Security paper for currency and banknotes

DETAILED DESCRIPTION The invention comprises the encoding of printed information onto a strip of clear plastic film which is later incorporated within the paper during the papermaking process.
The printed information can be visually read or machine detected.
The methods of detection include differences in transmission optical density, differences in capacitance, and variations in the electrical current within a tuned resonance circuit.
The encoded information is confined within a narrow band on the plastic film which can be accurately located within currency, banknote or security paper without interferring with the speed of modern paper manufacturing equipment.
In one embodiment, the printed information is a legible phrase, the letters of which are comprised of vacuum metalized aluminum having a thickness of 300-400 angstroms.