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Description 1, title of the invention
Ultrasound probe
The present invention relates to the structure of an ultrasonic probe, and more particularly to the
improvement of a probe having a structure in which the Q of the ultrasonic transducer is lowered
by adopting a stagger method. Heretofore, an ultrasonic probe using a piezoelectric element such
as lead zirconate titanate (-PZT) has been known. The ultrasonic wave generated from this
transducer depends on its thickness, and generally the thickness is changed to obtain an
ultrasonic wave of a desired frequency. By the way, in order to improve the distance resolution in
the pulse echo method of emitting an ultrasonic pulse and knowing the condition of the object by
its reflected wave, it is desirable that the emitted pulse be short 1 for this purpose. You should
lower it. As a method, there is a stagger method in which a plurality of vibrators having different
resonance frequencies are driven simultaneously. As a vibrator used for the stagger method, an
ultrasonic apparatus using one having a different resonance frequency with a slightly different
thickness is conventionally known. However, it is difficult to create a plurality of transducers
each having a slightly different thickness. In particular, in the case of applying this stagger
method to an electronic scanning system such as a linear mirror, it is necessary to arrange
narrow transducers of about 03 to 1.0111 in parallel at equal intervals and uniformly in parallel.
It becomes difficult when the characteristic of the obtained ultrasonic probe is degraded, K. Still,
if the plane opposite to the ultrasonic radiation plane of the transducers having different
thicknesses is placed on one plane, the ultrasonic directivity of each transducer is adversely
affected. Therefore, in order to obtain good directivity, it is necessary to align the ultrasonic
radiation surface, in which case it is necessary to match the support base to the thickness of the
transducer, which makes it more difficult to manufacture EndPage: 1. The characteristics of the
acoustic probe will be degraded. The present invention has been made in view of the problems of
ultrasonic probes that adopt these conventional stagger methods, and it is an object of the
present invention to obtain an ultrasonic probe with good ultrasonic characteristics. In the
present invention, the thickness resonant frequency of the ultrasonic transducer is thick!
Focusing on the fact that it depends not only on the width of the vibrator, but also on the width
of the vibrator), and has a feature in that the stagger method is realized by simultaneously
driving a plurality of vibrators whose widths are gradually changed. That is, as shown in FIG. 1,
with respect to the ultrasonic transducer (1) having a length 41 width W1 thickness t41, the
variation frequency and the width of the imaging element with respect to the width-thickness
ratio (W / l) are very large. When the ratio (f1 / fo) of the resonance frequency in the case is
examined, the width W affects the thickness resonance frequency and becomes low if the width
W becomes less than or equal to the thickness, and if @W becomes smaller again It turned out
that it became fo.
By changing the width using this phenomenon, the thickness resonance frequency is changed.
Hereinafter, examples of the present invention will be described. FIG. 2 is a circuit configuration
diagram of an apparatus in which a stagger method is adopted in a linear scan type ultrasonic
diagnostic apparatus and three transducers having different resonance frequencies are
simultaneously driven. The pulse generated at the pulser 0 [across the closed electronic switch 0
各 々 and the respective resonant frequencies f 1. f2. The three ultrasonic transducers (12a),
(12b)-(12c), (12a9, (12b '), (12c),... of f3 are driven, and ultrasonic pulses are emitted from these
transducers. Ru. An ultrasound probe a2 is configured by these ultrasound transducers. The
reflected wave from the object is again received by the same transducer and appropriately
processed in the receiving circuit 03) through the same electronic switch and displayed on the
display circuit I. Since the electronic switches 0υ are sequentially switched one by one or plural
ones, a cross-sectional image can be obtained in the display circuit I. By the way, as shown in FIG.
3 as a vibrator of this apparatus, the width is W1, W2. Different transducers of W3 are provided
in parallel. The width of each vibrator is set to Wl 20, 6 朋, W 2 = 0.5 朋, W 3 = 0.4 、, and the
resonance frequency of the vibrator of each width is f 1 = 2.2 MHz 1 f 2 = 2. 35 MHz, f 3 = 2 In
the case of .5 MHz, the overall Q could be lowered to about 7 by changing the width of each
transducer whose Q was about 15. By the way, as shown in FIG. 2 and FIG. 3, when vibrators
having different widths 1.1 are provided in parallel, their orderliness is + w, so the submaxima
(side lobes) in the ultrasonic directivity are large. May be In such a case, if the arrangement of
the transducers in FIG. 2 is as random as possible as shown in the fourth section, the submaxima
can be reduced. This is effective not only in the present invention for driving a plurality of
transducers having different widths, but also in the stagger method using a plurality of
transducers having different thicknesses in the prior art. In the above-described lightening, the
one which simultaneously drives three vibrators having different resonance frequencies is
described, but of course the invention is not limited to three. Further, the present invention can
be applied not only to an apparatus adopting the laser scanning method but also to an apparatus
of mechanical scanning. As described above, according to the present invention, since the
resonance frequency is changed little by little by changing the widths of a plurality of vibrators
driven simultaneously, the thicknesses of these vibrators are all the same, and the combination of
the vibrators is easy Thus, an excellent ultrasound probe of characteristics is obtained.
4. Brief description of the drawings Fig. 1 shows the dimensions of the vibrator,-Fig. 2 is a circuit
diagram of the ultrasonic diagnostic device of the linear can electronic scanning key which
adopts the stagger method, and Fig. 3 is the present. FIG. 4 is a perspective view of an ultrasonic
probe according to the invention-embodiment, and FIG. 4 is a diagram showing a transducer
arrangement according to another embodiment of the present invention. 12a, 12b, 12c, 12a ',
12b', 12c '... ultrasonic transducer agent patent attorney Akira Tomioka (other one) EndPage: 2
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description, jps52150615
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