| 摘要 |
PURPOSE:To automatically perform highly accurate measurement, by a method wherein a can lid is placed on a turntable and the rivet part of the can lid is illuminated from above by ring-shaped diffused light and photographed by a camera. CONSTITUTION:The rivet 6 of the can lid 2 placed on a turntable 1 is uniformly illuminated by the soft light due to the diffusion plate 5 provided to the under surface of a ring light 4. When the central upper part of the rivet 6 is photographed in this state by a video camera 3, the top surface of the rivet 6 becomes a white image and the outside part thereof becomes a black image to obtain an image having a sharp boundary part. This image is converted to a video signal and the diameter of the rivet 6 at a specific position is automatically operated by an image processor. This measured value is recorded and displayed on a monitor picture and the diameter of the rivet 6 can be read by the scale of said picture. Next, the turntable 1 is rotated by a required quantity to perform the same measurement and, even when there is an error in the rolling mesh direction of the can lid, more precise measurement can be performed.
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