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WO1988002128A1 - Procede et affichage couleur a cristaux liquides - Google Patents

Procede et affichage couleur a cristaux liquides Download PDF

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Publication number
WO1988002128A1
WO1988002128A1 PCT/US1986/001863 US8601863W WO8802128A1 WO 1988002128 A1 WO1988002128 A1 WO 1988002128A1 US 8601863 W US8601863 W US 8601863W WO 8802128 A1 WO8802128 A1 WO 8802128A1
Authority
WO
WIPO (PCT)
Prior art keywords
liquid crystal
volumes
crystal material
layer
color
Prior art date
Application number
PCT/US1986/001863
Other languages
English (en)
Inventor
James Lee Fergason
Original Assignee
Manchester R & D Partnership
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Manchester R & D Partnership filed Critical Manchester R & D Partnership
Priority to PCT/US1986/001863 priority Critical patent/WO1988002128A1/fr
Priority to US06/942,548 priority patent/US4878741A/en
Priority to CA000546445A priority patent/CA1291552C/fr
Publication of WO1988002128A1 publication Critical patent/WO1988002128A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/13725—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on guest-host interaction
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
    • C09K19/54—Additives having no specific mesophase characterised by their chemical composition
    • C09K19/542—Macromolecular compounds
    • C09K19/544—Macromolecular compounds as dispersing or encapsulating medium around the liquid crystal
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
    • C09K19/60—Pleochroic dyes
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1334—Constructional arrangements; Manufacturing methods based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
    • G02F1/13475—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells in which at least one liquid crystal cell or layer is doped with a pleochroic dye, e.g. GH-LC cell

Definitions

  • the present invention relates generally, as indicated, to liquid crystal color displays and methods, and, more particularly, to the use of subtractive color principles in a multi-layer and/or multicolor liquid crystal display to obtain selected color outputs that may be used to provide a constant or static output image and/or a dynamic or moving image, for example analogous to that produced by a color television.
  • the invention also relates to the scanning, e.g. in the sense of selectively addressing, of respective multicolor portions of a liquid crystal color display apparatus to enable the multiple coloring of the light output, e.g. like a color television picture tube.
  • Liquid crystal material currently is used in a wide variety of devices, including, for example, optical devices such as visual displays.
  • a property of liquid crystal enabling use in visual displays is the ability to scatter and/or to absorb light when the liquid crystal is in a random alignment (sometimes referred to herein as distorted alignment) and the ability to transmit light when the liquid crystal is in an ordered alignment (sometimes referred to herein as parallel alignment).
  • liquid crystal material examples include electrically responsive liquid crystal material and use thereof are found in the above patent(s) and applications and in U.S. Patent No. 3,322,485.
  • a prescribed input such as temperature or electrical input (e.g. electric field, voltage, frequency), changing the optical characteristics and/or the random or ordered alignment of the liquid crystal material, in response to such prescribed input.
  • liquid crystal materials there are three categories of liquid crystal materials, namely cholesteric, nematic and smectic.
  • the present invention preferably uses nematic liquid crystal material or a combination of nematic and some cholesteric type. More specifically, the liquid crystal material preferably is operationally nematic, i.e. it acts as nematic material and not as the other types. Operationally nematic means that in the absence of external fields structural distortion of the liquid crystal is dominated by the orientation of the liquid crystal at its boundaries rather than by bulk effects, such as very strong twists, as in cholesteric material, or layering, as in smectic material.
  • the operationally nematic material may include nematic and cholesteric liquid crystal materials.
  • operationally nematic liquid crystal with chiral ingredients which induce a tendency to twist but cannot overcome the effects of boundary alignment, still would be operationally nematic.
  • liquid crystal of the invention primarily will be referred to interchangeably and equivalently as nematic or as operationally nematic.
  • nematic liquid crystal material is known to be reversible, but cholesteric material ordinarily is not reversible.
  • liquid crystal material is anisotropic both optically (birefringence) and, for example in the case of nematic material, electri ⁇ cally.
  • the optical anisotropy is manifest by the scattering or absorption, especially when pleochroic dye is in solution with the liquid crystal material, of light when the liquid crystal material is in random alignment, and the transmission of light, especially in a particular direction related to an axis of the liquid crystal structure, through the liquid crystal material (and pleochroic dye, if used) when it is in ordered alignment.
  • the electrical anisotropy may be a relationship between the dielectric constant or dielec ⁇ tric coefficient with respect to the alignment of the liquid crystal material and also may be electrical frequency dependent.
  • the preferred liquid crystal material should have a positive dielectric anisotropy; or, as is described below, the liquid crystal may have both positive and negative dielectric anisotropy, e.g. as a function of frequency.
  • Pleochroic dye also has been used in the past in a mixture with operationally nematic liquid crystal contained in plural volumes in a containment or support medium. Examples are given in several of the applicant's above-identified patent(s) and applications.
  • liquid crystal material In the past, displays using liquid crystal material have had to be relatively small in size for a variety of reasons.
  • Using applicant's invention of providing plural volumes of liquid crystal material in a support or containment medium relatively large- and small-size displays can be made and operated successfully.
  • the volumes may be discrete ones, may be interconnected with one or more other volumes, or may include both discrete and interconnected ones.
  • use of operationally nematic liquid crystal material enables operational response as a function of electrical input and also enables relatively expeditious and efficient opera ⁇ tion, for example in response to the application or removal of an electric field.
  • encap ⁇ sulated liquid crystal material, volumes of liquid crystal material in a support or containment medium, etc. means liquid crystal material in capsules, cells or the like formed in or included in a containment medium.
  • the capsules or cells may be discrete, i.e. not fluidically connected to any others, or may be fluidically interconnected with one or more capsules or cells.
  • Such liquid crystal material and containment medium may form an emulsion, preferably a stable one, that is able to set or to cure to a relatively stable structure in which the plural capsules, cells or volumes in the structure contain liquid crystal material and preferably also pleochroic dye.
  • the containment medium is formed of a latex or latex type material, for example as is d ⁇ sclosed in copending U.S. patent application Serial No. 591,433, filed March 20, 1984, the entire disclosure of which is incorporated by reference.
  • the containment medium is polyvinyl alcohol. Epoxy is another example of a containment medium useful in the invention. Other containment media that cause operation generally along the lines described in further detail below also may be used.
  • the invention relates to the producing of a colored output, preferably a multicolored output, by a liquid crystal device that includes pleochroic dye.
  • the liquid crystal device is in the form of a liquid crystal color display that includes at least two different groups of volumes of dyed liquid crystal (for example, operationally nematic liquid crystal and pleochroic dye), the volumes of one group being fluidically and/or chemically separated from the volumes of the other group to isolate the respective dyed liquid crystal of each group from that of the other(s), and the dyed liquid crystal of each group preferably including pleochroic dye of a different respective color.
  • dyed liquid crystal for example, operationally nematic liquid crystal and pleochroic dye
  • the groups of volumes of dyed liquid crystal material may be in separate respective layers of plural volumes (hereinafter referred to as liquid crystal color layers) or the volumes of two or more groups may be mixed substantially homogeneously while maintaining the respective dyed liquid crystal materials isolated from the other differently dyed liquid crystal material.
  • Such mixed volumes embodiment is referred to below as the distributed volumes or distributed volumes layer embodiment whether the volumes are mixed substantially or less than substantially homogeneously.
  • the volumes of dyed liquid crystal material may be in the form of discrete capsules that are isolated totally from other capsules or that are fluidically interconnected to one or more capsules of the same group.
  • the volumes may be in the form of an emulsion of the dyed liquid crystal in a containment medium, in the form of a stable matrix of the dyed liquid crystal in a containment medium, and so on.
  • the layers and/or volumes are arranged in optical serial relation so that incident light transmitted through the display preferably passes through all or at least several of the liquid crystal color layers or differently dyed volumes.
  • Respective color layers or portions thereof or groups of homo ⁇ geneously distributed volumes may be selectively energized to substantial optical transparency or deenergized to color or to filter light transmitted or passing therethrough.
  • Optical operation of the liquid crystal color display follows the principles of subtractive color filter operation, as is described in greater detail below.
  • the dyed liquid crystal material in each volume includes opera ⁇ tionally nematic liquid crystal material and pleochroic dye, which tends to align according to the structure of the liquid crystal material.
  • the structure of operationally nematic liquid crystal material generally tends to assume a straight line configuration
  • the walls defining the volumes in which the liquid crystal material and pleochroic dye is contained tend to distort the natural liquid crystal structure to a curvilinear alignment in the absence of a prescribed input, in the preferred embodiment an electric field.
  • the curvilinearly aligned or distorted liquid crystal structure may be in a direction generally parallel to the wall(s) defining the volume(s) or may be generally normal to such wall(s).
  • Such curvilinear alignment may be referred to as a nematic curvilinearly aligned phase of the liquid crystal or liquid crystal structure and in such phase the liquid crystal material and dye tend to affect incident light. More specifically, the dye tends to color the light or to filter out a particular color from the light.
  • the liquid crystal structure tends to align with respect to the field, and the pleochroic dye structure aligns generally in parallel with the liquid crystal structure; in such parallel aligned or field-on condition or phase the amount of coloring or f iltering of light transmitted through the particular liquid crystal color layer is reduced, preferably is minimized, and most preferably the liquid crystal color layer becomes substantially optically transparent.
  • both groups are off, i.e. in curvilinearly aligned phase such that the dye in both groups affects light serially incident thereon, the transmitted light will be filtered by both groups;
  • one of the groups is on or in parallel aligned mode and the other is curvilinearly aligned, in the former the amount of filtering by dye therein will decrease, and preferably the volumes in such group become clear, and in the latter filtering still would continue; and
  • both groups are on or aligned filtering further decreases and preferably all or nearly all incident light is transmitted.
  • plural electrodes for example of optically transparent electrically conductive material.
  • the electrodes are coupled to an electrical supply that may be manually, automatically, or otherwise controlled to determine whether or not an electric field is to be applied to a liquid crystal color layer or to a portion thereof, the voltage of such field and/or the frequency of the field or applied voltage.
  • the electrical supply or drive may be one that includes multiplex circuitry to scan or to address various portions of a liquid crystal color layer or of multiple liquid crystal color layers and/or of distributed volumes layer(s).
  • a two-electrode arrangement may be used with the liquid crystal itself or the volumes size providing a function to discriminate between different levels of energiza ⁇ tion, e.g. voltage or frequency level.
  • different liquid crystal materials may have different voltage threshold requirements; smaller size capsules require a larger voltage field to switch to aligned state relative to that voltage required to switch larger size capsules; and/or the liquid crystal could have a cross-over dielectric anisotropy changing from positive to negative (or vice versa) as a function of frequency of applied field or voltage.
  • a liquid crystal display generally means a liquid crystal color layer together with the means (preferably electrodes, whether dedicated or shared) for applying a prescribed input (preferably an electric field) to all or portions of the liquid crystal color layer.
  • the assemblage of such liquid crystal displays is referred to as a liquid crystal color display in accordance with the invention.
  • Liquid crystal color display also means groups of such distributed volumes of differently dyed liquid crystal and means (preferably also electrodes) for applying a prescribed input to all or portions of the groups of volumes.
  • a liquid crystal apparatus includes at least first and second liquid crystal displays positioned serially in a common optical path to affect incident light directed thereto, each of the displays including plural volumes of liquid crystal which in the absence of a prescribed input at least one of which scatters or absorbs light and which in the presence of such prescribed input reduces the amount of such scattering or absorption, at least some of the liquid crystal in at least one of the liquid crystal displays having pleochroic dye therein for coloring light passing therethrough.
  • a dynamic light coloring device includes a first layer of liquid crystal material in plural volumes in a containment medium, a second layer of liquid crystal material in plural volumes in a containment medium, at least some of the liquid crystal material in at least one of the layers containing pleochroic dye, and an input device for selectively applying a prescribed input to one or more respective portions of respective layers to determine the coloring or not of light transmitted through such respective portion of a respective layer.
  • each layer includes different colored pleochroic dye; the layers are arranged optically serially; and the liquid crystal color display is operative in an optically subtractive fashion to provide multicolor outputs.
  • a method of coloring light includes directing incident light onto a liquid crystal apparatus having plural layers of liquid crystal material in volumes in a containment medium and at least some of the liquid crystal having pleochroic dye therein, such layers being arranged in optical serial relationship with respect to the path of such incident light, and selectively applying a prescribed input to one or more respective portions of at least one of such layers to alter the optical characteristics thereof.
  • a dynamic color image may be created by directing light into a liquid crystal color display including plural layers of liquid crystal material in plural volumes in a containment medium, a plurality of the layers having different respective color characteristics, the layers being oriented in optical series relationship, and applying an electric input to one or more portions of the respective layers to affect the structure and optical characteristics of the liquid crystal material therein.
  • a cross-linking of materials is employed to establish volume environments for the dyed liquid crystal with secure isolation to minimize the possibility of mixing of one dyed liquid crystal material with another dyed liquid crystal material.
  • the liquid crystal material is capable of discriminating inputs thereto, for example as a function of the frequency or voltage of an applied field; for frequency discrimination a liquid crystal material having different characteristics as a function of frequency, e.g. a cross-over liquid crystal that has positive dielectric anisotropy below a given frequency and negative dielectric anisotropy above such given frequency, may be used; for voltage discrimina ⁇ tion different size volumes of the same liquid crystal may be used, whereby smaller capsules require a larger applied voltage to switch than do larger capsules.
  • an additional aspect relates to an optical device including an assemblage of plural groups of volumes of liquid crystal material, a plurality of the volumes formed of discrete capsules formed by containment medium of cross-linked polymer containing therein the liquid crystal material.
  • Yet a further aspect relates to a method of making liquid crystal capsules comprising the process of mixing a liquid crystal material with a cross-linking producing material to form a first mixture, mixing with the first mixture a polymer containment medium reactable with the cross- linking producing material of the first mixture to undergo cross-linking.
  • an additional aspect relates to an encapsulated opera ⁇ tionally nematic liquid crystal including operationally nematic liquid crystal material in a volume defined by a cross-linked polymer.
  • an optical device including first and second pluralities of volumes of liquid crystal material in a containment medium, each of the first and second pluralities of volumes respectively having a different optical characteristic selectable in response to application and removal of a prescribed input, and each of the first and second pluralities of volumes having a different input responsive character ⁇ istic to discriminate at least one parameter of such prescribed input to effect selection of such respective optical characteristics.
  • a liquid crystal color display includes plural volumes of operationally nematic liquid crystal material in a containment medium and both pleochroic dye in the liquid crystal material and non-pleochroic dye in at least one of the liquid crystal and containment medium to provide a color output in response to a prescribed input.
  • a liquid crystal optical device includes plural groups of volumes of liquid crystal in a containment medium, a plurality of such groups containing in the volumes thereof respective pleochroic dye to color light transmitted therethrough, the volumes being arranged relative to each other in generally optically serial relation to affect color of light transmitted therethrough in a subtractive color operation, and at least one of such groups containing in the volumes thereof black pleochroic dye operative selectively to attenuate light incident thereon.
  • a liquid crystal device includes a first plurality of volumes of a first liquid crystal material and a second plurality of volumes of a second liquid crystal material, the volumes being formed by a containment medium for tending to distort the natural structure of the liquid crystal material in the absence of a prescribed input, the second liquid crystal material having dielectric anisotropy that is frequency dependent, whereby the optical transmission characteristics of the device are a function of the magnitude and frequency of prescribed input applied to said liquid crystal materials.
  • an apparatus for signal dis ⁇ crimination includes plural volumes of liquid crystal material in a contain ⁇ ment medium, the liquid crystal material having a positive dielectric anisotropy in one frequency domain and a negative dielectric anisotropy in a second frequency domain (or vice versa), the effect of which is to discriminate between applied electrical inputs, and an electrical input device for applying such electrical inputs to the liquid crystal material.
  • a liquid crystal device includes plural volumes of liquid crystal material, the liquid crystal material having a natural structure which in the absence of a prescribed input is distorted by a surface defining said volumes, whereby in response to such distortion the volumes of liquid crystal material at least one of scatter or absorb light, and further including an input circuit for supplying as a prescribed input to the volumes of liquid crystal material first and second electrical signals, each having a relatively low and a relatively high frequency component that are respectively additive to apply a resultant field to such volumes of liquid crystal material.
  • at least the liquid crystal material in some of such volumes is cross over liquid crystal material having two different dielectric anisotropy characteristics as a function of frequency of input electrical signal thereto.
  • a liquid crystal color display of the type herein described has pleochroic dye in at least one group or layer of volumes of liquid crystal material, such dye being operative to absorb ultraviolet light.
  • a liquid crystal device uses a phase shifting driving system, with one or more frequencies to achieve particular optical output. Another aspect is to provide a composite layer of two or more liquid crystal compositions that respond differently to a prescribed input.
  • Another aspect is to eliminate parallax in a liquid crystal optical serial device.
  • Another aspect is to maintain adequate resistivity of liquid crystal and a containment medium therefor to obtain adequate electric field across the liquid crystal in response to an applied voltage to affect alignment of the liquid crystal structure.
  • Fig. 1 is a fragmentary enlarged schematic view of a liquid crystal color display according to the invention
  • Fig. 2 is a schematic fragmentary representation of a liquid crystal display, which is a portion of the liquid crystal color display in accordance with the present invention
  • Figs. 3 and 4 are enlarged schematic illustrations of liquid crystal capsules in accordance with the present invention respectively showing curvilinear alignment of the liquid crystal structure in parallel and normal relation to the capsule wall under a no-field or field-off condition;
  • Fig. 5 is an enlarged schematic illustration of a liquid crystal capsule of the type shown in Figs. 3 and 4 but with the capsule in the presence of an electric field and the liquid crystal structure aligned with respect to the field;
  • Fig. 6 is a side elevation or section view of a multi-layer liquid crystal color display in accordance with the preferred embodiment and best mode of the invention;
  • Figs. 7 and 8 are, respectively, lefthand and righthand plan views of the liquid crystal color display of Fig. 6 looking generally in the direction of the arrows 7-7 and 8-8 of Fig. 6;
  • Fig. 9 is a fragmentary enlarged schematic view of an alternate embodiment of liquid crystal color display in accordance with the invention.
  • Fig. 10 is a schematic view of a flat panel multi-color display system, for example useful in a television type display, according to the present invention.
  • Fig. 11 is a schematic illustration of a nematic liquid crystal capsule with cholesteric material additive, which may be used with the several embodiments herein;
  • Fig. 12 is a schematic view of a pair of interconnected capsule volumes useful in the invention.
  • Fig. 13 is a fragmentary enlarged schematic view of a liquid crystal color display using two different color layers and a single pair of shared electrodes;
  • Fig. 14 is a fragmentary enlarged schematic view of a liquid crystal color display similar to that of Fig. 13, but using three different color layers and a pair of shared electrodes and an additional electrode;
  • Fig. 15 is a schematic view of a capsule undergoing formation
  • Fig. 16 is a fragmentary enlarged schematic view of a liquid crystal color display using a homogeneous distribution of differently dyed liquid crystal color capsules
  • Fig. 17 is a fragmentary enlarged schematic view of a liquid crystal color display using true encapsulated dyed liquid crystal and other dyed liquid crystal material in an emulsion matrix;
  • Fig. 18 is a fragmentary enlarged schematic view of a liquid crystal color display using two different size capsules in the respective multiple layers thereof;
  • Fig. 19 is a fragmentary enlarged schematic view of a liquid crystal color display having liquid crystal layers of unequal thickness
  • Fig. 20 is a schematic representation of a frequency discrimi ⁇ nating liquid crystal device according to the invention.
  • Fig. 21 is a schematic representation of a multilayer liquid crystal device capable of multiplex and multi-frequency/phase shifting driving operation
  • Fig. 22 is a schematic representation of the plural crossed electrode strips arrangement in the multilayer liquid crystal device of Fig. 21 omitting the liquid crystal for clarity of illustration;
  • Fig. 23 is a graph of two frequency voltage signal waveforms
  • Figs. 24 and 25 are alternate embodiments of a multilayer liquid crystal device capable of multiplex and multi-frequency/phase shifting driving operation
  • Fig. 26 is a schematic illustration of a liquid crystal display device using multiplex and multi-frequency/phase shifting driving for plural liquid crystal layers together with non-multiplex driving for a third liquid crystal layer;
  • Fig. 27 is a schematic illustration of a liquid crystal display device like that of Fig. 26 but also having a separate pair of electrodes for driving the third liquid crystal layer;
  • Fig. 28 is a schematic circuit diagram of a representative driving circuit
  • Fig. 29 is a schematic illustration of a liquid crystal pixel having four liquid crystal layers, one of which contains black pleochroic dye;
  • Fig. 30 is a schematic illustration of a liquid crystal pixel having four liquid crystal layers, the leading one of which contains a pleochroic dye that absorbs ultraviolet light;
  • Fig. 31 is a schematic illustration of a liquid crystal color display according to a further and alternate embodiment of the invention using both pleochroic dye and non-pleochroic dye in a common liquid color layer.
  • the color display 1 includes three liquid crystal color layers 2, 3, 4 (although more or fewer than three may be used) arranged in optical serial relation relative, for example, to respective optical paths 5, 6 therethrough.
  • the color layers are supported on a common support 7, such as Mylar film, or sheet material, on one side of the color display 1, and a protective material of plastic or other material 8 covers the other side of the color display 1.
  • the color display 1 works in response to the selective application or not of a prescribed input to transmit or not with or without coloring the same incident light 9 to derive output light 10, 10a.
  • the color display 1 employs plural electrodes 11.
  • the prescribed input may be other than an electric field, such as a magnetic field.
  • incident light 9 for example white light
  • incident light 10a may be transmitted as white, colored, or black (no transmission/full absorption) output light 10, 10a.
  • incident light 9 for example white light
  • the liquid crystal in a given color layer is distorted or curvilinearly aligned, as is the pleochroic dye therein, and such layer then acts as a color filter according to the color of the dye therein. Therefore, when multiple layers are in the light absorbing/optical filtering state, such layers filter in a subtractive filtering sense the transmitted light.
  • a given liquid crystal color layer becomes partly or substantially optically transparent and non-filtering (or less filtering) as the liquid crystal structure and dye aligns or tends to align with respect to the field.
  • FIG. 2 an example of a liquid crystal display used according to the invention is represented at 20.
  • the display 20 may be considered the fundamental building block of which the liquid crystal color display described in greater detail below is formed.
  • the display 20 may be generally of the type disclosed in the above-mentioned U.S. Patent No. 4,435,047.
  • the schematically illustrated liquid crystal display 20 includes encapsulated liquid crystal material 21 represented by a single complete capsule 22 and part of another capsule in Fig. 2. Representative individual capsules also are in Figs. 3, 4 and 5. Although the capsules illustrated in the drawings are shown in two dimensions and, therefore, planar form, it will be appreciated that the capsules are three dimensional, most preferably approximately spherical. Also, although the capsules 22 are shown in a single layer between electrodes 11a, lib, trere may be more than one layer of capsules of similarly dyed liquid crystal material in a containment medium between the electrodes and/or there may be plural layers of differently dyed encapsulated liquid crystal between the electrodes, as is described in greater detail below.
  • the capsule 22 (Fig. 2) is shown mounted on a preferably transparent support medium 7, such as Mylar film or sheet material.
  • the liquid crystal display 10 also includes the pair of electrodes 11a, lib for applying an electric field across the liquid crystal material when a switch 23, for example, is closed to energize the electrodes from a conventional voltage source represented at 24.
  • the electrodes 11a, Ub preferably are optically transparent and may be formed of conventional materials, as is well known in the art.
  • the electrode 11a moreover, may be applied to the support 7, for example, a Mylar film support with an electrode material, such as indium tin oxide, coating one surface thereof.
  • the electrode lib may be applied by vacuum deposition, printing, or any other applicable technique that provides the desired optical and electrical characteristics.
  • Exemplary electrode materials include indium tin oxide, tin oxide, and antimony doped tin oxide.
  • the electrodes are relatively thin, for example, about 200 angstroms thick and are adequately transparent so that they preferably do not significantly affect the optics of the liquid crystal display 20.
  • the capsule 22 illustrated in Fig. 2, for example, may be one of many capsules that are discretely formed or, more preferably, that are formed by mixing the liquid crystal material with a so-called encapsulating material or containment medium to form an emulsion, preferably a stable one.
  • the emulsion may be applied to the electrode covered support 7 after which the electrode lib is applied.
  • the support medium 7 and the encapsulating material or containment medium may be the same material, whereby the emulsion, upon curing, provides adequate self-support and containment of a plurality of volumes of liquid crystal material therein, thus forming the capsules 22.
  • the encapsulated liquid crystal material 21 includes liquid crystal 25 contained within the confines or interior volume 26 of a capsule 22.
  • Each capsule 22 may be a discrete one or alternatively the liquid crystal 25 may be contained in a stable emulsion of a containment medium or so-called encapsulating material 27 that tends to form a multitude of capsule-like environments for containing the liquid crystal material.
  • the capsules 22 may be fluidically isolated from each other or may be fluidically inter ⁇ connected with one or more capsules.
  • the encapsulated liquid crystal material 21, including a plurality of volumes 26 of liquid crystal material 25, may be formed of one or both of isolated discrete capsules/volumes and interconnected ones.
  • pleochroic dye represented at 28 in the capsule 22 is included with the liquid crystal 25.
  • the pleochroic dye 28 is represented by "X ⁇ -like markings in the capsule; only several such markings are shown in the various figures, but it will be appreciated that the same represent appropriate amounts of pleochroic dye to effect the desired coloring described in greater detail below.
  • the pleochroic dye has a characteristic of aligning generally in parallel with the liquid crystal structure with which it is mixed.
  • the pleochroic dye 28 when the liquid crystal material is in the curvilinearly aligned phase, distorted from its natural generally linear structural alignment, the pleochroic dye 28 likewise will be in such distorted or curvilinearly aligned structural configuration; and when the liquid crystal structure is aligned with respect to an electric field, the pleochroic dye 28 will align in parallel with the liquid crystal material and, accordingly, with respect to the field. Therefore, in the description herein directed to various alignments or distortions of the liquid crystal structure, such description will be applicable similarly to the pleochroic dye 28.
  • the preferred shape of the capsule 22 is spherical, shapes other than spherical may be employed in the invention.
  • the shape should provide the desired optical and electrical characteristics that will satisfactorily coact with the optical characteristics of the liquid crystal material 25, e.g. index of refraction, and will permit an adequate portion of the electric field to occur across the liquid crystal 25 itself for effecting desired ordered or parallel alignment of the liquid crystal when it is desired to have a field-on condition.
  • the capsule shape also should tend to distort the liquid crystal structure when in a curvilinearly aligned phase or field-off or random alignment condition.
  • a particular advantage to the preferred spherical configuration of the capsule 22 is the distortion it effects on the liquid crystal structure when in a field-off condition.
  • nematic and operationally nematic liquid crystal material have fluid-like properties that facilitate the conformance or the distortion thereof with respect to the shape of the capsule wall, more particularly the wall surface, in the absence of an electric field.
  • nematic or opera ⁇ tionally nematic material will relatively easily change to ordered alignment with respect to the field.
  • Liquid crystal material of a type other than nematic or combi ⁇ nations of various types of liquid crystal material and/or other additives may be used with or substituted for the preferred nematic or operationally nematic liquid crystal as long as the end result is an operationally nematic material.
  • cholesteric and smectic liquid crystal materials gene ⁇ rally are bulk driven, and because it is difficult to break up the bulk structure thereof for conformance to a capsule wall and to the energy considerations in the capsule, such materials are generally not preferred in the invention.
  • the liquid crystal display 20 is intended when in the field-on condition to transmit incident light 9 therethrough without or substantially without affecting the light, and when in a field-off condition also to transmit the incident light 9 or at least to transmit a given color or colors of the incident light while filtering out or absorbing a given color and, therefore, not transmitting such absorbed color.
  • the intensity and color characteristics of the transmitted light output 10 from the liquid crystal display 20 will be a function of the presence or absence of an electric field and the magnitude of any present electric field as well as of the other optical and electrical characteristics of the liquid crystal material, pleochroic dye, containment medium, and electrodes.
  • the liquid crystal material itself have relatively low birefringence and that the index of refraction of the liquid crystal (both the ordinary and extraordinary indices of refraction) is matched or is substantially matched to the index of refraction of the containment medium. Therefore, the volumes of liquid crystal and pleochroic dye will function substantially exclusively as a controllable color filter and/or light transmitting device and not as a light scattering device.
  • FIGs. 3, 4 and 5 a schematic representation of the single capsule 22 (22' in Fig. 4; primed reference numerals in Fig. 4 represent elements that are functionally and structurally generally the same as those identified by unprimed reference numerals in Figs. 3 and 5)
  • the capsules 22 are spherical and have a generally smooth curved interior wall surface 30 defining the boundary for the volume 26.
  • the actual dimensional parameters of the wall surface 30 and of the overall capsule 22 are related to the quantity of liquid crystal 25 contained therein and possibly to other characteristics of the individual liquid crystal material therein.
  • the liquid crystal more particularly the liquid crystal structure, which ordinarily in free form would tend to align in generally linear parallel relation, although perhaps randomly distributed, is distorted to curve in a direction that generally is parallel to a relatively proximate portion of the interior wall surface 30, i.e. the curvilinear aligned phase. Due to such distortion the liquid crystal material may store elastic energy.
  • a layer 31 of liquid crystal molecules whose directional orientation is represented by respective dashed lines 32 is shown in closest proximity to the interior wall surface 30.
  • the directional orientation of the liquid crystal molecules 32 is distorted to curve in the direction that is parallel to a proximate area of the wall surface 30.
  • the directional pattern of the liquid crystal molecules away from the boundary layer 32 within the capsule is represented by 33.
  • the liquid crystal molecules are directionally represented in layers, but it will be appreciated that the molecules themselves are not confined to such layers.
  • the organization in an individual capsule is predetermined by the organization of the structure 32 at the wall and is fixed unless acted on by outside forces, e.g. an electric field. On removal of the electric field the directional orientation would revert back to the original one, such as that shown in Fig. 3.
  • the liquid crystal 25 in the capsule 22 has a discontinuity 35 in the generally spherical orientation thereof due to the inability of the liquid crystal to align uniformly in a manner compatible with parallel alignment with the wall 30 and a requirement for minimum elastic energy.
  • Such discontinuity is in three dimensions and is useful to effect a distorting of the liquid crystal 25 further to decrease the possibility that the liquid crystal 25 would be sensitive to optical polarization direction of incident light.
  • the discontinuity protrusion 35 would tend to cause scattering and absorption within the capsule, and the tangential or parallel alignment of the liquid crystal molecules with respect to portions of the interior wall surface 30 of the capsules both cause scattering and absorption within the capsule 22.
  • the discontinuity will no longer exist so that such discontinuity will have a minimum effect on optical transmission when the encapsulated liquid crystal 21 is in a field-on or aligned condition.
  • encapsulated liquid crystal material 21' which may be substituted in the yarious other embodiments of the invention disclosed herein.
  • the encapsulated liquid crystal material 21' includes operationally nematic liquid crystal material 25' in the volume 26' of a capsule 22' having preferably a generally spherical wall 30'.
  • the material 21' is in field-off condition, and in that condition the structure 33' of the liquid crystal is oriented to be normal or substantially normal to the wall 30' at the interface therewith.
  • the structure 33' is generally oriented in a radial direction with respect to the geometry of the capsule 22'.
  • the orientation of the structure 33' of at least some of the liquid crystal will tend to curve in order to utilize, i.e. to fill, the volume of the capsule 22' with a substantially minimum free energy arrangement of the liquid crystal in the capsule, for example, as is seen in the drawing.
  • Such generally radial or normal (i.e. to the capsule wall 30') alignment of Fig. 4 is believed to occur due to the addition of an additive to the liquid crystal material 25' which reacts with the support medium to form normally oriented steryl or alkyl groups at the inner capsule wall.
  • an additive may be a chrome steryl complex or Werner complex that reacts with the support, containment or encapsulating medium that forms the capsule wall 30 r to form a relatively rigid skin or wall with a steryl group or moiety tending to protrude radially into the liquid crystal material itself.
  • Such protrusion tends to effect the noted radial or normal alignment of the liquid crystal structure.
  • alignment of the liquid crystal material still complies with the above strongly curved distortion of the liquid crystal structure in field-off condition because the directional derivatives taken at right angles to the general molecular direction are non-zero.
  • Nematic type material usually assumes a parallel linear struc ⁇ tural configuration and usually is optical polarization direction sensitive.
  • the material 32, 32' in the encapsulated liquid crystal 21, 21' is distorted or forced to curved form in the full three dimensions of the capsule 22, 22', such nematic liquid crystal material in such capsule takes on an improved characteristic of being insensitive to the direction of optical polarization of incident light.
  • the inventor has discovered, moreover, that when the liquid crystal material 25 in the capsule 22 has pleochroic dye dissolved therein, such dye, which ordinarily also would be expected to have optical polarization sensitivity, no longer is polarization sensitive because the dye tends to follow the same kind of curvature orientation or distortion as that of the individual liquid crystal molecules 32.
  • the encapsulated liquid crystal 21 will transmit substantially all the light incident thereon and will tend not to be visible in the encapsulating medium 27, especially when viewed along the ordinary axis of the liquid crystal, i.e. generally in parallel with the field.
  • the field-off condition when the liquid crystal and pleochroic dye is in distorted alignment or curvilinearly aligned phase, sometimes referred to herein as random alignment, for example as is shown in Figs. 3 or 4, some of the incident light will be absorbed by the dye to affect the color of the light output 10.
  • the index of refraction of the encapsulating medium 27 and the ordinary index of refraction of the liquid crystal 25 should be matched as much as possible when in the field-on or liquid crystal orderly aligned condition to avoid optical distortion due to refraction of incident light passing therethrough.
  • the liquid crystal material is in distorted or random alignment, i.e. there is no field applied, there will be a difference in the indices of refraction at the boundary of the liquid crystal 25 and wall of capsule 22; the extraordinary index of refraction of the liquid crystal usually being greater than the index of refraction of the encap ⁇ sulating medium.
  • Such occurrence of different indices of refraction is known as birefringence.
  • the encapsulating or contain ⁇ ment medium 27 and the support medium 7 have the same index of refraction to appear optically substantially as the same material, thus avoiding a further optical interface.
  • the ordinary index of refraction matches the index of refraction of the medium.
  • the closeness of the index matching will be dependent on the desired degree of contrast and trans ⁇ parency in the device, but the ordinary index of refraction of the liquid crystal and the index of the medium will preferably differ by no more than 0.03, more preferably 0.01, especially 0.001.
  • the tolerated difference will depend upon capsule size.
  • the liquid crystal preferably has low birefringence to obtain optimum colors and minimum scattering.
  • the electric field E shown in Fig. 5 is applied to the liquid crystal 25 in the capsule 22 for the most part rather than being dissipated or dropped substantially in the encapsulating material.
  • the electrical impedance of the encapsulating medium prefer ⁇ ably should in effect be large enough relative to that of the liquid crystal in the encapsulated liquid crystal 21 that a short circuit will not occur exclusively through the wall 34, say from point A via only the wall to point B, bypassing the liquid crystal. Therefore, for example, the effective impedance to induced or displacement current flow through or via only the wall 34 from point A to point B should be greater than the impedance that would be encountered in a path from point A to point A' inside the interior wall surface 30, through the liquid crystal material 25 to point B' still within the volume 26, ultimately to point B again. This condition will assure that there will be a potential difference between point A and point B.
  • the dielectric constant of the material of which the encap ⁇ sulating medium is formed and the dielectric coefficients of the material of which the liquid crystal is comprised, and the effective capacitance values of the capsule wall 34, particularly in a radial direction and of the liquid crystal across which the electric field E is imposed, all should be so related that the wall 34 of the capsule 22 does not substantially drop the magnitude of the applied electric field E.
  • the capacitance dielectric constants (coefficients) of the entire layer of encapsulated liquid crystal material should be substantially the same for the field-on condition.
  • the liquid crystal 25 will have a dielectric constant value that is anisotropic. It is preferable that the dielectric constant of the wall 34 be no lower than the dielectric coefficient of the anisotropic liquid crystal material 25 to help meet the above conditions for optimum operation. It is desirable to have a relatively high positive dielectric anisotropy in order to reduce the voltage requirements for the electric field E.
  • the differential between the dielectric constant (coefficient) for the liquid crystal 25 when no electric field is applied, which should be rather small, and the dielectric constant (coefficient) for the liquid crystal when it is aligned upon appli ⁇ cation of an electric field, which should be relatively large, should be as large as possible.
  • the dielectric constants (coefficients) relationships are discussed in the above patents.
  • the critical relationship of dielectric values and applied electric field should be such that the field applied across the liquid crystal material in the capsule(s) is adequate to cause alignment of the liquid crystal structure with respect to the field and is not short circuited through the encapsulating medium 27 to bypass the liquid crystal.
  • the lower dielectric values of commonly used liquid crystals are, for example, from as low as about 3.5 to as high as about 8.
  • the resistivity of the lqyers of volumes of liquid crystal and contain ⁇ ment medium be adequately high so that in response to an applied voltage across the layer, an electric field that will tend to affect, e.g. to cause alignment, the liquid crystal will be produced. Therefore, it is desirable to purify the containment medium, e.g. the polyvinyl alcohol, to avoid Impurities that could reduce such resistivity.
  • the containment medium e.g. the polyvinyl alcohol
  • the PVA could be purified by Soxlet extraction with methanol for thirty-six hours to remove ionic impurities— articularly those that would be soluble in the liquid crystal.
  • the capsules 22 may be of various sizes. The smaller the size, though, the higher the requirements will be for the electric field to effect alignment of the liquid crystal in the capsule. Preferably, though, the capsules should be of uniform size parameters so that the various character ⁇ istics, such as the optical and electrical characteristics, of an apparatus, such as a display, using the encapsulated liquid crystal will be substantially uniform. Moreover, the capsules 22 should be at least 1 micron in diameter so they appear as discrete capsules or volumes relative to an incident light beam; a smaller diameter would result in the light beam "seeing" the capsules as a continuous homogeneous layer and would not undergo the required isotropic scattering.
  • capsule sizes say from 1-30 microns diameter
  • liquid crystal material examples are in the above con ⁇ currently filed application and are hereby specifically incorporated by reference.
  • Capsule or volumes sizes also may be in a broader range of from about 0.3 to about 100 microns, preferably 0.3 to 30 microns, especially 3 to 15 microns, and most preferably 5 to 15 microns.
  • a preferred liquid crystal material in accordance with the best mode of the invention is one like nematic material 1800 by E. Merck of West Germany. Another preferred liquid crystal is 2359 also by E. Merck.
  • Other examples may be cholesteryl ester combinations, phenyl cyclohexanes, dicyclohexanes, biphenyl and/or biphenyl combinations, and the like.
  • liquid crystal material useful according to the invention are disclosed in Table I (items 1-4) below and include the following four examples, each being a recipe for the respective liquid crystal materials.
  • the so-called 10% material (item 1 in the table) has about 10% 4-cyano substituted materials; the 20% material has about 20% 4-cyano substituted materials, and so on.
  • the 40% material and 40% MOD(ified) material both have 40% 4-cyano substituted materials.
  • Pentylphenylmethoxy Benzoate 54 grams Pentylphenylpentyloxy Benzoate 36 grams Cyanophenylpentyl Benzoate 2.6 grams Cyanophenylheptyl Benzoate 3.9 grams Cyanophenylpentyloxy Benzoate 1.2 grams Cyanophenylheptyloxy Benzoate 1.1 grams Cyanophenyloctyloxy Benzoate 9.94 grams Cyanophenylmethoxy Benzoate 0.35 grams 2. 20% Material
  • the encapsulating medium forming respective capsules 32 should be of a type that is substantially completely unaffected by and does not affect the liquid crystal material.
  • Various resins and/or polymers may be used as the encapsulating medium.
  • a preferred encapsulating medium is polyvinyl alcohol (PVA), which has a good, relatively high, dielectric constant and an index of refraction that is relatively closely matched to that of the preferred liquid crystal material.
  • PVA polyvinyl alcohol
  • An example of preferred PVA is an about 84% hydrolized resin, molecular weight of at least about 1,000.
  • Latex is another preferred encapsulating medium.
  • a method for making emulsified or encapsulated liquid crystals U may include mixing together the containment or encapsulating medium (e.g. water soluble PVA), the liquid crystal material, and perhaps a carrier medium, such as water. Mixing may occur in a variety of mixer devices, such as a blender, a colloid mill, which is most preferred, or the like. What occurs during such mixing is the formation of an emulsion of the ingredients, which subsequently can be dried eliminating the carrier medium, such as water, and satisfactorily curing the encapsulating medium, such as the PVA.
  • the containment or encapsulating medium e.g. water soluble PVA
  • a carrier medium such as water.
  • each capsule 22 of each thusly made encapsulated liquid crystal 21 may not be a perfect sphere, each capsule will be substantially spherical in configuration because a sphere is the lowest free energy state of the individual droplets, globules or capsules of the emulsion, both when ori ⁇ ginally formed and after drying and/or curing.
  • An example of an acid type containment medium useful in the invention is Carbopol (carboxy polymethylene polymer by B. F. Goodrich Chemical Company), or polyacid.
  • Gelvatol PVA materials that may be used include those designated by Monsanto as 20-90; 9000; 20-60; 6000; 3000; and 40-10.
  • a preferred quantity ratio of liquid crystal material to contain ⁇ ment medium is about one part by weight liquid crystal material to about three parts by weight of containment medium.
  • Acceptable encapsulated liquid crystal emulsion operative according to the invention also may be achieved using a quantity ratio of about one part liquid crystal material to about two parts containment medium, e.g., Gelvatol PVA.
  • a 1:1 ratio also will work, generally it will not function quite as well as material in the ratio range of from about 1:2 to about 1:3.
  • the support medium 7 may be of the same or similar material as the encapsulating or containment medium.
  • the support medium 7 may be formed using a molding or casting process.
  • the electrode 11a and liquid crystal material may be applied for support by that medium 7.
  • the electrode lib may be applied, e.g. by printing.
  • an upper support medium or protective cover portion 8 (Fig. 1) may be poured or cast in place to complete enclosing the encapsulated liquid crystal material and the elec ⁇ trodes if desired.
  • the support medium portion 7 may be a substantially transparent plastic-like film, e.g. Mylar, or a plate of glass.
  • support media 7 examples include polyester materials; and polycarbonate material, such as Kodel film. Tedlar film, which is very inert, also may be used if adequate adhesion of the electrode can be accomplished. Such media 7 preferably should be substantially optically transparent.
  • the support medium may be considered as that which supports the liquid crystal material. Accordingly, the support medium may be broadly construed as including or being formed by the containment medium; in such sense the support medium may also be construed as possibly, but not necessarily, including an additional material, e.g. Mylar material 7.
  • the support medium may also be construed as possibly, but not necessarily, including an additional material, e.g. Mylar material 7.
  • there is a liquid crystal material a containment medium which contains the liquid crystal material and provides the surface to effect the desired structure distortion, and a support on which the liquid crystal material and containment medium are supported.
  • a liquid -crystal color display is generally indicated at I in Figs. 1 and 6-8.
  • the display 1 includes three liquid crystal color layers 2, 3, 4, and four electrode layers 44-47 (generally 11 in Fig. 1). Each liquid crystal color layer is sandwiched between a pair of electrode layers.
  • the color layers 2, 3, 4 are arranged in a so-called optical serial relation such that incident light represented by the arrow 9 traveling along an optical path or a light path can travel through all three layers and emerge from the display 1 as transmitted light represented by arrow 10.
  • the display 1 may include more or fewer than the illustrated three color layers 2, 3, 4 arranged in such optical serial relation.
  • liquid crystal color layers may be staggered and one or more of them may be less than fully coextensive over the full input plane 50 of the liquid crystal color display 1, whereby in any given optical path through the display 1, for example the optical path represented by the arrows 9 and 10, only two, in any event less than all, of the liquid crystal color layers would appear in such path.
  • Each of the electrode layers 44, 45, 46 and 47 shown in Fig. 6 is energizable, preferably on a selective basis, to apply an electrical input, preferably an electric field, across a portion of a respective liquid crystal color layer sandwiched therebetween.
  • Each electrode layer such as the layer 44 shown in plan elevation view in Fig. 7, includes a plurality of electrode strips, such as those designated 44a, 44b, etc. (Electrode, electrode layer, and electrode strip may be used interchangeably herein, for example depending on context.)
  • the electrodes in relatively adjacent layers are orthogonally related or are otherwise oriented in non-parallel (not 0° or 180*7 relation.
  • the electrode layer 44 is formed of a plurality of vertical electrode strips 44a, 44b; the electrode layer 45, on the other hand, is formed of a plurality of horizontal electrode strips 45a, 45b, etc., as is illustrated in Fig. 8.
  • the electrode layer 46 is formed of vertical strips like those shown in Fig. 7, and the electrode layer 47 is formed of horizontal electrode strips like those shown in Fig. 8. The arrangement of electrode strips in the electrode layers permits selective application or not of an electric field to respective portions of the liquid crystal color layer between a pair of electrodes.
  • the electrode strips 44a, 45a had applied thereto appropriate electrical ener ⁇ gization, the same would be effective to apply an electric field across a section of the liquid crystal color layer 2 that is essentially aligned and essentially directly between the electrode strips 44a, 45a, the approximate size of the section of liquid crystal color layer 2 being so energized being represented, for example, by the dashed line-bounded rectangle 51 in the upper left corner of the illustration in Fig. 7 and by a portion 52 shown in the upper right hand quadrant of the illustration in Fig. 8. It will be appreciated that by appropriately energizing respective pairs of electrodes in adjacent layers, various portions of a liquid crystal color layer sandwiched therebetween can have an electric field selectively applied thereto.
  • one or both of the electrode layers on opposite sides of a liquid crystal color layer may be formed of a solid electrode, electrode strips or portions arranged in a pattern other than those illustrated in Figs. 6-8, etc., depending on the desired use and operation of the liquid crystal color display 1.
  • each of the liquid crystal color layers 2, 3, 4 is formed of encapsulated liquid crystal material 21 arranged such that a plurality of capsule-like volumes 26 in capsules 22 are provided in each layer.
  • the capsules 22 in the given liquid crystal color layer may be arranged in an orderly stacked layer arrangement, may be close-packed, may be randomly distributed, etc.
  • the thickness of a given layer should be adequate to enable the encapsulated liquid crystal material 21 therein when in a field- off condition to affect light incident thereon and transmitted therethrough and should be adequately thin to permit substantial optical transparency when in a field-on condition.
  • pleochroic dye is contained in the respective encapsulated liquid crystal material 21 in each of the layers 2, 3, 4.
  • the layers 2, 3, 4 may, respectively, contain yellow, cyan, and magenta color pleochroic dye.
  • Other dyes may be used, as well.
  • each liquid crystal color layer contain only a single color dye or a single color mixture of dyes.
  • different portions of respective liquid crystal color layers may contain different respective dyes or mixtures thereof.
  • liquid crystal color display 1 illustrated in Fig. 1 (and similarly shown in Fig. 6) in which the liquid crystal color layer 2 contains yellow pleochroic dye; the liquid crystal color layer 3 contains cyan color pleochroic dye; and the liquid crystal color layer 4 contains magenta color pleochroic dye; by selectively applying or not an electric field to respective portions of respective liquid crystal color layers, a multicolor output of the transmitted light 10 selectively can be achieved.
  • the encapsulated liquid crystal material 21 in the yellow dyed liquid crystal color layer 2 is in the field-on condition, such layer becomes substantially optically trans ⁇ parent and will have minimum affect on the light incident thereon and, accordingly, transmitted therethrough.
  • the liquid crystal material 21 in the color layer 2 when the liquid crystal material 21 in the color layer 2 is in the field-off condition, the light transmitted therethrough will be colored, dyed, or filtered in such a way that it tends to appear yellow. Accordingly, with the liquid crystal material in the color layers 3 and 4 in a field-on condition so that the same is effectively optically transparent, and the liquid crystal material in the yellow color layer 2 in the field-off condition, for white incident light 9, the output light 26 will be yellow in color. It will be appreciated that the pleochroic dyes in the color layers 2, 3, 4 function to absorb specific color or colors of light when in the field-off condition. Accordingly, operation of the liquid crystal color display 1 may be analogized to the operation of negative film used in color photography; and the construction and operation of the display 1 may be similar to the construction and operation of such negative film employed in color photography.
  • Table HI below depicts several possible combinations of field-on and field-off conditions of respective portions of the liquid crystal color layers 2, 3, 4 and as a function of the particular combination of field- on/field-off conditions and white incident light 9, the color of the output light 10.
  • yellow pleochroic dye would be Sudan-I; of cyan would be Indophenol Blue; and of magenta would be D-3 .
  • Other pleochroic dyes also would function according to the invention; an example would be red pleochroic dye Sudan-m.
  • the color of the respective liquid crystal layers 2, 3, 4, is represented.
  • the color of the output light 10 is represented as a function of white input light 9 and the field-off or field-on state of the liquid crystal in a given layer 2, 3, 4 in a serial optical path, such as that represented at 5 or 6, directly through the display 1.
  • the yellow dyed liquid crystal material 21 in a layer 2 proximate the path 5 should be in the field- off condition; that in the layer 3 proximate the path 5 should be in the field- off condition; and that in the layer 4 proximate the path 5 should be in the field-on condition.
  • those colors, as well as others, shown in Table HI, as weU as white and black can be achieved by selectively applying or not an electric field to respective portions of liquid crystal color layers 2, 3, 4.
  • electrodes in electrode layers 45 and 46 of the display 1 are located between the liquid crystal color layers on opposite sides thereof and are of the singular shared type cooperating with each other and respectively with non-shared or dedicated electrodes in the electrode layers 44 and 47 to apply, when necessary, an electric field across respective portions of respective liquid crystal color layers to achieve the desired optical output of the display 1.
  • Electrode circuitry for energizing the respective electrodes is not shown in detail; however, it wiU be appreciated that such circuitry may include an electrical power supply, switching circuitry, and electrical connections to respective electrodes selectively to energize the same to apply an electric field or not to the liquid crystal material between a respective pair of electrodes, as was mentioned earUer.
  • An advantage to the shared electrode configuration of the display 1 in Fig. 1 is the minimizing of the number of electrodes and, therefore, the minimizing of any optical attenuation (ab ⁇ sorption) effected by the electrode(s) on light incident thereon.
  • the electrodes are substantiaHy optically transparent, it is the usual case that the electrode layer wiU not be 100% transmissive.
  • FIG. 9 a modified Hquid crystal color display 1' which uses a separate pair of non-shared or dedicated electrode layers for each liquid crystal layer is illustrated.
  • the display 1' is similar to the display 1 described above with reference to Fig. 1, and, therefore, primed reference numerals designate parts in the display 1' corresponding to similarly identi ⁇ fied parts in the display 1.
  • the display 1' includes a support V. liquid crystal color layers 2', 3', 4', and a protective layer 8'. AdditionaHy, the liquid crystal color display 1' includes an electrode layer 44' between the support 7' and color layer 2' and an electrode layer 47' between the color layer 3' and the protective sheet 8'. However, in contrast to the Hquid crystal color display 1, the color display 1' does not require the sharing of electrodes.
  • the liquid crystal color layers V, 3' there are two electrode layers 60, 61 separated by an electricaUy insulating or non-conductive material 62, aH of which are opticaHy transparent or at least substantiaHy optically trans ⁇ parent; and between the liquid crystal color layers 3', 4', are electrode layers 63, 64 and an opticaHy transparent insulator 65.
  • the electrode layers 60, 63 have horizontal electrode strips, as is shown in end view in Fig. 9, similar to the electrode strip arrangement Hlustrated in Fig. 8; and the electrode layers 61, 64 have vertical electrode strips shown in end view in Fig. 9 arranged in a way simHar to the electrode strips Ulustrated in Fig. 7. It wiH be appreciated that other electrode patterns, arrangements and configurations may be employed consistent with the invention to effect appHcation selectively of electric field to certain portions of respective Hquid crystal color layers in the display 1'.
  • respective electrodes in layers 44', 60 may be selectively energized or not to effect application or not of an electric field at respective portions of the Hquid crystal color layer 2'.
  • respective electrode strips in the electrode layers 61, 63 may be selectively energized or not to apply or not electric field to respective portions of the Hquid crystal color layer 3', and the same is true with respect to the electrodes in the electrode layers 47', 64 with respect to the Hquid crystal color layer 4'.
  • each liquid crystal color layer 2', 3', 4' has a dedicated respective pair of electrode layers for affecting the encapsulated Hquid crystal material in the color layer.
  • Examples 1-3 describe the making of three differently dyed encapsulated Hquid crystal materials. Each such material may be used, for example, in a respective liquid crystal color layer of a Hquid crystal color display as is Ulustrated and described herein.
  • EXAMPLE 1 This is an example of making pleochroic dyed encapsulated liquid crystal, which absorbs blue light and transmits green and red Hght.
  • the polymer was weighed out in a beaker.
  • the liquid crystal was weighed out, was placed on a hot plate, and was heated .lowly.
  • the dye was weighed out on a balance and was added very slowly to the liquid crystal, being stirred until aU the dye went into solution.
  • the liquid crystal and dye solution then was fUtered through a standard MilHpore filtering system using 8 ml. filter paper.
  • the fUtered Hquid crystal and dye solution was stirred into the polymer using a Teflon rod.
  • the mixture was encapsulated by placing the same in a ⁇ oUoid miU that was operated at medium shear for five minutes.
  • the emulsion produced was puUed as a film on a conductive polyester sheet.
  • Example 1 Carry out the steps of Example 1 using the materials of Example 1 except substitute 0.5 gram of indophenol blue, (a cyan dye— red absorber and green and blue transmitter), the latter ingredient being a pleochroic dye, for the yeUow dye of Example 1. Operation was the same as in Example 1 except for the color of filtered light.
  • EXAMPLE 3 This is an example of making pleochroic dyed encapsulated Hquid crystal, which absorbs green light and transmits blue and red Hght.
  • the polymer was weighed out in a beaker.
  • the Hquid crystal was weighed out, was placed on a hot plate, and was heated slowly.
  • the dye was weighed out on a balance and was added very slowly to the Hquid crystal, being stirred until aU the dye went into solution.
  • the Hquid crystal and dye solution then was filtered through a standard MilHpore filtering system using 8 ml. filter paper.
  • the filtered Hquid crystal and dye solution was stirred into the polymer using a Teflon rod.
  • the mixture was encapsulated by placing the same in a coUoid miU that was operated at medium shear for five minutes.
  • a sUde was taken using a Teflon rod, and upon inspection showed medium size capsules of about 3 to 4 microns in diameter.
  • the material was filtered through a MilHpore screen filter, and another sUde was taken; on inspection there was very Httle change in capsule size from the first-mentioned inspection.
  • the emulsion produced was puUed as a fUm on a conductive polyester sheet using a doctor blade set at a 5 mU gap.
  • a multicolor device can be made using any two or more of the dyed encapsulated liquid crystal materials mentioned above in Examples 1-3 according to the invention to achieve different respective color combina ⁇ tions, as may be desired. Also, any two Hquid crystal materials, each having a different turn on voltage or frequency may be used according to the invention, each being prefereably dyed with a different respective pleo ⁇ chroic dye.
  • the multicolor device may be either voltage responsive, frequency responsive, or both, and may, if desired, use separate pairs of electrodes or shared electrodes, or both.
  • EXAMPLE 4 This is an example of operation of a multicolor liquid crystal display, according to the invention, having two Hquid crystal color layers for example respectively formed according to Examples 1-3.
  • Red dye either Sudan-EH or Sudan-IV
  • indophenol blue was in the other layer of encapsulated Hquid crystal.
  • the dyes as preferably is the case in the several examples included in this disclosure, were pleochroic. In operation, when both layers were off, the device or area thereof which was off, was black; with the red off and blue on, the device or area was red; with the blue on and red off, the device or area was blue; and with both layers on, the device or area was generaHy clear or transparent.
  • Fig. 10 is Ulustrated a front view of a liquid crystal color display 70 which may be of the type designated 1 in Fig. 1 or designated 1' in Fig. 9.
  • the size selected for the display 70 i.e. the cross-sectional area of the viewing side or surface thereof, may be substantially unlimited. Exem ⁇ plary sizes may be from s aUer than one square inch of area for the viewable or observable surface 71, i.e. the surface ordinarUy viewed by an observer, to several square inches, to television size (from smaU screen size to large screen size), to bUlboard size, etc.
  • Hquid crystal color display 70 would be smaU and large size displays, television, motion picture-type displays, bUlboard displays, and so on.
  • pixel-Hke areas such as those designated 72, 73, 74, which represent respective portions of Hquid crystal color layers in the display 70 where respective crossed electrodes, such as electrodes 441, 45i (Fig. 10) or electrodes 44a, 45a (Figs. 7 and 8) cross each other on opposite sides of at least one liquid crystal color layer; see, for example, the description above concerning the portion of Hquid crystal color layer 2 located between portions 51, 52 or electrode strips 44a, 45a (Figs. 6-8).
  • each pixel-like area viewable at the observable surface 71 of the Hquid crystal color display 70 are the respective opticaUy aHgned portions of several respective liquid crystal color layers, such as the layers 2, 3, 4 of Fig. 6 or 2', 3 r , 4 r of Fig. 9.
  • electrical circuitry 75 Associated with the liquid crystal color display 70 in Fig. 10 is electrical circuitry 75, the purpose of which is to energize (or not) respective electrodes of the display 70 selectively to apply (or not) an electric field to a particular portion, e.g. that behind one of the pixel-Hke areas 72, 73, 74, of respective Hquid crystal color layers thereby to create a desired image, whether fixed or moving, appearing at the observable surface 71.
  • two exemplary electrode strips 44i, 45i are Ulustrated. It wUl be appreciated that the circuit 75 may be coupled to aU of the electrodes, such as the multiple electrodes shown in Figs.
  • the pixel-like areas may be relatively large or smaU, depending upon the desired resolution required for the liquid crystal color display 70, and depending on whether or not merging of colors is desired in an additive fashion at the observable surface 71.
  • the exemplary circuit 75 includes an input circuit 76 for receiving an input signal, such as a video signal, for example having luminence and chromaticity information; in this example the display 70 may be employed as a color television screen, monitor, etc.
  • the circuitry 75 similarly could be employed with the display 70 for producing a color optical output of a physical size larger than conventional television screen or even large screen television size.
  • the input circuit 76 is coupled to a decode or demodulate circuit 77, which separates the chromaticity and luminence information and delivers appropriately responsive output signals to driver circuit 78.
  • the driver circuit 78 may amplify and/or synchronize the information received from the circuit 77 and then couples the same to drive a scanning circuit 79.
  • the scanning circuit 79 that preferably repetitively addresses or scans the individual pixel-Hke portions of respec ⁇ tive liquid crystal color layers located behind the pixel-like areas 72, 73, 74, etc. selectively to apply (or not) an electric field across a given pixel-Hke portion of a particular liquid crystal color layer, e.g. the portion of the Hquid crystal color layer 2 (Fig. 6) bounded or aligned with the portions 51, 52 of the electrode strips shown in Figs. 7 and 8, and to control the magnitude of any applied electric field.
  • Such scanning or addressing may be similar to the type of scanning or addressing encountered in conventional color television picture systems.
  • the individual cir ⁇ cuits 76-79 may be of the type and/or may operate according to the type disclosed, for example, in U.S. Patents Nos. 3,627,924; 3,636,244; and 3,639,685; the disclosures of which hereby are incorporated in their en ⁇ tireties by reference.
  • the latter two patents directly relate to color television signal decoding and utiHzation in a color television system
  • the first-mentioned patent discloses a system for scanning electro- luminescent points in an overaU electroluminescent array. Such scanning may be employed in accordance with the present invention, and such signal usage and coding may be employed, too, according to the present invention to achieve the desired multicolored display output from the Hquid crystal color display 70.
  • the Hquid crystal color display 70 as driven by the circuitry 75 may operate in a truly subtractive mode in which it is intended that only the color produced by a given pixel 72, 73, 74, etc. will have an optical influence on the observer - the pixel size would be relatively large in this case e.g. so as not to produce substantial color addition when viewed relatively close up.
  • the subtractive color definition is, of course, a function of the optical fUtering effected as input Hght 9 (Fig. 1) is transmitted through the various layers of the display 70 and ultimately is emitted as output Hght 10. Alternatively, the size of the individual pixels 72, 73, 74, etc.
  • the display 70 may be relatively smaU so that additive color operation, such as that disclosed in eopending U.S. Patent AppHcation Serial No. 480,461 mentioned above is effected.
  • This latter may be considered a subtractive/additive optical mode.
  • the pixels are rather smaU, e.g. Hke color dots of a color television, the colors produced at respective proximate pixels are added or, in a sense, integrated, by the eye of an observer.
  • the colors of individual pixels are produced by subtractive optical technique of the multiple dyes in respective volumes of Hquid crystal making up the respective pixel.
  • the display 70 may be Uluminated by ambient illumination from the non-viewing side or by an additional Hght source provided at the non-viewing side.
  • the Hquid crystal color displays 1, 1' and 70 may be employed for a variety of purposes including, for example, to effect color display of data, characters, informa ⁇ tion, picures, etc. or simply to control light, on both smaU and large scale.
  • Exemplary pleochroic dyes and combinations thereof to effect particular color outputs are mentioned above, for example in connection with Table HI, but it wUl be appreciated that other dyes and color fUtering combinations, including fewer or more than three dyes described in detail above in the preferred embodiment, may be employed according to the invention.
  • the invention may be used to display over a long period of time a single image or picture or may be employed to produce a moving picture type of output. The output itself may be viewed directly, photographed, projected, etc.
  • an additive may be used in the Hquid crystal to expedite return to distorted alignment.
  • an encapsulated Hquid crystal 80 is shown including a capsule waU 81 having operationally nematic liquid crystal material 82 in the interior volume 83 thereof.
  • An exemplary additive namely a cholesteric chiral additive 84, is in solution with the liquid crystal material 82, although the additive is shown for faciHty of illustration at a central location in the capsule volume 83 because the function thereof primarily is with respect to the liquid crystal material remote from the capsule waU.
  • the encapsulated liquid crystal 80 is shown in field-off, distorted, curvilinearly aligned condition, mode or phase with the liquid crystal material distorted in the manner described above.
  • the liquid crystal material most proximate the waU of the capsule tends to be distorted to a shape curved Hke the inner boundary of that waU (or generaUy normal thereto).
  • the chiral additive 84 tends to expedite return of the operationaUy nematic Hquid crystal material more proximate the central portion of the capsule to the curviUnearly aligned phase upon the removal of an electric field.
  • the encapsulated liquid crystal material employed in the several embodiments of the invention may include fluidicaUy interconnected volumes or capsules Ulustrated at 90 in Fig. 12.
  • the curvilinearly aHgned phase of the Hquid crystal material contained in such volumes may be oriented generaUy paraUel to the capsule walls or normal with respect thereto (radial with respect to the center of the capsule).
  • Fig. 12 only two interconnected volumes are shown, but it wiU be appreciated that individual volumes may be connected to one or more other such volume(s).
  • the encapsulated Hquid crystal material 80 (Fig. U) and/or 90 (Fig. 12) may be employed in the various embodiments of the invention described in detaU dbove.
  • an advantage of sharing electrodes e.g. in the display 1 of Fig. 1, is the minimizing of optical absorption by the electrodes.
  • the use of a single pair of electrodes to apply electric field to two differently dyed Hquid crystal color layers, e.g. layers 2, 3 of Fig. 1 would further reduce the electrode requirements for a multicolor display.
  • a discrimination function is needed to determine which layer(s) is (are) to turn on in response to a particular prescribed input, e.g. electric field.
  • a multUayer, multicolor shared (two) electrode Hquid crystal display 100 is Ulustrated.
  • the display 100 is generaUy simUar to the display 1 (Fig. 1) and may include various one or more of the several features of the invention described herein.
  • the display 100 includes a pair of liquid crystal layers 2, 3 that contain different pleochroic dye, e.g. magenta in layer 2 and cyan in layer 3; that are not separated by an electrode; and that share a single pair of electrodes (or electrode strips) 44, 46'.
  • Electrode 46' is analogous to electrode 46 in Fig.
  • each of the electrodes 44, 46' may be plural strips of electrodes, as is described above, to produce a static or dynamic multicolor output by selective energization of respective electrode strips.
  • the layers 2, 3 may be formed as in the above Examples and may be puUed separately on the support medium 7.
  • the layer 2 may be puUed first directly on the electrode layer 44 and support 7. After the layer 2 has adequately cured, the layer 3 may be puUed on top of layer 2, and then the electrode layer 46' may be appHed.
  • Other techniques also may be used to form the display 100.
  • the layers 2, 3 are in intimate but non-mixing relation. Such layrs function in optical serial relation. However, due to the intimate engagement and the coextensive extent of the layers 2, 3 (and possibly also due to thinness thereof), paraUax is avoided. Rather, on being viewed, the two layers 2, 3 appear as one layer. Moreover, using a thin dividing electrode, e.g. as the electrode 45 in Fig. 1, paraUax also is eliminated or substantiaHy eliminated in the optical serial device of the invention.
  • the layers 2, 3 preferably have at least one different electrical characteristic, e.g. frequency response, voltage threshold requirement to align with respect to an applied field, etc., to discriminate the prescribed input thereto, as is described in further detail below.
  • the Hquid crystal, and thus the pleochroic dye, in layer 2 may respond, e.g. aHgn, with respect to an electric field appHed at one threshold voltage level, say 10 volts; and the layer 3 may be simUarly responsive only when the voltage exceeds a second threshold of, say, 20 volts. Therefore, in response to an electric field applied by electrodes 44, 46' below the lower threshold or in the absence of such field, incident light 9 (e.g.
  • the display 100 is capable of producing multicolor output using only the two terminals, i.e. connections of the electrodes 44, 46' or respective strips thereof to a single power source, thus simpHfying the display.
  • An important advantage of the display 100 eliminating the need for an electrode between the layers 2, 3 is the eliminating of the optical absorption of such electrode; therefore, a corresponding brightening of the output from the display is achieved.
  • Discriminating the electric field input to both layers 2, 3 as a function of the difference in voltage response of the Hquid crystal layers 2, 3 in the display 100 can be achieved by using different liquid crystal materials that have different respective dielectric anisotropy characteris- tics in the respective layers 2, 3.
  • the 10% material (item 1 in Table I above) has one dielectric anisotropy characteristic making the same responsive to a relatively high voltage
  • the 40% material (item 3 in Table I) has a different dielectric anisotropy characteristic, making the same responsive to a lower voltage. Therefore, the layer 2 may be comprised of the 40% material containing, say, magenta dye, and the layer 3 may be co prised of the 10% material containing, say, cyan dye.
  • the Hght output 10 or 10a would be blue if the incident light 9 were white (see Table HI above); above the first but below the second threshold, the Hght output would be cyan; and above the second the output would be white— this assuming absence or transparency of layer 4 in the display 100.
  • Another example of such use of display 100 would be to include Sudan-HI or Sudan-IV dye, each of which is red, in the 10% cyano Hquid crystal material (item 1 in Table I) and indophenol blue dye, which is a cyan dye, in the 40% cyano-l ⁇ quid crystal material (item 3 in Table I). Since the red and cyan dyes are complementary, the Hght output is black when the liquid crystal in the layers 2 and 3 is in field-off curviUnearly aHgned condition or mode. Above the first threshold voltage, the 40% material turns on and the light output from the display becomes red due to fUtering by the Sudan-HI or Sudan-IV dye. Above the second threshold no fUtering occurs and the light output from the display is white,* i.e. the display is clear.
  • the layers 2, 3 in display 100 are electricaUy matched so that the voltage appHed thereto between the electrodes 44, 46' is divided substantiaHy equaUy for simpHcity of various operational considerations.
  • the dielectric constants and dielectric anisotropy of the different Hquid crystal materials in the differ ⁇ ent layers 2, 3 are different, it may be necessary to make one layer thicker than the other to achieve the desired electrical characteristics, e.g. generaUy equal voltage drop across the layers.
  • a modified display 100' Hke the display 100 has an additional liquid crystal color layer 4.
  • the layer 4 can perform selected further fUtering of light by the contained/encapsulated Hquid crystal therein; preferably the layer 4 includes a pleochroic dye different in color from the dye in the layers 2, 3.
  • Electrodes 47' (Hke the electrode(s) 47 but preferably crossed relative to electrode strips in electrode 46') co ⁇ operate with electrodes 46' to apply electric field to the liquid crystal in layer 4, as above. Color output would foUow Table m above, for example.
  • the display 100' may be made in the same way as the display 100, but with the layer 4 added above the electrode layer 46' foUo ed by the application of the electrode layer 47'. Other techniques also may be used to make the display 100'.
  • the various displays herein may include more than two or three color layers of liquid crystal material.
  • capsule-Hke environments for the dyed liquid crystal material can be formed in such a way as to maintain substantial isolation of the liquid crystal in one capsule from the liquid crystal in another capsule or otherwise in contact with the exterior of the first-mentioned capsule.
  • isolating capsules defining volumes of contained liquid crystal may be used in the several embodiments of the invention.
  • such capsules can be formed, for example, by a condensation reaction, more preferably by a polycondensation reaction, and most preferably by a reaction that yields a cross-Unking or cross-Unking type result.
  • such capsules are formed from a solution of the liquid crystal material and a cross-linkable polymeric material, on the one hand, and another cross-linkable polymeric material on the other hand; the two polymeric materials are reactable to effect a cross- linking of the polymer, especiaUy at the surface, to form a capsule which is water-insoluble and water-impermeable.
  • a solvent such as chloroform can be utUized.
  • Such resulting cross-Hnked polymer contain ⁇ ment medium has substantial isolating characteristics so as to maintain the dyed liquid crystal therein substantiaUy isolated from that in other capsules. Ad vantages of such isolation are apparent from the further description below. However, it wUl be realized that such isolation improves longevity of a Hquid crystal display employing such materials; such material also avoids deterioration due to external environments, water, humidity, dirt, chemicals, etc.
  • such cross-Hnking is achieved by mixing a aleic anhydride derived eopolymer, for example one known as poly(methyl vinyl ether/maleic anhydride) made and/or sold by GAF Corporation under the identification Gantrez 169, with the dyed Hquid crystal material.
  • the dyed material may be one of the type described in the several recipes in Table I above or the 8250 material also described above.
  • a solvent, such as chloroform, also may be added to facilitate the dissolving of the maleic anhydride polymer in the Hquid crystal material itself.
  • the solution just mentioned is mixed with polyvinyl alcohol, and a cross-Hnking reaction occurs to form a water insoluble polymer.
  • Fig. 15 shows the formation of a capsule using Hquid crystal and Gantrez 169 in the center 150; and PVA ajid water 151 about the outside.
  • the cross-linking reaction occurs at the boundary of the Hquid crystal and Gantrez mixture 150 to form a capsule.
  • the result is the formation of an insoluble fUm or wall confining the Hquid crystal material and dye within the capsule.
  • the fUm is insoluble in both the Hquid crystal and in the water.
  • the invention uses techniquies in forming such capsules that do not reduce resistivity of the Hquid crystal or containment medium.
  • One such technique is the Soxlet extraction purification method mentioned above.
  • fundamentaUy the isolating capsules are formed by a pair of reactants, one of which is water soluble and the other of which is soluble in the liquid crystal material, and those reactants together undergo a poly- condensation reaction.
  • EXAMPLE 5 This example demonstrates the use of cross-Hnking with dyed Hquid crystal material.
  • liquid crystal Gantrez (or other cross- linkable polymer) and chloroform be intersoluble.
  • ester Hquid crystal materials may be used, such as those identified in Table I and the 8250 material mentioned above. Also other materials may be used as long as the cross-Hnking is achieved to provide strength, durabUity and insolu- biHty of the capsules.
  • the foregoing chemical cross-Hnking technique can be used with some of the dyes, such as D-54 and indophenol blue, which are compatible with the several materials used.
  • An object of the cross-Hnking technique is to isolate the liquid crystal in a isolating capsule environment resulting in a product that has a long shelf Hfe and operational Hfe.
  • the foregoing technique can be used to produce two or more different groups of capsules, respectively containing different Hquid crystal materials, one Hquid crystal material containing one dye and the same or another Hquid crystal material containing a different dye, etc.
  • the groups of capsules can be mixed together without destroying the integrity of the individual capsules; thus, the individual Hquid crystal materials and dyes, if used, remain isolated from each other although individual capsules of respective Hquid crystal material themselves are mixed.
  • Examples 1-4 may be practiced using the cross-linking or polycondensation reaction technique of Example 5 as long as the desired cross-Hnking or polycondensation reaction occurs.
  • Exemplary cross-Hnking producing materials or condensation agents may be an aldehyde, a dialdehyde, a polycarboxyHc acid or a polycarboxyHc anhydride; and more specificaUy may be at least one of the group gluteral aldehyde, dioxal glycoxal acetaldehyde, formaldehyde, phthaHc anhydride, maleic anhydride, poly(methyl vinyl ether/maleic anhydride), and polyvinyl- methoxymaleic anhydride.
  • Further condensation agents would be diiso- cyanates, such as toluene diisocyanate, hexolmetholene diisocyanate, and others that will undergo polycondensation reaction with alcohols, for example.
  • the water soluble polymer part of the ingredients to form the isolating capsules may be, for example, the mentioned polyvinyl alcohol, or any polyhedric alcohol. Examples would be ethylene glycol and water, propylene glycol and water, or glycerine and water.
  • Hquid crystal material dye, containment medium, cross- linkable polymer, e.g. maleic anhydride containing copolymer, etc. to achieve the desired cross-Hnked, isolating, relatively insoluble capsules or in any event volumes containing the liquid crystal material, whether or not dyed.
  • polyvinyl alcohol can be replaced by other polymers which can cross Hnk the cross-Hnkable polymer in the solution.
  • Fig. 16 an example of a multicolor display device 200 employing such a mixture 201 of a group or pluraUty of red-dyed Hquid crystal capsules 202 and a group or pluraHty of green-dyed Hquid crystal capsules 203 is shown.
  • the capsules 202, 203 are the isolating capsules of cross-linked materials described above, and, therefore, such capsules pro ⁇ vide adequate isolation of one dyed Hquid crystal material from the other. Since the capsules 202, 203 are mixed and only one pair of electrodes 44, 46' (or electrode strips) is used, a means to discriminate the electric field input, e.g. according to magnitude, ordinarUy would be provided.
  • the Hquid crystal material in one or both of the groups of capsules 202, 203 can be aligned or not and a multicolor output can be achieved.
  • the actual color of the output Hght would depend on which, if any, of the liquid crystal capsules 202, 203 is in field-on paraUel aHgned (with the electric field) condition and which, if any, is in curvilinear aligned condition.
  • the described cross-linking would not occur and the so-caUed isolating, water insoluble capsules of cross-linked polyester material would not be obtain ⁇ able.
  • it may be necessary to maintain suitable isolation between respective dyed Hquid crystal materials e.g. by maintaining separate layers of the same.
  • one layer of volumes of dyed liquid crystal material in an emulsion of PVA or other containment medium could be pulled on a support; after such emulsion has cured or otherwise stabilized, a second layer of a differently dyed Hquid crystal material in a containment medium could be puUed on top of the first-mentioned one; and so on.
  • one or more electrode layers, transparent film layers, etc. could be located between the dyed Hquid crystal layers.
  • Such a display 210 is Ulustrated in Fig. 17 using one layer 211 of actual cross-linked or isolating capsules 212 of dyed Hquid crystal and a separate layer 213 of PVA 214/dyed liquid crystal 215 which form an emulsion 216.
  • each layer may include more than one layers of capsules or volumes of dyed Hquid crystal material, as is seen in Fig. 17.
  • the walls of the capsules 212 effect the needed isolation to prevent the two different respective Hquid crystal and dye mixtures from mixing with each other. It also may be possible to mix the capsules 212 in with the emulsion 216 to form a generaUy homogeneous layer of capsules containing one Hquid crystal material and dye therein and further volumes of the other Hquid crystal material and dye essentiaUy contained in the overaUy containment medium, e.g. PVA.
  • Hquid crystal materials For discriminating between different magnitude or voltage levels of electric field simultaneously appHed to differently dyed Hquid crystal materials in separate volumes, e.g. in the displays 100, 100', 200, 210 described above, the use of two Hquid crystal materials that have different respective field-on alignment threshold voltage levels may be used.
  • voltage threshold discrimination capabUity is mentioned above in relation to Figs. 13 and 14, namely, the proposed use of the 10% and 40% cyano Hquid crystal materials identified in Table I above.
  • Each of such liquid crystal materials has a different voltage threshold which is required before the Hquid crystal wiU turn on to paraUel aHgnment with respect to the appHed field overcoming the force of the capsule or volume containing the liquid crystal material and tending to force the same to the curviUnearly aHgned or distorted structure.
  • threshold voltage may be a function of capsule or volume size, as was mentioned above and is described further below.
  • the use of at least one cross-over Hquid crystal material is another way to effect discrimination as a function of frequency and voltage of electric field applied by a single pair of electrodes.
  • a cross-over Hquid crystal material is one that has a character ⁇ istic that changes as a function of input.
  • the Hquid crystal material may have two different dielectric anisotropies - one dielectric anisotropy, e.g. negative, at one frequency (say at a low frequency) of applied electric field and a second different dielectric anisotropy, e.g. positive, at a different frequency (say at a high frequency). Therefore, at different frequencies of electric field one can obtain different respective operation of the liquid crystal, such as selective switching from the same Uquid crystal material.
  • An exemplary cross-over liquid crystal materials that are operationaUy nematic are, as foUows:
  • KOD-M by Kodak (a mixture of 50% p-octylphenyl 2-chloro-4-(p-pentyl benzoate + 50% p-pentyl (phenyl 2-chloro-4-(ppentyl benzoyloxy) benzoate); 3333, by Roche; 3421, by Roche.
  • a liquid crystal device 200' similar to the display 200 described above, is able to discriminate the frequency and voltage or ampHtude of an input electrical signal.
  • Such Hquid crystal device 200' includes plural volumes 204 of frequency responsive Hquid crystal material 205.
  • the Hquid crystal material is contained in a containment medium 206 as is described herein.
  • An example of such Hquid crystal material is the cross over 2461 liquid crystal material mentioned above. Examples of containment media also are described herein.
  • the liquid crystal material includes pleochroic dye 28 mixed therewith to operate in a guest-host relation, as is described herein.
  • Such liquid crystal device 200' is capable of discriminating between input electrical signals according to voltage and frequency.
  • the Hquid crystal generaUy is in the distorted alignment configuration shown in Figs. 3 or 4, described above, which causes Hght scattering or causes corresponding pleochroic dye 28 structure to absorb a given color light.
  • the electrodes 46', 44 In response to appHcation of an electric field by the electrodes 46', 44, such that the field frequency is relatively low and the voltage amplitude is above the threshold level of the liquid crystal material to cause the Hquid crystal structure to aHgn generaUy in paraUel with such field, such generaUy paraUel aHgnment wiU occur, e.g.
  • the Hquid crystal structure wiU change from alignment in paraUel with the electric field to non-aHgnment or to alignment in a generaUy perpendicular direction with respect to the electric field, which may also be referred to hereinafter as non-aHgnment, as the operative optical effect wiU be the same.
  • Hght scattering wiU occur if the extraordinary index of refraction of the Hquid crystal material is different from the index of refraction of the medium in which it is contained; and/or if pleochroic dye is contained in the Hquid crystal, increased absorption wiU occur.
  • ZL1-2461 nematic type Hquid crystal material Several properties of ZL1-2461 nematic type Hquid crystal material include the foUowing: Dielectric anisotropy, delta E (E is dielectric coefficient because E may change as a function of direction with respect to the alignment of the Hquid crystal, i.e. structure orientation of the Hquid crystal, frequency, etc.), at low frequency, e.g. below about 3 KHz at room ambient temperature, is +3.
  • E ara u e ⁇ is 7.8, and Eperpendicular i- 3 4.8 (paraUel and perpendicular refer to ordinary and extraordinary directional considerations relative to alignment of the axis of the Hquid crystal structure). Switch over frequency is 3 KHz at room ambient temperature.
  • Switch over frequency is that frequency of the applied electric field at which the dielectric anisotropy of the cross-over liquid crystal material changes from positive to negative and vice-versa.
  • Dielectric anisotropy at the relatively higher frequency of 10 KHz is -1.5.
  • the 2461 Hquid crystal is compatible with several other liquid crystal materials. Such compatibility is manifest in the foUowing operative example.
  • the 2461 Uquid crystal material matches weU with the 10% cyano liquid crystal material mentioned above. Both the 2461 and the 10% cyano materials turn on (turn on means the Hquid crystal structure aHgns with respect to the appHed field and preferably reduces scattering and/or absorption and increases optical transmission) at the same time and in response to the same magnitude electric field at low frequency. However, at high frequency (say, 10 KHz.), only the 10% cyano liquid crystal material would turn on at such magnitude of electric field; since the 2461 material would have a negative dielectric anisotropy at high frequency it would not turn on.
  • the cross-over material may be used in the several embodiments of the invention disclosed herein.
  • the 2461 Hquid crystal has negative dielectric anisotropy, wiU not align with respect to the field, and accordingly wiU cause the dye therein to fUter Hght; while the 10% cyano material remains in paraUel alignment to the field so the dye therein wUl not effect or wiU only minimally effect fUtering. d.
  • a further possibUity is that the field is appHed at low frequency and adequate threshold voltage to turn on the 2461 material but the voltage is inadequate to turn on the 10% cyano material— in this case only the dye in the 10% cyano Hquid crystal containing volumes would effect fUtering, and the 2461 Hquid crystal and dye would have no or minimal fUtering effect.
  • Combinatlon/compatibiHty of cross-over liquid crystal with other liquid crystal materials It is not critical which of the above recipes (Table I, for example) of Uquid crystal materials is used with the cross-over material. For assuring turn on at the same time at low frequency, one must use liquid crystal material that has a dielectric anisotropy which is about the same as the low frequency dielectric anisotropy as that of the 2461 Uquid crystal material. For example, 10% cyano and 2461 Uquid crystal materials may be used. Another example would be 2461 material and 2U6-U0 Hquid crystal material, also by Merck.
  • the delta N's optical anisotropy- -N is index of refraction
  • delta E's match for these except that the 2461 turns off at high frequency or does not switch at high frequency because at high frequency the 2461 Uquid crystal material has negative dielectric anisotropy.
  • Hquid crystal materials that have different cross-over frequencies. Therefore, it would be possible to obtain discrimination at more than one frequency. Using one of such Hquid crystal materials in one group of volumes and another in another group, the Hquid crystal materials preferably would not mix. Examples of such Hquid crystal materials useful according to this arrangement are 3421 by Roche that has a low cross-over frequency of about 400 Hz. and 3333 Uquid crystal by Roche that has a relatively higher cross over frequency of 3.2 KHz. CAPSULE SIZE CONSIDERATIONS Capsule size can play an important role in accompHshing voltage discrimination function for the several layers of encapsulated Hquid crystal material.
  • the smaUer the capsule for a given liquid crystal material, the larger the voltage required to switch the liquid crystal material to aHgned state. Accordingly, the same liquid crystal material can be used in each of the Uquid crystal layers, but each layer is formed of capsules of different respective size. In this way voltage discrimination can be accompHshed with the same Uquid crystal.
  • a multicolor display device 220 is Ulustrated.
  • Such device 220 has two layers 221, 222 of volumes or capsules 223, 224 of Hquid crystal.
  • the Hquid crystal in layer 221 is dyed one color, and that in the other layer 222 is dyed a different color.
  • the total thickness of each layer though, preferably is the same, since the impedance and dielectric values of the layers would be the same; this helps assure balanced operation and balanced electrical and optical effects.
  • each layer is the same thickness, has similar properties, has the same concentration dye and, thus, the same effective filtering capablity.
  • the liquid crystal in the layer 221 having the larger volume capsules 223 switches at a relatively lower voltage and the liquid crystal in the layer 222 of smaUer volumes 224 requires a relatively greater voltage to switch on to the aligned generaUy transparent mode.
  • volume/capsule size considerations as weU as the various other features of the invention may be used together to achieve the particular operational characteristics of multicolor subtractive color or serial fUtering accompHshed in the multicolor optical devices of the invention as are described in detail above.
  • both voltage and frequency are used to discrimi ⁇ nate the input to a pair of different Uquid crystal materials.
  • one of the dyes actuaUy cannot be encapsulated with the Gantrez according to the method described above with the cross-Hnking to obtain isolating capsules, because the dye contains alcohol and would react with the Gantrez.
  • layer 211 has indophenol blue dye and is formed of the 5% organo Hquid crystal material identified above.
  • Layer 213 has Sudan-HI (red) pleochroic dye therein and is formed of 2461 Hquid crystal which is frequency dependent, vis-a-vis dielectric anisotropy.
  • Layer 2U is comprised of isolating cross-Hnked capsules, and layer 213 is comprised of a stable emulsion of volumes of dyed Hquid crystal in a polyvinyl alcohol containment medium. The threshold level of the 5% cyano Hquid crystal material to turn on/align with respect to the field exceeds that of the 2461 Hquid crystal (at low frequency).
  • both layers 2U and 213 are field-off and for incident white light input the output is dark or black.
  • the 2461 layer turns on (liquid crystal aHgns) and dye therein becomes effec ⁇ tively transparent, while the blue dye in the 5% material layer continues filtering to produce a blue output.
  • the 5% material turns on and the 2461 material stays on, whereupon the display is clear.
  • the 2461 material turns off and the 5% material stays on, whereupon the display produces a red output.
  • a first layer of one color dyed encapsulated liquid crystal material could be cast on a support, foUowed by a second layer of a different color dyed encapsulated Hquid crystal material, and, if desired, even a third, etc.
  • Each Hquid crystal material may be responsive to a different voltage or frequency than the other(s) to achieve discrimination of input field to produce a multicolor output.
  • BALANCING ELECTRICAL CHARACTERISTICS While, on the one hand, it is desirable to achieve the above- mentioned electric field discriminating function, on the other hand it is desirable to balance the electrical characteristics of the Hquid crystal layers. In particular, it would be desirable to balance electrical impedance of the layers so that for a given input field the voltage drop across each layer would be at least about the same. Such balance facilitates operational consideration as each layer or capsule discriminates the appHed electric field. Although it is possible for a multicolor display, e.g. of the type disclosed in Fig. 17, for example, to function with electricaUy unbalanced characteristics, the achieving of desired balance simpHfies construction and operation of the display. Such balancing also may facilitate the discrimina ⁇ tion function and may prevent possible damage to the Hquid crystal material and/or containment medium due to over-driving by excessive voltage to switch one or both layers of an electricaUy unbalanced display.
  • Such balancing of dye concentration may be according to an equation for intensity I of light transmitted through a Hquid crystal layer containing pleochroic dye as a function of the incident Hght intensity I 0> thickness T of the layer, and concentration B of the dye in that layer, as foUows:
  • a multicolor device 230 embodying this example is Ulustrated in Fig. 19.
  • Materials a. 40% cyano liquid crystal mixture mixed with indo ⁇ phenol blue pleochroic dye. The concentration of dye in this first layer 231 wUl be one-fourth the concentration of dye used in the second layer because the thickness of this first Hquid crystal layer wiU be four times the thickness of the second Hquid crystal layer in order to achieve the desired balance of electrical characteristics between the two layers to accompHsh the operation below. b. 10% cyano Hquid crystal mixture mixed with Sudan- UI (red) pleochroic dye in this two dye multicolor system.
  • the concentration of dye in the instant layer 232 wiU be four times the concentration of dye in the first-mentioned layer 231; but the thickness of this instant layer 232 wUl be only one fourth the thicnkess of the first-mentioned layer.
  • Example 7 This example is the same as Example 7 except that a yeUow (negative blue) dye and a true blue dye were used.
  • the results for increasing voltage are, as foUows: a. Both off: Black.
  • plural pleochroic dyes may be mixed to derive a dye that is a different color or has different properties relative to the constituents.
  • Sudan-I and indophenol blue pleochroic dyes may be mixed for the purpose of forming a green dye, which is used as the dye for one of the encapsulated liquid crystal materials, e.g. in the multicolor display device 200 of Fig. 16 or in the foUowing Example 9.
  • green pleochroic dye having suitable color and longevity /non-fade characteristics, and that is why the mixture is useful.
  • This example is the same as Examples 7 and 8, except that a mixture of Sudan-I and indophenol blue pleochroic dyes were used as a green dye and D-37 magenta pleochroic dye was used as the other dye.
  • the multicolor device worked, as foUows: a. Both off: Black. b. One or the other on: Green or magenta. c. Both on: Clear.
  • the dye can be mixed in either direction. Concentration of the dye plays a big part in balancing out the absorption characteristics of the materials used and of the resulting color output. These can be determined pragmaticaUy, if desired. Importantly, though, the electrical characteristics of the layers are balanced to facUitate appHcation of electric field and determination of the discrimination and/or other operational functions of the multicolor display device according to the invention.
  • a convenient multiplexed driving technique may be employed selectively to provide (or not) appropri ⁇ ate prescribed electrical input to the liquid crystal material(s) to effect alignment or not of the structure thereof with respect to appHed electric field.
  • a Hquid crystal device 300 shown in Figs. 21 and 22 uses such multiplexed driving technique.
  • the Hquid crystal device 300 has plural, two are shown, layers 302, 304 of volumes 306, 308 of Hquid crystal material 310, 312.
  • the Hquid crystal 310 in the first layer 302 is cross over liquid crystal material that has a first cross over frequency.
  • the Uquid crystal material 312 in the second layer 304 may be non-cross over Hquid crystal material or may be cross over Uquid crystal material having the same or a different cross over frequency than the first Hquid crystal material 310.
  • One example of cross over Uquid crystal material is the 2461 material mentioned above.
  • Bucher et al in "Frequency-Addressed Liquid Crystal Field Effect", AppHed Physics Letters, Vol. 25, No. 4, 15 August 1974, pages 186-188. The entire disclosure of Bucher et al is incorporated by reference.
  • the Uquid crystal material 310 is of the cross over type and the liquid crystal material 312 is of the non-cross over type.
  • the cross over Hquid crystal material 310 has positive dielectric anisotropy when the electric field appHed thereacross is at relatively low frequency and has negative dielectric anisotropy at relatively higher frequency; the Hquid crystal material 312 has positive dielectric anisotropy.
  • the voltages required to initiate a tendency of the liquid crystal material to align and to achieve fuH aHgnment with respect to appHed electric field vis-a-vis the Hquid crystal materials 310, 312 are different. Other parameters, such as alignment responsiveness voltages also may be selected for various other embodiments within the spirit and scope of the invention.
  • the Hquid crystal device 300 also includes at least two elec ⁇ trodes 320, 322 for applying electric field across the Hquid crystal materials.
  • the electrode 320 preferably is in the form of a pluraUty of electrode strips 320a, 320b, etc. most clearly seen in Fig. 22.
  • the electrode 322 simUarly preferably is formed of a pluraUty of electrode strips 322a, 322b, etc., which are aligned paraUel with each other and in non-paraUel relation with respect to the electrode strips 320.
  • the electrode strips 320 are orthogonal with respect to the electrode strips 322, whereby at the area where respective electrode strips cross, a pixel or pixel-Hke area is defined therebetween.
  • the liquid crystal material of the device 300 located substantiaHy directly between the aligned portions of electrode strips 320a, 322a defines a pixel or pixel-Uke area that can effect coloring or filtering of Hght, on the one hand, or transmission of light on the other, without coloring the same.
  • the assemblage of pixels formed by the volumes of Uquid crystal and electrodes 320, 322 may be employed to form a Uquid crystal display capable of producing a particular optical or visuaUy perceivable output as a function of the prescribed inputs to the device 300.
  • a power supply and drive circuit 330 for example of conven ⁇ tional design, is associated with the Uquid crystal device 300 selectively to apply electric field of a prescribed type input, for example being able to alter voltage, frequency, and/or phase of appHed electric signal to respec ⁇ tive electrodes, or not to apply prescribed input to respective electrodes. Accordingly, under the energization of the power supply and drive circuit 330, and in cooperation therewith, the Hquid crystal device 300 is operative as an optical display device preferably capable to produce a multicolor output.
  • the power supply and drive circuit 330 may be of the type that produces electrical signals useful in a matrix addressing/multiplex scheme selectively to cause or not to cause responsive parallel aHgnment of Hquid crystal structure in respective volumes 306, 308 of Hquid crystal material 310, 312. Examples of such electrical signals and Hquid crystal driving technique are disclosed in the foUowing pubHshed articles: Paul R. Gerber, "Two-Frequency Addressing Of A Cholesteric Texture Change Electro- Optical Effect", AppHed Physics Letters, VoL 44, No.
  • various low frequency and high frequency signal portions of con- troUed amplitude for example as a function of actual power supply ampUtude and/or phase relation of signals, can be generated to effect the desired responsive alignment or not of Hquid crystal structure in respective volumes of Uquid crystal material in the Hquid crystal device 300.
  • Fig. 23 are illustrated a number of voltage waveforms used according to the matrix-addressing technique of Gerber.
  • Voltage waveform 332 has an ampUtude of 2Vg; and the voltage waveforms 334a, 334b, 334c have an amplitude of VQ.
  • Such voltage waveforms have both high frequency portions generaUy designated H and relatively low frequency portions generaUy designated L. The period of the high frequency portion H of each waveform, i.e.
  • the total time during which the high frequency portion is produced, and the voltage ampUtude VQ and 2Vn are selected such that appHcation of the voltage by a single one of such signals for that period or duration would not cause a change in the aHgnment of Hquid crystal structure; and the same is true for the relationship of the voltage VQ and period or duration of the low frequency portion L of each voltage waveforms 332 and 334.
  • the difference between the voltage waveforms 334a, 334b, 334c is in the phase relationship of the respective high and low frequency portions thereof to the phases of the high and low frequency portions of the waveform 332.
  • the high frequency portion of waveform 334a is 180° out of phase or phase reversed relative to the phase of the high frequency portion of the waveform 332; the low frequency portions of the waveforms or signals 334a, 332 are in phase.
  • the high frequency portions of the signals 334b and 332 are in phase; and the low frequency portions thereof are phase reversed, i.e. 180° out of phase.
  • the high frequency portion of the signals 334c, 332 are in phase, and the low frequency portions thereof also are in phase.
  • reference numeral 336 represents a row of pixels of the device 300, for example along the electrode strip 320a, that are unswitched due to the fact that no signal 332 is applied thereto. Such non- selected row is depicted at 336 with a pluraUty of unswitched pixel elements designated by the letter "u".
  • the device 300 and, accordingly, the Hne 336 may include more than the representatively depicted three pixels.
  • one of the signals 334 may be applied to one or more of the respective electrode strips of the electrode 322 that align with the electrode strip 320a of the pixel row 336, as was mentioned above, the ampUtude of the voltage 334 alone and the duration of the respective portions thereof preferably are inadequate to effect switching or alignment of Hquid crystal structure with respect to electric field between respective electrode strips.
  • Reference numeral 338 in Fig. 23 represents a row of pixels of the device 300 to which the signal 332 is appHed, for example the row of pixels aHgned with the electrode strip 320b.
  • Signals 334a, 334b, 334c may be delivered to respective electrode strips 322a, 322b, 322c, for example.
  • Pixels 340a, 340b, 340c of the device 300 are the ones represented in Hne 338 of Fig. 23.
  • the high frequency portions of the signals 332, 334a are out of phase; therefore, a high frequency voltage having an effective ampUtude of 3Vn is appHed to the pixel 340a.
  • the ampUtude 3VQ is adequate to align the structure of the non-cross over Hquid crystal material 312 in the volumes 308 with respect to the appHed electric field, thereby to minimize, preferably as close to zero as possible, any color fUtering by such Hquid crystal (and pleochroic dye contained therein).
  • the lower portion of such pixel is designated with a letter "s" indicating that such non-cross over Hquid crystal material is switched to aHgnment.
  • the frequency of such high frequency signal is above the cross over frequency of the cross over Hquid crystal material 310 in the volumes 306, and, therefore, the structure of such Uquid crystal and the pleochroic dye therein wiU aHgn normal to the applied field (the Hquid crystal then having negative dielectric anisotropy) or, in any event, generaUy wUl not be paraUel to such field. Therefore, the result of such volumes of cross over Hquid crystal material and pleochroic dye therein wiU be to cause color fUtering or coloring of light transmitted therethrough.
  • a letter "u" at pixel 340a in row 338 of Fig. 23 indicates the unswitched or in any event color filtering status of the cross over Hquid crystal material of the pixel.
  • both the cross over and non-cross over Hquid crystal materials 310, 312 in volumes 306, 308 wUl be switched to aHgn with the appHed electric field.
  • Such alignment is effected because the high frequency portions of the appHed signals are in phase and, therefore, have a net ampUtude of 2Vg, which is too smaU to effect alignment or dielectric anisotropy cross over.
  • pixel 340b provides minimal fUtering, preferably no fUtering, of Hght transmitted therethrough. Therefore, on Hne 338 in Fig. 23, both Hquid crystal materials are shown being switched, these conditions being repre ⁇ sented by the letter "s".
  • pixel 340c represented in Hne 338 of Fig.
  • the liquid crystal materials 310, 312 in volumes 306, 308 of such pixel are unswitched and effect fUtering of Hght transmitted therethrough as a function of the pleochroic dye in the respective Uquid crystal materials because the voltage waveform 334c (for example appUed to electrode strip 322c) has both high and low frequency portions that are in phase with the respective high and low frequency portions of the voltage waveform 332 appHed to electrode strip 320b.
  • the voltage waveforms for example 332, 334
  • the voltage waveforms may be of the type that are computer generated and/or computer controUed to achieve the desired frequencies and/or ampHtudes and, importantly, phase relationships. Addi- tionaUy, a further superimposed steady low-frequency voltage may be applied, as is described in the van Doom et al article mentioned above.
  • one or more of the signals 332, 334 may be turned on and off, and the responsive aHgnment of the one of the Hquid crystal materials, e.g. the cross over type, may be below that of such signal, thus enabUng either Hquid crystal material or both to be brought into responsive aHgnment (reduced color filtering), as is described generaUy above.
  • the power supply and drive circuit 330 is coupled to a pair of electrodes 320, 322 selectively to apply power to effect a discernible output from the Hquid crystal device 300.
  • Such device 300 is shown as two separate layers 302, 304 of volumes of Hquid crystal material.
  • the volumes of liquid crystal material may be arranged in the distributed form mentioned above, for example, with respect to Fig. 16.
  • the two-frequency phase shifting technique described with reference to the Uquid crystal device 300 of Figs. 21 and 22 may be used to apply electric field only to a single group or layer of volumes of cross over Hquid crystal material selectively to determine the optical properties thereof.
  • a separate voltage waveform or group of voltage waveforms may be used to provide electric field across a separate group or layer of volumes of liquid crystal material arranged in the layered fashion depicted particu ⁇ larly in Fig. 24.
  • a modified Hquid crystal device 300' is Ulustrated.
  • the device 300' is similar to the device 300 described above with reference to Figs. 21-23; in Fig. 24 parts designated by primed reference numerals correspond with parts designated by unprimed reference numerals in Fig. 21.
  • the primary difference between the device 300' and the device 300 is that the device 300' uses the electrodes 320', 322' to apply electric field only to the volumes 306' of cross over Hquid crystal material 310' in the layer 302'; and a further electrode 324 (preferably comprised of a pluraUty of electrode strips Hke the electrode 320' and arranged in crossed relation to the electrode strips of the electrode 322') cooperates with the electrode 322' to apply electric field to the volumes 308' of Hquid crystal material 312' in the separate layer 304'.
  • the electrode 322 is a shared one.
  • the power supply and drive circuit 330' may be substantiaUy the same as the circuit 330 providing appropriate output not only to drive respective pixels 340a', 340b', 340c' in the layer 302' but also to drive the remaining parts of such pixel-like areas in the layer 304*.
  • the power supply and drive circuit 330' would only have to apply DC voltage, low frequency voltage or high frequency voltage, or a combination thereof, of adequate ampUtude to effect switched aHgnment in paraUel with the electric field.
  • the electrode pair 320', 322' may be used to determine aHgned or not status of Hquid crystal material in layer 302' and the electrode pair 322', 324 may be used to determine the aHgnment condition of the Hquid crystal material in the layer 304'.
  • the electrode pair 320', 322', 324 may be used to determine the aHgnment condition of the Hquid crystal material in the layer 304'.
  • Uquid crystal device 300 is Ulustrated a further alternate embodiment of Uquid crystal device 300".
  • the elements designated by double primed reference numerals correspond generaUy to the elements identified by primed reference numerals or unprimed reference numerals in Figs. 21 and 24.
  • the Hquid crystal device 300" there are two layers 302", 304" of volumes 306", 308" of cross over liquid crystal material 310" and non-cross over Hquid crystal material 312", as is Ulustrated.
  • the Hquid crystal device 300' of Fig. 24 used a shared electrode 322'
  • the Hquid crystal device 300" uses respective dedicated electrodes 322a", 322b", which are separated by electrical insulation 341.
  • the power supply and drive circuit 330" provides voltage signals to the electrodes 320", 322a” in the manner described above with reference to Figs. 21-24, for example, using the two- frequency signal technique to cause aHgnment or non-aHgnment of Hquid crystal material in the layer 302".
  • the power supply and drive circuit 330" also provides voltage signals to electrodes 322b", 324" to determine the structural alignment of the Hquid crystal material in the layer 304". Since a separate electrode pair is used for each of the Hquid crystal layers in the device 300", the complexity of time multiplexed control of the power supply and drive circuit 330" may be less stringent than that required for the shared electrode arrangement of the device 300' and power supply and drive circuit 330' of Fig. 24. Operation of the device 300" generaUy foUows that described above with reference to the devices 300, 300' with respect to subtractive color operative principles.
  • the two- frequency energization technique may be used particularly advantageously with cross over Hquid crystal material.
  • the phase shifting technique for example using relatively low frequency signals, e.g. as in the low frequency portions of the signals 332, 334 of Fig. 23, may be used to effect selective alignment of liquid crystal structure of both cross over and non-cross over Hquid crystal materials in the various embodiments of Hquid crystal display disclosed herein.
  • One advantage of the just described operation of the Hquid crystal device is the abiUty to function turning liquid crystal material "on" and "off", i.e. aligned and non-aHgned, to effect specified optical results in response to phase variations in signals without having to apply and to remove a voltage. Rapid appHcation and/or removal of voltages can cause undesired transients; whereas the change in relative phase of one or more AC signals ordinarily would not result in such transients.
  • multiplex concepts hereof may be used in Hquid crystal devices that have more than two layers. For example, using a four layer device with six electrodes; namely, double the liquid crystal device 300, 300' of Figs. 21, 22 and 24 with both devices in optical serial relation to each other.
  • the device 342 there are a first pair of Uquid crystal layers 343, 344 with cross over Hquid crystal material therein and three electrodes 346, 348, 349 together with a power supply and drive circuit 330 as above.
  • the device 342 also includes a further Hquid crystal layer 350 (providing the third layer) that has non-cross over Hquid crystal therein.
  • the multiplex operation may be used for driving the first two layers with cross over Hquid crystal material therein while one of the signal electrodes proximate the third Uquid crystal layer and a fourth electrode 352, provide selective electric field or not to respective pixel-Hke areas of the third layer 350.
  • pixels of the third layer would be turned on or off by applying on the electrode 352 a signal similar to the signal 332, 334 but with both the low and high frequency components of the signal on the electrode 352 being either in phase or out of phase by 180° with the signal on such shared electrode 349.
  • Fig. 27 wherein parts similar to those Ulustrated in Fig.
  • a modified Hquid crystal device 342' includes a separate electrode 355 used with the third Hquid crystal layer 350 to cooperate with the electrode 352 to apply or not electric field to such third layer.
  • the electrode 355 may be separated from the electrode 349 by an insulator 356.
  • Fig. 27 the several parts correspond generaUy in form and function to the parts Ulustrated in Fig. 26.
  • the aforementioned multiplexing and/or frequency/phase shift ⁇ ing approach may be used selectively to provide prescribed input to plural volumes of different Hquid crystal distributed in a substantiaUy homogeneous layer, e.g. as is Ulustrated in Fig. 16.
  • the power supply and drive circuit 330 may provide respective signals 332, 334, for example to the electrodes 44, 46' of the liquid crystal display device 200 of Fig. 16 so as to cause paraUel alignment or not of the Hquid crystal in the respective volumes 202, 203.
  • appropriate magnitude of voltage and/or frequency of voltage may be appHed to respective pixel-like areas of the layer 201 to effect paraUel or non-paraUel aHgnment of the Hquid crystal material in respective volumes thereby to produce a selective color output.
  • the multiplexing tech ⁇ nique described herein provides for more than two frequency components in the respective signals, e.g. to accommodate multiple Hquid crystal materials that have different frequency threshold levels at which cross over of dielectric anisotropy occurs.
  • the signals 332, 334 may have a stiU higher frequency component than those Ulustrated in Fig. 23. Operation of such a Hquid crystal device with such relatively highest frequency component or term would be similar to the Uquid crystal device 300, for example, described above with reference to Fig. 21.
  • An exemplary circuit 360 in Fig. 28 may be used to develop the two-frequency signals of the articles mentioned above, for example with reference to the Uquid crystal devices 300, 300', 300" of Figs. 21-25.
  • the circuit 400 may be included as part of the power supply and drive circuits 330, 330', 330" to generate each signal appHed to a respective electrode 320, 322, 324, and so on.
  • circuit 360 there are low and high frequency circuit portions 361, 362, and a computer 363 controls signal generation and/or phase of each signal as weU as the time during which a given signal is delivered to a respective electrode.
  • a further multiplex circuit of conventional design may be used under control of the computer 363 selectively to couple the signal output on output Hne 364 to respective electrode strips.
  • a low frequency signal generator 366 such as a free running multivibrator, produces a low frequency signal of from several to several thousand Hz.
  • the frequency is below cross-over frequency of Hquid crystal material that may be used in a given display 300, for example.
  • the relative phase of such signal is determined by the phase control circuit 368 as determined by the computer 363.
  • the low frequency signal produced by the low frequency signal generator 366 is provided to a gate circuit 370 which passes such signal to output 364 when selected by a signal on Hne 372 from the computer.
  • Dotted Hne 374 indicates that the computer 363 may be coupled to one or more other low frequency circuit 361', which include(s) phase control, low frequency signal generator and gate to develop another low frequency signal for deHvery, say, to another electrode of a Hquid crystal device 300.
  • the low frequency signal on output 364 may be coupled to one of the strips of electrode 320 (Fig. 21) and the output from the other low frequency circuit may be coupled to a strip of electrode 322.
  • phase control the low frequency signal generator and gate
  • the low frequency signal on output 364 may be coupled to one of the strips of electrode 320 (Fig. 21) and the output from the other low frequency circuit may be coupled to a strip of electrode 322.
  • the high frequency circuit portion 362 of circuit 360 includes a high frequency signal generator 380, phase cpmtrp; 392. amd gate 384.
  • the high frequency portion is controUed by the computer 363, as is the low frequency portion, selectively to produce a relatively high frequency signal of a given phase on output 364.
  • the high frequency preferably is above the cross over frequency of cross over Hquid crystal material used in the display 300, for example.
  • Line 374 represents connection to another high frequency circuit portion 362' under control of computer 363 to develop a similar high frequency signal, for example.
  • the respective high frequency signals may be coupled to respective electrodes or electrode strips and may be con- troUed to have a particular phase relation to determine responsive aHgn ⁇ ment of Uquid crystal structure generaUy as was described above with reference to the devices 300, 300', 300".
  • a pixel 400 of a Hquid crystal display device 402 is Ulustrated.
  • the Uquid crystal device 402 has four Hquid crystal layers 404, 406, 408, 410 formed of volumes of operationaUy nematic Uquid crystal in a containment medium, with different respective pleochroic dyes in the liquid crystal of each layer.
  • the dyes may be cyan, yeUow, magenta and black.
  • a aprescribed input may be applied by a power supply 4U to the respective Hquid crystal layers using respective electrodes 412, 414, 416, 418, 420 in one of the various techniques described hereinabove, for example, to achieve aHgnment or not of the liquid crystal and dye in the respective volumes and layers thereby to absorb or to transmit light, generaUy as has been described in greater detaU elsewhere herein.
  • the black layer 410 gives saturation control independently of color.
  • the color layers 404, 406, 408 operate subtractively.
  • blackening i.e. black output or darkening of the output color Hght.
  • the black layer is field off/distorted, there is a large amount of blackening, i.e. black output or darkening of the output color Hght.
  • the black layer is field off, then a black output is produced. If aU the colors are on and the black also is on, then the output wiU be white or in any event generaUy the color of the Uluminating source 422.
  • the black layer 410 controls the brightness of light transmitted through the device.
  • the electrodes may be formed in layers on transfer sheets that are appHed directly to the Hquid crystal layers.
  • the electrodes of each layer would be a plurality of electrode strips arranged in a crossed pattern to define individual pixel areas, for example as is represented at 400 of the Hquid crystal display device 402, at each crossing of a respective pair of electrode strips.
  • Transmissive white is achieved in the embodiment of the inven ⁇ tion depicted in Fig. 29, for example.
  • Specif icaUy with aU Hquid crystal layers 404, 406, 408, 410 in field on condition, then the Hght transmitted is white, or in any event the color of the iUuminating source.
  • This relatively pure white may be contrasted with an RGB (red, green, blue color) system in which the colors are additive.
  • RGB red, green, blue color
  • aU three color red, green and blue color dots adjacent each other must be turned "on" to achieve the reflective function; but this results in only about 1/3 the brightness of a transmissive system because the three colors must be added to achieve a white output.
  • the Hquid crystal color layers 404, 406, 408 in the display device 402 use Hquid crystal material that has a low delta-N (i.e. birefringence) to achieve bright colors.
  • the reason is to avoid scattering light when the Uquid crystal material is in distorted alignment, for such scattering would tend to decrease resolution. Scattering the colors would tend to muddy the colors. Therefore, preferably the color output of each of such Hquid crystal color layers preferably would be achieved using pleo ⁇ chroic dye in the Uquid crystal material; and the Uquid crystal material would be used primarily as a switch perhaps with some degree of analog characteristics to turn on, off or partly on or off the dye coloring effect.
  • the black Hquid crystal layer 410 preferably should have a relatively high delta-N (birefringence) to give better control of intensity.
  • delta-N birefringence
  • the delta-N for the black layer could be any value and stiU work, it is beHeved best when relatively high for maximum black effect because the larger the difference between extraordinary index of refraction of the Uquid crystal and containment medium thereof, the more scattering of Ught occurs and the greater the path length of light through the black dye.
  • a pixel 400' of a Uquid crystal display device 402' is Ulustrated.
  • parts corresponding to the pixel 400 described above with reference to Fig. 29 are designated with the same reference number carrying a prime designation, e.g. 400'.
  • the dye in the Hquid crystal layer most Hkely to be closest to exposure to ultraviolet radiation e.g. the layer 404'
  • This layer 404' then protects the other Hquid crystal color layers 406', 408', 410 1 from ultraviolet radiation. It is known that ultraviolet radiation can cause degradation of pleochroic dye; and, therefore, the present invention provides for increased protection to avoid such degradation.
  • both pleochroic dye and non-pleochroic dye coloring functions may be combined in a single liquid crystal display device 430 Ulustrated in Fig. 31.
  • the individual pixel-like areas of the various Uquid crystal color display devices hereof may be relatively smaU and so closely positioned as to effect an additive color function of the type found in RGB color systems, for example.
  • Such additive operation may be employed in the Hquid crystal color display device 430, for example depending on the color dyes used and the pixel sizes.
  • the device 430 may be used more on a macro size basis to display colors over relatively large areas not intended to undergo additive function.
  • the Hquid crystal color display 430 includes a layer 432 of plural volumes 434 of operationaUy nematic Uquid crystal 436 in a containment medium 438. Electrodes 440, 442 are provided to apply electric field to layer 432 or to parts thereof, for example using one of the above-described techniques. The electrodes may be strip electrodes, soHd electrodes, etc.
  • a power supply 444 provides appropriate electric field signals to the Hquid crystal layers or parts thereof selectively to effect paraUel aHgnment of the liquid crystal with the electric field or possibly to force non-alignment if cross over liquid crystal material is used, as was described above. More ⁇ over, a light source 446 provides Ught for transmission through the device 430.
  • Pleochroic dye 450 is contained in plural volumes of Hquid crystal 436 to function in guest host relation, whereby the dye structure foUows the liquid crystal structure so as to absorb or to color Ught when distorted or not aHgned generaUy in paraUel with an appHed electric field or generally with respect to the direction of propagation of Hght therethrough. Moreover, the amount of such absorption or coloring wiU reduce when the dye structure aHgns in the direction of light propagation, e.g. when the liquid crystal structure is similarly aHgned particularly generaUy in paraUel with an appHed electric field.
  • the liquid crystal color display 430 also includes non-pleochroic dye 452.
  • non-pleochroie dye may also be in the Uquid crystal volumes, but preferably such non-pleochroic dye is in the contain ⁇ ment medium 438.
  • Both possibiUties are disclosed in appUcanfs above- mentioned U.S. Patent Application Serial No. 480,466.
  • the non-pleochroic dye 452 may be added to the containment medium 438 or Uquid crystal during the process of forming the same the volumes of Uquid crystal, e.g. as a part of an emulsion of the Hquid crystal material and containment medium.
  • the non-pleochroic dye may be appHed by imbibition using the techniques disclosed in appHcant's above-mentioned U.S. Patent Application Serial No. 480,461.
  • the Hquid crystal color display device 430 In operation of the Hquid crystal color display device 430, when no field or other appropriate prescribed input is appHed, the Hquid crystal structure is distorted and both the pleochroic due 450 and the non- pleochroic dye wiU tend to absorb, fUter or color light incident thereon from the source 458.
  • an appropriate prescribed input e.g., an electric field
  • the Hquid crystal structure aligns with respect to the field, and the coloring effect of the pleochroic dye is reduced; however, the coloring effect of the non- pleochroic dye continues.
  • both dyes impact on the light transmitted through the device 430; in the on condition of the Uquid crystal material, only the non-pleochroic dye wiU have impact.
  • the pleochroic dye and the non-pleochroic dye may be selected to cooperate with each other to produce color outputs not heretofore possible using pleochroic dye alone.
  • the pleochroic dye and the non-pleochroic dye may be selected to be complementary colors so that when both are acting to color light, the effect is black.
  • the output effect is the color of the non-pleochroic dye.
  • Exemplary complementary colors would be a magenta pleochroic dye and a green non-pleochroic dye.
  • the pleochroic dye can serve as a switch for the non-pleochroic dye coloring function. More generaUy, the pleochroic dye can serve as a switch for turning on or black an output from the device 430. Specif icaUy, no Ught output or black would be produced in the absence of a prescribed input; a particular color output would be produced in the presence of the prescribed input.
  • a multicolor display device can be made by employing in different pixel-Hke areas of the device 430 different respective color dyes, both pleochroic and non-pleochroic, of different respective complementary color pairs.
  • the result is a multicolor display device of the type depicted generaUy in Fig. 10 for use, say, in a color television or like device.
  • the display device 430 just described provides in a single Uquid crystal device of pixel-Hke size or area or larger size, multiple functions of coloring light and of switching a light output on and off. Indeed, such functions are accompHshed according to the invention in a single layer device, as is Ulustrated in Fig. 31 and is described above.

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  • Nonlinear Science (AREA)
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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mathematical Physics (AREA)
  • Engineering & Computer Science (AREA)
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  • Liquid Crystal (AREA)

Abstract

Un affichage couleur à cristaux liquides (20) fournit une sortie de lumière transmise d'une ou de plusieurs couleurs, noir et/ou blanc, en fonction d'une lumière incidente et d'une excitation commandée ou non de couches couleurs de cristaux liquides respectives positionnées optiquement et en série (2, 3, 4) et/ou d'une couche ou de couches couleurs de cristaux liquides composites multicolores dans l'affichage. Plusieurs volumes disposés optiquement et en série (21) d'un matériau de cristaux liquides nématiques (25) ayant des caractéristiques optiques différentes, par exemple teintés avec des colorants pléochroïques différents (28) peuvent être alignés sélectivement ou non par rapport à un champ électrique pour déterminer la sortie optique du dispositif dans un mode couleur soustractif. Des techniques de discrimination d'une tension et/ou d'une fréquence permettent d'obtenir une réponse multicolore en utilisant uniquement une seule paire d'électrodes (45, 46, 47). En utilisant des cristaux liquides croisés ayant des caractéristiques d'anisotropie diélectrique positive et négative en fonction de la fréquence du signal appliqué, la commande multiplexe de l'affichage à cristaux liquide est facilitée.
PCT/US1986/001863 1985-03-01 1986-09-10 Procede et affichage couleur a cristaux liquides WO1988002128A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
PCT/US1986/001863 WO1988002128A1 (fr) 1985-03-01 1986-09-10 Procede et affichage couleur a cristaux liquides
US06/942,548 US4878741A (en) 1986-09-10 1986-09-10 Liquid crystal color display and method
CA000546445A CA1291552C (fr) 1985-03-01 1987-09-09 Affichage polychrome a cristal liquide, et methode connexe

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US70748685A 1985-03-01 1985-03-01
PCT/US1986/001863 WO1988002128A1 (fr) 1985-03-01 1986-09-10 Procede et affichage couleur a cristaux liquides

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0346911A1 (fr) * 1988-06-16 1989-12-20 Canon Kabushiki Kaisha Milieu d'affichage, procédé et dispositif d'affichage
EP0435676A3 (en) * 1989-12-28 1992-04-29 Sharp Kabushiki Kaisha Liquid crystal display device for displaying multiple or full colors
EP0426291A3 (en) * 1989-10-31 1992-06-17 University Of Hawaii Colour liquid crystal display
EP0543658A3 (en) * 1991-11-21 1993-11-03 Fujitsu Ltd Liquid-crystal color display device
GB2287096A (en) * 1994-02-25 1995-09-06 Secr Defence Electro-optic colour device
US5570210A (en) * 1993-05-06 1996-10-29 Fujitsu Limited Liquid crystal display device with directional backlight and image production capability in the light scattering mode
WO1999005564A1 (fr) * 1997-07-25 1999-02-04 Eveready Battery Company, Inc. Affichage a cristaux liquides et etiquette de pile comportant un affichage a cristaux liquides
US6156450A (en) * 1997-07-24 2000-12-05 Eveready Battery Company, Inc. Battery tester having printed electronic components

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4401537A (en) * 1978-12-26 1983-08-30 Minnesota Mining And Manufacturing Company Liquid crystal display and photopolymerizable sealant therefor
US4470668A (en) * 1981-04-28 1984-09-11 Ricoh Company, Ltd. Reaction setting, polymer, sealing material for liquid crystal displays

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4401537A (en) * 1978-12-26 1983-08-30 Minnesota Mining And Manufacturing Company Liquid crystal display and photopolymerizable sealant therefor
US4470668A (en) * 1981-04-28 1984-09-11 Ricoh Company, Ltd. Reaction setting, polymer, sealing material for liquid crystal displays

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5066107A (en) * 1988-06-16 1991-11-19 Canon Kabushiki Kaisha Liquid crystal display medium, liquid crystal display method and liquid crystal display apparatus for outputting color images
EP0346911A1 (fr) * 1988-06-16 1989-12-20 Canon Kabushiki Kaisha Milieu d'affichage, procédé et dispositif d'affichage
EP0426291A3 (en) * 1989-10-31 1992-06-17 University Of Hawaii Colour liquid crystal display
EP0435676A3 (en) * 1989-12-28 1992-04-29 Sharp Kabushiki Kaisha Liquid crystal display device for displaying multiple or full colors
EP0543658A3 (en) * 1991-11-21 1993-11-03 Fujitsu Ltd Liquid-crystal color display device
US5317431A (en) * 1991-11-21 1994-05-31 Fujitsu Limited Liquid crystal display device with scattering white layer and color filter
US5570210A (en) * 1993-05-06 1996-10-29 Fujitsu Limited Liquid crystal display device with directional backlight and image production capability in the light scattering mode
GB2287096A (en) * 1994-02-25 1995-09-06 Secr Defence Electro-optic colour device
US5760860A (en) * 1994-02-25 1998-06-02 The Secretary Of State For Defense In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland Electro-optic scattering type devices with color polariser for switchable color
US6156450A (en) * 1997-07-24 2000-12-05 Eveready Battery Company, Inc. Battery tester having printed electronic components
WO1999005564A1 (fr) * 1997-07-25 1999-02-04 Eveready Battery Company, Inc. Affichage a cristaux liquides et etiquette de pile comportant un affichage a cristaux liquides
US6154263A (en) * 1997-07-25 2000-11-28 Eveready Battery Company, Inc. Liquid crystal display and battery label including a liquid crystal display
US6307605B1 (en) 1997-07-25 2001-10-23 Eveready Battery Company, Inc. Liquid crystal display and battery label including a liquid crystal display

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