U.S. patent application number 12/606608 was filed with the patent office on 2010-04-29 for apparatus and method for ultrasonic testing.
This patent application is currently assigned to HITACHI, LTD.. Invention is credited to Atsushi BABA, So KITAZAWA, Naoyuki KONO.
Application Number | 20100106431 12/606608 |
Document ID | / |
Family ID | 42044425 |
Filed Date | 2010-04-29 |
United States Patent
Application |
20100106431 |
Kind Code |
A1 |
BABA; Atsushi ; et
al. |
April 29, 2010 |
APPARATUS AND METHOD FOR ULTRASONIC TESTING
Abstract
An apparatus and a method for ultrasonic testing obtains
high-resolution and high-S/N ratio testing results by driving a
number of piezoelectric elements using fewer pulsers and receivers
in comparison with the number of elements composing an array
transducer. A sensor information setter sets a plurality of
piezoelectric element groups used for transmission and a plurality
of piezoelectric element groups used for reception among the
plurality of piezoelectric elements composing an ultrasonic array
transducer. A computer transmits an ultrasonic wave from the
element cluster set for transmission, and stores an ultrasonic wave
received by the element cluster set for reception. The procedure is
repeated including different element cluster sets for transmission
and reception to obtain first receive signals. The first receive
signals are summed to obtain a second receive signal; and the
second receive signal is displayed with reference to the sensor
center position on a display unit.
Inventors: |
BABA; Atsushi; (Tokai,
JP) ; KITAZAWA; So; (Mito, JP) ; KONO;
Naoyuki; (Mito, JP) |
Correspondence
Address: |
MATTINGLY & MALUR, P.C.
1800 DIAGONAL ROAD, SUITE 370
ALEXANDRIA
VA
22314
US
|
Assignee: |
HITACHI, LTD.
Tokyo
JP
|
Family ID: |
42044425 |
Appl. No.: |
12/606608 |
Filed: |
October 27, 2009 |
Current U.S.
Class: |
702/39 |
Current CPC
Class: |
G01N 29/04 20130101;
G01S 15/8925 20130101; G01S 15/8993 20130101; G01S 15/8918
20130101; G01S 15/8927 20130101; G01N 29/07 20130101; G01S 15/8997
20130101; G01N 2291/106 20130101; G01N 29/2468 20130101; G01N
29/262 20130101 |
Class at
Publication: |
702/39 |
International
Class: |
G01N 29/04 20060101
G01N029/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 29, 2008 |
JP |
2008-278038 |
Oct 29, 2008 |
JP |
2008-278053 |
Feb 26, 2009 |
JP |
2009-043586 |
Claims
1. An ultrasonic testing apparatus for testing the inside of an
object under test by transmitting an ultrasonic wave to the object
under test and receiving reflected waves (echoes) from the surface
or inside thereof by using an ultrasonic array transducer composed
of a plurality of one- or two-dimensionally arranged piezoelectric
elements, the ultrasonic testing apparatus comprising: sensor
information setting means configured to set a plurality of element
groups (element clusters) to be used for transmission and reception
out of the plurality of piezoelectric elements composing the
ultrasonic array transducer; transmission selection means
configured to select an element cluster used for transmission out
of the set plurality of element clusters; reception selection means
configured to select an element cluster used for reception out of
the set plurality of element clusters; delay time control means
configured to give a delay time to each of the piezoelectric
elements used for transmission and piezoelectric elements used for
reception with reference to a sensor center position serving as a
reference for the delay time; a computer configured to obtain a
second receive signal by performing the steps of: transmitting an
ultrasonic wave from the element cluster set for transmission, and
storing an ultrasonic wave received by the element cluster set for
reception as a first receive signal; repeating a procedure for
changing the element cluster set for transmission and the element
cluster set for reception and storing another first receive signal;
and summing up the plurality of first receive signals obtained by
repeating the same procedure; and display means configured to
display the second receive signal with reference to the sensor
center position.
2. The ultrasonic testing apparatus according to claim 1, wherein
the computer sets a virtual array transducer and uses a center
position of the virtual array transducer as a sensor center
position or a reference for a delay time.
3. The ultrasonic testing apparatus according to claim 1, wherein
the computer selects a first or second set of element cluster
combinations; wherein the first set of element cluster combinations
used for transmission and reception includes combinations in which
an element cluster used for transmission is identical to an element
cluster used for reception; and wherein the second set of element
cluster combinations used for transmission and reception includes
combinations in which an element cluster used for transmission is
different from an element cluster used for reception.
4. An ultrasonic testing method for testing the inside of an object
under test by transmitting an ultrasonic wave to the object under
test and receiving reflected waves (echoes) from the surface or
inside thereof by using an ultrasonic array transducer composed of
a plurality of one- or two-dimensionally arranged piezoelectric
elements, the ultrasonic testing method comprising the steps of:
setting a plurality of element groups (element clusters) for
transmission and reception out of a plurality of piezoelectric
elements composing the ultrasonic array transducer; selecting an
element cluster used for transmission out of the set plurality of
element clusters, and selecting an element cluster used for
reception out of the set plurality of element clusters; giving a
delay time to each of the piezoelectric elements used for
transmission and/or the piezoelectric elements used for reception
with reference to a sensor center position serving as a reference
for the delay time; transmitting an ultrasonic wave from the
element cluster set for transmission, and storing an ultrasonic
wave received by the element cluster set for reception as a first
receive signal; repeating a procedure for changing the element
cluster set for transmission and the element cluster set for
reception and storing another first receive signal; summing up the
plurality of first receive signals obtained by repeating the same
procedure to obtain a second receive signal; and displaying the
second receive signal with reference to the sensor center
position.
5. The ultrasonic testing method according to claim 4, wherein the
method sets a virtual array transducer and uses a center position
of the virtual array transducer as a sensor center position or a
reference for a delay time.
6. The ultrasonic testing method according to claim 4, wherein the
method selects a first or second set of element cluster
combinations; wherein the first set of element cluster combinations
used for transmission and reception includes combinations in which
an element cluster used for transmission is identical to an element
cluster used for reception; and wherein the second set of element
cluster combinations used for transmission and reception includes
combinations in which an element cluster used for transmission is
different from an element cluster used for reception.
7. A method for three-dimensional ultrasonic imaging comprising the
steps of: transmitting an ultrasonic wave from a two-dimensional
array ultrasonic sensor to focus at a desired depth;
three-dimensionally scanning the inside of an object under test
while varying the ultrasonic beam angle, and storing waveform data;
converting the obtained waveform data to three-dimensional testing
data; storing the three-dimensional testing data by sequentially
changing the set position of the array ultrasonic sensor; and
combining the three-dimensional testing data obtained at each
testing position while making a shift by the displacement of the
array ultrasonic sensor to attain three-dimensional imaging.
8. The three-dimensional ultrasonic imaging method according to
claim 7, comprising the steps of: measuring a surface shape of the
object under test, following the surface shape thereof, and storing
three-dimensional testing data of the inside of the object under
test while varying the ultrasonic beam angle; sequentially moving
the set position of the array ultrasonic sensor and testing the
object under test; and combining three-dimensional testing data
obtained at each testing position while making a shift by a
displacement and a rotation angle of the array ultrasonic sensor to
attain three-dimensional imaging.
9. The three-dimensional ultrasonic imaging method according to
claim 7, wherein the method changes the beam angle of the
ultrasonic wave transmitted from the two-dimensional array
ultrasonic sensor to select rotation scanning, swing scanning, or
wedged swing scanning as an ultrasonic scanning process for
three-dimensional testing of the inside of the object under
test.
10. The three-dimensional ultrasonic imaging method according to
claim 7, wherein the method combines three-dimensional testing data
by summing up (or averaging) three-dimensional testing data to
attain imaging.
11. A three-dimensional ultrasonic imaging apparatus comprising: a
two-dimensional array ultrasonic sensor composed of a plurality of
piezoelectric elements; pulsers configured to transmit a transmit
signal to each piezoelectric element of the array ultrasonic
sensor; receivers configured to receive a receive signal; delay
control means configured to perform time control for the transmit
and receive signals by varying a delay time for each piezoelectric
element; data storage means configured to store ultrasonic
waveforms transmitted and received by the array ultrasonic sensor;
sensor moving means configured to feed the array ultrasonic sensor,
and scanning control means configured to control the sensor moving
means; displacement detection means configured to measure the
displacement of the array ultrasonic sensor; a computer configured
to convert the stored waveform data to three-dimensional testing
data, and combine the plurality of pieces of three-dimensional
testing data while making a shift by the displacement of the array
ultrasonic sensor measured by the displacement detection means; and
display means configured to display the combined testing data.
12. The three-dimensional ultrasonic imaging apparatus according to
claim 11, further comprising: sensor moving means which moves the
sensor following a surface shape of the object under test, a
scanning controller, and displacement detection means; and a
computer which combines three-dimensional testing data while making
a shift by the displacement and angle of the array ultrasonic
sensor based on the detected displacement of the array ultrasonic
sensor and measurement value or design value of the surface shape
of the object under test.
13. The three-dimensional ultrasonic imaging apparatus according to
claim 11, wherein the display means includes data processing
switching means configured to switch between testing data obtained
by ordinary testing and testing data obtained by combining
processing; wherein, in ordinary testing, a maximum value out of
testing data sequentially obtained by moving the array ultrasonic
sensor is handled as testing data.
14. A three-dimensional ultrasonic testing apparatus comprising: an
ultrasonic sensor composed of a plurality of piezoelectric
elements; pulsers configured to supply a transmit signal to each
piezoelectric element of the ultrasonic sensor; receivers
configured to input a receive signal from each piezoelectric
element of the ultrasonic sensor; data storage means configured to
store ultrasonic waveforms received by the ultrasonic sensor; a
computer for image processing configured to generate
three-dimensional testing data from the waveforms stored in the
data storage means; and three-dimensional display means configured
to display the three-dimensional testing data generated by the
computer, wherein the computer outputs the distance between the two
points specified on the three-dimensional display means.
15. The three-dimensional ultrasonic testing apparatus according to
claim 14, wherein the computer displays three-dimensional shape
data superimposed with three-dimensional testing data on the
three-dimensional display means.
16. The three-dimensional ultrasonic testing apparatus according to
claim 14, the two points specified on the three-dimensional display
means constitute an echo caused by a reflected ultrasonic wave
signal on the three-dimensional testing data.
17. The three-dimensional ultrasonic testing apparatus according to
claim 16, wherein the points composing the echo caused by the
reflected ultrasonic wave signal is contained in a
three-dimensional region specified on the three-dimensional display
means, a signal value of the echo being maximized at the point.
18. The three-dimensional ultrasonic testing apparatus according to
claim 14, wherein one of the two points specified on the
three-dimensional display means is an ultrasonic incidence point or
the point constituting three-dimensional shape data.
19. The three-dimensional ultrasonic testing apparatus according to
claim 14, wherein the computer displays on the three-dimensional
display means a distance between the two points specified on the
three-dimensional display means
20. The three-dimensional ultrasonic testing apparatus according to
claim 14, wherein the computer displays on the three-dimensional
display means a straight line connecting the two points specified
on the three-dimensional display means.
21. The three-dimensional ultrasonic testing apparatus according to
claim 14, wherein the computer outputs a relative position of the
points specified on the three-dimensional display means relative to
an ultrasonic incidence point using an angle and a distance.
22. A three-dimensional ultrasonic testing method for testing the
inside of an object under test by transmitting an ultrasonic wave
to the object under test and receiving reflected waves therefrom by
using an ultrasonic sensor composed of a plurality of piezoelectric
elements, wherein the method measures a distance between two echoes
caused by a reflected ultrasonic wave signal based on a distance
between the two points specified on the three-dimensional display
means.
23. A three-dimensional ultrasonic testing method according to
claim 22, wherein, based on the points specified on the
three-dimensional display means, the method outputs a relative
position of the echoes caused by a reflected ultrasonic wave signal
relative to an ultrasonic incidence point using an angle and a
distance.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus and a method
for ultrasonic testing which is one of non-destructive testing
methods. More particularly, the present invention is related to an
apparatus and a method for ultrasonic testing by using an array
ultrasonic sensor.
[0003] 2. Description of the Related Art
[0004] Conventional ultrasonic testing methods targeting various
kinds of structural materials utilize an ultrasonic sensor composed
of a single element for transmission and reception of an ultrasonic
wave. The ultrasonic sensor receives an ultrasonic signal reflected
by a defect or the like inside an object under test to detect a
defect based on the propagation time of the ultrasonic signal and
the position of the ultrasonic sensor.
[0005] Specifically, conventional methods comprises the steps of:
appropriately selecting an angle and vibration mode (longitudinal
wave, transversal wave, etc.) of an ultrasonic wave to be applied
to the object under test; moving the ultrasonic sensor to obtain a
position at which a sufficiently strong reflected wave (echo) can
be obtained from a defect; and identifying the size of the defect
based on a difference between reception times of reflected waves
from the bottom surface (far-side boundary surface) and the top
face (near-side boundary surface) of the object under test,
multiplied by the sonic velocity of the material of the object
under test.
[0006] These methods are commonly used for ordinary defect
inspections because of their simple operating principle and
relatively simple instrumentation. However, since it is necessary
to measure a reflected ultrasonic wave and evaluate the existence
and position of a defect only from reception time of the reflected
wave, high-accuracy testing requires experienced inspector and is
time-consuming.
[0007] In recent years, new ultrasonic testing methods have been
developed. As represented by the phased array method, these new
techniques image the inside of an object under test with high
accuracy (refer to, for example, Nonpatent Document 1).
[0008] The phased array method utilizes a so-called ultrasonic
array transducer composed of an array of several tens of
piezoelectric elements and operates on a principle that wave fronts
of ultrasonic waves transmitted from the piezoelectric elements
mutually interfere to form one combined wave front in the course of
propagation. Therefore, controlling the timing of ultrasonic wave
transmission from each piezoelectric element with a time delay (on
a time-shift basis) makes it possible to control the ultrasonic
beam angle and allow the ultrasonic wave to focus.
[0009] When receiving reflected ultrasonic waves, summing up these
waves received by the piezoelectric elements on a time-shift basis
makes it possible to control the receive beam angle of one combined
ultrasonic wave as well as receive ultrasonic waves at one focal
position in a similar way to transmission.
[0010] Generally known processes for the phased array method
include the linear scanning process which linearly feeds
piezoelectric elements and the sectorial scanning process which
changes ultrasonic-wave transmit and receive directions in a
fan-like form. Both processes can apply ultrasonic waves at high
speed without moving the ultrasonic sensor and control the beam
angle and focal depth position of the ultrasonic wave without
replacing the ultrasonic sensor. Therefore, it can be said that
both techniques enable high-speed and high-accuracy testing.
[0011] Of the above-mentioned conventional techniques, the phased
array method has the advantage of controlling the beam angle and
focal position of the combined ultrasonic wave by using a plurality
of piezoelectric elements, and allowing high-speed and
high-accuracy testing.
[0012] On the other hand, the focal depth is determined by an
aperture of the array transducer (nearly equals the size of a
piezoelectric element composing the array transducer multiplied by
the number of elements). Therefore, testing an object having a long
propagation path therein or a thick plate requires a large-sized
array transducer (an array transducer composed of a number of
elements) having a focal depth suitable for its size.
[0013] For example, suppose a case where a steel material (with a
sonic velocity of longitudinal ultrasonic wave of 6000 m/s and a
wavelength of 3 mm) is tested by using an array transducer with a
frequency of 2 MHz. Generally, with an ultrasonic transducer having
an aperture size of A (mm), the ultrasonic wave is strong in the
vicinity of the near-sound-field limit distance (NF) represented by
the formula (1) below. Therefore, an ultrasonic transducer having a
larger aperture is required to test a thicker material. When using
an array transducer normally having a constant frequency and a
constant interval between piezoelectric elements, it is necessary
to use a multi-element array transducer having increased number of
piezoelectric elements for testing.
[Formula 1]
NF=A.sup.2/4.lamda. (1)
[0014] An ultrasonic testing apparatus employing a multi-element
array transducer needs to have pulser, receiver, and wiring
circuits corresponding to the total number of elements in order to
drive the multi-element array transducer. Accordingly, there has
been a problem that a remarkable increase in size and complexity in
internal structure and wiring causes degradation in portability,
installability, and maintainability.
[0015] In order to solve this problem, an imaging method using a
small number of pulsers and receivers corresponding to the number
of some elements of the ultrasonic array transducer, for example,
the synthetic aperture method is used (Nonpatent Document 2).
[0016] With the synthetic aperture method, a single ultrasonic
transducer having a small sensor aperture transmits an ultrasonic
wave so that it widely spreads out into an object under test, and
the same or different ultrasonic transducer receives a reflected
ultrasonic wave signal (echo) from the inside of the object.
[0017] The operating principle of the synthetic aperture method is
that, since the propagation path of ultrasonic wave is known, a
defect serving as a sound source of a received reflected ultrasonic
wave exists on a circular arc having the position of a
piezoelectric element which transmitted and received an ultrasonic
wave as a center and the propagation distance of the reflected
ultrasonic wave as a radius. (When different piezoelectric elements
are used for transmission and reception, a defect exists on an
ellipse arc having each of the piezoelectric element for
transmission and the piezoelectric element for reception as a focal
position.)
[0018] Based on this operating principle, the ultrasonic sensor
transmits and receives ultrasonic waves while sequentially changing
the position of an active ultrasonic transducer for transmission
and reception. At each transducer position, a receive signal is
spread out in a circular arc form (or in an ellipse arc form)
through computer operations. Then, intersections of these circular
arcs focus at one position where a defect exists (a true reflection
source position) thus allowing the defect position to be located
and imaged.f
[Nonpatent Document 1]
[0019] Yoshikazu Yokono, Global Trend of Phased Array Ultrasonic
Testing Its Practical Application and Standardization, The Japanese
Society for Non-destructive Inspection, Vol. 56, No. 10, 2007.
[Nonpatent Document 2]
[0020] Michimasa Kondo, Yoshimasa Ohashi, and Akio Jitsumori,
Digital Signal Processing Series Vol. 12, Digital Signal Processing
in Measurement and Sensors, pp. 143-186, May 20, 1993, SHOKODO CO.,
LTD.
[0021] A conventional method for testing a defect of an object
under test such as a structural material transmits an ultrasonic
wave by using a single ultrasonic sensor and receives echoes
reflected by a defect or the like inside the object under test by
using a single ultrasonic sensor to detect a defect based on the
propagation time of the ultrasonic wave and the position of the
ultrasonic sensor. The conventional method also moves the
ultrasonic sensor to obtain a position where a reflected echo from
a defect is obtained, and identifies the size of the defect based
on a difference between reception times of reflected echoes from
the bottom and surface, multiplied by the sonic velocity of the
material of the object under test. This method is commonly used for
ordinary defect inspections because of its simple operating
principle and relatively simple instrumentation. However, since it
is necessary to measure reflected ultrasonic echoes and evaluate
existence and position of a defect from the reception time of the
reflected echoes, high-accuracy testing requires experienced
inspector and is time-consuming.
[0022] In recent years, new ultrasonic testing methods have been
developed. As represented by well-known phased array method and
synthetic aperture focusing method, these new techniques image the
inside of an object under test with high accuracy. The phased array
method utilizes an array of a plurality of piezoelectric elements
and operates on a principle that wave fronts of ultrasonic signals
transmitted from the piezoelectric elements mutually interfere to
form one combined wave front in the course of propagation.
Therefore, controlling the timing of ultrasonic wave transmission
from each piezoelectric element with a time delay (on a time-shift
basis) makes it possible to control the ultrasonic beam angle and
allow ultrasonic wave to focus. When receiving reflected ultrasonic
waves, summing up these waves received by the piezoelectric
elements on a time-shift basis on the time axis makes it possible
to receive ultrasonic waves at one focal position in a similar way
to transmission. The phased array method makes it possible to apply
ultrasonic waves at high speed without moving the ultrasonic sensor
and control the beam angle and focus depth position of the
ultrasonic wave without replacing the ultrasonic sensor. Therefore,
it can be said that the phased array method enables high-speed and
high-accuracy testing. Generally known processes for the phased
array method include the linear scanning process which linearly
feeds piezoelectric elements and the sectorial scanning process
which changes ultrasonic-wave transmit and receive directions in a
fan-like form.
[0023] On the other hand, the synthetic aperture method transmits
an ultrasonic wave so that it widely spreads out into an object
under test, and receives a reflected ultrasonic signal from the
inside of the object. The operating principle of the synthetic
aperture method is that a defect serving as a sound source of the
received reflected ultrasonic wave exists on a circular arc having
the position of a piezoelectric element which transmitted and
received an ultrasonic wave as a center and the propagation
distance of the reflected ultrasonic wave as a radius. Based on
this operating principle, the ultrasonic sensor transmits and
receives ultrasonic waves while sequentially changing the position
of a piezoelectric element. At each vibrator position, a received
waveform is spread out in a circular arc form through computer
operations. Then, intersections of these circular arcs focus at one
position where a defect exists (an ultrasonic wave reflection
source) thus allowing the defect position to be located and imaged.
Actually, the synthetic aperture method performs high-resolution
imaging through computer operations using the position of the
ultrasonic sensor and the ultrasonic waveform signal at that
position. Details of computer operations are discussed in Nonpatent
Document 2.
[0024] In recent years, new sensors such as a matrix array
transducer and a ring array transducer have been developed. The
matrix array transducer is composed of an array of piezoelectric
elements arranged in a matrix pattern inside an array ultrasonic
sensor, and the ring array transducer is composed of an array of
coaxially arranged piezoelectric elements (including arrangements
in the circumferential direction). Further, apparatuses that can
transmit and receive ultrasonic waves by using a number of
piezoelectric elements have come into practical use. Thus, the
inside of an object under test directly under the ultrasonic sensor
can be three-dimensionally imaged without moving the ultrasonic
sensor. With a known method for three-dimensionally imaging the
inside of an object under test, a two-dimensional array ultrasonic
sensor transmits an ultrasonic wave sequentially from each element
and then receives a reflected ultrasonic wave with all elements
and, at the same time, three-dimensional aperture synthetic
processing is performed so as to superimpose received echoes (refer
to, for example, Patent Document 1).
[Patent Document 1]
[0025] JP-2005-315582-A
[Nonpatent Document 2]
[0026] Michimasa Kondo, Yoshimasa Ohashi, and Akio Jitsumori,
Digital Signal Processing Series Vol. 12, Digital Signal Processing
in Measurement and Sensors, pp. 143-186, May 20, 1993, SHOKODO CO.,
LTD.
[0027] In recent years, new ultrasonic testing methods targeting
various kinds of structural materials have been developed. As
represented by the phased array method, these new techniques image
and test the inside of an object under test with high accuracy in a
short time (refer to, for example, Nonpatent Document 3).
[0028] The phased array method utilizes an array of a plurality of
piezoelectric elements (also referred to as ultrasonic array
transducer) and operates on a principle that wave fronts of
ultrasonic waves transmitted from the piezoelectric elements
mutually interfere to form one combined wave front in the course of
propagation. Therefore, controlling the timing of ultrasonic wave
transmission from each piezoelectric element with a time delay (on
a time-shift basis) makes it possible to control the ultrasonic
beam angle and allow the ultrasonic wave to focus.
[0029] When receiving reflected ultrasonic waves, summing up these
waves received by the piezoelectric elements on a time-shift basis
in accordance with the delay time makes it possible to control the
receive beam angle of one combined ultrasonic wave as well as
receive ultrasonic waves at one focal position in a similar way to
transmission.
[0030] Generally known processes for the phased array method using
a one-dimensional array transducer having linearly arranged
piezoelectric elements include the linear scanning process which
scans in ultrasonic-wave transmit and receive directions together,
and the sectorial scanning process which changes ultrasonic-wave
transmit and receive directions in a fan-like form centering on an
incident point. Further, the use of a two-dimensional array
transducer having piezoelectric elements arranged in a lattice
pattern makes it possible to three-dimensionally focus on a desired
spatial position, allowing selection of a scanning process which
best suits the shape of the object under test. In particular, the
three-dimensional scanning technique makes it possible to apply
ultrasonic waves at high speed without moving the sensor, and
control the beam angle and focal depth position of the ultrasonic
wave, allowing high-speed and high-accuracy testing.
[0031] At present, in order to locate a spatial position of a
reflection source from reflected ultrasonic wave signals, a method
for presuming a spatial position from a plurality of
two-dimensional images of reflection strength distributions at
different cutting positions is commonly used (hereinafter this
method is referred to as two-dimensional phased array method). For
example, since the linear and sectorial scanning processes can
obtain a plurality of two-dimensional images corresponding to a
scanning range and interval, the direction in which a reflected
wave appears can be located by sequentially changing the images on
the display screen.
[0032] Recently, a new three-dimensional display method
(hereinafter referred to as three-dimensional ultrasonic testing
method) has been reported. This method performs interpolation
processing to reflected ultrasonic wave signals from a plurality of
directions to create three-dimensional lattice-like data and then
performs volume rendering and surface rendering techniques to the
created data. Although there are more than one method for creating
three-dimensional lattice-like data, for example, the synthetic
aperture method and phased array method, a method based on the
phased array method is particularly referred to as
three-dimensional phased array method (refer to, for example,
Nonpatent Document 2). As three-dimensional lattice-like data, a
data structure composed of a plurality of three-dimensionally
arranged cubic elements (referred to as voxels) is most widely used
because of ease of handling. This structure is also referred to as
structural lattice. Although a lattice having irregular spatial
lattice arrangements may be used in addition to voxels, such a
lattice is slightly more difficult to display than a voxel. This
kind of lattice is referred to as non-structural lattice as
represented by a six-face lattice, a four-face lattice, a
triangular pyramidal (prism) lattice, and a quadrangular pyramidal
(pyramid) lattice. Further, there is another method for displaying
data as three-dimensional point groups without conversion to
lattice-like data. Since these pieces of data are saved in computer
memory as three-dimensional testing data, they can be checked from
any desired direction by an inspector after measurement.
[0033] In recent years, flaw size measurement (sizing) using the
phased array method has attracted attention in industrial fields.
Particularly in the field of nuclear power, the phased array method
has been specified as a method for sizing a fatigue crack of carbon
steel and stainless steel and a crack height of a stress corrosion
crack (SCC) of stainless steel by technical guidance JEAC 4207-2004
of the Japan Electric Association which serves as an evaluation
criterion for the soundness of domestic light-water nuclear
reactors. At present, this guidance is taken over to technical
regulation JEAG4207-2008 of the Japan Electric Association. The
scope of the phased array method has been expanded not only as a
method for sizing crack height but also as a method for checking
the existence of a crack (refer to, for example, Nonpatent Document
4).
[0034] When measuring a flaw height (crack height), the
two-dimensional phased array method utilizes sectorial-scanned or
linear-scanned images including echoes at ends of a flaw. In this
case, measurement must be performed according to defined
measurement and analysis procedures, and it is recommended to
validate the procedures by using a test piece having a flaw. These
procedures are prescribed as flaw height measurement method based
on the tip echo technique by NDIS 2418 standard of the Japanese
Society for Non-destructive Inspection (refer to, for example,
Nonpatent Document 5).
[0035] However, with the two-dimensional phased array method,
echoes corresponding to upper and lower ends of a crack
(hereinafter referred respectively to upper- and lower-end echoes)
need to be included in the same screen. Therefore, it is necessary
to finely adjust the sensor position and the ultrasonic beam angle
depending on the orientation of a flaw. This method is
time-consuming and requires experience to a certain extent. If the
shape of the flaw is included in the same plane, it is preferable
to find and measure an image in which upper- and lower-end echoes
are clearly displayed in this way. However, if the shape of the
flaw is complicated with many branches, such as scc, the shape of
the flaw is not necessarily included in the same plane. In this
case, two or more images are needed to measure the flaw height
accuracy with the two-dimensional phased array method.
[0036] In this case, the use of the three-dimensional ultrasonic
testing method is very effective. Although there are not many cases
reported, a sizing method based on the three-dimensional ultrasonic
testing method has been devised. A method discussed in Nonpatent
Document 6 displays measurement data points obtained by a plurality
of tests on a screen as point groups. With a desired cross section
displayed, for example, when two points corresponding to upper- and
lower-end echoes are specified by using a mouse or keyboard of a
computer, the distance between the two points is output. With the
two-dimensional phased array method, it is necessary to find a
screen in which upper- and lower-end echoes are simultaneously
included at the time of data storage. With the three-dimensional
ultrasonic testing method, on the other hand, it is only necessary
to perform a series of data storage for a predetermined testing
range and then find a target cross section. The latter method makes
testing procedures very efficient and is advantageous.
[Nonpatent Document 3]
[0037] Yoshikazu Yokono, Global Trend of Phased Array Ultrasonic
Testing Its Practical Application and Standardization, The Japanese
Society for Non-destructive Inspection, Vol. 56, No. 10, (2007)
[Nonpatent Document 4]
[0038] Atsushi Baba, Satoshi Kitazawa, Naoyuki Kono, Yuji Adachi,
Mitsuru Odakura, and Osamu Kikuchi, Development of
Three-dimensional Ultrasonic Testing System 3D Focus-UT, JAPAN
SOCIETY OF MAINTENOLOGY, 5th Academic Lecture, Collection of
Summaries, 155 (2008)
[Nonpatent Document 5]
[0039] The Japanese Society for Non-destructive Inspection NDIS
2418:2005, pp. 21
[Nonpatent Document 6]
[0040] Potts, A.; McNab, A.; Reilly, D.; Toft, M., "Presentation
and analysis enhancements of the NDT Workbench a software package
for ultrasonic NDT data", REVIEW OF PROGRESS IN QUANTITATIVE
NONDESTRUCTIVE EVALUATION: Volume 19. AIP Conference Proceedings,
Volume 509, pp. 741-748 (2000).
SUMMARY OF THE INVENTION
[0041] However, the synthetic aperture method described in the
first background art has a problem that it is difficult to obtain a
receive signal having a sufficient S/N ratio. Since this method
uses a single ultrasonic transducer having a small sensor aperture,
applying it to a case with a long propagation distance of
ultrasonic wave disperses or attenuates the ultrasonic wave signal
resulting in a decrease in signal intensity.
[0042] A first object of the present invention is to provide an
apparatus and a method for ultrasonic testing which make it
possible to obtain high-resolution and high-S/N ratio testing
results through imaging by driving a number of piezoelectric
elements, the apparatus and method comprising less number of
pulsers and receivers in comparison with the number of elements
composing an array transducer.
[0043] With the second background art, it is necessary to store a
data processing table (focal law, delay time) corresponding to the
number of coordinate positions of three-dimensional testing data in
order to obtain focused three-dimensional testing data over the
entire three-dimensional space. Since the number of coordinate
positions is physically limited, there is a trade-off relation
between the size of a target region and the spatial resolution of
three-dimensional imaging. Therefore, in order to
three-dimensionally image a wide testing range with high
resolution, it is necessary to divide the testing range into a
plurality of test regions and repeat a sequence comprising reading
a data processing table, reconfiguring the table, and
measurement.
[0044] Although the second background art provides favorable
accuracy and sensitivity in imaging directly under a
two-dimensional array ultrasonic sensor, there has been a problem
that both accuracy and sensitivity fall in imaging at a position
not directly under the ultrasonic sensor. Therefore, for a wide
testing range, testing needs to be performed separately in a
plurality of steps to cover the entire testing range.
[0045] With the second background art, the two-dimensional array
ultrasonic sensor is composed of small-sized piezoelectric
elements, each providing weak ultrasonic transmission energy, and
the sensor transmits an ultrasonic wave with one element during
transmission. Therefore, the spatial energy of the ultrasonic wave
is weak. Also during reception, since the receive energy per
element is weak, the sensor is susceptible to noise including
electrical noise. This causes a problem that, with a thick object
and a high attenuation material, the echo intensity of the
ultrasonic wave decreases to degrade the S/N ratio of the received
echo.
[0046] A second object of the present invention is to provide an
apparatus and a method for ultrasonic imaging which enable
collective three-dimensional imaging over a wide testing range
based on high resolution and high S/N ratio three-dimensional
testing data and allow images to be handled as one piece of
three-dimensional testing data by using a two-dimensional array
ultrasonic sensor. The present embodiment only utilizes one set of
data processing table (focal law) and is also applicable to thick
objects and high-attenuation materials.
[0047] Further, with the defect sizing method based on conventional
three-dimensional ultrasonic testing methods described in the third
background art, it is difficult and time-consuming to a certain
extent to find and specify a cross section including upper- and
lower-end echoes on the screen. Further, in order to grasp which
cross section is currently being observed, it is necessary to
constantly monitor the three-dimensional display screen and the
cross-section screen for comparison. Further, in order to perform a
plurality of measurements in combination with echoes at different
positions, it is necessary to find a plurality of cross sections
corresponding to each combination. This causes a problem of
complicated procedures.
[0048] A third object of the present invention is to provide an
apparatus and a method for ultrasonic testing which enable
three-dimensional measurement of the distance between echoes in a
simple way in sizing a defect such as a crack.
[0049] In order to attain the above-mentioned first object, the
present invention provides an ultrasonic testing apparatus for
testing the inside of an object under test by transmitting an
ultrasonic wave to the object under test and receiving reflected
waves (echoes) from the surface or inside thereof by using an
ultrasonic array transducer composed of a plurality of one- or
two-dimensionally arranged piezoelectric elements. The ultrasonic
testing apparatus includes: a sensor information setting unit
configured to set a plurality of element groups (element clusters)
to be used for transmission and reception out of a plurality of
piezoelectric elements composing the ultrasonic array transducer; a
transmission selection unit configured to select an element cluster
for transmission out of the set plurality of element clusters; a
reception selection unit configured to select an element cluster
for reception out of the set plurality of element clusters; a delay
time control unit configured to give a delay time to each of the
piezoelectric elements for transmission and/or piezoelectric
elements for reception with reference to a sensor center position
serving as a reference for the delay time; a computer configured to
obtain a second receive signal by performing the steps of:
transmitting an ultrasonic wave from the element cluster set for
transmission, storing an ultrasonic wave received by the element
cluster set for reception as a first receive signal; repeating a
procedure for changing the element cluster set for transmission and
the element cluster set for reception and storing another first
receive signal; and summing up the plurality of first receive
signals obtained by repeating the same procedure; and a display
unit configured to display the second receive signal with reference
to the sensor center position.
[0050] The above-mentioned configuration makes it possible to
obtain high-resolution and high-S/N ratio testing results through
imaging by driving a number of piezoelectric elements, the
ultrasonic testing apparatus comprising less number of pulsers and
receivers in comparison with the number of elements composing the
array transducer.
[0051] In order to attain the above-mentioned first object, the
present invention provides an ultrasonic testing method for testing
the inside of an object under test and receiving reflected waves
(echoes) from the surface or inside thereof by using an ultrasonic
array transducer composed of a plurality of one- or
two-dimensionally arranged piezoelectric elements. The ultrasonic
testing method comprises the steps of: setting a plurality of
element groups (element clusters) to be used for transmission and
reception out of a plurality of piezoelectric elements composing
the ultrasonic array transducer; selecting an element cluster for
transmission out of the set plurality of element clusters, and
selecting an element cluster for reception out of the set plurality
of element clusters; giving a delay time to each of the
piezoelectric elements for transmission and/or the piezoelectric
elements for reception with reference to a sensor center position
serving as a reference for the delay time; transmitting an
ultrasonic wave from the element cluster set for transmission, and
storing an ultrasonic wave received by the element cluster set for
reception as a first receive signal; repeating a procedure for
changing the element cluster set for transmission and the element
cluster set for reception and storing another first receive signal;
summing up the plurality of first receive signals obtained by
repeating the same procedure to obtain a second receive signal; and
displaying the second receive signal with reference to the sensor
center position.
[0052] The above-mentioned method makes it possible to obtain
high-resolution and high-S/N ratio testing results through imaging
by driving a number of piezoelectric elements, the ultrasonic
testing apparatus comprising less number of pulsers and receivers
in comparison with the number of elements composing the array
transducer.
[0053] In order to attain the above-mentioned second object, the
present invention provides a method for three-dimensional
ultrasonic imaging comprising the steps of: transmitting an
ultrasonic wave from a two-dimensional array ultrasonic sensor to
focus at a desired depth; three-dimensionally scanning the inside
of an object under test while varying the ultrasonic beam angle,
and storing waveform data; converting the obtained waveform data to
three-dimensional testing data; storing the three-dimensional
testing data by sequentially changing the set position of the array
ultrasonic sensor; and combining the three-dimensional testing data
obtained at each testing position while making a shift by the
displacement of the array ultrasonic sensor to attain
three-dimensional imaging.
[0054] The above-mentioned method enables collective
three-dimensional imaging over a wide testing range based on high
resolution and high S/N ratio three-dimensional testing data and
allows images to be handled as one piece of three-dimensional
testing data by using a two-dimensional array ultrasonic sensor.
The present embodiment only utilizes one set of data processing
table (focal law) and is also applicable to thick objects and
high-attenuation materials.
[0055] In order to attain the above-mentioned second object, the
present invention provides an apparatus comprising: a
two-dimensional array ultrasonic sensor composed of a plurality of
piezoelectric elements; pulsers configured to transmit a transmit
signal to each piezoelectric element of the array ultrasonic
sensor; receivers configured to receive a receive signal; a delay
control unit configured to perform time control for the transmit
and receive signals by varying a delay time for each piezoelectric
element; a data storage unit configured to store ultrasonic
waveforms transmitted and received by the array ultrasonic sensor;
a sensor moving unit configured to move the array ultrasonic
sensor, and a scanning control unit configured to control the
sensor moving unit; a displacement detection unit configured to
measure the displacement of the array ultrasonic sensor; a computer
configured to convert the stored waveform data to three-dimensional
testing data, and combine the plurality of pieces of
three-dimensional testing data while making a shift by the
displacement of the array ultrasonic sensor measured by the
displacement detection unit; and a display unit configured to
display the combined testing data.
[0056] The above-mentioned configuration enables collective
three-dimensional imaging over a wide testing range based on high
resolution and high S/N ratio three-dimensional testing data and
allows images to be handled as one piece of three-dimensional
testing data by using a two-dimensional array ultrasonic sensor.
The present embodiment only utilizes one set of data processing
table (focal law) and is also applicable to thick objects and
high-attenuation materials.
[0057] Further, in order to attain the above-mentioned third
object, the present invention provides an apparatus comprising: an
ultrasonic sensor composed of a plurality of piezoelectric
elements; pulsers configured to supply a transmit signal to each
piezoelectric element of the ultrasonic sensor; receivers
configured to input a receive signal from each piezoelectric
element of the ultrasonic sensor; data storage unit configured to
store ultrasonic waveforms received by the ultrasonic sensor; a
computer for image processing configured to generate
three-dimensional testing data from the waveforms stored in the
data storage unit; and a three-dimensional display unit configured
to display the three-dimensional testing data generated by the
computer, wherein the computer outputs the distance between two
points specified on the three-dimensional display unit.
[0058] The above-mentioned configuration enables three-dimensional
measurement of the distance between echoes in a simple way in
sizing a defect such as a crack.
[0059] In order to attain the above-mentioned third object, the
present invention provides a three-dimensional ultrasonic testing
method for testing the inside of an object under test by
transmitting an ultrasonic wave to the object under test; and
receiving reflected waves therefrom by using an ultrasonic sensor
composed of a plurality of piezoelectric elements, wherein the
distance between two echoes caused by reflected ultrasonic wave
signals is measured based on the distance between two points
specified on the three-dimensional display unit.
[0060] The above-mentioned method enables three-dimensional
measurement of the distance between echoes in a simple way in
sizing a defect such as a crack.
BRIEF DESCRIPTION OF THE DRAWINGS
[0061] FIG. 1 is a block diagram illustrating a configuration of an
ultrasonic testing apparatus according to a first embodiment of the
present invention.
[0062] FIG. 2 illustrates a focal position setup in the ultrasonic
testing apparatus according to the first embodiment of the present
invention.
[0063] FIGS. 3 to 3 illustrates propagation times in the ultrasonic
testing apparatus according to the first embodiment of the present
invention.
[0064] FIG. 4 illustrates a relation between the propagation time
and the piezoelectric element number in the ultrasonic testing
apparatus according to the first embodiment of the present
invention.
[0065] FIG. 5 illustrates a relation between the delay time and the
piezoelectric element number in the ultrasonic testing apparatus
according to the first embodiment of the present invention.
[0066] FIG. 6 illustrates a receive signal obtained by a
combination of a plurality of element clusters in the ultrasonic
testing apparatus according to the first embodiment of the present
invention.
[0067] FIG. 7 illustrates receive signals obtained by a combination
of a plurality of element clusters in the ultrasonic testing
apparatus according to the first embodiment of the present
invention.
[0068] FIG. 8 illustrates image display in the ultrasonic testing
apparatus according to the first embodiment of the present
invention.
[0069] FIG. 9 illustrates image display in the ultrasonic testing
apparatus according to the first embodiment of the present
invention.
[0070] FIG. 10 illustrates image display in the ultrasonic testing
apparatus according to the first embodiment of the present
invention.
[0071] FIG. 11 is a flow chart illustrating detailed processing of
an ultrasonic testing method in the ultrasonic testing apparatus
according to the first embodiment of the present invention.
[0072] FIG. 12 illustrates an array transducer used in the
ultrasonic testing apparatus according to the first embodiment of
the present invention.
[0073] FIG. 13 illustrates an array transducer used in the
ultrasonic testing apparatus according to the first embodiment of
the present invention.
[0074] FIG. 14 illustrates an effective range of a focal beam
obtained in the ultrasonic testing apparatus according to the first
embodiment of the present invention.
[0075] FIG. 15 illustrates a sensor center position setup in an
ultrasonic testing apparatus according to a second embodiment of
the present invention.
[0076] FIG. 16 illustrates a sensor center position setup in the
ultrasonic testing apparatus according to the second embodiment of
the present invention.
[0077] FIG. 17 illustrates a sensor center position setup in the
ultrasonic testing apparatus according to the second embodiment of
the present invention.
[0078] FIG. 18 illustrates element cluster combination setups in an
ultrasonic testing apparatus according to a third embodiment of the
present invention.
[0079] FIG. 19 illustrates a display screen in the ultrasonic
testing apparatus according to the third embodiment of the present
invention.
[0080] FIG. 20 illustrates element cluster combination setups in
the ultrasonic testing apparatus according to the third embodiment
of the present invention.
[0081] FIG. 21 illustrates the display screen in the ultrasonic
testing apparatus according to the third embodiment of the present
invention.
[0082] FIG. 22 is a block diagram illustrating a configuration of a
three-dimensional ultrasonic imaging apparatus according to a
fourth embodiment of the present invention.
[0083] FIG. 23 illustrates an operation of a two-dimensional array
ultrasonic sensor used in the three-dimensional ultrasonic imaging
apparatus according to the fourth embodiment of the present
invention.
[0084] FIG. 24 illustrates an operation of three-dimensional
ultrasonic scanning (volume scan) by the two-dimensional array in
the three-dimensional ultrasonic imaging apparatus according to the
fourth embodiment of the present invention.
[0085] FIG. 25 illustrates an operation of three-dimensional
ultrasonic scanning n (volume scan) by the two-dimensional array in
the three-dimensional ultrasonic imaging apparatus according to the
fourth embodiment of the present invention.
[0086] FIG. 26 illustrates an operation of three-dimensional
ultrasonic scanning (volume scan) by the two-dimensional array in
the three-dimensional ultrasonic imaging apparatus according to the
fourth embodiment of the present invention.
[0087] FIG. 27 illustrates processing of three-dimensional testing
data in the three-dimensional ultrasonic imaging apparatus
according to the fourth embodiment of the present invention of
operation.
[0088] FIG. 28 illustrates processing of three-dimensional testing
data in the three-dimensional ultrasonic imaging apparatus
according to the fourth embodiment of the present invention of
operation.
[0089] FIG. 29 is a flow chart illustrating detailed processing of
three-dimensional ultrasonic imaging in the three-dimensional
ultrasonic imaging apparatus according to the fourth embodiment of
the present invention.
[0090] FIG. 30 is a flow chart illustrating detailed processing of
three-dimensional ultrasonic imaging in the three-dimensional
ultrasonic imaging apparatus according to the fourth embodiment of
the present invention.
[0091] FIG. 31 illustrates processing of three-dimensional testing
data in a three-dimensional ultrasonic imaging apparatus according
to a fifth embodiment of the present invention of operation.
[0092] FIG. 32 is a flow chart illustrating detailed processing of
three-dimensional ultrasonic imaging in the three-dimensional
ultrasonic imaging apparatus according to the fifth embodiment of
the present invention.
[0093] FIG. 33 illustrates processing of three-dimensional testing
data in a three-dimensional ultrasonic imaging apparatus according
to a sixth embodiment of the present invention of operation.
[0094] FIG. 34 is a flow chart illustrating detailed processing of
three-dimensional ultrasonic imaging in the three-dimensional
ultrasonic imaging apparatus according to the sixth embodiment of
the present invention.
[0095] FIG. 35 is a block diagram illustrating a configuration of a
three-dimensional ultrasonic testing apparatus according to a
seventh embodiment of the present invention.
[0096] FIG. 36 illustrates an exemplary three-dimensional display
screen in the three-dimensional ultrasonic testing apparatus
according to the seventh embodiment of the present invention.
[0097] FIGS. 37A to 37D illustrate an exemplary three-dimensional
scanning method in the three-dimensional ultrasonic testing
apparatus according to the seventh embodiment of the present
invention.
[0098] FIG. 38 illustrates an exemplary two-dimensional display
screen of a testing result obtained by the three-dimensional
scanning method in the three-dimensional ultrasonic testing
apparatus according to the seventh embodiment of the present
invention.
[0099] FIG. 39 illustrates an exemplary three-dimensional display
screen of a testing result obtained by the three-dimensional
scanning method in the three-dimensional ultrasonic testing
apparatus according to the seventh embodiment of the present
invention.
[0100] FIG. 40 illustrates another three-dimensional scanning
method in the three-dimensional ultrasonic testing apparatus
according to the seventh embodiment of the present invention.
[0101] FIG. 41 is a flow chart illustrating detailed processing of
a crack sizing method in the three-dimensional ultrasonic testing
apparatus according to the seventh embodiment of the present
invention.
[0102] FIG. 42 is a flow chart illustrating detailed processing of
the crack sizing method in the three-dimensional ultrasonic testing
apparatus according to the seventh embodiment of the present
invention.
[0103] FIG. 43 illustrates a method for selecting a point on the
three-dimensional display screen in the three-dimensional
ultrasonic testing apparatus according to the seventh embodiment of
the present invention.
[0104] FIGS. 44A, 44B illustrate a method for selecting a point
having a maximum echo value on the three-dimensional display screen
in the three-dimensional ultrasonic testing apparatus according to
the seventh embodiment of the present invention.
[0105] FIG. 45 illustrates exemplary linear display of a
three-dimensional scale on the three-dimensional display screen in
the three-dimensional ultrasonic testing apparatus according to the
seventh embodiment of the present invention.
[0106] FIGS. 46A, 46B illustrate exemplary display of information
about positions with reference to other than a crack in the
three-dimensional ultrasonic testing apparatus according to the
seventh embodiment of the present invention.
[0107] FIG. 47 is a block diagram illustrating another
configuration of the three-dimensional ultrasonic testing apparatus
used for the seventh embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0108] Configuration and operation of an ultrasonic testing
apparatus according to a first embodiment of the present invention
will be described below with reference to FIGS. 1 to 14.
[0109] First of all, the configuration of the ultrasonic testing
apparatus according to the present embodiment will be described
below with reference to FIG. 1.
[0110] FIG. 1 is a block diagram illustrating a configuration of
the ultrasonic testing apparatus according to the first embodiment
of the present invention.
[0111] The ultrasonic testing apparatus according to the present
embodiment includes an ultrasonic array transducer 101 which
transmits ultrasonic waves to an object under test 100, a
transmitter/receiver 102, and a display unit 103 which displays
testing images. The present embodiment tests a reflection source
111 such as a defect and a crack in the inside or on the surface of
the object under test 100 by imaging.
[0112] The ultrasonic array transducer 101 is basically composed of
a plurality of one- or two-dimensionally arranged piezoelectric
elements 104, each being able to transmit and receive an ultrasonic
wave. The ultrasonic array transducer 101 is disposed on a testing
surface of the object under test 100 through a coupling medium
(such as water, glycerin, or other liquids) or a shoe (made of a
synthetic resin such as acrylics). The ultrasonic array transducer
101 transmits an ultrasonic wave 105 by using a drive signal
supplied from the transmitter/receiver 102, propagates the
ultrasonic wave 105 in the object under test 100, detects a
reflected wave (echo) 106, and sends a receive signal to the
transmitter/receiver 102.
[0113] The array transducer 101 of FIG. 1 is composed of N
piezoelectric elements (N=Na+Nb+Nc+Nd) and connected to the
transmitter/receiver 102 through connectors and cables. Suppose
that numbers Na, Nb, Nc, and Nd are all the same, for example, 64,
and therefore N is 256. However, the numbers Na, Nb, Nc, and Nd may
not necessarily be the same.
[0114] With the present embodiment, N piezoelectric elements are
grouped into four different groups of piezoelectric elements, i.e.,
an element cluster 101A composed of piezoelectric element #1 to
#Na, an element cluster 101B composed of element #1 to #Nb, an
element cluster 101C composed of element #1 to #Nc, and an element
cluster 101D composed of element #1 to #Nd. The ultrasonic array
transducer 101 transmits and receives ultrasonic waves on an
element cluster basis.
[0115] The transmitter/receiver 102 transmits and receives
ultrasonic waves by using the ultrasonic array transducer 101. The
transmitter/receiver 102 includes a transmission selector circuit
102A, a reception selector circuit 102B, a pulser 102C, a receiver
102D, a delay time controller 102E, a sensor information setter
102F, a computer 102G, data storage 102H, and an image processor
102M. The sensor information setter 102F determines an element
group (the element cluster 101A) to be used for transmission, and
based on the determination, the transmission selector circuit 102A
electrically connects the element cluster 101A and the pulser 102C.
Then, the pulser 102C supplies a drive signal to the ultrasonic
array transducer 101, and the element cluster 101A for transmission
in the ultrasonic array transducer transmits the ultrasonic wave
105. When the ultrasonic wave 105 transmitted to the inside of the
object under test 100 is reflected, for example, by the reflection
source 111, a reflected ultrasonic wave 106 (echo) is generated.
Then, in a similar way to transmission, the sensor information
setter 102F determines an element cluster (the element cluster
101D) to be used for reception, and the reception selector circuit
102B electrically connects the element cluster 101D and the
receiver 102D. The receiver 102D processes a receive signal.
[0116] Therefore, when the ultrasonic array transducer 101 is
composed of 256 piezoelectric elements and each of the four element
clusters is composed of 64 piezoelectric elements, for example, the
transmitter/receiver 102 requires pulser, receiver, and wiring
circuits accommodating 64 piezoelectric elements. With the present
embodiment, however, the near-sound-field limit distance (NF) can
be deeper than that in a case where each element cluster is
composed of 64 piezoelectric elements, that is, the NF can be
equivalent to that in a case where each element cluster is composed
of 256 piezoelectric elements, as described in detail below.
[0117] The computer 102G controls the transmission selector circuit
102A, the reception selector circuit 102B, the pulser 102C, the
receiver 102D, the delay time controller 102E, the data storage
102H, and the image processor M to perform required operations, as
well as combines signals stored in the data storage 102H to perform
imaging.
[0118] The sensor information setter 102F groups N piezoelectric
elements composing the ultrasonic array transducer 101 into a
plurality of piezoelectric element groups (element clusters). Then,
the sensor information setter 102F sets a sensor center position
103A to be used as a reference for delay time and display, and
calculates a delay time to be given to the array transducer 101 by
using the computer 102G or stores precalculated data. Based on this
delay time, the delay time controller 102E gives a delay pattern to
the array transducer 101. When the sensor information setter 102F
sets element clusters, it may be possible that the computer 102G
sets the center position of the set piezoelectric element groups as
the sensor center position 103A.
[0119] The transmission selector circuit 102A and the reception
selector circuit 102B) respectively selects an element cluster used
for transmission and an element cluster used for reception. For
example, when the ultrasonic array transducer 101 is composed of N
piezoelectric elements and four element clusters 101A to 101D, the
ultrasonic array transducer 101 repeats the following operations:
(1) transmission by the element cluster 101A and reception by the
element cluster 101A, (2) transmission by the element cluster 101A
and reception by the element cluster 101B, . . . based on a pattern
determined by the sensor information setter 102F. For example, when
the array transducer 101 is grouped into four element clusters 101A
to 101D, as shown in FIG. 1, four different element clusters are
available for both transmission and reception. Therefore, a
combination of element clusters for transmission and reception is
selected from a total of 16 (4.times.4) different combinations.
[0120] Signals received by piezoelectric elements of an element
cluster for reception are subjected to A/D conversion, given a
delay time based on a delay time pattern, and combined into (summed
up to) one receive signal (first receive signal). Therefore, for
example, when there are four different element clusters for
transmission and four different element clusters for reception,
i.e., 16 (4.times.4) different combinations of element clusters are
available, a total of 16 first receive signals is stored in the
data storage 102H.
[0121] The computer 102A combines (sums up) the first receive
signals stored in the data storage 102H to derive a second receive
signal. This second receive signal is displayed on the display unit
103 as an ultrasonic image. In this case, the sensor center
position 103A which is a reference for delay time is also used as a
reference position for image display.
[0122] Operations of the ultrasonic testing apparatus according to
the present embodiment will be described below with reference to
FIGS. 2 to 9.
[0123] Hereinafter, a first receive signal obtained by transmission
by the i-th element cluster and reception by the j-th element
cluster is referred to as .PHI.ij.
[0124] First of all, a focal position set by the ultrasonic testing
apparatus according to the present embodiment will be described
below with reference to FIG. 2.
[0125] FIG. 2 illustrates the focal position set by the ultrasonic
testing apparatus according to the first embodiment of the present
invention.
[0126] The following description will be made on the premise that,
in order to test the object under test 100, the sensor information
setter 102F sets a focal position F as a position at which
ultrasonic beams are focused (namely, focal point).
[0127] Of N piezoelectric elements composing the ultrasonic array
transducer 101, Na piezoelectric elements constitute the element
cluster 101A. Further, the sensor information setter 102F sets a
point C as a sensor center position. For example, a delay time for
the i-th element of the element cluster A is obtained with the
following procedures:
[0128] A round-trip propagation time T between the sensor center
position C and the focal position F is obtained by dividing two
times a line CF by the ultrasonic velocity in the object under
test. Similarly, a round-trip propagation time T between a
piezoelectric element I and the focal point F is obtained by
dividing two times a line IF by the sonic velocity therein.
[0129] In order to allow the ultrasonic wave to focus at the focal
point F, it is necessary that ultrasonic beams from the
piezoelectric elements reach the focal point F at the same time and
be in phase thereat. Further, since the reference position for a
final ultrasonic image is set to the point C, the distance of
ultrasonic propagation needs to coincide with the line CF when the
focal point F is measured by the ultrasonic array transducer 101.
As mentioned above, it is preferable to apply delay processing to
each element so that the propagation time from each element to the
focal point coincide with the propagation time from the sensor
center position to the focal point.
[0130] Propagation time and delay time in the ultrasonic testing
apparatus according to the present embodiment will be described
below with reference to FIGS. 3 to 5.
[0131] FIG. 3 illustrates propagation times in the ultrasonic
testing apparatus according to the first embodiment of the present
invention. FIG. 4 illustrates a relation between the propagation
time and the piezoelectric element number in the ultrasonic testing
apparatus according to the first embodiment of the present
invention. FIG. 5 illustrates a relation between the delay time and
the piezoelectric element number in the ultrasonic testing
apparatus according to the first embodiment of the present
invention.
[0132] FIG. 3 (A) illustrates a round-trip propagation time T
between the sensor center position C and the focal position F,
i.e., the propagation time for paths CF and FC. FIG. 3 (B)
illustrates a round-trip propagation time T between the
piezoelectric element I and the focal position F, i.e., the
propagation time for paths IF and FI. FIG. 3 (C) illustrates a
delay time for paths IF and FI.
[0133] A difference .DELTA. T(1) between the above-mentioned two
propagation times is represented by formula (2).
[Formula 2]
.DELTA.T(I)=T(IF)+T(FI)-(T(CF)+T(FC)) (2)
where T(IF)+T(FI) is the propagation time for the paths IF and FI,
and T(CF)+T(FC) is the propagation time for the paths CF and
FC.
[0134] When delay processing by the difference .DELTA. T(I) between
T(CF)+T(FC) and T(IF)+T(FI) is applied to the propagation time, the
propagation time for the element I, (.DELTA. T(I)+T(IF)+T(FI)),
coincides with the propagation time for the sensor center position,
(T(CF)+T(FC)).
[0135] A delay time pattern for the ultrasonic array transducer 101
can be obtained by applying such delay processing to all the
piezoelectric elements.
[0136] FIG. 4 illustrates a relation between the piezoelectric
element number and the propagation time T to the focal point. With
reference to a propagation time T0 from the sensor center position
103A to the focal point, the propagation time T0 is subtracted from
the propagation time T for each piezoelectric element.
[0137] Then, as shown in FIG. 5, a delay time .DELTA.T for each
piezoelectric element can be obtained.
[0138] Thus, after giving a delay time .DELTA.T (I) to each
piezoelectric element, a first receive signal for each element is
stored one by one.
[0139] A receive signal obtained by the combination of a plurality
of element clusters in the ultrasonic testing apparatus according
to the present embodiment will be described below with reference to
FIGS. 6 and 7.
[0140] FIGS. 6 and 7 illustrates a receive signal obtained by the
combination of a plurality of element clusters in the ultrasonic
testing apparatus according to the first embodiment of the present
invention.
[0141] FIG. 6 is a schematic view of the ultrasonic array
transducer 101 composed of four element clusters A to D. A delay
time calculated by formula (2) is set for each piezoelectric
element of the element clusters A to D. When the element cluster A
transmits an ultrasonic wave and the element cluster D receives a
reflected wave, it is stored in the data storage 102H as a first
receive signal .PHI.AD.
[0142] When there are four element clusters, first receive signals
.PHI.ij are sequentially stored while selecting one of 16
combinations of transmission and reception, as shown in FIG. 7.
[ Formula 3 ] .PSI. ( F ) = i = 1 M j = 1 M .PHI. ij ( 3 )
##EQU00001##
[0143] Finally, as shown by formula (3), all the first receive
signals .PHI.ij are combined (summed up) to derive a second receive
signal .PSI.(F) for the focal point F.
[0144] Image display in the ultrasonic testing apparatus according
to the present embodiment will be described below with reference to
FIGS. 8 to 10.
[0145] FIGS. 8 to 10 illustrate image display in the ultrasonic
testing apparatus according to the first embodiment of the present
invention.
[0146] In actual testing, since a plurality of focal positions are
two- or three-dimensionally scanned, a plurality of second receive
signals .PSI.(F) are combined for each focal position, as shown in
FIG. 8. The second receive signal .PSI.(F) can be represented as a
graph 801 when the vertical axis is assigned amplitude and the
horizontal axis is assigned time. Hereinafter, a value of a second
receive signal .PSI.(Fi) set at an i-th focal point Fi at a time t
is represented by .PSI.(Fi;t).
[0147] The display unit 103 displays the second receive signal
.PSI.(Fi;t) as a two- or three-dimensional image.
[0148] In order to constitute a two- or three-dimensional image
from the second receive signal .PSI.(F), a pixel value for a pixel
901 is obtained and then pixel values between second receive
signals .PSI. are interpolated, as shown in FIG. 9.
[0149] An exemplary method for calculating a pixel value will be
described below with reference to FIG. 10 and formula (4).
[0150] The first receive signals .PHI.ij are combined (summed up)
to derive a second receive signal for the focal point F, .PSI.(F).
Since each pixel is sandwiched by two receive signals (.PSI.(Fi;t)
and .PSI.(Fi+1;t)) corresponding to a certain focus point (Fi and
Fi+1, respectively) as shown in FIG. 9, a pixel value can be
obtained by using the second receive signals .PSI.. Specifically,
as shown in FIG. 10, a distance L between a reference position C
and a certain pixel P [m,n] is divided by the sonic velocity V in
an object under test to obtain a propagation time .tau.=L/V. Then,
signals .PSI.(Fi;.tau.) and .PSI.(Fi+1;.tau.) corresponding to time
.tau., as well as a point Fi(.tau.) corresponding to the distance L
from the reference position C through a respective focal point Fi
are obtained. A weight W(i) is obtained from the ratio of the
length of a line FiFi+1 defined by the point Fi(.tau.) and a point
Fi+1(.tau.) to the length of a line PFi+1 defined by a pixel point
P[m,n] and the point Fi+1(.tau.) (Formula (4)).
[ Formula 4 ] .PSI. ( P [ m , n ] ; .tau. ) = W ( i ) .times. .PSI.
( Fi ; .tau. ) + W ( i + 1 ) .times. .PSI. ( Fi + 1 ; .tau. ) where
W ( i ) = PFi + 1 ( .tau. ) _ Fi ( .tau. ) Fi + 1 ( .tau. ) _ ( 4 )
##EQU00002##
[0151] The weight W(i) is multiplied by .PSI. and then subjected to
weighted averaging to obtain .PSI.(P[m,n];.tau.). The testing
process repeats this processing for each pixel to obtain two- or
three-dimensional pixel values. Then, testing results are
displayed, for example, as monochrome or color images according to
the size of the pixel values. Resultant images are displayed, for
example, as a sectional view 103B in the direction of plate
thickness of FIG. 1 and a graph 103C illustrating a relation
between time and amplitude.
[0152] The ultrasonic testing method in the ultrasonic testing
apparatus according to the present embodiment will be described
below with reference to FIGS. 11 to 13.
[0153] FIG. 11 is a flow chart illustrating detailed processing of
the ultrasonic testing method in the ultrasonic testing apparatus
according to the first embodiment of the present invention. FIGS.
12 and 13 illustrate array transducers used for the ultrasonic
testing apparatus according to the first embodiment of the present
invention.
[0154] Detailed processing of the ultrasonic testing method
according to the present embodiment in FIG. 11 is roughly divided
into three blocks.
[0155] The ultrasonic array transducer 101 composed of N
piezoelectric elements is disposed on the object under test 100. A
first block (steps S1101 to S1104) relates to initial setup for the
ultrasonic array transducer 101. In Step S1101 (initial setup), the
testing process sets the ultrasonic velocity of the object under
test, the number of piezoelectric elements (N), and arrangements
and interval of piezoelectric elements 104 composing the array
transducer 101.
[0156] In the case of an array transducer 1201 composed of
one-dimensionally arranged piezoelectric elements, the position of
piezoelectric elements distributed in the array transducer 1201 can
be grasped by setting an interval 1202 and arrangements of N
piezoelectric elements, as shown in FIG. 12.
[0157] In the case of an array transducer 1301 composed of
two-dimensionally arranged piezoelectric elements, the position of
piezoelectric elements distributed in the array transducer 1301 can
be grasped by setting intervals 1302 and 1303 and arrangements of N
piezoelectric elements (N=P columns.times.Q rows), as shown in FIG.
13.
[0158] The testing process sets a delay time and a sensor center
position to be used as a reference for image display to these N
piezoelectric elements (step S1102 of FIG. 11). Generally, as shown
in FIGS. 12 and 13, the testing process sets a center (an
intersection of center lines 1203A and 1203B of FIG. 12 or an
intersection of center lines 1303A and 1303B of FIG. 13) of
piezoelectric elements as a sensor center position C.
[0159] Then, as described with reference to FIGS. 2 to 5, the
testing process calculates a delay time pattern for each element of
the array transducer with respect to a single or a plurality of
focal points F (step S1103).
[0160] The testing process sets an element or element group
(element cluster) to be used for transmission and reception when
storing a first receive signal (step S1104). For example, as shown
in FIG. 6, suppose a case where N piezoelectric elements are
grouped into four different element groups (A to D). For example,
with the one-dimensionally arranged array transducer 1201 of FIG.
12 composed of N(=256) elements, element #1 to #64 are grouped as
the cluster A, element #65 to #128 are grouped as the cluster B,
element #129 to #196 are grouped as the cluster C, and element #197
to #256 are grouped as the cluster D. With a two-dimensionally
arranged array transducer 1301 of FIG. 13 composed of N(=256)
elements (N=P columns.times.Q rows, P=Q=16), column #1 to #8
(P=1-8) and row #1 to #8 (Q=1-8) are grouped as the cluster A,
column #1 to #8 (P=1-8) and row #9 to #16 (Q=9-16) are grouped as
the cluster B, column #9 to #16 (P=9-16) and row #1 to #8 (Q=1-8)
are grouped as the cluster C, and column #9 to #16 (P=9-16) and row
#9 to #16 (Q=9-16) are grouped as the cluster D.
[0161] A second block (steps S1105 to S1109) relates to processing
of first receive signals.
[0162] The testing process stores the first receive signal for the
focal point F used for delay time setup. First of all, the testing
process sets a delay time at a certain focal point F(i) (step
S1105). Then, the testing process sets an element cluster for
transmission and an element cluster for reception. For example,
when there are four different element clusters A to D, the testing
process sets the cluster A for transmission and the cluster A for
reception (step S1106). Then, the testing process stores a receive
signal by using the element cluster for transmission and the
element cluster for reception (step S1107), and changes the element
clusters for transmission and reception (step S1108). The testing
process repeats steps S1106 to S1108 for each element cluster, and
stores the first receive signal for a certain focal position F
(step S1109). For example, when there are four element clusters,
the testing process stores 16(4.times.4) first receive signals
.PHI.ij, as shown in FIG. 7. When there is a plurality of focal
points, the testing process repeats steps S1105 to S1109 for each
focal point to store first receive signals corresponding to the
number of focal points.
[0163] A third block (steps S1110 to S1114) relates to processing
of second receive signals and display.
[0164] First of all, the testing process combines (sums up) first
receive signals .PHI. based on formula (3) to derive a second
receive signal .PSI. (step S1110). Then, the testing process sets a
range (a pixel) for image display (step S1111). Then, as mentioned
above with reference to FIGS. 8 to 10 and formula (4), the testing
process calculates a pixel value for a pixel P through
interpolation based on second receive signals .PSI. corresponding
to the number of focal points (step S1112). The testing process
maps a pixel value corresponding to the pixel P (step S1113), and
displays it on the image display unit 103 (step S1114).
[0165] Then, an effective range of a focal beam obtained by the
ultrasonic testing apparatus according to the present embodiment
will be described below with reference to FIG. 14.
[0166] FIG. 14 illustrates the effective range of the focal beam
obtained by the ultrasonic testing apparatus according to the first
embodiment of the present invention.
[0167] FIG. 14 illustrates the effective range (near-sound-field
limit distance NF) of the focal beam obtained by the present
embodiment. The testing process performs calculation with a
frequency of 2 MHz and a sonic velocity of steel material of 6000
m/s.
[0168] When there is one element cluster, the effective focused
beam is obtained at a depth less than 50 mm even if the element
cluster is 16 mm wide.
[0169] According to the present embodiment having four element
clusters, when the aperture of one element cluster is 16 mm wide
(sensor width), the substantial sensor aperture becomes 64 mm wide
by combining a plurality of receive signals. Therefore, an
ultrasonic beam is sufficiently effective at a depth of 300 mm or
more.
[0170] As mentioned above, the present embodiment combines the
pulser and receiver circuit configuration suitable for element
clusters for first receive signals with signal combination
processing for second receive signals. This enables imaging by
driving a number of piezoelectric elements while maintaining the
apparatus compact as well as use the focal beam with a large
substantial sensor aperture, thus obtaining testing images with
high resolution and high S/N ratio.
[0171] Configuration and operation of an ultrasonic testing
apparatus according to a second embodiment of the present invention
will be described below with reference to FIGS. 15 to 17. The
configuration of the ultrasonic testing apparatus according to the
present embodiment is the same as that shown in FIG. 1.
[0172] First of all, a sensor center position setup in the
ultrasonic testing apparatus according to the present embodiment
will be described below with reference to FIGS. 15 and 16.
[0173] FIGS. 15 and 16 illustrate a sensor center position setup in
the ultrasonic testing apparatus according to the second embodiment
of the present invention.
[0174] With the present embodiment, although processing flow is the
same as that of the first embodiment, the sensor center position
setup (step S1102 of the flow chart in FIG. 11) is extended.
[0175] Although all the piezoelectric elements composing an
ultrasonic array transducer are grouped into a plurality of element
clusters in the first embodiment, FIG. 15 shows a case where a part
of piezoelectric elements composing the array transducer are
partially used for element cluster setup. With an array transducer
composed of two-dimensionally arranged N(=P.times.Q) piezoelectric
elements, for example, only column #1 to #P' and row #1 to #Q' are
used for testing, and an intersection of two center lines 1502A and
1502B for a region of P'.times.Q' piezoelectric elements is set as
a sensor center position C'. In this case, it can be considered
that the region of P'.times.Q' piezoelectric elements serves as a
virtual array transducer. This also applies to a one-dimensional
array although an exemplary two-dimensionally array is shown in
FIG. 15.
[0176] Further, as shown in FIG. 16, a virtual array transducer may
be set to the outside of a real ultrasonic array transducer. In
this case, a portion shown as a region 1601 serves as a virtual
array transducer, and an intersection of two center lines 1602A and
1602B is set as a sensor center position C'.
[0177] If flexibility is given to a setup of sensor center position
(a reference for delay time and image display) in this way, desired
piezoelectric elements can be used to constitute a virtual array
transducer depending on the thickness of an object under test.
Specifically, when imaging a shallow (thin) region of the object
under test, the number of piezoelectric elements is decreased. When
imaging a deep (thick) region of the object under test, the number
of piezoelectric elements is increased. This makes it possible, for
example, to maintain a constant resolution of images in the depth
direction.
[0178] Another exemplary sensor center position setup in the
ultrasonic testing apparatus according to the present embodiment
will be described below with reference to FIG. 17.
[0179] FIG. 17 illustrates a sensor center position setup in the
ultrasonic testing apparatus according to the second embodiment of
the present invention.
[0180] An image over a wider range can be obtained by setting a
virtual array transducer to the outside of a real array transducer.
An image over a wide range will be schematically described below
with reference to FIG. 17.
[0181] When the array transducer 101 performs imaging at the sensor
center position 103A thereof according to the first embodiment,
images can be obtained within a range of a fan 1701A but pixel
values cannot be obtained in regions 1702A and 1702B. When the
virtual array transducer is set in the region 1601, the sensor
center position can be set to a point 1703, allowing images to be
obtained within a range of a fan 1701B. Thus, imaging can be
performed over a wider range. For example, suppose a case where an
array transducer is disposed on the outer circumference of a bent
pipe. If the sensor cannot be brought any closer to the bent
portion on the pipe, setting a virtual array transducer as shown in
FIG. 17 makes it possible to test portions closer to the bent
portion. This effect of obtaining images over a wider range is also
applicable to a case where the elements of the array transducer are
partially used as a virtual array transducer, as shown in FIG.
15.
[0182] As mentioned above, according to the present embodiment,
setting a virtual array transducer as well as a relevant sensor
center position makes it possible to adjust resolution in the depth
direction, allowing imaging over a wider range.
[0183] Configuration and operation of an ultrasonic testing
apparatus according to a third embodiment of the present invention
will be described below with reference to FIGS. 18 to 21. The
configuration of the ultrasonic testing apparatus according to the
present embodiment is the same as that shown in FIG. 1.
[0184] FIGS. 18 and 20 illustrate element cluster combination
setups in the ultrasonic testing apparatus according to the third
embodiment of the present invention. FIGS. 19 and 21 illustrate
display screens in the ultrasonic testing apparatus according to
the third embodiment of the present invention.
[0185] With the present embodiment, the array transducer 101 is
composed of four element clusters.
[0186] FIGS. 18 and 20 illustrate exemplary element cluster
combination setups used for transmission and reception. FIG. 18
illustrates a case where a second receive signal .PSI. is derived
from all the 16 first receive signals .PHI. obtained by the four
element clusters. These combinations of element clusters are the
same as those shown in FIG. 7.
[0187] FIG. 20 illustrates a case where a second receive signal W
is derived from 12 first receive signals .PHI. obtained by
combinations of different element clusters for transmission and
reception. Combinations marked .smallcircle. are used but
combinations marked x are not.
[0188] When the same element cluster is used both for transmission
and reception, a transmission signal drifting into the same element
(or the same element cluster) causes signals (1901A and 1901B of
FIG. 19) which serve as noise forming a dead zone in the vicinity
of the array transducer. When different elements or element
clusters are used for transmission and reception, signals (2101A
and 2101B of FIG. 21) accompanying transmission can be reduced,
resulting in a reduced dead zone.
[0189] On the other hand, when the element cluster combinations of
FIG. 18 are used, the sensitivity can be increased allowing deeper
portions to be tested.
[0190] Therefore, for example, deep portions are initially tested
by using the element cluster combinations of FIG. 18, and if a
detected defect (a crack or the like) extends to a shallower
portion, the element cluster combinations are changed to those of
FIG. 20 to enable shallower portions to be subsequently tested.
[0191] According to the present embodiment, selecting a combination
of different element clusters for transmission and/or reception,
each element cluster being composed of a single or a plurality of
elements, makes it possible to separate element(s) (element
clusters) for transmission from element(s) (element clusters) for
reception, thus reducing noise signals (such as a transmitting
pulse, an echo in a shoe, etc.) accompanying ultrasonic
transmission.
[0192] Configuration and operation of a three-dimensional
ultrasonic imaging apparatus according to a fourth embodiment of
the present invention will be described below with reference to
FIGS. 22 to 30.
[0193] First of all, the configuration of the three-dimensional
ultrasonic imaging apparatus according to the present embodiment
will be described below with reference to FIG. 22.
[0194] FIG. 22 is a block diagram illustrating the configuration of
the three-dimensional ultrasonic imaging apparatus according to the
fourth embodiment of the present invention.
[0195] The three-dimensional ultrasonic imaging apparatus according
to the present embodiment includes: a two-dimensional array
ultrasonic sensor 101X configured to transmit an ultrasonic wave to
an object under test 100; a transmitter/receiver 102X; a display
unit 103X configured to display a receive signal and
three-dimensional testing data; a scanning unit controller 105X
configured to feed the two-dimensional array ultrasonic sensor
101X; a displacement detector 106X configured to detect a
displacement of the ultrasonic sensor 101X; and a sensor scanning
unit 107 configured to feed the two-dimensional array ultrasonic
sensor 101X.
[0196] The array ultrasonic sensor 101X is composed of
piezoelectric elements 104X each transmitting an ultrasonic wave as
shown in FIG. 22. The array ultrasonic sensor 101X is set on a
testing surface of an object under test 100, transmits an
ultrasonic wave 108X by a drive signal supplied from the
transmitter/receiver 102X, propagates the ultrasonic wave 108X in
the object under test 100, measures a reflected echo therefrom, and
supplies a receive signal to the transmitter/receiver 102.
[0197] The transmitter/receiver 102X includes a computer 102XA, a
delay time controller 102XB, a pulser 102XC, a receiver 102XD, and
data storage 102XE. The pulser 102XC supplies a drive signal to an
array transducer 101X, and the receiver 102XD processes the receive
signal received from the array ultrasonic sensor 101X. The computer
102XA controls the delay time controller 102XB, the pulser 102XC,
the receiver 102XD, and the data storage 102XE to perform necessary
operations.
[0198] The delay time controller 102XB controls the timing of drive
signal output from the pulser 102XC as well as the timing of
receive signal input to the receiver 102XD to attain operations of
the two-dimensional array ultrasonic sensor 101 employing the
phased array method. The two-dimensional array ultrasonic sensor
101X employing the phased array method controls a focal depth of
the ultrasonic wave 108X and at the same time three-dimensionally
controls its beam angle 109X in the object under test 100 during
transmission and reception of the ultrasonic wave 108X.
[0199] The data storage 102XE processes the receive signal supplied
from the receiver 102XD and then supplies it to the computer 102XA.
The computer 102XA processes the stored testing data and then
displays the data on the display unit 103.
[0200] Processing in the computer 102XA and operation of the
display unit 103X will be described in detail later. The computer
102XA combines waveforms obtained by the piezoelectric elements in
relation to a delay time, converts a waveform for each beam angle
of each ultrasonic wave to three-dimensional testing data, and
displays three-dimensional testing data 103XB on the display unit
103X.
[0201] Further, the computer 102XA combines (sums up or averages) a
plurality of pieces of three-dimensional testing data 103XB
obtained at each position according to operations of the scanning
unit controller 105X and the displacement detector 106X to be
mentioned later, and displays the combined three-dimensional
testing data as a three-dimensional processing image 103XC on the
display unit 103X. The display unit 103X displays three-dimensional
testing data as mentioned above, and is provided with a function to
display a receive waveform 103XA corresponding to a position at a
desired ultrasonic beam angle 103XF in testing data.
[0202] FIG. 22 illustrates a case where a defect 110X exists on the
bottom surface of the object under test 100. In this case, a defect
corner echo 103XK, a defect tip echo 103XJ, and a bottom echo 103XI
of the object under test are observed at a bottom position 103XE in
the three-dimensional testing data 103XB and the three-dimensional
processing image 103XC. When sizing the depth of the defect on the
bottom surface, the distance between the bottom position 103XE and
a defect tip echo position 103XD obtained in the three-dimensional
processing data 103XC is used. Also in a combined waveform 103XA at
a desired ultrasonic beam angle, reflected echoes 103XJ and 103XK
corresponding to these echoes are observed.
[0203] A position controller of the scanning unit controller 105X
receives a movement signal, including moving speed and
displacement, from the computer 102XA, and drives a sensor moving
unit 107X based on this signal to move the set position of the
two-dimensional array ultrasonic sensor 101X. The sensor moving
unit 107X is connected to the displacement detector 106X to measure
an actual displacement of the array ultrasonic sensor 101X. FIG. 22
illustrates a case where the array ultrasonic sensor 101X moves a
testing start position 101XA (a set position of the array
ultrasonic sensor 101X at the start of testing) to a testing end
position 101XC (a set position of the array ultrasonic sensor 101X
at the end of testing).
[0204] A measured displacement is sent to the computer 102XA and
then used to process testing data. A displacement at each testing
position of the ultrasonic sensor 101X is measured by the
displacement detector 106X, and the displacement is used in the
computer 102XA to make a shift in the three-dimensional testing
data during data combination (summation (or averaging)) (details
will be described later).
[0205] Since the ultrasonic imaging apparatus according to the
present embodiment can also perform conventional testing operations
based on a two-dimensional array ultrasonic sensor, it is necessary
to switch between this operation mode and an operation mode for the
above-mentioned three-dimensional testing data combination
(summation (or averaging)) processing. The conventional operation
mode does not perform the combination processing. In the
conventional operation mode, as the two-dimensional array
ultrasonic sensor moves, testing data for the same defect is
obtained at each testing position. A maximum value of the obtained
testing data is displayed as testing data. With the ultrasonic
imaging apparatus according to the present embodiment, therefore,
the display unit 103X is provided with a processing switching unit
as means for selecting processing in the computer 102XA. This
processing switching unit selects software processing, and
therefore is provided as a switch or button 103XL in the display
unit 103X. The processing switching unit 103XL switches between the
conventional testing mode and the summation (averaging) processing
mode.
[0206] Operation of the two-dimensional array ultrasonic sensor
used for the three-dimensional ultrasonic imaging apparatus
according to the present embodiment will be described below with
reference to FIG. 23.
[0207] FIG. 23 illustrates operation of the two-dimensional array
ultrasonic sensor used for the three-dimensional ultrasonic imaging
apparatus according to the fourth embodiment of the present
invention.
[0208] As mentioned above, the array ultrasonic sensor 101X is
composed of a plurality of piezoelectric elements 104X. When each
of the piezoelectric elements 104X is vibrated due to piezoelectric
effect by an electric signal 201X received from the
transmitter/receiver 102X, the array ultrasonic sensor 101X
transmits an ultrasonic wave 108X. The electric signal 201X
supplied to each piezoelectric element drives it in relation to a
time delay given from the delay time controller. Wave fronts of the
ultrasonic waves transmitted by the piezoelectric elements mutually
interfere to form one combined wave front in the course of
propagation. The ultrasonic sensor 101X can focus the ultrasonic
waves at a desired depth position as well as control a beam angle
205X of the focused ultrasonic wave.
[0209] FIG. 23 illustrates operation of the two-dimensional array
ultrasonic sensor. FIG. 23 illustrates connections between one row
of a plurality of piezoelectric elements 104X and the
transmitter/receiver 102X in consideration of the legibility.
Actually, all the piezoelectric elements 104X are connected to the
transmitter/receiver 102X. Although FIG. 23 illustrates a matrix
array transducer composed of piezoelectric elements arranged in a
matrix form, any type of two-dimensional array ultrasonic sensor
can be used so long as it can three-dimensionally focus the
ultrasonic waves inside an object under test and
three-dimensionally control the ultrasonic beam angle
.smallcircle..
[0210] With the present embodiment, the focal depth is set in
consideration of plate thickness of the object under test. This
makes it possible to reduce ultrasonic diffusing attenuation which
can be a problem when the synthetic aperture method is applied,
thus enabling testing with high S/N ratio even with a long
propagation distance of the ultrasonic wave. Further, an ultrasonic
beam angle range used for testing is set as a solid angle range
within which the ultrasonic wave can be transmitted and received
with high sensitivity. A step of the ultrasonic beam angle is set
in consideration of a tolerance of the number of delay times that
can be set by the delay time controller 102XB.
[0211] Operation of three-dimensional ultrasonic scanning (volume
scan) by the two-dimensional array in the three-dimensional
ultrasonic imaging apparatus according to the present embodiment
will be described below with reference to FIGS. 24 to 26
[0212] FIGS. 24 to 26 illustrate operation of three-dimensional
ultrasonic scanning (volume scan) by the two-dimensional array in
the three-dimensional ultrasonic imaging apparatus according to the
fourth embodiment of the present invention.
[0213] The two-dimensional array ultrasonic sensor 101X, while
maintaining a constant distance between a reference point (direct
under the center thereof) and a focal point, transmits and receives
ultrasonic waves so as to focus them within the ultrasonic beam
angle range used for testing.
[0214] FIG. 24 illustrates swing scanning. While maintaining a
constant distance to an ultrasonic focal point 301, the ultrasonic
sensor 101X continuously changes an angle .theta. (in angular steps
of .DELTA..theta.) within an angle range 302 in a certain plane in
the three-dimensional space. This process is referred to as
sectorial scanning process. Further, the ultrasonic sensor 101X
performs the sectorial scanning process for an angle .phi. (in
angular steps of .DELTA..phi.) within an angle range 303 such that
a plane is continuously drawn, thus enabling three-dimensional
ultrasonic scanning.
[0215] FIG. 25 illustrates rotation scanning. While maintaining a
constant distance to an ultrasonic focal point 401, the ultrasonic
sensor 101X continuously changes an angle .theta.' (in angular
steps of .DELTA..theta.') within an angle range 402 in a certain
plane in the three-dimensional space. This process is referred to
as sectorial scanning process. Further, the ultrasonic sensor 101X
performs the sectorial scanning process for a rotating angle .phi.'
(at a rotating angular step .DELTA..phi.') within a rotating angle
range 403. The ultrasonic sensor 101X changes the rotating angle
range 403 of .phi.' from 0 to 180 degrees to enable
three-dimensional ultrasonic scanning.
[0216] FIG. 26 illustrates wedged swing scanning. Although a wedge
(shoe) is used by conventional methods to unify the directivity of
ultrasonic waves to a direction in which a defect is easily
detected, the two-dimensional array ultrasonic sensor can also use
a wedge for testing. Similar to swing scanning shown in FIG. 24,
while maintaining a constant distance to an ultrasonic focal point
501, the ultrasonic sensor 101X continuously changes an angle
.theta.'' (in angular steps of .DELTA..theta.'') within an angle
range 502 in a certain plane in the three-dimensional space
(sectorial scanning process). Further, the ultrasonic sensor 101X
performs the sectorial scanning process for an angle .phi.'' (in
angular steps of .DELTA..phi.'') within an angle range 503 such
that a plane is continuously drawn. An optimum three-dimensional
ultrasonic scanning method is selected depending on the
characteristics and size of a defect.
[0217] Processing of three-dimensional testing data in the
three-dimensional ultrasonic imaging apparatus according to the
present embodiment will be described below with reference to FIGS.
27 and 28.
[0218] FIGS. 27 and 28 illustrate processing of three-dimensional
testing data in the three-dimensional ultrasonic imaging apparatus
according to the fourth embodiment of the present invention.
[0219] Three-dimensional testing data shown in FIG. 27 is processed
by the computer 102A. FIG. 27 schematically illustrates detailed
processing of the three-dimensional testing data in the computer
102XA.
[0220] For convenience, FIG. 27 illustrates only testing data on a
desired y-axis cross section in the xyz coordinate system. The
computer 102XA shown in FIG. 22 performs the steps of: combining
waveforms obtained by the piezoelectric elements 104X in relation
to a delay time; performing appropriate interpolation processing of
waveforms for each beam angle of each ultrasonic wave to convert
the waveforms to three-dimensional testing data having voxel format
(a voxel means a three-dimensionally arranged cubic element); and
processing the three-dimensional testing data. However, the
three-dimensional testing data used here represents RF
waveforms.
[0221] If the array ultrasonic sensor 101X is horizontally
displaced by a displacement X from a position of three-dimensional
testing data 600 obtained at the testing start position 101XA, a
positional shift occurs if the storage range of the
three-dimensional testing data remains same. Measurement values by
the displacement detector 106X are used to correct the positional
shift. The three-dimensional testing data is subjected to a
deviation .DELTA. in the X-axis direction, and therefore summation
is performed after shifting by the deviation .DELTA., as shown by
formula (5), where X denotes the displacement of the sensor. G
denotes a voxel address value of three-dimensional processing data
603 and gm denotes a voxel address value of the m-th
three-dimensional testing data. The following formula (5) shows the
voxel address value at the time of summation.
[ Formula 5 ] G ( i , j , k ) = m = 1 m g m ( i - ( m - 1 ) .DELTA.
, j , k ) ( 5 ) ##EQU00003##
[0222] When i<(m-1).DELTA., g.sub.n(i,j,k)=0.
[0223] In order to schematically illustrate detailed processing,
the example of FIG. 27 sums up three different sets of
three-dimensional testing data 600, 601, and 602 to obtain the
three-dimensional processing data 603.
[0224] FIG. 28 illustrates processing described in FIG. 27 together
with actual testing conditions.
[0225] First three-dimensional testing data (1) 701A denotes
three-dimensional testing data obtained at the testing start
position 101XA. Similarly, i-th three-dimensional testing data (i)
701B and m-th three-dimensional testing data (m) 701C are obtained
at testing positions 101XB and 101XC, respectively. A total of m
sets of three-dimensional testing data 701 is obtained.
With the present embodiment, the two-dimensional array ultrasonic
sensor 101X is disposed in parallel with the bottom surface, that
is, an axial direction of a parallel flat plate or pipe. With these
pieces of three-dimensional testing data, a reflected echo 103XI
from the bottom surface is obtained directly under the set position
of the two-dimensional array ultrasonic sensor. If a defect
originates from the bottom side, a defect corner echo 103XK and a
defect tip echo 103XJ are observed.
[0226] When summation (or averaging) of these pieces of
three-dimensional testing data is performed while making a shift by
the number of voxels corresponding to the displacement of the array
ultrasonic sensor, as shown in FIG. 27, three-dimensional
processing data 702 is obtained. At the defect tip echo 103XK and
the defect corner echo 103XJ, only the signal of the defect 110X
selectively remains by the superposition of wave fronts of
ultrasonic waves transmitted from various angles. This process is
based on the same principle as the synthetic aperture method. The
three-dimensional processing data 702 is displayed on the display
unit 103X, and used to check a defect position and evaluate a
defect depth.
[0227] Three-dimensional ultrasonic imaging in the
three-dimensional ultrasonic imaging apparatus according to the
present embodiment will be described below with reference to FIGS.
29 and 30.
[0228] FIGS. 29 and 30 are flow charts illustrating detailed
processing of three-dimensional ultrasonic imaging in the
three-dimensional ultrasonic imaging apparatus according to the
fourth embodiment of the present invention.
[0229] Referring to FIG. 29, the testing process performs the steps
of: setting a testing range, and a focal depth and an ultrasonic
beam angle range of the two-dimensional array ultrasonic sensor in
the transmitter/receiver 102X, and starting testing (step S800);
setting the ultrasonic sensor 101X on an object under test (step
S801); performing three-dimensional ultrasonic scanning (volume
scan) swinging the ultrasonic beam angle (step S802); storing a
waveform obtained at each ultrasonic beam angle in the
transmitter/receiver 102X, and converting the obtained waveforms to
three-dimensional testing data in the computer 102XA (step S803);
and displaying the data on the display unit 103X as
three-dimensional testing data. If testing is not completed for the
entire testing range, the testing process moves the two-dimensional
array ultrasonic sensor by the scanning unit 107X (step S804), and
repeats m times three-dimensional ultrasonic scanning and
conversion to three-dimensional testing data until testing is
completed for the entire testing range (step S805).
[0230] When testing is completed for the entire testing range (from
the testing start position 101XA to the testing end position
101XC), the testing process performs the steps of: summing up (or
averaging) the stored three-dimensional testing data while making a
shift by the displacement of the ultrasonic sensor 101X in the
computer 102XA (step S806); displaying on the display unit 103X the
thus obtained (summed up or averaged) three-dimensional processing
data (processing data 702) (step S807); and terminating testing
(step S808).
[0231] FIG. 30 illustrates a second processing flow of
three-dimensional ultrasonic imaging. The second processing flow
subsequently sums up (or averages) three-dimensional testing data
and displays the data each time three-dimensional testing data is
stored.
[0232] The testing process performs the steps of: setting a testing
range, and a focal depth and an ultrasonic beam angle range of the
two-dimensional array ultrasonic sensor in the transmitter/receiver
102X, and starting testing (step S900); setting the ultrasonic
sensor 101X on an object under test (step S901); performing
three-dimensional ultrasonic scanning (volume scan) swinging the
ultrasonic beam angle (step S902); and storing a waveform obtained
at each ultrasonic beam angle, and converting the obtained
waveforms to three-dimensional testing data in the computer 102XA
(step S903).
[0233] When there are two or more sets of three-dimensional testing
data, the testing process sums up (or averages) the stored
three-dimensional testing data while making a shift by the
displacement of the ultrasonic sensor 101X in the computer 102XA
(step S906), and then displays data on the display unit 103X. If
testing is not completed for the entire testing range, the testing
process moves the array ultrasonic sensor by the scanning unit 107X
(step S904), and repeats m times three-dimensional ultrasonic
scanning (volume scan) and conversion to three-dimensional testing
data until testing is completed for the entire testing range (step
S905).
[0234] When testing is completed for the entire testing range (from
the testing start position 101XA to the testing end position
101XC), the testing process terminates testing (step S908).
[0235] As mentioned above, three-dimensional ultrasonic imaging
according to the present embodiment comprises the steps of:
three-dimensionally scanning the inside of an object under test
while varying the beam angle of the ultrasonic wave transmitted
from the two-dimensional array ultrasonic sensor; sequentially
moving the set position of the two-dimensional array ultrasonic
sensor or changing the transmission/reception position of
ultrasonic waves; and summing up (or averaging) three-dimensional
testing data obtained at each testing position while making a shift
by the displacement of the two-dimensional array ultrasonic sensor
or by the transmission/reception position to attain
three-dimensional imaging. Since three-dimensional processing data
can be configured by superimposing ultrasonic waves transmitted
from various angles, the effect of ultrasonic focus can be obtained
without preparing a number of data processing tables (focal law,
delay time). The present embodiment allows high-resolution
three-dimensional processing data to be obtained at almost all
positions, thus attaining high-accuracy non-destructive
testing.
[0236] Further, the present embodiment restricts ultrasonic
diffusing attenuation which has been a problem of the synthetic
aperture method. Specifically, when an object under test is scanned
by converging ultrasonic waves from the array ultrasonic sensor,
ultrasonic diffusing attenuation can be restricted even with a
thick object under test or a long ultrasonic propagation distance.
Accordingly, the S/N ratio of three-dimensional testing data can be
improved. Similarly, the process of summation (or averaging) of
three-dimensional testing data can reduce electrical noise and
other random noise. This process also improves the S/N ratio of
three-dimensional testing data. The present embodiment enables
collective three-dimensional imaging over a wide testing range
based on high resolution and high S/N ratio three-dimensional
testing data and allows images to be handled as one piece of
three-dimensional testing data by using a two-dimensional array
ultrasonic sensor. The present embodiment only utilizes one set of
data processing table (focal law) and is also applicable to thick
objects and high-attenuation materials.
[0237] Configuration and operation of a three-dimensional
ultrasonic imaging apparatus according to a fifth embodiment of the
present invention will be described below with reference to FIGS.
31 and 32. The three-dimensional ultrasonic imaging apparatus
according to the present embodiment is the same as that shown in
FIG. 22.
[0238] FIG. 31 illustrates processing of three-dimensional testing
data in the three-dimensional ultrasonic imaging apparatus
according to the fifth embodiment of the present invention. FIG. 32
is a flow chart illustrating detailed processing of
three-dimensional ultrasonic imaging in the three-dimensional
ultrasonic imaging apparatus according to the fifth embodiment of
the present invention.
[0239] The present embodiment shown in FIG. 31 differs from the
fourth embodiment of FIG. 28 in that the present embodiment feeds
the two-dimensional array ultrasonic sensor also in the y-axis
direction, i.e., in a posterior direction of the paper, and
therefore is used for a wider testing range. Two-dimensional
scanning methods employing a mechanical scanning unit include
zigzag scanning and comb scanning. With comb scanning, the array is
fed in one axial direction, returned to home position, moved in
another axial direction by a scanning pitch, and fed again in the
one axial direction.
[0240] First three-dimensional testing data (1,1) 1001A denotes
three-dimensional testing data obtained at the testing start
position 101XA. Similarly, i.times.j-th three-dimensional testing
data (i,j) 1001B and m.times.n-th three-dimensional testing data
(m.times.n) 1001C are obtained at testing positions 101XB and
101XC, respectively. A total of m.times.n sets of three-dimensional
testing data 1001 is obtained.
[0241] With these pieces of three-dimensional testing data, a
reflected echo 103XI from the bottom surface is obtained directly
under the set position of the two-dimensional array ultrasonic
sensor. If a defect originates from the bottom side, a defect
corner echo 103XK and a defect tip echo 103XJ are observed.
[0242] When summation (or averaging) of these pieces of
three-dimensional testing data is performed while making a shift by
the number of voxels corresponding to the displacement and
direction of the array ultrasonic sensor, three-dimensional
processing data 1002 is obtained. At the defect tip echo 103XK and
the defect corner echo 103XJ, only the signal of the defect 110X
selectively remains by the superposition of wave fronts of
ultrasonic waves three-dimensionally transmitted from various
angles. This process is based on the same principle as the
synthetic aperture method. The three-dimensional processing data
1002 is displayed on the display unit 103X, and used to check a
defect position and evaluate a defect depth.
[0243] Detailed processing of three-dimensional ultrasonic imaging
will be described below with reference to FIG. 32.
[0244] The testing process performs the steps of: setting a testing
range, and a focal depth and an ultrasonic beam angle range of the
two-dimensional array ultrasonic sensor in the transmitter/receiver
102X, and starting testing (step S1100X); setting the ultrasonic
sensor 101X on an object under test (step S1101X); performing
three-dimensional ultrasonic scanning (volume scan) swinging the
ultrasonic beam angle (step S1102X); storing a waveform obtained at
each ultrasonic beam angle in the transmitter/receiver 102X, and
converting the obtained waveforms to three-dimensional testing data
in the computer 102XA (step S1103X); and displaying the data on the
display unit 103X as three-dimensional testing data.
[0245] If testing is not completed for the entire testing range,
the testing process moves the array ultrasonic sensor by the
scanning unit 107X (step S1104X), and repeats m.times.n times
three-dimensional ultrasonic scanning and conversion to
three-dimensional testing data until testing is completed for the
entire testing range (step S1105X).
[0246] When testing is completed for the entire testing range (from
the testing start position 101XA to the testing end position
101XC), the testing process sums up (or averages) the stored
three-dimensional testing data while making a shift by the
displacement of the ultrasonic sensor 101X in the computer 102XA
(step S1106X).
[0247] The testing process displays on the display unit 103X the
thus obtained (summed up or averaged) three-dimensional processing
data (processing data 1002) (step S1107X), and terminates testing
(step S1108X).
[0248] As mentioned above, three-dimensional ultrasonic imaging
according to the present embodiment also comprises the steps of:
three-dimensionally scanning the inside of an object under test
while varying the beam angle of the ultrasonic wave transmitted
from the two-dimensional array ultrasonic sensor; sequentially
moving the set position of the two-dimensional array ultrasonic
sensor or changing the transmission/reception position of
ultrasonic waves; and summing up (or averaging) three-dimensional
testing data obtained at each testing position while making a shift
by the displacement of the two-dimensional array ultrasonic sensor
or by the transmission/reception position to attain
three-dimensional imaging. Since three-dimensional processing data
can be configured by superimposing ultrasonic waves transmitted
from various angles, the effect of ultrasonic focus can be obtained
without preparing a number of data processing tables (focal law,
delay time). The present embodiment allows high-resolution
three-dimensional processing data to be obtained at almost all
positions, thus attaining high-accuracy non-destructive
testing.
[0249] Further, the present embodiment restricts ultrasonic
diffusing attenuation which has been a problem of the synthetic
aperture method. Specifically, when an object under test is scanned
by converging ultrasonic waves from the array ultrasonic sensor,
ultrasonic diffusing attenuation can be restricted even with a
thick object under test or a long ultrasonic propagation distance.
Accordingly, the S/N ratio of three-dimensional testing data can be
improved. Similarly, the process of summation (or averaging) of
three-dimensional testing data can reduce electrical noise and
other random noise. This process also improves the S/N ratio of
three-dimensional testing data. The present embodiment enables
collective three-dimensional imaging over a wide testing range
based on high resolution and high S/N ratio three-dimensional
testing data and allows images to be handled as one piece of
three-dimensional testing data by using a two-dimensional array
ultrasonic sensor. The present embodiment only utilizes one set of
data processing table (focal law) and is also applicable to thick
objects and high-attenuation materials.
[0250] Configuration and operation of a three-dimensional
ultrasonic imaging apparatus according to a sixth embodiment of the
present invention will be described below with reference to FIGS.
33 and 34. The three-dimensional ultrasonic imaging apparatus
according to the present embodiment is the same as that shown in
FIG. 22.
[0251] FIG. 33 illustrates processing of three-dimensional testing
data in the three-dimensional ultrasonic imaging apparatus
according to the sixth embodiment of the present invention. FIG. 34
is a flow chart illustrating detailed processing of
three-dimensional ultrasonic imaging in the three-dimensional
ultrasonic imaging apparatus according to the sixth embodiment of
the present invention.
[0252] The present embodiment shown in FIG. 33 applies an object
under test having a curved surface like a circumference of a pipe
or having a complicated shape while the fourth embodiment of FIG.
28 and the fifth embodiment of FIG. 31 apply an object under test
having a planar shape.
[0253] Referring to FIG. 33, with an object under test
1200.times.having a curved shape, first three-dimensional testing
data (1) 1201XA denotes three-dimensional testing data measured at
the testing start position 101XA. Similarly, i-th three-dimensional
testing data (i) 1201XB and m-th three-dimensional testing data (m)
1201XC are measured at testing positions 101XB and 101XC,
respectively. When three-dimensional ultrasonic scanning (volume
scan) is performed at each position, a total of m sets of
three-dimensional testing data 1201X is obtained. The present
embodiment assumes an object under test having a curved shape such
as a pipe. Therefore, since the surface on which the array
ultrasonic sensor 101X is disposed is almost in parallel with the
bottom surface, an echo 103XI from the bottom surface is obtained
directly under the set position of the array ultrasonic sensor
101X. If a defect originates from the bottom side, a defect corner
echo 1202XA and a defect tip echo 1202XB are observed corresponding
to respective defect position 1202X.
[0254] The testing process sums up (or averages) these pieces of
three-dimensional testing data while making a shift by the number
of pixels corresponding to the displacement of the two-dimensional
array ultrasonic sensor. The present embodiment differs from the
first and second embodiments in that the object under test has a
curved surface and therefore that the effect of inclination by this
shape needs to be corrected when processing three-dimensional
testing data. The present embodiment, therefore, is provided with
premeasured data regarding the surface shape of the object under
test or with a function to measure the inclination of the
two-dimensional array ultrasonic sensor in the displacement
detection unit to correct the inclination at the time of summation
(or averaging) of three-dimensional testing data. Specifically, the
computer shifts three-dimensional testing data by the displacement
of the center position of the array ultrasonic sensor from the
testing start position, rotates the data by the rotation angle from
the testing start position, and performs summation (or averaging)
to obtain three-dimensional testing data 1203X.
[0255] The computer corrects the inclination of each voxel to
adjust mutual positions of voxels through appropriate supplementary
processing as preprocessing, and then performs summation (or
averaging). With the three-dimensional testing data 1203X, at a
defect corner echo 1202XA and a defect tip echo 1202XB, only the
signal at a real defect position selectively remains by the
superposition of wave fronts of ultrasonic waves
three-dimensionally transmitted from various angles. The
three-dimensional testing data 1203X is used to check a defect
position and evaluate a defect depth. Even for a complicated
surface shape, three-dimensional processing data can be created by
performing the above-mentioned processing.
[0256] Detailed processing of three-dimensional ultrasonic imaging
will be described below with reference to FIG. 34.
[0257] The testing process performs the steps of: setting a testing
range, and a focal depth and an ultrasonic beam angle range of the
two-dimensional array ultrasonic sensor, and starting testing (step
S1400); setting the two-dimensional ultrasonic sensor to an object
under test (S1401); performing three-dimensional ultrasonic
scanning (volume scan) (S1402); storing a waveform obtained at each
ultrasonic beam angle; and converting the obtained waveforms to
three-dimensional testing data in the computer (step S1403).
[0258] If testing is not completed for the entire testing range,
the testing process moves the two-dimensional array ultrasonic
sensor along the surface of the object under test by the scanning
unit (step S1404), and repeats m times three-dimensional ultrasonic
scanning and conversion to three-dimensional testing data until
testing is completed for the entire testing range (step S1405).
[0259] When testing is completed for entire testing range, the
testing process performs the steps of: shifting each piece of
three-dimensional testing data stored in the computer by the
displacement of the two-dimensional array ultrasonic sensor from
the testing start position, then rotating the data by the
inclination angle from the testing start position, and then
performing summation (or averaging) (step S1406); displaying the
result on the display unit (step S1407); and terminating testing
(step S1408).
[0260] As mentioned above, three-dimensional ultrasonic imaging
according to the present embodiment also comprises the steps of:
three-dimensionally scanning the inside of an object under test
while varying the beam angle of the ultrasonic wave transmitted
from the two-dimensional array ultrasonic sensor; sequentially
moving the set position of the two-dimensional array ultrasonic
sensor or changing the transmission/reception position of
ultrasonic waves; and summing up (or averaging) three-dimensional
testing data obtained at each testing position while making a shift
by the displacement of the two-dimensional array ultrasonic sensor
or by the transmission/reception position to attain
three-dimensional imaging. Since three-dimensional processing data
can be configured by superimposing ultrasonic waves transmitted
from various angles, the effect of ultrasonic focus can be obtained
without preparing a number of data processing tables (focal law,
delay time). The present embodiment allows high-resolution
three-dimensional processing data to be obtained at almost all
positions, thus attaining high-accuracy non-destructive
testing.
[0261] Further, the present embodiment restricts ultrasonic
diffusing attenuation which has been a problem of the synthetic
aperture method. Specifically, when an object under test is scanned
by converging ultrasonic waves from the array ultrasonic sensor,
ultrasonic diffusing attenuation can be restricted even with a
thick object under test or a long ultrasonic propagation distance.
Accordingly, the S/N ratio of three-dimensional testing data can be
improved. Similarly, the process of summation (or averaging) of
three-dimensional testing data can reduce electrical noise and
other random noise. This process also improves the S/N ratio of
three-dimensional testing data. The present embodiment enables
collective three-dimensional imaging over a wide testing range
based on high resolution and high S/N ratio three-dimensional
testing data and allows images to be handled as one piece of
three-dimensional testing data by using a two-dimensional array
ultrasonic sensor. The present embodiment only utilizes one set of
data processing table (focal law) and is also applicable to thick
objects and high-attenuation materials.
[0262] Configuration and operation of a three-dimensional
ultrasonic testing apparatus according to a seventh embodiment of
the present invention will be described below with reference to
FIGS. 35 to 46.
[0263] First of all, the configuration of the three-dimensional
ultrasonic testing apparatus according to the present embodiment
will be described below with reference to FIG. 35.
[0264] FIG. 35 is a block diagram illustrating a configuration of
the three-dimensional ultrasonic testing apparatus according to the
seventh embodiment of the present invention.
[0265] The three-dimensional ultrasonic testing apparatus according
to the present embodiment is composed of an array ultrasonic sensor
101Z configured to transmit an ultrasonic wave to an object under
test 100, a transmitter/receiver 102Z, and a display unit 103Z
configured to display receive signals and testing images.
[0266] The array ultrasonic sensor 101Z is basically composed of a
plurality of piezoelectric elements 104Z, each being able to
transmit and receive an ultrasonic wave as shown in FIG. 35. The
array ultrasonic sensor 101Z is disposed on a testing surface of
the object under test 100. The array ultrasonic sensor 101Z
transmits an ultrasonic beam 105Z with a drive signal supplied from
the transmitter/receiver 102Z, propagates the ultrasonic beam 105Z
in the object under test 100, detects a reflected wave generated by
the object under test 100, and feeds a receive signal to the
transmitter/receiver 102Z as needed.
[0267] The transmitter/receiver 102Z includes a computer 102ZA, a
delay time controller 102ZB1, a pulser 102ZC, a receiver 102ZD, and
data storage 102ZE to transmit and receive an ultrasonic wave by
using the array ultrasonic sensor 101Z. In the transmitter/receiver
102Z, the pulser 102ZC supplies a drive signal to the array
ultrasonic sensor 101Z, and the receiver 102ZD processes a receive
signal received from the array ultrasonic sensor 101Z.
[0268] The computer 102ZA basically includes a central processing
unit (CPU) 102ZA1, a random access memory (RAM) 102ZA2, a read-only
memory (ROM) 102ZA3, and an external memory 102ZA4. The ROM 102ZA3
contains a program for controlling the CPU 102ZA1 written thereto.
The CPU 102ZA1, according to the program, performs operations while
reading necessary external data from the data storage 102ZE and
exchanging data with the RAM 102ZA2 and the external memory 102ZA4,
and outputs processed data to the data storage 102ZE.
[0269] The CPU 102ZA1 controls the delay time controller 102ZB, the
pulser 102ZC, and the receiver 102ZD to perform necessary
operations. The delay time controller 102ZB controls both the
timing of drive signal output from the pulser 102ZC and the timing
of receive signal input to the receiver 102ZD to attain operations
of the array ultrasonic sensor 101Z employing the phased array
method.
[0270] The array ultrasonic sensor 101Z employing the phased array
method controls a focal depth 107Z and a beam angle 106Z of the
ultrasonic beam 105Z which are formed by combining ultrasonic waves
transmitted from each piezoelectric element of the array ultrasonic
sensor 101Z in relation to a delay time, and receives a reflected
ultrasonic wave. The receiver 102ZD supplies a receive signal to
the data storage 102ZE. The data storage 102ZE processes the
supplied receive signal, stores it as storage data, and at the same
time feeds it to the computer 102ZA. The computer 102ZA performs
the steps of: combining waveforms obtained by the piezoelectric
elements in relation to a delay time; performing appropriate
interpolation processing of waveforms for each beam angle of each
ultrasonic wave to create two-dimensional testing data in units of
a two-dimensional square lattice as represented by the pixel format
as well as three-dimensional testing data in units of a
three-dimensional cubic lattice as represented by the voxel format;
imaging these pieces of data; and displaying them on the display
unit 103Z.
[0271] The display unit 103Z includes a two-dimensional display
screen 103ZB for displaying two-dimensional testing data, a
three-dimensional display screen 103ZC for displaying
three-dimensional testing data, and a waveform display screen 103ZA
for displaying a waveform signal of each piezoelectric element.
FIG. 35 illustrates one display unit 103Z. However, the waveform
display screen 103ZA, the two-dimensional display screen 103ZB, and
the three-dimensional display screen 103ZC may be displayed
separately by a plurality of display units.
[0272] Exemplary display of the three-dimensional display screen
103C in the three-dimensional ultrasonic testing apparatus
according to the present embodiment will be described below with
reference to FIG. 36.
[0273] FIG. 36 illustrates exemplary display of the
three-dimensional display screen in the three-dimensional
ultrasonic testing apparatus according to the seventh embodiment of
the present invention.
[0274] The three-dimensional display screen 103CZ on the display
unit 103Z displays three-dimensional testing data 201Z, as shown in
FIG. 36. The three-dimensional display screen 103CZ can display the
data in a desired display size from a desired viewpoint by an input
from a mouse 102ZF or a keyboard 102ZG connected to the computer
102ZA. In this case, an inspector can numerically input a scale of
enlargement for changing the display size from the keyboard 102ZG.
Although the display color and transparency are given in units of a
voxel lattice, they can be changed in relation to reflection
intensity input from the mouse 102ZF and the keyboard 102ZG. Since
a plurality of display color patterns are provided, an inspector
can select one according to his or her application.
[0275] These three-dimensional drawing algorithms have been
attained, for example, in libraries as represented by OpenGL (a
registered trademark) and DirectX (a registered trademark) which
are industry-wide standard graphics application programming
interfaces (Graphics APIs). If necessary information such as the
shape, viewpoint, and display position of an object to be displayed
is given by using these Graphics APIs in a program, a
three-dimensional shape can be easily drawn with a desired
viewpoint, colors, transparency, and size at a desired position on
the display unit.
[0276] The three-dimensional display screen 103ZC displays
three-dimensional shape data 202Z representing the shape of an
object under test 100 together with the three-dimensional testing
data 201Z thereof. The three-dimensional shape data 202Z is read
from the outside of the computer 102ZA. In particular, if CAD data
of the object under test 100 exists, this data can be read and
displayed. The format of CAD data allows it to be input and output
by commercial CAD software. For example, the STL (an abbreviation
of Stereo Lithography or Standard Triangulated Language) format is
used, which can be read and output by many CAD software products.
The STL format is a representation of a surface of an object with a
set of a number of triangles. A planar normal vector and coordinate
values of three apexes of these triangles are stored in a STL file.
Drawing a plurality of straight lines and triangles makes it easier
to display three-dimensional shape data 202Z from an STL format
file by using Graphics API. Three-dimensional shape data can be
displayed only with outlines as shown in FIG. 36, opaquely with
outer surfaces filled, or half-transparently. These display modes
can be easily attained by changing the transparency value given to
drawing functions implemented in Graphics API when drawing
triangles. Even if the three-dimensional shape data 202Z overlaps
with the three-dimensional testing data 201Z, these display modes
make the data legible for an inspector. Further, the
three-dimensional shape data 202Z can be shown or hidden as
required.
[0277] Although not shown, a plurality of pieces of
three-dimensional shape data 202Z can be simultaneously displayed
on the three-dimensional display screen 103ZC.
[0278] A selected three-dimensional shape data 202Z can be
displayed from a desired viewpoint, at a desired position, and in a
desired size independently from the three-dimensional testing data
201Z by an input from the mouse 102ZF or the keyboard 102ZG
connected to the computer 102ZA.
[0279] The following describes sizing of a crack present inside an
object under test from testing images obtained by the phased array
method by using three-dimensional ultrasonic testing according to
the present embodiment with reference to FIGS. 37 to 46.
[0280] First of all, a three-dimensional scanning method in the
three-dimensional ultrasonic testing apparatus according to the
present embodiment will be described below with reference to FIGS.
37A to 37D.
[0281] FIGS. 37A to 37D illustrate an exemplary three-dimensional
scanning method in the three-dimensional ultrasonic testing
apparatus according to the seventh embodiment of the present
invention.
[0282] FIGS. 37A to 37D illustrate sizing of a crack 303Z
originating from a portion 303ZD on the bottom surface of a plate
302Z by using the three-dimensional phased array method, one of
three-dimensional ultrasonic testing methods.
[0283] Although metal is mainly assumed as the plate 302Z, this
example is applicable to diverse materials such as resin. The crack
303Z branches off and has ends 303ZA, 303ZB, and 303ZC. FIG. 37A is
a bird's-eye view of the crack 303Z, FIG. 37B is a top view
thereof, and FIGS. 37C and 37D are side views thereof. Although
this example assumes that the crack 303Z is like a SCC (stress
corrosion crack) which branches off, the crack does not necessarily
branch off.
[0284] As shown in FIG. 37A, the array ultrasonic sensor 101Z is
disposed on a testing surface 306Z preferable to test the crack
303Z through an appropriate couplant (an ultrasonic propagation
medium). The array ultrasonic sensor 101Z may be either for
transverse wave generation or longitudinal wave generation, and an
appropriate wedge is disposed between the array ultrasonic sensor
101Z and the testing surface 306Z. For example, an ultrasonic
sensor for longitudinal wave generation is disposed with a wedge to
transmit a transverse wave to the plate 302Z.
[0285] Although a three-dimensional scanning process can be set in
any desired way with a delay time pattern controlled by the delay
time controller 102ZB1 (FIG. 35), the following describes a
scanning process with which a two-dimensional sectorial plane is
rotated by 180 degrees (hereinafter referred to as sectorial
rotation scanning process).
[0286] The sectorial rotation scanning process rotates a
two-dimensional sectorial plane used in the conventional sectorial
scanning process around the center axis of the sectorial in
appropriate angular steps only by changing the delay time. The
sectorial rotation scanning process makes it possible to
three-dimensionally scan the inside of an object under test without
moving the array ultrasonic sensor 101Z.
[0287] FIG. 37A illustrates a state in which a sectorial plane is
being rotated in the direction shown by an arrow R1, and a
sectorial group 301 is obtained as storage data. FIG. 37B
illustrates positions of a plurality of sectorial planes with chain
lines when viewed from the top. Although FIG. 37B illustrates 24
sectorial planes in rotational angular steps of 7.5 degrees, FIG.
37A illustrates several out of the 24 sectorial planes in
consideration of the legibility. The number of ultrasonic beams
105Z and a focal depth 107Z composing a sectorial, and a rotational
angular step of the sectorial are set in consideration of the size
of the crack 303Z under assumption and the required spatial
resolution.
[0288] An exemplary two-dimensional display screen of a testing
result obtained by the three-dimensional scanning process in the
three-dimensional ultrasonic testing apparatus according to the
present embodiment will be described below with reference to FIG.
38.
[0289] FIG. 38 illustrates an exemplary two-dimensional display
screen of a testing result obtained by the three-dimensional
scanning process in the three-dimensional ultrasonic testing
apparatus according to the seventh embodiment of the present
invention.
[0290] Each sectorial plane of the sectorial group 301Z shown in
FIG. 37 can be displayed in the two-dimensional display screen
103ZB in any desired way by specifying a sectorial plane. FIG. 38
illustrates an exemplary two-dimensional display screen 103ZB
displaying a sectorial plane 404Z at a cross-sectional position
305Z shown in FIG. 37B. Dotted lines 405Z denote lines projected
onto the sectorial plane 404Z of the crack 303Z, and are shown to
make it easier to understand the present embodiment.
[0291] Since the sectorial plane 404Z includes an incidence point
406Z, the originating portion 303ZD of the crack 303Z, and an end
portion 303ZA thereof, as shown in FIG. 38, an echo 403ZD caused by
the reflection at the originating portion 303ZD and an echo 403ZA
caused by the reflection at the end portion 303ZA are shown. Echoes
caused by the reflection at other end portions are not shown. A
bottom surface echo 403ZE caused by the reflection on the bottom
surface of the plate 302Z directly below the incidence point 406Z
is shown. Profile lines 402Z shown in FIG. 38 are profile lines of
the plate 302Z. These lines are calculated from CAD data of the
plate 302Z read from the outside and displayed on the
two-dimensional display screen 103ZB together with a testing
result.
[0292] An exemplary three-dimensional display screen of a testing
result obtained by the three-dimensional scanning process in the
three-dimensional ultrasonic testing apparatus according to the
present embodiment will be described below with reference to FIG.
39.
[0293] FIG. 39 illustrates an exemplary three-dimensional display
screen of the testing result obtained by the three-dimensional
scanning process in the three-dimensional ultrasonic testing
apparatus according to the seventh embodiment of the present
invention.
[0294] FIG. 39 illustrates exemplary three-dimensional testing
data, created from the storage data obtained by the sectorial
rotation scanning process, displayed on the three-dimensional
display screen 103ZC. Dotted lines 505Z denote a three-dimensional
shape of the crack 303Z, and are shown to make it easier to
understand the present embodiment.
[0295] Since the storage data used here is composed of a plurality
of sectorial planes including the end portions 303ZA, 303ZB, and
303ZC, and the originating portion 303ZD of the crack 303Z shown in
FIG. 37, or a plurality of sectorial planes passing through the
vicinity thereof. Therefore, the three-dimensional display screen
103CZ displays echoes 503ZA, 503ZB, 503ZC, and 503ZD caused by
ultrasonic waves reflected by the end portions 303ZA, 303ZB, and
303ZC, and the originating portion 303ZD, respectively. Similarly
to FIG. 38, the screen 103CZ also displays a bottom surface echo
503ZE. The screen 103CZ further displays the CAD data 501Z of the
array ultrasonic sensor 101Z and the CAD data 502Z of the plate
302Z read from the outside together with a testing result.
[0296] The two-dimensional phased array method must locate a
plurality of echo positions while checking each individual
sectorial image as shown in FIG. 38. On the other hand, the
three-dimensional phased array method can check a plurality of
echoes at one time from the three-dimensional images as shown in
FIG. 39, thus allowing testing procedures to be performed
efficiently and quickly.
[0297] Another three-dimensional scanning process in the
three-dimensional ultrasonic testing apparatus according to the
present embodiment will be described below with reference to FIG.
40.
[0298] FIG. 40 illustrates another three-dimensional scanning
process in the three-dimensional ultrasonic testing apparatus
according to the seventh embodiment of the present invention.
[0299] FIG. 40 illustrates a typical three-dimensional scanning
process other than the sectorial rotation scanning process, with
which data is gathered by swinging a sectorial plane like a folding
fan (hereinafter referred to as sectorial swing scanning). FIG. 40
illustrates a state where the crack 303Z is tested with the
sectorial swing scanning process. The array ultrasonic sensor 101Z
is disposed in the same way as the above-mentioned sectorial
rotation scanning process.
[0300] The sectorial swing scanning process rotates a sectorial
plane used in the conventional sectorial scanning process in the
direction perpendicular thereto centering on the ultrasonic
incidence point in appropriate angular steps based on a delay time
setup. The sectorial swing scanning process also makes it possible
to three-dimensionally scan the inside of an object under test
without moving the array ultrasonic sensor 101Z.
[0301] FIG. 40 illustrates a state where the sectorial plane is
swung in the direction shown by an arrow 602Z to obtain a sectorial
group 601Z as storage data. The number of ultrasonic beams 105Z and
a focal depth 107Z composing a sectorial, and a swing angular step
of the sectorial are set in consideration of the size of the crack
303Z under assumption and the required spatial resolution.
[0302] A method for sizing a crack by using three-dimensional
testing data obtained by the three-dimensional scanning process in
the three-dimensional ultrasonic testing apparatus according to the
present embodiment will be described below with reference to FIGS.
41 to 46.
[0303] FIGS. 41 and 42 are flow charts illustrating detailed
processing of the crack sizing method in the three-dimensional
ultrasonic testing apparatus according to the seventh embodiment of
the present invention. FIG. 43 illustrates a method for selecting a
point on the three-dimensional display screen in the
three-dimensional ultrasonic testing apparatus according to the
seventh embodiment of the present invention. FIGS. 44A and 44B
illustrate a method for selecting a point having a maximum value of
echoes on the three-dimensional display screen in the
three-dimensional ultrasonic testing apparatus according to the
seventh embodiment of the present invention. FIG. 45 illustrates an
exemplary linear three-dimensional scale displayed on the
three-dimensional display screen in the three-dimensional
ultrasonic testing apparatus according to the seventh embodiment of
the present invention.
[0304] First of all, in step S100 of FIG. 41, the operator
specifies a first cubic region containing a echo caused by the
reflection at the crack originating portion D on the
three-dimensional display screen.
[0305] A method for selecting a point on the three-dimensional
display screen in the three-dimensional ultrasonic testing
apparatus according to the present embodiment will be described
below with reference to FIG. 43.
[0306] FIG. 43 illustrates exemplary three-dimensional testing data
of the plate 302Z containing the crack 303Z displayed on the
three-dimensional display screen 103ZC. Echoes displayed and CAD
data are the same as those shown in FIG. 39.
[0307] The following describes a process for measuring the distance
from the originating portion 303ZD of the crack 303Z to the end
portion 303ZA thereof at which the crack 303Z progresses most. A
crack distance measurement mode is activated by clicking a button
on the three-dimensional display screen 103ZC with a mouse
103ZF.
[0308] In step S100 of FIG. 41, the operator specifies a first
cubic region 902Z containing an echo 503DZ caused by the reflection
at the originating portion 303ZD on the three-dimensional display
screen 103ZC.
[0309] Detailed processing of step S100 of FIG. 41 will be
described with reference to the flow chart of FIG. 42, and FIGS.
44A and 44B.
[0310] In step S101 of FIG. 42, the inspector specifies a point
1001Z on the three-dimensional display screen displayed in a
certain viewing direction with the mouse 102ZF (FIG. 35), as shown
in FIG. 44A. In this case, the position at which the point 1001Z is
specified is set in the vicinity of an echo to be selected, that
is, an echo 503ZD shown in FIG. 44A.
[0311] Similarly, in step S102, the inspector specifies a point
1002Z as a second point with the mouse 102ZF. In this case, the
second point is specified so that a square 1003Z having the first
and second points as opposing corners contains the echo 503ZD.
[0312] When positions of the two points is specified, in step S103,
the computer 102ZA (FIG. 35) determines the cubic region 902Z
composed of the square 1003Z. However, in this stage, since a
spatial position cannot be determined in the direction
perpendicular to the viewing direction, it is set at most anterior
or posterior position of the three-dimensional testing data or at
an intermediate position thereof.
[0313] In step S104, the inspector changes the viewing direction
with the mouse 102ZF. In a state shown in FIG. 43,
three-dimensional shape data 502Z is shown so that the x-z plane
comes to the front. This data can be viewed from the right-hand
side face. Specifically, the operator can change the viewing
direction so that the y-z plane comes to the front by dragging a
vertical edge of the three-dimensional shape data 502Z with the
mouse 102ZF to rotate the data by 90 degrees around the z axis of
the display coordinate system. In this case, instead of the
three-dimensional shape data 502Z, the operator can drag
three-dimensional testing data 503ZA or 503ZE to rotate the data by
90 degrees around the z axis of the display coordinate system. It
is also possible to display a push button set to rotate the data by
90 degrees around the z axis on the three-dimensional display
screen 103ZC beforehand, and click this push button with the mouse
to change the viewing direction.
[0314] In this state, in step S105, the computer 102ZA checks again
whether or not the cubic region 902Z contains the echo 503ZD. The
operator can move the cubic region 902Z in parallel with the mouse
102ZF independently of the three-dimensional testing data.
[0315] In determination in step S105, if the cubic region 902Z does
not contain the echo 503ZD, the operator moves the cubic region
902Z with the mouse 102ZF so that the echo 503ZD is contained in
the cubic region 902Z (step S106).
[0316] In step S104 again, the operator changes the viewing
direction of the three-dimensional display to repeat the same
check. Normally, when the operator repeats this operation once or
twice, the echo 503ZD becomes to be contained in the cubic region
902Z. The first cubic region 902Z is specified with the above
operations.
[0317] Although a three-dimensional region to be specified is a
cube, it may be a rectangular parallelepiped, a sphere, or other
three-dimensional region other than a cube.
[0318] In step S110 of FIG. 41, the computer 102ZA selects a voxel
contained in the first cubic region 902Z.
[0319] In step S115, the computer 102ZA selects a voxel having a
maximum value out of voxels included in first cubic region 902Z. In
step S120, the computer 102ZA displays a voxel 1004Z on the
three-dimensional display screen 103ZC in color that allows it to
be recognized thereon, as shown in FIG. 44B.
[0320] In step S125, the inspector checks whether or not a point is
displayed at a desired position, and if not, repeats steps S100 to
115 again.
[0321] If a point is displayed at a desired position, in step S130,
the computer 102ZA determines this point as a first voxel
position.
[0322] In steps S135 to S160, the inspector and the computer 102ZA
specify a second cubic region 901Z including an echo 503ZA caused
by the reflection at the originating portion 303ZA on the
three-dimensional display screen 103ZC. A method for specifying the
second cubic region 901Z and a method for determining the second
voxel position are the same as the method for specifying the first
cubic region 902Z and the method for determining the first voxel
position, respectively.
[0323] In step S165, the computer 102ZA calculates the distance
between the first and second voxel positions from coordinates
values of the two voxel positions.
[0324] In step S170, the computer 102ZA displays a linear
three-dimensional scale connecting between the first and second
voxel positions on the three-dimensional display screen in color
that allows it to be recognized thereon.
[0325] Specifically, as shown in FIG. 45, the computer 102ZA
displays a linear three-dimensional scale 1101Z connecting between
the first and second voxel positions on the three-dimensional
display screen 103ZC in color that allows it to be recognized
thereon. In this case, a distance L1 between the two points is also
displayed on the display unit 1102Z in the vicinity of the
three-dimensional scale. (For example, the distance between the two
points is displayed as "3 mm" in the figure.)
[0326] The inspector can move both end points 1103ZA and 1103ZD of
the three-dimensional scale 1101Z in parallel in the direction
perpendicular to the viewing direction displayed up to a desired
position, by dragging with the mouse 102ZF the two points. Thus,
the setup position of the three-dimensional scale 1101Z can be
fine-adjusted. The three-dimensional scale 1101Z is also applicable
to measurement of distance between other portions by largely moving
the point 1103ZA or 1103ZD. When the point 1103ZA or 1103ZD is
moved, the straight line connecting the two points changes, and the
numerical value at the display unit 1102Z displaying the distance
between two points also changes accordingly.
[0327] Not only a point corresponding to an echo but also an
ultrasonic incidence point or any point defined in CAD data 501Z
and 502Z can be used as a point for defining the three-dimensional
scale 1101Z. Therefore, it is also possible to measure distance
between two points other than ones defined in voxel data.
[0328] As mentioned above, three-dimensional drawing processing for
this purpose can be easily attained, for example, by utilizing
libraries offered by OpenGL and DirectX (typical Graphics APIs) in
a program.
[0329] As mentioned above, by operating the three-dimensional scale
1101Z on the three-dimensional display screen 103ZC, the inspector
can perform sizing on the crack 303Z as well as measure distance
between various positions without displaying a cross-section of the
three-dimensional testing data. Thus, measurement procedures can be
performed easily and efficiently.
[0330] The following describes display of positional information
with reference to a non-crack position in the three-dimensional
ultrasonic testing apparatus according to the present embodiment
referring to FIGS. 46A and 46B.
[0331] FIGS. 46A and 46B illustrate exemplary display of positional
information with reference to a non-crack position in the
three-dimensional ultrasonic testing apparatus according to the
seventh embodiment of the present invention. FIG. 46A is a top view
of FIG. 45, and FIG. 46B is a side view of FIG. 45.
[0332] In the example shown in FIG. 45, both end points 1103ZA and
1103ZD of a crack are specified as two points specified on the
three-dimensional display unit, and the three-dimensional scale
1101Z is displayed with reference to these points. One of the two
points specified on the three-dimensional display unit can be
specified as a non-crack point.
[0333] As a first example, positional information with reference to
an ultrasonic incidence point may be given as one of the two points
specified on the three-dimensional display unit. A case in which
the point 1103ZA is specified will be described below.
[0334] In this example, an ultrasonic incidence point 1204Z is
specified as one of the two points specified on the
three-dimensional display unit. Although the ultrasonic incidence
point 1204Z can be specified using cube display as described in
FIGS. 42 and 44, a push button named "Ultrasonic incidence point"
is displayed on the three-dimensional display screen 103ZC and this
push button is then clicked with the mouse to specify the
ultrasonic incidence point 1204Z.
[0335] When two points are specified, a distance L2z from the
testing surface 306Z shown in FIG. 46 is calculated and displayed
at an appropriate position at an end of the three-dimensional
display screen 103ZC. It is needless to say that the distance L2z
may be displayed on another screen. This can be easily attained by
calculating a distance between a plane defined in the CAD data 502Z
of the plate 302Z read from the outside and the point 1103ZA.
[0336] Further, when viewed from the direction perpendicular to the
testing surface 306Z, a distance L2xy formed by projecting a
straight line connecting the ultrasonic incidence point 1204Z and
the point 1103ZA onto the testing surface 306Z is calculated. This
distance can also be calculated based on planar geometric
information defined in the CAD data 502Z of the plate 302Z, and
coordinate values of the point 1103ZA and the ultrasonic incidence
point 1204Z.
[0337] An elevation angle .theta.2z and an azimuthal angle
.theta.2xy of the point 1103ZA in a coordinate system having the
ultrasonic incidence point 1204Z as an origin are calculated and
displayed on the three-dimensional display screen 103ZC. Generally,
this coordinates system is such that the normal direction (chain
line) of the testing surface 306Z is set as the z axis. Although
the x and y axes may be set in any desired way in relation to an
object under test, they must be set with reference to an edge or a
lateral face of the object under test or other characteristic
shape.
[0338] Similarly, a distance, an elevation angle, and an azimuthal
angle can be obtained for the other end point 1103ZD of the
three-dimensional scale 1101Z.
[0339] As a second example, positional information with reference
to an end point of the three-dimensional scale 1101Z may be given
as one of the two points specified on the three-dimensional display
unit. A case in which an end point 1206Z of the three-dimensional
scale 1101Z is specified will be described below.
[0340] As one of the two points specified on the three-dimensional
display unit, the end point 1206Z of the CAD data 502Z is
specified. Although the end point 1206Z can be specified using cube
display as described in FIGS. 42 and 44, a push button named "End
point" is displayed on the three-dimensional display screen 103ZC
and this push button is clicked with the mouse. Then, when the
vicinity of a desired end point is specified in the AD data 502Z
shown in FIG. 43 by using cube display, it is also possible to
easily specify the end point 1206Z.
[0341] When two points are specified, distances L3xy and L3z from
the end point 1206Z shown in FIG. 46 are calculated and displayed
at an appropriate position at an end of the three-dimensional
display screen 103ZC. It is needless to say that the distances L3xy
and L3z may be displayed on another screen. This can be easily
attained by calculating a distance between a plane defined in the
CAD data 502Z of the plate 302Z read from the outside and the point
1103ZD.
[0342] An azimuthal angle .theta.3xy of the point 1103ZD in a
coordinate system having the end point 1206Z as an origin is
calculated and displayed on the three-dimensional display screen
103ZC. The elevation angle in this case is 0 degree.
[0343] Further, after the inspector specifies any one end point of
the three-dimensional scale 1101Z, for example, the point 1103ZA,
the inspector specifies the end point by using a button on the
three-dimensional display screen 103ZC. Then a sectorial plane
having the shortest distance to the point 1103ZA (for example, the
plane 404Z) out of a plurality of sectorial planes composing
measurement data is automatically displayed on the two-dimensional
display screen 103ZB.
[0344] Another configuration of a three-dimensional ultrasonic
testing apparatus used for the present embodiment of the present
invention will be described below with reference to FIG. 47.
[0345] FIG. 47 is a block diagram illustrating another
configuration of the three-dimensional ultrasonic testing apparatus
used for the seventh embodiment of the present invention.
[0346] Although the three-dimensional ultrasonic testing apparatus
shown in FIG. 35 obtains three-dimensional testing data by using
the phased array method, the present invention is also applicable
to three-dimensional testing data obtained by using a method other
than the phased array method, for example, the synthetic aperture
method.
[0347] FIG. 47 illustrates a configuration of the three-dimensional
ultrasonic testing apparatus in a case where three-dimensional
testing data is obtained by using the synthetic aperture
method.
[0348] The three-dimensional ultrasonic testing apparatus according
to the present embodiment includes an array ultrasonic sensor 101Z
configured to transmit an ultrasonic wave to an object under test
100, a transmitter/receiver 102Z, and a display unit 103Z
configured to display a receive signal and a testing image.
[0349] The array ultrasonic sensor 101Z is basically composed of a
plurality of piezoelectric elements 104Z, each being able to
transmit and receive an ultrasonic wave as shown in FIG. 47. The
array ultrasonic sensor 101Z is disposed on a testing surface of
the object under test 100. The array ultrasonic sensor 101Z
transmits an ultrasonic beam 105ZB with a drive signal supplied
from the transmitter/receiver 102Z, propagates the ultrasonic beam
105ZB in the object under test 100, detects a reflected wave
appearing thereon, and feeds a receive signal to the
transmitter/receiver 102Z.
[0350] The respective piezoelectric elements 104Z of the array
ultrasonic sensor 101Z are sequentially driven at necessary timing
by a drive signal supplied from a drive signal controller 102ZB2
through a pulser 102ZC. The plurality of piezoelectric elements
104Z two-dimensionally receive a reflected wave of the ultrasonic
wave generated therefrom. A receive signal is fed to a receiver
102ZD of the transmitter/receiver 102Z. Specifically, the
respective piezoelectric elements 104Z of the array ultrasonic
sensor 101Z receive reflected waves whose number is equal to the
total number of the piezoelectric elements 104Z.
[0351] The signal fed to the receiver 102ZD is sequentially stored
in data storage 102ZE as storage data. Based on the storage data,
the computer 102ZA performs three-dimensional imaging of waveforms
obtained by the piezoelectric elements 104Z by using the synthetic
aperture method, and displays imaging results on the display unit
103Z.
[0352] The computer 102ZA basically includes a CPU 102ZA1, a RAM
102ZA2, a ROM 102ZA3, and an external memory 102ZA4. The ROM 102ZA3
has a program for controlling the CPU 102ZA1 written thereto. The
CPU 102ZA1, according to the program, performs operations while
reading necessary external data from the data storage 102ZE and
exchanging data with the RAM 102ZA2, and outputs processed data to
the data storage 102ZE as required.
[0353] A method for displaying and processing three-dimensional
testing data 201Z generated by the synthetic aperture method by the
computer 102ZA together with three-dimensional shape data 202Z, and
a method for sizing a crack inside an object under test from a
testing image are the same as those described in the
above-mentioned first embodiment. Therefore, descriptions of these
methods are omitted here.
[0354] As mentioned above, by operating the three-dimensional scale
on the three-dimensional display screen, the inspector can size the
crack as well as measure a distance between various positions
without interruptively displaying the three-dimensional testing
data. Thus, measurement procedures can be performed easily and
efficiently.
* * * * *