Rolic Ag

Hoffmann-la Roche Inc.

Niopic Moscow Research and Production Association

Jurg Funfschilling

Martin Schadt

Richard Buchecker

Klaus Schmitt

Hubert Seiberle

Alois Villiger

Stephen Kelly

Nikolai Malimonenko

Mikhail I Barnik

Vladimir G Chigrinov

Rolf-Peter Herr

Nina I Chernova

Marina V Loseva

Leonid A Beresnev

Xin Hua Chen

Yury P Panarin

Seraey V Belyaev

Sandra Lupfert

Willy Friedrichsen

Martin Ruetschi

Sergey V Belyaev

Fvgeniy P Pozhidaev

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.

Driving method for a distorted helix-ferroelectric liquid crystal cell

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 that

Ferroelectric liquid crystal cell with a saturated switching angle or

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. Starting from the SBFLC display cell disclosed in EP-A 0 405 346, the display cell according to the invention is distinguished in that its liquid crystal layer contains polymerized molecules and is formed, by treatment with light and an alternating electric field, in such a way that it has two equivalent, bistable switching states.

Bistable ferroelectric liquid crystal cell

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..

Optical component with plural orientation layers on the same substrate

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.

Imidazothiazoles

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.

Distorted helix ferroelectric liquid crystal cell

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.

Ferroelectric liquid crystal display in which the switching angle does

Objects of this invention are cyclopentyl compounds of the general formula ##STR1## wherein k signifies a whole number of 4 to 18;

Cyclopentyl derivatives

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.

DHF ferroelectric liquid crystalline display, switching or image

Colors are generated in the display device by guiding light through three serially-arranged, electrically controlled color filters. Each filer attenuates one of three colors. The color filters incorporate two cholesteric filters, two .lambda./4 plates, and one electrically switchable liquid crystal display.

Device for displaying colors produced by controllable cholesteric color

Optically active compounds of the formula ##STR1## wherein n stands for the number 0 or 1; Z.sup.1 is a single covalent bond or --CH.sub.2 CH.sub.2 --; Z.sup.2 is a single covalent bond, --CH.sub.2 CH.sub.2 --, --CH.sub.2 O--, --OCH.sub.2 --, --COO-- or --OOC--; rings A.sup.1 and A.sup.2 each independently represent trans-1,4-cyclohexylene or optionally halogen-, cyano- and/or methyl-substituted 1,4-phenylene in which optionally 1 CH group or 2 CH groups is/are replaced by nitrogen; R.sup.2 is a group R.sup.4 or a group of the formula ##STR2## R.sup.4 is cyano, halogen, --OCY.sup.1 F.sub.2, --CY.sup.1 F.sub.2 or an alkyl group in which optionally one &gt;CH--CH&lt; is replaced by &gt;C.dbd.C&lt; and/or optionally one methylene group or two non-adjacent methylene groups is/are replaced by --O--, --COO-- and/or --OOC-- and/or optionally one methylene group is replaced by --CHY.sup.2 --; Y.sup.1 is hydrogen or fluorine; Y.sup.2 is halogen, cyano or methyl; R.sup.1 and R.sup.3 denote alkyl in which optionally one &gt;CH--CH&lt; is replaced by &gt;C.dbd.C&lt; and/or optionally one methylene group or two non-adjacent methylene groups is/are replaced by --O-- and/or optionally one or more hydrogen atoms is/are replaced by fluorine; and (S*) and (R*) denote the relative configurations of the chiral carbon atoms, as well as liquid crystalline mixtures which contain such compounds and their use for optical and electro-optic purposes.

Optically active methyl dioxanes

Compounds of the formula ##STR1## wherein R.sup.1 signifies a straight-chain alkyl group with 7 to 9 carbon atoms; and R.sup.2 represents a straight-chain alkyl group with 6 to 11 carbon atoms. their manufacture, liquid crystalline mixtures which contain these compounds and their use for electro-optical purposes.

Phenylpyridine derivatives and liquid crystalline mixtures containing

An optical frequency conversion element has a wave-guiding layer which consists of a .chi..sup.(2) -active ferroelectric liquid crystal. The monomeric or polymeric liquid crystal material has a periodic structure which permits the so-called quasi phase matching of a guided laser beam. The period length of the structure is equal to twice the coherence length l.sub.c =.pi./.DELTA..beta. of the material, whereby .DELTA..beta.=.beta..sub.o (2.omega.)-2.beta..sub.o (.omega.), with .omega.=angular frequency of the fundamental wave, 0=zero-order mode and .beta.=propagation constant of the mode.

Quasi-phased matched optical waveguide frequency conversion element

A bistable ferroelectric liquid crystal display cell utilizes two plates, a chiral ferroelectric smectic liquid crystal sandwiched between the plates, and an electrode for applying an electrical field to the plates. The chiral ferroelectric smectic liquid crystal has a structure which is influenced by the action of an electric field so that its optical anisotropy changes. By using a first polarizer connected to one of the plates and a second polarizer connected to the other plate, the unique bistable ferroelectric display produces dark parallel stripes when the polarizers are in a cross position relative to each other.

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Basel, Switzerland

Jurg Funfschilling