Controlled thread clamp device for needle threads

The machine defined in 4 wherein said thread clamp is arranged upon a guide plate formed with thread-guide slits.

In a sewing machine having a thread-uptake lever and a sewing needle, a sewing thread generally passing through an aperture in said lever and an eye in said needle, an assembly for providing at said needle upon the completion of each stitching cycle a pre-established length of a leading portion of said thread, said assembly comprising:

• thread-tension means disposed on said machine between said lever and a thread source for generally engaging said thread to provide same with a predetermined tension;
• thread-clamping means disposed on said machine between said lever and said needle for temporarily clamping said thread during at least a terminal portion of an upward stroke of said lever;
• control means on said machine connected to said thread-tension and thread-clamping means for substantially simultaneously actuating said thread-tension means to release said thread and said thread-clamping means to clamp said thread at a predetermined instant during each stitching cycle, whereby a pre-established length of a leading thread portion is provided at said needle in particular prior to the beginning of sewing a seam.