Abstract: A high bandwidth, large stroke spin-stand for testing components of a disc drive includes a coarse positioning stage and a rotary micropositioning stage. The spin-stand is capable of positioning a transducer head relative to the data storage disc based on one or both of: (1) an angular position of a rotary actuator arm in the rotary micropositioning stage; and (2) servo data read from the data storage disc. The angular position of the rotary actuator arm is detected by an encoder. In one embodiment, position adjustments are based on the detected angular position. In another embodiment, position adjustments are based on servo data read from the data storage disc, but are also conditional on angular position being consistent with the servo data. In yet another embodiment, both angular position and servo data from a track are linearized to generate PES adjustment parameters that are recorded on the data storage disc to redefine the track as more circular or to linearize the PES.

Abstract: A method and apparatus for reducing the effects of non-repeatable runout (NRRO) in the estimation of repeatable runout (RRO) in a disc drive is disclosed. PES information is a acquired in a way that leads to randomization of the phase of the NRRO, thereby decreasing the number of revolutions required to estimate the true RRO. A number of RRO estimation measurements are taken over a number of non-consecutive disc revolutions that are spaced in time. In one embodiment, one revolution of RRO data is collected from each head before collecting a second revolution of RRO data from any of the heads. In another embodiment, RRO estimation is concurrent with media certification, such that PES data is obtained while the head is in the write position and writes a track of data for media certification. Similarly, PES data for the read position is obtained while concurrently reading back the written data.

Abstract: Track pitch for writing tracks on a disk is determined based on an available stroke across the disk. The available stroke is identified by searching across the disk for where information can be written and read. The track pitch is determined for writing tracks on the disk based on the available stroke across the disk. Tracks are written on the disk based on the determined track pitch.

Abstract: Read positioning method includes adjusting at least one read head position when accessing read track on at least one rotating disk surface based upon Burst Correction Value of nearest write track, when PES burst patterns of read track and nearest write track match. Apparatus supporting read positioning method may include means for at least partly performing each step. At least one means may include at least one instance of at least one of following: computer, finite state machine, neural network and inferential engine. At least one read method for the hard disk drive included. These read methods may be used during initialization and/or normal hard disk drive operation. Hard disk drive may include servo controller driving voice coil actuator and, preferably further driving micro-actuator. The hard disk drive may include more than one rotating disk surface and more than one rotating disk surface.

Abstract: Methods, servo controllers, disk drives, and computer program products are provided for adapting compensation for repeatable runout (RRO) of sectors of a disk in a disk drive. RRO of a plurality of sectors of the disk is compensated. A status of whether the RRO compensation has been adapted is tracked for at least some of the sectors of the disk, and corresponding records are formed based on the statuses. The RRO compensation of the tracked sectors is selectively adapted or not adapted based on the records.

Abstract: A positioning device includes a swiveling shaft, at one end of which an element to be positioned may be attached, a swivel drive, made up of a rotor, which is movable relative to a stator, a position measuring device, made up of two parts movable relative to each other, and a roller bearing, which includes several rolling elements. The rotor of the swivel drive and a first part of the position measuring device are connected to the shaft in a rotatably fixed manner. The rolling elements are made of a ceramic material.

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: Disk drives, methods, and computer program products are provided for controlling seeking of a transducer that is adjacent to a rotatable data storage disk in a disk drive. The disk drive includes a secondary actuator for positioning the transducer over a second range of movement, and a primary actuator for positioning the secondary actuator over a first range of movement that is larger than the second range of movement. The secondary actuator is controlled to move the transducer toward a target track on the disk while seeking. The primary actuator is controlled to move the secondary actuator toward the target track while simultaneously controlling the secondary actuator to maintain the transducer on the target track.

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: 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: A disk drive is disclosed comprising a microprocessor and a power driver for generating at least one actuator signal applied to the VCM actuator, wherein a serial communication circuit is used to communicate with the power driver. At least one control component periodically generates a control signal, wherein the control signal is transmitted at a substantially constant periodic interval using the serial communication circuit, and a timer times the periodic interval. A job queue controller queues and arbitrates serial communication requests to access the power driver using the serial communication circuit. The serial communication requests include a request to transmit the control signal and requests generated by the microprocessor. The job queue controller services a communication request generated by the microprocessor if the communication request can be serviced before the timer expires.

Abstract: In a tape having separate servo bands of patterns positioned laterally across the tape, the patterns of a separate servo band have at least one differentiating characteristic with respect to patterns of another of the separate servo bands. The differentiating characteristic allows identification of the separate servo bands. For example, the patterns of a separate servo band have differing azimuthal orientations of detectable transitions with respect to another servo band, such as being laterally inverted. In another, variations in the width of gaps of patterns are made with respect to another servo band. In another, variations are made in the number of the detectable transitions of patterns with respect to the patterns of another servo band.

Abstract: A positioning driver (32) for a voice coil motor (22) in a disk drive system (10) is disclosed. Pulse-width-modulated prestage drivers (46) are coupled to power transistors (50) arranged in an “H” bridge for driving the voice coil motor (22), biased with a power supply voltage (VM). The pulse-width-modulated prestage drivers (46) drive the power transistors (50) according to a comparison between an error signal from an error amplifier (36) and a ramp clock signal (RMP) generated by a ramp clock generator (46). The ramp clock generator (46) includes a control circuit (68) that modulates the high and low limits of the ramp clock signal (RMP) in response to variations in the power supply voltage (VM). This modulation of the high and low limits compensates for variations in the gain of the power transistors (50) resulting from variations in the power supply voltage (VM).

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: Track mis-registration (TMR) correction is conditionally made in a hard disk drive using servo data in a closed loop servo control scheme, along with one or more alternative sensing schemes when an external shock or vibration occurs. The alternative sensing schemes include measurement of spindle motor speed using a frequency of servo markers read from a rotating disk, voice control motor (VCM) back emf, spindle motor speed back emf, and accelerometer readings. The predicted TMR resulting from the signal generated by the alternative sensing scheme(s) is simulated based upon a model of the disk drive system, and corrections are applied only if the expected TMR due to the disturbances is large enough that application of the corrections using the alternative sensing scheme would be likely to reduce the overall TMR.

Abstract: A magnetic disk apparatus and a servo pattern recording method therefor, enabling writing of servo signal with high quality, without being affected with ill influences due to fluctuation on a rotation speed when conducting the self servo write operation, comprises: a magnetic disk 102; a head 103 having a write element for use of recording information onto the magnetic disk and a read element for reproducing information from the magnetic disk; and an actuator for moving said head to a desired radial position on the magnetic disk, wherein on the magnetic disk is recorded servo patterns 110 for positioning the head on a recording surface thereof, and within each of the servo patterns are recorded, a pattern sector marker 208a as a marker for detecting passage time of the head, a track ID code 209, and a burst pattern 210 for use of detection of the radial position of the head, following a preamble 207a for use of synchronization of time-base circuit, and further recorded and disposed a second preamble 207b and

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 servo control circuit provides seamless transition between seek and track modes while enabling both rapid seek mode operation and accurate tracking. The control circuit includes an analog-to-digital converter having a non-linear characteristic. The non-linear characteristic provides disproportionately large control voltages to derive speed and settling in the seek mode and essentially linear control voltages in the track mode to provide low noise and accurate tracking operation.

Abstract: An apparatus and method for improving servo loop performance in a disc drive storage system are provided. The servo loop includes a voice coil motor actuator that moves the head in response to a received servo control signal. A sensor, located in the head, senses servo information located on the disc and produces a servo signal therefrom. The servo signal is combined with a reference signal to produce a position error signal. A servo controller receives the position error signal and responsively produces the servo control signal. The servo controller includes a drive signal generator that receives the position error signal and responsively produces a driving energy signal. A vibration damping circuit receives the driving energy signal and responsively produces the servo control signal.

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: An apparatus, system, and method are disclosed for accessing discontinuous media tracks. The apparatus, in one embodiment, accesses discontinuous media tracks of a storage medium having one or more independently formed storage regions thereon. Each storage region may include a set of track segments. A memory may be provided to store track offset information for each storage region. A mapping module may collect track offset information, calculate a physical offset between adjacent storage regions, define a track, create a table, and store the track offset information in the memory. The apparatus may further include a tracking module to sense a position of a head relative to a centerline of a track segment within a current storage region, access offset information, and align a storage head with a closely aligned track segment within a subsequent storage region. Consequently, discontinuous media tracks may be accessed by a storage access device.

Abstract: A disk drive has timing marks (TMs) on the disk, that are chosen to reduce the probability of misidentification of a TM in the presence of read errors. The disk drive searches for TMs within a fixed TM search window which extends past the TM on the disk. A TM preferably maximizes the post-shift sliding distance for m post-shifts of the TM pattern, where m corresponds to the TM search window boundary. In this manner, the probability of a misidentification of the TM due to a post-shift having a small distance from the TM pattern is reduced. The TM pattern also provides pre-shift error resistance.

Abstract: A method and system for providing programmable self-testing of a data storage device comprises selecting one or more host programmable tests stored in memory in the data storage device by setting data in a first log in memory of the data storage device. Parameters for execution of the one or more host programmable tests are set by setting one or more values in a second log in memory of the data storage device. The one or more host programmable tests on the data storage device are then executed. Results of the one or more host programmable tests are stored in a third log in memory of the data storage device.

Abstract: A positioner (20) for a disk drive (10) that includes a magnet assembly (52), a conductor assembly (54), and a control system (22) is provided herein. The magnet assembly (52) includes a pair of magnet arrays (56A) (56B) and a pair of spaced apart flux return plates (75A) (75B). The conductor assembly (54) includes at least a first coil array (80) and a second coil array (82) that are substantially co-planar. The control system (22) directs current to electrically excite the coil arrays (80) (82) to maintain a data transducer (50) on a target track (32) of a storage disk (28).

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 useful to change a system's output from one value to another within a prescribed time-interval in an optimal manner using optimization criteria such as minimal time (e.g., to increase throughput) or minimal energy (e.g., to reduce heat dissipation and reduce induced vibrations). Optimal design of maneuvers (such as fast seek and scanning) that rapidly change the output from one value to another, arise in flexible structure applications, including rapidly positioning the end-point of large-scale space manipulators, positioning of read/write heads of disk-drive servo systems, which are relatively medium-scale flexible structures, and nano-scale positioning and manipulation using relatively small-scale piezo actuators. Maintaining a position of an element constant outside of the transition time-interval is critical in many applications.

Abstract: The invention applies to servo controllers for at least the voice coil motor of a hard disk drive. Today, many control algorithms require 80 to 90 percent of the sampling period to complete their calculation of the next control, making computation time delay no longer negligible. The invention accommodates the transport delay, such as computation time delay, into the state estimator and into the whole control system. Experimental results using a commercial hard drive, as well as simulation results, show that the invention's method effectively improves the hard disk drive control system stability by increasing the phase margin and gain margin. The invention includes the method of operating the servo-controller, as well as the apparatus implementing that method. The invention also includes hard disk drives containing servo-controllers implementing the method, and program systems residing in accessibly coupled memory to a computer within the servo controller implementing the method.

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

Abstract: 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: A magnetic data embedding system (or disk servo writer) includes a stack with a master disk (3) and a plurality of magnetic disks (4) mounted on a shaft of a spindle motor (6), and a rotary positioner (11) which integrally holds one or more read-only heads (71 to 74) for reading the master disk and a plurality of groups of servo heads (101 to 104) and which simultaneously turns both of the kinds of heads. The groups of servo heads have access to the top and bottom sides of the magnetic disks. The servo heads are made carry out writing to the same (top or bottom) side of each of the disks in parallel, within assigned track ranges for the respective servo heads.

Abstract: An apparatus and method for removing mechanical resonance in a disc drive using an adaptive notch filter. Mechanical resonance harmful to a system is removed by a notch filter that adaptively varies the frequency characteristics of the filter with respect to the mechanical resonance frequency existing in the system.

Abstract: A shared state controller is provided that optimizes for settle, rotational vibration, and track following. The shared state controller uses the same state update equation with different output equations for settle and track follow. Two or more different track follow output equations may also be used. Switching logic determines which output equation to use in the controller. The shared state controller switches between a settle controller and a track follow controller based on the state of the actuator. In addition, the shared state controller may also switch between two or more track follow controllers based upon other parameters.

Abstract: A disk drive includes a data storage disk, a transducer, a micro actuator, a coarse actuator, and a controller. The micro actuator is configured to position the transducer relative to the disk over a first range of movement. The coarse actuator is configured to position the micro actuator relative to the disk over a second range of movement that is larger than the first range of movement. The controller is configured to control positioning of the transducer by the coarse actuator and the micro actuator in a track following operation, and in a seek operation responsive to a seek command. The controller is also configured to calibrate its positioning of the transducer by the micro actuator responsive to receipt of the seek command and prior to seeking the transducer from an initial track to a target track.

Abstract: A sinusoidal signal is added to the notch filtered micro-actuator control signal stimulating the micro-actuator. The voice coil control signal is notch filtered to remove the frequency component of the sinusoidal signal before it stimulates the voice coil motor. The micro-actuator control signal is notch filtered to remove the frequency component of the sinusoidal signal before it stimulates the micro-actuator. The response of the system is measured as the Position Error Signal (PES), for the magnetic head moved by the micro-actuator. The measured PES is then demodulated at the frequency of the sinusoidal signal to create a measured amplitude. The stroke sensitivity is then calculated from the measured amplitude and amplitude of the sinusoidal stimulus. The frequency of the sinusoidal signal and notch filters is essentially the same, chosen away from significant excitation frequencies and outside the bandwidth of the servo system.

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: The invention operates two control paths. The micro-actuator control stimulates the micro-actuator. The voice coil motor control path includes the voice coil motor control generating a voice coil control signal, notch filtered to remove at least one significant excitation resonance for a notch filtered voice coil control signal. Amplifying the notch filtered voice coil control signal by a tuning gain stimulates the voice coil motor. A decoupling feedback filter uses the micro-actuator control signal to create a decoupling feedback signal used to decouple the two control paths. A track following command, with PES removed, directs the micro-actuator control. The voice coil motor control is directed by the track following command, with both PES and decoupling feedback signal removed. Preferably, the servo-controller digitally supports the elements of the invention. Implementing the method may preferably include the servo-controller program system residing in an accessibly coupled memory.

Abstract: There is provided a head control method controlling move of a head on a discoidal recording medium including the steps of: partitioning the discoidal recording medium which has position information recorded thereon at radially equal spacing into a plurality of zones; and demodulating the position information using a coefficient set for each of the zones.

Abstract: A method and system control the flight height of a transducer element of a slider mechanism operating in association with a storage disk. The invention adjusts the flight height of transducer element to a first flight height using an electromechanical control mechanism. The flight height of transducer element then achieves a second flight height using a thermal control mechanism. The thermal control mechanism is associated with a thermally responsive portion of transducer element. By heating the thermally responsive portion, a portion of transducer element becomes sufficiently proximate to the storage disk for the transducer element to respond to physical forces arising from electrostatic induction between transducer element and the storage disk. Flight height adjustment of transducer element from the second flight height to a third flight height may then occur using an electrostatic control mechanism which generates a physical force through electrostatic induction.

Abstract: A head positioning system includes: a positioning mechanism section 1 for positioning a head 12; a position controller 2 for detecting a head position signal x to output a position control signal Ux; a velocity detector 3 for detecting the relative velocity of the head 12 with respect to a disk 7 based on the head position signal x; a counter electromotive voltage detector 4 for outputting an estimated head velocity signal Ve2 that is obtained by estimating the absolute velocity of the head 12 based on a counter electromotive voltage signal Vs of an actuator 50; an estimated velocity corrector 5 for correcting an estimation error of the estimated head velocity signal Ve2 based on a velocity signal detected from the head position signal x so as to output a corrected estimated velocity signal Ve2?; and an estimation controller 6 for outputting a velocity control signal Uv based on the corrected estimated velocity signal Ve2?, wherein the actuator 50 is controlled by a control amount signal U that is obtained by

Abstract: A method for algorithmically determining, based on the number of screws used to hold the disks of a disk drive, harmonics of repeatable runout error during disk drive operation, such that correction of the error by feed forward techniques is facilitated.

Abstract: A dual-mode positioning driver for a voice coil motor in a disk drive system is disclosed. Linear prestage drivers and pulse-width-modulated prestage drivers are both coupled to power transistors arranged in an “H” bridge for driving the voice coil motor. The positioning driver is thus operable to drive the power transistors in either a linear mode or a pulse-width-modulated class D mode. In a transition period while switching from the pulse-width-modulated mode to linear mode, comparators compare the phase voltages in the “H” bridge with a reference voltage. The outputs of the comparators are applied to the PWM output amplifiers to drive the power transistors, so that the phase voltages are preconditioned toward their linear bias points. Discontinuities in the drive current through the voice coil motor are minimized as a result.

Abstract: A method of testing a performance of the HGA has a step of writing information from the at least one thin-film magnetic head element onto a magnetic disk with driving the actuator for displacement by applying an alternating drive signal to the actuator, a step of reading out the information of at least one rotation of the magnetic disk by the at least one thin-film magnetic head element without driving the actuator for displacement, a step of storing the information read-out from the magnetic disk as a read-out information along a disk-rotating direction, a step of moving the HGA toward an off-track direction by a predetermined distance, a step of repeatedly executing the reading, storing and moving steps to obtain two-dimensional read-out information along the disk-rotating direction and the off-track direction, and a step of determining, from the two-dimensional read-out information, an off-track position where the read-out information becomes maximum at each position along the disk-rotating direction, the

Abstract: A servo channel digitally processes the data read from a magnetic media. The channel uses both edges of a system clock to detect peaks and generates position error systems by an area-based automatic gear control loop. By altering the sample delay, the channel digitally, up-samples at higher rates without requiring a higher system clock.

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: An actuator arm assembly has an actuator arm and an actuator for moving the actuator arm whereby the arm assembly experiences vibrations. The actuator has a body with a recess formed therein, and a strain sensor is fitted essentially inside the recess such that the sensor generates signals correlated to the vibrations. This arrangement produces a high gain boost from the strain based sensor, making an amplifier circuit unnecessary. The sensor signals are used to damp the vibrations.

Abstract: A data recording medium, such as a magnetic recording hard disk, has data tracks with pseudo-random binary sequences for the servo information used to control the position of the recording head in the disk drive. A first pseudo-random binary sequence (PRBS) and a second PRBS identical to the first PRBS but shifted by a portion of the period of the first PRBS are located between the track boundaries in alternating tracks in a first region of the servo pattern and between the track centers in alternating tracks in a second region spaced along the track from said first region. A servo decoder in the disk drive has two correlators, one for each PRBS. Each correlator outputs a dipulse when its PRBS repeats. The difference in amplitude of the dipulses represents the head position signal. The dipulses also control the amplifier for the signal read back by the head and the timing of the track identification (TID) detector.

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: A digital servo system of an optical disk drive with a calibrated inverse non-linearity function is disclosed. A look-up table is determined, for example, with a focus error signal gain corresponding with a focus error signal offset so that the response of the focus servo system is substantially linear. Additionally, the look-up table can include tracking error signal gain, tracking error signal offset, or tracking loop gain parameters corresponding with the focus error signal offset.

Abstract: A data storage device includes an enclosure case and a circuit board attached to an outer surface of the enclosure case, the enclosure case containing a spindle motor and a circular movement actuator, the spindle motor being for rotating a storage medium, the circular movement actuator being for controlling a position of a read and write head for reading data from the storage medium and for writing data to the storage medium, the circuit board having an interface cable connector at one end portion thereof for establishing a connection to a host. The circuit board is located between the interface cable connector and the spindle motor, and is attached to the enclosure case by use of a plurality of fastening members. An acceleration sensor is attached to the circuit board next to the fastening members for detecting vibrations applied to the data storage device in a rotation direction in a plane along the circuit board.