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(11) | EP 1 602 483 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Intaglio printing machine and process |
| (57) The printing machine for sheets (2) of documents, such as securities, bank-notes,
checks, ID, passports and other similar documents, comprises at least a plate cylinder
(5) supporting printing plates (6,7,8) with engravings, a first inking unit for inking
said plates, an impression cylinder (3) supporting said sheets (2) and cooperating
with said plate cylinder (5), and a wiping device (20) for wiping the ink on the surface
of said plates (6,7,8) outside the engravings. It comprises an inking unit (21) placed
downstream of the wiping device (20) in the sense of displacement of the sheets (2)
for an additional deposition of ink on the wiped surface of the plates (6,7,8). |
[0002] The present invention also concerns an inking process used in the printing machine of the present invention.
[0003] Printing machines, in particular intaglio printing machines, are known per se in the art. For example, US patent 4,516,496, the content of which is incorporated by reference in the present application, discloses an intaglio printing machine. This known machine comprises a plate carrier cylinder cooperating with an impression cylinder. The plate cylinder carries a plurality of etched plates having engraved on their surface drawings to be printed on a support, such as paper, carried by the impression cylinder. The plates are inked either directly by a plurality of selective inking cylinders, or indirectly by a collector cylinder, said collector cylinder having being inked by selective inking cylinders. Once the inking operation is terminated, the plate cylinder undergoes a wiping operation carried out by a wiping cylinder, which cleans the planium (the smooth surface of the printing plate outside the engraved or etched cuts) and forcing the ink into the cuts.
[0004] Although the mentioned printing technology is well known in the art, there is always a trend to improve the known processes and products. In particular in the field of securities (i.e. bank-notes, checks, ID, passports, bonds and other similar items) there is a constant search to improve the products in order to provide documents that are not easy, if not impossible, to copy with modern devices such as photocopiers and scanners.
[0005] Many security elements such as holograms, latent images, optically variable elements are known in the art and used in the present field. However, some of these elements impose the buying of expensive equipments and material, and also use complicated technologies not always easy to put into practice.
[0007] More specifically, an object of the invention is to propose a printing machine making it possible to increase the possibilities for printing security papers, whether web fed or sheet fed, in a manner such as to improve the security factor thereof and to diversify possibilities for using different printing techniques and different colors. The forgery of security papers is thus rendered more complex and the resources needing to be employed by persons intending to forge security papers become more and more substantial.
[0008] It is another aim of the present invention is to provide a printing machine which is modular.
[0009] A further aim of the invention is to provide a printing machine, which is able to print documents with additional security elements.
[0011] An advantage of the invention is the fact that it is a modular unit that can be added in existing printing machines, therefore adding a printing element without the need for changing the entire machine.
[0012] Another advantage of the machine is the fact that it adds another printing possibility with a different technology therefore making the printed matter/document more difficult to copy and counterfeit.
[0013] The present invention will be best understood by the description of embodiments thereof and the figures relating thereto, in which
Figure 1 shows a first configuration of a printing machine according to the invention and
Figure 2 shows a second configuration of a machine according to the present invention.
Figures 3a to 3c show different embodiments of an additional inking unit according to the invention.
Figure 4 shows a block diagram of a process according to the invention.
[0014] In the configuration of figure 1, the machine comprises a transfer cylinder 1 for delivering successive sheets 2 to an impression cylinder 3 comprising gripping means located in pits 4 of the cylinder 3, as is known in the art of printing machines. The impression cylinder 3 cooperates with a plate cylinder 5, which carries engraved or etched plates, 6, 7, 8. The plates 6, 7, 8 of the plate cylinder 5 are inked by a smooth-surfaced collector cylinder 9 which is inked by several conventional selective inking rollers 10, 11, 12, 13 and 14, each inking the collector cylinder with a different color of ink supplied by respective color inking systems 15, 16, 17, 18 and 19. As is known in the art of printing, for example from US 4,516,496 incorporated herein by reference, the surface of the selective inking rollers is divided into several reliefs areas having contours corresponding to those of the surfaces to be printed for a precise inking of the plates.
[0015] The machine also comprises a wiping device 20, in the shape of a wiping cylinder, for cleaning the planium of the plates, i.e. the smooth surface of the printing plates outside the engraved or etched cuts, and forcing the ink into the cuts of the plates 6, 7, 8.
[0016] Once the wiping has been carried out, i.e. after the wiping device 20 in the sense of displacement of the sheets, the plates are then inked by a further inking unit 21, placed after the wiping device 20 in the sense of rotation of the plate cylinder 5. Said additional inking is preferably, but not limited thereto, carried out on the zones of the plates which have been wiped by the wiping device 20.
[0017] Accordingly, the inking operation per se comprises an inking step with the collector cylinder 9 and then a wiping step with the wiping device 20 and an additional inking step with the second inking unit on the surface of the plates, this additional inking step being carried out after the wiping step.
[0018] In another configuration represented in figure 2, the machine comprises a transfer cylinder 1 for delivering successive sheets 2 to an impression cylinder 3 comprising gripping means located in pits 4 of the cylinder 3, as is known in the art. The impression cylinder 3 cooperates with a plate cylinder 5, which carries engraved or etched plates, 6, 7, 8. The plates 6, 7, 8 of the plate cylinder 5 are inked by a smooth-surfaced collector cylinder 22 which is inked by several conventional selective inking rollers 23, 24 and 25, each inking the collector cylinder with a different color of ink supplied by respective color inking systems 26, 27 and 28. As is known in the art of printing, for example from US 4,516,496 incorporated herein by reference, the surface of the selective inking rollers is divided into several reliefs areas having contours corresponding to those of the surfaces to be printed for a precise inking of the plates.
[0019] In addition, the machine comprises a selective inking roller 29 that directly inks the plates, which is placed after said ink rollers 23 to 25 in the sense of displacement of the sheets. The selective inking roller 29 is preferably similar to the ink rollers 23 to 25 with its surface cut into reliefs areas having contours corresponding the engravings in the plates to be inked and its own inking system 30.
[0020] The machine in this configuration also comprises a wiping device 20, in the shape of a wiping cylinder, for cleaning the planium of the plates 6, 7, 8, i.e. the smooth surface of the printing plates outside the engraved or etched cuts, and forcing the ink into the cuts of the plates 6, 7, 8.
[0021] After the wiping device 20 in the sense of rotation of the plate cylinder 5, an additional inking unit 21 is placed to carry out a further inking step of the plates 6, 7, 8, said additional inking step being carried out, preferably but not limited thereto, on the zones of the plates which have been wiped by the wiping device 20.
[0022] Accordingly, the inking operation per se comprises an inking step with the collector cylinder 9 and then with the selective inking roller 29, followed by a wiping step with the wiping device 20 and an additional inking step on the surface of the wiped plates 6, 7 and 8 with the additional inking unit 21.
[0023] The additional inking unit 21 of the configuration shown in figure 1, or the second inking unit 21 of the configuration shown in figure 2, can be any type of surface inking device which is able to ink a surface of the plate. It can be made of a selective inking roller similar to the ink rollers 10 to 14 or 23 to 25 and 29, with a surface cut into reliefs forming the shape to be inked on the surface, said roller being inked by successive rolls as shown in the figures or equivalent inking devices.
[0024] For example, the additional inking unit 21 can be a silk-screen printing unit as shown in figure 3a, or an indirect printing unit as shown in figure 3b or an indirect collecting printing unit as shown in figure 3c.
[0025] As is well known in the art of printing machines, a silk-screen printing unit comprises a silk-screen cylinder in which a doctor blade is placed to push the ink through the silk-screen. An example of a silk-screen printing machine is given in US 6,109,172 the content of which is incorporated by reference in the present application in respect to this technology. This inking unit hence comprises a screen-cylinder 35 with a cam 36 on its axis rotating with it acting on a lever in the shape of an angle bracket 37. The vertex of the angle bracket 37 is articulated on a fixed point 38 and the other end of the lever is fastened to a squeegee 39 as disclosed and explained in said US 6,109,172 patent. Accordingly, ink is deposited on the surface of cylinder 5 by means of this silk-screen cylinder in a known manner.
[0026] In the configuration of figure 3b, the inking unit 21 comprises a blanket cylinder 40 which is inked by a plate cylinder 41 and selective inking roller 42 with an inking system 43.
[0027] In the configuration of figure 3C, the inking unit comprises a collector inking cylinder 44 which is inked by two selective inking rollers 45, 46 which are, themselves, inked by respective color inking systems 47 and 18. In this case, each color inking system 47 and 48 may ink rollers 45 and 46 with a different color. Therefore, in this configuration, the additional inking unit is able to add two more colors on the plate cylinder 5.
1. An intaglio printing machine for sheets (2) of documents, such as securities, bank-notes,
checks, ID, passports and other similar documents, said machine comprising at least
a plate cylinder (5) supporting printing plates (6,7,8) with engravings, a first inking
unit for inking said plates, an impression cylinder (3) supporting said sheets (2)
and cooperating with said plate cylinder (5), and a wiping device (20) for wiping
the ink on the surface of said plates (6,7,8) outside the engravings, wherein the
machine further comprises a further inking unit (21) placed downstream of the wiping
device (20) in the sense of displacement of the sheets (2) for an additional deposition
of ink on the wiped surface of the plates (6, 7, 8) .
2. The printing machine as claimed in claim 1, wherein the further inking unit (21)
comprises a selective inking roller.
3. The printing machine as claimed in claim 1 or 2, wherein the first inking unit comprises
at least one selective inking roller (10,11,12,13,14) for inking a collector cylinder
(9), said collector cylinder (9) inking the plates (6,7,8).
4. The printing machine as claimed in claim 1, 2 or 3, wherein the first inking unit
comprises at least one selective inking roller (29) for a direct inking of the plates
(6,7,8).
5. The printing machine as claimed in claim 1, wherein the further inking unit is a
silkscreen printing unit (35,36,37,38,39).
6. The printing machine as claimed in one of claims 1 to 4, wherein the further inking
unit is a multicolor inking unit (44,45,46,47,48).
6. An inking process for the inking of printing plates with engravings, such as intaglio
printing plates, comprising the following steps:
-) first inking of the engravings of the plates with first inking means;
-) wiping of the plates with a wiping device;
-) additional inking of the plates after said wiping step.
7. A process as defined in claim 6, wherein the first inking step includes indirect
inking of the plates.
8. A process as defined in claim 7, wherein the first inkingstep includes direct inking
of the plates.
9. A process as defined in one of claims 6 to 8, wherein the additional inking step
is carried out on the wiped surface of the plates.
10. A process as defined in claim 9, wherein the additional inking step is a direct inking,
or an indirect inking, or a silk-screen inking.