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JPH0473692

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DESCRIPTION JPH0473692
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
method of manufacturing an acoustic lens for an ultrasonic probe used in a medical ultrasonic
endoscope or the like. [Conventional Art] Conventionally, a lens manufacturing method of this
kind is known from Japanese Patent Application Laid-Open Nos. 57-185792 and 1-223720, and
the like, and usually, casting, cutting grinding, etc. using a resin or the like. Or bonding a layer
such as resin to the piezoelectric element and cutting it into a lens shape, or placing the vibrator
in a casting mold and There is a method of casting and curing a liquid resin material to be a lens
after curing in the state, or a method of forming a piezoelectric element in a concave surface or
the like to have a lens effect. [Problems to be Solved by the Invention] The above-mentioned
conventional method has a disadvantage that it requires many equipment and complicated
processes because the lens is formed by molding, casting, cutting, grinding or the like.
Furthermore, when using molds and castings, it is necessary to use different molds in order to
form lenses of different focal lengths and apertures. The manufacture of an aspheric lens, a thin
lens for a high frequency ultrasonic probe, a lens for a small ultrasonic probe, etc. is extremely
difficult. Furthermore, when a bonding step is required, lens distortion during bonding, inclusion
of air bubbles in the bonding layer, variation or deterioration of performance due to nonuniformity of the bonding layer, peeling of the bonding layer after long use, etc. Reliability will be
reduced. When processing the lens shape by cutting etc. after joining, it is due to the stress
applied at the time of processing. Problems such as peeling of the bonding layer may occur. Due
to these factors, it is not possible to inexpensively manufacture a high-performance, highreliability ultrasonic probe. The present invention has been made in view of the above problems,
and an object of the present invention is to provide a method of accurately forming an acoustic
lens without using a bonding step. [Means for Solving the Problems] In the method of the present
invention, when forming an acoustic lens, an ultraviolet curable resin material is used as a
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material, and the resin is cured by irradiating the ultraviolet light on the piezoelectric vibrator to
piezoelectricize the lens shape. It is characterized in that it is formed directly on the vibrator. In
another example of the method of the present invention, in forming an acoustic lens, an
ultraviolet curable resin is used as the material, and the degree of curing of the resin on the
piezoelectric vibrator is the most advanced in the vibrator center and the step corner The lens
shape can be formed directly on the piezoelectric vibrator by selectively curing the resin by
ultraviolet irradiation so as to be weak continuously or continuously.
In still another example of the method of the present invention, in forming an acoustic lens, a
resin which is cured in a single resin layer using two or more kinds of ultraviolet curable resins
having different speeds of sound in the medium after curing as materials. By changing the type
of the lens, it is possible to form the lens shape directly on the piezoelectric vibrator by changing
the sound velocity distribution in the resin layer in a plane orthogonal to the radiation direction
of the sound wave. FIG. 1 (a) shows the basic concept of the acoustic lens manufacturing method
of the present invention. As apparent from the figure, according to the present invention, the
piezoelectric vibrator 2 is placed in the container 1 and the ultraviolet irradiation device 3 is
placed above the container l. Between the container 1 and the ultraviolet irradiation device 3, an
optical system 17, an aperture (not shown), a filter (not shown), etc. are provided to control the
ultraviolet light to be irradiated. [Operation] The liquid ultraviolet curing resin 5 is filled in the
container 1. The depth of the resin, that is, the liquid can be controlled, and the depth t of the
resin liquid in the ultraviolet light irradiated portion on the piezoelectric vibrator 2 is set to be
equal to the thickness of the acoustic lens in this portion. In this state, the ultraviolet irradiation
device 3 also irradiates the ultraviolet light 13, and the wave! I cure only the resin of the subsidy
part. The intensity, the irradiation interval, and the like of this ultraviolet light are controlled by
the above-described optical system 17, an aperture (not shown), a filter (not shown), and the like.
As a result, the lens 20 as shown in FIG. 1 (b) can be formed. Embodiment 1 A first embodiment
of a method of manufacturing an acoustic lens according to the present invention is shown in
FIGS. 2 (a) and 2 (b). In the figure, the same elements as those shown in FIG. 1 are given the same
reference numerals. The container l is held on the table 18, and the piezoelectric vibrator 2 is
installed on the bottom of the container l. An ultraviolet irradiation device 3 and an optical
system 17 are provided above the container 1. Ultraviolet light by this optical system I7! ! The
ultraviolet light 13 emitted from the IQ emitter 3 converges on the surface of the resin material.
The position of the UV irradiated portion 16 on the resin can be arbitrarily moved by controlling
the table 18 or the optical system 17. The container 1 is filled with the liquid ultraviolet curing
resin 5 therein so that the depth, that is, the amount of liquid can be controlled. First, liquid
ultraviolet curing resin 5 is placed in the container 1 and its depth is set so that the depth of the
liquid on the piezoelectric vibrator 2 is equal to the thickness of the thinnest portion of the
acoustic lens after curing. Do. In this state, the ultraviolet light 19 converged by the optical
system 17 is irradiated to cure only the resin of the irradiated portion of the ultraviolet light.
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UV light is scanned in this state, and the entire resin to be cured is irradiated with the currently
set thickness. Thereafter, while increasing the depth of the ultraviolet curable resin 5
sequentially, the resin is sequentially cured by ultraviolet light irradiation. In this case, the scan
of the ultraviolet light is performed while increasing the diameter concentrically, and at the same
time, the depth of the resin 5 is made deeper toward the outside. After this series of steps is
completed, as shown in FIG. 2 (b), a resinous acoustic lens 20 is formed on the piezoelectric
vibrator 2. The planar shape of the acoustic lens 20 is not limited to a circle, but may be an
ellipse, a square, or the like by changing the scan path of ultraviolet light. As described above,
according to this example, the acoustic lens can be formed directly on the piezoelectric vibrator.
This eliminates the need for a bonding step, which results in distortion of the lens at the time of
bonding, inclusion of air bubbles in the bonding layer, dispersion or deterioration of performance
due to non-uniformity of the bonding layer, and reliability due to peeling of the bonding layer
after long use. It is possible to prevent the decrease. Further, at the time of processing, since it is
sufficient to place the resin plate on the bottom of the flat container, workpiece handling
becomes extremely easy. For the same reason, the planar shape of the lens can be arbitrarily
selected as the shape outside the field. Furthermore, since processing can be strictly controlled
by ultraviolet light irradiation and the liquid depth of the liquid ultraviolet curing resin, changing
the size and shape of the lens also depends on the intensity of the light source, the optical
system, the irradiation time and the depth of the resin liquid. It is possible to flexibly cope with
the adjustment of the above, and an acoustic lens having an aspheric effect can be easily formed.
As described above, according to this example, the acoustic lens can be formed strictly and
flexibly by these effects. Second Embodiment Next, a second embodiment of the method of
manufacturing an acoustic lens according to the present invention will be described with
reference to FIGS. 3 (a) to 3 (e). In the figure, the same elements as those shown in FIG. 1 are
given the same reference numerals. Also in the present embodiment, the piezoelectric vibrator 2
is fixed to the bottom surface of the container l, and the ultraviolet irradiation device 3 is
provided above it. An aperture 4 is provided between the container 2 and the ultraviolet curing
device 3. Also in this example, the liquid ultraviolet curing resin 5 is filled in the container 1. At
this time, the depth t of the resin 5 is set such that the depth of the liquid on the piezoelectric
vibrator 2 is equal to the thickness of the thinnest portion of the acoustic lens after curing. In this
state, ultraviolet light 8 having a 5-ring cross section is irradiated to cure only the resin of the
irradiated portion. The ultraviolet light 8 of the ring-shaped cross section is formed by
transmitting the ultraviolet light 13 emitted from the ultraviolet irradiation device 3 to the
aperture 4.
In this case, as shown in FIG. 3 (c), the shape of the transmitting portion 9 of the aperture 4 is a
plurality of concentric rings, and inscribed or circumscribed in the transmitting portion 9 of the
adjacent aperture, Alternatively, as shown in FIG. 3 (d), the outer shape 10 does not change, and
only the inner shielding part 1) can be made smaller. The shape of the transmitting portion 9 and
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the shielding portion 1) is not limited to an annular shape (it may be an arbitrary shape such as
an elliptical shape, an oval shape, or another polygonal shape). The above steps are repeated by
changing the depth of the resin solution and the cross-sectional shape of the ring-shaped
ultraviolet light 8. At this time, the liquid depth of the resin is deep (in the direction of becoming,
and the cross-sectional shape of the transmitting part of the aperture is such that in the case of
the former, the next hardening part can be made outside the previous hardening part, and in the
latter case. Is set so that the diameter of the shielding portion 1) is increased stepwise. Therefore,
finally, the thickness of the cured resin layer is the same as the thickest portion of the lens layer.
When this process is repeated as described above, as shown in FIG. 3 (e), it is possible to form a
substantially concave lens having a stepped surface. The step d in the step portion in this case
corresponds to the amount of change in the depth of the resin liquid. If the step difference of the
stairs is kept smaller than 1?8 of the wavelength of the ultrasonic wave used, the lens effect will
not be impaired. As described above, according to the present embodiment, in addition to the
effects shown in the first embodiment, since the lens shape is determined by the aperture shape,
the reproducibility is excellent and it is suitable for mass production. In addition, by controlling
the amount of change in the liquid depth of the resin, the focal length of the formed lens can be
arbitrarily adjusted, and therefore, the processing flexibility is also enhanced. Furthermore,
changes in lens size can be accommodated by changing the number of apertures used. Third
Embodiment A third embodiment of the method of producing an acoustic lens according to the
present invention will be described with reference to FIGS. 4 (a) to 4 (C). In the figure, the same
components as those shown in FIG. 1 are denoted by the same reference numerals. Also in this
embodiment, the basic configuration of the apparatus for carrying out the acoustic lens
manufacturing method is the same as that described in the second embodiment, but the
difference is in the aperture as shown in FIG. 4 (a). Use filter 12 instead of 4. The light
transmission heavy distribution of the filter 12 is set so as to increase in transmittance toward
the outside as shown in FIG. 4 (b). The intensity distribution of the ultraviolet light irradiated to
the liquid ultraviolet curing resin 5 is also based on the transmittance distribution.
This distribution is effective whether it is a step-like distribution or a continuous distribution as
shown in FIG. 4 (b). Furthermore, in the present embodiment, ultraviolet light irradiation is
performed only once, and the depth of the liquid resin liquid is not changed either. The operation
of this embodiment is basically the same as that described for the second embodiment. That is,
the liquid ultraviolet curing resin 5 is filled in the container 1, and the depth t of the resin in this
case is such that the depth of the liquid of the piezoelectric vibrator 2 is equal to the thickness of
the acoustic lens after curing. Set to a value. A filter 12 is provided between the ultraviolet
irradiation device 3 and the resin 5 and the ultraviolet light 13 is irradiated. The intensity
distribution of the ultraviolet light 15 transmitted through the filter 12 is controlled by the filter
12 so that the peripheral portion is stronger than the central portion. Because of this, hardening
of the resin on the non-irradiated surface of the ultraviolet light proceeds more than in the
central portion. The sound velocity distribution in the resin layer is also made to conform to the
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distribution of the degree of hardening. As described above, since the sound velocity distribution
can be obtained, as shown in FIG. 4 (C), the phase of the sound wave oscillated differs between
the central portion and the peripheral portion, and the sound wave converges on the concave
surface, and the lens effect It comes to occur. According to this embodiment, in addition to the
effects described in the second embodiment, since the light intensity can be controlled with a
minimum of one filter, the process becomes easy, and hence the reproducibility becomes
extremely high. Further, the change in the size of the lens can be coped with by controlling the
convergence of the ultraviolet light incident on the filter. Furthermore, when changing a point
distance, it can respond by using several filters in piles. Fourth Embodiment A fourth
embodiment of the method of manufacturing an acoustic lens according to the present invention
will be described with reference to FIGS. 3 (c) and 3 (d). In the figure, the same components as
those shown in FIG. 1 are denoted by the same reference numerals. Also in this embodiment, the
basic configuration of the apparatus for carrying out the acoustic lens manufacturing method is
the same as that described in the second embodiment, and therefore the apertures shown in
FIGS. 3 (C) and (d) are used. use. The operation of this embodiment is basically the same as that
described in the second embodiment. That is, the liquid ultraviolet curing resin 5 is filled in the
container l, and in this case, the depth t of the resin to be controlled is equal to the thickness of
the acoustic lens after curing of the resin liquid on the piezoelectric vibrator 2 Set to be In this
embodiment, the ultraviolet irradiation time is configured to be gradually extended from the
central portion toward the peripheral portion. This is because the aperture shown in FIG. 3 (d) is
used in order of decreasing size from the largest one in the shielding part 1), or the diameter of
the transmitting part 9 of the aperture shown in FIG. 3 (C) is large. It can be realized by
irradiating the ultraviolet light whose intensity is as high as that of the critical one.
As a result, in the resin on the non-irradiated surface, as shown in FIG. 3 (e), peripheral curing
proceeds more than in the central portion, as described in the third embodiment. The sound
velocity distribution in the resin layer also conforms to the distribution of the degree of
hardening. Moreover, it is also possible to use together formation of the lens shape which was
mentioned above. As described above, according to the present embodiment, in addition to the
same effects as those described in the second embodiment, the irradiation intensity distribution
of light can be controlled by the aperture, so processing becomes easier and its reproducibility
becomes higher. . In addition, when the present embodiment is used in combination with the
formation of the lens shape, the control range of the lens effect can be further broadened. Fifth
Embodiment A fifth embodiment of a method of manufacturing an acoustic lens according to the
present invention will be described with reference to FIGS. 2 (a) and 2 (b). In the figure, the same
components as those shown in FIG. 1 are denoted by the same reference numerals. Also in this
embodiment, the basic configuration of the apparatus for carrying out the acoustic lens
manufacturing method is the same as that described in the first embodiment, and therefore, the
one shown in FIG. 2 (a) is used. The operation of this embodiment is basically the same as that
described for the first embodiment, and therefore FIG. 2 (a) is used for the description. That is,
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the liquid ultraviolet curing resin 5 is filled in the container 1, and in this case, the depth t of the
resin to be controlled is the thickness of the acoustic wave after curing of the depth of the resin
liquid on the piezoelectric vibrator 2 Set to be equal to In this embodiment, the ultraviolet
irradiation time is configured to be gradually longer as it goes from the center to the peripheral
part, or as the irradiation intensity becomes stronger as it proceeds from the central part to the
peripheral part. This can be realized by lengthening the irradiation time of the ultraviolet light
and irradiating the ultraviolet light with high intensity as the irradiated part of the resin is closer
to the peripheral part. As a result, as shown in the third section (e), curing of the resin on the
surface to be irradiated with ultraviolet light proceeds more than in the central portion, as
described in the third embodiment. The sound velocity distribution in the resin layer also
conforms to the distribution of the degree of hardening. It is also possible to use both the
formation of the lens shape and the change in the degree of curing of the resin. As described
above, according to the present embodiment, in addition to the effects described in the second
embodiment, basically, the adjustment of the depth of the liquid of the ultraviolet curing resin
may be performed at one time, so that the process can be extremely facilitated. it can. Further, as
described above, when the present embodiment is used in combination with the formation of the
lens shape, the control range of the lens effect can be further widened.
Sixth Embodiment A sixth embodiment of a method of manufacturing an acoustic lens according
to the present invention will be described with reference to FIG. 3 (c). In the figure, the same
components as those shown in FIG. 1 are denoted by the same reference numerals. Also in the
present embodiment, the basic configuration of the apparatus for carrying out the acoustic lens
manufacturing method is the same as that described in the first embodiment or the second
embodiment, and in the case of the same as the seventh embodiment. Use the same aperture as
described in FIG. 3 (c). In this embodiment, apart from the above-described place, an ultrasonic
cleaner (not shown) filled with an organic solvent, and plural kinds of liquid ultraviolet curing
resins (not shown) having different speeds of sound in the material after curing Prepare. As an
example of the resin material, it is conceivable to use a completely different kind of liquid UV
curable resin 5 or use of a liquid UV curable resin 5 in which powder such as ceramic powder is
distributed. In the latter case, a plurality of resins having different amounts of dispersed powder
are used. Also, they can be used simultaneously. The operation of this embodiment is basically
the same as that described in the first embodiment. That is, the liquid ultraviolet curing resin 5 is
filled in the container 1. At this time, the depth t of the resin to be controlled is such that the
depth of the liquid on the piezoelectric vibrator 2 is equal to the thickness of the acoustic lens
after curing. To set. In this state, ultraviolet light is irradiated to cure only the resin of the
irradiated portion. Thereafter, the uncured ultraviolet curable resin is removed by ultrasonic
cleaning to leave only the cured ultraviolet curable resin 6 on the ring. The above steps are
repeated by changing the type of resin and the location of the resin to be cured. At this time,
when different types of resins are used, they are used in order of increasing speed of sound after
curing. In addition, when using an ultraviolet curable resin in which powder is dispersed, the
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amount of powder in the resin is set to be smaller as it gets farther from the center during
curing. The diameter of the part to be cured is set so that the next cured part can be made
outside the previous cured part. If this process is repeated as described above, the sound velocity
distribution as shown in FIG. 5 can be obtained in the resin layer after curing. As described
above, since the distribution of the velocity of sound can be performed, the phases of the
oscillated sound waves differ between the central portion and the peripheral portion, and the
sound waves converge on the concave surface, and a lens effect is generated. Further, as
described above, it is also possible to concurrently use the formation of the lens shape and the
change of the degree of curing of the resin. As described above, according to this embodiment, in
addition to the above-described effects, it is possible to flexibly cope with changes in focal length.
[Effects of the Invention] As described above, according to the acoustic lens manufacturing
method of the present invention, the acoustic lens for the ultrasonic probe can be formed on the
piezoelectric vibrator with high performance and high reliability, omitting the bonding step. It
can be formed directly.
[0002]
Brief description of the drawings
[0003]
FIG. 1 (a) is an explanatory view showing the basic concept of an apparatus for carrying out the
acoustic lens manufacturing method of the present invention, and FIG. 1 (b) is a sectional view
showing the configuration of the acoustic lens formed by the method of the present invention.
FIG. 2 (a) is a perspective view showing a first embodiment of an apparatus for carrying out the
acoustic lens manufacturing method of the present invention, and FIG. 2 (b) is a sectional view
showing the configuration of the acoustic lens formed according to the first embodiment. is
there. FIG. 3 (a) is a cross-sectional view showing a second embodiment of an apparatus for
carrying out the method of manufacturing an acoustic lens according to the present invention,
FIG. 3 (b) is a cross-sectional view for explaining the operation thereof, and FIG. ) And (d) are
exploded perspective views illustrating the configuration of the aperture used in the second
embodiment. FIG. 3 (e) is a cross-sectional view showing the structure of an acoustic lens formed
by the method of the present invention. FIG. 4 (a) is a cross-sectional view showing a third
embodiment of the apparatus for carrying out the acoustic lens manufacturing method of the
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present invention, FIG. 4 (b) is a cross-sectional view for explaining the light transmission
distribution of the filter, FIG. 9 is an explanatory view showing the sound velocity distribution of
the acoustic lens formed according to the third embodiment. FIG. 5 is an explanatory view
showing a sound velocity distribution of an acoustic lens formed by the method of manufacturing
an acoustic lens according to the present invention. l и и и Container 2 и и и Piezoelectric vibrator 3 и
и и Ultraviolet light! In injection device 4 иии Aperture 5 и и UV curable resin (liquid) 6 и и и UV curable
resin (after curing) 1 и и и и и и и и и и и и и и и и и Light aperture light transmitting part Aperture light
shielding part (peripheral part) Aperture light shielding part (central part) filter ultraviolet light
ultraviolet light (after filter transmission) irradiated part optical system table ultraviolet light
(convergent light) acoustic lens container piezoelectric vibrator ultraviolet? UV curing resin
(liquid) UV light system acoustic lens Fig. 2 (a) (b) Fig. (A,) (b) Fig. 3 (a) (b) Fig. 3 (e) Fig. 4 (a)
Figure 4 (b) (c)
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