Abstract: The present invention comprises devices and methods for recovering a block of data. In a preferred embodiment, a block erroneously read due to improper read head nonlinearity compensation is recovered with only one re-read attempt. For the first portion of the block read, the rate of nonlinearity compensation adaptation is up-shifted to a rate more than twice the nominal rate. Substantially off of the remainder of the block is then read with a down-shifted compensation. Preparatory steps are also provided for simple ranging, iterative ranging, and otherwise deriving a nonlinearity compensation value from stored data and software implemented by a controller.

Abstract: A method and apparatus for processing a readback signal obtained from a storage medium using a magnetoresistive (MR) element restores a thermal signal component of the signal. A readback signal obtained from the storage medium comprises a thermal component representing a thermal response of the MR element, and may further comprise a magnetic component representing servo or user data. The readback signal is filtered so as to degrade the thermal component of the signal, typically by amplification circuitry exhibiting a highpass filtering behavior. The highpass filtered readback signal is further filtered using a lowpass filter. The filtered signal is sampled, and a sliding window comprising a series of binary values is applied to groups of the signal samples to produce a plurality of signal sample values for each of the signal sample groups.

Abstract: An apparatus and method for extending the service life of an MR element incorporated in a read/write head involves detecting periods of disk drive system inactivity and selectively switching between the heads for purposes of reading servo information during the inactive periods. Switching between heads may involve selecting each of the heads for reading servo information during one or more periods of disk drive system inactivity or selecting each of the heads in sequence during a respective period of system inactivity. Selecting between heads may also involve selecting a head having a minimum of usage, such as a head having an MR element with a minimum of cumulative operational time or energy dissipation relative to other MR elements provided in the disk drive system. Selecting between heads may further include selectively activating each of the heads for reading servo information for a predetermined duration of time during one or more periods of system idleness.

Abstract: Apparatus using information about the extent of errors in sensed data for performing as a control function at least one of adjusting the position of a magnetic head to improve alignment relative to a track and selecting from two or more data signals a data signal having the least amount of errors is shown. The apparatus uses information about the extent of errors to perform a control function for reproducing the data stored in predetermined storage locations in a storage media. The apparatus positions a transducer for sensing from predetermined storage locations stored data containing at least one constraint. The transducer generates a first signal representative of the data containing at least one constraint stored in the sensed data and any errors introduced into the sensed data during the sensing.

Abstract: The invention includes disk drive circuitry, systems, and methods. The disk drive system comprises control circuitry and a disk device. The disk device stores data and transfers an analog signal representing the data. The control circuitry receives the analog signal, converts the analog signal into a digital signal, and transfers the digital signal. The control circuitry includes zero forcing circuitry and an adaptive filter. The zero forcing circuitry produces new coefficients for the adaptive filter. The control circuitry may also include an analog-to-digital converter, detector, decoder, and LMS circuitry. The analog-to-digital converter receives and samples the analog signal to generate a sampled signal. The adaptive filter shapes the sampled signal based on coefficients to produce an equalized signal. The detector detects binary data from the equalized signal, and the decoder decodes the binary data to generate the digital signal.

Abstract: A method and apparatus for processing a magnetic disc prior to assembly of the disc in a disc drive storage assembly includes measuring a physical characteristic of the magnetic disc and encoding an information pattern within the magnetic disc. The information pattern is associated with the measured physical characteristic.

Abstract: An apparatus and method for determining the configuration of a disc drive head-disc assembly (HDA). The HDA includes an array of rotatable discs and an actuator adjacent the discs, with the actuator supporting a maximum number of heads in a fully populated configuration and a reduced number of heads in a depopulated configuration. Each head is disposed at a unique head position. During each spin-up of the disc drive, a servo circuit determines an impedance of a selected head position having a head when the disc drive is fully populated, but not when the disc drive is depopulated. The servo circuit identifies this configuration of the HDA in relation to the determined impedance, and initializes the drive accordingly. The drive then identifies the configuration of the HDA based on the value of the impedance, initializing the drive accordingly.

Abstract: A method reducing data format overhead in a storage device. A sequence detector includes a series of states and a path memory of predetermined length. This method includes steps of writing a predetermined shortened pad pattern at the end of a user data field pattern to a signal-degrading storage medium such as magnetic tape or disk; generating samples during read back of the user data field pattern and the shortened pattern; and, controlling the sequence detector during receipt of pad samples to converge at only one or several predetermined detector states during a convergence sequence. The convergence sequence, and the detector pad are shorter than a sequence needed to traverse the entire length of the path memory. The final state reached during the sequence can be used to provide an accurate estimate of a last user data bit of the user data field pattern.

Abstract: The present invention provides a retract circuit for a disk drive storage device that increases the reliability of a disk drive, and reduces the manufacturing cost. If the power supply of the disk drive is turned off, the retract circuit receives the current due to a back electromotive force from a spindle motor and clips it to a predetermined value or below, and supplies the current equal to or smaller than the predetermined value to the voice coil of a VCM. Then, the VCM drives a carriage, which swings to retract a head slider to the landing area of the disk. If the power is turned off, an FET transistor is turned on, and the current due to the back electromotive force is supplied to the voice coil via the FET transistor, a resistor, and a second FET. If the current due to the back electromotive force exceeds a predetermined value depending on the value of the resistor, two transistors are turned on.

Abstract: Disk formatting pattern methods and apparatus are disclosed. The methods feature forming a magnetic disk format information pattern on magnetic disk media by elevating the temperature of a pattern area and exposing the area to a magnetic field. The magnetic field has a field strength sufficient to alter magnetic properties of the elevated temperature region, but insufficient to substantially alter magnetic properties of disk regions at the disk's ambient temperature. A patterning system is also featured. The system includes a light source assembly, a pattern mask, and a magnetic field source. The light source assembly is arranged to project a light beam toward a surface of a magnetic disk. The pattern mask is arranged in the path of the light beam to produce a pattern image on the disk surface, and the magnetic field source produces a magnetic field at disk surface regions receiving the pattern image.

Abstract: A multi-pattern is formed to have a plurality of read/write elements on a plane. A medium is formed on a single crystal of Si substrate. A motion of the head relative to the medium is made a simple harmonic motion to form linear recorded bits. This allows fabricating a storage system which provides features of small size, high recording density, high transfer rate, and short access time all at once. The recording density accomplished by the small storage system is extremely high, and may be as high as 10 gigabits per square inch.

Abstract: A master information carrier comprises a substrate whose surface has an embossed pattern corresponding to an information signal. At least a surface of the protruding portion of the embossed pattern is made of a ferromagnetic material. A method for writing an information signal into a sheet or disk magnetic record medium with a ferromagnetic thin film or coating is performed by putting the surface of the magnetic record medium into contact with the master information carrier so as to write a magnetized pattern corresponding to the embossed pattern of the master information carrier into the magnetic record medium.

Abstract: A disk drive is connectable to a power supply having a fixed DC voltage. The disk drive includes a voice coil motor and a spindle motor. A DC to DC voltage converter converts the fixed DC voltage to an increased DC voltage greater than the fixed DC voltage. A voice coil motor driver has switching elements which are controllable to supply the increased DC voltage to the voice coil motor. A spindle motor driver has switching elements which are controllable to supply the increased DC voltage to the spindle motor. The increased VCM voltage allows faster access times and more efficient VCM operation. The increased spindle motor voltage allows for more efficient spindle motor operation.

Abstract: In a servo area SA on a track that is empty of data and that lies outside a user data read/write area, to and from which a user data of a floppy disc is written and read, format information FI of the floppy disc is recorded. The format information FI is recorded along with a track number TN in a gray code area GA in the servo area SA. Thereby, the format of the floppy disc can be identified with no identification hole or the like formed in an envelope encasing the floppy disc.

Abstract: There is provided a magnetic recording apparatus capable of carrying out signal reproduction with high accuracy by using a narrow gap head structure corresponding to high recording density. An asymmetric gap structure MR head includes a magnetoresistance element 26 having a magnetoresistance film 24 and a pair of electrodes 25 disposed at the upper side; a reproducing magnetic gap film 23 disposed only at the lower side of the magnetoresistance element 26; a magnetic shielding film 22 disposed so as to make a laminate with the magnetoresistance element 26 through the reproducing magnetic gap film 23; and an insulating film 27 disposed at the upper side of the magnetoresistance element 26. When a signal is read by use of such a reproducing head, the signal of the present bit is read by subtracting a value obtained by multiplying signals of a plurality of previous bits by predetermined coefficients from the present reproduction signal.

Abstract: A disk drive includes a disk defining a multiplicity of sectors. A method of operating the disk drive includes a step of providing a firmware-controlled state machine which can be in any of a plurality of states including an off-line in-progress state. While the state machine is in the off-line in progress state, the drive performs a firmware-controlled scan of the multiplicity of sectors. While performing the firmware-controlled scan, the drive identifies and repairs a marginal sector.

Abstract: A digital servo system for a disk drive provides servo information signal demodulation. The system includes a digital demodulator including a burst signal accumulator that accumulates terms according to respective burst timing intervals to produce a digital, quadrature position error signal (PES). The demodulator also can include a dibit burst filter with synchronous dibit sampling preferably implemented as a Hilbert Transform filter. Alternatively, the demodulator does not include a filter and a squarer and, instead, the squarer comprises a sum-and-squarer that sums the squares of odd and even digitized samples. In another embodiment, the system employs a digital demodulator having a digital squarer that removes any phase component of the digitized servo information signal and includes a burst signal accumulator that accumulates the squared terms according to respective burst timing intervals to produce the PES. The demodulator may include a filter comprising a harmonic notch filter.

Abstract: An apparatus and method for determining the configuration of a disc drive head-disc assembly (HDA). The HDA includes an array of rotatable discs and an actuator adjacent the discs, with the actuator supporting a maximum number of heads in a fully populated configuration and a reduced number of heads in a depopulated configuration. Each head is disposed at a unique head position. A servo circuit determines an impedance of a selected head position having a head when the disc drive is fully populated but not when the disc drive is depopulated. The servo circuit identifies this configuration of the HDA in relation to the determined impedance, and initializes the drive accordingly.

Abstract: A head loading and parking apparatus for a disk drive device is disclosed that is characterized by varying a voice coil current and voltage during a head loading process. The varying voltage nudges read-write heads off of a load ramp and onto the surface of a data storage medium. Peak power is controlled by selectively turning off portions of the electronic system.

Abstract: A disk drive comprising a plurality of recording surfaces and plurality of associated heads is disclosed employing a n-current preamplifier for generating n independently controlled write currents. For example, the n-current preamplifier may be employed during manufacturing of the disk drive to simultaneously write servo sectors to all of the recording surfaces in a “bank servo write” mode. The n-current preamplifier comprises an input for receiving a plurality of current-setting control signals corresponding to the plurality of heads, and a plurality of signal-to-current converters for converting the current-setting control signals into a plurality of write currents for the heads, wherein each write current has a magnitude that is independently controlled by a respective one of the current-setting control signals.