JP2022115339A - vibration device - Google Patents

Abstract

An object of the present invention is to provide a vibrating device capable of obtaining desired characteristics.
A vibration device (1) includes a piezoelectric element (3) having a piezoelectric element (11), an internal electrode arranged in the piezoelectric element (11), an external electrode connected to the internal electrode, and principal surfaces facing each other. a diaphragm 5 having a main surface 5a and a main surface 5b, and on which the piezoelectric element 3 is arranged; A first bending elastic modulus for bending along the direction D1 is different from a second bending elastic modulus for bending along a second direction D2 intersecting the first direction D1.
[Selection drawing] Fig. 1

Description

The present invention relates to vibration devices.

A vibrating device includes a piezoelectric element and a diaphragm on which the piezoelectric element is arranged (see, for example, Patent Document 1).

JP-A-4-70100

An object of one aspect of the present invention is to provide a vibrating device that provides desired characteristics.

A vibrating device according to one aspect of the present invention includes a piezoelectric element having an element body, an internal electrode arranged in the element body, an external electrode connected to the internal electrode, and a first main surface facing each other. and a vibration plate having a second principal surface and being flexible, wherein the piezoelectric element is disposed, the vibration plate having the first principal surface and the second principal surface facing each other A first flexural modulus for bending along a first direction when viewed from the direction is different from a second flexural modulus for bending along a second direction intersecting the first direction.

In the vibration device according to one aspect of the present invention, the bending elastic modulus of the diaphragm on which the piezoelectric element is arranged differs between the first direction and the second direction. Therefore, in a vibrating device, by changing the arrangement direction (position) of the piezoelectric element with respect to the diaphragm, the amplification factor, displacement amount, etc. of the diaphragm with respect to the displacement of the piezoelectric element change. ) are different. Therefore, the vibrating device has the desired characteristics.

In one embodiment, the diaphragm is made of resin containing filler, and the longitudinal direction of the filler may be along the first direction or the second direction. In this configuration, since the bending elastic modulus of the diaphragm differs depending on the orientation direction of the filler, the diaphragm can have different bending elastic moduli in the first direction and the second direction.

In one embodiment, the element has a rectangular parallelepiped shape, the diaphragm has a first flexural modulus higher than the second flexural modulus, and the piezoelectric element extends along the length of the element when viewed from the opposite direction. It may be arranged on the diaphragm so that the direction is along the second direction. In this configuration, the diaphragm is less likely to bend (flexure) along the first direction and tends to bend (flexure) along the second direction. In this configuration, by arranging the piezoelectric element on the diaphragm so that the longitudinal direction of the element of the piezoelectric element is along the second direction, the displacement of the piezoelectric element is transmitted to the diaphragm while suppressing excessive bending of the diaphragm. be able to.

In one embodiment, the element has a rectangular parallelepiped shape, the diaphragm has a first flexural modulus higher than the second flexural modulus, and the piezoelectric element extends along the length of the element when viewed from the opposite direction. It may be arranged on the diaphragm so that the direction is along the first direction. In this configuration, the diaphragm is less likely to bend (flexure) along the first direction and tends to bend (flexure) along the second direction. In this configuration, by arranging the piezoelectric element on the diaphragm so that the longitudinal direction of the element of the piezoelectric element is along the first direction, the displacement of the piezoelectric element can be directly transmitted to the diaphragm.

In one embodiment, the element has a cubic shape, the diaphragm has a first flexural modulus higher than the second flexural modulus, and the piezoelectric element is positioned on each side of the element when viewed from opposite directions. The sides may be arranged on the diaphragm along the first direction or the second direction. With this configuration, the displacement of the piezoelectric element can be directly transmitted to the diaphragm while suppressing excessive bending of the diaphragm.

In one embodiment, the element has a rectangular parallelepiped shape, the diaphragm has a first flexural modulus higher than the second flexural modulus, and the piezoelectric element extends along the length of the element when viewed from the opposite direction. It may be arranged on the diaphragm so that the direction intersects the first direction and the second direction.

In one embodiment, the element has a cubic shape, the diaphragm has a first flexural modulus higher than the second flexural modulus, and the piezoelectric element is positioned on each side of the element when viewed from opposite directions. The diaphragm may be arranged such that the sides intersect the first direction and the second direction.

According to one aspect of the invention, desired properties are obtained.

FIG. 1 is a perspective view showing a vibration device according to one embodiment. 2 is an exploded perspective view of the vibration device shown in FIG. 1. FIG. FIG. 3 is a plan view of the vibration device. FIG. 4 is an exploded perspective view of the piezoelectric element. FIG. 5 is a diagram showing a cross-sectional configuration of a piezoelectric element. FIG. 6(a) is a diagram showing the state of the diaphragm when the diaphragm is folded along the first direction, and FIG. 6(b) is a diagram showing the state of the diaphragm when the diaphragm is folded along the second direction. It is a figure which shows the state of a diaphragm. FIG. 7 is a plan view of a vibration device according to another embodiment. FIG. 8 is a plan view of a vibration device according to another embodiment. FIG. 9 is a plan view of a vibration device according to another embodiment. FIG. 10 is a plan view of a vibration device according to another embodiment. FIG. 11 is a plan view of a vibration device according to another embodiment.

Preferred embodiments of the present invention will now 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 overlapping descriptions are omitted.

FIG. 1 is a perspective view showing a vibration device according to one embodiment. FIG. 2 is an exploded perspective view of the vibration device. FIG. 3 is a plan view of the vibration device. As shown in FIGS. 1, 2 and 3, the vibrating device 1 includes a piezoelectric element 3 and a vibrating plate 5. As shown in FIG. Vibration device 1 is, for example, an acoustic device used as a speaker or a buzzer. A wiring member 50 is connected to the piezoelectric element 3 in the vibration device 1 . The wiring member 50 is, for example, a flexible printed circuit board (FPC) or a flexible flat cable (FFC). The wiring member 50 is electrically connected to external electrodes 13, 14, 15, which will be described later.

The piezoelectric element 3 is of a bimorph type and has a piezoelectric body 11 and a plurality of external electrodes 13 , 14 and 15 . In this embodiment, the piezoelectric element 3 has three external electrodes 13 , 14 , 15 .

The piezoelectric element 11 has a rectangular parallelepiped shape. The piezoelectric body 11 has a pair of principal surfaces 11a and 11b (first and second principal surfaces) facing each other, a pair of side faces 11c facing each other, and a pair of side faces 11e facing each other. have. The rectangular parallelepiped shape includes, for example, a rectangular parallelepiped shape with chamfered corners and edges, and a rectangular parallelepiped shape with rounded corners and edges. The direction in which the pair of side surfaces 11c are opposed is the first direction D1. The first direction D1 is also a direction orthogonal to each side surface 11e. The direction in which the pair of side surfaces 11c are opposed is the second direction D2. The second direction D2 is also a direction orthogonal to each side surface 11c. The direction in which the pair of main surfaces 11a and 11b face is the third direction D3. The third direction D3 is also a direction perpendicular to the main surfaces 11a and 11b.

Each principal surface 11a, 11b has a pair of long sides and a pair of short sides. Each principal surface 11a, 11b has a rectangular shape with a pair of long sides and a pair of short sides. That is, the piezoelectric element 3 (piezoelectric body 11) has a rectangular shape having a pair of long sides and a pair of short sides in plan view. Rectangular shapes include, for example, shapes with chamfered corners and shapes with rounded corners. In this embodiment, the long-side direction of the principal surfaces 11a and 11b coincides with the first direction D1. The direction of the short sides of the main surfaces 11a and 11b coincides with the second direction D2.

The pair of side surfaces 11c extends in the third direction D3 so as to connect the pair of main surfaces 11a and 11b. The pair of side surfaces 11c also extend in the second direction D2. The pair of side surfaces 11e extend in the third direction D3 so as to connect the pair of main surfaces 11a and 11b. The pair of side surfaces 11e also extend in the first direction D1. The length of the piezoelectric body 11 in the first direction D1 is, for example, 20 mm. The length of the piezoelectric body 11 in the second direction D2 is, for example, 10 mm. The length of the piezoelectric body 11 in the third direction D3 is, for example, 0.25 mm. Each main surface 11a, 11b and each side surface 11c, 11e may be indirectly adjacent to each other. In this case, ridges are located between the main surfaces 11a, 11b and the side surfaces 11c, 11e.

In the piezoelectric body 11, as shown in FIGS. 4 and 5, a plurality of piezoelectric layers 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, 18e, and 18f are laminated in the third direction D3. there is The piezoelectric layer 17a has a main surface 11a. The piezoelectric layer 18f has a main surface 11b. The piezoelectric layers 17b, 17c, 17d, 18a, 18b, 18c, 18d, and 18e are located between the piezoelectric layers 17a and 18f. The polarization directions of the piezoelectric layers 17b, 17d, 18b, 18d and 18f are opposite to the polarization directions of the piezoelectric layers 17a, 17c, 18a, 18c and 18e. That is, in the piezoelectric body 11, piezoelectric layers having opposite polarization directions are alternately arranged in the third direction D3. In this embodiment, the piezoelectric layers 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, 18e, and 18f have the same thickness. "Same" includes a range of manufacturing errors.

Each piezoelectric layer 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, 18e, 18f is made of a piezoelectric material. In this embodiment, each piezoelectric layer 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, 18e, 18f is made of a piezoelectric ceramic material. Piezoelectric ceramic materials include, for example, PZT[Pb(Zr,Ti)O3], PT( _PbTiO3 ) _, PLZT[(Pb,La)(Zr,Ti)O3] _, or barium titanate ₍ BaTiO3). is used. Each of the piezoelectric layers 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, 18e, and 18f is composed of, for example, a sintered ceramic green sheet containing the piezoelectric ceramic material described above. In the actual piezoelectric body 11, the piezoelectric layers 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, 18e, and 18f are , 18d, 18e, and 18f are merged to such an extent that they cannot be discerned.

Each external electrode 13, 14, 15 is arranged on the main surface 11a. The external electrodes 13 , 14 , 15 are arranged in the first direction D<b>1 in the order of the external electrode 13 , the external electrode 14 , and the external electrode 15 . The external electrodes 13 and 14 are adjacent to each other in the first direction D1. The external electrodes 14 and 15 are adjacent to each other in the first direction D1. The shortest distance between the external electrodes 14 and 15 is longer than the shortest distance between the external electrodes 13 and 14 in the first direction D1. Each of the external electrodes 13, 14, 15 is separated from all edges (four sides) of the main surface 11a when viewed from the third direction D3.

Each of the external electrodes 13 and 14 has a rectangular shape when viewed from the third direction D3. Rectangular shapes include, for example, shapes with chamfered corners and shapes with rounded corners. In this embodiment, each corner of the rectangular shape is rounded. The external electrode 15 has a square shape when viewed from the third direction D3. The square shape includes, for example, a shape with chamfered corners and a shape with rounded corners. In this embodiment, each corner of the square is rounded. Each external electrode 13, 14, 15 is made of a conductive material. Ag, Pd, Pt, or Ag--Pd alloys, for example, are used for the conductive material. Each of the external electrodes 13, 14, 15 is configured as, for example, a sintered body of a conductive paste containing the conductive material.

The piezoelectric element 3 includes a plurality of internal electrodes 21, 22, 23, 24, 25, 26, 27, 28, and 29 arranged within the piezoelectric body 11, as shown in FIGS. there is Each internal electrode 21, 22, 23, 24, 25, 26, 27, 28, 29 is made of a conductive material. Ag, Pd, Pt, or Ag--Pd alloys, for example, are used for the conductive material. Each of the internal electrodes 21, 22, 23, 24, 25, 26, 27, 28, 29 is, for example, a sintered body of conductive paste containing the conductive material. In this embodiment, the outer shape of each internal electrode 21, 22, 23, 24, 25, 26, 27, 28, 29 is rectangular. Rectangular shapes include, for example, shapes with chamfered corners and shapes with rounded corners.

The respective internal electrodes 21, 22, 23, 24, 25, 26, 27, 28, 29 are arranged at different positions (layers) in the third direction D3. Each of the internal electrodes 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 faces each other with a gap in the third direction D<b>3 . The internal electrodes 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 are not exposed on the surface of the piezoelectric body 11 . That is, the internal electrodes 21, 22, 23, 24, 25, 26, 27, 28 and 29 are not exposed on the side surfaces 11c and 11e. Each of the internal electrodes 21, 22, 23, 24, 25, 26, 27, 28, 29 is separated from all edges (four sides) of the main surfaces 11a, 11b when viewed from the third direction D3.

The internal electrode 21 is positioned between the piezoelectric layers 17a and 17b. The internal electrode 22 is positioned between the piezoelectric layer 17b and the piezoelectric layer 17c. The internal electrode 23 is positioned between the piezoelectric layer 17c and the piezoelectric layer 17d. The internal electrode 24 is positioned between the piezoelectric layer 17d and the piezoelectric layer 18a. The internal electrode 25 is positioned between the piezoelectric layers 18a and 18b. The internal electrode 26 is positioned between the piezoelectric layer 18b and the piezoelectric layer 18c. The internal electrode 27 is positioned between the piezoelectric layer 18c and the piezoelectric layer 18d. The internal electrode 28 is positioned between the piezoelectric layer 18d and the piezoelectric layer 18e. The internal electrode 29 is located between the piezoelectric layer 18e and the piezoelectric layer 18f.

The external electrode 13 is electrically connected to the internal electrode 21 , the internal electrode 23 and the connection conductors 33 through a plurality of via conductors 43 . The plurality of connection conductors 33 are located in the same layers as the internal electrodes 22, 24, 25, 26, 27, 28 and 29, respectively. Specifically, each connection conductor 33 is located in an opening formed in each internal electrode 22 , 24 , 25 , 26 , 27 , 28 , 29 . Each opening is formed at a position corresponding to the external electrode 13 when viewed from the third direction D3. That is, each connection conductor 33 is surrounded by each internal electrode 22, 24, 25, 26, 27, 28, 29 when viewed from the third direction D3. Each connection conductor 33 is separated from each internal electrode 22 , 24 , 25 , 26 , 27 , 28 , 29 .

Each connection conductor 33 faces the external electrode 13 in the third direction D3, and is arranged at a position overlapping the external electrode 13 when viewed from the third direction D3. Each connection conductor 33 faces the internal electrodes 21 and 23 in the third direction D3, and is arranged at a position overlapping the internal electrodes 21 and 23 when viewed from the third direction D3. The plurality of via conductors 43 are respectively positioned between the external electrode 13, the internal electrode 21, the internal electrode 23, and the plurality of connection conductors 33, and are arranged at positions overlapping the external electrodes 13 when viewed from the third direction D3. It is The plurality of via conductors 43 respectively penetrate through the corresponding piezoelectric layers 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, and 18e in the third direction D3.

The external electrode 14 is electrically connected to the internal electrode 25 , the internal electrode 27 , the internal electrode 29 and the connection conductors 34 through a plurality of via conductors 44 . The plurality of connection conductors 34 are located in the same layer as the internal electrodes 21, 22, 23, 24, 26, 28, respectively. Specifically, each connection conductor 34 is positioned in an opening formed in each internal electrode 21 , 22 , 23 , 24 , 26 , 28 . Each opening is formed at a position corresponding to the external electrode 14 when viewed from the third direction D3. That is, each connection conductor 34 is surrounded by each internal electrode 21, 22, 23, 24, 26, 28 when viewed from the third direction D3. Each connection conductor 34 is separated from each internal electrode 21 , 22 , 23 , 24 , 26 , 28 . Each connection conductor 34 is separated from each connection conductor 33 .

The connection conductor 33 and the connection conductor 34 located in the same layer as the internal electrode 22 are located side by side in the same opening. The connection conductor 33 and the connection conductor 34 located in the same layer as the internal electrode 24 are located side by side in the same opening. The connection conductor 33 and the connection conductor 34 located in the same layer as the internal electrode 26 are located adjacent to each other in the same opening. The connection conductor 33 and the connection conductor 34 located in the same layer as the internal electrode 28 are located adjacent to each other in the same opening.

Each connection conductor 34 faces the external electrode 14 in the third direction D3, and is arranged at a position overlapping the external electrode 14 when viewed from the third direction D3. Each connection conductor 34 faces the internal electrodes 25, 27, 29 in the third direction D3, and is arranged at a position overlapping the internal electrodes 25, 27, 29 as viewed from the third direction D3. The plurality of via conductors 44 are positioned between the external electrode 14, the internal electrode 25, the internal electrode 27, the internal electrode 29, and the plurality of connection conductors 34, respectively, and are located between the external electrode 14 and the plurality of connection conductors 34 when viewed from the third direction D3. placed in overlapping positions. The plurality of via conductors 44 respectively penetrate the corresponding piezoelectric layers 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, and 18e in the third direction D3.

The external electrode 15 is electrically connected to the internal electrode 22 , the internal electrode 24 , the internal electrode 26 , the internal electrode 28 and the connection conductors 35 through a plurality of via conductors 45 . The plurality of connection conductors 35 are located in the same layer as the internal electrodes 21, 23, 25, 27, 29, respectively. Specifically, each connection conductor 35 is located in an opening formed in each internal electrode 21 , 23 , 25 , 27 , 29 . Each opening is formed at a position corresponding to the external electrode 15 when viewed from the third direction D3. That is, the entire edge of each connection conductor 35 is surrounded by each internal electrode 21, 23, 25, 27, 29 when viewed from the third direction D3. Each opening is formed at a position corresponding to the external electrode 15 when viewed from the third direction D3.

Each connection conductor 35 faces the external electrode 15 in the third direction D3, and is arranged at a position overlapping the external electrode 15 when viewed from the third direction D3. Each connection conductor 35 faces the internal electrodes 22, 24, 26, and 28 in the third direction D3, and is arranged at a position overlapping the internal electrodes 22, 24, 26, and 28 when viewed from the third direction D3. . The plurality of via conductors 45 are positioned between the external electrode 15, the internal electrode 22, the internal electrode 24, the internal electrode 26, the internal electrode 28, and the plurality of connection conductors 35, respectively, and are It is arranged at a position overlapping with the external electrode 15 . The plurality of via conductors 45 respectively penetrate the corresponding piezoelectric layers 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, and 18e in the third direction D3.

Each connection conductor 33, 34 has a rectangular shape when viewed from the third direction D3. Rectangular shapes include, for example, shapes with chamfered corners and shapes with rounded corners. In this embodiment, each corner of the rectangular shape is rounded. Each connection conductor 35 has a square shape when viewed from the third direction D3. The square shape includes, for example, a shape with chamfered corners and a shape with rounded corners. In this embodiment, each corner of the square is rounded.

The connection conductors 33, 34, 35 and via conductors 43, 44, 45 are made of a conductive material. Ag, Pd, Pt, or Ag--Pd alloys, for example, are used for the conductive material. The connection conductors 33, 34, 35 and the via conductors 43, 44, 45 are configured as, for example, sintered bodies of conductive paste containing the conductive material. Via conductors 43, 44, 45 are conductive conductors filled in through holes formed in ceramic green sheets for forming corresponding piezoelectric layers 17a, 17b, 17c, 17d, 18a, 18b, 18c, 18d, 18e. It is formed by sintering a viscous paste.

A conductor electrically connected to the internal electrodes 21 and 23, a conductor electrically connected to the internal electrodes 25, 27 and 29, and the internal electrodes 22 and 24 are formed on the main surface 11b of the piezoelectric element 11. , 26 and 28 are not arranged. In this embodiment, the main surface 11b is entirely exposed when viewed from the third direction D3. The main surfaces 11a and 11b are natural surfaces. A natural surface is a surface formed by the surfaces of crystal grains grown by firing.

On the side surfaces 11c and 11e of the piezoelectric element 11, conductors electrically connected to the internal electrodes 21 and 23, conductors electrically connected to the internal electrodes 25, 27 and 29, and the internal electrode 22 , 24, 26, 28 are not arranged. In this embodiment, when each side surface 11c is viewed from the second direction D2, each side surface 11c is entirely exposed. When each side surface 11e is viewed from the first direction D1, each side surface 11e is entirely exposed. In this embodiment, the side surfaces 11c and 11e are also natural surfaces.

In the plurality of piezoelectric layers 17b, 17c, 17d, regions sandwiched between internal electrodes 21, 23 connected to the external electrode 13 and internal electrodes 22, 24 connected to the external electrode 15 are piezoelectrically constitutes a first active region 19 that is active in In the plurality of piezoelectric layers 18a, 18b, 18c, 18d and 18e, the piezoelectric layer is sandwiched between the internal electrodes 25, 27 and 29 connected to the external electrode 14 and the internal electrodes 24, 26 and 28 connected to the external electrode 15. The area covered constitutes the piezoelectrically active second active area 20 . The first active region 19 and the second active region 20 are arranged between the main surface 11a and the main surface 11b. The second active region 20 is arranged closer to the main surface 11b than the first active region 19 is. The first active region 19 and the second active region 20 are composed of at least one piezoelectric layer.

In this embodiment, the first active region 19 and the second active region 20 are positioned so as to surround the plurality of external electrodes 13, 14, 15 when viewed from the third direction D3. The first active region 19 and the second active region 20 are a region located between the external electrode 14 and the external electrode 15 as viewed in the third direction D3, and the external electrodes 13, 13 as viewed in the first direction D1. It includes the area outside the area where 14, 15 are located.

In the piezoelectric element 3, in the third direction D3, the pattern P1 is configured in the order of the piezoelectric layer, the internal electrode connected to the external electrode 13, the piezoelectric layer, and the internal electrode connected to the external electrode 15. placed repeatedly. In the piezoelectric element 3, following the pattern P1, in the third direction D3, the piezoelectric layer, the internal electrode connected to the external electrode 14, the piezoelectric layer, and the internal electrode connected to the external electrode 15 are arranged in this order. The pattern P2 is arranged repeatedly.

Operation when an electric field is applied to the first active region 19 and the second active region 20 of the piezoelectric element 3 will be described.

Voltages having different polarities are applied to the external electrodes 13 and 14 . A voltage applied to the external electrodes 13 and 14 is not applied to the external electrode 15 . The external electrode 15 functions as a ground electrode. When the voltage described above is applied to the external electrode 13, an electric field is generated between the internal electrode 21 and the internal electrode 22, between the internal electrode 22 and the internal electrode 23, and between the internal electrode 23 and the internal electrode 24. . When an electric field is generated between the internal electrodes 21, 23 and the internal electrodes 22, 24, the electric field is applied to the first active region 19, and force is generated in the first active region 19 according to the electric field. As a result, the first active region 19 is displaced by a displacement amount corresponding to the force.

When the voltage described above is applied to the external electrode 14, the internal electrode 24 and the internal electrode 25, the internal electrode 25 and the internal electrode 26, the internal electrode 26 and the internal electrode 27, the internal electrode 27 and the internal electrode 27 are applied. An electric field is generated between the electrodes 28 and between the internal electrodes 28 and 29 . When an electric field is generated between the internal electrodes 25, 27, 29 and the internal electrodes 24, 26, 28, the electric field is applied to the second active region 20, and force is generated in the second active region 20 according to the electric field. . As a result, the second active region 20 is displaced by a displacement amount corresponding to the force. At this time, the first active region 19 and the second active region 20 are displaced in opposite directions. Therefore, when a voltage is applied to the external electrodes 13 and 14, the piezoelectric element 3 bends.

In the piezoelectric element 3, when an AC voltage is applied to the external electrodes 13 and 14, the first active region 19 and the second active region 20 repeat expansion and contraction according to the frequency of the applied AC voltage. Therefore, the first active region 19 and the second active region 20 expand and contract in directions opposite to each other, and the piezoelectric element 3 bends and vibrates. The piezoelectric element 3 and diaphragm 5 are joined together. Therefore, in the diaphragm 5 , flexural vibration is generated integrally with the piezoelectric element 3 in response to the flexural vibration of the piezoelectric element 3 .

As shown in FIG. 1, FIG. 2, or FIG. 3, the diaphragm 5 has a main surface (first main surface) 5a and a main surface (second main surface) 5b facing each other. In this embodiment, the diaphragm 5 is a plate-like member. The diaphragm 5 is made of resin. Diaphragm 5 is made of resin containing filler. The filler has a longitudinal direction and may be, for example, glass fiber, carbon fiber, or the like. Diaphragm 5 is made of, for example, liquid crystal polymer (LPC). Each main surface 5a, 5b has a pair of long sides and a pair of short sides. Each principal surface 5a, 5b has a rectangular shape with a pair of long sides and a pair of short sides. That is, the diaphragm 5 has a rectangular shape having a pair of long sides and a pair of short sides in plan view. In this embodiment, the long-side direction of the principal surfaces 5a and 5b coincides with the second direction D2. The direction of the short sides of the main surfaces 5a and 5b coincides with the direction of the first direction D1. The length (thickness) of diaphragm 5 in third direction D3 is, for example, 1.0 mm.

The diaphragm 5 has flexibility. Diaphragm 5 has anisotropic flexibility. The diaphragm 5 has a first bending elastic modulus (Young's modulus) with respect to bending along the first direction D1 and a is different from the second bending elastic modulus with respect to bending along the second direction D2 intersecting with . That is, the diaphragm 5 has a first bending elastic modulus when the diaphragm 5 is bent along the first direction D1 and a second bending elastic modulus when the diaphragm is bent along the second direction D2. different. It can also be said that the bending strength (bending rigidity) of the diaphragm 5 when bent along the first direction D1 differs from the bending strength when the diaphragm 5 is bent along the second direction D2. In this embodiment, the first bending elastic modulus of the diaphragm 5 is higher than the second bending elastic modulus. In other words, in diaphragm 5, the second bending elastic modulus is lower than the first bending elastic modulus. That is, the diaphragm 5 bends (flexes) more easily when bent along the second direction D2 than when bent along the first direction D1. In other words, the diaphragm 5 is less likely to bend when bent along the first direction D1 than when bent along the second direction D2. In the diaphragm 5, the fillers are arranged so that the longitudinal direction thereof is along the second direction D2.

FIG. 6A is a diagram showing the state of the diaphragm 5 when the diaphragm 5 is bent along the first direction D1. FIG. 6(b) is a diagram showing a state of the diaphragm 5 when the diaphragm 5 is bent along the second direction D2. As shown in FIGS. 6A and 6B, the diaphragm 5 is aligned along the first direction D1 when the same force is applied to the diaphragm 5 under the same conditions (temperature, etc.). It bends (bends) more in the case along the second direction D2 than in the case.

As shown in FIG. 2, the joining member 7 joins the piezoelectric element 3 and the diaphragm 5 together. The joining member 7 has, for example, a rectangular shape. The outer shape of the joining member 7 has the same dimensions as the outer shape of the main surface 11 b of the piezoelectric element 3 . The length (thickness) of the joining member 7 in the first direction D1 is, for example, 0.2 mm. The main surface 11b of the piezoelectric element 11 and the main surface 5a of the diaphragm 5 face each other with the joining member 7 interposed therebetween. The joining member 7 is located between the main surface 11b and the main surface 5a. The main surface 11b and the main surface 5a are joined by a joining member 7. As shown in FIG. The joining member 7 is, for example, double-sided tape.

As described above, in the piezoelectric element 3, when an AC voltage is applied to the external electrodes 13 and 14, the first active region 19 and the second active region 20 repeat expansion and contraction according to the frequency of the applied AC voltage. . Therefore, the first active region 19 and the second active region 20 expand and contract in directions opposite to each other, and the piezoelectric element 3 bends and vibrates. In the present embodiment, as shown in FIG. 3, the piezoelectric element 3 that generates such vibrations is arranged such that the longitudinal direction of the piezoelectric element 11 (opposing direction of the pair of side surfaces 11e) is parallel to the second direction D2 of the diaphragm 5 . is arranged on the main surface 5a of the diaphragm 5 along the .

As described above, in the vibration device 1 according to this embodiment, the bending elastic modulus of the diaphragm 5 is different between the first direction D1 and the second direction D2. Therefore, in the vibrating device 1, by changing the arrangement direction (position) of the piezoelectric element 3 with respect to the diaphragm 5, the amplification factor, the amount of displacement, etc. of the diaphragm 5 with respect to the displacement (flexural vibration) of the piezoelectric element 3 change. Therefore, the obtained characteristics (distortion, etc.) are different. Therefore, the vibration device 1 can obtain desired characteristics.

In the vibration device 1 according to this embodiment, the piezoelectric element 11 has a rectangular parallelepiped shape. In diaphragm 5, the first bending elastic modulus is higher than the second bending elastic modulus. That is, the diaphragm 5 is less likely to bend (bend) when bent along the first direction D1 than when bent along the second direction D2. In this configuration, the piezoelectric element 3 is arranged on the diaphragm 5 so that the longitudinal direction of the piezoelectric element 11 is along the second direction D2 when viewed from the third direction D3. In this configuration, by arranging the piezoelectric element 3 on the diaphragm 5 so that the longitudinal direction of the piezoelectric element 11 of the piezoelectric element 3 is along the second direction D2, excessive bending of the diaphragm 5 is suppressed and the piezoelectric element 3 displacement can be transmitted to the diaphragm. As a result, when the vibrating device 1 is an acoustic device, the change in strength of the sound pressure due to the frequency change is suppressed, and the sound quality can be sharp.

In the vibration device 1 according to this embodiment, the vibration plate 5 is made of resin containing filler, and the longitudinal direction of the filler is along the second direction D2. In this configuration, since the bending elastic modulus of the diaphragm 5 differs depending on the orientation direction of the filler, the diaphragm 5 can have different bending elastic moduli in the first direction D1 and the second direction D2.

Although the embodiments of the present invention have been described above, 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 invention.

In the above embodiment, the piezoelectric element 3 is arranged on the vibration plate 5 so that the longitudinal direction of the piezoelectric body 11 is along the second direction D2 when viewed from the third direction D3. However, as shown in FIG. 7, the piezoelectric element 3 may be arranged on the diaphragm 5 such that the longitudinal direction of the piezoelectric element 11 is along the first direction D1 when viewed from the third direction D3. With this configuration, the displacement of the piezoelectric element 3 can be directly transmitted to the diaphragm 5 . As a result, when the vibration device 1 is an acoustic device, the maximum sound pressure can be improved, and the phase shift can be suppressed, thereby suppressing distortion.

In the above embodiment, the piezoelectric element 11 of the piezoelectric element 3 has a rectangular parallelepiped shape as an example. However, as shown in FIG. 8, the piezoelectric element 11A of the piezoelectric element 3A may have a cubic shape. The piezoelectric element 3A is arranged on the diaphragm 5 so that each side of the piezoelectric element 11A extends along the first direction D1 or the second direction D2 when viewed from the third direction D3. With this configuration, the displacement of the piezoelectric element 3 can be directly transmitted to the diaphragm while suppressing excessive bending of the diaphragm 5 . As a result, when the vibration device 1 is an acoustic device, the resonance frequencies are different between the first direction D1 and the second direction D2, so that the peaks of the sound pressure are dispersed, and the change in strength of the sound pressure due to the change in the frequency is suppressed. Moreover, since the phase shift can be suppressed, the distortion can be suppressed.

In the above embodiment, the diaphragm 5 has a first bending elastic modulus (Young's modulus) with respect to bending along the first direction D1 and a second bending elastic modulus with respect to bending along the second direction D2 intersecting the first direction D1. A form with a different rate has been described as an example. However, as shown in FIGS. 9 and 10, the diaphragm 5A has a first flexural elasticity against bending along the first direction (solid arrow direction in FIGS. 9 and 10) when viewed from the third direction D3. and a second bending modulus for bending along a second direction (the dashed arrow direction in FIGS. 9 and 10) intersecting the first direction. In this configuration, the piezoelectric element 3 is arranged on the main surface 5Aa of the diaphragm 5A so that the longitudinal direction of the piezoelectric element 11 intersects the first direction and the second direction when viewed from the third direction D3.

Further, as shown in FIG. 11, the diaphragm 5A has a first bending elastic modulus with respect to bending along the first direction (solid arrow direction in FIG. 11) when viewed from the third direction D3, and a first The second flexural modulus for bending along a second direction (the dashed arrow direction in FIG. 11) that intersects the direction may be different. In this configuration, the piezoelectric element 3A is arranged on the diaphragm 5A so that each side of the piezoelectric element 11A intersects the first direction and the second direction when viewed from the third direction D3.

In the above-described embodiment, an example in which the piezoelectric element 3 is of the bimorph type has been described. However, the piezoelectric element 3 may be, for example, a unimorph type, or may be a piezoelectric element of another mode.

In the above-described embodiment, an example in which the diaphragm 5 is made of a liquid crystal polymer has been described. However, diaphragm 5 may be made of other resin.

In the above-described embodiment, an example in which the diaphragm 5 is made of resin containing filler has been described. However, the diaphragm 5 may have other aspects. For example, diaphragm 5 may be made of wood. Further, the diaphragm 5 may have first members and second members extending along one direction alternately arranged. In this case, the first member and the second member have different hardnesses, and are arranged along the first direction D1 or the second direction D2. Thereby, the diaphragm 5 has a first bending elastic modulus when bent along the first direction D1 and a second bending elastic modulus when bent along the second direction D2.

Reference Signs List 1 Vibration device 3, 3A Piezoelectric element 5, 5A Diaphragm 5a Principal surface (first principal surface) 5b Principal surface (second principal surface) 11, 11A Piezoelectric body 13 , 14, 15...external electrodes, 21, 22, 23, 24, 25, 26, 27, 28, 29...internal electrodes, D1...first direction, D2...second direction.

Claims (7)

a piezoelectric element having an element body, an internal electrode arranged in the element body, and an external electrode connected to the internal electrode;
a flexible vibration plate having first and second main surfaces facing each other and having the piezoelectric element disposed thereon;
The diaphragm has a first bending elastic modulus with respect to bending along the first direction when viewed from the direction in which the first principal surface and the second principal surface face each other, and a second direction intersecting the first direction. A vibrating device that differs from a second flexural modulus for bending along. 2. The vibrating device according to claim 1, wherein the diaphragm is made of resin containing filler, and the longitudinal direction of the filler is along the first direction or the second direction. The element has a rectangular parallelepiped shape,
In the diaphragm, the first bending elastic modulus is higher than the second bending elastic modulus,
3. The vibrating device according to claim 1, wherein said piezoelectric element is arranged on said vibrating plate such that the longitudinal direction of said element extends along said second direction when viewed from said opposing direction. The element has a rectangular parallelepiped shape,
In the diaphragm, the first bending elastic modulus is higher than the second bending elastic modulus,
3. The vibrating device according to claim 1, wherein said piezoelectric element is arranged on said vibrating plate such that the longitudinal direction of said element extends along said first direction when viewed from said facing direction. The element has a cubic shape,
In the diaphragm, the first bending elastic modulus is higher than the second bending elastic modulus,
3. The vibration according to claim 1, wherein the piezoelectric element is arranged on the vibration plate so that each side of the element extends along the first direction or the second direction when viewed from the facing direction. device. The element has a rectangular parallelepiped shape,
In the diaphragm, the first bending elastic modulus is higher than the second bending elastic modulus,
3. The piezoelectric element according to claim 1, wherein the piezoelectric element is arranged on the vibration plate such that the longitudinal direction of the element intersects the first direction and the second direction when viewed from the facing direction. vibration device. The element has a cubic shape,
In the diaphragm, the first bending elastic modulus is higher than the second bending elastic modulus,
3. The piezoelectric element according to claim 1, wherein said piezoelectric element is arranged on said diaphragm so that each side of said element intersects said first direction and said second direction when viewed from said opposing direction. vibration device.

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