Significant difference method of detection null of sheet condition suffering inspection

摘要

PURPOSE:To prevent an image from affecting on the detection of a defect, by masking an image detection signal in a mask range irrelevant to the contour of the image. CONSTITUTION:Reflected light from a sheetlike material 1 to be inspected is scanned axially with a camera 5, video information obtained is taken into a contour extracting means 6 to extract the contour of an image 2 and a defect 3. An output from the extracting means 6 is written sequentially into a memory means 10 capable of simultaneously writing and reading performing an automatic updating by scrolling in synchronization with a running position information of the object 1 being inspected. Then, after a set frequency, pattern information written into the memory means 10 is read out sequentially as contour mask output to be inputted into a comparison means together with the current output to be inspected. This comparison means 12 detects pattern information differing from the subsequent frequency of pattern information read out of a binary coding circuit 13 for defects as significant difference.