Noncontact measurement of the quantity of remained thread of a sewing machine used in the factory

The research and development of equipment to detect that the thread on the bobbin becomes a small quantity have been performed. The specific pattern of the remained thread appears, when the thread decreases. In this paper, the detecting method using this pattern was proposed, and the operating characteristic of equipment is reported. The infrared ray was emitted to the optional place of the bobbin with thread and the output signal from the logic circuit was detected. Experiments on performance of amplification and discrimination circuit showed that the developed noncontacting equipment for measuring the remained thread was normally operated.