Dent method of detection of sheet condition ones and dent detection device null of sheet condition

摘要

PROBLEM TO BE SOLVED: To accurately detect only the recess of a sheet-like article having a flow pattern such as artificial marble without altering the disposition, measuring conditions of an inspecting apparatus one by one even if the article is vibrated in horizontal or upward or downward (vertical) direction during inspection. ;SOLUTION: The sheet-like article to be fed in upward and downward moving range L is illuminated by the line-like illuminating unit 3 of an incident angle (45≤α≤70°) and an illumination width W (W≥L sin 2α/cos α). The regularly reflected light is received by a line sensor 4, and hence even if the inspection surface is moved upward or downward, a stable shade is formed at the recess to obtain an output having clear change. The output signal is differentiated to accurately detect only the recess, the differentiated signal is binarized, subjected to a run length coding, and then connectively processed while expanding it with a predetermined value, thereby accurately discriminating the edge or recess separated from the image.;COPYRIGHT: (C)1997,JPO