| 摘要 |
<p>PURPOSE:To momentarily perform the changeover to a playback speed at the same speed as the recording accurately, by latching a rotational frequency switching control signal via a retrigger type multivibrator and D type FF and the like according to a playback reference signal, in a recording and playback device. CONSTITUTION:If a playback speed is a half the recording speed, the frequency of a playback reference signal is halved, the output of one retrigger type monostable multivibrator M2 is at a low level and the output terminal of one D type FFD2 is at a low level every time when the playback reference signal is applied. A latching circuit 2 is set with this fall signal to produce a high level output. A transistor Q1 of rotational frequency switching circuit 3 is conductive to change the time constant and switching is made so that the rotational frequency of capstan is the same speed as that at recording. Further, in this state, the playback speed can automatically be switched momentarily and accurately so that the latching state of the circuit 2 is not changed and the same speed as the recording speed can be obtained without reswitching, even if the output of the FFD2 is surely inverted into a high level immediately after the switching of playback speed.</p> |
