Abstract: Methods of controlling reading/writing by a read/write head of a disk drive include generating a position error signal indicative of a displacement of the read/write head from a desired radial location on a surface of a data storage disk. A control signal for moving the read/write head to the desired location is calculated responsive to the position error signal. Writing by the read/write head is inhibited responsive to the control signal exceeding a control signal threshold value. A disk drive includes a controller configured to generate a position error signal indicative of a displacement of a read/write head from a desired location on a surface of a disk, and to generate a control signal for moving the read/write head to the desired location. The controller is further configured to inhibit writing by the read/write head responsive to a predictive metric that is predictive of the position error signal exceeding a threshold.

Abstract: A cold seek governor process for a hard disk drive includes regulating delay between seek operations when temperature of the disk drive is below a threshold temperature.

Abstract: A magnetic head structure having enhanced protrusion and having a first pole structure, a second pole structure forming a yoke with the fist pole, a coil structure disposed in the yoke, and a layer of partially cured polymer operatively coupled to the yoke. Also disclosed is a magnetic head having a first pole structure, a second pole structure forming a yoke with the fist pole, a coil structure disposed in the yoke, and a layer of at least partially insulative material operatively coupled to the read and/or write head for providing enhanced protrusion, the at least partially insulative material having a coefficient of thermal expansion higher than a coefficient of thermal expansion of fully cured hard bake novalac. Further embodiments include disk drive systems having the head structures described herein.

Abstract: A disk drive uses a hybrid analog-digital acceleration feedforward control system and method for cancellation of rotational disturbances. A rotational vibration (RV) sensor is used with an analog circuit to generate an analog feedforward signal that is summed with the analog actuator control signal from the servo control processor. The analog feedforward signal is also converted to a digital feedforward signal and input to the processor. When the actuator gain deviates from its design value, the processor retrieves the appropriate actuator gain value from a lookup table. The processor uses the actuator gain value and the digital feedforward signal to calculate a modified feedforward signal, which is a fraction of the digital feedforward signal. The processor also calculates a feedback control value from the servo positioning information and a feedback controller.

Abstract: Embodiments of the invention provide a disk drive capable of writing information on data tracks even more positively when a shingle write method is adopted. In one embodiment, the disk drive is characterized in that, when information is to be written on a plurality of adjacent data tracks on a recording medium through the shingle write method, writing of information is controlled by detecting an actual writing position based on servo information recorded on the recording medium and determining whether or not the detected actual writing position meets a predetermined condition.

Abstract: A waveform generator generates an acceleration orbit, a velocity orbit, and a position orbit from the seek time. Each orbits multiplied by respective gains, whereupon the orbits are synthesized by a first adder. The resulting composite orbit is multiplied by a seek distance and then passed through a FIR filter to obtain the target position orbit that is to be applied to the later-stage two-degree-of-freedom control system. The two-degree-of-freedom control system has a characteristic whereby it is able to approximate a second-order low-pass filter.

Abstract: Embodiments of the present invention relate to retracting a magnetic head of a disk drive device to a retract position in accordance with a fall state, and to suppressing the performance degradation due to erroneous fall determinations as well as occurrence of damage by a head-disk crash. According to one embodiment of the present invention, in a Hard Disk Drive (HDD), a servo controller moves a head slider to a cylinder at the side of a ramp at a predetermined timing that a fall determiner determines that it is falling and an unload controller starts an unload process. This shortens the time between determination by the fall determiner that it is falling to retraction of the head slider to the retract position. Furthermore, it prevents increase of the erroneous determinations by relaxing the fall determination condition for safety. Also, it shortens the time that the head slider returns to the initial position before the seek in case that it is not determined that it is falling.

Abstract: Embodiments of the invention reduce a possibility that a head will collide with a medium when the clearance between the head and the medium is adjusted by using a medium, and sufficiently reduce the clearance even at an initial stage of accessing a data area. In one embodiment, a hard disk drive (HDD) keeps a heater in an OFF state for a period of time from the start of seek operation until the specified timing after a following mode starts. This prevents a head element from colliding with a magnetic disk, and also prevents flying properties from changing due to the deformation of the ABS. In the above specified timing, the heater is switched from OFF to ON. Specifically, for example, on completion of seek operation, in the timing in which a head arrives at a target track, or in the timing in which an HDC/MPU enters the following mode, the heater is turned ON.

Abstract: Upon obtaining a detection signal of a shock sensor that detects a shock applied to an apparatus for output, a write disabling unit disables writing by a head on a medium over a predetermined time corresponding to a shock convergence. A determining unit determines, during the write disable, whether an output of the shock sensor is a detection output of the shock sensor due to a shock or an erroneous detection output of the shock sensor due to power supply fluctuations. A sensitivity control unit increases a detection sensitivity of the shock sensor when the determining unit determines that the output is a detection output due to the shock, and decreases the detection sensitivity of the shock sensor and clears the write disable when the determining unit determines that the output is an erroneous detection output due to power supply fluctuations.

Abstract: A mechanical transport device includes a system for transport; and a hard disk drive attached to the system. The hard disk drive comprises a magnetic recording disk to record data, a head to read or write the data to or from the disk, and a drop sensor designed to sense a shock condition. The system for transport may be a vehicle such as a car.

Abstract: In a storage medium to which information is recorded by using a write head of an inductive type, in addition to a servo section in which servo information is recorded and a data section to which data is to be written, a write training section on which training write of pseudo-data is to be performed is disposed on a recording track. When the temperature is low, a write control unit writes the pseudo-data to the write training area and then writes data to the data area. By writing the pseudo-data to the write training area, a write core is heated and caused to project toward the medium surface side by thermal expansion, and the writing ability is enhanced; then, the data is written to the data section. A write training section is also disposed in front of a data section in a track of a system area of the storage medium, and, when the temperature is low, and when system information is to be written to the data section of the system area, pseudo-data is written to the write training section.

Abstract: A magnetic disk drive includes an actuator arm, a suspension fixed to a tip end of the actuator arm, and a head slider having at least two electromagnetic transducers mounted at a tip end of the suspension. The head slider has a first electromagnetic transducer inclined in a direction in which the inner side face side is nearer to an air outflow end than a central portion thereof, and a second electromagnetic transducer inclined in a direction in which the outer side face side is nearer to the air outflow side than the central portion thereof. A controller performs changeover control such that an inner side data region of a magnetic disk is taken charge of by the first electromagnetic transducer while an outer side data region is taken charge of by the second electromagnetic transducer.

Abstract: When an idle seek operation of a magnetic disk drive is executed under a velocity control utilizing a back electromotive force of a VCM actuator, the accuracy of the velocity control is deteriorated due to temperature variation of the VCM. To eliminate this disadvantage, a calibration of the velocity control is executed by using control information, such as a track number read from the magnetic disk medium. After the velocity control has been executed for an appointed period, by detecting the back electromotive force from the VCM actuator, an MR sense current and a power of a read write LSI are turned on for a time, positioning information on the magnetic disk medium is read out, parameters to be used for the velocity control are calibrated, and thus a stability of the control can be obtained.

Abstract: A disc drive controller circuit for an actuator receives reference data indicating a desired actuator position “?d”, error data indicating a difference “e” between the desired actuator position and a sensed actuator position “?”, and adaptive parameter data “”. The controller circuit calculates a circuit output “u” that drives the actuator. The controller circuit derives the circuit output “u” according to a formula: A ^ ? ( ? ¨ d + 2 ? ? ? ? ? e . + ? 2 ? e ) + k ? ( e . + 2 ? ? ? ? ? e + ? 2 ? ? 0 t ? e ? ? ? ? ) in which “?” is a controller zero value and “k” is a controller gain value and “t” is time. The adaptive parameter  is updated in general accordance with the formula: Â(k)=e1e2?t+Â(k?1).

Abstract: A hard disk drive that includes a voice coil motor controlled by a servo. The servo provides a driving signal that has multiple sinusoidal waveforms. The multi-sinusoidal waveforms minimize seek time and vibrations in the drive.

Abstract: Embodiments of the invention reduce a possibility that a head will collide with a medium when the clearance between the head and the medium is adjusted by using a medium, and sufficiently reduce the clearance even at an initial stage of accessing a data area. In one embodiment, a hard disk drive (HDD) switches a heater from OFF to ON in the specified timing after a seek mode is switched to a following mode. Specifically, for example, on the completion of seek operation, in the timing in which a head arrives at a target track, or in the timing in which an HDC/MPU enters the following mode, the heater is turned ON, and this state is kept unchanged until access to the target sector is made.

Abstract: A hard disk drive with a circuit that provides a control signal to a voice coil motor to move a head across a disk of a drive. The circuit includes a state estimator that provides a plurality of state estimates and a disturbance estimator that provides a disturbance estimate that is combined with the state estimates to define the control signal. The disturbance estimator compensates for flex cable disturbances, particularly during a settle mode of a seek routine.

Abstract: A hard disk drive with a voice coil motor circuit that provides a current to a voice coil motor to perform a seek routine in a seek time. The disk drive includes a temperature sensor to sense a temperature of the disk drive and a voltage sensor to sense the voltage of the voice coil motor. The circuit adjust the seek time dependent upon the sensed temperature and voltage. By way of example, the circuit will increase the seek time if there is an increase in temperature and/or a decrease in voltage.

Abstract: A feedforward compensator for induced vibration is disclosed. Controlled motions in an actuator induce mechanical disturbances in a surrounding cabinet. The feedforward compensator allows such disturbances to be compensated for without the need of a vibration sensor. The compensator provides a feedforward compensation signal configured to compensate for a mechanical disturbance predicted to be induced by a controlled motion of the actuator, and applies the feedforward compensation signal to a signal that controls the motion of the actuator.

Abstract: A hard disk drive with a servo circuit that provides a control signal to a voice coil motor to perform a servo to align a head with a disk track of the drive. The servo circuit includes a fifth order state estimator that provides five estimates that are used to create the control signal. The fifth order state estimator may incorporate a first flexible mode of the voice coil motor to calculate the estimates.

Abstract: A disk drive is disclosed comprising an actuator arm, a head attached to a distal end of the actuator arm, a voice coil motor for rotating the actuator arm about a pivot, and an optical sensor operable to generate a first position signal representing a position of the actuator arm with respect to the disk, wherein the first position signal is substantially unaffected by a vibration mode of the actuator arm. Servo sectors recorded on the disk are processed to generate a second position signal representing a position of the head with respect to the disk, wherein the second position signal comprises a significant component due to the vibration mode of the actuator arm. A control signal is applied to the voice coil motor in response to the first and second position signals.

Abstract: Embodiments of the invention provide a disk drive capable of preventing the deterioration of performance. In one embodiment, a disk drive includes a disk medium; a head capable of performing a read/write operation for accessing the disk medium to read information from and to write information to the disk medium; a head controller for controlling the position of the head so that the head describes a substantially spiral trajectory relative to the disk medium; and a controller capable of controlling the head controller, of performing a read/write operation for reading or writing information with reference to an identifier table associating sector identifiers identifying sectors on a specified track with logical block addresses, and of creating an identifier table for a track to be accessed next during the read/write operation.

Abstract: A disk drive control method and apparatus. In particular, a torque constant correction method and apparatus in a disk drive using a multiple sinusoidal seek servo scheme.

Abstract: A disk drive includes a rotatable storage disk, an actuator motor, a slider that magnetically interacts with the storage disk, and a drive circuitry. A portion of the slider moves between a first position wherein the slider does not contact the storage disk and a second position wherein the slider contacts the storage disk. The drive circuitry can detect when the position of the slider changes between these positions. In one embodiment, the drive circuitry monitors off-track movement of the slider to detect when the slider has moved between these positions. The drive circuitry can also current that is directed to the actuator motor that is used to compensate for off-track movement to detect when the slider moves between these positions. In yet another embodiment, the drive circuitry monitors a rotational velocity of the storage disk to detect approximately when the slider moves between these positions.

Abstract: A hard disk drive with a voice coil motor controlled by a circuit. The circuit provides a driving current to the voice coil motor to move a head of the drive in a seek routine. The seek routine includes a settle mode that has an initial state and a velocity versus head position eigenvector. The eigenvector is changed to coincide with on the initial state when the seek routine enters the settle mode. Changing the eigenvector to coincide with the initial state induces a head velocity and movement with minimal overshoot or undershoot during the settle mode.

Abstract: In method of feedback control for active damping of slider air bearing vibrations in a hard disk drive slider, a slider is isolated from ground. A velocity signal is acquired from the slider. The velocity signal is filtered to acquire a vibration signal. The vibration signal is adjusted in amplitude to achieve an amplitude adjusted vibration signal. The amplitude adjusted vibration signal is applied to the slider to actively dampen vibrations in the slider.

Abstract: In a seek control device based on a current observer control which performs two degree of freedom control, a current step difference to be generated when seek control is switched to following control is prevented. When seek control is switched to following control, a current step difference cancellation trajectory generation section calculates a current value Udiff for the amount of the step difference based on a difference between current values u(n) and u(n?1), and supplies a target position trajectory r?(n) (or target current trajectory) for offsetting this calculated value to a following controller. Therefore the current step difference of the output current is cancelled.

Abstract: A system is capable of detecting a “large” shock. In contrast to just any shock, a large shock exceeds some threshold of magnitude or duration and may generate particles and/or the deposit of particles on a recording head, which can result in write errors. Responsive to detection of a large shock, the system can take corrective action, such as executing one or more corrective action seeks after detection of the large shock or executing a series of corrective actions seeks during a certain number of load operations after detection of the large shock. RAW verifications may be performed to confirm correct write operation of the recording head after such corrective action.

Abstract: A disk drive selects seek speed and seek acoustics based on a history of seek requests from a host computer. The history of seek requests can include time intervals between seek requests, seek lengths of seek requests, locations of seek requests, a backlog of seek requests, whether seek requests are read requests or write requests, and whether seek requests are sequential or random.

Abstract: A hard disk drive with a voice coil motor controlled by a circuit. The circuit provides a driving current to the voice coil motor to move a head of the drive in a seek routine. The seek routine includes a settle mode that has an initial state and a velocity versus head position eigenvector. The eigenvector is changed to coincide with on the initial state when the seek routine enters the settle mode. Changing the eigenvector to coincide with the initial state induces a head velocity and movement with minimal overshoot or undershoot during the settle mode.

Abstract: A method, medium, and apparatus controlling a hard disk drive, and particularly, embodiments include methods, media, and apparatuses compensating for torque variations with respect to temperature variations in a seek servo operation, compensating for differences between modeling torque constants, used for servo designing, and actual torque constants. The method includes controlling gain of a seek control loop to vary depending on a torque constant temperature compensation value corresponding to a measured temperature of the hard disk drive, the seek control loop generating a seek driving current to be applied to a voice coil in the seek mode.

Abstract: A magnetic disk device includes a position and velocity demodulating circuit. In the position and velocity demodulating circuit, a difference calculating unit demodulates a moving velocity of a magnetic head based on a phase difference in servo signals as servo data in the same sector. An overflow detecting unit detects an overflow of the demodulated moving velocity and calculates a correction value for the overflow. The overflow is corrected based on the correction value. The corrected overflow is further corrected by a correction value of a repeatable velocity error for the demodulated velocity to output an accurate demodulated velocity.

Abstract: A method is disclosed for identifying wedge time shift zones on a magnetic disk of a disk drive. The disk drive further includes a spindle motor for rotating the disk at an operating speed in response to a spindle control current generated by a spindle control system, and a head that is actuated over the disk. During operation, the control systems causes a seek of the head across the disk and measures wedge-to-wedge times between servo wedges. The control system then calculates a wedge-to-wedge time shift value using the wedge-to-wedge times and determines whether the wedge-to-wedge time shift time value exceeds a predetermined threshold. If the wedge-to-wedge time shift value exceeds the predetermined threshold, then the control system identifies a wedge time shift zone, and stores information for compensating for the identified wedge time shift zone during disk operations.

Abstract: A magnetic recording and reproducing apparatus and a method of controlling the same, capable of increasing the output of a position control signal and performing a precise positioning control of a magnetic head. The magnetic recording and reproducing apparatus has: a magnetic recording medium on which a positional information is recorded in the form of burst signal groups each consisting of either one of a single concave portion and a single convex portion of a predetermined concavo-convex pattern formed of a magnetic layer; a gate circuit; and an integrator for calculating a area integral of a reproduced signal corresponding to each of the burst signal groups.

Abstract: The amount of position error written into a servo burst pattern can be reduced by using additional media revolutions to write the pattern. Where servo bursts are used to define a position on the media, trimming a first burst and writing a second burst on separate revolutions of the media will result in a different amount of position error being written into each burst. The end result will be a reduction in the overall error in position information. In order to further reduce the position error given by a combination of bursts, each burst also can be trimmed and/or written in multiple passes. The overall error in position should decrease as the number of passes used to write a burst combination increases. This description is not intended to be a complete description of, or limit the scope of, the invention. Other features, aspects, and objects of the invention can be obtained from a review of the specification, the figures, and the claims.

Abstract: A disk drive having a drive housing, a storage disk that is rotatably coupled to the drive housing, and a slider assembly that includes a head and a slider mover. The head reads data from the storage disk during a read operation and writes data to the storage disk during a write operation. The slider mover maintains the head at a read HtD spacing during the read operation, at a pre-write HtD spacing during the read operation prior to the write operation, at a write HtD spacing during the write operation, and at an idle HtD spacing when the drive is not performing the read operation or the write operation. The disk drive includes a drive circuitry that directs a read power level to the slider mover to maintain the head at the read HtD spacing, a pre-write power level to maintain the head at the pre-write HtD spacing, a write power level to maintain the head at the write HtD spacing, and a idle power level to maintains the head at the idle HtD spacing.

Abstract: A head position control device controls the position of a head with respect to a disk where post code is assigned to a servo frame. Servo frames of a disk is constituted by a servo frame not having a post code recorded in an inner side zone and a servo frame having a post code recorded in an outer side zone. The device reads the servo frame, demodulates a current position from the servo frame, drives an actuator according to the modulated position, and controls the position of the head to a target position. While implementing a high TPI, the inspection time for post codes can be decreased with a servo frame occupying ratio in consideration of the data format.

Abstract: A disk control apparatus controls a disk driving unit that performs read/write of data with a head. A vibration detecting unit detects a vibration of the disk driving unit. A disk control unit controls the disk driving unit based on the detected vibration.

Abstract: A seek control apparatus, a seek control method and a storage apparatus can prevent degradation of performance of a read/write head due to residual oscillations in a seek operation. The seek control apparatus for performing a seek control of a head comprises an MCU 11 that acquires control information corresponding to the externally indicated data length out of the control information stored in a storage section 18 storing the control information for seek control for each of a plurality of data length ranges and performs a seek control according to the acquired control information.

Abstract: A method used in a disk drive system for compensating a frequency component affecting servo control performance. The method includes detecting a frequency component affecting a servo control output in a disk drive/head during a manufacturing process and storing the detected frequency component in a nonvolatile memory device. A frequency component is read from a nonvolatile memory device corresponding to a selected head each time the disk drive is turned on by a user. A parameter value of a filter is determined by using a servo control circuit of the disk drive to suppress the read frequency component.

Abstract: A track following control apparatus and method for a hard disk drive (HDD) is disclosed and includes an estimator receiving a position error signal from a HDA and generating estimated state information for a magnetic head in response to the position error signal, and a controller receiving the estimated state information and generating a control signal controlling operation of the HAD, wherein the estimator and controller are variably configured according to a write mode or a read mode.

Abstract: An apparatus and method are provided for quickly and finely compensating for non-repeatable run out (NPRO) of a disc drive. The NPRO compensation control apparatus in a run out compensation apparatus of a system includes: a frequency estimator directly estimating a trigonometric function value of an NRRO frequency from a predetermined signal responding to the system using a correlation between a filter coefficient of a notch filter and a notch frequency; and an NRRO compensator canceling NRRO of the system using the trigonometric function value of the NRRO frequency estimated by the frequency estimator.

Abstract: A disk drive includes a drive housing, a storage disk, a slider and a drive circuitry. The storage disk has an inner and an outer diameter. The slider includes a read/write head and a slider mover that receives power from the drive circuitry to position the read/write head at a predetermined head-to-disk spacing during radial movement of the slider relative to the storage disk. The drive circuitry can direct a varying level of power to the slider mover during radial movement of the slider. In addition, the drive circuitry can increase the power to the slider mover as the read/write head nears a target track in order to decrease the head-to-disk spacing at the appropriate time. The drive circuitry can adjust the power to the slider mover so that the head-to-disk spacing remains within a predetermined range as the slider moves radially relative to the storage disk.

Abstract: A method is disclosed for writing repeatable runout (RRO) correction values to a disk of a disk drive. The disk has distributed position information in a plurality of embedded servo sectors. The transducer head has a read element that is offset from a write element. The write element is positioned over a target track while the distributed position information from a followed track is read using the read element. The target track is different from the followed track due to the offset between the read element and the write element. Previously determined RRO correction values associated with the target track are written at radial positions on the target track. The radial positions are based on the distributed position information of the followed track, previously determined RRO correction values associated with the followed track, and a portion of the previously determined RRO correction values associated with the target track.

Abstract: A disk drive actuator circuit adapted to retract a head assembly when a capacitor discharges energy to the voice coil. This voltage may be modulated to deliver peak torque to get the actuator over a ramp, yet also deliver a lower torque to suppress the initial head velocity when the actuator is over the disk.

Abstract: A method of determining, and an apparatus to determine, a track zero position of a disc in a disc drive, the method including seeking, sequentially, in units of predetermined numbers of tracks, outwardly from a designed track zero position to a predetermined critical track position of the disc; determining whether track following is performed normally during the seeking; and determining an actual track zero position by shifting the designed track zero position inward by a predetermined number of tracks in response to the track following not performing normally, and determining the actual track zero position to be the designed track position in response to the track following performing normally.

Abstract: Various methods and circuits are described for controlling movement of a read/write transducer. The acoustics that are generated when moving a read/write transducer are detected. Movement of the transducer is regulated in response to the detected acoustics.

Abstract: Servo writing a disk of a disk drive is disclosed. A phase locked loop (PLL) is synchronized to first sectors previously written on a first track, and second sectors are written to a second track using the PLL, wherein a plurality of phase errors corresponding to the second sectors are saved. A correction value is computed corresponding to a selected one of the second sectors, wherein the correction value is computed in response to a plurality of the phase errors generated for a plurality of the second sectors leading the selected sector. The PLL is synchronized to the second sectors using the correction value, a third sector is written to a third track using the PLL, and a phase error is saved corresponding to the third sector.

Abstract: The head gimbal assembly includes a slider and a micro-actuator assembly sharing power for the micro-actuator assembly to aid in positioning the slider and for an amplifier included in the slider to generate an amplified read signal when the slider read accesses data on a rotating disk surface included in a hard disk drive. The slider includes a read-write head providing a read differential signal pair to an amplifier to generate an amplified read signal reported when read accessing a rotating disk surface near the slider, which includes a read head employing a spin valve or employing a tunneling valve. Hard disk drive including a head stack assembly, which includes at least one of the head gimbal assemblies. Manufacturing the head gimbal assembly, the head stack assembly, and the hard disk drive, as well as these items as products of the invention's manufacturing processes.

Abstract: Embodiments of the present invention reduce noise and residual vibration during random access operation of a magnetic disk drive. The magnetic disk drive which executes each instruction from an upper device to move a magnetic head from a start track to an end track on a magnetic disk. In one embodiment, the magnetic disk comprises a processor configured, if a seek span from the start track to the end track, according to a seeking instruction from the upper device, is equal to a preset specific length, to store the seeking instruction for the specific length in memory, and to seek an alternative position from the start track for moving the magnetic head and then seek the end track specified in the stored seeking instruction from the alternative position for moving the magnetic head.