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TECHNICAL FIELD The present invention relates to an ultrasonic transducer, and more
particularly to an ultrasonic transducer having an aspheric emitting surface. 2. Related Art
Conventionally, an ultrasonic transducer is used to generate an ultrasonic beam in an ultrasonic
microscope, an ultrasonic diagnostic apparatus, an ultrasonic flaw detector, and the like. FIG. 1
shows a typical ultrasonic transducer used in an ultrasonic microscope, and an acoustic lens ?
? consisting of an ultrasonic wave propagation medium which is sandwiched between ultrasonic
transducers 1t-electrodes 2 and 3 The other end 4a of the acoustic lens 4 is concaved to provide
a lens action to focus the ultrasonic beam. Such an ultrasonic transducer has internal reflection
at the acoustic lens 4 and has a disadvantage that the power of the ultrasonic beam emitted to
the outside is significantly reduced. That is, when the acoustic lens 4 is formed of sapphire, the
acoustic impedance of the liquid medium 6 interposed between the acoustic lens 4 and the
subject 5 and the acoustic impedance of sapphire are largely different from each other. The
emitted ultrasonic beam is largely reflected at the boundary between the acoustic lens 4 and the
liquid medium 6. Furthermore, sapphire, which is a material constituting conventional acoustic
lens numbers, is a very hard material, and its processing is very difficult. Therefore, the
conventional acoustic lens is a spherical lens, and has the disadvantage that the aberration is a
problem. In order to eliminate such defects, it has also been proposed to directly polish the
surface of a quartz plate or a piezoelectric ceramic ultrasonic transducer to form a concave
shape, but since mechanical polishing is performed, the ultrasonic transducer is used. The
thickness of 11 can not be reduced, and it has not been possible to generate ultrasonic waves in
the ultrahigh frequency band of several megahertz or more. In addition, it is difficult to form an
aspheric surface by such mechanical polishing. In order to solve the above-mentioned drawbacks,
in Japanese Patent Application Laid-Open No. 58-25889, a 1 iil 1 ball is pressed against an agent
4 such as a metal plate to form a concave dimple and ultrasonic waves are formed on the
concave surface. The ultrasonic transducer user who has attached the vibrator and the electrode
is shown, but in this case, the accuracy of the concave-shaped dent formed by the hard ball is due
to the elastic deformation and the inertia deformation of the metal plate. There is a drawback
that it is hard to come out. In particular, accurate formation of an aspheric surface is extremely
difficult in practice in such a method. OBJECTS OF THE INVENTION The object of the present
invention is to eliminate the above-mentioned drawbacks, to eliminate internal reflection at the
acoustic lens, and to emit the inertia V of the superhigh frequency band, and to be easily
aspheric. It is an attempt to provide an acoustic transducer.
The ultrasonic transducer according to the present invention is characterized in that the
ultrasonic transducer and the entire electrode are deposited on the surface of a damping member
made of a molded body. EXAMPLE FIG. 2 illustrates the sequential steps of producing the selfevident ultrasonic transducer. As shown in FIG. 2A, a mold 11 is prepared in which the bottom
IJa is a desired chip 1, for example, an aspheric surface. This mold 1 can be made of, for example,
a fluorocarbon resin. Next, a damping material is injected into the mold 11 from the nozzle J2
and molded. As this damping material, for example, an epoxy resin can be used as a metal
powder. The metal powder added to the epoxy resin is a powder of a metal having a large
specific gravity, such as tungsten or copper, which provides desired damping characteristics and
reduces shrinkage of the epoxy resin, and ensures dimensional accuracy of the aspheric surface.
become. Next, as shown in FIG. 2B, the damping member 13 molded in the mold 11 is taken out
of the mold and molded into an aspheric surface corresponding to the bottom surface 11a of the
mold 11 and the fc coated surface 810. Deposit uniformly by film 14t ? ? sputtering. Further,
as shown in FIG. 2G, a lower electrode 15 consisting of an upper surface layer 4 of the SiO ?
film 14 and Au JWr is vapor deposited. The electrodes 15 'are not formed uniformly but partially.
It can be selectively etched until it is uniformly deposited. Next, as shown in the second
embodiment, the ultrasonic transducer 16 of znO, which is a piezoelectric material, is sputtered,
and an upper electrode 7 composed of a Ni-Or layer and an Au layer is vapor deposited thereon.
The upper electrode is also partially formed. Thereafter, in the second process, the portion
indicated by the oblique line # i1 of the piezoelectric film 6 is etched away with dilute sulfuric
acid to expose the lower electrode J5 so that the external lead wire can be connected. Finally
810. The film 18 is sputtered to obtain an ultrasonic transducer according to the invention as
shown in FIG. 2E. The invention is not limited to the embodiments described above, but many
variants are possible. In the example described above, ZnO is formed by sputtering as an
ultrasonic transducer, but a PVDF resin film can also be used. In the case of a gauze, after the
entire surface of a dumping member made of a molded body is completely coated, 1 PVDT resin
film is put on it, and then the entire surface of the electrode is coated and then an insulating
resin is applied. Furthermore, in the above-described example, the ZnO pressure ?li? and the
film are used as the ultrasonic transducer, but it is of course possible to use other material sound.
Moreover, although it was set as the surface all aspherical surface of a damping member in the
example mentioned above, it can also be set as a spherical surface of course. According to the
present invention, since the ultrasonic transducer and the electrode are attached to the surface of
the damping member made of a molded body, there is no internal reflection as in the case of
using a conventional acoustic lens, so a large power ultrasonic beam can be It can be projected
on the subject. In addition, since the resonance of the ultrasonic imaging moving member can be
effectively suppressed by the damping member and the thickness of the ultrasonic transducer
can be easily made thin, it is possible to generate all ultrasonic waves in the ultra-high directional
V band. Can. Furthermore, it is possible to make an ultrasonic transducer having an aspheric
surface much more easily than polishing an acoustic lens or polishing an ultrasonic imaging
element. In addition, since it is not an acoustic lens but a damping member that is formed by
molding, the precision may be lower than that of a lens, and it can be easily molded by a resin,
and furthermore, a hard sphere is pushed against the base to make it concave. There is an
advantage that the accuracy is higher than when forming.
Brief description of the drawings
FIG. 1 is a cross-sectional view showing the structure of a conventional ultrasonic transducer
having an acoustic lens, and FIGS. 2A to 2E are cross-sectional views showing successive
manufacturing steps of an ultrasonic transducer according to the present invention.
l] иии Molded type lea и и Aspheric surface 1a и и Damping member 14 и и и SiO ? film 15 и и и lower
electrode 16 и и и и и и и и и и и и и upper electrode 18 и и и SiO ? Membrane. Patent issued by one
person OLYMPUS OPTICAL CO., LTD. Attorney Barber Sugimura Atsushi Hidemura Figure 1
Figure 2
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