Color selection by mixing primary toners

Abstract

A specified and designated, non-primary color print (imaging) is applied to a substrate (paper) by mixing at least first and second differently colored toner particles having substantially uniform physical characteristics, and introducing them in desired proportions into a fluidized bed. The toner powders are uniformly mixed together in the fluidized bed (as by using rotors in addition to applying fluidizing air to the bed), and then a substantially uniform electrostatic charge (e.g. about +6.5-+8 kV D.C., which can be applied by blades on the rotor) is applied to the bed, and then the electrostatically charged mixture of toner particles is applied to the substrate, to image uniform non-primary color symbols on the substrate. The uniform physical characteristics of the powders are size (the vast majority of particles having a size between about 5 microns and about 25 microns), a resistivity of greater than 10.sup.12 ohm-cm, and a flowability between a predefined minimum and maximum. When utilizing the fluidized bed as according to the invention, slight changes in chemical composition of the toners may be easily accommodated without change in the resulting uniform imaging.