| 摘要 |
A magnetic tape transport system with a magnetic tape cassette is provided with a tape transport measuring device which comprises a rotary pulse device which cooperates with a light source and a light-sensitive cell, the pulse device being rotated during transport of the magnetic tape and the number of pulses detected by the photo-cell being counted and displayed with the aid of a read-out device, such as a digital display device. In order to obtain a correct linear relationship between the length of tape which has been transported and the number of counted pulses, a tape guide roller in the cassette is used as pulse device, the cassette housing locally being provided with a light-transmitting portion, such as openings or transparent portions.
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