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JP2011015271

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DESCRIPTION JP2011015271
An object of the present invention is to realize low-frequency acoustic radiation and to realize
miniaturization and weight reduction of an acoustic transducer. SOLUTION: In an acoustic
transducer 1a emitting a sound wave to a medium M such as air or water, a shaft (shaft member)
2 extending to a central portion of the acoustic transducer 1a and a shaft 2 alternately in a radial
direction Of the first and second acoustic radiation plates 4 and 5 and the shaft 2 arranged in the
same axial direction, the shaft 2 and the channel 3 And the first acoustic radiation plate 5 is
curved outward in cross-sectional shape in a plane intersecting the axis of the shaft member, and
the bending vibration plate (plate member) 7 is connected to the piezoelectric vibrator (vibrator)
8. The cross-sectional shape of the second acoustic radiation plate 6 in the plane intersecting the
axis of the shaft member is curved outward. [Selected figure] Figure 1
Acoustic transducer
[0001]
The present invention relates to an acoustic transducer (electro-acoustic transducer) that emits
sound waves into the air or water, and more particularly to an acoustic transducer that can
efficiently emit sound waves at low frequencies.
[0002]
Acoustic transducers that emit sound waves into media such as water are used in areas such as
oceanographic observation.
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The lower the frequency of the sound wave used, the lower the attenuation, the better the
propagation characteristics, and the longer the distance the sound can be emitted. In recent
years, therefore, much of the medium such as water around the acoustic emission surface should
be excluded. Acoustic transducers that emit low-frequency sound waves have been put to
practical use.
[0003]
Conventional acoustic transducers used in water include a bolted Langevin transducer, a
cylindrical transducer, a flextensional transducer, a bending disk transducer, and a barrel stave
transducer.
[0004]
According to Non-Patent Document 1, a bolt-clamped Langevin transducer (also referred to as a
Tonpilz type transducer due to its shape) 101 shown in FIGS. 9A and 9B includes a vibrator
module 103 including a plurality of annular piezoelectric vibrators 102. An acoustic radiation
plate 104 is provided at one end face of the sensor.
Then, the transducer module 103 itself radiates sound from the acoustic radiation plate 104
using a vibration mode in which the longitudinal oscillation of 1⁄2 wavelength is performed.
Further, in the cylindrical transducer 111 shown in FIGS. 10A and 10B, an acoustic radiation
plate 114 is provided on the outer peripheral surface of the cylindrical vibrator 112. Then,
acoustic radiation is emitted from the acoustic radiation plate 114 using a respiratory vibration
mode in the radial direction of the cylindrical vibrator 112 itself, that is, a mode in which
longitudinal vibration of one wavelength is formed on the circumferential length of the cylinder.
[0005]
Further, the flextensional type transducer 121 shown in FIGS. 11A and 11B does not radiate the
sound wave directly into water utilizing the resonance of the vibrator itself, but the cross section
of the vibration of the vibrator 122 is The vibration is converted into bending vibration of the
bending acoustic radiation plate 124 using an elliptical shell to expand the amplitude, and the
bending vibration of the bending acoustic radiation plate 124 is used to acoustically emit the
displacement generated by the vibrator 122 . Further, according to Patent Document 1, the
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bending disk type transducer 131 shown in FIG. 12 adheres the disk-like vibrator 132 to the
bending acoustic radiation plate 134 and uses the flexural resonance of the bending acoustic
radiation plate 134 etc. Thus, the displacement generated by the vibrator 132 is acoustically
radiated. The acoustic transducers 121 and 131 can eliminate many media by using the bending
acoustic emission plates 124 and 134 utilizing bending vibration which can easily obtain a
resonance frequency at a lower frequency than longitudinal vibration.
[0006]
Further, according to Patent Document 2, a plurality of bent sound emission plates 144 are
disposed on the outer peripheral portion of the barrel-stayed transducer 141 shown in FIG. 13,
and a gap d1 is formed between adjacent sound emission plates 144. Is provided.
[0007]
On the other hand, an electrodynamic speaker (acoustic transducer) generally used in the air
transmits the vibration of a coil vibrated by electromagnetic force to cone paper, and performs
acoustic radiation from cone paper.
In acoustic radiation to air, since the acoustic radiation impedance is small, it is possible to
secure a large medium exclusion volume with a lightweight material such as paper.
[0008]
Patent document 1: JP-A-5-344582 U.S. Pat.
[0009]
"Basics and applications of ocean acoustics (edited by the Japan Acoustical Society)",
Naruyamado Shoten, April 28, 2004, p. 58-60
[0010]
However, conventional acoustic transducers have the following problems.
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In order to increase the medium displacement volume in the bolted Langevin transducer 101
shown in FIG. 9 and the cylindrical transducer 111 shown in FIG. 10, it is necessary to increase
the displacement of the acoustic radiation plate by increasing the length and diameter of the
vibrator. There is a problem that the size of the acoustic transducer itself is increased and the
weight is increased.
Therefore, at present, these acoustic transducers are used at a frequency of approximately 1 kHz
or more due to limitations such as dimensions.
[0011]
Further, in the flextensional type transducer 121 shown in FIG. 11 and the bending disk type
transducer 131 according to Patent Document 1 shown in FIG. 12, in order to increase the
medium excluded volume, it is necessary to increase the area of the acoustic radiation plate. Also
in this case, the size and weight of the acoustic transducer itself increase. In particular, when a
piezoelectric ceramic having a large mass is used for the flexural diaphragm, a structure having a
large mass in a place having a large amplitude is obtained, and a low resonant frequency can be
obtained. Has a problem in that it is not suitable for broad band acoustic radiation.
[0012]
Also, since the barrel-stave type transducer 141 shown in FIG. 13 requires a gap between
adjacent acoustic radiation plates, when the whole is molded for watertightness, the vibration of
the gap d1 is inhibited by water pressure and the efficiency of acoustic radiation is improved. It
sometimes fell. In addition, even in the case of an electrodynamic speaker used in the air, in order
to increase the medium discharge volume, a larger cone paper is used, resulting in an increase in
the size of the speaker. Further, even in the case of a system in which a piezoelectric vibrator is
bonded to a diaphragm to emit sound as in a piezoelectric speaker, it is necessary to increase the
diameter of the diaphragm in order to increase the medium excluded volume.
[0013]
In addition, when the underwater vehicle or towing body is equipped with an acoustic
transducer, it is desirable that its specific gravity be close to or rather smaller than that of the
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medium (water). If the specific gravity is larger than the medium, the underwater vehicle requires
a buoyancy material for floating the acoustic transducer, and the tow body with a space for
providing the buoyancy body may drop the acoustic transducer. Conventional acoustic
transducers capable of low-frequency acoustic radiation often use a piezoelectric ceramic as a
vibrator, and their specific gravity is 1 or more.
[0014]
The present invention has been made in view of the above-mentioned problems, and it is an
object of the present invention to provide an acoustic transducer capable of efficiently excluding
the medium around the acoustic radiation plate without increasing the shape of the vibrator and
the acoustic radiation plate I assume.
[0015]
In order to achieve the above object, an acoustic transducer according to the present invention
comprises an axial member extending in the center of the acoustic transducer and an axial
direction around the axial member. And four or more even channels arranged in the same
direction, and an acoustic radiation plate in a shape obtained by radially dividing a cylinder
disposed between the adjacent channels, the vibrator connected to the shaft member and the
channel, and a vibrator And the acoustic radiation plate curved in the direction approaching the
shaft member and the acoustic radiation plate curved in the direction away from the shaft
member are alternately disposed.
[0016]
According to the present invention, it is possible to efficiently eliminate the medium around the
acoustic radiation surface without increasing the size of the acoustic radiation plate or the
vibrator, so that low-frequency acoustic radiation can be performed and the acoustic transducer
can be miniaturized. can do.
[0017]
(A) is a figure which shows an example of the acoustic transducer by 1st embodiment of this
invention, (b) is the sectional view on the AA line of (a).
(A), (b) is a figure explaining operation ¦ movement of the acoustic transducer shown in FIG.
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(A) thru ¦ or (c) is a figure which shows the arrangement ¦ positioning method of the piezoelectric
vibrator by 1st embodiment.
It is a figure which shows an example of the acoustic transducer by 2nd embodiment. (A), (b) is a
figure which shows the arrangement ¦ positioning method of the piezoelectric vibrator by 2nd
embodiment. It is a figure which shows an example of the acoustic transducer by 3rd
embodiment. (A) is a figure which shows an example of the acoustic transducer by 4th
embodiment, (b) is a BB sectional drawing of (a). It is a figure which shows an example of the
acoustic transducer by 5th embodiment. (A) is a figure which shows the conventional bolted
Langevin type ¦ mold acoustic transducer, (b) is the CC sectional view taken on the line of (a). The
figure which shows the conventional cylindrical acoustic transducer, (b) is the DD sectional view
taken on the line of (a). FIG. 6 is a view showing a conventional flextensional type acoustic
transducer, and FIG. 7 (b) is a cross-sectional view taken along the line E-E of FIG. The figure
which shows the conventional bending disk type acoustic transducer, (b) is the FF sectional view
taken on the line of (a). The figure which shows the conventional barrel stave type acoustic
transducer, (b) is the GG sectional view taken on the line of (a).
[0018]
Hereinafter, an acoustic transducer according to a first embodiment of the present invention will
be described based on FIGS. 1 to 3. As shown in FIG. 1 (a), in the acoustic transducer 1a
according to the first embodiment, eight channels 3 are arranged in the same axial direction
around a shaft (shaft member) 2 extending in the center portion. It is set up. The shaft 2 is
formed longer in the axial direction than the channel 3, and the distal end portion 2 a of the shaft
2 and the distal end portion 3 a of each channel 3 are connected by the connecting member 4.
First and second acoustic radiation plates 5, 6 are alternately arranged between the channels 3
adjacent in the circumferential direction around the shaft 2.
[0019]
The first and second acoustic radiation plates 5 and 6 are members that are flexible and emit
sound waves to the medium M such as water. When the first acoustic radiation plate 5 is
disposed between the adjacent channels 3 or the coupling members 4, the first acoustic radiation
plate 5 is curved radially outward (the medium M side). When the second acoustic radiation plate
6 is disposed between the adjacent channels 3 or the connecting members 4, the second acoustic
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radiation plate 6 is curved inward in the radial direction (shaft 2 side). Here, with respect to the
first and second acoustic radiation plates 5 and 6 disposed, the shaft 2 side is the inner side, and
the medium M side is the outer side.
[0020]
In addition, the curvature radius of the third acoustic radiation plate 5a, the second acoustic
radiation plate 6, and the bottom surface, which form a partial conical surface having the same
curvature radius as that of the first acoustic radiation plate 5 between adjacent connection
members 4 The fourth acoustic radiation plates 6a having the same partial conical surface are
alternately disposed. The first, second, third and fourth acoustic radiation plates 5, 6, 5a, 5b are
members made of a synthetic resin or a material containing a synthetic resin, and have a
honeycomb structure.
[0021]
As shown in FIG. 1B, a plate-like bending diaphragm 7 is radially disposed around the shaft 2,
and the bending diaphragm 7 is connected to the shaft 2 and the channel 3. A plate-like
piezoelectric vibrator (vibrator) 8 is bonded to one side of the flexural diaphragm 7. The flexural
diaphragm 7 and the piezoelectric vibrator 8 form a flexural vibration module 9 having a
unimorph structure. The flexural diaphragm 7 is connected to the first and second acoustic
radiation plates 5, 6 via a channel 3. The channel 3 and the flexural diaphragm 7 are formed of a
synthetic resin or a material containing a synthetic resin, and are members of a honeycomb
structure or a laminated structure. The channel 3 may be formed of a high density material such
as metal or ceramic. The whole of the acoustic transducer 1a configured in this way is molded
with a synthetic resin or the like (not shown) and is electrically isolated from the medium M such
as surrounding water. The material of the mold is not limited to the synthetic resin, and the
material and thickness of the mold may be optimally set according to the required water pressure
resistance.
[0022]
Next, the operation of the acoustic transducer 1a according to the first embodiment will be
described. As shown in FIGS. 2 (a) and 2 (b), when the piezoelectric vibrator 8 receives a
predetermined applied voltage, displacement occurs to expand and contract. Since the
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piezoelectric vibrator 8 is bonded to the bending vibration plate 7, the bending vibration plate 7
generates a bending displacement due to the displacement of the piezoelectric vibrator 8. Then,
the channel 3 is displaced by displacement of the flexural diaphragm 7, and the first and second
acoustic radiation plates 5, 6 connected to the channel 3 are displaced. In addition, the third and
fourth acoustic radiation plates 5 a and 6 b disposed between the connecting members 4 are also
displaced in accordance with the displacement of the channel 3 transmitted through the
connecting members 4.
[0023]
The medium exclusion by the first and second acoustic radiation plates 5 and 6 will be described
with reference to the drawings. The adjacent first and second acoustic radiation plates 5 and 6
have a curved shape, respectively. The distance between the adjacent channels 3 increases, and
the curvature (flexure) of the curve decreases, and the adjacent channels are adjacent to each
other. As the space of 3 becomes smaller, the curvature (deflection) of the curve becomes larger.
Here, when the distance between the channels 3 in the first acoustic radiation plate 5 is
increased, the curvature of the curvature is reduced as shown in FIG. As the width narrows, as
shown in FIG. 2A, the curvature of the curve increases and the displacement of the medium
increases, resulting in an outward displacement. On the other hand, when the distance between
the channels 3 in the second acoustic radiation plate 6 increases, the curvature of the curvature
decreases and the displacement in the outward direction increases as shown in FIG. 2A, and the
distance between the channels 3 narrows. Then, as shown in FIG. 2 (b), the curvature of the
curvature increases and the displacement in the inward direction reduces the medium exclusion.
At this time, the third and fourth acoustic radiation plates 5a, 6b disposed between the
connecting members 4 are also displaced in accordance with the displacement of the channel 3
transmitted through the connecting members 4, and the first and second acoustic It will be
displaced in the same manner as the radiation plates 5 and 6.
[0024]
Adjacent bending vibration modules 9 have a bending position opposite to each other, and the
displacement position of the piezoelectric vibrator 8 and the polarization of the piezoelectric
vibrator 8 so that the displacements of the end portions on the channel 3 side approach and
move away respectively The direction and the connection direction of the lead wire connecting
the piezoelectric vibrator 8 are adjusted. For example, as shown in FIG. 3A, in the circumferential
direction centering on the shaft 2, the polarization directions of the adjacent piezoelectric
vibrators 8 are opposite to each other, and the piezoelectric vibrators 8 are bonded to the
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respective bending vibration plates 7. Change the face to be used alternately. Further, for
example, as shown in FIG. 3B, in the circumferential direction centering on the shaft 2, the
polarization directions of the adjacent piezoelectric vibrators 8 are opposite to each other, The
side to which the adhesive is attached is the same. Further, for example, as shown in FIG. 3C, in
the circumferential direction centering on the shaft 2, the polarization directions of the adjacent
piezoelectric vibrators 8 are made the same direction, and the piezoelectric vibrators 8 are
alternately connected. By arranging the piezoelectric vibrator 8 in this manner, two adjacent
bending diaphragms 7 are displaced apart, and when the distance between the channels 3
connected to the bending diaphragms 7 is increased, The bending diaphragm 7 is displaced so as
to approach the bending diaphragm 7 disposed next to the other, and the distance between the
channels 3 connected to the bending diaphragm 7 becomes narrow.
[0025]
Then, since the first and second acoustic radiation plates 5 and 6 are alternately disposed
between the adjacent channels 3, the application of the driving voltage causes the first and
second acoustic radiation plates 5 and 6 to The direction of medium removal may be the overall
outward media removal direction as shown in FIG. 2 or the overall inward media removal
direction shown in FIG. At this time, by arranging a plurality of bending vibration modules 9
having the same structure radially so as to be rotationally symmetrical with respect to the shaft
2, the balance of displacement can be maintained. And since this displacement is generated
repeatedly by the drive voltage, it becomes possible to radiate acoustic radiation uniformly
around the shaft 2. In addition, the first and second acoustic radiation plates 5 and 6 are set to
an optimal bending rate in consideration of the acoustic load and the like based on the frequency
to be used.
[0026]
At this time, the distance between the shaft 2 and the connecting member 4 becomes narrower
as it gets closer to the tip 2a of the shaft 2, thereby gradually changing the displacement of the
connecting member 4 and the third and fourth acoustic radiation plates 5a, 6b It is possible to
avoid the reduction of the displacement near the tip 2 a of the shaft 2. In addition, displacement
and bending of the first and second acoustic radiation plates 5 and 6 can be achieved by
matching the resonant frequency of the flexural vibration of the flexural vibration module 9 with
the resonant frequency of the first and second acoustic radiation plates 5 and 6. The
displacement of the diaphragm 7 can be superimposed, and the electroacoustic conversion
efficiency can be further improved. In addition, it is possible to further increase the
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electroacoustic conversion efficiency by adopting a structure in which the resonant frequencies
of the flexural vibration module 9 and the first and second acoustic radiation plates 5 and 6
match the acoustic frequency to be radiated, that is, the frequency of the driving voltage. it can.
[0027]
Next, the function and effect of the acoustic transducer according to the first embodiment will be
described using the drawings. The acoustic transducer 1a according to the first embodiment
includes alternately arranged first and third acoustic radiation plates 5, 5a curved outward and
second and fourth acoustic radiation plates 6, 6a curved inwardly. Because the acoustic emission
is performed by changing its curvature, the displacement can be expanded compared to a
conventional acoustic transducer using a planar acoustic radiation plate, a large acoustic
rejection volume can be secured, and low frequency There are effects that can realize acoustic
radiation. Further, by bonding the piezoelectric vibrator 8 to the bending vibration plate 7, the
bending vibration plate 7 vibrates in bending, so that the resonance frequency can be made
lower than the longitudinal vibration, and the output frequency can be lowered. In addition, since
the first and second acoustic radiation plates 5 and 6 are curved and they are alternately
arranged, and the curvature is changed to perform the medium elimination efficiently, the
piezoelectric vibrator 8 and the second There is no need to increase the shape of the first and
second acoustic radiation plates 5 and 6, and the weight of the acoustic transducer 1a can be
reduced.
[0028]
In addition, the first and second acoustic radiation plates 5 and 6 can be made of a synthetic
resin or a material containing a synthetic resin to be a member having a honeycomb structure by
being made lightweight and maintaining strength. The weight of the acoustic transducer 1a can
be reduced. Further, by making the channel 3 and the bending vibration plate 7 a synthetic resin
or a material containing a synthetic resin in a honeycomb structure or a laminated structure, it is
possible to make the member lightweight and secure in strength. Weight reduction. Needless to
say, other materials such as metal may be used for the first and second acoustic radiation plates
5 and 6, the bending diaphragm 7 and the channel 3.
[0029]
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Next, other embodiments will be described based on the attached drawings, but the same
reference numerals are used for the same or similar members and parts as the first embodiment
described above, and the description thereof is omitted. The configuration different from that of
the embodiment of FIG. As shown in FIG. 4, in the acoustic transducer 1 b according to the
second embodiment, the piezoelectric vibrators 18 are bonded to both sides of each of the
flexural diaphragms 17. The vibration module 19 is configured. At this time, the polarization
direction and the connection of the piezoelectric vibrator 18 are adjusted so that the
displacement directions of the flexural diaphragms 17 adjacent in the circumferential direction
centering on the shaft 12 become opposite directions. For example, as shown in FIG. Piezoelectric
vibrators with the same polarization direction are disposed on both sides of the flexural
diaphragm 17 so that the polarization directions of the piezoelectric vibrators 18 in the adjacent
flexural diaphragms 17 are reversed. Further, for example, as shown in FIG. 5B, the piezoelectric
vibrators 18 in the opposite polarization direction are disposed on both sides of the flexural
diaphragm 17, the connection directions of these piezoelectric vibrators 18 are reversed, and
they are adjacent to each other. In the bending diaphragm 17, the polarization direction of the
piezoelectric vibrator 18 is reversed.
[0030]
According to the acoustic transducer 1b according to the second embodiment, since the
piezoelectric vibrators 18 are bonded to both surfaces of the flexural diaphragm 17, the flexural
vibration of the flexural diaphragm 17 can be reliably flexed compared to the first embodiment.
It can be done.
[0031]
As shown in FIG. 6, the acoustic transducer 1c according to the third embodiment is disposed
radially around the shaft 22 instead of the flexural vibration module 9 according to the first
embodiment, and the shaft 22 and the channel And a piezoelectric vibrator stack 28 provided in
the vicinity of the shaft 2 between the adjacent displacement expansion plates 27.
The displacement magnifying plate 27 is formed of a synthetic resin or a material containing a
synthetic resin, and is a member having a honeycomb structure or a laminated structure. The
piezoelectric vibrator stack 28 has a structure in which plate-like piezoelectric vibrators are
stacked, and when one of the piezoelectric vibrator stacks 28 is expanded, the piezoelectric
vibrator stack 28 adjacent to the piezoelectric vibrator stack 28 is contracted Then, the polarities
of the connection lines of the piezoelectric vibrators constituting the piezoelectric vibrator stack
are alternately reversed, or the polarization directions of the piezoelectric vibrators are reversed,
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or the like. Then, the expanding piezoelectric vibrator stack 28 and the shrinking piezoelectric
vibrator stack 28 are alternately disposed between the displacement magnifying plates 27.
[0032]
When the piezoelectric vibrator stack 28 is displaced and expanded, the displacement
magnifying plate 27 connected to the both ends is displaced in the direction away from it. At this
time, since the piezoelectric vibrator stack 28 is disposed in the vicinity of the shaft 22, the end
of the displacement expansion plate 27 on the channel 23 side is displaced more than the
expansion and contraction of the piezoelectric vibrator stack 28, and the channel 23 is largely
displaced. It can be done. Then, by largely displacing the channel 23, the vibration of the
piezoelectric vibrator stack 28 is expanded and transmitted to the first and second acoustic
radiation plates 25, 26, and the first and second acoustic radiation plates 25, 26. The medium
can be displaced by largely changing its curvature, and the medium can be removed. Also, even
when the piezoelectric vibrator stack 28 is displaced and contracted, the displacement of the
piezoelectric vibrator stack 28 is expanded and transmitted to the first and second acoustic
radiation plates 25 and 26. At this time, by making the resonance frequency of the bending
vibration of the displacement expansion plate 27 coincide with the resonance frequency of the
first and second acoustic radiation plates 25, the electroacoustic conversion efficiency can be
further improved. In addition, the electroacoustic conversion efficiency can be further increased
by making the resonant frequencies of the displacement amplification plate 27 and the first and
second acoustic radiation plates 25 and 26 coincide with the acoustic frequency to be radiated,
ie, the frequency of the drive voltage. it can.
[0033]
According to the acoustic transducer 1c according to the third embodiment, the piezoelectric
vibrator stack 28 is provided in the vicinity of the shaft 22 of the displacement expanding plate
27, whereby the displacement of the piezoelectric vibrator stack 28 is expanded and the first and
The transmission to the second acoustic radiation plates 25, 26 makes it possible to increase the
medium rejection by the first and second acoustic radiation plates 25, 26 against the
displacement of the piezoelectric transducer stack 28.
[0034]
As shown in FIGS. 7A and 7B, in the acoustic transducer 1d according to the fourth embodiment,
end plates 41 are provided at both ends 32a of the shaft 32, and the connection according to the
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first embodiment is performed. The members are not provided.
A buffer 42 is provided between the end 33 a of the channel 33 and the ends 35 a and 35 b of
the first and second acoustic radiation plates 35 and 36 and the end plate 41. A gap d is
provided between the end plate 41 and the flexural vibration module 39. At this time, the
hardness and softness and thickness of the buffer material 42, and the material and thickness of
the mold are optimally set according to the required water pressure resistance. According to the
acoustic transducer 1d of the fourth embodiment, the same effect as that of the first embodiment
can be obtained.
[0035]
As shown in FIG. 8, in the acoustic transducer 1 e according to the fifth embodiment, the
coupling member according to the first embodiment and the end plate according to the fourth
embodiment are not provided, and the first and second acoustic radiation are provided. The
medium M is in contact with both surfaces of the plates 55 and 56. According to the fifth
embodiment, the tubular portion is constituted by the channel 53 and the first and second
acoustic radiation plates 55, 56, and the water column resonance of the water (medium M) inside
thereof is used, or A container provided with a small through-flow hole can be provided in the
inside of a cylinder part to make a Helmholtz resonance structure.
[0036]
As an application example of the present invention, it can be considered to use as a transmitter
that emits sound underwater or in the air.
[0037]
Although the embodiments of the acoustic transducer according to the present invention have
been described above, the present invention is not limited to the above-described embodiments,
and can be appropriately modified without departing from the scope of the present invention.
For example, in the embodiment described above, eight channels are arranged around the shaft,
but the number of channels may be other numbers. For example, in the embodiment described
above, the first and second acoustic radiation plates are formed of a synthetic resin or a material
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containing a synthetic resin, and this material is a member of a honeycomb structure, but is
formed of other materials May be In the above embodiment, the channel 3 and the bending
diaphragm 7 are formed of a synthetic resin or a material containing a synthetic resin, and are
members of a honeycomb structure or a laminated structure, but may be formed of other
materials. It does not have to be a member having a honeycomb structure or a laminated
structure. In the third embodiment described above, the displacement magnifying plate 27 is
formed of a synthetic resin or a material containing a synthetic resin to form a honeycomb
structure or a laminated structure, but may be formed of other materials, and the honeycomb
structure It does not have to be a laminated structure.
[0038]
1a, 1b, 1c, 1d, 1e acoustic transducers 2, 12, 22, 32 shafts (shaft members) 3, 13, 23, 33, 53
channel 4 connection members 5, 15, 25, 35, 55 first acoustic Radiation plate 5a third acoustic
radiation plate 6, 16, 26, 36, 56 second acoustic radiation plate 6a fourth acoustic radiation plate
7, 17 flexural diaphragm 8, 18 piezoelectric vibrator (vibrator) 41 end plate 42 cushioning
material d gap M medium
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