Patent ID: 8405591

Claim:
A method for control of a nematic bistable liquid crystal display implementing a breaking of anchorage and an active addressing mode, said display including two stable liquid crystal textures, one of these two textures being a uniform or slightly twisted (U) in which liquid crystal molecules are substantially parallel to each other, and the second texture (T) differing from the first texture by a twist of about +/−180° to within +/−15° and said display including a matrix of pixels arranged in crossed lines and columns, said lines being associated with an index n and said columns being associated with an index m, each pixel (P, n, m) situated at an intersection of a line n and a column m, and in which a switching of state of the liquid crystal molecules of a pixel P to a given texture which is one of (i) a uniform or slightly twisted texture (U), and (ii) twisted texture (T), or a combination of the two textures U and T leading to a level of grey, is controlled by application of an electrical control signal between two electrodes ( 50 , 52 ) framing each pixel, the electrical control signal comprising a voltage greater than a voltage for breaking the anchorage and then an active falling edge to obtain the given texture, and said switching generates a flow of liquid crystal molecules in a particular direction ( 18 ) close to a brushing direction ( 40 ), the brushing direction of the display being orthogonal to the lines, addressing of the pixels being operated in two stages made up of a first stage in which addressing of at least part of the display in a unique twisted texture (T) is collectively carried out and then a second stage in which addressing of said part of the screen is carried out line by line, wherein to control the switching of at least some of the pixels (P, n, m), said method comprises applying to at least one pixel ( 58 ) adjacent in a flow direction of a second pixel (P, n, m) wherein the switching is controlled by the electrical control signal, the adjacent pixel (n+1, m) being on the same column m as the second pixel (P, n, m) to switch and on the next line, auxiliary electrical signals corresponding to signals applied onto the electrode of column m suitable to induce in the adjacent pixel an auxiliary flow parallel to said direction ( 18 ), said auxiliary signals being applied during the second stage of addressing the line n of the second pixel (P, n, m) to switch to the given texture, amplitude of the auxiliary electrical signals being less than the breakage voltage and wherein rising or falling edges are temporally placed in advance of or in coincidence relative to active falling edge of the electrical control signal, of the second pixel P with temporal offset of between 0 and 50 microseconds, at ambient temperature, so as to favor the switching of said second pixel to be controlled to the given texture.