JPH0345250

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DESCRIPTION JPH0345250
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic probe, and is particularly useful as a broadband probe of an ultrasonic diagnostic
apparatus. [Prior Art] An example of a conventional ultrasonic probe used in an ultrasonic
diagnostic apparatus is shown in FIG. The ultrasonic probe 101 includes a single-row type
piezoelectric vibrator element 102 in which a large number of piezoelectric vibrators in which
electrodes 107 and 107 are formed on both surfaces of a piezoelectric material piece 108 are
arranged in a single line. A first acoustic matching layer 105 and a second acoustic matching
layer 106 are provided on the transmission / reception side, and a backing material 103 is
provided on the opposite side. Power supply or power reception is performed for each of the
electrodes of each piezoelectric vibrator. [Problems to be Solved by the Invention] In the
conventional ultrasonic probe, the width of the ultrasonic pulse can not be sufficiently narrowed
due to the limitation of the bandwidth. For example, when used as a probe of an ultrasonic
diagnostic apparatus, the resolution is too high. There were problems that could not be done.
SUMMARY OF THE INVENTION An object of the present invention is to provide an ultrasonic
probe which has wide band characteristics and can transmit and receive ultrasonic pulses having
a sufficiently narrow width. [Means for Solving the Problems] In the ultrasonic probe according
to the present invention, an acoustically insulating surface is superposed on both sides of a bandshaped giant magnetostrictive material layer, and a conductor layer is further superposed on the
both surfaces, One end side of the conductor layer is connected to each other, and a band
member having a multilayer structure in which an electrically insulating layer is stacked on both
sides of the conductor layer is wound spirally, and power is supplied or received from the other
end side of the conductor layer This embodiment is characterized by having a high-winding
magnetostrictive transducer element. Further, according to another aspect, in the ultrasonic
probe according to the present invention, the acoustic insulating layer is superposed on both
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sides of the giant magnetostrictive material layer in the form of a piece, and the conductor layers
are further superposed on both sides thereof. A large number of strip members having a
multilayer structure in which one end sides of the layers are connected to each other and further
electrically insulating layers are stacked on both sides of the conductor layer are arranged in a
row, and power feeding or receiving is performed from the other end side of each conductor
layer. The constructional feature is that the single-row magnetostrictive transducer element as
described above is provided. According to still another aspect, the ultrasonic probe according to
the present invention is an arrayed magnetostrictive transducer element in which a large number
of magnetostrictive vibrators in which coils are attached around giant magnetostrictive material
pieces are one-dimensionally or two-dimensionally arrayed. The configurational feature is that
the device is provided. According to still another aspect, in the ultrasonic probe according to the
present invention, the conductor layer, the acoustic insulating layer, the giant magnetostrictive
material layer, and the acoustic insulating layer are repeatedly arranged in this order, and A
conductive layer is provided on one end side of each of the conductive layers, and a laminated
magnetostrictive vibrator element is provided to supply or receive power from the other end
side. .
In the two-leg configuration, a rare earth-iron alloy or an iron-based amorphous ferromagnetic
material can be used as the "gigantic release material". [Function co-conventional ultrasonic
probe uses PZT ceramics as a piezoelectric material. In this case, the value of the
electromechanical coupling coefficient of the transducer is 0. About seven is "one limit". In
general, the larger the electromechanical coupling coefficient k, the less energy can be retained
in the vibrator during electro-mechanical (acoustic) energy conversion, and as a result, the
frequency can be expanded, so that the vibration of the ultrasonic probe If the electromechanical
coupling coefficient k of the element can be made larger than 0.7, the characteristics are
improved. In the ultrasonic probe according to the present invention, the giant magnetostrictive
material layer is used to constitute the vibrator, but the electromechanical coupling coefficient k
can be increased to 0.75 to 0.96 by this giant magnetostrictive material. Sound energy can be
reduced in the vibrator during energy conversion, resulting in a wide band. Therefore, it becomes
possible to transmit and receive a narrow ultrasonic pulse, for example, to improve the resolution
in the ultrasonic diagnostic apparatus. Further, in the case of using a spiral magnetostrictive
transducer element, the required amplitude can be easily obtained by the width of the strip
member. Further, the required vibration area can be easily obtained by the length of the strip-like
member. Therefore, it becomes very easy to manufacture. In addition, in the case of using a
magnetostrictive vibrator element or a laminated magnetostrictive vibrator element, since it is
sufficient to stack the layers, this also becomes easy to be non- 'and +: t'. Furthermore, electronic
focusing and electronic scanning become possible. Furthermore, in the case of using an array
type magnetostrictive transducer element, a two-dimensional array can be configured. The
present invention will be described in more detail by way of embodiments shown in the
drawings. The present invention is not limited by this. The ultrasonic probe 1 shown in FIG. 1
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comprises a spiral magnetostrictive transducer element 2, a backing material 3, a magnetic shield
layer 4, a first acoustic matching layer 5, and a second acoustic matching layer 6. It has become.
As shown in FIG. 2, the spiral magnetostrictive transducer element 2 is formed by stacking a
plurality of thin strips of iron-based amorphous ferromagnetic material such as Fes + B + g, ssi
8.5C2, FevaSi, or B, 2 as shown in FIG. The giant magnetostrictive material layer 11, the acoustic
insulating layer 12 made of silicone rubber, the conductor layer 13.13 made of copper foil, and
the electrically insulating layer 14 made of silicone rubber are superposed, and one end of the
conductor layer 13.13 As shown in FIG. 3, the multi-layered strip members 10 connected to each
other on the side are spirally wound.
The backing material 3 is a ferrite rubber magnet, and has a function of applying a bias magnetic
field to the biped spiral magnetostrictive transducer element 2 together with the function of
acoustic insulation. By this bias magnetic field, positive and negative displacements can be
generated according to the feed current. The magnetic shield layer 4 is a thin film of permalloy,
amorphous magnetic material, electromagnetic soft iron or the like, and also has the function of
an earth plate and the function of an acoustic matching layer. The acoustic matching layer 5.6
consists of glass and plastic, respectively. In this ultrasonic probe, when a current pulse having a
waveform as shown by the solid line in FIG. 4 (a) is fed from the other end side of the conductor
layer 13.13, the giant magnetostrictive material layer 11 becomes as shown in FIG. 4 (b). The
ultrasonic pulse of the sound pressure waveform as shown by the solid line is sent out. When a
current pulse having a waveform as shown by a broken line in FIG. 4 (a) is given, an ultrasonic
pulse having a sound pressure waveform as shown by a broken line in FIG. 4 (b) results in
deformation in the negative sound pressure direction. In such a case, the giant magnetostrictive
material layer 11 may cause 7-brittle fracture, which is not preferable. At the time of reception,
the reception signal can be received from the other end side of the conductor layer 13.13
contrary to the above. In the ultrasonic probe 1, the electromechanical coupling coefficient k in
the giant magnetostrictive material layer 11 is 0.75 to 0.98, the energy conversion efficiency is
improved compared to the conventional case, and the wide area (1: · · · local resident becomes).
Next, FIG. 5 shows an ultrasonic probe 21 according to another embodiment of the present
invention. In this ultrasonic probe 21, a negative magnetostrictive transducer element 22 is used
in place of the spiral magnetostrictive transducer element 2 of the above embodiment. This
negative magnetostrictive vibrator element 22 is formed by winding the strip member 10 shown
in FIG. 2 in a square spiral shape, and cutting out a portion in which the sides are in parallel. The
conductor layers 13.13 are connected to each other at one end. The other end sides of the pair of
conductor layers 13.13 connected at one end side are respectively connected to the wide-band
boost matching transformer 27 so that they can be connected to a coaxial cable from an external
device. As the equivalent circuit is shown in FIG. 6, since each giant magnetostrictive material
layer 11 can operate independently, electronic focusing and electronic scanning can be
performed. Next, FIG. 7 shows an ultrasonic probe 31 according to still another embodiment of
the present invention. In the ultrasonic probe 31, the magnetic shield layer is omitted. In the
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magnetostrictive vibrator element 32, thin wires are arranged on both sides of the giant
magnetostrictive material layer 11 to form conductor layers 33, 33, and 33.
Are formed and filled with silicone rubber to form the insulating layer 12. Next, FIG. 8 shows an
ultrasonic probe 41 according to still another embodiment of the present invention. In this
ultrasonic probe 41, a giant magnetostrictive material piece 45 obtained by bundling fine
magnetostrictive material thin wires is crimped to the low melting point glass plate of the first
acoustic matching layer 44 in the heat process, and the coil 46 is fitted thereto. The silicon
rubber 47 is filled and integrated to form an array type magnetostrictive transducer element 42.
Next, ferrite rubber or tungsten epoxy is injected or pressed in a non-cured or semi-cured state to
form a backing tI3, and finally the second acoustic matching layer 6 is attached. This ultrasonic
probe 41 can be one-dimensional array as well as the ultrasonic probe 21.31 of the above
embodiment, but two-dimensional array is also possible. Next, FIG. 9 shows an ultrasonic probe
51 according to still another embodiment of the present invention. In the ultrasonic probe 51,
the conductor layer 53, the acoustic insulating layer 54, the giant magnetostrictive material layer
55, and the acoustic insulating layer 56 are repeatedly arranged in this order in a large number,
and finally the conductor layer 53 is provided. A laminated magnetostrictive transducer element
of a laminated structure in which the outside of the circle is covered with an electrically
insulating layer 57 is used. Conductor layers 53 and 53 as shown in FIG. Are all commonly
connected at one end side, and the other end side is each conductor layer 53.53. The voltage
boosting matching transformers 58 are respectively connected between. When power is supplied
to only one boosting matching transformer 58, the conductor layers 53 and 53 on both sides of
the boosting matching transformer 58 are provided. Current flows in the opposite direction to
each. At this time, if the primary sides of the other boosting matching transformers 58 are shortcircuited and the impedance of the secondary side of each boosting matching transformer 58 is
made 0, the giant magnetostrictive material layer 55 corresponding to the feeding of the
boosting matching transformers 58. In this case, the magnetic fields due to the currents flowing
through the conductor layers 53.53 on both sides thereof are added, but the others are canceled
out, so that only one giant magnetostrictive material layer 55 can be selectively operated.
However, even if the primary side of the boost matching transformer 58 is shorted, if the
impedance on the secondary side is not O or the primary side is open, the current becomes larger
as it approaches the fed boost matching transformer 58. A magnetic field as shown by a broken
line in FIG. 11 is formed, and an effect equivalent to operating only the giant magnetostrictive
material layer 55 corresponding to the feeding of the boosting matching transformer 58 and
reducing its width can be obtained.
[Effect of the Invention] = 11 According to the ultrasonic probe of the present invention, the
electromechanical coupling coefficient k can be increased to 0.75 to 0.96 because the vibrator is
configured using the giant magnetostrictive material layer. For this reason, the energy retained in
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the vibrator at the time of the electrical mechanical (acoustic) energy conversion can be reduced,
which results in a wide band. Therefore, the width of the ultrasonic pulse can be reduced and the
resolution can be improved.
[0002]
Brief description of the drawings
[0003]
1 is a cross-sectional view of an ultrasonic probe according to an embodiment of the present
invention, FIG. 2 is an external view including a partially enlarged view of a strip member, and
FIG. 3 is a partially cutaway perspective view of a spiral magnetostrictive transducer element
Figure 4, Figure 4 (a) is a waveform diagram of the feed current, Figure 4 (b) is a sound pressure
waveform diagram of the ultrasonic pulse, Figure 5 is a cross section of the ultrasonic probe of
another embodiment of the present invention FIG. 6 is an equivalent circuit diagram of the
ultrasonic probe shown in FIG. 5, FIG. 7 is a cross-sectional view of an ultrasonic probe according
to still another embodiment of the present invention, and FIG. Furthermore, a cross-sectional
view of an ultrasonic probe according to another embodiment, FIG. 9 is a cross-sectional view of
an ultrasonic probe according to still another embodiment of the present invention, and FIG. 12
is an ultrasonic wave shown in FIG. An equivalent circuit diagram of the probe, FIG. 11 is an
explanatory view of a magnetic field due to a feeding current in the ultrasonic probe shown in
FIG. 9, and FIG. 12 is a sectional view of an example of a conventional ultrasonic probe. .
(Explanation of the code) 1.21, 31, 41.51 ... ultrasonic probe 2 ... spiral magnetostrictive
transducer element 10 ... strip member 11 ... giant magnetostrictive material layer 12 ...
Acoustical insulating layer 13 ··· Conductor layer 14 · · · Electrical insulating layer 22.32 · · ·
Magnetostrictive vibrator element 42 of array type · · · Magnetostrictive element of array type 52
· · · Layered magnetostrictive vibration Child element.
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