Abstract: A liquid crystalline compounds:

Abstract: Liquid crystal compounds of formula (I) are described, where formula (I) is given as R1—A—(X)m—(B)n—R2 where A is selected from naphthyl, fluorinated naphthyl, brominated naphthyl, B is selected from phenyl, methylated phenyl, brominated phenyl, fluorinated phenyl, thiophene, pyrimidine and pyridine. R1 and R2 are independently selected from alkyl, alkoxy, akynyl, thioalkyl, Br, CN, SCN, NCS, perfluoroalkyl, perfluoroalkoxy and hydrogen, X is selected from C≡C, COO and C≡C, m is 0 or 1, n is 0 or 1 where m is 1 and n is 0 where m is 0; provided that where A is naphthyl, n is 1 and m is 0 then B is selected from methylated phenyl, brominated phenyl, thiophene, pyrimidine and pyridine; and further provided that where A is naphthyl, X is C≡C, m is 1 and n is 1, then B is selected from thiophene, pyrimidine and pyridine.

Abstract: A surface mode liquid crystal device is made by forming a cell containing a mixture of a liquid crystal and a pre-polymer. An electric field is applied across the cell to arrange the liquid crystal in a predetermined surface mode state, such as the V state in the case of a pi-cell configuration. The liquid crystal is held in this state by the field while the pre-polymer is polymerized or cross-linked, for instance by ultraviolet irradiation. The electric field is then removed. The polymer stabilizes the predetermined surface mode state, for instance preventing relaxation of the V state to twist or splay state in the pi-cell configuration.

Abstract: A ferroelectric liquid crystal device includes a layer of ferroelectric liquid crystal material contained between a pair of substrates, a first plurality of electrodes and a second plurality of electrodes defining a plurality of addressable liquid crystal pixels. A driving arrangement is provided for applying a first signal (Strobe) in succession to the first plurality of electrodes and for applying a plurality of second signals (Data) simultaneously to the second plurality of electrodes. The plurality of second signals are arranged to include non-rectangular wave signals which have a lower harmonic content than a rectangular wave. Non-uniform heating of the device as a result of the application of the second signals (Data) is reduced with consequent improvement in device performance.

Abstract: An optical element includes a liquid crystal layer; and at least one alignment layer in contact with the liquid crystal layer, the at least one alignment layer being formed from a mixture including a first reactive mesogen and a second reactive mesogen. Each of the first and second reactive mesogens have at least one polymerizable functional group, and a number of polymerizable functional groups of the second reactive mesogen is smaller than that of the first reactive mesogen. A ratio of the second reactive mesogen to the first reactive mesogen in the mixture is determined so as to provide a predetermined pretilt angle with liquid crystal molecules in the liquid crystal layer.

Abstract: A ferro-electric liquid crystal cell is addressed by row and column electrodes forming an x,y matrix of display elements. A strobe waveform is applied to each row in sequence while appropriate data waveforms are applied to all the column electrodes. At each display element the material receives an addressing waveform to switch it to one of its two switched states depending upon the polarity of the addressing waveform. The switching characteristics of ferro-electric materials depend upon the shape of the addressing waveform. Two different shapes of addressing waveforms are used to produce two different and separated switching characteristics (FIG. 3). Al least one switching characteristic curve may exhibit a minimum response time at one voltage value, and the display is operated at voltages above this. The data waveforms are alternating positive and negative pulses of period 2ts. The strobe waveform has a zero for one time period ts followed by a unipolar voltage pulse of duration greater than ts, e.g. 1.

Abstract: A ferroelectric liquid crystal cell is controlled by applying a strobe pulse and a data pulse to the cell, the magnitude of the data pulse being modulated in order to control the resultant pulse applied to the cell. The resultant pulse includes a pre-pulse on one polarity and a main pulse of the opposite polarity. When applied to a liquid crystal cell of stepped thickness, the application of data pulses of different magnitudes switches regions of different thicknesses of the cell so as to provide grey level capability.

Abstract: An autostereoscopic display of the invention includes: an illumination source for producing light of a first polarization and light of a second polarization different from the first polarization; a spatial light modulator for modulating the light of the first polarization and the light of the second polarization from the illumination source; and an optical system for directing the light of the first polarization to a first viewing region and the light of the second polarization to a second viewing region, wherein the spatial light modulator includes: a first polarization adjusting member for transmitting the light of the first polarization and substantially preventing transmission of the light of the second polarization; a second polarization adjusting member for transmitting the light of the second polarization and substantially preventing transmission of the light of the first polarization; and first and second groups of picture elements optically aligned with the first and second polarization adjusting mem

Abstract: The invention provides a ferroelectric liquid crystal display with uniformly spaced greyscale levels. The invention uses a bistable ferroelectric liquid crystal display formed by a layer of chiral smectic liquid crystal material between two cell walls. The walls carry e.g. line and column electrodes to give an x,y matrix of addressable pixels, and are surface treated to provide bistable operation. Each pixel may be divided into subpixels thereby giving spatial weighting for greyscale. Temporal weighting of greyscale is obtained by switching a pixel to a dark state for time T1 and a light state for time T2. When T1 and T2 are not equal, four different greyscales are obtainable; i.e. dark, dark grey, light grey, and light. The present invention provides a required uniform spacing of greyscale levels by addressing each pixel two or more times in one frame time.

Abstract: R.sub.1 --A--(X).sub.m --(B).sub.n --R.sub.2 (I)R.sub.3 --J--(Y).sub.p --(Z).sub.q --R.sub.4 (II)Liquid crystal compounds of formula (I) are described, where formula (I) is given as R.sub.1 --A--(X).sub.m --(B).sub.n --R.sub.2 where A is selected from nathyl, fluorinated naphthyl, brominated naphthyl, B is selected from phenyl, methylated phenyl, brominated phenyl, fluorinated phenyl, thiophene, pyrimidine and pyridine, R.sub.1 and R.sub.2 are independently selected from alkyl, alkoxy, alkynyl, thioalkyl, Br, CN, SCN, NCS, perfluoroalkyl, perfluoroalkoxy and hydrogen, X is selected from C.tbd.C, COO and C.tbd.C, m is 0 or 1, n is 0 or 1 where m is 1 and n is 0 where m is 0; provided that where A is naphthyl, n is 1 and m is 0 then B is selected from methylated phenyl, brominated phenyl, thiophene, pyrimidine and pyridine; and further provided that where A is naphthyl, X is C.tbd.C, m is 1 and n is 1, then B is selected from thiophene, pyrimidine and pyridine.

Abstract: A liquid crystal display comprises a liquid crystal material layer contained between transparent slides which carry electrodes arranged in lines and columns to form an x, y matrix with x, y intersections. The liquid crystal layer at the intersections are turned on line by line by a blanking voltage, turned off by application of a zero voltage, and held at a threshold voltage at other times. The voltages are applied from a two phase supply in the form of two sinusoidal waves spaced 60.degree. apart in phase. Threshold voltages at an intersection are maintained by applying one of the two waveforms to x electrodes and a zero voltage to y electrodes. A zero voltage at x, y intersections is arranged by applying the other of the two waveforms to both x, y electrodes.

Abstract: It has been found that twisted nematic liquid display devices can have a patchy appearance as a result of two problems concerned with degeneracy of the orientation of the molecules in the "on" and "off" states respectively. In the present invention these two problems are solved together by using as the liquid crystal material a naturally optically active material having a molecular helical pitch not less than twice the spacing between the substrates of the device cell, and(1) by treating and later arranging the surfaces of the substrates so that the molecules in the cell liquid crystal layer all lie generally obliquely to the plane of the substrates in the "off" state, or(2) by treating and later arranging the surfaces of the substrates so that the liquid crystal molecules adjacent to one substrate lie in the plane of the substrate but the molecules adjacent to the other substrate lie oblique to that substrate whereby the molecules in the interior of the layer lie slightly oblique to both substrates.

Abstract: A liquid crystal guest-host display device includes a dye dissolved in the liquid crystal material. The invention is characterized in that the dye comprises three colored dye compounds mixed together to provide gray in the absence of an applied electric field. The compounds may be Sudan Black, Sudan Red and .beta.-carotene. The liquid crystal material preferably includes at least one 4'-alkyl- or -alkoxy-4'-cyanobiphenyl compound.

Abstract: A range of eutectic mixtures containing at least three compounds having the formula ##SPC1##Where X.sup.1 is an alkyl group, an alkoxy group or a substituted phenyl group ##SPC2##Where R is an alkyl or alkoxy group, are described. The eutectic mixtures extend the temperature ranges over which their constituent compounds exhibit liquid crystal properties and are thus useful in liquid crystal devices operating in those temperature ranges.

Abstract: An optical intensity adjustment device for adjusting the intensity of optical radiation incident thereon includes a first transparent conducting electrode, a second transparent conducting electrode, a layer of a twisted nematic liquid crystal material contained between the first electrode and the second electrode, an optical polarisation polariser located adjacent to the first electrode for linearly polarising optical radiation incident on the said layer, via the first electrode, an optical polarisation analyser located adjacent to the second electrode for analysing the plane of polarisation of optical radiation emergent from the said layer, means for applying a voltage between the first electrode and the second electrode and, electrically connected to said means for applying a voltage, photoelectric means for sampling the intensity of optical radiation incident on the device and for allowing the voltage applied between the first electrode and the second electrode to be adjusted in response to a change in the