Patent Application
20070246932
The invention relates to a data carrier with an optically variable structure, which has an embossed structure and a coating contrasting to the surface of the data carrier, wherein the embossed structure and the coating are combined such that at least parts of the coating are completely visible upon perpendicular viewing, but are concealed upon oblique viewing and when viewed from at least one predetermined viewing angle a first information is recognizable, which upon perpendicular viewing is not visible or only faintly visible.
For protection against imitation, in particular with color copying machines or other reproducing methods, data carriers, such as for example bank notes, papers of value, credit or ID cards, passports, deeds and the like, labels, packaging or other elements for the product protection, are equipped with optically variable security elements. The protection from forgery here is based on the fact that the visually simply and distinctly recognizable optically variable effect cannot be reproduced or only insufficiently reproduced by the above-mentioned reproducing devices.
For example, from CA 10 19 012 a bank note is known, which in a partial area of its surface is provided with a parallel printed line pattern. For producing the optically variable effect additionally a line structure is embossed into the data carrier in the area of this printed line pattern, so that flanks are formed, which each are visible only when viewed from certain viewing angles. By selectively arranging the line pattern on flanks of the same orientation, upon oblique viewing of the flanks provided with the lines these lines are visible, upon oblique viewing of the back of the flanks the line pattern is not recognizable. When in partial areas of the embossed area of the line screen or the embossed screen phase shifts are provided, then information is representable, which is only recognizable either when viewed from the first oblique viewing angle or when viewed from the second viewing angle.
With such an optically variable security element the tilt effect is very sharply defined, but occurs only in a very narrow viewing angle range. For the visual check of the known optically variable elements, therefore, exactly this viewing angle range must be found, so that these optically variable elements are less suitable for a simple visual check.
Therefore, it is the problem of the present invention to improve an optically variable security element with respect to its forgery-proofness and with respect to its visual checkability.
This problem is solved by the features of the independent claims. Advantageous developments are subject of the subclaims.
According to the invention the optically variable structure consists of a coating and an embossed structure overlapping this coating. The embossed structure has nonlinear embossed elements, which are combined with the coating such that when changing the viewing direction different pieces of information become visible. The nonlinear embossed elements are characterized in particular by at least three flanks, these flanks having dimensions permitting the shadowing effect according to the invention. I.e., the flanks must be dimensioned such that for a viewer, who views such a flank, an information lying behind this flank at least partially is concealed. The flanks of the nonlinear embossed elements thus form plane or curved areas, which either constantly merge into one another, as it is the case for example with surface areas of rotationally symmetrical, three-dimensional forms (e.g. segments of a sphere, frustums of a cone) or abut under a certain angle, as it is the case for example with polygonal three-dimensional forms (e.g. pyramids, tetrahedrons). The nonlinear embossed elements can have flanks of plane and/or curved areas, in particular the embossed elements can have e.g. the form of n-sided pyramids, tetrahedrons, frustums of a pyramid, segments of a cylinder, cones, conic sections, paraboloids, polyhedrons, cuboids, prisms, sectors of a sphere, segments of a sphere, spherical segments, hemispheres, barrel-shaped bodies or tori. But the nonlinear embossed elements can also be formed as a so-called divided torus, wherein the torus is divided in parallel to that plane, in which lies the large radius of the torus. Especially preferred is the use of embossed elements in the form of segments of a sphere, or three- or four-sided pyramids. The nonlinear embossed elements preferably are tactile.
Moreover, the nonlinear embossed elements according to the invention have the advantage, that in a simple fashion more than two pieces of information can be placed in the optically variable element, which become visible under different viewing angles, since the nonlinear embossed elements have a plurality of flanks, on which the information or parts of the information can be disposed selectively and separate from each other.
Depending on form, height and dimension of the nonlinear embossed elements, special visual effects can be selectively produced. For example, nonlinear embossed elements in the form of pyramids or frustums of a cone with steeper flanks produce a more contrasting effect when tilted than e.g. nonlinear embossed elements in the form of flattened spherical segments with an equal embossing height.
An embossed structure with embossed elements tapered on the top normally renders the same information in a different appearance than an embossed structure with knobs flattened on the top, which e.g. form plateaux. However, pyramidal embossed elements or embossed elements in the form of spherical segments or hemispheres are preferred for the invention.
The nonlinear embossed elements may be disposed to each other in any fashion so as to thereby produce a certain embossed structure. At least a part of the embossed structure can consist of screenlike disposed nonlinear embossed elements. Here the nonlinear embossed elements constitute the screen dots.
The term “screen dots” shall be understood in the meaning as usual in printing technology. The screen dots have a superficial extent in the substrate level and are not point-shaped in a mathematical sense. The employed analogy exists between the dot size (or superficial extent) of the screen dots and the base of the nonlinear embossed elements in the data carrier level. Here the base of the nonlinear embossed elements in the data carrier level actually is a projection of the embossed element geometry into the data carrier level.
The following explanation follows the “Handbook of printing media” (“Handbuch der Printmedien”), Publishing House Springer, page 44 ff. Accordingly, screen dots can be disposed in a constant periodical screen, which means an arrangement with equal distances between the dots, equal dot sizes and an unvarying dot form over the entire screen. Due to the possibility to vary the dot size a so-called amplitude-modulated periodical screen is the result. A nonperiodical frequency-modulated screen of 1st order is present, when the distance between the dots is selected to be variable and dot size and dot form are selected to be unvarying. Both possibilities will result in advantageous embossed structures when applied for the arrangement of the nonlinear embossed elements.
A structure having screen dots with a variable distance between the dots, a variable dot size and an unvarying dot form is referred to as nonperiodical screen of 2nd order. It has been shown, that analogous to this an embossed structure can be produced which is also suitable for the invention.
Likewise, a screen is thinkable, wherein all three parameters may be varied and which is referred to as nonperiodical screen of 3rd order. An embodiment and arrangement of the nonlinear embossed structures analogous to this is also thinkable.
All these types of screens may be employed within the terms of the invention.
The coating of the optically variable structure can be a metal layer, a metallic effect layer or an optically variable layer, which is present in an all-over or a structured fashion on the object to be protected. Alternatively, the coating can be any, preferably printed, geometric pattern. The coating may be formed of differently colored basic pattern elements, such as lines, triangles etc. These basic pattern elements may be disposed as a result of chance, but may be selected with regard to their dimensions such that the viewer perceives the coating as a homogeneous colored surface.
The basic pattern elements may also have at least one colored surface, geometric patterns, alphanumeric characters or any image motifs. The different colored surfaces and/or pieces of information of the basic pattern element here preferably are disposed on different flanks of the nonlinear embossed element, so that the individual colored surfaces and/or pieces of information become visible from different viewing angles.
Alternatively, the basic pattern elements may also represent a part of any printed image, such as a guilloche pattern or an image motif. For example, in the case of a multicolored guilloche pattern the basic pattern elements may constitute crossing points of the guilloche lines. The basic pattern element here consists of differently colored line segments crossing each other, the length of which is determined by the nonlinear embossed element disposed in this area.
In the simplest case, however, the basic pattern elements form the screen dots of a preferably printed screen.
Therefore, according to a first embodiment of the optically variable structure, embossed structures and coating have the form of a screen. The screen elements of the coating are formed by basic pattern elements, each of which has three individual elements in the colors red, green and blue. The individual elements have the form of triangles or circle segments.
The screen elements of the embossed structure have the form of three-sided pyramids, which constitute the nonlinear embossed elements. To each pyramid is allocated a basic pattern element, the differently colored individual elements of the basic pattern element are disposed on different flanks of the pyramid and the individual color components of the basic pattern elements are disposed on the flanks of the same orientation. The individual elements of the basic pattern element have the same size and all basic pattern elements of the coating have the same structure, so that upon perpendicular viewing of the optically variable structure the coating appears nearly white.
When rotating and/or tilting this optically variable structure, the portions of the basic pattern elements, which are disposed on the flanks of the pyramids that are facing away from the viewer, will be concealed. Since these portions no longer contribute to the color effect of the coating, the viewer perceives a color different than white. In the ideal case the viewer exclusively views the flanks of one color, so that the perceivable color effect changes from red to blue or green. Since the transitions depending on the viewing angle are rather indistinctly, the viewer perceives a rainbow effect. This interplay of colors is well visible for the viewer without using any aids and therefore forms a simply checkable authenticity feature. At the same time such a security element is imitable only with great effort due to the embossed structures used and the necessary guiding in register of coating and embossed structure. It therefore offers a high degree of protection from forgery.
Special optical effects can be achieved according to the invention by a variation of the form of the nonlinear embossed elements, the embodiment of the coating, variations of the arrangement of the nonlinear embossed elements and/or the coating as well as the color selection for the coating.
In the embodiment described above additional information can be produced for example by varying the coating, e.g. by omitting individual screen elements, or a variation of the form of the screen elements. Alternatively, the coating screen remains the same and the screen of the embossed structure is varied. In certain areas the nonlinear embossed elements can be disposed offset to the surroundings. A further possibility is to continuously vary the distances between the nonlinear embossed elements, i.e. the screen ruling of the embossed structure, so that with respect to the coating screen a beat occurs. Likewise, individual nonlinear embossed elements may be omitted or the form of the nonlinear embossed elements may be varied.
The combination of a basic pattern element with a nonlinear embossed element in the following is referred to as “structural element”. In the example described above the combination of pyramid and three-color basic pattern element forms the structural element.
According to a further embodiment the basic pattern element of the structural element may have for example only one colored area, which is disposed on one of the flanks of the nonlinear embossed element. The remaining flanks of the nonlinear embossed element show the color of the embossed background, e.g. the white color of a paper of value. In this case when tilting and/or rotating the security element the viewer perceives an interplay between the different brightness steps of the employed color. When viewed from certain viewing angles the viewer possibly perceives only the color effect caused by the unprinted paper.
Such structural elements may also be designed in any elaborate and complicated fashion, as a result of which the protection from forgery is increased. The structural elements may be designed and disposed such, that in incident light no information is recognizable and the information is not visible until viewed under certain viewing angles. Here the coating can be single-colored, so that all recognizable pieces of information have the same color. Upon perpendicular viewing a mixed color may be recognizable. Upon oblique viewing various pieces of information in different colors become recognizable.
According to a further preferred embodiment the structural elements may be designed such that upon perpendicular viewing of the optically variable structure a multicolored image motif is recognizable, the visual effect of which, however, varies with a change of the viewing angle. This variation here ranges from a pure color change to a change of the image information represented.
In a special embodiment the structural elements correspond to the image points of a multicolored image motif, to which are allocated certain color components of a primary color system. The color components allocated to the respective image point form the basic pattern element, which is combined with an appropriate nonlinear embossed element. The total area allocated to the basic pattern element here preferably is divided into areas, which are occupied by the respective colors of the primary color system. The color effect of the basic pattern element here results from the size of the areas occupied by the respective colors. These areas may directly adjoin each other or may be disposed in overlap. The colored areas do not have to fill out the total area of the basic pattern element. In this case the color effect of the basic pattern element is also influenced by the color of the background.
If, for example, the primary color system consisting of cyan, magenta and yellow is used, in the total area intended for the basic pattern element three colored areas are provided, which are disposed such, that each of the colored areas comes to lie on a respective flank of the employed nonlinear embossed element. Upon oblique viewing or when rotating such an optically variable structure individual color components of the image information are concealed by the nonlinear embossed elements, so that the image information appears in a mixed color consisting of the colored areas of the basic pattern elements lying in viewing direction.
If the nonlinear embossed element for example has the form of a segment of a sphere, the three colored areas of cyan, magenta and yellow, which preferably have different sizes, are located on the round surface area of the embossed element. The structural element in this case consists of an embossed element in the form of a segment of a sphere, on the surface area of which are disposed differently sized colored areas of cyan, magenta and yellow, that when rotating the structural element around its axis of symmetry the different colors successively become visible. As to be able to produce an optically variable structure out of such structural elements, which upon perpendicular viewing show a colored image information, the sizes of the colored areas have to vary from structural element to structural element.
For the colored areas not necessarily primary colors have to be used, instead any color systems depending on the desired effect may be used.
It shall be explicitly pointed out, that even with less ordered embodiments, in which the repeating of the basic pattern elements and the frequency of recurrence of the embossed structure are not equal or there is no repeating at all, there can be produced interesting optically variable structures within the terms of the invention. The coating can have, for example, differently colored geometric structures as a basic pattern element, which, however, are disposed in a disordered fashion as a result of chance.
In an advantageous development of the invention the nonlinear embossed elements in their dimensioning are designed such that they produce a tactile structure well perceivable for men. The tactilely perceivable optically variable structure offers an additional protection against imitation by color photocopying or scanning the data carrier.
The optically variable structure can have an additional information, which results from a variation of the coating and/or the embossed structure. For example, the additional information can result from a variation of form, size or height of the nonlinear embossed elements. Likewise, a variation of the arrangement of the nonlinear embossed elements, such as an offset in certain areas or a change of the screen ruling in certain areas or omitting individual or a plurality of nonlinear embossed elements, is thinkable. If the coating in the area of an information is varied, this can be effected for example by a variation of form or color of the coating. Here, too, it is obvious that a variation of the arrangement of the coating is possible, such as for example an offset, a change of the screen ruling, reflection or omitting individual or a plurality of basic pattern elements.
The embossed structure additionally can be divided into partial areas, in which are disposed different partial embossed structures. Preferably, the partial embossed structures in at least two partial areas adjoining each other are disposed in an offset manner by a fraction of the screen ruling, in particular offset by one third of the screen ruling. For a better perceptibility parts of the partial embossed structures can have an unembossed edge contour.
In connection with this matrix-like arrangement of the partial embossed structures as well as the production of additional information in the area of the embossed structures or the coating explicit reference is made to WO 97/17211 and WO 02/20280 A1.
The optically variable structure according to the invention forms a security element difficult to imitate and can be directly disposed on any data carrier. The optically variable structure can also be part of a security element, which beside the optically variable structure has further security features.
The security element, for example in the area of the optically variable structure, can have a further ink layer, which preferably is translucent and disposed congruent to the raised areas of the embossed structure. Here, too, most different embodiments are possible. Some are already described, for example, in WO 2004/022355 A2, to which in this connection explicit reference is made likewise.
According to a further embodiment the security element may have further layers or authenticity features, such as e.g. a metallic layer, an additional translucent optically variable layer or a foil element. The optically variable structure may be overlaid or underlaid with such layers or elements.
Furthermore, it is also possible that the coating or printing inks used for the production of the basic pattern elements and/or the ink layer congruently disposed to the raised areas of the embossed structure at least partially are provided with machine readable properties. For this purpose magnetic, electrically conductive, luminescent additives are suitable.
The optically variable structure according to the invention or the security element according to the invention preferably is applied onto data carriers, such as for example security documents and documents of value, such as bank notes, share certificates, bond certificates, deeds, vouchers, credit cards or ID cards, passports or the like. In this way the data carriers are provided with a security element which even for laymen is easy recognizable as to increase the forgery-proofness. But the optically variable structure or the security element according to the invention also very advantageously may be used in the area of product protection. Here the optically variable structure or the security element can be applied to respective labels or packaging or directly onto the goods.
If paper is used as a data carrier material, in particular cotton vellum papers, paper-like materials consisting of plastic foils, paper coated or laminated with plastic foils or multilayer composite materials are suitable.
For producing the security element according to the invention or the optically variable structure preferably any desired substrate at first is provided with the coating and subsequently in register to this coating the embossed structure is produced. In principle it is also possible that the procedure steps are provided in reverse order. Here the coating preferably is printed or transferred to the substrate by the thermal transfer method. The coating can be produced with any printing method, such as for example by planographic printing, e.g. by offset method, by relief printing, e.g. by letterpress printing method or flexographic printing method, by screen printing, by gravure printing, e.g. by halftone gravure or intaglio printing, or by a thermographic method.
For producing the embossed structure any desired methods are thinkable likewise. Preferably, the embossed structure is produced by means of an embossing tool, which for example may be an intaglio printing plate. Here the embossing is produced as a blind embossing with the help of an inkless intaglio printing plate. But according to a special embodiment the embossed structure likewise can be produced by means of ink-carrying intaglio printing. This manufacturing variant in particular is suitable for those embodiments, in which a further ink layer congruent to the embossed structure is provided.
For producing the embossing tool, for example, a plate surface is milled with a graver or a laser. As a plate surface any material such as copper, steel, nickel or the like can be used. The graver used for the milling preferably has a flank angle of about 40° and a rounded head approximately the form of a spherical segment or spherical sector. The embossing tool can be milled as a single copy or already as a multiple-copy sheet.
In principle the order of the two procedure steps can be selected in any fashion. Normally at first the coating is applied and then it is embossed. With that the relief height and the form of the embossing is spared further influences, which for example may occur in a subsequent printing process. The alternative, namely to emboss at first and to apply the coating afterwards, however, offers the advantage of a higher color brilliance and a sharper contour of the print. This effect is caused by the fact that the substrate during the embossing process at the same time is calendered and thus a smoother, less absorbent surface is obtained.
With reference to the following examples and complementing Figures the advantages of the invention are explained. The described individual features and embodiments described in the following are inventive when taken alone, but also in combination are inventive. The examples represent preferred embodiments to which, however, the invention shall not be restricted in any fashion. The proportions shown in the Figures do not correspond to the dimensions present in reality and exclusively serve for the improvement of clarity.
In the Figures the following is schematically shown:
a,b show an embossed element in the form of a tetrahedron,
a,b show a four-sided pyramidal embossed element,
a,b show an embossed element in the form of a frustum of a pyramid,
a,b show an embossed element in the form of a frustum of a cone,
a,b show an embossed element in the form of a cylinder segment,
a,b show an embossed element in the form of a torus,
a,b show an oval embossed element,
a,b show a drop-shaped embossed element,
a-g show various embodiments of the embossed structure according to the invention in top view,
The optically variable structure 3 can be of different design resulting in the different effects from different viewing directions. According to a preferred embodiment the optically variable structure 3 consists of a single-colored or multicolored coating contrasting to the surface of the data carrier, such as a pattern, image or an alphanumeric information, which is produced by printing or in another way, such as for example by means of a transfer method. The effects according to the invention usable for determining the authenticity are produced by the embossed structure cooperating with the coating depending on the structure of coating and embossed screen and their mutual allocation.
All structures according to the invention have in common that they and the effects resulting thereof cannot be imitated with the help of reproduction techniques known today, in particular copying machines, since the copying machines can reproduce the optically variable structure only from one viewing direction, so that the optically variable effect is lost.
In the following, examples of various preferred embodiments of the invention will be explained with reference to the Figures. The representations in the Figures are greatly schematized for clarity's sake and do not reflect actual constructions.
The embodiments described in the following examples are reduced to the essential core information for clarity's sake. In practical application substantially more complex patterns or images in single-color or multicolor printing can be used as a coating. The same applies to the embossed structures. The information represented in the following examples can likewise be replaced by image information or text information as elaborate as desired. For producing the coating, e.g. as an imprint, usually the possibilities of the printing technology are exploited. Typically, pattern elements with minimum diameters of 10 micron are used. The nonlinear embossed elements, which form the embossed structure, as a rule have an embossing height in the range of 20 to 250 micron and preferably a diameter in the range of 40 to 1000 micron.
The various embodiments are not restricted to being used in the described form, but can also be combined with one another to enhance the effects.
Furthermore, in the following examples only design and mutual coordination of the embossed structure and the coating are shown, so as to illustrate the optical effects of the optically variable structure according to the invention.
That the nonlinear embossed elements 5 are designed as elevations, which preferably are produced by embossing the data carrier, is clearly recognizable at the top side of the data carrier as shown in the sectional view. If the data carrier is mechanically shaped with an embossing tool the bottom side of the data carrier material shows the negative deformation. The deformation here is only schematically represented. The back of the data carrier normally will not have an embossing as distinct and true to the embossing tool. In the following only the top side or front side of the data carrier, which are essential to the understanding of the invention, are viewed. The deformation of the bottom side or back is not essential to the invention, but only a concomitant of special embossing techniques, such as e.g. intaglio printing. But it can serve as a further authenticity feature.
In
From the viewing direction selected in
The above described principle can also be used for more complicated pieces of image information. Here two or a plurality of images are divided into individual image points, which are disposed in such a way that the image points belonging to one image come to lie on the flanks of the same orientation. Depending on the embodiment upon perpendicular viewing only a surface of uniform color or a complete information is recognizable. Upon oblique viewing the individual images become visible.
The embossed structure 4 alternatively can have embossed elements of any other geometric shape, with each of which one special form of the effect being achieved. For example embossed elements in the form of pyramids or frustums of a cone with steeper flanks render a more contrasting effect when tilted than e.g. embossed elements in the form of flattened segments of a sphere with the same embossing height.
A selection of possible geometries for the nonlinear embossed elements is shown in
For security paper, such as for example cotton vellum paper, nonlinear embossed elements in the form of segments of a sphere with a diameter in the range of 40 to 1000 micron, in particular between 100 to 600 micron, especially preferred between 470 to 530 micron, have proved to be particularly advantageous. The embossing height here is in the range of 20 to 250 micron, in particular in the range of 50 to 120 micron.
For the width and embossing height of oval embossed elements applies the same, with respect to the length dimensions of up to 2 centimeter have been successfully used.
Depending on the substrate material, such as thin paper or thick cardboard, plastic materials and plastic composites, such as paper laminated or coated with plastics or multilayer composite materials, certain forms and dimensions of embossed elements may be particularly advantageous. The advantageous ranges of values here actually may considerably differ from the values ascertained for security paper.
The production of the nonlinear embossed elements preferably is effected by mechanical shaping the data carrier material. For this purpose an embossing tool according to the invention is employed, which is manufactured with an engraving tool according to the invention. Until now a graver has proved to be especially suitable, the head of which is adjusted to the special requirements by the head being flattened. This adjusted engraving tool preferably has a flank angle of about 40°.
The producible geometries of the embossed elements are dependent on the employed engraving tool. If instead of a graver for example laser engraving is selected as a method for producing the embossing tool, geometries of embossed elements can be produced which have side faces perpendicular to the data carrier level. For example cylindrical embossed elements can be produced with the help of laser engraving.
Upon perpendicular viewing depending on the dimension of the rectangular areas the viewer again perceives a uniform plane color effect or directly the rectangular areas. When rotating and/or tilting the data carrier again an interplay of colors emerges.
A further variant of the principle according to the invention explained in example 2 is shown in
A basic pattern element is composed of four triangles, wherein in each of the triangles is disposed an image part of one of the four images. The triangle referred to as “1” belongs to the image recognizable under viewing direction 1, the triangle “2” to the image recognizable under viewing direction 2 etc.
If all image parts are represented in the same color, upon perpendicular viewing no image information whatsoever is recognizable. In the case of a colored embodiment an image information is possibly recognizable, which however differs from the images recognizable under the different viewing directions.
By a special design of the coating and/or the embossed structure into the optically variable structure 3 can be incorporated an additional information, which in a viewing direction perpendicular to the data carrier level is not visible or only very faintly visible, upon oblique viewing, however, it is easily recognizable for the viewer. This information cannot be reproduced with the conventional reproduction techniques and thus enhances the forgery-proofness of a data carrier equipped in such a way.
Example 4 describes the incorporation of such an information 14 into the optically variable structure 3 by variation of the coating 7.
The basis is the coating 7 according to example 1, wherein for individual structural elements 10 the arrangement of the circles 8 and rectangles 9 has been altered. In
The
By a respective design and arrangement of any desired number of such altered structural elements, information of any design is representable. For example letters, company logos, check digits or decorative elements can be incorporated as an information. The coating in the area of individual structural elements can also be completely omitted or can be replaced by any pattern or information contrasting to the surroundings.
This example shows the incorporation of an information by variation of the embossed structure.
In the perspective representation of
A further possibility to form an information 16 by variation of the embossed structure 4 is shown in
In the field of product protection and in the field of packaging due to the substrates employed, such as plastic foils, cardboards or paper with properties strongly varying from the security paper, completely different embossed element geometries may prove to be advantageous, in particular substantially longer oval embossed elements are thinkable. In the field of packaging also patterns with a higher number of colors are widely used, which for example are produced by 8-color-printing.
As explained above, the embossed structure 4 of the coating 7 is overlaid.
In this example an information is produced by offsetting the nonlinear embossed elements.
The coating 7 is identical with the coating explained in example 1 and consists of basic pattern elements, which each contain one colored square 9 and one colored circle 8. The embossed structure consists of embossed elements 5 in the form of segments of a sphere.
A further possibility for producing an information is the rotation of not rotationally symmetrical forms of embossed elements, such as e.g. an embossed element in the form of a spherical segment.
One development provides to combine the rotation of the nonlinear embossed elements with a shift, i.e. an offset. The result is a wide range of possible partial embossed structures for incorporating an information.
In
a shows the periodical arrangement of segments of a sphere of example 1. The embossed elements 5 here are disposed at a distance. The distance may be very short, for example less than 10 micron. Especially advantageously is a distance of 2 micron between the embossed elements. Since for such a short distance the embossing tool cannot be produced with the conventional etching technology, this embodiment further enhances the forgery-proofness of the optically variable structure.
Any desired longer distances may be employed likewise. Preferred distances here are 10 to 300 micron.
b shows an arrangement of embossed elements which with regard to gaps are placed as close together as possible.
c shows an arrangement wherein segments of a sphere with a large and a small base diameter are disposed alternately. For example in the area, which takes up the base of a large embossed element 5, there is space for four small embossed elements 20.
d alternately shows embossed elements 5, 21 with a circle area and a rectangular area as a base.
e shows oval embossed elements 18 alternating with embossed elements 5 in the form of segments of a sphere. Here in the longitudinal extent of one oval embossed element 18 two embossed elements 5 are provided. In principle the oval embossed element 18 is a deformed embossed element, which originally had the form of a segment of a sphere, which has been stretched or compressed in a preferred direction.
f and g show an embossed structure, wherein the embossed elements 5 in certain areas are disposed in overlap with each other, i.e. the embossed elements for example were engraved in an overlapping fashion or into each other when producing the embossing tool, so that an embossed structure in the form of a range of hills is the result.
It has been shown, that information, which is produced via a variation of the embossed structure, upon perpendicular viewing is hardly recognizable, so that in this way hidden information can be produced. Whereas changes in the coating upon perpendicular viewing normally are slightly perceptible.
A further improvement of the effect can be achieved by a suitable combination of the two possibilities for incorporating information.
The coating 7 preferably has the form of a printed pattern and likewise offers' a wide range of variation possibilities.
The partial pattern area B is produced by shifting the basic pattern by one side length of the square in vertical and horizontal direction. In this way a first information can be represented in the optically variable structure, which under certain viewing directions is visible. An interchanging of the rows and columns of the basic patterns results in a partial pattern area C, in which is represented a second information, which is well visible from another viewing angle range. The limiting lines 22 here only serve for clarity's sake, so as to be able to clearly optically separate the individual partial pattern areas A, B, C from each other.
Additionally, further partial pattern areas can be produced e.g. by a further shift by a fraction of side length of the square.
It has been shown, that by integrating a free, i.e. not or only transparently printed or coated, substrate area into the pattern, a very lively and striking interplay of colors is produced, wherein the viewer can see the information particularly well.
In combination with a suitable embossed structure a complex optically variable structure is provided, which shows to the viewer various pieces of information in a plurality of various viewing angle ranges. A periodical embossed element arrangement suitable for this is shown in
For illustrating the different visual impressions given by the various partial pattern areas (A, B and C) from an exemplary viewing direction BE,
The stripe pattern 37 likewise can have a structure of curved lines and/or can be designed in a multicolored fashion. A pattern containing guilloches is also suitable for the invention.
A further advantageous variation of the coating is a reduction or enlargement of the size of the individual colored areas of the pattern belonging to the basic pattern element, wherein preferably the pattern repeat is not changed in its dimensions. It has been shown, that in this way a very strikingly color-changing, optically variable element can be produced.
The coating according to the invention according to a further embodiment instead of a simple geometric pattern can be a complicated image, which preferably is printed by multicolor printing.
It is obvious that all other imaginable color systems as well as any colors or lacquers can be employed. Instead of individual color components or all color components special lacquers can be used, which produce dull or glossy areas. An integration of dull-gloss-effects into the print may even intensify the effect of the optically variable structure. The colored areas of the basic pattern elements alternatively may also be disposed in an overlapping and/or asymmetrical and/or random-generated fashion.
With this embodiment, by especially selecting the geometry of the nonlinear embossed elements smooth and sharp transitions between the pieces of information are produced, which are visible under the various viewing angles.
When on the pyramidal embossed elements a single-colored image motif and on the spherical segments a multicolored background motif is disposed, upon rotating and/or tilting the security element the single-colored image motif abruptly appears and vanishes in front of a colored background, which smoothly changes from one color to another and shows, for example, a rainbow effect.
In this embodiment the coating 7 consists of a single-color all-over background print 53, which has gaps 54 in the form of semicircles. This coating is combined with an embossed structure in the form of segments of a sphere 55, wherein the cut surfaces 56 of the segments of a sphere 55 coincide with the gaps 54 (
The gaps of course can have any form. The coating can also be a metal layer, which is transferred to an appropriate substrate by transfer method.
Preferably, the optically variable element is produced by printing technology. For this the coating is printed onto a substrate, preferably the document material, by any desired printing method, preferably by offset printing, and then this coating is appropriately embossed with an embossing tool. As an embossing tool here preferably an intaglio printing plate is used. This proceeding is represented in
The background layer 45 can also have the form of information and patterns. Special printing inks may also be used, which further enhance the antiforgery effect of the optically variable element. These can be optically variable printing inks, such as printing inks containing interference layer pigments or liquid crystal pigments, or metal effect inks, such as gold effect inks or silver effect inks.
Alternatively, the background 45 likewise can be applied by means of another method, for example in a transfer method, in an all-over fashion or provided with gaps or a pattern. By the transfer method also metallic pattern elements or coatings can be applied.
The background layer 45 can also be completely omitted, such as shown in
Preferably, for the ink layer 46 an at least translucent ink is used. The ink-carrying intaglio printing in an adaptation can be executed such that an inking takes place only on the nonlinear embossed elements, the valleys between the nonlinear embossed elements however remain free of ink.
In a development for the ink layer 46 an ink with machine readable additives, such as for example luminescence substances, can be employed.
This example describes an alternative for producing the optically variable element, wherein at first the substrate material is embossed and then the embossed area is provided with the coating.
The marking device 47 additionally or alternatively to the ink jet print heads can have one or a plurality of laser scan heads, which write pattern elements individually selectable for each place on the embossed structure, e.g. the letters A, into the substrate of the data carrier or into a coating by applying the energy of the laser beam.
The guiding in register between embossed structure and coating can also be effected by means of register marks or by using a device for imaging and image processing. For this purpose for example zeniths or valleys of embossed elements have to be captured by the imaging and image processing device, and their positions have to be made available as input values for the control unit of the marking device.
According to
Alternatively, of course also the substrate 100 can be moved.
Since coating and embossed structure are produced separately from each other, there is always the danger of fluctuations in register, which lead to the fact that the coordination between embossed structure and coating represented as ideal embodiments in the Figures cannot always be met. But since the optically variable effect still occurs in a well visible manner, of course these embodiments are also included by the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102004039595.0 | Aug 2004 | DE | national |
| 102005011612.4 | Mar 2005 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP05/08758 | 8/11/2005 | WO | 2/13/2007 |
