Vibration device

Abstract

To provide a vibration device that obtains desired acoustic characteristics in the vibration of a housing by studying the structure of the housing and improving the acoustic characteristics.SOLUTION: A vibration device 1 includes a piezoelectric portion 2 including a piezoelectric element 5, and a metal housing 3 that holds the piezoelectric portion 2. The housing 3 includes a bottom surface portion 11 to which the piezoelectric portion 2 is fixed, and a side surface portion 12 erected so as to surround the piezoelectric portion 2 at the edge of the bottom surface portion 11. The side surface portion 12 is continuous with the bottom surface portion 11 and is slanted with respect to the bottom surface portion 11 so as to open to the outside of the edge portion.SELECTED DRAWING: Figure 1

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 film, a frame member provided on the outer periphery of the film, a piezoelectric element provided on the film, and a resin layer filled within the frame member so as to cover the piezoelectric element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-133750 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 the vibration of the housing. Therefore, the technical challenge is to consider the configuration of the housing and improve the acoustic characteristics.

[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 and a metal housing that holds the piezoelectric portion, the housing having a bottom surface to which the piezoelectric portion is fixed and a side surface that is erected at the edge of the bottom surface to surround the piezoelectric portion, the side surface being continuous with the bottom surface and inclined relative to the bottom surface so as to open outward from the edge.

[0007] In this vibration device, the housing that holds the piezoelectric unit is made of metal. The side surfaces surrounding the piezoelectric unit are continuous with the bottom surface and are inclined outward relative to the bottom surface. This configuration allows vibrations to be efficiently transmitted from the bottom surface where the piezoelectric unit is located to the side surfaces, allowing sufficient vibrations from the side surfaces to be extracted as output along with the vibrations from the bottom surface. This improves acoustic characteristics.

[0008] Both the inner and outer surfaces of the side portion may be inclined relative to the bottom portion. In this case, the overall thickness of the side portion is reduced, and the efficiency of vibration transmission from the bottom portion to the side portion can be increased, thereby further improving the acoustic characteristics.

[0009] The ridge portion of the piezoelectric element and the connection portion between the bottom surface and the side surface may both be curved, and the radius of curvature of the connection portion may be larger than the radius of curvature of the ridge portion of the piezoelectric element. This increases the efficiency of vibration transmission from the bottom surface to the side surface. Furthermore, the height of the side surface relative to the bottom surface can be reduced while ensuring the area of ​​the side surface necessary for vibration. This contributes to a low profile of the vibration device.

[0010] The piezoelectric portion has a rectangular shape in plan view, and the bottom portion has a trapezoidal shape with its upper and lower bases corresponding to the long sides of the piezoelectric portion in plan view, and the upper base of the bottom portion may be shorter than the long sides of the piezoelectric portion, and the lower base of the bottom portion may be longer than the long sides of the piezoelectric portion. This configuration improves acoustic characteristics, particularly in the high frequency range.

[0011] The distance between the lower base of the bottom portion and the long side of the piezoelectric portion along the lower base may be shorter than the short side of the piezoelectric portion, thereby improving acoustic characteristics particularly in the high frequency range.

[0012] A first opening may be formed on the lower bottom side of the bottom surface portion by not providing the side surface portion, in which case vibrations can be efficiently extracted from the first opening.

[0013] A second opening may be formed on the upper side of the bottom surface by cutting out a part of the top of the side surface, in which case the second opening can be used as an outlet for the wiring member.

[0014] The opening area of ​​the first opening may be larger than the opening area of ​​the second opening. In this case, vibrations can be extracted preferentially from the first opening over the second opening. This allows for both improved acoustic characteristics and simplified layout of wiring members, etc.

[0015] The side surface may have an outward flange at its top, which can facilitate attachment of the resonation device to an external device.

[0016] The radius of curvature of the connection between the side portion and the flange portion may be smaller than the radius of curvature of the connection between the bottom portion and the side portion. This can suppress the transmission of vibration from the side portion to the flange portion. Therefore, it is possible to prevent the vibration of the side portion from being weakened by the flange portion. Furthermore, it is possible to suppress a decrease in the attachment strength of the vibration device to an external device due to vibration of the flange portion. [Effects of the Invention]

[0017] According to the present disclosure, acoustic characteristics are improved. [Brief explanation of the drawings]

[0018] [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. DETAILED DESCRIPTION OF THE INVENTION

[0019] 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.

[0020] 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.

[0021] 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).

[0022] 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.

[0023] 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.

[0024] 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 piezoelectric portion 2 described above is fixed. The side surfaces 12 are erected at the edges of the bottom surface portion 11 so as to surround the piezoelectric portion 2.

[0025] 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. One surface of the flange 13 (the surface opposite the bottom surface 11) serves as an attachment surface on which an attachment member such as double-sided tape is provided. As the attachment member, an adhesive can also be used in addition to double-sided tape.

[0026] The wiring member 4 is a member that electrically connects the piezoelectric portion 2 to 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. 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.

[0027] Next, the configuration of the housing 3 and the positional relationship between the piezoelectric section 2 and the housing 3 will be described in more detail.

[0028] 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 is not shown in FIGS. 2 and 3. The piezoelectric portion 2 is also not shown in 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.

[0029] 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.

[0030] The upper base 21 and the lower base 22 of the bottom portion 11 extend along the long sides 24 of the piezoelectric portion 2 in a plan view. The upper base 21 of the bottom portion 11 is shorter than the long sides 24 of the piezoelectric portion 2, and the lower base 22 of the bottom portion 11 is longer than the long sides 24 of the piezoelectric portion 2. A constant distance D1 is provided between the lower base 22 of the bottom portion 11 and the long sides 24 of the piezoelectric portion 2. The distance D1 is shorter than the short sides 25 of the piezoelectric portion 2. Similarly, a constant distance D2 is provided between the upper base 21 of the bottom portion 11 and the long sides 24 of the piezoelectric portion 2. The distance D2 is shorter than the short sides 25 of the piezoelectric portion 2. In this embodiment, the distance D1 is equal to or greater than the distance D2. The distance D1 may be shorter than the distance D2.

[0031] 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.

[0032] The side surface portion 12 has a connection portion 12A with the bottom surface portion 11, a connection portion 12B with the flange portion 13, and an intermediate portion 12C located between the connection portions 12A and 12B. In this embodiment, as shown in FIG. 3 , the connection portion 12A and the intermediate portion 12C form an integral arc-shaped cross section that bulges outward from the housing 3. In this embodiment, the thickness of the connection portion 12A and the intermediate portion 12C is constant and the same as the thickness of the bottom surface portion 11. Therefore, both the inner surface 12b and the outer surface 12c of the side surface portion 12 are gently curved and inclined relative to the bottom surface portion 11.

[0033] If the radius of curvature of the ridgeline portion of the piezoelectric element 5 is R1 and the radius of curvature of the connection portion 12A is R2, the radius of curvature R2 of the connection portion 12A is larger than the radius of curvature R1 of the ridgeline portion of the piezoelectric element 5. The ratio of the radii of curvature R1 to the radii of curvature R2 is, for example, 1:2 or more. By making the radius of curvature R2 larger than the radius of curvature R1, the ability of the bottom surface portion 11 to follow the vibration of the piezoelectric element 5 is improved, and sufficient displacement of the bottom surface portion 11 is ensured. As a result, the sound pressure of the vibration device 1 is improved.

[0034] On the other hand, the connecting portion 12B has an arc-shaped cross section facing away from the connecting portion 12A and the intermediate portion 12C. In this embodiment, the thickness of the connecting portion 12B is constant and the same as the thickness of the bottom surface portion 11, the connecting portion 12A, and the intermediate portion 12C. If the radius of curvature of the connecting portion 12B is R3, the radius of curvature R3 of the connecting portion 12B is smaller than the radius of curvature R2 of the connecting portion 12A. There are no particular restrictions on the relationship between the radius of curvature R3 of the connecting portion 12B and the radius of curvature R1 of the ridge portion of the piezoelectric element 5. The radius of curvature R3 of the connecting portion 12B may be equal to or greater than the radius of curvature R1 of the ridge portion of the piezoelectric element 5, or may be smaller than the radius of curvature R1 of the ridge portion of the piezoelectric element 5.

[0035] 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.

[0036] 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.

[0037] The height of the bottom surface 33a of the cutout 33 relative to the bottom surface 11 is higher than the height of the piezoelectric portion 2 (height of the top surface of the piezoelectric element 5) relative to the bottom surface 11. The wiring member 4 is disposed between the piezoelectric portion 2 and the cutout 33 at an incline so that the height gradually increases toward the cutout 33, and a certain tension is applied to the wiring member 4.

[0038] In this embodiment, the opening area S1 of the first opening 31 is larger than the opening area S2 of the second opening 32. This allows the vibration of the piezoelectric portion 2 to be preferentially extracted from the first opening 31. The frequency characteristics of the vibration device 1 are determined by the combination of the opening area S1 and the opening area S2. The resonance of the first opening 31 and the resonance of the second opening 32 are utilized to adjust the overall frequency characteristics of the vibration device 1. The corners and edges of the cutout 33 may be chamfered or rounded. The inner surface of the cutout 33 may be inclined or curved so that the width of the cutout 33 increases toward the top 12a of the side surface 12.

[0039] As described above, in the vibration device 1, the housing 3 that holds the piezoelectric portion 2 is made of metal. The side surface portions 12 that surround the piezoelectric portion 2 are continuous with the bottom surface portion 11 and are inclined so as to open outward relative to the bottom surface portion 11. With this configuration, vibrations are efficiently transmitted from the bottom surface portion 11 on which the piezoelectric portion 2 is disposed to the side surface portions 12, and the vibrations of the side surface portions 12 as well as the vibrations of the bottom surface portion 11 can be sufficiently extracted as output. This improves acoustic characteristics.

[0040] In the resonation device 1, both the inner surface 12b and the outer surface 12c of the side surface portion 12 are inclined with respect to the bottom surface portion 11. This reduces the overall thickness of the side surface portion 12, and improves the efficiency of vibration transmission from the bottom surface portion 11 to the side surface portion 12. This further improves the acoustic characteristics.

[0041] In the vibration device 1, the ridge line portion of the piezoelectric portion 2 and the connection portion 12A between the bottom surface portion 11 and the side surface portion 12 are both curved, and the radius of curvature R2 of the connection portion 12A is larger than the radius of curvature R1 of the ridge line portion of the piezoelectric element 5. This increases the efficiency of vibration transmission from the bottom surface portion 11 to the side surface portion 12. Furthermore, the height of the side surface portion 12 relative to the bottom surface portion 11 can be reduced while ensuring the area of ​​the side surface portion 12 necessary for vibration. This contributes to a low profile of the vibration device 1.

[0042] In the vibration device 1, the piezoelectric portion 2 has a rectangular shape in a plan view. In addition, the bottom surface portion 11 has a trapezoidal shape with an upper base 21 and a lower base 22 that correspond to the long sides 24 of the piezoelectric portion 2 in a plan view. The upper base 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. In addition, in the vibration device 1, the distance D between the lower base 22 of the bottom surface portion 11 and the long sides 24 of the piezoelectric portion 2 that are along the lower base 22 is shorter than the short sides 25 of the piezoelectric portion 2. This configuration improves acoustic characteristics, particularly in the high frequency range.

[0043] In the resonation device 1, a first opening 31 is formed on the lower base 22 side of the bottom surface portion 11 by not providing the side surface portion 12. This allows vibrations to be efficiently extracted from the first opening 31. Also, in the resonation device 1, a second opening 32 is formed on the upper base 21 side of the bottom surface portion 11 by cutting out a part of the top 12a of the side surface portion 12. This allows the second opening 32 to be used as an outlet for the wiring member 4.

[0044] In the resonator device 1, the opening area S1 of the first opening 31 is larger than the opening area S2 of the second opening 32. This allows vibrations to be extracted preferentially from the first opening 31 over the second opening 32. This achieves both improved acoustic characteristics and simplified layout of the wiring member 4 and the like.

[0045] In the vibration device 1, an outward flange portion 13 is provided on the top portion 12a of the side surface portion 12. Such a flange portion 13 can improve ease of attachment when attaching the vibration device 1 to an external device.

[0046] In the vibration device 1, the radius of curvature R3 of the connection portion 12B between the side surface portion 12 and the flange portion 13 is smaller than the radius of curvature R2 of the connection portion 12A between the bottom surface portion 11 and the side surface portion 12. This makes it possible to suppress the transmission of vibration from the side surface portion 12 to the flange portion 13. Therefore, it is possible to prevent the vibration of the side surface portion 12 from being weakened by the flange portion 13. It is also possible to suppress a decrease in the attachment strength of the vibration device 1 to an external device due to vibration of the flange portion 13.

[0047] 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.

[0048] Furthermore, in the above embodiment, the connecting portion 12A and the intermediate portion 12C have an integral arc-shaped cross section, but only the connecting portion 12A may have an arc-shaped cross section, and the intermediate portion 12C may have a flat inclined surface. In this case, the inclination angle of the intermediate portion 12C relative to the bottom surface portion 11 may be, for example, 30° to 90°. Even in this configuration, the side surface portion 12 is continuous with the bottom surface portion 11 and is inclined so as to open outward relative to the bottom surface portion 11, thereby achieving the same advantageous effects as the above configuration. [Explanation of symbols]

[0049] 1...vibration device, 2...piezoelectric part, 3...housing, 5...piezoelectric element, 11...bottom part, 12...side part, 12a...top part, 12b...inner part, 12c...outer surface, 12A...connecting part, 12B...connecting part, 13...flange part, 21...upper base, 22...lower base, 24...long side, 25...short side, 31...first opening, 32...second opening.

Claims

1. a piezoelectric portion including a piezoelectric element; a metal housing that holds the piezoelectric portion, the housing has a bottom surface portion to which the piezoelectric portion is fixed, and a side surface portion provided upright at an edge portion of the bottom surface portion so as to surround the piezoelectric portion, the side surface portion is continuous with the bottom surface portion and is inclined relative to the bottom surface portion so as to open outward from the edge portion, The piezoelectric portion has a rectangular shape in a plan view, the bottom surface portion has a trapezoidal shape in plan view, with sides corresponding to long sides of the piezoelectric portion as upper and lower bases; the upper side of the bottom surface portion is shorter than the long side of the piezoelectric portion, A vibration device in which the lower base of the bottom surface portion is longer than the long side of the piezoelectric portion.

2. The vibration device according to claim 1 , wherein both the inner and outer surfaces of the side surface portion are inclined with respect to the bottom surface portion.

3. a ridge portion of the piezoelectric element and a connection portion between the bottom surface portion and the side surface portion are both curved, The vibration device according to claim 1 or 2, wherein the radius of curvature of the connection portion is larger than the radius of curvature of the ridge portion of the piezoelectric element.

4. A vibration device according to any one of claims 1 to 3, wherein the distance between the lower base of the bottom surface portion and the long side of the piezoelectric portion along the lower base is shorter than the short side of the piezoelectric portion.

5. The vibration device according to any one of claims 1 to 4, wherein a first opening is formed on the lower base side of the bottom surface portion by not providing the side surface portion.

6. The resonation device according to claim 5 , wherein a second opening is formed on the upper side of the bottom surface portion by cutting out a part of the top of the side surface portion.

7. The vibrating device according to claim 6 , wherein the opening area of ​​the first opening is larger than the opening area of ​​the second opening.

8. The vibration device according to any one of claims 1 to 7, wherein an outward flange portion is provided at the top of the side surface portion.

9. The vibration device according to claim 8 , wherein a radius of curvature of a connecting portion between the side surface portion and the flange portion is smaller than a radius of curvature of a connecting portion between the bottom surface portion and the side surface portion.

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