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DESCRIPTION JP2000321254

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DESCRIPTION JP2000321254
[0001]
The present invention relates to an acoustic intensity distribution measuring apparatus used to
evaluate the performance of an apparatus using ultrasonic waves, such as an ultrasonic
diagnostic apparatus, in which the sound axis of the ultrasonic transducer is directed to the
measuring surface. The present invention relates to an adjustment method for making it
substantially vertical.
[0002]
2. Description of the Related Art Today, there is an apparatus such as an ultrasonic endoscope
and an ultrasonic diagnostic apparatus which uses an ultrasonic transducer and uses ultrasonic
waves emitted from the ultrasonic transducer (hereinafter referred to as an ultrasonic apparatus).
It has been put to practical use. When using this ultrasonic device, it is necessary to grasp the
acoustic intensity distribution because the performance such as the resolution of the ultrasonic
device is determined by the acoustic intensity distribution at a predetermined distance from the
ultrasonic transducer. .
[0003]
As an apparatus for measuring an acoustic intensity distribution (hereinafter referred to as an
acoustic intensity distribution measuring apparatus), an ultrasonic sensor for receiving an
ultrasonic wave emitted from an ultrasonic transducer, and the ultrasonic sensor as well as the
ultrasonic wave Sensor holding means capable of moving on the measurement surface separated
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by a predetermined distance from the vibrator, vibrator holding means for holding the ultrasonic
vibrator, and super rays emitted from the ultrasonic vibrator at each position on the
measurement surface There is a device provided with an acoustic intensity distribution
acquisition means for acquiring an acoustic intensity distribution of an ultrasonic transducer
based on an amplitude of an electric signal obtained by receiving a sound wave with an
ultrasonic sensor.
[0004]
When measuring the acoustic intensity distribution, the ultrasonic wave on the measurement
plane substantially perpendicular to the sound axis of the ultrasonic transducer (the axis at which
the ultrasonic intensity is maximum and generally corresponds to the vertical axis of the
transmission surface) It is necessary to measure the intensity.
On the other hand, in the conventional acoustic intensity distribution measuring apparatus, since
the measurement surface is a fixed surface, the holding angle of the ultrasonic transducer is
required to make the sound axis of the ultrasonic transducer perpendicular to the measurement
surface. Adjustment, so-called sound axis adjustment is required.
[0005]
Conventionally, as a method of adjusting the sound axis, for example, there has been a method of
adjusting while visually confirming the angle of the transmission surface of the ultrasonic
transducer with respect to the measurement surface. There is also a method of correcting the
sound axis offset amount by data processing (numerical calculation) without particularly
adjusting the sound axis at the time of measurement.
[0006]
However, for example, since the ultrasonic transducer in the ultrasonic probe is covered by the
sheath and is difficult to see, the position and angle of the ultrasonic transducer can not be
accurately grasped, so that the visual observation can not be performed. In the method of
adjusting while confirming in the above, there is a possibility that the sound axis may be inclined
even after the adjustment, and it has been difficult to measure the acoustic intensity distribution
accurately.
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[0007]
Further, even in the method of correcting by data processing, for the same reason, the
displacement amount of the sound axis can not be accurately grasped, a calculation error occurs,
and an accurate acoustic intensity distribution can not be grasped. The problem is that it takes
time for
[0008]
The present invention has been made in view of the above circumstances, and it is an object of
the present invention to provide a sound axis adjustment method capable of adjusting the sound
axis of an ultrasonic transducer accurately and in a short time when measuring an acoustic
intensity distribution. It is said that.
[0009]
In the sound axis adjustment method according to the present invention, ultrasonic intensity is
maximized by moving an ultrasonic sensor on a virtual plane close to an ultrasonic transducer
and parallel to a measurement surface at the time of normal measurement. At a predetermined
position (a position on a second virtual plane) at which the peak point is detected parallel to the
axis perpendicular to the measurement plane and away from the ultrasonic transducer. The angle
of the ultrasonic transducer is adjusted so that the intensity of the ultrasonic wave reaches a
maximum value, and the sound axis is adjusted by repeating this.
That is, according to the sound axis adjustment method of the present invention, the ultrasonic
sensor is movable on the measurement surface at a position separated by a predetermined
distance from the ultrasonic transducer, and the measurement surface centered on the sound
axis of the ultrasonic transducer is measured. In an acoustic intensity distribution measuring
device for measuring an acoustic intensity distribution of an ultrasonic transducer centered on a
sound axis by receiving an ultrasonic wave emitted from an ultrasonic transducer at each
position of An adjustment method for making a sound axis substantially perpendicular to a
measurement surface, which is parallel to the measurement surface and on one virtual plane
(first virtual plane) relatively short in distance from the ultrasonic transducer. The first step of
measuring the intensity of the ultrasonic wave emitted from the ultrasonic transducer at each
position of to detect the peak point where the intensity of the ultrasonic wave in the virtual plane
is maximum, and from the detected peak point Hanging on the measurement surface Measuring
the intensity of the ultrasonic wave emitted from the ultrasonic transducer at a desired point
(point on the second virtual plane) moved so that the distance from the ultrasonic transducer is
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relatively large in the direction The second step of adjusting the angle of the ultrasonic
transducer so that the intensity reaches the maximum value, and is parallel to the measurement
surface and is closer to the ultrasonic transducer than a desired point in the second step A sound
axis is made to converge so as to be perpendicular to the measurement surface by repeating a
cycle consisting of the first step and the second step with a plane having a relatively small
distance as a first virtual plane. It is said that.
[0010]
Here, "the angle of the ultrasonic transducer" means an angle with respect to the measurement
surface of the transmission surface of the ultrasonic transducer.
[0011]
The measurement plane was moved parallel to the axis perpendicular to the measurement plane,
that is, an axis formed by connecting a number of peak points at which the ultrasonic intensity of
the plane parallel to the measurement plane is maximum is the sound axis. When the axis
connecting the peak points becomes equal to the axis perpendicular to the measurement surface,
it can be judged as converged.
Specifically, when it is not necessary to change the angle of the ultrasonic transducer when the
intensity of the ultrasonic wave is measured at the desired point where the peak point detected in
the first step is moved in the second step, Alternatively, it can be determined that the peak point
detected in the first step of the next cycle after the angle adjustment in the second step has
converged when it is equal to the desired point of the second step in the previous cycle.
[0012]
To increase the convergence speed, it is preferable to increase the difference in distance from the
ultrasonic transducer in both steps.
[0013]
When the first step and the second step are repeated, a plane which is at least parallel to the
measurement surface and whose distance from the ultrasonic transducer is relatively smaller
than the desired point in the second step is the first The distance from the ultrasonic transducer
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of the first plane of the first cycle and the distance from the ultrasonic transducer of the first
plane of the next cycle may be different as long as it is repeated as a virtual plane. .
Similarly, the distance from the ultrasonic transducer at the desired point of the first cycle and
the distance from the ultrasonic transducer at the desired point of the next cycle may be
different.
[0014]
In addition, the distance from the ultrasonic transducer to the first virtual plane (first step) and
the distance from the ultrasonic transducer to the desired point (second step) have the relative
magnitude relationship as described above. Any size may be used, and either one may be the
same as the distance from the ultrasonic transducer to the measurement surface.
[0015]
According to the sound axis adjustment method of the present invention, the ultrasonic intensity
is moved by moving the ultrasonic sensor in the same manner as a normal measurement on a
virtual plane close to the ultrasonic transducer and parallel to the measurement surface.
Ultrasonic waves at a predetermined point at which the peak point of the peak point is detected,
and then the peak point is moved parallel to an axis perpendicular to the measurement plane and
relatively long distance from the ultrasonic transducer. The angle of the ultrasonic transducer is
adjusted so that the intensity of the peak reaches a peak, and this is repeated, so the angle
between the axis perpendicular to the measurement surface and the sound axis of the ultrasonic
transducer, that is, the sound axis The deviation angle of the angle gradually decreases with each
adjustment, and finally the axis perpendicular to the measurement surface and the sound axis
become parallel, and as a result, the sound axis of the ultrasonic transducer relative to the
measurement surface It will be possible to make it approximately vertical.
[0016]
Also, although the details will be described later, regardless of the mounting position and
mounting angle of the ultrasonic transducer, the axis perpendicular to the measurement surface
and the sound axis can be accurately converged in parallel, and after adjustment, the sound axis
becomes Since there is no risk of tilting, the acoustic intensity distribution can be measured
accurately.
[0017]
In addition, when detecting the peak point of the intensity in the above-mentioned adjustment
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step, since it is possible to use the same method as the normal measurement method of acoustic
intensity distribution, adjustment can be performed easily and in a short time.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described in detail below with reference to the drawings.
[0019]
FIG. 1 is a schematic block diagram of an acoustic intensity distribution measuring apparatus to
which the sound axis adjustment method according to the present invention is applied.
The ultrasonic device 50 to be measured includes an ultrasonic probe 51 and an ultrasonic
transmitter 52 that sends an electric signal for driving the ultrasonic probe 51.
An ultrasonic transducer 53 is provided in the distal end portion 51 a of the ultrasonic probe 51.
[0020]
The acoustic intensity distribution measuring apparatus 10 shown in FIG. 1 uses a hydrophone
11 as an ultrasonic sensor, and is set so that the ultrasonic transducer 53 and the hydrophone
11 are located in water, and the acoustic intensity distribution is underwater. It measures with.
That is, the acoustic intensity distribution measuring apparatus 10 includes a water tank 12 in
which water 13 is contained.
[0021]
A fixed leg 14 is provided around the water tank 12, and an L-shaped vibrator fixing portion 20
is positioned on one side 14 a of the fixed leg 14 so that an L-shaped tip portion 20 a is
positioned above the water 13. It is fixed.
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[0022]
A tilt stage 21 and a rotation stage 22 are provided at the tip 20a of the vibrator fixing portion
20, and the vibrator fixing arm 23 is attached such that the tip 23a of the vibrator fixing arm 23
is immersed in the water 13 .
The distal end portion 51 a of the ultrasonic probe 51 is held by the distal end portion 23 a of
the vibrator fixing arm 23 such that the ultrasonic transducer 53 in the distal end portion 51 a of
the ultrasonic probe 51 is positioned in the water 13.
[0023]
The tilt stage 21 and the rotation stage 22 can adjust the direction of the tip 51a of the
ultrasonic probe 51 held by the tip 23a of the vibrator fixing arm 23 with respect to the
hydrophone 11, As such, the direction (angle) of the transmission surface of the ultrasonic
transducer 53 with respect to the hydrophone 11 can be adjusted.
[0024]
On the other hand, on the other side 14 b of the fixed leg 14, an XYZ robot 30 consisting of an
XY table 31, a vertical axis 32 and a Z axis arm 33 is fixed so that the XY table 31 extends to the
top of the water 13 There is.
A vertical axis 32 is provided on the XY table 31 so as to be movable on the XY table 31.
The movable surface of the XY table 31 is taken as an XY plane.
A Z-axis arm 33 is attached to the vertical axis 32 so as to be movable in the axial direction of the
vertical axis 32, that is, the direction perpendicular to the XY plane.
A hydrophone fixing portion 34 is provided at the tip end portion 33a of the Z-axis arm 33, the
hydrophone fixing portion 34 is immersed in the water 13, and the hydrophone 11 is attached to
the hydrophone fixing portion 34. .
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[0025]
Drive motors 35x and 35y are provided on the XY table 31, and a drive motor 35z is provided on
the upper portion 32a of the vertical shaft 32.
A controller 36 is connected to these drive motors 35x, 35y, and 35z, and a drive current is
supplied from the controller 36 to the drive motor 35x so that the vertical axis 32 is in the X axis
direction of the XY plane (horizontal direction in FIG. In the same manner, the vertical axis 32 is
moved in the Y-axis direction (the depth direction in the drawing) perpendicular to the X-axis of
the XY plane by supplying the drive current to the drive motor 35y. Further, by supplying a drive
current to the drive motor 35z, the Z-axis arm 33 moves in the Z-axis direction (vertical direction
in the figure) orthogonal to the X-axis and the Y-axis. That is, the XYZ-axis robot 30 moves the
hydrophone 11 attached to the hydrophone fixing portion 34 provided at the distal end portion
33a of the Z-axis arm 33 in three axial directions of X axis, Y axis and Z axis orthogonal to each
other. It is configured to be able to move.
[0026]
As a result, the hydrophone 11 is set to an arbitrary distance with respect to the ultrasonic
transducer 53 in the distal end portion 51a of the ultrasonic probe 51, and the YZ plane
including the Y axis and the Z axis is used as a scanning surface (moving surface). The ultrasonic
wave emitted from the ultrasonic transducer 53 can be received at each position on the YZ plane
centered on the sound axis of the ultrasonic transducer 53 by the hydrophone 11 moving on the
YZ plane. It is supposed to be. The output signal of the hydrophone 11 obtained by receiving the
ultrasonic waves is input to the ultrasonic receiver 16 via the cable 15.
[0027]
The ultrasonic transmitter 52, the ultrasonic receiver 17 and the controller 36 are connected to a
system control device 17 such as a personal computer. The system control device 17 issues
commands to the ultrasonic transmitter 52 and the like to control the operation of the device,
and the electric signal sent from the hydrophone 11 and the position of the hydrophone 11 on
the YZ plane The sound intensity distribution of the ultrasonic transducer 53 is also acquired by
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processing in a corresponding manner.
[0028]
Next, a method of adjusting the sound axis of the ultrasonic transducer 53 in the acoustic
intensity distribution measuring apparatus 10 configured as described above will be described
with reference to FIGS. 2 is a three-dimensional view of the sound axis adjustment method
according to the present invention, FIG. 3 is a two-dimensional view of the sound axis adjustment
method according to the present invention, and FIG. 4 is a transmitter of the ultrasonic
transducer angle adjustment. It is a figure explaining movement.
[0029]
First, the hydrophone 11 is set in the water 13 by the XYZ-axis robot 30 at a predetermined
distance from the tip 51 a of the ultrasonic probe 51. Specifically, as shown in FIG. 2, the
hydrophone 11 is disposed at an arbitrary position on the A plane, assuming that the YZ plane at
the point of X coordinate is x1 is a virtual measurement plane (hereinafter referred to as the A
plane).
[0030]
Next, an electric signal is sent from the ultrasonic transmitter 52 to the ultrasonic transducer 53
for driving, and ultrasonic waves are emitted from the ultrasonic transducer 53 into the water
13.
[0031]
The radiated ultrasonic waves propagate in the water 13 to reach the hydrophone 11, are
received by the hydrophone 11, and are converted into electrical signals.
The electric signal is subjected to processing such as delay synthesis in the ultrasonic receiver
16, converted into a reception signal of an amplitude level corresponding to the intensity of the
ultrasonic wave received by the hydrophone 11, and sent to the system control device 17.
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[0032]
And while emitting an ultrasonic wave from the ultrasonic transducer 53, while changing the
position of the hydrophone 11 on the A plane, which is a virtual measurement surface, as in the
case of measuring the normal acoustic intensity distribution by the XYZ axis robot 30. The
intensity of the ultrasonic wave emitted from the ultrasonic transducer 53 is measured at each
position in the same manner as described above (while scanning), and the peak point of the
intensity is detected (corresponding to the first step of the present invention). That is, by plotting
the relationship between each position on the A plane of the hydrophone 11 and the amplitude
of the reception signal, the acoustic intensity distribution of the ultrasonic transducer 53 on the
A plane is determined, and as a result, the peak point of the intensity To detect. This peak point is
shown as "1" in FIG. 2 and FIG.
[0033]
Next, the detected peak point 1 is made parallel to the axis (X axis) perpendicular to the
measurement plane, and the distance from the ultrasonic transducer 53 is relatively larger than
the position on the above-mentioned A plane. The hydrophone 11 is moved to a point (indicated
as "2" in the figure) on the B plane, where the YZ plane moved at a point of X coordinate x2 is a
virtual measurement plane (hereinafter referred to as a B plane). Then, at this point 2, the
intensity of the ultrasonic wave emitted from the ultrasonic transducer 53 is measured, and the
angle of the ultrasonic transducer 53 is determined by the tilt stage 21 and the rotation stage 22
so that the intensity reaches a peak. (Corresponding to the second step according to the present
invention). By this angle adjustment, the sound axis before adjustment is in the direction
indicated by “a” in the drawing, and the direction indicated by “b” closer to parallel to the X
axis is obtained. Here, even if the rotation center at the time of angle adjustment adjusts the
angle of the transmitting unit 53a, that is, the ultrasonic transducer 53, the position of the
transmitting unit 53a is shown as being unchanged.
[0034]
Next, the hydrophone 11 is moved to the surface A, and the peak point of the ultrasonic intensity
is detected on the surface A in the same manner as described above. This peak point is a point on
the axis "b" which is closer to the X axis than the axis "a", and hence is a point indicated by "3" in
the figure.
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[0035]
Thereafter, by repeating the same process as described above, the sound axis of the ultrasonic
transducer 53 is gradually made parallel to the X axis as indicated by “a”, “b” and “c” in
the figure. Converge on
[0036]
FIG. 3 is shown in two dimensions of the X-axis and the Z-axis to explain this process of
convergence in more detail.
In FIG. 3, an angle of the sound axis in the direction a with respect to the X axis is θa. This θa
represents the first shift angle of the sound axis.
[0037]
The A plane is disposed at the position x1 on the X axis where the transmission unit 53a of the
ultrasonic transducer 53 is at the origin 0, and the B plane is disposed at the position x2 further
away. x1 represents the distance from the transmission unit 53a to the A plane, and x2
represents the distance from the transmission unit 53a to the B plane (x1 <x2). By the adjustment
described above, the directions of the sound axes are changed to b, c, and d, and the angles that
each forms with the X axis are θb, θc, and θd.
[0038]
Since the distance on the Z1 axis of the peak point "1" of the ultrasonic intensity on the A plane
and the distance on the Z2 axis of the peak point "2" of the ultrasonic intensity on the B plane are
the same, x1 · tan θa From = x 2 · tan θ b, tan θ b = (x 1 / x 2) · tan θ a. Similarly, tan θc = (x1
/ x2) · tan θb = (x1 / x2) 2 · tan θa tan θd = (x1 / x2) · tan θc = (x1 / x2) 3 · tan θa
[0039]
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That is, assuming that one cycle consisting of the first and second steps in the adjustment
method described above is repeated n times, the deviation angle θ n of the sound axis after
adjustment is θ n = tan −1 {(x1 / x2 Can be expressed as n n · tan θ a}, and the deviation angle
θ n gradually approaches 0. That is, the sound axis converges to be parallel to the X axis.
[0040]
In addition, the difference of the distance from the ultrasonic transducer | vibrator 53 is large,
and as (x1 / x2) is small, it converges with few frequency | counts. Specifically, the surface A is
disposed in the vicinity of the ultrasonic transducer 53 (xa → 0), and the surface B is disposed at
a long distance (xb → ∞), and convergence is performed less frequently.
[0041]
Since the X axis is an axis perpendicular to the measurement plane at a predetermined position
on the X coordinate where the original acoustic intensity distribution is to be measured, the
sound axis is parallel to the X axis as described above (in this example If the acoustic intensity
distribution is measured after convergence to the X axis itself, the peak point of the intensity is
on the X axis perpendicular to the measurement surface, and accurate measurement can be
performed. Will be able to
[0042]
In addition, the peak of the ultrasonic intensity can be detected by substantially the same
measurement method as in the case of measuring a normal acoustic intensity distribution only by
changing the measurement distance on the X axis from the ultrasonic transducer, and the
adjustment operation can be performed. It can be done simply and quickly.
[0043]
The above description has been described on the assumption that the position of the transmitting
unit 53a does not change even if the angle of the ultrasonic transducer 53 is adjusted. The
attachment position and attachment angle of the sound wave vibrator 53 can not always be
grasped accurately.
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Therefore, when the direction of the distal end 51a is adjusted by the tilt stage 21 and the rotary
stage 22, the distal end 51a of the ultrasonic probe 51 at the distal end 23a of the transducer
fixing arm 23 rotates around the transmitter 53a. It is difficult to hold
In this case, the movement of the transmission unit 53a at the time of angle adjustment is as
shown in FIG. That is, angle adjustment is performed with the position O different from that of
the transmission unit 53a as the rotation center. Therefore, every time the sound axis is adjusted
to a, b, c, the position of the transmitting unit 53a also changes. However, even if the position of
the transmitting unit 53a changes in this manner, the adjustment method according to the
present invention does not change the fact that the sound axis gradually converges so as to be
parallel to the X axis.
[0044]
Therefore, if the acoustic intensity distribution is measured after the acoustic axis converges
parallel to the X axis as described above, the peak point of the intensity is on the axis parallel to
the X axis perpendicular to the measurement plane The sound axis can be made substantially
perpendicular to the measurement surface regardless of the position of the rotation center at the
time of angle adjustment, and the acoustic intensity distribution can be measured accurately. .
[0045]
In the above description, the adjustment is performed by moving the hydrophone, which is
usually used at the time of measurement, to the A side and the B side using the XYZ-axis robot,
but the invention is not limited thereto. A sensor capable of receiving an ultrasonic wave emitted
from a transducer may be disposed at a desired position on each surface.
[0046]
Further, in the above description, the peak point on the A plane where the intensity of the
ultrasonic wave emitted from the ultrasonic transducer is maximum is determined, and the peak
point is moved away from the ultrasonic transducer on the B plane The sound axis is adjusted by
repeating the adjustment of the angle of the ultrasonic transducer so that the intensity of the
ultrasonic wave emitted from the ultrasonic transducer reaches a maximum value at the point of
The invention is not limited to this.
That is, when repeating one cycle consisting of the first step and the second step, a plane which
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is at least parallel to the measurement surface and whose distance from the ultrasonic transducer
is relatively smaller than the desired point in the second step is The distance from the ultrasonic
transducer of the first plane of the first cycle and the distance from the ultrasonic transducer of
the first plane of the next cycle may be used as long as they repeat as a virtual plane, and the
desired value of the first cycle The distance from the ultrasonic transducer at the point of and the
distance from the ultrasonic transducer at the desired point of the next cycle may be respectively
different, and the newly set new plane is taken from each of the following cycles Both steps
described above may be repeated as the A side or the B side.
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