Patent US 3,932,042

Apparatus for and method of inspecting transparent containers of the type used for food and beverages for the presence of dirt, foreign objects and manufacturing defects, such as birdswings. The apparatus includes illuminating each container from different angles and in a sequential order, and processing the illuminated images by photo-electronic scanning apparatus to obtain a response on a change in the illumination level within an electronic window of an amount sufficient to actuate a container reject mechanism.