ZIGZAG DETECTING DEVICE

PURPOSE:To detect the generation of a defective securely and automatically by detecting the lateral movement of a sheet material perpendicular to the feeding direction from the output image signal of an image pickup means and judging whether the sheet material zigzags. CONSTITUTION:A line sensor camera 21 outputs the image signal of a photographed eye mark 24 and it is judged whether or not there is the mark 24 at a correct position. Then when a film 22 zigzags and the eye mark 24 is not at the correct position, a position decision circuit 37 outputs an H-level output signal until it is judged that the mark 24 is at the correct position. Then while a flip-flop 33 outputs an H-level signal, a NAND circuit 34 outputs an L-level zigzag detection signal. The generation of a defective can be detected automatically from the zigzag detection signal.