Abstract: Magnetoresistive (MR) bias is dynamically controlled in a tape drive using a processor device. Upon determining head amplitude is below a threshold value, the MR bias is adjusted for increasing the head amplitude and extending the useful life span of the tape drive.

Abstract: A method and system for estimating a zero gain start (ZGS) bias in a read channel is disclosed. The method may include: receiving preamble samples within a fixed-length window selected for ZGS calculation; calculating an energy associated with a 2T frequency in the preamble samples; calculating an energy associated with non-2T frequencies in the preamble samples; and calculating the ZGS bias based on the energy associated with the 2T frequency in the preamble samples and the energy associated with non-2T frequencies in the preamble samples.

Abstract: A magnetic tape drive has a drive system to move a magnetic tape longitudinally; servo head(s) for reading servo band information from a magnetic tape as the magnetic tape is moved longitudinally; a magnetic tape read write head configured to read and to write the magnetic tape, having a data write width (w) greater than a normal shingled track pitch width (p) of the magnetic tape; an actuator system for positioning the read write head laterally; and a control. The magnetic tape drive stores an overwrite erase format of non-shingled track pitch longitudinal pattern(s) whose pitch is greater than the normal shingled track pitch width (p); and, the control, in response to activation of overwrite erasure of the tape drive, operates the actuator system and the magnetic tape read write head to write non-data to magnetic tape in the stored overwrite erase format.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing circuit is disclosed that includes a data detector circuit and a bias calculation circuit. The data detector circuit is operable to apply a data detection algorithm to a first data set to yield a first series of soft decision data, and to apply the data detection algorithm to a second data set to yield a second series of soft decision data. The bias calculation circuit operable to calculate a series of bias values based at least in part on the first series of soft decision data and the second series of soft decision data. The series of bias values correspond to a conversion between the first series of soft decision data and the second series of soft decision data.

Abstract: A circuit for use with a memory storage device including a magnetic storage medium and a write head operative to subject the magnetic storage medium to a magnetic field in response to an application of current to the write head, includes a write circuit operative to generate a write current supplied to the write head. The write current is characterized by a current waveform that reverses polarity in accordance with data to be stored on the magnetic medium. The circuit for use with the memory storage device further includes a degauss circuit operative to generate a degaussing current supplied to the write head. The degaussing current is characterized by a current waveform that oscillates between opposite polarities with an amplitude and a frequency that change over time.

Abstract: Method and apparatus for detecting head disk interference (HDI). In accordance with some embodiments, a bias calibration circuit is adapted to respectively bypass or amplify a head disk interference (HDI) signal output from an HDI sensor responsive to a bias voltage adjusted according to a first control signal. A detection circuit is adapted to compare a swing range of a signal output from the bias calibration circuit and a swing range of a reference signal, and to output the first control signal responsive to said comparison.

Abstract: Approaches for inducing a magnetic bias in a magnetic recording disk. A biasing apparatus comprises a soft magnetic material member having a shape comprising two opposing recesses, denoted an upper recess and a lower recess. A first magnet is disposed within the upper recess and a second magnet disposed within the lower recess. An air gap exists between the first magnet and the second magnet. An opening in the soft magnetic material member is sized to accommodate at least a portion of the magnetic recording disk between the first magnet and the second magnet. The magnetic field produced by both the first magnetic and the second magnetic flows (a) in the same direction, and (b) perpendicular to the plane of the magnetic recording disk. Using this approach, magnetic material on the disk, such as magnetic islands of a bit pattern media, may be erased and polarized in the same direction.

Abstract: According to one embodiment, a magnetic disk drive comprises a write count memory, a read offset setting module and a controller. The write count memory stores a write count for each track or for each zone on a disk. The read offset setting module sets, in accordance with a write count for an adjacent track to a target track or for a zone to which the adjacent track belongs, an offset from a predetermined position on the target track in a read position in which a head is to be positioned when the head is positioned on the target track for data read. The write count is stored in the write count memory. The controller positions the head in a position shifted from the predetermined position by the set offset.

Abstract: To manufacture a perpendicular magnetic recording-type magnetic tape having a servo signal written therein by a write head having a magnetic gap, a perpendicular direct-current erasing step in which a magnetic tape is magnetized in one direction that is one of two opposite thickness directions of the magnetic tape is performed before a signal writing step in which a servo signal is written in the magnetic tape by outputting a pulsed signal to the write head.

Abstract: Disclosed are a method and system for distinguishing spatial and thermal defects on perpendicular media. The magnetic domains of the perpendicular media are oriented to have a first polarity, scanned using a read head, oriented to have a second polarity and scanned again. The signals from the read head are combined to produce output signals having improved signal to noise ratios from which the locations of spatial and thermal defects can be identified and distinguished.

Abstract: According to one embodiment, a magnetic disk drive includes a grouping module and a refresh controller. The grouping module partitions a set of tracks on a disk into a plurality of groups. Each of the plurality of groups includes a plurality of tracks including at least two tracks with nonconsecutive physical positions. The refresh controller controls refresh process for each of the plurality of groups.

Abstract: A structure for erasure of magnetic media in a hard drive includes a main field pole magnet polarized in a direction toward a drive spindle motor in the hard drive. At least two quadrature magnets are disposed adjacent the main field pole magnet and polarized in a direction toward the main field pole magnet. The main field pole magnet and the at least two quadrature magnets are shaped to provide a slot for insertion of the magnetic media. At least two inverse polarity magnets are disposed on portions of the main pole and quadrature magnets forming the slot. The inverse polarity magnets are polarized in a direction opposed to the direction of the main field pole magnet.

Abstract: A device for setting a bias for a magneto-resistive (MR) head can include a counter configured to provide a count value that varies incrementally from a first count value to a maximum count value. Logic is configured to determine at least one of whether the bias for the MR head has reached a predetermined threshold and whether the counter has reached the maximum count value. The logic provides a bias output signal corresponding to the count value for setting the bias of the MR head according to the determination by the logic.

Abstract: An apparatus, system, and method are disclosed for dynamically controlling a recording head substrate bias voltage. The apparatus includes a midpoint module and a substrate module. The midpoint module calculates a midpoint voltage of a plurality of data read elements and servo read elements contained in the head. The substrate module calculates a substrate bias voltage. The apparatus, system, and method dynamically control the substrate bias voltage post-assembly, minimizing certain head degradations and extending the life of associated head readers.

Abstract: A method for erasing a disk of a hard disk drive. The method includes moving the hard disk drive adjacent to an erasure head that emanates a magnetic field. The magnetic field and moving hard disk drive cause a disk of the hard disk drive to spin under a Lorentz force created by the magnetic field and moving disk. The magnetic field is applied by the erasure head for a duration that causes erasure of the entire disk. The spindle motor is not activated during the entire process. Not activating the spindle motor eliminates any Faraday coupling from the erasure head into the motor.

Abstract: A recording system employing a magneto-resistive (MR) element senses a resistance value of the MR element and generates one or more MR resistance (MRR) signal values based on the sensed MR element resistance value. The MRR signal values might be, for example, current or voltage values proportional or inversely proportional to the MR element resistance value. The MRR signal values might be employed to control one or more of: i) a unity gain bandwidth of a bias loop for the MR element, ii) an MR read head preamplifier low corner frequency, and iii) a slew rate across the MR element.

Abstract: A magnetic data eraser includes a power supply circuit, a receptacle for accommodating a magnetic recording medium or a device incorporating a magnetic recording medium, primary and secondary coils wound around an outer periphery of the receptacle. The primary coil is connected to the power supply circuit. The secondary coil is short-circuited. Excitation of the primary coil through energization by the power supply circuit generates an induced current in the secondary coil, thereby making an interaction between the primary and secondary coils. The interaction generates an alternating magnetic field, whereby the magnetic recording medium is degaussed, so as to erase magnetic data recorded in the medium.