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JP2001276067

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DESCRIPTION JP2001276067
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic probe, an ultrasonic diagnostic apparatus, and a method of manufacturing an
ultrasonic probe, and in particular, to tissue harmonic imaging (hereinafter referred to as THI).
And a ultrasonic probe suitable for harmonic imaging, an ultrasonic diagnostic apparatus using
the same, and a method of manufacturing the ultrasonic probe.
[0002]
[Prior Art] In the field of medical ultrasonic diagnostic equipment and nondestructive testing
equipment, PZT (zircon-lead titanate) based piezoelectric ceramics and relaxor-lead titanate
based piezoelectric single crystal materials are used as ultrasound transmitting / receiving
materials There is. If these are made into strip shaped transducers and individual transducers are
used for transmission and reception, the resolution and sensitivity can be significantly improved.
In these devices, an ultrasound probe is used as a transmission / reception device for imaging the
internal state of an object.
[0003]
Heretofore, a one-dimensional array probe using a PZT piezoelectric ceramic material has been
mainly used for these ultrasonic probes. As the one-dimensional array probe, an array type in
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which a plurality of strip-like transducers are arranged is often used. By controlling the timing of
the voltage pulse applied to each element, focusing, scanning and the like of the ultrasonic beam
are performed.
[0004]
However, recently, in order to further improve the resolution of the ultrasonic probe, research is
being made on a two-dimensional array probe in which rod-like transducers are arranged in two
dimensions. By using a small-sized but rod-like vibrator, its vibration mode can use k33 which is
a longitudinal vibration of the rod. This k33 is 60 to 80% for PZT-based ceramics and 80 to 94%
for relaxor-titanium-based single crystal materials, and high sensitivity can be expected.
[0005]
On the other hand, at present, in ultrasonic diagnostic apparatuses, THI technology has come to
be used to capture weak blood flow.
[0006]
In the THI technology, the second harmonic of the transmitted ultrasound (echo) is received and
detected.
Therefore, in a conventional ultrasonic probe adopting THI technology, the resonance frequency
of the piezoelectric element (the center frequency of the operating frequency band) should be
adjusted to either transmission or reception, or some other factor may be taken. It is inevitable
that the frequency characteristics of the piezoelectric element can not be fully utilized. As a
result, the drive voltage transmitted from the drive circuit needs to be increased more than
necessary, or the reception sensitivity is reduced.
[0007]
Further, for example, Japanese Patent Application Laid-Open No. 11-34797 discloses a technique
of performing transmission and reception of ultrasonic waves with different piezoelectric
elements. In this technology, while the receiving element is a single-layer piezoelectric element,
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2
the transmitting element has a laminated structure and the piezoelectric layer is made thinner to
improve the strength of ultrasonic waves to be transmitted. A body-based piezoelectric device of
the same thickness does not substantially change the center frequency within its operating
frequency band. Therefore, even if the technology described in JP-A-11-34797 is adopted for
THI, the reception sensitivity can not be greatly improved.
[0008]
Such problems become more serious in the case of a two-dimensional array probe because the
element size is reduced and the transmission / reception capability per element is reduced as
described above.
[0009]
On the other hand, in an ultrasonic probe such as a conventional two-dimensional array probe,
one piezoelectric element is divided into a two-dimensional array as disclosed in, for example, JPA-7-170600.
[0010]
When it produces by such a method, the ultrasonic probe which contained many non-defective
elements will become inferior goods by generation | occurrence | production of the slight
defective element by electrode peeling at the time of division | segmentation.
Therefore, the yield of the ultrasound probe is not improved.
[0011]
Further, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1134797, there is also a method of rearranging the respective elements after preparation and
arranging them again, but in order to narrow the element intervals and arrange the respective
elements equally, precise work is required. I needed it.
[0012]
As described above, in the conventional ultrasonic diagnostic apparatus using the THI
technology, it is necessary to increase the drive voltage transmitted from the drive circuit more
than necessary, or the reception sensitivity is increased. There was a problem that it decreased.
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[0013]
Moreover, in the production of a two-dimensional array, its manufacturability can not be
improved because it requires precise work.
[0014]
The present invention has been made in view of such problems, and is an ultrasonic diagnostic
apparatus compatible with THI technology and suitable for a low power and high sensitivity
ultrasonic diagnostic apparatus or an ultrasonic diagnostic apparatus using the THI technology.
It is an object of the present invention to provide a simple method of manufacturing a probe and
further this ultrasonic probe.
[0015]
A two-dimensional array ultrasonic probe according to the present invention comprises a first
transducer for emitting ultrasonic waves in a first operating frequency band, and a target of the
emitted ultrasonic waves. A second transducer having a second operating frequency band and
receiving a reflected wave from the sample, arranged in a two-dimensional plane, wherein the
second oscillator is arranged with respect to a central frequency of the operating frequency zone
of the first oscillator; A center frequency of the operating frequency band of the second vibrator
is high.
[0016]
Further, the first and second vibrators may be piezoelectric elements having substantially the
same external dimensions and made of piezoelectrics sandwiched by electrodes, and
piezoelectrics made of different piezoelectric materials can be used.
[0017]
Further, the first and second vibrators are formed of first and second piezoelectric elements
having substantially the same external dimensions, each of which has a piezoelectric body
sandwiched by electrodes, and the electrodes of the first piezoelectric element are the second
and third piezoelectric elements. It is formed in either a plane parallel to the dimensional plane
or a plane perpendicular to the two-dimensional plane, and an electrode of the second
piezoelectric element is a plane perpendicular to the two-dimensional plane orthogonal to the
electrodes of the first piezoelectric element. Or what was formed in either of the surface parallel
to the said two-dimensional surface can be used.
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[0018]
That is, by using a transducer having a different resonance frequency between the transducer for
ultrasonic wave transmission of the probe and the transducer for ultrasonic wave reception,
ultrasonic waves of different frequencies that are transmitted ultrasound are highly sensitive.
Made it possible to detect.
[0019]
In general, in the THI technology, since the ultrasonic wave to be received is the second
harmonic of the echo, it is preferable that the resonance frequency of the reception vibrator has
a resonance frequency on the higher frequency side than the transmission vibrator. Specifically,
it is preferable to use a vibrator having a resonance frequency on the high frequency side of
about 1.5 to about 3 times, and further about 2 times.
[0020]
The method of manufacturing an ultrasonic probe according to the present invention comprises
the steps of: forming a backing material having a plurality of parallel incisions on the surface of a
substrate; forming a plurality of piezoelectric elements; and forming a plurality of sheet wiring
boards Preparing, arranging the piezoelectric elements one-dimensionally on each of the sheetlike wiring boards, bonding the sheet-like wiring board and the piezoelectric elements, and
bonding the piezoelectric elements one-dimensionally arranged And inserting the obtained sheetlike wiring board into a plurality of incisions formed on the surface of the backing material, and
arranging the piezoelectric elements in a two-dimensional manner.
[0021]
As described above, since the transducers created in advance are arrayed to create an array, only
non-defective transducers can be arrayed, and the manufacturing yield of the probe can be
improved.
[0022]
In addition, when one vibrator is divided into an array, a predetermined cutting width is required,
and the arrangement pitch of the vibrators can not be narrowed. However, by arranging the
created vibrators, the arrangement pitch can be a desired value. Can be made smaller.
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This is particularly effective when each transducer area is small as in a two-dimensional array
probe.
[0023]
Further, by arranging the one-dimensionally arranged transducers on the sheet-like wiring
substrate and inserting the sheet-like wiring substrate in the backing material having the
incisions, the arrangement operation of the transducers can be simplified.
[0024]
The ultrasonic diagnostic apparatus according to the present invention transmits a ultrasonic
wave to a subject and has a first transducer having a first operating frequency band, and receives
a reflected wave of the transmitted ultrasonic wave from the subject. And a second transducer
having an operating frequency band in the two-dimensional plane, wherein the central frequency
of the operating frequency band of the first transducer is different from that of the operating
frequency band of the second transducer. A two-dimensional array ultrasound probe having a
high center frequency, a drive circuit connected to the first transducer to drive the first
transducer with a signal of a predetermined frequency, and connected to the second transducer
And a detection circuit for detecting an output signal obtained from the second vibrator and
extracting a second harmonic of the signal of the predetermined frequency.
[0025]
DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in
more detail with reference to the drawings.
[0026]
FIG. 1 is a schematic view showing an example of an ultrasonic diagnostic apparatus of the
present invention.
[0027]
The ultrasonic diagnostic apparatus 10 sends a drive signal to an ultrasonic probe 12 in which a
plurality of transducers (piezoelectric elements 11a and 11b having different central frequencies
in the operating frequency band) are arrayed, and the ultrasonic probe. A drive circuit 13, a
detector 14 for detecting a signal sent from the ultrasonic probe, and a display unit 15 for
displaying the detection result are formed.
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[0028]
The drive signal of the center frequency of the vibration frequency band of the vibrator 11a is
transmitted from the drive circuit 12, whereby ultrasonic waves are emitted from the ultrasonic
probe 12 toward the subject.
The reflected wave from the subject is received by the transducer 11 b whose center frequency
in the vibration frequency band is higher than the frequency of the drive signal.
The received signal is processed by the detector 14 to detect the second harmonic of the
reflected wave, and the result is displayed on the display unit 15.
[0029]
FIG. 2 is a perspective view showing an example of the ultrasound probe 12.
[0030]
As illustrated, the ultrasound probe 12 is configured by arranging a plurality of one-dimensional
piezoelectric element groups 12a and 12b arranged in the scan direction and a plurality of the
array in the slice direction to configure a two-dimensional array.
Each piezoelectric element group arranged one-dimensionally in the scan direction selectively
drives the transmitting transducers in the same scan row to scan ultrasonic waves while
converging them, and second-order reflected waves returning from the object The transducer
that receives the harmonics detects a state of a predetermined depth of the subject.
Further, by gradually shifting the convergence distance of the ultrasonic waves of the
piezoelectric element groups arranged one-dimensionally in the scan direction, it becomes
possible to find a cross section of a plane perpendicular to the two-dimensional array of the test
object. .
[0031]
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Further, as described in FIG. 1, in the ultrasound probe 12, the piezoelectric element 11 a
connected to the drive circuit and the piezoelectric element 11 b connected to the detector are
mixed.
One of the electrodes formed in the piezoelectric element 11a is connected to the drive circuit,
and the other electrode is grounded, and ultrasonic waves are transmitted from the piezoelectric
element 11a according to a drive signal from the drive circuit.
On the other hand, one of the electrodes formed on the piezoelectric element 11b is connected to
the detector, and the other is installed, and the ultrasonic wave received by the piezoelectric
element 11b is converted into an electrical signal and sent to the detector.
[0032]
In addition, an acoustic matching layer 22 is formed on the ultrasonic wave transmitting /
receiving surface of each piezoelectric element.
The acoustic matching layer 22 is provided to efficiently transmit ultrasonic waves between the
piezoelectric element and the test object.
[0033]
Furthermore, it is preferable to dispose a backing material (not shown) on the surface facing the
ultrasonic wave transmitting surface of the piezoelectric element, and to bond the piezoelectric
element 22 to the backing material.
A backing material is made of a material that attenuates ultrasonic waves, and has a function of
attenuating the ultrasonic waves emitted from the surface opposite to the ultrasonic wave
transmitting / receiving surface and preventing unnecessary vibration in the piezoelectric
element.
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[0034]
FIG. 3 is a perspective view showing an example of the piezoelectric elements 11a and 11b.
[0035]
The piezoelectric element includes a piezoelectric body 31 and at least a pair of electrodes 32
and 33 formed to apply an electric field to the piezoelectric body 31.
As described above, of the pair of electrodes, one electrode 32 is connected to a drive circuit or a
detector, and the other electrode 33 is grounded.
[0036]
The piezoelectric body 31 may be a known piezoelectric material such as PZT-based piezoelectric
ceramics or a relaxor / lead titanate-based piezoelectric single crystal material.
As a PZT-based piezoelectric ceramic, for example, a ternary material in which about 5 to 50
mol% of lead magnesium niobate (PMN), lead nickel niobate (PNN), or the like is dissolved in PZT
can be used.
Pb (B1B2) 1-xTixO3 (B1 is at least one selected from Zn, Mg, Ni, In, Sc, Yb and Lu, and B2 is
selected from Nb and Ta as a relaxor-lead titanate based piezoelectric single crystal material Or a
single crystal of a compound in which x is 0 to 0.55) or a compound in which a portion of lead of
this single crystal is substituted with at least one of Ba, Sr, Ca, and La, Specifically, Pb {(Zn1 /
3Nb2 / 3) 0.91Ti0.09} O3 (hereinafter referred to as PZNT 91/9) can be used.
[0037]
When it is used for THI, it is preferable that the center frequency of the operating frequency
band of the receiving element be close to twice the resonance frequency of the transmitting
element. Therefore, as a piezoelectric material used for a piezoelectric element for transmission,
In general, it is preferable to combine a relaxer-lead titanate-based piezoelectric single crystal
having a small frequency constant with a PZT-based piezoelectric ceramic as a piezoelectric
04-05-2019
9
element of a receiving element.
[0038]
In addition, although it is possible to control the resonance frequency by controlling the film
thickness of the piezoelectric element, it is preferable to set the thickness of both the
transmitting and receiving piezoelectric elements to the same value in consideration of the
manufacturing surface Specifically, the thickness of the piezoelectric body may be about 200 to
600 μm.
[0039]
The electrodes 32 and 33 form an electrode material mainly composed of Au, Ag, Pd, Sn or the
like.
[0040]
In forming the electrode, first, a base metal such as Ti or Cr is formed to a thickness of 0.02 to
1.0 μm by sputtering, and then a metal mainly composed of Au, Ag, Pd, or Sn, or an alloy thereof
To form a metal material having a thickness of 1 to 10 .mu.m by sputtering or another
appropriate method.
These electrodes can also be formed by screen printing, dipping, or thermal spraying other than
sputtering, using a conductive paste in which fine powder metal powder and low melting point
glass are mixed.
[0041]
Furthermore, a predetermined voltage is supplied between the electrodes 32 and 33 formed on
both sides of the piezoelectric body 31 to polarize the piezoelectric body, thereby obtaining a
piezoelectric element.
[0042]
A modification of the piezoelectric element is shown in FIG.
[0043]
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In the laminated piezoelectric element shown in FIG. 4, the first electrode 42 and the second
electrode 43 are sequentially laminated, and a piezoelectric body 41 layer is formed between the
respective electrodes.
And each 1st electrode 42 and each 2nd electrode 43 are connected by the side part of a
piezoelectric element, respectively.
[0044]
A predetermined voltage is applied between the first electrode 42 and the second electrode 43,
and as shown by an arrow in the figure, a voltage element is created by polarizing the adjacent
piezoelectric members 41 in the opposite direction. Can.
[0045]
Since the center frequency of the resonance frequency region of the piezoelectric element
obtained in this manner is determined by the total film thickness of the piezoelectric body 41,
when compared with the piezoelectric element using the single-layer piezoelectric body shown in
FIG. When piezoelectric elements of the same material and of the same size are manufactured,
the practical film thickness t is the same, and the center frequencies are substantially the same.
[0046]
The merit of the laminated piezoelectric element shown in FIG. 4 is that the voltage for driving
the piezoelectric element can be reduced because the distance between the electrodes is reduced.
When used in an ultrasonic diagnostic apparatus for THI, it is useful for transmission It is
particularly effective as a piezoelectric element.
[0047]
Another advantage is that the capacitance of the piezoelectric element can be increased.
For example, when a two-dimensional array probe is produced, the area of the ultrasonic wave
transmitting / receiving surface of each piezoelectric element becomes as small as 0.1 mm 2 or
less, so the electric capacitance of each element becomes small and is usually used as a drive
04-05-2019
11
signal. In the operating frequency range of 2 to 5 MHz, the impedance may be too large to obtain
impedance matching with the connection cable or the like. However, in the piezoelectric element
shown in FIG. In order to reduce the thickness of the element and increase the electric capacity of
the element, impedance matching with the connection cable can be obtained, and the signal noise
ratio can be increased.
[0048]
Next, an example of a method of manufacturing the laminated piezoelectric element will be
described with reference to FIG. 5 (in FIGS. 5a, b, d, e, f and g, the upper view is a plan view from
the upper surface and the lower view is a plane viewed from the side). Figure).
[0049]
For example, as shown in FIG. 5a, a plurality of piezoelectric bodies 51 made of a PZT ceramic
plate having a thickness of about 50 to 100 μm and a diameter of about 20 to 30 mm or a
relaxor-lead titanate single crystal plate is prepared (here The electrodes 52 are formed on both
sides of the piezoelectric body 51 as shown in FIG.
[0050]
In forming the electrode 52, first, a base metal such as Ti or Cr is formed to a thickness of 0.02 to
1.0 μm by a sputtering method, and then a metal mainly composed of Au, Ag, Pd, or Sn, and an
alloy thereof And optionally, a part of the insulating material is formed to a thickness of 1 to 10
μm by a sputtering method or another suitable method.
These electrodes can also be formed by screen printing, dipping, or thermal spraying other than
sputtering, using a conductive paste in which fine powder metal powder and low melting point
glass are mixed.
[0051]
As shown in FIG. 5c, the piezoelectric body 51 on which the electrodes 52 are formed is
laminated on the substrate 53 so that each electrode is in contact, and an appropriate weight 54
is placed on the top, and the temperature is 300 to 800 ° C. for 10 minutes. Heat to some
extent.
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The heat treatment temperature varies depending on the electrode material.
For example, in the case of 80 Au / 20 Sn or 95 Sn / 5 Ag, the bonding can be performed even at
about 300 ° C.
However, in 70Pd / 30Ag, sufficient bonding strength can not be obtained unless the
temperature is about 800.degree.
[0052]
The laminate thus obtained, as shown in FIG. 5 d, is cut at a width of about 0.2 to 0.5 mm to
obtain a plurality of strip-like laminates as shown in FIG. 5 e.
[0053]
Furthermore, as shown in FIG. 5 f, the electrodes 52 are coated every other layer with the
insulating glass material 55 on the side surface of the strip-like laminate, and the laminate is
continuously formed from the top of the glass material 55 as shown in FIG. An external electrode
56 is formed on the side surface.
[0054]
In FIG. 5g, the glass material 55 is coated on the second and fourth layer electrodes 52, and the
side surfaces where the first, third, and fifth layer electrodes are connected are shown. The first,
third, and fifth layers are coated with a glass material 55, and the electrodes of the second and
fourth layers are electrically connected.
[0055]
While the voltage (electric field) of 0.1 to 2 kV / mm is applied to the pair of opposed electrodes
56 of the laminated body shown in FIG. 5g, cooling is performed from 200 ° C. to 20 ° C. to
polarize the piezoelectric body 51. The piezoelectric characteristics were given.
[0056]
Furthermore, as shown in FIG. 5h, the laminate is cut at a width of 0.2 to 0.5 mm to produce the
piezoelectric element shown in FIG. 5i (FIG. 5h also shows a plan view showing the side surface
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of the piezoelectric element) .
[0057]
Below, the production method of an ultrasound probe is explained more concretely.
[0058]
(1) Preparation of Transmission Element A PZNT 91/9 solid solution single crystal was used as a
piezoelectric body, and this single crystal (001) plate was cut into 20 mm × 20 mm and polished
to a thickness of 100 μm.
A conductive paste obtained by adding glass paste to Au / Pt was applied to the opposing surface
of this single crystal plate, and a baked electrode was formed at 650 ° C.
Five sheets of the piezoelectric body on which this electrode was formed were laminated, and
further heat compression was applied at 700 ° C. for 10 minutes.
[0059]
The resulting laminate is cut to a width of 0.25 mm, and the first, third and fifth layer electrode
surfaces of one cut surface and the second, fourth and sixth layer electrode surface low melting
point glass of the other cut surface are used. It was formed and insulated at 550 ° C.
Thereafter, external electrodes were formed on each cut surface by sputtering.
[0060]
The laminated body on which the external electrode was formed was cut at intervals of 0.25 mm
to prepare a piezoelectric element of 0.25 mm × 0.25 mm and a thickness of 0.5 mm.
[0061]
Furthermore, a voltage of 0.3 kV / mm (about 30 V) was applied between the external electrodes
04-05-2019
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at 180 ° C. to polarize the piezoelectric body, and its characteristics were evaluated. The center
frequency was about 2.0 MHz, and the coupling coefficient k33 was 80%.
[0062]
The characteristics of each element were evaluated, and only good products were prepared.
[0063]
(2) Preparation of Receiving Element The piezoelectric material of the receiving element was
made of PZT ceramic.
[0064]
Production is a common green sheet lamination method.
First, a green sheet of PZT-based material having a thickness of 20 to 100 μm is produced using
a sheet molding machine.
A predetermined pattern is printed on the upper surface of the green sheet using an electrode
paste mainly composed of Pt, Pd, Ag or the like.
These sheets are accurately positioned and laminated.
Thereafter, it is cut into individual elements, degreased, fired, and provided with external
electrodes in the same manner as the transmission side elements, to complete individual
elements.
The dimensions of the element are 0.25 mm × 0.25 mm and 0.5 mm thick.
[0065]
A voltage of 2 kV / mm was applied at 80 ° C. between the external electrodes of this
piezoelectric element to polarize the piezoelectric body.
04-05-2019
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[0066]
The electrostatic capacitance of this laminated piezoelectric element was 200 pF, the resonance
frequency was about 3.0 MHz, and the coupling coefficient k33 was 65%.
[0067]
Piezoelectric elements for reception were prepared in the same manner as the transmitting
elements, and the characteristics of each element were evaluated. Only 2000 non-defective
products were prepared.
[0068]
In the present embodiment, as a method of making the resonance frequency of the piezoelectric
element different, a method of making the material used for the piezoelectric body different is
adopted, but the film thickness of the piezoelectric body is different or A method of making the
polarization directions of the body different may be adopted, and furthermore, a dual frequency
element or the like may be used as the receiving element.
[0069]
However, in consideration of arranging the piezoelectric elements so that the ultrasonic
transmitting / receiving surface is flat, it is preferable to make the thickness of the piezoelectric
elements substantially uniform.
[0070]
Further, as a method of using different piezoelectric materials, it is more preferable that the
central frequency of the operating frequency range of the ultrasonic wave receiving element be
higher than the resonance frequency of the ultrasonic wave transmitting element, more
preferably 1.5 to 2 times It is desirable to use a piezoelectric body that is somewhat larger.
[0071]
In the method of making the relationship between the ultrasonic transmitting / receiving surface
and the polarization direction of the piezoelectric body different, for example, the transmitting
element arranges the polarization direction in the same direction as the surface direction of the
ultrasonic transmitting / receiving surface, and the receiving element has the polarization
direction Of the two piezoelectric elements of the so-called two types of piezoelectric elements,
etc. are generated in the vibration mode of k33, and the other piezoelectric element is The
04-05-2019
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ultrasound generated in the mode is disposed in a direction that can be emitted from the
ultrasound transmission / reception surface.
[0072]
In the method using dual-frequency elements, single-layer or multilayer piezoelectric elements as
shown in FIGS. 3 and 4 are used for the transmitting elements, and cross-sections as shown in
FIGS. 9A and 9B for the receiving elements. Use a dual frequency element having a structure.
[0073]
FIG. 9 is a view showing an example of a dual frequency element.
For example, as shown in (a), a first electrode 93 and a second electrode 94 are formed on both
sides of the piezoelectric body 91 having a polarized piezoelectric body 91 and a nonpolarization material 92 having no piezoelectric property. (B) is formed by laminating a first
electrode 95, a first piezoelectric body 96, a second electrode 97, a second piezoelectric body 98
and a third electrode 99, and It is a piezoelectric element in which the piezoelectric body 96 and
the second piezoelectric body 98 are polarized in opposite directions.
[0074]
In such a two-frequency element, as shown in FIG. 9C, the frequency characteristic has two band
characteristics of the frequency f1 of the transmitting element and its second harmonic f2 (f2 =
f1 × 2). It is possible to efficiently detect not only the wave component but also the conventional
fundamental wave component, and harmonic images such as THI and conventional basics create
a good S / N image with a tomographic image using the component. It is possible.
(3) Preparation of a two-dimensional array ultrasonic probe As shown in (1) and (2), an
ultrasonic probe is arranged by arranging two kinds of piezoelectric elements for transmission
and reception with different resonance frequencies. Configure
[0075]
FIG. 6 is a diagram showing an example of a method of manufacturing an ultrasound probe.
04-05-2019
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[0076]
The two types of piezoelectric elements 61 described above are one-dimensionally arrayed on
the sheet-like wiring substrate 63 on which the circuit wiring 62 is formed.
By aligning the ultrasonic transmission / reception surface of each piezoelectric element with the
end of the sheet-like wiring board 63, it becomes possible to arrange the ultrasonic transmission
/ reception surface of each piezoelectric element in a straight line.
[0077]
The circuit wiring 62a may be connected to the drive circuit or connected to the detector. For
example, the laminated piezoelectric element may be connected to the circuit wiring connected to
the drive circuit, and the single layer element may be connected to the detector. Connect to the
circuit wiring.
The circuit wiring 62b is grounded.
[0078]
If the number of receiving elements is too large, the size of the receiving circuit will increase,
resulting in an increase in system size, cost increase, etc. If too small, the receiving sensitivity will
be lowered (S / N degradation of received signal). Become.
[0079]
Similarly, a plurality of sheet-like wiring boards in which piezoelectric elements are onedimensionally arrayed are prepared.
[0080]
Next, a method of arranging the piezoelectric elements two-dimensionally will be described.
04-05-2019
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[0081]
FIG. 7 is a perspective view of a backing material on which the piezoelectric element is mounted.
[0082]
The backing material 71 is formed on the surface of a predetermined substrate 72 such as
ceramic.
The backing material 71 is formed of a material having high ultrasonic absorbability, such as
rubber.
Parallel notches 73 are formed in the backing material 71 at equal intervals.
[0083]
Alternatively, a backing material 71 on a strip, which has been divided into the same shape in
advance, may be bonded in parallel to the surface of the ceramic substrate 72 to form a backing
material as shown in FIG.
[0084]
FIG. 8a is a cross-sectional view when the piezoelectric elements 61 are two-dimensionally
arranged on the backing material 71, and FIG. 8b is a perspective view.
[0085]
The sheet-like wiring substrate 63 in which the piezoelectric elements 61 described above are
arranged in a one-dimensional manner is inserted into the notches 73 formed in the backing
material 71 until the piezoelectric elements 61 contact the bucking member.
By so doing, it becomes possible to arrange the one-dimensionally arranged piezoelectric
elements two-dimensionally such that the ultrasonic transmitting / receiving surfaces become
planar at equal intervals.
04-05-2019
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[0086]
In such a manufacturing method, in order to fix the sheet-like substrate 63 by the incised portion
73, the depth of the incised portion needs to be equal to or more than the length of the inserted
sheet substrate.
Furthermore, after the sheet substrate is inserted into all the grooves, the signal line end of the
sheet substrate 63 is exposed on the bottom surface of the backing material 71 by removing the
substrate 72.
In addition, by bonding the piezoelectric element 61 and the backing material 71 using an
adhesive or the like, it is possible to fix the piezoelectric element 61 or the sheet-like substrate
63 and the backing material 71.
[0087]
Furthermore, by forming an acoustic matching layer on the ultrasonic transmitting and receiving
surface of the two-dimensional array obtained in this manner, an ultrasonic probe is produced.
[0088]
By preparing the ultrasonic probe in this manner, it is possible to simply arrange the onedimensionally arrayed piezoelectric element array in a two-dimensional plane.
In addition, since defective elements generated when dividing the piezoelectric element can be
removed in advance, the manufacturing yield of the ultrasonic probe can be improved.
[0089]
In the obtained ultrasonic probe, an ultrasonic wave of about 2.0 MHz is emitted from the
transmitting piezoelectric element.
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Since the center frequency of the operating frequency range of the receiving element for
receiving the second harmonic, that is, the echo centered on the frequency 4.0 MHz is as high as
3.0 MHz, the reception sensitivity of the second harmonic is improved. It becomes possible to
suppress the voltage applied to the reliable piezoelectric element.
[0090]
As described above, according to the ultrasonic probe and the ultrasonic diagnostic apparatus of
the present invention, since the reception sensitivity of ultrasonic waves is enhanced, it is
possible to suppress the drive voltage for ultrasonic wave transmission. it can.
Further, according to the method of manufacturing an ultrasonic probe of the present invention,
it is possible to arrange the piezoelectric elements in a two-dimensional plane by a simple
method.
Alternatively, the manufacturing yield of the ultrasonic probe can be improved.
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