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WO1990006819A1 - Appareil de triage optique - Google Patents

Appareil de triage optique Download PDF

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Publication number
WO1990006819A1
WO1990006819A1 PCT/GB1989/001489 GB8901489W WO9006819A1 WO 1990006819 A1 WO1990006819 A1 WO 1990006819A1 GB 8901489 W GB8901489 W GB 8901489W WO 9006819 A1 WO9006819 A1 WO 9006819A1
Authority
WO
WIPO (PCT)
Prior art keywords
stream
unacceptable
light
background plate
illuminate
Prior art date
Application number
PCT/GB1989/001489
Other languages
English (en)
Inventor
Michael Cole
Robert John Dennis Wright
Original Assignee
Gbe International Plc
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 Gbe International Plc filed Critical Gbe International Plc
Publication of WO1990006819A1 publication Critical patent/WO1990006819A1/fr

Links

Classifications

    • A—HUMAN NECESSITIES
    • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
    • A24B—MANUFACTURE OR PREPARATION OF TOBACCO FOR SMOKING OR CHEWING; TOBACCO; SNUFF
    • A24B1/00—Preparation of tobacco on the plantation
    • A24B1/04—Sifting, sorting, cleaning or removing impurities from tobacco
    • 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
    • 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
    • B07C5/3422—Sorting according to other particular properties according to optical properties, e.g. colour using video scanning devices, e.g. TV-cameras

Definitions

  • This invention relates to apparatus for detecting unacceptable particles in a stream of particulate material such as tobacco, Kel log's Rice Krispies etc. as described in U.S. Patent No. 3782544.
  • An optical grading system may typically consist of a conveyor feed system by which the material is transported.
  • the material cascades from the feed conveyor to a take-off conveyor.
  • the material as it cascades from one conveyor to the next passes over a reference back plate and is illuminated by a light source.
  • the light source may be a pair of metal halide lamps or a fluorescent lamp operating at a high frequency or by other known methods of illumination.
  • the illuminated material and reference plate are optically scanned by a solid state camera and the video signal processed by an electronic control system.
  • the known optical apparatus may consist of a single line photo-diode array where the number of elements is determined by the resolution required.
  • the scan time or integration time of the camera can be adjusted but for fast response is set at 1 millisecond so that small particles can be detected as they cascade past the scanning area.
  • the video-signal is smoothed and amplified before being fed to a computer circuit which determines when a particle must be rejected.
  • the output from the computer is fed to a logic circuit which activates the appropriate solenoid (from 1 to 64 zones) to reject the particle of material as it transfers to the take-off conveyor.
  • the background plate is used as a reference standard against which the colour of the product is compared.
  • the colour of the reference is used as a divide between the product that is to be accepted and the product to be rejected.
  • the first mode is to reject all material that is darker than the background reference.
  • the acceptable product will transfer to the take-off conveyor and the reject product will be transferred to the reject bin/conveyor.
  • the second mode is to reject all product l ghter than the background reference.
  • An object of the invention is to provide an optical scanning apparatus in which the level of detection of unacceptable material is heightened.
  • a further object is to provide apparatus which can reject material which is lighter, darker or a combination of lighter and darker material compared with a reference background.
  • a further object of the invention is to. provide electronic or optical means to compensate for the non-linear i.e. saucer shape or "smile" characteristic over the field of view of the detector.
  • the optical detector should be most sensitive at wavelengths which maximise the difference between acceptable and reject product material.
  • the use of painted metals or other materials do not have the required specific or repeatable optical characteristics.
  • an apparatus for detecting unacceptable material in a stream of particulate material including means to illuminate the stream of material, scanning detector means arranged to receive light reflected from the particles of material in the stream and to distinguish the level of light reflected from an unacceptable particle from the level from acceptable particles to produce an electrical output signal indicative of the position across the stream of that unacceptable particle, comprising a light reflective background plate disposed behind the stream from the detector means, and means to illuminate that background plate with light in a colour range corresponding to the colour of the acceptable particles of material in the stream.
  • FIGURE 1 is a schematic side view of the grading system
  • FIGURE 2 is a perspective view of the background plate used in the present invention
  • FIGURE 3 shows characteristics of spectral response from acceptable and unacceptable products
  • FIGURE 4 is a characteristic of a video signal having high and low level spikes including rejected material
  • FIGURE 5 is a schematic block diagram of the electric/electronic circuit for controlling rejects means in response to detection of unacceptable material.
  • a conveyor 12 for delivering a stream of tobacco 11 containing unacceptable material such as foil, wrappings, labels, paper and/or string or may be for delivering a cereal product containing the occasional burnt or otherwise objectionable particle.
  • the conveyor 12 is preferably a vibrating inclined conveyor which vibrates the tobacco in a direction as shown by the arrow in FIG. 1.
  • Conveyor 12 ends above another conveyor 13, which can be an ordinary conveyor belt, and is spaced vertically above conveyor 13 a sufficient distance to accommodate the remainder of the apparatus described below.
  • the cascade 14 is illuminated by light source 15 which is preferably a pair of high-temperature lamps 20, such as metal halide or other high-intensity discharge lamps, which emit an increased percentage of their output at the desired spectrum compared to ordinary incandescent lamps.
  • the illuminated area of cascade 14 is scanned by an optical detector 16 having a matrix of electro-optical detectors which is preferably a line-scan camera 21 having a lens 22 and a filter 23.
  • Detector 16 is preferably kept in a housing 24, having an aperture 25 opposite the lens 22 and the filter 23.
  • the scanning area is 1 meter wide by about 1 mm deep and is divided into 64 zones.
  • the camera has a 2048 pixel matrix with a 28mm lens.
  • a background plate assembly 36 Arranged beneath the delivery end of the conveyor 12 and -behind the cascade 14 i.e. remote from the light source 20, there is mounted a background plate assembly 36.
  • the background plate assembly 36 is of a sandwich construction with a clear polycarbonate (e.g. LEXAN, Trade Mark) front 37 which is sandblasted to reduce specular reflection.
  • the middle section 38 is a filter film with fixed optical characteristics to match the product to be treated.
  • the rear background plate 39 is of a flat white material (e.g. PERPLAS, Trade Mark) to give a uniform reflection of all light impinging on it. The light passes through the filter 38 and is reflected back through the filter.
  • the colour of the background plate as seen from the back behind the material by the detector 16 is now the same as or similar to the colour of the product at the chosen wavelength .
  • the filter 38 is thus selected so that the colour of the acceptable product is at a reference level or background colour and therefore undetectable by the optical system 16.
  • the signals detected from unacceptable material can be above or below the reference. There are three options which can be selected; to reject objects darker than the reference, lighter than the reference or a combination of both.
  • the background plate as described enables high and low ampl tude changes to be detected.
  • the video signals with background reference, acceptable product and reject product are represented in Fig. 4.
  • the video signal is fed to control electronics 40 (described in greater detail below) where it is amplified, smoothed and fed to a comparator which is set to reject all material darker, lighter, or with lighter and darker than a desired level .
  • valve 26 is connected at 27 to a source of high pressure fluid which is preferably air at approximately 80 psi , although other gases, such as steam, or liquids, such as water, can be used.
  • a deflection bar 28 is situated below detector 16 adjacent cascade 14. The bar 28 is hollow, and is divided internally into chambers 28 having holes 29 for directing air against cascade 14. Each chamber 28 is supplied by one of the valves 26 through tubes 19.
  • valves 26 When one of valves 26 opens in response to a signal, a blast of air A is directed by the deflection bar 28 against that portion of cascade 14 in which the unacceptable material was detected to force that portion 17 of the tobacco with the unacceptable material to fall into a receptacle 18.
  • the control electronics 40 will " now Pe described:
  • the scanning device 42 is arranged to provide a video signal on the line 70, corresponding to the light intensity reflected from the material in a single line scan across the cascade 14.
  • the scanning device 42 also pzovides a synchronisation pulse on the line 71 to coincide with the commencement of the video signal line on the line 70.
  • the sync pulse is passed to a decoder 72 which embodies a counter arranged to divide the time interval of the video line into a series of elements, in this embodiment 64, to divide the width of the cascade 14 in effect into 64 bands or strips.
  • the counter is started by the sync pulse on line 71.
  • the video signal is passed to an amplifier 73 the gain of which is controlled by control means 74, in dependence from the count from the counter in the decoder 72, indicative of the instantaneous position across the cascade that is represented by that instant in the video signal.
  • the decoder 72 provides an output on the line 75 during the scan time of the video signal on the line 70 to activate a sampl ing means 76 which stores the content of the video signal passed to it from the amplifier 73.
  • An averaging device 77 produces a background compensation signal from averaging the video signal stored in the sample device 76, and a signal representative of the average output of the scanning device 42 is passed to a summing amplifier indicated at 78, together with a pre-set value for a detection threshold which is set on the line 79.
  • the output of the summing amplifier 78, and of the amplifier 73, are passed to a comparator SO, so that when the video signal from the scanning device 42 exceeds a pre-set threshold above the background output, the comparator 80 gives an output signal on the line 81.
  • the outputs 84 are each connected to a respective one of the series parallel shift registers indicated by the block 85. These shift registers are each clocked to carry any input signal along their logical length, in synchronism with the speed of the material; so that an outDut occurs, on one of the series of parallel lines 86, at an instant corresDonding to the arrival of detected unacceDtable matter at the ejection stage.
  • the output lines 86 are connected through driver circuits in the block 87 to the solenoids to control the valves 26, so that the appropriate one is energised to eject the detected unacceptable matter.
  • Pre-set means indicated at 88 may be used to alter the starting point in any of the shift registers of the block 85, to adjust the operation delay of the valves 26 (e.g. 10 to 500 us) when setting up the machine in use.
  • Similar means 89 may be provided for controlling the length of time (e.g. 20-100 ms.) that the valves 26 are operated thus to control the length of air blast during rejection of a particle.
  • the effects of uneven illumination of the individual sensors of the scanning device may be compensated by providing a series of filters between the light source and the cascade, the filters being selected to produce a uniform video signal across the scan width.
  • the filters may be neutral or of wavelengths compatible with the product.
  • the filter of the camera may in this case be omitted.
  • the background plate may take the form of a coating on a substrate or may be a mirror.
  • a single white light source is provided which serves to illuminate both the cascade and the background plate.
  • separate sources may be used to illuminate respectively the cascade material and the background plate.
  • the wavelength extends beyond each end of the visible wavelength i.e. from 0.3 to 1.2 microns but any suitable range may be selected.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Agronomy & Crop Science (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Abstract

Appareil permettant de détecter la présence d'un matériau inacceptable dans un flux de matériau particulaire, qui comprend un dispositif (20) pour éclairer ledit flux de matériau, un dispositif de détection par balayage (16) conçu pour recevoir la lumière réfléchie par les particules du matériau dans le flux, distinguer la qualité de la lumière réfléchie par une particule inacceptable de celle réfléchie par une particule acceptable et produire un signal électrique de sortie qui indique la position de la particule inacceptable dans ledit flux. Derrière le flux, vu depuis le détecteur, se trouve une plaque de fond réfléchissant la lumière (36), qu'éclaire un dispositif (20) avec une lumière ayant une couleur correspondant à la couleur des particules de matériau acceptables dans ledit flux.
PCT/GB1989/001489 1988-12-14 1989-12-13 Appareil de triage optique WO1990006819A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB888829180A GB8829180D0 (en) 1988-12-14 1988-12-14 Optical grading
GB8829180.2 1988-12-14

Publications (1)

Publication Number Publication Date
WO1990006819A1 true WO1990006819A1 (fr) 1990-06-28

Family

ID=10648480

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1989/001489 WO1990006819A1 (fr) 1988-12-14 1989-12-13 Appareil de triage optique

Country Status (2)

Country Link
GB (1) GB8829180D0 (fr)
WO (1) WO1990006819A1 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0517950A1 (fr) * 1991-05-21 1992-12-16 Esm International, Inc. Dispositif de tri
AU698740B1 (en) * 1997-04-22 1998-11-05 Satake Corporation Color-sorting machine for granular materials
EP0865833A3 (fr) * 1997-03-19 1999-02-03 Satake Usa Inc. Arrière-plan réflecteur pour machine de tri
EP1576897A1 (fr) * 2004-03-15 2005-09-21 Universal Leaf Tobacco Company Incorporated Appareil et procédé pour le balayage et le triage de feuilles de tabac
EP1188385A4 (fr) * 1999-06-08 2010-09-15 Japan Tobacco Inc Procede et appareil de detection d'une matiere etrangere dans une matiere premiere
US8281931B2 (en) 2009-09-18 2012-10-09 Key Technology, Inc. Apparatus and method for post-threshing inspection and sorting of tobacco lamina
CN113317548A (zh) * 2021-06-10 2021-08-31 广东中烟工业有限责任公司 一种打叶复烤除杂装置、方法、设备及介质

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3066797A (en) * 1958-10-20 1962-12-04 R W Gunson Seeds Ltd Colour sorting machines
US3782544A (en) * 1972-08-03 1974-01-01 Amf Inc Automatic grader
EP0146299A1 (fr) * 1983-12-06 1985-06-26 Sortex Limited Machine de tri
EP0193308A1 (fr) * 1985-02-25 1986-09-03 Philip Morris Products Inc. Procédé et dispositif pour détecter et enlever des matériaux étrangers d'un courant de matière particulaire
US4634881A (en) * 1982-11-09 1987-01-06 Supernova Systems, Inc. Apparatus for detecting impurities in translucent bodies
GB2180062A (en) * 1985-09-03 1987-03-18 Delta Technology Corp Sorter for agricultural products

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3066797A (en) * 1958-10-20 1962-12-04 R W Gunson Seeds Ltd Colour sorting machines
US3782544A (en) * 1972-08-03 1974-01-01 Amf Inc Automatic grader
US4634881A (en) * 1982-11-09 1987-01-06 Supernova Systems, Inc. Apparatus for detecting impurities in translucent bodies
EP0146299A1 (fr) * 1983-12-06 1985-06-26 Sortex Limited Machine de tri
EP0193308A1 (fr) * 1985-02-25 1986-09-03 Philip Morris Products Inc. Procédé et dispositif pour détecter et enlever des matériaux étrangers d'un courant de matière particulaire
GB2180062A (en) * 1985-09-03 1987-03-18 Delta Technology Corp Sorter for agricultural products

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0517950A1 (fr) * 1991-05-21 1992-12-16 Esm International, Inc. Dispositif de tri
US5265732A (en) * 1991-05-21 1993-11-30 Esm International, Inc. Variable background for a sorting machine
EP0865833A3 (fr) * 1997-03-19 1999-02-03 Satake Usa Inc. Arrière-plan réflecteur pour machine de tri
AU698740B1 (en) * 1997-04-22 1998-11-05 Satake Corporation Color-sorting machine for granular materials
EP1188385A4 (fr) * 1999-06-08 2010-09-15 Japan Tobacco Inc Procede et appareil de detection d'une matiere etrangere dans une matiere premiere
EP1576897A1 (fr) * 2004-03-15 2005-09-21 Universal Leaf Tobacco Company Incorporated Appareil et procédé pour le balayage et le triage de feuilles de tabac
US7383840B2 (en) 2004-03-15 2008-06-10 Universal Leaf Tobacco Company, Inc. Apparatus for scanning and sorting tobacco leaves
US8281931B2 (en) 2009-09-18 2012-10-09 Key Technology, Inc. Apparatus and method for post-threshing inspection and sorting of tobacco lamina
CN113317548A (zh) * 2021-06-10 2021-08-31 广东中烟工业有限责任公司 一种打叶复烤除杂装置、方法、设备及介质
CN113317548B (zh) * 2021-06-10 2022-09-13 广东中烟工业有限责任公司 一种打叶复烤除杂装置、方法、设备及介质

Also Published As

Publication number Publication date
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