To improve the non-repeatable runout (NRRO), repeatable runout (RRO), and nonlinearity of the position signal in hard-disk drives (HDDs), we established criteria for the off-track direction and for the bit direction. Position-signal nonlinearity and NRRO degradation are largely due to the interaction between track width, erase band size, and the sensitivity distribution of the head. So one criterion is for position-signal sensitivity. The other criterion is for burst-bit density, which causes RRO degradation. Using these criteria to compare, theoretically and experimentally, the effectiveness with which the quality of the position signal could be maintained using amplitude and phase patterns confirmed that the phase pattern is superior to the amplitude pattern.
展开▼
