| 摘要 |
PURPOSE:To detect the residual amount and used amount of a tape, by detecting the number of revolutions of a tape reel and generating an output signal in response to a tape run speed in a tape recorder. CONSTITUTION:A magnetic tape 1 is wound from a supply reel 2 to a winding reel 3 through the front of a recording/reproducing magnetic head H. A rotation detecting means 7 is provided to obtain an output signal with a level corresponding to the number of revolutions Ps of the reel 2. The output number of revolutions Ps is squared at a multiplication circuit 32 and applied to a dividing circuit 34. On the other hand, a signal with a constant A inversely proportional to the square of a running speed of the tape 1 is outputted from a reference signal generating circuit 33 and given to the circuit 34, and a A/Ps<2> is obtained at the output, and a signal corresponding to an operated tape residual time ts is displayed on a display means 21. |
