System And Method For Detection And Identification Of Foreign Elements In A Substance

Abstract

In one embodiment, a system and method for inspecting a substance to detect and identify predetermined foreign element(s) in the substance. The foreign element may carry X-ray responding material compositions, emitting X-ray signals in response to primary exciting X-ray or Gamma-ray radiation. The inspection is performed during a relative displacement between the substance and an inspection zone, defined by an overlap region between a solid angle of emission of an X-ray/Gamma-ray source and a solid angle of detection of X-ray radiation, along a predetermined movement path, as the substance moves along said path, the detected X-ray radiation includes X-ray response signals from successive portions of the substance propagating towards, through, and out of said overlap region. Measured data indicative of X-ray response signals is analyzed to identify a signal variation pattern over time indicative of a location of at least one foreign element carrying an X-ray responsive marker.

Claims

1. A system for detecting and identifying at least one predetermined foreign element in a substance, the system comprising: a measurement device comprising: a radiation source assembly comprising at least one source of X-ray or Gamma-ray radiation, each source being configured to generate X-ray or Gamma-ray radiation having predetermined properties and a predetermined solid angle of radiation emission to excite a portion of the substance located in a region within said predetermined solid angle to cause an X-ray response of said portion; a detection assembly comprising at least one detector having a solid angle of radiation detection overlapping with said solid angle of radiation emission, each detector being configured and operable to detect an X-ray radiation propagating within a solid angle of radiation detection and generate measured data indicative of the detected X-ray response; the measurement device being configured and operable such that the X-ray radiation being detected during a relative displacement between the substance and at least one of the radiation source assembly and the detection assembly along a movement path is indicative of a time variation of the X-ray response of the substance; and a control unit configured and operable for data communication with said detection assembly to receive and analyze the detection data, the control unit comprising a signal processor configured and operable to identify in said measured data a pattern of a signal variation over time indicative of a location of at least one foreign element carrying an X-ray responsive marker in said substance.

2. The system according to claim 1, wherein said movement path passes through a vicinity of an overlap region between the solid angle of radiation detection and the solid angle of radiation emission.

3. The system according to claim 1, comprising a flow line arrangement comprising a support platform for supporting the substance and moving the substance with respect to the at least one of the radiation source assembly and radiation detection assembly.

4. The system according to any one of claim 1, comprising a flow lines arrangement comprising a translation assembly configured and operable for translating at least one of the radiation source assembly and radiation detection assembly with respect to said movement path.

5. The system according to claim 4, wherein the translation assembly is configured and operable for translating both the radiation source assembly and the detection assembly with respect to the movement path.

6. The system according to claim 5, wherein the translation assembly is configured and operable for simultaneously translating the radiation source assembly and the detection assembly such that their solid angles of emission and detection are oriented towards two opposite lateral sides of the movement path.

7. The system according to claim 1, wherein said source assembly and detection assembly are oriented with respect to the movement path such that said solid angles of radiation emission and detection oppose a direction of movement of the substance along said movement path, such that when the substance moves through the overlap region a distance between the substance and each of the source and detector is being reduced.

8. The system according to claim 7, wherein said pattern of the signal variation over time is characterized by a non-symmetric characteristic signal peak indicative of said location of the at least one foreign element and having a moderate rise of the signal intensity when said distance is being reduced and an sharp intensity fall when said location of said at least one foreign element exits said overlap region, thereby enabling to accurately identify the location of said at least one foreign element along at least one dimension.

9. The system according to claim 8, wherein the signal processor is configured and operable to integrate the measured data indicative of the X-ray response being detected over time while said foreign element is being moved through the overlap region, thereby emphasizing the non-symmetric characteristic of the signal peak.

10. The system according to claim 1, wherein said movement path is a substantially linear path.

11. The system according to any one of claim 1, wherein said movement path has a curvilinear path having at least one curved portion aligned with a boundary of said overlap region.

12. The system according to claim 1, wherein said source assembly and said detection assembly are accommodated at opposite lateral sides of said movement path, thereby yielding reduced variation in detected signal intensity of the X-ray response of a responding foreign element, irrespective of a lateral location of the responding foreign element in a bulk of said substance while in said overlap region.

13. The system according to claim 12, wherein the accommodation is such that the exciting radiation and the X-ray response being detected vary with a distance from the radiation source and radiation detector.

14. The system according to claim 1, wherein the signal processor is configured and operable to identify said at least one foreign element by analyzing the detected X-ray response signal over a database storing X-ray signatures corresponding to multiple known X-ray responsive markers.

15. The system according to claim 1, wherein said at least one foreign element to be identified comprises one or more plastic elements carrying one or more X-ray responsive markers.

16. The system according to claim 15, wherein the signal processor is configured and operable to process said measured data and generate data indicative of quantity of plastic elements within at least a portion of the substance.

17. The system according to claim 1, wherein said radiation source assembly comprises at least two sources of the X-ray or Gamma-ray radiation, each of said at least two sources having the solid angle of emission oriented with respect to the movement path to irradiate a different side surface of the substance, and said detection assembly comprises the at least one X-ray detector with the solid angle of detection oriented to detect the X-ray response signals propagating from a top surface of the substance.

18. The system according to claim 1, wherein the detection assembly comprises at least two detectors whose solid angles of detection are oriented with respect to the movement path to receive the X-ray response signals propagating from two opposite side surfaces of the substance, and the solid angle of emission of said at least one source of the X-ray or Gamma-ray radiation is oriented to irradiate a top surface of the substance.

19. The system of claim 1, wherein the radiation source assembly and the detection assembly are accommodated with respect to the movement path such that the solid angles of emission and detection are oriented towards two different surfaces of the substance.

20. The system of claim 11, wherein said curvilinear movement path is located inside a pipe-band.

21-37. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

[0046] FIG. 1 is a block diagram of the system of the invention for inspecting a substance and detecting and identifying predetermined foreign element(s) in the substance;

[0047] FIGS. 2A and 2B show an exemplary configuration of the system of FIG. 1;

[0048] FIGS. 2C and 2D show two more examples of the configuration of FIG. 1;

[0049] FIG. 3 is a schematic illustration of another example of the configuration of the system of FIG. 1, utilizing a curvilinear movement oath; and

[0050] FIG. 4 is a schematic illustration of yet further example of the configuration of the system of the invention, in which radiation source and detection assemblies are translatable with respect to a movement path.

DETAILED DESCRIPTION OF EMBODIMENTS

[0051] Referring to FIG. 1, there is illustrated, by way of a block diagram, a system 10 configured and operable according to the principles of the invention for inspecting a substance and detecting and identifying predetermined foreign element(s) in the substance. The foreign element to be detected and identified by the system 10 is a so-called “marked” foreign element whose marking(s) has/have characteristic radiation response(s) to predetermined X-Ray or Gamma-ray radiation, which is/are previously determined and stored in a database accessible by the system 10 (via any suitable known communication technique).

[0052] The inspection system 10 includes such main constructional and functional parts as a measurement device 11, and a control unit 16. The measurement device 11 includes a radiation source assembly 12 comprising one or more sources of X-ray or Gamma-ray radiation and a detection assembly 14 comprising one or more detectors configured and operable to detect X-ray radiation. Each i-th radiation source (i=1, . . . n) has a predetermined solid angle of radiation emission RE.sub.i to excite a portion of the substance located in a region within this solid angle RE.sub.i. Similarly, each j-th radiation detector (j=1, . . . m) has a solid angle of radiation detection RD.sub.j.

[0053] It should be understood that a solid angle of radiation propagation is characterized by a general ray propagation direction (being direction from the source and direction towards the detector, respectively) and the angular shape and size (i.e. the shape and size of the field of view of the source and detector, respectively). The solid angle of radiation emission, which defines/determines the volume of the irradiated media/space and its location with respect to the source assembly (i.e. general direction of radiation propagation) is determined by the aperture of the source and possibly also a collimator used in the source. It should be noted that the cross-section of the solid angle may be of any suitable geometry/shape and dimensions, which may or may not be equal along the two perpendicular axis (so-called symmetric or non-symmetrical shape), for example the cross section may be circular, oval-like (e.g. elliptical), or polygonal. The irradiated volume would be of the corresponding shape. Similarly, a volume of space from which a signal can reach the detector is determined by the solid angle of radiation detection, which in turn is determined by an aperture and possibly a collimator used in the detector, and this “readable” volume may be symmetric on non-symmetric in the meaning described above. In this connection, it should also be understood that an actual volume of the region of interest being “read” by the detector is defined by an overlap region between the solid angles of emission and detection within the region of interest, as will be described more specifically further below.

[0054] It should also be understood that if more than one radiation source is used and more than one detector is used, the number of radiation sources may or may not be equal to the number of detectors.

[0055] The configuration of the measurement device 11 (i.e. the orientation of the solid angle(s) of emission and the solid angle(s) of detection) is such that there exists at least one overlap region OR between the solid angles of emission and detection. The overlap region OR actually presents an effective inspection zone. It should also be understood that the source assembly 12 and the detection assembly 14 are appropriately configured to, respectively, generate and be able to detect the X-ray radiation of certain frequencies in accordance with the foreign materials (i.e. markers) to be detected, i.e. radiation capable of exciting certain material compositions to induce X-ray response signals that can be detected by the detection assembly. The detection assembly 14 detects the X-ray response signals and generates measured data MD indicative of said X-ray response.

[0056] The system of the invention is configured such that measurement device 11 performs the inspection session(s) of the substance during a relative displacement between the substance and at least one of the radiation source assembly 12 and the detection assembly 14 along a movement path 22. With this configuration, the X-ray response signals are being detected during the relative displacement along the movement path. More specifically, the relative displacement is between the substance and the overlap region OR between the solid angle of radiation detection RD.sub.j and the solid angle of radiation emission RE.sub.i. The relative displacement provides a movement of a substance (not shown here) in a direction D towards, through and away of the overlap region OR. Thus, the successive regions/portions of the substance successively passing through the overlap region OR are scanned during the movement. As schematically shown in the figure, and will be exemplified and described more specifically further below, the movement path 22 may be a substantially linear path at least in its portion passing through the overlap region, or as shown by dashed curves, the movement path may be a curvilinear path or have a curved portion aligned with a boundary B of the overlap region OR.

[0057] The system 10 may thus be associated with (e.g. may include as its constructional part or may be used with) a flow line arrangement 15, configured to support the substance in a manner allowing its flow with respect to one or more of the radiation source(s) and radiation detector(s), and/or to translate one or more of the radiation source(s) and radiation detector(s) with respect to the substance.

[0058] The control unit 16 is generally a computer device/system having such main functional utilities as data input and output 16A and 16B, memory 16C, and a single processor 18. The control unit 16 is configured and operable for data communication with the detection assembly 14 to receive and analyze the measured data MD.

[0059] It should be understood that, generally, the invention is aimed at detecting the existence of and preferably also location of one or more foreign elements in a substance, in order to “classify” or “sort” the substance as carrying such foreign elements and/or in order to enable removal of the foreign elements from the substance. The foreign elements are of the kind providing X-ray response to primary exciting X-ray or Gamma-ray radiation. Typically, the X-ray response is that generated by specific markers embedded in the foreign elements. The case may be such that detection of the existence of any such “marked” foreign element in the substance is enough to classify or sort the substance; or such that the detection and location of any such “marked” foreign element in the substance is enough; or may be such that identification of the marking and accordingly the foreign element is required or, even more, the detection itself is possible only with respect to identifiable foreign elements.

[0060] Hence, in some embodiments, the signal processor 18 is also configured to (selectively) access a storage device 30 which may be constituted by the internal memory 16C or may be an external storage device accessible via a communication network in which predetermined reference data RD is stored comprising data indicative of various X-ray signatures of various markers in association with respective foreign elements. Generally speaking, each k-th foreign element (k=1, . . . , K) in the database has a number of its associated one or more characteristic X-ray signatures of respective one or more markers. For simplicity, in the non-limiting example of the figure, one of the foreign elements, (Foreign element).sup.(1), has a number g (g=1, . . . G) of its associated characteristic X-ray signatures, (XRS).sub.1.sup.(1) . . . (XRS).sub.G.sup.(1); and another foreign element, (Foreign element).sup.(k), has a number l (l=1, . . . L) of its associated characteristic X-ray signatures, (XRS).sub.1.sup.(1) . . . (XRS).sub.L.sup.(1); where such numbers L and G of the X-ray signatures associated with different foreign elements may be equal or not. The signal processor 18 is configured and operable to identify in the measured data MD a pattern of an X-ray response signal variation over time, which is indicative of a location of at least one foreign element carrying a predetermined X-ray responsive marker.

[0061] More specifically, the signal processor 18 includes an identifier module/utility configured and operable to identify in the measured data, being collected during the movement, the X-ray response signal indicative of the existence of some X-ray responding element in the substance (in case the substance is otherwise not X-ray responding at all) or the X-ray response signal corresponding to the foreign element whose associated reference data is stored in the database. Also preferably provided in the signal processor is a locating module/utility configured and operable to identify the pattern of the X-ray response signal variation over time and determine the location of the respective foreign element. To this end, the control unit 18 may also include a movement controller 32 providing data indicative of a motion pattern of the substance with respect to the overlap region.

[0062] As will be exemplified and described more specifically further below, the system is preferably configured such that the solid angles of radiation emission and detection RE, and ED.sub.j are oriented with respect to the movement path 22 in a manner opposing the direction D of movement of the substance along the movement path 22. With this configuration, when the substance moves towards the overlap region OR, a distance d between the substance and each of the source and detector is being continuously reduced, and starts increasing when the substance moves away from the overlap region. As schematically shown in the figure, this results in that the pattern of the X-ray response signal variation over time, S(t), has a non-symmetric characteristic signal (intensity vs. time) peak SP indicative of the location of the responding marker (responding foreign element). It should be understood that this pattern has a moderate rise of the signal intensity when the distance d is being reduced and a sharp intensity fall when the location of the responding foreign element exits the overlap region OR. This enables accurate identification of the location of the responding foreign element along at least one dimension. As will also be described further below, the signal processor 18 is preferably configured and operable to integrate the measured data (counts) indicative of the X-ray response being detected over time while the substance (and thus the foreign element) is being moved through the overlap region OR, thereby emphasizing the non-symmetric characteristic of the signal peak.

[0063] It should be understood, although not specifically shown, that the flow line arrangement 15 may also include one or more drive units associated with one or more of the substance support platform (e.g. conveyor), the radiation source(s) and the detector(s) for implementing a controllable relative displacement along the movement path.

[0064] The following is the description of some specific but non limiting examples of the configuration/implementation and operation of the above-described system of the invention. In these non limiting examples, the inspection system is described as being used for detecting and identifying plastic contaminants within crops.

[0065] Reference is made to FIGS. 2A and 2B which schematically illustrate an inspection system 100A, which is configured generally similar to the above-described system 10, namely includes: a measurement device including a radiation source assembly (emitter) 102 and a detection assembly (detector) 104; and a control unit 106. The control unit 106 includes input and output utilities 106A and 106B, memory 106C and signal processor 108, and a movement controller 132. The signal processor 108 includes an identification module 108A and a locating module 108B configured and operable as described above. The signal processor is configured as described above to process and analyze measured data MD provided by the detector, by utilizing reference data obtained from a database (e.g. in an external storage device), which is not specifically shown here. FIGS. 2A and 2B show, respectively, the schematic front view and schematic top view of radiation propagation scheme with respect to the movement path. The system 100A is used with a flow line arrangement, which is exemplified here as a continuous track 112 (constituting a substance support platform) defining a movement path.

[0066] Thus, the system 100A includes the radiation source assembly 102 configured for emitting X-ray or Gamma-ray radiation towards a stack or bulk of crop 110 (constituting a substance) moving on a continuous track 112 such as a conveyor belt (constituting a substance' support platform), and the X-ray radiation detector 104 for detecting X-ray response signals, emitted from plastic contaminants that might be contained in the bulk of crop, and generating measured data MD indicative of the detected signals. The signal processor 106, which is in communication with the detector 104, is configured to detect and identify marked plastic contaminants within the bulk of crop. The marked plastic contaminants may be fragments and/or shreds of marked plastic products used during cultivation, harvesting, and processing of the crops. For example, agricultural products such as plastic wraps or nets used for wrapping bales of cotton, hay, or straw, shading nets, mulching films, and various crop packages. Such plastic products, which are likely sources for plastic contamination in crops, are marked by marker(s) comprising one or more markers identifiable according to their characteristic XRF signature (namely, the X-ray response signal to predetermined exciting radiation of each such marker includes one or more unique features corresponding to the marker).

[0067] The marker(s) may be embedded in the plastic products during production by methods such as extrusion, molding, injection, casting and other forming methods. Since the marked plastic products are commonly agricultural products installed in the field, the marker(s) embedded within the product is to be robust and able to withstand harsh weather conditions. Moreover, the marker(s) affect the robustness of the plastic products and their ability to withstand varying environmental conditions, or any of its properties such as strength, elasticity, UV stability, waterproofing capability, appearance, and so on. Additionally, the marker(s) do not negatively affect the plastic products' biodegradability. In an example, the marker(s) is/are embedded within or applied to the plastic product in a concentration of less than 10,000 ppm or less than 5000 ppm. Particular examples of marker(s) for polymers which can be detected and identified by the system of the present invention are described in the above-indicated patent publication WO 2018/069917 assigned to the assignee of the present application.

[0068] Such plastic products may tear and/or disintegrate, forming fragments or shreds by various causes. For example, pieces of products installed in the field, such as shading nets or mulching films, may disintegrate due to UV radiation from the sun, plastic shreds may be created when bale wraps of nets are cut and opened before processing (e.g. wrapped cotton bales in the gin). Plastic fragments and shreds from agricultural products, as well as from local and/or incidental sources, may find their way into the processed crop and may appear throughout the bulk on the continuous track.

[0069] The inspection system 100A is configured to detect and identify plastic fragments located anywhere within the bulk of crop 110 moving on the continuous track 112 (constituting substance' support platform) along the movement path. It should be understood that the continuous track 112 actually presents/defines a movement path resulting from a relative displacement between the bulk of crop 110 and the effective inspection zone (overlap region between the solid angles of emission and detection). As described above, such relative displacement may be achieved by actual movement of either one or more of the emitter 102, detector 104, and substance support platform.

[0070] In order to identify plastic fragments, the radiation source assembly 102 emits exciting X-ray or Gamma-ray radiation towards the bulk of crop 110 on the continuous track 112. Marked plastic fragments, when being irradiated by such exciting radiation (with high enough power and frequency) in region(s)/location(s) of the marker(s) within, or on the plastic, emits X-ray response signals, which pass through the bulk of crop and some distance in air and reach the detector 104. The bulk of crop unavoidably attenuates the response signal passing therethrough. Therefore, in order for the response signal to reach the detector with sufficient intensity to facilitate accurate measurement, it should be of (i) sufficient intensity (i.e. a sufficient number of photons is to be emitted by the markers); and (ii) sufficient energy (i.e. each photon should be of sufficient energy (or frequency)). The higher the energy of the photons, the smaller the absorption of the signal in the crop material (which is an organic, and therefore light material). The radiation source and detector are appropriately configured such that the primary radiation emitted by the emitter is capable of exciting the crop material to cause the response signal from a marker (i.e. the XRF-signature associated with the marker) detectable by the detector. As described above, to this end, the frequency of the exciting radiation is at least as high as the frequency range of the response signal of the particular marker which is to be detected. Preferably, the frequency of the exciting radiation from the emitter assembly is two to three times higher than the expected/searched for response signal of the particular marker. In an example, the XRF-signatures of the one or more markers are of an energy range between 15 KeV and 90 KeV, and consequently the radiation emitted by the emitter assembly is in a range from 30 KeV to 270 KeV. The energy range of the XRF-signatures of the markers may be between 35 KeV and 80 KeV, and consequently the radiation emitted by the emitter assembly is in a range from 70 KeV to 240 KeV. In an example, the markers may be materials with response signals in the above energy ranges. For instance, the markers may include any one or more of the following elements: Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Sb, Te I.

[0071] The attenuation of both the exciting radiation propagating from the emitter assembly to the marker location in the substance (crop bulk) and the response signal propagating from the marker location to the detector depends on the size of a cross section of the substance media (bulk of crop) 110 and its density. Due to attenuation of the signals in the crop which affects the amount of data collected by the detector in unit time, the response signal is to be measured with efficiency, collecting as much data in a time unit as possible. In particular, the measurement mode/scheme is configured to enable detection of signals from marked plastic fragments anywhere within the bulk of crop 110 including plastic fragments which are located on the far end of the bulk relative to the detector 104 and to the emitter assembly 102. It should be noted that in a configuration wherein both the emitter assembly 102 and the detector assembly 104 are positioned on the same side of the movement path (i.e. on the same side of the bulk of crop 110), plastic fragments which are located on the opposite side of the bulk might be difficult to detect, since the exciting radiation from the emitter assembly is attenuated by the relatively long path within the bulk of crop, resulting in a weaker response signal which is further attenuated by the relatively long path to the detector.

[0072] In the exemplary system 100A of the present invention, emitter assembly 102 and detector assembly 104 are positioned on opposite sides of the movement path 112 (on opposite sides of the bulk of crop 110), such that plastic fragments which are located within the crop bulk on the far end of the crop bulk relative to the emitter assembly 102 are not too distant from the detector 104. Also, in this example, the detector 104 is located in a position that slightly deviates from the central ray CRE of the solid angle of radiation emission RE (the center of the emitter's aperture). Hence, as better seen in FIG. 2A, the detector and emitter may be accommodated such that the solid angle of detection is not exactly opposite to the solid angle of emission, but rather the detector's aperture (defining the solid angle) is oriented such that its central axis deviates from the central axis of the emission aperture in order to minimize the amount of primary radiation arriving directly from the emitter assembly 102 to the detector assembly 104.

[0073] The emitter assembly 102 directs X-ray or Gamma-ray radiation towards a section/portion of the bulk of crop 110 (as shown in FIG. 2B). Namely, the primary exciting radiation from the emitter assembly irradiates not the entire cross section of the bulk 110 but only a section/portion thereof which arrives to and passes through the overlap region OR (inspection zone), during the crop bulk movement in the direction D along the movement path (continuous track) 112. The detector 104 receives a sequence of successively generated X-ray response signals from sections/portions of the crop bulk successively passing through the overlap region. The size of the section/portion of the crop bulk being excitable is generally determined by the aperture of the radiation source, and a part of said section/portion of the crop bulk emitting the response signal which is detected by the detector is defined by the intersection of solid angles of emission and detection, i.e. the overlap region OR.

[0074] As described above, the signal processor 106 includes data input utility 106A (which may include an appropriate communication module) for receiving the measured data indicative of the detected X-ray response signals, memory (i.e. non-volatile computer readable medium) 106C for storing database configured as described above for storing preselected data indicative of marking signatures of marked plastic products and of the intensity of the response signal, and the signal processor utility 108 adapted for identifying marked plastic products in the crops and providing indication as to their position on the continuous track. The signal processor utility 108 may further include the identification module 108A adapted for analyzing data collected from the detector 104 and identifying XRF signatures of the various marked products found in the bulk of crop 110, and the locating module 108B adapted for computing and providing indication on the location of plastic fragments in the bulk 110 Based on data provided by the movement controller.

[0075] The emitter assembly 102 and the detector assembly 104 may operate continuously for emitting and detecting radiation. The X-ray response signals (counts and/or counts per second in a plurality of energy ranges) are collected and stored in time bins. That is, counts of the detected signals, corresponding to each of a plurality of energy bands emitted by the substance for a preselected duration of time T.sub.c, as the substance being inspected (e.g. bulk of crop) is displaced with respect to the overlap region along the movement path (e.g. advances on the continuous track 112), are collected, and corresponding measured data is generated and stored in the memory 106C. Signal processor 108 analyzes measured data pieces of the measured data collected in successive time bin, and as the substance (bulk of crop) is being moved (advances on the continuous track), the particular time bin and its corresponding measured data piece is related to a section of a length l=T.sub.c×v, wherein v is the velocity of movement. Signal processor utility 108 is configured to identify the measured data piece corresponding to the time bin and its corresponding section/portion in the substance 110 for the detected X-ray response signals corresponding to the XRF signature(s) of one or more marked foreign elements (plastic products). The signal processor utility 108 may also assess the quantity (in volume or weight) of plastic fragments (either the overall quantity or the quantity of each marked product or type of products) found in each section/portion of the bulk of crop 110. In an example, the inspection system 100A identifies sections/portions of the crop contaminated with marked plastic fragments, distinguishing between biodegradable, bio-based, and ‘regular’ non-degradable or bio-based plastic fragments.

[0076] It should be noted that the signal processor used in the system of the present invention may be adapted for utilizing advanced methods for amplifying, filtering and/or enhancing the detected XRF response signals. For example, such methods are described in the above-indicated patent publication WO 2016/157185 assigned to the assignee of the present application and incorporated herein by reference.

[0077] The locating module 108B is configured and operable as described above to provide an indication on the location of each section/portion of the substance in which fragments of the foreign element(s) were found. In an example, the locating module 108B indicates the location of sections/portions of the substance where the overall quantity of the foreign element(s) is higher than a preselected threshold. In a further example, the locating module 108B indicates the location of every section/portion of the substance in which one or more particular types of foreign elements (e.g. plastic products) are found in quantities higher than a preselected thresholds. Once located, those sections/portions which are heavily contaminated can be removed from the bulk for cleaning, separating the crop from plastic contaminants. In a different example, the inspection system 100A may be used for identifying the sources of the foreign elements, e.g. the sources of plastic contamination, and/or for assessing the quality of the substance (crop).

[0078] Reference is made to FIGS. 2C and 2D two more examples of the configuration and operation of the inspection system of the present invention. For simplicity, in these examples, the same reference numbers are used for identifying components which are common with the examples of FIGS. 2A and 2B.

[0079] In the example of FIG. 2C, an inspection system 100B is shown, which is configured generally similar to the above-described system 10, as well as the exemplary system 100A, namely the system 100B includes: a measurement device including a radiation source assembly (emitter) 102 and a detection assembly (detector) 104; and a control unit 106. The system 100B is used with a flow line arrangement, e.g. a continuous track 112 defining a movement path for the substance movement in a direction D towards the source and detector (towards and through the overlap region OR between the fields of view of the source and detector). The control unit 106 includes input and output utilities 106A and 106B, memory 106C, and signal processor 108, and a movement controller 132. The signal processor 108 includes an identification module 108A and a locating module 108B configured and operable as described above. The signal processor is configured as described above to process and analyze measured data MD provided by the detector, by utilizing reference data obtained from a database (e.g. in an external storage device), which is not specifically shown here. The system 100B is different from the previously described exemplary system 100A in that in the system 100B the configuration is such that the central axis of the solid angle of radiation detection RD is substantially perpendicular to a plane of the movement path, or in other words, the detector “looks” onto the top of surface of the substance, e.g. is positioned above the bulk of crop as it moves on a continuous track emitting radiation towards the top surface of the bulk of crop. As for the emitter assembly 102, the solid angle of radiation emission is directed towards one of the lateral sides of the movement path, to face one of the side surfaces of the substance (bulk).

[0080] In the example of FIG. 2D, an inspection system 100C is shown, which is different from the above described exemplary systems 100A and 100B in that the radiation source assembly 102 includes two emitter units associated with a single detector of the detection assembly 104. The emitter units 102A and 102B and oriented with respect to the movement path such that primary exciting radiation components of X-ray or Gamma-ray radiation emitted by the emitter units 102A and 102B are directed towards two opposite lateral sides of the movement path to irradiate two opposite surfaces of the substance (bulk of crop) being displaced along the movement path (on the continuous track) in a general movement direction D towards and through the overlap region OR between the fields of view of the sources and detector. Detector 104 is oriented with respect to the movement path similar to the above-described example of system 100B, i.e. the central axis of the solid angle of radiation detection RD is substantially perpendicular to a plane of the movement path, or in other words, the detector “looks” onto the top of surface of the substance, e.g. is positioned above the top surface of the bulk of crop. The radiation propagation channels for the primary radiation components emitted by the two emitters and for the X-ray response signals propagating to the detector overlap in the overlap region OR. The overall radiation emitted by the two emitter assemblies 102A and 102B may by of higher power (that is, emit more photons). Furthermore, as the two emitter assemblies 102A and 102B are located on opposite sides of the bulk, the radiation arriving at the bulk is more homogenous throughout the cross section of the bulk than in other configurations with single emitter assembly.

[0081] Reference is now made to FIG. 3 which is a schematic illustration of an exemplary inspection system 200 of the present invention, configured generally similar to the above described/exemplified systems, but in which the movement path 212 is a curvilinear path, namely has (at least) one curved portion 212′ aligned with the boundary of the overlap region OR. Thus, the inspection system 200 includes: a measurement device including a radiation source assembly (emitter) 102 and a detection assembly (detector) 104; and a control unit 206. The measurement is configured for inspecting a substance during movement (flow) along the movement path in a general movement direction D towards and through the overlap region OR between the fields of view of the source and detector assemblies, where the overlap region is aligned with the curved region/portion. The control unit 206 includes input and output utilities 206A and 206B, memory 206C, and signal processor 208, and a movement controller 232. The signal processor 208 includes an identification module 208A and a locating module 208B configured and operable as described above. The signal processor is configured as described above to process and analyze measured data MD provided by the detector, by utilizing reference data obtained from a database (e.g. in an external storage device), which is not specifically shown here.

[0082] The system 200 may be used for identifying plastic contaminants within a load of crop as it moves inside the pipe towards, though and our of the overlap region OR. The emitter assembly 202 is configured for emitting X-ray or Gamma-ray radiation towards the substance (crop) moving inside the pipe 210. The substance may contain foreign element (plastic contaminants as fragments or shreds). The detector 204 detects X-ray response signals emitted from the markers in the foreign elements in response to excitation by said exciting radiation. The signal processor 206 is in communication with the detector 204 and is configured to detect and identify marked foreign elements in the successive portions of the substance moving through the pipe 210 (plastic contaminants within crop in the pipe). As described above, the signal processor 206 utilizes predetermined reference data in a database which may be stored in the memory 206C or external storage device, configured generally similar to that described above with reference to FIG. 1, where the reference data includes various marking signatures of marked foreign elements (plastic products) and the intensity of the response signal. The signal processor utility 208 may be configured and operable for identifying fragments of marked plastic products in the crop; and providing indication as to their position in the pipe. Data processing utility 208 may further include the identification module 208A adapted for analyzing data collected from the detector 204 and identifying XRF signatures of the various marked products found in the crop; and locating module 208B adapted for computing and providing indication on the location of plastic fragments in the crop.

[0083] In an embodiment of the present invention, the system 200 makes use of a pipe bend (curved region/portion) in order to improve the efficiency and accuracy of the measurements (detection and location) of marked foreign elements (plastic contaminants). The emitter assembly 202 and detector 204 are both positioned in the vicinity of the curved portion of the movement path (the pipe bend) with their apertures (solid angles of radiation emission and detection) facing the direction of substance movement along the movement path (facing the incoming crop), such that the emitter assembly 202 directs primary exciting X-ray or Gamma-ray radiation inside the pipe towards the substance (in a direction opposite to the movement direction of the substance), and the detector 204 detects the backscattered radiation (i.e. the X-ray response signal from the marked locations in the substance) propagating in the direction of the movement of the substance.

[0084] Such a system configuration exemplified in FIG. 3 (i.e. with the curvilinear movement path, formed by a relative displacement between the substance and the effective inspection zone defined by the overlap region) has a number of advantageous. As the substance (e.g. crop) flows towards the overlap region (towards the emitter 202 and the detector 204) measured data (counts of the detected X-ray response signals) is being generated during a time period from the point where the responsive foreign elements (markers) are close enough for the response signal to reach the detector 204 and up to the curved region of the movement path (pipe band) where the detector 204 is positioned. Consequently, more data may be collected enhancing the accuracy of the measurement. Additionally, since the solid angles of the emission and detection of the emitter 202 and the detector 204, respectively, face (are directed towards) the cross section of the pipe and the crop load is advancing towards it, all the marked elements pass at the vicinity of the detector 204 (preventing a situation wherein foreign elements within the crop remain distant from the detector), reducing the probability of a marked element passing undetected. Furthermore, the intensity of the signal coming from the marked fragments increases as the fragments flow towards the detector 204 with a maximum at the point where the fragment is closest to the detector 204 at the point where the flow of the crop changes the flow direction. As shown in FIG. 3, the pipe band may change the direction of the flow substantially perpendicularly, causing the crop and the marked fragments to exit the region/volume which is radiated by the emitter and/or the volume from which response signals may reach the detector. The intensity of the detectable response signal increases gradually as the marked fragment moves towards the detector 204 (depending on the velocity of flow of the crop) and drops much faster once the fragment reaches the closest point to the detector and then abruptly exits the volume irradiated by the emitter or the volume ‘seen’ by the detector. If the counts measured by the detector are collected in small enough time bins (e.g. fractions of a second), then the sudden decrease in the intensity of the response signal indicates with high accuracy the location of a section of the crop in the pipe where one or more marked fragments exist.

[0085] Placing the emitter assembly 202 and detector 204 within the pipe or attached to the pipe wall (such that radiation from the emitter assembly and response signals from the crop are emitted within the pipe) might be advantageous as this may require less shielding for blocking scattered radiation from reaching the vicinity of the system 200.

[0086] Reference is now made to FIG. 4 which is a schematic illustration of yet another embodiment of the invention. As inspection system 300 shown in the figure is generally similar to any of the above-described and exemplified system configurations, namely includes: a measurement device including a radiation source assembly (emitter) 302 and a detection assembly (detector) 304; and a control unit 306. The control unit 306 includes input and output utilities 306A and 306B, memory 306C, and signal processor 308, and a movement controller 332. The signal processor 308 includes an identification module 308A and a locating module 308B configured and operable as described above. The signal processor is configured as described above to process and analyze measured data provided by the detector, by utilizing reference data obtained from a database (e.g. in an external storage device), which is not specifically shown here. The system 300 may be used for identifying plastic contaminants within a bale of crop 310. The emitter assembly 302 is configured for emitting primary X-ray or Gamma-ray radiation towards a bale of crop 310; the bale of crop may contain plastic contaminants as fragments or shreds; and the detector 304 is configured for detecting X-ray response signals emitted from the plastic contaminants.

[0087] In this example, a flow line arrangement is provided including a translation assembly 320 comprising appropriate driver mechanism(s) (not shown here) operated by the movement controller 332 for controllably moving the emitter assembly 302 and/or the detector assembly 304, or preferably moving both of them, relative to the substance 310 (bale of crop). The source and/or detector is/are preferably moved in the direction D along an axis parallel to the movement path 112, thus scanning the substance.

[0088] The bale of crop 310 may be a bale of harvested crop before processing (for example a bale of cotton before it is processed in a cotton gin) or a bale of crop after processing, for example a bale of compressed cotton after processing in the gin). The bale 310 may be commonly stationary, while the emitter assembly 302 together with the detector assembly 304 move relative to the bale of crop 310 scanning the bale. The emitter assembly 302 may move along one or more axes parallel to at least one lateral side of the movement path, i.e. to at least one surface of the bale, while emitting the primary X-ray or Gamma-ray radiation towards the bale 310, and the detector 304 may move along the parallel axis (on the opposite side of the movement path) along one or more surfaces of the bale 310 simultaneously with the emitter assembly' movement, thus detecting the response signals emitted from the marked plastic fragments within the bale 310. In order to minimize the amount of (primary) radiation arriving directly from the emitter assembly 302 to the detector 304, the detector 304 is not positioned exactly opposite the emitter assembly 302 (on the axis defined by the direction of the beam of radiation emitted by the emitter assembly 302), but is slightly spaced from the axis and its aperture is directed to a slightly different axis.

[0089] In some embodiments, the emitter assembly 302 and the detector 304 are configured to continuously emit and detect radiation, respectively, while scanning the bale. Data collected by the detector 304 is stored in memory 308B and processed by the signal processor 306. The signal processor utility 308 operates to identify in the measured data the X-ray response signals corresponding to XRF signatures of one or more marked plastic products indicating the presence and possibly the source of plastic contamination within the bale 310. The measured data collected by the detection assembly 304 may be collected for the duration of a preselected time period or a sequence of time periods (time bins) corresponding to successively scanned sections of the bale or alternatively for the entire duration of the scanning of the bale (corresponding to the bale). Therefore, in an example the system 300 may be configured to provide indication on the quantity of marked plastic contaminants in each section of bales. In a different example, the system 300 is configured to provide indication on the quantity of marked plastic contaminants in the entire bale. In an aspect of the system 300 may provide indication as to types of plastic fragments and their possible sources (that is the plastic product from which they originate) in the bale or possibly in each section of the bale.

[0090] Thus, the present invention provides a novel approach for inspecting a substance to detect and identify (and preferably also locate) foreign element(s) in the substance during a relative displacement between the substance and one or more elements of the inspection system. The principles of the invention are not limited to any specific type of substance, as well as not limited to any specific foreign element, provided the foreign element is of the type carrying an X-ray responding material(s).