Abstract: For unlatching a head within a data storage device, such as a HDD (hard disc drive), a VCM (voice coil motor) amplifier with a switch is used for applying at least one cycle of an acceleration current pulse to a voice coil motor (VCM) for unlatching the head during an acceleration time zone. An analog to digital converter samples a characteristic of the VCM for indicating a speed of the head during the acceleration time zone. An unlatch controller terminates the acceleration time zone when the speed of the head is higher than a threshold speed, for more stable operation of the head but with guarantee of unlatching, regardless of the latch force within the HDD.

Abstract: An apparatus, medium, and method to control a disk drive, and in particular, an apparatus, medium, and method controlling a disk drive to perform a seek mode at an optimum state with respect to an operational temperature. A seek servo control method considering temperature change in controlling a disk drive may includes determining a seek time considering a given seek length and operational temperature change in a seek mode, and generating position, velocity, and acceleration trajectories to move a transducer according to the determined seek time.

Abstract: A method and apparatus to compensate for a difference between an actual torque constant and a modeling torque constant used for servo design in a disc drive. The method has operations of: performing predetermined test seeks with respect to test seek positions into which a disc is divided; obtaining torque compensation constants from the test seeks; storing the torque compensation constants in a torque compensation constant table; and compensating for a gain of a seek control loop at a position where a seek is performed in a seek mode, using the torque compensation constants stored in the torque compensation constant table.

Abstract: A seek servo control method and device for a disk drive device for performing seek servo control according to a variation in a power supply voltage for the disk drive. The seek servo control method includes: detecting a supply voltage for the disk drive; and adjusting a seek time according to a track seek length based on the detected supply voltage.

Abstract: A hard disc drive (HDD) data read control apparatus, medium, and method reading data from a disc having non-uniform track-to-track spacing. The data read control method of the HDD, in which data is read from a disc including non-uniform track-to-track spacing, includes seeking a target track by adopting an off track amount applied to a previously followed track, and reading the data while following the sought target track. Accordingly, production yield can be increased by making failure processing unnecessary even if a track-to-track spacing of a HDD is non-uniform.

Abstract: A method, medium, and apparatus for controlling a spindle motor of a disk drive. Particularly provided is a method, medium, and apparatus changing a current gain of a spindle motor driver according to the operating environment of the spindle motor. The method of controlling the spindle motor, using the current gain change of the spindle motor driver, includes monitoring a spindle drive control signal indicating the operating environment of the spindle motor and changing a current gain of the spindle motor driver based on the indicated operating environment.

Abstract: A method, medium, and apparatus controlling a hard disk drive, and more particularly, a method, medium, and apparatus controlling a track seek of a hard disk drive, where the hard disk drive compensates for a gain distortion and a phase delay caused by a notch filter and a VCM driver using a sinewave acceleration trajectory. According to the method of controlling a track seek of a hard disk drive, an ideal sinewave for obtaining a position y*(n), a velocity v*(n), and an acceleration a*(n), according to a sinewave acceleration trajectory, and a sinewave indicating a gain distortion and a phase delay may be integrated and a VCM driving current u(n) can be generated by the integrated sinewave for compensating for gain distortion and phase delay, compensating for a value C(j2?f) of the gain distortion and the phase delay caused by the notch filter and the VCM driver.

Abstract: A hard disk drive that utilizes a plurality of integrated gain compensation values to correct a non-linear position error signal (PES) function of the drive. The gain compensation values are generated, integrated and stored during an initial burn-in process of the drive. The PES is used in a servo loop to position a head relative to a track of a disk. The PES may have a non-linear function such that the signal is not representative of the actual position of the head. The integrated gain compensation values are used to correct the non-linear function so that the PES more accurately reflects the position of the head relative to the track.

Abstract: 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.

Abstract: A method, medium, and apparatus controlling a hard disk drive, and particularly, embodiments include methods, media, and apparatuses compensating for torque variations with respect to temperature variations in a seek servo operation, compensating for differences between modeling torque constants, used for servo designing, and actual torque constants. The method includes controlling gain of a seek control loop to vary depending on a torque constant temperature compensation value corresponding to a measured temperature of the hard disk drive, the seek control loop generating a seek driving current to be applied to a voice coil in the seek mode.

Abstract: 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.

Abstract: 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.

Abstract: A method of testing quality of a servo burst signal recorded on a hard disk drive and a recording medium adapted therefor, the hard disk drive including a plurality of sectors within one track and the burst signals for servo control recorded radially on each sector. The method includes: detecting peak positions at a radial position in which amplitudes of the recorded burst signals peak respectively on each track; comparing the detected peak positions of the burst signals on each track; detecting peak position error count, the peak position error count being a number of tracks in which offset of the detected peak positions exceed an offset limit within a predetermined number of tracks; and if the peak position error count exceeds the offset limit, determining a write quality of the servo burst signal to be low. A servo burst signal recorded with uniform intensity and a servo burst signal recorded with shift from normal position can be detected.

Abstract: A method and apparatus to compensate for a difference between an actual torque constant and a modeling torque constant used for servo design in a disc drive. The method has operations of: performing predetermined test seeks with respect to test seek positions into which a disc is divided; obtaining torque compensation constants from the test seeks; storing the torque compensation constants in a torque compensation constant table; and compensating for a gain of a seek control loop at a position where a seek is performed in a seek mode, using the torque compensation constants stored in the torque compensation constant table.

Abstract: 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.

Abstract: For unlatching a head within a data storage device, such as a HDD (hard disc drive), a VCM (voice coil motor) amplifier with a switch is used for applying at least one cycle of an acceleration current pulse to a voice coil motor (VCM) for unlatching the head during an acceleration time zone. An analog to digital converter samples a characteristic of the VCM for indicating a speed of the head during the acceleration time zone. An unlatch controller terminates the acceleration time zone when the speed of the head is higher than a threshold speed, for more stable operation of the head but with guarantee of unlatching, regardless of the latch force within the HDD.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.