Magnetic tape apparatus for eliminating a slack of magnetic tape when changing a tape winding direction

A magnetic tape apparatus in which data is recorded on or reproduced from a magnetic tape when the magnetic tape is run on a rotary drum, said apparatus comprising:

• a tension regulating unit regulating a tension of the magnetic tape when the magnetic tape is run, said tension regulating unit pressing the magnetic tape at a first position in a tension-applying direction;
• and
• a slack preventing unit, associated with said tension regulating unit, exerting a rotating force on said tension regulating unit at a second position such that said rotating force exerted at the second position acts on said tension regulating unit at the first position to further press the magnetic tape in the tension-applying direction, thus preventing a slack of the magnetic tape from being produced when changing a tape winding direction of the magnetic tape
• wherein said tension regulating unit comprises a tension regulator arm rotatably supported on a rotating shaft, and a tension post attached to said tension regulator arm, said tension post pressing the magnetic tape in the tension-applying direction at the first position, and
• wherein said slack preventing unit exerts a rotating force FA on said tension regulator arm at the second position, said rotating force FA being defined by the formula:
• FT.multidot.L1>FA.multidot.L2, where FT is a reaction force of the magnetic tape on said tension post, L1 is a distance between the rotating shaft and the first position, and L2 is a distance between the rotating shaft and the second position.