Hitachi Global Storage Technologies Netherlands B.v.

International Business Machines Corporation

Hideki Ohzeki

Tetsuo Ueda

Kazuyuki Ishibashi

Hiroshi Uchida

Isao Yoneda

Kenji Okada

Kazunari Tsuchimoto

Masaharu Kawamura

Hien Phu Dang

Arun Sharma

Hideo Asano

Kiyoshi Satoh

Akira Kibashi

Toyomi Ohsawa

Noriaki Satoh

Mirei Hosono

Koichi Arai

Toshiaki Wada

Takahiro Saitoh

S M Sri-Jayantha

Kiochi Takeuchi

Nayouki Kagami

Noboru Yoshida

Tatsuo Takagi

Yoshikatsu Fujii

Hiromi Nishimiya

Shunichiroh Ohta

Naoyuki Minami

Koichi Takeuchi

A disk drive. The disk drive includes a head, a motion mechanism, and a controller. The head is configured to access a disk configured to store data. The motion mechanism is configured to move the head. The controller is configured to determine a seek direction when an error occurred; and, the controller is configured to repeat a seek as a repeat seek to a target radial position from a direction opposite to the seek direction in an error-recovery process for the error which occurred in the seek in which the head moved to the target radial position.

Disk drive and error-recovery processing method

Embodiments of the present invention provide a magnetic disk drive capable of easily suppressing degradation of position error caused by disturbance resulting from vibration from the outside. According to one embodiment, the magnetic disk drive acquires, during a period of time of track following control, data necessary for determining a filtering characteristic required to newly be specified in a peak filter; in association with the start of subsequent seek control, determines the filtering characteristic required to be specified in the peak filter; and specifies the determined filtering characteristic in the peak filter.

Magnetic disk drive and control method thereof

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 in accordance with the present invention provide a magnetic disk drive with reduced noise during seek operation without causing any delay in control response. According to one embodiment of the present invention, a control circuit of a magnetic disk drive controls the drive power supplied to a voice coil motor during a seek operation adapted to move a magnetic head over a target track formed on a magnetic disk so as to bring the travel speed of the magnetic head close to a predetermined target speed. The control circuit determines a provisional current according to the difference between the predetermined target speed and an actual travel speed in an acceleration zone adapted to accelerate the magnetic head to the predetermined target speed. If the provisional current exceeds a limit specified in relation to an elapsed time from the start of acceleration, the control circuit sets the limit as the current of the drive power supplied to the voice coil motor to control the motor.

Magnetic disk drive with controlled transducer movement during a seek

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 accurate pitch control of a servo write track. A Self-Servo-Write (SSW) according to an embodiment of the present invention determines a reference APC by reading a mark formed on the recording surface corresponding to the propagation head prior to starting the product servo pattern writing. The accurate size of the mark in the radial direction is known previously. The reference APC is for determining the track pitch, and by using the mark with the determined size, the product servo patterns can be written with a desired and accurate track pitch.

Method of writing pattern on magnetic disk and device therefor

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 allow a heater to reduce the clearance between a head element section and the magnetic section while reducing the risk of collision between the head element section and the magnetic disk during load/unload. In one embodiment, an HDD judges whether a heater is ON or OFF after the load process is started. If the heater is found set to ON, the HDD sets the heater to OFF. With the heater kept OFF, the HDD starts the actuator pivoting. If the heater is found set to OFF, the HDD moves the actuator from the parking position to the magnetic disk with the heater kept OFF. Upon completion of the load process, the HDD goes to the subsequent process. Since the heater is OFF during load, the risk of collision between the head element section and the magnetic disk is reduced.

Disk drive with heater for slider and control method thereof

Embodiments of the invention reduce a possibility that a head will collide with a medium when the clearance between the head and the medium is adjusted by using a medium, and sufficiently reduce the clearance even at an initial stage of accessing a data area. In one embodiment, a hard disk drive (HDD) keeps a heater in an OFF state for a period of time from the start of seek operation until the specified timing after a following mode starts. This prevents a head element from colliding with a magnetic disk, and also prevents flying properties from changing due to the deformation of the ABS. In the above specified timing, the heater is switched from OFF to ON. Specifically, for example, on completion of seek operation, in the timing in which a head arrives at a target track, or in the timing in which an HDC/MPU enters the following mode, the heater is turned ON.

Data storage device with heater, and control method therefor with timing control

Embodiments of the invention reduce a possibility that a head will collide with a medium when the clearance between the head and the medium is adjusted by using a medium, and sufficiently reduce the clearance even at an initial stage of accessing a data area. In one embodiment, a hard disk drive (HDD) switches a heater from OFF to ON in the specified timing after a seek mode is switched to a following mode. Specifically, for example, on the completion of seek operation, in the timing in which a head arrives at a target track, or in the timing in which an HDC/MPU enters the following mode, the heater is turned ON, and this state is kept unchanged until access to the target sector is made.

Data storage device with heater, and control method therefor involving different control modes

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 provide a disk drive, a manufacturing method thereof, and a disk-drive controller which are capable of improving yield without increasing costs so significantly. When track-following control is performed, HDC detects the current position of a read/write head, based on the reproduced output of a servo sector from a channel unit, and makes a calculation of servo data by employing both an integral parameter corresponding to a target track to be read onto a RAM and the detected current position of the read/write head.

Method of using an integral parameter for correct placement of a read/write head

A disk drive seek control system device to reduce track pitch. When data is recorded, an offset value is added to the position of a read head element along the width of a track corresponding to an offset &Dgr;w between the read head element and a write head element. The value of the offset depends on the yaw angle &thgr; of the head. When data is read, the position of the read head element is chosen to be either the position of the write head element during write operations, or the midpoint between the position of the write head element and the read head element during write operations, or the center of a track.

Method and apparatus for disk drive seek control

In order to handle platter flutter in a hard disk operated at high speed (e.g. 10,000 RPM) and maintain tracking of read/write head, peak filters are added to a head tracking servo feedback loop. In some embodiments, several lag-lead type peak filters centered at a plurality of flutter mode frequencies are provided to process a Position Error Signal (PES) read from the read/write head. The several filter are preferably arranged in series (i.e. to operate on the PES sequentially), alternatively the filters can be arranged in parallel. Phase lags and leads caused by the several filters partially cancel at frequencies intermediate center frequencies of the several filters. According to another embodiment two or more, preferably three narrow band filters are used to cover the spectrum of each flutter mode. In a configuration mode, a spectrum of the flutter modes can be obtained and used to set the center frequencies, and bandwidths of filters used to filter out the flutter modes.

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Kanagawa, Japan

Hideki Ohzeki