Within Cholesteric Phase Patents (Class 349/175)
  • Publication number: 20040201816
    Abstract: A method and structure for broadening cholesteric liquid crystals spectrum are described. An electrode structure is added on a side of cholesteric liquid crystals, for producing a fringe field which is perpendicular to a screw axis of the cholesteric liquid crystal. Hence, the thread pitches of cholesteric liquid crystals near the electrode structure are lengthened, but the other thread pitches of cholesteric liquid crystals far from the electrode structure remain the same. Besides, light having appropriate wavelength is used to congeal the cholesteric liquid crystals having a polymeric characteristic, so that the cholesteric liquid crystals have varied thread pitches while no voltage is applied to the electrode structure. Therefore, the spectrum of cholesteric liquid crystals and applications thereof are widened.
    Type: Application
    Filed: April 8, 2004
    Publication date: October 14, 2004
    Inventors: Yu-Wen Chen, Chuen-Ru Lee, Szu-Fen Chen, Sheng-Shiung Hou
  • Patent number: 6801263
    Abstract: A liquid crystal display apparatus is provided that includes a liquid crystal display device having two polarizing filter arranged on opposite sides of a light modulating unit. The liquid crystal display apparatus also includes a back light on the back side of the liquid crystal display device, two eye polarizing filters fixedly mounted on the back light, an infrared LED arranged on the front side of the liquid crystal display device for illuminating the light on the head of a viewer, and light receiving devices deposed at a present spacing from the front sides of the two eye polarizing filter unit. Moreover, the liquid crystal display apparatus includes a position control unit for processing and comparing the volumes of the light by the light receiving devices to control the position of the back light in the left-and-right direction.
    Type: Grant
    Filed: December 7, 2001
    Date of Patent: October 5, 2004
    Assignee: Sony Corporation
    Inventors: Seiji Sato, Hidehiko Sekizawa
  • Patent number: 6781666
    Abstract: Disclosed is a liquid crystal display having stacked liquid crystal light modulation layers each containing a liquid crystal compound. At least one of the liquid crystal modulation layers is different from remaining ones in at least one of a dielectric anisotropy, a thickness, a liquid crystal compound contained therein, and a functional layer provided therein so that the drive voltage ranges for the layers are made equal.
    Type: Grant
    Filed: June 2, 2003
    Date of Patent: August 24, 2004
    Assignee: Minolta Co., Ltd.
    Inventors: Nobuyuki Kobayashi, Masako Iwamatsu, Hideaki Ueda
  • Publication number: 20040135960
    Abstract: A display includes a ferroelectric liquid crystal material having an asymmetric polarity response property, a section which applies an image signal to a pixel of the material for every two fields forming one frame, and a controller which reverses the polarity of the signal in one frame period. Particularly, the controller is configured that the polarity of the signal is reversed in a selected one of first and second manners, the first manner initiating a signal amplitude change from a polarity in which a larger response of the material is obtainable, the second manner initiating a signal amplitude change from a polarity in which a smaller response of the material is obtainable, and the selected manner being smaller in the total of brightness deviation generated in a frame immediately after the change for each of predetermined brightness transitions.
    Type: Application
    Filed: January 6, 2004
    Publication date: July 15, 2004
    Applicant: KABUSHIKI KAISHA TOSHIBA
    Inventors: Tatsuo Saishu, Hajime Yamaguchi, Rieko Fukushima, Rei Hasegawa, Kohki Takatoh
  • Patent number: 6757039
    Abstract: This invention relates to paper white cholesteric displays employing a reflective elliptical polarizer. In the reflective mode, the paper white ON state is achieved by a reflective elliptical polarizer in display's planar texture area; and the black OFF state is obtained by cholesteric's depolarization effect and polarizer's filtration effect in display's focal conic texture area. In the transmissive mode, on the other hand, the paper white ON state is created by a back lighting projected onto the focal conic texture area; and the black OFF state is realized in the cholesteric planar texture area. The reflective elliptical polarizer with a broadband reflection and high polarization efficiency delivers a bright neutral white color to both the reflective and transmissive mode cholesteric displays. The reflective elliptical polarizer also provides a solution to the transflective display where the high efficiency front-lit mode and the back-lit mode can be converted automatically.
    Type: Grant
    Filed: June 17, 2002
    Date of Patent: June 29, 2004
    Inventor: Yao-Dong Ma
  • Publication number: 20040119933
    Abstract: A light modulation medium comprises a light modulation element having a pair of substrates and plural light modulation layers arranged between the substrates to form a multilayer structure and made of cholesteric liquid crystal adapted to change the liquid crystal orientation in response to application of a predetermined electric field, in which the ratio of the threshold electric field at which the liquid crystal orientation is moved from a planar state to a focal conic state of a first light modulation layer of the light modulation element to that of a second light modulation layer is not less than 0.3 and the ratio of the dielectric constant in a planar state of liquid crystal orientation of the first light modulation layer to that of the second light modulation layer is not less than 4.
    Type: Application
    Filed: July 8, 2003
    Publication date: June 24, 2004
    Applicant: Fuji Xerox Co., Ltd.
    Inventors: Haruo Harada, Hiroshi Arisawa
  • Patent number: 6753044
    Abstract: Disclosed are novel reflective microflakes for use in making “additive-primary” coloring media having improved reflection characteristics over the red, green and blue super-bright color characteristics, and “super-white” coloring media having Magnesium-Oxide like color characteristics. The coloring media of the present invention provides a palette of colors for imparting color characteristics or forming color images upon surfaces of arbitrary surface geometry. In the preferred embodiments of the invention, the microflakes are made from cholesteric liquid crystal (CLC) material, wherein the pitch of the helices of the liquid crystal molecules in each CLC microflake varies along the thickness dimension (i.e. transverse to the surface) thereof. Depending on the final spiral structure of the materials utilized, the CLC circularly polarizing materials reflect either left-handed or right-handed circularly polarized light.
    Type: Grant
    Filed: July 9, 1997
    Date of Patent: June 22, 2004
    Assignee: Reveo, Inc.
    Inventors: Sadeg M. Faris, Le Li
  • Patent number: 6724459
    Abstract: A reflective liquid crystal display includes upper and lower substrates that are opposite to and are spaced apart from each other; a liquid crystal layer interposed between the upper and lower substrates; a transparent common electrode on the surface of the upper substrate opposite the lower substrate; a cholesteric liquid crystal (CLC) color filter that selectively reflects and transmits light, the CLC color filter formed over the lower substrate; a transparent pixel electrode on the CLC color filter; and a light absorption layer between the lower substrate and the CLC color filter.
    Type: Grant
    Filed: June 29, 2001
    Date of Patent: April 20, 2004
    Assignee: LG. Philips LCD Co., Ltd.
    Inventor: Sunghoe Yoon
  • Patent number: 6693686
    Abstract: A polarizing element 20 includes a cholesteric layer 21 that selectively reflects either one of right-handed and left-handed circularly polarized components of incident light, and an absorptive elliptical polarizing plate 22 that is laminated to the cholesteric layer 21. The polarizing plate 22 transmits elliptically polarized light that contains as its main component the circularly polarized component having the direction of optical rotation that is identical to that of the circularly polarized component selectively reflected by the cholesteric layer 21. In this polarizing element 20, the angle (angle of lamination) which the direction of the major axes of liquid crystalline molecules aligned on the absorptive-elliptical-polarizing-plate-side surface of the cholesteric layer 21, d1, forms with the direction of the major axis of elliptically polarized light produced by the absorptive elliptical polarizing plate 22, d2, falls in a specified angle range centering around 90°.
    Type: Grant
    Filed: July 24, 2002
    Date of Patent: February 17, 2004
    Assignee: Ai Nippon Printing Co., Ltd.
    Inventor: Masanori Umeya
  • Patent number: 6674494
    Abstract: 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.
    Type: Grant
    Filed: May 3, 2001
    Date of Patent: January 6, 2004
    Assignee: OPTREX Corporation
    Inventors: Satoshi Niiyama, Noriko Suehiro
  • Patent number: 6674505
    Abstract: A light-modulating cell and a display device based on a chiral nematic liquid crystal material in which the difference of optical rotation power between the planar nematic state and the focal conic state is used for discriminating between optical states, in particular for chiral nematic liquid crystal material having a pitch length associated with infrared light.
    Type: Grant
    Filed: November 4, 1999
    Date of Patent: January 6, 2004
    Assignee: Koninklijke Philips Electronics N.V.
    Inventors: Peter Van De Witte, Rifat Ata Mustafa Hikmet
  • Patent number: 6674504
    Abstract: A device and method of manufacturing a single layer multi-state ultra-fast cholesteric liquid crystal includes two optically transparent states with a liquid crystal arranged therebetween, and changing the optical states of the liquid crystal ranging from one state to any combination of broadband reflection, tunable narrow band reflection, light scattering, and transparency in accordance with a voltage applied to the device. A surfactant can be added to reduce the response time and a dichroic dye may be added to include the property of light absorption and reduce the bandwidth. The device can provide any and all of the aforementioned optical states for infrared light, visible light, and ultra-violet light. The desired outputs can be formed according to need, so that predetermined optical states can operate with either no voltage or a particular voltage or voltage range.
    Type: Grant
    Filed: October 1, 2001
    Date of Patent: January 6, 2004
    Assignee: Kent Optronics, Inc.
    Inventors: Le Li, Deng-Ke Yang
  • Patent number: 6669999
    Abstract: A method for making broadband cholesteric liquid crystals with improved bandwidth. The method includes the main steps of: (a) preparing a polymerization mixture containing first and second chiral liquid crystals, wherein the first chiral liquid crystal possesses a cholesteric liquid crystal phase and the second chiral liquid crystal possesses a helix-inversion characteristic, and at least one of the first or second chiral liquid crystals contains a polymerizable functional group; and (b) subjecting the polymerization mixture to a polymerization reaction, wherein the polymerization reaction is conducted such that the first chiral liquid crystal will go through a helix-inversion phenomenon. In a preferred embodiment, the second chiral liquid crystal has a temperature-dependent helicity which exhibits a helix inversion characteristic at a helix inversion temperature.
    Type: Grant
    Filed: May 30, 2001
    Date of Patent: December 30, 2003
    Assignee: Industrial Technology Research Institute
    Inventors: Pao-Ju Hsieh, Hui-Lung Kuo
  • Patent number: 6630982
    Abstract: A color tunable pixel (100) includes a cholesteric liquid crystal (110). The helical pitch of the cholesteric liquid crystal (110) is controlled by applying electrical fields (202, 302) of varying strength and/or frequency perpendicular to an initial helical axis (H) of cholesteric liquid crystal (110) in order to shift the hue of light reflected by the cholesteric liquid crystal (110). The reflectivity of the cholesteric liquid crystal (110) may be controlled by applying an electric field (402) perpendicular to the initial helical axis (H) at a frequency at which the cholesteric liquid crystal (110) exhibits a negative dielectric anisotropy. Alternatively the visible light reflectivity may be controlled by applying an electric field to shift the reflectance of the cholesteric liquid crystal (110) into the infrared portion of the spectrum, or in another embodiment by allowing the cholesteric liquid crystal (110) to revert to an ultraviolet reflected state.
    Type: Grant
    Filed: October 18, 2001
    Date of Patent: October 7, 2003
    Assignee: Motorola, Inc.
    Inventor: Zili Li
  • Patent number: 6599442
    Abstract: Helical arrays comprising structurally different chiral non-racemic molecules or molecular entities that control the helical sense of the helical array provide a method for temperature measurement with a unique characteristic in that the temperature dependent chiral biases of the competing structurally different chiral non-racemic entities control the helical sense population since these biases differ in their temperature dependence. By varying the composition of the chiral non-racemic entities, the temperature at which the helical sense population is equal and how the helical sense population varies as a function of temperature can be controlled. In this way, competing structurally different non-racemic chiral groups can be varied in their composition so that a helical array can be formed under their effect and be sensitive to temperature over a wide temperature range.
    Type: Grant
    Filed: February 26, 2001
    Date of Patent: July 29, 2003
    Assignee: Polytechnic University
    Inventor: Mark M. Green
  • Patent number: 6597426
    Abstract: Sheet-like structures obtainable by thermal curing and having a crosslinked cholesteric liquid crystalline ordered structure are suitable, for example, for decorative coatings, for producing security marks, pigmentary particles, polarizers, color filters and IR reflectors.
    Type: Grant
    Filed: March 31, 1999
    Date of Patent: July 22, 2003
    Assignee: BASF Aktiengesellschaft
    Inventors: Karl Siemensmeyer, Peter Schuhmacher, Markus Bröcher, Christian Kuckertz, Werner Mormann
  • Patent number: 6573971
    Abstract: A bistable twisted nematic LCD cell is presented. The cell includes front and rear polarizes, substrates and a liquid crystal layer between the substrates. Rubbing directions are arranged to give an initial twist angle of the liquid crystal, arranged such that the cell does not make a configuration with an initial twist angle of 180° and wherein an initial twist angle is not a multiple of 90°, and a twist angle is in the range of 30-80°, with a retardation in the range of 0.33-0.44 &mgr;m.
    Type: Grant
    Filed: February 3, 2000
    Date of Patent: June 3, 2003
    Assignee: Varintelligent (BVI) Limited
    Inventors: Steven Wai Leung Yeung, Siu Kwan Kwok, Celene Chang
  • Patent number: 6549254
    Abstract: An optical device (20) is provided using at least one film (23) of cholesteric liquid crystal to reflect at least one predetermined wavelength band from an incident light. This device is characterized in that a non zero birefringence gradient is present in a portion or the entire thickness of said film. The gradient may be obtained in particular by superposing layers (24a-24j) having increasing or decreasing respective birefringence coefficients. The birefringence gradient has the effect of removing the lateral bands of the reflection spectrum, hence making the color of the reflected light more brilliant and more saturated. The effect is particularly advantageous in the case of the color red, for which the lateral band located on the yellow side is perceived strongly by the human eye.
    Type: Grant
    Filed: August 3, 2000
    Date of Patent: April 15, 2003
    Assignee: Asulab S.A.
    Inventors: Joachim Grupp, Peter Kipfer, Toralf Scharf, Christian Bohley, Rolf Klappert, Hans Peter Herzig
  • Patent number: 6537624
    Abstract: A light-diffusible liquid crystalline film having a fixed cholesteric or chiral smectic C orientation in which the helical axis direction is not uniformly parallel to the film thickness direction, as well as a liquid crystalline film having a fixed cholesteric or chiral smectic C orientation in which the helical axis direction is not uniformly parallel to the film thickness direction nor is the helix pitch uniformly equal in the film thickness direction, are provided.
    Type: Grant
    Filed: June 21, 2000
    Date of Patent: March 25, 2003
    Assignee: Nippon Mitsubishi Oil Corporation
    Inventors: Shinichiro Suzuki, Suzushi Nishimura, Shinichi Komatsu
  • Patent number: 6466297
    Abstract: The invention relates to a method of preparing a broadband reflective polarizer comprising the blending a first mixture A comprising at least one achiral polymerizable mesogenic compound with a second mixture B comprising at least one chiral polymerizable mesogenic compound; and coating a layer of the blended mixture onto a first substrate and aligning the chiral mesogenic material in a planar orientation so that the axis of the molecular helix extends transversely to the layer.
    Type: Grant
    Filed: July 3, 2000
    Date of Patent: October 15, 2002
    Assignee: Merck Patent Geselleschaft mit Beschrankter Haftung
    Inventors: Mark Goulding, David Coates, John Patrick, Mark Verrall, John Argent
  • Patent number: 6462805
    Abstract: Disclosed are various reverse-mode direct-view liquid crystal displays employing a liquid crystal having a characteristic wavelength in the non-visible spectrum, including reflective, transmissive and reflective-transmissive mode displays. In accordance with the principles disclosed, a direct-view liquid crystal display (LCD) includes a front substantially transparent substrate, a rear substrate, and a controllable cholesteric liquid crystal (CLC) disposed between the front and rear substrates and having a characteristic wavelength to reflect non-visible spectrum; the portions of the controllable CLC can selectively exhibit a planar state or a focal-conic state, the portions of the CLC in the planar state appearing dark, and the portions of the CLC in the focal-conic state appearing bright, to an observer of the LCD.
    Type: Grant
    Filed: June 4, 2001
    Date of Patent: October 8, 2002
    Assignee: Display Research, Inc.
    Inventors: Bao-Gang Wu, Jianan Hou, Jianmi Gao, Yong-Jing Wang, Shushan Li, Rui Hai Sun, Gang Chen
  • Patent number: 6421107
    Abstract: The invention relates to a process of preparing a multilayer cholesteric film comprising two or more layers of polymerized cholesteric liquid crystal (CLC) material with planar orientation, with the cholesteric helix axis oriented substantially perpendicular to the plane of the layer, wherein that the cholesteric helical pitch of adjacent layers is varied by controlled migration of a non-polymerized chiral material between the layers, to a multilayer cholesteric film obtainable by such a process, and to the use of the process and a multilayer cholesteric film thereby prepared in optical elements such as polarizers, compensators, alignment layers, color filters or holographic elements, in cosmetics and liquid crystal pigments, for decorative and security applications.
    Type: Grant
    Filed: July 3, 2000
    Date of Patent: July 16, 2002
    Assignee: Merck Patent Gesellaschaft
    Inventors: Simon Greenfield, Alison Linda May
  • Patent number: 6417828
    Abstract: An active matrix-type liquid crystal device is constituted by a pair of substrates, a chiral smectic liquid crystal composition disposed between the pair of substrates so as to form a plurality of pixels, and a plurality of active elements provided to the pixels, respectively, for driving the liquid crystal device in a matrix driving scheme. The chiral smectic liquid crystal composition may preferably comprise at least two specific fluorine-containing mesomorphic compounds and assume two stable states between which a threshold voltage for switching from one of the two stable states to the other stable state is different from a threshold voltage for switching from the other stable state to said one of the two stable states and liquid crystal molecules of the liquid crystal composition change their alignment states so as to provide a halftone state depending on a voltage applied to the chiral smectic liquid crystal.
    Type: Grant
    Filed: February 17, 2000
    Date of Patent: July 9, 2002
    Assignee: Canon Kabushiki Kaisha
    Inventors: Koichi Sato, Mineto Yagyu, Yukio Hanyu, Masahiro Terada, Koji Noguchi, Kouki Nukanobu
  • Patent number: 6417902
    Abstract: The invention relates to a process of preparing a multilayer cholesteric film comprising two or more layers of polymerized cholesteric liquid crystal (CLC) material with planar orientation, with the cholesteric helix axis oriented substantially perpendicular to the plane of the layer, wherein during preparation of the single layers the migration of unpolymerized material between adjacent layers is minimized, to a multilayer cholesteric film obtainable by such a process, and to the use of the process and a multilayer cholesteric film thereby prepared in optical elements such as polarizers, compensators, alignment layers, color filters or holographic elements, in cosmetics and liquid crystal pigments, for decorative and security applications.
    Type: Grant
    Filed: July 3, 2000
    Date of Patent: July 9, 2002
    Assignee: Merck Patent Gesellschaft
    Inventors: Simon Greenfield, Alison Linda May
  • Patent number: 6369868
    Abstract: A light controlling film is described comprising a polymerized polymer network of a crosslinked high molecular weight polymeric material and a low molecular weight cholesteric liquid crystal (CLC) material, wherein the high molecular weight and the low molecular weight form a material having cholesteric liquid crystal (CLC) order such that the film is a reflective circular polarizer whose bandwidth is controllable by an electric field impressed in the film.
    Type: Grant
    Filed: June 5, 1998
    Date of Patent: April 9, 2002
    Assignee: Reveo, Inc.
    Inventors: Bunsen Fan, Jian-feng Li, Le Li, Sadeg Faris
  • Patent number: 6351299
    Abstract: A liquid crystal display device is disclosed, comprising a cholesteric liquid crystal layer which has an intrinsic helical pitch of approximately twice as large as a thickness of the liquid crystal layer and also has a bistable character capable of switching by an application of voltage, and further provided with at least one birefringent medium layer between a polarizer and a substrate. This construction of the liquid crystal display device results in a reduction of birefringent effects, whereby achieving a high contrast, satisfactory color purity, and other display characteristics such as a higher duty ratio operation and faster time response, suitable for displaying a large volume of information data.
    Type: Grant
    Filed: April 11, 1997
    Date of Patent: February 26, 2002
    Assignee: Ricoh Company, Ltd.
    Inventors: Yasuyuki Takiguchi, Hiroyuki Takahashi, Akihiko Kanemoto
  • Patent number: 6348961
    Abstract: A reflective type liquid crystal display which has a liquid crystal composition exhibiting a cholesteric phase in a room temperature and a columnar structure between substrates with ITO electrodes thereon. The liquid crystal composition is a chiral nematic liquid crystal composition which is produced by adding a chiral agent at a ratio within a range from 10 wt % to 45 wt % to nematic liquid crystal which contains a nematic liquid crystal component with a polar group at not less than 25 wt % and of which transition temperature to isotropic phase is within a range from 70° C. to 150° C. The anisotropy of refractive index of the liquid crystal composition is 0.10 to 0.22, and the anisotropy of dielectric constant is 5 to 30.
    Type: Grant
    Filed: August 9, 1999
    Date of Patent: February 19, 2002
    Assignee: Minolta Co., Ltd.
    Inventors: Masako Iwamatsu, Nobuyuki Kobayashi, Hideaki Ueda
  • Patent number: 6346974
    Abstract: A retardation film type guest host liquid crystal display is arranged to reduce coloring in dark representation and to be energy-effective. The liquid crystal display includes a liquid crystal layer containing a given amount of dichroic dye and having a twist alignment, a reflective plate, and a phase plate located between the liquid crystal layer and the reflective plate. The phase plate has a slow axis set at 45 degrees against the alignment direction of the liquid crystal and a retardation set at a half of a phase difference between an ordinary ray before reflection by said reflective plate and an extraordinary ray after reflection.
    Type: Grant
    Filed: November 1, 1999
    Date of Patent: February 12, 2002
    Assignee: Hitachi, Ltd.
    Inventors: Osamu Itou, Shinichi Komura
  • Patent number: 6344887
    Abstract: This invention is related to a full spectrum reflective or tranmissive black-and-white cholesteric liquid crystal display. The white state is realized by a full gamut of light reflection or transmission in the display's planar texture, and the black state is created by cholesterics' scattering type depolarization effect and polarizer's filtration effect in the display's focal conic texture. It has been discovered that the scattering depolarization effect and multi-filtration process can generate a black dark state, the optical “off” state in focal conic texture of cholesteric liquid crystals. In the dark-and-white cholesterics display can be easily upgraded to a full color display by means of micro-color filter structure in both front and back illuminating systems.
    Type: Grant
    Filed: September 10, 1999
    Date of Patent: February 5, 2002
    Inventors: Yao-Dong Ma, Calvin Ma
  • Publication number: 20020008837
    Abstract: In liquid crystal display element having cholesteric liquid crystal between substrates, being substantially polymer free, integral value in visible wavelength range of {exp−[2(&lgr;−nP)2/&Dgr;n2P2]}R is 40-60% of integral value in visible wavelength range of function f(&lgr;) representing wavelength-light reflectance spectrum in colored state. In liquid crystal display element having liquid crystal composition between substrates, at least one substrate has functional surface contacting liquid crystal composition, the functional layer being capable of adjusting orientated state of liquid crystal molecules close to substrate and different orientated state of liquid crystal molecules remote from substrate. Chiral nematic liquid crystal, of nematic liquid crystal mixture having refractive index anisotropy of 0.2-0.34 and at least one chiral material, exhibits cholesteric phase at room temperature, has phase transition temperature of 60° C.
    Type: Application
    Filed: May 1, 2001
    Publication date: January 24, 2002
    Inventors: Akihito Hisamitsu, Nobuyuki Kobayashi, Masako Iwamatsu, Hideaki Ueda
  • Publication number: 20020003600
    Abstract: A reflective type liquid crystal display which has a liquid crystal composition exhibiting a cholesteric phase in a room temperature and a columnar structure between substrates with ITO electrodes thereon. The liquid crystal composition is a chiral nematic liquid crystal composition which is produced by adding a chiral agent at a ratio within a range from 10 wt % to 45 wt % to nematic liquid crystal which contains a nematic liquid crystal component with a polar group at not less than 25 wt % and of which transition temperature to isotropic phase is within a range from 70° C. to 150° C. The anisotropy of refractive index of the liquid crystal composition is 0.10 to 0.22, and the anisotropy of dielectric constant is 5 to 30.
    Type: Application
    Filed: August 9, 1999
    Publication date: January 10, 2002
    Inventors: MASAKO IWAMATSU, NOBUYUKI KOBAYASHI, HIDEAKI UEDA
  • Patent number: 6307610
    Abstract: A liquid crystal device comprises a liquid crystal cell including a layer of ferroelectric smectic liquid crystal material contained between two walls bearing electrodes and surface treated to give both an alignment and a surface tilt to liquid crystal molecules. The material adopts a C2 rather than a C1 arrangement by arranging the surface pretilt &xgr; and the ratio of azimuthal to zenithal anchoring energies &bgr;/&agr; to give a positive energy difference &Dgr;Ws for the liquid crystal director at the surface in the C1 and C2 states. Additionally the provision of a C2 state may be enhanced by allowing the cell to cool from the isotropic phase to a temperature just below a smectic A to chiral smectic phase, then applying 50 Hz ac voltage in the range typically 0.1 to 5 volts rms. across the liquid crystal layer for about 90 seconds, then allowing the cell to cool to ambient temperature.
    Type: Grant
    Filed: August 4, 1998
    Date of Patent: October 23, 2001
    Assignee: The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland
    Inventor: John C Jones
  • Publication number: 20010005246
    Abstract: A liquid crystal display device is disclosed, comprising a cholesteric liquid crystal layer which has an intrinsic helical pitch of approximately twice as large as a thickness of the liquid crystal layer and also has a bistable character capable of switching by an application of voltage, and further provided with at least one birefringent medium layer between a polarizer and a substrate. This construction of the liquid crystal display device results in a reduction of birefringent effects, whereby achieving a high contrast, satisfactory color purity, and other display characteristics such as a higher duty ratio operation and faster time response, suitable for displaying a large volume of information data.
    Type: Application
    Filed: April 11, 1997
    Publication date: June 28, 2001
    Inventors: YASUYUKI TAKIGUCHI, HIROYUKI TAKAHASHI, AKIHIKO KANEMOTO
  • Patent number: 6252640
    Abstract: The present invention relates to a method for manufacturing a polarization film for a liquid crystal display and, more particularly, to a method for manufacturing a polarization film having improved wide band characteristics and improved reflectivity by binding together plural liquid crystal films having different selective light-reflecting central wavelengths.
    Type: Grant
    Filed: December 4, 1998
    Date of Patent: June 26, 2001
    Assignee: LG Cable & Machinery Ltd.
    Inventors: Sung Tae Kim, Tae Min Kim, Yang Kook Kim, Hee Nam Hwang, In Sun Kim
  • Publication number: 20010003473
    Abstract: Cholesteric liquid crystal films using varying pitch helix structures aligned perpendicular to the surface of the film for broadband reflection and transmission of circularly polarized light distort the light at large viewing angles of incidence due to the elliptical cross section of the CLC helix with the light at large incident angles. By using compensating films of an infrared cholesteric liquid crystal to rotate the major axis of the elliptical light to ±45 degrees and a homeotropic film having elongated molecules with the long axis perpendicular to the surface of the film to convert the elliptically adjusted light from the IR CLC film to circularly polarized light, the distortions at large angles can be eliminated. The compensated light will be circularly polarized for large angles of incidence over a broad band.
    Type: Application
    Filed: May 14, 1999
    Publication date: June 14, 2001
    Inventors: CHRISTINA G. GALABOVA, LE LI
  • Patent number: 6188462
    Abstract: The present invention is directed to liquid crystal diffraction gratings with electrically controlled periodicity. An electrical field is applied to liquid crystal device wherein the liquid crystals align to form a diffraction grating. The period of the diffraction grating is varied by changing the applied electrical field. The diffraction grating therefore has a period that can be varied by an electrical field.
    Type: Grant
    Filed: September 2, 1998
    Date of Patent: February 13, 2001
    Assignee: Kent State University
    Inventors: Oleg D. Lavrentovich, Darius Subacius
  • Patent number: 6166790
    Abstract: Disclosed are (1) a polarizer having a function of separating incident light into polarized light through reflection and transmission, which has (a) a haze of 10% or less, or (b) a ratio of parallel transmitted light to incident light of 40 to 60%, (c) a ratio of mirror reflected light to the incident light of 25% or more, (d) a ratio of diffusion reflected light to the incident light of 20% or less or (e) a fraction of mirror reflected light to the whole reflected light of 60% or more; (2) an optical element comprising the polarizer, and a 1/4 wavelength formed by one or two or more retardation layers disposed on at least one side thereof; (3) a lighting device comprising a surface light source, and the polarizer or the optical element disposed thereon; and (4) a liquid crystal display comprising the lighting device and a liquid crystal cell arranged on the light outgoing side thereof, with a polarizing plate intervening therebetween.
    Type: Grant
    Filed: October 9, 1998
    Date of Patent: December 26, 2000
    Assignee: Nitto Denko Corporation
    Inventors: Tadayuki Kameyama, Hisashi Mihara, Hironori Motomura, Naoki Takahashi
  • Patent number: 6166799
    Abstract: A liquid crystal element which comprises an oriented liquid crystal polymer and with which a liquid crystal display less apt to have display unevenness in a wide viewing range including the front and slant directions can be fabricated; and an optical element and a polarizing element each containing the liquid crystal element. The liquid crystal element comprises either a layer of an oriented liquid crystal polymer or a substrate and formed thereon the layer of an oriented liquid crystal polymer, wherein the liquid crystal polymer layer has an average in-plane haze of 10% or higher and a dispersion of the in-plane haze H (%) within the range represented by the relationship a-.sqroot.(10a).ltoreq.H.ltoreq.a+.sqroot.(10a) wherein "a" is the average haze (%), or has an average in-plane haze lower than 10% and a dispersion of the in-plane haze H (%) within the range represented by the relationship 0.ltoreq.H.ltoreq.b+.sqroot.(10b) wherein "b" is the average haze (%).
    Type: Grant
    Filed: June 10, 1999
    Date of Patent: December 26, 2000
    Assignee: Nitto Denko Corporation
    Inventors: Tadayuki Kameyama, Hisashi Mihara, Hironori Motomura, Naoki Takahashi
  • Patent number: 6166800
    Abstract: A full-color image capture system includes a color separation element and a single image sensor array. The color separation element can be operated in either a light reflective (mirror) mode in which selected intrinsic colors are reflected onto the image sensor array, or a light transmissive (filter) mode in which selected colors are transmitted to produce subtractive primary color images. The color separation element can be formed of holographic polymer dispersed liquid crystal materials that reflect light of selected intrinsic colors. The color separation element can include three holographic polymer dispersed liquid crystal material layers so that three different intrinsic colors can be selectively reflected or transmitted onto the image sensor to provide a full-color image.
    Type: Grant
    Filed: December 29, 1998
    Date of Patent: December 26, 2000
    Assignee: Xerox Corporation
    Inventors: Louis D. Silverstein, Thomas G. Fiske, Haiji Yuan
  • Patent number: 6151093
    Abstract: A bistable liquid crystal display device includes a liquid crystal material which has a plurality of states, such as a stable state with a twist angle w.sub.0 and first and second metastable states with w.sub.0 180.degree. and w.sub.o -180.degree., respectively, wherein w.sub.0 is a twist angle along a direction of cell thickness of the liquid crystal material at an initial stable state. In order to properly drive the liquid crystal device, a first pulse voltage is applied to induce a transition from the stable state to a homeotropic state for the liquid crystal material, and a second voltage pulse is subsequently applied to relax the liquid crystal material from the homeotropic state selectively to either the first or second metastable state depending on the pulse shape. The liquid crystal material is composed such that a change of unstrained pitch thereof with temperature may suppress the change of switching behaviors with temperature, to thereby improve display characteristics of the liquid crystal device.
    Type: Grant
    Filed: July 27, 1998
    Date of Patent: November 21, 2000
    Assignee: Ricoh Company, Ltd.
    Inventors: Yasuyuki Takiguchi, Hiroyuki Takahashi
  • Patent number: 6144439
    Abstract: A collimating apparatus that reduces ghost images in the field of view of a main image generated. The collimating apparatus includes a meniscus lens having a reflective concave surface; a cholesteric liquid crystal (CLC), aligned on an axis common with the meniscus lens, disposed on the concave side of the meniscus lens, positioned to reflect light onto the concave surface and having a tilt making the normal of the CLC different from the normal of the meniscus lens; and an image source, disposed on the convex side of the meniscus lens and having a tilt corresponding to the tilt of the CLC. The tilted pair of the meniscus and image source direct any ghost images produced by light leaking through the CLC away from the line of sight of an observer of the main image.
    Type: Grant
    Filed: July 29, 1997
    Date of Patent: November 7, 2000
    Assignee: Kaiser Electro-Optics, Inc.
    Inventor: Jerome T. Carollo
  • Patent number: 6133980
    Abstract: Disclosed are liquid crystal (LC) phase-retarders and linear polarizers and methods and apparatus for making the same. The liquid crystal phase-retarder is realized by a liquid crystal film structure having one or more phase retardation regions formed therein. Each phase retardation region has an optical axis specified by the direction and depth of orientation of liquid crystal molecules along the surface of the liquid crystal film structure. The liquid crystal linear polarizer is realized by a liquid crystal film structure having a chiral phase region within which liquid crystal molecules are cholesterically ordered. One or more nematic phase regions are formed along the surface of the liquid crystal film structure within which liquid crystal molecules are oriented along a direction and to a surface depth sufficient to realize one or more phase retardation regions therein having optical axes along the direction of liquid crystal molecule orientation.
    Type: Grant
    Filed: November 4, 1996
    Date of Patent: October 17, 2000
    Assignee: Metrologic Instruments, Inc.
    Inventor: Sadeg M. Faris
  • Patent number: 6088079
    Abstract: A cholesteric liquid crystal layer which is inhibited from appearing to be colored when viewed from slant directions and thus has excellent viewing angle characteristics, while enabling an improvement in the brightness of liquid crystal displays, etc.; and an optical element and an lighting device with each of which liquid crystal displays and the like excellent in brightness and perceptibility can be fabricated. The cholesteric liquid crystal layer (1) has a helical pitch changing in the thickness direction and shows circular dichroism over a wavelength region having a width of at least 50 nm and including a wavelength of 550 nm, wherein the linearly polarized light obtained through a quarter-wavelength plate has a maximum degree of polarization at a wavelength not shorter than 550 nm, or the degree of polarization thereof in a wavelength region on the longer-wavelength side of 550 nm is higher than that in a wavelength region on the shorter-wavelength side of 550 nm.
    Type: Grant
    Filed: February 2, 1999
    Date of Patent: July 11, 2000
    Assignee: Nitto Denko Corporation
    Inventors: Tadayuki Kameyama, Hironori Motomura, Naoki Takahashi
  • Patent number: 6072549
    Abstract: An "intelligent" window combined with an additional structure for further controlling light incident on the "intelligent" window is disclosed.
    Type: Grant
    Filed: March 14, 1998
    Date of Patent: June 6, 2000
    Assignee: Reveo Inc
    Inventors: Sadeg Faris, Le Li
  • Patent number: 6052103
    Abstract: A liquid crystal device comprises plural pixel electrodes arranged in a matrix form, a common electrodes facing the pixel electrodes, a liquid crystal layer sandwiched therebetween, and plural switches to drive the respective pixel electrodes. A reflectivity or transmittance of the liquid crystal varies according to a first state where a direction of a normal to each of the liquid crystal is the same, a second state where the above direction of the normal is at random, and a third state where a spiral structure of the liquid crystal is untied, and has a hysteresis characteristics with respect to an applied voltage including an insensitive voltage region where a reflectivity or transmission state is not determined by the applied voltage. The device has an operation such that the applied voltage is brought into the insensitive voltage region, after a display signal is written into the pixel electrode, to hold the display state.
    Type: Grant
    Filed: September 29, 1997
    Date of Patent: April 18, 2000
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Hisao Fujiwara, Haruhiko Okumura, Hitoshi Kobayashi
  • Patent number: 6020941
    Abstract: A stereographic liquid crystal display (LCD) and various methods of manufacturing and operating such stereographic LCD. In one embodiment, the LCD includes: (1) first and second substrates having a cell wall structure located in an interstice therebetween that defines first and second sets of independent cells in the LCD; (2) a first controllable liquid crystal (CLC) material located in the first plurality of independent cells, the first CLC material selectively exhibiting an "on" state and an "off" state and having a first polarity when in the "on" state; and (3) a second CLC material located in the second plurality of independent cells, the second CLC material selectively exhibiting an "on" state and an "off" state and having a second polarity when in the "on" state.
    Type: Grant
    Filed: February 12, 1998
    Date of Patent: February 1, 2000
    Assignee: Advanced Display Systems, Inc.
    Inventor: Yao-Dong Ma
  • Patent number: 6015507
    Abstract: A liquid crystal element includes a pair of plates at least one of which is transparent, and a composite layer retained between the plates and including a liquid crystal material in a transparent resin substrate.
    Type: Grant
    Filed: November 8, 1995
    Date of Patent: January 18, 2000
    Assignee: Minolta Co., Ltd.
    Inventors: Nobuyuki Kobayashi, Kiyofumi Hashimoto, Takuji Hatano
  • Patent number: 6016177
    Abstract: Disclosed are a method for producing a circularly polarized separated plate which comprises coating an oriented cholesteric liquid crystal polymer layer with a different kind of cholesteric liquid crystal polymer and heat orienting the resulting coated layer, or heat pressing oriented cholesteric liquid crystal polymer layers on each other, or adhering oriented cholesteric liquid crystal polymer layers to each other through a volatile liquid or a volatile liquid in which a cholesteric liquid crystal polymer is dissolved, thereby forming a close contact laminate of two or more cholesteric liquid crystal polymer layers in which an upper layer is different from a lower layer in helical pitch; a circularly polarized separated plate comprising a close contact laminate of two or more cholesteric liquid crystal polymer layers in which an upper layer is different from a lower layer in helical pitch, the laminate having a mixed layer of cholesteric liquid crystal polymers forming the upper and lower layers, which is d
    Type: Grant
    Filed: May 29, 1998
    Date of Patent: January 18, 2000
    Assignee: Nitto Denko Corporation
    Inventors: Hironori Motomura, Tadayuki Kameyama, Naoki Takahashi
  • Patent number: 5999243
    Abstract: A liquid crystal element which comprises an oriented liquid crystal polymer and with which a liquid crystal display less apt to have display unevenness in a wide viewing range including the front and slant directions can be fabricated; and an optical element and a polarizing element each containing the liquid crystal element. The liquid crystal element comprises either a layer of an oriented liquid crystal polymer or a substrate and formed thereon the layer of an oriented liquid crystal polymer, wherein the liquid crystal polymer layer has an average in-plane haze of 10% or higher and a dispersion of the in-plane haze H (%) within the range represented by the relationship a-.sqroot.(10a).ltoreq.H.ltoreq.a+.sqroot.(10a) wherein "a" is the average haze (%), or has an average in-plane haze lower than 10% and a dispersion of the in-plane haze H (%) within the range represented by the relationship 0.ltoreq.H.ltoreq.b+.sqroot.(10b) wherein "b" is the average haze (%).
    Type: Grant
    Filed: October 29, 1998
    Date of Patent: December 7, 1999
    Assignee: Nitto Denko Corporation
    Inventors: Tadayuki Kameyama, Hisashi Mihara, Hironori Motomura, Naoki Takahashi
  • Patent number: RE38500
    Abstract: Disclosed are (1) a polarizer having a function of separating incident light into polarized light through reflection and transmission, which has (a) a haze of 10% or less, or (b) a ratio of parallel transmitted light to incident light of 40 to 60%, (c) a ratio of mirror reflected light to the incident light of 25% or more, (d) a ratio of diffusion reflected light to the incident light of 20% or less or (e) a fraction of mirror reflected light to the whole reflected light of 60% or more; (2) an optical element comprising the polarizer, and a ¼ wavelength formed by one or two or more retardation layers disposed on at least one side thereof; (3) a lighting device comprising a surface light source, and the polarizer or the optical element disposed thereon; and (4) a liquid crystal display comprising the lighting device and a liquid crystal cell arranged on the light outgoing side thereof, with a polarizing plate intervening therebetween.
    Type: Grant
    Filed: May 21, 2002
    Date of Patent: April 20, 2004
    Assignee: Nitto Denko Corporation
    Inventors: Tadayuki Kameyama, Hisashi Mihara, Hironori Motomura, Naoki Takahashi