Measuring and testing – Vibration – By mechanical waves
Reexamination Certificate
2003-03-07
2004-03-02
Williams, Hezron (Department: 2856)
Measuring and testing
Vibration
By mechanical waves
C073S633000, C073S626000, C365S230040, C365S194000, C365S239000, C600S443000, C600S444000, C600S447000
Reexamination Certificate
active
06698291
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ultrasonic inspection apparatus, and more particularly, relates to a digital type ultrasonic inspection apparatus reducing the dead time in the scan operation of a scanner to zero by utilizing large-volume data transfer.
2. Description of the Related Art
A conventional general analog-type ultrasonic inspection apparatus will be explained first referring to
FIG. 3. A
sample or an inspected object
101
is placed in the water of a water tank
102
. The water tank
102
is placed on a measurement stage
103
. A scanner
104
is placed on the water tank
102
. The scanner
104
is attached to the measurement stage
103
. The scanner
104
is comprised of an X-axis scanner
105
, Y-axis scanner
106
and Z-axis scanner
107
. The Z-axis scanner
107
is provided at its bottom with an ultrasonic probe
108
. The tip of the ultrasonic probe
108
faces the sample
101
at the bottom side. The X-axis, Y-axis and Z-axis as axes of the scan operation of the scanner
104
are perpendicular to each other. The operations of the X-axis scanner
105
, Y-axis scanner
106
and Z-axis scanner
107
are controlled by a motor controller
109
. Under the control of the motor controller
109
, the scanner
104
independently scans along the X-axis, Y-axis and Z-axis. The motors of the scanner
104
for the three axes have encoders
110
respectively. The encoders
110
for the X-axis, Y-axis and Z-axis output trigger signals indicating the positional coordinates on the X-axis, Y-axis, and Z-axis by resolutions set in advance.
A pulser/receiver circuit
111
transmits a drive pulse signal to the ultrasonic probe
108
and receives a reflection echo signal from the ultrasonic probe
108
. An analog peak detector
112
extracts the reflection echo signal relating to a desired inspection surface from the reflection echo signal received through a gate circuit and holds the peak value. An A/D conversion circuit
113
converts the analog peak values of the reflection echo signal to digital values while linking them with the trigger signals output from the encoders
110
. A computer
114
is comprised of a CPU
115
, keyboard
116
, and main memory
117
. The computer
114
controls the motor controller
109
. Further, the computer
114
stores the digital peak values of the reflection echo signal in the main memory
117
through a data bus
118
and further displays the peak values on a monitor
119
in accordance with the planar coordinates. The data stored in the main memory
117
is used for various types of data processing. In addition, the pulser/receiver circuit
111
is similarly connected to an oscilloscope
120
.
In the ultrasonic inspection apparatus shown in
FIG. 3
, the X-axis scanner
105
and the Y-axis scanner
106
scan planarly, while the ultrasonic probe
108
transmits an ultrasonic pulse toward the sample
101
based on the drive pulse signal given from the pulser/receiver circuit
111
. The ultrasonic probe
108
receives the reflection echo signal returned from the sample
101
. Using the received reflection echo signal, the analog peak detector
112
holds the peak values of the reflection echo signal near the desired inspection surface. The A/D conversion circuit
113
uses position trigger signals output from the encoders
110
to sample the data. Next, the computer
114
obtains the data, then displays an image based on the obtained signal on the monitor
119
. In this way, a picture of the desired inspection surface in the sample
101
is obtained.
There are two methods as shown in FIG.
2
A and
FIG. 2B
for the X-axis and Y-axis planar scan by the X-axis scanner
105
and Y-axis scanner.
The method of measurement shown in
FIG. 2A
includes the step of having the A/D conversion circuit
113
use the position trigger signals output from the encoders
110
during a two-directional scan to sample data and the step of having the computer
114
display an image of the inspection surface echo signal obtained on the monitor
119
. In this way, a picture of the desired inspection surface of the sample
101
is obtained on the monitor
119
. This measurement method requires that before the feed scan in the Y-direction by the Y-axis scanner
106
is completed and the return scan of the X-direction by the X-axis scanner
105
is started, the transfer of data from the A/D conversion circuit
113
to the computer
114
be completed and the A/D conversion circuit
113
can sample the data during the return scan.
The method of measurement shown in
FIG. 2B
includes the step of having the A/D conversion circuit
113
use the position trigger signals output from the encoders
110
to sample data during the scan in the same direction at all times for the X-direction, and the step of having the computer
114
display an image based on the obtained inspection surface echo signal on the monitor
119
. In this way, a picture of the desired inspection surface of the sample
101
is obtained on the monitor
119
. This measurement method makes it possible to simultaneously perform a feed scan in the Y-direction by the Y-axis scanner
106
and return scan in the X-direction by the X-axis scanner
105
. Further, it requires that, before the start of the next X-axis outgoing scan, the transfer of the data from the A/D conversion circuit
113
to the computer
114
be completed and the A/D conversion circuit
113
can sample data at the time of the next outgoing scan.
The number of the two-directional scans in the X-direction in the scan method of
FIG. 2A
is half that of the number in the scan method of FIG.
2
B. Accordingly, in general, it is known that the scan time in
FIG. 2A
is shorter than the scan time in FIG.
2
B.
As explained above, the analog type ultrasonic inspection apparatus shown in
FIG. 3
can extract the peak values of a reflection echo signal of a desired inspection surface and produce a picture of the peak values. This ultrasonic inspection apparatus, however, requires several analog peak detectors when trying to simultaneously obtain peak values of reflection echo signals of several inspection surfaces. Further, when the ultrasonic inspection apparatus has several analog peak detectors, the problems of variations in the circuit characteristics among the detectors and the detection gate technology for reliably separating the echoes arise.
To solve these problems, a digital type ultrasonic inspection apparatus has been proposed. This digital type ultrasonic inspection apparatus uses a high speed A/D converter to convert the reflection echo signals to digital data and performs the gating and peak detection of the reflection echo signals at the desired positions digitally to instantaneously obtain information of several inspection surfaces.
FIG. 4
shows an example of the digital type ultrasonic inspection apparatus. In
FIG. 4
, components in common with those of the analog type ultrasonic inspection apparatus explained above are assigned the same reference numerals for convenience in explanation. The digital type ultrasonic inspection apparatus has a peak detection program
121
within the memory of the computer
114
instead of the analog peak detector
112
of the analog type ultrasonic inspection apparatus. Further, instead of the A/D conversion circuit
113
, an A/D converter
122
is provided. The A/D converter
122
is comprised of an A/D conversion circuit
122
a
and a memory
122
b.
In the digital type ultrasonic inspection apparatus shown in
FIG. 4
, the A/D converter
122
samples the waveform data of several hundred to several thousand of points from the surface to the bottom of the sample
101
for each position trigger signal output from the encoders
110
. The large number of waveform data sampled is stored in the memory
122
b
. The computer
114
performs the gating of the waveforms and the detection of the peak values of the desired inspection surface for the waveform data stored in the main memory
117
by the peak detection program
121
. And it displays the digital
Hebaru Toshiyuki
Ishijima Makoto
Kawakami Naoya
Miyata Tohru
Takeuchi Ken
Hitachi Kenki FineTech. Co., Ltd.
Mattingly Stanger & Malur, P.C.
Miller Rose M.
Williams Hezron
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