Machine-detectable security marking with an increased level of proof against forgery, production of the security marking, and security system comprising this security marking

US6570648B1 · kind B1 · utility

Assignee

• Wacker Chemie AG · DE

Inventors

• Christoph Muller-Rees · Pullach, DE
• Jurgen Kupfer · Berlin, DE
• Horst Leigeber · Oberhaching, DE
• Georg Schwalb · Birkenfeld, DE

Key dates

• Filing date: Nov 20, 2000
• Grant date: May 27, 2003
• Expiry date: May 14, 2021

Classification

• Technology area (CPC G): Physics
• CPC primary: G03G21/043
• WIPO field: Other consumer goods
• WIPO sector: Other fields

Abstract

The invention relates to a security marking whose level of proof against forgery is increased relative to known security markings, comprising liquid-crystalline material with chiral phase, wherein present within the security marking are at least two liquid-crystalline materials with chiral phase which differ in at least one property selected from the group consisting of handedness, color and color flop and which are arranged in the form of a structured or unstructured marking or a multilayer marking or in the form of liquid-crystalline pigments in a liquid-crystalline matrix, or wherein there is at least one liquid-crystalline material with chiral phase whose reflection band has been broadened by means of special techniques, or wherein there is at least one liquid-crystalline material with chiral phase which has a defined three-dimensional arrangement.