Liquid crystal display device with ridges
AssigneeU.S. Philips Corporation
InventorTheodorus H. M. van den Berk
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Abstract
In a matrix display device using the bistability effect of cholesteric liquid crystals, two supporting plates are provided with first and second pluralities of ridges. The electrodes of the liquid crystal extend across the second ridges onto the first ridges on which a separation strip separates the electrodes from one another. Liquid crystal orienting layers are provided over the entire surface of the supporting plate. The second ridges lying between the first ridges divide each picture element of the display into many sub-elements. Accordingly, the formation of focal-conical texture because of surface inhomogenities in the picture element display will be restricted to a single sub-element as a result of the homeotropic-nematic texture at the edges of the sub-element.
Claims16
In a display device comprising two supporting plates;
- crossing patterns of strip-shaped electrodes on facing surfaces of said supporting plates, said crossing patterns forming a plurality of picture elements;
- orienting layers on said electrodes and exposed surfaces of said supporting plates;
- a layer of cholesteric liquid crystal between said supporting plates, wherein upon applying an electric field across said layer of liquid crystal, said liquid crystal has a focal-conic texture below a first field strength E.sub.1, has a homeotropic-nematic texture above a second field strength E.sub.2, and has one of said two textures for a field strength between E.sub.1 and E.sub.2 ;
- and first means for maintaining said liquid crystal in said homeotropic-nematic texture at edges of said picture elements above said field strength E.sub.2 if said field strength between E.sub.1 and E.sub.2 prevails in a central part of each of said picture elements;
- the improvement comprising second means for dividing each picture element into a number of sub-elements, said second means further maintaining edges of each sub-element in said homeotropic-nematic texture above said field strength E.sub.2 if said field strength between E.sub.1 and E.sub.2 prevails at the area of said picture element.
Dependencies are inferred from the claim text.