Abstract: A method for determining servo loop gain of a servo loop in a disc drive includes performing a plurality of seek operations, each seek operation moving a head in a disc drive across a plurality of tracks on the disc. Afterwards, the head is settled over a radial position on a track and a signal is injected into the servo loop at the first frequency. At least two values generated by portions of the servo loop are measured to determine a servo loop gain.

Abstract: For low velocity retraction of a disc drive actuator during a parking operation, a system comprising a voltage generator circuit generates a plurality of discrete dc voltage levels, a timing circuit provides a series of timing pulses, and a selection circuit responsive to the voltage generator and timing circuit outputs a voltage profile of increasing voltage steps from the voltage levels and the timing pulses. The voltage profile is provided to a driver circuit that drives a voice coil motor which, in turn, positions the actuator with respect to the discs of the disc drive. The application of the voltage profile during the parking operation causes the driver circuit to act as a voltage source for the voice coil motor. External bias forces upon the actuator tending to force the actuator towards the park position generate a back EMF in the coil, opposing the voltage source of the driver circuit and the motion of the actuator towards the park position.

Abstract: In a head positioning method and device in which the position of position signals between heads is not uniform, it is aimed to reduce the time taken to find the position signals even when heads are switched. The storage disk device comprises a storage disk 1 with the position signal, a plurality of heads 3a through 3d that read the information from recording disk 1, an actuator 5 that moves the heads, and a control circuit 11 that positions the heads based on the position signals read from the recording disk by the selected head. This control circuit 11 comprises a synchronization circuit 6 that, in response to a head switching cue, synchronizes the time of the detection signal for detecting the position signal with the time of the position signal read by the head to which switching is directed, and a processing circuit 11 that reads the position signal for the head in response to the synchronized detection signal and positions the head in response to the position signal read.

Abstract: For a balance adjustment due to a reduction in size and weight of an actuator, an arm portion, an axis attaching portion, and a coil supporting portion are arranged so that the centers of gravity on the coil side are located on a straight line connecting a rotational center and the center of gravity on the head side. Further, the improvement of an assembling efficiency of a VCM, an increase in torque, a one-touch fixing of an FPC connecting band, a noise prevention of a read pattern, and an insulation between the base and cover due to a bias of an MR read head are accomplished. A sector mark is detected by comparing a peak detection pulse and its reference polarity signal. A redundancy is provided to a reference detection polarity signal so that a read signal can be detected even if any one of the read signals of the sector marks is dropped out.

Abstract: A method for positioning a magneto-resistive head onto an head load/unload ramp of a storage unit, the magneto-resistive head disposed upon an actuator arm, the actuator arm also having a voice coil, includes the steps of detecting a reset signal, generating a back electro-motive force voltage with a spindle motor in response to the reset signal, generating a drive voltage in response to the back electro-motive force voltage, using a switching circuit to provide the drive voltage to the voice coil in a first polarity for a first period of time, and thereafter, using the switching circuit to provide the drive voltage to the voice coil in a second polarity.

Abstract: A servo control system for a voice coil motor including a servo controller using position feedback to provide an acceleration current to the voice coil motor and voice coil brake providing a deceleration current based upon velocity feedback from the voice coil motor. In one embodiment, the velocity of the voice coil motor is derived from current feedback. A method for braking an actuator driven by a voice coil motor including the steps or receiving and processing current feedback from the voice coil motor and supplying a deceleration current to the voice coil motor derived from the current feedback from the voice coil motor.

Abstract: Disclosed is a data refresh method for preventing the disappearance of data on a storage medium, and for detecting refresh target data accurately and in a short time. A storage system has a storage medium 6, a head 4, and a control unit 30 for carrying out refresh processing. A refresh operation extracts data that needs to be refreshed by measuring the read-out output level of target data. Then, data requiring the refresh is re-recorded to the storage medium 6 by the head 4. Because an actual data level is observed, it is possible to accurately detect refresh target data, and because there is no need for a reference area, it is possible to prevent a reduction in storage capacity.

Abstract: A method of detecting a position on a disk is applied to a disk which is time-divisionally recorded with a data region and a servo region based on a signal read from the disk, where the servo region is recorded with a servo pattern having a length of consecutive “0”s longer than a length of consecutive “0”s existing in the data region, and the servo pattern has three or more zones with consecutive “0”s. The method includes the steps of (a) digitizing the signal read from the disk and slicing at a predetermined level so as to convert the signal into “0” or “1”, and (b) detecting the servo pattern when two zones with consecutive “0”s are detected from information converted by the step (a).

Abstract: Methods and apparatus for reducing overall seeking acoustics in a head-disk apparatus are disclosed. In accordance with one aspect of the present invention, a method for reducing overall seeking acoustics in a disk drive apparatus, which includes an actuator, involves calculating an error that is a measure of a difference between a desired trajectory for the actuator and an actual trajectory for the actuator, and calculating a preliminary gain. The method also includes determining when the preliminary gain exceeds a minimum acceptable gain limit, and updating a current command using the preliminary gain and the velocity error when the preliminary gain exceeds the minimum acceptable gain limit. The preliminary gain is generally arranged to enable the updated current command to reduce the overall seeking acoustics. The updated current command is sent to a power amplifier which then generates a seek current signal using the power amplifier and the updated current command.

Abstract: In a disk device, in a state where no access to the disk is permitted, instead of permitting the head to be driven stepwise whenever step pulses are fed in, the head is inhibited from being driven stepwise until a predetermined period of time elapses after the disk starts being rotated. This helps reduce electric power consumption in such a state. Moreover, when the head has been retracted to its initial position because of an error in the stepwise driving thereof, instead of waiting for step pulses to be fed in from the host and thereby losing much time before the head is moved back to the track at which it was located before the error, the position of the head before the error is stored so that the head can be, by self recovery, moved back to the position before the error without waiting for an instruction from outside the disk device.

Abstract: A method of filtering the actuator driving energy in a disc drive is provided in which the configuration of a digital notch filter is adapted according to which data head is selected. In one embodiment of the invention, digital notch filter constants corresponding to the resonance frequencies of each individual data head are stored in memory. When a particular data head is selected for reading or writing, the digital notch filter constants corresponding to the selected head are retrieved from memory and provided to a digital notch filter, which filters the driving energy according to the retrieved digital notch filter constants. In addition, a disc drive which implements said method of filtering the actuator driving energy is provided.

Abstract: A contact start/stop architecture for disk drives overcomes problems introduced by low flying MR (magnets resistive) heads and textured landing zones. Takeoff velocity for heads vary from the textured landing zone to the data zone. Contact start/stop operations are controlled relative to a critical takeoff velocity between takeoff velocity in the data zone and takeoff velocity in the landing zone, which critical velocity is less than that required to achieve negligible contact between the head and disk surface while the head is within the landing zone, but greater than takeoff velocity within the data zone. An initial seek from the landing zone begins at critical takeoff velocity. The head drags along the disk surface in the landing zone, since it has not reached takeoff velocity within the landing zone, but will immediately be at fly height as soon as the head reaches the data zone, minimizing the total drag distance of the head in the landing zone.

Abstract: A disk drive with means to prevent accidental landing of a head/slider on the disk surface is described. In one embodiment a shock sensor is provided to sense external shocks received by the mechanism. During loading (positioning) of the actuator bearing the head/slider over the disk, if a shock is sensed, loading is stopped and an immediate unloading is performed to return the actuator to the withdrawn position. In another embodiment the unload operation is performed when the rotational speed of the disk is changed. In another embodiment the unload operation is performed when the rotational speed of the disk drops below a threshold. A circuit and method for detecting when the rotational speed of the disk drops below a threshold is also provided. The unloading in the various embodiments may be performed using velocity control or without velocity control.

Abstract: An actuator circuit includes an H-bridge having sense and power FETs to drive a voice coil motor. A differential amplifier configuration is connected to the H-bridge. A bias circuit connected to the H-bridge and to current sources controls bias current through the one sense FET and one power FET and through the other sense FET and other power FET. A common mode feedback is circuit connected to the voice coil motor to provide common mode feedback to the differential amplifier configuration. The FETs, which may be unmatched, are operated to achieve class AB operation.

Abstract: A recording disk apparatus is provided. The recording disk apparatus includes a recording disk having at least one recording surface with a plurality of spaced recording tracks. The recording disk also includes a positioning arm with a head assembly. The head assembly has a plurality of read transducers. Each consecutive transducer is positioned relative to one another at a distance substantially smaller than a spacing between two consecutive tracks.

Abstract: A direct access storage device (DASD) servo control system includes a servo controller that makes an estimate of disk actuator arm position and velocity as for a regular, expected PES signal sample time, and then alters the estimate for an odd sample time using a simplified estimation function. The altered estimate is generated after determining the amount of time by which the odd sample time is longer than the regular sample time. An odd sample time event is recognized and the odd sample time is forced longer than the regular sample time by skipping a disk control signal computation interval. In this way, the estimated position and velocity of the disk arm is improved for odd sample times, even where the change in one PES sample time may be unrelated to the change in any subsequent PES sample times.

Abstract: A head position signal demodulator that demodulates a position signal indicating the position of the magnetic head in the disk radius direction based on a servo pattern recorded on the magnetic disk includes a waveform shaping circuit which shapes an input signal obtained from the magnetic head according to the servo pattern and a phase comparison circuit which compares a phase of an output signal of the waveform shaping circuit and a phase of a reference signal and outputs a phase difference signal. The head position signal demodulator also includes a position signal generation circuit that generates a position signal of the magnetic head based on the phase difference signal, and a phase shifter which changes the phase of the reference signal during micro jogging, for an amount of the phase which has been set according to the amount of the micro jogging.

Abstract: A multi-task system employs a single interrupt occurring at fixed time intervals to initiate the control functions. The actuator control, servo control and spindle control routines are operated on a priority basis so that if a control function having a high priority is not ready to be executed, the processor immediately performs execution of the next available control function. More particularly, the spindle control process is operated in the foreground with the actuator control and servo control routines operated on an interrupt basis of the spindle control routine. Upon receipt of the interrupt signal, priority is first given to an actuator control routine for execution. Upon completion of the actuator control routine, or if the actuator control is not ready to be executed, access is given to a servo control routine. At the conclusion of the servo control routine, the interrupt exits to the spindle control routine.

Abstract: A disk drive and method of optimizing data access time by selecting a seek profile and/or settle criteria based on a queued or non-queued environment. The disk drive includes an actuator and a servo system, wherein the servo system is directed to move the actuator as a result of an input/output command received from a host by an interface processor. The disk drive may execute the input/output commands in a queued or non-queued environment. The servo system commands the actuator to perform a seek using a seek profile and defines settling criteria for the seek operation. The seek profile includes an acceleration profile and a deceleration profile. The method includes the step of providing a queued seek profile and a queued settling criteria for a seek used to position the actuator to execute a command in a queued environment.

Abstract: A method formats disc surfaces in a disc drive for storage of data in a group of tracks on the disc surfaces. The disc drive performs seek operations to seek among cylinders on the disc surfaces as a function of time according to an actual seek profile. An approximation of the actual seek profile is determined such that the actual seek profile falls within the approximation. The disc surfaces are formatted according to the approximation of the actual seek profile.

Abstract: A system, method, and device for moving a plurality of heads in a disk drive is disclosed. The system comprises hard disks, read/write heads for reading from or writing to the hard disks, a voice coil motor for moving the plurality of heads, a voice coil motor driver for energizing the voice coil motor, a voltage clamp device for regulating a voltage across the voice coil motor, and a park voltage source. The voltage clamp device comprises a transistor, a switch, and a resistive divider network. During head parking, a park voltage source activates the voltage clamp device, which clamps the voltage across the voice coil motor to a fixed value, resulting in movement of the voice coil and heads towards a park location with fixed velocity.

Abstract: Desired data recorded in a recording medium is read as a result of a head scanning a desired track, track tracking information for detecting the amount of displacement of said head with respect to the track and address information for identifying the recorded data are also recorded in said recording medium, and the track tracking information and the address information are used so that the head scans the desired track properly. The recording medium is used in which recording medium the track tracking information and the address information is disposed so that the head first scans the track tracking information and then scans the address information. Whether the track, which the head scans, is the desired track is determined from the address information. The amount of displacement of the head with respect to the track is detected from the track tracking information. The desired data is read from the desired track.

Abstract: A disk drive system includes a servo system for driving mechanical parts, including a read/write head, to a desired track on a disk. The mechanical parts undesirably resonate at a frequency f, where f is a function of a temperature t of those mechanical parts. The servo system includes a notch filter responsive to an indication of temperature t, to attenuate the amplitude of frequency f in a broadband control signal that is applied to move the mechanical parts.

Abstract: A narrow read head and a wider write head are used to store and retrieve data from a storage medium, such as a magnetic disk or tape. The wider write head is selectively positioned to record overlapping data tracks. The read head is subsequently positioned to read the non-overlapping portions of the data tracks. In one format, a read seldom data block is recorded by sequentially recording a plurality of data tracks such that each subsequent data track partially overlaps a previously written data track. In another format, pairs of data tracks are recorded by side-by-side, wherein within each pair of data tracks there is an overlapping region. In either format, the narrower read head is positioned to read the non-overlapping portions of the data tracks. Consequently, the storage capacity of the storage medium is optimized to take advantage of the narrow read head.

Abstract: A disk drive includes a voice coil motor (VCM) and a VCM power source circuit which is coupled to a standard power supply having a fixed voltage. During seek operations the VCM power source circuit provides a boosted voltage, greater than the fixed supply voltage, for the VCM. The VCM power source circuit provides the boosted voltage independently from the back EMF generated in the voice coil motor. The increased VCM voltage allows faster access times and more efficient VCM operation.

Abstract: A method and system for reducing positioning noise in a data storage system are provided. An access device is positioned over a data storage medium using a stream of bursts stored on the medium. The bursts are sensed at a frequency determined by the rate at which the medium is moved relative to a sensing device. Output positioning values are provided to position the access device at a frequency higher than the frequency at which the positioning bursts are sensed, and/or at random times. The random times may be calculated as random advances or delays from time points occurring at a fixed frequency.

Abstract: Apparatus and method for reducing the generation of acoustic noise in a disc drive. A seek is carried out to move a head from an initial track to a destination track on a corresponding disc surface using a servo circuit which outputs a series of current command values indicative of successive magnitudes of current to be applied to an actuator motor. A velocity profile provides a sequence of demand velocities indicative of the desired velocity as the head is decelerated to the destination track. During the seek, open loop current is applied to the actuator motor to accelerate the head away from the initial track, the current command values defining a rising portion wherein the current is successively increased to a first level and a subsequent falling portion wherein the current is successively decreased to a second level, the rising and falling portions each preferably characterized as a one quarter sine wave at a selected frequency.

Abstract: A data storage apparatus includes a servo controller (160) coupled to an actuator (190). The servo controller (160) provides control command signals to the actuator (190) to move a head from an initial position to a final position at a discrete time interval. A method of moving at least one head of a disk drive is also provided. The method includes the step of moving the head from an initial track to a final track without utilizing a separate track acquisition operation to position the head over the final track.