EP0091709A1 - Gravure machine for printing currency notes - Google Patents

Abstract

This direct plate printing or copperplate machine comprises a plate carrier cylinder with at least one engraved or etched plate provided with cuts corresponding to the elements of a main design and shallower, finer cuts corresponding to the elements of a safety background, an impression cylinder, an inking roller cooperating with an inking unit and being in direct contact with the plate for inking the cuts corresponding to the elements of the main design, a pre-wiping device and a wiping device, and an inking system for inking the cuts corresponding to the safety background in several colors. This inking system consists of a collector cylinder having a smooth resilient surface cooperating with the engraved or etched plate, this collector cylinder being located, in the direction of rotation of the plate cylinder, ahead of the inking roller and comprising at its outer periphery three color selector cylinders for different colors which comprise in turn relief areas corresponding to the colored areas of the safety background, an inking device being associated with each color selector cylinder. This machine assures a perfect register between the reliefs of the various color areas obtained on the color selector cylinders of hard material for producing for example banknotes printed completely according to the direct plate printing or copperplate method. Due to the presence of hard surface material on the color selector cylinder, there is no limit as to the fineness of the safety background elements.

Description

The invention relates to an intaglio machine for printing, on a sheet or on a roll, of security papers, in particular banknotes, comprising a plate cylinder with at least one engraved plate provided with sizes which represent the elements. a main drawing and shallower and finer sizes representing the elements of a safety bottom, a printing cylinder, at least one inking roller for selecting an inking group cooperating directly with the plate for inking the sizes which represent the elements of the main drawing, a device for wiping the plate and preferably a pre-wiping device as well as another inking system for inking the sizes which represent the safety background in several colors with at least two colors.

In order to increase the security factor against falsification of security papers of all kinds, we were led to manufacture these security papers entirely by means of the intaglio process, because it is much more difficult to falsify a security paper produced completely in size -sweet, so also for security funds.

For this reason, the applicant has already proposed in its French patent No. 1,595,894 a polychrome intaglio printing machine comprising one or more inking devices for inking deep engravings, representing the main design, and two or more inking devices to ink fine engravings, representing the security background.

However, the inking device for the funds is in this case produced by means of plates rotating in contact with the printing plate and fixed in an adjustable manner on a carrying roller for the adjustment of a perfect register and for the correction. from said register. This machine, which, theoretically, should allow printing of valuable paper, intaglio, and in a single pass, proved to be too complicated due to the use of these shots which required a lot of time for their implementation. register, which had to be done manually, which also gave a result of uncertain perfection.

In addition, since according to the intaglio process the printing plate is engraved, hollow, with different engraving depths up to 200 to 250 microns, the selection ink roller must exert a strong pressure against the surface of the printing plate to ensure that all engravings of variable depth are filled with ink to obtain precisely the different printing tones of the same color, which constitutes a unique prerogative to the intaglio process.

This ink roller which acts on the plate must therefore be coated with a relatively soft and elastic material, for example rubber, plastic or other, or about 60 shore to transfer the ink from its surface to that of the size plate. sweet. This ink roller must also transfer the ink of a determined color, only on certain areas of the surface of the engraved plate, this is why we used a roller whose surface was cut according to the outline of the areas to be printed in the respective color, and therefore included parts in relief which received the ink. However, given the relatively soft material of this ink roller and the high pressure it must exert against the intaglio plate to fill the deepest sizes, the fineness of the areas represented by the relief is limited. If this restriction does not present a great disadvantage with regard to the main design since in general the areas of color representing this main design are relatively large, on the other hand, it has hitherto prevented the use of these elastic ink rollers to form the security backgrounds because the areas of the roll carrying very fine cutouts are deformed under the effect of pressure, which affects the quality of the printing. A safety background worthy of the name must be formed by very fine lines and even dots, this is why until now it was impossible to form this safety background with an ink roller arranged very finely.

To avoid this drawback, the applicant has already proposed in its French patent No 1,259,111 a polychrome printing machine comprising inter alia a plate cylinder with which cooperate as many ink units as there are colors to be printed, each ink unit comprising a touch roller with a continuous surface, of elastic material, with which a selection cylinder cooperates, embossing the zones corresponding to those to be printed in a given determined color.

However, the system recommended in the aforementioned patent did not allow the inking of deep engravings for the part of a plate constituting the main design of the banknote or other valuable paper. It turned out that it was impossible to print a single piece of valuable paper with a deeply engraved main design and finely engraved security backgrounds in several colors. In addition, the assembly of the different touch rollers was complicated and the perfect register difficult to obtain.

The object of the present invention is to avoid the drawbacks of the above-mentioned machines by proposing a new machine capable of printing completely intaglio, and in a single pass, of valuable paper having a security background finely engraved in at least two colors, in perfect register between them and in perfect register with the main drawing deeply engraved.

To this end, the machine according to the invention is characterized in that said device for inking the sizes, which represent the elements of the safety bottom, is constituted by a collecting cylinder having a smooth and elastic surface cooperating with the engraved plate, this cylinder being located, in the direction of rotation, in front of said ink roller and comprising at its periphery at least two color selector cylinders different which has reliefs corresponding to the colored areas of the security background, an inking device being associated with each color selector cylinder.

The main advantage of this machine is that it ensures a perfect register between the cuts of the different color zones obtained on the selector cylinders in hard material, cuts obtained either by chemical bite, or by laser, and that the cylinders are in perfect register with the printing plate. In addition, given the hard material of the selector cylinder, there is no limit in the fineness of the elements of the safety bottom. We thus obtain banknotes or other securities entirely printed in intaglio, so not only with regard to the main design, but also the security funds. Due to the delicacy of the design of the security background which it is possible to obtain, this machine makes it possible to produce banknotes or any other fiduciary print very difficult to counterfeit.

With this machine, it is possible to work in industrial production at very high speed since there is no more development to do because the selector rollers and the printing plate are, once prepared and assembled, always in perfect register. In addition, the collecting cylinder allows slight color overlays in absolutely impeccable register.

An embodiment of the object of the invention will be described by way of nonlimiting example, with reference to the accompanying drawing, the single figure of which schematically represents an intaglio machine produced in accordance with the present invention.

The machine shown comprises a plate cylinder 1, which cooperates, in known manner, with a printing cylinder 2. The direction of rotation of the different cylinders is represented by arrows in the drawing. The plate cylinder carries one or more plates engraved on the surface of which are engraved both the main design of the paper to be printed, formed by sizes of variable dimensions and relatively deep, and the security funds formed by very fine sizes, especially consisting of very fine lines or even dots, these sizes being less deep than those constituting the main design.

At the periphery of this plate cylinder 1 are considered in the direction of rotation, a collecting cylinder 3, with a smooth surface, which transfers the color zones of the image from the safety background to the sizes representing this safety background, the complete operation of this collecting cylinder and its other characteristics will be described later. Following the collecting cylinder 3, always considered in the direction of rotation, is the conventional selection inking roller 4, with elastic surface and provided with a single-color inking device 9, and intended for inking the deep sizes representing the main design; this roll 4 is sectioned so as to present raised areas whose the contours correspond exactly to those of the surfaces to be printed. This conventional inking roller 4 is followed by a pre-wiping device 5, then by a wiping device 6, both known per se, which clean the planium and compress the ink in sizes.

The collecting cylinder 3 has, as already mentioned, a smooth surface and is made up or coated with rubber or any other elastic material. On this collecting cylinder 3 are transferred at least two different colors for two zones of different colors of the safety background, this is why it cooperates with as many selector cylinders 7 as there are provided in different colors. In the embodiment shown, the collecting cylinder 3 cooperates with three selector cylinders 7 whose surface is made of hard material, for example hard rubber, plastic or metal, each selector cylinder 7 being sectioned so as to present raised areas whose contours correspond exactly to those of the surfaces to be printed in the respective color. These raised areas are obtained by any known means, for example chemical bite, laser cutting, etc. As the surface of the selector cylinders is hard, there is no limit as to the fineness of the design that one wants to obtain. It is even possible to create a safety background with not only very fine lines, but also dots, which was previously impracticable. In the figure, the height of these raised areas is of course exaggerated.

Each selector cylinder 7 is associated in known manner with an inking device 8 comprising the inkwell proper and the picker rollers and the color distributor.

In the embodiment shown in the figure, the ratio between the diameters of the selection ink roller, respectively of the selection cylinders 7, of the collecting cylinder 3 and of the plate cylinder 1 is 1: 2: 3 and in this case , three plates are regularly distributed on the plate cylinder 1.

As the very fine sizes which represent the safety bottom are not deep, the pressure which must be applied to them by the collecting cylinder 3 must be lower than that applied by the conventional inking roller 4 to the deeper sizes representing the main drawing, this is why although the surface of the collecting cylinder 3 is a little elastic, there is no deformation of the smooth surface, so that the drawing can be transferred in perfect register. Likewise, between the selector cylinders 7 and the collecting cylinder 3 a low pressure is required, which is reduced practically to a simple contact, which avoids deformation of the very fine zones cut out on the selector cylinders.

In order to ensure this perfect register between the sectioned selector cylinders 7 and the printing plate, the procedure is as follows: one of the selector cylinders 7 not yet sectioned is mounted on the machine; then the printing plate is mounted on the plate cylinder 1 and inked and wiped; its image is then transferred, via the collecting cylinder 3, to the selector cylinder 7, from in such a way that the image of the plate remains printed on this cylinder which has not yet been cut. The selector cylinder 7 is then removed from the machine and the image of the plate is used to cut the surface by any suitable means. The image of the plate can, for example, serve as a basis for a photographic montage in the case where the cut is obtained by photomechanical bite. In the case where the cutting of the cylinder is obtained by means of a laser, the image of the plate serves as a basis for coordinates to be introduced into the laser machine so that the cutting perfectly follows the drawing in register with the plate. The same operation is naturally repeated for the other selector cylinders 7 representing the other colors.

Claims (1)

Intaglio printing machine for printing on paper or on a roll of security papers, in particular banknotes, comprising a plate cylinder with at least one engraved plate provided with sizes which represent the elements of a main design and of shallower and finer sizes representing the elements of a safety bottom, a printing cylinder, at least one inking roller for selecting an inking group cooperating directly with the plate to ink the sizes which represent the elements of the main drawing, a device for wiping the plate and preferably a pre-wiping device as well as another inking system for inking the sizes which represent the safety background in several colors with at least two colors, characterized in that the said inking system for inking the sizes, which represent the elements of the safety bottom, is constituted by a collecting cylinder (3) having a smooth and elastic surface cooperating with the engraved plate, this cylinder being situated, in the direction of rotation, in front of said selection ink roller (4) and comprising at its periphery at least two selector cylinders of different colors (7) which have reliefs corresponding to the zones colored of the security background, an inking device (8) being associated with each color selector cylinder (7).

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