Tracking control for recorder-reproducer systems with the control transducer located at the neutral point of the tape stretch

Claim 1

The combination with a reproducer system having a guide surface and means for transporting in tension an elongated record web through a path on and in frictional relation with said guide surface between first and second points defining respective entry and exit points of said web on said surface, said transport means including means for establishing a predetermined tension in said web at said first point with a further greater value of tension at said second point being determined by The extent of the path of said web on said surface and the frictional relation between said web and said surface, to thereby produce a given amount of stretch of said web on said surface, and moveable transducer means for scanning information tracks extending transverse of said web, a control arrangement for minimizing the effective mistracking of said information tracks by said moveable transducer means, comprising; stationary transducer means for transducing control information longitudinally of said web said stationary transducer means arranged to cooperate with said web at a further point between said first and second points on said surface, the position of said further point being such that the amount of resulting stretch of the portion of said web between said first and said further point is substantially equal to the amount of stretch of the portion of said web between said second and said further point; said guide surface is arcuate; the relative differential tension of said web on said surface between said entry and exit points are related by the equation Tout Tin . e ; the resulting stretch S of said web on said surface is defined by the equation S Tin R (e -1)/ Mu EA ; and the angular position theta p of said control transducer means, as measured from said entry point is defined by the equation theta p 1/ Mu 1n (e + 1)/2 wherein, theta is the angle of wrap of said tape about said arcuate guide surface, R is the effective radius of curvature of said arcuate guide surface, Mu is the effective coefficient of friction between said web and said guide surface, A is the area of the cross-section of the elongated record web, and E is the value of Young''s Modulus for the record web.