Vibration device

Abstract

To provide a vibration device having improved acoustic characteristics.SOLUTION: A vibration device 1 includes a piezoelectric part 2 including a piezoelectric element 5, a housing 3 that holds the piezoelectric part 2, a wiring member 4 that is electrically connected to the piezoelectric part 2, and a bonding member P that bonds the housing 3 to an external device. The housing 3 includes a bottom surface part 11 to which the piezoelectric part 2 is fixed and a side surface part 12 that stands on an edge part of the bottom surface part 11, and the side surface part 12 includes a first surface F1 formed on a top part 12a of the side surface part 12 and a second surface F2 that is one step lower than a first surface F1 by a notch part 33 formed on the top part 12a. The bonding member P extends along the first surface F1 so as to span a notch part 33, and the wiring member 4 is bonded to the bonding member P at a position of the first surface F1 and passes through the notch part 33 in a state of not being bonded to a second surface F2.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to vibration devices. [Background technology]

[0002] An example of a conventional vibration device is the acoustic generator described in Patent Document 1. This conventional acoustic generator includes a piezoelectric element having a surface electrode, a vibrating body to which the piezoelectric element is attached, a frame that supports the vibrating body, and a wiring member having one end connected to the surface electrode and the other end fixed to the frame. The width of the other end of the wiring member is wider than the width of the other parts. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-017426 Summary of the Invention [Problem to be solved by the invention]

[0004] The vibration device described above is characterized by obtaining desired acoustic characteristics through vibration of the housing. To obtain the desired acoustic characteristics, it is important to stabilize the air space characteristics within the housing when the vibration device is attached to an external device. Because wiring members electrically connected to the piezoelectric element are present within the housing, it is thought that it is necessary to devise a way to prevent the wiring members from affecting the air space design accuracy when the vibration device is attached to an external device.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a vibration device that has improved acoustic characteristics. [Means for solving the problem]

[0006] A vibration device according to one aspect of the present disclosure comprises a piezoelectric portion including a piezoelectric element, a housing that holds the piezoelectric portion, a wiring member electrically connected to the piezoelectric portion, and a joining member that joins the housing to an external device, wherein the housing has a bottom portion to which the piezoelectric portion is fixed and a side portion that stands on the edge of the bottom portion, the side portion having a first surface formed at the top of the side portion and a second surface that is one step lower from the first surface by a notch formed at the top, the joining member extends along the first surface so as to span the notch, and the wiring member is joined to the joining member at the position of the first surface and is passed through the notch in a state where it is not joined to the second surface.

[0007] In this resonator device, a bonding member that bonds the housing to an external device is disposed on the first surface at the top of the side portion. This allows for stable attachment of the resonator device to an external device. Furthermore, in this resonator device, the wiring member is passed through a notch provided on the top of the side portion and is bonded to a bonding member that spans the notch at the first surface, while remaining unbonded to a second surface that is one step lower than the first surface. Bonding the wiring member to the bonding member on the first surface prevents the wiring member from wobbling around the piezoelectric portion, thereby avoiding any impact on the cavity design accuracy. Furthermore, since the wiring member is not bonded to the second surface, the flatness of the bonding member on the first surface is maintained even if dimensional errors occur in the notch or other areas, maintaining the stability of the attachment of the resonator device. Therefore, in this resonator device, the cavity characteristics around the piezoelectric portion can be easily ensured, improving acoustic characteristics.

[0008] The bonding member may be bonded to at least a portion of the second surface. In this case, bonding the wiring member to both the first surface and the second surface more reliably prevents the wiring member from wobbling around the piezoelectric portion.

[0009] The bonding area between the wiring member and the bonding member may be larger than the bonding area between the second surface and the bonding member, which can prevent excessive bonding between the second surface and the bonding member and maintain the flatness of the bonding member on the first surface.

[0010] The wiring member may be tensioned in the direction of extension of the wiring member between the piezoelectric portion and the notch. This can prevent the wiring member from interfering with the housing and generating a collision noise even when vibration is applied to the housing. This can prevent the influence of vibration on the cavity characteristics.

[0011] The side surface may be smoothly connected to the bottom surface and inclined so as to open outward from the edge of the bottom surface. In this case, vibrations are efficiently transmitted from the bottom surface, where the piezoelectric element is located, to the side surface, and vibrations from the side surface as well as the bottom surface can be sufficiently extracted as output. This further improves the acoustic characteristics. [Effects of the Invention]

[0012] According to the present disclosure, acoustic characteristics are improved. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view illustrating an embodiment of a vibration device according to the present disclosure. [Figure 2] FIG. 2 is a plan view of the vibration device shown in FIG. [Figure 3] FIG. 2 is a front view of the vibration device shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 2 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 10 is a schematic cross-sectional view showing another example of the arrangement of the joining members. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, preferred embodiments of a vibration device according to one aspect of the present disclosure will be described in detail with reference to the drawings.

[0015] 1 is a perspective view showing one embodiment of a vibration device according to the present disclosure. The vibration device 1 is an acoustic device used as, for example, a speaker, a buzzer, etc. As shown in FIG. 1, the vibration device 1 is configured to include a piezoelectric portion 2, a housing 3, and a wiring member 4.

[0016] The piezoelectric unit 2 includes a piezoelectric element 5. The piezoelectric element 5 includes a piezoelectric body and a pair of external electrodes. The piezoelectric element 5 has a rectangular parallelepiped shape that is flat in the thickness direction. The rectangular parallelepiped shape may include a shape in which the corners and ridges are chamfered or a shape in which the corners and ridges are rounded. The piezoelectric body is formed by a laminate of multiple piezoelectric layers. Each piezoelectric layer is formed of a piezoelectric material such as a piezoelectric ceramic. Examples of piezoelectric ceramic materials include PZT [Pb(Zr,Ti)O3], PT(PbTiO3), PLZT [(Pb,La)(Zr,Ti)O3], and barium titanate (BaTiO3).

[0017] Each piezoelectric layer is made of, for example, a sintered ceramic green sheet containing the above-mentioned piezoelectric ceramic. In an actual piezoelectric element, the piezoelectric layers are integrated to the extent that the boundaries between the layers are indistinguishable. A plurality of internal electrodes (not shown) are disposed within the piezoelectric element. Each internal electrode is made of a conductive material. Examples of conductive materials include Ag, Pd, and Ag-Pd alloys.

[0018] The piezoelectric part 2 may be a combination of a piezoelectric element 5 and a diaphragm. The diaphragm is a plate-shaped member made of, for example, a metal material. Examples of metal materials that can be used to make the diaphragm include Ni-Fe alloy, Ni, brass, and stainless steel. The diaphragm has, for example, a rectangular shape. The diaphragm is placed on the bottom surface (the surface facing the housing 3) of the piezoelectric element 5, and can be fixed to the piezoelectric element 5 and the housing 3 using, for example, an adhesive, double-sided tape, or the like.

[0019] The housing 3 is a member that holds the piezoelectric portion 2. The housing 3 is formed, for example, by pressing a metal. Examples of metal materials that form the housing 3 include stainless steel, aluminum, and 42Ni alloy. The housing 3 has a bottom surface portion 11 and a plurality of side surfaces 12. The bottom surface portion 11 is a portion to which the above-mentioned piezoelectric portion 2 is fixed. Here, the side surfaces 12 are erected at the edge of the bottom surface portion 11 so as to surround the piezoelectric portion 2.

[0020] An outward flange 13 is provided on the top 12a of the side surface 12. The flange 13 protrudes from the top 12a of the side surface 12 by a predetermined width parallel to the bottom surface 11. The flange 13 functions as an attachment portion for attaching the vibration device 1 to an external device. A double-sided tape 41, which will be described later, is attached to one surface of the flange 13 (the surface opposite the bottom surface 11).

[0021] The wiring member 4 is a member that electrically connects the piezoelectric portion 2 and an external device. The wiring member 4 is, for example, a flexible printed circuit (FPC). One end of the wiring member 4 is electrically connected to each of a pair of external electrodes of the piezoelectric element 5 on the side of one surface 2a of the piezoelectric portion 2. For example, an anisotropic conductive adhesive can be used to connect one end of the wiring member 4 to the external electrodes of the piezoelectric element 5. The other end (not shown) of the wiring member 4 is electrically connected to an external device.

[0022] Next, the configuration of the housing 3 and the positional relationship between the piezoelectric section 2 and the housing 3 will be described with reference to FIGS.

[0023] FIG. 2 is a plan view of the vibration device shown in FIG. 1, and FIG. 3 is a front view thereof. For ease of explanation, the wiring member 4 and the double-sided tape 41 described below are omitted from FIGS. 2 and 3. The piezoelectric portion 2 is also omitted from FIG. 3. As shown in FIGS. 2 and 3, in this embodiment, the piezoelectric portion 2 has a rectangular shape in a plan view. The planar shape of the piezoelectric portion 2 is the planar shape of the piezoelectric element 5 when the piezoelectric portion 2 is composed only of the piezoelectric element 5, and is the planar shape of the vibration plate when the piezoelectric portion is composed of the piezoelectric element 5 and a vibration plate.

[0024] The bottom surface portion 11 of the housing 3 is trapezoidal in plan view. That is, the bottom surface portion 11 has an upper base 21, a lower base 22, and a pair of oblique sides 23, 23. Here, as shown in FIG. 2, the planar shape of the bottom surface portion 11 is an isosceles trapezoid. The lower base 22 of the bottom surface portion 11 is larger than the upper base 21. That is, the bottom surface portion 11 widens from the upper base 21 to the lower base 22. The piezoelectric portion 2 is located approximately in the center of the bottom surface portion 11. The bottom surface portion 11 is the main vibrating portion of the housing 3, and vibrations from the piezoelectric portion 2 are directly transmitted to the bottom surface portion 11.

[0025] The upper base 21 and the lower base 22 of the bottom surface portion 11 extend along the long sides 24 of the piezoelectric portion 2 in a plan view. The upper base 21 of the bottom surface portion 11 is shorter than the long sides 24 of the piezoelectric portion 2, and the lower base 22 of the bottom surface portion 11 is longer than the long sides 24 of the piezoelectric portion 2. A certain distance is provided between the lower base 22 of the bottom surface portion 11 and the long sides 24 of the piezoelectric portion 2. This distance is shorter than the short sides 25 of the piezoelectric portion 2, for example.

[0026] The side surface portions 12 are provided to correspond to the upper base 21 and the pair of oblique sides 23, 23 of the bottom surface portion 11. The height of the side surface portions 12 is greater than the thickness of the piezoelectric portion 2. As a result, the piezoelectric portion 2 arranged on the bottom surface portion 11 is surrounded by the side surface portions 12 from three directions except for the lower base 22 side. The side surface portions 12 are smoothly continuous with the bottom surface portion 11 and are inclined relative to the bottom surface portion 11 so as to open outward from the edges. The side surface portions 12 are secondary vibrating portions of the housing 3, and vibrations caused by the piezoelectric portion 2 are transmitted via the bottom surface portion 11.

[0027] A first opening 31 is formed on the lower base 22 side of the bottom surface portion 11 due to the absence of the side surface portion 12. As shown in Fig. 3, the first opening 31 is defined by the bottom surface portion 11, the side surface portions 12, 12 corresponding to the oblique sides 23, 23 of the bottom surface portion 11, and an imaginary line connecting one surface (the surface for mounting to an external device) of the flange portions 13, 13 on the side surface portions 12, 12. The first opening 31 functions as an outlet for extracting vibrations generated by the piezoelectric portion 2 to the outside when the vibration device 1 is mounted to an external device.

[0028] A second opening 32 is formed on the upper bottom 21 side of the bottom surface 11 by cutting out a portion of the apex 12a of the side surface 12. As shown in FIG. 3 , the second opening 32 is defined by a notch 33 formed in the side surface 12 corresponding to the upper bottom 21 of the bottom surface 11 and an imaginary line connecting the apexes 12a, 12a of the side surface 12 that sandwich the notch 33. The width of the notch 33 is slightly larger than the width of the wiring member 4. The depth of the notch 33 from the apex 12a of the side surface 12 is the same as or slightly larger than the thickness of the wiring member 4. The second opening 32 functions as an outlet for the wiring member 4 electrically connected to the piezoelectric portion 2 when the resonation device 1 is attached to an external device.

[0029] Next, the holding structure of the above-mentioned wiring member 4 will be described with reference to FIGS.

[0030] Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 1, and Fig. 5 is a cross-sectional view taken along line VV in Fig. 1. As shown in Fig. 4 and Fig. 5, in order to hold the wiring member 4, the side surface portion 12 has a first surface F1 formed on the top portion 12a of the side surface portion 12, and a second surface F2 that is one step lower than the first surface F1 by the above-mentioned notch portion 33 formed on the top portion 12a.

[0031] In this embodiment, as shown in FIG. 1 , the first surface F1 is defined by the tops 12a of the three side surfaces 12 corresponding to the upper base 21 and the pair of oblique sides 23, 23 of the bottom surface 11, and the three flanges 13 connected to these tops 12a. In a plan view of the housing 3, the first surface F1 is defined so as to surround the periphery of the piezoelectric portion 2 in three directions, excluding the position where the notch 33 is formed. The second surface F2 is defined by the bottom surfaces 33a of the notch 33. The second surface F2 is located closer to the bottom surface 11 than the first surface F1, at a distance equal to or slightly greater than the thickness of the wiring member 4. The height of the second surface F2 from the bottom surface 11 is greater than the height of one surface 2a of the piezoelectric portion 2 from the bottom surface 11.

[0032] A joining member P that joins the housing 3 to an external device is disposed on the first surface F1. Here, the joining member P is made of double-sided tape 41. The double-sided tape 41 is disposed over substantially the entire surface of the first surface F1. As shown in FIG. 4, the double-sided tape 41 is disposed so as to span the notch 33 at the position of the notch 33. Therefore, the double-sided tape 41 is spaced apart from the second surface F2 by a distance approximately equal to the depth of the notch 33. The joining member P may be made of an epoxy adhesive, a urethane adhesive, silicone, or the like.

[0033] 4, the wiring member 4 is passed through the notch 33 between the first surface F1 and the second surface F2. The wiring member 4 is bonded to the double-sided tape 41 at the position of the first surface F1. On the other hand, the wiring member 4 is not bonded to the second surface F2. The wiring member 4 may be in contact with the second surface F2 or may be spaced apart from the second surface F2.

[0034] The wiring member 4 is connected to one surface 2a of the piezoelectric portion 2 using an anisotropic conductive adhesive or the like. The wiring member 4 is also passed through the notch 33 and bonded to double-sided tape 41 at the position of the first surface F1. Between the piezoelectric portion 2 and the notch 33, the wiring member 4 is arranged at an inclination that gradually increases in height toward the notch 33. As shown in FIG. 5, the wiring member 4 is linearly inclined at a certain angle from the edge of the piezoelectric portion 2 on the notch 33 side to the edge of the notch 33 on the piezoelectric portion 2 side. In this state, tension (arrow A in FIG. 5) is applied to the wiring member 4 in the extending direction of the wiring member 4 between the piezoelectric portion 2 and the notch 33.

[0035] As described above, in the vibration device 1, the double-sided tape 41 that joins the housing 3 to an external device is disposed on the first surface F1 of the top 12a of the side surface portion 12. In this embodiment, the side surface portion 12 is disposed so as to surround the piezoelectric portion 2 from three directions, and the first surface F1 is formed by the top 12a of the side surface portion 12 and the flange portion 13 provided on the top 12a. This makes it possible to adhere the housing 3 to the external device via the double-sided tape 41, thereby stably attaching the vibration device 1 to the external device.

[0036] Furthermore, in the vibration device 1, the wiring member 4 is passed through a notch 33 provided in the top 12a of the side surface 12 and is bonded to double-sided tape 41 that is hung over the notch 33 at the position of the first surface F1, while being unbonded to a second surface F2 that is one step below the first surface F1. Bonding the wiring member 4 to the double-sided tape 41 on the first surface F1 prevents the wiring member 4 from wobbling around the piezoelectric portion 2, thereby avoiding any impact on the cavity design accuracy. Since the wiring member 4 is not bonded to the second surface F2, the flatness of the bonding member P on the first surface F1 is maintained even if dimensional errors occur in the notch or the like, and the mounting state of the vibration device 1 is maintained in a stable manner. Therefore, in the vibration device 1, the cavity characteristics around the piezoelectric portion 2 can be easily ensured, improving acoustic characteristics.

[0037] In this embodiment, tension is applied to the wiring member 4 between the piezoelectric portion 2 and the notch 33 in the extending direction of the wiring member 4. This makes it possible to suppress the generation of collision noise caused by the wiring member 4 interfering with the housing 3 even when vibration is applied to the housing 3. Therefore, it is possible to avoid the influence of vibration on the room characteristics.

[0038] In this embodiment, the side surface portion 12 is smoothly continuous with the bottom surface portion 11 and is inclined so as to open outward from the edge of the bottom surface portion 11. This allows vibration to be efficiently transmitted from the bottom surface portion 11, where the piezoelectric portion 2 is arranged, to the side surface portion 12, and the vibration of the side surface portion 12 as well as the vibration of the bottom surface portion 11 can be sufficiently extracted as output. This further improves the acoustic characteristics.

[0039] The present disclosure is not limited to the above-described embodiment. For example, in the above-described embodiment, the planar shape of the bottom surface 11 of the housing 3 is trapezoidal, but the planar shape of the bottom surface 11 is not limited to this and may be other shapes such as rectangular, square, circular, or elliptical.

[0040] Furthermore, in the above embodiment, the double-sided tape 41 is spaced apart from the second surface F2 by a distance approximately equal to the depth of the cutout 33, but as shown in Fig. 6, the double-sided tape 41 may be bonded to at least a portion of the second surface F2. In the example of Fig. 6, the double-sided tape 41 bends toward the cutout 33 on both sides of the wiring member 4 and is bonded to the second surface F2 near the apex of the bent portion. With this configuration, the wiring member 4 is bonded to both the first surface F1 and the second surface F2, which more reliably prevents the wiring member 4 from wobbling around the piezoelectric portion 2.

[0041] When the double-sided tape 41 is bonded to at least a portion of the second surface F2, it is preferable that the bonding area S1 between the wiring member 4 and the double-sided tape 41 is larger than the bonding area S2 between the second surface F2 and the double-sided tape 41. In this case, excessive bonding between the second surface F2 and the double-sided tape 41 can be avoided, and the flatness of the double-sided tape 41 on the first surface F1 can be maintained. [Explanation of symbols]

[0042] 1...vibration device, 2...piezoelectric part, 3...casing, 4...wiring member, 5...piezoelectric element, 11...bottom part, 12...side part, 33...notch part, 41...double-sided tape, F1...first surface, F2...second surface, P...joint member.

Claims

1. a piezoelectric portion including a piezoelectric element; a housing that holds the piezoelectric portion; a wiring member electrically connected to the piezoelectric portion; a joining member that joins the housing to an external device, the housing has a bottom surface portion to which the piezoelectric portion is fixed and a side surface portion provided upright on an edge portion of the bottom surface portion, the side surface portion has a first surface formed at a top of the side surface portion and a second surface that is one step lower than the first surface by a notch portion formed at the top of the side surface portion, the joining member extends along the first surface so as to span the notch portion, A vibration device in which the wiring member is joined to the joining member at the first surface and passed through the notch in a state where it is not joined to the second surface.

2. The vibration device according to claim 1 , wherein the joining member is joined to at least a portion of the second surface.

3. The resonation device according to claim 2 , wherein a bonding area between the wiring member and the bonding member is larger than a bonding area between the second surface and the bonding member.

4. 4. The vibration device according to claim 1, wherein tension is applied to the wiring member between the piezoelectric portion and the notch in the direction in which the wiring member extends.

5. The vibration device according to any one of claims 1 to 4, wherein the side surface portion is smoothly continuous with the bottom surface portion and is inclined relative to the bottom surface portion so as to open outward from the edge portion.

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