Abstract: A diamine compound of formula (I) is proposed as well as polymers, copolymers, polyamic acids, polyamic acid esters, or polyimides based on such compound.

Abstract: A diamine compound is proposed as well as polymers, copolymers, polyamic acids, polyamic acid esters, or polyimides based on such compound. The compound is represented by one of the general formulae (Ia) and (Ib). It could be shown that such structures, in particular for a specific choice of the residue B, provide, if e.g. used as orientation layers, a photostable, vertically aligning material with an improved VHR.

Abstract: The present invention relates to a new optical component comprising an anisotropic diffuser (5,10) with patterned anisotropy; and means (9, 11, 14, 16, 17, 20, 21, 30, 32) for providing a colourshift observable upon changing viewing angle (6) and/or changing angle of incident light (2). It also relates to methods for making such an optical component and uses of such optical components as security elements with a very high level of security.

Abstract: A method for manufacturing a structured optical device (1) starts with a substrate (2), on which is coated an alignment layer (3) and a liquid crystal polymer network layer (4). One of these layers can be created as a coating using a conventional technique. The other layer, either in a first step the alignment layer or in a second step the liquid crystal polymer network layer, is jet printed. The invention advantageously enables the making of a patterned liquid crystal polymer network which can be personalized upon manufacturing.

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: The liquid crystal switchable color filter switches between three color bands and is preferably used for time-sequential color devices, as for example projection devices, direct view displays and video cameras. The color filter employs circularly polarizing selective reflection bands of at least four cholesteric filters (89, 91, 93, 95) together with three liquid crystal switches (81, 83, 85) and related retarder layers. Between the first and the second as well as between the third and the fourth cholesteric filter an additional half-wave plate (111, 113) is provided, which makes it possible to use cholesteric filters having all the same handedness. Furthermore, 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 simplifies production and still exhibits excellent properties for the color switch.

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 photoactive side-chain polymer from the class of polyimides, polyamide acids and esters thereof, comprising as a side-chain a dendritic block incorporating photoactive groups at its surface. The dendritic block preferably represents a unit of formulae Ia, Ib or a combination of them, for example formulae Ic, wherein the broken line symbolizes the linkage to the polyimide main chain. The polymer may be used as an orientation layer for liquid crystals and in the construction of unstructured and structured optical elements and multi-layer systems.

Abstract: A compound is of formula (I), in which: A1 to A4, E1 and E2 each independently represent hydrogen or an optionally-substituted hydrocarbon group; B1 and B2 each independently represent a single bond, an oxygen atom or an optionally-substituted hydrocarbon group; MG1 and MG2 each independently represent an optionally-substituted ring system; CG is a divalent or polyvalent chiral group. The optically active compound may be used as a doping agent for liquid crystals for a wide range of applications including solid state cholesteric filters for projection displays, circular polarisers, optical filters, etc.

Abstract: A liquid-crystal cell has a wall able to impart both the preferred tilt and preferred azimuthal alignment to the liquid-crystal molecules in use in the cell. The wall is made by exposing a material on it to oblique radiation which is circularly polarized or unpolarized, wherein multiple local zones of the material are exposed to radiation, the oblique angle of the radiation being uniform within each local zone but different between two or more zones and wherein locally different oblique radiation is applied in one radiation step by interposing a micro element array between the source of the radiation and the material.

Abstract: A liquid crystal electrooptical element is disclosed that comprises a pair of substrates positioned between a pair of polarising plates, electrodes defining pixel areas and alignment layers disposed on the respective opposing inside surfaces of the substrates, and a chiral nematic liquid crystal sandwiched between the pair of surfaces. At least one of the alignment layers may be patterned in such a way that the azimuth or pretilt or both alignment directions are different at the substrate interfaces suppressing the growth of the ground state of the liquid crystal. When an initial electrical pulse is applied, one of the at least two bistable states can be reached, wherein the contrast ratio between the bistable states is two or greater. A device with such features is long-term bistable and does not require electronic refreshing as long as the displayed information is not changed. Therefore, the power consumption of this bistable device is minimal.

Abstract: New photoactive polymers, their use as liquid crystal (LC) orientation layers and their use in the construction of unstructured and structured optical and electro-optical elements and multi-layer systems. The new photoactive polymers are crosslinkable polymers that can be readily cross linked over a relatively short irradiation time.

Abstract: A component has a substrate (1) made of a transparent material, for example glass. On this layer (1), there is a linear polarizer (2) on which there is a layer (3) of a photo-oriented polymer network (PPN)(=LPP) which is oriented in locally varying fashion via its surface which covers the substrate. The layer (3) is adjoined by an anisotropic layer (4) of cross-linked liquid-crystal monomers. This layer (4) then has a molecular arrangement whose orientation is defined by the underlying orientation layer (3). The layer (4) will have been photocross-linked by exposure to a suitable wavelength of light, with the result that the molecular orientation defined by the PPN layer (3) is fixed. The element denoted as a whole by 7, can then be used as an optical component which is protected against forgery, it being possible for the orientation pattern of the liquid-crystal layer or the optical information stored therein to be made visible by means of an external polarizer (5), for example.

Abstract: A photoactive polymer from the class of polyimides, polyamide acids and esters thereof comprises as a side-chain a photocrosslinkable group of the general formula (I) wherein the broken line indicates the point of linkage to the polyimide main chain and wherein: B is a straight-chain or branched alkyl residue which is optionally substituted, wherein one or more non-adjacent CH2 groups may independently be replaced by a group Q; D represents an oxygen atom or —NR1— wherein R1 represents a hydrogen atom or lower alkyl; and S3 represents a spacer unit. The polymers may be used as orientation layers for liquid crystals and in the construction of unstructured and structured optical elements and multi-layer systems.

Abstract: In order to provide comprehensive and multi-purpose security, an optical security device is provided that comprises a substrate and at least a first optically structured layer. The optical security device may provide first, second and third optical inspection levels, including a first inspection level where an optical effect can be discerned with the naked eye, a second level in which an object can be discerned with the aid of an optical inspection tool, and a third level in which an encrypted object can be discerned with a decrypting optical inspection tool. The first layer may be constructed as a retarder plate of LCP material, having an array of elemental areas with different predetermined orientations.

Abstract: A color switch is provided for selectively switching between color bands for use, for example, in projection optics and direct view optics. The color switch has fewer and thinner layers than in the prior art, but exhibits equal or better color purity and light efficiency. The color switch or filter includes a first filter section for selectively blocking green light and including a cholesteric filter, a quarter wave plate and a liquid crystal switch. The color filter has a second filter section for selectively blocking blue and/or red light including a stack of retarder elements and liquid crystal switches, preferably Deformed Helical Ferroelectric (DHF) switches. The parameters of the filter are determined by an optimization process including minimizing a cost function (G) with respect to the parameters of the second filter section. A polarizing element may be positioned in front of the stack and may be of a type which does not absorb radiation.

Abstract: An optical component contains two or more hidden images for authentication and antiforgery purposes. The images are successively revealed and concealed when the optical component is held between two polarisers and one of them is rotated. The optical component comprises one or more optical retarder(s) in which the images are embedded in separate adjacent stripes or areas, each image being associated with a different mode of interaction with polarised light. Instead of two polarisers, one will suffice if the component is mounted on a reflector.

Abstract: Compounds for use in the preparation of polymerizable liquid crystalline mixtures, liquid crystalline polymers and optical devices prepared from such mixtures and polymers. The compounds include novel compounds comprising an organosiloxane portion and a portion having a structure that is compatible with a mesogenic molecular architecture.

Abstract: Compounds of formula I: wherein the variables are defined as explained in the disclosure. The invention also provides liquid crystalline mixtures and optical or electro-optical devices including compounds of formula (I).

Abstract: In one embodiment, the invention relates to compounds of the formula (I) wherein G1 and G2 independently represent a polymerisable mesogenic residue, X and Sp are as defined herein and M represents an achiral group of formula (II) as defined herein. The compounds of the invention may, for example, be useful as curable liquid crystals and for preparing liquid crystal films.