Seagate Technology Incorporated

Nathaniel Boyd Wilson

Reed David Hanson

Timothy Francis Ellis

John Christopher Morris

Lealon Ray McKenzie

Thomas C Zirps

Stuart Kevin Francis

D Brent Douglas

Roy Lynn Wood

Jason Dale Gregg

Brent Jay Harmer

Dustin Mark Cvancara

Brian Robert Pollock

Mark Larry Birtzer

Arthur J Clark

A processor is configured to perform a method () including a step of deriving lateral offset indicators () from a longitudinal position measurement (). Improved seek cost indicators () are generated, some or all based on a respective lateral offset indicator (). Then a target destination is selected using at least one of the improved seek cost indicators ().

Selecting a target destination using seek cost indicators based on longitudinal position

Method and apparatus for certifying servo sectors on recording surfaces of a disc stack of a data storage device to promote servo sector alignment among the various recording surfaces. A reference servo sector pattern is written to a first recording surface, the reference pattern comprising a plurality of angularly spaced apart servo sectors. Multiple interleaved sets of servo sector patterns are written to each of the remaining recording surfaces, each interleaved pattern respectively comprising a plurality of angularly spaced apart servo sectors. A selected interleaved pattern is identified from each of the remaining surfaces that provides a desired alignment with the reference servo sector pattern, and the non-selected servo sector patterns are overwritten. The servo patterns can be written to the discs prior to installation using a multiple disc writing (MDW) station, or after installation of the discs into the data storage device using a servo track writing (STW) station.

Writing multiple servo sector patterns to improve servo sector alignment on multiple surfaces

In a data handling system having a radially-dependent track incongruity between data surfaces, at least some tracks are logically mapped so that tracks on different data surfaces correspond with one another. The correspondence is defined by the mapping so as to shorten an average headswitch seek. For example, a logical track mapping of first and second non-coaxial track sets can be defined so as to optimize a headswitch seek within each of many intermediate logical cylinders identified in the mapping.

Logical mapping for improved head switching between corresponding tracks in a data handling device

An apparatus and method for tracking radially-dependent repeatable run-out in a disc drive having a servo loop for positioning a head over a rotating disc is provided. The disc includes multiple tracks. Radially-dependent repeatable run-out control components for at least a subset of the multiple tracks are first determined. Data representative of the radially-dependent repeatable run-out control components for the subset of the multiple tracks is then stored. The stored data representative of the radially-dependent repeatable run-out control components is retrieved before settling on the target track, and subsequently used to follow the selected track.

Method and apparatus for tracking radially-dependent repeatable run-out

An apparatus and method of tracking repeatable runout in a disc drive servo loop is provided in which a feedforward signal having harmonic components that are updated at a sample rate that is a fraction of a servo sector sample rate is employed during track following.

Fractional-rate feedforward RRO compensator

Problems inherent in guiding a sensor via a piecewise-linear lateral parametric profile are generally avoided using at least one broadly curved, generally lateral profile (). A sensor is configured to move in a nominally longitudinal direction relative to a frame of reference (). A position scale is defined in a generally lateral direction relative to the longitudinal motion (). Each broadly curved lateral profile is defined in terms of its corresponding position scale, the scale(s) and the profile(s) both being part of a parametric model that is available for use in guiding the sensor ().

Guiding a sensor using a broadly-curved lateral profile

An apparatus and method for compensating for variation in sample rate in a disc drive having a rotating disc and a head that is positioned over the rotating disc is provided. The disc includes at least one track that has multiple consecutive sectors. A sample rate value between timing marks of each pair of consecutive sectors of the multiple consecutive sectors is computed to obtain a sequence of sample rate values. A sequence of timing error values is computed as a function of the sequence of sample rate values and a nominal sample rate value. Data related to the sequence of timing error values is utilized to compensate for variation in sample rate values.

Compensation for timing variation in disc drives employing servo tracking systems

An apparatus and method for minimizing the effects of rotational vibration upon a disc drive having a base deck supporting a rotatable disc and an actuator having a moveable data head. A fixed head is supported over the disc at a predetermined radius and transduces a circumferentially extending frequency pattern written to the disc at a constant frequency to generate a readback signal. A frequency modulation (FM) demodulator generates a rotational velocity signal indicative of application of rotational vibration to the base deck in relation to changes in frequency of the readback signal. A servo circuit controllably positions the moveable data head in response to the rotational velocity signal and servo information readback by the moveable data head. The servo circuit interrupts a data transfer operation between the moveable data head and a host device when a magnitude of the rotational velocity signal exceeds a predetermined threshold. The circumferentially extending frequency pattern is preferably used to clock the writing of the servo information during disc drive manufacturing.

Rotational vibration compensation using a fixed head and a constant frequency pattern

An apparatus and method for minimizing the effects of rotational vibration upon a disc drive having first and second heads supported adjacent first and second disc recording surfaces, respectively. A frequency modulation (FM) demodulator generates a rotational velocity signal indicative of application of rotational vibration to the base deck in relation to changes in frequency of a readback signal generated from a circumferentially extending frequency pattern written to the first disc recording surface at a constant frequency. A servo circuit controllably positions the first and second heads in response to servo information stored on the second disc recording surface and the rotational velocity signal from the FM demodulator. The servo circuit further interrupts a data transfer operation between the second disc recording surface and a host device when a magnitude of the rotational velocity signal exceeds a predetermined threshold.

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Edmond, OK, United States of America

Nathaniel Boyd Wilson