Kabushiki Kaisha Toshiba

Toshiba Electronic Devices & Storage Corporation

Fujitsu Corporation

Takeyori Hara

Takayuki Kawabe

Naoki Tagami

Daisuke Sudo

Takuji Matsuzawa

Makoto Asakura

Kazuto Kashiwagi

Nobuhiro Maeto

Sho Suzuki

Yoshiyuki Kagami

Richard M Ehrlich

Kazuhiko Takaishi

Akihiko Takeo

Siri S Weerasooriya

Shuichi Hashimoto

Tomoyoshi Yamada

Tatsuhiko Kosugi

Isamu Tomita

Tatsuo Nitta

Kei Funabashi

Kazuo Chokki

Masahiro Kanamaru

Ryuki Kubohara

Tatsurou Sasamoto

Nobuyuki Suzuki

Susumu Yoshida

Yusuke Tomoda

Gaku Koizumi

Kazunori Mori

Eiji Okamura

Taturo Sasamoto

Masafumi Sato

Kouhei Takamatsu

Shihpo Hsu

A controller of a magnetic disk device obtains, for each of a plurality of first position sets, a first distribution that is a radial distribution of differences between a target orbit of the magnetic head and an actual position of the magnetic head while correcting a disturbance synchronized with rotation of the magnetic disk by using correction amounts at a plurality of positions included in one of the plurality of first position sets. The controller performs weighting the first distribution according to a position in the radial direction and calculating an evaluation value based on the weighted first distribution for each of the plurality of first position sets. The controller selects a second position set from the plurality of first position sets based on the evaluation value. The controller records correction amounts at a plurality of positions included in the second position set by the magnetic head.

Magnetic disk device and method

According to one embodiment, a magnetic disk device comprises a head position demodulation unit which demodulates a position of the head by performing switching between normal servo demodulation for processing servo information written to a servo sector of the disk and short servo demodulation for processing servo information by a short servo system, and a controller comprises a head position prediction unit which predicts a head position, and the head position prediction unit performs position prediction by using a latest head position obtained by demodulation by the head position demodulation unit and a head position obtained by past demodulation by normal servo demodulation.

Magnetic disk device

According to the embodiment, a controller of a magnetic disk apparatus acquires a first amplitude and a first phase of a first read waveform and a second amplitude and a second phase of a second read waveform by demodulating the first/second read waveforms. The first read waveform is a read waveform of a first burst pattern. The second read waveform is a read waveform of a second burst pattern. The controller acquires weights on the basis of the first amplitude, the second amplitude, the first phase, and the second phase. The controller corrects an initial phase of each of the first read waveform and the second read waveform by calculating a weighted average using the weights, the first phase, and the second phase. The controller executes positioning of the magnetic head on the basis of the corrected first read waveform and second read waveform.

Magnetic disk apparatus and method

According to one embodiment, a controller of a magnetic disk device calculates a first power amount that is an amount of power required for an unload operation of a magnetic head based on a state of a VCM while the VCM is operating. The controller calculates a first set value based on the first power amount. When an amount of second data that is first data stored in a volatile memory and not yet written to a magnetic disk exceeds the first set value, the controller executes a first write operation of writing a part or all of the second data to the magnetic disk. When supply of power from outside is interrupted, the controller executes the unload operation and saving of the second data to a nonvolatile memory by using power generated by a back electromotive force of the second motor.

According to an embodiment, a controller of a magnetic disk apparatus moves a magnetic head to a first track being one of tracks on a magnetic disk. The controller acquires, in a servo sampling cycle, a positioning error amount of the magnetic head with respect to the first track. The controller executes an access to the first track by the magnetic head after a positioning error amount equal to or less than a first threshold is continuously acquired a first set number of times. The controller obtains a frequency estimation value by estimating a frequency of residual vibration of the magnetic head due to movement of the magnetic head to the first track and obtains an amplitude estimation value by estimating an amplitude of the residual vibration. The controller updates the first set number of times on the basis of the frequency estimation value and the amplitude estimation value.

According to one embodiment, a magnetic disk device includes a magnetic disk, a magnetic head, and a controller including an offtrack write table, positioning the magnetic head, and registering an address at which data in a track is written and a positioning error of the magnetic head at the address for the track, in the offtrack write table. When writing data to a first sector, the controller corrects a positioning target position of the first sector, based on a positioning error of a second sector located on two tracks away in a radial direction from the first sector.

Magnetic disk device and method of controlling magnetic disk device

According to one embodiment, a magnetic disk device comprises a feedforward control unit, which includes a plant model processing unit including a plurality of submodel processing units. Each of the submodel processing units generates a submodel output value that is an output value for an input value to be input, and the feedforward control unit generates the output value based on a plurality of the submodel output values.

Magnetic disk device and head control method

According to one embodiment, a magnetic disk device includes a first head which writes and reads to the first disk, a second head which writes data and reads data to the second disk, a first actuator including the first head, a second actuator including the second head, and a controller which performs a first reordering process for a command scored in a first queue corresponding to the first actuator and performs a second reordering process for a command stored in a second queue corresponding to the second actuator, wherein the controller selects a first command to be executed next by the first actuator based on current and future operating states of the second actuator, and executes the first command.

Magnetic disk device and reordering method

According to an embodiment, in a disk device, a first actuator moves a first head with respect to a first surface of a first disk. A controller controls positioning of the first head via the first actuator and controls a write operation to the first disk by the first head. The controller acquires information regarding a state of a vibration source, changes a value of a coefficient for estimating a predicted position of the first head according to the information regarding the state of the vibration source, estimates a predicted position of the first head with the value of the coefficient changed, performs a write operation by the first head in a case where the predicted position estimated is equal to or less than a threshold, and prohibits the write operation by the first head in a case where the predicted position estimated exceeds the threshold.

Disk device

According to one embodiment, a magnetic disk device including a disk, a head that writes data to the disk and reads data from the disk, an actuator that is rotationally driven and controls movement of the head mounted above the disk, a microactuator that is mounted on the actuator and finely swings the head in a radial direction of the disk by a piezoelectric element that extends and contracts when a drive voltage based on a bias voltage is applied to the piezoelectric element, and a controller that switches the bias voltage according to an operation state during an access process.

Magnetic disk device and method for switching bias voltage and drive voltage of microactuator

A magnetic disk device includes a plurality of magnetic heads, a storage unit that stores a table storing, for each of the magnetic heads, a track skew value obtained by adding a head shared value and a head unique value, and a control unit that reads out the track skew value corresponding to one of the magnetic heads to be operated from the table and performs seek control.

Magnetic disk device, control method, and non-transitory computer-readable storage medium

According to one embodiment, a magnetic disk device includes a disk including a zone servo boundary area including a first area of a first servo frequency, a second area of a second servo frequency, and a third area of the first servo frequency, in a servo area, a head, and a controller demodulating first servo data of the first area to derive a position of the head and demodulating first corrected data of the third area to correct the position of the head. The first area, the second area, and the third area are aligned in order in a traveling direction. The first area and the second area are adjacent to each other in a circumferential direction of the disk. The second area and the third area are adjacent to each other in the circumferential direction.

Magnetic disk device that corrects position of head by demodulation

According to one embodiment, a magnetic disk device includes a first disk, the second disk, and a first head which writes and reads to the first disk, a second head which writes and reads to the second disk, and a controller which calculates an estimated position at which the second head is estimated to be disposed on the second disk based on first relative position information related to a relative position in a radial direction between the first head and the second head when the first head is switched to the second head.

Magnetic disk device and head change processing method

According to one embodiment, a magnetic disk device includes a disk, a head that writes data to the disk and reads data from the disk, an actuator that is rotationally driven and controls movement of the head mounted on the disk, and a controller that estimates a fundamental frequency of a position error signal generated in positioning control of the head, the fundamental frequency corresponding to a disturbance having harmonics, determines the fundamental frequency, determines the number of delay samples based on the fundamental frequency, and suppresses a multiplied frequency that is a harmonic of the fundamental frequency according to the number of the delay samples.

Magnetic disk device and method of compensating for harmonic corresponding to harmonic disturbance

According to one embodiment, a magnetic disk device including a disk, a head, and a controller configured to, when writing a first servo sector, a second servo sector, and a third servo sector in the order described according to a second route varying in a radial direction of the disk with respect to a first route, adjust first timing used to write the second servo sector next to the first servo sector, and adjust second timing used to write the third servo sector next to the second servo sector.

Growing community of inventors

Kawasaki Kanagawa, Japan

Takeyori Hara