Abstract: A liquid crystal switchable color filter switches between three color bands and is preferably used for time-sequential devices, such as projection devices, direct view displays and video cameras. The color filter may employ circularly polarizing selective reflection bands of at least four cholesteric filters together with three liquid crystal switches and related retarder layers. In one embodiment, the handedness of the second cholesteric is equal to the handedness of the third cholesteric filter and opposite to the handedness of the first and fourth cholesteric filter and, for the blocking state of a color band, the optic axis of the corresponding liquid crystal switch is parallel or perpendicular to the polarization direction. This concept leads to improved, excellent color saturation and requires less stringent production tolerances than in the prior art. Moreover, it advantageously allows overlapping color transmission bands thus improving the light efficiency.

Abstract: Compensation of a liquid crystal display can be achieved using a compensation structure, having, in the following order: a) a first o-plate; b) a first retarder; c) a liquid crystal cell; d) a second retarder; and e) a second o-plate. The first and second retarders can be c-plates or biaxial retarders.

Abstract: Compensation of a liquid crystal display can be achieved using a compensation structure, having, in the following order: a) a first o-plate; b) a first retarder; c) a liquid crystal cell; d) a second retarder; and e) a second o-plate. The first and second retarders can be c-plates or biaxial retarders.

Abstract: A color switch is provided for selectively switching between color bands for use, for example, in projection optics and direct view optics. The color switch has fewer and thinner layers than in the prior art, but exhibits equal or better color purity and light efficiency. The color switch or filter includes a first filter section for selectively blocking green light and including a cholesteric filter, a quarter wave plate and a liquid crystal switch. The color filter has a second filter section for selectively blocking blue and/or red light including a stack of retarder elements and liquid crystal switches, preferably Deformed Helical Ferroelectric (DHF) switches. The parameters of the filter are determined by an optimization process including minimizing a cost function (G) with respect to the parameters of the second filter section. A polarizing element may be positioned in front of the stack and may be of a type which does not absorb radiation.

Abstract: A major disadvantage of known reflective displays consists in the fact that they ideally have a switching angle of ±45° in the so-called symmetric mode. With the liquid crystal mixtures known to date, this is not possible without hysteresis effects occurring even at small switching angles and resulting in the switching time being increased to an impermissible extent. The invention relates to a novel reflective, ferroelectric display which can be actuated without DC voltage and has a maximum switching angle &agr; which is ±22.5°. The liquid crystal display according to the invention is distinguished in particular by the fact that a further birefringent element is arranged between the two plates bounding the birefringent liquid crystal layer.

Abstract: A liquid crystal device comprising ferroelectric liquid crystal material aligned by a liquid crystal polymer (LCP) network layer (18) under 20 nm thick, which itself was aligned by a photo-oriented linearly photopolymerized (LPP) layer (16) under 20 nm thick, exhibits low voltage drop over the aligning layer and has a remarkable contrast ratio.

Abstract: Liquid cell crystal, with fine structures made up of regions having defined different orientation and dimensions of the order of 0.1 to about 100 &mgr;m can be used as optical conductors and projection displays. The fine structures in the liquid crystals are produced in that the plates bounding and guiding the liquid crystal are provided with micromechanically produced regions having different defined preferred directions. The result is a molecular orientation having a higher refractive index that the surrounding region for guiding and polarizing irradiated light. The orienting layers on the plates bounding the liquid crystal are micromechanically structured in that certain spatial regions are mechanically structured in a uniform direction by a stylus moved by piezoelectric means.

Abstract: A compound of formula in which R1 and R2 each independently represent and alkyl or alkenyl group in which one or more hydrogen atoms is optionaly substituted by fluorine, chlorine, or cyano; and in which optionally one or more non-adjacent methylene groups are optionaly replaced by —O—, —COO— or —OOC—; Z1 to Z4 each independently represent a single bond, —CH2CH2—, —CH2O—, —OCH2—, —C≡C—, —(CH2)4—, —(CH2)3O—, —CH═CH—CH2O—, OCH2—, —CH═CH—, —CH═CH—(CH2)2— or —(CH2)2—CH═CH—, with the proviso firstly that the oxygen atom is not linked directly with the chiral dioxane ring and secondly Z2 and Z3 may also represent —COO— or —OOC—; R* and S* signify that the denoted carbon have the (R) or (S) configuration respectively or the optical antipode thereof; and one of A, B and