Abstract:
An apparatus and method for selectively removing or sorting undesirable articles wherein a product stream is transported by a conveyor, and then interrogated by an optical scanner and sorting processor to inspect and label the articles according to user specified criteria. Articles labeled or classified as undesirable articles are removed by an ejector or removal station while desirable or acceptable articles are passed.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to provisional application No. 60/926,246, filed on Apr. 25, 2007, the disclosures of which are incorporated herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Methods and machines for sorting articles have been known in the art for many years and are useful for separating desirable and undesirable articles from a product stream using a variety of methods. The machines found in the art include types that utilize reflecting electromagnetic radiation in the form of light to determine the optical reflective characteristics of the articles in the product stream using color as a determinant. A notable example of such a sorter is the High Speed Mass Flow Sorting Apparatus for Optically Inspection and Sorting Bulk Food Products as shown in U.S. Pat. No. 5,887,073 assigned to Key Technology, Inc. Another notable example of an exemplary sorter is shown in copending patent application Ser. No. 11/392,947 filed on Mar. 30, 2006 the disclosures of which are incorporated by reference herein. 
     Some methods and machines for sorting articles utilize emitted light from articles to be sorted in an effort to make a determination between desirable and undesirable articles. Often, it is desirable for a sorting apparatus to include an ability to distinguish between organic and inorganic articles. It is known in the art that chlorophyll produces a fluorescence emission in response to an excitation wavelength. Chlorophyll is an essential molecule during photosynthesis and is present in varying forms in many plants, including many comestible articles such as green beans and peas. 
     An example of a machine or method that exploits this property is disclosed in U.S. Pat. No. 6,734,383. Here, light is cast onto articles in a product stream and a passed in front of a fluorescent or backlit background element. In this example, the emission from the background is selected to be within an order of magnitude of the emission of the desirable articles which are presumed to emit light due to their chlorophyll response. This approach provides a clear distinction between desirable articles that emit light and undesirable non-emitting articles, effectively reducing a sorting decision to a basic thresholding operation. 
     This approach, while simple, suffers from a number of shortcomings. One specific shortcoming that limits the widespread application of this machine or method is the fact that different types of articles, varieties of articles, and even the manner in which the articles are prepared can have a profound impact on the magnitude of the light that is emitted by fluorescence from the articles. This reality requires that the background element be carefully selected or tuned for a specific application. In a typical food processing line, it is common that multiple types of articles, varieties of articles, and methods of treatment of the articles are utilized over the course of operation to satisfy both the supply and market needs. This situation requires that the machine operator have at their disposal an appropriate background element for each situation. In addition, this presents an additional burden on the manufacturer of the machine to design and produce a family of background elements, each tuned to a specific situation. 
     The present invention overcomes this and other limitations of the prior art, and is equipped with a background element that does not fluoresce or emit light. The invention utilizes an expanded capability of gathering and manipulating light emitted and returned by articles in a product stream, and light returned by a passive background element. This expanded capability is realized by devoting one channel of an optical scanner to measuring light emitted from articles, another channel for measuring reflected light from the articles and background element, and another channel for measuring light that is reflected and scattered to some degree by the articles and the background element. A sorting processor receives the measurements from these channels and logically combines them with previously defined and user identified criteria to make a determination whether or not an article is an acceptable or unacceptable article. 
     SUMMARY OF THE INVENTION 
     One aspect of the invention is a sorting apparatus for selectively removing undesirable articles from a product stream, including a conveyor positioned in transporting relation to the product stream, and a removal station positioned proximate to the product stream. The invention also includes a background element positioned proximate to the product stream, and an optical scanner configured to project electromagnetic radiation having a preponderance of energy at a first wavelength onto the product stream and the background element. In addition, the invention includes a first sensor configured to convert light or electromagnetic radiation returned from articles in the product stream having a wavelength that is longer than the first wavelength into a first signal, a second sensor configured to convert light or electromagnetic radiation having the first wavelength that is reflected by articles in the product stream and from the background element into a second signal, a third sensor configured to convert light or electromagnetic radiation having the first wavelength that is scattered by articles in the product stream and from the background element into a third signal, a sorting processor connected to the removal assembly and operable to receive the first, second, and third signals, and a user interface connected in data communication to the sorting processor. 
     Another aspect of the invention includes a sorting apparatus for selectively removing undesirable articles from a product stream, having a conveyor positioned in transporting relation to the product stream, a removal station positioned proximate to the product stream, a background element positioned proximate to the product stream, and a scanning assembly configured to project light or electromagnetic radiation onto the product stream and the background element, and further configured to receive light or electromagnetic radiation that is reflected by the background element, and to receive light or electromagnetic radiation that is reflected and/or emitted by articles in the product stream, and wherein the scanning assembly is configured to emit light or electromagnetic energy having a preponderance of energy at a first wavelength. In the invention, the scanning assembly further includes a first channel configured to measure light or electromagnetic radiation returned from articles in the product stream having a wavelength that is longer than the first wavelength, a second channel configured to measure light or electromagnetic radiation reflected by articles in the product stream and from the background, and a third channel configured to measure light or electromagnetic radiation that is scattered by articles in the product stream and from the background. The invention also includes a sorting processor connected to the scanning assembly and removal assembly, and operable to receive data from the scanning assembly, and operable to provide a virtual image of the articles wherein colors are assigned to each of the first, second, and third channels of the scanning assembly, and wherein the sorting processor is further operable to compare this data with user defined sorting criteria operable to classify articles in the product stream as either undesirable articles or acceptable articles, and further operable to transform the classification of articles into specific sequenced commands that control the removal station to selectively remove undesirable articles from the product stream. 
     Yet another aspect of the invention includes a sorting method for selectively removing undesirable articles from a product stream, which includes providing an optical scanner, a sorting processor in signal communication with the optical scanner, and a passive background element positioned proximate to the product stream. The invention further includes projecting electromagnetic radiation from the optical scanner having a preponderance of energy at a first wavelength onto the product stream and the background element, and converting light or electromagnetic radiation returned from articles in the product stream having a wavelength that is longer than the first wavelength into a first signal by the optical scanner, and converting light or electromagnetic radiation having the first wavelength that is reflected by articles in the product stream and from the background element into a second signal by the optical scanner, and then converting light or electromagnetic radiation having the first wavelength that is scattered by articles in the product stream and from the background element into a third signal by the optical scanner; and transforming each of the first, second, and third signals into a first, second, and third data stream that is representative of the time varying magnitude of each of the signals in the sorting processor. 
     These and other aspects of the present invention will be described in greater detail hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the invention are described below with reference to the following accompanying drawings. 
         FIG. 1  is a block schematic diagram of the sorting apparatus having the features of the present invention. 
         FIG. 2  is a block schematic diagram of the scanning assembly and sorting processor in relation to the background element and the product stream. 
         FIG. 3  is a simplified pictorial diagram of the user interface utilized in one aspect of the invention. 
         FIG. 4  is a time-chart representation of the magnitude of selected signals and data streams that are generated by the scanning assembly in response to light or electromagnetic radiation that is emitted, reflected, and scattered by articles in a product stream and a background element. 
         FIG. 5  is a time-chart representation of the magnitude of selected signals and data streams that are generated by the scanning assembly in response to light or electromagnetic radiation that is emitted, reflected, and scattered by articles in a product stream and a background element. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8). 
     Referring now to  FIG. 1 , an apparatus for sorting articles is shown and is generally identified by the numeral  10 . The apparatus is shown in receiving relation to a stream of articles designated as the product stream  12 . In practice, for example, the product stream  12  may include comestible items such as vegetables. Yet further the product stream  12  may include other non-organic articles such as glass fragments or wood. The product stream  12  is composed of individual articles traveling in a direction generally depicted by the flow arrow  14 . The product stream  12  may include individual articles that are moving in concert at a generally uniform speed and traveling in the product flow direction  14 . The individual articles often vary parametrically in dimension, density, color, etc. Often, the quality of an article in a product stream may be ascertained, and may be divided into acceptable articles  16  and undesirable articles  18 . 
     Articles in the product stream  12  are transferred to a conveyor  20  for transport through the apparatus for classifying and sorting articles  10 . The conveyor  20  includes an endless belt  22  selected to provide a carrying surface for articles in the product stream  12 . The endless belt  22  has a texture which is selected to provide a coefficient of friction useful for stabilizing articles in the product stream  12  as they are transported in the flow direction  14 . 
     The sorting apparatus  10 , has a user interface  24  that enables an operator (not shown) to observe and control various operational aspects of the sorting apparatus  10  as will be discussed in further detail below. The user interface  24  may include a CRT or LCD panel for output display. For input, the user interface  24  may include a keyboard, touch-screen or other input means known in the art. The operator can view representations of the articles in the product stream  12  as they are processed in the sorting apparatus  10  on the user interface  24 . Yet further, the user interface  24  provides a means for the operator to configure the operation of the sorting apparatus  10  to make a determination between an acceptable article  16  and an undesirable article  18 . Data gathered by the user interface  24  and provided to the user interface are transported as user interface data  25 . 
     Articles in the product stream  12  are transported along a path to the end of the conveyor  20  where they are launched in a trajectory through a region of sight  26 . The region of sight  26  extends along in transverse relation to the conveyor  20 , and has a length that is slightly less than the width of the conveyor  20 . 
     A removal station or ejector manifold  28  is positioned in downstream relation to the region of sight  26 , and in fluid transmission relation to the trajectory of the product stream  12 . The ejector manifold  28  includes a plurality of ejector nozzles  30  which are individually directed and controlled to selectively remove undesirable articles  18  from the product stream  12 . The ejector nozzles  30  act as conduits for directing fluid pulses to dislodge or otherwise re-direct articles traveling in the trajectory. Individual ejector valves contained in the ejector manifold  28  are driven by a plurality of removal signals  29  whose origination and operation will be discussed in further detail below. 
     Articles that are selectively dislodged from the product stream  12  are guided to a reject conveyor  32  useful for collecting and transporting articles from the product stream  12 . In desired operation, the sorting apparatus  10  will direct a high percentage of undesirable articles  18  from the product stream  12  to the reject conveyor  32 . However, actual experience has shown that a minority of acceptable articles  16  may also be dislodged by the ejector nozzles  30  and be collected and transported by the reject conveyor  32 . In practice, the reject conveyor  32  may be a belt conveyor, vibratory conveyor, chute, flume, or other suitable transport device or arrangement known in the art. 
     Articles from the product stream  12  that are allowed to proceed in their natural trajectory in the absence of disturbances from the fluid pulses provided by the ejector nozzles  30  travel and are collected and transported by an accept conveyor  34 . In desired operation, the sorting apparatus  10  will direct a high percentage of acceptable articles  16  from the product stream  12  to the accept conveyor  34 . However, actual experience has shown that a minority of undesirable articles  18  may not be dislodged by the ejector nozzles  30 , and hence, be collected and transported by the accept conveyor  34 . In practice, the accept conveyor  34  may be a belt conveyor, vibratory conveyor, chute, flume, or other suitable transport device or arrangement known in the art. 
     Referring still to  FIG. 1 , a scanning assembly  36  is positioned in light transmission relation to the region of sight  26 . A beam of light  40  or other form of electromagnetic radiation is emitted by the scanning assembly  36  and directed by a path folding mirror  38  through the region of sight  26 . Often, a portion of light from the beam of light  40  that is reflected or refracted by articles in the product stream  12  is directed along a coincident return path back to the scanning assembly  36 . 
     At other times, a the beam of light  40  proceeds in unimpeded fashion through the region of sight  26  and travels to a background element  42 . The background element  42  is composed of a material which reflects, diffuses and refracts light but does not otherwise emit light or electromagnetic radiation. In one embodiment, the background element  42  is composed of an acetal resin having the Delrin registered trademark of the DuPont Corporation. Other materials known by those skilled in the art which suitably reflect, diffuse, and refract light and does not otherwise emit light may be substituted without departing from the scope of this invention. A portion of the beam of light  40  that is refracted or reflected by the background element  42  proceeds along a coincident return path back to the scanning assembly  36 . 
     The scanning assembly  36  provides a plurality of scanning signals  44  that are time sequenced representations of various aspects of the portion of the returned beam of light  40  or other wavelengths of electromagnetic radiation. These aspects of the scanning signals  44  will be discussed in more details below. 
     A sorting processor  46  is connected in signal and data relation to the user interface  24 , the scanning assembly  36 , and the ejector manifold  28 . The sorting processor  46  is operable to provide real-time command and control of the apparatus  10  in response to the scanning signals  44  and configuration and command information provided by the operator (not shown) via the user interface  24  or other suitable interface means known in the art. The sorting processor  46  provides the plurality of removal signals  29  in response to a plurality of comparative functions operable to classify articles in the product stream  12  as acceptable articles  16  or undesirable articles  18 . The sorting process  46  accomplishes this task by gleaning information from the scanning signals  44  and configuration data provided by the user in the form of user interface data  25 . The operation of the sorting processor  46  will be discussed in further detail below. 
     Referring now to  FIG. 2 , the scanning assembly  36  emits a beam of light or other wavelength of electromagnetic radiation that originates from a light source  60 . In one embodiment of the invention, the light source  60  is a laser having a central emitting wavelength of approximately 660 nm. The light source  60  preferably includes one or more lasers which are operable to direct a concentrated source beam  62  having a relatively small cross-sectional area. 
     The source beam  62  interacts with and is reflected by a mirror  64  positioned in reflecting relation to the source beam  62 . The source beam  62 , after being reflected by the mirror  64 , travels through an aperture formed in a splitter mirror  66  which is operable to pass light or other wavelengths of electromagnetic radiation through an aperture formed therein while simultaneously reflecting light or electromagnetic radiation traveling from an opposite direction. Light or electromagnetic radiation that has passed through the splitter mirror  66  interacts with a scanning mirror  68 . The scanning mirror  68  may be polygonal in nature, having a number of sides, with the number of sides preferably equal to twelve. The geometry of the scanning mirror  68  is specified to provide a scanning line over a specified distance at a rate that is partially determined by the speed of a motor coupled in rotational relation to the scanning mirror  68  and by the number and size of the mirror sides or facets. It should be understood that the polygonal mirror  68  could be implemented as a galvanic scanner without departing from the scope of this invention. 
     Light or electromagnetic energy is reflected by the scanning mirror  68  in scanning relation and is directed toward the region of sight as a flying spot which proceeds in transverse relation to the flow direction  14  ( FIG. 1 ), that is in a direction generally indicated by the arrow  70 . The articles in the product stream  12  ( FIG. 1 ) containing acceptable articles  16  and undesirable articles  18  interact with a portion of the light or electromagnetic energy projected by the scanning mirror  68 . A portion of other light or electromagnetic energy that has passed by articles in the product stream  12  interacts with the background element  42 . 
     Some of the light or electromagnetic energy interacting with the background element  42  and interacting with articles in the product stream  12  is returned by reflection and refraction to the scanning mirror  68 . A portion of the light or electromagnetic energy is converted into a longer or shorter wavelength by a fluorescence and/or Raman mechanism during its interaction with some of the articles in the product stream  12 . This converted light or electromagnetic energy is emitted by the articles and a portion is propagated or travels also to the scanning mirror  68 . 
     The returned light or electromagnetic energy is reflected by the scanning mirror  68  and directed toward the mirror  64 . Here, the light or electromagnetic energy is reflected as returned light or electromagnetic radiation beam and is designated by the numeral  72 . The returned light beam  72  is reflected by the return light mirror  74  where it is bent towards a plurality of optical processing elements which will be discussed in further detail below. 
     The returned light  72  interacts with a spectral splitter  76  which reflects a substantial amount of light or electromagnetic energy having a shorter wavelength than a cutoff wavelength and passes a substantial amount of light or electromagnetic energy having a longer wavelength than the cutoff wavelength. The spectral splitter  76  may be implemented as a dichroic mirror or other type of filter that is known in the art. A substantial portion of the light or electromagnetic energy from the returned light beam  72  having a longer wavelength than the cutoff wavelength passes through the spectral splitter and interacts with a spectral filter  78 . The spectral filter  78  is utilized to further refine the spectral content of the light or electromagnetic energy passing therethrough thereby providing a useable signal which is representative of the fluorescing properties of any articles that have interacted with the scanning beam of light or electromagnetic radiation. In one embodiment of the invention, the cutoff frequency of the spectral splitter  76  is 670 nm and the spectral filter  78  is configured to pass frequencies having a wavelength less than 760 nm. Preferably in this embodiment of the invention, the light or electromagnetic radiation that has interacted and passed through the spectral filter  78  will have a desired spectral content having a substantial portion of spectral energy residing at wavelengths between 670 and 760 nm. 
     The light or electromagnetic energy that passes through the spectral filter  78  is received by a sensor  80  and is converted into a voltage signal that is substantially proportional to the magnitude of the light or electromagnetic energy impinging on its surface. The voltage signal from the sensor  80  is amplified by the fluorescence channel amplifier chain  82  contained as part of the sorting processor  46  which delivers a time varying amplified signal. The signal from the fluorescence channel amplifier chain  82  is transferred to the input of a fluorescence channel analog to digital converter  84  where the signal is digitized and otherwise converted into a digital format. The digitized signal from the fluorescence channel analog to digital converter  84  is routed to a port “F” on the computer  86  as a stream of digital data. 
     Light or electromagnetic energy that has been reflected by the spectral splitter  76  is directed to a splitter  88 . The spectral content of this light contains a preponderance of energy having a wavelength shorter than the cutoff wavelength of the spectral splitter  76 . In the embodiment noted above, and with the cutoff wavelength equal to 670 nm, the spectral content of this light will have the vast majority of its spectral energy having a wavelength that is shorter than 670 nm. This light or electromagnetic energy interacts with the beam splitter  88  which acts to divide the light or electromagnetic radiation, passing approximately half of the energy and reflecting the other half of the energy. 
     The reflected portion of the light or electromagnetic radiation interacts with a bandpass filter  89  that is configured to pass light having a spectral content substantially similar to the spectral content of the light source  60 . The light or electromagnetic energy that passes through the bandpass filter  89  is received by a sensor  90  and is converted into a voltage signal that is substantially proportional to the magnitude of the light or electromagnetic energy impinging on its surface. The voltage signal from the sensor  90  is amplified by the reflectance channel amplifier chain  92  contained as part of the sorting processor  46  which delivers a time varying amplified signal. The signal from the reflectance channel amplifier chain  92  is transferred to the input of a reflectance channel analog to digital converter  94  where the signal is digitized and otherwise converted into a digital format as a stream of digital data. The digitized signal from the reflectance channel analog to digital converter  94  is routed to a port “R” on the computer  86 , and represents light or electromagnetic radiation that has been reflected by the articles. 
     The passed or transmitted portion of the light or electromagnetic radiation from the beam splitter  88  then interacts with a filter or field stop  96 . The field stop  96  is configured to block light or electromagnetic energy that has been returned in an area of the center of the beam and pass any energy outside this area. In one embodiment, the field stop  96  comprises a ‘Mercedes’ (trademark) sign shaped diaphragm. 
     The light or electromagnetic energy that passes through the field stop  96  then interacts with a bandpass filter  97  that is configured to pass light having a spectral content substantially similar to the spectral content of the light source  60 . The light or electromagnetic energy that passes through the bandpass filter  97  is received by a sensor  100  and is converted into a voltage signal that is substantially proportional to the magnitude of the light or electromagnetic energy impinging on its surface. The voltage signal from the sensor  100  is amplified by the scatter channel amplifier chain  102  contained as part of the sorting processor  46  which delivers a time varying amplified signal. The signal from the scatter channel amplifier chain  102  is transferred to the input of a scatter channel analog to digital converter  104  where the signal is digitized and otherwise converted into a digital format as a stream of digital data. The digitized signal from the scatter channel analog to digital converter  104  is routed to a port S of the computer  86 . For the purpose of this disclosure, the light or electromagnetic radiation that is detected by sensor  100  is referred to as being scattered by the articles because it represents light and electromagnetic energy that has been returned that lies outside a region of the area blocked by the field stop. 
     In one embodiment, the sensors  80 ,  90 , and  100  are each photomultiplier tubes. However, other types of sensors may be useful in this or other applications without departing from the scope of this invention. 
     One skilled in the art would recognize that there are other ways that the data streams from the fluorescence channel, scattering channel, and reflectance channel could be obtained without departing from the scope of this invention. For example, other combinations of filtering elements could be re-arranged by adjusting various optical properties of the filter elements to produce similar results. 
     The computer  86  contains elements that are effective in processing data from the fluorescence, reflectance and scatter channels to provide real-time classification of articles in the product stream  12  as they pass through the region of sight  26  and further contain elements to provide the removal signals  29  which command the individual valves in the ejector manifold  28  to project fluid pulses from the ejector nozzles  30  to selectively remove undesirable articles  18  from the product stream  12 . The configuration of parameters useful in the classification process are provided by the interaction of an operator or user (not shown) and the user interface  24 . 
     Referring now to  FIG. 3 , the user interface  24  is provided which is operable to display information gathered by the scanning assembly  36  and processed by the computer  86  to an operator. From this information, an operator (not shown) is able to adjust the criteria that are utilized by the computer  86  to differentiate between acceptable articles  16  and undesirable articles  18 . In addition, the user interface is operable to display and illustrate to the operator how the computer  86  would process the articles and further to provide a visual indication of which articles are acceptable and which articles are undesirable. In this manner, it is possible for an operator to configure the sorting apparatus  10  with the capability of making subtle distinctions between articles that other sorting machines found in the art cannot make on a repeatable basis. In addition, the sorting criteria can be saved as a distinct setup or recipe by an operator. This setup or recipe can be recalled at a later time, providing for rapid switching between various types of articles, or to respond to other variations within the product stream  12 . 
     Referring now to  FIGS. 2 and 3 , the computer  86  is further operable to provide image data of articles in the product stream  12  for display on the user interface  24  as shown on the right hand display  150  of  FIG. 3 . This image data is produced by assembling and transforming data from the fluorescence, scatter, and reflection channels. In one embodiment, this transformation is accomplished by assigning specific display colors to each channel, thereby representing the image in a virtual color environment while preserving the spatial relationships of articles in the product stream, having gleaned this information from the timing and scanning parameters of the individual channel data streams. 
     In one embodiment, the fluorescence channel is assigned as the color “green”, the scatter channel is assigned the color “red”, and the reflection channel is assigned the color “blue”. In this transformation environment, the background element  42  is displayed as solid red since it does not emit, and does not fluoresce and is selected to provide a high degree of scattering. An article with abundant fluorescence (for example, an article with chlorophyll like peas) will be displayed as a green article in the user interface  24 , and is shown in  FIG. 3  using diagonal hatching pattern and is indicated by the numeral  152 . An article such as a pea pod, has less fluorescence, and will be displayed on the user interface  24  in darker color, and is shown in  FIG. 3  with a speckled hatch pattern and is indicated by the numeral  153 . An article such as a stone or other dark colored foreign material will be displayed in a black color on the user interface  24  since they do not fluoresce and have relatively low scattering and specular reflective properties, and are shown in  FIG. 3  in a densely hatched pattern and is indicated by the numeral  156 . Articles such as metal which having a high degree of specular reflectivity are displayed in blue on the user interface  24 , and are shown with a cross hatching pattern and are generally indicated by the numeral  157 . Articles such as certain types and colors of plastics and soft transparent rubber are displayed on the user interface in a purple color since they exhibit a high degree of scattering, and are shown in a light speckle hatching pattern as generally indicated by the numeral  154 . 
     The user interface  24  and computer  86  are equipped with hardware and computer readable programs to enable an operator (not shown) to configure a segmentation or classification engine (not shown) by assigning individual colors to acceptable regions and undesirable regions. In this way, the operator is able to teach the sorting apparatus  10  to designate certain articles in the product stream  12  as acceptable articles  16  and undesirable articles  18 . The left hand graphic window  170  in FIG.  3  displays the results of this segmentation or classification operation as a classification image, providing valuable feedback to the operator. In one embodiment, the objects detected to be acceptable articles generally indicated by the numeral  171  are displayed as white on the user interface  24 , and in  FIG. 3  are shown without hatching. Articles that are detected and determined to be undesirable articles are shown in blue on the user interface  24 , and in  FIG. 3  are shown in a cross hatched pattern as generally indicated by the numeral  173 . The computer  86  is configured to combine the scatter and reflection signals to determine the background signal which is represented by the color grey on the user interface  24 . 
     Operation 
     The operation of the present invention is believed to be readily apparent and is briefly summarized in the paragraphs which follow. 
     Articles in the product stream  12  are conveyed on the endless belt  22  of the conveyor  20 . Light or electromagnetic radiation having a first wavelength is provided by the optical scanner  36  and is directed toward articles in the product stream  12  by the mirror  38 . Light or electromagnetic radiation that is reflected, refracted or converted by fluorescent or other emission is returned to the mirror  38 , and to the optical scanner  36 . Some of the light that is not returned, interacts with the background element  42 , where a portion is returned to the mirror  38 , and to the optical scanner  36 . 
     Light or electromagnetic radiation that is returned from articles in the product stream  12  having a wavelength that is longer than the first wavelength is converted into a first signal by the optical scanner  36 . Light or electromagnetic radiation having the first wavelength that is reflected by articles in the product stream  12  and from the background element  42  is converted into a second signal by the optical scanner  36 . Light or electromagnetic radiation having the first wavelength that is scattered by articles in the product stream  12  and from the background element  42  is converted into a third signal by the optical scanner. 
     Then, the first, second, and third signals are transformed into a first, second, and third data streams representing the time varying magnitude of each of the signals, and represent the fluorescence channel, reflectance channel, and scatter channel respectively. The data streams are presented to the computer  86  and processed in a manner that will be discussed in more detail below. 
     Referring to  FIGS. 4 and 5  each include a set of time ordered charts representing data formed into a trace from one scan line of the scanning assembly  36  ( FIG. 2 ) of the data streams presented to the computer  86 . Now referring to  FIGS. 3 ,  4  and  5 , the reflectance channel “R” is shown in  FIG. 4 , and is designated by the numeral  200 . The scatter channel “S” is shown in  FIG. 5 , and is designated by the numeral  300 . The fluorescence channel “F” is shown in  FIG. 4 , and is designated by the numeral  230 . 
     The notches  202  and  212 ,  302 ,  312 , and peaks  232  and  234  are realized as articles pass through the region of sight  26  ( FIGS. 1 ,  2 ). In this example, these articles exhibit low reflectance, low levels of scattering, and high levels of fluorescence. In this example, these articles are peas and are displayed in a green color (diagonal hatching) on the user interface  24  because of their high level of fluorescence, and are designated by the numeral  152  ( FIG. 3 ). Other materials which exhibit similar characteristics could include beans and spinach greens. In addition, articles such as pea pods are displayed in a darker shade of green (shown with small triangle hatching) and are designated with the number  153 . In this case, it is possible for an operator to configure the sorting apparatus  10  to differentiate between various types of articles based on fluorescence, scattering, and reflective properties so, as an example, pea pods could be differentiated and sorted from peas in a product stream  12 . 
     The peaks  204 ,  208 ,  210  and  214 , and the notches  304 ,  308 ,  310 , and  314  are realized as articles pass through the region of sight  26  having high reflectance, scattering and little or no fluorescence. In this example, these articles are blank or untreated wood, white translucent stone or colored plastics and are displayed on the user interface  24  in a mixture of red and blue yielding various shades of purple. These articles are shown in a speckled hatching format, and designated by the numeral  154 . Materials exhibiting these properties could include blank or untreated wood. 
     The notches  206  and  306  are realized as an article passes through the region of sight  26  having a dark, non-reflecting and non-scattering characteristic with little or no fluorescence. In this example, this article is a piece of black rubber and is displayed on the user interface  24  as a dark or black color. This article is shown in dense cross shading, and designated by the numeral  156 . 
     All other points along the traces  200 ,  230 , and  300  result from light or other electromagnetic energy interacting with the background element  42  ( FIGS. 1 ,  2 ). This background element  42  exhibits a high degree of scatter, a mid level of reflectivity and no appreciable fluorescence. The background element  42  is visible on the user interface  24  and appears as a red color on the user interface, and is designated by the numeral  158 . 
     The computer  86  ( FIG. 2 ) is programmed and operable to utilize data from the reflectance channel “R”, and the scatter channel “S”, to provide a determination regarding whether the returned light or electromagnetic radiation has interacted with the background. This determination is accomplished by comparing a previously trained and internally stored nominal background data stream or set with data from the reflectance channel “R” and the scatter channel “S”. This previously trained background data stream or set represents the measured background level during a setup operation. The “B” trace  220  is a representation of this determination, with a high level  222  indicating the interaction with the background element  42 , while a low level  224  indicates an interaction with articles in the region of sight  26  rather than an interaction with the background element  42 . 
     Yet further, a time ordered chart representing a logical combination of the fluorescence channel having exceeded a threshold, and logically AND&#39;ed with the compliment of the background signal  220  is shown in the trace  240 . Here, the peaks  242  and  244  represent peas that have passed through the region of sight  26  and are designated as acceptable articles  16 . 
     Next, a trace  250  is shown being a logical combination of the background trace  220  and the trace  240 . Notches  252 ,  254 ,  256 ,  258 , and  260  represent undesirable articles  18 . 
     Finally, a trace  320  is shown being a logical combination of the scatter channel trace  300 , background trace  220  and the trace  240 . Here the notch  322  corresponds to the article  156  as displayed on the user interface, which could similarly be designated as an undesirable article  18 . As noted earlier, the computer  86  is operable to act to remove the undesirable article  18  by generating a command which controls a specific valve in the ejector manifold  28  to direct blasts of fluid at the unacceptable article  18  to effectively remove it from the product stream  12 . 
     In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.