Controlled gap states for liquid crystal displays

A method of imaging a bistable matrix-addressable display element comprising:

• providing a bistable matrix-addressable display element comprising a substrate, a bistable chiral nematic liquid crystal imaging layer having a reflection maximum, at least one conductor, and at least one field-spreading layer between said bistable chiral nematic liquid crystal imaging layer and said at least one conductor, wherein said field-spreading layer has a sheet resistance (SER) of from 10.sup.9 to 10.sup.6 Ohms per square;
• identifying an area to be updated of said bistable matrix-addressable display element, wherein said area to be updated comprises rows of pixels;
• and
• applying a sequence of drive signals having a 4-phase approach to image said bistable matrix-addressable display element, wherein said 4-phase approach comprises:
• in phase 1, applying a first pixel voltage across said pixels of said area to be updated such that the critical voltage is reached;
• and holding said first pixel voltage until a homeotropic texture is reached;
• in phase 2, setting a second pixel voltage to allow said homeotropic texture to relax into a stable planar texture;
• in phase 3, selecting one row of pixels of said rows of pixels of said area to be updated;
• and updating said one row of pixels by addressing, wherein addressing comprises
• applying a third pixel voltage, capable of switching said pixels from said stable planar texture to said non-reflective focal conic texture, across said pixels to produce switched pixels;
• applying a fourth pixel voltage, incapable of switching said pixels from said stable planar texture to said non-reflective focal conic texture, to produce unswitched pixels to remain in the stable planar texture;
• and
• repeating said addressing until said rows of pixels of said area to be updated have been addressed;
• and
• in phase 4, removing said first pixel voltage, said second pixel voltage, said third pixel voltage, and said fourth pixel voltage from said area of said bistable matrix-addressable display element to be updated.