Developing unit for photocopy machine

Claim 1

IN A DEVELOPING UNIT FOR A PHOTOCOPY MACHINE CAPABLE OF DEVELOPING A COPY SHEET HAVING AN ELECTROSTATIC LATENT IMAGE THEREON, THE COMBINATION COMPRISING A TONER BIN FOR CONTAINING A QUANITY OF TONER MIX INCLUDING A TONER POWDER AND MAGNETIC CARRIER PARTICLES THEREFOR, A MAGNETIC DEVELOPING CYLINDER ROTATABLY MOUNTED IN SAID BIN, MEANS FOR TRANSPORTING THE COPY SHEET THROUGH THE BIN, SAID TONER BIN HAVING A SIDE WALL IN THE FORM OF A SHEET OF NONMAGNETIC MATERIAL OF CURVED CONTOUR TO CONFORM TO THE SHAPE OF THE CYLINDER AND SPACED THEREFROM TO DEFINE A PASSAGE OF UNIFORM WIDTH FOR ADMISSION OF THE COPY SHEET, A LONGITUDINALLY EXTENDING MAGNETIC POLE ARRANGED ON THE OPPOSITE SIDE OF THE NON-MAGNETIC SHEET FOR ESTABLISHING LINES OF FLUX EXTENDING THROUGH THE NON-MAGNETIC SHEET AND COPY SHEET, THE SURFACE OF THE CYLINDER HAVING WELL DEFINED HELICAL RIDGES THEREON FOR CONCENTRATING THE MAGNETIC FLUX AND FOR FORMING HELICAL TUFTS OF TONERS MIX WHICH ARE SWEPT LATERALLY ACROSS THE SURFACE OF THE SHEET AS THE DEVELOPING CYLINDER IS ROTATED THEREBY TO DEPOSIT TONER POWDER IN THE CHARGED AREAS AND FOR SWEEPING TONER POWDER CLEAR OF THE NON-CHARGED AREAS.