Qinetiq Limited

Hewlett-packard Development Company, L.p.

Zbd Displays Limited

Victor Chaklam Hui

John Clifford Jones

Guy Peter Bryan-Brown

Richard Jonathan Miller

Emma Louise Wood

Ian Charles Sage

Carl Vernon Brown

A phoretic display having a liquid crystal suspension medium and a relief structure alignment layer comprising a relief structure surface incorporating a plurality of indentations. The relief structure alignment layer is adapted to generate a preferred alignment of the liquid crystal suspension medium within the display by creating defects within the alignment of the liquid crystal director at the base of each indentation. The relief structure alignment layer provides a substantially planar liquid crystal director alignment in the vicinity of the internal surface of each indentation and a substantially homeotropic liquid crystal director alignment in the vicinity of the relief structure surface and in the bulk of the liquid crystal material.

Phoretic display

A phoretic display device comprising a plurality of electrophoretic or magnetophoretic cells, each having a phoretic particle dispersed within a suspension medium comprising a liquid crystal material. The phoretic cell is adapted to induce defects, sometimes known as disclinations, in the alignment of the liquid crystal material within the cell which act to exert a retentive force on the phoretic particle when within the region of influence of the defects. The configuration of the display introduces a threshold level in the electric or magnetic field required to move the phoretic particle between defects within the cell. Accordingly, the non-linear electro-optic or magneto-optic behaviour of the display facilitates matrix addressing of the cells therein. The display may comprise a plurality of prolate spheroid phoretic cells arranged in an encapsulant, the major (long) axis of each cell arranged substantially perpendicular to the plane of the display.

Phoretic display device with liquid crystalline suspension medium, and manufacturing method

Liquid crystal devices are described that exhibit bistable, tri-stable or other multistable operation. The stable liquid crystal configurations are attained using a surface alignment grating () on the internal surface of at least one cell wall (). The surface profile of the surface alignment grating comprises three or more defect sites per grating period and permit the liquid crystal molecules to adopt any one of two or more stable pretilt angles in the same azimuthal plane. Application of a suitable voltage causes the liquid crystal material to switch between the stable configurations.

Liquid crystal device

Liquid crystal devices are formed by a layer of a liquid crystal material enclosed between two cell walls, both carrying electrode structures, and one or both walls treated to align molecules of the liquid crystal material. Most alignment treatment give alignment and surface pretilt with a strong azimuthal and zenithal anchoring energy to contacting liquid crystal molecules. The invention reduces at least one of the azimuthal zenithal or translational anchoring energy to improve switching characteristics and optical performance by allowing movement of liquid crystal molecules at or close to the cell wall. The reduction of anchoring energy may be achieved by an oligomer or short chain polymer which is either spread on the surface or added to the liquid crystal material. The size of oligomer or short chain polymer is low enough that it does not appreciably phase separate from the liquid crystal material. The polymer layer has the characteristics of having imperfect solubility in the liquid crystal material used in the device, of having a physical affinity for the surface of the substrate, and of retaining a substantially liquid like surface at the polymer/liquid crystal interface. The polymer may be formed by polymerisation of reactive low molecular weight materials in solution in the liquid crystal fluid. The resulting solution or dispersion of polymer in liquid crystal is then filled into the cell, and the polymer is allowed to coat the substrate surfaces.

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Malvern, United Kingdom

Victor Chaklam Hui