WO2009096347A1

WO2009096347A1 - Ultrasonic wave generating device, and apparatus having the device

Info

Publication number: WO2009096347A1
Application number: PCT/JP2009/051153
Authority: WO
Inventors: Susumu Fujiwara; Sota Komae
Original assignee: Mitsubishi Electric Corporation
Priority date: 2008-01-31
Filing date: 2009-01-26
Publication date: 2009-08-06
Also published as: JPWO2009096347A1

Abstract

Provided are an ultrasonic generating device, which can emit ultrasonic waves of a high sound pressure level (especially of 140 dB or higher) over a wide range, and an apparatus equipped with the ultrasonic generating device. The ultrasonic generating device (100) is characterized by comprising a diaphragm (10) (an ultrasonic vibrator) having a piezoelectric element (10a), and a diaphragm (12) mounted at the tip of the diaphragm (10), for resonating with the vibrations of the diaphragm (10) so that it performs the 'flexural oscillations' to generate ultrasonic waves.

Description

Ultrasonic generator and equipment equipped with the same

The present invention relates to an ultrasonic generator that generates ultrasonic waves, and more particularly to an ultrasonic generator that can radiate ultrasonic waves having a strong sound pressure level over a wide range and equipment equipped with the ultrasonic generator.

Conventionally, there are ultrasonic generators using piezoelectric elements such as PZT (lead zirconate titanate). In general, such an ultrasonic generator oscillates a piezoelectric element by applying a voltage to the piezoelectric element, and oscillates a specific frequency by using a resonance frequency of vibration in a certain direction. It has become. Therefore, the sound pressure level depends on the input voltage for driving the piezoelectric element. Further, the frequency generated by the piezoelectric element generally has an ultrasonic range of 18 kHz or higher, which is different from the frequency of the audible range, and the sound pressure level is extremely attenuated when radiated in the air. Become.

In order to amplify the sound pressure level, a resonance structure (horn structure) is attached to the surface vibration direction of the piezoelectric element, and means for matching the frequency of the surface vibration of the piezoelectric element with the frequency of the resonance structure is provided. Generally done. As such, “a transducer unit that generates ultrasonic vibrations and a horn that amplifies the vibrations of the transducer unit and the combined length of the transducer unit and the horn are It is an ultrasonic generator that is approximately ½, and a plurality of horns are attached in parallel to the transducer part, and the output side of each horn is connected by a resonance plate ” Has been proposed (see, for example, Patent Document 1).

Also disclosed is a technique in which sound radiation is combined as a means for promoting electrostatic dust collection by corona discharge. As such, “comprising a charging part, a dust collecting part, and a sound wave generating means for irradiating a sound wave to at least a part of the discharge part of the charging part, wherein the charging part is opposed to the discharge electrode. An electrostatic precipitator that radiates sound waves to at least a discharge space between the discharge electrode and the counter electrode has been proposed (see, for example, Patent Document 2). ). This electric dust collector is adapted to enhance dust collection such as dust by corona discharge by adding application of sound radiation.

Japanese Patent Laid-Open No. 2001-70881 (page 3, FIG. 1) Japanese Patent No. 3700685 (5th page, Fig. 2)

In the ultrasonic generator described in Patent Document 1, the sound pressure level amplified by the horn structure remains the same as the ultrasonic wave, and the directivity sharpness that is the original characteristic of the ultrasonic wave is not changed. The sound emission to the front surface of the ultrasonic element with a very narrow angle is generated strongly, and when it radiates in the air, it will be extremely attenuated. Therefore, there is a problem that ultrasonic waves having a strong sound pressure level cannot be radiated over a wide range, and such a request cannot be met.

In the electrostatic precipitator described in Patent Document 2, since corona discharge is the main component and the sound pressure level of the device that emits sound is unknown, there is a problem that improvement in dust collection efficiency due to sound emission cannot be expected. Yes. Moreover, in the actual product form, one aerial ultrasonic element is mounted. However, the aerial ultrasonic element does not generate a sound pressure level that increases the dust collection efficiency, and does not collect dust. I found out that there was no. Therefore, in addition to the problem that ultrasonic waves having a strong sound pressure level cannot be radiated in a wide range, there is a problem that the dust collection effect is low.

The present invention has been made to solve the above-described problems, and an ultrasonic generator capable of radiating an ultrasonic wave having a strong sound pressure level (especially 140 dB or more) over a wide range and an equipment having the same Equipment is provided.

An ultrasonic generator according to the present invention is flexibly vibrated by resonating with an ultrasonic vibrator provided with a piezoelectric element, and attached to a tip portion of the ultrasonic vibrator and resonating with the vibration of the ultrasonic vibrator. And a diaphragm that generates ultrasonic waves. Moreover, the equipment according to the present invention includes the above-described ultrasonic generator and a housing on which the ultrasonic generator is mounted.

According to the ultrasonic generator according to the present invention, since the diaphragm that “bends and vibrates” is provided, ultrasonic waves having a strong sound pressure level can be radiated in a wide range. Moreover, since the equipment according to the present invention includes the ultrasonic generator having such an effect, it has the same effect.

FIG. 3 is an explanatory diagram for explaining an example of an ultrasonic generator according to the first embodiment. FIG. 6 is an explanatory diagram for explaining another example of the ultrasonic generator according to the first embodiment. It is explanatory drawing for demonstrating the ultrasonic radiation in the state which installed the reflective diaphragm. It is explanatory drawing for demonstrating the ultrasonic radiation in the state which installed the several reflection diaphragm. It is description for demonstrating the ultrasonic radiation in the state which installed the diaphragm (including a reflective diaphragm) which has a curved surface shape. It is explanatory drawing for demonstrating the state which bent the terminal part of the vibrator | oscillator by the predetermined angle. It is a graph which shows the resonance characteristic of an ultrasonic generator. It is a schematic block diagram which shows a part of structure of the air cleaner which concerns on Embodiment 2. FIG.

Explanation of symbols

10 vibrators, 10a piezoelectric elements, 11 horns, 12 diaphragms, 12a diaphragms, 12b diaphragms, 14 fixed members, 15 bending stepped parts, 22 reflective diaphragms, 23 reflective diaphragms, 24 reflective diaphragms, 25 reflective vibrations Plate, 26 reflective diaphragm, 30 dust collecting filter, 31 blower fan, 100 ultrasonic generator, 100a ultrasonic generator, 200 air cleaner.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is an explanatory diagram for explaining an example of the ultrasonic generator 100 according to Embodiment 1 of the present invention. Based on FIG. 1, the configuration of the ultrasonic generator 100 and “flexural vibration” that is a characteristic item of the ultrasonic generator 100 will be described. FIG. 1A is a plan view showing the state of the ultrasonic generator 100 viewed from above, and FIG. 1B is a schematic cross-sectional view showing the longitudinal cross-sectional configuration of the ultrasonic generator 100. . In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

The ultrasonic generator 100 applies a pulse voltage to an ultrasonic vibrator composed of a piezoelectric element such as PZT (lead zirconate titanate) and oscillates the vibrator to generate ultrasonic waves. ing. As shown in FIG. 1, the ultrasonic generator 100 includes a vibrator (ultrasonic vibrator) 10, a horn 11, and a diaphragm 12. The vibrator 10 is provided with a piezoelectric element 10a, and is oscillated by applying a pulse voltage via a positive electrode terminal and a negative electrode terminal (not shown). That is, the vibrator 10 has a function of oscillating a sound wave (ultrasonic wave) in a predetermined frequency range (generally around 40 kHz) when a pulse voltage is applied.

The horn 11 is configured such that both end surfaces are opened and an acoustic path (a path for amplifying an ultrasonic band acoustic signal) is formed therein, and is attached between the vibrator 10 and the diaphragm 12. ing. In addition, the horn 11 is preferably formed in a truncated cone shape and is gradually reduced in diameter from the vibrator 10 side toward the diaphragm 12 side. The diaphragm 12 is fixed so as to block the other end of the horn 11 (the end opposite to the one end where the vibrator 10 is disposed) and resonates with the oscillation (vibration) of the vibrator 10. It has a function to generate ultrasonic waves that are resonance waves. The ultrasonic waves are generated from both surfaces of the diaphragm 12 (the surface on the horn 11 side (the surface on which the vibrator 10 is installed when the horn 11 is not provided) and the opposite surface thereof).

Further, the diaphragm 12 is fixed to an “antinode” portion of an ultrasonic signal (oscillation mode wave line A ₁ inside the vibrator 10) transmitted from the vibrator 10. The diaphragm 12 performs “flexural vibration”. That is, the diaphragm 12 vibrates in the “lattice mode” determined by the natural frequency of the plate itself. As shown by a broken line in FIG. 1A, the diaphragm 12 has a grid-like broken line portion as “node (sparse portion in generated ultrasonic wave)” and a portion other than the broken line as “antinode (generated). "Dense part in the ultrasonic wave") is "flexible vibration". In the ultrasonic generator 100, the vibration frequency of the vibration mode of the diaphragm 12 is used so as to coincide with the oscillation frequency of the vibrator 10.

Here, the “flexural vibration” of the “lattice mode” will be described. The diaphragm 12 is fixed to the tip of the horn 11, and an ultrasonic signal (wave line A ₁ ) transmitted from the vibrator 10 and propagated through the horn 11 propagates. Since the vibration frequency of the vibration mode of the diaphragm 12 coincides with the oscillation frequency of the vibrator 10, it is vibrated (resonated) by the propagated ultrasonic signal (dashed line B ₁ ). At this time, when the diaphragm 12 “bends and vibrates”, an ultrasonic wave is generated and radiated to both sides of the diaphragm 12.

The magnitude | size of the diaphragm 12 can be determined by the following calculation formula (1), and a desired dimension can be designed.
λ = {2πCph / f} * 1/2 Formula (1)
Here, λ represents the wavelength, Cp represents the intrinsic constant of the plate material constituting the diaphragm 12, h represents the thickness of the plate material constituting the diaphragm 12, and f represents the frequency. Cp is a constant specific to the material constituting the diaphragm 12, and can be calculated using the Young's modulus, Poisson's ratio, or the like of the material.

Further, the length L ₁ of one side of the diaphragm 12 necessary for generating the “lattice mode” can be determined by the following calculation formula (2).
L ₁ = (N ₁ −0.5) * λ / 2 Formula (2)
Here, N ₁ represents the number (even values) of “node” lines appearing on the diaphragm 12.
That is, if the length L ₁ of one side of the diaphragm 12 is set to the relationship represented by the expression (2), the mode shape at the time of the flexural vibration of the diaphragm 12 can be set to “lattice mode”.

Therefore, by vibrating the diaphragm 12 in the “lattice mode”, the diaphragm 12 can vibrate at a specific frequency equivalent to the ultrasonic signal transmitted from the vibrator 10. Since the frequency of the diaphragm 12 by this specific frequency is radiated from the entire surface of the diaphragm 12, a powerful sound having a frequency in a specific ultrasonic band from a wide area corresponding to the size of the diaphragm 12 is obtained. (140 dB or more) is uniformly emitted in the air (30 cm or more along the central axis of the vibrator 10). Although FIG. 1 shows an example in which the horn 11 is provided, the diaphragm 12 may be fixed to the tip of the vibrator 10.

FIG. 2 is an explanatory diagram for explaining another example of the ultrasonic generator 100a according to Embodiment 1 of the present invention. Based on FIG. 2, the structure of the ultrasonic generator 100a and “flexural vibration” which is a characteristic item of the ultrasonic generator 100a will be described. FIG. 2A is a plan view showing the state of the ultrasonic generator 100a viewed from above, and FIG. 2B is a schematic cross-sectional view showing the longitudinal cross-sectional configuration of the ultrasonic generator 100a. . In FIG. 2, differences from the ultrasonic generator 100 according to FIG. 1 will be mainly described, and the same parts as those of the ultrasonic generator 100 will be denoted by the same reference numerals and description thereof will be omitted. .

The diaphragm 12a is fixed so as to block the other end of the horn 11 (the end opposite to the end where the vibrator 10 is disposed) and resonates with the oscillation (vibration) of the vibrator 10. It has a function to generate ultrasonic waves that are resonance waves. The ultrasonic waves are generated from both surfaces of the diaphragm 12a (the surface on the horn 11 side (surface on the lower side of the paper) and the opposite surface (surface on the upper side of the paper). In addition, the diaphragm 12a is fixed to a portion where an “antinode” of an ultrasonic signal transmitted from the vibrator 10 (oscillation mode inside the vibrator 10: wave line A ₂ ) occurs. The diaphragm 12 a performs “flexural vibration” in the same manner as the diaphragm 12. However, the diaphragm 12a does not vibrate in the “lattice mode” but in the “parallel stripe mode” determined by the natural frequency of the plate itself.

As shown by a broken line in FIG. 2A, the diaphragm 12a has a broken line portion that is a parallel stripe as “node (sparse portion in generated ultrasonic wave)” and a portion other than the broken line as “antinode (generated). "Dense part in the ultrasonic wave") is "flexible vibration". In the ultrasonic generator 100a, the vibration frequency of the vibration mode of the diaphragm 12a is used so as to coincide with the oscillation frequency of the vibrator 10. Incidentally, it is possible to determine the size of the diaphragm 12a by the above formula (1), determines the length L ₂ of one side of the diaphragm 12a necessary for generation of "parallel fringe mode" in the above formula (2) be able to.

Here, “flexural vibration” of the “parallel stripe mode” will be described. The diaphragm 12a is fixed to the tip of the horn 11, and an ultrasonic signal (wave line A ₂ ) transmitted from the vibrator 10 and propagated through the horn 11 propagates. Since the vibration frequency of the vibration mode of the vibration plate 12a coincides with the oscillation frequency of the vibrator 10, it is excited (resonated) by the propagated ultrasonic signal (dashed line B ₂ ). At this time, when the vibration plate 12a “bends and vibrates”, an ultrasonic wave is generated and radiated to both surfaces of the vibration plate 12a.

Therefore, by vibrating the diaphragm 12a in the “parallel stripe mode”, the diaphragm 12a can vibrate at a specific frequency equivalent to the ultrasonic signal transmitted from the vibrator 10. Since the frequency of the diaphragm 12a with this specific frequency is radiated from the entire surface of the diaphragm 12a, a powerful sound having a frequency in a specific ultrasonic band from a wide area corresponding to the size of the diaphragm 12a. (140 dB or more) is uniformly emitted in the air (30 cm or more along the central axis of the vibrator 10). 2 shows an example in which the horn 11 is provided, but the diaphragm 12a may be fixed to the vibrator 10.

FIG. 3 is an explanatory diagram for explaining ultrasonic radiation in a state where the reflection diaphragm 22 is installed. Based on FIG. 3, the radiation of ultrasonic waves in a state where the reflection diaphragm 22 is installed in the ultrasonic generator 100 or the ultrasonic generator 100a will be described. As described above, in the ultrasonic generator 100 and the ultrasonic generator 100a, strong ultrasonic waves are uniformly emitted in the air from both surfaces of the diaphragm 12 and the diaphragm 12a. Therefore, the reflection diaphragm 22 that performs “flexural vibration” is disposed to face the diaphragm 12 at a predetermined interval (distance K calculated by the calculation formula (3) described below), and the diaphragm 12 and the diaphragm 12a. The ultrasonic wave radiated from is not attenuated. The state where the reflection diaphragm 22 is installed in the ultrasonic generator 100 will be described as an example.

That is, sound radiation from the diaphragm 12 (ultrasonic radiation region: on the front surface (surface on the upper side of the paper) and the vicinity sound field of the vibration plate 12, and further on the front and rear surfaces (surface on the lower surface of the paper) of the vibration plate 12. By installing the reflection diaphragm 22 for reflecting the arrow C), sound radiation having a strong sound pressure level is always repeatedly emitted between the reflection diaphragm 22 and the diaphragm 12 to be emitted (arrow D). It has become. At this time, the diaphragm 12 is fixed to the portion where the “antinode” of the ultrasonic signal transmitted from the vibrator 10 is generated as described above, and the reflection diaphragm 22 is “node” of the ultrasonic signal transmitted from the vibrator 10. ”Is fixed to the portion where“

That is, the diaphragm 12 fixed to the tip of the horn 11 (the part where the “antinode” occurs), which is the place where the resonance frequency is the strongest, and the reflective diaphragm 22 fixed to the other part (the part where the “node” occurs) Is used to repeatedly reflect ultrasonic waves between the two. In FIG. 3, a case where the reflection diaphragm 22 is installed on the rear surface of the diaphragm 12 is shown as an example. Therefore, the front surface of the diaphragm 12 is an ultrasonic radiation area, and the area between the diaphragm 12 and the reflection diaphragm 22 is an ultrasonic wave generation area.

As described above, the ultrasonic wave is repeatedly radiated / reflected between the diaphragm 12 and the reflection diaphragm 22, so that the ultrasonic waves having a plurality of sharp directivities are formed between the diaphragm 12 and the reflection diaphragm 22. Signals (arrow C and arrow D) are generated, and it is possible to have a “sound wall” due to ultrasonic waves that repeat dense and dense waves. FIG. 3 shows an example in which the reflection diaphragm 22 is fixed by the fixing member 14. In this case, as long as the fixing member 14 is fixed to the portion where the “node” occurs, the reflection diaphragm 22 may not be fixed to the portion where the “node” occurs.

The predetermined interval between the diaphragm 12 and the reflection diaphragm 22 can be determined by a relationship satisfying the following calculation formula (3).
K = (λs / 2) * N ₂ Formula (3)
Here, K represents a predetermined interval, that is, distance between the diaphragm 12 and the reflection diaphragm 22, λs represents the wavelength of the frequency generated in the diaphragm 12, and N ₂ represents the order (odd value). If the reflection diaphragm 22 is installed with the value of the interval K calculated by the calculation formula (3), the sound radiation (arrow C) from the diaphragm 12 is not attenuated, and the reflection diaphragm 22 and the diaphragm 12 are not attenuated. Can be repeatedly emitted (arrow D).

In other words, in order to have a plurality of “sound walls” by ultrasonic waves having a sharp directivity between the diaphragm 12 and the reflection diaphragm 22, the reflection diaphragm 22 is opposed to the diaphragm 12, and the calculation formula It must be installed at a position that satisfies the interval K calculated in (3). The interval K calculated by the calculation formula (3) corresponds to a portion where the “node (sparse portion in the generated ultrasonic wave)” of the ultrasonic signal transmitted from the vibrator 10 occurs. 22 is fixed to the portion where the “node” occurs. Even when a plurality of reflection diaphragms are installed, the reflection diaphragms may be installed at intervals K.

FIG. 4 is an explanatory diagram for explaining ultrasonic radiation in a state where a plurality of reflection diaphragms are installed. Based on FIG. 4, the radiation of ultrasonic waves in a state where a plurality of reflection diaphragms (reflection diaphragm 23 and reflection diaphragm 24) are installed in the ultrasonic generator 100 and the ultrasonic generator 100a will be described. The state where a reflection diaphragm is installed in the ultrasonic generator 100 will be described as an example. Further, the reflection diaphragm 23 and the reflection diaphragm 24 also vibrate “bend”. Furthermore, the case where the reflection diaphragm 23 installed on the front side of the diaphragm 12 is a case surface of equipment (for example, an air purifier) on which the ultrasonic generator 100 is mounted is shown as an example.

In FIG. 3, the case where one reflection diaphragm 22 is installed has been described as an example. However, the number of the reflection diaphragms 22 is not limited, and two or more reflection diaphragms (the reflection diaphragm 22 and the reflection vibration) are not limited. A plate 23) can also be installed. Also in this case, the reflection diaphragm 22 is fixed to the interval K calculated by the above formula (3), that is, the “sparse” portion of the ultrasonic signal that is the standing / sparse dense wave transmitted from the vibrator 10. There is a need. As shown in FIG. 4, the distance K ₂ between the diaphragm 12 and the reflection diaphragm 24 is three times the distance K ₁ between the diaphragm 12 and the reflection diaphragm 23.

Further, the directivity of the ultrasonic wave generated in the diaphragm 12 is the largest in the central axis direction of the vibrator 10, but a side wave (an arrow C ₁ and an arrow having an arbitrary angle) depending on the vibration mode of the diaphragm 12. C ₂ ) is also generated. Therefore, by making the surface areas of the reflection diaphragm 23 and the reflection diaphragm 24 larger than the surface area of the diaphragm 12, side waves can be effectively used. Further, the surface areas of the reflection diaphragm 23 and the reflection diaphragm 24 may be the same or different. In addition, although the case where the reflective diaphragm 24 is a housing | casing surface is shown as an example, it is not limited to this. FIG. 4 shows an example in which the reflection diaphragm 23 is fixed by the fixing member 14 in the same manner as the reflection diaphragm 22.

FIG. 5 is an explanatory diagram for explaining ultrasonic radiation in a state where a diaphragm having a curved surface (including a reflective diaphragm) is installed. Based on FIG. 5, the radiation of ultrasonic waves in a state where a plurality of diaphragms having curved shapes are installed in the ultrasonic generator 100 or the ultrasonic generator 100a will be described. Note that an example in which a diaphragm having a curved surface (the diaphragm 12b, the reflection diaphragm 25, and the reflection diaphragm 26) is installed in the ultrasonic generator 100 will be described. Further, the diaphragm 12b, the reflection diaphragm 25, and the reflection diaphragm 26 are also "flexed". Furthermore, the case where the reflection diaphragm 26 installed on the front side of the diaphragm 12b is the case surface of the equipment of the equipment on which the ultrasonic generator 100 is mounted is shown as an example.

4 shows a state in which planar diaphragms (diaphragm 12, reflection diaphragm 23, and reflection diaphragm 24) are installed, but in FIG. 5, a diaphragm having a curved surface shape (diaphragm 12b, reflection vibration). The state which installed the board 25 and the reflective diaphragm 26) is shown. Also in this case, if the interval K calculated by the above equation (3), that is, the parallelism between the diaphragms is maintained, a diaphragm having a curved surface (for example, a plurality of similar circular arc shapes as shown in FIG. 5). It is also possible to install a diaphragm. Therefore, it is possible to configure the diaphragm in a shape corresponding to the casing surface of the equipment on which the ultrasonic generator 100 or the ultrasonic generator 100a is mounted.

FIG. 6 is an explanatory diagram for explaining a state in which the end portion of the vibrator 10 is bent at a predetermined angle. Based on FIG. 6, description will be given of ultrasonic radiation in a state where a bending step portion 15 bent at a predetermined angle is formed at the end portion of the vibrator 10 (tip portion on the side where the horn 11 is installed: upper side of the paper). To do. As shown in FIG. 6, the bending step portion 15 is formed in the vibrator 10, and a horn 11 for converging the vibration wave on the end surface (tip portion of the vibrator 10) of the bending step portion 15 is provided. It is attached. A diaphragm 12 (which may be the diaphragm 12a or the diaphragm 12b) is fixed to the tip of the horn 11.

In this way, the ultrasonic generator 100 and the ultrasonic generator 100a can be mounted even in a narrow space. That is, the shape of the vibrator 10 can be made to correspond to the shape and size of the equipment on which the ultrasonic generator 100 and the ultrasonic generator 100a are mounted. Here, the state in which the end portion of the vibrator 10 is bent at a predetermined angle has been described as an example. However, the present invention is not limited to this, and the horn 11 may be bent at a predetermined angle. Further, the number of diaphragms (including the reflective diaphragm) is not limited, and a plurality of diaphragms can be provided as long as the interval K calculated by the calculation formula (3) is satisfied.

FIG. 7 is a graph showing the resonance characteristics of the ultrasonic generator 100. Based on FIG. 7, the resonance characteristics of the ultrasonic generator 100 will be described. The resonance characteristics of the ultrasonic generator 100 will be described as an example, but the same applies to the ultrasonic generator 100a. In FIG. 7, the horizontal axis represents frequency (f) and the vertical axis represents sharpness (Q). FIG. 7 shows three types of resonance characteristics. The broken line a represents the resonance characteristics of the vibrator 10 and the horn 11, the broken line i represents the resonance characteristics of the diaphragm 12, and the solid line c represents the resonance characteristics of the vibrator 10, the horn 11 and the diaphragm 12. As can be understood from FIG. 7, when the resonance characteristics of the respective members (the vibrator 10, the horn 11 and the diaphragm 12) match, the sharpness (Q) becomes sharp and the sound pressure level at the resonance frequency can be improved. become.

As described above, in the ultrasonic generator according to the first embodiment, the ultrasonic wave transmitted from the vibrator 10 is generated by causing the diaphragms (the diaphragm 12, the diaphragm 12a, and the diaphragm 12b) to “flexurally vibrate”. It vibrates at a specific frequency equivalent to the signal, and a strong sound (140 dB or more) having a specific ultrasonic band frequency is uniformly emitted from the entire surface of the diaphragm along the central axis of the vibrator 10. 30 cm or more). Further, by installing the reflection diaphragms (reflection diaphragms 22 to 26) with a predetermined interval K, strong ultrasonic waves radiated from the diaphragm are not attenuated between the reflection diaphragm and the diaphragm. Can be emitted repeatedly. The material of the diaphragm and the reflection diaphragm may be any material as long as it can vibrate at the vibration frequency in the ultrasonic region, regardless of metal or resin.

Embodiment 2. FIG.
FIG. 8 is a schematic configuration diagram showing a part of the configuration of the air purifier 200 according to Embodiment 2 of the present invention. Based on FIG. 8, the air cleaner 200 which is an example of the equipment provided with the ultrasonic generator (the ultrasonic generator 100 or the ultrasonic generator 100a) according to Embodiment 1 will be described. This air purifier 200 expands (aggregates) and removes dust particles contained in air taken inside by ultrasonic waves, and blows out the cleaned air to the outside. The case where the ultrasonic generator shown in FIG. 4 is mounted on the air cleaner 200, that is, the case where the reflection diaphragm 24 constitutes the housing surface of the air cleaner 200 will be described as an example. And

As shown in FIG. 8, the air cleaner 200 is provided with a dust collection filter 30 and a blower fan 31 in addition to the ultrasonic generator according to the first embodiment. The dust collection filter 30 collects dust contained in the air, and is preferably provided so as to be substantially orthogonal to the air flow. The blower fan 31 takes in air into the ultrasonic generator and blows out the cleaned air to the outside, and may be provided in any of the air flow paths in the air cleaner 200. The air purifier 200 takes air into the ultrasonic generator by the blower fan 31, aggregates the dust particles with ultrasonic waves (ultrasonic aggregation), collects the dust with the dust collecting filter 30, and cleans the air. Is.

仕組み Briefly explain the mechanism of ultrasonic aggregation. In the “dense” portion of the ultrasonic wave, which is a sparse / dense wave, air is rubbed by strong sound pressure radiation, and an electrostatic effect is generated. The dust passing through the “sound wall” existing in the ultrasonic wave generation region between the vibration plate 12 and the reflection vibration plate 23 and the ultrasonic wave generation region between the vibration plate 12 and the reflection vibration plate 24 is Under the influence of the electrostatic effect due to friction, the dust in the “sparse” part of the dense wave moves to the “dense” part and the particles expand (aggregate). In this way, ultrasonic agglomeration occurs. Moreover, in order to generate ultrasonic aggregation, it is a condition that powerful sound (140 dB or more) is emitted in the air. Therefore, the ultrasonic generator according to Embodiment 1 is installed to enable generation of ultrasonic aggregation.

If an air cleaner, such as one that performs large rotation of the blower fan and dust collection by a fine dust collection filter, can always generate ultrasonic agglomeration, the dust agglomeration effect will cause a coarse collection. The dust filter can also collect dust. That is, the necessity rule of a fine dust collection filter and a blower fan having a large rotation is not necessary. Therefore, in the air cleaner 200, since the ultrasonic generator according to the first embodiment is mounted, a large dust collection effect can be obtained even if the dust collection filter 30 is rough, and the blower fan 31 is rotated. It is possible to reduce the noise, and noise generation by a fan motor (not shown) for driving the blower fan 31 and the blower fan 31 can be reduced. Further, the air cleaner 200 can improve the dust collection effect without generating corona discharge.

In the second embodiment, the air cleaner 200 is illustrated and described as an example of the equipment provided with the ultrasonic generator according to the first embodiment. However, the ultrasonic generator according to the first embodiment is described as air. Equipment other than the cleaner 200 that uses ultrasonic waves, such as an air conditioner, an ultrasonic processing device, an ultrasonic atomizer, an ultrasonic bonding device, a distance measuring sensor, an ultrasonic cleaning device, an ultrasonic beauty device, etc. You can also Therefore, these equipments can radiate powerful sound (140 dB or more) evenly in the air, and by installing the reflective diaphragm, the powerful ultrasonic waves radiated from the diaphragm are reflected without being attenuated. It can be repeatedly radiated between the diaphragm and the diaphragm.

Claims

An ultrasonic transducer provided with a piezoelectric element;
An ultrasonic generator, comprising: a vibration plate that is attached to a tip portion of the ultrasonic vibrator and generates a ultrasonic wave by flexural vibration by resonating with vibration of the ultrasonic vibrator.
The diaphragm is
The ultrasonic generator according to claim 1, wherein the ultrasonic generator has a natural frequency that resonates due to vibration in a lattice mode or a parallel stripe mode.
The ultrasonic generator according to claim 1, further comprising a reflective diaphragm that is disposed to face the diaphragm at a predetermined interval and reflects sound radiation from the diaphragm.
The reflective diaphragm is
The ultrasonic generator according to claim 3, wherein the ultrasonic generator is fixed to a portion where a node of an ultrasonic signal transmitted from the ultrasonic transducer is generated.
A fixing member for fixing the reflection diaphragm;
The fixing member is
The ultrasonic generator according to claim 3, wherein the ultrasonic generator is installed in a portion where a node of an ultrasonic signal transmitted from the ultrasonic transducer is generated.
The predetermined interval is
6. The ultrasonic generator according to claim 3, wherein the distance is calculated by (wavelength / 2) * (order consisting of odd values) of the frequency generated by the diaphragm.
The ultrasonic generator according to any one of claims 3 to 6, wherein each of the diaphragm and the reflection diaphragm has a curved shape.
It has a horn that is open at both end faces and has an acoustic passage inside.
The horn is
The ultrasonic generator according to any one of claims 1 to 7, wherein the ultrasonic generator is attached between the ultrasonic transducer and the diaphragm.
An ultrasonic transducer provided with a piezoelectric element;
A vibration plate that is attached to the tip of the ultrasonic transducer and that flexibly vibrates by resonating with the vibration of the ultrasonic transducer and generates ultrasonic waves;
An ultrasonic wave generating apparatus, wherein an acoustic path is formed by bending the tip end side of the ultrasonic transducer at a predetermined angle.
The ultrasonic generator according to any one of claims 1 to 9,
An equipment having a housing on which the ultrasonic generator is mounted.
The equipment according to claim 10, wherein the reflective diaphragm constitutes the housing surface.