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DESCRIPTION JP2000217196

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DESCRIPTION JP2000217196
[0001]
The present invention relates to an array type ultrasonic probe used for medical diagnosis and
nondestructive inspection, a method of manufacturing the same, and a medical ultrasonic wave
using the above array type ultrasonic probe. The present invention relates to a diagnostic device
and a nondestructive inspection device.
[0002]
2. Description of the Related Art Conventionally, in ultrasonic probes used in medical ultrasonic
diagnostic equipment and nondestructive inspection equipment, the piezoelectric longitudinal
effect of piezoelectric ceramic is generally used in order to efficiently transmit and receive
ultrasonic waves. Used for In this case, as a vibration mode of the piezoelectric vibrator, a kt
mode is often used for a single probe, and k33 or k33 'mode is often used for an array probe.
Generally, in piezoelectric ceramic vibrators, the electromechanical coupling coefficient in the kt
mode is about 50%, and the electromechanical coupling coefficient in the k33 and k33 'modes is
about 70%. It is.
[0003]
As a conventional ultrasonic probe, as a technique for improving sensitivity by utilizing the k33
mode, one disclosed in Japanese Patent Application Laid-Open No. 63-252140 is known. As
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shown in FIG. 5, ultrasonic waves are transmitted and received through a composite vibrator in
which a columnar piezoelectric element 19 having a width W to thickness T ratio W / T smaller
than 1 is solidified with an organic compound 20 such as an epoxy resin. It is used as an element,
and the sensitivity is improved by performing longitudinal vibration in each k33 mode of each
columnar ceramic.
[0004]
Also, even in the array-type probe, the condition of W / T <0.6 or less is necessary to favorably
generate the k33 or k33 'mode, and the channel pitch does not satisfy this condition. In the
above, processing such as dividing one channel into several elements is performed.
[0005]
Furthermore, for the purpose of improving sensitivity, piezoelectric ceramics that are ultrasonic
transmitting and receiving elements are laminated, the apparent impedance is reduced, the
electrical matching condition with the drive circuit is improved, the electric field strength applied
to the elements is increased, To improve the transmission sensitivity.
[0006]
However, although the transmission sensitivity is increased according to the number of layers in
the laminated structure, the reception sensitivity is inversely proportional to the number of
layers, and for the purpose of improving the overall transmission / reception sensitivity, for
example, Configurations are known.
As shown in FIG. 6, for example, electrodes are provided on the ultrasonic wave transmitting /
receiving surface and the side surface of a piezoelectric vibrator consisting of a laminate of platelike piezoelectric elements 21 made of piezoelectric ceramic, and the polarization direction 22 of
the piezoelectric elements is partially In the thickness direction and in the radial direction.
According to the above configuration, transmission is performed by applying a voltage to
electrodes provided on the ultrasonic transmission / reception surface to excite thickness
longitudinal vibration in the piezoelectric element, and reception is excited by the mechanical
action of the reflected ultrasonic wave from the object. It is possible to extract the received
voltage by utilizing the radial polarization by utilizing the bending vibration.
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[0007]
SUMMARY OF THE INVENTION The composite vibrator described in JP-A-63-252140 has a
columnar structure formed by cutting a piezoelectric ceramic with a cutter such as a dicer, and
then a cutting groove is formed. Manufactured by filling with an organic material such as an
epoxy resin. Similarly, in the array type probe, division of each channel is performed by a cutting
machine such as a dicer.
[0008]
However, since the transmission and reception frequency of the ultrasonic probe depends on the
thickness of the piezoelectric ceramic, the dimension of the columnar structure or channel pitch
becomes smaller as the frequency becomes higher. Therefore, while the process of machining
with a cutting machine such as a dicer increases, the mechanical strength of the ceramic
decreases, and the characteristic deterioration due to heat or strain at the time of breakage or
processing can not be ignored. There is a problem in that it tends to cause a decrease in yield and
performance degradation. Further, in order to manufacture a piezoelectric vibrator
corresponding to a desired frequency, grinding and polishing of both end surfaces are
indispensable, which is a factor to increase the manufacturing cost.
[0009]
Further, in the configuration described in Japanese Patent Laid-Open No. 7-194517, since the
flexural vibration mode is used at the time of reception, the conversion efficiency is lower than
that using the k33 or k33 'mode, and the structure in the thickness direction Since the
polarization and the polarized portion in the radial direction are divided in the same direction as
the sound wave emitting surface, it is conceivable that the entire surface of the piezoelectric
vibrator can not be used as an ultrasonic wave emitting surface and the sensitivity is lowered.
Furthermore, in the case of deployment to an array-type ultrasound probe, the increase in cost
due to the increase in signal lines becomes a problem.
[0010]
The present invention solves the above-mentioned problems of the prior art, and in particular, in
an array-type ultrasonic probe in which the operation at the time of transmitting and receiving
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the ultrasonic wave is separated, the increase of the signal line is minimized and the sensitivity is
high. It aims at providing an ultrasound probe.
[0011]
In order to solve this problem, the ultrasonic probe in the present invention is a piezoelectric
vibrator having a structure in which plate-like piezoelectric ceramics constituting each channel
are laminated, or a plate-like structure. At least three electrodes are formed on the end face and
inside of a composite piezoelectric vibrator in which a piezoelectric vibrator having a structure in
which piezoelectric ceramics are stacked and a bulk piezoelectric vibrator are stacked, and at
least one different electrode is grounded on transmission and reception. It was configured to be
switched and used.
As a result, it is possible to obtain a high-sensitivity ultrasonic probe which is of the transmission
/ reception separation type while minimizing the increase in the signal line.
[0012]
The invention according to claim 1 of the present invention comprises a plurality of piezoelectric
vibrators having a structure in which plate-like piezoelectric ceramics are stacked, and the abovementioned piezoelectric vibrators are one-dimensionally or two-dimensionally. In the arranged
multi-channel array type ultrasonic probe, at least three electrodes are formed on the end face
and the inside of the piezoelectric vibrator constituting each channel, and the arrangement of the
electrode patterns in the laminated structure is different depending on transmission and
reception The ultrasonic probe is configured to use at least one different electrode as the ground
side electrode at the time of transmission and at the time of reception, and the ground side
electrode is an array type probe. By sharing the respective channels, it is possible to realize a
separate transmission / reception probe without separately providing a switch for each channel
element, and it is possible to increase the number of signal lines. And Hold a has the effect of
obtaining a highly sensitive probe.
[0013]
According to a second aspect of the present invention, in the ultrasonic probe according to the
first aspect, the piezoelectric vibrator has a structure in which two or more types of piezoelectric
ceramics are laminated, and piezoelectric ceramics having different characteristics in
transmission and reception are used. This has the effect of obtaining a more sensitive probe.
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[0014]
The invention according to claim 3 includes a plurality of composite piezoelectric vibrators in
which a piezoelectric vibrator having a structure in which plate-like piezoelectric ceramics are
stacked and a bulk piezoelectric vibrator are stacked, and at least one of the composite
piezoelectric vibrators described above. In the multi-channel array type ultrasound probe
arranged in a plurality of dimensions, at least three electrodes are formed on the end face and
the inside of the composite piezoelectric vibrator, and at least one different electrode is used as a
ground side electrode in transmission and reception By adopting the configuration, it is possible
to realize the transmission / reception separate type probe without providing a changeover
switch for each channel element individually, and to suppress the increase of the signal line and
obtain the high sensitivity probe. Have.
[0015]
The invention according to a fourth aspect is the ultrasonic probe according to the third aspect,
wherein the piezoelectric vibrator has a structure in which two or more types of piezoelectric
ceramics are laminated, and piezoelectric ceramics having different characteristics in
transmission and reception are used. This has the effect of obtaining a more sensitive probe.
[0016]
The invention according to claim 5 is characterized in that, in the ultrasonic probe according to
any one of claims 1 to 4, it has a changeover switch for switching between the ground side
electrode at the time of transmission and the ground side electrode at the time of reception. It is
possible to realize a separate transmission / reception type probe which switches the ground
electrode at the time of transmission and reception with one changeover switch without
separately providing a changeover switch for each channel element, thereby suppressing an
increase in signal lines. And a high sensitivity probe.
[0017]
The invention according to claim 6 comprises a plurality of piezoelectric vibrators having a
structure in which plate-like piezoelectric ceramics are laminated, and the above-mentioned
piezoelectric vibrators are arranged at least one-dimensionally in a multichannel array type
ultrasonic probe. In the second embodiment, a piezoelectric ceramic having different thickness
between electrodes in the same laminating step is provided without separately laminating bulk
piezoelectric vibrators by forming a portion where the plate-like piezoelectric ceramic is
laminated without forming electrodes. By producing a piezoelectric vibrator having a layer, it has
the effect of reducing the cost and obtaining a highly sensitive ultrasonic probe with less
individual differences.
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[0018]
The invention according to claim 7 or 8 is a medical ultrasonic diagnostic apparatus or
nondestructive inspection apparatus characterized by having the ultrasonic probe according to
any one of claims 1 to 6, It has an effect of obtaining a medical ultrasonic diagnostic apparatus or
a nondestructive inspection apparatus having a high sensitivity probe utilizing the respective
features 1 to 6.
[0019]
The invention according to claim 9 is a process of forming the piezoelectric vibrator by
laminating plate-like piezoelectric ceramics so that at least three electrodes are formed on the
end face and inside of the piezoelectric vibrator, and the piezoelectric vibrator Forming an
external electrode on an end face and a side face of the piezoelectric vibrator so as to be
electrically connected to an electrode formed in the inside of the piezoelectric vibrator,
performing a polarization process on the piezoelectric vibrator, and Bonding the matching layer
and the backing material to the end face and the opposing end face, and forming a cutting groove
extending from the matching layer to the backing material so as to constitute a preset number of
channel elements It is a method of manufacturing an ultrasonic probe characterized in that the
channels are easily formed by collectively cutting the piezoelectric vibrator and the electrode
when forming the respective cutting grooves. In addition, by making the ground side electrode
common to each channel constituting the array type probe, it is possible to realize the
transmission / reception separate type probe without separately providing each channel element.
It has an effect of suppressing an increase in signal lines and obtaining a highly sensitive probe
by a simple manufacturing method.
[0020]
The invention according to claim 10 is the ultrasonic probe manufacturing method according to
claim 9, wherein the external electrode is a signal electrode for inputting and outputting an
ultrasonic transmission / reception signal, and a transmission ground electrode for grounding
upon transmission. The method is a manufacturing method characterized in that it is a receiving
ground electrode that is grounded at the time of reception, and different ground side electrodes
that are different at the time of transmission and at the time of reception are commonly
configured in each channel constituting the array type probe. By doing this, it is possible to
realize a separate transmission / reception type probe without providing a changeover switch for
each channel element individually, and a probe having high sensitivity and suppressing an
increase in signal lines by a simple manufacturing method. Have the effect of obtaining
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[0021]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to
4.
[0022]
(Embodiment) FIG. 1 is a perspective view of an array-type ultrasonic probe according to an
embodiment of the present invention.
Moreover, FIG. 2 is sectional drawing of the short axis direction of the piezoelectric vibrator
which comprises the array type ultrasonic probe of this Embodiment.
In FIG. 1, 1 is an ultrasonic probe, 2 is a transmitting piezoelectric element, 3 is a receiving
piezoelectric element, 4 is an external electrode, 5 is a backing material, 6 is a cutting groove,
and 7 is a piezoelectric vibrator.
Further, in FIG. 2, 8 indicates a signal electrode, 9 indicates a transmission ground electrode, 10
indicates a reception ground electrode, and 11 indicates a polarization direction.
Moreover, FIG. 3 is a figure which shows the manufacturing process of the ultrasound probe in
embodiment of this invention.
[0023]
Hereinafter, an example of a method of manufacturing an ultrasonic probe according to the
embodiment of the present invention will be described with reference to FIGS. 1 to 3.
First, the piezoelectric vibrator 7 is manufactured.
As shown in FIG. 2, the piezoelectric vibrator 7 has a structure in which the transmitting vibrator
2 and the receiving piezoelectric element 3 are stacked.
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The transmitting piezoelectric element 2 has a sandwich structure of a thin piezoelectric thin
plate and an electrode layer.
Such a structure can be produced, for example, by laminating and integrally sintering a
piezoelectric ceramic green sheet on which electrodes are printed and formed using platinum
paste or the like before firing.
The green sheet can easily have a thickness of 100 μm or less, and the thickness of each layer
can be arbitrarily set according to the presence or absence of the electrode.
The receiving piezoelectric element 3 can be manufactured by laminating green sheets in the
same manner as the transmitting piezoelectric element 2. In that case, the portion of the
receiving piezoelectric element 3 can be formed by laminating only the green sheets without the
printing step of the electrode layer. In the above manufacturing process, the piezoelectric
vibrator 7 can be integrally manufactured by forming and sintering the transmitting piezoelectric
element 2 and the receiving piezoelectric element 3 in a green sheet state.
[0024]
In this case, the piezoelectric vibrator 7 can be manufactured by selecting the thickness and the
material of each laminated structure in consideration of the transmission / reception sensitivity
characteristics of the piezoelectric element material and the input / output impedance of the
driving or receiving circuit. Therefore, the transmission piezoelectric element 1 and the reception
piezoelectric element 2 may be made of different materials. Alternatively, only the transmitting
piezoelectric element 2 may be fired and manufactured by a lamination method of green sheets,
and the receiving piezoelectric element 3 may be bonded by using one which is sintered in bulk
and processed to a predetermined thickness by polishing or the like.
[0025]
After the piezoelectric vibrator 7 is manufactured as described above, as shown in FIG. 3, the
external electrode 4 for conduction with the internal electrode of the piezoelectric vibrator 7 is
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made of silver paste, baked silver, etc. The radiation electrode is formed on the end face and the
side opposite to the radiation face, and the signal electrode 8, the transmission ground electrode
9, and the reception ground electrode 10 shown in FIG. 2 are formed. Thereafter, polarization
processing is performed in the polarization direction 11 as shown in FIG. 2, and a plurality of
signal lines (not shown) for forming the elements of the array transducer of the piezoelectric
vibrator 7 are connected to the signal electrodes 8, The first matching layer 12, the second
matching layer 13, and the backing material 5 are joined using a method such as adhesion.
Thereafter, the ultrasonic probe 1 is formed by forming the cutting groove 6 from the second
matching layer 13 to the backing material 5 using a dicer or the like to separate each channel
element.
[0026]
Although not shown in FIG. 1 or FIG. 3, it is also conceivable to bond an acoustic lens to the
second matching layer 13. Also, although the matching layer here has a two-layer structure,
there may be more layers depending on the subject, or there may be one layer or no matching
layer.
[0027]
The operation of the ultrasound probe according to the embodiment of the present invention will
be described with reference to FIG. In FIG. 4, 14 is a changeover switch, 15 is a signal line, 16 is
a transmission ground line, 17 is a reception ground line, 18 is an ultrasonic wave, (a) is a wiring
at transmission, and (b) is reception The wiring at time is shown. As shown in FIG. 4, at the time
of transmission, the changeover switch 14 is connected to the electrode 9 via the transmission
ground line 16. A signal such as a high voltage pulse or a burst is supplied from the signal line
15 to the transmission piezoelectric element 2. In the case of the pulse echo mode, the
piezoelectric vibrator 7 excites the resonance vibration of the entire thickness mode by the
driving pulse applied to the transmitting piezoelectric element 2 and transmits the pulsed
ultrasonic wave 18 toward the subject. . At the time of reception, the changeover switch 14 is
connected to the reception ground electrode 10 via the reception ground line 17. The ultrasonic
wave 18 reflected from the object passes through the transmitting piezoelectric element 2 to
reach the receiving piezoelectric element 3 and is converted into an electric signal, and then
transmitted to the receiving circuit of the main body through the signal line 15.
[0028]
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Unlike the signal line, the ground side electrode can be commonly provided to the elements
constituting the array, so that it is not necessary to provide a changeover switch for each
element, so it is necessary to provide a complex electronic circuit inside the probe. Absent. Also,
the increase in signal lines can be minimized. Although only one changeover switch is shown in
FIG. 4, several switches may be used in the case where it is necessary to divide the ground into a
plurality of parts in order to prevent noise.
[0029]
As described above, according to the embodiment of the present invention, it is possible to
realize a high sensitivity ultrasonic probe of the transmission / reception separation type while
minimizing the increase in signal lines and electronic circuits to be added.
[0030]
Furthermore, by using the above-described ultrasonic probe, it is possible to realize a highly
sensitive medical ultrasonic diagnostic apparatus or a nondestructive inspection apparatus with
reduced cost.
[0031]
As described above, according to the present invention, there are provided a plurality of
piezoelectric vibrators having a structure in which plate-shaped piezoelectric ceramics are
laminated, and a multi-channel array type in which the above-mentioned piezoelectric vibrators
are arranged in at least one dimension. In the ultrasonic probe, at least three electrodes are
formed on the end face and the inside of the piezoelectric element constituting each of the abovementioned channels, and at least one different electrode is used as a ground side electrode in
transmission and reception. It is possible to realize a high sensitivity ultrasonic probe of the
transmission / reception type while minimizing the increase in the number of electronic circuits.
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