Abstract: The apparatus detects corduroy cutter needles coming out of the weft yarn loop channels which are being cut open by the needles, by means of a laser beam scanning about 10 to 20 times a second, transversely across the region where the parallel needles are working. The scanning laser beam creates a diffused light pattern having the general form of a transversely oriented geometric prism, e.g. a cylinder; and a plurality of detector devices determines any variation in the light distribution, as to time and lateral distance, in this scattered or diffused light pattern. A logic circuit carries out and displays the results of the scanning and detecting, and stops the corduroy cutting machine when an emerged needle is detected.

Abstract: The apparatus detects corduroy cutter needles coming out of the weft yarn loop channels which are being cut open by the needles, by means of a laser beam scanning about 10 to 20 times a second, transversely across the region where the parallel needles are working. The scanning laser beam creates a diffused light pattern having the general form of a transversely oriented geometric prism, e.g. a cylinder; and a plurality of detector devices determines any variation in the light distribution, as to time and lateral distance, in this scattered or diffused ight pattern. A logic circuit carries out and displays the results of the scanning and detecting, and stops the corduroy cutting machine when an emerged needle is detected.