| 摘要 |
PURPOSE: To exactly decide the presence or absence of the crack in a work and to improve inspection accuracy by extracting the picture element having lower luminance than base luminance from the picture elements composing an inspection surface image and deciding the presence of the crack when the continuous number is a prescribed value or more. CONSTITUTION: A nondefective picture element having higher luminance than lower limit luminance is tracked up to a tracking termination point E, comparing the luminance of the picture elements around tracking reference lines L1 to L4 with the lower limit luminance. When a ring varistor to be an inspection object is a nondefective product which has no crack, the tracking of the nondefective picture element is continued from a starting point K to the termination point E along each of the tracking reference lines L1 to L4. As a result, the decision of the absence of the crack is performed. When the ring varistor is the defective product having a crack 1a or when the picture element which does not satisfy the lower limit luminance crosses and exists in the part of an annular part, the tracking of the nondefective picture element in the tracking reference line L 4 is largely deviated from the line L4, the tracking of the nondefective picture element can not be continued up to the termination point E. Thus, the decision of the presence of the crack is performed. |
