| 摘要 |
PURPOSE:To detect the terminal of a microfilm securely through simple constitution, by providing sensors for mark detection in front of and behind a retrieval part in a film running path, and processing their outputs. CONSTITUTION:The microfilm 11 unwound from a letoff reel 10 is wound around a take-up reel 12 through the running path. In the running path for the microfilm 11, a retrieving device 20 is arranged. Further, the sensors 13 and 14 for mark detection are provided in front and rear of the retrieving device 20. The detection signal of the upstream-side sensor 13 in the running direction of the microfilm 11 is summed up by a counter 17 and the detection signal of the other downstream-side sensor 14 is substracted from the sum. When the counted value of the counter 17 decreases to zero, it is judged that the terminal of the film 11 comes. |
