Electrophoretic displays with expanded color palettes

A method of driving a color display, wherein the color display comprises (i) an electrophoretic display comprising a light-transmissive electrode at a display viewing surface, an array of pixel electrodes, and an electrophoretic medium disposed between the light-transmissive electrode and the pixel electrodes, the electrophoretic medium comprising multiple types of electrophoretic particles having different optical properties dispersed in a non-polar fluid, wherein each pixel electrode is associated with a display pixel, and wherein the electrophoretic display is capable of producing a plurality of primary colors and variations in hue, saturation, and/or luminance of the primary colors at each display pixel;

• (ii) a display controller circuit;
• and (iii) a non-transitory memory storing a set of primary color waveforms for driving each display pixel to a corresponding primary color and for storing a set of scaling factors to be applied to one of the primary color waveforms to drive each display pixel to a targeted variation of the primary color, the method, performed by the display controller circuit, comprising:
• (a) receiving an image to be displayed on the electrophoretic display;
• and
• (b) driving each display pixel of the electrophoretic display to a targeted color state by applying time-dependent voltages of waveforms between the pixel electrodes and the light-transmissive electrode to render the image, wherein to produce a primary color at a display pixel, a primary color waveform corresponding to the primary color is selected from the set of primary color waveforms and applied to the display pixel, and wherein to produce a variation of a primary color at a display pixel, a scaling factor corresponding to the variation is selected from the set of scaling factors and applied to the corresponding primary color waveform to generate a scaled waveform, and the scaled waveform is applied to the display pixel.