EP2708371B1 - Visually variable security element with additional visual reflection/transmission effect - Google Patents

Description

The invention relates to an optically variable security element which has a combination of thin optically active layers, which has at least one first color impression in plan view and at least one second color impression in view, wherein the optically variable security element has an additional up / translucent effect. The invention further relates to a method for producing such an optically variable security element.

Today, color-shift and see-through effects are usually realized by means of optically variable security elements in which a combination of thin optically active layers with successive metal and dielectric layers is deposited on top of one another on a carrier film. These effects show a relatively unambiguous color change from a defined color to a further defined color when viewing the functional layer carrier provided with color effect, for example through a hole in the carrier substrate on which the functional layer carrier is applied.

Such optically variable security elements are, for example, thin-film elements which consist of a reflector layer, a dielectric and an absorber layer. If the security element is viewed from the absorber side, the viewer perceives a certain color, which changes as the viewing angle changes.

The cause of the color shift is an interference effect between the light rays reflected from the surface of the outer partially transmitting layer (absorber layer) and the light rays passing through the outer partially transmitting and the middle dielectric layer and be reflected back from the inner metal reflector layer to the partially transmissive layer. The light beams are then either transmitted to the outside or reflected again at the partially transparent layer, so that in this case the light beams are repeatedly reflected back and forth between the reflection layer and the partially transparent layer. Thus, the light rays that have passed through the thin film layer have traveled a longer distance than the light rays reflected on the surface of the thin film layer, so that they are out of phase with each other when interfering with them.

When the light beams incident on the thin-film layer strike the thin-film layer at different angles of incidence, the path of the light beams traversed in the thin-film layer is of different lengths. This difference results from the path difference of the beams reflected multiple times within the thin film layer due to the angle of incidence. Therefore, the phase angle of the interfering light beams is different depending on the angle of incidence, so that depending on the angle of incidence different colors or hues of the resulting, perceived by the observer light beam result.

Out WO 2009/149831 A2 a security element of at least one thin-film element in the form of an interference-capable, multilayer structure is known. The interference-capable, multilayer structure consists of at least one reflective layer, at least one partially transmissive layer and at least one dielectric layer arranged between these layers. Here, the security element has a plurality of recesses in the reflective layer in a first region and at least one recess or a plurality of recesses in the partially transparent layer in a second region. In this case, the second region is arranged at least partially within the first region and the total area of the second area located at least partially within the first area is smaller than the total area of the first area. Thus, viewed from the semi-permeable layer, the security element has a different appearance in plan view than in phantom.

Out WO 2009/149833 A2 For example, a security element made of at least one light-transmissive substrate is known, on which there is a substantially opaque, screened layer of raster elements. In this case, at least one thin, continuous, substantially opaque line is arranged within the substantially opaque, screened layer of raster elements, which line has the shape of at least one alphanumeric character, a graphic or a pattern. Such lines have line widths of at least 0.1 mm to 5 mm, preferably from 0.2 mm to 0.7 mm, more preferably about 0.5 mm. Instead of lines, it is also possible to use area-like areas without recess, so that the alphanumeric character, pattern or graphic formed can only be seen in a transparent manner but not in a plan view. This security element thus shows, viewed at least from the side of the substantially opaque, screened layer, a different appearance in supervision than in transparency.

Disadvantage of the prior art is that the shaping of the evaporated layers, e.g. By demetallizing only relatively simple motives, since on the one hand a limitation of line width sets creative limits, on the other hand, the removal of supervisory / transparent surface reduces the effect.

Out DE 10 2009 053925 A1 is an optically variable security element with an array of metallic coated sawtooth structures known to which a metallic coating is applied.

Out WO 01/53113 A1 is an optically variable security element with a combination of thin optically variable layers known, for example US 5,278,590 are known, wherein the optically variable security element is combined with an optical interference pattern. This optical interference pattern here consists of a diffractive structure or a microstructure.

Out DE 10 2008 013167 A1 For example, a security element for protecting valuables is known in which a thin-film element with a color-shift effect and a relief structure present in an embossing lacquer layer are arranged one above the other. The embossing lacquer layer with the relief structure is metallised in partial areas. The relief structure of the partially metallized embossing lacquer layer is flattened with a transparent lacquer layer whose refractive index essentially corresponds to the refractive index of the embossing lacquer layer.

WO 97/47478 A1 discloses the preamble of claim 1.

It is thus an object of the invention to produce a more complex embodiment of a security feature, e.g. by creating a see-through / supervisory color effect with a filigree theme. This motif is preferably not visible in plan view or only visible on one side and can be seen in the see-through a very fine motif, which produces in a different color or brightness by means of a combination of a certain metallic or colored or opaque structure with the transparent / obersichtschicht applied over it becomes.

This object is solved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

According to the invention, the additional open / see-through effect is produced by at least one arrangement of picture elements which is applied to at least one side of the optically variable security element.

These picture elements are particularly preferably designed as raster elements, wherein the individual raster element may be designed point or line-shaped or may take any other shape, such as square, rectangular, triangular or star-shaped. The arrangement of raster elements preferably forms in its entirety at least one alphanumeric character, a graphic or a pattern. A grid according to this invention is a uniform or non-uniform arrangement of grid elements, wherein the grid elements are spaced apart.

Furthermore, the picture elements are preferably designed as at least one continuous or interrupted area or line in the form of at least one alphanumeric character, a graphic or a pattern. For example, an area of substantially opaque and transparent image portions may be a paper-like representation of a person or the value of a banknote that is positive, i. dark against a light background, or negative, i. e. bright against a dark background, is shown. Shadow-like effects can also be displayed here, wherein, for example, the edge of a graphic on one side is made wider than the edge of the opposite side.

Of course, picture elements can also be designed from a mixture of raster elements and continuous or discontinuous surfaces, wherein a part of the alphanumeric character to be imaged, the graphic or pattern consists of raster elements and another part consists of one or more continuous or discontinuous areas.

In accordance with the invention, the security element thus consists of functional layers appearing to appear in different colors in a plan view and transparency, in combination with fine demetallizations or colors or the like.

The invention in this case comprises both a substrate with a security element and a data carrier with a substrate with a security element. In this case, the data carrier is in particular a value document, such as a banknote, a security, a credit or identity card, a passport, a document and the like, a label, a packaging or another element for product assurance.

A particular advantage of the invention is that in review not only a motif, but also a different color of the supervisory color is visible. For this purpose, in particular semitransparent layer systems are used with a structure absorber dielectric absorber. Preferably, an absorber layer can be replaced at least in regions by a reflector layer.

According to a preferred embodiment, the grid elements consist of an ink or of a metallic or metal-like coating. Preferably, a raster print or a corresponding separate Rasterdemetallisierung is thus generated, which is deposited the color / metal support. Various embodiments allow a plethora of combinations that result in a new and improved feature. The printing or vapor deposition material can be paint, or metal and dielectric. Other embodiments may include fluorescent colors, colors of different transparency or within a spectral range more or less active colors or different metals. Combinations of versions are possible by substrate design with two windows within a banknote.

According to a further advantageous embodiment, the grid is produced by means of a so-called washing process, in particular from the WO 99/13157 A1 is known. Here, a washing ink is applied to the at least one side of the optically variable security element, wherein the washing color forms a pattern which is inverted to the pattern. A covering layer is applied to the washing paint and the covering layer is removed again by means of a washing process at the points below which the washing ink is located, so that the at least one arrangement of grid elements is produced.

In further, likewise advantageous embodiments, the structuring can take place by means of a metal transfer process. In this case, both the donor and the acceptor can be used (in very specific versions both). A single metal layer (eg opaque metallization) or several layers can be transferred (eg absorber and dielectric). The term "metal transfer" should not be understood in the literal sense as transfer only metallic layers, but also include an extension of the so-called method on layer systems with non-metallic layers (eg SiO ₂ , MgF, TiO ₂ ).

A particular advantage of the metal transfer method is that very high-resolution images are possible, for example, even high-resolution half-tone representations, such as portraits, or microtext with tiny font sizes. In this case, such a fine structuring or screening of a metal layer by means of the metal transfer process that very high-resolution grid with a line density of more than 150 lpi (lines per inch), preferably more than 200 lpi and more preferably more than 300 lpi and very fine line thicknesses with a line width of less than 100 microns for still visible text are possible.

So-called transparency / supervisory layers are characterized by the fact that a certain color impression is produced in the review. In the supervision, however, a different color impression, as can be achieved, for example, by overprinting with a more or less transparent lacquer / color layer, can be produced. For example, if you look at a film that is painted very thinly with transparent red paint, it will appear red, while when looking through this film, you may have a rather green color impression. The respective color complementary to the supervisory color is thus visible in the see-through (the spectrum of the transmitted light is the viewing-light spectrum minus the supervisory-light spectrum minus absorption). Something similar can also be produced by vapor deposition with a sequence of very thin alternating metallic and dielectric layers. It is also possible to create a defined supervisory / see-through effect with completely new color combinations, even a fluorescent or luminescent supervisory / see-through effect is possible.

If one deposits the thin-film element with a motif which consists of a fine metallization / demetalization or a more or less opaque color print (screened or not), a finely designed motif is obtained on a support. It results in review and supervision a different color effect, the subject of the one side and the opposite side is also not visible or in any other than the supervisory color. A rasterization is advantageous because it allows the execution of fine motifs and at the same time a high area coverage.

According to a further advantageous embodiment of the security element, it is provided that the color impression, which the raster elements have in plan view, corresponds to a color impression of the combination of thin optically active layers in a view and / or in plan view.

The thin-layer element in the form of an interference-capable, multilayer structure, which consists for example of an aluminum, a silicon dioxide and an aluminum layer can also be replaced by other effect materials, such as a printing ink with iriodin or pearlescent pigments from BASF.

The halftone printing can also be performed with ultraviolet or infrared active colors that are visible only in the ultraviolet or infrared wavelength range of electromagnetic radiation.

The embodiments and embodiments mentioned above and below are primarily aimed at covering an opening or a window in a banknote made of cotton paper. However, possible further embodiments are the design as transfer strips and the subsequent introduction within multi-layer substrates, such as, for example WO 2004/028825 A2 or off WO 2006/066431 A1 as well as the design as transfer strips and the application on polymer substrates with transparent window. The substrate thus preferably comprises paper and / or a film, in particular a translucent film. In the simplest case, the substrate is completely made of either paper or plastic. However, the substrate can also be made of different materials in some areas, and in particular in a range of paper and at the same time in another area made of plastic, preferably from a translucent film exist.

Within a substrate, more than one opening or window of a banknote can also be covered by a foil, which contains the embodiments and exemplary embodiments mentioned above and below. As a result, combinations of different effects within a banknote are possible.

Supervision in the context of this invention is illumination of the security element from one side and viewing of the security element from the same side. Supervision in supervision is thus present, for example, when the front of the security element is illuminated and also viewed.

A viewing in the sense of this invention is a lighting of a security element from one side and a view of the security element from another side, in particular the opposite side. A viewing in review is thus, for example, when the back of the security element illuminated and the front of the security element is considered. The light thus shines through the security element.

Reference to the following embodiments and the additional figures, the advantages of the invention will be explained. The embodiments represent preferred embodiments, to which, however, the invention should not be limited in any way. Furthermore, the representations in the figures of better understanding are highly schematized and do not reflect the realities. In particular, the proportions shown in the figures do not correspond to the conditions present in reality and serve exclusively to improve the clarity. Furthermore, the embodiments described in the following embodiments are better understood because of reduced to the essential core information. In the practical implementation much more complex patterns or images can be used.

Fig. 1

ein erfindungsgemäßes Sicherheitselement gemäß einer ersten beispielhaften Ausgestaltung in zwei verschiedenen Ausführungsformen (Fig. 1a und Fig. 1b),

Fig. 2

ein erfindungsgemäßes Sicherheitselement gemäß einer zweiten beispielhaften Ausgestaltung in drei verschiedenen Ausführungsformen (Fig. 2a, Fig. 2b und Fig. 2c),

Fig. 3

ein erfindungsgemäßes Sicherheitselement gemäß einer dritten beispielhaften Ausgestaltung,

Fig. 4

ein Bildelement als unterbrochene Fläche in Form einer Grafik und hierbei in Fig. 4a in positiver Darstellung und in Fig. 4b in negativer Darstellung.

In detail, show schematically:

Fig. 1

an inventive security element according to a first exemplary embodiment in two different embodiments ( Fig. 1a and Fig. 1b )

Fig. 2

an inventive security element according to a second exemplary embodiment in three different embodiments ( Fig. 2a, Fig. 2b and Fig. 2c )

Fig. 3

an inventive security element according to a third exemplary embodiment,

Fig. 4

a picture element as a broken surface in the form of a graphic and here in Fig. 4a in positive presentation and in Fig. 4b in negative representation.

Fig. 1 shows in Fig. 1a a carrier film 1, which is for example a PET film, on which an aluminum-colored grid of raster elements 2 is applied. The aluminum-colored grid can in this case vapor-deposited over the entire surface of the carrier film 1 and then, for example, by a washing process, as for example WO 99/13157 A1 is known to be partly demetallized again, so that the raster elements 2 remain on the carrier film. Alternatively, the raster elements 2 can also be printed directly onto the carrier foil 1 by means of conventional printing methods known from the prior art.

On the grid, a thin-film element 3 is arranged in the form of an interference-capable, multi-layered structure. By way of example, the thin-film element 3 has a three-layer structure and consists of an aluminum layer, a silicon dioxide layer and an aluminum layer. This thin-film element 3 appears in a top view in a golden and in a blue shade.

A viewer sees in supervision, seen from above on the security element, the seemingly homogeneous gold surface of the thin-film element 3, the raster image is not or only very slightly visible. (In the case of such a thinned lower aluminum layer of the thin-film element 3, so that the thin-film element 3 is no longer opaque, but translucent, in plan view, the raster elements 2 are slightly recognizable through the thin-film element 3.)

Seen in plan view from below on the security element, the raster image appears aluminum-colored against the golden background of the thin-film element 3.

In review, the raster image appears dark against a blue background.

Fig. 1b shows a variant in which a grid of gold-colored raster elements 4 on one side of the carrier film 1 and the thin-film element 3 in the form of an interference-capable, multi-layered structure on the opposite side of the carrier film 1 is arranged. The color of the raster elements 4 is in this case selected so that it corresponds to the color of the thin-film element 3 in plan view.

It results in supervision, seen from above on the security element, a seemingly homogeneous gold surface. In supervision, seen from below on the security element, a homogeneous gold surface appears, the raster image is not visible. In review, the raster image appears dark against a blue background.

In addition to the demetallization of the layer structure according to Fig. 1a or Fig. 1b In addition, a shaping of the supervisory / transparent layer can take place, which can be integrated by design with the grid layer. In this case, design elements of the image-forming screening and the transparent area gold / blue are arranged in register or offset. Also logically complementary structures are possible, such as screened gold color printing outside the coating area, which continues under the coating. For example, an image that appears in a plan view with a golden, screened frame and a golden inner surface changes to a black-rastered frame and a blue-shaded interior motif.

Alternatively, the application of the grid can be done by laminating a separate film. Particularly advantageous is a generation of the screening by a metal transfer method. For this purpose, for example, a first film ("donor") have the screening in the form of surveys (for example, embossed in an embossing lacquer). This donor sheet is then coated with a poorly adherent metallization (for example vapor deposition) and subsequently brought into contact with another sheet ("acceptor sheet") which is provided with a sticky surface (for example by coating with a sticky lacquer). If you then separate the two films, the metal is transferred to the surveys of the embossing on the acceptor. The metallizations on the acceptor and donor films have a positive or negative image of the same fine screening in principle both can provide a fine screening for the subject invention. The achievable feature sizes can be far below those that can be achieved with conventional printing methods (printing a color or wash), and be, for example, only a few microns.

Fig. 2 shows in Fig. 2a a carrier film 1, on which a grid of raster elements 5 is printed with a blue translucent color and thereon the thin-film element 3 is arranged in the form of an interference-capable, multi-layered structure. The color of the grid elements 4 is in this case selected so that it corresponds to the color of the thin-film element 3 in a transparent view.

It is shown in plan view, seen from the top of the security element, the golden surface of the thin-film element 3 and in plan view from below on the security element, a blue raster image in front of the gold-colored background of the thin-film element 3. In view, the raster image disappears and it shows up a homogeneous blue area.

According to Fig. 2b is arranged on a support film 1, the thin-film element 3 in the form of an interference-capable, multi-layered structure and thereon the grid of raster elements 5 in the blue translucent color of Fig. 2a printed.

In a plan view, viewed from above on the security element, a blue raster image in front of the gold-colored background of the thin-film element 3 and in plan view from below on the security element, the gold-colored surface of the thin-film element 3. The raster image vanishes in a transparent manner and results a homogeneous blue area.

According to Fig. 2c On one side of the carrier film 1, the thin-film element 3 is arranged in the form of an interference-capable, multi-layered structure and applied thereon a first grid of raster elements 5 in a blue translucent color. On the other side of the carrier film 1, a second grid of raster elements 5 is applied in a blue translucent color, which, however, represents a different pattern than the first grid.

In a plan view, seen from above on the security element, a blue raster image in front of the gold-colored background of the thin-film element 3 and in plan view, seen from below on the security element, another blue raster image in front of the gold-colored background of the thin-film element 3. Looking through from above or below both raster images vanish and a homogeneous blue area results.

According to Fig. 3 On one side of the carrier foil 1, a grid of opaque raster elements 7 is applied and on it the thin-layer element 3 is arranged in the form of an interference-capable, multi-layered structure. On the other side of the carrier film 1, a further thin-film element 3 is arranged in the form of an interference-capable, multilayer structure.

The grid can be printed in this case, for example in the form of a black color.

As can be seen in plan view, seen from above and from below on the security element, in each case the homogeneous gold-colored surface of the thin-film element 3. When viewed in phantom, the raster image appears dark against the blue background of the thin-film element 3.

Fig. 4 shows a picture element as a broken surface in the form of a graphic representation of the head of a female person. This represents the area from essentially opaque and transparent image parts, the person is a silhouette. Fig. 4a shows here a positive representation, ie dark parts of the picture in front of a bright background, and Fig. 4b a negative representation, ie bright parts of the picture against a dark background.

Claims (9)

1. Optically variable security element having a combination of thin optically effective layers (3) and which has, in reflected view, at least one first colour impression and, in transmitted view, at least one second colour impression, wherein the optically variable security element has an additional reflected-view/transmitted-view effect, wherein the optically variable security element comprises at least one arrangement of image elements, wherein the additional reflected-view/transmitted-view effect is produced by the at least one arrangement of image elements (2, 4, 5, 6) applied on at least one side of the optically variable security element, wherein the image elements (2, 4, 5, 6) are not light-diffractive or interference-producing microstructures, wherein, from a given side of the optically variable security element at a given viewing angle, the image elements (2, 4, 5, 6) are not visible in reflected view but are visible in transmitted view, or, from the given side of the optically variable security element at the given viewing angle, the combination of thin optically effective layers (3) is not visible in reflected view but is visible in transmitted view, characterized in that the combination of thin optically effective layers (3) is a thin-film element in the form of an interference-capable multilayer construction.
2. Optically variable security element according to Claim 1, characterized in that the image elements (2, 4, 5, 6) are implemented as grid elements.
3. Optically variable security element according to Claim 1 or 2, characterized in that the image elements (2, 4, 5, 6) are implemented as at least one continuous or interrupted area or line in the form of at least one alphanumeric character, a graphic or a pattern.
4. Optically variable security element according to at least one of the preceding claims, characterized in that the image elements (2, 4, 5, 6) consist of a printing ink.
5. Optically variable security element according to at least one of Claims 1 to 3, characterized in that the image elements (2, 4, 5, 6) consist of a metallic or metal-type coating.
6. Optically variable security element according to at least one of the preceding claims, characterized in that the colour impression exhibited by the image elements (2, 4, 5, 6) in reflected view corresponds to a colour impression of the combination of thin optically effective layers (3) in transmitted view.
7. Optically variable security element according to at least one of the preceding claims, characterized in that the colour impression exhibited by the image elements (2, 4, 5, 6) in reflected view corresponds to a colour impression of the combination of the optically effective layers (3) in reflected view.
8. Method for producing an optically variable security element according to at least one of the preceding claims, characterized in that the image elements (2, 4, 5, 6) are printed onto the at least one side of the optically variable security element.
9. Method for producing an optically variable security element according to one of Claims 1 to 7, characterized in that a washable ink is applied onto the at least one side of the optically variable security element, with the washable ink forming a pattern that is inverted with respect to the pattern of the security element, a cover layer is applied on top of the washable ink, and the at least one arrangement of image elements (2, 4, 5, 6) is produced by way of a washing procedure.

Images