Kabushiki Kaisha Toshiba

Toshiba Electronic Devices & Storage Corporation

Hideki Hironaka

Takuya Ogawa

Tatsuhiko Kosugi

Daisuke Sudo

Tatsurou Sasamoto

Kenji Itou

According to an embodiment, a magnetic disk device includes a magnetic disk, a magnetic head that accesses the magnetic disk, a motor that moves the magnetic head, a ramp, a motor driver, and a processor. When a voltage value of a power supply voltage falls below a first threshold, the motor driver starts a retract operation of retracting the magnetic head to the ramp by controlling a voltage applied to the motor. When the voltage value of the power supply voltage falls below a second threshold larger than the first threshold, the processor transmits an instruction related to applying a brake to the movement of the magnetic head to the motor driver.

Magnetic disk device

According to an embodiment, a magnetic disk, a magnetic head, an actuator and a processing unit are provided. The processing unit acquires a feature amount from a position error between a demodulated position and an estimated position of the magnetic head based on a frequency resonance characteristic of the actuator or a frequency characteristic of vibration caused by disturbance of the actuator and, based on the feature amount, sets an on-track determination number used for confirming an on-track state of the magnetic head after seeking.

Magnetic disk device and method of setting on-track determination number of magnetic disk device

According to one embodiment, a position demodulation apparatus is provided which demodulates a first demodulated signal and a second demodulated signal, based on a servo-pattern read signal read out by a head from a medium, acquires a plurality of sets of a vector length and phase angle of vectors on a phase plane denoting the first and second demodulated signals, detects a phase angle for which the vector length is greatest based on the sets acquired, and executes rotational correction using the difference between the detected phase angle and a particular reference angle as a correction amount.

Position demodulation apparatus and position demodulation method

A magnetic disk device according to one embodiment includes: a disturbance vibration detector; a movement position controller; and a disturbance compensation module. The disturbance vibration detector detects a disturbance vibration component with respect to a fine-movement actuator. The movement position controller drives each of the fine-movement actuator and a coarse-movement actuator to control a movement position of a magnetic head. The disturbance compensation module corrects the movement position so as to suppress the disturbance vibration component detected by the disturbance vibration detector.

Magnetic disk device and disturbance compensation method for dual-stage actuator

According to one embodiment, a magnetic disk drive includes a detector and a servo controller. The detector detects, as actual timestamps, time intervals at which a head reads servo sync marks recorded on a disk at predetermined intervals. The servo controller controls a VCM actuator and a microactuator with feedback control in order to position the head at a target position. The servo controller comprises a feedforward controller configured to compensate for disturbance. The feedforward controller comprises a difference detector and an integrator. The difference detector detects a deviation of the actual timestamps from target timestamps as a timestamp difference. The integrator configured to convert the detected timestamp difference into displacement of the microactuator by integrating the detected timestamp difference. The feedforward controller provides a manipulating variable corresponding to the converted displacement, to a feedback control loop for the microactuator as a feedforward manipulating variable.

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Machida Tokyo, Japan

Hideki Hironaka