Stray field and DC remanent suppression in high-speed magnetic tape duplicator apparatus having an array of permanent magnets productive of a spatially varying transfer field

摘要

An array of an odd number of alternatingly polarized permanent magnets of equal pole strength, disposed in side by side relationship, provides a spatially varying magnetic transfer field for a master and slave tape wrapping a rotatable capstan. First and second terminator magnets, located, respectively, at opposite ends of the array, are similarly polarized with respect to each other, but opposite the polarization of the end magnets of the array. Furthermore, each terminator magnet has a magnetic moment that is less than the magnetic moment of each magnet in the array. Each terminator magnet serves (1) to suppress stray magnetic fields associated with the corresponding end magnet in the array, and (2), in combination with the odd number of alternatingly polarized magnets in the array, to suppress DC residual magnetization in the slave tape.