| 摘要 |
PURPOSE:To accurately display the operationable time of the remaining tape capable of recording by inputting to an arithmetic part the output of the first or second rotational angle detecting part at the time of tape-unloading after drawing the magnetic tape by operating the operational button to be on and removing the slackening. CONSTITUTION:A cassette casing 1 is loaded in the magnetic video recording and reproducing device and the operation button 34 is turned on, and then the magnetic tape 14 is drawn from the feeding reel 3 side by a controlling part 25. After removing the slackening of the tape against the reel 3 and a winding reel 5, the tape is wound around the reel 3 and is unloaded. During said rotation, the number of slits in a disc 20 that rotates with the reel 3 is counted by a counter 29a and inputted to the arithmetic part 31, so that the diameter of hubs 2 and 4 is discriminated by a discriminating part 32. Only when the discrimination is not executed, the reels 3 and 5 are made rotate to rewind or for rapid traverse of the tape. During this rotation, the number of slits in a disc 21 that rotates with the reel 5 is counted by a counter 29b, and inputted to the arithmetic part 31. In such a manner as the above, the tape's remaining operatable time able to be recorded is calculated accurately, and is displayed in a display part 33.
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