| 摘要 |
PROBLEM TO BE SOLVED: To execute measurement on a prescribed measuring region with high accuracy insusceptible of a defective position. SOLUTION: An edge section of a laver is determined at a time when the number of dark signals involved in an image signal outputted from an image sensor is counted by an edge section determining means (step 1) and the counted value becomes a value of edge section determining information W or more (step 2). As a result, even in the case where the laver has a cutout-shaped defect, a position of the edge section of the laver is surely detected when a portion except the defect blocks a scanning line. Therefore, a starting position of a measuring region which has been changed heretofore is not changed by the position of the defect so that it is possible to obtain the accurate measurement result in terms of the prescribed measuring region. |
