| 摘要 |
PURPOSE:To constantly display the correct quantity of a magnetic tape by discriminating the combination of a recording speed and the hub diameter of a reel at the time of recording the magnetic tape, obtaining the circumference length of the tape wound on both the reels from the discriminated recording speed and the counted value of a counted travelling control signal, and arithmetic-operating the quantity of the tape wound on both the reels. CONSTITUTION:A travelling control signal detection means 4 is provided, at the time of a fast forwarding and a rewinding, the travelling control signals on the magnetic tape moving during one rotation of a feed side and a take-up side reels 2, 3 are respectively counted, the combination of the recording speed and the hub diameter of the reel at the time of recording the magnetic tape is discriminated by the arithmetic, the circumference length of the tape wound on both the reels is obtained from the discriminated recording speed, the counted value of the counted travelling control signals and the quantity of the tape wound on both the reels is obtained by the arithmetic from the circumference length and the discriminated hub diameter. Thereby, the correct quantity of the magnetic tape can be constantly displayed only under the fast forwarding and the rewinding states without bringing a magnetic recorder to a recording and reproducing state simply and with low cost by a quantity of tape display device.
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