EP2652198A1 - Determination of weight per unit area of a material web using a microwave sensor, the distances between the material web and the surfaces of the microwave sensor being adjusted to a constant value by means of air cushions - Google Patents

Determination of weight per unit area of a material web using a microwave sensor, the distances between the material web and the surfaces of the microwave sensor being adjusted to a constant value by means of air cushions

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Publication number
EP2652198A1
EP2652198A1 EP11790974.7A EP11790974A EP2652198A1 EP 2652198 A1 EP2652198 A1 EP 2652198A1 EP 11790974 A EP11790974 A EP 11790974A EP 2652198 A1 EP2652198 A1 EP 2652198A1
Authority
EP
European Patent Office
Prior art keywords
material web
distance
web
reference element
microwave sensor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP11790974.7A
Other languages
German (de)
French (fr)
Inventor
Thomas Ischdonat
Ingolf Cedra
Oliver Kaufmann
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.)
Voith Patent GmbH
Original Assignee
Voith Patent GmbH
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 Voith Patent GmbH filed Critical Voith Patent GmbH
Publication of EP2652198A1 publication Critical patent/EP2652198A1/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G17/00—Apparatus for or methods of weighing material of special form or property
    • G01G17/02—Apparatus for or methods of weighing material of special form or property for weighing material of filamentary or sheet form
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G9/00—Methods of, or apparatus for, the determination of weight, not provided for in groups G01G1/00 - G01G7/00
    • G01G9/005—Methods of, or apparatus for, the determination of weight, not provided for in groups G01G1/00 - G01G7/00 using radiations, e.g. radioactive
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N22/00—Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/34—Paper
    • G01N33/346—Paper sheets

Definitions

  • the invention relates to a device and a method for determining the weight per unit area of a moving material web, in particular fibrous web, comprising at least one microwave sensor having an element for coupling the microwaves and a reference element, wherein the coupling element and the reference element are spaced apart such that the material web between these is movable.
  • basis weight generally the total weight is e.g. understood a fibrous web, so the weight of all fibrous web components, such as fibers, ashes and water together.
  • the fibrous web may be a paper, tissue or board web.
  • patent application EP 1 703 275 A1 discloses a measuring device and a measuring method and describes a microwave measurement which basically takes this fact into account by measuring the distance and a corresponding signal correction, the measurement results which can be achieved in practice being too inaccurate ,
  • the object of the invention is to provide a device and a method for determining the basis weight of web materials that enables a more accurate basis weight measurement on a moving material web by means of microwave radiation.
  • the device according to the invention comprises at least one microwave sensor having an element for coupling the microwaves and a reference element, wherein at least one microwave sensor element, the coupling element and / or the reference element, is movably arranged, so that the distances between the material web and the elements, for or during the measurement of the moving material web, are adjustable.
  • the setting may e.g. take place by means of mechanical elements, wherein sensor element carrier, on which the micro-sensor elements are mounted, are guided in a carrier element guide parallel to each other movable.
  • the distances are adjusted such that the running material web is held, at least because of the Bernoulli effect, by the dynamic pressure between the microwave sensor element carriers, so that both microwave sensor elements, the coupling element and the reference element, do not come into contact with the material web.
  • the adjustment can be made on a calibration device for the measurement or during the measurement of the running material web.
  • a distance measuring device is preferably provided with which the vertical distance between the mutually parallel Einkoppelele- element and reference element can be measured.
  • a magnetic induction measuring device may be used, although other distance measurements are conceivable, e.g. with an optical measuring method.
  • a control device which regulates the distances between the resonator and the web material and between the reference element and web material, so that the distances can be kept constant to a minimum during the measurement and thus an increased measurement accuracy is achieved.
  • microwave sensor element carriers are kept at a distance from the material web by means of an air bubble and the distances are regulated by changing the air cushion.
  • the distance between the coupling element and the web material and between the reference element and the web material is set or regulated to 1 .mu.m to 10,000 m. The smaller the distance, the better the measurement results.
  • particularly precise distances can be achieved in that at least one microwave sensor element, the coupling element and / or the reference element, by means of a first adjustable or controllable air cushion generated by compressed air in the direction of material web is movable and by means of a second adjustable or controllable air cushion can be kept at a distance from the web.
  • actuators in particular valves, can be used to control the distances with which the air cushion is changed or regulated.
  • a respective microwave resonator is operated in a frequency range of greater than 20 GHz for measuring the basis weight.
  • a respective microwave resonator can be operated in a frequency range of 24 GHz to 24.25 GHz, in particular from 61 GHz to 61, 5 GHz, in particular from 122 GHz to 123 GHz and 244 GHz to 246 GHz.
  • Higher frequencies have the advantage that then the premittivity of water is approximately equal to the premittivity of the other web constituents, e.g. a fibrous web is (see Figure 1).
  • the measurement is preferably carried out with a moving material web by means of a plurality of such distributed over the width of the fibrous web stationary microwave sensors.
  • a moving material web by means of a plurality of such distributed over the width of the fibrous web stationary microwave sensors.
  • at least the basis weight can be measured simultaneously.
  • the measurement of the basis weight in the case of a moving material web takes place by means of at least one microwave sensor traversing the width of the fibrous web.
  • At least one coupling element comprises a planar microwave resonator whose dimensions are of the order of magnitude of the wavelength of the primary radiation used.
  • the individual microwave resonators can be embedded in a ceramic and protected with a coating for protection against contact of the material web.
  • the object mentioned at the outset is also improved by a method for determining the basis weight of a moving material web by means of a method Microwave sensor, comprising a resonator and a reference element, which are spaced apart such that the material web is movable between them, achieved in that the distance between the resonator and web material and between the reference element and web material independently, adjusted for or during the measurement of the moving web is determined and the basis weight by influencing the resonance curve with respect to the set vertical distance between the mutually parallel resonator and reference element.
  • Microwave sensor comprising a resonator and a reference element, which are spaced apart such that the material web is movable between them, achieved in that the distance between the resonator and web material and between the reference element and web material independently, adjusted for or during the measurement of the moving web is determined and the basis weight by influencing the resonance curve with respect to the set vertical distance between the mutually parallel resonator and reference element.
  • the vertical distance between the resonator and the reference element is measured with a distance measuring device.
  • the distance between the resonator and the web material as well as between the reference element and the web material is set to 1 m to 10,000 m.
  • the assignment of the absolute values is preferably done when calibrating the sensor.
  • the distances between the resonator and the web material and between the reference element and web material and / or the distance between the resonator and the reference element are controlled by a control device and the basis weight by influencing the resonance curve with respect to the distance between the coupling element and the reference element measured with the distance measuring device determined.
  • a respective microwave resonator is operated in a frequency range of greater than 20GHz.
  • a respective microwave resonator in a frequency range of 24 GHz to 24.25GHz, in particular from 61 GHz to 61, 5GHz, in particular from 122GHz to 123GHz and 244GHz to 246GHz are operated.
  • the invention will be explained in more detail with reference to drawings.
  • FIG. 2 Diagram: Course of the resonant frequency with respect to FIG.
  • FIG. 1 shows a diagram with the profile of the permittivity of water 1 and fibers 2.
  • the basic physical variable is the permittivity ⁇ ⁇ .
  • the course of the permittivity ⁇ ⁇ of water 1 and that of fibers 2 over a frequency range of (0.1 - 1000) GHz at a temperature of 20 ° C is shown.
  • the permittivity of paper, all components without the water content, is approximately constant over the given frequency range ( ⁇ ⁇ p ap ier ⁇ 4-5). Since the total basis weight is to be measured, the permittivities for all substances contained in the paper, essentially fiber, water and fillers, have to assume approximately the same permittivity value, with the exception of the filler titanium dioxide, the permittivity of the other fillers is negligible.
  • the permittivity ⁇ ⁇ of water depends strongly on the frequency. Only at frequencies> 20 GHz is the permittivity ⁇ ⁇ of water of the same order of magnitude as that of fibers. This is the reason why higher frequencies must be used to measure the total area weight.
  • a suitable method, the permittivity and thus the basis weight too determine is a measurement of the resonant frequency of a microwave resonator.
  • the resonant frequency depends under the above condition, as shown in Fig. 2, in a clear way from the basis weight. The higher the basis weight, the lower the amplitude of the resonance frequency.
  • the decisive factor in this type of measurements is the permittivity of the material to be investigated, with which the resonator interacts.
  • the permittivity determines the frequency and damping behavior of the resonator. Due to the different materials with which the resonator interacts, a shift in the resonant frequency as well as a change in the resonance width result. With greater permittivity, the resonance frequency shifts to lower frequencies as the width of the resonance curve increases.
  • a major disadvantage of the resonance method is that the measured resonance frequency depends very much on the distance of the resonator to the paper. It would be ideal to touch the paper web, but this must be avoided for technological reasons. If the sensor touched the paper web, it would lead to a demolition.
  • FIG. 3 shows a basis weight sensor according to the invention.
  • the sensor consists of a resonator 8 and a reference element 9 which are each arranged on a carrier element 10a, b.
  • the carrier elements 10a, b are guided parallel to one another in a carrier element guide 11a, b in such a way that the distance c between the resonator 8 and the reference element 9 can be changed by the carrier elements being displaced independently.
  • the carrier elements 10a, b are pressed by means of a first air cushion 4 against the material web 6 and by means of a second air cushion 5 ensures that the distance a, b is held to the material web 6, so that a material web 6 between the support elements 10a, b are passed can.
  • the carrier elements 10a, b have corresponding nozzle openings 12 which are supplied with compressed air by a compressed air source.
  • the second air cushion 4 is between support plate 10 a, b and support member 1 1 a, b can be generated, so that the support member 10a, b in a guide the support member 1 1 a, b is displaceable.
  • the air cushions 4, 5 can be conveyed via e.g. Valves (actuators) are controlled such that the distance a, b, c between the resonator 8 and the reference element 9 and / or between the resonator 8 and web material 6 and between the reference element 9 and web material 6 is arbitrarily adjustable.
  • Valves actuators
  • the distances a, b, c can be chosen and regulated differently depending on the paper technology application.
  • the distance c between the resonator 8 and the reference element 9 can be between 1 pm and 10000 pm.
  • a distance measuring device 13 which measures the distance c via magnetic induction, is additionally installed in the carrier element 10a, b.
  • the resonator 8 and the reference element 9 are movably mounted and whose distance a, b can be regulated to the paper web by means of the air cushion and set to a minimum value, and the distance c is measured, ensures that there is no contact with the paper web 6 is coming.
  • FIGS. 4 and 5 show two further embodiments of the device.
  • only the upper support elements 1 1 a are arranged to be movable parallel to the material web.
  • the lower carrier elements 110 are arranged in a fixed position relative to the upper carrier element 11a.
  • the moving web is lifted from the lower microwave sensor element carrier only due to the Bernoulli effect.
  • the control of the distances is carried out by the control of the air cushion 4, 5 by the distance c and the distances a and b can be set or regulated.
  • FIG. 5 10 nozzle openings 12 are present in the lower carrier element.
  • an air cushion 5 can be constructed here, which separates the material web 6 from the carrier element 1 10 lifts off and in conjunction with the air cushions 4, 5, the distances a, b and c are adjustable.

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Abstract

The invention relates to a device for determining the weight per unit area of a moving material web (6), in particular a fibrous material web, said device comprising at least one microwave sensor that has an element for coupling the microwaves (8) and a reference element (9), the coupling element (8) and the reference element (9) being located at a distance from one another in such a way that the material web (6) can be moved therebetween. At least one microwave sensor element, the coupling element (8) and/or the reference element (9) can be moved such that the distances (a, b) between the material web (6) and the elements (8, 9) can be adjusted for or during the measurement of the moving material web.

Description

FLÄCHENGEWICHTSBESTIMMUNG EINER MATERIALBAHN MIT EINEM  SURFACE DETERMINATION OF A MATERIAL RAIL WITH ONE
MIKROWELLENSENSOR, WOBEI DIE ABSTÄNDE ZWISCHEN DER MATERIALBAHN UND DEN OBERFLÄCHEN DES MIKROWELLENSENSORS MIT LUFTKISSEN AUF EINEN KONSTANTEN WERT GEREGELT WERDEN  MICROWAVE SENSOR, WHERE THE DISTANCES BETWEEN THE MATERIAL RAIL AND THE SURFACES OF THE MICROWAVE SENSOR WITH AIR CUSHIONS ARE REGULATED TO A CONSTANT VALUE
Die Erfindung betrifft eine Vorrichtung und ein Verfahren zur Bestimmung des Flächengewichtes einer bewegten Materialbahn, insbesondere Faserstoffbahn, umfassend wenigstens einen Mikrowellensensor, der ein Element zur Einkoppelung der Mikrowellen und ein Referenzelement aufweißt, wobei das Einkoppelelement und das Referenzelement derart voneinander beabstandet sind, dass die Materialbahn zwischen diesen bewegbar ist. Unter Flächengewicht wird allgemein das Gesamtgewicht z.B. einer Faserstoffbahn verstanden, also das Gewicht aller Faserstoffbahnbestandteile, wie Fasern, Asche und Wasser zusammen. The invention relates to a device and a method for determining the weight per unit area of a moving material web, in particular fibrous web, comprising at least one microwave sensor having an element for coupling the microwaves and a reference element, wherein the coupling element and the reference element are spaced apart such that the material web between these is movable. By basis weight, generally the total weight is e.g. understood a fibrous web, so the weight of all fibrous web components, such as fibers, ashes and water together.
Die Faserstoffbahn kann eine Papier-, Tissue- oder Kartonbahn sein. The fibrous web may be a paper, tissue or board web.
Bisherige Messtechniken beruhen meist auf der Absorption gesundheitsgefährden- der radioaktiver Strahlung, so dass eine solche Messung immer mit erheblichen behördlichen Auflagen verbunden ist. Previous measuring techniques are usually based on the absorption of radioactive radiation that endangers health, so that such a measurement is always associated with considerable regulatory requirements.
Eine Möglichkeit dies zu umgehen besteht darin, das Flächengewicht mit hochfrequenter Mikrowellenstrahlung in Absorption und/oder Dispersion (Frequenz > 20 GHz) zu messen. Das grundlegende Messprinzip ist bereits u.a aus der Patentschrift US 4,755,678 von J.R. Izatt et.al. „Simultaneous Measurement of Moisture Content and Basis Weight of Paper Sheet with a submillimeter Laser" oder der Veröffentlichung von E. Nyfors und P. Vainikainen, in „Industrial Microwave Sensors," veröffentlicht von Artech House Norwood 1989 bekannt. Eine Besonderheit solcher Messungen ist, dass das Messsignal einer extremen intrinsischen Abstandsempfindlichkeit unterliegt. One way around this is to measure the basis weight with high-frequency microwave radiation in absorption and / or dispersion (frequency> 20 GHz). The basic measuring principle is already known, inter alia, from US Pat. No. 4,755,678 to JR Izatt et al. "Simultaneous Measurement of Moisture Content and Basis Weight of Paper Sheet with a Sub-millimeter Laser" or the publication by E. Nyfors and P. Vainikainen, in "Industrial Microwave Sensors," published by Artech House Norwood in 1989. A special feature of such measurements is that the measurement signal is subject to an extreme intrinsic distance sensitivity.
So ist in der Patentanmeldung EP 1 703 275 A1 eine Messvorrichtung und ein Messverfahren offenbart und eine Mikrowellenmessung beschrieben, die diesen Sachverhalt zwar grundsätzlich, durch die Messung des Abstands und einer entsprechende Signalkorrektur, berücksichtigt, wobei die so erzielbaren Messergebnisse in der Praxis zu ungenau sind. Thus, patent application EP 1 703 275 A1 discloses a measuring device and a measuring method and describes a microwave measurement which basically takes this fact into account by measuring the distance and a corresponding signal correction, the measurement results which can be achieved in practice being too inaccurate ,
Aufgabe der Erfindung ist es, eine Vorrichtung und ein Verfahren zur Bestimmung des Flächengewichtes von Bahnmaterialien aufzuzeigen, dass eine genauere Flächengewichtmessung an einer bewegten Materialbahn mittels Mikrowellenstrahlung ermöglicht. The object of the invention is to provide a device and a method for determining the basis weight of web materials that enables a more accurate basis weight measurement on a moving material web by means of microwave radiation.
Die Aufgabe wird mittels einer Vorrichtung mit den Merkmalen des Anspruches 1 sowie dem Verfahren nach Anspruch 10 gelöst. The object is achieved by means of a device having the features of claim 1 and the method according to claim 10.
Die erfindungsgemäße Vorrichtung umfasst wenigstens einen Mikrowellensensor, der ein Element zur Einkoppelung der Mikrowellen und ein Referenzelement aufweist, wobei mindestens ein Mikrowellensensorelement, das Einkoppelelement und/oder das Referenzelement, beweglich angeordnet ist, so dass die Abstände zwischen der Materialbahn und den Elementen, für oder während der Messung der bewegten Materialbahn, einstellbar sind. Die Einstellung kann z.B. mittels mechanischer Elemente erfolgen, wobei Sensorelementträger, auf denen die Mikrosensorelemente befestigt sind, in einer Trägerelementführung zueinander parallel beweglich geführt sind. The device according to the invention comprises at least one microwave sensor having an element for coupling the microwaves and a reference element, wherein at least one microwave sensor element, the coupling element and / or the reference element, is movably arranged, so that the distances between the material web and the elements, for or during the measurement of the moving material web, are adjustable. The setting may e.g. take place by means of mechanical elements, wherein sensor element carrier, on which the micro-sensor elements are mounted, are guided in a carrier element guide parallel to each other movable.
Der Abstände werden derart eingestellt, dass die laufende Materialbahn zumindest aufgrund des Bernoulli-Effekts, durch den dynamischen Druck, zwischen den Mikrowellensensorelementträgern gehalten wird, so dass beide Mikrowellensensorelemente, das Einkoppelelement und das Referenzelement, nicht mit der Materialbahn in Berührung kommen. Die Einstellung kann dabei auf einer Kalibriervorrichtung für die Messung oder während der Messung der laufenden Materialbahn erfolgen. The distances are adjusted such that the running material web is held, at least because of the Bernoulli effect, by the dynamic pressure between the microwave sensor element carriers, so that both microwave sensor elements, the coupling element and the reference element, do not come into contact with the material web. The adjustment can be made on a calibration device for the measurement or during the measurement of the running material web.
Bevorzugt ist zusätzlich eine Abstandsmessvorrichtung vorhanden, mit der der senkrechte Abstand zwischen den zueinander parallel angeordneten Einkoppelele- ment und Referenzelement messbar ist. In addition, a distance measuring device is preferably provided with which the vertical distance between the mutually parallel Einkoppelele- element and reference element can be measured.
Zur Abstandsmessung kann eine magnetische Induktionsmessvorrichtung verwendet werden, wobei auch andere Abstandsmessungen denkbar sind, z.B. mit einem optischen Messverfahren. For distance measurement, a magnetic induction measuring device may be used, although other distance measurements are conceivable, e.g. with an optical measuring method.
Des Weiteren ist es besonders vorteilhaft, wenn eine Regelvorrichtung vorhanden ist, die die Abstände zwischen Resonator und Bahnmaterial sowie zwischen Referenzelement und Bahnmaterial regelt, so dass während der Messung die Abstände konstant auf ein Minimum gehalten werden können und so eine erhöhte Messgenauigkeit erreicht wird. Furthermore, it is particularly advantageous if a control device is provided which regulates the distances between the resonator and the web material and between the reference element and web material, so that the distances can be kept constant to a minimum during the measurement and thus an increased measurement accuracy is achieved.
Von Vorteil ist es, wenn die Mikrowellensensorelementträger mittels eines Luftkis- sens auf Abstand zur Materialbahn gehalten werden und die Abstände durch Veränderung des Luftkissens geregelt werden. It is advantageous if the microwave sensor element carriers are kept at a distance from the material web by means of an air bubble and the distances are regulated by changing the air cushion.
Gemäß einer bevorzugten praktischen Ausbildung wird der Abstand zwischen Einkoppelelement und Bahnmaterial sowie zwischen Referenzelement und Bahnmaterial auf 1 pm bis 10000 m eingestellt bzw. geregelt. Je geringer der Abstand, desto besser die Messergebnisse. According to a preferred practical embodiment, the distance between the coupling element and the web material and between the reference element and the web material is set or regulated to 1 .mu.m to 10,000 m. The smaller the distance, the better the measurement results.
In einer weiteren Ausführung können besonders genaue Abstände dadurch erreicht werden, dass mindestens ein Mikrowellensensorelement, das Einkoppelelement und/oder das Referenzelement, mittels eines, durch Druckluft erzeugten, ersten einstellbaren oder regelbaren Luftkissens in Richtung Materialbahn bewegbar ist und mittels eines zweiten einstellbaren oder regelbaren Luftkissens gegenüber der Materialbahn auf Abstand gehalten werden kann. In a further embodiment, particularly precise distances can be achieved in that at least one microwave sensor element, the coupling element and / or the reference element, by means of a first adjustable or controllable air cushion generated by compressed air in the direction of material web is movable and by means of a second adjustable or controllable air cushion can be kept at a distance from the web.
Durch diese flexible Aufhängung können insbesondere Materialdickenänderungen ausgeglichen werden, insbesondere bei minimalen Abständen zur Materialbahn. Due to this flexible suspension in particular material thickness changes be compensated, especially at minimum distances to the web.
So können zur Regelung der Abstände Aktuatoren, insbesondere Ventile, verwendet werden, mit denen das Luftkissen verändert bzw. geregelt wird. Thus, actuators, in particular valves, can be used to control the distances with which the air cushion is changed or regulated.
Bevorzugt wird zur Messung des Flächengewichtes ein betreffender Mikrowellenre- sonator in einem Frequenzbereich von größer 20Ghz betrieben. Preferably, a respective microwave resonator is operated in a frequency range of greater than 20 GHz for measuring the basis weight.
Des Weiteren kann zur Messung des Flächengewichtes ein betreffender Mikrowellenresonator in einem Frequenzbereich von 24 GHz bis 24,25GHz, insbesondere von 61 GHz bis 61 ,5GHz, insbesondere von 122GHz bis 123GHz und 244GHz bis 246GHz betrieben werden. Höhere Frequenzen haben den Vorteil, dass dann die Premittivität von Wasser annähernd gleich der Premittivität der anderen Materialbahnbestandteile z.B. einer Faserstoffbahn ist (siehe Figur 1 ). Furthermore, for measuring the basis weight, a respective microwave resonator can be operated in a frequency range of 24 GHz to 24.25 GHz, in particular from 61 GHz to 61, 5 GHz, in particular from 122 GHz to 123 GHz and 244 GHz to 246 GHz. Higher frequencies have the advantage that then the premittivity of water is approximately equal to the premittivity of the other web constituents, e.g. a fibrous web is (see Figure 1).
Die Messung erfolgt bevorzugt bei bewegter Materialbahn mittels mehrerer solcher über die Breite der Faserstoffbahn verteilter stationärer Mikrowellensensoren. Dabei kann über die Mehrzahl der über die Breite der Faserstoffbahn verteilten stationären Mikrowellensensoren vorteilhafterweise zumindest das Flächengewicht simultan gemessen werden. Alternativ oder ergänzend erfolgt die Messung des Flächengewichts bei bewegter Materialbahn mittels mindestens eines über die Breite der Faserstoffbahn traversierenden Mikrowellensensors. The measurement is preferably carried out with a moving material web by means of a plurality of such distributed over the width of the fibrous web stationary microwave sensors. In this case, over the majority of the distributed across the width of the fibrous web stationary microwave sensors advantageously at least the basis weight can be measured simultaneously. Alternatively or additionally, the measurement of the basis weight in the case of a moving material web takes place by means of at least one microwave sensor traversing the width of the fibrous web.
Gemäß einer bevorzugten praktischen Ausführungsform der erfindungsgemäßen Vorrichtung umfasst zumindest ein Einkoppelelement einen planaren Mikrowellenresonator, dessen Abmessungen in der Größenordnung der Wellenlänge der verwendeten Primärstrahlung liegen. According to a preferred practical embodiment of the device according to the invention, at least one coupling element comprises a planar microwave resonator whose dimensions are of the order of magnitude of the wavelength of the primary radiation used.
Die einzelnen Mikrowellenresonatoren können in eine Keramik eingebettet sein und zum Schutz gegen Berührungen der Materialbahn mit einer Beschichtung geschützt werden. The individual microwave resonators can be embedded in a ceramic and protected with a coating for protection against contact of the material web.
Erfindungsgemäß wird die Eingangs genannte Aufgabe zudem durch ein Verfahren zur Bestimmung des Flächengewichtes einer bewegten Materialbahn mittels eines Mikrowellensensors, umfassend einen Resonator und ein Referenzelement, die derart voneinander beabstandet sind, dass die Materialbahn zwischen diesen bewegbar ist, dadurch gelöst, dass der Abstand zwischen Resonator und Bahnmaterial sowie zwischen Referenzelement und Bahnmaterial unabhängig voneinander, für oder während der Messung der bewegten Materialbahn eingestellt wird und das Flächengewicht durch die Beeinflussung der Resonanzkurve in Bezug auf den eingestellten senkrechten Abstand zwischen den parallel zueinander angeordneten Resonator und Referenzelement ermittelt wird. According to the invention, the object mentioned at the outset is also improved by a method for determining the basis weight of a moving material web by means of a method Microwave sensor, comprising a resonator and a reference element, which are spaced apart such that the material web is movable between them, achieved in that the distance between the resonator and web material and between the reference element and web material independently, adjusted for or during the measurement of the moving web is determined and the basis weight by influencing the resonance curve with respect to the set vertical distance between the mutually parallel resonator and reference element.
Gemäß einer bevorzugten praktischen Ausgestaltung des erfindungsgemäßen Verfahrens wird mit einer Abstandsmessvorrichtung der senkrechte Abstand zwischen Resonator und Referenzelement gemessen. According to a preferred practical embodiment of the method according to the invention, the vertical distance between the resonator and the reference element is measured with a distance measuring device.
Bevorzugt wird der Abstand zwischen Resonator und Bahnmaterial sowie zwischen Referenzelement und Bahnmaterial auf 1 m bis 10000 m eingestellt. Die Zuordnung der Absolutwerte geschieht vorzugsweise beim Kalibrieren des Sensors. Weiterhin bevorzugt werden die Abstände zwischen Resonator und Bahnmaterial sowie zwischen Referenzelement und Bahnmaterial und/oder der Abstand zwischen Resonator und Referenzelement mit einer Regelvorrichtung geregelt und das Flächengewicht durch die Beeinflussung der Resonanzkurve in Bezug auf den, mit der Abstandsmessvorrichtung, gemessenen Abstand zwischen Einkoppelelement und Referenzelement ermittelt. Preferably, the distance between the resonator and the web material as well as between the reference element and the web material is set to 1 m to 10,000 m. The assignment of the absolute values is preferably done when calibrating the sensor. Further preferably, the distances between the resonator and the web material and between the reference element and web material and / or the distance between the resonator and the reference element are controlled by a control device and the basis weight by influencing the resonance curve with respect to the distance between the coupling element and the reference element measured with the distance measuring device determined.
Zur Messung des Flächengewichtes wird ein betreffender Mikrowellenresonator in einem Frequenzbereich von größer 20GHz betrieben. To measure the basis weight, a respective microwave resonator is operated in a frequency range of greater than 20GHz.
Weiterhin kann zur Messung des Flächengewichtes ein betreffender Mikrowellenresonator in einem Frequenzbereich von 24 GHz bis 24,25GHz, insbesondere von 61 GHz bis 61 ,5GHz, insbesondere von 122GHz bis 123GHz und 244GHz bis 246GHz betrieben werden. Nachfolgend wird die Erfindung anhand von Skizzen näher erläutert. Furthermore, for measuring the basis weight, a respective microwave resonator in a frequency range of 24 GHz to 24.25GHz, in particular from 61 GHz to 61, 5GHz, in particular from 122GHz to 123GHz and 244GHz to 246GHz are operated. The invention will be explained in more detail with reference to drawings.
In diesen zeigen: In these show:
Figur 1 Diagramm: Verlauf der Permittivität von Wasser und Fasern  Figure 1 Diagram: Course of the permittivity of water and fibers
Figur 2 Diagramm: Verlauf der Resonanzfrequenz in Bezug auf das FIG. 2 Diagram: Course of the resonant frequency with respect to FIG
Flächengewicht.  Grammage.
Figur 3 erfindungsgemäßer Flächengewichtssensor  Figure 3 inventive basis weight sensor
Figur 1 zeigt ein Diagramm mit dem Verlauf der Permittivität von Wasser 1 und Fasern 2. Bei Messungen mit Mikrowellen ist die grundlegende physikalische Größe die Permittivität εΓ. So ist der Verlauf der Permittivität εΓ von Wasser 1 und diejenige von Fasern 2 über einen Frequenzbereich von (0.1 - 1000) GHz bei einer Temperatur von 20°C dargestellt. FIG. 1 shows a diagram with the profile of the permittivity of water 1 and fibers 2. In the case of measurements with microwaves, the basic physical variable is the permittivity ε Γ . Thus, the course of the permittivity ε Γ of water 1 and that of fibers 2 over a frequency range of (0.1 - 1000) GHz at a temperature of 20 ° C is shown.
Die Permittivität von Papier, alle Bestandteile ohne den Wasseranteil, ist über den gegebenen Frequenzbereich annähernd konstant (εΓ papier ~ 4-5). Da das gesamte Flächengewicht gemessen werden soll, müssen die Permittivitäten für alle im Papier enthaltenen Substanzen, im Wesentlichen Faser, Wasser und Füllstoffe, annähernd den gleichen Permittivitätswert annehmen, wobei mit Ausnahme des Füllstoffes Titandioxid, die Permittivität der anderen Füllstoffe vernachlässigbar ist. The permittivity of paper, all components without the water content, is approximately constant over the given frequency range (ε Γ p ap ier ~ 4-5). Since the total basis weight is to be measured, the permittivities for all substances contained in the paper, essentially fiber, water and fillers, have to assume approximately the same permittivity value, with the exception of the filler titanium dioxide, the permittivity of the other fillers is negligible.
Wie aus der Kurve für Wasser ersichtlich ist, hängt die Permittivität εΓ von Wasser jedoch stark von der Frequenz ab. Erst ab Frequenzen > 20 GHz liegt die Permittivi- tät εΓ von Wasser in derselben Größenordnung wie diejenige von Fasern. Dies ist der Grund, weshalb für die Messung des Gesamtflächengewichts höhere Frequenzen verwendet werden müssen. As can be seen from the curve for water, the permittivity ε Γ of water, however, depends strongly on the frequency. Only at frequencies> 20 GHz is the permittivity ε Γ of water of the same order of magnitude as that of fibers. This is the reason why higher frequencies must be used to measure the total area weight.
Zur Messung des Flächengewichts ist es somit erforderlich, einen Frequenzbereich aufzufinden, in dem alle in der Faserstoffbahn beziehungsweise im Papier vorkom- menden Inhaltsstoffe eine mehr oder weniger gleiche Permittivität besitzen. Damit ist gewährleistet, dass die Faserstoffbahn beziehungsweise das Papier als einheitliches Messgut betrachtet werden kann. Dieser Messbereich liegt in Frequenzbereichen größer 20 GHz und insbesondere in Frequenzbereichen größer 100 GHz. In order to measure the weight per unit area, it is thus necessary to find a frequency range in which all constituents present in the fibrous web or in the paper have a more or less equal permittivity. This ensures that the fibrous web or the paper can be regarded as a uniform material to be measured. This measuring range is in frequency ranges greater than 20 GHz and in particular in frequency ranges greater than 100 GHz.
Eine geeignete Methode, die Permittivität und somit das Flächengewicht zu bestimmen, ist eine Vermessung der Resonanzfrequenz eines Mikrowellenresonators. Die Resonanzfrequenz hängt unter obiger Bedingung, wie aus Fig. 2 zu entnehmen, in eindeutiger Weise vom Flächengewicht ab. Je höher das Flächengewicht ist, desto niedriger ist die Amplitude der Resonanzfrequenz. Die entscheidende Größe bei dieser Art von Messungen ist die Permittivität des jeweils zu untersuchenden Materials, mit dem der Resonator zusammenwirkt. Die Permittivität bestimmt das Frequenz- und Dämpfungsverhalten des Resonators. Dabei ergeben sich durch die unterschiedlichen Materialien, mit denen der Resonator zusammenwirkt, eine Verschiebung der Resonanzfrequenz sowie eine Änderung der Resonanzbreite. Bei größerer Permittivität verschiebt sich die Resonanzfrequenz zu niedrigeren Frequenzen, während die Breite der Resonanzkurve zunimmt. A suitable method, the permittivity and thus the basis weight too determine is a measurement of the resonant frequency of a microwave resonator. The resonant frequency depends under the above condition, as shown in Fig. 2, in a clear way from the basis weight. The higher the basis weight, the lower the amplitude of the resonance frequency. The decisive factor in this type of measurements is the permittivity of the material to be investigated, with which the resonator interacts. The permittivity determines the frequency and damping behavior of the resonator. Due to the different materials with which the resonator interacts, a shift in the resonant frequency as well as a change in the resonance width result. With greater permittivity, the resonance frequency shifts to lower frequencies as the width of the resonance curve increases.
Ein großer Nachteil der Resonanzmethode ist, dass die gemessene Resonanzfrequenz sehr stark vom Abstand des Resonators zum Papier abhängt. Ideal wäre eine Berührung der Papierbahn, was jedoch aus technologischen Gründen zwin- gend zu vermeiden ist. Würde der Sensor die Papierbahn berühren, würde es zu einem Abriss kommen. A major disadvantage of the resonance method is that the measured resonance frequency depends very much on the distance of the resonator to the paper. It would be ideal to touch the paper web, but this must be avoided for technological reasons. If the sensor touched the paper web, it would lead to a demolition.
In Figur 3 ist ein erfindungsgemäßer Flächengewichtssensor dargestellt. Der Sensor besteht aus einem Resonator 8 und einem Referenzelement 9 die jeweils auf einem Trägerelement 10a, b angeordnet sind. Die Trägerelemente 10a, b sind in einer Trägerelementführung 1 1 a, b derart parallel zueinander geführt, dass der Abstand c zwischen Resonator 8 und Referenzelement 9 durch das unabhängig verschieben der Trägerelemente veränderbar ist. FIG. 3 shows a basis weight sensor according to the invention. The sensor consists of a resonator 8 and a reference element 9 which are each arranged on a carrier element 10a, b. The carrier elements 10a, b are guided parallel to one another in a carrier element guide 11a, b in such a way that the distance c between the resonator 8 and the reference element 9 can be changed by the carrier elements being displaced independently.
Die Trägerelemente 10a, b werden mittels eines ersten Luftkissens 4 gegen die Materialbahn 6 gedrückt und mittels eines zweiten Luftkissens 5 wird sichergestellt, dass der Abstand a, b zur Materialbahn 6 gehalten wird, so dass eine Materialbahn 6 zwischen den Trägerelementen 10a, b hindurchgeführt werden kann. The carrier elements 10a, b are pressed by means of a first air cushion 4 against the material web 6 and by means of a second air cushion 5 ensures that the distance a, b is held to the material web 6, so that a material web 6 between the support elements 10a, b are passed can.
Zur Erzeugung des Luftkissens 5 weisen die Trägerelemente 10a, b entsprechende Düsenöffnungen 12 auf, die von einer Druckluftquelle mit Druckluft versorgt werden. Das zweite Luftkissen 4 ist zwischen Trägerplatte 10a, b und Trägerelement 1 1 a, b erzeugbar, so dass das Trägerelement 10a, b in einer Führung den Trägerelements 1 1 a, b verschiebbar ist. To produce the air cushion 5, the carrier elements 10a, b have corresponding nozzle openings 12 which are supplied with compressed air by a compressed air source. The second air cushion 4 is between support plate 10 a, b and support member 1 1 a, b can be generated, so that the support member 10a, b in a guide the support member 1 1 a, b is displaceable.
Die Luftkissen 4, 5 können über z.B. Ventile (Aktuatoren) derart geregelt werden, dass der Abstand a, b, c zwischen dem Resonator 8 und dem Referenzelement 9 und/oder zwischen Resonator 8 und Bahnmaterial 6 sowie zwischen Referenzelement 9 und Bahnmaterial 6 beliebig einstellbar ist. So können die Abstände a, b, c je nach papiertechnologischer Anwendung unterschiedlich gewählt und geregelt werden. The air cushions 4, 5 can be conveyed via e.g. Valves (actuators) are controlled such that the distance a, b, c between the resonator 8 and the reference element 9 and / or between the resonator 8 and web material 6 and between the reference element 9 and web material 6 is arbitrarily adjustable. Thus, the distances a, b, c can be chosen and regulated differently depending on the paper technology application.
Der Abstand c zwischen dem Resonator 8 und dem Referenzelement 9 kann zwischen 1 pm und 10000 pm liegen. Zur Messung des Abstandes ist in dem Trägerelement 10a, b zusätzlich eine Abstandsmessvorrichtung 13 eingebaut, die über magnetische Induktion den Abstand c misst. The distance c between the resonator 8 and the reference element 9 can be between 1 pm and 10000 pm. In order to measure the distance, a distance measuring device 13, which measures the distance c via magnetic induction, is additionally installed in the carrier element 10a, b.
Dadurch dass der Resonator 8 und das Referenzelement 9 beweglich gelagert sind und deren Abstand a, b zur Papierbahn mittels der Luftpolster geregelt und auf einen Minimalwert eingestellt werden kann, sowie der Abstand c gemessen wird, ist sichergestellt, dass es zu keiner Berührung mit der Papierbahn 6 kommt. The fact that the resonator 8 and the reference element 9 are movably mounted and whose distance a, b can be regulated to the paper web by means of the air cushion and set to a minimum value, and the distance c is measured, ensures that there is no contact with the paper web 6 is coming.
In Fig. 4 und 5 sind zwei weitere Ausführungsformen der Vorrichtung gezeigt. In diesen Ausführungsformen sind nur die oberen Trägerelemente 1 1 a parallel zur Materialbahn beweglich angeordnet. Die unteren Trägerelemente 1 10 sind gegen- über dem oberen Trägerelement 1 1 a in einer fixen Position angeordnet. FIGS. 4 and 5 show two further embodiments of the device. In these embodiments, only the upper support elements 1 1 a are arranged to be movable parallel to the material web. The lower carrier elements 110 are arranged in a fixed position relative to the upper carrier element 11a.
So wird bei der in Fig. 4 gezeigten Ausführung die bewegte Materialbahn nur aufgrund des Bernoulli-Effekts von dem unteren Mikrowellensensorelementträger abgehoben. Die Regelung der Abstände erfolgt durch die Regelung der Luftpolster 4, 5 durch die der Abstand c sowie die Abstände a und b eingestellt bzw. geregelt werden können. Thus, in the embodiment shown in Fig. 4, the moving web is lifted from the lower microwave sensor element carrier only due to the Bernoulli effect. The control of the distances is carried out by the control of the air cushion 4, 5 by the distance c and the distances a and b can be set or regulated.
Der Unterschied zwischen den Ausführungen in Fig.4 und Fig. 5 ist, dass in Figur 5 in dem unteren Trägerelement 1 10 Düsenöffnungen 12 vorhanden sind. So kann hier ein Luftpolster 5 aufgebaut werden, das die Materialbahn 6 von dem Träger- element 1 10 abhebt und im Zusammenspiel mit den Luftpolstern 4, 5 die Abstände a, b und c regelbar sind. The difference between the embodiments in FIG. 4 and FIG. 5 is that in FIG. 5 10 nozzle openings 12 are present in the lower carrier element. Thus, an air cushion 5 can be constructed here, which separates the material web 6 from the carrier element 1 10 lifts off and in conjunction with the air cushions 4, 5, the distances a, b and c are adjustable.
Bezugszeichenliste LIST OF REFERENCE NUMBERS
1 Permittivität von Wasser1 Permittivity of water
2 Permittivität von Fasern2 Permittivity of fibers
3 Basisgewichtsänderung3 basis weight change
4 erste Luftkissen 4 first air cushions
5 zweite Luftkissen 5 second air cushions
6 Papierbahn 6 paper web
7 Mikrowelle  7 microwave
8 Einkoppelelement 8 coupling element
9 Referenzelement9 reference element
10 Trägerelement 10 carrier element
1 1 Trägerelementführung 1 1 carrier element guide
12 Düsenöffnungen 12 nozzle openings
13 Abstandsmessmittel 13 distance measuring means
1 10 Trägerelement a/b Abstand 1 10 carrier element a / b distance
c Abstand c distance

Claims

Patentansprüche claims
Vorrichtung zur Bestimmung des Flächengewichtes einer bewegten Materialbahn (6), insbesondere Faserstoffbahn, umfassend wenigstens einen Mikrowellensensor, der ein Element zur Einkoppelung der Mikrowellen (8) und ein Referenzelement (9) aufweist, wobei das Einkoppelelement (8) und das Referenzelement (9) derart voneinander beabstandet sind, dass die Materialbahn (6) zwischen diesen bewegbar ist, Device for determining the basis weight of a moving material web (6), in particular fibrous web, comprising at least one microwave sensor having an element for coupling the microwaves (8) and a reference element (9), wherein the coupling element (8) and the reference element (9) are spaced apart such that the material web (6) is movable between them,
dadurch gekennzeichnet,  characterized,
dass mindestens ein Mikrowellensensorelement, das Einkoppelelement (8) und/oder das Referenzelement (9), beweglich angeordnet ist, so dass die jeweiligen Abstände (a, b) zwischen der Materialbahn (6) und den Elementen (8, 9), für oder während der Messung der bewegten Materialbahn, einstellbar sind.  in that at least one microwave sensor element, the coupling element (8) and / or the reference element (9), is movably arranged so that the respective distances (a, b) between the material web (6) and the elements (8, 9), for or during the measurement of the moving material web, are adjustable.
Vorrichtung nach Anspruch 1 , Device according to claim 1,
dadurch gekennzeichnet,  characterized,
dass eine Abstandsmessvorrichtung (13) vorhanden ist, mit der der senkrechte Abstand (c) zwischen den zueinander parallel angeordneten Einkoppelelement (8) und Referenzelement (9) messbar ist.  a distance measuring device (13) is provided with which the vertical distance (c) between the coupling element (8) and the reference element (9) arranged parallel to one another can be measured.
Vorrichtung nach Anspruch 2, Device according to claim 2,
dadurch gekennzeichnet,  characterized,
dass die Abstandsmessvorrichtung (13) eine magnetische Induktionsmessvorrichtung ist.  in that the distance measuring device (13) is a magnetic induction measuring device.
4. Vorrichtung nach Anspruch 1 , 4. Apparatus according to claim 1,
dadurch gekennzeichnet,  characterized,
dass der Abstand (a, b) zwischen der Materialbahn (6) und den Elementen (8, 9) mittels einer Regelung, während der Messung der bewegten Materialbahn, regelbar ist. the distance (a, b) between the material web (6) and the elements (8, 9) can be regulated by means of regulation during the measurement of the moving material web.
5. Vorrichtung nach Anspruch 1 oder 4, 5. Apparatus according to claim 1 or 4,
dadurch gekennzeichnet,  characterized,
dass der Abstand (a, b) zwischen Einkoppelelement (8) und Bahnmaterial (6) sowie zwischen Referenzelement (9) und Bahnmaterial (6) auf 1 pm bis l OOOOpm eingestellt oder regelbar ist.  the distance (a, b) between the coupling element (8) and the web material (6) and between the reference element (9) and the web material (6) is set or controllable to 1 μm to 10 000 rpm.
6. Vorrichtung nach einem der Ansprüche 1 bis 5, 6. Device according to one of claims 1 to 5,
dadurch gekennzeichnet,  characterized,
dass mindestens ein Mikrowellensensorelement, das Einkoppelelement (8) und/oder das Referenzelement (9), mittels eines, durch Druckluft erzeugten, ersten einstellbaren oder regelbaren Luftkissens (4) in Richtung Materialbahn bewegbar ist und mittels eines zweiten einstellbaren oder regelbaren Luftkissens (5) gegenüber der Materialbahn (6) auf Abstand gehalten werden kann.  in that at least one microwave sensor element, the coupling element (8) and / or the reference element (9), is movable towards the material web by means of a first adjustable or controllable air cushion (4) generated by compressed air and by means of a second adjustable or controllable air cushion (5). opposite to the material web (6) can be kept at a distance.
7. Vorrichtung nach einem der Ansprüche 1 bis 5, 7. Device according to one of claims 1 to 5,
dadurch gekennzeichnet,  characterized,
dass zur Regelung der Abstände (a, b, c) Aktuatoren, insbesondere Ventile, verwendet werden.  in that actuators, in particular valves, are used to control the distances (a, b, c).
8. Vorrichtung nach Anspruch 1 , 8. Apparatus according to claim 1,
dadurch gekennzeichnet,  characterized,
dass zur Messung des Flächengewichtes ein betreffender Mikrowellenresonator (8) in einem Frequenzbereich von größer 20 GHz betreibbar ist.  in that for measuring the basis weight a respective microwave resonator (8) can be operated in a frequency range of greater than 20 GHz.
9. Verfahren zur Bestimmung des Flächengewichtes einer bewegten Materialbahn (6), insbesondere Faserstoffbahn, aufweisend wenigstens einen Mikrowellensensor, der ein Element zur Einkoppelung der Mikrowellen (8) und ein Referenzelement (9) aufweist, wobei das Einkoppelelement (8) und das Referenzelement (9) derart voneinander beabstandet sind, dass die Materialbahn (6) zwischen diesen bewegbar ist, 9. A method for determining the basis weight of a moving material web (6), in particular fibrous web, comprising at least one microwave sensor having an element for coupling the microwaves (8) and a reference element (9), wherein the coupling element (8) and the reference element ( 9) are spaced apart such that the material web (6) is movable between them,
dadurch gekennzeichnet, dass mindestens ein Mikrowellensensorelement (8, 9), das Einkoppelelementcharacterized, in that at least one microwave sensor element (8, 9), the coupling element
(8) und/oder das Referenzelement (9), beweglich angeordnet ist und die Abstände (a, b) zwischen der Materialbahn (6) und den Elementen (8, 9) für oder während der Messung der bewegten Materialbahn (6), auf einen Wert eingestellt werden und das Flächengewicht durch die Beeinflussung der Resonanzkurve in Bezug auf den eingestellten senkrechten Abstand (c) zwischen den parallel angeordneten Einkoppelelement (8) und Referenzelement(8) and / or the reference element (9) is arranged to be movable and the distances (a, b) between the material web (6) and the elements (8, 9) for or during the measurement of the moving material web (6) a value can be adjusted and the surface weight by influencing the resonance curve with respect to the set vertical distance (c) between the parallel coupling element (8) and reference element
(9) ermittelt wird. (9) is determined.
10. Verfahren nach Anspruch 9, 10. The method according to claim 9,
dadurch gekennzeichnet,  characterized,
dass mit einer Abstandsmessvorrichtung der Abstand zwischen Resonator und Referenzelement gemessen wird.  in that the distance between the resonator and the reference element is measured with a distance measuring device.
1 1 . Verfahren nach Anspruch 10, 1 1. Method according to claim 10,
dadurch gekennzeichnet,  characterized,
dass der Abstand (a, b) zwischen der Materialbahn (6) und den Elementen (8, 9) mittels einer Regelung, während der Messung der bewegten Materialbahn, geregelt wird und das Flächengewicht durch die Beeinflussung der Resonanzkurve in Bezug auf den mit der Abstandsmessvorrichtung gemessenen Abstand (c) zwischen Einkoppelelement (8) und Referenzelement (9) ermittelt wird.  in that the distance (a, b) between the material web (6) and the elements (8, 9) is regulated by means of a control during the measurement of the moving material web and the basis weight is controlled by influencing the resonance curve with respect to that with the distance measuring device measured distance (c) between the coupling element (8) and reference element (9) is determined.
12. Verfahren nach Anspruch 1 1 , 12. The method according to claim 1 1,
dadurch gekennzeichnet,  characterized,
dass der Abstand (a, b) zwischen Resonator (8) und Bahnmaterial (6) sowie zwischen Referenzelement (9) und Bahnmaterial (6) auf 1 pm bis 10000 pm geregelt wird.  the distance (a, b) between the resonator (8) and the web material (6) and between the reference element (9) and the web material (6) is regulated to 1 pm to 10000 pm.
13. Verfahren nach einem der Ansprüche 9 bis 12, 13. The method according to any one of claims 9 to 12,
dadurch gekennzeichnet, dass mindestens ein Mikrowellensensorelement, das Einkoppelelement (8) und/oder das Referenzelement (9), mittels eines, durch Druckluft erzeugten, ersten einstellbaren oder geregelten Luftkissens (4) in Richtung Materialbahn bewegt wird und mittels eines zweiten einstellbaren oder geregelten Luftkissens (5) gegenüber der Materialbahn (6) auf Abstand gehalten wird. characterized, in that at least one microwave sensor element, the coupling element (8) and / or the reference element (9) is moved in the direction of the material web by means of a first adjustable or regulated air cushion (4) generated by compressed air and by means of a second adjustable or regulated air cushion (5). opposite to the material web (6) is kept at a distance.
Verfahren nach einem der Ansprüche 9 bis 13, Method according to one of claims 9 to 13,
dadurch gekennzeichnet,  characterized,
dass zur Messung des Flächengewichtes ein betreffender Mikrowellenresonator (8) in einem Frequenzbereich von größer 20 GHz betrieben wird. for measuring the basis weight, a relevant microwave resonator (8) is operated in a frequency range of greater than 20 GHz.
EP11790974.7A 2010-12-16 2011-12-05 Determination of weight per unit area of a material web using a microwave sensor, the distances between the material web and the surfaces of the microwave sensor being adjusted to a constant value by means of air cushions Withdrawn EP2652198A1 (en)

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US20130277122A1 (en) 2013-10-24
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CN103370472A (en) 2013-10-23
US9279713B2 (en) 2016-03-08

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