Abstract: An apparatus, method, and system for providing a fine adjustment for transducing head positioning in a hard disk drive (HDD). The apparatus, method, and system include reading a positioning error field wherein the resulting signal is a substantially sinusoidal position error signal (PES), filtering the PES to remove low frequencies and attenuate high frequencies, sample the filtered PES at a multiple of the channel frequency, filter the higher frequency harmonics, down sample the PES, and provide a signal proportional to the amplitude of the down sampled PES. This signal is the reference signal to the head positioning servo.

Abstract: A head positioning control system which is applied to a disk drive is disclosed. The system includes a feedback control system which performs head positioning control of a head and a feedforward control system. The feedforward control system detects the amplitude and phase of a disturbance based on the position error between the position of the head and a target position. The feedforward control system computes a disturbance compensation value for eliminating the disturbance to output the disturbance compensation value to the feedback control system based on each detection result of the amplitude and the phase.

Abstract: A disk drive is disclosed comprising a disk having a plurality of tracks, a head actuated over the disk, and control circuitry for servicing an access command received from a host, wherein the access command identifies at least one of the tracks. The control circuitry identifies a band of tracks associated with the access command, maintains a counter for tracking an amount of time the head is within the band of tracks, and moves the head out of the band of tracks in response to the counter to facilitate wear prevention.

Abstract: A disk device performs position control of a head. An acquiring unit acquires correction information and check information from a disk for checking the correction information. A judging unit judges whether the correction information acquired should be used for correcting position information recorded in the disk, based on the correction information acquired and the check information acquired.

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: A method and program product supporting adjusting a temperature of a hard disk drive (HDD) during testing. An HDD test program is performed within a pre-determined optimal test temperature range. The HDD is kept within this pre-determined test temperature range by switching HDD operation modes back and forth between a higher heat generating Rapid Seek Mode and a lower heat generating IDLE mode. The HDD is thus kept within the optimal test temperature range without the use of external heating and/or cooling devices.

Abstract: A head positioning method and device positions a head which reads a disk-type storage medium at a specified location, and accurately estimates a bias value during settling control. A disk device includes a disk medium, a head, an actuator, and a control circuit, and settling control is performed based on a detected position after coarse control without integral compensation or bias compensation having been performed. The position of the head for a next sample is estimated, and an initial bias value is estimated from the difference between the detected position and the estimated position. This initial bias value is then used to perform settling control together with integral compensation of bias compensation. Since the accurate initial bias value at the start of settling is estimated, it is possible to reduce the time for correcting the shift in the bias during settling control, and greatly reduce the time required for settling control.

Abstract: Embodiments of the invention provide a magnetic disk drive and magnetic disk drive control method for unloading a head safely with a simple configuration when a positioning control signal cannot be detected due, for instance, to a seek error. In one embodiment, when a head cannot detect servo information prerecorded on a disk, a positioning control section resets and starts a time counting section, and switches to an unloading control section for causing the unloading control section to output a position control signal to a VCM driver. The time counting section counts tacho-pulses generated by a motor driver, and outputs time information. The unloading control section receives the time information from the time counting section. In accordance with the received time information, the unloading control section computes the position control signal that the positioning control section outputs to the VCM driver.

Abstract: A magnetic disk apparatus comprising a magnetic disk 1, a head, a servo-information detecting unit 3, a servo-information position calculating unit 4, a write-permission determining unit 15, a data-writing unit 6, and a head-drive control unit 17. Servo information and data are recorded on the disk 1. The head reads and writes data from and on the magnetic disk 1. The servo-information detecting unit 3 detects a present head position from a signal supplied from the head. The write-permission determining unit 15 calculates a present head speed and a present head acceleration from the present head position and a previous head position detected in the past, and determines whether data can be written, from the present head position, the present head speed and the present head acceleration. The data-writing unit 6 writes data in accordance with a decision made by the write-permission determining unit 15. The head-drive control unit 17 drives the head in accordance with the present head position.

Abstract: In conventional magnetic disk drives where stream data are treated, seek operations are performed at unnecessarily high speeds. This put the magnetic disk drives at a disadvantage in suppressing noise, reducing power consumption, and lowering the costs of actuator components. In one embodiment of the invention, a magnetic disk drive comprises a magnetic disk medium; a magnetic head; a head actuator to move the magnetic head relative to the magnetic disk medium; and a controller configured to control the head actuator to move the magnetic head to record data to and reproduce data from the magnetic disk medium. The controller is configured to control the magnetic head to record stream data on the magnetic disk medium in such a manner that the stream data is recognizable as stream data. The controller is configured to detect a situation in which two or more stream data are to be recorded or reproduced concurrently so as to set a slower seek operation mode.

Abstract: A disk drive is disclosed comprising a disk and a voice coil motor (VCM) having a voice coil for actuating a head over the disk. A VCM driver comprises an H-bridge driver having a plurality of driver switches for driving current through the voice coil to ground. A first pulse width modulated (PWM) signal controls a first voltage level driving the voice coil relative to a duty cycle of the first PWM signal, and a second PWM signal controls a second voltage level driving the voice coil relative to a duty cycle of the second PWM signal, wherein the first voltage level is greater than the second voltage level.

Abstract: An apparatus and method for tracking radially-dependent repeatable run-out in a disc drive having a servo loop for positioning a head over a rotating disc is provided. The disc includes multiple tracks. Radially-dependent repeatable run-out control components for at least a subset of the multiple tracks are first determined. Data representative of the radially-dependent repeatable run-out control components for the subset of the multiple tracks is then stored. The stored data representative of the radially-dependent repeatable run-out control components is retrieved before settling on the target track, and subsequently used to follow the selected track.

Abstract: In a disk device having a ramp-load mechanism, stable retry operation is performed even upon occurrence of seek errors. A disk device is provided with a ramp to which the head is retracted from the disk, at the time of seek error retry, prior to beginning seek retry, checks whether the head has climbed onto the ramp. And if the head has not climbed onto the ramp, normal seek retry is performed, but if the head has climbed onto the ramp, unloading is first performed before seek retry. Consequently crashes due to climbing onto the ramp due to a seek error in a ramp-load device can be prevented, and improvement of device reliability can be expected.

Abstract: The blending of control indicators of a non-linear seek mode control and settle mode is done in a transition period between a non-linear seek mode and settle mode of the arm actuator in a hard disk drive. Such a blended transition avoids acoustical clicking that can occur for short distance seeks.

Abstract: An access performance adjusting method is adapted to a storage apparatus having a storage to prestore a skew quantity that is used to shift a data write starting position of each track of a recording medium depending on a head moving time required to move a head from one track to another track during a sequential access in which a plurality of tracks of the recording medium are accessed sequentially. The method includes measuring an apparatus performance with respect to a combination of the head and the recording medium, calculating a skew adjusting quantity with respect to the combination based on a reference apparatus performance and the measured apparatus performance, and adjusting the skew quantity read from the storage by the skew adjusting quantity and storing the adjusted skew quantity in the storage as an updated value of the skew quantity.

Abstract: A generic manufacturer-independent method to produce a metric of hard disk drive performance includes executing accesses from a reference sector on disk to several equidistantally-spaced target sectors, and recording the times of the accesses. These times are then ordered and used to generate shortest access times along with probabilities of achieving those access times, losing a disk revolution while accessing the target sector, and losing a disk revolution while executing a read/write operation.

Abstract: An off-track retry method for recovering data incorrectly read due to a read error caused by an off-track error in a disk drive. The off-track retry method includes extracting read gain characteristics while varying an off-track amount, determining an off-track amount, i.e., off-track direction and degree, based upon the read gain characteristics, reading data using the determined off-track amount, and determining whether the read data is normal and determining whether the data incorrectly read due to the read error has been recovered based upon the result.

Abstract: Provided are a method of generating a current trajectory for seek control of a hard disc drive and a seek control system using the same, the method including setting a current trajectory from harmonics of a sinusoidal wave; calculating a power consumed by a target device to be controlled using the current trajectory; and determining coefficients of the harmonics so as to minimize the power consumed by the device.

Abstract: Methods and computer program products for determining accurate estimates of coil resistance are provided. Current differences between pairs of current values are determined. Additionally, voltage differences between pairs of actuator coil voltages (corresponding to the current values) and angular velocity differences between pairs of angular velocities are determined. Coil resistance is estimated based on the current differences, the voltage differences and the angular velocity differences. These coil resistance estimates can be useful for accurately estimating actuator coil, actuator arm and/or head velocity.

Abstract: A disc drive includes a transducer having a separate element for writing information and a separate element for reading information to and from the disc. In a disc drive designated to read and write long sequential records, the track misregistration budget is reduced to account for previously written tracks not being encroached on one side. An initial track is written. Subsequent tracks are written after a seek in one direction. The subsequent track is written so that the initially written track is overwritten to one side and leaves a track having a width substantially equal to the width of the read element. Records can be written into data bands of a selected number of tracks. A guard band is left between groups of data bands so that data on tracks in subsequent data bands are not overwritten.

Abstract: A disk device that has displacement of servo signals in the circumference direction and radius direction between a plurality of disks, prevents a drop in performance due to the displacement when the heads are switched. To deal with the displacement in the circumference direction, the sector numbers on the disk are converted by a table for each head. Also the servo gate time is corrected by the table according to the eccentricity of the disk, so the servo signal detection accuracy improves. Also to deal with the displacement in the radius direction, the track numbers on the disk are converted by the table using the difference value based on the reference head.

Abstract: Clock speed of the processor in a hard disk drive is controlled during run time to optimize the trade-off between minimizing power consumption and maximizing performance. Processor clock speed is increased during processing of code more performance critical to the disk drive system, while processor clock speed is reduced when less performance critical code is processed. An example of more critical code where processor clock speed is increased is the code executed by the processor from the start of a servo interrupt until output of resulting servo current command is provided from the processor to the actuator controller. To enable changing processor clock speed, an ASIC containing the disk drive processor is selected which provides the ability to switch clock rates of the processor during processor run time.

Abstract: A disk drive is disclosed comprising a disk having a plurality of tracks, an actuator arm, a head connected to a distal end of the actuator arm, and a voice coil motor (VCM) for rotating the actuator arm about a pivot to actuate the head over the disk. A driving current is applied to the VCM to control the motion of the actuator arm. A back EMF voltage generated by the VCM is detected, and a velocity of the VCM is estimated in response to the back EMF voltage. The estimated VCM velocity is compared to a target velocity in a velocity profile, wherein the velocity profile comprises at least an acceleration component and a coast component. The driving current is adjusted in response to the comparison so that the velocity of the VCM substantially follows the velocity profile.

Abstract: A method of enhancing the thermal stability of gray codes is disclosed. The gray code block in a servo area is recorded with a combination of two different magnetization directions. When the two different magnetization directions are expressed as “+” and “?”, the information “1” is recorded as “++??” or “??++” with the information “0” recorded as “+?+?” or “?+?+”. Since the filter for gray code demodulation is provided with a perpendicular recording mode, the servo area does not use long-wavelength signals that are susceptible to thermal demagnetization. As a result, thermal stability is enhanced.

Abstract: In a disk storage a command controller issues a seek command and transmits it to a seek command manager. A head position controller performs a seek operation. If the head position controller is not busy with the seek operation, the seek command manager transmits the seek command to the head position controller. If the head position controller is busy with the seek operation, the seek command manager queues the seek command in a memory and transmits the seek command to the head position controller after the head position controller has finished the seek operation.

Abstract: A disk drive is disclosed comprising a disk, an actuator arm, a head connected to a distal end of the actuator arm, and a voice coil motor (VCM) for rotating the actuator arm about a pivot to actuate the head over the disk, wherein the VCM rotates the actuator arm into a latched positioned when the disk drive is idle. Disk drive control circuitry unlatches the actuator arm by applying a driving current to the VCM according to an open-loop current profile. The open-loop current profile comprises an acceleration pulse having an acceleration magnitude and an acceleration interval, and a deceleration pulse having a deceleration magnitude and a deceleration interval. The deceleration magnitude is substantially smaller than the acceleration magnitude, and the deceleration interval is substantially longer than the acceleration interval, to thereby attenuate acoustic noise when unlatching the actuator arm.

Abstract: A method for estimating resistance of a DC motor for positioning read/write heads of a data storage disk is provided. The DC motor is controlled in an open-loop voltage mode through a motor controller input with a first signal for compensating positioning of the read/write heads onto the data storage disk. The first signal is generated based upon a position error signal representing a difference between a position of the read/write heads and a center of a track to be read. The method includes monitoring the first signal during a read operation of data being stored on the data storage disk, and estimating the resistance based upon spectral components of the first signal.

Abstract: A servo writer system for a disk drive uses the reader element of a magnetic transducer head in the disk drive to read head position information during servo writing of the disk drive. A positioning system in the servo writer uses both the head position information and actuator position information, as feedback signals to accurately position the transducer during servo writing, resulting in high quality servo tracks.

Abstract: Embodiments of the invention prevent the magnetic head from dropping to the magnetic disk when it is retracted. If the power supply Vcc to the drive is interrupted, a power supply voltage detecting section detects that the power supply to the drive is interrupted. A control section sets switches to the ON state in order to discharge the charged retract capacitor and supply the discharge current to a voice coil. The control section retains the switches in the ON state for a period which is determined based on the discharge period specifying control data stored in a register and the count signal from a counter. A voice coil motor, to which the current is supplied, turns the actuator in the unloading direction to retract the actuator to the ramp.

Abstract: A magnetic disk apparatus comprises an actuator for swinging a magnetic head substantially in the radial direction of a magnetic disk. First and second magnetic bodies, which individually constitute magnetic circuits between the magnetic bodies and a permanent magnet of a VCM, are fixed to the rear end of the actuator. The first magnetic body is pulled by leakage flux from the permanent magnet to return the actuator to a parking position when the actuator is deviated from the parking position. The second magnetic body is caused by the leakage flux to act so as to return the actuator at least to a position in a range such that a tensile force acts on the first magnetic body when the actuator is moved overpassing that range.

Abstract: A head positioning apparatus capable of positioning a head at high speed and with high accuracy is provided. The head positioning apparatus includes a magnetic head, a head supporting mechanism, a coarse actuator, a fine actuator, a head position detection part, a fine movement control system for controlling the fine actuator based on the head position detected by the head position detection part, a head moving distance estimation part estimating the head moving distance representing the distance the magnetic head moves, and the coarse movement control system for controlling the coarse actuator based on the head moving distance estimated by the head moving distance estimation part.

Abstract: An NRRO compensation circuit controls a head position in a disc drive. The circuit has a first frequency circuit providing a first output corresponding to NRRO and a first characteristic sensing circuit that senses the first output and that generates a first control output that adjusts a first NRRO compensation gain. A first control circuit included in the NRRO compensation circuit receives the first control output and the first NRRO compensation gain and provides a first NRRO compensator output.

Abstract: A method of calculating bias compensation values for track seeking, including: setting a reference track, and search tracks disposed between the reference track and an innermost track and between the reference track and an outermost track; calculating bias compensation values usable for compensating for biases operating on a magnetic head while moving the magnetic head a direction from the reference track to one of the outermost track and to the innermost track, and then in another direction from the reference track to other of the one of the innermost track and the outermost track; and making bias compensation curves according to head moving distances using the calculated bias compensation values.

Abstract: A transducer is moved in a seek operation from an initial track to a target track on a disk based on a current command. The current command is regulated based on a location of the transducer and a location of an addressed data block on the disk. The current command may be regulated so that the transducer settles on the target track a predetermined time before the addressed data block reaches the transducer.

Abstract: A perpendicular magnetic recording disk drive is discloses which performs a head positioning control operation effectively against a hard easy transition shift (HETS) phenomenon. In the disk drive, a CPU performs an offset correcting operation in positioning control mode after a seek operation, using an offset value set on the basis of the HETS phenomenon from a memory when data is recorded.

Abstract: Systems are provided for improving servo-demodulation robustness. Multiple occurrences of a SAM pattern are searched for in a single servo wedge. Each detection of the SAM pattern in the servo wedge is charactered as a good SAM detection or a bad SAM detection. If more than one detection of the SAM pattern in the servo wedge are characterized as good SAM detections, one of the detections is selected as the best good SAM detection. Further servo functions can then be performed based on the best good SAM detection.

Abstract: A position information signal pattern is recorded into a recording medium. The position information signal pattern is configured by arranging graphics having a circular shape, a rectangular shape or the like surrounded by a certain closed curve as pattern elements on a plane, and arranging the pattern elements in circumferential and radial directions of a disc so that a phase and a head position establish a proportional relationship in two or more frequency components of a reproduced signal. Position signals of the two frequency components included in the reproduced signal from the position information signal pattern are obtained, and the two position signals are added up with a certain ratio so that a position signal without error is obtained.

Abstract: Improved deceleration control for a disk drive is provided. A deceleration profile is selected based on a present velocity (vi), a present position (xi) and a BEMF constant associated with a voice coil motor (VCM). A control signal is supplied to a VCM driver in an attempt to have a read/write head follow the selected deceleration profile. As new present velocities and new present positions are obtained, these steps are repeated until the seek operation transitions from the deceleration phase to a settle phase. 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: Methods and computer program products for determining accurate estimates of coil resistance are provided. Current differences between pairs of current values are determined. Additionally, voltage differences between pairs of actuator coil voltages (corresponding to the current values) are determined. Coil resistance is estimated based on the current differences and the voltage differences. These coil resistance estimates can be useful for accurately estimating actuator coil, actuator arm and/or head velocity.

Abstract: The CPP structure magnetoresistive head has a structure such that a first lead line is electrically connected to a lead contact portion attached to a lower shield layer the width of which is either equal to or shorter than the maximum length of the lower shield layer in the track direction, or the height of which is either equal to or shorter than the maximum length of the lower shield layer in the stripe height direction. With the structures above, it is possible to prevent that a bump is generated on the upper shield layer by the first lead line, and that a magnetic domain is formed by the bump, which is a cause of noise generation. Further, it is possible to avoid overlapping between the lead line and the upper shield layer.

Abstract: An information recording apparatus for recording content information on an information recording medium includes a main information recording area on which main information to be reproduced is recorded, and a plurality of content information recording areas on which content information to be reproduced to indicate contents of the main information is recorded. The apparatus includes a recording device, a confirming device and a control device. The recording device records the content information on a part of the plurality of content information recording areas. The confirming device confirms a recording result of the content information thus recorded. The control device controls the recording device, only when the recording result is confirmed to be successful, so that content information that is identical with the content information recorded on the part of the content information recording areas can be recorded on the other part of the content information recording areas.

Abstract: A disk drive comprises a controller (70) that calculates a drive signal for positioning a head at a desired track on the basis of a desired track-position signal and a measured head-position signal, and a drive circuit for driving a voice-coil motor. The drive circuit includes a current feedback amplifier (21) and a voltage feedback amplifier (50), which can be selectively used. The controller (70) is provided with a speed limiter for determining a maximum speed limiting the speed of a head. The voltage feedback amplifier of the drive circuit is used when the head-position signal is unstable or otherwise malfunctioning, and the current feedback amplifier of the drive circuit is used when the head-position signal is normal.

Abstract: A perpendicular magnetic recording system is provided which eliminates unwanted side writing to adjacent recording tracks due to the skew angle effect. The system includes a perpendicular magnetic recording head with a write pole that is used to sequentially write to adjacent tracks of a magnetic recording disk. In one embodiment, the write pole is aligned at a compensation angle with respect to the recording tracks which remains greater than zero as the recording head travels in an arc across the disk. When the recording head moves radially inwardly or outwardly across the tracks of the disk, the compensation angle remains greater than zero. Any side writing by the write pole to adjacent tracks is eliminated as the write pole sequentially writes to the next adjacent track. By eliminating the skew angle effect, smaller spacings may be provided between adjacent tracks, thereby increasing data storage densities.

Abstract: An apparatus and method of reading and writing data from and to a data storage device is provided. One method of practicing the present invention comprises placing, or leaving an unused track, row or column adjacent to a medium track containing apparatus information. Another method of practicing the present invention comprises placing, or leaving an unused track, row or column adjacent to both sides of the medium track containing the apparatus information.

Abstract: A disk drive is disclosed comprising a disk, a head, and a voice coil motor (VCM) for actuating the head over the disk. The disk drive executes a rotational position optimization (RPO) algorithm to select a next command to execute relative to an estimated seek time computed for each command in a command queue. A motor capability of the VCM is estimated and used to modify the estimated seek time for each command in the command queue to thereby optimize the RPO algorithm.

Abstract: A disk apparatus includes: an actuator 7; a driver 10; a voltage detector 11 for outputting first voltage signal Ed which is produced in a driving coil 5 of the actuator 7; a voltage signal adjuster 16 for outputting pseudo disturbance signal ur and generating second voltage signal Ed+ from pseudo disturbance signal ur, driving signal u, first voltage signal Ed, and disturbance estimation signal ?dest; a disturbance estimator 12 for estimating the magnitude of disturbance load ?d applied to a magnetic head 2 from driving signal u and second voltage signal Ed+ to output disturbance estimation signal ?dest; a position detector 13 for generating position error signal e which corresponds to a current position of the magnetic head 2; a position controller 14 for generating control signal c from position error signal e; and a corrector 15 for generating driving signal u from disturbance estimation signal ?dest and position control signal c.

Abstract: There is provided a technique for controlling drive of a voice coil motor which can select, with priority for effective reduction, any one of heat generation and EMI noise which are presumed to induce a read/write error and for simultaneously realizing the positioning control of magnetic head with higher accuracy during the tracking operation and the high speed access with shortening of the seek operation period. The magnetic disc storage apparatus introducing this technique is provided with a mode to drive with linear control a coil of the voice coil motor from both terminals and a mode to drive one terminal of coil with linear control and the other terminal with pulse width control. Thereby, the coil is driven in the drive mode of linear control during the tracking operation, while one terminal of coil is driven with linear control and the other terminal with pulse width control during the seek operation.

Abstract: The invention provides magnetic disks with the ability for consecutive tracks to be read or written continuously, removing the traversal of the gap between tracks which degrades bandwidth delivery performance. The invention includes a disk surface formatted with tracks, and sectors within these tracks, which vary in radius. The ending radius of a sector differs significantly from its starting radius. The ending radius of the last sector of one track is very close to the starting radius of its successor track, providing a spiral arrangement of tracks, each possessing a fixed number of sectors, and supporting continuous accessing of successive tracks.

Abstract: Data is written to a hard disk drive using shingled writing principles, i.e., each data track is partially overwritten when an immediately contiguous data track is written. Two or more contiguous data tracks establish a band, and a band may store data from an AV file. Tracks may be written in sequence toward or away from the inside diameter (ID) of the disk, depending on their radial location on the disk and the skew of the write element.

Abstract: A technique for reducing the access time in a storage system having serially accessible media. One or more duplicate copies of data are maintained at different offset locations on serial media. When a request is made to read the data, a determination is made as to which copy of the data—either the original data or one of the duplicate copies—will have the shortest access time for accessing the data. Generally, this would be the data copy that will be closest to the data transducer when the tape is positioned for access, such as a tape cartridge being loaded in a tape drive. Once the tape is ready to be accessed, the tape is positioned to access the copy of the data that is in closest linear proximity with the reading transducer. Thus, the copy of the data having the lowest access latency is chosen to satisfy the particular I/O request.