US Patent 9341916 Multi-color electro-optic displays

An electro-optic display comprising at least two separate layers of electro-optic material, with one of these layers being capable of displaying at least one optical state which cannot be displayed by the other layer. The display is driven by a single set of electrodes between which both layers are sandwiched, the two layers being controllable at least partially independently of one another. Another form of the invention uses three different types of particles within a single electrophoretic layer, with the three types of particles being arranged to shutter independently of one another.