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JPH07218477

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Notice
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
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH07218477
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
exploration apparatus, and more particularly, porous materials such as earth and sand, concrete,
refractory material and soft ceramics, viscoelastic materials such as heterogeneous non-metallic
materials, rubber and soft plastic, The present invention also relates to a search apparatus for
searching for thickness of fats and oils, fresh concrete, high-viscosity materials such as asphalt,
and foreign substances to be buried inside these.
[0002]
2. Description of the Related Art The thickness of a metal material or hard ceramic, presence or
absence of internal defects, or the depth or depth of a liquid such as water or oil, and foreign
substances floating or buried therein (for example, fish schools in the sea) are searched A search
device is described, for example, in "Ultrasonic measurement", Noboru Niwa, March, 1982,
published by Shoindo, pages 65-93.
[0003]
In this type of search device, the velocity of the acoustic vibration wave propagating in the object
is uniquely determined by the density and the elastic modulus of the object, and the acoustic
vibration wave is different in at least one of the density and the elastic modulus 2 It uses the
principle that part of it is reflected at the interface of two objects.
[0004]
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More specifically, in this type of search device, a pulsed acoustic vibration wave with a very short
width is transmitted from the transmitter in contact with the surface of the object (liquid level)
toward the inside of the object.
Start timing at the same time.
The transmitted acoustic vibration wave propagates inside the object at an inherent propagation
velocity which is uniquely determined by the density and elastic modulus of the object, and is
eventually reflected at the end surface (bottom surface) of the object. If a defect or foreign matter
is present inside the object, the defect or foreign matter is also reflected. When the acoustic
vibration wave reflected by the end face etc. is received by the receiver, the search device stops
measuring time, and the elapsed time from transmitting the acoustic vibration wave to receiving
the reflected acoustic vibration wave Get Then, the search device obtains the thickness (depth) of
the object or the distance to the defect and the foreign matter based on the progress result and
the propagation velocity of the acoustic vibration wave.
[0005]
Usually, as an acoustic vibration wave used by this kind of search device, an ultrasonic wave
(usually 100 kHz or more and several MHz) or more in the audible range (20 kHz) or more is
used. This is because the directivity of the acoustic vibration wave becomes stronger as the
frequency becomes higher, and the oscillation of the pulse vibration wave with a narrow time
width becomes easy. That is, by using an acoustic vibration wave of high frequency, a search in a
specific direction can be accurately performed, and a minute defect or foreign substance can be
detected (resolution is improved).
[0006]
In addition, as a conventional exploration device, there is a so-called underground exploration
radar that explores underground structures or deposits in the ground. This kind of probe utilizes,
for example, that electromagnetic wave pulses in the VHF band are reflected at interfaces of
different electrical properties (dielectric constants).
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2
[0007]
[Problems to be solved by the invention] On the other hand, in the case of rebuilding a building,
subway work, road work, etc., it is necessary to accurately grasp the position of a pipe etc. buried
in soil, concrete, etc. It is considered to be extremely important.
[0008]
However, ultrasound is greatly attenuated by porous objects, inhomogeneous substances, and
highly viscous substances.
Specifically, the propagation distance of the ultrasonic waves to these substances is extremely
short, and the ultrasonic waves of 100 kHz or more can hardly propagate. That is, in the
conventional exploration equipment using ultrasonic waves, porous materials or heterogeneous
materials such as earth and sand, concrete, refractory material, and soft ceramics, visco-elastic
materials such as rubbers, soft plastics, fats and oils, fresh concrete, etc. For non-metallic
materials such as high viscosity and slurry-like fluid, there is a problem that exploration can not
be performed.
[0009]
Further, in the conventional underground exploration radar, since boundary surface reflection
due to a difference in dielectric constant is detected, there is a problem that it can not be applied
to a conductive material such as carbon-containing brick. Furthermore, this type of underground
exploration radar has the problem of being very expensive. Therefore, it is a fact that a search
device that can be used for building construction, subway construction, road construction, etc.
has not been obtained yet.
[0010]
The present invention provides a relatively simple and inexpensive search device capable of
searching for thickness, internal defects, and embedded foreign matter for an object having a
large attenuation effect to ultrasonic waves. With the goal.
[0011]
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Another object of the present invention is to provide a relatively simple and inexpensive search
device capable of searching for conductive objects with thickness, internal defects, and
embedded foreign matter.
[0012]
SUMMARY OF THE INVENTION According to the present invention, a vibrating reed driven by a
super magnetostrictive vibrating device having high response to the rising and falling
characteristics of the exciting coil, and the vibration direction and / or the direction
perpendicular to the vibration direction. Passive damper or active damper, excitation coil
accessory circuit or transmission sensor for detecting the transmission signal of the vibrating
reed, the bottom surface of the non-metallic material and / or its internal defect, the reception
signal reflected from the embedded foreign object Excitation coil accessory circuit or wave
receiving sensor to be detected, time difference detection circuit comparing the waveforms of the
transmission signal and the reception signal and detecting the time difference, and vibration
wave propagation of the nonmetallic material previously set or measured with the time
difference The thickness of the nonmetallic material, the internal defect, and the distance
calculating circuit for calculating the distance from the speed to the thickness of the nonmetallic
material, the internal defect and the embedded foreign matter from the velocity Locator fine
buried foreign matter can be obtained.
[0013]
Further, according to the present invention, in the method of searching for the thickness of a
medium that can not substantially propagate ultrasonic waves and the thickness of a medium
containing a conductive substance, the embedded foreign matter in the medium, and the internal
defect of the medium, The vibration of the magnetostrictive element is used to generate a
vibration wave, the vibration wave is transmitted toward the inside of the medium, the reflected
wave is received, the thickness of the medium, the foreign object embedded in the medium, And
searching for an internal defect of the medium.
[0014]
Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 shows a first embodiment of the present invention.
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The search apparatus of this embodiment generates a super magnetostrictive vibration device 11
which generates a vibration wave and receives the reflected vibration wave, a power supply 12
which drives the super magnetostrictive vibration device, and the super magnetostrictive
vibration device 11 as a search target. It has a heavy cone 13 for bringing into close contact and
an operation processing unit 14 which performs a predetermined operation based on the output
of the giant magnetostrictive vibration device 11.
[0015]
The giant magnetostrictive vibration device 11 has a round bar-shaped giant magnetostrictive
material 15 made of an intermetallic compound such as Te-Fe-Dy (terbium-iron-disprhodium),
and an excitation coil connected to the power source 12 around it. It has a configuration in which
16 is wound.
[0016]
The giant magnetostrictive material 15 has a magnetostrictive property of 1,500 to 2,000 ppm, a
compressive strength of 700 MPs, an energy density of 1,400 to 25,000 J / m @ 3, and an
electro-mechanical coupling coefficient of 75%.
In addition, the giant magnetostrictive material 15 has a preload effect that the magnetostriction
rate increases when a magnetic field is applied in a state where preload is applied in advance.
The giant magnetostrictive material 15 also exhibits an inverse magnetostrictive effect (a billy
effect) in which the magnetic characteristics change as a result of the application of mechanical
strain, as with a general ferromagnetic material.
Further, from the eddy current characteristics, the upper limit frequency fc during continuous
driving is represented by fc = 2ρe / μs D2, (ρe: electrical resistivity, μs: permeability, D:
diameter), for example, D = 6 mm The giant magnetostrictive material is about 1.7 kHz (1 kHz
practically). In the case of pulse driving, up to several kHz is possible.
[0017]
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The exciting coil 16 is accommodated in a thin-walled cylindrical ferromagnetic yoke 17. A screw
is cut at the upper end and the lower end of the outer periphery of the yoke 17, and a base 18
made of a ferromagnetic material and a front lid 19 are respectively screwed together. Here, the
yoke 17, the base 18, and the front lid 19 constitute a magnetically closed circuit with respect to
the magnetomotive force of the exciting coil 16.
[0018]
Inside the front lid 19, a part of the connecting rod 21 connecting the giant magnetostrictive
material 15 and the vibrating reed 20, and a compression spring 23 disposed between the ridge
22 of the connecting rod 21 and the front lid 19 are provided. It is housed. The compression
spring 23 applies a preload to the giant magnetostrictive material 15 through the coupling rod
21 to improve the magnetostriction rate of the giant magnetostrictive material 15. The
compression force is determined by the screw between the yoke 17 and the front lid 19. The
total amount can be adjusted. Further, between the front lid 19 and the vibrating reed 20, a
damper 24 made of rubber or synthetic resin having an appropriate vibration damping
characteristic is disposed.
[0019]
The base 18 is fixed to the upper end of the sound absorbing sound insulation cylinder 25, and
the vibrating reed 20 is supported by the cylindrical surface friction damper 26 near the lower
end of the sound absorbing sound insulation cylinder 25. The illustrated sound absorbing sound
insulation cylinder 25 has a three-layer structure in which a sound absorbing material 27 such as
a glass wool sheet, rubber, or plastic is sandwiched between an outer cylinder made of a high
density sound insulation material and an inner cylinder.
[0020]
In the notch on the lower surface side of the vibrating reed 20, a wave receiving sensor 29 is
fixed via a damper. As the wave receiving sensor 29, for example, a piezoelectric acoustic pickup
can be used. Furthermore, a thin pad 30 made of porous paper, cloth, metal woven material or
the like is adhered to the lower surface of the vibrating reed 20 and the lower end face of the
sound absorbing sound insulation cylinder 25.
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[0021]
The power supply 12 basically generates a single pulse current of 0.1 ms or less in time width.
The details of the power supply 12 will be described later.
[0022]
The heavy cone 13 is for bringing the giant magnetostrictive vibration device 11 into close
contact with the search object 101 by its weight. The double cone 13 is not necessarily required,
and the extra-magnetostrictive vibration device 11 may be fixed to the search object 101 using
another tensioning fixture.
[0023]
The arithmetic processing unit 14 includes a sequence control circuit 31, a transmission /
reception signal switching circuit 32, a preamplifier 33, a time difference detection circuit 34, a
vibration wave propagation speed setting unit 35, a distance calculation circuit 36, and an
oscilloscope 37.
[0024]
Hereinafter, the thickness of the object to be searched (for example, porous heterogeneous
material such as concrete, brick, refractory material, soft ceramic, viscoelastic material such as
rubber, soft plastic, etc.) 101 using the searching apparatus of this embodiment A method of
searching for a foreign substance (for example, rebar in concrete) 102 inside the object to be
searched 101 and a defect (void) 103 inside the object to be searched will be described.
[0025]
First, the giant magnetostrictive vibration device 11 is placed on the search object 101.
The giant magnetostrictive vibration device 11 is pressed against the surface of the object to be
searched 101 by the weight of the double cone 13, and the thin pad 30 is in close contact with
the object to be searched 101.
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As a result, no air gap exists between the giant magnetostrictive vibration device 11 and the
object to be probe 101, and vibration waves generated inside the giant magnetostrictive
vibration device 11 are efficiently propagated toward the object to be probe 101. Can. In order to
bring the giant magnetostrictive vibration device 11 into close contact with the object to be
searched 101, a layer of fat, oil, water or the like may be interposed instead of the thin pad 30.
[0026]
Next, a driving current from the power source 12 is applied to the giant magnetostrictive
vibration device 11 brought into close contact with the surface of the object to be searched 101.
As described above, the power supply 12 generates a single pulse current having a time width of
0.1 ms or less as a drive current and supplies it to the exciting coil 16.
[0027]
The exciting coil 16 generates a pulsed magnetic field in response to the pulsed current supplied
from the power supply 12. The giant magnetostrictive material 15 expands normally at a
magnetostriction rate of 0.1% or more when a magnetic field is applied, and returns to its
original state when the magnetic field disappears. That is, the giant magnetostrictive material 15
expands and contracts by the pulsed magnetic field. It is preferable to add a bias current to the
pulse current generated by the power supply 12 for the purpose of improving the linearity of the
magnetostrictive characteristics of the giant magnetostrictive material 15 or the like. The
magnitude of the bias current is set to about 1⁄2 of the pulse current amplitude so that a change
of about 1⁄2 of the operation width of the giant magnetostrictive material 15 occurs. The same
effect can be obtained by applying a magnetic field to the giant magnetostrictive material 15 by
using a permanent magnet instead of the bias current.
[0028]
When the giant magnetostrictive material 15 expands and contracts, the connecting rod 21
connected to the giant magnetostrictive material 15 vibrates in the vertical direction in the
drawing. Thereby, the vibrating reed 20 vibrates. Since the vibrating reed 20 is supported by the
damper 26 around (in the direction perpendicular to the vertical direction in the drawing), it
04-05-2019
8
vibrates only in the vertical direction in the drawing, and the vibration in the vertical direction is
suppressed. Moreover, the vibration in the vertical direction is also absorbed by the damper 24
and is attenuated quickly after the magnetic field disappears. In order to damp the sustained
vibration of the vibrating reed 20 as quickly as possible, it is desirable to reduce the weight of
the vibrating reed 20 as much as possible. In this way, it is possible to obtain a pulse-like
oscillatory wave having a very short duration of 0.2 to 0.5 ms and a small delay with respect to
the excitation pulse current. The frequency of this vibration wave is about 2 to 5 kHz.
[0029]
The vibration wave generated by the vibration of the vibrating reed 20 is transmitted toward the
inside of the search object 101. The propagation speed depends on the search object 101. The
vibration wave transmitted to the object to be probed 101 propagates inside the object to be
probed 101, and the foreign matter 102 inside the object to be probed 101, the defect 103
inside the object to be probed 101, and the bottom surface 104 of the object to be probed 101
Each is reflected.
[0030]
The wave receiving sensor 29 is a vibration wave (transmission signal) generated by the
vibration of the vibrating reed 20 and the foreign substance 102 in the inside of the object to be
searched 101, the defect 103 in the inside of the object to be searched 101, and the bottom
surface 104 of the object The reflected vibration wave (received wave signal) reflected is
received, and the detection signal is output to the transmission / received signal switching circuit
32.
[0031]
The transmission / reception signal switching circuit 32 is controlled by the sequence control
circuit 31, and switching between the transmission operation and the reception operation is
performed.
That is, when the vibration wave is transmitted from the giant magnetostrictive vibration device
11, the sequence control circuit 31 switches the transmission / reception signal switching circuit
32 to the transmission operation time, and the predetermined time (0.1 ms or less) Then, after
the time when it is possible to detect the transmission oscillation wave, the operation is switched
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to the receiving operation. Thereby, the detection signal from the wave receiving sensor 29 is
distinguished into a signal based on the wave transmitting signal and that based on the wave
receiving signal.
[0032]
The detection signal output from the transmission / reception signal switching circuit 32 is
amplified by the preamplifier 33 and input to the time difference detection circuit 34 and the
oscilloscope 37. Here, when there is a large difference in the signal level between the detection
signal based on the transmission signal and the detection signal based on the reception signal,
amplification factors respectively different for the transmission signal and the reception signal in
the preamplifier 33 A switching circuit or the like may be provided so as to perform
amplification.
[0033]
The time difference detection circuit 34 detects the time difference from when the vibration
wave is transmitted to when the reflected vibration wave is received based on the detection
signal from the transmission / reception signal switching circuit 32, and the time difference
signal is used as a distance calculation circuit. Output to 36. The distance calculation circuit 36
determines the thickness of the object 101 to be detected and the distance to the foreign matter
102 based on the propagation velocity of the vibration wave preset in the vibration wave
propagation velocity setting unit 35 and the time difference signal from the time difference
detection circuit 34. , And the distance to the defect 103 are respectively calculated. In addition,
the oscilloscope 37 displays the detection signal from the transmission / reception signal
switching circuit 32 on the CRT screen so that the time difference between transmission and
reception can be visually perceived.
[0034]
In this manner, in the search device of the present embodiment, the thickness of the search
object 101, the distance from the surface to the foreign material 102, and the distance from the
surface to the defect 103 can be determined. In addition, in order to three-dimensionally specify
the positions of the foreign substance 102 and the defect 103 using the search apparatus of the
present embodiment, measurement is performed at at least three places, and the result is
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obtained by calculation processing. Can. In addition, what is necessary is just to obtain | require
the position of the pipe | tube in one cross section, when it is known beforehand embedding |
burying along a fixed direction like an embedded | burying pipe | tube. Therefore, in such a case,
the two-dimensional position of the tube can be determined by measuring in two places. When
measurement is performed using a plurality of search devices at three or two locations, it is
preferable to shift the transmission timings of the plurality of search devices in a time-division
manner in order to prevent interference and the like.
[0035]
As described above, the search apparatus of the present embodiment uses a giant
magnetostrictive material having a magnetostriction rate of 0.1% or more and a large energy
density (25 × 10 3 J / m 3; 20 times or more that of the piezoelectric element). By generating
vibrational waves of large vibrational energy at lower frequencies than in the case of using PZT
(piezoelectric element), it is possible to search for various non-metallic materials which could not
be achieved by a search device using ultrasonic waves. It can be carried out.
[0036]
Next, the power supply 12 will be described in detail.
In the above embodiment, the power source 12 has been described as merely generating a pulse
current, but the current flowing through the exciting coil 16 is delayed in its rise and fall due to
the influence of the self inductance and the like. This delay blunts the waveform of the vibration
wave generated by the giant magnetostrictive vibration device 11 and reduces the resolution in
the search. Therefore, the drive current must be generated by the power supply 12 such that the
current flowing through the exciting coil 16 has a rectangular waveform.
[0037]
Usually, the power supply 12 has a constant voltage source 41 and a transistor 42 connected in
series to the exciting coil 16 and a free wheeling diode 43 connected in parallel to the exciting
coil 16 as shown in FIG. In the power supply 12, when the transistor 42 is turned on and off, a
rectangular wave pulse voltage from the constant voltage source 41 is applied to the exciting coil
16. At this time, the current flowing through the exciting coil 16 is delayed in rising and falling
and does not become a rectangular wave current as shown in FIG.
04-05-2019
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[0038]
In order to make the rising of the current flowing through the exciting coil 16 sharp, a so-called
two-step power supply method may be used. That is, as shown in FIG. 4A, first, a voltage VH
higher than the steady state voltage is applied to the exciting coil 16, and after the current
flowing through the exciting coil 16 reaches a predetermined value, the steady state voltage VL is
applied. You should do it. At this time, the current flowing through the exciting coil 16 has a
sharp rise as shown in FIG. 4 (b).
[0039]
Further, in order to improve the fall of the current flowing through the exciting coil 16, the free
wheeling diode 43 is removed from the circuit of FIG. 2 so that the energy stored in the exciting
coil 16 is consumed by the transistor 42. Good. In this case, an induced voltage control method
using a free wheel diode and a constant voltage diode is employed so that the back electromotive
force generated in the exciting coil 16 does not exceed the collector-emitter withstand voltage
VCEO of the transistor 42. Just do it.
[0040]
FIG. 5 shows a circuit of a power supply 12 adopting a two-step power supply method and an
induced voltage control method. In FIG. 5, when the transistor 51 and the transistor 52 are
turned on, the voltage VH from the high voltage power supply 53 is applied to the exciting coil
16 through the transistor 54 and the resistor 55. Next, when the transistor 51 is turned off while
the transistor 52 is on, the transistor 54 is turned off, so that the voltage VL of the steady-state
voltage source 57 is applied to the exciting coil 16 via the diode 56 and the resistor 55. Ru.
Thereafter, when the transistor 52 is turned off, the energy stored in the exciting coil 16 is
consumed by the transistor 52. At this time, since the back electromotive force generated at the
collector of the transistor 52 is clamped by the free wheel diode 58 and the voltage regulator
diode 59, it does not exceed the collector-emitter withstand voltage VCEO of the transistor 52.
[0041]
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12
The power supply circuit shown in FIG. 2 can obtain only a coil drive current having a time width
of at most 0.5 ms, but the power supply circuit of FIG. 5 can obtain a rectangular drive pulse
current of 0.1 ms or less. Therefore, the resolution of the search apparatus using the power
supply circuit of FIG. 5 is very high as compared with the case of using the power supply circuit
of FIG.
[0042]
In the above embodiment, the vibration wave is transmitted using the vibrating reed 20.
However, as described above, it is desirable to reduce the weight of the vibrating reed 20, and
the surface 101 of the object to be searched is firm. In some cases, the vibrating reed 20 can be
omitted, and the object can be struck directly with the connecting rod 21 to transmit the
vibration wave. However, in this case, the wave receiving sensor 29 is housed in another
container together with the damper 28 and disposed adjacent to the giant magnetostrictive
device 11, and the damper 24 acts between the front lid 19 and the object to be searched 101
And the damper 26 has to act on the side of the connecting rod 21.
[0043]
Next, a second embodiment will be described with reference to FIG. Here, the same components
as those of the first embodiment are denoted by the same reference numerals, and the
description thereof will be omitted. In the search device of the present embodiment, the giant
magnetostrictive material 15 is directly connected to the vibrating reed 20 without the
intervention of the coupling rod 21. In addition, compression springs 23 for applying a pressing
force to the giant magnetostrictive material 15 are uniformly disposed around the yoke 17 (for
example, three pieces form an angle of 120 °) and connected to the base 18 and the vibrating
reed 20 ing. Furthermore, the search device of the present embodiment has a current detector
(not shown) for detecting the current accompanying the transmission and reception flowing
through the excitation coil 16 instead of the reception sensor 29. The current detector may
detect a current flowing through a detection coil provided in addition to the excitation coil 16. In
addition, a delay time difference occurs between the time from when current flows through
exciting coil 16 to the time when the oscillating wave is transmitted, and the time from when the
reflected oscillating wave is received to when the current flows through the coil. Therefore, a
time difference adjustment circuit (not shown) is incorporated in the transmission / reception
signal switching circuit 32. In addition, in the exploration device of the present embodiment, the
tip of the sound absorbing sound insulation cylinder 25 is tapered so as to be easily inserted into
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soil or the like.
[0044]
In addition, the search device of the present embodiment has a plurality of support pieces 61
having one end fixed to the lower end of the inner cylinder of the sound absorbing sound
insulation cylinder 25 and the other end fixed to the vibrating reed 20 and supporting the
vibrating reed 20. ing. The support piece 61 is equally arrange | positioned around the vibrating
piece 20, as shown to Fig.7 (a). Further, strain sensors 62 for detecting strain of the support
piece 61 are provided on the upper surface and the lower surface of the support piece 61,
respectively.
[0045]
Furthermore, the search device of the present embodiment has a brake ring 63 for stopping the
vibration of the vibrating reed 20 and a cover 64 for preventing intrusion of earth and sand. The
brake ring 63 has two ring members, as shown in FIG. 7 (b). The end portions of the ring
members are respectively in pressure contact with the piezoelectric element 72 attached to the
holding seat 71 fixed to the sound absorbing sound insulation cylinder 25. The piezoelectric
element 72 is controlled by a damping control circuit (not shown) connected to the power supply
12 and the strain sensor 62.
[0046]
Next, the operation of the search device of this embodiment will be described. The search device
of the present embodiment is effective in searching for the thickness of soil and the like and the
foreign matter contained therein. Also in the search apparatus of the present embodiment, as in
the first embodiment, the vibrating reed 20 vibrates according to the drive current supplied from
the power source 12 and the vibration wave is transmitted toward the inside of the object to be
searched. . Here, assuming that the drive current supplied from the power source 12 to the
exciting coil 16 is a drive current id as shown in FIG. 8A and the brake ring 63 does not exist, the
vibration displacement Sv of the vibrating reed 20 is It becomes as shown with a broken line in
FIG.8 (b). That is, the vibrating reed 20 performs continuous vibration. Such sustained vibration
must be attenuated quickly in order to make it difficult to receive the reflected vibration wave.
Therefore, in the search device of the present embodiment, the vibration of the vibrating reed 20
04-05-2019
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is converted into the strain of the support piece 61, and the strain is detected by the strain
sensor 62. The output of the strain sensor 62 is input to the damping control circuit. The
damping control circuit causes the voltage to be applied to the piezoelectric element 72 for a
predetermined time (for example, a short time of 0.1 ms or less) when the driving current output
from the power supply 12 becomes less than the predetermined value io after rising once.
Supply. The magnitude of this voltage is made proportional to the detection signal from the
strain sensor 62. The vibration control circuit may control the piezoelectric element 72 only in
response to a change in drive current without using a strain sensor.
[0047]
The piezoelectric element 72 is expanded by energization from the damping control circuit to
press the brake ring 63 against the vibrating reed 20. As a result, the vibration of the vibrating
reed 20 is damped, and its vibration displacement Sv becomes (a pulse mechanical vibration with
a time width of 0.2 ms or less) as shown by a solid line in FIG. 8 (b).
[0048]
The vibration wave generated by the vibration of the vibrating reed 20 is reflected by the bottom
surface of the object to be probed, the foreign matter in the object to be probed, the internal
defect of the object to be probed, etc. This vibration causes a current to flow in the exciting coil
16 due to the inverse magnetostrictive (billing) effect.
[0049]
The current detector detects the current flowing through the exciting coil 16 and outputs the
current to the transmission / reception signal switching circuit 32. The transmission / reception
signal switching circuit 32 adjusts the delay time difference of the input detection signal.
Thereafter, in the same manner as in the first embodiment, the thickness of the object to be
searched, the distance to a foreign object in the object to be searched, and the distance to the
internal defect of the object to be searched are determined.
[0050]
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15
Next, a third embodiment of the present invention will be described with reference to FIG. Also in
this embodiment, the same components as those in the first embodiment are designated by the
same reference numerals and the description thereof will be omitted. In the search apparatus of
the present embodiment, the vibrating reed 20 is divided into two upper and lower pieces, and a
plastic film 91 such as a polyimide film is sandwiched therebetween. The outer peripheral
portion of the plastic film 91 is fixed to the inner cylinder of the sound absorbing sound
insulation cylinder 25 by using a presser 92. Further, the tip of the connecting rod 21 is flat and
in contact with the vibrating reed 20 without being fixed. Further, a first piezoelectric element 93
for detecting the vibration of the vibrating reed and a second piezoelectric element 94 for
damping the vibration of the vibrating reed 20 are provided between the front lid 19 and the
vibrating reed 20. . The first piezoelectric element 93 and the second piezoelectric element 94
are alternately arranged at a predetermined angle as shown in FIG.
[0051]
The exploration device of this embodiment is used for exploration of the depth of a highly
viscous fluid in which the attenuation of ultrasonic waves is large, the embedded foreign matter
in it, and the like. In particular, the present invention is effective for a highly viscous fluid
containing an electromagnetic wave and a highly viscous fluid containing conductive fine
particles.
[0052]
When a pulse drive current (with a time width of 0.1 ms or less) is applied to the exciting coil 16
from the power supply 12, the coupling rod 21 collides with the vibrating reed 20, and the
vibrating reed 20 vibrates. The vibration of the vibrating reed 20 is detected by the first
piezoelectric element 93. The detection output of the first piezoelectric element 93 is output to
the arithmetic processing unit 14 and to a servo amplifier (not shown). The servo amplifier
amplifies the detection output of the first piezoelectric element 93 at a predetermined
amplification factor, and outputs the amplified output to the second piezoelectric element 94.
The second piezoelectric element 94 operates as an active damper that attenuates the vibration
of the vibrating reed 20 by the output of the servo amplifier. If the output of the servo amplifier
is ended in a short time of 0.1 ms or less, the vibration wave can be made into a pulse-shaped
vibration wave having a time width of 0.2 ms or less as in the second embodiment. . Thereafter,
the first piezoelectric element 93 operates as a wave receiving sensor, and based on the output of
the first piezoelectric element 93, as in the first and second embodiments, the thickness or the
04-05-2019
16
like of the object to be searched is searched .
[0053]
In each of the first to third embodiments described above, the pulse current is applied to the
exciting coil 16 to transmit the pulse-like vibration wave. The step-like driving may be performed
with an increase of about 5 ms, and the reception signal of the reflected wave may be detected
while the coil current (displacement of the vibrating reed 20) maintains a substantially constant
value after rising. Specifically, at the time of transmission, the transmission timing can be
detected by differentiating the step-like waveform, and the reception timing can be detected by
separating the incoming wave signal arriving thereafter from the filter or the like. Thus, in the
structure driven by a step-like waveform, the damper for attenuating transmission becomes
unnecessary.
[0054]
According to the present invention, by using the giant magnetostrictive material to vibrate the
vibrating reed, a low frequency, high energy vibration wave can be obtained, which can not be
probed by ultrasonic waves. It is possible to search for objects, heterogeneous materials, and
highly viscous materials, conductive materials that can not be probed by radar, etc.
04-05-2019
17
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