| 摘要 |
<p>PURPOSE:To detect a magnetic tape in length during its loading to a rotary drum by detecting a rotating speed of a reel at the loading time and calculating the tape length based on the rotating speed. CONSTITUTION:A revolution detecting plate is fitted to each driving motor of a supply reel 1 and a take-up reel 2, and a frequency generator for detecting these revolutions is provided on a main chassis. Rotating speeds of the supply reel 1 and the take-up reel 2 are detected via the above revolution detecting plates and the frequency generator by reel rotating speed detecting means 7 and 8. Then, the length of the magnetic tape 3 wound around the supply reel 1 and the take-up reel 2 is calculated from a prescribed calculating express by a tape length calculating means 10 based on the detected rotating speeds by the reel rotating speed detecting means 7 and 8 at the loading time. Consequently, a tape residual amt. can be displayed immediately after the loading, and also fast forwarding and rewinding are feasible at optimum speed.</p> |
