Seagate Technology Incorporated

WeiSung Lee

KianKeong Ooi

ShuangQuan Min

Xiong Liu

MingZhong Ding

YangQuan Chen

BengWee Quak

WingKong Chiang

Qiang Bi

ChoonKiat Lim

Kian Keong Ooi

Ricky Wei Watt Yeo

KianSoon Yeo

JiaHong Shu

TzeMing Jimmy Pang

EikFun Khor

KianKeon Ooi

Various embodiments of the present invention are generally directed to protecting a device from damage due to an impact event at the conclusion of a free fall condition through the use of a biasing signal that maintains a retention force until the impact event is completed.

Impact protection for a retractable control object

A location within a cycle is determined by reading a portion of a cyclic bit sequence, the bit sequence containing several interspersed bit-group sets that each contain a plurality of series that each consist of several consecutively-placed identical bit-groups. On a data surface in a disc drive, each bit group can be stored and accessed in unused bits of each servo sector's digital portion.

Determining a location based on a cyclic bit sequence containing consecutively-placed identical bit-groups

Track closure errors written into servo sectors of an information track of a disc of a disc drive are resolved from a position control signal generated by a servo control circuit of a data storage device by steps comprising: determining a value for the track closure error from a position error signal, establishing a track closure profile based on the value of the track closure error, and injecting the track profile into the servo control circuit as a feed forward compensation input for the position error signal to resolve the track closure error from the position control signal.

Track closure error cancellation for a disc drive

Written-in runout due to vibration of the cage of a spindle motor of a disc drive is detected by identifying an initial cage frequency value of the motor. A written-in magnitude of successive servo burst closures, D(n ), is read over a plurality of tracks, and a maximum servo burst closure D(n ) is identified from the plurality of read servo bursts. A magnitude of the cage frequency at a servo sector n is calculated based on a difference between the read magnitudes of the servo burst closures at servo sectors n and n , and a phase of the cage frequency is calculated based on the magnitude of the written-in cage frequency at servo sector n . The profile, in the form of cage frequency, maximum servo burst closure magnitude, and initial phase, is stored in a memory or table for each of a plurality of radial zones of tracks. The profile is combined with a position error signal and applied to the controller in a feed forward scheme to adjust the position of the head based on the written-in runout.

Identification and cancellation of cage frequency in a hard disc drive

Steps for isolating and correcting total written-in repeatable run-out error written into servo sectors of a disc drive include, determining a total repeatable run-out error value for each servo sector, isolating a repeatable error value component of the total written-in repeatable run-out error value for each servo sector, removing the repeatable error value component from total written-in repeatable run-out error value to provide a non-repeatable error value component of the total written-in repeatable run-out error value for each servo sector, providing both the repeatable and non-repeatable error value components to a processor for generation of compensation signals, and applying the compensation signals into a servo control circuit of control loop of the disc drive using compensation circuits to compensate for each component of the total written-in repeatable run-out error.

Repeatable run-out error compensation method for a disc drive

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Singapore, Singapore

WeiSung Lee