| 摘要 |
<p>PURPOSE:To make equal a tension of a tape of a magnetic head section in both running directions and to prevent an increase of a wear in the magnetic head by setting a back tension applying voltage during a reverse running to a lower value than during a forward running. CONSTITUTION:During a reverse running, a transistor (Tr) 23 is controlled to be turned on and Tr 24 to be turned off. A motor driving voltage of a line 22 is impressed to a reel motor 7, a back tension voltage controlled by a circuit comprising a diode 39, a Tr 40 and a resistance 41 is impressed to a reel motor 8, respectively. In a terminal 25 during the reverse running, a Tr 29 is maintained to be turned off at L. Even when the same motor driving voltage as during a forward running is supplied to a line 22, an input terminal voltage of a differential amplifier 31 becomes higher, and an output voltage is lowered and an impedance of the Tr 40 is lower than during the forward running. Even when the back tension applying voltage is lowered during the reverse running, a speed detecting roller enhances a tape tension in a magnetic head section to make equal the tape tension of the head section during the reverse running to during the forward running.</p> |
