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IMPROVEMENTS IN ELECTROPHORETIC DISPLAYS

IP.com Disclosure Number: IPCOM000238608D
Publication Date: 2014-Sep-05
Document File: 7 page(s) / 139K

Publishing Venue

The IP.com Prior Art Database

Abstract

Polymer-coated particles for use in electrophoretic displays, similar to those described in U.S. Patent No. 6,822,782, can be produced using hexafunctional trialkoxysilane monomers. The central organic bridge group of the hexafunctional trialkoxysilane can be varied to tune such properties as chemical functionality, surface area, surface hydrophobicity/hydrophilicity, and refractive index of the final pigment composite. Electrophoretic displays can be provided with illumination for reading in dark environments by providing phosphorescent or electroluminescent particles in the electrophoretic medium, and a backlight behind the backplane of the display, and switching the display to black between each transition, so that the phosphorescent or electroluminescent particles are “charged” by the backlight.

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IMPROVEMENTS IN ELECTROPHORETIC DISPLAYS

This invention relates to improvements in particle-based electrophoretic displays in which one or more types of electrically charged particles are suspended in a liquid and are moved through the liquid under the influence of an electric field to change the appearance of the display.

The background nomenclature and state of the art regarding electrophoretic displays is discussed at length in U.S. Patents Nos. 6,822,782 and 7,012,600 to which the reader is referred for further information. Accordingly, this nomenclature and state of the art will be briefly summarized below.

The term "gray state" is used herein in its conventional meaning in the imaging art to refer to a state intermediate two extreme optical states of a pixel, and does not necessarily imply a black-white transition between these two extreme states. For example, several of the patents and published applications referred to below describe electrophoretic displays in which the extreme states are white and deep blue, so that an intermediate "gray state" would actually be pale blue. Indeed, as already mentioned the transition between the two extreme states may not be a color change at all. The term "gray level" is used herein to denote the possible optical states of a pixel, including the two extreme optical states.

The terms "bistable" and "bistability" are used herein in their conventional meaning in the art to refer to displays comprising display elements having first and second display states differing in at least one optical property, and such that after any given element has been driven, by means of an addressing pulse of finite duration, to assume either its first or second display state, after the addressing pulse has terminated, that state will persist for at least several times, for example at least four times, the minimum duration of the addressing pulse required to change the state of the display element. It is shown in U.S. Patent No. 7,170,670 that some particle-based electrophoretic displays capable of gray scale are stable not only in their extreme black and white states but also in their intermediate gray states, and the same is true of some other types of electro-optic displays. This type of display is properly called "multi-stable" rather than bistable, although for convenience the term "bistable" may be used herein to cover both bistable and multi-stable displays.

Particle-based electrophoretic displays are described in U.S. Patents Nos. 5,930,026; 5,961,804; 6,017,584; 6,067,185; 6,118,426; 6,120,588; 6,120,839; 6,124,851; 6,130,773; and 6,130,774; U.S. Patent Applications Publication Nos. 2002/0060321; 2002/0090980; 2003/0011560; 2003/0102858; 2003/0151702; 2003/0222315; 2004/0014265; 2004/0075634; 2004/0094422; 2004/0105036; 2005/0062714; and 2005/0270261; and International Applications Publication Nos. WO 00/38000; WO 00/36560; WO 00/67110; and WO 01/07961; and European Patents Nos. 1,099,207 B1; and 1,145...