EP0088169A1 - System and apparatus to detect intaglio printing - Google Patents

System and apparatus to detect intaglio printing Download PDF

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Publication number
EP0088169A1
EP0088169A1 EP82201645A EP82201645A EP0088169A1 EP 0088169 A1 EP0088169 A1 EP 0088169A1 EP 82201645 A EP82201645 A EP 82201645A EP 82201645 A EP82201645 A EP 82201645A EP 0088169 A1 EP0088169 A1 EP 0088169A1
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EP
European Patent Office
Prior art keywords
disc
support
sectors
intaglio
transparent
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
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EP82201645A
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German (de)
French (fr)
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EP0088169B1 (en
Inventor
Daniel Gasser
Thomas Sidler
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Compagnie Industrielle Radioelectrique SA
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Compagnie Industrielle Radioelectrique SA
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Priority to AT82201645T priority Critical patent/ATE17971T1/en
Publication of EP0088169A1 publication Critical patent/EP0088169A1/en
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    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
    • G07D7/00—Testing 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
    • G07D7/06—Testing 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
    • G07D7/12—Visible light, infrared or ultraviolet radiation

Definitions

  • the present invention relates to a method and a device for the detection of a graphic print in intaglio, having a succession of lines, on a support, for example a bank note or fiduciary paper.
  • Intaglio printing differs from other printing methods, in particular offset printing, by a relief.
  • a mechanical probe is used which is integral with the movable core of a differential transformer, the primary winding of which is supplied by a generator delivering a carrier frequency, which is modulated by the movement of the core of the differential transformer if it moves due to the movement of the probe passing over a graphic printed in intaglio.
  • Signal demodulation therefore makes it possible to recognize the presence of an intaglio.
  • Such a detector makes it possible to detect height differences of the order of a micron, but such a device is expensive, delicate, sensitive to soiling due to the physical contact of the probe with the banknote, and its working speed is limited.
  • the present invention also aims to detect a print in intaglio, by its relief, on a support, in particular a bank note, without physical contact with it but by a process simpler to implement and having to satisfy less restrictive conditions.
  • the method according to the invention takes advantage of an optical effect.
  • a photo taken on a bank note lit by grazing light reveals periodic shadows highlighting the relief of places with an intaglio print.
  • a cache made up of black and transparent periodic lines spaced by a distance equal to the distance separating two lines of the graphic printed in intaglio we perceive a phenomenon of moiré due to the simultaneous passage of the shadow bands and clear bands in all the slots of the cover or, in other words, at the corresponding periodicity of the dark lines of the note and of the slots of the cover, periodicity which does not exist on imitations.
  • the same cover is moved in front of a counterfeit note, for example a photocopy, we do not notice this moiré effect, because there is no periodicity of dark and light bands or in all cases a periodicity does not appears only very briefly.
  • the method according to the invention therefore consists in illuminating the printed support with a light beam having an angle of incidence at least equal to 4 5 0 , in observing the support thus illuminated through a rotating disc having alternately transparent and opaque sectors spaced from each other by a distance at least approximately equal to the distance separating the lines of the graphics printed in intaglio, so as to recognize a moiré effect characteristic of the presence of an intaglio print.
  • the device for implementing the method comprises a light source illuminating the support at an incident angle of between 45 ° and 80 ° , a disc having alternately transparent and opaque sectors, a motor driving the rotating disc, a photoelectric sensor fixed, mounted near the disc on the side of the disc opposite said support and the sensitive surface of which covers several sectors of the disc, a lens placed between the illuminated support and the disc, forming an image of the illuminated part of the support on the sensor photoelectric and a circuit for detecting the periodic variation of the current delivered by the photoelectric sensor corresponding to the presence of an intaglio print.
  • the photoelectric sensor To perceive the moiré effect as the retina of the eye, the photoelectric sensor must receive the image of several lines of the printed graphics, that is to say extend over several transparent lines. Indeed, if the sensor were scanned by only one transparent line at a time, it would deliver only an alternating current corresponding to alternation - black and transparent lines, alternation which also exists on imitations.
  • a collimated light source A visible or infrared illuminates the surface B of the ticket to be checked at an angle of incidence of 45 ° to 80 °.
  • the banknote B is observed through the crown of a rotating disc D having alternately black or opaque and transparent sectors or lines.
  • an image of the illuminated part of the bill is formed using a lens C in a plane E in which there is an optoelectronic detector F extending over several transparent lines of the disc D. The detector F then sees a light signal whose intensity varies with a frequency proportional to the speed of rotation of the disk D and to the number of transparent lines which it comprises.
  • the alternating signal is optimal if the sensitive surface of the detector F extends over a few entire transparent lines of the disc. It is therefore sufficient to transform this analog signal into a digital signal and to count a certain number of pulses to be sure that it is indeed a moiré effect due to an intaglio print and not a signal due the presence of another relief, for example a stain.
  • FIG. 2 A suitable device for implementing the method is shown diagrammatically in FIG. 2.
  • the banknote 20 to be checked is driven, in a manner known per se, on a rotary drum 21 in front of an objective 22 comprising a lens 19 with a focal distance of 40 mm forming an image with a magnification of 1.1 on a sensor 3 placed behind a rotating disc 2 driven by a motor 1.
  • the lens 22 further comprises two mirrors 23 deflecting the beam of 180 °.
  • the ticket 20 is illuminated by means of an infrared emitter 18 comprising a transmitting diode sending a collimated light beam on the ticket 20 at an incident angle of approximately 45 °.
  • Block 18 further includes a state detector which indicates whether the emitting diode is in operation. This information is given on two inverted outputs OUT 2 and OUT 3.
  • the DC motor 1 drives the disc 2 at a speed of about 2170 rpm.
  • This disc 2 has an outside diameter of 40 mm and a peripheral crown with a width of approximately 3 mm comprising 250 black lines and 250 alternating transparent lines, with the same width of approximately 0.5 mm.
  • the sensor 3 constituted by a photodiode the receiving surface of which covers a square 3 mm in side. This receiving surface covers a series of 7 to 8 lines. It turns out that it is advisable to take into account a series of at least 7 to 8 lines to bring out the moiré effect.
  • the alternation frequency of the black and transparent lines for a fixed point is 9.04 kHz.
  • the photodiode constituting the sensor 3, sensitive to this alternation, delivers a current varying at this same frequency.
  • the moiré effect results in a regular and well-marked variation of the current, that is to say by an alternating current of relatively large amplitude and a frequency of 9.04 kHz. It is clear, however, that a change in the speed of the motor or in the number of lines of the disc has the effect of modifying the frequency of this current.
  • the alternating current delivered by the sensor 3 is transformed into an alternating voltage modulated by means of a current-voltage converter 4.
  • the alternating voltage is filtered through a bandpass filter 6 whose cut-off frequencies are 8.5 respectively kHz and 11.8 kHz, then amplified by means of an adjustable gain amplifier 7 which delivers a signal of the order of a volt which can be processed using a trigger 8 with adjustable trigger level .
  • the amplitude of the alternating voltage illustrating the intaglio is 2 to 6 times greater than that of a signal from a ticket without intaglio, this depending on the density of the intaglio of the ticket and of the position of taking information on it.
  • Trigger 8 works between -15V and +15 V.
  • the pulses delivered by the trigger 8, corresponding to the repetition of the moiré zones, are applied to an interface circuit 9 which converts them into pulses between 0 and +15 V in order to be able to attack a counter 10 consisting of a cascading of two Johnson decades, thus counting up to 100 pulses.
  • a manual selector 13 makes it possible to choose the minimum number of pulses that the counter 10 must count so that a selection logic 14 delivers a signal in the form of a pulse on its output OUT 1 signifying that the controlled ticket has a graphic intaglio, that is to say it is authentic.
  • the rotary drum 21 is also associated with an angular sensor delivering an impulse to a shaping circuit 12 which generates an adjustable validation or reading window and covering part of the ticket, that is to say determining the time during which we will read the information carried by the ticket.
  • This validation window is sent to the selection logic 14. In the absence of the validation window, the counter 10 is at zero.
  • a double switch 5 makes it possible to deactivate the detection circuit while indicating its state to the detection logic 14, as illustrated by the position of the two contacts of this switch 5 in the drawing. In this position, the lower contact, in the drawing, of the switch 5 leaves the validation window on the output OUT 1 of the selection logic 14, if the detector is not engaged.
  • the blocks 11, 15 and 17 are simply inverters. Block 16 represents the power supplies for the circuit and the motor.

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Toxicology (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Inspection Of Paper Currency And Valuable Securities (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

Le procédé consiste à observer, de préférence au moyen d'un capteur optoélectronique (F), le support à contrôler (B) éclairé avec un faisceau lumineux présentant un angle d'incidence au moins égal à 45°, à travers un disque tournant (D) présentant des secteurs alternativement transparents et opaques espacés les uns des autres d'une distance au moins approximativement égale à la distance séparant les lignes du graphisme imprimé en taille-douce sur un support (B). L'image du support est formée dans le plan (E) du détecteur (F) au moyen d'une optique (C). Si le support présente une impression en taille-douce, on peut observer un effet de moiré. Si le capteur (F) s'étend sur plusieurs secteurs transparents du disque (D), cet effet de moiré se traduit électriquement par une variation périodique très marquée du courant délivré par le capteur, à la fréquence de défilement des secteurs.The method consists in observing, preferably by means of an optoelectronic sensor (F), the support to be checked (B) illuminated with a light beam having an angle of incidence at least equal to 45 °, through a rotating disc ( D) having alternately transparent and opaque sectors spaced from each other by a distance at least approximately equal to the distance separating the lines of the graphics printed in intaglio on a support (B). The image of the support is formed in the plane (E) of the detector (F) by means of an optic (C). If the support has an intaglio print, we can observe a moiré effect. If the sensor (F) extends over several transparent sectors of the disc (D), this moiré effect is electrically manifested by a very marked periodic variation in the current delivered by the sensor, at the frequency of travel of the sectors.

Description

La présente invention a pour objet un procédé et un dispositif pour la détection d'une impression graphique en taille douce, présentant une succession de lignes, sur un support, par exemple un billet de banque ou papier fiduciaire.The present invention relates to a method and a device for the detection of a graphic print in intaglio, having a succession of lines, on a support, for example a bank note or fiduciary paper.

L'impression en taille douce se distingue des autres modes d'impressions, notamment de l'impression offset, par un relief. En pratique, seuls les billets de banque authentiques présentent un graphisme imprimé en taille douce. On a dès lors déjà proposé de contrôler l'authenticité des billets de banque par la détection de cette taille douce. A cet effet, on utilise un palpeur mécanique solidaire du noyau mobile d'un transformateur différentiel dont l'enroulement primaire est alimenté par un générateur délivrant une fréquence porteuse, laquelle est modulée par le mouvement du noyau du transformateur différentiel si celui-ci se déplace en raison du mouvement du palpeur passant sur un graphisme imprimé en taille douce. La démodulation du signal permet dès lors de reconnaître la présence d'une taille douce. Un tel détecteur permet de détecter des différences de hauteur de l'ordre du micron, mais un tel dispositif est coûteux, délicat, sensible aux salissures en raison du contact physique du palpeur avec le billet, et sa vitesse de travail est limitée.Intaglio printing differs from other printing methods, in particular offset printing, by a relief. In practice, only authentic banknotes have a graphic printed in intaglio. It has therefore already been proposed to check the authenticity of banknotes by detecting this intaglio. For this purpose, a mechanical probe is used which is integral with the movable core of a differential transformer, the primary winding of which is supplied by a generator delivering a carrier frequency, which is modulated by the movement of the core of the differential transformer if it moves due to the movement of the probe passing over a graphic printed in intaglio. Signal demodulation therefore makes it possible to recognize the presence of an intaglio. Such a detector makes it possible to detect height differences of the order of a micron, but such a device is expensive, delicate, sensitive to soiling due to the physical contact of the probe with the banknote, and its working speed is limited.

Il a été proposé de détecter une impression en taille douce constituée de lignes parallèles, telle qu'on la rencontre sur des billets de banque par son relief, par des moyens optiques, c'est-à-dire sans contact physique (US-A-3.634.012). Ce procédé consiste à éclairer alternativement les lignes imprimées par deux faisceaux de lumière rasante identiques, d'une part selon une direction transversale aux lignes et d'autre part selon une direction parallèle à ces lignes et de comparer la quantité de lumière reçue respectivement par deux cellules, la quantité de lumière réfléchie transversalement aux lignes étant inférieure à la quantité de lumière réfléchie parallèlement aux lignes, dans le cas d'une impression en taille douce, en raison de l'ombre formée par le relief. La mise en oeuvre de ce procédé est toutefois relativement compliquée et délicate. Elle nécessite des moyens mécaniques pour assurer l'alternance des faisceaux, plusieurs miroirs et des écrans. La surface de test doit être absolument plane et l'espace environnant doit être exempt de réflexions. Les faisceaux lumineux sont envoyés dans un tunnel. L'angle d'incidence des faisceaux doit être élevé.It has been proposed to detect an intaglio print consisting of parallel lines, such as is encountered on banknotes by its relief, by optical means, that is to say without physical contact (US-A -3.634.012). This process consists in alternately illuminating the lines printed by two identical beams of grazing light, on the one hand in a direction transverse to the lines and on the other hand in a direction parallel to these lines and to compare the amount of light received respectively by two cells, the amount of light reflected transversely to the lines being less than the amount of light reflected parallel to the lines, in the case of intaglio printing, due to the shadow formed by the relief. The implementation of this process is however relatively complicated and delicate. It requires mechanical means to ensure the alternation of beams, several mirrors and screens. The test surface must be absolutely flat and the surrounding space must be free of reflections. The light beams are sent through a tunnel. The angle of incidence of the beams must be high.

La présente invention a également pour but de détecter une impression en taille douce, par son relief, sur un support, en particulier un billet de banque, sans contact physique avec celui-ci mais par un procédé plus simple à mettre en oeuvre et devant satisfaire des conditions moins contraignantes.The present invention also aims to detect a print in intaglio, by its relief, on a support, in particular a bank note, without physical contact with it but by a process simpler to implement and having to satisfy less restrictive conditions.

Le procédé selon l'invention tire parti d'un effet optique. Une photo prise sur un billet de banque éclairé par une lumière rasante fait apparaître des zones d'ombre périodiques faisant ressortir le relief des endroits présentant une impression en taille douce. En déplaçant devant la photo un cache composé de raies périodiques noires et transparentes espacées d'une distance égale à la distance séparant deux lignes du graphisme imprimées en taille douce, on perçoit un phénomène de moiré dû au passage simultané des bandes d'ombre et des bandes claires dans toutes les fentes du cache ou, autrement dit, à la périodicité correspondante des raies sombres du billet et des fentes du cache, périodicité qui n'existe pas sur des imitations. Si par contre on déplace le même cache devant un faux billet, par exemple une photocopie, on ne constate pas cet effet de moiré, car il n'y a pas de périodicité de bandes sombres et claires ou dans tous les cas une périodicité n'apparaît que très brièvement.The method according to the invention takes advantage of an optical effect. A photo taken on a bank note lit by grazing light reveals periodic shadows highlighting the relief of places with an intaglio print. By moving in front of the photo a cache made up of black and transparent periodic lines spaced by a distance equal to the distance separating two lines of the graphic printed in intaglio, we perceive a phenomenon of moiré due to the simultaneous passage of the shadow bands and clear bands in all the slots of the cover or, in other words, at the corresponding periodicity of the dark lines of the note and of the slots of the cover, periodicity which does not exist on imitations. If, on the other hand, the same cover is moved in front of a counterfeit note, for example a photocopy, we do not notice this moiré effect, because there is no periodicity of dark and light bands or in all cases a periodicity does not appears only very briefly.

Le procédé selon l'invention consiste dès lors à éclairer le support imprimé avec un faisceau lumineux présentant un angle d'incidence au moins égal à 45 0, à observer le support ainsi éclairé à travers un disque tournant présentant des secteurs alternativement transparents et opaques espacés les uns des autres d'une distance au moins approximativement égale à la distance séparant les lignes du graphisme imprimées en taille douce, de manière à reconnaître un effet de moiré caractéristique de la présence d'une impression en taille douce.The method according to the invention therefore consists in illuminating the printed support with a light beam having an angle of incidence at least equal to 4 5 0 , in observing the support thus illuminated through a rotating disc having alternately transparent and opaque sectors spaced from each other by a distance at least approximately equal to the distance separating the lines of the graphics printed in intaglio, so as to recognize a moiré effect characteristic of the presence of an intaglio print.

En pratique, l'observation est faite par voie optoélectronique de manière à détecter un battement électrique correspondant à l'effet de moiré caractéristique de la présence d'une impression en taille douce. Ce battement se distingue nettement de la variation irrégulière observée sur un faux billet.In practice, the observation is made optoelectronically so as to detect an electric beat corresponding to the moiré effect characteristic of the presence of an intaglio print. This beat is clearly distinguished from the irregular variation observed on a counterfeit note.

Le dispositif pour la mise en oeuvre du procédé comprend une source de lumière éclairant le support sous un angle incident compris entre 45° et 800, un disque présentant des secteurs alternativement transparents et opaques, un moteur entraînant le disque en rotation, un capteur photoélectrique fixe, monté à proximité du disque du côté de celui-ci opposé audit support et dont la surface sensible recouvre plusieurs secteurs du disque, un objectif placé entre le support éclairé et le disque, formant une image de la partie éclairée du support sur le capteur photoélectrique et un circuit de détection de la variation périodique du courant délivré par le capteur photoélectrique correspondant à la présence d'une impression en taille douce.The device for implementing the method comprises a light source illuminating the support at an incident angle of between 45 ° and 80 ° , a disc having alternately transparent and opaque sectors, a motor driving the rotating disc, a photoelectric sensor fixed, mounted near the disc on the side of the disc opposite said support and the sensitive surface of which covers several sectors of the disc, a lens placed between the illuminated support and the disc, forming an image of the illuminated part of the support on the sensor photoelectric and a circuit for detecting the periodic variation of the current delivered by the photoelectric sensor corresponding to the presence of an intaglio print.

Pour percevoir l'effet de moiré comme la rétine de l'oeil, le capteur photoélectrique doit recevoir l'image de plusieurs lignes du graphisme imprimé, c'est-à-dire s'étendre sur plusieurs raies transparentes. En effet, si le capteur n'était balayé que par une seule raie transparente à la fois, il ne délivrerait qu'un courant alternatif correspondant à alternance-des raies noires et transparentes, alternance qui existe également sur des imitations.To perceive the moiré effect as the retina of the eye, the photoelectric sensor must receive the image of several lines of the printed graphics, that is to say extend over several transparent lines. Indeed, if the sensor were scanned by only one transparent line at a time, it would deliver only an alternating current corresponding to alternation - black and transparent lines, alternation which also exists on imitations.

Le dessin représente, à titre d'exemple, un mode de mise en oeuvre du procédé selon l'invention.

  • La figure 1 illustre schématiquement le principe du procédé utilisé.
  • La figure 2 est un schéma bloc du dispositif de détection.
The drawing represents, by way of example, an embodiment of the method according to the invention.
  • Figure 1 schematically illustrates the principle of the method used.
  • Figure 2 is a block diagram of the detection device.

Selon la figure 1 une source de lumière collimatée A, visible ou infrarouge, éclaire la surface B du billet à contrôler sous un angle d'incidence de 45° à 80°. Le billet B est observé à travers la couronne d'un disque tournant D présentant des secteurs ou raies alternativement noirs ou opaques et transparents. Pour l'observation optoélectronique on forme à l'aide d'une lentille C une image de la partie éclairée du billet dans un plan E dans lequel se trouve un détecteur optoélectronique F s'étendant sur plusieurs raies transparentes du disque D. Le détecteur F voit alors un signal lumineux dont l'intensité varie avec une fréquence proportionnelle à la vitesse de rotation du disque D et au nombre de raies transparentes que comporte celui-ci. Le signal alternatif est optimal si la surface sensible du détecteur F s'étend sur quelques raies transparentes entières du disque. Il suffit dès lors de transformer ce signal analogique en un signal numérique et de compter un certain nombres d'impulsions pour être sûr qu'il s'agit bien d'un effet de moiré dû à une impression en taille douce et non un signal dû à la présence d'un autre relief par exemple une salissure.According to FIG. 1, a collimated light source A, visible or infrared, illuminates the surface B of the ticket to be checked at an angle of incidence of 45 ° to 80 °. The banknote B is observed through the crown of a rotating disc D having alternately black or opaque and transparent sectors or lines. For optoelectronic observation, an image of the illuminated part of the bill is formed using a lens C in a plane E in which there is an optoelectronic detector F extending over several transparent lines of the disc D. The detector F then sees a light signal whose intensity varies with a frequency proportional to the speed of rotation of the disk D and to the number of transparent lines which it comprises. The alternating signal is optimal if the sensitive surface of the detector F extends over a few entire transparent lines of the disc. It is therefore sufficient to transform this analog signal into a digital signal and to count a certain number of pulses to be sure that it is indeed a moiré effect due to an intaglio print and not a signal due the presence of another relief, for example a stain.

Un dispositif approprié pour la mise en oeuvre du procédé est représenté schématiquement à la figure 2. Le billet 20 à contrôler est entraîné, de manière connu en soi, sur un tambour rotatif 21 devant un objectif 22 comportant une lentille 19 d'une distance focale de 40 mm formant une image avec un agrandissement de 1,1 sur un capteur 3 placé derrière un disque rotatif 2 entraîné par un moteur 1. Pour des questions de réduction géométrique, l'objectif 22 comporte en outre deux miroirs 23 déviant le faisceau de 180°. Le billet 20 est éclairé au moyen d'un émetteur infrarouge 18 comportant une diode émettrice envoyant un faisceau lumineux collimaté sur le billet 20 sous un angle incident d'environ 45°. Le bloc 18 comporte en outre un détecteur d'état qui indique si la diode émettrice est bien en fonctionnement. Ces informations sont données sur deux sorties inversées OUT 2 et OUT 3.A suitable device for implementing the method is shown diagrammatically in FIG. 2. The banknote 20 to be checked is driven, in a manner known per se, on a rotary drum 21 in front of an objective 22 comprising a lens 19 with a focal distance of 40 mm forming an image with a magnification of 1.1 on a sensor 3 placed behind a rotating disc 2 driven by a motor 1. For reasons of geometric reduction, the lens 22 further comprises two mirrors 23 deflecting the beam of 180 °. The ticket 20 is illuminated by means of an infrared emitter 18 comprising a transmitting diode sending a collimated light beam on the ticket 20 at an incident angle of approximately 45 °. Block 18 further includes a state detector which indicates whether the emitting diode is in operation. This information is given on two inverted outputs OUT 2 and OUT 3.

Le moteur à courant continu 1 entraîne le disque 2 à une vitesse d'environ 2170 tours/min. Ce disque 2 présente un diamètre extérieur de 40 mm et une couronne périphérique d'une largeur d'environ 3 mm comportant 250 raies noires et 250 raies transparentes alternées, d'une même largeur d'environ 0,5 mm. Immédiatement derrière le disque est placé le capteur 3 constitué par une photodiode dont la surface réceptrice couvre un carré de 3 mm de côté. Cette surface réceptrice recouvre une suite de 7 à 8 raies. Il s'avère en effet qu'il convient de tenir compte d'une suite d'au moins 7 à 8 raies pour bien ressortir l'effet de moiré. La fréquence d'alternance des raies noires et transparentes pour un point fixe est de 9,04 kHz. La photodiode constituant le capteur 3, sensible à cette alternance, délivre un courant variant à cette même fréquence. L'effet de moiré se traduit par une variation régulière et bien marquée du courant c'est-à-dire par un courant alternatif d'amplitude relativement grande et d'une fréquence de 9,04 kHz. Il est clair toutefois qu'un changement de la vitesse du moteur ou du nombre de raies du disque a pour effet de modifier la fréquence de ce courant.The DC motor 1 drives the disc 2 at a speed of about 2170 rpm. This disc 2 has an outside diameter of 40 mm and a peripheral crown with a width of approximately 3 mm comprising 250 black lines and 250 alternating transparent lines, with the same width of approximately 0.5 mm. Immediately behind the disc is placed the sensor 3 constituted by a photodiode the receiving surface of which covers a square 3 mm in side. This receiving surface covers a series of 7 to 8 lines. It turns out that it is advisable to take into account a series of at least 7 to 8 lines to bring out the moiré effect. The alternation frequency of the black and transparent lines for a fixed point is 9.04 kHz. The photodiode constituting the sensor 3, sensitive to this alternation, delivers a current varying at this same frequency. The moiré effect results in a regular and well-marked variation of the current, that is to say by an alternating current of relatively large amplitude and a frequency of 9.04 kHz. It is clear, however, that a change in the speed of the motor or in the number of lines of the disc has the effect of modifying the frequency of this current.

Le courant alternatif délivré par le capteur 3 est transformé en une tension alternative modulée au moyen d'un convertisseur courant-tension 4. La tension alternative est filtrée à travers un filtre passe-bande 6 dont les fréquences de coupure sont respectivement de 8,5 kHz et 11,8 kHz, puis amplifiée au moyen d'un amplificateur à gain réglable 7 qui délivre un signal de l'ordre du volt qu'il est possible de traiter à l'aide d'un trigger 8 à niveau de déclenchement ajustable. L'amplitude de la tension alternative illustrant la taille douce est de 2 à 6 fois plus grande que celle d'un signal issu d'un billet sans taille douce, ceci dépendant de la densité de la taille douce du billet et de la position de la prise de l'information sur celui-ci.The alternating current delivered by the sensor 3 is transformed into an alternating voltage modulated by means of a current-voltage converter 4. The alternating voltage is filtered through a bandpass filter 6 whose cut-off frequencies are 8.5 respectively kHz and 11.8 kHz, then amplified by means of an adjustable gain amplifier 7 which delivers a signal of the order of a volt which can be processed using a trigger 8 with adjustable trigger level . The amplitude of the alternating voltage illustrating the intaglio is 2 to 6 times greater than that of a signal from a ticket without intaglio, this depending on the density of the intaglio of the ticket and of the position of taking information on it.

Le trigger 8 travaille entre -15V et +15V. Les impulsions délivrées par le trigger 8, correspondant à la répétition des zones de moiré, sont appliquées à un circuit interface 9 qui les convertit en impulsions comprises entre 0 et +15V pour pouvoir attaquer un compteur 10 constitué d'une mise en cascade de deux décades Johnson, pouvant ainsi compter jusqu'à 100 impulsions. Un sélecteur manuel 13 permet de choisir le nombre minimal d'impulsions que le compteur 10 doit compter pour qu'une logique de sélection 14 délivre un signal sous la forme d'une impulsion sur sa sortie OUT 1 signifiant que le billet contrôlé présente un graphisme en taille douce, c'est-à-dire qu'il est authentique.Trigger 8 works between -15V and +15 V. The pulses delivered by the trigger 8, corresponding to the repetition of the moiré zones, are applied to an interface circuit 9 which converts them into pulses between 0 and +15 V in order to be able to attack a counter 10 consisting of a cascading of two Johnson decades, thus counting up to 100 pulses. A manual selector 13 makes it possible to choose the minimum number of pulses that the counter 10 must count so that a selection logic 14 delivers a signal in the form of a pulse on its output OUT 1 signifying that the controlled ticket has a graphic intaglio, that is to say it is authentic.

Le tambour rotatif 21 est en outre associé à un capteur angulaire délivrant une impulsion à un circuit de mise en forme 12 qui génère une fenêtre de validation ou de lecture réglable et couvrant une partie du billet, c'est-à-dire déterminant le temps pendant lequel on va lire l'information portée par le billet. Cette fenêtre de validation est envoyée à la logique de sélection 14. En l'absence de la fenêtre de validation, le compteur 10 est à zéro.The rotary drum 21 is also associated with an angular sensor delivering an impulse to a shaping circuit 12 which generates an adjustable validation or reading window and covering part of the ticket, that is to say determining the time during which we will read the information carried by the ticket. This validation window is sent to the selection logic 14. In the absence of the validation window, the counter 10 is at zero.

Un double interrupteur 5 permet de mettre hors fonctionnement le circuit de détection tout en indiquant son état à la logique de détection 14, comme illustré par la position des deux contacts de cet interrupteur 5 dans le dessin. Dans cette position, le contact inférieur, dans le dessin, de l'interrupteur 5 sort la fenêtre de validation sur la sortie OUT 1 de la logique de sélection 14, si le détecteur n'est pas enclenché. Les blocs 11, 15 et 17 sont simplement des inverseurs. Le bloc 16 représente les alimentations du circuit et du moteur.A double switch 5 makes it possible to deactivate the detection circuit while indicating its state to the detection logic 14, as illustrated by the position of the two contacts of this switch 5 in the drawing. In this position, the lower contact, in the drawing, of the switch 5 leaves the validation window on the output OUT 1 of the selection logic 14, if the detector is not engaged. The blocks 11, 15 and 17 are simply inverters. Block 16 represents the power supplies for the circuit and the motor.

Claims (8)

1. Procédé de détection d'impression graphique en taille douce, présentant une succession de lignes, sur un support, caractérisé en ce qu'on éclaire le support avec un faisceau lumineux présentant un angle d'incidence au moins égal à 45° et qu'on observe le support ainsi éclairé à travers un disque tournant présentant des secteurs alternativement transparents et opaques espacés les uns des autres d'une distance au moins approximativement égale à la distance séparant les lignes du graphisme imprimé en taille douce, de manière à reconnaître un effet de moiré caractéristique de la présence d'une impression en taille douce.1. A method of detecting intaglio graphic printing, having a succession of lines, on a support, characterized in that the support is illuminated with a light beam having an angle of incidence at least equal to 45 ° and that '' the support thus lit is observed through a rotating disc having alternately transparent and opaque sectors spaced from each other by a distance at least approximately equal to the distance separating the lines of the graphic printed in intaglio, so as to recognize a moire effect characteristic of the presence of an intaglio print. 2. Procédé selon la revendication 1, caractérisé en ce que l'observation est faite par voie optoélectronique de manière à détecter une oscillation de l'intensité lumineuse correspondant à l'effet de moiré caractéristique de la présence d'une impression à taille douce.2. Method according to claim 1, characterized in that the observation is made optoelectronically so as to detect an oscillation of the light intensity corresponding to the moiré effect characteristic of the presence of an intaglio print. 3. Dispositif pour la mise en oeuvre du procédé selon la revendication 2, caractérisé par le fait qu'il comprend une source de lumière (18) éclairant le support (20) sous un angle incident compris entre 45° et 800, un disque (2) présentant des secteurs alternativement transparents et opaques, un moteur entraînant le disque en rotation, un capteur photoélectrique (3) fixe, monté à proximité du disque du côté de celui-ci opposé audit support (20) et dont la surface sensible recouvre plusieurs secteurs du disque (2), un objectif (22) placé entre le support éclairé et le disque, formant une image de la partie éclairée du support sur le capteur photoélectrique (3), et un circuit de détection de la variation périodique du courant délivré par le capteur photoélectrique correspondant à la présence d'une impression en taille douce.3. Device for implementing the method according to claim 2, characterized in that it comprises a light source (18) illuminating the support (20) at an incident angle between 45 ° and 80 0 , a disc (2) having alternately transparent and opaque sectors, a motor driving the rotating disc, a fixed photoelectric sensor (3) mounted near the disc on the side thereof opposite said support (20) and whose sensitive surface covers several sectors of the disc (2), a lens (22) placed between the illuminated support and the disc, forming an image of the illuminated part of the support on the photoelectric sensor (3), and a circuit for detecting the periodic variation of the current delivered by the photoelectric sensor corresponding to the presence of an intaglio print. 4. Dispositif selon la revendication 3 pour l'identification d'un billet de banque ou analogue, caractérisé par le fait que le nombre de secteurs alternativement opaques et transparents du disque (2) et la vitesse de rotation du disque sont tels que la fréquence d'alternance des secteurs opaques et transparents, vue du capteur fixe (3), est d'environ 9 kHz et que le capteur photoélectrique (3) présente une surface sensible s'étendant sur six à huit secteurs du disque, de préférence exactement six ou huit secteurs.4. Device according to claim 3 for the identification of a banknote or the like, characterized in that the number of alternately opaque and transparent sectors of the disc (2) and the speed of rotation of the disc are such that the frequency alternation of the opaque and transparent sectors, seen from the fixed sensor (3), is approximately 9 kHz and that the photoelectric sensor (3) has a sensitive surface extending over six to eight sectors of the disc, preferably exactly six or eight sectors. 5. Dispositif selon la revendication 3 ou 4, caractérisé par le fait que le circuit de détection comprend un convertisseur courant-tension (4), un filtre passe-bande (6), un trigger (8) délivrant des impulsions correspondant à chaque variation périodique de la tension alternative délivrée par le convertisseur, un compteur d'impulsions (10) et un circuit de sélection (13) des impulsions comptées permettant d'obtenir un signal en fonction.d'un nombre minimum d'impulsions comptées.5. Device according to claim 3 or 4, characterized in that the detection circuit comprises a current-voltage converter (4), a bandpass filter (6), a trigger (8) delivering pulses corresponding to each variation period of the alternating voltage delivered by the converter, a pulse counter (10) and a selection circuit (13) of the counted pulses making it possible to obtain a signal as a function of a minimum number of counted pulses. 6. Dispositif selon les revendications 4 et 5, caractérisé par le fait que la source de lumière (18) est une source de lumière infrarouge munie d'un collimateur.6. Device according to claims 4 and 5, characterized in that the light source (18) is an infrared light source provided with a collimator. 7. Dispositif selon les revendications 4 et 5, caractérisé par le fait que les fréquences de coupure du filtre passe-bande 6 sont de 8,5 kHz et 11,8 kHz.7. Device according to claims 4 and 5, characterized in that the cut-off frequencies of the bandpass filter 6 are 8.5 kHz and 11.8 kHz. 8. Dispositif selon l'une des revendications 4 à 7, caractérisé par le fait qu'il comprend un tambour d'entraînement (21) des billets à contrôler, délivrant par sa rotation un signal utilisé pour engendrer une fenêtre de validation de la détection (12).8. Device according to one of claims 4 to 7, characterized in that it comprises a drive drum (21) of the tickets to be checked, delivering by its rotation a signal used to generate a window for validation of the detection (12).
EP82201645A 1982-03-08 1982-12-21 System and apparatus to detect intaglio printing Expired EP0088169B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT82201645T ATE17971T1 (en) 1982-03-08 1982-12-21 GRAVO PRESSURE DETECTION METHOD AND APPARATUS.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH1395/82 1982-03-08
CH139582A CH645464A5 (en) 1982-03-08 1982-03-08 METHOD FOR DETECTION OF A GRAPHIC PRINT IN SOFT SIZE AND DEVICE FOR CARRYING OUT SAID METHOD.

Publications (2)

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EP0088169A1 true EP0088169A1 (en) 1983-09-14
EP0088169B1 EP0088169B1 (en) 1986-02-12

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Application Number Title Priority Date Filing Date
EP82201645A Expired EP0088169B1 (en) 1982-03-08 1982-12-21 System and apparatus to detect intaglio printing

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US (1) US4594514A (en)
EP (1) EP0088169B1 (en)
JP (1) JPS58154088A (en)
AT (1) ATE17971T1 (en)
CH (1) CH645464A5 (en)
DE (1) DE3269113D1 (en)

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WO1994006102A1 (en) * 1992-08-27 1994-03-17 Thomas De La Rue & Company Limited Security document inspection
NL9401796A (en) * 1994-10-28 1996-06-03 Tno Document recognition apparatus

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US3564268A (en) * 1969-06-27 1971-02-16 Standard Change Makers Inc Document verifier using photovoltaic cell with light sensitive bars
US3634012A (en) * 1969-04-16 1972-01-11 Rudolf Mustert Method and apparatus for examining intaglio printing
US4056731A (en) * 1973-11-07 1977-11-01 Ardac/Usa Reticle protective structure and radiation sensitive validation apparatus

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DE2204284B2 (en) * 1972-01-29 1974-04-25 National Rejectors Inc. Gmbh, 2150 Buxtehude Device for photoelectric testing of sheet material, in particular documents or banknotes

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US3457421A (en) * 1966-02-24 1969-07-22 Transmarine Corp Radiation sensitive paper security validation apparatus
DE1911897A1 (en) * 1969-03-08 1970-09-17 Scheidt & Bachmann Gmbh Method and device for checking securities
US3634012A (en) * 1969-04-16 1972-01-11 Rudolf Mustert Method and apparatus for examining intaglio printing
US3564268A (en) * 1969-06-27 1971-02-16 Standard Change Makers Inc Document verifier using photovoltaic cell with light sensitive bars
US4056731A (en) * 1973-11-07 1977-11-01 Ardac/Usa Reticle protective structure and radiation sensitive validation apparatus

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Cited By (4)

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Publication number Priority date Publication date Assignee Title
WO1994006102A1 (en) * 1992-08-27 1994-03-17 Thomas De La Rue & Company Limited Security document inspection
GB2283607A (en) * 1992-08-27 1995-05-10 De La Rue Thomas & Co Ltd Security document inspection
GB2283607B (en) * 1992-08-27 1996-06-19 De La Rue Thomas & Co Ltd Security document inspection
NL9401796A (en) * 1994-10-28 1996-06-03 Tno Document recognition apparatus

Also Published As

Publication number Publication date
JPS58154088A (en) 1983-09-13
DE3269113D1 (en) 1986-03-27
CH645464A5 (en) 1984-09-28
US4594514A (en) 1986-06-10
EP0088169B1 (en) 1986-02-12
ATE17971T1 (en) 1986-02-15

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