EP3967510A1 - Security document with viewing direction-dependent safety feature - Google Patents

Abstract

The invention relates to a security document with a security feature that depends on the viewing direction, the security document (10) having a document body (1) with a transparent volume region (20) extending at least as far as an outer surface (12), in which the document body (1) consists of a transparent Material is formed, in the interior of which localized laser-induced material changes (500) are formed, the laser-induced material changes (500) being formed at different distances relative to the outer surface (12) in the transparent volume region (20). In addition, the invention relates to a method for Creation of such a security document.

Description

The invention relates to a security document with a security feature that is dependent on the direction of viewing and a method for its production. In particular, the invention relates to a security document with a document body, which has a transparent volume region extending at least up to one surface, in which the document body is formed from a transparent material, in the interior of which localized laser-induced material changes are formed.

Security documents are provided with features intended to protect them against imitation and/or falsification. These features are referred to as security features since they protect such a security document against falsification and/or unauthorized manufacture. Physical objects that have at least one security feature are also referred to as security elements.

A group of security features can be checked optically or visually. These features are referred to as optical or visual security features. A subgroup of these shows a viewing direction dependent effect. This means that the optical or visual detection of the security document from different viewing directions provides different optically or visually perceptible views of the same surface of the security document.

A group of security features that show an effect that depends on the viewing direction and in which the feature is formed by material changes inside a transparent area are so-called changeable laser images (CLI) or multiple laser images (MLI), in which lens-like structures are embedded in the surface of a document body are imprinted. Due to refraction effects on these lens-like elements, incident laser light is focused when the markings are formed inside the document body and material changes are usually produced in the focus and in areas in front of or behind the focus of the beam path used for production. As a rule, the material changes are discolouration. In particular, plastic layers are blackened to a greater or lesser extent. When viewing the security document, the blackening is optimally in focus only from the viewing direction through the lens-like structure of the surface that corresponds to the direction of incidence of the light that was irradiated to generate the material changes. If the document body is viewed from a different viewing direction than the original irradiation or generation direction, the material changes are not perceptible or only perceptible in a modified way.

A disadvantage of security elements of this type is that complex structures must be formed on the surface, which can also be adversely affected by environmental influences and destroyed. Furthermore, the markings all lie in the focal plane of the lens-like elements. This makes it possible to replace the stored information, for example in a forged document, with printed information, in that the body of the document is made of several layers, as is otherwise customary, in a lamination process and the information is printed on one of the transparent layers inside instead of be introduced with a laser. In principle, in the case of a CLI or MLI feature, the information is formed on the inside in relation to an outside of the document body in a narrowly defined distance range from this surface. Otherwise the material changes are not in the focal plane of the lens-like elements.

The invention is based on the object of creating a security document with a viewing direction-dependent security feature and a method for its production, which lead to security documents with document bodies that are easy to verify optically on the one hand and on the other hand offer good protection against delamination and replacement of individual layers and against mechanical external influences are well protected.

The invention is achieved by a security document having the features of patent claim 1 and a method having the features of patent claim 11 . Advantageous configurations of the invention result from the dependent claims.

The invention is based on the idea of forming the laser-induced material changes at different distances relative to the outer surface in a transparent volume area of the document body. This ensures that the different levels, which, for example, from different Material layers that are laminated to each other are formed, cannot be subsequently separated from one another and replaced by others and/or manipulated without this being perceptible in the security feature.

definitions

Volume areas through which light propagation for at least one wavelength range of the visible spectrum is possible without appreciable diffuse scattering are considered to be transparent. Such an area can be colored. Imaging according to geometrical optics can be carried out through a transparent area at least with light of a wavelength range. Clear window panes are, for example, made of transparent material within the meaning of what is described here. However, clear tinted window panes are also transparent in the sense of the technical teaching described here.

A level structure is a structure in three-dimensional space formed from a large number of material changes, which can be understood as the support points of a grid network that spans a level or surface. This means that a grid would be created that spans the surface or level if neighboring material changes were connected via grid lines. Typically, the average spacing between adjacent variances will be less than 10 times the extent of any one of the variances, more preferably less than 5 times the extent of any one of the variances, and most preferably less than 2.5 times the extent of any one of the variances. The material changes that form the support points do not all have to be in one plane, but can be arranged in several planes. However, the resulting grid structure that results from connecting the support points with the neighboring support points must form a surface or plane that may have a certain plane thickness or surface thickness, which is due to the fact that not all material changes are in exactly one plane or surface.

A planar structure is flat if the structure spanned by the material changes has a small extension across the surface in relation to the extension of the surface itself. Preferably is the extension of the flat plane structure perpendicular to the surface is limited to the extent of the individual material changes. However, the spanned flat level structure can also be designed as a quasi multi-layer “grid structure”, so that the flat level structure has a level structure strength that is determined by the distance between the “grid levels”/marking levels of the material changes, the number of grids/marking levels and the dimensions of the individual material changes is. In any case, however, the level structure thickness is at least one order of magnitude smaller than the extent of the surface of the level structure.

Plane is a planar structure if it can be viewed as the physical embodiment of a portion of a mathematical noncurved plane. Here, the plane structure strength and a "surface roughness" are neglected if neighboring material changes are not in one plane.

A plane structure is referred to as semi-planar if it can be viewed as the physical embodiment of a part of a mathematical plane that does not have a curvature at any point of the plane along a spatial direction of Euclidean space.

Level structures are referred to as partial plan, in which at each point of the level structure there is a viewing direction under which, when considering the respective point of the level structure, only the extension of the level structure strength is shown.

A planar, level structure can be thought of as an "extrusion body" that is formed by "extruding" the material changes arranged along an elongated linear or strip-shaped structure along a spatial direction that is oriented transversely or perpendicularly to the linear or strip-shaped structure. which in this picture means that further material changes are generated along the direction. It is clear to the person skilled in the art that the laser markings are not introduced into the transparent volume region via extrusion and that this description is only intended to describe the geometric shape that the markings jointly span.

Preferred Embodiments

In particular, a security document with a security feature that is dependent on the viewing direction is proposed, the security document having a document body with a transparent volume region extending at least to an outer surface, in which the document body is formed from a transparent material, in the interior of which localized laser-induced material changes are formed. The laser-induced material changes are formed at different distances relative to the outer surface in the transparent volume area.

Furthermore, a method for generating a security document body of a security document with a viewing direction-dependent security feature is created, which comprises the steps: providing the document body with a transparent volume region extending at least up to an outer surface, in which the document body is formed from a transparent material; Generating material changes by means of a laser in the interior of the transparent volume area, the laser-induced material changes being formed at different distances relative to the outer surface in the transparent volume area.

The security feature is particularly easy to verify if at least a large number of the laser-induced material changes span a planar or semi-planar flat plane structure whose plane structure strength is of the order of magnitude of the extent of the individual material changes spanning the flat plane structure. In terms of magnitude here means that the level structure strength can range from a simple expansion of individual material changes to 10 to 15 times the expansion of individual material changes. Overall, however, the planar structure thickness is preferably in the range of less than 1 mm, more preferably less than 0.5 mm, most preferably in the range between 1 μm and 150 μm. In some embodiments, the level structure thickness is advantageously a multiple of the extent of the individual material changes spanning the flat level structure and is advantageously less than 100 μm. In some embodiments, the plane structure strength corresponds to the expansion of individual material changes. For all According to some embodiments, if, for example, a layer is exchanged or manipulated inside such a document body, this is easily recognizable by a lack or an offset of material changes in the flat plane structure.

An embodiment is particularly preferred in which at least one distinct viewing direction corresponds to the one planar or semi-planar flat plane structure, wherein the at least one distinct viewing direction is defined relative to the document body, and of the one planar or semi-plane flat plane structure at least in one section only one Level structure strength of the flat level structure can be detected when viewed from the one distinguished viewing direction of the document body. Such a flat plane structure thus has at least one section that loses its two-dimensional character when viewed from one direction and appears as a narrow, more line-like marking. On the other hand, the two-dimensional nature of the arrangement of the flat plane structure spanned by the at least a large number of laser-induced material changes can be seen from other viewing directions.

If the flat plane structure is planar, the entire flat plane structure formed can be seen under the at least one marked viewing direction as a straight, spatially delimited marking, the extent of which across the straight line corresponds to the thickness of the flat plane structure.

In addition to a planar design of the level structure, other forms are conceivable and realizable. In this way, for example, semi-planar wavy plane structures can be realized. Partially planar structures, for example in the form of a cone shell or shapes similar to that of a Möbius strip, can also be implemented. The forms mentioned are exemplary and do not limit a further variety of forms.

One embodiment provides that the at least one planar or semi-planar flat level structure, at least in one section, is formed by a trace curve of one section of the planar or semi-planar flat level structure with a planar trace level inside the volume region and the at least one corresponding to the at least one section excellent viewing direction can be approximated by the trace curve parallel to the one excellent viewing direction is "extruded" as explained above. The track plane can be, for example, a plane oriented parallel to the outer surface in the interior of the transparent volume area. The line of intersection of the flat plane structure with the trace plane produces trace elements in sections, which correspond to marked viewing directions, in order to reconstruct a part of the flat plane structure by "extruding" the trace section.

Particular preference is given to embodiments which contain a plurality of planar or semi-planar flat plane structures formed separately from one another. In one embodiment it is therefore provided that at least a further plurality of laser-induced material changes spans a further planar or semi-planar flat level structure whose level structure strength is of the order of magnitude of the extent of the individual material changes spanning the further flat level structure. It is also possible to protect larger areas related to the outer surface of the document body via the security feature by forming the different flat plane structures in different areas relative to the outer surface of the document body inside the transparent volume area.

Particular preference is given to embodiments in which at least one further distinct viewing direction corresponds to the one further planar or semi-planar flat plane structure, with the at least one further distinct viewing direction being defined relative to the document body, and of the one further plane or semi-plane flat plane structure at least in one Only one level structure strength section can be detected when looking at the document body from the one further excellent viewing direction. The further flat plane structure can thus also be detected at least in sections as a track from one viewing direction, the further marked viewing direction, whereas it is recognizable as a surface formed in the interior from other viewing directions.

Preferably, the at least one distinguished viewing direction of the one planar or semi-planar flat plane structure and the at least one other distinguished viewing direction of the at least one further planar or semi-plane flat plane structure are different from one another and thus characterize different viewing directions of the document body. So from the one Excellent viewing direction to recognize at least a portion of a plan or semi-planar flat level structure as a narrow track, while the two-dimensional extent of the other plan or semi-planar flat level structure is perceptible. Conversely, from the further distinguished viewing direction, the further planar or semi-planar flat level structure can be perceived as a narrow track at least in one section and the one planar or semi-planar flat level structure can be perceived as a surface formed in the transparent volume. Tilting the document body in such a way that the user alternately assumes the one prominent viewing direction or the one further distinguished viewing direction relative to the document body results in an effect that is clearly dependent on the viewing direction occurring in the security document body. The at least one distinguished viewing direction and the at least one further distinguished viewing direction are therefore particularly preferably different from one another and are not oriented parallel to the surface normal of the outer surface of the document body. If the document body is viewed from the outer surface perpendicularly to its outer surface, the one planar or semi-planar flat structure and the other planar or semi-planar flat structure, which are each spanned by a large number of material changes, are each inclined relative to the surface surfaces extending inward through the volume are recognizable. As in the other embodiments, this leads to a clearly different appearance from other known laser markings being recognizable inside transparent volume layers.

The material changes are carried out by means of ultra-short laser pulses, the light of which is focused inside the document body using optics which are separate from the document body and have a numerical aperture NA>0.4. This strong focus means that the material changes are locally limited and only occur in the focus area. Unlike in the case of laser markings, which are carried out via refractive structures in the surface of the document body, the extent transverse to the outer surface of the document body is therefore no greater than parallel to the outer surface. In the case of classic laser markings, which cause discoloration, this is generally not the case and the extent transverse to the surface is considerably larger than parallel to the surface. Apparent falsifications through classic laser marking processes, even if the lens elements are only on the External surface are placed during production can thus be easily distinguished from the new security feature. As a rule, these differences can be seen with the naked eye.

The fact that the material changes partially cover a volume region behind it and/or at least limit or modify its perception can be used in embodiments to generate color effects that are dependent on the viewing direction. In some embodiments it is therefore provided that one or more colored areas are formed in the one transparent volume area extending at least up to an outer surface or below the one transparent volume area extending at least up to the one outer surface and spaced apart from the one outer surface, so that a covering of the one colored area or at least one of the several colored areas by the multitude of material changes of the one planar or semi-planar flat plane structure or further multitude of material changes of the one further planar or semi-plane flat plane structure varies in each case depending on the viewing direction. If the colored areas are formed, for example, below the transparent area and the flat planes are formed up to the lower edge of the transparent volume area, then, for example, two colored areas that cause a different colored impression on an observer or a color analysis can be on the different sides of a track are arranged, which result from the contact trace of a plane in which the at least one planar or semi-planar flat plane structure lies, with the plane in which the paint is applied, or a further trace resulting from the contact trace of a further plane in which the another planar or semi-planar flat plane structure lies, with the plane of the application of paint. If different color areas are formed on the different sides of the track, the color changes when the viewing direction is changed. In some viewing directions, the colored area on one side of the track is at least partially obscured by the one flat plane structure. On the other hand, when viewed from other directions, the application of paint on the other side of the trace is concealed by the flat layered structure. This creates a color shift effect that depends on the viewing direction.

In some embodiments, information that can be detected depending on the viewing direction is stored in the form of patterns. Relative to a basic pattern of, for example, colored areas arranged like a chessboard, flat plane structures are formed, so that by deliberately covering individual areas with planar or semi-planar flat plane structures from a large number of material changes, the information can be recorded in the form of patterns that can be derived from the basic pattern through the complete or partial coverage of some of the colored areas result. In one embodiment, it is therefore provided that the multiple colored areas form a basic pattern and, relative thereto, the plurality of material changes of the one planar or semi-planar flat layered structure and/or the further plurality of material changes of the further planar or semi-planar flat layered structure and/or at least one additional one A large number of material changes are arranged in at least one additional planar or semi-planar flat level structure, so that different patterns can be detected from different viewing directions, which differ from one another in that different colored areas of the basic pattern are caused by the large number of material changes in the planar or semi-planar flat level structure and/or or the further planar or semi-planar flat plane structure and/or one or more of the at least one additional planar or semi-planar flat plane structure covered and/or uncovered are.

In yet other embodiments, it is provided that the one transparent volume area that extends at least up to the one outer surface comprises differently colored areas and at least some of the laser-induced material changes are formed in one or more of the differently colored areas in order to thereby reduce the local color impression in the interior of the change security document. The advantage of the invention is that the material changes can be introduced in a targeted and varied manner both laterally and with respect to a distance from the one outer surface. Some embodiments therefore provide that the differently colored areas are areas layered on top of one another in relation to a perpendicular view of the one outer surface. These different areas can be produced, for example, by transparent colored foils that are laminated together to form the document body. In this case, an outer or uppermost area can also be colorless, ie not colored.

The laser-induced material changes are particularly preferably designed as cavities or small hollow volumes. In this way, specific color impressions can be generated by the laser-induced material changes arranged in the different levels.

Such laser-induced material changes can be generated by means of ultra-short laser pulses, the light of which is focused inside the document body with optics that are separate from the document body and have a numerical aperture NA>0.4. With some materials, such a targeted local modification can be achieved from a numerical aperture of 0.3, but larger numerical apertures are desirable and preferred. In addition to the laser-induced material changes in the form of hollow volumes, discolorations, in particular blackening, can also be produced as an alternative or in addition, which, however, are also produced with sharply defined localization using ultra-short laser pulses and high focusing with a numerical aperture >0.4.

The material changes that are formed in the clear, uncolored, transparent material and that jointly span a plane structure can also advantageously be formed as cavities that are optically perceptible due to a refractive index difference on the boundary surfaces of the cavities and the resulting interactions with light. In the clear material, too, the material changes can alternatively or additionally be formed via sharply delimited, localized blackening or gray coloring.

Fig. 1

eine schematische isometrische Ansicht eines vollständig transparenten Dokumentkörpers eines Sicherheitsdokuments;

Fig. 2a

eine schematische isometrische Ansicht des Dokumentkörpers nach Fig. 1, betrachtet aus einer ausgezeichneten Betrachtungsrichtung;

Fig. 2b

eine weitere schematische isometrische Ansicht des Dokumentkörpers nach Fig. 1, betrachtet aus einer weiteren ausgezeichneten Betrachtungsrichtung;

Fig. 3

eine schematische Ansicht eines weiteren Dokumentkörpers, bei dem unterhalb des transparenten Volumenbereichs farbige Bereiche ausgebildet sind;

Fig. 4a

eine schematische isometrische Ansicht des Dokumentkörpers 1 nach Fig. 3, betrachtet aus einer ausgezeichneten Betrachtungsrichtung;

Fig. 4b

eine weitere isometrische Ansicht des Dokumentkörpers 1 nach Fig. 3, betrachtet aus einer weiteren ausgezeichneten Betrachtungsrichtung;

Fig. 5

eine schematische isometrische Ansicht eines weiteren Dokumentkörpers, der aus eingefärbten transparenten Bereichen gebildet ist;

Fig. 6a

eine schematische isometrische Ansicht eines Dokumentkörpers, in dessen Inneren ein schachbrettartiges hell-dunkel Muster mit als Sichtbarrieren ausgebildeten planen flachen Ebenenstrukturen ausgebildet ist; und

Fig. 6b

eine schematische isometrische Ansicht eines Dokumentkörpers, in dessen Inneren ein schachbrettartiges aus bunten gedruckten Bereichen gebildetes Muster mit als Sichtbarrieren ausgebildeten planen flachen Ebenenstrukturen ausgebildet ist.

The invention is explained in more detail below with reference to a drawing. Here show:

1

a schematic isometric view of a completely transparent document body of a security document;

Figure 2a

Figure 1 shows a schematic isometric view of the document body 1 , viewed from a distinguished viewing direction;

Figure 2b

another schematic isometric view of the document body 1 , viewed from another excellent viewing direction;

3

a schematic view of a further document body, in which colored areas are formed below the transparent volume area;

Figure 4a

a schematic isometric view of the document body 1 after 3 , viewed from a distinguished viewing direction;

Figure 4b

another isometric view of the document body 1 3 , viewed from another excellent viewing direction;

figure 5

a schematic isometric view of another document body, which is formed from colored transparent areas;

Figure 6a

a schematic isometric view of a document body, inside which a chessboard-like light-dark pattern is formed with planar, flat plane structures designed as visual barriers; and

Figure 6b

a schematic isometric view of a document body, in the interior of which a checkerboard-like pattern formed from colorful printed areas is formed with planar flat plane structures formed as visual barriers.

In 1 a document body 1 of a security document 10 is shown schematically. In all figures the same reference numbers are used for the same technical features. It is clear to the person skilled in the art that greatly simplified embodiments are described here. the inside 1 The document body 1 shown can contain a large number of other security features and security elements which are not shown here. In addition, the proportions of the individual features and elements shown are not shown realistically.

The document body 1 has an upper side 2 and an opposite lower side 3 . In between, the document body is formed from a completely transparent volume area 20 . This thus extends at least to the one outer surface 12, which is the upper side 2 of the document body 1. The opposite outer surface 13 corresponds to the underside 3.

A viewing direction-dependent security feature 100 is formed by a plurality of microscopic material changes 500 produced by a laser in the interior of the transparent volume region 20, which extends at least to the one outer surface 12. The material changes are formed at different distances measured perpendicularly to the outer surface 12 in the interior of the transparent volume area 20 . This means that at least two material changes can always be found that have a different distance to the outer surface. If the distance to the outer surface is discussed here, this is measured parallel to the surface normal 15 of the outer surface 12 in each case.

However, the statement that the material changes 500 have different distances from the outer surface 12 does not mean that two arbitrarily selected material changes in each case have to have different distances from the outer surface 12 . This means that at a same distance, i.e. in a plane parallel to the outer surface, several of the material changes 500 can be present. However, the security feature always has at least two material changes that are at a different distance from the outer surface 12 .

At the in 1 In the embodiment shown, a large number of microscopic material changes are formed in the interior of the transparent volume region 20, which are arranged in relation to one another in such a way that they together form a flat plane structure 41. The flat plane structure 41 is planar in the illustrated embodiment. The flat plane structure 41 is inclined above the outer surface 12 at an angle α.

A structure is understood to be a flat planar structure that locally has only a small extent perpendicular to the planar extent. This expansion is over the areal extension almost constant. It is preferably in the order of magnitude of the extent of the material changes or a multiple of the extent of the material changes, but preferably in the range of less than 1 mm, more preferably less than 0.5 mm, most preferably in the range between 1 μm and 150 μm.

A distinct viewing direction 140 is associated with the one plane, flat plane structure 41, which has the angle α with respect to the surface normal of the outer surface. The viewing direction is thus oriented parallel to the flat side of the plane structure 41 . If the document body 1 of the security document 10 is viewed from the one marked viewing direction 140, only the level structure strength of the one flat level structure 41 can be detected. This means that the flat plane structure is perceived as a thin stretch or line in the transparent volume area 20 of the document body 1. However, if the document body 1 is viewed from other viewing directions, the two-dimensional extent of the flat level structure 41 can be seen.

This is exemplary in Figures 2a and 2b shown where Figure 2a the isometric view viewed from the one distinguished viewing direction 140 and the Figure 2b represent a view of the document body 1 from a further distinguished viewing direction 150 .

The further marked viewing direction 150 corresponds to a further flat plane structure 51 spanned from a further plurality of material changes 500. In the embodiment shown, this further flat plane structure 51 is also planar and oriented at an angle of inclination β relative to the surface normal 15 of the outer surface 12. The further marked viewing direction 150 is oriented parallel to the further flat plane structure 51 . Under the further marked viewing direction 150, the further flat plane structure 51 thus appears as a straight line or segment 151 (cf Figure 2b ). On the other hand, the two-dimensional extent of the further flat level structure 51 in the view of FIG Figure 2a , which corresponds to the one distinguished viewing direction 140, can be seen clearly.

The document body 1 after 1 contains, in addition to the one flat plane structure 41, an additional flat plane structure 42 oriented parallel thereto, which is formed from a multiplicity of material changes, and an additional further flat plane structure 52, which is oriented parallel to the further flat plane structure 51. If the document body 1 is perceived optically or visually from different viewing directions, different optical impressions result. Under one excellent viewing direction 140 one takes the view of Figure 2a true, in which the one flat plane structure 41 and the additional flat plane structure 42 are perceptible as narrow straight lines 141, 142, respectively, and the further flat plane structure 51 and the additional further flat plane structure 52 are perceptible as areas, respectively. This is reversed when the document body 1 is perceived from the further distinguished viewing direction 150, as is shown in Figure 2b is shown. In this case, the two-dimensional extent of the one flat level structure 41 and the additional flat level structure 42 can be seen. On the other hand, the further flat plane structure 51 and the additional further flat plane structure 52 can each be perceived as narrow straight line-like structures 151, 152.

In 3 another document body 1' is shown, which differs from the document body 1 after 1 differs in that an opaque volume area 30 is arranged below the transparent volume area 20 and is firmly connected to the transparent volume area 20 . A top side 32 of the opaque volume area 30 has colored areas 80 here. In the illustrated embodiment, the colored areas 80 are formed in strips, first colored areas 81 and second colored areas 82 are formed alternately, for example by an imprint. The strip-like areas are aligned parallel to the longitudinal extensions of the flat plane structures 41, 42 and 51, 52, respectively. This means that in the case of a plane, flat level structure 41, 42 or 51, 52, which is viewed from an associated excellent viewing direction 140 or 150 and can be perceived as a straight line 141, 142 or 151, 152 (cf Figures 4a and 4b ), this line 141, 142; 151, 152 preferably separates a first colored area from a second colored area. Thus, for example, the one colored area 81 is perceived on one side of the line 141 when viewed from the designated viewing direction 140 and the other colored area 82 is perceived on the other side. If you change the viewing direction, then either a colored area 81 or the other colored area 82 is at least partially covered by the one planar flat plane structure 41 or at least changed with regard to the color perception.

In Figures 4a and 4b the views of the document body 1 ′ are shown correspondingly for the one distinguished viewing direction 140 and the one further distinguished viewing direction 150 . The effect described is clearly visible. while in Figure 4a the one colored area 81 on the left can be perceived unhindered and uncovered by the one flat level structure 41 and the second colored area 82 immediately to the right next to the one flat level structure 41 can also be perceived without being disturbed, a right-hand part of this second colored area 82 is partially covered by the additional one flat plane structure 52 partially obscured. The same applies to the third colored area 83 . The fourth colored area 84, on the other hand, is not covered by any of the flat plane structures 41, 42, 51, 52 and is completely perceptible.

This situation changes in the in Figure 4b illustrated view showing the perception for viewing from the further distinguished viewing direction 150 from which the further flat plane structure 51 and the additional further flat plane structure 52 appear as narrow straight lines or distances 151, 152. The first colored area 81 is almost completely covered by the one flat level structure 41 . The second colored area 82, on the other hand, like the third colored area 83, can be seen almost undisturbed and uncovered. In contrast, the fourth colored area 84 is covered by the additional one level structure 42 .

It is clear to the person skilled in the art that this can produce a wide variety of targeted color shift effects. The plane structures do not each have to extend along one direction through the entire transparent volume area. They also do not have to be aligned "parallel to each other" with respect to a direction.

In figure 5 another embodiment is shown. In this case, the document body 1 comprises three differently colored areas 21-23. In the illustrated embodiment, these are each designed as material layers of the same thickness, oriented parallel to the outer surface 12 . For example, the uppermost colored transparent area 21 is yellow, the middle colored transparent area 22 is cyan and the lowermost colored transparent area 23 is magenta.

The security feature 100, which is dependent on the viewing direction, is formed by a large number of material changes 500 in the interior of the transparent volume area 20, i.e. in the differently colored transparent areas 21-23. There are lightening material changes 541 in the yellow colored area 21 (crosshatching), lightening material changes 542 in the green colored area 22 (hatching from top left to bottom right) and lightening material changes 543 in the magenta colored area 23 (hatching from bottom left to right running above). Brightening material changes are indicated by material changes shown in a round shape. These lightening material changes 541 to 543 can also be arranged with respect to one distinguished direction 140, as shown here, in such a way that they overlap one another when viewed from this distinguished direction. This is equivalent to the fact that the lightening material changes in the differently colored areas jointly span a planar, level structure 41 . In addition, in the illustrated embodiment there are also opaque material changes 551 in the yellow area 21, opaque material changes 552 in the cyan area 22 and opaque material changes 553 in the magenta area 23. Opaque material changes are shown as angular. Their color is indicated by hatching. These material changes 551 to 553 can jointly span, for example, a more planar planar structure 51 that corresponds to a marked further viewing direction 150, so that the various opaquely discoloring material changes 551 - 553 are arranged at least partially one behind the other with respect to the one further marked viewing direction 150. However, other arrangements of the lightening material changes 541 - 543 or opaque material changes 551 - 553 in the different colored areas of the transparent volume area 20 are also possible, with these being introduced into the interior at different distances from the outer surface 12 in order to form the security feature 100 . The colors are again indicated by hatching.

The brightening material changes are preferably formed by cavities which are formed in the individual colored areas by the strongly focused short-pulse laser radiation. The opaque discolorations, on the other hand, are due to carbonization of the plastic material in the individual colored layers brought about. This can be promoted by choosing the appropriate wavelength for the marking.

Optics are used for focusing that have a numerical aperture NA greater than or equal to 0.4. The laser pulses have pulse durations in the range of 500 picoseconds to 1 femtosecond, more preferably in the range of 100 picoseconds to 10 femtoseconds, and most preferably in the range of 1 picosecond to 50 femtoseconds. The strong focus together with the short pulse duration enables the precise and targeted localization of the material changes. Furthermore, the distance between the material change and the outer surface can be set and varied in a targeted manner.

Figure 6a shows a detail of a document body 1, in which a transparent window element in the form of a transparent volume area 20 is formed. Inside the document body 20, colored areas 80 are formed in one plane, for example in the form of a chessboard-like pattern. In one embodiment, the white areas can also be transparent or colorless. The colored areas 80 are formed, for example, by printing a side face of a substrate layer before lamination with other substrate layers to form the document body 1 .

At selected points in the material of the transparent volume area 20 above the colored areas 80, i.e. e.g. above the chessboard-like pattern, planar flat plane structures 41, 51, 61, 71 formed from a multitude of material changes are positioned and formed as visual barriers. The construction of individual material changes is indicated as an example for the planar, flat level structure 71 and representative of the other planar, flat level structures 41 , 51 , 61 . Here, the areal density of the material changes can be varied from level structure to level structure.

In terms of their dimensions, the planar, flat level structures are preferably adapted to the dimensions of the colored areas 80 arranged in the manner of a chess board. Depending on a respective viewing direction 140, 150, 160, 170 (ie an angle relative to the upper side 2) under which the colored areas 80 are detected, different colored areas (80) are visible to the viewer (the detecting camera) covered. Different patterns become detectable. Information (images, text, symbols) can be encoded using this.

In some embodiments, the colored areas 80, i.e. e.g. B. the dark areas of the chessboard-like pattern, and designed as a visual barrier plane flat plane structures generated by microstructures, for example in the form of blackening by means of ultra-short laser pulses in the transparent volume area 20 of the document body 1. If the document body 1 is viewed from the viewing direction 140, the planar, flat plane structure 41 designed as a visual barrier increases the gray or black value at this point in the checkerboard pattern, since the bright checkerboard field is covered. The other planar, flat plane structures 51, 61, 71 shown, designed as visual barriers, do not cause any change for the viewing direction 140. For other viewing directions, these have a pattern-changing effect. For the viewing direction 150, for example, the planar flat plane structure 51 acts as a visual barrier 51 for a previously bright or transparent area. The planar, flat level structure 61 for the viewing direction 160 or the planar, flat level structure 71 for the viewing direction 170 have an analogous effect.

In this way, four different pieces of information can be entered into one field of a document body, each of which is visible from 4 different viewing angles. The visual barriers, ie the planar, flat level structures 41, 51, 61, 71, are preferably perpendicular to the chessboard-like pattern, but other angles between a planar, flat level structure of a visual barrier and the surface of the chessboard-like pattern are also conceivable and suitable depending on the arrangement (cf even Figure 6b ).

Different shades of gray can be realized by suitably selecting the blackening and the density of the material changes. This is illustrated by the visual barrier 71 .

Figure 6b 12 also shows a section of a document body 1. In this embodiment, the checkerboard is produced by pre-printed colored areas 80, which are formed, for example, by the primary colors cyan 83, magenta 81, yellow 82 (C, M, Y). Here, too, the planar, flat level structures 41, 51, 61, 71, which are designed as visual barriers, cover depending on the viewing direction 140, 150, 160, 170 different color ranges. By way of example, the planar, even structures of the visibility barriers 41, 51 are not oriented perpendicularly, but at a different angle to the plane of the colored areas. As above to Figure 6a described, can also be in the embodiment of Figure 6b realize different shades of gray.

In addition to chessboard-like patterns, other patterns, e.g. a honeycomb structure or a line structure, can be advantageous. Several differently configured patterns can also be combined in one document body.

It will be appreciated by those skilled in the art that only exemplary exemplary document bodies are described herein. The individual features of the different embodiments can be used in combination to form complex security features. Thus document bodies can contain more or less colored areas. Furthermore, further transparent material layers can be arranged above or below the colored areas, in each case based on the one outer surface. In addition to the security feature described here, which is formed by the internal material changes produced by means of a laser, other security features and elements can be formed in the document bodies.

Reference List

1

document body

2

top

3

bottom

10

security document

12

an outside surface

13

opposite outer surface

15

surface normal

20

transparent volume area

21

yellow colored (transparent) area

22

cyan colored (transparent) area

23

magenta colored (transparent) area

30

opaque volume area

32

Top of the opaque volume area

41

(plane) flat plane structure

42

additional (plane) flat level structure

51

(plane) further flat plane structure

52

additional (plane) more flat level structure

61

plane flat plane structure

71

plane flat plane structure

80

colored areas

81

first colored areas

82

second colored areas

83

third colored areas

84

fourth colored areas

100

viewing direction dependent security feature

140

an excellent point of view

150

another excellent viewing direction

160

viewing direction

170

viewing direction

500

material changes

541

brightening material changes in the yellow colored area

542

brightening material changes in the cyan colored area

543

brightening material changes in the magenta colored area

551

Opaque material changes in the yellow colored area

552

Opaque material changes in the cyan colored area

553

Opaque material changes in the magenta colored area

Claims (13)

A security document (10) with a security feature that depends on the viewing direction, the security document (10) having a document body (1) with a transparent volume region (20) extending at least as far as an outer surface (12), in which the document body (1) is made of a transparent material is, inside which localized laser-induced material changes (500) are formed,
characterized in that
the laser-induced material changes (500) are formed at different distances in relation to the outer surface (12) in the transparent volume area (20). Security document (10) according to Claim 1, characterized in that at least a large number of the laser-induced material changes (500) span a planar or semi-planar flat level structure (41), the level structure strength of which is of the order of magnitude of the extent of the individual material changes ( 500) lies. The security document (10) according to claim 2, characterized in that at least one distinct viewing direction (140) corresponds to the one planar or semi-planar flat plane structure (41), wherein the at least one distinct viewing direction (140) is defined relative to the document body (1). , and of the one flat plane structure (41), at least in a section, only one plane structure strength can be detected when viewed from the distinguished viewing direction of the document body (1). The security document (10) according to Claim 2 or 3, characterized in that the at least one planar or semi-planar flat plane structure (41) differs, at least in one section, by a track curve of one section of the planar or semi-planar flat plane structure (41) with a track plane im Inside the volume region (20) and the at least one distinct viewing direction (140) corresponding to the at least one section can be approximated by the trace curve being extruded parallel to the one distinct viewing direction (140). The security document (10) according to any one of the preceding claims, characterized in that at least a further plurality of laser-induced material changes (500) span a further planar or semi-planar flat plane structure (51), the plane structure strength of which is of the order of magnitude of the extent of the further planar or semi-plane flat Level structure (51) spanning individual material changes (500) is located. The security document (10) according to Claim 5, characterized in that at least one further distinguished viewing direction (150) corresponds to the one further planar or semi-planar flat plane structure (51), the at least one further marked viewing direction (150) being relative to the document body (1 ) is defined, and of the one further planar or semi-planar flat plane structure (51) at least in one section only one plane structure strength can be detected when viewing the document body (1) from the one further marked viewing direction (150). The security document (10) according to one of Claims 5 or 6, characterized in that the at least one distinguished viewing direction (140) and the at least one further distinguished viewing direction (150) are different from one another and are not parallel to a surface normal of the outer surface of the document body (1 ) are oriented. The security document (10) according to any one of the preceding claims, characterized in that in the one transparent volume area (20) extending at least up to the one outer surface (12) or below the one transparent volume area extending at least up to the one outer surface (12). (20) and one or more colored areas (80, 81-84) are formed at a distance from the one outer surface (12), so that the one colored area (81) or at least one of the several colored areas (81-84 ) by the multitude of material changes (500) of the one planar or semi-planar flat plane structure (41) or another multitude of material changes (500) of the further planar or semi-plane flat plane structure (51) depending on the viewing direction (140, 150). The security document (10) according to any one of the preceding claims, characterized in that the one transparent volume area (20) extending at least as far as the one outer surface (12) comprises differently colored areas (21-23) and at least some of the laser-induced material changes (500 ) is formed in one or more of the differently colored areas (21-23) in order to thereby change the local color impression inside the security document (10). Security document (10) according to one of Claims 8 or 9, characterized in that the plurality of colored areas form a basic pattern and, relative thereto, the plurality of material changes (500) of the one planar or semi-planar flat plane structure (41) and/or the further plurality of Material changes (500) of the further planar or semi-planar flat plane structure (51) and/or at least one additional plurality of material changes of at least one additional planar or semi-planar flat plane structure are arranged, so that different patterns can be detected from different viewing directions, which differ from one another as a result, that different colored areas of the basic pattern are affected by the multitude of material changes of the one planar or semi-planar flat layer structure (41) and/or the further planar or semi-planar flat layer structure (51) and or one or more of the at least one additional planar or semi-planar flat planar structure covered and/or uncovered. Method for producing a security document body (1) of a security document (10) with a security feature dependent on the viewing direction, comprising the steps: Providing the document body (1) with a transparent volume region (20) extending at least up to one surface, in which the document body (1) is formed from a transparent material, Generating material changes (500) by means of a laser inside the transparent volume area (20), characterized in that the laser-induced material changes (500) at different distances are formed in the transparent volume region (20) in relation to the outer surface (12). Method according to Claim 11, characterized in that the material changes (500) are carried out by means of ultra-short laser pulses, the light of which is focused inside the document body (1) using optics which are separate from the document body (1) and have a numerical aperture NA>0.4 will. Method according to one of Claims 11 or 12, characterized in that the laser-induced material changes (500) are hollow volumes and/or discolorations.

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