| 摘要 |
<p>PURPOSE:To simplify speed control of rotating drum, by constituting the rotating speed control loop through the use of a pulse generator provided to form the rotating phase control loop of a playback device. CONSTITUTION:A magnetic tape 3 is wound on a rotating drum 1 having a pair of rotating magnetic heads 2a, 2b, and while turning the drum 1, a pulse generator 6 consisting of the head 6a and the magnet 6b built in the drum 1 is contacted. Next, the pulse generated at the generator 6 is fed to a smaple hold circuit 13 via an amplifier 7 and a wave shape circuit 8, and the vertical synchronizing signal from the input terminal 10 is fed to the circuit 13. After that, the output of the circuit 13 is fed to a drive circuit through an addition circuit 17 to control a drum driving motor 4. Next, added with a rotating phase control loop 5 thus constituted, a rotating speed control loop 20 consisting of a peack hold circuit 21 and a smaple hold circuit 22 is provided, and the said addition circuit 17 is controlled through the output of the circuits 7 and 8 via an addition circuit 24.</p> |
