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: 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 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 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

Abstract: A driving method comprising providing preparatory pulses to each pixel, which establish a predetermined voltage prior to the data pulses. The preparatory pulses may either unload the pixel to a resulting potential of 0 V or load it to a resulting voltage of the same polarity as the charge on the pixel in the subsequent frame time.

Abstract: The commercial production of DHF (Deformed Helix Ferroelectric) cells, in particular DHF color display cells, has scarcely become established to date. This is in particular because the DHF cells required for this purpose and based on the known prior art have short switching times and a good angular range of view but relatively high voltages and currents are required for their operation. Moreover, for the production of a DHF cell, the liquid crystal mixture must additionally be oriented or formatted by means of an electric field. The present invention relates to a ferroelectric display cell which does not have these disadvantages and in particular is distinguished by the fact thatthe display is dark at U=0 and bright at .vertline.U.vertline.>0,the current-voltage hysteresis characteristic has two maxima of equal size,the birefringence .DELTA.n in the field-free state is greater than that in the saturated state andthe saturation voltage is relatively low even with very small spontaneous polarization P.sub.

Abstract: Known liquid crystal cells have a nematic liquid crystal configuration and, in accordance with this configuration, are referred to as TN or STN cells. It is true that such cells are adequate for many applications. However, their image quality is dependent to a very great extent on the user's angle of view. Furthermore, TN and STN cells require a continuously applied signal voltage if it is intended to display or store information on one. Bistable liquid crystal cells having a ferroelectric, chiral smectic liquid crystal layer do not have these disadvantages of nematic display cells. However, the commercial production of such bistable display cells has scarcely become established to date. This is in particular because they are not very suitable for reliably storing information or do not permit absolutely equivalent switching between the two bistable positions of the director. The invention now proposes a novel, bistable liquid crystal cell which avoids precisely these disadvantages.

Abstract: An optical component includes a substrate or cell having two spaced-apart substrates, one or more orientation layers on the substrates and one or more anisotropic layers of cross-linked liquid crystalline monomers or oligomers with locally different orientation of the liquid crystal molecules. The surfaces of the orientation layers adjacent the liquid crystalline layers have orientation patterns with a defined parallel or fan-like line structure in locally limited regions. The average spacing between the lines of the fan-like line structure is not greater than the thickness of the liquid crystal layer and the angle between neighboring lines is not greater than 3.degree..

Abstract: Compounds of the general formula ##STR1## have a pronounced tendency to form liquid crystalline S (smectic) phases. Thus, optically inactive compounds of the formula I also have a tilted smectic phase, in particular an S.sub.C phase, in addition to a nematic phase. In contrast, many optically active compounds of the formula I additionally have, inter alia, a tilted smectic chiral phase, in particular a chiral S.sub.C phase, in addition to a cholesteric phase. The stated compounds are therefore particularly suitable as components and as dopants, respectively, for the preparation of a very wide range of liquid crystalline mixtures. The class of compounds comprising compounds of the general formula I offers a broad range of novel components and mixtures for optimization and modification of liquid crystalline mixtures.

Abstract: A distorted helix ferroelectric liquid crystal cell (DHF) is driven with a capacitance connected in series to the liquid crystal layer. Capacity is effected by either an external device (capacitor) or by incorporation of a insulator (dielectric) in the DHF cell. The value of the series capacity is typically smaller than about twice the capacity of the cell without the series capacitance. The capacitive drive circuit, DHF cell and method for driving the circuit and cell, function to shorten the switching times required by conventional cells.

Abstract: A ferroelectric liquid crystal display comprises two liquid crystal cells disposed one behind the other between two polarizers, one cell having line electrodes and the other having pixel electrodes. The pixel electrodes are driven with image information in synchronism with the line electrodes. The orientation and refractive index of the liquid crystal cells are so chosen that transmission is not substantially altered when the control voltages are reversed. The two displays are so actuated that the switching angle never exceeds .+-.22.5.degree.. The polarity of the voltages is periodically so inverted that on average there is no DC voltage across the cells.

Abstract: Objects of this invention are cyclopentyl compounds of the general formula ##STR1## wherein k signifies a whole number of 4 to 18;n signifies 0 or 1;Y.sup.1, Y.sup.2 signify a single bond, --O--, --COO-- or --OOC--;rings A, B, C each independently signify optionally mono- or difluorinated 1,4-phenylene, pyrimidine-2,5-diyl, pyridine-2,5-diyl, pyrazine-2,5-diyl, naphthalene-2,6-diyl, quinoline-2,6-diyl, thiophene-2,5-diyl, thiazole-2,5-diyl or 1,3,4-thiadiazole-2,5-diyl and ring C also signifies trans-1,4-cyclohexylene or trans-1,3-dioxane-2,5-diyl;Z.sup.1 signifies a single bond, --COO--,--OOC-- or --C.tbd.C--;Z.sup.2 signifies --COO--, --OOC--, --OCH.sub.2 --, --CH.sub.2 O-- or --(CH.sub.2).sub.

Abstract: The commercial production of DHF cells, in particular a colored DHF display cell, has scarcely become established to date. This is because in particular such cells based on the known prior art expediently must possess a liquid crystal layer having a thickness d of about 1.4 to 2.8 .mu.m, which requires an expensive and complex production process. On the basis of the knowledge that the mean value of the refractive index of a DHF display can be described with that of a birefringent plate, it has now been found that the magnitude of the birefringence .DELTA.n changes significantly within a voltage range typical for DHF cells, in particular for DHF displays having a large switching angle .alpha.. The present invention therefore relates to the utilization of this second effect of the voltage dependence of .DELTA.n, with the object of substantially facilitating the production of DHF displays.