KR102513845B1 - Optical film and liquid crystal display - Google Patents

Abstract

This application relates to an optical film and a liquid crystal display including the same. In the present application, by applying an optical film having a specific structure, by selectively adjusting the reflection of light that causes color washout in both vertical and horizontal directions, the luminance uniformity and contrast ratio of the emitted light can be improved. A liquid crystal display can be provided.

Description

Optical film and liquid crystal display {Optical film and liquid crystal display}

The present invention relates to optical films and liquid crystal displays.

A liquid crystal display (LCD: Liquid Crystal Display) is a display device utilizing the anisotropy of a liquid crystal. A liquid crystal display generally has a structure having a liquid crystal panel including a liquid crystal layer having a liquid crystal material and polarizers disposed on both sides thereof, and implements a black and white state by changing the alignment of the liquid crystal layer and displays an image.

Since a liquid crystal panel generally adjusts polarization to light incident perpendicularly to the panel, a problem occurs in that the brightness or color of the light changes with respect to light from an oblique direction.

In order to solve such a problem, a method of arranging a so-called optical compensation film or the like on the viewing side of a liquid crystal panel is known, as in the case of Patent Literature 1, for example.

Meanwhile, the liquid crystal display has various modes depending on the orientation of liquid crystals in the liquid crystal panel, and representatively, there are twisted nematic (TN), vertical alignment (VA), or in plane switching (IPS) modes.

Among the modes, the VA mode generally has an excellent contrast ratio and excellent color reproduction, but a color washout phenomenon in which the gamma value changes occurs when the display is observed from an inclined angle compared to the case of observing the display from the front direction. .

In addition, in the case of the TN mode, the price is low and the response speed is excellent, but similar to the VA mode, a phenomenon in which the gamma value changes occurs when viewing the display from an inclined angle compared to the case of observing the display from the front direction.

Korean Patent Publication No. 2009-0080133

The present application provides an optical film and a liquid crystal display including the optical film. The present application is directed to mitigating the color washout phenomenon occurring in liquid crystal displays, particularly VA (Vertically Aligned) mode or TN (Twisted Nematic) mode liquid crystal displays in both vertical and horizontal directions, and improving the contrast ratio at the same time. for one purpose

This application relates to an optical film. 1 and 2 each exemplarily shows the optical film of the present application. 1 is a front side of the optical film and FIG. 2 is a side view of the optical film. The optical film of the present application may include a first region 10 and a second region 20 having different refractive indices, and a third region 30 between the first region and the second region. The first region and the third region may be divided by a first boundary surface composed of a plurality of inclined surfaces. The second area and the third area may be divided by a second boundary surface composed of a plurality of inclined surfaces.

FIG. 3 illustrates a second boundary surface dividing the second region 20 and the third region 30 by way of an example of a boundary surface composed of a plurality of inclined surfaces s1, s2, s3, s4, ..., and sn. The first inclined plane dividing the first region 10 and the third region 30 may also have the same structure as in FIG. 3 .

In this application, the refractive index n1 of the first region, the refractive index n2 of the second region, the refractive index n3 of the third region, and the angle formed by two adjacent slopes at the first or second boundary surface (α, Adjusting the relationship between α ₁ and α ₂ ) can be considered as one technical feature when distinction is needed. In this specification, the inclination angle of the boundary surface may mean the above angle. As shown in FIG. 4 , since the light at an angle (Θ ₁ ) at which discoloration does not occur can be spread through the optical film to an angle (Θ2 ) at which discoloration occurs using total reflection, the decolorization phenomenon can be slowed down. While describing the refractive index in this specification, it means the refractive index for a wavelength of 550 nm unless otherwise specified.

In the optical film of the present application, the first region may have a higher refractive index than the second region, and the third region may have a lower refractive index than the first region and a higher refractive index than the second region. That is, the refractive index (n1) of the first region, the refractive index (n2) of the second region, and the refractive index (n3) of the third region may satisfy the relationship n1 > n3 > n2. This refractive index relationship may be equally applied to the relationships of Equations 1 to 6 below. When the optical film is applied to the liquid crystal panel, among the first area, the second area, and the third area, the first area may be disposed closest to the liquid crystal panel.

In one example, in the optical film of the present application, the first combination of the refractive index of the first region (n ₁ ), the refractive index of the third region (n ₃ ) and the inclination angle of the first interface (α ₁ ), and the third region The second combination of the refractive index (n ₃ ) of the second area, the refractive index (n ₂ ) of the second region, and the inclination angle (α ₂ ) of the second interface may satisfy Equation 1 below.

[Equation 1]

In Equation 1, n _A means n ₁ in the first combination and n ₃ in the second combination, n _B means n ₃ in the first combination and n 2 in the second combination, and α means n ₂ in the first combination. α ₁ means α ₂ in the second combination.

When the optical film satisfies Equation 1, light incident in directions other than the vertical direction among light incident on the optical film due to the difference between the refractive index of the adjacent high and low refractive index areas and the angle formed by the inclined plane is as vertical as possible. The contrast ratio can be improved by not going in the direction.

In one example, in the optical film of the present application, the first combination of the refractive index of the first region (n ₁ ) and the inclination angle (α ₁ ) of the first boundary surface, the refractive index of the third region (n ₃ ) and the second boundary surface The second combination for the inclination angle α ₂ of may satisfy Equation 2 below.

[Equation 2]

In Equation 2, n _A means n ₁ in the first combination and n ₃ in the second combination, and α means α ₁ in the first combination and α ₂ in the second combination.

When the optical film satisfies Equation 2 above, light incident in directions other than the vertical direction among the light incident on the optical film due to the difference between the refractive index of the adjacent high and low refractive index areas and the angle formed by the inclined surface is as vertical as possible. The contrast ratio can be improved by not going in the direction.

In one example, in the optical film of the present application, the first combination of the refractive index of the first region (n ₁ ), the refractive index of the third region (n ₃ ) and the inclination angle of the first interface (α ₁ ), and the third region The second combination of the refractive index (n ₃ ) of the second region, the refractive index (n ₂ ) of the second region, and the inclination angle (α ₂ ) of the second interface may satisfy Equation 3 below.

[Formula 3]

In Equation 3, n _A means n ₁ in the first combination and n ₃ in the second combination, n _B means n ₃ in the first combination and n 2 in the second combination, and α means n ₂ in the first combination. α ₁ means α ₂ in the second combination.

When the optical film satisfies Equation 3 above, light incident in directions other than the vertical direction among the light incident on the optical film due to the difference between the refractive index of the adjacent high and low refractive index areas and the angle formed by the inclined surface is as vertical as possible. The contrast ratio can be improved by not going in the direction.

In one example, in the optical film of the present application, the first combination of the refractive index of the first region (n ₁ ), the refractive index of the third region (n ₃ ) and the inclination angle of the first interface (α ₁ ), and the third region The second combination of the refractive index (n ₃ ) of the second region, the refractive index (n ₂ ) of the second region, and the inclination angle (α ₂ ) of the second interface may satisfy Equation 4 below.

[Formula 4]

In Equation 4, n _A means n ₁ in the first combination and n ₃ in the second combination, n _B means n ₃ in the first combination and n 2 in the second combination, and α means n ₂ in the first combination. α ₁ means α ₂ in the second combination.

When the optical film satisfies Equation 4 above, light incident in directions other than the vertical direction among light incident on the optical film due to the difference between the refractive index of the adjacent high and low refractive index areas and the angle formed by the inclined surface is as vertical as possible. The contrast ratio can be improved by not going in the direction.

In one example, an inclination angle α ₁ of the first boundary surface and an inclination angle α ₂ of the second boundary surface may each independently range from 35 degrees to 70 degrees. In such an optical film, the first combination of the refractive index of the first region (n ₁ ) and the refractive index of the third region (n ₃ ), and the refractive index of the third region (n ₃ ) and the refractive index of the second region (n ₂ ) The second combination for each may satisfy Equation 5 below. An optical film that satisfies this requirement prevents light entering the optical film from directions other than the vertical direction from going in the vertical direction as much as possible due to the difference between the refractive index of the adjacent high and low refractive index areas and the angle formed by the inclined plane. Contrast can be improved by

[Formula 5]

In Equation 5, n _A means n ₁ in the first combination and n ₃ in the second combination, and n _B means n ₃ in the first combination and n ₂ in the second combination.

In one example, the inclination angle α ₁ of the first boundary surface and the inclination angle α ₂ of the second boundary surface may be each independently in the range of 70 degrees to 110 degrees. In such an optical film, a first combination of the refractive index of the first region (n ₁ ), the refractive index of the third region (n ₃ ) and the inclination angle of the first interface (α ₁ ), the refractive index of the third region (n ₃ ), The second combination of the refractive index (n ₂ ) of the second region and the inclination angle (α ₂ ) of the second interface may satisfy Equation 6 below. An optical film that satisfies this requirement prevents light entering the optical film from directions other than the vertical direction from going in the vertical direction as much as possible due to the difference between the refractive index of the adjacent high and low refractive index areas and the angle formed by the inclined plane. You can improve the contrast ratio by

[Formula 6]

In Equation 6, n _A means n ₁ in the first combination and n ₃ in the second combination, n _B means n ₃ in the first combination and n 2 in the second combination, and α means n ₂ in the first combination. α ₁ means α ₂ in the second combination.

In one example, the optical film of the present application may satisfy any one of Equations 1 to 6 above. In another example, the optical film of the present application may satisfy at least two or more of Equations 1 to 6 above. Specifically, the optical film of the present application may satisfy all of Equations 1 to 4 above. Such an optical film may be more advantageous in improving a contrast ratio while reducing discoloration in both vertical and horizontal directions.

In one example, the refractive index n1 of the first region may be within a range of about 1.50 to 1.67, and a known material having a refractive index within this range may be used without particular limitation. For example, materials used in the manufacture of so-called prism sheets in the industry and the like can be used. In addition, ultraviolet (UV) or thermosetting resins such as acrylate-based materials may be exemplified as known materials. For example, the above-described optical film may be manufactured by forming a layer having convex portions described below on a surface of the UV curable resin and then applying the above-described pressure-sensitive adhesive or adhesive to the surface.

In one example, the refractive index n2 of the second region may be in the range of about 1.39 to about 1.49. Various transparent materials having a refractive index in this range are known. The part of the optical film forming the second region may be, for example, a material having a refractive index within the above range among known optical pressure-sensitive adhesives or adhesives, for example, acrylic pressure-sensitive adhesives, etc., but is limited thereto. it is not going to be

In one example, the refractive index n3 of the third region may be appropriately adjusted to be smaller than the refractive index of the first region and greater than the refractive index of the second region.

In one example, angles α formed by two inclined surfaces adjacent to the first boundary surface or the second boundary surface may be the same as or different from each other. The standard deviation of the angle α may be in the range of 0 degrees to 5 degrees. The standard deviation may be about 5 degrees or less, about 4 or less, about 3 or less, about 2 or less, or about 1 or less in another example.

In one example, the first boundary surface may be surfaces of the first area and the third area itself. Accordingly, the first region and the third region may each have a surface corresponding to the first boundary surface. The surfaces of the first region and the third region may be in contact with each other. The second boundary surface may be the surface itself of the second region and the third region. Accordingly, the second area and the third area may each have a surface corresponding to the second boundary surface. The surfaces of the second region and the third region may be in contact with each other. In one example, an area formed by two inclined surfaces adjacent to the first or second boundary surface may be referred to as a convex portion of the first area, the second area, or the third area. The convex parts of the first region and the third region may have the same shape, and the convex parts of the second region and the third region may have the same shape.

In one example, the height of the convex portion of the first region, the second region, and/or the third region (H in FIG. 3 ) may be appropriately selected in consideration of the purpose of the present application. For example, the height of the convex portion may be in the range of 20 to 300 μm. In this case, since light at an angle at which discoloration does not occur can be spread to an angle at which discoloration occurs by using total reflection, discoloration can be reduced. The height may be 20 μm or more, 30 μm or more, or 40 μm or more in another example. In another example, the height may be 300 μm or less, 200 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, or 50 μm or less.

In one example, the convex parts of the first region, the second region, and/or the third region may be disposed apart from each other or disposed adjacent to each other. When the convex parts are spaced apart from each other, a region between the convex parts may be flat. The height of the flat region may be lower or higher than the height of the convex portion.

In one example, the pitch of the convex portions of the first region, the second region, and/or the third region (P in FIG. 3) may be appropriately selected in consideration of the purpose of the present application. For example, the pitch of the convex portions may be 10 to 50 μm. In this case, since light at an angle at which discoloration does not occur can be spread to an angle at which discoloration occurs by using total reflection, discoloration can be reduced. The pitch of the convex portions may be the shortest distance from a starting point of one convex portion to a starting point of another adjacent convex portion. Specifically, the pitch of the convex portions may mean the shortest distance between a vertex of one convex portion and a vertex of another adjacent convex portion. The period may be about 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, or 40 μm or more in another example. Also, the period may be 50 μm or less in another example.

In one example, the number of convex portions of the first region, the second region, and/or the third region may be appropriately selected in consideration of the purpose of the present application. The convex portion may be present in an amount of 400/mm ² to 10,000/mm ² per unit area based on the surface direction of the optical film. In another example, the ratio may be 400/mm ² or more, 450/mm ² or more, or 500/mm ² or more. In addition, the ratio is 10000 / mm ² or less in another example, 9000 / mm 2 or less, 8000 / mm ² or less, 7000 / mm ^{2 or} less, 6000 / mm ² or less, 5000 / mm ² or less, 4000 pieces/mm ² or less, 3000 pieces/mm ² or less, 2000 pieces/mm ² or less, 1000 pieces/mm 2 or less, 900 pieces/mm ^{2 or} less, 800 pieces/mm ^{2 or} less, 700 pieces/mm ² or less, or 600 pieces/mm ² or less. In this case, the object of the present application can be achieved more effectively.

In one example, the first inclined surface and/or the second boundary surface may have a structure in which a plurality of linear prisms are arranged in one direction. In the present specification, a linear prism may refer to a shape in which a pillar having a triangular cross section extends in a straight direction. In one example, a direction in which the linear prisms are arranged on the first inclined surface and a direction in which the linear prisms are arranged on the second inclined surface may be perpendicular to each other. Accordingly, it may be advantageous to alleviate the discoloration phenomenon in both vertical and horizontal directions.

In one example, surfaces opposite to the first and second boundary surfaces of the first region and the second region may be flat. Since both surfaces of the third region are the first boundary surface and the second boundary surface, respectively, they may not have flat surfaces. In one example, a base layer may be present on at least one of the flat surfaces of the first region and the second region. A plastic film may be used as the base layer. As the plastic film, TAC (triacetyl cellulose); COP (cyclo olefin copolymer), such as a norbornene derivative; PMMA (poly(methyl methacrylate); PC (polycarbonate); PE (polyethylene); PP (polypropylene); PVA (polyvinyl alcohol); DAC (diacetyl cellulose); Pac (polyacrylate); PES (poly ether sulfone); PEEK (polyetheretherketon ); PPS (polyphenylsulfone), PEI (polyetherimide); PEN (polyethylenemaphthatlate); PET (polyethyleneterephtalate); PI (polyimide); PSF (polysulfone); PAR (polyarylate) or an amorphous fluorine resin.

The optical film of the present application applies a layer of material in one of the first and second areas on a flat substrate layer, transfers a boundary surface composed of a plurality of inclined surfaces to the layer, and then It may be manufactured by applying a layer, transferring a boundary surface composed of a plurality of inclined surfaces to the layer, and then applying a layer of another material of the first area and the second area. The transfer of the boundary surface composed of a plurality of inclined surfaces may be performed by roll-to-roll processing. A bite as shown in FIG. 5 may be used as a mold used for the roll-to-roll processing. In the case of arranging the convex portions in multiple dimensions, a plurality of rule-to-roll processes may be performed in different horizontal directions.

This application relates to a liquid crystal display including the optical film. The liquid crystal display may include a liquid crystal panel and an optical film of the present application disposed on a viewer-side surface of the liquid crystal panel.

As shown in FIG. 6 , the optical film 1 may be disposed on the viewing side surface 2A of the liquid crystal panel 2 . In this specification, the term viewer-side surface of a liquid crystal panel refers to a surface closer to an observer observing an image when the display displays an image among the upper and lower surfaces of the liquid crystal panel. Further, the term rear-side (2B) surface of the liquid crystal panel means a surface on the opposite side to the viewing-side surface among the upper and lower surfaces.

In this application, the arrangement of the optical film on the viewer-side surface of the liquid crystal panel means that the optical film is disposed in contact with the viewer-side surface as well as the presence of other components between the optical film and the viewer-side surface. case may be included. For example, as will be described later, a second polarizing plate may be disposed between the optical film and the viewing side surface of the liquid crystal panel.

The optical film may be disposed on the outermost side of the liquid crystal display. In the present application, that the optical film is disposed on the outermost surface of the liquid crystal display may mean that one surface of the optical film is exposed to the outside and is disposed so as to come into contact with air.

The first area of the optical film may be disposed closer to the liquid crystal panel than the second area. The optical film may be disposed such that light emitted from the liquid crystal panel sequentially passes through the first area, the third area, and the second area and is emitted. When light is incident from a medium with a high refractive index toward a medium with a low refractive index, when the incident angle is greater than a critical angle, it has a characteristic of total reflection. The present application can increase the reflectance of light that is 10 to 20 degrees of the internal angle of the light source and lower the reflectance of other lights by using the total reflection principle and the inclination angle. Since the reflected light can be emitted in different directions, the overall luminance can be uniformly adjusted.

In one example, the optical film may increase light at an internal angle of 10 degrees to 20 degrees of the liquid crystal panel to an angle at which discoloration occurs. In one example, among light incident from the liquid crystal panel to the optical film, light having an incident angle within a range of 10 degrees to 20 degrees may be emitted through the optical film at an emission angle of 30 degrees to 70 degrees.

In the present application, a method of disposing the optical film as described above on the viewing side surface of the liquid crystal panel is not particularly limited. For example, in the process of assembling a liquid crystal display, a method of simply placing the optical film on the viewer-side surface or attaching the optical film to the surface of the liquid crystal panel using an appropriate double-sided adhesive or adhesive may be applied. can

In one example, the liquid crystal panel may be a VA (Vertical Alignment) mode liquid crystal panel. In another example, the liquid crystal panel may be a twisted nematic (TN) mode liquid crystal panel. The optical film unique to the present application is disposed on the viewer-side surface of the liquid crystal panel to ensure uniformity of emitted light in front and viewing angles in various types of liquid crystal panels, and to eliminate color washout that may occur in a white state. And these effects can be appropriately expressed especially in a liquid crystal display of VA mode or TN mode.

A specific configuration of the liquid crystal panel applied in the present application is not particularly limited, and all known general configurations of the liquid crystal panel may be applied.

For example, the liquid crystal panel may be a transmissive liquid crystal panel, a reflective liquid crystal panel, or a transflective liquid crystal panel. In the present application, the driving method of the liquid crystal panel is not particularly limited, for example, a passive matrix method, an active matrix method using an active electrode such as a thin film transistor (TFT) electrode or a thin film diode (TFD) electrode, or a plasma address method. A known driving method such as the like may be applied.

A liquid crystal panel typically includes a liquid crystal layer including a liquid crystal material interposed between two transparent substrates. The transparent substrate of the liquid crystal panel may have a property of aligning the liquid crystal material constituting the liquid crystal layer in a specific alignment direction. For example, the substrate itself has a property of aligning liquid crystals, or a transparent substrate provided with an alignment film or the like having a property of aligning a liquid crystal material, although the substrate itself has no alignment ability, may be used. A known electrode such as ITO (Indium Tin Oxide) may be applied as an electrode of the liquid crystal panel. These electrodes can be usually installed on the surface of the transparent substrate in contact with the liquid crystal layer, or can be installed between the substrate and the alignment layer in the case of using a transparent substrate having an alignment layer.

As the liquid crystal material included in the liquid crystal layer, materials having various negative or positive dielectric constant anisotropy generally used in liquid crystal panels may be used. Examples of such materials include various low-molecular liquid crystal materials, high-molecular liquid crystal materials, and mixtures thereof, but are not limited thereto. In addition, the liquid crystal layer of the liquid crystal panel may include a pigment, a chiral agent, or a non-liquid crystal material within a range that does not impair the liquid crystal properties of the liquid crystal material.

In addition, a transflective liquid crystal panel may be constituted by replacing one substrate in the liquid crystal panel, for example, a substrate on the rear side with a substrate having a region having a reflective function and a region having a transmission function. A region having a reflective function (hereinafter referred to as a reflective layer) included in a transflective electrode used in such a liquid crystal panel is not particularly limited, but is a metal such as aluminum, silver, gold, chromium, platinum, or any one of these An alloy containing the above, an oxide such as magnesium oxide, a multilayer film of a dielectric, a liquid crystal exhibiting selective reflection, or a combination thereof may be exemplified. These reflective layers may be flat or curved. Further, the reflective layer may be formed by processing a surface shape such as a concave-convex shape to have diffuse reflectivity, a layer in which electrodes on the transparent substrate are combined on the rear side of a liquid crystal panel, or a combination thereof.

The liquid crystal panel may include other constituent members in addition to the above constituent members. For example, by attaching a color filter, a color liquid crystal display capable of providing multicolor or pure color display with high color purity can be manufactured.

The liquid crystal display may further include a backlight unit, a first polarizing plate, and a second polarizing plate. In the liquid crystal display, the backlight unit, the first polarizing plate, the liquid crystal panel, the second polarizing plate, and the optical film may be sequentially disposed. Absorption axes of the first and second polarizers may be orthogonal to each other.

The first polarizing plate or the second polarizing plate polarizes the incident light, and a polarizer commonly known to those skilled in the art, for example, a polyvinyl alcohol-based polarizer obtained by uniaxially stretching a polyvinyl alcohol-based film or a polyvinyl alcohol-based film. A dehydrated polyene-based polarizer may be included. Each of the first polarizer or the second polarizer may further include a protective film.

The first polarizing plate or the second polarizing plate may be attached to the liquid crystal panel by an adhesive layer or an adhesive layer. The adhesive layer or adhesive layer may be formed of a composition comprising an adhesive resin and, optionally, a crosslinking agent, a silane coupling agent, a photoradical initiator, or a photocationic initiator. The adhesive layer or the adhesive layer may increase the light diffusion effect by further including a light diffusing agent. The light diffusing agent may include conventional light diffusing agents known to those skilled in the art.

The backlight unit may include a light source. The backlight unit may further include a light guide plate for guiding light emitted from the light source, a reflective sheet positioned below the light guide plate, and a diffusion sheet positioned above the light guide plate. The light source generates light and may be disposed on a side surface of the light guide plate (edge type). As the light source, various light sources such as line light source lamps, surface light source lamps, CCFLs, or LEDs may be used. A light source cover may be disposed outside the light source. The light guide plate may guide light generated from the light source to the diffusion sheet. The light guide plate may be omitted when a direct light source is used, and in this case, a diffusion plate may be further included. The reflective sheet may serve to reflect the light generated from the light source and supply it in the direction of the diffusion sheet. The diffusion sheet may diffuse and scatter light incident through the light guide plate and supply the light to the liquid crystal panel.

The liquid crystal display may include other known members constituting the liquid crystal display in addition to the liquid crystal panel and the optical film. As such a member, for example, a polarizing plate, a backlight module, or a reflector may be exemplified, but is not limited thereto.

In the present application, a liquid crystal display capable of improving the luminance uniformity and contrast ratio of emitted light by selectively adjusting the reflection of light that causes discoloration in both vertical and horizontal directions by applying an optical film having a specific structure is provided. can do.

1 to 4 exemplarily show the optical film of the present application.
5 exemplarily shows a roll-to-roll mold.
6 exemplarily shows the liquid crystal display of the present application.

Although the present application is specifically described through the following examples, the scope of the present application is not limited by the following examples.

Optical property simulation evaluation method

For simulation evaluation of optical properties, a structure in which an optical film having the structure of FIG. 1 was disposed on the surface of the liquid crystal panel on the viewer side was set. The optical film has a structure in which a plurality of linear prisms are arranged in one direction, and the first area is disposed closer to the liquid crystal panel than the second area. A structure in which an optical film is not disposed is defined as Comparative Example 1. In the table below, n ₁ is the refractive index of the first region, n ₂ is the refractive index of the second region, n ₃ is the refractive index of the third region, and α is the first slope and the second slope respectively adjacent to each other. is the angle that That is, in this evaluation, the value of α ₁ and the value of α ₂ are the same.

Breault Research Organization's ASAP program was used for the simulation, and the light distribution obtained by measuring the liquid crystal panel using ELDIM's EZContrast equipment was used as a light source. The liquid crystal panel is T215HVN01.1 manufactured by AUO. Light source measurement was measured in gray units, and the unit is 0 (black), 64, 128, 192, 255 (white). For the simulation structure, the light from the liquid crystal panel was used as the light source, and the polarization was determined by the polarization direction of the polarizer attached to the outermost part of the liquid crystal panel. In addition, in the structure where the optical film adheres to the liquid crystal panel, the light distribution from the panel in each gray unit is measured by luminance, and the value is corrected so that 100% is obtained for each viewing angle when white (255) is obtained.

For the simulation structure, CR (contrast ratio) and horizontal and vertical Gary (difference ratio) were simulated, and the results are shown in Tables 1 to 2 below. The resulting values indicate CR (contrast ratio) and Gray (difference ratio) based on a liquid crystal panel without an optical film. The contrast ratio means the ratio (%) of the value obtained by dividing the white luminance of the simulation structure by the black luminance to the value obtained by dividing the white luminance of Comparative Example 1 by the black luminance. The difference ratio means the ratio (%) of the difference between viewing angles of the simulation structure to the difference between viewing angles of Comparative Example 1. The white luminance means the vertical luminance value in gray unit 255, and the black luminance means the vertical luminance value in gray unit 0. , 45 degrees, 60 degrees) means a value obtained by subtracting the largest value from the smallest value when the measured luminance value is expressed as normalized luminance. The lower the Gray value, the better the decolorization, and the higher the CR value, the better the optical properties. In this simulation evaluation, when the Gary value was 80 or less, it was evaluated that there was an effect of visually improving the decolorization phenomenon, and when the CR value was 80 or more, it was evaluated that the optical properties were visually excellent.

Table 1 below shows simulation evaluation results for Examples 1 to 4 satisfying all of Equations 1 to 4 of the present application.

Alpha (α)
n1 n2 n3 CR Horizontal Gray Vertical Gray Example 1 55 1.51 1.44 1.47 83 65 67 Example 2 45 1.565 1.505 1.535 82 71 70 Example 3 50 1.56 1.5 1.52 86 77 76 Example 4 50 1.565 1.5 1.53 86 69 79

10: 1st area, 20: 2nd area, 30: 3rd area 40: base layer,
DESCRIPTION OF SYMBOLS 1: Optical film 2: Liquid crystal panel 2A: Visual side 2B: Rear side
P: period, H: height, A: emission axis

Claims (17)

A first region and a second region having different refractive indices and a third region between the first region and the second region, and the first region and the third region are divided by a first boundary surface composed of a plurality of inclined surfaces, The second region and the third region are divided by a second interface composed of a plurality of inclined surfaces, the first region has a higher refractive index than the second region, and the third region has a lower refractive index than the first region. In the optical film having a higher refractive index than the second region,
The first combination of the refractive index of the first region (n ₁ ), the refractive index of the third region (n ₃ ) and the inclination angle of the first interface (α ₁ ), the refractive index of the third region (n ₃ ), and the second region The second combination of the refractive index (n ₂ ) and the inclination angle (α ₂ ) of the second interface is an optical film that satisfies Equation 1 below:
[Formula 1]

In Equation 1, n _A means n ₁ in the first combination and n ₃ in the second combination, n _B means n ₃ in the first combination and n 2 in the second combination, and α means n ₂ in the first combination. α ₁ means α ₂ in the second combination. A first region and a second region having different refractive indices and a third region between the first region and the second region, and the first region and the third region are divided by a first boundary surface composed of a plurality of inclined surfaces, The second region and the third region are divided by a second interface composed of a plurality of inclined surfaces, the first region has a higher refractive index than the second region, and the third region has a lower refractive index than the first region. In the optical film having a higher refractive index than the second region,
A first combination of the refractive index of the first region (n ₁ ) and the inclination angle of the first interface (α ₁ ), and a second combination of the refractive index of the third region (n ₃ ) and the inclination angle of the second interface (α ₂ ) is an optical film that satisfies Equation 2 below, respectively:
[Formula 2]

In Equation 2, n _A means n ₁ in the first combination and n ₃ in the second combination, and α means α ₁ in the first combination and α ₂ in the second combination. A first region and a second region having different refractive indices and a third region between the first region and the second region, and the first region and the third region are divided by a first boundary surface composed of a plurality of inclined surfaces, The second region and the third region are divided by a second interface composed of a plurality of inclined surfaces, the first region has a higher refractive index than the second region, and the third region has a lower refractive index than the first region. In the optical film having a higher refractive index than the second region,
The first combination of the refractive index of the first region (n ₁ ), the refractive index of the third region (n ₃ ) and the inclination angle of the first interface (α ₁ ), the refractive index of the third region (n ₃ ), and the second region The second combination of the refractive index (n ₂ ) and the inclination angle (α ₂ ) of the second interface is an optical film that satisfies Equation 3 below:
[Formula 3]

In Equation 3, n _A means n ₁ in the first combination and n ₃ in the second combination, n _B means n ₃ in the first combination and n 2 in the second combination, and α means n ₂ in the first combination. α ₁ means α ₂ in the second combination. A first region and a second region having different refractive indices and a third region between the first region and the second region, and the first region and the third region are divided by a first boundary surface composed of a plurality of inclined surfaces, The second region and the third region are divided by a second interface composed of a plurality of inclined surfaces, the first region has a higher refractive index than the second region, and the third region has a lower refractive index than the first region. In the optical film having a higher refractive index than the second region,
The first combination of the refractive index of the first region (n ₁ ), the refractive index of the third region (n ₃ ) and the inclination angle of the first interface (α ₁ ), the refractive index of the third region (n ₃ ), and the second region The second combination of the refractive index (n ₂ ) and the inclination angle (α ₂ ) of the second interface is an optical film that satisfies Equation 4 below:
[Formula 4]

In Equation 4, n _A means n ₁ in the first combination and n ₃ in the second combination, n _B means n ₃ in the first combination and n 2 in the second combination, and α means n ₂ in the first combination. α ₁ means α ₂ in the second combination. A first region and a second region having different refractive indices and a third region between the first region and the second region, and the first region and the third region are divided by a first boundary surface composed of a plurality of inclined surfaces, The second region and the third region are divided by a second interface composed of a plurality of inclined surfaces, the first region has a higher refractive index than the second region, and the third region has a lower refractive index than the first region. In the optical film having a higher refractive index than the second region,
The first combination of the refractive index of the first region (n ₁ ), the refractive index of the third region (n ₃ ) and the inclination angle of the first interface (α ₁ ), the refractive index of the third region (n ₃ ), and the second region The second combination of the refractive index (n ₂ ) and the inclination angle (α ₂ ) of the second boundary surface satisfies all of Equations 1 to 4, respectively:
[Formula 1]

[Formula 2]

[Formula 3]

[Formula 4]

In Equations 1 to 4, n _A means n ₁ in the first combination and n ₃ in the second combination, n _B means n ₃ in the first combination and n ₂ in the second combination, and α is the first α ₁ in the combination and α ₂ in the second combination. A first region and a second region having different refractive indices and a third region between the first region and the second region, and the first region and the third region are divided by a first boundary surface composed of a plurality of inclined surfaces, The second region and the third region are divided by a second interface composed of a plurality of inclined surfaces, the first region has a higher refractive index than the second region, and the third region has a lower refractive index than the first region. In the optical film having a higher refractive index than the second region,
The inclination angle (α ₁ ) of the first boundary surface and the inclination angle (α ₂ ) of the second boundary surface are each independently in the range of 35 degrees to 70 degrees, and the refractive index (n ₁ ) of the first region and the refractive index (n _{3 )} of the third region are ), and the second combination for the refractive index (n ₃ ) and the refractive index (n ₂ ) of the third region satisfy Equation 5 below:
[Formula 5]

In Equation 5, n _A means n ₁ in the first combination and n ₃ in the second combination, and n _B means n ₃ in the first combination and n ₂ in the second combination. A first region and a second region having different refractive indices and a third region between the first region and the second region, and the first region and the third region are divided by a first boundary surface composed of a plurality of inclined surfaces, The second region and the third region are divided by a second interface composed of a plurality of inclined surfaces, the first region has a higher refractive index than the second region, and the third region has a lower refractive index than the first region. In the optical film having a higher refractive index than the second region,
The inclination angle (α ₁ ) of the first boundary surface and the inclination angle (α ₂ ) of the second boundary surface are each independently in the range of 70 degrees to 110 degrees, and the refractive index (n ₁ ) of the first region and the refractive index (n _{3 )} of the third region are ) and the inclination angle of the first interface (α ₁ ), the refractive index of the third region (n ₃ ), the refractive index of the second region (n ₂ ) and the inclination angle of the second boundary (α ₂ ) The two combinations are optical films that each satisfy Equation 6 below:
[Formula 6]

In Equation 6, n _A means n ₁ in the first combination and n ₃ in the second combination, n _B means n ₃ in the first combination and n 2 in the second combination, and α means n ₂ in the first combination. α ₁ means α ₂ in the second combination. The optical film according to any one of claims 1 to 7, wherein each of the first boundary surface and the second boundary surface has a structure in which a plurality of linear prisms are arranged in one direction. The optical film of claim 8 , wherein an arrangement direction of the linear prisms on the first boundary surface and an arrangement direction of the linear prisms on the second boundary surface are perpendicular to each other. The optical film according to any one of claims 1 to 7, wherein surfaces opposite to the first and second boundary surfaces of the first region and the second region are flat. The optical film of claim 10 , wherein a substrate layer is present on at least one of flat surfaces of the first region and the second region. A liquid crystal display comprising a liquid crystal panel and the optical film according to any one of claims 1 to 7 disposed on a surface of the liquid crystal panel on a viewing side of the liquid crystal panel. The liquid crystal display of claim 12 , wherein the liquid crystal panel is a vertical alignment (VA) mode liquid crystal panel. The liquid crystal display according to claim 12, wherein the liquid crystal panel is a TN (Twisted Nematic) mode liquid crystal panel. 13. The liquid crystal display according to claim 12, wherein the first area of the optical film is disposed closer to the liquid crystal panel than the second area. The liquid crystal display of claim 12 , wherein among light incident from the liquid crystal panel to the optical film, light having an incident angle within a range of 10 degrees to 20 degrees is emitted through the optical film at an emission angle of 30 degrees to 70 degrees. delete

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