Ultrasonic transducer

Abstract

To provide a technique capable of suppressing noise caused by vibration of a coil spring in an ultrasonic transducer.SOLUTION: An ultrasonic transducer 1 includes a first compression coil spring 40 and a second compression coil spring 50. At least a portion of the first compression coil spring 40 is arranged in a first through hole 15. At least a portion of the second compression coil spring 50 is arranged in a second through hole 16. An inner peripheral surface of the first through hole 15 has a first guide part 15A where a gap between the outer peripheral edge of the first compression coil spring 40 and the inner peripheral surface is narrowest in a thickness direction, and a first separation part 15B where a gap between the outer peripheral edge of the first compression coil spring 40 and the inner peripheral surface is greater than the gap in the first guide part 15A. An inner peripheral surface of the second through hole 16 has a second guide part 16A where a gap between the outer peripheral edge of the second compression coil spring 50 and the inner peripheral surface is narrowest in a thickness direction, and a second separation part 16B where a gap between the outer peripheral edge of the second compression coil spring 50 and the inner peripheral surface is greater than the gap in the second guide part 16A.SELECTED DRAWING: Figure 1

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 diaphragm, a piezoelectric element bonded to the diaphragm, a first wiring portion, a second wiring portion, and a base portion. The first wiring portion has a first contact portion that is in contact with or bonded to a first surface of the diaphragm. The second wiring portion has a second contact portion that is in contact with or bonded to a second surface of the piezoelectric element opposite the diaphragm side. A first base through hole and a second base through hole are formed in the base portion. The first wiring portion has a first coil spring that is inserted into the first base through hole. The second wiring portion has a second coil spring that is inserted into the second base through hole. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-28693 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration of Patent Document 1, when the diaphragm vibrates with the first coil spring in contact with the inner circumferential surface of the first base through-hole, the vibration is transmitted to the first coil spring, which may rub against the inner circumferential surface of the first base through-hole, generating noise. Similar problems are of concern for the second coil spring.

[0005] The present disclosure aims to provide a technique capable of suppressing noise caused by vibration of a coil spring in an ultrasonic transducer. [Means for solving the problem]

[0006] The ultrasonic transducer of the present disclosure comprises: a conductive diaphragm that vibrates to generate annular nodes; a piezoelectric element bonded to a part of a first surface on one side of the vibration plate in a thickness direction; a first compression coil spring having a first contact portion that contacts the first surface of the diaphragm; a second compression coil spring having a second contact portion that contacts a second surface of the piezoelectric element opposite to the vibration plate side; a circuit board having a first conductive path that is in contact with a third contact portion of the first compression coil spring opposite to the first contact portion, and a second conductive path that is in contact with a fourth contact portion of the second compression coil spring opposite to the second contact portion; a base portion having a first through hole penetrating in the thickness direction and a second through hole penetrating in the thickness direction, the base portion being disposed between the piezoelectric element and the circuit board; Equipped with At least a portion of the first compression coil spring is disposed within the first through hole, At least a portion of the second compression coil spring is disposed within the second through hole, the first contact portion contacts the first surface of the diaphragm at a position overlapping the node when viewed from the thickness direction; the second contact portion is an ultrasonic transducer that contacts the second surface of the piezoelectric element at a position that overlaps the node when viewed from the thickness direction, an inner peripheral surface of the first through hole has a first guide portion where a gap between the inner peripheral surface and an outer peripheral edge of the first compression coil spring is narrowest in the thickness direction, and a first separation portion where a gap between the inner peripheral surface and the outer peripheral edge of the first compression coil spring is larger than that between the inner peripheral surface and the first guide portion; The inner surface of the second through hole has a second guide portion where the gap between the second through hole and the outer edge of the second compression coil spring is narrowest in the thickness direction, and a second separation portion where the gap between the second through hole and the outer edge of the second compression coil spring is larger than that of the second guide portion. [Effects of the Invention]

[0007] According to the present disclosure, noise caused by vibration of a coil spring in an ultrasonic transducer can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of an ultrasonic transducer according to a first embodiment. [Figure 2] FIG. 2 is a plan view of the base portion, the first wiring portion, and the second wiring portion. [Figure 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 4 is a cross-sectional view of the ultrasonic transducer of the second embodiment. [Figure 5] FIG. 5 is a cross-sectional view of the ultrasonic transducer of the third embodiment. [Figure 6] FIG. 6 is a cross-sectional view of an ultrasonic transducer according to the fourth embodiment. [Figure 7] FIG. 7 is a cross-sectional view of an ultrasonic transducer according to the fifth embodiment. [Figure 8] FIG. 8 is a cross-sectional view of an ultrasonic transducer according to the sixth embodiment. [Figure 9] FIG. 9 is a cross-sectional view of an ultrasonic transducer according to the seventh embodiment. [Figure 10] FIG. 10 is a cross-sectional view of an ultrasonic transducer according to the eighth embodiment. [Figure 11] FIG. 11 is a cross-sectional view of an ultrasonic transducer according to the ninth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Description of the embodiments of the present disclosure] In the following, embodiments of the present disclosure are listed and illustrated.

[0010] [1] A conductive diaphragm that vibrates to generate an annular node; a piezoelectric element bonded to a part of a first surface on one side of the vibration plate in a thickness direction; a first compression coil spring having a first contact portion that contacts the first surface of the diaphragm; a second compression coil spring having a second contact portion that contacts a second surface of the piezoelectric element opposite to the vibration plate side; a circuit board having a first conductive path that is in contact with a third contact portion of the first compression coil spring opposite to the first contact portion, and a second conductive path that is in contact with a fourth contact portion of the second compression coil spring opposite to the second contact portion; a base portion having a first through hole penetrating in the thickness direction and a second through hole penetrating in the thickness direction, the base portion being disposed between the piezoelectric element and the circuit board; Equipped with At least a portion of the first compression coil spring is disposed within the first through hole, At least a portion of the second compression coil spring is disposed within the second through hole, the first contact portion contacts the first surface of the diaphragm at a position overlapping the node when viewed from the thickness direction; the second contact portion is an ultrasonic transducer that contacts the second surface of the piezoelectric element at a position that overlaps the node when viewed from the thickness direction, an inner peripheral surface of the first through hole has a first guide portion where a gap between the inner peripheral surface and an outer peripheral edge of the first compression coil spring is narrowest in the thickness direction, and a first separation portion where a gap between the inner peripheral surface and the outer peripheral edge of the first compression coil spring is larger than that between the inner peripheral surface and the first guide portion; The inner peripheral surface of the second through hole has a second guide portion where the gap between the second through hole and the outer peripheral edge of the second compression coil spring is narrowest in the thickness direction, and a second separation portion where the gap between the second through hole and the outer peripheral edge of the second compression coil spring is larger than that between the second guide portion and the outer peripheral edge of the second compression coil spring. Ultrasonic transducer.

[0011] With this configuration, the first compression coil spring is likely to come into contact with the first guide portion of the inner circumferential surface of the first through hole, but is unlikely to come into contact with the first separation portion. Therefore, even if the first compression coil spring comes into contact with the inner circumferential surface of the first through hole, the contact area is likely to be limited to only a portion of the first through hole in the penetration direction. Therefore, the ultrasonic transducer can suppress noise caused by vibration of the first compression coil spring. Similarly, the ultrasonic transducer can suppress noise caused by vibration of the second compression coil spring.

[0012] [2] At a position in the thickness direction where the first guide portion is disposed, a diameter of an inscribed circle inscribed on an inner peripheral surface of the first through hole is 1.1 times or less the diameter of a circumscribed circle circumscribed on an outer peripheral edge of the first compression coil spring, At a position in the thickness direction where the second guide portion is disposed, a diameter of an inscribed circle inscribed on an inner circumferential surface of the second through hole is 1.1 times or less the diameter of a circumscribed circle circumscribed on an outer circumferential edge of the second compression coil spring. The ultrasonic transducer described in [1].

[0013] This configuration narrows the gap between the first compression coil spring and the first guide portion of the first through hole, making it easier to accurately position the first compression coil spring through the first through hole, and similarly, it makes it easier to accurately position the second compression coil spring through the second through hole.

[0014] [3] The first guide portion is provided at one end of the first through hole in the thickness direction, the third contact portion of the first compression coil spring is disposed at the same position as the first guide portion in the thickness direction; the second guide portion is provided at one end of the second through hole in the thickness direction, The fourth contact portion of the second compression coil spring is disposed at the same position as the second guide portion in the thickness direction. The ultrasonic transducer according to [1] or [2].

[0015] The third contact portion of the first compression coil spring is disposed at the same position as the first guide portion in the thickness direction of the diaphragm. Because the third contact portion is provided at the end of the first compression coil spring, it does not vibrate even when the first compression coil spring vibrates. Therefore, even if the first compression coil spring vibrates while the third contact portion is in contact with the first guide portion, noise is unlikely to be generated. Similarly, even if the second compression coil spring vibrates while the fourth contact portion is in contact with the second guide portion, noise is unlikely to be generated.

[0016] [4] The outer shape of the first compression coil spring is formed to become smaller toward the other side in the thickness direction, The outer shape of the second compression coil spring is formed to become smaller toward the other side in the thickness direction. The ultrasonic transducer according to [3].

[0017] This configuration more reliably prevents the first compression coil spring from contacting the inner circumferential surface of the first through hole at any point other than the first guide portion provided at one end in the thickness direction. Furthermore, this configuration reduces the contact area between the first contact portion of the first compression coil spring and the diaphragm. This reduces the transmission of vibrations from the diaphragm to the first compression coil spring. Moreover, because the first compression coil spring becomes larger toward one end in the thickness direction, it is less likely to collapse or buckle. This makes it easier to prevent the first compression coil spring from contacting the inner circumferential surface of the first through hole due to collapse or buckling. Similarly, this configuration more reliably prevents the second compression coil spring from contacting the inner circumferential surface of the second through hole at any point other than the second guide portion provided at one end in the thickness direction. Furthermore, this configuration reduces the contact area between the second contact portion of the second compression coil spring and the piezoelectric element. This reduces the transmission of vibrations from the diaphragm to the second compression coil spring. Furthermore, because the second compression coil spring becomes larger toward one end in the thickness direction, it is less likely to collapse or buckle. This makes it easier to prevent the second compression coil spring from contacting the inner circumferential surface of the second through hole due to collapse or buckling.

[0018] [5] The inner circumferential surface of the first through hole is formed so that an inscribed circle inscribed in the inner circumferential surface becomes larger toward the other side in the thickness direction, The inner circumferential surface of the second through hole is formed so that an inscribed circle inscribed in the inner circumferential surface becomes larger toward the other side in the thickness direction. The ultrasonic transducer according to [3] or [4].

[0019] This configuration more reliably prevents the first compression coil spring from contacting the inner circumferential surface of the first through hole on the other side in the thickness direction of the diaphragm, and also more reliably prevents the second compression coil spring from contacting the inner circumferential surface of the second through hole on the other side in the thickness direction of the diaphragm.

[0020] [6] The first guide portion is provided at the other end of the first through hole in the thickness direction, The second guide portion is provided at the other end of the second through hole in the thickness direction. The ultrasonic transducer according to [1] or [2].

[0021] This configuration allows the first compression coil spring to be positioned in the first through-hole at a position closest to the diaphragm, and similarly, this configuration allows the second compression coil spring to be positioned in the second through-hole at a position closest to the piezoelectric element.

[0022] [Details of the embodiments of the present disclosure] The ultrasonic transducer of the present disclosure is used in, for example, an ultrasonic distance sensor, an ultrasonic oscillation device, a parametric speaker, and the like.

[0023] 1. First embodiment The ultrasonic transducer 1 of the first embodiment shown in FIG. 1 generates ultrasonic waves when a drive signal is given, and converts the ultrasonic waves into electrical signals when the ultrasonic waves are received.

[0024] The ultrasonic transducer 1 includes a diaphragm 10, a piezoelectric element 11, a resonator 12, an interposed member 13, a base portion 14, a circuit board 30, a first compression coil spring 40, a second compression coil spring 50, and a case 60.

[0025] 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.

[0026] The diaphragm 10 has a piezoelectric element 11 bonded to a first surface 21 on one side in the thickness direction, and a resonator 12 bonded to the other surface. In this specification, the term "bonding" is used to refer not only to a direct bonding configuration, but also to a bonding configuration via another member.

[0027] The resonator 12 resonates with the vibration of the diaphragm 10 to generate ultrasonic waves. The resonator 12 has the function of increasing 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 soldering. The resonator 12 is cone-shaped. The inner peripheral surface of the resonator 12 is tapered, widening as it approaches the opposite side from the diaphragm 10.

[0028] The piezoelectric element 11 has a plate shape. The piezoelectric element 11 is bonded to the diaphragm 10 so as to be stacked. The piezoelectric element 11 is bonded to a part of the first surface 21 of the diaphragm 10. In other words, the first surface 21 of the diaphragm 10 includes a part to which the piezoelectric element 11 is bonded and a part to which it is not bonded. The piezoelectric element 11 is bonded to the diaphragm 10 with a heat-curing epoxy adhesive or the like.

[0029] The piezoelectric element 11 includes a plate-shaped piezoelectric body 11A and electrodes 11B and 11C provided on both sides of the piezoelectric body 11A in the thickness direction. The piezoelectric body 11A is made of a ceramic, such as lead zirconate titanate (PZT) or potassium sodium niobate (KNN). Of the electrodes 11B and 11C provided on both sides of the piezoelectric element 11, one electrode 11B is bonded to the diaphragm 10 and electrically connected to a first compression coil spring 40 via the diaphragm 10. The other electrode 11C of the electrodes 11B and 11C provided on both sides of the piezoelectric element 11 is electrically connected to a second compression coil spring 50. A base portion 14 is bonded to a second surface 22 of the piezoelectric element 11 opposite the diaphragm 10 side via an intervening member 13.

[0030] 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, circular). 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.

[0031] Base portion 14 has insulating properties. Base portion 14 is made of synthetic resin and configured as a resin stand. Base portion 14 has first through-hole 15 penetrating diaphragm 10 in the thickness direction and second through-hole 16 penetrating diaphragm 10 in the thickness direction.

[0032] In this embodiment, the cross-sectional shape of the inner circumferential surface of the first through hole 15 and the second through hole 16 is circular, but it does not have to be circular. For example, the cross-sectional shape may be polygonal or elliptical, or may be a shape in which a portion of the inner circumferential surface in the circumferential direction protrudes inward, or a shape in which a portion of the inner circumferential surface in the circumferential direction is recessed outward. Furthermore, in this embodiment, the cross-sectional shape is constant in the penetration direction of the first through hole 15 and the second through hole 16, but it does not have to be constant. Note that the cross-sectional shape here refers to the cross-sectional shape when cut in a direction perpendicular to the penetration direction of the first through hole 15 and the second through hole 16.

[0033] The circuit board 30 is provided on the opposite side of the base portion 14 to the piezoelectric element 11 side. In other words, the base portion 14 is disposed between the piezoelectric element 11 and the circuit board 30. The circuit board 30 has a board main body 31, a first conductive path 32, and a second conductive path 33.

[0034] The substrate body 31 is insulating. The substrate body 31 is plate-shaped. The first conductive path 32 and the second conductive path 33 are formed by wiring patterns provided on the substrate body 31. At least a portion of the first conductive path 32 is exposed to the vibration plate 10 side. At least a portion of the first conductive path 32 faces the first surface 21 of the vibration plate 10 via the first through hole 15. At least a portion of the second conductive path 33 is exposed to the piezoelectric element 11 side. At least a portion of the second conductive path 33 faces the second surface 22 of the piezoelectric element 11 via the second through hole 16. A drive voltage for driving the ultrasonic transducer 1 is applied between the first conductive path 32 and the second conductive path 33.

[0035] The first compression coil spring 40 is electrically conductive. The first compression coil spring 40 is made of, for example, metal. At least a portion of the first compression coil spring 40 is disposed within the first through-hole 15. The first compression coil spring 40 is disposed between the diaphragm 10 and the first conductive path 32. The first compression coil spring 40 has a first contact portion 41 that contacts the first surface 21 of the diaphragm 10 and a third contact portion 42 that contacts the first conductive path 32. The first contact portion 41 may or may not be fixed to the first surface 21. The third contact portion 42 may or may not be fixed to the first conductive path 32. The first compression coil spring 40 electrically connects the first conductive path 32 to the diaphragm 10.

[0036] The inner surface of the first through hole 15 has a first guide portion 15A where the gap between the first through hole 15 and the outer peripheral edge of the first compression coil spring 40 is narrowest in the thickness direction, and a first separation portion 15B where the gap between the first through hole 15 and the outer peripheral edge of the first compression coil spring 40 is larger than that of the first guide portion 15A.

[0037] Specifically, the inner peripheral surface of the first through hole 15 is cylindrical. In contrast, the first compression coil spring 40 is a conical spring. The first compression coil spring 40 is continuously disposed from one end of the first through hole 15 to the other end in the thickness direction of the diaphragm 10. The first compression coil spring 40 is formed so that a circumscribed circle circumscribing the outer periphery of the first compression coil spring 40 becomes smaller as it approaches the diaphragm 10. In other words, the inner peripheral surface of the first through hole 15, at one end in the thickness direction of the diaphragm 10, is the first guide portion 15A. Furthermore, the portion of the inner peripheral surface of the first through hole 15 on the other side in the thickness direction of the diaphragm 10 relative to the first guide portion 15A is the first separation portion 15B.

[0038] With this configuration, the first compression coil spring 40 is likely to come into contact with the first guide portion 15A on the inner circumferential surface of the first through hole 15, but is unlikely to come into contact with the first separating portion 15B. Therefore, even if the first compression coil spring 40 comes into contact with the inner circumferential surface of the first through hole 15, the contact area is likely to be limited to only a portion of the first through hole 15 in the penetration direction. Therefore, the ultrasonic transducer 1 can suppress noise caused by vibration of the first compression coil spring 40.

[0039] Furthermore, the third contact portion 42 of the first compression coil spring 40 is disposed at the same position as the first guide portion 15A in the thickness direction of the diaphragm 10. That is, the third contact portion 42 of the first compression coil spring 40 is disposed at the same position as the first guide portion 15A in the thickness direction of the diaphragm 10. Because the third contact portion 42 is provided at the end of the first compression coil spring 40, it does not vibrate even when the first compression coil spring 40 vibrates. For this reason, even if the first compression coil spring 40 vibrates with the third contact portion 42 in contact with the first guide portion 15A, noise is unlikely to be generated.

[0040] The outer shape of the first compression coil spring 40 is formed to become smaller toward the other side in the thickness direction of the diaphragm 10. This configuration more reliably prevents the first compression coil spring 40 from contacting the inner circumferential surface of the first through hole 15 at a location other than the first guide portion 15A provided at one end of the diaphragm 10 in the thickness direction. Furthermore, this configuration reduces the contact area between the first contact portion 41 of the first compression coil spring 40 and the diaphragm 10. This makes it difficult for vibrations from the diaphragm 10 to be transmitted to the first compression coil spring 40. Moreover, because the first compression coil spring 40 becomes larger toward one side in the thickness direction, it is less likely to collapse or buckle. This makes it easier to prevent the first compression coil spring 40 from contacting the inner circumferential surface of the first through hole 15 due to collapse or buckling.

[0041] The second compression coil spring 50 is electrically conductive. The second compression coil spring 50 is made of, for example, metal. At least a portion of the second compression coil spring 50 is disposed within the second through-hole 16. The second compression coil spring 50 is disposed between the piezoelectric element 11 and the second conductive path 33. The second compression coil spring 50 has a second contact portion 51 that contacts the second surface 22 of the piezoelectric element 11 and a fourth contact portion 52 that contacts the second conductive path 33. The second contact portion 51 may or may not be fixed to the second surface 22. The fourth contact portion 52 may or may not be fixed to the second conductive path 33. The second compression coil spring 50 electrically connects the second conductive path 33 to the piezoelectric element 11.

[0042] The inner surface of the second through hole 16 has a second guide portion 16A where the gap with the outer edge of the second compression coil spring 50 is narrowest in the thickness direction, and a second separation portion 16B where the gap with the outer edge of the second compression coil spring 50 is larger than that of the second guide portion 16A.

[0043] Specifically, the inner peripheral surface of the second through hole 16 is cylindrical. In contrast, the second compression coil spring 50 is a conical spring. The second compression coil spring 50 is continuously disposed from one end of the second through hole 16 to the other end in the thickness direction of the diaphragm 10. The second compression coil spring 50 is formed so that the circumscribed circle circumscribing the outer periphery of the second compression coil spring 50 becomes smaller as it approaches the piezoelectric element 11. In other words, the inner peripheral surface of the second through hole 16, at one end in the thickness direction of the diaphragm 10, is the second guide portion 16A. Furthermore, the inner peripheral surface of the second through hole 16, at the other side in the thickness direction of the diaphragm 10 relative to the second guide portion 16A, is the second separation portion 16B.

[0044] With this configuration, the second compression coil spring 50 is likely to come into contact with the second guide portion 16A on the inner circumferential surface of the second through hole 16, but is unlikely to come into contact with the second separation portion 16B. Therefore, even if the second compression coil spring 50 comes into contact with the inner circumferential surface of the second through hole 16, the contact area is likely to be limited to only a portion of the second through hole 16 in the penetration direction. Therefore, the ultrasonic transducer 1 can suppress noise caused by vibration of the second compression coil spring 50.

[0045] Furthermore, the fourth contact portion 52 of the second compression coil spring 50 is disposed at the same position as the second guide portion 16A in the thickness direction of the diaphragm 10. That is, the fourth contact portion 52 of the second compression coil spring 50 is disposed at the same position as the second guide portion 16A in the thickness direction of the diaphragm 10. Because the fourth contact portion 52 is provided at the end of the second compression coil spring 50, it does not vibrate even when the second compression coil spring 50 vibrates. For this reason, even if the second compression coil spring 50 vibrates with the fourth contact portion 52 in contact with the second guide portion 16A, noise is unlikely to be generated.

[0046] The outer shape of the second compression coil spring 50 is formed to become smaller toward the other side in the thickness direction of the diaphragm 10. This configuration more reliably prevents the second compression coil spring 50 from contacting the inner circumferential surface of the second through hole 16 at a location other than the second guide portion 16A provided at one end of the diaphragm 10 in the thickness direction. Furthermore, this configuration reduces the contact area between the second contact portion 51 of the second compression coil spring 50 and the diaphragm 10. This reduces the transmission of vibrations from the diaphragm 10 to the second compression coil spring 50. Moreover, because the second compression coil spring 50 becomes larger toward one side in the thickness direction, it is less likely to collapse or buckle. This makes it easier to prevent the second compression coil spring 50 from contacting the inner circumferential surface of the second through hole 16 due to collapse or buckling.

[0047] The case 60 is a member that protects the resonator 12 to prevent foreign matter from coming into contact with the resonator 12. The case 60 is fixed to the base 14. The case 60 has a peripheral wall 60A that surrounds the periphery of the resonator 12. A plurality of openings are formed in the case 60 on the side opposite the base 14 side of the resonator 12, and ultrasonic waves are sent to the outside through these openings and enter the case 60 from the outside.

[0048] At the position where the first guide portion 15A is disposed in the thickness direction of the diaphragm 10, the diameter D1 of an inscribed circle inscribed on the inner peripheral surface of the first through hole 15 is 1.1 times or less the diameter D2 of a circumscribed circle circumscribed on the outer peripheral edge of the first compression coil spring 40 (see FIG. 2). With this configuration, the distance between the first compression coil spring 40 and the first guide portion 15A of the first through hole 15 is narrow, making it easier to accurately position the first compression coil spring 40 by the first through hole 15.

[0049] Furthermore, at the position where the second guide portion 16A is disposed in the thickness direction of the diaphragm 10, the diameter D3 of the inscribed circle inscribed in the inner peripheral surface of the second through hole 16 is 1.1 times or less the diameter D4 of the circumscribed circle circumscribed on the outer peripheral edge of the second compression coil spring 50 (see FIG. 2). With this configuration, the distance between the second compression coil spring 50 and the second guide portion 16A of the second through hole 16 is narrow, making it easier to accurately position the second compression coil spring 50 by the second through hole 16.

[0050] As shown in FIG. 3, 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 of the diaphragm 10 where the amount of displacement in the thickness direction is smallest or where no vibration occurs 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. The piezoelectric element 11 is significantly 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 likely to vibrate than a closed type in which the outer periphery of the diaphragm 10 is fixed. The node 20 is generated inside the outer periphery and outside the center of the diaphragm 10 in a planar direction perpendicular to the thickness direction. The vibration of the diaphragm 10 increases from the node 20 toward the outer periphery and increases from the node 20 toward the center.

[0051] Piezoelectric element 11 has notch 11D cut inward from the outer periphery. When viewed in the thickness direction of diaphragm 10, piezoelectric element 11 has a rectangular shape with notch 11D provided on one side.

[0052] When viewed from the thickness direction, the piezoelectric element 11 is disposed in a position overlapping a portion of the node 20. In other words, when viewed from the thickness direction, the node 20 includes a portion that overlaps with the piezoelectric element 11 and a portion that does not overlap. When viewed from the thickness direction, the piezoelectric element 11 is disposed so as to straddle a portion of the node 20 from the inside to the outside. The cutout portion 11D of the piezoelectric element 11 is cut out so as to straddle a portion of the node 20 from the outside to the inside. In other words, when the diaphragm 10 is viewed from the base portion 14 side, a portion of the node 20 is covered by the piezoelectric element 11, and the other portion of the node 20 is not covered by the piezoelectric element 11.

[0053] Furthermore, an intervening member 13 is bonded to a second surface 22 of the piezoelectric element 11. The intervening member 13 is arranged so that a vibration node 20 of the vibration plate 10 is located between an inscribed circle 13A that inscribes the intervening member 13 and a circumscribed circle 13B that circumscribes the intervening member 13 in a planar direction perpendicular to the thickness direction of the vibration plate 10. The intervening member 13 has a shape that is partially interrupted in the circumferential direction. The intervening member 13 is interrupted in two places. The intervening member 13 is arranged so that, when the vibration plate 10 is viewed from the base portion 14 side, the interrupted portions of the intervening member 13 expose a portion of the node 20 that is not covered by the piezoelectric element 11 and a portion of the piezoelectric element 11 that covers a portion of the node 20.

[0054] The first contact portion 41 is arranged in contact with a portion of the node 20 that is not covered by the piezoelectric element 11. As a result, the first contact portion 41 contacts the first surface 21 of the diaphragm 10 at a position that overlaps the node 20 when viewed from the thickness direction. In addition, a portion of the first contact portion 41 is arranged inside the cutout portion 11D. The second contact portion 51 is arranged in contact with a portion of the piezoelectric element 11 that covers part of the node 20. As a result, the second contact portion 51 contacts the second surface 22 of the diaphragm 10 at a position that overlaps the node 20 when viewed from the thickness direction.

[0055] Furthermore, in a planar direction perpendicular to the thickness direction, the piezoelectric element 11 is disposed in a part of region Z between an inscribed circle 13A inscribed in the interposed member 13 and a circumscribed circle 13B circumscribed therein. That is, region Z includes a first region Z1 in which the piezoelectric element 11 is not disposed and a second region Z2 in which the piezoelectric element 11 is disposed. The first region Z1 is disposed inside the cutout portion 11D of the piezoelectric element 11. The first contact portion 41 contacts the first surface 21 of the diaphragm 10 in the first region Z1. The second contact portion 51 contacts the second surface 22 of the diaphragm 10 in the second region Z2.

[0056] In this way, in the ultrasonic transducer 1, the first contact portion 41 contacts the first surface 21 of the diaphragm 10, and the second contact portion 51 contacts the second surface 22 of the piezoelectric element 11, at positions that overlap with the nodes 20 when viewed from the thickness direction. This makes it difficult for the vibration of the diaphragm 10 to be transmitted to the first contact portion 41 and the second contact portion 51. Furthermore, when the first compression coil spring 40 is joined to the surface of the diaphragm 10 opposite the first surface 21 using lead wires, there are concerns about the labor required for routing the lead wires, reduced connection reliability due to longer lead wires, and changes in vibration frequency due to the lead wires contacting the outer periphery of the diaphragm 10, but these problems do not arise.

[0057] Furthermore, vibration of the diaphragm 10 is suppressed in the annular region to which the intervening member 13 is bonded. In the ultrasonic transducer 1 of the first embodiment, in the region where this vibration is suppressed, that is, in region Z between the inscribed circle 13A inscribed in the intervening member 13 and the circumscribed circle 13B circumscribed therearound, the first contact portion 41 contacts the first surface 21 of the diaphragm 10, and the second contact portion 51 contacts the second surface 22 of the piezoelectric element 11. This makes it difficult for vibration of the diaphragm 10 to be transmitted to the first contact portion 41 and the second contact portion 51. Furthermore, when the first compression coil spring 40 is bonded to the surface of the diaphragm 10 opposite to the first surface 21 using lead wires, there are concerns about the labor required for routing the lead wires, reduced connection reliability due to longer lead wires, and changes in vibration frequency due to the lead wires contacting the outer periphery of the diaphragm 10, but these problems do not arise.

[0058] 2. Second embodiment 4, the ultrasonic transducer 201 of the second embodiment includes a base portion 214. In other respects, the ultrasonic transducer 201 is common to the ultrasonic transducer 1 of the first embodiment.

[0059] The base portion 214 has a first through hole 215 and a second through hole 216 .

[0060] The inner circumferential surface of the first through hole 215 is tapered. The inner circumferential surface of the first through hole 215 is formed such that the inscribed circle inscribed in the inner circumferential surface becomes larger toward the other side in the thickness direction of the diaphragm 10. The inner circumferential surface of the first through hole 215 has a first guide portion 215A where the gap between the inner circumferential surface and the outer circumferential edge of the first compression coil spring 40 is narrowest in the thickness direction, and a first separation portion 215B where the gap between the inner circumferential surface and the outer circumferential edge of the first compression coil spring 40 is larger than that of the first guide portion 215A. This configuration more reliably prevents the first compression coil spring 40 from contacting the inner circumferential surface of the first through hole 215 on the other side in the thickness direction of the diaphragm 10.

[0061] The inner circumferential surface of the second through hole 216 is tapered. The inner circumferential surface of the second through hole 216 is formed such that the inscribed circle inscribed in the inner circumferential surface becomes larger toward the other side in the thickness direction of the diaphragm 10. The inner circumferential surface of the second through hole 216 has a second guide portion 216A where the gap between the inner circumferential surface and the outer circumferential edge of the second compression coil spring 50 is narrowest in the thickness direction, and a second separation portion 216B where the gap between the inner circumferential surface and the outer circumferential edge of the second compression coil spring 50 is larger than that of the second guide portion 216A. This configuration more reliably prevents the second compression coil spring 50 from contacting the inner circumferential surface of the second through hole 216 on the other side in the thickness direction of the diaphragm 10.

[0062] 3. Third embodiment 5, the ultrasonic transducer 301 of the third embodiment includes a base portion 314, a first compression coil spring 340, and a second compression coil spring 350. The ultrasonic transducer 301 is otherwise common to the ultrasonic transducer 1 of the first embodiment.

[0063] The base portion 314 has a first through hole 315 and a second through hole 316 .

[0064] The inner peripheral surface of the first through hole 315 has a first guide portion 315A where the gap between the first through hole 315 and the outer peripheral edge of the first compression coil spring 340 is narrowest in the thickness direction, and a first separation portion 315B where the gap between the first through hole 315 and the outer peripheral edge of the first compression coil spring 340 is larger than that of the first guide portion 315A. The inner peripheral surface of the first through hole 315 is tapered. The inner peripheral surface of the first through hole 315 is formed so that the inscribed circle inscribed in the inner peripheral surface becomes smaller toward the other side in the thickness direction of the diaphragm 10. In contrast, the first compression coil spring 340 is cylindrical. The first compression coil spring 340 has a first contact portion 341 that contacts the first surface 21 of the diaphragm 10 and a third contact portion 342 that contacts the first conductive path 32. First compression coil spring 340 is disposed continuously from one end to the other end of first through hole 315 in the thickness direction of diaphragm 10. That is, of the inner circumferential surface of first through hole 315, the end on the other side in the thickness direction of diaphragm 10 is first guide portion 315A. Also, of the inner circumferential surface of first through hole 315, the portion on one side in the thickness direction of diaphragm 10 of first guide portion 315A is first separating portion 315B.

[0065] According to this configuration, first compression coil spring 340 can be positioned at the position in first through-hole 315 closest to diaphragm 10 .

[0066] The inner peripheral surface of the second through hole 316 has a second guide portion 316A where the gap between the second through hole 316 and the outer peripheral edge of the second compression coil spring 350 is narrowest in the thickness direction, and a second separation portion 316B where the gap between the second through hole 316 and the outer peripheral edge of the second compression coil spring 350 is larger than that of the second guide portion 316A. The inner peripheral surface of the second through hole 316 is tapered. The inner peripheral surface of the second through hole 316 is formed so that the inscribed circle inscribed in the inner peripheral surface becomes smaller toward the other side in the thickness direction of the diaphragm 10. In contrast, the second compression coil spring 350 is cylindrical. The second compression coil spring 350 has a second contact portion 351 that contacts the first surface 21 of the piezoelectric element 11 and a fourth contact portion 352 that contacts the second conductive path 33. Second compression coil spring 350 is disposed continuously from one end to the other end of second through hole 316 in the thickness direction of diaphragm 10. That is, of the inner circumferential surface of second through hole 316, the end on the other side in the thickness direction of diaphragm 10 is second guide portion 316A. Furthermore, of the inner circumferential surface of second through hole 316, the portion on one side in the thickness direction of diaphragm 10 of second guide portion 316A is second separating portion 316B.

[0067] According to this configuration, the second compression coil spring 350 can be positioned at the position in the second through-hole 316 closest to the diaphragm 10 .

[0068] 4. Fourth embodiment 6, the ultrasonic transducer 401 of the fourth embodiment includes the base portion 214 described in the second embodiment, and the first compression coil spring 340 and the second compression coil spring 350 described in the third embodiment. The ultrasonic transducer 401 of the fourth embodiment is common to the ultrasonic transducer 1 of the first embodiment in other respects.

[0069] The inner surface of the first through hole 215 of the base portion 214 has a first guide portion 415A where the gap with the outer edge of the first compression coil spring 340 is narrowest in the thickness direction, and a first separation portion 415B where the gap with the outer edge of the first compression coil spring 340 is larger than that of the first guide portion 415A.

[0070] The inner surface of the second through hole 216 of the base portion 214 has a second guide portion 416A in which the gap between the second through hole 216 and the outer peripheral edge of the second compression coil spring 350 is narrowest in the thickness direction, and a second separation portion 416B in which the gap between the second through hole 216 and the outer peripheral edge of the second compression coil spring 350 is larger than that of the second guide portion 416A.

[0071] 5. Fifth embodiment 7, the ultrasonic transducer 501 of the fifth embodiment includes a base portion 514, and the first compression coil spring 340 and the second compression coil spring 350 described in the third embodiment. The ultrasonic transducer 501 of the fifth embodiment is common to the ultrasonic transducer 1 of the first embodiment in other respects.

[0072] The base portion 514 has a first through hole 515 and a second through hole 516 .

[0073] The inner circumferential surface of first through hole 515 is formed so that the inner circumferential circle inscribed in the inner circumferential surface is smallest at both ends in the thickness direction of diaphragm 10 and large toward the center. More specifically, the inner circumferential surface of first through hole 515 is formed so that the inner circumferential circle inscribed in the inner circumferential surface is smallest at both ends in the thickness direction of diaphragm 10 and large toward the center. In other words, the inner circumferential surface of first through hole 515 has first guide portions 515A at both ends in the thickness direction of diaphragm 10 and has first separating portion 515B in the center. With this configuration, first compression coil spring 340 can be positioned at both ends of first through hole 515.

[0074] The inner circumferential surface of second through hole 516 is formed so that the inner circumferential circle inscribed in the inner circumferential surface is smallest at both ends in the thickness direction of diaphragm 10 and large toward the center. More specifically, the inner circumferential surface of second through hole 516 is formed so that the inner circumferential circle inscribed in the inner circumferential surface is smallest at both ends in the thickness direction of diaphragm 10 and large toward the center. In other words, the inner circumferential surface of second through hole 516 has second guide portions 516A at both ends in the thickness direction of diaphragm 10 and a second separating portion 516B in the center. With this configuration, second compression coil spring 350 can be positioned at both ends of second through hole 516.

[0075] 6. Sixth embodiment 8, the ultrasonic transducer 601 of the sixth embodiment includes a first compression coil spring 640 and a second compression coil spring 650. The ultrasonic transducer 601 of the sixth embodiment is common to the ultrasonic transducer 1 of the sixth embodiment in other respects.

[0076] The first compression coil spring 640 has a plurality of compression coil springs with different sizes of circumscribed circles circumscribing the outer periphery. Specifically, the first compression coil spring 640 has a first small diameter spring 640A and a first large diameter spring 640B. The size of the circumscribed circle of the first small diameter spring 640A circumscribing the outer periphery is smaller than that of the first large diameter spring 640B. The first small diameter spring 640A is disposed closer to the diaphragm 10 than the first large diameter spring 640B. The first small diameter spring 640A has a first contact portion 641 that contacts the first surface 21 of the diaphragm 10. The first small diameter spring 640A is fixed to the first large diameter spring 640B. The first small diameter spring 640A is seamlessly connected to the first large diameter spring 640B. The first large diameter spring 640B has a third contact portion 642 that comes into contact with the first conductive path 32.

[0077] The inner peripheral surface of the first through hole 15 of the base portion 14 has a first guide portion 615A facing the outer peripheral edge of the first large diameter spring 640B, and a first spaced portion 615B facing the outer peripheral edge of the first small diameter spring 640A.

[0078] The second compression coil spring 650 has multiple compression coil springs with different sizes of circumscribed circles circumscribing the outer periphery. Specifically, the second compression coil spring 650 has a second small diameter spring 650A and a second large diameter spring 650B. The second small diameter spring 650A has a circumscribed circle circumscribing the outer periphery that is smaller in size than the second large diameter spring 650B. The second small diameter spring 650A is disposed closer to the piezoelectric element 11 than the second large diameter spring 650B. The second small diameter spring 650A has a second contact portion 651 that contacts the second surface 22 of the piezoelectric element 11. The second small diameter spring 650A is fixed to the second large diameter spring 650B. The second small diameter spring 650A is seamlessly connected to the second large diameter spring 650B. The second large diameter spring 650B has a fourth contact portion 652 that comes into contact with the second conductive path 33.

[0079] The inner peripheral surface of the second through hole 16 of the base portion 14 has a second guide portion 616A facing the outer peripheral edge of the second large diameter spring 650B, and a second spaced portion 616B facing the outer peripheral edge of the second small diameter spring 650A.

[0080] 7. Seventh embodiment 9, the ultrasonic transducer 701 of the seventh embodiment includes a base portion 714, and the first compression coil spring 340 and the second compression coil spring 350 described in the third embodiment. The ultrasonic transducer 701 of the seventh embodiment is common to the ultrasonic transducer 1 of the first embodiment in other respects.

[0081] Base portion 714 has a first through hole 715 and a second through hole 716. The inner peripheral surface of first through hole 715 and the inner peripheral surface of second through hole 716 are stepped in the penetration direction. The inner peripheral surfaces of first through hole 715 and second through hole 716 have inscribed circles that are larger on one side in the thickness direction of diaphragm 10 than on the other side.

[0082] The inner peripheral surface of the first through hole 715 has a first guide portion 715A where the gap between the first through hole 715 and the outer peripheral edge of the first compression coil spring 340 is narrowest in the thickness direction, and a first separating portion 715B where the gap between the first through hole 715 and the outer peripheral edge of the first compression coil spring 340 is larger than that of the first guide portion 715A. The first guide portion 715A is the inner peripheral surface of the small diameter portion of the first through hole 715. The first separating portion 715B is the inner peripheral surface of the large diameter portion of the first through hole 715.

[0083] The inner peripheral surface of the second through hole 716 has a second guide portion 716A where the gap between the second through hole 716 and the outer peripheral edge of the first compression coil spring 340 is narrowest in the thickness direction, and a second separation portion 716B where the gap between the second through hole 716 and the outer peripheral edge of the second compression coil spring 350 is larger than that of the second guide portion 716A. The second guide portion 716A is the inner peripheral surface of the small diameter portion of the second through hole 716. The second separation portion 716B is the inner peripheral surface of the large diameter portion of the second through hole 716.

[0084] 8. Eighth embodiment 10, the ultrasonic transducer 801 of the eighth embodiment includes a base portion 814, and the first compression coil spring 340 and the second compression coil spring 350 described in the third embodiment. The ultrasonic transducer 801 of the eighth embodiment is common to the ultrasonic transducer 1 of the first embodiment in other respects.

[0085] Base portion 814 has a first through hole 815 and a second through hole 816. The inner peripheral surface of first through hole 815 and the inner peripheral surface of second through hole 816 are stepped in the penetration direction. The inner peripheral surfaces of first through hole 815 and second through hole 816 have inscribed circles that are inscribed in the inner peripheral surfaces and are smaller on one side in the thickness direction of diaphragm 10 than on the other side.

[0086] The inner peripheral surface of the first through hole 815 has a first guide portion 815A where the gap between the first through hole 815 and the outer peripheral edge of the first compression coil spring 340 is narrowest in the thickness direction, and a first separating portion 815B where the gap between the first through hole 815 and the outer peripheral edge of the first compression coil spring 340 is larger than that of the first guide portion 815A. The first guide portion 815A is the inner peripheral surface of the small diameter portion of the first through hole 815. The first separating portion 815B is the inner peripheral surface of the large diameter portion of the first through hole 815.

[0087] The inner peripheral surface of the second through hole 816 has a second guide portion 816A where the gap between the second through hole 816 and the outer peripheral edge of the first compression coil spring 340 is narrowest in the thickness direction, and a second separation portion 816B where the gap between the second through hole 816 and the outer peripheral edge of the second compression coil spring 350 is larger than that of the second guide portion 816A. The second guide portion 816A is the inner peripheral surface of the small diameter portion of the second through hole 816. The second separation portion 816B is the inner peripheral surface of the large diameter portion of the second through hole 816.

[0088] 9. Ninth embodiment 11, the ultrasonic transducer 901 of the ninth embodiment includes the base portion 814 described in the eighth embodiment, and the first compression coil spring 40 and the second compression coil spring 50 described in the first embodiment. The ultrasonic transducer 901 of the ninth embodiment is common to the ultrasonic transducer 1 of the first embodiment in other respects.

[0089] The inner surface of the first through hole 815 of the base portion 814 has a first guide portion 915A in which the gap between the first through hole 815 and the outer peripheral edge of the first compression coil spring 40 is narrowest in the thickness direction, and a first separation portion 915B in which the gap between the first through hole 815 and the outer peripheral edge of the first compression coil spring 40 is larger than that of the first guide portion 915A.

[0090] The inner surface of the second through hole 816 of the base portion 814 has a second guide portion 916A in which the gap with the outer edge of the second compression coil spring 50 is narrowest in the thickness direction, and a second separation portion 916B in which the gap with the outer edge of the second compression coil spring 50 is larger than that of the second guide portion 916A.

[0091] <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 manner as long as they are not contradictory.

[0092] 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]

[0093] 1...Ultrasonic transducer 10…Diaphragm 11...Piezoelectric element 11A...Piezoelectric body 11B...Electrode 11C...Electrode 11D...Notch 12...Resonator 13…Intervening member 13A...Inscribed circle inscribed in the intervening member 13B...Circumscribed circle circumscribing the intervening member 14...Base 15...First through hole 15A...First guide section 15B...First separation part 16...Second through hole 16A...Second guide section 16B…Second separation part Section 20... 21...Side 1 22…Second side 30...Circuit board 31...Board body 32...First conductive path 33...Second conductive path 40...First compression coil spring 41...First contact part 42...Third contact point 50...Second compression coil spring 51...Second contact part 52...Fourth contact point 60…cases 60A...peripheral wall part 201...Ultrasonic transducer 214...Base 215...First through hole 215A...First guide section 215B...First separation part 216...Second through hole 216A...Second guide section 216B…Second separation part 301...Ultrasonic transducer 314...Base 315...First through hole 315A...First guide section 315B...First separation part 316...Second through hole 316A...Second guide section 316B…Second separation part 340...First compression coil spring 341...First contact point 342...Third contact point 350...Second compression coil spring 351...Second contact part 352...Fourth contact point 401...Ultrasonic transducer 415A...First guide section 415B…First separation part 416A...Second guide section 416B…Second separation part 501...Ultrasonic transducer 514...Base 515...First through hole 515A...First guide section 515B…First separation part 516...Second through hole 516A...Second guide section 516B…Second separation part 601...Ultrasonic transducer 615A...First guide section 615B...First separation part 616A...Second guide section 616B…Second separation part 640...First compression coil spring 640A...First small diameter spring 640B...First large diameter spring 641...First contact point 642...Third contact point 650...Second compression coil spring 650A...Second small diameter spring 650B...Second large diameter spring 651...Second contact point 652...Fourth contact point 701...Ultrasonic transducer 714...Base 715...First through hole 715A...First guide section 715B…First separation part 716...Second through hole 716A...Second guide section 716B…Second separation part 801...Ultrasonic transducer 814...Base 815...First through hole 815A...First guide section 815B…First separation part 816...Second through hole 816A...Second guide section 816B…Second separation part 901...Ultrasonic transducer 915A...First guide section 915B...First separation part 916A...Second guide section 916B…Second separation part D1: Diameter of the inscribed circle inscribed on the inner circumferential surface of the first through hole D2: Diameter of the circumscribed circle that circumscribes the outer edge of the first compression coil spring D3: Diameter of the inscribed circle inscribed on the inner surface of the second through hole D4: Diameter of the circumscribed circle that circumscribes the outer edge of the third compression coil spring Z: The area between the inscribed circle inscribed in the intervening member and the circumscribed circle Z1…1st area Z2…Second area

Claims

1. a conductive diaphragm that vibrates to generate annular nodes; a piezoelectric element bonded to a part of a first surface on one side of the vibration plate in a thickness direction; a first compression coil spring having a first contact portion that contacts the first surface of the diaphragm; a second compression coil spring having a second contact portion that contacts a second surface of the piezoelectric element opposite to the vibration plate side; a circuit board having a first conductive path in contact with a third contact portion of the first compression coil spring opposite to the first contact portion, and a second conductive path in contact with a fourth contact portion of the second compression coil spring opposite to the second contact portion; a base portion having a first through hole penetrating in the thickness direction and a second through hole penetrating in the thickness direction, the base portion being disposed between the piezoelectric element and the circuit board; Equipped with At least a portion of the first compression coil spring is disposed within the first through hole, At least a portion of the second compression coil spring is disposed within the second through hole, the first contact portion contacts the first surface of the diaphragm at a position overlapping the node when viewed from the thickness direction; the second contact portion is an ultrasonic transducer that contacts the second surface of the piezoelectric element at a position that overlaps the node when viewed from the thickness direction, an inner peripheral surface of the first through hole has a first guide portion where a gap between the inner peripheral surface and an outer peripheral edge of the first compression coil spring is narrowest in the thickness direction, and a first separation portion where a gap between the inner peripheral surface and the outer peripheral edge of the first compression coil spring is larger than that between the inner peripheral surface and the first guide portion; The inner peripheral surface of the second through hole has a second guide portion where the gap between the second through hole and the outer peripheral edge of the second compression coil spring is narrowest in the thickness direction, and a second separation portion where the gap between the second through hole and the outer peripheral edge of the second compression coil spring is larger than that between the second guide portion and the outer peripheral edge of the second compression coil spring. Ultrasonic transducer.

2. a diameter of an inscribed circle inscribed on an inner circumferential surface of the first through hole at a position in the thickness direction where the first guide portion is disposed is 1.1 times or less a diameter of a circumscribed circle circumscribed on an outer circumferential edge of the first compression coil spring, At a position in the thickness direction where the second guide portion is disposed, a diameter of an inscribed circle inscribed in the inner circumferential surface of the second through hole is 1.1 times or less the diameter of a circumscribed circle circumscribed on an outer circumferential edge of the second compression coil spring.

2. The ultrasonic transducer of claim 1.

3. the first guide portion is provided at one end of the first through hole in the thickness direction, the third contact portion of the first compression coil spring is disposed at the same position as the first guide portion in the thickness direction, the second guide portion is provided at one end of the second through hole in the thickness direction, The fourth contact portion of the second compression coil spring is disposed at the same position as the second guide portion in the thickness direction.

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

4. The outer shape of the first compression coil spring is formed to become smaller toward the other side in the thickness direction, The outer shape of the second compression coil spring is formed to become smaller toward the other side in the thickness direction.

4. The ultrasonic transducer according to claim 3.

5. an inner circumferential surface of the first through hole is formed such that an inscribed circle inscribed in the inner circumferential surface becomes larger toward the other side in the thickness direction, The inner circumferential surface of the second through hole is formed so that an inscribed circle inscribed in the inner circumferential surface becomes larger toward the other side in the thickness direction.

4. The ultrasonic transducer according to claim 3.

6. the first guide portion is provided at an end portion on the other side in the thickness direction of the first through hole, The second guide portion is provided at the other end of the second through hole in the thickness direction.

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

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