Other

International Business Machines Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Jay Francis Raley

Jen-Yuan Chang

Donald Dean Pence

In one illustrative example, a method for use in reducing Repeatable Run Out (RRO) error in a data storage device involves obtaining an RRO measurement for each track of a limited number of N disk tracks; characterizing the RRO measurement for each track with real and imaginary values by performing a discrete Fourier transform (DFT) calculation on each RRO measurement; performing a least-squares fit on all of the real values to identify a first set of (n+1) coefficients of an nth-order polynomial function which is a function of disk track r and representable in the form A(r)=ar+ar+ . . . +ar+a; and performing a least-squares fit on all of the imaginary values to identify a second set of (n+1) coefficients of an nth-order polynomial function which is a function of disk track r and representable in the form B(r)=br+br+ . . . +br+b. RRO compensation is performed based on the relation D(r, s)=&#x3a3;{A(r)cos(i(s2&#x3c0;/total_sectors))+B(r)sin(i(s2&#x3c0;/total_sectors))} where Dis the estimated RRO error; r is a track number; s is a sector number at track number r; i is an RRO harmonic number; H is a set of harmonics to be compensated; and total_sectors is a total number of sectors along track number r. Advantageously, RRO variations across the disk can be accurately compensated for with use of a small amount of memory.

Repeatable runout (RRO) compensation methods and apparatus for data storage devices

A manufacturing test method and apparatus for testing devices, preferably magnetic disk drives, assembled or processed at ones of a plurality of stations in a variegated process stream from components originating from a plurality of sources of components, to determine failure statistics for selected ones of the plurality of stations or ones of the sources of components. The method comprises establishing a unit history record for each device, the unit history comprising entries for indicating the stations at which the device has been processed and the sources of components specific to the device; detecting the results of selected test/operation processes for devices in the stream; reading the unit history record for the device for which the results were detected to determine a 'trace to' stations at which the device has been processed; logging the detected results, by updating a log for each of selected ones of the test/operation process and stations at which a device was processed as determined from the unit history record for the device, with the detected results for the device; calculating at least one 'trace to failure' statistic for selected ones of the results and/or stations; updating the unit history record with the results for the device; and comparing the 'failure' statistic to an alarm threshold and actuating an alarm if the threshold is exceeded.

Variegated manufacturing process test method and apparatus

The invention is a fluid distillation apparatus (10) which, in its preferred embodiment, includes a cylindrical portion (12) which mates with an end wall (14) and a bell portion (16) to form an enclosed volume (18) within which evaporization and condensation of a selected fluid may take place. A heat exchange rotor assembly (20) is formed of head conductive material and includes intertwined evaporization and condensation channels (52, 54) in spiral array. A central tunnel (58) provides access for vapor from an evaporization volume (24) to a condensation volume (26) with a pressure gradient provided by an impeller (100) urging such passage. A drum motor (68) rotates the drum (40) to facilitate liquid flow in the heat exchange rotor (20). An impure fluid input port (32) and output ports are provided for purified fluid (34), concentrated brine (36) and degassing purposes (38). The apparatus is a flow process device and is especially adapted for continuous purification, such as water distillation or desalinization.

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San Jose, CA, United States of America

Jay Francis Raley