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JPH09191497

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DESCRIPTION JPH09191497
[0001]
The present invention relates to an array type ultrasonic probe having an acoustic lens
(hereinafter referred to as an array type probe) as a technical field, and in particular, to suppress
unnecessary ultrasonic waves from the outer periphery of the acoustic lens. And an arrayed
probe having a narrow beam width (see: Japanese Patent Application Nos. 7-48978 and 7203788).
[0002]
BACKGROUND OF THE INVENTION Arrayed probes are useful as ultrasound transducers, for
example in medical ultrasound diagnostic devices. For example, strip-shaped small width
piezoelectric elements are arranged in the width direction (long axis direction), and linear or
sector drive is performed in the same direction. In such a device, in general, an acoustic lens is
provided in the longitudinal direction (short axis direction) of the piezoelectric element,
ultrasonic waves are converged, and transmission and reception are performed to enhance
resolution in the same direction.
[0003]
“An example of the prior art” FIG. 5 is a diagram of an array-type probe for explaining this
kind of conventional example, and FIG. 5 (a) is a schematic front sectional view, FIG. 5 (b) is a
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side sectional view, FIG. The figure (c) is a figure of an acoustic lens. The arrayed probe is formed
by arranging strip-shaped piezoelectric elements 2 made of PZT (lead zirconate titanate) or the
like on the backing material 1 in the long axis direction. Electrodes are provided on both main
surfaces, and a filler is embedded between the grooves (not shown). Then, on the front surface of
the piezoelectric element 2, a two-layer acoustic matching layer 3 (ab) is provided to measure the
matching of the acoustic impedance with the detection target (such as a living body) and to
improve the ultrasonic wave propagation efficiency. Furthermore, an acoustic lens 4 is provided
on the acoustic matching layer 3. The piezoelectric element group is provided with a flexible
substrate or the like (not shown) connected to the electrodes of each piezoelectric element 2, and
a mold layer 5 is applied to the outer periphery thereof. Reference numeral 6 in the figure is a
base, and 7 is a case.
[0004]
The acoustic lens 4 may basically be provided on the acoustic matching layer 3 with a length
equal to that of the piezoelectric element 2 as shown in FIG. However, in reality, in order to
prevent displacement or detachment of the acoustic lens 4 with respect to the piezoelectric
element 2, the leg portion 4b is provided on the outer periphery of the lens portion 4a (FIG. 5
(bc)). The sound velocity is convex when it is slower than the detection target (living body), and
concave when it is faster.
[0005]
Then, for example, as shown in FIG. 7, the lens molding die 10 is used to make it. The lens
molding die 10 is composed of a concave first die 8 having a curvature and a second die 9 having
a convex shape. The first mold 8 and the second mold 9 have a space 11 corresponding to the
acoustic lens 4 between them. Then, a silicon-based resin is injected between the first mold 8 and
the second mold 9 and press-formed.
[0006]
Also, in general, the acoustic lens 4 (length L of the lens portion 4a) is set in advance to be large,
and is also applied to the smaller piezoelectric element 2. The reason is that, since the curvature
of the lens portion 4a is the same, if the length L of the piezoelectric element 2 is constant, it
basically has the same focal point F as shown in FIG. 8 (ab) ( However, since the thickness is
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increased, the attenuation of ultrasonic waves is increased). In this way, the versatility of the
acoustic lens 4 is enhanced, and the molding die 10 does not have to be manufactured each time.
In addition, the production of the first mold 8 having a curvature requires a very high level of
technology, resulting in an increase in the production cost.
[0007]
[Problems to be Solved by the Invention] [Problems of the Prior Art] However, in the array type
probe having the above-mentioned configuration, ultrasonic waves emitted from both ends of the
acoustic lens 4 as the accuracy of the diagnostic device and the like increases. However, it has
recently been found that the beam width is broadened and the resolution etc. is adversely
affected. That is, the acoustic lens 4 is set to be larger than the length of the piezoelectric
element 2 as described above. For this reason, it has been found that the ultrasonic wave
particularly propagates in the lens portion 4a and leaks from the outer periphery of the acoustic
lens 4, and the beam width of the ultrasonic wave is broadened (see FIG. 9).
[0008]
[Problems of the Invention and Purposes] The present invention solves the problem of ultrasonic
wave leakage from the end of the acoustic lens and manufacture of the acoustic lens excellent in
versatility, and the problem is to solve, and the resolution is excellent. It is an object of the
present invention to provide a method of manufacturing an array type probe and an acoustic
lens.
[0009]
SUMMARY OF THE INVENTION In the present invention, a leg extending from the outer
periphery of a lens section is formed by making the lens section of an acoustic lens placed on a
piezoelectric element group equal to or less than the length of the piezoelectric element. An
ultrasonic wave shield that is separate from the lens unit is used, and the lens unit and the leg
unit are integrated as a first solution.
[0010]
In addition, as a method of manufacturing such an acoustic lens, a step of forming a leg between
the concave first mold and the convex second mold having the curvature, and a process of
forming a lens part , And integrating the lens unit and the leg unit as a second solution means.
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[0011]
In the first solution means of the present invention, since the leg portion is an ultrasonic shield
with the lens portion equal to or less than the length of the piezoelectric element, ultrasonic wave
leakage from the outer periphery of the acoustic lens is prevented. .
In addition, since the lens portion and the leg portion are integrated as separate members, there
is an effect of making the lens portion common.
[0012]
Further, in the second solution, since the step of forming the leg portion and the step of forming
the lens portion are separated, the function of making it possible to control the length of the lens
portion using the same first mold. There is.
Hereinafter, each example of the present invention will be described.
[0013]
[First Embodiment] FIG. 1 is a view for explaining an embodiment corresponding to the first
solution means of the present invention, wherein FIG. 1 (a) is a sectional view of an array type
probe, and FIG. 1 (b) is an acoustic lens. Of the
The same reference numerals are given to the same parts as in the prior art example and the
description will be simplified. The arrayed probe is formed by arranging the piezoelectric
elements 2 on the backing material 1 to form the acoustic matching layer 3 (ab) and providing
the acoustic lens 4 as described above. The acoustic lens 4 in this embodiment is composed of
the lens portion 4a and the side plate 4c (corresponding to the leg portion 4b described above).
The lens portion 4a is convex as described above and is made to conform to the length of the
piezoelectric element 2, and is made of, for example, a silicon material having a lower sound
velocity than a living body. The side plate 4c has a bowl shape and is connected to the outer
peripheral end face of the lens portion 4a, and is made of, for example, a polyimide resin
different in acoustic impedance from the lens portion 4a. And both are joined and integrated by
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an adhesive agent or thermocompression bonding etc.
[0014]
As described above, in the present embodiment, after the lengths of the piezoelectric element 2
and the lens portion 4a are made equal, side plates 4c having different acoustic impedances are
provided on the outer periphery of the lens portion 4a. Accordingly, since the acoustic
impedances of the lens portion 4a and the side plate 4c are different from each other, the
ultrasonic waves are reflected to prevent the propagation into the side plate 4c. That is, the side
plate 4c functions as an ultrasonic wave shield. From this, the leak of the ultrasonic wave from
the outer periphery of the acoustic lens 4 is prevented. Therefore, the spread of the beam width
is prevented and the resolution is improved.
[0015]
Further, since the lens portion 4a and the side plate 4c are separately joined, the lens portion 4a
may be set large beforehand and cut in accordance with the length of the piezoelectric element 2.
Therefore, it is not necessary to manufacture the above-mentioned 1st metal mold | die 8
according to the length of the lens part 4a whenever the length of the piezoelectric element 2
differs. From this, the versatility of the acoustic lens 4 is increased without increasing the cost.
[0016]
[Second Embodiment] FIG. 2 is a schematic view of a mold for explaining an embodiment
corresponding to a method of manufacturing the second solution in the present invention. The
acoustic lens 4 is formed using the molding die 10 as described above. In this embodiment, the
second mold 9a is formed in a convex shape having a step at its tip. Then, the end corner portion
of the second mold 9a is abutted against the concave surface having the curvature of the first
mold 8 to form a bowl-like space corresponding to the side plate 4c. Next, a molten polyimide
resin is injected into the bowl-like space from the unshown holes 12a of the first mold and
solidified to form the side plate 4c. Then, the second mold 9a is removed, and rubber-like silicon
is injected into the concave space. Next, the injected silicon is pressed by the third mold 9b which
is simply convex, and the lens portion 4a is formed and integrated with the side plate 4c. In
addition, at the time of pressing, a surplus of silicon is formed to protrude from between the first
mold 8 and the third mold (the side plate 4c).
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[0017]
With such a manufacturing method, the length of the lens portion 4a can be controlled by
changing the thickness of the side plate 4c with the second mold 9a while keeping the length of
the concave surface of the first mold 8 constant. . Therefore, the first mold 8 can be shared, and
an inexpensive and versatile acoustic lens 4 can be manufactured. And since the leg part 4c is
made into an ultrasonic shielding body as mentioned above, the leak of the ultrasonic wave from
the outer periphery of the acoustic lens 4 is prevented.
[0018]
[Other matters] In the above embodiments, the side plate 4c of the acoustic lens is shaped like a
bowl, but there is no mold layer or the like 5 on the outer periphery or it is very thin. In this case,
the side plate 4c may simply be a flat plate (FIG. 3).
[0019]
Further, although the lens portion 4a is made to match the length of the piezoelectric element 2,
the length of the lens portion 4 may be shorter than that of the piezoelectric element 2 to
provide the side plate 4c having a hook shape.
In this case, since the ultrasonic wave is shielded by the side plate 4c, the lens portion 4a
becomes substantially the length of the piezoelectric element 2 (the opening length of the
ultrasonic wave) [FIG. 4]. In this case, the ridges of the side plate 4c are located on the upper
surfaces of both ends of the piezoelectric element 2, and ultrasonic waves from the piezoelectric
element are directly propagated. Therefore, for example, a foamed resin in which bubbles are
contained in a polyimide resin may be used, and the shielding may be made more complete by
the bubbles.
[0020]
In the second embodiment, after injecting and solidifying the polyimide resin to be the side plate
4c, silicon to be the lens portion 4a is injected, but conversely, the second metal mold 9 etc.
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Alternatively, after the lens portion 4a, a resin to be the side plate c may be injected and formed.
Furthermore, the side plate 4c may not be formed by injection, and the side plate 4c formed in
advance may be provided on the inner periphery of the first mold 8 or the outer periphery of the
second mold by an adhesive or the like. Further, as described above, the resin to be the side plate
4c may be a foam resin of mixed air bubbles in order to enhance the shielding effect. The side
plate 4c is not limited to polyimide, but may be silicon mixed with air bubbles, and basically, it is
an ultrasonic shield made of foam or the like whose acoustic impedance is different from that of
the lens 4a or which enhances the shielding effect. I hope there is.
[0021]
Also, although the acoustic lens 4 is illustrated as an open end for convenience of explanation,
the acoustic lens 4 is generally closed, and this is not excluded from the present invention. As
described above, the present invention can be variously modified. In short, an acoustic lens in
which the lens portion and the side plate made of the ultrasonic wave shielding member are
integrally molded separately, and an array type probe using the same. The child basically belongs
to the technical scope of the present invention.
[0022]
According to the present invention, the lens portion of the acoustic lens formed on the
piezoelectric element group is equal to or less than the length of the piezoelectric element, and
the leg portion extending from the outer periphery of the lens portion is the lens portion. As a
separate ultrasound shield, the lens portion and the leg portion are integrated. The method
further comprises the steps of: forming a leg between the concave first mold and the convex
second mold having a curvature; and forming a lens, the lens and the leg To produce an acoustic
lens, thereby providing an acoustic lens excellent in versatility, and eliminating an ultrasonic
wave leakage from the end of the acoustic lens to provide an arrayed probe excellent in
resolution. Can be provided.
[0023]
Brief description of the drawings
[0024]
1 is a diagram for explaining the first embodiment of the present invention, the same figure (a) is
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a side sectional view of the array type probe, the same figure (b) is a diagram of an acoustic lens.
[0025]
2 is a diagram for explaining the manufacturing method of the second embodiment of the
present invention, both FIGS. (A) (b) is a schematic view of the mold.
[0026]
3 is a side cross-sectional view of the array-type probe for explaining another example of the first
embodiment of the present invention.
[0027]
4 is a side cross-sectional view of the array-type probe illustrating yet another example of the
first embodiment of the present invention.
[0028]
5A and 5B are diagrams for explaining the conventional example, in which FIG. 5A is a front
sectional view of the arrayed probe, FIG. 5B is a side sectional view thereof, and FIG. 5C is a
diagram of an acoustic lens.
[0029]
6 is a side sectional view of the array-type probe for explaining the conventional example.
[0030]
7 is a cross-sectional view of a molding die of an acoustic lens for explaining the conventional
example.
[0031]
8 is a schematic side sectional view of an array-type probe for explaining the conventional
example.
[0032]
FIG. 9 is a side cross-sectional view of the array type probe for explaining the problems of the
conventional example.
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[0033]
Explanation of sign
[0034]
Reference Signs List 1 backing material 2 piezoelectric element 3 acoustic matching layer 4
acoustic lens 4 a lens portion 4 b leg portion 4 c side plate 5 mold layer 6 base 7 case 8 first
mold 9 second mold , 10 Mold, 11 space part.
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