Kabushiki Kaisha Toshiba

Toshiba Electronic Devices & Storage Corporation

Fujitsu Corporation

Toshiba Storage Device Corporation

Takayuki Kawabe

Takeyori Hara

Ichiro Watanabe

Takuji Matsuzawa

Naoki Tagami

Kazuto Kashiwagi

Makoto Asakura

Nobuhiro Maeto

Daisuke Sudo

Sho Suzuki

Toru Ikeda

Akihiko Takeo

Haruhiko Izumi

Yusuke Tomoda

Shigeru Arai

Akira Minami

Toru Yokohata

Hitoshi Komoriya

Tatsuo Nitta

Masateru Sasaki

Tadashi Sato

Masahiro Kanamaru

Masahide Kanegae

Nobuhiko Isato

According to an embodiment, a controller executes a determination operation when a magnetic head passes over a servo sector during a write operation. In the determination operation, a first cumulative amount is calculated by accumulating, for a first section, evaluation amounts each corresponding to an amount by which the width of an adjacent track is narrowed due to the write operation, and determination is made as to whether the first cumulative amount is smaller or larger than a threshold value corresponding to a limit of error correction. When the first cumulative amount is determined to be larger than the threshold value, the controller interrupts the write operation and re-executes the determination operation after executing a rotational delay. The controller resumes the write operation when the first cumulative amount is determined to be smaller than the threshold value as a result of the re-executed determination operation.

Magnetic disk apparatus and method

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 includes a disk, a read head, and a control unit. The control unit includes a read processing unit that executes first read processing of moving the read head to n1 radial positions within a period in which the disk makes m1 rotations and reading the data of the track, a comparison unit that derives a first signal of highest quality, and a determination unit that determines a radial position at which the first signal of the highest quality is derived as a first appropriate read position. Where 1≤m1<n1.

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.

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 comprising a magnetic disk, a magnetic head, and a controller that registers an address and a positioning error, determines whether or not a positioning error of a second sector that is two tracks ahead in a radial direction of a first sector to which a data is written is registered, and when the positioning error of the second sector is registered, sets a first threshold that allows a write operation for a positioning error of the first sector based on the positioning error of the second sector, and determines whether or not the positioning error of the first sector exceeds the first threshold, and stops the write operation when the positioning error of the first sector exceeds the first threshold.

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, 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 includes a disk, a head that has a write head that writes data to the disk and a read head that reads data from the disk, and a controller that changes an offset amount during read processing according to a vibration applied by a disturbance.

Magnetic disk device and read processing method

According to one embodiment, a magnetic disk device includes a disk including a first sector arranged at a first radial position deviated from a target position in a radial direction by a first offset amount larger than a first threshold value, a head that writes data to the disk and reads data from the disk, and a controller that reads the first sector by arranging the head at a second radial position deviated from the target position by a second offset amount different from the first offset amount.

According to one embodiment, a magnetic disk device includes a disk including a first track including a first sector, a second sector, and a first parity sector, a head, and a controller configured to, when writing a second track adjacent to the first track in the first direction, even if, in a third sector of the second track adjacent to the first sector in the first direction, a first upper limit in a second direction opposite to the first direction, continue the processing of writing data to the third sector, and if, in a fourth sector adjacent to the second sector in the first direction, a second upper limit in the second direction, stop the processing of writing data to the fourth sector.

Magnetic disk device and write processing method

According to one embodiment, a magnetic disk device includes a disk including a first servo sector including a first preamble, a first servo mark, a first gray code, and first burst data, a head including a write head which writes data to the disk and a read head which reads data from the disk, and a controller which stops write processing, based on a write mask gate different from a first servo gate executing read processing of the first servo sector and a write gate executing the write processing to the disk.

Magnetic disk device and servo read processing method

According to one embodiment, a magnetic disk device includes a disk including a plurality of servo data items, a head including a write head which writes data to the disk, and a first read head and a second read head which read data from the disk, and a controller configured to position the head based on a first signal in which write data positioned between the servo data items of the disk is read by the first read head, and a second signal in which the write data is read by the second read head separated from the first read head in a radial direction of the disk.

Two-dimensional magnetic recording device capable of positioning the head based on reading of first and second readers

According to one embodiment, a magnetic disk device includes a disk, a head configured to write data to the disk and read data from the disk, and a controller configured to control the head to write a first track based on a first error rate read immediately after writing a second track adjacent in a radial direction of the disk to the first track.

According to one embodiment, a magnetic disk device includes a disk, a head configured to write data to the disk and read data from the disk, and a controller configured to write position information of the head when writing a first track of the disk and a second track partially overlapping with the first track in a first region of the first track at which read processing on the first track is started.

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Sagamihara Kanagawa, Japan

Takayuki Kawabe