WO2020249609A1 - Dispositif de détection de température et moyen de transport - Google Patents

Dispositif de détection de température et moyen de transport Download PDF

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Publication number
WO2020249609A1
WO2020249609A1 PCT/EP2020/066073 EP2020066073W WO2020249609A1 WO 2020249609 A1 WO2020249609 A1 WO 2020249609A1 EP 2020066073 W EP2020066073 W EP 2020066073W WO 2020249609 A1 WO2020249609 A1 WO 2020249609A1
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WO
WIPO (PCT)
Prior art keywords
leaky
wave antenna
detection device
food product
temperature detection
Prior art date
Application number
PCT/EP2020/066073
Other languages
English (en)
Inventor
Michiel Van Rijnbach
Original Assignee
Gea Food Solutions Bakel B.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gea Food Solutions Bakel B.V. filed Critical Gea Food Solutions Bakel B.V.
Publication of WO2020249609A1 publication Critical patent/WO2020249609A1/fr

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
    • G01K11/006—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using measurement of the effect of a material on microwaves or longer electromagnetic waves, e.g. measuring temperature via microwaves emitted by the object
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K2207/00—Application of thermometers in household appliances
    • G01K2207/02—Application of thermometers in household appliances for measuring food temperature
    • G01K2207/06—Application of thermometers in household appliances for measuring food temperature for preparation purposes

Definitions

  • the present invention relates to a temperature detection device for measuring the core temperature of a food product, as well as to a transportation means for conveying a food product comprising a temperature detection device.
  • Temperature detection devices are well known from the state of the art.
  • heat treatment devices such as ovens are used to prepare food in a continuous manner, e.g. with a transportation means in form of a belt system running through an oven on which the food products are placed.
  • Health regulations require those food products to be heated above a predetermined temperature in order to kill pathogenic microorganisms being potentially contained within the food product.
  • the heat treatment device may by design or due to a malfunction comprise a non-uniform temperature distribution.
  • an overheating or overcooking of the food product is undesirable, as it negatively impacts the look, texture and/or the taste of the food product.
  • These cameras have a high lateral resolution, e.g. in the x- and y-direction, but can only measure a surface temperature, which is not a reliable parameter as e.g. an oil film on the food product may have a much higher temperature compared to the temperature at the center of the food product.
  • microwave radiometers for detecting the core temperature, e.g. in EP 2 295 945 A1. Every body emits radiation indicative of its temperature. For the temperatures which are of interest for food production, this radiation is substantially microwave radiation. Hence, by measuring the microwave radiation emitted by a food product, its temperature may be deducted. Therefore, microwave radiometry allows for a non-destructive and non-invasive core
  • phased array antennas such as disclosed e.g. in EP 3 007 559 A1 , have proven to be effective since they allow for the precise manipulation of the effective detection area by varying (electronic) antenna parameters.
  • phased array antennas require complex electronics and shielding means in order to separate the background noise from the radiation emitted by the food product.
  • such antennas are usually placed above the food product, resulting in a high demand for space and a complex installation.
  • the objective is solved with a temperature detection device for measuring the core temperature of a food product, wherein the temperature detection device comprises a leaky-wave antenna, wherein the waveguide of the leaky-wave antenna comprises a spiral shape and wherein the radiation-sensitive and/or radiation-emitting surface of the leaky wave antenna is substantially planar.
  • a leaky-wave antenna is a fast travelling wave antenna comprising a waveguide with openings, wherein the phase velocity of the electromagnetic wave propagating within the waveguide is greater than the speed of light.
  • the openings in the waveguide may be continuous, such as a slotted waveguide, or non-continuous, such as e.g.
  • a planar, spiral-shaped leaky-wave antenna may detect and emit microwave radiation such as used for microwave radiometry in a manner which allows for a very precise core temperature measurement.
  • Planar preferably means in this context that the openings of the waveguide are arranged on a common plane.
  • spiral-shaped preferably means that the leaky-wave antenna comprises a single, continuous waveguide whose openings are arranged in the form of a spiral.
  • the waveguide itself is arranged as a spiral.
  • the planar arrangement of the radiation-sensitive and/or radiation-emitting surface it is advantageously possible to arrange the antenna close to the food product to be measured.
  • the food product is a protein containing substance, in particular meat and/or fish and/or the like. More preferably, the food product is a dairy product and/or a vegetable and/or a fruit and/or the like.
  • the food product may comprise bones or fish-bones. Even more preferably, the food product is processed, such as for example minced, marinated, spiced and/or coated, preferably battered.
  • the food products to be measured comprise substantially the same shape and/or size. More preferably, the shapes and/or sizes of the food products vary.
  • core temperature is preferably to be understood as an average temperature, in particular a weighted average
  • the temperature at the center of the food product is weighted more than the temperatures at the two surfaces of the food product.
  • the core temperature usually does not correspond to a temperature at a specific, in particular one dimensional, point and that the location of the core temperature within a particular food product may vary depending on a plurality of different parameters but will even more preferably approximately correspond to the center of the food product.
  • core temperature is in particular to be understood as to correspond substantially to the temperature at the center of a food product.
  • the measured temperature may as well depend - among other factors - on the thickness of the product and its distance from the heat treatment device.
  • the person skilled in the art understands that following heat treatment, heat continues to propagate through the food product.
  • the highest temperature may be measured at the surface of the food product, at a predetermined distance away from the heat treatment device, the surface of the food product will eventually cool off while the heat may still propagate through the food product mass, resulting in a highest temperature being measured in the bulk of the food product. Therefore, the temperature detection device is preferably
  • the planar surface of the leaky-wave antenna comprises an area of 1000-3000 mm 2 , preferably 1500-2500 mm 2 , in particular 2000 mm 2 .
  • this surface in particular refers to the plane of the waveguide openings.
  • this preferably means that the planar surface is arranged horizontally, wherein planar surface is the uppermost surface of the leaky-wave antenna.
  • a spiral comprises an approximately circular shape
  • the person skilled in the art may deduct that preferably, the diameter of the spiral comprises 20- 80 mm, preferably 30-70 mm, more preferably 40-60 mm, in particular 50 mm. It is herewith advantageously possible to provide an antenna with a relatively small area with which it is possible to create a highly focused and directed and/or directional sensitivity.
  • the waveguide comprises an opening in form of a continuous slot, wherein the slot preferably comprises a width of 1 -3 mm, more preferably 1.5-2.4 mm, in particular 2 mm.
  • the leaky-wave guide preferably comprises a single, continuous waveguide which most preferably comprises at its top a slotted, uninterrupted opening from which a wave may emanate.
  • a slot with the claimed opening width allows for a continuous radiation over the whole length of the spiral-shaped waveguide.
  • this geometry advantageously allows for a manipulation of the antenna parameters such as to create a highly-focused sensitivity pattern of the antenna.
  • the leaky-wave antenna is configured to be rapidly switched between an active mode and a passive mode, wherein in the active mode, the leaky-wave antenna is configured to emit radiation and in the passive mode the leaky-wave antenna is configured to receive radiation.
  • the temperature detection device is configured to detect the reflected part of the radiation emitted in the active mode in order to detect the presence of a food product.
  • the leaky-wave antenna is configured to detect radiation, in particular reflected radiation and/or microwave radiation emitted by the food product, in both the active mode and the passive mode, although, most preferably, at least in the active mode, the radiation emitted by the food product is negligible compared to the reflected radiation.
  • the presence of a food product is detected due to its reflectivity properties. If e.g. a product is above the leaky-wave antenna, its properties, in particular its dielectric properties, e.g. its absorption and/or reflectivity, will change the characteristics of the reflected radiation and in particular the antenna efficiency, therefore advantageously allowing for a food product presence detection.
  • the antenna in the passive mode, the antenna preferably detects the incoming radiation. From the detected microwave radiation, conclusions regarding the temperature of the food product may be drawn. It is therefore herewith advantageously possible to use the temperature detection device not only for measuring the core temperature of the food product, but also to sense and/or detect its presence.
  • the antenna efficiency preferably the antenna efficiency of the near-field and/or far-field radiation, comprises at least one region of highest sensitivity, wherein the region preferably comprises a substantially spherical shape, in particular comprising a diameter of 0.5 cm or 1 cm or 1.5 cm or 2 cm.
  • the region of highest antenna efficiency may preferably alternatively be described as comprising a substantially conical shape, wherein the tip portion may approximately be described as comprising a spherical shape for reasons of simplicity. It is therefore advantageously possible to precisely measure the core temperature of a food product with a high lateral resolution.
  • a spherical shape comprising a certain diameter within the context of the present invention, it is preferably meant that the antenna efficiency outside of this region is significantly lower, in particular about a factor 10 or even more preferably several orders of magnitude lower.
  • the center frequency of the leaky-wave antenna in the passive mode is 2-4 GFIz, preferably 2.5-3.5 GFIz, in particular 3 GFIz, wherein the frequency bandwidth is preferably 200-600 MFIz, more preferably 300-500 MFIz, in particular 400 MFIz, wherein preferably the center frequency of the leaky-wave antenna in the active mode is 2-6 GFIz, preferably 2.5- 4.8 GFIz, in particular 2.8-4.6 GFIz, wherein more preferably the frequency bandwidth of the leaky-wave antenna in the active mode is 1.5-2 GFIz, in particular 1.8 GFIz.
  • the center frequency of the leaky- wave antenna in the passive mode is 3.3 GHz.
  • the temperature detection device comprises at least one, preferably two, temperature sources for calibration, and/or wherein the temperature detection device further comprises a noise source.
  • the temperature source comprises a heating means maintaining a constant temperature. It is herewith advantageously possible to implement a temperature calibration in order to obtain better results and/or to use a noise source for reflection measurements.
  • the temperature detection device will periodically measure the temperature of the at least one temperature source. Thus, via inter-/extrapolation, the temperature of the measured microwave radiation is advantageously determined as exactly as possible.
  • the radiation emitted by the food product is negligible compared to the noise provided by the noise source, such that advantageously, substantially only the reflected radiation and thus in particular the reflectivity of the food product is measured.
  • the measured signal comprises a combination of the antenna efficiency, the equivalent noise temperature of the electronics and the reflectivity of the food product.
  • the leaky-wave antenna is configured to be operated as a total-power radiometer. It is highly advantageous to use a total-power radiometer as it provides for a high sensitivity in case of negligible gain amplifier fluctuations and comprises a relatively simple configuration.
  • Another subject matter of the present invention is a transportation means for transporting a food product along a transportation direction, in particular to and/or from a heat treatment device, comprising a support element supporting a conveying surface, in particular an endless belt, for supporting and transporting the food product and at least one temperature detection device according to the present invention, wherein the temperature detection device is arranged below the conveying surface and is coupled to the support element.
  • the transportation means comprises a drive for moving the conveying surface along a predetermined movement path. More preferably, the transportation means comprises a motor, which most preferably is fixed to the support element.
  • the conveying surface comprises a material which is transparent to the radiation employed by the leaky- wave antenna, wherein preferably the material is polytetrafluoroethylene.
  • the antenna it is herewith advantageously possible for the antenna to be arranged in a space-saving manner underneath the conveying surface without the conveying surface obstructing and/or impacting the radiation, in particular the microwave radiation emitted by the food product.
  • Polytetrafluoroethylene is highly advantageous as a material, because it is substantially transparent in the relevant bandwidth, is heat-resistant, it has a high strength, toughness and self-lubrication properties as well as a good flexibility.
  • the conveying surface consists of the material, at least in the regions where food products are located.
  • the temperature detection device is arranged such that a vertical distance between the radiation- sensitive and/or radiation-emitting surface of the leaky wave antenna and the conveying surface on which the food product is conveyed is 0.01 -10 cm, preferably 0.1 -1 cm. It has surprisingly been found that this distance is optimal as the region of highest antenna efficiency corresponds approximately to a center of a food product placed above the leaky-wave antenna on the conveying surface. Furthermore, with this distance, the leaky-wave antenna advantageously is arranged as close to the food product as possible. In particular, the optimal distance for measuring the core temperature depends on a plurality of factors such as the distance between the food product and the antenna, the thickness of the product and the water content and/or fat content of the product.
  • the support element comprises a preferably planar surface underneath the conveying surface, wherein the planar surface comprises at least one opening at the vertical position of the leaky- wave antenna, wherein the dimensions of the opening substantially correspond to the dimensions of the planar surface of the leaky-wave antenna.
  • a planar surface is a sheet metal.
  • Such a sheet metal enhances the stability of the support element and e.g. may be used to collect parts of food products falling down.
  • the leaky-wave antenna is arranged underneath or in the opening, wherein preferably the opening is covered by a material which is transparent to the radiation employed by the leaky-wave antenna, wherein preferably the material is polytetrafluoroethylene.
  • the leaky-wave antenna is at least partially covered with a material which is transparent to the radiation employed by the leaky-wave antenna, wherein preferably the material is polytetrafluoroethylene.
  • the planar surface of the leaky-wave antenna is covered with a material which is transparent to the radiation employed by the leaky-wave antenna, wherein preferably the material is polytetrafluoroethylene.
  • the transportation means and/or the temperature detection device comprises at least one choke arranged vertically above the leaky-wave antenna.
  • the choke comprises a disc-like and/or annular shape.
  • the choke comprises a disc-like structure circumferentially surrounded by and/or comprising annular structures.
  • the choke is mounted in an opening above the position where food products are located on the conveying surface.
  • the choke is configured such as to minimize the coupling efficiency of the antenna, in particular when no product is present.
  • the transportation means comprises shielding means at least partially surrounding the conveying surface and/or the leaky-wave antenna, wherein the shielding means are configured such that the leaky-wave antenna receives substantially only radiation emitted within the shielding means, e.g. by food products within the shielding means and/or by further elements, such as the leaky-wave antenna, within the shielding means.
  • the shielding means are configured as a Faraday cage.
  • the shielding means comprise a box made of a metallic material, which surrounds the conveying surface and the leaky-wave antenna at the operating location of the temperature detection device.
  • the shielding means comprises at least two slits for allowing the conveying surface and the food product to enter and leave the shielding means.
  • Still a further subject matter of the present invention is a method for measuring a core temperature of a food product using a temperature detection device according to the present invention, wherein in a first step, the food product is transported on the conveying surface of a transportation means, in particular a transportation means according to the present invention, along a transportation direction, wherein in an optional second step, when the food product is located vertically above the leaky- wave antenna, the temperature detection device detects the presence of the food product, wherein in a third step, the temperature detection device detects a core temperature of the food product. It is herewith advantageously possible to precisely measure the core temperature of a food product. Furthermore, detecting the presence of a food product above the leaky-wave antenna advantageously allows for assigning the measured core temperature to that food product.
  • the leaky-wave antenna is rapidly switched between an active mode and a passive mode, wherein in the active mode, the antenna emits radiation, wherein in the passive mode, the antenna detects incoming radiation.
  • the antenna detects incoming radiation in the active mode as well.
  • the reflected signals of the radiation emitted by the antenna are used to detect the presence of the food product, in particular by comparing the reflectivity.
  • the incoming microwave radiation in particular by comparison with reference temperatures, is used to detect the core temperature of the food product.
  • the temperature detection device periodically measures the temperature of at least one temperature source, preferably two temperature sources, wherein the temperature source in particular comprises a heating means maintaining a constant predetermined temperature.
  • the interval between measurements of the temperature source is 1 -10 min, more preferably 3-6 min, in particular 5 min.
  • the measured radiation is compared to the noise provided by a noise source. More preferably, the radiation emitted by the food product is substantially negligible compared to the noise provided by the noise source, such that by comparing, in particular dividing, the measured radiation to the noise provided by the noise source, the reflectivity of the food product is obtained.
  • the antenna efficiency is taken into account as well.
  • Figure 1 shows a perspective view of a leaky-wave antenna according to an embodiment of the present invention.
  • Figure 2 shows a perspective view of a transportation means according to an embodiment of the present invention.
  • Figure 3 shows another perspective view of the transportation means.
  • Figure 4 shows a perspective view of a leaky-wave antenna and a printed circuit board according to an embodiment of the present invention.
  • Figure 5 shows a schematic view of a food product on a conveying surface of a transportation means and a temperature detection device according to an embodiment of the present invention.
  • Figure 6 shows a schematic view of a transportation means according to an embodiment of the present invention.
  • Figure 7a shows a temperature detection device according to an embodiment of the present invention.
  • Figure 7b shows a top view of the surface of a leaky-wave antenna according to an embodiment of the present invention.
  • Figure 8 shows a simulation of the antenna efficiency of a leaky-wave antenna according to an embodiment of the present invention within a food product.
  • Figure 9 shows a perspective detail view of a transportation means according to an embodiment of the present invention.
  • Figure 10 shows a perspective view of a shielding means according to an
  • Figure 11 shows a perspective cross section of a shielding means according to an embodiment of the present invention.
  • Figure 12 shows a schematic electrical diagram of a temperature detection device according to an embodiment of the present invention.
  • Figure 13 shows an exemplary graph of the measurements of a temperature detection device according to an embodiment of the present invention before calibration.
  • Figure 14 shows an exemplary graph of the measurements of a temperature
  • Figure 15 shows a schematic illustration of a transportation means according to an embodiment of the present invention.
  • Figure 16 shows an exemplary graph illustrating the temperature measurement calibration principle of a temperature detection device according to an embodiment of the present invention.
  • Figure 17 shows an exemplary graph with measurements of test objects with a transportation means according to an embodiment of the present invention.
  • FIG. 1 a perspective view of a leaky-wave antenna 1 according to an
  • the leaky-wave antenna 1 comprises a waveguide 2, which is here shown as one piece, but may alternatively also consist of a thin waveguide which is coiled to form a spiral.
  • the waveguide 2 comprises at its top a continuous opening in form of a slot. This opening serves as an exit for emitted radiation and as an entry for incoming radiation.
  • radiation and (electromagnetic) waves may be used
  • a leaky-wave antenna is a travelling-wave type antenna. This means that a wave is electronically fed to a waveguide 2 and subsequently, this wave propagates within the waveguide 2 along its length.
  • a leaky-wave antenna 1 is a fast-wave antenna, which means that within the waveguide 2, the phase velocity of the wave is greater than the speed of light.
  • the waveguide 2 comprises openings. Here, it is a single continuous slot. The incited wave in the waveguide 2 will continuously radiate from the opening and thus lose energy.
  • the radiation pattern of a leaky-wave antenna 1 is determined by the wave which is fed to the waveguide 2 and by the geometrical arrangement of the leaky-wave antenna 1.
  • the opening of the waveguide 2 lies in a plane, i.e. forms a planar surface 3, and the openings are arranged in form of a spiral.
  • the waveguide 2 itself is arranged in a spiral shape.
  • the surface 3 of the leaky-wave antenna comprises a planar surface 3 and the slot, i.e. the opening of the waveguide 2 is spirally arranged.
  • FIG 2 a perspective view of a transportation means 5 according to an
  • the transportation means 5 is here an endless belt conveyor table.
  • the transportation means 5 comprises a support element 6 for support, which in the illustrated case comprises wheels in order to easily move the transportation means 5 to a desired location.
  • the support element 6 comprises a planar surface 7 on top with rounded edges on both sides around which a conveying surface 9, here a belt which is not shown, is moved. Such a surface 7 may be located beneath the conveying surface 9 in order to stabilize the
  • transportation means 5 comprises a drive 8 for moving, i.e. propelling, the conveying surface 9.
  • the surface 7 comprises openings, here four openings 10, below which temperature detection devices are mounted.
  • the temperature detection devices are able to detect the temperature of a food product 4 which is moved by the conveying surface 9 along a transportation direction 100, here e.g. from left to right or the other way around, wherein the food products pass above the openings 10.
  • the transportation means is configured for measuring the temperature of at least two parallel rows of food products and e.g. four food products 4 at the same time, wherein each food product 4 is located over an opening 10 at the time of the measurement.
  • any kind of food product 4 arrangement may be used as well as any kind of opening 10 pattern and therefore any kind of temperature detection device arrangement.
  • FIG 3 another perspective view of the transportation means 5 is shown.
  • the here illustrated embodiment corresponds substantially to the one discussed in conjunction with figure 2. Therefore, it is referred to the above considerations.
  • the leaky-wave antenna 1 substantially corresponds to the one discussed in conjunction with figure 1.
  • the leaky-wave antenna 1 comprises a printed circuit board (PCB) 14.
  • the PCB 14 comprises a main plane of extension which is parallel to the planar surface (3) of the leaky-wave antenna 1.
  • the PCB 14 is arranged at a waveguide transition. Of course, other locations for the PCB 14 are feasible as well.
  • the temperature detection device comprises a master controller, in particular a programmable logic controller (PLC) synchronizing the leaky-wave antennas.
  • PLC programmable logic controller
  • measurement artefacts may be avoided and/or the measurement precision may advantageously be enhanced.
  • the food product 4 comprises a substantially disc-like form, such as e.g. a meat patty.
  • the food product 4 may comprise any other form.
  • the food product is a protein containing substance, in particular meat and/or fish and/or the like.
  • the food product is a dairy product and/or a vegetable and/or a fruit and/or the like.
  • the food product may comprise bones or fish-bones.
  • the food product is processed, such as for example minced, marinated, spiced and/or coated, preferably battered.
  • the food product 4 is located on a conveying surface 9, such as an endless conveyor belt, and is transported along a transportation direction 100.
  • the conveying surface 9 is preferably made from a material which is transparent for the radiation employed by the leaky-wave antenna, i.e. around 2-6 GHz.
  • One such material would e.g. be polytetrafluoroethylene, which has numerous advantages as a conveying material coming into contact with food.
  • the food product 4 will be located right above the leaky wave antenna 1 , as illustrated.
  • the reflectivity measurement of the antenna i.e. in the active mode, is preferably used to determine whether the overlap between the food product and the antenna projection is large enough for a reliable core temperature measurement.
  • the leaky-wave antenna 1 is rapidly switched between an active mode, in which it emits radiation, and a passive mode, in which it detects radiation.
  • the radiation which is emitted in the active mode will transmit the conveying surface 9 and will be reflected by the food product 4.
  • the leaky-wave antenna 1 detects the reflected radiation and in particular compares it with noise provided by a noise source.
  • noise provided by a noise source.
  • the microwave radiation emitted by the food product and being indicative of its temperature is negligible compared to the noise provided by the noise source, by comparing, in particular dividing, the reflected radiation to the noise, the reflectivity of the food product may be deduced. Hence, based upon the reflectivity, the presence of the food product 4 is detected.
  • the microwave radiation of the food product 4 which prior to the currently discussed situation may have been heat treated in a heat-treatment device, such as an oven, is detected.
  • the microwave radiation of the food product 4 is indicative of its temperature.
  • the temperature detection device detects the food product’s 4 microwave radiation and is able to deduct the core temperature of the food product 4. If the core temperature is e.g. too low, the heat-treatment device may be adjusted accordingly and the food product 4 may be discarded as it poses a health risk.
  • the leaky-wave antenna 1 does not only emit radiation in the active mode, but parallel detects incoming radiation as well.
  • the leaky-wave antenna 1 continuously detects radiation and additionally emits radiation in the active mode.
  • the temperature measurement time is about 10-30 ms, in particular 25 ms or 20ms and/or the reflectivity measurement time is about 1-5 ms, in particular 2-4 ms.
  • additional time has to be allotted for the
  • FIG. 6 a schematic view of a transportation means 5 according to an
  • the conveying surface 9 is a revolving endless conveyor belt. A number of food products 4 are being transported by the conveying surface 9 along a transportation direction 100.
  • the temperature detection device comprising a leaky-wave antenna constantly checks for the presence of a food product 4 and/or measures the temperature. When a food product 4 is detected, the measured temperature is assigned to that food product 4.
  • the transportations means 5 comprises shielding means 11 , which in this case are only hinted at here.
  • Such shielding means 11 preferably surround the conveying surface 9 and the temperature detection device and more preferably may be constructed as a Faraday cage.
  • the temperature detection device comprises a substantially planar surface with which it is preferably mounted such beneath the surface 7 of the transportation means that the leaky-wave antenna 1 is arranged in the opening 10 of the surface 7.
  • the surface 3 of the leaky-wave antenna 1 covered by a material which is transparent for the radiation employed by the leaky-wave antenna 1 , e.g. polytetrafluoroethylene and protects the leaky-wave antenna 1 from dirt and/or other contamination.
  • the leaky wave antenna 1 such as illustrated in figure 7b is arranged.
  • the temperature detection device may be located closely underneath the conveying surface 9, such that ultimately, the leaky-wave antenna 1 is distanced only 0.1 -2 cm, in particular only a few millimeters, from the food product 4.
  • the antenna efficiency comprises a substantially conically shaped pattern with a point, or substantially spherical region, of highest sensitivity/ efficiency.
  • This antenna efficiency pattern is obtained by the specific geometry of the leaky-wave antenna 1 as well as by the parameters with which the temperature detection device is operated.
  • the person skilled in the art understand that the antenna efficiency does not comprise hard boundaries, but the here displayed simulation means that outside the illustrated regions, the antenna efficiency is much lower than in the regions, e.g. about a factor 9 or 10, or more preferably even several orders of magnitude lower.
  • the leaky-wave antenna 1 is located such with respect to the food product 4 and the pattern of the antenna efficiency is formed such that the temperature detected by the temperature detection device corresponds to the core temperature of the food product 4.
  • the core temperature will correspond to a (weighted) average temperature distribution within the food product, wherein the temperature at approximately the center of the food will contribute more to the detected temperature distribution.
  • the temperature detection device comprises several, e.g. four, leaky-wave antennas 1 , which are arranged linearly and equidistantly to each other.
  • the temperature detection device comprises chokes 13 for each antenna.
  • Such chokes 13 are used for antenna in order to enhance their directivity and/or for reducing external, non-wanted radiation to reach the antenna. Hence, by including chokes 13, the noise background of the leaky-wave antennas 1 can advantageously be reduced.
  • the chokes 13 are located above the food product 4, i.e. in a vertical axis running through the center of the leaky-wave antenna 1 , the food product 4 is arranged between the leaky-wave antenna 1 and a corresponding choke 13.
  • FIG 10 a perspective view of a shielding means 11 according to an embodiment of the present invention is illustrated.
  • the background noise i.e. the microwave radiation from other sources than the food product 4
  • the transportation means 5 preferably comprises shielding means 11.
  • shielding means 11 in particular acts as a Faraday cage.
  • the shielding means 11 preferably comprises a box-like shape and is more preferably made from metal.
  • the shielding means 11 may comprise substantially the width of the conveying surface 9 and a sufficient height to surround the conveying surface 9 and the temperature detection device or at least one leaky-wave antenna 1.
  • the shielding means 11 comprises two slots through which the conveying surface 9 and the food products may pass.
  • FIG 11 a perspective cross section of a shielding means 11 according to an embodiment of the present invention is illustrated.
  • This embodiment substantially corresponds to the one shown in figure 10, so that reference is made to the above statements.
  • the openings 10 in the support element surface 7 are visible.
  • openings are visible above the openings 10 for the leaky- wave antenna 1.
  • chokes 13 may be mounted for reducing the external noise reaching the leaky-wave antenna 1.
  • the conveying surface 9 runs in the drawing plane between the openings for the chokes 13 and the openings 10 for the leaky-wave antennas 1.
  • a choke 13 is configured such that the corresponding leaky-wave antenna 1 substantially only detects radiation from objects being present in the space between the choke 13 and the leaky-wave antenna 1.
  • FIG 12 a schematic electrical diagram of a temperature detection device according to an embodiment of the present invention is illustrated.
  • the leaky-wave antenna 1 is located.
  • a switch switches between the antenna signal and two temperature reference sources 15, 15’.
  • the temperature sources 15, 15’ comprise heating means maintaining a respective constant, predetermined temperature.
  • a circulator 21 is present in order to ensure that signals from a noise source 16 (the temperature detection device is preferably operated as a total-power radiometer) and a subsequent attenuator 17 only reach the antenna 1 , whereas signals from the leaky-wave antenna 1 only reach the detector 12.
  • the temperature detection device further comprises a low noise amplifier 18, a band pass filter 19 and a gain block 20, which preferably comprises further amplifiers. These elements are well-known elements for antennas as acknowledged by the person skilled in the art, and are therefore not further explained.
  • the detector 12 preferably comprises a differential voltage doubler.
  • the temperature detection device preferably periodically, e.g. every 5 min, measures the temperature of the temperature (reference) sources 15, 15’.
  • the temperature of the measured microwave radiation and thus the core temperature of the food product 4 may be measured.
  • FIG 13 an exemplary graph of the measurements of a temperature detection device according to an embodiment of the present invention before calibration is shown.
  • the temperature calibration according to an embodiment of the present invention may be explained.
  • the leaky-wave antenna 1 does not measure a temperature directly, the signals must be calibrated in order for the temperature detection device to output the correct temperatures.
  • an object with a fixed known temperature is put on the conveyor surface 9 at the position of the leaky-wave antenna 1.
  • a temperature for this incoming radiation is interpolated and/or extrapolated. By comparison of the interpolated temperature with the known temperature of the object, coefficients may be adjusted.
  • FIG 15 a schematic illustration of a transportation means 5 according to an embodiment of the present invention is illustrated.
  • the leaky-wave antenna 1 is located right underneath the conveying surface 9 at the location of the food product 4.
  • a PCB 14 is fixed to the antenna 1 which comprises, among others, temperature references 15.
  • the transportation means 5 further comprises heat conductors, which are the pillar-like structures fixed to the PCB 14.
  • the temperature detection device comprises two temperature references 15, 15’, here denoted as To and Ti.
  • the temperature detection devices comprise a switch switching between the two temperature references 15, 15’ and the antenna 1 signal.
  • the signals lo and h measured at these temperatures can be used to interpolate a linear temperature-signal function. From this function, the temperature at a certain signal which was measured by the leaky-wave antenna 1 may be deducted.
  • the upper curve with the low amplitudes refers to the temperature
  • the leaky-wave antenna 1 is preferably rapidly switched between an active mode and a passive mode.
  • the radiation which was emitted during the active mode and which may be reflected, e.g. by a food product 4 or here a test object, is measured.
  • the radiation is reflected and the measured reflectivity allows the temperature detection device to deduct the presence of a food product 4 or here a test object.
  • the microwave radiation is measured and is indicative of a temperature, in the case of a food object 4 of a core temperature.
  • the background temperature i.e. the temperature of the (reflected) radiation inside the shielding means 11 .
  • the temperature detection device and the transportation means 5 comprising such a temperature detection device obviously work well.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)
  • Radiation Pyrometers (AREA)

Abstract

La présente invention concerne un dispositif de détection de température pour mesurer la température de coeur d'un produit alimentaire, le dispositif comprenant une antenne à ondes de fuite, le guide d'ondes de l'antenne à ondes de fuite comprenant une forme en spirale et la surface sensible au rayonnement et/ou d'émission de rayonnement de l'antenne à ondes de fuite étant sensiblement plane.
PCT/EP2020/066073 2019-06-11 2020-06-10 Dispositif de détection de température et moyen de transport WO2020249609A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP19179425.4 2019-06-11
EP19179425 2019-06-11

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WO2020249609A1 true WO2020249609A1 (fr) 2020-12-17

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5815122A (en) * 1996-01-11 1998-09-29 The Regents Of The University Of Michigan Slot spiral antenna with integrated balun and feed
FR2880122A1 (fr) * 2004-12-23 2006-06-30 Air Liquide Procede et installation de detection de la presence d'un corps
EP2295945A2 (fr) 2009-09-11 2011-03-16 CFS Bakel B.V. Détecteur radiométrique à micro-ondes et dispositif de traitement thermique comportant un tel détecteur
EP3007559A1 (fr) 2013-06-14 2016-04-20 GEA Food Solutions Bakel B.V. Dispositif de détection de température et dispositif de traitement thermique

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5815122A (en) * 1996-01-11 1998-09-29 The Regents Of The University Of Michigan Slot spiral antenna with integrated balun and feed
FR2880122A1 (fr) * 2004-12-23 2006-06-30 Air Liquide Procede et installation de detection de la presence d'un corps
EP2295945A2 (fr) 2009-09-11 2011-03-16 CFS Bakel B.V. Détecteur radiométrique à micro-ondes et dispositif de traitement thermique comportant un tel détecteur
EP3007559A1 (fr) 2013-06-14 2016-04-20 GEA Food Solutions Bakel B.V. Dispositif de détection de température et dispositif de traitement thermique

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