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JPH02307056

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DESCRIPTION JPH02307056
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic probe provided with an acoustic lens for focusing ultrasonic waves. [Prior Art] An
ultrasonic inspection apparatus for inspecting the presence or absence of a defect on the surface
or inside of an object, or for inspecting the shape of the object surface using an ultrasonic wave,
the surface structure of the object, the surface state, etc. using an ultrasonic wave Ultrasonic
microscopes for measuring are generally well known. An ultrasonic probe is used for the
ultrasonic inspection apparatus and the ultrasonic microscope, and the ultrasonic probe
generates an ultrasonic wave and reflects the reflected wave from the object of the ultrasonic
wave according to the reflected wave. Convert to an electrical signal. That is, an ultrasonic probe
generally comprises a piezoelectric element and an acoustic lens, and an ultrasonic wave
generated by excitation of the piezoelectric element is focused by the acoustic lens and emitted
to the object, and a reflected wave from the object passes through the same path and is
piezoelectric Returning to the element, the piezoelectric element is vibrated to output an
electrical signal. When inspecting or measuring an object using ultrasonic waves as described
above, it is generally preferable to interpose a liquid (for example, water) between the object and
the ultrasonic probe by arranging the object and the ultrasonic probe in the liquid. It is.
[Problems to be solved by the invention] By the way, the higher the frequency of the ultrasonic
wave, the higher the resolution of the reflected wave signal can be obtained, but on the other
hand, the higher the frequency, the larger the attenuation of the ultrasonic wave in the object is.
It has a characteristic. Therefore, when actually performing an inspection or measurement with
ultrasound, first use an ultrasound probe of a certain frequency, and if the reflection signal at the
target position of the object is sufficiently large, use the ultrasound probe used. Convert to a
higher frequency ultrasound probe to obtain higher resolution, and conversely, if the reflected
signal at the target position is too small, then use the ultrasound probe at the expense of
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resolution The task is to replace the low frequency ultrasound probe. For this reason, it is not
only necessary to prepare a plurality of ultrasound probes with different frequencies in
inspection and measurement, but also it takes a lot of labor and time to determine an optimal
ultrasound probe. There was a problem. In ultrasonic inspection and measurement, the reflected
signal may be frequency analyzed to extract information of a specific frequency component. In
this case, it is natural to use an ultrasonic probe at or near the specific frequency. Therefore, also
in such a case, as described above, it is necessary to prepare a plurality of probes having
different frequencies, and there has been a problem that it takes time and effort for its removal
and attachment.
SUMMARY OF THE INVENTION The object of the present invention is to solve the problems in
the above-mentioned prior art, to cope with various inspections and measurements without
preparing a plurality of ultrasonic probes, and it takes time and effort for replacement. An object
of the present invention is to provide an ultrasonic probe that can be omitted. [Means for Solving
the Problems] In order to achieve the above object, according to the present invention, an
ultrasonic wave transmitting / receiving unit for generating an ultrasonic wave and receiving the
reflected wave, and an ultrasonic wave generating unit provided in contact with the ultrasonic
wave transmitting / receiving unit In the ultrasonic probe constituted by an acoustic lens for
focusing the generated ultrasonic waves, the ultrasonic wave transmitting / receiving unit
comprises: a single piezoelectric element of cylindrical shape and its electrode; and at least one of
the piezoelectric element arranged around the piezoelectric element The present invention is
characterized in that it is configured as two ring-shaped piezoelectric elements and their
electrodes, and the oscillation frequencies of these respective piezoelectric elements are selected
to different predetermined frequencies. [Operation] When inspecting or measuring a certain
object, one of the multiple piezoelectric elements is selected to emit an ultrasonic wave, and the
reflection signal is observed. If not appropriate, the other piezoelectric elements are used. select.
These choices are achieved simply by switching the electrodes. Further, in the case of inspection
or measurement for extracting a specific frequency component of the reflected wave signal, it is
only necessary to select one of the piezoelectric elements having a frequency close to the specific
frequency. r Embodiment] The present invention will be described based on the illustrated
embodiment. FIG. 1 (a) is a plan view of an ultrasonic wave transmitting / receiving unit of an
ultrasonic probe according to an embodiment of the present invention, and FIG. 1 (b) is a cross
section along line 1b-Ib shown in FIG. 1 (a) FIG. In each figure, 1 is a cylindrical piezoelectric
element of thickness T, IE is its upper electrode, 2 is a piezoelectric element of ring T with
thickness Tt, 2E is its upper electrode, 3 is thick A piezoelectric element formed in a ring shape
with a length T3, 3E is an upper electrode thereof, 4 is a piezoelectric element formed in a ring
shape with a thickness T, and 4E is an upper electrode thereof. E is a common electrode
commonly provided on the lower surface of each of the piezoelectric elements 1 to 4. The
piezoelectric elements 1 to 4 are made of the same material, and adjacent ones are closely
arranged to each other. The ultrasonic transmitting and receiving unit 5 is configured by the
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piezoelectric elements 1 to 4 and the electrodes IE to 4E and E. When the piezoelectric elements
are made of the same material, the frequency of the generated ultrasonic wave is lower as the
thickness is larger. Therefore, the frequency of the piezoelectric element 1 is the lowest, and the
frequency of the piezoelectric element 2.3.4 increases in that order. 2 and 3 are a cross-sectional
view and a side view of an ultrasound probe according to an embodiment of the present
invention, respectively.
In each figure, 5 is an ultrasonic wave transmitting / receiving unit shown in FIGS. 1 (a) and 1 (b),
and 7 is a housing. The ultrasonic transmitting and receiving unit 5 is housed in the housing 7.
An acoustic lens 8 housed in the housing 7 is provided in contact with the lower portion of the
common electrode E of the ultrasonic wave transmitting / receiving unit 5. The acoustic lens 8 is
formed of a material such as quartz or polyester, and has a function of converting an ultrasonic
wave generated by each of the piezoelectric elements 1 to 4 into an ultrasonic beam B I ? ? ?
B a focused as indicated by a broken line. . A damper material 9 absorbs and attenuates the
sound of the upper surface (the rear surface on the output side) of the ultrasonic transmitting
and receiving unit 5, and an epoxy resin mixed with tungsten powder, for example, is used. The
ultrasonic transmitting and receiving unit 5 is molded in the damper material 9. IO is each
electrode IE-4E of the ultrasonic transmission / reception part 5. Switch box into which the lead
wire connected to the rod is introduced, 11 is a plug for connecting with a balser receiver (not
shown) via a probe cable (not shown), 12 is an inspection or measurement Indicates the target
object of The lead wire connected to the common electrode E is introduced into the switch box
10 and then connected (grounded) to the mounting portion 11 by the lead wire. The switches S
and S4 are switches provided in the switch box 10, and connect and disconnect the upper
electrodes IE-4E from the balsa receiver not shown. Now, for example, when only the switch S3 is
switched to the ON side and a pulse is output from a balsa not shown in this state, this pulse is
applied between the upper electrode 3E and the common electrode E, and the piezoelectric
element 3 is excited to generate an ultrasonic wave. This ultrasonic wave is focused from the
acoustic lens 8 into a focused ultrasonic beam B3 and is reflected by the object 12 back in the
same path to reach the piezoelectric element 3 to vibrate it. A voltage (reflected signal)
corresponding to the reflected ultrasonic wave is generated between the upper electrode 3E of
the piezoelectric element 3 and the common electrode E, and this reflected signal is transmitted
to the receiver (not shown) via the switch S3 and then given. Processing is performed. The
operator looks at the processing result and turns off the switch S and turns on the switch S4 to
select the piezoelectric element 4 having a higher frequency, in order to obtain a signal with a
higher resolution. Also, in view of the processing result, when the magnitude of the reflection
signal at the target position in the object 12 is not sufficient, the switch S3 is set to OF'F and the
switch S2 or switch S1 is turned on to lower the frequency piezoelectric element 2 or
piezoelectric element Select 1 As described above, in the present embodiment, a plurality of ringshaped piezoelectric elements are disposed adjacent to each other around one cylindrical
piezoelectric element to constitute an ultrasonic wave transmitting / receiving unit, and the
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thicknesses of the respective piezoelectric elements are made different. Since the oscillation
frequencies are different from each other, it is not necessary to prepare a plurality of ultrasonic
probes, and at the time of ultrasonic inspection or measurement, it is not necessary to take time
and effort for the piezoelectric element suitable for the inspection or measurement. It can be
easily selected without time.
In addition, inspection and measurement of various objects can be handled by one ultrasonic
probe. Furthermore, since the high-frequency piezoelectric elements are sequentially disposed
around the low-frequency piezoelectric element on the outer periphery thereof, the incident
angle of the ultrasonic beam from the piezoelectric element at the central portion to the object
becomes smaller, and the attenuation is reduced. In combination with the low frequency
characteristics of small size, inspection and measurement inside the object can be performed
more effectively, and the incident angle of the ultrasonic beam from the piezoelectric element in
the outer peripheral part to the object becomes large. , Inspection and measurement of object
surface and surface layer can be performed more effectively. In the description of the above
embodiment, the piezoelectric element having the lowest frequency is taken as a center, and the
other piezoelectric elements are arranged around the piezoelectric element so that the frequency
becomes higher sequentially. The arrangement of can be arbitrarily selected in consideration of
various conditions. Further, as the piezoelectric element, it is also possible to use different
materials instead of the same material. [Effects of the Invention] As described above, in the
present invention, since the transmitting and receiving unit is constituted of piezoelectric
elements of a plurality of different frequencies, it is not necessary to prepare a plurality of
ultrasonic probes, and one ultrasonic wave is required. The probe can cope with inspection and
measurement of various objects, and inspection and measurement can be performed with a
piezoelectric element of an appropriate frequency without requiring any labor and time.
[0002]
Brief description of the drawings
[0003]
1 (a) and 1 (b) are a plan view and a cross-sectional view of an ultrasonic transmitting and
receiving unit of an ultrasonic probe according to an embodiment of the present invention, and
FIGS. 2 and 3 relate to an embodiment of the present invention. It is sectional drawing and a side
view of an ultrasonic probe.
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1-4 и и и и и и Piezoelectric element, IE ~ 4 E, E и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и и ultrasonic
wave transmitter and receiver unit, 8 и и и и и и и acoustic lens, 10 и и ииииииии Switch box, SI ~ S4 иииииии
Switch 18th-4: Piezoelectric Yonago / E-4E, E: @ jf n 'j 15: Acoustic wave difference receiving part
Fig. 8: Acoustic lens ░ "LO: switch box Fig. 3
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