JPS5656288

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DESCRIPTION JPS5656288
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing the appearance of the probe,
FIG. 2 is a view showing a cross section of a conventional probe, and FIG. 3 is an ultrasonic beam
obtained by the conventional probe FIG. 4 is a view showing an embodiment of the probe
according to the present invention, and FIG. 5 is a view showing the directivity of an ultrasonic
beam obtained by the probe according to the present invention. is there. DESCRIPTION OF
SYMBOLS 2 ... acoustic lens, 3 ... ultrasonic transducer ¦ vibrator, 4,5 ... electrode, 6.7 ... lead ¦
read ¦ reed 8 ... front alignment layer, 9 degree 10 ... case part.
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasound
probe. The directivity of the ultrasonic beam is one of the factors affecting the sharpness of the
tomographic image obtained by the ultrasonic diagnostic apparatus. In the conventional
ultrasonic probe (hereinafter referred to as a probe in terms of rate), an acoustic lens is provided
in the transmission direction so that the transmitted ultrasonic waves are focused by a thin beam,
and directivity is improved. The However, the ultrasonic beam emitted by the conventional probe
f- is not always satisfactory because the left and right are asymmetric with respect to the central
beam. It can not be said that the directivity to 'J was obtained. As a result, ultrasonic echoes are
reflected from unnecessary parts of the object due to the spread of the ultrasonic beam, which is
one cause of the smear of the tomographic image. The present invention is an improvement on
this point and provides a more directional probe f than the conventional one. FIG. 1 is a view
showing the mantle of the probe. In FIG. 1, 1 is a main body of a probe and 2 is an acoustic lens.
The ultrasonic wave transmitted from the main body 1 propagates in the y direction as shown in
FIG. 1 so that the beam of the ultrasonic wave is focused at the focal point 01 of the acoustic lens
2. The X direction in FIG. 1 indicates the scanning direction, and the purpose of the improvement
in the present invention is to reduce the ultrasonic beam spreading in two directions. FIG. 2 is a
cross-sectional view of a conventional probe. In FIG. 2, 2 is an acoustic lens made of, for example,
silicon rubber, and 3 is an ultrasonic transducer made of, for example, a PZT (lead zirconate
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titanate) -based element. The electrode provided on the 4.5 Fi ultrasonic transducer 5 has a
structure in which the electrode 4 wraps around a part (2) of the other surface as shown in FIG.
The electrode structure of the present invention has the advantage of being able to connect the
electrodes with only one wall. 6.7 are leads connected to the electrodes 4 and 5, respectively. 8 #
'i Front matching layer, which has the effect of improving ultrasound matching? , 1 o Fi case part.
In the probe shown in FIG. 2, the conventional one is the focal point (center line) of the acoustic
lens 2 on the center of the mechanical distance formed by the case portion 9.10, that is, 0 in FIG.
) Were arranged to match. The directivity of the ultrasonic beam obtained by the conventional
probe as shown in FIG. 2 is known as the fifth factor. That is, in the fifth factor, the position of
the central beam has a peak value, but the characteristics are asymmetric between the right and
left with respect to the central beam. The cause of the asymmetry of the directivity is
investigated, and the solution is described below.
In FIG. 2, the acoustic lens 2 is described in the related art in which the focal point is placed on
the case portion 9, 100 mechanical center rod, but in the ultrasonic transducer S of FIG. The
center of motion does not coincide with the mechanical center line. In the ultrasonic transducer S
of FIG. 2 (3), since the electrode 4 is wound to one surface as shown in FIG. Ultrasonic waves are
not transmitted. Accordingly, the ultrasonic waves are transmitted from the portion (-1 of FIG. 2),
and the center of the transmission is the line of (b) of FIG. The cause of directivity asymmetry is
due to the fact that the focal point of the acoustic lens 2 is not aligned with the vibration center
line, ie, (b) in FIG. FIG. 4 shows an embodiment of a probe according to the present invention as
means for solving directivity asymmetry. In FIG. 4, the acoustic lens 2 is provided such that its
focal point is necked on the center line of the vibration ←). The configuration of the other probes
is the same as that of FIG. 2, so that the elements of FIG. An example of measurement of the
directivity of the ultrasonic beam obtained from the probe of FIG. 4 is shown in FIG. The
directivity shown in FIG. 5 has substantially the same characteristics on the left and right with
the central beam as the axis of symmetry. In FIG. 5, the distance between two points (4) at which
the 20 dB ultrasonic beam is reduced from the central beam is t3. Let the distance between two
points reduced by the same <4 oam be t4. Similarly, in the fifth section, the distance t-1 between
two points where the 20 dB ultrasonic beam is reduced from the central beam. The distance
between the same two points reduced by 40 dB is t2. When the values of t1 to t4 are compared
with the measured values, η == 0.87. M ′ ′ = 0.661, FIG. It can be seen that the directivity of
the probe force, 6 gain 61.6 ultrasonic two wave beam is sharp in two directions. As described
above, the point of the present invention is that the focal point of the acoustic lens 2 is on the
center (← in FIG. 4) of the section (& in FIG. 4) where the ultrasonic transducer 5 actually
vibrates. However, in practical terms, the position of the overhead lens 2 may be substantially on
the fourth division (ro) line if it has a focal point. That is, it is effective in the symmetry of
directivity if the scorching of 1 acoustic lens 2 is within the range from the gradient −) line to
the scale − according to the actual measurement. As described above, according to the present
invention, it is possible to sharpen the directivity of the ultrasonic beam by a simple procedure of
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merely moving the position of the acoustic lens of the conventional probe (5). Ultrasonic
tomographic image can be obtained, the effect of the seven is extremely large.
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