TW201344588A - Optically variable security element - Google Patents

Abstract

The present invention relates to an optically variable security element (12) for security papers, value documents and other data carriers, having a substantially transparent substrate (20) having opposing first and second main surfaces (22, 24), an arrangement composed of microlenses (26) arranged on the first main surface (22) of the substrate, arranged on the second main surface (24) of the substrate, a laser-sensitive recording layer (30) that includes stacked first and second sub-layers (32, 34), the first sub-layer (32) being arranged between the substrate (20) and the second sub-layer (34), a plurality of microholes (40) produced in the laser-sensitive recording layer by the action of laser radiation, of which each microhole (40) is associated with a microlens (26) and is visible when the security element is viewed through the associated microlens (26) from a certain viewing angle, the plurality of microholes comprising a plurality of first and a plurality of second microholes (42, 44), the first microholes (42) being present in the first sub-layer (32) and not going through the recording layer (30), and the second microholes (44) going through the recording layer (30) with the first and second sub-layer (32, 34), and the diameter of the first microholes (42) being larger than the diameter of the second microholes (44).

Description

Optically variable safety element

The present invention relates to optically variable security elements for security papers, value documents and other data carriers; methods for making such security elements; and data carriers having such security elements.

For protection purposes, data carriers (such as value or identification documents, but also other valuable items, such as branded items) are often provided with security elements that allow verification of the authenticity of the data carrier while As a protection against unauthorized reproduction.

Safety elements with a view-dependent effect play a special role in maintaining authenticity, because even with the most modern copying machines, these safety elements cannot be reproduced. Here, the security element is provided with an optically variable element viewed from a different viewing angle, conveying a different image impression to the viewer and displaying, for example, another color or brightness impression and/or another pattern depending on the viewing angle.

For example, identification cards (such as credit cards or personal identification cards) have long been personalized by laser engraving. In the personalization by laser engraving, the optical properties of the substrate material are irreversibly altered in the form of the desired mark by appropriately guiding the laser beam. This laser marking makes it possible to combine the personalization of the data carrier with the security element and can be compared to existing ones. Personalized methods, such as the well-known numbering method, are more free to integrate laser markers into printed images.

Document EP 0 219 012 A1 describes an identification card having a partial lens grid pattern. Through this lens pattern, a piece of information is engraved in the card at different angles using a laser. Subsequently, these pieces of information can only be perceived at this angle, so that different pieces of information appear when the card is tilted.

From this point of view, the object of the invention is to specify a security element of the above kind which has an attractive visual appearance and high security against forgery.

This object is solved by the features of the scope of the patent application of the independent item. The development of the present invention is the subject matter of the patent application scope of the subsidiary.

According to the present invention, a general security element comprises: a substantially transparent substrate having opposing first and second major surfaces; an arrangement of microlenses disposed on the substrate a laser sensitive recording layer disposed on the second major surface of the substrate, the laser sensitive recording layer comprising stacked first and second sublayers, the first sublayer being disposed on the Between the substrate and the second sub-layer; a plurality of micro-holes formed in the laser-sensitive recording layer by the action of laser radiation, wherein each micro-hole is associated with a microlens, and when viewed from a viewing angle The security element may be visible through the associated microlens; the plurality of microholes comprise a plurality of first microwells and a plurality of second microwells, the first microwells being present in the first sublayer And not penetrating the recording layer, and the second microhole penetrates the recording layer The first and second sub-layers; and the diameter of the first micro-hole is greater than the diameter of the second micro-hole.

A lens whose size is below the macroscopic resolution limit is called a microlens. The microlenses are preferably developed to be spherical or aspherical, for example in a banknote, advantageously exhibiting a diameter between 5 micrometers (μm) and 100 μm, preferably between 10 μm and 50 μm, in particular The best is between 15 μm and 20 μm. For card applications, the microlenses can also be larger and exhibit a diameter of, for example, between 100 μm and 300 μm. Microlenses can also be developed as cylindrical lenses in all designs.

The diameter of the first microhole is preferably greater than the diameter of the second microhole by more than 10%, especially by more than 20% and particularly preferably by more than 30%. However, the diameter of the first microhole is not more than 4 times larger than the diameter of the second microhole, especially not more than 3 times. Due to the magnifying effect of the microlens, even a small difference between the first and second micropore sizes results in a good contrast difference between the reflected light effect or the transmitted light effect, as explained in more detail below.

In a preferred embodiment, the second microwell has a diameter between 2 μm and 4 μm, and the first microwell has a diameter between 3 μm and 8 μm. For good contrast differences, the diameter of the first microwell is, for example, 0.5 μm to 4 μm larger than the diameter of the second microwell.

In an advantageous embodiment, each microwell is smaller than the associated microlens. Here, the area ratio of the micropores to the associated microlenses may be less than 1.0 or less than 0.5, less than 0.2, or even less than 0.1.

In a simple design, each of the first and second microwells is developed to be substantially circular or linear. However, it is also possible to develop the first and/or second microwells into a pattern shape, for example in a geometric shape, such as a square, a triangle or a star, or in the form of a microtag, such as a word. Parent, number or similar to integrate additional, hidden security features into the secure element. The development of pattern shapes is suitable, especially for larger first microwells.

Although the first microwell is at least in size and also in shape (if appropriate) different from the second microwell, it is advantageous if the first microwell itself has the same shape and size and the second microwell is the same.

The first microhole advantageously forms a first pattern in the form of a pattern, a character or a code, the first pattern being perceptible when viewed from the preselected first viewing direction in reflected light, and The second microhole forms a second pattern in the form of a pattern, a character or a code that is perceptible when the security element is viewed from the preselected second viewing direction in transmitted light. The first and second patterns are generally different, but may be the same. Likewise, the first and second viewing directions are preferably different, but may be the same.

In an advantageous design, the first and second micropores are arranged independently of one another. In other equally advantageous designs, at least a portion of the second microwell is entirely within the first microwell. For example, more than 50%, more than 75%, or all of the second micropores may be located within the first microwell. In this way, a "pattern within the pattern" can be produced in which the transmitted light pattern appears within the reflected light pattern. For example, the security element can include a feather pattern visible in the reflected light and formed by the first microhole, and when viewed to be viewed in transmitted light, can be seen inside the feather pattern by the second A sign of micropore formation. In this case, it is expedient to select the first and second viewing directions to be the same.

In a preferred embodiment, the first and/or second microvias are introduced into the recording layer via laser lens alignment from different directions using laser radiation. When viewed later, the micropores can be perceived in the viewing direction from which they are each introduced in reflected or transmitted light. Here, as already described above, Each of the first microwells may be perceptible from a first viewing direction, and each of the second microwells is perceptible from a different second viewing direction.

However, it is also possible that one set of first micropores is introduced from one direction and the other set of first micropores is introduced from the other direction. The first pattern formed by the first microwell then displays an oblique image or an alternating image whose sub-images are formed by different sets of first microwells. Likewise, embodiments with more than two introduction directions or continuous direction changes are possible. Alternatively or additionally, in the same way, the second microholes can also be introduced from two or more different directions.

Pattern portions or sub-images that are visible from different viewing directions may be associated in a sense, such as in a book flip, the pattern portion or sub-image depicting a sequence of images that are performed in front of the viewer's eyes when the security element is tilted . If the angle of introduction (and therefore the viewing angle) changes continuously, the transparency and thus the brightness of the pattern will also change continuously as the security element is tilted.

Advantageously, the first and second sub-layers of the recording layer are formed by a metal layer, for example by aluminum, copper, silver, gold, chromium, nickel, tungsten, palladium or an alloy of these metals, such as an aluminum-copper alloy. Floor. The first and second sub-layers are advantageously formed by metal layers of different colors, such as aluminum and copper. In order to ensure a particularly good visibility of the reflected light pattern, the second sub-layer is advantageously formed by a high-reflectivity metal layer having a reflectance of 90% or higher, for example by vapor-deposited aluminum or silver layers. form.

The first and/or second sub-layers are advantageously opaque, and when the transmission of a layer in visible light is less than 1%, especially less than 0.1%, it is referred to as opaque.

In an advantageous design, the recording layer consists of the first and second sub-layers and therefore does not comprise additional layers.

However, embodiments are conceivable in which one or more additional layers are disposed between the first and second sub-layers of the recording layer. In particular, one or more layers that are transparent to the laser may be present between the first and second sub-layers, such as a dielectric layer composed of SiO ₂ (ceria). Such additional layers can be used, for example, to produce a particular color and/or color shift effect, and/or as a viscosity enhancing layer. In addition to this, the seed layer can also consist of a plurality of individual layers, which can likewise comprise a neutral layer.

As will be explained in the following detailed description, the difference in diameter or surface area of the microwells in the same recording layer allows for the encoding of two separate security element appearances for reflected light viewing and transmitted light viewing. Briefly summarized, when viewed in reflected light, the viewer sees through the relatively large first micro-hole and sees the highly reflective second sub-layer, while the smaller second micro-hole is not perceived in the reflected light. Especially because of its small size. Thus, due to the high reflectivity of the second sub-layer, the first pattern formed by the first microvia can be clearly perceived in the reflected light while the second pattern is still hidden.

In the transmitted light, sufficient light also passes through the relatively small second micro hole, so that the second pattern formed by the second micro hole can be perceived, and the first micro hole exists in the first sublayer The first pattern of composition is still hidden due to the opacity of the second sub-layer.

Preferably, the first microholes present in the first sub-layer do not extend into the second sub-layer. However, in practice, if the first and second sub-layers are stacked directly on top of each other, the holes extend slightly into the second sub-layer (ie, less than 1/10 or even less than 1/20, for the sake of production). Layer thickness) is harmless. It is only important that the remaining layer thickness of the second sub-layer exhibits a sufficiently high reflectivity and a sufficiently high opacity.

In an advantageous development of the invention, the security element also comprises a micro-optical rendering configuration, in particular a moiré amplification configuration, a moiré-type micro-optical magnification configuration or an analog-to-digital amplification configuration. This The basic principle of a micro-optical depiction configuration is described in the document WO 2009/000528 A1, the disclosure of which is incorporated herein by reference. In this case, the security element preferably exhibits a pattern image divided into a plurality of crystal lattices between the substrate and the recording layer, and an imaging region of a predetermined background pattern is disposed in each of the crystal lattices, and the microlens is arranged to form a microlens grid. a mesh, the microlens grid reconstructing the background pattern from the imaged regions disposed in the lattice when viewing the pattern image.

The pattern image is advantageously present as an embossed pattern in the embossed lacquer layer, the embossed lacquer layer being disposed between the substrate and the recording layer. In this case, it can be provided in particular that the first and second sub-layers are attached to the embossing of the embossing lacquer layer, ie to exhibit substantially the same embossed pattern.

In a variation of the invention, the microlens arrangement can provide a translucent cover layer and/or a cover layer that is only present in certain regions. However, it is presently preferred that the microlens arrangement does not have an applied layer that reduces or counteracts the optical effects of the microlens.

The invention also encompasses a data carrier, in particular a value document, such as a banknote, passport, certificate, identification card or the like, which is provided with a security element of the kind described. In an advantageous variant of the invention, in particular the security element can be arranged in or on a window region or a through opening in the data carrier.

The invention further includes a method of making an optically variable security element for security paper, value documents, and other data carriers, wherein: a substantially transparent substrate is provided, the substrate having opposing first and second major surfaces, Arranging a lens assembly on the first major surface of the substrate; forming a plurality of microholes in the laser sensitive recording layer by laser radiation, wherein each microhole is associated with a microlens, and When the security element is viewed from a viewing angle, the microhole can be seen via an associated microlens; The plurality of micropores comprise a plurality of first micropores and a plurality of second micropores, the first micropores being formed in the first sublayer and not penetrating the recording layer, and the second micropores being Forming the first and second sub-layers penetrating the recording layer; and the first micro-porous system is formed to have a larger diameter than the second micro-hole.

In an advantageous development of the method, the first and/or second micropores are introduced into the recording layer by laser radiation from different directions passing through the microlens array.

In an advantageous method variant, in the first step, initially only the first sub-layer forming the laser-sensitive recording layer on the second main surface of the substrate is provided by the action of laser radiation The plurality of first micropores. In the second step, the second sub-layer of the laser-sensitive recording layer is then disposed on the first sub-layer, and the second micro-hole is formed to pass through the first and second portions of the recording layer. Sublayer.

Another optically variable security element for security paper, value documents, and other data carriers includes: a substantially transparent substrate having opposing first and second major surfaces; an array of microlenses, the a microlens is disposed on the first major surface of the substrate; a laser sensitive recording layer, particularly a metal layer, disposed on the second major surface of the substrate; a printed layer, particularly an ink layer, Arranging on the recording layer; forming a plurality of micropores in the laser-sensitive recording layer by the action of laser radiation, wherein each micro-hole is associated with a microlens, and when viewing the security element from a viewing angle The micropores may be visible via associated microlenses, each microcavity being smaller than the associated microlens; at least one gap region formed in the recording layer by the action of laser radiation, the gap region The dimension is greater than the size of the microlens; the at least one gap region forms a first pattern in the form of a pattern, a character or a code, the first pattern being perceived as having a view when the security element is viewed in reflected and transmitted light The appearance of the printed layer; and the microholes form a second pattern in the form of a pattern, a character or a code that is perceptible only when the security element is viewed from the preselected viewing direction in transmitted light, and From this viewing direction, the first pattern is complemented to form a complete pattern.

The at least one gap region forms a macroscopic pattern visible to the naked eye through the microlens, without the need for an auxiliary device, particularly without the need for magnification. The minimum dimension of the at least one gap is typically above 0.5 mm, typically a few millimeters. The material of the printed layer may, but need not, penetrate into the micropores and/or interstitial regions. The microlens arrangement is preferably an applied layer that does not reduce or counteract the optical effects of the microlens. The recording layer may be, for example, a 50 nm thick aluminum layer, and the printed layer is, for example, an embossed solvent-based red lacquer layer. The security element can be applied to a data carrier that has a certain transmission in transmitted light, such as banknote paper. In an advantageous design, the security element is arranged in or above the window or through hole in the data carrier.

Exemplary embodiments and advantages of the present invention are explained below with reference to the drawings in which the description of scales and scales are omitted to improve their clarity.

10‧‧‧ banknotes

12‧‧‧Optical Variable Security Element

14‧‧‧through hole

20‧‧‧Substrate

22‧‧‧ first major surface

24‧‧‧Second major surface

26‧‧‧Microlens

30‧‧‧Laser-sensitive recording layer

32‧‧‧First sublayer/copper layer

34‧‧‧Second sublayer/aluminum layer

40‧‧‧Micropores

42‧‧‧ first micropores

44‧‧‧Second micropores

46‧‧‧ first pattern

48‧‧‧second pattern

50‧‧‧View directions

52‧‧‧ reference mark

54‧‧‧View directions

56‧‧‧ reference mark

1 is a schematic view of a banknote having an optically variable security element of the present invention disposed above a through hole in the banknote, and FIG. 2 is a cross-sectional view of the layer structure of the security element in accordance with the present invention. schematic diagram, Figures 3(a) and 3(b) are two intermediate steps in the manufacture of the security element of Figure 2, and Figure 4 is a visual appearance of the security element of Figure 2 when viewed from the front, Figures 4(a) and 4(b) The appearance of viewing from two viewing directions in reflected light is illustrated, while FIGS. 4(c) and 4(d) illustrate the appearance viewed from two viewing directions in transmitted light, and FIG. 5 is when viewed from the back. The visual appearance of the security element of Figure 2, Figure 5(a) is in reflected light, and Figure 5(b) is in transmitted light.

The invention will now be explained using a secure element for an example of a banknote. In this regard, FIG. 1 illustrates a schematic view of a banknote 10 having an optically variable security element 12 of the present invention, with security element 12 disposed over a through hole 14 in banknote 10. In transmitted light, the security element 12 appears translucent in the sub-area regardless of the direction of viewing, and since it is placed on the through-hole 14, it can be viewed from the front and from the back, in each case, in Both reflected and transmitted light are acceptable.

Viewed from each of these different viewing directions, the security element 12 displays a different visual appearance, resulting in high attention and recognition value.

FIG. 2 schematically shows, in cross section, the layer structure of the security element 12 according to the invention, in which only the layer structure parts required for the described functional principle are explained.

The security element 12 includes a substantially transparent substrate 20, which is typically formed from a transparent plastic foil, such as a polyethylene terephthalate (PET) foil of about 20 micrometers (μm) thickness. The substrate 20 has opposing first and second major surfaces, and the first major surface 22 is provided with a microlens 26 arrangement. In the illustrated exemplary embodiment, the microlenses 26 are regularly configured in the form of a microlens grid and form a two-dimensional Bravais lattice with pre-selected symmetry on the surface of the substrate foil. The Brafi lattice of the microlens 26 can be expressed For example, hexagonal grid symmetry or lower level symmetry, such as parallelogram grid symmetry.

In the exemplary embodiment, the spherical or aspherical design microlenses 26 preferably have a diameter between 15 μm and 30 μm and thus cannot be perceived by the naked eye. The thickness of the substrate 20 and the curvature of the microlenses 26 are coordinated with each other such that the focal length of the microlenses 26 substantially corresponds to the thickness of the substrate 20.

A laser-sensitive recording layer 30 is disposed on the second major surface 24 of the substrate 20, the laser-sensitive recording layer 30 being composed of two stacked sub-layers, the first sub-layer 32 being disposed on the substrate 20 and the second sub-layer 34 between. The first and second sub-layers 32, 34 are preferably formed of metal layers of different colors, and the second sub-layer has an ultra-high reflectance of 90% or higher. To this end, in the illustrated exemplary embodiment, the first sub-layer 32 is formed of a 100 nm thick copper layer, and the second sub-layer 34 is formed of a 50 nm thick aluminum layer. The layers are vapor deposited onto the substrate 20 in a continuous manner.

In addition, a plurality of circular micropores 40 are introduced into the recording layer 30 by the action of laser radiation. Here, a part of the micropores (hereinafter referred to as the first micro holes 42) exist only in the first sub-layer 32 and do not pass through the recording layer 30. Another portion of the micropores (hereinafter referred to as second microwells 44) pass through the first and second sub-layers 32, 34 of the recording layer 30.

The plurality of first microholes 42 together form a first pattern 46, which in the exemplary embodiment is the logo "G+D" when viewed from the preselected first viewing direction in the reflected light. The first pattern 46 can be perceived (Fig. 4(b)). The plurality of second microholes 44 together form a second pattern 48, which in the exemplary embodiment is a letter pair "PL" when viewing the security element in transmitted light from a preselected second viewing direction (Fig. 5(b)) The second pattern 48 can be perceived.

Here, the first microwell 42 has a diameter of 6 μm, and the second microwell 44 has a diameter of only 4 μm. Therefore, the diameter of the first micropores 42 is (6 μm / 4 μm) = 1.5 times larger than the diameter of the second micropores 44. Therefore, the surface area of the first micropores 42 is (6 μm / 4 μm) ² = 2.25 times larger than the surface area of the second micropores 44. In this way, on the one hand it is achieved that only the first pattern 46 is visible in the reflected light, while the second pattern 48 is not visible. On the other hand, the high reflectance of the first first microhole 42 and the second sub-layer 34 ensures the light appearance of the first pattern.

The visibility of the first and second patterns from only certain preselected viewing directions is a direct result of the production of microvias via the microlenses 26. Referring to FIG. 3, in order to fabricate the security element 12, a 100 nm thick copper layer 32 is first applied to the second major surface of the substrate 20, and a 50 nm thick aluminum layer 34 is applied to the copper layer 32, preferably by vacuum. The vapor deposition process is carried out. At these layer thicknesses, both the copper layer 32 and the aluminum layer 34 are opaque. Further, the aluminum layer 34 exhibits an extremely high reflectance of 90% or more.

The coated substrate is then illuminated from the microlens 26 side from the rear viewing direction 50 required for the second pattern, for example using Nd:YAG, Nd:YVO ₄ or fiber laser radiation. The microlens 26 focuses the laser radiation on the recording layer 30 as indicated by reference numeral 52 in Fig. 3(a). Here, the laser energy or the laser power is selected such that both the first sub-layer 32 and the second sub-layer 34 are ablated to form a circular second microhole 44 having a diameter of 2 to 4 μm passing through the recording layer. Here, the laser beam travels over the surface area of the second pattern 48 such that all of the second microholes 44 form a second pattern 48.

The coated substrate is then illuminated from the microlens 26 side from the rear viewing direction 54 required for the first pattern using laser radiation. The microlens 26 focuses the laser radiation onto the recording layer 30 as indicated by reference numeral 56 in Figure 3(b). In this step, the laser energy or laser power is selected such that substantially only the first sub-layer 32 is ablated and the second sub-layer 34 is not ablated. for example, In order to create a first microhole 42 having a larger surface area, the direction of illumination of the laser can be annularly tilted by a small amplitude relative to the desired viewing direction 54. In this way, a circular first micropores having a diameter of 3 to 8 μm are produced. Furthermore, the laser beam travels over the surface of the first pattern 46 such that the entire first microhole 42 forms a first pattern 46.

In this way, the creation of the microholes 42, 44 after laser illumination via the associated microlenses 26 is achieved with the respective microholes 42, 44 and, due to the reversibility of the beam path, is visible when viewing the security element later Micropores.

In a variant of an alternative method (not shown here), in order to manufacture the security element 12, a 100 nm thick copper layer 32 is first applied to the second major surface of the substrate 20, preferably by vacuum vapor deposition. The process is carried out. The substrate of the coated copper layer 32 is then irradiated with laser radiation from the microlens 26 side from the rear viewing direction 54 required for the first pattern, for example using Nd:YAG, Nd:YVO ₄ or fiber laser radiation. Microlens 26 focuses the laser radiation onto first sub-layer 32. Here, the laser energy or the laser power is selected such that the first sub-layer 32 is ablated and a circular first micropore having a diameter of 3 to 8 μm is formed. For example, to create a first microhole 42 having a larger surface area, the direction of illumination of the laser can be annularly tilted by a small amplitude relative to the desired viewing direction 54. Here, the laser beam travels over the surface area of the first pattern 46 such that the entire first microhole 42 forms the first pattern 46.

Thereafter, a 50 nm thick layer of aluminum 34 is applied to the copper layer 32, preferably vapor deposited. The coated substrate is then illuminated from the microlens 26 side from the rear viewing direction 50 required for the second pattern using laser radiation. The microlens 26 focuses the laser radiation on the recording layer 30. Here, the laser energy or the laser power is selected such that both the first sub-layer 32 and the second sub-layer 34 are ablated to form a circular second microhole 44 (diameter 2 to 4 μm) that passes through the entire recording layer 30. . Here, the laser beam travels on the surface of the second pattern 48 such that all of the second microholes 44 form a second pattern 48.

Figure 4 illustrates the visual appearance of the security element 12 produced in this manner when viewed from the first (front) side of the first major surface 22. 4(a) and 4(b) illustrate the appearance viewed from two viewing directions (ie, in reflection) in reflected light, and FIGS. 4(c) and 4(d) are illustrated in transmitted light. The appearance viewed from two viewing directions (ie in transmission).

In the reflected light, the viewer sees the microlenses 26 from the viewing direction 54 (Fig. 3(b)) and sees the microholes 42 of the first sub-layer 32, thereby seeing the underlying second sub-layer 34. Due to the high reflectivity of the second sub-layer 34 and the relatively large surface area of the first microhole 42, from the direction 54, the first pattern (marker "G+D") is brightly visible and has good contrast, and in the first sub- The copper background of layer 32 is silver front, as shown in Figure 4(b).

The first microhole 42 is invisible in the reflected light when viewed from another viewing direction that does not correspond to the preselected viewing direction 54 of the first pattern, since in this case the viewer will see through the microlens 26 and see The first sub-layer 32 is at a location other than the micro-holes 42. Since the surface area of the second microwell 44 in the reflected light is relatively small, the second microwell 44 is less conspicuous or completely imperceptible. In general, from such a viewing direction, the security element 12 thus appears as a uniform copper surface, as depicted in Figure 4(a). By tilting the security element 12 back and forth in the reflected light, the viewer can change between the appearances of Figures 4(a) and 4(b).

In the transmitted light, the recording layer 30 is translucent due to the plurality of second micro holes 44, regardless of the viewing direction. In this viewing direction, since the microholes 44 are viewed through the microlenses 26, the light incident from the back side in each case is substantially the angle formed by the micropores when the microholes are generated using a laser beam. The holes 44 are illuminated. Therefore, when viewed in the viewing direction 50 (Fig. 3(a)) in transmission, the second pattern (letter string "PL") formed by the second micropores is visible light against the dark background of the metal recording layer 30, As shown in Figure 4 (d).

The second microvia 44 is invisible in transmitted light when viewed from another viewing direction that does not correspond to the preselected viewing direction 50 of the second pattern, because in this case, the viewer sees through the microlens 26 and sees One or the second sub-layer is at a location other than the micro-holes 44. Both the first and second sub-layers are opaque such that the security element 12 appears as a uniform, dark surface from such viewing direction, as depicted in Figure 4(c). By tilting the security element 12 back and forth in the transmitted light, the viewer can change between the appearance of Figures 4(c) and 4(d).

For viewers, the different appearances in reflected and transmitted light are unusual and surprising, and thus produce a visually appealing and compelling overall impression with high attention and discernibility .

Figure 5 illustrates the visual appearance of the security element 12 when viewed from the second (back) side of the second major surface 24, Figure 5 (a) illustrates the appearance in reflected light, and Figure 5 (b) illustrates the transmitted light The appearance in the middle.

In the reflected light, the second sub-layer 34, which is only silver from the back side, is visible because, due to the small size of the second micro-hole 44, it is not perceptible through the second micro-hole 44 in the reflected light. Thus, in the reflected light, the viewer sees a uniform layer of silver metal 34 from the back, as illustrated in Figure 5(a).

When viewed in transmitted light, the security element 12 is shown translucent through the plurality of second microholes 44 over a wide range of angles. Contrary to when viewed from the front, the second microholes 44 are not visible through the microlenses 26 when viewed from the back. Conversely, the microlens 26 collects light incident from the first major surface 22 and focuses the incident light onto the second microhole 44 such that a wide angle range is created in which the second pattern 48 formed by the microholes 44 emerges from the back. Bright.

The first microhole 42 does not pass through the recording layer 30, so that the second sublayer is opaque 34. The first pattern 46 is not perceived from the back side and is not perceived in transmitted light. In summary, the viewer thus sees a string of letters "PL" shining against the dark background against a wide range of angles, as illustrated in Figure 5(b). Since the second pattern appears to be reversed when viewed from the back side, it is preferred to select a mirror-symmetric pattern or a mirror-neutral pattern as the second pattern, that is, a pattern that is not affected by the mirror image, such as a geometric pattern, a building, a technique, or a natural pattern. .

In a variant, the angle of viewing and thus the viewing angle of the first and/or second microholes may be continuously varied in the dimensions of the first or second patterns 46, 48 in one or even two spatial directions. Such continuous changes can be achieved, such as a suitable deflection system via laser radiation. The brightness of the first or second pattern 46, 48 then changes continuously as the security element is tilted and viewed in reflected or transmitted light.

12‧‧‧Optical Variable Security Element

22‧‧‧ first major surface

24‧‧‧Second major surface

26‧‧‧Microlens

30‧‧‧Laser-sensitive recording layer

32‧‧‧First sublayer/copper layer

34‧‧‧Second sublayer/aluminum layer

40‧‧‧Micropores

42‧‧‧ first micropores

44‧‧‧Second micropores

Claims (21)

An optically variable security element for security paper, value documents, and other data carriers, comprising: a substantially transparent substrate having opposing first and second major surfaces; an array of microlenses, the a microlens is disposed on the first major surface of the substrate; a laser sensitive recording layer disposed on the second major surface of the substrate, the laser sensitive recording layer comprising stacked first and second sublayers The first sub-layer is disposed between the substrate and the second sub-layer; a plurality of micro-holes formed in the laser-sensitive recording layer by the action of laser radiation, wherein each micro-hole and a micro-lens Associated, and when viewing the secure element from a viewing angle, the microhole can be seen via an associated microlens; the plurality of microwells comprising a plurality of first microwells and a plurality of second microwells, the first micro a hole system exists in the first sub-layer and does not penetrate the recording layer, and the second micro-hole penetrates the first and second sub-layers of the recording layer; and the diameter of the first micro-hole is larger than the The diameter of the second micropore. The security element according to claim 1 is characterized in that the diameter of the first microhole is larger than the diameter of the second microhole by more than 10%, in particular by more than 20%, and particularly preferably by more than 30%. . A security element according to claim 1 or 2, wherein the first microhole forms a first pattern in the form of a pattern, a character or a code, when viewed from a preselected first viewing direction in the reflected light. The first pattern is perceptible when the security element is present, and wherein the second microhole forms a second pattern in the form of a pattern, a character or a code, when viewed in a transmitted light from a preselected second viewing direction The second pattern is perceptible when the security element is in use. A security element according to at least one of claims 1 to 3, characterized in that the first and/or second micropores are introduced into the recording layer by laser radiation from different directions passing through the microlens array. And in that the microlens is perceptible in reflected or transmitted light when viewed from an individual viewing direction. A security element according to at least one of claims 1 to 4, characterized in that each of the first and second microholes is substantially circular or patterned. A security element according to at least one of the claims 1 to 5, characterized in that each of the microholes is smaller than the associated microlens. A security element according to at least one of claims 1 to 6, characterized in that the area ratio of the micropores to the associated microlenses is less than 1.0 or less than 0.5 or even less than 0.2. A security element according to at least one of claims 1 to 7, characterized in that the second micropore is located in the first micropore at 50% or more and preferably 75% or more. A security element according to at least one of claims 1 to 8, characterized in that the first and second sub-layers are formed of metal layers of different colors. A security element according to at least one of claims 1 to 9, wherein the second sub-layer is formed of a highly reflective metal layer having a reflectance of 90% or more. A security element according to at least one of the claims 1 to 10, characterized in that the first and/or second sublayers are opaque. A security element according to at least one of claims 1 to 11, characterized in that a pattern image is provided between the substrate and the recording layer, the pattern image being divided into a plurality of crystal lattices in each of the crystal lattices An imaging region of a predetermined background pattern is disposed, the microlens arrays forming a microlens grid, and the microlens grid reconstructs the background pattern from the imaging regions disposed in the lattice when viewing the pattern image. The security element of claim 12, wherein the pattern image is present as an embossed pattern in a raised lacquer layer between the substrate and the recording layer. The security element of claim 13 is characterized in that the first and second sub-layers are attached after the relief of the embossing lacquer layer. A security element according to at least one of claims 1 to 14, characterized in that the microlens arrangement is provided with a semi-transparent cover layer and/or a cover layer present only in certain areas. A security element according to at least one of the claims 1 to 14, characterized in that the microlens arrangement has no applied layer which reduces or counteracts the optical effect of the microlens. A data carrier having a security element according to at least one of claims 1 to 16. The data carrier of claim 17 is characterized in that the security element is disposed in or above a window region or a through hole in the data carrier. A method of making an optically variable security element for security paper, value documents, and other data carriers, wherein: a substantially transparent substrate having opposing first and second major surfaces is provided An array of microlenses is disposed on the first major surface of the substrate; a laser sensitive recording layer is disposed on the second major surface of the substrate, the laser sensitive recording layer comprising the first stacked And a second sub-layer disposed between the substrate and the second sub-layer; forming a plurality of micro-holes in the laser-sensitive recording layer by laser radiation, wherein each micro-layer a hole is associated with a microlens, and when viewed from a viewing angle, the microhole can be seen via an associated microlens; The plurality of micropores comprise a plurality of first micropores and a plurality of second micropores, the first micropores being formed in the first sublayer and not penetrating the recording layer, and the second micropores being Forming the first and second sub-layers penetrating the recording layer; and the first micro-porous system is formed to have a larger diameter than the second micro-hole. The method of claim 19, wherein the first and/or second micropores are introduced into the recording layer by laser radiation from different directions passing through the microlens array. The method of claim 19 or 20, wherein in the first step, only the first sub-layer of the laser-sensitive recording layer is formed on the second main surface of the substrate by the ray The effect of the radiant radiation provides the plurality of first micropores, and in a second step, the second sub-layer of the laser-sensitive recording layer is disposed on the first sub-layer, and the second micro-pore is formed To pass through the first and second sub-layers of the recording layer.