KR100621672B1 - Backlight unit by photoluminescent diffusion sheet - Google Patents

Abstract

The present invention absorbs a portion of light emitted from a light source having a blue wavelength or a wavelength in which at least one wavelength of blue and non-blue wavelengths is mixed to emit light having a wavelength different from that of the emitted light. A light-excited diffusion sheet for a backlight device that transmits the remaining portion of the light emitted from the light excitation sheet, the light-excitation diffusion sheet scatters the light excitation material for exciting and amplifying the light emitted from the light source, and the light emitted from the light source And a sheet in which the diffusing material to be diffused is uniformly mixed, wherein a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the photoexcited diffusion sheet, which is larger (if upper surface) or smaller (if lower surface) of the photoexcited diffusion sheet. A light excitation diffusion sheet for a backlight device, which is formed.

The light excitation diffuser sheet according to the present invention performs not only optical excitation but also diffusion and prism functions, and thus, the production cost is low and the color purity is not only high, but also the edge emission type and the direct emission type backlight having improved light efficiency by the optical amplification layer. An apparatus is provided.

LCD BLU, backlight unit, photoluminescent diffusion sheet, color conversion, optical amplification layer

Description

Optical excitation diffusion sheet for backlight device having optical amplification layer, backlight device for liquid crystal display using same {Backlight unit by photoluminescent diffusion sheet}

1 is a schematic cross-sectional view of a conventional edge-emitting backlight device

2 is a schematic cross-sectional view of a conventional direct light type backlight device.

Figures 3a to 3d is a schematic cross-sectional view of a light excitation diffuser sheet formed with an optical amplification layer of the present invention

Figures 4a to 4c is a schematic cross-sectional view of the edge-emitting backlight device to which the light-excited diffusion sheet formed with the optical amplification layer of the present invention is applied

5a to 5b are schematic cross-sectional views of a direct light emitting backlight device to which a light-excited diffusion sheet having an optical amplification layer of the present invention is applied;

Figure 6a is a schematic cross-sectional view of the edge-emitting bidirectional backlight device to which the light-excited diffusion sheet formed with the optical amplification layer of the present invention is applied

Figure 6b is a schematic cross-sectional view of a bi-directional backlight device of the direct emission method applying the light-excited diffusion sheet formed with the optical amplification layer of the present invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device used in a liquid crystal display device, and more particularly, to a backlight device for a liquid crystal display that can considerably reduce production costs and improve color reproducibility of a backlight by using a new diffusion sheet.

In general, the liquid crystal display does not form an image through self-emission, but is a light-receiving display in which light is incident from the outside to form an image, and thus the image cannot be observed in a dark place. The backlight device provided on the rear of the liquid crystal display device emits light so that the image can be observed even in a dark place. In addition to light-receiving displays such as liquid crystal displays, the backlight device is used for surface light source devices such as lighting signs.

Such a backlight device includes a direct light type in which a plurality of light sources installed directly below the liquid crystal panel directly irradiate light onto the liquid crystal panel according to the arrangement of the light sources, and a light source installed on the sidewall of the light guide panel. It can be classified as an edge light type (edge light type) that is irradiated to and delivered to the liquid crystal panel. The light source of the backlight device may be classified into an inorganic light emitting diode and a fluorescent lamp. The fluorescent lamp is a cold cathode fluorescent lamp (CCFL) in which electrodes at both ends are installed in a tube according to the shape of the electrode. And an external electrode fluorescent lamp (EEFL) in which electrodes at both ends are provided outside the tube.

FIG. 1 schematically shows a configuration of a backlight device for a liquid crystal display having a conventional edge-type light source, and schematically shows a configuration of guiding light emitted from the edge-type light source 11 and the light source 11. The light guide plate 12, the reflector plate 13 disposed below the light guide plate 12, the diffusion sheet 14 installed on the top of the light guide plate 12, and the prism installed in the vertical and horizontal directions on the top of the diffusion sheet 14. The sheet 15 and the protective sheet 16 installed on the prism sheet 15 are included. In addition, a light source cover 11a is provided outside the light source 11 of the backlight device.

FIG. 2 schematically illustrates a configuration of a backlight device for a liquid crystal display having a conventional direct type light source. The configuration includes a plurality of light sources 21 disposed at predetermined intervals and a reflector 22 disposed below the light source 21. , A protection plate (not shown) provided below the reflector 22, a diffusion sheet 24 installed above the light source 21, a prism sheet 25 installed above the diffusion sheet 24, and a protection sheet. (26).

1 and 2, when AC power is applied to the light sources 11 and 21, ultraviolet rays generated from the discharge gas by the discharge between the electrodes excite the phosphor layer to convert the light source into visible light. The converted light is guided through the light guide plate 12 to be reflected toward the reflector 13 (in case of FIG. 1) or partially reflected from the reflector 22 without passing through the light guide plate 12 (in case of FIG. 2). ). Subsequently, light is diffused through the diffusion sheets 14 and 24 and then irradiated to the liquid crystal panel via the prism sheets 15 and 25. The light source 11 of the edge light emission method (FIG. 1) mainly uses a white inorganic light emitting diode and a cold cathode fluorescent lamp, and the direct light emission type light source 21 of FIG. 2 mainly includes a cold cathode fluorescent lamp and an external electrode fluorescent lamp. Used.

The white inorganic light emitting diode of the edge light source 11 is composed of blue light emitted from a light emitting diode chip, which is a nitride semiconductor element, and a yttrium-aluminum-garnet fluorescent material applied on the semiconductor element. YAG-based phosphors) implements white light by mixing light of yellow light that absorbs a part of blue light and emits excitation light. However, since YAG-based phosphors such as Y3Al5O12: Ce are yellow and are mixed with blue, which is a complementary color, to realize white color, only YAG-based phosphors lack red light, which makes it difficult to realize perfect white. In addition, the white inorganic light emitting diode has a large amount of phosphors concentrated inside the reflecting cup of the lead terminal having a very small area, and since the phosphors are mostly concentrated around the inorganic light emitting diode chip, the transmittance of blue light is reduced to the extent required by the user. Not only is not easy to implement white light, but the brightness of the device itself is very poor. In addition, since the phosphor is not uniformly dispersed in the molding part, the color of the emitted light varies for each viewing angle of the light emitting element. In addition, when the output of the inorganic light emitting diode chip is increased, excessive heat is emitted and the phosphor is easily deteriorated, thereby reducing the luminance as well as the reliability of the light emitting device. For that reason, it is impossible to insert a multicolored phosphor around the inorganic light emitting diode chip.

Cold cathode fluorescent lamps, which are light sources used for edge emitting and direct emitting, form electrodes on both ends of fine glass tubes with a diameter of several mm, and contain mercury and inert gases (Ne, Ar) inside the glass tubes, like fluorescent lamps. It is a structure coated with a fluorescent material, but the internal electrode shape is different. Cold cathode fluorescent lamps were previously used in the form of rod-shaped electrodes. However, in order to increase efficiency and brightness, many cup-type electrodes are used.

The external electrode fluorescent lamp, which is a light source used for direct light emission, has a structure similar to that of a cold cathode fluorescent lamp, but does not have an electrode inside the glass tube, and attaches an electrode to the outside to prevent shortening of life due to electrode degradation. The brightness and efficiency vary depending on the length.

SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and an object of the present invention is to provide an edge light emission type and a direct emission type backlight device which use a new diffusion sheet, which is low in production cost, good in color purity, and improves light efficiency. To provide.

In order to achieve the above object, the present invention provides a liquid crystal display backlight device using a new sheet. The backlight device of the present invention includes an edge type backlight device and a direct type backlight device. It also includes both unidirectional and bidirectional directions of light from the light source.

The applicant of the present invention filed on December 24, 2004, application number 2004-111677 (light excitation diffusion sheet for a backlight device and a backlight device for liquid crystal display using the same). The present invention relates to a transparent sheet in which a light excitation material and a light diffusing material are uniformly mixed, and an application thereof to a backlight device. The present invention further relates to the refractive index of the sheet on the upper and lower surfaces of the sheet. Discloses that the efficiency of light is increased by forming a light amplification layer having different refractive indices. In order to explain the light-excited diffusion sheet of the present invention, the description of the present invention is partially introduced in the present specification.

The sheet used in the backlight device of the present invention absorbs a portion of light emitted from a light source having a blue wavelength or a wavelength at which at least one of a blue wavelength and a wavelength other than blue is mixed so that the sheet has a wavelength different from that of the emitted light. It is to emit light and to transmit the rest of the light emitted from the light source, the light excitation material to excite and amplify the light emitted from the light source, and the diffusion material to scatter and diffuse the light emitted from the light source In the form of a uniformly mixed transparent sheet, a transparent optical amplification layer is formed on the upper surface or / and the lower surface of the sheet is larger (if upper surface) or smaller (if lower surface) than the refractive index of the sheet. The optical amplification layer may be a multilayer or a single layer. In addition, the sheet includes a thin plate-like material (film) made of a polymer resin, a glass plate or the like.

Hereinafter, with reference to the accompanying drawings will be described in detail for the light-excited diffusion sheet of the present invention. For convenience of explanation, it will be described below assuming that the light-excited diffusion sheet is a sheet made of a polymer resin. As shown in FIGS. 3A to 3D, the photoexcited diffusion sheets 100, 100b, 100c, and 100d are largely composed of a photoexcitation material 30 that excites and amplifies the light and a diffusion material that scatters and diffuses the light ( 40) and a polymer resin 50 serving as a matrix so that the photoexcitation material and the diffusion material can be uniformly distributed. In addition, a precipitation inhibitor, an antifoaming agent, a binder, and the like are added during the manufacture of the sheet (film) in order to uniformly diffuse the substance or particles and to improve the formability of the sheet. In addition, the optical amplification layer (60a, 60b) is formed on the upper and / or lower surface of the optical excitation diffusion sheet (100, 100b, 100c, 100d) to improve the linearity and luminous efficiency of the light, and also serves as a protective film of the optical excitation diffusion sheet do. The optical amplification layers 60a and 60b are made of a material having a larger refractive index (upper surface) or smaller (lower surface) than the light-excited diffusion sheet in contact with the light-excited diffusion sheet. Although the optical amplification layers 60a and 60b are single layers in the drawing, as described above, the optical amplification layers 60a and 60b may be in contact with a plurality of layers. For example, an optical amplification layer (B) formed of a material having a large refractive index is formed on an adjacent layer of the upper surface of the optical excitation sheet, and is made of a material having a smaller refractive index than the optical amplification layer (A) below. May be formed alternately to form a multilayer. In addition, the optical amplification layer formed on the lower surface of the optical excitation diffusion sheet may also be configured in a multilayer. However, whether the optical amplification layer is a single layer or a multilayer, the layer immediately adjacent to the upper surface of the photoexcited diffusion sheet must be larger than the refractive index of the photoexcited diffusion sheet, and the layer immediately adjacent to the lower surface of the photoexcited diffusion sheet is It should be smaller than the refractive index of the diffusion sheet.

Optical excitation diffusion sheet

The photoexcitation material 30 that can be used in the present invention largely includes inorganic fluorescent materials, organic fluorescent materials, organic pigments, nanomaterials and the like. Representative photo-excited inorganic fluorescent materials are composed of phosphors doped with cerium (Y ₃ ) in Y ₃ Al ₅ O ₁₂ (YAG) in garnet-based (Gd) materials. Inorganic fluorescent materials that can be used in the present invention are specifically (Y _1-x-y Gd _x Ce _y ) ₃ (Al _1-z Ga _z ) ₅ O ₁₂ ; (Gd _1-x Ce _x ) Sc ₂ Al ₅ O ₁₂ ; (x + y ≦ 1; 0 ≦ x ≦ 1; 0 ≦ y ≦ 1; 0 ≦ z ≦ 1) SrB ₄ O ₇ : Sm ²⁺ ; SrGa ₂ S ₄ : Eu ²⁺ ; BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ; (Sr, Mg, Ca, Ba, Zn) ₂ P ₂ O ₇ : Eu, Mn; (Ca, Sr, Ba, Mg) ₅ (PO ₄ ) ₃ (Cl, F, OH): Eu, Mn; (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ (F, Cl, Br, OH): Eu ²⁺ ; (Sr, Ca, Ba, Mg) ₁₀ (PO ₄ ) ₆ (F, Cl, Br, OH): Eu ²⁺ , Mn ²⁺ ; (Sr, Ba, Ca) MgAl ₁₀ O ₁₇ : Eu, Mn; (Ba, Sr, Ca) MgAl ₁₀ O ₁₇ : Eu ²⁺ ; _{(Sr, Ca) 10 (PO} 4) 6 .nB 2 O 3: Eu 2+; ( stage, 0 <n <1) Sr 4 Al 14 O 25: Eu; 3.5MgO.0.5MgF ₂ .GeO ₂ : Mn ⁴⁺ ; ZnS: Cu, Al; ZnS: Ag, Al; CaS: Ce; SrS: Ce; SrS: Eu; MgS: Eu; CaS: Eu; (Y, Tb, Lu, La, Gd) ₃ (Al, Sc, Ga, In) ₅ O ₁₂ : Ce, Pr, Sm; BaAl ₈ O ₁₃ : Eu; 2SrO.0.84P ₂ O ₅ .0.16B ₂ O ₃ : Eu; Sr ₂ Si ₃ O ₈ .2SrCl ₂ : Eu; Ba ₃ MgSi ₂ O ₈ : Eu ²⁺ ; Sr ₄ Al ₁₄ O ₂₅ : Eu ²⁺ ; (Ba, Sr, Ca) Al ₂ O ₄ : Eu ²⁺ ; (Y, Gd, Lu, Sc, La) BO ₃ : Ce ³⁺ , Tb ³⁺ ; (Ba, Sr, Ca) ₂ SiO ₄ : Eu ²⁺ ; (Ba, Sr, Ca) ₂ (Mg, Zn) Si ₂ O ₇ : Eu ²⁺ ; (Sr, Ca, Ba) (Al, Ga, In) ₂ S ₄ : Eu ²⁺ ; (Y, Gd, Tb, La, Sm, Pr, Lu) _x (Al, Ga, In) _y O ₁₂ : Ce ³⁺ ; (2.82.8x≤3; 4.9≤y≤5.1) (Ca, Sr , Ba) ₈ (Mg, Zn) (SiO ₄ ) ₄ (Cl, F) ₂ : Eu ²⁺ , Mn ²⁺ ; (Gd, Y, Lu, La) ₂ O ₃ : Eu ³⁺ , Bi ³⁺ ; (Gd, Y, Lu, La) ₂ O ₂ S: Eu ³⁺ , Bi ³⁺ ; (Gd, Y, Lu, La) VO ₄ : Eu ³⁺ , Bi ³⁺ ; SrY ₂ S ₄ : Eu ²⁺ ; CaLa ₂ S ₄ : Ce ³⁺ ; (Ca, Sr) S: Eu ²⁺ ; (Ba, Sr, Ca) MgP ₂ O ₇ : Eu ²⁺ , Mn ²⁺ ; ZnCdS and the like and a mixture of two or more selected therefrom. The main wavelength of light emitted from the photoexcitation material depends on the excitation material described above. Ce ³⁺ emission depending on the garnet composition can emit light from green (~ 540 nm; YAG: Ga, Ce) to red (~ 600 nm; YAG: Gd, Ce) without decreasing the light efficiency. have. In addition, a representative inorganic phosphor for emitting deep red is SrB ₄ O ₇ : Sm ²⁺ . SM ²⁺ mainly contributes to the red wavelength. In particular, the deep red inorganic phosphor absorbs the entire visible light region of 600 nm or less and emits light having a deep red color, that is, a wavelength of 650 nm or more. A representative inorganic phosphor for emitting green light is SrGa ₂ S ₄ : Eu ²⁺ . Such a green inorganic phosphor absorbs light of 500 nm or less and emits a main wavelength of 535 nm. A representative inorganic phosphor for emitting blue light is BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ . Such a blue inorganic phosphor absorbs light of 430 nm or less and emits a main wavelength of 450 nm.

Organic fluorescent materials may emit blue, green, and red light. For example, (4,4'-bis (2,2-diphenyl-ethen-1-yl) diphenyl (DPVBi), bis (styryl) amine (DSA) system, and the like are typical organic materials emitting blue light. , Tris (8-quinolinato) aluminum (III) (Alq ₃ ), cumarin 6, 10- (2-benzothiazolyl) -1,1,7,7-tetramethyl-2,3,6 , 7-tetrahydro-1 H, 5 H, 11 H-[1] benzopyrano [6,7,8-ij] -quinolizine-11-one (C545T) and quinacridone luminesce green In addition, 4-dicyanomethylene-2-methyl-6- (zulolidin-4-yl-vinyl) -4H-pyran (DCM2) and 4- (dicyanomethylene) -2-methyl -6- (1,1,7,7-tetramethylzulolidil-9-enyl) -4H-pyran (DCJT), 4- (dicyanomethylene) -2-tertbutylbutyl-6- (1,1 , 7,7-tetramethylzulolidyl-9-enyl) -4H-pyran (DCJTB) and the like are representative organic substances that give a red color.

The organic pigments usable in the present invention include azo pigments such as insoluble azo pigments, azo lake pigments, condensed azo pigments and metal salt azo pigments. Examples of the phthalocyanine salts include copper phthalocyanine, halogenated copper phthalocyanine, metal phthalocyanine, and copper phthalocyanine lake pigments. Dye lake pigments include acid fuel lakes and basic dye lake pigments, and condensed polycyclic pigments include anthraquinone, thioindigo, perylene, prinon, quinacridone, dioxazine, isoindolinone, Isoindoline, quinaphthalone, and the like, and other pigments include nitroso pigments, alizarin, metal complex salt azomethine, aniline black, alkali blue, and fluorescence fluorescence.

Nano-scale metals and nano-composites are used as materials such as quantum dots of nano metals and composite materials. Platinum, gold, silver, nickel, magnesium, palladium, etc. are used as nano metals. Composite materials include cadmium sulfide (CdS), cadmium selenide (CdSe), zinc sulfide (ZnS), zinc selenide (ZnSe), indium phosphite (InP), titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin Oxides (SnO), silicon oxides (SiO ₂ ), magnesium oxides (MgO) and the like.

Diffusion material 40 of the present invention is largely divided into a transparent diffuser and a white diffuser. Transparent diffusing agents include organic transparent diffusing agents such as acrylic resins, styrene resins and silicone resins, and inorganic transparent diffusing agents such as synthetic silica, glass beads, and diamonds, and white diffusing agents include silicon oxide (SiO ₂ ) and titanium oxide (TiO _2). ), Inorganic oxides including zinc oxide (ZnO), barium sulfate (BASO ₄ ), calcium carbonate (CaSO ₄ ), magnesium carbonate (MgCO ₃ ), aluminum hydroxide (Al (OH) ₃ ), clay, etc. 40.

The polymer resin 50, which is a base material of the photoexcitation material 30 and the diffusion material 40, may be epoxy, urethane, acrylic, PET, polyvinyl chloride, polyester, polycarbonate, Vinyl, methacrylic ester, polyamide, synthetic lava, polystyrene, CBS, polymethyl methacrylate, fluororesin, polyethylene, polypropylene, ABS, Ferra resin, and the like.

In addition, when the film is manufactured using the photoexcitation material 30, the diffusion material 40, the resin 50, and the like, the film film is uniformly formed, and at the same time, the photoexcitation material 30, the diffusion material 40, and the like. In order to prevent the precipitation, it may include an anti-settling agent, an anti-foaming agent, a binder and the like so as not to generate bubbles.

The method of manufacturing the light-excited diffusion sheet (100, 100b, 100c, 100d) of the present invention is a mold method, extrusion method, exclusion method, suspension printing method, hot roll type coating (hot roll type), heat plate method (heat plate method) type) coating, cold type coating, screen printing, dip coating, display method, spin coating method, doctor braid, extrusion molding method, transfer method, lamination method, injection method, blowing method, calendering, mold, There are FRP molding, thermoforming, welding, and the like. Among them, extrusion printing and screen printing using a printing method are typical.

First, the synthetic resin is manufactured in a molten state, and then the light excitation material 30, the diffusing material 30, the precipitation inhibitor, the anti-foaming agent, the binder and the like are mixed uniformly. Fast cooling in the molten state results in relatively low crystallization, in which films with good formability can be produced. The shape of the film, ie crystallinity, crystal size, and crystal structure, have a great influence on the properties of the film. The ratio determines the strength, impermeability, and chemical resistance. The amorphous cross section determines the toughness and flexibility. The thickness of the film also greatly affects the cooling rate. Slow cooling in the molten state leads to high crystallinity. It is a ductile film but has good impermeability and high strength. Post-processing affects film cure, which may increase crystallinity during thermoforming and stretching.

When the extrusion molding using a mold can be produced a functional film. That is, as shown in FIG. 3B, when the cross-sectional shape of the sheet 100b is in the form of a sawtooth 125a, a sheet having excitation and diffusion functions as well as a prism function is obtained. In addition, as shown in FIG. 3C, the optical excitation and the diffusion materials 30 and 40 are distributed at the upper end of the sheet 100c, and the lower end 12c is formed in the form of a light guide sheet. Can be prepared. In addition, in the form 100d as shown in FIG. 3d, a sheet to perform light guide and prism functions is obtained. Therefore, since only one prism sheet needs to be used, not only the production cost may be reduced, but also the color purity of the backlight may be improved.

Optical amplification layer

The material of the optical amplification layer (60a, 60b) usable in the present invention is an organic material such as NPB, Alq3, CuPC, pentacene and LiF, SiO, SiO ₂ , TiO ₂ , Si ₃ N ₄ , ZnSe, ITO, IZO, Inorganic materials such as SiON, and transparent photoresist (PR). Also mixed forms thereof are possible. The material of the above optical amplification layer is exemplary. However, the constituent materials of the optical amplification layers 60a and 60b are determined according to the refractive indices of the optical excitation diffusion sheets 100, 100b, 100c and 100d. That is, when the optical amplification layer 60a is formed on the optical excitation diffusion sheets 100, 100b, 100c, and 100d, a material having a larger refractive index is selected as a material for forming the optical amplification layer 60a. When the optical amplification layer 60b is formed on the lower surface of the optical excitation diffusion sheets 100, 100b, 100c, and 100d, a material having a smaller refractive index is selected as a material for forming the optical amplification layer 60b. Lose. The above is a case where the optical amplification layer is a single layer, but may be a multilayer. That is, although not shown in the figure, for example, the refractive index of SiO is about 1.9 and the refractive index of SiO ₂ is about 1.4, which can be configured in multiple layers by alternating on the upper surface of the photoexcited diffusion sheet. (Diffusion sheet / SiO / SiO ₂ / SiO / SiO ₂ ...) The thickness of each layer may also be the same or different, and the number of layers, the thickness or total thickness of each layer is related to the refractive index of the formed material.

Forming the optical amplification layer (60a, 60b) on the upper or lower surface of the sheet (100, 100b, 100c, 100d) is a known method such as vacuum deposition, screen printing, photolithography after fabrication of the optical excitation sheet To form.

LCD backlight unit

Hereinafter, an embodiment of a liquid crystal display backlight device constructed using the optically excited diffusion sheet having the optical amplification layer described above will be described. Figure 4a shows a backlight of the edge type light emission method. The light emitted from the blue inorganic light emitting diode as the light source 111 or the cold cathode fluorescent lamp as the linear light source is guided through the light guide sheet 112 to be turned into a surface light source or partially reflected by the reflector plate 113 so that the light is excited. Go to 100. In this case, an optical amplification layer 60b having a refractive index smaller than the refractive index of the optical excitation diffusion sheet 100 is formed on a lower surface of the optical excitation diffusion sheet 100, and the light has a luminance by the optical amplification layer 60b. It is incident on the photoexcited diffusion sheet 100 in an increased state. The blue light entering the photoexcited diffusion sheet 100 is partially transmitted, and part of the blue light is changed into light of various colors such as green, yellow, and red by the light excitation material in the photoexcited diffusion sheet 100. Optical amplification. In addition, the light is scattered and diffused by the diffusion material in the light excitation diffusion sheet 100 to improve the uniformity of the light. The light exiting the light excitation diffusion sheet 100 is improved once again by the optical amplification layer 60a formed thereon, thereby becoming white light. When the light reaches the horizontal and vertical prism sheet 115 through the light excitation diffusion sheet 100, the light is refracted by scattered or diffused light, and condensed to further improve luminance. Through this process, light is irradiated to the liquid crystal display through the protective sheet 116.

In FIG. 4A, the photoexcited diffusion sheet may be replaced with the sheet 100b having the form of FIG. 3B. The structural example which employ | adopted the light-excitation-diffusion sheet 100b which has the form of FIG. 3B is shown in FIG. 4B. However, since the light-excited diffusion sheet 100b having the shape of FIG. 3B performs a prism function, a separate horizontal prism 115a as shown in FIG. 4A is unnecessary. Furthermore, in FIG. 4A, the photoexcited diffusion sheet may be replaced with the photoexcited diffusion sheets 100c and 100d of FIG. 3C or 3D, and the photoexcited diffusion sheets 100c and 100d may perform light guiding functions. A separate light guide sheet 112 as in FIG. 4A or 4B is unnecessary. Furthermore, when the light excitation diffusion sheet 100d having the shape as shown in FIG. 3D is employed (FIG. 4C), the light guide and prism functions are performed, so that a separate horizontal prism 115a as shown in FIG. 4A is unnecessary.

Preparation of Light Excited Diffusion Sheet

7% silicon oxide ball by weight, 4.99% YAG and 0.01% 4- (dicyanomethylene) -2-tert-butylbutyl-6- (1,1,7,7-tetramethyljoule Lorridyl-9-enyl) -4H-pyran (DCJTB) was mixed with 88% epoxy resin and mixed for about 20 minutes at room temperature in an ultrasonic cleaner. The mixed solution was constantly added to the mold mold to which the release agent was applied, and then left and right equilibrium was constantly operated by a horizontal gauge and left for about 10 minutes. Using a hot plate was cured at about 125 ℃ for 1 hour, left for about 30 minutes at room temperature and then re-cured and peeled at 125 ℃ for 3 hours in an oven to prepare a photo-excited diffusion sheet.

The optical amplification layer was formed by depositing silicon oxide (SiO) to an average thickness of 100 nm on the upper surface of the fabricated photoexcited diffusion sheet by vacuum thermal evaporation.

The table below shows the results of comparing and measuring the luminous efficiency (luminance) of the light-excited diffusion sheet and the light-excited diffusion sheet in which the optical amplification layer is not formed. The configuration of the backlight device is as shown in FIG. 4A. However, the optical amplification layer 60a is formed only on the upper portion of the light-excited diffusion sheet 100.) As the luminance measuring device, CS-1000A manufactured by Minolta was used.

division Company A Blue Inorganic LED (cd / m ² ) Company B blue inorganic LED (cd / m ² ) Remarks Comparative product 1 733 1712 Manufactured by optical excitation sheet PS Invention 1 764 1800 Comparative product 2 602 1334 Made of light-excited diffusion sheet PMMA Invention 2 621 1446

As can be seen in the above table, according to the present invention it can be seen that the optical excitation diffusion sheet formed with an optical amplification layer is increased by up to 8.4% than the conventional optical excitation diffusion sheet.

The above is the case where the light source is unidirectional, and the schematic configuration of the bidirectional case is shown in Figs. 6A and 6B. That is, as shown in FIG. 6A, the edge type light source 151, the light guide sheet 152 for guiding light emitted from the light source, and the light amplification layers 60a and 60b around the light guide sheet 152. The light excitation diffuser sheet 100, the prism sheet 155, and the protective sheet 156 formed on the upper and lower surfaces thereof may be sequentially installed symmetrically in the upper and lower directions of the light guide sheet 152.

In addition, in the configuration of FIG. 6A, a partial reflection sheet (not shown) that reflects a part of light guided by the light guide sheet 152 and passes a part may be installed on one side or both sides of the light guide sheet 152. will be.

In addition, as illustrated in FIG. 6B, a light excitation diffuser sheet 100, a prism sheet 255, and a protective sheet having upper and lower direct light sources 251 and optical amplification layers 60a and 60b formed around the light source 251. 256 may be configured to be sequentially installed symmetrically in the upper and lower direction of the light source 100. Similarly, in the configuration of FIG. 6B, a partial reflection sheet (not shown) reflecting a part of light emitted from the light source 251 and passing a part thereof may be installed on one side or both sides of the light source 251.

In addition, in the bidirectional backlight device of FIGS. 6A and 6B, the upper and lower photoexcited diffusion sheets 100 may have different configurations.

According to the present invention as described above, the following effects can be obtained. The optical amplification layer is formed on the upper and lower surfaces of the light-excited diffusion sheet to further increase the luminous efficiency.

Claims (13)

Absorbs a portion of light emitted from a light source having a blue wavelength or a wavelength in which at least one of a blue wavelength and a wavelength other than blue is mixed to emit light having a wavelength different from that of the emitted light, and A light-excited diffuser sheet for a backlight device that transmits the rest of the light The photoexcited diffusion sheet is uniformly mixed with a light excitation material for exciting and amplifying the light emitted from the light source, and a diffusing material for scattering and diffusing the light emitted from the light source, An optical excitation layer for a backlight device, characterized in that a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the optically excited diffuser sheet, in which the refractive index of the optically excited diffuser sheet is larger (if upper surface) or smaller (if lower surface). Diffusion sheet. An edge type light source having a wavelength of at least one of a blue wavelength or a mixture of blue and blue wavelengths, a light guide sheet for guiding light emitted from the light source, a reflective sheet provided under the light guide sheet, and the light guide A backlight device for liquid crystal display comprising a light-excited diffusion sheet provided on an upper part of a sheet, a horizontal and vertical prism sheet provided on an upper part of the diffusion sheet, and a protective sheet provided on an upper part of the prism sheet. The light excitation diffusion sheet absorbs a portion of the light emitted from the light source to emit light having a wavelength different from that of the emitted light, and transmits the remaining portion of the light emitted from the light source. A sheet having a uniform mixture of a light excitation material for exciting and amplifying light emitted from the light and a diffusing material for scattering and diffusing the light emitted from the light source, A liquid crystal display backlight device, wherein a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the light-excited diffusion sheet, in which the refractive index of the light-excited diffusion sheet is larger or smaller than the upper surface. . An edge-type light source having a wavelength of blue or a mixture of at least one of a blue wavelength and a wavelength other than blue, and different from the wavelength of the emitted light by guiding light emitted from the light source and absorbing a portion of the guided light A light excitation diffusion sheet which emits light having a wavelength and transmits the remaining portion of the light emitted from the light source, horizontal and vertical prism sheets provided on the light excitation diffusion sheet, and a protection provided on the prism sheet A backlight device for liquid crystal display comprising a sheet, The light-excited diffusion sheet includes a light guide portion having a lower surface thereof inclined upwardly from the light source, an optical excitation material for exciting and amplifying light emitted from the light source, and a diffusion material for scattering and diffusing light emitted from the light source. Filling unit uniformly mixed is a sheet formed on the light guide portion, A liquid crystal display backlight device, wherein a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the optically excited diffusion sheet, in which the refractive index of the optically excited diffusion sheet is larger (if upper surface) or smaller (if lower surface). . An edge type light source having a wavelength of at least one of a blue wavelength or a mixture of blue and blue wavelengths, a light guide sheet for guiding light emitted from the light source, a reflective sheet provided under the light guide sheet, and the light guide A backlight device for a liquid crystal display comprising a light-excited diffusion sheet provided on an upper part of a sheet, a vertical prism sheet provided on an upper part of the diffusion sheet, and a protective sheet provided on an upper part of the vertical prism sheet. The light excitation diffusion sheet absorbs a portion of the light emitted from the light source to emit light having a wavelength different from that of the emitted light, and transmits the remaining portion of the light emitted from the light source. A sheet in which the photoexcitation material that excites and amplifies the light emitted from and the diffusion material that scatters and diffuses the light emitted from the light source is uniformly mixed. The cross section of the upper surface in contact with the vertical prism sheet has a sawtooth shape. A liquid crystal display backlight device, characterized in that a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the photoexcited diffusion sheet, in which the refractive index of the photoexcited diffusion sheet is larger or smaller than the upper surface. . An edge type light source having a wavelength of at least one of a blue wavelength or a mixture of blue and blue wavelengths, and a wavelength of the emitted light by absorbing a portion of the guided light guided by the light emitted from the light source; A light-excited diffusion sheet for emitting light of a different wavelength and transmitting the remaining portion of the light emitted from the light source, a vertical prism sheet installed on the light-excited diffusion sheet, and a protection provided on the vertical prism sheet A backlight device for liquid crystal display comprising a sheet, The light-excited diffusion sheet may include a light guide portion having a lower surface inclined upwardly from the light source, an optical excitation material for exciting and amplifying light emitted from the light source, and a diffusion material for scattering and diffusing light emitted from the light source. The uniformly mixed filling part is a sheet formed on the light guide portion, the cross section of the upper surface in contact with the vertical prism sheet is serrated, A liquid crystal display backlight device, characterized in that a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the photoexcited diffusion sheet, in which the refractive index of the photoexcited diffusion sheet is larger or smaller than the upper surface. . A direct type light source having a wavelength of at least one of a blue wavelength or a blue wavelength and a wavelength other than blue, a reflecting sheet provided below the light source, a light-exciting diffusion sheet provided above the light source, and the light excitation A liquid crystal display backlight device comprising horizontal and vertical prism sheets provided on an upper part of a diffusion sheet and a protective sheet provided on an upper part of the prism sheet. The light-excited diffusion sheet absorbs a portion of the light emitted from the light source to emit light having a wavelength different from that of the emitted light, and transmits the remaining portion of the light emitted from the light source. A sheet having a uniform mixture of a light excitation material for exciting and amplifying the light emitted from the light source and a diffusing material for scattering and diffusing the light emitted from the light source, A liquid crystal display backlight device, characterized in that a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the photoexcited diffusion sheet, in which the refractive index of the photoexcited diffusion sheet is larger or smaller than the upper surface. . A direct type light source having a wavelength of at least one of a blue wavelength or a blue wavelength and a wavelength other than blue, a reflecting sheet provided below the light source, a light-exciting diffusion sheet provided above the light source, and the light excitation A liquid crystal display backlight device comprising a vertical prism sheet provided on an upper portion of a diffusion sheet and a protective sheet provided on an upper portion of the prism sheet. The light excitation diffusion sheet absorbs a portion of the light emitted from the light source to emit light having a wavelength different from that of the emitted light, and transmits the remaining portion of the light emitted from the light source. A sheet in which a light excitation material for exciting and amplifying light emitted from and a diffusing material for scattering and diffusing light emitted from the light source is uniformly mixed, wherein a cross section of an upper surface of the upper surface in contact with the prism sheet is serrated. A liquid crystal display backlight device, characterized in that a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the photoexcited diffusion sheet, in which the refractive index of the photoexcited diffusion sheet is larger or smaller than the upper surface. . The liquid crystal display backlight device according to any one of claims 1 to 7, wherein the optical amplification layer is a multilayer. Edge type light source having a wavelength of at least one of a blue wavelength or a mixture of blue and non-blue wavelengths, a light guide sheet for guiding light emitted from the light source, and a light-excited diffusion sheet centered on the light guide sheet, horizontal and vertical A prism sheet and a protective sheet are bidirectional backlight devices for liquid crystal display in which the light guide sheets are sequentially installed in the upper and lower directions of the light guide sheet. The light-excited diffusion sheet absorbs a portion of the light emitted from the light source to emit light having a wavelength different from that of the emitted light, and transmits the remaining portion of the light emitted from the light source. Luminous light from the excitation and increase It is a sheet in which the light excitation material to be expanded and the diffusion material to scatter and diffuse the light emitted from the light source are uniformly mixed, A backlight for bidirectional liquid crystal display, wherein a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the photoexcited diffusion sheet, in which the refractive index of the photoexcited diffusion sheet is larger or smaller than the upper surface. Device. Edge type light source having a wavelength of at least one of a blue wavelength or a mixture of blue and blue wavelengths, a light guide sheet for guiding light emitted from the light source, a light excitation diffusion sheet and a vertical prism sheet centering on the light guide sheet And a protective sheet sequentially installed symmetrically in the upper and lower directions of the light guide sheet. The light excitation diffusion sheet absorbs a portion of the light emitted from the light source to emit light having a wavelength different from that of the emitted light, and transmits the remaining portion of the light emitted from the light source. A sheet in which the photoexcitation material that excites and amplifies the light emitted from and the diffusion material that scatters and diffuses the light emitted from the light source is uniformly mixed. The cross section of the upper surface in contact with the vertical prism sheet has a sawtooth shape. A backlight for bidirectional liquid crystal display, wherein a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the photoexcited diffusion sheet, in which the refractive index of the photoexcited diffusion sheet is larger or smaller than the upper surface. Device. A direct type light source having a wavelength of blue or at least one of a mixture of blue and non-blue wavelengths, a light-exciting diffusion sheet, a horizontal and vertical prism sheet, and a protective sheet in the upper and lower directions of the light source. A bidirectional backlight device for liquid crystal display that is sequentially installed symmetrically, The light-excited diffusion sheet absorbs a portion of the light emitted from the light source to emit light having a wavelength different from that of the emitted light, and transmits the remaining portion of the light emitted from the light source. A sheet having a uniform mixture of a light excitation material for exciting and amplifying the light emitted from the light source and a diffusing material for scattering and diffusing the light emitted from the light source, A backlight for bidirectional liquid crystal display, wherein a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the photoexcited diffusion sheet, in which the refractive index of the photoexcited diffusion sheet is larger or smaller than the upper surface. Device. A direct type light source having a wavelength of blue or a mixture of at least one of blue and non-blue wavelengths, a light excitation sheet, a vertical prism sheet, and a protective sheet symmetrically in the upper and lower directions of the light source. A bidirectional backlight device for liquid crystal display sequentially installed in The light excitation diffusion sheet absorbs a portion of the light emitted from the light source to emit light having a wavelength different from that of the emitted light, and transmits the remaining portion of the light emitted from the light source. A sheet in which the photoexcitation material that excites and amplifies the light emitted from and the diffusion material that scatters and diffuses the light emitted from the light source is uniformly mixed. The cross section of the upper surface in contact with the vertical prism sheet has a sawtooth shape. A backlight for bidirectional liquid crystal display, wherein a transparent optical amplification layer is formed on the upper surface and / or the lower surface of the photoexcited diffusion sheet, in which the refractive index of the photoexcited diffusion sheet is larger or smaller than the upper surface. Device. The backlight device according to any one of claims 9 to 12, wherein the optical amplification layer is a multilayer.

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