| 摘要 |
<p>PURPOSE:To secure the detection of the tape roll-in by giving the comparison between the value obtained by converting the rotational frequency of the reel turntable into the electric signal and the value obtained by making the converted value mentioned above pass through the LPF, thus realizing the simple and low-cost manufacture along with the miniaturization. CONSTITUTION:The output of D/A converter 6 is equal to that of LPF7 when the tape is running under the steady condition, and thus no output is caused from comparator 8. In case the tape is rolled in, take-up reel turntable 2 stops its rotation at the beginning of the tape roll-in and then starts the backward rotation. The small diameter of the capstan increases immediately with start of the roll-in of the tape, and accordingly the substantial running speed of the tape increases. As a result, the rotational frequencies of take-up reel turntables 1 and 2 increase, and the value larger than the steady running time of the sum proportional to the rotational frequencies of turntables 1 and 2 is supplied to one input end of comparator 8. While the output of LPF7, i.e., the value before roll-in of the tape is supplied to the other input end, and this value is smaller than the value of converter 6. As a result, comparator 8 generates the output to discontinue the operation of the mechanism.</p> |
