WO2010074572A1

WO2010074572A1 - Method and apparatus for classifying eggs

Info

Publication number: WO2010074572A1
Application number: PCT/NL2009/050796
Authority: WO
Inventors: Josse De Baerdemaeker; Bart De Ketelaere; Michiel Woittiez; Martine Wevers; Greetje Kerckhofs; Marjo De Krijger
Original assignee: FPS Food Processing Systems BV
Current assignee: FPS Food Processing Systems BV
Priority date: 2008-12-23
Filing date: 2009-12-23
Publication date: 2010-07-01
Anticipated expiration: 2011-06-23

Abstract

A method for classifying eggs, which eggs each possess different parts (10, 20, 30), namely an egg shell (10), egg fluid (20) and an air cell (30), the method comprising: - candling each egg (E) to obtain at least one image of the egg (E), such that the different egg parts (10, 20, 30) are distinguishable in the image; and - processing the at least one image to classify the egg (E).

Description

Title: Method and apparatus for classifying eggs.

The present invention relates to a method and apparatus for classifying eggs.

A method of this type is known, for example from JP2000-266695. In this document, it is described in what way the presence of eggshell residues on and in boiled eggs can be established using X-rays. In succession, with a conveyor the eggs are passed along two radiation sources, transmission images are made, the images are analyzed, and the possible presence of an eggshell residue is established. On the basis of this, the eggs can be sorted. Further, the candling of eggs is weD known in the technology of sorting and packaging eggs, in particular the candling of shell eggs. The eggs, generally disposed on and between two carriers (mostly diabolo-shaped rollers) of a conveyor, are passed through a chamber, protected to some extent from outside incident light, where the eggs are illuminated from below, so that particularly cracks in these eggs can be visually observed. The observer, i.e., an operator of such a sorting machine and typically called candler, either marks such eggs for them to be removed from the stream later on, or picks them up directly from the egg stream by hand and puts them aside. Such a candling process is often automated, as described in, for example, EP330260. In further developments in this field of technology, more particularly food technology in combination with transporting and sorting, research efforts are directed towards modes of handling the products, e.g. fruits or eggs, whereby transfer and engagement are minimized, in particular with a view to improving hygiene. A clear example of this is described in EP1871670, where, with grippers mounted on a drum that rotates above such a sorting track, only those eggs that stand a dirt test are picked up to be rotated in the proper direction. The result is that dirty eggs are not picked up but are immediately discharged off the conveyor via a gutter. For classifying eggs by weight, there is known from applicant's EP1062485 an apparatus for weighing eggs on such a sorting machine, where the eggs are picked up by grippers, are then weighed, and are put back again. More particularly, the grippers are connected with a sliding device which is slid over a weighing cell to carry out the weighing. This construction constitutes an improvement especially where the hygiene of the sorting process is concerned, because the assembly of weighing cells is no longer polluted by all the successive eggs rolling over them.

In EP1856971 an apparatus is described for counting, using cameras, eggs that have just been laid and are discharged from the henhouses. With this technique, it is additionally possible, with the aid of a reference value on the one hand and the contours on the other, to determine, besides the volume, the mass of an observed egg. For this purpose, use is made of light having wavelengths in the visible and infrared region. Against the background of the above technology, a detection method has been sought that is capable of examining products such as eggs for particular properties and that is' suitable for apparatuses and methods in such sorting machines and results in considerably improved hygienic conditions. More particularly, for such products, research has been done into a method for both high -precision and non-contact weighing.

To resolve the above problem, the present invention provides a method for classifying eggs, which eggs each possess different parts, namely an eggshell, egg fluid and an air cell, the method comprising: - candling each egg to obtain at least one image of the egg, such that the different egg parts are distinguishable in the image; and

- processing the at least one image to classify the egg, for example, utilizing a suitable processing unit.

It has been found that with this method eggs can be classified very

' - ϊ \ • accurately in a highly advantageous and convenient manner. Thus, weights of eggs can be established very accurately. Any form of contact other than by a conventional holder can be avoided, more particularly where the eggs are disposed on rollers of an endless roller conveyor. To those skilled in the art, it will be clear that fouling of grippers is thus wholly avoided. This method is very^: suitable, for example, for sorting eggs on a sorting machine with endless roller conveyor. Furthermore, to great advantage, handling and transporting eggs with the aid of grippers entailing a chance of fouling is avoided.

In particular, the invention can comprise exposure to very short wave electromagnetic radiation (in particular X-rays).

According to a further elaboration, the method comprises candling the egg in different positions of the egg, to obtain different images of the egg, wherein the different images are processed to classify the egg, wherein the egg is preferably candled in at least three different positions. The method preferably comprises rotating each egg with respect to a candling radiation source.

According to a further elaboration, the at least one image can be processed to determine surfaces of the egg parts, for the purpose of egg classification. Further, it is particularly advantageous when the volume of the air cell of the egg is determined by processing the at least one image, for example, to classify the egg by age.

Furthermore, the volume of the egg fluid of the egg may be determined by processing the at least one image. According to a further elaboration, the at least one image is processed utilizing reference values, such that therewith the masses of each of the egg parts of the egg are determined. According to an extra advantageous elaboration, the mass of the egg is determined by processing the at least one image, in particular by determining the masses of each of the egg parts (for example, by determining the mSass of the shell as well as the mass of the egg fluid, and utilizing associated reference values). Further, it is found that the mass of the egg can be used to determine the strength of the eggshell.

According to an embodiment, the method for classifying eggs comprises: - exposing the eggs to electromagnetic radiation having a wavelength of at most 5 nm and therewith candling the eggs,

- recording imagesthat are obtained from differences in intensity of radiation transmitted by the eggs during candling,

- processing these images, whereby at least transitions and/or features derived therefrom in mainly density are established, whereby transition data are obtained,

- comparing the transition data with pre-set criteria, whereby comparative data are obtained,

- classifying the eggs on the basis of at least the comparative data. Further embodiments of the method have the feature, that the transitions and/or the features derived therefrom concern the eggshell; that the transitions and/or the features derived therefrom concern the air cell; . ' ^l \ i-.j. . . that the eggs are classified by their mass; that the eggs are classified by their age; that the eggs are classified by their eggshell strength; that the electromagnetic radiation comprises substantially x-ray radiation of the line spectrum type; that the electromagnetic radiation comprises substantially x-ray radiation of the continuous spectrum type; that the electromagnetic radiation comprises x-ray radiation of both the continuous spectrum and of the line spectrum type; that during candling of the eggs at least a single image of a single well-defined side is recorded; that the eggs, when recording images through candling, are rotated about a well-defined axis; and that the eggs lie on rotating rollers of an egg sorting machine.

Further, the present invention concerns a method for sorting eggs wherein the eggs are classified with a method provided by the invention.

The present invention furthermore relates to an apparatus for classifying eggs, comprising:

- candling means for generating at least one image of each egg, such that different egg parts are distinguishable in the image; and - processing means for processing the at least one image to classify the egg.

Good results are obtained when the candling means comprise an X-ray source and a camera.

Furthermore, the apparatus is preferably provided with means of rotating the eggs, to obtain different images at different egg orientations of each egg. Such means may comprise, for example, rollers of an egg conveyor.

An example of an apparatus for classifying eggs comprises:

-an X-ray radiation source for exposing the eggs to X-ray radiation having a wavelength of at most 5 nm and therewith candling the eggs, -a camera system with at least a single camera for recording images of the eggs that are obtained from differences in intensity of radiation transmitted by the eggs during candling, and

-a processing unit for processing these images, wherein at least transitions and/or features derived therefrom in mainly density are established, wherein the eggs are classified on the basis of at least the transitions and/or derived features.

More particularly, the apparatus has the feature, that images are obtained of eggs in different positions of the eggs with respect to the X-ray radiation source; and that the eggs are rotated.

According to a further aspect, the present invention relates to a sorting apparatus for eggs that includes an apparatus for classifying eggs as mentioned and described above. The sorting apparatus is then preferably provided with an endless conveyor with rollers to carry (and, for example, rotate) the eggs.

More in detail, the invention is described below with reference to a drawing, wherein Figure 1 shows a diagram of an exemplary embodiment of an apparatus according to the present invention, and wherein Figure 2 shows an image of an egg that has been recorded using the method according to the present invention.

Fig. 1 shows an example of an apparatus for classifying eggs E, which eggs each possess different parts 10, 20, 30, viz, an eggshell 10, egg fluid 20 and an air cell 30 (the egg parts are visible in the image shown in Fig. 2). The apparatus comprises candling means 1, 4, 5 to generate (by means of egg candling) at least one image of each egg E, such that different egg parts 10, 20, 30 are distinguishable in the image. Furthermore, the apparatus is provided with processing means 6 for processing the at least one image to classify the egg E. In the example, the candling means comprise an X-ray radiation source 1 (for example, with a radiation beam modulator 2) to generate radiation X, and a camera 4 to generate the at least one image.

During use, the apparatus can carry out a method for classifying eggs, the method comprising: candling each egg to obtain at least one image of the egg, such that the different egg parts are distinguishable in the image; the method further comprising: processing the at least one image to classify the egg. The following provides a more detailed description of the example.

In Fig. 1, X-ray radiation X (for example, a beam) coming from a source 1 with radiation beam modulator 2 is incident on an egg E placed in a holder 3. On a screen 5 of a camera 4 having therein a signal processing unit 6, the radiation transmitted by the egg is captured and processed, respectively. It will be clear that the source and each camera may be designed in different ways. The same holds for the processing unit 6.

It will be clear to anyone skilled in the art that such a radiation beam modulator 2 can modulate the beam in multiple ways, where corresponding modulation units well known in the art will be used. Such modulation can relate to the wavelength to be chosen, the beam width and/or beam angle to be chosen, as well as the signal shape to be chosen.

For the wavelength, when a well-defined wavelength value is chosen, use will be made of monochromators used in this technology, more particularly solid state devices. In addition, so-called beam hardening, familiar to those skilled in the art,, will be used, i.e., the source is screened off by, for example, a small plate of a well-defined metal, that transmits a corresponding part of the resultant spectrum. For setting angles and widths of such a beam, in a manner familiar to those skilled in the art, for example, the desired types of diaphragms may be used.

Regarding the beam signal shape, it is to be noted that in most cases time-exposures are made to bring out the density differences sufficiently clearly. However, use may be made of time -varying beams, or even time- interrupted beams, for example, to be able to monitor differences between the recordings.

While in the depicted setup the egg E is placed in a rotary holder, eggs lying on rollers of a sorting- machine as mentioned above will make the same method possible.

In Fig. 2 there is shown an image or recording of an egg exposed to X-ray radiation, with the egg E, as indicated in Fig. 1, placed vertically in a holder 3. In this experiment the egg E is rotated in steps of 5°. For each angle, durations of exposure, referred to here as exposure times, between 30 and 90 ms were used. The total experiment lasted about 10 minutes. The base on which the egg E rests is manufactured from material that is substantially transparent to such X-ray radiation, for example, rubber or polystyrene foam.

The X-ray radiation source used was a Philips HOMX 161 device, with acceleration voltages for the electrons between, approximately, 1 and 90 kV, at a current of 0.39 rnA, with the source being designated as reflection source with continuous spectrum. The thus obtained beam is filtered by a small plate from aluminum, with an intensity peak around an energy of 10 keV being obtained. The corresponding wavelength range in this experiment runs approximately from 0.02 to 2 nm.

To be clearly seen on these recordings, due to density differences, are different parts of the egg, yyiz. the^ eggshell 10, the egg fluid 20 which is a composite of mainly egg white and egg yolk, and the air cell 30. The ability to distinguish these parts is precisely what makes it possible, in contrast with the above-mentioned EP1856971, to determine a very accurate value for the mass of such an egg. This approach makes it possible to apply the method according to the present invention in sorting machines that require high accuracies in sorting and packaging. In particular, these accurate mass determinations make it possible to comply with the required combinations of masses in larger packages, and especially the limitations imposed thereon.

More in detail, this image has been obtained with a CCD camera, of the type Adimec MX12P, with a resolution of 1024 by 1024 pixels on a surface of 182 mm square.

By the use of well known processing methods for gray scales, the surfaces of the egg parts on the^{^}iinage could be determined.

With these, thereupon, applying considerations of mathematical symmetry, the content of these parts was determined.

Finally, with reference values matching each of the parts, the mass of the egg was composed from the masses of constituent parts. It is noted that the terms mass and weight are interchangeable in this connection.

To those skilled in the art, it will be clear that the number of images made of an egg, where it is accurately known in what direction the egg axes are positioned in the beam, yields different levels of accuracy. It has been found that with at least three images an accuracy for the mass determination is achieved that is similar to that according to the conventional weighing procedures.

With the obtained images, also further parameters of eggs may be measured. In particular, the magnitude of the air cell is a measure of the age of the egg, and hence of the quality of the egg.

Furthermore, through combination of data, for example, by determining the mass according to the present invention and elasticity according to the techniques as described in EP1238582 and NL1018940, the strength of the eggshell can be determined. Thus, a next quality parameter besides age, mentioned above, is determined.

It will be clear to those skilled in the art that with the apparatus according to the present invention both food quality and food hygiene are effectively improved.

Claims

1. A method for classifying eggs, which eggs each possess different parts (10, 20, 30), namely an eggshell (10), egg fluid (20) and an air cell (30), the method comprising:

- candling each egg (E) to obtain at least one image of the egg (E), such that the different egg parts (10, 20, 30) are distinguishable in the image; and

- processing said at least one image to classify the egg (E).

2. A method according to claim 1, comprising:

- candling the egg (E) in different positions of the egg (E), to obtain different images of the egg (E), wherein the different images are processed to classify the egg.

3. A method according to'elaim 1 or 2, comprising: rotating each egg with respect to a candling radiation source (1).

4. A method according to any one of the preceding claims, wherein the egg (E) is disposed in a rotating holder or on rotating rollers, for example, rotating rollers of an egg sorting machine.

5. A method according to any one of the preceding claims, wherein the at least one image is processed to determine surfaces of the egg parts, for the purpose of classification.

6. A method according to any one of the preceding claims, wherein the volume of the air cell (30) of the egg (E) is determined by processing the at least one image, for example, to classify the egg by age.

7. A method according to any one of the preceding claims, wherein the volume of the egg fluid (20) of the egg (E) is determined by processing the at least one image.

8. A method according to any one of the preceding claims, wherein the at least one image is processed utilizing reference values, such that by the processing the masses of each of the egg parts (10, 20, 30) of the egg (E) are determined.

9. A method according to any one of the preceding claims, wherein the mass of the egg (E) is determinediby processing the at least one image, in particular by determining the masses of each of the egg parts (10, 20, 30).

10. A method according to claim 9, wherein said mass of the egg is used to determine the strength of the eggshell.

11. A method according to any one of the preceding claims, wherein electromagnetic radiation having a wavelength of at most 5 nm is used to candle the eggs, for example:

- substantially X-ray radiation of the line spectrum type; or

- substantially X-ray radiation of the continuous spectrum type; or

- X-ray radiation of both the continuous spectrum and of the line spectrum type.

12. A method for sorting eggs, wherein the eggs are classified with a method according to any one of the preceding claims.

13. A method according to "claim 12, wherein use is made of a sorting apparatus with rotating rollers to carry the eggs.

14. An apparatus for classifying eggs, which eggs each possess different parts (10, 20, 30), namely an eggshell (10), egg fluid (20) and an air cell (30), the apparatus comprising:

- candling means (1, 4, 5) for generating at least one image of each egg (E), such that different egg parts (10, 20, 30) are distinguishable in the image; and - processing means (6) for processing said at least one image to classify the egg (E).

15. An apparatus according to claim 14, wherein the candling means comprise an X-ray radiation source (1) and a camera (4).

16. An apparatus according to claim 14 or 15, provided with means of rotating the eggs, to obtain different images of each egg at different egg orientations.

17. A sorting apparatus for eggs comprising an apparatus for classifying eggs according to any one of claims 14-16, wherein the sorting apparatus is preferably provided with an endless conveyor with rollers to carry the eggs.