Abstract: An edge detector for detecting the edge of fabric in a textile folding or guiding device for an industrial sewing machine. The detector includes a light source mounted adjacent to one surface of the fabric as the fabric enters the folder. The light source is positioned for directing light onto the surface of the fabric. A photodetector is located adjacent to the light source for receiving light reflected from the surface of the fabric. The photodetector provides an output signal in response to the light reflected from the surface of the fabric which is indicative of the position of the fabric in the folder.