Abstract: A reference spiral is written on a recording surface of a magnetic storage disk that is free of position or timing information. The reference spirals are written on the recording surface with a substantially uniform slope by using open loop control of the position of a read/write head in conjunction with an iterative learning control scheme. A voltage profile applied to a voice coil motor is adapted over multiple iterations of moving the read/write head across the recording surface to closely approximate a target voltage profile, and the reference spiral is written using the adapted voltage profile. In addition, ramp contact detection based on actuator current profile may be employed to achieve full utilization of available actuator stroke.

Abstract: A reference spiral is written on a recording surface of a magnetic storage disk that is free of position or timing information. The reference spirals are written on the recording surface with a substantially uniform slope by using open loop control of the position of a read/write head in conjunction with an iterative learning control scheme. A voltage profile applied to a voice coil motor is adapted over multiple iterations of moving the read/write head across the recording surface to closely approximate a target voltage profile, and the reference spiral is written using the adapted voltage profile. In addition, ramp contact detection based on actuator current profile may be employed to achieve full utilization of available actuator stroke.

Abstract: A reference spiral is written on a recording surface of a hard disk drive. By launching writing of fine guide spirals from a launch point that is disposed on a pre-existing coarse guide spiral, writing of the fine guide spiral can be launched in response to a write head crossing the pre-existing coarse guide spiral, rather than in response to a precisely timed event. To enable launch points being disposed on pre-existing coarse guide spirals, launch points are not all located at the same radial position on the recording surface.

Abstract: In an in-drive erase process for erasing disk surfaces of a hard disk drive, erase spirals are written on multiple disk surfaces and at a different write frequency than that of other data patterns on the disk surfaces. The erase spirals written on a first disk surface can be used to control an erase process on a portion of the remaining disk surfaces. Erase spirals are then written on a different disk surface and can then be used to erase all data on the first disk surface. Consequently, even when every disk surface includes previously written data patterns that can potentially interfere with control of the erase process, the erase spirals so written can control the erase process with sufficient precision to thoroughly erase each disk surface.

Abstract: A method for determining a position error signal in a disk drive includes writing a servo signal that has a variable offset from a track center for a plurality of concentric tracks in a servo wedge on a disk surface, forming a spiral servo track, observing the offset values for the servo signal in the servo wedges at a first of the plurality of tracks, and observing the offset values for the servo signal in the servo wedges at a second of the plurality of tracks. The method also includes determining the first error amounts from the offset values at the first of the plurality of tracks, and determining the second error amounts from the offset values at the second of the plurality of tracks. If the first error amounts and the second error amounts are equal, using one of the first or second error amounts as a correction update to a head non-linearity look-up table.

Abstract: Methods in accordance with embodiments of the present invention can be applied to determine a width of a data stroke along a rotatable medium of a data storage device. In one embodiment, the width can be determined by measuring a distance from a marker zone edge of a template pattern to a ramp, and measuring a distance from the marker zone edge to an inner crash stop. A track layout can be determined based on the width of the data stroke.

Abstract: Systems and data storage devices in accordance with embodiments of the present invention can execute instructions to determine a width of a data stroke along a rotatable medium. In one embodiment, the width can be determined by measuring a distance from a marker zone edge of a template pattern on the rotatable medium to a ramp positioned adjacent to the rotatable medium or near the inner diameter of the rotatable medium, and measuring a distance from the marker zone edge to a crash stop. A track layout can be determined based on the width of the data stroke.

Abstract: Methods in accordance with the present invention can include determining a position of a head along a stroke by locating one or more marker-zones printed to a reference surface of a disk. The one or more marker-zones can be printed to a portion of the reference surface as one or more pulses from a template pattern that can further comprise a plurality of chevrons. In one embodiment, each pulse can trace the motion of the stroke along at least a portion of the radius of the reference surface. A pulse can identify a marker-zone edge when the pulse disappears at some radius from the center of the disk. By moving the head along the stroke, the marker-zone edge can be detected and a gross position determined. A fractional position can be determined by measuring a phase of a chevron located at substantially the same radial location as the edge.

Abstract: Template patterns in accordance with the present invention can include one or more marker-zones printed to a reference surface of a disk for determining gross-position along a stroke of a read head connected with a rotary actuator. The one or more marker-zones can be printed or otherwise written to a portion of the reference surfaces as one or more pulses. In one embodiment, each pulse can trace the motion of the stroke along at least a portion of the radius of the reference surface. A pulse can identify a marker-zone edge when a di-bit (a transition pair representing a pulse) disappears at some radius from center of the disk. At a radius closer to the center of the disk, the di-bit can abruptly reappear so that the pulse is continued. The interruption in the radial continuity of the magnetized pulse defines the marker-zone and can be any length.

Abstract: A disk drive having: (a) at least one data disk; (b) a brushless DC motor coupled to the data disk, the motor having: (i) multiple phase windings arranged as a stator, and (ii) a rotor having a permanent magnet or a DC current excitation winding for rotating the data disk; (c) a transducer for writing data to or reading data from the data disk; (d) a carrier supporting the transducer; (e) a voice coil motor coupled to the carrier for moving the carrier radially across the disk; (f) a drive controller coupled to the brushless DC motor and to the voice coil motor; and (g) a support for supporting the brushless DC motor, the voice coil motor and the drive controller. The drive controller periodically samples the rotor position and then drives the motor by energizing appropriate phase windings in relation to the rotor position that provide maximum forward torque to the rotor.