EP4151427B1 - Verification method for a security element with a window jib - Google Patents

Description

The invention relates to verification methods for a security element with a security element body in which a window region is formed. The security element can be a semi-finished product for the production of security documents or a security document itself.

A feature that is intended to prevent imitation, falsification, unauthorized production and/or to guarantee the authenticity and integrity of the object is referred to as a security feature. A physical object that has such a feature is referred to as a security element. Typical security elements are, for example, holograms, security threads, but also complete security documents or security document blanks.

For a class of security features and security elements, it is intended to be checked and/or verified optically, i.e. by means of a visual inspection, the capture of images and their evaluation and/or other optical methods. Different optical features can be used and/or checked for this purpose.

One such optical feature is, for example, the ability to transmit light. Materials through which light can pass almost unhindered, such as clear window panes, are referred to as transparent in the context of what is described here. This means that images are possible through the material in accordance with geometric optics. This may be limited to a certain wavelength range of the spectral range visible to humans. This is the case, for example, with colored clear glass or plastic.

Material that has a high transmission of light but diffuses it inside is referred to as translucent.

In the area of security documents, printed, filled plastic cards are generally referred to as opaque. Nevertheless, even such objects usually exhibit a certain transmission of light when viewed in front of a light source so that the light source is behind the security element in the viewing direction.

In the context of what is described here, a distinction is made between transparent material and non-transparent material, which includes both opaque and translucent material.

Modern security documents that have one or more non-transparent material layers and/or prints sometimes have a so-called window in which the material is completely transparent from the top to the bottom. Markings that have been introduced, for example in the form of local blackening by laser inscription and a non-full-surface print of individual alphanumeric characters or pixels inside, do not fundamentally change the fact that it is a window. However, overprinting of volume-transparent material with non-transparent material or covering with non-transparent material layers means that the corresponding covered or overprinted area is regarded as a non-transparent area of the corresponding security element.

An example of a security document with a window area can be found in the EN 10 2016 203 609 A1 described.

EP 2 384 901 A1 describes a substrate for the production of value documents, comprising a first layer with a first transmittance, which has at least one recess in the region of which the first layer has a second transmittance which is greater than the first transmittance, wherein an opaque layer is applied to a rear side and/or to a front side of the substrate, which has a third transmittance which is smaller than the second transmittance. Corresponding value documents are also described.

US$4,710,614 describes a security document comprising a substrate containing at least one optical fiber, at least one end of which is flush with a surface of the substrate to enable authentication of the document by a test based on exposing the document to a source of electromagnetic radiation and simultaneously observing the radiation transmitted to both ends of the optical fiber. The optical fiber has a transparent coating and is located within the substrate at a depth of at least one surface of the substrate that is not greater than the penetration depth of electromagnetic radiation into the substrate. The radiation that penetrates the substrate to the optical fiber is captured in the optical fiber and transmitted to at least one end where it is observed to authenticate the document.

WO 2019/077316 A1 describes a security document having a window area and a non-window area. The window area is of less opacity than the non-window area. The security document comprises a transparent polymer layer at least in the window area of the security document, and the transparent polymer layer comprises an internal laser marking therein having an optical effect.

WO 2008/031170 A1 describes a security document and a method of making a security document in which a radiation-curable ink is applied to at least one side of a substrate containing at least one region of transparent plastic material forming a window or half-window region. The ink is embossed while soft and cured with radiation to form an embossed security device within the window or half-window region comprising one or more diffractive structures, a lens structure or other security elements having a relief structure.

In addition to very complex security features that require a lot of effort for verification, there is always a need to integrate security features that are easy to check into security elements. The invention is therefore based on the object of creating a method for verifying security documents with a window area that is easy to verify but not easy to replicate.

The invention is achieved by a verification method having the features of patent claim 1. Advantageous embodiments of the invention emerge from the subclaims.

Basic idea of the invention

The invention is based on the general idea of creating a volume area made of transparent material inside the security element, which on the one hand forms a volume area from the top to an opposite bottom of the security element body extending window area, but between the top and the opposite bottom side, has an extension in cross section in the interior that is larger than the cross-sectional areas of the window area of the top and bottom, which are designed to be flush with one another. This makes it possible for light that passes through the window area to partially reach that area, referred to here as the window boom, which is covered translucently on the top and bottom, so that this transparent area is not visible in plan view.

A top view refers to an observation and/or the capture of an image in which illumination and capture take place from the same side of the security element. A transmitted-light observation, on the other hand, is an observation or capture of an image of the security element in which the light source is on the side of the security element facing the capture. In a transmitted-light observation, light is thus irradiated onto the surface facing away from the observer or the optical detection device and the light that is transmitted through the security element body is detected. Because the security element body in the area of the window boom comprises transparent material, the transmission through the security element body in the area of the window boom is increased compared to other areas, if any transmission of light through the security element body takes place at all. These statements also apply if the window area is covered during observation, so that no light inside the security element body can reach the window boom through the window area. If light is additionally or simultaneously irradiated through the window area, the window boom becomes even more prominent under suitable lighting and viewing directions, i.e. as a contrast difference in the security element body in the window boom area relative to the other non-transparent areas adjacent to the window area and/or the window boom area.

Definitions

The window area is the area on a surface of the security element body through which it is possible to see through the security element body, through the transparent material inside to the opposite side. Areas where this is not possible are called non-transparent areas of the The non-transparent area under which the window boom, ie transparent material connected to the see-through window, is located is called the boom area.

A transparent material is a material which is clear in volume, possibly coloured, but through which an image can be projected according to geometric optics using light of at least one wavelength in the visible, i.e. human-perceptible, wavelength range.

Through a window region, imaging according to geometric optics is thus possible at least for light of some wavelengths in the visible wavelength range if the window region is clear and colored, or for all wavelengths of the visible wavelength range if the transparent material forming the window region is not colored.

The transmission of light through a material layer or through a body is the process of light passing through or penetrating the material layer or the body, whereby the light can be scattered in the material layer or the body in the sense of classical optics.

The transmittance of a material layer or a body is the ratio of the intensity of the light transmitted through the material layer or body to the intensity of the light radiated onto the material layer or body. The term transmission is sometimes used as a synonym for the transmittance when the process of transmission is considered a measurable quantity.

Preferred embodiments

First, the security element and the method for producing security elements for which the verification method is suitable are described. The verification method is created in particular for a security element with a security element body which has a window region in which the material of the security element body is transparent between a top side and a bottom side, wherein the window region is surrounded and delimited all around by a non-transparent region of the security element body, wherein the Window region merges into a transparent window boom which extends into the non-transparent region, wherein the window boom is, however, completely covered in a non-transparent manner both towards the top and towards the bottom of the security element body. Furthermore, a method is provided for producing a security element which comprises a security element body with a window region extending from a top to a bottom, which is made of transparent material and merges into a window boom, the transparent material of which is completely covered in a non-transparent manner towards the top and towards the bottom, comprising: providing a core layer which is non-transparent in at least one surface section; making a recess in the core layer within the non-transparent surface section so that the recess is enclosed all around by a non-transparent part of the surface section; inserting transparent material into the recess; covering a boom section of the recess towards the top and towards the bottom in a non-transparent manner and introducing heat in order to form the security element body. The core layer itself can consist of a plastic material or can be a composite of several material layers into which, for example, other elements and security features are integrated.

It is therefore particularly preferred that the security element body has at least one non-transparent core layer with a recess which encloses the window area but is larger than the window area. In the finished security element body, the volume-transparent material of the window area also extends into a so-called window boom section of the recess in the core layer. This window boom area is completely covered and non-transparent on both the top and bottom of the security element body. The contour of the recess can partially be the outer contour of the window area, but is "larger" than the window area in at least one area.

A good and simple covering of the window boom on the top and/or on the bottom is achieved with an embodiment in which the window boom is covered on the top by an upper covering layer that is not transparent in volume and/or on the bottom by a lower covering layer that is not transparent in volume. The covering layer here is a self-supporting layer before being connected to the core layer and the material of the window boom. A pure printing layer made of ink or printing ink that is not independently load-bearing is not considered a covering layer within the meaning of the description here.

In other security elements, it can be provided that the window boom is covered on the top by a non-transparent upper coating and/or on the bottom by a non-transparent lower coating. Coatings can be applied, for example, by vapor deposition or by any printing process. For example, the covering can be done by an upper cover print or a lower cover print. In this case, the cover prints or the cover coatings are aligned with one another at a boundary line between the window area and the window boom. This means that when viewed vertically, or if the boundaries of the window area are otherwise aligned with respect to another preferred direction, the cover coatings are aligned with one another with respect to the normal or the other designated direction. When looking at the window area, the window boom can therefore only be recognized if part of the inner wall is transparent and not opaque. The same applies to the upper and lower cover layers, which are also aligned at the boundary line between the window area and the cantilever area with respect to the surface normal or a preferred direction with respect to which the boundary of the window area is aligned.

1. (a) zunächst ein erster Aussparungsabschnitt ausgebildet wird, der den Fensterauslegerabschnitt und ein Teil des Fensterbereichs umfasst,
2. (b) in den ersten Aussparungsabschnitt transparentes Material eingefügt wird, welches den Fensterauslegerabschnitt ausfüllt und eine Grenzlinie zwischen dem Fensterauslegerabschnitt und dem Fensterbereich vollständig überdeckt, und
3. (c) der Fensterauslegerabschnitt mindestens zu der Oberseite durch eine im Bereich des Fensterauslegerabschnitts nichttransparente obere Abdeckschicht und/oder an der Unterseite durch eine im Bereich des Fensterauslegerabschnitts nichttransparente untere Abdeckschicht abgedeckt wird, und
4. (d) die Kernschicht das eingefüllte transparente Material und die obere Abdeckschicht und/oder die untere Abdeckschicht punktuell miteinander verbunden werden, und
5. (e) anschließend die Aussparung der Kernschicht erweitert wird, sodass die Kernschicht im Fensterbereich der Aussparung frei von Material ist, wobei zeitgleich in die obere Abdeckschicht und/oder die untere Abdeckschicht ebenfalls Aussparungen eingebracht werden, die mit dem Fensterbereich der Aussparung in der Kernschicht fluchten, und
6. (f) Einbringen von transparentem Material zum bündigen Verfüllen der Aussparung.

In order to produce such a security element body, one embodiment provides that the introduction of the recess into the core layer and the filling with transparent material are each carried out in several processes or process steps, which include

1. (a) firstly, a first recess portion is formed which comprises the window boom portion and a part of the window area,
2. (b) transparent material is inserted into the first recess portion, which material fills the window boom portion and completely covers a boundary line between the window boom portion and the window area, and
3. (c) the window boom section is covered at least on the upper side by an upper covering layer which is non-transparent in the region of the window boom section and/or on the underside by a lower covering layer which is non-transparent in the region of the window boom section, and
4. (d) the core layer, the filled transparent material and the upper cover layer and/or the lower cover layer are connected to each other at certain points, and
5. (e) the recess of the core layer is then widened so that the core layer is free of material in the window area of the recess, whereby at the same time recesses are also made in the upper cover layer and/or the lower cover layer which are aligned with the window area of the recess in the core layer, and
6. (f) Insertion of transparent material to fill the recess flush.

This manufacturing process ensures that the non-transparent material layers that border the window area all the way around, for example the upper cover layer and/or the lower cover layer, have the same recess cross-section as the window area of the core layer. In addition, a good, secure connection is achieved to the transparent material of the window boom, which is initially introduced in such a way that it partially protrudes into the window area. When the core layer recess is expanded, not only the non-transparent material of the core layer but also that part of the transparent material of the boom section that protrudes beyond the boundary lines into the window area is removed from the window area, so that an optimal connection is created between the transparent material of the boom section and the transparent material located in the window area and inserted into it.

The introduction of the transparent material in process step (b) into the boom section is preferably carried out by means of a one-piece boom insert. In addition or alternatively, the transparent material is inserted in process step (f) by means of a one-piece window plug. In both cases, it is ensured that a reliable filling of the corresponding recess or a section/area can be carried out in a simple manner in the former case of the boom section and in the latter case of the window area. In particular, if the security element or the security element body is a lamination body which consists of more than the core layer and optionally an upper and/or lower cover layer, preferred embodiments provide that the core layer is covered with one or more further layers on the top or bottom before and/or after process step (c) and that process steps (d), (e) and (f) are carried out in the same way as for the upper cover layer and/or the lower cover layer. Further layers can thus be stacked on top of each other and connected to each other at certain points in order to provide them with the recess for the window area at the same time as the other layers. This is preferably done in a punching process.

In a preferred embodiment, recesses are not made parallel to the surface normal of the respective layers, but at an angle. This makes it possible to ensure that inserted transparent material pieces, such as the cantilever insert or the window plug, are held in place despite gravity when they are joined together in the respective layers, whose surfaces are oriented parallel to the earth's surface, for example. This makes handling easier.

Even more preferably, the material processing is carried out in such a way that the recesses created have beveled side walls, for example, side walls that taper conically along the direction of insertion transversely to the surface of the material layer. Such recesses with side or boundary walls that are beveled relative to a surface normal of the material layer or the top material layer in the case of several material layers stacked on top of one another and/or that taper along the depth of the recess can be produced using laser processing or water jet techniques. Accordingly adapted pieces of material that are inserted can thus be optimally held in the recesses during production. It goes without saying that the inserted pieces of material, such as the cantilever insert or the window plug, have correspondingly adapted beveled outer walls or walls that taper along their material thickness, so that an optimal form fit takes place when inserted into the recesses formed. Pieces of material to be inserted can, for example, be designed as injection molded parts.

Pieces of material that are inserted into recesses with sloping or funnel-shaped side surfaces do not usually have to be secured by stapling (for example, of adjacent layers to the layer containing the recess or to the layer into which they are inserted) and are only integrated into the document body in a final high-pressure, high-temperature lamination process.

The individual components are preferably joined together to form the lamination body by applying heat and applying pressure with a lamination press in order to bond the transparent material to the core layer and the upper cover layer and/or the lower cover layer to form the security element body. If additional material layers are present, these are also connected to form the security element body in this lamination step in the lamination press.

Particularly preferably, the contours of the recesses in the upper cover layer, the lower cover layer and the core layer, which define the window area, are coordinated with one another in such a way that in at least one contour section in which there is no window boom area adjacent to the window area, at every point of an edge of the recess in the upper cover layer there is a straight line to a corresponding point on an edge of the lower cover layer, the course of which coincides with the contour of the core section. In this contour section, the recesses are aligned with one another, regardless of whether the outer contour of the transparent window area in the contour section is perpendicular to the outer surface of the security element body, oblique, conical, tapers or widens from the top of the security document body to a bottom. This orientation can also be different in subsections of the at least one contour section. For verification, it is crucial that the alignment of the upper cover layer with the core layer and with the lower cover layer along the contour section can be checked at every point of the at least one contour section.

Preferably, there is a point in the transparent window area relative to which this at least one contour section covers an angular range of more than 180°, more preferably more than 210°, even more preferably more than 225° of the contour of the window area.

Particularly preferably, there is only one contour section in which there is no window boom area next to the window area. This contour section, supplemented by a transition section, results in the circumferential contour of the window area in such a preferred embodiment. The transition section is that section of the window contour in which the transparent material of the window area merges into the window boom area. Preferably, there is therefore only one transition section in the contour of the window area. The length of the transition section of the circumferential contour of the window area is preferably less than a quarter of the length of the entire circumferential contour of the window area.

The security element body can be a semi-finished product or a finished security document. If this is manufactured as a semi-finished product, it is preferred that one or more additional layers that are transparent in volume are applied to the top and/or bottom, which serve as protective layers or contain further security features, such as a hologram or similar.

An inventive verification of one of the described security elements with a window area that merges into a hidden window boom, for example a security element designed as a security document, is carried out according to one embodiment of a verification method in that verification light is shined into the window area of the security element, at least one image of the top or bottom is captured, which includes at least one area next to the window area, and the image is examined for brightness differences in the area next to the window area, wherein the security element is classified as genuine if an area with increased brightness is found that borders the window area and the verification decision is output. The output can be in the form of a signal, for example. The signal can be used, for example, to control an access device such as a door lock or a turnstile. The verification light can be, for example, the light of a flashlight or something similar.

According to the invention, a reference image of the corresponding top or bottom side is recorded, while no verification light, ie preferably no light at all, is irradiated into the window area or alternatively no light is irradiated into the window area in addition to the ambient light, ie only ambient light is incident, and when evaluating the at least one image, a difference is first formed with the reference image and the brightness differences are determined in the difference image, wherein the security element is only classified as genuine if an area with increased brightness is found in the difference image that borders the window area.

In one embodiment, the image is captured from the side from which the verification light is irradiated. This makes it possible to reliably distinguish simple transmitted light effects, which are due to the absorption of a security element varying over the surface, from the effect caused by a window boom.

In alternative embodiments, the image is captured on the side of the security element that is opposite the side from which the verification light is irradiated. If the verification light is irradiated from the top, the image is captured from the bottom and vice versa. Here, too, a reference image can be captured and included in the evaluation.

A further development analyses the shape of the area with increased brightness and compares it with predefined shapes. If the shape matches a predefined shape, the security element is classified as genuine, otherwise as not genuine. In a further development, security elements can be differentiated into groups or classes based on their match with one of the predefined shapes and assigned to these.

If the at least one image is captured from the side opposite the side from which the verification light is irradiated, if a light cone of the verification light or an irradiation area of the verification light covers the contour section of the window area completely or in sections, it can be checked in the image whether the recesses of the core layer and the cover layers are aligned with one another. In this case, there are no brightness fluctuations in the contour except in the transition area into the window boom(s).

Preferably, the verification light has a higher light intensity, preferably at least an integer factor higher, than the ambient light incident on the rest of the outside during the capture of the at least one image.

Preferably, the verification light is only irradiated into the window area or into the window area and at the same time into as small an area as possible around the window area. A pocket lamp or flashlight is preferably placed on one outside so that the verification light irradiates as little as possible into the window area or into areas around the window area in which no window boom is expected or which is not to be evaluated for the presence of a window boom. In order to verify the entire area surrounding the window area, the verification can be carried out one after the other for different areas adjacent to the window area by changing the verification light irradiation. The light source particularly preferably has a light exit surface whose shape is adapted to the shape of the window area. It can either be smaller than or equal to the surface, or slightly larger so that the surrounding contour of the window area is also illuminated.

Still other embodiments provide that the security element has a different degree of transmission between the top side and the window boom area than between the bottom side and the window boom area. To verify this property, the verification is carried out once by capturing the at least one image from the top side and once by capturing the at least one image from the bottom side. The side of the irradiation of the verification light is also changed accordingly. Based on the brightness differences, with otherwise identical irradiation of the verification light, it can be checked whether the determined areas with increased brightness have a brightness difference. If this is the case, the security element is verified as genuine if such a brightness difference is expected, otherwise as false. The difference in brightness of the two compared areas with increased brightness can also be evaluated and compared with specifications.

With the latter type of evaluation and verification, it can also be checked whether the window arm can be detected from both sides or only from one side. This feature can also be used for verification, depending on how the real security element is designed.

It will be understood by the person skilled in the art that the window boom area is not covered transparently at least on the top or bottom side in such a way that a minimum level of transmission for verification light exists, so that an area of increased brightness can be detected during verification by irradiating the window area with verification light.

Fig. 1

eine schematische Draufsicht auf ein Sicherheitselement;

Fig. 2

eine schematische Schnittansicht durch ein Sicherheitselement nach Fig. 1;

Fig. 3

eine schematische Draufsicht auf die Unterseite des Sicherheitselements nach Fig. 1 und Fig. 2;

Fig. 4

eine schematische Schnittansicht durch eine weitere Ausführungsform eines Sicherheitselements;

Fig. 5

eine weitere schematische Schnittansicht noch eines anderen Sicherheitselements;

Fig. 6

eine schematische Explosionszeichnung eines Sicherheitselements;

Fig. 7

eine weitere Explosionszeichnung eines anderen Sicherheitselements;

Fig. 8

eine schematische Draufsicht auf ein sich ergebendes Sicherheitsdokument mit einem Fensterbereich; und

Fig. 9

ein Ablaufdiagramm eines Verifikationsverfahrens zum Verifizieren eines Sicherheitselements mit einem verborgenen Fensterausleger.

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

Fig.1

a schematic plan view of a security element;

Fig.2

a schematic sectional view through a security element according to Fig.1 ;

Fig.3

a schematic plan view of the underside of the security element according to Fig. 1 and Fig. 2 ;

Fig.4

a schematic sectional view through a further embodiment of a security element;

Fig.5

another schematic sectional view of yet another security element;

Fig.6

a schematic exploded drawing of a safety element;

Fig.7

another exploded view of another safety element;

Fig.8

a schematic plan view of a resulting security document with a window area; and

Fig.9

a flowchart of a verification procedure for verifying a security element with a hidden window boom.

In Fig.1 A top view of a security element 1 is shown schematically. The security element 1 is designed as a security document 10. The security element 1 has a non-transparent area 26 that completely encloses and delimits a window area 25. In the non-transparent area 26, the security element 1 is "opaque". In the window area 25, however, it is transparent from a top side 21 to a bottom side 22 that faces the drawing plane, so that it is possible to see through the window area 25 to the information underneath.

In the interior of the security element 1, which has a security element body 20, a window boom is formed which consists of transparent material which merges into the transparent material 51 of the window region 25. The window boom 60, which is located in the boom region 27 on the inside, is not transparently covered by the top side 21 or the bottom side 22. Therefore, the window boom 60 is only shown in dashed lines in this view, since it cannot be seen from either the top side 21 or the bottom side 22 when viewed from above due to the non-transparent cover. However, if the security element 1 is arranged in front of a light source and viewed from the side facing away from the light source, the transmission in the boom region 27 is generally greater than in the rest of the non-transparent region 26. This is increased even further when light enters the window region 25 and partially passes through the transparent material 51 on the inside into the window boom 60.

In all figures, the same technical features are provided with the same reference numerals. The specific deviations from previously described embodiments and figures are described in each case. In Fig.2 is a schematic sectional view through the security element 1 according to Fig.1 shown. The transparent material 51 in the window area 25, which merges into the window boom 60, is clearly visible. This is covered by an upper cover layer 70 to the top side 21 and by the lower cover layer 80 to the bottom side 22. The boom area is therefore not immediately visible when looking at the security element 1. The recesses 73 in the upper cover layer 70 and 83 in the lower cover layer 80 are identical to a window area 42 of the recess 40, which is however larger and additionally includes the boom section 41 in the core layer 30, which is non-transparent. The core layer 30, the upper cover layer 100 and the lower cover layer 110 are therefore all three non-transparent. The window 50 in the window area 25 and the boom 60 in the boom area 26, on the other hand, are made of transparent material. The transparent material in the area of the boom 60 does not have to be identical to the transparent material of the window area 25. However, it is necessary that this material merges into one another without a gap. This allows light to pass from the window 50 into the window boom 60. As a rule, however, it will be the same material, in particular a transparent plastic material, particularly preferably polycarbonate. The core layer 30 and the upper cover layer 70 and the lower cover layer 80 are also preferably made of a plastic material, particularly preferably of the same material as the window 50 and the window boom 60. Polycarbonate is particularly preferred here. However, any other plastics and also fiber-reinforced plastics can be used. Both the core layer and the upper cover layer 70 or the lower cover layer 80 can be multi-layered, ie they can themselves be composite products made of several layers or plies. These can also contain a variety of different security features and/or security elements.

In Fig.3 is the schematic plan view of the underside of the security element 1 according to Fig. 1 and Fig. 2 shown. Here, too, the non-transparent area 26 can be seen, which covers the boom area and encloses and delimits the window area 25. The underside 22 of the security element 1 is also non-transparent in the boom area 27.

In Fig.4 a sectional view of a further security element 1 is shown schematically. This comprises a core layer 30 with a recess 40 which is filled with transparent material 51. The core layer is non-transparent, preferably opaque. The transparent material 51 is covered in the boom section 41 of the recess 40 on the top side 21 by an upper coating 100, for example an upper cover print 101, and on the bottom side 22 by a lower coating 110, for example a lower cover print 111, each in a non-transparent manner. When the security element 1 is viewed from the top side 21, the window boom 60 cannot be seen because it is not transparently hidden by the non-transparent upper coating 100 and when viewed from the bottom side 22 by the lower coating 110. However, when viewed in transmitted light, depending on the choice of coating, there is generally a higher transmission in the area of the cantilever section 27 than in the remaining non-transparent area 28 of the non-transparent area 26 of the security element 1. In addition, light which penetrates into the window area 25 can also reach the window cantilever 60 and thus increase the recognizability of the window cantilever 60 or the cantilever area 27.

In Fig.5 A further embodiment of a security element is shown schematically. This differs from the embodiment according to Fig.4 in that the upper coating 100 for covering and the lower coating 110 for covering are each applied to a transparent upper protective layer 150 and a lower Protective layer 160 is applied. The printing for forming one of the coatings 100, 110 on the upper or lower protective layer 150, 160 can be applied either on the side facing the core layer 30, as shown for the lower protective layer 160, or on the side facing away from the core layer 30, as shown for the upper protective layer 150. The security elements 1 shown in the figures are preferably security document blanks which are combined with further layers to form a security document body. However, they can also be finished security documents.

In Fig.6 a schematic exploded drawing of a security element designed as a security document is shown. A core layer 30 has a recess 40 with a window area 42 and a cantilever section 41. The cantilever area 40 is filled with transparent material in the form of a cantilever insert 61, wherein the cantilever insert consists of transparent material and is slightly larger than the cantilever section of the recess 40. Thus, part of the cantilever insert 61 protrudes into the window area of the recess or the future window area. Towards an upper side, the core layer 30 and the window cantilever insert 61 are covered with a data information layer 90 which is not transparent over its entire surface. These are connected to one another at certain points. The recess 40 is then expanded so that the window area takes on its final shape. At the same time, an information layer recess 94 is created in the information layer. Their edges are aligned with the window area 42 of the recess 40 in the core layer 30. In this process, part of the window boom insert 61 is also severed in order to ensure a clean connection between the transparent material of the window boom 60 and the material that fills the window area 42 of the recess 40 and the window recess 94 in the information layer 90. Here, a transparent window plug 53 is simultaneously inserted into the information layer 90 and the core layer 30 or their window recesses 94, 42. In addition, an upper intermediate layer 180 and a lower intermediate layer 190 are joined to the core layer 30 and the information layer 90, with a non-transparent print 192 being applied to the lower intermediate layer 190, which precisely recesses the window area 25. An upper protective layer 150 is provided on an upper side 21 and a lower protective layer 160 is provided on the lower side 22. All of these layers are heated in a final lamination step and combined to form a security element body.

In an alternative embodiment, similar to the information side 90, a material layer that is not transparent in volume could also be provided below the core layer 30, into which a window recess is introduced at the same time as the extension of the recess 40 of the core layer and the introduction of the window recess 94 of the information layer, after this further layer has also been connected at certain points to the others before the formation of the recess.

In Fig.7 another exploded view of another embodiment of a security document is shown schematically. In this embodiment, the information layer 90 is also the core layer 30 into which the recess 40 is made. This comprises the window region 42 and the display section 41. The recess is filled with a one-piece transparent window display insert 61. A transparent upper intermediate layer 180, which is not printed transparently at least in the display region 27, and an upper transparent protective layer 150 are arranged on the top side. Under the information layer 90, a printed further lower intermediate layer 190, which is provided with a print 192 so that the intermediate layer 190 is not printed translucently at least in the display region 27 and is not printed in the window region 25, and a lower protective layer 160 are arranged. All layers are connected together to form the security element body, which is then a security document body.

In another embodiment, the upper intermediate layer and the further lower intermediate layer can be omitted and an overprint of the cantilever area on the protective layer of the upper protective layer or the transparent insert can be carried out directly or towards the underside on the intermediate layer, the cantilever or the lower protective layer.

In Fig.8 a schematic plan view of a resulting security document 10 with a window area 25 is shown schematically together with an enlarged section of the window 50 in which an extension 62 of the window extension 60 extending into the non-transparent area of the security element can be seen.

Even if the recesses in the various embodiments shown have side or boundary surfaces that are oriented perpendicular to the surfaces of the individual different layers, this is primarily due to a simplified representation. Although recesses with vertically oriented side surfaces are possible embodiments, recesses that are designed with slanted, in particular tapered, side surfaces are preferred. This allows the preferably one-piece pieces of material intended to be inserted to fill the recess to be held optimally during production. These have correspondingly adapted slanted or also tapered side surfaces.

in Fig.9 A flow chart of a verification procedure is shown as an example. Optional features are shown in dashed lines. Optionally, a reference image of a sub-page of a security element, for example a security document as in Fig.8 , captured. Alternatively or additionally, the reference image or another reference image could also be captured from the top. In this case, no verification light is emitted. However, the security element can be evenly illuminated with ambient light.

Verification light is then irradiated into the window area 210, the intensity of which is higher than the intensity of the ambient light, if any. The irradiation occurs, for example, from the top. Alternatively, it could also occur from the bottom of the security element.

At least one image of the security element is then captured 220, which includes at least one area next to the window area, preferably additionally the window area. If a reference image was captured, the image is captured from the side from which the reference image was captured. This can be the side from which the light irradiation occurred or the opposite side.

The at least one image is evaluated for brightness differences in an area adjacent to the window area and an area or several areas with increased brightness are searched for that border the window area 230. If a reference image was acquired, a difference image is formed during evaluation and the brightness differences in the difference image are examined 240.

It is checked whether one or more areas with increased brightness have been found 250 that merge into the window area.

Based on the result of the test, the security element is classified 260. For example, the security element is classified as genuine if an area of increased brightness is found which merges into the window area, and as non-genuine otherwise.

A verification decision is issued based on the classification 270. This can be used, for example, to control an access device.

Optionally, the shape of the area with increased brightness can be determined 280 and compared with a predetermined shape or several predetermined shapes 290. The result of this comparison can be taken into account in the classification 260. If, for example, there is no match with the predetermined shape or one of the several predetermined shapes, the security element is classified as not genuine.

An additional verification step can provide that the irradiation of the verification light during the capture of the at least one image or during the capture of a further image 300 takes place in such a way that a narrow strip of the area around the window region along at least one contour section of the window region is irradiated with the verification light. The window contour is now examined 310 for brightness fluctuations outside a transition region from regions of increased brightness to the window region. If such fluctuations are found, this is an indication that the recesses of the core layer and covers, e.g. the cover layers, are not aligned. A document is then also classified as not authentic in step 260 if such brightness fluctuations are found.

Additional tests can be included in the verification. For example, the same test can be carried out on both sides of the security element.

The verification can be carried out from one side, ie by shining the verification light and capturing at least one image from the same side of the security element. This examination is particularly advantageous for detecting apparent forgeries that can simulate a similar effect in transmitted light. Only the examination of the contour of the window area is improved if this is designed in such a way that the light is emitted from the side opposite to the side from which the at least one image is captured.

Examining whether the contours of the various recesses that define the window section are correctly aligned with one another, possibly in different directions in certain sections, can be an independent or supplementary verification procedure. This verification can also be carried out using other optical means, such as a magnifying glass or a microscope.

List of reference symbols

1

Security element

10

Security document

20

Safety element body

21

Top

22

bottom

25

Window area

26

non-transparent area

27

Boom range

30

Core layer

40

Recess

41

Boom section

42

Window area of the recess

50

Window

51

transparent material

53

Window plugs

60

Window boom

61

Window cantilever insert

62

Attachment of the window boom

70

upper covering layer

73

Recess in the upper covering layer

80

lower covering layer

83

Recess in the lower cover layer

90

Information layer

94

Window recess

100

upper coating

101

upper cover pressure

110

bottom coating

111

lower cover pressure

150

upper protective layer

160

lower protective layer

180

upper intermediate layer

190

lower intermediate layer

192

non-transparent print

200

Capturing a reference image

210

Shining verification light into the window area

220

Capture at least one image

230

Evaluating at least one image

240

Creating a difference map and evaluating this difference map

250

Check if an area of increased brightness exists

260

Classifying the security element

270

Outputting a verification result

280

Determining a shape of the area of increased brightness

290

Compare the shape with given shapes

300

Capturing another image

310

Examine the imaged window contour for brightness variations

Claims (4)

1. A method for verifying a security element comprising a security element body (20) having a window portion (25), in which the material of the security element body (20) is transparent between a top surface (21) and a bottom surface (22), wherein the window portion (25) is surrounded and delimited peripherally by a non-transparent region (26) of the security element body (20), wherein the window portion (25) merges into a transparent window extension (60) which extends into the non-transparent region, wherein, however, the window extension (60) is covered completely non-transparently towards the top surface (21) and towards the bottom surface (22) of the security element body (20), or a security element produced according to a method of manufacturing a security element, wherein the security element produced by the manufacturing method comprises a security element body (20) having a window portion (25) extending from a top surface (21) to a bottom surface (22), which window portion is formed of transparent material which merges into a window extension (60), the transparent material of which is covered completely non-transparently towards the top surface (21) and the bottom surface (22), wherein the manufacturing method comprises the following steps:

   providing a core layer (30) which is non-transparent at least in one areal portion, making a recess (40) in the core layer (30) inside the non-transparent areal portion so that the recess (40) is surrounded peripherally by a non-transparent part of the areal portion,

   inserting transparent material into the recess (40);

   non-transparently covering an extension section of the recess (40) towards the top surface (21) and towards the bottom surface (22) and introducing heat to form the security element body (20),

   wherein in the verification method, verification light is radiated into the window portion of the security element, at least one image of the top surface or the bottom surface is captured which comprises at least one area adjacent to the window portion, and the image is analysed for differences in brightness in the area adjacent to the window portion, wherein the security element is classified as authentic if in the area adjacent to the window portion an area of increased brightness is detected which is adjacent to the window portion and the verification decision is issued based on the classification,

   wherein in the verification method a reference image of the top surface is captured accordingly, if at the at least one image is captured from the top surface, or of the bottom surface, if the at least one image is captured from the bottom surface, wherein no verification light is radiated into the window portion during the capture of the reference image, and during the evaluation of the at least one image firstly a difference is formed with the reference image and differences in brightness are determined in the difference image, wherein the security element is only classified as genuine if an area of increased brightness, which is adjacent to the window area, is detected in the difference image.
2. The method according to claim 1, characterised in that a shape of the area of increased brightness is determined and compared with a predetermined shape or a plurality of predetermined shapes and is only classified as genuine if the determined shape matches the one predetermined shape or one of the plurality of predetermined shapes.
3. The method according to any one of claims 1 or 2, characterised in that a radiation area of the verification light covers a contour section of the window portion completely or in some sections during the capture of the at least one image, or a further image of the security element is captured while a radiation area of the verification light covers the contour section of the window portion completely or in some sections, and in the at least one image or the one further image the contour section of a contour of the window portion is examined for brightness fluctuations outside a transition area of the area with increased brightness and is only classified as genuine if no brightness fluctuations are detected in the contour section outside the transition area.
4. The method according to any one of claims 1 to 3, characterised in that the at least one image is detected from the top surface when the verification light is radiated via the top surface, or alternatively the at least one image is detected from the bottom surface when the verification light is radiated via the lower surface.

Images