Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Yoshikatsu Fujii

Tsuyoshi Arai

Takao Horiguchi

Masahito Kobayashi

Takashi Yamaguchi

Katsuhiro Tsuneta

Shinji Matsushita

Hidehiko Numasato

Yosuke Hamada

Katsumoto Onoyama

Toshiyuki Kikuta

Tatsuya Ito

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 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 The speed of the magnetic head (slider) withdrawn to the ramp is controlled at the unload operation.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.

Disturbance detection circuit, memory device thereof, and disturbance detection method

A sector servo type magnetic disk apparatus is provided with, in addition to servo signals, a sensor such as an accelerometer for detecting a state of a magnetic head or a support for the magnetic head at a period shorter than a sampling period of the servo signals. Since an accelerometer mounted on the magnetic head or the support for the magnetic head detects an acceleration, the control performance of a servo control system can be improved, such as reduction of generation of mechanism resonance vibrations of a carriage and improvement on detection precision of a speed signal.

Magnetic disk apparatus having an accelerometer for detecting acceleration in the positioning direction of the magnetic head

An apparatus for positioning a magnetic head includes a servo signal detection circuit for detecting a servo signal recorded on a magnetic disk in a predetermined first period, an acceleration measuring portion which is fitted to a part of a mechanism for mounting a magnetic head, outputs an acceleration signal in a direction of positioning the magnetic head, and samples the acceleration signal in a second period shorter than the first period, a comparison processing portion for comparing a deviation value computed from at least either one of the acceleration signal and the servo signal with a predetermined value, a write inhibit signal generating portion for generating a signal inhibiting write of data on a magnetic disk in accordance with the result of comparison in the comparison processing portion, and a manipulated variable compensation portion for generating manipulated variable for adjusting the position of the magnetic head from at least either one of the servo signal and the acceleration signal and a target value of the position of the magnetic head, whereby to prevent erroneous write operation of data onto a magnetic disk due to unsteady positioning error of the magnetic head.

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Atsugi, Japan

Yoshikatsu Fujii