Influence of remanence magnetization on asymmetry of reproducing signals in 4MB FDD heads

A head combined with a read/write (R/W) gap and a pre-erase gap has been adopted for 4 MB flexible disk drives. The cross-talk coupling from the erase head to the R/W head can be suppressed by decreasing the permeability of the head material. However, decreasing the permeability of the erase head material increases the coercive force. Therefore, a remanence magnetization is induced in the erase head core during the reproducing process, which increases the asymmetry of reproduced waveforms. In order to decrease this asymmetry, a head with back gaps is developed. By controlling the back gap length to minimize the cross-talk, it is possible to realize both low asymmetry and low cross-talk simultaneously for 4 MB FDD heads