DE102019122586B4 - Microstructured transparent security element - Google Patents

Abstract

A security element (1) is described which has an upper side (4) and an underside (5) and is designed for use for a security document (20). The security element (1) comprises a window area (6) which is at least partially transparent to visible light, the window area comprising structural elements (2) with dimensions of less than 200 micrometers (200 μm), which are arranged and designed so that only when a Illumination of the underside (5) by means of a display (10) a colored image on the upper side (4) is visible.

Description

The invention relates to a security element for use in a security document and a method for producing a security element for use in a security document. The invention also relates to a security document, a method for producing a security document and a method for checking the authenticity of a security document.

background

To increase the protection against forgery of security documents, in particular also documents of value, different features and methods are used which make replication or alienation difficult or prevent. This applies in particular to the representation or portrait of a document owner. Laser inscription has proven to be advantageous because this method allows personalization within the laminated composite. The laser inscription usually creates a grayscale image.

From the document WO 2011/124774 A1 a method is known in which a colored portrait is generated by laser inscription in that a colored preprint consisting of alternating primary or basic colors R, G, B, (C, M, Y) and additional white areas is specifically blackened and locally using pulsed laser radiation is provided with grayscale, so that the remaining non-blackened color areas give a colored impression. As the laser effect blackens the affected areas, a light, neutral-colored pre-print with white spaces is necessary so that the overall picture does not become too dark. This is stated in the document US 2013/0328995 A1 achieved in that between the colored areas, in particular between individual pixels, transparent regions are arranged, which appear white due to the layer below. A disadvantage of the variants mentioned is the low color saturation, which results from the required white areas and / or the relatively light preprint.

As described above, the known methods require a light preprint with a white component, which prevents good color saturation and considerably limits the color space that can be achieved, so that the results do not achieve the quality of a printed representation. The colored preprint and the laser-blackened areas are located as two-dimensional levels in the material. A separate examination of the laser marking and the pre-printed form is not possible. Therefore, without further aids, it is difficult or impossible to distinguish a pre-print personalized by laser marking from a completely printed portrait, which, printed with the same layout, is located under a transparent cover sheet.

In the document DE 10 2012 109 064 A1 describes the laser processing of a light control film or lamella film, whereby a personalized element, for example a portrait, can be introduced into a window of a value or security document. Light control foils or lamellar foils have a large number of parallel grooves that are formed in light-absorbing material, so that, depending on the orientation of the grooves, the distance and the geometry, the foils achieve maximum light transmission at a predetermined angle or image fade-out or image darkening at certain angles . At a first viewing angle, the film appears essentially transparent and at a second viewing angle, it appears dark.

In the document DE 10 2011 084 819 A1 A method is disclosed for verifying a security document with a stored second pattern using a display device, a first pattern being displayed on the display surface for verification. In the document DE 10 2011 084 818 A1 a method for verifying a security document is described, wherein the security document comprises a visual barrier and for verification at least two images of the security document in front of the display device, on the display surface of which a graphic representation is displayed, are recorded for at least two different viewing geometry directions.

The document US 2011/0187747 A1 describes in connection with hidden pictures a method in which a first picture and a second picture are obtained, wherein the first and the second picture together provide a hidden picture and a decoder, so that a hidden picture is decoded by the decoder when the first Image and the second image are superimposed in at least one decoding position. The first image is printed on a translucent substrate to create a printed substrate. The second image is displayed on an electronic display and the printed substrate is overlaid relative to the display at a decoding position to decode the hidden image.

In the document US 2018/0304668 A1 discloses a security article with a disclosure screen and a combined image and a set with a security article and another object. The security article contains the disclosure screen or combined image and the object contains or constitutes the other of the Revelation video and the combined image. The combined image contains several overlapping images. The combined image contains a periodic change of overlapping picture elements in a first direction. The disclosure screen includes a masking screen that periodically alternates with a non-masking screen in a second direction. The size of the non-masking screen elements in the second direction is larger than the size in the first direction of at least one element of overlapping images, the disclosure screen allowing different disclosed images by moving the disclosure screen relative to the combined image and / or by changing the viewing angle to observe.

The following definitions are from the document EP 2 738 624 B1 been taken over. As already defined there, in connection with the present invention, a security element is understood to be a structural unit which comprises at least one security feature. Security elements serve to secure security documents, which also include documents of value, against forgery or copying. A security feature can be an independent structural unit that can be connected, for example glued, to a security document, which can also be a value document. However, it can also be an integral part of a security document. A security feature is a structure that can only be produced or reproduced in an unauthorized manner with increased effort compared to simple copying or not at all.

Security documents typically have a substrate, a printing layer and optionally a transparent cover layer. A substrate is a support structure on which the printing layer with information, images, patterns and the like is applied. All conventional materials based on paper and / or plastic can be used as materials for a substrate, among other things. Examples of security documents are identity cards, passports, driver's licenses, ID cards, access control cards, visas, tax codes, tickets, vehicle documents, bank notes, checks, postage stamps, credit cards, any chip cards and adhesive labels.

Summary

It is the object of the invention to further improve the forgery-proof security elements and security documents.

This object is achieved by a security element for use for a security document according to claim 1, a security document according to claim 10, a method for producing a security element for use for a security document according to claim 11, a method for producing a security document according to claim 15 and a method for checking the authenticity of a security document according to claim 16 solved. Refinements are the subject of the dependent claims.

The security element for use for a security document has a top side and a bottom side. It comprises a window area which is at least partially transparent to visible light. The window area includes structural elements with dimensions of less than 200 micrometers (200 µm). The structural elements are arranged and designed in such a way that a colored image on the upper side is only visible when the underside is illuminated by means of a display or a display. The colored image can be an image, in particular an individualized, for example a personalized, image.

The image can be, for example, an image, preferably a portrait. In other words, the security element does not show a colored image without backlighting by a display. The structural elements are barely visible and are preferably colorless. Only as a result of backlighting or illumination of the underside with a display is a colored image visible on the upper side due to the arrangement and design of the structural elements in the window.

The authenticity of a security document comprising a security element can easily be checked with the aid of a simple display. At the same time, the structure produced by the structural elements can be recognized as such, but is preferably only recognizable with difficulty, and in particular does not show any colored image. Since a colored image only becomes visible when it interacts with a display, the security element is on the one hand not completely recognizable as such and on the other hand can hardly be copied or only with considerable effort. The security element thus has a particularly above-average level of protection against forgery.

The structural elements can have dimensions between 5 micrometers (5 µm) and 100 micrometers (100 µm). The dimensions of the structural elements are matched to the dimensions of the coloring subpixels of a particular display, for example LCD displays (LCD - liquid crystal display) and / or a TFT display (TFT - thin-film transistor). The dimensions of the structural elements can be based on the dimensions of the coloring subpixels of a display of a mobile phone and / or a smartphone and / or a tablet and / or a computer screen. As a result, the authenticity of the security element or of the security document equipped with it can be checked easily and spatially flexibly with the aid of numerous different, in particular portable, devices. The structural elements can be arranged and designed in such a way that when the underside is illuminated by means of a display on the upper side, a colored portrait is visible.

In order that corresponding coloring subpixels of a display are covered, it is necessary that the structural elements have similar dimensions or dimensions as these. Small deviations result in characteristic moire effects which can be changed by rotating the security element relative to the display. Taking into account the various periodicities, in particular spatial periodicities, the coloring subpixels of the displays, given in ppi, and when using distances that occur taking into account the beat effects of these periodicities, it is advantageous if the structural elements form structures in the window area which for different displays, ie displays with differing periodicities of the coloring subpixels, a color information that is easily perceptible is generated. For example, the structural elements can have dimensions that for a specified range of the periodicity of the coloring subpixels of a display, preferably specified in ppi, when the underside is illuminated by means of a display whose coloring subpixels have a periodicity within the specified range the top is visible, for example an individualized colored image that can be personalized. This allows for a variation in the pixel spacing of different displays. The security element can therefore also be verified in particular in connection with a display with a higher resolution.

In a further variant, the structural elements can form at least one structure which has a periodicity that has a greatest common divisor with a plurality of fixed periodicities of the coloring subpixels of different displays. By controlling the display used, the display periodicities can be brought into agreement with the periodicity of the introduced structure to such an extent that the desired color information or the colored image can be recognized. The consideration of the greatest common divisor and the consideration of the beat effects can also be used in combination.

In a further variant, different periodicities of the structural elements are arranged in different orientations, the periodicity of the structural elements in a specific orientation being matched to the dimensions and / or periodicity of the subpixels of a specific display. For example, the structural elements with different or deviating periodicity are at an angle to one another. By rotating the plane with the structural elements, it is possible to match the defined periodicities of the coloring subpixels of a particular display.

The structural elements are produced by laser processing. The structural elements are advantageously designed as blackenings and / or as material removal, for example as perforations, and / or as bores. In particular, by means of laser radiation, it is possible to generate blackening in the material and / or to change the material structures by removal or perforation. Other structuring methods, for example micro-printing, for modifying the transparent window are also possible.

A microstructure produced by structural elements is preferably colorless without illumination by means of a display. The microstructure can therefore be recognized as such, but is colorless without a light-emitting display behind it. Once a structure has been introduced, it cannot be copied or changed.

By controlling or coloring the display, further effects can be generated in interaction with the microstructure. The color pixels of the display can be controlled, for example, by an application (app). By changing the color pixels of the display, different effects can be achieved in connection with the microstructure, which can be further developed without the structure itself having to be changed.

In a further variant, the window area comprises a light control film with a large number of parallel grooves. By using a light control film or lamella film, as for example in DE 10 2012 109 064 A1 described, parallax barriers arise, which can be used to create a 3D effect.

In principle, the structural elements can be arranged on at least one surface, that is to say the upper side or the lower side, of the window area or in the interior or within the security element. The structural elements can be designed as depressions, elevations or cavities. It is also possible that the structural elements differ in terms of their optical and / or mechanical and / or chemical properties from the material of the Differentiate between security elements. In other words, the structural elements can have optical, mechanical or chemical properties that differ from the material of the security element. The variants mentioned can be combined with one another as required. They have the advantage that they can be produced comparatively easily and inexpensively and at the same time significantly improve protection against counterfeiting.

The individual structural elements can have a length and / or a width and / or a depth or a height and / or a distance between adjacent structural elements of less than 100 micrometers, for example between 100 nanometers to 100 micrometers. Dimensions in terms of length and / or width and / or the distance between 5 micrometers and 30 micrometers, as well as depths between 0.5 micrometers and 20 micrometers are advantageous because they require special manufacturing processes, for example material processing with ultra-short laser pulses, and the structure is not immediately recognizable. The dimensions of length, width, depth and / or distance can assume different values from one another.

The structural elements can be designed as bores, that is to say as depressions with a circular cross section, for example as micro or nano laser bores. These have the advantage that they can be manufactured comparatively easily with ultrashort laser pulses.

The security element can be designed for a specific security document or for a specific type of security document with specific security information. In this case, the structure and the colored image that can be generated with it can contain security information for the specific security document. In this way, an individualizing structure can be applied, thereby further improving the security against forgery. For example, a microstructuring in a transparent window of an identification document can show a personalized image, for example a portrait of the owner of the identification document, when illuminated by a display.

Without restricting the type of material, the security element can comprise an at least partially transparent material and / or polycarbonate and / or glass. For example, the security element can be completely or partially transparent, in particular transparent to visible light.

The security document comprises a window area with a security element described above. The security document is preferably composed of a number of layers, at least one layer comprising a previously described security element. The security document basically has the advantages of the proposed security element which have already been mentioned. The security document can in particular comprise layers connected to one another by lamination. The layers can be, for example, a substrate, a printing layer which contains security-relevant information, and a cover layer, the printing layer being arranged between the substrate and the cover layer. At least one of the layers preferably comprises a security element.

The method for producing a security element for use for a security document is characterized in that an at least partially transparent material for the window area is provided with structural elements with dimensions of less than 200 micrometers (200 µm) by means of laser processing, the structural elements being arranged and configured in this way are that when the underside is illuminated by means of a display, a colored image is visible on the upper side, in particular an individualized colored image, which can be a personalized image. In particular, structural elements with dimensions in the range between 5 micrometers (5 μm) and 30 micrometers (30 μm) can be applied to the material of the security element or introduced into the material of the security element. An above-described security element can be produced by means of the method. The method has the advantage that it enables the production of a security element which has a high level of protection against copying and forgery in a simple and inexpensive manner.

The structural elements can also be produced by micro-printing. The structural elements can be produced on at least one surface of the at least partially transparent material by removing material. In addition, the structural elements can be produced on or in at least one surface, that is to say the top or the bottom, of the security element in the form of elevations and / or depressions. Additionally or alternatively, the structural elements can be produced in the interior or within the security element in the form of cavities. The security element can be manufactured at least partially from a film that is at least partially transparent to visible light. In this case, depressions can be produced in at least one surface of the film, in particular by removing material.

In a preferred variant, laser bores in the micrometer range and / or nanometer range are made in at least one surface of the security element. These can have a diameter between 100 nanometers (100 nm) and 100 micrometers (100 µm), for example between 5 micrometers and 30 micrometers, and / or a depth between 100 nanometers (100 nm) and 100 micrometers (100 µm), for example between 500 nanometers and 20 micrometers.

Structural elements in the form of elevations can be generated through local foaming and / or through high-resolution 3D printing technology, for example by means of two photon polymerization.

The structural elements are advantageously generated by means of ultrashort laser pulses, for example with a pulse duration of less than 10 picoseconds (10 ps), in particular less than 1 picosecond (1 ps) or less than 500 femtoseconds (500 fs). The use of ultra-short laser pulses enables precise production and efficient generation of the structural elements. In particular, ultrashort laser pulses minimize or avoid thermal or mechanical damage to the structural element during processing. With a suitable choice of the machining parameters, almost melt-free machining with high precision is possible.

Ultrashort laser pulses make it possible to provide the surface or the preferably transparent cover layer above a personalized layer of a security document with a structure depicting the second representation, the dimensions of the structural elements being in the micrometer or nanometer range. For this purpose, the material is preferably moved relative to the focused laser beam or scanned from the focused laser beam by means of a movable mirror. Due to the short interaction time of the ultrashort laser pulses with the material, the material removal does not cause any color change in the material and the elements of the structure are colorless and preferably consist of microbores.

The method for producing a security document, in particular a security document, relates to a security element which is composed of a number of layers. In the context of the method, at least one layer is produced from a security element or a security element produced according to the method described above. The at least one layer is connected to a number of further layers, for example glued or laminated, so that the security document has an at least partially transparent window area with a structure produced by the structural elements. In principle, the above-described method for producing a security element can be part of the method for producing the security document.

As part of the method for checking the authenticity of a security document, the window area of the security document is illuminated on its underside by means of a display and viewed on its upper side. As a result of the lighting on the upper side, a colored image, for example a portrait of the document owner, becomes visible. As already described above, a simple and inexpensive authenticity check of a security document is possible, since in particular no special checking devices are required.

In a variant, the periodicity of the subpixels of the display can be brought into agreement with a periodicity of the structure introduced to such an extent that the colored image is visible on the upper side. This enables the use of different displays with different periodicity of the subpixels. In other words, the colored image can be generated with different displays with different resolutions and thus the authenticity of the security document can be checked.

The structure of the security element can be designed in such a way that it can be recognized as a matted surface when viewed at a defined angle or angular range. When viewed perpendicular to the surface, the structure is preferably not visible to the naked eye. The structure can be seen when viewed under a microscope.

Figure list

• 1 schematisch und ausschnittsweise vergrößert ein Sicherheitselement und ein darunter angeordnetes Display in einer perspektivischen Ansicht; und
• 2 schematisch ein Sicherheitsdokument in einer perspektivischen Ansicht.

Further features, properties and advantages of the invention are described in more detail below on the basis of design variants with reference to the accompanying figures. All of the features described so far and below are advantageous both individually and in any combination with one another. Here show:

• 1 schematically and partially enlarged a security element and a display arranged underneath in a perspective view; and
• 2 schematically a security document in a perspective view.

The 1 shows schematically a security element 1 and a display below 10 . The security element 1 is designed as a window element that is transparent to visible light and has one of structural elements 2 Structure formed on that in a window area 6th is arranged. The structural elements 2 have dimensions in the micrometer range, specifically less than 200 micrometers. The security element 1 has a top 4th and a bottom 5 on. In the 1 is the display 10 on the bottom 5 arranged, for example on the security element 1 created and illuminates the security element 1 from the bottom 5 . the display 10 comprises a large number of coloring sub-pixels 11 . The structural elements 2 of the security element 1 are arranged in such a way that when the underside is illuminated 5 of the security element 1 by means of a display 10 on the top 4th of the security element 1 a colored image, for example a portrait, is visible. The colored image is used in conjunction with the display 10 by the size and arrangement of the structural elements 2 which when considering the security element 1 towards its top 4th certain subpixels 11 des at the bottom 5 arranged displays 10 conceal, generated.

The colored image can also be activated by activating the display accordingly 10 or the corresponding coloring subpixels 11 modify. In particular, the periodicity of the coloring subpixels can be used 11 with a periodicity one through the structural elements 2 generated structure can be matched or adapted to this. With the display 10 it can be a display of a cell phone, a smartphone, a tablet, a notebook, etc.

The structural elements can be produced by laser processing and / or micro-printing. They can be created by blackening or material removal, for example laser drilling.

The 2 shows schematically a security document 20th . The security document 20th has a top 14th and a bottom 15th on and includes a related to the 1 described security element 1 . The security document 20th comprises an area transparent to visible light, preferably a window area 16 in which the security element 1 is arranged or which at least partially by the security element 1 is formed. For example, the security element 1 consist exclusively of the window area or in the form of one of several layers 3 be designed. The the security element 1 forming or comprehensive layer 3 can with further layers 3 be firmly connected, for example by lamination. In this way, a security document made up of several layers 20th with a security element 1 be equipped.

With the security document 20th For example, it can be an identification document, in particular a passport, an identity card, a driver's license, etc. The security document 20th has a significantly improved protection against forgery, since the structural elements 2 themselves are barely visible and in particular from the structural elements 2 or the structure alone is not clear which colored image it is when illuminated by a display 10 produce. In addition, the authenticity of the security document 20th with the help of a display 10 can also be checked very easily and without further aids.

List of reference symbols

1

Security element

2

Structural elements

3

layers

4th

Top

5

bottom

6th

Window area

10

Display

11

coloring subpixels

14th

Top

15th

bottom

16

Window area

20th

Security document

Claims (17)

Security element (1) for use for a security document (20), comprising: - an upper side (4); - A bottom (5) and a window area which is at least partially transparent to visible light; in which - The window area (6) comprises structural elements (2) with dimensions of less than 200 micrometers (200 microns), which are arranged and configured that only when the underside (5) is illuminated by means of a display (10) is a colored image on the Top (4) is visible; - The dimensions of the structural elements (2) matched to the dimensions of the colored subpixels (11) of an LCD display and / or a TFT display and / or a display of a mobile phone and / or a smartphone and / or a tablet and / or a computer screen are; and - The structural elements (2) are produced by laser machining. Security element (1) according to Claim 1 , characterized in that the structural elements (2) have dimensions for a defined area of a periodicity of the coloring subpixels (11) of a display (10) when the underside (5) is illuminated by means of a display (10), the coloring subpixels (11) of which have a periodicity within the defined area, a colored image on the upper side (4) is visible. The security element (1) according to one of the preceding claims, characterized in that the structural elements (2) form at least one structure which has a periodicity which has a greatest common divisor with a plurality of fixed periodicities of the coloring subpixels (11) of different displays (10) ) Has. The security element (1) according to any one of the preceding claims, characterized in that different periodicities of the structural elements (2) are arranged in different orientations, the periodicity of the structural elements (2) in a specific orientation on the dimensions and / or periodicity of the subpixels of a specific displays. The security element (1) according to any one of the preceding claims, characterized in that the structural elements (2) are arranged and designed in such a way that when the underside (5) is illuminated by means of a display (10) a colored portrait is visible on the upper side (4) is. Security element (1) according to one of the preceding claims, characterized in that the structural elements (2) are designed as blackenings and / or as material removal and / or as bores. Security element (1) according to one of the preceding claims, characterized in that a microstructure produced by structural elements (2) is colorless without illumination by means of a display (10). The security element (1) according to any one of the preceding claims, characterized in that the window area (6) comprises a light control film with a plurality of parallel grooves. Security element (1) according to one of the preceding claims, characterized in that the structural elements (2) have dimensions between 5 micrometers (5 µm) and 100 micrometers (100 µm). Security document (20) which has at least one window area (16) with a security element (1) according to one of the Claims 1 to 9 includes. Method for producing a security element (1) according to one of the Claims 1 to 9 , characterized in that an at least partially transparent material for the window area (6) is provided by means of laser processing with structural elements (2) with dimensions of less than 200 micrometers (200 µm), the structural elements (2) being arranged and designed in such a way that when the underside (5) is illuminated by means of a display (10), a colored image is visible on the upper side (4). Procedure according to Claim 11 , characterized in that the structural elements (2) are produced on at least one surface of the at least partially transparent material by removing material. Method according to one of the Claims 11 or 12th , characterized in that laser bores in the micrometer range and / or in the nanometer range are made in at least one surface of the at least partially transparent material. Method according to one of the Claims 11 or 12th , characterized in that the at least partially transparent material is provided with structural elements (2) with dimensions between 5 micrometers (5 µm) and 100 micrometers (100 µm). Method for producing a security document (20) according to Claim 10 , which is built up from a number of layers (3), characterized in that at least one layer (3) with a security element (1) according to one of the Claims 1 to 9 or one according to the Claims 11 to 14th produced security element (1) is manufactured and is connected to a number of further layers (3) in such a way that the security document (20) has an at least partially transparent window area with a structure produced by the structural elements (2). Method for checking the authenticity of a security document (20) according to Claim 10 wherein the window area (16) of the security document (20) is illuminated on its underside (15) by means of a display (10) and viewed on its upper side (14). Procedure for checking authenticity Claim 16 , characterized in that the periodicity of the subpixels (11) of the display (10) is brought into agreement with a periodicity of the introduced structure to such an extent that the colored image is visible on the upper side (4).

Images