EP1214581A1 - Dispositif et procede de detection de corps etrangers dans des produits - Google Patents

Dispositif et procede de detection de corps etrangers dans des produits

Info

Publication number
EP1214581A1
EP1214581A1 EP00964859A EP00964859A EP1214581A1 EP 1214581 A1 EP1214581 A1 EP 1214581A1 EP 00964859 A EP00964859 A EP 00964859A EP 00964859 A EP00964859 A EP 00964859A EP 1214581 A1 EP1214581 A1 EP 1214581A1
Authority
EP
European Patent Office
Prior art keywords
product
detection
signals
signal
amplitude
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.)
Withdrawn
Application number
EP00964859A
Other languages
German (de)
English (en)
Inventor
Harald Merkel
Mikael Reimers
Christina SKJÖLDEBRAND
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.)
FOOD RADAR SYSTEMS IN SWEDEN AB
Original Assignee
Sik - Institut For Livsmedel Och Bioteknik AB
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
Priority claimed from SE9903348A external-priority patent/SE517315C2/sv
Application filed by Sik - Institut For Livsmedel Och Bioteknik AB filed Critical Sik - Institut For Livsmedel Och Bioteknik AB
Publication of EP1214581A1 publication Critical patent/EP1214581A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/02—Food

Definitions

  • the present invention relates to an apparatus for detection of foreign bodies m products, especially m food products, according to claim 1.
  • the invention also relates to a method using said apparatus.
  • the present invention relates to an apparatus for detection of changes m material properties and contents m a product, especially detection of voids, defects and mhomo- geneities within a material, according to claim 16.
  • the invention also relates to a method using said apparatus.
  • foreign bodies comprises all solid materials that are undesired m food products, originating from the product or not, such as bone fragments, bits of glass, rubber, grovel/stone, hair, insects, etc.
  • Present techniques to detect some classes of foreign oodies m food products are very expensive and/or can only detect some foreign bodies, such as magnetic bodies, bodies with deviating colour and size or bodies with deviating weight. Examples of such techniques are ocular examination and X-ray detection.
  • a detection method of metal in foodstuff is disclosed.
  • the purpose of the invention is to detect metal powder, irrespective of the shape and size of the foodstuff by irradiating metal contaminated foodstuff with microwaves m order to generate an electric discharge, which discharge is detected.
  • an apparatus for determining the qualities of an irradiatable body by means of penetrating radiation where said radiation could be of any wavelength.
  • the apparatus comprises a device for parallel radiation from one side of a irradiable body, a device for receiving the radiation leaving the body and deriving a transmission signal therefrom, and means for deriving from the transmission signal information concerning the qualities of the irradiated body, such as bone tissue m pieces of meat .
  • the mass of the inspected body is determined, the mass of the body is a function of height and density and a correlation exists between mass and radiation attenuation, thus a presence of possible mhomogeneities may be detected.
  • a problem encountered with the prior art is that it is impossible, or very difficult, to detect a multitude of different types of foreign bodies m products. Metal or particles with high density are easy to detect m a product containing material with low density, but foreign bodies embedded m a material with a similar density are difficult to detect .
  • a further problem with present techniques is that it is difficult to achieve on-line detection of foreign bodies on a completed product m production, which means that the detecting method has to be fast, non- invasive and nondestructive .
  • a first object with the invention is to provide an apparatus and a method for detection of foreign bodies in products, especially food products, which overcome the above mentioned problems .
  • the first object is achieved by an apparatus according to claim 1.
  • a second object with the invention is to provide an apparatus and a method for detection of changes in material property and content in materials.
  • the second object is achieved by an apparatus according to claim 16.
  • An advantage with the present invention is that a large variety of foreign bodies is detectable in a product.
  • Another advantage is that the present invention allows fast measurement, detection and evaluation.
  • Still another advantage is that the present invention is cheap and easy to implement and can be integrated in existing production facilities. Still another advantage is that the present invention allows to detect foreign bodies in products after final processing, in a non-destructive manner.
  • the invention provides an apparatus and a method for detecting deviation of the material properties and contents of a product, or material, provided that the product comprises two components having different dielectric constants.
  • Fig. 1 shows an apparatus according to the present invention.
  • Fig. 2 shows an antenna device, which may be used in the apparatus in Fig. 1.
  • Fig. 3 shows a side view of an antenna arrangement according to the present invention.
  • Fig. 4 shows a side view of an antenna arrangement, as in figure 2, illustrating diffraction/scattering in an examined product .
  • Fig. 5a-5c shows a method to extract information regarding diffraction measurements, according to the present invention.
  • Figure 1 shows an apparatus 10 for detection of foreign bodies in a product 1 according to the present invention.
  • the inventive apparatus comprises a first antenna device 11, a second antenna device 12, where said first antenna device 11 transmits electromagnetic signals 13' in the microwave range.
  • the transmitted signals 13' are arranged to, at least partially, pass through the product 1, which is under examination. After the signals have passed through the material 1 the signals 13" are received at said second antenna device 12.
  • the first and second antenna device 11, 12 transmits and receives signals having at least two separate frequencies, preferably more, e.g. 400, different separate frequencies in several contiguous frequency blocks furthermore referred to as frequency channels.
  • the antenna devices which are described in more detail in figure 2, are connected to a microwave circuit 14, such as a network analyser.
  • the microwave circuit 14 comprises a microwave oscillator 15, which feeds signals 13' to be transmitted to the first antenna device 11, and a microwave measuring system 16, e.g. a vector voltmeter, which collects and measure certain parameters, such as amplitude [Al and/or phase ⁇ , of the received signals 13" from the second antenna device 12.
  • the product 1 which is under examination is preferably placed on a transportation system 17 comprising, for instance, a carrier 18 on a conveying equipment 19, a conveyor belt, a vertical pipe with flowing products or the like.
  • the products pass through a gap between the first 11 and the second 12 antenna device, to allow the transmitted signals to, at least partially, pass through the whole of said product.
  • the product 1, which is placed on the carrier 18, is moved through the open space by means of, for instance, a motor driven cart.
  • Signals having pre-selected number of frequencies in the microwave range, in one or more frequency channels, are transmitted from said first antenna device, and are received at said second antenna device to be measured in the network analyser 14.
  • a new measurement is performed after a predetermined time interval, during which the product has moved a distance in a first direction x.
  • the antenna devices comprise at least one frequency channel within which channel at least two separate frequencies may be transmitted. This may be implemented using a separate antenna , or antenna section, for each frequency channel, where the frequency of each transmitted signal within each frequency channel may be controlled by the microwave oscillator 15.
  • a preferred embodiment of a first antenna device 11 is shown in figure 2, which transmits signals in a plurality of frequency channels, f ⁇ -f 6 .
  • This type of antenna is a patch antenna with capacitively coupled patches.
  • the mid frequency for each frequency channel could be as presented in table 1.
  • the second antenna device 12 comprises the same features as the first antenna device 11 for reception of the transmitted signals.
  • Table 1 A schematic layout of the wave pattern of the centre frequencies is illustrated in figure 2 as dashed lines wi th reference to the different channels f 2 -f 6 in table 1 .
  • the basic theory behind the invention is to detect differences, such as foreign bodies, contamination, damages (cracks etc.), causing a change in the dielectric constant of the examined product. This is done by transmitting signals, at least partially, through said product, which in it self must, at least partially, consist of a dielectric substance.
  • Parameter values from said parameters such as amplitude
  • the measured parameter values are compared with the corresponding values of the transmitted signals, so as to obtain a comparison value for each frequency in each frequency channel .
  • Each comparison value is then compared with a reference value, which is available to the microwave circuit 14, e.g. stored in a memory 20 in said microwave circuit 14.
  • Reference values are preferably obtained by measuring parameters from received signals that have passed through a reference sample of the examined type of product, which reference sample is free from any foreign bodies or other defects that will cause a change of the properties of the microwave transmission through the product as described by the profile of the dielectric function as a function of frequency.
  • the reference values are preferably obtained by measuring parameter values of a plurality of products, and calculate statistics, such as an average, for each parameter value and use that as a reference value for each frequency.
  • a typical number of products, measured to obtain said calculated reference value, is approximately 100 products.
  • reference values may be obtained evaluating a model for the microwave transmission through the product and the transmit and receive properties of the antennas 11 and 12.
  • Figure 3 shows a side view of the measurement gap where the examined product 1 passes through.
  • the first antenna device 11 On the left side of the product is the first antenna device 11 arranged and on the right side is the second antenna device 12 arranged.
  • a signal 30 is transmitted from said first antenna device 11, and received by said second antenna device 12.
  • phase ⁇ is proportional to:
  • z is the distance between the first and the second antenna device 11, 12
  • k z is the propagation constant m the z direction
  • n is an integer number and stands for the number of completed trains m the gap.
  • the propagation constant is m turn equal to:
  • FIG 3 there is shown a first transmitted signal 30, drawn with a continuous line, having two complete oscillation periods 31, 32, preceding the last not complete period 33.
  • a second signal 34 drawn with a dashed line, a different frequency compared to the first signal 30, having two complete oscillation periods 35, 36, preceding the last not complete period 37, the propagation time may be determined by plotting the equivalent dielectric function assuming different number of oscillation periods, as is shown figure 4.
  • the equivalent dielectric function is unknown, but may be expressed as a known part, ⁇ prodU ct ( ⁇ , ⁇ ) , belonging to the clean product and an unknown part, ⁇ fore ⁇ gn ody ( ⁇ ⁇ ) belonging to the microwave transmission properties of the foreign body.
  • the equivalent dielectric function of the foreign body contains scattering, diffraction, absorption, reflection and transmission effects of the foreign bodies. Therefore it depends strongly on frequency ⁇ (since diffraction lobes shift with frequency) and with the angle of observation ⁇ (if sharp edges are present) .
  • FIG. 4 illustrates what happens when a signal 13' is transmitted from said first antenna device 11, through a product 1. Inside said product, there is a small piece of a foreign body 60, such as metal, stone, etc., disturbing the signal on its way to the receiving antenna device 12.
  • the received signal 13" will in this case be subject to diffraction or scattering causing an interference pattern to arise. This will mainly be detectable as a characteristic pattern in the amplitude
  • the main task of the signal processing part is the appropriate filtering of the data and the definition of a threshold value enabling to discern contaminated from non-contaminated products minimising the estimator errors in both directions, i.e. (1) assigning a foreign body to a pure product and (2) letting a contaminated product pass. Obviously some tolerances at (1) is given whereas (2) must be reduced as far as possible. For simple classes of products and foreign bodies (i.e. homogenous, wet products and dry foreign bodies) it is sufficient to apply equation (I) directly and replace the equivalent dielectric function of the pure product by measured data from a pure product and calculating the difference between the measured reference and measured product. If the mean square of the residual does not exceed a certain threshold, the product is considered ok, otherwise it is rejected.
  • equation (I) directly and replace the equivalent dielectric function of the pure product by measured data from a pure product and calculating the difference between the measured reference and measured product. If the mean square of the residual does not exceed a certain threshold, the product is considered ok, otherwise it is rejected.
  • Figure 5a-5c illustrates how a useful value may be obtained using especially the information contained in the diffraction patterns.
  • FFT Fast Fourier Transform
  • Figure 5c shows the resulting curve 73 after a retransformation of the filtered FFT-spectrum in figure 5b back to the damping I S 2 ⁇ l(x ⁇ ) as a function of frequency f.
  • a threshold value 74 is also indicated, where values lower than the threshold value for each frequency is allowed, and, accordingly, values higher than the threshold is unacceptable and renders an alarm signal from the microwave circuit 14, where the FFT treatment is performed.
  • the above described apparatus and method for detecting foreign bodies in material may also be used within the area of monitoring and detecting changes in material property and content, provided said material comprises at least two different components having different dielectric constants.
  • An example of such a material is a material having a void within the material, such as a plastic part having an air bubble inside.

Landscapes

  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Geophysics And Detection Of Objects (AREA)

Abstract

La présente invention concerne un dispositif de détection de corps étrangers ou de changements des propriétés et du contenu d'un produit, comprenant une première antenne servant à émettre des signaux électromagnétiques dans la gamme des micro-ondes, lesquels signaux comprennent au moins deux signaux de fréquences différentes, une seconde antenne destinée à recevoir les signaux provenant de la première antenne, les signaux reçus traversant au moins partiellement ledit produit, des éléments mesurant au moins l'amplitude et la phase desdits signaux reçus pour chaque fréquence séparément afin d'obtenir des valeurs de paramètre, des éléments de comparaison desdites valeurs avec l'amplitude et la phase correspondantes des signaux émis afin d'obtenir une valeur de comparaison pour chacune desdites fréquences, des éléments d'analyse de chaque valeur de comparaison en fonction d'une valeur de référence accessible audit dispositif, et des éléments d'émission d'un signal lorsque la différence entre la valeur de comparaison et la valeur de référence est supérieure à une quantité déterminée. L'invention concerne également un procédé de détection de corps étrangers dans des produits. L'invention concerne en outre un procédé d'utilisation dudit dispositif.
EP00964859A 1999-09-17 2000-09-14 Dispositif et procede de detection de corps etrangers dans des produits Withdrawn EP1214581A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
SE9903348 1999-09-17
SE9903348A SE517315C2 (sv) 1999-09-17 1999-09-17 Apparat och metod för detektering av främmande kroppar i produkter
US506832 2000-02-18
US09/506,832 US6456093B1 (en) 1999-09-17 2000-02-18 Apparatus and method for detection of foreign bodies in products
PCT/SE2000/001783 WO2001020311A1 (fr) 1999-09-17 2000-09-14 Dispositif et procede de detection de corps etrangers dans des produits

Publications (1)

Publication Number Publication Date
EP1214581A1 true EP1214581A1 (fr) 2002-06-19

Family

ID=26663649

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00964859A Withdrawn EP1214581A1 (fr) 1999-09-17 2000-09-14 Dispositif et procede de detection de corps etrangers dans des produits

Country Status (4)

Country Link
EP (1) EP1214581A1 (fr)
AU (1) AU770854B2 (fr)
CA (1) CA2384831C (fr)
WO (1) WO2001020311A1 (fr)

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10100664A1 (de) 2001-01-09 2002-07-11 Hauni Maschinenbau Ag Verfahren zum Prüfen eines Produktionsmaterials
EP1853900A1 (fr) * 2005-02-18 2007-11-14 Food Radar System in Sweden AB Systeme et procede de detection de corps etrangers dans un produit
CN102621161B (zh) * 2012-03-31 2013-10-16 中国科学院长春应用化学研究所 一种材料性能参数获取方法
EP3598113B1 (fr) * 2017-03-17 2022-06-22 National Institute of Advanced Industrial Science and Technology Procédé de détection non destructif, dispositifs de détection non destructif et programme de détection non destructif
CN110161057B (zh) * 2019-05-09 2023-07-25 浙江浙能数字科技有限公司 一种基于微波收发器的输煤皮带上异物的检测装置及方法
CN111896559B (zh) * 2020-08-21 2022-11-25 爱德森（厦门）电子有限公司 一种隐形材料性能衰变点频式检测方法及其系统装置
CN116106334B (zh) * 2023-04-13 2023-06-09 中国民航大学 基于rfid的物品含水率无损检测方法

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SE449138B (sv) * 1984-06-27 1987-04-06 Stiftelsen Inst Mikrovags Forfarande jemte anordning for bestemning av mikrovagors dempning och/eller fasvridning vid transmission genom ett material
DE3531893A1 (de) * 1985-09-06 1987-03-19 Siemens Ag Verfahren zur bestimmung der verteilung der dielektrizitaetskonstanten in einem untersuchungskoerper sowie messanordnung zur durchfuehrung des verfahrens
DE3723606A1 (de) * 1987-07-17 1989-01-26 Kernforschungsz Karlsruhe Verfahren und vorrichtung zur analyse mittels mikrowellen
GB9122210D0 (en) * 1991-10-18 1991-11-27 Marconi Gec Ltd Method for measurement of the gas and water content in oil
JP3139874B2 (ja) * 1993-03-30 2001-03-05 株式会社東芝 濃度計
DE4311103A1 (de) * 1993-04-05 1994-10-06 Komi Koppelberg & Migl Kg Verfahren und Vorrichtung zum Erkennen von Fehlern bei Glaskörpern
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US5886534A (en) * 1995-10-27 1999-03-23 The University Of Chicago Millimeter wave sensor for on-line inspection of thin sheet dielectrics
SE512315C2 (sv) * 1997-01-17 2000-02-28 Lars Baaaath Sätt att med radiovågsteknik kartlägga inhomogeniteter i trä
EP1017996B1 (fr) * 1997-09-25 2008-05-28 Jack R.. Little, Jr. Inspection non destructive de materiaux dielectriques
DE29719600U1 (de) * 1997-11-05 1998-01-02 RGI Industriemeßgeräte GmbH, 75323 Bad Wildbad Vorrichtung zur Erfassung von Inhomogenitäten, insbesondere von Fremdkörpern, in einer zu kontrollierenden Materialienschicht
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Also Published As

Publication number Publication date
CA2384831A1 (fr) 2001-03-22
AU770854B2 (en) 2004-03-04
AU7568000A (en) 2001-04-17
CA2384831C (fr) 2009-05-19
WO2001020311A1 (fr) 2001-03-22

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