| 摘要 |
<p>PURPOSE:To quickly detect a defect with high accuracy by calculating the luminance distribution of each signal based on each video signal obtained by photographing, extracting the characteristic amount of the distribution, and detecting a defect in the outer appearance such as the height of an object to be inspected based on the extracted amount. CONSTITUTION:This apparatus is provided with a controlling mean for controlling the depth of field in a plurality of stages when the depth in a direction of an optical axis of a photographing means including a part to be inspected of an object 7 is rendered a first depth of field delta1, and the depth smaller than the depth of field delta1 is another depth of field delta2, a controlling means for controlling the focal length of the photographing means in a plurality of stages f1...fn, and an extracting means 5 for extracting the characteristic amount of the luminance distribution of each signal based on each video signal when the object 7 is photographed at the depth of field delta2 for every controlled focal length f1...fn. The outer appearance of the object is inspected on the basis of the value of the extracting means. Since the most suitable characteristic amount of the object 7 can be extracted by photographing for every focal length at the depth of field delta2 which is smaller than the depth of field used to grasp the whole of the object 7, it becomes possible to inspect a defect in the height of the outer appearance of the object quickly with high accuracy.</p> |
