| 摘要 |
PURPOSE:To improve remarkably click recorded at the start of sound recording and to eliminate the erasure at overlapped sound recording, by detecting a position where a tape and a head contact actually and the tape starts running and using its output so as to start and control the supply of a bias current. CONSTITUTION:When a sound recording command comes at a time tg, the tape starts running by a pressing force of a pinch roll and a capstan and a torque as shown in B in the figure after a time t1 elapsed. Further, a reel motor starts rotating, a pulley 10 (eccentric cam 11 and the 2nd cam 12) is driven in the arrow direction, a lever 14 is driven with the eccentric cam 11 and a head base 20 is shifted. A lever 13 is turned by the 2nd cam 12 at a time t0 after the time tg and a detecting switch 16 is turned on. The on-state continues until the time t1, the tip of the lever 13 falls down onto a recess 12e at the time t1 and the detecting switch 16 is turned off. That is, a signal turning from on to off at the time t1 is obtained, a bias oscillating circuit is operated by using this signal so as to rise the bias current. |
