KR102214924B1 - diffuser sheet and display unit - Google Patents

Abstract

The present invention relates to a diffusion sheet and a display device to which the same is applied, and a diffusion sheet to improve luminance by diffusing light emitted from a light source, and a display device to which the same is applied. An embodiment of the present invention is a base layer that transmits light; A first particle scattering layer formed on one surface of the base layer and comprising a light-transmitting 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 coating layer including a plurality of second particles having a shape different from that of the first particle.

Description

Diffuser sheet and display device to which it is applied {diffuser sheet and display unit}

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

Unlike other display devices, a liquid crystal display device is not a light-emitting material in which the liquid crystal material injected between the TFT substrate and the color filter emits light itself, but is a light-receiving material that adjusts the amount of light coming from the outside and displays it on the screen. A separate device for irradiating light, that is, a backlight assembly is required.

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

The liquid crystal display 1 includes a backlight assembly 10 for generating light, and a display unit 20 provided above 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. Further, the liquid crystal display panel 25 includes a TFT substrate 22 and a color filter substrate 23 on which electrodes are formed, and a liquid crystal layer (not shown) injected between the TFT substrates and the color filter substrates 22 and 23.

The backlight assembly 10 includes a mold frame (not shown) in which a storage space is formed, a reflective sheet 12 installed on the base surface of the storage space to reflect light toward a liquid crystal display panel, and an upper surface of the reflection sheet to guide light. Light guide plate 13, a lamp unit 11 installed between the light guide plate 13 and the sidewall of the storage space to emit light, and optical sheets 17 stacked on the upper surface of the light guide plate 13 to diffuse and condense light ), a top chassis (not shown) installed on the top of the mold frame and covering an area from a predetermined position at the edge of the liquid crystal display panel to the side surface of the mold frame.

Here, the optical sheets 17 include a diffusion sheet 14 for diffusing light, and a prism sheet 15 stacked on the upper surface of the diffusion sheet 14 to condense the diffused light and transmit it 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, it has a composite sheet structure in which two or three optical sheets 17 applied to a BLU (Back Light Unit) are laminated to form a single sheet. Such composite sheets are in the spotlight in the market due to their effects such as thinning, shielding power, high luminance realization, and reduction in the number of processes provided.

However, the optical sheets 17 made of such a composite sheet are manufactured by using two or three fabrics in the manufacturing process, so that the product unit price by the cost of the fabric is high, and the process of joining multiple sheets is essential. There is a problem that causes many defects in the process.

Korean Patent Publication 10-2010-0057483

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

An embodiment of the present invention is a base layer that transmits light; A first particle scattering layer formed on one surface of the base layer and comprising a light-transmitting 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 coating layer including a plurality of second particles having a shape different from that of the first particle.

The refractive index of the first particle is characterized in that it is greater than the refractive index of the light-transmitting resin.

The refractive index of the light-transmitting resin has a range of 1.3 to 1.75.

The refractive index of the pattern layer is the same as or greater than the refractive index of the light-transmitting resin.

The refractive index of the pattern layer is in the range of 1.3 to 1.8, and the refractive index of the translucent resin is in the range of 1.3 to 1.75.

The average particle diameters of the first particles and the second particles are different from each other.

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

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

The first particle has a shape of any one of a core-shell shape, a hollow shape, a biconvex shape, and a flake shape, and the second particle is a core-shell shape, a hollow shape, a biconvex shape, and a flake shape. It includes those having any other shape.

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

An embodiment of the present invention is a display unit that displays an image; A lamp unit that generates light; A light guide plate guiding the light generated by the lamp unit; And a single diffusion sheet for diffusing the light guided by the light guide plate to the display unit. Including, the diffusion sheet, the base layer for transmitting light; A first particle scattering layer formed on one surface of the base layer and comprising a light-transmitting 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 particle.

The refractive index of the pattern layer is equal to or greater than the refractive index of the light-transmitting resin, and the refractive index of the first particles is formed to be greater than the refractive index of the light-transmitting resin.

The refractive index of the pattern layer has a range of 1.3 to 1.8, and the refractive index of the light-transmitting resin has a range of 1.3 to 1.75.

The first average particle diameter, which is the average particle diameter of the first particles, and the second average particle diameter, which is the average particle diameter of the second particles are different from each other.

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

The first particle has a shape of any one of a core-shell shape, a hollow shape, a biconvex shape, and a flake shape, and the second particle is a core-shell shape, a hollow shape, a biconvex shape, and a flake shape. It includes those having any other shape.

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

1 is a cross-sectional view showing the configuration of a conventional liquid crystal display device.
2 is a cross-sectional view showing a configuration of a display device according to an exemplary embodiment of the present invention.
3 is a cross-sectional view of a diffusion sheet according to an embodiment of the present invention.
4 is a view showing a state of refracting light in a diffusion sheet according to an exemplary embodiment of the present invention.
5 is a cross-sectional view of various particles according to an embodiment of the present invention.
6 is a table showing brightness, shielding power, and coating properties according to a combination of shapes of first and second particles according to an embodiment of the present invention.
7 and 8 are tables showing luminance, shielding power, and coating properties according to a combination of shapes and sizes of first particles and second particles according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, only the present embodiments make the disclosure of the present invention complete, and the scope of the invention to those of ordinary skill in the art It is provided to inform you. In the drawings, the same reference numerals refer to the same elements.

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

Hereinafter, a liquid crystal display will be exemplified as an example of a display device, and the backlight assembly will be described with an edge type light source as an example, but may be applied to a vertical light source as well.

Referring to FIG. 2, in a liquid crystal display, a backlight assembly 100 for generating light and a display unit 200 that is provided on an upper side of 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 that generates 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. In addition, the liquid crystal display panel 250 includes a TFT substrate with electrodes and color filter substrates 220 and 230, and a liquid crystal layer (not shown) injected between the TFT substrate and the color filter substrates 220 and 230.

The lamp unit 110 includes a lamp 110a generating light and a lamp reflector 110b surrounding the lamp 110a. In addition, the light generated from the lamp 110a is incident on the light guide plate 130, which will be described later, and the lamp reflector 110b reflects the light generated from the lamp 110a to the light guide plate 130, so that it is incident on the light guide plate 130. It plays a role of increasing the amount of light that is generated. And, the light guide unit includes a reflector 120, a light guide plate 130, and a diffusion sheet 140, and the light guide plate 130 is provided on one side of the lamp unit 110 to guide light from the lamp unit 110. Play a role. Further, a reflective plate 120 for reflecting light leaked from the light guide plate 130 back to the light guide plate 130 is provided under the light guide plate 130.

Meanwhile, a diffusion sheet 140 for improving the efficiency of light guided by the light guide plate 130 is provided on the light guide plate 130. The diffusion sheet 140 scatters light incident from the light guide plate 130 to evenly distribute the luminance 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. Done. That is, the base layer 142 and the first particle scattering layer 143 made of the first particles 143a in the same translucent resin 143b as the base layer 142 and formed on one surface of the base layer 142 , The pattern layer 144 having a pattern formed on the outer surface of the first particle scattering layer 143 facing the surface in contact with the base layer 142, and a plurality of second particles formed on the other surface of the base layer 142 It includes a second particle scattering layer 141 made of the coating layer of (141a).

The light diffused by the second particle scattering layer 141 and the first particle scattering layer 143 is condensed in a direction perpendicular to the plane of the liquid crystal display panel, and accordingly, the pattern layer 144 of the diffusion sheet 140 Most of the light passing through the liquid crystal panel proceeds vertically with respect to the plane of the liquid crystal display panel to have a uniform luminance distribution. Hereinafter, a diffusion sheet 140 according to an 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-transmitting substrate. Translucent resins such as PET (PolyEthylene Terephthalate), PMMA (PolyMethyMethAcrylate) PEN (PolyEthylene Naphthalate), PP (PolyPropylene), PC (PolyCarbonate), TAC (TriAetyl Cellulose) resin may be used, but are not limited thereto. .

(2) first particle scattering layer

The first particle scattering layer 143 includes a light-transmitting resin 143b and first particles 143a, which are scattering particles for controlling a refractive index. The first particle scattering layer 143 is a layer formed using an ultraviolet-curable coating resin in which non-volatile components constitute 5 to 100% of the total weight ratio, and the shape of the first particles 143a is the second particle scattering layer ( The shape is different from that of the second particle 141a of 141).

Hereinafter, the light-transmitting resin 143b and the first particles 143a as scattering particles will be described in detail.

-Translucent resin-

As the light-transmitting resin 143b, which is a material of the light-transmitting resin 143b, a resin cured by any one of ultraviolet rays, electron beams, and heat is mainly used. More specifically, there are three types of resins, that is, photocurable resins, ionizing radiation curable resins, and thermosetting resins, and PET, PEN, PP, PC, TAC, and the like may be used, but are not limited thereto. Further, for these curable resins, a mixture of a thermoplastic resin and a solvent is used.

The light-transmitting 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 crosslinked. The polymer having a saturated hydrocarbon as the main chain is preferably obtained by 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 a material.

Examples of monomers having two or more ethylenically unsaturated groups include esters of polyhydric alcohols and (meth)acrylic acid (e.g., ethylene glycol di(meth)acrylate, 1,4-diclohexane diacrylate, pentaerythritol tetra( Meth)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), vinylsulfone (eg, divinylsulfone), acrylamide (eg, methylene Bisacrylamide), 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 particularly preferred.

A monomer having an ethylenically unsaturated group can be dissolved in a solvent together with various polymerization initiators and other additives, coated and dried, and then subjected to polymerization reaction under ultraviolet rays, ionizing radiation or heating, thereby curing the coating.

In place of or in addition to polymerization of a monomer having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the matrix by reaction of a crosslinkable group. 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. In addition, vinylsulfonic acid, acid anhydride, cyanoacrylate derivatives, melamine, etherified methylol, ester, or metal alkoxides such as urethane and tetramethoxysilane may be used as a monomer for introducing a crosslinked structure. Further, a functional group exhibiting crosslinkability as a result of the decomposition reaction may be used, such as a blocked isocyanate group. That is, the crosslinkable functional group used in the present invention is not limited to a functional group causing an immediate reaction, and may be a group exhibiting reactivity after decomposition. A crosslinked structure can be formed by coating and then heating a 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 monomers 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 phenetol; 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 Lolactone; And an organic solvent having two or more 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 the solvent 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 of them may be used in combination.

A material for forming the translucent resin 143b is coated on the base layer 142 by a bar coater or a spin coater.

As a method of curing the ionizing radiation curable resin composition, a conventional curing method for the ionizing radiation curable resin composition, that is, curing by irradiation with an electron beam or ultraviolet rays may 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, insulated core transformer type, straight type, dynamitron type and high frequency type An electron beam having an energy of 50 to 1,000 KeV, preferably 100 to 300 KeV, emitted from the accelerator may be used, and in the case of ultraviolet curing, an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, carbon arc, xenon arc, metal halide lamp It is also possible to use ultraviolet rays emitted from light rays such as the back.

It is preferable to implement the light-transmitting resin (143b) to have a refractive index of 1.3 to 1.75. In order to improve diffusion efficiency, the refractive index of the light-transmitting resin 143b should be smaller than that of the pattern layer 144 and should be smaller than the refractive index of the first particles 143a.

-First particle-

The type of the first particles 143a, which are 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, polypropylene melamine beads, polycarbonate beads, styrene beads, crosslinked polystyrene beads, polyvinyl chloride beads, and benzoguanamine-melamine It contains formaldehyde beads. Examples of 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 forming the first particle scattering layer 143 occupy 0.01% to 50% of the weight ratio of the first particle scattering layer 143. The first average particle diameter, which is the size of the first particles 143a, may have a size of 0.5 μm to 25 μm, preferably 1 μm to 10 μm.

Accordingly, the first particles 143a may have a single average particle diameter of the same size selected within 0.5 μm to 25 μm. That is, by selecting any one of the average particle diameters from 0.5 μm to 25 μm, only particles having the corresponding average particle diameter may be implemented as the first particles 143a of the first particle scattering layer 143. 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 of various average particle diameters. Among the average particle diameters within 0.5 μm to 25 μm, particles of various average particle diameters having different sizes are used as the first particles of the first particle scattering layer 143. It can be implemented with (143a). For example, of the first particles 143a included in the first particle scattering layer 143, 50% may be implemented as 4 μm, 30% may be implemented as 6 μm, and 20% may be implemented as 7 μm.

The critical significance of determining the first average particle diameter of the first particles (143a) to a size of 0.5 μm to 25 μm is that if it is less than 0.5 μm, there is a problem in that the shielding property is inferior, and if it is larger than 25 μm, the coatability and brightness are decreased. 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 (LEDs), since there is no light source between the point light source and the point light source, a difference in shade occurs compared to the upper portion of the point light source. This is the same as the arrangement of the point light source is visually recognized. In this embodiment, the difference in shadows is removed through the diffusion of light and the arrangement of the point light source cannot be recognized. Therefore, the meaning of the above-described shielding property does not block light, but means that the visibility of the point light source is shielded by removing the difference in shades generated by using a plurality of point light sources. This shielding property can be obtained even in a liquid crystal display device using a light guide plate.

Meanwhile, in order to improve the light diffusion efficiency, the refractive index of the first particles 143a is implemented to be greater than that of the light-transmitting resin 143b.

In addition, the shape of the first particle 143a is a core shell shape, a hollow particle or flake shape, a biconvex shape, a flake shape, and a hemisphere shape as shown in FIG. 5. ) Shape, mushroom (mushroom) shape, it may have any one of the concave (∪) shape. In the above, the core shell has a core and a shell structure surrounding the core, and may be implemented as a core as organic fine particles and a shell as inorganic fine particles, or may be implemented as a core as inorganic fine particles and a shell as organic fine particles. In addition, the biconvex shape refers to a lens shape in which both sides are convex, for example, a shape of a lens in the shape of rice grains, and in particular, the curvature of the lens shape on both sides may be formed differently. In addition, the flake shape is a shape having a lump shape and an irregular surface, and refers to a shape having an irregular surface such as a piece separated from the parent body. In addition, a hemisphere shape refers to a hemispherical lens shape in which only one surface is convex. In addition, the shape of a mushroom refers to a shape in which the radius of one end is larger than the radius of the other end, like a mushroom shape, and the concave (∪) shape refers to a shape having a groove in which one side is dug.

In addition, the hollow (hollow particulate or flake) shape refers to a shape in which the center is hollow as an organic or inorganic circular sphere, and may include various types of hollow shapes. For example, the hollow shape may be formed in a spherical shape or a flake shape. In addition, the hollow shape may be formed in a single hollow shape with one air layer, a multi-hole shape with several air layers, or the like. The air layer formed in the hollow shape can bring various effects, and the scattering effect due to the air layer, shielding improvement due to the scattering effect, and luminance enhancement can be obtained.

(3) Pattern layer

The pattern layer 144 has a pattern formed on the outer surface of the first particle scattering layer 143 facing the surface in contact with the base layer 142. The pattern layer 144 has various types of 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 an lenticular type shape. The light diffused by the second particle scattering layer 141 and the first particle scattering layer 143 passes through the pattern layer 144 of the diffusion sheet 140 and proceeds perpendicular to the plane of the liquid crystal display panel. Have a luminance distribution. To this end, the refractive index of the pattern layer 144 is equal to or greater than the refractive index of the light-transmitting resin 143b of the base layer 142. When the refractive index of the pattern layer 144 is equal to or greater than the refractive index of the light-transmitting resin 143b of the base layer 142, the transmittance of the base layer 142 and the first particle scattering layer 143 as shown in FIG. 4 This is to refract in the pattern layer 144 so that the light refracted through the resin 143b proceeds perpendicular to the plane of the liquid crystal display panel. The refractive index of the pattern layer 144 may range from 1.3 to 1.8. At this time, the refractive index of the pattern layer 144 should be designed to have a refractive index greater than or greater than that of the translucent resin 143b. Therefore, when the refractive index of the translucent resin 143b of the base layer 142 is in the 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 desirable to do it.

For reference, the pattern layer 144 may be formed of a pattern layer 144 having various optical shapes such as a prism, lens, triangular pyramid, circular pyramid, polygonal pyramid, lenticular type shape, etc. having a pitch of 5 μm to 200 μm. . The pattern layer 144 may be formed by using an ultraviolet curable resin having acrylate or epoxy as a reactive functional group. For example, the surface of the cured resin filled after the ultraviolet curable resin is filled in a pattern-shaped mold After being added to the outer surface of the first particle scattering layer 143, ultraviolet rays are irradiated to cure the ultraviolet curable resin. When the UV-curable resin is cured, the mold is removed, so that the pattern-shaped UV-curable resin may be formed 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 made of a coating layer of a plurality of second particles 141a. This second particle coating layer may be implemented in a form in which a single second particle layer or a multilayer second particle layer is coated. The second particle scattering layer 141 is a layer formed using a UV-curable coating resin or a thermosetting coating resin in which non-volatile components constitute 5% to 100% by weight of the total weight. A coating layer of the second particle scattering layer 141 may be formed by containing the second particles 141a in a liquid UV curable resin or epoxy resin, curing by irradiating ultraviolet rays or curing 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 scattering particles constituting the second particle scattering layer 141, is not limited, and may be organic fine particles or inorganic fine particles. Examples of 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% to 50% of the weight ratio of the second particle scattering layer 141. The second average particle diameter, which is the size of the second particles 141a, has a size between 1 nm and 500 µm, and preferably has a size of 5 µm. In addition, the shape of the second particle 141a is a core shell shape, a hollow particle or flake shape, a biconvex shape, a flake shape, and a hemisphere shape as shown in FIG. 5. ) Shape, mushroom (mushroom) shape, it may have any one of the concave (∪) 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. By doing so, the luminance distribution is improved, and the parameter characteristics between each layer are examined.

<Shape structure between the first particle and the second particle>

Examples of preferred shape structures are as follows.

-Shape of the first particle (143a): core shell shape, hollow (hollow particulate or flake) shape, biconvex shape, flake shape, hemisphere shape, mushroom (mushroom) It may have any one of a shape and a concave (∪) shape.

-Shape of the second particle 141a: core shell shape, hollow particle or flake shape, biconvex shape, flake shape, hemisphere shape, mushroom It has a shape of any one of a shape and a concave (∪) shape, in particular, to have a shape different from that of the first particle (143a).

The first particle (143a) and the second particle (141a) are a core shell shape, a hollow particle or flake shape, a biconvex shape, a flake shape, a hemisphere shape, Each has a shape of a mushroom (mushroom) shape and a concave (∪) shape, and at this time, the shape of the selected first particle (143a) and the shape of the second particle (141a) are different from each other. For example, when the first particle 143a has a coarse shell shape, the second particle 141a has a shape other than a core shell shape, that is, a hollow particle or flake shape, a biconvex shape, It is implemented to have any one shape among flake shapes. By making the shapes between the first particles 143a and the second particles 141a different from each other, the refraction direction and the refractive index are different to improve the scattering effect. Combinations of the shapes of the first particles 143a and the second particles 141a may appear in various ways, and FIG. 6 shows the combination of shapes of these particles and the experimental results. Referring to FIG. 6, it can be seen that, as in Comparative Example 1, when only a single sheet is implemented without the first and second particles, the luminance characteristic is 100%, but the coating property is not improved. In addition, 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 has a much smaller 80% range than the reference value of 100%. have. However, as in Examples 1 to 4, when the shapes of the first particles 143a and the second particles 141a have different shapes, it can be seen that the luminance characteristic approaches 100%, which is the reference value, and the coating property is improved. . In particular, as in Example 3, when the first particle (143a) has a hollow (hollow particulate or flake) shape, and the second particle (141a) has a core shell shape, shielding power and coating properties, brightness It can be seen that the characteristics are the most improved, and in particular, the luminance characteristics are shown up to 101%, and the shielding power and coating properties are the best.

<refractive index>

Examples of preferred refractive index are as follows.

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

-The refractive index of the light-transmitting resin (143b) of the first particle scattering layer (143): 1.3-1.75

The refractive index of the pattern layer 144 is equal to or greater than the refractive index of the translucent resin 143b. When the refractive index of the pattern layer 144 is equal to or greater than the refractive index of the light-transmitting resin 143b, it passes through the light-transmitting resin 143b of the base layer 142 and the first particle scattering layer 143 as shown in FIG. Accordingly, the refracted light may be refracted in the pattern layer 144 so that it proceeds perpendicular to the plane of the liquid crystal display panel. In addition, the refractive index of the first particles 143a is formed to be greater than that of the translucent resin 143b. When the refractive index of the first particles 143a is greater than the refractive index of the translucent resin 143b, the light incident on the first particles 143a can be provided to the pattern layer 144 without leaking the edge of the pattern layer 144. I can.

<The average particle size of the first and second particles>

Examples of preferred average particle diameter sizes are as follows.

-The first average particle size size of the first particles (143a): monodisperse including any one of 0.5 μm to 25 μm, or polydisperse including various sizes of 0.5 μm to 25 μm, preferably 1 μm ~10㎛

-The second average particle size of the second particles (141a): 1nm ~ 500㎛, most preferably 5㎛ ± 0.5㎛

The first average particle size, which is the size of the first particles 143a, has a size within 0.5 μm to 25 μm, and preferably 1 μm to 10 μm. The first particles 143a may have a single average particle diameter formed in the same size selected within 0.5 μm to 25 μm. In other words, by selecting any one of the average particle diameters within 0.5㎛ to 25㎛, and implementing a monodisperse structure having only particles having the corresponding average particle diameter as the first particles 143a of the first particle scattering layer 143 I can. 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 a polydispersed structure including particles of various average particle diameters of different sizes. Among the average particle diameters within 0.5 μm to 25 μm, particles of various average particle diameters are included in the first particle scattering layer 143 ) Of the first particle (143a). For example, of the first particles 143a included in the first particle scattering layer 143, 50% may be implemented as 4 μm, 30% may be implemented as 6 μm, and 20% may be implemented as 7 μm.

The first average particle diameter, which is the average particle diameter of the first particles 143a, and the second average particle diameter, which is the average particle diameter of the second particles 141a are different from each other. Accordingly, the second average particle diameter, which is the size of the second particles 141a, includes a size between 1 nm and 500 μm, and preferably, it is most preferable to include a size of 5 μm. As described above, if the second average particle diameter includes a size of 5 μm, the first particle 143a is determined to have a size between 1 μm and 4.99 μm and 5.01 μm to 10 μm so as to have a size different from 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, when the first and second particles have the same shape, it can be seen that the luminance characteristics are deteriorated. Conversely, as described in Examples 9 to 12, 15, 16, and 17 to 20, when the shapes of the first and second particles are different from each other, it can be seen that the luminance characteristics are improved, in particular, as described in Examples 9 and 17. It can be seen that when the sizes of the first and second particles are different, the luminance characteristics are most improved.

Although the present invention has been described with reference to the accompanying drawings and the above-described preferred embodiments, the present invention is not limited thereto, but is limited by the claims to be described later. Therefore, those of ordinary skill in the art can variously modify and modify the present invention within the scope of the technical spirit of the claims to be described later.

100: backlight assembly 110: lamp unit
120: reflective plate 130: light guide plate
140: diffusion sheet 141: second particle scattering layer
141a: second particle 142: base layer
143: first particle scattering layer 143a: first particle
143b: light-transmitting resin 144: pattern layer

Claims (17)

A base layer that transmits light;
A first particle scattering layer formed on one surface of the base layer and comprising a light-transmitting 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, including a coating layer containing a plurality of second particles, and into which light is incident;
Including,
The shape between the first particle and the second particle is different from each other so that the scattering effect can be improved by different refracting directions,
The first particle comprises a hollow shape,
Including that the average particle diameter of the first particle and the second particle are different from each other,
The plurality of first particles include those formed in different sizes within 0.5㎛ ~ 25㎛,
The diffusion sheet, characterized in that the particle diameter of the second particle is formed to a size within 1nm ~ 500㎛.
The method according to claim 1,
The refractive index of the first particle is greater than that of the light-transmitting resin,
The diffusion sheet, characterized in that the refractive index of the light-transmitting resin has a range of 1.3 to 1.75.
delete The method according to claim 1, wherein the refractive index of the pattern layer is equal to or greater than the refractive index of the light-transmitting resin,
The refractive index of the pattern layer has a range of 1.3 to 1.8, the refractive index of the light-transmitting resin is a diffusion sheet, characterized in that the range of 1.3 to 1.75.
delete delete delete delete The diffusion sheet according to claim 1, wherein the second particle has a shape of any one of a core-shell shape, a hollow shape, a biconvex shape, and a flake shape.
delete delete delete delete delete delete delete delete

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