Hoechst Aktiengesellschaft

Merck Patent Gesellschaft MIT Beschrankter Haftung

Siemens Aktiengesellschaft

Kent State University

Gerd Heppke

Feodor Oestreicher

Detlef Lotzsch

Christian Bahr

Rainer Wingen

Dieter Ohlendorf

Gunter Scherowsky

Barbara Hornung

Liang-Chy Chien

Claus Escher

Hans-Rolf Dubal

Ingrid Muller

Antal Jakli

Lutz Lehmann

Michael Morr

Harald Bock

Gunther Scherowsky

Hans Sawade

Wolfgang Helfrich

Annerose Gobl-Wunsch

Alexander Moller

Burkhard Knippenberg

Michael Krumrey

Heinz-Siegfried Kitzerow

Daniel Krüerke

A liquid crystal device comprising tilted smectic phases of banana-shaped liquid crystal molecules is disclosed. A method for fabricating a light modulating device is also disclosed. The method comprises the steps of providing a pair of substrates with a cell gap therebetween and permanently disposing at least one banana-shaped liquid crystal material into said cell gap. The present invention also provides a method of generating an image, comprising providing a pair of substrates with a cell gap therebetween, providing transparent electrodes on each of the substrates adjacent to the cell gap, disposing at least one banana-shaped liquid crystal material into the cell gap; and applying an electric field across the electrodes. The tilted smectic phases of banana-shaped liquid crystal may be in either a racemic or a chiral state. The application of a sufficiently high electric field transitions the banana-shaped liquid crystal material between the racemic and chiral states, and both the racemic and the chiral states are stable in the absence of an electric field.

Electro-optical devices from banana-shaped liquid crystals

Compounds of the formula (I) having side chains with multiple methyl branches

Compounds having side chains with multiple methyl branches and their use

The invention relates to an electro-optically switchable columnar liquid-crystalline system wherein the columns have ferroelectric transverse polarization. The molecules in the columns of electro-optically switchable ferroelectric phases are tilted to or otherwise aligned with the longitudinal axis of the columns in such a manner than the columns are ferroelectrically polarized. The ferroelectric polarization is in a direction transverse to the column axis or has at least one transverse component. The polarization direction need not be the same for all columns of a columnar phase. The transverse polarization of the columns is fully or partially realigned by application of an electrical field to the liquid crystal. The liquid-crystalline system according to the invention can be used to produce electro-optical switching and display devices.

Switchable columnar liquid-crystalline systems

Liquid crystal phases containing at least one optically active compound of the formula I ##STR1## wherein X.sup.1 and X.sup.2 independently of one another are each --CO--O-- or --O--CO--, one of X.sup.1 and X.sup.2 may also be --O--,

Liquid crystal phase

The novel esters of a chiral alcohol and a mesogenic carboxylic acid are characterized by the general formula (I) ##STR1## in which the symbols have the following meanings: n denotes 0 or 1,

Chiral esters of mesogenic carboxylic acids in liquid crystal phases

The chiral smetic liquid-crystalline compounds of the general formula (I)

Chiral smetic liquid crystals and glassy materials containing the same

The twistable liquid crystal phases contain at least two chiral compounds (admixtures), at least one exhibiting helix inversion and at least one other having a high twisting capacity. With the aid of this combination of chiral compounds possessing certain properties, it is possible to effect temperature compensation with a relatively small amount of added admixtures.

Liquid crystal phase containing admixtures which effect temperature

Chiral esters of mesogenic carboxylic acids

Use of compounds or mixtures of compounds which have a chiral, orthogonal, more highly ordered smectic phase in the range of said phase as switching or indicating medium. Compounds which have a chiral, orthogonal, more highly ordered smectic phase, in particular an S.sub.B * or an S.sub.E * phase, can be used in the range of said phase or phases as indicating or switching medium in electro-optical indicating or switching components (devices) which are based on the exploitation of the electroclinic effect.

Use of compounds or mixtures of compounds which have a chiral,

The novel compounds are chiral esters of .alpha.-substituted phenylalkanoic acids and mesogenic hydroxy compounds, the symbols in the general formula (I) ##STR1## being defined as follows: MO=molecular radical of a mesogenic hydroxy compound MOH after removal of one H, the radical MO being expressed by the general formula (II)

Chiral esters of .alpha.-substituted phenylalkanoic acids and mesogenic

The novel compounds are chiral esters formed from .alpha.-substituted carboxylic acids and mesogenic hydroxyl compounds of the general formula (I) ##STR1## in which the symbols have the following meaning: MO=molecular radical of a mesogenic hydroxyl compound MOH after removing an H, the radial MO being expressed by the general formula (II):

Chiral esters formed from .alpha.-substituted carboxylic acids and

The new esters derived from a chiral compound containing two OH groups and at least one mesogenic carboxylic acid which have the general formula (I) ##STR1## in which X.sup.1 =O--H or O--CO--(C.sub.1 to C.sub.12)alkyl and X.sup.2 =O--MC or X.sup.1 and X.sup.2 denote O-MC independently of each other, where MC is the molecular radical of a mesogenic monocarboxylic acid after splitting off an OH group. The esters or esters substituted in the aromatic part of the phenolic part preferably find application as an admixture intwistable liquid crystal phases in which they produce a temperature compensation and a high degree of twisting.

Chiral phenolic esters of mesogenic carboxylic acids and their use as

The circular polarizer comprises a liquid crystal cell, the liquid crystal layer (8) of which is present as a so-called 'blue phase' and can be exposed to a variable electric field. The blue phase is an optically isotropic chiral phase which, like the cholesteric phase, reflects circularly polarized light within a narrow frequency band and accordingly, in this spectral region, transmits only light which is circularly polarized (in the opposite sense). Under the influence of the field, the reflection band changes its position and can be shifted almost continuously from blue to red by means of relatively small voltage changes. The circular polarizer can, by means of simple additional measures, for instance by including a color-neutral circular polarizer, be developed into a color modulator and, in particular, it also makes a multi-colored display of information possible.

Color-selective circular polarizer and its use

An optical system contains a liquid crystal cell (1), to the liquid crystal layer (11) of which an E-field can be applied transversely to the plane of the layer. A light source (3) sends to the liquid crystal cell (1) a beam of rays parallel to the field direction. The liquid crystal is in the form of a chiral, optically isotropic phase ('blue phase'). This phase has a field-dependent optical density for the incident light and is matched to the light wavelength such that no selective reflection takes place. Such a cell is also optically isotropic in the presence of an E-field, switches rapidly and requires no interface orientation. Its preferred fields of use are: intensity modulation of light of a given wavelength, or as a phase grid in a schlieren-optical system, an etalon in a laser, or a light switch.

Blue phase liquid crystal system, method of operation and its use

Liquid crystal phases containing at least one optically active compound of the formula I

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Berlin, Germany

Gerd Heppke