At present, most traditional self-winding machines do not have yarn position control, and they are all set by time in the process of catching the yarn end. After the yarn ends are caught, the extra setting time will cause more length of yarn to continue to be sucked in, and vice versa, If the set time is too short, the success rate of head catching will decrease. In order to maximize the yarn splicing control and reduce the amount of yarn waste, the yarn end sensor control technology is used in the advanced modern self-winding machine. This design is equipped with a yarn end sensor device in the yarn catcher of the winder. When the yarn end is sucked into the suction arm and reaches the photoelectric sensor device, it will send a signal to continue the next action and close the damper to save money. Energy consumption. no The previous action will be maintained until the yarn end is reliably caught. When splicing, once the yarn end is caught, the sensor can immediately send a signal for splicing action, and the yarn catching arm no longer has repeated movements to reduce splicing time and yarn waste. The yarn length of each splicing can be controlled at 50 cm~60 cm, which can greatly save yarn waste. The same principle, for example, after the yarn clearer cuts the yarn, after accurately measuring the position of the yarn end, the length of the detected defective yarn can be completely absorbed to ensure that the yarn is in the package. No defect yarn.