Ultrasonic Transducer

Abstract

To provide a technique capable of reducing stress applied to a piezoelectric element due to vibration of a resonator.SOLUTION: An ultrasonic transducer 1 comprises a base part 14, a piezoelectric element 11, a diaphragm 10, and a resonator 12. The resonator 12 is bonded to a first surface 21 of the diaphragm 10. A surface, of the piezoelectric element 11, opposite to the side bonded to the base part 14 is bonded to a second surface 22 of the diaphragm 10. The piezoelectric element 11 has a through-hole 30 penetrating in the thickness direction of the diaphragm 10. In the plane direction perpendicular to the thickness direction of the diaphragm 10, a boding part 40 between the diaphragm 10 and the resonator 12 is located inner side than a node 20 of vibration of the diaphragm 10, and the through-hole 30 is located inner side than the node 20.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to ultrasound transducers. [Background technology]

[0002] Patent Document 1 discloses an ultrasonic transducer. This ultrasonic transducer includes a piezoelectric vibrating body made of a piezoelectric body and a metal body bonded together with an adhesive, and a funnel-shaped resonator fixed to the piezoelectric vibrating body. The piezoelectric vibrating body is fixed on a base member via a buffer material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-258098 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of ultrasonic transducer, when the ultrasonic transducer is driven, the resonator vibrates, and stress is easily applied to the piezoelectric body (piezoelectric element) near the joint between the resonator and the metal (diaphragm). For this reason, there is concern that repeated driving of the ultrasonic transducer may cause cracks or damage to the piezoelectric body (piezoelectric element).

[0005] An object of the present disclosure is to provide a technique that can reduce stress applied to a piezoelectric element due to vibration of a resonator. [Means for solving the problem]

[0006] [1] A first ultrasonic transducer of the present invention comprises a base portion, a piezoelectric element bonded to the base portion, a vibration plate bonded to the piezoelectric element and vibrating to generate an annular node, and a resonator bonded to the vibration plate. The resonator is bonded to a first surface on one side in the thickness direction of the vibration plate. A surface of the piezoelectric element opposite to the side bonded to the base portion is bonded to a second surface on the other side in the thickness direction of the vibration plate. The piezoelectric element has a through hole formed therethrough in the thickness direction. In a planar direction perpendicular to the thickness direction, the bonded portion between the vibration plate and the resonator is located inside the node, and the through hole is also located inside the node.

[0007] In this ultrasonic transducer, the joint between the diaphragm and the resonator is located inside the vibration node of the diaphragm. Therefore, stress is easily applied to the piezoelectric element inside the node. However, the through-hole of the piezoelectric element is located in an area where stress from this joint is easily applied. Therefore, with this ultrasonic transducer, the stress applied to the piezoelectric element due to the vibration of the resonator can be reduced.

[0008] [2] A second ultrasonic transducer of the present invention includes a base portion, a piezoelectric element bonded to the base portion, a vibration plate bonded to the piezoelectric element and vibrating to generate annular nodes, and a resonator bonded to the vibration plate. The resonator is bonded to a first surface on one side in the thickness direction of the vibration plate. A surface of the piezoelectric element opposite to the side bonded to the base portion is bonded to a second surface on the other side in the thickness direction of the vibration plate. A through hole is formed in the piezoelectric element, penetrating through in the thickness direction. In a planar direction perpendicular to the thickness direction, the bonded portion between the vibration plate and the resonator is located inside an inscribed circle inscribed in the intervening member, and the through hole is located inside the inscribed circle.

[0009] In this ultrasonic transducer, the joint between the diaphragm and the resonator is located inside the inscribed circle inscribed in the interposing member. Therefore, the diaphragm is more likely to vibrate inside the inscribed circle inscribed in the interposing member, and stress is more likely to be applied to the piezoelectric element inside the inscribed circle. However, the through-hole of the piezoelectric element is located in an area where stress from this joint is more likely to be applied. Therefore, with this ultrasonic transducer, the stress applied to the piezoelectric element due to vibration of the resonator can be reduced.

[0010] [3] When viewed from the thickness direction, at least a part of the joint may be disposed in a position overlapping with the through hole.

[0011] According to this configuration, since at least a part of the joint is disposed at a position overlapping with the through hole, the stress applied to the piezoelectric element due to the vibration of the resonator can be reduced more effectively.

[0012] [4] When viewed from the thickness direction, the joint may be disposed at a position where the entire joint overlaps with the through hole.

[0013] According to this configuration, the joint is disposed in a position where the entire joint overlaps the through hole, so that the stress applied to the piezoelectric element due to the vibration of the resonator can be reduced more effectively.

[0014] [5] The diaphragm may have a hole, and may be arranged such that at least a portion of the joint overlaps with the hole when viewed in the thickness direction.

[0015] According to this configuration, the diaphragm can be easily vibrated, and the power consumption for vibrating the diaphragm can be reduced. [Effects of the Invention]

[0016] According to the present invention, it is possible to reduce the stress applied to the piezoelectric element due to the vibration of the resonator. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an ultrasonic transducer according to a first embodiment. [Figure 2] FIG. 2 is a plan view of the piezoelectric element of the first embodiment. [Figure 3] FIG. 3 is a plan view of the ultrasonic transducer of the first embodiment. [Figure 4] FIG. 4 is a plan view of the piezoelectric element according to the second embodiment. [Figure 5] FIG. 5 is a plan view of the ultrasonic transducer of the second embodiment. [Figure 6] FIG. 6 is a plan view of the piezoelectric element according to the third embodiment. [Figure 7] FIG. 7 is a plan view of the ultrasonic transducer of the third embodiment. [Figure 8] FIG. 8 is a cross-sectional view of a diaphragm, a piezoelectric element, and a resonator according to the fourth embodiment. [Figure 9] FIG. 9 is a cross-sectional view of a diaphragm, a piezoelectric element, and a resonator according to the fifth embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a diaphragm, a piezoelectric element, and a resonator according to the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] 1. First embodiment The ultrasonic transducer 1 shown in Figure 1 is used in, for example, medical or industrial ultrasonic devices. The ultrasonic transducer 1 generates ultrasonic waves when a drive signal is applied, and converts the received ultrasonic waves into electrical signals.

[0019] The ultrasonic transducer 1 includes a diaphragm 10 , a piezoelectric element 11 , a resonator 12 , an interposing member 13 , a base portion 14 , a first wiring portion 15 , a second wiring portion 16 , and a case 17 .

[0020] The diaphragm 10 is plate-shaped (more specifically, disk-shaped). The diaphragm 10 is electrically conductive. The diaphragm 10 is made of metal, such as 42 alloy (42Ni-Fe). The width (maximum width) of the diaphragm 10 is greater than the widths (maximum widths) of the resonator 12, the intervening member 13, and the piezoelectric element 11. The width (maximum width) of the diaphragm 10 refers to the length (maximum length) in a direction perpendicular to the thickness direction of the diaphragm 10. In this embodiment, the width (maximum width) of the diaphragm 10 is the diameter of the outer periphery of the diaphragm 10.

[0021] The diaphragm 10 vibrates to generate an annular (more specifically, circular) node 20. The diaphragm 10 generates only one annular node 20. The node 20 is the portion where the amount of displacement in the thickness direction of the diaphragm 10 is smallest or where there is no vibration when the diaphragm 10 vibrates. The node 20 is uniquely determined by the shapes and materials of the diaphragm 10, the piezoelectric element 11, and the resonator 12. Note that while the piezoelectric element 11 is exaggerated in FIG. 1, it is actually much smaller than the diaphragm 10 and the resonator 12. Therefore, the position of the node 20 is largely determined by the shapes and materials of the diaphragm 10 and the resonator 12, and the shape and material of the piezoelectric element 11 have little effect on determining the position of the node 20. The outer periphery of the diaphragm 10 is a free end. In other words, the ultrasonic transducer 1 is a so-called open type, which is more susceptible to vibration than a closed type in which the outer periphery of the diaphragm 10 is fixed. In a planar direction perpendicular to the plate thickness direction, the nodes 20 occur inside the outer periphery and outside the center of the diaphragm 10. The vibration of the diaphragm 10 increases from the nodes 20 toward the outer periphery and from the nodes 20 toward the center.

[0022] The diaphragm 10 has a first surface 21 on one side in the thickness direction and a second surface 22 on the other side. A resonator 12 is bonded to the first surface 21. A piezoelectric element 11 is bonded to the second surface 22. In this specification, the term "bonding" is a concept that includes not only a direct bonding configuration but also a bonding configuration via another member.

[0023] Diaphragm 10 has hole 23. Hole 23 is formed in first surface 21 and has a shape in which first surface 21 is recessed. Hole 23 is formed, for example, by cutting. When hole 23 is cut along a plane perpendicular to the thickness direction of diaphragm 10, the cross section is circular and is constant in the thickness direction of diaphragm 10.

[0024] The resonator 12 resonates with the vibration of the diaphragm 10 to generate ultrasonic waves. The resonator 12 functions to increase the efficiency of sound wave transmission from the diaphragm 10, which is excited in response to the periodic supply of power to the piezoelectric element 11. The resonator 12 is made of metal, such as an aluminum alloy. The resonator 12 is bonded to the diaphragm 10. The bonding method is not limited, and may be, for example, bonding with an adhesive such as an epoxy adhesive, or may be soldering, ultrasonic welding, laser welding, or the like. The resonator 12 is cone-shaped. The resonator 12 has a flat portion 12A and a tapered portion 12B. The flat portion 12A is flat and plate-shaped (more specifically, disc-shaped). The flat portion 12A is bonded to the first surface 21 of the diaphragm 10. The flat portion 12A has a shape that fits within the hole 23 and is bonded to the bottom surface 23A of the hole 23 formed in the first surface 21. Tapered portion 12B extends cylindrically from the outer circumferential edge of flat portion 12A toward the opposite side from diaphragm 10. The inner circumferential surface of tapered portion 12B tapers toward the opposite side from diaphragm 10.

[0025] The piezoelectric element 11 has a plate shape and is bonded to the diaphragm 10 so as to be laminated. The piezoelectric element 11 is bonded to the diaphragm 10 using a heat-curing epoxy adhesive or the like. As shown in FIG. 2, the piezoelectric element 11 has a rectangular shape when viewed in the thickness direction of the diaphragm 10. A through-hole 30 is formed in the piezoelectric element 11, penetrating the diaphragm 10 in the thickness direction. A cross section of the through-hole 30 cut along a plane perpendicular to the penetration direction is circular. As shown in FIG. 1, the piezoelectric element 11 has a plate-shaped piezoelectric body 31 and electrodes 32 and 33 provided on both sides of the piezoelectric body 31 in the thickness direction. The piezoelectric body 31 is made of a ceramic such as lead zirconate titanate (PZT) or potassium sodium niobate (KNN). One electrode 32 of the electrodes 32 and 33 provided on both sides of the piezoelectric element 11 is bonded to the diaphragm 10 and is electrically connected to the first wiring portion 15 via the diaphragm 10. Of the electrodes 32 provided on both sides of the piezoelectric element 11, the other electrode 33 is electrically connected to the second wiring portion 16. A base portion 14 is joined via an intervening member 13 to the surface of the piezoelectric element 11 opposite to the vibration plate 10 side.

[0026] Intervening member 13 is disposed between piezoelectric element 11 and base portion 14 and is bonded to both piezoelectric element 11 and base portion 14. Intervening member 13 is insulating and elastic. Intervening member 13 has a lower Young's modulus than base portion 14. Intervening member 13 is made of, for example, rubber such as silicone rubber or resin such as a silicon-based adhesive. Intervening member 13 is annular (more specifically, annular). The axial direction of intervening member 13 is aligned with the thickness direction of diaphragm 10, more specifically, the same as the thickness direction of diaphragm 10. Intervening member 13 is disposed such that, in a planar direction perpendicular to the thickness direction of diaphragm 10, vibration node 20 of diaphragm 10 is located between inscribed circle 13A inscribed in intervening member 13 and circumscribed circle 13B circumscribed in intervening member 13 (see FIG. 3).

[0027] The base 14 is made of synthetic resin and is configured as a resin base. The base 14 is plate-shaped. The thickness direction of the base 14 is the same as the thickness direction of the diaphragm 10, more specifically, the same as the thickness direction of the diaphragm 10.

[0028] The first wiring portion 15 has a first terminal 15A and a first coil spring 15B made of metal. A first base through-hole 14A is formed in the base portion 14, penetrating the base portion 14 in the thickness direction. The first wiring portion 15 is inserted through the first base through-hole 14A. The first terminal 15A is fixed to the base portion 14 at a position that closes the opening of the first base through-hole 14A on the side opposite to the diaphragm 10 side. The direction of expansion and contraction of the first coil spring 15B is along the thickness direction of the diaphragm 10, and more specifically, is the same as the thickness direction. The first coil spring 15B is sandwiched between the diaphragm 10 and the first terminal 15A, and is positioned in a compressed state by being pressed by the diaphragm 10 and the first terminal 15A. One end of the first coil spring 15B contacts the diaphragm 10, and the other end contacts the first terminal 15A. The first wiring portion 15 is electrically connected to one of the positive electrode side conductive path and the negative electrode side conductive path (for example, ground).

[0029] The second wiring portion 16 has a second terminal 16A and a second coil spring 16B made of metal. A second base through-hole 14B is formed in the base portion 14, penetrating the base portion 14 in the thickness direction. The second wiring portion 16 is inserted through the second base through-hole 14B. The second terminal 16A is fixed to the base portion 14 at a position that closes the opening of the second base through-hole 14B on the side opposite to the diaphragm 10 side. The direction of expansion and contraction of the second coil spring 16B is along the thickness direction of the diaphragm 10, and more specifically, is the same as the thickness direction. The second coil spring 16B is sandwiched and disposed between the piezoelectric element 11 and the second terminal 16A, and is disposed in a compressed state by being pressed by the piezoelectric element 11 and the second terminal 16A. One end of the second coil spring 16B contacts the surface of the piezoelectric element 11 opposite to the diaphragm 10 side (i.e., the electrode 33 of the piezoelectric element 11), and the other end contacts the second terminal 16A. The second wiring portion 16 is electrically connected to the other of the positive electrode side conductive path and the negative electrode side conductive path (for example, ground).

[0030] The case 17 is a member that protects the resonator 12 to prevent foreign matter from coming into contact with the resonator 12. The case 17 is fixed to the base portion 14. The case 17 has a peripheral wall portion 17A that surrounds the periphery of the resonator 12. A plurality of openings are formed in the case 17 on the side opposite the base portion 14 side of the resonator 12, and ultrasonic waves are sent to the outside through these openings and enter the case 17 from the outside.

[0031] 3, in a planar direction perpendicular to the thickness direction of the diaphragm 10, the joint 40 between the diaphragm 10 and the resonator 12 is located inside the node 20, and the through-hole 30 of the piezoelectric element 11 is located inside the node 20. Furthermore, in the planar direction, the joint 40 between the diaphragm 10 and the resonator 12 is located inside the inscribed circle 13A inscribed in the interposition member 13, and the through-hole 30 is located inside the inscribed circle 13A. Furthermore, when viewed from the thickness direction of the diaphragm 10, the joint 40 is located in a position where it entirely overlaps with the through-hole 30. Furthermore, when viewed from the thickness direction of the diaphragm 10, the joint 40 is located in a position where it entirely overlaps with the hole 23.

[0032] The following description relates to the effects of the first embodiment. In the ultrasonic transducer 1 of the first embodiment, the joint 40 between the diaphragm 10 and the resonator 12 is located inside the vibration node 20 of the diaphragm 10. Therefore, stress is likely to be applied to the piezoelectric element 11 inside the node 20. However, the through hole 30 of the piezoelectric element 11 is located in an area where stress from the joint 40 is likely to be applied. Therefore, with this ultrasonic transducer 1, the stress applied to the piezoelectric element 11 due to the vibration of the resonator 12 can be reduced.

[0033] Furthermore, in the ultrasonic transducer 1 of the first embodiment, the joint 40 between the diaphragm 10 and the resonator 12 is located inside the inscribed circle 13A inscribed in the intervening member 13. Therefore, the diaphragm 10 is more likely to vibrate inside the inscribed circle 13A inscribed in the intervening member 13, and stress is more likely to be applied to the piezoelectric element 11 inside the inscribed circle 13A. However, the through-hole 30 of the piezoelectric element 11 is located in an area where stress from the joint 40 is more likely to be applied. Therefore, with this ultrasonic transducer 1, the stress applied to the piezoelectric element 11 due to vibration of the resonator 12 can be reduced.

[0034] Furthermore, when viewed from the thickness direction of the diaphragm 10, the joint 40 is disposed at a position where it entirely overlaps with the through-hole 30. Therefore, since the joint 40 is disposed at a position where it entirely overlaps with the through-hole 30, the stress applied to the piezoelectric element 11 due to the vibration of the resonator 12 can be more effectively reduced.

[0035] Furthermore, when viewed in the thickness direction of diaphragm 10, joint 40 is positioned so that the entirety of joint 40 overlaps hole 23. This makes it easier for diaphragm 10 to vibrate, and can reduce the power consumption required to vibrate diaphragm 10.

[0036] Second Embodiment In the first embodiment, the joints are positioned so that they entirely overlap the through holes when viewed in the thickness direction of the diaphragm, but they do not have to be positioned so that they entirely overlap the through holes. In the second embodiment, an example will be described in which the joints are positioned so that they partially overlap the through holes when viewed in the thickness direction of the diaphragm. The ultrasonic transducer of the second embodiment differs from the ultrasonic transducer of the first embodiment only in the shape of the piezoelectric element, but is otherwise common. In the following description, the same symbols are used for components common to the first embodiment, and detailed description will be omitted.

[0037] 4, the piezoelectric element 211 of the second embodiment has a rectangular shape when viewed in the thickness direction of the vibration plate 10. A through hole 230 is formed in the piezoelectric element 211, penetrating in the thickness direction of the vibration plate 10. The shape of a cross section obtained by cutting the through hole 230 along a plane perpendicular to the penetrating direction of the through hole 230 is rectangular.

[0038] 5, when viewed from the thickness direction of the diaphragm 10, a part of the joint 40 between the diaphragm 10 and the resonator 12 is disposed at a position overlapping with the through-hole 230. Furthermore, when viewed from the thickness direction of the diaphragm 10, the through-hole 230 has a part that does not overlap with the joint 40.

[0039] As described above, when viewed in the thickness direction, the ultrasonic transducer 201 of the second embodiment is disposed in a position where a part of the joint 40 overlaps with the through-hole 230. Therefore, the ultrasonic transducer 201 can more effectively reduce the stress applied to the piezoelectric element 211 due to the vibration of the resonator 12, compared to a configuration in which the joint 40 is disposed in a position where it does not overlap with the through-hole 230 at all.

[0040] Third Embodiment In the first embodiment, the number of through holes formed in the piezoelectric element is one, but there may be more than one. In the third embodiment, an example in which multiple through holes are formed in the piezoelectric element will be described. The ultrasonic transducer of the third embodiment differs from the ultrasonic transducer of the first embodiment only in the shape of the piezoelectric element, and is otherwise common to both. In the following description, the same reference numerals will be used to designate components common to the first embodiment, and detailed description will be omitted.

[0041] As shown in Fig. 6, the piezoelectric element 311 of the third embodiment has a rectangular shape when viewed in the thickness direction of the vibration plate 10. A through hole 330 is formed in the piezoelectric element 311, penetrating the vibration plate 10 in the thickness direction. A cross section of the through hole 330 cut along a plane perpendicular to the penetrating direction of the through hole 330 has a circular shape. A plurality of through holes 330 (five in this embodiment) are formed in the piezoelectric element 311. More specifically, one through hole 330A is formed in the center of the piezoelectric element 311, and four through holes 330B are formed around the through hole 330A.

[0042] As shown in FIG. 7, when viewed in the thickness direction of the diaphragm 10, a part of the joint 40 between the diaphragm 10 and the resonator 12 is disposed at a position overlapping the through-hole 330.

[0043] As described above, when viewed in the thickness direction, the ultrasonic transducer 301 of the third embodiment is disposed in a position where a part of the joint 40 overlaps with the through-hole 330. Therefore, the ultrasonic transducer 301 can more effectively reduce the stress applied to the piezoelectric element 311 due to the vibration of the resonator 12, compared to a configuration in which the joint 40 is disposed in a position where it does not overlap with the through-hole 330 at all.

[0044] <Fourth embodiment> In the first embodiment, the diaphragm has a hole, but the diaphragm may have no hole. The ultrasonic transducer of the fourth embodiment differs from the ultrasonic transducer of the first embodiment in that the diaphragm does not have a hole, but shares other features. In the following description, the same reference numerals are used to designate components common to the first embodiment, and detailed description thereof will be omitted.

[0045] As shown in Fig. 8, the ultrasonic transducer of the fourth embodiment includes a diaphragm 410, a piezoelectric element 11, and a resonator 12. The diaphragm 410 has the same configuration as the diaphragm 10 of the first embodiment, except that it does not have any holes. In other words, both surfaces of the diaphragm 410 in the thickness direction are flat. The thickness of the diaphragm 410 is uniform across the entire diaphragm 410. According to the ultrasonic transducer of the fourth embodiment, the diaphragm 410 does not have any holes, so that the diaphragm 410 can be easily formed.

[0046] Fifth Embodiment In the first embodiment, the holes in the diaphragm are formed by cutting, but the holes in the diaphragm may be formed by another method. In the fifth embodiment, an example will be described in which the holes in the diaphragm are formed by half-punching. The ultrasonic transducer of the fifth embodiment differs from the ultrasonic transducer of the first embodiment in that the holes in the diaphragm are formed by half-punching, but is common in other respects. In the following description, the same symbols are used for components common to the first embodiment, and detailed description will be omitted.

[0047] 9, the ultrasonic transducer of the fifth embodiment includes a diaphragm 510, a piezoelectric element 11, and a resonator 12. The diaphragm 510 has a first surface 521 on one side in the thickness direction and a second surface 522 on the other side. The resonator 12 is bonded to the first surface 521. The piezoelectric element 11 is bonded to the second surface 522.

[0048] Diaphragm 510 has hole 523 and protrusion 524. Hole 523 is formed in first surface 521 and has a shape in which first surface 521 is recessed. Hole 523 is formed by half-punching. A cross section of hole 523 cut along a plane perpendicular to the thickness direction of diaphragm 510 is circular and is constant in the thickness direction of diaphragm 510. Flat portion 12A of resonator 12 fits into hole 523 and is joined to a bottom surface 523A of hole 523.

[0049] The convex portion 524 is formed on the second surface 522. When viewed from the thickness direction of the vibration plate 510, at least a portion of the convex portion 524 is arranged at a position overlapping the hole portion 523. The convex portion 524 is formed when the hole portion 523 is formed by half-punching. The convex portion 524 fits into the through hole 30 of the piezoelectric element 11. The protruding dimension of the convex portion 524 is smaller than the thickness of the piezoelectric element 11. Therefore, the convex portion 524 does not protrude outside the through hole 30.

[0050] According to the ultrasonic transducer of the fifth embodiment, chips are less likely to be generated compared to when holes in the vibration plate are formed by cutting.

[0051] Sixth Embodiment In the first embodiment, the holes in the diaphragm do not penetrate the diaphragm, but the holes may penetrate the diaphragm. In the sixth embodiment, an example in which the holes in the diaphragm penetrate the diaphragm will be described. The ultrasonic transducer of the sixth embodiment differs from the ultrasonic transducer of the first embodiment in that the holes in the diaphragm penetrate the diaphragm, but is common in other respects. In the following description, the same symbols are used for components common to the first embodiment, and detailed description will be omitted.

[0052] 10, the ultrasonic transducer of the sixth embodiment includes a diaphragm 610, a piezoelectric element 11, and a resonator 12. The diaphragm 610 has a first surface 621 on one side in the thickness direction and a second surface 622 on the other side. The resonator 12 is bonded to the first surface 621. The piezoelectric element 11 is bonded to the second surface 622.

[0053] Diaphragm 610 has hole 623. Hole 623 penetrates diaphragm 610 in the thickness direction. Hole 623 is arranged to be located inside the outer periphery of flat portion 12A of resonator 12 in a planar direction perpendicular to the thickness direction of diaphragm 610. Hole 623 is arranged to be located inside the inner wall of through-hole 30 in a planar direction perpendicular to the thickness direction of diaphragm 610. A cross section of hole 623 cut along a plane perpendicular to the thickness direction of diaphragm 610 is circular, and the cross section is constant in the thickness direction of diaphragm 610.

[0054] <Other embodiments> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments are also included within the technical scope of the present invention. Furthermore, the various features of the above-mentioned embodiments and the embodiments to be described later may be combined in any combination as long as they are not contradictory.

[0055] In each of the above embodiments, when viewed from the thickness direction of the vibration plate, the joint is positioned so that at least a portion of it overlaps with the through hole, but the joint may also be positioned so that it does not overlap with the through hole at all.

[0056] In each of the above embodiments, the first coil spring and the second coil spring are not joined together, but they may be joined together. The joining method is not limited to this, and may be, for example, soldering, laser welding, ultrasonic welding, or the like.

[0057] It should be noted that the embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the embodiments disclosed herein, but is intended to include all modifications within the scope indicated by the claims or the scope equivalent to the claims. [Explanation of symbols]

[0058] 1...Ultrasonic transducer 10…Diaphragm 11...Piezoelectric element 12...Resonator 12A…Flat area 12B...Tapered section 13…Intervening member 13A...Inscribed circle 13B…Circumcircle 14...Base 14A...First base through hole 14B...Second base through hole 15...1st wiring section 15A…1st terminal 15B...First coil spring 16…Second wiring section 16A...Second terminal 16B...Second coil spring 17…Case 17A…Peripheral wall part Section 20... 21...Side 1 22…Second side 23...Hole 23A…Bottom surface 30...Through hole 31...Piezoelectric body 32...Electrode 33...Electrode 40…Joint part 201...Ultrasonic transducer 211...Piezoelectric element 230...Through hole 301...Ultrasonic transducer 311...Piezoelectric element 330...Through hole 330A…Through hole 330B…Through hole 410…Diaphragm 510...Diaphragm 521...Side 1 522…Second side 523...Hole 610…Diaphragm 621...Side 1 622…Second side 623...Hole

Claims

1. A base portion; a piezoelectric element bonded to the base portion; a vibration plate joined to the piezoelectric element and vibrating to generate an annular node; a resonator joined to the diaphragm; Equipped with the diaphragm has a hole portion formed in a concave shape so as to reduce the thickness of the diaphragm on a first surface on one side in a thickness direction of the diaphragm, the resonator is connected to the diaphragm so as to be disposed at a position where at least a portion of the resonator is in contact with the hole in the first surface; Furthermore, the resonator has a plate-like flat portion and a tapered portion extending in a cylindrical shape from an outer peripheral edge of the flat portion toward an opposite side to the diaphragm side, the flat portion being disposed at a position separated from an inner peripheral surface of the hole portion and being joined to a bottom surface of the hole portion, a surface of the piezoelectric element opposite to the surface bonded to the base portion is bonded to a second surface of the vibration plate on the other side in the thickness direction; a through hole penetrating the piezoelectric element in the thickness direction; In a planar direction perpendicular to the thickness direction, a joint between the diaphragm and the resonator is disposed inside the node, and the through hole is disposed inside the node. Ultrasonic transducer.

2. A base portion; an annular interposition member joined to the base portion; a piezoelectric element joined to the base portion via the intervening member; a vibration plate joined to the piezoelectric element and vibrating to generate an annular node; a resonator joined to the diaphragm; Equipped with the intermediate member has a lower Young's modulus than the base portion, a first surface of the diaphragm on one side in a thickness direction thereof is joined to the resonator; the diaphragm has a hole formed in a concave shape on the first surface so as to reduce the thickness thereof; the resonator has a plate-like flat portion and a tapered portion extending in a cylindrical shape from an outer peripheral edge of the flat portion toward an opposite side to the diaphragm side, the flat portion being disposed at a position spaced apart from an inner peripheral surface of the hole portion and being joined to a bottom surface of the hole portion; a second surface of the vibration plate on the other side in the thickness direction is bonded to a surface of the piezoelectric element opposite to a surface bonded to the base portion, a through hole penetrating the piezoelectric element in the thickness direction; In a planar direction perpendicular to the thickness direction, a joint between the diaphragm and the resonator is located inside an inscribed circle inscribed in the interposition member, and the through hole is located inside the inscribed circle. Ultrasonic transducer.

3. When viewed from the thickness direction, at least a part of the joint is disposed at a position overlapping with the through hole.

3. The ultrasonic transducer according to claim 1 or 2.

4. When viewed from the thickness direction, the joint portion is disposed at a position where the entire joint portion overlaps the through hole.

4. The ultrasonic transducer according to claim 3.

5. When viewed from the thickness direction, at least a part of the joint is disposed at a position overlapping with the hole.

5. The ultrasonic transducer according to claim 1.

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