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EP1436359A1 - Afficheur a cristaux liquides dote d'un polariseur reflechissant - Google Patents

Afficheur a cristaux liquides dote d'un polariseur reflechissant

Info

Publication number
EP1436359A1
EP1436359A1 EP02761772A EP02761772A EP1436359A1 EP 1436359 A1 EP1436359 A1 EP 1436359A1 EP 02761772 A EP02761772 A EP 02761772A EP 02761772 A EP02761772 A EP 02761772A EP 1436359 A1 EP1436359 A1 EP 1436359A1
Authority
EP
European Patent Office
Prior art keywords
display according
region
spectrum
foregoing
polarizer
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP02761772A
Other languages
German (de)
English (en)
Inventor
Pavel Lazarev
Michael Paukshto
Ma Yao-Dong
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nitto Denko Corp
Original Assignee
Optiva Inc
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
Priority claimed from RU2001125727/28A external-priority patent/RU2226708C2/ru
Application filed by Optiva Inc filed Critical Optiva Inc
Publication of EP1436359A1 publication Critical patent/EP1436359A1/fr
Withdrawn legal-status Critical Current

Links

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
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G02F1/133536—Reflective polarizers
    • 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
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G02B5/3041—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks
    • G02B5/305—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid comprising multiple thin layers, e.g. multilayer stacks including organic materials, e.g. polymeric layers

Definitions

  • the present invention relates generally to devices of displaying information, and in particular to liquid crystal displays (LCDs).
  • LCDs liquid crystal displays
  • a cuvette is usually formed by two parallel glass plates, on the inner sides of which are electrodes made from optically transparent conducting materials, and alignment layers.
  • the cuvette is filled with a liquid crystal material which forms a layer having thickness ranging from 5 to 20 ⁇ m.
  • the liquid crystal material is an active medium that changes its optical properties such as angle of rotation of polarization plane under the influence of an electric field. Variations of optical properties are viewed in the crossed polarizers, which are usually glued on the external surfaces of the cuvette.
  • the areas of the display where electrodes are not electrically charged transmit light and look bright, while the areas under voltage look dark (L.K. Vistin. JVHO, 1983, vol. XXVII, ed. 2, pp.141-148).
  • a mirror or reflector is provided behind the LC cuvette so that the incident light passes through the cuvette twice. Formation of an image is performed analogously to the transmission displays (Pochi Yeh, Claire Gu, Optics of liquid Crystal Displays, N. - Y., 1999, p.p.233-237).
  • the main drawback of traditional displays is the small observation angle since lights propagate towards the front surface of the multiplayer LC display only within the limits of a confined cone angle.
  • Such displays usually use absorbing polarizers based on a polymer such as polyvinyl alcohol having optical anisotropy, which can be obtained via monoaxial stretching of the film of this polymer as described in U.S. Patent No. 5,007,942, and subsequent dyeing of the film in iodine fumes or in an organic dye.
  • the ellipsoids of angular dependence of the real and imaginary parts of refraction index of the polarizer have stretched-out (needle-like) shape.
  • the traditional displays also have relatively low brightness, low contrast and high power consumption due to the large number of absorbing layers.
  • Color displays usually have the same design wherein color filters are used. Each pixel of a color image is formed via mixing of three colors (red, blue and green) in a proper ratio (Nikkei Electronics, 1983,5-23, p.p. 102 - 103). Using absorbing filters may cause additional light losses in the device and as a consequence increase energy consumption.
  • LC displays where the polarizer layer is obtained from aligned supramolecular complexes of a dichroic dye.
  • Such polarizers have high optical characteristics and small thickness, which allows their placement inside the display. This simplifies the design and increases durability of the display.
  • the fabrication technology of such layers allows combining several functions in a single layer (for example polarizing and LC aligning) (RU 2120651, 15.04.96).
  • WO 99/31535 describes a LC indicatory element which incorporates a polarizer containing a birefringent anisotropically absorbing layer having a refraction index that increases with the increase of the wavelength of incident light.
  • a polarizer may be obtained from LLC dichroic dye and may have certain thickness to establish interference extremum on at least one side of the polarizer.
  • the above noted patent application also describes a reflecting polarizer.
  • One of the drawbacks of using such polarizers for color display is that they reflect light in a wide spectral range which leads to smeared colors.
  • further development of display technology requires better optical characteristics of polarizing elements, particularly increased viewing angle at which there is an efficient light transformation.
  • one object of the present invention is to provide a display that has increased display brightness, spectrally clean color images, and is capable of creating white, black and color components in an image to increase the contrast and richness of the image, and has increased observation angle of the display.
  • the liquid crystal display of the present invention which comprises front and rear panels, and electrodes, polarizers and a layer of liquid crystal disposed between the front and rear panels.
  • the polarizer on the rear panel is preferably a reflecting type in at least one region of spectrum and contains at least one element in form of a multilayer structure.
  • the multilayer structure contains at least two anisotropic layers separated by at least one intermediate layer which is optically transparent in the desired spectral region.
  • the ratio of refraction indices and thickness of the layers in the multilayer structure is chosen such to provide an extremum for the ratio of transmitted and reflected polarized lights in the spectral region.
  • Figure 1 is a schematic sectional view of a liquid crystal display having internal polarizers according to one embodiment of the present invention.
  • Figure 2 is a partial sectional view of the liquid crystal display of FIG. 1 showing the details of a multilayer reflecting polarizer.
  • Figure 3 is a graph illustrating spectral characteristics of the liquid crystal display according to one embodiment of the present invention.
  • the LC display of the present invention shown in Fig.1 includes front and rear panels 1 and 2 with functional layers such as electrodes, polarizing layer, adhesion layer and a layer of liquid crystal 3 disposed between the front and rear panels.
  • On the inner side of the front panel 1 is a thin crystalline film 4 functioning as a dichroic polarizer.
  • the crystalline film 4 may be formed according to the method described below from LLC containing 12.5% mixture of dyes (Vat Blue 4; bis-benzimidazole-[2,l-a:r2 ⁇ b , ]anthra[2,l,9-def:6,5,10- dVf]diisoquinoline-6,9-dion; Vat Red 15 in the ratio 5.2 : 2 : 1).
  • the LLC is transferred into an insoluble form after being treated with Barium ions.
  • the thickness of the crystalline film 4 is about 100 nm. Since the crystalline film 4 is a highly ordered anisotropic film, it may simultaneously work as an alignment layer for the LC display.
  • the reflecting polarizer 5 On the internal surface of the rear panel 2 is provided a reflecting polarizer 5 have a multilayer structure.
  • the rear panel 2 is also provided with an absorbing layer 6 on the outer surface of the rear panel 2.
  • the reflecting polarizer 5 consists of three layers as shown in Fig. 2: starting from the rear panel 2 of the display, a crystalline layer 7 obtained from LLC of dye Vat Red 15, which is about 60nm thick, an isotropic transparent layer 8 of polyvinylacetate, which is about lOOnm thick, and a crystalline layer 9 obtained from LLC of dye Vat Red 15, which is about 60nm thick. Crystalline layers 7 and 9 are distinct by their high degree of anisotropy: in the wavelength interval 570 - 600 nm it reaches 0.8.
  • Reflecting polarizer 5 has integral reflecting efficiency of about 44% of polarized light for extraordinary direction and about 1% for ordinary direction.
  • Figure 3 shows corresponding spectral characteristics of the reflected light for different directions of polarization.
  • the display features bright images, rich color (green), high contrast and wide observation angle.
  • At least one anisotropic layer of the multilayer structure 5 is optically transparent in the mentioned region of spectrum for both components of polarization. It is preferred that at least one anisotropic layer has degree of anisotropy no less than
  • At least one anisotropic layer of the multilayer structure 5 is a polarizer of E-type in at least one region of the spectrum.
  • the anisotropic layers are usually obtained from at least one organic dye and/or derivatives thereof, which are capable of forming lyotropic liquid crystal (LLC).
  • LLC lyotropic liquid crystal
  • At least one of the polarizers is disposed between the front and rear panels of the display.
  • an absorbing layer 6 absorbing in at least the desired spectrum region or in the entire visible wavelength range is provided on the outer surface of the rear panel 2 along the direction of the incident light.
  • At least one anisotropic layer in the display is at least partially crystalline.
  • the polarizer 5 on the rear panel 2 preferably consists of a matrix of color reflecting elements, each of which reflects in at least one region of the spectrum.
  • the choice of matrix elements is governed by the conditions to provide a set of basic colors.
  • the basic colors are blue with wavelength in the range 400-500 nm, green with wavelength in the range 500-600 nm and red with wavelength in the range 600-700 nm.
  • the absorbing layer 6 disposed on the rear panel 2 and consisting of a matrix of colored reflecting elements absorbs in the entire visible wavelength range.
  • the display includes white, black and colored components in the color image.
  • the LC display according to the present invention contains front and rear panels, and electrodes, polarizers and other functional layers, and a layer of liquid crystal between the front and rear panels.
  • the polarizer on the front panel is preferably neutral, transmitting one polarized component of light and efficiently absorbing the other.
  • the polarizer on the rear panel in a monochromatic display represents a multilayer structure containing at least two optically anisotropic layers separated by an optically transparent intermediate layer. The thickness and refraction indices of all layers are selected such that the polarizer efficiently reflects radiation of one polarization in certain region of the spectrum and transmits orthogonally polarized radiation, which is later absorbed by the filters.
  • the polarizer on the rear panel represents a matrix of color reflecting elements, each of which is implemented analogously to the reflecting polarizer described above for the monochromatic display.
  • the choice of matrix elements is governed by the condition to provide a set of basic colors in the image. In order to obtain spectrally clean, high contrast color images, it is preferred that each matrix element reflects in a narrow spectral range.
  • the multilayer structure 5 it is preferably to obtain homogeneous layers with high degree of anisotropy, high value of one of the refraction indices and preferably thin (comparable to the wavelength).
  • Crystalline films or layers obtained according to methods of Optiva Technology (Lazarev P., Paukshto M., Proceeding of the 7 th International Display Workshops, Materials and Components, Kobe, Japan, November 29 - December 1 (2000), p.p. 1159 - 1160) can be used in fabrication of the multiplayer structure 5.
  • Suitable organic materials include indanthrone (Vat Blue 4), dibenzoimidazol 1,4,5,8-naphthalenetetracarboxilic acid (Vat Red 14), dibenzoimidazole 3,4,9, 10-perylentatracorboxilic acid, quinacridone (Pigment Violet 19), their derivatives, and any combination thereof.
  • LC liquid crystal solution
  • the method of preparing thin anisotropic crystalline films from the colloid system with supramolecular complexes involves the following steps:
  • the colloid system possesses thixotropic properties for which the colloid system must be at a certain temperature and have certain concentration of the dispersion phase;
  • any suitable external impact to provide a decreased viscosity of the system (this may be heating, deformation by shearing etc.).
  • the external impact may continue during the entire subsequent process of alignment or have the necessary duration so that the system does not return to a state with increased viscosity during alignment;
  • an external orienting force on the system which may be implemented mechanically as well as with any other method.
  • the force must be sufficient so that the kinetic units of the colloid system receive necessary orientation and form the structure, which will be the basis for the future crystal lattice in the resulting layer;
  • planes of molecules are parallel to each other and so form three-dimensional crystal in at least a part of the layer.
  • monocrystalline layers can be obtained.
  • Optical axis in such crystal will be perpendicular to the planes of molecules.
  • Such layer will possess high degree of anisotropy and high refraction index for at least one direction.
  • the thickness of the layer usually does not exceed l ⁇ m.
  • the thickness of the resulting film may be controlled through the content of the solid phase in the original LC and the thickness of the deposited layer of LLC.
  • a mixture of colloid systems may be used (in this case there will be combined supramolecular complexes formed in solution).
  • Absorption and refraction may have various values within the limits determined by the original components in the layers obtained from mixtures of colloid solutions. Mixing various colloid systems and obtaining combined supramolecular complexes is possible due to the flatness of molecules (or their fragments) and coincidence of one of the dimensions of molecules from the above-mentioned organic compounds (3.4A).
  • molecules In the wet layer, molecules have good order along one direction due to orientation of supramolecular complexes on the substrate. During evaporation of the solvent, it appears more energetically favorable for the molecules to form three-dimensional crystalline structure.
  • the multilayer structure includes at least two anisotropic layers obtained by the above described method. Here, optical axes of separate anisotropic layers are usually co- directional.
  • Reflection of light in certain spectral ranges by the polarizer may occur due to interference effect in the thin layers.
  • the thickness of the layers and refraction indices for each direction of polarization is selected such that one polarization component of light will be efficiently reflected by this structure while the other will pass through without being reflected.
  • a layer of an all- absorbing material is provided on the outer surface of the rear panel along the direction of radiation propagation. This eliminates glare from the rear panel of the display and enhances contrast of the image.
  • such design allows obtaining black color in the image. Since obtained layers are thin (less than 100 nm) and the number of layers may be minimal (e.g. 3) due to high degree of anisotropy, such multilayer structure may be placed inside of the LC display.
  • the polarizer for the front panel may also be obtained according to the above described technology with corresponding choice of the organic materials, which forms LLC, or a mixture of materials having suitable absorption spectra. Moreover, this polarizer may also be placed inside the display.
  • the inventive method of fabricating anisotropic layers is based on the fact that ellipsoids of angular dependence of real and imaginary parts of the refraction index have disk-like shape. Changing the shape of the ellipsoids of the imaginary part of the refraction index significantly improves the parameters of the polarizer and its angular characteristics. Using such polarizers in a display can increases observation angle practically up to 180°.
  • the polarizer on the rear panel of a color display, representing a matrix of color reflecting elements may also be obtained according to the above described technology, for example, using masks to form local coatings.
  • layers of anisotropic materials are deposited sequentially one after the other according to the above described technology.
  • the coating material is transfe ⁇ ed into the insoluble form.
  • the rest of the area is cleaned via rinsing.
  • Another layer of an anisotropic material is deposited on the top of the resulting layer, and the procedure is repeated. If needed, additional polarizing layers may be used.
  • the multilayer structure of the polarizer which is the matrix of separate elements, is formed. Each element of the matrix reflects light of certain spectral range and one polarization.

Landscapes

  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Nonlinear Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mathematical Physics (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Liquid Crystal (AREA)
  • Polarising Elements (AREA)

Abstract

Afficheur à cristaux liquides qui possède des panneaux avant et arrière, des électrodes, des polariseurs et une couche de cristaux liquides placée entre les panneaux avant et arrière. Le polariseur situé sur le panneau arrière est de préférence du type réfléchissant dans au moins une plage du spectre et contient au moins un élément sous forme de structure multicouche. Ladite structure multicouche contient au moins deux couches anisotropiques séparées par au moins une couche intermédiaire qui est optiquement transparente dans la plage spectrale désirée. Le rapport des indices de réfraction et de l'épaisseur des couches dans la structure multicouche est choisi de manière à fournir un rapport maximal de la lumière polarisée transmise et réfléchie dans la plage spectrale.
EP02761772A 2001-09-21 2002-09-20 Afficheur a cristaux liquides dote d'un polariseur reflechissant Withdrawn EP1436359A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
RU2001125727/28A RU2226708C2 (ru) 2001-09-21 2001-09-21 Жидкокристаллический дисплей с отражающим поляризатором
RU2001125727 2001-09-21
US241068 2002-09-10
US10/241,068 US6847420B2 (en) 2001-09-21 2002-09-10 Liquid crystal display with reflecting polarizer
PCT/US2002/030008 WO2003025092A1 (fr) 2001-09-21 2002-09-20 Afficheur a cristaux liquides dote d'un polariseur reflechissant

Publications (1)

Publication Number Publication Date
EP1436359A1 true EP1436359A1 (fr) 2004-07-14

Family

ID=26654094

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02761772A Withdrawn EP1436359A1 (fr) 2001-09-21 2002-09-20 Afficheur a cristaux liquides dote d'un polariseur reflechissant

Country Status (4)

Country Link
EP (1) EP1436359A1 (fr)
JP (1) JP4201267B2 (fr)
CN (1) CN100403108C (fr)
WO (1) WO2003025092A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2226708C2 (ru) 2001-09-21 2004-04-10 ОПТИВА, Инк. Жидкокристаллический дисплей с отражающим поляризатором
JP5205747B2 (ja) 2006-12-08 2013-06-05 ソニー株式会社 液晶表示装置および投射型表示装置
CN103969882B (zh) * 2014-04-23 2016-07-06 京东方科技集团股份有限公司 一种液晶面板及显示装置

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0246842B1 (fr) * 1986-05-19 1998-09-23 Seiko Epson Corporation Dispositif d'affichage à cristal liquide
JPH04161978A (ja) * 1990-10-24 1992-06-05 Nippon Paint Co Ltd カラー液晶表示装置
JP3044681B2 (ja) * 1994-06-08 2000-05-22 富士写真フイルム株式会社 液晶表示装置
RU2120651C1 (ru) * 1996-04-15 1998-10-20 Поларайзер Интернэшнл, ЛЛСи Жидкокристаллический индикаторный элемент
US6122079A (en) * 1997-02-28 2000-09-19 Polaroid Corporation Chromatically-adjusted holographically illuminated image-providing display element
RU2124746C1 (ru) * 1997-08-11 1999-01-10 Закрытое акционерное общество "Кванта Инвест" Дихроичный поляризатор
US6767594B1 (en) * 1997-12-16 2004-07-27 Gosudarstvenny Nauchny Tsentr Rossiiskoi Polarizer and liquid crystal display element
US6207260B1 (en) * 1998-01-13 2001-03-27 3M Innovative Properties Company Multicomponent optical body

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO03025092A1 *

Also Published As

Publication number Publication date
WO2003025092A1 (fr) 2003-03-27
CN1575329A (zh) 2005-02-02
CN100403108C (zh) 2008-07-16
JP2005504331A (ja) 2005-02-10
JP4201267B2 (ja) 2008-12-24

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