Transducer positioning system

Claim 1

IN A MAGNETIC MEMORY, THE COMBINATION COMPRISING: A CONTINUOUSLY ROTATING MAGNETIC RECORD MEMBER HAVING A PLURALITY OF CONTINUOUS DATA TRACKS WHEREIN DATA REPRESENTATIONS ARE RECORDED; AN ARM HAVING A PORTION COMPOSED OF A MAGNETOSTRICTIVE MATERIAL; A COIL WOUND AROUND SAID MAGNETOSTRICTIVE PORTION; A MAGNETIC HEAD MOUNTED AT ONE EXTREMITY OF SAID ARM AND ADAPTED TO SENSE SAID DATA REPRESENTATIONS, AND TO GENERATE DATA SIGNALS INDICATIVE THEREOF; POSITIONING MEANS ASSOCIATED WITH THE OPPOSITE EXTREMITY OF SAID ARM AND OPERABLE IN RESPONSE TO COARSE POSITIONING SIGNALS TO POSITION SAID MAGNETIC HEAD AT A SELECTED DATA TRACK ON SAID MAGNETIC RECORD AND FURTHER OPERATIVE IN RESPONSE TO A FIRST VERNIER POSITIONING SIGNAL TO MOVE SAID ARM AND SAID MAGNETIC HEAD IN A FIRST DIRECTION TRANSVERSE TO THE SELECTED TRACK, AND TO A SECOND POSITIONING SIGNAL TO MOVE SAID ARM AND SAID MAGNETIC HEAD IN A DIRECTION OPPOSITE TO SAID FIRST DIRECTION; A SINUSOIDAL OSCILLATION GENERATOR CONNECTED TO SAID COIL, SAID COIL INDUCING OSCILLATIONS INTO SAID MAGNETOSTRICTIVE PORTION OF SAID ARM THEREBY RESULTING IN A TRANSVERSE OSCILLATORY MOVEMENT OF SAID MAGNETIC HEAD ACROSS THE SELECTED DATA TRACK, WHEREBY SAID GENERATED DATA SIGNALS ATTAIN A PERIODIC AMPLITUDE MODULATION ENVELOPE; COMPARING MEANS HAVING INPUTS CONNECTED TO SAID SINUSOIDAL OSCILLATION GENERATOR AND SAID MAGNETIC HEAD, AND VERNIER SIGNAL OUTPUTS CONNECTED TO SAID POSITIONING MEANS, SAID COMPARING MEANS GENERATING A SIGNAL ON A FIRST VERNIER SIGNAL OUTPUT WHEN THE OUTPUT OF SAID SINUSOIDAL OSCILLATION GENERATOR AND SAID PERIODIC AMPLITUDE MODULATION ENVELOPE ARE IN PHASE AND A SIGNAL ON A SECOND VERNIER SIGNAL OUTPUT WHEN THE OUTPUT OF SAID SINUSOIDAL OSCILLATION GENERATOR AND SAID MODULATION ENVELOPE ARE OPPOSED IN PHASE; WHEREBY SAID POSITIONING MEANS, IN RESPONSE TO SAID VERNIER OUTPUT SIGNAL, IS CAUSED TO MOVE SAID ARM AND SAID MAGNETIC HEAD TO COMPENSATE FOR UNDESIRED DEVIATIONS OF SAID MAGNETIC HEAD FROM THE OPTIMUM SENSING POSITION FOR SAID SELECTED DATA TRACK.