DE19823448A1 - Object examination device using X-rays, for inspection of luggage or containers - Google Patents

Abstract

The device uses X-rays provided by a point source (6), directed through the examined object (1) onto a detector (12,13) providing an image signal which can be viewed on a monitor after entry in a temporary memory. The examined object is moved relative to the beam direction for provision of a stereoscopic image using two incidence directions offset by an angle corresponding to the angle between the line of sight for each eye of the observer. The detector array comprises two spaced linear receivers, which are displaced off-center displaced in the movement direction and are arranged perpendicular to the plane of the sensor image.

Description

The invention relates to a device for checking Ge objects, especially luggage or containers, by means of X-rays according to the preamble of the An saying 1.

Such a device for inspecting objects by means of X-rays, which - starting from a single against essentially point-shaped X-ray source the item to be checked through at a receptionist order generates the signal of a silhouette which after buffering in a memory on a moni gate is made visible, the X-ray pulse generator and the buffer for image acquisition and playback are suitably synchronized, is from the US patent No. 5 155 750. In the known device, wel preferably for the inspection of smaller parts the imaging system for online Representation from a screen, which the object into recorded in total. The stereoscopic reproduction takes place there through that two at different times by densel ben image sensor captured images after buffering the eyes of the beholder separately.

The disadvantage is that the entire object is the same must be recorded early. The necessary pictures Participants are disproportionate to larger items complex and prevent economic use ner such device. The image sensor must do this not just be able to position the item in one position to capture, but must also include its inclusion in un allow different positions, so that the Querab  measurements of those of the object plus feed must correspond.

The invention is therefore based on the object at egg ner device of the aforementioned type the possibility manage to examine larger objects without Image recorders are required, which allow the entire object in its original size at the same time desired resolution.

This task is based on a device according to the preamble of claim 1, characterized in nenden part of claim 1 specified features solved.

The invention includes the technical knowledge that it for the stereoscopic display of X-ray images diglich is necessary to ver the picture by two to each other set line-shaped line sensors at the height of the Ob project during a run. Here you can the signals from the two line sensors during the pre thrusts are fed to different memories, wel che then separately for later presentation agreed to take pictures.

The radiation of the object relative to the x-ray Source occurs during the "scanning scan" of the un searching objects simultaneously or one after the other different spatial directions, which around such Angles are offset from each other, which is essentially or at least the angular offset of the viewing directions Fixation of the object when seeing spatially from the location of the X-ray pulse generator corresponds so that looking at the picture gives a spatial impression.  

This is particularly noteworthy because the simultaneous exposure of a full frame the beam direction are different. This also applies to norma le spatial vision. So here actually one "Adulteration" compared to the normal physiological Spatial impression, it has been shown that despite the Simplicity of the equipment even with larger objects produced an excellent stereoscopic impression becomes.

The device according to the invention is particularly suitable for screening luggage and containers, such as they are used in aviation and shipping. A Such screening is increasing for security reasons mend required.

Interestingly, there is stereoscopic vision impression if that was captured by the right line sensor Image is fed to the left eye and vice versa. Bemer It is worth noting that the entire generation of the stereoscopic impression of the viewer's human brain is taken over, so that no processor power is required. This also helps to reduce the Manufacturing cost of the device.

With an x-ray generator and two detectors, they are multan recorded a left and a right picture, the after saving and corresponding preparation the lin The right eye and the right eye of man are offered separately the.

Using a classic x-ray tube can do this a generator can be provided, the x-ray pulses  sends, which selects a measurement based on its pulse duration enable the impulse. Due to the performance con Traction in the impulse occurs during the impulse significantly higher signal level available than with Dau screed generators can be expected. The clearly excessive te signal level then allows a higher detection dynamic in X-ray inspection devices. Despite the high Si dose level remains during the measurement of the object is comparable or is smaller than for duration line process. The dead time between the pulses allowed a quasi - simultaneous measurement of the background, which Correction purposes can be used.

In an advantageous variant of the invention, it is provided hen that the longitudinal dimension of the line pickup each at least equal to the corresponding dimension of the un is searching object, so that a scanning Abta can take place over the total extent. Here are the line sensors arranged in a row Provided sensors, each one essentially punctiform recording surface with a small viewing angle assign and in their number of the intended dissolution are adapted to the image. Through line-by-line scanning is the number of transducers required even with high Resolution relatively low. The spatial orientation of the Sensors are each provided so that their maximum spatial sensitivity to the location of the x-ray source sums up. The sensors are therefore individual within the line always aimed at the x-ray source.

The pulse frequency of the X-ray source is on the Relativge speed and the number of sensors per length in the It is agreed that the resolution of the im  Pulse generated pixels per length essentially the resulting from the number of sensors per unit length Resolution corresponds. So the number of pulses per second related to the feed rate. So with egg a feed rate of 100 mm / s a resolution of 1 point / per mm, the pulse frequency must be 100 Hz amount, with the exposure for both line sensors is done simultaneously. To increase the lifespan of the x-ray source a thermal source is preferably provided.

If it is desired to create a representation of what exactly corresponds to the physiological conditions, can the relative movement between object and recording can also be arranged on a curved path, the Center of curvature on the distance from the X-ray source turned side on a middle vertical between the Li is located.

Is the stereoscopic view in a spatial direction not sufficient, an additional "trip" of the Object in buttocks rotated by 90 ° around a vertical axis sition to be undertaken. This would be on the sled a turntable ahead of a transport device hen. The feed can also take place in the vertical direction gene, for which the line sensors advantageously around 90 ° a horizontal axis can be pivoted. The contemplation for the viewer, the object is then "with head tilted to the side " our assignment option as a pivoting of the counter stands, because in this case a change of inventory of parts ment can take place, especially if it concerns Be holder for objects. The ver different runs are preferably carried out in un  different - preferably perpendicular to each other existing spatial directions.

An elek is also used to clarify the image tronic image post-processing cheap. This will depend on A false color representation is provided, which illustrates the edge effects. A non-linear Signal processing makes it possible - even with black white rendering - highlight contrasts.

To the stored images ge the eyes of the observer Monitors for stereoscopic loading must be fed separately suitable, which also in CAD applications Ver find application. It is convenient to use a monitor at twice the frame rate, at which alternately represents the image intended for the left and right eyes position and between two pictures with a suitable pre-filter the polarization direction reversed is switched. The stereoscopic image can then be used look at glasses that are ent for each eye speaking differently aligned polarization film ter.

Other advantageous developments of the invention are in the subclaims or are identified below along with the description of the preferred embodiment the invention with reference to the figures. It demonstrate:

Fig. 1 as a preferred embodiment of the dung OF INVENTION a device for screening of Flugcontai partners with the corresponding beam guidance in Seitenan view,

Fig. 2 shows the embodiment of Fig. 1 in top view,

Fig. 3 is a block diagram as a detail for the execution of FIG. 1 and

Fig. 4 shows a variant of the embodiment in a schematic representation.

In the side view shown in Fig. 1, it is evident how a container 1 is to be X-rayed object on a carriage 2 in the radiation cone of an X-ray source is moved perpendicular to the image plane. The carriage 2 is moved on a frame 3 with rollers 4 on rails 5 perpendicular to the image plane - that is, in the horizontal direction. The x-ray source 6 is located in a housing 7 on a base frame 8 , which lifts the x-ray source to the level of the object. An aperture 9 on a carrier 10 hides the relevant part of the radiation. (For the sake of clarity, the rest of the shielding connected to the aperture 9 has been omitted in the illustration. However, it is clear to the person skilled in the art with X-ray technology that the arrangement requires a suitable shielding with corresponding locks. The known ones provide indications for this Devices for screening luggage at airports.

The radiation cone 11 is directed by the object to be traversed by the area to be traversed to linear sensors 12 and 13 , each of which testifies a time-shifted scan signal from different angular directions. The central axis of the beam cone is designated in Fig. 1 with 14 and the central axis of the object with 14 a net. The individual sensors on the linear recorders form an array of individual sensors with an almost punctiform sensitivity range, each of which is individually oriented towards the radiation source. They are therefore attached to a holder with different inclinations (in side view), although they all point in the same direction in plan view (per transducer).

The geometric arrangement is additionally shown in the top view in FIG. 2. It can be seen that the linear sensors 12 and 13 , which each have an array of punctiform sensors, produce two images with horizontal lines. The meaning of the reference numerals basically corresponds to that in FIG. 1. In addition, the axis of symmetry 14 and the horizontal boundaries 15 and 16 of the beam cone 11 are shown. An object 1 passes the beam cone 11 in the drawing in the direction from top to bottom (direction of arrow P).

It can be seen that the two output signals of the line sensors 12 and 13 which form stereoscopic images are taken simultaneously - but spatially offset - on. They are expediently "put together" in the memory when addressing so that the same object parts are stored in the same way, so that when reading a common addressing of the two different images containing the memory parts can be done. In other words, the images taken from the two different viewing directions are not taken from two different directions as in spatial viewing, but are fed from the one point source 6 to the two linear sensors 12 and 13 in different directions. As a result, the two ste reoscopic images are also slightly offset in time. However, this is irrelevant, since the object 1 itself is usually not movable, since non-living objects are transported in containers. If, contrary to expectations, there is a living object in a container, the movement between the two scans leads to a clear falsification of the stereoscopic image, which alone is a clear indication and attracts the appropriate attention of the operator.

The schematic block diagram shown in FIG. 3 shows this signal processing in detail on the basis of the modules involved. In addition to the modules already described, which have the same reference numerals, the following system elements are provided: The lines 12 and 13 are excluded from a feed control unit 16 from the line-shaped sensors addressed memories 17 and 18 , in which the lines of the line-shaped sensors 12 and 13 - via digitalization units, not shown - for the storage in the digital memory in a digital code processed signals are recorded line by line. A delay element 19 in the form of a shift register ensures the synchronization of the signals for the later common reading out by means of parallel addressing. This is coordinated with the feed rate in such a way that the delay time corresponds precisely to the time that the object 1 on the travel path 15 needs to overcome the projection of the distance between the two linear sensors 12 and 13 in the direction of movement. According to the ray set, the path of an object point on the movement straight line 14 a from line 15 to line 16 of the beam cone is to be taken into account here as the feed path of object 1 . The intersection points are decisive here. The two lines 15 and 16 represent the straight-line connections from the radiation source 6 to the line-shaped sensors 12 and 13 .

In the illustration according to FIG. 3, this means that the image which is recorded by the first line sensor is delayed compared to the second or is stored in the memory for the image with a corresponding offset. The delay is therefore chosen so that it corresponds to the duration that the same image parts require, from the detection from the first to the second line sensor. In this way, two images are generated which - although they were taken with a time delay - correspond in their geometry to images as they are taken by a person's two eyes in natural light. It should be noted that the image from the left sensor is fed to the right eye and vice versa. For this purpose, a control unit 20 is used , which alternately feeds a monitor intended for the left and right eyes to a monitor with a high image change frequency, which image is polarized alternately horizontally and vertically by a polarization filter 22 . The viewer wears glasses 23 which have a corresponding polarization filter for each eye.

Fig. 4 shows schematically that the container on a turntable can also be rotated by 90 ° who can to gain a different viewing direction in three-dimensional representation as a supplement to the information. For a shift in the vertical direction of the object 1 with a kind of elevator 24 , the lines sensors are rotated from the vertical position shown in solid lines to the positions 12 'and 13 ' shown in dashed lines by 90 ° in the horizontal direction, so as to also produce a stereoscopic image win, which then shows the container lying on its side and can be viewed accordingly. The pivoting process of the Liniensenso ren 12 and 13 in the position 12 'and 13 ' is indicated by the arrow 26 .

In order to additionally gain a further stereoscopic viewing direction into the object, the object is arranged rotatably about a vertical axis on the transport carriage 2 . The use of this option depends on the geometric conditions and is preferably considered if the object corresponds approximately in its horizontal dimensions to a quadratic or circular contour, so that the transmission cross sections are essentially the same. It is often advisable to look at it from different directions if the object offers preferred directions of radiation in which only short distances can be penetrated.

The invention is not restricted in its implementation to the preferred embodiments given above games. Rather, a number of variants are possible which of the solution shown also in principle makes use of different types. So around also swept the measuring arrangement towards the object be moved if it is immovable or very large is.

Claims (22)

1. Apparatus for checking objects, in particular re luggage or containers, by means of X-ray radiation, which - starting from an essentially point-shaped source - generates the signal of a shadow image through the object to be tested in a receiving arrangement, which after temporary storage in a Memory is made visible on a monitor, the X-ray pulse generator and the buffer being appropriately synchronized for image recording and playback,
wherein for stereoscopic image display the object is moved transversely to the direction of irradiation and various signals corresponding to the shadow images are supplied separately as image displays to the eyes of the viewer after buffering, characterized in that
that the radiation of the object relative to the X-ray source in different fixed spatial directions it follows, which are offset from one another by an angle which essentially corresponds to the angular displacement of the viewing directions of the eyes when the object is fixed in spatial vision,
and that the sensor arrangement consists of two line-shaped sensors laterally offset by a distance in the direction of movement, perpendicular to the direction of movement in the plane of the sensor image. 2. Device according to one of the preceding claims, characterized in that the angle insert over the way of the object is constant. 3. Device according to one of the preceding claims, characterized in that the longitudinal dimension of the lines shaped transducer at least equal to the corresponding accordingly dimension of the counter to be examined is. 4. Device according to one of the preceding claims, characterized in that the line from the left Sensor captured image is fed to the right eye and vice versa. 5. Device according to one of the preceding claims, characterized in that the linear transducers with a number on a straight connecting line arranged sensors for X-rays provided are, 6. Device according to one of the preceding claims, characterized in that the linear transducers a number of sensors arranged in a row point, which each have a substantially punctiform Have a surface with a small viewing angle. 7. Device according to one of the preceding claims, characterized in that the spatial orientation of the  Sensors are each provided so that their maximum spatial sensitivity to the location of the x-ray source sums up. 8. Device according to one of the preceding claims, characterized in that it is the X-ray source is a pulsed X-ray source, the pulse fre quenz on the relative speed and the number of Sensors are matched per length in such a way that the Resolution of the pixels generated by the impulse per length essentially the number of sensors corresponding resolution per unit length. 9. Device according to one of the preceding claims, characterized in that a thermal emission tube is provided as an X-ray source. 10. Device according to one of the preceding claims, characterized in that the X-ray source and the Sen sor on the one hand relative to the object on the other hand on egg a straight path or a curved path is moved, in the case of a curved path the curvature means seen from the x-ray source, behind the opening participants, especially on a medium perpendicular to it is laying. 11. Device according to one of the preceding claims, characterized in that means are provided to the Object in different - preferably vertical  superimposed spatial directions - through the beam area. 12. Device according to one of the preceding claims, characterized in that a carriage for moving the Ge object between radiation source and transducers is seen, in particular provided with a turntable is. 13. Device according to one of the preceding claims, characterized in that the object relative to Radiation source and the transducers in a vertical Direction is movable, in particular means provided hen are common to the line pickup by 90 ° vertical to swivel sam into a horizontal position. 14. Device according to one of the preceding claims, characterized in that synchronization means for intermittent storage of the output signals of the sensors of the linear transducers in coordination with the relative movement of object and radiation source or recording are provided. 15. Device according to one of the preceding claims, characterized in that drive means for the counter was due from a - especially by a stepper motor driven carriage and / or a displacement sensor.   16. Device according to one of the preceding claims, characterized in that means are provided which the storage of the two linear recordings n recorded images are recorded in such a way that identical picture elements of the object coincide corresponding storage locations can be assigned. 17. The apparatus according to claim 16, characterized net that the storage in a first memory area with a time delay in relation to a second memory area t or offset. 18. The apparatus according to claim 17, characterized in net that delay corresponds to the time which an el ment of the object needed to be from a radiation area the X-ray source, which is the first in the feed direction line-shaped pickup reached to a radiation beam range of the x-ray source to get to the one in front direction of thrust reaches second linear transducer. 19. Device according to one of the preceding claims, characterized in that means for electronic Post-processing is provided. 20. Device according to one of the preceding claims, characterized in that the means for electronic Post-processing means for displaying false colors in Dependence on the amplitude level of the recorded signal exhibit.   21. Device according to one of the preceding claims, characterized in that non-linear distortion means to increase contrast, especially in the range of Contours are provided. 22. Device according to one of the preceding claims, characterized in that a downstream monitor provided with switching means for a polarization filter which is alternating from one line to the next signal received by one of the polarization directions gen assigned.