【発明の名称】表面欠陥検査装置

Japanese Patent JP2955686

B2

PURPOSE:To enhance precision of defect detection by deciding whether the level of a differential video signal corresponding to a surface detect is larger than a first threshold at a specified level and smaller than a second threshold, thereby detecting the position of a surface defect. CONSTITUTION:In the case when a defect 12 is a protrusion, for example, light from a position 16, where light intensity is high, on an emitting surface 13a of a light source 13 impinges on the surface 12a of a defect 12 opposed to the emitting surface 13a, so that the direction of specular reflection changes, and part of the reflected light thus enters a video camera 14. However, only light from a position 17, where light intensity is relatively low, on the emitting surface 13a impinges on the surface 12b of the rear side of the defect 12, so that the reflected light from the surface 12b on the rear side of the defect 12 scarcely enters the camera 14. The camera 14 outputs a video signal varying with variation of lightness on a light-reception image 15 and the signal then enters a video signal decision section 18. In the decision section 18, first and second threshold values are set. Portions other than the defect 12 are thus discarded as small level variation by means of the first threshold value, and the portion within the region of the defect 12 is discarded as large level variation by means of the second threshold value thereby detecting presence of a surface defect including its position.

TANAKA KAZUMOTO
SUGIHARA TAKESHI
MAKIMAE TATSUMI

JP33956790A

October 04, 1999

November 30, 1990

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MATSUDA KK

B23Q17/24; G01N21/88; G06T1/00; G06T7/00; H04N7/18; G01B11/30; (IPC1-7): G01N21/88; G01B11/30; G06T7/00; H04N7/18

JP6080744A
JP6331360U

Yasuo Mihara

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