Abstract: A control module for a rotating storage medium includes a data wedge format table (DWFT). The control module also includes a buffer control module that has a DWFT queue that includes X entries from the DWFT and one of X first servo information for each of the X entries. X is a positive integer. A disk formatter module that compares the one of X first servo information with second servo information that is based on a current position of a read/write device in relation to the rotating storage medium.

Abstract: According to one embodiment, there is provided a magnetic recording medium having a data region in which a plurality of recording tracks, each including magnetic dots arrayed in a down-track direction with a pitch p, are formed in a cross-track direction, and a servo region including a preamble in which a plurality of lines of magnetic dots, which are arrayed in a cross-track direction with a pitch p, are formed at equal intervals in the down-track direction.

Abstract: A read channel includes a variable gain amplifier, a low-pass filter, an AGC, an analog-to-digital converter, a frequency synthesizer, a filter, a soft-output detector, an LDPC decoding unit, a synchronizing signal detector, a run-length limited decoding unit, a descrambler, and a first baseline wander corrector. The first baseline wander corrector corrects a baseline variation by a feedforward control.

Abstract: One embodiment in accordance with the invention includes a method. The method can include utilizing a harmonic test on a magnetic disk of a hard disk drive that produces a first result and a second result. A magnetic spacing distance between a transducer head of the hard disk drive and the magnetic disk can be determined utilizing the first result and the second result. A flying height between a head structure of the hard disk drive and a surface of the magnetic disk can be determined utilizing the magnetic spacing distance.

Abstract: The present invention is directed to a method and apparatus for bulk erasure of disk drives. According to the novel invention, one or more relatively small-sized permanent magnets or electromagnets are configured to be brought into close proximity to a particular disk surface of the disk drive and to produce a concentrated magnetic force that erases the disk. Notably, the magnets are sized and configured to create a focused magnetic field, and correspondingly to prevent stray magnetic fields, which could otherwise be harmful to magnetically sensitive components of the disk drive, such as motor magnets. The magnets may be configured to gain access to the disk surface through one or more openings on a covered disk drive, e.g., through an actuator and/or servo track writer opening. The magnets and resultant focused magnetic field may be large enough to offer substantially full radial coverage of the disk, or may be smaller and configured to move (e.g.

Abstract: Systems and techniques relating to interpreting signals on a channel having an asymmetrical signal amplitude response. A signal processor, such as a read channel transceiver device usable in a magnetic recording system, includes an asymmetry correction circuit configured to receive an analog signal and to compensate for asymmetry in the received analog signal, a signal equalizer configured to receive an input signal responsive to an output of the asymmetry correction circuit and to generate an equalized signal, a discrete time sequence detector operable to examine the equalized signal, and a control circuit that provides a coefficient adjustment to the asymmetry correction circuit to affect the asymmetry compensation based on an estimate of non-linearity derived from the equalized signal and an output of the discrete time sequence detector. The estimate can be a least mean squared estimate of the non-linearity in the equalized signal.

Abstract: In the magnetic recording apparatus, a recording layer is formed in a concavo-convex pattern, and recording elements are formed of convex portions of the concavo-convex pattern. Furthermore, the following equation (I) BL?ERL?BL+2×GL??(Equation (I)) is satisfied in each of tracks, where BL represents a length of the recording element in a circumferential direction, GL represents a length of a gap between the recording elements in the circumferential direction, and ERL represents an effective recording length which is a length of an effective recording area ER in the circumferential direction, the effective recording area ER being created on a magnetic recording medium by a heating head and a recording head.

Abstract: In a method for implementing track shape control during a self servo-write process, an error in a targeted path for writing servo data onto a first track of a disk is detected. The error is correlated with a second error for a targeted path in a previously written track of the disk. A correction is generated for a feed-forward signal used to position a writing element which is used to write servo data for a subsequent track of the disk.

Abstract: A write driver circuit includes a first write driver that communicates with a first node of a write head. A first feedback path communicates with a control input and an output of the first write driver. The first feedback path includes a first resistance connected between the output of the first write driver and the control input of the first write driver. A second write driver communicates with a second node of the write head. A second feedback path communicates with a control input and an output of the second write driver. The second feedback path includes a second resistance connected between the output of the second write driver and the control input of the second write driver.

Abstract: A method of setting up a pre-amplifier for a hard disk drive and a hard disk drive incorporating the method. A serial interfacing mode of the pre-amplifier is checked by writing and reading data to/from the pre-amplifier. A chip ID of the pre-amplifier is checked and a vendor of the pre-amplifier is identified using the chip ID. Default values of the pre-amplifier stored in a ROM and adaptive codes of the pre-amplifier are automatically downloaded to a register of a hard-disk controller, simplifying the pre-amplifier installation and reducing errors which may occur during manual installation of the pre-amplifier.

Abstract: A phase interpolator is provided that, in one implementation, includes an output node, a plurality of phase input circuits, and a plurality of switches corresponding to the plurality of phase input circuits. Each phase input circuit is operable to receive a given phase signal. Each switch is in communication with a given phase input circuit and is operable to couple a given phase signal to the output node.

Abstract: Various embodiments of the present invention are generally directed to protecting a device from damage due to an impact event at the conclusion of a free fall condition through the use of a biasing signal that maintains a retention force until the impact event is completed.

Abstract: An apparatus comprises a waveguide, an optical transducer for coupling electromagnetic radiation from the waveguide to a point adjacent to an air bearing surface to heat a portion of a storage medium, and a first wire positioned adjacent to the air bearing surface, wherein current in the wire produces a magnetic field in the heated portion of the storage medium.

Abstract: A system reads data from a magnetic storage media. A read head reads data from the magnetic storage media and produce an analog signal. A variable gain amplifier amplifies the analog signal. An offset adjust module substantially centers the amplified analog signal to a midscale. A Magneto Resistive Asymmetry (MRA) correction module MRA corrects the amplified analog signal. A Continuous Time Filter (CTF) compensation module processes the amplified analog signal. An Analog to Digital Converter (ADC) samples the amplified analog signal based upon a control signal to produce a digital signal. A Disk Lock Clock (DLC) system produces the control signal to the ADC. The control signal is representative of a frequency offset caused by at least one servo wedge rate error. A Finite Impulse Response (FIR) filter module filters the digital signal. A sequence detector processes the digital signal and detects a bit sequence from the digital signal.

Abstract: Embodiments in accordance with the present invention reduce the number of errors caused by the aged deterioration of a heater for adjusting the clearance between a head and a disk. According to one embodiment, a thermal fly height control (TFC) controller executes the measurement of a resistance value of a heater in a predetermined timing. The TFC controller judges whether or not the measured resistance value falls within a predetermined reference range. If the measured resistance value falls within the reference range, the processing ends without performing any other processing. If the measured resistance value goes out of the reference range, the TFC controller executes error handling processing in response to a resistance failure. As one of the error handling processing, the TFC controller notifies the host that the abnormality (resistance failure) has been detected in the resistance value of the TFC heater.

Abstract: Embodiments in accordance with the present invention provide a magnetic disk drive capable of achieving error recovery stably in a simple configuration in the event of thermal asperity (TA) and minimizing the error recovery time required, and a method for controlling the disk drive. According to one embodiment, if TA occurs, a cutoff frequency of a high-pass filter to which a data read signal is input is first increased and a loop gain of a low-order finite impulse response (FIR) filter connected in series to an FIR filter is also increased as high as possible. Next, a Viterbi decoder to which a signal is input from the low-order FIR filter provides feedback to the low-order FIR filter so that an input signal error becomes a minimum. Tap coefficients of the low-order FIR filter are thus optimized.

Abstract: A magnetic recording disk drive uses a disk having pre-patterned servo sectors extending generally radially across the data tracks. The servo sectors include at least two position error signal (PES) bursts or fields. The phases of the PES fields in the servo readback signal are demodulated to generate a PES to control the disk drive actuator for positioning the read/write heads. Each field contains generally radially directed magnetized stripes, with each stripe comprising a plurality of islands forming a zigzag pattern. The stripes have alternating polarity of magnetizations in the along-the-track direction.

Abstract: A magnetic recording disk drive has a disk with pre-patterned nondata servo sectors extending generally radially across the data tracks for use in positioning the read/write heads on the data tracks. The servo sectors include a synchronization pattern of generally radially directed magnetized marks, a first field of generally radially directed magnetized stripes, and a second field of generally radially directed magnetized stripes. Each stripe in each of the two fields comprises a plurality of radially spaced discrete islands, each island having a radial height of approximately Tp, where Tp is the spacing of the track centerlines in the radial direction. In the first field, the islands are centered at a track centerline, and in the second field the islands are centered at the midline between two adjacent track centerlines. The marks and islands are discrete magnetized regions separated by nonmagnetic spaces.

Abstract: Removing magneto-resistive asymmetry (MRA) from a signal is disclosed. Removing MRA includes determining an estimated offset error associated with error due to offset in the signal, determining an estimated signal error associated with error due to offset and MRA in the signal, and removing at least a portion of MRA from the signal based at least in part on the estimated offset error and the estimated signal error.

Abstract: According to one embodiment, there is provided a magnetic disk apparatus having a magnetic disk having magnetic dot lines each including magnetic dots arrayed at equal intervals in a down track direction, and a read/write head which uses a plurality of adjacent magnetic dot lines as one track and sequentially performs read and write on the magnetic dots included in the magnetic dot lines constituting the track, in which the magnetic dots included in each of the magnetic dot lines in each track of the magnetic disk are displaced in the down track direction from the magnetic dots included in the adjacent dot line in the track depending on a possible skew angle between the read/write head and the track so that the magnetic dots are sequentially accessed by the read/write head.