| 摘要 |
<p>PURPOSE:To prevent malfunction by detecting a fixed non-signal interval by making sure that a zero output interval of a magnetic head when a tape change in run direction is shorter than the time when no signal passes. CONSTITUTION:Now, a magnetic tape runs in a quick traverse mode and a non- signal interval starts. When the non-signal interval continues for a fixed time, non- signal interval detecting method 6 reaches an inversion level and its output becomes ''H''; and NAND gate circuit 8 generates a string of pulses, which are counted by counting method 10 and applied to input terminal A of comparing method 13. Content B of memory method 12 is initially zero, comparing method 13 generates an A>B output and the output of NOR gate 14 becomes ''H'', so that counting method 24 will count up by one. On the other hand, monostable multivibrator 16 generates a single pulse to make the output of NAND gate 17 ''L'' and a REW command 20 is sent. Next, when the magnetic tape having slightly overrun stops and the non-siganl interval restart by reversing, NAND gate 18 sends a FF command 22 and counting method 24 counts up by one, so that its contents reach a fixed value, a PLAY command 26 will be generated.</p> |
