Patent ID: 6836386
Filing Date: 2004-12-28
Classification: G11B

Abstract:
A tape velocity calibration system for a tape drive, said tape drive having a plurality of DC motors, said DC motors each arranged to longitudinally move a tape mounted on tape reels rotated by said DC motors under the control of a motor driver servo system, said motor driver servo system computing velocities of each of said DC motors for given longitudinal tape velocities; said velocity calibration system comprising:at least one Hall sensor at each of said DC motors for sensing the states of said DC motors; and logic for operating said DC motors, said logic: operating each of said DC motors under separate control at steady state computed estimated velocity (Omega C) for at least one full revolution without a tape; sensing said at least one Hall sensor to indicate a full revolution of each of said DC motors; measuring the time of said full revolution of each of said DC motors; determining the actual velocity (Omega A) of each of said DC motors by dividing said measured time of said full revolution of each of said DC motors into 2 times pi; determining a calibration constant (K calib) for each of said DC motors by comparing said computed estimated velocity (Omega C) during said full revolution, to said determined actual velocity (Omega A); and for said motor driver servo system, providing said calibration constants (K calib) for each of said DC motors for calibrating the motor velocity of each said DC motor, whereby said motor driver servo system determines a longitudinal tape velocity for a tape mounted at said tape drive by averaging the tape velocity generated by each of said DC motors based on said calibrated motor velocity.