Abstract: A magnetic storage medium comprises a plurality of discrete magnetic elements and first and second adjoining servo sectors. Each of the servo sectors comprises first and second rows of the discrete magnetic elements extending in a track direction. The second row of the discrete magnetic elements are stacked relative to the discrete magnetic elements of the first row in a cross-track direction that is perpendicular to the track direction. The discrete magnetic elements of the first servo sector are staggered in the cross-track direction relative to the discrete magnetic elements of the second servo sector.

Abstract: A magnetic storage medium comprises a plurality of discrete magnetic elements and first and second adjoining servo sectors. Each of the servo sectors comprises first and second rows of the discrete magnetic elements extending in a track direction. The second row of the discrete magnetic elements are stacked relative to the discrete magnetic elements of the first row in a cross-track direction that is perpendicular to the track direction. The discrete magnetic elements of the first servo sector are staggered in the cross-track direction relative to the discrete magnetic elements of the second servo sector.

Abstract: A recordable magnetic media includes a servo pattern having a plurality of adjacent alternating magnetic and nonmagnetic material stripes. At least some of the magnetic material stripes have magnetic transitions that define encoded data.

Abstract: A patterned recording media comprises a segment and a null pattern formed in the segment. The segment comprises first and second rows of discrete magnetic elements separated by a non-magnetic material, and a row of non-magnetic material positioned between the first and second rows. The null pattern comprises consecutive groups of the discrete magnetic elements in the first and second rows of the segment. Each group in the first row has a magnetic polarity that is opposite the magnetic polarity of adjoining groups in the first row. Each group in the second row has a magnetic polarity that is opposite the magnetic polarity of adjoining groups in the second row.

Abstract: A patterned recording media comprises a segment and a null pattern formed in the segment. The segment comprises first and second rows of discrete magnetic elements separated by a non-magnetic material, and a row of non-magnetic material positioned between the first and second rows. The null pattern comprises consecutive groups of the discrete magnetic elements in the first and second rows of the segment. Each group in the first row has a magnetic polarity that is opposite the magnetic polarity of adjoining groups in the first row. Each group in the second row has a magnetic polarity that is opposite the magnetic polarity of adjoining groups in the second row.

Abstract: A high bandwidth, large stroke spin-stand for testing components of a disc drive includes a coarse positioning stage and a rotary micropositioning stage. The spin-stand is capable of positioning a transducer head relative to the data storage disc based on one or both of: (1) an angular position of a rotary actuator arm in the rotary micropositioning stage; and (2) servo data read from the data storage disc. The angular position of the rotary actuator arm is detected by an encoder. In one embodiment, position adjustments are based on the detected angular position. In another embodiment, position adjustments are based on servo data read from the data storage disc, but are also conditional on angular position being consistent with the servo data. In yet another embodiment, both angular position and servo data from a track are linearized to generate PES adjustment parameters that are recorded on the data storage disc to redefine the track as more circular or to linearize the PES.

Abstract: The present invention relates to repeatable runout (RRO) compensation of servo control systems that can be used in disc drives or spin-stands. The RRO relates to eccentricity between servo tracks, which were written onto a disc prior to the installation of the disc into the disc drive or spin-stand, and an axis of rotation of the disc. The present invention compensates the servo control loop by canceling the RRO and controlling a head to follow virtual tracks which are eccentric to the data tracks defined by the servo tracks and concentric with the axis of rotation of the disc.

Abstract: A method for thermally writing a magnetic servo pattern on a magnetic disc medium prior to assembling the medium in a disc drive is provided in which the medium is first magnetized in a uniform magnetization direction. A plurality of magnetic domains are then thermally written on the medium, one magnetic domain at a time, by individually heating each magnetic domain with a light beam while exposing the magnetic domain to a magnetic field. The magnetic field has an orientation that is opposite to the uniform magnetization direction. The light beam forms an illumination pattern on the medium having a shape that at least partially defines a boundary of each magnetic domain.

Abstract: A data storage system includes a data storage disc for storing magnetically encoded data and servo information. The data storage disc includes a data layer adapted to be magnetically encoded with data to be written to the data storage disc, and a servo information layer formed beneath the data layer and having magnetic servo pits formed therein to provide servo information. The magnetic servo pits are positioned in portions of the servo information layer which are at least partially directly beneath magnetically encoded data regions on the data layer such that a data head can read both magnetically stored data and servo information from the disc at substantially the same time. A method of fabricating a magnetic data disc is also disclosed.

Abstract: A method for thermally writing a magnetic servo pattern on a magnetic disc medium prior to assembling the medium in a disc drive is provided in which the medium is first magnetized in a uniform magnetization direction. A plurality of magnetic domains are then thermally written on the medium, one magnetic domain at a time, by individually heating each magnetic domain with a light beam while exposing the magnetic domain to a magnetic field. The magnetic field has an orientation that is opposite to the uniform magnetization direction. The light beam forms an illumination pattern on the medium having a shape that at least partially defines a boundary of each magnetic domain.

Abstract: A method and apparatus are provided for testing a head to be used in a disc drive. The method is performed in a spin-stand and includes steps of positioning a head over a radial position on a disc, reading test data from a track at the radial position, reading servo data from the track, and using the servo data to position the head at a desired location within the track. The apparatus for practicing this method includes a disc capable of spinning, a positioning system capable of establishing a position for a head relative to the disc, a servo circuit capable of converting a servo signal into a position value, and a feedback circuit capable of controlling the positioning system based on the position value.

Abstract: A method and apparatus are provided for testing a microactuator that forms part of a suspension assembly in a disc drive. The method and apparatus test the microactuator before placing the suspension assembly in a disc drive. In the invention, the head is positioned over a track on a disc based in part on servo information read from the disc. At least one input signal is then applied to at last one microactuator on the suspension assembly. Servo information is then read from the disc to determine a change in the position of the head. By comparing the change in the position of the head to the input signal applied to the microactuator, a performance characteristic of a microactuator can be determined.

Abstract: A magnetic medium comprises a magnetic disc having a read surface that has a plurality of tracks, at least some having servo sectors. The servo sectors comprise a plurality of magnetic irregularities, such as pits or regions of reduced magnetic coercivity, arranged in a servo pattern along the servo sector at a servo frequency. A magnetic pattern is recorded in the disc along the servo sector at a high carrier frequency. A process for manufacturing the servo pattern and for recovering servo data from the servo pattern are also described.

Abstract: A high bandwidth, large stroke spin-stand for testing components of a disc drive includes a coarse positioning stage and a rotary micropositioning stage. The spin-stand is capable of positioning a transducer head relative to the data storage disc based on one or both of: (1) an angular position of a rotary actuator arm in the rotary micropositioning stage; and (2) servo data read from the data storage disc. The angular position of the rotary actuator arm is detected by an encoder. In one embodiment, position adjustments are based on the detected angular position. In another embodiment, position adjustments are based on servo data read from the data storage disc, but are also conditional on angular position being consistent with the servo data. In yet another embodiment, both angular position and servo data from a track are linearized to generate PES adjustment parameters that are recorded on the data storage disc to redefine the track as more circular or to linearize the PES.

Abstract: A method and apparatus for thermally writing a magnetic servo pattern on a magnetic disc medium prior to assembling the medium in a disc drive are provided in which the medium is first magnetized in a uniform magnetization direction. A plurality of magnetic domains are then thermally written on the medium, one magnetic domain at a time, by individually heating each magnetic domain with a light beam while exposing the magnetic domain to a magnetic field. The magnetic field has an orientation that is opposite to the uniform magnetization direction. The light beam forms an illumination pattern on the medium having a shape that at least partially defines a boundary of each magnetic domain.

Abstract: A method of refreshing magnetization of a servo pattern in a magnetic medium within a disc drive is provided, wherein the servo pattern is at least partially defined by physical features of the medium. The method includes reading servo information through a transducer in the disc drive from a first portion of the servo pattern. The transducer is positioned at a radial position relative to the medium based on the servo information. The magnetization of a second portion of the servo pattern is then refreshed at the radial position with a magnetic field generated by the transducer.

Abstract: A method of generating a position error estimate generates a phase field signal and a position error field signal. A set of operations is performed on the phase field signal and the same set of operations is performed on the position error field signal. The result obtained by performing the set of operations on the position error field signal is divided by the results obtained by performing the set of operations on the phase field signal. The result of the division is the position error estimate. In addition, a demodulation circuit is provided that utilizes field ratioing.

Abstract: An asynchronous demodulator and method is provided which determines a position error of a read head relative to a position on a medium in a storage device. The read head generates a-read signal as the read head passes over a servo area on the medium. The demodulator generates a normal demodulating signal that is asynchronous with the read signal and a quadrature demodulating signal that is ninety degrees out of phase with the normal demodulating signal. The read signal is multiplied by the normal demodulating signal and the quadrature demodulating signal to produce a normal position signal and a quadrature position signal. The demodulator produces a position error magnitude and a position error direction based on the normal position signal and the quadrature position signal.

Abstract: A method of writing servo information for hard disc drives, and disc drives built according to the method are disclosed. The method includes writing position reference information on a reference disc surface prior to mounting a disc assembly into a hard disc drive. Once the disc assembly is mounted in the disc drive, servo information is written onto the disc surfaces based upon the pre-written position reference information. Subsequently, the position reference information can be erased or written over by user data.

Abstract: A method and apparatus for processing a magnetic disc prior to assembly of the disc in a disc drive storage assembly includes measuring a physical characteristic of the magnetic disc and encoding an information pattern within the magnetic disc. The information pattern is associated with the measured physical characteristic.