EP0965021B1 - Installation for the treatment of food items - Google Patents

Installation for the treatment of food items Download PDF

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Publication number
EP0965021B1
EP0965021B1 EP98909553A EP98909553A EP0965021B1 EP 0965021 B1 EP0965021 B1 EP 0965021B1 EP 98909553 A EP98909553 A EP 98909553A EP 98909553 A EP98909553 A EP 98909553A EP 0965021 B1 EP0965021 B1 EP 0965021B1
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EP
European Patent Office
Prior art keywords
conveyor
products
image
camera
articles
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
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EP98909553A
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German (de)
French (fr)
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EP0965021A1 (en
Inventor
Bernard Delpuech
Nicolas Viard
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.)
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
Air Liquide SA
LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude
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Application filed by Air Liquide SA, LAir Liquide SA a Directoire et Conseil de Surveillance pour lEtude et lExploitation des Procedes Georges Claude filed Critical Air Liquide SA
Publication of EP0965021A1 publication Critical patent/EP0965021A1/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D3/00—Devices using other cold materials; Devices using cold-storage bodies
    • F25D3/10—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air
    • F25D3/11—Devices using other cold materials; Devices using cold-storage bodies using liquefied gases, e.g. liquid air with conveyors carrying articles to be cooled through the cooling space
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06M—COUNTING MECHANISMS; COUNTING OF OBJECTS NOT OTHERWISE PROVIDED FOR
    • G06M7/00—Counting of objects carried by a conveyor
    • G06M7/02—Counting of objects carried by a conveyor wherein objects ahead of the sensing element are separated to produce a distinct gap between successive objects
    • G06M7/04—Counting of piece goods, e.g. of boxes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D2500/00—Problems to be solved
    • F25D2500/04—Calculation of parameters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D2700/00—Means for sensing or measuring; Sensors therefor
    • F25D2700/16—Sensors measuring the temperature of products

Definitions

  • the present invention relates to an installation of article processing as defined in the preamble to the claim 1.
  • Such an installation is, for example, known from document EP-A-0 167 405.
  • the invention relates to food processing facilities, for example example of installations freezing of food items, such as portions minced meat or fish fillets, dishes prepared, dairy products, or pastries. It will be understood that the list given previously cannot be considered as limiting but is in fact purely illustrative of the many possibilities of the food industry.
  • Known deep freezing systems include for example a deep freezing tunnel leaves by a belt conveyor on which the items to be frozen.
  • the belt conveyor runs in continuous through the freezing tunnel.
  • the freezing tunnel is supplied with a fluid cryogenic, such as liquid nitrogen or dioxide liquid carbon.
  • a fluid cryogenic such as liquid nitrogen or dioxide liquid carbon.
  • This cryogenic fluid is brought into contact with the articles to be treated. In contact with the articles, the cryogenic fluid vaporizes, thereby transferring frigories to articles.
  • These scales generally include a conveyor belt placed upstream of the belt conveyor of the tunnel freezing. Weighing devices are arranged below of the conveyor in order to continuously determine the weight of articles circulating on this one. In the event that several items, for example portions of minced meat, are arranged side by side across the width of the conveyor, several weighing devices are arranged side by side following the movement paths of the articles.
  • the weighing devices used in the means of detection currently known include moving parts and implement a weighing mechanism sophisticated. This mechanism is sensitive to the influence of temperature. In particular, the weighing devices are prone to freezing blockages when put on used at a very low temperature.
  • the weighing devices cannot be directly associated with the conveyor of the freezing tunnel.
  • the invention aims to provide a solution to disadvantages mentioned above and in particular of provide an item processing facility ensuring detection of articles processed by the device directly on the conveyor associated with the device and which either insensitive to the influence of temperature, but also allowing the determination of the actual temperature of outgoing items installation.
  • the subject of the invention is a installation as defined in claim 1.
  • the camera associated with the means of image processing determines a value representative of the quantity and, where appropriate, the quality of the articles introduced into the device, for example the number of items or their volume, or the rate occupancy of the conveyor, without using any means mechanical sensitive to the effects of temperature.
  • the image being taken directly on the conveyor transfer of the treatment device the installation is small footprint and requires no transfer between characterization means and the apparatus of actual treatment.
  • the installation shown in Figures 1 and 2 has a freezing tunnel 10 open to both ends. It includes a supply line 11 in cryogenic fluid, for example liquid nitrogen.
  • the tunnel is traversed by a conveyor belt 12 circulating in the direction X-X in the direction of the arrow F1.
  • the conveyor protrudes from each side of the tunnel freezing 10.
  • it includes a section input 14 for the entry into the tunnel of articles to be frozen and an outlet section 16 for the evacuation of frozen items.
  • the tunnel shown is assumed to be suitable for freezing portions of roughly shaped meat oval. These portions are designated by the letter P in the figures.
  • the inlet section 14 of the conveyor is arranged in output of a machine M for shaping the portions.
  • This machine is suitable for producing simultaneously from one to six servings of minced meat.
  • Transfer means not shown are provided to take the portions out of the machine formatting M and depositing these on the section input 14.
  • the means of transfer are adapted to deposit the portions P sequentially on the conveyor circulating continuously according to a predefined pattern.
  • the portions P are arranged in lines along the width Y-Y of the conveyor 12, as shown in Figure 1.
  • the portions P are aligned in rows which may include a to six servings, depending on the number of servings simultaneously produced by the shaping device Mr.
  • the installation comprises means 20 for detecting the articles treated in the tunnel.
  • These means 20 here comprise a camera 22 connected to a information processing unit 23.
  • the latter comprises a central computing unit 24 comprising in particular means for processing a digital image collected by said camera.
  • the camera 22 is arranged above the inlet section 14 of the conveyor with its shooting direction extending substantially perpendicular to the plane of movement of the conveyor 12.
  • the camera is for the embodiment shown suitable for taking a digital image monochrome covering most of the section surface 14.
  • FIG. 3 An example of image collected by the camera 22 is shown in Figure 3.
  • This image, designated by the reference 25, shows two rows, noted R1, R2, each with five black spots corresponding to conveyor areas covered by an article Surface of the conveyor left free appears in white on the image 25.
  • the means 24 for processing the digital image are suitable for determining a representative value of the quantity of articles treated by the tunnel.
  • This quantity is for example the number n of articles introduced, the volume of articles introduced, or the rate occupancy of the conveyor.
  • the central computing unit 24 is for example formed by a microcomputer comprising an interface connection to camera 22 suitable for collecting an image digitized.
  • An image processing program is loaded in the microcomputer in order to analyze the image produced by said camera. This will be described later in reference to figure 4.
  • the information processing unit 23 comprises means for triggering the taking of an image at a predetermined frequency (i.e. transfer of a image from camera to unit), frequency which is includes will depend on the type of treatment then performed by the unit, frequency therefore sufficiently low to allow computer image processing.
  • This frequency is for example of the order of 0.3 Hertz but may commonly vary between a few tenths of Hertz and a few tens Hertz.
  • the installation shown on the Figure 1 includes an optical barrier 26 comprising two sections of optical fiber 28, 30 aligned, the opposite ends 28A, 30A are arranged face to face with on either side of the conveyor 12.
  • the embodiment illustrated here is therefore based on the combined use of a monochrome camera and a optical barrier.
  • the section 28 of optical fiber has at its other end a light emitting diode 32 powered by a source of electrical power for the establishment of a permanent light beam through of fiber 28.
  • the other end of fiber 30 is associated with a photodetector 34 connected to the central processing unit calculus 24.
  • Fibers 28 and 30 are arranged at a level such as the light beam passing through the conveyor in the direction Y-Y and extending from the fiber 28 to fiber 30 is interrupted by rows of items traveling on the conveyor.
  • the photodetector 34 connected to the unit 23, allows thus to determine the number of beam interruptions, which corresponds to the number of rows of penetrating items in the freezing tunnel 10. If the items are arranged in a different pattern in a row, by example an arc of a circle, the optical barrier 26 exerts identical function of counting the number of patterns entering the tunnel, regardless of number of items in each pattern.
  • nozzles 36, 38 are provided for ejecting a gas dry, especially nitrogen, on the ends of the fibers optics to protect them from the effects cold.
  • nozzles are connected to supply means as dry gas, this gas being at a temperature higher than the temperature prevailing in the tunnel enclosure.
  • the temperature of the dry gas ejected is for example equal to the room temperature (20 ° C).
  • the central computing unit 24 is connected to a flow meter 40 suitable for determining the fluid flow cryogenic introduced into tunnel 10.
  • the unit 24 is connected to storage means 42 comprising, for each type of article which can be treated in the tunnel, a curve G 5 , specific to the article, of variation of its enthalpy as a function of its temperature.
  • a display screen 44 is connected to the unit data center 24 in order to display the temperature of the items leaving the tunnel.
  • the installation according to the invention operates from the next way.
  • the camera 22 While the articles circulate continuously on the conveyor, the camera 22 detects at a given frequency a image of section 14 and transmits it to the information processing 23. It is then analyzed by the image processing program.
  • the image processing program implemented includes a first step of filtering the image from the camera.
  • This first step designated by The reference 50 on the flow diagram of FIG. 4, consists in comparing the gray level of each pixel of the image to a value of reference and to replace the pixel considered by a pixel white if the gray level is less than the value of reference and with a black pixel if the gray level is greater than the reference value. So it results an image like the one shown in Figure 3 in which areas of the conveyor covered by an article form black spots on a white background.
  • the image is positioned so that the direction X-X of advancement of the conveyor extends according to the height of the image and that the width Y-Y of the conveyor, direction perpendicular to the direction of travel of the conveyor expands along the width of the image.
  • step 52 the program establishes a histogram 52A of the number of black pixels in the X-X direction. This histogram represents, for each line parallel to the axis Y-Y of the scanned image, the total number of black pixels contained in this line. The calculation is made for all the lines of the image.
  • the histogram 52A has two successive peaks corresponding to the two rows R1 and R2.
  • a histogram 54A is established in step 54 by summing the black pixels for each line of the scanned image parallel to the X-X axis. As shown in Figure 3, the histogram 54A has five peaks corresponding to the five articles contained in the two rows R1 and R2.
  • steps 56 and 58 the program determines the number of peaks contained in histograms 52A and 54A.
  • the program counts for example, for each histogram, the number of peaks including the height exceeds a predetermined reference value S1, S2 represented by a dotted line in Figure 3.
  • the program calculates, in step 60, the number of items shown in the image and in especially the number of items per row. This last value is indicative of the density of items on the conveyor at the instant considered.
  • the central computing unit 24 connected to the barrier optics 26 allows continuous determination with precision the number of rows of items processed through the tunnel.
  • unit data center 24 continuously determines the number of articles brought inside the tunnel.
  • the program determines, in step 60, the dimensions of the articles in both directions extending perpendicular to the grip direction camera view.
  • the program determines the occupancy rate of the conveyor, i.e. the the surface occupied by the articles to be treated on the surface free of the conveyor contained in the analyzed image.
  • the occupancy rate of the conveyor constitutes a other value representative of the density of articles on the conveyor.
  • the central computing unit 24 continuously determines from the oc rate: collection of conveyor and the actual number of rows of items penetrating in the tunnel, a value representative of the quantity items entering the tunnel at any given time. This value is for example the product of the rate occupancy by the number of rows entering the tunnel per unit of time.
  • camera 22 does not provide an image of all items entering the tunnel, due to speed high conveyor circulation and slowness relative to the calculation unit, it is possible by the combined use of the camera and the barrier optics to accurately determine a representative value the quantity of articles treated in the installation.
  • the central computing unit 24 includes a program making it possible to continuously determine this temperature from a stored curve G 5 of enthalpy variation, of the volume q of cryogenic fluid introduced into the tunnel per unit of time, the pressure and temperature of the cryogenic fluid, as well as the number n of articles, the mass of which is known, introduced per unit of time into the tunnel and their temperature input Te.
  • the cryogenic fluid is liquid nitrogen. It could be replaced by carbon dioxide, argon or any other fluid.
  • the curve G 5 translates the variation of the enthalpy H of a kilogram of articles when the temperature thereof changes from the temperature of -189 ° C (temperature of liquid nitrogen to the storage pressure for example equal to 2 bars absolute) at any temperature T given on the abscissa and at atmospheric pressure.
  • the enthalpy curve G 5 stored in the storage means 42, is determined experimentally.
  • a kilogram of articles is immersed in a known initial temperature T in a container of Dewar filled with liquid nitrogen and we measure, for example at using a balance, the amount of nitrogen vaporized to bring items from initial temperature to liquid nitrogen temperature (-196 ° C) at pressure atmospheric.
  • the enthalpy H transferred to articles in the Dewar container corresponds to the enthalpy of vaporization nitrogen at the pressure considered. This value is proportional to the measured amount of vaporized nitrogen.
  • the program loaded into the central computing unit 24 continuously determines the final temperature Ts of a kilogram of articles leaving the tunnel, from the inlet temperature Te and the enthalpy DH T transferred to a kilogram of articles by the nitrogen introduced into the tunnel.
  • the program finally determines the temperature Ts of the articles leaving, this temperature corresponding to the enthalpy Hs.
  • the central computing unit 24 is connected to a temperature probe brought into contact with items immediately before entering the tunnel. It can also be the temperature of a stabilization in which the items have stayed before their introduction into the tunnel.
  • the enthalpy DH T transferred by nitrogen to the articles in the tunnel is determined as follows.
  • the curve G 6 gives the enthalpy DH released by a liter of liquid nitrogen when the latter passes, for a given pressure, from its liquefaction temperature to any temperature T given on the abscissa.
  • the program determines from curve G 6 the enthalpy DH Ta released in the tunnel by a liter of liquid nitrogen, when this vaporizes and passes from its storage temperature (- 189 ° C) at the temperature Ta of the gases leaving the tunnel.
  • the temperature Ta is for example measured inside from the tunnel enclosure to its exit (for example at 1 meter before the gas outlet) by a temperature probe connected to the central computing unit 24.
  • This temperature Ta is generally related to the temperature of setpoint of the tunnel and the entry temperature of the articles. It is for example of the order of -30 ° C.
  • the mass M P of articles introduced into the tunnel per unit of time is determined from the number n of articles detected at the entrance to the tunnel per unit of time and the average weight of the articles.
  • the enthalpy DH T is then calculated from the gross enthalpy DH B taking into account the thermal losses of the tunnel DH P.
  • the material enthalpy losses DH P of the tunnel are evaluated experimentally by leaving the tunnel to operate in the absence of articles for different temperature values T prevailing inside the enclosure. As before, from the volume of nitrogen consumed per unit of time to keep the temperature T inside the enclosure constant, the enthalpy due to tunnel losses is determined per unit of time.
  • the enthalpy losses of the tunnel are proportional over time, the proportionality coefficient can be approximated based on the average temperature in the tunnel by a polynomial of degree 2.
  • the installation described here allows accurately determine the actual temperature of exit of articles and not just a temperature estimated of these. Indeed, the temperature calculated in this installation takes into account the number of articles actually introduced into the freezing tunnel and the amount of cryogenic fluid actually introduced.
  • the detection means used in the present installation are insensitive to temperature prevailing in the immediate vicinity of the entrance to the tunnel freezing. Indeed, no moving mechanical part is implementation and the optical detection means used are little influenced by low temperatures.
  • the camera 22 is arranged above of the conveyor so that it has little exposure to cold, highest temperatures found in the area installation.
  • the electrical elements of the optical barrier namely the transmitter and the receiver are separated from the conveyor by the use of fibers optics.
  • the camera and the optical barrier are arranged on the output section 16 of the conveyor.
  • the installation includes means for selection of the nature of the articles treated in the tunnel freezing so the central processing unit 24 uses the corresponding enthalpy variation curve items being processed for the purpose of calculating their outlet temperature.
  • the flow meter 40 can be replaced by a level gauge installed in the tank storage of cryogenic liquid, this gauge being adapted to indicate to unit 24 the evolution of the level in the tank.
  • the detection means described here can be implemented in a treatment facility articles for billing for the use of the processing device depending on the quantity items actually processed by the device, for example per operating hour of the installation, or per kilogram of product treated in the installation.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Theoretical Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • General Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Conveyors (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
  • General Preparation And Processing Of Foods (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Image Processing (AREA)

Description

La présente invention concerne une installation de traitement d'articles alimentaires telle que définie dans le préambule de la revendication 1. Une telle installation est, par exemple, connue du document EP-A-0 167 405.The present invention relates to an installation of article processing as defined in the preamble to the claim 1. Such an installation is, for example, known from document EP-A-0 167 405.

L'invention concerne les installations de traitement d'articles alimentaires, par exemple des installations surgélation d'articles alimentaires, tels que des portions de viande hachée ou encore des filets de poisson, des plats préparés, des produits laitiers, ou bien des produits de viennoiserie. On comprendra que la liste donnée précédemment ne peut être considérée comme limitative mais est en fait purement illustrative des nombreuses possibilités de l'industrie alimentaire.The invention relates to food processing facilities, for example example of installations freezing of food items, such as portions minced meat or fish fillets, dishes prepared, dairy products, or pastries. It will be understood that the list given previously cannot be considered as limiting but is in fact purely illustrative of the many possibilities of the food industry.

Les installations connues de surgélation comportent par exemple un tunnel de surgélation traversé de part en part par un convoyeur à bande sur lequel sont déposés les articles à congeler. Le convoyeur à bande circule en continu au travers du tunnel de surgélation.Known deep freezing systems include for example a deep freezing tunnel leaves by a belt conveyor on which the items to be frozen. The belt conveyor runs in continuous through the freezing tunnel.

Le tunnel de surgélation est alimenté par un fluide cryogénique, tel que de l'azote liquide ou du dioxyde de carbone liquide. Ce fluide cryogénique est mis en contact avec les articles à traiter. Au contact des articles, le fluide cryogénique se vaporise, transférant ainsi des frigories aux articles.The freezing tunnel is supplied with a fluid cryogenic, such as liquid nitrogen or dioxide liquid carbon. This cryogenic fluid is brought into contact with the articles to be treated. In contact with the articles, the cryogenic fluid vaporizes, thereby transferring frigories to articles.

Il est connu de disposer en amont des tunnels de surgélation des moyens de détection des articles introduits dans le tunnel. Ces moyens assurent par exemple la détermination du nombre d'articles ou de la masse d'articles traités par le tunnel. Ils comportent de manière classique des balances permettant de déterminer en continu le poids des articles introduits dans le tunnel de surgélation.It is known to have upstream tunnels of freezing of the means of detection of the articles introduced in the tunnel. These means ensure, for example, determination of the number of articles or the mass of articles processed through the tunnel. They behave so classic scales for continuous determination the weight of the articles introduced into the tunnel freezing.

Ces balances comportent généralement un convoyeur à bande disposé en amont du convoyeur à bande du tunnel de surgélation. Des organes de pesée sont disposés au-dessous du convoyeur afin de déterminer en continu le poids des articles circulant sur celui-ci. Dans le cas où plusieurs articles, par exemple des portions de viande hachée, sont disposés côte à côte dans la largeur du convoyeur, plusieurs organes de pesée sont disposés côte à côte suivant les trajets de déplacement des articles.These scales generally include a conveyor belt placed upstream of the belt conveyor of the tunnel freezing. Weighing devices are arranged below of the conveyor in order to continuously determine the weight of articles circulating on this one. In the event that several items, for example portions of minced meat, are arranged side by side across the width of the conveyor, several weighing devices are arranged side by side following the movement paths of the articles.

Les organes de pesée utilisés dans les moyens de détection connus actuellement comportent des pièces mobiles et mettent en oeuvre un mécanisme de pesage sophistiqué. Ce mécanisme est sensible à l'influence de la température. En particulier, les organes de pesée sont sujets à des blocages dus au gel lorsque ceux-ci sont mis en oeuvre à une très basse température.The weighing devices used in the means of detection currently known include moving parts and implement a weighing mechanism sophisticated. This mechanism is sensitive to the influence of temperature. In particular, the weighing devices are prone to freezing blockages when put on used at a very low temperature.

Dans ces conditions, les balances connues doivent être disposées à l'écart du tunnel de surgélation afin d'éviter les dysfonctionnements résultant des basses températures.In these conditions, the known scales must be placed away from the freezing tunnel so avoid malfunctions resulting from bass temperatures.

Aussi, les organes de pesée ne peuvent être associés directement au convoyeur du tunnel de surgélation.Also, the weighing devices cannot be directly associated with the conveyor of the freezing tunnel.

En conséquence, il est nécessaire de prévoir des moyens de transfert des articles depuis le convoyeur propre aux balances vers le convoyeur propre au tunnel de surgélation. L'utilisation de tels moyens de transfert occasionne des dégradations sur les articles lors de leur transfert.Consequently, it is necessary to provide means of transferring the articles from the clean conveyor scales to the conveyor of the tunnel freezing. The use of such means of transfer causes damage to the articles when they are transfer.

On pourra également se reporter au document EP-167405 qui décrit une installation de congélation d'articles utilisant une détermination du taux de charge du convoyeur à l'aide d'une caméra vidéo.Reference may also be made to document EP-167405 which describes an article freezing installation using a charge rate determination of the conveyor using a video camera.

Toujours à titre illustratif des exemples d'applications où il est avantageux de pouvoir déterminer la masse, taille, ou surface des articles entrant dans de tels tunnels ou appareils de traitement de produits alimentaires, on peut citer le cas des machines de conditionnement de produits alimentaires sous emballage, emprisonnant une atmosphère comportant de l'ozone.Still by way of illustration of the examples applications where it is advantageous to be able to determine the mass, size, or area of items falling within such tunnels or product processing devices food, we can cite the case of packaging of food products in packaging, trapping an atmosphere containing ozone.

On utilise ainsi par exemple :

  • des atmosphères N2/CO2/O2/O3, par exemple pour des viandes ou encore des poissons. A titre illustratif, on utilisera ici typiquement, selon le produit visé, des atmosphères à 1000 à 15000 ppm/poids d'ozone, comportant de quelques % à quelques dizaines de % d'oxygène, et quelques dizaines de % de CO2;
  • des atmosphères N2/O2/O3, par exemple pour des végétaux (même si dans certains cas il peut se produire que pour des végétaux l'atmosphère comporte un peu de CO2), de telles atmosphères comportant typiquement, selon le produit visé, jusqu'à 1500 ppm/poids d'ozone.
We use for example:
  • N 2 / CO 2 / O 2 / O 3 atmospheres, for example for meat or fish. By way of illustration, we will typically use here, depending on the product concerned, atmospheres at 1000 to 15000 ppm / weight of ozone, comprising from a few% to a few tens of% oxygen, and a few tens of% CO 2 ;
  • N 2 / O 2 / O 3 atmospheres, for example for plants (although in some cases it may happen that for plants the atmosphere contains a little CO 2 ), such atmospheres typically comprising, depending on the product target, up to 1500 ppm / weight of ozone.

Or, on a par ailleurs clairement démontré que l'ozone réagit davantage en fonction de la surface du produit en présence, qu'en fonction par exemple de sa masse ou son volume. On comprend alors tout l'intérêt qu'il y a à déterminer correctement la surface des produits entrant, de façon par exemple à rétroagir sur la quantité d'ozone produite par l'ozoneur afin de s'adapter efficacement à cette surface, par exemple en fonction d'une courbe d'étalonnage préétablie.However, it has also been clearly demonstrated that ozone reacts more depending on the surface of the product in presence, that depending for example on its mass or its volume. We then understand all the interest there is in correctly determine the area of incoming products, way for example to feed back on the amount of ozone produced by the ozonator in order to adapt effectively to this surface, for example as a function of a curve preset calibration.

L'invention a pour but d'apporter une solution aux inconvénients mentionnés précédemment et en particulier de fournir une installation de traitement d'articles assurant une détection des articles traités par l'appareil directement sur le convoyeur associé à l'appareil et qui soit insensible à l'influence de la température, mais permettant également la détermination de la température réelle des articles en sortie d'installation.The invention aims to provide a solution to disadvantages mentioned above and in particular of provide an item processing facility ensuring detection of articles processed by the device directly on the conveyor associated with the device and which either insensitive to the influence of temperature, but also allowing the determination of the actual temperature of outgoing items installation.

A cet effet, l'invention a pour objet une installation telle que définie en revendication 1. To this end, the subject of the invention is a installation as defined in claim 1.

On comprend que la caméra associée aux moyens de traitement d'image permet de déterminer une valeur représentative de la quantité et, le cas échéant, de la qualité des articles introduits dans l'appareil, par exemple le nombre des articles ou le volume de ceux-ci, ou encore le taux d'occupation du convoyeur, sans mettre en oeuvre de moyen mécanique sensible aux effets de la température. De plus, l'image étant prise directement sur le convoyeur de transfert de l'appareil de traitement, l'installation est d'un encombrement réduit et ne nécessite aucun transfert entre des moyens de caractérisation et l'appareil de traitement proprement dit.We understand that the camera associated with the means of image processing determines a value representative of the quantity and, where appropriate, the quality of the articles introduced into the device, for example the number of items or their volume, or the rate occupancy of the conveyor, without using any means mechanical sensitive to the effects of temperature. Moreover, the image being taken directly on the conveyor transfer of the treatment device, the installation is small footprint and requires no transfer between characterization means and the apparatus of actual treatment.

Suivant des modes particuliers de réalisation, l'invention peut comporter l'une ou plusieurs des caractéristiques suivantes :

  • la direction de prise de vue de ladite caméra s'étend sensiblement perpendiculairement au plan de déplacement dudit convoyeur ;
  • ladite unité de traitement d'informations comporte des moyens de déclenchement de la prise d'une image à des instants de déclenchement prédéfinis et lesdits moyens de traitement d'image comportent des moyens de calcul d'une valeur représentative de la densité d'articles sur le convoyeur à chaque instant de déclenchement à partir de ladite image numérique dudit tronçon du convoyeur à cet instant ;
  • ladite caméra est une caméra du type monochrome ou couleur ;
  • ladite caméra est une caméra du type couleur et ledit traitement d'image comprend une analyse des teintes présentes sur l'image, permettant, par une comparaison avec une teinte de référence, de déterminer ladite valeur représentative de la densité d'articles sur le convoyeur;
According to particular embodiments, the invention may include one or more of the following characteristics:
  • the direction of view of said camera extends substantially perpendicular to the plane of movement of said conveyor;
  • said information processing unit comprises means for triggering the taking of an image at predefined trigger times and said image processing means include means for calculating a value representative of the density of articles on the conveyor at each triggering instant from said digital image of said section of the conveyor at this instant;
  • said camera is a monochrome or color type camera;
  • said camera is a color type camera and said image processing comprises an analysis of the hues present on the image, making it possible, by comparison with a reference hue, to determine said value representative of the density of articles on the conveyor ;

On comprend alors que selon un tel mode de réalisation, il est possible de se « contenter » de l'information « densité d'articles sur le convoyeur », ou encore d'utiliser cette information en combinaison avec la vitesse de défilement du convoyeur, pour avoir accès à la quantité moyenne de produits traités dans l'enceinte par unité de temps;

  • l'installation comporte des moyens de mise en place des articles sur ledit convoyeur suivant un motif prédéterminé, reproduit séquentiellement sur ledit convoyeur avec une quantité variable d'articles pour chaque motif, et elle comporte, reliés à ladite unité de traitement d'informations, des moyens de comptage du nombre de motifs circulant en regard de la caméra, et ladite unité de traitement d'informations comporte des moyens d'évaluation de la valeur représentative de la quantité d'articles traités à partir de ladite valeur représentative de la densité d'articles sur le convoyeur calculé à chaque instant de déclenchement et du nombre de motifs comptés ;
  • lesdits moyens de comptage comportent une barrière optique reliée à ladite unité de traitement d'informations et disposée transversalement au convoyeur, le faisceau de ladite barrière étant disposé dans le plan de déplacement des articles de manière à être interrompu par les articles circulant sur le convoyeur ;
  • la barrière optique comporte, au voisinage du convoyeur, une extrémité d'émission du faisceau et une extrémité de réception du faisceau et ces deux extrémités sont associées à des buses d'éjection d'un gaz de protection desdites extrémités, notamment d'un gaz chaud;
  • selon un autre mode de réalisation des moyens de comptage, ceux-ci comportent, au voisinage du convoyeur, une barrière d'ultrasons ou de micro-ondes, reliée à ladite unité de traitement d'informations et disposée transversalement au convoyeur, le faisceau de ladite barrière étant disposé dans le plan de déplacement des articles (P) de manière à être interrompu par les articles (P) circulant sur le convoyeur ;
  • ladite caméra est une caméra du type Infra-Rouge et ledit traitement d'image permet d'obtenir outre une valeur représentative de la densité d'articles sur le convoyeur (comme dans le cas des autres types de caméra évoqués) une valeur représentative de la température des articles sur le convoyeur ;
  • lesdits moyens de traitement d'image comportent des moyens de différenciation sur ladite image des zones du convoyeur recouvertes par un article et des zones du convoyeur laissées libres, ainsi que des moyens d'analyse desdites zones différenciées sur ladite image pour la détermination d'une valeur représentative de la quantité d'articles traités ;
  • lesdits moyens d'analyse desdites zones différenciées comportent des moyens d'établissement, sur toute l'étendue de l'image, d'un premier histogramme représentatif du nombre de pixels correspondant aux zones du convoyeur recouvertes par un article pour chaque ligne de l'image suivant la direction de déplacement du convoyeur, des moyens d'établissement, sur toute l'étendue de l'image, d'un second histogramme représentatif du nombre de pixels correspondant aux zones du convoyeur recouvertes par un article pour chaque ligne de l'image suivant la direction perpendiculaire à la direction de déplacement du convoyeur et des moyens de comparaison des valeurs des pics des premier et second histogrammes ainsi établis avec des premières et secondes valeurs de seuil pour la détermination de la densité d'articles traités ;
  • ladite unité de traitement d'informations comporte des moyens de mémorisation de la courbe de variation d'enthalpie d'un article en fonction de sa température, et des moyens de détermination de la température de sortie d'un article à partir de ladite courbe d'enthalpie, de la quantité de fluide cryogénique mesurée, de la valeur représentative de la quantité d'articles traites et de la température initiale des articles.
It will then be understood that, according to such an embodiment, it is possible to “be satisfied” with the information “density of articles on the conveyor”, or even to use this information in combination with the speed of travel of the conveyor, to have access to the average quantity of products treated in the enclosure per unit of time;
  • the installation includes means for placing articles on said conveyor in a predetermined pattern, reproduced sequentially on said conveyor with a variable quantity of articles for each pattern, and it comprises, connected to said information processing unit, means for counting the number of patterns flowing opposite the camera, and said information processing unit comprises means for evaluating the value representative of the quantity of articles treated from said value representative of the density d 'articles on the conveyor calculated at each triggering instant and the number of patterns counted;
  • said counting means comprise an optical barrier connected to said information processing unit and arranged transversely to the conveyor, the beam of said barrier being arranged in the plane of movement of the articles so as to be interrupted by the articles circulating on the conveyor;
  • the optical barrier comprises, in the vicinity of the conveyor, a beam emission end and a beam reception end and these two ends are associated with nozzles for ejecting a gas for protecting said ends, in particular a gas hot;
  • according to another embodiment of the counting means, these comprise, in the vicinity of the conveyor, an ultrasound or microwave barrier, connected to said information processing unit and arranged transversely to the conveyor, the beam of said barrier being arranged in the plane of movement of the articles (P) so as to be interrupted by the articles (P) circulating on the conveyor;
  • said camera is an infrared type camera and said image processing makes it possible to obtain, in addition to a value representative of the density of articles on the conveyor (as in the case of the other types of camera mentioned), a value representative of the temperature of items on the conveyor;
  • said image processing means comprise means for differentiating on said image the areas of the conveyor covered by an article and the areas of the conveyor left free, as well as means for analyzing said differentiated areas on said image for determining a value representative of the quantity of articles treated;
  • said means for analyzing said differentiated zones comprise means for establishing, over the entire extent of the image, a first histogram representative of the number of pixels corresponding to the zones of the conveyor covered by an article for each line of the image following the direction of movement of the conveyor, means for establishing, over the entire extent of the image, a second histogram representative of the number of pixels corresponding to the zones of the conveyor covered by an article for each line of the image in the direction perpendicular to the direction of movement of the conveyor and of means for comparing the peak values of the first and second histograms thus established with first and second threshold values for determining the density of articles treated;
  • said information processing unit comprises means for memorizing the enthalpy variation curve of an article as a function of its temperature, and means for determining the outlet temperature of an article from said curve enthalpy, of the quantity of cryogenic fluid measured, of the value representative of the quantity of articles treated and of the initial temperature of the articles.

L'invention sera mieux comprise à la lecture de la description qui va suivre, donnée uniquement à titre d'exemple et faite en se référant aux dessins sur lesquels :

  • la figure 1 est une vue schématique d'une installation de surgélation de produits alimentaires, par exemple de portions de viande hachée selon l'invention, le tunnel de surgélation étant vu de dessus ;
  • la figure 2 est une vue schématique de côté du tunnel de surgélation de la figure 1 ;
  • la figure 3 est une vue schématique explicitant le fonctionnement des moyens de traitement d'images ;
  • la figure 4 est un organigramme explicitant les étapes mises en oeuvre par les moyens de traitement d'images ;
  • la figure 5 est une courbe représentant l'enthalpie transférée à un kilogramme d'articles introduits dans le tunnel en fonction de la température ; et
  • la figure 6 est une courbe représentant l'évolution de l'enthalpie d'un litre d'azote initialement liquide en fonction de la température finale, pour différentes pressions.
The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings in which:
  • Figure 1 is a schematic view of an installation for freezing food products, for example portions of minced meat according to the invention, the freezing tunnel being seen from above;
  • Figure 2 is a schematic side view of the freezing tunnel of Figure 1;
  • Figure 3 is a schematic view explaining the operation of the image processing means;
  • FIG. 4 is a flowchart explaining the steps implemented by the image processing means;
  • FIG. 5 is a curve representing the enthalpy transferred to a kilogram of articles introduced into the tunnel as a function of the temperature; and
  • Figure 6 is a curve showing the evolution of the enthalpy of a liter of initially liquid nitrogen as a function of the final temperature, for different pressures.

L'installation représentée sur les figures 1 et 2 comporte un tunnel de surgélation 10 ouvert à ses deux extrémités. Il comporte une ligne d'alimentation 11 en fluide cryogénique, de l'azote liquide par exemple. Le tunnel est traversé par un convoyeur à bande 12 circulant suivant la direction X-X dans le sens de la flèche F1. Le convoyeur fait saillie de chaque côté du tunnel de surgélation 10. En particulier, il comporte un tronçon d'entrée 14 pour l'introduction dans le tunnel des articles à congeler et un tronçon de sortie 16 pour l'évacuation des articles congelés.The installation shown in Figures 1 and 2 has a freezing tunnel 10 open to both ends. It includes a supply line 11 in cryogenic fluid, for example liquid nitrogen. The tunnel is traversed by a conveyor belt 12 circulating in the direction X-X in the direction of the arrow F1. The conveyor protrudes from each side of the tunnel freezing 10. In particular, it includes a section input 14 for the entry into the tunnel of articles to be frozen and an outlet section 16 for the evacuation of frozen items.

Le tunnel représenté est supposé adapté pour la congélation de portions de viande hachée de forme sensiblement ovale. Ces portions sont désignées par la lettre P sur les figures.The tunnel shown is assumed to be suitable for freezing portions of roughly shaped meat oval. These portions are designated by the letter P in the figures.

Le tronçon d'entrée 14 du convoyeur est disposé en sortie d'une machine M de mise en forme des portions. Cette machine est adaptée pour produire simultanément de une à six portions de viande hachée.The inlet section 14 of the conveyor is arranged in output of a machine M for shaping the portions. This machine is suitable for producing simultaneously from one to six servings of minced meat.

Des moyens de transfert non représentés sont prévus afin de prélever les portions en sortie de la machine de mise en forme M et de déposer celles-ci sur le tronçon d'entrée 14. En particulier, les moyens de transfert sont adaptés pour déposer les portions P séquentiellement sur le convoyeur circulant en continu suivant un motif prédéfini.Transfer means not shown are provided to take the portions out of the machine formatting M and depositing these on the section input 14. In particular, the means of transfer are adapted to deposit the portions P sequentially on the conveyor circulating continuously according to a predefined pattern.

Dans l'exemple décrit, les portions P sont disposées en lignes suivant la largeur Y-Y du convoyeur 12, comme représenté sur la figure 1. Ainsi, les portions P sont alignées suivant des rangées pouvant comporter de une à six portions, en fonction du nombre de portions simultanément produites par le dispositif de mise en forme M.In the example described, the portions P are arranged in lines along the width Y-Y of the conveyor 12, as shown in Figure 1. Thus, the portions P are aligned in rows which may include a to six servings, depending on the number of servings simultaneously produced by the shaping device Mr.

Selon l'invention, l'installation comporte des moyens 20 de détection des articles traités dans le tunnel. Ces moyens 20 comportent ici une caméra 22 reliée à une unité de traitement d'informations 23. Cette dernière comporte une unité centrale de calcul 24 comportant notamment des moyens de traitement d'une image numérique recueillie par ladite caméra.According to the invention, the installation comprises means 20 for detecting the articles treated in the tunnel. These means 20 here comprise a camera 22 connected to a information processing unit 23. The latter comprises a central computing unit 24 comprising in particular means for processing a digital image collected by said camera.

Comme représenté sur les figures 1 et 2, la caméra 22 est disposée au-dessus du tronçon d'entrée 14 du convoyeur avec sa direction de prise de vue s'étendant sensiblement perpendiculairement au plan de déplacement du convoyeur 12.As shown in Figures 1 and 2, the camera 22 is arranged above the inlet section 14 of the conveyor with its shooting direction extending substantially perpendicular to the plane of movement of the conveyor 12.

La caméra est pour le mode de réalisation représenté adaptée pour la prise d'une image numérique monochrome couvrant l'essentiel de la surface du tronçon 14.The camera is for the embodiment shown suitable for taking a digital image monochrome covering most of the section surface 14.

Un exemple d'image recueillie par la caméra 22 est représenté sur la figure 3. Cette image, désignée par la référence 25, fait apparaítre deux rangées, notées R1, R2, comportant chacune cinq taches noires correspondant aux zones du convoyeur recouvertes par un article La surface du convoyeur laissée libre apparaít en blanc sur l'image 25.An example of image collected by the camera 22 is shown in Figure 3. This image, designated by the reference 25, shows two rows, noted R1, R2, each with five black spots corresponding to conveyor areas covered by an article Surface of the conveyor left free appears in white on the image 25.

Les moyens 24 de traitement de l'image numérique sont adaptés pour déterminer une valeur représentative de la quantité d'articles traités par le tunnel. Cette quantité est par exemple le nombre n d'articles introduits, le volume d'articles introduits, ou encore le taux d'occupation du convoyeur.The means 24 for processing the digital image are suitable for determining a representative value of the quantity of articles treated by the tunnel. This quantity is for example the number n of articles introduced, the volume of articles introduced, or the rate occupancy of the conveyor.

L'unité centrale de calcul 24 est par exemple formée par un micro-ordinateur comportant une interface de liaison à la caméra 22 adaptée pour le recueil d'une image numérisée. Un programme de traitement d'images est chargé dans le micro-ordinateur afin d'analyser l'image produite par ladite caméra. Celui-ci sera décrit ultérieurement en référence à la figure 4.The central computing unit 24 is for example formed by a microcomputer comprising an interface connection to camera 22 suitable for collecting an image digitized. An image processing program is loaded in the microcomputer in order to analyze the image produced by said camera. This will be described later in reference to figure 4.

L'unité de traitement d'informations 23 comporte des moyens de déclenchement de la prise d'une image à une fréquence prédéterminée (c'est à dire de transfert d'une image de la caméra vers l'unité), fréquence qui on le comprend dépendra du type de traitement réalisé ensuite par l'unité, fréquence donc suffisamment faible pour permettre un traitement informatique de l'image. Cette fréquence est par exemple de l'ordre de 0,3 Hertz mais pourra couramment varier entre quelques dixièmes d'Hertz et quelques dizaines d'Hertz.The information processing unit 23 comprises means for triggering the taking of an image at a predetermined frequency (i.e. transfer of a image from camera to unit), frequency which is includes will depend on the type of treatment then performed by the unit, frequency therefore sufficiently low to allow computer image processing. This frequency is for example of the order of 0.3 Hertz but may commonly vary between a few tenths of Hertz and a few tens Hertz.

Par ailleurs, l'installation représentée sur la figure 1 comporte une barrière optique 26 comportant deux tronçons de fibre optique 28, 30 alignés, dont les extrémités en regard 28A, 30A sont disposées face à face de part et d'autre du convoyeur 12.Furthermore, the installation shown on the Figure 1 includes an optical barrier 26 comprising two sections of optical fiber 28, 30 aligned, the opposite ends 28A, 30A are arranged face to face with on either side of the conveyor 12.

Le mode de réalisation illustré ici repose donc sur l'utilisation combinée d'une caméra monochrome et d'une barrière optique.The embodiment illustrated here is therefore based on the combined use of a monochrome camera and a optical barrier.

Le tronçon 28 de fibre optique comporte à son autre extrémité une diode électroluminescente 32 alimentée par une source d'alimentation électrique en vue de l'établissement d'un faisceau lumineux permanent au travers de la fibre 28. L'autre extrémité de la fibre 30 est associée à un photodétecteur 34 relié à l'unité centrale de calcul 24. Les fibres 28 et 30 sont disposées à un niveau tel que le faisceau lumineux traversant le convoyeur suivant la direction Y-Y et s'étendant depuis la fibre 28 vers la fibre 30 est interrompu par les rangées d'articles circulant sur le convoyeur.The section 28 of optical fiber has at its other end a light emitting diode 32 powered by a source of electrical power for the establishment of a permanent light beam through of fiber 28. The other end of fiber 30 is associated with a photodetector 34 connected to the central processing unit calculus 24. Fibers 28 and 30 are arranged at a level such as the light beam passing through the conveyor in the direction Y-Y and extending from the fiber 28 to fiber 30 is interrupted by rows of items traveling on the conveyor.

Le photodétecteur 34, relié à l'unité 23, permet ainsi de déterminer le nombre d'interruptions du faisceau, lequel correspond au nombre de rangées d'articles pénétrant dans le tunnel de surgélation 10. Si les articles sont disposés suivant un motif différent d'une rangée, par exemple un arc de cercle, la barrière optique 26 exerce de manière identique une fonction de comptage du nombre de motifs entrant dans le tunnel, et ce indépendamment du nombre d'articles contenus dans chaque motif.The photodetector 34, connected to the unit 23, allows thus to determine the number of beam interruptions, which corresponds to the number of rows of penetrating items in the freezing tunnel 10. If the items are arranged in a different pattern in a row, by example an arc of a circle, the optical barrier 26 exerts identical function of counting the number of patterns entering the tunnel, regardless of number of items in each pattern.

A chacune des extrémités libres 28A, 30A des fibres optiques, sont prévues des buses 36, 38 d'éjection d'un gaz sec, notamment de l'azote, sur les extrémités des fibres optiques afin d'assurer leur protection contre les effets du froid.At each of the free ends 28A, 30A of the fibers optics, nozzles 36, 38 are provided for ejecting a gas dry, especially nitrogen, on the ends of the fibers optics to protect them from the effects cold.

Ces buses sont reliées à des moyens d'alimentation en gaz sec, ce gaz étant à une température supérieure à la température régnant dans l'enceinte du tunnel. La température du gaz sec éjecté est par exemple égale à la température ambiante (20°C).These nozzles are connected to supply means as dry gas, this gas being at a temperature higher than the temperature prevailing in the tunnel enclosure. The temperature of the dry gas ejected is for example equal to the room temperature (20 ° C).

L'unité centrale de calcul 24 est reliée à un débitmètre 40 adapté pour déterminer le débit de fluide cryogénique introduit dans le tunnel 10.The central computing unit 24 is connected to a flow meter 40 suitable for determining the fluid flow cryogenic introduced into tunnel 10.

En outre, l'unité 24 est reliée à des moyens de mémorisation 42 comportant, pour chaque type d'article pouvant être traité dans le tunnel, une courbe G5, propre à l'article, de variation de son enthalpie en fonction de sa température.In addition, the unit 24 is connected to storage means 42 comprising, for each type of article which can be treated in the tunnel, a curve G 5 , specific to the article, of variation of its enthalpy as a function of its temperature.

Un écran d'affichage 44 est relié à l'unité centrale de calcul 24 afin d'afficher la température des articles en sortie du tunnel.A display screen 44 is connected to the unit data center 24 in order to display the temperature of the items leaving the tunnel.

L'installation selon l'invention fonctionne de la manière suivante.The installation according to the invention operates from the next way.

Alors que les articles circulent en continu sur le convoyeur, la caméra 22 relève à une fréquence donnée une image du tronçon 14 et transmet celle-ci à l'unité de traitement d'informations 23. Elle est alors analysée par le programme de traitement d'image.While the articles circulate continuously on the conveyor, the camera 22 detects at a given frequency a image of section 14 and transmits it to the information processing 23. It is then analyzed by the image processing program.

Le programme de traitement d'images mis en oeuvre comporte une première étape de filtrage de l'image issue de la caméra. Cette première étape, désignée par La référence 50 sur l'organigramme de la figure 4, consiste à comparer le niveau de gris de chaque pixel de l'image à une valeur de référence et à remplacer le pixel considéré par un pixel blanc si le niveau de gris est inférieur à la valeur de référence et par un pixel noir si le niveau de gris est supérieur à la valeur de référence. Ainsi, il en résulte une image telle que celle représentée sur la figure 3 dans laquelle les zones du convoyeur recouvertes par un article forment des taches noires sur un fond blanc.The image processing program implemented includes a first step of filtering the image from the camera. This first step, designated by The reference 50 on the flow diagram of FIG. 4, consists in comparing the gray level of each pixel of the image to a value of reference and to replace the pixel considered by a pixel white if the gray level is less than the value of reference and with a black pixel if the gray level is greater than the reference value. So it results an image like the one shown in Figure 3 in which areas of the conveyor covered by an article form black spots on a white background.

L'image est positionnée de sorte que la direction X-X d'avancement du convoyeur s'étende suivant la hauteur de l'image et que la largeur Y-Y du convoyeur, direction perpendiculaire à la direction d'avancement du convoyeur s'étende suivant la largeur de l'image.The image is positioned so that the direction X-X of advancement of the conveyor extends according to the height of the image and that the width Y-Y of the conveyor, direction perpendicular to the direction of travel of the conveyor expands along the width of the image.

A l'étape 52, le programme établit un histogramme 52A du nombre de pixels noirs suivant la direction X-X. Cet histogramme représente, pour chaque ligne parallèle à l'axe Y-Y de l'image numérisée, le nombre total de pixels noirs contenus dans cette ligne. Le calcul est effectué pour toutes les lignes de l'image.In step 52, the program establishes a histogram 52A of the number of black pixels in the X-X direction. This histogram represents, for each line parallel to the axis Y-Y of the scanned image, the total number of black pixels contained in this line. The calculation is made for all the lines of the image.

Comme représenté sur la figure 3, l'histogramme 52A comporte deux pics successifs correspondant aux deux rangées R1 et R2.As shown in Figure 3, the histogram 52A has two successive peaks corresponding to the two rows R1 and R2.

De manière analogue, un histogramme 54A est établi à l'étape 54 en effectuant la somme des pixels noirs pour chaque ligne de l'image numérisée parallèle à l'axe X-X. Comme représenté sur la figure 3, l'histogramme 54A comporte cinq pics correspondant aux cinq articles contenus dans les deux rangées R1 et R2.Similarly, a histogram 54A is established in step 54 by summing the black pixels for each line of the scanned image parallel to the X-X axis. As shown in Figure 3, the histogram 54A has five peaks corresponding to the five articles contained in the two rows R1 and R2.

Aux étapes 56 et 58, le programme détermine le nombre de pics contenus dans les histogrammes 52A et 54A.In steps 56 and 58, the program determines the number of peaks contained in histograms 52A and 54A.

A cet effet, le programme compte par exemple, pour chaque histogramme, le nombre de pics dont la hauteur excède une valeur de référence prédéterminée S1, S2 représentée par une ligne pointillée sur la figure 3.For this purpose, the program counts for example, for each histogram, the number of peaks including the height exceeds a predetermined reference value S1, S2 represented by a dotted line in Figure 3.

A partir du nombre de pics identifiés sur les histogrammes 52A et 54A, le programme calcule, à l'étape 60, le nombre d'articles figurant sur l'image et en particulier le nombre d'articles par rangée. Cette dernière valeur est indicative de la densité d'articles sur le convoyeur à l'instant considéré.From the number of peaks identified on the histograms 52A and 54A, the program calculates, in step 60, the number of items shown in the image and in especially the number of items per row. This last value is indicative of the density of items on the conveyor at the instant considered.

Comme il apparaítra clairement à l'homme du métier, l'exemple ci-dessus développé illustre le cas de produits déposés en ligne selon une forme régulière, on comprendra qu'alors si la mise en place des produits sur le convoyeur ne suit pas une telle régularité, l'algorithme utilisé sera différent.As will be clear to those skilled in the art, the example above developed illustrates the case of products filed online in a regular form, we will understand only then if the placement of the products on the conveyor does not follow such a pattern, the algorithm used will be different.

L'unité centrale de calcul 24 reliée à la barrière optique 26 permet de déterminer en continu avec précision le nombre de rangées d'articles traitées par le tunnel.The central computing unit 24 connected to the barrier optics 26 allows continuous determination with precision the number of rows of items processed through the tunnel.

A partir du nombre d'articles par rangée et du nombre réel de rangées pénétrant dans le tunnel, l'unité centrale de calcul 24 détermine en continu le nombre d'articles introduits à l'intérieur du tunnel.From the number of items per row and the actual number of rows entering the tunnel, unit data center 24 continuously determines the number of articles brought inside the tunnel.

En variante, à partir de la hauteur des pics de chaque histogramme, le programme détermine, à l'étape 60, les dimensions des articles suivant les deux directions s'étendant perpendiculairement à la direction de prise de vue de la caméra.Alternatively, from the height of the peaks of each histogram, the program determines, in step 60, the dimensions of the articles in both directions extending perpendicular to the grip direction camera view.

A partir de celles-ci, le programme détermine le taux d'occupation du convoyeur, c'est-à-dire le rapport de la surface occupée par les articles à traiter à la surface libre du convoyeur contenue dans l'image analysée.From these, the program determines the occupancy rate of the conveyor, i.e. the the surface occupied by the articles to be treated on the surface free of the conveyor contained in the analyzed image.

Le taux d'occupation du convoyeur constitue une autre valeur représentative de la densité d'articles sur le convoyeur.The occupancy rate of the conveyor constitutes a other value representative of the density of articles on the conveyor.

Comme précédemment, l'unité centrale de calcul 24 détermine en continu à partir du taux d'oc:cupation du convoyeur et du nombre réel de rangées d'articles pénétrant dans le tunnel, une valeur représentative de la quantité d'articles pénétrant à l'instant donné dans le tunnel. Cette valeur est par exemple le produit du taux d'occupation par le nombre de rangées entrant dans le tunnel par unité de temps.As before, the central computing unit 24 continuously determines from the oc rate: collection of conveyor and the actual number of rows of items penetrating in the tunnel, a value representative of the quantity items entering the tunnel at any given time. This value is for example the product of the rate occupancy by the number of rows entering the tunnel per unit of time.

On comprend que dans les deux variantes, bien que la caméra 22 ne fournisse pas une image de tous les articles entrant dans le tunnel, du fait de la vitesse élevée de circulation du convoyeur et de la lenteur relative de l'unité de calcul, il est possible par l'utilisation combinée de la caméra et de la barrière optique de déterminer avec précision une valeur représentative de la quantité d'articles traités dans l'installation.We understand that in both variants, although camera 22 does not provide an image of all items entering the tunnel, due to speed high conveyor circulation and slowness relative to the calculation unit, it is possible by the combined use of the camera and the barrier optics to accurately determine a representative value the quantity of articles treated in the installation.

En vue du calcul de la température Ts des articles en sortie du tunnel, l'unité centrale de calcul 24 comporte un programme permettant de déterminer en continu cette température à partir d'une courbe mémorisée G5 de variation d'enthalpie, du volume q de fluide cryogénique introduit dans le tunnel par unité de temps, de la pression et de la température du fluide cryogénique, ainsi que du nombre n d'articles, dont la masse est connue, introduits par unité de temps dans le tunnel et de leur température d'entrée Te. Dans l'exemple décrit, le fluide cryogénique est de l'azote liquide. Il pourrait être remplacé par du bioxyde de carbone, de l'argon ou tout autre fluide.With a view to calculating the temperature Ts of the articles leaving the tunnel, the central computing unit 24 includes a program making it possible to continuously determine this temperature from a stored curve G 5 of enthalpy variation, of the volume q of cryogenic fluid introduced into the tunnel per unit of time, the pressure and temperature of the cryogenic fluid, as well as the number n of articles, the mass of which is known, introduced per unit of time into the tunnel and their temperature input Te. In the example described, the cryogenic fluid is liquid nitrogen. It could be replaced by carbon dioxide, argon or any other fluid.

La courbe G5, représentée sur la figure 5, traduit la variation de l'enthalpie H d'un kilogramme d'articles lorsque la température de celui-ci passe de la température de -189°C (température de l'azote liquide à la pression de stockage par exemple égale à 2 bars absolus) à une température T quelconque donnée en abscisse et à la pression atmosphérique.The curve G 5 , represented in FIG. 5, translates the variation of the enthalpy H of a kilogram of articles when the temperature thereof changes from the temperature of -189 ° C (temperature of liquid nitrogen to the storage pressure for example equal to 2 bars absolute) at any temperature T given on the abscissa and at atmospheric pressure.

La courbe d'enthalpie G5, mémorisée dans les moyens de mémorisation 42, est déterminée expérimentalement.The enthalpy curve G 5 , stored in the storage means 42, is determined experimentally.

A cet effet, on immerge un kilogramme d'articles à une température initiale T connue dans un récipient de Dewar empli d'azote liquide et on mesure, par exemple à l'aide d'une balance, la quantité d'azote vaporisé pour amener les articles de la température initiale à la température de l'azote liquide (-196°C) à la pression atmosphérique.For this purpose, a kilogram of articles is immersed in a known initial temperature T in a container of Dewar filled with liquid nitrogen and we measure, for example at using a balance, the amount of nitrogen vaporized to bring items from initial temperature to liquid nitrogen temperature (-196 ° C) at pressure atmospheric.

L'enthalpie H transférée aux articles dans le récipient de Dewar correspond à l'enthalpie de vaporisation de l'azote à la pression considérée. Cette valeur est proportionnelle à la quantité mesurée d'azote vaporisé.The enthalpy H transferred to articles in the Dewar container corresponds to the enthalpy of vaporization nitrogen at the pressure considered. This value is proportional to the measured amount of vaporized nitrogen.

L'enthalpie de vaporisation à la pression considérée d'un litre d'azote liquide est donnée sur les courbes de la figure 6 représentant la variation d'enthalpie de l'azote liquide en fonction de la température pour différentes pressions de stockage à l'équilibre thermodynamique. Sur cette figure, chaque courbe correspond à une pression donnée.The enthalpy of vaporization at the pressure considered of a liter of liquid nitrogen is given on the curves of figure 6 representing the enthalpy variation of liquid nitrogen as a function of temperature for different equilibrium storage pressures thermodynamic. In this figure, each curve corresponds at a given pressure.

L'expérience est reproduite pour différentes températures initiales, un nombre de fois suffisant pour établir la courbe G5 dont l'axe des abscisses s'étend de -196°C à +50°C.The experiment is repeated for different initial temperatures, a number of times sufficient to establish the curve G 5 whose axis of the abscissae extends from -196 ° C to + 50 ° C.

Grâce à cette courbe G5, le programme chargé dans l'unité centrale de calcul 24 détermine en continu la température finale Ts d'un kilogramme d'articles en sortie de tunnel, à partir de la température d'entrée Te et de l'enthalpie DHT transférée à un kilogramme d'articles par l'azote introduit dans le tunnel.Thanks to this curve G 5 , the program loaded into the central computing unit 24 continuously determines the final temperature Ts of a kilogram of articles leaving the tunnel, from the inlet temperature Te and the enthalpy DH T transferred to a kilogram of articles by the nitrogen introduced into the tunnel.

A cet effet, le programme détermine, à partir de la courbe G5, l'enthalpie He correspondant à un kilogramme d'articles entrant dans le tunnel à la température Te. A partir de l'enthalpie DHT transférée aux articles par l'azote, il calcule l'enthalpie Hs d'un kilogramme d'articles en sortie du tunnel par la relation Hs = He - DHT.To this end, the program determines, from the curve G 5 , the enthalpy He corresponding to a kilogram of articles entering the tunnel at the temperature Te. From the enthalpy DH T transferred to the articles by nitrogen, it calculates the enthalpy Hs of a kilogram of articles leaving the tunnel by the relation Hs = He - DH T.

Grâce à la courbe G5, le programme détermine enfin la température Ts de sortie des articles, cette température correspondant à l'enthalpie Hs.Thanks to the curve G 5 , the program finally determines the temperature Ts of the articles leaving, this temperature corresponding to the enthalpy Hs.

Afin de permettre le calcul de la température Te d'entrée des articles, l'unité centrale de calcul 24 est reliée à une sonde de température mise au contact des articles immédiatement avant leur entrée dans le tunnel. Elle peut également être la température d'un bain de stabilisation dans lequel les articles ont séjourné avant leur introduction dans le tunnel.In order to allow the calculation of the temperature Te input of the articles, the central computing unit 24 is connected to a temperature probe brought into contact with items immediately before entering the tunnel. It can also be the temperature of a stabilization in which the items have stayed before their introduction into the tunnel.

L'enthalpie DHT transférée par l'azote aux articles dans le tunnel est déterminée de la manière suivante.The enthalpy DH T transferred by nitrogen to the articles in the tunnel is determined as follows.

La courbe G6 donne l'enthalpie DH libérée par un litre d'azote liquide lorsque celui-ci passe, pour une pression donnée, de sa température de liquéfaction à une température quelconque T donnée en abscisse.The curve G 6 gives the enthalpy DH released by a liter of liquid nitrogen when the latter passes, for a given pressure, from its liquefaction temperature to any temperature T given on the abscissa.

Afin de déterminer l'enthalpie libérée, le programme détermine à partir de la courbe G6 l'enthalpie DHTa libérée dans le tunnel par un litre d'azote liquide, lorsque celui-ci se vaporise et passe de sa température de stockage (-189°C) à la température Ta des gaz en sortie du tunnel.In order to determine the enthalpy released, the program determines from curve G 6 the enthalpy DH Ta released in the tunnel by a liter of liquid nitrogen, when this vaporizes and passes from its storage temperature (- 189 ° C) at the temperature Ta of the gases leaving the tunnel.

La température Ta est par exemple mesurée à l'intérieur de l'enceinte du tunnel à sa sortie (par exemple à 1 mètre avant la sortie des gaz) par une sonde de température reliée à l'unité centrale de calcul 24. Cette température Ta est généralement liée à la température de consigne du tunnel et à la température d'entrée des articles. Elle est par exemple de l'ordre de -30°C.The temperature Ta is for example measured inside from the tunnel enclosure to its exit (for example at 1 meter before the gas outlet) by a temperature probe connected to the central computing unit 24. This temperature Ta is generally related to the temperature of setpoint of the tunnel and the entry temperature of the articles. It is for example of the order of -30 ° C.

Le programme déduit ensuite l'enthalpie brute DHB transférée à un kilogramme d'articles en multipliant l'enthalpie DHTa transférée pour un litre d'azote, par le volume d'azote introduit dans le tunnel pour un kilogramme d'articles (i.e. DHB = q.DHTa/MP où MP est la masse d'articles introduits dans le tunnel par unité de temps).The program then deduces the gross enthalpy DH B transferred to one kilogram of articles by multiplying the enthalpy DH Ta transferred for one liter of nitrogen, by the volume of nitrogen introduced into the tunnel for one kilogram of articles (ie DH B = q.DH Ta / M P where M P is the mass of articles introduced into the tunnel per unit of time).

La masse MP d'articles introduits dans le tunnel par unité de temps est déterminée à partir du nombre n d'articles détectés en entrée du tunnel par unité de temps et du poids moyen des articles. The mass M P of articles introduced into the tunnel per unit of time is determined from the number n of articles detected at the entrance to the tunnel per unit of time and the average weight of the articles.

L'enthalpie DHT est ensuite calculée à partir de l'enthalpie brute DHB en tenant compte des pertes thermiques du tunnel DHP.The enthalpy DH T is then calculated from the gross enthalpy DH B taking into account the thermal losses of the tunnel DH P.

Les pertes matérielles d'enthalpie DHP du tunnel sont évaluées expérimentalement en laissant fonctionner le tunnel en l'absence d'articles pour différentes valeurs de température T régnant à l'intérieur de l'enceinte. Comme précédemment, à partir du volume d'azote consommé par unité de temps pour maintenir constante la température T à l'intérieur de l'enceinte, on détermine l'enthalpie due aux pertes du tunnel par unité de temps.The material enthalpy losses DH P of the tunnel are evaluated experimentally by leaving the tunnel to operate in the absence of articles for different temperature values T prevailing inside the enclosure. As before, from the volume of nitrogen consumed per unit of time to keep the temperature T inside the enclosure constant, the enthalpy due to tunnel losses is determined per unit of time.

Les pertes d'enthalpie du tunnel sont proportionnelles au temps, le coefficient de proportionnalité pouvant être approximé en fonction de la température moyenne dans le tunnel par un polynôme de degré 2.The enthalpy losses of the tunnel are proportional over time, the proportionality coefficient can be approximated based on the average temperature in the tunnel by a polynomial of degree 2.

L'enthalpie DHT est enfin calculée en soustrayant de l'enthalpie DHB l'enthalpie DHP des pertes matérielles du tunnel divisée par la masse d'articles introduits dans le tunnel par unité de temps (i.e. DHT = DHB - DHP/MP).The enthalpy DH T is finally calculated by subtracting the enthalpy DH B the enthalpy DH P from the material losses of the tunnel divided by the mass of articles introduced into the tunnel per unit of time (ie DH T = DH B - DH P / M P ).

On comprend que l'installation décrite ici permet de déterminer avec précision la température réelle de sortie des articles et non simplement une température estimée de ceux-ci. En effet, la température calculée dans la présente installation tient compte du nombre d'articles réellement introduits dans le tunnel de surgélation et de la quantité de fluide cryogénique réellement introduite.We understand that the installation described here allows accurately determine the actual temperature of exit of articles and not just a temperature estimated of these. Indeed, the temperature calculated in this installation takes into account the number of articles actually introduced into the freezing tunnel and the amount of cryogenic fluid actually introduced.

Les moyens de détection mis en oeuvre dans la présente installation sont insensibles à la température régnant à la proximité immédiate de l'entrée du tunnel de surgélation. En effet, aucune pièce mécanique mobile n'est mise en oeuvre et les moyens optiques de détection utilisés sont peu influencés par les basses températures.The detection means used in the present installation are insensitive to temperature prevailing in the immediate vicinity of the entrance to the tunnel freezing. Indeed, no moving mechanical part is implementation and the optical detection means used are little influenced by low temperatures.

En particulier, la caméra 22 est disposée au-dessus du convoyeur de sorte qu'elle est peu exposée au froid, les températures les plus élevées se trouvant dans la partie supérieure de l'installation.In particular, the camera 22 is arranged above of the conveyor so that it has little exposure to cold, highest temperatures found in the area installation.

Par ailleurs, les éléments électriques de la barrière optique, à savoir l'émetteur et le récepteur sont écartés du convoyeur grâce à l'utilisation des fibres optiques.In addition, the electrical elements of the optical barrier, namely the transmitter and the receiver are separated from the conveyor by the use of fibers optics.

En variante non représentée, la caméra et la barrière optique sont disposées sur le tronçon de sortie 16 du convoyeur.In a variant not shown, the camera and the optical barrier are arranged on the output section 16 of the conveyor.

Bien entendu, l'installation comporte des moyens de sélection de la nature des articles traités dans le tunnel de surgélation de sorte que l'unité centrale de calcul 24 utilise la courbe de variation d'enthalpie correspondant aux articles en cours de traitement en vue du calcul de leur température de sortie.Of course, the installation includes means for selection of the nature of the articles treated in the tunnel freezing so the central processing unit 24 uses the corresponding enthalpy variation curve items being processed for the purpose of calculating their outlet temperature.

Par ailleurs, le débitmètre 40 peut être remplacé par une jauge de niveau installée dans le réservoir de stockage de liquide cryogénique, cette jauge étant adaptée pour indiquer à l'unité 24 l'évolution du niveau dans le réservoir.Furthermore, the flow meter 40 can be replaced by a level gauge installed in the tank storage of cryogenic liquid, this gauge being adapted to indicate to unit 24 the evolution of the level in the tank.

Les moyens de détection décrits ici peuvent être mis en oeuvre dans une installation de traitement d'articles en vue de la facturation de l'utilisation de l'appareil de traitement en fonction de la quantité d'articles réellement traités par l'appareil, par exemple par heure de fonctionnement de l'installation, ou encore par kilogramme de produit traité dans l'installation. The detection means described here can be implemented in a treatment facility articles for billing for the use of the processing device depending on the quantity items actually processed by the device, for example per operating hour of the installation, or per kilogram of product treated in the installation.

Si l'invention a été tout particulièrement exemplifié dans le cas d'une détermination quantitative du nombre de produits traités dans l'enceinte, cela en utilisant la combinaison d'une caméra monochrome et d'une barrière optique, il apparaítra clairement à l'homme du métier que l'on peut, sans sortir du cadre de la présente invention, par exemple :

  • utiliser d'autres types de caméra;
  • utiliser une barrière optique faite de plusieurs faisceaux disposés l'un au dessus de l'autre dans le plan de déplacement des articles (P) de manière à être interrompus par les articles (P) circulant sur le convoyeur, et permettant d'obtenir une information de volume des articles (selon le nombre de faisceaux interrompus en hauteur lors du passage);
  • utiliser, en combinaison avec une caméra, un autre moyen de comptage qu'une barrière optique, par exemple une barrière d'ultrasons;
  • utiliser la caméra (quelque soit son type) seule, pour obtenir une information quantitative telle que le taux d'occupation du convoyeur (qui on l'a vu, en combinaison avec la vitesse de ce convoyeur permet d'avoir accès à la quantité moyenne de produits traités), et, le cas échéant, une information qualitative telle que la température des produits (que ce soit à l'entrée de l'enceinte ou à la sortie selon l'endroit où l'on positionne le système).
If the invention has been particularly exemplified in the case of a quantitative determination of the number of products treated in the enclosure, this using the combination of a monochrome camera and an optical barrier, it will appear clearly on the skilled in the art that one can, without departing from the scope of the present invention, for example:
  • use other types of cameras;
  • use an optical barrier made of several beams arranged one above the other in the plane of movement of the articles (P) so as to be interrupted by the articles (P) circulating on the conveyor, and making it possible to obtain a item volume information (depending on the number of beams interrupted in height during passage);
  • use, in combination with a camera, another counting means than an optical barrier, for example an ultrasonic barrier;
  • use the camera (whatever its type) alone, to obtain quantitative information such as the occupancy rate of the conveyor (which we have seen, in combination with the speed of this conveyor allows access to the average quantity of processed products), and, where appropriate, qualitative information such as the temperature of the products (either at the entrance to the enclosure or at the exit depending on where the system is positioned).

Claims (13)

  1. Plant for treating food products of the type comprising an apparatus (10) for cooling food products by bringing the products into contact with a cryogenic fluid, the apparatus being combined with a conveyor (12) for introducing the products into the apparatus and for extracting the said products from the said apparatus (10), the plant furthermore comprising means (20) for detecting the said products (P) treated by the said apparatus (10), these means (20) being suitable for determining a value representative of the quantity and, if required, the quality of the products treated by the said apparatus, the said detection means (20) comprising a camera (22) suitable for producing a digital image of a section (14) of the conveyor (12) intended for transporting the products (P), the said digital image revealing the said products carried by the said section (14) of the conveyor, which camera (22) is connected to a data processing unit (23) comprising image processing means (24) suitable for determining the value representative of the quantity and, if required, the quality of the products (P) treated by the said apparatus from the said digital image, characterized in that it comprises, connected to the said data processing unit (23), means (40) for measuring the quantity of cryogenic fluid with which the products are brought into contact, and the said data processing unit (23) comprises means (24) for computing the temperature of each article (P) leaving the said apparatus (10) according to the value representative of the quantity of products treated and of the quantity of cryogenic fluid measured.
  2. Plant according to Claim 1, characterized in that the said data processing unit (23) comprises means (42) for storing the curve (Γ5) of variation in enthalpy of a product as a function of its temperature, and means (24) for determining the exit temperature of a product from the said enthalpy curve (Γ5), from the quantity of cryogenic fluid measured, from the value representative of the quantity of products treated and from the initial temperature of the products.
  3. Plant according to Claim 1 or 2, characterized in that the line of sight of the said camera (22) extends substantially perpendicular to the plane of movement of the said conveyor (12).
  4. Plant according to one of Claims 1 to 3, characterized in that the said data processing unit (23) comprises means (24) for triggering the taking of an image at predefined triggering times and in that the said image processing means (24) comprise means capable of computing a value representative of the density of products on the conveyor (12) at each triggering time from the said digital image of the said section (14) of the conveyor at this time.
  5. Plant according to Claim 4, characterized in that the said camera is a camera of the monochrome or colour type.
  6. Plant according to Claim 5, characterized in that the said camera is a camera of the colour type and in that the said image processing comprises an analysis of the colours present in the image, enabling, by comparison with a reference colour, the said value representative of the density of products on the conveyor to be determined.
  7. Plant according to one of Claims 4 to 6, characterized in that it comprises means for placing the products (P) on the said conveyor (12) according to a predetermined pattern reproduced sequentially along the said conveyor with a variable quantity of products for each pattern, and in that it comprises, connected to the said data processing unit (23), means (26) for counting the number of patterns travelling past the camera (22), and in that the said data processing unit (23) comprises means (24) for evaluating the value representative of the quantity of products treated from the said value representative of the density of products on the conveyor computed at each triggering time and from the number of patterns counted.
  8. Plant according to Claim 7, characterized in that the said counting means comprise a barrier having at least one optical beam (26), connected to the said data processing unit (23) and placed transversely to the conveyor (12), the beam of the said barrier lying in the plane of movement of the products (P) so as to be interrupted by the products (P) travelling on the conveyor (12).
  9. Plant according to Claim 8, characterized in that the optical barrier (26) comprises, near the conveyor (12), an end (28A) for emitting the said at least one beam and an end (30A) for receiving the said at least one beam and in that these two ends (28A, 30A) are combined with nozzles (38) for ejecting a gas for protecting the said ends, especially a hot gas.
  10. Plant according to Claim 7, characterized in that the said counting means comprise, near the conveyor, an ultrasonic or microwave barrier connected to the said data processing unit and placed transversely to the conveyor, the beam of the said barrier lying in the plane of movement of the products (P) so as to be interrupted by the products (P) travelling on the conveyor.
  11. Plant according to Claim 4, characterized in that the said camera is a camera of the infrared type and in that the said image processing makes it possible to obtain a value representative of the temperature of the products on the conveyor.
  12. Plant according to any one of the preceding claims, characterized in that the said image processing means (24) comprise means for differentiating, in the said image, those areas of the conveyor which are covered by a product (P) from those areas of the conveyor which are left free, as well as means (24) for analysing the said differentiated areas in the said image in order to determine a value representative of the quantity of products (P) treated.
  13. Plant according to Claim 12, characterized in that the said means (24) of analysing the said differentiated areas comprise means (24) of producing, over the entire extent of the image, a first histogram (52A) representative of the number of pixels corresponding to the areas of the conveyor which are covered by a product (P) for each line of the image in the direction (X-X) of movement of the conveyor, means (24) of producing, over the entire extent of the image, a second histogram (54A) representative of the number of pixels corresponding to the areas of the conveyor which are covered by a product (P) for each line of the image in the direction perpendicular to the direction (Y-Y) of movement of the conveyor and means (24) of comparing the values of the peaks of the first and second histograms (52A, 54A) thus produced with first and second threshold values (S1, S2) for determining the density of products (P) treated.
EP98909553A 1997-03-03 1998-02-17 Installation for the treatment of food items Expired - Lifetime EP0965021B1 (en)

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FR9702498A FR2760272B1 (en) 1997-03-03 1997-03-03 ARTICLE PROCESSING INSTALLATION COMPRISING MEANS FOR CHARACTERIZING ARTICLES
FR9702498 1997-03-03
PCT/FR1998/000302 WO1998039606A1 (en) 1997-03-03 1998-02-17 Freezing tunnel

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FR2760272B1 (en) 1999-04-09
ES2180148T3 (en) 2003-02-01
CA2282686A1 (en) 1998-09-11
FR2760272A1 (en) 1998-09-04
DE69806579D1 (en) 2002-08-22
AU6405198A (en) 1998-09-22
WO1998039606A1 (en) 1998-09-11
US6233966B1 (en) 2001-05-22
DE69806579T2 (en) 2003-02-20
AU736830B2 (en) 2001-08-02
EP0965021A1 (en) 1999-12-22

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