| 摘要 |
The needle-shifting zig-zag unit and the work feeding unit are moved to different positions, when necessary, for successive stitches, to form a stitching pattern. Each unit is powered by the main rotating drive shaft of the sewing machine. However, each unit is provided with a respective stepper motor. Each stepper motor changes the setting of an adjuster in a reciprocating-motion generator driven by the main drive shaft. When one of these adjusters is in a constant setting, its respective reciprocating-motion generator continually generates reciprocating motion of constant corresponding amplitude, for an unlimited time, so long as the drive shaft rotates. The needle-penetration coordinates for the stitching pattern are established by continually changing the amplitude of the reciprocations performed by the two reciprocating-motion generators. A static memory is read out, in synchronism with sewing, to furnish information commanding the stepper motors to move the amplitude adjusters of the reciprocating-motion generators from one amplitude setting to another, very quickly, to in this way establish all the successive needle-penetration coordinates for even complex stitching patterns. |
