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JPH104598

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JPH104598
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
resonant frequency variable transducer, and more particularly to a resonant frequency variable
transceiver capable of emitting a sound wave into water by resonating a medium in a cylinder
and varying the resonant frequency. Related to
[0002]
2. Description of the Related Art Conventionally, a cylindrical transducer which is installed in
water and used as a sound source is known. Generally, this utilizes the resonance of the medium
in the cylindrical oscillator, that is, the water column resonance, For example, as shown in the
cross-sectional view of FIG. 6, a cylindrical piezoelectric vibrator 2 whose inner and outer
peripheral surfaces and end faces are covered by a sheath 1 to have a waterproof structure is
provided. Media such as water and sea water from the
[0003]
As shown in the perspective view of FIG. 7, the cylindrical piezoelectric vibrator 2 is provided
with electrodes 8 a and 8 b on the inner and outer peripheral surfaces of the hollow cylindrical
piezoelectric material 7, and the following equation fr = c / (between the electrodes 8 a and 8 b
πd) (1) (where c: sound velocity, d: average diameter of the piezoelectric material 7) When an
electrical signal of the mechanical resonance frequency fr according to the breathing mode
represented by the reed 6 is supplied, the mechanical material of the piezoelectric material 7 It is
the composition which can obtain a high efficiency sound output by the specific resonance.
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[0004]
On the other hand, in addition to the mechanical resonance frequency fr, the cylindrical
piezoelectric vibrator 2 has an acoustic resonance frequency FR according to the following
equation due to the water column inside the cylindrical piezoelectric vibrator 2.
[0005]
FR = α1 × (A−A2−α2) / (4π) (2) where A = α3 × (L / (2R)) + α4, and R is a cylindrical
piezoelectric vibrator 2 (piezoelectric material 7 Is the coefficient determined by the sound
velocity and elastic modulus of the medium flowing into the hollow portion of the cylindrical
piezoelectric vibrator 2 (piezoelectric material 7), and further by the inner radius R and elastic
modulus, and α2, α3 and α4 are L is a correction coefficient of the cylindrical end, and L is a
length of the cylindrical piezoelectric vibrator 2 in the axial direction.
[0006]
If an electrical signal of the acoustic resonance frequency FR due to the water column is supplied
between the electrodes 8a and 8b via the lead 6, an acoustic output with high efficiency as in the
mechanical resonance of the piezoelectric material 7 can be obtained.
[0007]
Here, if the resonance frequency of the cylindrical piezoelectric vibrator 2 is fixed, the efficient
frequency band is fixed in the vicinity of the resonance point, and water or seawater which is a
medium inside the cylindrical piezoelectric vibrator 2 Due to changes in the speed of sound of
the medium due to changes in water temperature and water depth, there is a disadvantage that
the resonance frequency fluctuates.
[0008]
In view of the above, there is conventionally known a transmitter-receiver which can make the
above-mentioned resonance frequency variable (Japanese Patent Laid-Open Nos. 2-305094, 3113386).
As this conventional resonant frequency variable transducer, as shown in FIG. 8, for example,
three cylindrical piezoelectric vibrators 2a, 2b and 2c are coaxially laminated, and the cylindrical
piezoelectric vibrator 2a, A configuration is known in which the resonant frequency is varied by
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apparently varying the axial length L of the cylindrical piezoelectric vibrator by adjusting the
arrangement interval of 2b and 2c with the interval adjustment mechanism (not shown). .
[0009]
As another conventional resonant frequency variable transducer, as shown in FIG. 9, the inner
surface is in close contact with the outer surface of the cylindrical piezoelectric vibrator 2a, and
the axial direction of the cylindrical piezoelectric vibrator 2a. The hollow cylindrical metal
cylinders 9a and 9b having a movable structure are provided respectively, and the axial length L
of the cylindrical piezoelectric vibrator 2a is substantially varied by adjusting the positions of the
metal cylinders 9a and 9b. There is known a configuration in which the resonance frequency is
variable.
[0010]
However, in the conventional transducer shown in FIG. 8, the axial length of the apparent
cylindrical shape is increased as the arrangement interval of the cylindrical piezoelectric
vibrators 2a, 2b and 2c is lengthened. As the water column resonance can be made to have a low
frequency, the distance between the cylindrical piezoelectric vibrators 2a, 2b and 2c is increased,
so that the density of the medium such as water or seawater in the cylindrical hollow portion
does not increase. There is a disadvantage that the frequency selectivity drops sharply and the
transmission voltage sensitivity drops significantly.
[0011]
Further, although the conventional transducer shown in FIG. 9 is configured to vary the axial
length of the cylindrical transducer, there is a limit in the range in which the length can be varied
mechanically, and the frequency variable range is There is a disadvantage that only one octave or
less can be obtained.
[0012]
The present invention has been made in view of the above points, and it is an object of the
present invention to provide a resonant frequency variable transmitter-receiver capable of
setting the variable range of frequency to one or more octaves while maintaining the frequency
selectivity of water column resonance.
[0013]
[Means for Solving the Problems] In order to achieve the above object, the present invention
resonates a water column in a hollow cylinder of a hollow cylindrical cylindrical vibrator whose
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inner and outer periphery is made waterproof by a sheath. In the transducer for emitting sound
waves in water, the transducer is provided on both axial end faces of the cylindrical piezoelectric
vibrator, has one or more notches, and the hollow cylinder is cylindrical piezoelectric. The hollow
cylindrical first and second inner cylinders communicating with the hollow cylinder of the
vibrator, and the first and second inner cylinders are covered with the hollow cylindrical portion,
and one or more notches are provided. And the hollow cylinder has hollow cylindrical first and
second outer cylinders communicating with the hollow cylinder of the cylindrical piezoelectric
vibrator, the first inner cylinder and the first outer cylinder, and At least one of the two cylinders
is a circle between the two inner cylinders and the second outer cylinder. It is obtained by
rotatably the directions.
[0014]
Thereby, in the present invention, at least one of the first inner cylinder and the first outer
cylinder and the second inner cylinder and the second outer cylinder rotate in the circumferential
direction. Thus, since the area of the notches overlapping between the inner cylinder and the
outer cylinder, that is, the opening area of the notches can be changed, the cylindrical
piezoelectric vibrator is formed of the first inner cylinder and the first outer cylinder. The axial
length of the entire transducer to the second inner cylinder and the second outer cylinder can be
equivalently changed by the circumferential rotation described above.
[0015]
The cylindrical piezoelectric vibrator according to the present invention is characterized by
comprising a plurality of piezoelectric vibrators coaxially arranged and adhered to each other,
and adjacent cylindrical piezoelectric vibrators are electrically connected to each other by a
strap. I assume.
Therefore, in the present invention, the intervals between the plurality of cylindrical piezoelectric
vibrators are always constant.
[0016]
DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention
will be described with reference to the drawings.
[0017]
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FIG. 1 is a partially cutaway longitudinal sectional view of an embodiment of a resonant
frequency variable transducer according to the present invention, and FIG. 2 is an exploded
perspective view of a partial cross section of FIG.
In both figures, the same components are given the same reference numerals, and the same
components as FIG. 8 are given the same reference numerals.
[0018]
The resonance frequency variable transducer of this embodiment includes three cylindrical
piezoelectric vibrators 2 as shown by 2a, 2b and 2c.
The cylindrical piezoelectric vibrators 2a, 2b and 2c are electrically connected to each other by
the strap 5, connected to leads (not shown), and coaxially disposed and adhesively fixed to each
other. One communicating hollow portion is formed by the vibrators 2a, 2b and 2c.
[0019]
The axial length, diameter, etc. of the cylindrical shape of the cylindrical piezoelectric vibrators
2a, 2b and 2c forming the hollow portion are adjusted to a desired frequency.
The inner and outer peripheries of the cylindrical piezoelectric vibrators 2a, 2b and 2c and a part
of the leads are molded with a sheath 1 made of a resin such as urethane to form a watertight
structure.
[0020]
Of the cylindrical piezoelectric vibrators 2a, 2b and 2c molded on the inner and outer
peripheries, the end portions of the cylindrical piezoelectric vibrators 2a and 2c located at both
axial ends have large diameters of notched inner cylinders 3a and 3b. The bottoms are
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respectively adhesively fixed.
The notched inner cylinders 3a and 3b are hollow cylindrical members made of aluminum each
having a ridge at the bottom, and V-shaped notched portion 31a, which becomes thinner toward
the side of the cylindrical piezoelectric vibrators 2a and 2c on its side, 31 b is provided, and its
hollow cylindrical portion is in communication with the hollow cylinders of the cylindrical
piezoelectric vibrators 2 a and 2 c.
[0021]
The notched outer cylinders 4a and 4b are attached to the outer sides of the notched inner
cylinders 3a and 3b so as to be rotatable in the circumferential direction.
That is, the notched outer cylinder 4a, 4b accommodates the notched inner cylinder 3a, 3b in its
hollow cylindrical portion and is mounted so as to be circumferentially rotatable, and the hollow
cylindrical portion is cylindrical It is in communication with the hollow cylinders of the
piezoelectric vibrators 2a and 2c.
[0022]
The notched outer cylinders 4a and 4b are hollow cylindrical members made of aluminum, and
the diameter (inner diameter) of the inner side surface is set to a value slightly larger than the
outer diameter of the notched inner cylinders 3a and 3b, V-shaped notch portions 41a and 41b
are provided on the side surfaces thereof so as to be thinner toward the cylindrical piezoelectric
vibrators 2a and 2c.
The axial length, diameter, etc. of the entire cylindrical shape including the above notched inner
cylinder 3a, 3b and the notched outer cylinder 4a, 4b are set to meet the desired minimum
acoustic resonance frequency, for example, It is about 20 cm.
[0023]
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Next, the operation of this embodiment will be described.
When a voltage is applied to the cylindrical piezoelectric vibrators 2a, 2b and 2c, the cylindrical
piezoelectric vibrators 2a, 2b and 2c vibrate by respiration, and due to water column resonance,
the cylindrical piezoelectric vibrators 2a, 2b and 2c and the notched inner cylinder In one
cylindrical tube consisting of 3a and 3b, a vibration wave shown by an alternate long and short
dash line in FIG. 3 is generated such that both ends of the cylinder are antinodes of vibration.
[0024]
Here, when the notches 31a, 31b, 41a and 41b of the notched inner cylinders 3a, 3b and the
notched outer cylinders 4a, 4b are closed, the notched inner cylinders 3a, 3b and the notched
outer cylinders 4a, 4b The axial length of the entire cylindrical shape of the entire transducer of
this embodiment including this is L1 of the maximum value as shown in FIG. 3, and the water
column resonance frequency (acoustic resonance frequency) at this time is 5 is the lowest
acoustic resonance frequency shown by f1.
The acoustic resonance frequency f1 is determined by the equation (2).
However, in this case, FR = f1 and A = α3 × (L1 / (2R)) + α4, and R is the inner radius of the
notch inner cylinder 3a, 3b.
[0025]
From this state, when the notched outer cylinders 4a and 4b are rotated in the circumferential
direction, the notches 41a and 41b overlap with the notches 31a and 31b of the notched inner
cylinders 3a and 3b, ie, The area of the opening to the outside gradually increases, and as a
result, the axial length of the cylindrical shape of the entire transducer becomes equivalently
shorter.
[0026]
Then, when the notches 41a and 41b and the notches 31a and 31b completely overlap and the
opening area to the outside is maximized, as shown in FIG. The vibration wave shown by the
alternate long and short dash line in FIG. 4 has the length equivalent to the minimum value L2
and in this case the two ends of one cylinder consisting of the cylindrical piezoelectric vibrators
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2a, 2b and 2c are antinodes of vibration. As the water column resonance frequency (acoustic
resonance frequency) is generated, the highest acoustic resonance frequency shown by f2 in FIG.
5 is obtained.
[0027]
Thus, in this embodiment, the water column resonance frequency (acoustic resonance frequency)
is in the range from f1 to f2 according to the opening area where the notches 41a and 41b and
the notches 31a and 31b overlap. The variable frequency range can be obtained by setting the
aperture area to one or more octaves.
[0028]
According to this embodiment, a single configuration can cope with almost all applications in
which transducers of a plurality of types of lengths are manufactured according to the
conventional application.
Further, in this embodiment, since the intervals between the cylindrical piezoelectric vibrators 2a
to 2c are always constant, the transmission voltage sensitivity is largely different as in the
conventional variable resonance frequency transducer shown in FIG. It is possible to prevent the
decrease.
[0029]
The present invention is not limited to the above embodiment. For example, the configuration in
which the rotation of the notched outer cylinders 4a and 4b in the circumferential direction is
rotated by a desired rotation angle motor according to an instruction from the outside by radio
or the like. Alternatively, the resonant frequency of the transducer can be varied even after
installation in water or in the sea.
[0030]
In the embodiment shown in FIGS. 1 and 2, the notched outer cylinders 4a and 4b are configured
to be rotatable in the circumferential direction, but one or both of the notched inner cylinders 3a
and 3b can be rotated. It is good also as composition.
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In addition, the shape of the notch is not limited to the V shape, and may be another shape, and
the notch has two positions in each of the notch inner cylinder 3a, 3b and the notch outer
cylinder 4a, 4b. The above may be provided.
Furthermore, although it has been described that three cylindrical piezoelectric vibrators are
arranged coaxially, the number of cylindrical piezoelectric vibrators may be plural other than
this, or the present invention can be applied with only one single piezoelectric vibrator. .
[0031]
As described above, according to the present invention, the first inner cylinder and the first outer
cylinder, and the notches overlapping respectively between the second inner cylinder and the
second outer cylinder. By changing the area of the portion, that is, the opening area of the
medium such as water, seawater, etc. of the notch portion to the outside, the second inner
cylinder and the first outer cylinder are connected via the cylindrical piezoelectric vibrator Since
the axial length of the entire transducer to the inner cylinder and the second outer cylinder can
be equivalently changed by the circumferential rotation of the inner cylinder or the outer
cylinder, the water column resonance The frequency can be varied, and thus the resonant
frequency can be varied significantly over a frequency range of one or more octaves, while
maintaining a high efficiency acoustic output of the water column resonance with a single
transducer.
[0032]
Further, according to the present invention, even when a plurality of cylindrical piezoelectric
vibrators are provided, the distance between the cylindrical piezoelectric vibrators is constant, so
that the selectivity of the water column resonance frequency can be maintained. A significant
drop in transmission voltage sensitivity can be prevented.
[0033]
Brief description of the drawings
[0034]
1 is a partially cut vertical sectional view of an embodiment of the present invention.
[0035]
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2 is a partial cross-sectional exploded perspective view of FIG.
[0036]
3 is a principle explanatory view of the water column resonance time (minimum frequency) of
the embodiment of the present invention.
[0037]
4 is a principle explanatory view of the water column resonance time (maximum frequency) of
the embodiment of the present invention.
[0038]
5 is a characteristic diagram of an embodiment of the present invention.
[0039]
6 is a cross-sectional view of a conventional example.
[0040]
7 is a perspective view of the main part of FIG.
[0041]
<Figure 8> It is the strabismus figure which shows the outline of the principal part of one
example of former resonance frequency variable transducer.
[0042]
<Figure 9> It is the strabismus figure which shows the outline of the principal part of the other
example of the former resonance frequency variable transducer.
[0043]
Explanation of sign
[0044]
DESCRIPTION OF SYMBOLS 1 Sheath 2, 2a, 2b, 2c Cylindrical piezoelectric vibrator 3a, 3b Notch
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inner cylinder 4a, 4b Notch outer cylinder 5 Strap 31a, 31b Notch inner cylinder notch 41a, 41b
Notch outer cylinder cut Notch
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