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JP2003333694

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DESCRIPTION JP2003333694
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic probe including an array transducer consisting of a plurality of transducer elements.
[0002]
2. Description of the Related Art In an electronic scanning ultrasonic probe, an array transducer
202 is generally bonded onto a backing layer 200 as shown in FIG. It has a configuration in
which the matching layer 204 is bonded thereon. The array transducer 202 has a configuration
in which a plurality of transducer elements (piezoelectric elements) 206 are one-dimensionally or
two-dimensionally arranged, and the grooves 210 between the respective transducer elements
206 are filled with a filler 208. On the other hand, the matching layer 204 has a configuration in
which a plurality of matching elements 214 are arranged. In the matching layer 204, a plurality
of grooves 212 having the same pattern as the groove 210 are formed between adjacent
matching elements 214. The grooves 212 are filled with the same filler as the filler described
above. A ground electrode 220 is provided between the array transducer 202 and the matching
layer 204. Furthermore, in the backing layer 200, there are leads and contact members and the
like for transmitting drive voltages to the respective transducer elements 206 and for extracting
an echo signal, which are omitted in the figure.
[0003]
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1
Each vibration element 206 generates mechanical vibration when a drive voltage is applied, and
transmits ultrasonic waves. Each of the vibration elements 206 transmits ultrasonic waves to a
subject positioned on the upper side in the drawing by longitudinally vibrating mainly along the
stacking direction (Z direction).
[0004]
Here, in order to prevent acoustic crosstalk between the respective vibration elements 206, as
the filler 208, one having an extremely small acoustic impedance as compared to the vibration
elements 206 is used. There is a general correlation between acoustic impedance and stiffness,
and materials with low acoustic impedance generally have low stiffness and are soft. Therefore,
each of the transducer elements 206 fixed on the backing layer 200 vibrates in the lateral
direction, as indicated by, for example, a dashed dotted line or a broken line in FIG. Due to energy
loss due to such unnecessary vibration, for example, problems such as failure to transmit
ultrasonic waves of scheduled acoustic power or deterioration of frequency characteristics and
failure to transmit ultrasonic waves having a scheduled band Happens. In addition, these
problems are the same also at the time of the receiving of an ultrasonic wave, and were causing
the fall of the performance of an ultrasonic probe.
[0005]
On the other hand, in order to suppress this lateral vibration, for example, although it is possible
to use an integral plate-like matching layer in which a groove is not formed instead of the
matching layer 204 in FIG. Since the ultrasonic waves also spread in the matching layer, the
openings of the respective transducer elements 206 become wide, making it difficult to transmit
the ultrasonic waves with an appropriate spread. As a result, it is difficult to widen the scan angle
of the ultrasonic beam in the electronic scan, and the viewing angle in the ultrasonic
measurement becomes narrow.
[0006]
The present invention has been made in view of the above-mentioned problems, and an object
thereof is to provide an ultrasonic probe which enables good mechanical vibration of each
vibrating element.
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2
[0007]
In order to achieve the above object, the present invention provides a backing layer, and a
plurality of vibrating elements provided on the backing layer and having first grooves formed
between the vibrating elements. And a matching layer provided on the array transducer and
having a plurality of matching elements in which a second groove is formed between the
matching elements, and each of the first grooves includes A filler is filled, and each of the second
grooves is filled with a second filler for suppressing unwanted vibration having a composition
different from that of the first filler.
[0008]
Here, the unnecessary vibration of each of the vibration elements is suppressed by using, as the
second filler, a filler having a characteristic of suppressing the unnecessary vibration of the
vibration elements.
[0009]
In a preferred aspect of the present invention, each of the second grooves is a through groove.
Further, in a preferred aspect of the present invention, each of the second grooves is a nonpenetrating groove, and a connecting portion connected to two adjacent matching elements is
formed between the elements of the plurality of matching elements. It is characterized by
Furthermore, in a preferred aspect of the present invention, the connection portion is formed
below the second groove.
Alternatively, the connection portion is formed above the second groove. By providing this
connecting portion, the effect of suppressing unnecessary vibration can be increased. However, it
is desirable to provide the connecting part within a range where the problem of acoustic
crosstalk can be ignored.
[0010]
Also, to achieve the above object, the present invention is an array comprising a backing layer,
and a plurality of two-dimensionally arranged vibrating elements provided on the backing layer
and having first grooves formed between the vibrating elements. A transducer, and a matching
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layer provided on the array transducer and having a plurality of two-dimensionally arranged
matching elements, wherein the matching layer is formed between two adjacent matching
elements in the row direction, And a plurality of second grooves formed between two adjacent
matching elements in the column direction and grid points formed by lattice point portions
surrounded by the corners of the four matching elements, and the corners of the four matching
elements And a connecting part connected to the part, each first groove is filled with a first filler,
and each second groove has a composition different from that of the first filler. The second filler
of the present invention is filled.
[0011]
In a preferred aspect of the present invention, the acoustic impedance of the second filler is
larger than the acoustic impedance of the first filler.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present
invention will be described with reference to the drawings.
FIG. 1 schematically shows the cross section of the main part of the ultrasonic probe according to
the present invention.
The ultrasound probe mainly includes a backing layer 12, an array transducer 14, a ground
electrode 22 and a matching layer 16.
[0013]
The array transducer 14 is a 2D array transducer capable of two-dimensionally electronically
scanning ultrasonic waves, and is configured of a plurality of transducer elements 18 and a first
filler 20.
[0014]
The plurality of transducer elements 18 are two-dimensionally arranged in the Y direction and in
the X direction orthogonal to the Y direction.
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Although five vibrating elements 18 are arrayed in the Y direction in the figure, it is assumed that
the actual array vibrator is an array of vibrating elements 18 in the number corresponding to the
application in the Y direction and the X direction. Configured Each vibrating element 18 is a
minute prismatic piezoelectric element, and electrode films 18 a and 18 b are formed on the
upper side and the lower side, respectively. A single ground electrode 22 is bonded to the upper
side of the plurality of transducer elements 18 and connected to the electrode films 18 a of the
respective transducer elements 18.
[0015]
The respective vibrating elements 18 are formed at predetermined intervals. In other words, first
grooves 24 penetrating the array vibrator 14 in the Z direction are respectively formed between
the adjacent vibration elements 18, and the plurality of first grooves 24 are a plurality of
vibration elements 18. I'm traveling in the shape of a grid between them.
[0016]
Each first groove 24 is filled with a first filler 20. The first filler 20 has, for example, a
composition in which a large number of filler materials are added to a synthetic resin such as
silicone rubber or urethane rubber. Here, in the present embodiment, for example, hollow
bubbles (micro bubbles) having a polymer film as an outer shell are adopted as the filler material.
The acoustic impedance of the first filler 20 is extremely smaller than the acoustic impedance of
the vibrating element 18. As a result, acoustic crosstalk between the vibration elements 18 is
prevented. In addition, since the first filler 20 contains many bubbles, it has low rigidity and is
soft.
[0017]
The backing layer 12 is, for example, a rectangular solid member, and is formed of a synthetic
resin having high rigidity. The backing layer 12 is formed of a material that absorbs ultrasonic
waves emitted downward from the array transducer 14. An array transducer 14 is bonded above
the backing layer 12. The backing layer 12 has a lead, a contact member, and the like for
transmitting a drive signal to each of the above-described transducer elements 18 and extracting
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an echo signal, but these are omitted in the drawing.
[0018]
The matching layer 16 is bonded to the top surface of the array transducer 14. The matching
layer 16 has a plurality of matching elements 26 corresponding to the plurality of vibrating
elements 18 described above. Further, a plurality of second grooves 30 corresponding to the
plurality of first grooves 24 are formed in the matching layer 16, and each second groove 30 is
filled with the second filler 28.
[0019]
These matching elements 26 perform acoustic impedance matching between the subject (living
body) and the vibrating element 18, efficiently transmit ultrasonic waves into the subject, and the
vibrating element reflected waves from the inside of the subject It is formed of a material that
efficiently transmits to 18. The matching element 26 of the present embodiment has, for
example, a composition in which an additive such as silica is added to an epoxy resin or the like.
[0020]
The second filler 28 has a composition different from that of the first filler 20 described above.
Specifically, the second filler 28 is a filler that is stiffer (or harder) than the first filler 20 and has
a larger acoustic impedance than the first filler 20. As the second filler, for example, a synthetic
resin such as silicone rubber or urethane rubber to which no filler agent such as bubble is added
is used.
[0021]
Also, the second filler 28 is used that has a smaller acoustic impedance than the matching
element 26. Incidentally, at this time, the second filler 28 is less rigid (or softer) than the
alignment element 26. That is, the composition of each of the first filler 20, the second filler 28,
and the matching element 26 is adjusted so that, for example, the following relationship is
established.
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[0022]
0 <Za <Zb <Zc (1) 0 <Ga <Gb <Gc (2) where Za, Zb and Zc are respectively the first filler 20, the
second filler 28 and the matching element An acoustic impedance of 26 is shown, and Ga, Gb and
Gc indicate the rigidity of the first filler 20, the second filler 28 and the matching element 26,
respectively.
[0023]
Next, the vibration mode of the vibration element 18 at the time of ultrasonic wave transmission
and reception in the ultrasonic probe of the present embodiment will be described.
[0024]
The lower side of each vibrating element 18 is fixed to the rigid backing layer 12 as described
above.
Therefore, when a drive signal is applied, each vibration element 18 generates mechanical
vibration and performs longitudinal vibration with the lower side fixed.
Thereby, each transducer element 18 transmits ultrasonic waves upward.
[0025]
This can be evaluated by determining the electrical impedance in the equivalent circuit of the
array transducer. For example, in the conventional array transducer 202 shown in FIG. 7, since
the rigidity of the filler 208 around it is low (the acoustic impedance is small), unnecessary
fluctuations exist as shown by the dashed line in FIG. 2 (a). On the other hand, in the present
embodiment (FIG. 1), since the second groove 30 is filled with the second filler 28 with high
rigidity (large acoustic impedance), the movement of the vibrating element 18 (lateral vibration
in FIG. 8) ) Is sufficiently suppressed by the second filler 28 through the electrode film 18a, the
ground electrode 22 and the matching element 26. As a result, as shown by the solid line in the
figure, unnecessary fluctuations do not occur.
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[0026]
Further, when evaluating the directivity angle characteristics of the array vibrator, the angle
formed from the front of the array vibrator 202 becomes large as shown by the broken line in
FIG. 2B in the conventional array vibrator 202. According to, the gain drops sharply and the
directivity narrows. Therefore, the scan angle of the ultrasonic beam can not be made wide. On
the other hand, in the array transducer 14 of the present embodiment, as indicated by the solid
line in the figure, the gain at each directivity angle becomes larger than that of the conventional
one. Therefore, the scan angle of the ultrasonic beam can be broadened, and the viewing angle
can be broadened.
[0027]
Next, referring to FIG. 3, an ultrasonic probe in another embodiment will be described. In
addition, the same code | symbol is attached | subjected to the structure same as the structure
shown by FIG. 1, and the description is abbreviate | omitted.
[0028]
The matching layer 34 bonded to the upper side of the array transducer 14 is composed of a
plurality of matching elements 26, a connecting portion 38 and a second filler 42. The
connecting portion 38 is provided between the adjacent matching elements 26, and is connected
to and connected to two adjacent matching elements 26.
[0029]
Here, the width (thickness) of the connecting portion 38 in the Z direction is smaller than the
thickness of the matching element 26 in the Z direction. In the present embodiment, the
connecting portion 38 is connected on the lower side of each matching element 26, and above
the connecting portion 38, a second groove 40 as a non-penetrating groove having an opening at
the upper side is formed. . The second groove 40 is filled with, for example, a second filler 42
having the same composition as the second filler 28 in the above embodiment.
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[0030]
In the matching layer 34 in the present embodiment, in addition to the composition of the second
filler 42 with respect to the first filler 20, for example, each vibrating element 18 is adjusted by
adjusting the dimensions of the connecting portion 38 such as the thickness of the connecting
portion 38. Control the vibration mode of the Also in this embodiment, the same effect as the
configuration of the above embodiment can be obtained.
[0031]
Furthermore, the ultrasound probe in another embodiment is demonstrated using FIG. The
present embodiment is basically the same as the configuration of FIG. 3 described above except
for the matching layer. Incidentally, the matching layer 44 of the present embodiment is
composed of a plurality of matching elements 26, the connecting portion 38 and the second filler
42, and each of these components itself is each component in the matching layer 34 of FIG. It has
the same configuration as the element.
[0032]
However, the connecting portion 38 is connected on the upper side of each of the matching
elements 26 when connecting to the two adjacent matching elements 26. In the present
embodiment, the connecting portion 38 and each matching element 26 are integrally formed,
and a second groove 46 as a non-penetrating groove having an opening at the lower side is
formed below the connecting portion 38. The second filler 46 is filled in the second groove 46.
Also in this embodiment, the same effect as that of the above embodiment can be obtained.
[0033]
Moreover, the ultrasound probe in another embodiment is demonstrated. Here, in the said
embodiment, it is fundamentally the same except the structure of FIG. 1 mentioned above, and a
matching layer. Here, FIG. 5 partially shows the matching layer 50 of the present embodiment as
viewed from above. The matching layer 50 is composed of a plurality of matching elements 26, a
plurality of second fillers 54, and a plurality of connectors 58. In addition, the same pattern as
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hatching of the 2nd filler 42 in the said embodiment is given to the 2nd filler 54 for convenience.
[0034]
The plurality of matching elements 26 are two-dimensionally arranged in the Y direction (row
direction) and the X direction (column direction) in the same pattern as the arrangement pattern
of the plurality of vibration elements (not shown) arranged below. .
[0035]
Second grooves 56 are formed between the respective matching elements 26.
Here, each second groove 56 in the present embodiment is classified into one of two grooves
described later, that is, an inter-row groove 56a and an inter-row groove 56b.
[0036]
The inter-row grooves 56 a are grooves formed between the respective alignment elements 26
arranged in the row direction, as shown in the figure, and are formed for each two adjacent
alignment elements 26. The figure shows the opening of the groove 56a between the rows
having a rectangular shape. On the other hand, each inter-row groove 56 b is a groove formed
between each of the alignment elements 26 arranged in the column direction, and is formed for
each of two adjacent alignment elements 26. The figure shows the openings of the inter-row
grooves 56b having a rectangular shape.
[0037]
Here, the plurality of inter-row grooves 56a are arrayed in the X direction between the respective
grooves 56a via connecting portions 58 described later, and they are separated from each other
and are independent. The inter-row grooves 56b are also formed in an array in the Y direction
between the grooves 56b via the connecting portions 58. The inter-row grooves 56a and the
inter-row grooves 56b are filled with a second filler 54 having the same composition as the
second filler 28 shown in FIG. The inter-row grooves 56a and the inter-row grooves 56b can be
04-05-2019
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formed by laser processing or the like.
[0038]
The connecting portion 58 is formed for each lattice point portion A surrounded by the corners
60 of the four matching elements 26, and is continuous with the corners 60 of the four elements
26. Each connecting portion 58 connects two sets of matching elements 26 adjacent to each
other in the diagonal direction.
[0039]
FIG. 6 shows a part of the cross section indicated by B-B 'in FIG. As shown in the figure, each
inter-row groove 56b penetrates the matching layer 50 in the Z direction, and is filled with the
second filler 54 as described above. Each connecting portion 58 is a columnar member formed
along the Z direction from the upper side to the lower side of the matching layer 50. The two
adjacent second fillers 54 are separated by the connecting portion 58.
[0040]
The inter-row groove 56a, the second filler 54, and the connecting portion 58 also have the same
arrangement as that of the inter-row groove 56b, the second filler 54, and the connecting portion
58.
[0041]
In the matching layer in the present embodiment, in addition to the composition of the second
filler 54 with respect to the first filler 20, for example, the dimensions of the connecting portion
58 such as the cross-sectional area of the connecting portion 58 are adjusted. The vibration
mode can be well controlled.
Also in this embodiment, the same effect as the main part in the above-described embodiment
can be obtained.
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[0042]
As mentioned above, although the case where the present invention was applied to an ultrasound
probe provided with a 2D array transducer was taken as an example and explained in each
above-mentioned embodiment, it does not restrict to this, for example, 1D array transducer and
1.5D array The present invention can be applied to an ultrasound probe including an array
transducer including a plurality of transducer elements, such as a transducer, as in the above
embodiment, and the same effect as described above can be obtained.
[0043]
According to the present invention, it is possible to provide an ultrasonic probe which enables
good mechanical vibration of each vibration element.
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