Abstract: A method of manufacturing a compensator layer features forming first and second retardation foils by polymerizing or vitrifying liquid-crystalline material comprising liquid-crystal molecules in manner wherein the liquid-crystal molecules in the polymerized or vitrified liquid-crystalline material of the first and second retardation foils respectively exhibit first and second tilt angles which are respectively parallel to first and second planes that are normal to major surfaces of the foils and that are angled with respect to one another by an angle of 60–120 degrees.

Abstract: A method of forming a liquid-crystal display device having a display cell comprises forming retardation foils on substrates using polymerized or vitrified liquid-crystal material wherein the liquid-crystal molecules of the polymerized or vitrified liquid-crystal material have a tilt angle with respect to a plane parallel to the substrates and so that the retardation foils have substantially complementary indicatrices and so that each one of the retardation foils brings about the compensation of approximately half the display cell in the driven state.

Abstract: The invention relates to a liquid-crystal display device comprising a display cell and a plurality of retardation foils of polymerized or vitrified liquid-crystal material, whose liquid-crystal molecules have a tilt angle with respect to a plane parallel to the substrates, which retardation foils have substantially complementary indicatrices so that each one of the retardation foils brings about the compensation of approximately half the display cell in the driven state.

Abstract: A method for manufacturing a broadband cholesteric polarizer includes positioning a layer of reactive material; irradiating the layer of reactive material; directing, at a first side of the layer, a monochromatic beam of light of a given wavelength toward the layer; and detecting, at a second side of said layer, a detected intensity of light of the given wavelength coming from the layer.

Abstract: The Application describes a method and devices for manufacturing a broadband cholesteric polarizer having a well-defined bandwidth and edge position. To this end, a liquid-crystalline cholesterically ordered layer comprising reactive chiral monomers and reactive nematogenic monomers having a different reactivity is polymerized by exposure to radiation. The invention is characterized in that the intensity of the radiation is increased substantially, preferably by a factor of 10 or more, when a desired edge position of the band is reached. As a result, the bandwidth and edge position of the reflection band reached at that moment are frozen as it were. A monochromatic sensor can be used to determine whether said edge position has been reached, the wavelength used by the sensor corresponding to the wavelength of the desired edge position of the band. Broadband, cholesteric polarizers having a well-defined bandwidth and edge position can very advantageously be used in a display.

Abstract: The Application describes a method and devices for manufacturing a broadband cholesteric polarizer having a well-defined bandwidth and edge position. To this end, a liquid-crystalline cholesterically ordered layer comprising reactive chiral monomers and reactive nematogenic monomers having a different reactivity is polymerized by exposure to radiation. The invention is characterized in that the intensity of the radiation is increased substantially, preferably by a factor of 10 or more, when a desired edge position of the band is reached. As a result, the bandwidth and edge position of the reflection band reached at that moment are frozen as it were. A monochromatic sensor can be used to determine whether said edge position has been reached, the wavelength used by the sensor corresponding to the wavelength of the desired edge position of the band. Broadband, cholesteric polarizers having a well-defined bandwidth and edge position can very advantageously be used in a display.

Abstract: A compensator (for example, for a liquid-crystal display device) comprising a retardation foil with a tilted optical main axis and, in addition, a second optically active layer, can be manufactured in a simple manner by providing the retardation foil and the second layer on different sides of a transparent support.

Abstract: A liquid-crystalline cholesterically ordered layer comprising reactive chiral monomers and reactive nematogenic monomers having a different reactivity is polymerized by exposure to radiation. The intensity of the radiation is increased substantially, preferably by a factor of 10 or more, when a desired edge position of the band is reached. As a result, the bandwidth and edge position of the reflection band reached at that moment are frozen as it were. A monochromatic sensor can be used to determine whether said edge position has been reached, the wavelength used by the sensor corresponding to the wavelength of the desired edge position of the band. Broadband, cholesteric polarizers having a well-defined bandwidth and edge position can very advantageously be used in a display.

Abstract: A liquid crystal display cell having a compensation layer of (polymer) material deposited from the gaseous phase. To obtain a smaller angle dependence, the birefringence of the compensation layer is rendered complementary to that associated with a given voltage across the liquid crystal cell by giving the optical axis of the compensation layer an angle to the direction transverse to the cell.

Abstract: 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.

Abstract: 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.

Abstract: An illumination system comprises a radiation source and a broadband, cholesteric polarizer. Such a polarizer includes a layer of a polymeric material having a cholesteric ordering, the material being ordered such that the axis of the molecular helix is oriented transversely to the layer. The broadband character of the polarizer is obtained by increasing the pitch of the molecular helix from a minimum value at a first surface of the cholesteric layer to a maximum value at the second surface of the layer. The polarizer must be positioned in the illumination system in such a manner that the second surface of the cholesteric layer faces the radiation source. By virtue thereof, the illumination system attains a surprisingly low viewing-angle dependence of the brightness and the colour. This property is further improved by using a quarter lambda plate having a negative an isotropy in the refractive index.

Abstract: A liquid crystal display cell having a compensation layer of (polymer) material deposited from the gaseous phase. To obtain a smaller angle dependence, the birefringence of the compensation layer is rendered complementary to that associated with a given voltage across the liquid crystal cell by giving the optical axis of the compensation layer an angle to the direction transverse to the cell.

Abstract: An electro-optic display device with grey scale set by areas of crossing electrodes. In one embodiment, there are 3 strip-shaped sub electrodes with a width relationship of 4:2:1, and two strip shaped column electrodes with a relationship of 8:1. In a second embodiment, there are 4 strip-shaped sub electrodes with a width relationship of 8:4:2:1, and two strip shaped column electrodes with a relationship of 16:1.

Abstract: In a bistable switching display device the occurrence of artefacts due to considerable changes of periodicity between successive grey scale stages is reduced by a suitable subdivision of the electrodes (112). To this end a drive unit (116) allocates fewer than 2.sup.n grey scale stages to each pixel (113) which is subdivided into n sub-pixels (113.sup.a, 113.sup.b, 113.sup.c). The change of periodicity will decrease when a suitable division of the surface ratios and drive sequence are chosen.

Abstract: An LCD device in which the pixels are divided into sub-pixels composed of one analog adjustable sub-pixel and a plurality of digitally controlled other sub-pixels. By combining a discrete adjustment of the (sub)-transmission levels of the other sub-pixels with an analog adjustment of transmission levels of the one sub-pixel, the total number of light transmission levels is increased considerably. The analog adjustment thus is less critical because the greater part of the ultimate level is defined by the accurate discrete adjustment.