Samsung Electronics Co., Ltd.

Hae Jung Lee

Sang Won Lee

Keung Youn Cho

Ken Bovatsek

Geng Wang

Chang-Hwan Lee

Jong Yun Yun

Young-Shin Kim

Weonwoo Kim

Kieu Lien Dang

A method of controlling a flying height of a magnetic head of a hard disk drive includes calculating a corrected flying on demand (FOD) voltage to correct a difference between a measured flying height measured by applying a burn-in FOD voltage corresponding to a target flying height and a burn-in flying height in a reference FOD voltage profile corresponding to the burn-in FOD voltage, using the reference FOD voltage profile, in the reference FOD voltage profile that is a profile of a second signal for calculating the flying height of the magnetic head with respect to a first signal for calculating an FOD voltage that allows an end of the magnetic head to thermally expand and protrude when applied to a heater included in the magnetic head, and applying an applied FOD voltage obtained by applying the corrected FOD voltage, to the burn-in FOD voltage, to control the flying height of the magnetic head. Thus, the reliability in the read/write operation can be improved and performance of the hard disk drive can be improved.

Hard disk drive, method of controlling flying height of magnetic head thereof, and recording medium containing computer program thereon

The invention includes a testing method which may be applied to at least one writer in a disk drive during the self-test phase to generate write parameters, focused on the Over Shoot Control (OSC) of the write current parameter to improve the reliability of write operations by that writer. The Minimum OSC is used for write operations in normal temperatures. The Optimum OSC is used for a first lower temperature range, preferably between essentially 15 degrees Centigrade and essentially 5 degrees Centigrade. The Maximum OSC is preferred below essentially 5 degrees Centigrade. The Minimum OSC should preferably guarantee both an Adjacent Track Write (ATW) criteria, as well as guarantee a Write Induced Instability (WII) criteria. The invention includes the write parameter collection, as well as the disk drive containing the generated write parameter collection. The invention also includes the method of using that write parameter collection to control a writer while writing to tracks belonging to the radial zone collection and program systems implementing the invention's methods.

Methods and apparatus determining and/or using overshoot control of write current for optimized head write control in assembled disk drives

Thermal pole tip protrusion is caused by materials in and around head slider expanding during write operations till they protrude, leading to contact with the rotating disk surface, altering the flying height and often wearing down part of the disk surface. While well known that read-write heads expand during writing, the inventors who recognized this situation's significance, particularly as flying height decreases and data rates increase, both required for high areal density disk drives. The inventors realized that they could detect the problem at the spin stand level by testing head gimbal assemblies to reliably, and inexpensively, predict the tendency for thermal pole tip protrusion. This leads to selection of head gimbal assemblies, which do not have the thermal pole tip protrusion tendency. The selected head gimbal assemblies have better reliability, as do actuators and disk drives made with the selected head gimbal assemblies.

Method of estimating a thermal pole tip protrusion for a head gimbal assembly

A hard disk drive that includes a heater to heat an internal cavity of the drive. The disk drive may also have a temperature sensor to sense the temperature of the internal cavity, and a control circuit to control the heater and maintain the disk drive cavity, to be no less than a threshold temperature. The threshold temperature may correspond to a point where the heads of the drive undergo a significant degradation of performance. Maintaining the disk drive cavity temperature at or above the threshold temperature insures that the heads will not degrade due to temperature.

Installation of heater into hard disk drive to improve reliability and performance at low temperature

The invention includes a testing method which may be applied to at least one writer in a disk drive during the self-test phase to generate write parameters, focused on the Over Shoot Control (OSC) of the write current parameter to improve the reliability of write operations by that writer. The Minimum OSC is used for write operations in normal temperatures. The Optimum OSC is used for a first lower temperature range, preferably between essentially 15&#xb0; Centigrade and essentially 5&#xb0; Centigrade. The Maximum OSC is preferred below essentially 5&#xb0; C. The Minimum OSC should preferably guarantee both an Adjacent Track Write (ATW) criteria, as well as guarantee a Write Induced Instability (WII) criteria. The invention includes the write parameter collection, as well as the disk drive containing the generated write parameter collection. The invention also includes the method of using that write parameter collection to control a writer while writing to tracks belonging to the radial zone collection and program systems implementing the invention's methods.

A method for determining and varying the capacity, track per inch and bit per inch values of a hard disk drive. The method includes determining an optimal track per inch value for each head of the drive. The method then determines whether each head does not exceed a threshold BER value. If one or more heads do not exceed the threshold BER value then the BPI (data rates) of the non-performing heads are decreased until an acceptable BER is achieved. The BPI of performing heads may be increased to insure that the capacity of the disk drive still meets a target value. Likewise, if all of the heads are above the threshold value, the BPI of one or more of the performing heads may be decreased to improve the BER of the heads. The reduction in BPI is limited so that the drive always meets the target capacity value. The BPI and TPI values are stored in memory for use during the operation of the drive.

Flexible BPI and TPI selection in disk drives

The present invention is a method and system to optimize a write channel in a hard disk drive. The method comprises providing a disk having a at least one side with a plurality of tracks, and selecting a target track from the plurality of tracks. Data is written at least once on a predetermined plurality of tracks adjacent to either side of the target track and on the target track. Data is also written a predetermined number of times on tracks immediately adjacent to the target track. Data written on the predetermined plurality of tracks adjacent to either side of the target track and on the target track is then read. The process then determines if a number of errors on the tracks is greater than a predetermined criteria, if so, a write current value of the write channel is decreased, otherwise the write current value is increased.

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Santa Clara, CA, United States of America

Hae Jung Lee