| 摘要 |
PURPOSE:To discriminate marks securely, by arranging the 1st-the 4th mark sensors along a film conveyance path at specific intervals. CONSTITUTION:A light source 10 for projection is arranged over the conveyance path for a microfilm 1 and optical fibers 11, 21, 31, and 41 for mark detection are arranged under the conveyance path in the running direction of the marks of the film 1. In this case, the optical fibers 11, 21, 31, and 41 are so provided to satisfy the relation that a<x<b<y<c<z, where (c), (a), and (b) are intervals between the optical fibers 11 and 41, 21 and 31, and 11 and 31, and (x), (y), and (z) are the length of a slip mark, the length of a file mark, and the length of a block mark. Light photodetected by the optical fibers 11, 21, 31, and 41 is converted by sensors 12, 22, 32, and 42 into electric signals, which are inputted to a signal processing circuit 50 through amplifiers 13, 23, 33, and 43, and waveform shaping circuits 14, 24, 34, and 44. |
