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JP2012129662

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2012129662
An ultrasonic probe capable of efficiently receiving a reflected wave and improving sensitivity
and operational reliability even when variations occur in the frequency band of ultrasonic waves
to be transmitted. A receiving unit using a capacitive vibration element receives a reflected wave
of ultrasonic waves transmitted from a transmitting unit using a piezoelectric vibration element.
The use of the capacitive vibration element as compared with the case of using the piezoelectric
vibration element can cope with the case where the frequency band of the ultrasonic waves
transmitted from the transmission unit is dispersed because the used ultrasonic frequency band
is wider. [Selected figure] Figure 1
Ultrasound probe
[0001]
The present invention relates to an ultrasonic probe that transmits an ultrasonic wave to an
object and receives a reflected wave reflected from the object.
[0002]
In recent years, in medical ultrasound diagnosis, an ultrasonic wave generated by a probe is
transmitted into the body, and a reflected wave reflected by an organ or the like in the body is
received by the probe to detect an abnormality in the body (non-patent) Reference 1).
[0003]
Such a technology includes a single element (piezoelectric vibration element) made of a
piezoelectric ceramic material, and by switching this element in time, an ultrasonic transmission
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element for transmission and an ultrasonic reception element for reception A dual-purpose
transducer is used.
[0004]
Further, the transmission oscillator and the reception oscillator are provided, the fundamental
wave is transmitted into the living body, the wide band signal in which the fundamental wave and
the harmonics are mixed is received by the reception oscillator, and the received broadband is
received. There is disclosed an ultrasonic diagnostic apparatus which inputs a signal to a data
conversion unit and performs predetermined processing (see Patent Document 1).
[0005]
Unexamined-Japanese-Patent No. 2003-265466
[0006]
G. Calioano, R.S. Carotenuto, A. Caronti and M. Pappalardo, "cMUT echographic probes: Design
and fabrication process" 2002, IEEE Ultrasonic Symposium, pp 1067-1070.
[0007]
On the other hand, although the piezoelectric vibration element has high transmission output, its
processing accuracy is relatively low, so when it is miniaturized, the usable frequency band of
ultrasonic waves is limited, and the error of the resonance frequency of each array element or
diagnostic image There are issues such as resolution degradation of
That is, even if manufactured in the same process, it can be used as a frequency band of
ultrasonic waves that can be used (hereinafter, referred to as a used ultrasonic frequency band.
May not be obtained, and may show lower resolution than expected.
[0008]
In addition, as in the ultrasonic diagnostic apparatus of Patent Document 1, another piezoelectric
vibration element (reception vibrator) receives ultrasonic waves transmitted from one
piezoelectric vibration element (transmission vibrator). In this case, the variation in the used
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ultrasonic frequency band in the receiving transducer is further added to the variation in the
used ultrasonic frequency band in the transmitting transducer, and the sensitivity may be
lowered in the entire apparatus.
[0009]
On the other hand, the frequency band of the piezoelectric vibration element is relatively narrow
(≦ 80%), and the capacitance type element exhibits a relatively wide frequency band (≧ 110%).
Therefore, when the capacitive element is used as a receiving element, stable transmission /
reception sensitivity can be exhibited even if frequency variations of the transmitting element
occur.
[0010]
The present invention has been made in view of such circumstances, and an object of the present
invention is to efficiently receive a reflected wave, even when the frequency band of an ultrasonic
wave to be transmitted varies. It is an object of the present invention to provide an ultrasound
probe which can further enhance sensitivity.
[0011]
An ultrasonic probe according to the present invention transmits an ultrasonic wave to an object
and receives the reflected wave reflected by the object, the ultrasonic probe using the
piezoelectric vibration element in the ultrasonic probe. A transmitting unit for transmitting and a
receiving unit for receiving the reflected wave using a capacitive vibration element are
characterized.
[0012]
In the present invention, the reception unit using the capacitive vibration element receives the
reflected wave of the ultrasonic wave transmitted from the transmission unit using the
piezoelectric vibration element.
The use of the capacitive vibration element as compared with the case of using the piezoelectric
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vibration element can cope with the case where the frequency band of the ultrasonic waves
transmitted from the transmission unit is dispersed because the used ultrasonic frequency band
is wider.
[0013]
The ultrasound probe according to the present invention is characterized by including a backing
portion interposed between the transmitting portion and the receiving portion.
[0014]
In the present invention, a backing unit is interposed between the transmitting unit and the
receiving unit, and the backing unit acoustically isolates the transmitting unit and the receiving
unit.
[0015]
The ultrasound probe according to the present invention is characterized by comprising an
insulating portion interposed between the backing and the receiving portion.
[0016]
In the present invention, an insulating portion is interposed between the backing and the
receiving portion, and the insulating portion electrically isolates the transmitting portion and the
receiving portion.
[0017]
The ultrasound probe according to the present invention is characterized in that the transmission
unit has a convex curved surface for diffusing ultrasound.
[0018]
In the present invention, the transmitter has a curved surface convex toward the object, and the
ultrasonic wave transmitted from the transmitter travels while being diffused toward the object
by the curved surface. .
[0019]
The ultrasonic probe according to the present invention is characterized in that the receiving unit
includes a transducer array in which a plurality of capacitive transducer elements are arranged in
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one or two dimensions.
[0020]
In the present invention, since the receiving unit receives the reflected wave using a vibrating
element array in which a plurality of capacitive vibrating elements are arranged in one or two
dimensions, it is possible to receive the reflected wave from any direction. The reflected wave can
be selectively received.
[0021]
In the ultrasonic probe according to the present invention, in the transmission unit, the
piezoelectric vibrating element is interposed between two opposing electrodes, and a through
hole penetrating the transmission unit in the opposing direction of the electrodes. It is
characterized by having.
[0022]
In the present invention, in the opposite direction of the two electrodes of the transmitter, there
is a through hole penetrating the transmitter, another tool is inserted through the through hole,
or the other through the through hole. Can be equipped with
[0023]
The ultrasound probe according to the present invention is characterized in that the transmission
unit includes an acoustic lens that controls the beam of the ultrasound.
[0024]
In the present invention, the transmission unit includes an acoustic lens, and the acoustic lens
diffuses or focuses the ultrasonic waves transmitted from the transmission unit.
[0025]
In the ultrasonic probe according to the present invention, the receiving unit includes a first
electrode plate whose one surface faces the object, and a second electrode plate whose one
surface opposes the other surface of the first electrode plate. A backing portion is provided on
the other surface side of the second electrode plate.
[0026]
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In the present invention, a backing portion is provided on the other surface side of the second
electrode plate of the receiving portion, and the vibration of the transmitting portion after
transmitting the ultrasonic wave to the object side (forward) is attenuated. Absorbs transmitted
ultrasound that has been emitted to the rear of the
Further, the backing unit absorbs the reflected wave that has passed through the receiving unit
when the reflected wave is received.
[0027]
According to the present invention, even if variations occur in the frequency band of ultrasonic
waves transmitted from the transmitter using the piezoelectric vibrator, the receiver using the
capacitive vibrator efficiently reflects waves. Since it can receive, it can provide an ultrasonic
probe which can raise sensitivity more.
[0028]
It is a schematic diagram which shows the principal part structure of the hybrid type | mold
ultrasonic probe which concerns on Embodiment 1 of this invention.
It is a graph which compares the ultrasonic frequency band of a piezoelectric type vibration
element and an electrostatic capacitance type vibration element.
It is a longitudinal cross section by the III-III line of FIG.
FIG. 4 is an enlarged view of a portion A of FIG. 3;
It is the enlarged view which partially expanded B part of FIG.
It is a schematic diagram which shows the principal part structure of the hybrid type | mold
ultrasonic probe which concerns on Embodiment 2 of this invention.
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It is a schematic diagram which shows the principal part structure of the hybrid type | mold
ultrasonic probe which concerns on Embodiment 3 of this invention.
It is a longitudinal cross-sectional view by the VIII-VIII line of FIG.
It is a typical longitudinal cross-sectional view which shows the principal part structure of the
hybrid type | mold ultrasonic probe which concerns on Embodiment 4 of this invention.
It is a typical longitudinal cross-sectional view which shows the principal part structure of the
hybrid type | mold ultrasonic probe which concerns on Embodiment 5 of this invention.
[0029]
The ultrasonic probe according to the present invention transmits ultrasonic waves to an object
(for example, an organ in the body) and receives a reflected wave reflected by the object, and
uses a piezoelectric vibration element. This is a so-called hybrid ultrasonic probe including a
transmitting unit and a receiving unit using a capacitive vibration element.
The hybrid ultrasonic probe according to the present invention will be described in detail below
based on the drawings.
[0030]
First Embodiment FIG. 1 is a schematic view showing a main part configuration of a hybrid
ultrasonic probe according to a first embodiment of the present invention.
[0031]
The hybrid ultrasonic probe 1 according to the first embodiment of the present invention has, for
example, a circular bottomed cylindrical casing 6 having a diameter of 1.2 cm.
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The casing 6 has a circular opening 61 at the front end on the object side, and the opening 61
receives the transmitter 2 for transmitting the ultrasonic wave to the object, and the reception
for receiving the reflected wave from the object A part 3 is provided.
The transmitting unit 2 transmits an ultrasonic wave using a piezoelectric vibrating element
described later, and the receiving unit 3 receives a reflected wave from the object using a
capacitive vibrating element described later.
The present invention is not limited to the dimensions described above.
[0032]
FIG. 2 is a graph comparing ultrasonic frequency bands of the piezoelectric vibrating element
and the capacitive vibrating element.
As indicated by a dotted line in FIG. 2, in general, the piezoelectric vibration element is
characterized in that the ultrasonic frequency band is narrower than that of the capacitive
vibration element, but the transmission output is high and the reception sensitivity is good.
However, since processing accuracy is limited, an error of the resonance frequency is generated,
and there is a problem that the frequency band becomes narrow due to the material and
structural characteristics of the piezoelectric ceramic element itself.
That is, there are many cases where variations occur in the used ultrasonic frequency band also
between the piezoelectric vibrators manufactured in the same process.
[0033]
On the other hand, as indicated by the solid line in FIG. 2, the capacitive vibration element has
relatively good reception sensitivity although it is lower than the piezoelectric vibration element,
and the ultrasonic frequency band used is piezoelectric vibration. It is significantly wider than the
element.
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[0034]
In the hybrid ultrasonic probe 1 according to the first embodiment of the present invention, as
described above, the transmitting unit 2 transmits ultrasonic waves using a piezoelectric vibrator,
and the receiving unit 3 is a capacitive vibration. Since the element is used to receive the
reflected wave, it is possible to cope with the case where the frequency band of the ultrasonic
wave transmitted from the transmission unit 2 is somewhat dispersed.
[0035]
The transmitting unit 2 is provided in a predetermined range in the radial direction from the
center of the casing 6, and the receiving unit 3 is provided in the vicinity of the peripheral edge
of the casing 6 so as to surround the transmitting unit 2.
[0036]
FIG. 3 is a longitudinal cross section taken along line III-III of FIG.
[0037]
The transmitting unit 2 has, for example, a disk shape having a thickness of 0.1 mm, and the
receiving unit 3 has an annular shape having a thickness equal to that of the transmitting unit 2.
A backing unit 4 is interposed between the transmitter 2 and the receiver 3 as described above.
In addition, an insulating portion 5 is interposed between the backing portion 4 and the receiving
portion 3.
In other words, the backing portion 4 is provided to surround the transmission portion 2, and the
insulating portion 5 is provided to surround the backing portion 4.
In addition, it is not limited to the dimensions described above.
[0038]
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The backing unit 4 is made of, for example, a resin, and acoustically isolates the receiving unit 3
and the transmitting unit 2.
In detail, the backing unit 4 attenuates the vibration of the transmitting unit 2 after transmitting
the ultrasonic wave forward, and further absorbs the transmitted ultrasonic wave radiated to the
rear of the transmitting unit 2 by reflection or the like. While suppressing the disorder of a
transmission ultrasonic wave, the acoustic influence on the adjacent receiving part 3 is prevented
beforehand.
Furthermore, when the receiving unit 3 receives a reflected wave, the backing unit 4 absorbs the
reflected wave that has passed through the receiving unit 3 to prevent the acoustic influence on
the adjacent transmitting unit 2 in advance.
[0039]
The backing unit 4 is formed not only between the transmitting unit 2 and the receiving unit 3
but also behind the transmitting unit 2 and the receiving unit 3.
The backing unit 4 between the transmission unit 2 and the reception unit 3 and the backing unit
4 behind the transmission unit 2 and the reception unit 3 are integrally formed.
[0040]
The insulating unit 5 electrically isolates the receiving unit 3 and the transmitting unit 2. The
insulating unit 5 is made of, for example, a band-like conductive metal, and is configured to be
connected to the GND. Further, the insulating portion 5 is configured such that the dimension in
the width direction is equal to that of the receiving portion 3.
[0041]
In the hybrid ultrasonic probe 1 according to the first embodiment of the present invention, in
the transmission unit 2, the piezoelectric vibration element is driven at a high voltage, and the
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reception unit 3 adjacent to the transmission unit 2 has a capacitance Although the mold
vibrating element is configured to receive the reflected wave with high impedance, the insulating
unit 5 can suppress electrical coupling between the transmitting unit 2 and the receiving unit 3
to isolate each other.
[0042]
FIG. 4 is an enlarged view of a portion A of FIG. 3.
[0043]
The receiving unit 3 includes a vibrating membrane 31 vibrating when receiving a reflected
wave, a vibrating electrode 32 (first electrode plate) formed on the front surface of the vibrating
membrane 31 and vibrating with the vibrating membrane 31, and a back surface of the vibrating
electrode 32. And a substrate 34 provided on the back side of the opposite electrode 33, which is
a so-called electrostatic capacitance type vibration element.
[0044]
The vibrating film 31 has a thickness of 0.1 to 10.0 μm, and has, for example, a residual tensile
stress of 100 MPa or less, and is made of Si 3 N 4, Si single crystal, polycrystalline Si thin film or
the like.
[0045]
The substrate 34 is, for example, a crow substrate (PYREX (registered trademark)) or a silicon
wafer.
A vibrating film support (not shown) for supporting the vibrating film 31 is formed on the front
surface of the substrate 34, and the vibrating film 31 and the vibrating electrode 32 are
supported by the vibrating film support.
[0046]
On the other hand, the vibrating electrode 32 and the counter electrode 33 are made of Al, Pt /
Ti, Cr, etc., and have a film shape of 0.01 to 0.3 μm in thickness. It is deposited.
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[0047]
In the receiving unit 3, the vibrating electrode 32 and the counter electrode 33 are electrically
connected to the outside, and an electrical signal related to the change in capacitance between
the counter electrode 33 and the vibrating electrode 32 is output.
For example, an image of an object can be obtained based on the electrical signal.
[0048]
FIG. 5 is an enlarged view of a portion B of FIG. 3.
The transmission unit 2 of the hybrid ultrasonic probe 1 according to the first embodiment uses,
for example, a 1-3 composite vibration element 25 which is a composite material of a
piezoelectric element and a resin.
In addition, as piezoelectric elements for transmission, various piezoelectric ceramic elements
such as ZnO2 single crystal, Diaphram type thin film piezoelectric element (PZT thin film) other
than 1-3 composite can be used.
[0049]
Specifically, the transmitting unit 2 includes a plurality of rectangular piezoelectric elements 23
arranged in a two-dimensional shape and having a width of 3 μm, and a filler 22 filled between
and around the plurality of piezoelectric elements 23 (for example, epoxy System resin).
[0050]
The plurality of piezoelectric elements 23 are arranged with a predetermined gap therebetween
in order to reduce mutual interference such as crosstalk.
In addition, in order to reduce mutual interference between the piezoelectric elements 23 and to
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suppress lateral vibration of the piezoelectric elements 23 so that the piezoelectric elements 23
vibrate only in the vertical direction, the filling material 22 includes a plurality of piezoelectric
elements. It is filled between and around 23.
[0051]
In front of the piezoelectric element 23 and the filler 22, a common ground electrode 21 made of
a conductive material and connected to each piezoelectric element 23 is provided.
An electrode line from the common ground electrode 21 is drawn to the front of the transmission
unit 2 and connected to GND.
[0052]
On the other hand, behind the piezoelectric element 23 and the filler 22, driving electrodes 24
connected to the respective piezoelectric elements 23 are provided. The drive electrode is pulled
out via the backing portion 4.
[0053]
In the hybrid ultrasonic probe 1 according to the first embodiment of the present invention, since
the piezoelectric element 23 is polarized in the longitudinal direction (longitudinal direction), a
voltage is applied between the common ground electrode 21 and the drive electrode 24. When
applied, an electric field is formed in the vertical direction to vibrate the piezoelectric element 23.
[0054]
As described above, the hybrid ultrasonic probe 1 according to the first embodiment uses the
capacitive vibration element as the receiving unit 3, so a plurality of signal lines from the drive
electrode 24 are interposed through the backing unit 4. Can be omitted.
Therefore, both the transmitting unit 2 and the receiving unit 3 have a simple structure, improve
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the reliability in operation, and reduce the manufacturing cost as compared with the
conventional one using the piezoelectric vibration element.
[0055]
Second Embodiment FIG. 6 is a schematic view showing a main configuration of a hybrid
ultrasonic probe according to a second embodiment of the present invention. In the hybrid
ultrasonic probe 1 according to the second embodiment, the receiving unit 3 includes an array of
capacitive vibration elements arranged in one or two dimensions. FIG. 6 (a) shows an example of
a hybrid ultrasonic probe 1 having an array 10 of capacitive vibrating elements arranged in one
dimension, and FIG. 6 (b) is arranged in two dimensions. An example of a hybrid ultrasound
probe 1 having an array 10 of capacitive transducers is shown.
[0056]
In the hybrid ultrasonic probe 1 shown in FIG. 6A, in the receiving unit 3, capacitive element
transducer elements 35, 35, ... are arranged in respective regions divided in the circumferential
direction. And an array 10 of capacitive vibration elements. The configuration of each element
vibrating element 35 is the same as that of the first embodiment, and the detailed description will
be omitted.
[0057]
In the hybrid ultrasonic probe 1 shown in FIG. 6 (b), in the receiving unit 3, each region divided
in the circumferential direction is further divided in the radial direction, and each region formed
by this The element vibrating elements 35, 35,... 35 are arranged in FIG. The configuration of the
element vibrating element 35 is the same as that of the first embodiment, and the detailed
description will be omitted.
[0058]
About the part similar to Embodiment 1, the same code | symbol is attached | subjected and
detailed description is abbreviate | omitted.
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[0059]
The hybrid ultrasonic probe according to the second embodiment of the present invention, as
described above, has the array 10 of capacitive vibration elements, so reception of the reflected
wave of the ultrasonic wave transmitted from the transmitting unit 2 In any orientation.
[0060]
Third Embodiment FIG. 7 is a schematic view showing the main configuration of a hybrid
ultrasonic probe according to a third embodiment of the present invention, and FIG. 8 is a
longitudinal sectional view taken along line VIII-VIII in FIG. It is.
[0061]
The hybrid ultrasonic probe according to the third embodiment has the same configuration as
that of the hybrid ultrasonic probe according to the first embodiment, but the central portion of
the transmitting unit 2, more specifically, the common portion of the transmitting unit 2 A
circular through hole 7 penetrating the transmission unit 2 (hybrid ultrasonic probe 1) in the
opposing direction of the ground electrode 21 and the drive electrode 24 is provided.
The through holes 7 are formed in the front-rear direction along the rotation axis of the casing 6.
[0062]
The hybrid ultrasonic probe 1 according to the third embodiment of the present invention can be
inserted through the through hole 7 for introduction of a tool related to surgery, attachment of
other devices, etc. Function can be provided.
The shape of the through hole 7 is not limited to a circle.
[0063]
About the part similar to Embodiment 1, the same code | symbol is attached | subjected and
detailed description is abbreviate | omitted.
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[0064]
Fourth Embodiment FIG. 9 is a schematic vertical sectional view showing the main configuration
of a hybrid ultrasonic probe according to a fourth embodiment of the present invention.
The hybrid ultrasonic probe 1 according to the fourth embodiment of the present invention has
the same configuration as that of the hybrid ultrasonic probe according to the first embodiment,
but from the transmitting unit 2 in front of the transmitting unit 2 The acoustic lens 8 which
controls the ultrasonic wave of this.
[0065]
The acoustic lens 8 is made of, for example, an epoxy resin or the like, and is configured to cover
the front surface of the transmission unit 2.
That is, the ultrasonic wave from the transmission unit 2 is configured to pass through the
acoustic lens 8. In addition, the acoustic lens 8 has a concave shape in a cross-sectional view in
the longitudinal direction (front-rear direction). However, the present invention is not limited to
this, and the acoustic lens 8 may be convex.
[0066]
When a voltage is applied to the transmission unit 2, the individual piezoelectric elements 23
vibrate and ultrasonic waves are emitted in a direction perpendicular to the surface direction of
the common ground electrode 21 (see FIG. 5) of the transmission unit 2. The emitted ultrasonic
waves are diffused or focused by the acoustic lens 8 when passing through the acoustic lens 8.
[0067]
About the part similar to Embodiment 1, the same code | symbol is attached | subjected and
detailed description is abbreviate | omitted.
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[0068]
Fifth Embodiment FIG. 10 is a schematic vertical sectional view showing the main configuration
of a hybrid ultrasonic probe according to a fifth embodiment of the present invention.
[0069]
The hybrid ultrasonic probe 1 according to the fifth embodiment of the present invention has the
same configuration as the hybrid ultrasonic probe 1 according to the first embodiment, but
differs in the configuration of the transmission unit 2.
The transmission unit 2 of the hybrid ultrasonic probe 1 according to the fifth embodiment of
the present invention has a convex curved surface for diffusing ultrasonic waves.
[0070]
For example, in the hybrid ultrasonic probe 1 according to the fifth embodiment of the present
invention, a portion occupied by the transmitting unit 2 in the hybrid ultrasonic probe 1 of the
first embodiment is a backing portion. Filled with 4
Therefore, the front end surface of the backing portion 4 is provided so as to be substantially
flush with the vibrating electrode 32 or the vibrating film 31 of the receiving portion 3, and the
front end surface of the backing portion 4 is convex toward the front. The mount 26 is fixed. The
mounting portion 26 is made of, for example, the same material as the backing portion 4.
[0071]
The curved front surface of the mounting base 26 is provided with, for example, a 1-3 composite
vibration element 25 of a spherical shell type having a predetermined curvature and
manufactured in a shape familiar to the front surface. A well-known technique is used for the
manufacture of the spherical shell type 1-3 composite vibration element 25, and thus the
detailed description of the manufacture of the spherical shell type 1-3 composite vibration
element 25 is omitted. Further, the present invention is not limited to the 1-3 composite vibration
element 25 and may be a piezoelectric ceramic element such as a ZnO2 single crystal or a
04-05-2019
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diaphram thin film piezoelectric element (PZT thin film).
[0072]
A common ground electrode 21 having a curvature equal to that of the spherical shell type 1-3
composite vibration element 25 is provided on the front surface of the 1-3 composite vibration
element 25 so as to cover the front surface of the 1-3 composite vibration element 25 .
Therefore, the transmission unit 2 is provided to have a convex curved surface toward the object.
[0073]
When a voltage is applied to the transmitter 2, the ultrasonic wave emitted toward the front of
the hybrid ultrasonic probe 1 has a convex curved surface as described above for the common
ground electrode 21 of the transmitter 2. Because it has a fan shape, it spreads to the object and
travels.
[0074]
About the part similar to Embodiment 1, the same code | symbol is attached | subjected and
detailed description is abbreviate | omitted.
[0075]
In each embodiment described above, although the structure which arranged the transmission
part 2 in the center part of the hybrid ultrasound probe 1 was demonstrated as an example, it
does not restrict to this.
[0076]
DESCRIPTION OF SYMBOLS 1 hybrid type | mold ultrasound probe 2 transmission part 3
receiving part 4 backing part 5 insulation part 6 casing 7 through hole 8 acoustic lens 10 array
21 common ground electrode 22 filler 23 piezoelectric element 24 drive electrode 25 1-3
composite vibration element (Piezoelectric Vibrating Element) 26 Mounting Base 31 Vibrating
Film 32 Vibrating Electrode (First Electrode Plate) 33 Counter Electrode (Second Electrode Plate)
34 Substrate 35 Element Vibrating Element 61 Opening
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