Seagate Technology Incorporated

Aurora Lighting, Inc.

James W Dulaney

Ryan Todd Lyle

Wonbo Shim

Roy Lynn Wood

Moshe Shloush

Jason Dale Gregg

David Charles Waugh

Jeffrey Don Andress

Matthew Glenn Duvall

Jeffery D Andress

Method and apparatus for performing a seek operation to move a data transducing head from an initial track to a destination track on a rotatable recording surface. A servo control circuit operates to sweep the head across the recording surface. Servo data from an intermediary track are transduced to obtain a detected angular position value for the head with respect to the recording surface. When the detected angular position value differs from a predicted angular position value for the head, the servo control circuit initiates an index qualification routine at the conclusion of the seek. The qualification routine involves transducing the servo data from the destination track to verify the accuracy of the predicted angular position value. In this way, the effects of spurious (false) index signals obtained from the servo data transduced during the seek operation are minimized, and unnecessary reinitializations of the servo control circuit are avoided.

Adaptive index reference position qualification

Method and apparatus for reducing and dispersing wear to the surface of a rotatable disc in a disc drive using an adaptive dither process. The disc drive includes an actuator assembly that is secured in a parked position by a latch when not in use. The method includes determining an open latch current required to open the latch as the actuator assembly is moved from the parked position to a position over a user data storage portion of the disc. A dither current is subsequently applied to the actuator assembly to induce a reciprocating lateral displacement of the actuator assembly when the actuator assembly is secured in the parked position, wherein the maximum amplitude of the dither current is selected to be less than the open latch current.

Wear reduction of a disc surface using an adaptive dither process

Method and apparatus for improving data transfer rate performance of a disc drive data handling system having a plurality of transducing heads adjacent a corresponding plurality of data recording surfaces. Concentric tracks on each of the recording surfaces are provided with a physical track address determined by servo data written to each track. Logical track addresses are assigned to the tracks by positioning a first head adjacent a selected location on the corresponding recording surface, measuring a head offset value for each of the remaining heads, and assigning the logical track addresses on each data recording surface in relation to the measured head offset values. The logical cylinders include tracks with different physical track addresses, and the tracks in each logical cylinder are nominally aligned with the heads. This reduces the need for corrective seeks after head switching within the same logical cylinder.

Adapting logical track addresses in relation to head offsets

An electronic ballast operates a gaseous discharge lamp. The electronic ballast includes a filter circuit for removing noise from an electrical power signal. The power factor of the filtered power signal is adjusted by a power factor correction circuit. The power factor correction circuit includes a programmable inductor circuit having a plurality of selectable inductance values for varying the amount of power factor adjustment to accommodate operation of different lamp types and/or different lamp wattages. A power supply circuit converts electrical power received from the filtered power signal to provide low level power for operating the electronic ballast. An output circuit receives the corrected power signal produced by the power factor correction circuit and produces an electrical signal to ignite and operate the discharge lamp. The output circuit includes an ignition circuit for producing an oscillating voltage signal to ignite the lamp, and an operating circuit produces an oscillating current signal which operates the discharge lamp after ignition. A control circuit controls the operation of the electronic ballast. A current monitor is used to determine when the lamp is ignited. The ability of the electronic ballast to accommodate different lamps is enhanced by providing the ignition circuit with a programmable inductor circuit to oscillate the voltage signal at different frequencies. A similar effect is achieved by providing the operating circuit with a programmable resistor circuit having a plurality of programmable resistance values.

Electronic ballast for discharge lamps

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Oklahoma City, OK, United States of America

James W Dulaney