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Electrochemical Printing of Confidential Information

IP.com Disclosure Number: IPCOM000048750D
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Kightlinger, DS: AUTHOR [+2]

Abstract

The formation of a printed character when using an electrochemical process can be divided into two distinct steps: the electrogeneration of a leuco (colorless) oxidant and the conversion of a leuco dye into a colored, visible dye. The oxidant serves as a catalyst to ultimately color a leuco dye that then constitutes the printed matter. It is known that these two steps can be physically separated. Further, it is known that the oxidant is created, and is therefore available, only at or near a positive electrode.

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Electrochemical Printing of Confidential Information

The formation of a printed character when using an electrochemical process can be divided into two distinct steps: the electrogeneration of a leuco (colorless) oxidant and the conversion of a leuco dye into a colored, visible dye. The oxidant serves as a catalyst to ultimately color a leuco dye that then constitutes the printed matter. It is known that these two steps can be physically separated. Further, it is known that the oxidant is created, and is therefore available, only at or near a positive electrode.

Thus, if a positive electrode is given the shape of a desired character, the oxidant formation will approximate the character's shape. Additionally, if the oxidant is formed in the presence of an absorbtion medium, such as paper, the character-shaped oxidant will be absorbed by the medium.

Because the character-shaped oxidant is still colorless, the absorbed character cannot be seen. However, the character can be rendered visible or developed by coating the paper surface with a leuco dye. When this is done, the oxidant in the paper catalyzes a reaction in the dye compound that renders the dye visible in the shape of the character.

Employing this concept, confidential documents can be rendered selectively readable by only those people that can develop the document. It is important to note that many oxidants and compatible leuco dyes are known. Varying the degree of security is therefore made possible by sw...