Design of magnetic recording heads for high track densities

Head positioning accuracy may be the factor which most limits track densities in a magnetic recording system. Inaccurate head positioning results in coherent noise from adjacent and previously written tracks. We describe an approach to head design which minimizes noise from these sources, increasing the track density attainable from a given servo system. Tests are defined to evaluate heads by measuring the ratio of signal to noise from adjacent and previously written tracks. Expressions involving head read and write widths are derived for these two signal-to-noise ratios, and their predictions agree well with the test results. The two expressions are simultaneously maximized resulting in constraints on the head widths. Read and write widths of a dual gap thin film head can be adjusted to satisfy these constraints and achieve higher track densities.