Western Digital Technologies, Inc.

Galvin Chia

Huanxiang Ruan

Phillip Scott Haralson

Noureddine Kermiche

Prakash Balasubramaniam

Dennis W Hogg

Ming Jin

Kent Douglas Anderson

Teik Ee Yeo

Shafa Dahandeh

Pradeep K Thayamballi

Davide Giovenzana

Poornima Nookala

Abhimanyu Sharma

Alvin W Tan

Shih Min Liu

Navin E Prabhu

A data storage device is disclosed comprising a first head actuated over a first disk surface, wherein the first head comprises a laser configured to heat the first disk surface while writing data to the first disk surface. A write power is applied to the laser and a first write operation is executed to write first data to the first disk surface during a first revolution of the first disk surface. A first transient decrease in an output power of the laser is detected during the first write operation, and when the first transient decrease in the output power of the laser is detected during the first write operation, a write-verify of the first data is executed during a second revolution of the first disk surface.

Data storage device modifying write operation when a laser mode hop is detected

A data storage device is disclosed comprising a first head actuated over a first disk surface, wherein the first head comprises a laser configured to heat the first disk surface while writing data to the first disk surface. A write power is applied to the laser when executing a first write operation, and the first write operation is paused when a transient increase in the output power of the laser is detected. In another embodiment, a write-verify of the written data is executed when a transient decrease in the output power of the laser is detected.

A disk drive is disclosed comprising a head actuated over a disk, the head comprising a fly height actuator (FHA). A fly height of the head is measured, and a closed-loop fly height control signal is generated based on the measured fly height and a target fly height. The target fly height is adjusted based on a delta generated based on a change in an environmental condition, and an FHA control signal is applied to the FHA based on the closed-loop fly height control signal.

Disk drive adjusting closed-loop fly height target based on change in open-loop fly height control signal

A data storage device is disclosed comprising a disk comprising a plurality of tracks, where each track comprises a plurality of servo sectors and at least one data segment between consecutive servo sectors. The data storage device further comprises a head actuated over the disk, the head comprising a laser configured to heat the disk during write operations based on a laser power. During a first revolution of the disk, the laser power is first increased over a first interval to cause at least part of the head to protrude toward a first data segment of the disk. After the first interval, the laser power is decreased and a fly height pattern is read from the first data segment to first measure a fly height of the head.

Data storage device measuring laser protrusion fly height profile

A data storage device is disclosed comprising a disk, a head comprising a laser, and a fly height actuator (FHA) configured to actuate the head vertically over the disk based on an FHA setting. A first fly height of the head is measured at a first laser power setting, and a second fly height of the head is measured at a second laser power. A FHA write setting is generated based on a calibrated write laser power, the first and second fly height measurements, and a first function representing a nominal FHA delta setting between a read touchdown FHA setting and a write touchdown FHA setting relative to a delta in a fly height of the head due to a corresponding change in laser power applied to the laser, where the FHA write setting is applied to the FHA during the write operation.

Data storage device calibrating fly height actuator based on laser power for heat assisted magnetic recording

A disk drive is disclosed comprising a disk and a head comprising a laser configured to heat the disk while writing to the disk. Data is written to the disk using an operating laser power applied to the laser, and then the data is read from the disk to generate a read signal. A ramp interval is measured for an amplitude of the first read signal to ramp up to a first threshold.

Disk drive evaluating laser performance for heat assisted magnetic recording

A disk drive is disclosed comprising a head actuated over a disk, and a dynamic fly height (DFH) actuator for controlling a fly height of the head over the disk in response to a DFH setting. A touchdown (TD) threshold is initialized, and the DFH setting that causes a TD signal to exceed the TD threshold is determined. The TD threshold is adjusted, and the DFH setting that causes the TD signal to exceed the adjusted TD threshold is determined. A slope of the DFH setting relative to the TD threshold is determined, and an operating TD threshold is determined in response to a change in the slope.

Disk drive determining touchdown threshold

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. A temperature is measured, and a first input power is generated based on a first function of the measured temperature, wherein the first function compensates for a temperature dependent output power of the laser. A second input power is generated based on a second function of the measured temperature, wherein the second function compensates for a temperature dependent coercivity of the disk. The first input power is combined with the second input power to generate a write power applied to the laser while writing data to the disk.

Data storage device adjusting laser input power to compensate for temperature variations

A data storage device is disclosed comprising a disk, a head comprising a laser configured to heat the disk while writing data to the disk, and a fly height actuator (FHA) configured to actuate the head vertically over the disk based on an FHA setting. A write laser power applied to the laser during a write operation is calibrated, a first fly height of the head is measured at a first laser power setting, and a second fly height of the head is measured at a second laser power setting different from the first laser power setting. A FHA write setting is generated based on the calibrated write laser power and the first and second fly height measurements, where the FHA write setting is applied to the FHA during the write operation.

A disk drive is disclosed comprising a disk, a head comprising a laser operable to heat the disk while writing data to the disk, and a fly height actuator (FHA) operable to actuate the head vertically over the disk. A laser power applied to the laser during a write operation is calibrated, and a FHA write setting is generated for the FHA as a function of the calibrated laser power.

Disk drive calibrating fly height actuator and laser power for heat assisted magnetic recording

A disk drive is disclosed comprising a disk and a head actuated over the disk, the head comprising a fly height actuator (FHA). The disk drive further comprises control circuitry including disk access circuitry, wherein during a calibration operation, the disk access circuitry is configured into a calibration mode that increases a heating of the head, and a fly height of the head is measured periodically to generate periodic fly height measurements that vary due to the heating of the head. A dynamic fly height (DFH) write profile is generated based on the periodic fly height measurements. During a write operation, the disk access circuitry is configured into a write mode and a DFH control signal is generated and applied to the FHA based on the DFH write profile.

Disk drive calibrating dynamic fly height write profile for fly height actuator

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks including a first fly height calibration track and a second fly height calibration track. The disk drive further comprises a fly height actuator operable to control a fly height of the head in response to a fly height control signal. When a refresh event is detected, calibration data is written to the second fly height calibration track. After writing calibration data to the second fly height calibration track, the first fly height calibration track is read in order to calibrate the fly height control signal applied to the fly height actuator. After calibrating the fly height control signal, the second fly height calibration track is read in order to recalibrate the fly height control signal applied to the fly height actuator.

Disk drive employing fly height calibration tracks to account for magnetic entropy and thermal decay

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of normal servo tracks each comprising a plurality of normal servo sectors storing head position information, and a fly height calibration servo track comprising fly height calibration servo sectors, each fly height calibration servo sector comprising head position information and a spacing pattern. After positioning the head over the fly height calibration servo track, the head is servoed over the fly height calibration servo track in response to the fly height calibration servo sectors. A dynamic fly height (DFH) setting is calibrated for the DFH actuator in response to the spacing pattern in the fly height calibration servo sectors. After calibrating the DFH setting, the control circuitry seeks the head to a data track defined by at least one of the normal servo tracks, and startup data is read from the data track.

Disk drive calibrating fly height during startup by reading spacing pattern in servo sectors

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 in response to a fly height control signal. A touchdown operation is executed to set an operating fly height control signal by adjusting the fly height control signal until the head contacts the disk. A fly height calibration track is then read to set a fly height reference. When calibrating the operating fly height control signal, the fly height calibration track is read and the operating fly height control signal is adjusted in response to the fly height reference. When the adjusted operating fly height control signal is invalid, the touchdown operation is re-executed to reset the operating fly height control signal and then the fly height calibration track is read to reset the fly height reference.

Disk drive resetting fly height reference generated from a degrading calibration track

A disk drive is disclosed which generates a pole tip protrusion (PTP) measurement by performing a write operation to heat the transducer while measuring a fly height of the transducer. A first data sequence written to the disk is read without heating the transducer to generate a first signal measurement. A second data sequence is then written to the disk in order to heat the transducer, and the first data sequence is again read to generate a second signal measurement. The PTP measurement is then generated in response to the first and second signal measurements.

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Rancho Santa Margarita, CA, United States of America

Galvin Chia