This invention relates to a process for the preparation of a dispersion comprising coloured or black particles, such coloured or black particles prepared by the process, the use of the dispersion and the coloured or black particles in electrophoretic fluids, and electrophoretic display devices comprising such fluids.

An electrophoresis dispersion liquid includes first electrophoretic particle of a scattering system having an ionic group on a surface thereof; second electrophoretic particle of a coloring system having a polarization group on the surface thereof; and a dispersion medium. It is preferable that the ionic group is an acidic group, and further includes a ring structure that forms an acidic group and a salt. It is preferable that the polarization group is an organic group having a main skeleton, and a substituent bonded to the main skeleton.

There is provided a method of manufacturing an electrophoretic particle, in which the electrophoretic particle includes a mother particle and a block copolymer, including: a step of polymerizing a monomer M having a site contributing to dispersibility into a dispersion medium, a monomer M including a second functional group having reactivity with the first functional group, a charged monomer M by living polymerization without random copolymerizing the monomer M1 and the monomer M2 so as to obtain the block copolymer; and a step of reacting the first functional group and the second functional group to a bonding section to a mother particle so as to connect the block copolymer to the mother particle.

The present invention relates to optoelectronics and may be adapted to visualization, display, storage and information processing units and systems, such as 2D and 3D displays, including computer and television ones, light modulators, including, image processing and recognition devices, etc. The object of the present invention is an electro-optical cell which operates in both the transparent and reflective modes. The technical result is to provide a high rate of switching between states with different optical densities. This technical result is achieved by the following way: an electro-optical cell contains two dielectric plates at least one of which is transparent, which dielectric plates are coated on the internal surfaces with transparent conductive layers having terminals for connection to a power supply, wherein according to an embodiment of the invention, between said plates a nonpolar-fluid-based suspension is placed containing particles of elongated shape, opposite end portions of which carry different electric charges.

A display unit of the present disclosure includes a display layer and a color filter. The display layer has a plurality of pixels each including an electrophoretic element. The color filter is provided on a display side of the display layer on a portion of each of the pixels. The electrophoretic element in each of the pixels includes migrating particles, and one of the migrating particles and the color filter is a primary color, and the other is a color complementary to the primary color.

An electrophoretic medium includes a fluid, a first, light scattering particle (typically white) and second, third and fourth particles having three subtractive primary colors (typically magenta, cyan and yellow); at least two of these colored particles being non-light scattering. The first and second particles bear polymer coatings such that the electric field required to separate an aggregate formed by the third and the fourth particles is greater than that required to separate an aggregate formed from any other two types of particles. Methods for driving the medium to produce white, black, magenta, cyan, yellow, red, green and blue colors are also described.

Provided is a driving device of a display medium, including an application unit that applies a voltage with a pulse width corresponding to a density of a color to be displayed to each of plural pixels of a display medium in which plural kinds of particle groups having different movement starting voltages for movement between a pair of substrates according to an electric field and different colors are enclosed, and a controller that controls the application unit so that a first voltage with a pulse width corresponding to a density of a color of a first particle group finishes being applied to each of the plural pixels, and then a second voltage with a pulse width corresponding to a density of a color of a second particle group is applied thereto.

A particle dispersion and the display devices in which the dispersion may be incorporated are provided. The particle dispersion includes a dispersion medium, one or more types of particle groups that are dispersed in the dispersion medium that may differ based on color and/or charge, and counter-ions oppositely charged than the one or more particle groups. The particle groups and counter-ions are moved in the dispersion medium according to an electric field formed in the dispersion medium. The one or more types of particle groups are configured such that the total amount of charges of one type of particle group (a) among the one or more types of particle groups is greater than a total amount of charges of the counter-ions that are charged with a polarity opposite to that of the particle group (a).

The present invention is directed to an electrophoretic fluid which comprises additive particles. The concentration of the additive particles in the electrophoretic fluid is 2.5% to 25% by weight and the additive particles are not seen at the viewing side during operation of the display. The resulting fluid can improve optical performance of a display device, such as image stability and contrast ratio. The present invention is also directed to an electrophoretic display comprising the electrophoretic fluid.

A multi-color electrophoretic medium contains first, second and third species of particles. The first species of particles is light-scattering, while the second and third species of particles are transmissive. A method for driving such a display is also described.