| 摘要 |
A mechanism for driving needles of a sewing machine to produce for example a two thread interlocked chain stitch. To a frame is mounted a pair of eccentric cams for rotation generally about 180 DEG out of phase with each other about an axis, the cams having peripheral bearing surfaces of predetermined contour. The shape of the peripheral bearing surfaces of the eccentric cams and of inner and exterior bearing surfaces on circumscribing cam cage followers, and the position of edge guides positioned about the outer surface of the cam cage followers so as to bear against parts of the cam cage followers, are such as to provide relative movement and orientation of each cam cage follower in a complete cycle to permit sewing machine needles associated with the cam cage followers to stitch a chain stitch. The mechanism according to the present invention permits sewing of broad fabrics by a single head unit without a cantilever arm, since a looper, located on the opposite side of the material being sewn is not required. From a single rotary input driving shaft, relative needle movement may be achieved with exact kinematic control, using no gears, chains or timing pulleys as required on traditional, known types of sewing machine needle drive mechanisms.
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