Patent ID: 6817560
Filing Date: 2004-11-16
Classification: G11B

Abstract:
A tension control system for providing dynamic tension control for tape transported along a tape path between a supply reel and a take-up reel, said supply reel driven by a supply reel motor, said take-up reel driven by a take-up reel motor, comprising:a supply tachometer for measuring the rotational angular displacement of said supply reel; a take-up tachometer for measuring the rotational angular displacement of said take-up reel; and a controller for operating said supply reel motor and said take-up reel motor, said controller: upon accelerating said tape toward a target tape speed; initially operates said supply reel motor and said take-up reel motor in static acceleration tension control; measures said rotational angular displacement of at least one of said supply reel from said supply tachometer, and of said take-up reel from said take-up tachometer; determines from said measured rotational angular displacement, the rotational angular velocity of at least one of said supply reel and said take-up reel; determines from said rotational angular velocity, a linear speed for said tape; if said linear speed of said tape is less than a predetermined range of said target tape speed, continues said static acceleration tension control; if said linear speed of said tape is within said predetermined range of said target tape speed, operates said supply reel motor and said take-up reel motor in composite tension control employing static tension control and delta velocity control; said delta velocity control comprising said controller: measuring said rotational angular displacement of said supply reel from said supply tachometer; measuring said rotational angular displacement of said take-up reel from said take-up tachometer; determining from said measured rotational angular displacement of said supply reel, the rotational angular velocity of said supply reel; determining from said determined rotational angular velocity of said supply reel, a linear speed for said tape at said supply reel; determining from said measured rotational angular displacement of said take-up reel, the rotational angular velocity of said take-up reel; determining from said determined rotational angular velocity of said take-up reel, a linear speed for said tape at said take-up reel; comparing said determined linear speed for said tape at said supply reel to said determined linear speed for said tape at said take-up reel, to determine a delta velocity between said linear speeds; and operating at least one of said supply reel motor and said take-up reel motor in accordance with a function of said delta velocity to provide a torque to at least one of said supply reel and said take-up reel tending to reduce said delta velocity.