KR100813859B1 - Prism sheet and backlight assembly and liquid crystal display comprising the same - Google Patents

Abstract

A prism sheet, a backlight assembly including the same, and a liquid crystal display device are provided. The prism sheet includes a transparent substrate, a prism array in which a plurality of three-dimensional structures are repeatedly formed on the transparent substrate, and a plurality of diffusion beads positioned between the prism arrays.

Liquid Crystal Display, Optical Member, Prism Sheet, Diffusion Bead

Description

Prism sheet, backlight assembly and liquid crystal display including the same {Prism sheet and backlight assembly and liquid crystal display comprising the same}

1 is a perspective view of a prism sheet according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II 'of FIG. 1.

3 is a perspective view of a prism sheet according to another embodiment of the present invention.

4 is a cross-sectional view taken along the line IV-IV 'of FIG. 3.

5 is a perspective view of a prism sheet according to another embodiment of the present invention.

6 is a cross-sectional view taken along the line VI-VI 'of FIG. 5.

7 is a perspective view of a prism sheet according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view taken along the line VII-VII 'of FIG. 7.

9 is a perspective view of a prism sheet according to another embodiment of the present invention.

FIG. 10 is a cross-sectional view taken along the line VII-VII 'of FIG. 9.

11 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

12 is a cross-sectional view of the backlight assembly according to an embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: transparent substrate 20: prism array

100, 110, 120, 130, 140: prism sheet 200: liquid crystal display device

210: backlight assembly

The present invention relates to an optical member, a backlight assembly and a liquid crystal display device including the same, and more particularly, to a prism sheet, a backlight assembly and a liquid crystal display device including the same.

The liquid crystal display is one of flat panel displays that display an image by using the electrical and optical characteristics of a liquid crystal having intermediate characteristics between a liquid and a solid. Liquid crystal display devices are thinner and lighter than other display devices, and have advantages of low driving voltage and low power consumption, and thus are widely used throughout the industry.

The liquid crystal display is a non-light emitting device in which a liquid crystal display panel for displaying an image does not emit light by itself, and thus requires a backlight assembly for supplying additional light.

In general, the backlight assembly includes a light source, a light guide plate for guiding light emitted from the light source, a diffusion sheet disposed on the light guide plate to diffuse light emitted from the light guide plate, and a prism sheet for collecting light emitted from the diffusion sheet. The backlight assembly is provided with a diffusion sheet separately from the prism sheet, thereby increasing the number of parts, thereby making it difficult to reduce the thickness of the backlight assembly, and increase the number of assembly processes and increase the defective rate, thereby increasing the overall production cost. do.

The technical problem to be achieved by the present invention is to provide a prism sheet having a composite function.

Another object of the present invention is to provide a backlight assembly including a prism sheet having a composite function.

Another object of the present invention is to provide a liquid crystal display device including a prism sheet having a composite function.

According to an aspect of the present invention, a prism sheet includes a transparent substrate, a prism array having a plurality of three-dimensional structures repeatedly formed on the transparent substrate, and a plurality of diffusion beads positioned between the prism arrays. do.

The plurality of diffusion beads have substantially the same diameter in the same row.

In this case, the plurality of diffusion beads have different diameters in different rows.

In addition, the plurality of diffusion beads have at least two kinds of diameters in the same row.

In addition, the plurality of diffusion beads as described above includes a plurality of projections on the surface.

These multiple diffusion beads have a diameter of 3-50 μm.

In addition, the plurality of diffusion beads further include a diffusion agent. Such diffusion agents are organic particles or inorganic particles.

The organic particles are at least one selected from acrylic particles, olefin particles, copolymer particles of acrylic and olefin, and multilayer multicomponent particles, and the inorganic particles are selected from silicon oxide, aluminum oxide, titanium oxide, zirconium oxide and magnesium fluoride. At least one is selected.

The prism array is selected from at least one of a linear arrangement of parallel triangular prisms, a square pyramid prism structure, a triangular pyramid prism structure, a hemispherical prism structure and a non-spherical prism structure.

In addition, the prism array and the diffusion beads are integral.

The backlight assembly according to an embodiment of the present invention for achieving the above another technical problem includes a prism sheet as described above.

The liquid crystal display according to the exemplary embodiment of the present invention for achieving the another technical problem includes a prism sheet as described above.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Thus, in some embodiments, well known process steps, well known device structures and well known techniques are not described in detail in order to avoid obscuring the present invention. Like reference numerals refer to like elements throughout.

The spatially relative terms below, beneath, lower, above, upper, etc. may be used to easily describe the correlation of one component with another as shown in the figures. Can be. Spatially relative terms are to be understood as including terms in different directions of the component in use or operation in addition to the directions shown in the figures. For example, when inverting the components shown in the figures, components described as beneath beneath other components may be placed above and above other components. Thus, the exemplary term below may include both the direction below and above. The components can be oriented in other directions as well, so that spatially relative terms can be interpreted according to the orientation.

Hereinafter, a prism sheet according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. 1 is a perspective view of a prism sheet according to an embodiment of the present invention, Figure 2 is a cross-sectional view taken along the line II-II 'of FIG.

The prism sheet 100 according to an embodiment of the present invention has a diffusion function of diffusing light in addition to an original function of increasing brightness by refracting and condensing light.

1 and 2, the prism sheet 100 according to an embodiment of the present invention is a transparent substrate 10, a plurality of prism array (20) and a plurality of diffusion beads (diffusion bead, 30). The transparent substrate 10 and the plurality of prism arrays 20 may be formed separately as shown, but may be formed in one piece. Hereinafter, an example in which the transparent substrate 10 and the plurality of prism arrays 20 are formed separately will be described.

First, the transparent substrate 10 is a plate-like material made of a transparent material that can transmit light, for example, polycarbonate (poly carbonate), poly sulfone (poly sulfone), poly acrylate (poly acrylate), Polystyrene (poly styrene), poly vinyl chloride (poly vinyl chloride), polyvinyl alcohol (poly vinyl alcohol), poly norbornene (poly norbornene) can be made of a polyester (poly ester) series. The transparent substrate 10 may be preferably made of polyethylene terephtalate or polyethylene naphthalate.

The thickness of the transparent substrate 10 may be, for example, 10 to 1000 μm, and preferably 25 to 600 μm. The transparent substrate 10 has excellent mechanical strength and thermal stability in the thickness range as described above, can be provided with appropriate flexibility, and there is little loss of transmitted light.

On the transparent substrate 10, a plurality of three-dimensional prism arrays 20 for refracting and condensing light are arranged in parallel with one side of the transparent substrate 10, for example.

The material constituting the prism array 20 may be a polymer resin including an ultraviolet curable resin or a thermosetting resin. For example, the prism array 20 may use unsaturated fatty acid esters, aromatic vinyl compounds, unsaturated fatty acids and derivatives thereof, vinyl cyanide compounds such as methacrylonitrile, and the like.

The prism array 20 may be made of a material having a higher refractive index than that of the transparent substrate 10, and when the refractive index of the transparent substrate 10 is higher, a part of the light incident on the rear surface of the transparent substrate 10 may be formed in the prism array 20. This is because it may be totally reflected at the surface of) and not be incident to the prism structure.

The prism array 20 has a protruding shape that becomes narrower in width as shown in FIGS. 1 and 2, for example, and may have a prism structure having a triangular cross section. P is a pitch that is a distance between the vertices of the prism array 20, and may be, for example, 40 to 60 μm. H is the height of the prism array 20, and may be, for example, 20 to 30 μm. In addition, θ is an angle formed by the protrusion of the prism array 20, and may be, for example, 80 ° to 100 °. Optical characteristics such as the front luminance and the light intensity distribution in the viewing angle change according to the angle θ formed by the protrusion of the prism array 20. The front luminance and the light intensity distribution are uniform in the θ range as described above.

Also, although not shown, the prism array 20 may be selected from, for example, a square pyramid prism structure, a conical prism structure, a hemispherical prism structure, and a non-spherical prism structure.

A plurality of diffusion beads 30 are positioned between the prism arrays 20 repeatedly arranged on the transparent substrate 10. The diffusion bead 30 may be, for example, spherical, and evenly spreads the light incident on the diffusion bead 30.

The diffusion beads 30 located between the prism arrays 20 have substantially the same diameter over the entire prism sheet 100. The diameter of the diffusion bead 30 may be, for example, 3 to 50 μm, and may be changed to various diameters according to characteristics of the liquid crystal display device to which the prism sheet 100 is applied.

The diffusion beads 30 may be made of, for example, a thermosetting resin such as an acrylic resin, a urethane resin, a polyester resin, and the like, and preferably, an epoxy acrylate resin, a urethane acrylate resin, and a silicone acrylate resin. It may be made of an ultraviolet curable resin such as.

In addition, the diffusion bead 30 may further include a diffusing agent that can increase the light diffusion. That is, a diffusion agent may be included in the diffusion beads 30 or on the surface of the diffusion beads 30. The diffusing agent may use spherical, non-spherical, triangular pyramid, cubic, polygonal particles, for example organic or inorganic particles.

Examples of the organic particles include methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylamide, metyrolacrylamide, glycidyl methacrylate, and ethyl acrylate. Of acrylic particles of isobutyl acrylate, normal butyl acrylate, 2-ethylhexyl acrylate homopolymer or copolymer and olefinic particles such as polyethylene, polystyrene, polypropylene, copolymers of acryl and olefinic copolymer and homopolymer After forming the particles, it is possible to use multi-layered multi-component particles made by superimposing other types of monomer thereon.

As the inorganic particles, for example, silicon oxide, aluminum oxide, titanium oxide, zirconium oxide, magnesium fluoride and the like can be used.

Such organic particles or inorganic particles are merely exemplary, and it is obvious to those skilled in the art that the organic particles or inorganic particles are not limited to these organic particles or inorganic particles, and may be replaced by other known materials as long as the main object of the present invention can be achieved. It is true.

The diffusion beads 30 are fixed between the prism arrays 20 using a transparent resin or the like. Examples of the transparent adhesive resin include acrylic resins, urethane resins, polyester resins, and the like, and the transparent adhesive resin may also include a diffusion agent.

Subsequently, a prism sheet according to another embodiment of the present invention will be described with reference to FIGS. 3 and 4. 3 is a perspective view of a prism sheet according to another embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along line IV-IV ′ of FIG. 3.

3 and 4, the prism sheet 110 according to another embodiment of the present invention is substantially the same as the prism sheet according to the embodiment of the present invention except for the diffusion beads 32a and 32b. Do. Therefore, a description will be given of the difference between the prism sheet (100 of FIGS. 1 and 2) according to an embodiment of the present invention and the prism sheet 110 according to another embodiment of the present invention.

The prism sheet 110 according to another embodiment of the present invention includes a transparent substrate 10, a plurality of prism arrays 20, and a plurality of diffusion beads 32a and 32b.

For example, a plurality of three-dimensional prismatic arrays 20 are repeatedly arranged on the transparent substrate 10 in parallel with one side of the transparent substrate, and a plurality of diffusion beads 32a and 32b are disposed between the prism arrays 20. Is located.

Diffusion beads 32a and 32b which evenly spread incident light have substantially the same diameter in the same row and have different diameters in different rows. At this time, the rows of the diffusion beads 32a having the first diameter and the rows of the diffusion beads 32b having the second diameter may be alternately positioned between the prism arrays 20 and the diffusion beads 32a having the first diameter Rows of diffusion beads 32b having a second diameter and rows of diffusion beads (not shown) having a third diameter may be alternately located between the prism arrays 20. That is, diffusion bead rows having an nth diameter in the first diameter may be alternately positioned between the prism arrays 20.

The diameters of the diffusion beads 32a and 32b may be, for example, 3 to 50 μm, and may be changed to various diameters according to characteristics of the liquid crystal display device to which the prism sheet 110 is applied.

Further, the materials of the diffusion beads 32a and 32b, the diffusion agents that may be included in the diffusion beads 32a and 32b, and the like, are substantially the same as in the prism sheet 100 of FIG. 1 according to an embodiment of the present invention. In the following description, redundant descriptions are omitted.

Subsequently, a prism sheet according to another embodiment of the present invention will be described with reference to FIGS. 5 and 6. 5 is a perspective view of a prism sheet according to another embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along the line VI-VI 'of FIG. 5.

5 and 6, the prism sheet 120 according to another embodiment of the present invention is a prism sheet according to an embodiment of the present invention except for the diffusion beads 32 (FIGS. 1 and FIG. Substantially the same as 100). Therefore, a description will be given of the difference between the prism sheet (100 of FIGS. 1 and 2) according to an embodiment of the present invention and the prism sheet 120 according to another embodiment of the present invention.

The prism sheet 120 according to another embodiment of the present invention includes a transparent substrate 10, a plurality of prism arrays 20, and a plurality of diffusion beads 34a, 34b, 34c.

For example, a plurality of three-dimensional prismatic arrays 20 are repeatedly arranged on the transparent substrate 10 in parallel with one side of the transparent substrate 10, and a plurality of diffusion beads 34a are disposed between the prism arrays 20. , 34b, 34c).

The diffusion beads 34a, 34b, 34c which evenly spread incident light have at least two kinds of diameters in the same row. That is, diffusion beads 34a, 34b, 34c having various diameters are positioned between the prism arrays 20.

The diameters of the diffusion beads 34a, 34b, and 34c may be, for example, about 3 μm to about 50 μm, and may be changed to various diameters according to characteristics of the liquid crystal display device to which the prism sheet 120 is applied.

In addition, a diffusing agent that may be included in the material of the diffusion beads 34a, 34b, 34c, and the diffusion beads 34a, 34b, 34c, etc., in the prism sheet (100 in FIGS. 1 and 2) according to an embodiment of the present invention. Since it is substantially the same as, and the duplicate description is omitted here.

Subsequently, a prism sheet according to another embodiment of the present invention will be described with reference to FIGS. 7 and 8. 7 is a perspective view of a prism sheet according to another embodiment of the present invention, and FIG. 8 is a cross-sectional view taken along the line VII-VII 'of FIG. 7.

7 and 8, the prism sheet 130 according to another embodiment of the present invention is a prism sheet according to an embodiment of the present invention except for the diffusion beads 32 (FIGS. 1 and FIG. Substantially the same as 100). Therefore, a description will be given focusing on the difference between the prism sheet (100 of FIGS. 1 and 2) according to an embodiment of the present invention and the prism sheet 130 according to another embodiment of the present invention.

The prism sheet 130 according to another embodiment of the present invention includes a transparent substrate 10, a plurality of prism arrays 20, and a plurality of diffusion beads 36.

On the transparent substrate 10, for example, a plurality of three-dimensional prismatic arrays 20 are repeatedly arranged in parallel with one side of the transparent substrate 10, and a plurality of diffusion beads 36 are disposed between the prism arrays 20. ) Is located.

Diffusion beads 36 that evenly spread the incident light have substantially the same diameter over the entire prism sheet 130. In addition, the diffusion bead 36 includes a plurality of projections that can further increase the light diffusion efficiency.

The diameter of the diffusion beads 36 may be, for example, 3 to 50 μm, and may be changed to various diameters according to characteristics of the liquid crystal display device to which the prism sheet 130 is applied.

In addition, the material of the diffusion bead 36 and the diffusion agent that may be included in the diffusion bead 36 and the like is substantially the same as the prism sheet (100 in FIGS. 1 and 2) according to an embodiment of the present invention, so The description is omitted.

Although not shown, even if the diffusion beads 36 positioned between the prism arrays 20 have different diameters in different rows, the diffusion beads 36 may include a plurality of protrusions on the surface thereof, and the same row Of course, even if it has at least two kinds of diameter in the diffusion beads 36 may include a plurality of projections on the surface of course.

Subsequently, a prism sheet according to another embodiment of the present invention will be described with reference to FIGS. 9 and 10. 9 is a perspective view of a prism sheet according to still another embodiment of the present invention, and FIG. 10 is a cross-sectional view taken along the line VII- ′ ′ of FIG. 9.

9 and 10, the prism sheet 140 according to another embodiment of the present invention is one of the present invention except that the diffusion beads 38 and the prism array 21 are integrally formed. It is substantially the same as the prism sheet 100 (FIGS. 1 and 2) according to the embodiment. Therefore, a description will be given focusing on the difference between the prism sheet (100 of FIGS. 1 and 2) according to an embodiment of the present invention and the prism sheet 140 according to another embodiment of the present invention.

The prism sheet 140 according to another embodiment of the present invention includes a transparent substrate 10, a plurality of prism arrays 21, and a plurality of diffusion beads 38.

For example, a plurality of three-dimensional prism arrays 21 are repeatedly arranged on the transparent substrate 10 in parallel with one side of the transparent substrate 10, and a plurality of diffusion beads 38 are interposed between the prism arrays 21. ), But the prism array 21 and the diffusion beads 38 are integrally formed.

Diffusion beads 38 that evenly spread incident light have substantially the same diameter over the entire prism sheet 140. The diameter of the diffusion bead 38 may be, for example, 3 to 50 μm, and may be changed to various diameters according to characteristics of the liquid crystal display device to which the prism sheet 140 is applied.

In addition, the material of the diffusion bead 38 and the diffusion agent that may be included in the diffusion bead 38 and the like are substantially the same as in the prism sheet (100 in FIGS. 1 and 2) according to one embodiment of the present invention, In the following description, redundant descriptions are omitted.

Although not shown, the diffusion beads 38 located between the prism arrays 21 may have different diameters in different rows, at least two kinds of diameters in the same row, and a plurality of projections on the surface thereof. Of course, it may include.

As described above, the prism sheet according to the embodiments of the present invention includes a diffusion function of diffusing light by a plurality of diffusion beads positioned between the prism arrays, in addition to the original function of increasing brightness by refracting and condensing light. In the case of the backlight assembly including the prism sheet, a separate diffusion sheet may not be used.

Subsequently, a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to FIG. 11. 11 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIG. 11, the liquid crystal display 200 according to the exemplary embodiment may include a backlight assembly 210, a liquid crystal display panel 220, upper and lower storage containers 230 and 240, and an intermediate mold. A middle mold frame 250, a bottom mold frame 260, and front and back covers 280 and 290.

First, the backlight assembly 210 will be described with reference to FIGS. 11 and 12. 12 is a cross-sectional view of the backlight assembly according to an embodiment of the present invention.

As shown in FIG. 12, the backlight assembly 210 includes a light guide plate 211, a light source 212, a reflector 213, a prism sheet 100, and a protective sheet 214.

The light guide plate 211 guides the light supplied to the light source 212 toward the liquid crystal display panel 220. The light guide plate 211 is made of a plastic-based material such as acryl, and various patterns are provided on the lower surface of the light guide plate 211 to change the traveling direction of light incident into the light guide plate 211 toward the liquid crystal display panel 220. Printed and formed. Here, although the light guide plate 211 has a flat plate shape, the light guide plate 211 may have a wedge shape in which the thickness thereof gradually decreases toward one end.

The light source 212 may be positioned at both sides of the light guide plate 211, for example, and may be formed of a long cylindrical cold cathode fluorescent lamp (CCFL). Although not illustrated, the light source 212 may be formed of, for example, a flat fluorescent lamp. In this case, the light guide plate 211 may be omitted. In addition, although not shown, when the light guide plate has a wedge shape, the light source 212 may be located only at one side of the light guide plate.

The reflection plate 213 is disposed on the rear surface of the light guide plate 211 and reflects light emitted to the rear surface of the light guide plate 211 toward the upper surface side of the light guide plate 211. The reflective plate 213 reduces the loss of light incident on the liquid crystal display panel 220 and improves the uniformity of light transmitted to the upper surface of the light guide plate 211.

In the prism sheet 100 positioned on the light guide plate 211, a plurality of prism arrays 20 are arranged on an upper surface of the transparent substrate 10, and a plurality of diffusion beads 30 are disposed therebetween, and It consists of two sheets, and arrange | positions each prism array 20 mutually staggered at a predetermined angle. The prism sheet 100 refracts light emitted through the light guide plate 211 in a direction perpendicular to the liquid crystal panel 220 and collects light. In addition, the prism sheet 100 diffuses light by the diffusion beads 30 positioned between the prism arrays 20 to improve the brightness uniformity of the light, widen the viewing angle, and hide the pattern of the light guide plate 211. do.

Since the prism sheet 100 is as described above, detailed description thereof will be omitted here. In addition, although FIG. 12 illustrates the prism sheet 100 according to an embodiment of the present invention, a diffusion sheet (110 of FIG. 3 and 120 of FIG. 5) according to another embodiment or another embodiment of the present invention is illustrated. 7, 130 and 140 of FIG. 9 may also be disposed on the light guide plate 211 similarly to the prism sheet 100 according to an embodiment of the present invention.

The protective sheet 214 positioned on the upper portion of the prism sheet 100 may serve to protect the surface of the prism sheet 100 and to diffuse light in order to uniformize light distribution.

In addition, although not shown, in some cases, a diffusion sheet may be further disposed between the light guide plate 211 and the prism sheet 100.

Referring back to FIG. 11, a liquid crystal display panel 220 displaying an image is positioned on the backlight assembly 210 having the above-described configuration. The liquid crystal display panel 220 includes a first display panel 221 including a color filter which allows light provided from the backlight assembly 210 to be expressed in a predetermined color by red, green, and blue pixels surrounded by a black matrix, The display panel includes a second display panel 222 including a thin film transistor in a matrix array, and a liquid crystal layer (not shown) formed between the first display panel 221 and the second display panel 222.

The liquid crystal display panel 220 includes data and gate printed circuit boards 225 and 226 in addition to the first display panel 221 and the second display panel 222. The data and gate printed circuit boards 225 and 226 are connected to the liquid crystal display panel 220 by a data and gate tape carrier package 223 and 224, which is a type of flexible circuit board. The gate printed circuit boards 225 and 226 apply driving signals and timing signals to the gate lines and the data lines of the thin film transistors in order to control the arrangement angles of the liquid crystals constituting the liquid crystal layer and when the liquid crystals are arranged.

The upper accommodating container 230 fixes the liquid crystal display panel 220 by combining the intermediate mold frame 250 provided on the upper side of the lower accommodating container 240 with a coupling means such as a screw and a plurality of coupling windows on the sidewalls. (Not shown).

The lower storage container 240 is a container for storing the backlight assembly 210, and may have a shape in which the backlight assembly 210 may be seated, for example, a quadrangular shape, and is disposed on the rear surface of the lower storage container 240. Screw grooves (not shown) are formed.

The lower mold frame 260 accommodates the lower accommodating container 240, and a coupling protrusion that hooks a coupling window (not shown) formed on the upper accommodating container 230 to a sidewall of the lower mold frame 260. (Not shown) are provided in plural.

The printed circuit board cover 270 is grounded to the lower housing container 240 by a coupling means such as a screw to block shorts and electromagnetic waves generated in the data printed circuit board 225.

As described above, the backlight assembly including the prism sheets and the liquid crystal display according to the exemplary embodiments of the present invention include a prism sheet including diffusion beads between the prism arrays, thereby providing excellent light diffusion even when the diffusion sheet is not used. Can have efficiency.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

According to the prism sheet, the backlight assembly including the same, and the liquid crystal display device according to the present invention as described above, since the prism sheet includes a diffusion bead, the prism sheet has a complex function of light refraction, condensing, and light diffusion, thereby degrading the performance of the backlight assembly. It is possible to achieve a light and thin reduction of the liquid crystal display device.

Claims (14)

Transparent substrates; A prism array in which a plurality of three-dimensional structures are repeatedly formed on the transparent substrate; And A prism sheet comprising a plurality of diffusion beads positioned between the prism arrays. The method of claim 1, Said plurality of diffusion beads having substantially the same size in the same row. The method of claim 2, And the plurality of diffusion beads have different sizes in different rows. The method of claim 1, And said plurality of diffusion beads have at least two kinds of diameters in the same row. The method of claim 1, The plurality of diffusion beads comprising a plurality of projections on the surface. The method of claim 1, The plurality of diffusion beads are prism sheet having a diameter of 3 to 50㎛. The method of claim 1, The plurality of diffusion beads further comprise a diffusing agent. The method of claim 7, wherein The diffusing agent is a prism sheet which is an organic particle or an inorganic particle. The method of claim 8, The organic particles may include at least one selected from acrylic particles, olefin particles, copolymer particles of acrylic and olefin copolymers, and multilayer multicomponent particles. The method of claim 8, The inorganic particles include at least one selected from silicon oxide, aluminum oxide, titanium oxide, zirconium oxide and magnesium fluoride. The method of claim 1, And the prism array is selected from at least one of a linear arrangement of parallel triangular prisms, a square pyramid prism structure, a triangular pyramid prism structure, a hemispherical prism structure and a non-spherical prism structure. The method of claim 1, The prism array and the diffusion beads are integral with the prism sheet. 13. A backlight assembly comprising the prism sheet according to any one of claims 1 to 12. A liquid crystal display device comprising the prism sheet according to any one of claims 1 to 12.

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