| 摘要 |
<p>PURPOSE:To run a magnetic tape with an approximately uniform driving force independently of a coefficient of friction to a tape running guide element by varying a given torque in accordance with the output of a magnetic tape tension detecting means. CONSTITUTION:A tension post 30 is brought into contact with a magnetic tape 3; and when the tension of the magnetic tape 3 is larger, a lever 32 is turned counterclockwise, and the quantity of light to a photodetector 36 is reduced. When the tension of the mganetic tape 3 is smaller, the quantity of light to the photodetector 36 is increased. When the quantity of light to the photodetector 36 is reduced by increase of the tension of the magnetic tape 3, a turning lever 40 is turned clockwise to loosen a tension band 23, and the tension of the magnetic tape 3 is reduced. In the contrary case, the tension of the magnetic tape 3 is increased. Between the magnetic tape 3 and running guide elements in this tape running system, the tape tension in a part H is hardly changed even if a coefficient of friction is changed. Consequently, it is sufficient if the tape driving force due to a capstan 12 and a pinch roller 13 is set in accordance with the case of a smaller coefficient of friction.</p> |
