Hitachi Global Storage Technologies Netherlands B.v.

Hgst Netherlands, B.v.

Xiaoyu Sui

Xiaodong Che

Wen-Chien David Hsiao

Yansheng Luo

Hardayal Singh Gill

Changqing Shi

Terence Tin-Lok Lam

John Thomas Contreras

Vladimir Nikitin

Edward Hin Pong Lee

Savas Gider

Quan-chiu Harry Lam

Gurinder P Singh

Samuel Wei-san Yuan

Zhen Jin

Zhong-heng Lin

Theofilos George Fkiaras

Wenchien David Hsiao

Yuanpeng Li

Au Hoan Andrew

Yangsheng Luo

James M Dervin

A method, apparatus, and system for implementing enhanced asymmetric degauss control for a write head for hard disk drives. A degauss period is provided at the end of a write. The write head is driven asymmetrically with respect to the positive and negative driving currents during the degauss period. The average value of the write current during the degauss period is non-zero.

Implementing asymmetric degauss control for write head for hard disk drives

A method and apparatus for providing a write head with an improved pole tip to improve overwrite and/or adjacent track interference. A cross pole tip writer is provided with a shape that is designed to reduce the saturation on the pole tip and aid in the concentration of flux to the down track.

Method and apparatus for providing a write head with an improved pole tip to improve overwrite and/or adjacent track interference

A magnetic write head arranged to maximize efficiency of an optical device used to locally heat a magnetic medium during use, also to maximize efficiency of a heater element for thermal fly height control. The magnetic head is constructed with a read head, a write head and a slider body. The write head is located between the read head and the slider body. A heater element can be located between the read head and the write head and an optical device such as an optical waveguide can be located between the write head and the slider body. The write head can be constructed to have a write pole that is closer to the slider body than the return pole is, thereby allowing the write pole to be adjacent to the optical device.

Thermally assisted magnetic head

A magnetic structure for use in a magnetic recording head, the structure having improved resistance to stray field writing. The magnetic structure can be for example a magnetic shield or a return pole of a perpendicular write element. The structure includes a main body portion which may have a generally rectangular configuration, and first and second wing portions extending laterally from the sides of the body at or near the ABS. The wing portions have a depth measured perpendicular to the ABS that is significantly less than the depth of the body portion (preferably less than 25 percent of the body portion). The wing portions may also have notches formed in their ABS edges. The wings conduct flux from the ABS edge of the body portion and create a flux choking effect for magnetic flux flowing into the wings.

Winged pole and shield structure for reducing stray field in a perpendicular write head

An apparatus for reader characterization is described. The apparatus includes a rotator for rotating a media. The media can contain a signal having a value for a function of a read/write head being assessed. The rotator is operable in conjunction with said apparatus. The apparatus also includes a proximator for proximalizing the media to the read/write head. The proximator is operable in conjunction with said apparatus. The apparatus further includes a writer operable in conjunction with said assembly. The writer writes the signal upon the media. The signal emits the value of the function. The signal is detectable by a reader of the read/write head. The apparatus additionally includes an interface operable in the apparatus for providing removable orientation of the read/write head in an assessing position. The assessing position enables a reader of the read/write head to detect the signal upon rotation of the signal through the assessing position.

Magnetic reader recording characterization at slider or bar level

A hard disk drive (HDD) detects and measures external stray magnetic fields with existing HDD components. After detecting a strong external magnetic field, read and write operations of the HDD are suspended, and/or other proper corrective actions are taken to minimize loss of data. To measure the stray magnetic field, the magnetic head reader is used as a field sensor. The resistance of the reader changes in the presence of the field, such as with the preamp in the HDD. The resistance also changes with temperature. If the temperature inside the HDD is measured, the resistance change due to temperature is normalized. Even without being able to measure the HDD temperature, the stray magnetic field can be measured with a top head and a bottom head in the HDD. The temperature sensitivity of the reader is thereby cancelled out.

System, method, and apparatus for in-situ stray magnetic field measurement

A magnetoresistive sensor having adaptive biasing of its free layer through use of an electromagnetic biasing system incorporated into a magnetic head.

Adaptive domain stabilization for magnetic recording read sensors

A method and apparatus for optimizing data record quality on a disk for a pair of read and write heads, in which the write head is bigger, by adaptively varying linear and track density of overlapping recorded tracks to achieve a target storage capacity. In the method, target storage capacity and radial writing direction are selected. Read and write widths of heads are determined. A linear density and offset distance pairing for optimizing record quality at target storage capacity is determined, wherein offset distance is less than write width but greater than read width. The write head writes a track at the linear density, is offset in the radial direction by the offset distance, and the offset distance is stored. The write head writes a new track at the linear density. Offsetting, storing offset, and writing a new track are repeated until desired data is written into a cluster.

Method and apparatus for optimizing record quality with varying track and linear density by allowing overlapping data tracks

A method for measuring a magnetic read width MRW of a magnetic read sensor directly from the derivative of a full track profile, with better accuracy and more advantages than the micro-track method was invented and also there is no need to use a separate wide write head. The magnetic write width MWW of the write head, without the influence of sensor side reading, can also be obtained by this method along with the MRW with no additional calculations.

Full track profile derivative method for read and write width measurements of magnetic recording head

A method and system for adaptively limiting an off-track recovery displacement of a recording head during an off-track data recovery operation. A head disk assembly (HDA) includes an actuator that positions the recording head in accordance with an actuator control signal. First, an off-track recover displacement threshold is determined utilizing an off-track data field which overlays an on-track data field. The recording head is displaced with respect to the track center until the on-track data field is read. The relative displacement required to retrieve the on-track data is utilized as the threshold. In response to a failed read attempt, a data recovery procedure commences whereby the recording head is incrementally displaced from the track center while attempting to recover the data. During the DRP, the predetermined off-track recovery threshold is utilized to limit the head displacement such that the input/output (I/O) data integrity of the off-track recovery is ensured.

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Fremont, CA, United States of America

Xiaoyu Sui