Laminography system having a view selector with prism

Details Laminography system having a view selector with prism Laminography system having a view selector with prism

1999-03-03

2001-04-24

Kim, Robert H. (Department: 2882)

X-ray or gamma ray systems or devices

Specific application

Tomography

C378S039000

Reexamination Certificate

active

06222903

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laminography system for obtaining an image of lamina of a test object, thereby inspecting interior of the test object, which are not observed with the naked eye.
2. Description of the Prior Art
Generally, various quality inspections are carried out during the manufacturing of industrial products in order to confirm whether the products are acceptable or not. Among these, a laminography system is utilized for the inspection of certain areas hardly observed with the naked eye, such as solder connections of electronic devices mounted on a printed circuit board, or the like.
Construction and operation of a prior art laminography system is described hereinbelow.
As shown in
FIG. 1
, a laminography system
1
includes a table
10
, an X-ray source
20
, an image intensifier
30
, a view selector
40
, and a camera
50
. X-rays irradiated from the X-ray source
20
rotate along the circumference of the X-ray source
20
with a predetermined speed. Such rotating X-rays are transmitted through a test object E which is loaded on the table
10
. The X-rays transmitted through the test object E produce images on an image projecting plane
32
.
At this time, due to the different positions from which the rotating X-rays are irradiated, the images are projected onto different portions of the image projecting plane
32
as shown in FIG.
2
. The images on the respective portions of the image projecting plane
32
are then interposed on one another, and an image of a lamina is obtained.
Generally, due to the rotation of the X-rays along the circumference of the X-ray source
20
, the image transmitted through the test object E rotates on the image projecting plane in the circumferential direction thereof. Therefore, the images are selected in order by the view selector
40
, and received into the camera
50
.
The above-described view selector
40
guides the images from the respective areas of the image projecting plane
32
into the camera
50
by means of a pair of mirrors. U.S. Pat. Nos. 4,926,452 and 5,594,770 disclose typical examples of such view selector.
According to the view selector of U.S. Pat. No. 4,926,452 as shown in
FIG. 3
, a pair of mirrors
42
′ and
44
′ facing each other are rotated together with the images rotating along the circumference of the image projecting plane
32
, so that the mirrors
42
′ and
44
′ guide the images into the camera
50
. Here, the mirrors
42
′ and
44
′ and images are rotated together at the same speed. Meanwhile,
FIG. 4
shows the view selector of U.S. Pat. No. 5,594,770 in which a pair of mirrors
42
″ and
44
″ are disposed under the image intensifier in such a manner that the mirrors
42
″ and
44
″ can be rotated respectively about an X-axis and an Y-axis. Thus, when the images are moved on the image projecting plane
32
disposed on the image intensifier, the mirrors
42
″ and
44
″ are rotated about the X, and Y-axes so as to select the image of a certain area. Accordingly, as the images on the image projecting plane
32
are reflected on the mirrors
42
″ and
44
″ in subsequent order, the images are sequentially received into the camera
50
. The reference numerals
43
″ and
45
″ in
FIG. 4
denote motors for rotating the mirrors
42
″ and
44
″.
According to the view selector of U.S. Pat. No. 4,926,452, however, the view selector is operated only when the images are moving in the circumferential direction of the image projecting plane. Further, the view selector of that patent has a drawback in that the images at the center portion of the image intensifier can not be easily obtained. The view selector of U.S. Pat. No. 5,594,770 has the possibility of having image distortions due to the fact that the angle of incidence of the X-rays keeps changing in accordance with the different positions of the images.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a laminography system capable of obtaining every image projected on every portion of an image projecting plane without image distortions.
Above-mentioned object is accomplished by a laminography system of the present invention including a table, an X-ray source, an image intensifier, a view selector and a camera. The view selector has a prism for refracting a ray of light, and an adjusting section for adjusting the prism to a position in which image of certain area of an image projecting plane of the image intensifier can be received into the camera.
The adjusting part has a first motor for rotating the prism along the circumferential direction of the image intensifier, and a second motor for rotating the prism in a direction perpendicular with respect to a radial direction of the image intensifier. Additionally, a mirror can be disposed at the position corresponding to the central portion of the image intensifier of the prism so as to refract the image at the central portion of the image intensifier into another camera.
Alternatively, a pair of prisms can be disposed at a lower side of the image intensifier in such a manner that the prisms rotate respectively about an X-axis and an Y-axis. As the adjustment parts, a pair of motors rotate the prisms about X-axis and Y-axis.


REFERENCES:
patent: 4926452 (1990-05-01), Baker et al.
patent: 5259013 (1993-11-01), Kuriyama et al.
patent: 5533087 (1996-07-01), Snoeren
patent: 5594770 (1997-01-01), Bowles et al.
patent: 6038286 (2000-03-01), Wagli et al.
patent: 5-312735 (1993-11-01), None

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