Abstract: To account for head misplacement while servowriting, adjustments to thresholds used during writing and/or trimming of servo information can be used. A threshold can be used to disable servowriting when it is determined that servo information will not be written and/or trimmed at a desired location or within a threshold distance of a desired location. In multiple pass servowriting, a threshold can be adjusted for a pass or step or portion thereof using a position-error during a corresponding operation. For example, the position-error while trimming a first servo burst can be determined. Using the position-error, the threshold can be adjusted. The adjusted threshold can be used while writing a corresponding second servo burst. The threshold can be increased in a direction opposite to the determined position-error and decreased in the direction of the determined position-error. In this manner, the probability that the two bursts will identify a desired location can be increased.

Abstract: The present invention may be regarded as a disk drive comprising a disk having a plurality tracks, each track comprising a plurality of data sectors. If an error occurs while attempting to read one of the data sectors, a retry operation is executed in an attempt to recover the errant data sector. Averaged read data is generated over multiple retry operations, and the averaged read data processed to recover the errant data sector. In one embodiment, the averaged read data comprises an averaged binary sequence detected over multiple retry operations. In another embodiment, the averaged read data comprises averaged read signal sample values generated over multiple retry operations.

Abstract: Tilt between a head stack and its associated disk stack in a hard disk drive (HDD) is measured by determining the deviation of a target head from its expected position (based on the position of the current head) each time electrical contact is switched from the current head to a target head. A running average tilt value is stored and used to modify the logical seek distance used in a Rotational Position Optimization (RPO) algorithm to better order I/O requests in a queue. Also, the running average tilt value can be used by the servo to pre-position the target head before electrical contact is made with the target head, to improve speed of operation.

Abstract: A method is presented for precompensation of Non-Linear Transition Shift (NLTS) in magnetic recording media using a perpendicular recording write head. The method includes maintaining a count of non-transition data bits (“zeroes”) preceding a data transition (“one”) to be written. A precompensation value is assigned which correlates to the count of non-transition data bits preceding the data transition to be written. The assigned precompensation value is then applied to delay timing of a write signal sent to the perpendicular recording write head so that the location of the actual written data transition more closely aligns with an ideal location of the data transition to be written.

Abstract: A method and apparatus for overwriting data in a disk drive is provided. In one embodiment, a disk drive includes a disk surface and a write head associated therewith. The disk surface has servo information and user data written thereon. The user data is written by the write head. User data is overwritten by sweeping the write head from a first radius on the disk surface to a second radius on the disk surface, while the write head is actively writing.

Abstract: A method for measuring the clearance of a slider over a rotating disk by inducing a collision between the slider and the disk is described. After the normal flying height of the slider is established, the slider is driven into a collision with the rotating disk surface by applying a DC or AC voltage between the slider and the disk. The clearance data can be extracted from the induced collision by measuring a parameter, such as the change in the amplitude of the readback signal from the magnetic sensor, which is related to fly-height at the normal fly-height and at the disk surface. The two data points can then be used to derive the clearance. One embodiment uses a single beam interferometer to derive the vibrational displacement of the collision event.

Abstract: User data is read from a medium having servo data and user data encoded thereon. The user data is read with a read/write head that is operable in a write mode and a read mode. Servo data is read in a time window following a transition from write mode to read mode, with a frequency passband that has a first low frequency corner. User data is read from the medium after expiration of the time window, with a frequency passband that has a second low frequency corner that is lower than the first low frequency corner.

Abstract: A disk drive includes a transducer and a rotatable disk, which includes a plurality of tracks. A vibration state of the transducer relative to the disk is determined. The transducer is positioned relative one of the tracks based on a compensation scheme that varies based on the determination of the vibration state. The compensation scheme may be varied by selecting among output of two or more compensators, based on the determined of the vibration state of the transducer, to control positioning of the transducer. The compensation scheme may alternatively, or additionally, be varied by varying a contribution from a vibration state actuator compensator to the control of positioning of the transducer. The vibration state actuator compensator is configured to improve transducer track following while the transducer is subjected to vibration.

Abstract: According to one aspect, methods and systems for determining the position of a recording head using existing data structures on magnetic storage media are provided. In one example, a recording head writes data to an active track on a magnetic storage tape, the recording head including a write element and a read element in a known spatial relationship, wherein the read element is configured to access at least a portion of a reference track when the write element is accessing the active track. A controller determines a relative position of the transducer element to the reference track and repositions the recording head to write data to the active track. The read element may be a backward channel reader or dedicated read element of the recording head for reading reference tracks during read and/or write operations.

Abstract: A disk drive is disclosed having a disk comprising a plurality of spiral tracks, a head actuated over the disk, and control circuitry operable to process the spiral tracks in an interleaved manner to write a plurality of product servo sectors to the disk to define a plurality of radially spaced, concentric data tracks.

Abstract: A magnetic storage medium formed on a front major surface of a tape substrate defines a multiplicity of longitudinal data recording and playback tracks, each track having a nominal lateral location relative to the other tracks: and a predetermined optically manifested track servo pattern defined on the back major surface of the tape for indicating lateral displacement of the tape from a nominal lateral location of the track during tape movement across a read/write head. A magnetic tape recording and playback system employing the magnetic storage medium is also disclosed.

Abstract: A method of controlling starting current of an adaptive spindle motor in consideration of maximum allowable consumption power and a disk drive using the method. The method includes measuring a supply voltage supplied to the disk drive, calculating a maximum current that can be supplied to the spindle motor in a range of maximum allowable power in correspondence to the supply voltage measured in the measuring of the supply voltage, and applying the calculated maximum current to the spindle motor to start the spindle motor.

Abstract: A method, computer program product and hard disk drive for restricting a rate of spin-up/spin-down cycles for a spindle motor in a hard disk drive. The firmware in the hard disk drive determines a maximum rate of spin-up/spin-down cycles the spindle motor is designed to handle over a designated period of time based on the number of spin-up/spin-down cycles the spindle motor is designed to handle over its expected lifetime. The firmware disables the automatic standby mode of operation if a calculated rate of spin-up/spin-down cycles during the designated period of time is greater than the maximum rate of spin-up/spin-down cycles the spindle motor is designed to handle over the designated period of time. By disabling the automatic standby mode of operation, the rate of spin-up/spin-down cycles will be reduced as the spindle motor will not incur a spin-up/spin-down cycle until the automatic standby mode of operation is enabled.

Abstract: To account for head misplacement while servowriting, conditional writing and/or trimming of servo information can be used. Conditional servowriting allows servowriting to be disabled when it is determined that servo information will not be written and/or trimmed at a desired location or within a threshold distance of a desired location. For example, if a distance between a write element or a predicted location of servo information and a desired location of the servo information or write element exceeds a threshold, writing and/or trimming can be inhibited. Servowriting can be resumed when it is determined that servo information will be written or trimmed at a desired location or within a threshold distance of a desired location. A servowriting step or pass is not re-started when the threshold is exceeded and those wedges for which servo information was not written and/or trimmed can be attempted during subsequent revolutions of the rotatable storage medium.

Abstract: An additive self-servowriting method that records a servo pattern on a disk surface in a disk drive is disclosed. A servowriting method according to the present invention writes an initial servo pattern with a head moved to the inner circumference of the disk at the initial time. Then, additive servowriting operation is performed to write an additive servo pattern with the head positioned in the outer circumferential direction of the disk. When it is impossible to continue the additive servowriting operation in the middle of the operation, the head is set back to the previous additive servo pattern to resume the additive servowriting operation.

Abstract: A system controls the speed of a Voice Coil Motor (VCM) in order to perform the ramp loading of hard disk heads with low noise. This system includes a generator for generating a discontinuous PWM drive signal to a power stage. A sampling block is clocked by a synchronization signal issued from the generator and receives as an input a signal related to the electromotive force (Bemf) provided by the VCM motor. An adder node placed at the sampling block output receives a signal related to a reference electromotive force (Bemf_ref). A filtering block placed downstream of the adder node generates a power supply voltage signal to the power stage. The control system further includes a control block having at least one voltage divider and controlled switches. The control block is input the signal issued from the filtering block and control signals from the generator block to selectively operate the controlled switches and set the value of the power-on signal of the power stage.

Abstract: A method for secondary-actuator failure-detection and recovery in a dual-stage actuator disk drive includes running a calibration test by the servo control processor and measuring the position of the secondary actuator relative to its neutral position in response to the calibration test. The secondary-actuator failure detection and calibration test can be performed on a regular schedule or at selected times, such as at disk drive start-up. With the primary actuator biased at a test location, such as a crash stop or a load/unload ramp, the servo control processor generates a test signal to the secondary actuator and receives a relative-position signal (RPS) from the relative-position sensor in response to the test signal. The test comprises two measurements: a measurement of the secondary actuator static characteristics, and a measurement of the secondary actuator dynamic characteristics.

Abstract: A data storage apparatus comprises a tape cartridge having a cartridge memory which is configured to store data representing a distinctive identity of the memory and data representing a distinctive identity of the cartridge. The cartridge has a data storage tape storing WORM data in a succession of data sets. Each data set is recorded with data representing a respectively associated data set information table. The data set information table includes an identifying data structure including data representing the identity of the cartridge memory and the data representing the identity of the cartridge. The integrity of all the WORM data written at any point along the tape can be checked against tampering by reference to the data structure that is recorded with each WORM data set.

Abstract: A controller providing increased control with lesser final error for an actuator when there is a force accelerating the actuator, such as at the end of travel during a retract operation. An extension of the integrator may be provided for implementing a second direction to integrate a final error. One embodiment of the invention may comprise a counter and an analog multiplexer controlling the attenuation of the command voltage.

Abstract: An apparatus and method for controlling head loading in a disk drive including a displacement measuring unit measuring a vertical displacement of a disk, a rotational angle detecting unit detecting a rotational angle of a spindle motor, and a controller controlling the movement of an actuator to load a head on the disk while a vertical displacement of a portion of the disk on which the head is loaded is decreasing so that the disk separates farther from a position on which the head is parked. Therefore, the possibility of collision between the head and the disk during head loading is reduced, thereby preventing damage to the head and disk and improving the reliability of the disk drive.