Yarn fault detection for tufting machines

摘要

A controlled needle tufting machine has a cyclically reciprocating latch bar to which the needles may be selectively latched in accordance with a pattern to reciprocate and insert loops of yarn into a backing material or to not be latched and remain stationary above the backing material includes yarn detection apparatus for determining whether the feeding of yarn for the needle is correct. The detection apparatus includes a yarn fault detector for detecting whether yarn is moving between a source and a respective needle and for providing a signal in response to such movement. The yarn movement signal is compared with a signal from the pattern control and if the needle is latched and yarn is supposed to be moving, a fault signal is provided if the yarn is not moving. If the needle is supposed to be stationary but the detector indicates that yarn is moving, a fault signal may also be provided. In either case the fault signal is displayed and the machine may be stopped. An optical detector is disclosed for detecting yarn moving through a bore in a body member within which the optical detector is mounted.