OPTICALLY EFFECTIVE SURFACE RELIEF MICROSTRUCTURES AND METHOD OF MAKING THEM
First Claim
1. Element having at least one surface area with an optically effective surface relief microstructure, which surface relief microstructure has a surface modulation of transitions from top regions to bottom regions and from bottom regions to top regions,wherein at least in one lateral direction of the surface area there is at least one transition from a top region to a bottom region or vice versa within every 20 micrometer,characterized in that(i) the lateral arrangement of the transitions is non-periodic, and(ii) the top regions substantially lie in a top relief plateau and the bottom regions substantially lie in a bottom relief plateau, such that the relief modulation depth is substantially equal over the surface area.
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Accused Products
Abstract
The present invention relates to an element comprising a surface area with a specific, optically effective surface relief microstructure (12). The surface relief microstructure has a surface modulation of top regions (13) and bottom regions (14), wherein in a first lateral direction of the surface area there is in average at least one transition from a top to a bottom region or vice versa within every 20 micrometer, and in a second lateral direction of the mask, which is perpendicular to the first direction, there is in average at least one transition from a first to a second zone or vice versa within every 200 micrometer. In the microstructure, (i) in the first direction the lateral arrangement of the transitions is non-periodic, and (ii) the top regions substantially lie in the same top relief plateau (15) and the bottom regions substantially lie in the same bottom relief plateau (16).
Through scattering effects, the surface relief microstructures are suitable to display images with a positive-negative image flip, which advantageously have a distinct and saturated color appearance but at the same time do not show any rainbow colors.
The invention also relates to methods for making such elements as well as to security devices comprising such elements
37 Citations
42 Claims
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1. Element having at least one surface area with an optically effective surface relief microstructure, which surface relief microstructure has a surface modulation of transitions from top regions to bottom regions and from bottom regions to top regions,
wherein at least in one lateral direction of the surface area there is at least one transition from a top region to a bottom region or vice versa within every 20 micrometer, characterized in that (i) the lateral arrangement of the transitions is non-periodic, and (ii) the top regions substantially lie in a top relief plateau and the bottom regions substantially lie in a bottom relief plateau, such that the relief modulation depth is substantially equal over the surface area.
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29. Security device comprising an element having at least one surface area with an optically effective surface relief microstructure, which surface relief microstructure has a surface modulation of transitions from top regions to bottom regions and from bottom regions to top regions,
wherein at least in one lateral direction of the surface area there is at least one transition from a top region to a bottom region or vice versa within every 20 micrometer, characterized in that (i) the lateral arrangement of the transitions is non-periodic and (ii) the top regions substantially lie in a top relief plateau and the bottom regions substantially lie in a bottom relief plateau, such that the relief modulation depth is substantially equal over the surface area.
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31. Method for making an element having at least one surface area with an optically effective surface relief microstructure, which method comprises:
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creating a mask, which has a microstructure of first and second zones of different transparency, wherein in at least one, preferably in a in a first lateral direction of the mask there is, preferably in average, at least one transition from a first to a second zone or vice versa within every 20 micrometer, and preferably in a second lateral direction of the mask, which is perpendicular to the first direction, there is in average at least one transition from a first to a second zone or vice versa within every 200 micrometer, and wherein in the preferably first direction the lateral arrangement of the transitions is non-periodic; generating with the help of the mask a relief microstructure in the surface of a resin or resist to produce top regions corresponding to the first zones of the mask and bottom regions corresponding to the second zones of the mask, wherein the top regions substantially lie in a top relief plateau and the bottom regions substantially lie in a bottom relief plateau, such that the relief modulation depth is substantially equal over the whole surface area. - View Dependent Claims (32, 33, 34, 35, 37)
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Specification