DEFECT DETECTION OF UNWOVEN FABRIC

摘要

PURPOSE:To detect uneven texture of an unwoven fabric and stains or the like scattered thereon with a high S/N ratio, by a method wherein an illumination light transmitted through the fabric is reflected with a reflector of the gray gradation almost the same as that of the fabric and transmitted therethrough gain to be received. CONSTITUTION:When a lighting device 9 is lighted to light the surface of an running unwoven fabric 2, a part of the light is reflected on the surface of the unwoven fabric 2. The light transmitting property of the fabric 2 allow a part of the illumination light to reach a reflecting body 11, where it is reflected and transmitted through the unwoven fabric 2 again from the back side to the surface side. a detector 10 receives both of the reflection light (A) and the transmission reflection light (C). But since the reflecting body 11 has the gray gradation almost the same as that of the unwoven fabric 2, apparently uneven texture of the unwoven fabric 2 vanishes as viewed from the detector 10 to uniform the density of the texture thereby enabling detection of a defect with a high S/N ratio.