High chroma optically variable color-shifting glitter comprising particles having interference structure coating
Opaque glitter particles that are uniform in size and shape are disclosed that have an optically variable color with a change in angle of incident light. The glitter particles have an organic substrate and an optical interference structure on one or both sides of the organic substrate. The optical interference design can be a Fabry-Perot structure or can be an optically variable ink.
1. Opaque color shifting glitter comprising particles, cut such that their shape and size is substantially uniform, said particles each comprising an inorganic thin film optical interference structure for providing a perceivable color shift with a change in viewing angle or angle of incident light, in the visible spectrum, wherein said inorganic thin film interference structure of each particle is supported by an organic support layer for providing rigidity and for preventing the particles from curling and wherein the inorganic thin film interference structure of each particle is only on one side of the organic support layer.
2. Opaque color shifting as defined in claim 1 wherein each particle has length across its surface of 30 microns or more, and wherein the thickness of the particles are at least 6 microns.
3. Opaque color shifting glitter as defined in claim 2 , wherein the thin film interference structure is a Fabry-Perot interference structure.
4. Opaque color shifting glitter as defined in claim 2 , wherein the thin film interference structure includes two Fabry-Perot interference structures.
5. Opaque color shifting glitter as defined in claim 4 , wherein the two Fabry-Perot structures share a common reflector layer.
6. Opaque color shifting glitter as defined in claim 4 , wherein the Fabry-Perot structures each have a dielectric layer and wherein the thicknesses of the dielectric layers are substantially different.
7. Opaque color shifting glitter as defined in claim 1 wherein the inorganic thin film optical interference structure is a layer of optically variable ink.
8. Opaque color shifting glitter as defined in claim 1 , wherein the organic support layer has a diffraction grating or a holographic structure formed therein.
9. Opaque color shifting glitter as defined in claim 8 , wherein the diffraction grating or the holographic structure is formed on a surface of the organic support layer and wherein the inorganic thin film optical interference structure supported by the organic support layer has the diffraction grating or the holographic structure formed in at least a layer thereof.
10. Opaque color shifting glitter as defined in claim 9 , wherein the organic support layer is light transmissive and wherein the inorganic thin film interference structure comprises a color shifting Fabry-Perot structure that can be seen from both sides of a particle.
11. Opaque color shifting glitter as defined in claim 8 , wherein the diffraction grating or the holographic structure is formed on a first face of the organic support layer and wherein the inorganic thin film optical interference structure is supported on an opposite face of the organic support layer.
12. Opaque color-shifting glitter comprising particles having: an organic support layer and;
a) two single or double period Fabry-Perot structures sharing a same reflector layer on only one side of the organic support layer or
b) an optically variable color shift ink on only one side of the organic support layer.
13. Opaque color shifting glitter as defined in claim 12 , wherein the particles each comprise two symmetrical optically variable structures (SOVSs) each SOVS including an inner reflector layer and an outwardly facing absorber layer, and a dielectric layer disposed there between, said particles each having an diameter “d” of at least 30 microns, and a thickness “t” of more than 6 microns wherein t<d/2, the organic support layer providing rigidity for preventing the particles from curling and for lessening chipping and breaking of the particles.
14. Opaque color shifting glitter as defined in claim 13 , wherein the two symmetrical SOSVs share an inner reflector layer.