| 摘要 |
A sewing machine for sewing buttonholes is equipped with a mechanism for swinging the needle (12) to produce a zigzag seam, e.g. having alternate stitches with and without lower thread (67). The feed mechanism (33) for the upper thread (34) has a lever (41) positioned by a stepping motor (45), which is controlled by a position sensor (56) on the needle bar (8) and by a fabric thickness sensor (62).
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