TAPE RUNNING DEVICE

PURPOSE:To control a tape running speed (v) to a constant speed during fast winding operation by detecting the number n1 of turns of a take-up reel and the number n2 of turns of a payoff reel and holding (1+n1 +1/n2 ) constant. CONSTITUTION:When the tape runs, the 1st detector 7 outputs a signal corresponding to the number n1 of turns of the take-up reel 1. The 1st computing element 8 processes the output to generate a signal 1/n1 . The 2nd detector 9, on the other hand, generates a signal corresponding to the number n2 of turns of the supply reel 2, and the 2nd computing element 10 processes this signal to generate a signal 1/n2 . An adder 11 sums up the outputs of the 1st and 2nd computing elements 8 and 10 to generate a signal proportional to (1/n1 +1/n2 ). A comparator 12 compares a speed set value with the output of the adder 11 and an integrator 13 drives a reel motor 14. Namely, the relation between the sum (s) (cm ) of areas of both reels and the tape running speed (v) (cm/sec) is expressed by a specific equation, and while the left-hand side member is held constant, the (s) is constant, so the tape speed (v) is held constant.