| 摘要 |
<p>PURPOSE:To keep the speed of a magnetic tape constant and to attain high speed feeding by applying drive control to a drive motor of a winding reel base based on a detection output of a winding diameter detection circuit for a magnetic tape roll at the high speed fast forward reproduction mode. CONSTITUTION:Number of revolutions of supply and winding reel bases is detected respectively by frequency generators 18, 19 and its output signal is inputted to a winding diameter detection circuit 20. The circuit 20 obtains a ratio of number of revolutions of each reel to obtain a radius of the winding tape roll. The output of the circuit 20 is given to a speed reference voltage generating circuit 21 to generate a speed reference voltage corresponding to the winding diameter detection value. Moreover, the output of the generator 19 is compared with the reference voltage at a speed comparator circuit 23 to obtain an error signal of a speed system. An output reproduced by a control head 8 is inputted to a phase control circuit 10 to receives an error signal of a phase system. Both error signals are inputted to a mixer circuit 12, from which a mixer signal is inputted to a motor drive circuit 13 which controls a drive motor 17 thereby controlling the carrier speed of a tape 3 to be a control value.</p> |
