JP2024055757A - Ultrasonic generation device - Google Patents

Abstract

To provide an ultrasonic generation device that improves the degree of freedom in changing the overall length and can be made smaller.SOLUTION: An ultrasonic generation device includes a vibrator unit 2 that generates longitudinal vibration, and an ultrasonic radiator 3 that is connected to the transducer unit 2 and that generates ultrasonic waves from longitudinal vibration and radiates them into the air, and the ultrasonic radiator 3 includes a transducer connection portion 4 to which the transducer unit 2 is connected, a conical horn 5 that converts at least a part of the longitudinal vibration transmitted via the vibrator connection portion 4 into transverse vibration, and a flexural diaphragm 6 that is connected to the conical horn 5 and radiates ultrasonic waves by transmitting transverse vibration and flexural vibration.SELECTED DRAWING: Figure 1

Description

The present invention relates to an ultrasonic generator.

For example, Patent Document 1 discloses an ultrasonic sound source. The ultrasonic sound source disclosed in Patent Document 1 includes a transducer, an amplitude magnifying horn, a resonating rod, and a diaphragm. The transducer generates longitudinal vibrations. The longitudinal vibrations generated by the transducer are amplified in amplitude by the amplitude magnifying horn and transmitted to the diaphragm via the resonating rod. The diaphragm vibrates in a bending manner as the longitudinal vibrations are transmitted, and emits ultrasonic waves into the air.

Patent No. 5083970

In the ultrasonic sound source disclosed in Patent Document 1, the vibrator, the amplitude magnification horn, and the resonating rod are each set based on the operating frequency (the frequency of the longitudinal vibration generated by the vibrator) so that they resonate with the longitudinal vibration. For example, the vibrator, the amplitude magnification horn, and the resonating rod are each formed to a length that is half the wavelength of the longitudinal vibration. In this way, the ultrasonic sound source disclosed in Patent Document 1 has a total length that is determined depending on the operating frequency, making it difficult to arbitrarily change the total length. For this reason, it was difficult to shorten the total length and make the ultrasonic sound source disclosed in Patent Document 1 compact.

The present invention was made in consideration of the above-mentioned problems, and aims to provide an ultrasonic generator that improves the degree of freedom in changing the overall length and can be made compact.

The present invention adopts the following configuration as a means for solving the above problems.

The first aspect of the present invention is an ultrasonic generator comprising a transducer unit that generates longitudinal vibrations, and an ultrasonic emitter that is connected to the transducer unit and generates ultrasonic waves from the longitudinal vibrations and emits them into the air, the ultrasonic emitter having a transducer connection section to which the transducer unit is connected, a transverse vibration generating section that converts at least a portion of the longitudinal vibrations transmitted through the transducer connection section into transverse vibrations, and a diaphragm that is connected to the transverse vibration generating section and transmits the transverse vibrations and radiates the ultrasonic waves by flexural vibration.

The second aspect of the present invention is the first aspect, in which the lateral vibration generating unit is a horn whose cross-sectional area perpendicular to the direction of travel of the longitudinal vibration decreases with increasing distance from the transducer unit.

The third aspect of the present invention is the second aspect, in which the horn has a first inclined surface and a second inclined surface that face in opposite directions and approach each other as they move away from the transducer unit, and the first inclined surface and the second inclined surface have different inclination angles with respect to the direction of travel of the longitudinal vibration.

The fourth aspect of the present invention is any one of the first to third aspects, in which the ultrasonic emitter has a plurality of the vibration plates.

The fifth aspect of the present invention is the fourth aspect, in which the multiple diaphragms are arranged in positions where standing waves can be formed between them.

The sixth aspect of the present invention employs a configuration according to the fourth or fifth aspect, in which the lateral vibration generating unit is provided for each of the plurality of diaphragms.

The seventh aspect of the present invention is any one of the first to third aspects described above, in which a single lateral vibration generating section and a single diaphragm are provided for a single transducer connection section.

The eighth aspect of the present invention is the seventh aspect, wherein the horizontal vibration generating unit is a horn whose cross-sectional area perpendicular to the direction of travel of the vertical vibration decreases as it moves away from the transducer unit, the horn has a first inclined surface and a second inclined surface that face in opposite directions and approach each other as it moves away from the transducer unit, the first inclined surface and the second inclined surface have different inclination angles with respect to the direction of travel of the vertical vibration, the first inclined surface is located closer to the center position of the transducer connection part in the vibration direction of the horizontal vibration, and the second inclined surface is located farther from the center position, and the inclination angle of the first inclined surface is larger than the inclination angle of the second inclined surface.

The ninth aspect of the present invention is the seventh aspect, wherein the transducer connection part is formed in a rectangular parallelepiped shape having multiple side surfaces, the horizontal vibration generating part is a horn whose cross-sectional area perpendicular to the direction of travel of the vertical vibration decreases with increasing distance from the transducer unit, the horn has a smooth surface that is flush with the side surface of the transducer connection part and an opposite inclined surface that faces the opposite side to the smooth surface, and one side of the diaphragm is flush with the smooth surface.

The present invention includes an ultrasonic emitter connected to a transducer unit. The ultrasonic emitter also has a transverse vibration generating section that converts longitudinal vibration into transverse vibration. Furthermore, the diaphragm flexes and vibrates when transverse vibration is transmitted. Such an ultrasonic emitter can emit ultrasonic waves without resonating with the longitudinal vibration. Therefore, the length dimension (total length) of the ultrasonic emitter in the traveling direction does not need to be set depending on the wavelength of the longitudinal vibration generated by the transducer unit, and can be set arbitrarily. Therefore, the ultrasonic generator of the present invention has an improved degree of freedom in changing the total length, and can be made smaller.

1 is a perspective view of an ultrasonic generating device according to a first embodiment of the present invention. FIG. 1A and 1B are three-view diagrams of an ultrasonic emitter provided in an ultrasonic generating device in a first embodiment of the present invention, where (a) is a view from the y direction, (b) is a view from the x direction, and (c) is a view from the z direction. FIG. 11 is a diagram showing measurement results of admittance characteristics in an ultrasonic generator according to an embodiment of the present invention. 5A and 5B are diagrams showing the measurement results of vibration displacement of a flexural vibration plate in an ultrasonic generator according to an embodiment of the present invention. FIG. 4 is a diagram showing the measurement results of sound pressure between flexural diaphragms in an ultrasonic generator according to an embodiment of the present invention. FIG. 11 is a perspective view of an ultrasonic generating device according to a second embodiment of the present invention. 11A and 11B are three-view diagrams of an ultrasonic emitter provided in an ultrasonic generating device in a second embodiment of the present invention, where (a) is a diagram viewed from the y direction, (b) is a diagram viewed from the x direction, and (c) is a diagram viewed from the z direction. FIG. 11 is a perspective view of an ultrasonic generating device according to a third embodiment of the present invention. 11A and 11B are three-view diagrams of an ultrasonic emitter provided in an ultrasonic generating device in a third embodiment of the present invention, where (a) is a diagram viewed from the y direction, (b) is a diagram viewed from the x direction, and (c) is a diagram viewed from the z direction. FIG. 13 is a perspective view of an ultrasonic generating device according to a fourth embodiment of the present invention. 11A and 11B are three-view diagrams of an ultrasonic emitter provided in an ultrasonic generating device in a fourth embodiment of the present invention, where (a) is a diagram viewed from the y direction, (b) is a diagram viewed from the x direction, and (c) is a diagram viewed from the z direction. FIG. 13 is a perspective view of an ultrasonic generating device according to a fifth embodiment of the present invention. 13A and 13B are three-view diagrams of an ultrasonic emitter provided in an ultrasonic generating device in a fifth embodiment of the present invention, where (a) is a view from the y direction, (b) is a view from the x direction, and (c) is a view from the z direction.

Below, one embodiment of an ultrasonic generating device according to the present invention will be described with reference to the drawings.

First Embodiment
Fig. 1 is a perspective view of an ultrasonic generator 1 according to the present embodiment. The ultrasonic generator 1 according to the present embodiment is an ultrasonic source that emits ultrasonic waves into the air when power is supplied. As shown in Fig. 1, the ultrasonic generator 1 according to the present embodiment includes a transducer unit 2 and an ultrasonic emitter 3.

The installation position of the ultrasonic generator 1 of this embodiment is not particularly limited. However, in the following description, for convenience, the arrangement direction of the transducer unit 2 and the ultrasonic emitter 3 is defined as the y direction as shown in FIG. 1. The first direction perpendicular to the y direction is defined as the x direction, and the direction perpendicular to the y direction and the x direction is defined as the z direction. The z direction is the direction in which the two flexural vibration plates 6 of the ultrasonic emitter 3, which will be described later, are arranged.

The transducer unit 2 is a unit that generates vibrations (ultrasonic vibrations) and includes multiple piezoelectric elements 2a and a holder 2b. The transducer unit 2 is generally formed in a generally cylindrical shape having an axis L. The transducer unit 2 is arranged so that the axis L is parallel to the y direction.

The multiple piezoelectric elements 2a are stacked in the y direction. When power is supplied to each piezoelectric element 2a, it vibrates with the y direction as the amplitude direction. In other words, when power is supplied to these piezoelectric elements 2a, they generate longitudinal vibrations that travel in the y direction (direction along the axis L). Note that instead of the piezoelectric elements 2a, it is also possible to use electromechanical conversion elements such as magnetostrictive elements and electrostrictive elements. The holder 2b holds the multiple piezoelectric elements 2a between them on both sides in the y direction.

As such a transducer unit 2, for example, a bolt-clamped Langevin type transducer (BLT) that generates strong ultrasonic vibrations can be suitably used. Such a transducer unit 2 is driven by power supplied from a power supply circuit (power supply) not shown.

For example, the overall length of the transducer unit 2 (length dimension in the y direction) is set to half the wavelength of the longitudinal vibration generated by the piezoelectric element 2a. By setting the overall length of the transducer unit 2 in this manner, the transducer unit 2 can be made to resonate with the longitudinal vibration.

The ultrasonic emitter 3 is connected to the transducer unit 2 in the y direction. That is, as described above, the transducer unit 2 and the ultrasonic emitter 3 are arranged in the y direction. This ultrasonic emitter 3 is a part that generates ultrasonic waves from the longitudinal vibration transmitted from the transducer unit 2 and emits them into the air. The ultrasonic emitter 3 is made of, for example, aluminum, aluminum alloy (e.g., duralumin), titanium, titanium alloy, stainless steel, iron, etc., and multiple parts (transducer connection part 4, conical horn 5, and flexible vibration plate 6) described later are integrally formed. Such an ultrasonic emitter 3 is fixed to the transducer unit 2 by, for example, a set screw.

Figure 2 shows three views of the ultrasonic emitter 3, where (a) is a view from the y direction, (b) is a view from the x direction, and (c) is a view from the z direction. As shown in these figures, in this embodiment, the ultrasonic emitter 3 has a transducer connection part 4, a conical horn 5 (lateral vibration generating part), and a flexible vibration plate 6 (vibration plate).

The transducer connection part 4 is a part that is connected to the transducer unit 2. The transducer connection part 4 is formed in a rectangular parallelepiped shape having a transducer connection surface 4a that faces the transducer unit 2. The transducer connection surface 4a has, for example, a screw hole into which the above-mentioned set screw is screwed.

The transducer connection part 4 also has a conical horn 5 on the side opposite the transducer connection surface 4a. As described above, the transducer connection part 4 and the conical horn 5 are integrally formed. For this reason, the boundary surface between the transducer connection part 4 and the conical horn 5 is not provided so as to be visible. However, for ease of explanation, the surface of the transducer connection part 4 facing the conical horn 5 is referred to as the conical horn installation surface 4b. This conical horn installation surface 4b is a surface parallel to the x-z plane.

The conical horn 5 is formed so as to protrude from the conical horn installation surface 4b of the transducer connection part 4 in the direction opposite to the transducer unit 2. In this embodiment, a conical horn 5 is provided for each deflection diaphragm 6. In this embodiment, two deflection diaphragms are provided, and therefore two conical horns 5 are also provided.

Each conical horn 5 converts a portion of the longitudinal vibration component transmitted from the transducer unit 2 into a transverse vibration. More specifically, each conical horn 5 converts a portion of the longitudinal vibration component into a transverse vibration whose displacement direction (amplitude direction) is the z direction. Furthermore, the cross-sectional area (cross-sectional area in the x-z plane) of each conical horn 5 perpendicular to the direction of travel of the longitudinal vibration (y direction) decreases as it moves away from the transducer unit 2. Such a conical horn 5 amplifies the amplitude of the longitudinal vibration and the transverse vibration.

The shape of each conical horn 5 will be described in more detail. As shown in FIG. 2, each conical horn 5 has four side faces, and is formed so that each of the shapes when viewed from the z direction and the shape when viewed from the x direction is a trapezoid. In this embodiment, the two conical horns 5 are formed symmetrically with the x-y plane including the axis L of the transducer unit 2 as the symmetry plane. Of the four side faces, the face facing the other conical horn 5 is referred to as the first face 5a, the face opposite the first face 5a is referred to as the second face 5b, and the remaining two faces are referred to as the third face 5c and the fourth face 5d.

As shown in FIG. 2B, the first surface 5a (first inclined surface) and the second surface 5b (second inclined surface) face in opposite directions and are inclined so as to approach each other as they move away from the vibrator unit 2. The inclination angle α1 of the first surface 5a with respect to the y direction (the direction of longitudinal vibration) is larger than the inclination angle α2 of the second surface 5b with respect to the y direction. That is, in this embodiment, the first surface 5a and the second surface 5b have different inclination angles with respect to the y direction. Therefore, the length dimension from the conical horn installation surface 4b of the first surface 5a to the flexural vibration plate 6 is larger than the length dimension from the conical horn installation surface 4b of the second surface 5b to the flexural vibration plate 6. The inclination angle α1 of the first surface 5a with respect to the y direction (the direction of longitudinal vibration) may be smaller than the inclination angle α2 of the second surface 5b with respect to the y direction.

The first surface 5a and the second surface 5b reflect the longitudinal vibrations traveling inside the conical horn 5. When the longitudinal vibrations are reflected by the first surface 5a or the second surface 5b, a vibration component (lateral vibration component) with the z direction as the displacement direction is generated. Here, because the first surface 5a and the second surface 5b have different inclination angles with respect to the direction of travel of the longitudinal vibration, a difference occurs in the strength of the lateral vibration component generated by the first surface 5a and the lateral vibration component generated by the second surface 5b, and as a result, the conical horn 5 vibrates in the z direction. In other words, lateral vibrations in the z direction are generated in the conical horn 5.

As shown in FIG. 2(c), the third surface 5c and the fourth surface 5d face in opposite directions and are inclined so as to approach each other as they move away from the transducer unit 2. The inclination angle α3 of the third surface 5c with respect to the y direction (the direction of longitudinal vibration) is the same as the inclination angle α4 of the fourth surface 5d with respect to the y direction. In other words, in this embodiment, the third surface 5c and the fourth surface 5d have the same inclination angle with respect to the y direction. Therefore, the length dimension from the conical horn mounting surface 4b of the third surface 5c to the flexural vibration plate 6 is the same as the length dimension from the conical horn mounting surface 4b of the fourth surface 5d to the flexural vibration plate 6.

The third surface 5c and the fourth surface 5d reflect the longitudinal vibrations propagating inside the conical horn 5. When the longitudinal vibrations are reflected by the third surface 5c or the fourth surface 5d, a vibration component with the x-direction as the displacement direction is generated. Because the third surface 5c and the fourth surface 5d have the same inclination angle with respect to the direction of travel of the longitudinal vibration, the vibration components in the x-direction cancel each other out, suppressing the vibration of the conical horn 5 in the x-direction.

In this manner, in this embodiment, each conical horn 5 converts a portion of the longitudinal vibration transmitted from the transducer unit 2 into a transverse vibration with the z direction as the displacement direction (amplitude direction). Such transverse vibration is transmitted to the flexural diaphragm 6 connected to each conical horn 5. Note that, although this embodiment uses a conical horn 5 whose cross-sectional area in the x-z cross section changes at a constant rate in the y direction, an exponential horn whose cross-sectional area in the x-z cross section changes exponentially in the y direction may also be used.

Two flexural diaphragms 6 are provided, one connected to the tip of each conical horn 5 (the end opposite the transducer connection part 4). Each flexural diaphragm 6 is a flat plate-like part with the front and back sides facing in the z direction. The two flexural diaphragms 6 are arranged at a distance in the z direction.

Each flexural diaphragm 6 flexibly vibrates in the z direction as the displacement direction (amplitude direction) due to the lateral vibration transmitted from the conical horn 5. When each flexural diaphragm 6 flexibly vibrates, sound waves are emitted from the flexural diaphragm 6 into the air. In this embodiment, the longitudinal vibration generated by the transducer unit 2 is ultrasonic vibration, and ultrasonic waves are emitted from the flexural diaphragm 6 into the air.

These flexural vibration plates 6 are positioned so that a standing wave can be formed between them. The distance at which a standing wave is formed between the two flexural vibration plates 6 is determined based on the frequency of the ultrasonic waves emitted by the flexural vibration plates 6. The frequency of the ultrasonic waves emitted by the flexural vibration plates 6 is determined based on the frequency of the longitudinal vibration generated by the transducer unit 2. In other words, the separation distance between the flexural vibration plates 6 is set based on the frequency of the longitudinal vibration generated by the transducer unit 2.

As described above, in the ultrasonic emitter 3, the conical horn 5 and the flexural vibration plate 6 are integrated. Such an ultrasonic emitter 3 is connected to the transducer unit 2 and generates ultrasonic waves from the longitudinal vibration and emits them into the air. The total length (length dimension in the y direction) of the ultrasonic emitter 3 does not need to be set depending on the wavelength of the longitudinal vibration and can be set arbitrarily. However, the total length of the ultrasonic emitter 3 may be half the wavelength of the longitudinal vibration.

In the ultrasonic generator 1 of this embodiment, the transducer unit 2 is powered, and the transducer unit 2 generates a longitudinal vibration that travels in the y direction. The longitudinal vibration generated by the transducer unit 2 is transmitted to the ultrasonic emitter 3. The longitudinal vibration transmitted to the ultrasonic emitter 3 is transmitted to each conical horn 5 via the transducer connection part 4. The longitudinal vibration transmitted to each conical horn 5 is reflected in the z direction by the first surface 5a of the conical horn 5. As a result, the conical horn 5 vibrates laterally. In other words, the conical horn 5 converts the longitudinal vibration into a transverse vibration. The transverse vibration generated by the conical horn 5 is transmitted to the flexural vibration plate 6. As the transverse vibration is transmitted to each flexural vibration plate 6, each flexural vibration plate 6 flexibly vibrates, and ultrasonic waves are emitted into the air. In addition, a standing wave is formed between the two flexural vibration plates 6, and ultrasonic waves with a large sound pressure are efficiently emitted.

The ultrasonic generator 1 of this embodiment as described above includes a transducer unit 2 and an ultrasonic emitter 3. The transducer unit 2 generates longitudinal vibrations. The ultrasonic emitter 3 is connected to the transducer unit 2 and generates ultrasonic waves from the longitudinal vibrations and emits them into the air. The ultrasonic emitter 3 also includes a transducer connection part 4, a conical horn 5, and a flexural vibration plate 6. The transducer unit 2 is connected to the transducer connection part 4. The conical horn 5 converts at least a portion of the longitudinal vibrations transmitted via the transducer connection part 4 into lateral vibrations. The flexural vibration plate 6 is connected to the conical horn 5 and emits ultrasonic waves by flexural vibrations transmitted by the lateral vibrations.

As described above, the ultrasonic generator 1 of this embodiment includes an ultrasonic emitter 3 connected to the transducer unit 2. The ultrasonic emitter 3 also has a conical horn 5 that converts vertical vibration into horizontal vibration. Furthermore, the flexural vibration plate 6 flexibly vibrates when the horizontal vibration is transmitted. Such an ultrasonic emitter 3 can emit ultrasonic waves without resonating with the vertical vibration. Therefore, the length dimension (total length) of the ultrasonic emitter 3 in the traveling direction does not need to be set depending on the wavelength of the vertical vibration generated by the transducer unit 2, and can be set arbitrarily. Therefore, the ultrasonic generator 1 of this embodiment has an improved degree of freedom in changing the total length, and can be made smaller.

In addition, in the ultrasonic generator 1 of this embodiment, the conical horn 5 is a horn whose cross-sectional area perpendicular to the direction of travel of the longitudinal vibration decreases as it moves away from the transducer unit 2. Therefore, the conical horn 5 generates transverse vibrations and can increase the amplitude of the vibrations to be transmitted to the flexural diaphragm 6.

In addition, the ultrasonic generator 1 of this embodiment has a conical horn 5 having a first surface 5a and a second surface 5b that face in opposite directions and approach each other as they move away from the transducer unit. The first surface 5a and the second surface 5b also have different inclination angles with respect to the traveling direction of the vertical vibration. Therefore, the ultrasonic generator 1 of this embodiment can generate horizontal vibrations using the conical horn 5 with a simple shape.

In addition, in the ultrasonic generator 1 of this embodiment, the ultrasonic emitter 3 has multiple flexural vibration plates 6. According to the ultrasonic generator 1 of this embodiment, ultrasonic waves can be emitted from multiple parts of the ultrasonic emitter 3.

In addition, in the ultrasonic generator 1 of this embodiment, the multiple flexural vibration plates 6 are arranged in positions where standing waves can be formed between them. By forming standing waves between the multiple flexural vibration plates 6, ultrasonic waves with high sound pressure can be efficiently emitted.

In addition, the ultrasonic generator 1 of this embodiment is provided with a conical horn 5 for each of the multiple flexural vibration plates 6. According to the ultrasonic generator 1 of this embodiment, the shape of each conical horn 5 can be changed depending on the position of the flexural vibration plate 6 and the way it vibrates. Therefore, for example, the multiple flexural vibration plates 6 can be easily positioned in a position where standing waves can be formed.

The above describes a preferred embodiment of the present invention with reference to the attached drawings, but it goes without saying that the present invention is not limited to the above embodiment. The shapes and combinations of the components shown in the above embodiment are merely examples, and various modifications can be made based on design requirements, etc., without departing from the spirit of the present invention.

For example, in the above embodiment, a configuration in which two flexural diaphragms 6 are provided has been described. However, the present invention is not limited to this. For example, a configuration in which a single flexural diaphragm 6 is provided may also be adopted. Also, a configuration in which three or more flexural diaphragms 6 are provided may also be adopted.

In the above embodiment, a configuration in which one flexural diaphragm 6 is provided for one conical horn 5 has been described. However, the present invention is not limited to this. For example, it is also possible to adopt a configuration in which multiple flexural diaphragms 6 are provided for one conical horn 5.

In the above embodiment, the conical horn 5 generates lateral vibrations and increases the amplitude. However, it is also possible to adopt a configuration that includes a lateral vibration generating unit that only generates lateral vibrations.

[Example]
Next, an embodiment of the ultrasonic generator 1 will be described. In this embodiment, the ultrasonic generator 1 is designed so that the resonant frequency is 28 kHz. In this embodiment, the total length in the y direction of the transducer unit 2 and the total length in the y direction of the ultrasonic emitter 3 are each set to a half wavelength of the longitudinal vibration. In other words, the total length in the y direction of the ultrasonic generator 1 of this embodiment is one wavelength of the longitudinal vibration.

In this embodiment, a bolt-tightened Langevin-type longitudinal transducer for 28 kHz was used as the transducer unit 2. The transducer unit 2 has a total length of 89 mm in the y direction and a diameter of 40 mm.

The shape of the ultrasonic emitter 3 in this embodiment was determined as follows, based on a numerical simulation using the finite element method. The total length of the ultrasonic emitter 3 in the y direction is 89 mm. The transducer connection part 4 has a length dimension of 40 mm in the x direction, a length dimension of 20 mm in the y direction, and a length dimension of 40 mm in the z direction. Each conical horn 5 has a length dimension of 40 mm in the x direction, a length dimension of 30 mm in the y direction, and a length dimension of 20 mm in the z direction.

Each flexural vibration plate 6 has a width in the x direction of 20 mm, a length in the y direction of 39 mm, and a thickness in the z direction of 4 mm. Each flexural vibration plate 6 is arranged such that, when viewed from the y direction, both ends in the x direction are located 10 mm from both ends of the conical horn 5. The distance between the two flexural vibration plates 6 is 24.6 mm. The distance between the two flexural vibration plates 6 is twice the wavelength (12.3 mm) of the sound wave emitted from the flexural vibration plate 6. The width in the x direction of each flexural vibration plate 6 is set to a dimension that does not create a node of flexural vibration in the x direction. The width in the y direction of each flexural vibration plate 6 is set to a dimension that creates a node of flexural vibration in the y direction.

(Admittance characteristics of ultrasonic generator)
The admittance characteristics of the ultrasonic generator 1 equipped with the transducer unit 2 were measured. An impedance analyzer was used for the measurement. The drive voltage (effective value) of the piezoelectric element 2a was fixed at 1.0 V. FIG. 3 shows the measurement results of the admittance characteristics in this example. In FIG. 3, the horizontal axis indicates the conductance, and the vertical axis indicates the susceptance. The resonant frequency was 28.34 kHz, the conductance at this time was 6.2 mS (impedance about 160 Ω), and the sharpness Q was about 2800.

(Vibration displacement of flexural diaphragm)
In order to know the flexural vibration distribution of the ultrasonic emitter 3, the vibration displacement of the flexural vibration plate 6 was measured. The origin O of the xyz orthogonal coordinate system was set to the tip corner of one of the flexural vibration plates 6 as shown in FIG. 2(a). The measurement range of the vibration displacement was 0 mm to 20 mm in the x direction and 0 mm to 40 mm in the y direction on the x-y plane at the position of 0 mm in the z direction. The measurement of the vibration displacement of the flexural vibration plate 6 was performed with the input power to the transducer unit 2 being 0.10 W and the frequency being constant at 28.34 kHz. FIG. 4 shows the measurement result of the vibration displacement of the flexural vibration plate 6 in this embodiment. In FIG. 4, the horizontal axis indicates the distance in the y direction, and the vertical axis indicates the distance in the x direction. As shown in FIG. 4, it can be seen that the vibration displacement amplitude is almost uniform in the x direction, and there are vibration nodes near 5 mm and 21 mm in the y axis direction, and there is a large vibration antinode near 30 mm.

(Sound pressure between flexural diaphragms)
In order to know the sound pressure between the two flexural vibration plates 6 of the ultrasonic emitter 3, the sound pressure between the flexural vibration plates 6 was measured with a probe microphone (diameter 1 mm). The measurement range was a y-z plane at a constant position of 10 mm in the x direction, 0 mm to 40 mm in the y direction, and 5 mm to 23 mm in the z direction. The sound pressure was measured with a constant input power of 0.10 W to the transducer unit 2 and a constant frequency of 28.33 kHz. FIG. 5 shows the measurement results of the sound pressure between the flexural vibration plates 6 in this embodiment. In FIG. 5, the horizontal axis indicates the distance in the y direction, and the vertical axis indicates the distance in the z direction. As shown in FIG. 5, it can be seen that there are six antinodes of sound pressure in the measured range. Of these, the values of the antinode positions of the sound pressure at three points near the distance in the y direction from 28 mm to 38 mm are large, and the values of the antinode positions of the sound pressure at three points near the distance in the y direction from 12 mm to 16 mm are relatively small. Both are aligned almost in a straight line in the z direction, and the distance from antinode to antinode of the sound pressure in this direction is about 6 mm, which is almost equal to a half wavelength in air at a frequency of 28 kHz. Also, compared with the results of the vibration displacement amplitude shown in Figure 4, it is found that the position where the sound pressure is large almost coincides with the position where the vibration displacement amplitude is large, which is around 30 mm away in the y direction.

In this embodiment, a method for forming a standing wave sound field was examined in a state where the conical horn 5 and the flexural vibration plate 6 are integrated as the ultrasonic emitter 3. As a result, it became clear that a standing wave sound field can be formed in the air even though the total length is 1/2 the wavelength of the longitudinal vibration.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to Figures 6 and 7. Note that in this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

Figure 6 is a perspective view of the ultrasonic generator 1A of this embodiment. Also, Figure 7 is a three-view diagram of the ultrasonic emitter 3 provided in the ultrasonic generator 1A of this embodiment, where (a) is a view from the y direction, (b) is a view from the x direction, and (c) is a view from the z direction.

As shown in Figures 6 and 7, the ultrasonic emitter 3 of the ultrasonic generator 1A of this embodiment has one conical horn 5 and one flexural vibration plate 6, whereas the first embodiment has two of them. In other words, the ultrasonic emitter 3 of this embodiment has a single conical horn 5 and a single flexural vibration plate 6 for a single transducer connection part 4.

The conical horn 5 is provided on one half of the conical horn installation surface 4b of the transducer connection part 4 from the center position 4b1 in the z direction. The conical horn 5 is not provided on the other half of the conical horn installation surface 4b. In other words, in this embodiment, half of the conical horn installation surface 4b is the exposed surface 4c. Note that the ratio of the area where the conical horn 5 is provided to the exposed surface 4c on the conical horn installation surface 4b can be changed. By changing the ratio of the area where the conical horn 5 is provided to the exposed surface 4c on the conical horn installation surface 4b, the inclination angle α1 of the first surface 5a and the inclination angle α2 of the second surface 5b can be changed.

As in the above embodiment, in this embodiment, the inclination angle α1 of the first surface 5a with respect to the y direction is greater than the inclination angle α2 of the second surface 5b with respect to the y direction. Therefore, the length dimension from the conical horn installation surface 4b of the first surface 5a to the flexural diaphragm 6 is greater than the length dimension from the conical horn installation surface 4b of the second surface 5b to the flexural diaphragm 6.

The first surface 5a is connected to the center position 4b1 in the z direction of the transducer connection part 4. The second surface 5b is connected to the end part on the z direction side (the end part on the -z side) of the transducer connection part 4. In other words, as shown in FIG. 7(b), the first surface 5a is located closer to the center position 4b1 of the transducer connection part 4 in the z direction, which is the vibration direction of the lateral vibration, and the second surface 5b is located farther from the center position 4b1.

In the ultrasonic generator 1A of this embodiment, the single flexural vibration plate 6 flexibly vibrates. As a result, ultrasonic waves are emitted from the flexural vibration plate 6 into the air. This ultrasonic generator 1A can also be used to apply ultrasonic vibration to a tool or the like. For example, by connecting a tool to the flexural vibration plate 6, it is possible to ultrasonically vibrate the tool. This ultrasonic generator 1A can also be used as an atomizer that drops droplets onto the flexural vibration plate 6 to atomize the liquid, or as an atomizer that immerses the flexural vibration plate 6 in liquid to atomize the liquid.

In addition, in the ultrasonic generator 1A of this embodiment, the first surface 5a and the second surface 5b have different inclination angles with respect to the traveling direction of the vertical vibration. Furthermore, the first surface 5a is located closer to the center position 4b1 of the transducer connection part 4 in the vibration direction of the horizontal vibration, and the second surface 5b is located farther from the center position 4b1. The inclination angle α1 of the first surface 5a is greater than the inclination angle α2 of the second surface 5b.

In the ultrasonic generator 1A of this embodiment, the position in the z direction of the flexural vibration plate 6 connected to the tip of the conical horn 5 is on the outside of the center position 4b1 compared to when the inclination angle α1 of the first surface 5a is smaller than the inclination angle α2 of the second surface 5b. In the z direction, a larger flexural vibration can be obtained on the outside of the center position 4b1 of the conical horn installation surface 4b. Therefore, the ultrasonic generator 1A of this embodiment can obtain a larger flexural vibration in the flexural vibration plate 6 than when the inclination angle α1 of the first surface 5a is smaller than the inclination angle α2 of the second surface 5b.

Third Embodiment
Next, a third embodiment of the present invention will be described with reference to Figures 8 and 9. In the description of this embodiment, the description of the same parts as those of the first or second embodiment will be omitted or simplified.

Figure 8 is a perspective view of the ultrasonic generator 1B of this embodiment. Also, Figure 9 is a three-view diagram of the ultrasonic emitter 3 provided in the ultrasonic generator 1B of this embodiment, where (a) is a view from the y direction, (b) is a view from the x direction, and (c) is a view from the z direction.

As shown in Figures 8 and 9, the ultrasonic emitter 3 of the ultrasonic generator 1B of this embodiment has one each of the conical horn 5 and the flexural vibration plate 6, whereas the first embodiment has two of them. In other words, the ultrasonic emitter 3 of this embodiment has a single conical horn 5 and a single flexural vibration plate 6 for a single transducer connection part 4, similar to the second embodiment.

In the ultrasonic generator 1B of this embodiment, the conical horn 5 is provided so as to cover the entire surface of the conical horn installation surface 4b of the transducer connection part 4. As in the above embodiment, in this embodiment, the inclination angle α1 of the first surface 5a with respect to the y direction is larger than the inclination angle α2 of the second surface 5b with respect to the y direction. Therefore, the length dimension from the conical horn installation surface 4b of the first surface 5a to the flexural vibration plate 6 is larger than the length dimension from the conical horn installation surface 4b of the second surface 5b to the flexural vibration plate 6. In addition, the first surface 5a is connected to one end (end on the +z side) of the transducer connection part 4 in the z direction. In addition, the second surface 5b is connected to the other end (end on the -z side) of the transducer connection part 4 on the z direction side.

In the ultrasonic generator 1B of this embodiment, the single flexural vibration plate 6 flexurally vibrates. As a result, ultrasonic waves are emitted from the flexural vibration plate 6 into the air. Note that, like the ultrasonic generator 1A of the second embodiment, this ultrasonic generator 1B can also be used to apply ultrasonic vibrations to tools, etc. For example, by connecting a tool to the flexural vibration plate 6, the tool can be ultrasonically vibrated.

Fourth Embodiment
Next, a fourth embodiment of the present invention will be described with reference to Figures 10 and 11. In the description of this embodiment, the description of the same parts as those of the first, second, or third embodiment will be omitted or simplified.

Figure 10 is a perspective view of the ultrasonic generator 1C of this embodiment. Also, Figure 11 is a three-view diagram of the ultrasonic emitter 3 provided in the ultrasonic generator 1C of this embodiment, where (a) is a view from the y direction, (b) is a view from the x direction, and (c) is a view from the z direction.

As shown in Figures 10 and 11, the ultrasonic emitter 3 of the ultrasonic generator 1C of this embodiment has one each of the conical horn 5 and the flexural vibration plate 6, whereas the first embodiment has two of them. In other words, the ultrasonic emitter 3 of this embodiment has a single conical horn 5 and a single flexural vibration plate 6 for a single transducer connection part 4, similar to the second and third embodiments.

In the ultrasonic generator 1C of this embodiment, the conical horn 5 is provided so as to cover the center of the conical horn installation surface 4b of the transducer connection part 4, excluding the end in the z direction. The first surface 5a is connected to the conical horn installation surface 4b closer to the center than one end (end on the +z side) of the transducer connection part 4 in the z direction. The second surface 5b is connected to the conical horn installation surface 4b closer to the center than the end (end on the -z side) of the transducer connection part 4 in the z direction. Therefore, in this embodiment, an exposed surface 4c on which the conical horn 5 is not provided is formed between each end of the conical horn installation surface 4b in the z direction and the conical horn 5.

Also, as in the above embodiment, in this embodiment, the inclination angle α1 of the first surface 5a with respect to the y direction is greater than the inclination angle α2 of the second surface 5b with respect to the y direction. Therefore, the length dimension from the conical horn installation surface 4b of the first surface 5a to the flexural diaphragm 6 is greater than the length dimension from the conical horn installation surface 4b of the second surface 5b to the flexural diaphragm 6.

In the ultrasonic generator 1C of this embodiment, the single flexural vibration plate 6 flexurally vibrates. As a result, ultrasonic waves are emitted from the flexural vibration plate 6 into the air. Note that this ultrasonic generator 1C can also be used to apply ultrasonic vibrations to tools, etc., similar to the ultrasonic generator 1A of the second embodiment and the ultrasonic generator 1B of the third embodiment. For example, by connecting a tool to the flexural vibration plate 6, the tool can be ultrasonically vibrated.

Fifth Embodiment
Next, a fifth embodiment of the present invention will be described with reference to Figures 12 and 13. Note that in this embodiment, the description of the same parts as those in the first embodiment will be omitted or simplified.

Figure 12 is a perspective view of the ultrasonic generator 1D of this embodiment. Also, Figure 13 is a three-view diagram of the ultrasonic emitter 3 provided in the ultrasonic generator 1D of this embodiment, where (a) is a view from the y direction, (b) is a view from the x direction, and (c) is a view from the z direction.

As shown in Figures 12 and 13, the ultrasonic emitter 3 of the ultrasonic generator 1D of this embodiment has one each of the conical horn 5 and the flexural vibration plate 6, which are provided in pairs in the first embodiment. In other words, the ultrasonic emitter 3 of this embodiment has a single conical horn 5 and a single flexural vibration plate 6 for a single transducer connection part 4.

The conical horn 5 is provided on one half of the conical horn installation surface 4b of the transducer connection part 4 from the center position 4b1 in the z direction. The conical horn 5 is not provided on the other half of the conical horn installation surface 4b. In other words, in this embodiment, half of the conical horn installation surface 4b is the exposed surface 4c. Note that the ratio of the area where the conical horn 5 is provided to the exposed surface 4c on the conical horn installation surface 4b can be changed. By changing the ratio of the area where the conical horn 5 is provided to the exposed surface 4c on the conical horn installation surface 4b, the inclination angle α1 of the first surface 5a and the inclination angle α2 of the second surface 5b can be changed.

In this embodiment, the inclination angle α1 of the first surface 5a with respect to the y direction is greater than 0°. On the other hand, the inclination of the second surface 5b with respect to the y direction is 0°, and the second surface 5b is located in the same plane as one side surface 4d of the transducer connection part 4. In other words, in this embodiment, the second surface 5b is a smooth surface that is flush with one side surface 4d of the transducer connection part 4 formed in a rectangular parallelepiped shape having multiple side surfaces 4d. In addition, one side surface 6a of the flexural diaphragm 6 is flush with the second surface 5b. In other words, in this embodiment, one side surface 4d of the transducer connection part 4, the second surface 5b of the conical horn 5, and one side surface 6a of the flexural diaphragm 6 are located in the same plane.

The length dimension from the conical horn installation surface 4b on the first surface 5a to the flexural vibration plate 6 is greater than the length dimension from the conical horn installation surface 4b on the second surface 5b to the flexural vibration plate 6. The first surface 5a is connected to the center position 4b1 in the z direction of the transducer connection part 4. In other words, the first surface 5a is located closer to the center position 4b1 of the transducer connection part 4 in the z direction, which is the vibration direction of the lateral vibration, and the second surface 5b is located farther from the center position 4b1.

In the ultrasonic generator 1D of this embodiment, a single flexural vibration plate 6 flexurally vibrates. As a result, ultrasonic waves are emitted from the flexural vibration plate 6 into the air. Note that, like the ultrasonic generator 1A of the second embodiment, this ultrasonic generator 1D can also be used to apply ultrasonic vibrations to tools, etc. For example, by connecting a tool to the flexural vibration plate 6, the tool can be ultrasonically vibrated.

In the ultrasonic generator 1D of this embodiment, the conical horn 5 has a second surface 5b, which is a smooth surface that is flush with the side surface 4d of the transducer connection part 4, and a first surface 5a, which is an inclined surface facing the opposite side to the smooth surface. Also, one surface 6a of the flexural vibration plate 6 is flush with the smooth surface. Therefore, the z-direction position of the flexural vibration plate 6 connected to the tip of the conical horn 5 is on the outside with respect to the center position 4b1, compared to the case where the second surface 5b is inclined so that the end of the second surface 5b on the flexural vibration plate 6 side faces the first surface 5a side. In the z direction, a larger flexural vibration can be obtained on the outside with respect to the center position 4b1 of the conical horn installation surface 4b. Therefore, the ultrasonic generator 1D of this embodiment can obtain a large flexural vibration in the flexural vibration plate 6.

In addition, in the ultrasonic generator 1D of this embodiment, one side 4d of the transducer connection part 4, the second surface 5b of the conical horn 5, and one surface 6a of the flexural vibration plate 6 are located in the same plane. Therefore, when forming the ultrasonic emitter 3 by a method such as cutting, one side 4d of the transducer connection part 4, the second surface 5b of the conical horn 5, and one surface 6a of the flexural vibration plate 6 can be formed in a planar shape, making it easy to form.

1: Ultrasonic generator, 1A-1D: Ultrasonic generator, 2: Transducer unit, 3: Ultrasonic emitter, 4: Transducer connection part, 4a: Transducer connection surface, 4b: Conical horn installation surface, 4c: Exposed surface, 4d: Side surface, 5: Conical horn (horizontal vibration generating part, horn), 5a: First surface (first inclined surface), 5b: Second surface (second inclined surface), 5c: Third surface, 5d: Fourth surface, 6: Flexural vibration plate (vibration plate)

Claims (9)

A transducer unit that generates longitudinal vibrations;
an ultrasonic emitter connected to the transducer unit, which generates ultrasonic waves from the longitudinal vibration and emits the ultrasonic waves into the air;
The ultrasonic emitter is
a transducer connection portion to which the transducer unit is connected;
a lateral vibration generating unit that converts at least a part of the longitudinal vibration transmitted through the transducer connection unit into a lateral vibration;
a vibration plate connected to the lateral vibration generating unit, the vibration plate flexurally vibrating when the lateral vibration is transmitted thereto, thereby radiating the ultrasonic waves. The ultrasonic generator according to claim 1, characterized in that the lateral vibration generating unit is a horn whose cross-sectional area perpendicular to the direction of travel of the longitudinal vibration decreases with increasing distance from the transducer unit. The horn is
a first inclined surface and a second inclined surface that face in opposite directions and approach each other as they move away from the transducer unit;
3. The ultrasonic generating device according to claim 2, wherein the first inclined surface and the second inclined surface have different inclination angles with respect to the traveling direction of the longitudinal vibration. An ultrasonic generator according to any one of claims 1 to 3, characterized in that the ultrasonic emitter has a plurality of the vibration plates. The ultrasonic generator according to claim 4, characterized in that the vibration plates are arranged in positions where standing waves can be formed between them. The ultrasonic generator according to claim 4, characterized in that the lateral vibration generating unit is provided for each of the multiple vibration plates. An ultrasonic generator according to any one of claims 1 to 3, characterized in that a single transverse vibration generating unit and a single vibration plate are provided for a single transducer connection unit. the transverse vibration generating unit is a horn having a cross-sectional area perpendicular to a direction in which the longitudinal vibration propagates, the cross-sectional area decreasing with increasing distance from the transducer unit;
The horn is
a first inclined surface and a second inclined surface that face in opposite directions and approach each other as they move away from the transducer unit;
the first inclined surface and the second inclined surface have different inclination angles with respect to a traveling direction of the longitudinal vibration,
8. The ultrasonic generator according to claim 7, wherein the first inclined surface is located closer to a center position of the transducer connection portion in the vibration direction of the lateral vibration, the second inclined surface is located farther from the center position, and the inclination angle of the first inclined surface is larger than the inclination angle of the second inclined surface. The transducer connection portion is formed in a rectangular parallelepiped shape having a plurality of side surfaces,
the transverse vibration generating unit is a horn having a cross-sectional area perpendicular to a direction in which the longitudinal vibration propagates, the cross-sectional area decreasing with increasing distance from the transducer unit;
the horn has a smooth surface that is flush with the side surface of the transducer connection portion and an opposite inclined surface that faces the opposite side to the smooth surface,
8. The ultrasonic generator according to claim 7, wherein one surface of the vibration plate is flush with the smooth surface.

Images