Apparatus and method for detecting a security feature in a currency note

摘要

An apparatus and method for detecting watermark and security thread in a currency note. Optical sensing circuits positioned from the surface of the currency note rely upon the transmissive and reflective characteristics of the security features and the note itself to determine the authenticity of the note and the security feature. The apparatus and methods determine a difference signal between the transmissive and reflective light signals and compare the difference signal to a series of known difference signals.