| 摘要 |
PURPOSE:To surely decide an existence of a defect without an effect of a screw part by extracting a projected pattern in the manner of projecting a picture on an axis in the circumferential direction after the picture signal for an entire circumference of the imaged screw part is differentiated to the circumferential direction and binarized. CONSTITUTION:An original picture for the entire circumference of the screw part on a container is made in such a manner that the container 1 is imaged with an image picking-up device 4 consisting of a condensing lens 4a and an image pick-up element 4b by rotating the container to the circumferential direction of the screw part on the container, and this original picture is differentiated to the circumferential direction of the screw part on the container. A signal for the screw thread is comparatively small, and the signals for the end part and the defective part of the screw are comparatively large. To remove the signal for the screw thread, the differentiated picture is binarized with an appropriate threshold, thereby the picture displaying the signals only for the end part and the defective part of the screw is obtained. Next, the signal values for each picture element of the differential binarized picture obtained are projected to a center axis direction of the screw part on the container. Then, the existence of the defect, i.e. normal/defective for the screw part on the container is decided by comparing distinctive features between the obtained projecting pattern and the projecting pattern for the end part of the screw which is given in advance. |
