| 摘要 |
PURPOSE:To detect even a body which passes through any part of a cylindrical tube securely by a body passage detector in the tube, by arranging light emitting elements and photodetecting elements on the internal wall of the tube by turns so that they face to each other. CONSTITUTION:On the circumferential wall of a tube 1, a light emitting element A1 and a photodetecting element A1' are arranged, and a light emitting element A2 and a photodetecting elements A2' are also arranged next to the photodetecting element A1' and light emitting element A1 respectively. Then, center lines of light beams emitted from the light emitting elements A1 and A2 are in parallel across the center point O of the tube 1. Several couples of light emitting elements and photodetecting elements are arranged similarly on the circumferential wall of the tube 1. When a work 2 passes near the circumferential wall of the tube 1, the light beam from the element A1 decreases in quantity because it is cut off partially, so the element A1' detects the passage of the work 2 securely. Since each photodetecting element receives light from only its corresponding light emitting element, the passage of a work is detected securely. |
