KR20090125920A - Optical sheet, back light unit and liquid crystal display device comprising the same - Google Patents

Abstract

PURPOSE: An optical sheet, a backlight unit and a liquid crystal display device including the same are provided to improve display quality by improving a light diffusion rate and luminance uniformity through an optical sheet. CONSTITUTION: An optical sheet includes a base material(110) and a protrusion part(120) formed on the base material. The protrusion part includes a plurality of convexes(120a), a plurality of concaves(120b), and a plurality of first diffusion particles(122). The protrusion part has a prism shape. The base material is made of a transparent material in order to transmit a light emitted from a light source. The transparent material selectively includes at least two or more things among polyethylene terephthalate, polycarbonate, polypropylene, polyethylene, polystyrene, and polyepoxy. The protrusion part diffuses an incident light through the first diffusion particles, and includes a resin(121) having a fixed adhesive property.

Description

Optical Sheet, Back Light Unit And Liquid Crystal Display Device Comprising The Same}

The present invention relates to an optical sheet, a backlight unit including the same, and a liquid crystal display device.

In recent years, the display field for visually expressing various electrical signal information has been rapidly developed. Accordingly, various flat panel displays (FPDs) with excellent characteristics such as thinning, light weight, and low power consumption are being developed. It has been introduced and rapidly replaced the existing cathode ray tube (CRT).

Examples of such flat panel displays include liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs), and electroluminescent displays (ELDs). The liquid crystal display device has a high contrast ratio and is excellent in moving image display, and is currently being actively used in the field of display screens, monitors, and TVs for notebooks.

In general, the liquid crystal display may include a backlight unit disposed below the liquid crystal panel to provide light to the liquid crystal panel, in addition to the liquid crystal panel displaying an image with the light receiving display device.

The backlight unit may include a light source, an optical sheet, and the like to provide light to the liquid crystal panel. Here, the optical sheet may include a diffusion sheet, a protective sheet, a prism sheet, and the like.

Accordingly, the present invention can provide an optical sheet, a backlight unit including the same, and a liquid crystal display device capable of improving luminance uniformity and light diffusion rate.

According to the above-described problem solving means, the present invention is located on the base material, the base material, and includes a protrusion including a plurality of acids and a plurality of first diffusion particles, at least any one of the cross-sectional area of the protrusion perpendicular to the longitudinal direction of the acid The total cross-sectional area of the first diffusion particles formed in the cross-sectional area of the protrusions relative to the cross-sectional area of the cross-sectional area of the first diffusion particles includes not less than 1 to 0.04 and not more than 1 to 0.12.

In addition, the plurality of first diffusion particles have a diameter of the first diffusion particles corresponding to the cumulative volume 50% of the cumulative volume 100% of the total volume of the first diffusion particles is X㎛, X-1.5㎛ more than X + 1.5㎛ The cumulative volume of the first diffusion particles having a diameter may include 40% or more and 80% or less of the cumulative volume of the entire first diffusion particles.

In addition, the diameters of the plurality of first diffusion particles may include 1 μm or more and 10 μm or less.

In addition, X may contain 1 micrometer or more and 4 micrometers or less.

In addition, the plurality of first diffusion particles may include a bead.

In addition, the plurality of first diffusion particles may include polymethyl methacrylate (PMMA), polystyrene, and at least one of two or more of silicon.

In addition, the substrate may include at least one or two or more of polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene, and polyepoxy.

In addition, the protrusions may include ones each having a different width.

In addition, the protrusions may include different heights.

In addition, the protrusions may include a continuous curvature having different heights and randomly changing left and right amplitudes.

In addition, a primer layer may be further included between the substrate and the protrusion.

In addition, the primer layer may include at least one or two or more of acrylic, ester and urethane.

In addition, the thickness of a primer layer may contain 5 nm or more and 300 nm or less.

In addition, a protective layer may be further included below the substrate.

In addition, the protective layer may include a base material and a plurality of second diffusion particles.

In addition, the diameter of the second diffusion particles may include those of 1 μm or more and 10 μm or less.

On the other hand, in another aspect, the present invention includes a light source and an optical sheet positioned on the light source.

Meanwhile, in another aspect, the present invention includes a light source and a liquid crystal panel positioned on an optical sheet positioned on the light source.

An optical sheet, a backlight unit including the same, and a liquid crystal display device according to an exemplary embodiment of the present invention may improve luminance uniformity and light diffusion rate through the optical sheet.

Therefore, there is an advantage that the display quality of the liquid crystal display device can be improved.

Hereinafter, with reference to the accompanying drawings, the specific content for the practice of the present invention will be described.

1A and 1B illustrate an optical sheet according to a first embodiment of the present invention.

1A and 1B, an optical sheet according to a first embodiment of the present invention includes a substrate, a protrusion positioned on the substrate and including a plurality of acids and a plurality of first diffusion particles, and perpendicular to a length direction of the acid. The total area of the first diffusion particles formed in the cross-sectional area of the protrusion relative to the cross-sectional area of at least any one of the cross-sectional areas of the protrusions is 1 to 0.04 or more and 1 to 0.12 or less.

In the optical sheet according to the first embodiment of the present invention, the protrusion 120 positioned on the substrate 110 may have a prism shape. The plurality of protrusions 120 having a prism shape may include a plurality of peaks 120a and valleys 120b, and the distance P between the peaks 120a and the angle A of the peaks may be constant.

The substrate 110 may be transparent to transmit light emitted from the light source. To this end, the substrate 110 may be formed of a transparent material. The material of the substrate 110 may select at least one or two or more of polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene and polyepoxy.

The substrate 110 may have a predetermined thickness. As such, by forming the substrate 110 to a predetermined thickness, the substrate 110 may exhibit excellent performance in terms of processability and may have a property of being able to bend like a film. For example, the substrate 110 may have a predetermined thickness of 10 µm or more and 1000 µm or less. At this time, when the thickness of the base material 110 is 10 micrometers or more, it can thin in the limit which ensures the mechanical strength and thermal stability of a sheet | seat. In addition, when the thickness of the substrate 110 is 1000 µm or less, mechanical strength and heat resistance can be ensured to the maximum within the limit of securing the flexibility of the optical sheet.

Accordingly, some of the light incident from the light source is transmitted through the substrate 110 and some is reflected from the substrate 110 toward the lower light source. At this time, the light reflected toward the light source is reflected again to be incident to the substrate 110, a part of the light incident on the substrate 110 is transmitted through the substrate 110, and a portion of the light from the substrate 110 toward the lower light source Reflected again. Thereby, the efficiency of the light incident from the light source can be improved.

In addition, the substrate 110 is illustrated as one layer but may be formed of a plurality of layers.

The protrusion 120 positioned on the substrate 110 may diffuse light incident from an external light source through the first diffusion particles formed therein.

In this case, the protrusion 120 may be formed to include a resin 121 having a predetermined adhesive property.

 Resin 121 may be an acrylic resin, for example, unsaturated polyester, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, Methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxy ethyl acrylate, acrylamide, methrol acrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl Acrylic, urethane, epoxy, melamine, or the like, such as acrylate, 2-ethylhexyl acrylate polymer or copolymer or terpolymer, may be used, but is not limited thereto.

The plurality of first diffusion particles 122 formed in the protrusion may be a plurality of beads, and may be formed of at least one or two or more of polymethyl methacrylate (PMMA), polystyrene, and silicone.

Here, the first diffusion particles 122 with respect to the resin 121 may be included in 1 to 10 parts by weight. If the content of the first diffused particles 122 with respect to the resin 121 is 1 part by weight or more, it is possible to prevent a problem that light incident from the light source is difficult to diffuse by the first diffused particles 122, and the resin When the content of the first diffusion particles 122 with respect to 121 is 10 parts by weight or less, there is an advantage that can prevent the transmittance of light incident from the light source is lowered.

In this case, the diameters of the plurality of first diffusion particles 122 distributed in the resin 121 may not be uniform but may have an irregular distribution.

In addition, the first diffusion particles 122 distributed in the resin 121 may have an irregular distribution without having a regular distribution in the resin 121.

In addition, as shown in FIG. 1B, the optical sheet may further include a primer layer 130 between the substrate 110 and the protrusion 120.

The primer layer 130 may be formed by a primer treatment process. The primer treatment may serve to improve adhesion to the polymer film and the UV resin by performing a polymer treatment on a general polymer film.

In this case, as the polymer material used for the primer treatment, acrylic (Acryl), ester (Ester) or urethane (Urethane) may be used, and a water-soluble polymer material may be used to prevent the risk of fire.

The primer treatment process may be performed by applying the above-described polymer material on a substrate to be primed and coating it using a coater device.

In addition, the thickness h1 of the primer layer 130 may have 5 nm or more and 300 nm or less.

Here, if the thickness h1 of the primer layer 130 is 5 nm or more, the height of the primer layer 130 may be too thin to prevent the disadvantage of not exhibiting an improvement in adhesive strength, and the thickness of the primer layer 130 may be 300 nm. If it is below, there is an advantage that can prevent coating staining or agglomeration of the polymer material occurs during the primer treatment process.

Table 1 shows the results of measuring the transmission characteristics and the adhesion characteristics according to the thickness of the primer layer 130 as a table.

Thickness of primer layer (nm) Transmission characteristics Adhesive properties 3 ◎ x 5 ◎ ○ 10 ◎ ○ 30 ◎ ○ 90 ○ ○ 140 ○ ○ 200 ○ ◎ 250 ○ ◎ 300 ○ ◎ 400 x ◎

◎: very good, ○: excellent, x: bad

As shown in Table 1, the primer layer 130 may be finely adjusted for the thickness to improve brightness, color coordinates, and the like.

Therefore, when the primer treatment between the substrate 110 and the protrusion 120, by adjusting the thickness of the primer layer 130, there is an effect that can improve the light transmittance and adhesive properties.

On the other hand, the primer layer 130 may induce such that the substrate 110 and the protrusion 120 are bonded to each other through chemical bonding, unlike the adhesive or adhesive that is physically bonded.

That is, the material of the substrate 110 may be poly-based, and the material of the protrusion 120 may be UV (ultra violet) resin series. Here, when the general physical coupling between the substrate 110 and the protrusion 120 is attempted, it is difficult to expect superior adhesion since the interfaces are smoothly attached to each other. However, attempting chemical bonding by forming the primer layer 130 between the substrate 110 and the protrusion 120 may expect superior adhesion than the physical bonding and protect the mutually attached interfaces.

In addition, the optical sheet may further include a protective layer 140 under the substrate 110.

The protective layer 140 may serve to improve heat resistance of the optical sheet. In more detail, the protective layer 140 may include a resin-based base material 141 and a plurality of second diffusion particles 142 dispersed in the base material 141.

The base material 141 is transparent and may use an acrylic resin having excellent heat resistance and mechanical properties. The acrylic resin may be, for example, polyacrylate or polymethyl methacrylate.

The second diffusion particles 142 formed in the protective layer 140 may be beads, and may be manufactured using the same or different types of resins as the base material 141, and may be 10 to 50 parts by weight based on the base material 141. May be included. The diameter of the second diffusion particles 142 may be appropriately selected according to the thickness of the substrate 110, and may be 5 μm or more and 7 μm or less. Thereby, the heat resistance characteristic of an optical sheet can be improved more efficiently.

In the first embodiment of the present invention, the diameter of the second diffusion particles 142 may be substantially the same, the distribution in the base material 141 may be regular. Unlike this, the diameters of the second diffusion particles 142 are also different from each other, and the distribution in the base material 141 may be irregular.

The protective layer 140 may prevent the optical sheet from being deformed by heat generated from the light source. That is, wrinkles do not occur in the optical sheet by the protective layer 140 having high heat resistance, and even when the optical sheet is deformed at a high temperature, the restoring force of returning to the original optical sheet shape again at room temperature is excellent.

In addition, the protective layer 140 may also serve to prevent scratches on the optical sheet due to external impact or other physical force.

2 is a cross-sectional view of an optical sheet according to a first embodiment of the present invention.

2, the total cross-sectional area of the first diffusion particles formed in the cross-sectional area of the protrusion relative to the cross-sectional area of at least one of the protrusions perpendicular to the longitudinal direction of the mountain is 1 to 0.04 or more and 1 to 0.12 or less.

The protrusion includes a plurality of mountains, and valleys may be formed between the mountains and the neighboring mountains. That is, it can be said that a mountain can be formed between the valley and the neighboring valley.

The cross-sectional area of the protrusion perpendicular to the longitudinal direction of the peak or the valley length can be easily divided by dividing the height (L) of the peak by the width (W) of the valley and the neighboring valley by 1/2. In addition, the cross-sectional area of the first diffusion particles can be easily known by knowing the diameter of the first diffusion particles.

The diameter of the first diffusion particles 122 may be 1 μm to 5 μm. When the diameter of the first diffusion particles 122 is small, the density of the first diffusion particles 122 may be increased inside the first diffusion part 120 to improve the light diffusion rate of the optical sheet 100, but the first diffusion If the diameter of the particle 122 is too small, interference of light incident from an external light source may occur. As a result, the diameter of the first diffusion particles 122 may be 0.5 μm or more, whereby the light diffusion rate may be improved as much as possible without interference of light.

In addition, when the diameter of the first diffusion particles 122 is large, a problem arises in that the protrusions 120 need to be thickened to secure the light diffusion rate of the optical sheet 100, which makes it difficult to manufacture a thin optical sheet. A problem occurs. Thereby, by making the diameter of the 1st diffuse particle 122 into 5 micrometers or less, thinning of an optical sheet can be achieved within the limit that a light-diffusion rate does not fall. Accordingly, the first diffusion particles 122 formed in the cross-sectional area of the protrusion may be formed of five or more and 15 or less.

The total cross-sectional area of the first diffusion particles 122 formed in the cross-sectional area of the protrusion relative to the cross-sectional area of at least one of the plurality of protrusions may be 1 to 0.04 or more and 1 to 0.12 or less.

That is, when the total cross-sectional area of the first diffused particles 122 formed in the cross-sectional area of the at least one protrusion is at least one of 0.04 or more, the density of the first diffused particles 122 is low, so that the light of the optical sheet is reduced. The diffusion rate can be prevented from being lowered, and if it is 1 to 0.12 or less, it is possible to prevent the occurrence of interference of light incident from an external light source.

Accordingly, when the density of the first diffusion particles 122 is increased, the light diffusion rate can be improved as much as possible in a range where light interference does not occur.

Table 2 below shows the results of measuring the density of the first diffusion particles 122 and the interference of the light according to the overall cross-sectional area of the first diffusion particles 122 formed in any one of the cross-sectional area of the entire projection.

Overall cross-sectional area of the first diffused particles formed in the cross-sectional area of the protrusion Density of first diffusion particles Light interference 1 set 0.02 x ◎ 1 set 0.03 x ◎ 1 set 0.04 ○ ◎ 1 to 0.05 ○ ◎ 1 set 0.06 ○ ○ 1 set 0.07 ○ ○ 1 set 0.08 ○ ○ 1 set 0.10 ◎ ○ 1 set 0.12 ◎ ○ 1 set 0.14 ◎ x

                                       ◎: very good, ○: excellent, x: bad

As shown in Table 2, the density characteristics of the first diffusion particles 122 and the interference characteristics of the light may vary depending on the overall cross-sectional area of the first diffusion particles 122 formed in the cross-sectional area of any one of the cross-sectional area of the entire protrusion. will be.

That is, as the overall cross-sectional area of the first diffused particles 122 formed in the cross-sectional area of the protrusion increases, the density of the first diffused particles 122 increases, so that light diffusion may be improved, but interference of light may occur, As the overall cross-sectional area of the first diffused particles 122 decreases, interference of light may be prevented, but the density of the first diffused particles 122 may decrease to decrease the light diffusion rate. Accordingly, the total cross-sectional area of the first diffusion particles 122 formed in the cross-sectional area of the protrusion relative to the cross-sectional area of at least one of the plurality of protrusions has a range of 1 to 0.04 or more and 1 to 0.12 or less, so that interference of light The light diffusion rate can be improved as much as possible in the range that does not occur.

3 is for explaining the cumulative volume of the first diffusion particles according to the first embodiment of the present invention.

Referring to FIG. 3, the cumulative volume according to the diameter of the first diffusion particles 122 is shown for the entire first diffusion particles 122 included in the protrusion. Here, the horizontal axis represents the diameter (μm) of the first diffused particles 122, the left vertical axis represents the volume (%) occupied by each first diffused particle 122, the right vertical axis represents the entire first diffused particle 122 Represents the cumulative volume of (%).

A range of X-1.5 μm to X + 1.5 μm, centering on the first diffused particle 122 corresponding to a diameter of X μm corresponding to a cumulative volume of 50% with respect to 100% of the cumulative volume of the entire first diffused particle 122 It can be seen that the cumulative volume occupied by the first diffusion particles 122 corresponding to the diameter is in the range of about 40% or more and 80% or less. Herein, the diameter of the first diffusion particles 122 may be 1 μm or more and 5 μm or less, and X may be 2 μm or more and 3 μm or less.

In addition, the first diffused particles 122 having a diameter of X μm occupy about 30% of the volume of the entire first diffused particles 122, and the first diffused particles 122 having a diameter of about X-1.5 μm are about 10%. %, The first diffusion particles 122 having a diameter of X + 1.5㎛ may occupy about 10% of the volume.

For example, when the total volume of the first diffusion particles 122 present in the first diffusion unit 120 is 100%, the diameter corresponding to 2.5 μm from the first diffusion particles 122 having a diameter of 1 μm If the cumulative volume to the first diffusion particles having a 50%, the diameter of the first diffusion particles 122 corresponding to the cumulative volume 50% is 2.5㎛.

In addition, the cumulative volume of the first diffusion particles 122 corresponding to a diameter in the range of X-1.5 μm to X + 1.5 μm is 40% or more and 80% or less, when X μm is 2.5 μm and 2 μm or more and 3 μm. The cumulative volume of the first diffusion particles 122 having a diameter of 40% or more and 80% or less.

Table 3 shows the results of measuring the diffusion effect and the brightness of the optical sheet according to the cumulative volume of the first diffusion particles corresponding to the diameter in the range of 1㎛ 4㎛ when X is 2.5㎛.

Cumulative volume (%) of the first diffusion particles having a diameter in the range of 2 ㎛ to 3 ㎛ Diffusion effect Luminance 20 × ◎ 30 × ◎ 40 ○ ◎ 50 ○ ○ 60 ○ ○ 70 ◎ ○ 80 ◎ ○ 90 ◎ ×

                                      ×: bad, ○: good, ◎: very good

Referring to Table 3, in the first embodiment of the present invention, a diameter of 2.5 μm corresponding to 50% of the cumulative volume of the cumulative volume of all the first diffusing particles among the plurality of first diffusion particles included in the protrusions When the cumulative volume occupied by the first diffusion particles corresponding to the diameter in the range of 1 µm to 4 µm is formed in the range of about 40% to 80%, the diffusion effect and the luminance are excellent. Able to know.

Accordingly, by forming the first diffusion particles having a cumulative volume of 40% or more and 80% or less of the first diffusion particles corresponding to a diameter in the range of X-1.5 μm to X + 1.5 μm, the light incident from the light source is formed. Can spread. One

4 is for explaining various examples of the protrusion according to the first embodiment of the present invention.

In the protrusion 120 illustrated in FIG. 4A, the distance P between the mountains forming the prism shape and the angle A of the mountains may be regularly different. The protrusion 120 having such a shape may have a diffusion effect in which a change in refractive index of light incident from the substrate 110 occurs differently in a predetermined region.

The protrusion 120 shown in (b) may be formed in a form in which the distance P between the mountains forming the prism shape and the angle A of the mountain are small, that is, the densities of the mountains and the valleys are high. Protruding portion 120 having such a shape may have an effect of increasing the straightness rather than the light diffusion effect because the refractive index of the light incident from the substrate 110 is dense.

Protruding portion 120 shown in (c) may be formed in a random shape of the peaks and valleys forming the prism shape. The protrusion 120 having such a shape may have a diffusion effect in which a refractive angle of light incident from the substrate 110 occurs randomly.

The prism shape included in the protrusions 120 shown in FIGS. 3A to 3C may have one or more distances P and angles A between the mountains, which may change the shape of the bone. Can be. The distance P between the mountains may be 20 μm or more and 60 μm or less, the angle of the mountain A may be 70 ° or more and 110 ° or less, and the height of the protrusion 120 may be 10 μm or more and 40 μm or less. But it is not limited thereto.

Protruding portion 120 shown in (d) may be formed in the shape of a mountain and a valley forming a prism in a streamline form, not a straight form. The protrusion 120 having such a shape may have a diffusion effect in which a refractive angle of light incident from the substrate 110 is wider.

The plurality of protrusions 120 described above with reference to FIG. 4 illustrate various cross sections of the prism. However, the shape of the protrusion 120 is different from each other on the plane or side, it can be seen more clearly with reference to Figures 5a to 5d.

5A to 5D illustrate the planar or side surfaces of the protrusions according to the first embodiment of the present invention.

5A to 5D illustrate the side surfaces of the protrusions through various examples, and thus the detailed description thereof will be omitted since they are substantially the same as the contents described with reference to FIGS. 1A to 4.

In this case, as shown in FIGS. 5A to 5D, the peaks or valleys of the protrusions 120 may form continuous bends in the longitudinal direction of the protrusions 120, and the bends may be regular or irregular.

That is, the mountains of the protrusions 120 may have a zigzag shape in which left and right are random, and the average horizontal amplitude of the mountains may be 1 μm or more and 20 μm or less.

In addition, the valley of the protrusion 120 may have a zigzag shape in which the left and right are random, and the average horizontal amplitude of the valley may be 1 μm or more and 20 μm or less.

In addition, the height of the peaks of the protrusions 120 may vary continuously from each bottom surface, and may form regular or irregular bends. In this case, an average height difference of the mountains of the protrusion 120 may be 1 μm or more and 20 μm or less.

Therefore, the backlight unit including the optical sheet according to the first embodiment of the present invention described so far operates as follows.

Therefore, the backlight unit including the optical sheet according to the first embodiment of the present invention operates as follows.

Light generated from the light source is incident on the optical sheet. A part of the light incident on the optical sheet collides with the first diffusion particles of the protrusion to change the path, and the other part of the light passes through the exit surface of the first diffusion part to the liquid crystal panel.

The light whose path is changed by hitting the first diffuser is hit by another adjacent first diffuser and the path is changed again. The path is changed again.

Finally, the light passing through the exit surface of the first diffusion part is incident evenly onto the liquid crystal panel.

As a result, the light incident on the optical sheet is reflected by the plurality of first diffusion particles formed in the protrusion part and diffuses while changing its propagation path, thereby improving luminance uniformity.

6A and 6B illustrate the configuration of a backlight unit including an optical sheet according to example embodiments.

In FIG. 6A, an edge type backlight unit is illustrated as the backlight unit, and the overlapping description is omitted since the optical sheet of the present invention is the same as the above-described optical sheet.

6A and 6B, the backlight unit 400 according to an exemplary embodiment of the present invention may be provided in a liquid crystal display and may provide light to a liquid crystal panel provided in the liquid crystal display.

The backlight unit 400 may include a light source 420 and an optical sheet 430. In addition, the backlight unit 400 may further include a light guide plate 440, a reflective plate 450, a bottom cover 460, and a mold frame 470.

The light source 420 may generate light by using driving power applied from the outside, and may emit the generated light.

For example, at least one light source 420 may be formed on one side of the light guide plate 440 along the long axis direction of the light guide plate 440, or at least one light source 420 may be formed on each side of the light guide plate 440. . Here, the light emitted from the light source 420 is incident directly into the light guide plate 440, or the light source housing 522 formed to surround a portion of the light source 420, for example, about 3/4 of the outer peripheral surface of the light source 420. After reflection, the light may enter the light guide plate 440.

The light source 420 includes a Cold Cathode Fluorescent Lamp (CCFL), a Hot Cathode Fluorescent Lamp (HCFL), an External Electrode Fluorescent Lamp (EEFL), and a Light Emitting Diode (Light Emitting Diode). : LED), but is not limited thereto.

The optical sheet 430 may be disposed on the light guide plate 440. The optical sheet 430 may serve to diffuse light incident from the light source 420.

In the optical sheet according to the embodiments of the present invention, the total cross-sectional area of the first diffusion particles formed in the cross-sectional area of the protrusion relative to the cross-sectional area of at least one of the plurality of protrusions is formed in the range of 1 to 0.04 or more and 1 to 0.12 or less. There is an advantage that the luminance can be made uniform while improving the transmittance and the light diffusion.

Although not shown in the present embodiment, a protective sheet may be further included.

The light guide plate 440 may be disposed to face the light source 420, and may guide the light so that light incident from the light source 420 is emitted upward.

The reflection plate 450 may be disposed under the light guide plate 440, and may reflect light emitted downward from the light source 420 through the light guide plate 440 upward.

The bottom cover 460 may include a bottom part 562 and a side part 564 formed to extend from the bottom part 562 to form an accommodation space, and the light source 420 and the optical sheet 430 may be formed in the accommodation space. The light guide plate 440 and the reflective plate 450 may be accommodated.

The mold frame 470 may be formed in a substantially rectangular frame shape and may be fastened with the bottom cover 460 from the top of the bottom cover 460 in a top down manner.

7A and 7B illustrate a configuration of a backlight unit including an optical sheet according to another exemplary embodiment of the present disclosure.

7A and 7B illustrate a direct backlight unit as the backlight unit, but the present invention is not limited thereto. Meanwhile, the backlight unit illustrated in FIGS. 7A and 7B is substantially the same as the backlight unit illustrated in FIGS. 6A and 6B except for the arrangement of light sources and a change in components thereof, and thus, redundant descriptions thereof are omitted. Only its features will be described.

Referring to FIGS. 7A and 7B, the backlight unit 500 according to another exemplary embodiment of the present invention may be provided in the liquid crystal display and may provide light to the liquid crystal panel provided in the liquid crystal display.

The backlight unit 500 may include a light source 520 and an optical sheet 530. In addition, the backlight unit 500 may further include a reflective plate 550, a bottom cover 560, a mold frame 570, and a diffusion plate 580.

At least one light source 520 may be disposed under the diffuser plate 580. For this reason, the light emitted from the light source 520 may be incident directly to the diffuser plate 580.

The optical sheet 530 may be disposed on the diffuser plate 580. The optical sheet 530 may serve to condense the light incident from the light source 520.

In the optical sheet according to the embodiments of the present invention, the total cross-sectional area of the first diffusion particles formed in the cross-sectional area of the protrusion relative to the cross-sectional area of at least one of the plurality of protrusions is formed in the range of 1 to 0.04 or more and 1 to 0.12 or less. There is an advantage that the luminance can be made uniform while improving the transmittance and the light diffusion.

Although not shown in the present embodiment, a protective sheet may be included.

The diffusion plate 580 may be disposed between the light source 520 and the optical sheet 530, and may diffuse light incident from the light source 520 upward. This is to prevent the shape of the light source 520 from being visible through the backlight unit 500 and to further diffuse the light.

Therefore, the backlight unit including the optical sheet according to the first embodiment of the present invention operates as follows.

Light generated from the light source is incident on the optical sheet. A part of the light incident on the optical sheet collides with the first diffusion particles of the protrusion to change the path, and the other part of the light passes through the exit surface of the first diffusion part to the liquid crystal panel.

The light whose path is changed by hitting the first diffuser is hit by another adjacent first diffuser and the path is changed again, and some of them are propagated to the liquid crystal panel through the exit surface of the first diffuser, and some of the other first diffuser are The path is changed again.

Finally, the light passing through the exit surface of the first diffusion part is incident evenly onto the liquid crystal panel.

As a result, the light incident on the optical sheet is reflected by the plurality of first diffusion particles formed in the protrusion part and diffuses while changing its propagation path, thereby improving luminance uniformity.

8A and 8B illustrate a configuration of a liquid crystal display according to an exemplary embodiment of the present invention.

8A and 8B illustrate the backlight unit shown in FIGS. 6A and 6B as the backlight unit, but the present invention is not limited thereto, and the backlight unit illustrated in FIGS. 7A and 7B may be employed as the backlight unit. . Meanwhile, since the backlight units illustrated in FIGS. 8A and 8B are the same as described above, overlapping descriptions are omitted and only the features thereof will be described.

8A and 8B, the liquid crystal display 600 according to an exemplary embodiment may display an image by using the electro-optical characteristics of the liquid crystal.

The LCD 600 may include a backlight unit 610 and a liquid crystal panel 710.

The backlight unit 610 may be mounted under the liquid crystal panel 710 and may provide light to the liquid crystal panel 710.

The backlight unit 610 may include a light source 620 and an optical sheet 630. In addition, the backlight unit 610 may further include a light guide plate 640, a reflector 650, a bottom cover 660, and a mold frame 670.

The liquid crystal panel 710 may be seated on the mold frame 670 and may be fixed by the top cover 720 fastened to the bottom cover 660 in a top-down manner.

The liquid crystal panel 710 may display an image using light provided from the backlight unit 610, specifically, light emitted from the light source 620.

The liquid crystal panel 710 may include a color filter substrate 712 and a thin film transistor substrate 714 facing each other with the liquid crystal interposed therebetween.

The color filter substrate 712 may implement colors of the image displayed through the liquid crystal panel 710.

The color filter substrate 712 may include a color filter array formed of a thin film on a transparent substrate such as glass or plastic, for example, a red / green / blue color filter. Here, the upper polarizer may be disposed on the color filter substrate 712.

The thin film transistor substrate 714 is electrically connected to the printed circuit board 618 on which a plurality of circuit components are mounted through the driving film 616. The thin film transistor substrate 714 may apply a driving voltage provided from the printed circuit board 618 to the liquid crystal in response to a driving signal provided from the printed circuit board 618.

The thin film transistor substrate 714 may include a thin film transistor and a pixel electrode formed of a thin film on another substrate of a transparent material such as glass or plastic.

Here, a lower polarizer may be attached to the lower portion of the thin film transistor substrate 714.

As such, the optical sheet, the backlight unit including the same, and the liquid crystal display according to the exemplary embodiments may include first diffusion particles formed in the cross-sectional area of the protrusion relative to the cross-sectional area of at least one of the plurality of protrusions in the optical sheet. Since the total cross-sectional area of is formed in one to 0.04 or more and one to 0.12 or less, there is an advantage that the luminance can be made uniform while improving the light transmittance and the light diffusivity.

In addition, the optical sheet, the backlight unit and the liquid crystal display including the same according to the embodiments of the present invention further include a protective layer under the optical sheet, thereby improving the heat resistance and mechanical strength of the optical sheet.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the above-described technical configuration of the present invention may be embodied in other specific forms by those skilled in the art to which the present invention pertains without changing its technical spirit or essential features. It will be appreciated that it may be practiced.

Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. Also, it is to be construed that all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention.

1A and 1B illustrate an optical sheet according to a first embodiment of the present invention.

2 is a cross-sectional view of an optical sheet according to a first embodiment of the present invention.

3 is for explaining the cumulative volume of the first diffusion particles according to the first embodiment of the present invention.

4 is for explaining various examples of the protrusion according to the first embodiment of the present invention.

5A to 5D illustrate the planar or side surfaces of the protrusions according to the first embodiment of the present invention.

6A and 6B illustrate the configuration of a backlight unit including an optical sheet according to example embodiments.

7A and 7B illustrate a configuration of a backlight unit including an optical sheet according to another exemplary embodiment of the present disclosure.

8A and 8B illustrate a configuration of a liquid crystal display according to an exemplary embodiment of the present invention.

Claims (18)

materials; Located on the substrate, a projection comprising a plurality of acids and a plurality of first diffusion particles, including; The total cross-sectional area of the first diffusion particles formed in the cross-sectional area of the protrusion relative to the cross-sectional area of the protrusion of at least one of the cross-sectional area of the protrusion perpendicular to the longitudinal direction of the acid is 1 to 0.04 or more, 1 to 0.12 or less Sheet. According to claim 1, In the plurality of first diffusion particles, the diameter of the first diffusion particles corresponding to the cumulative volume of 50% with respect to 100% of the cumulative volume of the first diffusion particles is X µm, and X-1.5 µm or more and X + 1.5 µm or less. The cumulative volume of the first diffused particles having a diameter in the range of 40% or more and 80% or less compared to the cumulative volume of the entire first diffused particles. The method of claim 1, The diameters of the plurality of first diffusion particles are 1 µm or more and 10 µm or less. The method of claim 1, The said X is 1 micrometer or more and 4 micrometers or less, The optical sheet characterized by the above-mentioned. The method of claim 1, And the plurality of first diffusion particles are beads. According to claim 1, The plurality of first diffusion particles are at least one or two or more of polymethyl methacrylate (PMMA), polystyrene, and silicon. According to claim 1, The substrate is at least one or two or more of polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP), polyethylene (PE), polystyrene and polyepoxy. According to claim 1, The protrusions are optical sheets, characterized in that each made of a different width. According to claim 1, The protrusion is an optical sheet, characterized in that made of different heights. According to claim 1, The protruding portion forms continuous bends having different heights, and the left and right amplitudes vary randomly. According to claim 1, The optical sheet further comprises a primer layer between the substrate and the protrusion. The method of claim 11, wherein The primer layer is at least one or two or more of acrylic, ester and urethane-based optical sheet. The method of claim 11, wherein The thickness of the said primer layer is 5 nm or more and 300 nm or less, The optical sheet characterized by the above-mentioned. According to claim 1, The optical sheet further comprises a protective layer under the substrate. The method of claim 14, The protective layer comprises a base material and a plurality of second diffusion particles. The method of claim 15, The diameter of the second diffusion particles is 1 µm or more and 10 µm or less. A backlight unit comprising the light source sheet according to any one of claims 1 to 16. A liquid crystal display device comprising the light source sheet according to any one of claims 1 to 16.

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