KR102174681B1 - Liquid crystal display device and method for manufacturing of liquid crystal display device - Google Patents

Abstract

The present specification is a backlight unit; And an optical sheet attached to one surface of the backlight unit, wherein the optical sheet includes a pattern layer and a low refractive index layer, the difference in refractive index between the pattern layer and the low refractive layer is 0.02 to 0.2, and the pattern layer is a flat surface A first surface comprising a; And a second surface facing the first surface and including a plurality of protrusions, wherein the low refractive index layer is provided on a first surface or a side of the second surface.

Description

Liquid crystal display device and manufacturing method of liquid crystal display device {LIQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR MANUFACTURING OF LIQUID CRYSTAL DISPLAY DEVICE}

The present specification relates to a liquid crystal display device and a method of manufacturing the same.

Liquid crystal display devices are widely used from mobile phones and portable small electronic devices to large electronic devices such as personal computers and televisions, and their use is one of the flat panel displays that is gradually expanding.

As the use of the display device expands, the place where the display device is placed and its location are diversified, but there is a problem in that a flat display cannot obtain a clear image when viewed from a direction other than the front of the display. In particular, in the case of a vehicle display, since the position of the display and the driver's gaze are not parallel, there is a problem that a clear image cannot be obtained from the driver's field of view.

Therefore, in order to solve such a problem, development of a display device capable of improving a viewing angle and a contrast ratio is required.

Registered Patent Publication No. 10-1210985

An object of the present specification is to provide a liquid crystal display device with improved contrast ratio and improved viewing angle, and a method of manufacturing the same.

The present invention is a backlight unit; And an optical sheet attached to one surface of the backlight unit, wherein the optical sheet includes a pattern layer and a low refractive index layer, the difference in refractive index between the pattern layer and the low refractive layer is 0.02 to 0.2, and the pattern layer is a flat surface A first surface comprising a; And a second surface facing the first surface and including a plurality of protrusions, wherein the low refractive index layer is provided on the first surface or the second surface.

In addition, the present invention comprises the steps of preparing a substrate; Forming an optical sheet on the substrate, wherein the optical sheet includes a pattern layer and a low refractive index layer, the difference in refractive index between the pattern layer and the low refractive layer is 0.02 to 0.2, and the pattern layer has a flat surface. A first side comprising; And a second surface facing the first surface and including a plurality of protrusions, and a method of manufacturing a liquid crystal display including a low refractive index layer provided on the first surface or the second surface side.

Finally, the present invention comprises the steps of preparing a substrate; Forming an optical sheet on the substrate, wherein the optical sheet includes a pattern layer and a low refractive index layer, the difference in refractive index between the pattern layer and the low refractive layer is 0.02 to 0.2, and the pattern layer has a flat surface. A first side comprising; And a second surface facing the first surface and including a plurality of protrusions, and a low refractive index layer provided on the first surface or the second surface side, wherein the forming of the optical sheet is It provides a method of manufacturing a liquid crystal display device formed by a printing method.

The liquid crystal display device of the present invention comprises: a backlight unit; And an optical sheet attached to one surface of the backlight unit, wherein the optical sheet includes a pattern layer and a low refractive index layer, wherein a difference in refractive index between the pattern layer and the low refractive layer is 0.02 to 0.2, and the pattern layer is a flat surface A first surface comprising a; And a pattern layer including a second surface facing the first surface, and the second surface including a plurality of protrusions, thereby improving contrast ratio and improving viewing angle, and obtaining a liquid crystal display device having excellent durability. I can.

1 and 2 are diagrams illustrating liquid crystal display devices 100 and 200 according to an exemplary embodiment of the present invention.
3 to 8 are diagrams showing experimental results of Comparative Examples 1 to 4 and Examples 1 and 2, respectively.

Hereinafter, preferred embodiments of the present invention will be described. However, the embodiments of the present invention may be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided to explain the present invention in more detail to a person having average knowledge in the art.

A liquid crystal display according to an embodiment of the present invention includes a backlight unit; And an optical sheet attached to one surface of the backlight unit, wherein the optical sheet includes a pattern layer and a low refractive index layer, the difference in refractive index between the pattern layer and the low refractive layer is 0.02 to 0.2, and the pattern layer is a flat surface A first surface comprising a; And a second surface facing the first surface and including a plurality of protrusions, and a low refractive index layer provided on the first surface or the second surface side.

According to an exemplary embodiment of the present invention, when the liquid crystal display device is applied to a vehicle display, a clear image can be obtained in the driver's field of view by improving the viewing angle and improving the contrast ratio.

According to an exemplary embodiment of the present invention, each of the protrusions includes a first inclined surface and a second inclined surface, and an angle θ formed by the first inclined surface and the second inclined surface is 20° to 60°.

According to an embodiment of the present invention, processing is not possible when the angle θ formed by the first and second inclined surfaces is less than 20°, and when it exceeds 60°, light refracted through the pattern layer is condensed. Therefore, as in the present invention, the contrast ratio improvement effect cannot be obtained.

The term "inclined surface" refers to a surface that is inclined by more than 0° and less than 90° or perpendicular to a horizontal surface or a first surface including the flat surface.

In addition, the "inclined surface" means a plane, but is not limited thereto.

The angle θ formed between the first inclined surface and the second inclined surface means an angle formed by the first inclined surface and the second inclined surface when the first inclined surface and the second inclined surface are in contact, and the first inclined surface and the second inclined surface are When not in contact, it means an angle formed by a line extending the first inclined surface and the second inclined surface.

The angle θ formed between the first and second inclined surfaces may be 20° to 60°, and according to another example, it may be 30° to 50° and 40° to 50°. When the angle θ formed by the first inclined surface and the second inclined surface satisfies the above range, the refraction angle of light incident on the optical sheet can be adjusted, so that the viewing angle of the liquid crystal display device manufactured including the optical sheet can be adjusted. .

According to another embodiment, the plurality of protrusions may be provided not to be continuous.

According to an embodiment of the present invention, at least one cross section perpendicular to the first surface of the pattern layer may have a triangular shape or a square shape.

When at least one cross-section perpendicular to the first surface has a triangular shape, ends of the first and second inclined surfaces are positioned to abut the first surface. At this time, the angle between the first inclined surface and the first surface is θ ₁ , the angle between the second inclined surface and the first surface is θ ₂ , and the angle (θ ₁ ) between the first inclined surface and the first surface is It is preferable that the angle θ ₂ formed between the second inclined surface and the first surface have different angles. As the angle θ ₁ formed by the first inclined surface and the first surface and the angle θ ₂ formed by the second inclined surface and the first surface have different values, the refraction angle of light incident on the pattern layer may be adjusted.

When at least one cross-section perpendicular to the first surface has a quadrangular shape, a first inclined surface formed to abut the first surface and an end portion, a third inclined surface formed to abut the first inclined surface, and And a second inclined surface positioned to abut the end. At this time, the angle between the first inclined surface and the first surface is θ ₁ , the angle between the second inclined surface and the first surface is θ ₂ , and the angle (θ ₁ ) between the first inclined surface and the first surface is It is preferable that the angle θ ₂ formed between the second inclined surface and the first surface have different angles. As the angle θ ₁ formed by the first inclined surface and the first surface and the angle θ ₂ formed by the second inclined surface and the first surface have different values, the refraction angle of light incident on the pattern layer may be adjusted.

According to another exemplary embodiment, a plurality of protrusions of the pattern layer may be disposed in succession. When the plurality of protrusions are continuously provided, the pattern layer is formed so that the first inclined surface of one protrusion and the second inclined surface or the third inclined surface of the other protrusion abut.

The height (h) of the pattern layer is a vertical distance between the first surface and the protrusion, or when the protrusion includes the first inclined surface to the third inclined surface, one of the vertical distance between the first surface and the first inclined surface to the third inclined surface It means a distance having a possible long value, and the height h of the pattern layer may be 1 to 500 μm.

The refractive angle of light passing through the pattern layer of the optical sheet may be 1° to 20°. According to another embodiment, it may be 3° to 15°.

The material of the pattern layer may be an ultraviolet curable resin, but is not limited thereto. As an example of the ultraviolet curable resin, epoxy (meth) acrylate, urethane (meth) acrylate, phenylphenol ethoxylated (meth) acrylate, trimethylolpropane ethoxylated (meth) acrylate, phenoxy Benzyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, ethoxylated thiodiphenyldi (meth)acrylate, phenylthioethyl (meth)acrylate monomers or oligomers thereof, or fluorene derivatives unsaturated It may include a resin, but is not limited thereto.

In one embodiment of the present invention, the liquid crystal display device includes a low refractive index layer provided on the first side or the second side of the pattern layer. The low refractive layer may be formed using an ultraviolet curable resin or an acrylate adhesive. The low refractive layer may be a Soken's LC-435 product, but is not limited thereto.

The thickness of the low refractive layer may be the pattern layer height *X, and X means 1 to 50. The thickness of the low refractive layer may be 1 to 200 μm.

According to an exemplary embodiment of the present invention, it may further include forming one or more optical layers on the low refractive index layer. The optical layer may be an anti-glare layer (AG), a hard coating layer (HC), a low refractive index layer (LR), an anti-glare & low-reflection (AGLR), an anti-reflection layer (AR), and the like, but is not limited thereto.

The hard coating layer, anti-glare layer (AG), low refractive index layer (LR), AGLR (Anti-Glare & Low-Reflection), and anti-reflection layer (AR) may be formed of a material of a common primer layer, and the hard coating layer , The anti-glare layer (AG), the low refractive index layer (LR), the AGLR (Anti-Glare & Low-Reflection), or the anti-reflection layer (AR) may each have a thickness of 1 to 100 μm.

In an exemplary embodiment of the present invention, the difference between the refractive index of the low refractive index layer and the pattern layer may be 0.02 to 0.2, preferably 0.03 to 0.2. When the difference between the refractive index of the pattern layer and the refractive index of the low refractive layer has the above value, a viewing angle of a liquid crystal display device including the optical sheet may be improved by adjusting a refractive angle at which light incident on the pattern layer is emitted. The method of measuring the difference in refractive index between the pattern layer and the low refractive layer is to laminate the backlight unit including the optical sheet to a liquid crystal display device, and then drive white using Eldim's EZcontrast to determine the angle of the region where the intensity of light is strongest. It can be confirmed by measuring the tilt of the light.

The refractive index of the low refractive layer may be 1.4 to 1.6, specifically 1.4 to 1.5, more specifically 1.46 to 1.48, and when the above range is satisfied, an appropriate viewing angle and business card ratio can be obtained when applied to a display device.

The refractive index of the pattern layer may be 1.5 to 1.7. When the above range is satisfied, an appropriate viewing angle and business card ratio can be obtained when applied to a display device.

A film may be further included on one surface of the optical sheet. When a film is further included on one surface of the optical sheet as described above, the optical sheet may be laminated in the order of film/pattern layer/low refractive layer or film/low refractive layer/pattern layer.

At this time, the film is polyester, polyacrylic, polyvinyl chloride, polycarbonate, polymethylmethacrylate, polystyrene, polyester sulfone, polybutadiene, triacetate cellulose film (TAC), cycloolefin polymer (COP), polyethylene tere It may be a phthalate (PET) or an acrylic film, but is not limited thereto.

The acrylic film may include a (meth)acrylate-based resin, and a film containing a (meth)acrylate-based resin is formed by extrusion molding a molding material containing a (meth)acrylate-based resin as a main component. Can be obtained.

The acrylic film is a film including a copolymer including an alkyl (meth) acrylate unit and a styrene unit and an aromatic resin having a carbonate moiety in the main chain, or an alkyl (meth) acrylate unit, a styrene unit, at least It may be a film including a 3 to 6 elemental heterocyclic unit and a vinyl cyanide unit substituted with one carbonyl group. In addition, it may be an acrylic resin having a lactone structure.

Specific examples of the (meth)acrylate-based resin having a lactone ring structure include, for example, lactones described in Japanese Laid-Open Patent Publication No. 2000-230016, Japanese Laid-Open Patent Publication No. 2001-151814, Japanese Laid-Open Patent Publication No. 2002-120326, etc. And (meth)acrylate-based resins having a cyclic structure.

Examples of the (meth)acrylate-based resin having an aromatic ring include (a) a (meth)acrylate-based unit containing one or more (meth)acrylate-based derivatives described in Korean Patent Application Laid-Open No. 10-2009-0115040; (b) an aromatic unit having a chain having a hydroxy group-containing moiety and an aromatic moiety; And (c) a resin composition comprising a styrene-based unit containing at least one styrene-based derivative. Each of the (a) to (c) units may be included in the resin composition in the form of separate copolymers, and two or more units of the (a) to (c) units may be included in the resin composition in the form of one copolymer. have.

The method for producing the (meth)acrylate-based resin film is not particularly limited, and for example, the (meth)acrylate-based resin and other polymers, additives, and the like are sufficiently mixed by any appropriate mixing method to prepare a thermoplastic resin composition. After production, it may be prepared by film-forming it, or (meth) acrylate-based resin and other polymers, additives, and the like may be prepared as a separate solution and then mixed to form a uniform mixture, and then film-molded.

The thermoplastic resin composition is prepared by extruding and kneading the obtained mixture after pre-blending the film raw material with any suitable mixer such as an omni mixer. In this case, the mixer used for extrusion and kneading is not particularly limited, and for example, any suitable mixer such as an extruder such as a single screw extruder and a twin screw extruder or a pressure kneader can be used.

The film forming method may include any suitable film forming method such as a solution cast method (solution casting method), a melt extrusion method, a calender method, and a compression molding method, but is not limited thereto, but a solution casting method (solution casting method) , A melt extrusion method is preferred.

The solvent used in the solution casting method (solution casting method) includes, for example, aromatic hydrocarbons such as benzene, toluene, and xylene; Aliphatic hydrocarbons such as cyclohexane and decalin; Esters such as ethyl acetate and butyl acetate; Ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; Alcohols such as methanol, ethanol, isopropanol, butanol, isobutanol, methyl cellosolve, ethyl cellosolve, and butyl cellosolve; Ethers such as tetrahydrofuran and dioxane; Halogenated hydrocarbons such as dichloromethane, chloroform, and carbon tetrachloride; Dimethylformamide; Dimethyl sulfoxide and the like can be mentioned, and these solvents may be used alone or in combination of two or more.

An apparatus for performing the solution casting method (solution casting method) may include, for example, a drum type casting machine, a band type casting machine, a spin coater, and the like. Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature is specifically 150 to 350°C, more specifically 200 to 300°C, but is not limited thereto.

In the case of forming a film by the T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, and the extruded film is wound into a film shape to obtain a roll-shaped film. At this time, uniaxial stretching may also be performed by appropriately adjusting the temperature of the take-up roll and stretching in the extrusion direction. Further, simultaneous biaxial stretching and sequential biaxial stretching may be performed by stretching the film in a direction perpendicular to the extrusion direction.

The acrylic film may be either an unstretched film or a stretched film. In the case of a stretched film, it may be a uniaxially stretched film or a biaxially stretched film, and in the case of a biaxially stretched film, it may be either a simultaneous biaxially stretched film or a sequential biaxially stretched film. In the case of biaxial stretching, mechanical strength is improved and film performance is improved. By mixing another thermoplastic resin, the acrylic film can suppress an increase in retardation even when stretching is performed, and can maintain optical isotropy.

The stretching temperature is preferably in a range near the glass transition temperature of the thermoplastic resin composition as a raw material for the film, preferably (glass transition temperature -30°C) to (glass transition temperature +100°C), more preferably (glass transition temperature). It is within the range of temperature -20℃) to (glass transition temperature +80℃). If the stretching temperature is less than (glass transition temperature -30°C), there is a concern that sufficient stretching ratio cannot be obtained. Conversely, when the stretching temperature exceeds (glass transition temperature +100°C), flow (flow) of the resin composition occurs, and there is a fear that stable stretching may not be performed.

The draw ratio defined by the area ratio is preferably 1.1 to 25 times, more preferably 1.3 to 10 times. If the draw ratio is less than 1.1 times, there is a fear that it may not lead to improvement in toughness accompanying the stretching. When the draw ratio exceeds 25 times, there is a fear that the effect of increasing the draw ratio is not recognized.

The stretching speed is preferably 10 to 20,000%/min, more preferably 100 to 10.000%/min in one direction. When the drawing speed is less than 10%/min, it takes a little longer time to obtain a sufficient draw ratio, and there is a fear that the manufacturing cost may increase. If the stretching speed exceeds 20,000%/min, there is a concern that the stretched film may break.

The acrylic film may be subjected to heat treatment (annealing) or the like after stretching treatment in order to stabilize its optical isotropy or mechanical properties. The heat treatment conditions are not particularly limited, and any suitable conditions known in the art may be employed.

According to an exemplary embodiment of the present invention, an anti-glare layer (AG), a hard coating layer (HC), a low refractive index layer (LR), an anti-glare & low-reflection (AGLR), and an anti-reflection layer (AR) are provided on at least one surface of the film. ) And the like may be formed. At this time, by using the coating composition for forming the layers, the coating composition is applied onto the base film using a method well known in the art, for example, a bar coating method, a gravure coating method, a slot die coating method, etc. It can be applied to and dried by a method. At this time, the drying may be performed through a convention oven, but is not limited thereto, and is preferably performed at a temperature of 100°C to 120°C for 1 minute to 5 minutes. The drying temperature varies depending on the coating step, and in the case of a film that has been stretched, it may be performed within a range that does not exceed the glass transition temperature (Tg) of the film, and if it includes stretching, drying is performed at the stretching temperature at the same time as the stretching. It is carried out within a range not exceeding the decomposition temperature (Td) of.

According to an exemplary embodiment of the present invention, a method of manufacturing the liquid crystal display device includes: preparing a substrate; Forming an optical sheet on the substrate, wherein the optical sheet includes a pattern layer and a low refractive index layer, and the pattern layer includes a first surface including a flat surface; And a second surface facing the first surface and including a plurality of protrusions, and a low refractive index layer provided on the first surface or the second surface side.

The forming of the optical sheet may include forming any one of a pattern layer and a low refractive index layer on a substrate; And forming the other layer of the pattern layer and the low refractive layer.

According to another exemplary embodiment, the step of forming the optical sheet may be formed by an imprinting method, but is not limited thereto. In the imprinting method, a coating composition for forming a pattern layer or a low refractive index layer is applied to a mold or a substrate using a Pre Gap Roll, and UV irradiated at the moment or immediately after the rotating mold and the substrate moving along the mold are in contact. It is formed by carrying out primary curing and/or secondary curing.

The substrate may be LCF (3M, Louver Film), DBEF (Double Bright Enhancement Film), PET film (polyethylene terephthalate film), but is not limited thereto.

The coating composition may further include an initiator. The initiator may be included in an amount of 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the UV-curable resin.

The initiator may be ketone-based, phosphine oxide-based, triazine-based, acetophenone-based, benzophenone-based, and the like, but is not limited thereto.

The coating composition may further include a solvent, and the solvent may be alcohol-based, ketone-based, ether-based, hexane-based, or benzene-based. More specifically, the solvent is methanol, ethanol, isopropanol, 2-methoxyethanol, butanol, isooctanol, methyl cellulose, ethyl sorb sorb, isopropyl cellulose, butyl cellulose, methyl carbitol, ethyl carbitol, Isopropyl carbitol, butyl carbitol, acetone, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, dibutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, hexane , Heptane, octane, benzene, toluene, and may be at least one member selected from the group consisting of xylene, but is not limited thereto.

The coating composition may further include an antioxidant, a UV absorber, a light stabilizer, a leveling agent, a surfactant, a lubricant, etc. as an additive, and may be included in an amount of 0.001 to 5 parts by weight based on the total amount of the coating composition.

The UV irradiation amount of the first and second curing in the step of forming the pattern layer is about 0.01 to 2 J/cm ² , preferably 0.1 to 1 J/cm ² , and more preferably 0.2 to 0.5 J/cm ² to be.

1 and 2 show the liquid crystal display devices 100 and 200 according to the present embodiment, and the liquid crystal display device 100 of FIG. 1 includes a light source 1, a reflective sheet 2, a light guide plate 3, and a diffusion sheet. (4), a prism sheet 5 and an optical sheet 6 are included. The liquid crystal display device 200 of FIG. 2 includes a light source 1, a reflective sheet 2, a light guide plate 3, a bottom diffusion sheet 1 (4-1), a prism sheet 1 (5-1), and a prism sheet 2 (5). -2), the top diffusion sheet 2 (4-2) and the optical sheet (6).

The light source 1 irradiates light and may be disposed on the side of the light guide plate 3. The kind of the light source is not particularly limited, and a general LCD light source such as CCFL, HCFL or LED may be used.

The reflective sheet 2 is formed on the lower surface of the light guide plate 3 to internally reflect and emit light incident from the light source 1.

The light guide plate 3 serves to internally reflect and emit light incident from a light source.

As the main viewing angle (maximum brightness angle) of the liquid crystal display device changes and the light concentration increases, a contrast ratio (C/R) at a position not parallel to the liquid crystal display device may be improved.

The backlight unit includes a light source that irradiates light from the rear surface of the liquid crystal panel, and the type of the light source is not particularly limited, and a general LCD light source such as CCFL, HCFL, or LED may be used.

Hereinafter, the functions and effects of the invention will be described in more detail through specific embodiments of the invention. However, these embodiments are only presented as examples of the invention, and the scope of the invention is not determined thereby.

< Experimental example >

Comparative example One.

Using the Zemax program, the light distribution simulation of the backlight unit stacked in the order of reflective sheet/light guide plate/diffusion sheet/prism sheet was performed, and the measurement conditions were operated with 10 million rays. The graph measured in the simulation (white mode) is shown in FIG. 3.

Comparative example 2.

In Comparative Example 1, a pattern layer and a low refractive index layer were included on one side of the backlight unit, and an optical sheet having a difference in refractive index between the pattern layer and the low refractive index layer was attached. Proceeded. The graph measured in the simulation (white mode) is shown in FIG. 4.

Comparative example 3.

In Comparative Example 1, a pattern layer and a low refractive index layer were included on one surface of the backlight unit, and an optical sheet having a difference in refractive index between the pattern layer and the low refractive index layer was attached. Proceeded. The graph measured in the simulation (white mode) is shown in FIG. 5.

Comparative example 4.

In Comparative Example 2, a simulation was conducted in the same manner as in Comparative Example 2, except that the low refractive layer was not included. The graph measured in the simulation (white mode) is shown in FIG. 6.

Example One.

In Comparative Example 1, a pattern layer and a low refractive index layer were included on one surface of the backlight unit, and an optical sheet having a refractive index difference of 0.06 between the pattern layer and the low refractive index layer was attached. Proceeded. The graph measured in the simulation (white mode) is shown in FIG. 7.

Example 2.

In Comparative Example 1, a pattern layer and a low refractive index layer were included on one surface of the backlight unit, and an optical sheet having a refractive index difference of 0.09 between the pattern layer and the low refractive index layer was attached. Proceeded. A graph measured in the simulation (white mode) is shown in FIG. 8.

The simulation measurement results of Comparative Examples 1 to 4, Examples 1 and 2 are shown in Table 1 below, respectively. In Table 1 below, the simulation measurement results of Comparative Examples 2 to 4, Example 1, and Example 2 are values expressed based on the measured values of Comparative Example 1. Specifically, the viewing angle luminance value of Theta 40/Phi 174 of Comparative Example 2 indicates a value of 97% when the viewing angle luminance value of Theta 40/Phi 174 of Comparative Example 1 is 100.

In Table 1, Phi means angles 0 to 360 obtained by proceeding counterclockwise based on 0 in the graph measured in the experiment, and Theta is a circle located outside with the center of the graph measured in the experiment as 0 ( Or, the value increases by 10 as the value increases.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Viewing angle Theta Phi 40 174 100% 97% 24% 10% 88% 79% 44 209 100% 101% 175% 75% 131% 148% face 0 0 100% 98% 58% 15% 95% 94%

Comparing Comparative Examples 1 and 2 with Examples 1 and 2, Examples 1 and 2 of the present invention slightly decreased the viewing angle luminance and front luminance in Theta 40/Phi 174 than Comparative Examples 1 and 2, but Theta It can be seen that the viewing angle luminance at 44/Phi 209 increased by 31% and 48%, respectively, and the viewing angle range was greatly improved.

In addition, comparing the Comparative Examples 3 and 4 with Examples 1 and 2, Comparative Example 3 significantly reduced the viewing angle luminance in Theta 40/Phi 174 than in Examples 1 and 2 of the present application, and Theta 44/Phi 209 Although the viewing angle luminance in was significantly increased, it was difficult to secure the viewing angle and contrast ratio, because the front luminance had a very low value. It can be seen that the luminance value is very low, and it is difficult to secure the viewing angle and contrast ratio.

100, 200: liquid crystal display
1: light source
2: reflective sheet
3: light guide plate
4: diffusion sheet
4-1: Bottom diffusion sheet 1
4-2: Top diffusion sheet
5: prism sheet
5-1: Prism sheet 1
5-2: Prism sheet 2
6: optical sheet

Claims (9)

Backlight unit; And an optical sheet attached to one surface of the backlight unit,
The optical sheet includes a pattern layer and a low refractive layer,
The difference in refractive index between the pattern layer and the low refractive layer is 0.02 to 0.2,
The pattern layer includes a first surface including a flat surface; And a second surface facing the first surface and including a plurality of protrusions,
The low refractive index layer is provided on the first surface or the second surface side,
Each of the protrusions includes a first inclined surface and a second inclined surface, and an angle θ formed by the first and second inclined surfaces is 20° to 60°. delete The method of claim 1,
Ends of the first and second inclined surfaces are in contact with the first surface. The method of claim 3,
The liquid crystal display device having an angle θ ₁ formed between the first inclined surface and the first surface and an angle θ ₂ formed between the second inclined surface and the first surface have different angles. The method of claim 1,
The plurality of protrusions are arranged in succession. The method of claim 1,
A liquid crystal display device in which at least one cross section perpendicular to the first surface of the pattern layer has a triangular or rectangular shape. Preparing a substrate;
Including the step of forming an optical sheet on the substrate,
The optical sheet includes a pattern layer and a low refractive layer,
The difference in refractive index between the pattern layer and the low refractive layer is 0.02 to 0.2,
The pattern layer includes a first surface including a flat surface; And a second surface facing the first surface and including a plurality of protrusions,
It includes a low refractive index layer provided on the first surface or the second surface side,
Each of the protrusions includes a first inclined surface and a second inclined surface, and an angle θ formed by the first and second inclined surfaces is 20° to 60°. The method of claim 7,
The forming of the optical sheet may include forming one of a pattern layer and a low refractive index layer on a substrate; And forming the other layer of the pattern layer and the low refractive layer. The method of claim 7,
The step of forming the optical sheet is a method of manufacturing a liquid crystal display device formed by an imprinting method.

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