Abstract
In the manufacturing industry, it is common to conduct visual inspections in order to ensure the quality of products' external appearance. The inspection work, which involves thoroughly checking products, is very tiring and straining on the eyes. One of the reasons for this eye strain is that under the current inspection methods, inspectors are required to use their "central visual acuity" to focus on each inspection item. Previous studies have presented alternative inspection methods which allow inspectors to use their "peripheral visual acuity," which allows more sensitive detection of contrast, and thus may lead to less defects missed and less fatigue. However, the proposed methods fail to consider the size or visibility of each defective item, and the procedures for establishing inspection methods are not specified. This study thus aims to achieve the following three objectives. 1) Experimentally examine the broadening of effective visual field in proportion to the contrast ratios of products and defective items. We define effective visual field as the visual field identified with peripheral visual acuity. 2) Explain the inspection method, which uses the effective visual field concept, and describe the procedures for establishing the inspection method. 3) Present a case in which the established inspection method was applied to an actual business and verify the effectiveness of the method.
