Thread take-up device for a sewing machine

Abstract

A thread take-up device comprising a loop tightening member adapted to reciprocate within a predetermined range limited by a thread slackening limit position where the loop tightening member is located when a thread loop is expanded to its maximum extent by a loop-seizing member, and a loop tightening limit position for tightening the thread loop; and a movable member adapted to reciprocate within a predetermined range limited by a stopping position defined within the range of reciprocation of the loop tightening member above the loop tightening limit position, and a position corresponding to the thread slackening limit position of the loop tightening member. The respective loci of the recess for engaging the needle thread of the loop tightening member, and the thread catch of the movable member overlap each other. The movable member is normally resiliently biased toward the stopping position by the substantially constant resilience of a resilient part thereof or by means of a separate resilient member, so that a predetermined length of the needle thread is secured during the threading operation irrespective of the stopping position of the loop tightening member, and the thread loop can be smoothly released from the loop-seizing member.