composed of, for example, a sintered body of a ceramic green sheet containing the above-described piezoelectric ceramic material. In the actual piezoelectric element 20, each piezoelectric layer is integrated to such an extent that the boundary between each piezoelectric layer cannot be recognized.

[0020] The piezoelectric element 2 has a pair of external electrodes (not shown) disposed on the outer surface of the piezoelectric element 20 and a plurality of internal electrodes (not shown) disposed inside the piezoelectric element 20. Each external electrode and each internal electrode are formed of a conductive material. Examples of the conductive material include Ag, Pd, and Ag-Pd alloy. A wiring member (not shown), such as a flexible printed circuit board, is electrically connected to the pair of external electrodes. One end side of the wiring member is electrically and physically connected to the pair of external electrodes of the piezoelectric element 2, and the other end side of the wiring member is electrically and physically connected to an electronic device on which the piezoelectric device 1 is mounted.

[0021] The diaphragm 3 has a first main surface 3a and a second main surface 3b facing each other, and a side surface 3c connecting the first main surface 3a and the second main surface 3b. The facing direction D of the first main surface 3a and the second main surface 3b coincides with the thickness direction of the diaphragm 3. A space S is formed around the side surface 3c. The entire surface of the side surface 3c faces the space S. The width of the space S (the length in the direction orthogonal to the side surface 3c) is, for example, 10 μm or more.

[0022] In this embodiment, the diaphragm 3 has a rectangular shape in a plan view (when viewed from the facing direction D). The "rectangular shape" includes a shape with chamfered corners and a shape with rounded corners. The diaphragm 3 is formed in a thin plate shape from, for example, a metal material or a resin material. Examples of the metal material include Ni-Fe alloy, Ni, brass, stainless steel, and the like. The thickness of the diaphragm 3 is, for example, 0.1 mm or more and 3 mm or less. The width of the space S is set in consideration of the shift of the center of gravity due to manufacturing errors (for example, several μm to several tens of μm).

[0023] The piezoelectric element 2 is disposed on the diaphragm 3. The piezoelectric element 2 is disposed on at least one of the first main surface 3a and the second main surface 3b. In this embodiment, the piezoelectric element 2 is disposed on the second main surface 3b. The piezoelectric element 2 is disposed such that the long side of the piezoelectric element 2 is parallel to the long side of the diaphragm 3 when viewed from the facing direction D. The thickness direction of the piezoelectric element 2 coincides with the thickness direction of the diaphragm 3. The piezoelectric element 2 is attached to the first main surface 3a by, for example, an adhesive member made of a thermosetting resin or a double-sided tape. The piezoelectric element 2 is disposed at the center of the diaphragm 3 when viewed from the facing direction D. When the piezoelectric element 2 is driven, the diaphragm 3 undergoes bending vibration.

[0024] The support portion 4 supports the outer edge portion 31 of the diaphragm 3. The support portion 4 includes a first opposing member 41, a second opposing member 42, and a connecting member 43. The first opposing member 41 and the second opposing member 42 face each other via the outer edge portion 31 of the diaphragm 3 in the facing direction D. The first opposing member 41 and the second opposing member 42 sandwich the outer edge portion 31. The outer edge portion 31 of the diaphragm 3 includes the outer edge portion 31a of the first main surface 3a and the outer edge portion 31b of the second main surface 3b.

[0025] The first opposing member 41 has a first opposing surface 41a that opposes the outer edge portion 31a of the first main surface 3a. The first opposing surface 41a supports the outer edge portion 31a of the first main surface 3a. The second opposing member 42 has a second opposing surface 42a that opposes the outer edge portion 31b of the second main surface 3b. The second opposing surface 42a supports the outer edge portion 31b of the second main surface 3b. The outer edge portion 31 is disposed between the first opposing surface 41a and the second opposing surface 42a. The first opposing surface 41a and the second opposing surface 42a restrict displacement of the outer edge portion 31 in the opposing direction D. In the present embodiment, the outer edge portion 31 is sandwiched between the first opposing surface 41a and the second opposing surface 42a.

[0026] The connecting member 43 connects the first opposing member 41 and the second opposing member 42 to each other. The connecting member 43 is disposed between the first opposing member 41 and the second opposing member 42 and can be said to be sandwiched between the first opposing member 41 and the second opposing member 42. The connecting member 43 has a third opposing surface 43a that opposes the side surface 3c of the diaphragm 3. In a state where the piezoelectric element 2 is not being driven, the side surface 3c and the third opposing surface 43a are separated from each other with a space S therebetween.

[0027] In the present embodiment, the support portion 4 is a rectangular frame-shaped member or a rectangular ring-shaped member having a C-shaped cross section. The first opposing member 41, the second opposing member 42, and the connecting member 43 are each a rectangular frame-shaped member or a rectangular ring-shaped member having a rectangular cross section. The first opposing member 41 and the second opposing member 42 have the same shape as each other. The outer peripheral surfaces of the first opposing member 41, the second opposing member 42, and the connecting member 43 constitute the same plane as each other. The inner peripheral surfaces of the first opposing member 41 and the second opposing member 42 are located inside the inner peripheral surface of the connecting member 43. The first opposing member 41, the second opposing member 42, and the connecting member 43 are, for example, formed of a single member.

[0028] The elastic member 5 is disposed between the outer edge portion 31 of the diaphragm 3 and the support portion 4. The elastic member 5 is adhered to the outer edge portion 31 of the diaphragm 3 and the support portion 4 by an adhesive member 6. The elastic member 5 has a first elastic layer 51 and a second elastic layer 52. The first elastic layer 51 is disposed between the outer edge portion 31a of the first main surface 3a and the first opposing surface 41a. The second elastic layer 52 is disposed between the outer edge portion 31b of the second main surface 3b and the second opposing surface 42a.

[0029] Each elastic layer 51, 52 is made of, for example, resin or rubber. Each elastic layer 51, 52 is made of a material having no adhesiveness, for example. The first elastic layer 51 and the second elastic layer 52 have the same configuration (elastic modulus and thickness) as each other, for example. The elastic modulus of each elastic layer 51, 52 is, for example, 1 MPa or more and 500 MPa or less. The thickness of each elastic layer 51, 52 is, for example, 0.1 mm or more and 20 mm or less.

[0030] The adhesive member 6 adheres the elastic member 5 to the outer edge portion 31 of the diaphragm 3 and the support portion 4. The adhesive member 6 has a first adhesive layer 61, a second adhesive layer 62, a third adhesive layer 63, and a fourth adhesive layer 64. The first adhesive layer 61 is provided between the first elastic layer 51 and the outer edge portion 31a of the first main surface 3a. The first adhesive layer 61 adheres the first elastic layer 51 to the outer edge portion 31a of the first main surface 3a. The second adhesive layer 62 is provided between the first elastic layer 51 and the first opposing surface 41a. The second adhesive layer 62 adheres the first elastic layer 51 to the first opposing surface 41a. The third adhesive layer 63 is provided between the second elastic layer 52 and the outer edge portion 31b of the second main surface 3b. The third adhesive layer 63 adheres the second elastic layer 52 to the outer edge portion 31b of the second main surface 3b. The fourth adhesive layer 64 is provided between the second elastic layer 52 and the second opposing surface 42a. The fourth adhesive layer 64 adheres the second elastic layer 52 to the second opposing surface 42a.

[0031] Each of the adhesive layers 61 to 64 is made of, for example, an adhesive and has adhesiveness. Examples of the adhesive constituting each of the adhesive layers 61 to 64 include epoxy thermosetting resins. The thickness of each of the adhesive layers 61 to 64 is thinner than the thickness of each of the elastic layers 51 and 52. The thickness of each of the adhesive layers 61 to 64 is, for example, 5 μm or more and 200 μm or less.

[0032] FIG. 4 is a cross-sectional view showing the piezoelectric device during driving. In the piezoelectric device 1, when the piezoelectric element 2 is driven, the diaphragm 3 undergoes bending vibration. When the diaphragm 3 bends, as shown in FIG. 4, when viewed from the facing direction D, the outer edge portion 31 moves inward so that the area of the diaphragm 3 becomes smaller. The vibration of the diaphragm 3 in the facing direction D is smaller than the vibration in the direction orthogonal to the facing direction D of the diaphragm 3. Therefore, in FIG. 4, only the movement in the direction orthogonal to the facing direction D of the diaphragm 3 is shown, and the bending of the diaphragm 3 is not shown, but the diaphragm 3 is actually bent.

[0033] When the diaphragm 3 bends, if the outer edge portion 31 is strongly constrained by the support portion 4, the movement of the outer edge portion 31 is inhibited, and as a result, the vibration of the diaphragm 3 is inhibited. Therefore, in the piezoelectric device 1, an elastic member 5 is disposed between the outer edge portion 31 and the support portion 4. Thus, compared with a configuration in which the outer edge portion 31 is directly adhered to the diaphragm 3 with an adhesive, it is difficult to inhibit the vibration of the outer edge portion 31 when the diaphragm 3 undergoes bending vibration. As a result, the sound pressure can be improved.

[0034] Instead of providing the elastic member 5, a configuration in which an adhesive having elasticity is provided thickly is also conceivable, but it is difficult to control the thickness of the adhesive. Therefore, it is difficult to realize a desired elastic modulus. By providing the elastic member 5 as a separate member from the adhesive member 6, a desired elastic modulus can be easily realized.

[0035] The first elastic layer 51 and the second elastic layer 52 have the same configuration as each other in terms of elastic modulus, thickness, etc. For this reason, the influence exerted by the elastic member 5 on the diaphragm 3 can be made equivalent between the first main surface 3a side and the second main surface 3b side. As a result, the diaphragm 3 can be bent and vibrated in a well-balanced manner.

[0036] The outer edge portion 31a of the first main surface 3a is supported by the first opposing surface 41a of the first opposing member 41. The outer edge portion 31b of the second main surface 3b is supported by the second opposing surface 42a of the second opposing member 42. That is, the outer edge portion 31 is disposed between the first opposing surface 41a of the first opposing member 41 and the second opposing surface 42a of the second opposing member 42, and is supported by the support portion 4 on both sides. More specifically, the outer edge portion 31 is sandwiched between the first opposing surface 41a and the second opposing surface 42a. Therefore, compared with the configuration in which the outer edge portion 31 is supported by the support portion 4 on one side, the displacement of the outer edge portion 31 is more reliably restricted in the thickness direction (opposing direction D) of the diaphragm 3. Thus, the amplitude of the diaphragm 3 can be increased.

[0037] In the piezoelectric device 1, a space S is formed around the side surface 3c of the diaphragm 3, and the entire side surface 3c faces the space S. The side surface 3c and the third opposing surface 43a of the support portion 4 are separated from each other with the space S therebetween. Thereby, the shift of the center of gravity of the diaphragm 3 can be adjusted.

[0038] As described above, the embodiments of the present invention have been described. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the gist thereof.

[0039] In the piezoelectric device 1, the piezoelectric element 2 and the diaphragm 3 have a rectangular shape in plan view, and the support portion 4 has a rectangular frame shape or a rectangular ring shape, but the present invention is not limited thereto. FIG. 5 is a plan view of a piezoelectric device according to a first modification. As shown in FIG. 5, in the piezoelectric device 1A according to the first modification, the piezoelectric element 2 and the diaphragm 3 have a circular shape in plan view, and the support portion 4 has a circular frame shape or a circular ring shape in plan view.

[0040] FIG. 6 is a cross-sectional view of the piezoelectric device 1A in FIG. 5. In FIG. 6, illustrations other than the diaphragm 3 and the support portion 4 are omitted. In the piezoelectric device 1A, the distance between the piezoelectric element 2 and the support portion 4 is uniform in all directions orthogonal to the facing direction D (see FIG. 2). Therefore, in the piezoelectric device 1A, as shown in FIG. 6, the diaphragm 3 can be vibrated uniformly in any direction orthogonal to the facing direction D (see FIG. 2). Also in the piezoelectric device 1A, since the elastic member 5 is disposed between the outer edge portion 31 and the support portion 4, the same effect as that of the piezoelectric device 1 is achieved.

[0041] FIG. 7 is a plan view of the piezoelectric device according to the second modification. FIGS. 8 to 11 are cross-sectional views of the piezoelectric device in FIG. 7. The piezoelectric device 1B according to the second modification is different from the piezoelectric device 1 in that it includes a plurality of fastening members 7. The piezoelectric device 1B has a configuration equivalent to that of the piezoelectric device 1 except for these points. Also in the piezoelectric device 1B, since the elastic member 5 is disposed between the outer edge portion 31 and the support portion 4, the same effect as that of the piezoelectric device 1 is achieved.

[0042] A plurality of first through-holes 32 are formed in the outer edge portion 31 of the diaphragm 3 corresponding to the plurality of fastening members 7. The first through-holes 32 penetrate the outer edge portion 31 in the facing direction D. The first through-holes 32 have, for example, a circular cross-sectional shape. A plurality of second through-holes 53 are formed in each of the elastic layers 51, 52 corresponding to the plurality of fastening members 7. The second through-holes 53 penetrate each of the elastic layers 51, 52 in the facing direction D. The second through-holes 53 have, for example, a circular cross-sectional shape. Each of the second through-holes 53 overlaps with each of the plurality of first through-holes 32 when viewed from the facing direction D. When viewed from the facing direction D, the inner edges of the first through-holes 32 and the inner edges of the second through-holes 53 overlap each other.

[0043] The plurality of fastening members 7 fasten the first opposing member 41 and the second opposing member 42. In the present embodiment, the fastening members 7 are disposed at each of the four corner portions of the support portion 4 and at each of the central portions of the four side portions. That is, the piezoelectric device 1B includes eight fastening members 7.

[0044] The fastening member 7 is, for example, a bolt and has a head portion 7a and a shaft portion 7b. The head portion 7a is disposed on the second opposing member 42. The shaft portion 7b has a circular cross-section and extends along the opposing direction D. The shaft portion 7b includes a proximal end portion 7c, a distal end portion 7d, and an intermediate portion 7e. The proximal end portion 7c penetrates the second opposing member 42 in the opposing direction D and is fastened to the second opposing member 42. The distal end portion 7d is fastened to the first opposing member 41. The intermediate portion 7e is disposed within the first through-hole 32 and within the pair of second through-holes 53 and connects the proximal end portion 7c and the distal end portion 7d.

[0045] The fastening member 7 has a proximal end portion 7c and a distal end portion 7d fixed to the support portion 4 and also has an intermediate portion 7e disposed within the first through-hole 32, thereby functioning as a stopper that restricts the vibration range of the outer edge portion 31 of the diaphragm 3 in a direction orthogonal to the opposing direction D. That is, the piezoelectric device 1B includes a stopper constituted by the fastening member 7.

[0046] As shown in FIG. 9, the cross-sectional dimension of the first through-hole 32 is set to be larger than the cross-sectional dimension of the intermediate portion 7e. The difference between the cross-sectional dimension of the first through-hole 32 and the cross-sectional dimension of the intermediate portion 7e sets the movable range (movement range) of the diaphragm 3. The cross-sectional dimensions of the first through-hole 32 and the intermediate portion 7e are, for example, the maximum lengths of the first through-hole 32 and the intermediate portion 7e in the moving direction (direction orthogonal to the opposing direction D) of the outer edge portion 31 of the diaphragm 3. When the cross-sectional shapes of the first through-hole 32 and the intermediate portion 7e are circular, the cross-sectional dimension is the diameter.

[0047] As shown in FIG. 10, the cross-sectional dimension of each second through-hole 53 is set to be larger than the cross-sectional dimension of the intermediate portion 7e. The cross-sectional dimension of each second through-hole 53 is set to be equivalent to the cross-sectional dimension of the first through-hole 32. For this reason, when the outer edge portion 31 of the diaphragm 3 moves, interference between the elastic member 5 and the intermediate portion 7e is suppressed.

[0048] In the piezoelectric device 1B, the first opposing member 41 and the second opposing member 42 are fastened by the fastening member 7. According to the fastening member 7, the distance between the first opposing surface 41a and the second opposing surface 42a can be easily adjusted to the total thickness of the diaphragm 3, the elastic member 5, and the adhesive member 6. Thereby, the diaphragm 3, the elastic member 5, and the adhesive member 6 can be arranged between the first opposing surface 41a and the second opposing surface 42a without any gaps.

[0049] Since the fastening member 7 functions as a stopper, the vibration range of the outer edge portion 31 can be restricted. Therefore, even if the adhesion by the adhesive member 6 is peeled off, the diaphragm 3 is suppressed from falling off from the support portion 4. Thereby, the diaphragm 3 can be stably supported by the support portion 4. Since the stopper is constituted by the fastening member 7, there is no need to provide a separate member as the stopper.

[0050] The intermediate portion 7e of the shaft portion 7b of the fastening member 7 is disposed in the first through hole 32. Therefore, by adjusting the dimensions of the first through hole 32 and the intermediate portion 7e, the vibration range of the outer edge portion 31 can be easily adjusted. Further, since the intermediate portion 7e is disposed in each second through hole 53, the deformation of the elastic member 5 is hardly inhibited by the intermediate portion 7e. Therefore, the vibration of the outer edge portion 31 is hardly inhibited.

[0051] In the piezoelectric device 1, the support portion 4 supports the outer edge portion 31 of the diaphragm 3 on both sides, but it may be supported on one side. FIG. 12 is a cross-sectional view of a piezoelectric device according to a third modification. As shown in FIG. 12, the piezoelectric device 1C according to the third modification is different from the piezoelectric device 1 in that the support portion 4 supports the outer edge portion 31 on one side. For this reason, the support portion 4 has the first opposing member 41 and does not have the second opposing member 42 and the connecting member 43. The elastic member 5 has the first elastic layer 51 and does not have the second elastic layer 52. The adhesive member 6 has the first adhesive layer 61 and the second adhesive layer 62 and does not have the third adhesive layer 63 and the fourth adhesive layer 64. Also in the piezoelectric device 1C, since the elastic member 5 is disposed between the outer edge portion 31 and the support portion 4, the same effect as that of the piezoelectric device 1 is achieved.

[0052] The configurations of the respective modified examples may be combined with each other. For example, the piezoelectric device 1A may include a plurality of fastening members 7. In the piezoelectric device 1A, the support portion 4 may support the outer edge portion 31 of the diaphragm 3 on one side.

[0053] In the piezoelectric devices 1, 1A, and 1B, the first opposing member 41, the second opposing member 42, and the connecting member 43 may be formed of a single member, or may be formed of separate members. In the piezoelectric device 1B, since the first opposing member 41 and the second opposing member 42 are fastened by the fastening member 7, the support portion 4 may not have the connecting member 43. Also in the piezoelectric device 1A, if the fastening member 7 is provided, the support portion 4 may not have the connecting member 43.

[0054] The piezoelectric device 1B includes the fastening member 7 as a stopper, but the stopper may have a portion disposed in the first through hole 32 and a portion fixed to the support portion 4. The fixing method of the stopper is not limited to fastening. For example, it may be fixed to at least one of the first opposing member 41 and the second opposing member 42 by adhesion. The stopper may be, for example, a protrusion protruding from the first opposing surface 41a or the second opposing surface 42a into the first through hole 32.

[0055] In the piezoelectric device 1C, the piezoelectric element 2 may be disposed on the first main surface 3a.

[0056] In the piezoelectric devices 1, 1A, 1B, and 1C, the support portion 4 has a frame shape or an annular shape and supports the outer edge portion 31 over the entire circumference, but is not limited thereto. The support portion 4 only needs to be configured to support the diaphragm 3, and may be configured to support a part of the outer edge portion 31. For example, if the diaphragm 3 is rectangular in plan view, a portion corresponding to a pair of short sides of the outer edge portion 31 may be configured to be supportable.

Description of Reference Numerals

[0057] 1, 1A, 1B, 1C… Piezoelectric device, 2… Piezoelectric element, 3… Diaphragm, 3a… First main surface, 3b… Second main surface, 3c… Side surface, 4… Support portion, 5… Elastic member, 6… Adhesive member, 7… Fastening member, 31… Outer edge portion, 32… First through hole, 41… First opposing member, 41a… First opposing surface, 42… Second opposing member, 42a… Second opposing surface, 51… First elastic layer, 52… Second elastic layer, 53… Second through hole, 61… First connection layer, 62… Second connection layer, 63… Third connection layer, 64… Fourth connection layer, S… Space.

Claims

1. A piezoelectric element, a diaphragm on which the piezoelectric element is disposed, a support portion that supports an outer edge portion of the diaphragm, an elastic member having a square cross-section disposed between the outer edge portion of the diaphragm and the support portion, and an adhesive member that adheres the elastic member to the outer edge portion of the diaphragm and the support portion, The diaphragm has a first main surface and a second main surface facing each other, and a side surface connecting the first main surface and the second main surface, The elastic member has an outer surface facing the same direction as the side surface, A space is formed around the side surface and the outer surface, The support portion is a stopper that restricts a vibration range of the outer edge portion of the diaphragm in a direction orthogonal to the thickness direction of the diaphragm, and has a stopper disposed in a first through hole provided in the outer edge portion of the diaphragm. A piezoelectric device.

2. The support portion faces an outer edge portion of the first main surface and has a first opposing surface that supports the outer edge portion of the first main surface, The elastic member has a first elastic layer disposed between the outer edge portion of the first main surface and the first opposing surface, The adhesive member has a first adhesive layer that adheres the first elastic layer to the outer edge portion of the first main surface and a second adhesive layer that adheres the first elastic layer to the first opposing surface. The piezoelectric device according to claim 1.

3. The support portion faces an outer edge portion of the second main surface and has a second opposing surface that supports the outer edge portion of the second main surface, The elastic member has a second elastic layer disposed between the outer edge portion of the second main surface and the second opposing surface, The adhesive member has a third adhesive layer that adheres the second elastic layer to the outer edge portion of the second main surface and a fourth adhesive layer that adheres the second elastic layer to the second opposing surface. The piezoelectric device according to claim 2.

4. A piezoelectric element, a diaphragm on which the piezoelectric element is disposed, a support portion that supports an outer edge portion of the diaphragm, an elastic member disposed between the outer edge portion of the diaphragm and the support portion, and an adhesive member that adheres the elastic member to the outer edge portion of the diaphragm and the support portion, The diaphragm has a first main surface and a second main surface facing each other, and a side surface connecting the first main surface and the second main surface, The elastic member has an outer surface facing the same direction as the side surface, A space is formed around the side surface and the outer surface, The support portion has a stopper that restricts a vibration range of the outer edge portion of the diaphragm in a direction orthogonal to the thickness direction of the diaphragm, A first through hole is provided in the outer edge portion of the diaphragm, The stopper is disposed in the first through hole, A piezoelectric device.

5. The elastic member is provided with a second through hole that overlaps the first through hole when viewed from the thickness direction of the diaphragm, The piezoelectric device according to claim 4.

6. A piezoelectric element, a diaphragm on which the piezoelectric element is disposed, a support portion that supports an outer edge portion of the diaphragm, an elastic member disposed between the outer edge portion of the diaphragm and the support portion, and an adhesive member that adheres the elastic member to the outer edge portion of the diaphragm and the support portion, The diaphragm has a first main surface and a second main surface facing each other, and a side surface connecting the first main surface and the second main surface, The elastic member has an outer surface facing the same direction as the side surface, A space is formed around the side surface and the outer surface, The support portion has a stopper that limits the vibration range of the outer edge portion of the diaphragm in a direction orthogonal to the thickness direction of the diaphragm, The support portion includes a pair of opposing members that face each other via the outer edge portion of the diaphragm and sandwich the outer edge portion of the diaphragm, and a fastening member that fastens the pair of opposing members, The stopper is constituted by the fastening member, Piezoelectric device.

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