DE10260124A1 - Security element for documents of value - Google Patents

Abstract

The invention relates to a transparent security element for valuable documents, comprising superimposed patterns on two opposing sides of a translucent carrier material. In a precise arrangement according to register, the two patterns complete each other to form a full image forming a code. If the positioning is not precise according to register, the code is illegible. The patterns consist of IR-absorbent material and can thus be read by a machine. A pattern can consist of IR-absorbent and IR-transparent partial patterns such that when observing transmitted light with normal light, a different transparent image can be recognised to that recognised when observing transmitted light with IR illumination.

Description

The invention relates to a security element for documents of value, which is a translucent carrier material with two patterns that only become apparent when viewed in transmitted light complete a visually recognizable, complete picture. The The invention further relates to a security document with a such security element.

Such security elements, also referred to as “see-through elements”, are known, for example, from US Pat EP 0 388 090 A1 are known and are used in particular for banknotes, checks, shares, tickets, admission tickets, identification papers and other paper documents of value, but also credit cards, check cards, identification cards and the like. The security documents described there have printed images on the front and back that complement each other to a complete image in transmitted light. Such security elements are difficult to imitate, since they can only be generated in register with simultaneous printing, ie with simultaneous printing on both document surfaces. The printed images can be designed as line patterns with identically spaced lines of identical width, which complement the full image in transmitted light. To further increase security, the printed images can be printed with invisible ink, which is absorbent, for example, for X-rays, so that the security element is visually inconspicuous and can be checked by machine.

In the DE 32 08 204 A1 It is also proposed to print a line pattern on the front and back of a document, but the line patterns are arranged in register so that they overlap each other exactly. An identical line pattern can then be seen in reflected light and transmitted light. In the case of forgeries that were not produced in simultaneous printing and in which the line patterns on the front and back of the document are not applied in exact register, moiré structures can be recognized in transmitted light due to the fineness of the lines. Alternatively, moiré structures can be intended and form a visually recognizable transparency authenticity feature through deliberate mutual displacement in partial areas.

Also in the EP 0 755 799 A1 It is proposed to apply a printed image, for example a number, in register form on both sides of the document, so that counterfeit falsifications can be identified when viewed through transmitted light. The printed image is preferably printed on the back of the document with an invisible ink, thereby preventing counterfeiting by copying. This invisible ink is preferably visible in the LV light to enable machine inspection.

In addition, it is in other Connection known, to imprint security documents, the special properties in the invisible spectral range possess machine-readable, visually not necessarily recognizable security features to create. For example, in patent CH 287332 Security document with a visually perceptible, for IR radiation described transparent color printing, which appears colored in reflected light, in transmission test in IR wavelength range however is white. A color copy of the document would also visually colored, but appear black in the IR transmission test and would be thus as a fake identifiable.

This thought is in the DE 26 54 208 B2 further developed where an IR transparent color print, which appears black in the visual spectral range, is covered with a black, IR absorbing color print or vice versa. The IR-absorbing color print can, for example, be a bar code, which, however, can only be recognized due to the black environment when viewed in the IR wavelength range. Depending on which color print is on the outside, a reflected light and / or transmitted light test is possible.

Also the JP-A-2167771 suggests the use of IR-transparent and IR-absorbing printing inks, which appear in the same color in the visual spectral range. The bars of a barcode are generated with the different colors, which then appear to the naked eye as a uniformly colored barcode. The different materials can then only be detected by machine.

Even the patent UK 1 534 403 discloses printed images, barcodes and the like which are printed with printing inks which appear in the same color in the visual spectral range and which have differently pronounced absorption properties in the IR spectral range. These printing inks can be spaced apart from one another or adjoining one another and in particular in an environment of the same color, which is printed with conventional color, so that the image is not perceptible visually, but can only be read by machine.

Object of the present invention is to create a see-through security element that is superior to conventional See-through elements an increased Has security and which visually and preferably also mechanically testable is. The object of the present invention is furthermore a To propose a security document with a correspondingly increased level of security.

This task is accomplished through a security element with the characteristics of the independent Claim 1 and equipped with such a security element Security document solved. Dependent on it claims are advantageous developments and refinements of the invention specified.

In contrast to the prior art, at which the printed images on opposite sides of the document either completely overlap in register ( DE 32 08 204 A1 . EP 0 755 799 A1 ) or to a complete picture ( EP 0 388 090 A1 ) supplement, the solution according to the invention provides that the two images complement one another to form a complete transparent image conveying specific information or a code, but at least partially overlap. The result of this is that the information is largely obscured even with a slight offset of the two patterns, since in this case also those subregions of one pattern that would be covered by the other pattern in the correct position contribute to the appearance of the see-through image. This makes it much easier to identify counterfeits, since if the pattern is not placed in the register, the information normally to be expected cannot be recognized when viewed through transmitted light. In other words, the one pattern acts as a filter for information conveyed by the other pattern, provided that the two patterns are positioned in register.

By now serving as a filter Pattern and the above lying pattern, which together in register arrangement information with the filter pattern, e.g. a code that conveys preferably consist of a material for radiation is absorbing in a defined, invisible wavelength range, can in addition to visual inspection too a mechanical transmission test of the see-through security element. It is sufficient if those sub-areas of the information-mediating pattern, in which the information-mediating pattern does not coincide with the Filter pattern covered, consist of the absorbent material, or that at least some these sections consist of absorbent material. Depending on, which sub-areas of the information-conveying pattern in the defined, invisible wavelength range are absorbent, different information can be obtained when viewing transmitted light with visible light on the one hand and with radiation in the invisible Wavelength range on the other hand produce.

A pattern or both patterns can be made be made of a color that is viewed in reflected light compared to the Ambient color is not or at least hardly visually recognizable.

The one described above is particularly pronounced Effect if the two patterns are line patterns, wherein the filter pattern is preferably a uniform line grid and the information-imparting pattern preferably a raster is made up of staggered lines. Of course you can also the filter pattern is a grid of staggered lines his. The two line grids are not in register visually very easily recognizable in transmitted light. If the distance between the lines and the line width of the two patterns are identical, placements that are not in register are all the more conspicuous.

The two patterns are preferred in simultaneous printing on opposite Sides of a translucent carrier material printed, i.e. on a translucent substrate so that the both patterns when viewed in transmitted light to a complete picture complete. The translucent day material can be, for example, the basic material of the value document itself, in the case of banknotes and other documents of value, for example Paper. The security element can also be used as a transfer element be formed, which is only in a further step on a Security document is applied. The security element can, however also be a security thread for storage in a value document.

It is not imperative that the two Patterns can be produced using the simultaneous printing process. If one accurate placement of the two patterns is guaranteed, the Patterns generated in any way and if necessary also be present together on one side of the carrier material.

A preferred embodiment the invention provides, for example, that the filter pattern by a partially demetallized metal layer is formed, wherein on the back side of the transfer carrier material for example, in the background printing an information-conveying Pattern is applied. The metallic filter pattern is for almost all wavelengths Completely absorbent, so the choice of material for the information-mediating Pattern is freely selectable in wide areas. Preferably at least Absorbing partial areas of the information-conveying pattern for radiation in the IR wavelength range. Sensors for the detection of IR-absorbing security elements in incident light and transmitted light are widespread, comparatively inexpensive and already in numerous value document checking devices available.

The invention is illustrated below by way of example of the accompanying drawings. Show it:

1 a banknote with a see-through security element;

2a an information-imparting pattern;

2 B a filter pattern;

2c a see-through element consisting of the patterns according to 2a and 2 B with visual transmitted light observation;

3a an IR-absorbing partial pattern of the information-conveying pattern 2a ;

3b an IR-transparent partial pattern of the information-conveying pattern according to 2a ;

3c a see-through element consisting of the patterns according to 2a and 2 B with IR transmitted light observation, whereby the informati ons mediating patterns 2a from IR-absorbing and IR-transparent partial patterns according to 3a . 3b composed.

4a an IR-absorbing partial pattern of the information-conveying pattern 2a ;

4b an IR-transparent partial pattern of the information-conveying pattern according to 2a ;

4c a see-through element consisting of the patterns according to 2a and 2 B with IR transmitted light observation, whereby the information-mediating pattern emerges 2a from IR-absorbing and IR-transparent partial patterns according to 4a . 4b composed.

1 shows an example of a banknote for all other documents of value mentioned at the beginning 1 with a see-through element 2 and a security thread 3 , periodically on the surface of the banknote in the manner of a window security thread 1 appears. The security thread 3 can in turn be formed in the same way as that below with regard to the see-through element 2 is described. That is, the security thread can also form a see-through security element according to the invention.

The see-through element 2 is formed by overlapping patterns, of which a first pattern is placed on the front of the banknote and a second pattern on the back of the banknote. The samples can be applied to the document using printing technology or a transfer process.

2a shows for example a first pattern 4 , which is hereinafter referred to as the "information-imparting pattern", and 2 B shows an associated second pattern 5 , which is referred to below as “filter pattern”. Both patterns can be recognizable in incident light. However, one of the patterns or both patterns can also be designed to be indistinguishable from the surrounding material in the visual spectral range or be present as background printing, so that they are not recognizable in incident light. It is only essential for the visual inspection that the materials according to the two samples 2a and 2 B are sufficiently opaque that they appear as dark areas in a bright environment when viewed in transmitted light.

In 2c is the appearance of the two patterns 4 and 5 formed see-through element 2 shown with normal light when viewed through transmitted light. This appearance is also referred to as a visual transparency 6 designated. One can see how the comparatively irregular information-conveying pattern 4 by overlaying the filter pattern 5 a regular, clear information conveying visual image 6 results. The information can form, for example, a machine-readable code. This information is out of the samples 4 and 5 cannot be derived in isolation. You would also not be reconstructable if the two patterns 4 and 5 would only be slightly shifted to each other. This would result in a very irregular pattern as a visual transparency.

The filter effect is explained below using an example area X. The sample area X _{4 of} the information-conveying pattern 4 has four upper lines and four lower lines that are partially offset from each other. The corresponding sample area X _{5 of} the filter pattern 5 has corresponding lines that are not staggered, but are continuous. The lines of the two patterns 4 and 5 have the same width and the distances between the lines correspond to the width of the lines. This means as far as the lines in the example area X _{4 of} the information-conveying pattern 4 opposite the lines of the filter pattern 5 are offset, they fill the intermediate areas or gaps between the lines of the filter pattern 5 out. Otherwise, the lines of the information-conveying pattern overlap 4 and the filter pattern 5 exactly. Accordingly, when viewed in transmitted light, the in 2c Example area marked with X ₆ in the see-through image 6 who has a visually clearly recognizable shape. Would be the sample area X _{4 of} the information-mediating pattern 4 only slightly or by a line width compared to the sample area X _{5 of} the filter pattern 5 the sample area X _{6 of} the visual see-through image would have shifted 6 a completely different shape. By changing the other areas of the information-mediating pattern 4 with corresponding areas of the filter pattern 5 superimpose according to a similar scheme, the overall result is an easily comprehensible appearance of the visual transparency 6 according to 2c ,

For an additional mechanical inspection of the see-through element 2 are to enable the patterns 4 and 5 Made from materials that are absorbent for radiation in the IR wavelength range. The appearance when viewed through transmitted light in the IR wavelength range then corresponds to the visual see-through image 6 and is subsequently referred to as the “IR transparency image 7 " designated. The IR transparency image 7 when using IR absorbing materials for the patterns 4 and 5 is in again 3c shown.

It is obvious that to obtain the IR transparency 7 according to 3c not necessarily all parts of the information-mediating pattern 4 must be made of an IR absorbent material if the filter pattern 5 itself also consists of IR-absorbing material. It is sufficient if only the partial areas of the information-conveying pattern 4 consist of an IR-absorbing material, which intermediate areas or gaps of the filter pattern 5 to complete. In 3a is accordingly an IR-absorbing partial pattern 4a of the information-mediating pattern 4 out 2a shown. In 3b is the corresponding IR transparent sub-pattern 4b of the infor mation-mediating pattern 4 out 2a shown. Both part patterns 4a . 4b together form the information-mediating pattern 4 , However, the actual information only conveys the IR-absorbing sub-pattern 4a , which the intermediate areas of the also IR-absorbing filter pattern 5 fills in, so that when the IR transmission is viewed, the IR transparency image 7 according to 3c results. The IR transparent partial pattern 4b however, completely overlaps with the filter pattern 5 ,

The regarding 3a and 3b The variant described has the advantage that, in addition to the IR transmitted light observation, that to the IR transmitted light image 7 according to 3c leads to a meaningful measurement result, since with IR reflected light only the partial pattern conveying the actual information 4a according to 3a is measured. This results in an identical image when viewed through transmitted light in the visual and in the IR spectral range, whereas no information is identifiable when viewed in reflected light in the visual spectral range, but in the IR spectral range, the information according to the partial pattern 4a ( 3a ) becomes recognizable.

A further preferred embodiment of the invention is in the 4a to 4c shown. In this case, the IR transparency 7 'differs from the visual transparency 6 , The information-mediating pattern 4 therefore has a different information content, depending on whether it is viewed in normal light or in IR light in transmitted light. This is achieved by using intermediate areas of the filter pattern 5 partly from IR-absorbing material and partly from IR-transparent material of the information-conveying pattern 4 be covered. 4a shows an IR-absorbing partial pattern 4a ' and 4b an IR-transparent partial pattern 4b ' , which together form the information-mediating pattern 4 according to 2a form. By comparison with the 3a and 3b it is immediately apparent that the sub-pattern carrying the actual IR information 4a ' out 4a towards the IR absorbing partial pattern 4a out 3a is reduced. The IR-transparent partial pattern is correspondingly more extensive 4b ' out 4b compared to the IR-transparent partial pattern 4b out 3b , Overlaid with the filter pattern 5 according to 2 B This results in an IR transparency image 7 'when viewed with IR transmitted light, as in 4c shown. The visual transparency 6 However, this does not change and corresponds accordingly 2c ,

In this embodiment variant, different transparency images 7 ', 6 are thus obtained on the one hand when viewed in the IR spectral range and on the other hand when viewed in normal light. In addition, the information according to the partial pattern is also in this embodiment variant 4a ' perceptible when viewed under IR light, whereas when viewed under reflected light under normal conditions, only the undefined pattern is perceptible 4 according to 2a is visible.

The regarding 4a to 4c The variant described is particularly suitable for different, batch-related IR coding of documents without the visual appearance being influenced thereby.

Claims (19)

Security element ( 2 ) for documents of value ( 1 ) comprising a translucent carrier material with a first and a second pattern ( 4 . 5 ), which only become a visually recognizable, complete see-through image when viewed in transmitted light ( 6 ), characterized in that the two patterns partially overlap. The security element according to claim 1, wherein the see-through image ( 6 ) forms a machine-readable code. A security element according to claim 1 or 2, wherein the first pattern ( 4 ) at least in individual areas where the second pattern is not ( 5 ) covered, consists of a material which is absorbing for radiation in a defined, invisible wavelength range, and the second pattern ( 5 ) is absorbing for this radiation. Security element according to claim 3, wherein the defined, invisible spectral range is in the IR spectral range. A security element according to claim 4, wherein the first pattern ( 4 ) from at least a first and a second partial pattern consisting of different materials ( 4a . 4b ; 4a ' . 4b ' ), whereby the material of the first partial pattern ( 4a ; 4a ' ) is transparent in the defined, invisible spectral range and the material of the second partial pattern ( 4b ; 4b ' ) is absorbent in the defined, invisible spectral range. Security element according to claim 5, wherein all subregions of the first pattern ( 4 ) in which the first pattern ( 4 ) not with the second pattern ( 5 ) covered, consist of the absorbent material. Security element according to claim 5, wherein only individual subregions of the first pattern ( 4 ) in which the first pattern ( 4 ) not with the second pattern ( 5 ) covered, consist of the absorbent material. Security element according to one of Claims 3 to 7, the partial regions made of absorbent material of the first pattern ( 4 ) form a machine-readable code. Security element according to one of claims 1 to 8, wherein at least the first pattern ( 4 ) is not or at least hardly visually recognizable in incident light. Security element according to one of claims 1 to 9, wherein the first pattern ( 4 ) consists of a grid of staggered lines. Security element according to one of claims 1 to 10, wherein the second pattern ( 5 ) consists of a line grid. The security element of claims 10 and 11, wherein the lines of the first and second patterns ( 4 . 5 ) have an identical line width and the distances between the lines correspond to the line width or an integer multiple of the line width. Security element according to one of claims 1 to 12, wherein the first and the second pattern ( 4 . 5 ) are present on opposite sides of the carrier material. Security element according to one of claims 1 to 13, which is a transfer element. Security element according to one of claims 1 to 13, wherein the security element ( 2 ) an integral part of a security document ( 1 ) forms and the carrier material is formed by the base material of the security document. Security element according to one of claims 1 to 13, which is a security thread. Security element according to one of claims 1 to 16, wherein at least one of the two patterns ( 4 . 5 ) is a print pattern. Security element according to one of claims 1 to 17, wherein at least one of the two patterns ( 4 . 5 ) is a partially demetallized metal layer. Security document ( 1 ) comprising a security element according to one of claims 1 to 18.