METHOD AND APPARATUS FOR IN-LINE INSPECTING OF PACKAGING

Abstract: The present invention relates to a method for inspecting packagings for liquid medium, such as glass bottles optionally filled with beer or other drink, wherein the packagings are moved in line at predetermined speed and/or predetermined mutual spacing, and wherein images of the packagings are recorded by a number of cameras disposed adjacently of or successive to each other, and these images from the different cameras are combined in order to detect foreign substances therein.

Description: METHOD AND APPARATUS FOR IN-LINE INSPECTING OF PACKAGING Following an incident in 1993, in which glass splinters were found to be present in beer, a well-known Dutch beer manufacturer started a project to enable detection of glass splinters -in filled glass beer bottles. A proposed solution is described in the international patent application PCT/NL96/00049. A head with drive motor for rotating a beer bottle is herein placed on a carrousel and, using a CCD camera, a number of images are recorded by the CCD camera after the rotation movement has been interrupted, and these images are analysed using image processing techniques. A drawback of this method is that a drive motor and camera must be arranged for each carrousel position in order to enable the inspection of for instance 60,000 bottles per hour. The present invention provides a method for inspecting packagings for liquid medium, such as glass bottles optionally filled with beer or other drink, wherein the packagings are moved in line at predetermined speed and/or predetermined mutual spacing, and wherein images of the packagings are recorded by a number of cameras disposed adjacently of or successive to each other, and these images from the different cameras are combined in order to detect foreign substances therein. In the above stated PCT patent application the beer bottles are rotated and stopped. It is also conceivable, in any case theoretically but perhaps also practically, for movement of the liquid relative to the bottle to take place in a different way, for instance by causing the bottle to take a sharp bend one or more times at high speed. In the method as described in the above stated PCT patent application it has also been found that the value of the rotation speed is not very critical. This known device comprises a carrousel in which the bottles are clamped and wherein a camera is placed for each position. According to the present invention it is possible to envisage the- cameras being placed separately of the carrousel while the bottles move along in front of them. According to a further preferred embodiment of the present invention the bottles are transported in line and brought to pitch, rotated and stopped during the inline transport. On the successive cameras images can then be obtained of a packaging which are processed via a multiplexer, for instance subtracted from each other after some pre-processing, in order to enable detection of damage or loose particles such as glass splinters therein. In a further preferred embodiment use is made of synchronized cameras, although in another preferred embodiment it is possible to envisage operation with triggering and reset cameras, whereby the product is correctly positioned in each image. The present invention further provides a device for inspecting packagings, comprising: - transport means for advancing products in a substantially straight line; - a number of cameras disposed along the line for recording images of the packaging; and - a video-multiplexer to which the cameras are connected for the purpose of processing the successively obtained images of a packaging. In a further preferred embodiment the bottle packagings are rotated slowly along the cameras, for instance for recognition of the labels on the bottles. Further advantages, features and details of the present invention will be elucidated on the basis of the following description of a preferred embodiment thereof, with reference to the annexed drawing, in which: Fig. 1 shows a partly schematic view in perspective of a preferred embodiment of the present invention; Fig. 2 shows a side view from another angle of another embodiment according to the present invention; and Fig. 3 shows a block diagram of an embodiment shown in fig. 1 and 2. A number of beer bottles Bl, B2, B3 ... Bll is supplied on a feed conveyor 1, whereafter bottles B6-B11 are brought to pitch in a first part 2 of the preferred embodiment 3 of the present invention. Arranged on either side in this part 2 are conveyor belts 4, 5 to also cause the relevant bottles to rotate. The bottles are then transported to a position between two conveyor belts 6, 7, with which the rotating movement of the bottles is stopped and the glass splinters possibly present therein can be detected using cameras 11, 12, 13, 14, 15, which are each connected to a multiplex-unit 16. Light sources 21, 22, 23, 24 and 25 are situated under the bottles at which the cameras are directed. The cameras are directed at an angle of about 45° to the bottom of the bottles. In a preferred embodiment (not further shown) light sources 21-25 can be combined into a single light source. The rotation and subsequent stopping of this rotating movement and the detection of possibly present glass splinters on the basis of determined images is described in the above stated international patent application. An example of a light source for such a device, which makes use of for instance LEDs (Light Emitting Diodes) is described in applicant's non pre- published Netherlands patent application 1012323. As shown particularly in fig. 3, a number of central processing units (CPUs) are connected to video- multiplexer 16 to process a series of images of a bottle recorded by the cameras, and wherein the correct image is coupled to the correct product by making use of the video-multiplexer. In an alternative embodiment so-called intelligent cameras can be applied, wherein a part of the processing takes place at the camera, and wherein images are then for instance transferred from the one camera to the other without the intervention of a CPU. It is important that the bottles move along quickly enough in front of the cameras to enable the movement of the piece of glass to be recorded. The distance D between two cameras is as small as possible, for instance 10 cm, due to the size of the products. If there are ten cameras this will produce a length of the image system of 1 m and a minimal line speed of 2. m per second. A number of images corresponding to the number of cameras is recorded of each product. Operation can take place at a shutter speed of for instance 200 msec. Of each product there is recorded a number of images corresponding for instance with the number of cameras. As a starting point can for instance be taken 50 images (frames per second, or 100 fields) . In practice it would still be necessary for instance to test whether the images or fields must overlap or not, depending on the size of the camera and on the distance from the camera to the images of the packagings for recording. In the above described preferred embodiment use can be made of commercially available synchronized cameras, either in colour, or in black and white, and likewise obtainable frame-grabbers . The investments in hardware can be limited, while a compact system is provided which can be added to in modular manner, wherein the series of images of the same moving product is recorded. The present invention is not limited to the above described preferred embodiment; the rights sought are defined by the following claims, within the scope of which many modifications can be envisaged.

Claims: CLAIMS 1. Method for inspecting packagings for liquid medium, such as glass bottles optionally filled with beer or other drink, wherein the packagings are moved in line at predetermined speed and/or predetermined mutual spacing, and wherein images of the packagings are recorded by a number of cameras disposed adjacently of or successive to each other, and these images from the different cameras are combined in order to detect foreign substances therein. 2. Method as claimed in claim 1, wherein the packagings are moved and stopped, for instance rotated and brought to a standstill. 3. Method as claimed in claim 1 or 2 , wherein the packagings are advanced in line. 4. Method as claimed in claim 1, 2 or 3 , wherein the cameras are synchronized and connected to a video-multiplexer. 5. Method as claimed in one or more of the claims 1-4, wherein asynchronous reset cameras are applied which can be individually triggered. 6. Device for inspecting packagings, comprising: - transport means for advancing products in a substantially straight line; - a number of cameras disposed along the line for recording images of the packaging; and - a video-multiplexer to which the cameras are connected for the purpose of processing the successively obtained images of a packaging. 7. Device as claimed in claim 6, provided with first rotation means for causing the products to rotate along the line. 8. Device as claimed in claim 6, wherein second rotation means cause the products to rotate relatively slowly along the cameras. 9. Device as claimed in claim 7 or 8 , wherein the drive of the multiplexer is coupled to the feed conveyor.

Inventors: JOORDENS SERVAES, VAN DER STADT AREND, JOORDENS, SERVAES, VAN DER STADT, AREND
Applicants: EAGLE VISION SYSTEMS B V, JOORDENS SERVAES, STADT AREND V D, EAGLE VISION SYSTEMS B.V., JOORDENS, SERVAES, VAN DER STADT, AREND
Application year: 2001
Main classification: G01N21
IPC codes: G01N21