Multi-tapped magnetoresistive heads for magnetic tape tracking servo

A multi-tapped magnetoresistive (MR) stripe has been commercially fabricated as a tape head for evaluation as a potential tracking sensor for magnetic tape systems with dedicated servo. In this approach, two adjacent MR elements sharing a common bias current are each positioned halfway over a single 17.5 μm wide servo track. The head leads provide signals from each of the MR elements which are separated 1.25 μm by permanent magnets that provide longitudinal bias. Since this servo configuration uses a differential sensor with a simple square wave tracking pattern, the system can allow self servo formatting. The evaluation of these heads on a Metrum test stand with 1550 Oe Sony MP media has revealed a number of important features to consider in using such a head. On-track isolated transition responses of the multi-tapped elements are shown to be comparable to those from standard individual MR heads fabricated on the same wafer. Cross-track signal profiles show that two adjacent elements in the multi-tapped head can provide an approximately linear tracking error signal within ±4 μm of track center. Finally, sample position error signal results demonstrate the potential of this type of servo scheme