Two speed loop control arrangement

In control apparatus for providing controlled movement of a flexible strip-like recording medium between a supply location from which the strip is withdrawn at a uniform rate and a takeup location to which the strip is advanced at a nonuniform rate, the improvement comprising:

• means for driving the strip at a sufficient speed to at least establish and maintain a buffer loop between the strip supply location and the strip takeup location;
• means responsive to the drive means for producing a speed signal indicative of the speed at which said drive means is operating;
• control means responsive to variations in the size of said buffer loop for producing a loop signal to control the speed of said drive means to establish and maintain said loop at a selected size, said control means being operable in either a first relatively fast mode of response or a second relatively slow mode of response to provide said loop signal, said control means also comprising:
• means for transferring control of the speed of said drive means between said fast mode of response and said second slow mode of response without substantial immediate change in the level of said loop signal;
• and
• speed regulation means responsive both to said speed signal and said loop signal for maintaining the speed of said drive means.

In control apparatus for providing controlled movement of a flexible strip-like recording medium between a supply location from which the strip is withdrawn at a uniform rate and a takeup location to which the strip is advanced at an intermittent rate, the improvement comprising:

• means for driving the strip at a sufficient speed to at least establish and maintain a buffer loop between the strip supply location and the strip takeup location;
• sensor means responsive to variation in the size of said buffer loop for producing an output which changes between two levels indicative of whether the loop size is above or below a selected size and with a time period corresponding to the period of said intermittent advancement and with a duty cycle corresponding to the time that the loop size differs from said selected size;
• means for converting the duty cycle of said changing output to a corresponding signal level;
• and
• means for controlling the speed of said drive means as a function of said signal level to substantially maintain said loop at said select size.

Control apparatus for providing uniform motion synchronized with the average speed of an intermittent motion, said apparatus comprising:

• supply means for paying out first and second elongated flexible elements at the same rate;
• a first station receiving at least said first element;
• intermittent motion means for advancing at least said first element step-wise past said first station at a nominal rate;
• a second station receiving at least said second element;
• element-engaging drive means for continually advancing at least said second element past said second station at a rate corresponding to said nominal step rate;
• return means for taking up said elements at the same rate;
• means for introducing a buffer loop into at least said second element to isolate the portion thereof at said second station from said intermittent motion;
• loop sensor means for providing an output that changes between two levels indicative of the size of said loop relative to a select size;
• means for generating a signal level corresponding to the duty cycle of said loop sensor output;
• means for integrating the signal level corresponding to the duty cycle of said loop sensor output at one of two selectable integration rates;
• switching means responsive to the loop sensor output for initially selecting the faster rate and for selecting the slower rate in response to a selected condition of said loop relative to said selected loop size;
• means for producing a speed signal indicative of the speed at which said drive means is operating;
• and
• speed regulation means responsive to said speed signal for maintaining the speed of said drive means in accordance with the output of said integrator means.