EP0736339B1 - Analysis device for automatically sorting products, especially fruit or vegetables - Google Patents

Description

The invention relates to a device analysis for automatic sorting of products, in particular fruits or vegetables.

There are many techniques to analyze products such as fruit or vegetables, to allow sorting automatic of these products in order to obtain batches homogeneous both in quality and in coloring.

A first technique consists in having one or more camera (s) above and / or on the side of a conveyor so as to analyze a portion of the surface of fruits or vegetables transported on it. However, this solution leads to a significant error rate because only a portion of the product surface is analyzed. As a result, the shortcomings of these products on non-visible sides are not taken into account when sorting.

To overcome this drawback, a solution consists of having four cameras distributed around a conveyor, at its junction with another conveyor raised above the latter, so as to analyze the fruits when they fall. This solution allows, in fact, analyze most of the product surface. However, and first of all, this solution does not allow analyze all of the top and bottom faces some products. In addition, dropping the products constitute a significant risk of trauma of these.

Another technique, very commonly used, consists of placing a camera above the conveyor, and to cause the product to turn on itself with high speed, to the right of this camera. As the previous, this solution allows to inspect the major part of the product surface. However, due to the high rotational speed to which the products, the risks of trauma of these are non negligable.

To overcome all of these disadvantages, other solutions have been proposed, consisting for example of suspending the products or transport on a transparent conveyor. However, in in practice, these solutions have proven to be unusable.

Another technique described in the patent EP 258 810 consists in placing a camera above the conveyor, a plurality of mirrors distributed above and on the sides of this conveyor so as to allow the camera to view the upper side and the faces side of the products, and a plurality of lamps lighting distributed above the conveyor. Apart from the underside of products resting on the conveyor, this solution therefore makes it possible to analyze most of the surface of said products without risk of trauma to these latter. However, the implementation of such technique is relatively complex. Indeed, this implementation requires in particular to have the lamps lighting so as not to dazzle the camera, provision which proves difficult to obtain if one wishes get uniform lighting. Likewise, the positions relative of the camera and the different mirrors must be perfectly defined, which is not very obvious from the has congestion problems related to the presence of conveyor. Furthermore, the adopted principle of use a CCD camera cut into analysis segments leads to a significant reduction in the resolution of the sensor.

Patent application WO-8906782 describes finally another technique using a device of analysis according to the characteristics of the preamble of the claim 1 of this application. However, this technique does not allow to analyze the underside of products.

The present invention proposes to overcome all the disadvantages of the above techniques described and its main objective is to provide a device for analyzing the products of an implementation and very simple operation, allowing, in addition, analyze the entire surface of these products without risk of trauma to them.

To this end, the invention relates to a device of analysis according to the characteristics of the preamble of the claim 1, further comprising second means reflection, called lower, arranged under the conveyor so as to intercept a portion of the light line reflected by the lateral reflection means and at allow to illuminate the underside of the products.

The principle of the invention therefore consists in generate a light line transversely scanning the surface of the conveyor, to deflect this light line, when of this scan, so as to successively illuminate the the entire periphery of the products, and for each point of said light line, to be obtained by means of reception arranged on the same optical axis as that of incident beam, information representative of the light energy backscattered by said point.

Such a device therefore makes it possible to carry out a plurality of data acquisitions as and when movement of products, including processing IT has no complexity. AT by way of example, but not limited to, this treatment can be carried out by means of a unit such as described in patent application FR 2,703,932.

Similarly and by way of example, the invention can be applied to the sorting of products transported on a calibrator of the type described in the request for French patent n ° 95.02223 filed on 21.02.95 in the name of the plaintiff, whose conveying fingers are particularly suitable for viewing optimal external surface of the products.

According to another characteristic of the invention, the deflection means are adapted for that a portion of the light line directly illuminates one of the side faces and a portion of the face upper products, side reflection means extending substantially vertically on the side of the conveyor so as to allow lighting on the other side side of the products.

This provision limits advantageously the lateral dimensions of this device of analysis.

For the same purpose, the means of diversion are preferably arranged substantially above the conveyor, intermediate reflection means being disposed between said deflection means and the means of lateral reflections so as to deflect the light line and to allow, on the one hand, direct lighting of a portion of the surface of the products and, on the other hand, a projection from a portion of the light line to the means of lateral reflections.

These intermediate means of reflection advantageously further comprise a reflector oblique arranged so as to deflect the light line in direction of a lateral reflection means, and a reflector lateral disposed so as to project said light line towards the products and the other means of lateral reflection.

Given its design and small footprint, such an analysis device can be used to equip conveyors with two lines parallel conveyors. For this purpose, and according to another characteristic of the invention, this analysis device includes unique deflection means common to both conveyor lines, and reflection means arranged symmetrically with respect to the longitudinal axis of said conveyor.

In this case, moreover, according to another characteristic of the invention, the means of reflection lateral respectively disposed on either side of the conveyor have a height suitable for, on the one hand, at the level of their lower part, allow to illuminate laterally the products transported on the line juxtaposed conveying and, on the other hand, at their upper part, act as side reflector intermediate for the other conveyor line.

Furthermore, the analysis device according to the invention preferably comprises means for ancillary reflection arranged to intercept the portion of light line adapted to directly illuminate products, so that the optical path of said portion of light line is of the same order of magnitude as those portions of the light line projected towards the means lateral and lower reflection.

These additional means of reflection allow to bring back the virtual image of the surface portion illuminated directly at a distance comparable to the images virtual portions of the surface illuminated by through the lateral reflection means and lower. Therefore, the different virtual images are grouped inside a depth of relatively small field.

Furthermore, according to another characteristic of the invention, the analysis device comprises at least two lighting means, and means optics capable of mixing the incident beams delivered by the different lighting means, these optical means being, moreover, advantageously constituted, for each lighting means, a polarizing cube.

For example, the lighting means can thus include a laser source suitable for deliver a multi-beam wavelength beam preselected, and a light source capable of generating a polarized monochromatic beam, such as those described in French patent application No. 2,703,932, as well as a near infrared laser source such as described in French patent application No. 95.02402 filed on 24.02.95 in the name of the plaintiff.

• la figure 1 est une vue schématique d'un dispositif conforme à l'invention,
• et la figure 2 est une vue d'un produit analysé au moyen d'un dispositif conforme à l'invention, sur laquelle son délimitées les trois zones de surface analysées.

Other characteristics, objects and advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings which represent, by way of non-limiting example, a preferred embodiment. On these drawings which form an integral part of this description:

• FIG. 1 is a schematic view of a device according to the invention,
• and Figure 2 is a view of a product analyzed by means of a device according to the invention, on which its delimited the three surface areas analyzed.

The analysis device in accordance with the invention shown in Figure 1 is arranged above a double conveyor line for a grading machine such as described in French patent application No. 95.02223 filed on 21.02.95, including an endless chain 1 carrying two series of conveying fingers 2, 3 arranged in opposite on either side of said chain.

• un premier ensemble comportant une source laser multiraies 4 (diodes ou laser multiraies) dont le faisceau est délivré par l'intermédiaire d'un miroir de renvoi 5 vers un cube polariseur 6 distinguant les faisceaux aller et retour. Ce premier ensemble comporte, en outre, des moyens d'acquisition schématisés en 7 conformes à ceux décrits dans la demande de brevet français FR 2.703.932,
• un deuxième ensemble comportant une source laser 8 constituée d'une diode laser collimatée proche de l'infrarouge dont le faisceau est délivré par l'intermédiaire d'un miroir de renvoi 9 vers un cube polariseur 10 distinguant les faisceaux aller et retour. Ce deuxième ensemble comporte, en outre, des moyens d'acquisition schématisés en 11 conformes à ceux décrits dans la demande de brevet français n° 95.02402,
• un troisième ensemble constitué d'un télémètre comportant une diode laser infrarouge 12 collimatée dont le faisceau est délivré par l'intermédiaire d'un miroir de renvoi 13 vers un cube polariseur 14 distinguant les faisceaux aller et retour. Ce troisième ensemble comporte, en outre, une chaíne d'acquisition schématisée en 15 conforme à celle décrite dans la demande de brevet français FR 2.703.932.

This analysis device comprises, firstly, sources of lighting of the products and means for receiving the backscattered light energy, shown diagrammatically on a reduced scale in FIG. 1, and constituted in the example of three compliant assemblies to those described respectively, on the one hand, in French patent application FR 2,703,932 and, on the other hand, in French patent application n ° 95.02402 filed on February 24, 95, namely:

• a first assembly comprising a multi-line laser source 4 (diodes or multi-line laser), the beam of which is delivered by means of a deflection mirror 5 towards a polarizing cube 6 distinguishing the outward and return beams. This first set also includes acquisition means shown diagrammatically in 7 in accordance with those described in French patent application FR 2,703,932,
• a second assembly comprising a laser source 8 consisting of a collimated laser diode close to infrared, the beam of which is delivered by means of a deflection mirror 9 to a polarizing cube 10 distinguishing the outward and return beams. This second set comprises, in addition, acquisition means shown diagrammatically in 11 in accordance with those described in French patent application No. 95.02402,
• a third assembly consisting of a range finder comprising a collimated infrared laser diode 12 whose beam is delivered via a deflection mirror 13 towards a polarizing cube 14 distinguishing the outward and return beams. This third set comprises, in addition, an acquisition chain shown schematically in 15 in accordance with that described in French patent application FR 2,703,932.

• une lame dichroïque 16 associée au premier ensemble et adaptée pour dévier les longueurs d'onde inférieures à 700 nanomètres,
• une lame dichroïque 17 associée au deuxième ensemble et adaptée pour dévier les longueurs d'onde inférieures à 800 nanomètres,
• et une lame dichroïque 18 associée au troisième ensemble et adaptée pour dévier les longueurs d'onde inférieure à 1 micron.

The incident beams delivered by the three light sources 4, 8, 12 are, moreover, delivered to dichroic plates capable, on the one hand, of superimposing said beams and, on the other hand, of deviating lengths of selected wave and be transparent for other wavelengths:

• a dichroic plate 16 associated with the first set and adapted to deflect wavelengths less than 700 nanometers,
• a dichroic plate 17 associated with the second set and adapted to deflect wavelengths less than 800 nanometers,
• and a dichroic blade 18 associated with the third set and adapted to deviate the wavelengths less than 1 micron.

The superimposed beam from the sources lighting 4, 8, 12 is itself delivered to a polygon turn 19 with facets capable of reflecting said beam and generate light lines, said polygon being associated with rotating drive means around an axis parallel to the direction of travel of the grader. Such a rotating polygon 19 is for example adapted so that the angle at the top of the scan is around 60 degrees, of which only about 32 degrees will be used.

The analysis device further comprises reflection means capable of deflecting the light line generated by the rotating polygon 19 so as to illuminate successively the entire surface of the products transported on the two conveyor lines 2, 3. It is note that in Figure 1 and for clarity, only the optical path allowing the analysis of the products carried by one of the conveyor lines 3 is shown. However, the analysis of the products carried by the other line of conveying 2 is obtained identically along a path optics symmetrical to that shown, during rotation of the rotating polygon 19.

The means of reflection include, in first place, two mirrors 20, 21 forming an open dihedral downwards of a plane angle substantially equal to 60 degrees, whose edge is arranged horizontally in the plane of vertical symmetry of the grader.

These means of reflection include, in in addition, two side mirrors 22, 23 arranged vertically on either side of the grader and extending substantially over a height between the fingers of conveying 2, 3 and the edge of the mirrors 20, 21.

The means of reflection include also, for each conveyor line 2, 3, two sets of mirrors 24, 25 and 26, 27 interposed between the central mirror 20 (or 21) and a lateral mirror 22 (or 23) so as to lengthen the optical path of the portion of the light line directly illuminating the products. (It is note that in figure 1, only mirrors 24-27 arranged above the conveyor line 2 are represented, it being understood that two similar sets are arranged symmetrically on top of each other conveyor line 3).

As shown in Figure 1, each of these sets is composed of two mirrors 24, 25 and 26, 27 forming a right dihedral with a horizontal edge, a said mirrors 24, 26 of each of these sets extending vertically and the other mirror 25, 27 extending horizontally.

In addition, these two sets are offset laterally and vertically, the set 24, 25 most close to the side mirror 22 being located substantially at a same height as the central mirror 20, and the other set 26, 27 lying below said mirror central.

The means of reflection include, finally, two lower mirrors 28, 29 each arranged under a conveyor line 2, 3 and adapted to illuminate the face lower products. As shown in Figure 1, these mirrors 28, 29 are inclined at an angle of the order of 30 degrees from the horizontal to face to the corresponding side mirror 22, 23 and to intercept a portion of the light line reflected by the latter.

As shown in Figure 2, the arrangement of these reflection means, the width of which is of the order of a few tens of millimeters, allows to successively illuminate three areas of the surface of produced during the rotation of the rotating polygon 19: a first zone 1 lit by mirrors side 22, 23, a second zone 2 lit by through the side mirrors 22, 23 and the mirror lower 29, and a third zone 3 directly lit after reflection by mirrors 24-27 and the mirror lateral 22.

In addition, these areas have portions that can potentially be processed by calculation so as to avoid the accumulation of the same defect, guaranteeing the analysis of the entire surface of products.

Such an analysis device allows acquire, during each scan, a series of signals analog (e.g. 128 analog signals for each zone of the product), triggering the start of a cycle being for example controlled by means of a cell.

In addition, the scanning speed (achieved in a time of the order of 66 microseconds) allows a large number of data acquisitions for each product (for example 128 acquisitions of signal sequences analog).

These analog signals are then processed by calculation, for example in accordance with processing algorithms described in the requests for patent FR 2,703,932 and n ° 95.02402, by means of a treatment preferably presenting two levels of memory allowing, at first, to acquire all the data corresponding to two products arranged opposite, then, in a second step, process this data during the following acquisitions.

Claims (11)

1. Analytical device for automatically sorting products, in particular fruit or vegetables moving longitudinally on a conveyor provided with supports (2, 3) for the said products adapted so as to mask as little as possible the lower face of the latter, the said sorting device comprising :

   spot lighting means (4, 8, 12) able to generate a polarized incident beam,

   means (19) for deflecting the polarized incident beam capable of causing the said beam to scan the upper surface of the conveyor along a transverse luminous line with respect to the direction of progress of the said conveyor,

   first, so-called lateral, means of reflection (22, 23) disposed laterally with respect to the conveyor so as to intercept a portion of the luminous line and to enable the products to be illuminated laterally,

   means of separation (6, 10, 14) aligned on the optical axis of the polarized incident beam and adapted so as to separate the said incident beam and the depolarized luminous energy scattered back by the products and the means of reflection (22, 23, 28, 29),

   an acquisition line (7, 11, 15) including sensors disposed so as to receive the backscattered luminous energy, and adapted so as to deliver representative analogue signals of the luminous intensity of the said point, for each point of each luminous line,

   and a processing unit having means for analogue/numeric conversion adapted so as to receive analogue signals coming from the sensors and so as to convert the said signals into series of numerical values, and calculating means adapted for calculating, from the pre-defined programmed criteria, usable sorting information,

   this analytical device being characterized in that it includes second, so-called lower, means of reflection (28, 29) disposed under the conveyor so as to intercept a portion of the luminous line reflected by the lateral means of reflection (22, 23) and to enable the lower face of these products to be illuminated.
2. Analytical device according to claim 1 characterized in that the means of deflection (19) are adapted so that a portion of the luminous line, after reflection by one of the lateral reflection means, directly illuminates one of the lateral faces and a portion of the upper face of the products, the lateral means of reflection (22, 23) extending substantially vertically over the side of the conveyor so as to enable the other lateral face of the products to be illuminated.
3. Analytical device according to either of claims 1 or 2, characterized in that the means of deflection (19) are disposed substantially above the conveyor, intermediate means of reflection (20, 21) being disposed between the said means of deflection and the lateral means of reflection (22, 23) so as to divert the luminous line and to enable, on the one hand, after reflection on one of the lateral means of reflection, a portion of the surface of the products to be illuminated directly and, on the other hand, to enable a portion of the luminous line to be projected towards the said means of reflection.
4. Analytical device according to claim 3, characterized in that the intermediate means of reflection comprise an oblique reflector (20, 21) disposed so as to deflect the luminous line in a direction of a lateral means of reflection (22, 23), and a lateral reflector (23, 22) disposed so as to project the said luminous line towards the products and the other lateral means of reflection.
5. Analytical device according to one of claims 3 or 4, for conveyors having two parallel conveyor lines (2, 3), characterized in that it comprises single means of deflection (19) common to the two conveyor lines, and means of reflection (20-23, 28, 29) disposed symmetrically with respect to the longitudinal axis of the said conveyor.
6. Analytical device according to claims 4 and 5, taken together, characterized in that the lateral means of reflection, (22, 23) disposed respectively either side of the conveyor have a height adapted so that, on the one hand, at the level of their lower part, to enable the products conveyed on the juxtaposed conveyor line (2, 3) to be illuminated laterally and, on the other hand, at the level of their upper part, to act as an intermediate lateral reflector for the other conveyor line.
7. Analytical device according to one of the preceding claims, characterized in that it includes associated means of reflection (24-27) arranged so as to intercept the portion of the luminous line adapted so as, after reflection by one of the lateral means of reflection, to illuminate the products directly, so that the optical path of the said portion of the luminous line is of the same order of magnitude as that of the portions of the luminous line projected towards the lateral means of reflection (22, 23) and lower means of reflection (28, 29).
8. Analytical device according to one of the preceding claims, wherein the means of deflection include a polygon (19) provided with facets capable of reflecting the incident beam, and means for driving the said polygon in rotation about an axis of rotation parallel to the direction of progress of the conveyor.
9. Analytical device according to one of the preceding claims, wherein the means of separation consist of a polarizing cube (6, 10, 14).
10. Analytical device according to one of the preceding claims, characterized in that it includes at least two means of illumination (4, 8, 12) and optical means (16-18) capable of mixing the incident beams delivered by the different means of illumination.
11. Analytical device according to claim 10, characterized in that the optical means consist, for each of the means of illumination (4, 8, 12), a blade (16-18) with a selective optical deflection for given wave lengths.

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