Abstract: Method and apparatus for providing gray level addressing for passive liquid crystal display (LCD) panels having overlapping row and column electrodes defining pixels are disclosed. Depending upon whether the rows are being addressed by "standard" or "Swift" addressing, the signals for applying to the column electrodes are determined by different calculations, in all of which modes the amplitudes of the column signals are related to the gray level desired to be displayed by the individual pixels. For a split interval system, column signals of appropriate amplitude and polarity are applied during different subintervals of a characteristic time interval of the display panel depending upon the method of addressing the rows. In the full interval mode, the column signals applied over a full time interval are based on the desired gray level of all the pixels in the column, adjusted to provide the proper rms voltage across all the pixels so that they display the desired gray levels.

Abstract: An addressing method and apparatus addresses faster responding liquid crystal display panels (LCDs) so that video rate, high information content LCDs having time constants on the order of 50 ms or less are perceived as having improved contrast by limiting peak voltage levels across the pixels. In a preferred embodiment, a first set of LCD electrodes is continuously driven with signals each comprising a train of pulses that are periodic in time, have a common period T, are independent of the information to be displayed, and are preferably orthonormal. Plural column signals are generated from the collective information states of the pixels defined by the overlap with a second electrode pattern. Each column signal is proportional to the sum, obtained by considering each pixel in the column, of the exclusive- or (XOR) products of the logic level of the amplitude of each row signal times the logic level of the information state of the pixel corresponding to that row.

Abstract: A non-emissive flat panel display, such as an LCD having a plurality of pixels defined by the overlapping areas of row and column electrodes, is provided with a novel mask arrangement to block light from leaking through the interpixel spaces or gaps without electrically shorting the electrodes. The light-blocking mask is split into two parts, with one part deposited on each substrate to block the light from being transmitted through the inter-electrode gaps on the opposite substrate to improve the contrast ratio of the display.

Abstract: A process and apparatus for the production of an orientation layer on a plane surface of a plate, and a liquid crystal substrate plate produced thereby. By the process of evaporation from a source, orientation layers are deposited on the plane surfaces of a plurality of liquid crystal substrate plates used for application in liquid crystal displays. To obtain a uniform orientation of the optic axis of the liquid crystal with regard to the azimuthal alignment by means of the preferred direction caused by the orientation layer on the surface, the plates are moved in a direction crosswise to the evaporation direction during the evaporation process. The field of the particle stream emanating from the source is limited by an aperture in an aperture screen which is introduced between the source and the plates. The plates pass completely through the particle stream during the course of the evaporation operation. The finished plates include an approximately 5 nm thick orientation layer.

Abstract: A liquid crystal display based on the bistability effect, wherein the distance between the support plates is smaller than 10 .mu.m and the total twist of the liquid crystal is between 180.degree. and 360.degree., preferably about 270.degree.. Over the entire viewing area of the display, randomly distributed spacers are provided. Because of these measures, the range of the bistable action is so narrowed that the display can be driven with operating voltages outside this range, using conventional multiplexing techniques. A high degree of multiplexing with short switching times and excellent contrast is obtained. The range of viewing angles is very large and independent of the direction of illumination.

Abstract: A liquid crystal display based on the bistability effect, wherein the distance between the support plates is smaller than 10 .mu.m and the total twist of the liquid crystal is between 180.degree. and 360.degree., preferably about 270.degree.. Over the entire viewing area of the display, randomly distributed spacers are provided. Because of these measures, the range of the bistable action is so narrowed that the display can be driven with operating voltages outside this range, using conventional multiplexing techniques. A high degree of multiplexing with short switching times and excellent contrast is obtained. The range of viewing angles is very large and independent of the direction of illumination.

Abstract: An addressing method for a multiplexable, bistable liquid crystal display wherein a first driving voltage which is larger than a first limiting voltage is applied to the selected display elements and a second driving voltage which is smaller than a second limiting voltage is applied to the non-selected display elements. For the first driving voltage only a first optical state is stable, and for the second driving voltage only a second optical state is stable. All the display elements are simultaneously switched on the display by means of a single writing voltage pulse. By this means a high-contrast, constant and immediate display is achieved over the entire active area. Row-at-a-time writing is also possible. Moreover, a liquid crystal display is introduced which is based upon the bistability effect and which employs a guest-host liquid crystal containing a chiral additive. The layer thickness of the liquid crystal is less than 10 .mu.

Abstract: A liquid crystal mixture intended for electrooptical displays having no polarizers, consisting of:a nematic liquid crystal as the host phase;an optically active additive to give the host phase a cholesteric structure; andat least one pleochroic anthraquinone dye as the guest phase dissolved in the host phase, said anthraquinone dye having the formula: ##STR1## wherein R.sup.2, R.sup.3 and R.sup.4 are the same or different substituents and are selected from the group consisting of hydrogen, hydroxyl, amino, and short-chain N-monoalkylamino substituents; Y represents halogen, alkyl or alkoxy groups each with 1-16 carbon atoms, amino, alkylamino groups with 1-16 carbon atoms in the alkyl portion, nitro, or hydroxyl group; X represents halogen, amino or the group R.sup.5, wherein R.sup.5 is an alkyl group with 1-18 carbon atoms, an alkyl chain with 1-18 carbon atoms that is interrupted with one or two oxy groups or a group having the formula:--(CH.sub.2).sub.p --(O--C.sub.2 H.sub.4).sub.r --O--R.sup.

Abstract: A liquid crystal display is described for displaying dark signs on a light background in accordance with the guest-host principle without polarizers. The display includes parallel plates the insides of which are provided with an orientation layer which produces a homoeotropic orientation in an adjacent liquid crystal mixture. The liquid crystal mixture is formed primarily of a nematic liquid crystal having a high negative dielectric anisotropy and, secondarily, of an optically active substance. The proportion of the optically active substance is smaller than the quantity which would cause a spontaneous formation of a twisted structure in the liquid crystal mixture in the field-free state. The liquid crystal mixture is thus homoeotropically oriented and transparent throughout in the field-free regions, and is planar-cholesteric and absorbing in the activated regions.

Abstract: An electro-optical display for the display of dark symbols against a bright background, wherein except for fine separation lines the front and rear cell plates are almost entirely covered with isolated electrode elements. The regions of overlap between these various front and rear electrode elements define the areas of the selectable display segments. The display employs an electro-optic media requiring no polarizers, for example, cholesteric liquid crystals to which has been added pleochroic dyes, or electrophoretic suspensions. The display device is addressed through the application of appropriate signals to the electrodes so that a vanishingly small potential difference lies across the liquid crystal layer in the region of the selected display segments which remain dark. In all the other regions of the display, however, there exists a potential difference which is larger than the transition voltage of the electro-optical medium, and these regions therefore appear as a bright background.

Abstract: An arrangement for a polychrome display comprises in serial association a light source, a linear polarizing filter, at least one nematic liquid crystal rotating element, and either a passive birefringent retardation plate followed by a further neutral linear polarizing filter or a selective polarizer.

Abstract: A process for the manufacture of an electrooptical display device including a circuit board and a liquid crystal display cell mounted on the circuit board, including forming a circuit board having at least one light conducting region; disposing the liquid crystal display cell adjacent the light conducting region of the circuit board; locating at least one light emitting element in the circuit board for illuminating the light conducting region; and attaching a semi-transparent reflector to the liquid crystal cell; wherein at least part of the circuit board is manufactured by combining a reflecting layer, which is produced by the deposition of a reflective material on a substrate or on one side of a mesh, with a light diffusing substance, by embedding these two materials together in a transparent polyester or epoxy resin.

Abstract: A liquid crystal display, and process of manufacture therefor, emloying an integrated reflector internal to the liquid crystal cell, and consisting of a guest-host liquid crystal layer sandwiched between two cell plates and located between front and rear electrodes. At least the front electrode is composed of segments and parts of the reflector and/or rear electrode that lie opposite the conduction paths leading to these segments are at an electrical potential whose difference from the potential of the conduction paths is smaller than the threshold voltage of the liquid crystal layer used.

Abstract: In a cholesteric guest-host liquid crystal composition having a positive dielectric anisotropy and consisting of a nematic host component with a dye incorporated as a guest component therein and an optically active (cholesteric) component, the improvement consisting of a substantially stable and water insoluble azo dye guest component having a pleochroic ratio a.sub.1 /a.sub.2 of at least 6.5 and an absorption maximum in the range of from 350 to 700 nm, said azo dye being a compound of the formula (1)X -- A -- N .dbd. N -- B -- Y (I)wherein A is selected from the group consisting of 1,4-phenylene, 2-hydroxy-1,4-naphthylene and 2-hydroxy-8-amino-1,4-naphthylene; B is selected from the group consisting of 1,4-phenylene, 1,5-naphthylene and 5-substituted benzothiazo-(1,3)-2-yl; X is selected from the group consisting of nitro, nitrile, dimethylamino, di(hydroxyethyl)-amino, phenyl and straight chain C.sub.1 -C.sub.

Abstract: An electrooptic display device which can be operated either in the transmission or reflection mode. The display device consists of a liquid crystal display cell and a semitransparent reflector located in or on a circuit board having a light emitting element disposed therein and characterized by at least one light conducting region.

Abstract: A novel light scattering reflector and methods of making and using it are disclosed. The reflector, which can advantageously be used in conjunction with liquid crystal displays, includes a layer carrier formed of glass or rigid PVC foil. The layer carrier is roughened by sandblasting, impressing with a grooved die, or by other techniques to provide an irregular surface. A reflective metal coating is subsequently evaporated onto the roughened surface to complete the reflector structure. Auxiliary materials may also be coated onto the layer carrier to improve the characteristics of the device.

Abstract: An improved apparatus is disclosed for producing and modulating monochromatic light and is characterized by a bright, high contrast display surface. The apparatus includes a linear polarizer positioned between a light source and a liquid crystal cell, and utilizes, as a reflector, a substance with a helical structure. A circular polarizer is positioned between the liquid crystal cell and the reflector.

Abstract: A liquid crystal display device for the colored display of information with a reflector and a twisted nematic liquid crystal cell placed between a linear and a selective polarizer is disclosed. The selective polarizer is disposed in front of the twisted nematic liquid crystal cell and the linear polarizer is disposed between the twisted nematic liquid crystal cell and the reflector.

Abstract: An improved liquid crystal display apparatus is disclosed which is characterized by an especially bright and uniform readout surface. The display apparatus includes only a single polarizer placed between the light source and the liquid crystal cell, and the liquid crystal molecules are rotated through 45.degree. about an axis normal to the surface of the liquid crystal cell.