72 results about "Chiral nematic liquid crystal" patented technology

The present invention provides a laminated retardation optical element that never lowers contrast and thus never degrades display performance even when placed between a liquid crystal cell and a lambda/4 retardation film. In a liquid crystal display 90, a laminated retardation optical element 10 is placed between a polarizer 102A on the incident side and a liquid crystal cell 104, and a lambda/4 retardation film 102C is placed between a polarizer 102B on the emergent side and the liquid crystal cell 104. The laminated retardation optical element 10 comprises: a lambda/4 retardation layer 14 having the function of bringing, to light that passes through this retardation layer, a phase difference corresponding to a quarter of the wavelength of the light; and a C plate-type retardation layer 16 that acts as a negative C plate. The lambda/4 retardation layer 14 and the C plate-type retardation layer 16 are laminated to a transparent substrate 12 in the order mentioned, and are optically bonded to each other. The lambda/4 retardation layer 14 comprises as its main component a horizontally-aligned, cross-linked nematic liquid crystal, while the C plate-type retardation layer 16 comprises as its main component a cross-linked chiral nematic liquid crystal (a cross-linked nematic liquid crystal and a cross-linked chiral agent) or cross-linked discotic liquid crystal.

The present invention provides a bi-stable chiral nematic liquid crystal display and a driving method for the same. Each pixel of the liquid crystal display includes at least a transistor as a switch element to switch a column voltage to the pixel and a capacitor for storing a voltage of the pixel. The method for driving the bi-stable chiral nematic liquid crystal display is to divide each frame to be updated into a plurality of sub-frames. During a period of each sub-frame, the bi-stable chiral nematic liquid crystal is driven to a corresponding state in accordance with a respective driving condition.

The invention belongs to the field of application of liquid crystal materials and provides a method for utilizing polymer stable liquid crystal material to prepare a light brightness enhancement film. The method comprises the following steps of: mixing nematic liquid crystals, chiral compounds, ultraviolet polymerizable liquid crystal monomers, ultraviolet polymerizable siloxane and photoinitiators uniformly according to a certain mass proportion, injecting the mixture into pretreated film materials combined by PSLC substrate, carrying out diffusion from the high-concentration substrate to the low-concentration substrate by the chiral compounds, generating chiral nematic liquid crystals with continuous and different screw pitches, carrying out ultraviolet radiation on the film material, leading the ultraviolet polymerizable liquid crystal monomer molecules to occur polymerization reaction, forming a high-molecular network, leading the planar texture of the liquid crystal molecules to be stabilized and finally obtaining the PSLC material with wide wave reflection characteristics. The film material can reflect circularly polarized light with the reflection wavelength of 300 to 1500nm and the range of the reflected wave width can be precisely controlled. According to the differences of the reflection wavebands, the film material can be applied to the field of light brightness enhancement films and infrared ultraviolet light screen films of liquid crystal displays and the like.

This invention generally relates to a liquid crystal device, and more particularly to such a device in the form of a liquid crystal cell such as for a display device, and further relates to a display device having the liquid crystal device, an optical waveguide device comprising the liquid crystal device, a Variable Optical Attenuator comprising the liquid crystal device, an optical switch comprising the liquid crystal device, a method of controlling transmission of polarised light, and to a further liquid crystal device. A liquid crystal device for controlling transmission of polarised light, comprising: chiral nematic liquid crystal having a helical arrangement of liquid crystal molecules in the absence of an electric field; and at least two electrodes for applying an electric field having a component normal to the helical axis of the chiral nematic liquid crystal, wherein the chiral nematic liquid crystal has negative dielectric anisotropy.

The invention provides a liquid crystal display having high reliability, which is excellent in terms of optical characteristics, heat resistance, and shock resistance, wherein a liquid crystal display consisting of a cholesteric liquid crystal, a chiral nematic liquid crystal or a liquid crystal 1 layer, being a combination thereof, which is roughly pillar-like and polygonal in section or has a roughly pillar-like form enclosed by a closed curve, and divided by said polymer network into areas whose minimum diameter measured by vernier calipers is 5 mum and whose maximum diameter measured by vernier calipers is 100 mum, is obtained by polymer networks 4 formed by polymerization of monomer, so that sufficient reflection can be obtained from the liquid crystal 1 without being optical scattering. Although the perpendicular array of the helical axes of liquid crystal 1 is slightly disordered by a polymer network 4 with respect to the plane of a pair of ITO 2a, 2b and substrates 3a,3b, wherein since almost all light entering from the substrata 3a side is reflected backwards (substrate 3a side) by Bragg's reflection, it is possible to decrease the visual angle dependency in comparison with a prior art liquid crystal display not containing any polymer constituents, and networks 4 which have been greatly established form intensive pillars (macromolcular resin walls), thereby improving the shock resistance properties.

A color liquid crystal display device includes a pair of oppositely disposed substrates each of which is provided with an electrode and has been subjected to homeotropic alignment treatment, and chiral nematic liquid crystal disposed between the pair of oppositely disposed substrates. The chiral nematic liquid crystal is capable of causing birefringence leading to a change in brightness and a change in hue depending on a voltage applied between the electrodes. The liquid crystal is twistedly aligned under electric field application to change a twisted angle, so that a fluctuation in birefringence with temperature is compensated.

A liquid crystal material for a display device includes a first chiral nematic liquid crystal component and a second component that exhibits no liquid crystalline phase at any temperature. The second component is present in an amount effective to reduce the bulk viscosity of the liquid crystal material by at least about 26 % at room temperature or is present in an amount of at least about 5 % by weight based upon the total weight of the liquid crystal material. The liquid crystal material may have a positive dielectric anisotropy. The second component may have a molecular weight not exceeding 205 grams/mole. Embodiments relate to a display device comprising the present material. Another aspect includes a method of increasing the switching speed in a display that employs the present material.

A liquid crystal display apparatus which have a circular polarizer and a liquid crystal display in a stack. The liquid crystal display has a chilral nematic liquid crystal layer between substrates, and on the mutually opposite sides of the substrates, electrodes and aligning layers are formed. The liquid crystal switches between a planar alignment state and a focal-conic alignment state depending on the voltage applied thereto through the electrodes. In a planar state, light reflected by the electrodes is absorbed by the circular polarizer, and a black display is made. In a focal-conic state, light reflected by the electrodes passes through the circular polarizer, and a white display is made. The liquid crystal is driven by a chain of voltage pulses including a reset step of resetting the liquid crystal to a homeotropic state, a selection step of selecting the alignment state of the liquid crystal under zero-volt application and an evolution step of causing the liquid crystal to evolve to the selected alignment state.

The present invention relates to a bistable polymer dispersed liquid crystal display comprising a support, at least one patterned first conductor layer having thereon at least one dried imaging layer comprising a substantial monolayer of isolated domains of liquid crystal material dispersed in a continuous polymer matrix, wherein said dried imaging layer further comprises at least one absorber colorant, and wherein said isolated domains have a size distribution such that the coefficient of variation (cv) is less than 0.35.

The objective of the present invention is to provide a liquid crystal display device for displaying colors by transmission and reflection modes and a method for producing such devices, whereby the additive color mixing can be used, the structure is simplified, the driving-voltage is lower, the contrast is higher, the response speed is higher, and the screen can be larger. This objective can be achieved by a method including the following steps: mixing 0.001 to 20 wt % of dichromatic melanotic pigment into chiral nematic liquid crystal mixed with chiral dopant; preparing a mixture of the liquid crystal and prepolymer to be polymerized into transparent polymeric solid; inserting the mixture into the space between two conductive substrates, wherein at least one of which is transparent; and irradiating ultra-violet light or neighboring short-wavelength light onto the mixture. This process creates an accumulation of small packets composed of the liquid crystal packed with a thin film of the transparent polymeric solid within a light-controlling layer between the two conductive substrates. When no voltage is applied, the pigment molecules absorb light because they are distributed within the space with their longitudinal axis randomly directed. When a voltage is applied, elongated liquid crystal molecules are oriented perpendicular to the substrates, and the pigment molecules are also oriented in a similar manner. In this state, the black color of the pigment molecules does not appear, so that light is allowed to pass therethrough.

The present invention is based on a chiral nematic liquid crystal composition which shows cholesteric liquid crystal phase and be able to reflect light in visible region selectively, comprising:

• • a nematic liquid crystal material;
  • a first chiral material with shift direction of selective reflection wavelength toward long wavelength direction depending on temperature;
  • and a second chiral material with shift direction of selective reflection wavelength toward short wavelength direction depending on temperature;
  • wherein at least one chiral material between the first chiral material and the second chiral material comprises two or more chiral compounds, and relates to a preparation method of the above chiral nematic liquid crystal composition and a (layered-type) liquid crystal display using the same.

Disclosed is a reflective color liquid crystal display element having a four layered structure. The display element specifically comprises the following layers from an observation side: a single layer of a liquid crystal cell which comprises a chiral nematic liquid crystal composition for the blue color reflection; a single layer of a liquid crystal cell which comprises a chiral nematic liquid crystal composition for the green color reflection; and two layers of liquid crystal cells each of which comprises a chiral nematic liquid crystal composition for the red color reflection. In some of the embodiments, a phase difference plate is inserted between the two liquid crystal cells for the red color reflection.

A normally white supertwist nematic liquid crystal display of reflective type is provided. This display comprises a reflector, a layer of chiral nematic liquid crystal having a front aligning surface facing a light source and a rear aligning surface facing the reflector, and a front polarizer. The nematic liquid crystal has an optical retardation (Deltand) of the layer and a distribution of directors, wherein the chiral nematic liquid crystal has a twist angle (Phi) between an alignment direction of the director at the front aligning surface and an alignment direction of the director at the rear aligning surface. The front polarizer is disposed between the layer of chiral nematic liquid crystal and the light source. The front polarizer has a transmission axis forming an angle (alpha) with the alignment direction of the director at the front aligning surface of the chiral nematic liquid crystal layer. The optical retardation (Deltand) and the angle (alpha) are defined by the following formulas: alpha((Phi)=sign(Phi).(47.0-0.4936|Phi|+2.6786x10<-3>.Phi<2>)±5, deg, and Deltand(Phi)=-11.674+0.1915.|Phi|-9.8393x10<-4>.Phi<2>1.6667x10<-6>.|Phi|<3>±0.05, mum.

On substrates 2a, 2b of a chiral nematic liquid crystal optical element 1, transparent electrodes 3a, 3b and electrical insulation layers 4a, 4b are formed, and further, resin layers 5a, 5b having a pencil hardness of "B" or less are formed on the electrical insulation layers by a spin coating method so as to be in contact with a liquid crystal layer 7. When the surface hardness of the resin layers is to be measured, a glass substrate on which a resin layer is formed by screen-printing is prepared as a test piece, and the test piece is fitted to a pencil-scratching tester. The surface hardness is measured by scratching the test piece with two kinds of testing pencil selected from testing pencils having 17 grades of density.