Kabushiki Kaisha Toshiba

Toshiba Electronic Devices & Storage Corporation

Masafumi Iwashiro

Masahide Yatsu

Hideo Sado

Kazuhiko Takaishi

Seiji Mizukoshi

Takao Abe

Hiroshi Kubota

Atsushi Suzuki

Shouji Nakajima

Shinichirou Kouhara

Shinichiro Kouhara

Shoya Yamamoto

According to an embodiment, a controller corrects an instruction value of a VCM current by a first feedforward control based on a first detection value obtained by a first sensor. The controller executes a first operation in accordance with occurrence of a set event. In the first operation, the controller acquires a first waveform that is a waveform of a deviation amount of a detection position from a target position of a magnetic head, and acquires from the first waveform a first frequency band that is a frequency band whose amplitude is greater than a first threshold. The controller adjusts a coefficient of a transfer function of the first feedforward control to suppress the first detection value in a second frequency band different from the first frequency band and output a correction amount for a first instruction value based on the first detection value in the first frequency band.

Magnetic disk device and method

According to one embodiment, first, a frequency to be corrected by an MA additional filter is specified based on a head position error spectrum and a multi-rate sensitivity characteristic, in a state before the MA additional filter is added. Then, a candidate in which a peak of the multi-rate sensitivity characteristic is equal to or less than a threshold value and a head position error is minimized is determined as the MA additional filter to be used, in a state in which each of a plurality of candidates of the MA additional filter is added.

Method for manufacturing disk device and computer program product

A disk device includes a first controller configured to determine a first operation amount of a first actuator based on a difference between a current position and a target position of a head, a second controller configured to determine a second operation amount of a second actuator based on the difference, and a processor. The processor is configured to perform a first filtering to calculate a first filter value based on a vibration detected at multiple points in time and filter coefficients, perform a second filtering to generate a second filter value based on the vibration detected at each of the multiple points in time, and update the filter coefficients based on the second filter values and a difference between the target position and an updated position of the head.

Disk device

According to one embodiment, a magnetic disk device reads servo information from a recording surface of a magnetic disk using a head, detects a position of the head based on the servo information, and estimates a vibration frequency of a disturbance applied to the head and filtering the estimated vibration frequency from a drive signal of the head. In the filtering, a position error is calculated using a target position of the head given when driving the head and the detected position of the head, a plurality of the vibration frequencies is estimated by executing the vibration frequency estimation based on the position error in a plurality of stages in series, and estimation results of the vibration frequencies are filtered in parallel from the drive signal of the head.

Magnetic disk device and head position control method

A magnetic disk device includes a magnetic disk, a magnetic head, a voice coil motor which drives movement of the magnetic head relative to the magnetic disk, a drive circuit which drives the voice coil motor, a memory in which a seek time for a seek operation is stored in association with a seek distance of the magnetic head, and a controller. The controller changes the seek time stored in the memory in association with the seek distance based on a temperature and a power supply voltage of the drive circuit.

Magnetic disk device and command reordering method thereof

A magnetic disc device according to an embodiment has a head, a position detector, and a filter unit. The position detector detects position information of the head on the basis of servo information. The filter unit performs filtering of an estimated frequency estimated by a quadratic adaptive digital filter that performs self-adaptation for a transfer function on the basis of positional difference information between position information and target position information of the head and adjusts all filter coefficients included in the transfer function on the basis of the estimated frequency.

Magnetic disc device and position control method

According to one embodiment, a magnetic disk device includes: magnetic heads; a magnetic disk in which servo patterns having different write frequencies from one another are divided and recorded into a plurality of zones; and a head controller configured such that, when performing seek control of the magnetic heads based on a model position and a model velocity obtained from a model which simulates the magnetic heads, the head controller corrects the model position and the model velocity, at the time of switching of the zones, so as to reflect variation of sampling time resulting from gaps between the zones.

Magnetic disk device and method of controlling magnetic heads

A magnetic disk device includes a magnetic disk on which servo information is recorded, a head to read the servo information of the magnetic disk, and a position control module. When carrying out positioning control of the head, the position control module estimates frequency components of noise in a head positioning control process, using a high-order digital filter that includes first and second variable coefficients that are each based on position error information generated from the servo information read by the head.

Magnetic disk device and head-position control method

According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, a position error signal output module, a vibration pattern detector, an adder, and a head positioning controller. The magnetic head moves over the magnetic disk. The position error signal output module outputs a position error signal based on a difference between a head position of the magnetic head over the magnetic disk and a target position on the magnetic disk. The vibration pattern detector detects a vibration pattern of the magnetic head caused by vibration. The adder adds the position error signal to an offset signal indicating amplitude of the vibration pattern. The head positioning controller moves the head position to the target position based on a result of addition by the adder.

According to one embodiment, in a disk drive using a disk medium storing spiral servo information, a CPU generates virtual servo information having assumed virtual track centers corresponding to centers of concentric data tracks. The CPU performs control to position a head to the center of the concentric data track by using the virtual servo information.

Method and apparatus for servo control using spiral servo information in a disk drive

A method of writing servo information for use in head positioning control on a disk medium incorporated in a disk drive, including executing the head positioning control based on original servo information recorded on the disk medium, producing positioning correction information to correct a positioning error, and recording the positioning correction information in a correction information recording buffer.

Method and apparatus for servo information writing in a disk drive

When a sub-track having burst data A and D, a sub-track having burst data A and C, a sub-track having burst data B and C, and sub-track having burst data B and D are repeatedly arranged in this order, in accordance with equations 1 and 2, a sub-track t included in a track T determines the value of a constant n within a range of 1.2 (inclusive) to 1.8 (inclusive) so as to obtain linearity between a position in a disc radial direction r and a head position P in a disc radial direction r in the sub-track t. Subsequently, the head position P is calculated using the determined constant n and equations 1 and 2:=()*||(&#x2212;1)/(|)&#x2003;&#x2003;(1)=()*||(&#x2212;1)/(|)&#x2003;&#x2003;(2)

Head position calculation method in magnetic disc apparatus

A head positioning control system which is applied to a disk drive is disclosed. The system includes a feedback control system which performs head positioning control of a head and a feedforward control system. The feedforward control system detects the amplitude and phase of a disturbance based on the position error between the position of the head and a target position. The feedforward control system computes a disturbance compensation value for eliminating the disturbance to output the disturbance compensation value to the feedback control system based on each detection result of the amplitude and the phase.

Method and apparatus for head positioning control with disturbance compensation in a disk drive

A disk drive includes a head positioning system having a feed forward control system to correct a RRO component. The feed forward control system has a measuring unit which feeds back the last correction value obtained from the input value of the controller and measures a RRO component generated after the correction and an FF filter which computes a correction value to correct the RRO component.

Method and apparatus for positioning a head in a disk drive with servo writing function

A servo system is disclosed which is applied to a disk drive for detecting characteristic frequency components of a position error between a position of the head and the target position, and calculating a control correction value for correcting a control value. The servo system estimates the frequency components of target value variation from the characteristic frequency components of the position error, thereby modifying the characteristic frequency components to follow the target value variation. Thus, the servo system calculates the control correction value for suppressing the target value variation, and executes head positioning control, using a value obtained by adding the control value to the control correction value.

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Ome, Japan

Masafumi Iwashiro