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JPS57112198

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DESCRIPTION JPS57112198
The specification 1, 1% of the invention claim 1, a plurality of ultrasonic transducers, which
transmit ultrasonic waves or receive external ultrasonic waves and convert them into electric
waves, are arranged in a spatial arrangement. In the ultrasonic probe configured as described
above, each of the above-mentioned ultrasonic transducers is approximately cylindrical or
spherical, and a plurality of ultrasonic transducers are used for the main part of the electroacoustic interconversion unit. An ultrasonic probe characterized in that it is configured to be
arranged at unequal intervals in a parallel direction to a sound wave transmission / reception
surface. (2) Control the transmission phase of the ultrasonic probe to electronically control the
traveling direction and focusing position of the synthesized wave front of the transmitted
ultrasonic wave, control the phase of the received signal and synthesize it In an ultrasonic
measurement apparatus for selectively receiving an ultrasonic wave from a specific incident
direction or a specific depth point, each of a plurality of ultrasonic transducers in the ultrasonic
probe is approximately cylindrical or spherical. An ultrasonic probe comprising a plurality of
ultrasonic transducers arranged at unequal intervals parallel to the ultrasonic transmitting /
receiving surface of main parts of an electro-acoustic interconversion unit, and the ultrasonic
probe An ultrasonic measurement apparatus, comprising: control means connected to a child and
controlled in a nine-time phase in consideration of an unequally spaced arrangement of the
plurality of ultrasonic transducers.
Ultrasonic probe and ultrasonic measurement apparatus
Detailed Description of the Invention The present invention relates to an ultrasonic probe and an
ultrasonic measurement apparatus D, an ultrasonic probe having a shape with less jIK% □
grating lobes, and an ultrasonic probe using the ultrasonic probe. The present invention relates
to ultrasonic measurement that can obtain an acoustic measurement device report.
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Conventionally, in an ultrasonic measurement apparatus such as an electronic scanning type
ultrasonic diagnostic apparatus, a large number of ultrasonic transducers arranged in a row on a
plane are selectively driven to scan an ultrasonic beam inside a specimen . Each of the ultrasonic
transducers has an elongated shape with a rectangular cross section (for example, 2.5 MI made
of PZT! When transmitting or receiving ultrasonic waves of g, width @, 4 m, length 13 ■,
thickness a, about 6 ■), parallel to the long axis equidistantly (for example, a 5 square) + 32
pieces PageEndPage: 1 However, as shown by AIKI, each ultrasonic transducer has electrodes 1b
and 1a above and below the electrostrictive transducer (for example, pzT) 1a of width W as
shown by AIKI. Although the radiation surface width W is 0.4 m and has a rectangular crosssectional shape with a thickness of about 0.6 points, the angular dependence of the radiation
energy is poor, and the radiation surface is perpendicular to the radiation surface. In the angle
range of about ± 20 ′ from the normal direction (referred to as angle e-oo), as shown in FIG. 1
((re)), it has an effective strength as compared with the case of θ-06, The angular dependence of
the intensity 0-00 at ± 45 'should be as close to the point as possible with the radiation surface
width W minimized. More, can be improved to be uniform, making the infinitely small W is not
possible with the restriction on the processing technique. Also, if W is reduced, the radiation
energy per one piece will be reduced, and it will be necessary to arrange them in large numbers,
but this will increase the number of phase control circuits, thereby increasing the number of
circuit components and increasing the cost. It has the drawback of becoming Moreover, since
each said ultrasonic transducer becomes small. The individual radiation energy is low, and in
order to obtain the required energy, it is necessary to arrange a large number of pieces at equal
intervals to collect and accumulate the transmission ultrasonic waves of the individual ultrasonic
transducers. However, when the ultrasonic transducers are arrayed at equal intervals in this way,
in addition to the ultrasonic beam in one traveling direction (main deflection angle θ0) formed
by the front wavefront of each of the ultrasonic waves transmitted by them, 1 Sub beams are
generated and traveled in other directions (this is called a so-called grating lobe) 0 For example,
as shown in the second flA, ultrasonic transducers arranged at equal intervals in 1-1-1 Ii + 1 It is
assumed that the front wave front of the ultrasonic wave transmitted by being phase-controlled
and driven is traveling toward the 0 mouth direction as shown by / as 10 'in FIG.
Also, as can be seen from FIG. 2, for example, the surface of the foremost II # of the ultrasonic
wave from the position of i + 1 is behind the front wave front of the ultrasonic wave from the
position of 1 by a wavelength λ. The second wave front is the wave front 2nd wave front of the
ultrasonic wave front from the position of i 1, and the third wave front etc. which is behind i form
the wave front 71all of θ1 direction Wavefronts of / 2 * f: and fs * fB 'and many other directions
are formed. Since sub-beams in directions other than the 0o direction are generated due to the
uniform pitch arrangement, 0 called grating lobes This grating lobe shortens the pitch interval
between individual ultrasonic transducers and integrates one transducer The shape of is also
minute, by increasing the total number of oscillators 01. θ2. The strength can be reduced by
setting θS or the like to a position separated by more than 00 and setting the angle-dependent
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deterioration angle of each transducer. However, on the other hand, on the assumption that the
angle dependency is bad, one problem is that the circuit increases with the increase of the
number of oscillations to be controlled, and the cost increases. An object of the present invention
is to arrange ultrasonic transducers in a predetermined shape and to arrange them at irregular
intervals and at intervals, and to provide an ultrasonic probe having a small total number of
transducers and good angular dependence. To provide a high-performance, low-cost ultrasonic
measurement device using it. According to the present invention, each of the ultrasonic
transducers is approximately cylindrical or spherical, and a plurality of ultrasonic transducers are
not parallel to the ultrasonic transmission / reception surface of the main part of the electricsound-speech mutual conversion portion. By arranging nine ultrasonic probes at equal intervals),
the above-mentioned conventional defects are eliminated, and this ultrasonic probe and its
unequal array of ultrasonic transducers are required. It has a control means which takes into
consideration and controls in the 9 o'clock phase. Hereinafter, FIG. 3 will be described in detail
with reference to the drawings in the embodiment of the present invention. FIG. 3 is a crosssectional view of one embodiment of the electro-acoustic interconversion unit of the ultrasonic
probe according to the present invention. FIG. In both figures, S and 51 to Is 4 are drive
electrodes, respectively, and are formed of metal wires such as copper and stainless steel. The
drive electrodes 5.51 to 56 are each circular in cross section. Reference numeral 6 denotes a
substantially rectangular substrate, which is usually made of plastic or the like as one material,
and can be mixed with tungsten powder or the like for attenuation of ultrasonic waves as needed.
The drive electrode 6 is fixed to an adhesive or the like on the substrate 6 as shown in FIG. 7 is
an EndPage: 2 flexible piezoelectric film such as polyvinylidene fluoride (PVDF), which is Ushaped in cross section and provided so as to cover a part of the drive electrode 5 and the
substrate 6.
A thin layer of chromium, nickel, aluminum, gold or the like or a composite layer thereof is
formed on the upper surface of the piezoelectric film 7 by vacuum evaporation or by coating a
thin layer of an organic conductive material to form the ground electrode 8 doing. The driving
chamber pressure is applied between the electrodes 5 and 8. Also, a signal is induced between
the electrodes 5 and 80. The piezoelectric film 7 coated with the ground electrode 8 is similarly
adhered and fixed to the drive electrode 6 and the substrate 6 fixed with an adhesive using a jig
or the like. Thus, one ultrasonic transducer is formed. 0 If the ultrasonic transducer has a
cylindrical shape in cross section in this way, the ultrasonic waves emitted from it are as shown
in FIG. 1 (Bl 1 can be made uniform in angular dependence (it is possible to widen the directivity)
without making the shape minute, FIG. 1 (in Bl, 4 is one 6 ultrasonic transducer, Electrodes 4b on
the upper and lower surfaces of the piezoelectric body made of PvD'F or the like. 4C is formed. In
addition, since the shape of the ultrasonic transducer does not have to be minute, individual
ultrasonic radiation energy can be made large. Therefore, the number of all transducers in the
array is greatly increased from 32 to 16 as in the prior art. The number of drive circuits can be
reduced as well. きる。 Furthermore, although a plurality of the above-mentioned ultrasonic
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transducers are arranged in a direction parallel to the ultrasonic transmitting / receiving surface,
the distance between adjacent ultrasonic transducers is a spacer of unequal thickness as shown
in FIG. Are placed at irregular intervals. The spacers 91 to 94 can be shared as the lead-out lines
of the ground electrode 8 by stacking them using conductive plastic, metal or the like as the
spacers 91 to 94 and using a conductive adhesive for assembly adhesion. In addition, since the
piezoelectric film 7 has a soft surface elasticity, adjusting the width of part of the substrate 6 and
the width when the piezoelectric film 5 is adhered to the upper part, the spacers 91 to 9a (91 to
91 in FIG. 4) 95) can also be designed to compress the piezoelectric film 7 at its contact as shown
in FIG. 3 and a better electrical contact than K can be obtained. FIG. 4 shows the appearance of a
configuration in which individual ultrasonic transducers are arranged and assembled in this
manner. Although FIG. 4 shows an example in which six ultrasonic transducers are used, it goes
without saying that any number of the transducers can be made. Connect the spacers 91 to 9s
(or 91 to 94 in the third section) shown in FIG. 4 to form a single ground electrode, and cover the
end with an insulating plastic adhesive etc. ° A tone change interconversion unit is created.
Here, according to the present embodiment, since the ultrasonic transducers are arranged at
unequal intervals by the spacers 91 to 91, the angle at which the wavefronts of two arbitrary
ultrasonic transducers are synthesized is Since the angles at which the wavefronts of 5.2 or more
ultrasonic transducers overlap at the same time are not different from the front wavefront
advancing direction shown by 00 in FIG. 2, the intensity of the grating lobe is In the present
embodiment, the ultrasonic wave is emitted above the ground electrode 8 in FIGS. 3 and 4 and
the ultrasonic wave from the outside is received on the upper surface of the ground electrode 8
in this embodiment. The ultrasonic probe used in the ultrasonic diagnostic apparatus has an
acoustic impedance matching layer on the upper surface of the ground electrode 8 and a
protective layer for preventing damage to the ground electrode 8 due to friction, etc. Both layers
can be shared by the same material, or they can be composite layers. Thus, according to the
ultrasonic probe of the present embodiment, the surface in the direction perpendicular to the
long axis direction of the cross section cylinder of the drive electrode 5 is fanned in the upper
side in FIGS. 3 and 4. During sector scanning, it has the angular dependence of uniform intensity,
and has the property of attenuating the grating rope to a substantially negligible extent. Next,
another embodiment in which ultrasonic transducers are two-dimensionally arrayed to transmit
ultrasonic beams in an arbitrary spatial direction will be described. FIG. 5 is a cross-sectional
view of one ultrasonic transducer in another embodiment of the ultrasonic probe according to
the present invention, and FIG. 6 is another embodiment of the ultrasonic probe according to the
present invention An appearance perspective view is shown. In FIG. 5,% 10 is a spherical
conductor electrode, which can be made of a metal ball such as a ball bearing. The spherical
EndPage: 3 electrode 10 is seated on the electrode 12 coated on the inner surface of the funnelshaped hole drilled on the multilayer printed circuit board 1tK to be conductive! It is electrically
connected and fixed by the adhesive. The funnel-shaped holes are through holes, and the
electrodes 12 are formed by the through hole technique of the multilayer printed circuit board
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11. This electrode tza through hole and printed wiring on the appropriate surface layer are
connected to the external drive electrode (shown as 13 in FIG. 6) such as PvDF on the
spherical electrode 10 and multilayer printed circuit board il The flexible piezoelectric material
14 is covered and adhered while being sandwiched by a jig or the like. A ground electrode 15 is
formed on the upper surface of the flexible piezoelectric material 14 in the same manner as in
the above embodiment. In this way, one ultrasonic transducer is formed, but this ultrasonic
transducer has three lines (for example, as shown by 1611 to 16S4 in FIG. 6) in the parallel
direction of its ultrasonic transmission / reception surface. They are arranged in a matrix of 1'rows (shown by X1 to Xs) +1 shown in Y1 to Ys), and a total of 12 are used, and each row of x1
to x4 is unequally spaced. Seri, Y1. Each line of ys is also unequally spaced.
Thereby, the electro-acoustic interconversion part of the ultrasound probe of a present Example
is comprised. Here, the ultrasonic transducers i 611 s 1 @ 21 1 631 of 11 columns (1 to 4) are
connected as a group to be the driving side, and the ultrasonic transducers 16 j 1 of the ground
spread Yj row (jtil 3). If 1j 52, 16 j 3 and 16 j 4 are connected as a group and the electrodes are
divided so as to be isolated from each other, driving any electrode of Xi and Y j can be configured
to drive only the vibrator 16 j 1 at the intersection, Driving becomes easy. The ultrasonic probe
of the present embodiment also has the same features as those of the above-described
embodiment. Next, one embodiment of the receiving system of the ultrasonic measurement
apparatus according to the present invention will be described. FIG. 1 shows a block system
diagram of one embodiment of the apparatus according to the present invention. The
configuration is the same as that of the receiver circuit of the electronic sector scanning method
used, but the delay tap selection information stored in the read only memory (ROM) in the delay
control circuit 21 is the unequal intervals of the ultrasonic transducers. In FIG. 10T, which is
different depending on the arrangement, 17 is an ultrasonic probe, and the above-mentioned
ultrasonic probe according to the present invention is used. Received signals that have been
subjected to sound-to-electric conversion from N ultrasonic transducers (not shown), which are
smaller in number than in the prior art, are respectively changed in gain according to the time
for attenuation compensation. 0 is applied to the delay circuit 19 via the gain control amplifier
1'8 to be applied, and this delay circuit 19 applies delay time independent of each other to each
of the input reception signals j11 to 71H. The respective delay times are variably controlled by
the output signal of the delay control circuit 21 to which the output of the focus position control
circuit 2o is supplied. Also, at this time, nine o'clock phase control is performed in consideration
of the unequally spaced arrangement of the ultrasonic transducers constituting the ultrasonic
probe 17 0 in this way, and delayed by the delay circuit 19 and taken out The received signals
vg1 to van are supplied to the adder circuit 3 snow and added and synthesized. 0 This
synthesized signal is an ultrasonic wave received signal from a specific incident direction or a
specified depth point designated by the focus position determination circuit 20. The operation of
0 or more, which is output from the output terminal 23 and displayed and recorded, is
performed for each scanning angle. In the case of transmission as well as in the case of reception
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above, a drive-phase between the delay of the drive signal and a gap between the drive signal
taking into account the non-equidistant arrangement of N ultrasonic transducers in the ultrasonic
probe 17 as in the above reception. In the case of 0 where the direction of travel of the
synthesized wave front of each ultrasonic transducer can be controlled from K by variable
control, FIG. 3 and v. In the case of the ultrasonic probe shown in FIG. 4, the ultrasonic waves are
emitted above the ground electrode 8 and scanned in a fan shape as described above, whereas
the ultrasonic waves shown in FIGS. In the case of the probe, the ultrasonic waves wither in the
direction of Sakura in the space in the upper direction in both figures.
□ As described above, according to the present invention, the shape of each transducer
constituting the ultrasonic probe is approximately cylindrical or spherical, so that the directivity
characteristics of transmission / reception of ultrasonic waves can be made conventional.
Compared with the prior art, the total size of the transducers can be reduced compared to the
conventional one with a size that is relatively wide and therefore can be machined with a finite
size, so that it is possible to configure at low cost. Because they are arranged at intervals, the
ultrasonic beam i degree, EndPage: 4 beam focusing, etc. are uniform over the entire deflection
angle range, and grating lobes can be reduced. In addition, since this ultrasonic probe is used, the
total number of drive circuits and delay circuits of the ultrasonic measurement apparatus can be
reduced, so that it can be configured at low cost, and since it has few ging lobes, high quality is
achieved. Sound wave information can be measured.
4. Brief description of the drawings Fig. 1 (At ', (Bl shows the ultrasonic radiation energy
characteristics (directive characteristics) of the transducers in the conventional and the present
invention ultrasonic transducers, Fig. 2 FIG. 3 is a view for explaining the generation of grating
lobes, FIG. 3 and FIG. 4 are respectively a cross-sectional view and an external perspective view
of an embodiment of an ultrasonic probe according to the present invention, and FIG. The figures
are respectively a cross-sectional view of an essential part of another embodiment of the
ultrasonic probe according to the present invention, and an external perspective view 11117 is a
block system diagram showing an embodiment of a receiving system of the ultrasonic measuring
apparatus according to the present invention. is there. 1s4ets 11 to 16s 4 ··· Ultrasonic
transducer, S · · · Drive electrode, 6 · · · Substrate · 7 · · · Flexible piezoelectric film, 8 ° 15 · · ·
Ground electrode, 91 to 9s · · · Spacer, 10.12 ... electrode, 11 ... multilayer printed board, 14 ...
flexible piezoelectric material, 17 ... ultrasonic probe, 21 ... delay control circuit 0 Patent
applicant Fujitsu, Ltd. Attorney Attorney Co., Ltd. Hiroshi Matsuoka $ -r-alt,: ,,,, 'L · EndPage: 5
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