Western Digital Technologies, Inc.

Hitachi Global Storage Technologies Netherlands B.v.

International Business Machines Corporation

Seagate Technology Incorporated

Maxtor Corporation

Robert E Eaton

Bernhard E Knigge

Hai Chi Nguy

Jeffrey R Williams

Erhard Theodor Schreck

Albert John Wallash

Peter Michael Baumgart

Jian J Xu

Gang Herbert Lin

Andreas Moser

Hans Juergen Richter

Noureddine Kermiche

Tao Lin

Mark A Nichols

Puneet Bhargava

Robert L Kimball

Richard George Hirko

Amir Ali Companieh

Rob Milby

Zhen Ye

Ron Carroll

A data storage device is disclosed comprising a head actuated over a disk. A test pattern is read from a first part of the disk to generate a first read signal that is sampled to generate a first sequence of signal samples. The test pattern is read from a second part of the disk to generate a second read signal that is sampled to generate a second sequence of signal samples. A third sequence of signal samples is generated by at least one of amplitude-inverting the second sequence of signal samples, time-inverting the second sequence of signal samples, and amplitude-inverting and time-inverting the second sequence of signal samples. A quality metric is generated based on the first sequence of signal samples and the third sequence of signal samples, and a data density of the disk is configured based on the quality metric.

Data storage device calibrating data density based on amplitude-inverted or time-inverted read signal

A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a laser configured to heat the disk while writing data to the disk. At least four different laser powers are applied to the laser and a fly height of the head over the disk is measured at each laser power. A lasing threshold power for the laser is detected based on the measured fly heights.

Data storage device detecting lasing threshold of laser by measuring protrusion effect

A data storage device is disclosed comprising a head actuated over a disk, wherein the head comprises a fly height actuator (FHA). A FHA control signal is applied to the FHA, wherein the FHA control signal comprises a DC component and an AC component. A fly height metric is measured representing a fly height of the head over the disk for different levels of the DC component. A modulation amplitude of the fly height metric is detected, and a minimum in the modulation amplitude of the fly height metric is detected.

Data storage device detecting minimum stable fly height of a head over a disk

A data storage device is disclosed comprising a head and a disk comprising servo information and a reference pattern comprising a plurality of magnetic transitions. The servo information on the disk is processed to actuate the head over the disk, and a read signal is sampled from the head as the head moves across a width of the reference pattern at a substantially constant velocity to generate signal samples. The signal samples are processed to characterize a geometry of the magnetic transitions.

Data storage device characterizing geometry of magnetic transitions

A data storage device is disclosed comprising a disk, a head comprising a touchdown sensor, and a fly height actuator (FHA) configured to actuate the head vertically over the disk based on an FHA setting. The data storage device is configured into a read mode, and while in the read mode, the FHA setting is adjusted until the head contacts the disk and a touchdown read mode resistance of the touchdown sensor is measured. The data storage device is configured into a write mode and the FHA setting is adjusted so the head is not contacting the disk. While in the write mode, a non-touchdown write mode resistance of the touchdown sensor is measured, and a write touchdown FHA setting that will cause the head to contact the disk while in the write mode is estimated based on the touchdown read mode resistance and the non-touchdown write mode resistance.

Data storage device calibrating fly height actuator based on read mode touchdown resistance of touchdown sensor

Real time monitoring inconsistent operations in a hard disk drive, wherein the hard disk drive comprises a magnetic disk, a controller and a channel clock. A timing signal from the channel clock is measured in real time in the controller. Time intervals between sector identifier marks of the magnetic disk are detected using the timing signal from the channel clock during reading and writing operations of the hard disk drive in the controller. An inconsistency in the drive operations is detected in the controller based on changes in the time intervals between the sector identifier marks is detected during operation of the hard disk drive. The detection of the inconsistency in the drive operations is responded to.

Real time monitoring inconsistent operations in a hard disk drive

A method for monitoring a fly height of a magnetic transducer comprises flying the magnetic transducer at a distance of separation from a recording media. The fly height is modulated with a predetermined modulation frequency with a fly height control device. A read-back signal is read from the recording media with the magnetic transducer. A change of the read back signal is measured that results from modulating the fly height. A fault signal is provided in response to the change crossing a threshold.

Monitoring a fly height of a magnetic transducer

An apparatus and method for testing a component of a magnetic disk drive in which one or more drive-based components is used in the testing process. Each of the drive-based components is based on a corresponding one of the components of the magnetic disk drive. During testing, the component to be tested and at least one of the drive-based components are selectively engaged.

Apparatus and method for testing magnetic disk drive components using drive-based parts

A method for monitoring a fly height of a magnetic transducer comprises flying the magnetic transducer at a distance of separation from a recording media. A read-back signal is read with the magnetic transducer from the recording media. The read-back signal is rectified to produce a rectified signal. The rectified signal is filtered thereby providing a filtered signal. A fault signal is provided in response to the filtered signal exceeding a threshold.

A disk drive includes a disk for storing information, a head with a transducer that writes data to and reads data from the disk, and an AC power source. The head is suspended adjacent to the disk and a flying height gap exists at the head/disk interface. The AC power source generates an AC exciter signal across the flying height gap that discharges electrostatic charge at the head/disk interface. The head/disk capacitance can be measured based on the AC exciter signal to sense the flying height. The AC exciter signal can also alter an attraction force between the head and the disk and thus control flying height. The AC exciter signal can also be based on a flying height signal representative of the head/disk capacitance and thus the flying height.

Disk drive with AC exciter for head/disk interface

A method and apparatus is disclosed for recovering data with unstable low amplitude magnetorestrictive heads. After an error in data recovery is detected a technique is invoked that changes the bias current through the magnetoresistive head to the reverse direction in a predetermined manner. The method includes reversing the bias current direction, returning the bias current to its normal state and reading the data from the storage medium. Alternatively, the method includes reversing the bias current direction and reading the data when the bias current direction is reversed.

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San Jose, CA, United States of America

Robert E Eaton