JP7279487B2 - Piezoelectric elements, vibration devices and electronic equipment - Google Patents

Description

The present disclosure relates to piezoelectric elements, vibration devices, and electronic equipment.

Patent Literature 1 describes a speaker including a piezoelectric element and a vibrating member.

JP-A-4-70100

When configuring the left speaker and the right speaker using the above-described speakers, it is conceivable to combine the vibration member for the left speaker and the vibration member for the right speaker into one. As a result, the left speaker and the right speaker are integrated, so that miniaturization can be achieved. However, there is a possibility that the vibrations of the piezoelectric elements are mixed in the vibrating member and the sound quality is degraded.

The present disclosure provides a piezoelectric element, a vibration device, and an electronic device capable of suppressing deterioration in sound quality while achieving miniaturization.

A piezoelectric element according to one aspect of the present disclosure includes a piezoelectric body having a first main surface and a second main surface facing each other; a first external electrode and a second external electrode arranged on the piezoelectric body; wherein the piezoelectric body has first and second piezoelectrically active active regions and a piezoelectrically inactive inactive region; and the first external electrode comprises the first active region. A drive signal for driving is input, the second external electrode receives a drive signal for driving the second active region, and the first active region is viewed from the facing direction of the first main surface and the second main surface. The region and the second active region are separated from each other by an inactive region.

The piezoelectric element has a first active area, a second active area, and an inactive area. The first active region is driven by a drive signal input by the first external electrode. The second active region is driven by a drive signal input by the second external electrode. In this way, the first active region and the second active region are configured to be driven by different drive signals, respectively, so that one piezoelectric element can generate two sounds at the same time. Therefore, compared to the case of using two piezoelectric elements that generate one sound, the size of the vibrating device can be reduced. Moreover, the first active region and the second active region are separated from each other through the inactive region. Therefore, the vibrations of the first active region and the second active region are suppressed from being mixed in the piezoelectric body. Also, the inactive region functions as a restraining body that restrains the vibration of the vibrating member. Therefore, it is also suppressed that vibrations by the first active region and the second active region are mixed in the vibrating member. As a result, deterioration of sound quality in the vibrating device can be suppressed.

Viewed from the opposing direction, the area of the first active region and the area of the second active region may be equal to each other. In this case, the magnitudes of sounds generated by the bending vibrations of the first active region and the second active region tend to be the same.

Viewed from the opposing direction, the area of the first active region and the area of the second active region may be different from each other. In this case, the magnitudes of the bending vibrations of the first active region and the second active region are different from each other. Therefore, even when the piezoelectric element is not arranged at the center of the vibrating member, it is possible to bring the magnitudes of the sounds generated by the bending vibrations of the first active region and the second active region to the same level.

A vibrating device according to one aspect of the present disclosure includes a vibrating member having the piezoelectric element, a third main surface joined to the first main surface, and a fourth main surface facing the third main surface, and the vibrating member has a first vibrating portion overlapping with the first active region and a second vibrating portion overlapping with the second active region when viewed from the opposing direction, and the vibrating member has a third main surface and at least one of the fourth principal surface, a groove for separating the first vibrating portion and the second vibrating portion from each other may be provided. In this case, since the vibrating member is provided with the groove, it is further suppressed that the vibrations of the first vibrating portion and the second vibrating portion are mixed with each other. Therefore, the vibration device can further suppress deterioration in sound quality.

The groove may extend through the vibrating member to connect the third and fourth principal surfaces. In this case, since the first vibrating portion and the second vibrating portion are reliably spaced apart from each other, it is possible to suppress mixing of vibrations between the first vibrating portion and the second vibrating portion. Therefore, deterioration of sound quality can be further suppressed.

The vibration device further includes a joining member that joins the first main surface and the third main surface to each other, and the joining member includes a first joining portion that overlaps the first active region when viewed from the opposite direction, and a second active region. and a second joint overlapping the region, wherein the first joint and the second joint may be spaced apart from each other. In this case, since the first joint portion and the second joint portion are separated from each other, the vibration of the first active region is suppressed from being transmitted to the second vibrating portion, and the vibration of the second active region is transmitted to the first vibration. It is suppressed that it is transmitted to the part. Thereby, in the vibrating member, it is further suppressed that the vibrations of the first active region and the second active region are mixed. Therefore, deterioration of sound quality can be further suppressed.

The joint member further has a third joint portion disposed between the first joint portion and the second joint portion when viewed from the opposite direction, the first joint portion and the second joint portion being equal to the third joint portion. It may be harder than In this case, vibrations of the first active region and the second active region are easily transmitted to the first vibrating portion and the second vibrating portion via the first joint portion and the second joint portion.

An electronic device according to one aspect of the present disclosure includes the piezoelectric element or the vibration device.

Since this electronic device includes the piezoelectric element or the vibration device, it is possible to reduce the size of the electronic device while suppressing deterioration in sound quality.

According to one aspect of the present disclosure, there are provided a piezoelectric element, a vibration device, and an electronic device capable of suppressing deterioration in sound quality while achieving miniaturization.

1 is a perspective view showing a vibration device according to an embodiment; FIG. FIG. 2 is an exploded perspective view showing the piezoelectric element of FIG. 1; FIG. 2 is a cross-sectional view along line III-III of FIG. 1; It is a perspective view which shows the vibration device which concerns on a 1st modification. FIG. 5 is an exploded perspective view showing the piezoelectric element of FIG. 4; FIG. 11 is an exploded perspective view showing a piezoelectric element of a vibration device according to a second modified example; It is sectional drawing which expands and shows a part of vibration device which concerns on a 3rd modification. It is sectional drawing which expands and shows a part of vibration device which concerns on a fourth modification.

Hereinafter, embodiments 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 overlapping descriptions are omitted.

FIG. 1 is a perspective view showing a vibration device according to an embodiment. As shown in FIG. 1, a vibrating device 100 according to the embodiment includes a piezoelectric element 1 and a vibrating member 50. As shown in FIG. The vibrating device 100 generates sound by driving the piezoelectric element 1 by applying an AC voltage and vibrating the vibrating member 50 with the piezoelectric element 1 . Vibration device 100 is used, for example, as a speaker or a buzzer. The vibration device 100 is provided, for example, in electronic devices such as televisions and smartphones.

The piezoelectric element 1 has a piezoelectric body 2 and external electrodes 11 , 12 , 13 , 14 , 15 and 16 . The piezoelectric element 1 is a bimorph type piezoelectric element in this embodiment, but may be a unimorph type piezoelectric element. The piezoelectric element 1 is a so-called laminated piezoelectric element.

The piezoelectric element 2 has a rectangular parallelepiped shape. 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 piezoelectric body 2 has main surfaces 2a and 2b facing each other, side surfaces 2c and 2d facing each other, and side surfaces 2e and 2f facing each other. The main surface 2 a faces the vibrating member 50 and is joined to the vibrating member 50 .

Hereinafter, the facing direction of the principal surfaces 2a and 2b is defined as direction D1, the facing direction of side surfaces 2c and 2d is defined as direction D2, and the facing direction of side surfaces 2e and 2f is defined as direction D3. A direction D1 is a direction intersecting (here, perpendicular to) the main surfaces 2a and 2b. A direction D2 is a direction crossing (here, perpendicular to) the side surfaces 2c and 2d. A direction D3 is a direction intersecting (here, perpendicular to) the side surfaces 2e and 2f. The direction D1, the direction D2 and the direction D3 cross each other (orthogonal here).

The main surfaces 2a and 2b are rectangular having a pair of long sides and a pair of short sides. That is, the piezoelectric element 1 (piezoelectric body 2) has a rectangular shape having a pair of long sides and a pair of short sides in plan view. The rectangular shape includes, for example, a shape with chamfered corners and a shape with rounded corners. The long side directions of the main surfaces 2a and 2b match the direction D2. The short side directions of the main surfaces 2a and 2b match the direction D3. The length of the piezoelectric element 2 (the length of the piezoelectric element 2 in the direction D2) is, for example, 60 mm. The width of the piezoelectric element 2 (the length of the piezoelectric element 2 in the direction D3) is, for example, 30 mm. The thickness of the piezoelectric element 2 (the length of the piezoelectric element 2 in the direction D3) is, for example, 0.5 mm. The long side direction of the main surfaces 2a and 2b may match the direction D3, and the short side direction of the main surfaces 2a and 2b may match the direction D2.

2 is an exploded perspective view showing the piezoelectric element of FIG. 1. FIG. FIG. 3 is a cross-sectional view along line III--III in FIG. As shown in FIGS. 2 and 3, the piezoelectric body 2 includes a plurality of (here, 10) piezoelectric layers 20 stacked. The stacking direction of the plurality of piezoelectric layers 20 matches the direction D1. Each piezoelectric layer 20 has, for example, the same shape. Equivalence includes a margin of manufacturing error. The thickness of each piezoelectric layer 20 is, for example, 30 μm.

Each piezoelectric layer 20 has main surfaces 20a and 20b facing each other. Each main surface 20a faces one of the stacking directions. The main surface 20a of the piezoelectric layer 20 arranged at one end in the stacking direction is the main surface 2a. Each main surface 20b faces the other of the stacking directions. The main surface 20b of the piezoelectric layer 20 arranged at the other end in the stacking direction is the main surface 2b.

Each piezoelectric layer 20 is made of a piezoelectric material. In this embodiment, each piezoelectric layer 20 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 piezoelectric layer 20 is composed of, for example, a sintered body of a ceramic green sheet containing the piezoelectric ceramic material described above. In the actual piezoelectric body 2, the piezoelectric layers 20 are integrated to such an extent that the boundaries between the piezoelectric layers 20 cannot be recognized.

As shown in FIG. 1, each external electrode 11, 12, 13, 14, 15, 16 is arranged on the main surface 2b. The external electrodes 11, 12, 13, 14, 15, and 16 are arranged along the short side direction of the main surface 2b at the center of the long side direction of the main surface 2b. The external electrodes 11, 12, 13, 14, 15, and 16 are arranged in this order from the side surface 2e toward the side surface 2f. The external electrodes 11, 12, 13, 14, 15, 16 are separated from each other in the short side direction of the main surface 2b. The external electrodes 11, 12, 13, 14, 15, and 16 are separated from all edges (four sides) of the main surface 2b when viewed in the direction D1.

Each of the external electrodes 11, 12, 13, 14, 15, 16 has, for example, a rectangular shape when viewed from the direction D1. Each of the external electrodes 11, 12, 13, 14, 15, 16 may have a square shape, a circular shape, or the like when viewed from the direction D1. Rectangular and square shapes include, for example, shapes with chamfered corners and shapes with rounded corners. Each external electrode 11, 12, 13, 14, 15, 16 is made of a conductive material. Ag, Pd, Pt, or Ag--Pd alloy is used for the conductive material, for example. Each of the external electrodes 11, 12, 13, 14, 15, 16 is configured as, for example, a sintered body of a conductive paste containing the conductive material.

The external electrodes 11 , 12 , 13 , 14 , 15 and 16 are connected to a control circuit (not shown) that controls the vibration device 100 . The control circuit includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). In this case, the control circuit loads a program stored in the ROM into the RAM and executes various processes by the CPU.

The control circuit inputs drive signals for driving the piezoelectric element 1 to the external electrodes 11 , 12 , 15 and 16 . The control circuit, for example, inputs one of the signal for the left speaker and the signal for the right speaker to the external electrodes 11 and 12 and inputs the other to the external electrodes 15 and 16 as drive signals. The external electrodes 11 and 12 receive a driving signal from a control circuit for driving an active region R1, which will be described later. The external electrodes 15 and 16 receive a drive signal from a control circuit for driving an active region R2, which will be described later. The external electrode 13 is the ground terminal for the active region R1, and the external electrode 14 is the ground terminal for the active region R2.

The external electrodes 11, 12, 13, 14, 15, 16 are connected to the control circuit by wiring members (not shown) such as flexible printed circuit boards (FPC) or flexible flat cables (FFC).

The vibrating member 50 is, for example, a rectangular plate member. The vibrating member 50 has flexibility. The vibrating member 50 is made of resin, glass, or metal, for example. The vibrating member 50 has main surfaces 50a and 50b facing each other. The main surfaces 50a and 50b are rectangular having a pair of long sides and a pair of short sides. The principal surface 50a faces the principal surface 2a and is joined to the piezoelectric element 1 . The piezoelectric element 1 is arranged, for example, in the center of the main surface 50a. The vibrating member 50 is arranged, for example, such that the long side direction of the main surface 50a is aligned with the long side direction of the main surface 2a. The length of the long sides of the main surfaces 50a and 50b is, for example, 200 mm. The length of the short sides of the main surfaces 50a and 50b is, for example, 150 mm. The thickness of the vibrating member 50 is, for example, 1 mm.

As shown in FIGS. 2 and 3, the piezoelectric element 1 includes internal electrodes 31, 32, 33, 34, 35, 36, 37, 38, 41, 42, 43, 44, 45, 46 and through-hole conductors. T1, T2, T3, T4, T5 and T6.

Each internal electrode is arranged on the main surface 20b of each piezoelectric layer 20 arranged other than the other end in the stacking direction. On these main surfaces 20b, the internal electrodes 31, 32, 33, 34, 35, 36 are arranged so as to overlap with the external electrodes 11, 12, 13, 14, 15, 16 when viewed from the stacking direction. The arrangement and shape of the internal electrodes 31, 32, 33, 34, 35, and 36 on the principal surface 20b are, for example, the same as the arrangement and shape of the external electrodes 11, 12, 13, 14, 15, and 16 on the principal surface 2b. I am doing it. The internal electrodes 31, 32, 33, 34, 35, and 36 are arranged in the center of the major surface 20b in the long side direction.

In these main surfaces 20b, an internal electrode 37 is arranged on the side surface 2c side of the internal electrodes 31, 32, 33, 34, 35, and 36, and the side surfaces 2d of the internal electrodes 31, 32, 33, 34, 35, and 36 are arranged. An internal electrode 38 is arranged on the side. The internal electrodes 37 and 38 have, for example, a rectangular shape when viewed from the stacking direction. The internal electrodes 37 and 38 have, for example, the same shape as each other when viewed from the stacking direction, and overlap each other. All edges (four sides) of the internal electrodes 37 and 38 overlap each other, for example, when viewed from the stacking direction. The internal electrodes 37 and 38 are, for example, separated from all edges (four sides) of the main surface 20b when viewed in the stacking direction.

The internal electrode 37 is connected to one of the internal electrodes 31, 32, 33 by the internal electrodes 41, 42, 43, and is separated from the other internal electrodes. The internal electrode 38 is connected to one of the internal electrodes 34 , 35 , 36 by the internal electrodes 44 , 45 , 46 and is separated from the other internal electrodes. The internal electrodes connected to the internal electrodes 37 and 38 differ depending on the lamination position.

Assuming that the piezoelectric layer 20 arranged at one end in the stacking direction is the first piezoelectric layer 20, the internal electrodes 41 are provided on the main surfaces 20b of the second and fourth piezoelectric layers 20. there is The internal electrode 41 is arranged between the internal electrode 37 and the internal electrode 31 and connects the internal electrode 37 and the internal electrode 31 to each other. The internal electrodes 42 are provided on the principal surfaces 20 b of the sixth and eighth piezoelectric layers 20 . The internal electrode 42 is arranged between the internal electrode 37 and the internal electrode 32 and connects the internal electrode 37 and the internal electrode 32 to each other. The internal electrodes 43 are provided on the main surfaces 20b of the first, third, fifth, seventh, and ninth piezoelectric layers 20 . The internal electrode 43 is arranged between the internal electrode 37 and the internal electrode 33 and connects the internal electrode 37 and the internal electrode 33 to each other.

The internal electrodes 44 are provided on the main surfaces 20b of the first, third, fifth, seventh, and ninth piezoelectric layers 20 . The internal electrode 44 is arranged between the internal electrodes 38 and 34 and connects the internal electrodes 38 and 34 to each other. The internal electrodes 45 are provided on the main surfaces 20b of the piezoelectric layers 20 of the second and fourth layers. The internal electrode 45 is arranged between the internal electrodes 38 and 35 and connects the internal electrodes 38 and 35 to each other. The internal electrodes 46 are provided on the principal surfaces 20 b of the sixth and eighth piezoelectric layers 20 . The internal electrode 46 is arranged between the internal electrodes 38 and 36 and connects the internal electrodes 38 and 36 to each other.

Each internal electrode is made of a conductive material. Ag, Pd, Pt, or Ag--Pd alloy is used for the conductive material, for example. Each internal electrode is configured as, for example, a sintered body of a conductive paste containing the conductive material.

Through-hole conductors T1, T2, T3, T4, T5, and T6 are connected to the external electrodes 11, 12, 13, 14, 15, and 16 and the internal They are arranged in through holes (not shown) passing through positions corresponding to the electrodes 31 , 32 , 33 , 34 , 35 and 36 . Through-hole conductors T1, T2, T3, T4, T5 and T6 electrically connect external electrodes 11, 12, 13, 14, 15 and 16 and internal electrodes 31, 32, 33, 34, 35 and 36 to each other. It is

The through-hole conductors T1, T2, T3, T4, T5, T6 contain conductive material. The conductive material is, for example, one or more metals selected from the group consisting of Pd, Ag, Cu, W, Mo, Sn and Ni, or an alloy containing one or more of the above metals. The diameters of the through-hole conductors T1, T2, T3, T4, T5, and T6 are, for example, 20 μm or more and 100 μm or less.

As shown in FIG. 3, the vibrating device 100 includes a joint member 51. As shown in FIG. The joining member 51 joins the piezoelectric element 1 and the vibration member 50 . The joining member 51 includes, for example, a base material made of nonwoven fabric and adhesive layers arranged on both sides of the base material. When the bonding member 51 contains a non-woven fabric, the bonding member 51 can easily follow undulations and small irregularities of the bonding surfaces of the piezoelectric element 1 and the bonding member 51, and the influence of the surface state can be reduced. Vibration can be efficiently transmitted to the vibrating member 50 . When viewed from the stacking direction, the outer edge of the joining member 51 is arranged slightly inside the outer edge of the main surface 20a. As a result, adhesion of foreign matter to the adhesive layer of the joining member 51 is suppressed. The joining member 51 may be, for example, a resin layer made of epoxy resin or acrylic resin. In this case, since the bonding member 51 does not have an adhesive layer, the outer edge of the bonding member 51 may be positioned outside the outer edges of the main surfaces 2a and 2b when viewed from the direction D1.

Next, each region of the piezoelectric body 2 will be described. As shown in FIG. 3, the piezoelectric body 2 has piezoelectrically active active regions R1 and R2 and a piezoelectrically inactive inactive region R3. The active region R1 includes an internal electrode 37 arranged on the main surface 20b of the piezoelectric layer 20 of the first layer (an internal electrode 37 arranged closest to the main surface 2a among the plurality of internal electrodes 37) and a ninth layer. 2 and the internal electrode 37 arranged on the main surface 20b of the piezoelectric layer 20 (the internal electrode 37 arranged closest to the main surface 2b among the plurality of internal electrodes 37). The active region R2 includes an internal electrode 38 arranged on the main surface 20b of the piezoelectric layer 20 of the first layer (the internal electrode 38 arranged closest to the main surface 2a among the plurality of internal electrodes 38) and a ninth layer. This is a region between the internal electrodes 38 arranged on the main surface 20b of the piezoelectric layer 20 (the internal electrode 38 arranged closest to the main surface 2b among the plurality of internal electrodes 38).

The inactive region R3 is a region of the piezoelectric body 2 other than the active regions R1 and R2. More specifically, the inactive regions R3 are regions located between the active regions R1, R2 and the main surfaces 2a, 2b, and between the active regions R1 and R2 when viewed from the direction D1. It includes regions located between R1, R2 and sides 2e, 2f, between active region R1 and side 2c, and between active region R2 and side 2d.

Active regions R1, R2 and inactive region R3 are integrally formed. Active regions R1 and R2 are separated from each other via inactive region R3 when viewed in direction D1. Viewed from direction D1, the area of active region R1 and the area of active region R2 are equal to each other. Here, the volume of the active region R1 and the volume of the active region R2 are also equal to each other.

The active region R1 consists of an active region R11 and an active region R12 stacked in the direction D1. The active region R11 and the active region R12 are arranged side by side in the direction D1. Active region R11 is arranged on the main surface 2a side. Active region R12 is arranged on the main surface 2b side. Specifically, the active region R11 includes an internal electrode 37 arranged on the principal surface 20b of the piezoelectric layer 20 of the first layer and an internal electrode 37 arranged on the principal surface 20b of the piezoelectric layer 20 of the fifth layer. is the area between Specifically, the active region R12 includes the internal electrode 37 arranged on the main surface 20b of the fifth piezoelectric layer 20 and the internal electrode 37 arranged on the main surface 20b of the ninth piezoelectric layer 20. is the area between

The active region R1 is polarized by, for example, applying voltages of different polarities to the external electrodes 11 and 12 while the external electrode 13 is grounded. When the piezoelectric element 1 is driven, voltages of the same polarity are applied to the external electrodes 11 and 12 while the external electrode 13 is grounded. As a result, one of the active regions R11 and R12 is applied with a voltage in the same direction (forward direction) as the polarization direction and elongated, and the other is applied with a voltage in the opposite direction (reverse direction) to the polarization direction. and contract. As a result, the active region R1 undergoes bending vibration in the stacking direction.

The active region R2 consists of an active region R21 and an active region R22 stacked in the direction D1. The active region R21 and the active region R22 are arranged side by side in the direction D1. Active region R21 is arranged on the main surface 2a side. Active region R22 is arranged on the main surface 2b side. Specifically, the active region R21 includes the internal electrode 38 arranged on the main surface 20b of the piezoelectric layer 20 of the first layer and the internal electrode 38 arranged on the main surface 20b of the piezoelectric layer 20 of the fifth layer. is the area between Specifically, the active region R22 includes an internal electrode 38 arranged on the main surface 20b of the fifth piezoelectric layer 20 and an internal electrode 38 arranged on the main surface 20b of the ninth piezoelectric layer 20. is the area between

The active region R2 is polarized by, for example, applying voltages of different polarities to the external electrodes 15 and 16 while the external electrode 14 is grounded. When the piezoelectric element 1 is driven, voltages of the same polarity are applied to the external electrodes 15 and 16 while the external electrode 14 is grounded. As a result, one of the active regions R21 and R22 is applied with a voltage in the same direction (forward direction) as the polarization direction and elongated, and the other is applied with a voltage in the opposite direction (reverse direction) to the polarization direction. and contract. As a result, the active region R2 undergoes bending vibration in the stacking direction.

The vibrating member 50 thus flexures and vibrates along with the flexural vibration of the active regions R1 and R2, thereby generating sound. The vibration member 50 generates a sound due to bending vibration of the active region R1 and a sound due to bending vibration of the active region R2. As described above, when signals for the left speaker are input to the external electrodes 11 and 12 and signals for the right speaker are input to the external electrodes 15 and 16, the vibrating member 50 produces sound for the left speaker and sound for the right speaker. to generate both sounds.

As described above, the piezoelectric element 1 has the active regions R1, R2 and the inactive region R3. The active region R1 is driven by drive signals input to the external electrodes 11 and 12. FIG. The active region R2 is driven by drive signals input to the external electrodes 15 and 16. FIG. In this way, the piezoelectric element 1 is configured such that the active regions R1 and R2 can be driven by different drive signals. Therefore, in the vibrating device 100, one piezoelectric element 1 can generate two sounds at the same time. Therefore, the vibration device 100 can be made smaller than a vibration device having two piezoelectric elements that generate one sound.

In the piezoelectric element 1, the active regions R1 and R2 are separated from each other via the inactive region R3. Therefore, mixing of vibrations of the active regions R1 and R2 in the piezoelectric body 2 is suppressed. In addition, the inactive region R3 functions as a restraining body that restrains the vibrating member 50. As shown in FIG. Therefore, it is also suppressed that the vibrations of the active regions R1 and R2 are mixed in the vibrating member 50 . As a result, deterioration of sound quality in the vibration device 100 can be suppressed. Through-hole conductors T1, T2, T3, T4, T5 and T6 are provided in the inactive region R3. The space of the piezoelectric body 2 can be effectively utilized compared to the case where it is provided in the area.

In the piezoelectric element 1, the active regions R1 and R2 have the same area when viewed from the direction D1. Therefore, the magnitudes of sounds generated by the bending vibrations of the active regions R1 and R2 tend to be the same. Therefore, even when the active region R1 is driven by the signal for the left speaker and the active region R2 is driven by the signal for the right speaker, the sound for the left speaker and the sound for the right speaker are output in good balance.

In the piezoelectric element 1, the external electrodes 11, 12, 13, 14, 15, and 16 are collectively arranged in the center of the main surface 2b, so that the external electrodes 11, 12, 13, 14, 15, 11, 12, 13, 14, 15, 15, 15, 15, 15, 15, 16, 16, 16, 18, 18, 18, 18, 19, 19, 16 and the control circuit can be easily connected. Therefore, the wiring member can be easily attached to the piezoelectric element 1 .

(first modification)
FIG. 4 is a perspective view showing a vibration device according to a first modification. 5 is an exploded perspective view showing the piezoelectric element of FIG. 4. FIG. As shown in FIGS. 4 and 5, the vibration device 100A according to the first modification differs from the vibration device 100 (see FIG. 1) in that it includes a piezoelectric element 1A instead of the piezoelectric element 1 (see FIG. 1). are different. The piezoelectric element 1</b>A will be described below, focusing on the differences from the piezoelectric element 1 .

The piezoelectric element 1A does not have the external electrodes 14 (see FIG. 1). In the piezoelectric element 1A, the external electrode 13 is also used as a ground terminal for the active regions R1 and R2. In the piezoelectric element 1A, each external electrode 11, 12, 13, 15, 16 is continuously provided on the main surface 2b and the side surface 2e. That is, each of the external electrodes 11, 12, 13, 15, and 16 has a main surface electrode portion provided on the main surface 2b and a side surface electrode portion provided on the side surface 2e. The main surface electrode portions and the side surface electrode portions of each of the external electrodes 11, 12, 13, 15 and 16 are integrally formed with each other.

The external electrodes 11, 12, 13, 15, and 16 are arranged at the center of the main surface 2b in the long side direction on the main surface 2b and the side surface 2e. The external electrodes 11, 12, 13, 15, 16 are separated from each other in the long side direction of the main surface 2b. The external electrodes 11, 12, 13, 15, 16 are arranged along the long side direction of the main surface 2b. The external electrodes 11, 12, 13, 15, and 16 are arranged in this order from the side surface 2c toward the side surface 2d. The side electrode portions of the external electrodes 11, 12, 13, 15, and 16 extend from the edge of the side surface 2e on the main surface 2a side to the edge on the main surface 2b side. It is connected to the main surface electrode part. Principal surface electrode portions of the external electrodes 11, 12, 13, 15, and 16 are arranged at the edge of the principal surface 2b on the side surface 2e side.

The piezoelectric element 1A does not have the internal electrodes 31, 32, 33, 34, 35, 36, 44 and the through-hole conductors T1, T2, T3, T4, T5, T6 shown in FIG. The piezoelectric element 1A has an internal electrode 39 in addition to the internal electrodes 37 and 38 . The internal electrode 39 is made of the same conductive material as the internal electrodes 37 and 38, for example.

The internal electrode 37 is connected to one of the side electrode portions of the external electrodes 11, 12, and 13 by the internal electrodes 41, 42, and 43, and is separated from the other side electrode portions. The internal electrode 38 is connected to the side electrode portions of the external electrodes 13, 15 and 16 by the internal electrodes 43, 45 and 46, and is separated from the other side electrode portions. The internal electrodes 41, 42, 43, 45, 46 connected to the internal electrodes 37, 38 are different depending on the lamination position.

The internal electrodes 39 are provided between the internal electrodes 37 and 38 on the main surfaces 20b of the first, third, fifth, seventh, and ninth piezoelectric layers 20, and The electrode 37 and the internal electrode 38 are connected. The internal electrode 39 is provided on the side surface 2e of the main surface 20b. The internal electrode 39 is separated from the side surface 2e when viewed in the stacking direction.

The internal electrodes 41, 42, 43, 45, 46 are arranged so as to overlap with the external electrodes 11, 12, 13, 15, 16 as viewed in the direction D3. In this embodiment, the internal electrodes 41, 42, 43, 45, 46 are exposed on the side surface 2e. In the piezoelectric element 1A, similarly to the piezoelectric element 1 (see FIG. 2), the internal electrodes 41 and 45 are provided on the main surfaces 20b of the second and fourth piezoelectric layers 20, and the internal electrodes 42 and 46 are provided on the main surfaces 20b of the sixth and eighth piezoelectric layers 20, and the internal electrodes 43 and 44 are provided on the first, third, fifth, seventh and ninth piezoelectric layers It is provided on the major surface 20 b of the layer 20 .

The internal electrode 41 is arranged between the internal electrode 37 and the side electrode portion of the external electrode 11 and connects the internal electrode 37 and the side electrode portion of the external electrode 11 to each other. The internal electrode 42 is arranged between the internal electrode 37 and the side electrode portion of the external electrode 12 and connects the internal electrode 37 and the side electrode portion of the external electrode 12 to each other. The internal electrode 43 is arranged between the internal electrode 39 and the side electrode portion of the external electrode 13 and connects the internal electrode 39 and the side electrode portion of the external electrode 13 to each other. Thereby, the internal electrodes 37 and 38 are electrically connected to the external electrode 13 . The internal electrode 45 is arranged between the internal electrode 38 and the side electrode portion of the external electrode 15 and connects the side electrode portions of the internal electrode 38 and the external electrode 15 to each other. The internal electrode 46 is arranged between the internal electrode 38 and the side electrode portion of the external electrode 16 and connects the side electrode portions of the internal electrode 38 and the external electrode 16 to each other.

In the piezoelectric element 1A, the active region R1 is driven by drive signals input by the external electrodes 11 and 12. As shown in FIG. The active region R2 is driven by drive signals input to the external electrodes 15 and 16. FIG. Thus, in the piezoelectric element 1A as well, the active regions R1 and R2 are configured to be driven by different drive signals. Therefore, in the vibrating device 100A as well, one piezoelectric element 1A can generate two sounds at the same time. Therefore, the vibration device 100A can be made smaller than a vibration device having two piezoelectric elements that generate one sound. Also in the piezoelectric element 1A, the active regions R1 and R2 are separated from each other with the inactive region R3 (see FIG. 3) interposed therebetween. Therefore, deterioration of sound quality in the vibration device 100A can be suppressed. Furthermore, in the piezoelectric element 1A as well, the active regions R1 and R2 have the same area when viewed from the direction D1. Therefore, in the vibrating device 100A, the magnitudes of sounds generated by the bending vibrations of the active regions R1 and R2 tend to be the same.

(Second modification)
FIG. 6 is an exploded perspective view showing a piezoelectric element of a vibration device according to a second modified example. A vibration device 100B according to the second modification shown in FIG. 6 is different from the vibration device 100 (see FIG. 1) in that it includes a piezoelectric element 1B instead of the piezoelectric element 1 (see FIG. 1). The piezoelectric element 1B will be described below, focusing on the differences from the piezoelectric element 1. FIG.

The piezoelectric element 1B does not have the external electrode 14, internal electrode 34 and through-hole conductor T4 shown in FIG. In the piezoelectric element 1B, the external electrode 13 is also used as a ground terminal for the active regions R1 and R2. In the piezoelectric element 1B, the external electrodes 11, 12, 13, 15, and 16 are provided closer to the side surface 2d (see FIG. 1) than the longitudinal center of the main surface 2b. Accordingly, the internal electrodes 37 and 38 have different shapes and areas when viewed from the stacking direction. The area of the internal electrode 37 is larger than the area of the internal electrode 38 when viewed from the stacking direction. Therefore, the areas of the active regions R1 and R2 are different from each other when viewed from the direction D1. The area of active region R1 is larger than the area of active region R2.

The internal electrode 37 is connected to one of the internal electrodes 31, 32, 33 by the internal electrodes 41, 42, 43, and is separated from the other internal electrodes. The internal electrode 38 is connected to one of the internal electrodes 33, 35, 36 by internal electrodes 44, 45, 46, and is separated from the other internal electrodes. The internal electrodes connected to the internal electrodes 37 and 38 differ depending on the lamination position.

In the piezoelectric element 1B, similarly to the piezoelectric element 1 (see FIG. 2), the internal electrodes 41 and 45 are provided on the main surfaces 20b of the second and fourth piezoelectric layers 20, and the internal electrodes 42 and 46 are provided on the main surfaces 20b of the sixth and eighth piezoelectric layers 20, and the internal electrodes 43 and 44 are provided on the first, third, fifth, seventh and ninth piezoelectric layers It is provided on the major surface 20 b of the layer 20 . In the piezoelectric element 1B, the internal electrode 44 is arranged between the internal electrode 38 and the internal electrode 33 and connects the internal electrode 38 and the internal electrode 33 to each other. Therefore, the internal electrodes 37, 38 are connected to each other by the internal electrodes 33, 43, 44 on the main surfaces 20b of the first, third, fifth, seventh, and ninth piezoelectric layers 20. ing.

In the piezoelectric element 1B, the active region R1 is driven by drive signals input by the external electrodes 12 and 13. As shown in FIG. The active region R2 is driven by drive signals input to the external electrodes 15 and 16. FIG. Thus, in the piezoelectric element 1B as well, the active regions R1 and R2 are configured to be driven by different drive signals. Therefore, in the vibrating device 100B as well, one piezoelectric element 1B can generate two sounds at the same time. Therefore, the vibration device 100B can be made smaller than a vibration device having two piezoelectric elements that generate one sound. Also in the piezoelectric element 1B, the active regions R1 and R2 are separated from each other via the inactive region R3 (see FIG. 3). Therefore, deterioration of sound quality in the vibration device 100B can be suppressed.

In the piezoelectric element 1B, the active regions R1 and R2 have different areas when viewed from the direction D1. Therefore, the magnitudes of bending vibrations caused by the active regions R1 and R2 are different from each other. Therefore, even when the piezoelectric element 1 is not arranged at the center of the main surface 50a, the magnitudes of the sounds generated by the bending vibrations of the active regions R1 and R2 can be brought close to each other. For example, even if the piezoelectric element 1 cannot be placed in the center of the main surface 50a, the active regions R1 and R2 can be set so that the sound volume balance is maintained.

(Third modification)
FIG. 7 is a cross-sectional view showing an enlarged part of the vibration device according to the third modification. As shown in FIG. 7, a vibration device 100C according to the third modification includes a vibration member 50C instead of the vibration member 50 (see FIG. 3), and a joint member 51 (see FIG. 3) instead of the joint member 51C is provided, which is different from the vibration device 100 (see FIG. 3). In the following, the vibration member 50C and the joint member 51C will be described, focusing on the differences from the vibration member 50 and the joint member 51. As shown in FIG.

The vibrating member 50C has vibrating portions V1 and V2. The vibrating portion V1 overlaps the active region R1 when viewed in the direction D1. The vibrating portion V2 overlaps the active region R2 when viewed from the direction D1. The vibrating member 50C is provided with a groove 50c that separates the vibrating portions V1 and V2 from each other on at least one of the main surfaces 50a and 50b. In this embodiment, two grooves 50c are provided in the main surface 50a. Each groove 50c extends along the short side direction of the main surface 2b and is provided continuously from one end to the other end of the main surface 50a in the short side direction of the main surface 2b. As viewed in direction D1, two trenches 50c are arranged between active region R1 and active region R2 and are spaced apart from each other in the long side direction of main surface 2b.

The joint member 51C has joint portions 51a, 51b, and 51c that are spaced apart from each other. The junction portion 51a overlaps the active region R1 when viewed in the direction D1. The junction 51b overlaps the active region R2 when viewed in the direction D1. The joints 51a and 51b do not overlap the groove 50c when viewed from the direction D1. The joint portion 51c is arranged between the joint portion 51a and the joint portion 51b when viewed from the direction D1. The junction portion 51c overlaps a region of the inactive region R3 between the active region R1 and the active region R2 when viewed in the direction D1. The joint portion 51c is arranged between the two grooves 50c and does not overlap with the two grooves 50c when viewed in the direction D1.

The joints 51a and 51b are harder than the joint 51c.

A vibration device 100C includes a piezoelectric element 1 . Therefore, the size of the vibrating device 100C can also be reduced. Also, deterioration of sound quality can be suppressed. Furthermore, the magnitudes of sounds generated by the bending vibrations of the active regions R1 and R2 tend to be the same.

The vibrating member 50C has a vibrating portion V1 overlapping with the active region R1 and a vibrating portion V2 overlapping with the active region R2. The vibrating member 50C is provided with a groove 50c that separates the vibrating portions V1 and V2 from each other on the main surface 50a. The presence of the groove 50c in this way further suppresses mixing of the vibrations of the vibrating portion V1, which vibrates due to the vibration of the active region R1, and the vibrating portion V2, which vibrates due to the vibration of the active region R2. . Therefore, the vibration device 100C can further suppress deterioration in sound quality. Moreover, since the two grooves 50c are provided in the vibration member 50C, deterioration of sound quality can be further suppressed as compared with the case where one groove 50c is provided.

The joining member 51C has a joining portion 51a overlapping with the active region R1 and a joining portion 51b overlapping with the active region R2. Since the joint portions 51a and 51b are spaced apart from each other, transmission of the vibration of the active region R1 to the vibrating portion V2 is suppressed, and transmission of the vibration of the active region R2 to the vibrating portion V1 is suppressed. As a result, in the vibrating member 50C, it is further suppressed that the vibrations of the active regions R1 and R2 are mixed. Therefore, the vibration device 100C can further suppress deterioration in sound quality.

The joints 51a and 51b are harder than the joint 51c. Vibrations are transmitted more easily as the joints are harder. Therefore, vibrations of the active regions R1 and R2 are easily transmitted to the vibrating portions V1 and V2 via the joint portions 51a and 51b.

(Fourth modification)
FIG. 8 is a cross-sectional view showing an enlarged part of a vibration device according to a fourth modification. As shown in FIG. 8, a vibration device 100D according to the fourth modification includes a vibration member 50D instead of the vibration member 50 (see FIG. 3), and a joint member 51 (see FIG. 3) instead of the joint member 51D, which is different from the vibration device 100 (see FIG. 3). Since the joint member 51D has the same configuration as the joint member 51C (see FIG. 7), the description thereof is omitted. The vibrating member 50D differs from the vibrating member 50C in that the groove 50c penetrates the vibrating member 50C so as to connect the main surface 50a and the main surface 50b. have. In the vibrating device 100D, the vibrating portions V1 and V2 are reliably separated from each other by the groove 50c, so that the vibrations of the vibrating portions V1 and V2 are further suppressed from being mixed with each other. Therefore, deterioration of sound quality can be further suppressed. Since the vibrating device 100D includes the piezoelectric element 1D, it is possible to suppress deterioration in sound quality while achieving miniaturization.

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

For example, in the piezoelectric elements 1, 1A, 1C and 1D, the active regions R1 and R2 may have different areas when viewed in the direction D1. Also, in the piezoelectric element 1B, the active regions R1 and R2 may have the same area when viewed from the direction D1.

Although two grooves 50c are provided in vibration devices 100C and 100D, one groove 50c may be provided, or three or more grooves 50c may be provided. In the vibration device 100C, the grooves 50c are provided only on the main surface 50a, but may be provided on the main surface 50b. The groove 50c may be provided in each of the main surfaces 50a and 50b. In this case, compared to the case where the groove 50c is provided only on the main surface 50a or only on the main surface 50b, mixing of the vibrations of the vibrating portion V1 and the vibrating portion V2 is further suppressed. Therefore, deterioration of sound quality can be further suppressed.

In the vibration devices 100C and 100D, the groove 50c is provided continuously from one end to the other end of the main surface 50a in the short side direction of the main surface 2b. may be provided in the department. The grooves 50c may be intermittently provided along the short side direction of the main surface 2b.

In the vibration devices 100C and 100D, the hardness of the joints 51a and 51b may be the same as the hardness of the joint 51c. In this case, the joints 51a, 51b, 51c can be easily formed from the same material. In the vibration devices 100C, 100D, the joints 51a, 51b, 51c do not have to be separated from each other.

Vibration devices 100, 100A and 100B may include vibration members 50C and 50D instead of vibration member 50. FIG. The vibration devices 100, 100A, and 100B may include a joint member 51C instead of the joint member 51. FIG. In the vibration devices 100C and 100D, instead of the piezoelectric element 1, piezoelectric elements 1A and 1B may be provided.

The piezoelectric element 1A may have an external electrode 14, the external electrode 13 may be used as a ground terminal for the active region R1, and the external electrode 14 may be used as a ground terminal for the active region R2. In this case, the piezoelectric element 1A does not have the internal electrode 39, the internal electrode 43 is arranged between the internal electrode 37 and the side electrode portion of the external electrode 13, and the side electrode portion of the internal electrode 37 and the external electrode 13 is arranged. to each other. In addition, the piezoelectric element 1A has an internal electrode 44. The internal electrode 44 is arranged between the internal electrode 38 and the side electrode portion of the external electrode 14, and the side electrode portions of the internal electrode 38 and the external electrode 14 are connected to each other. Connecting.

1, 1A, 1B, 1C, 1D... Piezoelectric element, 2... Piezoelectric body, 2a... Main surface (first main surface), 2b... Main surface (second main surface), 11, 12... External electrode (first external electrode), 15, 16... external electrode (second external electrode), 50, 50C, 50D... vibration member, 50a... main surface (third main surface), 50b... main surface (fourth main surface), 50c... Grooves 51, 51C, 51D... Joining member, 51a... Joining part (first joining part), 51b... Joining part (second joining part), 51c... Joining part (third joining part), 100, 100A, 100B, 100C, 100D... vibration device, R1... active region (first active region), R2... active region (second active region), R3... inactive region.

Claims (11)

a piezoelectric body having a first main surface and a second main surface facing each other;
a first external electrode and a second external electrode disposed on the piezoelectric body,
the piezoelectric body has first and second piezoelectrically active active regions and a piezoelectrically inactive inactive region;
the first external electrode receives a drive signal for driving the first active region;
the second external electrode receives a drive signal for driving the second active region;
When viewed from the facing direction of the first main surface and the second main surface, the first active region and the second active region are separated from each other via the inactive region provided with a through-hole conductor. ,Piezoelectric element. a piezoelectric body having a first main surface and a second main surface facing each other;
a first external electrode and a second external electrode disposed on the piezoelectric body,
the piezoelectric body has first and second piezoelectrically active active regions and a piezoelectrically inactive inactive region;
the first external electrode receives a drive signal for driving the first active region;
the second external electrode receives a drive signal for driving the second active region;
The first active region and the second active region are separated from each other via the inactive region when viewed from the facing direction of the first main surface and the second main surface,
The inactive region includes a portion of the first main surface facing the first active region, a portion of the first main surface facing the second active region, and a portion of the second main surface facing the first active region. A piezoelectric element , comprising: a portion facing an active region; and a portion of the second main surface facing the second active region . 3. The piezoelectric element according to claim 1 , wherein an area of said first active region and an area of said second active region are equal to each other when viewed from said opposing direction. 3. The piezoelectric element according to claim 1, wherein the area of the first active region and the area of the second active region are different from each other when viewed from the opposing direction. The piezoelectric element according to any one of claims 1 to 4, wherein the piezoelectric body includes a plurality of piezoelectric layers laminated in the facing direction. a first internal electrode electrically connected to the first external electrode;
The piezoelectric element according to any one of claims 1 to 5, further comprising a second internal electrode electrically connected to said second external electrode. a piezoelectric element comprising a piezoelectric element having a first main surface and a second main surface facing each other; and a first external electrode and a second external electrode arranged on the piezoelectric element;
a vibration member having a third main surface joined to the first main surface and a fourth main surface facing the third main surface;
the piezoelectric body has first and second piezoelectrically active active regions and a piezoelectrically inactive inactive region;
the first external electrode receives a drive signal for driving the first active region;
the second external electrode receives a drive signal for driving the second active region;
The first active region and the second active region are separated from each other via the inactive region when viewed from the facing direction of the first main surface and the second main surface,
The vibrating member has a first vibrating portion that overlaps with the first active region and a second vibrating portion that overlaps with the second active region when viewed from the opposing direction,
The vibrating device according to claim 1, wherein the vibrating member is provided with a groove that separates the first vibrating portion and the second vibrating portion from each other on at least one of the third main surface and the fourth main surface. 8. The vibration device according to claim 7 , wherein said groove penetrates said vibration member so as to connect said third principal surface and said fourth principal surface. further comprising a joining member that joins the first main surface and the third main surface to each other;
the joining member has a first joining portion that overlaps with the first active region and a second joining portion that overlaps with the second active region when viewed from the facing direction;
9. The vibrating device according to claim 7 or 8 , wherein said first joint and said second joint are spaced apart from each other. The joint member further has a third joint portion disposed between the first joint portion and the second joint portion when viewed from the facing direction,
10. The vibration device according to claim 9 , wherein said first joint and said second joint are harder than said third joint. An electronic device comprising the piezoelectric element according to any one of claims 1 to 6 or the vibrating device according to any one of claims 7 to 10 .

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