U.S. Philips Corporation

Koninklijke Philips Corporation N.v.

Flat Panel Display Co. B.v.

Flat Panel Display Co. (fpd) B.v. Prof. Holstlaan 4

Flat Panel Display Co. (fdp) B. V.

Frans Leenhouts

Dirk Jan Broer

Grietje Neeltje Mol

Johannes A Van Haaren

Jacob Bruinink

Peter Van De Witte

Glenn Adler

Peter B Wolfs

Nicolaas Ajm Van Aerle

Joost Peter Andr&eacute; Vogels

This invention relates to a liquid crystal display device, comprising at least one retardation film ( ), a nematic liquid crystal layer ( ), and a light reflecting RGB patterned cholesteric color filter ( ), for reflecting either essentially left-circular or right-circular polarized light, being characterized in that said liquid crystal layer ( ) is a super twisted nematic liquid crystal layer having a twist angle in the interval 180-270 degrees, and in that the summed retardation R of the retardation film or retardation films and the liquid crystal layer is equal to approximately R&equals;(3&plus;2n)&lgr;/4, where n&equals;0,1,2,3 . . . .

Liquid crystal reflective display

Manufacture of a display device for a touch panel display, for example, an LCD ( ) is simplified by attaching parts of the display panel, for example, a light-scattering film ( ) and a polarizer ( ) to a substrate ( ) of the touch panel ( ).

Touch sensor display

In a touch panel display, a substrate ( ) of the touch panel ( ) or the touch panel itself is used as an optical guide for lighting a reflective display ( ).

A plasma-addressed liquid crystal color display device comprising a layer of liquid crystal material, data electrodes coupled to the liquid crystal layer and adapted to receive data voltages for activating pixels of the liquid crystal layer, and a plurality of ionizable-gas-filled plasma channels extending generally transverse to the data electrodes for selectively switching on said liquid crystal pixels. The plasma channels are sealed off by a thin dielectric sheet. To reduce the magnitude of the data voltages needed to activate the device, the LC layers are given compositions such that a much higher fraction of the applied data voltages appears across the liquid crystal layer thereby allowing a smaller data voltage to be used to obtain the same effect on the liquid crystal pixels.

Plasma-addressed liquid crystal display with reduced column voltages

The invention relates to a color filter layer of a cholesterically ordered material, in which the axis of the molecular helix is directed perpendicularly to said layer. According to the invention, the color filter layer comprises at least one dye which is able to absorb undesired colors caused by color shifts. A correct choice of the bandwidth of the primary colors of the color filter layer and the dyes significantly alleviates the problem of undesired color shift. The invention also relates to a liquid crystal color display device of the reflective type, which is provided with such a color filter layer.

Color filter layer of cholesterically ordered material, and reflective LCD provided with such a color filter layer

The invention provides active-matrix display devices with non-linear two-pole switching elements such as MIMs or three-pole switching elements such as TFTs having a smaller difference in charge current at a different image content by using a suitable. ##EQU1## This leads to less burn-in of the image to be displayed. Moreover, a satisfactory transmission characteristic is obtained at a higher value of .epsilon..sub..perp.. For TFTs it is then possible to use smaller auxiliary capacitances due to the higher values of (.epsilon..sub..perp.). The latter aspect may in turn be utilized to realise a larger aperture.

Liquid crystal display device

Nematic liquid crystal display device, in which the isocontrast curve has obtained a more symmetrical shape by combining two and four sub-pixels with twist angles which are smaller than 90 degrees, at which the sub-pixels are obtained by providing different orientation directions (11) in an orienting layer (8) by means of linearly polarized light. If a cholesteric nematic liquid crystal material is used, a sub-pixel may have a twist angle of more than 90 degrees, while pairs of sub-pixels then have twist angles of opposite twist sense, at which the sum of the absolute values of the twist angles is smaller than 180 degrees.

Multi-domain LCD with subpixels having twist angles with opposite twist

The Application relates to an illumination system comprising a fluorescent lamp and a broadband, cholesteric polarizer. Such a polarizer contains a layer of a polymeric material having a cholesteric order, which material is ordered in such a way that the axis of the molecular helix extends at right angles to the layer. The broadband character of the polarizer is obtained by causing the pitch of the molecular helix to increase from a minimum value at a first surface of the cholesteric layer to a maximum value at the second surface of the layer. In accordance with the invention, the polarizer should be positioned in the illumination system in such a manner that the cholesteric layer is directed towards the fluorescent lamp with its first surface. In addition, the value of the product p.sub.max.n.sub.e of the maximum value of the pitch in the cholesteric layer p.sub.max and of the extraordinary refractive index n.sub.e must range between 0.61 micron and 0.76 micron. By virtue of these measures, the illumination system has a surprisingly low viewing-angle dependence of the lightness and the color. The Application further relates to a linear polarizer for use in this illumination system as well as to a display device which comprises such a linear polarizer.

Illumination system using cholesteric polarizer, linear polarizer for

In a liquid crystal display device the number of grey levels is increased by means of a compensation foil comprising a layer having a cholesteric ordering with a helix pattern, in which the pitch of the helix is smaller than (0.26-0.31..DELTA.n) .mu.m, in which .DELTA.n is the optical anisotropy of the anisotropic layer. Moreover, the viewing angle dependence will be more symmetrical by patterning the cholesteric ordering.

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Eindhoven, Netherlands

Frans Leenhouts