Vacuum Roll Coated Security Thin Film Interference Products With Overt And/Or Covert Patterned Layers
A security article provides a covert feature as well as an optically variable effect on one side thereof and a mirror-like reflective effect on another side. The article includes an interference filter consisting of a first reflective layer, a dielectric layer on the first reflective layer, and an absorber layer on the dielectric layer. Furthermore, the article includes a magnetic layer under the first reflective layer for providing the covert feature, and a second reflective layer under the magnetic layer for providing the mirror-like reflective effect. The magnetic layer may be patterned, and a third reflective layer, also patterned, may be formed on the absorber layer for providing a visual reference for the color shifting image.
1 . A security article for providing a covert feature comprising:
an interference filter on a first side thereof, consisting of
a first reflective layer,
a dielectric layer on the first reflective layer,
an absorber layer on the dielectric layer,
for providing an optically variable effect on the first side;
a magnetic layer under the first reflective layer for providing the covert feature, and
a second reflective layer under the magnetic layer for providing a mirror-like reflective effect on a second side thereof.
2 . A security article as defined in claim 1 , wherein the magnetic layer is a patterned magnetic layer.
3 . A security article as defined in claim 2 , wherein the patterned magnetic layer is patterned using an oil-ablation process.
4 . A security article as defined in claim 2 , wherein the patterned magnetic layer has a thickness of less than about 5.0 microns.
5 . A security article as defined in claim 2 , wherein the patterned magnetic layer is patterned by a one dimensional magnetic bar code pattern.
6 . A security article as defined in claim 2 , wherein the patterned magnetic layer is patterned by a two-dimensional magnetic bar code pattern.
7 . A security article as defined in claim 2 , wherein the patterned magnetic layer is patterned by a logo pattern.
8 . A security article as defined in claim 2 , wherein the patterned magnetic layer is a magnetic signature.
9 . A security article as defined in claim 1 , wherein the magnetic layer contains machine readable information for verifying the authenticity of the thread or sheet.
10 . A security article as defined in claim 1 , further comprising a patterned opaque layer on the absorber layer, wherein the opaque patterned layer is visibly distinguishable from the interference filter for providing a visual reference to the optically variable effect.
11 . A security article as defined in claim 10 , wherein the patterned opaque layer is a patterned reflective layer and the visual reference is a mirror-like visual reference.
12 . A security article as defined in claim 11 , wherein the patterned reflective layer is formed of a reflective material.
13 . A security article as defined in claim 12 , wherein the reflective material is aluminum.
14 . A security article as defined in claim 10 , wherein the patterned opaque layer is patterned using an oil-ablation process.
15 . A security article as defined in claim 1 , wherein the second reflective layer is formed of a reflective material.
16 . A security article as defined in claim 15 , wherein the reflective material is aluminum.
17 . A security article as defined in claim 1 , further comprising a substrate between the interference filter and the second reflective layer.
18 . A security article as defined in claim 17 , further comprising a third reflective layer, wherein the magnetic layer is sandwiched between the second and third reflective layers.