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DESCRIPTION JPH11234797

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DESCRIPTION JPH11234797
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic probe provided in an ultrasonic flaw detector and an ultrasonic diagnostic apparatus
and the like for transmitting and receiving ultrasonic waves.
[0002]
2. Description of the Related Art In order to detect a flaw detection material such as a tube
material or a plate material by an ultrasonic flaw detection apparatus, for example, a so-called
array type probe having a plurality of transducers arranged in an array is opposed to the flaw
detection material. Place the ultrasonic wave from the probe to the flaw detection material while
interposing the contact medium such as water between the probe and the flaw detection
material, and receive the echo by the flaw detection material by the probe, It is determined
whether or not there is an echo related to a defect in the received echo. Moreover, in order to
examine the inside of the living body by the ultrasonic examination apparatus, a jelly-like contact
medium is interposed between the above-described probe and the living body, and the probe is
moved from the probe to the inside while being moved. The ultrasound image is transmitted by
the period of 1, the echoes from the living body are respectively received by the probe, and the
images for medical examination are formed by arranging them in the moving direction of the
probe.
[0003]
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When using such an array type probe, an analog multiplexer, which is a semiconductor switch
group, is interposed between each transducer provided in the probe and a pulse circuit for
applying a pulse to them. By switching the connection between each transducer and the pulse
circuit with the analog multiplexer, it is possible to adjust the aperture value which is the size of
the ultrasonic wave transmitted from the probe.
[0004]
By the way, in the ultrasonic inspection apparatus such as the ultrasonic flaw detector and the
ultrasonic diagnostic apparatus, it is required to improve the inspection sensitivity.
In order to increase inspection sensitivity, it is conceivable to apply a high voltage pulse to each
vibrator. However, since the withstand voltage of the analog multiplexer described above is low,
in order to apply a high voltage pulse to the vibrator, an amplification circuit must be interposed
between the analog multiplexer and each vibrator, so the circuit configuration is It becomes
complicated and the manufacturing cost rises. Therefore, Japanese Patent Application Laid-Open
No. 64-77298 discloses an ultrasonic probe provided with the following layered transducer.
[0005]
FIG. 7 is a front sectional view showing an essential structure of an ultrasonic probe disclosed in
Japanese Patent Application Laid-Open No. 64-77298. In the figure, reference numeral 40
denotes a transducer. The vibrator 40 is provided with a plate-like first electrode 41, and a first
piezoelectric body 51 formed by forming ceramics in a plate shape having a thickness of 190
μm is laminated on the first electrode 41. A U-shaped second electrode 42 is provided on the
first piezoelectric body 51. In the second electrode 42, a second piezoelectric body 52 and a third
piezoelectric body 53 having the same dimensions as the first piezoelectric body 51 are
respectively provided in this order in parallel with the first piezoelectric body 51. A plate-like
third electrode 43 is interposed between the body 52 and the third piezoelectric member 53 so
as to be separated from the second electrode 42. Further, an acoustic matching layer 62 is
stacked on the second electrode 42 and the third piezoelectric member 53 so as to cover them.
The vibrator 40 fixes the first electrode 41 to the rectangular packing member 61 and fixes the
first electrode 41 to the packing member 61.
[0006]
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When ultrasonic waves are transmitted and received by this probe, a DC voltage is applied to the
second electrode 42 and the third electrode 43, and as indicated by arrows in the figure, the
second piezoelectric body 52 and the third piezoelectric body 53 Are polarized in the directions
opposite to each other, and a predetermined DC voltage is applied to the first electrode 41 and
the second electrode 42, and the first piezoelectric body 51 is A process of polarization in the
same direction as the polarization direction of the second piezoelectric body 52 is performed.
[0007]
Then, by applying a pulse to the second electrode 42 and the third electrode 43, the second
piezoelectric body 52 and the third piezoelectric body 53 which are polarized in opposite
directions to each other and electrically connected in parallel are oscillated to generate an
ultrasonic wave. Send
Thus, the electric field strength of the ultrasonic wave can be approximately doubled as
compared with the case where only one of the second piezoelectric body 52 and the third
piezoelectric body 53 is oscillated.
[0008]
Further, by detecting the voltage between the first electrode 41 and the third electrode 43, the
vibration of the first piezoelectric body 51 and the second piezoelectric body 52 which are
polarized in the same direction and electrically connected in series with each other is converted
into an electric signal To receive the echoes from the ultrasound. This suppresses the drop in the
received voltage.
[0009]
SUMMARY OF THE INVENTION However, in the ultrasonic probe disclosed in JP-A-64-77298, it
is difficult to form the piezoelectric body with three or more layers, so that the detection
sensitivity is high. There was a limit to the improvement of
[0010]
The present invention has been made in view of such circumstances, and the object of the
present invention is to laminate a plurality of vibration layers and electrode layers so that each
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vibration layer is sandwiched between the electrode layers, and each vibration layer is The
vibration layers are electrically connected in parallel, and the adjacent vibration layers transmit
ultrasonic waves from the first transducers polarized in opposite directions to each other in the
thickness direction, and the vibration layers are sandwiched by the electrode layers. An object of
the present invention is to provide an ultrasonic probe capable of further improving detection
sensitivity by adopting a configuration in which an echo is received by two transducers.
[0011]
According to a first aspect of the present invention, an ultrasonic probe transmits ultrasonic
waves from a transducer to a test object and receives echoes from the test object by the
transducer. In a probe for detecting an object to be probed, a plurality of vibration layers and
electrode layers are laminated so as to sandwich each vibration layer between the electrode
layers, and the vibration layers are electrically connected in parallel. The vibration layers
adjacent to each other have a first vibrator polarized in the direction opposite to each other in
the thickness direction, and a second vibrator formed by sandwiching the vibration layer with an
electrode layer, from the first vibrator An ultrasonic wave is transmitted to the object to be
detected, and an echo from the object to be detected is received by the second transducer.
[0012]
The first vibrator is electrically connected in parallel with a plurality of vibration layers polarized
in opposite directions to each other in the thickness direction. Therefore, when a pulse voltage is
applied thereto to generate an ultrasonic wave, 1 Compared with the electric field intensity of the
ultrasonic wave generated by applying the same pulse voltage to the vibration layer of the layer,
it is possible to generate the ultrasonic wave of the electric field stronger by the magnification of
the number of the vibration layer.
In addition, since the second vibrator has the vibration layer sandwiched between the electrode
layers, a drop in the echo reception voltage is suppressed.
The number of vibration layers of the first transducer described above can be set to a required
number, and the detection sensitivity can be further improved than the detection sensitivity of
the ultrasonic probe disclosed in JP-A-64-77298.
[0013]
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An ultrasonic probe according to a second aspect of the present invention is characterized in
that, in the first aspect, the first transducer and the second transducer are disposed at different
positions in a direction intersecting the transmission direction of the ultrasonic wave. I assume.
[0014]
The first transducer and the second transducer are disposed at different positions in the direction
intersecting the transmission direction of the ultrasonic wave, so that ultrasonic waves can be
transmitted and received without interference with each other, and the detection sensitivity is
improved. It further improves.
[0015]
An ultrasonic probe according to a third aspect of the present invention is characterized in that,
in the first or second aspect, a plurality of the first and second transducers are provided.
[0016]
Since a plurality of first transducers for transmitting ultrasonic waves are provided, by adjusting
the timing of applying the electric vibration to the first transducers, it is possible to adjust the
aperture value which is the size at which the ultrasonic waves spread.
In addition, by arranging the plurality of second transducers in accordance with the arrangement
of the first transducers, it is possible to find an object to be detected with high detection
sensitivity and high accuracy.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
specifically described below with reference to the drawings.
(First Embodiment) FIG. 1 is a schematic perspective view showing an essential configuration of
an ultrasonic probe according to the present invention, in which 3 is a transmitting transducer
for transmitting an ultrasonic wave, 2, 2, .. Are transducers for receiving echoes.
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The reception transducers 2, 2,... Are arranged so as to be isolated from each other in, for
example, a matrix of approximately 5 × 5, and the transmission transducer 3 is used as a
reception vibration in the center of the matrix instead of the reception transducer. Are provided
in isolation from each other.
[0018]
FIG. 2 is a schematic perspective view showing the receiving vibrator 2 shown in FIG.
As shown in FIG. 2, the receiving vibrator 2 has, for example, Ag70 / Pd30 formed on the front
and back surfaces of a piezoelectric body 22 formed by forming SPEM-5C ceramic (manufactured
by Sumitomo Metal Industries, Ltd.) into a rectangular shape. The electrodes 21 and 21 formed
by forming the alloy of the above in a rectangular plate shape are provided, respectively, and
they are integrally fired.
[0019]
FIG. 3 is a schematic perspective view showing the transmitting vibrator 3 shown in FIG. As
shown in FIG. 3, the transmission vibrator 3 has a plurality of piezoelectric layers 31, 31...
Formed by forming ceramics into a rectangular plate having a thickness of about 20 μm, and a
thickness of 2 to 3 μm. A plurality of electrode layers 32, 32, ... formed by forming into a
rectangular plate having a short side dimension slightly shorter than the short side dimension of
the piezoelectric layer 31 is provided.
[0020]
The piezoelectric layers 31, 31, ... and the electrode layers 32, 32, ... have positions on one long
side of the piezoelectric layers 31, 31, ... and one of the odd-numbered (or even-numbered)
electrode layers 32, 32, ... The positions of the long sides are aligned, and the positions of the
other long sides of the piezoelectric layers 31, 31... And the positions of the even-numbered (or
odd-numbered) electrode layers 32, 32,. .. Are stacked in an alternating rectangular shape, and
the adjacent piezoelectric layers 31, 31,... Are polarized in opposite directions in the thickness
direction. The top and end of this layered body are electrode layers 32 and 32, and acoustic
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matching layers 34 and 34 are formed on both electrode layers 32 and 32, respectively.
[0021]
Rectangular plate-shaped external electrodes 33, 33 are provided respectively on the side and
the other side of the long side of the piezoelectric body layers 31, 31, ... of the layered body. Of
the even-numbered electrode layers 32, 32,... Are connected by the other external electrode 33,
respectively. By this, the piezoelectric layers 31, 31, ... are electrically connected in parallel. The
dimension in the height direction of the transmitting transducer 3 and the dimension in the
height direction of the receiving transducer 2 described above are substantially equal.
[0022]
FIG. 4 is a block diagram showing an essential part of an ultrasonic diagnostic apparatus using
the probe shown in FIG. In the figure, the parts corresponding to those in FIG. A pulse voltage is
applied to the transmission vibrator 3 provided in the probe 1 in a predetermined cycle from the
pulse generation circuit 5, and the transmission vibrator 3 is applied with pulse voltage each
time It is converted into mechanical vibration and ultrasonic waves are transmitted.
[0023]
When echo propagates to a plurality of receiving transducers 2, 2,... Provided in the probe 1, the
receiving transducers 2, 2,. Each of the circuits 6 is given. In the delay circuit 6, the delay time
for delaying the echo signal is preset according to the arrangement position of each of the
receiving transducers 2, 2,. Further, a trigger is given to the delay circuit 6 every time the pulse
generation circuit 5 applies a pulse voltage to the transmission vibrator 3 from the pulse
generation circuit 5 described above.
[0024]
The delay circuit 6 delays the echo signals supplied from the receiving transducers 2, 2,... By the
delay time corresponding to them, and supplies the obtained echo signals to the amplifier 7. The
amplifier 7 amplifies each echo signal supplied from the delay circuit 6 and supplies it to a
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display device 8 provided with a CRT to display an image relating to the echo signal there.
[0025]
When such a probe 1 is used, as described above, a pulse voltage is applied to the transmission
vibrator 3 in which a plurality of piezoelectric layers polarized in opposite directions in the
thickness direction are electrically connected in parallel. To generate ultrasonic waves by
applying the same pulse voltage to one piezoelectric layer, and generate ultrasonic waves of an
electric field stronger by the magnification of the number of piezoelectric layers than the electric
field strength of ultrasonic waves generated by applying the same pulse voltage It can be done.
In other words, the electric field intensity required to generate the ultrasonic waves of the same
intensity can be reduced to one-sixth of the piezoelectric layer. Therefore, an ultrasonic wave of a
required electric field strength can be transmitted without interposing an amplification circuit
with a high amplification factor between the pulse generation circuit 5 and the transmission
vibrator 3, and the circuit configuration is not complicated. The increase of the device cost is
suppressed. Further, since the receiving transducers 2, 2,... Are formed of a single-layer
piezoelectric material, a decrease in the voltage of the echo signal is suppressed.
[0026]
In the present embodiment, the receiving vibrator 2 is formed of a single-layer piezoelectric body
22. However, the present invention is not limited to this, and a plurality of piezoelectric body
layers may be electrically connected in series. It goes without saying that the layers may be
stacked.
[0027]
(Second Embodiment) FIGS. 5 and 6 are schematic plan views showing other embodiments, and
show the case where a plurality of transmitting transducers and a plurality of receiving
transducers are provided on the probe. ing.
As shown in FIG. 5, a plurality of receiving transducers 2, 2,... Are arranged concentrically around
the transmitting transducer 3 around one transmitting transducer 3, and the periphery thereof
Are arranged concentrically as in the previous case, and further, the plurality of receiving
transducers 2, 2,... Are arranged concentrically in the same manner as before. is there.
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[0028]
Further, as shown in FIG. 6, a plurality of transmission transducers 3, 3,... Are arranged
concentrically around the transmission transducer 3 around one transmission transducer 3. A
plurality of reception transducers 2, 2,... Are arranged concentrically around the same as before.
[0029]
In such a probe, by adjusting the timing at which the pulse voltage is applied to the transmitting
transducers 3, 3,..., It is possible to adjust the aperture value to be detected by ultrasonic waves.
[0030]
As described above in detail, in the ultrasonic probe according to the first aspect of the present
invention, the number of vibration layers of the first transducer can be set to a required number,
and the conventional ultrasonic probe The detection sensitivity can be further improved than the
detection sensitivity of
[0031]
In the ultrasonic probe according to the second aspect of the present invention, the first
transducer and the second transducer can transmit and receive ultrasonic waves without
interfering with each other, and the detection sensitivity is further improved.
[0032]
In the ultrasonic probe according to the third aspect of the present invention, by adjusting the
timing of applying the electric vibration to the plurality of first transducers, it is possible to
adjust the aperture value which is the size to which the ultrasonic wave spreads.
In addition, by arranging the plurality of second transducers in accordance with the arrangement
of the first transducers, it is possible to find an object to be detected with high detection
sensitivity and high accuracy.
Furthermore, since the number of wires of the transmission / reception circuit may be set
according to the number of vibrators, the structure of the transmission / reception circuit is
simplified and the number of wires can be reduced as much as possible. Play an effect.
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