Ultrasonic device

Abstract

The ultrasonic device of the present invention includes: a housing, a piezoelectric element, a sound-absorbing material, and a vibration-proof material. The housing defines an accommodation space. The piezoelectric element is disposed within the accommodation space. The sound-absorbing material is disposed on the main surface of the piezoelectric element and is formed of a foam. The vibration-proof material is disposed around the sound-absorbing material. The sound-absorbing material has a first opposing surface that opposes the main surface. The first opposing surface has an uneven shape in which convex portions and concave portions are alternately continuous and is rougher than the main surface.

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic device. Background Art

[0002] There is known an ultrasonic receiver including: a housing; a piezoelectric vibration element disposed in the housing; a sound-absorbing filling material such as felt disposed on the piezoelectric vibration element; and a sealing insulating resin such as silicone resin for sealing the housing (for example, refer to Japanese Unexamined Patent Application Publication No. 2004-260239). Summary of the Invention

[0003] In an ultrasonic device, further reduction of the reverberation of ultrasonic components is sought. However, it is difficult for the above-described ultrasonic device to sufficiently reduce the reverberation of ultrasonic components.

[0004] An object of one aspect of the present invention is to provide an ultrasonic device that further reduces the reverberation of ultrasonic components.

[0005] An ultrasonic device according to one aspect includes: a housing, a piezoelectric element, a sound-absorbing material, and a vibration-proof material. The housing defines an accommodation space. The piezoelectric element is disposed in the accommodation space. The sound-absorbing material is disposed on a main surface of the piezoelectric element and is formed of a foam. The vibration-proof material is disposed around the sound-absorbing material. The sound-absorbing material has a first opposing surface opposing the main surface. The first opposing surface has an uneven shape in which convex portions and concave portions are alternately continuous, and is rougher than the main surface.

[0006] In the above aspect, the first opposing surface of the sound-absorbing material opposing the piezoelectric element has an uneven shape that is rougher than the surface of the piezoelectric element. Thus, the surface area of the first opposing surface increases, and therefore, the sound-absorbing effect through the sound-absorbing material can be improved. As a result, the reverberation of ultrasonic components can be further reduced.

[0007] In the above aspect, it may be that a plurality of recesses are provided on surfaces of the convex portions and the concave portions of the first opposing surface. In this case, the surface area of the first opposing surface further increases, and therefore, the sound-absorbing effect through the sound-absorbing material can be further improved.

[0008] In the above aspect, it may be that a first space is formed between the piezoelectric element and the first opposing surface. In this case, the reverberation of ultrasonic components is not directly transmitted from the piezoelectric element to the framework of the sound-absorbing material. Thus, the reverberation of ultrasonic components can be further reduced.

[0009] In one of the above-described ways, it may also be provided with: a substrate that is disposed within the accommodation space, opposite to the piezoelectric element with an acoustic absorption material therebetween, and is electrically connected to the piezoelectric element. It may also be that the acoustic absorption material has a second opposite surface opposite to the substrate. It may also be that the second opposite surface has an uneven shape in which convex portions and concave portions are alternately continuous and is rougher than the main surface. In this case, the second opposite surface has an uneven shape that is rougher than the main surface of the piezoelectric element. Therefore, the ultrasonic components are diffusely reflected by the second opposite surface. As a result, the leakage of the ultrasonic components from the second opposite surface is suppressed. Consequently, the reverberation of the ultrasonic components can be further reduced.

[0010] In one of the above-described ways, it may also be that a plurality of recesses are provided on the surfaces of the convex portions and concave portions of the second opposite surface. In this case, the ultrasonic components are further diffusely reflected by the plurality of recesses.

[0011] In one of the above-described ways, it may also be that a second space is formed between the substrate and the second opposite surface. In this case, the reverberation of the ultrasonic components is not directly transmitted from the framework of the acoustic absorption material to the substrate. Thereby, the reverberation of the ultrasonic components can be further reduced.

[0012] In one of the above-described ways, it may also be that the first opposite surface is rougher than the second opposite surface. In this case, compared with the case where the first opposite surface is not rough, the surface area of the first opposite surface increases. Therefore, the sound absorption effect through the acoustic absorption material can be improved.

[0013] In one of the above-described ways, it may also be provided with: a vibration damping material that is disposed on the main surface. It may also be that the acoustic absorption material is disposed such that the convex portions of the first opposite surface are in contact with the vibration damping material. In this case, since the first opposite surface has an uneven shape, even if the convex portions are in contact with the vibration damping material, the sound absorption effect through the acoustic absorption material can be exerted.

[0014] In one of the above-described ways, it may also be that, when viewed from the thickness direction of the piezoelectric element, the piezoelectric element is located inside the outer edge of the acoustic absorption material. In this case, the ultrasonic components are easily absorbed by the acoustic absorption material. Therefore, the reverberation of the ultrasonic components is further reduced.

[0015] In one of the above-described ways, it may also be that, in the thickness direction of the piezoelectric element, the acoustic absorption material protrudes more toward the piezoelectric element side than the vibration damping material. In this case, the surface area of the acoustic absorption material exposed from the vibration damping material increases. Therefore, the reverberation of the ultrasonic components is further reduced.

[0016] In one of the above-described ways, it is also possible that, when viewed from the thickness direction of the piezoelectric element, the first opposing surface has: a first region, which is located on the outer side of the piezoelectric element; and a second region, which is located on the inner side of the first region. The second region is rougher than the first region. In this case, since the second region is rough, the surface area becomes larger, and thus, sound wave absorption can be effectively performed. In addition, since the first region has a sound insulation effect, sound wave transmission to the sleeve and the pin can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a perspective view of an ultrasonic device according to an embodiment.

[0018] Figure 2 is Figure 1 an exploded perspective view of the ultrasonic device.

[0019] Figure 3 is a sectional view taken along line III-III of Figure 1 the ultrasonic device.

[0020] Figure 4 is a sectional view taken along line IV-IV of Figure 1 the ultrasonic device.

[0021] Figure 5 is a top view of the housing and the piezoelectric element.

[0022] Figure 6 is Figure 3 a partial enlarged view of the ultrasonic device.

[0023] Figure 7A and Figure 7B is a top view showing the piezoelectric element.

[0024] Figure 8A and Figure 8B is a schematic diagram showing the energy attenuation of sound passing through the sound-absorbing material.

[0025] Figure 9 is a partial enlarged sectional view of the ultrasonic device according to the first modification.

[0026] Figure 10 is a partial enlarged sectional view of the ultrasonic device according to the second modification.

[0027] Figure 11 is a partial enlarged sectional view of the ultrasonic device according to the third modification.

[0028] Figure 12 is a partial enlarged sectional view of the ultrasonic device according to the fourth modification.

[0029] Figure 13 is a partial enlarged sectional view of the ultrasonic device according to the fifth modification.

[0030] Figure 14 It is a partially enlarged sectional view of the ultrasonic device according to the sixth modification. Detailed implementation mode

[0031] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, in the description, the same reference numerals are used for the same elements or elements having the same function, and repeated descriptions are omitted.

[0032] Refer to Figures 1 to 4 to describe the structure of the ultrasonic device 1 according to the present embodiment. Figure 1 It is a perspective view of the ultrasonic device according to an embodiment. Figure 2 Is Figure 1 Exploded perspective view of the ultrasonic device. Figure 3 Is along Figure 1 Cross-sectional view taken along line III-III. Figure 4 Is along Figure 1 Cross-sectional view taken along line IV-IV.

[0033] As Figures 1 to 4 shown, the ultrasonic device 1 includes: a housing 10, a piezoelectric element 20, a wiring member 30, a plurality of pins 41, 43, a plurality of sleeves 45, 47, a sound-absorbing material 50, a substrate 60, a plurality of pins 65, 67, and a vibration-proof material 70. The housing 10 defines an accommodation space S1. The piezoelectric element 20, the wiring member 30, the plurality of pins 41, 43, the sound-absorbing material 50, the substrate 60, the plurality of pins 65, 67, and the vibration-proof material 70 are arranged in the accommodation space S1. In the present embodiment, the ultrasonic device 1 constitutes an ultrasonic sensor. The ultrasonic device 1 transmits and receives ultrasonic waves, for example.

[0034] The housing 10 has a bottom wall 11 and a side wall 13. The side wall 13 extends in a direction intersecting the bottom wall 11. The bottom wall 11 and the side wall 13 define the accommodation space S1. The direction intersecting the bottom wall 11 may also be, for example, a direction orthogonal to the bottom wall 11. The bottom wall 11 and the side wall 13 are integrally formed. The housing 10 is a bottomed cylindrical member with one end open. The housing 10 is made of aluminum (Al), for example. The housing 10 may also be made of a metal other than Al. The housing 10 may also be made of an aluminum alloy, stainless steel, or copper alloy, for example. The aluminum alloy contains duralumin, for example. The copper alloy contains brass, for example.

[0035] Figure 5 It is a top view of the housing and the piezoelectric element. In Figure 5 the sound-absorbing material 50 is shown by a dashed line. Also as Figure 5As shown, the bottom wall 11 has a bottom surface 12 facing the accommodation space. When observed from a direction intersecting the bottom surface 12, the bottom surface 12 is in a circular shape having a major axis and a minor axis. In the present embodiment, the bottom surface 12 is in an oval shape. On the bottom surface 12, the direction along the major axis and the direction along the minor axis intersect each other. The direction along the major axis and the direction along the minor axis are, for example, orthogonal. The thickness of the bottom wall 11 is, for example, 0.7 mm or more and 1.5 mm or less. In the present embodiment, the thickness of the bottom wall 11 is 0.9 mm.

[0036] Hereinafter, the direction along the major axis of the bottom surface 12 is defined as the X direction, the direction along the minor axis of the bottom surface 12 is defined as the Y direction, and the direction orthogonal to the bottom surface 12 is defined as the Z direction.

[0037] The bottom surface 12 is defined by a pair of straight-shaped edges 12a and a pair of arc-shaped edges 12b. The pair of edges 12a extend in the X direction and are separated in the Y direction. The pair of edges 12a are substantially parallel to each other. The edges 12b connect the ends of the respective edges 12a to each other. The circular shape having a major axis and a minor axis may also be an elliptical shape. The direction intersecting the bottom surface 12 may also be, for example, the direction orthogonal to the bottom surface 12. The direction intersecting the bottom surface 12 may also coincide with the direction intersecting the bottom wall 11.

[0038] The side wall 13 has an inner side surface 14. The bottom surface 12 and the inner side surface 14 constitute the inner surface of the housing 10. On the inner side surface 14, a plurality of stepped portions 15 are formed. In the present embodiment, three stepped portions 15 are formed. One stepped portion 15 extends along one edge 12a. The remaining two stepped portions 15 are provided separately along the other edge 12a. The stepped portions 15 are used for positioning the vibration-proof material 70 relative to the housing 10.

[0039] Figure 6 is Figure 3 a partial enlarged view of. Figure 7A and Figure 7B is a top view showing a piezoelectric element. The piezoelectric element 20 also has a piezoelectric body 21 and a plurality of electrodes 23, 25 as shown in Figure 5 , Figure 6 , Figure 7A and Figure 7B shown. In the present embodiment, the piezoelectric element 20 has two electrodes 23, 25. The piezoelectric element 20 is disposed on the bottom wall 11. The piezoelectric element 20 is fixed to the bottom wall 11 by adhesion, for example.

[0040] The piezoelectric element 21 has a pair of main surfaces 21a and 21b facing each other and at least one side surface 21c. The side surface 21c extends in the direction (Z direction) in which the pair of main surfaces 21a and 21b face each other so as to connect the pair of main surfaces 21a and 21b. The main surface 21b faces the bottom surface 12. The piezoelectric element 20 is disposed on the bottom wall 11 such that the main surface 21b faces the bottom surface 12. The direction in which the pair of main surfaces 21a and 21b face each other is a direction intersecting the bottom wall 11 (bottom surface 12). The direction in which the pair of main surfaces 21a and 21b face each other may also be a direction orthogonal to the bottom wall 11 (bottom surface 12).

[0041] The piezoelectric element 21 has a rectangular parallelepiped shape (rectangular plate shape). The pair of main surfaces 21a and 21b have a rectangular shape. The piezoelectric element 21 has three side surfaces 21d in addition to the side surface 21c. Each side surface 21d also extends in the direction (Z direction) in which the pair of main surfaces 21a and 21b face each other so as to connect the pair of main surfaces 21a and 21b. In the present embodiment, the piezoelectric element 21 has a square shape when viewed from above. The piezoelectric element 21 may also have a disk shape. The "rectangular parallelepiped shape" in the present specification includes the shape of a rectangular parallelepiped in which the corners and edges are chamfered, and the shape of a rectangular parallelepiped in which the corners and edges are rounded.

[0042] The piezoelectric element 21 is made of a piezoelectric ceramic material. The piezoelectric ceramic material includes, for example, PZT [Pb(Zr,Ti)O3], PT (PbTiO3), PLZT [(Pb,La)(Zr,Ti)O3], or barium titanate (BaTiO3). The piezoelectric element 21 is made of, for example, a sintered body of a ceramic green sheet containing the above piezoelectric ceramic material. The thickness of the piezoelectric element 21 is, for example, 150 μm or more and 500 μm or less. In the present embodiment, the thickness of the piezoelectric element 21 is 200 μm.

[0043] The electrode 23 is provided on the main surface 21b, the side surface 21c, and the main surface 21a. The electrode 23 has: a portion 23a located on the main surface 21b, a portion 23b located on the side surface 21c, and a portion 23c located on the main surface 21a. The portion 23a and the portion 23b are connected to each other at a ridge portion between the main surface 21b and the side surface 21c. The portion 23b and the portion 23c are connected to each other at a ridge portion between the main surface 21a and the side surface 21c. Each of the portions 23a, 23b, and 23c is integrally formed. The portion 23a of the electrode 23 is joined to the bottom wall 11 (bottom surface 12).

[0044] When observing from the thickness direction (Z direction) of the piezoelectric element 20 (piezoelectric body 21), the portion 23a of the electrode 23 is separated from the edge portion between the side surface 21d opposite to the side surface 21c and the main surface 21b. The main surface 21b is exposed along the edge portion between the side surface 21d opposite to the side surface 21c and the main surface 21b. The portion 23b of the electrode 23 covers the entire side surface 21c. Each side surface 21d is exposed from the electrode 23.

[0045] The electrode 25 is provided on the main surface 21a. The electrode 25 is only disposed on the main surface 21a. The electrode 25 is separated from the portion 23c of the electrode 23. The main surface 21a is exposed between the portion 23c of the electrode 23 and the electrode 25. When observing from a direction orthogonal to the main surface 21a, the electrode 25 is separated from the edge portion between the side surface 21d opposite to the side surface 21c and the main surface 21a. The main surface 21a is exposed along the edge portion between the side surface 21d opposite to the side surface 21c and the main surface 21a. Each side surface 21d is also exposed from the electrode 25. The piezoelectric body 21 has a region overlapping with the portion 23a of the electrode 23 and the electrode 25 in the Z direction. This region is clamped by the portion 23a of the electrode 23 and the electrode 25 in the Z direction. In the piezoelectric element 20, this region constitutes a piezoelectric active region.

[0046] Each of the electrodes 23 and 25 is in contact with the surface of the piezoelectric body 21. The thickness of each of the electrodes 23 and 25 is 1.5 μm or less. Each of the electrodes 23 and 25 includes, for example, a laminate composed of a chromium (Cr) layer, a nickel-copper alloy (Ni-Cu) layer, and a gold (Au) layer. Each of the electrodes 23 and 25 may also include silver (Ag), titanium (Ti), platinum (Pt), a silver-palladium alloy (Ag-Pd), or a nickel-chromium alloy (Ni-Cr). Each of the electrodes 23 and 25 is formed on the surface of the piezoelectric body 21 by, for example, a sputtering method.

[0047] The piezoelectric element 20 is also as Figure 5 shown, and is disposed on the bottom wall 11 (bottom surface 12) with the side surface 21c along the Y direction. The regions of the main surface 21a exposed from each of the electrodes 23 and 25 extend in the Y direction. In a state where the piezoelectric element 20 is disposed in the housing 10, the electrode 25 and the portion 23c of the electrode 23 are separated in the X direction. In the present embodiment, the direction in which the side surface 21c and the side surface 21d face each other is the X direction. The piezoelectric element 20 is disposed, for example, at approximately the center in the X direction and the Y direction on the bottom surface 12. The piezoelectric body 21 is square in plan view, but the piezoelectric body 21 may also be rectangular in plan view. In this case, the direction along the long side of the piezoelectric body 21 is the long side direction, and the direction along the short side of the piezoelectric body 21 is the short side direction. The piezoelectric element 20 may also be disposed on the bottom wall 11 with the long side direction of the piezoelectric body 21 along the X direction.

[0048] The wiring component 30 is disposed on the main surface 21a of the piezoelectric element 20 (piezoelectric body 21). The wiring component 30 is electrically connected to the piezoelectric element 20. The wiring component 30 is, for example, a flexible printed circuit board (FPC) or a flexible flat cable (FFC). The wiring component 30 has a base body 31 and two leg portions 33, 35.

[0049] The base body 31 is a plate-like component that has substantially the same shape as the bottom surface 12 in a plan view. The base body 31 is smaller than the bottom surface 12 by one circle in a plan view and is disposed separately from the inner side surface 14. The base body 31 also has, as Figure 6 shown, a pair of main surfaces 31a, 31b that face each other in the Z direction. The wiring component 30 is disposed in the accommodation space S1 such that the main surface 31b faces the piezoelectric body 21.

[0050] An opening 31c is formed in the base body 31 to expose a part of the piezoelectric element 20. In the present embodiment, the opening 31c has a rectangular shape. The edge portion of the opening 31c has a pair of linear edge portions 31d that face each other in the X direction and a pair of linear edge portions 31e that face each other in the Y direction. One edge portion 31d covers the entire part 23c of the electrode 23. The other edge portion 31d covers a part of the electrode 25.

[0051] The base body 31 is, for example, a resin layer made of a resin such as a polyimide resin. A plurality of conductor layers (not shown) are disposed in the base body 31. The plurality of conductor layers are bonded to the base body 31. In the present embodiment, two conductor layers are disposed. One conductor layer connects the electrode 23 and the pin 41. The other conductor layer connects the electrode 25 and the pin 43.

[0052] The leg portions 33, 35 are provided on the main surface 31b (see Figure 6 ) and are in contact with the bottom surface 12. When observed from a direction (Z direction) orthogonal to the bottom surface 12, the leg portions 33, 35 are disposed on both sides of the piezoelectric element 20 so as to sandwich the piezoelectric element 20 in the X direction. The leg portions 33, 35 extend in the Y direction along a pair of edges 12b of the bottom surface 12 (see Figure 5 ). The leg portion 33 faces a part 23b (side surface 21c) of the electrode 23. The leg portion 35 faces a side surface 21d that faces the side surface 21c.

[0053] The wiring component 30 is fixed to the bottom wall 11 (bottom surface 12) by insulating hot melt resins 37, 39. The hot melt resin 37 is disposed on the main surface 31b between the leg portion 33 and the part 23b. The hot melt resin 39 is disposed on the main surface 31b between the leg portion 35 and the side surface 21d. The hot melt resins 37, 39 are bonded to the main surface 31b and the bottom surface 12.

[0054] The pin 41 is welded to a conductive layer provided on the base body 31. The pin 41 can also be connected to a conductive layer by a conductive adhesive. The pin 41 is electrically connected to the electrode 23 through a conductor layer. The pin 43 is welded to another conductive layer provided on the base body 31. The pin 43 can also be connected to another conductive layer by a conductive adhesive. The pin 43 is electrically connected to the electrode 25 through another conductor layer.

[0055] The pins 41 and 43 are arranged on the main surface 31a in a state of being separated from each other in the X direction. The pins 41 and 43 extend along the Z direction from the main surface 31a. In the present embodiment, the pins 41 and 43 have the same shape as each other. Each of the pins 41 and 43 is made of, for example, metal. Each of the pins 41 and 43 is made of, for example, brass. A plating layer (not shown) may be formed on the surface of each of the pins 41 and 43. The plating layer can be formed by nickel plating and tin plating, for example. In this case, the plating layer has a double-layer structure.

[0056] The pin 41 is held by the sleeve 45. The pin 43 is held by the sleeve 47. Each of the sleeves 45 and 47 is a cylindrical member having flanges at both ends. In the present embodiment, the sleeves 45 and 47 have the same shape as each other. Each of the sleeves 45 and 47 is made of resin. Each of the sleeves 45 and 47 is made of, for example, phosphor-deoxidized copper (PDC), or a metal such as brass. When the sleeves 45 and 47 are made of metal, since not only the pins 41 and 43 but also the sleeves 45 and 47 can be joined to the conductive layer of the wiring component 30, the connection reliability is increased. Each of the sleeves 45 and 47 can also be made of PEEK (polyetheretherketone) resin, polybutylene terephthalate resin (PBT resin), or polyphenylene sulfide (PPS) resin.

[0057] The flanges on one end side of each of the sleeves 45 and 47 are joined to the main surface 31a. When viewed from the axial direction (Z direction), the sleeve 45 is arranged at a position overlapping the leg portion 33. When viewed from the axial direction (Z direction), the sleeve 47 is arranged at a position overlapping the leg portion 35. The axial length of each of the sleeves 45 and 47 is shorter than the axial length of each of the pins 41 and 43. Each of the pins 41 and 43 protrudes from each of the sleeves 45 and 47.

[0058] The sound-absorbing material 50 is arranged on the main surface 21a of the piezoelectric element 20 (piezoelectric body 21). The sound-absorbing material 50 is arranged between the pins 41 and 43, separated from the pins 41 and 43. The sound-absorbing material 50 is arranged in the accommodation space S1. The sound-absorbing material 50 has, for example, a rectangular parallelepiped shape. The sound-absorbing material 50 has a pair of main surfaces 50a and 50b facing each other in the Z direction, a pair of side surfaces 50c facing each other in the X direction, and a pair of side surfaces 50d facing each other in the Y direction.

[0059] The main surface 50a (second opposite surface) faces the substrate 60. The main surface 50b (first opposite surface) faces the main surface 21a of the piezoelectric element 20 (piezoelectric body 21). In the present embodiment, each of the main surfaces 50a and 50b has a rectangular shape with a pair of long sides and a pair of short sides. The long sides of each of the main surfaces 50a and 50b extend in the X direction. The short sides of each of the main surfaces 50a and 50b extend in the Y direction. Each side surface 50c faces the pins 41 and 43. Each side surface 50c is separated from the pins 41 and 43. The two end portions of each side surface 50c in the Y direction are in contact with the vibration-proof material 70. Each side surface 50d is in contact with the vibration-proof material 70.

[0060] The sound-absorbing material 50 also, as Figure 5 shown, overlaps the entire piezoelectric element 20 when viewed from the thickness direction (Z direction) of the piezoelectric element 20. That is, when viewed from the Z direction, the piezoelectric element 20 is located inside the outer edge 51 of the sound-absorbing material 50. When viewed from the Z direction, the piezoelectric element 20 is located approximately at the center in the X direction and the Y direction of the sound-absorbing material 50.

[0061] The main surface 50b has an uneven shape in which convex portions 52 and concave portions 53 are alternately continuous, and is rougher than the main surface 21a. The entire main surface 50b has an uneven shape. The height of the convex portion 52 (also referred to as the depth of the concave portion 53) is, for example, 0.5 mm or more and 2 mm or less. Specifically, the height of the convex portion 52 is the height from the bottom of the concave portion 53 to the top of the convex portion 52. The period (pitch) of the uneven shape is, for example, 0.5 mm or more and 1 mm or less. Specifically, the period of the uneven shape is the distance between adjacent convex portions 52, or the distance between adjacent concave portions 53. The period of the uneven shape is, for example, the average value of the distance between adjacent convex portions 52, or the distance between adjacent concave portions 53. The uneven shape of the main surface 50b is formed, for example, by die molding. In the present embodiment, the main surface 50a, the pair of side surfaces 50c, and the pair of side surfaces 50d of the sound-absorbing material 50 do not exhibit the uneven shape like the main surface 50b.

[0062] The sound-absorbing material 50 is separated from the piezoelectric element 20. The sound-absorbing material 50 is also separated from the wiring component 30. The distance in the Z direction between the convex portion 52 of the sound-absorbing material 50 and the piezoelectric element 20 is, for example, 0.5 mm or more and 2 mm or less. A space S2 is formed between the piezoelectric element 20 and the main surface 50b of the sound-absorbing material 50. The space S2 is a part of the accommodation space S1. The space S2 includes the space within the concave portion 53. The thickness of the space S2 is, for example, the maximum value of the distance in the Z direction between the piezoelectric element 20 and the main surface 50b. The thickness of the space S2 is, for example, the distance between the piezoelectric element 20 and the bottom of the concave portion 53. The thickness of the space S2 is, for example, 1 mm or more and 4 mm or less. The sound-absorbing material 50 may also be arranged such that the convex portion 52 is in contact with the piezoelectric element 20. In this case, since the main surface 50b also has an uneven shape, a space S2 is formed as the space within the concave portion 53 between the piezoelectric element 20 and the sound-absorbing material 50 (main surface 50b).

[0063] The sound-absorbing material 50 is composed of, for example, a foam (bubble structure body) with a thermoplastic resin as the main body. The thermoplastic resin contains, for example, ethylene-propylene-diene rubber (EPDM). As Figure 6 shown, the sound-absorbing material 50 is composed of a foam containing continuous bubbles 54. The continuous bubbles 54 are formed by bubbles being continuous with each other. In the continuous bubbles 54, the bubbles are connected to each other and are three-dimensionally continuous. The continuous bubbles 54 are continuous not only in the Figure 4 shown cross-section but also in the direction intersecting with this cross-section. The sound-absorbing material 50 may also contain independent bubbles in addition to the continuous bubbles 54.

[0064] On the surfaces of the convex portion 52 and the concave portion 53, a plurality of depressions 55 corresponding to the shape of the continuous bubbles 54 are provided. The plurality of depressions 55 are formed by the inner surfaces of the continuous bubbles 54 exposed on the surfaces of the convex portion 52 and the concave portion 53. The plurality of depressions 55 may also include depressions connected to the continuous bubbles 54 inside the sound-absorbing material 50. The plurality of depressions 55 may also include depressions corresponding to the shape of the independent bubbles.

[0065] In the present embodiment, a plurality of depressions 55 are provided on the entire surface of the sound-absorbing material 50. That is, a plurality of depressions 55 are also provided on the main surface 50a, the pair of side surfaces 50c, and the pair of side surfaces 50d. The depth of the depression 55 is shallower than the depth of the concave portion 53. The depth of the depression 55 is, for example, 0.1 mm or more and 0.5 mm or less. The period (pitch) of the depression 55 is smaller than the period (pitch) of the uneven shape of the convex portion 52 and the concave portion 53. The period of the depression 55 is, for example, the distance between adjacent depressions 55. The period of the depression 55 is, for example, the average value of the distances between adjacent depressions 55.

[0066] The cross-sectional shape of the main surface 50b is formed by the synthesis of a small roughness curve based on the recess 55 and a large roughness curve based on the uneven shape of the convex portion 52 and the concave portion 53. That is, if the cross-sectional curve of the main surface 50b is separated by a period (wavelength) or frequency, two roughness curves are obtained. The large roughness curve based on the uneven shape of the convex portion 52 and the concave portion 53 corresponds to the waviness curve.

[0067] Figure 8A and Figure 8B is a schematic diagram showing the energy attenuation of sound passing through the sound-absorbing material. In the energy attenuation of sound passing through the sound-absorbing material 50, there is energy attenuation of airborne sound and energy attenuation of structure-borne sound. In Figure 8A the energy attenuation of airborne sound is schematically shown. As Figure 8A shown, when the sound wave W passes through the continuous bubbles 54 or the independent bubbles of the sound-absorbing material, the energy of the sound wave W is attenuated by the friction (or viscosity) of the air.

[0068] In Figure 8B the energy attenuation of structure-borne sound is schematically shown. As Figure 8B shown, when the sound wave W propagates in the skeleton 56 of the sound-absorbing material, the energy of the sound wave W is attenuated by the skeleton 56. The energy attenuation of airborne sound is greater than the energy attenuation of structure-borne sound. In the continuous bubbles 54, the air passage is longer than that of the independent bubbles, so the energy attenuation of airborne sound is effectively carried out. In addition, Figure 8A and Figure 8B the continuous bubbles 54 shown are continuous in the direction intersecting the cross-section shown in Figure 8A and Figure 8B shown.

[0069] The substrate 60 is disposed opposite to the piezoelectric element 20 with the sound-absorbing material 50 interposed therebetween. The substrate 60 is disposed on the main surface 50a. The substrate 60 is disposed within the accommodation space S1. The substrate 60 is a plate-like member. The substrate 60 has a pair of main surfaces 60a and 60b that face each other in the Z direction. The main surface 60b faces the main surface 50a.

[0070] The substrate 60 is separated from the sound-absorbing material 50. A space S3 is formed between the substrate 60 (main surface 60b) and the sound-absorbing material 50 (main surface 50a). The space S3 is a part of the accommodation space S1. The space S3 is defined by the substrate 60, the sound-absorbing material 50, and the vibration-proof material 70. The thickness of the space S3 is, for example, the maximum value of the distance in the Z direction between the substrate 60 (main surface 60b) and the main surface 50a. The thickness of the space S3 is thinner than the thickness of the space S2. The thickness of the space S3 is, for example, 0.2 mm or more and 0.45 mm or less. That is, the substrate 60 and the sound-absorbing material 50 are separated from each other by 0.2 mm or more and 0.45 mm or less in the Z direction. In addition, the space S3 may not be formed.

[0071] Each of the main surfaces 60a and 60b has an oblong shape. The major axis direction of each of the main surfaces 60a and 60b is along the X direction. The minor axis direction of each of the main surfaces 60a and 60b is along the Y direction. A pair of edges in the major axis direction of each of the main surfaces 60a and 60b are bent in a manner of expanding outward and are in an arc shape. In the substrate 60, there are through-holes 61 and 63 through which pins 41 and 43 are inserted. The through-holes 61 and 63 are formed at both ends in the X direction of the substrate 60 and are circular in shape. A pair of edges in the major axis direction of each of the main surfaces 60a and 60b are bent along the through-holes 61 and 63.

[0072] The substrate 60 is electrically connected to the piezoelectric element 20. The substrate 60 is constituted by, for example, a glass epoxy substrate. In the substrate 60, a plurality of conductor layers (not shown) are disposed. The plurality of conductor layers are bonded to the substrate 60. In the present embodiment, two conductor layers are disposed. One conductor layer connects the pin 41 and the pin 65. The other conductor layer connects the pin 43 and the pin 67.

[0073] The pins 41 and 65 are soldered to one conductive layer of the substrate 60. The pins 41 and 65 may also be connected to one conductive layer of the substrate 60 by a conductive adhesive. The pins 41 and 65 are electrically connected to each other through one conductor layer of the substrate 60. The pins 43 and 67 are soldered to the other conductive layer of the substrate 60. The pins 43 and 67 may also be connected to the other conductive layer of the substrate 60 by a conductive adhesive. The pins 43 and 67 are electrically connected to each other through the other conductor layer of the substrate 60.

[0074] The pins 65 and 67 are disposed on the main surface 60a in a state of being separated from each other in the X direction. The pins 65 and 67 extend from the main surface 60a along the Z direction and penetrate through the vibration-proof material 70. The pins 65 and 67 are disposed between the pins 41 and 43 in the X direction. In the present embodiment, the pins 65 and 67 have the same shape as each other.

[0075] The pins 65 and 67 are made of, for example, metal. The pins 65 and 67 are made of, for example, brass. A plating layer (not shown) may be formed on the surface of each of the pins 65 and 67. The plating layer may be formed by, for example, nickel plating and tin plating. In this case, the plating layer has a double-layer structure.

[0076] The vibration-proof material 70 is disposed in contact with the inner surface (inner side surface 14) of the housing 10 and suppresses the vibration of the housing 10. The vibration-proof material 70 is disposed around the sound-absorbing material 50. The vibration-proof material 70 has a surface 70a opposite to the bottom wall 11 of the housing 10. When observed from the thickness direction (Z direction) of the piezoelectric element 20, the surface 70a is adjacent to the main surface 50b.

[0077] The vibration-proof material 70 has a lid body 71 and a frame body 73. The lid body 71 closes the opening of the housing 10 in a state where the piezoelectric element 20, the wiring component 30, the pins 41, 43, the sleeves 45, 47, the sound-absorbing material 50, and the substrate 60 are accommodated in the housing 10. The lid body 71 closes the accommodation space S1. The front ends of the respective pins 65, 67 project from the lid body 71.

[0078] As Figure 4 shown, on the inner surface 71a of the lid body 71, there is provided a recess 71b in which the substrate 60 is disposed. The substrate 60 is disposed in the recess 71b in a state where the main surface 60a faces the bottom surface of the recess 71b. The bottom surface of the recess 71b has a shape corresponding to the main surface 60a. The bottom surface of the recess 71b has the same shape as the main surface 60a. When assembling the ultrasonic device 1, for example, after disposing the substrate 60 on the bottom surface of the recess 71b, the sound-absorbing material 50 is disposed on the inner surface 71a. The depth of the recess 71b is deeper than the thickness of the substrate 60, and thus, a space S3 is formed between the substrate 60 and the sound-absorbing material 50.

[0079] On the bottom surface of the recess 71b, there are provided a recess 71c for accommodating the pin 41 and a recess 71d for accommodating the pin 43. The recesses 71c, 71d are, for example, circular in cross section. The diameters of the recesses 71c, 71d are longer than the diameters of the pins 41, 43. The inner surfaces of the recesses 71c, 71d are separated from the pins 41, 43. The recesses 71c, 71d are provided at both ends in the X direction of the bottom surface of the recess 71b.

[0080] The frame body 73 extends in a direction crossing the lid body 71. The direction crossing the lid body 71 may also be, for example, a direction orthogonal to the lid body 71. The lid body 71 and the frame body 73 are integrally formed. The vibration-proof material 70 is a cylindrical member whose one axial end is blocked and the other end (corresponding to the surface 70a) is open. The vibration-proof material 70 is inserted into the interior of the housing 10. The vibration-proof material 70 is press-fitted into the interior of the housing 10. The frame body 73 extends along the inner side of the housing 10 from the lid body 71 in the Z direction. The frame body 73 is separated from the bottom surface 12. The frame body 73 abuts against the inner side surface 14 of the housing 10.

[0081] The frame body 73 surrounds the periphery of the sound-absorbing material 50. The sound-absorbing material 50 projects more toward the piezoelectric element 20 side than the vibration-proof material 70 (frame body 73) in the thickness direction (Z direction) of the piezoelectric element 20. The distance in the Z direction between the frame body 73 and the piezoelectric element 20 is longer than the distance in the Z direction between the sound-absorbing material 50 and the piezoelectric element 20 (the thickness of the space S2).

[0082] The housing 73 has a pair of side portions 75 and a pair of side portions 77. The pair of side portions 75 face each other in the X direction with the sound-absorbing material 50 therebetween. The pair of side portions 77 face each other in the Y direction with the sound-absorbing material 50 therebetween. Each side portion 75 faces each side surface 50c of the sound-absorbing material 50. Each side portion 75 is separated from the sound-absorbing material 50.

[0083] The pair of side portions 77 hold the sound-absorbing material 50 therebetween. The sound-absorbing material 50 is inserted between the pair of side portions 77. The pair of side portions 77 compress the sound-absorbing material 50. The sound-absorbing material 50 presses the pair of side portions 77 by the repulsive force against the compression. Each side portion 77 is in contact with each side surface 50d of the sound-absorbing material 50.

[0084] The vibration-proof material 70 also has a plurality of protruding portions 79 extending from the lid body 71 toward the inner side surface 14 side. The protruding portions 79 are provided at positions corresponding to the step portion 15 of the housing 10 in the lid body 71. The protruding portions 79 are disposed at the corresponding step portion 15. The vibration-proof material 70 is positioned relative to the housing 10 by engaging the protruding portions 79 with the step portion 15.

[0085] The vibration-proof material 70 is an elastic body and suppresses reverberation by its elasticity. The vibration-proof material 70 is made of resin. The vibration-proof material 70 is a non-foamed body and has a density higher than that of the sound-absorbing material 50. The vibration-proof material 70 is made of, for example, silicone rubber. The vibration-proof material 70 is made of, for example, RTV (Room Temperature Vulcanizing) silicone rubber.

[0086] The ultrasonic sensor transmits an output wave and receives the output wave bounced back from the inspection object. When the ultrasonic sensor approaches the inspection object and the distance from the ultrasonic sensor to the inspection object is small, the voltage of the reverberation component generated when transmitting the output wave and the received voltage of the output wave bounced back from the inspection object interfere with each other. Thus, it is sometimes difficult to detect the received voltage in the ultrasonic sensor.

[0087] In the ultrasonic device 1, the main surface 50b of the sound-absorbing material 50 facing the piezoelectric element 20 has an uneven shape that is rougher than the main surface 21a. Thus, the surface area of the main surface 50b increases. The ultrasonic components are absorbed by the sound-absorbing material 50 from the main surface 50b. At this time, the larger the surface area of the main surface 50b, the easier it is for the ultrasonic components to be absorbed. Therefore, in the ultrasonic device 1, the sound-absorbing effect by the sound-absorbing material 50 can be improved. As a result, the reverberation of the ultrasonic components can be further reduced.

[0088] In the ultrasonic device 1, a plurality of recesses 55 corresponding to the shape of the continuous bubbles 54 are provided on the surfaces of the convex portions 52 and the concave portions 53 of the main surface 50b. Thus, the surface area of the main surface 50b further increases, and therefore, the sound-absorbing effect by the sound-absorbing material 50 can be further improved.

[0089] In the ultrasonic device 1, a space S2 is formed between the piezoelectric element 20 and the sound-absorbing material 50. Therefore, the reverberation of the ultrasonic component does not directly propagate from the piezoelectric element 20 to the skeleton 56 of the sound-absorbing material 50. Thus, the reverberation of the ultrasonic component can be further reduced.

[0090] As described above, the energy of the sound wave W is also attenuated by the skeleton 56, but the energy attenuation of the sound propagated through the solid is smaller than that of the sound propagated through the air. Therefore, compared with the case where the piezoelectric element 20 and the sound-absorbing material 50 are in contact with each other, the reverberation of the ultrasonic component is more easily reduced when the piezoelectric element 20 and the sound-absorbing material 50 are separated from each other.

[0091] In the case where the piezoelectric element 20 and the sound-absorbing material 50 are in contact with each other, as a result of the piezoelectric element 20 being overly restricted, the vibration characteristics of the piezoelectric element 20 may be degraded. In the present embodiment, the piezoelectric element 20 and the sound-absorbing material 50 are separated from each other, so the piezoelectric element 20 is not overly restricted in this way. Therefore, good vibration characteristics can be obtained. Further, in the ultrasonic device 1, the convex portion 52 may also be in contact with the piezoelectric element 20. Since the main surface 50b has an uneven shape, even when the convex portion 52 is in contact with the piezoelectric element 20, the concave portion 53 and the recess 55 of the main surface 50b remain in a state of not being in contact with the piezoelectric element 20. Thus, the sound-absorbing effect of the sound-absorbing material 50 is exerted. In this way, the space S2 can be ensured between the piezoelectric element 20 and the sound-absorbing material 50, and the interval between the piezoelectric element 20 and the sound-absorbing material 50 can be reduced. Therefore, space saving can be achieved.

[0092] In the ultrasonic device 1, a space S3 is formed between the substrate 60 and the sound-absorbing material 50. Therefore, the reverberation of the ultrasonic component does not directly propagate from the skeleton 56 of the sound-absorbing material 50 to the substrate 60. Thus, the reverberation of the ultrasonic component can be further reduced.

[0093] In the ultrasonic device 1, the main surface 50b is rougher than the main surface 50a. Therefore, compared with the case where the main surface 50b is not rough, the surface area of the main surface 50b increases, and thus the sound-absorbing effect of the sound-absorbing material 50 can be improved.

[0094] In the ultrasonic device 1, when viewed from the thickness direction (Z direction) of the piezoelectric element 20, the piezoelectric element 20 is located inside the outer edge 51 of the sound-absorbing material 50. In this way, the sound-absorbing material 50 is arranged so as to cover the whole of the piezoelectric element 20. Therefore, the ultrasonic component is easily absorbed by the sound-absorbing material 50. Thus, the reverberation of the ultrasonic component is further reduced.

[0095] In the ultrasonic device 1, in the thickness direction (Z direction) of the piezoelectric element 20, the sound-absorbing material 50 protrudes more toward the piezoelectric element 20 than the vibration-proof material 70. Therefore, the surface area of the sound-absorbing material 50 exposed from the vibration-proof material 70 increases, and thus, the sound-absorbing effect through the sound-absorbing material 50 can be improved. As a result, the reverberation of the ultrasonic component is further reduced.

[0096] As described above, the embodiments of the present invention have been described, but the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof.

[0097] Figure 9 is a cross-sectional view of the ultrasonic device according to the first modification. As Figure 9 shown, the ultrasonic device 1A is different from the ultrasonic device 1 (see Figure 3 ) in that the sound-absorbing material 50A is provided instead of the sound-absorbing material 50 (see Figure 3 ). In the sound-absorbing material 50A, when viewed from the thickness direction (Z direction) of the piezoelectric element 20, the main surface 50b has a first region R1 located outside the piezoelectric element 20 and a second region R2 located inside the first region R1. When viewed from the Z direction, the second region R2 is the same as or larger than the piezoelectric element 20 and overlaps the entire piezoelectric element 20.

[0098] The first region R1 is rougher than the second region R2. Here, the height of the convex portion 52 (or the depth of the concave portion 53) is the same between the first region R1 and the second region R2. The period (pitch) of the concavo-convex shape of the first region R1 is smaller than the period (pitch) of the concavo-convex shape of the second region R2. The number of convex portions 52 (or concave portions 53) per unit area of the first region R1 when viewed from the relative direction (Z direction) of the main surfaces 50a and 50b is larger than the number of convex portions 52 (or concave portions 53) per unit area of the second region R2.

[0099] Figure 10 is a cross-sectional view of the ultrasonic device according to the second modification. As Figure 10 shown, the ultrasonic device 1B is different from the ultrasonic device 1 (see Figure 3 ) in that the sound-absorbing material 50B is provided instead of the sound-absorbing material 50 (see Figure 3 ). In the sound-absorbing material 50B, when viewed from the thickness direction (Z direction) of the piezoelectric element 20, the main surface 50b has a first region R1 located outside the piezoelectric element 20 and a second region R2 located inside the first region R1. When viewed from the Z direction, the second region R2 is the same as or larger than the piezoelectric element 20 and overlaps the entire piezoelectric element 20.

[0100] The second region R2 is rougher than the first region R1. Here, the height of the convex portion 52 (or the depth of the concave portion 53) is the same between the first region R1 and the second region R2. The period (pitch) of the concavo-convex shape in the second region R2 is smaller than the period (pitch) of the concavo-convex shape in the first region R1. The number of convex portions 52 (or the number of concave portions 53) per unit area of the first region R1 as observed from the relative direction (Z direction) of the main surfaces 50a and 50b is smaller than the number of convex portions 52 (or the number of concave portions 53) per unit area of the second region R2.

[0101] Also in the ultrasonic devices 1A and 1B, the main surface 50b has a concavo-convex shape in which the convex portions 52 and the concave portions 53 are alternately continuous, and is rougher than the main surface 21a. Therefore, the same effect as that of the ultrasonic device 1 can be obtained. In the ultrasonic device 1A, the first region R1 is rougher than the second region R2. Therefore, the first region R1 absorbs ultrasonic components more easily than the second region R2. In the ultrasonic device 1B, the second region R2 is rougher than the first region R1. Therefore, the second region R2 absorbs ultrasonic components more easily than the first region R1.

[0102] A part of the ultrasonic components absorbed by the sound-absorbing material 50 is reflected by the inner surface of the vibration-proof material 70 and leaks out of the sound-absorbing material 50 from the main surface 50b. At this time, the rougher the main surface 50b is, the more the ultrasonic components are diffusely reflected by the main surface 50b, and it is difficult to leak out of the sound-absorbing material 50.

[0103] In the ultrasonic device 1A, since the second region R2 is rougher than the first region R1, leakage of ultrasonic components from the second region R2 is further suppressed. In the ultrasonic device 1B, since the first region R1 is rougher than the second region R2, leakage of ultrasonic components from the first region R1 is further suppressed.

[0104] In the ultrasonic device 1A, even if it is assumed that the sound-absorbing material 50 is in contact with the piezoelectric element 20, since the contact area is small, the load on the piezoelectric element 20 is also small. In addition, since the first region R1 is rough and the surface area becomes larger, sound wave absorption can be effectively performed. In the ultrasonic device 1B, since the second region R2 is rough and the surface area becomes larger, sound wave absorption can be effectively performed. In addition, since there is a sound insulation effect in the first region R1, sound wave transmission to the sleeves 45, 47 and the pins 41, 43 can be prevented.

[0105] Figure 11 It is a cross-sectional view of the ultrasonic device according to the third modified example. As Figure 11 shown, the ultrasonic device 1C is different from the ultrasonic device 1 (refer to Figure 3 ) in that it includes a sound-absorbing material 50C instead of the sound-absorbing material 50 (refer to Figure 3) Different. In the sound-absorbing material 50C, not only the main surface 50b but also the main surface 50a has a concavo-convex shape in which convex portions 52 and concave portions 53 are continuous, and is rougher than the main surface 21a. The entire main surface 50a has a concavo-convex shape. Although not shown, in the sound-absorbing material 50C, a plurality of depressions 55 corresponding to the shape of the continuous bubbles 54 are also provided on the surfaces of the convex portions 52 and concave portions 53 of the main surface 50a.

[0106] The concavo-convex shape of the main surface 50a is the same as that of the main surface 50b. That is, the height and the period (pitch) of the concavo-convex shape of the convex portion 52 of the main surface 50a are the same as those of the convex portion 52 of the main surface 50b. The number of convex portions 52 (or the number of concave portions 53) per unit area observed from the relative direction (Z direction) of the main surfaces 50a and 50b is the same for the main surfaces 50a and 50b.

[0107] The substrate 60 is separated from the sound-absorbing material 50C. The distance in the Z direction between the convex portion 52 of the main surface 50a and the substrate 60 is, for example, 0.5 mm or more and 2 mm or less. The space S3 includes the space inside the concave portion 53. The sound-absorbing material 50C may also be arranged in such a manner that the convex portion 52 is in contact with the substrate 60. Even in this case, since the main surface 50a has a concavo-convex shape, a space S3 is formed as the space inside the concave portion 53 between the substrate 60 (main surface 60b) and the sound-absorbing material 50 (main surface 50a).

[0108] Figure 12 is a cross-sectional view of the ultrasonic device according to the fourth modification example. As Figure 12 shown, the ultrasonic device 1D is different from the ultrasonic device 1C (see Figure 11 ) in that the sound-absorbing material 50D is provided instead of the sound-absorbing material 50C (see Figure 11 ). In the sound-absorbing material 50D, the main surface 50a is rougher than the main surface 50b. The concavo-convex shape of the main surface 50a is different from that of the main surface 50b. The height of the convex portion 52 of the main surface 50a is the same for the main surfaces 50a and 50b. The period (pitch) of the concavo-convex shape of the main surface 50a is smaller than the period (pitch) of the concavo-convex shape of the main surface 50b. The number of convex portions 52 (or the number of concave portions 53) of the main surface 50a per unit area observed from the relative direction (Z direction) of the main surfaces 50a and 50b is larger than the number of convex portions 52 (or the number of concave portions 53) of the main surface 50b per unit area.

[0109] Figure 13 is a cross-sectional view of the ultrasonic device according to the fifth modification example. As Figure 13 shown, the ultrasonic device 1E is different from the ultrasonic device 1C (see Figure 11 ) in that the sound-absorbing material 50E is provided instead of the sound-absorbing material 50C (see Figure 11)They are different. In the sound-absorbing material 50E, the main surface 50b is rougher than the main surface 50a. The concavo-convex shape of the main surface 50a is different from that of the main surface 50b. The height of the convex portion 52 of the main surface 50a is the same between the main surface 50a and the main surface 50b. The period (pitch) of the concavo-convex shape of the main surface 50a is larger than the period (pitch) of the concavo-convex shape of the main surface 50b. The number of convex portions 52 (or concave portions 53) of the main surface 50a per unit area observed from the relative direction (Z direction) of the main surfaces 50a and 50b is smaller than the number of convex portions 52 (or concave portions 53) of the main surface 50b per unit area.

[0110] Also in the ultrasonic devices 1C, 1D, and 1E, the main surface 50b has a concavo-convex shape in which the convex portions 52 and the concave portions 53 are alternately continuous, and is rougher than the main surface 21a. Therefore, the same effect as that of the ultrasonic device 1 can be obtained. In the ultrasonic devices 1C, 1D, and 1E, the main surface 50a also has a concavo-convex shape that is rougher than the main surface 21a. Therefore, the ultrasonic components are diffusely reflected by the main surface 50a. As a result, the leakage of the ultrasonic components from the main surface 50a to the outside is suppressed. As a result, the reverberation of the ultrasonic components can be further reduced. On the surfaces of the convex portions 52 and the concave portions 53 of the main surface 50a, a plurality of depressions 55 corresponding to the shape of the continuous bubbles 54 are also provided. Therefore, the ultrasonic components are further diffusely reflected by the plurality of depressions 55. Since the main surface 50a has a concavo-convex shape, a space S3 is easily formed between the substrate 60 and the sound-absorbing material 50.

[0111] In the ultrasonic device 1D, the main surface 50a is rougher than the main surface 50b. Therefore, compared with the case where the main surface 50a is not rougher than the main surface 50b, since the ultrasonic components are diffusely reflected by the main surface 50a, the leakage of the ultrasonic components from the main surface 50a to the outside is further suppressed.

[0112] In the ultrasonic device 1E, the main surface 50b is rougher than the main surface 50a. Therefore, compared with the case where the main surface 50b is not rougher than the main surface 50a, since the surface area of the main surface 50b increases, the sound absorption effect through the sound-absorbing material 50 can be improved.

[0113] Figure 14 It is a cross-sectional view of the ultrasonic device according to the sixth modified example. As Figure 14 shown, the ultrasonic device 1F is different from the ultrasonic device 1 (refer to Figure 3)They are different. The vibration damping material 40 is disposed on the piezoelectric element 20. The vibration damping material 40 is disposed (coated) on the electrode 25. The vibration damping material 40 is disposed within the opening 31c of the wiring component 30. When viewed from the thickness direction (Z direction) of the piezoelectric element 20, the vibration damping material 40 is separated from the wiring component 30. The vibration damping material 40 does not contact the inner side surface of the opening 31c. The thickness of the vibration damping material 40 is the same as the thickness of the base 31 of the wiring component 30. The vibration damping material 40 is, for example, an elastomer such as rubber. The sound absorbing material 50 is disposed in such a manner that the convex portion 52 of the main surface 50b contacts the vibration damping material 40 and the wiring component 30.

[0114] Also in the ultrasonic device 1F, the main surface 50b has an uneven shape in which the convex portions 52 and the concave portions 53 are alternately continuous, and is rougher than the main surface 21a. Therefore, the same effect as that of the ultrasonic device 1 can be obtained. Since the ultrasonic device 1F is provided with the vibration damping material 40, the reverberation of ultrasonic components is further suppressed. Since the main surface 50b has an uneven shape, even if the convex portion 52 contacts the vibration damping material 40, the concave portion 53 and the recess 55 of the main surface 50b remain in a state of not contacting the vibration damping material 40. Therefore, the sound absorption effect by the sound absorbing material 50 is exerted. In this way, a space S2 can be ensured between the vibration damping material 40 and the sound absorbing material 50, and the interval between the vibration damping material 40 and the sound absorbing material 50 can be reduced, so that space saving can be achieved.

[0115] The ultrasonic devices 1, 1A, 1B, 1C, 1D, 1E, 1F may also only transmit ultrasonic waves. The ultrasonic device 1 may also only receive ultrasonic waves.

[0116] The piezoelectric element 20 may also have one or more internal electrodes disposed within the piezoelectric body 21. In this case, the piezoelectric body 21 may have a plurality of piezoelectric layers, and the internal electrodes and the piezoelectric layers may be alternately disposed.

[0117] In the thickness direction (Z direction) of the piezoelectric element 20, the sound absorbing material 50 may be more recessed toward the opposite side of the piezoelectric element 20 than the vibration damping material 70. The sound absorbing material 50 may be disposed in such a manner that the front end of the convex portion 52 of the main surface 50b is located in the same plane as the front end in the Z direction of the vibration damping material 70.

Claims

1. An ultrasonic device, wherein, Comprising: A housing that defines an accommodation space; A piezoelectric element disposed within the accommodation space; A sound-absorbing material disposed on the main surface of the piezoelectric element and composed of a foam; And A vibration-proof material disposed around the sound-absorbing material, The sound-absorbing material has a first opposing surface opposite to the main surface, The first opposing surface has an uneven shape with convex and concave portions alternating continuously and is rougher than the main surface, The vibration-proof material is separated from the bottom surface of the housing, Further comprising: a damping material disposed on the main surface, The sound-absorbing material is disposed such that the convex portions of the first opposing surface are in contact with the damping material.

2. The ultrasonic device according to claim 1, wherein, On the surfaces of the convex and concave portions of the first opposing surface, a plurality of depressions are provided.

3. The ultrasonic device according to claim 1, wherein, A first space is formed between the piezoelectric element and the first opposing surface.

4. The ultrasonic device according to claim 2, wherein, A first space is formed between the piezoelectric element and the first opposing surface.

5. The ultrasonic device according to any one of claims 1 to 4, wherein, Further comprising: a substrate disposed within the accommodation space, opposite to the piezoelectric element with the sound-absorbing material therebetween and electrically connected to the piezoelectric element, The sound-absorbing material has a second opposing surface opposite to the substrate, The second opposing surface has an uneven shape with convex and concave portions alternating continuously and is rougher than the main surface.

6. The ultrasonic device according to claim 5, wherein, On the surfaces of the convex and concave portions of the second opposing surface, a plurality of depressions are provided.

7. The ultrasonic device according to claim 5, wherein, A second space is formed between the substrate and the second opposing surface.

8. The ultrasonic device according to claim 6, wherein, A second space is formed between the substrate and the second opposing surface.

9. The ultrasonic device according to claim 5, wherein, The first opposing surface is rougher than the second opposing surface.

10. The ultrasonic device according to claim 6, wherein, The first opposing surface is rougher than the second opposing surface.

11. The ultrasonic device according to claim 7, wherein, The first opposing surface is rougher than the second opposing surface.

12. The ultrasonic device according to claim 8, wherein, The first opposing surface is rougher than the second opposing surface.

13. The ultrasonic device according to any one of claims 1 to 4, wherein, Viewed from the thickness direction of the piezoelectric element, the piezoelectric element is located inside the outer edge of the sound-absorbing material.

14. The ultrasonic device according to any one of claims 1 to 4, wherein, In the thickness direction of the piezoelectric element, the sound-absorbing material protrudes more toward the piezoelectric element side than the vibration-proof material.

15. The ultrasonic device according to any one of claims 1 to 4, wherein, When viewed in the thickness direction of the piezoelectric element, the first opposite surface has: a first region located on the outer side of the piezoelectric element; and a second region located on the inner side of the first region. The second region is rougher than the first region.

Images