| 摘要 |
<p>PURPOSE:To shorten an FF and an REW time by detecting a take-up state optically and switching a tape feed at a six-fold speed from the beginning to the middle and at a four-fold speed from the middle to the end. CONSTITUTION:Photocouplers 12 and 13 each output four pulses by reflecting plates 10 and 11 on every rotation of reel drive disks 7 and 9 to generate pulses at cycles corresponding to the radii of the reels. The pulses of the photocouplers 12 and 13 are impressed to a frequency-voltage converter 14. Their outputs Vt and Vs are impressed to a voltage comparator 15. When a cassette with a small take-up reel tape radius is put in the FF (fast-forward take-up) operation, the output Vt is constant and a feed reel rotates slow in the beginning and fast in the ending, so the conversion output Vs is high in the beginning and low in the ending and an output Vc1 is an inverted output in the middle. When a cassette having a small feed reel tape radius is placed in the RED (fast rewinding) operation, an output Vc2 is an output having the opposite polarity to the Vc1. Therefore, the comparison output Vc2 in the REW operation is polarity-inverted by an inverter 16 and an output Vc0 selected by a switch 17 according to modes sends a speed change command to a speed control part 18 to control a motor 1.</p> |
