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JPH10304488

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DESCRIPTION JPH10304488
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
cylindrical cardioid hydrophone having cardioid directivity for receiving a sound wave from a
predetermined direction, and as an underwater acoustic apparatus, for example, a wave receiving
sensor of Toei Sonar or Sonobuoy It relates to a cylindrical cardioid hydrophone which can be
used as
[0002]
2. Description of the Related Art In order to obtain cardioid directivity using three wave reception
sensors, for example, three nondirectional wave reception sensors are linearly arranged, and the
wave reception sensor outputs at both ends having equal wave reception sensitivity When E1
and E2 are connected in reverse phase in parallel, it becomes a pressure gradient type, and its
output E3 is expressed by equation (1).
[0003]
A composite in which the above output is shifted in phase by π / 2 and an electronic circuit
section for equalizing the sensitivity of the wave receiving sensor is connected in series or in
parallel with the non-directional wave receiving sensor arranged in the center. It can be obtained
by the output.
[0004]
That is, in the case of kd · sin θ / 2 << 1 in equation (1)
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1
[0005]
K = 2π / λ (λ: wavelength of sound wave)
[0006]
The directivity of the centrally located receiving sensor
[0007]
Then, the combined sum of the outputs of the three received wave sensors is expressed by
equation (3).
[0008]
In order for this to be the cardioid directivity characteristic "A (1 + cos θ)", it is necessary to set
A = A0 kd, φ = ± jπ / 2.
[0009]
That is, if the output is matched with the value in the linear arrangement direction, which is the
maximum output of the pressure gradient type, and the phase is shifted by π / 2, cardioid
directivity can be obtained by their combined sum.
[0010]
By the way, when cardioid directivity is obtained as described above, the wave receiving sensors
are arranged on the base at the required intervals, and a cylindrical piezoelectric ceramic vibrator
is used as the wave receiving sensor. When the cardioid hydrophone is configured, the directivity
pattern may be disturbed due to the influence of the sound wave superposition due to the
reflection of the incident sound wave between the base and the wave receiving sensor.
[0011]
Moreover, not only the structure becomes complicated, but in such a structure, complex
resonance is generated in the entire assembly of the array configuration of cylindrical
piezoelectric ceramic vibrators, and it is extremely preferable by superposing on the acoustic
signal. It becomes a hydrophone with no frequency characteristic, which also disturbs the
directivity pattern.
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[0012]
In addition, in the case of having resonance characteristics due to vibration of the entire
assembly unit, the characteristics significantly change depending on the water temperature or
water pressure, so that complicated and fine calculation work occurs together with extra
measurement work for each correction of the measurement.
In addition, it is difficult to separate composite influences into individual factors, it is also difficult
to make accurate corrections, and it can not be denied that the effects on the deterioration of
measurement accuracy can be made.
[0013]
By the way, when producing a hydrophone by said arrangement configuration, according to the
conventional method, the material of each part of a hydrophone is a boot made of synthetic
rubber or a synthetic resin, a cap, a rubber seat, and titanium zirconate type porcelain vibrator
The other components such as are mainly brass and an aluminum alloy, and therefore relatively
heavy.
[0014]
Along with that, it is necessary to use a thick cable that is strong, and the weight increase, and it
takes more manpower for carrying and cable work.
In particular, depending on the purpose of the test, it may be necessary to make the hydrophone
neutral buoyancy and tow it by a cable, or it may be necessary to float it in water for acoustic
measurement, but in the case of the above materials So it is difficult to realize them.
[0015]
Therefore, in order to solve the above-mentioned conventional problems at once, it is an object of
the present invention to provide a compact and lightweight cylindrical cardioid hydrophone
capable of forming cardioid directivity with a single cylinder. is there.
04-05-2019
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[0016]
[Means for Solving the Problems] In order to achieve the above object, the gist of the present
invention is a cylindrical base obtained by compounding light and hard polyvinyl chloride
division cylinders in a hydrophone receiving sensor. Is used as a reinforcing material, and a
lightweight, flexible sheet-like polymer piezoelectric material is mounted as an electroacoustic
transducer on the inner peripheral surface and the outer peripheral surface to solve the abovementioned drawbacks. .
[0017]
This will be described with reference to the embodiment of FIGS. 1 to 5. The cylindrical cardioid
hydrophone of claim 1 of the present invention is a cylindrical sensing part of a hydrophone
formed of a single cylinder, An axially divided cylindrical base with through holes is used as a
reinforcing material, and a polymer piezoelectric material having flexibility is formed on the
inner peripheral surface and the outer peripheral surface of the cylindrical base with the divided
part of the cylindrical base as a boundary. Polymer piezoelectric materials respectively mounted
and mounted on one circumferential surface of the cylindrical substrate in-phase parallel
connection or in-phase series connection to form a nondirectional output, and polymer attached
on the other circumferential surface of the cylindrical substrate It is characterized in that the
piezoelectric materials are connected in reverse phase parallel connection or reverse phase series
connection to make a bi-directional output, and cardioid directivity is obtained by a combined
output of the non-directional output and the bi-directional output.
[0018]
The invention of claim 2 is provided with the two sets of cylindrical sensing parts described
above, and the two sets of cylindrical sensing parts are symmetrically attached to the annular
base at their opposite ends and supported by the shape and mass center, The present invention is
characterized in that the acceleration output voltage generated in each cylindrical sensing part
by the dynamic vibration is offset.
[0019]
Furthermore, according to the invention of claim 3, in the cylindrical cardioid hydrophone
according to claim 1 or 2, a preamplifier for performing impedance conversion on the
nondirectional output and the bidirectional output and outputting the same, and the bidirectional
output. A main amplifier for equalizing the sensitivity of the nondirectional output with the
maximum sensitivity in the direction of 180 degrees with each other, and a phase shifter for
shifting the phase of the nondirectional output or the bidirectional output by π / 2 It is
characterized.
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[0020]
The polymeric piezoelectric material applied to the cylindrical sensing part of the cylindrical
cardioid hydrophone of the present invention has an output voltage depending on the strain due
to the expansion and contraction of the base material as a reinforcing material, like a
conventional PVDF film like a foil film. The PFDF is a PFDF having a thickness of 0.5 mm or
more, which is mainly used to obtain an output voltage by a volume change of the polymeric
piezoelectric material itself.
[0021]
And, when the polymeric piezoelectric material applied to the cylindrical sensing part of the
cylindrical cardioid hydrophone of the present invention is compared with the conventional
piezoelectric ceramic, the main features are as follows.
(1) Being flexible, it is easy to adhere to or adhere to other objects (2) It is resistant to impact and
does not break even if dropped.
(3) Since the g (voltage output) constant is large, the receiving sensitivity is high. (4) The density
is about 1.9 g / cm 2 and relatively light.
[0022]
When making a hydrophone, it is not possible to use a polymeric piezoelectric material as it is, so
some reinforcing material that can withstand water pressure etc. is required, and in the example
of the present invention, for the isolation of vibration, A lightweight and hard polyvinyl chloride
cylinder is divided and used as a cylinder base compounded.
[0023]
That is, the cylindrical sensing portion is mounted along the inner peripheral surface and the
outer peripheral surface of the cylindrical base obtained by compound-joining the through-holed
divided cylinders.
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Here, as an example of mounting, a cylindrical sensing unit in which a polymeric piezoelectric
material is mounted on the inner peripheral surface and the outer peripheral surface of a
cylindrical base obtained by compound-joining a divided cylinder with through holes will be
described.
[0024]
Furthermore, it is composed of a bowl-shaped case that encloses them, and in order to avoid the
influence of the transfer vibration from the body etc., the case is held in the boot by the foam
body so as not to directly touch other solids. The liquid filled in the case and the boot is used as
an acoustic medium to transmit the sound wave from the outside of the boot to the polymeric
piezoelectric material.
[0025]
And in the cylindrical sensing part of the hydrophone, the light and hard polyvinyl chloride
through-hole divided cylindrical substrate is used as a reinforcing material, and the inner and
outer peripheral surfaces of the divided cylindrical substrate are used as electroacoustic
transducers on a lightweight basis. The sheet-shaped polymer piezoelectric material having
flexibility is attached, and the output of the polymer piezoelectric material on the outer
peripheral surface of the sheet is connected in parallel in reverse phase, and the pressure
gradient type bi-directional represented by the equation (1) Get sex.
[0026]
Further, when the amplitude of the output of the polymeric piezoelectric material mounted on
the inner peripheral surface is made equal and the phase is shifted by π / 2 and connected, the
cardioid directivity shown in equation (2) is obtained.
[0027]
In addition, in order to reduce the acceleration sensitivity, two sets of cylindrical sensing parts
are provided, and the cylindrical sensing parts are attached to the annular base at their opposite
ends and supported at the shape and center of mass, each by mechanical vibration. The
acceleration output voltage is suppressed by the electrical circuit connection which is offset by
the output generated in the sensing part, and the decrease in S / N is avoided.
[0028]
Furthermore, in order to further reduce the acceleration transmitted to the cylindrical sensing
portion, both the wedge-shaped case surrounding the cylindrical sensing portion is buried and
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held in the foam which also has an effect of damping the vibration.
[0029]
In addition, the underwater sound sensing unit floats in the foam and oil so that it does not
directly touch other containers, thereby avoiding the influence of vibration from the containers
and the like.
Thereby, good receiving sensitivity frequency characteristics and cardioid directivity
characteristics can be obtained.
[0030]
Therefore, the acceleration output suppression effect is significantly improved over the
conventional wave receiver due to the offsetting effect of the acceleration output voltage of the
cylindrical sensing part and the vibration damping effect by the foam body.
Since no noise output based on the vibration of the body occurs in the sensing part, a broad band
reception sensitivity frequency characteristic having flat characteristics over a wide range is
obtained.
[0031]
Since the hydrophone of the present invention can form cardioid directivity with one cylindrical
shape, acoustic reflection can be achieved as compared to the case where cardioid directivity is
formed by arranging three reception sensors individually. In addition to the great advantage that
the influence of the problem does not occur, the structure becomes simple.
[0032]
The hydrophone of the present invention does not use a member containing air such as a sound
insulating material that changes due to water pressure, and the support member of the sensor
unit is solid, and extends over the entire circumference such as the inner and outer surfaces of
the sensing unit. Since the water pressure is uniformly applied, the change in characteristics due
to the water pressure is extremely small compared to the conventional product.
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[0033]
In order to reduce the weight of the hydrophone of the present invention, each member is made
of synthetic rubber or synthetic resin, and the sensor is a polymeric piezoelectric material having
a specific gravity of about 2.5, and the specific gravity of the conventional piezoelectric ceramic
vibrator is about It is small compared to 7.5 and extremely lightweight because it can be
manufactured using non-metallic materials.
[0034]
For this reason, it is possible to easily realize an underwater floating hydrophone or a neutral
buoyant hydrophone simply by storing the wave receiving sensor in a long hose or the like
together with a commercially available insulating oil or the like.
[0035]
Since the hydrophone's wave receiving sensor is a polymer piezoelectric material that is unlikely
to be cracked or damaged by impact, it is lightweight and preparation of alternative products for
the solution of work complexity and for the prevention of hydrophone breakage and damage, etc.
Is also unnecessary.
[0036]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to FIGS. 1 to 5. FIG.
FIG. 1 is a view showing an embodiment of a cylindrical cardioid hydrophone according to the
present invention, FIG. 2 is a view showing a horizontal directivity pattern by the hydrophone,
and FIG. 3 is a view showing a wiring configuration of a sensor unit in the hydrophone FIG. 4 is a
central longitudinal cross-sectional view of the sensor unit in the same hydrophone, and FIG. 5 is
a cross-sectional view of the sensor unit in the same hydrophone taken along the line I-I.
[0037]
As shown in FIG. 1, the cylindrical cardioid hydrophone is roughly configured to include a sensor
unit 1, a preamplifier 2, and a control unit 3.
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[0038]
As shown in FIGS. 4 and 5, the sensor unit 1 uses, as a reinforcing material, a cylindrical base 4
made of a lightweight and hard material such as polyvinyl chloride, for example.
The cylindrical base 4 is composed of two half-cylinders 4a and 4b which are equally divided in
the axial direction.
The half cylindrical portions 4a and 4b are configured such that both end surfaces in the axial
direction are joined by the compound 5 to form a single cylinder and to vibrate independently.
[0039]
As shown in FIG. 4, the sensor unit 1 is equipped with two sets of cylindrical bases 4 (4A, 4B) of
the above configuration.
The cylindrical bases 4A and 4B are attached to the annular metal base 6 made of a light metal at
opposite ends respectively, and are symmetrically mounted on the upper and lower sides of the
annular base 6.
[0040]
Polymer piezoelectric materials 7 (7a, 7b, 7c, 7d) are respectively mounted on the inner
peripheral surfaces of the cylindrical bases 4A, 4B so as to be opposed to each other with the
compound 5 portion being a bonded portion as a boundary.
As shown in FIG. 3, the polymer piezoelectric materials 7a and 7b mounted on the inner
peripheral surface of the cylindrical base 4A are connected in parallel in phase with the sound
wave, and both ends thereof are one impedance conversion circuit in the preamplifier 2 It is
connected to the input terminal of 2a.
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Further, as shown in FIG. 3, the polymer piezoelectric materials 7c and 7d mounted on the inner
peripheral surface of the cylindrical base 4B are connected in parallel in phase with the sound
wave, and both ends thereof are on the inner peripheral surface of the cylindrical base 4A. It is
connected in parallel to the attached polymeric piezoelectric materials 7a and 7b.
[0041]
As a result, from the impedance conversion circuit 2a, a non-directional output is obtained in
which a signal input from the polymer piezoelectric materials 7a, 7b, 7c, 7d with high impedance
is converted to low impedance and amplified (FIG. 2) Output b).
[0042]
Similarly, on the outer peripheral surface of each of the cylindrical bases 4A and 4B, the
polymeric piezoelectric materials 7 (7e and 7f) are respectively attached so as to be opposed to
each other with the compound 5 portion which is a bonded portion as a boundary.
The polymeric piezoelectric materials 7e and 7f mounted on the outer peripheral surface of the
cylindrical base 4A are connected in parallel in reverse phase to the sound wave as shown in FIG.
3, and both ends thereof are the other impedance conversion circuit in the preamplifier 2 It is
connected to the 2b input terminal.
Further, as shown in FIG. 3, the polymeric piezoelectric materials 7g and 7h mounted on the
outer peripheral surface of the cylindrical base 4B are connected in parallel in opposite phase to
the sound wave, and both ends thereof are mounted on the outer peripheral surface of the
cylindrical base 4A. It is connected in parallel to the polymer piezoelectric materials 7e and 7f.
[0043]
As a result, from the impedance conversion circuit 2a, a bi-directional output is obtained in which
signals input from the high-polymer piezoelectric materials 7e, 7f, 7g, 7h with high impedance
are converted to low impedance and amplified (FIG. 2) Output of A).
[0044]
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Thus, in the embodiment shown in FIG. 4 and FIG. 5, one wave receiving sensor 8a for obtaining
a non-directional output formed on the inner peripheral surface side of the cylindrical bases 4A,
4B, and the cylindrical base 4A. A pair of cylindrical sensing units 8 are formed by two wave
receiving sensors 8b and 8c for obtaining a bi-directional output formed on the outer peripheral
surface side of and 4B.
The sensor unit 1 is provided with two sets of cylindrical sensing units 8 with an annular base 6
as a boundary.
[0045]
The sensor unit 1 configured as described above is inserted in a bowl-shaped case 9 so as to
surround the whole, and is supported at the shape and center of mass including the case 9, the
annular base 6 and the cylindrical sensing unit 8. It is done.
Specifically, as shown in FIG. 4, the side end face of the annular base 6 is fastened with a screw
10.
Thereby, the acceleration output voltage generated in each cylindrical sensing portion 8 by the
mechanical vibration is offset.
[0046]
As shown in FIG. 4, the case 9 to which the sensor unit 1 is fixed is held in a boot 12 made of
synthetic rubber, synthetic resin, or the like by a foam 11 that has good sound transmission.
In addition, the case 9 and the boot 12 are filled with a filling liquid 13 as an acoustic medium.
[0047]
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11
As shown in FIG. 4, a light metal case 14 made of, for example, aluminum or resin is inserted into
the upper portion of the sensor unit 1 in the boot 12.
At the bottom of the case 14, through terminals 16 are provided for electrically connecting the
polymer piezoelectric materials 7a, 7b, 7e, 7f of the cylindrical base 4A and the preamplifier 2
with lead wires 15. There is.
[0048]
As shown in FIG. 4, a waterproof cap 17 is inserted in the case 14 so as to cover the opening of
the case 14 from the top.
The boot 12 and the cap 17 are respectively fixed to the case 14 by a fastening band 18 such as
a metal band.
The space formed by the case 14 and the cap 17 is filled with a filling material 19 for filling the
space and eliminating the air layer.
[0049]
The preamplifier 2 is electrically connected to the control unit 3 via a cable 20 which is led out
from an opening at the top of the cap 17.
The control unit 3 is a phase shifter connected to the main amplifiers 3a and 3b connected to the
impedance conversion circuits 2a and 2b and to one main amplifier (in the example of FIG. 1, the
main amplifier 3b on the bidirectional output side). It comprises 3c.
[0050]
In the main amplifiers 3a and 3b, the relative voltages are set so that the maximum sensitivity of
the bi-directional outputs from the impedance conversion circuit 2b in the direction of 180
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degrees with each other and the sensitivity of the nondirectional output from the impedance
conversion circuit 2a are equal. The amplification degree is adjusted to amplify the signal.
Furthermore, in the main amplifiers 3a and 3b, when used as an active hydrophone such as a
towing sonar, since the frequency to be received is known, the amplitude is set in accordance
with the frequency.
On the other hand, when it is used as a passive hydrophone such as Sonobuoy, since the
frequency to be received is unknown, the amplitude is adjusted each time.
Further, the transfer device 3c shifts the phase of the signal from one of the main amplifiers (in
the example of FIG. 1, the main amplifier 3b on the bidirectional output side) by π / 2 and
outputs it.
[0051]
A through hole 21 is formed in a portion of the cylindrical base 4 where the polymeric
piezoelectric material 7 is not mounted.
As a result, the weight of the cylindrical base 4 itself can be reduced, pressure distortion can be
avoided, and sound waves from the outside of the boot 12 can pass through the inside of the
cylindrical base 4.
Further, each impedance conversion circuit 2 a, 2 b of the preamplifier 2 is operated by a DC
power supply supplied via the cable 20.
[0052]
According to the cylindrical cardioid hydrophone configured as described above, the sound wave
from the outside of the boot 7 uses the filling liquid 11 filled in the case 4 and the boot 7 as an
acoustic medium, and the polymeric piezoelectric materials 2a, 2b, 2c. , 2d and 2e, 2f, 2g, 2h.
04-05-2019
13
The mechanical distortion caused by this sound wave is converted into an electrical output (a
non-directional output and a bi-directional output) via the impedance conversion circuits 2a and
2b of the preamplifier 2, and this electrical output It is input to the control unit 3 via
Thereafter, in the main amplifiers 3a and 3b of the control unit 3, the relative voltage
amplification is adjusted such that the maximum sensitivity in the direction of 180 degrees of the
bidirectional output and the sensitivity of the nondirectional output become equal. .
Then, cardioid directivity is obtained by combining the bi-directional output whose phase is
shifted by π / 2 and the non-directional output by the phase shifter 3c (output C in FIG. 2).
[0053]
By the way, in the embodiment described above, the polymer piezoelectric materials (7a, 7b and
7c, 7d) mounted on the inner peripheral surface of each cylindrical base 4A, 4B are connected in
parallel in phase with the sound wave, Although the polymer piezoelectric materials (7e, 7f and
7g, 7h) attached to the outer peripheral surface of 4A, 4B are connected in parallel in reverse
phase to the sound wave, they are illustrated and described, but the cylindrical substrates 4A, 4B
Polymer piezoelectric materials (7a, 7b and 7c, 7d) mounted on the inner peripheral surface are
connected in series in phase with sound waves, and polymer piezoelectric materials (7e) mounted
on the outer peripheral surface of each cylindrical base 4A, 4B , 7f and 7g, 7h) can be connected
in series in reverse phase to the sound wave to obtain the same effect. Further, a polymeric
piezoelectric material (7a, 7b and 7c, 7d) mounted on the inner peripheral surface of the
cylindrical base 4A, 4B and a polymeric piezoelectric material (7e, 7f) mounted on the outer
peripheral surface of the cylindrical base 4A, 4B. And 7g, 7h) may be reversed.
[0054]
As described above, according to the present invention, as a wave receiving sensor of a
hydrophone formed by a single cylinder, an axially divided cylindrical base with through holes is
used as a reinforcing material, and the inner peripheral surface of the cylindrical base is used. A
polymer piezoelectric material having flexibility is mounted on the upper and outer peripheral
surfaces of the cylindrical base with the divided portion of the cylindrical base as a boundary,
and the polymer piezoelectric materials mounted on one peripheral surface of the cylindrical
base are connected in phase parallel connection or In-phase series connection to make a nondirectional output, and polymer piezoelectric materials mounted on the other circumferential
04-05-2019
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surface of the cylindrical base are connected in anti-phase parallel connection or anti-phase
series to make a bi-directional output. The cardioid directivity can be obtained by equally
adjusting the amplitude of the bi-directional output, and shifting the phase by π / 2 and
combining the two outputs.
[0055]
Since the hydrophone of the present invention can form cardioid directivity with one cylindrical
shape, acoustic reflection can be achieved as compared to the case where cardioid directivity is
formed by arranging three reception sensors individually. There is a great advantage that there is
no influence of the above, and there is also an advantage that the structure is simple and
lightweight.
[0056]
Further, the acceleration output suppression effect is significantly improved over the
conventional wave receiver due to the offsetting effect of the acceleration output voltage of the
sensing part and the vibration damping effect by the foam body.
Since no noise output based on the vibration of the body occurs in the sensing part, a broad band
reception sensitivity frequency characteristic having flat characteristics over a wide range is
obtained.
[0057]
The hydrophone of the present invention does not use a member containing air such as a sound
insulating material that changes due to water pressure, and the support member is solid, and the
water pressure is uniform over the entire inner and outer surfaces such as the inner and outer
surfaces of the sensing part. The change in characteristics due to water pressure is extremely
small compared to conventional products.
[0058]
Since the hydrophone's wave receiving sensor is a polymer piezoelectric material that is unlikely
to be cracked or damaged by impact, it is lightweight and preparation of alternative products for
the solution of work complexity and for the prevention of hydrophone breakage and damage, etc.
Is also unnecessary.
04-05-2019
15
[0059]
The effects of the embodiment of the present invention are as follows.
In order to reduce the weight of the hydrophone of the present invention, each member is made
of synthetic rubber or synthetic resin, and the sensor is a polymeric piezoelectric material having
a specific gravity of about 2.5, and the specific gravity of the conventional piezoelectric ceramic
vibrator is about It is small compared to 7.5 and extremely lightweight because it can be
manufactured using non-metallic materials.
[0060]
For this reason, it is possible to easily realize an underwater floating hydrophone or a
hydrophobe having a neutral buoyancy simply by storing the wave receiving sensor in a long
hose or the like together with a commercially available insulating oil or the like.
In addition, it is possible to easily realize an underwater floating hydrophone or a neutral
buoyant hydrophone simply by storing the wave receiving sensor in a long hose or the like
together with a commercially available insulating oil or the like.
[0061]
Brief description of the drawings
[0062]
1 is a diagram showing an embodiment of a cylindrical cardioid hydrophone according to the
present invention.
[0063]
2 is a diagram showing a horizontal directivity pattern by the same hydrophone.
[0064]
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3 is a diagram showing the wiring configuration of the sensor unit in the same hydrophone.
[0065]
4 is a central longitudinal cross-sectional view of the sensor portion in the same hydrophone.
[0066]
5 is a cross-sectional view of the sensor portion of the same hydrophone I-I line.
[0067]
Explanation of sign
[0068]
DESCRIPTION OF SYMBOLS 1 ... Sensor part, 2 ... Preamplifier, 2a, 2b ... Impedance conversion
circuit, 3 ... Control part, 4 (4A, 4B) ... Cylindrical base, 5 ... Compound, 6 ... Annular base, 7 (7a7h) ... Polymer piezoelectric material, 8: cylindrical sensing part, 8a-8c: received wave sensor, 9:
case, 10: screw, 11: foam, 12: boot, 13: filling liquid, 14: case, 15: lead wire , 16: through
terminal, 17: cap, 18: tightening band, 19: filler, 20: cable, 21: through hole.
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