Quantitative photometric materials sorter

Claim 1

IN A SORTING SYSTEM FOR SORTING ORE FRAGMENTS THE COMBINATION COMPRISING, A VERTICALLY EXTENDING SORTING ZONE, HANDLING MEANS FOR INTRODUCING SAID FRAGMENTS IN SINGLE ROW ALIGNMENT INTO THE UPPER PART OF SAID SORTING ZONE FOR FREE FALL THERETHROUGH, A FIRST LIGHT SOURCE FOR DIRECTING INTO SAID ZONE A STEADY LIGHT POLARIZED IN A FIRST DIRECTION, A FIRST PHOTOMETRIC DETECTOR MEANS ADAPTED TO RECEIVE DIFFUSE LIGHT REFLECTED FROM EACH FRAGMENT AS IT PASSES THROUGH SAID ZONE, A POLARIZED FILTER POSITIONED IN THE PATH OF LIGHT TRAVELLING TOWARDS SAID FIRST PHOTOMETRIC DETECTOR MEANS, SAID POLARIZED FILTER BEING POLARIZED IN A SECOND DIRECTION SUBSTANTIALLY AT RIGHT ANGLES TO SAID FIRST DIRECTION TO REDUCE THE AMOUNT OF SPECULAR REFLECTED LIGHT REACHING SAID FIRST PHOTOMETRIC DETECTOR MEANS, A REFERENCE REFLECTOR OF MATERIAL WHICH RELFECTS A HIGH PROPORTION OF DIFFUSE LIGHT POSITIONED TO RECEIVE LIGHT FROM SAID FIRST LIGHT SOURCE AND REFLECT IT TOWARDS SAID FIRST PHOTOMETRIC DETECTOR MEANS, A ROTATABLE SCANNING DISC ADJACENT A SLOTTED MASK IN THE PATH OF LIGHT REFLECTED TOWARDS SAID FIRST PHOTOMETRIC DETECTOR MEANS WHEREBY SAID FIRST PHOTOMETRIC DETECTOR IS EXPOSED TO LIGHT REFLECTED FROM SUCCESSIVE SCANNED PORTIONS OF EACH SAID FRAGMENT INTERSPRESED WITH LIGHT REFLECTED FROM SAID REFERENCE REFLECTOR, SAID FIRST PHOTOMETRIC DETECTOR MEANS PROVIDING A FIRST SIGNAL HAVING PORTIONS INDICATIVE OF THE REFLECTANCE CHARACTERISTIC OF THE SCANNED SURFACE OF EACH FRAGMENT INTERSPERED WITH PORTIONS INDICATIVE OF THE REFLECTANCE OF SAID REFERENCE REFLECTOR, CONTROL MEANS RESPONSIVE TO THAT PORTION OF SAID FIRST SIGNAL CAUSED BY THE SCANNING OF SAID REFERENCE REFLECTOR TO CONTROL THE OUTPUT OF SAID FIRST PHOTOMETRIC DETECTOR MEANS SO THAT THE PORTION OF THE FIRST SIGNAL CAUSED BY THE SCANNING OF SAID REFERENCE REFLECTOR REMAINS AT A SUBSTANTIALLY CONSTANT AMPLITUDE, A SECOND LIGHT SOURCE POSITIONED ABOVE THE LEVEL OF SAID FIRST PHOTOMETRIC DETECTOR AND HAVING A TRANSVERSE SLOT PROJECTING A THIN BEAM OF LIGHT ACROSS THE PATH OF SAID FRAGMENTS THROUGH SAID SORTING ZONE, A SECOND PHOTOMETRIC DETECTOR MEANS POSITIONED ON THE OPPOSITE SIDE OF SAID