JPS57184958A - Roll mark detecting device - Google Patents

Abstract

PURPOSE:To make it possible to perform accurate detection by taking out the defect signals of the surface of a material to be checked including roll marks by using a ring adder, comparing the signals with a reference level, and judging the presence or absence of the roll mark. CONSTITUTION:The detected defect signals are obtained by optically scanning the surface of the material to be inspected in the width direction. The roll marks caused by the flaws of rolls which feed the material to be inspected are detected from said defect signals. In this case, a ring adder 10, which includes adders 11a and 11b having a plurality of input and output terminals and a shift registers 13-1- 13-8 which are connected to the input and output terminals of the adders and have a specified number of bits, is provided. The output signal (a) is compared with a comparing level (d) by a comparator 20. When the signal (a) is larger, it is judged that the roll signal is present, and a signal (r) is outputted. Therefore, even when the roll mark signal cannot be detected due to the slipping of the rolls, disturbance, and the like, the ring addition is performed, and the positive detection can be performed.