WO2010147355A2 - Reflective plate for backlight unit, backlight unit comprising the same and liquid crystal display - Google Patents

Reflective plate for backlight unit, backlight unit comprising the same and liquid crystal display Download PDF

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Publication number
WO2010147355A2
WO2010147355A2 PCT/KR2010/003826 KR2010003826W WO2010147355A2 WO 2010147355 A2 WO2010147355 A2 WO 2010147355A2 KR 2010003826 W KR2010003826 W KR 2010003826W WO 2010147355 A2 WO2010147355 A2 WO 2010147355A2
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WO
WIPO (PCT)
Prior art keywords
liquid crystal
cholesteric liquid
backlight unit
crystal layer
reflective
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PCT/KR2010/003826
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French (fr)
Korean (ko)
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WO2010147355A3 (en
Inventor
조기호
심용식
장혜진
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주식회사 엘엠에스
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Publication of WO2010147355A2 publication Critical patent/WO2010147355A2/en
Publication of WO2010147355A3 publication Critical patent/WO2010147355A3/en

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    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0055—Reflecting element, sheet or layer
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0056—Means for improving the coupling-out of light from the light guide for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/40—Properties of the layers or laminate having particular optical properties
    • B32B2307/416—Reflective
    • 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
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G02F1/133605—Direct backlight including specially adapted reflectors
    • 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
    • G02F2201/00—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00
    • G02F2201/34—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 reflector
    • G02F2201/343—Constructional arrangements not provided for in groups G02F1/00 - G02F7/00 reflector cholesteric liquid crystal reflector

Definitions

  • the present invention relates to a reflector for a backlight unit, and more particularly, to improve the reflectance of a specific region having low reflectivity among reflecting light regions reflecting incident light through the reflector to a reflectance level of another region to compensate for color differences. Furthermore, the present invention relates to a reflector for a backlight unit capable of improving color reproducibility of the entire liquid crystal display, a backlight unit having the same, and a liquid crystal display.
  • LCDs liquid crystal displays
  • the liquid crystal display displays an image by using a difference in refractive index of light according to the anisotropy of the liquid crystal injected between the array substrate and the color filter substrate, and has a structure in which polarizers are disposed on the front and rear surfaces of the two substrates.
  • the liquid crystal display cannot emit light by itself, it is dimmed by a backlight unit composed of various optical systems.
  • FIG. 1 is an exemplary view illustrating a configuration of the above-mentioned conventional liquid crystal display, which is roughly divided into a backlight unit 10 and a liquid crystal panel unit 20.
  • the backlight unit 10 includes a light source 11 for irradiating light, a light guide plate 12 for distributing light incident from the light source, an reflector 13 for reflecting light emitted from the light guide plate, and a light guide plate 12.
  • a diffuser sheet 14 for diffusing the emitted light a prism sheet 15 for condensing light incident from the diffusion sheet 14, and a polarizer 16 for transmitting light in one direction among the light emitted from the prism sheet 15.
  • a phase delay plate 17 for converting circularly polarized light emitted from the polarizer 16 into linearly polarized light.
  • the reflective plate 13 is made of a non-ferrous metal material such as silver (silver), aluminum (AL), etc. having a high reflectance in order to reflect part of the light emitted from the light guide plate 12 and re-incident to the light guide plate 12 Or a plurality of polymer layers are stacked in multiple stages.
  • a non-ferrous metal material such as silver (silver), aluminum (AL), etc. having a high reflectance in order to reflect part of the light emitted from the light guide plate 12 and re-incident to the light guide plate 12
  • a plurality of polymer layers are stacked in multiple stages.
  • the conventional reflector having such a structure shows excellent reflectance in most regions of visible light, reflectance is lowered in a specific region near the short wavelength of visible light adjacent to ultraviolet rays, resulting in reduced luminance and color difference. Furthermore, there was a problem that the color reproducibility of the entire liquid crystal display is lowered.
  • the present invention has been made to solve the above-mentioned conventional problems, the object of the present invention is to improve the reflectance of the specific region of low visible light reflectance of the incident light through the reflecting plate to the reflectance level of other areas
  • the present invention provides a reflective plate for a backlight unit that can compensate for color difference and further improve color reproducibility of the entire liquid crystal display, and a backlight unit and a liquid crystal display provided with such a reflective plate.
  • the reflection plate for the backlight unit of the present invention for achieving the above object is a reflection plate provided in the backlight unit to reflect the incident light, a reflection layer for reflecting the incident random polarized light, disposed on one surface of the reflective layer of a specific region A first cholesteric liquid crystal layer configured to reflect the first polarized light and transmit the second polarized light, and a second cholesteric made to reflect the second polarized light of a specific region transmitted through the first cholesteric liquid crystal layer A first cholesteric liquid crystal layer and a second cholesteric liquid crystal layer, wherein the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer have a wavelength range that is relatively lower than a wavelength of a region having a different reflectance by the reflective layer among arbitrary reflective regions of light to be reflected by the reflective layer; It characterized in that it has a reflected wavelength band inducing total reflection for the polarization belonging to.
  • the reflection wavelength bands of the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer are in a range of not less than the shortest wavelength and not more than 150 nm longer than the shortest wavelength among the arbitrary reflection areas of the reflective layer.
  • the arbitrary reflection region includes all visible light regions, and the reflection wavelength bands of the first and second cholesteric liquid crystal layers are the shortest wavelengths of the visible light region bordering the ultraviolet region. It can be made in the range of the wavelength above 150 nm longer than this and the shortest wavelength.
  • the first cholesteric liquid crystal layer may be implemented by stacking several cholesteric liquid crystals having different center wavelengths.
  • the second cholesteric liquid crystal layer may be implemented to stack several cholesteric liquid crystals having different center wavelengths.
  • the first cholesteric liquid crystal layer is composed of a single cholesteric liquid crystal having a pitch change continuously from the bottom to the top to reflect the first polarized light.
  • the second cholesteric liquid crystal layer may be formed of a single cholesteric liquid crystal having a pitch change continuously while going from bottom to top to reflect the second polarized light.
  • the reflective layer may be made of a reflective material coated on at least one surface of the cholesteric liquid crystal layer.
  • the reflective material is preferably made of at least one selected from gold, silver, copper, nickel, aluminum, Tio2.
  • the entire reflective region since the first and second polarization of the unreflected specific region in the reflective layer is reflected by the first and second cholesteric liquid crystal layer, the entire reflective region to be reflected By obtaining an even reflectance for the to compensate for the difference in the color, which not only improves the brightness but also has a very useful effect to improve the color reproducibility of the entire liquid crystal display.
  • 1 is an exemplary view showing a conventional liquid crystal display.
  • FIG 2 is an exemplary view showing a backlight unit according to the present invention.
  • FIG 3 is an exemplary view showing a reflecting plate according to the present invention.
  • Figure 4 is an exemplary view showing another embodiment of the cholesteric liquid crystal layer according to the present invention.
  • FIG. 6 is an exemplary view showing a liquid crystal display according to the present invention.
  • FIG. 7 is an exemplary view showing another embodiment of a light source according to the present invention.
  • the backlight unit 100 having the cholesteric reflector 130 of the present invention distributes the light incident from the light source 110 and the light incident from the light source 110 to the entire area.
  • the light guide plate 120, the reflective layer 132, the first cholesteric liquid crystal layer 134, and the second cholesteric liquid crystal layer 136 to achieve total reflection of the first and second polarizations emitted from the light guide plate 120.
  • Including a reflector 130 made of a) is a technical idea.
  • the light source 110 irradiates light to the light guide plate 120.
  • the light source 110 is implemented as a so-called edge illumination type in which the light source 110 is disposed at at least one end of the light guide plate 120.
  • the light source 110 may be implemented as a top-down method type disposed between the reflecting plate 130 and the diffusion sheet 140 of the backlight unit as shown in FIG. 7, in which the light guide plate is omitted. Can be.
  • the light source 110 is CCFL (Cold Cathode Fluorescent), EEFL (External Electrode Flourescent Lamp), EL (Electrluminescent), FFL (Flat Flourescent Lamp), LED ( Light Emitting Diodes;
  • the light guide plate 120 diffuses and scatters the light emitted from the light source 110, the light guide plate 120 is uniformly distributed over the entire area and is emitted to the liquid crystal panel unit 200 (shown in FIG. 6). It is preferably made of an acrylic resin having transparency, and at least one surface of the light guide plate 120 is preferably provided with a scattering pattern (not shown) to diffuse and scatter incident light.
  • the scattering pattern may be implemented by printing a screen with a dot on one surface of the light guide plate 120 or by providing an uneven pattern on one surface of the light guide plate 120.
  • the scattering pattern may be implemented by forming a prism pattern on one surface of the light guide plate 120 to be integrally formed on the light guide plate 120.
  • the light guide plate 120 may contain fine particles, which may be made of any one of transparent materials including acryl, styrene, silicon, synthetic silica, diamond, or the like, or may include titanium oxide, zinc oxide, and sulfuric acid. It is made of any one of white materials including barium, calcium carbonate, magnesium carbonate, aluminum hydroxide, clay and the like to diffuse and scatter incident light incident on the light guide plate 120. If necessary, the microparticles may incorporate several selected materials from the above materials into the light guide plate 120.
  • the reflective plate 130 reflects incident light, and more preferably, is disposed under the light guide plate 120 to re-inject the first polarized light and the second polarized light emitted from the light guide plate 120 into the light guide plate 120.
  • a reflecting plate includes a reflective layer 132 that reflects randomly polarized light that is incident, that is, a random polarized light emitted from the light guide plate 120, and a first polarized light of a specific region that is not reflected by the reflective layer 132.
  • the first and second cholesteric liquid crystal layers 134 and 136 reflecting the L1 and the second polarization L2 are stacked.
  • the reflective layer 132 is preferably made of a non-ferrous metal material such as silver (silver), aluminum (AL), which has excellent reflectance.
  • the reflective layer 132 may have a structure in which a plurality of polymer layers are stacked in multiple stages.
  • the reflective layer 132 may be formed of a reflective material coated on one surface of the cholesteric liquid crystal layers 134 and 136 described below.
  • the reflective material is made of at least one selected from gold, silver, copper, cupper, nickel, aluminum, aluminum, and titanium dioxide (TiO 2) having excellent reflectance.
  • the reflective layer 132 may be formed of a base material and a reflective material applied to at least one surface of the base material.
  • the first and second cholesteric liquid crystal layers 134 and 136 are implemented as cholesteric liquid crystals in which a very thin layer of each molecule forms a spiral structure as a whole.
  • the spiral rotation direction coincides with the circular polarization direction, and the wavelength reflects only circular polarized light such as spiral pitch, and the reflection wavelength band can be adjusted according to the coating thickness of the liquid crystal and the length of the spiral pitch.
  • the first cholesteric liquid crystal layer 134 and the second cholesteric liquid crystal layer 136 may be formed in a specific region having a relatively lower reflectance than a wavelength of another region among arbitrary reflection regions to be reflected by the reflective layer 132. And a reflection wavelength band which induces total reflection for the polarized light in the wavelength range.
  • the arbitrary reflection region means an area to be reflected through the reflection layer 132 without being specified among the wavelength bands.
  • the arbitrary reflection area may include all visible light areas or only some visible light areas.
  • the reflection wavelength band of the first cholesteric liquid crystal layer 134 and the second cholesteric liquid crystal layer 136 is also different.
  • the arbitrary reflection region includes a wavelength of 380 nm to 780 nm, which is a visible light region, and the reflection layer is made of silver, the first cholesteric liquid crystal layer 134 and the second cholesteric liquid crystal layer 136 are reflected.
  • the wavelength band ranges from the shortest wavelength of the visible region, which is bordered with the ultraviolet region, to a wavelength 150 nm longer than the shortest wavelength (i.e., the shortest visible region) In a range of 380 nm to 530 nm, which is greater than or equal to and less than or equal to 150 nm longer than the shortest wavelength. Also, for example, when the arbitrary reflection region includes a wavelength of 350 to 650 nm including a portion of the ultraviolet region and a portion of the visible region, the first range may be in the range of 350 nm to 500 nm.
  • the arbitrary reflection region does not refer to only one wavelength band, but depends on the selection of the region to be reflected through the reflection layer, and thus the first cholesteric liquid crystal layer 134 and the second cholesteric It is clear that the reflection wavelength band of the liquid crystal layer 136 is also varied.
  • FIG. 3 illustrates a cross-sectional view of the reflective layer 132 and the first and second cholesteric liquid crystal layers 134 and 136 stacked.
  • the second cholesteric liquid crystal layer 136 is stacked on the reflective layer 132, and the first cholesteric is deposited on the second cholesteric liquid crystal layer 136.
  • the liquid crystal layer 134 is stacked, the stacking order of the first cholesteric liquid crystal layer 134 and the second cholesteric liquid crystal layer 136 is not limited in the present invention.
  • the reflection layer 132 reflects the random polarization L3 of the visible region, while the first polarization L1 of the specific region is the first cholesteric liquid crystal layer. 134, and the second polarization L2 of the specific region is reflected by the second cholesteric liquid crystal layer 136. Therefore, the random polarized light including the first polarized light L1 and the second polarized light L2 of the specific region emitted from the light guide plate 120 includes the reflective layer 132, the first cholesteric liquid crystal layer 134, and the second cholesterol. Total reflection is induced by the liquid crystal layer 136.
  • the first and second cholesteric liquid crystal layers 134 and 136 may be implemented as a single cholesteric liquid crystal. That is, the cholesteric liquid crystal has a continuous pitch change from top to bottom to selectively reflect different polarizations.
  • FIG. 4 is a cross-sectional view showing another embodiment of the first and second cholesteric liquid crystal layers 134 and 136, and the first and second cholesteric liquid crystal layers 134 and 136 of the present invention.
  • Silver may be implemented by stacking several cholesteric liquid crystals having different center wavelengths in multiple stages. That is, several cholesteric liquid crystals having different center wavelengths are stacked in multiple stages to selectively reflect polarizations of different wavelength bands.
  • the cholesteric liquid crystal layer of any one of the first and second cholesteric liquid crystal layer 134, 136 of the present invention consists of a single cholesteric liquid crystal, the remaining cholesteric liquid crystal layer is the center Several cholesteric liquid crystals having different wavelengths may be implemented in a stacked form.
  • the backlight unit having a reflector plate made of silver is disposed under the light guide plate.
  • the reflecting plate made of the comparative example conditions has a lower reflectance in the 380 to 450 nm region compared to other visible light regions (450 to 700 nm).
  • the reflectance of the reflector made of the embodiment conditions is uniformly distributed over all visible light.
  • the reflector plated under the conditions of the embodiment compensates for the difference in color as it exhibits uniform reflectance in all visible light regions, compared to the reflector modeled under the conditions of the comparative example, and furthermore, the color reproducibility of the entire liquid crystal display. Will improve.
  • FIG. 6 is a view illustrating a liquid crystal display having a backlight unit configured as described above.
  • the liquid crystal display includes a backlight unit 100 and a liquid crystal panel unit 200.
  • the backlight unit 100 includes a diffusion sheet 140 that transforms the light incident from the light guide plate 120 into a surface light source having uniform brightness, in addition to the light source 110, the light guide plate 120, and the reflective plate 130.
  • the light emitting device may further include at least one prism sheet 150 for condensing the light emitted from the diffusion sheet 140 and outputting the light to the reflective polarization film 160.
  • the liquid crystal panel unit 200 may include a liquid crystal, a front polarizer and a rear polarizer provided on the front and rear surfaces of the liquid crystal, and an absorption type polarizer may be interposed between the rear polarizer and the reflective polarizer.
  • the present invention since the first and second polarizations of the specific region unreflected in the reflection layer are reflected by the first and second cholesteric liquid crystal layers, an even reflectance is obtained for the entire reflection region to be reflected and thus, Complement of the difference, which can improve the luminance as well as the color reproducibility of the entire liquid crystal display is a very useful technology in the technical field of the present invention.

Abstract

The present invention relates to a reflective plate for a backlight unit. The reflective plate for a backlight unit is arranged in the backlight unit to reflect incident light, and comprises: a reflective layer for reflecting incident random polarized light; a first cholesteric liquid crystal layer formed at one side of the reflective layer to reflect first polarized light in a specific area and transmit second polarized light in the specific area therethrough; and a second cholesteric liquid crystal layer arranged to reflect the second polarized light in the specific area, transmitted through the first cholesteric liquid crystal layer, wherein the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer have reflective wavelength bands for reflecting light in a specific area having a low reflectivity, from among an arbitrary reflection area to be reflected by the reflective layer. Consequently, the present invention improves reflectivity of the specific area having a low reflectivity, from among the visible light area for reflecting incident light through a reflective plate, thereby compensating a color difference.

Description

백라이트 유닛용 반사판, 이를 갖는 백라이트 유닛 및 액정 디스플레이Reflector for backlight unit, backlight unit and liquid crystal display having same
본 발명은 백라이트 유닛용 반사판 등에 관한 것으로서, 더욱 상세하게는 반사판을 통해 입사광을 반사시키는 가시광선 영역 중, 반사율이 낮은 특정영역의 반사율을 다른 영역의 반사율 수준으로 향상시켜서 색상의 차이를 보완하며, 더 나아가서는 액정 디스플레이 전체의 색 재현성을 향상시킬 수 있는 백라이트 유닛용 반사판, 이를 갖는 백라이트 유닛 및 액정 디스플레이에 관한 것이다.The present invention relates to a reflector for a backlight unit, and more particularly, to improve the reflectance of a specific region having low reflectivity among reflecting light regions reflecting incident light through the reflector to a reflectance level of another region to compensate for color differences. Furthermore, the present invention relates to a reflector for a backlight unit capable of improving color reproducibility of the entire liquid crystal display, a backlight unit having the same, and a liquid crystal display.
주지된 바와 같이, 액정 디스플레이(Liquide Crystal Display; LCD)는 노트북이나 퍼스널 컴퓨터 또는 TV 등의 정보용 디스플레이로서 널리 사용되고 있다.As is well known, liquid crystal displays (LCDs) are widely used as information displays for notebooks, personal computers or TVs.
이러한 액정 디스플레이는 어레이 기판과 컬러필터 기판 사이에 주입된 액정의 이방성에 따른 빛의 굴절률 차이를 이용하여 영상을 표시하며, 상기 두 기판의 전면 및 후면에는 편광막이 배치되는 구조로 이루어진다. 그리고 액정디스플레이는 스스로 빛을 낼 수 없기 때문에 다양한 광학계로 구성된 백라이트 유닛에 의해 조광된다.The liquid crystal display displays an image by using a difference in refractive index of light according to the anisotropy of the liquid crystal injected between the array substrate and the color filter substrate, and has a structure in which polarizers are disposed on the front and rear surfaces of the two substrates. In addition, since the liquid crystal display cannot emit light by itself, it is dimmed by a backlight unit composed of various optical systems.
첨부된 도 1은 위에서 언급한 종래의 액정 디스플레이의 구성을 도시한 예시도로서, 백라이트 유닛(10)과 액정패널 유닛(20)으로 대별된다.1 is an exemplary view illustrating a configuration of the above-mentioned conventional liquid crystal display, which is roughly divided into a backlight unit 10 and a liquid crystal panel unit 20.
그리고 백라이트 유닛(10)은 광을 조사하는 광원(11), 광원으로부터 입사된 광을 전체 면적으로 분포시키는 도광판(12), 도광판에서 방출된 광을 반사시키는 반사판(13), 도광판(12)에서 출사된 광을 확산시키는 확산시트(14), 확산시트(14)로부터 입사된 광을 집광시키는 프리즘시트(15), 프리즘시트(15)에서 출사된 광 중 일방향의 광을 투과시키는 편광자(16), 편광자(16)에서 출사된 원편광을 선편광으로 전환시키는 위상지연판(17)으로 구성된다.The backlight unit 10 includes a light source 11 for irradiating light, a light guide plate 12 for distributing light incident from the light source, an reflector 13 for reflecting light emitted from the light guide plate, and a light guide plate 12. A diffuser sheet 14 for diffusing the emitted light, a prism sheet 15 for condensing light incident from the diffusion sheet 14, and a polarizer 16 for transmitting light in one direction among the light emitted from the prism sheet 15. And a phase delay plate 17 for converting circularly polarized light emitted from the polarizer 16 into linearly polarized light.
여기서, 상기 반사판(13)은 도광판(12)에서 방출된 광의 일부를 반사하여 도광판(12)으로 재입사시키기 위해, 반사율이 우수한 은(Silver), 알루미늄(Aluminium, AL) 등의 비철금속 재질로 이루어지거나, 다수개의 고분자층이 다단으로 적층되는 구조로 이루어진다.Here, the reflective plate 13 is made of a non-ferrous metal material such as silver (silver), aluminum (AL), etc. having a high reflectance in order to reflect part of the light emitted from the light guide plate 12 and re-incident to the light guide plate 12 Or a plurality of polymer layers are stacked in multiple stages.
그러나, 이와 같이 구성된 종래의 반사판은 가시광선 대부분의 영역에서 우수한 반사율을 나타내기는 하지만, 자외선에 인접된 가시광선의 단파장 부근의 특정영역에서는 반사율이 저하되어 휘도가 감소하고 색상의 차이가 발생되며, 더 나아가서는 액정 디스플레이 전체의 색 재현성이 낮아지게 되는 문제점이 있었다.However, although the conventional reflector having such a structure shows excellent reflectance in most regions of visible light, reflectance is lowered in a specific region near the short wavelength of visible light adjacent to ultraviolet rays, resulting in reduced luminance and color difference. Furthermore, there was a problem that the color reproducibility of the entire liquid crystal display is lowered.
본 발명은 상기와 같은 종래의 문제점을 해결하기 위해 안출한 것으로서, 본 발명의 목적은 반사판을 통해 입사광을 반사시키는 가시광선 영역 중, 반사율이 낮은 특정영역의 반사율을 다른 영역의 반사율 수준으로 향상시켜서 색상의 차이를 보완하며, 더 나아가서는 액정 디스플레이 전체의 색 재현성을 향상시킬 수 있는 백라이트 유닛용 반사판과, 이러한 반사판이 구비된 백라이트 유닛 및 액정 디스플레이를 제공하는 데 있다.The present invention has been made to solve the above-mentioned conventional problems, the object of the present invention is to improve the reflectance of the specific region of low visible light reflectance of the incident light through the reflecting plate to the reflectance level of other areas The present invention provides a reflective plate for a backlight unit that can compensate for color difference and further improve color reproducibility of the entire liquid crystal display, and a backlight unit and a liquid crystal display provided with such a reflective plate.
상기 목적을 달성하기 위한 본 발명의 백라이트 유닛용 반사판은, 입사되는 광을 반사시키도록 백라이트 유닛에 구비된 반사판에 있어서, 입사되는 랜덤편광을 반사시키는 반사층, 상기 반사층의 일면에 배치되어 특정영역의 제1편광을 반사시 키고 제2편광은 투과시키도록 이루어진 제1콜레스테릭 액정층, 상기 제1콜레스테릭 액정층을 투과한 특정영역의 제2편광을 반사시키도록 이루어진 제2콜레스테릭 액정층을 포함하며, 상기 제1콜레스테릭 액정층과 제2콜레스테릭 액정층은 상기 반사층에서 반사시키고자 하는 광의 임의 반사영역 중에서 반사층에 의한 반사율이 다른 영역의 파장보다 상대적으로 낮은 파장 범위에 속하는 편광에 대한 전반사를 유도하는 반사파장대역을 갖는 것을 특징으로 한다.The reflection plate for the backlight unit of the present invention for achieving the above object is a reflection plate provided in the backlight unit to reflect the incident light, a reflection layer for reflecting the incident random polarized light, disposed on one surface of the reflective layer of a specific region A first cholesteric liquid crystal layer configured to reflect the first polarized light and transmit the second polarized light, and a second cholesteric made to reflect the second polarized light of a specific region transmitted through the first cholesteric liquid crystal layer A first cholesteric liquid crystal layer and a second cholesteric liquid crystal layer, wherein the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer have a wavelength range that is relatively lower than a wavelength of a region having a different reflectance by the reflective layer among arbitrary reflective regions of light to be reflected by the reflective layer; It characterized in that it has a reflected wavelength band inducing total reflection for the polarization belonging to.
여기서, 상기 제1콜레스테릭 액정층과 제2콜레스테릭 액정층의 반사파장대역은 상기 반사층의 임의 반사영역중 최단의 파장 이상 및 이 최단의 파장보다 150nm 긴 파장 이하의 범위로 이루어진다.Here, the reflection wavelength bands of the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer are in a range of not less than the shortest wavelength and not more than 150 nm longer than the shortest wavelength among the arbitrary reflection areas of the reflective layer.
선택적으로, 상기 임의 반사영역은 모든 가시광선 영역을 포함하며, 상기 제 1콜레스테릭 액정층과 제2콜레스테릭 액정층의 반사파장대역은 자외선 영역과 경계를 이루는 가시광선 영역의 최단의 파장 이상 및 이 최단의 파장보다 150nm 긴 파장 이하의 범위로 이루어질 수 있다.Optionally, the arbitrary reflection region includes all visible light regions, and the reflection wavelength bands of the first and second cholesteric liquid crystal layers are the shortest wavelengths of the visible light region bordering the ultraviolet region. It can be made in the range of the wavelength above 150 nm longer than this and the shortest wavelength.
본 발명의 백라이트 유닛용 반사판의 실시예에 따르면, 상기 제1콜레스테릭 액정층은 중심파장이 상이한 수개의 콜레스테릭 액정이 적층되는 것으로 구현될 수 있다. 이때, 상기 제2콜레스테릭 액정층은 중심파장이 상이한 수개의 콜레스테릭 액정이 적층되는 것을 구현될 수 있다.According to an embodiment of the reflector for backlight unit of the present invention, the first cholesteric liquid crystal layer may be implemented by stacking several cholesteric liquid crystals having different center wavelengths. In this case, the second cholesteric liquid crystal layer may be implemented to stack several cholesteric liquid crystals having different center wavelengths.
본 발명의 백라이트 유닛용 반사판의 다른 실시예에 따르면, 상기 제1콜레스테릭 액정층은 제1편광을 반사시키도록 하부에서 상부로 가면서 연속적으로 피치의 변화를 갖는 단일의 콜레스테릭 액정으로 이루어질 수 있다. 이때, 상기 제2콜레스테릭 액정층은 제2편광을 반사시키도록 하부에서 상부로 가면서 연속적으로 피치의 변화를 갖는 단일의 콜레스테릭 액정으로 이루어질 수 있다.According to another embodiment of the reflector for a backlight unit of the present invention, the first cholesteric liquid crystal layer is composed of a single cholesteric liquid crystal having a pitch change continuously from the bottom to the top to reflect the first polarized light. Can be. In this case, the second cholesteric liquid crystal layer may be formed of a single cholesteric liquid crystal having a pitch change continuously while going from bottom to top to reflect the second polarized light.
한편, 본 발명의 백라이트 유닛용 반사판의 또 다른 실시예에 따르면, 상기 반사층은 콜레스테릭 액정층의 적어도 어느 일면으로 코팅된 반사물질로 이루어질 수 있다. 이때, 상기 반사물질은 금, 은, 구리, 니켈, 알루미늄, Tio2 중 선택된 적어도 어느 하나로 이루어지는 것이 바람직하다.On the other hand, according to another embodiment of the reflective plate for the backlight unit of the present invention, the reflective layer may be made of a reflective material coated on at least one surface of the cholesteric liquid crystal layer. In this case, the reflective material is preferably made of at least one selected from gold, silver, copper, nickel, aluminum, Tio2.
이를 통해 상술한 바와 같은 백라이트 유닛을 갖는 액정디스플레이가 구현된다.As a result, a liquid crystal display having the backlight unit as described above is implemented.
상기와 같은 수단으로 구현된 본 발명에 따르면, 반사층에서 미반사된 특정영역의 제1편광 및 제2편광이 제1 및 제2콜레스테릭 액정층에 의해 반사되므로, 반사시키고자하는 반사영역 전체에 대해 고른 반사율을 얻게 되어 색상의 차이를 보완하게 되며, 이로 인해 휘도 또한 향상될 뿐만 아니라 액정 디스플레이 전체의 색 재현성을 향상시킬 수 있는 매우 유용한 효과가 있다.According to the present invention implemented by the above means, since the first and second polarization of the unreflected specific region in the reflective layer is reflected by the first and second cholesteric liquid crystal layer, the entire reflective region to be reflected By obtaining an even reflectance for the to compensate for the difference in the color, which not only improves the brightness but also has a very useful effect to improve the color reproducibility of the entire liquid crystal display.
도 1은 종래의 액정 디스플레이를 도시한 예시도.1 is an exemplary view showing a conventional liquid crystal display.
도 2는 본 발명에 의한 백라이트 유닛을 도시한 예시도.2 is an exemplary view showing a backlight unit according to the present invention.
도 3은 본 발명에 의한 반사판을 도시한 예시도.3 is an exemplary view showing a reflecting plate according to the present invention.
도 4는 본 발명에 의한 콜레스테릭 액정층의 다른 실시예를 도시한 예시도.Figure 4 is an exemplary view showing another embodiment of the cholesteric liquid crystal layer according to the present invention.
도 5는 본 발명에 의한 실시예 및 비교예의 결과를 도시한 그래프.5 is a graph showing the results of Examples and Comparative Examples according to the present invention.
도 6은 본 발명에 의한 액정 디스플레이를 도시한 예시도.6 is an exemplary view showing a liquid crystal display according to the present invention.
도 7은 본 발명에 의한 광원의 다른 실시예를 도시한 예시도.7 is an exemplary view showing another embodiment of a light source according to the present invention.
이하에서는 본 발명의 바람직한 실시예를 첨부된 도면을 참조하여 상세히 설명한다.Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail.
본 발명의 콜레스테릭 반사판(130)이 구비된 백라이트 유닛(100)은 도 2에 도시된 바와 같이, 광을 조사하는 광원(110), 광원(110)으로부터 입사된 광을 전체 면적으로 분포시키는 도광판(120), 도광판(120)에서 방출된 제1편광 및 제2편광에 대한 전반사를 도모하도록 반사층(132)와 제1콜레스테릭 액정층(134) 및 제2콜레스테릭 액정층(136)으로 이루어진 반사판(130)을 포함하는 것을 기술적인 사상으로 한다.As shown in FIG. 2, the backlight unit 100 having the cholesteric reflector 130 of the present invention distributes the light incident from the light source 110 and the light incident from the light source 110 to the entire area. The light guide plate 120, the reflective layer 132, the first cholesteric liquid crystal layer 134, and the second cholesteric liquid crystal layer 136 to achieve total reflection of the first and second polarizations emitted from the light guide plate 120. Including a reflector 130 made of a) is a technical idea.
광원(110)은 도광판(120)으로 광을 조사하는 것으로서, 도 2에서는 도광판(120)의 적어도 어느 한 단부에 광원(110)이 배치된 이른바 엣지형(Edge illumination type)으로 구현되었으나, 필요에 따라 광원(110)은 도 7에 도시된 바와 같이, 백라이트 유닛의 반사판(130)과 확산시트(140) 사이에 배치된 직하형(Top-Down method type)으로 구현될 수 있으며, 이때 도광판은 생략될 수 있다. 그리고 광원(110)은 CCFL(Cold Cathode Fluorescent; 냉음극 형광램프), EEFL(External Electrode Flourescent Lamp; 외부전극 형광램프), EL(Electrluminescent), FFL(Flat Flourescent Lamp; 평판형 형광램프), LED(Light Emitting Diodes; 발광다이오드) 중 선택된 어느 하나로 구현된다.The light source 110 irradiates light to the light guide plate 120. In FIG. 2, the light source 110 is implemented as a so-called edge illumination type in which the light source 110 is disposed at at least one end of the light guide plate 120. Accordingly, the light source 110 may be implemented as a top-down method type disposed between the reflecting plate 130 and the diffusion sheet 140 of the backlight unit as shown in FIG. 7, in which the light guide plate is omitted. Can be. And the light source 110 is CCFL (Cold Cathode Fluorescent), EEFL (External Electrode Flourescent Lamp), EL (Electrluminescent), FFL (Flat Flourescent Lamp), LED ( Light Emitting Diodes;
도광판(120)은 광원(110)에서 조사된 광을 확산 및 산란시킴에 따라 전체 면적으로 균일하게 분포시켜서 액정패널 유닛(200; 도 6에 도시)으로 출사시키는 것으로서, 이러한 도광판(120)은 광투과성을 갖는 아크릴수지로 이루어지며, 도광판(120)의 적어도 어느 일면에는 입사광을 확산 및 산란시키도록 산란패턴(도시 생략)이 구비되는 것이 바람직하다.As the light guide plate 120 diffuses and scatters the light emitted from the light source 110, the light guide plate 120 is uniformly distributed over the entire area and is emitted to the liquid crystal panel unit 200 (shown in FIG. 6). It is preferably made of an acrylic resin having transparency, and at least one surface of the light guide plate 120 is preferably provided with a scattering pattern (not shown) to diffuse and scatter incident light.
상기 산란패턴은 도광판(120)의 일면에 도트(dot)가 구비된 스크린을 인쇄하거나, 도광판(120)의 일면에 요철패턴을 구비하는 방식으로 구현될 수 있다. 또는 상기 산란패턴은 도광판(120)의 일면에 프리즘패턴을 성형하여 도광판(120)에 일체로 형성하는 방식으로 구현될 수 있다.The scattering pattern may be implemented by printing a screen with a dot on one surface of the light guide plate 120 or by providing an uneven pattern on one surface of the light guide plate 120. Alternatively, the scattering pattern may be implemented by forming a prism pattern on one surface of the light guide plate 120 to be integrally formed on the light guide plate 120.
선택적으로, 상기 도광판(120)에는 미세입자가 함유될 수 있는데, 이러한 미세입자는 아크릴, 스티렌, 실리콘, 합성실리카, 다이아몬드 등을 포함하는 투명한 재료 중 어느 하나로 이루어지거나, 산화티탄, 산화아연, 황산바륨, 탄산칼슘, 탄산마그네슘, 수산화알루미늄, 클레이 등을 포함하는 백색 재료 중 어느 하나로 이루어져, 도광판(120)으로 입사된 입사광을 확산 및 산란시키게 된다. 필요에 따라, 미세입자는 상술한 재료 중 선택된 수 개의 재료를 도광판(120) 내부에 혼입할 수 있다.Optionally, the light guide plate 120 may contain fine particles, which may be made of any one of transparent materials including acryl, styrene, silicon, synthetic silica, diamond, or the like, or may include titanium oxide, zinc oxide, and sulfuric acid. It is made of any one of white materials including barium, calcium carbonate, magnesium carbonate, aluminum hydroxide, clay and the like to diffuse and scatter incident light incident on the light guide plate 120. If necessary, the microparticles may incorporate several selected materials from the above materials into the light guide plate 120.
반사판(130)은 입사되는 광을 반사시키는 것으로서, 더욱 바람직하게는 도광판(120)의 하부에 배치되어 도광판(120)에서 방출된 제1편광 및 제2편광을 도광판(120)으로 재입사시키게 된다. 이러한 반사판은 입사되는 랜덤편광, 즉 도 3에 도시된 바와 같이, 도광판(120)에서 방출된 랜덤편광을 반사시키는 반사층(132)과, 이 반사층(132)에서 미반사되는 특정영역의 제1편광(L1) 및 제2편광(L2)을 반사시키는 제1 및 제2콜레스테릭 액정층(134)(136)이 적층되는 것으로 구현된다.The reflective plate 130 reflects incident light, and more preferably, is disposed under the light guide plate 120 to re-inject the first polarized light and the second polarized light emitted from the light guide plate 120 into the light guide plate 120. . Such a reflecting plate includes a reflective layer 132 that reflects randomly polarized light that is incident, that is, a random polarized light emitted from the light guide plate 120, and a first polarized light of a specific region that is not reflected by the reflective layer 132. The first and second cholesteric liquid crystal layers 134 and 136 reflecting the L1 and the second polarization L2 are stacked.
반사층(132)은 반사율이 우수한 은(Silver), 알루미늄(Aluminium, AL) 등의 비철금속 재질로 이루어지는 것이 바람직하다. 선택적으로, 반사층(132)은 다수개의 고분자층이 다단으로 적층되는 구조로 이루어질 수 있다. 선택적으로, 반사층(132)은 후술하는 어느 한 콜레스테릭 액정층(134)(136)의 일면으로 코팅되는 반사물질로 구현될 수 있다. 이때 상기 반사물질은 반사율이 우수한 금(gold), 은(Silver), 구리(cupper), 니켈(nickel), 알루미늄(Aluminium, AL), TiO2(Titanium Dioxide) 중 선택된 적어도 어느 하나 이상으로 이루어진다. 선택적으로, 상기 반사층(132)은 베이스기재와, 상기 베이스기재의 적어도 일면으로 도포되는 반사물질로 구성될 수 있다.The reflective layer 132 is preferably made of a non-ferrous metal material such as silver (silver), aluminum (AL), which has excellent reflectance. Optionally, the reflective layer 132 may have a structure in which a plurality of polymer layers are stacked in multiple stages. Optionally, the reflective layer 132 may be formed of a reflective material coated on one surface of the cholesteric liquid crystal layers 134 and 136 described below. In this case, the reflective material is made of at least one selected from gold, silver, copper, cupper, nickel, aluminum, aluminum, and titanium dioxide (TiO 2) having excellent reflectance. Optionally, the reflective layer 132 may be formed of a base material and a reflective material applied to at least one surface of the base material.
제1 및 제2콜레스테릭 액정층(134)(136)은 매우 얇은 각 분자층이 전체적으로 나선형의 구조를 이루는 콜레스테릭 액정(cholesteric liquid crystal)으로 구현되는데, 이러한 콜레스테릭 액정은 액정의 나선 회전 방향과 원편광 방향이 일치하고 파장이 나선 피치와 같은 원편광만을 반사하는 특성이 있으며, 액정의 코팅두께와 나선 피치의 길이에 따라 반사파장대역의 조절이 가능하게 된다.The first and second cholesteric liquid crystal layers 134 and 136 are implemented as cholesteric liquid crystals in which a very thin layer of each molecule forms a spiral structure as a whole. The spiral rotation direction coincides with the circular polarization direction, and the wavelength reflects only circular polarized light such as spiral pitch, and the reflection wavelength band can be adjusted according to the coating thickness of the liquid crystal and the length of the spiral pitch.
상기 제1콜레스테릭 액정층(134)과 제2콜레스테릭 액정층(136)은 상기 반사층(132)에서 반사시키고자하는 임의 반사영역 중에서 다른 영역의 파장보다 상대적으로 반사율이 낮은 특정 영역의 파장 범위에 있는 편광에 대한 전반사를 유도하는 반사파장대역을 구비한다.The first cholesteric liquid crystal layer 134 and the second cholesteric liquid crystal layer 136 may be formed in a specific region having a relatively lower reflectance than a wavelength of another region among arbitrary reflection regions to be reflected by the reflective layer 132. And a reflection wavelength band which induces total reflection for the polarized light in the wavelength range.
여기서, 상기 임의 반사영역은 파장대역 중 특정되지 않고 반사층(132)를 통해 반사시키고자하는 영역을 의미한다. 예컨대, 임의 반사영역은 가시광선 모든 영역을 포함하거나, 일부의 가시광선 영역만을 포함할 수 있다. 이러한 임의 반사영역에 따라 제1콜레스테릭 액정층(134)과 제2콜레스테릭 액정층(136)의 반사파장대역 또한 다르게 된다. 예컨대, 임의 반사영역이 가시광선 영역인 380~780nm의 파장을 포함하고 반사층이 은 재질로 이루어질 경우, 상기 제1콜레스테릭 액정층(134)과 제2콜레스테릭 액정층(136)의 반사파장대역은 반사층의 반사율이 낮은 단파장쪽의 특정영역의 편광, 즉 자외선 영역과 경계를 이루는 가시광선 영역중 최단의 파장에서부터 이 최단의 파장보다 150nm 긴 파장까지의 범위(즉, 가시광선 영역 중 최단의 파장 이상 및 이 최단의 파장보다 150nm 긴 파장 이하의 범위)인 380nm 내지 530nm의 범위로 이루어질 수 있다. 또한, 예를 들어 임의 반사영역이 자외선 영역 일부와 가시광선 영역 일부를 포함하는 350~650nm의 파장을 포함할 경우, 제1범위는 350nm 내지 500nm의 범위로 이루어질 수 있다.Here, the arbitrary reflection region means an area to be reflected through the reflection layer 132 without being specified among the wavelength bands. For example, the arbitrary reflection area may include all visible light areas or only some visible light areas. Depending on the arbitrary reflection region, the reflection wavelength band of the first cholesteric liquid crystal layer 134 and the second cholesteric liquid crystal layer 136 is also different. For example, when the arbitrary reflection region includes a wavelength of 380 nm to 780 nm, which is a visible light region, and the reflection layer is made of silver, the first cholesteric liquid crystal layer 134 and the second cholesteric liquid crystal layer 136 are reflected. The wavelength band ranges from the shortest wavelength of the visible region, which is bordered with the ultraviolet region, to a wavelength 150 nm longer than the shortest wavelength (i.e., the shortest visible region) In a range of 380 nm to 530 nm, which is greater than or equal to and less than or equal to 150 nm longer than the shortest wavelength. Also, for example, when the arbitrary reflection region includes a wavelength of 350 to 650 nm including a portion of the ultraviolet region and a portion of the visible region, the first range may be in the range of 350 nm to 500 nm.
따라서, 상기 임의 반사영역은 어느 한 파장대역만을 지칭하지 않고, 반사층을를 통해 반사시키고자하는 영역의 선택에 따라 달라지며, 이로 인해 상기 제1콜레스테릭 액정층(134)과 제2콜레스테릭 액정층(136)의 반사파장대역 또한 다르게 가변됨을 분명히 밝혀 둔다.Therefore, the arbitrary reflection region does not refer to only one wavelength band, but depends on the selection of the region to be reflected through the reflection layer, and thus the first cholesteric liquid crystal layer 134 and the second cholesteric It is clear that the reflection wavelength band of the liquid crystal layer 136 is also varied.
도 3에는 상술한 반사층(132)와 제1 및 제2콜레스테릭 액정층(134)(136)이 적층된 상태의 단면도가 도시되어 있다. 도 3에 도시된 반사판(130)은 반사층(132)의 상부에 제2콜레스테릭 액정층(136)을 적층하고, 이 제2콜레스테릭 액정층(136)의 상부에 제1콜레스테릭 액정층(134)을 적층하였으나, 본 발명에서는 제1콜레스테릭 액정층(134) 및 제2콜레스테릭 액정층(136)의 적층순서는 제한하지 않는다.3 illustrates a cross-sectional view of the reflective layer 132 and the first and second cholesteric liquid crystal layers 134 and 136 stacked. 3, the second cholesteric liquid crystal layer 136 is stacked on the reflective layer 132, and the first cholesteric is deposited on the second cholesteric liquid crystal layer 136. Although the liquid crystal layer 134 is stacked, the stacking order of the first cholesteric liquid crystal layer 134 and the second cholesteric liquid crystal layer 136 is not limited in the present invention.
도 3을 참조하여 반사판의 작용을 좀 더 살펴보면, 반사층(132)는 가시광선 대부분 영역의 랜덤편광(L3)을 반사하지만, 특정영역의 제1편광(L1)은 제1콜레스테릭 액정층(134)에 의해 반사되고, 특정영역의 제2편광(L2)은 제2콜레스테릭 액정층(136)에 의해 반사된다. 따라서 도광판(120)에서 방출된 특정영역의 제1편광(L1) 및 제2편광(L2)을 포함하는 랜덤편광은 반사층(132)와 제1콜레스테릭 액정층(134) 및 제2콜레스테릭 액정층(136)에 의해 전반사가 유도되는 것이다.Referring to FIG. 3, the reflection layer 132 reflects the random polarization L3 of the visible region, while the first polarization L1 of the specific region is the first cholesteric liquid crystal layer. 134, and the second polarization L2 of the specific region is reflected by the second cholesteric liquid crystal layer 136. Therefore, the random polarized light including the first polarized light L1 and the second polarized light L2 of the specific region emitted from the light guide plate 120 includes the reflective layer 132, the first cholesteric liquid crystal layer 134, and the second cholesterol. Total reflection is induced by the liquid crystal layer 136.
여기서, 제1 및 제2콜레스테릭 액정층(134)(136)은 단일의 콜레스테릭 액정으로 구현될 수 있다. 즉, 서로 다른 편광을 선택적으로 반사시키도록 상부에서 하부로 갈수록 연속적인 피치의 변화를 갖는 콜레스테릭 액정으로 구현되는 것이다.Here, the first and second cholesteric liquid crystal layers 134 and 136 may be implemented as a single cholesteric liquid crystal. That is, the cholesteric liquid crystal has a continuous pitch change from top to bottom to selectively reflect different polarizations.
한편, 도 4는 제1 및 제2 콜레스테릭 액정층(134)(136)의 다른 실시예를 도시한 단면도로서, 본 발명의 제1 및 제2콜레스테릭 액정층(134)(136)은 중심파장이 상이한 수개의 콜레스테릭 액정을 다단으로 적층하는 것으로 구현될 수 있다. 즉, 서로 다른 파장대역의 편광을 선택적으로 반사시키도록 중심파장이 상이한 수개의 콜레스테릭 액정이 다단으로 적층되는 것이다.4 is a cross-sectional view showing another embodiment of the first and second cholesteric liquid crystal layers 134 and 136, and the first and second cholesteric liquid crystal layers 134 and 136 of the present invention. Silver may be implemented by stacking several cholesteric liquid crystals having different center wavelengths in multiple stages. That is, several cholesteric liquid crystals having different center wavelengths are stacked in multiple stages to selectively reflect polarizations of different wavelength bands.
다른 한편, 본 발명의 제1 및 제2콜레스테릭 액정층(134)(136) 중 어느 하나의 콜레스테릭 액정층은 단일의 콜레스테릭 액정으로 이루어지고, 나머지 콜레스테릭 액정층은 중심파장이 상이한 수개의 콜레스테릭 액정이 다단으로 적층되는 형태로 구현될 수 있다.On the other hand, the cholesteric liquid crystal layer of any one of the first and second cholesteric liquid crystal layer 134, 136 of the present invention consists of a single cholesteric liquid crystal, the remaining cholesteric liquid crystal layer is the center Several cholesteric liquid crystals having different wavelengths may be implemented in a stacked form.
상술한 내용을 토대로 본 발명의 반사판과 종래의 반사판에 대한 반사율의 차이를 실험예를 통해 살펴보면 다음과 같다.Looking at the difference between the reflectivity of the reflector of the present invention and the conventional reflector based on the above description through the experimental example as follows.
<실시예><Example>
은 재질로 이루어진 반사층의 상부에, 380~450nm의 파장의 제1편광 및 제2편광을 반사시키는 제1 및 제2콜레스테릭 액정층을 적층한 반사판을 도광판의 하부에 배치하는 백라이트 유닛을 모델링하였다.Modeling a backlight unit on the lower part of the light guide plate, a reflector plate on which the first and second cholesteric liquid crystal layers reflecting the first and second polarized light having a wavelength of 380 to 450 nm is reflected on the lower part of the light guide plate. It was.
<비교예>Comparative Example
은 재질로 이루어진 반사판을 도광판의 하부에 배치하는 백라이트 유닛을 모델링하였다.The backlight unit having a reflector plate made of silver is disposed under the light guide plate.
<실험예>Experimental Example
실시예 및 비교예의 조건으로 모델링된 백라이트 유닛의 시뮬레이션을 통해 측정된 반사율을 도 5에서 그래프로 나타내었다.Reflectances measured through simulation of the backlight unit modeled under the conditions of Examples and Comparative Examples are shown in a graph in FIG. 5.
도 5의 그래프로부터, 비교예 조건으로 이루어진 반사판은 380~450nm 영역에서의 반사율이, 다른 가시광선 영역(450~700nm)에 비해 낮게 나타남을 알 수 있다.From the graph of FIG. 5, it can be seen that the reflecting plate made of the comparative example conditions has a lower reflectance in the 380 to 450 nm region compared to other visible light regions (450 to 700 nm).
반면에, 실시예 조건으로 이루어진 반사판의 반사율은 가시광선 모든 영역에 걸쳐서 균일하게 나타남을 알 수 있다.On the other hand, it can be seen that the reflectance of the reflector made of the embodiment conditions is uniformly distributed over all visible light.
결과적으로, 실시예의 조건으로 모델링된 반사판은 비교예의 조건으로 모델링된 반사판에 비해, 모든 가시광선 영역에서 균일한 반사율을 나타냄에 따라 색상의 차이를 보완하게 되며, 더 나아가서는 액정 디스플레이 전체의 색 재현성을 향상시키게 된다.As a result, the reflector plated under the conditions of the embodiment compensates for the difference in color as it exhibits uniform reflectance in all visible light regions, compared to the reflector modeled under the conditions of the comparative example, and furthermore, the color reproducibility of the entire liquid crystal display. Will improve.
한편, 첨부된 도 6은 상기와 같이 구성된 백라이트 유닛을 갖는 액정 디스플레이를 도시한 예시도로서, 이러한 액정 디스플레이는 백라이트 유닛(100)과 액정패널 유닛(200)으로 구성된다.Meanwhile, FIG. 6 is a view illustrating a liquid crystal display having a backlight unit configured as described above. The liquid crystal display includes a backlight unit 100 and a liquid crystal panel unit 200.
여기서, 백라이트 유닛(100)은 상술한 광원(110), 도광판(120), 반사판(130) 외에, 도광판(120)으로부터 입사된 광을 균일한 밝기의 면광원으로 변형시키는 확산시트(140)와, 이 확산시트(140)에서 출사된 광을 집광시켜서 반사편광필름(160)으로 출사시키는 적어도 하나의 프리즘시트(150)를 더 포함할 수 있다.Here, the backlight unit 100 includes a diffusion sheet 140 that transforms the light incident from the light guide plate 120 into a surface light source having uniform brightness, in addition to the light source 110, the light guide plate 120, and the reflective plate 130. The light emitting device may further include at least one prism sheet 150 for condensing the light emitted from the diffusion sheet 140 and outputting the light to the reflective polarization film 160.
그리고 액정패널 유닛(200)은 액정과, 이 액정의 전면 및 후면에 구비된 전면 편광막 및 후면 편광막을 포함하며, 후면편광막과 반사편광자 사이에는 흡수형 편광막이 개재될 수 있다.The liquid crystal panel unit 200 may include a liquid crystal, a front polarizer and a rear polarizer provided on the front and rear surfaces of the liquid crystal, and an absorption type polarizer may be interposed between the rear polarizer and the reflective polarizer.
본 발명은 상술한 실시예에만 한정되는 것이 아니라, 본 발명의 요지를 벗어나지 않는 범위 내에서 다양한 형태로 개량, 변경, 대체, 부가할 수 있음은 당해 기술분야에서 통상의 지식을 가진 자라면 용이하게 이해할 수 있을 것이다. 이러한 개량, 변경, 대체, 부가에 의한 실시가 이하의 특허청구범위의 범주에 속하는 것이라면 그 기술사상 역시 본 발명에 속하는 것임은 자명하다.The present invention is not limited only to the above-described embodiments, and various modifications, changes, substitutions, and additions can be made in various forms without departing from the spirit of the present invention. I can understand. If such improvement, change, replacement, or addition is carried out within the scope of the following claims, it is obvious that the technical idea also belongs to the present invention.
본 발명은 반사층에서 미반사된 특정영역의 제1편광 및 제2편광이 제1 및 제2콜레스테릭 액정층에 의해 반사되므로, 반사시키고자하는 반사영역 전체에 대해 고른 반사율을 얻게 되어 색상의 차이를 보완하게 되며, 이로 인해 휘도 또한 향상될 뿐만 아니라 액정 디스플레이 전체의 색 재현성을 향상시킬 수 있어 본 발명의 기술분야에서 매우 유용한 기술이다. According to the present invention, since the first and second polarizations of the specific region unreflected in the reflection layer are reflected by the first and second cholesteric liquid crystal layers, an even reflectance is obtained for the entire reflection region to be reflected and thus, Complement of the difference, which can improve the luminance as well as the color reproducibility of the entire liquid crystal display is a very useful technology in the technical field of the present invention.

Claims (12)

  1. 입사되는 광을 반사시키도록 백라이트 유닛에 구비된 반사판에 있어서,In the reflector provided in the backlight unit to reflect the incident light,
    입사되는 랜덤편광을 반사시키는 반사층, 상기 반사층의 일면에 배치되어 특Reflective layer for reflecting the incident random polarized light, disposed on one surface of the reflective layer
    정영역의 제1편광을 반사시키고 제2편광은 투과시키도록 이루어진 제1콜레스테릭 액정층, 상기 제1콜레스테릭 액정층을 투과한 특정영역의 제2편광을 반사시키도록 이루어진 제2콜레스테릭 액정층을 포함하며,A first cholesteric liquid crystal layer configured to reflect the first polarized light of the positive region and to transmit the second polarized light, and a second collet configured to reflect the second polarized light of the specific region transmitted through the first cholesteric liquid crystal layer A steric liquid crystal layer,
    상기 제1콜레스테릭 액정층과 제2콜레스테릭 액정층은 상기 반사층에서 반사The first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer are reflected by the reflective layer
    시키고자 하는 광의 임의 반사영역 중에서 반사층에 의한 반사율이 다른 영역의 파장보다 상대적으로 낮은 파장 범위에 속하는 편광에 대한 전반사를 유도하는 반사 파장대역을 갖는 것을 특징으로 하는 백라이트 유닛용 반사판.A reflection plate for a backlight unit, characterized in that it has a reflection wavelength band which induces total reflection for the polarization belonging to a wavelength range in which the reflectance of the reflective layer is relatively lower than the wavelength of other regions among the arbitrary reflection regions of light to be made.
  2. 청구항 1에 있어서,The method according to claim 1,
    상기 제1콜레스테릭 액정층은 중심파장이 상이한 수개의 콜레스테릭 액정이 적층되는 것을 특징으로 하는 백라이트 유닛용 반사판.The first cholesteric liquid crystal layer is a reflection plate for a backlight unit, characterized in that several cholesteric liquid crystals having different center wavelengths are stacked.
  3. 청구항 1 또는 청구항 2에 있어서,The method according to claim 1 or 2,
    상기 제2콜레스테릭 액정층은 중심파장이 상이한 수개의 콜레스테릭 액정이 적층되는 것을 특징으로 하는 백라이트 유닛용 반사판.The second cholesteric liquid crystal layer is a reflection plate for a backlight unit, characterized in that several cholesteric liquid crystals having different center wavelengths are stacked.
  4. 청구항 1에 있어서,The method according to claim 1,
    상기 제1콜레스테릭 액정층은 제1편광을 반사시키도록 하부에서 상부로 가면서 연속적으로 피치의 변화를 갖는 단일의 콜레스테릭 액정으로 이루어진 것을 특징으로 하는 백라이트 유닛용 반사판.The first cholesteric liquid crystal layer is a reflective plate for a backlight unit, characterized in that made of a single cholesteric liquid crystal having a pitch change continuously from the bottom to the top to reflect the first polarized light.
  5. 청구항 1 또는 청구항 4에 있어서,The method according to claim 1 or 4,
    상기 제2콜레스테릭 액정층은 제2편광을 반사시키도록 하부에서 상부로 가면서 연속적으로 피치의 변화를 갖는 단일의 콜레스테릭 액정으로 이루어진 것을 특징으로 하는 백라이트 유닛용 반사판.The second cholesteric liquid crystal layer is a reflection plate for a backlight unit, characterized in that made of a single cholesteric liquid crystal having a pitch change continuously from top to bottom to reflect the second polarized light.
  6. 청구항 1에 있어서,The method according to claim 1,
    상기 반사층은 콜레스테릭 액정층의 적어도 어느 일면으로 코팅된 반사물질로 이루어진 것을 특징으로 하는 백라이트 유닛용 반사판.The reflecting layer is a reflector for a backlight unit, characterized in that made of a reflective material coated on at least one side of the cholesteric liquid crystal layer.
  7. 청구항 1에 있어서,The method according to claim 1,
    상기 반사층은 베이스기재와, 상기 베이스기재의 적어도 일면으로 도포되는 반The reflective layer is half coated with a base substrate and at least one surface of the base substrate
    사물질을 포함하는 것을 특징으로 하는 백라이트 유닛용 반사판.Reflector for a backlight unit, characterized in that it comprises four substances.
  8. 청구항 6 또는 청구항 7에 있어서,The method according to claim 6 or 7,
    상기 반사물질은 금, 은, 구리, 니켈, 알루미늄, Tio2 중 선택된 적어도 어느 The reflective material is at least any one selected from gold, silver, copper, nickel, aluminum, and Tio2.
    하나로 이루어진 것을 특징으로 하는 백라이트 유닛용 반사판.Reflector for the backlight unit, characterized in that consisting of one.
  9. 청구항 1에 있어서,The method according to claim 1,
    상기 제1콜레스테릭 액정층과 제2콜레스테릭 액정층의 반사파장대역은 상기The reflected wavelength band of the first cholesteric liquid crystal layer and the second cholesteric liquid crystal layer is
    반사층의 임의 반사영역중 최단의 파장 이상 및 이 최단의 파장보다 150nm 긴 150 nm or more of the shortest wavelength and the shortest wavelength of any reflective region of the reflective layer
    파장 이하의 범위인 것을 특징으로 하는 백라이트 유닛용 반사판.The reflector for backlight units characterized by the below-wavelength range.
  10. 청구항 9에 있어서,The method according to claim 9,
    상기 임의 반사영역은 모든 가시광선 영역을 포함하며, 상기 제1콜레스테릭The random reflection region includes all visible light regions, and the first cholesteric
    액정층과 제2콜레스테릭 액정층의 반사파장대역은 자외선 영역과 경계를 이루The reflected wavelength band of the liquid crystal layer and the second cholesteric liquid crystal layer borders the ultraviolet region.
    는 가시광선 영역의 최단의 파장 이상 및 이 최단의 파장보다 150nm 긴 파장 이하Is not less than the shortest wavelength of the visible light region and not more than 150 nm longer than the shortest wavelength
    의 범위인 것을 특징으로 하는 백라이트 유닛용 반사판.Reflector for the backlight unit, characterized in that the range.
  11. 청구항 1, 청구항 2, 청구항 4, 청구항 6, 청구항 7, 청구항 9, 청구항 10 중 Claims 1, 2, 4, 6, 7, 7, and 10
    어느 한 항에 기재된 반사판을 갖는 백라이트 유닛.The backlight unit which has a reflector as described in any one of Claims.
  12. 청구항 11의 백라이트 유닛을 갖는 액정디스플레이.A liquid crystal display having the backlight unit of claim 11.
PCT/KR2010/003826 2009-06-17 2010-06-15 Reflective plate for backlight unit, backlight unit comprising the same and liquid crystal display WO2010147355A2 (en)

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