Device for the automatic detection and inspection of defects on a running web, such as a textile fabric

摘要

The device includes a motor that move the web and an electronic camera which supplies a signal representing an image of the web formed on an image sensor having photosensitive points. The device has synchronization of the duration of a predetermined number of successive pitches of the web passing through the optical field of the camera and the duration separating the start of two successive imaging operations of the camera. Thus, an optical filtering is performed. From one image to the next, the same photosensitive point of the sensor corresponds to identical portions of threads and interstices of the web, so that any optical variation of the threads or interstice is detected. The signals representing the images produced by each photosensitive point during successive shots correspond to zones of material with similar designs. If there is no difference in the material between two successive zones observed in this manner, and in particular if there is no defect, the representative signals corresponding to these zones are exactly identical. The processing of the signal is therefore simplified and makes it possible to detect defects of very small size and/or very little different from the normal pattern.