X-ray or gamma ray systems or devices – Electronic circuit – With display or signaling
Reexamination Certificate
2000-10-17
2002-07-30
Kim, Robert H. (Department: 2882)
X-ray or gamma ray systems or devices
Electronic circuit
With display or signaling
C378S062000
Reexamination Certificate
active
06426995
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates in general to radiation inspection systems and methods using the same, and more particularly, to a radiation inspection system and a method using the same allowing visual images to be transmitted sequentially using an electronic shutter.
2. Description of the Related Art
Radiation includes &agr;-rays, &bgr;-rays, &sgr;-rays, X-rays, neutron-rays, etc. which cause electrolytic dissociation in reacting with materials. X-rays are electronic waves whose wavelengths are in the range of 10-0.001 nm, having such optical characteristics as reflection and diffraction, etc. The wavelengths can be exactly measured using a diffraction grating.
X-rays have a capability of transmitting or passing through an object. The rate of transmission varies depending upon materials, density and thickness of the object. An X-ray detection method uses this property of X-rays to detect thickness and position of a defective part in the object from the difference in photosensitive intensity of a film photographed by X-rays.
X-rays show the phenomenon of diffraction when transmitted into an object. An X-ray stress measuring method uses this property of X-rays to calculate stress by transmitting X-rays into the object and measuring from diffracted rays a dimensional variation in the distance between faces of a certain crystal lattice to which stress is applied.
A radiation inspection system is a typical non-destructive test (NDT) system which employs and systemizes the X-ray detection method and the X-ray stress measuring method. X-ray transmission characteristics vary depending upon materials, density and thickness of an object to be inspected, so that the X-rays are reflected into X-ray projecting images. The radiation inspection system converts the X-ray projecting images into visual images. The radiation inspection system performs a non-destructive test on a portion of the object which is invisible from the outside, based on the converted visual images.
FIG. 4
is a perspective view schematically showing a conventional radiation inspection system, and
FIG. 5
is a perspective view partially showing some elements of the system of
FIG. 4
from a different angle. As illustrated, the conventional radiation inspection system is comprised of an X-Y table
57
on which an object
53
to be inspected by NDT rests, an X-ray electronic tube
51
for generating X-rays and projecting the X-rays into the object
53
, and an image intensifier
55
for forming visual images from the X-rays having passed through the object
53
. The radiation inspection system is further comprised of an image selection unit
60
for selecting desired visual images among visual images formed by the image intensifier
55
and a charge coupled device (CCD) camera
65
for photographing the selected images and outputting them to an image sensor(not shown).
Between the X-ray electronic tube
51
and the image intensifier
55
is disposed the X-Y table
57
on which the object
53
rests and which is movable in X-Y directions. The image intensifier
55
is disposed on a transmission path of he X-rays generated by the X-ray electronic tube
51
. On the lower face of the image intensifier
55
is provided a visual image part
56
on which the visual images formed through the image intensifier
55
are projected.
The image selection unit
60
is disposed along the transmission path of the X-rays under the visual image part
56
, and comprises a primary galvanometer
61
and a secondary galvanometer
62
. The primary galvanometer
61
has a rotary shaft parallel to the plane of the visual image part
56
and the secondary galvanometer
62
has a rotary shaft perpendicular to the plane of the visual image part
56
. On the one end of the rotary shaft of the primary galvanometer
61
is mounted a primary reflector
63
for selectively reflecting the visual images from the visual image part
56
. On the one end of the rotary shaft of the secondary galvanometer
61
is mounted a secondary reflector
64
for selectively reflecting the visual images reflected by the primary reflector
63
, toward the CCD camera
65
.
The image selection unit
60
further comprises a galvanometer controller
67
for controlling rotational angles of the primary galvanometer
61
and the secondary galvanometer
62
so as to selectively provide the CCD camera
65
with the visual images projected on the visual image part
56
, through a reflection path optically formed by the primary reflector
63
and the secondary reflector
64
.
The primary and secondary galvanometers
61
and
62
have very little moment of inertia, to thereby enable a precise servo control at high speed. Accordingly, the primary and secondary galvanometers
61
and
62
are capable of precisely rotating the primary and secondary reflectors
63
and
64
at high speed so as to reflect visual images on any part of the visual image part
56
.
The conventional radiation inspection system operates n the following manner. The X-ray electronic tube
51
radiates X-rays toward the area to be inspected on the object
53
while being rotated along a circumferential direction at constant speed. Projected images formed by the X-rays having passed through the object
53
are circumferentially projected on the top face of the image intensifier
55
. The projected images on the top face of the image intensifier
55
are converted into visual images through the inside of the image intensifier
55
. The visual images are projected on the visual image part
56
positioned on the lower end of the image intensifier
55
. The visual images projected on the visual image part
56
are selected by the image selection unit
60
and photographed by the CCD camera
65
. The visual images photographed by the CCD camera
65
are synthesized and analyzed by a computer (not shown).
However, the conventional radiation inspection system results in high production cost because of the galvanometers
61
and
62
which are comparatively expensive as an image selection unit
60
for selecting visual images. Additionally, distortion of visual images may be caused by the primary and secondary reflectors
63
and
64
in the course of transferring the visual images to the CCD camera
65
, thereby resulting in lowering a reliability of the inspection result.
To solve the above-described problems, a radiation inspection system has been proposed which provides a plurality of image intensifiers and a plurality of CCD cameras corresponding to the number of projected images formed by the X-rays, so that visual images formed through the image intensifier
55
can be directly transmitted into the respective CCD cameras. The radiation inspection system of this type is advantageous in photographing the visual images promptly and precisely, but it still requires a high cost of production.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a radiation inspection system and a method for using the same allowing visual images to be photographed promptly and precisely, but with a lower cost of production.
In accordance with the present invention, the above and other objects can be achieved by the provision of a radiation inspection system comprising a steering radiation electronic tube for projecting radiation onto an object to be inspected, an image intensifier for converting a plurality of projection images formed by the radiation from the steering radiation electronic tube into visual images, the image intensifier having a visual image part on which the visual images are projected, an electronic shutter having a visual image transmission part for transmitting the visual images projected on the visual image part of the image intensifier in sequence, and a camera for photographing the visual images from the visual image transmission part of the electronic shutter in sequence.
Preferably, electric signals are applied synchronously with formation of the visual images to th
Joo Hyo-nam
Kim Hyeong-cheol
Kim Yong-won
Kim Robert H.
Larson & Taylor PLC
Song Hoon K.
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