Patent ID: 7652656

Claim:
A method of displaying an image in an electrophoretic display device that is comprised of at least one display layer, including a multiplicity of individual reservoirs containing a display fluid, between conductive substrates, at least one of which is transparent, wherein the display fluid comprises at least three sets of particles in a liquid medium, the at least three sets of particles each exhibiting a different color, wherein a first set of particles and a second set of particles have a same charge polarity with the first set of particles having a higher average charge than the second set of particles, and wherein a third set of particles has a charge polarity opposite that of the first and second set of particles, the method comprising charging each of the sets of differently colored particles to have a desired charge through application of a charging electric field to the display fluid, followed by applying an electric field to selected ones of the multiplicity of reservoirs to effect movement of one or more of the differently colored sets of particles in the display fluid therein to display a desired color derived from among the sets of differently colored particles, wherein a color of the third set of particles is displayed by applying the electric field across the conductive substrates to attract the third set of particles to a front viewing conductive substrate of the device, a color of the first set of particles is displayed by applying the electric field across the conductive substrates, in an opposite polarity than applied for display of the color of the third set of particles, to attract the first set of particles to the front viewing conductive substrate of the device, and a color of the second set of particles is displayed by applying the electric field across the conductive substrates, in an opposite polarity than applied for display of the color of the third set of particles, to attract the first and second set of particles to the front viewing conductive substrate of the device, which displays a color of the first set of particles due to the first set of particles' higher average charge, and then momentarily switching the polarity of the electric field until the first set of particles is moved toward a rear conductive substrate and past the second set of particles and removing the electric field before the second set of particles is moved past the third set of particles.