Abstract: The present invention may be regarded as a disk drive with protection against damage due to a thermal asperity. The disk drive comprises a disk having a surface with an asperity, and a magneto-resistive head actuated radially over the surface of the disk for generating a read signal comprising a thermal asperity component caused by the magneto-resistive head contacting the asperity on the surface of the disk. A bias generator is provided for generating an electrical bias applied to the magneto-resistive head, and a thermal asperity detector detects the thermal asperity component in the read signal. When the thermal asperity component is detected, the electrical bias is reduced for a time interval, thereby protecting the magneto-resistive head.

Abstract: A method and apparatus is provided which introduces a relative skew between a servo pattern and a magneto-resistive (MR) head in order to reduce interference introduced by inductive reading of shields formed as part of the MR head. The relative skew may be accomplished by introducing a skew angle directly on the head or by skewing the servo pattern formed on the magnetic medium relative to the head. Various skewed patterns may be used to reduce the overall interference.

Abstract: A method and apparatus is disclosed for adaptively controlling the biasing current applied to magnetoresistive (MR) read heads within a magnetic disk drive to provide optimized bias for each head/disk/channel component combination. An optimized bias current for each head is ascertained and stored on the disk surface at the time of manufacture. During each power up operation the values are transferred to random access memory which is accessed during the execution of each head switch command to apply bias current in accordance with the optimized value to the active MR head. Periodic reoptimization and updating of the stored values is effected by general error measurement circuitry that forms a part of the device control system and is invoked to perform the reoptimization upon the occurrence of an event such as a predetermined duration of power on operation subsequent to the last reoptimization procedure.

Abstract: A magnetic thin film recording medium is provided for longitudinal recording of magnetic flux transitions, with the read-back signals enhanced due to a substantial reduction in media noise. The reduced noise level is the result of a unique vacuum deposition process for applying an underlayer to a substrate, prior to deposition of the magnetic thin film. In particular, the underlayer is deposited in a low temperature plasma process under increased pressure of argon or another inert gas and at reduced deposition rates, thus to create voids or interstitial areas which substantially isolate individual grains from their neighboring grains. The subsequently deposited magnetic thin film replicates the crystalline structure and orientation of the chromium underlayer, for relatively isolated grains in the recording layer. This results in lower media noise levels, approaching or equalling those characteristic of particulate media.