PROCEDIMENTO DI,E DISPOSITIVO PER LA,RIVELAZIONE DELLA ESTREMITA' DEL FILO SUUNA BOBINA

A method and device for detecting the yarn end on a bobbin in a textile machine. The textile machine comprises a plurality of operating units situated next to each other and an attending device adapted to travel along the units and to stop at a selected one of the operating units. The attending device includes a selecting device provided with a detecting nozzle having a yarn sucking mouth. The detecting device is displaced into a detecting position in which the mouth of the detecting nozzle lies in the path of possible motion of a central tube of the bobbin. The bobbin begins to move towards the mouth of the detecting nozzle situated in its detecting position onto which the bobbin circumference comes to lie. The mouth of the detecting nozzle then moves in the direction of the bobbin motion whereupon the bobbin stops and then begins to move in the reverse direction while the mouth of the detecting nozzle remains in contact with the bobbin circumference up to the return of the detecting nozzle into its detecting position where the mouth of the detecting nozzle stops. The moment that contact is lost between the bobbin circumference and the mouth of the detecting nozzle is monitored. The bobbin moves from the detecting position for a given time interval, ensuring a constant distance between the bobbin circumference and the mouth of the detecting nozzle, regardless of the yarn winding diameter on the bobbin.