Abstract: According to one embodiment, an apparatus for controlling a head includes a transmitting module and a controller. The transmitting module is configured to transmit a write signal to a magnetic head having a spin torque oscillator at the time of recording data. The controller is configured to supply a drive signal that has a level higher than the ordinary level for a prescribed effective time, to the spin-torque oscillator in response to an input write gate that instructs the recording of data. During a period other than prescribed effective time, the controller supplies a drive signal having the ordinary level to the spin-torque oscillator.

Abstract: A combined bulk thermal-assister and bulk eraser. The bulk thermal-assister is configured to produce a temperature in a magnetic-recording disk in a hard-disk drive when the hard-disk drive is disposed in the bulk eraser. The temperature is about equal to a second temperature greater than a first temperature of the magnetic-recording disk. The bulk eraser is configured to erase recorded information from the magnetic-recording disk at the second temperature.

Abstract: Provided is a magnetic recording apparatus including a magnetic recording medium having a magnetic recording position patterned of a magnetic substance and a read head reading information from the magnetic recording medium, wherein the magnetic recording medium includes: a data area having the magnetic recording position patterned including a plurality of data tracks; and a servo area including a servo burst for tracking the data tracks, wherein the servo burst includes a plurality of bursts deviating from one another in a downtrack direction, and a width of each of the bursts is equal to or greater than a width of the read head and narrower than twice the width of the read head. According to this structure, although data is reproduced using a read head having a greater width than a width of each of data tracks, a linear section in which an output voltage is reduced depending on a size of an off-track is formed. As a result, a dead zone can be removed.

Abstract: Embodiments of the present invention recite a method of preserving data on a hard disk drive. In one embodiment, a first copy of data is read from at least one sector of a hard disk drive and stored in a first location. A second copy of the data is stored in a non-volatile memory location of the hard disk drive. The first copy of the data is then modified to create a modified copy. The second copy of the data is then used to verify that the modified copy of data has been correctly written to the at least one sector of the hard disk drive.

Abstract: A corrector circuit for correcting second harmonic distortions is provided. The corrector circuit includes a transconductance circuit having an input transconductance with a transresistance load for receiving a distorted voltage signal having a second harmonic component. The transconductance circuit is adapted to generate a corrected voltage signal having the second harmonic component that is reduced from the distorted voltage signal as a function of the input transconductance. The corrector circuit further includes biasing means for providing a biasing current to the transconductance circuit (with the input transconductance that depends on the biasing current). The biasing means includes means for providing a fixed component of the biasing current, means for providing a variable component of the biasing current (being a function of the distorted voltage signal according to a proportionality coefficient) and means for programming the proportionality coefficient.

Abstract: A method of writing data using a coercivity distribution of a data storage medium, including mapping the coercivity distribution of the data storage medium including a plurality of write spots in which data can be written, measuring a current ambient temperature, and if the ambient temperature is higher than a room temperature, selecting a write spot having a relatively large coercivity to receive write data, and if the ambient temperature is lower than the room temperature, selecting a write spot having a relatively small coercivity to receive the write data.

Abstract: A method for measuring a magnetic interference width for a magnetic recording head is described. The method includes writing a first track at a first frequency on a magnetic disk, writing a second track at the first frequency on the magnetic disk, and writing a third track at a second frequency on the magnetic disk between the first track and the second track. The third track partially overlaps both the first track and the second track and the second frequency is different from the first frequency. The method further includes measuring a readback profile across the first, second and third tracks on the magnetic disk.

Abstract: Embodiments of the present invention help to efficiently determine the appropriate setting of the write current of a magnetic head relative to temperature. According to one embodiment, a test computer determines the set value of a write current as a function of temperature for each head device portion from the relationship between a write current and an error rate. A test execution controller sets a selected head device portion and a write current to an AE, and writes data on a magnetic disk using the components in a HDD. The test execution controller reads the written data, and the error rate of the data from an error correcting section. The test execution controller repeats the same process with the write current varied. Upon completion of the measurement at the preset write currents, the test execution controller transfers the measurement data to the test computer.

Abstract: Timing recovery optimization using disk clock. A novel means is presented to perform and provide control of the sampling frequency of a signal that is read from a disk within a hard disk drive (HDD). Two separate, yet somewhat cooperating control loops are employed to provide feedback control of the sampling frequency of the signal that is read from disk. A timing recovery loop and a disk clock loop operate in conjunction with one another according to some desired manner (which can be predetermined or adaptive) to ensure that the sampling of the signal is performed to a very accurate degree. In one implementation, the timing recovery loop governs the sampling rate until the disk clock loop has locked, from which time either the disk clock loop govern the sampling or some combination of the signals provided from the two loops govern the sampling.

Abstract: A method of performing data/information recording and retrieval utilizing a multilevel patterned magnetic medium, comprises providing a magnetic recording system including a read/write head and a multilevel patterned magnetic recording medium including a plurality of spaced apart data/information storage elements each comprising a stacked plurality n of magnetic recording cells with different magnetic properties and magnetically decoupled from overlying and/or underlying cells; providing relative movement between the write head and magnetic recording medium; and writing to the medium by supplying the write head with a modulated write current comprising a plurality n of pulses of different magnitudes while the head passes over each element, thereby applying n different magnetic field strengths to each element, such that the writing occurs in a single pass of the write head over each element.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of tracks, and a head actuated over the disk. A plurality of refresh zones are defined, wherein each refresh zone corresponds to a plurality of the tracks. Data is written to a first refresh zone, and a first zone counter is updated for a second refresh zone at a first rate. Data is written to a third refresh zone, and the first zone counter is updated for the second refresh zone at a second rate different than the first rate.

Abstract: Systems and methods for detecting and designing enhanced disk sync marks using correlation detection are disclosed. The enhanced sync marks provide better noise immunity and higher detection rates over traditional Viterbi-based detection schemes even with a shorter sync mark length. The disk sync mark may provide optimal noise immunity for a particular target polynomial or a plurality of common target polynomials. The minimum Euclidean distance between a candidate sync mark and a plurality of right-shifted versions of the candidate sync mark is computed and compared with other candidate sync marks. The sync mark with the largest minimum Euclidean distance is then selected as the optimal mark. Systems and methods are also disclosed for detecting and designing a disk sync mark using correlation detection when the polarity of the disk is unknown or time-varying.

Abstract: A data storage device includes a first filter that generates a short DC equalization target in response to a read back signal generated from magnetic patterns that are recorded on a storage medium using perpendicular recording. The data storage device also includes a first detector that generates an output sequence in response to the short DC equalization target. The data storage device also includes a high pass filter that attenuates DC components of the short DC equalization target and that passes low frequency components of the short DC equalization target above a cutoff frequency to generate a filtered signal. The data storage device also includes a second detector that processes the output sequence in response to the filtered signal.

Abstract: Resistivity sense bias circuits are described herein. An example resistivity sense bias circuit for use with a magnetoresistive read head includes a current biasing portion configured to provide a bias current across the magnetoresistive read head thereby establishing a bias voltage across the magnetoresistive read head, a resistivity sensing portion coupled to the current biasing portion and configured to sense a change in the bias current based on a resistivity change of the magnetoresistive read head, and a voltage source to provide the bias voltage and to adjust the bias voltage in response to the resistivity change of the magnetoresistive read head.

Abstract: A data recording component includes a read transducer and a write transducer. A thermoelectric device generates heat flow between the read transducer and the write transducer. The heat flow is conducted by thermal conductors. A controlled current source provides current to the thermoelectric device that changes polarity to change directions of the heat flow and thereby vary a gamma ratio of transducer protrusion.

Abstract: A heat-assisted magnetic head that can efficiently and locally heat a magnetic recording medium. The head includes a heating coil element, and a write head element for writing data signals by generating a signal magnetic field, and a read head element for reading data signals by sensing the signal magnetic field. The heating coil element comprises a main heating magnetic pole layer, an auxiliary heating magnetic pole layer, and a heating coil layer for generating a magnetic flux in the main heating magnetic pole layer and the auxiliary heating magnetic pole layer and passing through at least between the main heating magnetic pole layer and the auxiliary heating magnetic pole layer. The read head element, heating coil element, and the write head element are stacked in this order from an element-formed surface of a substrate.

Abstract: A signal reconstruction technique is used to correct for wow and flutter in analog audio recordings. Elements of the recording are used to generate a signal for correcting the output. Involves locating modulated entities such as bias signal (e.g. frequency-modulated, amplitude-modulated, or phase-modulated entities) in the recording, extracting them, and utilizing them as a carrier to synchronize to a master clock, using the irregularity of the anomaly to indicate the speed and pitch information to be corrected. A carrier frequency is determined and applied to a digitized form of the recording. This may be performed even in the absence of a prescribed reference code or tone, such as a pilot tone laid down purposefully at the moment of recording. In the case of signals presumed to have an error in the carrier, a corresponding signal is buffered, and in the case of a presumed error, a last known signal is used for the duration of the error.

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: A signal conversion circuit includes: an input circuit that rejects common mode inputs and is configured to receive a differential input signal and shift a first bias of the differential input signal to produce a single ended intermediate signal with a second bias; and an amplifier circuit configured to amplify the single ended intermediate signal to produce an amplified signal. The input circuit can include: first and second transistors with drains configured to couple with a supply voltage, and gates of the first transistor and the second transistor are configured to receive the differential input signal; a first resistor coupled to a source of the first transistor and a drain of a third transistor; and a second resistor coupled to a source of the second transistor and a drain of a fourth transistor; where the third transistor and the fourth transistor are connected in a current mirror configuration.

Abstract: Various embodiments of the present invention provide systems and methods for write pre-compensation. For example, various embodiments of the present invention provide methods for modifying magnetic information transfer. The methods include retrieving magnetically represented data from a storage medium, and converting the magnetically represented data to a series of data samples. A preceding pattern and a transition status is identified in the series of data samples, and an equalized channel response is computed based on an estimated NLTS value. An error value is computed that corresponds to a difference between the estimated NLTS value and an actual NLTS value, and a pre-compensation value is computed based at least in part on the error value.