Production of magnetic sound recording tape

Claim 1

IN THE METHOD OF PRODUCING MAGNETIC RECORDING TAPE WHEREIN A LONG NARROW NON-MAGNETIC TAPE BASE FROM A ROLL IN AN UNWINDING ZONE IS PASSED THROUGH A MAGNETIC COATING ZONE, WHERE A VERY THIN LAYER OF A DISPERSION OF FINELY DIVIDED PARTICLES OF MAGNETIC OXIDE OF IRON IN A LIQUID VEHICLE FORMED OF A BINDER AND A SOLVENT IS DEPOSITED ON ONE SIDE OF THE TAPE BASE, AND A MAGNETIC COATDRYING ZONE, AND IS WOUND INTO A ROLL IN A WINDING ZONE, THE IMPROVEMENT WHICH COMPRISES PASSING THE COATED TAPE BASE IN A GENERALLY HORIZONTAL DIRECTION THROUGH A MAGNETIC FIELD HAVING ITS SOURCE AT THE UNCOATED TRANSVESE SIDE OF THE NON-MAGNETIC TAPE BASE AFTER IT IS FRESHLY COATED WITH THE LIQUID DISPERSION OF MAGNETIC OXIDE OF IRON PARTICLES AND BEFORE THE COATING IS FINALLY DRIED, THE MAGNETIC FIELD HAVING ITS LINES OF FORCE IN A DIRECTION GENERALLY LONGITUDINAL OF THE TAPE BASE AND BEING SUFFICIENTLY STRONG TO ORIENT THE IRON OXIDE PARTICLES IN THE SOFT COATING SO THAT THEIR MAGNETIC AXES ARE IN A DIRECTION GENERALLY LENGTHWISE OF THE TAPE BASE, THE IRON OXIDE PARTICLES BEING ORIENTED IN A PLURALITY OF SUPERPOSED LEVELS WITHIN THE DEPTH OF THE SOFT COATING, EVAPORATING LIQUID FROM THE BINDERSOLVENT IN THE COATING TO HARDEN THE SAME PARITALLY WHILE THE IRON OXIDE PARTICLES PASS THROUGH THE MAGNETIC FIELD IN A SMOOTH PATH OF TRAVEL TO PLACE THE ORIENTED IRON OXIDE PARTICLES IN A SUBSTANTIALLY QUIESCENT STATE RELATIVELY TO EACH OTHER AND HENCE NOT TO DISTURB THEIR ORIENTED POSITION, MAINTAINING THE IRON OXIDE PARTICLES IN THEIR QUIESCENT ORIENTED POSITION WHILE THE COATING DRIES AND HARDENS SUFFICIENTLY TO FIX THE PARTICLES IN SAID POSITION, AND COMPLETING THE DRYING OF THE PARTIALLY HARDENED COATING WHILE THE IRON OXIDE PARTICLES ARE SO ORINETED, THE RATE OF WINDING THE COATED TAPE BASE AND THE RATE OF UNWINDING THE UNCOATED TAPE BASE BEING CONTROLLED TO REGULATE THE TENSION IN THE TAPE BASE BETWEEN THE UNWINDING AND WINDING ZONES TO PERMIT THE FORMATION OF AN INTERVENING LOOP OF THE TAPE BASE, AND THE ADVANCING FRESHLY COATED TAPE BASE DRIPPING IN A SHALLOW, DEPENDING AND CONTINUOUSLY FORMING, LOOP AS IT PASSES THROUGH THE MAGNETIC FIELD SO THAT THE MAGNETIC PARTICLES TRAPPED IN THE LOOP ACQUIRE A ROLLING MOTION TO FACILITATE THEIR ORIENTATION.