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DESCRIPTION JP2003175036

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DESCRIPTION JP2003175036
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
ultrasonic probe and an ultrasonic diagnostic apparatus, and more particularly to an ultrasonic
probe and an ultrasonic diagnostic apparatus provided with an acoustic velocity control element.
[0002]
2. Description of the Related Art In ultrasonic diagnosis, an ultrasonic probe is brought into
contact with the surface of a living body, and in that state, transmission and reception of
ultrasonic waves are performed. Japanese Patent Application Laid-Open No. 11-123188
discloses a new type of ultrasonic probe having a sound velocity control element. In such an
ultrasonic probe, a sound velocity control element is provided on the upper surface of the
vibrating element that transmits and receives ultrasonic waves, and one or more matching layers
(matching elements) are provided on the upper surface thereof.
[0003]
The sound velocity control element is made of, for example, a piezoelectric material like the
vibrating element, and the characteristics of the sound velocity control element are changed by
changing the electrical impedance of the external circuit connected to the sound velocity control
element. It is possible to adjust the degree of control action.
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[0004]
On the other hand, 1.5D array vibrators (or 1.25D array vibrators) are conventionally known.
This array transducer basically performs the electronic scanning of the ultrasonic beam in the
same manner as the 1D array transducer, and the electronic focusing or the transmitting /
receiving aperture of the ultrasonic wave also in the elevation direction orthogonal to the
electronic scanning direction. For example, five or seven vibration elements are arranged along
the elevation direction so that variable control can be performed. By performing electronic
control of transmission and reception timing in the elevation direction, it is possible to control
the focusing of the ultrasonic beam in the elevation direction.
[0005]
While the focusing action of the acoustic lens is fixed (fixed focus), the 1.5D array transducer has
an advantage that the focus can be changed electronically.
[0006]
SUMMARY OF THE INVENTION In the 1.5D array vibrator as described above, if the abovementioned sound velocity control element is used, as described in detail in the above-mentioned
publication, the number of cables and the transmission and reception of the main body of the
device The advantage of being able to reduce the number of circuits can be obtained.
However, in general, the sound velocity control range (so-called delay amount) by the sound
velocity control element having a normal size is not very large, and the sound velocity control
element alone can obtain satisfactory ultrasound beam focusing in the elevation direction. There
is a problem that you can not Further, if the thickness of the sound velocity control element or
the like is increased to increase the sound velocity control range, manufacture becomes difficult,
and the influence of the ultrasonic wave attenuation in the inside can not be ignored, which
causes a problem.
[0007]
The present invention has been made in view of the above-described conventional problems, and
an object thereof is to reduce the number of transmission / reception circuits without
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significantly increasing the number of cables without significantly increasing the number of
cables. It is possible to electronically change the ultrasonic beam pattern in the longitudinal
direction.
[0008]
SUMMARY OF THE INVENTION (1) In order to achieve the above object, according to the present
invention, a plurality of transducer elements aligned in the electronic scanning direction, and
each transducer element are provided on the living body side for passage. A plurality of sound
velocity control elements having characteristics of adjusting the sound velocity of the ultrasonic
waves, and a plurality of sound velocity control elements provided on the living body side of the
plurality of sound velocity control elements across them, the ultrasonic waves in the elevation
direction orthogonal to the electronic scanning direction And an acoustic lens for focusing,
wherein each of the sound velocity control elements comprises a plurality of sound velocity
control element elements aligned in the elevation direction.
[0009]
According to the above configuration, it is possible to change the focusing of the ultrasonic beam
fixedly obtained by the acoustic lens by adjusting the sound velocity control action of the
plurality of sound velocity control element elements aligned in the elevation direction.
For example, it becomes possible to make the actual focus point shallower or deeper (or
displaced laterally) with respect to the fixed focus point by the acoustic lens, that is, it becomes
possible to freely adjust the beam pattern.
[0010]
Moreover, there is an advantage that it is not necessary to significantly increase the number of
signal lines and the number of transmission / reception circuits of the device body for such
electronic control.
That is, the present invention combines the fixed beam pattern adjustment operation by the
acoustic lens and the variable beam pattern adjustment operation by the sound velocity control
element group, and according to the present invention, from the shallow portion to the deep
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portion Since good resolution can be obtained, the image quality of the entire ultrasound image
can be improved. The above configuration may be used to correct the phase disturbance in the
elevation direction.
[0011]
In the above configuration, a convex lens is generally used as the acoustic lens, but a concave
lens may be used. The circuit for adjusting the operating characteristics of each sound velocity
control element may be provided in the ultrasonic probe or may be provided in the ultrasonic
diagnostic apparatus main body. Examples of the material constituting the sound velocity control
element include piezoelectric ceramic, piezoelectric single crystal, composite piezoelectric
material, piezoelectric polymer material and the like.
[0012]
Further, the present invention can be applied to various ultrasonic probes such as a linear array
type, a convex array type, and a sector array type.
[0013]
Preferably, the plurality of sound velocity control element elements constituting each of the
sound velocity control elements include a center sound velocity control element element and a
plurality of side sound velocity control element elements provided symmetrically on both sides
thereof.
Here, a relatively large (long in the direction of elevation) may be used as the center sound
velocity control element, and a relatively small (short in the direction of elevation) may be used
as the side sound velocity control element. According to this configuration, the ultrasonic wave
passage time can be adjusted more finely near both ends in the elevation direction. The sizes of
the plurality of side sound velocity control elements may be the same or may be gradually
reduced toward the end.
[0014]
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Preferably, an acoustic gap is formed between the plurality of sound velocity control element
elements constituting each of the sound velocity control elements. According to this
configuration, it is possible to prevent mutual adverse effects between the sound velocity control
element elements such as the wraparound of ultrasonic waves.
[0015]
Preferably, a plurality of matching elements are provided between the plurality of sound velocity
control elements and the acoustic lens, and each of the matching elements comprises a plurality
of matching element elements provided for each of the respective sound velocity control element
elements. Preferably, an acoustic gap is formed between the plurality of matching element
elements constituting each of the matching elements. As described above, when the matching
element element is provided for each sound velocity control element element and acoustically
separated from each other, the wraparound of the ultrasonic wave can be prevented.
[0016]
(2) In addition, in order to achieve the above object, according to the present invention, in an
ultrasonic diagnostic apparatus including an ultrasonic probe and an apparatus main body, the
ultrasonic probes are arranged in a plurality of electronic scanning directions. A vibration
element, a plurality of sound velocity control elements provided on the living body side for each
of the vibration elements and having characteristics of adjusting the sound speed of passing
ultrasonic waves, and a living body side of the plurality of sound velocity control elements And
an acoustic lens for focusing an ultrasonic wave in an elevation direction orthogonal to the
electronic scanning direction, wherein each of the speed control elements comprises a plurality
of speed control elements aligned in the elevation direction, The apparatus main body includes a
control unit for controlling the characteristics of each of the sound velocity control element
elements, and the control unit controls the characteristics of the respective sound velocity
control element elements to control the ultrasonic wave in the elevation direction. Characterized
by varying the beam pattern.
[0017]
According to the above configuration, with respect to the plurality of sound velocity control
element elements aligned in the elevation direction, the sound velocity of the passing ultrasonic
waves is individually controlled to thereby transmit and receive the ultrasonic waves in each
sound velocity control element element. The delay time can be set, and as a result, the beam
pattern can be manipulated in the elevation direction.
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[0018]
Desirably, a signal lead is provided on the lower surface side of each vibration element, and a
ground lead is provided on the upper surface side of each vibration element (between the
plurality of vibration elements and the plurality of sound velocity control elements) .
As described above, each sound velocity control element is composed of a plurality of sound
velocity control element elements (sound velocity control element element “row”) aligned in
the elevation direction, and the plurality of sound velocity control elements are in the electronic
scanning direction (array direction) As a whole, a plurality of sound velocity control element
elements constitute a two-dimensional array.
Viewed another way, the two-dimensional array aligns a plurality of sound velocity control
element element groups (sound velocity control element elements “row”) consisting of a
plurality of sound velocity control element elements aligned in the electronic scanning direction
in the elevation direction Corresponds to the Then, sound speed control leads are provided as
electrodes for each sound speed control element group. According to such a configuration, it is
sufficient to provide the sound velocity control lead for each sound velocity control element
group on the premise that the plurality of ground leads function as a common ground. The
number of lines and the increase in control circuits can be avoided, and the manufacturing cost
can be reduced.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present
invention will be described below with reference to the drawings.
[0020]
FIG. 1 is a perspective view showing an essential part of an ultrasonic probe according to the
present invention.
In FIG. 1, various leads are not shown.
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[0021]
In FIG. 1, the vibrating element array 10 is configured by a plurality of vibrating elements 12
arranged in the electronic scanning direction (array direction) as the X direction. Grooves 22 as
acoustic gaps are formed between the respective transducer elements 12. Fillers 22 with acoustic
isolation function are filled in the grooves 22 as needed. Each vibration element 12 operates
individually, and the configuration itself is known. On the lower surface side of the vibrating
element array 10, a backing 14 that absorbs the ultrasonic wave emitted to the rear surface side
is provided.
[0022]
The sound velocity control element array 16 is provided on the upper surface side of the
vibration element array 10 in the present embodiment. The sound velocity control element array
16 is constituted by a plurality of sound velocity control elements 18 aligned in the array
direction, and each sound velocity control element 18 is constituted by a plurality of elements
18A to 18E aligned in the elevation direction as the Y direction. Here, as illustrated, the centrally
located element 18C has a relatively large form in the elevation direction, and the plurality of
elements 18A, 18B, 18D, 18E disposed on both sides thereof are larger than the element 18C. It
has a short width. In FIG. 1, each sound velocity control element 18 is constituted by five
elements 18A to 18E, but of course it is an example, and the number thereof is selected
according to the fineness of the delay of the passing ultrasonic wave in the elevation direction,
etc. It may be selected as appropriate. Each of the elements 18A to 18E independently has a
function of changing the speed of sound of ultrasonic waves passing therethrough. Specifically,
as will be described later with reference to FIG. 3, by changing the electrical impedance in the
variable impedance circuit connected to each element 18A to 18E, the elements 18A to 18E
connected to that circuit The acoustic characteristics can be varied, and as a result, it is possible
to adjust the speed of sound of ultrasonic waves passing through the elements 18A to 18E.
[0023]
Incidentally, each sound velocity control element 18 is made of, for example, a piezoelectric
ceramic, a piezoelectric single crystal, a composite piezoelectric material, a piezoelectric polymer
material, or the like. Incidentally, as shown in FIG. 1, a groove 20 is formed as an acoustic gap
between the respective elements 18A to 18E, and in the groove 20, a filler having an acoustic
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isolation property is provided. Be filled. That is, similar to the groove 22 described above, the
groove 20 is for preventing acoustic wrap around.
[0024]
As understood from the above description, in the vibrating element array 10, the elements 18A
to 18E having the sound velocity control function constitute a two-dimensional array, ie, an
element composed of a plurality of elements aligned in the elevation direction A plurality of
columns are aligned in the electronic scanning direction, in other words, a plurality of element
groups (element rows) composed of a plurality of elements aligned in the electronic scanning
direction are aligned in the elevation direction.
[0025]
A first matching element array 30 and a second matching element array 32 are provided on the
upper surface side of the sound velocity control element array 16.
The first matching element array 30 is constituted by a plurality of first matching elements 34 as
shown, and similarly, the second matching element array 32 is also constituted by a plurality of
second matching elements 36. The first matching element 34 and the second matching element
36 are each divided into a plurality of elements, ie, the first matching element 34 is divided into a
plurality of elements 34A to 34E, and the second matching element 36 is a plurality of elements.
It is divided into elements 36A to 36E. The elements 34A to 34E and 36A to 36E are provided for
each of the elements 18A to 18E, that is, the arrangement of the elements 18A to 18E matches
the arrangement of the elements 34A to 34E and 36A to 36E. That is, in the same manner as the
acoustic wrap around in the sound velocity control element array 16 is prevented, the acoustic
wrap around is also prevented in the first matching element array 30 and the second matching
element array 32. By the way, grooves 35, 37 are formed between the elements 34A to 34E, 36A
to 36E, and the grooves 35, 37 have fillings with acoustic isolation as described above. Be filled.
Of course, gaps are formed above the grooves 22 between the sound velocity control elements
18, between the first matching elements 34, and between the second matching elements 36. The
agent is filled. However, in place of such filler filling of the grooves and gaps, they may be used
as air gaps.
[0026]
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On the upper surface side of the second matching element array 32, an acoustic lens 40 having a
bulged central portion with a wedge shape as illustrated is provided. As described above, the
acoustic lens 40 has a convex shape, but the acoustic lens may have a concave shape. As well
known, the acoustic lens 40 has a function to adjust the beam pattern in the elevation direction,
but itself is a fixed adjustment function, for example, to change the focal point along the depth
direction. Can not. In the present embodiment, as described above, the elements 18A to 18E of
the plurality of sound velocity control elements 18 having the function of controlling the sound
velocity are provided in alignment in the elevation direction. Temporal delay control in the
elevation direction can be performed on the ultrasonic waves, and as a result, like the acoustic
lens 40, adjustment of the beam pattern in the elevation direction can be electronically
performed. That is, the beam pattern fixedly set by such an additive action is corrected. Although
the above description relates to the propagation of ultrasonic waves at the time of transmission,
the beam pattern is similarly adjusted at the time of reception.
[0027]
Incidentally, for adjustment of the beam pattern in the electronic scanning direction, an
electronic focusing technique is applied as in the prior art. The present invention can be applied
to ultrasonic probes having various forms such as a linear array, a convex array or a sector array.
[0028]
FIG. 2 shows various electrodes or leads which are not shown in FIG.
[0029]
Signal leads 42 are provided on the lower surface side of the transducer array 10 for each
transducer 12.
Further, ground leads 44 are provided for each of the vibration elements 12. In the example
shown in FIG. 2, the ground leads 44 constitute an array, but it is also possible to constitute the
ground leads 44 by so-called solid electrodes. Here, the ground lead 44 functions as a common
ground for the vibration element array 10 and the sound velocity control element array 16.
Further, as shown in FIG. 2, on the upper surface side of the sound velocity control element array
16, the sound velocity control lead is provided for each element group including a plurality of
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elements (sound velocity control element elements) aligned in the array direction (electronic
scanning direction). 46 are provided. That is, as described above, each sound velocity control
element 18 is divided into, for example, five in the elevation direction, and, for example, five
sound velocity control leads 46 are provided corresponding to the divided sections. Here,
focusing on one sound velocity control lead 46, it is provided across elements at the same
position in the elevation direction in each sound velocity control element 18.
[0030]
According to the configuration as shown in FIG. 2, in the vibration element array 10, each signal
is aligned with the array direction by individually supplying the transmission signal to the signal
lead 42 or processing the reception signal individually. The elements 12 can be operated
independently. At the same time, in the sound velocity control element array 16, the electrical
impedance of the sound velocity control lead 46 is varied for each of the above element groups
to individually control the sound velocity of the ultrasonic waves passing through them. It
becomes possible. Therefore, compared to the number of signal lines in the case where an
ultrasonic beam is scanned two-dimensionally by forming a so-called two-dimensional array
transducer, according to the above embodiment, the number of signal lines as a whole ultrasonic
probe is The effect is that the number can be significantly reduced. Since the number of signal
lines can be reduced, the size of the circuit for generating each signal and the circuit for
processing can be reduced, and the manufacturing cost can be significantly reduced.
[0031]
Incidentally, in the above embodiment, the size in the X direction of each transducer in the
transducer array 10 is, for example, 0.2 mm, the size in the Y direction is, for example, 10 mm,
and the thickness in the Z direction of each transducer 12 Is, for example, 0.5 mm. The thickness
in the Z direction of each sound velocity control element 18 is, for example, 1 mm.
[0032]
In the above embodiment, two matching element arrays are provided in an overlapping manner
in order to further improve the matching of the acoustic impedance between the vibrating
element array 10 and the living body, but of course only one matching element array It may be
provided.
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[0033]
Although the vibrating element array 10 in FIG. 1 is configured of, for example, 128 vibrating
elements 18, the number of the vibrating element arrays 10 can be appropriately selected
according to the diagnostic application and the like.
Incidentally, the width of the groove 22 is, for example, 0.04 mm, and the width of the grooves
20, 35, 37 is, for example, 0.04 mm.
[0034]
FIG. 3 shows a schematic configuration of the ultrasonic diagnostic apparatus according to the
present invention as a conceptual diagram. This ultrasonic diagnostic apparatus is roughly
divided into an apparatus main body 49 and an ultrasonic probe 51.
[0035]
In the ultrasonic probe 51, in the example shown in FIG. 3, the variable impedance circuit 50 is
provided for each sound velocity control element group aligned in the elevation direction, that is,
a circuit for forming an electrical impedance is provided. ing. The electrical impedance is
controlled by a control circuit 54 provided in the device body 49. Incidentally, the control circuit
54 is provided for each variable impedance circuit 50, and the transmission / reception circuit
52 is provided for each vibration element 12. Those transmission / reception circuits 52 and
their control circuits 54 are controlled by a controller not shown.
[0036]
FIGS. 4 and 5 conceptually show the actions of the respective elements 18A to 18E constituting
the sound velocity control element 18, and FIG. 4 shows a case where an acoustic focus point is
set at a short distance. FIG. 5 shows the case where an acoustic focus point is set at a long
distance. Incidentally, the beam pattern shown by the broken line in each figure is by the
acoustic lens 40 alone, and the beam pattern by the solid line shows the pattern formed using
the sound velocity control element 18 in addition thereto. As shown in FIG. 4, when performing
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measurement at a short distance, the largest value is set at the central part in the elevation
direction as the delay amount of the ultrasonic wave, and the delay amount decreases gradually
from there to the left and right ends It is set. According to such a delay amount distribution, it is
also possible to set the actual focus point F1 on the side shallower than the focus point F2
formed by the acoustic lens 40 alone.
[0037]
Further, as shown in FIG. 5, when setting the focus point at a long distance, the amount of delay
in the central portion in the elevation direction is also reduced as shown, and the amount of
delay gradually increases from that point to the left and right ends. It is set to be large. As a
result, as shown in the drawing, it is possible to set the actual focus point F1 at a position deeper
than the focus point F2 of the acoustic lens 40 alone.
[0038]
Even when the sound velocity control shown in FIGS. 4 and 5 is performed, as shown in FIG. 2, it
is only necessary to vary the electrical impedance connected to the sound velocity control lead
46 provided for each element group. The simple circuit configuration has the advantage that the
image quality of the ultrasound image can be improved over the entire range from the shallow
area to the deep area. Although FIG. 4 and FIG. 5 show the control in the depth direction of the
focus point, the focus point may be shifted in the horizontal direction, that is, the elevation
direction if necessary, and further transmission and reception in the elevation direction The size
of the opening may be limited. Furthermore, it is also possible to adjust the beam pattern shape
while maintaining the focus point. In addition, the disturbance of the phase between a center part
and an edge part etc. can also be suppressed by said sound speed control.
[0039]
FIG. 6 shows a method of manufacturing the ultrasound probe according to the present
embodiment as a flowchart. In S101, the plurality of signal leads 42 and the backing 14 are
attached to the lower surface side of the flat piezoelectric member, and the plurality of ground
leads 44 and the flat sound velocity control member are attached to the upper surface of the flat
piezoelectric member. . In S102, cutting along the elevation direction is performed on the
assembly configured in S101, and the groove 22 created thereby is filled with a filler.
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[0040]
In S103, the plurality of sound velocity control leads 46 and the first alignment member and the
second alignment member are attached to the assembly. Then, in S104, cutting along the array
direction is performed on the assembly configured in S103. Furthermore, cutting along the
elevation direction of the first and second acoustic matching members is performed at the same
interval as the cutting performed in S102. In this cutting, the second acoustic matching member
is not completely cut so as not to cut the sound velocity control lead 46, leaving a non-cut
portion of a slight thickness. The grooves formed by these are filled with a filler.
[0041]
And an acoustic lens will be stuck in S105 after that. The plurality of signal leads 42 may be
configured by a so-called flexible circuit board (FPC), and the same applies to the plurality of
ground leads 44 and the sound velocity control leads 46.
[0042]
As described above, according to the present invention, the ultrasonic beam pattern in the
elevation direction can be electronically adjusted without causing a significant increase in the
number of cables.
[0043]
Brief description of the drawings
[0044]
FIG. 1 is a perspective view showing an essential configuration of an ultrasonic probe according
to an embodiment of the present invention.
[0045]
2 is an explanatory diagram for explaining the arrangement of the leads.
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[0046]
FIG. 3 is a conceptual view showing an entire configuration of an ultrasonic diagnostic apparatus
according to the present embodiment.
[0047]
FIG. 4 is a diagram showing a delay amount distribution when a focus point is set at a short
distance.
[0048]
FIG. 5 is a diagram showing a delay amount distribution when the focus point is set at a long
distance.
[0049]
6 is a flowchart showing a method of manufacturing an ultrasound probe.
[0050]
Explanation of sign
[0051]
DESCRIPTION OF SYMBOLS 10 vibration element array, 12 vibration element, 14 backing, 16
sound velocity control element array, 18 sound velocity control element, 30 first matching
element array, 32 second matching element array, 34 first matching element, 36 second
matching element, 42 Signal lead, 44 ground leads, 46 sound velocity control leads.
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