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JP2012251826

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DESCRIPTION JP2012251826
PROBLEM TO BE SOLVED: To make it possible to measure the performance of an underwater
wave transmitter simply and with high accuracy. SOLUTION: An oscillator 11 for generating a
predetermined inspection signal, a power amplifier 12 for amplifying the inspection signal to
drive the underwater wave transmitter 5, and the atmosphere installed at a predetermined height
from the water surface, And a vibration measurement device 13 for measuring the vibration
amplitude of the acoustic emission surface when the underwater wave transmitter 5 is driven to
emit a sound wave emitted from the underwater wave transmitter 5 into water. [Selected figure]
Figure 1
Inspection apparatus and inspection method for underwater wave transmitter
[0001]
The present invention relates to an inspection apparatus and an inspection method for an
underwater transmitter that transmits sound waves in water.
[0002]
Generally, in order to measure the acoustic performance of an underwater wave transmitter that
transmits sound waves such as ultrasonic waves into water, a test aquarium facility dedicated to
a large sound field in the sea or for acoustic tests is used, and the wave receiving sensitivity
performance is An obvious standard receiver is used.
[0003]
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The underwater wave transmitter and the standard wave receiver are disposed facing each other
at a predetermined distance in water, and the sound wave radiated from the water wave
transmitter is received by the standard wave receiver.
And the acoustic performance of the underwater transmitter is obtained by analyzing the
received wave signal.
In addition, it is general to measure using a test water tank installation with a deep water depth
and little fluctuation of water flow and water temperature so that the hydraulic characteristic of
impedance may be stabilized.
[0004]
FIG. 10 is a block diagram of a measuring device 100 used when measuring the acoustic
performance of the underwater wave transmitter. The measuring apparatus 100 includes an
oscillator 101, a power amplifier 102, a standard receiver 111, a preamplifier 112, a band pass
filter 113, and an oscilloscope 114. The underwater wave transmitter 103 and the standard wave
receiver 111 are suspended in a large test water tank and installed, and the sound wave from the
water wave transmitter 103 is received by the standard wave receiver 111.
[0005]
In such a configuration, a test signal of a sine wave having a predetermined frequency is output
from the oscillator 101, and the test signal is power-amplified by the power amplifier 102 and
output to the underwater transmitter 103. The underwater wave transmitter 103 emits an
acoustic wave at a frequency corresponding to the power-amplified inspection signal into the
water.
[0006]
The sound waves radiated into the water are received by the standard receiver 111 at a distance
W. Since the sound wave has a predetermined sound velocity, it is received with a delay
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corresponding to the distance W.
[0007]
The signal received by the standard receiver 111 is amplified by the preamplifier 112 and input
to the oscilloscope 114, and waveform observation and the like are performed by the
oscilloscope 114.
[0008]
The measurement results by these measuring devices 100 are calculated as the transmission
sensitivity of the underwater transmitter 103 based on the following equation 1.
[0009]
Sv = Vout-Vin-Mv-PG + 20 log (W) (1) where: Sv: transmission sensitivity [dB re 1 μPa / V; W = 1
m] Vout: output voltage of standard receiver [dB] Vin: underwater Transmitter input voltage [dB]
Mv: Reception voltage sensitivity of standard receiver [dB] PG: Preamplifier gain [dB] W: Distance
between transmitter and receiver [m].
[0010]
The transmission sensitivity inspection method of such an underwater wave transmission device
is disclosed, for example, in JP-A-8-79898.
In this JP-A-8-79898, a transducer of unknown sensitivity and a reference underwater wave
transceiver of known sensitivity are combined, suspended in water at a predetermined distance,
and a transducer of unknown sensitivity is tested. It is a method.
[0011]
Japanese Patent Application Laid-Open No. 8-79898
[0012]
However, in the inspection method as described above, not only the underwater wave transmitter
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but also the standard wave receiver need to be installed in water, so there is a problem that the
measurement operation requires man-hours.
In particular, a lot of working time is required because the underwater wave transmitter and the
standard wave receiver have to be installed to maintain a predetermined distance in water.
In addition, the reason for installing these so as to keep a predetermined distance in water is that
the sound wave emitted from the underwater wave transmitter is input to the standard wave
receiver via (other than, reflection, etc.) a member other than water. To prevent
[0013]
Then, the main object of this invention is to provide the inspection apparatus and water
inspection method of the underwater wave transmitter which can perform performance
measurement of a water wave transmitter simply and with high precision.
[0014]
In order to solve the above problems, the invention according to the inspection apparatus for an
underwater transmitter comprises an oscillator for generating a predetermined inspection signal,
a power amplifier for amplifying the inspection signal and driving the underwater transmitter,
and And a vibration measurement device installed in the atmosphere at a height position of and
measuring the vibration amplitude of the acoustic emission surface of the driven underwater
wave transmitter.
[0015]
The invention also relates to a driving procedure for driving the underwater wave transmitter
installed in the water, and irradiating the detection light into the water from the atmosphere to
emit acoustic radiation in the underwater wave transmitter. Measuring the vibration amplitude of
the surface.
[0016]
Since the vibration measuring device is installed in the atmosphere, performance measurement
of the underwater wave transmitter can be performed easily and with high accuracy.
[0017]
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It is a block diagram of an inspection device concerning a 1st embodiment of the present
invention.
It is a flowchart which shows the inspection procedure using the inspection apparatus
concerning 1st Embodiment.
It is a figure which shows the vibration state in the piezoelectric submersible wave transmitter
driven by the test | inspection apparatus concerning 1st Embodiment, (a) is a state which
expanded and (b) is a figure which showed the contracted state.
It is a figure which shows a mode that several points are measured by the inspection apparatus
concerning 1st Embodiment.
The transmission sensitivity (the curve of the solid line) to the frequency of the inspection signal
measured using the inspection apparatus according to the first embodiment and the transmission
sensitivity (the curve of the dotted line) to the frequency of the inspection signal measured by the
known inspection method It is the figure which compared.
It is a figure which shows a mode that a point with the largest amplitude is measured by the
inspection apparatus concerning the 2nd Embodiment of this invention. It is the figure which
compared the wave transmission sensitivity (curve of a continuous line) obtained by the
inspection method concerning 2nd Embodiment with the wave transmission sensitivity (curve of
a dotted line) obtained by measuring by a well-known method. It is a graph which shows the
example of the measured value with respect to the measurement depth concerning the 3rd
Embodiment of this invention, (a) is a case where measured value is a vibration velocity, (b) is a
case where measured value is a resonant frequency. It is a block diagram of an inspection device
concerning a 3rd embodiment of the present invention. It is a block diagram of a measuring
device concerning related art.
[0018]
First Embodiment A first embodiment of the present invention will be described. FIG. 1 is a block
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diagram of an inspection apparatus 2A for an underwater transmitter according to a first
embodiment of the present invention.
[0019]
The inspection apparatus 2A includes an oscillator 11 that generates an inspection signal of a
predetermined frequency, a power amplifier 12 that amplifies the inspection signal, and a
vibration measurement device 13 that measures the vibration amplitude of the acoustic radiation
surface of the underwater transmitter 5 by infrared rays or the like. Have. The underwater
transmitter 5 is installed in a water tank 21 filled with water 22, and a test signal is input from
the power amplifier 12 to the underwater transmitter 5. The water depth of the underwater wave
transmitter 5 is a water depth D1 set in advance, and the height from the water surface of the
vibration measurement device 13 is a height D2 set in advance.
[0020]
In the following, the case where a test signal such as a sine wave is generated from the oscillator
11 will be described, but the present invention is not limited to the sine wave as the test signal.
[0021]
Further, in the present embodiment, a bent disk type nondirectional underwater wave transmitter
using a piezoelectric vibrator as the underwater wave transmitter 5 will be described as an
example, but the present invention is not limited to such a wave transmitter. .
[0022]
The operation of the underwater transmitter inspection system 2A having such a configuration
will be described with reference to the flowchart of FIG.
First, a test signal of a continuous sine wave is output from the oscillator 11 (step S1), and power
is amplified by the power amplifier 12 (step S2).
The amplified test signal is input to the underwater wave transmitter 5 (step S3), whereby the
underwater wave transmitter 5 causes continuous vibration to emit a sound wave into the water
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(step S4).
[0023]
FIG. 3 is a view showing a vibration state of the underwater transmitter 5. As shown in FIG. FIG. 3
(a) shows a state in which the underwater wave transmitter 5 is inflated by an inspection signal,
and FIG. 3 (b) shows a state in which it has contracted. Such vibrations become sound waves and
are emitted into the water. In addition, the piezoelectric vibrator is used for the underwater wave
transmitter 5, and the sound wave radiated | emitted turns into an ultrasonic wave.
[0024]
The sound pressure P of the sound wave radiated into the water is given by the following
equation 2.
[0025]
P = ρf U / 2 d (2) where: 密度: density of sound medium f: frequency U: volume velocity d:
distance from sound source to receiving point
[0026]
Sound waves of this sound pressure are emitted into the water.
That is, when a sound wave is radiated into water, the vibrating acoustic emission surface
vibrates water as an acoustic medium, and the larger the amplitude, the larger the sound
pressure.
Since the volume velocity U can be calculated from the acoustic radiation area and its vibration
velocity, the sound pressure can be obtained by measuring the amplitude over the entire acoustic
radiation surface with the vibration measurement device 13. And transmission sensitivity can be
converted by measuring this vibration amplitude (Steps S5 and S6).
[0027]
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Note that, in order to obtain more accurate transmission sensitivity, it is desirable to measure the
amplitude distribution of the entire acoustic radiation surface (step S7). FIG. 4 shows how to
measure at a large number of measurement points in order to measure the vibration distribution.
In FIG. 4, a symbol P indicates a measurement point. Moreover, the code | symbol 5a has shown
the sound radiation surface.
[0028]
The vibration amplitude at this time has a frequency characteristic according to the underwater
impedance characteristic of the underwater transmitter 5, so that the frequency characteristic of
the transmission sensitivity can be determined by measuring the amplitude for each frequency.
[0029]
Based on these conditions, in the present embodiment, an optical non-contact vibrometer having
high measurement accuracy among displacement sensors is used as the vibration measuring
device 13.
This optical noncontact vibrometer irradiates a laser (detected light) to the acoustic emission
surface of the underwater wave transmitter 5, and the physical information (for example, the
light contained in the reflected light reflected by the acoustic emission surface 5a) Amplitude etc.
are measured using the Doppler effect, delay time).
[0030]
FIG. 5 compares the transmission sensitivity obtained by measurement by a known inspection
method (dotted curve) and the transmission sensitivity obtained using the inspection apparatus
2A according to the present embodiment (solid curve). The result is As the inspection conditions,
the same underwater wave transmitter is installed at the same water depth, and the frequency
range of ± 0.1 [kHz] and ± 0.2 [kHz] for the frequency f [kHz] is set. Sound waves are generated
by the inspection signal of frequency).
[0031]
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Thereby, it turns out that the difference of the test result obtained by both test methods is very
small. Therefore, the inspection method according to the present invention can obtain
measurement results equivalent to those of known inspection methods.
[0032]
On the other hand, regarding the measurement time, the inspection method according to the
present invention could be performed in about one-fifth of that in the case of the known
inspection method.
[0033]
As described above, it has been proved that the inspection method according to the present
invention can perform inspection with a small number of inspection steps without causing a
decrease in measurement accuracy.
Second Embodiment Next, a second embodiment of the present invention will be described. In
addition, regarding the same configuration as the first embodiment, the description will be
appropriately omitted using the same reference numerals.
[0034]
In the first embodiment, the measurement accuracy is improved by measuring the amplitude of
the entire acoustic radiation surface of the underwater wave transmitter. However, increasing the
measurement points will increase the measurement time and analysis time. Also, the number of
measurement points and the measurement accuracy do not show a linear proportional
relationship, and the measurement accuracy approximates to a certain value (true value) with
respect to the number of measurement points. Here, the true value is a true value that does not
include a measurement error.
[0035]
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And the required range (required accuracy) exists in the measurement accuracy. Therefore, it is
not necessary to measure meaninglessly with high accuracy. Assuming that the required
accuracy is an accuracy according to a conventionally used inspection method, it can be said that
the result shown in FIG. 5 of the first embodiment is an inspection method that satisfies the
required accuracy. And limiting to the number of measurements satisfying the required accuracy
leads to a reduction of unnecessary measurement man-hours.
[0036]
From this point of view, in the present embodiment, as shown in FIG. 6, only one point in the
center of the acoustic radiation surface 5a where the amplitude is maximum is measured. FIG. 6
shows the measurement point P, and the alternate long and short dash line shows the vibration
of the acoustic radiation surface 5a approximated to a triangle (vibration amplitude approximate
distribution) with the position of the maximum amplitude (the position of the measurement point
P) as a vertex.
[0037]
And FIG. 7 compares the transmission sensitivity (curve of a solid line) obtained by such one
point measurement with the transmission sensitivity (curve of a dotted line) obtained by
measurement by a well-known method. FIG.
[0038]
As understood from FIG. 7, the transmission sensitivity obtained by measuring one point shows
very good agreement with the transmission sensitivity obtained using a known method.
The time required to obtain the transmission sensitivity by the method according to the present
embodiment was about 1/20 of that in the known method.
[0039]
This means that if the measurement method according to the present embodiment is applied to
one point with the maximum amplitude, it is possible to significantly reduce the number of
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measurement steps while preventing a decrease in measurement accuracy. Therefore, the
measurement work efficiency is improved. Third Embodiment Next, a third embodiment of the
present invention will be described. In addition, regarding the same configuration as the first
embodiment, the description will be appropriately omitted using the same reference numerals.
[0040]
Since the impedance characteristic of the underwater wave transmitter changes due to the
acoustic load, the vibration velocity and the resonance frequency of the acoustic radiation
surface change according to the water depth at which the water wave transmitter is installed. For
this reason, in the past, measurement was carried out by installing the underwater wave
transmitter at a water depth of several meters or more at which the impedance characteristic is
stabilized.
[0041]
FIG. 8 is a graph showing changes in vibration velocity (FIG. 8 (a)) and resonance frequency (FIG.
8 (b)) with respect to the measurement depth. Both the vibration velocity and the resonance
frequency show large values as the measurement depth becomes shallow, and it is understood
that it becomes difficult to obtain accurate transmission sensitivity.
[0042]
However, in the case of setting the underwater wave transmitter in a deep place of water depth,
naturally, a large ultrasonic test tank facility is required. Therefore, in the present embodiment,
characteristics such as wave transmission sensitivity can be obtained by a simpler inspection
method than the conventional inspection method without requiring a large ultrasonic test water
tank facility and without reducing the measurement accuracy. To be able to As a specific method
for this, in the present embodiment, correction data is obtained in advance, and measurement
data is corrected based on the correction data.
[0043]
As shown in FIG. 8, since the vibration velocity and the resonance frequency change according to
the water depth, these characteristics are measured in advance with respect to the water depth,
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and the vibration measuring device 13 is Remember.
[0044]
An example of correction will be described with reference to FIG. 8 (a).
In FIG. 8A, it is assumed that the underwater transmitter is set to the depth D3, the measurement
value is m1, and the true value to be obtained is m2. The true value referred to here is a value
having a deep depth and having no change in impedance characteristics or a value that can
substantially ignore a change in impedance characteristics or the like, and is a value of dotted
line A. On the other hand, it is known from the correction data that when the underwater
transmitter is set to the depth D3, the measured value of M1 is measured even if the true value is
M2, due to the change of the impedance characteristic or the like. Therefore, using the
proportional distribution method, the true value m2 is calculated as m2 = m1 * (M2 / M1). M2 /
M1 is a correction coefficient corresponding to the depth.
[0045]
By performing such correction, it is possible to obtain transmission sensitivity and the like while
suppressing a decrease in measurement accuracy even in a small water tank 21 which can be
installed indoors.
[0046]
In addition, if the correction data is applied to a water depth of, for example, several hundred
meters, the underwater transmitter is located at a deep depth by using the measured value of the
underwater transmitter obtained by installing in a shallow water depth The transmission
sensitivity of can be calculated.
Therefore, simple and wide measurement range is possible. Fourth Embodiment Next, a fourth
embodiment of the present invention will be described. In addition, regarding the same
configuration as the first embodiment, the description will be appropriately omitted using the
same reference numerals.
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[0047]
In each of the previous embodiments, the number of underwater transmitters to be measured
was one. However, in some cases it may be desirable to evaluate multiple underwater
transmitters. In such a case, if installation and replacement work is performed for each
underwater wave transmitter, the measurement efficiency is degraded.
[0048]
Therefore, in the present embodiment, a plurality of underwater wave transmitters are installed
at the same time, and it is possible to measure individually while scanning the vibration
measurement device.
[0049]
FIG. 9 is a block diagram of such an underwater transmitter inspection system 2B.
The inspection signal generated by the oscillator 11 is amplified by the power amplifier, and is
input to the plurality of underwater transmitters 5a to 5n installed at the depth D1. Thereby,
each underwater wave transmitter 5a-5n emits a sound wave.
[0050]
Therefore, the vibration measuring device 13 is scanned by the scanning device 16. Then, when
the vibration measuring device 13 is positioned directly above one underwater wave transmitter
5, the vibration measuring device 13 irradiates laser light toward the acoustic emission surface
of the water wave transmitter 5 to perform measurement. . Thereafter, the scanning device 16
moves the vibration measuring device 13 to a position immediately above the next underwater
wave transmitter to perform measurement. Such movement of the vibration measurement device
13 and measurement are repeated by the number corresponding to each of the underwater wave
transmitters 5a to 5n.
[0051]
As a result, it becomes possible to continuously acquire the transmission sensitivity of a plurality
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of underwater wave transmitters, and it is possible to significantly reduce the number of
measurement steps.
[0052]
The present invention is not limited to the embodiments described above, and can be
appropriately changed according to the type and shape of the underwater wave transmitter and
the purpose of use.
[0053]
2A, 2B inspection apparatus 5, 5a to 5n underwater wave transmitter 11 oscillator 12 power
amplifier 13 vibration measuring device 16 scanning device 21 water tank
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