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JP2002336248

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2002336248
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic probe suitable for ultrasonic imaging in the harmonic echo method.
[0002]
2. Description of the Related Art In recent years, harmonic echo methods that receive ultrasonic
waves at harmonics of transmitted ultrasonic waves (generally twice the frequency of transmitted
waves) and form an image based on the received signals have attracted attention. The harmonic
echo has preferable characteristics such as a sharp main lobe and a low side lobe as compared
with the fundamental wave echo, and the image quality is expected to be improved by the
harmonic echo method.
[0003]
SUMMARY OF THE INVENTION In order to realize the harmonic echo method with a single
transducer, a broadband transducer having a wide range of signal components from the
transmission frequency to the double of the reception frequency is required. However, there is a
problem that such a wide band transducer is difficult to manufacture and causes cost increase.
Also, in this case, since both the transmission frequency and the reception frequency can not be
made the best part of the sensitivity (power) characteristic of the vibrator, the level of the
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harmonic echo signal also becomes low, and the luminance level of the image becomes low.
There is a problem of being prone.
[0004]
In order to achieve the above object, an ultrasonic probe according to the present invention
comprises a transmission transducer for transmitting an ultrasonic wave at a fundamental
frequency, and a harmonic of the fundamental frequency. And a receiving transducer for
receiving ultrasonic waves of a wave frequency, wherein the transmitting transducer and the
receiving transducer are arranged in a concentric structure.
[0005]
Here, "a transducer for transmission of ultrasonic waves at a fundamental frequency" means a
transducer having good sensitivity (electro-mechanical conversion efficiency) of ultrasonic waves
at a fundamental frequency.
The same applies to the description of the receiving vibrator. In this configuration, the concentric
structure has an advantage that the transmission axis and the reception axis of ultrasonic waves
can be made to coincide.
[0006]
In a preferred aspect of the present invention, as the concentric structure, a structure is
employed in which the transmission transducer is on the outside and the reception transducer is
on the inside.
[0007]
Further, in the present invention, the transmitting vibration and receiving vibrators are formed
using a piezoelectric body made of PVDF (polyvinylidene difluoride).
Because PVDF has small lateral vibration, it is not necessary to take measures against ultrasonic
leakage such as separating the transducers and resin molding between them, and a compact
transducer structure can be configured.
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[0008]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present
invention (hereinafter referred to as embodiments) will be described based on the drawings.
[0009]
FIG. 1 is a perspective view schematically showing the configuration of a transducer portion of
an ultrasonic probe according to the present invention.
This transducer structure can be used, for example, as a mechanical sector scanning probe.
[0010]
As illustrated, in the present embodiment, a transducer having a concentric structure including a
circular receiving transducer portion 20 and a donut-shaped transmitting transducer portion 10
surrounding the periphery is used. The transmitting vibrator unit 10 is configured as a vibrator
having a good sensitivity (electro-mechanical conversion efficiency) at a predetermined
frequency f (referred to as a fundamental frequency), and the receiving vibrator unit 20 has twice
the fundamental frequency. It is configured as a transducer with a good sensitivity at a frequency
of 2 f. Here, "good sensitivity" at frequency f indicates, for example, a situation such as the center
frequency or the maximum sensitivity point frequency being in the vicinity of the frequency f.
[0011]
FIG. 2 is a view schematically showing a cross section of this vibrator portion. As shown, the
vibrator portion of the present embodiment includes a doughnut-shaped transmitting
piezoelectric element 12 and a circular receiving piezoelectric element 22 inside the transmitting
piezoelectric element 12, and one side of the both piezoelectric elements 12 and 22 is provided.
The common electrode 30 is attached to the surface. The other side of the transmitting
piezoelectric element 12 is provided with a transmitting signal electrode 14 according to the
shape and size of the element 12, and the other side of the receiving piezoelectric element 22 is
formed in the shape and size of the element 22. A combined reception signal electrode 24 is
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provided. The transmission signal electrode 14 and the reception signal electrode 24 are
electrically separated, and the transmission piezoelectric element 12 and the reception
piezoelectric element 22 can be individually driven.
[0012]
In this configuration, the transmitting piezoelectric element 12 and the receiving piezoelectric
element 22 are both formed of PVDF (polyvinylidene fluoride), which is a type of polymeric
piezoelectric material. The difference between the high sensitivity frequencies of the transmitting
transducer portion 10 and the receiving transducer portion 20 can be realized by changing the
thickness of the piezoelectric elements 12 and 22. That is, if the PVDF sheets of the thickness
corresponding to the desired frequency are cut out and combined into the shapes (circular or
donut shape) of the transmitting and receiving piezoelectric elements, respectively, the vibrator
portion of this embodiment can be formed. It should be understood that FIG. 1 and FIG. 2 are
merely schematic views, and the size and thickness ratio of each of the piezoelectric elements 12
and 22, and each of the electrodes 14, 24, and 30 are not necessarily as they are.
[0013]
PVDF has a characteristic that the transverse vibration component is extremely small as
compared with PZT, which is a commonly used piezoelectric material, and therefore, the
transmission electric element 12 and the reception piezoelectric element 22 are different. Signal
leakage (interference) between them is hardly considered. Therefore, there is no need to take
measures against leakage such as separating the two piezoelectric elements 12 and 22 from each
other and molding the space with resin or the like, so that simplification and downsizing of the
structure can be achieved.
[0014]
FIG. 3 is a functional block diagram showing a schematic configuration of the ultrasonic
diagnostic apparatus according to the present embodiment. The probe 100 is of a mechanical
sector scanning type provided with the transmission transducer portion 10 and the reception
transducer portion 20 of the concentric structure described above. A drive pulse is supplied from
the transmission circuit 202 of the ultrasonic diagnostic apparatus main body 200 to the signal
electrode 14 of the transmission transducer unit 10, whereby the transmission transducer unit
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10 mainly has the frequency f corresponding to the thickness thereof. It emits ultrasound. The
ultrasonic wave emitted from the transmission transducer portion 10 passes through the
acoustic matching liquid and the aperture film (not shown) of the probe, enters the object, is
reflected in the object, and is received. Received at 20. The transducer unit for reception 20 is
highly sensitive to the second harmonic (frequency 2 f) of the transmission ultrasonic wave, and
outputs a reception signal representing an echo of frequency 2 f. The reception signal is
subjected to amplification and other signal processing in the reception circuit 204, and is then
supplied to the image forming unit 206 to form a tomographic image or the like in accordance
with the scan. As a result, it is possible to obtain a high-quality ultrasound image using second
harmonic components.
[0015]
Here, FIGS. 1 and 2 show the case where the transmitting transducer portion 10 and the
receiving transducer portion 20 are arranged in a plane for the sake of simplicity. However, the
ultrasonic radiation of both the transducer portions 10 and 20 It is also preferable to adopt an
arrangement in which the wave receiving surface is concave so that the focusing effect of the
ultrasonic wave can be obtained.
[0016]
Note that since the transmission transducer unit 10 can also receive an echo, the reception signal
of the transducer unit 10 can also be used for image formation in the image forming unit 206 via
the reception circuit 204.
As a result, various functions such as switching and displaying the image of the second harmonic
(2f) echo and the image of the fundamental (f) echo, or superimposing, combining and displaying
both simultaneously, etc. Can be realized. Also, by thus enabling the probe 100 to output a
reception signal mainly composed of the fundamental wave (f) echo component received by the
transmission transducer unit 10, the general purpose of the probe 100 itself is There is also an
advantage of increased sex.
[0017]
As described above, according to the probe of this embodiment, first, the transducer portion is
combined with the transmission transducer portion 10 of the fundamental frequency f and the
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reception transducer portion 20 of the second harmonic frequency 2f. With this configuration,
high sensitivity can be realized for both transmission and reception. Both the transmitting
piezoelectric element 12 and the receiving piezoelectric element 22 are easy to manufacture as
described above, and it is also easy to assemble them into the structure as shown in FIGS. As
described above, in the present embodiment, the probe for harmonic echo can be configured at
lower cost and easier than the configuration using a wide band single transducer.
[0018]
Further, in the present embodiment, the transmitting transducer axis of transmitting ultrasound
and the receiving ultrasound of receiving ultrasound are made to coincide with each other by
making the transmitting transducer section 10 and the receiving transducer section 20 have a
concentric structure. It has the merit of being able to
[0019]
Further, in the present embodiment, since the receiving transducer portion 20 is disposed inside
and the transmitting transducer portion 10 is disposed outside thereof, the echo tends to easily
converge on the receiving transducer portion 20, and an improvement in the reception
sensitivity can be expected. .
[0020]
The preferred embodiment of the present invention has been described above. However, the
above-described embodiment is merely an example of the application example of the present
invention, and various modifications can be made within the scope of the present invention.
[0021]
For example, in the above embodiment, the concentric “circle” structure in which the circular
receiving transducer portion is surrounded by the donut shaped transmitting transducer portion
is adopted, but other general concentric structures are the same as above or An effect close to
the above can be obtained.
As an example of the concentric structure, for example, there is a concentric rectangular
structure surrounded by a rectangular transmission transducer portion having a hole in which
the shape of the rectangular reception transducer portion is matched to the rectangular shape.
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It is preferable from the viewpoint of area efficiency and the like that the outer vibrator portion
has a hole matching the inner vibrator portion, but the outer peripheral shape of the outer
vibrator portion is the inner vibrator portion. It is not necessary to be consistent with the shape.
[0022]
Furthermore, although the above embodiment has an arrangement structure in which the
receiving vibrator portion is inside and the transmitting vibrator portion is outside, the effects
similar to the above embodiment, such as the matching of transmission and reception axes, can
be obtained by reversing this. can get.
[0023]
Further, in the above embodiment, the configuration has been exemplified in which the focusing
effect of the ultrasonic wave is obtained by arranging each transducer unit so that the
transmitting and receiving surfaces thereof are concave. It is also preferable to arrange a
plurality of transmission transducer portions concentrically at the outer side of the above, and
electronically control excitation of each of the transmission transducer portions to perform
electronic focusing.
[0024]
As described above, in the ultrasonic probe according to the present invention, the harmonic
transducer method is realized by arranging the transducer for transmission and the transducer
for reception in a concentric structure. While being able to manufacture easily the high
sensitivity probe for this at low cost, the transmitting axis of an ultrasonic wave and the receiving
axis can be made to correspond.
[0025]
Brief description of the drawings
[0026]
FIG. 1 is a perspective view schematically showing the structure of a transducer portion of an
ultrasonic probe according to an embodiment.
[0027]
FIG. 2 is a schematic cross-sectional view of a transducer structure of the ultrasound probe of the
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embodiment.
[0028]
FIG. 3 is a view showing an entire configuration of an ultrasonic diagnostic apparatus using the
ultrasonic probe of the embodiment.
[0029]
Explanation of sign
[0030]
DESCRIPTION OF SYMBOLS 10 transmission vibrator part, 12 transmission piezoelectric
element, 14 transmission signal electrode, 20 reception vibrator part, 22 reception piezoelectric
element, 24 reception signal electrode, 30 common electrode.
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