Optically variable display element

Abstract

The invention relates to an optically variable display element (12) having a reflective surface region (24) which, in reflected light, produces a three-dimensional display (14, 16) when viewed for at least two different viewing directions (44, 46), respectively, wherein the three-dimensional displays (14, 16) at least partially overlap and have different colors at least locally in the overlapping region. It is provided here that the reflective surface region (24) comprises a plurality of reflective facets (34, 36) in a first and a second partial region which at least partially overlap one another, respectively, which are oriented such that, for an observer viewing from a first viewing direction (44), the facets (34) of the first partial region produce a first three-dimensional display (14) having a surface which is protruding and / or recessed relative to its actual spatial shape, and, for an observer viewing from a second viewing direction (46), the facets (36) of the second partial region produce a second three-dimensional display (16) having a surface which is protruding and / or recessed relative to its actual spatial shape. The facets (34, 36) of the reflective surface region (24) are at least locally provided in the overlapping region of the first and second partial region with a sub-wavelength structure (38) which produces the different colors of the three-dimensional displays (14, 16).

Description

Technical Field

[0001] The present invention relates to an optically variable display element having a reflective surface area, which can be used as a security element for protecting valuables or as a decorative element, for example, for the surface design of a product. Background Technology

[0002] Data carriers, such as valuable documents or identification cards, and other valuables, such as brand-name items, are typically equipped with security elements for protection. These security elements allow verification of the data carrier's authenticity and also serve as protection against unauthorized copying. Security elements with viewing angle-dependent or three-dimensional appearance play a special role in authenticity protection because they cannot be copied even using the most modern photocopiers. For this purpose, security elements are equipped with optically variable elements that convey different image impressions to the observer at different viewing angles, such as displaying different color impressions, brightness impressions, and / or different graphic patterns depending on the viewing angle.

[0003] Here, in the prior art, effects such as motion, pumping, depth or flipping are described as optically variable effects, which are achieved by means of holograms, microlenses or micromirrors.

[0004] For example, it is known from document WO 2014 / 060089 A2 that a convex effect dependent on the viewing angle can be produced using a micromirror. More recently, a more complex, optically variable safety element has been proposed, featuring two undulating structures arranged at different height levels, each with a colored coating (see WO 2020 / 011390A1, WO 2020 / 011391 A1, and WO 2020 / 011391 A2). Here, the colored coating of the higher-positioned undulating structure is constructed as a grid or has grooves, such that when the safety element is observed, the colored coating of the lower-positioned undulating structure appears in the grid gaps or grooves. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to provide an optically variable display element with an attractive visual appearance, which can be manufactured at low cost and also ideally has high anti-counterfeiting security.

[0006] The aforementioned technical problems are solved by the features of the independent claims. The improvements of the present invention are the subject of the dependent claims.

[0007] To address the aforementioned technical problem, the present invention includes an optically variable display element having at least one reflective surface region that, when viewed with reflected light, produces a three-dimensional display for at least two different viewing directions. The three-dimensional displays at least partially overlap and at least locally exhibit different colors in the overlapping regions.

[0008] For this purpose, at least one reflective surface region includes a plurality of reflective facets in a first portion region and a second portion region that at least partially overlap with each other. The reflective facets are oriented such that, on the one hand, for an observer viewing from a first viewing direction, the facets in the first portion region produce a first three-dimensional display having surfaces that protrude and / or recede relative to their actual spatial shape; on the other hand, for an observer viewing from a second viewing direction, the facets in the second portion region produce a second three-dimensional display having surfaces that protrude and / or recede relative to their actual spatial shape.

[0009] The appearance produced by the observer as a prominent and / or retracted surface is understood here in particular as a portion of the surface being perceived as a continuously arched surface.

[0010] Here, the appearance of an arched display in the current sense is mimicked by adjusting the reflective properties of the arched surface. This indirectly creates an impression of depth or 3D. Therefore, this impression can also be referred to as a "2.5" dimensional display or an undulating display.

[0011] Here, the small planes of the reflective surface region are provided with subwavelength structures at least locally in the overlapping area of ​​the first and second part regions, and the subwavelength structures produce different colors in the three-dimensional display.

[0012] In an advantageous design, the facet of the reflective surface region is provided with a reflection-enhancing coating, particularly a metallization, a high-refractive-index layer, and / or a thin-layer structure. Here, the reflection-enhancing coating is provided not only in the first portion of the facet but also in the second portion. The metallization can be formed, for example, from Al, Ag, Cr, Cu, Fe, or alloys of these metals. A ZnS layer can be provided as the high-refractive-index layer, for example. As the thin-layer structure, color-shifting systems with an absorber / dielectric / reflector structure or a symmetrically translucent absorber / dielectric / absorber structure are particularly considered.

[0013] The facets of the reflective surface region are advantageously formed in the embossed coating layer, particularly in thermoplastic or radiation-cured embossed coating layers. It is particularly advantageous to use UV-cured embossed coating layers. The arrangement of facets, including subwavelength structures, is embossed into the embossed coating layer, and the embossed structure is preferably coated with the reflective enhancement coating. The embossed, and preferably coated, embossed structure is advantageously embedded in another coating layer, such as a protective coating layer.

[0014] Particularly preferably, the small plane of the reflective surface region is formed by a micromirror device with directional reflective micromirrors, particularly by micromirrors having linear dimensions between 3 μm and 100 μm, preferably between 5 μm and 50 μm. The micromirrors can, in particular, have triangular, square, rectangular, hexagonal, or other polygonal base surfaces. The pitch of the micromirrors is advantageously less than 15 μm, preferably less than 10 μm.

[0015] Subwavelength structures are advantageously formed from periodic structures with period lengths between 100 nm and 500 nm, preferably between 200 nm and 400 nm, and / or depths between 50 nm and 400 nm, preferably between 100 nm and 300 nm. The aspect ratio of such structures, i.e., the ratio between the width of the bulge or depression and the corresponding structural depth, can advantageously be between 1 / 4 and 4, preferably between 1 / 3 and 3, and particularly preferably between 1 / 2 and 2.

[0016] In order to produce particularly clear and pure colors, the period length of the subwavelength structure and the linear size of the micromirror are preferably coordinated with each other, such that at least 10, preferably at least 20, complete periods of the subwavelength structure are accommodated on each micromirror.

[0017] In addition to periodic structures, aperiodic structures can also be used, wherein the average center-to-center distance of the subwavelength structure is advantageously between 100 and 500 nm, preferably between 200 and 400 nm.

[0018] In one advantageous design, the subwavelength structure is formed using a one-dimensional grating, which can also have a polarizing effect. In another equally advantageous design, the subwavelength structure is formed using a two-dimensional grating, particularly a two-dimensional grating with rectangular, square, hexagonal, or parallelogram grating symmetry. The subwavelength structure can be formed, in particular, using intersecting sinusoidal gratings, intersecting rectangular gratings, hexagonal grating structures, or using nanodot arrays or nanopore arrays.

[0019] As for the profile shape, sinusoidal gratings, rectangular gratings (binary structures) are particularly considered for subwavelength structures, or profile shapes with concave and / or convex segments are also considered. Periodic arrangements of nanopores or nanodots with arbitrary border shapes can also be used. In addition to regular arrangements, irregular arrangements can also be used, such as those that are randomly distributed or quasi-periodic, and can be characterized by parameters such as border shape, depth, and profile shape (e.g., binary or other shapes with concave and / or convex segments). In principle, structures as described in documents EP 3 367140A1 and EP 3 401 712 A1 are also possible, and their disclosures are incorporated herein by reference.

[0020] In the reflective surface region, especially in the overlapping region, at least two different subwavelength structures are advantageously provided to produce different colors, the subwavelength structures being particularly different in terms of their period length and / or their depth and / or their profile shape (e.g., by different ratios of patch width and groove width).

[0021] Advantageously, the subwavelength structures of different colors used for 3D display are arranged in registration with the facets of the reflective surface region, such that each facet is covered only by a specific type of subwavelength structure. However, it is also possible in principle that the color boundaries extend independently of the facet division of the surface region, allowing facets with different subwavelength structures to exist.

[0022] In a preferred design, the colors visible to an observer when viewing the display element are generated using specific types of subwavelength structures, which are characteristic of those colors. Alternatively, the colors visible to an observer when viewing the display element may also include mixed colors, generated by color mixing of pixel-like sub-regions having sizes below the resolution limit of the human eye. The colors of these pixel-like sub-regions are generated using specific types of subwavelength structures, which are characteristic of those colors. Here, the sub-regions preferably have a size of less than 150 μm, particularly less than 100 μm.

[0023] Here, pixel-like regions or "pixels" do not necessarily exist as rectangular or square regions on right-angled grids, but can also represent sub-regions of different shapes, such as those derived from mosaic-like surfaces.

[0024] In an advantageous design, in the overlapping region, not only the facets of the first region but also the facets of the second region are at least locally provided with subwavelength structures, which produce different colors in the three-dimensional display. Alternatively, one of the different colors can also be formed by the color of the coating on the facets without the involvement of the subwavelength structures, particularly by the color of the silver, gold, bronze, or copper-colored metallized portions, the color of the high-refractive-index layer appearing white or colored, or the color of the multilayer interference coating. White and the metallic color of the metallic coating are also colors within the scope of this specification. However, at least one of the different colors in the three-dimensional display is always produced by the subwavelength structures of the facets.

[0025] In an advantageous design, the three-dimensional display has different shapes and / or sizes, allowing the observer to perceive different spatial patterns from at least two different viewing directions.

[0026] In another equally advantageous design, the three-dimensional displays have the same shape and size and are arranged in an overlapping manner, such that the three-dimensional displays can be distinguished from at least two different viewing directions only by at least locally different colors.

[0027] To overlap certain regions, the first and second regions are advantageously nested within each other. For this purpose, the regions are preferably formed by narrow, alternating strips arranged side-by-side or by small sub-regions nested within each other in two dimensions. Here, the strips or sub-regions advantageously have a size of less than 300 μm, particularly 100 μm or smaller, particularly 50 μm or smaller, in at least one direction. For example, square sub-regions with a size of 100 μm × 100 μm can be nested within each other in a checkerboard pattern, where the "white checkerboard" represents a sub-region of the first region and the "black checkerboard" represents a sub-region of the second region. The sub-regions can also have complex border shapes and form small pieces that resemble tiles in a plane.

[0028] It should be understood that the strips or sub-regions of the first and second regions typically comprise multiple facets of the relevant sub-region. For example, a square sub-region with dimensions of 100 μm × 100 μm comprises 100 facets or micromirrors with a base of 10 μm × 10 μm. However, in extreme cases, each sub-region may also consist of only a single facet or a single micromirror.

[0029] Preferably, the display element comprises exactly two views for two different viewing directions. With only two views, both views can appear very bright and clearly distinguishable. However, designs with three, four, or more views for a corresponding number of viewing directions are also possible, in which the brightness of each view decreases with the increase in the number of views, and the viewing directions are closer to each other.

[0030] It has been proven advantageous to choose colors for three-dimensional displays in a way that makes them easy for the observer to remember or directly understand, such as a theme of roses with red flowers and green stems. Other examples include patterns of blue water droplets, gold stars, white snowflakes, red, yellow, and green traffic lights, and red hearts or green clover patterns.

[0031] Display elements are advantageously used as security elements to protect valuable items, particularly security threads, tear lines, seat belts, security strips, patches, or labels applied to security paper, valuable documents, etc.

[0032] Display elements can also be used as decorative elements for the surface design of products, such as for the interior space design of motor vehicles or for the surface design of electrical equipment or furniture.

[0033] The invention also includes a data carrier comprising a display element of the type described above as a security element. The data carrier can be, in particular, a valuable document, such as banknotes, especially paper banknotes, polymer banknotes, or film composite banknotes; it can be stocks, bonds, certificates, vouchers, checks, seals, tax tags, high-value admission tickets, but can also be an identification card, such as a credit card, bank card, cash payment card, authorization card, ID card, or personalized page of a passport. Attached Figure Description

[0034] Other embodiments and advantages of the invention are described below with reference to the accompanying drawings. For clarity, the drawings are not reproduced to scale.

[0035] In the attached image:

[0036] Figure 1 A schematic diagram of a banknote having an optically variable security element according to the present invention is shown.

[0037] Figure 2 Schematic illustration in cross-section Figure 1 The structure of safety components,

[0038] Figure 3 Schematic illustrations are shown in (a) and (b). Figure 1 The curves of the modulated height function of the safety element in two views are shown in (c), and the entire structured curve after the nested modulated height function is schematically shown to illustrate the more precise construction and manufacture of the safety element.

[0039] Figure 4 First and second views of a safety element according to another embodiment of the present invention are shown.

[0040] Figure 5 First and second views of a safety element according to another embodiment of the present invention are shown, and

[0041] Figure 6 First and second views of a safety element according to another embodiment of the present invention are shown, wherein the two three-dimensional patterns shown are identical in shape and size. Detailed Implementation

[0042] The invention will now be described using a security element for banknotes as an example. Therefore, Figure 1A schematic diagram of a banknote 10 with an optically variable security element 12, which is in the form of an adhesive transfer element, is shown. However, it should be understood that the invention is not limited to transfer elements and banknotes, but can be used for all types of security elements, such as labels for goods and packaging, or for protecting documents, ID cards, passports, credit cards, health cards, etc. In the case of banknotes and similar documents, in addition to transfer elements (such as patches or strips with or without their own carrier layer), security threads or security strips, for example, can also be considered. Besides being used as security elements, the display element according to the invention can also be used as a decorative element, for example, in the surface design of electrical equipment.

[0043] Reference Figure 1 The security element 12 applied to the banknote 10 is itself constructed to be very flat, yet still presents a three-dimensional view to the observer from at least two different viewing directions 44, 46, creating the impression of a pattern that clearly protrudes from the plane of the banknote 10. Here, the reflective properties of the raised pattern are reproduced through directional reflection. These two three-dimensional displays overlap each other and are at least locally different colors, resulting in a visually striking flipping effect when the viewing direction is changed, where the color and pattern of the three-dimensional display change simultaneously at the same location within the security element 12.

[0044] Specifically, for example, when viewed from the left, as a first view 50, the security element 12 can display a blue three-dimensional raised value 14 ("50") against a flat blue background. And when viewed from the right, as a second view 52, ​​it shows a yellow three-dimensional raised star 16 against a flat yellow background. When the viewing direction is changed or when the banknote 10 is tilted from left to right 18, the appearance of the security element 12 changes between the first view with the three-dimensional blue value 14 and the second view with the three-dimensional yellow star 16. Furthermore, the two three-dimensional patterns 14, 16 appear to the observer to overlap each other at the same location in the security element 12, as indicated by the borders 14', 16' drawn with dashed lines of the corresponding additional patterns in each view 50, 52.

[0045] Therefore, the security element 12 exhibits a tilting characteristic, where two different colored patterns are visible to the observer from the same position in two viewing directions, and the pattern change is correlated with a simultaneous color change when tilted. This tilting effect is visually appealing and easy for users to remember. It also provides high anti-counterfeiting protection because the reproduction effect of a reflective embossed structure, for example, by overprinting with transparent colors, is practically impossible to achieve with conventional printing presses due to the registration stability required between the reflective elements and associated colors in different pattern views.

[0046] As described below regarding the structure of the safety element according to the invention, only one embossing and one metallization are required, and no additional color layer is needed. Compared to known designs with two embossings and two metallizations or color coatings, the safety element can be manufactured with significant cost advantages because the number of material layers and processes used can be significantly reduced during manufacturing.

[0047] Figure 2 The structure of the safety element 12 is schematically shown in cross-section. An imprinted enamel layer 22 is applied to the carrier substrate 20, and an undulating structure in the form of a micromirror device 26 is imprinted into this enamel layer in the surface region 24. The micromirror device 26 has a reflection-enhancing coating in the form of a metallization, for example, a 50 nm thick aluminum layer. For clarity, this aluminum layer... Figure 2 Not shown in the image.

[0048] As detailed below, the micromirror device 26 comprises two sets of micromirrors 34 and 36, which are tilted relative to the plane of the surface region 24, such that they mimic the reflective properties of views 50 and 52 with three-dimensional pattern values ​​14 and 16 from two viewing directions for the observer 40. Here, each micromirror 34 and 36 has a linear dimension l between 5 μm and 50 μm. M And therefore, for example, it has a square base of 10μm × 10μm, and is therefore indistinguishable to the observer.

[0049] The different color effects of views 50 and 52 with patterns 14 and 16 are produced by superimposing micromirror device 26 with different subwavelength structures 38, as shown in Figure 2 As shown in detail section 30, the color produced in reflection by the subwavelength structure 38 can be adjusted by selecting structural parameters, particularly the grating period and the structure depth. The grating period of the subwavelength structure is between 200 nm and 400 nm and is therefore below the wavelength of visible light, and the structure depth is between 50 nm and 400 nm.

[0050] By modulating a micromirror device with a subwavelength structure, the undulating structure 26 can be divided into multiple micromirrors 34 and 36 as a coarse structure of the undulating structure 26, and the modulation of micromirrors 34 and 36 with a subwavelength structure 38 can be regarded as a fine structure of the undulating structure 26.

[0051] refer to Figure 3 The manufacturing of safety element 12 may be carried out, for example, as follows, wherein, for further details of the coarse structure, reference WO 2014 / 060089 A2, the disclosure of which is incorporated herein by reference.

[0052] First, the views containing the three-dimensional patterns 14 and 16 to be displayed are characterized by height functions h(x, y) based on their position coordinates x and y in the plane. From these height functions, reduced height functions are derived, each having the same local slope as its parent height function, but not exceeding a preset maximum height h. max These reduced height functions describe the profile of the micromirror device, which mimics the reflective properties of the pattern 14 or 16 to be displayed. The reduced height functions have a stepped profile with a maximum step height h. max And it has a stepped dimension l in the plane of the surface region. M The size of this step corresponds to the size of the subsequently generated micromirrors 34 and 36. For example, the step size of the reduced height function is 10 μm × 10 μm, and the maximum step height is 10 μm.

[0053] Then, the local slopes of the two reduced height functions are rescaled and offsets are set respectively, so that the scaled height functions describe the contours of the micromirror device, which readjusts the reflective properties of the patterns 14 and 16 to be displayed from one of two different viewing directions 44 and 46. For example, in the case of perpendicular light incidence, the first view 50 with the first three-dimensional pattern 14 can appear at an angle of approximately -53° (viewing direction 44), and the second view 52 with the second three-dimensional pattern 16 can appear at an angle of approximately +53° (viewing direction 46). By rescaling the local slopes, it is ensured that the absolute value of the maximum slope, despite the additive offsets, does not exceed a preset maximum value. Because the step size l M The height of the steps remains limited as it is not changed by rescaling.

[0054] For the desired color effect, the scaled height function is superimposed on a grating function describing the undulation curve of a subwavelength grating g1 or g2, respectively, thereby obtaining a modulated height function m1(x, y) or m2(x, y). Specifically, for example, the scaled height function of the first view 50 is modulated using a subwavelength grating function g1, which is designed to produce a blue reflective color, and the scaled height function of the second view 52 is modulated using a subwavelength grating function g2, which is designed to produce a yellow reflective color. The grating constants of the two subwavelength gratings g1 and g2 are between 200 nm and 400 nm, thus allowing for modulation of the height function in each micromirror (step size l). M Subwavelength structures with 25 to 50 complete cycles can be accommodated on a surface of 10 μm. Therefore, the subwavelength structures produce very clear and pure colors.

[0055] To illustrate, Figure 3In (a) and (b), the curves of the modulated height function m1(x,y) of the first view 50 with the first pattern 14 and the curves of the modulated height function m2(x,y) of the second view 52 with the second pattern 16 are schematically shown, along with inclined viewing directions 44 and 46 from which the corresponding views are displayed for the observer 40. The modulation of the micromirror device with subwavelength gratings g1 or g2 is shown only in detail view 30, while the rough curves of the stepped profiles of the scaled height functions are visible in the undulating curves shown without magnification.

[0056] Then, according to Figure 3 The two modulated height functions in (a) and (b) are nested, for example in a checkerboard pattern, to generate a common structured r(x, y) for the contour of the undulating structure 26. The common structured r(x, y) is the contour of the nested, modulated micromirror device, showing a first view 50 of a first three-dimensional pattern 14 with a first color from a first viewing direction 44, and a second view 52 of a second three-dimensional pattern 16 with a second color from a second viewing direction 46. The curve of the structured r(x, y) is... Figure 3 As shown in (c), where, Figure 3 (b) Vertical arrows 64 and 66 indicate which regions of the undulating structure 26 originate from the first modulated height function m1(x,y) of the first view 50 (arrow 64) and which regions originate from the second modulated height function m2(x,y) of the second view 52 (arrow 66).

[0057] As already shown, human perception is designed to identify slope variations within patterns 14, 16 based on curvature or arching, while the absolute value of the slope, i.e., the tilt produced by the added offset of the two patterns 14, 16, is less noticeable. If the structured r(x, y) is thus imprinted into the imprinted paint layer and provided with a reflective enhancement coating, the resulting undulating structure 26 shows a first view 50 with the first pattern 14 in blue from the first viewing direction 44, and a second view 52 with the second pattern 16 in yellow from the second viewing direction 46.

[0058] As a subwavelength structure, a perforated grating with a period and depth of approximately 250 nm can be used, which has a metallized portion, for example, in the form of an aluminum layer approximately 50 nm thick. To produce different colors, the grating period, grating depth, and the size of the individual holes (e.g., square or circular holes) can be varied.

[0059] Reference Figures 4 to 6Not only can the colors of the first and second views be different as a whole, but the arched patterns and / or flat backgrounds within a single view can also be constructed in different colors or even in multiple colors separately. One of the two arched patterns or the flat background can also be formed without a subwavelength structure and then appear together with the usual metallic color of the reflective enhancement coating.

[0060] refer to Figure 4 For example, the first view 70 may show an arched blue number 72 against a green background 74, and the second view 80 may show an arched yellow star 82 against a red background 84. The appearance changes between the first view 70 and the second view 80 when the safety element is tilted 18.

[0061] Within a 3D pattern, two arched elements of different colors can also be visible. For example, in the arched pattern of the first view, the value "50" can be composed of a blue number "5" and a red number "0". It can also be specified that the color changes within the arched elements.

[0062] For example, in Figure 5 The first view 90 shown includes a red value 92 with a central blue stripe 94 and a flat red background 96, wherein the colors of these areas are generated by subwavelength structures of the type described above. Figure 5 In the second view 100, the micromirrors are not modulated with a subwavelength structure, causing the arched star 102 and the flat background 104 to appear in the bright silver metallic color of the metallized portion of the micromirror device. In this design, the appearance of the safety element changes between a first view with three-dimensional red / blue values ​​92 and 94 against a red background and a second view with a three-dimensional metallic star 102 against a metallic background. Structurally, after nesting the micromirrors of two views 90 and 100 in the overlapping area, only the micromirrors in the first view have a subwavelength structure, while the micromirrors in the second view are not modulated by a subwavelength structure.

[0063] Advantageously, it can also be specified that the two displayed three-dimensional patterns are identical in shape and size, and that the patterns differ only in their colors. For example, Figure 6The safety element includes a first view 110 and a second view 120. The first view 110 has a red, arched numerical value 112 against a flat, metallic background 114, and the second view 120 has a green, arched numerical value 122 against a flat, metallic background 124. Here, the micromirrors of the safety element are provided with subwavelength structures for the desired red or green color in the regions of the arched numerical values ​​112 and 122, respectively, while the background regions 114 and 124 are respectively configured as unmodulated subwavelength structures. Therefore, when the safety element is tilted, an observer sees the arched numerical value "50," which is visible in red when viewed from the left and in green when viewed from the right, respectively, against the silver metallic background of the aluminum coating of the micromirror device.

[0064] In the case of a three-dimensional pattern of the same shape, when tilted by 18 degrees, the color can also advantageously change only in a portion of the pattern, and thus highlight that portion of the pattern.

[0065] Another design approach is to generate color variations through continuous changes in the parameters of the subwavelength structure, particularly its period and / or depth. For example, an arched pattern could have a color change from red to green from top to bottom.

[0066] Similarly, a design scheme can be conceived in which the flipping effect appears locally under different flipping angles and / or flipping axes. Thus, for example, in the first surface region, there may be an angle-dependent arching effect with color changes and possible pattern changes when tilted north / south, and in the second surface region, another angle-dependent arching effect with color changes and possible pattern changes may appear when tilted east / west.

[0067] In the alternative design, the tilt axis can be the same in different surface areas, but the tilt angles are different, which can achieve a motion effect. Therefore, for example, when tilting around a preset axis, multiple first arched patterns, such as three yellow arched stars, can successively transform into multiple second arched patterns of different colors, such as three red arched letters or numbers.

[0068] List of reference numerals

[0069] 10 banknotes

[0070] 12 Safety Components

[0071] 14, 14' numerical patterns

[0072] 16' Star Pattern

[0073] 18. Inclined

[0074] 20 Support substrate

[0075] 22 Embossing paint layer

[0076] 24-sided area

[0077] 26 Micromirror apparatus

[0078] 30 Details

[0079] 34 and 36 microscopes

[0080] 38 Subwavelength Structure

[0081] 40 Observers

[0082] 44, 46 Observation direction

[0083] Views 50 and 52

[0084] Arrows 64 and 66 used for area display

[0085] 70 Views

[0086] 72 Blue numerical pattern

[0087] 74 Green Background

[0088] 80 Views

[0089] 82 Yellow star pattern

[0090] 84 Red background

[0091] 90 Views

[0092] 92 (Red Value)

[0093] 94. Blue stripe in the middle

[0094] 96 Red background

[0095] 100 Views

[0096] 102 Star Pattern

[0097] 104 Background

[0098] 110 First View

[0099] 112 Red numerical pattern

[0100] 114 Metal Background

[0101] 110 Second View

[0102] 122 Green numerical pattern

[0103] 124 Metal Background

Claims

1. An optically variable display element having at least one reflective surface region, said reflective surface region generating a three-dimensional display when viewed in reflected light from at least two different viewing directions, wherein, The three-dimensional displays at least partially overlap and have at least locally different colors in the overlapping regions, wherein, - The at least one reflective surface region includes a plurality of reflective facets in first and second portion regions that at least partially overlap each other, the reflective facets being oriented such that -- For an observer viewing from a first viewing direction, the small planes of the first partial region produce a first three-dimensional display with surfaces that protrude and / or recede relative to their actual spatial shape, and -- For an observer viewing from a second viewing direction, the small planes in the second portion of the region produce a second three-dimensional display with surfaces that protrude and / or recede relative to their actual spatial shape, and - The small planes in the reflective surface region have at least locally localized subwavelength structures in the overlapping area of ​​the first and second partial regions, the subwavelength structures producing different colors in the three-dimensional display. The feature is that the small plane of the reflective surface region is formed by a micromirror device with micromirrors having directional reflection, wherein the subwavelength structure is formed by a periodic structure, and the period length of the subwavelength structure and the linear size of the micromirror are coordinated with each other, so as to accommodate at least 10 complete periods of the subwavelength structure on each micromirror.

2. The display element according to claim 1, characterized in that, The small planes of the reflective surface area are provided with a reflection-enhancing coating.

3. The display element according to claim 2, characterized in that, The reflection-enhancing coating is a metallized part, a high refractive index layer, and / or a thin-layer structure.

4. The display element according to any one of claims 1 to 3, characterized in that, The planar structure of the reflective surface region is within the embossed paint layer.

5. The display element according to claim 4, characterized in that, The embossed paint layer is a thermoplastic or radiation-cured embossed paint layer.

6. The display element according to any one of claims 1 to 3, characterized in that, The small planes of the reflective surface region are formed by micromirrors having linear dimensions between 3 μm and 100 μm.

7. The display element according to any one of claims 1 to 3, characterized in that, Each micromirror contains at least 20 complete cycles of a subwavelength structure.

8. The display element according to any one of claims 1 to 3, characterized in that, The subwavelength structure is formed by a periodic structure with a depth between 100 nm and 500 nm.

9. The display element according to any one of claims 1 to 3, characterized in that, The subwavelength structure is formed by a one-dimensional grating or a two-dimensional grating.

10. The display element according to claim 9, characterized in that, The two-dimensional grating is a two-dimensional grating with rectangular, square, hexagonal, or parallelogram grating symmetry.

11. The display element according to any one of claims 1 to 3, characterized in that, At least two subwavelength structures are provided to produce different colors, the subwavelength structures being different in their period length and / or their depth and / or their contour shape.

12. The display element according to any one of claims 1 to 3, characterized in that, Subwavelength structures of different colors used for 3D display are registered with facets of the reflective surface region, such that each facet is covered only by a specific type of subwavelength structure.

13. The display element according to any one of claims 1 to 3, characterized in that, When observing a display element, the colors visible to the observer are generated by specific types of subwavelength structures, which are characteristic of the colors.

14. The display element according to any one of claims 1 to 3, characterized in that, When observing a display element, the colors visible to the observer include mixed colors, which are generated by color mixing of colors from pixel-like sub-regions with sizes below the resolution limit of the human eye, and wherein the colors of the pixel-like sub-regions are generated by specific types of subwavelength structures that are characteristic of the colors.

15. The display element according to any one of claims 1 to 3, characterized in that, In the overlapping region, not only the small planes of the first part of the region but also the small planes of the second part of the region are provided with subwavelength structures at least locally, and the subwavelength structures produce different colors for three-dimensional display.

16. The display element according to any one of claims 1 to 3, characterized in that, One of the different colors is also formed by the coating of small facets, without the involvement of subwavelength structures.

17. The display element according to claim 16, characterized in that, The color of the coating on the facet is silver, gold, bronze, or the color of the copper-colored metallized portion, appearing as a white or colored high-refractive-index layer, or the color of a colored multilayer interference coating.

18. The display element according to any one of claims 1 to 3, characterized in that, The three-dimensional display has different shapes and / or sizes.

19. The display element according to any one of claims 1 to 3, characterized in that, The three-dimensional displays have the same shape and size and are arranged in an overlapping manner, such that the three-dimensional displays can be distinguished from the at least two different viewing directions only by at least locally different colors.

20. The display element according to any one of claims 1 to 3, characterized in that, The first and second regions are nested within each other, wherein the first and second regions are formed by narrow, alternating side-by-side strips or by small, nested sub-regions in two dimensions.

21. The display element according to any one of claims 1 to 3, characterized in that, The display element is a security element used to protect valuable items.

22. A data carrier having an optically variable display element according to any one of claims 1 to 20.

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