EP2795377A1

EP2795377A1 - Optically variable surface pattern

Info

Publication number: EP2795377A1
Application number: EP12813761.9A
Authority: EP
Inventors: Christian Fuhse
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2011-12-19
Filing date: 2012-12-17
Publication date: 2014-10-29
Also published as: WO2013091819A1; DE102011121653A1

Abstract

The invention relates to an optically variable surface pattern comprising a substrate which has a surface region (13) having a plurality of reflective pixels (14) arranged in rows and columns and aligned in such a way that when a viewer tilts the surface pattern (10) about a first axis, at least three bright-dark pattern representations are discernible in various positions, resulting in a pattern movement that comprises a movement along a first direction which forms an angle of less than or equal to 30° with the first axis, and/or a pattern rotation, wherein at least one of the rows and/or at least one of the columns contains pixels which produce the bright areas of at least two of the pattern representations.

Description

O p t i s c h a p a r i a b a n c e m e n t s

The present invention relates to an optically variable area pattern, the use of such area pattern as a master for producing volume holograms or as a security element, a value document having such an optically variable area pattern and a method for producing such an optically variable area pattern. Items to be protected are often provided with a security element that allows verification of the authenticity of the item and at the same time serves as protection against unauthorized reproduction.

Items to be protected include, for example, security papers, identity and value documents (such as bank notes, chip cards, passports, identification cards, identity cards, shares, attachments, certificates, vouchers, checks, tickets, credit cards, health cards, etc.) as well as product security elements (such as Labels, seals, packaging, etc.). It is known to design such an optically variable area pattern such that when tilted about a first axis, an orthoparallactic movement of a (complex) motif, such as a logo or a value, occurs. This is realized with a moiré magnification arrangement in which the motif is arranged periodically on a very fine grid (period of about 20 μm) and enlarged by means of a lenticular grid with the same period turned to a fine grid.

However, the technique of moire magnification arrangement has a number of technical disadvantages. Since the motif and the microlenses or their radii of curvature can not be arbitrarily small, a relatively large thickness of the optically variable surface pattern of typically more than 30 μιη necessary. If the optically variable surface pattern is used as a security thread, this thickness is disadvantageous since, for example, the embedding of such comparatively thick threads, in particular in banknote paper, is more difficult than the embedding of thinner threads. The embedding of the threads is also impaired by the fact that the lenses of Moire- magnification arrangement is not coated with adhesive and the threads thus at least in the usual unregistered insertion can thus only be coated on one side with heat sealing enamel. This can also lead to difficulties in embedding (eg wrinkling) and the resistances, since the paper webs are not firmly connected to the thread.

Furthermore, in the Moire enlargement arrangement, embossed patterns must be produced on two sides of the thread: one side with lenses and one side with microimages. This leads to a complicated production.

Furthermore, the image and lenticular grids must be extremely precisely matched, as even small deviations in the raster lead to significant image distortions. An accurate registration of the enlarged motif, for example, to the edge of a security thread is extremely difficult. For a lenticular with a period of 20 μπι would, for example, an offset to the micro images of 10 μπι already move the enlarged motif by half its size. Thus, it is extremely difficult, for example, always represent a single value value in the middle of the security thread with vertical supervision.

Orthoparallaktische motion effects with micromirrors are essentially known in the form of moving lines or beams, as described for example in DE 10 2010 047250 AI. Here is a continuous change in the slope of adjacent mirrors. Such representations are very brilliant, however, only comparatively simple motifs, such as moving lines and pump effects, can be realized, since the adjacent micromirrors have a continuously varying slope. A surface area comprising a few micromirrors can therefore contain mirrors which shine brightly only within a narrow angular range. A point of light or a bar can only run over it once over such an area when tipping over and not run back when tipping further or be followed by another point or bar. For example, a bright circle can pump from the inside to the outside, but it can not move from left to right with the same size.

Proceeding from this, it is an object of the invention to provide an optically variable surface pattern, with which an orthoparallaktischer motion effect can be displayed for any motifs and which can be produced simultaneously with a very small thickness.

The object is achieved by an optically variable area pattern with a carrier having a surface area with a multiplicity of reflective pixels which are arranged in rows and columns and oriented in such a way that an observer tilts the area pattern about a first axis

can sequentially perceive such that a motive movement is imparted, which comprises a movement along a first direction, which includes an angle of less than or equal to 30 ° with the first axis, and / or a rotation of the motif, wherein in at least one of the lines and / or in at least one of the columns are pixels that produce the bright areas of at least two of the subject images. By means of this arrangement according to the invention of the pixels in the rows and columns, there is an interleaving of the different views in the surface area, which leads to the advantage that any desired complicated motifs can also be displayed. It is therefore possible to run successively different parts of the motif over the same section of the surface area. As a result of the interleaving, it is thus possible in particular to generate overlapping representations for fluid movements.

Since the optically variable areal pattern is formed with reflective pixels and thus does not require microlenses in the manner of a moiré magnification arrangement, the areal pattern can be formed with the desired small thickness.

The reflective pixels are designed in particular as specularly reflecting pixels. The pixels thus have one or more mirror surfaces which reflect incident light according to the laws of geometric optics. The mirror surface of the pixels is preferably formed as a plane mirror surface. However, it can also be curved. In the surface pattern according to the invention, pixels can be located in at least one of the rows as well as in at least one of the columns, which generate the bright areas of at least two of the motif representations.

The rows and columns of the reflective pixels are preferably perpendicular to each other and extend in a straight line. However, this is not mandatory. There may also be other angles between the rows and columns, and the rows and columns may extend in a non-linear fashion. For example, the rows and / or columns Wavy. It is essential that the rows and columns cover the surface area as completely as possible.

In the surface pattern according to the invention, the first direction may include an angle with the first axis that is less than or equal to 10 °. In particular, the first direction may coincide with or be parallel to the first axis. Since the first direction according to the invention includes at most an angle of 30 ° with the first axis, one can speak of a substantially orthoparallaktischen movement.

In the case of the optically variable surface pattern, the at least three light-dark motif representations can in particular be selected so that they can be converted into one another solely by rotation and / or displacement.

The reflective pixels are at least in the row direction (and preferably also in the column direction) not greater than 300 pm, preferably not greater than 100 pm and particularly preferably not greater than 40 pm. The dimensions of the pixels ensure that high-resolution representations can be realized in which a viewer can hardly or no longer perceive the pixel structure with the naked eye.

In the case of the optically variable area pattern, the bright areas in each light-dark motif representation can be generated in each case by identically aligned pixels. Furthermore, the light-dark motif representations may preferably be two-dimensional motif representations. These can lie in the plane of the surface area. However, it is also possible that they are visually visible in front of or behind the plane of the surface area. The alignment of the pixels that produce the bright areas in each light-dark motif representation is preferably chosen to be free from random variations for each light-dark motif representation. Thus, there is preferably no pseudo-statistical distribution of the orientation of the pixels for the bright areas of the respective light-dark motif representation.

Preferably, the light-dark motif representations each show the same motif or the same motifs except displacement and / or rotation.

Of course, it is also possible that the light-dark motif depictions show different motives. This can be used to link the subject movement with a change of subject. Thus, for example, During the movement the motive changes from a first motive continuously or also suddenly into a second motive.

In the surface pattern according to the invention, the dark areas of the light-dark motif representations can be formed by reflective pixels which have an orientation deviating from the reflective pixels of the bright areas. Furthermore, the reflective pixels in the dark subareas for each light-dark motif representation can each be oriented identically in such a way that a viewer sees the negative representation of the respective light-dark motif representation in another viewing or illumination situation.

In the surface pattern according to the invention, the dark subregions of the light-dark motif representations can be light-scattering embossed structures, in particular moth-eye structures, by light-diffusing structures, in particular diffractive matt structures, micro-hollow or micro-oil mirrors (which may, for example, have a diameter of 20 μm or smaller). randomly oriented micromirrors, darkly colored areas and / or specularly reflective areas may be wholly or partly formed.

Furthermore, in the surface pattern according to the invention in an east-west tilting a stereographic depth effect by a horizontal image shift and in a north-south tilting, the movement along the first direction and / or the rotation arise.

In the surface pattern according to the invention, the surface region can be divided into at least two subregions in which the respective movement direction and / or associated tilting axis of the light-dark motifs are different. This can e.g. be used by the fact that the two sub-areas represent opposite directions of movement of the light-dark motifs with the same tilting direction. Furthermore, mutually perpendicular directions of movement of the light-dark motif representations can be generated in the two subregions with the same tilting direction.

In the surface pattern according to the invention, the two partial areas may at least partially overlap.

The dimensions of the micromirrors are preferably between 3 μπι and 300 μπι, in particular between 3 μπ \ and 100 μπι and more preferably between 5 μπι and 20 μπι. The carrier of the optically variable surface pattern may be formed in one or more layers. In particular, the carrier may comprise a film and / or a paper. As a material, for example, a plastic or a polymer material can be used. In particular, an achromatic representation can be realized with the optically variable surface pattern according to the invention.

In addition, the optically variable surface pattern can in particular be designed in such a way that, when the surface pattern about the first axis is tilted, a viewer can perceive at least five or at least ten light-dark motif representations at different positions successively in such a way that a motif movement is imparted that at least one Orthoparallaktische component has.

Furthermore, an optically variable areal pattern is obtained with a carrier having a surface area with a large number of reflective pixels which are arranged in rows and columns and oriented in such a way that, when the areal pattern is tilted about a first axis, a viewer sees at least three light-dark areas. Can perceive motif representations at different positions in succession so as to impart a motive movement having at least one orthoparallactic component, wherein in at least one of the rows and in at least one of the columns, there are respectively pixels that represent the bright areas of at least two of the columns Create motivational representations.

Such an optically variable surface pattern can be developed in the same way as the already described optically variable surface pattern. To avoid unnecessary repetition, reference is therefore made to the above statements.

The surface pattern according to the invention can be used as a master for the production of volume holograms. Furthermore, the optically variable surface pattern according to the invention can be used as a security element, in particular as a security element for a security paper, value document or the like. The security element can be designed as a security thread, tear-open thread, security strip, security strip, patch or as a label for application to a security paper, value document or the like.

The term security paper is to be understood here in particular as the precursor that can not yet be processed to form a value document which, in addition to the optically variable surface pattern according to the invention, also comprises further ones

Authenticity features (such as bulk luminescent materials). The term security paper includes not only papers, but e.g. also plastic or composite substrates, especially for banknotes. Value documents are here understood on the one hand as documents produced from security papers. On the other hand, value documents can also be other documents or objects which can be provided with the optically variable surface pattern according to the invention, so that the value documents have non-copyable authenticity features, whereby an authenticity check is possible and at the same time unwanted copying is prevented.

Furthermore, a value document having a surface pattern or further developments of the surface pattern according to the invention is provided.

The surface pattern according to the invention can also be used for purely decorative purposes. Furthermore, a method is provided for producing an optically variable area pattern (in particular of the optically variable area pattern according to the invention and its developments) in which a surface area is divided into pixels arranged in rows and columns, each pixel being associated with exactly one view of at least three viewing angle-dependent views is that in each row and / or in each column are pixels of at least two views, the position of a light-dark motif to be displayed in the area is set for each of the motive movement views upon tilting the fabricated area pattern about a first axis, wherein the motive movement comprises a movement along a first direction, which includes an angle of less than or equal to 30 ° with the first axis, and / or a rotation of the motive, for each fixed position the pixels of the corresponding view as a bright image determining the bright motif area, and the surface pattern is produced by forming the surface area with the bright pixels as reflective pixels on a carrier, so that when the surface pattern is tilted about the first axis, a viewer sees the at least three light-dark areas. Motivational representations can be perceived successively at different positions so that a motive movement is mediated, having the movement along the first direction and / or the rotation of the subject.

In particular, the assignment of each pixel to exactly one view of the at least three viewing-angle-dependent views can be carried out such that in each row and in each column pixels of at least two views are located.

Furthermore, a method for producing an optically variable area pattern (in particular of the optically variable areal invention) is provided. chenmuster and its developments), in which a surface area is divided into arranged in rows and columns pixels, each pixel is assigned to exactly one view of at least three viewing angle dependent views so that in each row and in each column pixels of at least two views are set, the position of a light-dark motif to be displayed in the area for each of the views for a motive movement with an orthoparallactic component, for each fixed position, the pixels of the corresponding view are determined as bright pixels to represent the bright subject area in that the surface pattern is produced by forming the surface area with the bright pixels as reflective pixels on a carrier, so that a viewer when tilting the manufactured surface pattern about a first axis, the at least three light-dark motif representations at different positions n can be perceived in succession so as to mediate a motive movement exhibiting the ortho-pacematory component.

The methods according to the invention can be developed in particular in such a way that they can be used to produce the optically variable area patterns according to the invention (including the developments of the optically variable area pattern). In particular, the manufacturing methods may include the steps described in connection with the description of embodiments of the optically variable area pattern. The assignment of the pixels to the views can in particular be such that pixels are located in each row and in each column of all views. It is understood that the features mentioned above and those yet to be explained below can be used not only in the specified combinations but also in other combinations or alone, without departing from the scope of the present invention.

The invention will be explained in more detail by way of example with reference to the accompanying drawings, which also disclose features essential to the invention. For better clarity, a scale and proportioned representation is omitted in the figures. Show it:

Figure 1 is a plan view of a banknote with an optically variable surface pattern according to the invention as a security element;

Figure 2 is an enlarged plan view of the surface pattern of Figure 1;

Figure 3 is a schematic view of the surface pattern of the invention;

Figure 4 is an enlarged schematic view of a pixel of the surface pattern;

Figure 5 is another view of a pixel of the surface pattern;

Figure 6 is a still further view of a pixel of the surface pattern;

FIGS. 7-10 show views of the surface area 13 with additionally marked position of the number "2" to be displayed; FIGS. 11-14 are views for explaining the position of the bright pixels for the different positions of the number "2" to be displayed according to FIGS. 7-10; FIG. 15 a representation of the surface area 13 with marked bright pixels of all four views;

Fig. 16 is a diagram for explaining the embodiment in which a two-dimensional ortho-parallax motion is presented;

Figures 17-20 representations of the surface area 13 according to an embodiment in which the surface area 13 is divided into two sections, in which opposing orthoparallakti- see movements are presented and

Figures 21-24 are views for explaining the position of the bright pixels for the different positions of the subject "L" to be displayed.

In the embodiment shown in FIG. 1, the optically variable surface pattern 10 according to the invention as a security element is integrated in a banknote 11 such that it is visible in the front side of the banknote 11 shown in FIG. Alternatively, the optically variable element 10 according to the invention can also be present as a window thread 12.

In the embodiment described here, the optically variable element 10 has a rectangular surface area 13 with a multiplicity of reflective pixels. As can be seen in particular from the enlarged schematic representation of the surface area 13 in FIG. 2, the surface area 13 has pixels 14 arranged in rows (direction R1) and in columns (direction R2), which are shown here schematically as squares. In each of the squares shown schematically, the number 1, 2, 3 or 4 is entered, which indicates an assignment of the pixels 14 to one of four representations presented, as will be described in more detail below. The different representations are to be recorded for a user depending on the viewing angle.

For the following description, the orientation of the optically variable element 10 shown in FIG. 3 to the coordinate system shown is assumed. The optically variable element 10 or the surface area 13 of the optically variable element 10 initially lies in the plane spanned by the x and y axes and can be rotated or tilted about the x axis and the y axis. the observer looking at the surface area 13 from the direction of the z-axis. For the viewer, an eye is represented schematically in FIG.

A rotation of the surface area 13 about the x-axis (change of the rotation angle a _x ) will be referred to as "north-south tilting" and rotation about the y-axis (change of the rotation angle a _y ) will be referred to as "east-west - tilting ".

In the embodiment described here, each pixel 14 is formed by a micromirror 15, wherein in FIG. 4 one of the micromirrors 15 is shown enlarged. The micromirror 15 has a mirror surface 16, which is the optically active surface of the micromirror 15 and whose orientation is determined by the specification of the surface normal vector n. Of the Surface normal vector n = {n _x , n _y , n ₂ ) should always be normalized to 1 and have a positive z-component. Under these conditions, the surface normal vector is already determined solely by the n _x and n _y components. The n _z component follows directly therefrom and is therefore not mentioned in the following. The edges Kl and K2 are in the xy plane.

In a first embodiment, the x component of the surface normal vector n of the micromirrors 15, as shown in FIG. 5 for a micromirror 15, can be zero and the n _y component of the micromirrors 15 can be varied. In the presence of a light source, the viewer can then align the optically variable element 10 so that it has the light source in the mirror reflex of some of the micromirrors 15. These micromirrors 15 then light up brightly, wherein according to the invention identically aligned micromirrors are arranged in the surface area 13 so that the entirety of the micromirrors, which light up brightly under a certain orientation of the optically variable element 10, presents the viewer with a pictorial representation, for example a symbol, a value number In the described embodiment, in the presence of the light source (preferably a point light source), the viewer may bring the micromirrors 15 with different orientations into the mirror reflex substantially by north-south tilting, ie, with such a surface pattern, the viewer will look down different tilt angles in north-south tilting respectively different representations or views of a subject. The visible motif is visible to the viewer as a light-dark representation.

The normalized normal vector n = (0, n _y , n _z ) in the described embodiment depends on the relationship n _y = sin β with the inclination angle β together, the mirror surfaces 16 of the micromirror 15 with the macroscopic surface (here in the xy plane) of the surface area 13 includes. For example, a value of n _y = 0.1 corresponds to an inclination angle of about 6 °. In order to switch between the mirror reflexes of two micromirrors 15 with n _y = 0 and n _y = 0.1 and to see the associated views, the area 13 must therefore be tilted in this case in the north-south direction by about 6 °.

In Figure 6 an embodiment is indicated, in which the n _y, in contrast to that described in connection with Figure 5 embodiment - component of all micro-mirror is 15 and the zero n _x component is varied. In this case, the micromirrors 15 illuminate at east-west tilt at different tilt angles.

Of course, in the general case, both the n _x and n _y components of the normal vectors of the mirror surfaces 16 of the micromirrors 15 may be nonzero.

An embodiment is described below in which the number "2" is generated as a light-dark motive with an orthoparallactic motion effect in north-south tilting so that the number "2" becomes visible at a total of four different horizontally displaced positions.

In Figure 7, the surface area 13 is shown in the same manner as in Figure 2, wherein now additionally the number "2" is drawn in its first position to be displayed by black squares. Here, the number "2" to be displayed has a pixel grid which corresponds to 2x2 pixels 14 of the area 13. For example, the pixel 17 covers the number to be displayed "2" four pixels 14. In FIGS. 8 to 10, further shift positions of the number "2" to be displayed are shown in the same way as in FIG.

The position of the number "2" shown in FIG. 7 should be visible as a view 1 in a first tilted position. Therefore, the pixels 14 of the first view (ie, the pixels 14 indicated by 1) covered by the pixels 17 of the number "2" to be displayed are oriented to light up at the first tilt position. This is shown in FIG. 11 by the drawn-in black circles.

In FIG. 12, the pixels 14 of the second view (ie the pixels 14, which are denoted by 2) are represented by a black circle, which are covered by the pixels 17 of the number "2" to be displayed, and by a second one

Kippstellung the position of the number "2" as a view 2 in accordance with Figure 8 represent. In FIGS. 13 and 14, the pixels 14 of the third and fourth views are then marked with black circles which correspond to the positions of the number "2" in FIG. 9 as view 3 or in FIG. 10 as view 4. In the light or dark appearing pixels 14, the micromirrors 15 can thus have the following orientations.

For a change between two views, the optically variable element 10 must be tilted by about 6 ° in north-south direction. If Carrying this out for all four views, the viewer is presented with the number "2" to be displayed at the various positions in succession so that it gives the impression that the number "2" is moving. This movement is orthoparallactic, ie the tilt about a horizontal axis in the illustrations according to FIGS. 11 to 14 leads to a movement along the tilting axis and not, as normally expected, perpendicular to the tilting axis.

For the moving representation of the number "2", the four views with four different positions in the surface area 13 are nested one inside the other. This is particularly clear from the representation in FIG. 15, in which the resulting tilt positions of the micromirrors 13 are represented in the present optically variable surface pattern 10. In this case, black circles show the bright pixels 14 of the first view, horizontally hatched circles the bright pixels 14 of the second view, white circles the bright pixels 14 of the third view and the circles with vertical hatching the bright pixels 14 of the fourth view. The remaining pixels have random orientations, so that the areas with these pixels do not appear as bright under any tilt angle as the bright motif representations of the different views. As can be clearly seen in the representation in FIG. 15, the interleaving of the different views results in bright pixels 14 being present for at least two different views in the rows in which micromirrors lie for bright pixels 14 of the views (line direction rl). In the same way, there are several columns, in each of which bright pixels 14 of different views are arranged.

The angular range under which bright pixels 14 and thus the corresponding micromirrors 13 are visible in mirror reflex depends in practice on several factors. A very extended light source leaves the micromirrors 13 appear to be longer bright when tilted out of the SLR than a point light source. At the same time, a not exactly flat mirror surface 15 of the micromirrors and / or (generally unwanted) diffraction effects can widen the reflected light beam by several degrees. In order to be able to see the associated representations separately, a certain difference in the orientations of the mirror surfaces 15 is therefore necessary. On the other hand, the representations for as liquid motion effects as possible are to merge into each other continuously, which is why the differences in the orientations of the mirror surfaces 15 belonging to different views must not be too great. Too large differences in orientation can lead to a "flickering" when tilting. A view is initially dark, before the next view lights up again bright. To achieve the most liquid motion effects without flicker, therefore, more than four views are preferably used in practice, for example ten views, which are then arranged with smaller orientation differences. To achieve a continuous movement effect, however, already three different views per tilt axis are sufficient. The more views per tilting axis are provided, the smoother the motion effects can be realized.

The random orientation of the dark pixels according to the above table prevents these areas from brightly illuminating at other angles. By random is meant here in particular that a pseudo-statistical distribution of the tilt angle for the inventive optically variable surface pattern is present. Different optically variable surface patterns may have the same pseudo-statistical distribution.

Alternatively, however, the micromirrors 13 may also have a predetermined orientation in the "dark" areas, so that the actually "dark" areas Areas then appear bright among other tilt angles. This can be realized, for example, by the following tilt angle distribution

In this case, you get the desired movement effect in north-south tilting, but this is combined with a contrast change in east-west tilting. Depending on the east-west tilt position, the actually "bright" or "dark" micromirrors light up brightly. Such a change in contrast can make the optically variable surface pattern 10 even more attractive. While such a contrast change in the representation of the number "2" described here can thus be quite attractive and desirable, a change in contrast may be undesirable in other subjects. For example, you do not want a portrait or a flag in the national colors to be tilted into the negative image. In this case, as already described, the tilt angles of the dark pixels may be selected at random.

Alternatively, there may be no micromirrors in the dark areas, but otherwise a dark coloration may be produced. This can be achieved, for example, via light-absorbing embossed structures, such as, for example, moth-eye structures, or a registered overprinting with a dark color. As a further alternative, it is also possible in these areas for light-scattering structures, for example diffractive matt structures or hollow microstructures. or micro-mirror, or there may be only a flat mirrored surface.

The assignment of the individual pixels 14 to the different views is illustrated here by the numbers 1, 2, 3 and 4 entered in the individual pixels 14, which, of course, are actually not present in the produced variable area pattern 10. It can also be said that in order to produce the optically variable area pattern, a surface area is divided into pixels arranged in rows and columns, and each pixel is precisely assigned to a view of at least three viewing angle-dependent views such that in each row and in each column are pixels of at least two views. Such a division of a surface area into pixels corresponds to e.g. In addition, the position of a light-dark motif to be displayed (such as the number "2" described in conjunction with FIGS. 7 to 15) is set in the area for each of the motions with an orthoparallactic component For each defined position, the pixels of the corresponding view are determined as bright pixels that are to represent the bright motif area. The surface pattern is then formed by forming the surface area with the bright ones

Pixels as reflective pixels produced on a support, as has already been described in detail, so that a viewer when tilting a surface pattern about a first axis, the at least three (here four) light-dark motif representations at different positions successively perceive so that a Motive movement is mediated, which has the ortho-parallactic component. In the production method, therefore, exactly the pixels are determined as bright pixels for each view, which should represent the bright motif area and then also formed as reflective pixels. The pixels of the view, not the bright subject area Although, as described, can also be designed as reflective pixels (eg with a random orientation), but can also be designed differently, for example as non-reflective surface sections and thus as non-reflective pixels. Thus, only a certain part of the pixels of a view is then formed as reflective pixels for the bright motif area on the carrier.

In the embodiments described so far, the micromirrors have been oriented in such a way that, in the case of north-south tilting, there is an orthoparallactic movement of the number "2" from left to right. It is also possible that the direction of movement of the motif does not coincide with the tilting axis (in the case of north-south tilting, this is the x-axis), but includes an angle which is preferably less than or equal to 30 °. In particular, the angle may be less than or equal to 10 °.

Alternatively, the different views can, of course, also show a value number "2" moving from top to bottom in east-west tilting. For this you can put, for example, n _y components of the orientations of the mirror surfaces 15 in bright areas to zero and the n _x - components of the mirror surfaces 15 of different views vary. Again, the micromirrors may be oriented so that there is an angle of less than or equal to 30 ° or less than or equal to 10 ° between the direction of movement and the tilt axis. It is also possible to realize a two-dimensional orthoparallactic movement, as indicated in FIG. 16. The double arrows PI show an east-west tilt and the double arrows P2 a north-south tilt. When north-south tilting takes place a change between the top left and bottom left in Figure 16 shown views 1 and 2 or between the right At the top and bottom right in Figure 16 shown views 3 and 4. In the east-west tilting takes place between the views 1 and 3 or between the views 2 and 4. To achieve this, the orientations of the mirror surfaces 15 of the bright Distinguishing image areas when displayed with horizontal offset in their n _y components and when displaying with vertical offset in their n _x components. A possible realization of the tilt positions would be as follows:

In practice, for such a representation for the purpose of the most fluid or continuous movement, of course, clearly more than a total of four different views can be used, for example, 5x5 = 25 or 10x10 = 100 different views could be nested here.

Instead of the randomly oriented micromirrors for the dark pixels, the already mentioned alternatives for dark areas can also be selected here. Thus, in the dark pixels, e.g. other fillings such as diffractive dark structures or dark inks may be present.

Another embodiment is shown in FIGS. 17 to 20. Here, the motif to be represented comprises two partial motifs, wherein in the upper half 18 of the surface region 13 in the north-south tilting a first value "1" runs from right to left and at the same time in the lower half 19 of the surface. chenbereiches a second value number "2" runs exactly opposite from left to right. Such opposing motion effects are particularly noticeable.

Instead of an exactly opposite movement, the individual motif components can also run in other different directions. For example, when tilted about the same axis, some of the numbers or symbols shown may move in opposite directions, and other numbers or symbols may, for example, move in mutually perpendicular directions of movement. The different views can also be designed in such a way that the motif components moving in different directions completely or partially overlap.

Of course, instead of the described exemplary motifs (numbers "1" and "2"), any other representations, such as symbols, may be represented.

In the embodiments described so far, the different views always show the same motif, which shows an orthoparallactic movement during tilting. However, it is also possible that the subject changes from one view to the next in addition to something else. For example, the subject may change abruptly or continuously into a different subject.

Furthermore, in addition to the ortho-parallactic movement for a first tilting direction, another effect may be provided for another tilting direction, for example, in the embodiment according to FIG. 16, the effect can be changed such that the view 1 and the view 2 instead of a "2", for example show the number "1". This would be the north-south tilting a Orthoparallaktische movement result and in the east-west tilting a flip between the value numbers "1" and "2".

In other embodiments, instead of a flip, another continuous kinematic effect may also be provided. For example, in North-South tilting, a wheel could perform right-to-left orthoparallactic motion and start rotating in east-west tilt.

The views can also be designed in such a way that, in addition to the ortho-parallax movement, there is an additional depth effect. Thus, for example a plurality of views with horizontally shifted designs, and different n _x components of the normal vectors as present in a stereogram and simultaneously according to horizontally offset views with different n _y components. In this way, a viewer sees the subject in front of or behind the plane of the surface area 13 and additionally observes an orthoparallactic movement during north-south tilting.

A depth effect can also be achieved by virtue of the fact that a left-to-right movement of the motif is not bound to a rotation exactly around the x-axis but, for example, about an axis of rotation which forms an angle with the x and y axes of 45 °. Also in this case, both north-south and east-west tilting lead to a left-to-right movement, the movement in the east-west tilting provides a stereographic depth impression and the movement during north-south tilting orthoparallaktische movement ,

FIGS. 21 to 24 show the positions of the bright pixels for different tilt angles in a north-south tilt for a motif "L" in the same way as in FIGS. 11 to 14, whereby a rotation of the motif "L" is shown here. is perceptible to the viewer. If the observer tilts the surface pattern in a north-south direction, he sees a rotation of the subject "L." Such a movement also has a striking dynamic, so that this movement effect is visually very memorable.Of course, such a rotation with the already described orthoparallaktischen movement or the substantially orthoparallaktischen movement are combined.

The optically variable element 10 according to the invention may e.g. be used as a security element, in particular as a security thread, security strip or patch. Such a security element can be molded in particular in a, for example, thermoplastic or radiation-curing paint, in particular on a carrier film. The micromirrors can be provided with a reflection-enhancing coating (Al metallization, thin-film interference coating, coating with liquid crystals, etc.). To protect against mechanical and / or chemical stress and to protect against unauthorized impression, the micromirror structures can be embedded in a protective lacquer.

The surface region 13 may be at least partially transparent and arranged over a transparent region of the substrate (in particular a banknote window).

The optically variable element 10 can also be used as a master for the exposure of volume holograms, which then likewise have the optical effects according to the invention.

Due to the comparatively simple construction of the optically variable element made of film / embossing lacquer / metallization, the optically variable element can be very thin. If the film has, for example, a thickness of 12 μιη and the embossing lacquer with the metallization has a thickness of, for example, less than 5 μm, there is a total thickness of less than 20 μm and in this case about 17 μm. Since the micromirrors are used, there is no need for registration between microstructures and lenses, as is the case with known moiré magnification arrangements.

Furthermore, the optically variable element 10 according to the invention can have a color-tilting functionality and can easily be combined with holograms and micro-mirror images with a convex effect, stereograms, etc. These can be embossed into the same embossing lacquer in one operation.

Furthermore, the optically variable element can be combined with other security features. For example, the optically variable element can be equipped with clear text (recesses in the form of a number, letter and / or character sequence in an opaque, in particular metallic coating), color tilting effects, magnet equipment, liquid crystals and / or fluorescence features.

The micromirrors 15 should be as small as possible for the lowest possible embossing depths and high resolution in many interlaced views. Preferred are dimensions of less than 100 μιτι, more preferably of less than 20 μπι or even less than 10 μπι. However, in order to obtain the desired radiation-optical mirror effect (specular reflection), the mirror surfaces 16 need a certain minimum size due to diffraction, which is preferably above about 3 μm and particularly preferably above about 5 μm. Each pixel 14 of the surface area 13 can either have only a single micromirror 15, or several micromirrors 15 can also be present. The micromirrors 15 may form a locally periodic sawtooth grid.

In the embodiment with locally periodic sawtooth gratings, the grating period can also be smaller than the above 3 μπι to 5 μιη. The mirror size in this case is the length at which the period of the sawtooth grid as well as its orientation and flank pitch remain approximately constant.

C onical list

10 Optically variable surface pattern

11 banknote

12 window thread

13 area area

14 pixels

15 micromirror

16 mirror surface

17 pixels

18 Upper half

19 Lower half

Rl row direction

R2 column direction

PI double-headed arrow

P2 double arrow

Claims

Patent claims

1. Optically variable surface pattern with

a carrier having a surface area with a plurality of reflective pixels arranged in rows and columns and oriented so that a viewer can perceive at least three light-dark motif representations at different positions one after the other as the surface pattern is tilted about a first axis in that a motive movement is imparted, which has a movement along a first direction, which forms an angle of less than or equal to 30 ° with the first axis, and / or a rotation of the motif,

wherein in at least one of the rows and / or in at least one of the columns lie pixels which generate the bright areas of at least two of the motif representations.

A surface pattern according to claim 1, wherein there are pixels in at least one of the rows as well as in at least one of the columns which generate the bright areas of at least two of the motif representations.

A surface pattern according to claim 1 or 2, wherein the first direction includes an angle with the first axis which is less than or equal to 10 °.

4. Surface pattern according to one of the above claims, wherein the bright areas are generated in each light-dark motif representation in each case by pixels each with the same aligned micro-mirrors.

5. Surface pattern according to one of the above claims, wherein the light-dark motif representations are two-dimensional motif representations. - 2 -

6. surface pattern according to one of the above claims, in which the light-dark motif representations each show the same motif.

7. surface pattern according to one of claims 1 to 5, wherein the light-dark motif representations show different motifs.

8. The surface pattern according to claim 1, wherein the dark areas of the light-dark motif representations are formed by reflective pixels having an orientation deviating from the reflective pixels of the bright areas.

9. The surface pattern according to claim 1, wherein the reflective pixels in the dark subregions are in each case oriented identically for all light and dark motif representations in such a way that, in another viewing or illumination situation, a viewer is viewing the negative representations of the respective light -Dark-style representation looks.

10. Surface pattern according to one of the above claims, wherein the dark portions of the light-dark motif representations by light-scattering structures, in particular diffractive matt structures, micro hollow or microroil mirror, light-absorbing embossed structures, in particular Mothaugenstrukturen, randomly oriented micromirrors, dark colored areas and / or specular reflecting areas are wholly or partially formed.

A surface pattern according to any one of the preceding claims, wherein in the case of east-west tilting, a stereographic depth effect is produced by a horizontal image shift and in a north-south tilt the movement along the first direction and / or the rotation.

12. surface pattern according to one of the above claims, wherein the surface area comprises two subregions in which the respective direction of movement and / or associated tilt axis of the light-dark motif representations are different.

13. surface pattern according to claim 12, wherein the two partial regions generate opposite directions of movement of the light-dark motif representations with the same tilting direction.

14. surface pattern according to claim 12, wherein the two subregions produce mutually perpendicular directions of movement of the light-dark motif representations in the same tilting direction.

15. Surface pattern according to one of claims 12 to 14, wherein the two subregions overlap at least partially.

16. surface pattern according to one of the above claims, wherein the dimensions of the micromirror between 2 μπι and 300 μπα, preferably between 3 μιη and 100 μιη and more preferably between 5 μι and 20 μπ are.

17. Use of a surface pattern according to one of the preceding claims as a master for the production of volume holograms.

18. Use of the optically variable surface pattern according to one of the above claims as a security element, in particular as a security element for security paper, value document or the like. - 4 -

19. Value document with an optically variable surface pattern according to one of claims 1 to 16.

20. A method for producing an optically variable area pattern in which

a surface area is divided into pixels arranged in rows and columns,

each pixel is assigned to exactly one view of at least three viewing angle-dependent views such that in each row and / or in each column are pixels of at least two views,

the position of a light-dark motif to be displayed in the area is set for each of the motive movement views upon tilting the fabricated area pattern about a first axis, the motive movement being a movement along a first direction and an angle with the first axis of less than or equal to 30 °, and / or has a rotation of the motif,

for each defined position, the pixels of the corresponding view are determined as bright pixels which are to represent the bright motif area,

and the surface pattern is made by forming the surface area with the bright pixels as reflective pixels on a support, so that a viewer can perceive the at least three light-dark motif representations at different positions one after the other, as the surface pattern is tilted about the first axis Motiv movement is mediated, which has the movement along the first direction and / or the rotation of the subject.