Stoffehlernachweisgeraet fuer Fehlerbrueche in Strickstoffen

1,077,330. Photo-electric flaw detection in fabrics. APPALACHIAN ELECTRONIC INSTRUMENTS Inc. July 21, 1965 [Dec.11, 1964], No.31117/65. Heading G1A. Runs and holes in a knotted fabric are detected by arranging a lamp and photo-resistor on one side of the fabric and a strip of retro-reflective material on the other, such a material on receiving light through a hole in the fabric reflects it back along the incident path to be received by the photoresistor. Fig. 2 shows a scanning head containing the lamp 46, photo-resistor 43 and a half-silvered mirror 37 which transmits light on to the fabric but deflects light returning from the retro-reflective material on to the photo-resistor. The head is suspended by legs 11 and is moved back and forth across the width of a moving strip of fabric; a cylindrical lens 31 produces a line image in the direction of movement of the fabric. In another arrangement Fig. 5 (not shown), several stationary heads are positioned spaced across the width of the fabric and have cylindrical lenses arranged to produce line images which are in a direction perpendicular to the fabric movement and whose ends overlap one another. In the case of circular knotting machines producing a tubular knot fabric, which is rotated after leaving the needles as well as moving axially, a stationary scanning head may be positioned inside the tube Fig. 8 (not shown), or outside Fig. 6 (not shown). After the tube has been flattened to form a double sheet a series of stationary scanning heads may be placed on both sides of the sheet with retro-reflective material between the two fabric layers Fig.13 (not shown). For all arrangements the electrical circuitry Fig. 7 (not shown), will only produce an output to shut down the knotting machine of the signal from any photo-resistor is above a predetermined level.