Inspecting the Back of Woven Carpets for Pattern Distortion

Abstract

Any distortion seen in the pattern repeat of woven Axminster carpets causes considerable problems for both manufacturer and end-user. Instrumental 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 nature and severity of any pattern distortion, on-line and in real time. This paper discusses two alternative methods for performing the measurement. The first, using a CCD line-scan camera and conventional digital-image-processing techniques, has been investigated fairly thoroughly and shown to be effective but is rather expensive. Evaluation of the other remains to he completed; it uses a well-spaced array of point sensors and promises to be equally effective hut much less expensive. The paper also considers how the results of the instrumental measurements should be presented to the end-user.