Samsung Electronics Co., Ltd.

Sang Hoon Chu

Jun Seok Shim

Soo Il Choi

Young-Hoon Kim

Kang Seok Lee

Hyung Jai Lee

Seong-Woo Kang

Yun-Sik Han

Tung Thanh Nguyen

Dong-Ho Oh

Tae Yeon Hwang

Seong Hwon Yu

Seong Hwan Yu

Dong Jun Lee

Dong-Jun Lee

Jong Yun Yun

Dongman Kim

Chang Ik Kang

Young Hoon Kim

YoungDug Jung

Yeong Kyun (John) Lee

Won Goo Kim

Yong Gwon Lee

Ju Il Lee

Cheol Hoon Park

Gyu Tack Kim

Gyu Taek Kim

A hard disk drive using an increase in servo address mark delays to create a touchdown flag in response to a slider making contact with a rotating disk surface while accessing a track. This may be used particularly when the track being accessed is located away from the Inside Diameter (ID). The hard disk drive may further use resistive heater electrical readings to determine the touchdown flag for track locations near the ID. The hard disk drive may be calibrated during manufacture and/or may be recalibrated in the field with this method. The calibrated hard disk drive is a product of this method. The method may be used during normal access operations and/or may be embodied as a program system residing in computer readable memory for instructing a computer operating the hard disk drive, where the computer and/or the memory may or may not be included in the hard disk drive.

Method and apparatus for estimating touchdown of a slider in a hard disk drive

A hard disk drive with a controller that determines a position error signal gain. The position error signal gain is determined from a total servo loop gain and a function that is defined by a slope of a line of A and B servo bits measured at N off-track positions. The function determines an actual plant gain and thus provides a more accurate position error signal gain.

Method for estimating position error gain for hard disk drives

The invention applies to servo controllers for at least the voice coil motor of a hard disk drive. Today, many control algorithms require 80 to 90 percent of the sampling period to complete their calculation of the next control, making computation time delay no longer negligible. The invention accommodates the transport delay, such as computation time delay, into the state estimator and into the whole control system. Experimental results using a commercial hard drive, as well as simulation results, show that the invention's method effectively improves the hard disk drive control system stability by increasing the phase margin and gain margin. The invention includes the method of operating the servo-controller, as well as the apparatus implementing that method. The invention also includes hard disk drives containing servo-controllers implementing the method, and program systems residing in accessibly coupled memory to a computer within the servo controller implementing the method.

Servo controller method and apparatus for high tracks per inch hard disk drives using a delay accomodating state estimator

A hard disk drive that includes a voice coil motor and a micro-actuator. The micro-actuator is controlled by a servo that utilizes a micro-actuator controller and a corresponding micro-actuator transfer function. The servo enters a mode to self-determine at least one transfer function coefficient of the micro-actuator controller.

Online identification of secondary actuator transfer function via system decoupling in multiple-stage actuator servo systems in disk drives

RRO corrector function is formulated to partition the contribution of micro-actuator control from the other voice coil assembly contributions. Single stage actuation is supported by zeroing the micro-actuator control queue, otherwise multi-stage actuation is supported. The multi-stage actuation may include dual stage actuation and in some embodiments triple stage actuation. Triple stage further partitions RRO corrector function for the contribution of the second micro-actuator. Method of initializing an assembled hard disk drive creates hard disk drive as product, using the written-in parameter list for track on the disk surface to recreate the RRO corrector as RRO corrector filter using queues updated by NRRO corrector.

Method and apparatus for single written-in Repeatable Run-Out correction function used in multi-stage actuation control of hard disk drive

The present invention is a method and apparatus for positioning a read/write head in a hard disk drive. The method comprises providing a disk having a at least one side with a plurality of tracks, where each of the tracks has a servo field with servo bits. The servo bits are read to provide a position signal for positioning a read/write head. The method determines a difference in position between an initial and a subsequent position of the read/write head on a track, where the subsequent location occurs after the read/write head has moved one revolution from the initial position on the track. The initial and subsequent positions are offset laterally. The method generates a compensation signal based on the initial position, the subsequent position and the difference. The position signal and the compensation signal are combined to provide a compensated position signal for positioning the read/write head. Various embodiments are described.

Method and apparatus for providing positional information on a disk

A hard disk drive that redefines a notch filter of the drive. The update process may include initially disabling all notch filters and inducing a seek operation of the disk drive heads. A position error signal is read during a settling time of the seek operation and processed to determine the frequency of the signal. The frequency is selected as a resonant frequency if the error signal magnitude exceeds a threshold value. The notch filter is then redefined in accordance with the selected resonant frequency. The controller may also perform a routine to determine whether the resonant frequency is above or below a Nyquist frequency. Unlike prior art techniques, the method disclosed can obtain the resonant frequency without sweeping the excitation signal of the disk drive voice coil motor.

Method for resonance identification in hard disk drives

The invention provides magnetic disks with the ability for consecutive tracks to be read or written continuously, removing the traversal of the gap between tracks which degrades bandwidth delivery performance. The invention includes a disk surface formatted with tracks, and sectors within these tracks, which vary in radius. The ending radius of a sector differs significantly from its starting radius. The ending radius of the last sector of one track is very close to the starting radius of its successor track, providing a spiral arrangement of tracks, each possessing a fixed number of sectors, and supporting continuous accessing of successive tracks.

Method and apparatus providing spiral servo control for skewless read/writes in a hard disk drive

The present disclosure relates to a system for detecting a plurality of defect types on the surface of a disk in a hard disk drive. In particular, the disclosure relates to utilizing information obtained from a plurality of servo bits to determine if a sector contains a physical defect. Where such a defect is found, the sector's write gate is disabled and its burst signal data is ignored for track following purposes. In addition, large changes in PES are used to identify closure spike defects. Such defects are managed by providing a compensation signal to the read value of the PES to improve track following. Finally, high PES values are used to signal a third defect type where no other signs of defect are present. In such case, the sector is mapped as defective, but the burst signals continue to be used for track following purposes.

Servo defect management scheme in hard disk drives

A method, apparatus and computer program for performing a servo seek according to a voltage-constrained sinusoidal acceleration trajectory. In one embodiment, the apparatus comprises a hard disk drive which has a disk with a surface, spin motor, transducer, and an actuator arm to move a transducer across the surface of the disk. The apparatus further includes a controller that controls the actuator arm and to perform a seek having a length. The actuator arm moves the transducer across the surface of the disk with an essentially sinusoidal acceleration trajectory using a substantially constant voltage. In another embodiment, the substantially constant voltage is based on the maximum voltage from a power supply.

Voltage-constrained sinusoidal seek servo in hard disk drives

An apparatus, method and computer program product for a hard disk drive defect detection system. In one embodiment, a method of detecting defects on the surface of a disk having a plurality of tracks is recited. The method comprises reading, one or more times, the servo bits for a plurality of sectors and determining a burst measure for at least one sector, where the burst measure is a function of the burst signals for the sector. This method further comprises determining a reference value, where the reference value is a function of the burst signals of the plurality of sectors, and comparing the burst measure of at least one sector to the reference value to identify a potential defect. In one embodiment, a sector is mapped as defective where its burst measure differs from the reference value by at least 5 percent.

Method and apparatus to detect and manage servo sectors with defect on servo pattern area in hard disk drives

A method, apparatus, and computer program product for a hard disk drive servomechanism. In one embodiment, the apparatus comprises a disk which has a surface, a spindle motor that rotates the disk, a transducer which can write information onto the disk and read information from the disk, and an actuator arm that can move the transducer across the surface of the disk. The apparatus further includes a controller. The controller can determine a seek length from a first track to a second track, determine a seek time based on the seek length, scale the seek time in response to a velocity error between a calculated velocity and a design velocity for the seek length, and control the actuator arm to move the transducer across the disk surface from the first track to the second track using an acceleration trajectory.

Seek trajectory adaptation in sinusoidal seek servo hard disk drives

A method for writing and reading data in a hard disk drive and compensating for an offset between a write element and a read element of a head. The method determines an offset time by determining the difference between a desired sync byte position and an actual sync byte position located between a preamble and a data sector of the disk. The difference corresponds to the offset between the read and write elements. The offset time is subtracted from the normal time for enabling the read gate of a disk drive pre-amplifier.

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Santa Clara, CA, United States of America

Sang Hoon Chu