| 摘要 |
PURPOSE:To make it possible to measure the amount of the turning up of the edge of the plate, by providing a reference light source in the common light receiving range, and utilizing the geometrical relationship of a triangle formed by two optical detectors and the edge of the plate material and a triangle formed by the edge of the plate material and the difference between the light receiving ranges of the two optical detectors from the reference light source. CONSTITUTION:The two optical detectors 32 and 33 are provided with a specified distance being provided in the advancing direction of the plate so that the light receiving ranges are overlapped. The amount of the turning up of the edge of the plate material 31 is measured, based on the geometrical relationship of the triangle formed by said two optical detectors 32 and 33 and the edge of the plate material 31, and the triangle formed by the edge of the plate material 31 and the difference between the light receiving ranges of the two optical detectors 32 and 33 from the reference light source 34. |
