INSPECTING THE BACK OF WOVEN CARPETS FOR PATTERN DISTORTION

Any distortion seen in the pattern repeat of woven Axminster carpets c auses considerable problems for both manufacturer and end-user. Instru mental measurement of the straightness of the weft threads on the back of a woven carpet can be used to provide a direct indication of the n ature and severity of any pattern distortion, on-line and in real time . This paper discusses two alternative methods for performing the meas urement. The first, using a CCD line-scan camera and conventional digi tal-image-processing techniques, has been investigated fairly thorough ly and shown to be effective but is rather expensive. Evaluation of th e other remains to be completed; it uses a well-spaced array of point sensors and promises to be equally effective but much less expensive. The paper also considers how the results of the instrumental measureme nts should be presented to the end-user.