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JP2002345082

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DESCRIPTION JP2002345082
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
electroacoustic transducer for emitting a sound wave into water, and more particularly to a
bending transmission and reception wave which emits a sound wave into water by bending
vibration of a plurality of cylindrically arranged diaphragms. Related to
[0002]
2. Description of the Related Art Heretofore, in this type of bending transducer, cylindrical
vibrators are stacked as an electro-mechanical transducer, and an insulating sheath is provided
on the outer surface or the inner surface of the cylindrical vibrator, and lead wires are used. The
transmission frequency is set using the resonance by the respiratory vibration mode of the
cylindrical vibrator in order to obtain a high transmission sound pressure. However, this type of
transducer increases the resonance frequency in the respiratory vibration mode because the
rigidity of the cylindrical vibrator is high, and conversely, when trying to lower the resonance
frequency in the respiratory vibration mode, the outer diameter of the entire device Has the
disadvantage of becoming larger.
[0003]
For this reason, in order to obtain a small-sized, light-weight transducer with low frequency,
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deflection of the diaphragm is caused by the vertical vibration of the cylindrical vibrator and the
supporting force of the support ring that provides the fulcrum to the cylindrical vibrator. In
addition to causing resonance, it has been necessary to configure an acoustic tube in the
diaphragm inner surface space to retard the inner surface radiation sound wave of the
diaphragm and superimpose it on approximately the same phase and outer surface radiation
sound wave. That is, by making use of the flexural vibration modes of a plurality of diaphragms
provided in the axial direction of the cylindrical shape and lowering the resonance frequency of
this flexural vibration mode, the sound wave of the frequency can be reduced in size by a
lightweight flexible transducer. It is what you get.
[0004]
As an example of the above-described conventional example, there is a transmitter-receiver
(hereinafter referred to as a first conventional example) disclosed in, for example, Japanese
Patent Laid-Open No. 2-309799. The first conventional example will be described below. First,
the configuration of this conventional example will be described. FIG. 7 is a schematic view
showing the configuration of the above-described first conventional bending transducer. In this
example, for example, eight diaphragms 2 are arranged on the circumference of the cylindrical
vibrators 3a and 3b, and support rings are provided at upper and lower ends so as to fix the
eight diaphragms 2 arranged. 4a and 4b are provided, and the entire outer periphery is covered
with the outer sheet 1 and has a watertight protection structure. However, the sound waves
generated by the vibration of the diaphragm 2 are reversed in phase at the inner and outer
surfaces of the diaphragm 2 and the inner surface radiation sound wave is superimposed on the
outer surface radiation sound wave as it is. Resulting in. For this reason, in order to avoid this
short circuit phenomenon, it is comprised so that the phase of the internal surface radiation
sound wave of the vibrator ¦ oscillator 2 may be made to correspond to the phase of an external
surface radiation sound wave.
[0005]
Next, the operation of this conventional example will be described. FIG. 8 is a partial crosssectional view showing a part of the longitudinal cross-section of the above-mentioned first
conventional bending transducer. First, when an electrical signal having the same frequency as
the mechanical resonance frequency (fr) generated in the flexural vibration mode of the
diaphragm 2 is applied to the cylindrical vibrators 3a and 3b via the lead wires 5, the cylindrical
vibrators 3a and 3b are obtained. The radial vibration is generated, and the radial vibration
generates a bending vibration mode of the diaphragm 2 with the support rings 4a and 4b as a
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fulcrum. Low-frequency acoustic output can be obtained by mechanical resonance due to this
flexural vibration mode. The mechanical resonance frequency fr is such that the length of the
diaphragm 2 is L (cm) and the thickness is t (cm), the longitudinal elastic modulus is E (kg / cm
2), the density is ρ (kg / cm 3), the Poisson's ratio Assuming that α and the dimensionless
coefficient determined by the vibration system are σ, they are simply expressed by the following
equation. fr = απt / 2L2 {E / 3 (1-σ2) ρ} 1/2 (1) That is, the mechanical resonance frequency
fr is determined to one value depending on the material and size of the diaphragm 2 It is
[0006]
Therefore, in the first prior art device, although low-frequency acoustic radiation can be
performed with a small-sized, light-weight, bending-type transducer, as described above,
mechanical by the bending vibration mode of the diaphragm to be configured The resonant
frequency fr is determined to one value depending on the material and size of the diaphragm,
and the frequency band in which the transmission and reception level above a certain level can
be obtained is narrowed.
[0007]
Therefore, in order to obtain a low frequency as described above, in order to widen the frequency
band in which the transmission level above a certain level can be obtained, the cylindrical
vibrator performs respiratory vibration and applies a radial driving force to the dividing plate As
an example, there is an ultrasonic transducer described in JP-A-09-037379 and a method of
manufacturing the same (hereinafter referred to as a second conventional example).
In the second conventional example, in an annular or cylindrical piezoelectric vibrator made of
piezoelectric ceramic, a surface in which a group of holes is distributed in a plane which is in the
cylinder radial direction and which is perpendicular to the cylindrical axis direction. In the
surface of the cylindrical diameter of the piezoelectric vibrator, the piezoelectric vibrator is
formed at a plurality of positions at a pitch of 1/3 or less of the thickness. Such a pore group has
a function of reducing the Young's modulus of the piezoelectric vibrator and reducing the
coupling of the resonance modes other than in the thickness direction. When a high voltage is
applied to the inner and outer electrodes, the piezoelectric vibrator is But, it vibrates in thickness
in a torus shape polarized in the thickness direction, and radiates a cylindrical wave.
[0008]
However, even in the second prior art device described above, the pores of the piezoelectric
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ceramic are formed instead of the grooves, and the Young's modulus of the piezoelectric vibrator
is lowered by the pores. Since the cylindrical vibrator performs the breathing movement to
generate the radial driving force, it is necessary to pay close attention to the method of
manufacturing the piezoelectric ceramic, and the piezoelectric vibrator forming step, the firing
step, and the electrode There is a problem that the forming process and the manufacturing
method become very complicated, and furthermore, in order to manufacture the intended
transducer, a considerable size is required.
[0009]
The present invention has been made in view of the above-described circumstances, and utilizes
a bending vibration mode of a diaphragm which achieves small size and low frequency, and a
bending transmission and reception in which a predetermined or higher transmission level is
obtained in a wide frequency band. The purpose is to provide a waver.
[0010]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the invention
according to claim 1 is a cylindrical elastic body which is equally divided into a plurality in the
circumferential direction and separated in parallel in the axial direction. Provided at both axial
ends of a plurality of diaphragms arranged in the plurality of slits, a plurality of slits equally
dividing the plurality of diaphragms in the axial direction of the cylindrical shape, and the
plurality of diaphragms arranged in the cylindrical shape A plurality of cylindrical vibrators, a
lead wire connected to the cylindrical vibrators to give an electrical signal to the pair of
cylindrical vibrators, and an insulating sheath covering the entire cylindrical shape; Bending
vibration generated by bending the diaphragm in the cylindrical radial direction, and respiratory
vibration generated by moving the pair of cylindrical vibrators and the plurality of diaphragms in
the cylindrical radial direction. It is a bending transducer that emits sound waves into water by
resonance. Is formed between a pair of cylindrical vibrators and the insulating sheath, and is
formed of a circular plate having an outer diameter equal to the outer diameter of the pair of
cylindrical vibrators The pair of cylindrical vibrators includes a pair of plates having holes
through which the lead wires pass and a bolt and a nut for fixing the pair of plates such that the
distance between the pair of plates is constant. And in order to expand and contract the pair of
plates in the radial direction in accordance with the respiratory vibration of the plurality of
diaphragms, the pair of plates has relatively high rigidity in the thickness direction and relatively
low radial rigidity. It is characterized in that it is formed of a strength material.
[0011]
The invention according to claim 2 relates to the bending type transducer according to claim 1,
wherein the one-way strength material of the pair of plates makes the frequency of the sound
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wave by the respiratory vibration the frequency of the sound wave by the bending vibration. The
frequency of the sound wave by the respiratory vibration is superimposed on the frequency of
the sound wave by the flexural vibration to obtain a certain level of transmission and reception,
and it is possible to emit a sound wave of low mechanical resonance frequency in a wide
frequency band. There is.
[0012]
The invention according to claim 3 relates to the bending type transducer according to claim 1 or
2, wherein the pair of cylindrical vibrators has a central axis of a cylindrical array formed by the
plurality of diaphragms. It is characterized in that it is coaxial and has an outer periphery
substantially the same as the cylindrical array outer periphery of the plurality of diaphragms, and
an inner periphery smaller in diameter than the cylindrical array outer periphery of the plurality
of diaphragms.
[0013]
The invention according to claim 4 relates to the bending transducer according to claim 1 or 2,
wherein the pair of cylindrical vibrators has an outer diameter equal to the inner diameter of the
cylindrical array of the plurality of diaphragms. It is characterized in that it is provided between
the axial center and the both ends of the cylindrical array of the plurality of diaphragms.
[0014]
The invention according to claim 5 relates to the bendable transducer according to any one of
claims 1 to 4, wherein a bolt penetrates through a central portion of one of the pair of plates, It is
characterized in that the pair of plates is fixed by tightening a bolt with a nut arranged at the
center of the other plate.
[0015]
The invention according to claim 6 relates to the bendable transducer according to any one of
claims 1 to 5, and an elastic body is provided at the interface between the pair of plates and the
bolt and the nut. It is characterized by being filled and watertightly protected.
[0016]
The invention according to claim 7 relates to the bending type transducer according to claim 6,
characterized in that the elastic body is a synthetic resin.
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[0017]
The invention according to claim 8 relates to the bending type transducer according to any one
of claims 1 to 7, wherein the pair of cylindrical vibrators are arranged in a ring shape in the
circumferential direction. Active vibrator, a plurality of frequency adjusting members disposed
between the plurality of active vibrators, and a fiber material for clamping and fixing the outer
circumferences of the plurality of active vibrators and the plurality of frequency adjusting
members It is characterized by having a pair of composite cylindrical vibrators.
[0018]
The invention according to claim 9 relates to the bending transducer according to claim 8,
wherein each of the plurality of active vibrators is a cylinder or a prism.
[0019]
The invention according to claim 10 relates to a bending type transducer according to claim 8 or
9, wherein the breathing of the pair of composite cylindrical vibrators in the radial direction is
performed by adjusting the density of the frequency adjusting material. It is characterized by
adjusting the frequency of the sound wave by vibration.
[0020]
The invention according to claim 11 relates to the bending type transducer according to claim
10, wherein the frequency due to the respiratory vibration is lowered by increasing the density
of the frequency adjusting material, and the sound wave due to the bending vibration is It is
characterized by being close to the frequency.
[0021]
The invention according to claim 12 relates to the bending type transducer according to claim
11, wherein the frequency band of the sound wave due to the respiratory vibration and the
frequency band of the sound wave due to the bending vibration are superimposed to form a wide
resonant frequency band width. In the above, it is characterized in that a transmission level
above a certain level can be obtained.
[0022]
As described above, according to the first means of the present invention, the rigidity is strong in
the longitudinal direction of the cylindrical shape at the upper and lower end faces of the
bending transducer, and the one-way reinforcing material has low rigidity in the radial direction
of the cylindrical shape. And the plate is tightened and fixed by a bolt and a nut.
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[0023]
Further, according to the second means of the present invention, in the bending type transducer
having the first means, the cylindrical vibrating body is arranged in a circle of the active vibrating
body and the frequency adjusting material, and the outer periphery is wound with a fiber
material. A composite cylindrical vibrator formed in a cylindrical shape is used.
[0024]
In the first means, when the cylindrical vibrator generates the respiratory vibration mode due to
the circumferential expansion, the plate also performs the radial expansion following the
respiratory vibration mode of the cylindrical vibrator. It is possible to obtain a breathing
vibration mode of the entire cylindrical shape formed by the cylindrical vibrating body and the
diaphragm without interfering with the operation of the breathing vibration mode of the shaped
vibrating body.
Therefore, two resonance frequencies can be realized in combination with the resonance
frequency of the flexural vibration mode of the diaphragm generated by the longitudinal
vibration of the cylindrical vibrator.
Further, in the second means, the resonance frequency of the composite cylindrical oscillator in
the respiratory vibration mode can be lowered by the frequency adjusting member, and the
resonance frequency in the respiratory vibration mode is made closer to the resonance frequency
in the flexural vibration mode of the diaphragm. Can.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will
now be described in detail with reference to the drawings.
The description will be specifically made using an example.
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First, the configuration of the first embodiment of the present invention will be described.
FIG. 1 is a schematic view showing the configuration of a bending transducer according to a first
embodiment of the present invention.
In this example, the cylindrical elastic body is equally divided into a plurality in the
circumferential direction and the plurality of diaphragms 2 arranged in a cylindrical shape so as
to be separated in parallel in the axial direction and the plurality of diaphragms 2 A plurality of
slits 8 equally divided in the direction, a pair of cylindrical vibrating bodies 3a and 3b provided at
both axial ends of the plurality of diaphragms 2 arranged in a cylindrical shape, and a pair of
cylindrical vibrating bodies 3a and 3b In order to give an electrical signal to 3b, it comprises a
lead wire 5 connected to the cylindrical vibrators 3a, 3b, and an insulating sheath 1 covering the
whole of the cylindrical shape.
In particular, in this example, in particular, it is provided by bonding between the pair of
cylindrical vibrators 3a, 3b and the insulating sheath 1, and has a circular shape having the same
outer diameter as the outer diameter of the pair of cylindrical vibrators 3a, 3b. The pair of plates
40a and 40b are formed by a pair of plates 40a and 40b having holes for passing the lead wires
5 at predetermined positions and the distance between the pair of plates 40a and 40b is
constant. In order to expand and contract the pair of plates 40a and 40b in the radial direction
according to the respiratory vibration of the pair of cylindrical vibrating bodies 3a and 3b and
the plurality of diaphragms 2 including the bolt 6 and the nut 7 to be fixed, It is characterized in
that 40a and 40b are formed of a unidirectional strength material having high rigidity in the
thickness direction and low rigidity in the radial direction.
Thereby, bending vibration generated by bending the plurality of diaphragms 2 in the cylindrical
radial direction, and movement of the pair of cylindrical vibrators 3a and 3b and the plurality of
diaphragms 2 in the cylindrical radial direction It is a bending transducer that constitutes an
acoustic tube with the resulting respiratory vibration and emits sound waves into water.
[0026]
Next, the detailed configuration of each part of this example will be described.
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The plurality of diaphragms 2 are formed in a cylindrical shape by an elastic body such as metal
or synthetic resin, and divided substantially equally into a plurality by a plurality of slits 8
provided in parallel with the axial direction of the inner periphery of the cylindrical elastic body. ,
And are arranged separately from one another.
Further, the axial dimension of the cylindrical array of the plurality of diaphragms 2 is set
between approximately half wavelength and one wavelength of the sound wave, and the sonic
vibration can be emitted into water by the bending vibration of the plurality of diaphragms 2.
Also, although the plurality of diaphragms 2 are disposed here in a cylindrical shape (the cross
section is a circle), the shape may be flat (the cross section is a polygon), or the concape shape
(the cross), as necessary. The surface can be a concave wavy line or a convex shape (wave line
having a convex cross section).
Further, each of the plurality of diaphragms 2 is preferably equally divided into at least four.
Further, the plurality of slits 8 are provided between each of the plurality of diaphragms 2
arranged in a cylindrical shape to separate the plurality of diaphragms 2 from each other, and
when the plurality of diaphragms 2 vibrate, the diaphragms 2 are Are provided in parallel along
the axial direction of the inner circumference of the cylindrical elastic body so that they do not
contact.
Further, the pair of cylindrical vibrating bodies 3a and 3b are bonded to the upper and lower end
portions in the axial direction of the plurality of diaphragms 2, and are coaxial with the central
axis of the cylindrical array formed by the plurality of diaphragms 2 The outer periphery
substantially the same as the outer periphery of the cylindrical array of the diaphragm 2 and the
inner periphery smaller in diameter than the inner periphery of the cylindrical array of the
plurality of diaphragms 2 It can also be provided between them.
In this case, the inner periphery of the cylindrical array of the plurality of diaphragms 2 is equal
to the outer periphery of the cylindrical oscillators 3a and 3b.
The cylindrical vibrators 3a and 3b vibrate according to the input electric signal and transmit the
vibration to the plurality of diaphragms 2.
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[0027]
Further, the pair of plates 40a and 40b are provided by being bonded to both ends in the axial
direction of the cylindrical shape formed by the plurality of diaphragms 2 and the cylindrical
vibrators 3a and 3b, and the rigidity in the thickness direction is high in the radial direction. And
a hole for allowing the lead wire 5 to pass through. Further, the lead wire 2 supplies an electrical
signal from a part of one plate 40a to the cylindrical vibrating bodies 3a and 3b in order to
vibrate the cylindrical vibrating bodies 3a and 3b from the outside. The boundary surface
between the lead wire 5 and the pair of plates 40a and 40b is filled with an elastic body to be
watertightly protected. It is preferable to use a synthetic resin as the elastic body. Further, in the
bolt 6 and the nut 7, the bolt 6 passes through the central portion of one of the pair of plates 40a
and 40b, and the nut 7 is disposed at the other central portion. 40a and 40b are fixed, and the
entire cylindrical shape is clamped and fixed. Therefore, the distance between the pair of plates
40a and 40b is substantially constant. The bolt 6 and the nut 7 may be a simple shaft as long as
the pair of plates 40a and 40b can be fixed. An elastic body is filled in the interface between the
bolt 6 and the nut 7 and the pair of plates 40a and 40b, and watertight protection is provided. It
is preferable to use a synthetic resin as the elastic body. In addition, the insulating sheath 1 is an
adhesive around the cylindrical circle formed by the pair of plates 40a and 40b and the plurality
of diaphragms 2 in order to cover the plurality of diaphragms 2 and the pair of plates 40a and
40b. It is in close contact with In addition, since the gaps between the divided diaphragms 2 are
small, it is possible to obtain high water pressure resistance transmission / reception by
thickening the insulating sheath 1 appropriately.
[0028]
Next, the operation of this example will be described. First, the operation of the flexural vibration
mode in this example will be described. FIG. 2 is a schematic view showing the operation of the
flexural vibration mode in this example. The bending vibration mode is a mode in which the
cylindrical vibrating bodies 3a and 3b move in the axial direction of the cylindrical shape and the
plurality of diaphragms 2 bend. First, an electric signal is applied to the lead wire 5 from the
outside to excite the pair of cylindrical vibrating bodies 3a and 3b to generate mechanical
vibration. Since the plurality of diaphragms 2 and the pair of cylindrical vibrators 3a and 3b are
bonded and fixed, and the distance between the pair of plates 40a and 40b is restrained by the
bolt 6 and the nut 7, the pair of cylinders When the vibrators 3a and 3b longitudinally vibrate in
the axial direction by the above-described mechanical vibration, a pair of cylindrical vibrations
with the joint surface between the plurality of diaphragms 2 and the pair of cylindrical vibrators
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3a and 3b as a fulcrum Flexural vibration modes occur in the bodies 3a and 3b. At this time,
sound emission in the bending vibration mode is performed in the radial direction of the bending
transducer.
[0029]
Next, the operation of the respiratory vibration mode in this example will be described. FIG. 3 is a
schematic view showing the operation of the respiratory vibration mode in this example. The
respiratory vibration mode is a mode in which the cylindrical vibrators 3a and 3b move in the
cylindrical radial direction, and the cylindrical vibrators 3a and 3b and the plurality of
diaphragms 2 move in the radial direction together. First, when an electrical signal of a frequency
that excites the respiratory vibration mode of the pair of cylindrical vibration members 3a and 3b
is given, the pair of cylindrical vibration members 3a and 3b generates the respiratory vibration
mode. According to the respiratory vibration modes of the pair of cylindrical vibrators 3a and 3b,
the respiratory vibration modes of the entire cylindrical shape formed by the pair of cylindrical
vibrators 3a and 3b and the plurality of diaphragms 2 are excited. The resonance frequency in
this respiratory vibration mode is determined by the following equation depending on the shape
of the pair of cylindrical vibrating bodies 3a and 3b. fr ′ = (1 / 2πa) × (E / ρ) 1/2 (2) where a:
average radius of the cylindrical vibrators 3a and 3b, E: longitudinal length of the cylindrical
vibrators 3a and 3b Elastic modulus, 、: density of cylindrical vibrators 3a and 3b. At this time,
since the rigidity in the radial direction of the pair of plates 40a and 40b is set to be sufficiently
weaker than the respiratory vibration mode generation force of the pair of cylindrical vibrators
3a and 3b, the pair of cylindrical vibrators The pair of plates 40a and 40b also expand and
contract in the radial direction in accordance with the respiratory vibration mode 3a and 3b.
Therefore, the pair of plates 40a and 40b does not disturb the amplitude of the pair of cylindrical
vibrators 3a and 3b due to the respiratory vibration mode. Thus, in this example, in addition to
the first mode by the flexural vibration mode of the diaphragm 2, the second by the respiratory
vibration of the entire cylindrical shape by the pair of cylindrical vibrators 3a and 3b and the
plurality of diaphragms 2. Modes can be obtained at close frequencies. Therefore, using the
bending vibration modes of the plurality of diaphragms 2 and the respiration vibration modes of
the cylindrical vibrators 3a and 3b and the plurality of diaphragms 2 to widen the frequency
band in which sound waves of low mechanical resonance frequency can be emitted. Can.
[0030]
As described above, in this example, when the pair of cylindrical vibrators 3a and 3b generate
the respiratory vibration mode due to the circumferential extension, the pair of plates 40a and
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40b are also the pair of cylindrical vibrators 3a and 3b. In order to follow the respiratory
vibration mode and to expand the diameter, the pair of cylindrical vibrators 3a and 3b and the
plurality of diaphragms 2 do not prevent the operation of the respiratory vibration mode of the
pair of cylindrical vibrators 3a and 3b. The respiration vibration mode of the whole cylindrical
shape to form can be obtained. Therefore, the resonance frequency fr 'in the respiratory vibration
mode shown in FIG. 3 is the resonance frequency fr in the bending vibration mode of the
plurality of diaphragms 2 by the longitudinal vibration of the pair of cylindrical vibrating bodies
3a and 3b as shown in FIG. Together with this, two resonance frequencies are continuous, and a
certain level or more of transmission / reception levels can be obtained in a wide frequency band.
[0031]
Second Embodiment Next, a second embodiment of the present invention will be described. First,
the configuration of the second embodiment of the present invention will be described. FIG. 4 is a
schematic view showing the configuration of a composite cylindrical diaphragm according to this
example. In the first embodiment described above, the pair of cylindrical vibrators 3a and 3b are
used as drive sources for vibrational excitation, but in this example, instead of the pair of
cylindrical vibrators 3a and 3b, a pair of composite cylinders is used. The vibrator 50 is used.
Therefore, in this example, the cylindrical elastic body is equally divided into a plurality in the
circumferential direction, and the plurality of diaphragms 2 and the plurality of diaphragms 2
arranged in a cylindrical shape are separated in parallel in the axial direction. A plurality of slits
8 equally divided in the axial direction, a pair of composite cylindrical vibrators 50 provided at
both axial ends of the plurality of diaphragms 2 arranged in a cylindrical shape, and a pair of
composite cylindrical vibrators 50 includes a lead wire 5 connected to the composite cylindrical
vibrating body 50 to give an electrical signal to 50, and an insulating sheath 1 covering the
entire cylindrical shape, and a pair of the composite cylindrical vibrating body 50 and the
insulating sheath 1 A pair of plates 40a, which are formed between circular plates having an
outer diameter equal to the outer diameter of the pair of composite cylindrical vibrators 50, and
provided with holes through which the lead wires 5 penetrate at predetermined positions. 40b
and the distance between the pair of plates 40a and 40b are constant So as to fix the pair of
plates 40a and 40b, and the diameter of the pair of plates 40a and 40b in accordance with the
respiratory vibration of the pair of composite cylindrical vibrators 50 and the plurality of
diaphragms 2. In order to expand and contract in the direction, the pair of plates 40a and 40b is
formed of a unidirectional strength material having high rigidity in the thickness direction and
low rigidity in the radial direction. In particular, the composite cylindrical vibrating body 50 used
in this example includes a plurality of active vibrating bodies 9 arranged in a ring shape in the
circumferential direction, and a frequency adjusting member 20 disposed between the plurality
of active vibrating bodies 9. They are arranged in a circle, and the entire periphery is clamped
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and fixed by the fiber material 10. The plurality of active vibrators 9 are rectangular when
viewed from the top, and arranged in a ring when arranged in a ring in the circumferential
direction. The frequency adjustment member 20 is disposed between the plurality of active
vibrators 9 and can change the density of the entire composite cylindrical vibrator 50 by
changing its density to change the resonant frequency of the composite cylindrical vibrator 50.
The fiber material 10 clamps and fixes the outer circumferences of the plurality of active
vibrators 9 and the plurality of frequency adjustment members 20. Thereby, bending vibration
generated by bending the plurality of diaphragms 2 in the cylindrical radial direction, and
movement of the pair of composite cylindrical vibrators 50 and the plurality of diaphragms 2 in
the cylindrical radial direction are generated. It is a bending transducer that composes an
acoustic tube by respiratory vibration and radiates sound into water.
[0032]
Next, the operation of this example will be described. First, the bending vibration mode in this
example will be described. An electrical signal is externally applied to the lead wire 5 to excite
the pair of composite cylindrical vibrators 50 to generate mechanical vibration. The plurality of
diaphragms 2 and the pair of composite cylindrical vibrators 50 are bonded and fixed, and the
distance between the pair of plates 40 a and 40 b is restrained by the bolt 6 and the nut 7. When
the vibrating body 50 longitudinally vibrates due to the above-described mechanical vibration,
bending vibration is generated in the pair of composite cylindrical vibrating bodies 50 with the
bonding surface of the plurality of diaphragms 2 and the pair of composite cylindrical vibrating
bodies 50 as a fulcrum. A mode occurs. At this time, sound emission in the bending vibration
mode is performed in the radial direction of the bending transducer.
[0033]
Next, the operation of the respiratory vibration mode in this example will be described. First,
when an electrical signal of a frequency that excites the respiratory vibration mode of the pair of
composite cylindrical vibrators 50 is given, the pair of composite cylindrical vibrators 50
generate the respiratory vibration mode. In accordance with the respiratory vibration modes of
the pair of composite cylindrical vibrators 50, respiratory vibration modes of the entire
cylindrical shape formed by the pair of composite cylindrical vibrators 50 and the plurality of
diaphragms 2 are excited. The resonance frequency according to this respiratory vibration mode
is obtained by the above-mentioned equation (2). Here, the density of the frequency adjusting
material 20 of the composite cylindrical vibrating body 50 is increased, and ρ (density) of the
composite cylindrical vibrating body 50 as a whole is increased. Thus, 密度 (density) is adjusted,
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and the resonance frequency fr ′ in the cylindrical respiratory vibration mode obtained by the
equation (2) is brought close to the resonance frequency fr in the flexural vibration mode of the
diaphragm 2. As the resonance frequencies fr and fr 'of the two mechanical resonance modes are
brought closer, the two frequency bands overlap, and the frequency band width at which a
certain level or more can be obtained can be expanded. The adjustment of the density of the
frequency adjusting material 20 can be adjusted by changing the material.
[0034]
As described above, in the second embodiment of the present invention, by changing the density
of the frequency adjustment member 20, it is possible to lower the resonance frequency fr ′ in
the respiratory vibration mode of the composite cylindrical vibrator 50, and the bending of the
diaphragm 2 It can be close to the resonance frequency fr due to the vibration mode.
[0035]
FIG. 5 is a graph showing transmission level-frequency characteristics of the bending transducer
according to an embodiment of the present invention.
The solid line shows the transmission level-frequency characteristic according to the
conventional example, and the dotted line shows the transmission level-frequency characteristic
according to the present invention. As for this transmission level-frequency characteristic, in the
conventional example shown by the solid line in FIG. 5, the frequency at which the transmission
level above a certain level can be obtained is only the resonance frequency fr in the bending
vibration mode. With two resonance frequencies, ie, the resonance frequency fr in the bending
vibration mode of the diaphragm 2 shown in FIG. 2 and the resonance frequency fr ′ in the
cylindrical breathing vibration mode shown in FIG. Two frequency bands in which transmission
levels can be obtained are obtained.
[0036]
Similar to FIG. 5, FIG. 6 is a graph showing transmission level-frequency characteristics of the
bending transducer according to the embodiment of the present invention, but two frequencies
are closer to each other as compared with FIG. It is a graph of time. As the diameter of the
cylindrical shape of the cylindrical vibrator 2 is increased, the resonance frequency fr ′ in the
respiratory vibration mode decreases from the equation (2), and the resonance frequency fr in
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the flexural vibration mode approaches the two resonances. As the frequencies fr and fr ′
approach each other, the two frequency bands overlap and, as shown in FIG. 6, the frequency
bandwidth in which the transmission level above a certain level can be obtained widens. In FIG. 6,
this transmission level above a certain level is shown as the "required level". That is, FIG. 6 shows
that the resonance frequency fr in the bending vibration mode and the resonance frequency fr 'in
the respiration vibration mode are continuously transmission levels of values above the required
level.
[0037]
As mentioned above, although the embodiment of the present invention has been described in
detail, the specific configuration is not limited to this embodiment, and any change in design or
the like without departing from the spirit of the present invention is included in the present
invention. For example, although the plurality of diaphragms 2 are arranged in a cylindrical
shape in the embodiment described above, the present invention is not limited to this, and may
be arranged in a polygonal shape as needed.
[0038]
In the above-described embodiment, the cross section of the cylindrical diaphragm 2 may be flat,
concave, or convex, if necessary. However, the present invention is not limited to this. Or a
random shape.
[0039]
Further, in the above-described embodiment, the active vibrator 9 of the composite cylindrical
vibrator 50 and the periphery of the frequency adjustment member 20 are clamped and fixed by
the fiber material 10, but the present invention is not limited thereto. Other components may be
added as 50.
[0040]
Further, in the above-described embodiment, the active vibrating body 9 of the composite
cylindrical vibrating body 50 is rectangular, but the present invention is not limited to this. And
other shapes may be used.
[0041]
Further, in the embodiment described above, the fiber material 10 of the composite cylindrical
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vibrating body 50 may be made of not only fibers but also other materials, for example, an elastic
body made of synthetic resin.
[0042]
Further, in the embodiment described above, the boundary between the pair of plates 40a and
40b and the bolt 6 or the nut 7 is filled with a synthetic resin to be watertightly protected, but
the invention is not limited thereto. You may comprise by materials other than a synthetic resin.
[0043]
As described above, according to the configuration of the present invention, in addition to the
first mode according to the flexural vibration mode of the diaphragm, the pair of cylindrical
vibrators (or composite cylindrical vibrators) and the vibrations are provided. Since the second
mode due to the respiratory vibration of the entire cylindrical shape due to the plate can be
obtained at a close frequency, a low mechanical resonance frequency is obtained using bending
vibration modes of multiple diaphragms and respiratory vibration modes of the cylinder It is
possible to widen the frequency band of a bendable transducer that can emit sound waves.
[0044]
Brief description of the drawings
[0045]
1 is a schematic view showing the configuration of a bending transducer according to a first
embodiment of the present invention.
[0046]
2 is a schematic view showing the operation (bending vibration mode) of the bending transducer
according to the first embodiment of the present invention.
[0047]
3 is a schematic view showing the operation (respiratory vibration mode) of the bending
transducer according to the first embodiment of the present invention.
[0048]
4 is a schematic view showing the structure of a composite cylindrical oscillator according to a
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bending transducer according to a second embodiment of the present invention.
[0049]
5 is a graph showing an example of the transmission level frequency characteristics of the
bending transducer according to an embodiment of the present invention.
[0050]
6 is a graph showing an example of the transmission level frequency characteristics of the
bending transducer according to an embodiment of the present invention.
[0051]
7 is a schematic view showing the configuration of a conventional bending transducer.
[0052]
8 is a schematic view showing the operation of the conventional bending transducer.
[0053]
Explanation of sign
[0054]
DESCRIPTION OF SYMBOLS 1 insulation sheath 2 diaphragm 2a bending vibration mode 2b
respiratory vibration mode 3a, 3b cylindrical vibrating body 4a, 4b support ring (conventional
example) 5 lead wire 6 bolt 7 nut 8 slit 9 active vibrating body 10 fiber material 20 frequency
adjusting material 40a, 40b plate 50 composite cylindrical vibrator
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