Method and apparatus for authenticating and discriminating currency

摘要

A system for authenticating documents comprises in one embodiment an ultraviolet light source illuminating a document to be tested, an ultraviolet light detector for detecting the ultraviolet light reflected by the document and a signal processor for determining the authenticity of the document based upon an output signal of the ultraviolet light detector representing the amount of detected ultraviolet light. The document is considered genuine if the output signal is within a predetermined range of an expected value. In another embodiment, the system combines the ultraviolet light source and ultraviolet light detector with a visible light detector for detecting visible light emitted by the document. The signal processor receives signals from both the ultraviolet detector and the visible light detector and determines the authenticity of the document based upon signals representing the reflected ultraviolet light and detected visible light. The document is considered genuine if the output signal representing the detected ultraviolet light is within a predetermined range of an expected value and if the output signal representing the amount of visible light does not exceed a threshold value.