According to one embodiment, a disk device includes a magnetic disk, a magnetic head, a suspension, a ramp mechanism, a housing, and a screw. The suspension holds the magnetic head and moves between a load position and an unload position. The ramp mechanism includes a ramp member that holds the suspension at the unload position, and a cylindrical member with a through hole, being fixed to the ramp member. The housing includes a first support surface with a screw hole supporting the cylindrical member. The screw includes a screw head and a screw shaft fitted into the screw hole through the through hole. The screw holds the cylindrical member between the screw head and the first support surface. A contact area between the cylindrical member and the housing is set to larger than a contact area between the cylindrical member and the screw head.

A heat-assisted magnetic recording head is moved relative to a magnetic recording medium. The medium comprises a plurality of sectors. The sectors define a plurality of sector groups distributed around a circumference of the medium. The sectors of each sector group are written using different operational currents supplied to a laser diode of the head such that at least one sector from each sector group is written using one of the different operational currents. For each of the different operational currents, an average write performance metric is calculated for all sectors written at each of the different operational currents. A particular operational current of the different operational currents is determined that results in a best average write performance metric.

A circuit includes a light source, a sensor, and a switch. The sensor measures output of the light source and provides an electrical signal to a feedback loop that is indicative of the measured output of the light source. The switch is positioned in the feedback loop and is movable between a first position and a second position depending upon whether the feedback loop is operating in a first mode of operation or a second mode of operation. During the first mode of operation the output of the feedback loop adjusts at least one operating parameter of the light source responsive to the electrical signal. During the second mode of operation the output of the feedback loop does not adjust the at least one operating parameter of the light source responsive to the electrical signal.

According to one embodiment, a magnetic disk apparatus includes a magnetic head, a voice coil motor, a driving circuit, and a VCM resistance estimation unit. The magnetic head accesses a magnetic disk. The voice coil motor drives the magnetic head over the magnetic disk. The driving circuit applies a VCM current to the voice coil motor. The VCM resistance estimation unit estimates a VCM resistance in the voice coil motor based on the saturated VCM current and a velocity of the magnetic head.

A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a fly height actuator configured to control a fly height of the head over the disk. A plurality of host read commands are received from a host, and a performance metric associated with accessing the disk to execute the host read commands is measured. When the performance metric indicates the data storage device is operating with a performance margin, the fly height actuator is controlled to increase the fly height of the head over the disk, wherein the performance metric consists of at least one of a throughput of the host read commands and a power consumption of the data storage device.

A data storage device comprising a head actuated over a disk comprising a plurality of tracks. The head is positioned over a target track, and a sampled position error signal (PES) is generated representing a position of the head relative to the target track. The sampled PES is filtered with a servo compensator to generate a sampled control signal, and the sampled control signal is upsampled to generate an upsampled control signal. The sampled PES is upsampled to generate an upsampled PES, and the upsampled PES is processed to generate compensation values. The upsampled control signal is combined with the compensation values to generate a compensated control signal, and the position of the head over the target track is adjusted based on the compensated control signal.

An apparatus comprises a slider configured for heat-assisted magnetic coupled to a controller. The slider comprises a writer, a heater, a near-field transducer, and an optical waveguide for communicating light from a laser diode to the near-field transducer. The controller is configured to set a target pre-write clearance of the slider prior to performing a write operation, set a target write clearance of the slider for performing the write operation, and determine a difference between the target pre-write and write clearances to define a target pre-write clearance offset. The controller is also configured to measure, for a plurality of different target pre-write clearance offsets, a writability metric for the slider while sweeping a laser diode current, and adjust the target pre-write clearance offset so that the writability metric reaches a predetermined threshold. The controller is further configured to perform subsequent write operations using the adjusted target pre-write clearance offset.

A storage device disclosed herein includes a transducer head with a proximity sensor that generates head-disc proximity signals, a digitizer configured to convert the analog proximity signals from the proximity sensor to digitized sample data, a discrete wavelet transformation (DWT) module configured to analyze the digitized sample data by performing an enhanced DWT on the digitized sample data to generate DWT coefficients, and a modal filter configured to determine dominant head-disc interference (HDI) modes for a transducer head by analyzing the DWT coefficients.

According to one embodiment, a position detecting device includes a detecting portion which periodically detects a plurality of pieces of information generated in accordance with positional information divided into upper digits and lower digits. The upper digits are further divided into a plurality of pieces of upper digit information equal to the number of the period. The pieces of the upper digit information are obtained in a predetermined order. The lower digits are obtained simultaneously with any one of the pieces of the upper digit information. The positional information is divided so that the number of values, which are obtainable in one piece of the upper digit information provided by dividing the upper digits, and a division number of the upper digits are coprime.

A driver device coupled to a winding of an electro-mechanical actuator includes: a power stage driving the winding in a discontinuous mode by alternating conduction on-phases to off-phases, and a sensor circuit sensing a voltage across the winding in an off-phase, wherein, during such an off-phase the voltage across the winding includes a residual voltage which decays to zero. The power stage drives the winding from an on-phase to an off-phase by applying to the winding a reverse current pulse to invert the direction of flow of the current through the winding and produce an oscillation of the residual voltage, whereby the residual voltage includes a zero-crossing point after the current through the winding is exhausted. The sensor circuit senses the voltage across the winding at this zero-crossing point, whereby the voltage sensed across the winding at the zero-crossing point is indicative of the back electromotive force of the winding.