EP0790006A2 - Method and apparatus for determining the density of a rod in the tobacco industry - Google Patents

Method and apparatus for determining the density of a rod in the tobacco industry Download PDF

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Publication number
EP0790006A2
EP0790006A2 EP97101524A EP97101524A EP0790006A2 EP 0790006 A2 EP0790006 A2 EP 0790006A2 EP 97101524 A EP97101524 A EP 97101524A EP 97101524 A EP97101524 A EP 97101524A EP 0790006 A2 EP0790006 A2 EP 0790006A2
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EP
European Patent Office
Prior art keywords
strand
density
signal
measurement signals
ray
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Granted
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EP97101524A
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German (de)
French (fr)
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EP0790006B1 (en
EP0790006A3 (en
Inventor
Reinhard Hoppe
Henning Dr. Möller
Andreas Noack
Matthias Overath
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Koerber Technologies GmbH
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Hauni Maschinenbau GmbH
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    • A—HUMAN NECESSITIES
    • A24—TOBACCO; CIGARS; CIGARETTES; SIMULATED SMOKING DEVICES; SMOKERS' REQUISITES
    • A24C—MACHINES FOR MAKING CIGARS OR CIGARETTES
    • A24C5/00—Making cigarettes; Making tipping materials for, or attaching filters or mouthpieces to, cigars or cigarettes
    • A24C5/32—Separating, ordering, counting or examining cigarettes; Regulating the feeding of tobacco according to rod or cigarette condition
    • A24C5/34—Examining cigarettes or the rod, e.g. for regulating the feeding of tobacco; Removing defective cigarettes
    • A24C5/3412—Examining cigarettes or the rod, e.g. for regulating the feeding of tobacco; Removing defective cigarettes by means of light, radiation or electrostatic fields

Definitions

  • the invention relates to a method according to the preamble of claim 1 and a device according to the preamble of claim 6.
  • Density measuring devices are used in rod machines in the tobacco processing industry in order to monitor the quantity of material and the uniformity of the material distribution in the rod and to ensure as far as possible in accordance with certain specifications. This applies to the tobacco content in a tobacco rod for the production of smokable tobacco items such as cigarettes, pillars, cigar ribs etc. as well as to the content of filter material in a filter rod.
  • the uniform filling of the strand is known to be an important quality criterion for the articles made from the strand. Its density is recorded as a measure of the filling of the strand, that is to say the amount of tobacco or filter material in the strand.
  • Density measuring devices which penetrate the strand with radioactive radiation - as a rule with the beta radiation of a strontium 90 preparation (US Pat. No. 4,424,443) - are currently known and generally used, the decrease in their intensity when penetrating the strand as a measure of the density of the strand is detected.
  • the measurement results obtained with this measuring device are characterized by a high level of reliability, but because of the permanent beta emitter required, they are purchased with complex safety measures on the machine.
  • a density measuring device which uses infrared light as measuring radiation has also become known more recently (US Pat. No. 4,805,641).
  • the advantage of this device is that it does not require a radioactive radiation source, but it still does not quite achieve the reliability of nuclear density measurement.
  • US Pat. No. 3,056,026 shows such a measuring device, the basically works like a density measuring head with a nuclear radiation source.
  • the X-ray radiation penetrating the strand is detected with an ionization chamber, which makes the measurement slow and its resolution in the longitudinal direction of the strand low.
  • US Pat. No. 4,785,830 describes a measuring device on a cigarette rod machine in which an uncovered tobacco rod in the tobacco channel is X-rayed. The radiation penetrating the strand is detected with a sensor array in order to separately determine the density of the fiber material in different strand height sections before the cigarette rod is finished and thus to recognize the density distribution in the rod and the strand structures. This should allow a targeted intervention in the strand production for the purpose of optimizing the strand structure. This measurement should also be able to be carried out on the wrapped tobacco rod (cigarette rod), but the document does not contain any further details.
  • 4,865,052 also shows a device for measuring the density of an uncovered tobacco rod which is conveyed in the tobacco duct of a rod machine by means of X-ray radiation penetrating the rod. The radiation is detected with a sensor array. From the bottom of the tobacco channel, the measured values of the sensors are added up until the sum reaches a predetermined target value, and the downstream excess removal device is adjusted accordingly, so that the weight or density of the strand is pre-set here. This procedure does not make sense for measurements on the cigarette rod.
  • the invention has for its object to provide a further method and another device of the type described above.
  • the invention offers the advantage of a very fast and accurate density measurement of high resolution. This ensures that the drift phenomena of the detectors or changes in the intensity of the radiation source cannot affect the measurement results.
  • the invention therefore offers a very reliable strand density measurement.
  • the safety-related difficulties that a nuclear beta radiation source causes do not occur here.
  • the security effort is low.
  • the dimensions of the X-ray measuring head according to the invention can be adapted to that of a nuclear measuring head, so that it can be exchanged for the X-ray measuring head in existing machines.
  • Figure 1 shows a schematic diagram of a device for determining the density of a fiber strand of the tobacco processing industry according to the invention.
  • 1 with a continuously moving cigarette rod is designated, which has a wrapping 2 of cigarette paper and a filling 3 of tobacco fibers.
  • the strand can also be a filter strand of the tobacco processing industry or a strand for the production of cigarillos, cigars, pillars, etc.
  • the strand is conveyed in the longitudinal direction, that is to say approximately perpendicular to the plane of the drawing in FIG. 1, along a conveying path of a cigarette rod making machine (not shown in the drawing, for example of the Protos 100 type of the applicant) and passes through a tube 6 which is transparent to X-rays in a measuring station 4.
  • This tube can consist, for example, of a thin aluminum or titanium sheet.
  • a polycarbonate (PC), for example MACROLON from BAYER AG or a polyethylene ether ketone (PEEK) with a wall thickness of approximately 0.2 mm is preferably used as the material for the tube.
  • the illustration in the drawing is not to scale, so that here the wall thickness of the tube 6 appears too large.
  • An x-ray radiation source 7 emits an x-ray radiation 8, which is idealized in FIG. 1. In fact, the radiation does not emanate in parallel from the X-ray source.
  • the limitation of the x-ray radiation 8 by means of diaphragms 9 and 9a has the effect that through the gaps 11 and 11a formed by the diaphragms a radiation component penetrates the strand, the radiation pattern of which approximates a parallel radiation pattern at least to an extent sufficient for the measurement purpose.
  • An X-ray source for example, is an industrial X-ray machine of the MF1-30-2 type with a normal focus X-ray tube FK 60-10 W from Rich. Seifert & Co., D-22926 Ahrensburg, in question.
  • the measurement of the intensity of the X-radiation is carried out by means of an X-ray receiver 12, which is attached behind the gap 11a.
  • This X-ray receiver 12 is a line array 13 with a plurality of X-ray detectors 14.1 to 14.n. formed, which are arranged in a row one behind the other in the array 13.
  • n is the total number of X-ray detectors 14 provided in the array 13.
  • n 11.
  • i is a serial number between 1 and n.
  • the x-ray-sensitive area of the x-ray detectors is, for example, 1 mm in height, that is to say transversely to the direction of the strand, and 4 mm in width, that is to say in the direction of the strand.
  • the gaps 11 and 11a are approximately as wide as the detectors 14.
  • the X-ray detectors 14.1 to 14.n are all connected separately to an evaluation arrangement 16, which processes the measurement signals emitted by the X-ray detectors into a density signal 17, which is emitted to a control arrangement 18 of a device for influencing the strand density.
  • a device in a cigarette rod machine is, for example, a device for removing excess from the tobacco rod, with which the amount of tobacco entering the cigarette rod is adjusted. Such devices are known and need no further description here.
  • the detector array 13 comprises at least one additional X-ray detector 14.2 which detects a part of the X-rays which does not penetrate the strand. Its measurement signal S 2 is processed as a reference signal in the evaluation arrangement 16.
  • the detector array 13 also has at least one further X-ray detector 14.1, which is permanently shielded from the radiation from the X-ray source 7. This further detector 14.1 permanently emits a signal S 1 corresponding to its dark current, which is used in the evaluation arrangement 16 to compensate for drift phenomena in the detectors. Only one additional x-ray detector and another x-ray detector are shown in the drawing. The measurement can be further improved and made more reliable if more detectors each receive the undamped X-rays or generate a signal corresponding to their dark current.
  • the measuring device is first calibrated.
  • the X-ray radiation source 7 is switched off or dimmed toward the radiation receiver 12 by means of a shutter (not shown).
  • the measurement signals S 1 to S n of the X-ray detectors 14.1 to 14.n now represent their dark currents.
  • the measurement signals S 1 to S n obtained when the X-ray source is switched off or the X-ray receivers are dimmed are also referred to as dark signals.
  • the dark signals of the x-ray detectors 14.2 to 14.n are processed with the dark signal of the x-ray detector 14.1, which is also referred to as S D for better identification, to compensate values j D, 2 to j D, n which are suitable for later use in density measurement in Storage sections 19.2 to 19.n of the evaluation arrangement 16 are stored as constants. Then, with the X-ray source 7 switched on, the current of the X-ray detectors is measured at full intensity of the radiation without strand.
  • the resulting measurement signals S 2 to S n of the X-ray radiation detectors 14.2 to 14.n represent reference measurement values.
  • the reference measurement values S 3 to S n are identified with the reference measurement value S 2 of the additional X-ray radiation detector 14.2, which is also referred to as S 0 for better identification as a reference measurement value is processed into reference values j 0.3 to j 0, n , which are stored as constants in memory sections 21.3 to 21.n of the evaluation arrangement 16.
  • a strand 1 is moved through the tube 6 in the measuring station 12, which attenuates the radiation striking the X-ray radiation detectors in accordance with its density.
  • the intensity of the radiation weakened in accordance with the density is detected with the X-ray radiation detectors 14.3 to 14.n, which emit the corresponding measurement signals S 3 to S n to the evaluation arrangement 16.
  • the evaluation arrangement compares these measurement signals in the function blocks 22.3 to 22.n with the stored compensation values j D, 3 to j D, n corresponding to the dark currents of the X-ray detectors 14.3 to 14.n.
  • the compensation values in turn are calculated in calculation levels 24.3 to 24.n corrected as a function of the respectively current dark signal S D of the X-ray detector 14.1 which is permanently shielded from the X-radiation, whereby compensation for drift phenomena occurring in the detectors is effected.
  • the effect of the aging processes of the detectors or of heat changes in their characteristics is thus reliably eliminated.
  • the comparators 22.3 to 22.n give corrected measurement signals S 3, k to S n, k to the downstream calculation stages 23.3 to 23, n, which represent the X-rays which hit the detectors 14.3 to 14.n after passing through the strand, ie correspond to the strand density in the strand height position detected by the respective detector.
  • reference signals I 3, k to I n, k are transferred to the calculation stages 23.3 to 23.n. These reference signals result from the reference values j 0.3 to j 0, n stored in the memory sections 21.3 to 21.n, which are stored in correction stages 25.3 to 25.n as a function of the current reference measurement signal S 2 or S 0 full X-ray illuminated X-ray detector 14.2 are corrected.
  • a correction signal S 2, k is formed by comparison with the reference value j D, 2 of the detector 14.2 in the comparator stage 22.2, which is corrected in the compensation section 24.2 as a function of the dark signal S D of the permanently shielded radiation receiver 14.1 and is stored in the memory section 19.2 as a constant, which is used in correction stages 25.3 to 25.n to correct the reference values j 0.3 to j 0, n .
  • the additional detector 14.2 which continuously receives the undamped intensity of the X-ray radiation source 7 and whose measurement signal S 2 represents a permanent current reference signal S 0
  • the further detector 14.1 which is permanently shielded from the X-ray radiation source 7 and always on Outputs dark current signal S D as a compensation signal, achieved that the density measurement is independent of fluctuations in intensity of the X-ray source 7, temperature drifts and signs of aging of the detectors.
  • the corrected measurement signals S 3, k to S n, k become separate density signals in the calculation stages 23.3 to 23.n or with the corrected reference signals I 3, k to I n, k Processed D 3 to D n , each representing the density in an associated strand height position. This is done by logarithmizing the ratio (quotient) of the reference signal and the corrected measurement signal.
  • the resulting separate density signals D 3 to D n are added in an addition stage 26 and output as a density signal 17 to the connected control arrangement 18. If necessary, the mean value of the separate density signals D 3 to D n can also be formed as a density signal representing the strand density.
  • the logarithmization of the individual measured values in the calculation stages 23 has the advantage over the logarithmization of the integrated density value that is common today that a mathematically correct and thus a more reliable and more accurate statement about the strand density in the strand section currently being illuminated results.
  • Another possibility provided according to the invention is to first multiply the quotients of the reference signals and the associated corrected measurement signals and logarithmize the product thus formed in order to obtain the desired density signal.
  • the extent of the radiation-sensitive area of the X-ray radiation detectors is preferably very small.
  • detectors are currently preferred whose radiation-sensitive area is approximately 4 mm in the longitudinal direction of the strand and approximately 1 mm transversely to the strand.
  • the individual detectors thus detect strand sections of very little extent, in which the density can be assumed to be at least approximately homogeneous. This also contributes significantly to the accuracy of the measurement results because the logarithmization of the individual intensity values is a mathematically correct evaluation step, so that falsification of results is prevented.
  • this design of the detectors leads to a high resolution.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Manufacturing Of Cigar And Cigarette Tobacco (AREA)
  • Cigarettes, Filters, And Manufacturing Of Filters (AREA)

Abstract

The method involves detecting the intensity of X-rays (8) passing though a cigarette chord (6) and processing (16) the resulting intensity signal into a signal representing the density of the chord. The intensity of the X-rays is separately detected at a number of different heights on the chord. Measurement signals (S1 - Sn) representing the detected intensities are processed to form a single density signal (17). At each chord height position the intensity of a part of the X-rays passing though a section with negligible density inhomogeneity is detected.

Description

Die Erfindung betrifft ein Verfahren nach dem Oberbegriff des Anspruchs 1 und eine Vorrichtung nach dem Oberbegriff des Anspruchs 6.The invention relates to a method according to the preamble of claim 1 and a device according to the preamble of claim 6.

In Strangmaschinen der tabakverarbeitenden Industrie werden Dichtemeßeinrichtungen eingesetzt, um die Materialmenge und die Gleichmäßigkeit der Materialverteilung im Strang zu überwachen und möglichst weitgehend entsprechend bestimmten Vorgaben sicherzustellen. Das gilt für den Tabakgehalt in einem Tabakstrang für die Herstellung von rauchbaren Tabakartikeln wie Zigaretten, Stumpen, Zigarrillos usw. wie auch für den Gehalt an Filtermaterial in einem Filterstrang. Die gleichmäßige Füllung des Strangs ist bekanntlich ein wichtiges Qualitätskriterium für die aus dem Strang hergestellten Artikel. Als Maß für die Füllung des Strangs, also für die Tabak- oder Filtermaterialmenge im Strang, wird seine Dichte erfaßt.Density measuring devices are used in rod machines in the tobacco processing industry in order to monitor the quantity of material and the uniformity of the material distribution in the rod and to ensure as far as possible in accordance with certain specifications. This applies to the tobacco content in a tobacco rod for the production of smokable tobacco items such as cigarettes, pillars, cigar ribs etc. as well as to the content of filter material in a filter rod. The uniform filling of the strand is known to be an important quality criterion for the articles made from the strand. Its density is recorded as a measure of the filling of the strand, that is to say the amount of tobacco or filter material in the strand.

Bekannt und allgemein gebräuchlich sind derzeit Dichtemeßeinrichtungen, die mit radioaktiver Strahlung - in der Regel mit der Betastrahlung eines Strontium 90-Präparates (US-PS 4 424 443) - den Strang durchdringen, deren Intensitätsabfall beim Durchdringen des Strangs als Maß für die Dichte des Strangs erfaßt wird. Die mit dieser Meßeinrichtung gewonnenen Meßergebnisse zeichnen sich durch hohe Zuverlässigkeit aus, werden aber wegen des erforderlichen permanenten Beta-Strahlers mit aufwendigen Sicherheitsmaßnahmen an der Maschine erkauft.Density measuring devices which penetrate the strand with radioactive radiation - as a rule with the beta radiation of a strontium 90 preparation (US Pat. No. 4,424,443) - are currently known and generally used, the decrease in their intensity when penetrating the strand as a measure of the density of the strand is detected. The measurement results obtained with this measuring device are characterized by a high level of reliability, but because of the permanent beta emitter required, they are purchased with complex safety measures on the machine.

Es ist in jüngerer Zeit auch eine Dichtemeßeinrichtung bekanntgeworden, die mit infrarotem Licht als Meßstrahlung arbeitet (US-PS 4 805 641). Diese Einrichtung hat den Vorteil, daß sie ohne eine radioaktive Strahlungsquelle auskommt, erreicht aber noch nicht ganz die Zuverlässigkeit der nuklearen Dichtemessung.A density measuring device which uses infrared light as measuring radiation has also become known more recently (US Pat. No. 4,805,641). The advantage of this device is that it does not require a radioactive radiation source, but it still does not quite achieve the reliability of nuclear density measurement.

Auch die Verwendung von Röntgenstrahlung als Meßstrahlung für die Dichtemessung ist bereits vorgeschlagen worden. Die US-PS 3 056 026 zeigt eine solche Meßeinrichtung, die im Prinzip wie ein Dichtemeßkopf mit nuklearer Strahlungsquelle arbeitet. Die den Strang durchdringende Röntgenstrahlung wird mit einer Ionisationskammer erfaßt, was die Messung langsam und ihre Auflösung in Längsrichtung des Strangs gering macht.The use of X-rays as measuring radiation for density measurement has also been proposed. US Pat. No. 3,056,026 shows such a measuring device, the basically works like a density measuring head with a nuclear radiation source. The X-ray radiation penetrating the strand is detected with an ionization chamber, which makes the measurement slow and its resolution in the longitudinal direction of the strand low.

In der US-PS 4 785 830 ist eine Meßeinrichtung an einer Zigarettenstrangmaschine beschrieben, in der ein nicht umhüllter Tabakstrang im Tabakkanal mit Röntgenstrahlung durchleuchtet wird. Die den Strang durchdringende Strahlung wird mit einem Sensorarray erfaßt, um vor der Fertigstellung des Zigarettenstrangs die Dichte des Fasermaterials in verschiedenen Stranghöhenabschnitten separat zu ermitteln und so die Dichteverteilung im Strang und die Strangstrukturen zu erkennen. Das soll einen gezielten Eingriff in die Strangherstellung zum Zweck der Optimierung des Strangaufbaus erlauben. Diese Messung soll auch am umhüllten Tabakstrang (Zigarettenstrang) vorgenommen werden können, wozu die Schrift aber keine näheren Angaben erhält. Die US-PS 4 865 052 zeigt ebenfalls eine Einrichtung zum Messen der Dichte eines nicht umhüllten Tabakstrangs, der im Tabakkanal einer Strangmaschine gefördert wird, mittels den Strang durchdringender Röntgenstrahlung. Die Strahlung wird mit einem Sensorarray erfaßt. Vom Grund des Tabakkanals her werden die Meßwerte der Sensoren aufsummiert bis die Summe einen vorgegebenen Sollwert erreicht, und entsprechend wird die stromab angeordnete Überschußabnahmeeinrichtung eingestellt, so daß hier eine Vorauseinstellung des Gewichts bzw. der Dichte des Strangs erfolgt. Für Messungen am Zigarettenstrang ist dieses Vorgehen nicht sinnvoll.US Pat. No. 4,785,830 describes a measuring device on a cigarette rod machine in which an uncovered tobacco rod in the tobacco channel is X-rayed. The radiation penetrating the strand is detected with a sensor array in order to separately determine the density of the fiber material in different strand height sections before the cigarette rod is finished and thus to recognize the density distribution in the rod and the strand structures. This should allow a targeted intervention in the strand production for the purpose of optimizing the strand structure. This measurement should also be able to be carried out on the wrapped tobacco rod (cigarette rod), but the document does not contain any further details. US Pat. No. 4,865,052 also shows a device for measuring the density of an uncovered tobacco rod which is conveyed in the tobacco duct of a rod machine by means of X-ray radiation penetrating the rod. The radiation is detected with a sensor array. From the bottom of the tobacco channel, the measured values of the sensors are added up until the sum reaches a predetermined target value, and the downstream excess removal device is adjusted accordingly, so that the weight or density of the strand is pre-set here. This procedure does not make sense for measurements on the cigarette rod.

Die im Stand der Technik bekannten Dichtemessungen mit Röntgenstrahlung haben sich in der Praxis nicht bewährt und konnten sich in der industriellen Zigarettenfertigung nicht durchsetzen. Es besteht daher weiterhin der Wunsch und das Bedürfnis, eine Meßtechnik in die Hand zu bekommen, die zuverlässig die Strangdichte erfaßt, genau und hoch auflösend arbeitet und mit geringem Aufwand insbesondere auch in sicherheitstechnischer Hinsicht gehandhabt und eingesetzt werden kann.The X-ray density measurements known in the prior art have not proven themselves in practice and have not been able to establish themselves in industrial cigarette manufacture. There is therefore still the desire and the need to get a measuring technique in hand that reliably detects the strand density, works precisely and with high resolution, and can be handled and used with little effort, particularly in terms of safety.

Der Erfindung liegt die Aufgabe zugrunde, ein weiteres Verfahren und eine weitere Vorrichtung der eingangs beschriebenen Art anzugeben.The invention has for its object to provide a further method and another device of the type described above.

Gelöst wird diese Aufgabe bei einem Verfahren der eingangs angegebenen Art erfindungsgemäß durch die Maßnahmen, die im Kennzeichen des Anspruchs 1, und bei einer Vorrichtung der eingangs angegebenen Art mit den Merkmalen, die im Kennzeichen des Anspruchs 6 angegeben sind. Fortsetzungen, Weiterbildungen und vorteilhafte Ausgestaltungen des Verfahrens und der Vorrichtung nach der Erfindung sind in den Unteransprüchen angegeben.This object is achieved according to the invention in a method of the type specified at the outset by the measures specified in the characterizing part of claim 1, and in a device of the type specified initially with the features specified in the characterizing part of claim 6. Continuations, developments and advantageous refinements of the method and the device according to the invention are specified in the subclaims.

Die Erfindung bietet den Vorteil einer sehr schnellen und genauen Dichtemessung hoher Auflösung. Dabei ist gewährleistet, daß sich die Drifterscheinungen der Detektoren oder Intensitätsveränderungen der Strahlungsquelle nicht auf die Meßergebnisse auswirken können. Die Erfindung bietet also eine sehr zuverlässige Strangdichtemessung. Die sicherheitstechnischen Schwierigkeiten, die eine nukleare Betastrahlungsquelle verursacht, treten hier nicht auf. Der sicherheitstechnische Aufwand ist gering. Die Abmessungen des Röntgenmeßkopfes gemäß der Erfindung können an die eines nuklearen Meßkopfes angepaßt werden, so daß dieser in vorhandenen Maschinen gegen den Röntgenmeßkopf ausgetauscht werden kann.The invention offers the advantage of a very fast and accurate density measurement of high resolution. This ensures that the drift phenomena of the detectors or changes in the intensity of the radiation source cannot affect the measurement results. The invention therefore offers a very reliable strand density measurement. The safety-related difficulties that a nuclear beta radiation source causes do not occur here. The security effort is low. The dimensions of the X-ray measuring head according to the invention can be adapted to that of a nuclear measuring head, so that it can be exchanged for the X-ray measuring head in existing machines.

Die Erfindung wird nun anhand der Zeichnung näher erläutert.The invention will now be explained in more detail with reference to the drawing.

Es zeigen

Figur 1
eine Prinzipdarstellung einer Meßvorrichtung nach der Erfindung und
Figur 2
eine Blockdarstellung der Meßwertauswertung.
Show it
Figure 1
a schematic diagram of a measuring device according to the invention and
Figure 2
a block diagram of the measured value evaluation.

Figur 1 zeigt eine Prinzipdarstellung einer Vorrichtung zur Bestimmung der Dichte eines Faserstrangs der tabakverarbeitenden Industrie gemäß der Erfindung. Mit 1 ist ein kontinuierlich bewegter Zigarettenstrang bezeichnet, der eine Umhüllung 2 aus Zigarettenpapier und eine Füllung 3 aus Tabakfasern aufweist. Bei dem Strang kann es sich auch um einen Filterstrang der tabakverarbeitenden Industrie oder um einen Strang für die Herstellung von Zigarrillos, Zigarren, Stumpen usw. handeln.Figure 1 shows a schematic diagram of a device for determining the density of a fiber strand of the tobacco processing industry according to the invention. 1 with a continuously moving cigarette rod is designated, which has a wrapping 2 of cigarette paper and a filling 3 of tobacco fibers. The strand can also be a filter strand of the tobacco processing industry or a strand for the production of cigarillos, cigars, pillars, etc.

Der Strang wird in Längsrichtung, also etwa senkrecht zur Zeichenebene der Figur 1, entlang einer Förderstrecke einer in der Zeichnung nicht weiter dargestellten Zigarettenstrangmaschine, beispielsweise vom Typ Protos 100 der Anmelderin, gefördert und durchläuft dabei in einer Meßstation 4 einen für Röntgenstrahlung durchlässigen Tubus 6. Dieser Tubus kann beispielsweise aus einem dünnen Aluminium- oder Titanblech bestehen. Vorzugsweise wird als Material für den Tubus aber ein Polycarbonat (PC), beispielsweise MACROLON der BAYER AG oder ein Polyethylenetherketon (PEEK) mit einer Wanddicke von etwa 0,2 mm eingesetzt. Die Darstellung in der Zeichnung ist nicht maßstabsgerecht, so daß hier die Wanddicke des Tubus 6 zu groß erscheint.The strand is conveyed in the longitudinal direction, that is to say approximately perpendicular to the plane of the drawing in FIG. 1, along a conveying path of a cigarette rod making machine (not shown in the drawing, for example of the Protos 100 type of the applicant) and passes through a tube 6 which is transparent to X-rays in a measuring station 4. This tube can consist, for example, of a thin aluminum or titanium sheet. However, a polycarbonate (PC), for example MACROLON from BAYER AG or a polyethylene ether ketone (PEEK) with a wall thickness of approximately 0.2 mm, is preferably used as the material for the tube. The illustration in the drawing is not to scale, so that here the wall thickness of the tube 6 appears too large.

Eine Röntgenstrahlungsquelle 7 sendet eine Röntgenstrahlung 8 aus, die in der Figur 1 idealisiert dargestellt ist. Tatsächlich geht die Strahlung nicht parallel von der Röntgenstrahlungsquelle aus. Die Begrenzung der Röntgenstrahlung 8 durch Blenden 9 und 9a bewirkt aber, daß durch die von den Blenden gebildeten Spalte 11 und 11a ein Strahlungsanteil den Strang durchdringt, dessen Strahlungsverlauf einem parallelen Strahlungsverlauf wenigstens in einem für den Meßzweck ausreichenden Maße angenähert ist. Als Röntgenstrahlungsquelle kommt beispielsweise ein Industrie-Röntgengerät des Typs MF1-30-2 mit einer Normal-Fokus-Röntgenröhre FK 60-10 W der Fa. Rich. Seifert & Co., D-22926 Ahrensburg, in Frage.An x-ray radiation source 7 emits an x-ray radiation 8, which is idealized in FIG. 1. In fact, the radiation does not emanate in parallel from the X-ray source. The limitation of the x-ray radiation 8 by means of diaphragms 9 and 9a, however, has the effect that through the gaps 11 and 11a formed by the diaphragms a radiation component penetrates the strand, the radiation pattern of which approximates a parallel radiation pattern at least to an extent sufficient for the measurement purpose. An X-ray source, for example, is an industrial X-ray machine of the MF1-30-2 type with a normal focus X-ray tube FK 60-10 W from Rich. Seifert & Co., D-22926 Ahrensburg, in question.

Die Messung der Intensität der Röntgenstrahlung erfolgt mittels eines Röntgenstrahlungsempfängers 12, der hinter dem Spalt 11a angebracht ist. Dieser Röntgenstrahlungsempfänger 12 ist als Linienarray 13 mit einer Vielzahl von Röntgendetektoren 14.1 bis 14.n ausgebildet, die in einer Reihe hintereinander in dem Array 13 angeordnet sind. n ist die Gesamtzahl der in dem Array 13 vorgesehenen Röntgendetektoren 14. In dem in der Figur 1 dargestellten Ausführungsbeispiel beträgt n = 11. Bevorzugt wird eine Ausführung mit 16 derartigen Röntgendetektoren im Array 13, z.B. vom Typ CXM-HS 03-16K der Firma CRYSTAL.
i ist eine laufende Nummer zwischen 1 und n. Die röntgenempfindliche Fläche der Röntgendetektoren beträgt beispielsweise 1 mm in der Höhe, also quer zur Strangrichtung und 4 mm in der Breite, also in Strangrichtung. Die Spalte 11 und 11a sind etwa so breit wie die Detektoren 14.The measurement of the intensity of the X-radiation is carried out by means of an X-ray receiver 12, which is attached behind the gap 11a. This X-ray receiver 12 is a line array 13 with a plurality of X-ray detectors 14.1 to 14.n. formed, which are arranged in a row one behind the other in the array 13. n is the total number of X-ray detectors 14 provided in the array 13. In the exemplary embodiment shown in FIG. 1, n = 11. An embodiment with 16 such X-ray detectors in the array 13, for example of the type CXM-HS 03-16K from CRYSTAL, is preferred .
i is a serial number between 1 and n. The x-ray-sensitive area of the x-ray detectors is, for example, 1 mm in height, that is to say transversely to the direction of the strand, and 4 mm in width, that is to say in the direction of the strand. The gaps 11 and 11a are approximately as wide as the detectors 14.

Die Röntgendetektoren 14.1 bis 14.n sind alle separat an eine Auswertanordnung 16 angeschlossen, welche die von den Röntgendetektoren abgegebenen Meßsignale zu einem Dichtesignal 17 verarbeitet, das an eine Steueranordnung 18 eines Gerätes zur Beeinflussung der Strangdichte abgegeben wird. Ein derartiges Gerät ist in einer Zigarettenstrangmaschine beispielsweise eine Einrichtung zum Abnehmen von Überschuß vom Tabakstrang, mit dem die Menge des in den Zigarettenstrang gelangenden Tabaks eingestellt wird. Derartige Geräte sind bekannt und bedürfen hier keiner näheren Beschreibung.The X-ray detectors 14.1 to 14.n are all connected separately to an evaluation arrangement 16, which processes the measurement signals emitted by the X-ray detectors into a density signal 17, which is emitted to a control arrangement 18 of a device for influencing the strand density. Such a device in a cigarette rod machine is, for example, a device for removing excess from the tobacco rod, with which the amount of tobacco entering the cigarette rod is adjusted. Such devices are known and need no further description here.

Das Detektorarray 13 umfaßt außer den die Intensität der den Strang selbst durchdringenden Röntgenstrahlung erfassenden Detektoren wenigstens einen zusätzlichen Röntgenstrahlendetektor 14.2, der einen den Strang nicht durchdringenden Teil der Röntgenstrahlung erfaßt. Sein Meßsignal S2 wird als Referenzsignal in der Auswertanordnung 16 verarbeitet. Das Detektorarray 13 weist darüber hinaus wenigstens noch einen weiteren Röntgenstrahlendetektor 14.1 auf, der permanent gegen die Strahlung der Röntgenstrahlenquelle 7 abgeschirmt ist. Dieser weitere Detektor 14.1 gibt permanent ein seinem Dunkelstrom entsprechendes Signal S1 ab, das in der Auswertanordnung 16 zur Kompensation von Drifterscheinungen in den Detektoren genutzt wird. In der Zeichnung sind lediglich ein zusätzlicher Röntgenstrahlungsdetektor und ein weiterer Röntgenstrahlungsdetektordargestellt. Die Messung kann weiter verbessert und zuverlässiger gemacht werden, wenn jeweils merere Detektoren die ungedämpfte Röntgenstrahlung empfangen bzw. ein ihrem Dunkelstrom entsprechendes Signal erzeugen.In addition to the detectors which detect the intensity of the X-rays penetrating the strand itself, the detector array 13 comprises at least one additional X-ray detector 14.2 which detects a part of the X-rays which does not penetrate the strand. Its measurement signal S 2 is processed as a reference signal in the evaluation arrangement 16. The detector array 13 also has at least one further X-ray detector 14.1, which is permanently shielded from the radiation from the X-ray source 7. This further detector 14.1 permanently emits a signal S 1 corresponding to its dark current, which is used in the evaluation arrangement 16 to compensate for drift phenomena in the detectors. Only one additional x-ray detector and another x-ray detector are shown in the drawing. The measurement can be further improved and made more reliable if more detectors each receive the undamped X-rays or generate a signal corresponding to their dark current.

Die Arbeitsweise der Auswertanordnung 16 bei der Verarbeitung der von den Detektoren 14.1 bis 14.n abgegebenen Meßsignale S1 bis Sn wird anhand des in Figur 2 dargestellten Funktionsdiagramms erläutert.The mode of operation of the evaluation arrangement 16 in the processing of the measurement signals S 1 to S n emitted by the detectors 14.1 to 14.n is explained using the function diagram shown in FIG.

Zur Vorbereitung der Strangdichtemessung wird die Meßvorrichtung zunächst kalibriert. Dazu wird die Röntgenstrahlungsquelle 7 abgeschaltet oder mittels eines nicht dargestellten Shutters zum Strahlungsempfänger 12 hin abgeblendet. Die Meßsignale S1 bis Sn der Röntgenstrahlungsdetektoren 14.1 bis 14.n repräsentieren jetzt deren Dunkelströme. Die bei abgeschalteter Röntgenstrahlungsquelle oder abgeblendeten Röntgenstrahlungsempfängern gewonnenen Meßsignale S1 bis Sn werden auch als Dunkelsignale bezeichnet. Die Dunkelsignale der Röntgenstrahlendetektoren 14.2 bis 14.n werden mit dem Dunkelsignal des Röntgenstrahlendetektors 14.1, das zur besseren Kenntlichmachung auch mit SD bezeichnet wird, zu Kompensationswerten jD,2 bis jD,n verarbeitet, die für die spätere Verwendung bei der Dichtemessung in Speichersektionen 19.2 bis 19.n der Auswertanordnung 16 als Konstanten abgelegt werden. Anschließend wird mit eingeschalteter Röntgenstrahlungsquelle 7 der Strom der Röntgenstrahlungsdetektoren bei voller Intensität der Strahlung ohne Strang gemessen. Die sich dabei ergebenden Meßsignale S2 bis Sn der Röntgenstrahlungsdetektoren 14.2 bis 14.n stellen Referenzmeßwerte dar. Die Referenzmeßwerte S3 bis Sn werden mit dem Referenzmeßwert S2 des zusätzlichen Röntgenstrahlungsdetektors 14.2, das zur besseren Kenntlichmachung als Referenzmeßwert auch mit S0 bezeichnet wird, zu Referenzwerten j0,3 bis j0,n verarbeitet, die in Speichersektionen 21.3 bis 21.n der Auswertanordnung 16 als Konstanten hinterlegt werden.To prepare the strand density measurement, the measuring device is first calibrated. For this purpose, the X-ray radiation source 7 is switched off or dimmed toward the radiation receiver 12 by means of a shutter (not shown). The measurement signals S 1 to S n of the X-ray detectors 14.1 to 14.n now represent their dark currents. The measurement signals S 1 to S n obtained when the X-ray source is switched off or the X-ray receivers are dimmed are also referred to as dark signals. The dark signals of the x-ray detectors 14.2 to 14.n are processed with the dark signal of the x-ray detector 14.1, which is also referred to as S D for better identification, to compensate values j D, 2 to j D, n which are suitable for later use in density measurement in Storage sections 19.2 to 19.n of the evaluation arrangement 16 are stored as constants. Then, with the X-ray source 7 switched on, the current of the X-ray detectors is measured at full intensity of the radiation without strand. The resulting measurement signals S 2 to S n of the X-ray radiation detectors 14.2 to 14.n represent reference measurement values. The reference measurement values S 3 to S n are identified with the reference measurement value S 2 of the additional X-ray radiation detector 14.2, which is also referred to as S 0 for better identification as a reference measurement value is processed into reference values j 0.3 to j 0, n , which are stored as constants in memory sections 21.3 to 21.n of the evaluation arrangement 16.

Zur Dichtemessung wird ein Strang 1 durch den Tubus 6 in der Meßstation 12 bewegt, der die die Röntgenstrahlungsdetektoren treffende Strahlung entsprechend seiner Dichte abschwächt. Die Intensität der entsprechend der Dichte geschwächten Strahlung wird mit den Röntgenstrahlungsdetektoren 14.3 bis 14.n erfaßt, die die entsprechenden Meßsignale S3 bis Sn an die Auswertanordnung 16 abgeben. Die Auswertanordnung vergleicht diese Meßsignale in den Funktionsblöcken 22.3 bis 22.n mit den den Dunkelströmen der Röntgenstrahlungsdetektoren 14.3 bis 14.n entsprechenden, gespeicherten Kompensationswerten jD,3 bis jD,n. Die Kompensationswerte ihrerseits werden in Berechnungsstufen 24.3 bis 24.n in Abhängigkeit von dem jeweils aktuellen Dunkelsignal SD des gegen die Röntgenstrahlung dauernd abgeschirmten Röntgenstrahlungsdetektors 14.1 korrigiert, wodurch eine Kompensation von in den Detektoren auftretenden Drifterscheinungen bewirkt wird. Die Wirkung von Alterungsprozessen der Detektoren oder von Wärmewanderungen ihrer Charakteristik wird damit zuverlässig ausgeschaltet. Die Komparatoren 22.3 bis 22.n geben an nachgeschaltete Berechnungsstufen 23.3 bis 23,n korrigierte Meßsignale S3,k bis Sn,k ab, die die die Detektoren 14.3 bis 14.n nach dem Durchgang durch den Strang treffende Röntgenstrahlung repräsentieren, die also der Strangdichte in der jeweils vom betreffenden Detektor erfaßten Stranghöhenposition entsprechen.For density measurement, a strand 1 is moved through the tube 6 in the measuring station 12, which attenuates the radiation striking the X-ray radiation detectors in accordance with its density. The intensity of the radiation weakened in accordance with the density is detected with the X-ray radiation detectors 14.3 to 14.n, which emit the corresponding measurement signals S 3 to S n to the evaluation arrangement 16. The evaluation arrangement compares these measurement signals in the function blocks 22.3 to 22.n with the stored compensation values j D, 3 to j D, n corresponding to the dark currents of the X-ray detectors 14.3 to 14.n. The compensation values in turn are calculated in calculation levels 24.3 to 24.n corrected as a function of the respectively current dark signal S D of the X-ray detector 14.1 which is permanently shielded from the X-radiation, whereby compensation for drift phenomena occurring in the detectors is effected. The effect of the aging processes of the detectors or of heat changes in their characteristics is thus reliably eliminated. The comparators 22.3 to 22.n give corrected measurement signals S 3, k to S n, k to the downstream calculation stages 23.3 to 23, n, which represent the X-rays which hit the detectors 14.3 to 14.n after passing through the strand, ie correspond to the strand density in the strand height position detected by the respective detector.

Gleichzeitig werden den Berechnungsstufen 23.3 bis 23.n Referenzsignale I3,k bis In,k übergeben. Diese Referenzsignale ergeben sich aus den in den Speichersektionen 21.3 bis 21.n hinterlegten Referenzwerten j0,3 bis j0,n, die in Korrekturstufen 25.3 bis 25.n in Abhängigkeit von dem aktuellen Referenzmeßsignal S2 bzw. S0 des dauernd mit der vollen Röntgenstrahlung beleuchteten Röntgenstrahlungsdetektors 14.2 korrigiert werden. Durch Vergleich mit dem in der Kompensationsstufe 24.2 in Abhängigkeit von dem Dunkelsignal SD des dauernd abgeschirmten Strahlungsempfängers 14.1 korrigierten, in der Speichersektion 19.2 als Konstante gespeicherten Referenzwert jD,2 des Detektors 14.2 in der Komparatorstufe 22.2 wird ein Korrektursignal S2,k gebildet, welches in den Korrekturstufen 25.3 bis 25.n zur Korrektur der Referenzwerte j0,3 bis j0,n genutzt wird. So wird durch den Einsatz des zusätzlichen Detektors 14.2, der dauernd die ungedämpfte Intensität der Röntgenstrahlungsquelle 7 empfängt und dessen Meßsignal S2 ein permanentes aktuelles Referenzsignal S0 darstellt, und durch den weiteren Detektor 14.1, der dauernd gegen die Röntgenstrahlungsquelle 7 abgeschirmt ist und stets ein Dunkelstromsignal SD als Kompensationssignal abgibt, erreicht, daß die Dichtemessung von Intensitätsschwankungen der Röntgenstrahlungsquelle 7, von Temperaturdriften und Alterungserscheinungen der Detektoren unabhängig ist.At the same time, reference signals I 3, k to I n, k are transferred to the calculation stages 23.3 to 23.n. These reference signals result from the reference values j 0.3 to j 0, n stored in the memory sections 21.3 to 21.n, which are stored in correction stages 25.3 to 25.n as a function of the current reference measurement signal S 2 or S 0 full X-ray illuminated X-ray detector 14.2 are corrected. A correction signal S 2, k is formed by comparison with the reference value j D, 2 of the detector 14.2 in the comparator stage 22.2, which is corrected in the compensation section 24.2 as a function of the dark signal S D of the permanently shielded radiation receiver 14.1 and is stored in the memory section 19.2 as a constant, which is used in correction stages 25.3 to 25.n to correct the reference values j 0.3 to j 0, n . Thus, by using the additional detector 14.2, which continuously receives the undamped intensity of the X-ray radiation source 7 and whose measurement signal S 2 represents a permanent current reference signal S 0 , and by the further detector 14.1, which is permanently shielded from the X-ray radiation source 7 and always on Outputs dark current signal S D as a compensation signal, achieved that the density measurement is independent of fluctuations in intensity of the X-ray source 7, temperature drifts and signs of aging of the detectors.

Die korrigierten Meßsignale S3,k bis Sn,k werden in den Berechnungsstufen 23.3 bis 23.n respektive mit den korrigierten Referenzsignalen I3,k bis In,k zu separaten Dichtesignalen D3 bis Dn verarbeitet, die jedes die Dichte in einer zugehörigen Stranghöhenposition repräsentieren. Das geschieht durch Logarithmierung des Verhältnisses (Quotienten) von Referenzsignal und korrigiertem Meßsignal. Die sich daraus ergebenden separaten Dichtesignale D3 bis Dn werden in einer Additionsstufe 26 addiert und als Dichtesignal 17 an die angeschlossene Steueranordnung 18 abgegeben. Gegebenenfalls kann auch der Mittelwert der separaten Dichtesignale D3 bis Dn als die Strangdichte repräsentierendes Dichtesignal gebildet werden. Das Logarithmieren der Einzelmeßwerte in den Berechnungsstufen 23 hat gegenüber der heute üblichen Logarithmierung des integrierten Dichtewertes den Vorteil, daß sich eine mathematisch korrekte und damit eine zuverlässigere und genauere Aussage über die Strangdichte im aktuell durchleuchteten Strangabschnitt ergibt.The corrected measurement signals S 3, k to S n, k become separate density signals in the calculation stages 23.3 to 23.n or with the corrected reference signals I 3, k to I n, k Processed D 3 to D n , each representing the density in an associated strand height position. This is done by logarithmizing the ratio (quotient) of the reference signal and the corrected measurement signal. The resulting separate density signals D 3 to D n are added in an addition stage 26 and output as a density signal 17 to the connected control arrangement 18. If necessary, the mean value of the separate density signals D 3 to D n can also be formed as a density signal representing the strand density. The logarithmization of the individual measured values in the calculation stages 23 has the advantage over the logarithmization of the integrated density value that is common today that a mathematically correct and thus a more reliable and more accurate statement about the strand density in the strand section currently being illuminated results.

Eine andere gemäß der Erfindung vorgesehene Möglichkeit besteht darin, die Quotienten der Referenzsignale und der zugehörigen korrigierten Meßsignale zunächst zu multiplizieren und das so gebildete Produkt zu logarithmieren, um das gewünschte Dichtesignal zu gewinnen.Another possibility provided according to the invention is to first multiply the quotients of the reference signals and the associated corrected measurement signals and logarithmize the product thus formed in order to obtain the desired density signal.

Die Ausdehnung der strahlungsempflndlichen Fläche der Röntgenstrahlungsdetektoren ist vorzugsweise sehr klein. So werden derzeit Detektoren bevorzugt, deren Strahlungsempfindliche Fläche in Längsrichtung des Strangs ca. 4 mm und quer zum Strang etwa 1 mm beträgt. Damit erfassen die einzelnen Detektoren Strangabschnitte sehr geringer Ausdehnung, in denen die Dichte wenigstens angenähert als homogen angenommen werden kann. Auch dies trägt wesentlich zur Genauigkeit der Meßergebnisse bei, weil die Logarithmierung der einzelnen Intensitätswerte ein mathematisch korrekter Auswertschritt ist, so daß Ergebnisverfälschungen verhindert werden. Außerdem führt diese Ausbildung der Detektoren zu einer hohen Auflösung.The extent of the radiation-sensitive area of the X-ray radiation detectors is preferably very small. For example, detectors are currently preferred whose radiation-sensitive area is approximately 4 mm in the longitudinal direction of the strand and approximately 1 mm transversely to the strand. The individual detectors thus detect strand sections of very little extent, in which the density can be assumed to be at least approximately homogeneous. This also contributes significantly to the accuracy of the measurement results because the logarithmization of the individual intensity values is a mathematically correct evaluation step, so that falsification of results is prevented. In addition, this design of the detectors leads to a high resolution.

Es ist bekannt, daß die weicheren Strahlungsanteile einer Röntgenstrahlung beim Durchgang durch eine Masse stärker absorbiert werden als die härteren, so daß ein größerer Anteil der härteren Röntgenstrahlung die Masse durchdringt. Diese Erscheinung wird auch als

Figure imgb0001
Aushärtung der Röntgenstrahlung" bezeichnet. Für ein bestimmtes durchleuchtetes Material können den gemessenen Intensitäten (Dichtesignalen) empirisch Korrekturwerte zugeordnet werden, welche den Einfluß der
Figure imgb0001
Aushärtung" auf die Dichtesignale kompensieren. Das ergibt eine weitere Verbesserung der Strangdichtemessung gemäß der Erfindung.It is known that the softer radiation components of an X-ray radiation are absorbed more strongly than the harder ones when they pass through a mass, so that a larger proportion of the harder X-ray radiation penetrates the mass. This phenomenon is also called
Figure imgb0001
Curing of the X-rays ". For a specific fluoroscopic Material can be empirically assigned correction values to the measured intensities (density signals), which determine the influence of the
Figure imgb0001
Compensate curing "on the density signals. This results in a further improvement of the strand density measurement according to the invention.

Claims (14)

Verfahren zum Bestimmen der Dichte eines Faserstrangs der tabakverarbeitenden Industrie, insbesondere eines Zigarettenstrangs, bei dem die Intensität einer den Strang durchdringenden Röntgenstrahlung erfaßt, ein der Intensität entsprechendes Meßsignal gebildet und das Meßsignal zu einem die Dichte des Strangs repräsentierenden Dichtesignal verarbeitet wird, dadurch gekennzeichnet, daß die Intensität der den Strang durchdringenden Röntgenstrahlung in einer Vielzahl von Stranghöhenpositionen separat erfaßt wird, daß den erfaßten Intensitäten entsprechende Meßsignale gebildet werden und daß alle Meßsignale zu einem einzigen Dichtesignal verarbeitet werden.Method for determining the density of a fiber strand of the tobacco processing industry, in particular a cigarette rod, in which the intensity of an X-ray beam penetrating the strand is detected, a measurement signal corresponding to the intensity is formed and the measurement signal is processed into a density signal representing the density of the strand, characterized in that the intensity of the X-rays penetrating the strand is detected separately in a plurality of strand height positions, that measurement signals corresponding to the detected intensities are formed and that all measurement signals are processed into a single density signal. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß in jeder Stranghöhenposition die Intensität eines einen Strangabschnitt mit vernachlässigbarer Dichteinhomogenität durchdringenden Teils der Röntgenstrahlung erfaßt wird.Method according to Claim 1, characterized in that the intensity of a part of the X-ray radiation penetrating a strand section with negligible density inhomogeneity is detected in each strand height position. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß zusätzlich die Intensität eines den Strang nicht durchdringenden Teils der Röntgenstrahlung als Referenzstrahlung separat erfaßt und ein entsprechendes Meßsignal als Referenz signal gebildet wird und daß dieses Referenzsignal mit den Meßsignalen zu einem Dichtesignal verarbeitet wird.Method according to Claim 1 or 2, characterized in that the intensity of a part of the X-radiation which does not penetrate the strand is separately detected as reference radiation and a corresponding measurement signal is formed as a reference signal, and in that this reference signal is processed with the measurement signals to form a density signal. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Meßsignale durch Summenbildung zu einem Dichtesignal verarbeitet werden.Method according to one of claims 1 to 3, characterized in that the measurement signals are processed to form a density signal by summation. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Meßsignale vor der Summenbildung logarithmiert werden.Method according to one of Claims 1 to 4, characterized in that the measurement signals are logarithmized before the sum is formed. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Meßsignale multipliziert werden und das Produkt logarithmiert wird.Method according to one of claims 1 to 4, characterized in that the measurement signals are multiplied and the product is logarithmic. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß wenigstens ein Röntgenstrahlungsdetektor gegen die Röntgenstrahlung abgeblendet wird, daß ein Dunkelstrom des abgeblendeten Detektors erfaßt und ein entsprechendes Dunkelsignal erzeugt wird und daß dieses Dunkelsignal bei der Bildung von Dichtesignalen aus den anderen Meßsignalen zur Kompensation von Drifteinflüssen genutzt wird.Method according to one of claims 1 to 6, characterized in that at least one X-ray detector is dimmed against the X-ray radiation, that a dark current of the dimmed detector is detected and a corresponding dark signal is generated, and that this dark signal is used to compensate for the formation of density signals from the other measurement signals is used by drift influences. Vorrichtung zum Bestimmen der Dichte eines Faserstrangs der tabakverarbeitenden Industrie, insbesondere eines Zigarettenstrangs, welche eine einer Strangführung zugeordnete Meßstation mit einer Röntgenstrahlungsquelle und einem der Röntgenstrahlungsquelle gegenüber zu ihr hin ausgerichteten Strahlungsempfänger zum Erfassen einer einen in der Strangführung bewegten Strang durchdringenden Röntgenstrahlung und zum Erzeugen entsprechender Meßsignale und eine mit dem Strahlungsempfänger verbundene Auswertanordnung zum Verarbeiten der Meßsignale zu die Strangdichte repräsentierenden Dichtesignalen aufweist, dadurch gekennzeichnet, daß der Strahlungsempfänger (12) als Linienarray (13) mit einer Vielzahl von in einer Reihe angeordneten Röntgenstrahlungsdetektoren (14.1 bis 14.n) zum Erfassen der Strangdichte in einer Vielzahl von Stranghöhenpositionen und zum Erzeugen entsprechender Meßsignale ( S1 bis Sn) ausgebildet ist und daß die Auswertanordnung (16) die Meßsignale zu einem Dichtesignal (17) verarbeitend ausgebildet ist.Device for determining the density of a fiber strand of the tobacco processing industry, in particular a cigarette rod, which has a measuring station associated with a strand guide with an X-ray radiation source and a radiation receiver oriented towards the X-ray radiation source for detecting an X-ray radiation penetrating a strand moving in the strand guide and for generating corresponding measurement signals and an evaluation arrangement connected to the radiation receiver for processing the measurement signals into density signals representing the strand density, characterized in that the radiation receiver (12) as a line array (13) with a plurality of X-ray radiation detectors (14.1 to 14.n) arranged in a row for detection the strand density in a plurality of strand height positions and for generating corresponding measurement signals (S 1 to S n ) is formed and that the evaluation arrangement (16) the measurement signals z u is designed to process a density signal (17). Vorrichtung nach Anspruch 8, dadurch gekennzeichnet, daß das Linienarray (13) wenigstens einen zusätzlichen Röntgenstrahlungsdetektor (14.2) aufweist, der einen den Strang (1) nicht durchdringenden Teil der Röntgenstrahlung erfaßt und ein entsprechendes Meßsignal (S2) als Referenzsignal (S0 ) erzeugt, und daß die Auswertanordnung (16) die Meßsignale (S3 bis Sn) in Abhängigkeit von diesem Referenzsignal (S0) korrigierend ausgebildet ist.Apparatus according to claim 8, characterized in that the line array (13) has at least one additional X-ray radiation detector (14.2) which detects a part of the X-ray radiation which does not penetrate the strand (1) and a corresponding measurement signal (S 2 ) as a reference signal (S 0 ) generated, and that the evaluation arrangement (16), the measurement signals (S 3 to S n ) in dependence on this reference signal (S 0 ) is corrective. Vorrichtung nach Anspruch 8 oder 9, dadurch gekennzeichnet, daß das Linienarray (13) wenigstens einen weiteren Röntgenstrahlungsdetektor (14.1) aufweist, der gegen die Röntgenstrahlung (8) abgeschirmt ist und ein seinem Dunkelstrom entsprechendes Dunkelsignal (SD) erzeugt und daß die Auswertanordnung (16) die Meßsignale (S3 bis Sn) und/oder das Referenzsignal (S0) zur Kompensation von Drifteinflüssen in Abhängigkeit von diesem Dunkelsignal (SD) korrigierend ausgebildet ist.Apparatus according to claim 8 or 9, characterized in that the line array (13) has at least one further X-ray radiation detector (14.1) which is shielded from the X-ray radiation (8) and generates a dark signal (S D ) corresponding to its dark current and that the evaluation arrangement ( 16) the measurement signals (S 3 to S n ) and / or the reference signal (S 0 ) for compensating drift influences as a function of this dark signal (S D ) is designed to be corrective. Vorrichtung nach einem der Ansprüche 8 bis 10, dadurch gekennzeichnet, daß die Auswertanordnung (16) aus den Meßsignalen (S3 bis Sn) der die den Strang (1) durchdringende Röntgenstrahlung erfassenden Detektoren (14.3 bis 14.n) die Summe bildend und die Summe zu einem die Dichte des Faserstrangs repräsentierenden Dichtesignal (17) verarbeitend ausgebildet ist.Device according to one of Claims 8 to 10, characterized in that the evaluation arrangement (16) forms the sum from the measurement signals (S 3 to S n ) of the detectors (14.3 to 14.n) which detect the X-rays penetrating the strand (1) and processing the sum to form a density signal (17) representing the density of the fiber strand. Vorrichtung nach einem der Ansprüche 8 bis 11, dadurch gekennzeichnet, daß die Auswertanordnung (16) die Meßsignale wenigstens der Detektoren (14.3 bis 14.n), welche die den Faserstrang (1) durchdringende Röntgenstrahlung erfassen, vor der Summenbildung logarithmierend ausgebildet ist.Device according to one of claims 8 to 11, characterized in that the evaluation arrangement (16) is designed to be logarithmic to the measurement signals of at least the detectors (14.3 to 14.n) which detect the X-ray radiation penetrating the fiber strand (1). Vorrichtung nach einen der Ansprüche 8 bis 11, dadurch gekennzeichnet, daß die Auswertanordnung (16) die Meßsignale wenigstens der Detektoren (14.3 bis 14.n), welche die den Faserstrang (1) durchdringende Röntgenstrahlung erfassen, multiplizierend und das Produkt logarithmierend ausgebildet ist.Device according to one of Claims 8 to 11, characterized in that the evaluation arrangement (16) multiplies the measurement signals of at least the detectors (14.3 to 14.n) which detect the X-rays penetrating the fiber strand (1) and the product is logarithmic. Vorrichtung nach einem der Ansprüche 8 bis 13, dadurch gekennzeichnet, daß die Röntgendetektoren (14.1 bis 14.n) des Linienarrays (13) so klein ausgebildet sind, daß die Dichte des von jedem Detektor erfaßten Strangbereichs im wesentlichen homogen erscheint.Device according to one of claims 8 to 13, characterized in that the x-ray detectors (14.1 to 14.n) of the line array (13) are so small that the density of the strand area detected by each detector appears essentially homogeneous.
EP97101524A 1996-02-15 1997-01-31 Method and apparatus for determining the density of a rod in the tobacco industry Expired - Lifetime EP0790006B1 (en)

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DE19605618 1996-02-15
DE19605618A DE19605618A1 (en) 1996-02-15 1996-02-15 Method and device for determining the density of a fiber strand of the tobacco processing industry

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Also Published As

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EP0790006B1 (en) 2002-04-17
DE19605618A1 (en) 1997-08-21
EP0790006A3 (en) 1999-06-09
JPH09224632A (en) 1997-09-02
ES2173348T3 (en) 2002-10-16
DE59707008D1 (en) 2002-05-23
US5762075A (en) 1998-06-09

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