Maxtor Corporation

Seagate Technology Incorporated

Yu Sun

Lin Guo

Don Brunnett

Xiaoping Hu

Yunfeng Li

Stan Shepherd

S Craig Smith

Yuan Chen

Xin Yang

Brian P Rigney

Stanley H Shepherd

Lloyd E Levy

Bruce A Liikanen

Richard M Ehrlich

Yanning Liu

Charles R Watt

Wei Guo

John Charles Purkett

Thomas O Melrose

John VanLaanen

John W Vanlaanen

Jason Adler

Mark Rice

Mark Heimbaugh

Jingbo Yu

David M Sigmond

Dwight Russell Kinney

Dave McMurtrey

Craig Smith

Matthew A O'Hara

David Jeppson

Todd Franks

Adrian E Cerda

Don Brunnet

Georgie Tan

Donald Brunett

XiaoPing Hu

Bill Flynn

Paul Yeagle

Pang L Tan

Examples of the present invention relate to reduction in acoustic noise by tuning seek characteristics of a servo controller, depending on a radial position of a head relative to a disk. The servo controller can provide compensation for acoustic resonance modes.

Radial position seek tuning for acoustic performance

Devices and methods for performing dynamic sampling of a back electromotive force (BEMF) measurement are provided. A device has hardware, including a voice coil motor (VCM) for receiving a VCM command signal and a correction circuit, for obtaining the VCM command signal and a coil voltage measurement from the hardware, where the correction circuit removes a transient voltage measurement due to a change in the VCM command signal from the coil voltage measurement and outputs an estimated BEMF measurement.

Methods and apparatuses for measuring VCM BEMF at a VCM control update rate

Methods and structure for switching heads on a multiple recording surface disk drive that uses bi-directional radial writing toward a zipper zone at a middle diameter. When switching from a first head to a second head, features and aspects hereof assure that the second head will not be positioned in the zipper zone of the corresponding second surface and hence will not lose track following servo synchronization and control. In one aspect, added buffer or guard tracks having valid servo information but no data are added on either side of the zipper zone to assure that under the worst-case misalignment of surfaces the second head will not be positioned in its corresponding zipper zone when switching from the first head.

Methods and structure for improved disk head switching to avoid zipper zones

Embodiments of the present invention reduce the written-in run-out in servo data written to a storage medium. A set of servo controllers are evaluated and the controller having the best expected performance among the set is selected and employed. One embodiment of the present invention is a servo controller configured to select and employ a controller having a least amount of expected written-in run-out among a set of controllers. Another embodiment of the present invention is a method comprising a step for applying a set of controllers; and selecting a controller from the set of controllers with a least expected amount of written-in run out. Another embodiment of the present invention is a system comprising a servo controller for employing and selecting a disk controller that has a least expected amount of written-in run-out among a set of controllers.

Controller selection to reduce written-in run-out

An apparatus and method for servo writing are disclosed. The method includes writing of first servo data to a medium, detecting a velocity integrated position of the first servo data, and writing second servo data in relation to the detected position of the first servo data.

Self-servo writing using staged patterning

In accordance with various embodiments, a rotatable member is mounted to a spindle hub so that initial servo data previously provided to the rotatable member are eccentrically offset with respect to a rotational center of the spindle hub. Compensation vales are determined to characterize said offset, after which final servo data are provided to the rotatable member in relation to the initial servo data and the determined compensation values. The final servo data are nominally concentric with the rotational center of the spindle hub.

Servo writing with offset compensation for prewritten reference

A magnetic storage system includes a disk, a head, an actuator, and a servo controller. The servo controller monitors a value, such as a position error signal (PES) sample value, a predicted PES sample value, and the like, that is based on servo information provided by the head. The servo controller provides a signal to inhibit writing by the head based on a comparison of the monitored value with a threshold, such as a write fault window (WFW), a PES plus Velocity (PPV) threshold, and the like. The servo controller sets the threshold to a first value based on at least one of an on-track track misregistration (TMR) value and a seek settle TMR value. When the servo controller determines that the head is subject to a vibration condition, the servo controller sets the threshold to a second value that is different from the first value.

Magnetic storage systems and methods with tighter write fault window to improve reliability

Embodiments of the present invention allow for controlling a microactuator based at least in part on an output of a temperature sensor. Also, embodiments of the present invention allow for adjusting a control of a microactuator so as to compensate for changes in a gain of the microactuator due to changes in temperature.

Microactuator control adjustment using temperature sensor measurements

Performing embedded runout correction for a track on a rotational data storage disk includes measuring written-in runout for the track, selecting a number of revolutions in response to the measured written-in runout of the track, calculating embedded correction values for the track for the selected number of revolutions of the rotational data storage disk, and storing the embedded correction values.

Embedded runout correction based on written-in runout measurement

A servo system for a hard disk drive comprising a first actuator, a second actuator, a head, and a disk on which is formed a plurality of tracks containing servo data. The servo system comprises a first stimulus, a second stimulus, and a calibration system. The first stimulus causes the first actuator to move the head to at least two calibration tracks on the disk. The second stimulus causes the second actuator to move the head relative to the at least two calibration tracks. The calibration system generates a calibration factor based on the second calibration signal and the movement of the second actuator relative to each of the at least two calibration tracks.

Micro actuator DC gain calibration scheme for HDD dual-stage actuator systems

Real-time correction of repeatable runout for multiple harmonic frequencies is provided by using convolution of a position error signal, or similar real-time signal, with an impulse response of a specific transfer function, such as the inverse of the disturbance transfer function. Multiple harmonic frequencies can be followed substantially simultaneously to achieve small position error and good tracking misregistration (TMR) performance. The impulse response can be obtained, calculated and stored off-line. The impulse response can be configured to substantially eliminate correction of one or more frequency or frequency ranges. Convolution can be done relatively quickly with proper arrangement of memory.

Convolution based multiple harmonic frequency repeatable runout compensation method and apparatus

In accordance with various embodiments, initial servo data are written to a storage medium as a series of radially overlapped spiral segments. Final servo data are thereafter written to the medium while concurrently servoing on said overlapped segments.

Servo writing using radially overlapped servo segments

The present invention is directed to a method and apparatus for moving off of a disk drive's crash stop in a consistent manner.

Method and apparatus for moving off of a disk drive's crash stop in a consistent manner

Methods of controlling seeking of a transducer that is adjacent to a rotatable disk in a disk drive are disclosed. The methods may include accelerating the transducer radially across the rotatable disk from an initial track on the rotatable disk toward a destination track on the rotatable disk, estimating a deceleration switching position/velocity point, estimating a maximum deceleration position/velocity point following the deceleration switching position/velocity point, and estimating a deceleration current required to decelerate the transducer from a non-zero velocity at the maximum deceleration position/velocity point to zero velocity at the destination track. The estimated deceleration current is compared to a maximum available deceleration current, and responsive to a determination that the current required to decelerate the transducer from the maximum deceleration point to the destination track exceeds the maximum available deceleration current, the estimated deceleration switching point is adjusted. Related disk drive apparatus are also disclosed.

Dynamically controlling seek profile in an acceleration tracking seek controller

A hard disk drive is disclosed comprising at least one disk rotatable about an axis, an actuator assembly moveable relative to the disk, a transducer positioned on the actuator assembly, an actuator signal line, a piezoelectric actuator element disposed on the actuator assembly and electrically interconnected to the actuator signal line, a processor, a sensor signal line and a piezoelectric sensor element for sensing a vibration. The piezoelectric sensor element is collocated with the piezoelectric actuator element and electrically interconnected to the processor by the sensor signal line. The piezoelectric actuator element is operable to move the at least one transducer relative to a surface of the disk. The piezoelectric sensor element is electrically isolated from the piezoelectric actuator element. A method for detecting a vibration in a hard disk drive actuator assembly is also disclosed.

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Fremont, CA, United States of America

Yu Sun