Printed security with hallmarks

US4591707A · kind A · utility

Assignee

• GAO Gesellschaft für Automation und organisation mbH · DE

Inventors

• Gerhard Stenzel · Germering, DE
• Wittich Kaule · Grafing, DE

Key dates

• Filing date: Aug 23, 1984
• Grant date: May 27, 1986
• Expiry date: Aug 23, 2004

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S283/904
• WIPO field: Textile and paper machines
• WIPO sector: Mechanical engineering

Abstract

This invention relates to a security paper with a hallmark in the form of a coating applied by vacuum deposition techniques to the surface of a paper substrate. The coating is very thin and almost invisible to the naked eye even as a metal layer, although permitting accurate automatic or machine examination for verification purposes. the absorption of the hallmarks in a certain range of the wavelength of the spectrum, the exiting spcetrum of luminescence, the photoconductivity and/or the electrical conductivity of the hallmarks are characteristics used during the automatic examination of the authenticity of the security paper.