| 摘要 |
<p>PURPOSE:To obtain the optimum back tension by detecting the rocking position of a tension arm, and adjusting the braking force of a supply reel base so as to be set at the rocking position conformed to the optimum back tension. CONSTITUTION:A tension servo mechanism in a magnetic recording and reproducing device travels a magnetic tape 2 drawn out from a tape cassette 1 along a rotary head drum 3. The tension arm 14 is rocked according to the tension of the magnetic tape 2, and the rocking position of the tension arm 14 is detected with a photointerruptor 15, and corresponding output is supplied to a control means 18. A braking means 16 applies brake on the rotation of the reel of the supply reel base 6, and the braking force by the braking means 16 is adjusted with a voltage applied on a solenoid 17. The control means 18 controls an impression voltage on the solenoid 17 so as to set the tension arm at a prescribed rocking position based on the output of the photointerruptor 15.</p> |
