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: 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. The subset of the multiple tracks being boundary tracks of established zones of a disc. Data representative of the radially-dependent repeatable run-out control components for the subset of the multiple tracks is then stored in a table. The stored data representative of the radially-dependent repeatable run-out control components is utilized to interpolate or extrapolate the radially-dependent repeatable run-out control components for tracks within a zone or outside of the zones for which data is known.

Abstract: A rotational recording apparatus that comprises a shock sensor and that adaptively processes the output of the shock sensor to obtain a feed forward signal, so as to implement a stable operation within a practical range. In a rotational recording apparatus wherein a VCM system having a transfer function (G) and a controller having a transfer function (H) perform feedback, the band of a signal(s) of a shock sensor (S) is limited by a bandpass filter (F), and a resultant signal (f) is employed to obtain the output of an adaptive filter (FIR). A signal (p) that a phase shift filter (P) outputs by shifting the phase of the signal f is employed as a signal to be transmitted to a parameter adaptation algorithm (PAA). Within the limited band, the phase of the phase shift filter P matches the phase of G/(1+GH) within a range of ±90 degrees.

Abstract: Method and apparatus for performing a seek operation to move a data transducing head from an initial track to a destination track on a rotatable recording surface. A servo control circuit operates to sweep the head across the recording surface. Servo data from an intermediary track are transduced to obtain a detected angular position value for the head with respect to the recording surface. When the detected angular position value differs from a predicted angular position value for the head, the servo control circuit initiates an index qualification routine at the conclusion of the seek. The qualification routine involves transducing the servo data from the destination track to verify the accuracy of the predicted angular position value. In this way, the effects of spurious (false) index signals obtained from the servo data transduced during the seek operation are minimized, and unnecessary reinitializations of the servo control circuit are avoided.

Abstract: A position detector generates a position error signal corresponding to a current position of a head, a position controller generates a position control signal from the position error signal, a voltage detector detects a voltage signal generated when driving an actuator by a driver, a disturbance estimator generates a disturbance estimation signal from a driving signal and the voltage signal, and a corrector outputs the driving signal from the disturbance estimation signal and the position control signal. The disturbance estimator includes a comparator which compares the disturbance estimation signal with a voltage signal and which outputs a deviation signal, and an adder which adds a signal obtained by multiplying an integral signal, which is obtained by integrating the deviation signal, by a first coefficient and a signal obtained by multiplying a proportional signal proportional to the deviation signal by a second coefficient, and which generates the disturbance estimation signal.

Abstract: A magnetic storage medium is configured to store data along tracks on a disk-shaped storage medium. A distance between the tracks adjacent to each other in a radius direction of the storage medium is different depending on each position in a radius direction of the storage medium.

Abstract: In a disk storage apparatus, an micro processing unit (MPU) as an upper unit calculates a positional relationship between a head section and storage disks using disk management data indicating the positional relationship of servo information among the storage disks to complete a servo lock based on the result of calculation. The servo lock can thereby be executed at high rate without waiting for a disk controller as a lower unit to complete a servo lock.

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 transducing head positioning system for use with patterned media. The patterned media comprises a plurality of data tracks and grooves. The grooved tracks can be used in connection with electrodes on a slider to create an electrostatic motor for microactuation of the slider.

Abstract: A method of driving an electrical load having a complex electrical impedance, such as a voice-coil motor controlling the position of a read/write head in a data storage disk drive system, comprises providing a voltage-mode driver generating drive signals for the electrical load in response to drive commands. Compensated commands for the voltage-mode driver are generated filtering the drive commands, compensating for a phase shift between electrical quantities delivered to the electrical load. The voltage-mode drive thus emulates a conventional, but more expensive, current-mode drive. In a preferred embodiment, the method comprises estimating characteristic parameters of the electrical load during the operation, and adapting the filtering to the estimated characteristic parameters. The estimation comprises implementing a Kalman filtering algorithm, particularly an extended Kalman filtering.

Abstract: In a device (1) for reading and/or writing information from and on, a track on a medium (2), a read and/or write head (3) can be positioned with a positioning device (5, 20) relative to the medium (2). The read and/or write head (3) comprises a carriage (21) and means (22) for maintaining the reading and/or writing in a scanning point at the track during a transverse positioning of the track relative to the carriage (24). A control circuit (6) is present for controlling the positioning device (5, 20). There is a period of the order to magnitude of one millisecond between the supplying of a control signal to the positioning device (5, 20) at a first point in time based upon which the read and/or write head (3) has to be positioned and the actual start of the movement of the read and/or write head (3). The first point in time is before the point in time at which the maintaining means (22) reach the end of the track that is being read or written at the first point in time.

Abstract: An apparatus and method of measuring a back electromotive force (BEMF) voltage of a disc drive voice coil motor (VCM) is provided in which a temperature of the VCM is obtained. The BEMF voltage of the VCM is computed as a function of the temperature of the VCM.

Abstract: A hard disk drive (HDD) capable of controlling its own internal temperature during testing. A test program embedded in the HDD is run only within a pre-determined optimal test temperature range. The internal temperature of 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: There is disclosed a head positioning control system including a feedforward (FF) control system to compensate a disturbance in a disk drive. This system includes an identification unit which executes parameter identification processing to determine a transfer function of the FF controller as well as a control operation. This identification unit updates a transfer characteristic of the FF controller so as to be adapted to a disturbance fluctuation.

Abstract: By dynamically adjusting the maximum voice coil motor driving current produced by an amplifier in a disc drive, amplifier saturation may be reduced, while still maintaining optimal current to quickly drive the voice coil motor during seek operations. Reducing disc drive saturation, and thus non-linearities in the driving current, increases notch filter performance. As the notch filter is used in the disc drive to remove frequencies from the driving current that tend to cause or excite the mechanical oscillations in the disc drive, increased notch filter performance reduces mechanical oscillations and improves disc drive noise characteristics.

Abstract: A magnetic head is disposed opposite to a magnetic disk having a first recording area capable of facilitating writing information to the magnetic disk when the surrounding temperature is low, and a second recording area capable of surely holding information written to the magnetic disk when the surrounding temperature is high. Information is written to the first recording area when the surrounding temperature is low and is transferred later to the second recording area.

Abstract: A system and method is given for minimizing periodic disturbances in electronic systems. Given the input-output characteristics of the system, the present method identifies and cancels the periodic disturbance. The periodic disturbance parameters are identified through the use of a residual generator. The output of the residual generator is fed into an identifier that estimates disturbance parameters. The compensation filter combines the output of the identifier with a set of pre-computed parameters to form a cancellation signal. This signal is then added to the input of the plant to cancel the periodic disturbance.

Abstract: Methods and computer program products for determining accurate estimates of coil resistance are provided. A voice coil voltage value and a corresponding voice coil current value are determined during a seek operation. Additionally, a velocity of the voice coil is determined based on servo information read from servo wedges of a disk during the seek operation. Coil resistance is estimated based on the voice coil voltage, the voice coil current and the velocity values.

Abstract: Optimizing performance of physical disk drives in a disk array storage device with a plurality of logical volumes is accomplished by accumulating statistics over an interval to select two logical volumes for an exchange. After testing to determine any adverse effect of making that change, the exchange occurs to more evenly distribute the loading on individual physical disk storage devices. One set of statistics, seek time, is obtained by combining estimated disk access information and an interpolated seek time obtained from a template that stores characteristics seek times among different pairs of segments that define a physical disk device independently of a logical volume configuration.

Abstract: A method and apparatus for resolving a “continuity” problem that occurs when modes are switched in the head positioning control process, and a contradiction exists between a short seek and a long seek.

Abstract: Provided are a method, system, and program for initializing a storage device. A pulse response profile is determined for a storage system in response to a series of signals generated to seek to a location in the storage system. A determination is made of a desired response trajectory for the storage system that optimizes seek performance. An adjustment vector is calculated based on the pulse and step response profiles and the desired response trajectory to optimize the pulse response profile. The adjustment vector is stored in the storage device for use during storage device operations to apply to control signals generated to perform one seek operation.

Abstract: A magnetic disk drive has a low power consumption state in which the spindle motor is stopped for reducing the average power consumption when no read or write commands have been received. When a read or write command is received, the spindle motor is started. The time it takes to complete a read command is shorter than that for a write command as measured from the receipt of the read command or write command with the spindle motor stopped in the low power consumption state.

Abstract: A disturbance compensation signal is produced by estimating the magnitude of disturbance acting upon an actuator based on a driving signal and a voltage signal generated when driving the actuator. A control signal is produced by multiplying the disturbance compensation signal by a gain adjustment coefficient. A head position error signal is produced based on the target position of a magnetic head and the current position of the magnetic head that is detected based on servo information recorded in advance on a magnetic disk. A gain adjuster obtains the driving signal by adding together the control signal and a position control signal. The actuator is driven with the driving signal output from the gain adjuster.

Abstract: A magnetic disc storage apparatus including a magnetic head for reading information from a storage track on a magnetic storage disc driven to spin, a voice coil motor for moving the magnetic head above the disc, and a magnetic head drive system for executing a position control of the magnetic head by controlling driving current of the voice coil motor by a feedback control while monitoring a state of reading the magnetic head in which the magnetic head drive system includes multi-mode driving means for executing a linear drive mode for controlling, as an analog amount, the driving current of the voice coil motor when an amount of driving to move the magnetic head is small and executing a pulse drive mode for controlling, as a digital amount, the driving current of the voice coil motor when the amount of driving to move the magnetic head is large.

Abstract: A disk drive is disclosed employing an offset-nulling amplifier for detecting a back EMF voltage of a voice coil motor (VCM) in a velocity mode servo control system. The offset-nulling amplifier comprises a differential amplifier, an input stage for swapping the polarity of the input voltage at a periodic interval, and an output stage comprising a single-ended amplifier having an input switched at the periodic interval between the positive and negative outputs of the differential amplifier.

Abstract: Disclosed is a method of access control for a disk drive whereby an access operation for, particularly, sequentially and alternately executing accesses is supported. A CPU of the present disk drive sequentially and alternately executes accesses to a plurality of data tracks on a disk in response to an access request generated from a host system. During the access operation, the CPU secures time for a look-ahead operation, the time corresponding to the difference between transfer rates. Thus, sequential and alternate access operation in which the number of seek operations can be reduced can be realized.

Abstract: A memory section stores values of the runout component, which are obtained in respective predetermined radial positions on the disk. A determining section selects, from the memory section, a value of the runout component corresponding to a target position. A runout detector uses, as an initial value for adaptive learning, the value of the runout component selected by the determining section, and calculates, by the adaptive learning, a value of the runout component contained in a position error between a head position and the target position. A feedforward controller calculates a feedforward value used to suppress the runout component calculated by the runout detector. A feedback controller calculates a feedback value from the position error. An adder generates, from the feedback value and the feedforward value, a control amount used to position the head in the target position.

Abstract: A position control system for a magnetic head improves servo tracking characteristics in a low frequency range without impairing the stability of seek operations. The position control system is equipped with two integrators: a first integrator 43 and second integrator 45. The gain K3? of the second integrator 45 is set larger than the gain K3 of the first integrator 43. The first integrator 43 plays the role of offsetting the bias force acting on the magnetic head while the second integrator 45 plays the role of improving the servo tracking characteristics in the low frequency range.

Abstract: A method for writing streaming audiovisual data to a disk drive is performed by organizing the data into clusters and commencing writing the clusters to the first physical sector encountered after the read/write head has settled to the desired track on the rotating disk. A cluster contains a number of data blocks corresponding to the number of physical sectors in an integer number of tracks on the disk, so that the writing of a single cluster is the writing to an integer number of full tracks on the disk. Even though the disk drive may have a physical index to identify the first physical sector in all the tracks, the writing of cluster data takes place without regard to index position.

Abstract: The magnetic disk apparatus includes a magnetic disk for storing thereinto information; a head equipped with a recording conversion element for writing information into the magnetic disk and a reproducing conversion element for reading information from the magnetic disk; an actuator arranged by a suspension for supporting the head so as to move the head on the magnetic disk, and also a drive apparatus for driving the suspension; and a stopper for limiting a movable range of the actuator, whereby a distance between a reproduction element and a recording element is measured and also a track width of the magnetic disk is measured in order to execute a self-servo write operation.

Abstract: A magnetic recording disk drive can prevent the deterioration of the head off-track characteristics and the reduction of the drive performance even when an erase band asymmetry resulting from a skew angle exists. A write inhibit slice value for an inner peripheral side offset is made smaller than a write inhibit slice value for an outer peripheral side offset at a position where an erase band on the inner peripheral side is greater than an erase band on the outer peripheral side, so that the adjacent track on the outer peripheral side cannot easily erase a data track. On the contrary, the inner periphery and the outer periphery are paraphrased at a position where the erase band on the outer peripheral side is greater than the erase band on the inner peripheral side.

Abstract: The present invention may be regarded as a disk drive comprising a disk, a head, an actuator arm for actuating the head radially over the disk, and a voice coil motor (VCM) for rotating the actuator arm about a pivot, the VCM comprising a coil comprising a VCM resistance R. A back EMF voltage detector measures a back EMF voltage across the coil, and a current detector detects a current I flowing through the coil. An IR voltage detector, responsive to the current I detected by the current detector, detects an IR voltage proportional to the current I times the VCM resistance R. A voltage compensator substantially cancels the IR voltage from the measured back EMF voltage to generate a compensated back EMF voltage. A control voltage generator, responsive the compensated back EMF voltage, generates a control voltage applied to the coil to generate the current I flowing through the coil.

Abstract: A disk device has eccentric misalignment between a plurality of disk surfaces. In order to prevent transient phenomena due to differences in the eccentric trajectories during head switching, a head position control method performs feed forward control for a plurality of disk surfaces by application of the eccentricity correction current of respective heads, and when switching heads, predicts the velocity fluctuation or current step differential between heads from the eccentricity correction current, and thus corrects the control system to eliminate velocity fluctuation and current step differential.

Abstract: A disk drive is disclosed comprising a voice coil motor (VCM) driver including an H-bridge driver having a first sense resistor connected in series with a supply voltage and a second sense resistor connected in series with ground. First and second amplifiers amplify the voltages across the first and second sense resistors, wherein the output of the amplifiers drive respective first and second oscillators. A counter processes the frequency signals output by the oscillators to generate a digital representation of the current flowing through the voice coil of the VCM.

Abstract: A disk drive is disclosed comprising a voice coil motor (VCM) for actuating a head radially over a disk. A VCM driver comprises first and second transistors forming a common collector amplifier for sensing a current flowing through a voice coil of the VCM. The common collector amplifier improves the accuracy of the current sense measurement when the VCM is driven in a pulse width modulated (PWM) mode.

Abstract: A CPU sets an SPM driver in SPM start-up mode when a SPM is started up. At this time, a voltage selector applies, to a driver circuit, a voltage (high voltage) boosted by a voltage booster. A starter control circuit controls, during the period of an SPM start-up mode, the driver circuit with the high voltage applied thereto, thereby starting up the SPM. After the SPM has been started up, the CPU sets the SPM driver in PWM mode. At this time, the voltage selector switches the voltage applied to the driver circuit, from the boosted voltage to the voltage (low voltage) of a power supply. During the period of the PWM mode, a PWM circuit controls the driver circuit with the low voltage applied thereto, so as to rotate the SPM at a rated speed.

Abstract: An objective of the present invention is to provide a magnetoresistive head with high yield, less in noise and superior in high frequency performance, as a CPP structure magnetoresistive head, which is capable of suppressing a noise caused by a bump on an upper shield layer or a lower shield layer, and reducing capacitance C.

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.

Abstract: Embodiments of the present invention include a method and an apparatus for generating an optimal MRO for a zone having a plurality of tracks. A disc drive controller determines the optimum MRO of a zone of tracks by analyzing multiple tracks in the zone with the actuator arm located at a series of offsets relative to the track center. Selected tracks in the zone are written to once. Then the selected tracks in the zone are sequentially read at a first offset, and the corresponding errors recorded. This reading is repeated for each of the offsets until all offsets have been analyzed. Based on the offset, or band of offsets, with the least errors over the selected tracks, the optimum MRO can be selected for the zone. The process can be repeated for each zone and the optimum MRO values stored in an MRO table in the disc drive for use during subsequent read and write operations.

Abstract: An apparatus and method of measuring a back electromotive force (BEMF) voltage of a disc drive voice coil motor (VCM) is provided in which a temperature of the VCM is obtained. The BEMF voltage of the VCM is computed as a function of the temperature of the VCM.

Abstract: A spindle motor control circuit for controlling a motor; including a control circuit to control the motor during at least a low state, a pulse state and a high state, the motor braking during said low state, the control circuit receiving a flyback voltage from the motor during the pulse state and the control circuit receiving a reduced flyback voltage from the motor during the high state.

Abstract: This invention relates to a head position control method for a disk device that uses a disk medium whose tracks have been formatted externally, and a disk device that effectively uses the range of motion of an actuator. In a disk device that has a disk medium, a head, an actuator, a control circuit, there is a conversion mechanism that sets a data area in the writing range of the disk that corresponds to the range of motion of the actuator, and converts a logical address to a physical address in the data area. This invention makes it possible to set a storage capacity that makes maximum use of the range of motion of the actuator for any device, even when there is a position offset in the range of motion of the actuator.

Abstract: The present invention discloses methods for manufacturing MTJ cell of MRAM wherein the surface of a pinned magnetic layer having a crystalline structure of long range order is physically impacted with heavy ions or atom to form an amorphous layer having a crystalline structure of short range order. In accordance with the method, a metal layer for connection layer and a pinned magnetic layer are formed. A surface of the pinned magnetic layer is physically impacted with atom to form an amorphous layer. A tunneling barrier layer, a free magnetic layer and a MTJ capping layer are sequentially formed and the MTJ capping layer, the free magnetic layer, the tunneling barrier layer, amorphous layer and the pinned magnetic layer are patterned using a MTJ cell mask to form a MTJ cell.

Abstract: Initially, from an off-track position at a known side of, and displaced from, a servo track pattern of a tape subject to lateral movement, servo loop logic slews a tape head servo sensor laterally toward the pattern at a rate greater than the maximum rate of lateral movement of the tape. Upon detecting sensed servo signals, the logic decelerates the slewing rate. Upon detecting that the sensed servo signals are within a lock window tolerance, the logic locks a servo loop to a position error signal representing the current lateral position of the servo sensor, thereby acquiring the servo pattern.

Abstract: A disk drive is disclosed comprising a disk, a head, an actuator arm for actuating the head radially over the disk during a seek operation, and a voice coil motor (VCM) for rotating the actuator arm about a pivot, the VCM comprising a coil comprising a VCM resistance R. A back EMF voltage detector measures a back EMF voltage across the coil, and a current detector detects a current I flowing through the coil. An IR voltage detector, responsive to the current I detected by the current detector, detects an IR voltage proportional to the current I times the VCM resistance R. A voltage compensator substantially cancels the IR voltage from the measured back EMF voltage to generate a compensated back EMF voltage. A control voltage generator, responsive the compensated back EMF voltage, generates a control voltage applied to the coil to generate the current I flowing through the coil. A memory stores a first compensated back EMF voltage generated at a first time period of the seek operation.

Abstract: A controller for a disk drive that accesses a look up table having a plurality of thermally characterized values corresponding to a plurality of seek operations. For each seek operation, the corresponding value is added to a register. The controller decrements the register at a rate that is determined using servo interrupts occurring as a result of the rotation of the disk. When the value of the register exceeds a threshold, the controller adjusts the subsequent seek operation so as to inhibit damage to the voice coil as a result of overheating.

Abstract: A circuit estimates speed of an electromagnetic actuator associated with a reading head of a disk storage unit and a digital controller. The circuit includes first and second supply terminals and an output terminal, with the first supply terminal being connected to the electromagnetic actuator. A measuring resistor is connected to the second supply terminal, and is connected in series with the electromagnetic actuator for measuring a current which passes therethrough when a supply voltage is applied between the first and second supply terminals. An adder has an output connected to the output terminal for providing an output voltage, a first input is connected to the first supply terminal, and a second input is connected to the second supply terminal. An adjustable-gain amplifier is connected between the measuring resistor and the second input of the adder for transferring the supply voltage and a voltage across the measuring resistor to the adder.

Abstract: A disc drive with an information portion previously written on a rotatable disc surface, a servo write clock generator phase lock loop circuit controlling timing for writing a reference mark to the rotatable disc surface in substantial time alignment and phase and frequency coherent with the information portion previously written to the rotatable disc surface, a servo write clock generator phase lock loop circuit controlling timing for writing the reference mark, a pulse detector circuit for creating logic level signals from the reference mark, a pattern generator for generating reference mark write signals from the logic level signals, a memory buffer for storing radial position correction tables and values for writing the reference mark, and a self-servo control and sequencing circuit synchronizing timing signals for writing the reference mark to rotatable disc surface of disc drive.

Abstract: A magnetic disk drive system having a write head Hw and a read head Hr which can move over a magnetic disk in a radial direction of the disk and are arranged at a distance from each other. At a predetermined write start timing tWG, it writes measurement information by the write head in a specific sector at a first timing tW, then reads the information by the read head, detects predetermined positional information included in the information, and produces a second timing tDA. The system subtracts the interval between the second timing and the start timing from the interval between the first timing and second timing to measure the write/read head distance time difference in the track direction of the magnetic head unit. The write/read head distance information is used for correction and control of the operation of the magnetic head unit.

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.