EP3967510B1 - Security document with viewing direction-dependent safety feature - Google Patents

Description

The invention relates to a security document with a viewing direction-dependent security feature and a method for producing it. In particular, the invention relates to a security document with a document body which has a transparent volume region extending at least to a 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 that are intended to protect them against imitation and/or falsification. These features are referred to as security features because they protect such a security document against falsification and/or unauthorized production. 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 an effect that depends on the viewing direction. This means that the optical or visual capture of the security document provides different optical or visually perceptible views of the same surface of the security document from different viewing directions.

The EP 3 508 350 A1 describes the preamble of claim 1 or an information display medium that can improve the anti-counterfeiting effect. An information display medium includes a light reflecting layer made of a metal or a metal oxide and disposed partially or completely on a surface of a substrate, and the light reflecting layer includes a first region in which first information is represented by either an outline shape or an uneven area shape a combination of both are displayed, and a second information display area in which identification information is formed by partial material removal of the light reflection layer, the second information display area being set to partially or completely overlap with the light reflection layer where the first information is displayed in the first area become.

The EP 2 236 308 A1 concerns the use of secure identification documents and a method for securing such identification documents. The identification document consists of a body and at least one overlay covering at least one of the main surfaces of the body, said main surface bearing official personalization data, the document also comprising at least one transparent part and graphic anti-counterfeiting means making it possible to detect any attempt to prove fraudulent alteration or personalization of the document. The graphic anti-counterfeit means are characterized in that they are created three-dimensionally so that they extend from one side of the document to the opposite side through the thickness of the at least one transparent part of the body.

The EP 2 875 963 A1 concerns a security document, a production process and a verification process. What is described is a security document with a flat, extended document body which has an upper side and an opposite underside, the document body having a bending elasticity in relation to compressive forces that act on opposite points or side edges of the document body in relation to the upper side, with a Lens array is formed and inside the document body a first graphic information is stored relative to the lens array, which in a plan view along an excellent direction on the top of the document body while it is in a flat basic state in which no compressive forces act on the document body , can be graphically detected through the lens array, the excellent direction being defined relative to a reference plane in which the upper side is in the basic state of the document body, and in a curved state of the document body, in which compressive forces of predetermined strength are tangential in the reference plane on the Act on the document body in such a way that the document body bulges out of the reference plane in the area of the lens array, and the first information from the selected direction cannot be captured graphically or can only be captured graphically in a changed appearance.

A group of security features that show a viewing direction-dependent effect 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 the surface of a Lens-like structures are embossed on the document body. Due to refraction effects on these lens-like elements, irradiated laser light is focused inside the document body when the markings are formed and material changes are generally generated in the focus and in areas in front of or behind the focus of the beam path used for generation. As a rule, the material changes are discoloration. In particular, plastic layers are blackened to a greater or lesser extent. When viewing the security document, the blackening in focus is ideally only from the viewing direction through the Lens-like structure of the surface can be seen, which corresponds to the direction of irradiation of the light that was irradiated to produce the material changes. If the document body is viewed from a viewing direction other than the original direction of irradiation or generation, the material changes are not perceptible or are only noticeable in different ways.

A disadvantage of security elements of this type is that structures must be formed on the surface that are difficult to create and can also be affected and destroyed by environmental influences. Furthermore, the markings are all 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 by producing the document body from several layers, as is usual, in a lamination process and printing the information on one of the transparent layers inside instead be introduced with a laser. Basically, in the case of a CLI or MLI feature, the information is formed in relation to an outside of the document body in a narrowly limited distance range from this surface inside. 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 which, on the one hand, are easy to verify visually and, on the other hand, offer good protection against delamination and replacement of individual layers and against are well protected from external mechanical influences.

The invention is achieved by a security document with the features of patent claim 1 and a method with the features of patent claim 7. Advantageous embodiments of the invention result from the subclaims.

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 consist of different Layers of material that are laminated together, are formed, cannot be subsequently separated from one another and replaced and/or manipulated by others without this being noticeable in the security feature.

Definitions

Volume regions through which light can propagate for at least one wavelength range of the visible spectrum without significant diffuse scattering are considered transparent. Such an area can be colored. Imaging according to geometric optics can be carried out through a transparent area at least with light of a wavelength range. Clear window panes, for example, are made of transparent material in the sense described here. But clear tinted window panes are also transparent in the sense of the technical teaching described here.

A plane structure is a structure in three-dimensional space formed from a large number of material changes, which can be viewed as support points of a grid that spans a plane or surface. This means that a grid would be created that spans the surface or plane if neighboring material changes were connected via grid lines. Typically, the average distance between adjacent material changes will be less than ten times the extent of a single one of the material changes, more preferably less than five times the extent of a single one of the material changes, and most preferably less than two and a half times the extent of a single one of the material changes. 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 when connecting the support points with the neighboring support points must form a surface or plane, which may have a certain plane thickness or surface thickness, which is due to the fact that not all material changes lie in exactly one plane or surface.

A plane structure is flat if the structure created by the material changes has a small extent across the surface in relation to the extent of the surface itself. Preferably, the extent is the flat plane structure perpendicular to the surface limited to the extent of the individual material changes. However, the spanned flat level structure can also be designed as a multi-layer "grid structure", so that the flat level structure has a level structure thickness which 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 plane structure thickness is at least an order of magnitude smaller than the extent of the surface of the plane structure.

Plan is a plane structure if it can be viewed as a physical configuration of a part of a mathematical non-curved plane. The plane structure strength and "surface roughness" are neglected if neighboring material changes are not in one plane.

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

Level structures are referred to as partial plans in which there is a viewing direction in each point of the level structure, under which only the extent of the level structure thickness is shown when viewing the respective point of the level structure.

A planar flat plane structure can be conceptualized as an "extrusion body" which is formed by the material changes arranged along an elongated linear or strip-shaped structure being "extruded" along a spatial direction which 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 understood by the person skilled in the art that the laser markings are not introduced into the transparent volume area 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 viewing direction-dependent security feature is proposed, wherein the security document has 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 in the transparent volume region at different distances relative to the outer surface.

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 to an outer surface, in which the document body is formed from a transparent material; Generating material changes by means of a laser inside the transparent volume area, the laser-induced material changes being formed at different distances based on the outer surface in the transparent volume area.

The security feature is particularly easy to verify since, according to the invention, at least a large number of the laser-induced material changes span a flat or semi-plane flat plane structure, the plane structure thickness of which is in the order of magnitude of the extent of the individual material changes spanning the flat plane structure. The magnitude here means that the level structure strength can range from a simple extent of individual material changes to 10 to 15 times the extent of individual material changes. Overall, however, the flat 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 plane structure thickness is advantageously a multiple of the extent of the individual material changes spanning the flat plane structure and is advantageously less than 100 μm. In some embodiments, the plane structure strength corresponds to the extent of individual material changes. For all According to embodiments, if, for example, a layer inside such a document body is replaced or manipulated, this can be easily recognized by a lack or offset of material changes in the flat plane structure.

According to the invention, at least one excellent viewing direction corresponds to the one planar or semi-plane flat plane structure, the at least one excellent viewing direction being defined relative to the document body, and of the one plan or semi-plane flat plane structure, at least in a section, only one plane structure thickness of the flat plane structure when viewed can be detected from the one excellent viewing direction of the document body. Such a flat plane structure therefore has at least one section that loses its flat character from a viewing direction and appears as a narrow, more line-like marking. However, under other viewing directions, the flat 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.

If the flat plane structure is designed to be planar, then from the at least one excellent viewing direction, the entire flat plane structure formed can be seen as a straight, spatially limited marking, the extent of which transverse to the straight line corresponds to the thickness of the flat plane structure.

In addition to a plan design of the level structure, other forms can be imagined and implemented. For example, semi-plane, wave-shaped layer structures can be realized. Partially planar level structures, for example in the form of a cone shell or shapes similar to a Möbius strip, can also be realized. The shapes mentioned are exemplary and do not limit a further variety of shapes.

One embodiment provides that the at least one flat or semi-plane flat plane structure is at least in one section through a track curve of one section of the flat or semi-plane flat plane structure with a flat track plane inside the volume area and the at least one corresponding to the at least one section Excellent viewing direction can be approximated by the track curve being parallel to the one excellent viewing direction is “extruded” as explained above. The track plane can, for example, be a plane inside the transparent volume area that is oriented parallel to the outer surface. The intersection of the flat plane structure with the track plane creates track elements in sections that correspond to excellent viewing directions in order to reconstruct part of the flat plane structure by "extruding" the track section.

According to the invention, several flat or semi-plane flat plane structures designed separately from one another are included. According to the invention, it is therefore provided that at least a further plurality of laser-induced material changes span a further planar or semi-plane flat plane structure, the plane structure thickness of which is in the order of magnitude of the extent of the individual material changes spanning the further flat plane structure. This makes it possible to secure even larger areas based on the outer surface of the document body via the security feature by forming the different flat plane structures in different areas based on the outer surface of the document body inside the transparent volume area.

Furthermore, at least one further excellent viewing direction corresponds to the one further plan or semi-plane flat plane structure, the at least one further excellent viewing direction being defined relative to the document body, and of the one further plan or semi-plane flat plane structure, at least in one section, only one plane structure thickness at one Viewing the document body from another excellent viewing direction can be detected. The further flat plane structure can therefore also be seen as a trace at least in sections from one viewing direction, the further excellent viewing direction, whereas it can be seen as a surface formed on the inside from other viewing directions.

According to the invention, the at least one excellent viewing direction of the one planar or semi-plane flat plane structure and the at least one further excellent viewing direction of the at least one further plan or semi-plane flat plane structure are different from one another and thus characterize different viewing directions of the document body. So it's out of the one In the excellent viewing direction, at least a section of a flat or semi-plane flat plane structure can be seen as a narrow trace, while the flat extent of the other flat or semi-plane flat plane structure can be perceived. Conversely, from the further excellent viewing direction, the further flat or semi-plane flat plane structure can be perceived as a narrow track, at least in one section, and the one flat or semi-plane flat plane structure can be perceived as a surface formed in the transparent volume. By tilting the document body in such a way that the user alternately assumes one excellent viewing direction or another excellent viewing direction relative to the document body, this results in a clearly viewing direction-dependent effect occurring in the security document body.

Particularly preferably, the at least one excellent viewing direction and the at least one further excellent viewing direction are 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 thus viewed from the outer surface perpendicular to its outer surface, the one flat or semi-plane flat plane structure and the other flat or semi-plane flat plane structure, each of which is spanned by a large number of material changes, are each seen as being inclined relative to the surface surfaces extending into the volume can be seen. As with the other embodiments, this leads to a clearly different appearance from other known laser markings being visible inside transparent volume layers.

The material changes are carried out using ultra-short laser pulses, the light of which is focused inside the document body using optics that are designed separately from the document body and have a numerical aperture NA > 0.4. This strong focusing means that the material changes are locally limited and only occur in the focal area. In contrast to laser markings, which are carried out via refracting 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. However, with classic laser markings that cause discoloration, this is usually not the case and the extent transverse to the surface is significantly larger than parallel to the surface. Appearance forgeries through classic laser marking processes, even if the lens elements are only on the The external surface that is placed on the surface during production can therefore be easily distinguished from the new security feature. As a rule, these differences are noticeable with the naked eye.

The fact that the material changes partially cover a volume area behind it and/or at least limit or modify its perception can be exploited in embodiments to create 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 region which extends at least to an outer surface or below the one transparent volume region which extends at least to the one outer surface and in each case at a distance from the one outer surface, so that an obscuration 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-plane flat plane structure or further multitude of material changes of the another plan or semiplane flat plane structure varies depending on the viewing direction. If, for example, the colored areas are formed 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 produce a different colored impression on a viewer or a color analysis can be on the different sides of a track be arranged, which consists of the contact trace of a plane in which the at least one flat or semi-plane flat plane structure lies, with the plane in which the paint is applied, or a further trace, which consists of the touch trace of a further plane in which the Another flat or semi-plane flat layer structure lies with the level of the paint application. If different color areas are formed on the different sides of the track, the color changes when the viewing direction changes. In some viewing directions, the colored area on one side of the track is at least partially obscured by the flat plane structure. From other viewing directions, however, the flat layer structure obscures the paint application on the other side of the track. This creates a color-shifting 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 in a checkerboard manner, flat plane structures are formed, so that by deliberately covering individual areas with planar or semi-plane flat plane structures from a variety of material changes, the information can be recorded in the form of patterns that emerge from the basic pattern through the complete or partial concealment of individual colored areas. In one embodiment it is therefore provided that the plurality of colored areas form a basic pattern and, relative to this, the plurality of material changes of the one flat or semi-plane flat plane structure and/or the further plurality of material changes of the further flat or semi-plane flat plane structure and/or at least one additional A large number of material changes of at least one additional flat or semi-plane flat plane structure are arranged, so that different patterns can be detected from different viewing directions, which differ from one another in that different of the colored areas of the basic pattern are caused by the large number of material changes of the flat or semi-plane flat plane structure and / or the further flat or semi-plane flat level structure and/or one or more of the at least one additional flat or semi-plane flat level structure are covered and/or uncovered.

In yet other embodiments, it is provided that the transparent volume region extending at least to 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 improve the local color impression inside the change the 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 one on top of the other relative to a vertical view of the one outer surface. These different areas can be created, for example, by transparent, colored films that are laminated together to form the document body. An outer or uppermost area can also be colorless, ie not colored.

The laser-induced material changes are particularly preferably formed as cavities or small hollow volumes. This allows targeted color impressions to be created through the laser-induced material changes arranged in the different levels.

Such laser-induced material changes can be generated using ultra-short laser pulses, the light of which is focused inside the document body using optics that are designed separately from the document body and have a numerical aperture NA > 0.4. For some materials, such a targeted local modification can be achieved with 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 alternatively or additionally be produced, which, however, are also produced in a sharply localized manner using ultra-short laser pulses and high focusing with a numerical aperture > 0.4.

The material changes, which are formed in the clear, uncolored transparent material and which together form a plane structure, can also advantageously be designed as cavities, which are optically perceptible due to a difference in refractive index on the boundary surfaces of the cavities and the resulting interactions with light. Even in clear material, the material changes can alternatively or additionally be formed via sharply defined, localized blackening or gray discoloration.

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. Show here:

Fig. 1

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

Fig. 2a

a schematic isometric view of the document body Fig. 1 , viewed from an excellent viewing angle;

Fig. 2b

another schematic isometric view of the document body Fig. 1 , viewed from another excellent perspective;

Fig. 3

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

Fig. 4a

a schematic isometric view of the document body 1 Fig. 3 , viewed from an excellent viewing angle;

Fig. 4b

another isometric view of the document body 1 Fig. 3 , viewed from another excellent perspective;

Fig. 5

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

Fig. 6a

a schematic isometric view of a document body, in the interior of which a checkerboard-like light-dark pattern is formed with flat plane structures designed as visual barriers; and

Fig. 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 flat plane structures designed as visual barriers.

In Fig. 1 A document body 1 of a security document 10 is shown schematically. The same reference numerals are used for the same technical features in all figures. It will be understood by those skilled in the art that highly simplified embodiments are described here. The in Fig. 1 Document body 1 shown can contain a variety of further security features and security elements that are not shown here. In addition, the proportions of the individual features and elements shown are not realistically represented.

The document body 1 has a top 2 and an opposite bottom 3. Here in between the document body is formed from a completely transparent volume area 20. This therefore extends at least to one outer surface 12, which is the top 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 inside the transparent volume region 20, which extends at least to one outer surface 12, with the aid of a large number of microscopic material changes 500 generated by a laser. The material changes are measured at different distances perpendicular to the outer surface 12 in the interior of the transparent volume region 20. This means that at least two material changes can always be found that are at different distances from the outer surface. When we talk about the distance to the outer surface here, this is measured parallel to the surface normal 15 of the outer surface 12.

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

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

A flat plane structure is defined as a structure that locally only has a small extent perpendicular to the flat extent. This expansion is over the surface extent 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.

An excellent viewing direction 140 is linked to the one planar flat plane structure 41, which has the angle α relative 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 one excellent viewing direction 140, only its level structure thickness can be detected from the one flat level structure 41. 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 areal extent of the flat plane structure 41 can be seen.

This is exemplary Fig. 2a and Fig. 2b shown, where Fig. 2a the isometric view of a view from one excellent viewing direction 140 and the Fig. 2b represent a view of the document body 1 from a further excellent viewing direction 150.

The further excellent viewing direction 150 corresponds to a further flat plane structure 51 spanned from a further large number of material changes 500. In the illustrated embodiment, this further flat plane structure 51 is also flat and oriented at an angle of inclination β relative to the surface normal 15 of the outer surface 12. The further excellent viewing direction 150 is oriented parallel to the further flat plane structure 51. Under the further excellent viewing direction 150, the further flat plane structure 51 appears as a straight line or route 151 (compare Fig. 2b ). On the other hand, the surface extent of the further flat plane structure 51 is shown in the view of Fig. 2a , which corresponds to the one excellent viewing direction 140, can be clearly seen.

The document body 1 after Fig. 1 contains, in addition to the one flat plane structure 41, an additional flat plane structure 42 oriented parallel to this, which is formed from a variety of material changes, as well as an additional 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 the one excellent viewing direction 140 one takes the view of Fig. 2a true, in which the one flat plane structure 41 and the additional flat plane structure 42 are each perceptible as narrow straight lines 141, 142 and the further flat plane structure 51 and the additional further flat plane structure 52 are each perceptible as surfaces. This is reversed when the document body 1 is perceived under the further excellent viewing direction 150, as in Fig. 2b is shown. In this case, the areal extent of the one flat plane structure 41 and the additional flat plane 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 Fig. 3 a further document body 1' is shown, which is different from the document body 1 Fig. 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 embodiment shown, the colored areas 80 are designed like stripes, alternating first colored areas 81 and second colored areas 82 are formed, for example by a print. The strip-like areas are aligned parallel to the longitudinal extents of the flat plane structures 41, 42 and 51, 52, respectively. This means that in the case of a planar, flat plane structure 41, 42 or 51, 52, which is viewed from an assigned, excellent viewing direction 140 or 150 and can be perceived as a straight line 141, 142 or 151, 152 (compare 4a and 4b ), this line 141, 142; 151, 152 preferably separates a first colored area from a second colored area. Thus, for example, one colored area 81 is perceived on one side of the line 141 when viewed under the excellent viewing direction 140 and the other colored area 82 is perceived on the other side. If you change the viewing direction, either the one colored area 81 or the other colored area 82 is at least partially covered by the flat flat plane structure 41 or at least changed with regard to the color perception.

In Fig. 4a and Fig. 4b the views of the document body 1′ are shown accordingly for the one excellent viewing direction 140 and the another excellent viewing direction 150. The effect described is clearly visible. While in Fig. 4a the one colored area 81 on the left can be perceived unhindered and uncovered by the flat plane structure 41 and the second colored area 82 immediately to the right of the one flat plane structure 41 can also be detected undisturbed, a right part of this second colored area 82 is partly through the additional flat level structure 52 partially hidden. 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 Fig. 4b illustrated view, which shows the perception for viewing from the further excellent 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 stretches 151, 152. The first colored area 81 is almost completely covered by the flat plane structure 41. The second colored area 82, however, like the third colored area 83, can be seen almost undisturbed and uncovered. The fourth colored area 84, however, is covered by the additional level structure 42.

It will be clear to the person skilled in the art that targeted color-shifting effects of various kinds can be created in this way. The level 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 one direction.

In Fig. 5 Another embodiment is shown. In this case, the document body 1 comprises three differently colored areas 21-23. In the embodiment shown, these are each designed as material layers of equal thickness, oriented parallel to the outer surface 12. By way of example, the uppermost colored transparent area 21 is yellow, the middle colored transparent area 22 is cyan and the lowest colored transparent area 23 is magenta.

The viewing direction-dependent security feature 100 is formed by a large number of material changes 500 in the interior of the transparent volume area 20, i.e. in the different colored transparent areas 21-23. There are brightening material changes 541 in the yellow colored area 21 (crossed hatching), brightening material changes 542 in the green colored area 22 (hatching running from top left to bottom right) and brightening 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 circles. These brightening material changes 541 to 543 can also be arranged with respect to the 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 brightening material changes in the differently colored areas together form a planar, flat plane structure 41. In addition, in the embodiment shown 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 in squares. Their color is indicated by hatching. These material changes 551 to 553 can together, for example, span a further planar plane structure 51, which corresponds to an excellent further viewing direction 150, so that the various opaque discoloring material changes 551 - 553 are at least partially arranged one behind the other with respect to the one further excellent viewing direction 150. However, other arrangements of the brightening material changes 541 - 543 or opaque discoloring material changes 551 - 553 in the different colored areas of the transparent volume area 20 are also possible, 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 via hatching.

The brightening material changes are preferably formed by cavities that are formed in the individual colored areas by the highly 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.

For focusing, optics are used that have a numerical aperture NA of 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 focusing together with the short pulse durations enables the precise and targeted localization of material changes. Furthermore, the distance between the material change and the outer surface can be specifically adjusted and varied.

Figure 6a shows a section of a document body 1, in which a transparent window element is formed in the form of a transparent volume area 20. Inside the document body 20, colored areas 80 are formed in one plane, for example in the form of a checkerboard-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 surface 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. for example above the checkerboard-like pattern, planar flat plane structures 41, 51, 61, 71, each formed from a large number of material changes, are positioned and designed as visual barriers. The structure 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. The surface density of the material changes can be varied from level structure to level structure.

The dimensions of the planar, flat plane structures are preferably adapted to the dimensions of the colored areas 80 arranged in a checkerboard manner. Depending on a respective viewing direction 140, 150, 160, 170 (ie an angle relative to the top 2) at which the colored areas 80 are detected, different colored areas (80) are visible to the viewer (the detecting one). camera) covered. Different patterns can be detected. Information (images, texts, symbols) can be encoded here.

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

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

Different shades of gray can be achieved through a suitable choice of blackening and the density of the material changes. This is illustrated by the visual barrier 71.

Fig. 6b also shows the section of a document body 1. In this embodiment, the chessboard is created 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 flat plane structures 41, 51, 61, 71 designed as visual barriers cover 140, 150, 160, depending on the viewing direction. 170 different color ranges. For example, the flat, flat structures of the visual barriers 41, 51 are not oriented vertically, but at a different angle to the plane of the colored areas. As above Fig. 6a described, can also be used in the embodiment of Fig 6b Realize different shades of gray.

In addition to checkerboard-like patterns, other patterns, such as a honeycomb structure or a line structure, can be advantageous. Several differently designed patterns can also be combined in one document body.

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

Reference symbol list

1

Document body

2

Top

3

bottom

10

Security document

12

an outdoor surface

13

opposite external surface

15

Surface normals

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 level structure

42

additional (plane) flat layer structure

51

(plane) further flat level structure

52

additional (plane) further flat level structure

61

plan flat level structure

71

plan flat level structure

80

colored areas

81

first colored areas

82

second colored areas

83

third colored areas

84

fourth colored areas

100

Security feature dependent on the viewing direction

140

an excellent perspective

150

another excellent perspective

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 discoloring material changes in the cyan colored area

553

Opaque discoloring material changes in the magenta colored area

Claims (9)

1. A security document (10) with viewing direction-dependent safety feature, the security document (10) having a document body (1) with a transparent volume region (20) extending at least up to an outer surface (12), in which the document body (1) is formed from a transparent material, in the interior of which localized laser-induced material changes (500) are formed,

   wherein the laser-induced material changes (500) are formed at different distances relative to the outer surface (12) in the transparent volume region (20), wherein at least a plurality of the laser-induced material changes (500) span a planar or semi-planar flat plane structure (41), the plane structure thickness of which is in the order of magnitude of the extent of the individual material changes (500) spanning the flat plane structure (41), wherein at least one distinctive viewing direction (140) corresponds with the one planar or semi-planar flat plane structure (41), wherein the at least one distinctive viewing direction (140) is defined relative to the document body (1), and of which one flat plane structure (41) only a plane structure thickness is detectable at least in a section when viewed from the distinctive viewing direction of the document body (1), but, from other viewing directions, the laminar nature of the planar or semi-planar flat plane structure (41) is recognizable,

   wherein at least a further plurality of the laser-induced material changes (500) span a further planar or semi-planar flat plane structure (51), the plane structure thickness of which is in the order of magnitude of the extent of the individual material changes (500) spanning the further planar or semi-planar flat plane structure (51) and at least one further distinctive viewing direction (150) corresponds with the one further planar or semi-planar flat plane structure (51), the at least one further distinctive viewing direction (150) being defined relative to the document body (1), and of which one further planar or semi-planar flat plane structure (51) only a plane structure thickness is detectable at least in a section when viewing the document body (1) from the further distinctive viewing direction (150), but, from other viewing directions, the laminar nature of the further planar or semi-planar flat plane structure (51) is recognizable,

   characterized in that the at least one distinctive viewing direction (140) and the at least one further distinctive viewing direction (150) are different from one another.
2. The security document (10) according to claim 1, characterized in that the at least one distinctive viewing direction (140) and the at least one further distinctive viewing direction (150) are each not oriented parallel to a surface normal of the outer surface (12) of the document body (1).
3. The security document (10) according to claim 1 or 2, characterized in that the at least one planar or semi-planar flat plane structure (41) can be approximated, at least in the one section, by a trace curve of the one portion of the planar or semi-planar flat plane structure (41) with a trace plane inside the volume region (20) and the at least one distinctive viewing direction (140) corresponding to the at least one section, wherein the trace plane may be created by extruding the trace curve parallel to the one distinctive viewing direction (140) .
4. The security document (10) according to any one of the preceding claims, characterized in that one or several colored areas (80, 81-84) are formed in the one transparent volume region (20) extending at least up to the one outer surface (12) or below the one transparent volume region (20) extending at least up to the one outer surface (12), and spaced from the one outer surface (12), respectively, so that a cover of the one colored area (81) or at least one of the several colored areas (81-84) varies due to the plurality of material changes (500) of the one planar or semi-planar flat plane structure (41) or a further plurality of material changes (500) of the further planar or semi-planar flat plane structure (51), each depending on the viewing direction (140, 150).
5. The security document (10) according to any one of the preceding claims, characterized in that the transparent volume region (20) extending at least up to the one outer surface (12) comprises differently colored regions (21-23), and at least a part of the laser-induced material changes (500) is formed in one or several of the differently colored regions (21-23) to thereby change the local color impression inside the security document (10).
6. The security document (10) according to any one of claims 4 or 5, characterized in that the several colored regions 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 in different viewing directions, which differ from one another in that different ones of the colored regions of the basic pattern are covered and/or not covered by the plurality of material changes of the one planar or semi-planar flat plane structure (41) and/or the further planar or semi-planar flat plane structure (51) and/or one or several of the at least one additional planar or semi-planar flat plane structure.
7. A method of creating a security document body (1) of a security document (10) with a viewing direction-dependent safety feature, comprising the steps of:

   providing the document body (1) with a transparent volume region (20) extending at least up to an outer surface, in which the document body (1) is formed from a transparent material,

   creating material changes (500) by means of a laser in the interior of the transparent volume region (20),

   wherein the laser-induced material changes (500) are formed at different distances relative to the outer surface (12) in the transparent volume region (20), so that at least a plurality of the laser-induced material changes (500) span a planar or semi-planar flat plane structure (41), the plane structure thickness of which is in the order of magnitude of the extent of the individual material changes (500) spanning the flat plane structure (41), wherein at least one distinctive viewing direction (140) corresponds with the one planar or semi-planar flat plane structure (41), wherein the at least one distinctive viewing direction (140) is defined relative to the document body (1), and of which one flat plane structure (41) only one plane structure thickness is detectable at least in a section when viewed from the distinctive viewing direction of the document body (1), but, from other viewing directions, the laminar nature of the planar or semi-planar flat plane structure (41) is recognizable,

   wherein at least a further plurality of the laser-induced material changes (500) span a further planar or semi-planar flat plane structure (51), the plane structure thickness of which is in the order of magnitude of the extent of the individual material changes (500) spanning the further planar or semi-planar flat plane structure (51) and at least one further distinctive viewing direction (150) corresponds with the one further planar or semi-planar flat plane structure (51), the at least one further distinctive viewing direction (150) being defined relative to the document body (1), and of which one further planar or semi-planar flat plane structure (51) only one plane structure thickness is detectable at least in a section when viewing the document body (1) from a further distinctive viewing direction (150), but, from other viewing directions, the laminar nature of the further planar or semi-planar flat plane structure (51) is recognizable,

   characterized in that the at least one distinctive viewing direction (140) and the at least one further distinctive viewing direction (150) are different from one another.
8. The method according to claim 7, characterized in that the material changes (500) are carried out by means of ultrashort laser pulses, the light of which is focused with an optical system formed separately from the document body (1), having a numerical aperture NA>0.4 in the interior of the document body (1) .
9. The method according to any one of the claims 7 or 8, characterized in that the laser-induced material changes (500) are hollow volumes and/or discolorations.

Images