Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo sectors defining a plurality of servo tracks, and a head actuated radially over the disk for generating a read signal. Each servo sector comprises a preamble comprising a first end and a second end, and each servo sector comprises a servo sync mark after the second end of the preamble. The servo tracks form a plurality of servo zones, wherein a servo data rate of the servo sectors in a first servo zone is different than a servo data rate of the servo sectors in a second servo zone. The first end of the preambles in the servo sectors are aligned along a radius of the disk across at least the first servo zone and the second servo zone.

Abstract: A disk drive is disclosed comprising a disk having a plurality of servo sectors defining a plurality of servo tracks that form a plurality of servo zones. The disk drive further comprises a head actuated radially over the disk for generating a read signal, and control circuitry including a timing circuit. The timing circuit is initialized with a nominal center frequency that approximates an average servo data rate out of the plurality of servo zones. The timing circuit is synchronized to the read signal to generate synchronous read signal samples. A servo sync mark is detected from the synchronous read signal samples, and the servo zone the head is reading is estimated after detecting the servo sync mark.

Abstract: A disk drive is disclosed including a disk having a plurality of data tracks, wherein each data track comprises a plurality of data sectors and a plurality of servo sectors, and each servo sector comprises a plurality of servo bursts. A data path comprising a data decoder decodes a data read signal generated as a head passes over the data sectors, and a servo path demodulates a servo read signal generated as the head passes over the servo bursts. The servo path comprises a low pass filter operable to extract a low frequency component from the servo read signal, wherein the low pass filter does not operate on the data read signal. The servo path further comprises a subtractor operable to subtract the low frequency component from the servo read signal to generate a servo burst signal, and a servo demodulator operable to demodulate the servo burst signal.

Abstract: A disk drive includes a disk comprising a plurality of zones, a clock for generating a timing signal having a timing frequency, a voltage controller for providing a supply voltage, and circuitry coupled to the supply voltage and responsive to the timing frequency. Power may be conserved by receiving a host command; selecting one of the plurality of zones based on the host command; and adjusting the timing frequency and the supply voltage provided to the circuitry based at least in part on the selected zone.

Abstract: Disclosed is a disk drive having a disk, a masked read-only memory (ROM) device, a reprogrammable nonvolatile memory device, and a microprocessor for executing program code. The disk has a magnetic data storage surface with embedded servo wedges for defining data storage tracks including reserve tracks. The masked ROM device stores program code for implementing a spindle motor controller, program code for implementing a portion of a servo controller for track following along a data storage track, and program code for implementing a portion of a disk controller for controlling writing disk data to and reading disk data from the reserve tracks. The reprogrammable nonvolatile memory device stores data parameters relating to the disk drive's configuration. The reserve tracks store program code for implementing a cache control system for controlling caching of disk data in a cache memory.

Abstract: Disclosed is a rotating media storage device (RMSD) that has at least one calibration track with unique calibration servo synch marks (SSMcs). The RMSD includes a disk that comprises a plurality of tracks including a calibration track having a plurality of normal servo wedges distributed around the calibration track. At least one of the normal servo wedges includes a normal servo synch mark (SSMN). Further, at least one calibration servo wedge is distributed between a pair of normal servo wedges. The calibration servo wedge includes a calibration servo synch mark (SSMC). The calibration SSMC includes a pattern that is different than the pattern associated with the normal SSMN.

Abstract: Disclosed is a magnetic disk having servo sectors for defining data tracks. Each servo sector includes a preamble field and a null servo burst field. The preamble field is for synchronizing a phase-locked loop oscillator and defines a reference phase angle. The null servo burst field includes first and second servo bursts that are radially adjacent and have opposed phase angles such that a read along a null path that is equally between the first and second servo bursts generates a read signal of substantially zero amplitude, and a read along a path that is offset from the null path generates a read signal having an amplitude indicating a distance between the offset path and the null path, and having a phase indicating an offset direction. Further, the phase angle of the first and second servo bursts are substantially different from the reference phase angle.

Abstract: A disk drive includes an actuator assembly having a read/write head, a spindle motor, a disk mounted for rotation on the spindle motor, a wedge-to-wedge timer and a sector size selector. The disk includes a recording surface having a plurality of tracks and each track includes a plurality of servo wedges. The recording surface has at least one data sector between circumferentially adjacent servo wedges on each track. The wedge to wedge timer measures the time elapsed between at least two successive detections of circumferentially adjacent servo wedges and outputs a wedge-to-wedge correction signal that is dependent upon the measured elapsed time. The sector size selector outputs a sector size signal that changes according to the wedge-to-wedge correction signal. In turn, the sector size signal determines the size of the next data sector on the recording surface of the disk.

Abstract: A method for reducing the length of servo-wedges in a disk drive comprising a concentric tracks, each track comprising embedded servo-wedges each having a track identification field (TIF) and a servo-wedge identification field (WIF), wherein the embedded servo-wedges are grouped into servo-wedge groups comprising a first and second sub-group of servo-wedges. The method includes selecting a servo-wedge from a selected servo-wedge group; storing a first subset of a track identification data (TID) corresponding to a selected track in TIF of selected servo-wedge; storing a second subset of TID in a first portion of WIF of selected servo-wedge if selected servo-wedge is in second sub-group; storing a first wedge identification data (WID) corresponding to selected servo-wedge in a second portion of the WIF if selected servo-wedge is in second sub-group; and storing a second WID corresponding to selected servo-wedge in WIF if selected servo-wedge is in first sub-group.

Abstract: A disk includes an actuator assembly, a spindle motor and a disk that defines a plurality of servo wedges. A wedge to wedge timer is configured to measure the time elapsed between at least two circumferentially adjacent servo wedges and to output a wedge to wedge correction signal that defines a count between circumferentially adjacent servo wedges that is dependent upon the measured elapsed time. A servo frequency generator is configured to output a servo frequency generator signal having a frequency that is modulated by the wedge to wedge correction signal. A spindle motor control timer outputs a spindle control timer signal that is dependent upon the servo frequency generator signal and upon the time elapsed between at least two successive detections of circumferentially adjacent servo wedges. A spindle motor controller controls the spindle motor with a control signal that changes according to the spindle control timer signal.

Abstract: A disk drive includes a moveable head and a disk having a circumferential track which includes a plurality of servo wedges. The servo wedges are spaced sequentially around a circumference of the circumferential track. Each servo wedge includes an extended servo header. The disk drive includes a servo controller to perform track following with the moveable head. The servo controller compensates for servo wedge timing errors due to eccentricity associated with the servo wedges of the circumferential track by implementing: a first mode in which the servo controller locks to the extended servo header of a servo wedge and performs servo wedge timing error learning to characterize servo wedge timing errors and a second mode to adapt servo control signals of the servo controller based on the characterized servo wedge timing errors of the first mode in order to dynamically compensate for the eccentricity associated with the servo wedges.

Abstract: A disk drive has a spindle motor, a disk mounted for rotation on the spindle motor, and a head for reading from and writing to the disk. The disk includes a recording surface having a track that includes a first full servo wedge and a second full servo wedge, each of the first full and second full servo wedges defining a leading end and a trailing end and having, between leading and trailing ends, a preamble, a servo sync word, a track ID, and a plurality of servo positioning burst fields. The recording surface further includes user addressable data locations and a first partial servo wedge disposed between the trailing end of the first full servo wedge and the leading end of the second full servo wedge. The first partial servo wedge is devoid of preamble, track ID and wedge ID and includes a short servo sync mark that is different from the servo sync word. The servo sync mark defines a predetermined bit pattern that is immediately followed by a plurality of servo bursts.

Abstract: A disk drive has a sampled servo system controller and a disk. The disk has a plurality a plurality servo burst fields, each including a first normal burst field, a first quadrature burst field, a second normal burst fields and a second quadrature burst field. A portion of the first quadrature burst field is circumferentially contiguous with the first normal burst field and spans a portion of a radial extent of the first normal burst field. The second normal burst field is radially aligned with and away from the first normal burst field and spans a portion of a radial extent of the first quadrature burst field. The second quadrature burst field is radially aligned with and away from the first quadrature burst field and spans a portion of a radial extent of the second normal burst field.

Abstract: A disk drive has a sampled servo system controller and a disk. The disk has a plurality a plurality servo burst fields, the plurality of servo burst field including first and second normal burst fields, and first and second quadrature burst fields. A portion of the first quadrature burst field is circumferentially contiguous with the first normal burst field and spans a portion of a radial extent of the first normal burst field. The second normal burst field is radially aligned with and away from the first normal burst field and spans a portion of a radial extent of the first quadrature burst field. The second quadrature burst field is radially aligned with and away from the first quadrature burst field and spans a portion of a radial extent of the second normal burst field. The first normal burst field and the first quadrature burst field have a same first phase and the second normal burst field and the first quadrature burst field have a same second phase. The first phase is different than the second phase.

Abstract: Disclosed is a rotatable media storage device (RMSD) connectable to a host. The RMSD include a movable head to perform track following, a disk, and a synch mark detection circuit. The disk includes a circumferential track that has a plurality of embedded servo wedges utilized in track following. The synch mark detection circuit has a first detection mode and a second detection mode. In the first detection mode, the synch mark detection circuit detects a servo synchronization signal based on the head reading a SSM of a servo header of an embedded servo wedge. In the second detection mode, the synch mark detection circuit detects a servo synchronization signal based on the head reading a SSM and a wedge identifier of a servo header of an embedded servo wedge. The wedge ID is utilized in conjunction with the SSM to validate the servo synchronization signal.

Abstract: A disk drive has a sampled servo system controller and a disk. The disk has a plurality a plurality servo burst fields, the plurality of servo burst field including first and second normal burst fields, and first and second quadrature burst fields. A portion of the first quadrature burst field is circumferentially contiguous with the first normal burst field and spans a portion of a radial extent of the first normal burst field. The second normal burst field is radially aligned with and away from the first normal burst field and spans a portion of a radial extent of the first quadrature burst field. The second quadrature burst field is radially aligned with and away from the first quadrature burst field and spans a portion of a radial extent of the second normal burst field. The first normal burst field and the first quadrature burst field have a same first phase and the second normal burst field and the first quadrature burst field have a same second phase. The first phase is different than the second phase.

Abstract: Disclosed is a rotatable media storage device (RMSD) that performs servo synchronization based on a servo synch mark (SSM) that conflicts with self-clocking encoding algorithms. The RMSD includes a disk having a plurality of tracks wherein each track comprises a plurality of data regions interspersed between servo wedges. The servo wedges comprise a servo synch mark field including a servo synch mark (SSM) and a track identification field including a track identifier (TKID). The TKID is encoded in accordance with a self-clocking encoding algorithm whereas the SSM is encoded in accordance with a second algorithm that conflicts with the self-clocking encoding algorithm of the TKID. Thus, the SSM is prevented from being decoded as a portion of the TKID.

Abstract: A disk drive is disclosed comprising a plurality of disk surfaces and a plurality of respective heads actuated radially over the disk surfaces. Each disk surface comprises a plurality of tracks, each track comprising a plurality of data sectors and a plurality of embedded servo sectors, each embedded servo sector comprising a servo sync mark for synchronizing to the embedded servo sector. When the disk drive switches heads, a detection window for detecting the servo sync mark is opened early. An asynchronous gain control algorithm prevents a gain control system from diverging while reading an area of the disk surface preceding the servo sync mark, and a synchronous gain control algorithm maintains a proper gain of the read signal while reading the servo sync mark.

Abstract: A method of writing servo tracks on the disk surfaces of a hard disk drive. The method involves simultaneously writing partial servo tracks, called servo wedges, until a complete first set of servo wedges is written on all the disk surfaces. Then the disks are rotated until the heads of the disk drive are correctly positioned to simultaneously write subsequent servo wedge sets. This process is repeated until enough servo wedge sets are written to complete a first servo track on all the disk surfaces. Then, the heads are pivoted to a new radial position to begin writing a new servo track just as before. Simultaneously writing servo wedges advantageously expedites the often costly servo writing process.

Abstract: A disk drive is disclosed comprising a disk having a plurality of tracks, each track comprising a plurality of data sectors for storing user data and a plurality of embedded servo sectors for storing servo data. The disk drive further comprises a head comprising a read element and a write element, wherein the read element is offset from the write element. The disk drive stores a plurality of read repeatable runout (RRO) estimated values and a plurality of write RRO estimated values which are introduced into a servo loop to compensate for the different RRO disturbances which manifest during read and write operations.