| 摘要 |
PURPOSE:To prevent the generation of defectively closed cans by providing a light projecting device, which can project projection lights simultaneously along the overall circumference of a flange part, and a light receiving device which is arranged near the light projector and has a photoelectric transducer. CONSTITUTION:Light projectors 13 are so constituted adjacently to one another that projection lights 14 are made incident along the overall circumference on the upper face of a flange part 4. A light receiving device 12 is provided with many photodetectors 15 which are adjacent to one another into a form of a ring, and each photodetector 15 is placed near the part above the flange part 4 on the inside of the corresponding light projector 13. The degree of bending of the flange part is discriminated on a basis of the number of output indicators 19 which are turned on. By this constitution, the flange bending part is detected in a very short time, and the generation of defectively closed cans is prevented. |
