JPH01127947

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DESCRIPTION JPH01127947
[0001]
FIELD OF THE INVENTION The present invention relates to a method of manufacturing an
ultrasonic probe which electrically drives a piezoelectric vibrator to emit an ultrasonic wave into
a medium and to receive a reflection echo reflected from the medium. . 2. Related Art
Conventionally, an ultrasound probe of this type is configured as shown in FIG. In order to
efficiently radiate ultrasonic waves to the propagation medium, the ultrasonic element 1 is
provided with a back load material 3 that absorbs unnecessary ultrasonic waves on the back side
of the piezoelectric vibrator 4. Further, a first acoustic matching layer 5 and a second acoustic
matching layer 6 are provided on the front surface of the piezoelectric vibrator 4. Further, on the
front surface of the second acoustic matching layer 6, an acoustic lens 2 molded of a
thermoplastic resin is provided to focus ultrasonic waves. The acoustic lens 2 is provided with a
spherical recess 8 having a predetermined radius of curvature for maintaining an arbitrary
focusing distance, and a rib 10 is provided on the opposite side. 7 is a lead wire. In order to
assemble the ultrasonic element having the above configuration, an adhesive is applied to one
surface of the backing material 3 and both surfaces of the piezoelectric vibrator 4 and both
surfaces of the first matching layer 5 and the second matching layer 6 and the acoustic An
adhesive is applied to one plane of the lens 2. Then, the back load material 3 coated with the
adhesive, the piezoelectric vibrator 4, the first acoustic matching layer 5, and the second acoustic
adjustment layer 6 are bonded to each other to be integrated. Next, the united body is inserted
into a recess surrounded by one rib 10 of the acoustic lens 2, and the adhesive is fixed by heat
curing. Problems to be solved by the invention However, when fixed in this way, there are some
drawbacks. That is, since the acoustic lens 2 is formed by molding a thermoplastic resin, the
spherical concave portion 8 has a value slightly different from the desired curvature radius, and
if this is corrected at the time of assembly, the piezoelectric vibrator is broken There was a
problem. Further, since the thickness of the acoustic lens 2 differs depending on the curvature of
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the spherical recess 8, the bottom surface of the recess surrounded by the rib portion 10 of the
acoustic lens 2 is bent in a convex shape, whereby the acoustic lens 2, the second acoustic
matching layer 6, The thickness of the adhesive between each of the first acoustic matching layer
5, the piezoelectric vibrator 4 and the backing material 3 becomes nonuniform, which causes a
defect such as poor sensitivity or variation of the ultrasonic element. The present invention
solves the above-mentioned conventional defects, and prevents damage or the like of the
piezoelectric vibrator at the time of assembly, makes the thickness of the adhesive uniform, and
prevents the deterioration and variation of the sensitivity characteristic of the ultrasonic element.
The purpose is to Means for Solving the Problems The present invention achieves the above
object, and the technical means comprises a backing material, a piezoelectric vibrator having
electrodes on both sides, at least one acoustic matching layer, and a thermoplastic resin. An
adhesive is interposed between an acoustic lens having a spherical portion on the object side
surface, and a block made of an elastic body having a curvature surface substantially equal to
that of the acoustic lens is brought into contact with the spherical portion of the acoustic lens,
and pressure heating is performed. Therefore, the present invention is in a manufacturing
method for fixing and integrating each component.
Since the present invention fixes each component by heating the acoustic lens while pressing the
acoustic lens against the block, even if the acoustic lens is slightly distorted at the time of
molding, the block is made of the elastic body. Therefore, all deformation and distortion of the
acoustic lens can be absorbed, and breakage of the piezoelectric vibrator can be prevented at the
time of assembly of the ultrasonic element. In addition, uniform stress is applied to each
component by the action of the elastic body block, so that the thickness of the adhesive can be
made uniform, and sensitivity failure of the ultrasonic element and variation in sensitivity can be
prevented. In addition, an acoustic focusing lens made of a thermoplastic resin can be easily
shaped by heating and pressurizing up to the softening point of the resin. Furthermore, there is
also an effect of removing internal residual stress generated at the time of resin molding by
heating. Embodiments Hereinafter, embodiments of the present invention will be described in
detail with reference to the drawings. FIG. 1 is a partial cross-sectional view of a fixing jig for
embodying a method of manufacturing an ultrasonic probe in an embodiment of the present
invention. In the figure, 2 is an acoustic lens having a spherical radius on the surface, 3 is a back
load material, 4 is a piezoelectric vibrator, 5 is a first acoustic matching layer, 6 is a second
acoustic matching layer, and 7 is a lead wire. Configure the element. This configuration is
essentially the same as that shown in FIG. Reference numeral 9 denotes a cylinder guide which is
cylindrical and has a counterbore at the center of one surface. An elastic block 14 described later
is inserted into the counterbore. An elastic block 14 is formed of a cylinder having a desired
spherical radius precisely formed on one side and a flat surface on the other side. The elastic
block 14 is precisely fitted to the counterbore of the cylinder guide 9 via the spacer 15. The
spacer 15 is for preventing deformation and breakage of the elastic block 14, and is formed of a
rigid body. The reference numeral 12 denotes a cylinder, one has a counterbore that fits with the
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cylinder guide 9 with high accuracy, and the other has a through hole. Reference numeral 13
denotes a pressure shaft, one of which is a cylinder having a step, and a relief groove of the lead
wire 7 is provided in the side longitudinal direction. The pressure shaft 13 fits in the through
hole provided in one of the cylinders 12 with high accuracy. Next, the operation in the
configuration of this embodiment will be described. First, the ultrasonic elements are temporarily
assembled as a preliminary work. That is, the adhesive is applied to the bottom of the recess
surrounded by the rib portion 10 of the acoustic lens 2. Next, an adhesive is applied to both
surfaces of the second acoustic matching layer 6, and the adhesive is applied to the bottom of the
concave portion of the acoustic lens 2 to which the adhesive is applied.
Further, an adhesive is applied to both surfaces of the first acoustic matching layer 5 and
superimposed on the second acoustic matching layer 6. Similarly, the piezoelectric vibrator 4 is
superimposed via an adhesive. Further, an adhesive is applied to one surface of the backing
material 3 provided with the relief portion of the lead wire 7 and superposed on the piezoelectric
vibrator 4. The temporary assembly of the ultrasonic element is completed with the above
contents. Of course, the order of assembly of the ultrasonic elements is not limited to this. Next, it
inserts in the fixing jig shown in FIG. 1, and adheres, but the procedure is as follows. The
ultrasonic element, which has been temporarily assembled by applying an adhesive, is fitted and
inserted in the rib portion 10 of the acoustic lens 2 in a through hole provided in one of the
cylinders 12. At this time, the fitting of the rib portion 1o of the acoustic lens 2 and the through
hole of the cylinder 12 may be either too loose or too loose. Thus, with the ultrasonic element
fitted and inserted into the through hole of the cylinder 12, the cylindrical portion of the cylinder
guide 9 is gradually inserted into one counterbore of the cylinder 12. By advancing the insertion
state of the cylinder 12 and the cylinder guide 9, the spherical recess of the acoustic lens 2 and
the surface of the elastic block 14 come in contact with each other. In this state, the pressure
shaft 13 is inserted into the through hole provided in one of the cylinders 2 and heated while
applying pressure to the ultrasonic element via the back load material 3 with a constant weight.
As a result, the adhesive that fits between the acoustic lens 2, the second acoustic matching layer
6, the first acoustic matching layer 5, the piezoelectric vibrator 4, and the back load member 3 is
the second inside of the rib jO of the acoustic lens 2 and the second By pulling out into the space
15 through the side surfaces of the acoustic matching layer 6, the first acoustic matching layer,
the piezoelectric vibrator 4 and the backing material 3, a uniform adhesive layer is formed, and
in this state, it is cured and fixed. Further, since the spherical concave portion of the acoustic lens
2 is heated while being uniformly stressed from the entire surface by the elastic plate 14, there is
no problem such as partial deformation or distortion of the entire shape. Further, the
piezoelectric vibrator 4 and the like are not damaged by the buffer action of the elastic block 14.
Therefore, the focal length of the acoustic lens can be always kept constant exactly, and breakage
of the piezoelectric vibrator, sensitivity failure of the ultrasonic element, and variation can also be
prevented. Furthermore, the heating temperature is changed by using a thermosetting adhesive,
the first step is an acoustic lens distortion correction and annealing for removing internal
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residual stress, the second step is shaping the spherical lens shape of the acoustic lens, In the
third step, the temperature program is changed in one operation, such as curing and fixing the
adhesive, so that it is possible to manufacture an ultrasonic element having optimum
characteristics.
In the above embodiment, the elastic substance may be a substance having elasticity such as
silicone rubber, urethane rubber, neobrene rubber and the like. In particular, there is no concern
that the elastic body adheres to the silicone rubber even if the adhesive adheres incorrectly. In
the above embodiment, although the case where the object side surface of the acoustic lens is
provided with the spherical concave portion is described, it may be a spherical convex portion,
and in this case, the surface shape of the block also becomes a shape corresponding thereto Of
course. The effect of the present invention In summary, the present invention provides an
acoustic lens having an elastic block having a curvature surface substantially equal to that of the
acoustic lens when bonding each component of the ultrasonic element including the acoustic lens
having a spherical portion on the object side surface. The contact of the spherical part of the
surface with the pressure, heating is possible, and a uniform adhesive layer can be obtained in
the process of forming the element part of the ultrasonic probe, and the use of an elastic body
makes the stress more uniform with respect to the bonding site. It is possible to ensure a fixed
state with dispersion, and, conventionally, when each part has small protrusions, stress is
concentrated on the protrusions and the piezoelectric vibrator is not broken or uniform pressure
can not be measured, so that the thickness of the adhesive layer By using the elastic body, the
elastic body absorbs the small convex portion, and the above problem is solved, the work is
further improved, and the occurrence of defects in the process is drastically reduced. Feel of the
ultrasonic element Poor, has the advantage of being able to prevent the variation in sensitivity.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a partially broken sectional view of a fixing jig for embodying a method of
manufacturing an ultrasonic probe in one embodiment of the present invention, and FIG. 2 is a
sectional view showing a conventional ultrasonic element.
2 ... acoustic lens, 3 ... back load material, 4 ... piezoelectric vibrator, 5 ... first acoustic matching
layer, 6 ... second acoustic matching layer, 14 ... 5 J body block. Name of agent Attorney Nakao
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Toshio 1 person Figure 1
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