Hitachi Global Storage Technologies Netherlands B.v.

International Business Machines Corporation

Hgst Netherlands, B.v.

Shanlin Duan

Jizhong He

Jane Jie Zhang

Zhupei Shi

Wai Cheung Leung

Li Tang

Yu Lo

Kezhao Zhang

John Stephen Hopkins

Thomas Young Chang

Jinshan Li

Xiaoping Bian

Mohammad Taghi Mirzamaani

Yan Liu

Terence Tin-Lok Lam

James Hammond Brannon

Hang Fai Ngo

Bradley Frederick Baumgartner

Mary Frances Doerner

Zhen Jin

Kenneth E Johnson

Norman Chu

Patricia Galindo

Wei-Ming Lee

Connie H Moy

Bruno Jean Marchon

Ullal Vasant Nayak

Yansheng Luo

Bob Clyde Robinson

Owen R Melroy

Jorge Daniel Colonia

Nalin Zhou

An-Chou Andrew Chen

Roger Yu Lo

Huyen D Do

Ka Chi Wong

Reducing slider bounce within a hard disk drive. A force is received at a first material while the first material is in contact with a disk of a hard disk drive; the first material comprising a portion that is flexible in a first direction and is substantially non-flexible in a second direction. The first direction is a direction that is normal to the disk and the second direction is a direction that is parallel to a surface of the disk. The force is substantially absorbed by the portion that is flexible to reduce the force associated with interaction between the first material and the disk, thereby reducing slider bounce within the hard disk drive.

Reducing slider bounce in a hard disk drive

A tool for testing a magnetic disk for use in a magnetic disk drive. The tool detects surface defects or asperities by detecting a change in electrical resistance corresponding to a temperature change in a thermally sensitive layer. The apparatus includes a slider body having a thermally insulating layer formed on an air bearing surface of the slider body and a thermal sensor layer formed on the thermally insulating layer. The thermally insulating layer prevents thermal heat spikes in the thermal sensor layer (such as resulting from contact with an asperity) from dissipating quickly into the slider body itself. The thermal sensor layer is a material that exhibits a change in electrical resistance in response to a change in temperature and is preferably a PTC thermistor material which exhibits a large change in electrical resistance when a transition temperature has been reached.

High sensitivity glide sensor using frictional heating

Approaches for a testing device for selecting a discrete track media (DTM) format for use with a particular head of a hard-disk drive (HDD). The testing device comprises a continuous magnetic-recording disk, rotatably mounted on a spindle, which stores data using a continuous media format. The testing device also comprises a testing module configured to simulate reading data, stored using a discrete track media (DTM) format, from the continuous magnetic-recording medium. Advantageously, testing time and cost is reduced as both discrete track media (DTM) disks and expensive discrete track media (DTM) recording testing hardware are not required to select the optimal a discrete track media (DTM) format for use with a particular head of a hard-disk drive (HDD). In addition, embodiments may be used to optimize features of the tracks of the DTM disk, such as the land to groove ratio.

Simulating discrete track media with continuous media for head evaluation

Magnetic disk drive systems and associated methods are described for testing magnetic disk performance for certification with a plurality of magnetic disk drive systems prior to installation. The test system may position a slider at a first spacing between the magnetic disk in the slider and simulate the recording performance of a disk drive system with the magnetic disk at the first spacing. The disk drive test system may then transfer a control signal to a heating element in the slider to move the slider to a different spacing between the magnetic disk and the slider to simulate the recording performance of another disk drive system. The test system may, thus, use a single slider to certify a magnetic disk with a plurality of disk drive systems.

Testing magnetic disk performance with a single slider simulating sliders of various disk drive systems

One-sided magnetic media for a hard disk drive. Methods are implemented to create a magnetic media with only one surface capable of recording data. The second surface is a non-data recording side of the media and is constructed so that it does not interfere with the recording properties of the recording side or the structural usefulness of the media. Additionally, the second surface can be a low quality surface capable of limited magnetic recording.

One magnetic sided media for low cost and low capacity applications

Track pitch in a hard disk drive is selected to satisfy the requirements of both off-track capacity (OTC) and adjacent track interference (ATI). The invention separately measures the track pitch requirements for OTC and ATI. The track pitch for the drive is set with the larger of the OTC and ATI track pitches. The OTC track pitch is measured with a 747 curve, and the ATI track pitch is measured by the positions of adjacent tracks at which the on-track error rate is not worse than a given value after the targeted number of adjacent track writes in the ATI requirement.

System, method and apparatus for determining track pitch in a hard disk drive to satisfy the requirements of both off-track capacity and adjacent track erasure

Methods and test systems are disclosed for determining the quality of an erase process for perpendicular magnetic recording (PMR) disks. After performing an erase process on a PMR disk and before the PMR disk is assembled into a hard disk drive, a first test pattern of magnetization pulses is written to a region of the PMR disk. A second test pattern is subsequently read from the region of the PMR disk. The second pattern of magnetization pulses is analyzed in relation to the first test pattern and measured to determine the quality of the erase process.

Determination of the quality of an erase process for perpendicular magnetic recording disks

Glide test systems and associated methods are described. A glide test system includes a glide test head that is flown over the surface of a recording disk to detect asperities on the recording disk. The glide test head includes a detection pad on the trailing end of the head. Heating elements are fabricated proximate to the detection pad. The heating elements are independently controllable to control the amount of protrusion of different regions of the detection pad. The heating elements thus provide a way to substantially flatten the detection surface of the detection pad, and compensate for an uneven topography on a detection surface.

Glide test heads using heating elements to form a planar detection surface

A method models and calibrates the fly height of a slider above the disk for disk drives. The calibration scheme uses the Wallace spacing loss equation and laser doppler velocimetry to predict fly height and detect the actual fly height of the slider. The slider is vibrated at selected resonances, such as by capacitive coupling to the disk, and the fly height is gradually reduced. In one version, contact between the slider and disk may be detected using an arm electronics sensor. The amplitude of mean-to-peak, vibration detection is used as an indication of the actual fly height and to calibrate the modeled fly height.

System, method and apparatus for direct head-disk clearance measurement by slider vibration and fly height calibration

An apparatus, system, and method are disclosed for fly height detection. The apparatus includes an actuator configured to induce vibrations in a glide head that is configured to detect physical asperities on a disk surface. The apparatus may also include a second end of the suspension arm coupled with the glide head and a sensor module that is configured to communicate with a control module in response to the glide head coming in contact with at least one physical asperity. The system includes the apparatus, a disk having a surface comprising physical asperities, and a head gimbal assembly configured to calibrate a fly height margin for the disk. The method includes inducing vibrations in a glide head, detecting physical asperities on a disk surface, and communicating with a control module in response to the glide head coming in contact with at least one physical asperity.

Apparatus, system, and method for detection of fly height margin using controlled excitation of air bearing mode

Spinstand test improvement that measures Functional Byte Error Rate (F-BER) of a disk. The F-BER is correlated to the BER of a disk. The F-BER test is faster than a BER test. The F-BER test is incorporated into a spinstand tester or the software associated with a spinstand tester.

Method and system for testing of magnetic disks using F-BER

A method for determining whether a spike in a read back signal from a read head positioned over a perpendicular recording disk having a magnetically soft underlayer (SUL) is caused by a defect in the SUL or by a thermal asperity (TA). A first read back signal with the spike is obtained in the absence of a local magnetic field near the read head. Then, a permanent magnet or electromagnet is used to induce a small local magnetic field by the read head, and a second signal is obtained. If the signals are substantially similar, a thermal asperity is indicated. Otherwise a defect in the 13 magnetically soft underlayer of the disk is indicated.

System and method for determining whether defect in perpendicular recording disk drive is from thermal asperity or defect in magnetically soft underlayer

A magnetic test module runs on a spin stand to detect amplitude decay and noise evolution at the same time. Signal-to-noise ratio (SNR) decay is directly measured. The recording performance is correlated better with SNR instead of signal only. The thermal stability of the system is evaluated more accurately with this SNR decay method. A heater is placed under the media disk, and a remote sensing thermometer and temperature controller form a subsystem to set up desired environmental temperature. The heater creates a heated band and the read/write head flies above the heated band. The temperature control system may be removed when SNR decay measurement is performed under room temperature.

System, method, and apparatus for detecting signal-to-noise ratio decay in perpendicular magnetic recording

A glide head calibration technique uses two fly height calibrations on a disk media certifier. The first calibration point uses a spin down on bump technique at a first height, and the second calibration point uses a spin down on disk media roughness at a second lower height. With two height data points, a fly height curve of each glide head is approximated very accurately. Once the fly height curve is derived for each head, any fly height can be dialed-in by the disk media certifier for glide testing. This technique achieves glide fly heights between about 4 nm and 8 nm and does so with improved tolerances.

System, method, and apparatus for glide head calibration with enhanced PZT channel for very low qualification glide heights

A method is provided for testing a magnetoresistive sensor for polarity reversal. In one embodiment, the method includes: writing a test pattern on a magnetic disk; providing a mechanical or thermal stress to the magnetoresistive sensor for a period of time; and, comparing the polarity of the test pattern before and after the application of stress.

Growing community of inventors

Fremont, CA, United States of America

Shanlin Duan