Motor control system with exponential reference source for maintaining a constant lineal speed of a film being wound on a reel

Claim 1

In a film handling apparatus including a drive motor for driving a take-up reel, a motor control system comprising: exponential reference circuit means for providing an exponentially changing speed reference signal correlated to the increasing film convolution diameter as film is wound onto said reel; motor speed feedback means including means driven by said drive motor to produce pulses at a frequency indicative of the actual speed of said drive motor, differentiating means for differentiating said pulses to produce differentiated pulses at a frequency indicative of actual motor speed but of substantially constant time width, and integrating means for integrating said differentiated pulses to produce said feedback signal indicative of actual motor speed; and circuit means for controlling the speed of said drive motor as a function of said speed reference signal and said feedback signal such that the lineal speed of said web toward said reel is constant, said circuit means including summing means for summing said speed reference signal and said feedback signal to produce an error signal indicative of the difference in magnitude between said signals, and amplifier means for amplifying said error signal to produce a motor control signal.