| 摘要 |
PROBLEM TO BE SOLVED: To enable the overlap of thin film members such as thin and semitransparent film tapes to be stably detected, by a method wherein a light projecting means and a photodetective means are each provided confronting the front and rear surface of the thin film member, and light volume data detected by the photodetective means are compared with reference light volume data detected by the photodetective means when a thin plate member is present. SOLUTION: A light projecting means 4 and a photodetecting means 5 are each arranged confronting each other above and below a transfer path of a pair of guide rails 2 and 3 which guide a thin plate member 1 such as a thin and semitransparent film tape. The photodetecting means 5 is connected to a comparison/decision circuit 7 through the intermediary of an A/D conversion circuit 6. The comparison/decision circuit 7 compares detected light volume data 6a outputted from the A/D conversion circuit 6 with reference light volume data 8a previously stored in a memory 8 and judges which is larger. At this point, the reference light volume data 8a are light volume data outputted from the A/D conversion circuit 6 when the thin plate member 1 is single in number. When the thin plate member 1 is single, the detected light volume data 6a are nearly equal to the reference light volume data 8a.
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