Ultrasonic supply device

Abstract

The purpose of the present invention is to provide an ultrasound supply device which can acquire information about the periphery of a ultrasound output unit. This ultrasound supply device 100 is provided with: a first reflective member which has a first reflective surface 11a which is arranged coaxially with a circular ultrasound radiation surface SR and which reflects and focuses the ultrasound SW from the ultrasound radiation surface SR; a second reflective member 12 which is arranged coaxially with the ultrasound radiation surface SR and which has a second reflective surface 12a which reflects forwards and collimates the ultrasound SW reflected by the first reflective surface 11a; and a double cylinder-shape member which comprises an outer tube 13a that extends forwards from the center of the first reflective member 11, an inner tube 13b which extends forwards from the center of the second reflective member 12, and an annular tip part 13d that connects the outer tube 13a and the inner tube 13b at the front tip. The first reflective member 11, the outer tube 13a, the annular tip part 13d, the inner tube 13b and the second reflective member 12 form an acoustic space S1 which is separated away from the axial space S2 inside of the inner tube 13b and which is solid or hollow.

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic supply device for locally supplying ultrasonic waves, and more particularly to an ultrasonic supply device having a thin rod that emits ultrasonic waves from its tip. [Background technology]

[0002] A known ultrasonic supply device includes a circular piezoelectric ceramic vibration element, a first paraboloid for focusing that reflects ultrasonic waves from the piezoelectric ceramic vibration element, and a second paraboloid for collimating that reflects ultrasonic waves from the first paraboloid, and sends plane waves to a thin rod extending forward from the central region of the first paraboloid (Non-Patent Document 1).

[0003] Although the ultrasonic supply device can output ultrasonic waves from the tip of the thin rod, it is not easy to obtain information about the area around the tip of the thin rod. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] K. Chen, et al., "Double-parabolic-reflectors acoustic waveguides for high-power medical ultrasound," Sci. Rep., vol. 9, 18493, 2019. Summary of the Invention

[0005] The present invention has been made in view of the above-mentioned background art, and has as its object to provide an ultrasonic supply device capable of acquiring information about the surroundings of an ultrasonic output unit.

[0006] An ultrasonic supply device for solving the above problems includes a first reflecting member that is arranged coaxially with an annular ultrasonic emitting surface and has a first reflecting surface that reflects and focuses ultrasonic waves from the ultrasonic emitting surface, a second reflecting member that is arranged coaxially with the ultrasonic emitting surface and has a second reflecting surface that reflects and collimates the ultrasonic waves reflected by the first reflecting surface forward, an outer tube extending forward from the center of the first reflecting member, an inner tube extending forward from the center of the second reflecting member, and a double cylindrical member that has an annular tip portion that connects the outer tube and inner tube at their front tips, and an acoustic space separated from the axial space in the inner tube is formed by the first reflecting member, the outer tube, the annular tip portion, the inner tube, and the second reflecting member.

[0007] In the ultrasonic delivery device, the first reflecting member, the outer cylinder, the annular tip portion, the inner cylinder, and the second reflecting member form an acoustic space separated from the axial space in the inner cylinder, so that ultrasonic waves from the ultrasonic emitting surface can be sent into the double cylindrical member in a collimated state or in a state equivalent thereto through the acoustic space, and powerful ultrasonic waves can be irradiated onto a target from the tip of the double cylindrical member. Furthermore, by incorporating various sensors in the axial space in the inner cylinder, it is possible not only to obtain information about the area around the tip of the double cylindrical member, but also to deliver medicines or other substances to the area around the tip of the double cylindrical member, and to aspirate and collect substances present around the tip of the double cylindrical member.

[0008] In a specific embodiment, the first reflecting surface has a shape formed by rotating a forward convex curve. The first reflecting member receives and reflects ultrasonic waves from the ultrasonic wave emitting surface with a concave surface, thereby focusing the ultrasonic waves.

[0009] In a specific embodiment, the second reflecting surface has a shape formed by rotating a concave or convex curve forward.

[0010] In a specific embodiment, the first reflecting member focuses ultrasonic waves from the ultrasonic emitting surface into an annular region, and the second reflecting member transmits ultrasonic waves from the annular region into an acoustic space extending between the outer tube and the inner tube.

[0011] In a specific embodiment, the first reflecting surface is a rotationally symmetric surface obtained by rotating a parabola extending outward in an axial cross section of the outer cylinder around the central axis of the outer cylinder, which allows ultrasonic waves from the ultrasonic emitting surface to be efficiently focused into an annular region.

[0012] In a specific embodiment, the second reflecting surface is a rotationally symmetric surface formed by rotating an inwardly extending parabola, the focal point of which coincides with an outwardly extending parabola in an axial cross section of the outer cylinder, around the central axis of the outer cylinder. In this case, ultrasonic waves without phase shift directed toward the double cylindrical member can be efficiently formed.

[0013] In a specific embodiment, the ultrasonic supply device further includes an annular base end member disposed in front of the ultrasonic wave emitting surface and connecting the outer edge of the first reflecting member and the outer edge of the second reflecting member to form a closed acoustic space. In this case, a closed acoustic space is formed by the ultrasonic vibration device consisting of the first reflecting member, the outer cylinder, the annular tip plate portion, the inner cylinder, the second reflecting member, and the base end member, and the acoustic characteristics of the ultrasonic supply device can be stabilized.

[0014] In a specific embodiment, the base end member has a cylindrical portion connected at its tip to the outer edge of the first reflecting member, and an annular portion connected at its outer periphery to the base end of the cylindrical portion and connected at its inner periphery to the outer edge of the second reflecting member, which makes it easy to ensure a relatively wide second reflecting surface.

[0015] In a specific embodiment, the base member is connected at its outer edge to the outer edge of the first reflecting member and at its inner edge to the outer edge of the second reflecting member.

[0016] In particular aspects, the acoustic space is solid or hollow.

[0017] In a specific embodiment, the ultrasonic supply device further includes an ultrasonic source that emits ultrasonic waves forward from the annular ultrasonic wave emitting surface. By incorporating the ultrasonic source, ultrasonic waves of a desired intensity can be irradiated onto a target from the tip of the double cylindrical member.

[0018] In a specific embodiment, the ultrasonic source is a piezoelectric element having electrodes formed on the front and rear surfaces of a circular plate-shaped piezoelectric ceramic.

[0019] In a specific embodiment, the ultrasonic source is fixed to an annular base member disposed between the outer edges of the first reflecting member and the second reflecting member by an adhesive that is cured, compressed, and annealed.

[0020] In a specific embodiment, the device further includes a sensor inserted into the axial space of the inner cylinder to acquire information about the area around the tip of the inner cylinder, where the sensor includes various devices that detect sound pressure, temperature, images, etc.

[0021] In a specific embodiment, the ratio of the diameter of the double cylindrical member to the diameter of the first reflecting member is 1:2 or less. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 2 is a cross-sectional view of the ultrasonic supply device of the first embodiment. [Figure 2] FIG. 1 is a conceptual perspective view illustrating ultrasound waves emitted from the tip of a hollow thin rod. [Figure 3] 10A and 10B are cross-sectional views illustrating an application example of an ultrasonic supply device. [Figure 4] FIG. 10 is a cross-sectional view illustrating an ultrasonic supply device of a comparative example. [Figure 5] FIG. 10 is a cross-sectional view illustrating an ultrasonic supply device according to a second embodiment. [Figure 6] 6A to 6C show frequency characteristics of admittance and vibration velocity when the tip of the thin rod of the ultrasonic vibration device is in contact with air or water. [Figure 7] 7A to 7C show the simulation results of the maximum sound pressure distribution during burst driving. [Figure 8] The results of a simulation of the underwater sound pressure distribution on the central axis of the ultrasonic vibration device are shown below. [Figure 9]The results of a simulation of the energy flow rate from the tip of a thin rod of an ultrasonic vibration device are shown below. [Figure 10] FIG. 10 is a conceptual cross-sectional view illustrating a director of a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0023] [First embodiment] Hereinafter, a first embodiment of an ultrasonic supply device according to the present invention will be described with reference to the drawings.

[0024] 1, an ultrasonic supply device 100 of the first embodiment includes an ultrasonic vibration device 10 and a drive device 20. The ultrasonic vibration device 10 includes a waveguide 10a that outputs ultrasonic waves SW from a tip portion 10t, and an ultrasonic source 10b that supplies ultrasonic waves SW to the waveguide 10a. The waveguide 10a has an outer shape similar to a funnel, and includes a disk-shaped base portion 10i and a thin rod 10j with a hollow axis.

[0025] Of the ultrasonic vibration device 10, the director 10a is formed of a metal material such as duralumin, and includes a first reflecting member 11, a second reflecting member 12, a double cylindrical member 13, a base end member 14, and a flange 15. The first reflecting member 11, the second reflecting member 12, the base end member 14, etc. form the base 10i in appearance, and the double cylindrical member 13 forms the thin rod 10j.

[0026] The first reflecting member 11 is formed of a thin plate or surface obtained by cutting out a portion of a dome into an annular shape, and has a first reflecting surface 11a that is arranged coaxially with the annular ultrasound emitting surface SR and reflects ultrasound SW from the ultrasound emitting surface SR and focuses it toward the annular region RA. The second reflecting member 12 is formed of a thin plate or surface obtained by cutting out a portion of a toroidal surface or a hyperboloid of one sheet into an annular shape, and has a second reflecting surface 12a that is arranged coaxially with the ultrasound emitting surface SR and reflects and collimates the ultrasound SW reflected by the first reflecting surface 11a forward. The double cylindrical member 13 has an outer cylinder 13a extending forward from the center of the first reflecting member 11, an inner cylinder 13b extending forward from the center of the second reflecting member 12, and an annular tip portion 13d that connects the outer cylinder 13a and inner cylinder 13b at their front tips. The base end member 14 is disposed near the front of the ultrasonic wave emitting surface SR, and connects the outer edge 11e of the first reflecting member 11 and the outer edge 12e of the second reflecting member 12 to form the acoustic space S1 into a closed space. The flange 15 is provided to fix the ultrasonic vibration device 10 to a support or stage (not shown).

[0027] The inner cylinder 13b of the double cylindrical member 13 is penetrated and has an axial space S2 which is a hollow space corresponding to the through-hole 13c. The axial space S2 and the acoustic space S1 surrounded by the first reflecting member 11 and the second reflecting member 12 are separated by the inner cylinder 13b, and the axial space S2 and the acoustic space S1 are isolated or separated from each other.

[0028] Base end member 14 has a cylindrical portion 14a connected at its tip to outer edge 11e of first reflecting member 11, and an annular portion 14b connected at its outer periphery to the base end of cylindrical portion 14a and connected at its inner periphery to outer edge 12e of second reflecting member 12. In this case, it is easy to ensure a relatively wide second reflecting surface.

[0029] The first reflecting member 11 and the outer cylinder 13a can be formed as an integrated member, but this is not a limitation and they can be formed separately and then joined. The second reflecting member 12 and the inner cylinder 13b can also be formed as an integrated member, but this is not a limitation and they can be formed separately and then joined. Furthermore, they can be formed as an integrated member, including the annular tip portion 13d. Methods such as welding and adhesive bonding can be used to join the first reflecting member 11, the second reflecting member 12, etc. The acoustic space S1 formed by the first reflecting member 11, the outer cylinder 13a, the annular tip portion 13d, the inner cylinder 13b, the second reflecting member 12, and the base end member 14 is hollow, but can be filled with various types of gases and liquids.

[0030] The acoustic space S1 may be solid. In this case, the acoustic space S1 is filled with the same material as, for example, the first reflecting member 11, the outer cylinder 13a, the annular tip portion 13d, the inner cylinder 13b, the second reflecting member 12, and the base end member 14. However, the acoustic space S1 may be filled with a different material from the first reflecting member 11. Whether the acoustic space S1 is solid or hollow, it serves as a medium for uniformly propagating sound waves. When the first reflecting member 11, the outer cylinder 13a, the annular tip portion 13d, the inner cylinder 13b, the second reflecting member 12, and the base end member 14 are made of the same material and the acoustic space S1 is also filled with the same material and is solid, the waveguide 10a is an integrated part formed from a single material. In this case, the surface layer of such an integrated product constitutes the first reflecting member 11, the second reflecting member 12, the outer tube 13a, the inner tube 13b, etc., and specific areas of the surface of such an integrated product function as the first reflecting surface 11a, the second reflecting surface 12a, etc.

[0031] The first reflecting surface 11a of the first reflecting member 11 focuses the ultrasonic waves SW from the ultrasonic emitting surface SR onto an annular region RA corresponding to the focal point. For this reason, the first reflecting surface 11a has a shape obtained by rotating a curve that is convex forward, i.e., in the +Y direction. The second reflecting surface 12a of the second reflecting member 12 transmits the ultrasonic waves SW that pass through the annular region RA and diverge into the space S12 formed between the outer tube 13a and the inner tube 13b. For this reason, the second reflecting surface 12a has a shape obtained by rotating a curve that is concave forward, i.e., in the +Y direction. The ultrasonic waves SW transmitted into the space S12 are similar to plane waves, and their phases are approximately aligned in the Y direction, which is the direction of propagation.

[0032] The first reflecting surface 11a of the first reflecting member 11 is a rotationally symmetric surface obtained by rotating a forward-convex parabola (outer parabola) extending outside the reference cylindrical surface IT around the central axis AX of the outer barrel 13a, with the generatrix of the reference cylindrical surface IT being the axis of symmetry TX in the axial cross section (specifically, the XY plane) of the outer barrel 13a. The second reflecting surface 12a of the second reflecting member 12 is a rotationally symmetric surface obtained by rotating a forward-concave parabola (inner parabola) extending inside the reference cylindrical surface IT around the central axis AX of the outer barrel 13a, with the generatrix of the reference cylindrical surface IT being the axis of symmetry TX in the axial cross section (specifically, the XY plane) of the outer barrel 13a. Here, the focus of the parabola outside the reference cylindrical surface IT and the focus of the parabola inside the reference cylindrical surface IT coincide with each other and are located on an annular region RA. Rotationally symmetric surfaces such as the first reflecting surface 11a and the second reflecting surface 12a are also called parabolic surfaces of revolution. The reference cylindrical surface IT does not need to coincide with the outer cylinder 13a, and may be larger or smaller than the outer cylinder 13a. In other words, the annular area RA corresponding to the focus of the first reflecting surface 11a may be located inside or outside the cylindrical surface extending from the outer cylinder 13a.

[0033] The ratio of the diameter of the thin rod 10j or the double cylindrical member 13 to the diameter of the base 10i or the diameter of the first reflecting member 11 should not exceed 1:2. If the diameter of the thin rod 10j is relatively large, the propagation loss of the ultrasonic waves increases. For example, if the outer diameter of the base 10i or the ultrasonic source 10b is 40 mm, the outer diameter of the thin rod 10j should be at most about 20 mm.

[0034] The flange 15 for fixing the ultrasonic vibration device 10 to a support or stage may be integral with the main body including the first reflecting member 11 and the base end member 14, or may be made separately from the main body and then joined. When vibration of the outer circumferential side surface of the double cylindrical member 13 is small, the ultrasonic vibration device 10 can also be fixed to the support via the outer periphery of the double cylindrical member 13. When supporting the ultrasonic vibration device 10, the periphery of the base 10i consisting of the first reflecting member 11 and the second reflecting member 12 can be housed in a ground-shielded cover.

[0035] The ultrasonic source 10b is a thick, annular member that emits plane-wave ultrasonic waves SW forward from its front, annular ultrasonic radiation surface SR. The ultrasonic waves SW pass through the annular portion 14b of the base end member 14, are guided into the acoustic space S1, and are incident on the first reflecting surface 11a of the first reflecting member 11. The ultrasonic source 10b is a piezoelectric element having electrodes 32 and 33 formed on the front and rear surfaces of an annular plate-shaped piezoelectric ceramic 31. The piezoelectric ceramic 31 has discrete resonant frequency characteristics determined by its overall structure, which enable the output of powerful ultrasonic waves SW, and resonant frequency characteristics determined by the thickness of the piezoelectric ceramic 31. The thinner the thickness of the piezoelectric ceramic 31, the higher the fundamental frequency can be. The ultrasonic source 10b is bonded to the annular portion 14b of the base end member 14 using, for example, an adhesive. If the ultrasonic source 10b is detachable, the ultrasonic source 10b can be replaced.

[0036] When bonding the ultrasonic source 10b to the annular portion 14b, an adhesive is applied to the surface of the annular portion 14b at the base 10i, the ultrasonic source 10b is pressed against it to harden, and then the ultrasonic source 10b is annealed in an oven while being pre-compressed against the annular portion 14b. For example, epoxy resin is used as the adhesive, and the thickness when hardening the adhesive is set to 2 to 50 μm, the pre-compression range is 4 to 80 kPa, and the annealing temperature is 100 to 200°C. The material and composition of the adhesive can be changed in various ways.

[0037] The driving device 20 includes a power supply circuit 21 that supplies a sine wave driving signal of, for example, several tens of kHz to several MHz to the ultrasonic source 10b, and a control circuit 22 that controls the operating state of the power supply circuit 21.

[0038] The operation of the ultrasonic supply device 100 of this embodiment will be described. The power supply circuit 21 is operated under the control of the control circuit 22, causing the ultrasonic source 10b to emit plane-wave ultrasonic waves SW forward from the ultrasonic radiation surface SR. The ultrasonic waves SW pass through the annular portion 14b of the base end member 14, enter the acoustic space S1, and then enter the first reflecting surface 11a of the first reflecting member 11. The ultrasonic waves SW are reflected by the first reflecting surface 11a and converge onto an annular region RA corresponding to the focal point. The ultrasonic waves SW that have passed through the annular region RA enter the second reflecting surface 12a of the second reflecting member 12. The ultrasonic waves SW are reflected by the second reflecting surface 12a and emitted with high energy density into the narrow space S12 formed between the outer tube 13a and the inner tube 13b. The ultrasonic waves SW collected in the space S12 are guided while remaining close to a plane wave, pass through the annular tip portion 13d, and are emitted forward of the thin rod 10j with high energy density (see FIG. 2). Specifically, when a powerful ultrasonic wave is irradiated onto the liquid filling the front of the annular tip portion 13d and the through-hole 13c of the thin rod 10j is filled with liquid, the ultrasonic wave propagates into the liquid in the through-hole 13c as it propagates through the tubular waveguide, and a powerful ultrasonic wave SW2 is also irradiated onto the liquid filling the front of the through-hole 13c. Note that the ultrasonic wave SW emitted in front of the thin rod 10j is not limited to the ultrasonic wave SW of the frequency inherent to the ultrasonic source 10b, and it is also possible to radiate an ultrasonic wave SW of a resonant mode of 1 / odd fraction of the length of the thin rod 10j due to the resonance of the thin rod 10j. Such an ultrasonic wave SW can be a relatively low frequency, such as an odd multiple of several tens of kHz.

[0039] FIG. 3 shows an application example of the ultrasonic supply device 100 shown in FIG. 1 and other figures. In this case, a measuring device 51 is inserted into the through-hole 13c of the thin rod 10j to measure the condition around the tip of the thin rod 10j. The measuring device 51 has a sensor 53 attached to the tip of a cable 52 and operates under the control of the driving device 20. The sensor 53 can be a sound pressure sensor that detects sound pressure, enabling the measurement of echoes, etc. The thin rod 10j can be made long and thin, and can be inserted into the inside of a human organ using, for example, a surgical technique (specifically, a small incision). In other words, the inside of a human organ can be observed with minimal damage, and by increasing the intensity of the ultrasound SW, harmful tissue such as cancerous tissue can be destroyed.

[0040] The sensor 53 is not limited to a sound pressure sensor, but can be replaced with a temperature sensor, a camera, a substance sensor, etc. Although not shown, the through-hole 13c can be used to deliver a drug to a target site around the tip of the thin rod 10j, and can also be used to aspirate or collect tissue or other samples from the target site.

[0041] Applications of the ultrasonic dispenser 100 include not only those that apply ultrasonic waves to the tip of the thin rod 10j, but also atomization devices. By supplying water, alcohol, or a solution containing a drug mixed with various solvents to the base of the through-hole 13c of the thin rod 10j in FIG. 3, the water, solution, etc. passing through the through-hole 13c is atomized, and a mist containing the water or drug solution is ejected from the tip of the thin rod 10j. In this case, the inner surface of the through-hole 13c, i.e., the inner tube 13b, applies ultrasonic vibrations to the water or various solutions from the surroundings while also applying ultrasonic vibrations along the path through the through-hole 13c. This significantly increases the atomization efficiency and reduces the size of the particles that make up the mist. Such atomization is expected to be accompanied by a pumping effect. The pumping effect is a phenomenon in which the presence of surface waves (Rayleigh waves, Lamb waves, etc.) causes the liquid or its particles on the surface to move under the force of the waves. In the ultrasonic dispenser 100, the solution or droplets introduced into the thin rod 10j are thought to move due to the ultrasonic vibrations. Although the direction of movement has not been confirmed in principle, it has been confirmed that a droplet of solution moves toward the tip of the thin rod 10j, assuming that a surface wave is formed on the inner surface of the through-hole 13 of the thin rod 10j toward the tip or the +Y direction.

[0042] In the ultrasonic supply device 100, the higher the frequency of the ultrasonic waves supplied to the base 10i, the more vibrations can be concentrated on the inner surface. Therefore, when the ultrasonic vibration device 10 is used as an atomization device, the higher the ultrasonic frequency, the higher the atomization efficiency. Furthermore, the greater the difference between the outer diameter and the inner diameter of the thin rod 10j, the more vibrations can be concentrated inside, thereby improving atomization efficiency. By setting the ultrasonic frequency to 1 MHz or higher, the efficiency of vibration application to water or solution can be improved, and particle size can be reduced. Specifically, when water is supplied from the base side of the through-hole 13c of the thin rod 10j, it is desirable to generate ultrasonic waves with a frequency of 1.85 MHz using the ultrasonic source 10b, taking into account the resonance peak.

[0043] In the ultrasonic supply device 100 of the first embodiment described above, an acoustic space S1 separated from the axial space S2 in the inner cylinder 13b is formed by the first reflecting member 11, the outer cylinder 13a, the annular tip portion 13d, the inner cylinder 13b, and the second reflecting member 12, so that the ultrasonic waves SW from the ultrasonic emitting surface SR can be sent into the double cylindrical member 13 (i.e., space S12) in a substantially collimated state via the acoustic space S1, and powerful ultrasonic waves SW can be irradiated onto a target from the tip portion 10t of the double cylindrical member 13. Furthermore, by incorporating various sensors in the axial space S2 in the inner cylinder 13b, it is possible not only to acquire information about the area around the tips of the double cylindrical member 13, but also to deliver medicines or other substances to the area around the tips of the double cylindrical member 13, and to aspirate and collect substances present around the tips of the double cylindrical member 13.

[0044] FIG. 4 shows a comparative example of a director 910a, which is a modification of the director 10a shown in FIG. 1. In the comparative example of the director 910a, the second reflecting surface 12a of the second reflecting member 12 is arranged rotationally symmetrically around the central axis AX, and the inner edge closest to the central axis AX is recessed most toward the acoustic space S1. In the case of the comparative example of the director 910a, the ultrasonic waves SW reflected by the first reflecting surface 11a of the first reflecting member 11 are blocked by the inner cylinder 13b and are therefore less likely to be incident on the second reflecting surface 12a. As a result, it becomes difficult to send powerful ultrasonic waves SW into the space S12 of the double cylindrical member 13, and it also becomes difficult to irradiate powerful ultrasonic waves SW from the tip end 10t of the thin rod 10j.

[0045] Second Embodiment An ultrasonic supply device according to a second embodiment of the present invention will be described below. The ultrasonic supply device of the second embodiment is a partial modification of the ultrasonic supply device of the first embodiment, and a description of the common parts will be omitted.

[0046] FIG. 5 is a diagram illustrating a waveguide 210a incorporated in an ultrasonic supply device 100 according to a second embodiment. Hereinafter, the waveguide 210a shown in FIG. 5 will be referred to as the second type, and the waveguide 10a shown in FIG. 1 will be referred to as the first type. The second type of waveguide 210a has a smaller radius of the annular region RA. The base end member 14 is annular, connected at its outer periphery to the outer edge 11e of the first reflecting member 11, and connected at its inner edge to the outer edge 12e of the second reflecting member 12. The second reflecting member 12 is provided with a second reflecting surface 12a that is concave forward and radially outward. The second reflecting member 12 is provided with a connecting surface 12j that is concave radially inward and forward and that is connected to the inner edge of the base end member 14, radially outward of the second reflecting surface 12a. In other words, the second reflecting member 12 forms an annular groove in the acoustic space S1 and appears to protrude annularly from the surface of the base end member 14.

[0047] In the second type of director 210a, the acoustic space S1 is, for example, hollow, but it may be solid and filled with the same material as the first reflecting member 11, etc., or it may be filled with a material different from the first reflecting member 11, etc.

[0048] In the second type director 210a shown in Figure 5, the second reflecting surface 12a is formed in a recess in the acoustic space S1 and has a small area, so it is thought that the output of the ultrasonic wave SW will be weaker than that of the first type director 10a shown in Figure 1.

[0049] [Experiments and Simulations] 6A to 6C show frequency characteristics of admittance and vibration velocity when the tip of the thin rod 10j of the ultrasonic vibration device 10 is in contact with air or water. FIG. 6A shows the admittance, velocity, etc. of an ultrasonic vibration device 10 equipped with a first-type director 10a (hereinafter also referred to as Type 1 ultrasonic vibration device 10), FIG. 6B shows the admittance, etc. of an ultrasonic vibration device 10 equipped with a second-type director 210a (hereinafter also referred to as Type 2 ultrasonic vibration device 10), and FIG. 6C shows the admittance, etc. of an ultrasonic vibration device of a comparative example. In the above, the directors 10a, 210a, and 910a of the ultrasonic vibration devices are assumed to be solid and made of duralumin. The admittance of the ultrasonic vibration device is determined from the state of power supply to the ultrasonic source 10b, and the velocity is obtained by measuring the tip 10t of the thin rod 10j with a laser vibrometer. The radius of the outer edge 11e of the first reflecting member 11 was 20 mm, the radius of the outer edge 12e of the second reflecting member 12 was 3 mm, the length of the outer tube 13a was 10 mm, the radius of the outer tube 13a was 2.5 mm, and the radius of the inner tube 13b was 1.0 mm. The piezoelectric ceramic 31 of the ultrasonic source 10b was a circular PZT with an inner diameter of 16 mm or 18 mm, an outer diameter of 40 mm, and a thickness of 1.1 mm. As is clear from the change in admittance, both ultrasonic vibration devices exhibited numerous resonance peaks in a wide frequency range from 1.5 to 2.0 MHz. While nearly identical resonance peaks were observed when the tip was in contact with air and when it was in contact with water, there were some areas where the amplitude was slightly larger when the tip was in contact with air. Furthermore, in the ultrasonic vibration device 10 shown in FIGS. 6A and 6B, a large vibration velocity peak is obtained in the band of 1.5 to 2.0 MHz, which is close to the resonance frequency of the piezoelectric ceramic 31, 1.74 MHz.

[0050] Figures 7A to 7C show simulation results of maximum sound pressure distribution during instantaneous burst driving for the directors 10a, 210a, and 910a described in Figures 6A to 6C. Figure 7A shows the results for an ultrasonic vibration device 10 equipped with a first-type director 10a (Type 1 ultrasonic vibration device 10), Figure 7B shows the results for an ultrasonic vibration device 10 equipped with a second-type director 210a (Type 2 ultrasonic vibration device 10), and Figure 7C shows the results for a comparative ultrasonic vibration device. For burst driving, a voltage of 100 Vpp was applied to the ultrasonic source 10b, a frequency of 1.7 MHz, and a five-cycle sine wave was used. In the case of the Type 1 ultrasonic vibration device 10, a high sound pressure of approximately 1.0 MPa was obtained at the focal point, demonstrating the effectiveness of the principle of focusing sound waves using reflections from two parabolic surfaces of revolution. It was also found that when driven at a frequency around 1.7 MHz, the vibration amplitude near the inner circumference of the waveguide tip became significantly larger.

[0051] Figure 8 shows the results of a simulation of the underwater sound pressure distribution along the central axis of a solid director, assuming that the tip of the thin rod 10j is in contact with water. The voltage applied to the ultrasonic source 10b was 100 Vpp, the frequency was 1.7 MHz, and a 5-cycle sine wave was used. The simulation targets the above-mentioned Type 1 ultrasonic vibration device 10, Type 2 ultrasonic vibration device 10, and the ultrasonic vibration device of the comparative example. In the case of the ultrasonic vibration device 10 equipped with the Type 1 director 10a, a maximum underwater sound pressure of 3.1 MPa was generated 2.6 mm from the tip, which was 1.6 times the maximum sound pressure of the ultrasonic vibration device of the comparative example.

[0052] Figure 9 shows the results of a simulation of the energy flow rate from the tip of the thin rod 10j for a solid waveguide, assuming that the tip of the thin rod 10j is in contact with water. The voltage applied to the ultrasonic source 10b was 100 Vpp, the frequency was 1.7 MHz, and a 5-cycle sine wave was used. The simulation targets the Type 1 ultrasonic vibration device 10, the Type 2 ultrasonic vibration device 10, and the comparative ultrasonic vibration device. The "core" indicates the energy propagating from the central axial space S2 through which the central axis of the thin rod 10j passes, and the "shell" indicates the energy propagating from the annular tip portion 13d, which is the tip of the outer portion of the thin rod 10j. Comparing the energy flow from the outer portions, the Type 1 ultrasonic vibration device 10 was found to have the largest energy flow rate, followed by the Type 2 ultrasonic vibration device 10. In other words, it was found that the focusing principle due to its shape works well in the Type 1 ultrasonic vibration device 10, and that it exhibits higher performance in terms of generated sound pressure and output energy than the Type 2 ultrasonic vibration device 10 and the comparative ultrasonic vibration device.

[0053] As a result of additional simulations, we confirmed that, in solid waveguide 10a, with respect to the vibration of the waveguide inner wall near axial space S2, which is the deep portion of through-hole 13c, ultrasonic vibrations can be concentrated approximately 5 mm from the inner wall, i.e., on inner tube 13b forming the inner surface of through-hole 13c. In waveguide 10a having a structure similar to that of the above simulation, we found that, as a condition for concentrating ultrasonic vibrations on the inner surface of through-hole 13c of thin rod 10j, the wall thickness (= (outer diameter - inner diameter) / 2) of thin rod 10j is preferably 5 mm or more for a frequency of 1.7 MHz, and the wall thickness of thin rod 10j is preferably 2.5 mm or more for a frequency of 3.4 MHz. In other words, the product of the frequency applied to thin rod 10j and the lower limit of the preferable outer diameter of thin rod 10j is a constant, and this constant is affected by the shape of waveguide 10a (particularly the range of incident angles of ultrasonic waves SW on first reflecting surface 11a) and the material of waveguide 10a (mainly the Poisson's ratio of the material).

[0054] In addition, as a result of additional simulations, it was found that longitudinal waves and transverse waves are generated by the reflection of the ultrasonic waves SW at the reflecting surface 11a, and that due to the subsequent branching of the paths, the ultrasonic waves output from the tip of the thin rod 10j contain a pair of peaks that reach the annular tip portion 13d of the waveguide with a short time difference.

[0055] The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the present invention.

[0056] For example, the double cylindrical member 13 is not limited to one having a constant diameter, but may have a tapered or divergent shape, and the same applies to the outer cylinder 13a and the inner cylinder 13b.

[0057] The annular tip portion 13d is not limited to a flat surface, but may also be a tapered surface. That is, the annular tip portion 13d may have a shape such that the side surface of a cone is cut out by two planes parallel to the axis of the cone.

[0058] The first reflecting surface 11a and the second reflecting surface 12a do not necessarily have strict geometric shapes. In other words, the first reflecting surface 11a is not limited to a shape obtained by rotating a parabola around the central axis AX, but may have a shape obtained by rotating a curve convex toward the front, i.e., the +Y side, and specifically includes a spherical surface, a free-form surface, or the like, as long as it focuses plane-wave ultrasonic waves. Furthermore, the second reflecting surface 12a is not limited to a shape obtained by rotating a parabola around the central axis AX, but may have a shape obtained by rotating a curve concave toward the front, i.e., the +Y side, and specifically includes a spherical surface, a free-form surface, or the like, as long as it focuses diverging ultrasonic waves into plane waves.

[0059] FIG. 10 shows a modified example of the director 10a shown in FIG. 1. In this case, a second reflecting surface 12a that is convex toward the front of the second reflecting member 12, i.e., the +Y side, is provided. The ultrasonic waves SW reflected by the first reflecting surface 11a of the first reflecting member 11 are incident on the second reflecting surface 12a while being focused, but are reflected by the second reflecting surface 12a and collimated before reaching the focal point. In this case, the first reflecting surface 11a and the second reflecting surface 12a are both parabolic, arranged concentrically, and have the same focal point. In the illustrated director 10a, the acoustic space S1 is, for example, hollow, but may be solid and filled with the same material as the first reflecting member 11, etc., or may be filled with a material different from the first reflecting member 11, etc.

[0060] Director 10a is not limited to being made of an aluminum alloy such as duralumin, but may be made of a titanium alloy or the like.

[0061] The ultrasonic source 10b can be one that operates on various principles, and is not limited to one that uses the piezoelectric ceramic 31. The piezoelectric ceramic 31 is not limited to a single ring, and may be one that is divided into multiple pieces.

Claims

1. a first reflecting member having a first reflecting surface that is arranged coaxially with the annular ultrasonic wave emitting surface and that reflects and focuses the ultrasonic waves from the ultrasonic wave emitting surface; a second reflecting member having a second reflecting surface arranged coaxially with the ultrasonic wave emitting surface and configured to reflect and collimate the ultrasonic waves reflected by the first reflecting surface forward; a double cylindrical member having an outer cylinder extending forward from the center of the first reflecting member, an inner cylinder extending forward from the center of the second reflecting member, and an annular tip portion connecting the outer cylinder and the inner cylinder at a front tip, An ultrasonic supply device, wherein the first reflecting member, the outer cylinder, the annular tip portion, the inner cylinder, and the second reflecting member form an acoustic space separated from an axial space in the inner cylinder.

2. The ultrasonic supply device according to claim 1 , wherein the first reflecting surface has a shape obtained by rotating a forwardly convex curve.

3. The ultrasonic supply device according to claim 2 , wherein the second reflecting surface has a shape obtained by rotating a curve that is concave or convex forward.

4. the first reflecting member focuses the ultrasonic waves from the ultrasonic emitting surface into an annular region; The ultrasonic supply device according to any one of claims 1 to 3, wherein the second reflecting member transmits the ultrasonic waves from the annular region to the acoustic space extending between the outer cylinder and the inner cylinder.

5. 5. The ultrasonic supply device according to claim 4, wherein the first reflecting surface is a rotationally symmetric surface obtained by rotating a parabola extending outward in an axial cross section of the outer cylinder around a central axis of the outer cylinder.

6. 6. The ultrasonic supply device according to claim 5, wherein the second reflecting surface is a rotationally symmetric surface obtained by rotating an inwardly extending parabola, the focus of which is coincident with the outwardly extending parabola in an axial cross section of the outer cylinder, around the central axis of the outer cylinder.

7. The ultrasonic supply device according to any one of claims 1 to 6, further comprising an annular base end member arranged in front of the ultrasonic radiation surface, connecting the outer edge of the first reflecting member and the outer edge of the second reflecting member to make the acoustic space a closed space.

8. The ultrasonic supply device according to any one of claims 1 to 7, wherein the acoustic space is solid.

9. The ultrasonic supply device according to any one of claims 1 to 7, wherein the acoustic space is hollow.

10. The ultrasonic supply device according to any one of claims 1 to 9, further comprising an ultrasonic source that emits ultrasonic waves forward from an annular ultrasonic wave emitting surface.

11. 11. The ultrasonic supply device according to claim 10, wherein the ultrasonic source is a piezoelectric element having electrodes formed on the front and rear surfaces of a circular plate-shaped piezoelectric ceramic.

12. 12. The ultrasonic supply device of claim 10, wherein the ultrasonic source is fixed to an annular base member disposed between an outer edge of the first reflecting member and an outer edge of the second reflecting member by an adhesive that is annealed while being compressed and preloaded after hardening.

13. The ultrasonic supply device according to any one of claims 1 to 12, further comprising a sensor inserted into an axial space of the inner cylinder to obtain information around the tip of the inner cylinder.

14. 14. The ultrasonic delivery device of claim 1, wherein a ratio of a diameter of the double cylindrical member to a diameter of the first reflecting member is 1:2 or less.

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