Disk drive using the thermal signal from an MR-head as a radial position sensor

The thermal response of a magnetoresistive (MR) head can be used to detect disk defects in a disk drive. An extension of this result is to use the thermal response for the detection of topographical track boundaries for the purpose of track following and seeking during magnetic recording in a disk drive. A special disk, called a Pre-Embossed Rigid Thermal (PERT) disk uses embossed patterns in the grooves between mesa-like tracks. The groove-embossed patterns produce modulation in the MR element-to-disk spacing and therefore a detectable modulation in the thermal response from an MR head