Tape tensioning apparatus

In a magnetic tape transport, a tape tension arm is loaded by three different springs to exert three different tension forces laterally against the tape segment anchored between the supply reel and capstan (or supply reel and takeup reel), and the arm has three correspondingly different positions for "play," "fast-forward" and "rewind" modes of operation. The play position of the arm is sensed to provide a play tension at substantially the full value thereof throughout a wide range including the play position, and each pair of tensioning force transmitting elements is arranged to move conjointly and in substantially the same direction so as to avoid frictional shearing motion therebetween.

What is claimed is:

1. A tape tensioning apparatus for a magnetic tape transport including a tape element; a pair of spaced tape moving and anchoring means engaging and anchoring said tape at spaced points thereon deferring a tape segment of variable length, and tension loading means coupled to said tape moving and anchoring means and to said tape segment between said spaced points in first and second operating modes to alter the length of said segment between corresponding first and second predetermined length values and to apply corresponding first and second tensioning forces laterally to said segment, characterized in that:

said tension loading means is arranged to apply at least one of said tensioning forces at substantially the full value thereof whenever the actual length value of said segment falls within a predetermined operating range of the corresponding predetermined median length value of the segment; and

said tension loading means includes a set including at least one force-transmitting element, said one thereof engaging said tape element and each element of said set engaging at least one other element of said set, each pair of engaged elements being arranged to move only conjointly and in substantially the same direction, so as to avoid frictional shearing motion therebetween.

2. Apparatus as recited in claim 1, wherein said tape moving and anchoring means comprise a pair of tape storage and transport reels.

3. Apparatus as recited in claim 1 wherein said tape moving and anchoring means comprise a tape supply reel and a capstan and pinch roller assembly downstream from said supply reel in the direction of forward longitudinal motion of said tape.

4. Apparatus as recited in claim 1, wherein said tension loading means includes:

a tension arm mounted for pivoting motion on said transport and a first tension spring anchored to said transport and attached to said arm for applying a moment thereto urging said arm laterally against said tape and tensioning said tape between said tape moving and anchoring means;

said arm having a predetermined first rotational alignment position with respect to said transport when said tension loading means is in said first operating mode thereof.

5. Apparatus as recited in claim 4, wherein said tension loading means also includes:

a second tension spring and a first link member attached at one end to one end of said second spring, the other end of said first link and the other end of said second spring both being anchored to said transport with said second spring tensioned in a preloaded condition;

said first link being adapted to engage said arm to further tension said second spring when said arm rotates a predetermined arcuate distance away from said first rotational alignment position of said tension loading means, so as to alter the spring load of said arm by an amount corresponding to the load of said second spring;

said link having a slot formed therein to provide lost motion anchoring of said link to said transport.

6. Apparatus as recited in claim 5, wherein said tension loading means also has a third operating mode and also includes:

a third tension spring and a second link member attached at one end to one end of said third spring, the other end of said second link and the other end of said third spring both being anchored to said transport with said third spring tensioned in a preloaded condition;

said second link being adapted to engage said arm to further tension said third spring when said arm rotates a predetermined arcuate distance away from said first rotational alignment position toward a third rotational alignment position corresponding to said third operating mode of said tension loading means, so as to alter the spring load of said arm by an amount corresponding to the load of said third spring;

said second link also having a slot formed therein to provide lost motion anchoring of said second link to said transport.

7. Apparatus as recited in claim 6, wherein opposite tape tensioning moments are applied by said second and third springs to said arm.

8. Apparatus as recited in either of claim 5 or 7, wherein the anchoring and attachment structures of said springs, and the engagements of said arm and links are each arranged with confronting tension members one of which has an arcuate surface of smaller diameter than the other so that pivoting movement contact therebetween is substantially frictionless rolling movement

9. Apparatus as recited in claim 8, wherein said lost motion anchoring of said links and transport comprise posts extending from said transport and riding freely in slots defined in said links as of substantially greater widths than the diameters of said posts, so that sliding frictional contact between posts and links is wholly avoided.