| 摘要 |
<p>PURPOSE:To make it possible to apply a tension arm device to a magnetic tape device having a short rising time by carrying a short auxiliary tension arm so that the vluctuations during the rise and break of the tape may be absorbed by an auxiliary tension arm having a small inertia. CONSTITUTION:A main tension arm 12 is coupled to a bearing 22 and is supplied with a tension from a spring 21. A rotational angle detector 23 is attached to the shaft of the arm 12, and an auxiliary tension arm 11 having a roller 10 is attached rotatably to the leading end of the arm 12 by means of a pin 25. There are provided stoppers 15 and 15' for regulating the rotational angle of the arm 11 together with a film-shaped mask 18 for detecting the rotational angle such that they are made movable between a light source 16 and an optical detector 17 which are attached to the main arm. The auxiliary arm is supplied with a tension from a stationary arm 13 and a spring 14. When a tape running speed is accelerated, the fluctuation in the tape tension are decreased by the rotations about a pin 25 because the inertia of the auxiliary arm 11 is small.</p> |
