Seagate Technology Incorporated

Ryan Todd Lyle

Jeffrey Don Andress

James W Dulaney

Scott Edward Ryun

Raye Abdoulie Sosseh

Paul William Burnett

David Charles Waugh

Brian Robert Pollock

Philip Ray Woods

Matthew Glenn Duvall

Richard Arthur Herr

James Wilford DuLaney

Wonbo Shim

Ryan Thomas Herbison

Narrow band dwell occurs when air bearings corresponding to a set of read and/or write heads within a hard disc drive remain within a fixed narrow band of one or more storage platters for an extended period of time. The air bearings displace lubricant on the storage platters and may redeposit the lubricant as droplets on the platters. The presently disclosure technology is directed to monitoring a hard disc drive for narrow band dwell, and in some implementations, implementing operations to mitigate narrow band dwell. More specifically, the presently disclosure technology may detect an overflying air-bearing slider position, apply a lubrication film displacement formula to a narrow band of the storage platter, apply a lubrication film reflow formula to one or more other narrow bands of the storage platter, and track lubrication film thickness over time in each of the narrow bands of the storage platter.

Narrow band dwell monitoring

Method and apparatus for accelerating a multi-phase motor having a rotatable rotor are disclosed. A first commutation state in which the rotor resides is identified, after which a Proportional, Integral and Derivative (PID) control routine is executed for closed loop control of an acceleration of the rotor from a stopped position to an intermediate velocity, after which back electromotive force (Bemf) commutation is used to control the motor. The PID control routine utilizes a loop gain value optimized through voltage feedback indicative of a response of windings of the rotor to an application of a drive current across the windings. Based on the voltage feedback a controller programmed with the PID control routine provides an updated commanded current for each successive commutation state of the motor for use by a motor driver circuitry, which drives the motor through each commutation state until attainment of the intermediate velocity.

Closed loop acceleration control for a data storage device motor

Method and apparatus for compensating for a decrease in the torque constant of an actuator motor in a data storage device. An actuator supports the head adjacent a data recording surface on which a plurality of tracks are defined. A servo circuit outputs current to the actuator motor to carry out a seek to move the head from an initial track to a destination track in accordance with a velocity profile having a nominal deceleration trajectory along which the head is decelerated to reach the destination track. The servo circuit operates to adjust an initial value of gain to a second value in response to a selected parameter, and scales the nominal deceleration trajectory to a derated deceleration trajectory in relation to the second value of the gain. The derated deceleration trajectory is preferably selected in relation to the difference between the second value of gain and a predetermined threshold.

Motor torque constant variation compensation

Method and apparatus for performing a seek operation to move a data transducing head from an initial track to a destination track on a rotatable recording surface. A servo control circuit operates to sweep the head across the recording surface. Servo data from an intermediary track are transduced to obtain a detected angular position value for the head with respect to the recording surface. When the detected angular position value differs from a predicted angular position value for the head, the servo control circuit initiates an index qualification routine at the conclusion of the seek. The qualification routine involves transducing the servo data from the destination track to verify the accuracy of the predicted angular position value. In this way, the effects of spurious (false) index signals obtained from the servo data transduced during the seek operation are minimized, and unnecessary reinitializations of the servo control circuit are avoided.

Adaptive index reference position qualification

Method and apparatus for reducing and dispersing wear to the surface of a rotatable disc in a disc drive using an adaptive dither process. The disc drive includes an actuator assembly that is secured in a parked position by a latch when not in use. The method includes determining an open latch current required to open the latch as the actuator assembly is moved from the parked position to a position over a user data storage portion of the disc. A dither current is subsequently applied to the actuator assembly to induce a reciprocating lateral displacement of the actuator assembly when the actuator assembly is secured in the parked position, wherein the maximum amplitude of the dither current is selected to be less than the open latch current.

Wear reduction of a disc surface using an adaptive dither process

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Oklahoma City, OK, United States of America

Ryan Todd Lyle