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Technical Field to which the Invention belongs The present invention 1 has a frequency of
several MH! The present invention relates to a method of manufacturing a concave transducer
used for focusing a high frequency band ultrasonic wave of several tens Mllz or less.
[Conventional technology and its problems] Conventionally, a single point in the liquid (-focuss
on ultrasonic waves to generate a strong ultrasonic wave field, or a concave vibrator to improve
the resolution of the ultrasonic diagnostic apparatus) It has been used for focusing transducers.
However, with conventional concave vibrators, both surfaces of inorganic single crystals such as
quartz plates and piezoelectric ceramics such as PZT are polished (thereby making concave
curved plates, so the thickness of curved plates can not be made too thin and can be generated)
Ultrasonic waves also have the disadvantage of being only several MHz. Furthermore, the thinner
the thickness of the curved plate, the smaller the yield of productivity is. On the other hand, it is
also well known to form a piezoelectric film transducer by a conventional film forming technique
4 such as concave side or convex side 1 varnish battering method on a curved substrate as a
conventional concave vibrator. C Tokusho 53-2! M489) Because of the extremely slow sputtering
speed of piezoelectric ceramics made of PZT or ZnO, the thickness of the piezoelectric film can
not be very large, and the ultrasonic waves that can be generated have the disadvantage of being
limited to several hundred MHz or more. The Furthermore, as a probe for an ultrasonic
diagnostic apparatus, it also has a defect that the acoustic impedance with the living body is bad.
On the other hand, a polymer piezoelectric material represented by BvF, in which the W echo
impedance is close to that of water or a living body and ultrasonic wave propagation loss is small
and mechanical Q is small, so short pulses are obtained and distance resolution is improved. In
addition to the fact that the thickness of the piezoelectric film can not be increased too much and
the crystal structure can not be arbitrarily controlled by sputtering, it is not possible to control
the crystal structure arbitrarily, so transmission or reception for ultrasonic diagnosis as a
generation source of ultrasonic wave field. Satisfactory elements have not been obtained. For this
purpose, an adhesive is used to bond a uniaxially stretched or biaxially stretched polymer
piezoelectric material film such as 174 wavelength thick PvF or the like on a concave 1/4
wavelength thick acoustic wave absorbing plate forming a part of a spherical shell. It is also
known. However, when bonding with an adhesive, an adhesive that requires stretching
temperature or higher (= an adhesive that requires a curing temperature can not be used because
it causes deterioration of the piezoelectric function due to relaxation of β crystal, and reliability
such as heat resistance and moisture resistance It depends on that of the adhesive rather than
that of the piezoelectric material. Furthermore, since a solder having an unnecessary capacitance
is inserted between the piezoelectric material and the forelimb absorbing plate, a drop in output
sensitivity can not be prevented.
Furthermore, it is also conceivable to use a bonding agent: a polymer piezoelectric film with a
thickness of 1/4 21/4 wavelength (a heat absorbing plate of a 174 wavelength thickness and a
heat absorbing plate may be considered, but as in the above case, In this case, the temperature
rises to around the softening point of the polymeric piezoelectric material, particularly in this
case, so that the transition of the β-type crystal to the α-type crystal can not be avoided, and
the piezoelectric function is greatly reduced. SUMMARY OF THE INVENTION The present
invention has been made to eliminate these disadvantages, and integrates a polymer piezoelectric
film containing .beta.-type crystals on the surface of a support forming a part of a spherical shell
in advance, plating, vacuum evaporation, After providing the sound wave absorbing material of
174 wavelength thickness by the ordinary film forming technology such as sputtering, the
polymer piezoelectric film of the shape forming a part of the spherical shell with the sound
absorbing material adhered is detached from the support surface forming a part of the spherical
shell The present invention relates to a method of manufacturing a polymeric piezoelectric
concave transducer formed by SUMMARY OF THE INVENTION A detailed description of the
invention will now be given using the drawings. 1st I! i! 1l (a-d) integrates the polymeric
piezoelectric film on the support surface which forms a part of the spherical shell, and gives the
same structure as the support surface shape to the bacterial molecular piezoelectric film, and FIG.
6 shows a cross-sectional view of an embodiment in which an acoustic wave absorption layer of
174 wavelength thickness is provided and then peeling is performed between the support and
the polymeric piezoelectric film. In these embodiments the shell is a circularly cut curved plate so
that the structure is symmetrical about the centerline. In FIG. 1al, a curved plate (1) to be a
support is previously X! In the case where the polymer piezoelectric film (2) of 1⁄4 wavelength
thickness provided with +31 is integrated, FIG. 1 is an ordinary film formation such as plating on
the polymer piezoelectric film (2) integrated. The acoustic wave absorbing material (4) made of
an inorganic substance with a thickness of 1⁄4 wavelength is provided by plating according to
the technology, FIG. 1 FIG. 1cl is a support or a curved plate 1 forming a part of spherical shell
from polymeric piezoelectric film In FIG. 1 dl shows a state in which the molded product is
pressed and formed by the punching process. In this case, it becomes a concave side radial wave
radiation surface. [Embodiment of the Invention] Next, a practical embodiment will be described.
The pigeon wave number of the ultrasonic wave to be operated is 5. The material 5 is a polymer
piezoelectric film, uniaxially stretched PvF and a film, the electrode 6 is a gold of good
conductivity, and a copper as a 1⁄4 wave thickness acoustic material. The case where the
distance is 75 degrees is described. In the same manner as in FIG. 1al, first, the radius of
curvature (r) of the support surface which is a part of the spherical shell is set to 150 in
accordance with the double of the focal length f, ie, the relationship of r-2f.
130 μm thick pre-polished PvF, film (6) with cold-sputtered gold metal (5) with both surface
thicknesses 800 or more integrated on the convex support surface forming a part of spherical
shell or Close contact. After the copper plate (7) of 1⁄4 wave thickness of the sound absorbing
material is provided by plating, it is separated from the surface of the support to make a 35 μm
diameter circular punch; stamped 1 and 6 as shown in FIG. Grounding from the radiation surface
side of the gold metal & (5) (a metal body connected from two (1B is taken from the copper plate
of sound absorbing material (7) and connected respectively via lead wire a and terminal (9) An
experiment of focused ultrasound was performed. On the contrary, when water was used as a
field medium and experiments were conducted with small spheres placed near the focal point C:
target a field, it was confirmed that the electroacoustic transducing operation was correctly
performed as a concave transducer. In addition, (+21, a31 is an insulator. [Effects of the
Invention] FIG. 3 shows an example of experimental results, in which the target a barrel is ca
figure in the vicinity of the focal point of the concave transducer αη prepared as described
above は X direction (−1 Cb figure) X The reflection intensities QB and (C) of the respective
ultrasonic waves are plotted against the respective movement distances {circle over (1)} and
{circle over (3)} while moving in the directions. The reflection intensity shows a sharp change
depending on the position of the target in the vicinity of the point @ of the focal length 75 諺 or
the point a 鴨 of X = O, and the concave transducer according to the present invention has
excellent beam focusing characteristics. I understand that there is. As described above, according
to the present invention, a high-reliability high-frequency polymer piezoelectric concave surface
obtained by transferring the convex surface of another support to the concave surface of the
radius of curvature determined by a predetermined focal length and sequentially plating and
casting. By forming by the method of manufacturing a transducer C2, it is possible to obtain
excellent characteristics.
Brief description of the drawings
The figures all illustrate the method of the present invention, and FIG. 1 (a) wcd) is a crosssectional view of a transducer for explaining the manufacturing procedure, and FIGS. 2 and 3
show an apparatus for explaining the evaluation measurement and FIG. 2 is a cross-sectional
view of a transducer.
(11 Curved plate (2X61 polymer film (3) (5) Den @ (4 X 7) Rear sound absorber representative
Patent Attorney Law Attorney Kin Kin (1 other) Figure 1 (Q) (C) (b) (d) -] Fig. 2
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