Abstract: An apparatus for visual inspection detects defects on an object to be inspected, stores the defects, calculates the distance between two detected defects from the positions of the two detected defects, and judges the two detected defects to be different portions of a single actual defect when the distance between the two defects is less than a predetermined threshold value. The apparatus also stores the actual defects, as well as class-of-actual-defect inference rules necessary for inferring the class of the actual defects from the class of each detected defect. The class of the actual defect is judged from the class of each detected defect on the basis of the class-of-actual-defect inference rules, and the class of the actual defect is then stored. A method of visual inspection and a method of removing the cause of an abnormality are also disclosed.

Abstract: Two X-ray transmission images of an object, e.g. an electronic device package structure having plural soldering layers are detected in two directions inclined to the plural layers, on the basis of a relative position relation between both X-ray transmission images, one X-ray transmission image is converted on the assumption that soldering portions to be detected are located at a certain layer, into the image in the direction in which the other X-ray transmission image has been detected, and the converted X-ray transmission image is with the other X-ray transmission image to decide that the soldering portions at coincided positions are located at the layer at issue.