The understanding and elimination of some suspension instabilities in an electrophoretic display

Abstract

The performance and appearance of an electrophoretic display is strongly dependent on the stability of the colloidal suspension in the device. Two primary degradation modes in a suspension have been identified. One is classified as pigment agglomeration which is caused by an insufficient repulsive barrier between particles; the other is classified as pigment clustering which is caused by fluid motion within the cell. Both forms of instabilities are detrimental to the life of the display. The concept of colloid stability will be reviewed briefly and its relation to the image device will be discussed. The mechanism by which the suspension instabilities develop and the methods by which they can be eliminated will be described. Properly stabilized suspensions in a device have survived in excess of 2.5×108 switches (15 600 h) with no serious signs of degradation.

Suppression of Phase Separation in LiFePO4 Nanoparticles During Battery Discharge

“…Other examples of this general phenomenon may include transient clustering in electrophoretic displays 53 or delayed shock-induced phase transformations in solids. Homogeneous profiles at high and low concentrations, X(A 2 ) and X(B 2 ) respectively (see Fig.…”

Space charge limited release of charged inverse micelles in non-polar liquids

“…However, not all aspects of the charging dynamics have been clarified. Non-polar liquids with surfactants are used in inkjet printing 1 , liquid toners 12 , electrophoretic image displays [13][14][15] and many others applications [16][17][18][19] .…”

Different Types of Charged-Inverse Micelles in Nonpolar Media

“…Because of the presence of free CIMs, the nonpolar medium becomes more conductive, affecting the electric field and the switching characteristics of charged pigment particles. 21 Controlling the trajectory of particles in conductive media is challenging because of electrohydrodynamic flow, 7,29 which causes particle clustering 7 and pattern formation 35−37 at the electrodes, resulting in image degradation, increased power consumption, and reduced lifetimes of electrophoretic devices. 7 Many effects of charged inverse micelles can be studied without the presence of colloidal particles.…”

“…21 Controlling the trajectory of particles in conductive media is challenging because of electrohydrodynamic flow, 7,29 which causes particle clustering 7 and pattern formation 35−37 at the electrodes, resulting in image degradation, increased power consumption, and reduced lifetimes of electrophoretic devices. 7 Many effects of charged inverse micelles can be studied without the presence of colloidal particles. 29,33,38 The electrical behavior of these nonpolar systems with surfactant is governed by the drift, diffusion, and generation/recombination of CIMs.…”

“…11−15,30−32 Electrophoretic displays are based on the displacement of charged pigment particles between two electrodes in response to an applied voltage. 5,7,25 In these systems, surfactant is often added to charge and stabilize the pigment particles. 16,33,34 However, only a small fraction of surfactant molecules is adsorbed at the particle surfaces and other interfaces.…”