NL1012477C1 - Scanning equipment to detect contamination on the outside of hen's egg, uses reflections of rotating beam of light to build up electronic image - Google Patents

Abstract

The scanning equipment has a rotating mirror (3) which directs a beam of light from a source (2) onto a curved reflector (4). The beam scans the surface of the egg (E) and reflections are detected by a sensor (5). The sensor output is used to build up an electronic image which is then compared with a stored ideal image. If the differences between the scanned and stored image are great, it is an indication of contamination on the egg's surface.

Description

Method and device for detecting dirt on products or articles, such as eggs.

The present invention relates to a method and an apparatus for detecting dirt on products or articles such as eggs.

In particular, the invention relates to a method and an apparatus for selecting eggs on which dirt has been detected.

It is well known in the egg processing industry to test eggs and then select them based on a number of characteristics for which strict criteria have been laid down in the food trade. These characteristics mainly concern weight and fracture.

Due to the large scale on which eggs are now inspected, selected and, in particular, sorted, hygiene standards are increasingly tightened. Dirt on the shell of the eggs 20 plays an important role in this. Residues such as egg white or egg yolk residues, as well as residues from feces and otherwise, can cause unwanted infections and can therefore be very detrimental to hygiene during and after the egg treatment.

Accordingly, the criteria in the food industry 25 are also constantly being tightened.

Before removing any dirt on eggs it is necessary to detect this dirt adequately and to include this detection and subsequent removal in the sorting process if possible.

For a long time, as described in German patent DE 637956, candling or candling of eggs has taken place before the eggs are selected, for example, on sorting or packaging lines by weight.

This candling is performed by operators who each see the exposed eggs pass through and essentially recognize the eggs on which there is a crack or open fracture, either marking them afterwards automatically removed from the stream of 1012477-2 eggs or manually from the pick up flow. There are many shortcomings in this way of working.

Since many thousands of eggs pass through sorting processes, operators will have to alternate regularly during this tiring work. As a result, interpretation differences in brands and turnips cannot be avoided.

A further problem is the difference between white and brown eggs, with all shades in between, as well as the shell thicknesses. The recognisability of dirt, cracks and fractures can thus differ considerably.

Nevertheless, great experience makes recognizing, in particular, cracks and fractures reasonably reliable and successful.

The situation of dirt on eggs seems to be very similar to the above. However, it has been found that far more eggs are visibly contaminated than with the human eye. Protein stains are therefore hardly distinguishable. Moreover, many more eggs appear to be contaminated than damaged with cracks or breaks, so that it is virtually impossible to mark or remove them manually.

From US patent US 4,622,469 it is known to detect residues of spoiled protein originating from and present on broken or unbroken eggs with the aid of incident ultraviolet light, wherein said residues appear to fluoresce strongly. However, very large housings for combinations of UV-20 light sources and recording cameras are required to make the set-up a working whole, partly determined by the required adequate and heavy shielding when using UV light. This makes it considerably more difficult to place such installations in sorting stations or stables.

Furthermore, reference is made to US patent US 5,615,777, in which a number of laser sources positioned next to one another by means of laser beams illuminate the surfaces of eggs in order to detect cracks or breaks in eggs. Scanning takes place along lines each composed of a string of circles traversed by the rays which are intersected upon passing a crack or break. The light entering the crack or break is not reflected, but makes the egg light up briefly. This light-up is detected by a photodetector positioned to the side of the egg.

It has been found that with such an arrangement, dirt on the product such as an egg cannot be detected. Nor can fine cracks be observed. Moreover, the transmittance to such light in brown 1012477-3 eggs has been found to decrease such that the reliability of the results obtained leaves much to be desired.

In order to overcome the above-described problems, the present invention is characterized by a method comprising the following steps, 5 - exposing the eggs by scanning with a light beam, the light beam passing over the eggs along several lines, - recording reflections of a said light beam and determining reflection values, - composing an image of the exposed eggs from these reflections, the image being built up from pixels, and - determining image units in the image by comparing the reflection values with preset values reflection threshold values.

A further embodiment of the invention comprises a method for selecting articles or products, in particular eggs, on which there are defects, such as dirt, comprising, in addition to the steps indicated above, - comparing the image units in the image with those of a reference image which contains a unit limit for permissible amount of dirt, - determining eggs for which the said limit has been exceeded, - selecting the eggs for which the said limit has been exceeded, and - removing eggs after selection.

The present invention furthermore comprises a device for detecting, and also for selecting articles or products, in particular eggs, on which there are defects, such as dirt, comprising a device, such as an endless belt, for supplying and discharging the eggs to be selected and selected, respectively - a light source for illuminating the eggs placed in the container along a line with a light beam, - a device, such as a sensor, for recording reflections of the lines reflected by the eggs in the container placed eggs in which the image is built up of pixels or pixels, - an image processing device for determining a reflection value for each pixel, - a data processing device determining image units in the image by comparing the reflection values with preset reflection threshold values.

1012477-4 - a device for comparing the image units in the image with those of a reference image comprising a unit limit for permissible amount of dirt, - a device for determining eggs for which said limit has been exceeded, and 5 - a device for selecting the eggs for which said limit has been exceeded.

Experiments have shown that when dirt, or a crack or fracture passes through a scanning light beam, the intensity of the reflected signal differs significantly from the reflections of adjacent positions. Good detection and selection criteria can be established by suitable processing of these signals.

Disadvantages as mentioned above have thus been largely remedied. The difference between brown and white eggs appears to no longer play a role. Suitably, a barcode scanner for line scanning can be used for this purpose, in which the eggs are grouped on the sorting device and moved in rows on rolls of an endless belt and while moving the belt rotate about their axis with an X direction defined along a row and a Y direction perpendicular thereto.

In a further exemplary embodiment, the scanning by the light beam in the X direction is repeated a number of times along a corresponding number of lines shifted parallel in the Y direction to form a line pattern.

In a particular embodiment of the present invention, the light beam is shifted parallel by first being reflected to the egg via a first mirror rotating at an appropriate speed and then via at least a second mirror.

Surprisingly, it has been found that the transitions between the reflections are very sharp. Advantageously, therefore, the size of the units to be regarded as defects can be determined very accurately. This is very suitable for selection and sorting. If desired, thresholds and corresponding selection criteria can be applied.

The invention will be elucidated hereinbelow with reference to some exemplary figures. In these figures, corresponding parts or components are numbered the same.

Figures 1a and 1b schematically show the method and the device according to the present invention.

Figure 2 shows a scheme for signal processing.

Figures 3a and 3b show some examples of signals obtained by scanning egg surfaces along a line, a white egg and a brown egg, respectively.

In figure 1a, a scanning light beam 1 from a light source 2 in a housing 10 is guided via a rotating, for instance flat, mirror 3 and fixed curved mirrors 4 to an egg E passing underneath. The reflected light is received on a sensor 5, also in housing 10. In the case of sorting and selecting, the egg E is passed by rotating on a so-called roller conveyor.

On the eggs E a line pattern 6 as shown in figure 1b then arises, in which eggs of the same row are scanned or also scanned at different moments during rotation on the rollers, indicated by arrow R. This scanning 15 takes place suitably along, for example, 20 lines, but other numbers can also be chosen. By correct combination and positioning of mirror 3 and mirrors 4, the line patterns can also cover several rows of eggs, for example 3 rows, so that images of 3 by 3 eggs are recorded on the sensor surface of the sensor. In addition, additional reflectors can be arranged such that the two egg ends are also fully depicted.

A so-called barcode scanner can advantageously be used as a scanning sensor, shown here as light source 2 and sensor 5 in the same housing 10. Barcode scanners as well as their operation and properties are well known in the optical scanning art and will not be explained in further detail here.

The lines of line pattern 6 shown in Figure 1b are obtained in that the barcode scanner performs the scanning of the light beam along a line in the indicated X direction, while the rotating mirror 3 in combination with the mirrors 4 causes the parallel displacement of this line in the the indicated Y direction to 30.

Figure 2 shows how light beam 1 from housing 10 with light source 2, a laser light source, traverses a line 13 via a rotating octagonal mirror 12 such as one of the indicated lines of the line pattern 6 in the X direction in figure 1b.

10 1? / ”6

The light reflected from the egg falls on sensor 5, for example a photodiode, via a mirror placed sideways from mirror 12 and placed on sensor 5. The signal 20 obtained there is amplified in amplifier 21, after which noise is filtered out of the amplified signal 22 in filter 23. The signal 24 obtained there is transmitted from a central processing unit 25, for instance a control unit, via control lines 25a, b, c. microprocessor, further processed via the analog / digital converter 26 controlled by unit 25 into a digital signal 27, which is further processed in computer unit 28 into data stream 29. This data stream 29 is processed with a software program 30 such that both images of the egg surface as well as dirt spots or otherwise defined deviations such as cracks or fractures. The operations of data stream 29 will be explained in more detail below. Furthermore, a sorting device can be operated by means of signal 31 from unit 25 such that deviating eggs are removed from the flow of eggs in time. As seen in Figure 2, unit 15 also changes rotation frequency signals 312 and 303 of mirror 12 and mirror 3, respectively, in order to synchronize these rotations with the processing and processing of the signals recorded by sensor 5.

Figures 3a and 3b show examples of signals obtained by sensor 5 in which the scanning light beams have traversed a single line in the X direction and have not yet been filtered. The light rays from a barcode scanner as mentioned above are laser light rays with a wavelength of 670 nm. Reflections will decrease due to the defects. In these figures, the graduation along the horizontal axis is a measure of time, and thus of the distance across the egg surface, while vertically depicting intensities of the reflected signal. Due to the operations explained above, the defects are shown as peaks.

In figure 3a it concerns a line over a white egg. The distance over which the scanning light beam passes over the egg is indicated between two broken lines. Two dirty spots or dirt spots appear on this egg.

Figure 3b shows a similar picture for a brown egg.

It will be apparent from Figures 3 that after digitization in unit 26 and processing in unit 28, the data stream of digital signals is constructed in such a way that the analog intensities initially obtained via sensor 5 can be further compared as digital data with preset threshold levels. These levels 1012477-7 make dirty spots locatable per scanning line. Using the data for the entire line pattern 6 as shown in Figure 1b representing intensity values for each scanned point along a line on an egg surface, also referred to as pixels or pixels, an image of an egg surface is then assembled so that a landscape of deviating egg surface parts is visible is. Determination of total dirt surfaces, or "dark" surfaces where cracks or fractures have occurred, makes it possible to make a decision about whether or not to remove a scanned egg.

Such a decision can be made in an advantageous manner by comparing the image obtained with a reference image, for such reference images limits for maximum allowable sizes for image units such as dirt surfaces are indicated. A further possibility for making a decision can be made by taking a maximum total number of pixels for the image units as a reference. As soon as this total number is exceeded in the image obtained, the product, such as an egg, will be removed.

It will be clear to any person skilled in the art that other types of picture units, or also combinations of the above, can be taken.

Such an operation can be performed via software as indicated in figure 2 with number 30, whereby signal 31 can subsequently be generated in the central processing unit 25 to be passed on to a sorting unit coupled where appropriate.

A further advantage of the present invention is the inspection of eggs which have already been washed, whereby traces of visible or hardly visible dirt are traced.

The invention explained above can also be applied to articles and products other than eggs. This should in particular include food products such as fruits, vegetables and meat. In addition, one can think of sweets, or even toys.

It will be clear to everyone that minor deviations from the method and the device as described above are deemed not to exceed the scope of the appended claims.

10 1 2477-

Claims (13)

Method for detecting defects such as dirt on articles or products, in particular on eggs, comprising the following steps - exposing the eggs by scanning with a light beam, the light beam passing over the eggs along several lines, - recording reflections of a said light beam and determining reflection values, - composing an image of the exposed eggs from these reflections, the image being built up from pixels, and - determining image units in the image by measuring the reflection values compare with preset reflection threshold values. 15 A method for selecting articles or products, in particular eggs, on which there are defects, such as dirt, comprising the following steps - exposing the eggs by scanning with a light beam, wherein the light beam along several lines over the eggs, - recording reflections of a said light beam, - composing an image of the exposed eggs from these reflections, the image being built up from pixels, and - determining image units in the image by comparing the reflection values with preset reflection threshold values, - comparing the image units in the image with those of a reference image containing a unit limit for allowable amount of dirt, - determining eggs for which said limit has been exceeded, - selecting eggs for which said limit has been exceeded and 30. the removal of eggs after selection. A method according to claim 1 or 2, wherein images of the total egg surface are recorded for each egg. 101 24 77- The method of claim 1, 2 or 3, wherein the units are surfaces. 5 The method of claim 1,2 or 3, wherein the units are total numbers of pixels. 10 The method of claim 5, wherein the units are combinations of areas and total numbers of pixels. 01 2 * 77- 7. Device for detecting defects such as dirt on articles or products, in particular eggs, comprising - a holder for carrying eggs, - a light source for illuminating the placed in the holder with a light beam along several lines eggs, - a device, such as a sensor, for recording reflections of the lines reflected by the eggs placed in the holder, the image being built up from pixels or pixels, - an image processing device for determining a reflection value for each pixel, and - a data processing device determines image units in the image by comparing the reflection values with preset reflection threshold values. 8. Device for selecting articles or products, in particular eggs, on which defects, such as dirt, are present, comprising a device, such as an endless belt, for supplying and removing the eggs to be selected and selected, respectively, - a light source for illuminating the eggs placed in the holder with a light beam along several lines, - a device, such as a sensor, for recording reflections of the lines reflected by the eggs placed in the holder, the image being built up from pixels or pixels, - an image processing device for determining a reflection value for each pixel, - a data processing device determining image units in the image by comparing the reflection values with preset reflection threshold values. - a device for comparing the image units in the image with those of a reference image which comprises a unit limit for permissible amount of dirt, 30. a device for determining eggs for which the said limit has been exceeded, and - a device for selecting the eggs for which the said limit has been exceeded. The device of claim 8, wherein the eggs are grouped and moved in rows on rolls of an endless belt and rotate about their axis while moving the belt with an X-5 direction defined along a row and a Y direction perpendicular on that. 10. Device as claimed in claim 8 or 9, wherein a barcode scanner as a light source and sensor scans eggs 10 in a line with a light beam. 11. Device as claimed in claim 8, 9, or 10, wherein the scanning by the light beam in the X direction is repeated a number of times along a corresponding number of lines shifted parallel in the Y direction, thereby forming a line pattern. An apparatus according to claim 11, wherein the light beam is shifted in parallel by first being reflected to the egg via a first mirror rotating at an appropriate speed and then via at least a second mirror 20. The device of claim 12, wherein the second mirror is curved. 25 i 0 1? 4 7 7 '