WO2009051408A1 - Procédé de fabrication de polariseur réfléchissant cholestérique à lame quart d'onde, et son polariseur réfléchissant - Google Patents

Procédé de fabrication de polariseur réfléchissant cholestérique à lame quart d'onde, et son polariseur réfléchissant Download PDF

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Publication number
WO2009051408A1
WO2009051408A1 PCT/KR2008/006085 KR2008006085W WO2009051408A1 WO 2009051408 A1 WO2009051408 A1 WO 2009051408A1 KR 2008006085 W KR2008006085 W KR 2008006085W WO 2009051408 A1 WO2009051408 A1 WO 2009051408A1
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WO
WIPO (PCT)
Prior art keywords
liquid crystal
crystal layer
nematic liquid
cholesteric liquid
resins
Prior art date
Application number
PCT/KR2008/006085
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English (en)
Inventor
Yong-Shig Shim
Dong-Woo Lee
Hyung-Jun Kwon
Chul-Ki Kim
Jung-Ae An
Original Assignee
Lms Co., Ltd.
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Filing date
Publication date
Application filed by Lms Co., Ltd. filed Critical Lms Co., Ltd.
Publication of WO2009051408A1 publication Critical patent/WO2009051408A1/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
    • G02F1/133—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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00634—Production of filters
    • B29D11/00644—Production of filters polarizing
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3083—Birefringent or phase retarding elements
    • 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
    • G02F1/1303—Apparatus specially adapted to the manufacture of LCDs
    • 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
    • G02F1/13718—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 a change of the texture state of a cholesteric liquid crystal
    • 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
    • G02F1/133543—Cholesteric polarisers
    • 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
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G02F1/133638—Waveplates, i.e. plates with a retardation value of lambda/n
    • 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
    • G02F2202/00—Materials and properties
    • G02F2202/02—Materials and properties organic material
    • G02F2202/022—Materials and properties organic material polymeric
    • G02F2202/023—Materials and properties organic material polymeric curable

Definitions

  • the present invention relates to manufacture of a reflective polarizer film used in an
  • a Liquid Crystal Display typically has two glass plates on each of which a transparent electrodes is formed, a liquid crystalline material sandwiched between the glass plates and front and rear polarizer films, with the front polarizer film arranged in the front and the rear polarizer film arranged in the rear of the glass plates.
  • a polarizer film used in the LCD is manufactured by stretching a polyvinyl alcohol film, on which iodine (I) or dichromatic dye is adsorbed, in a predetermined direction.
  • the polarizer film manufactured as above realizes light of linear polarization by absorbing light vibrating in one direction but allowing light vibrating in the other direction to pass through.
  • a polarizer having a theoretic efficiency not exceeding 50% becomes a main factor decreasing the efficiency of an LCD.
  • the absorbing of light causes other problems in the LCD. That is, when a light source is powered up to a predetermined level or more, the polarizer is broken by heat caused by thermal conversion of the absorbed light, or display quality is degraded due to thermal effect to the liquid crystal layer inside a cell.
  • cholesteric liquid crystal having a circular polarization- separating function as a reflective polarizer has been proposed.
  • the cholesteric liquid crystal selectively reflects light of circular polarization when the direction of the circular polarization is identical with the helical-rotation direction of the liquid crystal and the wavelength of the circular polarization is identical with the spiral pitch of the liquid crystal.
  • the selective reflection characteristic of the cholesteric liquid crystal makes it possible to produce a high efficiency polarizer film that can filer and separate circular polarization from natural light in a predetermined wavelength range and reuse other portions of the light.
  • a high transmittance LCD can be obtained by converting the transmissive circular polarization into linear polarization by allowing the transmissive circular po- larization to pass through a ⁇ /4 wavelength plate and setting the direction of the linear polarization to be identical with the transmission direction of an absorptive polarizer used in an LCD. Since a linear polarizer obtained by combining a cholesteric liquid crystal film with the ⁇ /4 wavelength plate theoretically has no light loss, it is theoretically possible to double brightness compared to the case where the conventional absorptive polarizer is used alone.
  • Conventional approaches using the cholesteric liquid crystal may include methods of manufacturing a broadband cholesteric liquid crystal film, which has a visible light range as a selective reflection wavelength range (e.g., Korean Patent Application Nos. 10-1998-0000498, 10-1999-0065640, 10-2004-0078416 and 10-2004-0060853).
  • the broadband cholesteric liquid crystal film is manufactured by adhering and stacking cholesteric liquid crystal films, each of which has a selective reflection function due to parallel orientation, with one atop each other from shorter to longer wavelengths.
  • the cholesteric liquid crystal film is stacked via a bonding layer and a cholesteric liquid crystal polymer layer is simply stacked, at least three (3) layers are used to cover the entire visible light range increase the thickness. Different refractive indices of the bonding also interface increase reflection loss.
  • a polarizer which includes a circular polarization-separating layer with a helical pitch changing in the thickness direction and a phase difference layer located in a long wavelength side of the central wavelength of reflecting light, byclosely stacking two or more cholesteric liquid crystal polymer layers with one atop the other from longer to shorter central wavelengths of reflecting light
  • a polarizer which includes a circular polarization-separating layer with a helical pitch changing in the thickness direction and a phase difference layer located in a long wavelength side of the central wavelength of reflecting light
  • the entire distribution of selective reflection central wavelength has been formed by stacking a plurality of layers having different selective reflection central wavelengths with one atop another or continuously changing a pitch length in a single layer.
  • methods of continuously changing a pitch length in the thickness direction are disclosed in Japanese Laid-Open Patent Application No. Hei 06-281814, Japanese Patent No. 3272668, Japanese Laid- Open Patent Application No. Hei 11-248943 and the like. These methods have technical characteristics in that, when a cholesteric liquid crystal composition is cured by exposure, synthesis rates are made different by setting different exposure strengths to an exposure side and an emission side, respectively, such that content changes in liquid compositions of different reaction rates are obtained the thickness direction.
  • the broadband circular polarization reflector also has to be combined with a phase difference plate and thus, these methods can neither prevent some problems such as complicated secondary process steps, increased process steps and light loss.
  • the present invention has been made to solve the foregoing problems with the prior art, and therefore an aspect the present invention is to provide a reflective polarizer having broadband cholesteric liquid crystal, which has a broadband reflection range to perform a circular polarization-separating function as well as a linear polarization function, and a manufacturing method thereof.
  • a reflective polarizer which may include a cholesteric liquid crystal layer having a longer wavelength pitch from bottom to top to have a visible light range as a selective reflection wavelength range; and a nematic liquid layer formed atop the cholesteric liquid crystal layer to cause a ⁇ /4 phase retardation.
  • a method of manufacturing a reflective polarizer may include procedures of: forming a nematic liquid crystal layer by applying a nematic liquid crystal material on a substrate, followed by cooling the substrate; forming a cholesteric liquid crystal layer by applying a cholesteric liquid crystal material on a substrate, followed by orientating the cholesteric liquid crystal material; stacking the nematic liquid crystal layer on the cholesteric liquid crystal layer; and diffusing the nematic liquid crystal layer into the cholesteric liquid crystal layer in the stacked liquid crystal layers such that the nematic liquid crystal layer grows to a predetermined thickness and fixing the stacked layers by curing.
  • a method of manufacturing a reflective polarizer may include procedures of: forming a nematic liquid crystal layer by applying a nematic liquid crystal material on a substrate, followed by cooling the substrate; forming a cholesteric liquid crystal layer by applying a cholesteric liquid crystal material on a substrate, followed by orientating the cholesteric liquid crystal material; stacking the nematic liquid crystal layer on the cholesteric liquid crystal layer; diffusing the nematic liquid crystal layer into the cholesteric liquid crystal layer in the stacked liquid crystal layers such that the nematic liquid crystal layer grows to a predetermined thickness and fixing the stacked layers by curing; applying a photo-curable resin on a top portion of the nematic liquid crystal layer of the cured stacked layers; and forming a prism pattern by shaping the applied photo-curable resin into prisms, followed by ultraviolet radiation and photo-curable.
  • Each of the substrates may be made of a plastic material, which is made of one selected from the group consisting of triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, amorphous polyolefin, reformed acrylic polymer and epoxy resin, or a glass plate.
  • Each of the substrates may be a releasing material.
  • the cholesteric liquid crystal material may contain a predetermined amount of chiral dopant so as to have a pitch not exceeding a wavelength of selective reflection of blue light.
  • a reflective polarizer manufactured by the method as described above and a display device including the reflective polarizer.
  • the method of manufacturing a reflective polarizer using cholesteric liquid crystal can provide a liquid crystal film having a linear polarizer function on a circular polarizer plate using a broadband cholesteric liquid crystal film by forming a nematic liquid crystal layer at a predetermined thickness on a cholesteric liquid crystal layer through controlled curing.
  • the liquid crystal film having the linear polarizer function provided as above can decrease process steps while effectively reducing light loss, which would otherwise occur due to an increasing thickness. Furthermore, it is possible to remove light loss, which would otherwise occur in a multilayer reflective polarizer film and a laminated retardation plate.
  • FIG. 1 is a schematic representation illustrating the structure of a reflective polarizer according to one embodiment of the present invention
  • FIG. 2 is a schematic representation illustrating a prism pattern of a reflective polarizer according to another embodiment of the present invention
  • FIG. 3(a-f) is a schematic representation illustrating a process of manufacturing a reflective polarizer according to an embodiment of the presentinvention
  • FIG. 4 is a schematic representation illustrating an apparatus for forming a prism pattern according to an embodiment of the present invention. Best Mode for Carrying Out the Invention
  • FIG. 1 is a schematic representation of a reflective polarizer according to one embodiment of the present invention.
  • the reflective polarizer of the present invention generally includes a cholesteric liquid crystal layer 11 and a nematic liquid crystal layer 13 formed atop the liquid crystal layer 11 to cause a ⁇ /4 phase retardation.
  • the cholesteric liquid crystal layer 11 is a mixture of a curable nematic liquid crystal material and a curable chiral material, with the selective reflection wavelength region thereof being adjustable according to the composition of the two materials.
  • any liquid crystal materials containing a mesogenic radical showing nematic liquid crystallinity are usable for the curable nematic liquid crystal material and the curable chiral material.
  • the chiral material is not limited to specific materials but can be implemented with any material containing chiral carbon in typical nematic liquid crystallinity.
  • the term "curable material” may include any materials that have thermally curable or photo-curable a reactive group in a molecular structure.
  • the curable material may be selected from a vinyl group, acrylic group, a methacrylic group or the like, or may use a combination of monomers having various reactive groups capable of condensation polymerization.
  • the curable material may use reactive groups such as a vinyl group, an acrylic group and an aryl group, which can be bridged by Ultra- Violet (UV) radiation.
  • UV Ultra- Violet
  • an initiator can also be used in the curing.
  • the cholesteric liquid crystal layer 11 has a longer wavelength pitch from bottom to top so as to have a visible wavelength range from 400nm to 800nm as a selective reflection wavelength range.
  • the selective reflection wavelength range moves to a shorter wavelength range as the content of the chiral liquid crystal material increases.
  • the content of the chiral material in the cholesteric liquid crystal layer 11 decreases from bottom to top by diffusion.
  • the reflective polarizer of the present invention also includes the nematic liquid crystal layer 13 formed atop the cholesteric liquid crystal layer 11 to cause a ⁇ /4 phase retardation.
  • the nematic liquid crystal layer 13 acts as a retardation plate to convert circular polarization, which passed through the cholesteric liquid crystal layer 11, into linear polarization.
  • the nematic liquid crystal layer 13 serves to the circular polarization, which passed through the cholesteric liquid crystal layer 11, into the linear polarization by causing a ⁇ /4 phase retardation.
  • the reflective polarizer of the present invention does not need a retardation plate unlike the prior art.
  • the present invention can effectively provide a backlight unit element including an absorptive polarizer arranged atop the reflective polarizer constructed as above, with the optical axis of the absorptive polarizer being concentric with that of the nematic liquid crystal layer 13.
  • the reflective polarizer of the present invention can be preferably formed by adding patterned prisms 15 atop the nematic liquid crystal layer 13.
  • the prism pattern 15 can improve the luminance of an LCD by effectively restrict scattering, which would otherwise occur when light passes through the liquid crystal film.
  • the prism pattern serves to refract and reflect light substantially only in a horizontal direction with respect to the plane of a light guide plate using micro- structures, which are formed with a triangular cross section on the surface of a sheet, a clear image of high luminance can be observed when viewed from a position in an angular filed of zero (0) degree.
  • transmitting light maintaining a high luminance level enters a panel by refracting and condensing at a relatively wide angle at micro- structures having a waved cross section.
  • the panel of the LCD can display an image across a wide angular field while maintaining a high luminance level.
  • the luminance and angular field can be adjusted by changing the angle of refraction of the micro- structures having a triangular cross section of the prism sheet and the angle of refraction of the micro-structures having a waved cross section of the wave- patterned sheet.
  • the angular field can be increased in a horizontal or vertical direction by changing the micro-structures (having a waved cross section) in a horizontal or vertical direction.
  • another prism pattern 17 orthogonal to the prism pattern 15 can be more preferably formed above the prism pattern 15.
  • the orthogonal prism pattern 17 added can more effectively increase the horizontal and/or vertical angular fields.
  • the prism patterns 15 and 17 of the present invention can be made of a single or mixed resin composition selected from the group consisting of acrylic resins, urethane resins, epoxy resins, vinyl resins, polyester resins and polyamide resins.
  • the resin composition can be used by adding a photo-initiator, followed by curing under UV radiation.
  • FIG. 3 is a representation illustrating the process of manufacturing a reflective polarizer according to an embodiment of the present invention.
  • a cholesteric liquid crystal material is prepared by mixing a nematic liquid crystal material and a chiral dopant material containing a small amount of asymmetric carbon group using an organic solvent and is then applied to a substrate 21.
  • the cholesteric liquid crystal material can be prepared by heating the nematic liquid crystal material and the chiral dopant material instead of using the organic solvent. In this case, a following drying procedure for removing the organic solvent will be excluded.
  • the applying procedure can be enabled using a typical coater, and examples of the organic solvent may include methylene chloride, cyclohexanone, trichloroethylene, tetrachloroethane, N-methylpyrrolidone, tetrahydrofuran, toluene, methylethylketone and the like.
  • the cholesteric liquid crystal material that contains a predetermined amount of chiral dopant so as to have a pitch not exceeding a wavelength of selective reflection of blue light.
  • a cholesteric liquid crystal layer 23 is formed on the substrate 21 by drying the applied liquid crystal layer and removing the organic solvent.
  • the top surface of the cholesteric liquid crystal layer 23, from which the organic solvent is dried out, can scraped using a wire bar, knife, a roll or the like, thereby orienting the liquid crystal.
  • the substrate 21 can be a plastic material, which is made of one selected from the group consisting of triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, amorphous polyolefin, reformed acrylic polymer and epoxy resin, or a glass plate.
  • a plastic material which is made of one selected from the group consisting of triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, amorphous polyolefin, reformed acrylic polymer and epoxy resin, or a glass plate.
  • the substrate 21 can be made of a releasing material.
  • a nematic liquid crystal material mixed into a typical organic solvent as described above is applied on another substrate 25.
  • the applying procedure can be performed using a typical coater.
  • the substrate can be a plastic material or a glass plate.
  • the plastic material can be selected preferably from the group consisting of triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, amorphous polyolefin, reformed acrylic polymer and epoxy resin.
  • the substrate 25 can be made of a releasing material, which can be removed after the following curing procedure.
  • a nematic liquid crystal layer 27 is formed on the substrate by drying the applied liquid crystal layer in a well-known method of the art, followed by cooling.
  • the liquid crystal layers 23 and 27 formed as above are stacked one atop the other, followed by curing.
  • the two layers are stacked one atop the other by for example roll lamination and are then subjected to curing at a room temperature or more to fix the orientation of liquid crystal.
  • the curing may include thermal curing and photo-curing.
  • the liquid crystal layers 23 and 37 diffuse into each other at the interface thereof such that the area of the cholesteric liquid layer 23 generally moves upwards as in FIGS. 3(d) and (e).
  • the cholesteric liquid crystal layer 23 has a longer wavelength pitch from bottom to top so as to have a visible light wavelength range as a selective reflection wavelength range.
  • the present invention requires controlling the curing conditions in such a fashion that the nematic liquid crystal layer 27 has a predetermined thickness. Specifically, chiral dopant diffuses into the nematic liquid crystal layer 27 according to a curing time, UV intensity, a curing temperature and the like, and a continuous long wavelength pitch is formed from the cholesteric liquid crystal layer 23 to the nematic liquid crystal layer 27 such that reflective polarization can be created in the entire visible light range.
  • the top portion of the nematic liquid crystal layer 27 can be completely cured before chiral dopant diffuses so as to covert circular polarization, exiting from the cholesteric liquid crystal layer 23, into linear polarization like a retardation plate.
  • the optimum process conditions can be varied according to characteristics of a variety of products and the entire thickness of the liquid crystal layers.
  • the heating temperature at the curing can be maintained in the range from 7O 0 C to 13O 0 C.
  • a prism pattern 29 may be additionally formed atop the nematic liquid crystal layer 27 after the substrate 25 is removed.
  • the substrate 25 may not be removed and the prism pattern may be formed on the substrate 25.
  • an orthogonal prism pattern may additionally formed on the prism pattern.
  • the present invention may include but not limited to a specific method to form the prism pattern.
  • the present invention may furtherinclude a procedure of forming the prism pattern by applying photo-curable resin on the top portion of the nematic liquid crystal layer prepared as above, shaping the applied photo-curable resin layer into prisms, radiating UV rays onto the prism-shaped photo-curable resin layer, and then optically drying the photo-curable resinlayer.
  • FIG. 4 is a schematic representation illustrating an apparatus for forming a prism pattern according to an embodiment of the present invention.
  • a photo-curing resin layer 130 is coated to a predetermined thickness on a liquid crystal stack 110, which has a nematic liquid crystal layer on the top portion thereof, using a coater 120.
  • the stack 110 is continuously moved by a carrier 150 such that continuous resin coating can be enabled.
  • the thickness of coating can be adjusted by vertical adjustment of the carrier 150 or the moving rate of the stack 110.
  • the photo-curable resin can be a single or mixed resin composition selected from the group consisting of acrylic resins, urethane resins, epoxy resins, vinyl resins, polyester resins and polyamide resins.
  • the resin composition can be used by adding a photo-initiator, followed by curing under UV radiation.
  • a volatile solvent usable in the following curing procedure is also added to the photo-curable resin.
  • a predetermined pattern 190 is formed on the resin layer 130.
  • UV rays 180 can be radiated onto the stack 130 from below to optically cure the formed pattern, thereby producing a desired prism pattern 190.
  • the UV rays are radiated onto the stack 130 from below in order to induce precedent evaporation of the volatile solvent out of the resin layer 130.
  • the reference numeral 195 is a shield that serves to shield the UV rays.
  • the photo-curing procedure evaporates the volatile solvent from the resin layer 130 such that the prism pattern 190 can be cured into a semi-solidified state.
  • the concentration of the volatile solvent added into the resin layer 130 can be preferably determined in consideration of the decreasing thickness. If an excessive amount of volatile solvent is contained in the resin layer 130, bubbles may grow in the curing up to a size that leaves marks on the surface of the resin layer. Accordingly, the content of the volatile solvent contained in the resin layer 130 may preferably be under 50 % by weight.
  • the present invention can effectively provide a broadband cholesteric liquid crystal layer having a broadband reflection range, which can perform a circular polarization-separating function as well as a linear polarization function, by forming a nematic liquid crystal layer having a desired thickness atop a cholesteric liquid crystal layer.
  • the reflective polarizer of the present invention includes broadband cholesteric liquid crystal, which can perform both a circular polarization- separating function and a linear polarizer function unlike the prior art. Accordingly, the present invention can remove light loss, which would otherwise occur in a multilayer reflective polarizer film and a laminated retardation plate, and be used in the manufacture of reflective polarizer plates used in LCDs due to decreased processsteps.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Health & Medical Sciences (AREA)
  • Ophthalmology & Optometry (AREA)
  • Mechanical Engineering (AREA)
  • Mathematical Physics (AREA)
  • Polarising Elements (AREA)

Abstract

La présente invention concerne un procédé permettant de fabriquer un polariseur réfléchissant contenant des cristal liquide cholestérique à large bande ainsi qu'un polariseur réfléchissant. Le procédé consiste à : former une couche de cristal liquide nématique en appliquant un matériau à cristal liquide nématique sur un substrat, et ensuite à refroidir le substrat ; former une couche de cristal liquide cholestérique en appliquant un matériau à cristal liquide cholestérique sur un substrat, et ensuite à orienter le substrat ; empiler la couche de cristal liquide nématique sur la couche de cristal liquide cholestérique ; et diffuser la couche de cristal liquide nématique à l'intérieur de la couche de cristal liquide cholestérique de l'empilement de couches, de sorte que la couche de cristal liquide nématique croît jusqu'à une épaisseur prédéterminée, ainsi qu'à fixer les couches empilées par durcissement. Selon l'invention, la couche de cristal liquide cholestérique a un plus grand espacement de longueur d'onde du bas vers le haut de manière à avoir une plage de lumière visible constituant une plage de longueur d'onde de réflexion sélective, et la couche de cristal liquide nématique provoque un retard de phase de λ/4.
PCT/KR2008/006085 2007-10-17 2008-10-15 Procédé de fabrication de polariseur réfléchissant cholestérique à lame quart d'onde, et son polariseur réfléchissant WO2009051408A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR10-2007-0104761 2007-10-17
KR1020070104761A KR100835556B1 (ko) 2007-10-17 2007-10-17 광대역 콜레스테릭 액정 반사편광자의 제조방법, 및반사편광자

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WO2009051408A1 true WO2009051408A1 (fr) 2009-04-23

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KR (1) KR100835556B1 (fr)
WO (1) WO2009051408A1 (fr)

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CN111886527A (zh) * 2018-03-23 2020-11-03 富士胶片株式会社 偏振器、偏振器的制造方法、层叠体及图像显示装置

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KR100961858B1 (ko) 2008-08-28 2010-06-09 주식회사 엘엠에스 광대역 반사편광자, 이를 갖는 백라이트 유닛 및 액정표시장치
KR100961117B1 (ko) * 2009-09-30 2010-06-07 주식회사 엘엠에스 박막형 콜레스테릭 반사편광자, 이를 갖는 백라이트 유닛 및 액정 디스플레이
KR20120031254A (ko) * 2010-08-26 2012-04-02 신화인터텍 주식회사 복합 반사 편광 필름 및 그 제조 방법

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KR19990080751A (ko) * 1998-04-21 1999-11-15 권문구 피디엘씨를 이용한 광대역특성을 갖는 편광막의 제조방법
KR20020036311A (ko) * 2000-11-09 2002-05-16 권문구 네마틱 액정을 이용한 복굴절 필름 제작방법 및 이를이용한 콜레스테릭 액정 편광막
KR20030030936A (ko) * 2001-10-10 2003-04-18 닛토덴코 가부시키가이샤 적층 위상차판, 편광 부재 및 액정 표시 장치

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KR20020036311A (ko) * 2000-11-09 2002-05-16 권문구 네마틱 액정을 이용한 복굴절 필름 제작방법 및 이를이용한 콜레스테릭 액정 편광막
KR20030030936A (ko) * 2001-10-10 2003-04-18 닛토덴코 가부시키가이샤 적층 위상차판, 편광 부재 및 액정 표시 장치

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111886527A (zh) * 2018-03-23 2020-11-03 富士胶片株式会社 偏振器、偏振器的制造方法、层叠体及图像显示装置

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