Samsung Electronics Co., Ltd.

Seagate Technology International

Jae-hyeong Kim

Cheol-hoon Park

Hyung-Joon Cho

Sang-Hoon Chu

Nam-hoon Lee

Yong-Gwon Lee

A servo control method in a seek retry condition includes determining whether the seek retry condition is generated, and terminating a servo control process that is currently performed and decelerating a voice coil motor such that a speed of the voice coil motor is minimized using a back electromotive force when the seek retry condition is generated.

Servo control method and apparatus in seek retry condition and disk drive apparatus using the same

In a method of measuring track widths in a hard disk drive a plurality of estimation values are calculated based on differences in intensity between a plurality first measurement signals produced in relation to a head of the hard disk drive based on a plurality of burst signals stored in servo sectors of a track when the head moves along the track on a first side of a center of the track, and a plurality of second measurement signals produced in relation to the head of the hard disk drive based on the plurality of burst signals when the head moves along the track on a second side of the center of the track opposite the first side. The estimation values are then normalized, and excessive variation in the track widths is detected based on the normalized estimation values.

Method for measuring track width of hard disk drive

A method of and an apparatus for detecting an actuator vibration, and a hard disc drive write control method of avoiding an effect due to the actuator vibration. The method of detecting an actuator vibration includes: obtaining a specified number of position error signal (PES) samples while following a track; performing a time-frequency conversion on the specified number of PES samples; and detecting a magnitude of a conversion coefficient indicating a magnitude of an actuator vibration, in a specified frequency band.

Method of and apparatus for detecting actuator vibration in hard disc drive, and hard disc drive write control method of avoiding effect due to read/write head vibration

A method and system of switching heads in a hard disk drive written using an off-line STW method. In the method, first, deviations between a reference head and each of the heads are calculated. Next, a mapping table having the deviations between the reference head and each of the heads is generated and stored in a memory. Thereafter, when a head switching operation is requested, a current head is switched to a new head to access a track whose number is the same as the track assessed by the current head. A deviation of a track on which the head is positioned, recorded in the mapping table, is applied to the virtual track address of the track on which the head is positioned, thereby obtaining the physical track address of the track on which the head is positioned. The requested track is then accessed based on the obtained physical track address. As described above, in the head switching method, even when disks for a hard disk drive are written using an off-line STW method, the individual disks can be accessed based on an identical virtual track address. Thus, the performance of the hard disk drive is not degraded.

Head switching method and system using track number matching

For compensating for jitter within a data storage device in real time, a jitter amount is determined from timings of servo signals for sectors of the data storage device. A timing of a servo gate pulse is adjusted for accessing another sector depending on the jitter amount. Such a jitter amount depends on the eccentricity of a disc having the sectors within the data storage device.

Compensation for jitter in servo signal within data storage device

A method and apparatus for preventing off tracking from occurring in a hard disc drive that has at least one track formed using servo signals. The method includes preventing off tracking from occurring when a hard disc drive drives a hard disc having at least one track formed by servo sectors on which servo signals are recorded, checking whether the width of the track is uneven using burst regions A, B, C, and D, the burst regions A through D being included on each servo signal, and preventing the occurrence of off tracking when the width of the track is not even. Accordingly, it is possible to prevent a potential occurrence of off tracking due to a track of an uneven width, thereby guaranteeing the reliability of a hard disc. Also, a track of uneven width with other tracks in the hard disc can be changed into a track of even width, thereby increasing the processing yield during manufacturing of the hard disc.

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Yongin-si, South Korea

Jae-hyeong Kim