GB2133873A

GB2133873A - Opto-electrical checking of packages

Info

Publication number: GB2133873A
Application number: GB08329031A
Authority: GB
Inventors: Charles Richard Williams
Original assignee: Schweizerische Industrie Gesellschaft
Current assignee: Schweizerische Industrie Gesellschaft
Priority date: 1983-01-20
Filing date: 1983-10-31
Publication date: 1984-08-01
Also published as: GB2133873B; GB8329031D0

Abstract

To check whether goods have been correctly packaged, each package P is brought into a specific position relative to an image transducer 23 or 33 by means of slide 20 or 30 and stop plate 21 or 31. By means of two image transducers 23 and 33 both end-faces of the package may be scanned in vertical lines during its movement. The information provided by the images, divided into grey levels and converted into digital impulses at 40 and 41, is compared at 42 and 43 with stored image data from 44, and this comparison is used by a processor 45 for determining whether the end folds of the package are defective. Rejected packages are removed from the conveyor line by means of an ejector 16. Pulses from a transmitter 15 on the conveyor are used at 46 to synchronise the image comparison with the packages. <IMAGE>

Description

SPECIFICATION Opto-electrical checking of packages The present invention concerns the optoelectrical checking of at least portions of packages for the purpose of eliminating defective packages.

OH-A 452 223 describes apparatus for detecting defects in a continuously moving web of material. For this purpose, photoelectric cells are provided in two rows arranged alongside each other, the photoelectric cells in one of the rows overlapping the light-sensitive areas in the other row so that no point on the web of material can move past the cells without being monitored. The presence of defects in the material is indicated by any changes in light-intensity that are detected.

GB-A- 2 083 214 discloses equipment for monitoring the width of objects, in particular biscuits, moving on a conveyor belt. For this purpose, a COD line-camera is arranged above the conveyor belt at an angle to the direction in which the belt moves. By synchronization, one scan per row of objects is sufficient. In addition, the state of bake of the biscuits can be monitored by observing the colour.

According to a data sheet "WEB/AF 8/81 md", issued by Messrs. Robert Bosch GmbH and relating to an S.A.M. sensor system for automation and measuring techniques, COD or CID line-cameras are known to be used for taking pictures. These serve to measure areas or lengths as well as to examine contours and for recognizing code signals or other data of this kind.

In the packaging industry, however, the most important factors to be monitored are not contours or colours, but the form and quality of folds in packages, since these -- among other factors-- serve as means for indicating whether the packing machines are operating correctly.

The object of the present invention is, therefore, to provide means for checking the package, whereby the folds and sealing seams, i.e. the arrangement of closure flaps, can be examined.

According to the invention, this object is achieved by a method of opto-electrical checking at least portions of packages for the purpose of eliminating defective packages, comprising moving each package on the conveyor means into at least one specific position relative to at least one opto-electrical transducer, producing an electronic image signal of at least one portion of that surface of the package located adjacent the opto-electrical transducer, comparing such electronic image signal with a corresponding stored image signal, and deriving from the comparison a signal for determining whether the package conforms to pattern.

The invention also concerns apparatus for performing the above method comprising a conveyor means for moving the packages, at least one first stop slide and an associated stop face on the conveyor means, at least one opto-electrical transducer downstream of the stopQface for providing brilliancy-dependent output signals, signal-converting means for forming dataprocessable image signals from the output signals, and a data processor with stores for comparing the converted output signals with corresponding stored signals and for providing an acceptance or rejection signal.

An embodiment of an apparatus for performing the invention will now be described by reference to the accompanying drawing which shows, in schematic perspective, the apparatus in relation to a conveyor belt, and a block circuit diagram of a switching system for operating the apparatus.

Packages P are moved on a continuously driven conveyor belt 10 comprising equidistantly arranged dogs 11, from a packaging machine, located to the left outside the drawing, to a collector located to the right and iikewise outside the drawing. The conveyor belt 10 is powered by an electric motor 1 3. Mounted on the drive shaft 14 of motor 13 is an angle transmitter 15 for synchronizing the installation. Provided at the downstream end of the conveyor belt 10 is an ejector 1 6 for removing defective packages P.

A first stop slide 20 with an oppositely arranged stop plate 21 serves to align the packages P in relation to the right-hand edge of the conveyor belt 10 as seen in the direction of flow. Located downstream of this first stop means is a first image transducer 23 which is set up to scan a vertical line along the package P moving past it.

Following this first image transducer is a second stop slide 30 with a stop plate 31, and a second image transducer 33. The package P is thereby aligned on the left-hand edge of the conveyor belt 10, and the second image transducer 33 scans the opposite face of the package likewise with a vertical linear image portion. Light sources 22, 32 are associated with the respective transducers 23, 33.

The image information in the form of an analogue signal is passed from the image transducers 23, 33 to respective analogue-digital transducers 40, 41 so as to divide up the information into different briliiancy stages. The digitalized information provided by the images is passed to image comparators 42, 43 each of which consists of a reading store 44 which contains corresponding information regarding a stored image, so that it can be determined whether the two images are identical. The result of this comparison of image is then passed to a process computer 45 which, in accordance with the programme, then decides whether an ascertained difference between the images is to be regarded as indicating a defective package or a permissible deviation.The result of this decision is passed in signal form to the ejector 16, which, in the event of a defective packaging, pushes the package P concerned off the conveyor belt 1 0.

Since the entire system can operate satisfactorily only if the synchronous operation is assured, the position at any given moment of the conveyor belt 10 and therefore also of the package is determined by means of the angle transmitter 15, and a synchronization stage 46 receives corresponding data. On the basis of these data and of the known arrangement of the various units of the equipment, the stage 46 can, at the correct moment, release control signals for the two image transducers 23, 33 and the image comparators 42, 43 as well as the read-out command for the reading store.

These circuit details are well known in dataprocessing techniques and do not therefore require to be described here.

The described arrangement permits, in particular, evaluation of the quality of the end folds of the packages in the form of grey stages. It is feasible for a plurality of image transducers to be arranged in succession, these each being provided with a colour filter so that differences in colour of the packages could be determined.

Claims

1. A method of opto-electrical checking at least portions of packages for the purpose of eliminating defective packages, comprising moving each package on the conveyor means into at least one specific position relative to at least one opto-electrical transducer, producing an electronic image signal of at least one portion of that surface of the package located adjacent the opto-electrical transducer, comparing such electronic image signal with a corresponding stored image signal, and deriving from the comparison a signal for determining whether the package conforms to pattern.

2. A method according to Claim 1, wherein one of two opposite sides of the package is first brought into a specific position relative to a first opto-electrical transducer, and then, after a complete image of this first side has been made, the opposite side is moved into a specific position relatively to a second opto-electrical transducer.

3. A method according to Claim 1 or Claim 2, wherein the or each opto-electrical transducer performs a linear scan in a plane which is at least approximately at right angles to the direction of movement of the packages.

4. A method according to Claims 2 and 3, wherein each opto-electrical transducer is set up for the differentiation of a plurality of grey scales.

5. A method according to Claim 3, wherein a plurality of opto-electrical transducers are arranged alongside each other, each being provided with a colour filter to enable colour difference on the package to be detected.

6. A method according to Claim 5, wherein each opto-electrical transducer is set up for differentiating a plurality of brilliances.

7. Apparatus for performing the method of Claim 1, comprising a conveyor means for moving the packages, at least one first stop slide and an associated stop face on the conveyor means, at least one opto-electrical transducer downstream of the stop face for providing brilliancy-dependent output signals, signal-converting means for forming data-processible image signals from the output signals, and a data processor with stores for comparing the converted output signals with corresponding stored signals and for providing an acceptance or rejection signal.

8. Apparatus according to Claim 7, comprising a second stop slide and an associated second stop face downstream of the first opto-electrical transducer, and a second opto-electrical transducer downstream of the first opto-electrical transducer, whereby a first face of each package can be brought to a certain distance from the first opto-electrical transducer by means of the first stop slide, and a face, opposite to this first face, can be brought to a certain distance from the second opto-electrical transducer by means of the second stop slide.

9. Apparatus according to Claim 7, comprising synchronizing means for ensuring correspondence in place and time of the individual image points that are scanned by the opto-electrical transducers on the packages moved past by the conveyor means and are compared with the stored image signal.

10. Apparatus according to Claim 9, wherein the synchronizing means comprises an angleposition transmitter for transmitting control impulses at least to the opto-electrical transducers to be synchronized.

11. The use of the method of Claim 1 for checking the end-face folding of the wrapping material.

12. A method of opto-electrical checking of packages, according to Claim 1 and substantially as hereinbefore described.

1 3. Apparatus for the opto-electrical checking of packages constructed, arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawing.