WO2015102295A1

WO2015102295A1 - Diffusion sheet and display using same

Info

Publication number: WO2015102295A1
Application number: PCT/KR2014/012795
Authority: WO
Inventors: 김돌; 김태호; 최운석; 이성형; 조성대; 신희선
Original assignee: 미래나노텍(주)
Priority date: 2013-12-31
Filing date: 2014-12-24
Publication date: 2015-07-09
Also published as: KR102214924B1; KR20150080208A

Abstract

The present invention relates to a diffusion sheet and a display using the same and, more specifically, to a diffusion sheet for improving luminance by diffusing light projected from a light source, and a display using the same. One embodiment of the present invention comprises: a base layer through which light passes; a first particle scattering layer which is formed on one surface of the base layer and comprises a light-transmitting resin containing a plurality of first particles; a pattern layer comprising a pattern formed on the first particle scattering layer; and a second particle scattering layer which is formed on the other surface of the base layer and comprises a coating layer containing a plurality of second particles having a different shape from the first particles.

Description

Diffusion sheet and display device applying the same

The present invention relates to a diffusion sheet and a display device employing the same, which is a diffusion sheet for diffusing light emitted from a light source to improve luminance, and a display device employing the same.

Unlike other display devices, a liquid crystal display device is not a light emitting material that emits light by itself but a liquid crystal material injected between a thin film transistor (TFT) substrate and a color filter. Therefore, a separate device for irradiating light to the liquid crystal material, that is, a backlight assembly is necessarily required.

1 is a cross-sectional view showing the configuration of a conventional liquid crystal display device.

The liquid crystal display device 1 includes a backlight assembly 10 for generating light and a display unit 20 provided on the backlight assembly 10 and receiving light from the backlight assembly 10 to display an image. .

The display unit 20 includes a liquid crystal display panel 25, an upper polarizing plate 24 positioned above and below the liquid crystal display panel 25, and a lower polarizing plate 21. The liquid crystal display panel 25 includes a TFT substrate 22 and a color filter substrate 23 having electrodes formed thereon, and a liquid crystal layer (not shown) injected between the TFT substrate and the

color filter substrates

22 and 23.

The backlight assembly 10 may include a mold frame (not shown) in which a storage space is formed, a reflection sheet 12 installed on a bottom surface of the storage space to reflect light toward the liquid crystal display panel, and a light guide on the upper surface of the reflection sheet. The optical sheet 17 which is installed between the light guide plate 13, the light guide plate 13 and the side wall of the storage space, and is laminated on the upper surface of the light guide plate 13 and the light guide plate 13 to diffuse and collect light. A top chassis (not shown) disposed on the mold frame and covering an area from the predetermined position of the edge of the liquid crystal display panel to the side surface of the mold frame.

Here, the optical sheets 17 may include a diffusion sheet 14 for diffusing light and a prism sheet 15 condensing and diffusing the light diffused and stacked on the upper surface of the diffusion sheet 14 to the liquid crystal display panel 25. ) And a protective sheet 16 for protecting the diffusion sheet 14 and the prism sheet 15. In this way, the optical sheets 17 applied to the backlight assembly have a composite sheet structure in which two or three sheets are laminated to form one sheet. Such composite sheets are in the spotlight in the market due to effects such as thinning, shielding ability, high brightness, and reduced number of processes.

By the way, the optical sheets 17 of the composite sheet use two or three pieces of fabrics in the manufacturing process to increase the unit cost according to the price of the fabrics, and a process of bonding several sheets is indispensable. There is a problem that causes the occurrence of phase defects.

(Prior art document) Korea Patent Publication 10-2010-0057483

The technical problem of the present invention is to implement a composite sheet of several sheets of optical sheets into a single diffusion sheet. In addition, the technical problem of the present invention is to improve the scattering effect of the diffusion sheet.

Embodiments of the present invention include a base layer for transmitting light; A first particle scattering layer formed on one surface of the base layer and including a translucent resin containing a plurality of first particles; A pattern layer including a pattern formed on the first particle scattering layer; And a second particle scattering layer formed on the other surface of the base layer, the second particle scattering layer including a coating layer containing a plurality of second particles having a shape different from that of the first particles.

The refractive index of the first particles is characterized in that greater than the refractive index of the translucent resin.

The refractive index of the light-transmissive resin has a range of 1.3 to 1.75, the refractive index of the first particles of the first particle scattering layer comprises a range of 1.4 ~ 1.8.

The refractive index of the pattern layer is characterized in that it is equal to or larger than the refractive index of the translucent resin.

The refractive index of the pattern layer has a range of 1.3 to 1.8, the refractive index of the translucent resin includes a range of 1.3 to 1.75.

The average particle diameter of the first particle and the second particle includes different ones.

The plurality of first particles may be formed to have the same size alternatively selected within 0.5 μm to 25 μm, or to different sizes within 0.5 μm to 25 μm.

The particle diameter of the second particle includes that formed to a size within 1nm ~ 500㎛.

The first particles may have any one of a core shell shape, a hollow shape, a biconvex shape, and a flake shape, and the second particles may be formed of a core shell shape, a hollow shape, a biconvex shape, and a flake shape. It includes one having the shape of the other.

The pattern layer includes a prism having a pitch of 5 μm to 200 μm, a lens, a triangular pyramid, a circular pyramid, a polygonal pyramid, and a lenticular type shape.

An embodiment of the present invention includes a display unit for displaying an image; A lamp unit for generating light; A light guide plate for guiding light generated by the lamp unit; And a single diffusion sheet for diffusing the light guided by the light guide plate toward the display unit. It includes, The diffusion sheet, the base layer for transmitting light; A first particle scattering layer formed on one surface of the base layer and including a translucent resin containing a plurality of first particles; A pattern layer including a pattern formed on the first particle scattering layer; And a second particle scattering layer formed on the other surface of the base layer and including a plurality of second particles having a shape different from that of the first particles.

The refractive index of the pattern layer is the same as or larger than the refractive index of the light-transmissive resin, and the refractive index of the first particle comprises a greater than the refractive index of the light-transmissive resin.

The refractive index of the pattern layer has a range of 1.3 to 1.8, the refractive index of the translucent resin has a range of 1.3 to 1.75, the refractive index of the first particles of the first particle scattering layer comprises 1.4 ~ 1.8.

A first average particle diameter, which is an average particle diameter of the first particles, and a second average particle size, which is an average particle diameter of the second particles, may be different from each other.

The first average particle diameter of the first particles includes an alternative single size within 0.5 μm to 25 μm, or different sizes within 0.5 μm to 25 μm.

According to the embodiment of the present invention, by implementing a single diffuser sheet of various functions, it is possible to reduce the manufacturing cost since it is not necessary to use several sheets. In addition, the failure rate can be reduced because several sheets are not bonded. In addition, by using a single diffusion sheet having a first particle, a second particle, and a pattern layer having a different average particle diameter, it is possible to maximize scattering efficiency and luminance increase effect.

2 is a cross-sectional view illustrating a configuration of a display device according to an exemplary embodiment of the present invention.

3 is a cross-sectional view of the diffusion sheet according to the embodiment of the present invention.

4 is a view showing a light refraction state in the diffusion sheet according to the embodiment of the present invention.

5 is a microscopic view of various particles according to an embodiment of the present invention.

Figure 6 is a table showing the brightness, shielding power, coating properties according to the shape combination of the first and second particles according to an embodiment of the present invention.

7 and 8 are tables showing the brightness, shielding power, coating properties according to the combination of the shape and size of the first and second particles according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Like numbers refer to like elements in the figures.

Hereinafter, a liquid crystal display device will be used as an example of the display device, and the backlight assembly will be described using an edge type light source as an example, but the same may be applied to the direct type light source.

Referring to FIG. 2, the liquid crystal display includes a backlight assembly 100 that generates light and a display unit 200 that is provided above the backlight assembly 100 and receives light from the backlight assembly 100 to display an image. ) Is included. The backlight assembly 100 includes a lamp unit 110 for generating light and

light guide units

120 and 130 for guiding the light generated by the lamp unit 110 to the liquid crystal display panel 250. In addition, the display unit 200 includes a liquid crystal display panel 250, an upper polarizing plate 240 positioned above and below the liquid crystal display panel 250, and a lower polarizing plate 210. The liquid crystal display panel 250 includes a TFT substrate on which electrodes are formed,

color filter substrates

220 and 230, and a liquid crystal layer (not shown) injected between the TFT substrate and

color filter substrates

220 and 230.

The lamp unit 110 includes a lamp 110a for generating light and a lamp reflector 110b surrounding the lamp 110a. The light generated from the lamp 110a is incident to the light guide plate 130, which will be described later, and the lamp reflector 110b is incident to the light guide plate 130 by reflecting the light generated from the lamp 110a to the light guide plate 130. It serves to increase the amount of light that becomes. The light guide unit includes a reflecting plate 120, a light guide plate 130, and a diffusion sheet 140, and the light guide plate 130 is provided at one side of the lamp unit 110 to guide light from the lamp unit 110. Play a role. In addition, a reflector 120 is provided below the light guide plate 130 to reflect the light leaked from the light guide plate 130 back to the light guide plate 130.

Meanwhile, a diffusion sheet 140 is provided on the light guide plate 130 to improve the efficiency of the light guided by the light guide plate 130. The diffusion sheet 140 scatters the light incident from the light guide plate 130 to uniform the luminance distribution of the light.

The diffusion sheet 140 according to the embodiment of the present invention is a single sheet in which the second particle scattering layer 141, the base layer 142, the first particle scattering layer 143, and the pattern layer 144 are sequentially formed. Is done. That is, the first particle scattering layer 143 which is formed on the base layer 142 and one surface of the base layer 142 and is formed of the first particles 143a in the same translucent resin 143b as the base layer 142. And a pattern layer 144 having a pattern formed on an outer surface of the first particle scattering layer 143 facing the surface in contact with the base layer 142, and a second particle formed on the other surface of the base layer 142. It includes a second particle scattering layer 141 made of a coating layer of (141a).

The diffusion sheet 140 condenses the light diffused by the second particle scattering layer 141 and the first particle scattering layer 143 in a direction perpendicular to the plane of the liquid crystal display panel, and thus, the diffusion sheet 140. Most of the light passing through the pattern layer 144 may be perpendicular to the plane of the liquid crystal display panel to have a uniform luminance distribution. Hereinafter, the diffusion sheet 140 according to the embodiment of the present invention will be described.

3 is a diagram showing the configuration of a diffusion sheet 140 according to an embodiment of the present invention.

(1) Base layer

The base layer 142 is made of a light transmissive substrate. Such a light-transmissive substrate may be a light-transmitting resin such as PET (PolyEthylene Terephthalate), PMMA (PolyMethyMethAcrylate) PEN (PolyEthylene Naphthalate), PP (PolyPropylene), PC (PolyCarbonate), TAC (TriAetyl Cellulose) resin, but is not limited thereto. .

(2) first particle scattering layer

The first particle scattering layer 143 includes a translucent resin 143b and first particles 143a which are scattering particles for controlling the refractive index. The first particle scattering layer 143 is a layer formed using an ultraviolet curable coating resin having a nonvolatile component of 5 to 100 wt% in the total weight ratio. The shape of the first particle 143a is defined as a second particle scattering layer ( The shape of the second particles 141a of 141 is different.

Hereinafter, the translucent resin 143b and the first particles 143a which are scattering particles will be described in detail.

Translucent resin

As the material of the light-transmissive resin 143b, a resin cured by at least one of ultraviolet rays, electron beams, and heat is mainly used. More specifically, at least one of three types of resins, namely, a photocurable resin, an ionizing radiation curable resin, and a thermosetting resin may be used, but PET, PEN, PP, PC, TAC, etc. may be used, but are not limited thereto. Do not. In addition, for these curable resins, a mixture of a thermoplastic resin and a solvent may be used.

The translucent resin 143b is preferably a polymer having a saturated hydrocarbon or polyether as a main chain, and more preferably a polymer having a saturated hydrocarbon as a main chain. In addition, it is preferable that the translucent resin 143b is bridge | crosslinked. It is preferable that the polymer which has a saturated hydrocarbon as a principal chain is obtained by the polymerization reaction of an ethylenically unsaturated monomer. In order to obtain a crosslinked binder, it is preferable to use a monomer having two or more ethylenically unsaturated groups as the material.

Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohols with (meth) acrylic acid (for example, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, pentaerythritol tetra ( Meta) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol Penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,3,5-cyclohexanetriol trimethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene derivative ( For example, 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (e.g. divinyl sulfone), acrylamide (Eg, methylenebisacrylamide), and methacrylamide. Among these, an acrylate or methacrylate monomer having at least three functional groups is preferable, and an acrylate monomer having at least five functional groups is more preferable from the viewpoint of film hardness, that is, scratch resistance. A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate is commercially available and is particularly preferred.

The monomer having an ethylenically unsaturated group can be dissolved in a solvent together with various polymerization initiators and other additives, and after coating and drying, polymerization can be carried out under ultraviolet light, ionizing radiation or heating to cure the coating.

Instead of or in addition to the polymerization of monomers having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the matrix by reaction of the crosslinkable groups. Examples of the crosslinkable functional group include an isocyanate group, an epoxy group, an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group and an active methylene group. Further, metal alkoxides such as vinylsulfonic acid, acid anhydrides, cyanoacrylate derivatives, melamines, etherified methylols, esters, or urethanes and tetramethoxysilanes may also be used as monomers for introducing the crosslinked structure. In addition, functional groups exhibiting crosslinkability as a result of the decomposition reaction may be used, such as blocked isocyanate groups. That is, the crosslinkable functional group used for this invention is not limited to the functional group which causes an immediate reaction, It may be a group which shows the reactivity after decomposition. The crosslinked structure can be formed by coating and then heating the matrix having such a crosslinkable functional group.

In addition to the matrix polymer described above, a monomer having a high refractive index may be added to the translucent resin 143b. Examples of the monomer having a high refractive index include bis (4-methacryloylthiophenyl) sulfide, vinylnaphthalene, vinylphenyl sulfide, and 4-methacryloxyphenyl-4'-methoxyphenylthioether. .

Examples of the solvent include ethers having 3 to 12 carbon atoms, specifically dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane , 1,3,5-trioxane, tetrahydrofuran, anisole and phentol; Ketones having 3 to 12 carbon atoms, specifically, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl cyclohexanone and methyl cyclohexanone; Esters having 3 to 12 carbon atoms, specifically, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate and γ-buty Rockactone; And organic solvents having at least two functional groups, specifically methyl 2-methoxyacetate, methyl 2-ethoxyacetate, methyl 2-ethoxyacetate, ethyl 2-ethoxypropionate, 2-methoxyethanol, 2 Propoxyethanol, 2-butoxyethanol, 1,2-diacetoxyacetone, acetylacetone, diacetone alcohol, methyl acetoacetate and ethyl acetoacetate. Other examples of solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol, cyclohexanol, isobutyl acetate , Methyl isobutyl ketone, 2-octanone, 2-pentanone, 2-hexanone, 2-heptanone, 3-pentanone, 3-heptanone, and 4-heptanone. One of these solvents may be used alone, or two or more thereof may be used in combination.

As a method for forming the light transmitting resin 143b, a coating method may be used. For example, the light transmissive resin 143b is coated on the base layer 142 by a bar coater or a spin coater.

As a method of hardening an ionizing radiation curable resin composition, the normal hardening method with respect to an ionizing radiation curable resin composition, ie, hardening by irradiation of an electron beam or an ultraviolet-ray, can also be used. For example, in the case of electron beam curing, various electron beams such as Cockroft-Walton type, Van de Graff type, resonant transformer type, insulation core transformer type, straight type, dynamtron type and high frequency type It is also possible to use an electron beam having an energy of 50 to 1,000 KeV, preferably 100 to 300 KeV, emitted from the accelerator, and for ultraviolet curing, ultra high pressure mercury lamp, high pressure mercury lamp, low pressure mercury lamp, carbon arc, xenon arc, metal halide lamp Ultraviolet rays emitted from light rays such as these may be used.

The refractive index of the translucent resin 143b is preferably implemented to have a refractive index of 1.3 to 1.75. In order to improve diffusion efficiency, the refractive index of the light transmissive resin 143b should be smaller than the refractive index of the pattern layer 144 and should be smaller than the refractive index of the first particle 143a.

First particle

The kind of the first particles 143a which are the scattering particles constituting the first particle scattering layer 143 is not limited, and may be organic fine particles or inorganic fine particles. Examples of organic particulates include polymethyl methacrylate beads, acrylic-styrene copolymer beads, polyethylene, polypropylenemelamine beads, polycarbonate beads, styrene beads, crosslinked polystyrene beads, polyvinyl chloride beads, and benzoguanamine-melamine Formaldehyde beads. Examples of the inorganic fine particles include TiO ₂ , SiO ₂ , ZrO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, talc, mica, silicon rubber, SnO ₂ and Sb ₂ O ₃ . The first particles 143a constituting the first particle scattering layer 143 occupy 0.01 wt% to 50 wt% of the weight ratio of the first particle scattering layer 143. The first average particle size, which is the size of the first particles 143a, may range from 0.5 μm to 25 μm, and the first particle 143a may have an average particle size of 1 μm to 10 μm.

Accordingly, the first particles 143a may have a single average particle diameter having the same size alternatively selected within 0.5 μm to 25 μm. That is, only one particle having the average particle size may be implemented as the first particles 143a of the first particle scattering layer 143 by selecting one of the average particle sizes among the average particle diameters within 0.5 μm to 25 μm. For example, the first particles 143a included in the first particle scattering layer 143 may be implemented as particles having the same average particle diameter of 4 μm.

In addition, the first particles 143a may be implemented as particles having various average particle diameters, and among the average particle diameters within 0.5 μm to 25 μm, particles having various average particle diameters having different sizes are first particles of the first particle scattering layer 143. 143a. For example, 50% of the first particles 143a included in the first particle scattering layer 143 may be implemented at 4 μm, 30% at 6 μm, and 20% at 7 μm.

The critical significance of determining the first average particle size of the first particles 143a in the range of 0.5 μm to 25 μm has a problem of poor shielding when less than 0.5 μm and a decrease in coating property and brightness when larger than 25 μm. This is because there is a problem.

In general, in the case of a liquid crystal display device using a plurality of point light sources (for example, LEDs), there is no light source between the point light source and the point light source, so that a shadow difference occurs in comparison with the point light source. This is the same as when the arrangement of the point light source is visually recognized. The present embodiment eliminates the shadow difference through the diffusion of the light and makes the placement of the point light source unrecognizable. Therefore, the above-described shielding means not to shield light, but to mean that the shadow of the point light source is shielded by removing a difference in shadow generated by using a plurality of point light sources. Such shielding is a matter that can be obtained even in a liquid crystal display using a light guide plate.

Meanwhile, the refractive index of the first particles 143a may be implemented to have a refractive index of 1.4 to 1.8. In order to improve the light diffusion efficiency, the refractive index of the first particles 143a may be greater than that of the translucent resin 143b.

In addition, the shape of the first particles 143a may be a core shell shape, a hollow particle or flake shape, a biconvex shape, a flake shape, or a hemisphere, as shown in FIG. 5. It may have at least one of the shape (mushroom), concave (∪) shape. The core shell shape has a core and a shell structure surrounding the core, and may be implemented as a core that is organic particles and a shell that is inorganic particles, or a core that is inorganic particles and a shell that is organic particles. In addition, the biconvex shape is a convex lens shape on both sides, for example, refers to a rice grain shape lens shape, and in particular, the curvature of the lens shapes on both sides may be formed differently. In addition, the flake (flake) shape is a shape having a lump shape and an irregular face, it refers to a shape having an irregular face, such as a piece separated from the mother. In addition, the hemisphere shape refers to a hemispherical lens shape in which only one surface is convex. In addition, the mushroom (mushroom) refers to the shape of the radius of one end is larger than the radius of the other end, such as mushroom shape, the concave shape refers to the shape having a groove in one side.

In addition, the hollow (hollow fine particles or flake) shape, as the organic or inorganic circular sphere refers to a hollow shape, may include a hollow shape of various forms. For example, the hollow shape may be formed into a spherical shape or a flake shape. In addition, the hollow shape may be formed in a single hollow shape having one air layer, a multi-hole shape having several air layers, and the like. The air layer formed in the hollow shape may bring a variety of effects, it is possible to obtain the effect of the scattering effect by the air layer, the shielding improvement by the scattering effect and the brightness improvement.

(3) pattern layer

The pattern layer 144 is disposed on a surface opposite to a surface where the base layer 142 and the first particle scattering layer 143 contact each other, that is, on an outer surface of the first particle scattering layer 143 and includes a pattern. The pattern layer 144 is formed with at least one of various patterns, such as a prism having a pitch of 5 μm to 200 μm, a lens, a triangular pyramid, a circular pyramid, a polygonal pyramid, and a lenticular type. The light diffused by the second particle scattering layer 141 and the first particle scattering layer 143 passes vertically with respect to the plane of the liquid crystal display panel while passing through the pattern layer 144 of the diffusion sheet 140 and is uniform. It has a luminance distribution. To this end, the refractive index of the pattern layer 144 may have a refractive index equal to or greater than that of the light transmissive resin 143b of the base layer 142. The light transmittance of the base layer 142 and the first particle scattering layer 143 as shown in FIG. 4 only when the refractive index of the pattern layer 144 is equal to or larger than that of the light transmissive resin 143b of the base layer 142. The light refracted through the resin 143b may be refracted by the pattern layer 144 so as to proceed perpendicular to the plane of the liquid crystal display panel. The refractive index of the pattern layer 144 may have a range of 1.3 to 1.8. In this case, the refractive index of the pattern layer 144 should be designed to have a refractive index equal to or greater than that of the transparent resin 143b. Therefore, when the refractive index of the light-transmissive resin 143b of the base layer 142 has a range of 1.3 to 1.75, the most preferable refractive index of the pattern layer 144 is implemented to have a refractive index of 1.3 to 1.8, which is the same or larger range. It is preferable to.

For reference, the pattern layer 144 may be formed of a pattern layer 144 having various optical shapes such as a prism having a pitch of 5 μm to 200 μm, a lens, a triangular pyramid, a circular pyramid, a polygonal pyramid, a lenticular shape, and the like. . The pattern layer 144 may be formed using an ultraviolet curable resin having an acrylate or epoxy as a reactive functional group. For example, a patterned mold may be filled with an ultraviolet curable resin. After filling the surface of the curable resin filled with the outer surface of the first particle scattering layer 143 and irradiated with ultraviolet light to cure the ultraviolet curable resin. When the ultraviolet curable resin is cured, the mold may be removed to form a patterned ultraviolet curable resin on the outer surface of the first particle scattering layer 143.

(4) second particle scattering layer

The second particle scattering layer 141 is formed on the other surface of the base layer 142 and is formed of a coating layer of the plurality of second particles 141a. The second particle coating layer may be implemented in a form in which a coating of a second particle layer of a single layer or a second particle layer of a multilayer is coated. The second particle scattering layer 141 is a layer formed using an ultraviolet curable coating resin or a thermosetting coating resin having a nonvolatile component of 5% to 100% in the total weight ratio. The coating layer of the second particle scattering layer 141 may be formed by incorporating the second particles 141a into a UV curable resin or an epoxy resin in a liquid state, and curing them by applying ultraviolet rays or by applying heat. In addition, various coating layer forming methods such as a coating layer using a roller may be applied.

The type of the second particles 141a which are the scattering particles constituting the second particle scattering layer 141 is not limited, and may be organic fine particles or inorganic fine particles. Examples of the organic fine particles include polymethyl methacrylate beads, acrylic-styrene copolymer beads, melamine beads, polycarbonate beads, styrene beads, crosslinked polystyrene beads, polyvinyl chloride beads, and benzoguanamine-melamine formaldehyde beads. Include. Examples of the inorganic fine particles include SiO ₂ , ZrO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO _2, and Sb ₂ O ₃ . The second particles 141a constituting the second particle scattering layer 141 occupy 0.01 wt% to 50 wt% of the weight ratio of the second particle scattering layer 141. The second average particle size, which is the size of the second particles 141a, may be in the range of 1 nm to 500 μm, preferably 5 μm. In addition, the shape of the second particles 141a may be a core shell shape, a hollow particle or flake shape, a biconvex shape, a flake shape, or a hemisphere, as shown in FIG. 5. ), Mushroom (mushroom), concave (∪) shape may have any one shape.

Meanwhile, as described above, the second particle scattering layer 141, the base layer 142, the first particle scattering layer 143, and the pattern layer 144 are formed on one diffusion sheet 140 to improve light diffusion efficiency. In order to improve the luminance distribution, look at the parameter characteristics between the layers.

Examples of shapes and structures are as follows.

Shape of first particle 143a: core shell shape, hollow particulate or flake shape, biconvex shape, flake shape, hemisphere shape, mushroom It may have at least any one of a shape and a concave shape.

Shape of second particle 141a: core shell shape, hollow particulate or flake shape, biconvex shape, flake shape, hemisphere shape, mushroom Although it has at least one shape among a shape and a concave shape, it has a shape different from 1st particle | grains 143a especially.

The first particle 143a and the second particle 141a may have a core shell shape, a hollow particle or flake shape, a biconvex shape, a flake shape, a hemisphere shape, It has at least one of a mushroom shape and a concave shape, respectively, wherein the shape of the selected first particles 143a and the shape of the second particles 141a are different from each other. . For example, when the first particles 143a have a co-shell shape, the second particles 141a may have a shape other than the core shell shape, that is, hollow particles or flake shape, biconvex shape, It is implemented to have any one of the flake shape. As such, by varying the shapes between the first particles 143a and the second particles 141a, the scattering effect can be improved by changing the refractive direction and the refractive index. Combinations of the shapes of the first particles 143a and the second particles 141a may appear in various ways, and FIG. 6 shows the shape combinations of these particles and their experimental results. Referring to FIG. 6, when only a single sheet is implemented without using the first particles and the second particles as in Comparative Example 1, the luminance property is 100%, but the coating property is not improved. Also, as in Comparative Example 2 and Comparative Example 3, when the shape of the first particle 143a and the second particle 141a have the same shape, it can be seen that the luminance characteristic is 80% which is much smaller than the reference value of 100%. have. However, when the first particles 143a and the second particles 141a have different shapes as in the first to fourth embodiments, the luminance characteristics are close to 100%, which is a reference value, and the coating property is improved. have. In particular, when the first particle 143a has a hollow particle or flake shape and the second particle 141a has a core shell shape, as in the third embodiment, shielding force, coating property, and brightness It can be seen that the properties are the most improved, in particular the luminance properties are up to 101%, and the shielding and coating properties are the best.

Examples of refractive indices are as follows.

-Refractive index of the pattern layer 144: 1.3 to 1.8

-Refractive index of the transmissive resin 143b of the first particle scattering layer 143: 1.3 to 1.75

Refractive index of the first particles 143a of the first particle scattering layer 143: 1.4 to 1.8

The refractive index of the pattern layer 144 is formed to be equal to or larger than the refractive index of the transparent resin 143b. When the refractive index of the pattern layer 144 is equal to or larger than the refractive index of the light transmissive resin 143b, the light passes through the light transmissive resin 143b of the base layer 142 and the first particle scattering layer 143 as shown in FIG. 4. The refracted light may be refracted by the pattern layer 144 so that the refracted light travels perpendicular to the plane of the liquid crystal display panel. In addition, the refractive index of the first particles 143a is larger than the refractive index of the translucent resin 143b. The refractive index of the first particles 143a must be greater than the refractive index of the translucent resin 143b so that the light incident on the first particles 143a can be provided to the pattern layer 144 without leaking to the edges of the pattern layer 144. Can be.

An example of the average particle size is as follows.

First average particle size of the first particles 143a: monodispersion comprising any of 0.5 μm to 25 μm, or polydispersion including various sizes of 0.5 μm to 25 μm, preferably 1 μm ~ 10㎛

Second average particle size of second particle 141a: 1 nm to 500 μm, most preferably 5 μm ± 0.5 μm

The first average particle size, which is the size of the first particles 143a, has a size in the range of 0.5 µm to 25 µm, preferably 1 µm to 10 µm. The first particles 143a may have a single average particle diameter formed in the same size alternatively within 0.5 μm to 25 μm. That is, one of the average particle diameters within the range of 0.5 μm to 25 μm may be selected to implement a monodisperse structure having only the particles having the average particle size as the first particles 143a of the first particle scattering layer 143. Can be. For example, the first particles 143a included in the first particle scattering layer 143 may be implemented as particles having the same average particle diameter of 4 μm. In addition, the first particles 143a may be implemented in a polydispersion structure including particles of various average particle diameters having different sizes, and among the average particle diameters within 0.5 μm to 25 μm, the first particle scattering layer 143 It may be implemented as a first particle (143a) of. For example, 50% of the first particles 143a included in the first particle scattering layer 143 may be implemented at 4 μm, 30% at 6 μm, and 20% at 7 μm.

The first average particle diameter, which is the average particle diameter of the first particles 143a, and the second average particle size, which is the average particle diameter of the second particles 141a, may be different from each other. Therefore, the second average particle diameter, which is the size of the second particles 141a, includes a size between 1 nm and 500 μm, and most preferably, includes a size of 5 μm. As such, if the second average particle diameter includes a size of 5 µm, the first particles 143a may be determined as sizes between 1 µm and 4.99 µm and 5.01 µm and 10 µm to have a size different from that of the second average particle diameter. do.

7 and 8 show the experimental results according to the combination of the shape and particle size of these particles. As described in Examples 5 to 8, 13 and 14, it can be seen that the luminance characteristics are deteriorated when the first and second particles have the same shape. On the contrary, as described in Examples 9 to 12, 15, 16, and 17 to 20, it can be seen that the luminance characteristics are improved when the first and second particle shapes are different from each other. In particular, as described in Examples 9 and 17, It can be seen that the luminance characteristic is most improved when the sizes of the first and second particles differ.

Although the invention has been described with reference to the accompanying drawings and the preferred embodiments described above, the invention is not limited thereto, but is defined by the claims that follow. Accordingly, one of ordinary skill in the art may variously modify and modify the present invention without departing from the spirit of the following claims.

Claims

A base layer transmitting light;

A first particle scattering layer formed on one surface of the base layer and including a translucent resin containing a plurality of first particles;

A pattern layer including a pattern formed on the first particle scattering layer; And

And a second particle scattering layer formed on the other surface of the base layer, the second particle scattering layer including a coating layer containing a plurality of second particles having a shape different from that of the first particles.
The method according to claim 1,

The refractive index of the first particle is larger than the refractive index of the translucent resin.
The diffusion sheet of claim 2, wherein the light transmissive resin has a refractive index in a range of 1.3 to 1.75, and a refractive index of the first particles in the first particle scattering layer is in a range of 1.4 to 1.8.
The diffusion sheet of claim 1, wherein the refractive index of the pattern layer is equal to or larger than that of the light-transmissive resin.
The diffusion sheet of claim 4, wherein the refractive index of the pattern layer has a range of 1.3 to 1.8, and the refractive index of the light transmissive resin has a range of 1.3 to 1.75.
The diffusion sheet of claim 1, wherein an average particle diameter of the first particles and the second particles is different from each other.
The diffusion sheet of claim 6, wherein the plurality of first particles are formed to have the same size selected within 0.5 μm to 25 μm, or different sizes within 0.5 μm to 25 μm.
The diffusion sheet of claim 6, wherein the average particle diameter of the second particles is in a range of 1 nm to 500 μm.
The method according to claim 1, wherein the first particle comprises at least one of a core shell shape, hollow shape, biconvex shape, flake shape,

The second particle is a diffusion sheet, characterized in that it comprises at least one shape different from the first particle among the core shell shape, hollow shape, biconvex shape, flake shape.
The diffusion sheet of claim 1, wherein when the first particles have a hollow shape, the second particles have a core shell shape.
The diffusion sheet of claim 1, wherein the pattern of the pattern layer has at least one of a prism, a lens, a triangular pyramid, a circular pyramid, a polygonal pyramid, and a lenticular type having a pitch of 5 μm to 200 μm.
A display unit for displaying an image;

A lamp unit for generating light; And

And a single diffusion sheet for diffusing the light toward the display unit.

The diffusion sheet,

A base layer transmitting light;

A first particle scattering layer formed on one surface of the base layer and including a translucent resin containing a plurality of first particles;

A pattern layer including a pattern formed on the first particle scattering layer; And

And a second particle scattering layer formed on the other surface of the base layer and including a plurality of second particles having a shape different from that of the first particles.
The display device of claim 12, wherein the refractive index of the pattern layer is equal to or larger than that of the light transmissive resin, and the refractive index of the first particles is greater than that of the light transmissive resin.
The method according to claim 13, wherein the refractive index of the pattern layer has a range of 1.3 ~ 1.8, the refractive index of the translucent resin has a range of 1.3 ~ 1.75, the refractive index of the first particles of the first particle scattering layer is 1.4 ~ 1.8 Display device with range.
The display device of claim 12, wherein the first average particle diameter, which is the average particle diameter of the first particles, and the second average particle size, which is the average particle diameter of the second particles, are different from each other.
The display device of claim 12, wherein the first average particle diameter of the first particles has an alternative single size within 0.5 μm to 25 μm, or different sizes within 0.5 μm to 25 μm.
The method of claim 12, wherein the first particle comprises at least one of a core shell shape, a hollow shape, a biconvex shape, a flake shape,

And the second particle includes at least one of a core shell shape, a hollow shape, a biconvex shape, and a flake shape, and has a shape different from that of the first particle.