close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2015188121

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2015188121
Abstract: An ultrasonic probe capable of obtaining a high-resolution diagnostic image by
optimizing an acoustic matching layer to obtain a wide-band, smooth frequency characteristic
and a short pulse length characteristic. Provide a child. SOLUTION: A wide band and smooth
frequency characteristic is obtained by configuring at least one of a plurality of acoustic
matching layers provided on one surface of a piezoelectric element to be a mixture of a resin
material and an elastomer material. And the pulse length is short. [Selected figure] Figure 1
Ultrasound probe
[0001]
The present invention relates to an ultrasound probe used to obtain diagnostic information of a
subject by transmitting and receiving ultrasound waves to a subject such as a living body.
[0002]
The ultrasonic diagnostic apparatus transmits ultrasonic waves into a subject of a living body
such as a human or an animal, detects a reflection signal reflected within the living body, and
displays a tomogram or the like of tissue in the living body on a monitor. Provide information
needed for the diagnosis of
At this time, the ultrasonic diagnostic apparatus uses an ultrasonic probe as a sensor for
transmitting ultrasonic waves into the subject and receiving a reflection signal from the inside of
14-04-2019
1
the subject.
[0003]
FIG. 10 shows an example of such an ultrasound probe. In FIG. 10, the ultrasonic probe 100 has
a plurality of piezoelectric elements 11 arranged to transmit and receive ultrasonic waves to and
from an object (not shown), and a front surface of the piezoelectric element 11 on the object side.
An acoustic matching layer 12 (12a, 12b, 12c) comprising one or more layers (three layers in
FIG. 10) provided in the (Z direction in FIG. 10) and an acoustic lens provided on the object side
surface of the acoustic matching layer 12 13 and a back load material 14 provided on the back
side opposite to the acoustic matching layer 12 with respect to the piezoelectric element 11.
[0004]
Electrodes (not shown) are respectively disposed on the front and back surfaces of the
piezoelectric element 11, and a voltage is applied to the electrodes to vibrate the piezoelectric
element 11 to transmit and receive ultrasonic waves, and transmit and receive them using
electrical signals. .
[0005]
The piezoelectric element 11 is formed of a piezoelectric ceramic such as PZT, a single crystal
such as PMN-PT, a composite piezoelectric of a composite of the above material and a polymer,
or a piezoelectric of a polymer represented by PVDF or the like. The voltage is converted into
ultrasonic waves and transmitted into the subject, or echoes reflected in the object are converted
into electrical signals and received.
In the illustrated example, a plurality of piezoelectric elements 11 are arranged in the X direction.
A plurality of arrays of such piezoelectric elements 11 are of the so-called electronic scanning
type in which ultrasonic waves are scanned electronically, and an ultrasonic beam can be
deflected or focused by phase control, and it is further electronically The plurality of piezoelectric
elements 11 are sequentially switched and scanned to form an ultrasonic tomographic image in
real time. In addition, there is also a method of mechanically scanning a single piezoelectric
element to form an ultrasonic tomographic image with almost no time difference.
14-04-2019
2
[0006]
The acoustic lens 13 serves to narrow the ultrasound beam in order to increase the resolution of
the diagnostic image. In the illustrated example, the acoustic lens 13 extends along the Y
direction (the direction orthogonal to the arrangement direction X of the piezoelectric elements
11) in the figure, and is formed in a smooth convex shape in the Z direction. I can squeeze. The
acoustic lens 13 is an optional element and is provided as needed.
[0007]
The back load member 14 is coupled to the piezoelectric element 11 to hold it, and further
serves to attenuate unnecessary ultrasonic waves. The back load member 14 is an optional
element and is provided as needed.
[0008]
The acoustic matching layer is provided to prevent a decrease in sensitivity and resolution
caused by the mismatch because the acoustic impedance difference between the piezoelectric
element and the object is large. In recent years, in order to realize higher resolution, studies are
being made on broadening the frequency, and one of the methods is to multilayer the acoustic
matching layer provided on the object side of the piezoelectric element with three or more layers.
See, for example, Patent Documents 1 and 2.
[0009]
The material of the layer on the subject side of the acoustic matching layer uses a thermosetting
material produced by crosslinking polystyrene with divinylbenzene having an acoustic
impedance value of 2.44 megarails as disclosed in Patent Document 1 And those using low
density polyethylene (LDPE) having an acoustic impedance of about 1.97 Mellars as shown in
Patent Document 2.
[0010]
In this specification, the X direction in the figure is also referred to as “arrangement direction
(of piezoelectric element)”, the Y direction as “width direction of (piezoelectric element)”, and
the Z direction as “thickness direction (of piezoelectric element)”. It shall be.
14-04-2019
3
[0011]
JP, 2003-125494, A JP, 2009-505468, A
[0012]
If the acoustic matching layer is made up of multiple layers, not only the broadening of the
frequency characteristics but also the form of the frequency characteristics will greatly vary
depending on how the value of the acoustic impedance of the acoustic matching layer provided
on the object side is selected. It greatly affects the resolution of the acoustic image.
For that purpose, it becomes important how to select the value of the acoustic impedance of each
layer of the acoustic matching layer and to use a material that conforms to the value.
As shown in the above-mentioned patent document 1, when a thermosetting material generated
by crosslinking polystyrene with divinylbenzene is used as a material of the layer on the subject
side in the acoustic matching layer, the acoustic provided on the subject side Because the
acoustic impedance of the matching layer is large, the low frequency range is endearing and
ripple has frequency characteristics, and the pulse length is also long, and even if the bandwidth
can be broadened, the depth of the living body of the subject with frequency dependent
attenuation. The degradation of resolution becomes remarkable from the shallow area.
Further, as the depth gets deeper, it further decreases and it becomes difficult to obtain a high
resolution image. Further, as shown in the above-mentioned Patent Document 2, when low
density polyethylene (LDPE) is used as the material of the acoustic matching layer on the subject
side of the acoustic matching layer, it is produced by crosslinking polystyrene with
divinylbenzene. While the acoustic impedance closer to the living body is obtained than the
thermosetting material, this material has weak adhesion, so peeling occurs due to temperature
change of the environment using the ultrasound probe or the environment carrying or storing
There are problems with quality because it is easy to do.
[0013]
Therefore, an object of the present invention is to provide a high quality ultrasonic probe capable
of obtaining a high resolution diagnostic image.
14-04-2019
4
[0014]
In order to achieve this object, the present invention provides a piezoelectric element having a
first surface and a second surface, and a first electrode and a second electrode connected to the
first surface and the second surface, respectively. An ultrasonic probe comprising an electrode
and an acoustic matching layer provided on the first surface, wherein at least one acoustic
matching layer of the acoustic matching layers is a mixture of a resin and an elastomer, To
achieve the intended purpose.
[0015]
Further, according to the present invention, the acoustic matching layer is composed of a
plurality of layers, and at least one acoustic matching layer is a layer present at a position most
distant from the piezoelectric element among the acoustic matching layers composed of a
plurality of layers. It may be a feature.
[0016]
Further, the present invention may be characterized in that only the layer present at a position
farthest from the piezoelectric element among the acoustic matching layers composed of a
plurality of layers is a layer composed of a mixture.
[0017]
Further, the present invention may be characterized in that the resin is styrene or a styrenemethyl methacrylate copolymer.
[0018]
Furthermore, the present invention may be characterized in that the elastomer is a synthetic
rubber or a natural rubber.
[0019]
The present invention may also be characterized in that the synthetic rubber is butadiene.
[0020]
Further, the present invention may be characterized in that the acoustic matching layer is
composed of a plurality of layers, and the acoustic matching layer composed of a plurality of
14-04-2019
5
layers is such that the acoustic impedance gradually decreases from the layer closer to the
piezoelectric element to the layer further away.
[0021]
Further, the present invention may be characterized in that the plurality of acoustic matching
layers are three.
[0022]
Further, according to the present invention, at least one acoustic matching layer is present at a
position farthest from the piezoelectric element in the acoustic matching layer, and the acoustic
impedance of at least one acoustic matching layer is 1.9 to 2.3 MEL It may be characterized by
being a range value.
[0023]
Further, according to the present invention, at least one acoustic matching layer is present at a
position farthest from the piezoelectric element in the acoustic matching layer, the resin is
styrene, the elastomer is butadiene, and the butadiene is mixed with styrene It may be
characterized in that the weight ratio is in the range of 3 to 29%.
[0024]
Further, the present invention may be characterized in that the acoustic matching layer is four
layers.
[0025]
Further, according to the present invention, at least one acoustic matching layer is present at a
position farthest from the piezoelectric element in the acoustic matching layer, and the acoustic
impedance of at least one acoustic matching layer is 1.8 to 2.28 mellars. It may be characterized
by being a range value.
[0026]
Further, according to the present invention, at least one acoustic matching layer is present at a
position farthest from the piezoelectric element in the acoustic matching layer, the resin is
styrene, the elastomer is butadiene, and the butadiene is mixed with styrene It may be
characterized in that the weight ratio is in the range of 4 to 40%.
14-04-2019
6
[0027]
Further, the present invention may be characterized in that the number of acoustic matching
layers is five.
[0028]
Further, according to the present invention, at least one acoustic matching layer is present at a
position farthest from the piezoelectric element in the acoustic matching layer, and the acoustic
impedance of the at least one acoustic matching layer is 1.6 to 1.8 Mellars. It may be
characterized by being a range value.
[0029]
Further, according to the present invention, at least one acoustic matching layer is present at a
position farthest from the piezoelectric element in the acoustic matching layer, the resin is
styrene, the elastomer is butadiene, and the butadiene is mixed with styrene It may be
characterized in that the weight ratio is in the range of 40 to 68%.
[0030]
The present invention may also be characterized in that a conductor foil electrically connected to
the first electrode is formed between the piezoelectric element and the acoustic matching layer.
[0031]
According to the present invention, a plurality of acoustic matching layers are provided on one
side of the piezoelectric element, and at least one of the acoustic matching layers is configured
using a mixture of a resin and an elastomer, thereby providing a wide band and smooth shape. It
is possible to obtain characteristics with short frequency characteristics and short pulse lengths,
obtain high-resolution diagnostic images, and provide high-quality ultrasonic probes with good
adhesion.
[0032]
1 is a schematic sectional view showing an ultrasonic probe according to a first embodiment of
the present invention. FIG. 3 is a schematic perspective view showing an ultrasonic probe
according to the first embodiment according to the present invention. And a diagram showing
the relationship between pulse length and a diagram showing the relationship between the
blending ratio of styrene and butadiene and the acoustic impedance, and a schematic perspective
view showing the ultrasonic probe according to the second embodiment of the present invention.
14-04-2019
7
Acoustic impedance of the fourth acoustic matching layer And a diagram showing the
relationship between the specific band and the pulse length, and a schematic perspective view
showing the ultrasonic probe of the third embodiment according to the present invention. A
diagram showing the relationship between the acoustic impedance of the fifth acoustic matching
layer and the relative band and the pulse length The schematic perspective view which shows the
ultrasonic probe of 4th Embodiment which concerns on this invention The schematic perspective
view which shows the structure of the ultrasonic probe which concerns on a prior art
[0033]
First Embodiment FIG. 1 is a schematic cross-sectional view showing an example of an ultrasonic
probe according to the present embodiment, and FIG. 3 is a schematic view showing an example
of an ultrasonic probe according to the present embodiment. It is a perspective view.
[0034]
The ultrasonic probe can be used by being electrically connected to the ultrasonic diagnostic
apparatus main body via a cable when configuring the ultrasonic diagnostic apparatus, and the
ultrasonic probe transmits and receives ultrasonic waves. Then, the received wave is converted
into an electric signal and transmitted to the ultrasonic diagnostic apparatus main body, an
image is generated by the signal processing unit in the ultrasonic diagnostic apparatus, and the
image is displayed by the display unit.
[0035]
The ultrasonic probe 10 transmits and receives ultrasonic waves using a piezoelectric ceramic
such as PZT, a piezoelectric single crystal such as PZN-PT, or a PMN-PT, or a composite
piezoelectric or the like in which the above material is mixed with a polymer. In the same manner
as the piezoelectric element 1, the ground electrode 5 provided on one surface of the
piezoelectric element 1 by evaporation or sputtering of gold or silver, or baking of silver, etc.,
evaporation or sputtering of gold or silver similarly to the ground electrode 5 A signal electrode
6 provided on the other surface opposite to one surface of the piezoelectric element 1, a signal
electric terminal 7 for signal extraction from the signal electrode 6, and the piezoelectric element
1 are mechanically held by baking of silver, etc. The back load material 3 has a function of
attenuating unnecessary ultrasonic signals as needed, and the acoustic matching layer 2 provided
on the ground electrode 5 of the piezoelectric element 1.
The ground electrode 5 is electrically connected to one surface of the piezoelectric element 1,
14-04-2019
8
and the signal electrode 6 is electrically connected to the other surface of the piezoelectric
element 1.
Three acoustic matching layers 2 (2a, 2b, and 2c from the side of the piezoelectric element 1) are
provided on one surface of the piezoelectric element 1 via the ground electrode 5.
In addition, the acoustic lens 4 is disposed on the acoustic matching layer 2 as needed.
Further, in the illustrated example, the piezoelectric element 1 and the acoustic matching layer 2
are individually divided, and a material such as silicone rubber or urethane rubber having a small
acoustic coupling in the part of the divided grooves Is filled.
Furthermore, an acoustic lens 4 is provided on the upper surface of the third acoustic matching
layer 2c using a material such as silicone rubber as necessary.
[0036]
This ultrasonic probe applies an electric voltage to the ground electrode 5 and the signal
electrode 6 from the main body of an ultrasonic diagnostic apparatus or the like, whereby the
ultrasonic wave generated by the mechanical vibration of the piezoelectric element 1 is the
acoustic matching layer 2 And is transmitted to the subject, and also receives a reflected wave
from the subject.
An ultrasonic probe for an ultrasonic diagnostic apparatus in which a living body is a subject is a
reflected wave transmitted from an organism by transmitting an ultrasonic wave to the living
body by direct contact with the living body or indirectly through an ultrasonic wave propagation
medium. Is received by the ultrasound probe again, the signal is processed by the main body, and
a so-called sensor is used for displaying and diagnosing a diagnostic image on the monitor.
[0037]
The first acoustic matching layer 2a may be made of a material having an acoustic impedance in
14-04-2019
9
the range of 8 to 20 megarails, such as silicon, quartz, glass such as fused quartz, machinable
ceramics, or graphite filled with metal powder. A material is used, and the second acoustic
matching layer 2b is made of a material having an acoustic impedance in the range of 3 to 8
megarails, for example, graphite or epoxy filled with filler such as metal or oxide in epoxy resin.
Use resin.
The third acoustic matching layer 2c provided on the object side, ie, the layer of the acoustic
matching layer 2 which is most distant from the piezoelectric element, is a mixture of at least two
kinds of materials including an elastomer material, for example, Preferably, a material obtained
by mixing an elastomeric material with a resin material is used, and the acoustic impedance has a
value in the range of 1.9 to 2.3 Mellars.
The mixture of the resin material and the elastomer material is made of a copolymer of the resin
material and the elastomer.
[0038]
The acoustic impedance of each acoustic matching layer decreases in order from the layer closer
to the piezoelectric element to the layer closer to the object.
The third acoustic matching layer 2c is made of a mixture containing an elastomeric material,
and thus has high adhesion.
Moreover, since it consists of a mixture of at least 2 types, an acoustic impedance can be suitably
adjusted with the compounding ratio.
[0039]
The reason why the acoustic impedance of the third acoustic matching layer 2c is preferably 1.9
to 2.3 Mellars will be described with reference to FIG.
FIG. 3 is a diagram showing the relationship between the acoustic impedance of the third
14-04-2019
10
acoustic matching layer 2c, the fractional band pulse length, and the frequency ratio band.
In FIG. 3, the horizontal axis represents the acoustic impedance of the third acoustic matching
layer 2c (unit: megarails), the vertical axis on the left is the pulse length (unit: μs), and the
vertical axis on the right is the frequency ratio band (bandwidth / center It represents the value
of frequency) (unit is a percentage).
[0040]
Here, the frequency is set to a center frequency of 7.5 MHz, the acoustic impedance of the back
load material 3 is 7 Mellars, the piezoelectric element 1 is a PZT-based piezoelectric ceramic, and
a material equivalent to PZT-5H is used. The acoustic matching layer 2a is located on the subject
side using a free-cutting ceramic having an acoustic impedance of 13 mellars, and the second
acoustic matching layer 2b using an epoxy resin filled with metal powder having an acoustic
impedance of 4 mellars. The frequency ratio band and the pulse length were calculated in a
configuration in which the acoustic impedance of the third acoustic matching layer 2c was varied
in the range of 1.6 to 2.6 Mellars.
The thickness of each of the first to third acoustic matching layers 2a, 2b and 2c was 0.25
wavelength.
In addition, the relative frequency band of the frequency characteristic is shown at -6 dB, and the
pulse length is shown at -6 dB, -20 dB and -40 dB levels.
The solid line in the figure indicates the frequency ratio band, and the broken line indicates the
pulse length at the level of -6 dB, -20 dB and -40 dB from the bottom, respectively.
[0041]
In FIG. 3, even if the acoustic impedance of the third acoustic matching layer 2c changes with a
pulse length of -6 dB, there is almost no large variation, but at -20 dB, the acoustic impedance
becomes smaller than 1.9 Mellars. And when the value becomes larger than 2.3 Mellars, the
value becomes relatively large, and at a level of -40 dB, the value becomes relatively large when
14-04-2019
11
the acoustic impedance becomes a value smaller than 1.7 Mellars .
Since the smaller the pulse length, the higher the resolution and the better the pulse length, it is
important to improve the resolution that the pulse length be small.
[0042]
On the other hand, with regard to the frequency ratio band of FIG. 3, the larger the value of the
ratio band, the deeper the resolution and the depth of examination.
In the case of a three-layer acoustic matching layer, it is desirable that the fractional band be 90
percent or more.
The specific impedance of the third acoustic matching layer 2c is 90% or more when the acoustic
impedance of the third acoustic matching layer 2c is 1.75 Mellars or more and 2.4 Mellars or
less.
It is desirable that the relative bandwidth be large and the pulse length be short for high
resolution, which means that the shape of the frequency characteristic becomes smooth and
becomes close to the form of a normal distribution, as shown in FIG. It is understood from the
results of both the characteristics of the specific band and the specific band that the acoustic
impedance of the third acoustic matching layer 2c is desirably in the range of not less than 1.9
Mellars and not more than 2.3 Mellars.
[0043]
Here, the mixing ratio in the case of using a mixture of styrene which is a resin material and
butadiene which is one of synthetic rubber materials as a material of the third acoustic matching
layer 2c is calculated using FIG.
FIG. 4 shows the relationship between the filling weight ratio of butadiene to styrene and the
acoustic impedance.
14-04-2019
12
In FIG. 4, the horizontal axis indicates the mixed filling weight ratio (unit is a percentage) in
which butadiene is mixed with styrene.
That is, a value of 0 on the horizontal axis indicates 100% of styrene, and a value of 100
indicates 100% of butadiene. Also, the vertical axis is represented by acoustic impedance (in units
of megarails).
[0044]
As can be confirmed from FIG. 4, the acoustic impedance of 100% of styrene (the value of 0 on
the horizontal axis) is 2.42 mellars, and the acoustic impedance of 100% of butadiene (the value
of 100 on the horizontal axis) is 1.37 mΩ. It is. It can be seen that by changing the mixing ratio
of butadiene to styrene, it is possible to obtain an arbitrary value between the acoustic
impedances of single styrene and single butadiene. When the mixing ratio of butadiene is, for
example, 5%, 10%, 20%, and 30%, the acoustic impedance of the mixture is 2.25 (sound velocity
2165 m / sec.) And 2.17 (sound velocity 2107 m / sec.). ), 2.07 (sound velocity 2028 m / sec.),
And 1.87 (sound velocity 1853 m / sec.). )メガレールスである。 In addition, the acoustic
impedance has measured the density and sound speed of the created material at 25 degreeC, and
has shown the value computed from density x sound speed.
[0045]
When the mixed filling weight ratio of styrene and butadiene is in the range of 1.9 to 2.3
megarails which is a preferable range of the acoustic impedance of the third acoustic matching
layer 2c, it is used for the third acoustic matching layer 2c The filling weight ratio of butadiene
mixed with styrene in the range of 3 to 29% is preferable, and it is preferable to mix butadiene
with styrene in this range.
[0046]
A mixture of styrene and butadiene has the advantage that it can be easily made into a film of
any thickness in the same way as filming a resin material, and it can be produced in extremely
large quantities with high precision, and also lowers costs. Can.
14-04-2019
13
In addition, since butadiene is mixed, adhesion is better than styrene alone, and a high quality
ultrasonic probe can be obtained.
[0047]
As described above, in the configuration in which the three acoustic matching layers 2 are
provided, a mixture of styrene and butadiene in any mixing ratio is used as the third acoustic
matching layer 2 c provided on the object side. Since it is possible to obtain a wide band and a
short pulse length characteristic, that is, a characteristic of the frequency characteristic close to a
normal distribution, it is possible to obtain an ultrasonic probe which can realize high resolution
of an ultrasonic image.
[0048]
In the present embodiment, the acoustic impedances of the first and second acoustic matching
layers 2a and 2b are 13 megarails and 4 megarails, respectively. However, the acoustic
impedance of the first acoustic matching layer 2a is described. If the acoustic impedance of the
second acoustic matching layer 2b fluctuates in the range of 3 to 8 megarails, the optimum value
of the acoustic impedance of the third acoustic matching layer 2c is Although calculated,
basically the value of the preferred acoustic impedance of the third acoustic matching layer 2c
does not deviate significantly from the range of 1.9 to 2.3 megarails.
[0049]
In the present embodiment, the configuration in which the piezoelectric elements are onedimensionally arrayed as shown in FIG. 3 has been described. In addition to this, a so-called
electronic scanning array in which a plurality of piezoelectric elements are two-dimensionally
arrayed The same effect can be obtained by applying to an ultrasonic probe of
At this time, even if the three acoustic matching layers are also divided into a plurality in the xaxis direction corresponding to the piezoelectric element, the first and second acoustic matching
layers are not divided and the third acoustic matching layer is not divided. It may be produced by
Further, the same effect can be obtained by applying to an ultrasonic probe of a single
piezoelectric element.
14-04-2019
14
[0050]
In the present embodiment, the case where styrene is used as the resin material has been
described, but the same effect can be obtained by using a styrene-methyl methacrylate
copolymer. The resin material is preferably a synthetic resin, but it is not limited to these resin
materials as long as it is a material that can be mixed with an elastomer material in addition to
the resin material described above.
[0051]
Further, although the case of using butadiene as the elastomer material has been described in
this embodiment, it is not limited thereto as long as it is an elastomer material which can make a
mixture with a resin material even with a natural rubber or a synthetic rubber material. . In
addition, it is more preferable to select an elastomeric material with small ultrasonic attenuation
like butadiene as an elastomeric material. This is because the ultrasonic attenuation of the
material when it is mixed can also be reduced. The ultrasonic attenuation of the acoustic
matching layer affects the sensitivity of the ultrasonic probe, and in the case of an ultrasonic
probe where high sensitivity is desired, it is also necessary to consider the attenuation of the
material of the acoustic matching layer. The acoustic matching layer is preferably made of a
material having a small ultrasonic attenuation, since the influence is particularly large in the case
of an ultrasonic probe used in a high frequency region.
[0052]
In the present embodiment, the case of a mixture of two types of styrene and butadiene has been
described as the third acoustic matching layer 2c, but in addition to the above-mentioned two
types, other materials, for example, strength, may be used. Similar effects can be obtained as long
as the acoustic impedance in the above range can be obtained even if it is necessary to increase
the fibrous material and to increase the hardness by adding powder such as oxide. Be
[0053]
Further, although the case where the acoustic matching layer 2 has three layers has been
described in the present embodiment, the acoustic impedance of the piezoelectric element 1 is
14-04-2019
15
small, for example, a composite ceramic of piezoelectric ceramic and epoxy resin of about 15
megalass. When the following values are used, the acoustic matching layer 2 can be configured
to have a single layer or two layers, and a wide band can be realized.
A layer made of a mixture of a resin material and an elastomeric material may be used for the
one or two acoustic matching layers.
[0054]
Second Embodiment Next, an ultrasound probe according to a second embodiment of the present
invention will be described with reference to the drawings. The second embodiment is a case in
which four acoustic matching layers are provided instead of the acoustic matching layers
provided in the first embodiment. FIG. 5 shows a partial schematic perspective view of the
ultrasound probe 20 according to the second embodiment. The ultrasonic probe 20 has the same
configuration as that of the ultrasonic probe and the acoustic matching layer corresponding to
the first embodiment shown in FIGS. Are given the same reference numerals and explanation
thereof is omitted.
[0055]
The ultrasonic probe 20 includes a plurality of piezoelectric elements 1 arranged, and four layers
disposed on the front surface in the thickness direction corresponding to the respective
piezoelectric elements 1 via the ground electrode 5. The thickness of the acoustic matching layer
202 (202a, 202b, 202c, 202d from the side of the piezoelectric element 1) and the thickness on
the opposite side of the acoustic matching layer 2 (2a, 2b, 2c, 2d) with respect to the
piezoelectric element 1 as necessary. The back load member 3 is disposed on the back side in the
longitudinal direction, and the acoustic lens 4 disposed on the acoustic matching layer 202
(202a, 202b, 202c, 202d) as needed.
[0056]
Further, in the illustrated example, the piezoelectric element 1 and the acoustic matching layer
202 are divided individually, and a material such as silicone rubber or urethane rubber having a
small acoustic coupling in the part of these divided grooves Is filled.
14-04-2019
16
Further, the acoustic lens 4 is provided on the upper surface of the fourth acoustic matching
layer 202d using a material such as silicone rubber as needed.
[0057]
For the first acoustic matching layer 202a, a material having an acoustic impedance in the range
of 15 to 25 mellars, for example, a material such as silicon single crystal, quartz, glass such as
fused quartz, or machinable ceramics is used. For the second acoustic matching layer 202b, a
material having an acoustic impedance in the range of 6 to 12 megarails, for example, graphite
or an epoxy resin in which an epoxy resin is filled with a filler such as a metal or an oxide is used.
In addition, as the third acoustic matching layer 202c, a material having an acoustic impedance
in the range of 3 to 5 megarails, such as graphite, a resin material, or an epoxy resin in which an
epoxy resin is filled with a filler such as a metal or an oxide Use Further, the fourth acoustic
matching layer 202d provided on the object side, that is, the layer of the acoustic matching layer
202 most distant from the piezoelectric element is a mixture of at least two kinds of materials
including an elastomer material, for example, resin Preferably, a material in which an elastomeric
material is mixed is used, and the acoustic impedance preferably has a value in the range of 1.8
to 2.28 megarails. The mixture of the resin material and the elastomer material is made of a
copolymer of the resin material and the elastomer.
[0058]
The acoustic impedance of each acoustic matching layer decreases in order from the layer closer
to the piezoelectric element to the layer closer to the object. The fourth acoustic matching layer
202d is made of a mixture containing an elastomeric material, and thus has high adhesion.
Moreover, since it consists of a mixture of at least 2 types, an acoustic impedance can be suitably
adjusted with the compounding ratio.
[0059]
The reason why the acoustic impedance of the fourth acoustic matching layer 202d is preferably
1.8 to 2.28 megarails will be described using FIG. FIG. 6 is a diagram showing the relationship
between the acoustic impedance of the fourth acoustic matching layer 202d, the fractional band
pulse length, and the frequency ratio band. In FIG. 6, the horizontal axis represents the acoustic
impedance of the fourth acoustic matching layer 202d (in megarails), the vertical axis on the left
14-04-2019
17
is the pulse length (in μs), and the vertical axis on the right is the frequency ratio band
(bandwidth / center It represents the value of frequency) (unit is a percentage).
[0060]
Here, for example, the frequency is set to a center frequency of 7.5 MHz, the acoustic impedance
of the backing material 3 is 7 Mellars, the piezoelectric element 1 is a PZT-based piezoelectric
ceramic, and a PZT-5H equivalent material is used. The third acoustic matching layer 202a is
made of a free-cutting ceramic having an acoustic impedance of 17 Mellars, and the second
acoustic matching layer 202b is formed of an epoxy resin filled with a metallic powder having an
acoustic impedance of 8 Mellars. The layer 202c is made of an epoxy resin filled with metal
powder having an acoustic impedance of 3.8 Mellars, and the acoustic impedance of the fourth
acoustic matching layer 202d located on the object side is in the range of 1.6 to 2.6 Mellars.
Calculated in a varied configuration. The thickness of each acoustic matching layer is 0.27 for the
first acoustic matching layer 202a, and 0.25 for each of the second to fourth acoustic matching
layers 202b, 202c, and 202d. In addition, the relative frequency band of the frequency
characteristic is shown at -6 dB, and the pulse length is shown at -6 dB, -20 dB and -40 dB levels.
The solid line in the figure indicates the frequency ratio band, and the broken line indicates the
pulse length at the level of -6 dB, -20 dB and -40 dB from the bottom, respectively.
[0061]
In FIG. 6, even if the acoustic impedance of the fourth acoustic matching layer 2d changes with a
pulse length of -6 dB, there is almost no large numerical variation, but at -20 dB, the acoustic
impedance becomes smaller than 1.8 Mellars. The value becomes relatively large when the value
becomes larger than 2.3 Megarels, and becomes relatively large when the acoustic impedance
becomes a value smaller than 1.8 Mellars at a level of -40 dB. Since the smaller the pulse length,
the higher the resolution and the better the pulse length, it is important to improve the resolution
that the pulse length be small.
[0062]
On the other hand, with regard to the frequency ratio band in FIG. 6, the larger the value of the
ratio band, the deeper the resolution and the depth of examination. In the case of a four-layer
acoustic matching layer, it is desirable that the fractional band be 90 percent or more. The
14-04-2019
18
acoustic impedance of the fourth acoustic matching layer 202d is greater than or equal to 1.6
Mellars and less than or equal to 2.28 Mellars when the relative band is 90% or more. The
relative band is more preferably 95% or more, and in this case, the acoustic impedance of the
fourth acoustic matching layer 202d is 1.65 Mellars or more and 2.07 Mellars or less.
[0063]
It is desirable that the relative bandwidth be large and the pulse length be short for high
resolution, which means that the shape of the frequency characteristic becomes smooth and
becomes close to the form of a normal distribution, as shown in FIG. It is understood from the
results of both the characteristics and the specific band that the acoustic impedance of the fourth
acoustic matching layer 202d is desirably in the range of not less than 1.8 Mellars and not more
than 2.28 Mellars. Furthermore, it is more preferable that it is 1.8 to 2.07 Mellars.
[0064]
Here, the mixing ratio in the case of using a mixture of styrene which is a resin material and
butadiene which is one of synthetic rubber materials as a material of the fourth acoustic
matching layer 202d is calculated using FIG. When the mixed filling weight ratio of styrene and
butadiene in the range of 1.8 to 2.28 megarails, which is a preferable range of the acoustic
impedance of the fourth acoustic matching layer 202 d, is used for the fourth acoustic matching
layer 202 d The filling weight ratio of butadiene mixed with styrene in the range of 4 to 40%, it is
preferable to mix butadiene with styrene in this range. More preferably, it is in the range of 5 to
40%.
[0065]
A mixture of styrene and butadiene has the advantage that it can be easily made into a film of
any thickness in the same way as filming a resin material, and it can be produced in extremely
large quantities with high precision, and also lowers costs. Can. In addition, since butadiene is
mixed, adhesion is better than styrene alone, and a high quality ultrasonic probe can be obtained.
As can be seen by comparing FIG. 6 and FIG. 3, when comparing the case of the three-layer
acoustic matching layer and the case of the four-layer acoustic matching layer, the ratio band of
the frequency is larger in the four layers, and in the four layers. The relative band has a region of
100% or more, and the frequency band can be broadened as the number of layers of the acoustic
14-04-2019
19
matching layer increases, and the characteristic tends to be a desirable characteristic for high
resolution.
[0066]
As described above, in the configuration in which the four acoustic matching layers 202 are
provided, a mixture of styrene and butadiene in any mixing ratio is used as the fourth acoustic
matching layer 202 d provided on the object side. Since it is possible to obtain a wide band and a
short pulse length characteristic, that is, a characteristic of the frequency characteristic close to a
normal distribution, it is possible to obtain an ultrasonic probe which can realize high resolution
of an ultrasonic image.
[0067]
In the present embodiment, the acoustic impedances of the first acoustic matching layer 202a,
the second acoustic matching layer 202b, and the third acoustic matching layer 202c are 17
megalars, 8 megalars, and 3.8 megarails, respectively. The acoustic impedance of the first
acoustic matching layer 202a is 15 to 25 Mellars, the acoustic impedance of the second acoustic
matching layer 202b is 6 to 12 Mellars, and the acoustic impedance of the third acoustic
matching layer 202c is 3 to In the case of variation in the range of 5 M Rails, the optimum value
of the acoustic impedance of the fourth acoustic matching layer 202d is calculated in each
combination, but basically the preferred acoustic of the fourth acoustic matching layer 202d Is
the impedance value 1.8? Not materially departing from the scope of 2.28 MRayls.
[0068]
In the present embodiment, the configuration in which the piezoelectric elements are arranged in
one dimension as shown in FIG. 5 is described, but in addition to that, a so-called electronic
scanning array in which a plurality of elements are arranged in two dimensions in the x-axis
direction The same effect can be obtained by applying to an ultrasonic probe of
At this time, even if the four acoustic matching layers are divided into a plurality in the x-axis
direction corresponding to the piezoelectric element, the first, second, and third acoustic
matching layers are divided to form the fourth acoustic matching layer. May be produced without
division.
Further, the same effect can be obtained by applying to an ultrasonic probe of a single
14-04-2019
20
piezoelectric element.
[0069]
In the present embodiment, the case where styrene is used as the resin material has been
described, but the same effect can be obtained by using a styrene-methyl methacrylate
copolymer. The resin material is preferably a synthetic resin, but it is not limited to these resin
materials as long as it is a material that can be mixed with an elastomer material in addition to
the resin material described above.
[0070]
Further, although the case of using butadiene as the elastomer material has been described in
this embodiment, it is not limited thereto as long as it is an elastomer material which can make a
mixture with a resin material even with a natural rubber or a synthetic rubber material. . In
addition, it is more preferable to select an elastomeric material with small ultrasonic attenuation
like butadiene as an elastomeric material. This is because the ultrasonic attenuation of the
material when it is mixed can also be reduced. The ultrasonic attenuation of the acoustic
matching layer affects the sensitivity of the ultrasonic probe, and in the case of an ultrasonic
probe where high sensitivity is desired, it is also necessary to consider the attenuation of the
material of the acoustic matching layer. The acoustic matching layer is preferably made of a
material having a small ultrasonic attenuation, since the influence is particularly large in the case
of an ultrasonic probe used in a high frequency region.
[0071]
In the present embodiment, the case of a mixture of two types of styrene and butadiene has been
described as the fourth acoustic matching layer 202d, but in addition to the above two types,
other materials, for example, strength, may be used there. Similar effects can be obtained as long
as the acoustic impedance in the above range can be obtained even if it is necessary to increase
the fibrous material and to increase the hardness by adding powder such as oxide. Be
[0072]
Third Embodiment Next, an ultrasound probe according to a third embodiment of the present
14-04-2019
21
invention will be described with reference to the drawings.
The third embodiment is a case where five acoustic matching layers are provided instead of the
acoustic matching layer provided in the first embodiment. FIG. 7 shows a partial schematic
perspective view of the ultrasound probe 30 according to the second embodiment. The ultrasonic
probe 30 has the same configuration as the ultrasonic probe and the acoustic matching layer
corresponding to the first embodiment shown in FIG. The code is attached and the description is
omitted.
[0073]
The ultrasonic probe 30 comprises a plurality of piezoelectric elements 1 arranged, and five
layers of acoustic waves disposed on the front surface in the thickness direction corresponding to
the respective piezoelectric elements 1 via the ground electrode 5. Matching layer 302 (302a,
302b, 302c, 302d, 302e from the side of the piezoelectric element 1) and, if necessary, the
opposite of the acoustic matching layer 302 (302a, 302b, 302c, 302d, 302e) to the piezoelectric
element 1 The back load material 3 is disposed on the back side in the thickness direction, and
the acoustic lens 4 is disposed on the acoustic matching layer 302 (302a, 302b, 302c, 302d,
302e) as needed.
[0074]
Further, in the illustrated example, the piezoelectric element 1 and the acoustic matching layer
302 are divided individually, and a material such as silicone rubber or urethane rubber having a
small acoustic coupling in the part of the divided grooves Is filled.
Further, on the upper surface of the fifth acoustic matching layer 302e, the acoustic lens 4 is
provided using a material such as silicone rubber as needed.
[0075]
For the first acoustic matching layer 302a, a material having an acoustic impedance in the range
of 15 to 25 mellars, for example, a material such as silicon single crystal, quartz, glass such as
fused quartz, or machinable ceramics is used. As the second acoustic matching layer 302b, a
material having an acoustic impedance in the range of 8 to 14 megarails, for example, graphite
14-04-2019
22
filled with metal or oxide, or epoxy resin filled with filler such as metal or oxide Use epoxy resin
etc. In addition, as the third acoustic matching layer 302c, a material having an acoustic
impedance in the range of 3 to 6 megarails, such as graphite, a resin material, or an epoxy resin
in which an epoxy resin is filled with a filler such as a metal or an oxide Use As the fourth
acoustic matching layer 302d, a material having an acoustic impedance in the range of 2 to 3
megarails, for example, a resin material or a material obtained by mixing an elastomer material
with a resin material is used. Further, the fifth acoustic matching layer 302e provided on the
object side, that is, the layer of the acoustic matching layer 302 most distant from the
piezoelectric element is a mixture of at least two kinds of materials including an elastomer
material, for example, resin Preferably, a material in which an elastomeric material is mixed is
used, and the acoustic impedance preferably has a value in the range of 1.6 to 1.8 Mellars. The
mixture of the resin material and the elastomer material is made of a copolymer of the resin
material and the elastomer.
[0076]
The acoustic impedance of each acoustic matching layer decreases in order from the layer closer
to the piezoelectric element to the layer closer to the object.
[0077]
The fifth acoustic matching layer 302e is made of a mixture containing an elastomeric material,
and thus has high adhesion.
Moreover, since it consists of a mixture of at least 2 types, an acoustic impedance can be suitably
adjusted with the compounding ratio.
[0078]
The reason why the acoustic impedance of the fifth acoustic matching layer 302e is preferably
1.6 to 1.8 Mellars will be described with reference to FIG. FIG. 8 is a diagram showing the
relationship between the acoustic impedance of the fifth acoustic matching layer 302e, the
fractional band pulse length, and the frequency ratio band. In FIG. 8, the horizontal axis
represents the acoustic impedance of the fifth acoustic matching layer 2e (in megarails), the
vertical axis on the left is the pulse length (in μs), and the vertical axis on the right is the
frequency ratio band (bandwidth / center It represents the value of frequency) (unit is a
14-04-2019
23
percentage).
[0079]
Here, for example, the frequency is set to a center frequency of 7.5 MHz, the acoustic impedance
of the backing material 3 is 7 Mellars, the piezoelectric element 1 is a PZT-based piezoelectric
ceramic, and a PZT-5H equivalent material is used. The third acoustic matching layer 302a is
made of a free-cutting ceramic having an acoustic impedance of 23 mellars, and the second
acoustic matching layer 302b is formed of a metal powder-filled epoxy resin having an acoustic
impedance of 10 mellars. The matching layer 302c is a metal powder-filled epoxy resin with an
acoustic impedance of 4.4 Mellars, and the fourth acoustic matching layer 302d is a material
with an acoustic impedance of 2.3 Mellars, a resin material mixed with an elastomer material The
fifth acoustic matching located on the subject side using The acoustic impedance of 302e was
calculated in the structure is varied in a range of 2.3 MRayls 1.5. The thickness of each acoustic
matching layer was 0.28 wavelength for the first acoustic matching layer 302a, and 0.25
wavelength for each of the second to fifth acoustic matching layers 302b, 302c, 302d, and 302e.
In addition, the relative frequency band of the frequency characteristic is shown at -6 dB, and the
pulse length is shown at -6 dB, -20 dB and -40 dB levels. The solid line in the figure indicates the
frequency ratio band, and the broken line indicates the pulse length at the level of -6 dB, -20 dB
and -40 dB from the bottom, respectively.
[0080]
In FIG. 8, even if the acoustic impedance of the fifth acoustic matching layer 302e changes with a
pulse length of -6 dB, there is almost no large numerical variation, but at -20 dB, the acoustic
impedance becomes a value larger than 1.8 Mellars When the value is relatively large, at a level
of -40 dB, the value becomes relatively large when the acoustic impedance becomes smaller than
1.6 Mellars and larger than 1.9 Mellars. Since the smaller the pulse length, the higher the
resolution and the better the pulse length, it is important to improve the resolution that the pulse
length be small.
[0081]
On the other hand, regarding the frequency ratio band in FIG. 8, the larger the value of the ratio
band, the deeper the resolution and the depth of examination. In the case of a five-layer acoustic
14-04-2019
24
matching layer, it is desirable that the relative bandwidth be 100 percent or more. The specific
impedance is 100% or more when the acoustic impedance of the fifth acoustic matching layer
302e is 2.07 Mellars or less.
[0082]
It is desirable that the relative bandwidth be large and the pulse length be short for high
resolution, which means that the shape of the frequency characteristic becomes smooth and
becomes close to the shape of a normal distribution, as shown in FIG. It is understood from the
results of both the characteristics and the specific band that the acoustic impedance of the fifth
acoustic matching layer 302e is desirably in the range of not less than 1.6 Mellars and not more
than 1.8 Mellars. Furthermore, the acoustic impedance of the fifth acoustic matching layer 302e
is more preferably in the range of not less than 1.7 Mellars and not more than 1.8 Mellars.
[0083]
Here, the mixing ratio in the case of using a mixture of styrene, which is a resin material, and
butadiene, which is one of synthetic rubber materials, as the material of the fifth acoustic
matching layer 302e is calculated using FIG. When the mixed filling weight ratio of styrene and
butadiene is in the range of 1.6 to 1.8 megarails which is a preferable range of the acoustic
impedance of the fifth acoustic matching layer 302e, it is used in the fifth acoustic matching
layer 302e The ratio by weight of butadiene mixed with styrene is in the range of 40 to 68%, and
it is preferable to mix butadiene with styrene in this range. Furthermore, it is more preferable if it
is in the range of 40 to 55%.
[0084]
A mixture of styrene and butadiene has the advantage that it can be easily made into a film of
any thickness in the same way as filming a resin material, and it can be produced in extremely
large quantities with high precision, and also lowers costs. Can. In addition, since butadiene is
mixed, adhesion is better than styrene alone, and a high quality ultrasonic probe can be obtained.
[0085]
14-04-2019
25
As can be seen by comparing FIG. 8 and FIG. 6, when comparing the case of the four acoustic
matching layers and the case of the five acoustic matching layers, the ratio band of the frequency
is larger in the five layers, and in the five layers. It is possible to obtain an area with a relative
bandwidth of 100% or more in a wide range, broaden the frequency band as the number of
acoustic matching layers increases, and become a desirable characteristic for high resolution. It is
in.
[0086]
As described above, in the configuration in which the five acoustic matching layers 302 are
provided, a mixture of styrene and butadiene in any mixing ratio is used as the fifth acoustic
matching layer 302 e provided on the object side. Since it is possible to obtain a wide band and a
short pulse length characteristic, that is, a characteristic of the frequency characteristic close to a
normal distribution, it is possible to obtain an ultrasonic probe which can realize high resolution
of an ultrasonic image.
[0087]
In the present embodiment, the acoustic impedances of the first acoustic matching layer 302a,
the second acoustic matching layer 302b, the third acoustic matching layer 302c, and the fourth
acoustic matching layer 302d are 23 megarails and 10 megarails, respectively. The description is
given for the case of 4.4 Mellars and 2.3 Mellars, but the acoustic impedance of the first acoustic
matching layer 302a is 15 to 25, the acoustic impedance of the second acoustic matching layer
302b is 8 to 14 Mellars, When the acoustic impedance of the third acoustic matching layer 302c
varies in the range of 3 to 6 megarails and the acoustic impedance of the fourth acoustic
matching layer 302d varies in the range of 2 to 3, the fifth acoustic matching layer 302e in each
combination. Of the acoustic impedance of Although such values are calculated, basically it does
not deviate significantly from the preferred acoustic impedance values ranging from 1.6 to 1.8
MRayls fifth acoustic matching layer 302 e.
[0088]
In the present embodiment, the configuration in which the piezoelectric elements are arranged in
one dimension as shown in FIG. 7 has been described, but in addition to that, a so-called
electronic scanning array in which a plurality of piezoelectric elements are arranged in two
dimensions The same effect can be obtained by applying to an ultrasonic probe of
At this time, even if the five acoustic matching layers are divided into a plurality in the x-axis
14-04-2019
26
direction in correspondence with the piezoelectric element, the first, second, third, and fourth
acoustic matching layers are divided to form a fifth The acoustic matching layer may be
produced without being divided.
Further, the same effect can be obtained by applying to an ultrasonic probe of a single
piezoelectric element.
[0089]
In the present embodiment, the case where styrene is used as the resin material has been
described, but the same effect can be obtained by using a styrene-methyl methacrylate
copolymer.
The resin material is preferably a synthetic resin, but it is not limited to these resin materials as
long as it is a material that can be mixed with an elastomer material in addition to the resin
material described above.
[0090]
Further, although the case of using butadiene as the elastomer material has been described in
this embodiment, it is not limited thereto as long as it is an elastomer material which can make a
mixture with a resin material even with a natural rubber or a synthetic rubber material. . In
addition, it is more preferable to select an elastomeric material with small ultrasonic attenuation
like butadiene as an elastomeric material. This is because the ultrasonic attenuation of the
material when it is mixed can also be reduced. The ultrasonic attenuation of the acoustic
matching layer affects the sensitivity of the ultrasonic probe, and in the case of an ultrasonic
probe where high sensitivity is desired, it is also necessary to consider the attenuation of the
material of the acoustic matching layer. The acoustic matching layer is preferably made of a
material having a small ultrasonic attenuation, since the influence is particularly large in the case
of an ultrasonic probe used in a high frequency region.
[0091]
In the present embodiment, the case of a mixture of two types of styrene and butadiene has been
described as the fifth acoustic matching layer 302e, but in addition to the above two types, other
14-04-2019
27
materials, for example, strength, may be used there. Similar effects can be obtained as long as the
acoustic impedance in the above range can be obtained even if it is necessary to increase the
fibrous material and to increase the hardness by adding powder such as oxide. Be
[0092]
Also, according to the first embodiment, the second embodiment, and the third embodiment, as
the number of acoustic matching layers increases, the acoustic impedance of the acoustic
matching layer provided on the subject side is 1. of the acoustic impedance of the subject. It can
be seen that the value is approaching 54 megarails.
[0093]
Fourth Embodiment Next, an ultrasound probe according to a fourth embodiment of the present
invention will be described with reference to the drawings.
The fourth embodiment differs from the second embodiment in that the conductor foil 8
electrically connected to the ground electrode 5 is provided.
FIG. 9 shows a partial schematic perspective view of the ultrasound probe 40 according to the
fourth embodiment. The ultrasonic probe 40 has the same configuration as that of the ultrasonic
probe and the conductor foil 8 corresponding to the second embodiment shown in FIG. The code
is attached and the description is omitted.
[0094]
A conductor foil 8 is formed on the surface of the ground electrode 5 provided on one surface of
the piezoelectric element 1 and these are electrically connected. Further, an acoustic matching
layer 202 (202a, 202b, 202c, 202d from the side of the piezoelectric element 1) is provided on
the surface of the conductor foil 8. Signal electric terminals 7 provided on the surface of the
backing material 3, piezoelectric elements 1, conductor foils 8, acoustic matching layers 2 (202
a, 202 b, 202 c, 202 d) are bonded together with an adhesive such as epoxy resin and laminated
You may
14-04-2019
28
[0095]
A portion of the back load member 3 and the signal electric terminal 7, the piezoelectric element
1, the conductor foil 8, and the acoustic matching layer 202 (202a, 202b, 202c, 202d) are
divided into plural pieces by a dicing saw or the like, as shown in FIG. To form an array. The
divided grooves may be filled with silicone rubber, urethane resin or the like, and the acoustic
lens 4 may be provided thereon if necessary.
[0096]
Although it is preferable to use metals, such as copper foil and aluminum foil, as the conductor
foil 8, if it is a conductor, it is not limited to these materials. When copper foil is used as the
conductor foil 8, the acoustic impedance of copper is approximately 44.6 megarails, which is
larger than the acoustic impedance of the piezoelectric element 1 and the first acoustic matching
layer 202a, and thus acoustically mismatched. Since the thickness of the copper foil is preferably
as thin as possible because it affects frequency characteristics and sensitivity, it is preferable that
the thickness be less than about 1/40 of the wavelength. When aluminum foil is used as the
conductor foil 8, the acoustic impedance is approximately 17 megarails, which is a value close to
the first acoustic matching layer 202 a, so the aluminum foil functions as a part of the first
acoustic matching layer It can be done. However, it is difficult to process and divide the
aluminum foil itself as the first acoustic matching layer by using a dicing saw or the like, so it is
desirable to use the conductor foil 8 with a thickness equal to or less than the processable
division thickness. .
[0097]
The conductor foil 8 can be easily wired by soldering or the like by making the conductor foil 8
larger than the piezoelectric element 1 and the acoustic matching layer 202 and extending it.
[0098]
As described above, the conductor terminal 8 for signal is provided by providing the conductor
foil 8 on the upper surface of the piezoelectric element 1 without the intervention of the acoustic
matching layer and making all the acoustic matching layers laminated above the conductor foil 8.
Since the piezoelectric element 1 can transmit and receive ultrasonic waves by applying a voltage
to the conductive foil 8 and the conductor foil 8, the acoustic matching layer does not need to
14-04-2019
29
consider the electrical connection at all, so that each layer is specialized for the acoustic point of
view. There is a great advantage that it is possible to freely select the material compatible with.
That is, since the material of the acoustic matching layer 202 (202a, 202b, 202c, 202d) may be
any material of a conductor, a semiconductor, and an insulator, the range of selection is
broadened.
[0099]
That is, according to the present embodiment, when selecting the material of each acoustic
matching layer satisfying the acoustic impedance as described in the second embodiment, it is
not necessary to pay attention to the conductivity of the material. For the first acoustic matching
layer 202a, a material having an acoustic impedance in the range of 15 to 25 megarails, for
example, a material such as silicon single crystal, quartz, glass such as fused quartz, or
machinable ceramics is used. Also, as the second acoustic matching layer 202b, a material having
an acoustic impedance in the range of 6 to 12 megarails, such as graphite or an epoxy resin in
which an epoxy resin is filled with a filler such as a metal or an oxide is used. . In addition, as the
third acoustic matching layer 202c, a material having an acoustic impedance in the range of 3 to
5 megarails, for example, a graphite, a resin material, or an epoxy resin in which an epoxy resin
is filled with a filler such as metal or oxide Use. The fourth acoustic matching layer 202d
provided on the subject side is a mixture of at least two types of materials including an elastomer
material, for example, a material obtained by mixing an elastomer material with a resin material,
and the acoustic impedance is from 1.8 to It is preferred to have a value in the range of 2.28
megarails.
[0100]
In the present embodiment, although the case where four acoustic matching layers are provided
has been described, the same effect can be obtained even when three or five or more acoustic
matching layers are provided.
[0101]
INDUSTRIAL APPLICABILITY The ultrasonic probe according to the present invention can be
used in various medical fields where ultrasonic diagnosis of a subject such as a human body is
performed, and further in an industrial field aiming at internal flaw detection of materials and
structures.
14-04-2019
30
[0102]
DESCRIPTION OF SYMBOLS 1 piezoelectric element 2 acoustic matching layer 2a 1st acoustic
matching layer 2b 2nd acoustic matching layer 2c 3rd acoustic matching layer 3 back load
material 4 acoustic lens 5 grounding electrode 6 signal electrode 7 signal electrical terminal 8
conductor foil 10 Ultrasonic probe 11 Piezoelectric element 12 Acoustic matching layer 13
Acoustic lens 14 Back load material 20 Ultrasonic probe 30 Ultrasonic probe 40 Ultrasonic probe
100 Ultrasonic probe 202 Acoustic matching layer 202a 1st Acoustic matching layer 202b
second acoustic matching layer 202c third acoustic matching layer 202d fourth acoustic
matching layer 302a first acoustic matching layer 302b second acoustic matching layer 302c
third acoustic matching layer 302d fourth Acoustic matching layer 302 e fifth acoustic matching
layer
14-04-2019
31
Документ
Категория
Без категории
Просмотров
0
Размер файла
49 Кб
Теги
description, jp2015188121
1/--страниц
Пожаловаться на содержимое документа