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TECHNICAL FIELD OF THE INVENTION The present invention relates to an ultrasonic pump used
for transmitting and receiving ultrasonic waves, and more particularly to effectively attenuate
multi-reflected waves to improve S / N. Background of the Invention In a conventional
mechanical scanning ultrasonic probe, since the transducer can not be in direct contact with the
living body because the transducer is rotated and oscillated, ultrasonic waves are transmitted
between the transducer and the living body A liquid for cooking (Virgin 2-in, water, etc.) is used.
Furthermore, as a pig for 147 months of this liquid, synthetic 161 fats such as rubber and
polyethylene are used, but all do not emit ultrasonic waves to the living body? , + 11! Choose a
low loss of i), r <4.7, select a low-accumulated moon, and make the eye and thickness as thin as
possible. In the case of the electronic scanning ultrasonic probe, the transducer does not move,
so it can be directly applied to the living body. Therefore, although a film such as a mechanical
scanning type is generally unnecessary, a silicon non-comb or the like may be used for the
purpose of protecting the vibrator 1 or forming a sound W sound. However, in this case as well,
there is no change in the tendency to reduce the film thickness by using November with small
attenuation. Prior art and problems The conditions of element H used as conventional liquid
moonscopy or vibrator protective film etc. are firstly acoustic / impedance or close to that of the
observation object, which is opposite or small, and secondly attenuation is It is small. As an
example, the attenuation value of g / recon "1 person is shown, and IjTf 1 3 3 伺 5 M II Z 約 1 r
approximately 1 (] B / ll 1 m 'Q;' r ') Z +,> IJ-r: Since the thickness of the r-m is limited to about
1.5 最大 at the maximum, the attenuation is 1.5 d B in progress. In general, since the reflection
from the living body is extremely weak, reducing the attenuation of the ultrasonic wave
transmitted through this type of film is particularly advantageous for observation of the low
depths of the low level: 2-level. However, in recent years, with the improvement of vibrators and
electronic circuits, it has become possible to receive even weak signals with a margin, and
therefore, the use of a film with small attenuation is not essential condition. One of the things
that degrades the image quality is multiple reflections between the transducer and strong
reflection pairs in the living body. This multiple reflection degrades the S / N. According to the
experimental results, in the human body, there is a particularly strong reflective layer in the
range of 20 open from the body surface. When the transducer is observed, the acoustic
impedance of the piezoelectric element is about 20 times that of the human body, so that the
ultrasonic waves incident on the transducer are mostly reflected. From this, in the conventional
film which places an emphasis on reducing the attenuation between the transducer and the
human body, multiple reflections between the transducer and the reflection layer near the body
surface are received by the transducer and become noise.
For example, when observing the heart, this kind of noise appears near the septum. FIGS. 3 and 4
show the eyelids 1 of the present invention. In FIG. 4, an IL or ultrasonic transducer, 2 is a
membrane of 141 dB attenuation, 3 is a body surface, 4 is a strong reflection old at an open 20
(the body surface is 0). 5 is a septum located in the lower body surface 401111. Among the
ultrasonic waves Δ and B simultaneously transmitted from the vibration J ′ I, it is assumed that
the first reflection is received jJ by the reflection layer where Δ is at the position of depth 2011
IN. The waveform obtained at this time is shown by ▪ in FIG. 3, and its reflection 1 / bell is
extremely high (the one with a perfect reflector is represented by □ d 13) and the ultrasonic
wave 13 is 2 When reflected by the septum 5 at a depth of (+ η), it is received as a waveform @
of around -G I d B. On the other hand, when the anti-law wave 11 is reflected by 11 highreflection waves r1 and directed to the reflection layer 4 and reflected A from the layer 4, each 2
· time 1 反 1- The anti-law wave is received at the same time as the vibration + J + 1 + Fl + iii +
sentence wave @ @, the two good-looking anti-law wave @ Lechel (−60-2α) dR Take 2 car Leh
Le (2) The difference 2ty with -60 -4 (alpha) differs from ty -'l d13 by 2 (alpha) -3 (1B). Since the
S / N is not good after this, the observation of the reflected wave @ becomes an exception. The
object of the present invention is to improve multiple reflected waves lti, attenuating L 'and S / N
by using a layer (film) which attenuates ultrasonic waves positively contrary to the prior art. It is.
The ultrasonic probe according to the present invention is characterized in that an attenuation
layer having an acoustic impedance approximately equal to that of the observation object and an
attenuation of at least 3 dB in one way is provided between the ultrasonic transducer and the
observation object. However, this will be described in detail with reference to the illustrated
embodiment. Embodiment 1 of the Invention FIG. 1 shows an embodiment of the present
invention applied to an ultrasonic probe 10 of mechanical scanning type. Is an ultrasonic
transmission medium accommodated between them, and J4 is an attenuation film. As the
material of the m decay film 14, the acoustic impedance is close to the living body and the
attenuation is large. In order to make the film thickness thin and to make the attenuation large,
fine particle mixing is good. Metals such as Kungsten, aluminum, etc., or crows, plus polystyrene,
polyethylene, etc., as micro 1 'ij of wavelengths other than the ultrasonic wave, mixed in with siri]
l ngono ·, to increase attenuation Is suitable for this type of membrane. Attenuation + 1 One-way
attenuation α of AI4 is set to 5 (5) f3 or more.
This is to set the difference between the target reflected wave and the five-multiple reflected
wave, which is described above, to 2 dB or more by 6 dB (to improve the S / N). The attenuation
film 14 simultaneously attenuates the target anti-UJ wave as well. The upper limit of Y depends
on the capacity of the reception amount M3 or the like. The surface, the damping film 14 may be
adhered to the surface of the j peristaltic r1, and the tip α 11.1 of the envelope 10 may be
closed by the crotch of the eyelid. FIG. 2 shows another embodiment of the present invention
applied to the electronic scanning ultrasonic probe 15, wherein A 'is a transducer divided for A'r
knee 1' J1 vibration r or electronic scanning. In this case, the tip of the envelope 16 is reduced by
g 115 i! Bond 14-(I have. At this time, heino may be focused [..., A concave or convex surface may
be formed on the attenuation film 14 to be a lens. Effect of the Invention As described above,
according to the present invention, an attenuation film having a large amount of attenuation is
interposed between the transducer and the observation object-U-U n-th multiple reflected waves
pass 2 n times through the attenuation film Since it is attenuated by 2 n times, it becomes
possible to lower the level of reflection from reflection from a distant observation object
returning to the oscillator at the same time as the second and third times ..... is there.
Brief description of the drawings
1 and 2 are block diagrams showing an embodiment of the present invention, and FIGS. 3 and 4
are explanatory views of multiple reflection.
In the figure, 1 is an ultrasonic transducer, 3 is an observation object surface, 1 (1, 15 is an
ultrasonic probe, 14 is an attenuation film. Applicant: Fujitsu Limited Attorney Attorney Akira
Atsushi Yanagi Figure 1 Figure 2 Figure 3 Figure 6
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