EP0779863A1

EP0779863A1 - Visually identifiable optical element

Info

Publication number: EP0779863A1
Application number: EP95929745A
Authority: EP
Inventors: Werner Reinhart; Jürgen Herrmann; Thomas Stange
Original assignee: Deutsche Bundesbank; Leonhard Kurz GmbH and Co KG
Current assignee: Leonhard Kurz Stiftung and Co KG; Deutsche Bundesbank
Priority date: 1994-09-09
Filing date: 1995-08-31
Publication date: 1997-06-25
Anticipated expiration: 2015-08-31
Also published as: US6623042B1; CA2199503A1; WO1996007547A1; DE59502776D1; AU3340495A; BR9508904A; CA2199503C; TW400284B; ES2119463T3; CN1157595A; JPH10505022A; HK1003429A1; AU685318B2; RU2136508C1; DE4432062C1; ATE168075T1; EP0779863B1; CN1054574C

Abstract

So that a visually identifiable optical element, in particular a security element for value-bearing documents, for example banknotes, credit cards, passes or cheque documents, or other articles to be safeguarded, comprising a carrier with a diffusely reflecting visible surface and a metallization which is applied in a region-wise manner to the visible surface of the carrier and which has a surface that appears metallically shiny at a glancing angle is improved in such a way that an article provided with the element is even more effectively protected from forgery than is possible with known optical elements, it is proposed that the optical element is so designed that the visible surface of the carrier has two carrier regions with different levels of and in particular diffuse reflectivity for light, wherein a respective sub-region or a plurality of sub-regions of each of the two carrier regions is or are metallized, and that the reflectivity of the metallization in viewing directions outside a glancing angle range is less than the reflectivity of the carrier region with the higher level of reflectivity or substantially corresponds to same and is greater than the reflectivity of the carrier region with the lower level of reflectivity or substantially corresponds to same.

Description

Visually identifiable optical element

The invention relates to a visually identifiable, optical element, in particular a security element for documents of value, e.g. Banknotes, credit cards, ID cards or check documents, or other objects to be secured, comprising a carrier with a diffusely reflecting visible surface in particular and a metallization applied in some areas to the visible surface of the carrier with a surface that appears to have a metallic sheen under a glancing angle.

In known optical elements, the metallization appears before the one formed by the carrier

Background for the metallization either light or dark. Such an optical element is described for example in WO 93/01057.

The use of a support with a metallization as a visually identifiable optical element for security or decorative purposes is based on the physically explicable phenomenon that light from a certain direction, hitting a smooth metal surface, is perceived by a viewer in the form of reflected light in a certain viewing direction can. However, if the light does not come in from a single specific direction, it is, for example, diffuse incident daylight or around light from a diffuse light source, depending on the orientation of the metallized area to the angle of incidence of the light, there is a viewing angle area, hereinafter referred to as the glancing angle area, from which a viewer perceives the metallization as high-gloss and bright metallic, since a large part of the light reaching the metallization within the incidence angle range is reflected in this gloss angle range. The reflectivity dependent on the viewing angle is thus particularly large in this gloss angle range determined by the angle of incidence of the light, ie a large part of the radiation power reaching the unit area of the metallization is reflected in this gloss angle range. On the other hand, for viewing directions outside the range of the gloss angle, the metallization does not appear shiny to an observer, but rather gives a metallic gray and matt color impression. Depending on the light reflectivity of the wearer, this matt color impression appears either light or dark against the background.

Metallization is understood below to mean any layer, in particular a very thin layer, with a shiny metallic surface.

Using visually identifiable, optical elements or security elements, an attempt is made to make the inexperienced layperson aware of the authenticity information of the secured object and, at the same time, to make a falsification, for example in the form of a reproduction, taking into account known counterfeiting processes, in particular optical reproduction processes, impossible or at least sufficient complicate. Such optical elements are also used for decorative purposes.

The invention is therefore based on the object of creating an optical element of the type described at the outset, which can be produced simply and economically and with which an object to be secured can be protected even more effectively against counterfeiting than is possible with known security elements.

This object is achieved according to the invention in the case of an optical element as described at the outset in that the visible surface of the support has two support areas of different levels, in particular diffuse reflectivity for light, a partial area or more partial areas of each of the support areas being or being metallized, and that the reflectivity of the metallization in viewing directions outside a gloss angle range is less than the reflectivity of the carrier region with the higher reflectivity or essentially corresponds to it and is greater than the reflectivity of the carrier region with the lower reflectivity or this essentially corresponds.

Because the carrier is divided into at least one region of higher light reflectivity and one region of lower light reflectivity and the reflectivities of these carrier regions and the metallization satisfy the relationships described above, the information which can be conveyed to the viewer by means of the optical element is visually perceptible depending on the viewing angle; in a certain viewing direction, a metallized sub-area appears in front of the outside of the gloss angle area background formed by the carrier area with higher reflectivity is dark, while another metallized sub-area appears bright in front of the background formed by the carrier area with lower reflectivity, provided that the reflectivity of the metallization in the first case is smaller and in the second case larger than the reflectivity of the respective carrier area under consideration .- If the reflectivity of the metallization in a viewing direction outside the gloss angle range essentially corresponds to the reflectivity of the dark support area, i.e. if no difference in reflectivity can be seen with the naked eye, the metallized sub-area of this support area is when viewed outside the gloss angle range before Background not or hardly noticeable. If, on the other hand, the security element is viewed in the gloss angle range of the metallization, which is determined by the angle of incidence of the light, the metallization appears to be metallic bright with respect to the two support regions. The same applies correspondingly if the reflectivity of the metallization viewed in a viewing direction outside the gloss angle range essentially reflects the diffuse reflectivity of the bright support range The production of the optical element according to the invention is only more difficult than the production of known elements in a manner that is not worth mentioning. For example, one half of the carrier can be designed to appear white, in particular with a visible surface made of diffusely reflecting white paper, while the other half of the carrier can be colored black with a reflectivity which can therefore be neglected. The section of the metallization which is applied to the black area of the carrier, that is to say to the area of lower reflectivity, appears against this dark background in a matt, metallic light gray shade. The section of the metallization, which is applied to the white support area, that is to say the support area of higher reflectivity, appears against this light background in a matt, metallic dark gray color tone and stands out from the light background as dark. If the optical element is now oriented with respect to the direction of the light impinging on it in such a way that a viewer has the element or the metallized area in front of the eye in the aforementioned angle range, then the portion of the metallization that partially covers the white area of the support appears , no longer dark, but brilliantly shiny and brilliantly bright. The section of the metallization applied to the black area of the support also appears shiny metallic bright when it is in a viewing direction within the

Gloss angle range is considered. Here, too, the visually perceptible information changes when the orientation of the element or the viewing direction is changed.

Although the optical element according to the invention can be produced in a particularly simple and economical manner by using a carrier with a white and a black area, it can also prove to be advantageous, in particular aesthetic

Considerations are more fair if the at least two areas on the visible surface of the wearer are designed differently. Within the limits of the teaching conveyed by the invention there are broad ones Possible variations. For example, the area of higher light reflectivity can have a light color and the area of lower reflectivity can have a dark color. It is only necessary to ensure that the relationships given above of the reflectivities of the respective surrounding areas of the carrier or of the metallization are observed. In particular, if the visible surface of the carrier area of lower reflectivity is to appear in a dark gray color tone, it is possible to design the optical element so that the reflectivity of the metallization essentially corresponds to the diffuse reflectivity of the dark gray background, so that for viewing directions that are outside the gloss angle range, the metallization does not stand out from the dark gray background, but only becomes visible to a viewer when viewed within the gloss angle range.

It goes without saying that the region-by-region metallization of the respective carrier regions can have any shape, that is to say can also be applied to the carrier in the form of signs or symbols.

In the simplest case, the region-wise metallization of the carrier regions can be realized by a single coherent section of a metal layer of any geometric shape, which is applied to the carrier region to cover the boundary between light and dark regions. However, it is also possible for a plurality of partial regions, in particular a large number of partial regions, of the two carrier regions to be metallized; the metallization can be applied to the carrier in a way that forms a visually perceptible pattern. The pattern can be in shape cover the carrier of regularly arranged partial areas of any geometric shape, the background always remaining visible between the metallized partial areas. It may prove particularly advantageous that the metallization is applied to the carrier in the form of a visually perceptible halftone image-producing dot or line grid.

In order to further increase the number of information that can be transmitted by means of the optical element and thus

To transmit information about a secured object more effectively and at the same time make it more difficult to forge the optical element or the secured object, it proves to be advantageous if the carrier has several areas of the same reflectivity. This can be done very easily, e.g. a square girder or girder section is divided by an imaginary vertical and a horizontal into four square sections, of which the sections lying on a diagonal are identical and the

Form carrier area of higher or lower reflectivity. It goes without saying that other conceivable subdivisions of the carrier into areas of higher and lower light reflectivity are covered by the teaching according to the invention.

Optical elements according to the invention can also comprise more than two carrier regions or groups of carrier regions with different reflectivity. The relationships for the reflectivities of the individual areas and the associated metallizations are then to be applied accordingly. In a particularly preferred embodiment of the optical element, at least one of the carrier regions is designed with reflectivity which varies in dependence on the viewing angle and is of different heights. Ie when changing the viewing direction, for example by swiveling the support around an axis lying in its plane, not only does a change in the reflectivity of the metallization occur, for example due to a transition to the gloss angle range or by leaving the gloss angle range, but it also changes Reflectivity of the support area surrounding the metallization. For this purpose, the visible area of the carrier area can be coated with an optically effective thin film coating, which for example is white for certain viewing directions and for others

Viewing directions, for example, gives a color impression that appears green. However, it is also conceivable to design the visible surface of the support area in such a way that the coating appears transparent for viewing directions outside of the glancing angle area and thus the reflectivity of the visible area of the wearer is determined by the support area located underneath, while in a different viewing angle area, in particular in the gloss angle range, the coating is colored, e.g. violet background for the metallization forms.

In a further embodiment of the invention, it is proposed to provide a support area with reflectivity that varies depending on the illumination or viewing angle, instead of two spatially separate support areas of differently high reflectivity, and to design them so that viewing directions outside the gloss angle area of the metallization exist in which the reflectivity of the metallization is less than the reflectivity of the carrier region or essentially corresponds to it, and that there are other viewing directions in which the reflectivity of the metallization is greater than the reflectivity of the carrier region or this essentially corresponds.

The effect initially brought about by the formation of two carrier regions of differently high reflectivity, that a metallization appears once light and once dark, depending on the background against which it is viewed, can be brought about in an optical element designed as described above by changing the viewing angle. It is thus possible to design the support in such a way that the metallization appears dark in one viewing direction outside the glancing angle range compared to the background formed by the visible surface of the support and in another viewing direction the metallization appears bright in front of the support background, in particular the support in another Color appears as in the first direction. It is also conceivable to design the optical element in such a way that a change in the reflectivity or the color of the support can be observed when entering the gloss angle range of the metallization or when leaving the gloss angle range.

Such effects can be achieved in a wide variety of ways by means of a wide variety of optically effective thin film coatings on the visible surface of the wearer. An optical element can therefore be designed in such a way that not only a transition from a state with a metallization that appears dark to the background into a state with compared to the background of bright metallization can be achieved, but that at the same time a change in the color impression emanating from the carrier, for example from white to violet, is brought about.

Coatings of the carrier area are also conceivable, which appear transparent in viewing directions outside the gloss angle range of the metallization and thus do not or hardly influence the reflectivity of the carrier and the light / dark or dark / light contrast of the metallization in front of the carrier, but which do so within viewing directions form a colored, optically perceptible background for the metallization.

The optical effectiveness of the carrier coating can be based on physical effects known per se, such as extinction or superimposition of light waves, or on the chemical composition of the substances used for this.

In a further preferred embodiment of the optical element, structures that cause diffraction and / or interference are integrated into the metallization. By including such structures, which can also be referred to as diffraction structures, in the shiny metallic surface areas, additional spectral color effects can be observed in diffraction angles determined by the structure and the frequencies of the incident light, in particular also outside the actual gloss angle range. An optical element designed in this way conveys additional information and is therefore even more reliable with regard to its counterfeitability. In a further development of the invention, it is proposed to design the optical element in such a way that the metallization comprises a metallic, glossy, relief-like structure consisting of elevations which extend essentially parallel to one another and that the valleys between the elevations have a surface structure which gives a metallic matt image impression. When viewing an optical element designed in this way in a direction substantially perpendicular to the linearly extended elevations, the metallization can be perceived as brightly metallic within its gloss angle range. In contrast, in a viewing direction essentially parallel to the linearly extending elevations, the surface structure provided in the valleys between the elevations has the effect of a matt-appearing image impression. When considering the metallization within the range of the gloss angle, it is thus possible to change from a metallic impression of the image to a metallic impression of the image or vice versa by rotating the optical element about an axis running perpendicular to the plane of the support.

The invention also relates to a document holder, in particular in the form of a section of a

Flat material web e.g. made of paper or plastic, which was improved with regard to its security against forgery by having an inventive security element. In preferred value document carriers, the carrier of the security element is formed by the value document carrier itself.

Further features, advantages and details of the invention will become apparent from the accompanying drawing and from the the following description of advantageous embodiments of the optical element according to the invention. Show it:

Figure 1: A schematic diagram of a known optical

Element;

Figure 2 is a schematic representation of an optical element according to the invention;

Figure 3: a schematic representation of another

Embodiment of the optical element according to the invention;

Figure 4 is a schematic representation of a third

Embodiment of the optical element according to the invention with a metallization in pattern form;

Figure 5: a schematic representation of a fourth

Embodiment of the optical element according to the invention with a metallization in the form of points and line screens;

Figure 6: a schematic representation of a fifth

Embodiment of the optical element according to the invention with several carrier areas of the same reflectivity;

Figure 7: a schematic representation of a sixth

Embodiment of the optical element according to the invention with a carrier region of varying reflectivity and with a metallization having structures, and Figure 8 is a schematic representation of a document holder with an optical security element according to the invention.

FIG. 1 shows an optical element which is known in principle and is designated overall by reference number 1 and which is used as a security element. This optical element 1 comprises a flat carrier 2 with a

Subarea 4, on which a metallization 6, not shown in detail, is applied, which can be formed from a homogeneous metal layer or by metallic halftone dots that produce a halftone image. The carrier 2 has e.g. an optically bright, diffusely reflective

Visible surface 8, which faces a viewer V and forms the background for the metallization 6, but which in turn can also include information, for example in the form of watermarks, thin hatching, etc. If light within an angle of incidence range gamma from a diffuse light source in particular or in In the form of diffuse daylight falling through a window onto the element 1 or onto the metallization 6, a large part of the incident light can be perceived in the form of reflected light within a glancing angle range alpha. The metallization then appears high-gloss and stands out from the optically bright but diffusely reflecting visible surface 8 of the carrier 2 with a metallic sheen and a bright appearance. In viewing directions outside the gloss angle range alpha, the metallization 6, on the other hand, conveys a matt, metallic dark gray color tone that stands out against the optically bright background of the support 2. Figure 2 shows a first embodiment of the optical element according to the invention. This comprises a carrier 10, the visible surface 12 in an area 14 with high diffuse light reflectivity (sigmaT,>) and in an area 16 with low diffuse light reflectivity

(sigmaT, <) is divided. The area 14 conveys a white color impression, ie reflects the frequencies of the visible spectrum equally, while the area 16 absorbs the visible light and therefore appears black. The areas 14, 16 can in turn also include information. A partial region of the carrier 10 is indicated by the reference symbol 18, to which a metallization 20 is applied in a manner not shown in any more detail. The metallization 20 or the subarea 18 is half in the light area 14 and the other half in the dark area 16. The metallization 20 has a reflectivity sigmaM that is smaller in a viewing direction outside of its gloss angle range explained in connection with FIG. 1 is than the reflectivity sigmaT,> the area 14 with high reflectivity but is higher than the reflectivity sigmaT, <the area 16 with low reflectivity. If the partial area 18 is viewed from a direction which, taking into account the incident light, lies outside the glancing angle area, the metallization 20 appears before the bright one

Background of area 14 is dark, while the portion of metallization 20 that is applied to dark carrier area 16 appears bright. Different optical information can thus be conveyed to an observer by means of one and the same metallization. In viewing directions within the gloss angle range, the metallization appears bright in relation to both carrier regions 14, 16, since the reflectivity of a smooth metallic surface is within it Gloss angle range is greater than the reflectivity of the diffusely reflective support.

FIG. 3 shows another embodiment of the optical element according to the invention, which differs from the embodiment shown in FIG. 2 in that instead of a coherent metallization 20 covering both carrier regions with different reflectivity in regions, two metallized partial regions 24, 26 are provided on a carrier 28, wherein the partial area 24 lies within a bright support area 30 and the partial area 26 lies within a dark support area 32. With this optical element, two different, visually perceivable information items starting from spatially separated areas of the carrier can be transmitted using the same metallization. The partial areas 24, 26 can also have the shape of different symbols.

FIG. 4 shows a particularly preferred embodiment of the optical element according to the invention. In the case shown, the metallization is applied to this in the form of a regular pattern covering the visible surface 34 of a carrier 36. The pattern is characterized by metallized square sections 38, which are in the manner of a

Touch checkerboard pattern at the corners, trained. The metallized sub-areas 38 appear dark in viewing directions outside of the glancing angle area against the light background of a carrier area 40 with high reflectivity. A carrier area 42 with low light reflectivity has a visible surface in such a gray tone in the case shown that the metallized partial areas 38 covering this carrier area 42 are in a viewing direction outside the Do not raise the gloss angle range alpha from the gray background and therefore cannot be perceived by an observer (however, this is not shown here). In this case, the reflectivity of the metallization sigmaM essentially corresponds to the reflectivity sigmaT, <des

Carrier area 42. Carrier area 42 therefore appears gray over its entire extent. The pattern shown in FIG. 4 can only be perceived on the support area 42 if the support area 42 is viewed in a direction within the gloss angle range. Such a security element can also be safely handled and understood by an inexperienced layperson.

As can be seen from FIG. 5, the metallization can also be formed by various forms of dot or line grids which produce a halftone image 52. The raster points 50 are in the illustrated case on a carrier area 54 with a high

Light reflectivity applied. Metallization in the form of a line grid of strips 58 running essentially parallel to one another is applied to a carrier region 56 with low light reflectivity. By varying the width of the lines or strips 58 over their longitudinal extent, a visually perceptible halftone image is generated.

FIG. 6 shows a further preferred embodiment of the optical element according to the invention, in which a carrier 60 is divided into several areas 62 or 64 of the same reflectivity. The areas with the reference symbol 62 have a lower reflectivity and therefore appear dark, while the areas 64 have a high reflectivity and consequently appear bright. A metallization 66 is located in the regions 62 and 64 arranged at the top in FIG. 6 and 68 are provided in the form of metallic grid dots that combine to form numbers. In the carrier regions 62 and 64 arranged at the bottom in FIG. 6, metallization is applied to the carrier 60 in the form of a letter. When viewing outside the

The letter "D" appears bright against the dark background of the carrier area 62, while the letter "M" appears dark against the light background of the carrier area 64.

The optical elements shown in FIGS. 2 to 6 or the visible surfaces of the carrier regions 14, 16, 30, 42, 40 42 can be designed by means of an optically effective thin film coating in such a way that their reflectivity changes as a function of the illumination or viewing angle. It is e.g. it is possible that the carrier area 64 of the carrier 60 shown in FIG. 6 appears white in a certain viewing direction, but forms a colored background for the rastered metallization 68 in another viewing direction.

If, prior to the application of the grid-shaped metallization to the section of the carrier area 64 to be metallized, which has the shape of the number “10”, this section is optically darkened, in particular blackened, it is possible to provide the screening in such a way that the reflectivity of the grid-shaped area in the gloss angle area Metallization 68 essentially corresponds to the reflectivity of the carrier area 64, so that the symbol represented by the rasterized metallization is barely or not perceptible in the glancing angle area.

It is also conceivable for the metallized subregions of the optical elements shown in FIGS. 2 to 6 to integrate diffraction structures with optical diffraction effects. It is then possible to observe spectral color effects defined in the diffraction angles, in particular outside the actual specular angle range, which, as additional authenticity information, make it more difficult to forge the object to be secured.

7 shows a further advantageous embodiment of the optical element according to the invention, in which one forms the entire visible surface 70 of a carrier 72

Carrier area 74 is formed by a suitable optically effective thin film coating, in particular an effect pigment, in such a way that it has a varying reflectivity depending on the illumination or viewing angle; so the carrier area 74 conveys

Viewing in a first viewing direction a first color impression and viewing in a second viewing direction a different color impression. A partial area 76 of the support area 74 carries a metallization 78 which appears dark in a viewing angle area outside its gloss angle area alpha with respect to the support area 74, in another viewing direction, in particular within its gloss angle range, but bright. The surface of the metallization 78 comprises relief-like, essentially Metallic elevations 80 extending parallel to one another, valleys 82 between the elevations 80 having a surface structure 84 imparting a metallic matt image impression. When viewing the optical element in one direction within the

The gloss angle range alpha and essentially perpendicular to the linearly extended elevations, the metallization 78 appears bright metallic. In a viewing direction essentially parallel to the Elevations 80 make the surface structure 84 provided in the valleys 82 visible and thus optically effective, so that a viewer is given a matt, metallic gray image impression.

FIG. 8 shows a security document carrier 90 with a security element 92. The security document carrier 90 comprises a flat material web made of plastic, such as is used in particular for the production of check cards or the like, and has on its visible surface 94 a region 96 which appears light and a region 98 which appears dark which are covered by a metallization in the form of metallized partial regions 100 arranged in a checkerboard manner. The mode of operation of this value document carrier 90 designed according to the invention corresponds to the mode of operation of the optical elements explained in connection with the preceding figures.

Claims

Claims:

1.Visually identifiable, optical element, in particular a security element for documents of value, e.g. banknotes, credit cards, ID cards or check documents, or other objects to be secured, comprising a carrier with a diffusely reflecting visible surface in particular and a metallization applied in some areas to the visible surface of the carrier surface that appears to have a metallic sheen, characterized in that the visible surface (12, 34) of the support (10, 28, 36) has two support areas (14, 16; 30, 32; 40, 42) of different heights, in particular diffuse reflectivity for light having a partial area (18, 24, 26) or a plurality of partial areas (38)

each of the two carrier regions (14, 16; 30, 32; 40, 42) is or are metallized, and that the reflectivity (σM) of the metallization is less than that in viewing directions outside a specular angle range (et)

Reflectivity of the support area (14, 30, 40, 54, 64) with the higher reflectivity (σ _τ> ) or essentially corresponds to it and is greater than the reflectivity of the support area (16, 32, 42, 56) with the lower reflectivity ( σ _{τ <} ) or this essentially corresponds.

2. Optical element according to claim 1, d a d u r c h g e k e n e z e i c h n e t that the metallization in the form of a visually perceptible halftone image (52) generating dot or line grid (50) is applied to the carrier.

3. Optical element according to claim 1 or 2, so that the metallization is applied to the support to form a visually perceptible pattern, a sign, a symbol or a figure.

4. Optical element according to claim 3, d a d u r c h g e k e n n z e i c h n e t that the metallization in the form of regularly arranged, diamond-shaped sections (38) covers the carrier (36).

5. Optical element according to one or more of the preceding claims, characterized in that the carrier (60) has several areas (62, 64) of the same

Has reflectivity.

Optical element according to one or more of the preceding claims, d a d u r c h g e k e n n e z e i c h n e t that the carrier has more than two areas of differently high reflectivity.

7. Optical element according to one or more of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that metals of different reflectivity are used for the region-by-region metallization of the carrier regions of differently high reflectivity.

8. Optical element according to one or more of the preceding claims, so that at least one of the carrier regions (14, 16; 30, 32; 40, 42) is designed with reflectivity that varies as a function of the viewing angle.

9.Visually identifiable, optical element, in particular a security element for documents of value, e.g. banknotes, credit cards, ID cards or check documents, or other objects to be secured, comprising a carrier with a diffuse reflecting visible surface in particular and a metallization with a region applied to the visible surface of the carrier under a Shine angle surface which appears to be shiny metallic, characterized in that the visible surface (70) of the support (72) has a support area (74) as a function of

Has illumination or viewing angle of varying reflectivity, and that the carrier is designed so that viewing directions exist outside a gloss angle range (α) in which the reflectivity (σ _M ) of the metallization (78) is less than the reflectivity (σ _τ ) of the Carrier area (74) or this essentially corresponds, and that there are other viewing directions in which the reflectivity (σ ^) of the metallization (78) is greater than the reflectivity (σ _τ ) of the carrier area (74) or this corresponds essentially.

10. Optical element according to one or more of the preceding claims, that the support region (74) has an optically effective thin film coating.

11. Optical element according to one or more of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that in the metallization (78) a diffraction and / or interference-causing structures are integrated.

12. Optical element according to one or more of the preceding claims, characterized in that the metallization (78) is a relief-like, in comprises essentially metallic mutually extending elevations (80) and that the valleys (82) between the elevations have a surface structure (84) imparting a metallic matt image impression.

13. Document carrier of value, in particular in the form of a sheet of flat material made of paper or plastic, is an optical security element 92 according to one or more of claims 1 to 11.

14. The document carrier according to claim 12, so that the carrier of the security element 92 is formed by the document carrier 90 itself.