Improved control of magnetic printed sheets

摘要

Banknotes printed with magnetic ink pass through a tricolor age detector 34, and then between a pair of premagnetization rollers (10,12) having opposite magnetic polarity of such strength that the magnetic signature of all banknotes is enhanced to the same level; the notes are then stacked 50 in an electromagnetic stacker 42. Such notes, having magnetic signatures of the same level, can also be recognised and/or validated by magnetic techniques also. <IMAGE>