| 摘要 |
<p>PROBLEM TO BE SOLVED: To surely detect a pattern-like scab defect having no projecting and recessed parts by detecting a mirror reflection component, a mirror diffusion reflection component contained in regular reflection light and a mirror diffusion reflection component from the other directions than the regular reflection direction from the surface to be inspected. SOLUTION: Light 23 emitted from each position of a linear diffusion light source 22 is applied at an incidence angle of 60 or the like to the total width of a running steel plate 21 through a cylindrical lens 24 and a polarizing plate 25. The reflected light from the steel plate 21 enters photo detecting cameras 27a, 27b arranged in the direction of 60' to the direction of normal line of the steel plate 21. The diffusion reflected light in the direction of 25 deg. enters a photo detecting camera 28 arranged in the direction of the photo detecting angle of 25 deg. to the direction of the normal line of the steel plate 21. The light intensity of every pixel for one line in the cross direction of the steel plate 21 in the reflected light 26 and the diffusion reflected light detected by the photo detecting cameras 27a, 27b, 28 is converted to light intensity signals (a)-(c). The signals are transmitted to a signal processing part 40 and averaged to output signals for one line. An oversight can be prevented by using the average value.</p> |
