Arun Sharma, 44Chappaqua, NY

6339512, Jan 15, 2002

Mar 25, 1999

09/276211

S. M. Sri-Jayantha - Ossining NY
Hien Dang - Nanuet NY
Arun Sharma - New Rochelle NY
Kiyoshi Satoh - Fujisawa, JP
Tetsuo Ueda - Sagamihara, JP
Hideki Ohzeki - Yokohama, JP
Nayouki Kagami - Fujisawa, JP
Kiochi Takeuchi - Yamato, JP

International Business Machines Corporation - Armonk NY

G11B 5596

360 7704, 360 65, 360 7809

A hard disk has a servo loop and a rotating storage medium. The rotating storage medium has one or more significant flutter modes at frequencies below a zero cross frequency of a rejection transfer function of the servo loop. The effect of the forgoing is to allow the servo loop to better track a rotating medium that is subject to significant flutter. Peak filters with frequency bands that substantially overlap frequency bands of the significant flutter modes can also be added to the servo loop to further improve tracking. Multiple narrow band filters with frequency bands overlap can be used to cover the spectrum of a single flutter mode. Two lag-lead filters, the frequency responses of which overlap can be used to cover two adjacent significant flutter modes. At frequencies intermediate to the two adjacent flutter, modes, the lead caused by one filter, will be cancelled by the lag caused by the second.

6344943, Feb 5, 2002

Mar 29, 1999

09/280384

Nobuyuki Kitazaki - Kanagawa, JP
Kiyoshi Satoh - Ayase, JP
Arun Sharma - New Rochelle NY
Sri Muthuthamby Sri-Jayantha - Ossining NY
Isao Yoneda - Yokohama, JP

International Business Machines Corporation - Armonk NY

G11B 5596

360 7814, 360 7804, 360 7808, 711112

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.

6377418, Apr 23, 2002

Sep 3, 1998

09/148846

Naoyuki Kagami - Fujisawa, JP
Akira Tokizono - Fujisawa, JP
Hien Dang - Nanuet NY
Arun Sharma - New Rochelle NY
Sri M. Sri-Jayantha - Ossining NY

International Business Machines Corporation - Armonk NY

G11B 5596

360 7814, 360 39, 360 75

The present invention provides a digital filter which is capable of preventing filter outputs from being discontinuous when a filter characteristic is changed. Initially, a servo assistant (SA) computes parameters for computing servo data, and based on the computed parameters, the SA judges an operating mode. If the mode has been changed, the SA will advance in processing. Next, the parameters of a filter are changed in correspondence with the judged operating mode, and the initial values of the interior variables of the filter are set to appropriate values.

6487028, Nov 26, 2002

Mar 25, 1999

09/275952

S. M. Sri-Jayantha - Ossining NY
Hien Dang - Nanuet NY
Arun Sharma - New Rochelle NY
Kiyoshi Satoh - Fujisawa, JP
Tetsuo Ueda - Sagamihara, JP
Hideki Ohzeki - Yokohama, JP
Nayouki Kagami - Fujisawa, JP
Kiochi Takeuchi - Yamato, JP

International Business Machines Corporation - Armonk NY

G11B 502

360 25, 360 7704

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.

6567230, May 20, 2003

Oct 28, 1999

09/429696

Naoyuki Kagami - Fujisawa, JP
Akira Tokizono - Fujisawa, JP
Sri M. Sri-Jayantha - Ossining NY
Tatsuya Sakai - Yamato, JP
Isao Yoneda - Yokohama, JP
Hien Phu Dang - Nanuet NY
Arun Sharma - New Rochelle NY

International Business Machines Corporation - Armonk NY

G11B 2102

360 75, 360 65

A method and system for utilizing a digital filter for actuator positioning control in a disk device. In accordance with the method and system of the present invention multiple selectable filter modules are provided. Each of the multiple selectable filter modules functions in a serial or parallel filtering mode when selected. Multiple configurable registers are also provided wherein the configuration of each of the multiple configurable registers determines a selection of at least one of the multiple selectable filter modules. Particular ones of the multiple configurable registers are selected, such that a configuration of the digital filter is dynamically selectable in order to achieve a predetermined filter output.

6532129, Mar 11, 2003

Jun 11, 1999

09/330180

Sri Muthuthamby Sri-Jayantha - Ossining NY
Hien P. Dang - Nanuet NY
Arun Sharma - New Rochelle NY
Isao Yoneda - Yokohama, JP
Nobuyuki Kitazaki - Kanagawa, JP

International Business Machines Corporation - Armonk NY

G11B 5596

360 7702

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.

6574065, Jun 3, 2003

May 14, 1999

09/311307

Sri M. Sri-Jayantha - Ossining NY
Arun Sharma - New Rochelle NY
Hien Dang - Nanuet NY
Tetsuo Ueda - Sagamihara, JP
Kenji Okada - Yokohama, JP
Hideo Asano - Machida, JP
Tatsuya Endoh - Fujisawa, JP
Masayuki Takeuchi - Kamakura, JP

International Business Machines Corporation - Armonk NY

G11B 2102

360 75

A method and apparatus for adaptive resonance cancellation in a rotating storage system, includes designing a set of digitally selectable optimum resonance cancellation filters, generating a series of excitation signals for injection into the filters, generating a characteristic resonance frequency based on the excitation signals, and computing an address pointer corresponding to the resonance frequency, to select an optimum resonance cancellation filter.

6683745, Jan 27, 2004

Dec 27, 1999

09/472175

Sri M. Sri-Jayantha - Ossining NY
Vijayeshwar Das Khanna - Millwood NY
Gerard McVicker - Stormville NY
Hien Dang - Nanuet NY
Arun Sharma - New Rochelle NY
Kiyoshi Satoh - Fujisawa, JP
Tatsuo Nakamoto - Sagamihara, JP

Hitachi Global Storage Technologies Netherlands B.V. - Amsterdam

G11B 1700

360 9701, 360 9702

A system for mounting a hard disk enclosure (HDE), includes a casing pivotably mounted to minimize at least one of settle-out dynamics, external rotational vibration, and emitted vibration, the casing allowing the HDE to rotate substantially freely, wherein the center of gravity of the HDE is substantially the same as a pivot point of the casing. Further, a computer chassis includes a housing, at least one disk drive assembly for being housed by the housing, and a plurality of theta-mounts integrally built within the housing.