AU2005201989A1 - X-ray inspection apparatus for foreign matter - Google Patents

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority Related Art: Name of Applicant: Takashima Giken Co., Ltd.

Actual Inventor(s): Yoshihiko Takashima Address for Service and Correspondence: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street Melbourne 3000 AUSTRALIA Invention Title: AN 0 X-RAY INSPECTION APPARATUS FOR FOREIGN MATTER Our Ref: 744429 POF Code: 1592/472450 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): -1-

'I]

in X-RAY INSPECTION APPARATUS FOR FOREIGN MATTER BACKGROUND ART The present invention relates to an X-ray inspection apparatus for foreign matter.

For example, when an object to be inspected is a cylindrical glass bottle with a circular cross-section, X-rays are irradiated from above to the 0 object so as to detect any foreign matter such as glass chips mixed in a content of the bottle. In this case, no blind or dead zones exist in the glass I 10 bottle so that mere irradiation of X-rays from above results in sufficiently accurate inspection of the glass bottle.

However, in recent years, there has been increased tendency toward glass bottles each with a multi-curved complex contour so as to have eyecatching design. An example is shown in Figs. 1-3 in which reference numeral 1 denotes a glass bottle body with an irregularly complex contour comprising a potbellied curved surface la and a slightly curved surface lb with a curvature larger than that of the surface la; 2, a cap; 3, a powdery content such as powdered coffee or milk powder; and 4 and 5, foreign matter such as glass chips mixed in the powdery content 3 of the bottle body 1.

When inspection is to be made to check whether or not foreign matter 4 and 5 is mixed in the powdery content 3 of such irregular-shaped glass bottles, irradiation of X-rays in a single direction do not lead to a precise and accurate inspection.

More specifically, as shown in Fig. 4, X-rays diffusively irradiated from an X-ray source 6 to the glass bottle body 1 with an irradiation range e of about 350 for detection of foreign matter pass through the curved surface I b of the bottle body 1, the powdery content 3 and the curved surface l a of the bottle body 1 through each of routes a-e and are detected by the X-ray detector 7. In this case, the X-rays pass through the curved surfaces I b and la substantially perpendicular thereto at a center of the irradiation range e while they pass through them slantingly thereto at sides of the irradiation range e. As a result, the X-rays through the route c have little loss amount since a sum of distances L1 and L2 of penetrated or transmitted glass portions is small while the X-rays through the route e at a corner of the body 1 have much loss amount since a sum of distances L3 and L4 of penetrated

O

Oor transmitted glass portions is large.

Accordingly, X-ray transmission intensity in the irradiation range e (see Fig. 4) has a mound-like distribution curve as shown in Fig. 5 where it is S 5 high at the center represented by the route c and is low at the sides represented by the routes a and e. As a result, the foreign matter 4 inside the curved surface l a and in the route c can be detected whereas the foreign 00 00 matter 5 at the corner between the curved surfaces l a and lb and in the outside route a or e within the irradiation range e (shown in the route e in Fig.

i- 10 4) is difficult to detect unless the foreign matter is a metal with extremely 0 high density since it is at the corner as the dead or blind zone. In the case of the foreign matter 5 being a glass chip, its detection is impossible.

Thus, whether foreign matter can be detected or not depends on product of loss amount of X-ray per unit length of glass and thickness of the glass bottle body 1 and on ratio between a density of the powdery content 3 and that of the foreign matter 4 or 5. If such densities are much different, the detection may be successful; if not, the detection will fail.

If the glass bottle is rotated while the inspection is conducted, then irradiation of X-rays even in a single direction may lead to a precise and accurate inspection of checking whether or not there is foreign matter mixed in the powdery content of the glass bottle with the above-mentioned irregular contour. However, this makes the inspection time-consuming and thus inefficient. For example, in a production line for food, say about 600 glass bottles per minute have to be charged with a powdery content during conveyance of the glass bottles by a conveyer apparatus; the execution of the inspection in post-processing after charging of the glass bottles with the powdery content and during conveyance and rotation of the glass bottles would require speeding up of the inspection, which is unrealistic. On the other hand, if the inspection is lowered in speed for accuracy thereof, production of the products cannot be efficiently conducted.

An inspection apparatus with X-rays irradiated in two directions has been proposed in order to detect foreign matter mixed in a powdery content in a glass bottle. Such X-ray inspection apparatus is disclosed in, for example, Japanese Utility Model No. 3079206. In order to detect foreign 'n matters such as glass chips in a glass bottle, the inspection apparatus disclosed in the Japanese Utility Model comprises two series of detection systems. In one of the detection systems, X-rays are irradiated laterally to the glass bottle so as to take side images of the bottle by means of a ray sensor with a scintillator; in the other detection system, X-rays are irradiated from above to the glass bottle so as to take bottom images of the bottle by o means of a further ray sensor with a scintillator through a conveyance 00 o surface of the conveyor. The X-rays are thus two dimensionally used to check whether or not there is foreign matter.

Ij 10 However, in the inspection apparatus according to the Japanese Utility Model, there is a possibility that dead or blind zones may be caused depending upon the position of the glass chips in the glass bottle, failing in detection of the foreign matter. More specifically, just like the case where an inspection is conducted by irradiating X-rays in a single direction, foreign matter may be detected at positions where the X-rays pass through the curved surface of the glass bottle substantially perpendicular thereto since the X-rays have little loss amount whereas foreign matter may be hardly detected at positions such as corners of the bottle where the X-rays pass through the curved surface of the glass bottle slantingly since X-rays have a high loss amount, the corner of the bottle being a dead or blind zone.

It should be noted that the discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of any of the claims.

The present invention was made in view of the above and has its object to provide a new X-ray inspection apparatus for facilitating foreign matter detection.

BRIEF SUMMARY OF THE INVENTION Viewed from one aspect, the present invention provides an X-ray inspection apparatus for foreign matter including: three X-ray sources for irradiating a predetermined vessel with X-rays in three-dimensional directions; three X-ray detectors for detecting X-rays irradiated by the corresponding X-ray sources; and an image processing unit for processing

O

0 images detected by the X-ray detectors to check whether or not there is foreign matter in the vessel.

The present invention may detect foreign matter in a vessel accurately 0 5 and reliably without lowering production efficiency of bottled products. The invention is based on a viewpoint that an X-ray inspection in three different directions or three-dimensional directions is most suitable for inspection of a 00 three-dimensional object, which fact was found out by researches of the Sinventor.

10 The image processing unit may include a signal detecting section for 0 detecting and outputting output images on the basis of images from the X-ray detectors, an arithmetic section for carrying out predetermined calculations on the basis of the output images from said signal detecting section to output resultant output images as light/shade images, a processing section for processing the output images from said arithmetic section to output resultant output images as differential images, and a foreign matter detecting section for detecting foreign matter on the basis of the output images from said processing section.

The arithmetic section in the image processing unit may be adapted to calculate, on the basis of the output images from the signal detecting section and set to a plurality of light/dark portion inspection ranges, data differences in each of the set inspection ranges, thereby obtaining resultant output images.

In the foreign matter detecting section of the image processing unit, voltage of a pixel may be compared with that of a next pixel to obtain light/shade portions. Judgment may be made that foreign matter exists when area and/or voltage of such light/shade portions is lower than a preset threshold as a reference, and judgment may be made that no foreign matter exists when higher than the preset threshold.

The X-ray inspection apparatus for foreign matter according to the present invention may be adapted to conduct an inspection of a vessel being conveyed by a conveyor apparatus, so as to determine the presence of foreign matter or not.

In the X-ray inspection apparatus for foreign matter according to the o present invention, X-rays are irradiated in three-dimensional directions to a

O

0 vessel that may be conveyed by a conveyor apparatus, the irradiated X-rays

(N

being detected by the X-ray detectors into the image processing unit where detection is made of whether there is foreign matter in the vessel or not.

In the signal detecting section of the image processing unit, output images are detected and outputted on the basis of images from the X-ray detectors; in the arithmetic section, calculations are made on the basis of the 0 output images from the signal detecting section to output resultant output images as light/shade images; in the processing section, the output images from the arithmetic section are processed to obtain and output resultant Soutput images as differential images; and in the foreign matter detecting section, whether there is foreign matter or not is detected on the basis of the output images from the processing section.

Viewed from another aspect, the present invention provides conveyor X-ray inspection apparatus for inspecting the contents of vessels moving along a conveyor line for foreign matter in the contents, the apparatus including: three X-ray source means, each of which is arranged to irradiate vessels moving along the conveyor line from a different irradiation direction to that of the other X-ray source means; three X-ray detector means for detecting X-rays emitted by the three X-ray source means; and image processing means for processing the output of the three X-ray detector means to determine whether or not foreign matter is present in the contents of the irradiated vessels.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front view showing an example of a glass bottle which tends to have dead or blind areas when X-rays are irradiated in one- or twodimensional directions; Fig. 2 is a view looking in the direction of arrows II in Fig. 1; Fig. 3 is a view looking in the direction of arrows III in Fig. 2; Fig. 4 is a model diagram used for explanation of a reason why foreign matter such as glass chips are hardly detected at a corner of a glass bottle when the foreign matter is mixed in a content charged in the glass bottle with a complex and irregular curved contour; Fig. 5 is a graph showing relationship between X-ray transmission Sintensity and X-ray route with respect to X-rays passing through the glass bottle shown in Fig. 4; Fig. 6 is a perspective view showing an embodiment of an X-ray inspection apparatus for any foreign matter according to the invention; Fig. 7 is a front view of the X-ray sources and the X-ray detectors o shown in Fig. 6 and looking in the direction parallel to the direction of 00 0 conveyance of a belt conveyor; Fig. 8 is a block diagram showing an example of an image processing I 10 unit applied to the X-ray inspection apparatus for any foreign matter according to the invention; Fig. 9 is a model diagram showing an example of output images obtained by a signal detecting section in the image processing unit; Fig. 10 is a model diagram showing an example of output images obtained by an arithmetic section in the image processing unit; Fig. 11 is a model diagram showing an example of output images obtained by a processing section in the image processing unit; and Fig. 12 is a model diagram showing an example of output images obtained by a foreign matter detecting section in the image processing unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the invention will be described in conjunction with drawings.

Figs. 6-12 show an embodiment of the invention. In Figs. 6 and 7, reference numeral 11 denotes a belt conveyor with a belt through which Xrays may pass. A glass bottle 12 which has been charged with a powdery content in pre-processing is conveyed by the conveyor 11 in a direction of arrow D. Reference numerals 4 and 5 designate foreign matter such as glass chips mixed in the powdery content charged in the glass bottle 12. The shape of the glass bottle 12 is substantially similar to that shown in Figs. 1-3.

In Fig. 7, three pairs of X-ray sources 13a, 13b and 13c and X-ray detectors 14a, 14b and 14c are arranged at predetermined positions of a carrier line for the belt conveyor 11 so as to conduct detection in threedimensional directions (three different directions). More specifically, the X-

I

ray source 13a is arranged at an inspection location and just above the glass bottle 12. The X-ray detector 14a is horizontally arranged underneath a conveyance surface of the belt conveyor 11 and just below the glass bottle 12 in such a manner that a receiving surface of the detector 14a extends laterally of the belt conveyor 11.

The X-ray source 13b is arranged, for example, at one of the lateral sides of the belt conveyor 11 in such a manner that the source 13b has an 0axis 15b tilted by a predetermined angle to a vertical axis 15a of the X-ray source 13a. In order to detect the X-rays irradiated by the X-ray source 13b,

(N

the X-ray detector 14b is arranged below the conveyance surface of the belt 0conveyor 11 and slantingly extends upwardly of the other lateral side of the conveyor 11 in such a manner that a receiving surface of the detector 14b is orthogonal to the axis 15b of the source 13b.

Further, the X-ray source 13c is arranged, for example, at the other of the lateral sides of the belt conveyor 11 (at the side opposite to the X-ray source 13b with respect to the X-ray source 13a) in such a manner that the source 13c has an axis 15c tilted by the predetermined angle to the vertical axis 15a of the X-ray source 13a, the axis 15c of the source 13c being opposite to the axis 15b of the source 13b with respect to the axis 15a of the source 13a. In order to detect the X-rays irradiated by the X-ray source 13c, the X-ray detector 14c is arranged below the conveyance surface of the belt conveyor 11 and slantingly extends upward of the one lateral side of the conveyor 11 in such a manner that a receiving surface of the detector 14c is orthogonal to the axis 15c of the source 13c. Each of the X-ray detectors 14a, 14b and 14c is, for example, a ray sensor with a scintillator and comprises a number of elements juxtaposed in a line and the glass bottle 12 is conveyed by the belt conveyor 11 even during the inspection, so that twodimensional image signals can be detected.

Image signals of the X-rays detected by the respective X-ray detectors 14a, 14b and 14c can be given to an image processing unit 16. Fig. 8 shows an internal constitution of the image processing unit 16. In Fig. 8, as a matter of convenience, the internal constitution of the image processing unit 16 is shown with respect to a system of the X-ray source 13b and the X-ray detector 14b. It is to be noted that systems of the X-ray sources 13a and 13c and the X-ray detectors 14a and 14c, respectively, have internal constitutions Ssimilar to that of the system of the X-ray source 13b and the X-ray detector 14b.

In Fig. 8, reference numeral 17 denotes a signal detecting section for detecting and outputting output images on the basis of images from the X-ray detector 14b; 18, an arithmetic section for carrying out predetermined o calculations on the basis of the output images from the signal detecting 00 section 17 and for outputting resultant output images as light/shade images; 019, a processing section for processing the output images from the arithmetic I 10 section 18 and outputting resultant output images as differential images; and a foreign matter detecting section for detecting any foreign matter on the basis of the output images from the processing section 19. When judgment is made by the foreign matter detecting section 20 that any foreign matter is mixed in the powdery content of the glass bottle 12, the detecting section sends to a drive of an eliminator (not shown) a command for driving the eliminator to remove the glass bottle 12 with the foreign matter out of the belt conveyor 11.

Reference numeral 21 denotes a drive circuit which sends, at startup of an inspection, an activation command to the X-ray detector 14b and at the same time sends to the signal detecting section 17 a command for startup of the detection of the output images from the X-ray detector 14b.

Next, a mode of operation of the above embodiment will be described.

The X-rays irradiated from the X-ray sources 13a, 13b and 13c to the glass bottle 12 being conveyed by the belt conveyor 11 are detected by the X-ray detectors 14a, 14b and 14c and their outputs are passed to the image processing unit 16 where predetermined processings are carried out to judge whether there is foreign matter 4 and 5 or not. In the following description, the process of detecting foreign matter will be explained only with respect to the X-ray detector 14b; however, the same will apply to the X-ray detectors 14a and 14c.

The glass bottle 12 having been charged with the powdery content in an upstream process is conveyed by the belt conveyor 11 to the inspection location. Then, the drive circuit 21 sends to the X-ray detector 14b the command for startup of the detection of the X-rays irradiated by the X-ray source 13b and at the same time sends to the signal detecting section 17 the 0 command for startup of the detection of the images from the signal detecting

(N

section 17.

The X-rays irradiated by the X-ray source 13a and passing through the glass bottle 12 are detected as images by the X-ray detector 14b and the output is sent to the signal detecting section 17 where obtained on the basis of the detected images are output images (see Fig. 9) which are outputted to o00 the arithmetic section 18. The output images from the signal detecting section 17 are light/shade signals in terms of weaker and stronger intensities 10 of the X-rays, the foreign matter being outputted darkly against a background of mean lightness. In Fig. 9 which shows the images detected by the signal detecting section 17, reference numeral 12a denotes an image representative of the glass bottle 12; 22a, a shade image; 22b, an extreme shade image; 22c, a light image; 4a and 5a, images of foreign matter; and 24a, an image of a glass portion through which X-rays pass over an extremely long distance.

In the arithmetic section 18, for the output images from the signal detecting section 17, a plurality of kinds of light/dark portion inspection windows (inspection ranges) are automatically set to determine data differences in the respective ranges, thereby obtaining processed images (see Fig. 10). That is, the output images from the signal detecting section 17 are divided into light/dark portions and calculations are made on the basis of these signals to obtain the processed images.

In the arithmetic section 18, the light/shade images are converted into addressed signal voltage changes (shade and light are low and high in voltage change, respectively). Thus, calculations of voltages are carried out using four fundamental rules of arithmetic. In order to easily find out difference in voltage of foreign matter to the surrounding portions, logarithmic conversion, three-pixel averaging or the like is used; and output images are outputted through a highpass filter as light/shade images. In Fig. 10 which shows the images detected in calculation by the arithmetic section 18, reference numeral 12b designates an image representative of the glass bottle 12; 23a, a dark portion window for light/shade images; 23b, an extreme dark portion window for light/shade images; 23c, a light portion 11 window for light/shade images; 4b and 5b, images of foreign matter; and

O

0 24b, an image of a glass portion through which X-rays pass over an extremely long distance.

The processed images obtained through calculations by the arithmetic O 5 section 18 are outputted into the processing section 19 where differences between pixels are obtained into output images (see Fig. 11). In Fig. 11 which shows the images obtained in processing by the processing section 00 19, reference numerals 4c and 5c are images of for example foreign matter O which are output images; and 24c, an image of a glass portion through which t' 10 X-rays pass over an extremely long distance.

O

O With respect to output images outputted from the processing section

(N

19 into the foreign matter detecting section 20, voltage of one pixel is compared with that of a next pixel to obtain light/shade. If its area and/or voltage is lower than a preset threshold as reference, judgment is made that foreign matter exists; if higher than the threshold, judgment is made that no foreign matter exists (see Fig. 12). In Fig. 12, images 4c and 5c of Fig. 11 are left and are judged to be foreign matter while the image 24c disappears and is judged not to be a foreign matter. Also in the systems of X-ray detectors 14a and 14c, detection is made as to the existence/non-existence of foreign matter just like the case of the X-ray detector 14b.

When judgment is made by the foreign matter detecting section that foreign matter exists, a command is sent to the drive of the eliminator for driving the eliminator to remove the glass bottle 12 with the foreign matter out of the belt conveyor 11.

According to the embodiment, whether or not foreign matter 4 and such as glass chips are mixed in powdery content of the glass bottle 12 is checked or inspected by irradiation of X-rays in three-dimensional directions, so that foreign matter 4 and 5 can be detected accurately and reliably with no dead or blind zone at an inner curved portion or at a corner of the glass bottle 12, thereby enhancing reliability of the inspection. The production efficiency of bottled products is not lowered since there is no need to rotate the glass bottle 12 during the inspection.

It is to be understood that the invention is not limited to the above embodiment and that various changes and modifications may be made without departing from the scope and spirit of the invention. For example, 0the description has been made on the application to a glass bottle, but the

(N

.invention may be applied to any vessels other than a glass bottle such as plastic bottles, steel cans or aluminum cans. Application may be made not 0 5 only to bottles but also to cup-like vessels. Though the description has been made on a glass bottle with powdery content, the content may not be limited to powder. The powdery content is not limited to powdered coffee or milk 00 powder. Application may be also made on vessels with content other than 0 food. Application may be made on vessels of any shape.

tr 10 An X-ray inspection apparatus for any foreign matter according to the 0 invention has various excellent features and advantages. For example, whether or not foreign matter such as glass chips are mixed in powdery content of the glass bottle is checked or inspected by irradiation of X-rays in three-dimensional directions, so that foreign matter can be detected accurately and reliably with no dead or blind zones at inner curved portions or at corners of the glass bottle, thereby enhancing reliability of the inspection, whilst production efficiency of the bottled products is not lowered since there is no need to rotate the glass bottle during the inspection.

Claims (8)

1. An X-ray inspection apparatus for foreign matter including three X-ray sources for irradiating a predetermined vessel with X-rays in three- dimensional directions, three X-ray detectors for detecting X-rays irradiated by the corresponding X-ray sources, and an image processing unit for processing images detected by the X-ray detectors to check whether or not oo 0 there is foreign matter in the vessel.

2. The apparatus according to claim 1, wherein said image processing unit 0 includes a signal detecting section for detecting and outputting output images on the basis of images from the X-ray detectors, an arithmetic section for carrying out predetermined calculations on the basis of the output images from said signal detecting section to output resultant output images as light/shade images, a processing section for processing the output images from said arithmetic section to output resultant output images as differential images, and a foreign matter detecting section for detecting foreign matter on the basis of the output images from said processing section.

3. The apparatus according to claim 2, wherein said arithmetic section is adapted to calculate, on the basis of the output images from the signal detecting section and a plurality of light/dark portion inspection ranges, data differences in each of the inspection ranges, thereby obtaining resultant output images.

4. The apparatus according to claim 2 or 3, wherein voltage of a pixel is compared with that of a next pixel to obtain light/shape portions, judgment being made that foreign matter exists when area and/or voltage of such light/shade portions is lower than a preset threshold as a reference, judgment being made that no foreign matter exists when area and/or voltage of such light/shade portions is higher than the preset threshold.

The apparatus according to any one of claims 1 to 4, which is adapted to conduct an inspection of a vessel being conveyed by a conveyor apparatus, so as to determine the presence of foreign matter or not.

6. Conveyor X-ray inspection apparatus for inspecting the contents of vessels moving along a conveyor line for foreign matter in the contents, the 0 5 apparatus including: three X-ray source means, each of which is arranged to irradiate vessels moving along the conveyor line from a different irradiation direction to that of the other X-ray source means; three X-ray detector means o00 for detecting X-rays emitted by the three X-ray source means; and image processing means for processing the output of the three X-ray detector means to determine whether or not foreign matter is present in the contents of the irradiated vessels.

7. The apparatus of claim 6, including a first X-ray source means for irradiating the vessel in a direction perpendicular to the conveyor line, a second X-ray source means for irradiating the vessel from one side of the conveyor line, and a third X-ray source means for irradiating the vessel from the other side of the conveyor line, the irradiation axis of the second X-ray source means and the irradiation axis of the third X-ray source means being at an acute angle to the irradiation axis of the first X-ray source means.

8. X-ray apparatus substantially as hereinbefore described with reference to Figs. 6 to 12. DATED- 10 May 2005 PHILLIPS ORMONDE &PFITZPATRICK Attorneys for: TAKASHIMA GIKEN CO., LTD. 49 cz