Detection of broken filaments

An improvement in a process for melt-spinning a synthetic polymer into a multiplicity of filaments, comprising extruding the molten polymer through spinning capillaries into filamentary streams, quenching said filamentary streams with cooling air to harden the streams into filaments, and applying finish to said filaments, and wherein the improvement comprises the capability to sense and record the presence of a filament defect by passing said filaments past a flexible cantilever beam that is spaced from said filaments at a predetermined distance from said filaments, and wherein a piezoelectric film sensor is secured to said beam, and wherein said film sensor is part of an electric circuit containing also means for recording electric impulses from said film sensor, whereby impact from a filament defect on said beam will cause said beam to flex and stretch said film sensor, and will initiate an electric impulse from the film sensor in said electric circuit, and wherein said electric impulse is recorded.