| 摘要 |
<p>PURPOSE:To reduce the damage of the breakdown, rupture, etc. of a tape and the excessive wear of a magnetic head by controlling the rotary speed of a drum by the magnetic tape tension value. CONSTITUTION:The number of revolutions of a motor 1 is detected by a detector 3, subjected to a F/V convertion 6, compared 9 with the output voltage of a reference speed equiv. voltage generation circuit 13 and the error voltage is obtd. Also, the rotary phase of the motor 1 is detected, subjected to phase comparing 4 with the reference signal of a reference phase signal generation circuit 5 and the error voltage is obtd. via a phase property compensation circuit 7 and an error amplifier 8. The respective error voltage is added 10 and the phase control of the motor 1 is executed via a switch 15. The detected 18 tension value and set 20 tension value are then compared 19 and in case of the detection value being larger the switch 15 is changed over to a side (b) and a switch 12 to a side (d) respectively, the set voltage of a low speed set circuit 22 and the output voltage of the convertor 6 are compared 11 and the error voltage is obtd. The speed of the motor 1 is controlled with this error voltage via the side (b) of the switch 15 and a driving amplifier 16.</p> |
