Method for positively feeding an elastic yarn, and circular knitting machine

In a circular knitting machine comprising at least one positive yarn feeder apparatus for feeding an elastic yarn to a knitting system, an electronic control unit for said positive yarn feeder apparatus operatively connected to an electric drive motor of said yarn feeder apparatus, said electric drive motor being operative to cause said yarn feeding apparatus to positively feed said elastic yarn to the knitting system, at least one signal generator connected to said control unit and associated with a yarn guide for generating a yarn leadin signal and a yarn take-out signal in response to said yarn being led into or taken out of said knitting system, respectively, said control unit including means responsive to said yarn lead-in signal and said yarn take-out signal for normally respectively generating a start signal and a stop signal which respectively actuate and de-actuate said drive motor, a position signal generator connected to said control unit for generating regular position signals in response to the operation of said circular knitting machine, and a speed control section in said control unit for controlling the operating speed of said drive motor in response at least to said position signals, the improvement wherein the connection for transmitting said start and stop signals between said control unit and said drive motor includes an adjustable delay circuit means activated by said yarn take-out signal for adjustably delaying the generation of said stop signal and the corresponding de-actuation of said drive motor for a selected space of time after the generation of said yarn take-out signal, said delay circuit means being operable to generate said stop signal and to apply it to said drive motor as soon as said preselected space of time has expired.