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EP-4739445-A1 - OPTICAL SORTING APPARATUS WITH MULTIPLE LIGHT BEAMS AND ACCORDING METHOD

EP4739445A1EP 4739445 A1EP4739445 A1EP 4739445A1EP-4739445-A1

Abstract

Sorting apparatus and method for detecting irregular products (7) in a product flow, wherein at least two light beams (8,9) are made to strike a rotating polygon mirror (12) such that said light beams (8,9) are directed towards the product flow in a detection zone (4) wherein the light beams (8,9) are each made to strike a different plane of the polygon mirror (12) so as to direct the light beams (8,9) to different parts (21,22) of said detection zone (4) and move them over said parts (21,22).

Inventors

  • BERGHMANS, PAUL
  • HOUTMEYERS, Tom
  • de Jonghe, Jan
  • Beyens, Patrick
  • GOVAERTS, Daan

Assignees

  • Optimum N.V.

Dates

Publication Date
20260513
Application Date
20240708

Claims (17)

  1. 1. Sorting apparatus for detecting irregular products (7) in a product flow moving through a detection zone (4) in a direction of travel, having a detection device (5) comprising one or several detectors (17,27) and equipped with at least one beam source (10,11) for generating at least two light beams (8,9), a polygon mirror (12) being provided which is rotatably mounted with respect to a scan axis (13) for directing said light beams (8,9) to the detection zone (4) via a corresponding optical path and for moving said light beams (8,9) over the detection zone (4) in a scanning direction (8a, 9a) extending practically transversely to said direction of travel so that the light beams (8,9) are incident on said product flow in the detection zone (4) and are reflected by products (1) from said product flow onto which they strike, generating reflected light beams (15,16) which are directed at least partly through said polygon mirror (12) to said detectors (17,27) in order to generate detection signals, a control unit being provided for sorting said products (I) on the basis of these detection signals, characterised in that said light beams (8,9) each strike a different plane of said polygon mirror (12) so that the light beams (8,9) are directed towards different parts (21,22) of said detection zone (4).
  2. 2. Sorting apparatus according to claim 1, wherein said different parts (21,22) of the detection zone partially overlap.
  3. 3. Sorting apparatus according to claim 1 or 2, wherein said light beams (8,9) strike the polygon mirror (12) on opposite sides of a plane extending transversely to said detection zone (4) and comprising said scan axis (13).
  4. 4. Sorting apparatus according to any one of claims 1 to 3, comprising a first beam source (10) which makes a first light beam (8) strike said polygon mirror (12) in order to direct this light beam (8) to a first part (21) of said detection zone (4), wherein this first beam source (10) cooperates with at least one detector (17) specifically provided for this purpose, whereas a second beam source (I I) is further provided which makes a second light beam (9) strike said polygon mirror (12) in order to direct this light beam (9) to a second part (22) of said detection zone (4), wherein this second beam source (11) also cooperates with at least one detector (27) specifically provided for this purpose.
  5. 5. Sorting apparatus according to any one of claims 1 to 4, wherein said detection zone (4) extends practically parallel to the product flow and practically transversely to the direction of travel of the latter.
  6. 6. Sorting apparatus according to any one of claims 1 to 5, wherein said detection device (5) comprises a mounting plate (24) having a surface on which at least said polygon mirror (12) and said detectors (17,27) are mounted, said scan axis (13) forming an angle (a) with respect to this surface of the mounting plate which is smaller than 90°.
  7. 7. Sorting apparatus according to any one of claims 1 to 5, wherein said detection device (5) comprises a mounting plate (24) on which at least said polygon mirror (12) and said detectors (17,27) are mounted, wherein a detection surface (25) is defined by the straight part of the optical path of the part of the reflected stream of light (15,16) striking said detectors (17,27) downstream of said polygon mirror (12) and by the path of the light beam (8,9) emanating from said beam source (10,11) and striking the polygon mirror, wherein said scan axis (13) forms an angle (a) with respect to the detection surface (25) which is smaller than 90°.
  8. 8. Sorting apparatus according to claim 6 or 7, wherein said angle (a) is between 25° and 50° and in particular in the order of magnitude of 35°.
  9. 9. Sorting apparatus according to any one of claims 6 to 8, wherein said mounting plate (24) forms an angle (P) with a horizontal plane between 30° and 80° and in particular in the order of magnitude of 45°.
  10. 10. Sorting apparatus according to any one of claims 1 to 9, wherein a fixed aiming mirror (28,29) is provided for each of said light beams (8,9), placed in said optical path between the polygon mirror (12) and the detection zone (4) so that each light beam (8,9) is directed from the polygon mirror (12) to the detection zone (4) via the corresponding aiming mirror (28,29). 11. Sorting apparatus according to claim 10, wherein a plane which is parallel to said scan axis (13) and which extends in the direction of the part of the optical path of the light beams (8,9) emanating from said beam source (10,
  11. 11) which strike the polygon mirror (12), extends between said detection zone (4) and said aiming mirrors (28,29).
  12. 12. Sorting apparatus according to any one of claims 1 to 11, wherein said control unit cooperates with a removal device (18) to remove irregular products (7) from the product flow.
  13. 13. Sorting apparatus according to any one of claims 1 to 12, wherein said polygon mirror (12) has consecutive adjacent mirrors, preferably flat, extending along the circumference of the polygon mirror and parallel to said scanning axis.
  14. 14. Method for detecting irregular products (7) in a product flow, wherein said product flow is moved in a direction of travel through a detection zone (4), wherein at least two light beams (8,9) are made to strike a rotating polygon mirror (12) driven about a scan axis (13), so that said light beams (8,9) are directed to the detection zone (4) via a corresponding optical path and are moved over the detection zone (4) in a scanning direction (8a, 9a) extending practically transversely to said direction of travel, so that the light beams (8,9) in the detection zone (4) are incident on said product flow and are reflected by products (1) from this product flow onto which they strike, wherein these reflected light beams (15, 16) are directed at least partly via said polygon mirror (12) to detectors (17,27) of a detection device (5) for generating detection signals, wherein said products (1) are sorted on the basis of these detection signals, characterised in that said light beams (8,9) are each made to strike a different plane of said polygon mirror (12) in order to direct the light beams (8,9) to different parts (21,22) of said detection zone (4) and to move them over these parts (21,22).
  15. 15. Method according to claim 14, wherein said parts (21,22) of the detection zone (4) are selected such that they partially overlap and together cover the entire detection zone (4).
  16. 16. Method according to claim 14 or 15, wherein said light beams (8,9) are made to strike the polygon mirror (12) on opposite sides of a plane extending transversely to said detection zone (4) and comprising said scan axis (13).
  17. 17. Method according to any one of claims 14 to 16, wherein said first beam source (10) is provided to make a first light beam (8) strike said polygon mirror (12) so as to direct this light beam (8) to a first part (21) of said detection zone (4), wherein said first light beam (8) is made to strike at least one detector (17) which is specifically provided for this first light beam (8) after it has been reflected by said products (1), while a second beam source (11) is further provided to make a second light beam (9) strike said polygon mirror (12) in order to direct this light beam (9) to a second part (22) of said detection zone (4), wherein this second light beam (9) is made to strike at least one detector (27) which is specifically provided for this first light beam (9) after it has been reflected by said products (1).

Description

OPTICAL SORTING APPARATUS WITH MULTIPLE LIGHT BEAMS AND ACCORDING METHOD The invention concerns an optical sorting apparatus for detecting irregular products in a product flow moving through a detection zone in a direction of travel. This sorting apparatus has a detection device with one or several detectors and is equipped with at least one beam source to generate at least two light beams. Furthermore, a polygon mirror is provided which is rotatably mounted in relation to a scan axis to direct said light beams towards the detection zone via a corresponding optical path and move them across said zone in a scanning direction. The scanning direction extends practically transversely to the direction of travel of the product flow, so that the light beams in the detection zone are incident on said product flow and are reflected by products from said product flow. Thus, the light beams are reflected and directed at least partially, via said polygon mirror, to the detectors in order to generate detection signals. A control unit is provided to classify and/or sort the products from the product flow based on these detection signals. In such a sorting apparatus, the width of the detection zone and therefore of the product flow is relatively limited to allow accurate detection of irregularities. Indeed, as the width of the detection zone increases, said light beams at the far ends of the detection zone will strike the mirror surface of the polygon mirror and the product flow at a smaller angle. This small angle, and the large distance that the light beam has to travel over the detection zone, increase the margin of error for detecting irregularities in the product flow and make this detection insufficiently accurate. According to the present state of the art, this problem is solved by using multiple detection devices, each with its own light source and polygon mirror. Each polygon mirror ensures that an associated light beam covers part of the detection zone. Such an arrangement is presented for example in Figure 9 of document US 2014/0362382 Al, but it has the major disadvantage that the movement of the different light beams must be synchronised in order to avoid their simultaneous incidence in the same place of the product flow, which would generate an erroneous detection signal. In addition, such a sorting apparatus with multiple polygon mirrors and a synchronisation system is relatively complex and not very compact. The invention aims to remedy these disadvantages and present a sorting apparatus that does not have these disadvantages and yet allows a relatively wide product flow to be scanned over a wide detection zone in order to detect irregular products. Thus, the invention aims to make it possible to develop a sorting apparatus that allows a product flow to be sorted at a higher flow rate and with more accuracy than is the case with existing sorting apparatuses. To this end, said light beams are each incident on a different plane of said polygon mirror, as a result of which the light beams are directed towards different parts of said detection zone. Practically, said different parts of the detection zone partially overlap. Advantageously, said light beams are incident on the polygon mirror on opposite sides of a plane comprising said scan axis and which is transverse to said detection zone. In an interesting manner, the sorting apparatus according to the invention comprises a first beam source which makes a first beam of light strike said polygon mirror in order to direct said light beam to a first part of said detection zone. Said first beam source thereby cooperates with at least one detector provided specifically for this purpose. Furthermore, a second beam source is provided which causes a second light beam to strike the polygon mirror in order to direct this light beam to a second part of the detection zone. This second beam source also cooperates with at least one detector provided specifically for this purpose. According to an interesting embodiment of the sorting apparatus according to the invention, the detection device comprises a mounting plate on which at least the polygon mirror and said detectors are mounted. This mounting plate is parallel to a detection surface, the scan axis having an angle with respect to this detection plane and/or with respect to the mounting plate that is less than 90°. The detection surface is defined, for example, by the part of the optical path of the part of the reflected light beam that is incident on said detector downstream of the polygon mirror and by the part of the optical path of the light beam, connecting to the polygon mirror, emanating from said beam source which is incident on the polygon mirror. According to a preferred embodiment of the sorting apparatus according to the invention, the detection surface forms an angle with a horizontal plane that is between 30° and 80° and in particular is of the order of magnitude of 45°. According to a particular em