| 摘要 |
A sewing machine including a needle that is supplied with an upper thread. A a reciprocating movement carries the upper thread through a sewing material and forms a loop beneath the sewing material. A shuttle houses a bobbin for lower thread and a shuttle arm catches the loop of the upper thread and carries the upper thread around the lower bobbin, so that a stitch is executed on the sewing material. A thread feeder feeds the upper thread to the needle and a control element on each stitch causes the thread feeder at the beginning of a stitch to advance a predetermined length of upper thread, including an excess thread, and at the end of the stitch to correct the length of the upper thread by recovering the excess upper thread, or advancing the further upper thread required. |
