Granted Patent B2

US 8,153,984 · App. 12/337,752 · Granted Apr 10, 2012

Abstract

Claims (9)

1. A security system comprising:

a security marker material comprised of emissive particles and the emissive particles are grouped into at least two groups with different size distributions and the size distributions satisfy the formula:

[( x−z ) 2 /(S x 2 +S z 2 )] 1/2 >1

wherein x and z are the volume-weighted mean equivalent-spherical diameters of the two particle distributions and S x and S z are the standard deviations of the same two distributions;

placing the emissive materials in or on an item;

exciting the emissive materials with electromagnetic radiation in one or more specified spectral bands;

detecting electromagnetic radiation in a one or more spectral bands from the emissive materials in an image-wise fashion.

2. The security system of claim 1 wherein the item is one of the following: a printed label, a cardboard box, a woven label, a document, an ID card, a pharmaceutical container, a thread, a film, a hologram, a color shifting ink patch.

3. The security system of claim 1 wherein the emissive material is applied to an item by printing or spraying.

Assignments (18)