Methods for forming security articles having diffractive surfaces and color shifting backgrounds

• US 20040094850A1
• Filed: 11/12/2003
• Published: 05/20/2004
• Est. Priority Date: 07/08/1999
• Status: Active Grant

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Inventors: Phillips, Roger W., Markantes, Charles T., Bonkowski, Richard L., Higgins, Patrick K.
• Granted Patent: US 7,754,112 B2
• Time in Patent Office: Days
• US Class Current: 264/1.34
• CPC Class Codes: B42D 2035/24 Colours
• CPC Class Codes: B42D 25/29 Securities; Bank notes
• CPC Class Codes: B42D 25/324 Reliefs
• CPC Class Codes: B42D 25/328 Diffraction gratings; Holograms
• CPC Class Codes: B42D 25/36 comprising special materials
• CPC Class Codes: B42D 25/369 Magnetised or magnetisable materials
• CPC Class Codes: B42D 25/373 Metallic materials
• CPC Class Codes: G03H 1/0011 for security or authentication holograms on information-bearing cards B42D25/328; testing papers with holograms G07D7/0032
• CPC Class Codes: G03H 1/02 Details of features involved during the holographic process; Replication of holograms without interference recording
• CPC Class Codes: G03H 1/0244 Surface relief holograms replicating hologram without interference recording G03H1/0276
• CPC Class Codes: G03H 1/0256 having specific functional layer
• CPC Class Codes: G03H 2250/12 Special arrangement of layers
• CPC Class Codes: G03H 2250/42 Reflective layer G03H2250/36 takes precedence
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/24479 including variation in thickness
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]

Abstract

A security article includes a light transmissive substrate having a first surface and an opposing second surface, with the first surface having an embossed region with an optical diffraction pattern or a holographic image pattern. A color shifting optical coating is formed on the substrate such as on the opposing second surface, with the optical coating providing an observable color shift as the angle of incident light or viewing angle changes. The security article can be used in a variety of applications and products to provide for enhanced security measures such as anticounterfeiting.

Claims

1. A method of forming a security article, comprising the steps of:

providing a light transmissive substrate having a first surface and an opposing second surface, the first surface having an optical interference pattern; and

forming a color shifting optical coating on the second surface of the substrate, the optical coating providing an observable color shift as the angle of incident light or viewing angle changes.

2. The method of claim 1, wherein the optical interference pattern is formed by embossing a diffraction grating pattern or a holographic image pattern on the first surface of the substrate.

3. The method of claim 1, wherein the color shifting optical coating is formed by depositing an absorber layer on the second surface of the substrate, depositing a dielectric layer overlying the absorber layer and depositing a reflector layer overlying the dielectric layer.

4. The method of claim 1, wherein the color shifting optical coating is formed by depositing a first absorber layer on the second surface of the substrate, depositing a dielectric layer overlying the absorber layer and depositing a second absorber layer overlying the dielectric layer.

5. The method of claim 1, wherein the color shifting optical coating is formed by applying a color shifting ink comprising a plurality of multilayer color shifting flakes dispersed in a polymeric medium to the second surface of the substrate.

6. The method of claim 1, wherein the color shifting optical coating is formed on the second surface of the substrate by coextruding a color shifting material comprising a plurality of multilayer optical interference flakes dispersed in a polymeric medium, with a material forming the substrate.

7. The method of claim 1, further comprising the steps of forming a release layer on the substrate, and of hot stamping the security article to an object.