International Business Machines Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Western Digital Technologies, Inc.

Lenovo (singapore) Pte. Ltd.

Hgst Netherlands, B.v.

Hitachi Global Storage Technologies

Tetsuo Ueda

Hideki Ohzeki

Yukio Fukushima

Hideo Asano

Isao Yoneda

Hien Phu Dang

Hiroshi Uchida

Yuzo Nakagawa

Kazushige Okutsu

Sri Muthuthamby Sri-Jayantha

Arun Sharma

Kenji Okada

Kiyoshi Satoh

Hiroyuki Ono

Satoshi Ishii

Toshio Kakihara

Kazuyuki Ishibashi

Mirei Hosono

Noboru Yoshida

Atsushi Kanamaru

Koichi Arai

Toshiaki Wada

Masayuki Takeuchi

S M Sri-Jayantha

Kiochi Takeuchi

Nayouki Kagami

Masaaki Noguchi

Masato Taniguchi

Gaku Ikedo

Tetsuya Tamura

Fuminori Sai

Chuanwen Ji

Tatsuya Sakai

Shinsuke Nakagawa

Takashi Kuroda

Alexander Babinski

Katsuhiko Katoh

Kazunari Tsuchimoto

Atsushi Tobari

Jiro Abe

Sachiyo Baba

Hengchang Guo

Naoyuki Minami

Chikako Sasaki

Tatsuya Endoh

Masahito Nitta

Shunsuke Kobayashi

Emi Shimono

Hidetsugu Tanka

Yoshihiro Nakagawa

A data storage device is disclosed comprising a head actuated over the disk. A first notch filter is calibrated at a first temperature, and a second notch filter is computed for a second temperature based on the first notch filter and a first delta temperature between the first temperature and the second temperature. The second notch filter is computed by transforming a continuous-time transfer function of the first notch filter adjusted by the first delta temperature into a discrete-time transfer function of the second notch filter.

Data storage device computing notch filters for multiple temperatures

A servo control system configured to position a head in accordance with position error signals between servo data on a disk read by the head in a servo sampling cycle and a target position. The system includes a plurality of adaptive peak filters connected in parallel configured to filter the position error signals and configured to change filter coefficients adaptively, and an estimator configured to estimate head vibration caused by disturbances using the servo data read by the head. The system further includes a selector configured to select a portion of the plurality of adaptive peak filters at preset occasions, and a setter configured to update coefficient settings of the portion of the adaptive peak filters selected by the selector in accordance with an estimation by the estimator.

Head servo control system and head servo control method

A hard-disk drive. The hard-disk drive includes a magnetic-recording disk having a plurality of tracks formed thereon. The hard-disk drive also includes a magnetic-recording head configured to be positioned over a target track selected from the plurality of tracks and configured to write data to and to read data from the target track. Moreover, the hard-disk drive includes a range-definer configured to define an allowed range of a position error of the magnetic-recording head corresponding to the target track. In addition, the hard-disk drive includes a write-enabler configured to determine whether writing data by the magnetic-recording head is allowed based on the position error of the magnetic-recording head with respect to the target track and the allowed range that is calculated from data read out by the magnetic-recording head.

Hard-disk drive, method of controlling the hard-disk drive, and method of manufacturing the hard-disk drive

A method (and structure) senses a rotational vibration of a disk drive. The disk drive includes a rotating disk. The disk includes a plurality of reference bits across a surface thereof. The method (and structure) includes detecting the reference bits across a pattern on the rotating disk, and analyzing a time interval between adjacent ones of the reference bits.

Method and system for time-shift based rotational vibration sensing in disk drives

Detection capability of a servo timing mark (STM) is improved. Long STM is configured by pseudo-STM forming part of an AGC/PLL pattern and intrinsic STM. When a system can not recognize the intrinsic STM, it keeps a state that a sector detection window is opened, and is operated in a long STM detection mode to recognize the long STM, thereby generates an STM detection signal. After the STM detection signal has been generated, an STM detection window is closed, and the system is operated in an intrinsic STM detection mode. Since the long STM has longer bit length than the intrinsic STM, it has high discriminating power with respect to other bit patterns. Therefore, even if the sector detection window is remained to be in an opened state, bit strings of data sector, address information in a servo sector or the like is not falsely recognized.

Method and apparatus for detecting servo timing marks in a magnetic disk system

Embodiments of the present invention help to achieve a read error recovery, and suppress decreases in the capacity of the disk drive device and degradation in performance. In one embodiment, a hard disk drive (HDD) performs following control without use of repeatable run-out (RRO) compensation information on a magnetic disk in a normal reading process. When an error occurs in a normal reading process, the HDD moves a read element to a position different from a target position of the normal reading process. At the position where the read element has been moved, the read element reads out the RRO compensation information. In a recovery procedure for the reading process where the error has occurred, the HDD performs following control with compensation by the servo compensation information read out by the read element.

Disk drive device and method for error recovery procedure therefor

Embodiments of the present invention provide a disk drive capable of reducing, by means of simple control, vibrations applied to the drive and vibrations occurring in the drive, and a control method for controlling the disk drive. In one embodiment, a servo system comprises a sensor unit for detecting vibrations, a correction signal generator for, when the sensor unit detects vibrations, generating a correction signal, a position error signal generator for generating a PES signal on the basis of servo data read out from a disk and a target position, a servo controller for generating a servo control signal for controlling a position of a head on the basis of the PES signal, and a servo controller for generating a driving signal on the basis of the correction signal and the servo control signal. The correction signal generator includes a plurality of filters, each of which eliminates vibrations in each different frequency band, the correction signal generator selecting one or two or more RV-FF filters when vibrations are detected, and then generating a correction signal so as to reduce a position error indicated by the PES signal.

Disk drive and control method thereof

Embodiments of the present invention provide a magnetic recording apparatus capable of generating RRO compensation information that can expand the disturbance frequency range in which to compensate for RRO. Embodiments of the present invention describe a magnetic recording apparatus that uses a plurality of repetitive control systems to detect repeatable runout during the rotation of a magnetic recording medium for a frequency characteristic of each of the repetitive control systems. The magnetic recording apparatus further generates compensation information to compensate for each of the detected repeatable runout. The magnetic recording apparatus still further writes the compensation information generated for each of the repetitive control systems to a servo signal, thus suppressing and controlling the repeatable runout.

Magnetic recording apparatus

Embodiments of the invention are directed to detecting an abnormality in head flying height. In one embodiment, an AGC controller establishes the gain of the reproduced signal through gain adjustment using the servo AGC of the servo signal. A digital filter performs filtering processing by use of the obtained gain data g and the gain data of previous sectors. A comparative judgment section obtains filtered gain data G from the digital filter and compares the gain data G with a reference value CRITERIA to determine whether the flying height is normal or abnormal. If the gain G is larger than the reference value CRITERIA, then the data write operation is inhibited. The filter parameters of the digital filter are programmable parameters which can be set and changed.

Data storage device and control method therefor involving flying height

Embodiments of the invention perform a stable data write operation at a low operating ambient temperature and promptly perform a write command process within a magnetic recording apparatus that employs a load/unload design. In one embodiment, write heads unloaded on a ramp are completely preheated before magnetic disks reach their rated rotation speed. This preheat operation takes time T. After completion of write head preheating, the write heads are loaded from the ramp. This loading operation takes time T. Since time Tand time Tdo not sequentially elapse, it is possible to prevent a write operation from being rendered unstable by thermal protrusion while expediting a write command process.

Data reliability improvement at low temperature

Embodiments of the invention reduce the noise occurring when the lubricating layer on the magnetic disk is smoothed. In one embodiment, a magnetic disk drive has a read/write mode parameter table for generating an electric current to be supplied to a voice coil motor when the magnetic head performs data read/write operations on the magnetic disk. The magnetic disk drive also has a smoothing mode parameter table for generating another electric current to be supplied to the voice coil motor when neither a data read nor a write operation is performed on the magnetic disk. The CPU refers to either the read/write mode parameter table or the smoothing mode parameter table and controls the electric current to be supplied to the voice coil motor. When a lubricating-layer smoothing event occurs, the CPU refers to the smoothing mode parameter table and after generating the associated electric current to be supplied to the voice coil motor, moves the magnetic head to seek between the outermost and innermost tracks on the surface of the magnetic disk to perform a smoothing process for the lubricating layer.

Magnetic disk drive and method for seek operations with reduced noise

Embodiments of the invention provide control of a disk data storage device to prevent off-track writing. In one embodiment, the SA acquires the CYLIDs and ADC Values generated from the SERVO SIGNALs acquired previously, and generates DACOUT which defines a driving current of the VCM driver. The SA monitors the DACOUT generated and determines whether the DACOUT is within a predefined range. If the DACOUT is outside the predefined range, data writing is inhibited. By monitoring the DACOUT, it is possible for the VCM driver to detect supply of an overcurrent to the VCM driverbeforehand, and off-track writing can thus be prevented.

Data storage device and control method therefor to prevent off-track writing

To improve the probability of error correction, thereby generating correct read data. Data is read from the same sector by a number of times and a majority decision is done in the same address, thereby the most frequently read value is regarded as the true data value in the address. For example, for an address 00, '00' is handled as a true data value.

Data storage apparatus, read data processor, and read data processing method

The hard disk drive comprises: a magnetic diskhaving servo information stored; magnetic headsseeking on the magnetic diskand staying at a predetermined position to read or write data; a voice coil motormoving the magnetic headsto the predetermined position of the magnetic diska position controller supplying a driving current to the voice coil motorbased on the servo information read by the magnetic headsThe position controller includes: a CPUoutputting a speed control value based on the servo information; a DACand a VCM driverconverting the speed control value into the driving current; and a controllerlimiting a driving speed of the voice coil motorin a case that an output timing of the speed control value is shifted.

Head movement controlling based on servo generated speed control values

Growing community of inventors

Sagamihara, Japan

Tetsuo Ueda