| 摘要 |
PURPOSE:To minimize influences of disturbance by a mechanism wherein a shield plate driven to be swung by virtue of weight of a semiconductor substrate is disposed between a light source and a photodetector, so that an optical path is opened and closed by the swing motion of this shield plate to detect the presence or absence of the semiconductor substrate. CONSTITUTION:The mechanism comprises a light source 1, a photodetector 2, a shield plate 3 which interrupts an optical path between the light source 1 and the detector 2 and which is easily driven to be swung by virtue of weight of a wafer, and a rotary shaft 4 for the shield plate 3. An integrated photointerrupter is used as the light source 1 and the photodetector 2. The optical path between the light source 1 and the photodetector 2 is normally interrupted by the shield plate 3. When a wafer 6 is placed on a base 5 of this detection mechanism or passes over the base 5, the shield plate 3 is driven to be swung by virtue of weight of the wafer 6 in the clockwise direction (as indicated by arrows in the figure), thereby to open the optical path. |
