Hitachi Global Storage Technologies Japan, Ltd.

Hitachi, Ltd.

Takao Horiguchi

Shinji Matsushita

Yoshikatsu Fujii

Tsuyoshi Arai

Toshiyuki Kikuta

Tatsuya Ito

Kazuhisa Shishida

Kiyotada Itou

Takahiro Inoue

Takao Araki

Hidefumi Tominaga

When an idle seek operation of a magnetic disk drive is executed under a velocity control utilizing a back electromotive force of a VCM actuator, the accuracy of the velocity control is deteriorated due to temperature variation of the VCM. To eliminate this disadvantage, a calibration of the velocity control is executed by using control information, such as a track number read from the magnetic disk medium. After the velocity control has been executed for an appointed period, by detecting the back electromotive force from the VCM actuator, an MR sense current and a power of a read write LSI are turned on for a time, positioning information on the magnetic disk medium is read out, parameters to be used for the velocity control are calibrated, and thus a stability of the control can be obtained. Hereby, because the positioning information on the magnetic disk medium is not used constantly, the power consumption during the idle seek operation is reduced, and a stable control of the movement can be obtained as well. For a portable system such as a notebook type personal computer in which a magnetic disk drive is employed, the operation is improved with respect to the use of a battery.

Idle seek calibration method for magnetic disk drive and magnetic disk drive with an intermission calibration

In a disk drive, since high-frequency repeatable runout (RRO) components own low correlative relationships between adjoining tracks, a servo control system of a magnetic head is followed to the high-frequency RRO components, and thus, in the worst case, there is a possibility that data which have been previously recorded on these tracks are destroyed. To avoid this problem, both a tracking type repetitive control unit which is followed to low-frequency RRO components, and a rejection type repetitive control unit which cancels the high-frequency RRO components are provided in a following control loop in order that the following control system is not unnecessarily followed to the high-frequency RRO.

Disk drive

In a disk drive system, a data transducer control during a seek operation is based on the distance to be traversed. Acceleration of a motor coupled to the head initiates movement of the head. Deceleration of the motor is initiated based on the distance traversed by the head.

Disk drive system for controlling seek operations

To control load/unload operation of a slider with magnetic head mounted thereon, by which the speed can always be controlled stably while avoiding the slowdown or temporary stop of an actuator during load/unload operation, a magnetic disk drive is configured using magnetic disk media with the servo information written therein beforehand up to the track located at a position corresponding to the landing zone for the load operation of the magnetic head (slider). The speed of the magnetic head (slider) withdrawn to the ramp is controlled at the unload operation. In the stage of initialization for controlling the speed of the load/unload operation, various parameters are recorded and updated to apply a voltage to power amplifier for compensating for the external forces caused by the friction mainly exerted between ramp and slider support members, with reference to the take-off track or the landing track specified in the landing zone.

Load/unload method and a magnetic disk drive using the method

In a magnetic disk device and other memory devices, the scale and cycle of disturbance applied to each memory device are monitored to make a distinction between a harmful shock and harmless vibrations and detect the disturbance. Values at at least two points, of a waveform signal corresponding to the disturbance are captured. A) The above distinction is carried out from the size or magnitude of the inclination of a straight line defined by the two points. B) The function of capturing and storing the waveform signal corresponding to the disturbance as digital data, and outputting a slice level value for providing suitable detection sensitivity from a conversion table based on the digital data, or correcting and adjusting it and outputting the result is further set.

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Odawara, Japan

Takao Horiguchi