WO2016104414A1

WO2016104414A1 - Ultrasonic generation element and ultrasonic generation device provided with same

Info

Publication number: WO2016104414A1
Application number: PCT/JP2015/085652
Authority: WO
Inventors: 三谷　彰宏
Original assignee: 株式会社村田製作所
Priority date: 2014-12-26
Filing date: 2015-12-21
Publication date: 2016-06-30

Abstract

An ultrasonic generation element provided with a tabular frame (7) having an opening (7e) formed at the center, a tabular first oscillator (10) joined to one principal surface (7f1) of the frame (7), and a tabular second oscillator (11) joined to the other principal surface (7f2) of the frame (7), the ultrasonic generation element radiating an ultrasonic wave due to the oscillation of the first oscillator (10) and the second oscillator (11), the junction of the first oscillator (10) and the frame (7) and/or the junction of the second oscillator (11) and the frame (7) being achieved via an adhesive, and the opening (7e) being polygonal in plan view.

Description

Ultrasonic wave generating element and ultrasonic wave generating apparatus having the same

The present invention relates to an ultrasonic generator and an ultrasonic generator provided with the same.

Conventionally, ultrasonic generators may be used for non-contact distance measurement purposes. An example of an ultrasonic generator is described in International Publication No. WO2013 / 125212A1 (Patent Document 1). The ultrasonic generator includes an ultrasonic generator that generates ultrasonic waves and a case. The case has a structure in which a cap-like second case material is combined on a flat plate-like first case material, and has a storage space inside. The ultrasonic wave generating element is stored in this storage space. The top plate portion of the second case material is provided with a plurality of sound wave emission holes. The ultrasonic wave generating element includes a spacer in which an opening that is a through hole is formed in a central region, and a bimorph piezoelectric vibrator that is bonded to the upper and lower surfaces of the spacer with an adhesive. The ultrasonic wave generating element is fixed on the first case material via a plurality of support members.

International Publication WO2013 / 125212A1

The sound pressure for each frequency greatly depends on the resonance frequency of the ultrasonic generator. In order to stabilize the variation in individual sound pressure at a specific frequency, it is necessary to suppress the variation in the resonance frequency. In the ultrasonic wave generating element in which the piezoelectric vibrator is bonded to the upper and lower surfaces of the spacer in which the opening is formed as described above, the resonance frequency is substantially determined by the thickness of the piezoelectric vibrator and the dimension of the opening of the spacer. Therefore, once the piezoelectric vibrator and the spacer are bonded together, it is difficult to adjust the resonance frequency. In order to make the resonance frequency equal to a desired value, it is necessary to strictly set the tolerance of the thickness of the piezoelectric vibrator and the dimension of the opening of the spacer, but there is a limit to the processing accuracy.

Therefore, an object of the present invention is to provide an ultrasonic wave generation element capable of reducing variation in resonance frequency and an ultrasonic wave generation apparatus including the same.

In order to achieve the above object, an ultrasonic wave generating element according to the present invention includes a flat frame body having an opening at the center and a flat first plate joined to one main surface of the frame body. And a flat plate-like second vibrator bonded to the other main surface of the frame, and the ultrasonic wave is generated by the vibration of the first vibrator and the second vibrator. An ultrasonic wave generating element to be emitted, wherein at least one of bonding between the first vibrator and the frame and bonding between the second vibrator and the frame is performed via an adhesive. The opening is polygonal when viewed in plan.

According to the present invention, since the shape of the opening when viewed in plan is a polygon, at least of the joint between the first vibrator and the frame and the joint between the second vibrator and the frame. The substantial diameter of the inscribed circle can be avoided as much as possible due to the adhesive protruding from one side, and as a result, the variation in resonance frequency can be reduced.

It is a perspective view of the ultrasonic wave generation element in Embodiment 1 based on this invention. It is arrow sectional drawing regarding the II-II line | wire in FIG. It is an exploded view of the ultrasonic wave generation element in Embodiment 1 based on this invention. It is explanatory drawing of the phenomenon which arises when a frame has a circular opening part. It is explanatory drawing of the phenomenon which arises when a frame has a square opening part. It is explanatory drawing of the phenomenon which arises when a frame has an octagonal opening part. It is an exploded view of the ultrasonic wave generation element in Embodiment 2 based on this invention. It is an exploded view of the ultrasonic wave generation element in Embodiment 3 based on this invention. It is an exploded view of the ultrasonic wave generation element in Embodiment 4 based on this invention. It is a graph which shows the relationship between the cavity tolerance in the opening part of various shapes, and the variation | change_quantity of the resonant frequency. It is a histogram which shows the fluctuation range of the resonant frequency in the opening part of various shapes. It is a top view of the frame with which the ultrasonic wave generation element in Embodiment 5 based on this invention is provided. It is an exploded view of the ultrasonic wave generation element in Embodiment 6 based on this invention. It is a side view of the ultrasonic wave generation element in Embodiment 6 based on this invention. It is a side view of the 1st modification of the ultrasonic wave generation element in Embodiment 6 based on this invention. It is a side view of the 2nd modification of the ultrasonic wave generation element in Embodiment 6 based on this invention. It is a side view of the 3rd modification of the ultrasonic wave generation element in Embodiment 6 based on this invention. It is a side view of the 4th modification of the ultrasonic wave generation element in Embodiment 6 based on this invention. It is a perspective view of the ultrasonic generator in Embodiment 7 based on this invention. FIG. 20 is a cross-sectional view taken along the line XX-XX in FIG. 19. It is an exploded view of the ultrasonic generator in Embodiment 7 based on this invention. It is a top view which shows the positional relationship of the frame body contained in the ultrasonic generator in Embodiment 7 based on this invention, and a supporting member. It is a top view which shows the positional relationship of the frame body and support member which are contained in the 1st modification of the ultrasonic generator in Embodiment 7 based on this invention. It is a top view which shows the positional relationship of the frame body and support member which are contained in the 2nd modification of the ultrasonic generator in Embodiment 7 based on this invention. It is a top view of the 1st example of the frame which has the polygonal opening part which the corner rounded. It is a top view of the 2nd example of the frame which has the polygonal opening part in which the corner | round became round.

In order to reduce the variation of the resonance frequency, it is conceivable to increase the thickness of the piezoelectric vibrator and the size of the opening of the spacer included in the ultrasonic generation element. There are limits. Therefore, the inventor has studied a structure capable of suppressing the influence of the processing error, and has come to make the present invention.

In addition, when referring to the upper and lower concepts in this specification, the upper and lower concepts used here are relative ones used for convenience of explanation, and do not mean absolute up and down.

(Embodiment 1)
With reference to FIGS. 1 to 3, an ultrasonic wave generating element according to the first embodiment of the present invention will be described. FIG. 1 shows the entire ultrasonic wave generating element 101 in the present embodiment. FIG. 2 shows a cross-sectional view taken along the line II-II in FIG. FIG. 3 shows a state where the ultrasonic wave generating element 101 is disassembled.

The ultrasonic wave generating element 101 according to the present embodiment includes a flat frame body 7 having an opening 7e formed at the center, and a flat plate-like first vibration bonded to one main surface 7f1 of the frame body 7. A child 10 and a flat second vibrator 11 joined to the other main surface 7f2 of the frame 7 are provided. The ultrasonic wave generating element 101 is an ultrasonic wave generating element that emits ultrasonic waves when the first vibrator 10 and the second vibrator 11 vibrate. At least one of the bonding between the first vibrator 10 and the frame 7 and the bonding between the second vibrator 11 and the frame 7 is performed via an adhesive, and the opening 7e is formed on the frame 7. It is a polygon when viewed in plan from above the main surface.

As shown in FIG. 2, the first vibrator 10 includes a piezoelectric plate 10a,

excitation electrodes

10c and 10d formed as electrode patterns on the upper and lower surfaces of the piezoelectric plate 10a, and an electrode pattern inside the piezoelectric plate 10a. And an arranged internal electrode 10b. The excitation electrode 10c and the internal electrode 10b include portions facing each other across a part of the piezoelectric plate 10a. The internal electrode 10b and the excitation electrode 10d include portions that face each other across a part of the piezoelectric plate 10a.

The second vibrator 11 includes a piezoelectric plate 11a,

excitation electrodes

11c and 11d formed as electrode patterns on the upper and lower surfaces of the piezoelectric plate 11a, and an internal electrode 11b arranged as an electrode pattern inside the piezoelectric plate 11a. Is provided. The excitation electrode 11c and the internal electrode 11b include portions facing each other across a part of the piezoelectric plate 11a. The internal electrode 11b and the excitation electrode 11d include portions that face each other across a part of the piezoelectric plate 11a.

In general, in an ultrasonic wave generating element having a structure in which vibrators are attached to both sides of a frame body in which openings are formed, the internal space of the opening of the frame body is a so-called “cavity”. The first vibrator and the second vibrator exist as walls that separate the cavity from the outside, and so-called drum-shaped vibration occurs in the first vibrator and the second vibrator. In the case of drum-shaped vibration, the vibrator vibrates in a circular shape. In this case, the diameter of the inscribed circle with respect to the opening of the frame is an effective cavity size.

In the present embodiment, since the internal space of the opening 7e becomes a cavity, the diameter of the inscribed circle with respect to the opening 7e is an effective cavity size. By the way, in the present embodiment, an adhesive is used for at least one of the bonding between the first vibrator 10 and the frame body 7 and the bonding between the second vibrator 11 and the frame body 7. In this configuration, a phenomenon that a part of the adhesive protrudes inside the opening 7e can occur. As shown in FIG. 4, when the frame body 7 has a circular opening 7e1, the adhesive protrudes inside the opening 7e1, so that it is different from the diameter D1 of the opening 7e as originally designed. The diameter of the inscribed circle 32 affected by the protruding adhesive 31 is D2. Since D1> D2, the diameter D2 is an effective cavity size. Thus, the diameter of the substantial inscribed circle is changed by the protruding adhesive.

However, in the present embodiment, since the opening has a polygonal shape when viewed in plan, the degree of influence on the diameter of the inscribed circle is small even if the adhesive protrudes somewhat. When the opening has a polygonal shape, the protrusion of the adhesive tends to occur more easily at each vertex than in the middle of each side. For example, when the opening is a square as an easy-to-understand example, the situation is like the opening 7e2 shown in FIG. The protruding adhesive 31 is distributed in an irregular size in the vicinity of the apex of the opening 7e2, but the inscribed circle 32 is thus fixed regardless of the presence or absence of the adhesive 31. Even if the adhesive 31 protrudes in the vicinity of the apex, the diameter of the inscribed circle 32 is not easily changed.

Even in the configuration shown in FIG. 5, the diameter of the inscribed circle may be affected if the adhesive protrudes at the center of either side. It can be said that the probability of being affected is greatly reduced compared to the situation where the diameter of the inscribed circle is immediately affected regardless of where the adhesive protrudes. According to the present embodiment, it is possible to adopt a configuration that is not easily affected by the protrusion of the adhesive.

In the present embodiment, the opening 7e is octagonal as shown in FIG. 3, but in this case as well, the adhesive 31 protrudes in the vicinity of the apex of the octagon as shown in FIG. Even so, the diameter of the inscribed circle 32 is unlikely to fluctuate. Therefore, it can be set as the structure which is hard to receive the influence by the protrusion of an adhesive agent. The fact that the diameter of the inscribed circle 32 does not easily change means that the probability that the inscribed circle diameter as designed is secured is increased, and the probability that the resonance frequency varies due to the processing error of the opening 7e is reduced. .

Therefore, in the present embodiment, it is possible to realize an ultrasonic wave generating element that can reduce variations in resonance frequency.

In the present embodiment, it is preferable that the first vibrator 10 and the second vibrator 11 vibrate in the buckling tuning fork vibration mode with phases opposite to each other. In this case, the diameter of the inscribed circle is particularly important, and it becomes more effective to avoid fluctuations in the diameter of the inscribed circle due to the protruding adhesive.

(Embodiment 2)
With reference to FIG. 7, the ultrasonic wave generation element in Embodiment 2 based on this invention is demonstrated. FIG. 7 shows an exploded view of the ultrasonic wave generating element in the present embodiment.

In the present embodiment, the frame 7 included in the ultrasonic wave generating element has a square opening 7ei.

Also in the present embodiment, the same effect as in the first embodiment can be obtained. In the present embodiment, since the shape of the opening 7ei is a square, there are only four points where the inscribed circle of the opening and the inner periphery of the opening are in contact. There are only two places that specify the diameter of the inscribed circle in the vertical and horizontal directions. Therefore, the probability that the diameter is affected by the protruding adhesive can be reduced. The smaller the number of locations where the inscribed circle of the opening and the inner periphery of the opening are in contact with each other, the lower the probability of being affected by the protruding adhesive.

In the present embodiment, the area of the opening can be increased as compared with the first embodiment.

(Embodiment 3)
With reference to FIG. 8, the ultrasonic wave generation element in Embodiment 3 based on this invention is demonstrated. FIG. 8 shows an exploded view of the ultrasonic wave generating element in the present embodiment.

In the present embodiment, the frame 7 included in the ultrasonic wave generating element has a regular hexagonal opening 7ej.

Also in the present embodiment, the same effect as in the first embodiment can be obtained. In the example shown in FIG. 8, the strength of the frame is somewhat inferior because a part of the frame is extremely narrowed.

In addition, although the shape of the opening 7ej is a regular hexagon here, it may be a hexagon other than a regular hexagon. In the first place, the shape of the opening provided in the frame is not necessarily a regular polygon.

(Embodiment 4)
With reference to FIG. 9, the ultrasonic wave generation element in Embodiment 4 based on this invention is demonstrated. FIG. 9 shows an exploded view of the ultrasonic wave generating element in the present embodiment.

In the present embodiment, the frame 7 included in the ultrasonic wave generating element has a regular dodecagonal opening 7ek.

Also in the present embodiment, the same effect as in the first embodiment can be obtained.
In each of the embodiments described so far, the opening provided in the central portion of the frame body 7 is a polygon when viewed in plan, but the polygon may have the following characteristics. preferable. When the polygon is an n-gon, n is preferably an integer of 4 or more and 12 or less. When n = 3, the opening is a triangle. However, if the opening is a triangle while the size of the inscribed circle of the opening is kept constant, the opening becomes a considerably large triangle. Accordingly, the outer shape of the ultrasonic wave generating element becomes considerably large, which hinders space saving. Further, when n ≦ 2, it does not hold as a polygon. Conversely, the more n, the closer to a circle. In particular, when n ≧ 13, the polygonal n-gon is very close to a circle, and the probability of the protruding adhesive entering the inside of the inscribed circle increases. In other words, the effect of the present invention is diminished. Therefore, n is preferably an integer of 4 or more and 12 or less.

A simulation was performed for each of the case where n = 4, 6, 8, 12 in the shape of the opening and the case where the opening was circular, and the relationship between the cavity tolerance and the amount of change in the resonance frequency was investigated. The results are shown in FIG. It can be seen that the slope of the change becomes gentler by decreasing n, such as an octagon, a hexagon, and a quadrangle, compared to the case where the shape of the opening is circular. Even under the same cavity tolerance, the smaller the n is, the smaller the change width of the resonance frequency can be suppressed.

Also, FIG. 11 shows a histogram of results obtained by actually preparing a sample of an ultrasonic wave generating element and actually measuring it. The variation width of the resonance frequency in each sample was examined in the case where each of the openings was circular, octagonal, or quadrangular. The average value and the variance are shown in Table 1.

According to FIG. 11, it can be seen that the variation becomes smaller as n becomes smaller from circular to octagonal, quadrilateral.

As shown in Embodiment 1, the polygon is preferably an octagon. By adopting this configuration, it is not necessary to extremely increase the outer diameter of the frame body, and the effect of the present invention can be enjoyed without having a portion with extremely weak strength. In addition, when the outer shape of the frame is a rectangle (including a square as a matter of course), if the opening is an octagon, the four sides of the opening are arranged in parallel with the four sides and supported at the four corners. This is preferable because a large connection location of the member (described later in detail) can be secured.

N which defines the shape of the opening need not be an even number, and may be an odd number. For example, even a triangle can cause a desired vibration.

In the embodiments described so far, for the convenience of explanation, the outer shape of the frame is assumed to be a rectangle. However, the outer shape of the frame is not necessarily a rectangle.

(Embodiment 5)
With reference to FIG. 12, the ultrasonic wave generation element in Embodiment 5 based on this invention is demonstrated. The configuration of the ultrasonic wave generating element in the present embodiment is basically the same as that described in the first embodiment, but differs in the following points.

This ultrasonic wave generating element includes a frame body 7 as shown in FIG. The frame body 7 has an octagonal opening.

If the sides arranged along the outer periphery of the octagon of the opening are referred to as first to eighth sides 41 to 48 in order, the first, third, fifth, and

seventh sides

41, 43, 45, 47 is a first length, and the second, fourth, sixth, and

eighth sides

42, 44, 46, and 48 are second lengths different from the first length, respectively. The interior angle at each vertex is 135 °.

Also in the present embodiment, the same effect as in the first embodiment can be obtained. Even if the shape of the opening is an octagon, it does not have to be a regular octagon. In the present embodiment, the shape of the opening is an octagon as shown in FIG. 12, and it is preferable because a large area for overlapping the support member can be secured at the four corners of the frame body while ensuring a large area of the opening.

(Embodiment 6)
With reference to FIG. 13 and FIG. 14, the ultrasonic wave generation element in Embodiment 6 based on this invention is demonstrated. The configuration of the ultrasonic generating element in the present embodiment is basically the same as that described in the first exemplary embodiment, but differs in the following points.

FIG. 13 shows an exploded view of the ultrasonic wave generating element in the present embodiment. The frame body 7 included in the ultrasonic wave generating element in the present embodiment has an opening 7en. The frame body 7 has an air vent 7d that allows the opening 7en and the outside to communicate with each other when seen in a plan view. FIG. 14 shows a side view seen from the side where the vent 7d is opened. The vent 7 d is sandwiched between the first vibrator 10 and the second vibrator 11.

In the present embodiment, since the frame 7 is provided with the vent 7d, air or the like can flow inside and outside the cavity through the vent 7d. Therefore, even if the ultrasonic wave generating element is exposed to a high temperature and water vapor or the like in the cavity expands, the ultrasonic wave generating element itself can be prevented from being destroyed.

The following are some modifications of the vent. As shown in FIG. 15, a structure in which a vent is formed by closing a groove formed on one main surface of the frame body 7 with one vibrator is also possible. In this example, the vent hole 7 d 1 is formed by covering the groove provided in the frame body 7 with the first vibrator 10.

As shown in FIG. 16, the vent 7d2 may be formed by a through hole provided in the side surface of the frame body 7 without communicating with the upper and lower main surfaces of the frame body 7.

As shown in FIG. 17, the air vent may be formed by closing a groove having a semicircular cross-sectional shape formed on one main surface of the frame body 7 with one vibrator. In this example, the vent hole 7d3 is formed by covering the groove provided in the frame body 7 with the first vibrator 10.

A vent hole may be formed by closing a groove having a triangular cross-sectional shape formed on one main surface of the frame body 7 with one vibrator as in the vent hole 7d4 shown in FIG. . In this example, the vent 7d4 is formed by covering the groove provided in the frame body 7 with the first vibrator 10.

(Embodiment 7)
With reference to FIGS. 19 to 21, an ultrasonic generator according to Embodiment 7 of the present invention will be described. The ultrasonic generator according to the present embodiment includes any of the ultrasonic generators described in the previous embodiments.

FIG. 19 shows a perspective view of the ultrasonic generator 301 in the present embodiment. FIG. 20 is a cross-sectional view taken along the line XX-XX in FIG. An exploded view of the ultrasonic generator 301 is shown in FIG.

The ultrasonic generator 301 has a storage space 35 inside, the case 1 having sound

wave emission holes

3 a, 3 b, 3 c, 3 d for communicating the storage space 35 with the outside, and the storage space 35. The ultrasonic generator according to any one of the above embodiments is provided. Case 1 includes a base substrate 2 and a cap member 3. The storage space 35 is defined by a combination of the base substrate 2 and the cap member 3. The cap member 3 has sound

wave emitting holes

3a, 3b, 3c, 3d. In the example shown here, the sound

wave emission holes

3a, 3b, 3c, 3d are all elongated rectangular openings.

The ultrasonic generator 301 includes an ultrasonic generator 101. Therefore, as shown in FIG. 21, the ultrasonic generator 301 includes a frame 7 having an octagonal opening 7e. Here, the opening is an octagon as an example, but the shape of the opening is not limited to an octagon and may be a polygon.

As shown in FIG. 21, the first vibrator 10 is bonded to one main surface of the frame body 7 through an adhesive layer 8. The second vibrator 11 is bonded to the other main surface of the frame body 7 via the adhesive layer 9.

As shown in FIG. 21, a land electrode 4 is provided on the upper surface 2 u of the base substrate 2. A support member 5 is disposed on the land electrode 4, and the ultrasonic wave generating element 101 is placed on the upper side of the support member 5. The ultrasonic wave generating element 101 is fixed to the base substrate 2 via the support member 5. As shown in FIG. 20, a conductive film is provided on the side surface of the ultrasonic wave generating element 101, and the conductive adhesive 12 is disposed so as to electrically connect the conductive film and the base substrate 2. Has been.

According to the present embodiment, since the opening of the frame is polygonal, it is possible to provide an ultrasonic generator that is less affected by the sticking out of the adhesive and can reduce variations in resonance frequency.

Ultrasonic waves generated by the ultrasonic wave generating element 101 proceed as indicated by broken line arrows in FIG. 20, and are emitted to the outside through the sound

wave emission holes

3a, 3b, 3c, and 3d provided in the cap member 3.

As shown in FIG. 20, the ultrasonic wave generating element 101 is installed on the inner surface of the case 1 via the support member 5, and the support member 5 is planar from above the main surface of the frame body 7 as shown in FIG. 22. It is preferable to arrange so as to avoid the area inside the opening 7e. In FIG. 22, only the frame body 7 and the support member 5 are extracted and displayed among the constituent elements of the ultrasonic wave generation element 101 in order to explain the positional relationship when viewed in plan. In the example shown in FIG. 22, the outer shape of the frame body 7 is preferably square and the opening 7 e is octagonal. Therefore, the support member 5 can be stably disposed using the remaining portions of the four corners. Is done. Thus, if the support member 5 is arranged so as to avoid the region inside the opening 7e when viewed in plan, the presence of the support member 5 affects the diameter of the substantially inscribed circle of the opening. Can be avoided. Therefore, the ultrasonic wave generation element 101 can reduce the variation in the resonance frequency, and the ultrasonic wave generation apparatus 301 including the support member 5, the case 1, and the like can also reduce the variation in the resonance frequency. .

As illustrated here, the outer shape of the ultrasonic generating element when viewed in plan is a square, the support member 5 includes four support member pieces, and the four support member pieces are formed at the four corners of the square. It is preferable that they are dispersedly arranged so as to correspond to each other. The example shown in FIG. 22 is an example that exactly satisfies this condition, and can obtain a preferable effect as described above.

In addition, the following can be illustrated as another modification of the structure in which the supporting member 5 includes four supporting member pieces. 23 to 24, in order to explain the positional relationship, only the frame body 7 and the support member 5 are extracted and displayed in a plan view. For example, a configuration as shown in FIG. The frame body 7 has a rectangular opening 7ei. Each support member piece included in the support member 5 has an L shape. Also in the example shown in FIG. 23, the support member 5 is arranged so as to avoid the area inside the opening 7ei when seen in a plan view.

A configuration as shown in FIG. The frame 7 has a hexagonal opening 7ej. Also in the example shown in FIG. 24, the support member 5 is arranged so as to avoid the area inside the opening 7ej when seen in a plan view. Here, the support member 5 is shown as including four support member pieces. However, depending on the shape of the opening of the frame, the support member may be formed by a combination of a number of support member pieces other than four.

In each of the above embodiments, when the opening of the frame 7 is a polygon, it is not limited to an accurate polygon but includes a shape that can be regarded as a polygon. The same applies when referring to an n-gon for a particular integer n. For example, as shown in FIG. 25 and FIG. 26, a shape with rounded corners is also included in the polygon. The shape of the opening of the frame 7 shown in FIG. 25 is a quadrangular shape with rounded corners, but this level is included in the quadrilateral concept. The shape of the opening of the frame 7 shown in FIG. 26 is an octagon with rounded corners, but this level is included in the concept of an octagon.

In addition, you may employ | adopt combining suitably two or more among the said embodiment.
In addition, the said embodiment disclosed this time is an illustration in all the points, Comprising: It is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 case, 2 base substrate, 2u top surface, 3 cap member, 3a-3d sound wave emission hole, 4 land electrode, 5 support member, 7 frame body, 7d, 7d1, 7d2, 7d3, 7d4 vent hole, 7e, 7e1, 7e2 , 7ei, 7ej, 7ek, 7en opening, 7f1 one main surface, 7f2 other main surface, 8, 9 adhesive layer, 10 first vibrator, 10a, 11a piezoelectric plate, 10b, 11b internal electrode, 10c , 10d, 11c, 11d Excitation electrode, 11 Second vibrator, 12 Conductive adhesive, 31 (Extruded) adhesive, 32 Inscribed circle, 35 Internal space, 41-48 First to eighth sides, 101 Ultrasonic generator, 301 Ultrasonic generator.

Claims

A flat frame with an opening formed in the center;
A flat plate-like first vibrator joined to one main surface of the frame;
A flat plate-like second vibrator joined to the other main surface of the frame,
An ultrasonic wave generating element that emits ultrasonic waves when the first vibrator and the second vibrator vibrate,
At least one of the bonding between the first vibrator and the frame and the bonding between the second vibrator and the frame is performed via an adhesive,
The ultrasonic wave generating element, wherein the opening is polygonal when viewed in plan.
The ultrasonic generator according to claim 1, wherein the first vibrator and the second vibrator vibrate in a buckled tuning fork vibration mode in mutually opposite phases.
The ultrasonic generator according to claim 1 or 2, wherein n is an integer of 4 to 12, assuming that the polygon is an n-gon.
The ultrasonic generator according to claim 1 or 2, wherein the polygon is an octagon.
If the sides arranged along the outer periphery in the octagon are referred to as first to eighth sides in order, all of the first, third, fifth, and seventh sides have the first length, 5. The ultrasonic generator according to claim 4, wherein each of the second, fourth, sixth, and eighth sides has a second length different from the first length, and an inner angle at each vertex is 135 °. .
The ultrasonic generator according to any one of claims 1 to 5, wherein the frame has a vent hole that allows the opening and the outside to communicate with each other when seen in a plan view.
A case having a storage space inside, and having a sound wave emitting hole for communicating the storage space with the outside;
The said ultrasonic generator provided with the ultrasonic wave generation element in any one of Claim 1 to 6 accommodated in the said storage space.
The ultrasonic generating element is installed on an inner surface of the case via a support member, and the support member is disposed so as to avoid a region inside the opening as seen in a plan view. Ultrasonic generator.
The outer shape of the ultrasonic wave generating element when viewed in plan is a square, the support member includes four support member pieces, and the four support member pieces are distributed so as to correspond to the four corners of the square, respectively. The ultrasonic generator according to claim 8, which is arranged.