EP0943087B1 - Device and method for detecting fluorescent and phosphorescent light - Google Patents

Device and method for detecting fluorescent and phosphorescent light Download PDF

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Publication number
EP0943087B1
EP0943087B1 EP97954730A EP97954730A EP0943087B1 EP 0943087 B1 EP0943087 B1 EP 0943087B1 EP 97954730 A EP97954730 A EP 97954730A EP 97954730 A EP97954730 A EP 97954730A EP 0943087 B1 EP0943087 B1 EP 0943087B1
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EP
European Patent Office
Prior art keywords
light
intensity
sheet material
emitted
emitted light
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EP97954730A
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German (de)
French (fr)
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EP0943087A1 (en
Inventor
Nikolai Lipkowitsch
Bernd Wunderer
Heinz-Philipp Hornung
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Giesecke and Devrient GmbH
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Giesecke and Devrient GmbH
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    • GPHYSICS
    • G07CHECKING-DEVICES
    • G07DHANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
    • G07D7/00Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
    • G07D7/06Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using wave or particle radiation
    • G07D7/12Visible light, infrared or ultraviolet radiation

Definitions

  • the invention describes an apparatus and a method for detection of fluorescent and phosphorescent light emitted from a sheet, such as e.g. Securities or banknotes.
  • Such a device is already known from US Pat. No. 3,473,027. These Device described has a lighting device that the Sheet material illuminated with ultraviolet excitation light. This is preferred Sheet material continuously illuminated by the ultraviolet excitation light. If required, clocked lighting of the sheet material is also possible.
  • the Light emitted by the sheet material is detected by means of a sensor. For this the emitted light is imaged on a prism by means of a lens system, which then breaks down the emitted light into certain wavelength ranges. The individual wavelength ranges are determined using a further lens system each mapped onto a detector, which is then an electrical one Output signal proportional to the intensity of the wavelength range.
  • a disadvantage of this known device is that the sheet material emitted light is not divided into fluorescent and phosphorescent parts can be.
  • a device and a method for detecting fluorescent and phosphorescent light emitted by an identification tag on a package is known from US-PS 3,592,326.
  • an optical scanner including lighting device described, in which the on conveyor belts transported packets by focused on a scan line Lamps are illuminated clocked during the transport movement.
  • the light emitted by the package or the identification mark is transmitted via a rotating mirror arrangement, whose axis of rotation parallel to the direction of transport runs and which is exactly above the said scan line one of two sensors via two prisms and assigned filters fed.
  • a rotating mirror arrangement whose axis of rotation parallel to the direction of transport runs and which is exactly above the said scan line
  • one of two sensors via two prisms and assigned filters fed.
  • the known device has a complex structure and also requires at least two sensors, what with a corresponding one Adjustment, calibration and maintenance requirements are connected.
  • the illumination and scanning aligned to the scan line is the excitation the phosphorescent identification tag only slightly, so that only a small amount for the detection of the phosphorescent emitted light Intensity is available, which enables precise, reproducible measurement is not ensured.
  • the invention is therefore based on the object of measuring very precisely Device and a method for the detection of fluorescent and phosphorescent To create light from a sheet, in which the sheet emitted light also with a common sensor in a fluorescent and a phosphorescent portion can be divided.
  • a sensor during the bright phase of the clocked Excitation light an intensity of the emitted light and during the Dark phase of the clocked excitation light a further intensity of emitted light detected.
  • the in the bright phase and in the dark phase of the clocked excitation light Intensities an intensity of the fluorescent light emitted and derived an intensity of the phosphorescent emitted light.
  • the intensity of the phosphorescent light emitted the intensity of the Dark phase and the intensity of the fluorescent emitted light is considered Difference of the intensity in the light phase and the intensity in the dark phase derived.
  • the sensor also detects the intensities of the emitted Light inside and in the direction of transport towards the end of the Illumination device illuminated area of the sheet material. additionally becomes the area of the sheet material illuminated by the lighting device chosen so large that it is a multiple of the desired resolution.
  • FIG. 1a shows a schematic diagram of a preferred embodiment of the invention Contraption.
  • a light-tight housing 10 with a there is a lighting device 20 in the translucent window 11 and two sensors 30 and 40.
  • the window 11 transmits both the Wavelength range of the excitation light as well as the wavelength range of the fluorescent and phosphorescent light emitted.
  • the lighting device 20 has a light-tight housing 21 with a Filter 22 on which the wavelength range of the fluorescent to be detected and phosphorescent emitted light is not transmitted.
  • a Filter 22 on which the wavelength range of the fluorescent to be detected and phosphorescent emitted light is not transmitted.
  • Control device is clocked appropriately. That from the excitation lamp 23 emitted light contains at least that for the excitation of the fluorescent and phosphorescent emitted light necessary wavelength range.
  • a gas discharge lamp is preferably used as the excitation lamp 23. which at least emits UV light.
  • the excitation lamp 23 also fluorescent lamps or gas discharge lamps without fluorescent be used.
  • the use of gas discharge lamps possible the light due to a reaction of excited noble gases emit with halogen.
  • the sensors 30 and 40 are constructed essentially analog.
  • Prefers have a detector array 31, 41 with which the material emitted by the sheet material Light in an electrical signal proportional to the intensity of the emitted Light is converted.
  • a detector array 31, 41 Photo diode arrays or CCD arrays can be used.
  • the detector array can detect only one track on the sheet material 31, 41 can also be replaced by a single detector. Is preferred the detector array 31, 41 is selected so that that over the entire width of the Sheet light emitted light can be detected in adjacent tracks can.
  • the sensors 30, 40 each have an optical system 33, 43, the one area of the sheet material, which is preferably smaller than the desired Resolution, images on a detector of the detector array 31, 41.
  • an optical System 33, 43 for example, lens systems can be used.
  • optical systems 33, 43 are preferably used, which at least have an imaging unit made of light-conducting material. The advantage of an imaging unit made of light-conducting material is that that they are much more compact compared to lens systems is.
  • a filter can be in the optical axis 34, 44 of a sensor 30, 40 32, 42 are provided. On the appropriate choice of the wavelength ranges the filter 32, 42 will be discussed below.
  • the optical axes 34, 44 of the sensors 30, 40 with respect to an angle ⁇ a perpendicular to the transport direction V rotated. Unwanted reflections at the window 11 are prevented by the translucent Anti-glare window 11 at least for light that is incident at the angle ⁇ is.
  • the sheet material 50 is brought to a transport system, not shown here the lighting device 20 and the sensors 30 and 40 in one with an arrow marked transport direction and a predetermined one Transport speed V transported past.
  • 1b shows the intensity of the generated by the lighting device Excitation light in relative units compared to the spatial extent in the direction of transport.
  • Area B initially increases the intensity of the excitation light peaks and then drops again at the other end of the range.
  • the sensors 30, 40 are symmetrical to the maximum of the intensity of the excitation light arranged and detect the intensities of the emitted Light within the illuminated area B. In the illustrated embodiment sensors 30 and 40 detect the intensity of the emitted Light where the intensity of the excitation light has dropped to half is.
  • a Clock T generates whose frequency is the quotient of the transport speed V of the transport system and a desired local resolution A results in the direction of transport.
  • T V / A applies.
  • the bank note 50 is shown with the clock T.
  • the above definition of the clock frequency of the clock T ensures that it is independent of the transport speed V in each case the logical 1 or the logical 0 of the clock T linked to a specific location of the banknote 50 is.
  • the desired resolution A contains one bar of the bar T.
  • the sheet material 50 To detect the fluorescent and phosphorescent light emitted by the Sheet material 50, this is first of all with a clocked excitation light Illumination device 20 illuminated.
  • the light emitted by the sheet material 50 is from the sensor 30 within the illuminated area B in the transport direction towards the end of the illuminated area, preferably behind the maximum the intensity of the excitation light is detected.
  • each area of resolution A during the transportation of the Sheet material 50 over several cycles of the cycle T from the excitation light of the lighting device 20 illuminated. Since the detection of the intensity of the emitted light by the sensor 30 only in the transport direction towards the end of the illuminated area, preferably behind the maximum of the intensity the excitation light is detected, it is ensured that each area A the sheet material 50 receives a relatively long pre-illumination with high intensity, before the emitted light is detected by sensor 30.
  • a long pre-lighting with high intensity leads to the fact that the initial intensity I 0 of a phosphorescent emitting substance is relatively high. Since the intensity of the emitted light from phosphorescent substances depends on the initial intensity I 0 and decreases exponentially with time, a high initial intensity I 0 is necessary for an accurate measurement.
  • the decay time ⁇ up to half the intensity and the value a are properties of the phosphorescent emitting substance.
  • the time sequences in the detection of the cut light are shown in FIG. 2.
  • the clocks T 1 to T 3 are clocks at different transport speeds V and are determined according to the above equation.
  • the light phase or the dark phase of the clocked excitation light are generated with the clock L.
  • the excitation lamp 23 is clocked with a specific, freely selectable clock L, which, however, has a higher frequency than the clock T.
  • the clock L sends a specific number of logic lines to the control unit of the excitation lamp 23.
  • the excitation lamp 23 At every logic 1 of the clock L, the excitation lamp 23 generates a light pulse.
  • the intensity R of the emitted light is thus approximately during the bright phase constant and contains all wavelength ranges of the emitted Light.
  • a filter is preferred in the optical axis 34 of the sensor 30 32 provided that only the wavelength range of the fluorescent and transmitted phosphorescent light.
  • the clock D controls the time of detection of the emitted light the sensor 30.
  • This clock D contains two areas with a logical 1. The only the area controls the detection of the emitted light in the area of the bright phase and the second area controls the detection in the dark phase area.
  • the time interval between the first area and the second The range of clock D is chosen to be constant.
  • the time interval of the The beginning of the first area of the clock T at the beginning of the clock D is constant.
  • the time ranges of clock D and their position in the bright or dark phase can in principle be chosen arbitrarily. Prefers however, the position and width of the first area of the clock D is chosen so that the intensity of the emitted light in the bright phase of a clock is measured during the last light pulse.
  • the location of the second area the clock D is placed so that the intensity of the emitted light in the dark phase after a constant period after the last one Light pulse is measured.
  • the constant time period is chosen so that the detection of the intensity of the emitted light in the dark phase takes place within the shortest possible cycle T.
  • the clock T since the clock T, as described above, from the transport speed V depends on the sheet material, this varies with a variation of the transport speed V. Since the method described above for detecting the intensity of the emitted light in the light or dark phase only from Depends on the beginning of the clock T, a slowdown of the clock T, i.e. a slowing down of the transport speed V, within certain limits be tolerated. Because the detection of the emitted light in the dark phase measured after a constant period of time after the last light pulse is, the reproducibility of the intensity of the emitted light is also in the dark phase despite the exponential drop in the intensity of the phosphorescent emitted light guaranteed.
  • Detected intensities are fluorescence intensities emitted light and an intensity of the phosphorescent emitted Light derived.
  • the intensity of the phosphorescent emitted light correspond to the intensity in the dark phase.
  • the intensity of the fluorescent light emitted can be the difference of the Intensity in the light phase and intensity in the dark phase are derived become.
  • the second sensor 40 that emitted by the sheet material can be Light can be detected in several different wavelength ranges.
  • a filter 42 is provided in the sensor 40 in the optical axis 44. which is only a sub-range of the wavelength range of the fluorescent and emitted phosphorescent light. Because the sensors 30, 40 symmetrical to the maximum of the intensity of the lighting device 20 are arranged, the sensor 40 detects the intensity of the emitted Light in the transport direction at the beginning of the illuminated area, preferred before the maximum of the intensity of the excitation light. From this follows that only a negligibly small pre-illumination of the phosphorescent Substance in the detection of the emitted light by the sensor 40 has taken place.
  • That detected by the sensor 40 in the dark phase emitted light can essentially only unwanted stray light be so that the intensity of the light detected in the dark phase of sensor 40, for example for normalizing all other measured Intensities can be used. That from sensor 40 during the light phase Detected emitted light thus contains fluorescent light that restricted to a certain wavelength range by the filter 42 becomes.
  • the senor can 30 an overall intensity of the fluorescent light emitted and from the sensor 40 an intensity of a specific waveband of the fluorescent emitted Derive light.
  • the difference between the detected Total intensity of the sensor 30 and the detected intensity of the sensor 40 can also be an intensity of the fluorescent light emitted in the to the wavelength range of the sensor 40 complementary wavelength range derived.
  • the sensor 30 detects the intensity of the phosphorescent emitted light.
  • the derived ones can be derived from clock T Intensities a place with the desired resolution A on the banknote 50 assign.
  • an intensity curve of the emitted light is broken down according to wavelength ranges.
  • the intensity profile I F is detected by the sensor 30 in the light phase, which contains the entire wavelength range of the emitted light.
  • the sensor 40 detects the intensity curve I R , which here, for example, only contains the red wavelength range of the emitted light.
  • the intensity curve I G of the yellow-green emitted light is the difference between the intensity curve I F and the intensity curve I R.
  • an intensity curve I P is obtained for the light emitted in the dark phase, which is shown in FIG. 3b.
  • the intensities for phosphorescent light and fluorescent light in different wavelength ranges are then derived from the intensity profiles.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
  • Inspection Of Paper Currency And Valuable Securities (AREA)
  • Luminescent Compositions (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Abstract

The apparatus has an illuminating device for illuminating sheet material with clocked excitation light. Both during the light phase of clocked excitation light and during the dark phase of clocked excitation light a sensor detects an intensity of the light emitted by the sheet material in each case. In an evaluation device an intensity of fluorescently emitted light and an intensity of phosphorescently emitted light are derived from the intensities detected in the light phase and in the dark phase of clocked excitation light. In order to ensure long preillumination with high intensity, the sensor preferably detects the intensities of emitted light within, and toward the end (in the transport direction) of, the area of the sheet material illuminated by the illuminating device. Additionally the illuminated area of the sheet material is selected to be so great that it is a multiple of the desired resolution.

Description

Die Erfindung beschreibt eine Vorrichtung und ein Verfahren zur Detektion von fluoreszent und phosphoreszent emittiertem Licht eines Blattgutes, wie z.B. Wertpapiere oder Banknoten.The invention describes an apparatus and a method for detection of fluorescent and phosphorescent light emitted from a sheet, such as e.g. Securities or banknotes.

Eine solche Vorrichtung ist bereits aus der US-PS 3,473,027 bekannt. Die dort beschriebene Vorrichtung weist eine Beleuchtungseinrichtung auf, die das Blattgut mit ultraviolettem Anregungslicht beleuchtet. Bevorzugt wird das Blattgut von dem ultravioletten Anregungslicht kontinuierlich beleuchtet. Bei Bedarf ist auch eine getaktete Beleuchtung des Blattguts möglich. Das vom Blattgut emittierte Licht wird mittels eines Sensors detektiert. Hierzu wird das emittierte Licht mittels eines Linsensystems auf ein Prisma abgebildet, das das emittierte Licht dann in bestimmte Wellenlängenbereiche zerlegt. Die einzelnen Wellenlängenbereiche werden mittels eines weiteren Linsensystems jeweils auf einen Detektor abgebildet, der dann ein elektrisches Signal proportional zur Intensität des Wellenlängenbereichs abgibt. Um das Blattgut entlang einer Spur mit einer gewünschten Auflösung zu detektieren, wird das Blattgut von einem Transportsystem entlang einer Transportrichtung an der Beleuchtungseinrichtung und an dem Sensor vorbeitransportiert.Such a device is already known from US Pat. No. 3,473,027. These Device described has a lighting device that the Sheet material illuminated with ultraviolet excitation light. This is preferred Sheet material continuously illuminated by the ultraviolet excitation light. If required, clocked lighting of the sheet material is also possible. The Light emitted by the sheet material is detected by means of a sensor. For this the emitted light is imaged on a prism by means of a lens system, which then breaks down the emitted light into certain wavelength ranges. The individual wavelength ranges are determined using a further lens system each mapped onto a detector, which is then an electrical one Output signal proportional to the intensity of the wavelength range. To do that To detect sheet material along a track with a desired resolution, is the sheet material from a transport system along a transport direction transported past the lighting device and the sensor.

Ein Nachteil dieser bekannten Vorrichtung ist es, daß das vom Blattgut emittierte Licht nicht in fluoreszente und phosphoreszente Anteile aufgeteilt werden kann.A disadvantage of this known device is that the sheet material emitted light is not divided into fluorescent and phosphorescent parts can be.

Eine Vorrichtung und ein Verfahren zum Detektieren von fluoreszent und phosphoreszent emittiertem Licht einer Identifikationsmarke auf einem Paket ist aus der US-PS 3,592,326 bekannt. Dort ist im Zusammenhang mit einer Paketvereinzelungs- und -ausrichtanlage eine optische Abtasteinrichtung einschließlich Beleuchtungseinrichtung beschrieben, bei welcher die auf Förderbändern transportierten Pakete durch auf eine Abtastlinie fokussierte Lampen während der Transportbewegung getaktet beleuchtet werden. Das vom Paket bzw. der Identifikationsmarke emittierte Licht wird über eine sich drehende Spiegelanordnung, deren Drehachse parallel zur Transportrichtung verläuft und die sich genau oberhalb der genannten Abtastlinie berindet über zwei Prismen und zugeordnete Filter jeweils einem von zwei Sensoren zugeführt. Dabei ist der eine Sensor für die Detektion von Reflexion und Fluoreszenz bei eingeschalteter Beleuchtung und der andere Sensor für das Feststellen von phosphoreszent emittiertem Licht bei ausgeschalteter Beleuchtung zuständig.A device and a method for detecting fluorescent and phosphorescent light emitted by an identification tag on a package is known from US-PS 3,592,326. There is related to one Parcel separation and alignment system an optical scanner including lighting device described, in which the on conveyor belts transported packets by focused on a scan line Lamps are illuminated clocked during the transport movement. The light emitted by the package or the identification mark is transmitted via a rotating mirror arrangement, whose axis of rotation parallel to the direction of transport runs and which is exactly above the said scan line one of two sensors via two prisms and assigned filters fed. Here is one sensor for the detection of reflection and Fluorescence with the lights on and the other sensor for that Detection of phosphorescent emitted light when the lighting is switched off responsible.

Die bekannte Vorrichtung weist zum einen einen aufwendigen Aufbau auf und benötigt darüber hinaus mindestens zwei Sensoren, was mit einem entsprechenden Justage-, Kalibrier- und Wartungsbedarf verbunden ist. Durch die auf die Abtastlinie ausgerichtete Beleuchtung und Abtastung ist die Anregung der phosphoreszent strahlenden Identifikationsmarke nur gering, so daß für die Detektion des phosphoreszent emittierten Lichts nur eine geringe Intensität zur Verfügung steht, wodurch ein exaktes, reproduzierbares Messen nicht sichergestellt ist.The known device has a complex structure and also requires at least two sensors, what with a corresponding one Adjustment, calibration and maintenance requirements are connected. By the illumination and scanning aligned to the scan line is the excitation the phosphorescent identification tag only slightly, so that only a small amount for the detection of the phosphorescent emitted light Intensity is available, which enables precise, reproducible measurement is not ensured.

Der Erfindung liegt daher die Aufgabe zugrunde, eine sehr genau messende Vorrichtung und ein Verfahren zur Detektion von fluoreszentem und phosphoreszentem Licht eines Blattgutes zu schaffen, bei der das vom Blattgut emittierte Licht auch mit einem gemeinsamen Sensor in einen fluoreszenten und einen phosphoreszenten Anteil aufgeteilt werden kann. The invention is therefore based on the object of measuring very precisely Device and a method for the detection of fluorescent and phosphorescent To create light from a sheet, in which the sheet emitted light also with a common sensor in a fluorescent and a phosphorescent portion can be divided.

Die Aufgabe wird durch die Merkmale der unabhängigen Ansprüche gelöst, wobei die abhängigen Ansprüche vorteilhafte Ausführungsformen darstellen.The task is characterized by the characteristics of the independent Claims resolved, the dependent Represent claims advantageous embodiments.

Erfindungsgemäß wird von einem Sensor während der Hellphase des getakteten Anregungslichts eine Intensität des emittierten Lichts und während der Dunkelphase des getakteten Anregungslichts eine weitere Intensität des emittierten Lichts detektiert. In einer Auswerteeinrichtung wird aus den in der Hellphase und in der Dunkelphase des getakteten Anregungslichtes detektierten Intensitäten eine Intensität des fluoreszent emittierten Lichts und eine Intensität des phosphoreszent emittierten Lichts abgeleitet. Hierbei entspricht die Intensität des phosphoreszent emittierten Lichts der Intensität der Dunkelphase und die Intensität des fluoreszent emittierten Lichts wird als Differenz der Intensität in der Hellphase und der Intensität in der Dunkelphase abgeleitet. Außerdem detektiert der Sensor die Intensitäten des emittierten Lichts innerhalb und in Transportrichtung gegen Ende des von der Beleuchtungseinrichtung beleuchteten Bereichs des Blattgutes. Zusätzlich wird der von der Beleuchtungseinrichtung beleuchtete Bereich des Blattgutes so groß gewählt, daß er ein Mehrfaches der gewünschten Auflösung beträgt. According to the invention, a sensor during the bright phase of the clocked Excitation light an intensity of the emitted light and during the Dark phase of the clocked excitation light a further intensity of emitted light detected. In an evaluation device, the in the bright phase and in the dark phase of the clocked excitation light Intensities an intensity of the fluorescent light emitted and derived an intensity of the phosphorescent emitted light. Here corresponds to the intensity of the phosphorescent light emitted the intensity of the Dark phase and the intensity of the fluorescent emitted light is considered Difference of the intensity in the light phase and the intensity in the dark phase derived. The sensor also detects the intensities of the emitted Light inside and in the direction of transport towards the end of the Illumination device illuminated area of the sheet material. additionally becomes the area of the sheet material illuminated by the lighting device chosen so large that it is a multiple of the desired resolution.

Hierdurch wird erreicht, daß die Intensität des phosphoreszent emittierten Lichts relativ groß wird, da eine möglichst lange Vorbeleuchtung mit hoher Intensität gewährleistet ist.This ensures that the intensity of the phosphorescent emitted Light becomes relatively large because the longest possible lighting with high Intensity is guaranteed.

Eine bevorzugte Ausführungsform der erfindungsgemäßen Vorrichtung sowie die Durchführung des erfindungsgemäßen Verfahrens wird im folgenden anhand der Figuren näher erläutert. Es zeigen:

Fig. 1
Prinzipskizze der Vorrichtung einschließlich der Intensität der Beleuchtungseinrichtung,
Fig. 2
Prinzipskizze der Taktverhältnisse,
Fig. 3
Intensitätsverläufe des emittierten Lichts.
A preferred embodiment of the device according to the invention and the implementation of the method according to the invention are explained in more detail below with reference to the figures. Show it:
Fig. 1
Principle sketch of the device including the intensity of the lighting device,
Fig. 2
Principle sketch of the clock ratios,
Fig. 3
Intensity curves of the emitted light.

Fig. 1a zeigt eine Prinzipskizze einer bevorzugten Ausführungsform der erfindungsgemäßen Vorrichtung. In einem lichtdichtem Gehäuse 10 mit einem lichtdurchlässigem Fenster 11 befindet sich eine Beleuchtungseinrichtung 20 sowie zwei Sensoren 30 und 40. Das Fenster 11 transmittiert sowohl den Wellenlängenbereich des Anregungslichtes als auch den Wellenlängenbereich des fluoreszent und phosphoreszent emittierten Lichts.1a shows a schematic diagram of a preferred embodiment of the invention Contraption. In a light-tight housing 10 with a there is a lighting device 20 in the translucent window 11 and two sensors 30 and 40. The window 11 transmits both the Wavelength range of the excitation light as well as the wavelength range of the fluorescent and phosphorescent light emitted.

Die Beleuchtungseinrichtung 20 weist ein lichtdichtes Gehäuse 21 mit einem Filter 22 auf, der den Wellenlängenbereich des zu detektierenden fluoreszent und phosphoreszent emittierten Lichts nicht transmittiert. In dem Gehäuse 21 befindet sich eine Anregungslampe 23, die über eine hier nicht dargestellte Steuereinrichtung geeignet getaktet wird. Das von der Anregungslampe 23 emittierte Licht enthält zumindest den für die Anregung des fluoreszent und phosphoreszent emittierten Lichts notwendigen Wellenlängenbereich. The lighting device 20 has a light-tight housing 21 with a Filter 22 on which the wavelength range of the fluorescent to be detected and phosphorescent emitted light is not transmitted. In the case 21 there is an excitation lamp 23, which is not shown here Control device is clocked appropriately. That from the excitation lamp 23 emitted light contains at least that for the excitation of the fluorescent and phosphorescent emitted light necessary wavelength range.

Als Anregungslampe 23 wird bevorzugt eine Gasentladungslampe verwendet, die zumindest UV-Licht emittiert. Generell können als Anregungslampe 23 auch Leuchtstofflampen bzw. Gasentladungslampen ohne Leuchtstoff verwendet werden. Weiterhin ist eine Verwendung von Gasentladungslampen möglich, die Licht aufgrund einer Reaktion von angeregten Edelgasen mit Halogen emittieren.A gas discharge lamp is preferably used as the excitation lamp 23. which at least emits UV light. Generally can be used as an excitation lamp 23 also fluorescent lamps or gas discharge lamps without fluorescent be used. Furthermore, the use of gas discharge lamps possible the light due to a reaction of excited noble gases emit with halogen.

Die Sensoren 30 und 40 sind im wesentlichen analog aufgebaut. Bevorzugt weisen Sie ein Detektorarray 31, 41 auf, mit dem das vom Blattgut emittierte Licht in ein elektrisches Signal proportional zur Intensität des emittierten Lichts umgewandelt wird. Als Detektorarray 31, 41 können beispielsweise Fotodiodenarrays oder CCD-Arrays verwendet werden. Soll beispielsweise nur eine Spur auf dem Blattgut detektiert werden, so kann das Detektorarray 31, 41 auch durch einen einzelnen Detektor ersetzt werden. Bevorzugt wird das Detektorarray 31, 41 so ausgewählt, daß das über die gesamte Breite des Blattguts emittierte Licht in aneinanderliegenden Spuren detektiert werden kann.The sensors 30 and 40 are constructed essentially analog. Prefers have a detector array 31, 41 with which the material emitted by the sheet material Light in an electrical signal proportional to the intensity of the emitted Light is converted. For example, as a detector array 31, 41 Photo diode arrays or CCD arrays can be used. For example the detector array can detect only one track on the sheet material 31, 41 can also be replaced by a single detector. Is preferred the detector array 31, 41 is selected so that that over the entire width of the Sheet light emitted light can be detected in adjacent tracks can.

Weiterhin weisen die Sensoren 30, 40 jeweils ein optisches System 33, 43 auf, das einen Bereich des Blattguts, der bevorzugt kleiner ist als die gewünschte Auflösung, auf einen Detektor des Detektorarrays 31, 41 abbildet. Als optisches System 33, 43 können beispielsweise Linsensysteme verwendet werden. Bevorzugt werden jedoch optische Systeme 33, 43 verwendet, die mindestens eine Abbildungseinheit aus lichtleitendern Material aufweisen. Der Vorteil einer Abbildungseinheit aus lichtleitendem Material besteht darin, daß diese im Vergleich zu Linsensystemen wesentlich kompakter aufgebaut ist. Furthermore, the sensors 30, 40 each have an optical system 33, 43, the one area of the sheet material, which is preferably smaller than the desired Resolution, images on a detector of the detector array 31, 41. As an optical System 33, 43, for example, lens systems can be used. However, optical systems 33, 43 are preferably used, which at least have an imaging unit made of light-conducting material. The The advantage of an imaging unit made of light-conducting material is that that they are much more compact compared to lens systems is.

Weiterhin können in der optischen Achse 34, 44 eines Sensors 30, 40 ein Filter 32, 42 vorgesehen werden. Auf die geeignete Wahl der Wellenlängenbereiche der Filter 32, 42 wird im folgenden noch eingegangen.Furthermore, a filter can be in the optical axis 34, 44 of a sensor 30, 40 32, 42 are provided. On the appropriate choice of the wavelength ranges the filter 32, 42 will be discussed below.

Um einen kompakten Aufbau der Vorrichtung zu gewährleisten, sind die optischen Achsen 34, 44 der Sensoren 30, 40 um einen Winkel α gegenüber einer Senkrechten zur Transportrichtung V gedreht. Unerwünschte Reflexionen am Fenster 11 werden dadurch verhindert, daß das lichtdurchlässige Fenster 11 zumindest für Licht, das unter dem Winkel α einfällt, entspiegelt ist. Zusätzlich besteht der Filter 22 aus zwei Schenkeln, die jeweils in einem festen Winkel β zu einer Senkrechten zur Transportrichtung angeordnet sind. Der Winkel β ergibt sich zu β = 90 ° - α.To ensure a compact structure of the device, the optical axes 34, 44 of the sensors 30, 40 with respect to an angle α a perpendicular to the transport direction V rotated. Unwanted reflections at the window 11 are prevented by the translucent Anti-glare window 11 at least for light that is incident at the angle α is. In addition, the filter 22 consists of two legs, each in one fixed angle β to a perpendicular to the direction of transport are. The angle β results in β = 90 ° - α.

Das Blattgut 50 wird mit einem hier nicht dargestellten Transportsystem an der Beleuchtungseinrichtung 20 und den Sensoren 30 und 40 in einer mit einem Pfeil gekennzeichneten Transportrichtung und einer vorgegebenen Transportgeschwindigkeit V vorbeitransportiert.The sheet material 50 is brought to a transport system, not shown here the lighting device 20 and the sensors 30 and 40 in one with an arrow marked transport direction and a predetermined one Transport speed V transported past.

Die Fig. 1b zeigt die von der Beleuchtungseinrichtung erzeugte Intensität des Anregungslichtes in relativen Einheiten gegenüber der räumlichen Ausdehnung in Transportrichtung. In dem von der Beleuchtungseinrichtung beleuchteten Bereich B steigt die Intensität des Anregungslichts zunächst auf ein Maximum an und fällt dann am anderen Ende des Bereichs wieder ab. Die Sensoren 30, 40 sind symmetrisch zum Maximum der Intensität des Anregungslichts angeordnet und detektieren die Intensitäten des emittierten Lichts innerhalb des beleuchteten Bereichs B. In der dargestellten Ausführungsform detektieren die Sensoren 30 und 40 die Intensität des emittierten Lichtes dort, wo die Intensität des Anregungslichts auf die Hälfte abgesunken ist. 1b shows the intensity of the generated by the lighting device Excitation light in relative units compared to the spatial extent in the direction of transport. In the illuminated by the lighting device Area B initially increases the intensity of the excitation light peaks and then drops again at the other end of the range. The sensors 30, 40 are symmetrical to the maximum of the intensity of the excitation light arranged and detect the intensities of the emitted Light within the illuminated area B. In the illustrated embodiment sensors 30 and 40 detect the intensity of the emitted Light where the intensity of the excitation light has dropped to half is.

Um die von einem der Sensoren 30, 40 detektierte Intensität einem bestimmten Ort in Transportrichtung auf dem Blattgut zuordnen zu können, wird ein Takt T erzeugt, dessen Frequenz sich als Quotient der Transportgeschwindigkeit V des Transportsystems und einer gewünschten örtlichen Auflösung A in Transportrichtung ergibt. Es gilt T = V/A. Beispielsweise für eine Transportgeschwindigkeit von V = 10 m/s und einer gewünschten Auflösung A von 2 mm ergibt sich eine Taktfrequenz T = 5 kHz. Bevorzugt weist der Takt für eine halbe Pulsdauer P = 1/T eine logische 1 und für die andere Hälfte der Pulsdauer eine logische 0 auf.By a certain amount of the intensity detected by one of the sensors 30, 40 To be able to assign a location on the sheet material in the direction of transport is a Clock T generates whose frequency is the quotient of the transport speed V of the transport system and a desired local resolution A results in the direction of transport. T = V / A applies. For example, for a Transport speed of V = 10 m / s and a desired resolution A of 2 mm results in a clock frequency T = 5 kHz. Preferably points the clock for half a pulse duration P = 1 / T is a logical 1 and for the other Half of the pulse duration a logical 0.

In Fig. 1c und 1d ist die Banknote 50 mit dem Takt T dargestellt. Durch die obige Definition der Taktfrequenz des Taktes T ist gewährleistet, daß unabhängig von der Transportgeschwindigkeit V jeweils die logische 1 bzw. die logische 0 des Taktes T mit einem bestimmten Ort der Banknote 50 verknüpft ist. Die gewünschte Auflösung A enthält jeweils einen Takt des Taktes T.1c and 1d, the bank note 50 is shown with the clock T. Through the The above definition of the clock frequency of the clock T ensures that it is independent of the transport speed V in each case the logical 1 or the logical 0 of the clock T linked to a specific location of the banknote 50 is. The desired resolution A contains one bar of the bar T.

Zur Detektion des fluoreszent und phosphoreszent emittierten Lichtes des Blattgutes 50 wird dieses zunächst mit einem getakteten Anregungslicht der Beleuchtungseinrichtung 20 beleuchtet. Das vom Blattgut 50 emittierte Licht wird vom Sensor 30 innerhalb des beleuchteten Bereichs B in Transportrichtung gegen Ende des beleuchteten Bereichs, bevorzugt hinter dem Maximum der Intensität des Anregungslichtes detektiert.To detect the fluorescent and phosphorescent light emitted by the Sheet material 50, this is first of all with a clocked excitation light Illumination device 20 illuminated. The light emitted by the sheet material 50 is from the sensor 30 within the illuminated area B in the transport direction towards the end of the illuminated area, preferably behind the maximum the intensity of the excitation light is detected.

Da der beleuchtete Bereich B wesentlich größer ist als die gewünschte Auflösung A wird jeder Bereich der Auflösung A während des Transports des Blattguts 50 über mehrere Takte des Taktes T vom Anregungslicht der Beleuchtungseinrichtung 20 beleuchtet. Da die Detektion der Intensität des emittierten Lichtes durch den Sensor 30 erst in Transportrichtung gegen Ende des beleuchteten Bereichs, bevorzugt hinter dem Maximum der Intensität des Anregungslichts detektiert wird, ist gewährleistet, daß jeder Bereich A des Blattguts 50 eine relativ lange Vorbeleuchtung mit hoher Intensität erhält, bevor das emittierte Licht vom Sensor 30 detektiert wird.Since the illuminated area B is much larger than the desired resolution A is each area of resolution A during the transportation of the Sheet material 50 over several cycles of the cycle T from the excitation light of the lighting device 20 illuminated. Since the detection of the intensity of the emitted light by the sensor 30 only in the transport direction towards the end of the illuminated area, preferably behind the maximum of the intensity the excitation light is detected, it is ensured that each area A the sheet material 50 receives a relatively long pre-illumination with high intensity, before the emitted light is detected by sensor 30.

Eine lange Vorbeleuchtung mit hoher Intensität führt dazu, daß die Anfangsintensität I0 eines phosphoreszent emittierenden Stoffes relativ hoch ist. Da die Intensität des emittierten Lichts von phosphoreszenten Stoffen von der Anfangsintensität I0 abhängt und mit der Zeit exponentiell abfällt, ist für eine genaue Messung eine hohe Anfangsintensität I0 notwendig. Die Intensität des emittierten Lichts eines phosphoreszenten Stoffes in Abhängigkeit von der Zeit genügt der Gleichung I (t) = I0/(1 + (t/τ)a). Die Abklingzeit τ bis zur halben Intensität sowie der Wert a sind Eigenschaften des phosphoreszent emittierenden Stoffes.A long pre-lighting with high intensity leads to the fact that the initial intensity I 0 of a phosphorescent emitting substance is relatively high. Since the intensity of the emitted light from phosphorescent substances depends on the initial intensity I 0 and decreases exponentially with time, a high initial intensity I 0 is necessary for an accurate measurement. The intensity of the emitted light of a phosphorescent substance as a function of time satisfies the equation I (t) = I 0 / (1 + (t / τ) a ). The decay time τ up to half the intensity and the value a are properties of the phosphorescent emitting substance.

Die zeitlichen Abläufe bei der Detektion des ernittierten Lichts sind in der Fig. 2 dargestellt. Die Takte T1 bis T3 sind Takte zu unterschiedlichen Transportgeschwindigkeiten V und werden nach der obigen Gleichung bestimmt. Die Hellphase bzw. die Dunkelphase des getakteten Anregungslichtes werden mit dem Takt L erzeugt. In der Hellphase wird die Anregungslampe 23 mit einem bestimmten, frei wählbaren Takt L getaktet, der jedoch eine höhere Frequenz als der Takt T aufweist. Zu Beginn einer logischen 1 des Taktes T sendet der Takt L eine bestimmte Anzahl von logischen len an das Steuergerät der Anregungslampe 23. Bei jeder logischen 1 des Taktes L erzeugt die Anregungslampe 23 einen Lichtpuls. Es entsteht somit in der Hellphase ein Anregungslicht, das eine bestimmte Anzahl von Lichtpulsen aufweist, die zu Beginn des Taktes T ausgesendet werden. Für den Rest des Taktes T liefert der Takt L eine logische 0 und es wird kein Anregungslicht von der Anregungslampe 23 emittiert wird. The time sequences in the detection of the cut light are shown in FIG. 2. The clocks T 1 to T 3 are clocks at different transport speeds V and are determined according to the above equation. The light phase or the dark phase of the clocked excitation light are generated with the clock L. In the light phase, the excitation lamp 23 is clocked with a specific, freely selectable clock L, which, however, has a higher frequency than the clock T. At the beginning of a logic 1 of the clock T, the clock L sends a specific number of logic lines to the control unit of the excitation lamp 23. At every logic 1 of the clock L, the excitation lamp 23 generates a light pulse. An excitation light thus arises in the bright phase, which has a certain number of light pulses which are emitted at the beginning of the cycle T. For the rest of the clock T, the clock L supplies a logic 0 and no excitation light is emitted by the excitation lamp 23.

Die Intensität R des emittierten Lichtes ist somit während der Hellphase annähernd konstant und enthält alle Wellenlängenbereiche des emittierten Lichtes. Bevorzugt wird in der optischen Achse 34 des Sensors 30 ein Filter 32 vorgesehen, der lediglich den Wellenlängenbereich des fluoreszent und phosphoreszent emittierten Lichtes transmittiert.The intensity R of the emitted light is thus approximately during the bright phase constant and contains all wavelength ranges of the emitted Light. A filter is preferred in the optical axis 34 of the sensor 30 32 provided that only the wavelength range of the fluorescent and transmitted phosphorescent light.

In der nach dem letzten Lichtpuls des Anregungslichtes einsetzenden Dunkelphase ist lediglich noch die Intensität des phosphoreszent emittierten Lichts vorhanden, die, abhängig vom gewählten Stoff, entsprechend dem oben angegebenen Potenzgesetz abfällt.In the dark phase after the last light pulse of the excitation light is only the intensity of the phosphorescent emitted Light available, which, depending on the selected fabric, according to the above the power law drops.

Der Takt D steuert den Zeitpunkt der Detektion des emittierten Lichts durch den Sensor 30. Dieser Takt D enthält zwei Bereiche mit einer logischen 1. Der erst Bereich steuert die Detektion des emittierten Lichts im Bereich der Hellphase und der zweite Bereich steuert die Detektion im Bereich der Dunkelphase. Der zeitliche Abstand zwischen dem ersten Bereich und dem zweiten Bereich des Taktes D wird konstant gewählt. Auch der zeitliche Abstand des Beginns des ersten Bereichs des Taktes T zum Beginn des Taktes D ist konstant. Die zeitlichen Bereiche des Taktes D sowie deren Lage in der Hell- bzw. Dunkelphase können prinzipiell beliebig gewählt werden. Bevorzugt wird jedoch die Lage und Breite des ersten Bereiches des Taktes D so gewählt, daß die Intensität des emittierten Lichts in der Hellphase eines Taktes während des letzten Lichtpulses gemessen wird. Die Lage des zweiten Bereichs des Taktes D wird so gelegt, daß die Intensität des emittierten Lichtes in der Dunkelphase nach einer konstanten Zeitspanne nach dem letzten Lichtspuls gemessen wird. Die konstante Zeitspanne wird so gewählt, daß die Detektion der Intensität des emittierten Lichts in der Dunkelphase noch innerhalb des kürzestmöglichen Taktes T erfolgt. The clock D controls the time of detection of the emitted light the sensor 30. This clock D contains two areas with a logical 1. The only the area controls the detection of the emitted light in the area of the bright phase and the second area controls the detection in the dark phase area. The time interval between the first area and the second The range of clock D is chosen to be constant. The time interval of the The beginning of the first area of the clock T at the beginning of the clock D is constant. The time ranges of clock D and their position in the bright or dark phase can in principle be chosen arbitrarily. Prefers however, the position and width of the first area of the clock D is chosen so that the intensity of the emitted light in the bright phase of a clock is measured during the last light pulse. The location of the second area the clock D is placed so that the intensity of the emitted light in the dark phase after a constant period after the last one Light pulse is measured. The constant time period is chosen so that the detection of the intensity of the emitted light in the dark phase takes place within the shortest possible cycle T.

Da der Takt T, wie oben beschrieben, von der Transportgeschwindigkeit V des Blattguts abhängt, variiert dieser mit einer Variation der Transportgeschwindigkeit V. Da das oben beschriebene Verfahren zur Detektion der Intensität des emittierten Lichts in der Hell- bzw. Dunkelphase lediglich vom Beginn des Taktes T abhängt, kann eine Verlangsamung des Taktes T, d.h. eine Verlangsamung der Transportgeschwindigkeit V, in gewissen Grenzen toleriert werden. Da die Detektion des emittierten Lichts in der Dunkelphase nach einer konstanten Zeitspanne nach dem letzten Lichtimpuls gemessen wird, ist auch die Reproduzierbarkeit der Intensität des emittierten Lichts in der Dunkelphase trotz der exponentiellen Abfalls der Intensität des phosphoreszent emittierten Lichts gewährleistet.Since the clock T, as described above, from the transport speed V depends on the sheet material, this varies with a variation of the transport speed V. Since the method described above for detecting the intensity of the emitted light in the light or dark phase only from Depends on the beginning of the clock T, a slowdown of the clock T, i.e. a slowing down of the transport speed V, within certain limits be tolerated. Because the detection of the emitted light in the dark phase measured after a constant period of time after the last light pulse is, the reproducibility of the intensity of the emitted light is also in the dark phase despite the exponential drop in the intensity of the phosphorescent emitted light guaranteed.

Aus den in der Hellphase und in der Dunkelphase des getakteten Anregungslichtes detektierten Intensitäten wird jeweils eine Intensität des fluoreszent emittierten Lichtes und eine Intensität des phosphoreszent emittierten Lichtes abgeleitet. Hierbei kann beispielsweise die Intensität des phosphoreszent emittierten Lichtes der Intensität in der Dunkelphase entsprechen. Die Intensität des fluoreszent emittierten Lichtes kann als Differenz der Intensität in der Hellphase und der Intensität in der Dunkelphase abgeleitet werden. Selbstverständlich ist es dem Fachmann möglich, an dieser Stelle auch andere arithmetische Operationen zur Ableitung der Intensität des fluoreszent bzw. phosphoreszent emittierten Lichts zu verwenden.From the in the light phase and in the dark phase of the clocked excitation light Detected intensities are fluorescence intensities emitted light and an intensity of the phosphorescent emitted Light derived. Here, for example, the intensity of the phosphorescent emitted light correspond to the intensity in the dark phase. The intensity of the fluorescent light emitted can be the difference of the Intensity in the light phase and intensity in the dark phase are derived become. Of course, it is possible for the expert at this point other arithmetic operations to derive the intensity of the to use fluorescent or phosphorescent emitted light.

Unter Verwendung des zweiten Sensors 40 kann das vom Blattgut emittierte Licht in mehreren unterschiedlichen Wellenlängenbereichen detektiert werden. Hierzu wird im Sensor 40 in der optischen Achse 44 ein Filter 42 vorgesehen, der lediglich einen Teilbereich des Wellenlängenbereichs des fluoreszent und phosphoreszent emittierten Lichts transmittiert. Da die Sensoren 30, 40 symmetrisch zum Maximum der Intensität der Beleuchtungseinrichtung 20 angeordnet sind, detektiert der Sensor 40 die Intensität des emittierten Lichtes in Transportrichtung am Anfang des beleuchteten Bereichs, bevorzugt vor dem Maximum der Intensität des Anregungslichts. Hieraus folgt, daß lediglich eine vernachlässigbar kleine Vorbeleuchtung des phosphoreszenten Stoffes bei der Detektion des emittierten Lichts durch den Sensor 40 stattgefunden hat. Das von dem Sensor 40 in der Dunkelphase detektierte emittierte Licht kann somit im wesentlichen nur unerwünschtes Streulicht sein, so daß die Intensität des in der Dunkelphase detektierten Lichts des Sensors 40 beispielsweise zur Normierung aller anderen gemessenen Intensitäten genutzt werden kann. Das vom Sensor 40 während der Hellphase detektierte emittierte Licht enthält somit fluoreszent emittiertes Licht, das durch den Filter 42 auf einen bestimmten Wellenlängenbereich eingeschränkt wird.Using the second sensor 40, that emitted by the sheet material can be Light can be detected in several different wavelength ranges. For this purpose, a filter 42 is provided in the sensor 40 in the optical axis 44. which is only a sub-range of the wavelength range of the fluorescent and emitted phosphorescent light. Because the sensors 30, 40 symmetrical to the maximum of the intensity of the lighting device 20 are arranged, the sensor 40 detects the intensity of the emitted Light in the transport direction at the beginning of the illuminated area, preferred before the maximum of the intensity of the excitation light. From this follows that only a negligibly small pre-illumination of the phosphorescent Substance in the detection of the emitted light by the sensor 40 has taken place. That detected by the sensor 40 in the dark phase emitted light can essentially only unwanted stray light be so that the intensity of the light detected in the dark phase of sensor 40, for example for normalizing all other measured Intensities can be used. That from sensor 40 during the light phase Detected emitted light thus contains fluorescent light that restricted to a certain wavelength range by the filter 42 becomes.

Während der Hellphase des Anregungslichts lassen sich somit vom Sensor 30 eine Gesamtintensität des fluoreszent emittierten Lichts und vom Sensor 40 eine Intensität eines bestimmten Wellenbereichs des fluoreszent emittierten Lichts ableiten. Beispielsweise durch Differenzbildung der detektierten Gesamtintensität des Sensors 30 und der detektierten Intensität des Sensors 40 läßt sich auch eine Intensität des fluoreszent emittierten Lichts in dem zum Wellenlängenbereich des Sensors 40 komplementären Wellenlängenbereich ableiten.During the bright phase of the excitation light, the sensor can 30 an overall intensity of the fluorescent light emitted and from the sensor 40 an intensity of a specific waveband of the fluorescent emitted Derive light. For example, by forming the difference between the detected Total intensity of the sensor 30 and the detected intensity of the sensor 40 can also be an intensity of the fluorescent light emitted in the to the wavelength range of the sensor 40 complementary wavelength range derived.

Während der Dunkelphase detektiert der Sensor 30 die Intensität des phosphoreszent emittierten Lichts. Über den Takt T lassen sich die abgeleiteten Intensitäten einem Ort mit der gewünschten Auflösung A auf der Banknote 50 zuordnen. During the dark phase, the sensor 30 detects the intensity of the phosphorescent emitted light. The derived ones can be derived from clock T Intensities a place with the desired resolution A on the banknote 50 assign.

Als Ergebnis des Verfahrens erhält man, wie in Fig. 3a dargestellt, für jeden Sensor 30, 40 entlang jeder Spur über die gesamte Länge des Blattguts einen nach Wellenlängenbereichen aufgelösten Intensitätsverlauf des emittierten Lichts. Hierbei wird durch den Sensor 30 in der Hellphase der Intensitätsverlauf IF detektiert, der den gesamten Wellenlängenbereich des emittierten Lichts enthält. Vom Sensor 40 wird in der Hellphase der Intensitätsverlauf IR detektiert, der hier beispielsweise lediglich den roten Wellenlängenbereich des emittierten Lichts enthält. Der Intensitätsverlauf IG des gelbgrün emittierten Lichts ergibt sich als Differenz des Intensitätsverlaufs IF und dem Intensitätsverlauf IR. Weiterhin erhält man einen Intensitätsverlauf IP für das in der Dunkelphase emittierte Licht, der in Fig. 3b dargestellt ist. Aus den Intensitätsverläufen werden dann, wie oben ausgeführt, die Intensitäten für phosphoreszentes Licht und fluoreszentes Licht in verschiedenen Wellenlängenbereichen abgeleitet.As a result of the method, as shown in FIG. 3a, for each sensor 30, 40 along each track over the entire length of the sheet material, an intensity curve of the emitted light is broken down according to wavelength ranges. Here, the intensity profile I F is detected by the sensor 30 in the light phase, which contains the entire wavelength range of the emitted light. In the bright phase, the sensor 40 detects the intensity curve I R , which here, for example, only contains the red wavelength range of the emitted light. The intensity curve I G of the yellow-green emitted light is the difference between the intensity curve I F and the intensity curve I R. Furthermore, an intensity curve I P is obtained for the light emitted in the dark phase, which is shown in FIG. 3b. As explained above, the intensities for phosphorescent light and fluorescent light in different wavelength ranges are then derived from the intensity profiles.

Wie oben beschrieben, kann durch eine geeignete Wahl der Spuren das vom gesamten Blattgut fluoreszent und phosphoreszent emittierte Licht mit einer gewünschten Auflösung detektiert werden.As described above, by a suitable choice of the tracks, that of the entire sheet material fluorescent and phosphorescent emitted light with a desired resolution can be detected.

Claims (26)

  1. An apparatus for detecting fluorescently and phosphorescently emitted light from sheet material such as papers of value or bank notes, comprising:
    an illuminating device for illuminating the sheet material with clocked excitation light,
    at least one sensor for detecting light emitted by the sheet material, and
    a transport system for transporting the sheet material past the illuminating device and sensor in a transport direction, whereby
    the sensor detects an intensity of emitted light in the light phase of the clocked excitation light and an intensity in the dark phase thereof,
    an evaluation device is provided for deriving an intensity of fluorescently emitted light and an intensity of phosphorescently emitted light from the intensities detected in the light phase and the dark phase of the clocked excitation light,
    the area of the sheet material illuminated by the illuminating device is a multiple of a desired resolution, and
    the sensor detects the intensity of emitted light within, and toward the end (in the transport direction) of, the area of the sheet material illuminated by the illuminating device.
  2. An apparatus according to claim 1, characterized in that the illuminating device has as an excitation lamp a gas discharge lamp emitting at least UV light.
  3. An apparatus according to claim 1, characterized in that the illuminating device has as an excitation lamp a fluorescent lamp.
  4. An apparatus according to claim 1, characterized in that the illuminating device has as an excitation lamp a gas discharge lamp without fluorescent substance.
  5. An apparatus according to claim 1, characterized in that the illuminating device has as an excitation lamp a gas discharge lamp emitting excitation light due to a reaction of excited noble gases with halogens.
  6. An apparatus according to claim 1, characterized in that the illuminating device has an excitation lamp located in a lightproof housing with a window with at least one filter which does not transmit the wave range of fluorescently and phosphorescently emitted light to be detected.
  7. An apparatus according to claim 6, characterized in that the filters are disposed at a fixed angle to a perpendicular to the transport direction.
  8. An apparatus according to claim 1, characterized in that the sensor has a detector array for detecting the intensity of emitted light.
  9. An apparatus according to claim 8, characterized in that the sensor has an optical system for imaging an area of the sheet material smaller than a desired resolution onto a detector of the detector array.
  10. An apparatus according to claim 9, characterized in that the optical system has at least one imaging unit of photoconductive material.
  11. An apparatus according to claim 8, characterized in that the sensor has at least one filter which transmits only the wave range of fluorescently and phosphorescently emitted light.
  12. An apparatus according to any of the above claims, characterized in that the optical axis of the sensor is disposed at a certain angle to the transport direction of the sheet material.
  13. An apparatus according to any of the above claims, characterized in that at least one second sensor is provided for detecting an intensity of emitted light in the light phase of clocked excitation light and an intensity in the dark phase thereof.
  14. An apparatus according to claim 13, characterized in that the second sensors are constructed analogously to the first sensor.
  15. An apparatus according to claim 13 or 14, characterized in that the first sensor detects the intensity of emitted light within, and toward the end (in the transport direction) of, the area of the sheet material illuminated by the illuminating de-device, and the second sensor the intensity of emitted light within, and toward the beginning (in the transport direction) of, the area illuminated by the illuminating device.
  16. An apparatus according to any of claims 13 to 15, characterized in that the sensors are disposed symmetrically to the illuminating device.
  17. An apparatus according to any of claims 13 to 16, characterized in that the first sensor has at least one filter which transmits only the wave range of fluorescently and phosphorescently emitted light, and the second sensor has at least one filter which transmits only a subrange of the wave range of fluorescently and phosphorescently emitted light.
  18. An apparatus according to any of the above claims, characterized in that the illuminating device and the sensors are located in a lightproof housing with a transparent window which transmits both the wave range of excitation light and the wave range of fluorescently and phosphorescently emitted light.
  19. An apparatus according to claim 18, characterized in that the transparent window is dereflected at least for light at a certain angle.
  20. A method for detecting fluorescently and phosphorescently emitted light from sheet material such as papers of value or bank notes, comprising the following steps:
    illuminating the sheet material with clocked excitation light,
    detecting the light emitted by the sheet material, and
    transporting the sheet material in a transport direction through the excitation light and the detection area of the light emitted by the sheet material, whereby
    an intensity of emitted light is detected in the light phase of clocked excitation light and an intensity of emitted light in the dark phase thereof, and
    an intensity of fluorescently emitted light and an intensity of phosphorescently emitted light are derived from the intensities detected in the light phase and the dark phase of clocked excitation light,
    characterized in that the intensity of fluorescently emitted light is derived as the difference of intensity in the light phase and intensity in the dark phase, and the intensity of phosphorescently emitted light corresponds to the intensity in the dark phase.
  21. A method according to claim 20, characterized in that the clock of excitation light is selected as the quotient of the transport speed of the sheet material and a desired resolution.
  22. A method according to claim 21, characterized in that the excitation light has a certain number of light pulses emitted at the beginning of the clock.
  23. A method according to claim 22, characterized in that the intensity is measured in the light phase of a clock during the last light pulse.
  24. A method according to claim 22, characterized in that the intensity is measured in the dark phase of a clock after a constant time period after the last light pulse.
  25. A method according to claim 20, characterized in that the detection area of light emitted by the sheet material is illuminated before detection over several clocks of excitation light by the latter.
  26. A method according to claim 20, characterized in that the light emitted by the sheet material is detected in several different wave ranges.
EP97954730A 1996-12-09 1997-12-09 Device and method for detecting fluorescent and phosphorescent light Expired - Lifetime EP0943087B1 (en)

Applications Claiming Priority (3)

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DE19651101A DE19651101A1 (en) 1996-12-09 1996-12-09 Device and method for the detection of fluorescent and phosphorescent light
DE19651101 1996-12-09
PCT/EP1997/006879 WO1998026276A1 (en) 1996-12-09 1997-12-09 Device and method for detecting fluorescent and phosphorescent light

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EP0943087A1 EP0943087A1 (en) 1999-09-22
EP0943087B1 true EP0943087B1 (en) 2003-08-13

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EP (1) EP0943087B1 (en)
JP (1) JP3790931B2 (en)
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CN1096608C (en) 2002-12-18
RU2170420C2 (en) 2001-07-10
WO1998026276A1 (en) 1998-06-18
EP0943087A1 (en) 1999-09-22
JP3790931B2 (en) 2006-06-28
CN1244920A (en) 2000-02-16
AU5984098A (en) 1998-07-03
JP2001506001A (en) 2001-05-08
US6297509B1 (en) 2001-10-02
DE59710585D1 (en) 2003-09-18
DE19651101A1 (en) 1998-06-10
ATE247280T1 (en) 2003-08-15
UA48284C2 (en) 2002-08-15

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