JP2022109645A - vibration device - Google Patents

Abstract

To provide a vibration device of which the output distortion with respect to frequency can be remedied and of which the sound pressure can be consequently improved.SOLUTION: A vibrating device 1 comprises: a piezoelectric element 4; a vibration portion 5 to which the piezoelectric element 4 is fixed and causes bending vibration by driving the piezoelectric element 4; a base portion 11 arranged opposite to the vibration portion 5; and a support portion 12 fixed to at least one end portion 5c in the vibration portion 5 and the base portion 11 and supporting the vibration portion 5 at a fixed interval with respect to the base portion 11. The support portion 12 is constituted to be deformable following bending vibration.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to vibration devices.

As a conventional vibration device, for example, there is a transparent speaker described in Patent Document 1. This conventional vibrating device is constructed by fixing a piezoelectric element to a vibrating portion. In this vibrating device, a desired acoustic output is obtained by amplifying the vibration of the piezoelectric element by the vibrating portion and causing bending vibration in the vibrating portion.

JP-A-4-70100

Like the vibrating device of Patent Literature 1 described above, the configuration using the bending vibration of the vibrating portion is excellent in vibration transmissibility from the piezoelectric element to the vibrating portion. On the other hand, bending vibration is likely to cause output distortion with respect to frequency, and the reduction in sound pressure caused by the output distortion has been a problem to be solved.

The present disclosure has been made to solve the above problems, and an object thereof is to provide a vibrating device capable of improving output distortion with respect to frequency and improving sound pressure.

A vibrating device according to one aspect of the present disclosure includes a piezoelectric element, a vibrating section to which the piezoelectric element is fixed and which generates bending vibration by driving the piezoelectric element, a base section arranged opposite to the vibrating section, and at least the vibrating section. a supporting portion fixed to the one end portion and the base portion and supporting the vibrating portion at a constant distance from the base portion, wherein the supporting portion is configured to be deformable following the bending vibration. .

In this vibrating device, the vibrating portion is supported with respect to the base portion by the supporting portion. When the piezoelectric element is driven to generate bending vibration in the vibrating portion, the support portion deforms following the bending vibration. Therefore, the ends of the vibrating portion are easily displaced during bending vibration, and the application of reaction force from the support portion to the vibrating portion is suppressed. As a result, the output distortion with respect to frequency can be improved, and the sound pressure can be improved.

The supporting portion may be plate-shaped and fixed to the entire end portion of the vibrating portion. In this case, the entire one end of the vibrating portion is firmly supported by the supporting portion, and bending vibration in the direction along the end is suppressed. Therefore, in the bending vibration, it becomes easy to extract only the necessary vibration mode, and the output distortion with respect to the frequency can be further improved.

The vibrating portion may extend in one direction, and the support portions may be fixed to both ends of the vibrating portion in one direction and to the base portion. In this case, both ends of the vibrating portion in one direction are firmly supported by the supporting portions, and bending vibration in the direction orthogonal to the one direction is suppressed. Therefore, it becomes easy to extract only the vibration mode of the bending vibration in one direction, and the output distortion with respect to frequency can be further improved.

The support portion may have an inclined portion that inclines toward the central portion side in one direction from the base portion side toward the vibrating portion side. In this case, it is possible to further enhance the followability of the support portion toward the central portion in one direction.

The support may be provided with constrictions or slits. In this case, the flexural rigidity of the supporting portion can be easily reduced, and the followability of the supporting portion to bending vibration can be further enhanced.

The bending rigidity of the supporting portion may be equal to or less than that of the vibrating portion. As a result, it is possible to further improve the followability of the support portion to the bending vibration.

The bending rigidity of the base portion may be equal to or greater than that of the vibrating portion. Thereby, the stability of the base portion can be secured.

According to the present disclosure, it is possible to improve the output distortion with respect to frequency and improve the sound pressure.

1 is a schematic plan view showing the configuration of a vibration device according to a first embodiment; FIG. FIG. 2 is a sectional view taken along the line II-II in FIG. 1; FIG. 4 is an enlarged cross-sectional view of a main part showing a fixing structure between a vibrating portion and a supporting portion; It is a schematic sectional drawing which shows the effect|action of a support part. FIG. 5 is a schematic cross-sectional view showing the configuration of a vibrating device according to a second embodiment; 4(a) to 4(c) are enlarged cross-sectional views of main parts showing another example of a structure for fixing the vibrating portion and the supporting portion; FIG. (a) to (c) are schematic side views showing another example of the support portion.

Hereinafter, preferred embodiments of a vibrating device according to one aspect of the present disclosure will be described in detail with reference to the drawings.
[First embodiment]

FIG. 1 is a schematic plan view showing the configuration of the vibration device according to the first embodiment. FIG. FIG. 2 is a sectional view taken along line II-II in FIG. A vibrating device 1 shown in FIGS. 1 and 2 is a device used as an acoustic device such as a speaker, for example, and can be mounted on an electronic device that emits sound, such as a television or a smartphone. As shown in FIGS. 1 and 2, the vibration device 1 includes a piezoelectric vibrator 2, a base portion 11, and a support portion 12. As shown in FIG.

The piezoelectric vibrator 2 includes a piezoelectric element 4 and a vibrating portion 5 . The piezoelectric element 4 has, for example, a piezoelectric body and a pair of external electrodes (not shown). The piezoelectric body is configured by laminating a plurality of piezoelectric layers. In the examples of FIGS. 1 and 2, the piezoelectric element has a rectangular shape in plan view. Each piezoelectric layer is made of a piezoelectric material. In this embodiment, each piezoelectric layer is made of a piezoelectric ceramic material. Examples of piezoelectric ceramic materials include PZT[Pb(Zr, Ti)O3], PT( _PbTiO3 ) _, PLZT[(Pb, La)(Zr, Ti)O3] _, and barium titanate ₍ BaTiO3). be done.

Each piezoelectric layer is composed of, for example, a sintered body of a ceramic green sheet containing the piezoelectric ceramic material described above. In an actual piezoelectric body, each piezoelectric layer is integrated to such an extent that the boundary between each piezoelectric layer cannot be recognized. A plurality of internal electrodes (not shown) are arranged in the piezoelectric body. Each internal electrode is made of a conductive material. Examples of conductive materials include Ag, Pd, and Ag--Pd alloys.

A wiring member (not shown) such as a flexible printed circuit board is electrically connected to the pair of external electrodes of the piezoelectric element 4 . One end side of the wiring member is electrically and physically connected to a pair of external electrodes of the piezoelectric element 4, and the other end side of the wiring member is electrically and physically connected to an electronic device on which the vibrating device 1 is mounted. connected to

The vibrating portion 5 is a portion that generates bending vibration by driving the piezoelectric element 4 . The vibrating portion 5 is made of, for example, a metal material in the form of a thin plate, and extends in one direction with a constant width. Hereinafter, one direction in which the vibrating portion 5 extends will be referred to as an extension direction D. As shown in FIG. A direction orthogonal to one direction is called a width direction W. As shown in FIG. Examples of metal materials include Ni—Fe alloys, Ni, brass, and stainless steel. The vibrating section 5 may be made of a resin material. Examples of resin materials include polycarbonate (PC) and polyphenylene sulfide (PPS). Here, the vibrating portion 5 has a rectangular shape in plan view, and has long sides along the extending direction D and short sides perpendicular to the extending direction D. As shown in FIG. Rectangular shapes may also include, for example, shapes with chamfered corners and shapes with rounded corners.

The vibrating portion 5 has one surface 5a and the other surface 5b opposite to the one surface 5a. A fixing region for the above-described piezoelectric element 4 is provided in a central portion C of one surface 5 a of the vibrating portion 5 . An adhesive, for example, is used to fix the piezoelectric element 4 to the one surface 5 a of the vibrating portion 5 . In the example of FIGS. 1 and 2, the long sides and short sides of the piezoelectric element 4 in plan view are smaller than the long sides and short sides of the vibrating portion 5 in plan view. In a plan view of the vibrating portion 5 , the long sides of the piezoelectric element 4 are along the long sides of the vibrating portion 5 , and the short sides of the piezoelectric element 4 are along the short sides of the vibrating portion 5 . In addition, the center position of the piezoelectric element 4 coincides with the center position of the vibrating portion 5 in plan view of the vibrating portion 5 . As a result, in a plan view of the vibrating portion 5, the entire piezoelectric element 4 overlaps the vibrating portion 5, and the piezoelectric element 4 does not protrude from the edge of the vibrating portion 5 (see FIG. 1).

The base portion 11 is a portion that serves as a support matrix for the piezoelectric vibrator 2 . The base portion 11 is formed in a thin plate shape by using a metal material, for example, and extends in the extension direction D. As shown in FIG. Examples of metal materials include Ni—Fe alloys, Ni, brass, and stainless steel. The base portion 11 may be made of a resin material. Examples of resin materials include polycarbonate (PC) and polyphenylene sulfide (PPS). Here, the base portion 11 has a rectangular shape that is one size larger than the vibrating portion 5 in plan view, and has a long side along the extending direction D and a short side perpendicular to the extending direction D. there is Rectangular shapes may also include, for example, shapes with chamfered corners and shapes with rounded corners.

The base portion 11 has one surface 11a and the other surface 11b opposite to the one surface 11a. The base portion 11 is arranged with a certain distance from the vibrating portion 5 with one surface 11 a facing the other surface 5 b of the vibrating portion 5 . Hereinafter, the direction in which the vibrating portion 5 and the base portion 11 face each other will be referred to as a facing direction E. As shown in FIG. The base portion 11 and the vibrating portion 5 are substantially parallel to each other when the vibrating portion 5 is not subjected to bending vibration. The distance between the base portion 11 and the vibrating portion 5 in the opposing direction E is set so that at least the base portion 11 and the vibrating portion 5 do not come into contact with each other when the vibrating portion 5 undergoes bending vibration.

The bending rigidity of the base portion 11 is equal to or higher than that of the vibrating portion 5 . For example, when the bending rigidity of the vibrating portion 5 is 7.7×10 ⁻³ Pa·m ⁴ , the bending rigidity of the base portion 11 is 7.7×10 ⁻³ Pa·m ⁴ to 9.7×10 ⁻¹ Pa·m ⁴ is preferred. Alternatively, the bending rigidity of the base portion 11 is preferably 1 to 130 times the bending rigidity of the vibrating portion 5 . The bending stiffness of the vibrating portion 5 and the base portion 11 can be measured by, for example, a tensile test or a resonance method. In setting the flexural rigidity of the base portion 11, for example, the base portion 11 may be made of a material having a hardness equal to or higher than that of the vibrating portion 5, or a material having a Young's modulus equal to or higher than that of the vibrating portion 5. 11 may be configured. Alternatively, the base portion 11 may be made of a material having a second elastic moment equal to or greater than that of the vibrating portion 5, for example. The thickness of the base portion 11 may be greater than or equal to the thickness of the vibrating portion 5 .

The support portion 12 is a portion that supports the vibrating portion 5 with a constant distance from the base portion 11 . The support portion 12 is formed in a thin plate shape from a metal material, for example, and extends in the width direction W. As shown in FIG. Examples of metal materials include Ni—Fe alloys, Ni, brass, and stainless steel. The base portion 11 may be made of a resin material. Examples of resin materials include polycarbonate (PC) and polyphenylene sulfide (PPS). Here, the support portion 12 has a rectangular shape when viewed from the extension direction D, and has long sides along the width direction W and short sides along the direction in which the base portion 11 and the vibrating portion 5 face each other. ing. The long side of the support portion 12 substantially matches the length of the short side of the vibrating portion 5 (the end portion 5c in the extending direction D), and the short side of the support portion 12 is the distance between the base portion 11 and the vibrating portion 5. approximately match the interval.

The support portion 12 is fixed to at least one end portion 5 c of the vibrating portion 5 in the extending direction D and the base portion 11 . In this embodiment, the support portions 12 are arranged in a pair corresponding to both end portions 5c, 5c of the vibrating portion 5 in the extending direction D. As shown in FIG. The pair of support portions 12, 12 are arranged in a direction orthogonal to the base portion 11 and the vibrating portion 5, and are fixed to both end portions 5c, 5c of the vibrating portion 5 in the extending direction D and the base portion 11, respectively. there is As a result, both ends 5c, 5c of the vibrating portion 5 in the extending direction D serve as fixed ends for bending vibration generated in the vibrating portion 5 by the piezoelectric element 4. As shown in FIG. Both ends 5c, 5c do not necessarily include the edge in the extending direction D of the vibrating portion 5. may also be positioned slightly closer to the center in the extending direction D.

Each of the pair of support portions 12 has one surface 12a and the other surface 12b opposite to the one surface 12a. One surface 12a faces the center side in the extending direction D (piezoelectric element 4 side), and the other surface 12b faces the outside in the extending direction D (opposite side of the piezoelectric element 4). The pair of support portions 12, 12 are arranged substantially parallel to each other with an interval corresponding to the length of the long side of the vibrating portion 5 in the extension direction D, with the one surfaces 12a, 12a facing each other. The vibrating portion 5, the base portion 11, and the pair of support portions 12, 12 have a rectangular shape when viewed in the width direction W (see FIG. 2).

For fixing the supporting portion 12 and the vibrating portion 5, for example, as shown in FIG. 3, a double-sided tape 15 can be used. In the example of FIG. 3, a protruding piece 16 protruding substantially perpendicularly from one surface 12a is provided at the end portion 12c of the supporting portion 12 on the vibrating portion 5 side. The protruding piece 16 is a portion for arranging the double-sided tape 15, and is provided, for example, over the entire long side of the supporting portion 12 on the vibrating portion 5 side. By interposing the double-sided tape 15 between the projecting piece 16 and the end portion 5c of the vibrating portion 5, the supporting portion 12 and the vibrating portion 5 are firmly fixed. It should be noted that the same technique as described above may be adopted for fixing the support portion 12 and the base portion 11 as well.

The support portion 12 is configured to be deformable toward the central portion C (see FIG. 2) in the extension direction D by following the bending vibration. In this embodiment, the bending rigidity of the support portion 12 is equal to or less than that of the vibrating portion 5 . For example, when the bending rigidity of the vibrating portion 5 is 7.7×10 ⁻³ Pa·m ⁴ , the bending rigidity of the support portion 12 is 5.9×10 ⁻⁵ Pa·m ⁴ to 7.7×10 ⁻³ Pa·m ⁴ is preferred. As a method for measuring the bending rigidity of the support portion 12, the method for measuring the bending rigidity of the vibrating portion 5 and the base portion 11 described above can be applied mutatis mutandis.

In the vibrating device 1 having such a configuration, when bending vibration is generated in the vibrating portion 5 by the piezoelectric element 4, as shown in FIG. It transforms to the part C side. For example, in FIG. 4, the vibrating portion 5 is curved according to the primary vibration mode of the bending vibration, and the antinode of the vibration waveform is positioned at the center of the extending direction D of the vibrating portion 5 . At this time, both end portions 5c of the vibrating portion 5, which are fixed ends of the bending vibration, tend to be displaced toward the central portion C side in the extending direction D as the vibrating portion 5 bends.

If the bending rigidity of the support portion 12 is high and the support portion 12 is not deformed in the extension direction D, the reaction force from the support portion 12 along with the bending of the vibrating portion 5 will move the vibrating portion outward in the extension direction D. 5. When such a reaction force acts on the vibrating portion 5, output distortion with respect to frequency is likely to occur, and it is conceivable that the sound pressure may decrease due to the output distortion. On the other hand, in the present embodiment, as shown in FIG. 4, the support portion 12 deforms toward the central portion C in the extending direction D following the bending vibration. Therefore, both end portions 5c, 5c of the vibrating portion 5 are easily displaced toward the central portion C side in the extending direction D during bending vibration, and the application of reaction force from the support portion 12 to the vibrating portion 5 is suppressed. be. As a result, the output distortion with respect to frequency can be improved, and the sound pressure can be improved.

In the present embodiment, the supporting portion 12 has a plate shape and is fixed to the entire end portion 5c of the vibrating portion 5 in the extending direction D. As shown in FIG. Further, the supporting portion 12 is fixed to both end portions 5c, 5c of the vibrating portion 5 in the extending direction D and to the base portion 11, respectively. Therefore, both ends 5c, 5c of the vibrating portion 5 in the extending direction D are entirely supported by the supporting portion 12, and bending vibration in the width direction W is suppressed. Therefore, in the bending vibration in the extension direction D, only the necessary vibration mode can be easily extracted, and the output distortion with respect to frequency can be further improved.

In this embodiment, the bending rigidity of the support portion 12 is equal to or less than that of the vibrating portion 5 . Thereby, followability of the support portion 12 to the central portion C side in the extending direction D can be further enhanced. Further, in this embodiment, the bending rigidity of the base portion 11 is equal to or greater than that of the vibrating portion 5 . Thereby, the stability of the base portion 11 can be secured.
[Second embodiment]

FIG. 5 is a schematic cross-sectional view showing the configuration of the vibration device according to the second embodiment. As shown in the figure, the vibrating device 21 according to the second embodiment differs from that of the above-described first embodiment in the configuration of the supporting portion 12 .

Specifically, the support portion 12 of the vibrating device 21 has an inclined portion 22 that inclines toward the central portion C side in the extending direction D from the base portion 11 side toward the vibrating portion 5 side. In the example of FIG. 5, the support portion 12 has a plate-like shape as in the first embodiment, and the entire support portion 12 is an inclined portion 22 inclined toward the central portion C side in the extending direction D. As shown in FIG. The vibrating portion 5, the base portion 11, and the pair of support portions 12, 12 form an isosceles trapezoidal shape when viewed in the width direction W. As shown in FIG. The inclination θ of the support portion 12 with respect to the base portion 11 can be set within a range of greater than 0° and less than 90° depending on the length of the vibrating portion 5 in the extending direction D, for example. In the vibrating device 21, the protruding piece 16 (see FIG. 3) used for fixing the supporting portion 12 and the vibrating portion 5 is arranged with respect to the one surface 12a of the supporting portion 12 according to the inclination θ of the supporting portion 12 with respect to the base portion 11. It is preferable to project at an obtuse angle.

In such a vibrating device 21 as well, the supporting portion 12 deforms toward the central portion C in the extending direction D following the bending vibration. Therefore, both end portions 5c, 5c of the vibrating portion 5 are easily displaced toward the central portion C side in the extending direction D during bending vibration, and the application of reaction force from the support portion 12 to the vibrating portion 5 is suppressed. be. As a result, the output distortion with respect to frequency can be improved, and the sound pressure can be improved. Further, in this embodiment, the support portion 12 has an inclined portion 22 that inclines toward the central portion C side in the extending direction D as it goes from the base portion 11 side toward the vibrating portion 5 side. By providing such an inclined portion 22 in the support portion 12, the followability of the support portion 12 to the central portion C side in the extending direction D can be further enhanced.

In the example of FIG. 5, the entire support portion 12 is the inclined portion 22 inclined toward the central portion C side in the extending direction D, but the base end side (base portion 11 side) of the support portion 12 is the base portion. 11, and only the distal end side (vibrating portion 5 side) of the support portion 12 may be an inclined portion 22 that is inclined toward the central portion C side in the extending direction D. As shown in FIG. Further, the form of inclination is not necessarily limited to a form of linear inclination, and may be a form of curved inclination or a form of stepped inclination. The thickness of the support portion 12 may be gradually reduced from the base portion 11 side toward the vibrating portion 5 side.
[Modification]

The present disclosure is not limited to the above embodiments. For example, in the above-described embodiment, the double-sided tape 15 is used to fix the support section 12 and the vibrating section 5 (see FIG. 3). can. For example, as shown in FIG. 6A, a bolt 31 and a nut 32 may be used to fix the protruding piece 16 of the support portion 12 and the end portion 5c of the vibrating portion 5, and FIG. , a fitting groove 33 is provided on the other surface 5b side of the end portion 5c of the vibrating portion 5, and the end portion 12c of the supporting portion 12 on the vibrating portion 5 side is fitted into the fitting groove 33. good. As shown in FIG. 6(c), the supporting portion 12 and the vibrating portion 5 may be integrally formed. 6(b) and 6(c), the protruding piece 16 of the support portion 12 is not required.

2 and 5 illustrate the plate-like support portion 12 having a uniform thickness, the support portion 12 may be provided with a constricted portion 34 or a slit 35 . In this case, for example, as shown in FIG. 7(a), one surface 12a and the other surface 12b of the support portion 12 may be curved to form a narrowed portion 34, as shown in FIG. 7(b). Thus, the narrowed portion 34 may be provided by partially cutting out the supporting portion 12 to have a predetermined shape (here, a triangular cross-sectional shape). These narrowed portions 34 may be provided on only one of the one surface 12 a and the other surface 12 b of the support portion 12 .

Further, as shown in FIG. 7C, the support portion 12 may be provided with a plurality of linear slits 35 . In the example of FIG. 7C, the slits 35 extend along the long side direction (width direction W) of the support portion 12 and are provided in multiple rows at predetermined intervals along the short side direction (facing direction E). ing. The slit 35 may be provided in a direction orthogonal to FIG. 7(c). That is, the slits 35 may extend along the short side direction (opposing direction E) of the support portion 12 and may be provided in multiple rows at predetermined intervals along the long side direction (width direction W). Thus, according to the configuration in which the narrowed portion 34 or the slit 35 is provided in the support portion 12, the bending rigidity of the support portion 12 can be easily reduced, and the support portion toward the central portion C side in the extending direction D 12 can be further enhanced.

DESCRIPTION OF SYMBOLS 1, 21... Vibration device 4... Piezoelectric element 5... Vibration part 5c... End part 11... Base part 12... Support part 22... Inclined part 34... Constriction part 35... Slit C... Central part , D... extending direction (one direction).

Claims (7)

a piezoelectric element;
a vibrating portion to which the piezoelectric element is fixed and which generates bending vibration by driving the piezoelectric element;
a base portion facing the vibrating portion;
a support portion fixed to at least one end of the vibrating portion and the base portion, and supporting the vibrating portion with a constant spacing from the base portion;
The vibration device, wherein the support portion is configured to be deformable following the bending vibration. 2. The vibrating device according to claim 1, wherein the supporting portion has a plate shape and is fixed to the entire end portion of the vibrating portion. The vibrating portion extends in one direction,
3. The vibrating device according to claim 1, wherein the supporting portion is fixed to both ends of the vibrating portion in the one direction and to the base portion, respectively. 4. The vibrating device according to claim 3, wherein the supporting portion has an inclined portion that inclines toward the center portion side in the one direction from the base portion side toward the vibrating portion side. The vibrating device according to any one of claims 1 to 4, wherein the supporting portion is provided with a narrowed portion or a slit. The vibrating device according to any one of claims 1 to 5, wherein the bending rigidity of the supporting portion is equal to or less than that of the vibrating portion. The vibrating device according to any one of claims 1 to 6, wherein the bending rigidity of the base portion is equal to or higher than that of the vibrating portion.

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