X-ray or gamma ray systems or devices – Specific application – Absorption
Reexamination Certificate
1999-09-02
2001-10-09
Church, Craig E. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Absorption
C378S058000
Reexamination Certificate
active
06301327
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for examining luggage by X-ray scanning, wherein the pieces of luggage to be examined are moved on a conveyor belt into a scanner which contains the X-ray components, i.e., an X-ray unit and a detector unit.
2. Description of the Related Art
Apparatus of the above-described type are known in various configurations. They are used for automatically examining luggage, particularly at airports. For this purpose, the apparatus are integrated into the luggage conveying and handling system of the respective airport. This results in basic requirements concerning dimensions and examination speeds.
In the X-ray scanning method used in connection with the present invention, the X-rays which emanate from an X-ray tube are scattered by the contents of the piece of luggage being examined. This scattered signal is received by a detector and is processed by a subsequently connected electronic unit. The measured spectrum is an indication for the substance contained in the piece of luggage. The measured signal is compared to signals stored in a data bank. If there is a match, an alarm will be given.
There are basically various methods for completely scanning the piece of luggage. In practice, a strip having a width of approximately 5 cm can be scanned in each scanning process. Consequently, when a piece of luggage is large, a plurality of individually scanned strips are used for generating the total picture. This requires a corresponding amount of time.
The piece of luggage is being moved on a conveyor belt. When the X-ray/detector unit is stationary, the piece of luggage must be moved relative to the scanner, for example, in a meander-shaped configuration, between the X-ray tube and the detector in order to carry out scanning with the necessary strip units. For this purpose, the actual conveying unit and the movement of the piece of luggage must be interrupted and changed. This is not acceptable in the case of luggage at airports because each individual piece of luggage would have to be moved, not only in the conveying direction, but also back and forth.
SUMMARY OF THE INVENTION
Therefore, it is the primary object of the present invention to provide a method and an apparatus of the above-described type which meet the requirements with respect to examination speed and examination accuracy without unacceptably hindering the flow of the luggage and which make it possible to have a configuration of the entire apparatus which is as compact as possible.
In accordance with the present invention, it is not the piece of luggage which is moved during the scanning process; rather, the scanner together with the X-ray/detector unit is moved over the piece of luggage which stands still. After each scanning process, the piece of luggage is moved on the conveyor belt in a timed manner and the step of scanning the piece of luggage is repeated.
Consequently, during each movement of the scanner, i.e., the forward movement and the return movement of the scanner, a strip of the piece of luggage is scanned. This process is repeated in dependence on the dimensions of the piece of luggage, so that the strips can then be combined to form the scanned image of the entire piece of luggage. The times during which the piece of luggage stands still are very short because the scanner can be moved very quickly and very accurately over the piece of luggage.
It is basically possible to carry out either a straight movement of the scanner essentially perpendicularly of the conveying direction of the piece of luggage, or a swivelling movement is carried out in the manner of a windshield wiper or along a circular arc. The latter manner of movement has the advantage that the apparatus can have very narrow dimensions. The swivel axis is located either laterally next to the conveyor belt or the axis extends through the center of the conveyor belt.
In accordance with a particularly advantageous feature, the scanning axis, i.e., the axis extending between the X-ray unit and the detector unit, is inclined relative to the plane of the conveyor belt, wherein the inclination exists advantageously transversely of the conveying direction as well as in the conveying direction. This makes it possible to scan even thin objects in the piece of luggage which have been arranged vertically or exactly horizontally relative to the conveying direction in an attempt to prevent detection. This can be achieved in different ways, for example, by inclining the carriage and, thus, a corresponding inclination of the scanner, or by inclining the swivel axis depending on which method is being selected and which device is being used.
In order to operate as quickly and efficiently as possible, a scanning process is carried during each movement of the scanner, i.e., during every forward and backward movement of the scanner over the piece of luggage.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
REFERENCES:
patent: 3790799 (1974-02-01), Stein et al.
patent: 4618772 (1986-10-01), Haas et al.
patent: 5642393 (1997-06-01), Krug et al.
patent: 0311177 (1989-12-01), None
Dau Hans-Detlef
Geistmann Bernd
Martens Gerhard
Peemoller Horst
Church Craig E.
Kueffner Friedrich
YXLON International X-Ray GmbH
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