Disclosed is a method of preparing encapsulated bichromal balls. The
method involves forming capsules of electrophoretic particles
encapsulated within a dielectric fluid such as a hydrocarbon solvent or
siloxane oil that includes a small amount of a gelating agent. Bichromal
balls are then formed by heating the capsules and applying an electric
field. The capsules are then cooled while the electric field is
maintained. Upon sufficient gelling, the electrophoretic particles are
fixed within the gelled medium, i.e. the capsule. The bichromal gel
produced detaches from the inside wall of the capsule, and thereby
constitute the resulting encapsulated bichromal balls.