Patent ID: 7458326

Claim:
An overlock sewing machine forming overlock stitches by swinging an overlooper and an underlooper in synchronization with a vertical movement of a sewing needle, the overlock sewing machine comprising: a main shaft rotated by a sewing machine motor and vertically driving the sewing needle; a looper drive shaft having a shaft line perpendicular to the main shaft and rotated by the rotation of the main shaft; a swing generating member fixed to the looper drive shaft and having a first swing generating portion for swinging the overlooper and a second swing generating portion for swinging the underlooper; a first swing link mechanism arranged in a direction perpendicular to the looper drive shaft and swinging the overlooper by conveying thereto a drive force generated by the first swing generating portion; and a second swing link mechanism arranged in a direction perpendicular to the looper drive shaft and swinging the underlooper by conveying thereto a drive force generated by the second swing generating portion, wherein the first swing generating portion comprises a crank pin eccentric with respect to the looper drive shaft, and the second swing generating portion comprises an eccentric ring eccentric with respect to the looper drive shaft; the swing generating member being integrally provided with the crank pin and the eccentric ring.