Hgst Netherlands, B.v.

Xiaotian Sun

Toshiki Hirano

Fu-Ying Huang

Tetsuo Semba

Thomas R Albrecht

A disk drive is described that uses a vibration sensor to generate a compensating feed-forward control signal to synchronize the write clock frequency with the modulated data island frequency. A linear vibration sensor is positioned with its sensitivity axis aligned with the tangential direction of a track at the radial position of the write head. The tangential component of the external linear vibration is measured by the sensor. The feed-forward control signal derived from the linear vibration sensor modifies the control voltage input to VCO (voltage controlled oscillator) in the write clock generator to adjust the write clock frequency to compensate for the modulated data island frequency caused by the tangential component of the linear vibration.

Disk drive with write clock frequency compensation for external vibration disturbance

A system and method of establishing write timing in a disk drive using bit patterned media and a magnetic head with read-write offset in which servoing and writing occur on different tracks with timing offsets. Initially, the distance between the servoing and writing tracks is determined for each track/head position in accordance with head geometry and skew angle. The relative timing errors are then measured by iteratively writing data at timing offset increments to determine the optimal timing offset for the servoing/writing track pair, and then writing the offset to sync fields on the servoing tracks of the disk.

System and method of synchronized writing on bit patterned media with read-write offset

A magnetic data storage system having a magnetic disk having burst patterns for providing a position error signal (PES) wherein each magnetic burst pattern is offset from an adjacent burst pattern by &#xbc; track pitch. All of the magnetic bits of the burst patterns can be unipolar magnetized, and the bits of each burst pattern can be aligned with one another in radial and circumferential direction. The magnetic media can be a bit patterned media wherein the magnetic bits of the burst patterns are magnetically isolated portions separated by non-magnetic spaces or non-magnetic material.

Method for creating burst magnitude servo patterns with unipolar bits on a magnetic media of a magnetic data recording system

A magnetic recording disk drive has three vibration sensors mounted to the disk drive base to provide feedforward vibration compensation signals. First and second spaced-apart sensors are aligned generally parallel to a radius from the disk rotational axis to a head position on the disk between the inside diameter position (h) and outside diameter position (h) for detecting rotational vibration about the disk rotational axis and linear vibration in the cross-track direction. A third vibration sensor is aligned generally orthogonal to the primary axes of the first and second vibration sensors for detecting primarily linear vibrations in the along-the-track or track circumferential direction. The disk drive servo control processor calculates, from the signals from the three sensors, a rotational vibration feedforward signal, a radial linear vibration feedforward signal, and a circumferential linear vibration feedforward signal which are summed with the actuator control signal to compensate for the vibrations.

Magnetic recording disk drive with three sensors for rotational and linear vibration compensation

A disk drive and a method for operating the disk drive compensates for rotational vibration (RV) by adaptively modifying the gains of two separate linear vibration sensors so the sensor gains are optimal under any given condition. The two sensors provide two signals S, S, respectively, to the disk drive's servo control processor that generates the control signal to the voice coil motor (VCM) actuator that controls the positioning of the read/write head. The processor uses S, Sand the head position error signal (PES) as inputs to run an adaptive RV feedforward (RVFF) algorithm. The adaptive RVFF algorithm takes the PES and sensor outputs Sand Sas inputs, mathematically determines the required correction to the sensor gain factors kand k, respectively, and then adjusts the gain factors kand kaccordingly. Each signal S, Sis then modified by its adjusted gain factor k, k, respectively. The difference in the modified S, Ssignals is the RVFF signal that is summed with the control signal to generate the RV-compensated control signal to the VCM actuator.

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Saratoga, CA, United States of America

Xiaotian Sun