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DESCRIPTION JP2013176537

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DESCRIPTION JP2013176537
An object of the present invention is to improve the conversion efficiency and S / N of received
signals in a plurality of organic piezoelectric elements while having excellent acoustic
transmittance to ultrasonic beams transmitted from a plurality of inorganic piezoelectric
elements. Provided is an ultrasonic probe capable of accurately aligning the arrangement
positions of a plurality of inorganic piezoelectric elements and a plurality of organic piezoelectric
elements, and further maintaining high characteristics of the organic piezoelectric element even
after completion of the device. A backing material 1, an inorganic piezoelectric element layer
91a, an acoustic matching layer 94, an organic layer 95, and a conductive layer 96 are
sequentially laminated, and dicing is performed from the conductive layer 96 to the inorganic
piezoelectric element layer 91a at an arbitrary pitch in the lamination direction. Thus, the
fragments of the plurality of inorganic piezoelectric elements 2, the first acoustic matching layer
3, the lower organic layer 42, and the signal electrode layer 44 are formed sequentially in
alignment and formed one on top of the other on the signal electrode layer 44. The organic layer
41 and the ground electrode layer 43 are overlapped and joined to form a plurality of organic
piezoelectric elements 5 composed of the signal electrode layer 44, the upper organic layer 41
and the ground electrode layer 43. [Selected figure] Figure 1
Ultrasonic probe and method of manufacturing the same
[0001]
The present invention relates to an ultrasonic probe and a method of manufacturing the same,
and more particularly to an ultrasonic probe in which a plurality of inorganic piezoelectric
elements and a plurality of organic piezoelectric elements are stacked on one another and a
method of manufacturing the same.
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1
[0002]
Heretofore, in the medical field, ultrasonic diagnostic apparatuses using ultrasonic images have
been put to practical use.
In general, this type of ultrasonic diagnostic apparatus transmits an ultrasonic beam from an
ultrasonic probe toward the inside of a subject, receives an ultrasonic echo from the subject by
the ultrasonic probe, and receives the ultrasonic echo from the subject. The electrical processing
of the signal produces an ultrasound image.
[0003]
In recent years, in order to perform more accurate diagnosis, harmonic imaging that receives and
visualizes harmonic components generated by distortion of an ultrasonic waveform due to nonlinearity of an object has become mainstream. In recent years, as a new diagnostic method using
ultrasound, photoacoustic imaging, which irradiates a laser to a living body and receives and
visualizes weak, wide-band elastic waves generated by adiabatic expansion, is in the spotlight . As
an ultrasonic probe suitable for this harmonic imaging or photoacoustic imaging, for example, as
disclosed in Patent Document 1, an inorganic piezoelectric material such as lead zirconate
titanate (Pb (Zr, Ti) O 3) is used. It has been proposed that a plurality of used inorganic
piezoelectric elements and a plurality of organic piezoelectric elements using an organic
piezoelectric such as polyvinylidene fluoride (PVDF) are laminated. A high power ultrasonic beam
can be transmitted by the inorganic piezoelectric element, and a harmonic signal can be received
with high sensitivity by the organic piezoelectric element. Moreover, while receiving the
reception signal of a normal ultrasonic wave by an inorganic piezoelectric element, the
broadband signal of photoacoustic imaging can be received with high sensitivity by an organic
piezoelectric element.
[0004]
International Publication No. 2008/010509
[0005]
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Here, since the ultrasonic beams output from the plurality of inorganic piezoelectric elements are
transmitted from the ultrasonic probe into the subject after being transmitted through the
organic piezoelectric body, the thickness of the organic piezoelectric body is the ultrasonic wave.
It is designed to increase the sound transmission of the beam.
Specifically, the organic piezoelectric body is designed in the vicinity of a thickness satisfying the
λ / 4 resonance condition with respect to the wavelength λ of the fundamental wave
transmitted from the plurality of inorganic piezoelectric elements. For this reason, the thickness
of the organic piezoelectric material can not be freely designed, and in order to satisfy the abovementioned resonance condition, it has been necessary to design the organic piezoelectric
material with a certain thickness. On the other hand, since the organic piezoelectric material has
a small relative dielectric constant, when the organic piezoelectric device is formed thick, the
electric capacity is reduced, and the reception signal generated by the ultrasonic wave received
by the organic piezoelectric device is efficiently obtained on the circuit. It was difficult. In
addition, since the thermal noise increases when the electric capacity is small, the S / N with the
acquired signal tends to be disadvantageous. Moreover, when laminating | stacking an organic
piezoelectric material on an inorganic piezoelectric element, if mutual electrode positions do not
correspond with respect to a beam transmission direction, a focus shift and the fall of receiving
efficiency will be caused. Therefore, it is desirable that the electrode positions of the inorganic
piezoelectric element and the laminated organic piezoelectric element be as close as possible to
the beam transmission direction, but it is difficult to make them exactly in the conventional
configuration and manufacturing method. The Furthermore, since the degree of crystallization of
the organic piezoelectric material gradually decreases as the temperature rises, the upper limit
temperature for use is at a temperature considerably lower than the Curie point. For example, the
upper limit temperature of use of typical polyvinylidene fluoride (PVDF) is 80.degree. C., and that
of polyvinylidene fluoride trifluoride ethylene copolymer (P (VDF-TrFE)) is 100.degree.
Therefore, during the process, the ferroelectricity deteriorates and depolarization occurs if the
temperature is higher than this temperature. Repolarization is an effective means as a
ferroelectric deterioration recovery means, but the coercive electric field (Ec) of the organic
piezoelectric material is extremely large, about 400 kV / cm to 450 kV / cm. Therefore, it is
necessary to apply a very high voltage to repolarize the once depolarized organic piezoelectric
material on the device, which is difficult in the process. From the above, when laminating an
organic piezoelectric material on an inorganic piezoelectric material, it is necessary to make it as
low temperature process as possible, with a small number of heat histories, but with the
conventional configuration and manufacturing method, it is difficult to apply the heat history
hardly Met.
[0006]
The present invention has been made to solve such conventional problems, and provides a
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plurality of organic piezoelectrics while having an excellent acoustic transmittance for ultrasonic
beams transmitted from a plurality of inorganic piezoelectric elements. The conversion efficiency
and S / N of the reception signal in the element are improved, and the position of the electrode of
the inorganic piezoelectric element that transmits and receives ultrasonic waves exactly matches
the position of the beam transmission direction of the organic piezoelectric element dedicated to
ultrasonic reception. It is an object of the present invention to provide an ultrasonic probe
capable of maintaining high characteristics of an organic piezoelectric element even after
completion of the device, and a method of manufacturing the same.
[0007]
An ultrasonic probe according to the present invention includes a backing material, a plurality of
inorganic piezoelectric elements arranged on the surface of the backing material, and a first
acoustic matching layer arranged on the plurality of inorganic piezoelectric elements. And a
second acoustic matching layer disposed on the first acoustic matching layer, wherein the second
acoustic matching layer includes an upper organic layer constituting a plurality of organic
piezoelectric elements, and the upper organic layer. And a lower organic layer for acoustic
matching to the plurality of inorganic piezoelectric elements in combination with the layer.
[0008]
Here, the upper organic layer is preferably thinner than the lower organic layer.
Further, the plurality of organic piezoelectric elements may include a sheet-like upper organic
layer, a ground electrode layer extending over the surface of the upper organic layer, and a back
surface of the upper organic layer facing the lower organic layer. And a plurality of signal
electrode layers arranged in parallel to each other in parallel in the stacking direction so as to
separate each layer from the plurality of signal electrode layers to the plurality of inorganic
piezoelectric elements into a plurality of pieces It is preferable that the plurality of organic
piezoelectric elements and the plurality of inorganic piezoelectric elements be arranged at the
same pitch, by further including a plurality of separation parts extending in the direction of.
[0009]
Further, each of the fragments constituting the plurality of inorganic piezoelectric elements, or
each fragment constituting each of the plurality of inorganic piezoelectric elements and the first
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acoustic matching layer, or the plurality of inorganic piezoelectric elements and the first A subdie forming groove extending in the stacking direction may be provided to further separate each
of the pieces constituting the acoustic matching layer and the lower organic layer of the second
acoustic matching layer into a plurality of sub dies.
Further, the plurality of organic piezoelectric elements are used as a receiving device for
receiving the ultrasonic waves transmitted from the plurality of inorganic piezoelectric elements,
and the upper organic layer is efficient on the circuit with the received ultrasonic echoes as
reception signals. In order to obtain well and improve the S / N, it is formed with a thickness
having a predetermined electric capacity, and the sum of the thickness of the upper organic layer
and the thickness of the lower organic layer is the plurality of inorganic materials. It is preferable
to form the value so as to obtain the desired acoustic matching for the ultrasonic wave
transmitted from the piezoelectric element.
[0010]
The upper organic layer and the lower organic layer preferably have an acoustic impedance
within ± 10% of each other. Preferably, the lower organic layer has a larger acoustic impedance
than the upper organic layer and a smaller acoustic impedance than the first acoustic matching
layer. The plurality of inorganic piezoelectric elements may include a plurality of inorganic
piezoelectrics separated from each other, a plurality of signal electrode layers and a plurality of
ground electrode layers respectively disposed on both sides of the plurality of inorganic
piezoelectrics. preferable.
[0011]
Further, the plurality of inorganic piezoelectric materials can be composed of a Pb-based
perovskite oxide such as lead zirconate titanate (Pb (Zr, Ti) O3) or a magnesium niobate / lead
titanate solid solution (PMN-PT). . Further, the upper organic layer can be composed of only an
organic material, and the lower organic layer can be composed of an organic material or a
composite material of an organic material and an inorganic material. Furthermore, the upper
organic layer and the lower organic layer may be composed of a vinylidene fluoride compound
such as polyvinylidene fluoride (PVDF) or polyvinylidene fluoride trifluoride ethylene copolymer
(P (VDF-TrFE)). it can. In addition, an acoustic lens may be further provided on the plurality of
organic piezoelectric elements. In addition, a protective layer may be further provided between
the plurality of organic piezoelectric elements and the acoustic lens to protect the plurality of
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organic piezoelectric elements.
[0012]
In addition, an amplifier for an organic piezoelectric element directly connected to the plurality
of organic piezoelectric elements can be further included. Further, the device further includes a
light irradiation unit that irradiates irradiation light toward the subject, and ultrasonic waves
induced from the subject by the irradiation light being irradiated from the light irradiation unit
may be the plurality of organic piezoelectric elements or the above A plurality of inorganic
piezoelectric elements can receive signals.
[0013]
In the method of manufacturing an ultrasonic probe according to the present invention, the
inorganic piezoelectric element layer extending over the backing material is bonded onto the
surface of the backing material, and the inorganic piezoelectric element layer is stretched over
the inorganic piezoelectric element layer. An existing acoustic matching layer is joined, an
organic layer extending over the acoustic matching layer is joined on the acoustic matching layer,
and a conductive layer is formed on the entire surface of the organic layer; A plurality of
inorganic piezoelectric elements are arrayed by dicing at an arbitrary pitch in the stacking
direction up to the element layer, and the first acoustic matching layer, the lower organic layer,
and the signal electrode layer on the plurality of inorganic piezoelectric elements The signal is
formed by aligning the fragments in a batch, and bonding the upper organic layer extending over
the signal electrode layer over the signal electrode layer after the ground electrode layer is
formed over the entire surface. Electrode layer, in which are arranged forming an organic
piezoelectric element (sheet) made up of the upper organic layer and the ground electrode layer.
[0014]
Here, the upper organic layer and the lower organic layer constitute a second acoustic matching
layer, and the sum of the thickness of the upper organic layer and the thickness of the lower
organic layer can be obtained from the plurality of inorganic piezoelectric elements It is
preferable to form in the vicinity of a value satisfying the λ / 4 resonance condition with respect
to the wavelength λ of the fundamental wave to be transmitted.
[0015]
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According to the present invention, the second acoustic matching layer includes the upper
organic layer constituting the plurality of organic piezoelectric elements, and the lower organic
layer for performing acoustic matching on the plurality of inorganic piezoelectric elements in
combination with the upper organic layer The present invention improves the acquisition
efficiency of reception signals generated by a plurality of organic piezoelectric elements while
having excellent acoustic transmittance to ultrasonic beams transmitted from a plurality of
inorganic piezoelectric elements, and It becomes possible to improve S / N.
In addition, the position of the electrode of the inorganic piezoelectric element that transmits and
receives ultrasonic waves exactly matches the position of the beam transmitting direction of the
organic piezoelectric element dedicated to ultrasonic reception, and the characteristics of the
organic piezoelectric element are maintained high even after device completion. Is also possible.
[0016]
FIG. 1 is a partial perspective view showing an ultrasound probe according to an embodiment of
the present invention.
It is a sectional view showing the composition of the ultrasound probe concerning an
embodiment. It is sectional drawing which shows the manufacturing method of the ultrasound
probe which concerns on embodiment to process order. It is sectional drawing which shows the
structure of the ultrasound probe which concerns on a modification. It is a figure which shows
the structure of the ultrasound probe which concerns on another modification.
[0017]
Hereinafter, an embodiment of the present invention will be described based on the attached
drawings. FIGS. 1 and 2 show the configuration of an ultrasonic probe according to an
embodiment of the present invention. A plurality of inorganic piezoelectric elements 2 are
arrayed at a pitch P on the surface of the backing material 1. The plurality of inorganic
piezoelectric elements 2 have a plurality of inorganic piezoelectric members 21 separated from
one another, the signal electrode layer 22 is joined to one surface of each inorganic piezoelectric
member 21, and the ground electrode layer 23 is formed on the other surface. It is joined. That
is, each inorganic piezoelectric element 2 is formed of a dedicated inorganic piezoelectric body
21, a signal electrode layer 22 and a ground electrode layer 23. The first acoustic matching layer
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3 is bonded onto such a plurality of inorganic piezoelectric elements 2. The first acoustic
matching layer 3 is divided into a plurality of pieces and arranged at the same pitch P as the
plurality of inorganic piezoelectric elements 2.
[0018]
In addition, it is preferable to separate and form each piece which comprises several inorganic
piezoelectric element 2 into several sub dice | dies. For example, each fragment constituting each
layer of a plurality of inorganic piezoelectric bodies 21, signal electrode layer 22 and ground
electrode layer 23 (a plurality of inorganic piezoelectric elements 2), or a plurality of inorganic
piezoelectric bodies 21, signal electrode layer 22, a ground electrode A sub-die forming groove
extending in the stacking direction can be formed to further separate each of the pieces
constituting the layer 23 and the first acoustic matching layer 3 into a plurality of pieces. In
addition, the lamination direction is such that the fragments constituting the plurality of
inorganic piezoelectric bodies 21, the signal electrode layer 22, the ground electrode layer 23,
the first acoustic matching layer 3 and the lower organic layer 42 are further separated into a
plurality of fragments. It is also possible to form a sub-die forming groove extending towards the.
At this time, it is preferable to form one or two sub-die forming grooves for each inorganic
piezoelectric element 2 to form two or three sub-dies. As described above, by forming the
plurality of sub dice, the piezoelectric multipliers of the plurality of inorganic piezoelectric
elements 2 can be improved, and the transmission / reception sensitivity of the ultrasonic probe
can be improved.
[0019]
The second acoustic matching layer 4 is bonded onto the first acoustic matching layer 3. The
second acoustic matching layer 4 has two layers of an upper organic layer 41 and a lower
organic layer 42. The lower organic layer 42 is divided into a plurality of pieces and arranged on
the first acoustic matching layer 3 at the same pitch P as the plurality of inorganic piezoelectric
elements 2. On the other hand, the upper organic layer 41 has a sheet-like shape and extends
over the entire lower organic layer 42 without being divided into a plurality of pieces. The sum of
the thickness of the upper organic layer 41 and the thickness of the lower organic layer 42 is set
to such a value that the desired acoustic matching is performed with respect to the ultrasonic
waves transmitted from the plurality of inorganic piezoelectric elements. For example, the sum of
the thickness of the upper organic layer 41 and the thickness of the lower organic layer 42 is the
fundamental wave of an ultrasonic wave transmitted from the plurality of inorganic piezoelectric
elements 2 (center frequency of -6 dB band of maximum sensitivity of inorganic piezoelectric 21)
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And the second organic matching layer 4 in which the upper organic layer 41 and the lower
organic layer 42 are combined is formed to be close to a thickness satisfying the λ / 4
resonance condition with respect to the wavelength λ of It is possible to have an excellent
acoustic transmittance for ultrasonic waves transmitted from the inorganic piezoelectric element.
[0020]
Furthermore, the upper organic layer 41 constitutes a plurality of organic piezoelectric elements
5. That is, a ground electrode layer 43 extending over the surface is joined to the upper organic
layer 41, and separated on the back surface opposite to the lower organic layer 42 at the same
pitch P as the plurality of inorganic piezoelectric elements 2 The plurality of signal electrode
layers 44 are joined, whereby the upper organic layer 4 functions as an organic piezoelectric
material of the plurality of organic piezoelectric elements 5. Each of the organic piezoelectric
elements 5 arranged in this manner is composed of a dedicated signal electrode layer 44 and an
upper organic layer 41 and a ground electrode layer 43 common to the plurality of organic
piezoelectric elements 5. Therefore, the arrangement pitch of the plurality of organic
piezoelectric elements 5 is determined only by the arrangement pitch of the plurality of signal
electrode layers 44 joined on the back surface of the upper organic layer 41, and the plurality of
organic piezoelectric elements 5 are formed of a plurality of inorganic piezoelectric elements.
The elements are arranged at the same pitch P as the elements 2.
[0021]
Further, in each of the plurality of inorganic piezoelectric elements 2, the first acoustic matching
layer 3, the lower organic layer 42 of the second acoustic matching layer 4 and the plurality of
signal electrodes 44 separated by the same pitch P, A plurality of layers constituting the layers
from the plurality of inorganic piezoelectric elements 2 to the signal electrode layer 44 by
aligning and aligning in the stacking direction between the respective layers and filling the filler
between the respective rows. The separation part 6 is formed to separate the fragments of That
is, the separation portions 6 extend in parallel at the same pitch P in the stacking direction so as
to penetrate each layer from the surface of the signal electrode layer 44 to the surface of the
backing material 1 respectively. Furthermore, the acoustic lens 8 is bonded onto the plurality of
organic piezoelectric elements 5 via the protective layer 7.
[0022]
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The inorganic piezoelectric body 21 of the inorganic piezoelectric element 2 is formed of an
inorganic material for a piezoelectric body such as a Pb-based perovskite structure oxide. For
example, a Pb-based piezoelectric ceramic typified by lead zirconate titanate (Pb (Zr, Ti) O 3), or a
magnesium niobate / lead titanate solid solution (PMN-PT) and a zinc niobate / lead titanate solid
solution It can be formed from a relaxor-based piezoelectric single crystal represented by (PZNPT). On the other hand, the upper organic layer 41 of the organic piezoelectric element 5 is
formed of an organic material for a piezoelectric material such as a vinylidene fluoride (VDF)
material. For example, it can be formed from a polymeric piezoelectric element such as
polyvinylidene fluoride (PVDF) or polyvinylidene fluoride trifluoride ethylene copolymer (P (VDFTrFE)).
[0023]
The backing material 1 supports the plurality of inorganic piezoelectric elements 2 and absorbs
ultrasonic waves emitted backward, and can be formed of a rubber material such as ferrite
rubber. The first acoustic matching layer 3 is for efficiently causing the ultrasonic beams from
the plurality of inorganic piezoelectric elements 2 to be incident into the subject, and is
intermediate between the acoustic impedance of the inorganic piezoelectric elements 2 and the
acoustic impedance of the living body. It is formed of a material having an acoustic impedance of
value. The second acoustic matching layer 4 is for efficiently causing ultrasonic beams from the
plurality of inorganic piezoelectric elements 2 to enter the subject, and the lower organic layer
42 is made of an organic material, or an organic material and an inorganic material. It is
composed of a composite of materials. For example, the lower organic layer 42 is a vinylidene
fluoride (VDF) such as polyvinylidene fluoride (PVDF) or polyvinylidene trifluoride ethylene
fluoride copolymer (P (VDF-TrFE)) used in the upper organic layer 41. ) Can be formed from an
organic material containing a system material. The lower organic layer 42 can also be formed of,
for example, a composite material of an organic material and an inorganic material in which
zirconia particles are dispersed in an epoxy resin. The upper organic layer 41 and the lower
organic layer 42 are preferably formed of materials having the same or similar acoustic
impedance, for example, ultrasonic waves if the mutual acoustic impedance is in the range of ±
10%. The second acoustic matching layer 4 can be configured without affecting the acoustic
matching of Furthermore, the lower organic layer 42 can also be formed of a material having a
larger acoustic impedance than the upper organic layer 41 and a smaller acoustic impedance
than the first acoustic matching layer 3.
[0024]
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The filler that forms the separation portion 6 is for fixing the position and posture of the adjacent
fragments, and is formed of, for example, an epoxy resin or the like. The protective layer 7
protects the ground electrode layer 43 of the organic piezoelectric element 5 and is formed of,
for example, polyvinylidene fluoride (PVDF). If there is no problem in the protection of the
ground electrode layer 43, the acoustic lens 8 can be directly bonded on the plurality of organic
piezoelectric elements 5 without forming the protective layer 7. The acoustic lens 8 uses
refraction to narrow the ultrasonic beam to improve resolution in the elevation direction, and is
made of silicon rubber or the like.
[0025]
Next, the operation of this embodiment will be described. In operation, for example, the plurality
of inorganic piezoelectric elements 2 are used as transducers dedicated to transmission of
ultrasonic waves, and the plurality of organic piezoelectric elements 5 are used as transducers
dedicated to reception of ultrasonic waves. When a pulsed or continuous wave voltage is applied
between the signal electrode layer 22 and the ground electrode layer 23 of the plurality of
inorganic piezoelectric elements 2, the inorganic piezoelectric body 21 of each inorganic
piezoelectric element 2 expands and contracts to form a pulsed or continuous Wave ultrasound
is generated. These ultrasonic waves enter the subject through the first acoustic matching layer
3, the second acoustic matching layer 4, the protective layer 7 and the acoustic lens 8, are
combined with each other, and form an ultrasonic beam. It propagates in the subject.
[0026]
Subsequently, when the ultrasonic echo propagated and reflected in the object is incident on the
respective organic piezoelectric elements 5 through the acoustic lens 8 and the protective layer
7, the upper organic layer 41 is a harmonic of the ultrasonic wave. The components expand and
contract in response to high sensitivity, and an electric signal is generated between the signal
electrode layer 44 and the ground electrode layer 43 and is output as a reception signal. In this
manner, harmonic images can be generated based on the reception signals output from the
plurality of organic piezoelectric elements 5. Here, since the plurality of inorganic piezoelectric
elements 2 and the plurality of organic piezoelectric elements 5 are aligned with each other in
the stacking direction and arranged at the same pitch P, the subject is located at the same array
position as the ultrasonic beam transmission position It is possible to receive ultrasonic echoes
from H.V. and generate harmonic images with high accuracy.
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[0027]
In addition, a plurality of inorganic piezoelectric elements 2 can be used as transducers for
transmitting and receiving ultrasonic waves. In this case, the ultrasonic echo received by the
organic piezoelectric element 5 through the acoustic lens 8 and the protective layer 7 is further
transmitted through the second acoustic matching layer 4 and the first acoustic matching layer 3
to the respective inorganic piezoelectric elements. 2, and the inorganic piezoelectric body 21
expands and contracts mainly in response to the fundamental wave component of the ultrasonic
wave to generate an electric signal between the signal electrode layer 22 and the ground
electrode layer 23. Thus, based on the reception signal corresponding to the fundamental wave
component obtained from the plurality of inorganic piezoelectric elements 2 and the reception
signal corresponding to the harmonic wave component obtained from the organic piezoelectric
element 5, the fundamental wave component and the harmonics It is possible to generate a
compound image in which wave components are combined.
[0028]
Also at this time, since the plurality of inorganic piezoelectric elements 2 and the plurality of
organic piezoelectric elements 5 are aligned with each other in the stacking direction and
arranged at the same pitch P, the fundamental wave component and the harmonic component of
the ultrasonic echo are It is possible to receive at the same arrangement position, and to generate
a compound image in which the fundamental wave component and the harmonic wave
component are combined with high accuracy.
[0029]
Such an ultrasonic probe can be manufactured as follows.
First, as shown in FIG. 3A, the inorganic piezoelectric element layer 91a extending over the entire
surface of the backing material 1 is bonded onto the surface of the backing material 1 with an
adhesive or the like. In the inorganic piezoelectric element layer 91 a, conductive layers 92 and
93 are formed on both sides of the inorganic piezoelectric layer 91 extending over the entire
surface of the backing material 1. Next, as shown in FIG. 3B, the acoustic matching layer 94
extending over the entire area of the inorganic piezoelectric element layer 91a is bonded onto
the conductive layer 93 at a temperature of 80 ° C. to 100 ° C., for example. At this time, in the
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case of forming a sub-die on a plurality of inorganic piezoelectric bodies 21, the sub-die forming
groove is formed by dicing each layer of the acoustic matching layer 94 from the inorganic
piezoelectric element layer 91a or the inorganic piezoelectric element layer 91a. Can be formed.
Then, as shown in FIG. 3C, the organic layer 95 is bonded onto the acoustic matching layer 94.
The organic layer 95 has a size sufficient to extend over the entire surface of the acoustic
matching layer 94, and the conductive layer 96 is previously formed over the entire surface on
the surface opposite to the surface facing the acoustic matching layer 94.
[0030]
Subsequently, as shown in FIG. 3D, each layer is separated into a plurality of pieces by dicing
each layer of the conductive layer 96, the organic layer 95, the acoustic matching layer 94, and
the inorganic piezoelectric element layer 91a with a pitch P. Do. At this time, since dicing is
performed so as to completely separate the layers from the conductive layer 96 to the inorganic
piezoelectric element layer 91a, the respective pieces of the separated layers are aligned and
aligned in the stacking direction. Thereby, a plurality of inorganic piezoelectric elements 2
arranged at an arrangement pitch P are formed on the surface of the backing material 1, and the
first acoustic matching layer 3 and the lower organic layer are formed on the respective
inorganic piezoelectric elements 2. 42 and the respective portions of the signal electrode layer
44 are formed so as to sequentially overlap in position. Further, between the respective rows in
which the plurality of fragments of each layer are aligned at the pitch P in the stacking direction,
a plurality of flat plate-like grooves 97 penetrating each layer in the stacking direction are
formed by dicing. By dicing each layer from the conductive layer 96 to the inorganic
piezoelectric element layer 91a with the pitch P in this manner, each layer is simply separated
into a plurality of pieces and each piece of each separated layer is positioned in the stacking
direction It can be fitted. Then, the signal electrode layers 44 of the plurality of organic
piezoelectric elements 5 and the signal electrode layers 22 and the ground electrode layers 23 of
the plurality of inorganic piezoelectric elements 2 can be accurately aligned with each other.
[0031]
Next, the inside of the plurality of grooves 97 formed by dicing is filled with a filler to form the
separation portion 6 for fixing the position and posture of the plurality of fragments of each
layer as shown in FIG. 3 (E). After that, the upper organic layer 41 is pressure-bonded onto the
plurality of signal electrode layers 44 at a temperature of, for example, about 80.degree. The
upper organic layer 41 has a size sufficient to extend over the plurality of signal electrode layers
44, and on the surface opposite to the surface facing the plurality of signal electrode layers 44,
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the ground electrode layer 43 is provided in advance over the entire surface. It is formed.
[0032]
Here, the upper organic layer 41 constitutes a part of the second acoustic matching layer 4 for
acoustically matching the ultrasonic waves transmitted from the plurality of inorganic
piezoelectric elements 2, but The combined thickness of the side organic layers 42 may be set to
a value such that the desired acoustic matching is performed on the ultrasonic waves transmitted
from the plurality of inorganic piezoelectric elements 2. If attention is paid to the acoustic
matching, the upper organic layer 41 can be thinly formed to increase the electric capacity of the
organic piezoelectric element 5. That is, the upper organic layer 41 is formed to a desired
thickness having an electric capacity such that the ultrasonic echo received by the organic
piezoelectric element 5 is efficiently converted to a received signal. A range in which acoustic
matching is performed with respect to ultrasonic waves transmitted from the plurality of
inorganic piezoelectric elements 2 by combining the thickness of the upper organic layer 41 and
the lower organic layer 42 by adding the thickness of the lower organic layer 42 Form to fit
within. As described above, by forming the upper organic layer 41 thinner than the lower organic
layer 42, the second acoustic matching layer 4 performs acoustic matching with the ultrasonic
waves transmitted from the plurality of inorganic piezoelectric elements 2 The plurality of
organic piezoelectric elements 5 can be thinly formed while being formed within the range. The
sum of the thickness of the upper organic layer 41 and the thickness of the lower organic layer
42 is in the vicinity of a value satisfying the λ / 4 resonance condition with respect to the
wavelength λ of the fundamental wave transmitted from the plurality of inorganic piezoelectric
elements 2 Preferably it is formed.
[0033]
In addition, the upper organic layer 41 has a crystallization upper limit as its temperature
gradually decreases, so the upper limit temperature for use is at a temperature considerably
lower than the Curie point. For example, the high temperature of 80 ° C. to 100 ° C. used in
laminating the layers such as the acoustic matching layer 94 easily depolarizes it, but the upper
organic layer 41 has the protective layer 7 and the acoustic lens 8. Are stacked after the other
layers are stacked. Therefore, the upper organic layer 41 can be prevented from being
depolarized without being exposed to a high temperature when laminating other layers or when
the filler is filled in the groove 97. Furthermore, the layers stacked under the upper organic layer
41, that is, the signal electrode layer 22, the inorganic piezoelectric material 21, the ground
electrode layer 23, the first acoustic matching layer 3, the lower organic layer 42, and the signal
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electrode layer 44 Since the upper organic layer 41 is not present until successive bonding, these
layers can be bonded to each other at high temperature to be laminated with high adhesion. After
the upper organic layer 41 is stacked on the plurality of signal electrode layers 44 in this
manner, the acoustic lens 8 is bonded to the ground electrode layers 43 of the plurality of
organic piezoelectric elements 5 via the protective layer 7. The ultrasonic probe shown in FIGS. 1
and 2 is thus manufactured.
[0034]
For example, the frequency of ultrasonic waves transmitted from a plurality of inorganic
piezoelectric elements 2 is about 7 MHz, the acoustic impedance of the first acoustic matching
layer 3 is about 8.9 Mrayl (kg / m <2> s), and the second acoustic When making a linear probe
whose acoustic impedance of the matching layer 4 is about 4.0 Mrayl, lead zirconate titanate (Pb
(Zr, Ti) O 3) is used as the inorganic piezoelectric member 21 and its thickness is about 190 μm.
The first acoustic matching layer 3 can be formed to a thickness of about 80 μm. Then, PVDF is
used as the lower organic layer 42 and the upper organic layer 41, the lower organic layer 42 is
formed to a thickness of about 60 μm, and the upper organic layer 41 is formed to a thickness
of about 20 μm. By setting the thickness as a whole to about 80 μm, the plurality of organic
piezoelectric elements 5 can be formed to a desired thickness while the second acoustic
matching layer 4 satisfies the resonance conditions for the plurality of inorganic piezoelectric
elements 2 .
[0035]
When the lower organic layer 42 of the second acoustic matching layer 4 is formed of a
composite material of an organic material and an inorganic material, for example, the upper
organic layer 41 is made of polyvinylidene fluoride trifluoride ethylene copolymer (P (VDF-TrFE))
and has a thickness of about 10 μm, and the lower organic layer 42 is 70 μm using zirconia
particles dispersed in an epoxy resin so that the acoustic impedance is about 5 to 6 Mrayl. Form
to a certain thickness. Then, the first acoustic matching layer 3 is formed to a thickness of about
100 μm using a material in which zirconia particles are dispersed in an epoxy resin so that the
acoustic impedance is about 8 Mrayl. By configuring the first acoustic matching layer 3 and the
second acoustic matching layer 4 in this manner, the second acoustic matching layer 4 can
satisfy the resonance conditions for the plurality of inorganic piezoelectric elements 2 while the
plurality of organic piezoelectric elements are formed. 5 can be formed to a desired thickness.
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[0036]
Thus, the second acoustic matching layer 4 has a two-layer structure of the upper organic layer
41 and the lower organic layer 42, and the upper organic layer 41 constituting the plurality of
organic piezoelectric elements 5 is formed to a desired thickness. By forming the second acoustic
matching layer 4 so that the combined thickness of the upper organic layer 41 and the lower
organic layer 42 satisfies the resonance condition, it is excellent for ultrasonic beams transmitted
from a plurality of inorganic piezoelectric elements The acquisition efficiency of the reception
signal in the plurality of organic piezoelectric elements 5 can be improved while maintaining the
sound transmittance. Further, since the plurality of inorganic piezoelectric elements 2 and the
plurality of organic piezoelectric elements 5 are aligned with each other, highly accurate
harmonic images and compound images can be generated. Furthermore, since the upper organic
layer 41 functioning as the organic piezoelectric material of the organic piezoelectric element 5
is rarely exposed to a high temperature when manufacturing the ultrasonic probe, it is possible
to suppress the depolarization of the upper organic layer 41 it can.
[0037]
Incidentally, as shown in FIG. 4, the A / D converter 9 for inorganic piezoelectric element is
connected to the signal line electrode layer 22 of each inorganic piezoelectric element 2, and The
piezoelectric element amplifier 10 and the organic piezoelectric element A / D converter 11 can
be sequentially connected. Here, although the electric capacitances of the plurality of organic
piezoelectric elements 5 can be increased by setting the thickness of the organic piezoelectric
material small as described above, it is possible to obtain a reception signal having sufficient
strength by itself. It is difficult to amplify by the amplifier 10 for organic piezoelectric elements.
At this time, in order to prevent the reception signal from being attenuated while being
transmitted from the organic piezoelectric element 5 to the organic piezoelectric element
amplifier 10, the organic piezoelectric element amplifier 10 is in the vicinity of the signal line
electrode layer 44 of the organic piezoelectric element 5. It is preferable to connect or connect
directly. Further, by arranging a multiplexer in the ultrasonic probe, the number of signal lines
drawn from the ultrasonic probe can be reduced. For example, a multiplexer is disposed at the
subsequent stage of the inorganic piezoelectric element A / D converter 9 and the organic
piezoelectric element A / D converter 11, and the multiplexer is extracted from the inorganic
piezoelectric element A / D converter 9 and the organic piezoelectric element A / D converter 11.
Two signal lines can be combined into one.
[0038]
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In addition, although the lower organic layer 95 in which the conductive layer 96 is previously
formed on the surface is laminated on the first acoustic matching layer 94, the present invention
is not limited to this. The lower organic layer 95 may be laminated, and then the conductive layer
96 may be formed on the surface of the lower organic layer 95. Similarly, although the upper
organic layer 41 in which the ground electrode layer 43 is previously formed on the surface is
bonded onto the plurality of signal electrode layers 44, after the upper organic layer 41 is
bonded onto the plurality of signal electrode layers 42 The ground electrode layer 43 may be
formed on the surface of the upper organic layer 41.
[0039]
In the above embodiment, the ultrasonic waves generated by the plurality of inorganic
piezoelectric elements 2 are directed toward the subject and the ultrasonic echoes reflected in
the subject are the plurality of inorganic piezoelectric elements 2 or the plurality of plurality.
Although the light is received by the organic piezoelectric element 5, as shown in FIG. 5, the light
irradiation unit 31 irradiates the object with the light by newly providing the light irradiation unit
31 for irradiating the object with the irradiation light L. For example, the plurality of organic
piezoelectric elements 5 can receive the photoacoustic wave U (ultrasound) induced from the
subject by the irradiation of the light L and the irradiation of the irradiation light L. Thus, socalled photoacoustic imaging (PAI) can be performed in which the inside of the subject is imaged
using the photoacoustic effect. The light irradiator 31 sequentially irradiates a plurality of
irradiation lights L having different wavelengths toward the subject, and may be composed of a
semiconductor laser (LD), a light emitting diode (LED), a solid laser, a gas laser, etc. it can. The
light irradiation unit 31 uses, for example, pulse laser light as the irradiation light L, and
irradiates the pulse laser light toward the subject while sequentially switching the wavelength for
each pulse.
[0040]
When photoacoustic imaging is performed, the irradiation light L is irradiated from the light
irradiation unit 31 toward the subject, and when the irradiation light L thus irradiated is applied
to a predetermined living tissue V in the subject, the living body The tissue V absorbs the light
energy of the irradiation light L to emit a photoacoustic wave U (ultrasonic wave) which is an
elastic wave. For example, the object is sequentially irradiated with irradiation light L having a
wavelength of about 750 nm and irradiation light L having a wavelength of about 800 nm from
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the light irradiation unit 31. Here, oxygenated hemoglobin (hemoglobin combined with oxygen:
oxy-Hb), which is abundant in human arteries, has a higher molecular absorption coefficient with
respect to irradiation light L of wavelength 750 nm than irradiation light L of wavelength 800
nm. . On the other hand, deoxygenated hemoglobin (hemoglobin deoxy-Hb not bound to oxygen),
which is contained in a large amount in veins, has a lower molecular absorption coefficient with
respect to irradiation light L of wavelength 750 nm than irradiation light L of wavelength 800
nm. For this reason, when the illumination light L of wavelength 800 nm and the irradiation light
L of wavelength 750 nm are respectively irradiated to the artery and the vein, the photoacoustic
wave U of the intensity according to the molecular absorption coefficient of the artery and the
vein is respectively emitted. The photoacoustic wave U emitted from the artery or the vein is
received by the plurality of organic photoelectric elements 5 of the ultrasonic probe in the same
manner as in the above embodiment.
[0041]
Thus, the ultrasound probe can be used not only for ultrasound imaging but also for
photoacoustic imaging, and one ultrasound probe can be used to perform various ultrasound
diagnoses. It can be carried out. In addition, the photoacoustic wave U induced | guided | derived
from a test object by irradiation of irradiation light L can also be received by several inorganic
piezoelectric elements 2. FIG.
[0042]
DESCRIPTION OF SYMBOLS 1 backing material, 2 inorganic piezoelectric element, 3 1st acoustic
matching layer, 4 2nd acoustic matching layer, 5 organic piezoelectric element, 6 separating
part, 7 protective layer, 8 acoustic lens, 9 A / D for inorganic piezoelectric element Converter, 10
Amplifier for organic piezoelectric element, 11 A / D converter for organic piezoelectric element,
21 inorganic piezoelectric material, 22, 44 signal electrode layer, 23, 43 ground electrode layer,
41 upper organic layer, 42 lower organic layer, 91 Inorganic piezoelectric layer, 91a inorganic
piezoelectric element layer, 92, 93, 96 conductive layer, 94 acoustic matching layer, 95 organic
layer, 97 groove, 31 light irradiation part, P arrangement pitch, L irradiation light, U
photoacoustic wave.
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