Ultrasonic wave generation device

Abstract

An ultrasonic wave generation device (10) comprises an ultrasonic wave generation source (11), an ultrasonic wave focusing part (12), and a waveguide (13). The ultrasonic wave focusing part (12) has a first reflection surface (21) that reflects ultrasonic waves generated by the ultrasonic wave generation source (11), and a second reflection surface (22) that reflects the ultrasonic waves reflected by the first reflection surface (21). The ultrasonic wave generation source (11) generates ultrasonic waves of longitudinal waves. The ultrasonic wave generation device (10) is configured such that the ultrasonic waves of longitudinal waves generated from the ultrasonic wave generation source (11) are converted to transverse waves when reflected by the first reflection surface (21) and move toward a first focal point (F1). The second reflection surface (22) is positioned on a path in which the ultrasonic waves converted to transverse waves by the first reflection surface (21) move toward the first focal point (F1). The ultrasonic wave generation device (10) is configured such that the ultrasonic waves converted to transverse waves by the first reflection surface (21) are reflected by the second reflection surface (22) while remaining as transverse waves and are introduced into the waveguide (13).

Description

ultrasonic generator

[0001] The present invention relates to an ultrasonic generator.

[0002] Patent Document 1 discloses an ultrasonic irradiator. This ultrasonic irradiator includes an ultrasonic transducer and an acoustic propagation body that propagates ultrasonic waves from the ultrasonic transducer. The acoustic propagation body includes a main body and a shaft extending forward from the front surface of the main body. The front surface of the main body functions as a concave primary reflecting surface that reflects ultrasonic waves from the ultrasonic transducer. The main body has a flat rear surface to which the ultrasonic transducer is joined. The main body has a well connected to the rear surface. The bottom surface of the well functions as a concave secondary reflecting surface that reflects the primary reflected wave from the primary reflecting surface. The secondary reflected wave from the secondary reflecting surface propagates through the shaft and is irradiated forward from the tip surface of the shaft.

[0003] Patent No. 6774697

[0004] In the technology of Patent Document 1, longitudinal waves and transverse waves are generated when the primary reflecting surface (first reflecting surface) reflects ultrasonic waves from the ultrasonic transducer. However, Patent Document 1 does not consider utilizing the transverse waves generated at the primary reflecting surface (first reflecting surface).

[0005] An object of the present invention is to provide a technique that can introduce ultrasonic waves into a waveguide by utilizing a transverse wave generated at a first reflecting surface.

[0006] The ultrasonic generator of the present disclosure comprises an ultrasonic generating source that generates ultrasonic waves, an ultrasonic focusing unit that focuses the ultrasonic waves generated from the ultrasonic generating source, and a waveguide that transmits the ultrasonic waves focused by the ultrasonic focusing unit, wherein the ultrasonic focusing unit has a first reflecting surface that reflects the ultrasonic waves generated by the ultrasonic generating source, and a second reflecting surface that reflects the ultrasonic waves reflected by the first reflecting surface, wherein the ultrasonic generating source generates the ultrasonic waves in the form of longitudinal waves, and the ultrasonic generator is configured such that the ultrasonic waves in the form of longitudinal waves generated from the ultrasonic generating source are converted into shear waves when reflected by the first reflecting surface and directed toward a first focal point, the second reflecting surface is located on a path along which the ultrasonic waves converted into shear waves at the first reflecting surface are directed toward the first focal point, and the ultrasonic generator is configured such that the ultrasonic waves converted into shear waves at the first reflecting surface are reflected as shear waves at the second reflecting surface and directed into the waveguide.

[0007] According to the present disclosure, ultrasonic waves can be introduced into the waveguide by utilizing the transverse waves generated at the first reflecting surface.

[0008] FIG. 1 is a cross-sectional view of an ultrasonic generator according to a first embodiment. FIG. 2 is a plan view of the ultrasonic generator according to the first embodiment. FIG. 3 is an explanatory diagram conceptually showing how ultrasonic waves are propagated. FIG. 4 is a graph showing the relationship between the angle of incidence and the energy conversion rate from longitudinal waves to shear waves. FIG. 5 is a graph showing the relationship between the angle of incidence and the energy maintenance rate when the wave is reflected as a shear wave. FIG. 6 is a perspective view of an ultrasonic generator according to a second embodiment. FIG. 7 shows a first modified example of the cross-sectional shape of an ultrasonic generator. FIG. 8 shows a second modified example of the cross-sectional shape of an ultrasonic generator.

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

[0010] [1] An ultrasonic generator comprising: an ultrasonic generating source that generates ultrasonic waves; an ultrasonic focusing unit that focuses the ultrasonic waves generated by the ultrasonic generating source; and a waveguide that transmits the ultrasonic waves focused by the ultrasonic focusing unit, wherein the ultrasonic focusing unit has: a first reflecting surface that reflects the ultrasonic waves generated by the ultrasonic generating source; and a second reflecting surface that reflects the ultrasonic waves reflected by the first reflecting surface, wherein the ultrasonic generating source generates the ultrasonic waves in the form of longitudinal waves; the ultrasonic generator is configured such that the ultrasonic waves in the form of longitudinal waves generated by the ultrasonic generating source are converted into shear waves when reflected by the first reflecting surface and directed toward a first focal point; the second reflecting surface is located on a path along which the ultrasonic waves converted into shear waves at the first reflecting surface are directed toward the first focal point; and the ultrasonic generator is configured such that the ultrasonic waves converted into shear waves at the first reflecting surface are reflected as shear waves at the second reflecting surface and directed into the waveguide.

[0011] The ultrasonic generator can convert longitudinal ultrasonic waves generated from an ultrasonic source into transverse ultrasonic waves directed toward a first focal point by reflecting them at a first reflecting surface. Moreover, the ultrasonic generator can reflect the transverse waves directed toward the first focal point as transverse waves at a second reflecting surface and guide them into a waveguide. In other words, the ultrasonic generator can guide ultrasonic waves into a waveguide by utilizing the transverse waves generated at the first reflecting surface.

[0012] [2] The ultrasonic wave generating source has a one-side generating unit arranged on one side of the waveguide and an other-side generating unit arranged on the other side of the waveguide in a first direction orthogonal to the direction in which the ultrasonic wave generating source generates the ultrasonic waves; the first reflecting surface has a first one-side reflecting surface arranged on one side of the waveguide and a first other-side reflecting surface arranged on the other side of the waveguide in the first direction; the second reflecting surface has a second one-side reflecting surface arranged on one side of the waveguide and a second other-side reflecting surface arranged on the other side of the waveguide in the first direction; the one-side generating unit generates the ultrasonic waves of longitudinal waves; the ultrasonic generator is configured so that the ultrasonic waves of longitudinal waves generated from the one-side generating unit are converted into shear waves when reflected by the first one-side reflecting surface and directed toward the first focal point; and the second one-side reflecting surface is located on a path along which the ultrasonic waves converted into shear waves by the first one-side reflecting surface are directed toward the first focal point; The ultrasonic generator is configured such that the ultrasonic waves converted into shear waves at the first one-side reflecting surface are reflected as shear waves at the second one-side reflecting surface and introduced into the waveguide; the other-side generating unit generates the ultrasonic waves in longitudinal waves; the ultrasonic generator is configured such that the ultrasonic waves in longitudinal waves generated from the other-side generating unit are converted into shear waves when reflected at the first other-side reflecting surface and directed toward the first focal point; the second other-side reflecting surface is located on a path along which the ultrasonic waves converted into shear waves at the first other-side reflecting surface are directed toward the first focal point; and the ultrasonic generator is configured such that the ultrasonic waves converted into shear waves at the first other-side reflecting surface are reflected as shear waves at the second other-side reflecting surface and introduced into the waveguide.

[0013] The ultrasonic generator can introduce ultrasonic waves into the waveguide by using the transverse waves generated at the first one-side reflecting surface and the first other-side reflecting surface, i.e., the ultrasonic generator can introduce ultrasonic waves into the waveguide from both sides in the first direction by using the transverse waves generated at the first reflecting surface.

[0014] [3] The ultrasonic generator according to [1] or [2] is configured such that the ultrasonic waves converted into shear waves at the first reflecting surface are reflected as shear waves at the second reflecting surface, directed toward the second focal point, and introduced into the waveguide.

[0015] The ultrasonic generator can reflect the transverse wave traveling toward the first focal point by the second reflecting surface so that the transverse wave remains as a transverse wave and travels toward the second focal point.

[0016] [4] The ultrasonic generator according to [3], wherein the second focal point is located between the base end of the waveguide and the second reflecting surface.

[0017] The ultrasonic generator can focus the ultrasonic waves reflected by the second reflecting surface as shear waves at the second focal point before the waveguide.

[0018] [5] The ultrasonic generator described in any one of [1] to [4], wherein the second reflecting surface includes a reflection point at which the energy retention rate when the ultrasonic waves converted into shear waves by the first reflecting surface are reflected as shear waves is 90% or more.

[0019] The ultrasonic wave generator can maintain 90% or more of the energy when the shear wave is reflected as it is by the second reflecting surface.

[0020] [6] The ultrasonic generator according to [5], wherein the Poisson's ratio of the material constituting the second reflecting surface is 0.17 or more and 0.34 or less, and the second reflecting surface includes a reflection point at which the incident angle of the transverse wave generated by the ultrasonic generating source is 39.1° or more and less than 90°.

[0021] In the above ultrasonic generator, when the Poisson's ratio of the material constituting the second reflecting surface is 0.17 or more and 0.34 or less, the energy can be maintained at 90% or more when the shear wave is reflected as is by the second reflecting surface.

[0022] [7] The ultrasonic generating source, the ultrasonic focusing unit, and the waveguide are shaped to extend in a second direction perpendicular to the first direction among directions perpendicular to the direction in which the ultrasonic generating source generates the ultrasonic waves. An ultrasonic generating device described in any one of [2] to [6] that directly or indirectly cites [2].

[0023] The ultrasonic generator can introduce ultrasonic waves into the waveguide over a wide range in the second direction by utilizing the transverse waves generated at the first reflecting surface.

[0024] [Details of the embodiment of the present disclosure] The ultrasonic generator of the present disclosure is used in, for example, an ultrasonic diagnostic device, an ultrasonic treatment device, a cavitation generator, a dental scaler, a blood coagulation cutting device (e.g., an ultrasonic scalpel), an ultrasonic processing machine, an ultrasonic cleaning machine (e.g., an ultrasonic cleaner), etc.

[0025] 1 and 2 , an ultrasonic generator 10 includes an ultrasonic source 11, an ultrasonic focusing unit 12, and a waveguide 13. The ultrasonic source 11, the ultrasonic focusing unit 12, and the waveguide 13 are symmetrical about an axis C. The axis C is the front-rear direction of the ultrasonic generator 10.

[0026] The ultrasonic wave generating source 11 generates ultrasonic waves. The ultrasonic wave generating source 11 is composed of, for example, a piezoelectric element. The piezoelectric element has a piezoelectric body made of piezoelectric ceramics and electrodes arranged on both sides of the piezoelectric body. The ultrasonic wave generating source 11 is plate-shaped. The ultrasonic wave generating source 11 has a thickness. The thickness direction of the ultrasonic wave generating source 11 is the stacking direction of the piezoelectric body and the electrodes. The ultrasonic wave generating source 11 generates ultrasonic waves when an AC voltage based on a power source P is applied. The ultrasonic wave generating source 11 generates ultrasonic waves at a frequency of, for example, 30 kHz or more and 10 MHz or less. The ultrasonic wave generating source 11 generates ultrasonic waves in its thickness direction. The ultrasonic wave generating source 11 generates ultrasonic waves forward. The ultrasonic wave generating source 11 is bonded to the rear surface of the ultrasonic focusing unit 12.

[0027] The ultrasonic focusing unit 12 focuses ultrasonic waves generated by the ultrasonic generating source 11. The ultrasonic focusing unit 12 is formed of, for example, metal (e.g., duralumin). The ultrasonic focusing unit 12 has a first reflecting surface 21 and a second reflecting surface 22. The first reflecting surface 21 is disposed forward of the ultrasonic generating source 11. The first reflecting surface 21 reflects ultrasonic waves generated by the ultrasonic generating source 11 toward the second reflecting surface 22. A hole 12A is formed in the center of the rear surface of the ultrasonic focusing unit 12. The second reflecting surface 22 is formed at the bottom of the hole 12A. The second reflecting surface 22 is disposed opposite the first reflecting surface 21. The second reflecting surface 22 is disposed rearward of the front end of the first reflecting surface 21. The second reflecting surface 22 is disposed forward of the rear end of the first reflecting surface 21. The second reflecting surface 22 reflects the ultrasonic waves reflected by the first reflecting surface 21 toward the base end (specifically, the rear end) of the waveguide 13 .

[0028] A recess 23 is formed in the ultrasonic focusing section 12. The recess 23 is recessed from the first reflecting surface 21 toward the second reflecting surface 22 along the outer circumferential surface of the waveguide 13. The recess 23 is formed continuously around the entire periphery.

[0029] The waveguide 13 transmits the ultrasonic waves focused by the ultrasonic focusing unit 12. The waveguide 13 has a columnar (e.g., cylindrical) shape extending forward from the front end of the ultrasonic focusing unit 12. The waveguide 13 extends along the axis C. In this embodiment, the waveguide 13 is parallel to the axis C, but it does not have to be parallel. For example, the waveguide 13 may be slightly inclined with respect to the axis C, or may be bent midway.

[0030] The waveguide 13 may be a separate member from the ultrasonic focusing unit 12, or may be the same member as the ultrasonic focusing unit 12. The waveguide 13 is preferably formed from a material with high ultrasonic propagation properties, such as an aluminum alloy or metallic glass. The waveguide 13 may also be formed from a shape memory alloy, such as an alloy of titanium and nickel. The waveguide 13 is elastically deformable.

[0031] As shown in FIG. 3 , the ultrasonic wave source 11 generates longitudinal ultrasonic waves. These longitudinal waves are incident on the first reflecting surface 21. When the longitudinal waves generated by the ultrasonic wave source 11 are reflected by the first reflecting surface 21, longitudinal waves and shear waves are generated. FIG. 3 shows the path of the shear waves generated by the first reflecting surface 21. The reflection angle of the longitudinal waves generated by the first reflecting surface 21 is the same as the incident angle of the longitudinal waves incident on the first reflecting surface 21. The reflection angle θ2 of the shear waves generated by the first reflecting surface 21 is smaller than the incident angle θ1 of the longitudinal waves incident on the first reflecting surface 21. This relationship follows Snell's law. In other words, because the propagation velocity of shear waves is smaller than the propagation velocity of longitudinal waves, the reflection angle of the shear waves generated by the first reflecting surface 21 is smaller than the incident angle of the longitudinal waves incident on the first reflecting surface 21.

[0032] 4, the energy conversion rate from longitudinal waves to shear waves at first reflecting surface 21 varies depending on the Poisson's ratio of the material constituting first reflecting surface 21 and the angle of incidence of the longitudinal waves. First reflecting surface 21 includes reflection points where the energy conversion rate from longitudinal waves to shear waves is 50% or more. For example, at reflection points (e.g., reflection points 25A and 25B) where the Poisson's ratio of the material constituting first reflecting surface 21 is 0.17 or more and 0.34 or less and the angle of incidence of the longitudinal waves is 40° or more and 85° or less, the energy conversion rate from longitudinal waves to shear waves is generally 50% or more.

[0033] The first reflecting surface 21 is curved so that the transverse waves generated on the first reflecting surface 21 are converged at a first focal point F1. For example, the first reflecting surface 21 has a shape along an ellipse, and the ratio of the major axis to the minor axis of the ellipse satisfies the condition of the following formula (1). Major axis: minor axis = CDA: √(CDA ２ -CTA ２ ) ...Equation (1) CDA is the propagation velocity of the longitudinal wave incident on the first reflecting surface 21. CTA is the propagation velocity of the transverse wave generated at the first reflecting surface 21. According to this configuration, the transverse wave generated at the first reflecting surface 21 is concentrated at the first focal point F1.

[0034] The shear waves generated at the first reflecting surface 21 are incident on the second reflecting surface 22. The second reflecting surface 22 is located on a path along which the ultrasonic waves converted into shear waves at the first reflecting surface 21 travel toward the first focal point F1. The second reflecting surface 22 is curved so as to reflect the ultrasonic waves converted into shear waves at the first reflecting surface 21 toward the waveguide 13 as shear waves. Furthermore, the second reflecting surface 22 is curved so as to focus the ultrasonic waves reflected as shear waves. The second reflecting surface 22 is curved so as to focus the ultrasonic waves reflected as shear waves at the second focal point F2. The second focal point F2 is located between the base end of the waveguide 13 and the second reflecting surface 22. It is preferable that the distance between the base end of the waveguide 13 and the second focal point F2 is less than half the shortest distance between the base end of the waveguide 13 and the second reflecting surface 22. In the example shown in Figure 3, the shortest distance between the base end of the waveguide 13 and the second reflecting surface 22 is the shortest distance between positions 26A, 26B where longitudinal ultrasonic waves generated from the innermost part of the annular ultrasonic generating source 11 are converted into transverse waves by the first reflecting surface 21 and incident on the second reflecting surface 22, and the center of the base end of the waveguide 13.

[0035] As shown in Fig. 5 , the energy retention rate when a shear wave is reflected as it is by the second reflecting surface 22 varies depending on the Poisson's ratio of the material constituting the second reflecting surface 22 and the angle of incidence of the shear wave. When a shear wave incident on the second reflecting surface 22 is reflected as it is, the angle of incidence θ3 of the shear wave incident on the second reflecting surface 22 is the same as the angle of reflection θ4 of the shear wave reflected by the second reflecting surface 22. The second reflecting surface 22 includes a reflection point where the energy retention rate when the shear wave is reflected as it is is 90% or more. For example, at a reflection point where the Poisson's ratio of the material constituting the second reflecting surface 22 is 0.17 or more and 0.34 or less and the angle of incidence of the shear wave is 39.1° or more and less than 90° (e.g., reflection points 27A and 27B shown in Fig. 3 ), the energy retention rate when the shear wave is reflected as it is is 90% or more.

[0036] In this manner, the ultrasonic source 11 generates longitudinal ultrasonic waves. The ultrasonic generator 10 is configured so that when longitudinal ultrasonic waves generated from the ultrasonic source 11 are reflected by the first reflecting surface 21, they are converted into shear waves and directed toward the first focal point F1. The second reflecting surface 22 is located on a path along which the ultrasonic waves converted into shear waves by the first reflecting surface 21 travel toward the first focal point F1. The ultrasonic generator 10 is configured so that the ultrasonic waves converted into shear waves by the first reflecting surface 21 are reflected as shear waves by the second reflecting surface 22, focused, and introduced into the waveguide 13. With this configuration, the ultrasonic generator 10 can convert longitudinal ultrasonic waves generated from the ultrasonic source 11 into shear ultrasonic waves directed toward the first focal point F1 by reflecting them by the first reflecting surface 21. Moreover, the ultrasonic generator 10 can reflect shear waves directed toward the first focal point F1 by the second reflecting surface 22 and direct them into the waveguide 13. That is, the ultrasonic generator 10 can introduce ultrasonic waves into the waveguide 13 by using the transverse waves generated at the first reflecting surface 21 .

[0037] Furthermore, the ultrasonic generator 10 is configured so that the ultrasonic waves converted into shear waves by the first reflecting surface 21 are reflected as shear waves by the second reflecting surface 22, proceed toward the second focal point F2, and are introduced into the waveguide 13. With this configuration, the ultrasonic generator 10 can reflect the shear waves proceeding toward the first focal point F1 by the second reflecting surface 22 so that the shear waves proceed toward the second focal point F2.

[0038] The second focal point F2 is located between the base end of the waveguide 13 and the second reflecting surface 22. With this configuration, the ultrasonic generator 10 can focus the ultrasonic waves reflected as shear waves by the second reflecting surface 22 onto the second focal point F2 just before the waveguide 13.

[0039] Furthermore, the second reflecting surface 22 includes a reflection point at which the energy retention rate when the ultrasonic waves converted into shear waves by the first reflecting surface 21 are reflected as shear waves is 90% or more. With this configuration, the ultrasonic generator 10 can maintain 90% or more of the energy when the ultrasonic waves are reflected as shear waves by the second reflecting surface 22.

[0040] Furthermore, the Poisson's ratio of the material constituting the second reflecting surface 22 is equal to or greater than 0.17 and equal to or less than 0.34. The second reflecting surface 22 includes a reflection point at which the angle of incidence of the shear wave generated by the ultrasonic wave source 11 is equal to or greater than 39.1° and less than 90°. With this configuration, the ultrasonic generator 10 can maintain 90% or more of the energy when the shear wave is reflected as is by the second reflecting surface 22 in a configuration in which the Poisson's ratio of the material constituting the second reflecting surface 22 is equal to or greater than 0.17 and equal to or less than 0.34.

[0041] In addition, the ultrasonic generator 10 focuses the ultrasonic waves generated from the ultrasonic source 11 and introduces them into the waveguide 13, making it suitable for generating burst waves by intermittently driving the ultrasonic source 11.

[0042] 1, the ultrasonic wave generating source 11 further includes a one-side generating unit 11A disposed on one side of the waveguide 13 in a first direction, and a other-side generating unit 11B disposed on the other side of the waveguide 13. The first direction is a direction perpendicular to the direction in which the ultrasonic wave generating source 11 generates ultrasonic waves. In this embodiment, the one-side generating unit 11A and the other-side generating unit 11B are formed of the same member, but may be formed of different members.

[0043] The first reflecting surface 21 has a first one-side reflecting surface 21A arranged on one side of the waveguide 13 in the first direction, and a first other-side reflecting surface 21B arranged on the other side of the waveguide 13.

[0044] The second reflecting surface 22 has a second one-side reflecting surface 22A arranged on one side of the waveguide 13 in the first direction, and a second other-side reflecting surface 22B arranged on the other side of the waveguide 13.

[0045] As shown in Fig. 3, the one-side generating unit 11A generates longitudinal ultrasonic waves. These longitudinal waves are incident on the first one-side reflecting surface 21A. When the longitudinal waves generated by the one-side generating unit 11A are reflected by the first one-side reflecting surface 21A, longitudinal waves and shear waves are generated. The reflection angle of the shear waves generated by the first one-side reflecting surface 21A is smaller than the incidence angle of the longitudinal waves incident on the first one-side reflecting surface 21A. The first one-side reflecting surface 21A is curved so that the shear waves generated by the first one-side reflecting surface 21A are concentrated at a first focal point F1.

[0046] The shear waves generated by the first one-side reflecting surface 21A are incident on the second one-side reflecting surface 22A. The second one-side reflecting surface 22A is located on a path of the ultrasonic waves converted into shear waves by the first one-side reflecting surface 21A toward the first focal point F1. The second one-side reflecting surface 22A is curved so as to reflect the ultrasonic waves converted into shear waves by the first one-side reflecting surface 21A toward the waveguide 13 as shear waves. Furthermore, the second one-side reflecting surface 22A is curved so as to focus the ultrasonic waves reflected as shear waves. The second one-side reflecting surface 22A is curved so as to focus the ultrasonic waves reflected as shear waves at the second focal point F2. The second focal point F2 is located between the base end of the waveguide 13 and the second one-side reflecting surface 22A. The second one-side reflecting surface 22A includes a reflection point 27A at which the energy retention rate when reflected as shear waves is 90% or more.

[0047] The other-side generating unit 11B generates longitudinal ultrasonic waves. These longitudinal waves are incident on the first other-side reflecting surface 21B. When the longitudinal waves generated by the other-side generating unit 11B are reflected by the first other-side reflecting surface 21B, longitudinal waves and transverse waves are generated. The reflection angle of the transverse waves generated by the first other-side reflecting surface 21B is smaller than the incident angle of the longitudinal waves incident on the first other-side reflecting surface 21B. The first other-side reflecting surface 21B is curved so that the transverse waves generated by the first other-side reflecting surface 21B are concentrated at a first focal point F1.

[0048] The shear waves generated by the first other-side reflecting surface 21B are incident on the second other-side reflecting surface 22B. The second other-side reflecting surface 22B is located on a path along which the ultrasonic waves converted into shear waves by the first other-side reflecting surface 21B travel toward the first focal point F1. The second other-side reflecting surface 22B is curved so as to reflect the ultrasonic waves converted into shear waves by the first other-side reflecting surface 21B toward the waveguide 13 as shear waves. Furthermore, the second other-side reflecting surface 22B is curved so as to focus the ultrasonic waves reflected as shear waves. The second other-side reflecting surface 22B is curved so that the ultrasonic waves reflected as shear waves converge at the second focal point F2. The second focal point F2 is located between the base end of the waveguide 13 and the second other-side reflecting surface 22B. The second other-side reflecting surface 22B includes a reflection point 27B at which the energy retention rate when the ultrasonic waves are reflected as shear waves is 90% or more.

[0049] The first one-side reflecting surface 21A and the first other-side reflecting surface 21B have a shape along the same ellipse that satisfies the above-mentioned formula (1).

[0050] In this way, the one-side generating unit 11A generates longitudinal ultrasonic waves. The ultrasonic generator 10 is configured so that longitudinal ultrasonic waves generated from the one-side generating unit 11A are converted into shear waves when reflected by the first one-side reflecting surface 21A and directed toward the first focal point F1. The second one-side reflecting surface 22A is located on a path along which the ultrasonic waves converted into shear waves by the first one-side reflecting surface 21A are directed toward the first focal point F1. The ultrasonic generator 10 is configured so that the ultrasonic waves converted into shear waves by the first one-side reflecting surface 21A are reflected as shear waves by the second one-side reflecting surface 22A, focused, and introduced into the waveguide 13. The other-side generating unit 11B generates longitudinal ultrasonic waves. The ultrasonic generator 10 is configured so that longitudinal ultrasonic waves generated from the other-side generating unit 11B are converted into shear waves when reflected by the first other-side reflecting surface 21B and directed toward the first focal point F1. The second other-side reflecting surface 22B is located on a path along which the ultrasonic waves converted into shear waves by the first other-side reflecting surface 21B travel toward the first focal point F1. The ultrasonic generator 10 is configured so that the ultrasonic waves converted into shear waves by the first other-side reflecting surface 21B are reflected as shear waves by the second other-side reflecting surface 22B, focused, and introduced into the waveguide 13. With this configuration, the ultrasonic generator 10 can introduce ultrasonic waves into the waveguide 13 using the shear waves generated by the first one-side reflecting surface 21A and the first other-side reflecting surface 21B. That is, the ultrasonic generator 10 can introduce ultrasonic waves into the waveguide 13 from both sides in the first direction using the shear waves generated by the first reflecting surface 21A. Furthermore, the shear wave ultrasonic waves traveling toward the waveguide 13 from both sides in the first direction are introduced into the waveguide 13, which forms a narrow waveguide path, and are converted into longitudinal wave ultrasonic waves traveling in the direction along the axis C. The converted longitudinal wave ultrasonic waves are introduced into the waveguide 13 and transmitted through the waveguide 13.

[0051] 2. Second Embodiment In the first embodiment, an example in which the ultrasonic generator is axially symmetrical has been described, whereas in the second embodiment, an example in which the ultrasonic generator is plane symmetrical will be described.

[0052] As shown in Fig. 6, an ultrasonic generator 210 of the second embodiment includes an ultrasonic wave generating source 211, an ultrasonic wave focusing unit 212, and a waveguide 213. The cross-sectional views of the ultrasonic wave generating source 211, the ultrasonic wave focusing unit 212, and the waveguide 213 are the same as the cross-sectional view shown in Fig. 1. The ultrasonic wave generating source 211, the ultrasonic wave focusing unit 212, and the waveguide 213 have shapes obtained by extending the cross-sectional shape shown in Fig. 1 in a second direction perpendicular to the cross section shown in Fig. 1. In other words, the ultrasonic wave generating source 211, the ultrasonic wave focusing unit 212, and the waveguide 213 have shapes extending in the second direction.

[0053] The ultrasonic generator 210 can introduce ultrasonic waves into the waveguide 213 over a wide range in the second direction by using transverse waves generated at the first reflecting surface 221 of the ultrasonic focusing section 212 .

[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, 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.

[0055] (1) In the second embodiment, the ultrasonic generating source, the ultrasonic focusing unit, and the waveguide are configured to be continuously arranged in the second direction. In contrast, the ultrasonic generating source may be composed of a plurality of members and be arranged intermittently in the second direction. The ultrasonic focusing unit may be composed of a plurality of members and be arranged intermittently in the second direction. The waveguide may be composed of a plurality of members and be arranged intermittently in the second direction.

[0056] (2) The cross-sectional shape of the ultrasonic generators of the above embodiments is not limited to the shape shown in Fig. 1. For example, as in ultrasonic generator 310 shown in Fig. 7, the opening width of recess 323 may be configured to increase toward the opening end. Also, as in ultrasonic generator 410 shown in Fig. 8, the cross-sectional shape may have no recess.

[0057] (3) The ultrasonic wave generators of the above embodiments can also be used as receivers that receive reflected waves that are incident on the tip of the waveguide.

[0058] (4) In each of the above embodiments, the ultrasonic wave generating source, the first reflecting surface, and the second reflecting surface are configured to be provided on both sides of the first direction, but they may also be configured to be provided on only one side of the first direction.

[0059] (5) In each of the above embodiments, the transverse waves reflected by the second reflecting surface may not converge at a focal point. Even if a focal point is formed, all of the transverse waves may not converge at the same focal point.

[0060] 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, and is intended to include all modifications within the scope indicated by the claims or within the scope equivalent to the claims.

[0061] DESCRIPTION OF SYMBOLS 10...ultrasonic wave generator 11...ultrasonic wave generating source 11A...one-side generating section 11B...other-side generating section 12...ultrasonic wave focusing section 12A...hole portion 13...waveguide 21...first reflecting surface 21A...first one-side reflecting surface 21B...first other-side reflecting surface 22...second reflecting surface 22A...second one-side reflecting surface 22B...second other-side reflecting surface 23...recess 25A...reflection point 25B...reflection point 27A...reflection point 27B...reflection point 210...ultrasonic wave generator 211...ultrasonic wave generating source 212...ultrasonic wave focusing section 213...waveguide 221...first reflecting surface 310...ultrasonic wave generator 410...ultrasonic wave generator θ1...angle of incidence of longitudinal wave incident on first reflecting surface θ2...reflection angle of shear wave generated at first reflecting surface θ3: Incident angle of the transverse wave incident on the second reflecting surface θ4: Reflection angle of the transverse wave reflected by the second reflecting surface C: Axis F1: First focal point F2: Second focal point P: Power supply

Claims

1. An ultrasonic generator comprising: an ultrasonic generating source that generates ultrasonic waves; an ultrasonic focusing unit that focuses the ultrasonic waves generated by the ultrasonic generating source; and a waveguide that transmits the ultrasonic waves focused by the ultrasonic focusing unit, wherein the ultrasonic focusing unit has a first reflecting surface that reflects the ultrasonic waves generated by the ultrasonic generating source; and a second reflecting surface that reflects the ultrasonic waves reflected by the first reflecting surface, wherein the ultrasonic generating source generates the ultrasonic waves in the form of longitudinal waves; the ultrasonic generator is configured so that the ultrasonic waves in the form of longitudinal waves generated by the ultrasonic generating source are converted into shear waves when reflected by the first reflecting surface and proceed to a first focal point; the second reflecting surface is located on a path along which the ultrasonic waves converted into shear waves at the first reflecting surface proceed to the first focal point; and the ultrasonic generator is configured so that the ultrasonic waves converted into shear waves at the first reflecting surface are reflected as shear waves at the second reflecting surface and introduced into the waveguide.

2. The ultrasonic generating source has a one-side generating unit arranged on one side of the waveguide and a other-side generating unit arranged on the other side of the waveguide in a first direction orthogonal to the direction in which the ultrasonic generating source generates the ultrasonic waves, the first reflecting surface has a first one-side reflecting surface arranged on one side of the waveguide and a first other-side reflecting surface arranged on the other side of the waveguide in the first direction, the second reflecting surface has a second one-side reflecting surface arranged on one side of the waveguide and a second other-side reflecting surface arranged on the other side of the waveguide in the first direction, the one-side generating unit generates the ultrasonic waves of longitudinal waves, the ultrasonic generator is configured so that the ultrasonic waves of longitudinal waves generated from the one-side generating unit are converted into transverse waves when reflected by the first one-side reflecting surface and head towards the first focal point, and the second one-side reflecting surface is located on a path along which the ultrasonic waves converted into transverse waves by the first one-side reflecting surface head towards the first focal point, 2. The ultrasonic generator according to claim 1, wherein the ultrasonic wave generator is configured such that the ultrasonic wave converted into a shear wave at the first one-side reflecting surface is reflected as a shear wave at the second one-side reflecting surface and introduced into the waveguide; the other-side generating unit generates the ultrasonic wave in a longitudinal wave; the ultrasonic generator is configured such that the ultrasonic wave in a longitudinal wave generated from the other-side generating unit is converted into a shear wave when reflected at the first other-side reflecting surface and directed toward the first focal point; the second other-side reflecting surface is located on a path along which the ultrasonic wave converted into a shear wave at the first other-side reflecting surface is directed toward the first focal point; and the ultrasonic generator is configured such that the ultrasonic wave converted into a shear wave at the first other-side reflecting surface is reflected as a shear wave at the second other-side reflecting surface and introduced into the waveguide.

3. The ultrasonic generator according to claim 1 or claim 2, wherein the ultrasonic wave is converted into a shear wave at the first reflecting surface, and is reflected as a shear wave at the second reflecting surface, directed toward the second focal point, and introduced into the waveguide.

4. The ultrasonic generator according to claim 3, wherein the second focal point is located between the base end of the waveguide and the second reflecting surface.

5. An ultrasonic generator as described in claim 1 or claim 2, wherein the second reflecting surface includes a reflection point at which the energy retention rate when the ultrasonic waves converted into transverse waves by the first reflecting surface are reflected as transverse waves is 90% or more.

6. The ultrasonic generator according to claim 5, wherein the Poisson's ratio of the material constituting the second reflecting surface is between 0.17 and 0.34, and the second reflecting surface includes a reflection point at which the angle of incidence of the transverse wave generated by the ultrasonic generating source is between 39.1° and 90°.

7. The ultrasonic generator according to claim 2, wherein the ultrasonic generating source, the ultrasonic focusing section, and the waveguide are shaped to extend in a second direction perpendicular to the first direction among directions perpendicular to the direction in which the ultrasonic generating source generates the ultrasonic waves.

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