A new read/write concept for vertical recording

A novel read/write concept for vertical recording in rigid disk drives is described that makes it possible to write very short magnetic transitions in double-layer media. The occurrence of magnetic saturation zones inside the poles of the thin-film head are chosen so that the head writes an asymmetrical magnetic transition with a very steep field edge. The readback signal reproduced by the combination of an asymmetrical head and an asymmetrical transition is defined by the reciprocity theorem. The asymmetry of the reading characteristics of the head is determined by the design. If the poles and the gap are suitably dimensioned, the asymmetrical effects can be made to compensate each other, and nearly antisymmetrical readback pulses are produced. Hence this head/disk combination makes possible recording densities of more than 100 Mb/in²