International Business Machines Corporation

Fairtron Corporation

Thomas C Christensen

Earl Albert Cunningham

Dana H Brown

Wayne A Rogelstad

Jodie Ann Christner

Jonathan Darrel Coker

Weldon Mark Hanson

Mark David Hagen

David Timothy Flynn

Douglas Edward DeVries

Michael L Workman

Donald Earl Vosberg

Mark Andrew Bergquist

Gregory J Kerwin

Michael W Walter

Matthew W Rooke

Jay Michael Mosbrucker

Dean C Palmer

Timothy J Prachar

Richard C Jaworski

James Joseph Mosser

Jacques Y Foster

Alan S Foster

Jack L Carter

William G Phelps

Daniel W Smith

Jeffrey R Roepke

A self servo writing file and method for writing servo patterns in a direct access storage device are provided. First servo information is written on a data storage media at a first crash stop. The transducer heads are moved offset from the written servo information while reading the last written servo information until the detected servo signal equals a predetermined value. Then servo information is written on the data storage media responsive to the detected servo signal equal to the predetermined value. The moving and writing steps are sequentially repeating until a second crash stop is reached. A quad-burst servo amplitude pattern or phase pattern can be used for the servo information. The servo writing method is adapted easily for many different servo options. When the file uses a hybrid servo or sector servo, the other surfaces can be written by duplicating the servo bursts with a high bandwidth servo system of the file. Alternatively, the servo writing steps can be repeated for each of the other surfaces for providing head dependent pitch. Variable track pitch can be provided by selectively varying the predetermined value compared with the detected servo signal.

Self servo writing file

A multipath channel apparatus for a data storage device wherein data is stored on a storage medium and is read from the storage medium by a transducer or for a data communications system wherein data is transmitted to a receiver. A data channel having a plurality of data paths is operatively connected to the transducer to receive data read from the storage medium by the transducer, or operatively connected to receive data demodulated by the receiver or base band data received by the receiver. Preferably, each of the data paths has a differing parameter value. An error checking unit checks customer and redundancy data from each of the data paths. A selecting unit, which is responsive to the error checking unit, selects data from one of the data paths. In a preferred embodiment, the data stored on a storage medium includes a data field and an error correcting code field, and the customer and redundancy data from each of the data paths is checked using a calculated error correcting code sydrome.

Multipath channel apparatus and method using offset parameters to

A self servo writing file and method for writing servo patterns in a direct access storage device are provided. First servo information is written on a data storage media at a first crash stop. The transducer heads are moved offset from the written servo information while reading the last written servo information until the detected servo signal equals a predetermined value. Then servo information is written on the data storage media responsive to the detected servo signal equal to the predetermined value. The moving and writing steps are sequentially repeated until a second crash stop is reached. A quad-burst servo amplitude pattern or phase pattern can be used for the servo information. The servo writing method is adapted easily for many different servo options. When the file uses a hybrid servo or sector servo, the other surfaces can be written by duplicating the servo bursts with a high bandwidth servo system of the file. Alternatively, the servo writing steps can be repeated for each of the other surfaces for providing head dependent pitch. Variable track pitch can be provided by selectively varying the predetermined value compared with the detected servo signal.

Self servo writing file using the widest head

A magnetic head including a shielded MR element which incorporates a low reluctance path between the shields to reduce interference picked up by inductive reading of the shields. The low reluctance path is provided outside a conductive loop of material which includes the MR element and its associated leads. The low reluctance path may include a magnetic short between the two shields.

Magneto-resistive head including a selectively placed low-reluctance

A method and apparatus is provided which introduces a relative skew between a servo pattern and a magneto-resistive (MR) head in order to reduce interference introduced by inductive reading of shields formed as part of the MR head. The relative skew may be accomplished by introducing a skew angle directly on the head or by skewing the servo pattern formed on the magnetic medium relative to the head. Various skewed patterns may be used to reduce the overall interference.

Method and apparatus for reducing servo interference in a

A large scale video display of the present invention is designed to receive a standard NTSC video signal and display it on a large scale array of low cost, voltage or current controlled lamp transducers. The video signals are received by a video capture device which receives and digitizes the video signal. A host processor formats the digital data into a number of 16 bit data words each corresponding to a pixel. A coprocessor receives the 16 bit data words and reformats the data. The reformatted data is connected to a large scale display by a fiber optic connection. The display includes a number of transceivers which receive the formatted video data in a memory buffer. The transceivers also receive a board map from the coprocessor. The map indicates which light boards correspond to each part of the memory where the frame image is stored. This information is used by a number of controllers to determine which lights to turn on and at what level of brightness for any given time.

Real time low cost, large scale array 65K color display using lamps

Multipath channel apparatus and method for data storage devices and

The present invention demonstrates a rotating media storage system which quickly measures and accurately compensates for thermal and mechanical errors in the position of the data detector with respect to the written data. This is accomplished by measuring the error rate of the written data as a function of the read offset of the detector. Error rates become increasingly large as the sensed noise to signal ratio becomes large. The present invention counts the number of errors detected in reading written data for various read offsets when the data storage system is initially activated. When the number of errors reaches a target rate, the read offset required to produce the target rate is saved. This procedure is performed on either side of the data track. The detector is then centered between the two offsets. During the operation of the storage system, thermal and mechanical errors are introduced into the detector position compensation means. The present invention compensates for this by periodically determining a new offset for each side of the data track. The new offset which corresponds to the target error rate is found by interpolating between measured offsets for error rates which are higher and lower respectively than the target error rate. The new measured read offsets are obtained by reading back written data in a similar manner as was used to obtain the initial read offsets. The detector is then recentered with respect to the write transducer position between the new offsets on either side of the data track.

Functional measurement of data head misregistration

Disclosed is a method for recovering data from a portion of a magnetic surface that contained a read error. After a read error is encountered a magnetic transducer undergoes a head state change. The head state change is accomplished by either writing to a reserve area of the magnetic surface and or reading a portion of the magnetic surface and then rewriting to that portion of the magnetic surface. After the magnetic transducer undergoes a head state change, the portion of the magnetic surface that contained the read error is reread.

Method and apparatus for recovering data

A magnetic disk drive channel circuitry is shown and described that generates eight incremental values of write current and eight incremental values of delta-V (the minimum voltage change per unit time which tests signals to discriminate between data and noise). Each of these variable parameter values may be program selected by a three bit bus signal. This variability testing of an adaptation to the optimum parameter value for each head media combination and by grouping tracks in contiguous data bands, the parameters may be optimized for tracks near the inner diameter, the outer diameter and in the middle band. The variable delta-V can also be used as an additional data recovery tool wherein re-reading with a lower value enhances recovery of missing bit errors and re-reading with an increased value can assist recovery from an extra bit error.

Compensation of write current adn delta-V for recording component and

Growing community of inventors

Rochester, MN, United States of America

Thomas C Christensen