Christopher L Langston

US Patent:

58830430, Mar 16, 1999

Filed:

Aug 27, 1997

Appl. No.:

8/919041

Inventors:

Wendell B. Halbrook - Waynesville OH
Christopher L. Langston - Jackson TN
Maurice W. Lewis - Dayton OH
Yaoping Tan - Miamisburg OH

Assignee:

NCR Corporation - Dayton OH

International Classification:

B41M 530

US Classification:

503204

Abstract:

A thermal paper with an image derived from a water-based security ink has more than one means of security. A variable light absorbing and/or transmitting pigment or dye in the ink is a first security and a water repelling agent in the ink is a second security. A pseudo-watermark from the coloration of the ink under ambient conditions is a third security. Visible images can be generated from the printed ink upon exposure to UV or infrared light. Methods of preparing the thermal paper comprise printing the security ink on thermal paper with only one thermosensitive coating on the surface opposite the thermosensitive coating.