A variety of methods for driving electro-optic displays so as to reduce visible artifacts are described. Such methods include (a) applying a first drive scheme to a non-zero minor proportion of the pixels of the display and a second drive scheme to the remaining pixels, the pixels using the first drive scheme being changed at each transition; (b) using two different drive schemes on different groups of pixels so that pixels in differing groups undergoing the same transition will not experience the same waveform; (c) applying either a balanced pulse pair or a top-off pulse to a pixel undergoing a white-to-white transition and lying adjacent a pixel undergoing a visible transition; (d) driving extra pixels where the boundary between a driven and undriven area would otherwise fall along a straight line; and (e) driving a display with both DC balanced and DC imbalanced drive schemes, maintaining an impulse bank value for the DC imbalance and modifying transitions to reduce the impulse bank value.

The invention more particularly relates to a method and device for controlling a segmented electrophoretic display. Such displays, preferably covered by the invention, comprise a layer (or a film) of microcapsules containing colored particles suspended in a fluid or a gas, the same layer being sandwiched between two electrodes: at least one first electrode having the shape of the segment to be displayed a second transparent electrode made by a conductive layer of indium tin oxide (ITO) for example. Alternative electrodes based on a thin film of carbon nanostructures, silver or copper wires can also be used.

An electrophoretic medium comprises 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.

A color electrophoretic display with distinct switching areas formed by a segmented top plane electrode opposite driving pixel electrodes. The distinct areas are programmed to switch at different times, thereby reducing the “flashiness” seen by a viewer during an image update. In one embodiment, the color electrophoretic medium of the display includes a reflective white particle and three other sets of particles, each comprising a different subtractive color.

The application provides a method for driving a color electronic paper, including: according to an image to be displayed, applying a first driving signal to a first electrode on a to-display-white microcapsule and a second driving signal to a first electrode on a to-display-black microcapsule. The first driving signal includes: a first sub-driving signal applied to the first electrode on the to-display-white microcapsule in display phase; and the first sub-driving signal is configured to drive a white particle in the to-display-white microcapsule to be closer to a display side than a black particle and a colored particle. The second driving signal comprises: a second sub-driving signal applied to the first electrode on the to-display-black microcapsule in display phase, and the second sub-driving signal is configured to drive the black particle in the to-display-black microcapsule to be closer to the display side than the white particle and the colored particle.

The present invention provides four-particle electrophoretic displays with improved driving methods to achieve better color separation between adjacent pixel electrodes. The driving methods improve the color state performance when a first pixel is displaying a mixed state of a first highly-charged particle and a second lower-charged particle of the opposite polarity, while a neighboring pixel is displaying a state of a second highly-charged particle having the opposite polarity to the first highly-charged particle. The particles can be, for example, all reflective or one type of particle can be partially light transmissive.

An electrophoretic medium comprises a fluid and first (B), second (Y), third (R) and fourth (W) particles dispersed in the fluid and having differing colors. The first (B) and third (R) particles bear charges of one polarity and the second (Y) and fourth (W) particles bear charges of the opposite polarity, The first particles (B) have a greater zeta potential than the third particles (R), and the second particles (Y) have a greater zeta potential than the fourth particles (W). One of the particles (W) is white, one of the non-white particles (B) is partially light-transmissive, and the remaining two non-white particles are light-reflective. To display the color of a mixture of the first (B) and second (Y) particles at a viewing surface, the medium is driven to display the second particles (Y) at the viewing surface, then a first driving voltage is applied for a first period to drive the second (Y) and fourth (W) particles towards the viewing surface, then a second driving voltage, of opposite polarity to and lower magnitude than, the first voltage, is applied for a second period less than the first period, and finally the applications of the two driving voltages are repeated.

The present invention provides improved driving methods for four particle electrophoretic displays that improves the performance of such displays when they are deployed in low temperature environments and the displays are required to be updated when positioned vertically (i.e., the driving electric fields are substantially perpendicular to the direction of Earth's gravity). Methods are provided for displaying each of the colors at each pixel, as desired, with minimal interference (contamination) from the other particles.

A method of driving an electro-optic display including a layer of electro-optic material disposed between a common electrode and a backplane including an array of pixel electrodes, each coupled to a transistor including a source, gate, and drain electrode. The gate electrode is coupled to a gate line, the source electrode is coupled to a scan line, and the drain electrode is coupled to the pixel electrode. A controller provides time-dependent voltages to the gate, scan, and common electrodes, including a common electrode that is the maximum voltage the controller is capable of applying, and a scan line voltage to every pixel that is the maximum voltage the controller is capable of applying. A gate voltage sufficient to activate the pixel transistor to the gate of every pixel transistor is applied, thereby applying voltage potential across the electro-optic material.

A variety of methods for driving electro-optic displays so as to reduce visible artifacts are described. Such methods includes updating a display having a plurality of display pixels with a first image, identifying display pixels with edge artifacts after the first image update, and storing the identified display pixels information in a memory. In particular, the methods are effective for minimizing edge ghosting when a pixel of an active matrix electrophoretic display undergoes a white to white transition or a black to black transition during an update between first and second images.