| 摘要 |
<p>PURPOSE:To run a tape at a fixed high speed by traversing a head on a recorded track during a high speed running and detecting the number of tracks to be scanned to control a reel drive motor. CONSTITUTION:Heads 2a, 2b attached to a rotating cylinder 1 at a winding angle of 90 deg. scan tracks 21, 22 on a running tape 3. A gap of the two heads has azimuth angles of + and - with respect to a direction 20 and a track width of the head is about 1.5 times as wide as the track width on the tape. When the head of the azimuth angle of the + side scans as shown by broken lines 23, only a bias line part is reproduced, for instance the track 22 is not reproduced and in an envelope of a reproducing signal, crests and roots are produced. This signal is detected 6, the envelope is extracted, passed through a BPF7, a waveform is shaped 8, an AND gate 9 is opened, only a central part of the signal after shaped is taken out, a pulse is counted 10 every interval of 90 deg., and a value proportional to the number of the tracks traversed by the head. Since this value is proportional to the tape speed, a tape running speed is understood and based on this value, the speed control is carried out.</p> |
