Abstract: A data storage device is disclosed comprising a head actuated over a disk. The head is used to read servo information from the disk and generate a position error signal (PES) representing a position of the head over the disk. A control signal is generated based on the PES and a triangle-shape dither signal, and the head is positioned over the disk using the control signal.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of spiral seed tracks. The head is positioned at a first radial location over the disk, and the head is servoed over the disk in response to the spiral seed tracks starting from the first radial location in order to write a first spiral servo track on the disk. The head is positioned at a second radial location over the disk different from the first radial location, and the head is servoed over the disk in response to the spiral seed tracks starting from the second radial location in order to write a second spiral servo track on the disk.

Abstract: A disk drive is disclosed comprising a plurality of disk surfaces including a first disk surface and a second disk surface. The disk drive further comprises a plurality of heads including a first head actuated over the first disk surface, and a second head actuated over the second disk surface, as well as a ramp proximate an outer diameter of the disk surfaces. A first interval is measured while moving the first head toward the ramp until the first head contacts the ramp, and a second interval is measured while moving the second head toward the ramp until the second head contacts the ramp.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of spiral tracks including a first spiral track. A DC spiral track error common to the spiral tracks is measured relative to an ideal slope for the spiral tracks, and an AC spiral track error is measured for each spiral track relative to the ideal slope. As the head approaches the first spiral track, a spiral crossing window is opened based on the measured DC spiral track error and the measured AC spiral track error for the first spiral track, and the first spiral track is detected after opening the spiral crossing window.

Abstract: A disk drive is disclosed comprising a disk comprising at least one spiral track, a head, and an actuator operable to actuate the head over the disk. A slope of the spiral track is measured at a plurality of radial locations across the disk, and a spiral track error at each radial location is generated based on a difference between the measured slope and a target slope. The head is actuated over the disk based on the spiral track and the spiral track error.

Abstract: A data storage device is disclosed comprising a disk surface comprising a first spiral track, and a head actuated over the disk surface. While reading the first spiral track on the disk surface, a second spiral track is simultaneously written on the disk surface. In one embodiment, the second spiral track is written in an opposite radial direction as the first spiral track, and in another embodiment the second spiral track is written in the same radial direction as the first spiral track.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, and a ramp near an outer diameter of the disk, wherein the ramp for unloading the head off the disk. The head is positioned at an inner diameter of the disk and then moved toward the ramp in response to a velocity profile. An interval is measured from a beginning of the movement until the head begins unloading onto the ramp, and the velocity profile is adjusted in response to the measured interval.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising servo information. A position error signal is generated while executing a first plurality of seek operations to seek the head over a seek length, and first feed-forward compensation values are adapted for a first segment of the seek length using an iterative learning control algorithm based on the position error signal. During a second plurality of seeks, second feed-forward compensation values are adapted for a second segment of the seek length using the iterative learning control algorithm based on the position error signal. The servo control system is operable to execute the second plurality of seek operations using the first feed-forward compensation generated for the first segment of the seek length.

Abstract: A disk drive is disclosed comprising a head actuated over a disk surface, the head comprising a temperature sensitive (TS) fly height sensor. The disk drive further comprises a ramp for parking the head, and control circuitry configured to process a fly height signal generated by the TS fly height sensor, wherein the fly height signal represents a fly height of the head over the disk, and detect whether the head is on the ramp in response to the fly height signal.

Abstract: A disk drive is disclosed comprising a disk, a head, and a voice coil motor (VCM) operable to actuate the head over the disk, wherein the VCM generates a back electromotive force (BEMF) voltage. At least one reference track is written on the disk, and the head is positioned near a first diameter of the disk. While moving the head from the first diameter toward a second diameter of the disk, the reference track is read and a first estimated state error is measured. While moving the head from the second diameter of the disk toward the first diameter of the disk, the reference track is read and a second estimated state error is measured. A gain and an offset of a velocity sensor are adjusted in response to the first and second estimated state errors.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, and a spindle motor operable to rotate the disk. A bootstrap spiral track is written to the disk, wherein the bootstrap spiral track comprises a high frequency signal interrupted by sync marks. A first sync mark is written while writing a first part of the bootstrap spiral track, and a second sync mark is written while writing a second part of the bootstrap spiral track. A switch between writing the first sync mark and the second sync mark is made in response to a spindle BEMF voltage, thereby generating a sync mark seam in the bootstrap spiral track.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, wherein a bootstrap spiral track is written on the disk. While servoing on the bootstrap spiral track at least one circular reference track is written on the disk. A velocity profile is adjusted in response to the circular reference track, and a plurality of spiral tracks are written to the disk in response to the velocity profile.

Abstract: In an embodiment of the present invention, a disk drive comprises a head actuated over a disk including a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. The read signal from the head is processed to detect a plurality of the sync marks in spiral track crossings. A plurality of timing recovery measurements are generated corresponding to the detected sync marks, and the timing recovery measurements are biased based on a radial location of the head. A servo write clock is generated in response to the biased timing recovery measurements, and the servo write clock is used to write product servo sectors to the disk.

Abstract: An embodiment of the present invention comprises a method of writing product servo sectors to a disk of a disk drive. The disk comprises a plurality of spiral tracks each having a high frequency signal interrupted at a predetermined interval by a sync mark. The head internal to the disk drive is used to read the spiral tracks to generate a read signal which is processed to detect the sync marks. An aberration is detected in the detected sync marks in order to locate an initial radial location of the head with respect to the disk. The read signal representing the high frequency signal in the spiral tracks is processed to generate a position error signal (PES) used to maintain the head along a substantially circular target path while using the head internal to the disk drive to write the product servo sectors along the circular target path.

Abstract: A method of writing product servo sectors to a disk of a disk drive is disclosed. The disk comprises a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted at a predetermined interval by a sync mark. The read signal from the head is processed to detect a plurality of the sync marks in a spiral track crossing. A timing recovery measurement is generated in response to a selected one of the sync marks based on reliability metrics, wherein a servo write clock is synchronized in response to the timing recovery measurement. The read signal representing the high frequency signal in the spiral track crossing is processed to generate a position error signal (PES) used to maintain the head along a substantially circular target path while using the servo write clock to write product servo sectors along the circular target path.

Abstract: A method of servo writing a disk of a disk drive is disclosed. The disk comprises a plurality of spiral tracks, wherein each spiral track comprises a high frequency signal interrupted periodically by a sync mark. A timing recovery measurement is generated in response to the sync marks, wherein the timing recovery measurement comprises a sinusoidal component. A timing compensation value is generated in response to the sync marks which estimates the sinusoidal component in the timing recovery measurement. A frequency control signal is generated in response to the timing recovery measurement and the timing compensation value, a servo write clock is generated in response to the frequency control signal, and the servo write clock and the head internal to the disk drive are used to write the product servo sectors to the disk.

Abstract: A method and apparatus is disclosed for writing product servo sectors to a disk of a disk drive to define a plurality of data tracks. The disk drive comprises the disk and a head actuated over the disk. The disk comprises a plurality of spiral tracks which are read using the head to synchronize a write clock and to generate a position error signal (PES) according to a PES algorithm used to maintain the head along a first servo track while writing product servo sectors along the first servo track. The PES algorithm is adjusted to seek the head to a second servo track, and the head is used to write product servo sectors along the second servo track.

Abstract: The present invention may be embodied in a method and a disk drive for improving head position accuracy during track following through real-time identification of external vibration. A selected track is followed using a servo control loop having a nominal gain and being responsive to position error signal samples generated based on a difference between head position samples and a reference head position value. A spectral power value within a predetermined frequency band is determined from a sequence of the position error signal samples. If a property of the spectral power value exceeds a threshold, the gain of the servo control loop is increased within the predetermined frequency band to attenuate the effect of external vibration on the position of the head over the selected track during track following.

Abstract: Disclosed is a disk drive having a plant with a moveable transducer and a servo controller that more precisely controls the transducer during short to medium seeks by producing a multi-rate feed-forward command effort signal.

Abstract: A method for switching signals using one of a plurality of mirrors in an array structure. The method includes determining an optical path to be formed between an input fiber and an output fiber. The method also includes determining a set of mirrors to be used to form the optical path. The set of mirrors includes at least a first mirror. The first mirror is coupled to a mechanical spring assembly and an actuation assembly. The method captures an analog signal indicative of a spatial position of the first mirror using a position sensing device. The sensing device is coupled to the mirror. The method also converts the signal analog signal into a digital signal. The method processes the digital signal indicative of the spatial position of the mirror using the digital signal processing device to obtain a characteristic of the mirror. The method provides a control signal based upon the characteristic of the mirror. The converts the control signal into an analog control signal.