EP2746049A1 - Method for monitoring intaglio printing and corresponding colour control patches - Google Patents

Abstract

The method involves inking of a copper-plate for engraving or printing purposes with an engraving ink copper-plate. The inked copper plate is wiped, and a substrate is printed in a printing direction (I) by the copper-plate utilized for engraving or printing purposes by high pressure printing. An evaluation is made if impression pressure applied during printing of the substrate is adequate or not. A set of measures is applied to printed control fields for evaluating if the load of ink applied during inking of the copper plate is adequate or not. Independent claims are also included for the following: (1) a checking range (2) an engraved plate (3) a digital origination file.

Description

TECHNICAL AREA

The present invention relates in particular to a method for controlling intaglio printing, as well as to a control range intended for intaglio printing, in particular for the printing of securities, in particular banknotes. The present invention also relates to the use as well as the application of such a control range for verifying the printability of a safety pattern to be printed in intaglio, as well as for the control and, the if necessary, the adjustment of the printing parameters of an intaglio printing press.

TECHNOLOGICAL BACKGROUND

The intaglio is a secular printing technique which consists of printing patterns in relief by means of an intaglio printing plate (which is designated in the context of the present invention by the expression "plate of intaglio print "). The intaglio printing plate is inked on its surface by means of one or more inks. The surplus of ink off the engravings is then wiped and pushed inside the engravings. The printing plate thus inked and wiped is applied against a printable substrate (eg fiduciary paper) in a press exerting a high printing pressure and pressing the substrate against the printing plate so that the ink of the engravings is transferred to the substrate. The result is a document with a printed pattern reflecting the engraved patterns with additional relief or embossing, in register with the printed pattern, which reflects the depth of the engravings and which is typically recognizable by touch.

Intaglio printing presses, as used for the production of securities, in particular banknotes, are for example described in Swiss Patent No. CH 477 293 A5 , European patent applications published under Nos. EP 0 091 709 A1 , EP 0 406 157 A1 , EP 0 415 881 A2 , EP 0 563 007 A1 , EP 0 873 866 A1 , EP 1 602 483 A1 , and international applications published under Nos. WO 01/54904 A1 , WO 03/047862 A1 , WO 2004/026580 A1 , WO 2005/118294 A1 , WO 2011/077348 A1 , WO 2011/077350 A1 , WO 2011/077351 A1 , all in the name of the present Applicant.

For a long time, intaglio printing plates were hand-engraved in a soft metal plate, for example copper, brass or other suitable metal or metal alloy. The tools used by the engraver typically consisted of chisels or punches whose end was sharpened and adapted to the desired dimensions of the patterns to be engraved, the latter motifs consisting essentially of lines and curves modulated in dimensions, depending on the action exerted by the engraver, to produce tonal variations reproducing the half-tones of the image to be engraved, for example a portrait.

More recently photo-lithographic techniques have been proposed to facilitate the transfer of images on intaglio printing plates, as well as computer-assisted engraving processes.

The intaglio printing technique is particularly used in the field of the printing of securities, in particular for the printing of bank notes, intaglio printing remaining one of the printing techniques more difficult to counterfeit.

In the context of the printing of securities, in particular the printing of banknotes, techniques have been developed to assist the engraver in his task, particularly with a view to reducing necessary etching time as well as the production time of the printing plates. The approach adopted until very recently was to produce a single original engraved (by hand or assisted by technical means of engraving) representing a single document to be printed, and to replicate this original as many times as necessary to produce a printing plate comprising several identical replicas of said original. According to this approach, the etching technique used essentially follows that of a burner, that is to say that each pattern is etched according to the line of the line or curve concerned, that is to say in a substantially vector (see, for example, the international application published under No. WO 97/48555 A1 ).

The present Applicant has proposed an innovative approach for the production of intaglio printing plates, an approach which is described in the international application published under No. WO 03/103962 A1 (which application is incorporated by reference as a whole in the context of this application). This method consists in generating a set of three-dimensional digital data consisting of pixels each representative of an elementary point to be etched in the surface of the plate, the etching being performed pixel by pixel on the basis of said three-dimensional digital data. According to this technique, a printing plate can be directly etched. Alternatively, a printing plate precursor (preferably a metal plate carrying a polymer layer) may be etched. In the latter case, it is the polymer layer which is etched and the precursor thus etched is then used to manufacture printing plates by galvanic replication. Etching is also advantageously performed by laser. This etching process, both direct and indirect, is implemented commercially by the Applicant under the CTiP® (Computer to Intaglio Plate®) designation and has become, so to speak, a standard in the security printing industry.

In contrast to the earlier approach of making a single engraved original representing a single document to be printed, a plate as a whole can be engraved in a single phase, without the tedious process of replicating an original. According to the technique described in International Application No. WO 03/103962 A1 , replication of the original on the plate is performed in a digital environment, this in particular to compensate for distortions of paper during intaglio printing, compensation that was simply impossible using the techniques previously used. Moreover, the technique described in International Application No. WO 03/103962 A1 allows the creation of patterns that extend from one bank note to another, without discontinuities, that is to say, patterns that extend to the edge of the bank note without interruption (as one can see it on the illustration of the Figure 1 discussed below).

A considerable advantage of the aforementioned technique lies in the fact that it is essentially independent of the complexity of the patterns to be etched, whereas the prior techniques depend on the level of complexity of the etchings to be made.

An evolution of the technique described in International Application No. WO 03/103962 A1 , for the direct etching of intaglio printing plates, is described in the international application published under No. WO 2009/138901 A1 (which application is also incorporated by reference as a whole in the context of this application).

These various computer-assisted techniques have enabled the development of a wide range of security features exploiting the advantageous properties of intaglio printing, including in particular dual-tone or multi -tone elements. (" multi-tone ") which exploit the tonal variations of the intaglio ink, continuous backgrounds, latent images ( latent Images "), micro-prints in positive or negative (" positive / negative micro-print "), tactile elements, etc. With these techniques, high complexity security elements, to effectively fight against counterfeiting, can be achieved. Illustrative examples are presented in particular in international applications published under Nos. WO 2005/090090 A1 and WO 2007/119203 A1 .

The Figure 1 shows for illustration a black and white reproduction of a specimen of bank note produced by the Claimant and distributed to the public on the occasion of the XIX ^th International Conference of Security Printers ( XIX ^th International Security Printers Conference ") Organized by Intergraf ( www.intergraf.eu ) and held during May 2003 in Montreux (Switzerland). This specimen, representing Lord Byron, was produced according to the aforementioned CTiP® process, all the elements visible on the Figure 1 consisting of multicolored elements printed intaglio. In particular, there are multi-tone elements around and under the portrait of Lord Byron (on the right) as well as around and under the inscriptions "CTIP" and "COMPUTER TO INTAGLIO PLATE" (on the left), as well as a set of other intaglio elements exploiting the possibilities offered by CTiP® technology. This specimen illustrates the degree of complexity of the elements that can be achieved by intaglio printing, in particular by the aforementioned CTiP® process.

• la qualité et la complexité du substrat à imprimer, en particulier l'intégration d'éléments de sécurité de plus en plus variés et nombreux ;
• les encres taille-douce qui présentent typiquement des variations de viscosité, des formulations différentes, diverses propriétés de séchage, etc. ;
• les réglages machines, en particulier la pression d'impression, l'encrage, les réglages des contacts, la température, etc.

A difficulty resulting from the availability of modern techniques for the realization of intaglio elements lies in the fact that the engraver (we can also speak of "designer" insofar as the intaglio security design is from now on realized in a computer environment) has an almost unlimited freedom in particular regarding the definition of dimensions (line width, depth, etc.) and profiles (square, "U", "V", etc.). ) engravings. This freedom is however not directly transferable to the printing, namely that any type of engraving is not necessarily printable. Intaglio printing remains subject to physical and mechanical constraints that can not be overcome. By way of extreme illustration, it is theoretically possible to design and produce engravings of small width and great depth, for example an engraving having a line width of 10 μm for a depth of 100 μm, but such a structure can hardly to be inked and can not be properly printed to the extent that the substrate can not deform to "seek" the ink in such an engraving. Similarly, a large area etching (several mm ² ) is not printable without adequate structures for retaining the ink inside the etching. Indeed, in the absence of such ink retaining structures, the wiping of the intaglio printing plate would then lead to excessive evacuation of the ink applied to the interior of the etching. Compromises must therefore be made in practice, these compromises implying in particular a certain correlation between the line width, the etching depth, and the etching profile. These trade-offs must also consider the entire security design to print in intaglio, because even though an individual item is potentially printable with certain print settings, these print settings might not be suitable for printing. printing of other elements of the safety drawing. The quality of an intaglio print is thus directly related to the quality of realization of the plate. It should also be noted that other factors influence the quality of intaglio printing, namely:

• the quality and complexity of the substrate to be printed, in particular the integration of increasingly varied and numerous security features;
• platinum inks which typically exhibit viscosity variations, different formulations, various drying properties, etc. ;
• machine settings, especially printing pressure, inking, contact settings, temperature, etc.

With regard to the machine settings, the printer must in particular carry out an adjustment of the printing pressure (that is to say the pressure exerted between the intaglio printing plate and the substrate to be printed), the ink charge (i.e., the amount of ink applied to the intaglio printing plate), as well as the wiping. These print settings significantly affect the result of intaglio printing. Controlling these various print parameters is therefore crucial, in particular to ensure good print repeatability and to avoid excessive variations in print quality.

1. (i) s'assurer que l'ensemble des gravures formant le dessin de sécurité à imprimer en taille-douce soient effectivement imprimables (l'on peut alors parler d'une vérification de l'imprimabilité du dessin de sécurité et d'une validation des gravures) ; et
2. (ii) s'assurer par ailleurs que l'ensemble des éléments taille-douce formant le dessin de sécurité puissent être imprimés avec une régularité et une qualité constante, et ceci avec des paramètres d'impression les plus adaptés à une production de masse (l'on peut alors parler d'une vérification de la répétabilité et de la variabilité de l'impression).

In practice, the printer is therefore essentially confronted with two main problems, namely:

1. (i) ensure that all engravings forming the security print to be intaglio printed are indeed printable (it is then possible to speak of a verification of the printability of the safety drawing and a validation engravings); and
2. (ii) also ensure that all the intaglio elements forming the safety pattern can be printed with a regularity and a constant quality, and this with printing parameters most suitable for mass production ( one can then speak of a verification of the repeatability and the variability of the printing).

This however requires that the printer can objectively evaluate and measure these characteristics on the final result as printed.

The present invention aims to meet these needs.

STATEMENT OF THE INVENTION

A general object of the present invention is therefore to improve the techniques and solutions of the prior art.

More particularly, an object of the present invention is to propose a solution enabling a printer to evaluate and measure in an objective (and quantifiable) way the capacity of a security design that can be printed intaglio.

Furthermore, an object of the present invention is to propose a solution enabling a printer to objectively perform the basic adjustment of an intaglio printing press for the printing of a safety drawing, by example a bank note, based on objective and measurable control elements.

Another object of the present invention is to propose a solution enabling a printer to evaluate and measure in an objective (and quantifiable) manner the effects of intaglio print parameters on the printed result, in particular the equilibrium. between the printing pressure and the ink charge as reflected on the printed result.

Yet another object of the present invention is to propose a solution enabling a printer to quantify the variations in quality, density, positive and negative fattening of the printed lines (or "line gain") with respect to an expected result. and thus to limit or mitigate the effects of these variations on the print quality, thus ensuring a good repeatability of the print.

Another object of the present invention is to propose a solution enabling a printer to identify and objectively and quantifiably diagnose the probable source of a possible printing problem, by relying on objective control means and measurable to allow it to include or exclude potential causes of the potential printing problem.

The present invention serves these purposes by providing a method for controlling an intaglio printing whose characteristics are set forth in independent claim 1.

1. (i) l'encrage d'au moins une plaque d'impression taille-douce avec au moins une encre taille-douce ;
2. (ii) l'essuyage de la plaque d'impression taille-douce ainsi encrée ; et
3. (iii) l'impression d'un substrat au moyen de la plaque d'impression taille-douce ainsi essuyée, l'impression du substrat impliquant l'application du substrat contre la plaque d'impression taille-douce à une haute pression d'impression.

By "intaglio printing" within the meaning of the invention, it is necessary to understand a printing process involving:

1. (i) inking at least one intaglio printing plate with at least one intaglio ink;
2. (ii) wiping the intaglio printing plate thus inked; and
3. (iii) the printing of a substrate by means of the intaglio printing plate thus wiped off, the printing of the substrate implying the application of the substrate against the intaglio printing plate at a high pressure of impression.

In this context, printing pressure, ink charge, and wiping are print parameters that can affect intaglio printing.

1. (a) la définition sur la plaque d'impression taille-douce de plages de contrôle conçues de manière à permettre notamment d'évaluer les effets de la pression d'impression appliquée lors de l'impression (iii) du substrat et d'évaluer les effets de la charge d'encre appliquée lors de l'encrage (i) de la plaque d'impression taille-douce, lesquelles plages de contrôle sont gravées dans une portion de la plaque d'impression taille-douce afin de produire des zones de contrôle imprimées correspondantes sur le substrat ;
2. (b) la réalisation de mesures dans les zones de contrôle imprimées permettant d'évaluer si la pression d'impression appliquée lors de l'impression (iii) du substrat est adéquate ou non ; et
3. (c) la réalisation de mesures dans les zones de contrôle imprimées permettant d'évaluer si la charge d'encre appliquée lors de l'encrage (i) de la plaque d'impression taille-douce est adéquate ou non.

The method according to the invention thus comprises the following steps:

1. (a) the definition on the intaglio printing plate of control ranges designed to allow in particular to evaluate the effects of the printing pressure applied during the printing (iii) of the substrate and to evaluate the effects of the ink charge applied during the inking (i) of the intaglio printing plate, which control strips are etched in a portion of the intaglio printing plate to produce zones corresponding printed control boards on the substrate;
2. (b) performing measurements in the printed control areas to evaluate whether or not the printing pressure applied during printing (iii) of the substrate is adequate; and
3. (c) performing measurements in the printed control areas to assess whether the ink charge applied during the inking (i) of the intaglio printing plate is adequate or not.

Preferably, the printing pressure and the ink charge are adjusted until the measurements made in the printed control areas reflect an optimal balance between the printing pressure and the ink charge. Such optimal equilibrium is in particular preferably determined on the basis of measurements made in the printed control areas, which measures include a measurement of optical density (or "optical density "), of line cleanliness (or "raggedness "). and the fill rate of line (or " fill ").

With regard to the ink charge, in the event that the intaglio printing plate is inked by means of a plurality of different inks (which is typically the case in practice), the control ranges include at least one control range for each ink used, and measurements made in the printed control areas are made for each ink individually.

According to a preferred variant of the invention, the measurements made in the printed control areas include the measurement of a line cleanliness (" raggedness "), the measurement of a fill rate ("fill"), and the measurement of an optical density according to a given measurement standard, in particular according to ISO / IEC 13660: 2001 or ISO / IEC TS 24790: 2012 (which cancels and replaces ISO / IEC 13660: 2001). Advantageously, the measurement of the line cleanliness (" raggedness "), the measurement of the fill rate of the line (" fill ") as well as the measurement of the optical density (" optical density") are performed on printed lines oriented substantially at ± 45 ° with respect to a printing direction and preferably having a line width of between 30 μm and 200 μm.

On the other hand, it is also advantageous that the measurements made in the printed control areas further include the measurement of a contrast, which measurement allows an objective evaluation of the printability of multi-tone elements.

The measurements made in the printed control areas should preferably make it possible to constitute a sampling of measurements representative of the printing of engravings of various depths, in particular engravings whose depth varies within a range of values less than or equal to 70 μm.

According to an advantageous variant of the invention, the method further comprises a step of verifying the printability of a security design to be printed intaglio by means of the intaglio printing plate, provided that the measurements made in the printed control areas show that the print parameters are adequate.

According to another advantageous variant of the invention, the printing parameters of an intaglio printing press are checked and, if necessary, adjusted, according to the measurements made in the printed control areas.

The present invention also fulfills the above-mentioned purposes by providing a control range whose characteristics are set forth in independent claim 11. Advantageous variants of this control range are presented in the following description and are the subject of the dependent claims.

The control range according to the present invention finds a particularly advantageous application for the purpose of allowing a verification of the printability of a security design to be printed in intaglio by means of an intaglio printing plate provided with the control range.

The control range according to the present invention finds another particularly advantageous application for the purpose of allowing the control and, where appropriate, the adjustment of the printing parameters of an intaglio printing press, in particular of the pressure printing and ink charge.

The control range according to the present invention also finds an advantageous application for the purpose of enabling quality control of the intaglio printing plate itself.

The present invention also relates to an etched plate for intaglio printing, in particular an intaglio printing plate or an intaglio printing plate precursor, comprising the abovementioned control range made in a portion of the plate. etched, the control pads being etched in the portion of the engraved plate, preferably in a portion forming a margin on an end portion of the intaglio printing plate.

The present invention furthermore relates to any digital origination file intended for the production of an intaglio printing plate, comprising a set of digital data representative of a safety drawing to be engraved, as well as a set of numerical data representative of the aforementioned control range.

Other aspects of the invention are the subject of the dependent claims.

SUMMARY DESCRIPTION OF THE DRAWINGS

• la Figure 1 montre une image en demi-teintes d'un spécimen de billet de banque avec le portrait de Lord Byron tel que produit par la Demanderesse et distribué au public durant l'année 2003 ;
• la Figure 2 montre une vue schématique d'une presse d'impression taille-douce telle qu'utilisée pour la production de papiers-valeurs, en particulier de billets de banque ;
• la Figure 3 montre une vue schématique de l'unité d'impression taille-douce de la presse d'impression illustrée dans la Figure 2 ;
• la Figure 4 est une illustration schématique d'une plaque d'impression taille-douce munie d'une gamme de contrôle selon l'invention ;
• la Figure 5 illustre schématiquement un exemple de réalisation d'une gamme de contrôle comportant plusieurs plages de contrôle selon un premier mode de réalisation de l'invention ;
• la Figure 6 illustre schématiquement des zones de contrôle imprimées résultant de l'impression de la gamme de contrôle de la Figure 5;
• la Figure 7 illustre schématiquement un autre exemple de réalisation d'une gamme de contrôle comportant plusieurs plages de contrôle selon un second mode de réalisation de l'invention ;
• la Figure 8 est un diagramme schématique illustrant les étapes d'un procédé visant à ajuster les paramètres d'impression d'une presse d'impression taille-douce selon un exemple de mise en oeuvre de l'invention ;
• la Figure 9 est un vue schématique illustrant une mesure de la propreté de ligne, une mesure du taux de remplissage, ainsi qu'une mesure de densité optique d'une ligne imprimée au titre d'élément de contrôle ; et
• la Figure 10 est un diagramme schématique illustrant la variation de la réflectance mesurée selon la ligne 1-1 dans la Figure 9.

The features and advantages of the present invention will emerge more clearly on reading the following detailed description of embodiments of the invention, presented solely by way of nonlimiting examples and illustrated by the appended drawings in which:

• the Figure 1 shows a halftone image of a banknote specimen with the portrait of Lord Byron as produced by the Claimant and distributed to the public during the year 2003;
• the Figure 2 shows a schematic view of an intaglio printing press as used for the production of securities, particularly banknotes;
• the Figure 3 shows a schematic view of the intaglio printing unit of the printing press illustrated in FIG. Figure 2 ;
• the Figure 4 is a schematic illustration of an intaglio printing plate provided with a control range according to the invention;
• the Figure 5 schematically illustrates an exemplary embodiment of a control range comprising several control ranges according to a first embodiment of the invention;
• the Figure 6 schematically illustrates printed control areas resulting from the printing of the control range of the Figure 5 ;
• the Figure 7 schematically illustrates another embodiment of a control range comprising several control ranges according to a second embodiment of the invention;
• the Figure 8 is a schematic diagram illustrating the steps of a method for adjusting the print parameters of an intaglio printing press according to an exemplary implementation of the invention;
• the Figure 9 is a schematic view illustrating a measure of line cleanliness, a fill rate measurement, and an optical density measurement of a printed line as a control element; and
• the Figure 10 is a schematic diagram illustrating the variation of the reflectance measured along the line 1-1 in the Figure 9 .

MODES FOR CARRYING OUT THE INVENTION

The Figure 2 schematically illustrates an intaglio printing press generally designated by reference numeral 1. More specifically, the Figure 2 shows an intaglio printing press 1 to the sheet comprising a sheet feed unit 2 for feeding sheets to be printed, an intaglio printing unit 3 for printing the sheets, and a sheet delivery unit 4 to collect the freshly printed sheets. The intaglio printing unit 3 comprises a printing cylinder 7 (three-segment), a plate cylinder 8 (in this example, it is a three-segment cylinder carrying three plates). intaglio printing), an inking system comprising an ink collecting cylinder, or Orlof cylinder, 9 (here it is a three-segment blanket cylinder carrying a corresponding number of blankets) for the inking of the surface of the intaglio printing plates carried by the plate cylinder 8, and an ink wiping system 10 for wiping the inked surface of the intaglio printing plates carried by the plate cylinder 8 , before printing leaves.

The sheets are fed from the sheet feed unit 2 to a feed table, or feeder, and then transferred one by one to the printing cylinder 7. The sheets are then conveyed by the printing cylinder 7 to the point where between the printing cylinder 7 and the plate cylinder 8, where the intaglio printing itself takes place. Once printed, the sheets are transferred from the printing cylinder 7 to a sheet conveyor system 15 for transport and delivery to the sheet delivery unit 4. The sheet conveyor system 15 conventionally includes a system sheet conveyor comprising a pair of chains without end resulting in a plurality of spaced apart gripper bars holding the sheets by their front portion (the freshly printed face of the sheets being downwardly oriented during the path of the sheets from the printing unit 3 to the sheet issuing unit 4 ), the sheets being transferred successively to a corresponding clamp bar of the conveyor system.

During their transport to the leaf issuing unit 4, the freshly printed sheets are preferably inspected by an optical inspection system 5. In the example illustrated, the optical inspection system 5 is advantageously a compliant inspection system. to that disclosed in the international application published under No. WO 2011/161656 A1 , which inspection system 5 includes a transfer mechanism and an inspection drum located at a transfer section between the impression cylinder 7 and the chain drive wheels of the sheet conveyor system 15. The system inspection 5 may alternatively be arranged on the path of the sheet conveyor system 15, for example in the image of inspection systems described in international applications published under nos. WO 97/36813 A1 , WO 97/37329 A1 , and WO 03/070465 A1 . Such inspection systems are in particular marketed by the Applicant under the designation of NotaSave® product.

Prior to delivery, the printed sheets are preferably transported in front of a drying or curing unit 6 disposed after the inspection system 5 along the transport path of the sheet conveyor system 15. Drying or curing could if necessary, be carried out before the optical inspection of the sheets.

The Figure 3 is a schematic view of the intaglio printing unit 3 of the intaglio printing press 1 of the Figure 2 . As already noted, the printing unit 3 essentially comprises the printing cylinder 7, the plate cylinder 8 with its printing plates intaglio system with its ink collecting cylinder 9, and the ink wiping system 10. As can be seen from

Figure 3 , the printing cylinder 7 and the plate cylinder 8 (as well as the ink collecting cylinder 9) are three-segment cylinders 7b, resp. 8b, each presenting three pits 7a, resp. 8a, where are typically the retaining means necessary for mounting the blankets (in the case of the printing cylinder 7 or the ink collecting cylinder 9) or intaglio printing plates (with respect to the cylinder door -plate 8).

The inking system comprises in this example five inking devices 20, all of which cooperate with the ink collecting cylinder 9 which is in contact with the plate cylinder 8. It will thus be understood that the inking system illustrated is adapted for the indirect inking of the plate cylinder 8, namely intaglio printing plates, via the ink collecting cylinder 9. The inking devices 20 each comprise an inkwell comprising an inkwell roller 21 cooperating in this example with a pair of ink application rollers 22. Each pair of ink application rollers 22 in turn ink a corresponding pinch cylinder 23 which is in contact with the ink collecting cylinder 9. As is customary in the field, the surface of the stencil cylinders 23 is structured so as to have portions in relief corresponding to the areas of the intaglio printing plates to receive the corresponding color inks provided by r inking devices 20.

As illustrated in Figures 2 and 3 both the printing cylinder 7 and the plate cylinder 8 are supported by a stationary (main) frame 50 of the printing press 1. The inking devices 20 (including the ink fountain roller 21 and ink application rollers 22) are in turn supported in a mobile inking carriage 52, while the ink collecting cylinder 9 and the stencil cylinders 23 are supported in an intermediate carriage 51 located between the inking carriage 52 and the stationary frame 50. The inking carriage 52 and the intermediate carriage 51 are advantageously suspended under support rails. In the Figure 2 , numeral 52 'designates the inking carriage in a recessed position indicated in broken lines. It is understood that the intermediate carriage 51 is also mobile.

The double carriage configuration of the intaglio printing press 1 as illustrated in FIGS. Figures 2 and 3 corresponds essentially to the configuration described in the international applications published under Nos. WO 03/047862 A1 , WO 2011/077348 A1 , WO 2011/077350 A1 and WO 2011/077351 A1 .

The ink wiper system 10 typically includes a wiper, wiper (or roller) 11 supported on and partially located in the wiper tub to engage the platen roller 8, cleaning means (not shown) for removing ink residues wiped from the surface of the wiper roll 11, and a drying blade (not shown) placed in contact with the surface of the wiper roll 11 to remove the solution residues for wiping the surface of the wiping cylinder 11. An exemplary embodiment of a particularly suitable wiping system is described in the international application published under No. WO 2007/116353 A1 .

A schematic example of an intaglio printing plate, generally designated by the reference numeral 80, is illustrated in FIG. Figure 4 . This printing plate 80 is typically made of a suitable metal (for example nickel) whose surface is provided with a wear resistant coating (for example a chromium coating). As illustrated, the front and end ends of the intaglio printing plate 80 (relative to the direction of printing indicated by the arrow I in the Figure 4 ) are provided with a set of orifices for fixing the intaglio printing plate 80 on the circumference of a plate cylinder of an intaglio printing press (like the plate cylinder 8 of the Figures 2 and 3 ).

Suitable means are conventionally used to carry out engravings in the surface of the printing plate 80. These engravings can advantageously be made according to the principles set forth in the international applications published under Nos. WO 03/103962 A1 and WO 2009/138901 A1 , already mentioned above, both of which relate to the CTiP® technique developed by the Applicant. Other techniques may, however, be used to perform these etchings, and the present invention is not specifically limited to a particular etching technique.

Reference numeral 100 in the Figure 4 designates an individual security design, very schematically represented by a simple rectangular shape, corresponding to a security impression to be made, for example a bank note, like the image shown in FIG. Figure 1 . Reference numeral 100A denotes the set of safety drawings 100, repeated, as is conventionally the case, in the form of a matrix arrangement (here comprising five columns and eight rows), which is intended to be printed on the sheets .

Reference numeral 150 (as well as reference numeral 170) designates a control range according to the invention illustrated very schematically, an essential function of which is to enable a printer to perform, on the sheets printed by means of the plate Intaglio print 80, various measures relating to intaglio printing. In the Figure 4 it can be seen and noted that the control range 150 (170) is made in this example on the end portion of the printing plate 80, so that the corresponding print appears on the end portion of the sheets.

The Figure 5 schematically illustrates an exemplary embodiment of a control range, generally designated by the reference 150, according to a first embodiment of the invention, variants being however possible (in the image of the other example shown in FIG. Figure 7 ) without departing from the scope of the invention defined by the appended claims.

The control range 150 illustrated in the Figure 5 comprises a set of control ranges distributed in a direction perpendicular to the printing direction I. More specifically, these control ranges consist of a predetermined set of control elements (here five in number) designated by the references A at E in the Figure 5 , which are repeated several times transversely to the printing direction I, as illustrated on the upper part of the Figure 5 .

The various control ranges of the control range are each intended to be inked by means of a specific ink. In the illustrated example, the inks are five in number (which corresponds to the number of inking devices 20 in the intaglio printing press 1 of the Figures 2 and 3 ). References ① to ⑤ in the Figure 5 designate the ink by means of which each control range is inked.

The lower part of the Figure 5 is an enlarged view of the first five control ranges, designated by numerals 151 to 155, at the left end of the control range 150. The first control range 151 incorporates the characteristics of the first control element A. Similarly, the second to fifth control ranges 152 to 155 respectively take the characteristics of the second to fifth control elements B to E. The other control ranges of the control range 150, to the right of the control range 151, such as represented on the upper part of the Figure 5 , are not detailed on the lower part of the Figure 5 because they take the same structures as those of beaches 151 to 155. illustrative, the dimensions of each control range are of the order of 4 mm in height and 5 mm in width.

More specifically, in the example shown, the control areas 154, 155, 153 (which respectively correspond to the control elements D, E, C) at the left end of the control range 150 form a set which is inked with the same first intaglio ink ①. This is further represented by an index to ₁ on the right side of the control range 153, a corresponding index being provided to identify the intaglio ink used for inking each range or set of control ranges. The control range 152 (corresponding to the control element B) is in turn inked by means of a second intaglio ink ②, while the control range 151 (corresponding to the control element A) is inked by means of a third intaglio ink ③, this being represented by an index corresponding to ₂ , respectively to ₃ , on the right side of the control range 152, respectively 153. These permutations between control elements A to E and inks ① to ⑤ are continued over the entire control range 150. Thus, for example, the two control ranges immediately to the right of the control range 151 (which are not represented on the lower part of the control range 150). Figure 5 ), correspond to the control elements C and B (and have the same structures as those of the control areas 153 and 152, except the indicative index of the ink) respectively inked by means of a fourth intaglio ink ④ and of a fifth intaglio ink ⑤, as shown on the upper part of the Figure 5 .

Various permutations are made so that at least a portion of the control elements A to E are restored as control pads inked with all five inks taille to ⑤. In the example shown in the Figure 5 , only the control elements A to C are restored in the form of control inked with the five inking intaglio ① to ⑤. The control elements D and E are only returned in the form of control areas inked with the first intaglio ink ① (like the control areas 154 and 155). This is an example of a non-limiting embodiment, and it is perfectly possible that all the control elements A to E are rendered in the form of control ranges inked by means of five inks intaglio ① to ⑤.

As will be understood below, it is above all, in the context of the present invention, to provide control ranges designed to allow in particular to evaluate the effects of the printing pressure applied during printing. of the substrate and to evaluate the effects of the ink charge applied during the inking of the intaglio printing plate 80. For these purposes, the control ranges of the control range 150 comprise a set of lines and / or curves having orientations and dimensions (width and / or depth) varied, to perform the desired measurements.

According to a preferred embodiment of the invention, the lines and / or curves are selected with particular regard to the following considerations.

In the first place, the intaglio printing depends on a vital factor, namely the printing pressure. The printing pressure has the effect of pushing the substrate more or less deeply inside the engravings to come into contact with the ink therein. Excessive printing pressure typically has the effect of potentially causing ink to spill out of the engravings (commonly referred to as "spitting"), which affects the sharpness and cleanliness of the printed lines. This overflow, or spitting, is also influenced by the amount of ink actually present in the engravings.

A balance must therefore be found between the printing pressure and the ink charge so as to ensure that both the thin (and shallow) lines and the wide (and deeper) lines can be properly printed. The spitting phenomenon may indeed occur due to excessive ink loading and / or excessive printing pressure, as these two print parameters may individually or jointly lead to overflow. ink outside engravings.

However, it can also be seen that the variations in the ink charge, beyond a minimum level, are not very visible in the fine and shallow engravings because, even with a light inking, these engravings are generally well inked. . The amount of ink is determined by the volume of the engravings and the action of the wiper. Thus, even if a large quantity of ink is transmitted to the plate, it is not possible to fill the engravings beyond the volume available and the surplus off the engravings is removed during wiping. In other words, it is possible in particular to evaluate the effects of the printing pressure by examining the printing of fine and shallow engravings, the print quality of these engravings being, as it were, not affected. by the ink charge beyond the minimum ink level sufficient to inking said fine and shallow engravings.

It will further be noted that the nature of the intaglio inks used, the viscosity of which may vary in particular, also has an influence on the spitting phenomenon. Furthermore, the orientation of the lines (or curves) etched in an intaglio printing plate and their profile (typically "V", "U" or square) have an influence on the degree of printability of the engravings in question.

Indeed, in the fiduciary industry, where cotton-based paper is still widely used, it is customary to use "broadband" paper (or "BL" paper). that is, paper that when cut into sheets, has fibers whose orientation is typically perpendicular to the longer side of the sheets (which largest side is itself conventionally oriented perpendicular to the direction of printing). In other words, the fiduciary paper fibers are typically oriented substantially parallel to the printing direction I (i.e., substantially 0 ° to the printing direction I). Paper fi ber fibers have been found to provide some resistance to paper penetration in intaglio print plate etchings. Due to the typical orientation of the paper fibers at 0 ° to the printing direction 1, the resistance of the paper to penetrate the engravings is less for essentially vertically oriented engravings (ie engravings). substantially parallel to the printing direction I). Conversely, the resistance of the paper to penetrate the engravings is greater for etchings orientated essentially horizontally (that is to say engravings substantially perpendicular to the printing direction I).

That being so, the printing direction I also coincides with the wiping direction, with the consequence that the vertically oriented engravings typically contain less ink than the substantially horizontally oriented engravings, which are perpendicular to the wiping direction. and therefore retain the ink better.

These general considerations have therefore been taken into account in designing the control elements A to E represented in the Figure 5 .

With regard to the control element A, rendered in particular in the form of the control range 151 in the Figure 5 here it is a question of making a set of horizontal lines (that is to say perpendicular to the wiping direction I). By way of illustration, this is a set of twenty lines having a line thickness (lw) of the order of 100 μm and a line spacing (ls) of the order of 100 μm. a line density of the order of 50 lines / cm. Preferably, the element of A control is subdivided into four quarters and the line depth (ld) is different for each quarter, in a range of values preferably less than or equal to 40 microns. By way of example, four quarters of the control element A have depths of 12 μm, 18 μm, 25 μm and 35 μm.

The control element A is mainly used to perform contrast measurements between the different quarters composing the control element, and thereby to evaluate the print quality of multi-tone elements. As a reminder, a multi-tone element is generally printed using a single intaglio ink and has tonal variations typically resulting from a variation in engraving depth in a range of values of the order of some microns to about 40 μm. The control element A replicates the typical variations of depths of engraving used for the creation of multi-tone elements.

The control element D, restored in particular in the form of the control range 154 in the Figure 5 is, so to speak, similar to the control element A, with however horizontal lines having a line thickness (lw) less (for example of the order of 60 microns) and a higher line density. As such, the control element D replicates, not in its form but in the values of line width, line spacing and depths, typical values for the printing of micro-texts. This control element D is subdivided into four quarters, with a level of printability decreasing, that is to say that the decreasing printability makes the quarter concerned more difficult to print than the previous quarter, and therefore requires a increased printing pressure. The control element D thus allows a control of the printing pressure on four levels. In the example illustrated, the control element D is only printed by means of the first intaglio ink ①. The printability of the control element D can be evaluated with the naked eye or, preferably, by a measurement of the line filling (" fill ") as explained below. The correct printing, that is to say without broken or broken lines, of at least one of the four fourths composing the control element D lays the foundation for a pressure adjustment adapted to the printing of 'fine elements, such as micro-texts.

The control elements B and C, restored in particular in the form of the control ranges 152 and 153 in the Figure 5 , for their part consist of a set of lines oriented at ± 45 ° with respect to the printing direction I (is in the wiping direction). This orientation at ± 45 ° of the lines is particularly advantageous in the context of the present invention, insofar as these lines have a median position which is neutral with respect to the orientation of the fibers of the paper and with respect to the wiping direction. . Measurements made by means of the control elements B and C must thus make it possible to overcome to a certain extent the effects of the fibers of the paper and the direction of wiping. These control elements B and C serve mainly to measure the balance between the printing pressure and the ink charge. As will be seen below, the measurements preferably include measuring a line cleanliness (or "raggedness "), a line fill rate (or "fill "), and an optical density (or " Optical density ") lines.

With regard more particularly to the control element C, reference is made here, by way of illustration, of a set of lines at ± 45 ° having a line thickness (lw) of the order of 200 μm and a spacing line (ls) of the order 160 μm. With regard to the control element B, it is a question, again for illustrative purposes, of a set of lines at ± 45 ° with a line thickness (lw) of the order of 100 μm and a spacing of line (ls) of the order 160 μm. Preferably, the control elements B and C are also subdivided into four quarters and the line depth (ld) is different for each quarter, within a range of values less than or equal to 70 μm (it being specified that engraving depths up to 100 μm or more are also possible). This is advantageously a representative range of two types of lines that are characterized by a radically different behavior in terms of printability. Indeed, wide lines (such as those that characterize the control element C) have a natural tendency to allow the substrate to penetrate deeper into the engravings. Consequently, a disturbance of the balance between print pressure and ink charge will be more rapidly apparent on the wide lines of the control element C than on the thinner lines of the control element B. In other words, the 200 μm lines constituting the control element C are more sensitive to variations in the equilibrium between the printing pressure and the ink charge than the 100 μm lines constituting the control element B. Moreover, the various quarters constituting the control elements B and C advantageously make it possible to constitute a sampling of measurements (in particular line cleanness, line filling rate, and optical density measurements). lines) representative of the printing of engravings of various depths, in particular engravings whose depth varies within a range of values less than or equal to 70 μm. In the case in point, each control element B and C makes it possible to form a sampling of four measurements (one for each quarter).

The fifth control element E, restored in particular in the form of the control range 155 in the Figure 5 , is for illustrative purposes a set of horizontal lines (with a line density comparable to the lines of the control element D) combined with a pictorial pattern (here a portion of a pattern representing a pegasus). This element makes it possible in particular to check the printability of two-tone patterns by a visual appreciation.

The Figure 6 schematically illustrates an example of an impression of the control range 150 of the Figure 5 , the printing of the control range 150 being generally designated by the reference numeral 160. As will be readily understood, the various control ranges presented above are thus restored, after intaglio printing of the substrate, in the form of a set of printed control areas corresponding to the various control elements A to E printed in the various colors corresponding to the intaglio inks ① to ⑤ used. In particular, each control range corresponds to a corresponding printed control zone, the reference numerals 161 to 165 thus denoting the printed control areas corresponding respectively to the control ranges 151 to 155 of the Figure 5 . The sets of lines and / or curves constituting the control ranges are thus restored in the form of corresponding sets of lines and / or printed curves, on which it is possible to perform measurements, as discussed below.

The Figure 7 schematically illustrates another embodiment of a control range according to a second embodiment of the invention, which control range is designated generally by the reference numeral 170.

Like the control range 150 illustrated in the Figure 5 , the control range 170 illustrated in the Figure 7 comprises a set of control ranges distributed in a direction perpendicular to the printing direction I. More specifically, these control ranges consist of a predetermined set of control elements (here nine in number) designated by the references K at S in the Figure 7 , which are repeated several times transversely to the printing direction I, as illustrated on the upper part of the Figure 7 .

The various control ranges of the control range are each intended to be inked by means of a specific ink. In the illustrated example, the inks are again five in number and the references ① to ⑤ again designate the ink by means of which each control range is inked.

The lower part of the Figure 7 is an enlarged view of the first nine control ranges, denoted by the reference numerals 171 to 179, at the left end of the control range 170. The first control range 171 has the characteristics of the first control element K. Likewise the second to ninth control areas 172 to 179 have the characteristics of the second to ninth control elements L to S. The other control ranges of the control range 170, to the right of the control range 171, as shown on the upper part of the Figure 7 , are not detailed on the lower part of the Figure 7 since they take up the same structures as those of the ranges 171 to 179. By way of illustration, the dimensions of the control ranges 171 to 177 are of the order of 4 mm in height and 4 mm in width, whereas the dimensions of the two ranges 178 and 179, present only at both ends of the control range 170, are of the order of 4 mm in height and 5 mm in width.

Various permutations are again made so that at least a portion of the control elements K to S are restored as control pads inked with all five inks taille to ⑤. In the example shown in the Figure 5 only the control elements K and M to Q are reproduced in the form of control areas inked by means of the five intaglio inks ① to ⑤. The control elements L, R and S are in turn restored in the form of control areas inked with a single or only part of the intaglio inks ① to ⑤. This is another example of a non-limiting embodiment.

The control ranges of the control range 170 make it possible once again to evaluate in particular the effects of the printing pressure applied during the printing of the substrate, and to evaluate the effects of the ink charge applied during the inking of the intaglio printing plate 80.

In view of the considerations mentioned above, the control elements K to S have been designed as follows.

As regards the R and S control elements, in particular in the form of the control ranges 178 and 179 in the Figure 7 , they have the same characteristics as the control elements E and D of the Figure 5 . With regard to the control element K, restored in particular in the form of the control range 171 in the Figure 7 , in this example, it is a question of making a set of horizontal lines (that is to say perpendicular to the wiping direction I) similar to the set of lines forming the control element R. As an illustration in this other example, it is a set of lines having a line thickness (lw) of the order of 60 microns and a line spacing (ls) of the order of 60 microns. Preferably, the control element K (as well as the control element R) is subdivided into four quarters and the line depth (ld) is different for each quarter, in a range of values less than 40 μm. By way of example, four quarters of the control element K (and R) have line depths (ld) of 12 μm, 18 μm, 25 μm and 35 μm. Like the control element D of the Figure 5 , the control elements K and R are mainly used to measure the effects of the printing pressure.

The control elements M to Q, restored in particular in the form of the control ranges 173 and 177 in the Figure 7 , are constituted of a set of lines oriented at ± 45 ° with respect to the printing direction I (in the image of the control elements B and C of the Figure 5 ), subdivided into four quarters. This is again illustrative of lines having a line thickness (lw) of the order of 100 μm (element M) or 200 μm (elements N to Q) and a line spacing (ls) of the order of 160 μm, the line depth (ld ) being varied in a range of values from 8 μm to 70 μm, in the illustrated example.

The control element O shown in the Figure 7 differs significantly from the control elements M, N, P and Q in that right lower quarter is not constituted by lines, but forms a solid area, identified by the reference numeral 180, namely a substantially continuous region consisting of a relatively large surface etching (of the order of 4 mm ² surface in this example) and a depth of the order of 40 microns with a structuring, or grain, etching background of the order of 55 microns at 70 μm. The aim here is to produce a substantially uniform impression in which optical density measurement can be performed. An optical density measurement can also be performed on lines, but the solid 180 has the advantage of a larger area in which it is easier to perform an optical density measurement.

It will again be understood that the various constituent quarters of the control elements M to Q advantageously make it possible to constitute a sampling of measurements representative of the printing of engravings of various depths, in particular engravings whose depth varies within a range of lower values or equal to 70 μm. In the case in point, the control element M makes it possible to constitute a sampling of four measurements (one for each quarter) over four different depth values (for example 20 μm, 35 μm, 50 μm and 70 μm). acting as printed lines having a line thickness (lw) of 100 μm. The control elements N to Q make it possible to constitute a sampling of fifteen measurements (one for each quarter, except the solid 180) on fifteen values of different depths (for example 8 μm, 10 μm, 12 μm, 15 μm , 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm and 70 μm) in the case of printed lines having a line thickness (lw) of 200 μm. In this example, sampling is more important for lines with a line thickness (lw) of 200 μm insofar as these lines are, as already mentioned, more sensitive to changes in the balance between the pressure of print and ink charge than 100 μm wide lines.

The control element L, restored in particular in the form of the control range 172 in the Figure 7 , consists of a set of thin, shallow lines, oriented at ± 45 ° to the direction of printing, which is subdivided into four quarters. In this example, it is a question of lines having a line thickness (lw) and a line spacing (ls) of the order of 30 μm whose line depth (ld) is equivalent to 12 μm, 16 μm, 22 μm or 30 μm, depending on the quarter considered. This control element L may in particular serve as an additional control element for measuring the effects of the printing pressure.

It is obviously understood that an impression of the control range 170 of the Figure 7 , produces a corresponding set of printed control areas reflecting the various control elements K to S printed in the various colors corresponding to the intaglio inks ① to ⑤ used. The sets of lines and / or curves constituting the control ranges of the control range 170 are thus restored in the form of corresponding sets of lines and / or printed curves, on which it is possible to perform measurements, as discussed below. This also applies to the solid 180.

Other variants of the control range beyond the two variants illustrated in FIGS. Figures 5 and 7 are obviously conceivable in the context of the present invention.

The Figure 8 is a schematic diagram illustrating the main steps of a process for adjusting the print parameters of an intaglio printing press (for example a press printing according to the Figures 2 and 3 ) according to an exemplary implementation of the invention.

This method involves first (step S10) the preparation and supplying of an intaglio printing plate (like the intaglio printing plate 80 illustrated in FIG. Figure 4 ) provided with a control range according to the invention, for example the control range 150 or 170 discussed above.

The printer then proceeds (in step S12) to a presetting of the printing parameters of the intaglio printing press, in particular the printing pressure, the ink charge, and the printing press. wiping. These are nominal parameters generally recommended by the manufacturer of the intaglio printing press and which must make it possible to perform an intaglio printing of good quality, it being understood however that a subsequent adjustment of these parameters is necessary. typically required in practice.

Once the nominal parameters have been preset, the printer can proceed to print test sheets (in step S14) by means of the intaglio printing plate provided with the control range.

Once this intaglio printing has been carried out, measurements can then be made (step S16) on the printed control areas corresponding to the control ranges of the control range, in particular for the purpose of checking the printing pressure and the load. ink (step S18), and if necessary to make corresponding adjustments (step S20) before starting a new print.

As already mentioned above, the printer will try in practice to find an optimal balance between the printing pressure and the ink charge, and the measurements made in the printed control areas must in particular make it possible to find this optimal balance. For example, referring to the control range 150 of the Figure 5 , the control element D must make it possible to check whether a minimum printing pressure value is reached, and the control elements B and C must make it possible to quantitatively measure the degree of spitting of the lines, that is to say whether the balance between printing pressure and ink charge is good or not, this on two types of characteristic lines as discussed above. The control element A of the control range 150 completes the analysis by allowing a measurement of the resultant contrast values representative of the balance between printing pressure and ink charge.

According to a preferred embodiment of the invention, the said quantitative measurements are carried out in the printed control zones rendering lines oriented at ± 45 ° with respect to the printing direction I (in the image of the control zones printed 162, 163 restoring the control elements B and C of the control range 150 or the printed control areas restoring the control elements M to Q of the control range 170).

These quantitative measures preferably include the measurement of a line cleanliness, a degree of line filling and an optical density according to a given standard, in particular according to ISO / IEC TS 24790: 2012 (accessible on the site). of the International Organization for Standardization, www.iso.org , which standard is incorporated by reference in this application), the first edition of which was published on August 15, 2012. This standard cancels and replaces the earlier ISO standard / IEC 13660: 2001 which has been technically revised, but remains where relevant for the practice of the present invention.

The cleanliness of the line is in particular measured by determining the "raggedness " within the meaning of clauses 3.28 and 5.3.6 of ISO / IEC TS 24790: 2012. The level of line filling is measured by determining the " fill " within the meaning of clauses 3.12 and 5.3.7 of the ISO / IEC TS 24790: 2012. As for optical density, this is measured according to clauses 3.21 and 3.26 of ISO / IEC TS 24790: 2012. The Figures 9 and 10 to illustrate more concretely what it is about, the Figure 9 schematically illustrating a portion of a printed line designated by reference numeral 200. Although the Figure 9 shows a printed line 200 whose optical density is measured, it is of course understood that the optical density could be measured on any suitable printed structure, in particular a printed area resulting from the printing of the solid color 180 of the Figure 7 .

"Raggedness " according to ISO / IEC TS 24790: 2012 is a measure of the degree of sharpness of a line with respect to a standard line threshold (or "edge threshold"). The measurement of raggedness is carried out according to the guidelines mentioned in clause 5.3.6 of ISO / IEC TS 24790: 2012, namely by first determining the edge threshold defined as the reflectance level, R ₄₀ , in a line reflectance curve (cf. Figure 10 ) corresponding to 40% of the transition of a minimum reflectance value R _min (typically corresponding to the measured reflectance of the printed line 200) to a maximum reflectance value R _max (typically corresponding to the measured reflectance of a non-reflective portion). printed on the substrate), as schematically represented on the Figure 9 . By way of illustration, the two fictional lines 210 in the Figure 9 schematically illustrate the line threshold corresponding to the reflectance value R ₄₀ thus determined. Then, a measurement of the standard deviation of the variations, or " residuals ", 250 with respect to the thresholds of line 210 is carried out, to arrive at a quantification of the " raggedness ".

The " fill " according to ISO / IEC TS 24790: 2012 is a measure of the degree (or rate) of filling of a line, carried out according to the guidelines mentioned in clause 5.3.7 of ISO / IEC TS 24790: 2012.

All the quantitative measurements can be carried out by means of an optical measuring device, generally designated by the reference numeral 500 in the Figure 9 , for example by means of a device type LabQMD as marketed by the Applicant.

The transposition in an intaglio printing plate of the control range and the control ranges according to the present invention can be carried out according to the principles already stated in the international applications. WO 03/103962 A1 and WO 2009/138901 A1 , together with the safety drawing to be printed intaglio. In this context, the transposition can be carried out, preferably by laser etching, either directly in a printing plate or indirectly in a printing plate precursor, this precursor being then used to produce several printing plates by galvanic replication.

As proposed in the international application WO 03/103962 A1 , the transposition of the generated patterns advantageously comprises the generation of a set of three-dimensional digital data consisting of pixels each representative of an elementary point to be etched in the surface of the printing plate or the printing plate precursor, etching as such being operated pixel by pixel on the basis of these three-dimensional digital data.

It is understood that the present invention also encompasses any engraved plate for intaglio printing (especially any intaglio printing plate or intaglio printing plate precursor) having a control range according to the present invention. .

Likewise, the present invention also encompasses any digital origination file intended for the manufacture of an intaglio printing plate comprising a set of digital data representative of a safety drawing to be engraved, as well as a set of numerical data representative of a control range according to the present invention.

It will be understood in general that various modifications and / or improvements obvious to those skilled in the art can be made to the embodiments described in the present description without departing from the scope of the invention defined by the appended claims.

In particular, the invention is not limited to the control ranges and control ranges specifically illustrated in the Figures 5 and 7 . Other control patterns, possibly more complex, can be envisaged, it being understood that the control ranges must essentially make it possible to measure the effects of the intaglio print parameters, in particular the printing pressure and the load. ink. Moreover, the control range can be adapted according to the needs, in particular the number of inks applied to the intaglio printing plate. The invention is as such applicable regardless of the number of inks used.

Moreover, it is conceivable to define at least some control ranges directly in the security drawing to be printed, in place of or in addition to control ranges of a control range as discussed above arranged in the margin of the drawing of FIG. security. The claimed control method is thus not limited to the use of a specific control range, it being noted however that a specific control range arranged in the margin of the safety drawing has the advantage of not affecting the design. as such and not to restrict designers' choices.

It is also understood that the above-mentioned measurements made in the printed control areas can be carried out by means of any suitable measuring tool. It may be a device of LabQMD type as already mentioned above or an inspection table of the type described in the international application published under No. WO 2012/131581 A1 and marketed by the Applicant under the name ColorCheck III. As such, an automated or semi-automated control of the intaglio print quality is perfectly conceivable in the context of the present invention. It could also be envisaged that these measurements are carried out online, during intaglio printing, for example by means of a suitable inspection device placed in the intaglio printing press, in the image inspection system 5 shown on the Figure 2 .

In addition, it is potentially conceivable to provide control ranges for evaluating and measuring the wiping of the printing plate, another parameter characterizing intaglio printing. This being so, it is preferable to evaluate the quality of the wiping on the entire printed substrate and, if necessary, to make corresponding adjustments. Measurement of wiping by one or more control ranges may not necessarily be representative of the wiping quality of the entire printed substrate.

Finally, the present invention is not limited by the type of measurements described above, any other measurement making it possible to quantify the intaglio print quality being conceivable. For example, the techniques described in the international applications published under Nos. WO 2008/146262 A2 and WO 2011/018764 A2 as a means of evaluating the intaglio print quality. The row cleanness, line fill rate, optical density, and, where appropriate, contrast measurements mentioned above, however, prove to be very advantageous in the context of the present invention for quantifying the quality of a print size. soft.

LIST OF REFERENCES USED IN THIS APPLICATION

1

intaglio printing press at the sheet

2

leaf feeding unit

3

intaglio printing unit

4

Leaf delivery unit (with three batteries)

5

optical inspection system (eg NotaSave®)

6

drying or curing unit

7

printing cylinder (three-segment cylinder)

7a

impression cylinder pits 7

7b

print cylinder segments 7

8

plate cylinder (three-segment cylinder with three intaglio printing plates)

8a

pits of the plate cylinder 8

8b

segments of the plate cylinder 8

9

ink collector cylinder / cylinder Orlof (three-segment cylinder)

10

ink wiper system

11

cylinder (or roller) rotary wiper of the ink wiper system 10 (cooperates with the circumference of the plate cylinder 8)

15

sheet conveyor system (sheet conveyor system comprising a pair of endless chains driving a plurality of spaced apart gripper bars holding a front portion of the sheets)

20

(five) inking devices

21

inkwell

22

ink application rollers

23

(five) color-select / color-selector cylinders transferring ink to the collector cylinder 9

50

stationary frame supporting the printing cylinder 7, the plate cylinder 8 and the ink wiper system 10

51

intermediate carriage supporting the ink collecting cylinder 9 and the stencil cylinders 23

52

inking carriage supporting the inking devices 20

52 '

inking carriage 52 in retracted position

80

intaglio print plate / engraved plate

I

print direction (also corresponds to the wiping direction)

100

security drawing (individual ticket)

100A

set of safety drawings 100 made on the same intaglio printing plate 80

150

control range (first variant)

151 to 155

control ranges of the control range 150 (control elements A to E)

160

print corresponding to the control range 150

161 to 165

printed control areas corresponding to the printout of control ranges 151 to 155 (control elements A to E)

A to E

first to fifth control elements of the control range 150 (control ranges 151 to 155 / control areas printed 161 to 165)

170

control range (second variant)

171 to 179

control ranges of the control range 170 (control elements K to S)

K to S

first to ninth control elements of the control range 170 (control ranges 171 to 179)

a ₁

color index / stencil (first intaglio ink / first cylinder chablon)

a ₂

color index / stencil (second intaglio ink / second cylinder stencil)

a ₃

color index / stencil (third ink intaglio / third cylinder chablon)

a ₄

color index / stencil (fourth ink intaglio / fourth cylinder chablon)

a ₅

color index / stencil (fifth ink intaglio / fifth cylinder chablon)

①

inked area with a first intaglio ink (first cylinder chablon)

②

Inked area with a second intaglio ink (second cylinder chablon)

③

Inked area with a third intaglio ink (third cylinder chablon)

④

Inked area with a fourth intaglio ink (fourth cylinder chablon)

⑤

inked area with a fifth intaglio ink (fifth cylinder chablon)

S10

providing an intaglio printing plate provided with a control range according to the invention

S12

presetting the print settings (nominal print settings) of the intaglio printing press

S14

printing of a substrate by means of the intaglio printing plate provided with the control range 150

S16

measurements made in the printed control areas resulting from the printing of the control range

S18

evaluation of printing parameters (printing pressure, ink charge, wiping)

S20

adjustment of print settings

200

printed line (eg printed line oriented at ± 45 ° to print direction I)

lw

line width

is

line spacing

ld

line depth

R _min

minimum reflectance factor (printed area) measured according to ISO / IEC TS 24790: 2012 (clause 3.32, Annex D)

R _max

maximum reflectance factor (unprinted area) measured according to ISO / IEC TS 24790: 2012 (clause 3.30, Annex D)

210

thresholds of line 200 determined according to ISO / IEC TS 24790: 2012 ("edge threshold R ₄₀ ", clause 3.11) / determinant for the measure of line cleanliness ("raggedness", clause 5.3.6)

250

residues ("residuals") on either side of the lines coinciding with the thresholds 210 / determining for the measure of cleanliness of line ("raggedness", clause 5.3.6)

500

measuring device (according to ISO / IEC TS 24790: 2012)

Claims (21)

A method for controlling intaglio printing, in particular for the printing of securities, in particular banknotes, said intaglio printing involving: (i) inking at least one intaglio printing plate (80) with at least one intaglio ink; (ii) wiping the intaglio printing plate (80) thus inked; and (iii) printing a substrate by means of the intaglio printing plate (80) thus wiped off, the printing of the substrate involving the application of the substrate against the intaglio printing plate (80) at a high printing pressure, the printing pressure, the ink charge and the wiping constituting print parameters likely to affect said intaglio printing,
characterized in that the control method comprises the following steps: (a) the definition on the intaglio printing plate (80) of control strips (150, 151-155; 170, 171-179) designed in such a way as to make it possible in particular to evaluate the effects of the pressure of printing applied when printing (iii) the substrate and evaluating the effects of the ink charge applied during the inking (i) of the intaglio printing plate (80), which control ranges (150, 151-155; 170, 171-179) are etched in a portion of the intaglio printing plate (80) to produce corresponding printed control areas (160, 161-165) on said substrate; (b) performing measurements in said printed control areas to evaluate whether the printing pressure applied during printing (iii) of the substrate is adequate or not; and (c) performing measurements in said printed control areas to evaluate whether or not the ink charge applied during the inking (i) of the intaglio printing plate (80) is adequate. The method according to claim 1, characterized in that the printing pressure and the ink charge are adjusted until the measurements made in said printed control areas reflect an optimum balance between the printing pressure and the ink charge. The method according to claim 1 or 2, characterized in that the intaglio printing plate (80) is inked by means of a plurality of different inks, said control areas (150, 151-155; 171-179) comprising at least one control range (151-153; 171-176) for each ink used,
and in that the measurements made in said printed control areas are made for each ink individually. The method according to any one of the preceding claims, characterized in that the measurements made in said printed control areas include the measurement of a line cleanliness (" raggedness "), the measurement of a line filling rate ( " Fill "), and the measurement of an optical density according to a given measurement standard, in particular according to ISO / IEC 13660: 2001 or ISO / IEC TS 24790: 2012. The method according to claim 4, characterized in that the measurement of line cleanliness (" raggedness "), the measurement of the fill rate of the line (" fill "), and the measurement of the optical density (" optical density" ) are performed on oriented printed lines essentially at ± 45 ° with respect to a direction of impession (I) and preferably having a line width (lw) of between 30 μm and 200 μm. The method of claim 4 or 5, characterized in that the measurements made in said printed control areas further include measuring a contrast. The method as claimed in any one of the preceding claims, characterized in that the measurements made in said printed control zones enable a sampling of measurements representative of the printing of engravings of various depths, in particular engravings whose depth varies. in a range of values less than or equal to 70 μm. The method according to any one of the preceding claims, characterized in that it further comprises a step of verifying the printability of a safety pattern (100, 100A) to be intaglio printed by means of the intaglio printing plate (80), since the measurements made in said printed control areas show that the print parameters are adequate. The method according to any one of the preceding claims, characterized in that the print parameters of an intaglio printing press (1) are checked and, if necessary, adjusted according to the measurements made in said printed control areas. The method according to any one of the preceding claims, characterized in that the control ranges comprise control ranges of a control range (150; 170) according to any one of claims 11 to 18 arranged in the margin of a drawing. safety device (100, 100A) and / or control ranges defined directly in the safety drawing (100, 100A). A control range (150; 170) for intaglio printing, in particular for the printing of securities, in particular banknotes, said intaglio printing involving: (i) inking at least one intaglio printing plate (80) with at least one intaglio ink; (ii) wiping the intaglio printing plate (80) thus inked; and (iii) printing a substrate by means of the intaglio printing plate (80) thus wiped off, the printing of the substrate involving the application of the substrate against the intaglio printing plate at a high printing pressure, the printing pressure, the ink charge and the wiping constituting print parameters likely to affect said intaglio printing,
the control array (150; 170) comprising a plurality of control pads (151-155; 171-179) for etching into a portion of the intaglio printing plate (80) and forming on the printed substrate, a corresponding plurality of printed control areas (161-165),
said control areas (151-155; 171-179) being so designed as to permit in particular evaluation and measurement in said printed control areas of the effects of the printing pressure applied during the printing (iii) of the substrate as well as the effects of the ink charge applied during the inking (i) of the intaglio printing plate (80). The control range according to claim 11, characterized in that said control ranges (151-155; 171-179) comprise a set of lines and / or curves of depths (ld) varied, preferably lines and / or curves of which the depth (ld) is varied in a range of values less than or equal to 70 μm. The control range according to claim 12, characterized in that said control ranges (151-155; 171-179) are designed to allow the constitution of a sampling of measurements representative of the printing of engravings of various depths, particular engravings whose depth varies within a range of values less than or equal to 70 microns. The control range according to claim 12 or 13, characterized in that said lines and / or curves also have varied line widths (lw), preferably in a range of values from 30 μm to 200 μm. The control range according to any one of claims 12 to 14, characterized in that at least one control range (151, 154, 155, 171, 178, 179) among said control ranges (151-155; -179) comprises lines oriented in a direction perpendicular to a printing direction (I). The control range according to any one of claims 12 to 15, characterized in that at least one control range (152, 153; 172-177) among said control ranges (151-155; 171-179) comprises lines oriented substantially at ± 45 ° with respect to a printing direction (I). The control range according to any one of claims 11 to 16, characterized in that at least one control range (175) among said control ranges (171-179) comprises a solid area (180) for enabling measurement Optical density . The control range according to any one of claims 11 to 17, characterized in that said control ranges (151-155; 171-179) comprise: at least one print pressure control range (151, 154; 171, 179) comprising a set of thin lines and / or curves and shallow depths, preferably lines and / or curves having a lower line width; or equal to 60 μm and a depth less than or equal to 40 μm; and for each ink used, at least one control range of the balance between printing pressure and ink charge (152, 153, 172-177) comprising a set of lines and / or curves of various depths, preferably lines and / or curves with a line width equal to or greater than 100 μm and the depth of which varies within a range of values less than or equal to 70 μm. Use of the control range (150; 170) according to any one of claims 11 to 18 for verifying the printability of a safety pattern (100, 100A) to be intaglio printed by means of an intaglio printing plate (80) provided with said control range (150; 170),
or for the control and, where appropriate, adjustment of the printing parameters of an intaglio printing press (1). An etched plate (80) for intaglio printing, particularly an intaglio printing plate or an intaglio printing plate precursor, having a control range (150; 170) according to any one of claims 11 to 18 made in a portion of said engraved plate (80), said control strips (151-155; 171-179) being etched in the portion of said engraved plate (80), preferably in a margin portion on a end portion of the intaglio printing plate (80). A digital origination file for manufacturing an intaglio printing plate (80), comprising a set of digital data representative of a security drawing (100, 100A) to be engraved, as well as a set digital data representative of a control array (150; 170) according to any one of claims 11 to 18.

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