| 摘要 |
PURPOSE:To accurately discriminate the end part of a black long-sized sheet by forming the surface of a roller for supplying the sheet continuously roughly in white, and irradiating the long-sized sheet surface and roller surface with light and comparing their quantities of reflected light with each other. CONSTITUTION:The long-sized sheet 2 is arranged on the roller 1 and conveyed as shown by an arrow by the rotation of the roller 1. Then a light source 4 above the roller 1 projects the light on the sheet surface 2 and roller 1 and a line camera 5 detects their reflected light. The angle theta between the liquid source 4 and line camera 5, and roller surface 1 and sheet surface 2 is set to about 45 deg.. Here, the roller surface 1 is formed roughly in white, so diffuse reflection is accelerated and the quantity of reflected light is large; even if the surface is dirty, the quantity P of reflected light at a 45 deg. irradiation angle does not vary large. The surface of the sheet surface 2 is nearly black and its quantity S of reflected light is smaller than the quantity P of light. For the purpose, the quantities P and S of reflected light are compared with each other to discriminate the sheet end part distinctively.
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