WO2011050956A1

WO2011050956A1 - Method and device for producing a continuous paper web having water marks

Info

Publication number: WO2011050956A1
Application number: PCT/EP2010/006579
Authority: WO
Inventors: Andreas Pretsch; Jürgen Ruck; André Gregarek; Bernd Oweger; Bernhard Wiedner; Manfred Heim; Helmut Müller
Original assignee: Giesecke & Devrient Gmbh
Priority date: 2009-11-02
Filing date: 2010-10-28
Publication date: 2011-05-05
Also published as: ES2430090T3; DE102009051637A1; EP2496504A1; EP2496504B1

Abstract

The invention relates to a method for producing a continuous paper web (10) for the production of security and value documents, comprising the following method steps: a) generating a continuous paper web (10) on a vat machine, wherein the paper web is divided into a plurality of equal paper sheets (12) extending transversely to the continuous longitudinal direction, and providing at least one paper sheet (12) per vat circumference of the vat with at least one water mark (20) for controlling further processing steps, wherein certain position deviations exists between the positions of the water marks (20) of the paper sheets, b) detecting the positions of two or more water marks (20) on the continuous paper web (10), c) determining mark positions having lesser position deviations than the position deviations of the detected water marks (20), d) generating colored identification marks (22) at certain mark positions of the paper web (10), and e) detecting the positions of the generated identification marks (22) and carrying out a further processing step using the detected positions of the identification marks (22).

Description

Method and apparatus for producing an endless paper web with watermark marks

The invention relates to a method for producing an endless paper web with watermark marks and to an apparatus for carrying out such a method.

When producing endless paper webs for security and valuable documents, watermark marks are often created as tax stamps for further manufacturing steps. Although the generation of watermark marks in the papermaking process is simple and inexpensive, the watermark marks are subject to a relatively large positional tolerance due to their production, which adversely affects the positional accuracy of the further processing steps.

Proceeding from this, the object of the invention is to provide a production method of the type mentioned above, in which subsequent processing steps can be carried out with greater accuracy.

This object is solved by the method and the device having the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

According to the invention, a generic method comprises the method steps: a) producing an endless paper web on a rotary screening machine, the paper web being subdivided into a plurality of identical paper sheets extending transversely to the endless longitudinal direction, and

CONFIRMATION OPH Providing at least one paper sheet per screen circumference of the round screen with at least one watermark for the control of further processing steps, wherein between the positions of the watermark marks of the paper sheet certain positional deviations exist,

Detecting the positions of two or more watermark marks on the endless paper web,

Determining marker positions with position deviations less than the position deviations of the detected watermark marks,

Producing colored indicia marks at the particular label positions of the web, and

Detecting the positions of the generated flags and performing another processing step using the detected positions of the flags.

According to the invention, it is sufficient to provide a paper sheet per screen circumference of the round screen of the paper machine with a watermark. However, it is of course possible per screen circumference and several or even all paper sheets are provided with watermark marks.

The identification marks can be generated in step d) by a touching method. In an advantageous variant of the invention, however, the identification marks are generated in step d) with a non-contact method. In particular, it has proved useful to tion marks in step d) in the inkjet process, wherein due to the finite time of flight of the ink droplets from the print head to the paper web advantageously an ink flight time compensation is performed. A particular advantage of inkjet-applied markers is that there is no need to extract smoke or snippets as would be necessary with a laser-cut mark. In addition, inkjet printers are very compact devices that can be easily integrated into existing equipment. In general, unlike using a hole as a control mark, a colored tag, after cross-cutting, can not hinder the stacking of the individual sheets of paper or cause the holes to get caught.

In a further advantageous non-contact method, the identification marks are generated in step d) by laser marking. For this purpose, in a preferred embodiment of the invention, laser-sensitive feature substances can already be introduced into the paper in step a). Alternatively or additionally, laser-sensitive feature substances can also be applied to the paper web after papermaking. As laser-sensitive feature substances, a large number of substances known per se to the person skilled in the art, such as TiO ₂ , soot particles or infrared absorbers, come into consideration. By laser application, the laser-sensitive feature substances are locally modified, for example colored and preferably blackened, and thereby form a machine-detectable identification mark.

In a preferred embodiment, identification marks are simultaneously generated on the front and back of the paper web in step d) by laser marking. In another likewise advantageous variant of the invention, the identification marks are produced in step d) with an arbitrary printing method, in particular in rotary flexographic printing, rotary offset printing, rotary screen printing or intaglio printing.

In all variants, dark or even black identification marks are advantageously generated in step d), which can be recognized particularly easily and reliably by sensors. The colored identification marks can also be produced with dyes which are not visible in the visible spectral range or only visible after excitation, such as IR or UV dyes or else luminescent dyes.

In a preferred variant of the invention, the positions of the generated identification marks are detected in step e) in a further processing step, and the paper web is provided with at least one security feature in each of the paper sheets using the detected positions of the identification marks.

In particular, in step e) the current length of a paper sheet is determined in a further processing step el) from the detected positions of the identification marks, and becomes

e2) a film with applied to the paper web security features according to the current arc length stretched and applied to the paper web.

Alternatively or additionally, it is advantageous in step e) in a further processing step fl) determines from the detected positions of the identification marks the current length of a paper sheet and compared with a predetermined desired length, and is

f2) the position of security features to be generated on the paper web by means of a non - contact method on the basis of

Deviation of the current arc length from the nominal length corrected.

The further processing step can not only consist in providing the paper sheets with security features using the detected positions of the tags. It is also within the scope of the invention, for example, if the positions of the identification marks form the basis for the generation of further position marks with even smaller position deviations. In such an inventive variant are advantageously in step e) in a further processing step

gl) of the positions of two or more tags on the endless web of paper,

g2) mark positions are determined with position deviations smaller than the position deviations of the detected marking marks,

g3) further position marks are generated at the determined mark positions of the paper web, and

g4), the positions of the generated position marks are detected and a further processing step is performed using the detected positions of the position marks.

In this variant of the invention, the other position markers can be generated with the same tool together with other security features with particular advantage. The position tags and security features then have a fixed reference and subsequent applications can be adjusted more precisely. Position deviations in the tool can also be compensated by a subsequent flexible application. These advantages are illustrated below using the example of the simultaneous printing of identification marks and a printing feature.

The still further processing step can then be, for example, in the detection of the positions of the position marks for determining the actual length of the paper sheet and the application of a film corresponding to the above step e2) or the correction of the position of non-contact safety features corresponding to the above-mentioned step f2 ) consist.

The position markers, like the markers, can be produced in color, in particular black, with preferably non-contact methods or printing methods being used. However, the position marks can also be formed by punch marks and in this case, for example, be generated by a rotary punch or by a laser cutter. The invention also includes an apparatus for carrying out the described method, with

a transport device for transporting the endless paper web, a first detection device for detecting the positions of two or more watermark marks on the endless paper web, an evaluation device for determining the mark positions with smaller position deviations,

an identification device for generating the colored identification marks at the determined brand positions of the paper web, second detection means for detecting the positions of generated flags and

a processing device for performing a further processing step using the detected positions of the identification marks.

The marking device preferably comprises an inkjet printer or a laser writer. The laser source is advantageously an infrared laser in the wavelength range from 0.8 μm to 3 μm, in particular a Nd: Y AG laser or a Nd: YV0 ₄ laser, or else a CC * 2 laser with a wavelength of 10, 6 μιη used.

The processing device advantageously comprises a device for stretching and applying a film to the paper web and / or a device for non-contact application of a security feature.

In principle, it is always possible to measure the position of a security feature of an application in each use online, for example, by a camera system, and to control a follow-up application with a flexible tool to the measured position.

In the case of first producing inkjet marks and subsequently laser marks or stamped marks, it may be provided that the inkjet marks are cut out by the laser marks or the stamped mark. In this way, the number of marks present on the sheets that could interfere with successor applications is reduced. The described advantages can also be realized in hybrid designs, in which the inkjet marks can also be printed only after film filming. Furthermore, the principles described can also be used advantageously in the production of pure polymer banknotes since, although there are no watermark marks, the problem of the different influence of a deviating arc length on methods with rigid or flexible tools also exists.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the representation of which a representation in terms of scale and proportions has been dispensed with in order to increase the clarity. The various embodiments are not limited to use in the specific form described, but can also be combined with each other.

Show it:

1 shows an endless paper web which is subdivided into a plurality of identical paper sheets extending transversely to the endless longitudinal direction,

1 with two security elements applied in separate application steps, FIG.

3 a paper sheet as in FIG. 2, in which the current sheet deviates from the desired sheet length, and Fig. 4 shows a paper sheet as in Fig. 2 according to an embodiment of the invention, in which the current arc length deviates from the desired arc length and the laser holes are generated at corrected positions.

The invention will now be explained using the example of an endless paper web for the production of banknotes. 1 shows an endless paper web 10 which is subdivided into a plurality of identical paper sheets 12 _n- i, 12 _n , 12 _n + i extending transversely to the endless longitudinal direction 18. The boundary lines 14 of the individual paper sheets 12 are imaginary lines, which are shown in FIG. 1 for illustration, but are not present on the paper web as visible marking lines.

During the production of the paper web 10, at least one watermark 20 was introduced in each paper sheet 12 for the control of further processing steps. The introduction of such watermark marks 20 is very easy and inexpensive possible in papermaking. However, the watermark marks 20 are due to the production of a relatively large position tolerance, so that between the positions of the watermark marks 20 same paper sheet 12 certain positional deviations exist.

For the purpose of illustration, the watermark marks 20 with their distance Xk from the boundary line 14 of the associated paper sheet 12k for k = n, n + 1 are shown schematically in FIG. The mentioned positional tolerance of the watermark marks 20 then means that the distance values Xn-i, n, Xn + i, etc. have a relatively large fluctuation. In order to improve the accuracy of subsequent application steps against the use of the watermark marks 20 as control marks, the positions of two or more watermark marks 20 on the endless paper web 10 are detected and mark positions are calculated which have lower position deviations than the watermark marks 20.

Such a determination of brand positions with smaller position deviations can be done, for example, by averaging the acquired positions. Since banknote paper is usually made in a rotary screen technique, the position of a watermark 20 is repeated approximately with each screen circumference. Therefore, it is advantageous to averaged over a multiple of watermark marks 20 per screen circumference to determine more accurate label positions. In the exemplary embodiment, about m watermark marks 20 come to a screen circumference and it is averaged over three sieve circumferences. For the averaging, a shift register is advantageously used in which the position of a newly acquired watermark mark x _n replaces the oldest detected position x _n -3m. By

3M-1

y _n = Σ ni

i = 0 3m are then given brand positions y _n with position deviations less than the position deviations of the watermark marks 20, since their random positional fluctuations are found out in the calculation.

At the brand positions y _n calculated in this way, colored identification marks 22, which are used as control marks for the further application steps, are now generated with a non-contact method, and which improve the position accuracy of the subsequent application steps due to their lower position deviations.

The inkjet method has proven particularly suitable for producing such colored identification marks 22. An applied by inkjet printer, usually black marking mark 22 can be very well detected by a machine. In addition, inkjet printers have a very compact design and can therefore be easily integrated into existing systems. When applying the identification marks 22 by inkjet process, no extraction of smoke or accumulating snippets is required. In addition, an applied colored marking mark, unlike a through opening, after the cross cutting can not hinder the stacking of the paper sheets 12 or lead to a hooking of the through holes.

Since the print head of an inkjet printer has a certain distance from the paper web 10, due to the rapid movement of the paper web 10, the time of flight of the ink droplets is taken into account as a function of the web speed during printing.

In another embodiment of the invention, the colored identification marks 22 are formed by a laser mark. For this purpose, for example, laser-sensitive feature substances can already be introduced into the paper during papermaking, or laser-sensitive feature substances can be applied to the paper web after papermaking. Suitable laser-sensitive feature substances are, for example, T1O2, soot particles or infrared absorbers. As a result of the laser application, the laser-sensitive feature substances are locally modified, for example colored or blackened. A particular advantage of this variant of the invention is that the laser radiation can reach through the paper web, so that identification marks can be generated simultaneously on the front and back of the paper web in one operation. The identification marks on the front and back are perfectly matched to each other and allow a highly accurate alignment of subsequent processing steps, both on the marks of the front and on the marks on the back.

In addition to the mentioned non-contact methods for applying the identification marks 22, other printing methods, such as rotary flexographic printing, rotary offset printing or rotary screen printing, are generally also considered.

In an advantageous variant of the invention, the imprinting of the identification marks 22 takes place in one operation with the imprinting of a printing feature. In this case, the tags 22 may be integrated into the print tool so that they are perfectly matched to the print image of the print feature. For example, an identification mark can be integrated in the rotary screen in the printing screen. The subsequent applications controlled on the identification mark generated during the printing step then have a very good registration with the print images of the printing step.

Generally, in subsequent applications, the positions of the generated indicia marks 22 are advantageously detected, and the paper web 10 is provided with at least one security feature using the detected positions of the indicia marks in each of the paperboards. In the control of the application machines, a distinction is made between machines with rigid tools, such as in screen printing or a rotary die, and machines with flexible tools, such as a laser cutting machine, since each has different consequences in a deviation of the current sheet length of a paper sheet result from its nominal arc length. These differences and their treatment in the context of the present invention will now be explained with reference to FIGS. 2 to 4. 2 shows first a single sheet of paper 12 of the paper web 10 with watermark 20 and marking mark 22. Each sheet of paper 12 carries a plurality of individual benefits 16, which correspond to the later cut banknotes in the embodiment. The nominal length of a single sheet of paper 12 is denoted by Ls.

The individual benefits 16 are provided after papermaking in the further processing of the paper web 10 in two separate application steps with two security features 30, 32, which are aligned in the target image and complement each other to form an overall feature 34. This is shown schematically in Fig. 2 by the addition of the two semicircular disks 30, 32 to a circular disk 34.

The first security feature 30 is a security feature applied with a rigid tool, in the exemplary embodiment a film feature 30 present on an endless film strip, which is applied to the paper sheet 12 together with the film strip. The second security feature 32 represents a security feature produced with a flexible tool, which in the exemplary embodiment is formed by a through hole 32 cut in the cartridge by means of laser radiation. Pierbogen 12 is formed. If the film features 30 and the laser holes 32 have their desired positions shown in FIG. 2, they complement each other without any offset to the overall feature 34, such as the circular disks shown by way of example in FIG. 2.

On the other hand, if the current sheet length Li of a paper sheet 12 deviates from its desired sheet length L _s , as illustrated in FIG. 3, the tools run on machines with rigid tools with a changed peripheral speed. Since a film strip to be applied can only be stretched but not shrunk, the repeat of the features on the film strip is selected to be slightly shorter than the target sheet length Ls and the film strip is stretched to the respective current sheet length Li of the paper sheet 12 when applied to the paper web , However, as a result of the expansion, the absolute position of the film features 30, based on the tag 22, and thus also the positions of the film features 30 within the individual bumps 16, deviates from the desired desired positions, as in FIG. 3 due to the offset of the left semicircular disks illustrated. In machines with flexible tools, such as the aforementioned laser cutting machine, there is no automatic interaction between the current sheet length Li and the position of the laser holes 32 generated. As a result, the absolute position of the laser holes 32 within the individual bumps 16 im also corresponds to the sheet lengths Li deviating from the nominal length Essentially their position at the desired length Ls, as illustrated in Fig. 3 by the missing offset of the right semicircular discs.

Since the positions of the film features 30 and the laser holes 32 thus react differently to a changed current sheet length Li, it can come to deviations in the relative positioning of the two features. As can be seen in FIG. 3, the two security features 30, 32 then no longer complement each other in the desired manner to the overall feature 34, as can be seen in particular in the lowest utility line with the greatest distance to the identification mark 22, where the relative deviation of the two Security features 30, 32 are the largest.

In cases where good registration of the two security features 30, 32 relative to each other is more important than the location of the overall feature 34 within the single utility 16, in accordance with the invention, the location of the security features 32 created with flexible tools will be at the location of the security features created with rigid tools 30 adjusted.

In the exemplary embodiment, for the application of the film features 30, the positions of the marking marks 22 are detected and the current length Li of a paper sheet 12 is calculated from the detected positions of the marking marks 22. Then a film strip is stretched with the applied to the paper web 10 film features 30 corresponding to the current sheet length Li and applied to the paper web 10.

To generate the laser holes 32, the positions of the identification marks 22 are also detected and from the detected positions of the marking marks 22 the current length Li of the paper sheet 12 is calculated. The actual length Li of the paper sheet is compared with the predetermined target length L _s , and the position of the laser holes 32 is corrected based on the deviation of the actual sheet length Li from the target length Ls. The laser holes 32 are then generated at the corrected positions and not at the predetermined positions based on the target arc length L _s . Was previously worked with a rigid tool, can with a flexible tool and any existing in the rigid tool position deviations are compensated.

This results in a very good registration of the two security features 30, 32 relative to one another, even if the position of the overall feature 34 varies within the individual bumps 16, as illustrated in FIG. 4. The visual impression of the overall features 34 is clearly superior to the visual impression without correction of the laser holes 32 of FIG. 3 in the inventive design of FIG.

The positions of the laser holes 32 can be corrected particularly well, if the percentage deviation of the arc length is used as a basis for calculation. The corrected distance di two laser holes 32 is then

where ds denotes the nominal distance between two laser holes 32. Accordingly, the distance a! the marking mark 22 to the first laser hole ai = as * Li / Ls, with the desired distance as between mark and first laser hole, and the distance zi of the last laser hole to the identification mark 22 of the subsequent paper sheet zi = zs * Li / Ls, with the desired distance zs between the last laser hole and the next mark. LIST OF REFERENCE NUMBERS

10 paper web

12 paper sheets

14 boundary lines

16 individual benefits

18 longitudinal direction

20 watermark mark

22 identification marks

30, 32 security features

34 overall feature

112 optically variable color pigments

Claims

Patent claims

A method of producing an endless paper web for the production of security and value documents, comprising the steps of: a) producing an endless paper web on a rotary screening machine, wherein the paper web is subdivided into a plurality of identical paper sheets extending transversely to the endless longitudinal direction, and providing at least one paper sheet per screen circumference of the round screen with at least one watermark for the control of others

Processing steps wherein there are some positional deviations between the positions of the watermark marks, b) detecting positions of two or more watermark marks on the endless paper web, c) determining marker positions with smaller positional deviations than the positional deviations of the detected watermark marks, d) generating colored indicia marks at the designated mark positions of the web, and e) detecting the positions of the generated indicia marks and performing another processing step using the detected positions of the indicia marks.

2. The method according to claim 1, characterized in that the identification marks are generated in step d) with a non-contact method.

3. The method according to claim 2, characterized in that the identification marks are generated in step d) in the inkjet process, preferably in that an ink flight time compensation is performed.

4. The method according to claim 2, characterized in that the

Identification marks in step d) are generated by laser marking, wherein laser-sensitive feature substances are preferably introduced into the paper in step a) or laser-sensitive feature substances are applied to the paper web after papermaking.

5. The method according to claim 4, characterized in that in step d) by laser marking simultaneously on the front and back of the paper web identification marks are generated.

6. The method according to claim 1, characterized in that the

Identification marks in step d) with a printing process, in particular in rotary flexographic printing, rotary offset printing or rotary screen printing, are generated.

7. The method according to at least one of claims 1 to 6, characterized in that in step d) dark, in particular black identification marks are generated.

8. The method according to at least one of claims 1 to 7, characterized in that in step e) in a further processing step, the positions of the generated identification marks are detected and the paper web using the detected positions of the identification marks with at least one security feature in each of Paper sheet is provided.

9. The method according to at least one of claims 1 to 8, characterized in that in step e) in a further processing step el) from the detected positions of the identification marks the current length of a paper sheet is determined, and e2) a film to be applied to the paper web Security features stretched according to the current arc length and on the

Paper web is applied.

10. The method according to at least one of claims 1 to 9, characterized in that step e) in a further processing step fl) from the detected positions of the identification marks the current length of a paper sheet is determined and compared with a predetermined nominal length, and f2) the position is corrected by means of a non-contact method on the paper web to be generated security features based on the deviation of the current arc length of the desired length.

11. The method according to at least one of claims 1 to 7, characterized in that in step e) in a further processing step gl) the positions of two or more identification marks are detected on the endless paper web,

Marker positions are determined with position deviations less than the positional deviations of the detected identification marks, more position marks are generated at the specific brand positions of the paper web, and the positions of the generated position marks are detected and yet another processing step is performed using the detected positions of the position marks.

12. An apparatus for carrying out the method according to any one of claims 1 to 11, comprising a transport device for transporting the endless paper web, a first detection means for detecting the positions of two or more watermark marks on the endless paper web, an evaluation device for determining the brand positions with lower position deviations . a marking device for generating the colored marking marks at the determined mark positions of the paper web, a second detecting device for detecting the positions of generated marking marks and a processing device for performing a further processing step using the detected positions of the marking marks.

13. The apparatus according to claim 12, characterized in that the marking device comprises an inkjet printer or a laser writer.

14. The apparatus of claim 12 or 13, characterized in that the processing device comprises a device for stretching and applying a film to the paper web.

15. The device according to at least one of claims 12 to 14, characterized in that the processing device comprises a device for non-contact application of a security feature.