CN116568520A - Optically variable security element and method for producing an optically variable security element - Google Patents

Abstract

The invention relates to an optically variable security element, which has a layer sequence when viewed from the top. The layer sequence comprises a microstructure (2) providing a visual object visible from the upper side, the microstructure having a period of 2 μm to 50 μm and being achromatic. Furthermore, the layer sequence has a reflective layer (4) and a viewing-angle-dependent layer (6; 14) which are arranged on the microstructure (2), the reflective layer reflecting incident light, wherein the reflective layer (4) or the viewing-angle-dependent layer (6; 14) has at least one recess (15) and the other of the two layers is unstructured, wherein the layer having the recess (15) is located above the unstructured other layer, as viewed from the top. Instead of the recesses and the reflective layer, the security element can have an unstructured viewing-angle-dependent layer (6; 14) and an unstructured partially light-transmitting reflective layer (16; 18).

Description

Optically variable security element and method for producing an optically variable security element

The invention relates to an optically variable security element having a microstructure providing a visual object visible from above, a reflective layer and a viewing angle-dependent layer. Furthermore, the invention relates to a method for producing or producing a corresponding optically variable security element.

An optically variable security element is known from EP 1506096 B1. Through the combination of the achromatic surface structure and the film structure, a defined color change is effected when the security element is rotated or tilted.

A security element is likewise known from WO 01/03945 A1. The combination of the diffractive surface structure and the underlying layer with color-changing properties produces a visual effect in order thereby to increase the counterfeit security of the security element.

An optically variable security element is also known from EP 2390106 A2. The optically variable effect is generated by a combination of a diffractive surface structure coated with a thin metallization such that it remains partially light-transmissive, with a thin-film structure.

The invention is intended to provide an optically variable security element and a method for producing an optically variable security element which, when viewed from above, has a layer sequence and a microstructure.

The invention is defined in the independent claims. Advantageous developments are specified in the dependent claims. The preferred embodiment is suitable for the optically variable security element and the method for producing the optically variable security element.

An optically variable security element having a layer sequence and a microstructure is provided. The microstructure presents at least one visual object (or pattern) on the upper side of the optically variable security element. The microstructures are, for example, embossed into an embossing varnish on the carrier substrate. The microstructure has structural elements arranged at regular intervals, ie periodically with a period of 2 μm to 50 μm. Each individual structural element is unique in itself, they do not have to all be the same. The term "periodically" relates only to the arrangement of structural elements at regular intervals.

The structural elements are designed individually, for example inclined relative to a main plane determined by the substantially planar design of the carrier substrate, such that the structural elements together represent at least one visual object. According to the present application, when the microstructure is observed in a cross-sectional view, the periodic microstructure is also, for example, a sawtooth structure or a corrugated structure with a unique tooth slope. With a period of 2 μm to 50 μm, diffraction phenomena only affect the optical properties to a lesser extent.

Each structural element serves, for example, as a pixel arranged on the surface of the carrier substrate. The pixels are arranged periodically. Each pixel forms, for example, an optically active sub-mirror and, through its orientation, produces a unique optical effect, so that a plurality of visual objects or visual object movements or visual object effects are rendered by the microstructures as a function of the tilt angle.

The microstructure is achromatic. Achromatic microstructures produce no color effects. They appear colorless to the observer. Thus, although the microstructures provide visual objects that are visible from above, especially as a function of oblique angles, the visual objects are not polychromatic due to the absence of color effects due to the achromatic nature of the microstructures. Examples of achromatic microstructures are achromatic blazed structures, symmetrical microstructures (eg sinusoidal grids) or matt structures. Blazed structures (eg sawtooth grids) and achromatic symmetrical microstructures (eg sinusoidal grids) are preferably used as achromatic microstructures.

In the method for producing an optically variable security element, the described microstructure is formed on a carrier substrate. This is preferably achieved by embossing, for example in embossing varnish.

The layer sequence of the optically variable security element has a reflective layer and a viewing angle-dependent layer.

The reflective layer can have at least one of the following layers: a metallic layer, a colored layer that produces a polychromatic visual sensory impression, and a colored/transparent resist.

The reflective layer interacts with the microstructures to change the intensity of the incident light and thus makes visual objects produced by the action of the microstructures more visible to the naked eye. The visual object is thus visible in the region of the security element in which the reflective layer is present. The high refractive layer is a reflective layer.

Viewing angle-dependent layers produce a color impression that is dependent on the viewing angle (so-called OVD). The color of the region of the optically variable security element in which the viewing angle-dependent layer is visible changes depending on the illumination or viewing direction.

Preferably, the viewing angle-dependent layer is designed as a color-shifting layer system having a layer sequence consisting of a partially light-transmitting reflector layer, a dielectric spacer layer and a reflector layer. Preferably, the viewing angle-dependent layer has an optically variable ink which produces a viewing angle-dependent color effect. Optically variable inks are preferably colorless substances mixed with optically variable pigments. The pigments have, for example, a symmetrical thin-layer structure which, through interference effects, enables a viewing-dependent color change, for example from green to blue or from magenta to green. The pigments are present, for example, in the form of platelets and their lateral dimensions are preferably in the range from 1 μm to 200 μm, particularly preferably in the range from 10 μm to 50 μm. The thickness of the platelets is preferably in the range from 200 nm to 10 μm, particularly preferably in the range from 350 nm to 1500 nm.

The optically variable security element thus comprises the microstructure embodied on/in the carrier substrate and the stated layer sequence having a reflective layer and a viewing angle-dependent layer. The reflective layer and the viewing angle-dependent layer can be designed in two variants.

In a first variant, both layers are located above the microstructure, and the upper layer, ie the reflective layer or the viewing angle-dependent layer, has at least one cutout. The other of the two layers is unstructured. In the layer sequence, the layer with the cutouts is located above the unstructured further layer, viewed from the top. Unstructured means that this layer has no cutouts. However, it is entirely possible for this layer to be embossed, ie to have a structured surface.

The cutout enables the optical effect of the lower layer to be seen in the cutout and the optical effect of the upper layer to be seen outside the cutout. The cutout thus produces the second visual object.

If the upper layer is a viewing angle-dependent layer, the optically variable security element is perceived from above with a viewing angle-dependent coloring. In the cutout, only the lower reflective layer in the layer sequence is active, so that when viewed from above, the visual objects produced by the reflective layer are perceived in the cutout, but not the viewing angle-dependent colors that are otherwise present impression. The second visual object is therefore a cutout in which there is no OVD color impression.

If the upper layer is a reflective layer, the visual object is visible from above, but does not have the OVD color impression due to the covering effect of the reflective layer. Conversely, in the cutouts, the lower viewing angle-dependent layers play a role, so that in the cutouts a viewing angle-dependent color impression is perceived, but the visual object is not perceived due to the absence of a reflective layer there. Perceived. In this case, viewing angle-dependent color effects only appear in the cutouts.

In the method for producing an optical security element according to a first variant, a reflective layer is applied to the microstructure and a viewing angle-dependent layer is applied to a carrier substrate or to the reflective layer, wherein at the reflective layer or at the viewing angle At least one cutout is provided in the relevant layer and the other of the two layers remains unstructured. In this case, the layer provided with the cutout is located above the unstructured further layer, viewed from the top. This makes manufacturing easier and contributes to the effect of anti-counterfeiting security.

If, in the first variant, the cutouts are arranged in the reflective layer or in the viewing angle-dependent layer, the area coverage of the cutouts should preferably be between 10% and 90%, particularly preferably between 30% and 70%. between.

The cutouts in the reflective layer or the viewing angle-dependent layer can be produced in different ways, as will be explained below. Of course, several cutouts can also be produced.

In one alternative, prior to the application of the layer, a cleaning ink is printed onto the microstructures in the regions in which cutouts are to be produced in the layer. This layer is applied to the microstructures after the cleaning ink has been applied to these areas. The cleaning ink is then removed from the microstructures by contacting the cleaning ink with a medium in which the cleaning ink is soluble, such as water, whereby in the regions where the microstructures were printed with the cleaning ink, the upper layer is also removed. Adjacent regions of the layer below which no cleaning ink has been applied are not affected here.

In a further alternative, after the layer has been applied to the microstructure, a resist is applied regionally (in the regions where the cutouts are not to be produced) in order to open the cutouts into the layer . In a subsequent etching step, only the regions not covered by the resist are etched, so that cutouts are produced in this layer.

In another alternative, the cutouts in this layer are produced by laser ablation. In this case, short light pulses with high intensity are guided over the surface of the reflective layer in a grid-like manner, so that the reflective layer is removed at the exposed locations and thus form cutouts in the reflective layer. In this case, short laser pulses with high intensity are scanned over the region in which the cutout is to be provided. In the area covered by the laser pulse, the layer is removed and, when viewed from the upper side, the layer below the layer becomes visible.

In a further alternative, the cutouts in the layers are produced by transfer. In this case, the surface of the microstructure is treated or coated before applying the layer in such a way that the adhesion of the layer is reduced. A film with good adhesion properties is then structured according to the cutouts to be formed in that the region in which the cutout is to be formed protrudes axially beyond the other regions and presses the protruding region of the film directly against the On a microstructure with a layer thereon. The structured film is subsequently removed again, and the layer is detached from the microstructure in the treated regions and remains attached to the structured film in the protruding regions, thus forming cutouts. In the case of opposite adhesion properties, preferably the same effect can be achieved. This means that the metal is first applied to the structured film (which has an axially protruding and lowered surface area) and is then partly transferred to the microstructures in a way that the microstructures have more in the area than the structured film. Good adhesion properties. In other alternatives for transfer, the region in which the cutout is to be provided is designed as a planar region which protrudes axially beyond the adjacent structured region. Films with better adhesion properties can then be designed unstructured and the metal only removed from the raised planar regions of the microstructure. When using colored inks, the microstructures can also be printed directly with the desired cutouts.

If cutouts are produced in the viewing angle-dependent layer, this is preferably achieved by first coating the microstructures with a reflective layer and then partially overprinting the microstructures with an optically variable ink. Thus, when viewed from the top, the optically variable ink is perceived or seen in the regions and the reflective layer applied on the microstructures is seen in the cutouts.

In embodiments, optically variable inks can also be applied over the entire surface with a lower particle density. In this case, the particle density is chosen such that a certain proportion of the surface of the reflective layer is covered with particles and the remaining surface remains uncovered. Surface coverages of 10-90%, preferably 30-70%, can be achieved by correspondingly diluting the ink or concentrating the pigments in the matrix. This also achieves the effect that both the region of the optically variable ink and the region of the reflective layer are visible when viewed from the top.

The region without the cutout can have any shape, wherein the size of the region in at least one dimension is preferably between 5 μm and 200 μm, particularly preferably between 20 μm and 100 μm. The area coverage of the printed areas is preferably in a value range of 5% to 95%, particularly preferably in a value range of 40% to 60%.

In a second variant of the optically variable security element, the reflective layer on the microstructure is designed as an unstructured, but partially light-transmissive layer on its surface, and the viewing angle-dependent layer is at a microscopic level when viewed from the top. below the structure. The view-dependent layers are also unstructured. In a second variant, the incident light is not completely reflected by the reflective layer, but the reflective layer reflects part of said incident light and transmits part of said incident light. The reflective layer is partially transparent and unstructured in this regard. This variant requires no structuring steps at all and still shows good results because the visuals have OVD color effects.

In the method of the second variant for producing an optically variable security element, an unstructured, partially light-transmissive reflective layer is applied to the microstructure and an unstructured viewing angle-dependent layer is applied to the On the carrier substrate, this is achieved, for example, by a bonding step, so that the viewing angle-dependent layer is axially below the microstructure coated with the reflective layer.

In a second variant, the microstructure is preferably coated over the entire surface with a partially light-transmissive reflective layer consisting of a transparent material with a high refractive index. The partially light-transmitting reflective layer preferably has a refractive index greater than 2. An example of such a partially transparent reflective layer is a ZnS coating. The coating is preferably applied to the microstructures by vacuum evaporation. The thickness of the high refractive layer is preferably in the range of 1 nm to 100 nm, particularly preferably in the range of 10 nm to 50 nm. Such partially light-transmissive reflective layers respectively reflect and transmit a substantial portion of incident light. Thus, on the one hand, the optically variable effect of the microstructure coated with a partially light-transmitting reflective layer remains visible, thereby producing a visual object, and on the other hand, the viewing angle-dependent layer arranged below the microstructure produces such an optical effect, That is, when the entire area is viewed from the upper side, the entire area is perceived as having coloring depending on the viewing angle. Here, the viewing angle-dependent layer can preferably be designed as a color-shifting layer system, as already described; however, the viewing angle-dependent layer can also be an optically variable ink.

In a further preferred embodiment of the second variant, the partially light-transmissive reflective layer can be a thin metal layer whose layer thickness is selected such that incident light is only partially reflected on this layer. The effect is then similar to that produced by highly refractive coatings. The thin metal layer preferably has a layer thickness of 1 nm to 30 nm, particularly preferably a layer thickness of 1 nm to 8 nm. The metal is preferably applied to the microstructures by vacuum evaporation.

Preferably, the partially transparent layer can also be additionally structured. This can be achieved, for example, by the methods already described, namely laser ablation, application of cleaning inks, etching or the like. From this, other visual objects can be generated.

Insofar as a cutout is referred to here, it can also comprise a plurality of cutouts which are not connected to one another.

The invention is explained in more detail below by way of example with reference to the drawings. In the attached picture:

FIG. 1 shows an optically variable security element in a first variant in a sectional view;

FIG. 2 shows the optically variable security element in a first variant when viewed from the top;

FIG. 3 shows an optically variable security element in a further embodiment of the first variant in a sectional view;

FIG. 4 shows an optically variable security element in a further embodiment of the first variant when viewed from the top;

5 and 6 show an optically variable security element in a second variant in cross-sectional view; and

FIG. 7 shows the optically variable security element in a second variant when viewed from the top.

FIG. 1 shows an optically variable security element in a sectional view. Microstructure 2 and layer sequence can be seen. The microstructures 2 providing visual objects are located on the carrier substrate 1 , usually on the upper side of the carrier substrate. The microstructures 2 are applied, for example, in an embossing varnish on the carrier substrate 1 . The design scheme of microstructure 2 has been described. The microstructures 2 are regionally coated with a reflective layer 4 which renders the visual object provided by the microstructures 2 visible, so that at least one cutout 15 is provided in the coated region, in which cutout In this case, the reflective layer 4 is not applied to the microstructure 2 at first or is subsequently removed. Further visual objects are generated through this cutout 15 . The reflective layer 4 can preferably have at least one of the following layers: a metal layer, a colored layer that produces a polychromatic visual sensory impression, a monochromatic or transparent resist.

The viewing angle-dependent layer is arranged below the carrier substrate 1 , generally on its bottom side. The viewing angle-dependent layer itself does not produce a visual object, but imparts to the optically variable security element a color impression which is dependent on or depends on the viewing angle of the observer. For example, the viewing angle-dependent layer in FIG. 1 is a color-shifting layer system 6 consisting of a partially light-transmitting reflector layer 8 , a dielectric spacer layer 10 and a reflector layer 12 . Alternatively, the viewing angle dependent layer may be an optically variable ink 14 . The composition of the optically variable ink 14 has already been described.

FIG. 2 shows the optically variable security element shown in sectional view in FIG. 1 as viewed from the top. If the security element in FIG. 1 is viewed from above, the reflective layer 4 can be seen in some regions and the cut-out 15 with the color arranged below the reflective layer 4 can be seen in some other regions. Layer transfer system6.

In the optically variable security element according to FIGS. 1 and 2 , microstructures 2 are formed on a carrier substrate 1 . The microstructures are preferably imprinted in an embossing varnish on the carrier substrate 1 by an embossing process, for example. The microstructures 2 have a period of 2 μm to 50 μm and are achromatic. The structure of Microstructure 2 has already been described. The microstructure 2 provides at least one visual object, but due to its achromatic nature, appears colorless when viewed from above. An example of an achromatic microstructure 2 has also been explained. Flare structures can be described regionally as linear structures and can be identified as saw-tooth profiles in cross-sectional view (see Figure 1). Since the period of the microstructure 2 is 2 μm to 50 μm, the diffraction phenomenon has only a slight influence on the optical properties. Thus, microstructures 2 act like tilted mirrors; they produce no color effect. By coating the microstructures 2 with a reflective layer 4, the visual objects provided by the microstructures 2 are made visible.

View-angle-dependent layers produce a color impression for the observer that depends on the viewing angle. The provision of cutouts 15 ensures that, in regions where cutouts 15 are not provided, visual objects produced by the interaction of reflective layer 4 with microstructures 2 are visible when viewed from above and are retained by the viewing angle-dependent layer. A viewing angle-dependent color impression is formed in the cutout 15 . A visual object is thus produced by the cutout 15 . In general, rasterized views, such as halftone images, are also possible in addition to microscopically rasterized cutouts, macroscopic cutouts. This cutout 15 in the reflective layer 4 can be produced in various ways, as already explained. Possibilities for producing the cutouts 15 are the application of cleaning ink, the application of a resist in areas where no cutouts are to be made, the generation of the cutouts 15 by laser ablation, or the transfer already described. It is also possible to produce a plurality of cutouts 15 whose shape is arbitrary here. The area coverage of the cutout 15 is, for example, in the range of 10% to 90%, particularly preferably in the range of 40% to 60%.

FIG. 3 shows a cross-sectional view of another embodiment of an optically variable security element. The microstructures 2 are applied to the carrier substrate 1 as in FIG. 1 . The microstructure 2 is now coated over its entire surface, generally on its upper side, with a reflective layer 4 . The reflective layer 4 is unstructured here. Optically variable ink 14 or another viewing angle-dependent coating is located in regions on reflective layer 4 , thus forming cutouts 15 . FIG. 4 shows the optically variable security element according to FIG. 3 viewed from above. The optically variable ink 14 can be seen here and the underlying reflective layer 4 can be seen in the cutout 15 .

In this embodiment, reflective layer 4 is partially covered with optically variable ink 14 . Here, all common printing methods are suitable, but special attention must be paid to the accuracy of the register. Preferably, the optically variable ink 14 can also be printed on the entire surface of the reflective layer 4 and then structured by laser ablation. In this case, high-intensity short laser pulses are scanned over the area where the optically variable ink 14 is to be removed or modified, so that the cutout 15 is formed. The optically variable ink 14 can preferably also be applied over the entire surface with a lower particle density. Here, the particle density is selected such that a certain proportion of the areas of the particles are covered and the remaining areas remain uncovered (see above).

If a cutout 15 is provided in the viewing angle-dependent layer, in the cutout 15 the reflective layer 4 lying below the viewing angle-dependent layer in the layer sequence becomes visible when viewed from above, said reflective layer being applied on a microscopic Structure 2 and the resulting visual object. In regions where no cutouts 15 are provided, the viewing angle-dependent layer produces a color impression that is dependent on the viewing angle. In this case, therefore, the cutout 15 also produces a visual object.

5 and 6 show a second variant of the optically variable security element. As in the first variant, in the embodiment of FIG. 5 the microstructures 2 are applied to the carrier substrate 1 . The high-refractive layer 16 is applied as a partially light-transmissive reflective layer on the microstructure 2 , usually as an unstructured layer on the upper side of the microstructure. The partially light-transmissive reflective layer reflects and transmits part of the incident light. In the embodiment of FIG. 6 , a partially light-transmissive reflective layer is likewise provided, in this case in the form of a thin, unstructured metal layer 18 . The viewing angle-dependent layer is arranged on the underside of the carrier substrate 1 . In the exemplary embodiment of FIG. 5 , the viewing angle-dependent layer is designed as an optically variable ink 14 . In the case of FIG. 6 , the viewing angle-dependent layer is designed as a color-shifting layer system 6 .

FIG. 7 shows a second variant of an optically variable security element having the structure according to FIGS. 5 and 6 , viewed from above. In the area 20, both the optical effect caused by the combination of the partially light-transmitting reflective layer and the microstructure 2 (creating the visual object) and the viewing angle-dependent color caused by the viewing angle-dependent layer can be seen Effect. In this variant, no cutouts 15 are provided either in the partially light-transmissive reflective layer or in the viewing angle-dependent layer. Both layers are unstructured.

In the embodiment according to FIGS. 5 and 7 , the microstructure 2 is coated over the entire surface with a translucent material with a high refractive index, whereby a partially light-transmissive reflective layer is formed. Such a highly refractive coating 16 reflects and transmits, respectively, a substantial portion of the incident light. Thus, on the one hand, the optically variable effect of the microstructure 2 coated with the high-refractive coating 16 remains visible (creating the visual object), and on the other hand, the optically variable ink 14 arranged underneath ensures that the entire area is covered. The viewer is perceived as a coloration that depends on the viewing angle. High refractive coating 16 preferably has a refractive index greater than 2. An example of a high refractive coating 16 is a ZnS coating. The material is preferably applied to the microstructures 2 by vacuum evaporation. The thickness of the high-refractive layer 16 may be in the range of 1 nm to 100 nm, particularly preferably in the range of 10 nm to 50 nm. Alternatively, the high-refractive layer can also be additionally structured. This can be achieved by the already described methods of laser ablation, application of cleaning ink or etching.

In a preferred embodiment, according to FIGS. 6 and 7 , a thin metal layer 18 is applied to the upper side of the microstructure 2 . This produces almost the same effect as the coating of the microstructure 2 with the high-refractive coating 16 . The layer thickness is chosen to be so thin that incident light is only partially reflected on the thin metal layer 18 , so that the visual object can still be seen by the microstructure 2 coated with the reflective layer 4 . Part of the incident light is thus reflected and part of the incident light is transmitted, so that the color-shifting layer system 6 arranged below the carrier substrate 1 enables the entire area 20 to be perceived as a coloring depending on the viewing angle when viewed from above . Instead of the color-shifting layer system 6 , an optically variable ink 14 can preferably also be arranged below the microstructures 2 . The thin metal layer 18 should preferably have a layer thickness of 1 nm to 30 nm, particularly preferably a layer thickness of 1 nm to 8 nm. A thin metal layer 18 is preferably applied to the microstructures 2 by vacuum evaporation.

list of reference signs

1 carrier substrate

2 Microstructure

4 reflective layers

6 color shifting layer system

8 partially transparent reflector layers

10 dielectric spacers

12 reflector layers

14 optically variable inks

15 blank part

16 high refraction layers

18 thin metal layers

20 areas

Claims (12)

1. An optically variable anti-counterfeit element, said anti-counterfeit element has - providing a microstructure (2) of the visual object visible from the upper side, - a reflective layer (4) and a viewing angle dependent layer (6; 14) arranged on the microstructure (2), said reflective layer reflecting incident light, It is characterized in that, - said microstructure (2) has a period of 2 μm to 50 μm and is achromatic, and - the reflective layer ( 4 ) or the viewing angle-dependent layer ( 6 ; 14 ) has at least one cutout ( 15 ) and the other of the two layers is unstructured, wherein there is a cutout The layer of (15) lies above the unstructured further layer, viewed from the top. 2. An optically variable anti-counterfeit element, said anti-counterfeit element has - providing a microstructure (2) of the visual object visible from the upper side, - an unstructured, partially light-transmissive reflective layer (16; 18) arranged on the microstructure (2), and - an unstructured view-dependent layer (6; 14), wherein the view-dependent layer (6; 14) is located below the microstructure (2) viewed from the upper side, It is characterized in that, - said microstructure (2) has a period of 2 μm to 50 μm and is achromatic. 3. Optically variable security element according to claim 2, characterized in that the partially light-transmissive reflective layer is a high-refractive layer (16). 4. Optically variable security element according to claim 2, characterized in that the partially transparent reflective layer is a thin metal layer (18). 5. The optically variable security element as claimed in claim 1, characterized in that the viewing angle-dependent layer (6; 14) is a color-shifting layer system (6). 6. Optically variable security element according to one of claims 1 to 4, characterized in that the viewing angle-dependent layer comprises an optically variable ink (14). 7. A method for producing an optically variable security element, wherein - applying microstructures (2) providing visual objects visible from the upper side on/in the carrier substrate (1), - applying a reflective layer (4) on the microstructure (2), said reflective layer reflecting incident light, and - applying a viewing angle-dependent layer (6; 14) to a carrier substrate or reflective layer (4), characterized in that, - said microstructure (2) has a period of 2 μm to 50 μm and is achromatic, and - at least one cutout (15) is opened in the reflective layer (4) or the viewing angle-dependent layer (6; 14) and the other of the two layers remains unstructured, wherein a cutout is opened The layer of the cavity ( 15 ) lies above the unstructured further layer, viewed from above. 8. A method for producing an optically variable security element, wherein - applying microstructures (2) providing visual objects visible from the upper side on/in the carrier substrate (1), - applying an unstructured, partially light-transmitting reflective layer (16; 18) to the microstructure (2), and - applying an unstructured viewing angle-dependent layer (6; 14) to the carrier substrate (1), wherein said viewing angle-dependent layer (6; 14) is located below the microstructures (2) viewed from the top, It is characterized in that, - said microstructure (2) has a period of 2 μm to 50 μm and is achromatic. 9. The method for producing an optically variable security element according to claim 8, characterized in that the partially light-transmissive reflective layer is a high-refractive layer (16). 10. The method for producing an optically variable security element according to claim 8, characterized in that the partially light-transmissive reflective layer is a thin metal layer (18). 11. The method for producing an optically variable security element according to claim 7, characterized in that the viewing angle-dependent layer is a color-shifting layer system (6). 12. The method for producing an optically variable security element according to claim 7, characterized in that the viewing angle-dependent layer (6; 14) has an optically variable ink (14).