Electrophoretic display medium and device
AssigneeXerox Corporation
InventorsNaveen Chopra, Valerie M. Farrugia, Man-Chung Tam, San-Ming Yang, Richard P. N. Veregin, Patricia A. Burns
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Abstract
An electrophoretic display includes one or more set of colored particles in a dielectric fluid, wherein at least one of the one or more set of particles comprise particles having a cationic coating thereon imparting a substantially uniform positive charge to the particles. The display medium is included in an electrophoretic display device by including the medium in a multiplicity of individual reservoirs of a display layer or layers that is located between conductive substrates.
Claims24
An electrophoretic display medium, comprising one or more set of colored particles in a dielectric fluid, wherein at least one of the one or more set of colored particles comprise particles having a cationic polymer coating thereon imparting a substantially uniform positive charge to the particles, and wherein a charge distribution of the particles is such that a charge among any two given particles of the set is within about 20% of each other.
An electrophoretic display medium, comprising one or more set of colored particles in a dielectric fluid, wherein at least one of the one or more set of colored particles comprise particles having a cationic polymer coating thereon imparting a substantially uniform positive charge to the particles, wherein the at least one set of colored particles has a charge of from about 0.1 to about 20 μC/g.
A method of making an electrophoretic display medium comprising one or more set of colored particles in a dielectric fluid, wherein at least one of the one or more set of colored particles comprise particles having a cationic polymer coating thereon imparting a substantially uniform positive charge to the particles, the method comprising
- forming the particles from at least one binder and at least one colorant;
- adding a solution of the cationic polymer to an aqueous suspension of the particles at a pH of 5 or below;
- adjusting the pH of the aqueous suspension of the particles to above 5 to precipitate the cationic polymer onto the surface of the particles;
- and
- dispersing the particles in the fluid.
An electrophoretic display device, comprising a multiplicity of individual reservoirs containing a display medium between conductive substrates, at least one of which is transparent, wherein the display medium comprises one or more set of colored particles in a dielectric fluid, wherein at least one of the one or more set of colored particles comprise particles having a cationic polymer coating thereon imparting a substantially uniform positive charge to the particles, and wherein a charge distribution of the particles is such that a charge among any two given particles of the set is within about 20% of each other.
Dependencies are inferred from the claim text.