Method of, and device for, detecting the yarn end on a bobbin

A method for detecting a yarn end on a bobbin having a central tube and supported in a winding device of an operating unit of a textile machine, wherein the textile machine comprises a plurality of operating units situated next to each other and comprises an attending device which attends to a selected operating unit at which there is a yarn interruption, and the attending device is fitted with a detection device provided with a detecting nozzle having a yarn sucking mouth, the method comprising:

• displacing the detecting device over the textile machine and into a detecting position;
• moving the mouth of the detecting nozzle to lie in the path of possible motion of the central tube of the bobbin;
• moving the bobbin in one direction toward the mouth of the nozzle, such that when the bobbin mounted in the winding device moves toward the mouth of the detecting nozzle which is in the detecting position, and when the circumference of the bobbin comes to lie on the mouth, the bobbin moves against the mouth of the nozzle, the mouth of the nozzle is moved along with the bobbin in the direction of the motion of the bobbin;
• upon contact between the bobbin and the mouth of the nozzle, stopping the movement of the bobbin in the one direction and moving the bobbin in the reverse direction wherein the mouth of the nozzle is remaining in contact with the circumference of the bobbin until the mouth of the nozzle has returned to the detecting position;
• then stopping the reverse direction motion of the nozzle which is moving along with the return of the bobbin while reverse motion of the bobbin continues;
• monitoring the moment of the end of the contact between the bobbin circumference and the mouth of the nozzle;
• then moving the bobbin away from the mouth of the nozzle for a predetermined time interval, for thereby assuring there is a constant distance between the circumference of the bobbin and the mouth of the detecting nozzle regardless of the winding diameter of the yarn on the bobbin.