EP0402543B1 - Tri optique d'objets - Google Patents

Tri optique d'objets Download PDF

Info

Publication number
EP0402543B1
EP0402543B1 EP19890305989 EP89305989A EP0402543B1 EP 0402543 B1 EP0402543 B1 EP 0402543B1 EP 19890305989 EP19890305989 EP 19890305989 EP 89305989 A EP89305989 A EP 89305989A EP 0402543 B1 EP0402543 B1 EP 0402543B1
Authority
EP
European Patent Office
Prior art keywords
radiation
acceptable
viewing zone
electric signal
signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP19890305989
Other languages
German (de)
English (en)
Other versions
EP0402543A1 (fr
Inventor
Roger Frederick Bailey
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to EP19890305989 priority Critical patent/EP0402543B1/fr
Priority to DE1989626537 priority patent/DE68926537T2/de
Publication of EP0402543A1 publication Critical patent/EP0402543A1/fr
Application granted granted Critical
Publication of EP0402543B1 publication Critical patent/EP0402543B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07C—POSTAL SORTING; SORTING INDIVIDUAL ARTICLES, OR BULK MATERIAL FIT TO BE SORTED PIECE-MEAL, e.g. BY PICKING
    • B07C5/00—Sorting according to a characteristic or feature of the articles or material being sorted, e.g. by control effected by devices which detect or measure such characteristic or feature; Sorting by manually actuated devices, e.g. switches
    • B07C5/34—Sorting according to other particular properties
    • B07C5/342—Sorting according to other particular properties according to optical properties, e.g. colour
    • B07C5/3425—Sorting according to other particular properties according to optical properties, e.g. colour of granular material, e.g. ore particles, grain

Definitions

  • THE PRESENT INVENTION relates to an optical sorting apparatus and method for sorting, respectively distinguishing unacceptable objects from acceptable objects, the objects being e.g. beans, nuts, seeds or other agricultural products.
  • these apparatus include a feeding device which separates a quantity of objects into individual streams of moving objects.
  • the object streams pass through viewing zones where the individual objects are illuminated.
  • Light reflected from each of the illuminated objects is collected by one or more photo-amplifiers and analyzed to determine if the object is acceptable.
  • each photo-amplifier responds to a region of the light frequency spectrum.
  • the photo-amplifiers produce electric signals which are proportional to the intensity of the light detected.
  • the electric signals are processed by an electronic circuit which determines whether a given object is acceptable based on its electric signal.
  • the electronic circuit activates a rejection mechanism that separates an unacceptable object from the object stream when the unacceptable object is detected.
  • the color reference provided by a painted background must typically match the acceptable color as predetermined for a particular type of object to within a 1 to 1.5% tolerance. Consequently, numerous backgrounds are necessary given the wide variation in colors for different types of objects. For example, when known sorting devices are used to sort peanuts and then coffee beans a change of painted backgrounds is required. Likewise, to switch from sorting one grade of coffee bean to another a change of backgrounds is required. Further, determining the appropriate color reference for a particular type of object may require extensive research.
  • Painted backgrounds in known sorting apparatus deteriorate and get dirty thereby causing problems.
  • the color of a deteriorated or dirty background frequently does not match the color reference for acceptable objects that it was designed to match. Consequently, when acceptable objects are optically compared to deteriorated or dirty backgrounds the acceptable objects may be rejected.
  • Viewing heads for known optical sorting apparatus are relatively bulky for the viewing area they provide. For example, a viewing head with a 30 cm outside diameter may provide only a 5 cm viewing zone. The diameter disparity is necessary to allow the viewing head to accommodate lamps for illuminating the viewing zone as well as space intensive equipment such as lenses, photo-amplifiers and filters. Lamps used in known viewing heads also generate a substantial amount of heat which affects response characteristics of the photo-amplifiers and causes deterioration of the backgrounds. The amount and proximity of equipment provided in known viewing heads creates additional problems such as limiting the number of viewing channels available due to a lack of space, and causing electrical interference in the photo-amplifier circuits due to the lamp power-circuits.
  • EP-A-0 223 446 which provides separation of the light sources and/or the detecting means from the viewing zone by the use of optical fibres to carry light to and/or from the viewing zone.
  • Known optical sorting apparatus also have the problem of rejecting an acceptable object when defects are detected in the proximate end of a nearby, unacceptable object. This problem typically occurs in two ways. First, imprecision in the timing mechanism may cause the rejection of an acceptable object passing through the viewing zone either immediately before, or after, the defective object. Second, known viewing mechanisms may associate a defect at either end of an unacceptable object with both the unacceptable object and an acceptable object passing through the viewing zone either immediately before, or after, the unacceptable object. These problems particularly occur when the objects being sorted are bunched together in the product stream - i.e., when the spacing between objects is small.
  • Faulty alignment of viewing heads and viewing assemblies in known sorting apparatus also leads to incorrect sorting operations.
  • Two forms of alignment are necessary for proper sorting.
  • the viewing head is aligned with respect to the object stream. This may need to be done on a regular basis, particularly when the device is used to sort a wide range of objects.
  • each viewing assembly is separately adjusted with respect to the viewing head and object stream. The viewing assemblies ideally are adjusted to form a flat circle around the object stream. This insures that all views are synchronized, resulting in actuation of the rejection mechanism at substantially the same time regardless of which viewing assembly actually sees the defect in an unacceptable object.
  • the invention provides a method and apparatus for sorting and separating objects such as agricultural products based on optically discernible characteristics or "defects", and as defined in the appended claims.
  • the invention provides an optical sorting apparatus whioh alleviates the disadvantages and problems of known sorting apparatus.
  • the invention does not use painted or other backgrounds as color references to provide a comparative reflective surface for optically determining if an object is acceptable. Instead, a number of pre-selected acceptable objects are optically viewed and a reference electric signature for the photo-amplifier signals from the acceptable objects is obtained and stored in memory.
  • a microcomputer compares the electric signal for a viewed object with the stored electric signature for acceptable objects and activates the rejection mechanism when they do not match within operator determinable limits.
  • the operator of the sorter simply repeats the electric signature procedure with pre-selected acceptable objects of the new type.
  • the electric signature can be reset when switching from peanuts to coffee beans, or even from one type of coffee bean to another.
  • the lack of painted backgrounds reduces or eliminates the need for extensive laboratory research to find the right color reference for a particular type of object.
  • problems associated with deteriorated or dirty backgrounds are eliminated by the absence of painted backgrounds.
  • the invention addresses problems that result from the amount and proximity of equipment packed into viewing heads of known apparatus, and problems caused by the bulkiness of the viewing heads.
  • the invention uses optical fibers for transmitting both the illuminating light and the detected light.
  • the lamps, photo-amplifiers, filters and electrical circuitry are located remote from the viewing head. Consequently, only the lenses and the ends of the optical fibers are located in the viewing head thereby reducing or eliminating the crowding and bulkiness of known viewing heads. Further, this arrangement reduces problems due to heat effects on the photo-amplifiers from the lamps because the lamps are separated from the photo-amplifiers. Likewise, electrical interference to the photo-amplifier circuits from the lamp power-circuits is reduced or eliminated. Additionally, the reduction or elimination of clouding in the viewing head makes it possible to add more viewing assemblies than would otherwise be feasible with viewing heads for known sorting apparatus.
  • Improper rejection of acceptable objects due to bunching of objects in the object stream is alleviated by the invention.
  • the use of light photo-amplifiers along with two sets of infrared (IR) photo-amplifiers enables a more precise measurement of size and rate of fall of a defective object than is possible with known sorting apparatus and reduces or eliminates imprecise activation of the rejection mechanism.
  • the two sets of IR photo-amplifiers are positioned in different planes perpendicular to the object stream and allow a precise measurement of the rate of fall as determined by the time it takes an individual object to fall past those two points.
  • the rejection mechanism is then activated based upon the exact rate of fall as calculated by a microcomputer.
  • the combination of signals from the visual and IR detectors associate a defect with the corresponding object by determining the presence and size of the object as it is viewed. This contrasts with known apparatus which can only determine the presence of a defect, but can not associate the defect with an object because the acceptably colored part of the object cannot be distinguished from the background.
  • the invention also overcomes problems due to clouding of the viewing lenses or windows with dirt. This is accomplished by monitoring the intensity of the IR detector signals when no object is being viewed. As clouding occurs, the strength of the IR signal decreases and the microcomputer system adjusts to compensate for the signal loss due to clouding. When maximum compensation has been made, the microcomputer system indicates that the viewing lenses and windows need cleaning. This reduces shutdowns for frequent cleaning, as well as reducing or eliminating improper rejection of acceptable objects when the viewing lenses or windows are dirty.
  • Known optical sorters use photo-amplifier lenses with a fixed focal point. This may cause rejection of acceptable objects in certain situations. For example, if an acceptable object does not fall exactly through the focal point of the photo-amplifier lens, the corresponding signal may be inaccurate. This occurs because the lens views a larger area of the object than would otherwise occur if the object fell exactly through the focal point and the size of the area viewed of an object may affect the intensity of detected light.
  • the invention attacks this problem by focusing lenses at infinity. Consequently, the same signal is produced regardless of where an object falls relative to the photo-amplifier lens because it views the same size area of the object regardless of the object's proximity to the lens.
  • the invention also has the ability to determine how long the object was outside the acceptable level as determined by the operator.
  • the operator also has the ability to determine how long, and how many times, each object will be allowed to exceed the acceptable level of object color.
  • the operator also has the ability to adjust the electronics to allow any combination of viewing assemblies to register the defect.
  • the present invention allows the ability for more than one photo-amplifier to detect the color exceeding this operator adjusted level before the object is determined as being unacceptable.
  • the combination may be "any” to see, “all” to see, or any combination of photo-amplifiers based on their relationship to each other.
  • the operator has an almost infinite ability to accept or reject objects based on object size and shape as well as defect size and shape and the number and location of the defect(s) on each object.
  • the operator also has the ability to reject an object that has no defects and accept an object that has any defect.
  • the present invention has the ability to operate one or more rejection mechanisms per viewing area. These rejection mechanisms may be selected so that one rejects only the color defects and another rejects only the size defects. However, it must be realised that the operator independently has the ability to combine size of the object, the shape of the object, the size of the defect, the shape of the defect, position and number of each defect of unacceptable colors with any or all of the rejection mechanisms.
  • the present invention has the ability to accept dark brown defects that are of small size and reject dark brown defects that are of large size. Or the opposite if decided by the operator. This ability is not available in current apparatus.
  • the time delay and duration of the operation of the rejection mechanism is preset for the type of object to be rejected.
  • the present invention allows the rejection mechanism to be individually adjusted for each object.
  • the output from an IR photo-amplifier beam located in a plane below or above a red and green viewing area of the viewing head is compared with the output of another IR photo-amplifier which is synchronized to the red and green photo-amplifiers, and the two IR outputs are used to give a time lapse for an object to pass between the first and second IR beam.
  • This time duration is then stored in memory and used to determine the proper time to start the rejection mechanism. This starting time varies for each object as determined by the speed of the object through the viewing zone.
  • the rejection mechanism remains on for the proper time to reject each defective object.
  • the duration of this "on time” will vary for each defective object because of variations in the individual object lengths, and the "on time” is determined as a function of the detecting and signal processing circuits.
  • the operator has the ability to adjust the "on time” as a function of object length, but it must be realised that the actual "on time” of the rejection mechanism may vary for each object to be rejected.
  • results may be stored by the present invention and these may include, but are not limited to, the number of objects rejected for each set of criteria including individual colors, location of defect(s), number of defects, size of defects, and size, shape and orientation of the object.
  • the invention has the ability to automatically adjust the feeder mechanism to maintain a constant throughput.
  • alarm messages are available to the operator that will indicate abnormal operation. These include, but are not limited to, dirty glass, too may objects of a certain type being rejected, reject mechanism operating erratically, no air pressure, illuminating lamp(s) not bright enough, and insufficient or too many objects being conveyed. The operator has the ability to override these alarm situations or correct them.
  • the invention requires significantly less illumination than is required in known sorting apparatus.
  • known sorting apparatus the entire viewing zone is illuminated to provide sufficient reflected light from the object and background for the photo-amplifiers.
  • the apparatus of the invention illuminates only the object because there is no background that needs to be illuminated. Consequently, the lamp power required for the apparatus for the invention is less than is required for known sorting apparatus.
  • FIG. 1 is a perspective view of a viewing head for an embodiment of the present invention.
  • FIG. 2 is a cross-sectional view of the viewing head of FIG. 1 taken along the section lines II-II of FIG. 1.
  • FIG. 3 is a schematic diagram of the signal processing means.
  • FIG. 1 a perspective drawing of a viewing head 1 of the optical sorting apparatus for the invention is shown.
  • FIG. 2 likewise, shows a cross-sectional view of the viewing head 1.
  • the viewing head 1 encloses a cylindrical viewing zone 2, and objects to be viewed move axially through the center of the viewing zone 2 in an object stream.
  • the viewing head a includes four illuminating assemblies 3-6; two combination viewing/IR assemblies 7 and 8; and two IR assemblies 9 and 10.
  • the viewing/IR assemblies 7 and 8 are preferably arranged in the viewing head 1 parallel to the end faces of the viewing head, and each viewing/IR assembly points to the center of the viewing zone 2.
  • the illuminating assemblies 3 and 5 are arranged in the viewing head directly above the viewing/IR assemblies 7 and 8, respectively, such that the path of the light projected by the illuminating assemblies and reflected by an object in the viewing zone forms an acute angle between the illuminating assemblies and the viewing/IR assemblies where the vertex of the angle is located at the center of the viewing zone.
  • the illuminating assemblies 4 and 6 are located directly below viewing/IR assemblies 7 and 8 respectively, such that the light projected from them forms an acute angle with the vertex at the center of the viewing zone. This arrangement helps to insure that no light is collected by the viewing/IR assemblies 7 and 8 unless some part of an object is in the center of the viewing zone 2 and reflects that light to the viewing/IR assemblies.
  • the illuminating assemblies 3-6 are connected to one end of optic fiber bundles 11-14, respectively. Each illuminating assembly 3-6 is supplied with light via optic fiber bundles 11-14 from a commercially available light source 19 remote to the viewing head 1. Light from the light source 19 is transmitted into the ends of optic fiber bundles 11-14 that are remote to the viewing head 1 by a light source focusing means 20.
  • the light source focusing means 20 comprises a series of lenses to collect, focus, and project light from the light source to the ends of the optic fiber bundles.
  • the light source 19 may provide white light and comprise a quartz halogen incandescent lamp. Alternately, the light source may be replaced by a substantially monochromatic light source such as an array of light emitting diodes (LEDs). The LED array may be selected to provide an output having any convenient light frequency or color.
  • a substantially monochromatic light source such as an array of light emitting diodes (LEDs).
  • the LED array may be selected to provide an output having any convenient light frequency or color.
  • the optic fiber bundles 11-14 are formed from individual optic fibers and may have any suitable length and cross section.
  • the optic fibers may comprise glass or plastic, or other suitable material.
  • the viewing/IR assemblies 7 and 8 are connected to one end of optic fiber bundles 15 and 16, respectively.
  • IR assemblies 9 and 10 are connected to one end of optic fiber bundles 17 and 18, respectively.
  • Each optic fiber bundles 15-18 comprises multiple optic fibers of any suitable length and cross section which may comprise glass, plastic, or other suitable material.
  • the lens sets for illuminating assemblies 3-6 transmit light from optic fiber bundles 11-14 to the viewing zone 2, and each set is designed to focus light on the center of the viewing zone.
  • the lens sets for viewing/IR assemblies 7 and 8 collect light reflected from objects in the viewing zone 2 and transmit it to optic fiber bundles 15 and 16. Each viewing/IR assembly lens set is preferably designed for infinite focus at the viewing zone end.
  • the lens set for viewing/IR assembly 7 also collects IR from the viewing zone 2, and the lens set for viewing/IR assembly 8 also transmits IR to the viewing zone 2.
  • the lens set for IR assembly 9 collects IR from an area below the viewing zone 2, and the lens set for IR assembly 10 transmits IR to the same area below the viewing zone 2.
  • Each assembly, 3-10 may require multiple lens sets to cover the end face of the corresponding optic fiber bundles 11-18. If multiple lens sets are used in an assembly they may be staggered in an arrangement like 'bricks' to minimize the occurrence of blind spots.
  • the lens arrays 21 and 22 collect and focus the light and project it into dichroic filters 23 and 24.
  • dichroic filters separate light into two beams of different frequency.
  • Dichroic filters contain a material that passes light above a certain frequency but reflects light below that frequency.
  • the dichroic material is positioned in the filter at a 45 degree angle to the path of the entering light, and consequently, the reflected light emerges from the filter at a 90 degree angle from the path of the entering light while the non-reflected light passes straight through the filter.
  • Dichroic filters 23 and 24 use a material that reflects IR but passes light with frequencies higher than IR. Thus, dichroic filter 24 reflects IR transmitted to it by viewing/IR assembly 7 and passes light above that frequency which is transmitted to it by viewing/IR assembly 7. Dichroic filter 23, however, is used to project IR into optic fiber bundles 16 and 18. IR from an IR generator 27 is projected into the dichroic filter 23 such that it is transmitted via the optic fiber bundles 16 and 18 to the viewing zone 2. It should be appreciated that dichroic filter 23 receives light from the viewing zone 2 via optic fiber bundle 16 and passes this light.
  • dichroic filters 25 and 26 use a material that separates the light into two beams so that the beam that is passed includes “green” light and the beam that is reflected includes “red” light. Thus, dichroic filters 25 and 26 each produce a “red” and “green” beam of light. The individual beams of "red” and “green” light are directed to separate photo-amplifiers.
  • Fiber optic bundle 17 transmits IR collected by the lens set of IR assembly 9 to lens array 28.
  • Lens array 28 collects and focuses the IR for transmittal to a photo-amplifier.
  • More illuminating assemblies and viewing/IR assemblies may be necessary or desirable depending on the size, shape, and nature of the object being viewed. Generally, sufficient illuminating assemblies and associated viewing/IR assemblies are required to view substantially all of the surface area of the objects being sorted. For example, four sets of assemblies with each set comprising two illuminating assemblies and one viewing/IR assembly may be spaced at 90 degree increments around the circumference of the viewing head.
  • the red and green light from each assembly is separated into individual red and green beams, respectively. Further, all IR collected by viewing/IR assemblies is separated into individual beams, and all IR that is collected by IR assemblies may be separated into individual beams.
  • the system of illuminating assemblies and associated optic fiber bundles, lens sets, lens array, and light source along with the viewing/IR assemblies and associated optic fiber bundles, lens sets, lens arrays, and dichroic filters comprise a detecting means.
  • the detecting means optically detects discernible defects in objects being sorted.
  • the detecting means may be multichromatic or monochromatic. If a monochromatic detecting means is used then the dichroic mirrors 25 and 26 for separating light into two beams of different frequency are eliminated. It should be appreciated that a multichromatic detecting means may separate light at any frequency desired and may effect multiple separations as desired to optimize its ability to detect defects in a particular type of object.
  • the system of IR assemblies and viewing/IR assemblies and associated optic fiber bundles, lens sets, lens arrays, dichroic filters, and IR generator comprise an object sensing means.
  • the object sensing means determines the presence, size, and rate of fall of an object being sorted.
  • the sensing means may comprise electromagnetic energy other than IR as appropriate depending on the electromagnetic energy used for the detecting means and the nature of the objects being sorted.
  • the object sensing means comprises at least two separate sets of IR beams. Any number of IR beams may be used in each set, particularly where variation in object size is relatively large. For example, two IR beams may be arranged at a 90 degree angle such that the two IR beams intersect with each other and with the path of the object stream. The second set of IR beams is located such that it intersects the object stream in a plane that is different than the plane of the first set of IR beams.
  • the object to be sorted is introduced to the viewing zone and as the object passes through the viewing zone it intersects the first IR beam which determines the presence of an object in view and how long it takes the object to traverse the viewing zone.
  • the signal from the viewing zone IR photo-amplifier will decrease proportionately to the degree of blockage caused by the section of the object in view, and if no decrease is detected then no object is in view.
  • the output of the viewing zone and subviewing zone IR photo-amplifiers is therefore capable of determining when an object first enters the viewing area, how wide it is at any point of its length, and how long it is.
  • the red and green photo-amplifiers are determining the color of the section of the object in view.
  • the outputs of the IR photo-amplifiers and the red and green photo-amplifiers are continuously processed and the result compared to the previously stored electric signature for acceptable objects.
  • the red beam 41, green beam 42, viewing zone IR beam 43, and subviewing zone IR beam 44 are detected by photo-amplifiers 45, 46, 47, and 48 which generate signals 49, 50, 51 and 52.
  • These signals 49, 50, 51, and 52 are proportional to the intensity of the red beam 41, green beam 42, and IR beams 43 and 44 detected by the respective photo-amplifiers 45, 46, 47, and 48.
  • the operator has the ability to individually adjust each of the signal strengths for the four signals 49, 50, 51, and 52 by adjusting gain adjusters 53, 54, 55 and 56 to produce signals 57, 58, 59 and 60.
  • the gain adjusters 53, 54, 55 and 56 may also include amplifiers. It may be necessary to increase or decrease the signal strength for signals 49 and 50 from red and green photo-amplifiers 45 and 46 depending on the intensity of the defects on the objects to be sorted.
  • the gain adjusters 55 and 56 may be used to increase the signal strength for signals 51 and 52 for IR beams 43 and 44 depending on the degree of blockage of the beams caused by the average size of the object to be sorted. For example, if the size of the object is almost the full width of the beam, the gain will need to be increased to compensate for the reduced amount of IR beam not blocked by the object.
  • signals 57 and 58 from the red and green photo-amplifiers 45 and 46 are zero and signal 59 is at its maximum value because no object is present to reflect light and block the viewing zone IR beam. Similarly, when no object blocks the subviewing zone IR beam, signal 60 is at its maximum value.
  • Switch 61 produces signals 62 and 63 when it is in the on position, and also clears both analog memories 67 and 68. Signals 62 and 63 are fed to 3-way AND gates 64 and 65, respectively. Signal 57 is converted by an analog to digital converter to a digital signal and fed to 3-way AND gate 64. Signal 58 is also converted by an analog to digital converter and fed to 3-way AND gate 65. It should be appreciated that the analog to digital converters for signals 57 and 58 will only give a positive digital signal when signals 57 and 58 give a positive, analog signal indicating that red or green beams of light are being detected, respectively.
  • Signal 66 which is derived from signal 59 for the viewing zone IR beam, is also converted by analog to digital converters and fed into both 3-way AND gates 64 and 65. Again, the analog to digital converters for signal 66 will only give a positive, digital signal when signal 66 is a positive, analog signal indicating the presence of an object in the viewing zone that is blocking the viewing zone IR beam.
  • 3-way AND gates 64 and 65 receive positive, digital signals from each of their three inputs, they generate an enabling signal to the red and green analog memories 67 and 68, respectively.
  • signals 57 and 66 in analog form are fed to multiplier 69, and signals 58 and 66 in analog form are fed to multiplier 70.
  • Multiplier 69 multiplies signal 57 by signal 66 to produce signal 71.
  • Multiplier 70 multiplies signal 58 by signal 66 to produce signal 72.
  • Signals 71 and 72 are fed to amplifiers and then fed to the red and green analog memories 67 and 68, respectively.
  • the object to be sorted is conveyed through the viewing zone.
  • a signal 71 will be generated as described above but for the object to be sorted.
  • Signal 71 is then split and fed to steering diodes 73 and 74. If signal 71 is positive, steering diode 73 allows the positive amplitude of the signal to pass on to comparator 77, which also contains an AND gate, otherwise the output of steering diode 73 is zero. If signal 71 is negative, steering diode 74 allows the negative amplitude of the signal to pass on to comparator 78, which also contains an AND gate, otherwise the output of steering diode 74 is zero.
  • the output signal 79 which is the red electric signature of the red analog memory 67 is continuously fed to both comparator 77 and comparator 78.
  • Comparators 77 and 78 generate signals 80 and 81 which are proportional to the difference between the red electric signature and the signals from steering diodes 73 and 74, but only if the comparator has also been enabled by signal 82 indicating that an object is being viewed which is derived from signal 59 for the viewing zone IR beam, and only if the output from the respective steering diodes is not zero, thus indicating that a signal derived from signal 71 is being applied.
  • Signals 80 and 81 are fed to comparators 83 and 84.
  • a trip level 85 set by the operator is also fed to comparator 83 which causes the comparator to generate an output signal 88 if signal 80 exceeds the preselected trip level 85.
  • a preset trip level 86 is fed into comparator 84 which causes the comparator 84 to generate an output signal 89 if signal 81 exceeds the preset trip level 86.
  • signal 72 which is responsive to the green beam reflected from the object to be sorted is positive, steering diode 75 allows the positive amplitude of signal 72 to be fed to comparator 90.
  • steering diode 76 allows the negative amplitude of signal 72 to be fed to comparator 91.
  • the green electric signature, signal 92, from the green analog memory 68 is continuously fed to comparators 90 and 91.
  • Comparator 90 generates an output 93 that is indicative of the difference between the green electric signature and the positive amplitude of signal 72.
  • comparator 91 generates a signal 94 that is indicative of the difference between the green electric signature and the negative amplitude of signal 72.
  • Signals 93 and 94 are only generated by comparators 90 and 91 if enabling signal 82 which indicates an object is being viewed is present at comparators 90 and 91, and only if the output from the respective steering diodes is not zero, thus indicating that a signal derived from signal 71 is being applied.
  • Signal 93 is fed into comparator 95 along with trip level 97 set by the operator, and comparator 95 generates an output signal 99 if signal 93 exceeds trip level 97.
  • signal 94 is fed into comparator 96 along with trip level 98 set by the operator, and the comparator 96 generates an output signal 100 if signal 94 exceeds trip level 98.
  • Signal 59 is fed to zero cross detector 101 which generates signal 82.
  • the zero cross detector 101 only generates signal 82 when signal 59 falls below its maximum value indicating that the viewing zone IR beam is being partially blocked by an object being viewed. Thus, signal 82 will only be generated if an object is being viewed.
  • signal 82 is then used to enable comparators 77, 78, 90 and 91.
  • Signals 88, 89, 99 and 100, if generated, are fed to latch gate 102 along with signal 82. If signal 82 and any of signals 88, 89, 99 or 100 are present at latch gate 102, then signal 103 from oscillator 104 is passed by latch gate 102 onto frequency divider 105.
  • the frequency divider 105 is adjustable by the operator for different types of object and typically will be about 50% to 75% of the incoming frequency.
  • the output 106 of the frequency divider 105 is fed to a differentiator 107.
  • the differentiator 107 generates an output 108 for as long as it receives a signal 106 from the frequency divider 105.
  • the signal 108 is stored by the first in, first out (FIFO) storage device 109 for as long as the signal 108 occurs. It should be appreciated that the signal 108 stored by the FIFO 109 is indicative of the length of time that it takes a defective object to traverse the viewing zone. This signal is then used by the FIFO 109 to determine the dwell time that the rejection mechanism is activated for rejecting that defective object.
  • Signal 60 which is proportional to the subviewing zone IR beam, is fed to zero cross detector 110 where it generates a signal 111 which occurs only when signal 60 is below its maximum value indicating that an object has interrupted the subviewing zone IR beam.
  • signal 82 from zero cross detector 101 When signal 82 from zero cross detector 101 is first generated indicating that an object has interrupted the viewing zone IR beam, it activates flip flop circuit 112.
  • the signal 111 from the zero cross detector 110 for the subviewing zone IR beam deactivates the flip flop circuit 112.
  • the flip flop circuit 112 is activated by signal 82 and deactivated by signal 111, it outputs a signal 113 which is fed to gate 114.
  • a signal 115 from the oscillator 104 is constantly fed to gate 114.
  • the gate 114 passes the oscillator signal 115 onto the delay line 116 only when the signal 113 from the flip flop circuit is present.
  • the signal 115 is also fed directly into a binary comparator 117.
  • the delay line 116 gives an output 118 which is fed to the binary comparator 117.
  • the binary comparator 117 gives an output 119, but only when signal 118 has equaled signal 115. This only occurs when the amount of time indicated by signal 115 plus the amount of delay time added by the operator with the delay line 116 has occurred. Therefore, the operator has the ability to delay the output 119 of the binary comparator for as long as desired by adjusting delay line 116.
  • the output 119 of the binary comparator 117 is indicative of the amount of time it will take for the defective object to reach the rejection mechanism, and is used to start the rejection mechanism at the proper time.
  • the output 119 of the binary comparator 117 is also fed back to the binary comparator 117 to reset it so that it is ready to determine the delay time for the next object.
  • the signal 119 from the binary comparator 117 is fed to the FIFO device 109 along with the signal 108 which is representative of the dwell time of the object.
  • the FIFO device 109 acts by starting the rejection mechanism when it receives the signal 119 from the binary comparator 117 and keeps the rejection mechanism activated for as long as indicated by the signal 108.
  • the individual outputs 88, 89, 99 and 100 can also be sent to a FIFO and binary comparator device and this will enable the operator to select the number of pulses per output for individual pulses of the zero cross detector. This enables the operator to select, for example, an object that has only two defects as determined by signal 88 but reject an object with 3 defects from signal 88. It must be appreciated that any combination of number of defects can be selected by the operator based on any or all of the signals 88, 89, 99 and 100.
  • these signals can be processed, stored and compared to an oscillator output acting as a real time clock and the rejection mechanism operated based on length of time individual defects were detected. This gives the operator the ability to accept or reject objects with defects above or below a certain size.
  • the first IR beam 43 is changing from a strong signal to a lesser signal depending on the degree of blockage caused by the size of the object in view.
  • the viewing glass may become covered with a layer of dust and this will decrease the level of IR being detected even when no object is in view. This will adversely affect the gain of the signals 57 and 58.
  • Signal 82 the output of the zero cross detector 101, is used to enable the amplifier and analog memory 120.
  • signal 82 gives the closest signal to maximum possible and thus signifies that no object is in view
  • the "Dirty Glass Adjust” circuit is enabled and the output 66 of the amplifier is allowed to change from the previous setting. No change will occur if the signal strength 59 is the same as the last time it was adjusted.
  • the new signal 66 is then applied to the red and green multipliers 69 and 70 and this new setting effectively overcomes the effect of loss of signal strength caused by dust on the viewing surfaces. It must be appreciated that this adjustment can be up or down depending on whether the glass is cleaner or dirtier than it was at the last adjustment.
  • the strongest IR signal 59 obtained with clean glass is stored in a comparator not shown in Fig. 3 and powered by a stand-by battery.
  • this stored signal is compared with the IR signal 59 detected and if it determines the glass is dirty, the operator is alerted by a commercially available alarm so that the glass can be cleaned before the electric signature procedure is commenced.
  • Signal 113 can be sampled and the frequency generated by flip-flop 112 maintained as a constant by adjusting the feeder circuit (not shown) to maintain a constant flow rate through the viewing zone 2.
  • Signal 82 can be sampled and its amplitude or duration, or both, compared with stored values and the rejection mechanism activated if the sampled values differ from the stored values by more than a predetermined amount.
  • Fig.3 is described as primarily an analog circuit and the preferred method of implementation is to multiplex the signals 57, 58, 59 and 60 and convert them to digital pulses by commercially available analog to digital converters and process all of the signals including the electric signature, ejector dwell and ejector delay, trip settings, dirty glass adjust, number and size of defects, etc. by digital instead of analog technology.
  • the preferred Digital Signal Processor is a Texas Instrument TMS320E15JD but any suitable commercially available item could be used.
  • the gain adjustments 53, 54, 55 and 56 are preferred to be digital to analog converters which may be adjusted both by the operator during initial setting up of the machine and by the processor during operation.
  • all operator adjustments should be performed via panel switches which may be first processed by a microprocessor.
  • the rejection mechanism comprises a commercially available solenoid actuated valve that controls a supply of compressed air.
  • the rejection mechanism 28 is located proximate to the object stream below the viewing head 1 and when activated provides a jet of air which deflects a defective object from the normal path of the object stream.

Landscapes

  • Sorting Of Articles (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Claims (14)

  1. Procédé destiné à distinguer des objets inacceptables qui diffèrent du point de vue taille ou coloration d'objets acceptables, caractérisé par les opérations consistant à :
    a) faire passer un objet acceptable par une zone de visualisation ;
    b) projeter une quantité effective d'une première radiation sur l'objet acceptable lors de son passage à travers la zone de visualisation ;
    c) détecter exclusivement une portion de la première radiation qui a été reflétée par l'objet acceptable, et générer un premier signal électrique uniquement proportionnel à l'intensité de la portion détectée de la première radiation ;
    d) projeter un faisceau de seconde radiation à travers la zone de visualisation de telle sorte que l'objet acceptable bloque une portion du faisceau proportionnel à la taille de l'objet acceptable lorsque l'objet acceptable traverse la zone de visualisation ;
    e) détecter la portion du faisceau non bloqué par l'objet acceptable lorsqu'il traverse la zone de visualisation, et générer un second signal électrique proportionnel à la quantité de faisceau non bloqué par l'objet acceptable ;
    f) mémoriser les premier et second signaux électriques en tant que signature électrique de référence pour les objets acceptables ;
    g) répéter les étapes (a) à (e) pour un objet à trier ;
    h) comparer le premier signal électrique pour l'objet à trier avec le premier signal électrique de la signature électrique pour les objets acceptables, et générer un signal de différence si la différence entre les deux signaux dépasse une valeur présélectionnée ; et
    (i) comparer le second signal électrique pour l'objet à trier avec le second signal électrique de la signature électrique de référence pour les objets acceptables, et générer un signal de différence si la différence entre les deux signaux dépasse une valeur présélectionnée.
  2. Procédé selon la revendication 1, caractérisé de plus par l'opération consistant à projeter un second faisceau de la seconde radiation à travers la zone de visualisation en une position qui est différente du premier faisceau et générer un troisième signal électrique en conséquence de l'interception du second faisceau par un objet traversant la zone de visualisation et traiter les second et troisième signaux électriques pour déterminer la vitesse du mouvement de l'objet dans la zone de visualisation.
  3. Procédé selon la revendication 1 ou 2, caractérisé de plus en ce que
    a) le second signal électrique dérivé du faisceau de la seconde radiation est additionné avec un signal électrique sensiblement équivalent en grandeur au signal électrique produit lorsqu'aucun objet ne se situe dans le faisceau pour dériver un signal de produit ;
    b) le premier signal électrique dérivé de la première radiation réfléchie par un objet dans la zone de visualisation est ajusté par un facteur tel que lorsqu'un objet acceptable de ce type se trouve dans la zone de visualisation, le premier signal électrique sera sensiblement équivalent en grandeur au signal électrique produit de l'étape (a) ;
    (c) le premier signal électrique ajusté provenant de l'étape (b) est additionné avec le signal électrique de produit de l'étape (a) ; et
    (d) le signal électrique additionné produit à l'étape (c) pour un objet à trier est additionné avec un signal électrique de référence correspondant au signal produit à l'étape (c) pour un objet acceptable.
  4. Appareil destiné à trier un objet inacceptable se déplaçant à travers une zone de visualisation (2) dans un courant d'objet, lequel objet diffère par la taille ou la coloration d'un objet acceptable se déplaçant dans le faisceau objet, dans lequel les différences entre les objets acceptables et les objets inacceptables sont détectables par une première radiation appropriée projetée sur les objets dans le faisceau à l'intérieur de la zone de visualisation; caractérisé par
    a) un premier détecteur (45, 46) apte à recevoir exclusivement une portion de la première radiation réfléchie par un objet traversant la zone de visualisation (2) et pour générer un premier signal électrique (57, 58) qui est une fonction de la quantité de la première radiation réfléchie reçue par le détecteur ;
    b) des moyens (67, 68) pour traiter et récupérer le premier signal électrique en tant que première signature électrique (71, 72) pour les objets qui ont été désignés comme étant acceptables ;
    c) une source (27) de seconde radiation qui est différente de la première radiation ;
    d) des moyens pour projeter un faisceau de la seconde radiation à travers la zone de visualisation à bloquer partiellement par chaque objet successif dans le courant d'objet ;
    e) un second détecteur (47) apte à détecter la portion du faisceau de la seconde radiation non bloqué par un objet dans le courant d'objet et pour convertir la seconde portion de radiation détectée en un second signal électrique (82) proportionnel à l'intensité de l'énergie détectée ;
    f) des moyens (120) pour traiter et récupérer le second signal électrique en tant que seconde signature électrique pour les objets qui ont été désignés comme étant acceptables ;
    g) des moyens (77, 78, 90, 91) pour comparer le premier signal électrique pour chaque objet étant trié avec la première signature électrique pour que les objets acceptables génèrent un premier signal électrique de différence (80, 81, 93, 94) réfléchissant une différence entre l'objet qui est en train d'être trié et un objet acceptable ;
    h) des moyens pour comparer le second signal électrique (82) pour chaque objet en cours de tri avec la seconde signature électrique pour que ces objets acceptables génèrent un second signal électrique de différence réfléchissant une différence entre l'objet en cours de tri et un objet acceptable ; et
    i) des moyens (28) sensibles aux niveaux présélectionnés des premier et second signaux électriques de différence pour rejeter les objets dont soit les signaux électriques de différence dépassent la valeur sélectionnée pour ceux-ci.
  5. Appareil selon la revendication 4, dans lequel la première radiation appropriée est la lumière visible.
  6. Appareil selon la revendication 4 ou 5, dans lequel la source (19) de la première radiation appropriée est éloignée de la zone de visualisation d'objet et comprend une fibre optique (11-14) apte à transmettre la lumière à partir de la source éloignée vers la zone de visualisation.
  7. Appareil selon la revendication 4, 5 ou 6, dans lequel le premier détecteur est éloigné de la zone de visualisation et comprend une fibre optique apte à transmettre la portion de la première radiation réfléchie en provenance de la zone de visualisation vers le détecteur.
  8. Appareil selon l'une quelconque des revendications 4 à 7, dans lequel la source (19) de la première radiation appropriée fournit la lumière avec une plage de fréquence et dans lequel l'appareil comprend de plus au moins un filtre dichroïque (25, 26) pour séparer la lumière en une pluralité de faisceaux de plage de fréquence différentes.
  9. Appareil selon l'une quelconque des revendications 4 à 8, comprenant de plus une lentille ou objectif (21, 22) qui possède un foyer infini disposé de telle sorte qu'il reçoit et focalise la première radiation exclusivement réfléchie par les objets traversant la zone de visualisation et transmet cette première radiation réfléchie au premier détecteur.
  10. Appareil selon l'une quelconque des revendications 4 à 9, dans lequel la première radiation se situe dans la région infrarouge (IR) du spectre de radiation.
  11. Appareil selon l'une quelconque des revendications 4 à 10, comprenant de plus une pluralité de fibres optiques (15, 16, 18) pour transmettre la seconde radiation à partir de sa source (27) vers la zone de visualisation et à partir de la zone de visualisation vers le second détecteur.
  12. Appareil selon les revendications 10 et 11, comprenant de plus des faisceaux de fibres optiques bifurqués disposés de telle sorte que chaque faisceau reçoit à la fois la lumière visible et la lumière infrarouge en une extrémité contiguë à la zone de visualisation et transmet à la fois la lumière visible et la lumière infrarouge à une première extrémité bifurquée contiguë au premier détecteur et à une seconde extrémité bifurquée située de façon contiguë à la seconde source de radiation ou au second détecteur de radiation.
  13. Appareil selon la revendication 12, comprenant de plus des faisceaux de fibres optiques bifurqués disposés de telle sorte que chaque faisceau reçoit la lumière visible et projette la lumière infrarouge en une extrémité contiguë à la zone de visualisation et transmet la lumière visible à une première extrémité bifurquée située de façon contiguë au premier détecteur et reçoit la lumière infrarouge à une seconde extrémité bifurquée située de façon contiguë à la seconde source de radiation.
  14. Appareil selon l'une quelconque des revendications 4 à 13, dans lequel le moyen destiné à rejeter les objets est apte à rejeter les objets en différents groupes en fonction de la grandeur des signaux de référence.
EP19890305989 1989-06-13 1989-06-13 Tri optique d'objets Expired - Lifetime EP0402543B1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP19890305989 EP0402543B1 (fr) 1989-06-13 1989-06-13 Tri optique d'objets
DE1989626537 DE68926537T2 (de) 1989-06-13 1989-06-13 Optische Sortierung von Gegenständen

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19890305989 EP0402543B1 (fr) 1989-06-13 1989-06-13 Tri optique d'objets

Publications (2)

Publication Number Publication Date
EP0402543A1 EP0402543A1 (fr) 1990-12-19
EP0402543B1 true EP0402543B1 (fr) 1996-05-22

Family

ID=8202716

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19890305989 Expired - Lifetime EP0402543B1 (fr) 1989-06-13 1989-06-13 Tri optique d'objets

Country Status (2)

Country Link
EP (1) EP0402543B1 (fr)
DE (1) DE68926537T2 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4140513C1 (fr) * 1991-12-09 1993-07-01 Horst 4790 Paderborn De Hager
US5448363A (en) * 1993-08-09 1995-09-05 Hager; Horst Food sorting by reflection of periodically scanned laser beam
US5873470A (en) * 1994-11-02 1999-02-23 Sortex Limited Sorting apparatus
US5538142A (en) * 1994-11-02 1996-07-23 Sortex Limited Sorting apparatus
IT1292445B1 (it) * 1996-08-08 1999-02-08 Truetzschler & Co Procedimento e dispositivo in un impianto per la preparazione alla filatura (tintoria) per il riconoscimento e la separzione di sostanze

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1449519A (en) * 1973-12-13 1976-09-15 Gunssons Sortex Ltd Light-sensitive sorting machine
US4057146A (en) * 1974-05-24 1977-11-08 Xeltron, S.A. Optical sorting apparatus
US4235342A (en) * 1978-05-05 1980-11-25 Geosource Inc. Sorting apparatus using programmable classifier
JPS57151804A (en) * 1981-03-13 1982-09-20 Satake Eng Co Ltd Detecting device for cracked grain of rice
IT1205622B (it) * 1982-12-21 1989-03-23 Illycaffe Spa Procedimento per effettuare una selezione in un materiale granuliforme e macchina per attuare il procedimento
GB2133531B (en) * 1983-01-07 1986-12-17 Delta Technology Corp Agricultural product sorting
IN165987B (fr) * 1985-09-30 1990-02-17 Cra Services

Also Published As

Publication number Publication date
DE68926537T2 (de) 1997-01-16
DE68926537D1 (de) 1996-06-27
EP0402543A1 (fr) 1990-12-19

Similar Documents

Publication Publication Date Title
US5158181A (en) Optical sorter
EP0223446B1 (fr) Appareil de tri optique
EP0060493B1 (fr) Appareil pour détecter des grains de riz crevassés
EP0146299B1 (fr) Machine de tri
EP0719598B1 (fr) Appareil de tri de grains selon la couleur
EP0517950B1 (fr) Dispositif de tri
US4454029A (en) Agricultural product sorting
US5538142A (en) Sorting apparatus
US4281933A (en) Apparatus for sorting fruit according to color
US5873470A (en) Sorting apparatus
CA1079228A (fr) Trieuse a l'infrarouge pour trier les legumes selon leur couleur et eliminer les objets indesirables
US4697709A (en) Sorter for agricultural products
EP0631828B1 (fr) Trieuse selon la couleur pour le tri de légumineuses moisies
KR101060589B1 (ko) 광분배장치를 이용한 실시간 폐플라스틱의 성분 및 색상 선별장치
EP0402543B1 (fr) Tri optique d'objets
US5508512A (en) Sorting machine using dual frequency optical detectors
US5352888A (en) Method and apparatus for detecting and utilizing frame fill information in a sorting machine having a background and a color sorting band of light
US5631460A (en) Sorting machine using dual frequency optical detectors
CA2136779A1 (fr) Methode de tri optique de materiaux en vrac
EP0630693B1 (fr) Machine de tri comprenant un détecteur de format défectueux
US5562214A (en) Process and apparatus for sorting material
US5579921A (en) Optical sorting system for a color sorting machine and process
EP0968772A2 (fr) Une machine de tri
JPH09304182A (ja) 穀粒色彩選別機
GB2133531A (en) Agricultural product sorting

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE ES FR GB GR IT LI LU NL SE

RBV Designated contracting states (corrected)

Designated state(s): DE ES FR GB GR IT

17P Request for examination filed

Effective date: 19910612

17Q First examination report despatched

Effective date: 19930312

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE ES FR GB GR IT

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRE;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.SCRIBED TIME-LIMIT

Effective date: 19960522

Ref country code: FR

Effective date: 19960522

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19960522

Ref country code: ES

Free format text: THE PATENT HAS BEEN ANNULLED BY A DECISION OF A NATIONAL AUTHORITY

Effective date: 19960522

REF Corresponds to:

Ref document number: 68926537

Country of ref document: DE

Date of ref document: 19960627

EN Fr: translation not filed
EN Fr: translation not filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19990610

Year of fee payment: 11

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20000706

Year of fee payment: 12

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20010403

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20010613

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20010613