Apparatus for compensating for magnetic tape speed variations during playback

Claim 1

APPARATUS FOR REPRODUCING DATA FROM A MOVABLE STORAGE MEDIUM ON WHICH HAS BEEN RECORDED A TIMING SIGNAL OF PREDETERMINED FREQUENCY, SAID APPARATUS COMPRISING: MEANS FOR IMPARTING AN OVER-ALL MOVEMENT TO SAID STORAGE MEDIUM; MEANS, INCLUDING A PLAYBACK HEAD, FOR REPRODUCING FROM SAID STORAGE MEDIUM THE TIMING SIGNAL RECORDED THEREON; MEANS FOR GENERATING A REFERENCE SIGNAL OF A FREQUENCY IDENTICAL TO THAT OF SAID TIMING SIGNAL; MEANS FOR COMPARING THE REFERENCE SIGNAL SO GENERATED WITH THE TIMING SIGNAL REPRODUCED FROM SAID STORAGE MEDIUM TO DEVELOP A FLUCTUATING ERROR VOLTAGE THE MAGNITUDE OF WHICH IS INDICATIVE OF THE EXTENT OF ANY VARIATION IN THE SPEED OF MOVEMENT OF SAID STORAGE MEDIUM DURING REPRODUCTION FROM ITS SPEED OF MOVEMENT DURING THE RECORDING OF SAID TIMING SIGNAL THEREON; AND MEANS FOR APPLYING A CHARACTERISTIC OF SAID ERROR VOLTAGE TO CONTROL THE MOVEMENT OF SAID STORAGE MEDIUM ONLY IN THE IMMEDIATE VICINITY OF SAID PLAYBACK HEAD, SAID LASTMENTIONED MEANS INCLUDING A FRAM FORMED WITH A REENTRANT PORTION AND HAVING MOUNTED THEREON A PAIR OF SPACED-APART ROLLERS OVER WHICH SAID STORAGE MEDIUM SUCCESSIVELY PASSES, SAID PLAYBACK HEAD BEING DISPOSED AT LEAST PARTIALLY WITHIN THE RE-ENTRANT PORTION OF SAID FRAME SO THAT SAID STORAGE MEDIUM DESCRIBES A LOOP IN MOVING PAST SAID HEAD, SAID FRAME BEING PIVOTALLY MOUNTED FOR LIMITED ANGULAR ROTATION ABOUT A SINGLE AXIS LYING INTERMEDIATE SAID ROLLERS INSOFAR AS THE OVER-ALL DIRECTION OF MOVEMENT OF SAID STORAGE MEDIUM IS CONCERNED, SAID AXIS BEING EQUIDISTANT FROM SAID ROLLERS, SAID AXIS ALSO EXTENDING ESSENTIALLY TRANSVERSE TO THE DIRECTION OF MOVEMENT OF SAID MEDIUM PAST SAID PLAYBACK HEAD.