Patterned optical structures with enhanced security feature
First Claim
1. A security article comprising:
- a substrate;
a diffractive grating directly on the surface of the substrate or upon a coating adjacent to the substrate, having a first region and a second region adjacent to the first region;
wherein the first region is coated with a high refractive index (HRI) coating of a light reflecting HRI material having an index of refraction at least 1.65 and where the second region is absent the HRI material thereby forming a window above the second region of the substrate;
a colored or color shifting coating supported by the substrate and visible through the window;
whereby, when the article is irradiated with light, an image formed by light reflected from the colored or color shifting coating in the window provides a reference to a holographic image formed by light reflected from the HRI coating.
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Accused Products
Abstract
A security article is a substrate having a diffractive grating thereon, coated with a windowed high index layer and a color shifting coating visible through the window. The color shifting coating is disposed on the high index layer or on the opposite side of the substrate. Alternatively, a thin film color shifting structure conforming the diffractive grating is disposed between the grating and the windowed high index layer, also conforming to the shape of the diffractive grating. Alternatively, an ink with low density of color shifting pigments is applied over the high index layer conforming to the shape of the diffractive grating. The resulting color shifting image provides a reference to a holographic image.
160 Citations
10 Claims
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1. A security article comprising:
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a substrate; a diffractive grating directly on the surface of the substrate or upon a coating adjacent to the substrate, having a first region and a second region adjacent to the first region;
wherein the first region is coated with a high refractive index (HRI) coating of a light reflecting HRI material having an index of refraction at least 1.65 and where the second region is absent the HRI material thereby forming a window above the second region of the substrate;a colored or color shifting coating supported by the substrate and visible through the window; whereby, when the article is irradiated with light, an image formed by light reflected from the colored or color shifting coating in the window provides a reference to a holographic image formed by light reflected from the HRI coating. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification