FIELD: measurement technology. SUBSTANCE: light emitted by laser and reflected from cloth is directed perpendicular to cloth and is detected by photodetectors from two directions or two inclined light beams are directed on to moving cloth from opposite directions and beams reflected perpendicularly to cloth are detected or light beam is directed on to moving cloth and firstly first reflected beam is detected at first angle, then second reflected beam is detected at second angle. Electric measurement signal from photodetectors is compared in electron signal processor with reference signal stored in it and which is representation of calibration bending line. Bending line is determined by maximum of correlation signal which presents result of computation for establishment of correspondence between measurement and reference signals. EFFECT: simplified process of detection of bending line on packing cloth. 20 cl, 14 dwg
