Method and apparatus are used to detect and identify coded patterns on articles such as bank notes, in the form of magnetic regions (e.g., small areas printed with ink containing magnetic pigment). The apparatus includes a mechanism for passing a given article rapidly past a scanning location where a...http://www.google.com.tw/patents/US5545885?utm_source=gb-gplus-share專利 US5545885 - Method and apparatus for detecting and identifying coded magnetic patterns on genuine articles such as bank notes
