Western Digital Technologies, Inc.

Hitachi Global Storage Technologies Netherlands B.v.

International Business Machines Corporation

Western Digital (fremont), Inc.

Soo-Choon Kang

Hongchao Tim Zhao

Siri S Weerasooriya

Sanford A Bolasna

Jeffrey Scott Lille

Hemantha Kumar Wickramasinghe

Guoxiao Guo

Oscar Jaime Ruiz

Remmelt Pit

Chie Ching Poon

Edgar D Sheh

Min Chen

Mark McMaster

Duc H Banh

Scott A Ottele

Kazuhiro Saito

Tony Jing Zhang

Rex Niedermeyer

David Scott C Amiss

Michael Nojaba

Liwei Song

Jianfeng Xu

Hain-Ling Liu

A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a spin torque oscillator (STO). A first bias signal is applied to the STO during a first interval preceding a write operation to write data to the disk, wherein the first bias signal causes the STO to protrude toward the disk. After the first interval, a second bias signal is applied to the STO during a second interval spanning at least part of the write operation, wherein an amplitude of the first bias signal is in the range of 1.1 to 1.5 times an amplitude of the second bias signal.

Data storage device pre-biasing a spin torque oscillator prior to a write operation

A disk drive is disclosed comprising a head actuated over a disk surface, the head comprising a temperature sensitive (TS) fly height sensor. The disk drive further comprises a ramp for parking the head, and control circuitry configured to process a fly height signal generated by the TS fly height sensor, wherein the fly height signal represents a fly height of the head over the disk, and detect whether the head is on the ramp in response to the fly height signal.

Disk drive detecting when head is on ramp

A disk drive is disclosed comprising a head actuated over a disk surface, the head comprising a fly height actuator for controlling a fly height of the head, and a ramp for parking the head. A ramp procedure is executed by applying a control signal to the fly height actuator to decrease the fly height and receiving a corresponding fly height signal, and detecting whether the head is on the ramp in response to the fly height signal.

A disk drive is disclosed comprising a head actuated over a disk, and a fly height actuator operable to control a fly height of the head over the disk. A periodic control signal is applied to the fly height actuator, a frequency response of a touchdown metric at a frequency of the periodic control signal is measured, and a touchdown event is detected in response to the frequency response of the touchdown metric.

Disk drive detecting touchdown event by evaluating frequency response of a touchdown metric

A disk drive to reduce head instability during disk drive manufacturing is disclosed. The disk drive comprises: a disk; a dynamic flying height (DFH) read/write head; a flying height actuator to control the spacing between the DFH read/write head and the disk; and a controller. The controller controls operations in the disk drive including applying a sloped increasing power between a first voltage and a second voltage to move the DFH read/write head towards the disk.

Disk drive to reduce head instability

In one embodiment and method of the present invention, an optical interference fly height (FH) test apparatus for measuring FH is disclosed, in accordance with an embodiment of the present invention, to include a slider, a transparent disk, means for directing a light beam directed between the slider and the disk, and means for iteratively measuring an estimated FH using at least two points of measurement on the slider when the slider is moved away from the disk at a pitch angle, wherein the estimated FH is computed as a function of the pitch angle and during each iteration, a previously-estimated FH is used to converge the estimated FH so that the estimated FH is within a predetermined range from the actual FH.

Iteration method to improve the fly height measurement accuracy by optical interference method and theoretical pitch and roll effect

A disk drive is disclosed comprising a disk, a head actuated over the disk, and control circuitry operable to generate a fly height control signal. A fly height of the head is measured, and the measured fly height is combined with a target fly height and a feedforward signal, wherein the feedforward signal is generated according to:a&#xb7;cos(2&#x3c0;nk/N)+b&#xb7;sin(2&#x3c0;nk/N)where aand bare coefficients and 2&#x3c0;nk/N represents a frequency of a repeatable disturbance in the fly height of the head.

Disk drive employing repeatable disturbance compensation for fly height control

A novel method for defining a touch-down power for a head that has a head-based flying height actuator is disclosed and claimed. A linear relationship between power and spacing is derived by fitting to first and second transducer-disk spacings corresponding to first and second electrical powers applied to the head-based flying height actuator. A third spacing between the transducer and the disk is determined when a greater third electrical power is applied to the flying height actuator. An estimated third spacing between the transducer and the disk, corresponding to application of the third electrical power to the flying height actuator, is calculated using the derived linear relationship and the third electrical power. The touch-down power is defined to be substantially equal to the second electrical power if an error between the third spacing and the estimated third spacing is larger than a first threshold.

Method for defining a touch-down power for head having a flying height actuator

A novel method of selecting an electrical power, to be applied to a subject head-based flying height actuator during operation of a disk drive, is disclosed and claimed. A touch-down power for each of a plurality of representative heads is detected. A relationship between back-off power and touchdown power for the plurality of representative heads is estimated. A touch-down power for the subject head is detected. A back-off power for the subject head is calculated using the estimated relationship and the detected touch-down power for the subject head. The electrical power to be applied to the subject head-based flying height actuator is selected to be equal to the detected touch-down power for the subject head minus the calculated back-off power for the subject head.

Method for selecting an electrical power to be applied to a head-based flying height actuator

A hard disk drive slider has an air bearing surface that uses the ambient air in the disk drive as a heat source for thermal-assisted recording. Incoming air between the slider and the disk surface is pressurized to produce heat sufficient to heat the recording media. A very small thermal pad is located at the trailing end of the air bearing surface and wraps around the magnetic recording head. The thermal pad includes small pockets to contain the heated air to provide heat to the recording media. The air can be pressurized to approximately 80 atm, which is sufficient to raise the air temperature to approximately 800 degrees C. at isentropic conditions. The heated air transfers the heat energy to the recording media by conduction to elevate a disk recording layer temperature for thermomagnetic recording.

Apparatus and method of configuring the air bearing surfaces of sliders in disk drives for producing high temperatures in thermally-assisted recordings

A slider head assembly is provided which includes a slider head for reading/writing data on the surface of a rotating disc. The slider head is disposed in spaced relationship with respect to the disc for read/write (R/W) operations. The slider head assembly is comprised of a body portion having an essentially planar surface positioned to co-act with the surface of the disc with a proximal end and a distal end. The proximal end or trailing slider surface of the head assembly has a read/write element thereat. The distal end or leading slider surface of the assembly has an actuation device mounted thereon, having a surface the position of which can be modified by an external signal to change the position of the head with respect to the planar or air bearing surface (ABS) of the head assembly. This will change the characteristics of the boundary layer of air between the rotating disc and the head, causing the head assembly to move closer to or farther from the rotating disc when actuated by the external signal. A preferred embodiment is a patterned heating element which selectively heats the edge of the leading surface of the slider to cause position modification of the device. The invention also contemplates the head assembly in combination with the rotating disc and a method of controlling the height of the head assembly with respect to the rotating disc.

Slider head having thermally controlled distal end and assembly with a rotating disc

A dual depth slider air bearing surface that enables the slider to achieve a ramp fly height profile near the textured landing zone of a disk. The air bearing slider includes a slider body on which a U-shaped leading ABS pad is defined near and along a leading edge (relative to a moving recording medium) and partially along each side of the slider body. A front step pad extends from the leading edge section of the leading ABS pad to the leading edge of the slider body, at a reduced height relative to the height of the ABS pad. An asymmetric rear pad is defined along a longitudinal axis of the slider body and proximate to a trailing edge of the slider body. Extending above the rear pad is a trailing ABS pad, which has an asymmetric profile with respect to the longitudinal axis of the slider. The trailing ABS pad has a curved bowing profile towards the front of the slider body on the leading edge side of the trailing ABS pad.

Slider air bearing surface having improved fly height profile characteristics

A dual etch depth slider air bearing surface includes a front pad disposed along the front and partially along the sides of the slider and a rear pad partially disposed along the rear of the slider, wherein a skewed center rail connects the front pad to the rear pad. Extending above the rear pad is a V-shaped ABS pad and extending above the front pad are two leading edge ABS pads that are separated by a channel towards the longitudinal center of the slider. The design enables the slider to fly much higher over the landing zone of the disk than at the data zone and provides for a steep take off profile followed by a rapid descend over the data zone.

Air bearing design producing steeper ramp profile near the laser texture zone

A slider air bearing design and method providing &ldquo;writing of laser field&rdquo; (WOLF) measurement without substantial fly height affect. A central pad at ion-mill height is formed in the cavity between the side rails and rear pad. The central pad allows correlation of WOLF crown measurement values with crown measurements obtain via optical interferometer. Also, the central pad provides good reflective areas while preventing degradation in fly height performance due to the rear pad geometry constraints required by the WOLF measurement process.

Slider air bearing design and method providing writing of a laser field (WOLF) measurement without substantial fly height affect

A recording head for a disk drive with a load/unload mechanism has an air bearing on one surface. The air bearing comprises a patterned set of three air bearing pads, at least five shallow pockets and one deep pocket. A narrow gap extends from the deep pocket and separates leading ones of the air bearing pads and shallow pockets from each other. The air bearing pads have unique, step-shaped geometry and the rear pad is virtually free of any shallow area. This configuration gives the air bearing superior performance characteristics over prior art designs with load/unload mechanisms.

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San Jose, CA, United States of America

Soo-Choon Kang