Optically variable element and the use thereof
First Claim
1. An optically variable element comprising:
- a surface portion having an interface which forms an optically effective structure, with respect to a reference surface the optically effective structure at least one of projects and is set back therefrom, wherein the optically effective structure has at least one free-form surface appearing three-dimensionally to a viewer, wherein the free-form surface is formed by a partial region of the interface, which is of a lens-like configuration and which produces a magnification or reduction effect and which forms a free-form element, wherein the free-form element includes a grating structure having grating lines substantially following contour lines of the free-form surface, wherein the grating structure includes grating grooves with first and second opposed flanks, the first flanks extending parallel to each other and substantially parallel to a normal to the reference surface, the second flanks disposed at an oblique angle with respect to the normal to the reference surface, wherein the oblique angle of each of the second flanks either increases or decreases progressively away from a central region of the free-form surface towards an edge thereof, thereby changing the spacing of the grating lines from the central region toward the edge.
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Accused Products
Abstract
The invention relates to an optically variable element which at least in surface portions has an interface embedded between two layers and which forms an optically effective structure, that interface having a free-form surface which appears three-dimensionally for a viewer. To emphasise that free-form surface the invention provides that the free-form surface is formed by a partial region of the interface, which is of a lens-like configuration and which produces a magnification, reduction or distortion effect. The invention also provides the use of such optically variable elements as a security element to prevent forgery of value-bearing documents or for articles to be safeguarded, in particular as part of the decorative layer arrangement of a transfer or laminating film.
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Citations
20 Claims
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1. An optically variable element comprising:
a surface portion having an interface which forms an optically effective structure, with respect to a reference surface the optically effective structure at least one of projects and is set back therefrom, wherein the optically effective structure has at least one free-form surface appearing three-dimensionally to a viewer, wherein the free-form surface is formed by a partial region of the interface, which is of a lens-like configuration and which produces a magnification or reduction effect and which forms a free-form element, wherein the free-form element includes a grating structure having grating lines substantially following contour lines of the free-form surface, wherein the grating structure includes grating grooves with first and second opposed flanks, the first flanks extending parallel to each other and substantially parallel to a normal to the reference surface, the second flanks disposed at an oblique angle with respect to the normal to the reference surface, wherein the oblique angle of each of the second flanks either increases or decreases progressively away from a central region of the free-form surface towards an edge thereof, thereby changing the spacing of the grating lines from the central region toward the edge. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. An optically variable element comprising:
a plurality of surface portions forming an interface to produce an optically effective structure, the optically effective structure spatially projects from and/or is set back with respect to a reference surface, the optically effective structure including at least one free-form surface, the at least one free-form surface appearing to a viewer as a three-dimensional free-form element, wherein the at least one free-form surface is formed by a partial region of the interface, the at least one free-form surface having a lens-like configuration and produces at least one of a magnification and reduction effect and which forms the free-form element, wherein the free-form element includes a grating structure having grating lines substantially following contour lines of the free-form surface, wherein the spacing of the grating lines either increases or decreases progressively away from a central region of the free-form surface substantially to an edge thereof, wherein the grating structure of the free-form element is a binary structure having grating grooves and grating lands which are of substantially rectangular cross-section. - View Dependent Claims (18, 19, 20)
Specification