International Business Machines Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Hitachi Global Storage Technologies

Nobuyuki Kitazaki

Isao Yoneda

Kenji Ogasawara

Sri Muthuthamby Sri-Jayantha

Masahiro Shimizu

Arun Sharma

Kiyoshi Satoh

Devendra S Chhabra

Nobuya Matsubara

Yuji Yokoe

Shinji Ueno

Masaomi Ikeda

Yoshiro Amano

Hirofumi Yanase

Michel P Robert

Hien Phu Dang

Masashi Kisaka

Yoshiaki Sonobe

Fuminori Sai

Hiroshi Uchiike

Takashi Nakamura

Yutaka Ozawa

Masayuki Kanamaru

Sumie Takeda

Atsushi Takeichi

Tomoharu Maeno

Toshifumi Kumano

Shusuke Kurihara

Tomokazu Suzuki

Kazunari Tsuchimto

Kenjo Ogasawara

Embodiments of the present invention provide a magnetic disk device and a method for production thereof, the magnetic disk device being characterized in that the magnetic disk therein permits a plurality of tracks thereon to record correction data when necessary without decreasing its storage capacity. According to one embodiment, the magnetic disk device is characterized in that the magnetic disk has the first tracks and the second tracks formed thereon, the first tracks having servo data regions arranged cyclically, with a portion of a region between them being the correction data region and the remaining regions being the user data region, and the second tracks having the servo data regions arranged cyclically, with the region between them being the user data regions, and the multiprocessing unit (MPU) switches the servo extraction timing of the position information sampler depending on whether the track for servo reproduction by the magnetic head is the first track or the second track.

Disk drive device and method for production thereof

A process, apparatus, and system are disclosed for inhibiting erroneous control signals due to disruptive electromagnetic signals. In one embodiment, the invention prevents erroneous information writing in a recording device under the effect of background electromagnetic waves. A conductor pattern is formed on a printed wiring board on which wiring constituting a control circuit of a hard disk drive is formed. Background electromagnetic waves are detected by an electromagnetic wave detection circuit. In the case where an electromagnetic wave signal detected by the electromagnetic wave detection circuit exceeds a predetermined power, voltage, or current threshold, a write gate signal is turned off to inhibit a potential write operation.

Recording device and controller and control method for a recording device

The read/write offset between the read head and write head is used to determine the head width ratio between the read head width and write head width. The servo information is written onto the magnetic disk in accordance with the APC value and track pitch that are derived from the determined head with ratio.

Servo information write method, data storage device, and programs

Disclosed is a data storage device to provide servo patterns of a track pitch individually consistent with head characteristics (writing width, and reading width) in a recording medium of a hard disk device. The data storage device is provided with a disk having pitch information indicating a track pitch recorded in a predetermined area, and a head for scanning the disk to read the TPI ID and reading/writing data from/in the disk by being subjected to seeking control based on the TPI ID. The TPI ID is recorded as a part of a servo pattern in a TPI ID embedded area provided in an outer periphery of a data area of the disk.

Data storage device, recording medium, servo writing method, and data reading/writing method

A position control system for a magnetic head improves servo tracking characteristics in a low frequency range without impairing the stability of seek operations. The position control system is equipped with two integrators: a first integratorand second integratorThe gain K' of the second integratoris set larger than the gain Kof the first integratorThe first integratorplays the role of offsetting the bias force acting on the magnetic head while the second integratorplays the role of improving the servo tracking characteristics in the low frequency range.

Disk drive apparatus, head position control method, and hard disk drive

A mechanism to allow accurate control of the position of a magnetic head even if the state of the magnetic head has changed due to instability.

Positioning control mechanism for a magnetic head in a magnetic storage device

A disk drive system, includes a head, a controller for controlling an operation of the head, at least one feedback filter coupled in relation to the controller, and a mechanism for keeping a function of the at least one of the feedback filter active during any of an absence of a valid position error signal (PES) and a position error signal being unavailable due to a defect during an operation of the head.

Method and apparatus for sustaining feedback filter state having periodic output

A method to enable servo information to be detected surely and stably even when a time interval between servo sectors is changed due to disk shifting. A time interval TS(i) is calculated according to an internal variable value, which is in proportion to a displacement &Dgr;r(i) of a servo area SF(i) in a radial direction of a subject disk (step S6). The displacement &Dgr;r(i) is calculated from already detected servo information&lsqb;, thereby&rsqb;. Thereby, a time interval for detecting servo information is adjusted according to the above described time interval TS(i) (steps S7 and S4). The time interval TS(i) is the time interval between passing of a servo sector in the servo area SF(i) under the head H and passing of a servo sector in the servo area SF(i&plus;1) under the head H.

Method for controlling servo information detection timing and rotational speed of disk, and disk drive

A method and system for reducing positioning noise in a data storage system are provided. An access device is positioned over a data storage medium using a stream of bursts stored on the medium. The bursts are sensed at a frequency determined by the rate at which the medium is moved relative to a sensing device. Output positioning values are provided to position the access device at a frequency higher than the frequency at which the positioning bursts are sensed, and/or at random times. The random times may be calculated as random advances or delays from time points occurring at a fixed frequency.

Increased and randomized output sampling to reduce positioning noise in a data storage system

A disk drive with means to prevent accidental landing of a head/slider on the disk surface is described. In one embodiment a shock sensor is provided to sense external shocks received by the mechanism. During loading (positioning) of the actuator bearing the head/slider over the disk, if a shock is sensed, loading is stopped and an immediate unloading is performed to return the actuator to the withdrawn position. In another embodiment the unload operation is performed when the rotational speed of the disk is changed. In another embodiment the unload operation is performed when the rotational speed of the disk drops below a threshold. A circuit and method for detecting when the rotational speed of the disk drops below a threshold is also provided. The unloading in the various embodiments may be performed using velocity control or without velocity control.

Disk drive with actuator load/unload controller

The present invention is an apparatus and method to reliably unload a head slider from a recording medium. Transistor Tr5 is on. If the main power supply Vdd is turned off at time t1, Tr1, Tr2, and D1 are turned off and the level of the control signal Ret becomes higher than the threshold voltage Vth of Tr3 and Tr4, turning on Tr3 and Tr4. C1 also starts to discharge. The control signal InRet changes to a 'L'-level, and the control signal OutRet remains to be at the 'L'-level. This allows the IR driver to feed a negative-polarity VCM current through the voice coil to preliminarily move the head arm in the direction opposite to the unload direction. Then, at time t2 when the level of Ret becomes equal to or lower than Vth, both InRet and OutRet change to a 'H'-level, the IR driver becomes inoperative, and the OR driver feeds a positive-polarity VCM current through the voice coil to reverse the moving direction of the head arm.

Head mechanism control apparatus, disk drive unit, and method of

A magnetic recording disk of a disk drive apparatus is constructed having a radially sloped surface, so that the outer area of the disk is thinner than the inner area. The radially downward slope of the disk surface has the effect of increasing the crown of the disk head, this effect being greatest closest to the disk axis and decreasing as the head moves toward the outer diameter. A head landing zone is preferably located at the inner part of the disk surface, where the crown is greatest, reducing stiction during disk start-up. Furthermore, the gradual reduction in crown as the head moves radially outward compensates for the increasing velocity of the head relative to the disk surface, achieving a more uniform flying height of the disk head.

Magnetic disk and magnetic disk apparatus having an annular start-stop

The present invention determines whether a filter is used for reading and writing on a disk to correct repeatable runout. The invention estimates the magnitude of repeatable runout for each disk by measuring the maximum absolute value of a state variable of a filter when the disk is turned on or when the disk returns from a sleep mode, and compares the measured value to a predetermined criterion such as the track width. If the magnitude of the repeatable runout is less than or equal to the predetermined criterion, the filter is not used. If the magnitude of the repeatable runout exceeds the predetermined criterion, the invention reads and writes data using the filter.

Disk drive servo control system with selectable filtering for reduction

For a slider having convex curvature along its length, or 'crown', a method for reducing fly height variation due to crown by shifting the peak of the crown toward the leading end, and the resultant slider structure. In a preferred method, peak shifting is accomplished in a slider with symmetrical crown by affixing a suspension to the bonding surface of the slider near the leading end. The bonding process creates a displacement force upon the slider to effect the shift. An alternative approach reshapes a row of sliders prior to rail shaping, e.g., by sand or bead blasting.

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Chigasaki, Japan

Nobuyuki Kitazaki