Optical film and backlight unit

Abstract

To provide an optical film and a backlight unit.SOLUTION: An optical film may include: a first sheet including a first base part, a pyramid pattern layer where a plurality of pyramid patterns with a length of a base being a first pitch and a length of a diagonal line being a first -1 pitch is formed on a first surface of the first base part, and a first prism pattern layer where a plurality of first prism patterns with a length of a base being a second pitch is formed on a second surface of the first base part; and a third sheet including a second base part, a second prism pattern layer where a plurality of second prism patterns is formed on a first surface of the second base part, and a first diffusion layer formed on a second surface of the second base part, and also including a second diffusion layer formed on a second surface of a third base part, in which the second diffusion layer faces a third prism pattern layer and is disposed overlappingly on the second sheet.SELECTED DRAWING: Figure 4a

Description

[Technical field]

[0001] Various embodiments of the present disclosure relate to optical films for use in liquid crystal display devices. [Background technology]

[0002] In general, a liquid crystal display (LCD) device may include a backlight unit that uniformly irradiates light onto the entire screen of an electronic device. The backlight unit may include a light source, a light guide plate, a diffusion sheet, and an optical film including a prism. Light emitted from the light source is transmitted to an upper portion through the light guide plate, and the light transmitted to the upper portion may be diffused through the diffusion sheet and then transmitted to the liquid crystal panel through the optical film provided on the upper portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Korean Patent Publication No. 10-2022-0060922 Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, display devices have been developed with a gradually thinner thickness, which requires that backlight units also be manufactured with a thinner thickness. In the backlight unit, development is being carried out to remove the diffusion sheet having a relatively thick thickness. For example, research is being carried out to remove or replace the diffusion sheet from an embodiment of the backlight unit including a light source, a light guide plate, a diffusion sheet, and a prism sheet.

[0005] The diffusion sheet may have a diffusion layer formed on one side and / or the other side. The diffusion layer generally contains light diffusing beads, and when light provided from the light source and the light guide plate is directed toward the prism sheet, it spreads the light over a wider range and acts as a shielding sheet that reduces the visibility of the light source.

[0006] However, the diffusion sheet is generally thick and hinders improvement of the brightness of the backlight unit, so efforts are being made to replace it.

[0007] Furthermore, when a sheet including a pyramid pattern and an inverse prism pattern is used instead of the diffusion sheet, a problem of moire occurring may occur depending on the arrangement of the pyramid pattern and the inverse prism pattern.

[0008] The present invention aims to provide, through various embodiments, an optical film for liquid crystal display devices that has excellent performance in preventing the shape of a light source from being visible (hereinafter also referred to as "shielding performance") without the use of a thick diffusion sheet, and at the same time has high brightness (hereinafter also referred to as "brightness performance").

[0009] Furthermore, an object of the present disclosure is to provide an optical film for effectively avoiding moire when a sheet including a pyramid pattern and an inverse prism pattern is used instead of a diffusion sheet. [Means for solving the problem]

[0010] According to various embodiments of the present disclosure, an optical film includes a first sheet including a first base portion, a pyramid pattern layer on a first surface of the first base portion, the pyramid pattern layer having a plurality of pyramid patterns with a base length of a first pitch and a diagonal length of a 1-1 pitch, and a first prism pattern layer on a second surface of the first base portion, the plurality of first prism patterns with a base length of a second pitch, a second base portion, a second prism pattern layer on a first surface of the second base portion, the plurality of second prism patterns on a second surface of the second base portion, and a second prism pattern layer on a third surface of the second base portion. the first prism pattern layer is disposed on a first surface of the third base portion, the second prism pattern layer has a plurality of third prism patterns formed thereon, and a second prism layer is disposed on a second surface of the third base portion, the second prism pattern layer is disposed on a second surface of the third base portion, the second prism pattern layer is disposed on a third sheet, and the plurality of first prism patterns have ridges extending in a first direction. an extension direction of any of the bases of the plurality of pyramid patterns forms an angle of 0 degrees or more and 45 degrees or less with the first direction, the plurality of second prism patterns form ridgelines in a second direction perpendicular to the first direction, and the plurality of third prism patterns form ridgelines in a third direction perpendicular to the second direction.

[0011] According to various embodiments of the present disclosure, a backlight unit includes an edge-type light source and the optical film disposed over the light source, the optical film including a first sheet including a first base portion, a pyramid pattern layer on a first surface of the first base portion, the pyramid pattern layer having a plurality of pyramid patterns with a base length of a first pitch and a diagonal length of a 1-1 pitch, and a first prism pattern layer on a second surface of the first base portion, the pyramid pattern layer having a plurality of first prism patterns with a base length of a second pitch, a second base portion, and a plurality of second prism patterns formed on the first surface of the second base portion. a third base portion, a third prism pattern layer having a plurality of third prism patterns formed on a first surface of the third base portion, and a first diffusion layer formed on a second surface of the second base portion, the first diffusion layer facing the pyramid pattern layer and a second sheet disposed over the first sheet, the third base portion, a third prism pattern layer having a plurality of third prism patterns formed on a first surface of the third base portion, and a second diffusion layer formed on the second surface of the third base portion, the second diffusion layer facing the third prism pattern layer and including a third sheet disposed over the second sheet, the plurality of first prism patterns having ridges extending in a first direction a backlight unit can be provided in which an extension direction of any of the bases of the plurality of pyramid patterns forms an angle of 0 degrees or more and 45 degrees or less with the first direction, the plurality of second prism patterns form ridgelines in a second direction that is perpendicular to the first direction, and the plurality of third prism patterns form ridgelines in a third direction that is perpendicular to the second direction.

[0012] According to various embodiments of the present disclosure, an optical film can be provided that includes a first base portion, a pyramid pattern layer having a plurality of pyramid patterns formed on a first surface of the first base portion, the pyramid patterns having a base length of a first pitch and a diagonal length of a 1-1 pitch, and a first prism pattern layer having a plurality of prism patterns formed on a second surface of the first base portion, the plurality of first pyramid patterns forming a ridge line toward a first direction, and the extension direction of any of the bases of the plurality of pyramid patterns forming an angle of 0 degrees or more and 45 degrees or less with the first direction. Effect of the Invention

[0013] According to various embodiments of the present disclosure, a thick diffusion sheet is not provided, which can contribute to making the backlight unit thinner.

[0014] According to various embodiments of the present disclosure, it is possible to provide an optical film having excellent light source shielding performance and excellent brightness performance, and a backlight unit including the same.

[0015] According to various embodiments of the present disclosure, it is possible to provide an optical film and a backlight unit including the same in which moire is reduced and / or prevented.

[0016] The effects obtained by the present disclosure are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by a person having ordinary skill in the art to which the present disclosure pertains from the following description.

[0017] The above-mentioned aspects and other aspects, features and / or advantages of an embodiment of the present disclosure may become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0018] [Figure 1]1 is a perspective view illustrating a liquid crystal display device including an optical film according to an embodiment. [Diagram 2] 1 is a diagram illustrating a liquid crystal display device including an optical film according to an embodiment. [Diagram 3] 1 is a diagram illustrating a liquid crystal display device including an optical film according to an embodiment. [Figure 4a] FIG. 1 is a cross-sectional view showing an optical film according to an embodiment. [Figure 4b] FIG. 1 is a cross-sectional view showing an optical film according to an embodiment. [Figure 4c] FIG. 1 is a cross-sectional view showing an optical film according to an embodiment. [Figure 4d] FIG. 2 illustrates a pyramid pattern and a prism pattern according to one embodiment. [Figure 4e] 1 illustrates a top view of a pyramidal pattern layer prior to lamination according to one embodiment. [Figure 4f] FIG. 2 illustrates a top view of a pyramidal pattern layer after lamination according to one embodiment. [Figure 5a] 1 shows an experimental setup for measuring the brightness of an optical film according to one embodiment. [Figure 5b] FIG. 2 illustrates a light distribution diagram and optimal incidence angle for enhanced brightness according to one embodiment. [Figure 6a] FIG. 13 is a diagram showing a backlight unit including a sheet on which an inverse prism pattern layer (first prism pattern layer) is formed and an edge-type light source according to a certain embodiment. [Figure 6b] FIG. 13 is a diagram showing the change in the incident angle and the viewing angle due to the change in the refractive index of the inverse prism pattern layer. [Figure 7] 1 is a perspective view illustrating a liquid crystal display device including an optical film according to an embodiment. [Figure 8a] FIG. 1 illustrates optical characteristics of a liquid crystal display device including a diffuser plate according to some embodiments. [Figure 8b] 1 is a diagram illustrating optical characteristics of a liquid crystal display device including an optical film according to an embodiment. [Figure 8c] 1 is a diagram illustrating optical characteristics of a liquid crystal display device including an optical film according to an embodiment. [Figure 9a] 1 is a diagram illustrating optical characteristics of a liquid crystal display device including an optical film according to an embodiment. [Figure 9b] 1 is a diagram illustrating optical characteristics of a liquid crystal display device including an optical film according to an embodiment. [Figure 9c] 1 is a diagram illustrating optical characteristics of a liquid crystal display device including an optical film according to an embodiment. [Figure 9d] FIG. 2 is a diagram showing optical characteristics of a liquid crystal display device including an optical film according to an embodiment. [Figure 10a] FIG. 2 is a diagram showing the appearance of a liquid crystal panel according to an arrangement of a first prism pattern layer and a pyramid pattern layer according to an embodiment. [Figure 10b] FIG. 2 is a diagram showing the appearance of a liquid crystal panel according to an arrangement of a first prism pattern layer and a pyramid pattern layer according to an embodiment.

[0019] Similar reference numbers may be used to refer to similar components, structures and / or structures throughout the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The various embodiments of the present disclosure and the terms used therein are not intended to limit the technical features described in the present disclosure to a specific embodiment, but should be understood to include various modifications, equivalents, or alternatives of the embodiment. In connection with the description of the drawings, similar reference numerals may be used for similar or related components. The singular form of a noun corresponding to an item may include one or more of the said items, unless otherwise specified in the relevant context.

[0021] According to various embodiments, each of the aforementioned components (e.g., modules or programs) may include one or more objects, and some of the objects may be located separately in other components. According to various embodiments, one or more of the aforementioned components or operations may be omitted, or one or more other components or operations may be added. Alternatively or additionally, multiple components (e.g., modules or programs) may be integrated into one component. In such a case, the integrated component may perform one or more functions of each of the multiple components in the same or similar manner as those performed by the multiple components before integration. According to various embodiments, operations performed by a module, program, or other component may be performed sequentially, in parallel, iteratively, or heuristically, or one or more of the operations may be performed in a different order, omitted, or one or more other operations may be added.

[0022] Various embodiments will be described below with reference to the accompanying drawings. In describing the present embodiments, the same names and the same reference numerals will be used for the same configurations, and additional description thereof will be omitted. In describing the embodiments of the present invention, it should be noted that the same names and the same reference numerals will be used for components having the same functions, but they are not substantially the same as those of the prior art.

[0023] In various embodiments, terms such as "comprise" or "have" are intended to indicate the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, but should be understood not to preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0024] FIG. 1 is a perspective view showing a liquid crystal display device including an optical film according to an embodiment.

[0025] In the following detailed description, the longitudinal direction (vertical direction) of the liquid crystal display device 1 can be defined as the "Y-axis direction", the width direction (horizontal direction) as the "X-axis direction", and / or the height direction (thickness direction) as the "Z-axis direction". Furthermore, in some embodiments, for the direction in which the components are oriented, "negative / positive (- / +)" can be used in conjunction with the Cartesian coordinate system illustrated in the drawings. As shown in FIG. 1, when "negative / positive (- / +)" is not described in the Cartesian coordinate system, the relevant coordinate axis may be interpreted as pointing in the + direction unless otherwise defined. For example, the "X-axis direction" can be interpreted as pointing to the +X-axis direction, and the "Y-axis direction" can be interpreted as pointing to the +Y-axis direction. And the "Z-axis direction" can be interpreted as pointing to the +Z-axis direction. For example, referring to FIG. 1, if the second sheet 120 is arranged over the first sheet 110, the second sheet 120 can be defined as being arranged on the "+Z-axis direction (or first direction)" from the first sheet 110. Also, for example, referring to FIG. 4a, one surface (e.g., the first surface 112a) of the first base portion 112 can be defined as a "surface facing the +Z axis direction (or first direction)" and the other surface (e.g., the second surface 112b) can be defined as a "surface facing the -Z axis direction (or second direction)". According to one embodiment, the traveling direction of the light source in the description of the optical film 100 can be expressed as, for example, a "+Z axis direction". When describing the directions, in the following description of the directions, facing any one of the three axes of the Cartesian coordinate system may include facing a direction parallel to the axis. It should be noted that this is based on the Cartesian coordinate system described in the drawings for the sake of simplicity of description, and the description of such directions or components does not limit various embodiments of the present disclosure.

[0026] Referring to FIG. 1, a liquid crystal display device (or LCD (liquid crystal display) device) 1 may include a backlight unit 10 and a liquid crystal panel 20. According to various embodiments, the backlight unit 10 may face a rear surface (surface facing the -Z axis direction) of the liquid crystal panel 20 so as to emit light to the liquid crystal panel 20. The backlight unit 10 may include a light source 11, a light guide plate 12, a reflector 13, an optical film 100, and a diffusion sheet 17. The backlight unit 10 may further include a reflective polarizing sheet, although not shown in the drawings.

[0027] The light source 11 is configured to radiate light to the rear surface of the liquid crystal panel 20, and may be disposed on one side of a light guide plate (LPG) 12. The light source may be classified into an edge type or a direct type depending on the arrangement structure, and in the present disclosure, an edge type light source may be applied as shown in FIG. 1. The light source 11 is configured to irradiate light to the rear surface of the liquid crystal panel 20, and the light emitted from the light source 11 may be converted into a surface light source by the light guide plate 12. In this case, the light source 11 may be a cold cathode fluorescent lamp (CCFL) or an external electrode fluorescent lamp. The reflector 13 is disposed behind the light guide plate 12, and reflects and causes the light emitted toward the rear of the light guide plate 12 (the surface facing the -Z axis direction) to be incident toward the light guide plate 12, thereby minimizing the loss of light. That is, the reflector 13 may perform light recycling.

[0028] 1, the light emitted from the light guide plate 12 is incident on the optical film 100, and the optical film 100 of the present disclosure includes at least one prism sheet for concentrating the light, and may further include a sheet including a pyramid pattern as a sheet for uniformly dispersing the light incident from the light guide plate 12 and then causing it to be incident on the prism sheet. For convenience of explanation, hereinafter, one prism sheet for concentrating light included in the optical film 100 or a combination of two or more prism sheets is referred to as a "concentrating prism sheet" (or a "cross prism sheet"), and a sheet including a pyramid pattern is sometimes referred to as a "pyramid sheet".

[0029] As will be described in detail below, the optical film 100 of the present disclosure may include a first sheet 110 that is a pyramid sheet and has a pyramid pattern formed on one surface facing a direction parallel to the light source traveling direction (e.g., Z-axis direction) and a prism pattern (i.e., an inverted prism pattern) formed on the other surface facing the opposite direction to the light source traveling direction. The optical film 100 of the present disclosure may also include a second sheet as a light-collecting prism sheet, having a prism pattern formed on one surface facing a direction parallel to the light source traveling direction (e.g., +Z-axis direction) and a diffusion layer formed on the other surface facing the opposite direction to the light source traveling direction. According to an embodiment, the optical film 100 of the present disclosure may further include a third sheet 130 as a light-collecting prism sheet, in addition to the second sheet 120, and including a prism pattern whose ridgeline direction is different from that of the prism pattern formed on the second sheet 120.

[0030] The light-collecting prism sheet (the second sheet 120 and / or the third sheet 130) can collect incident light using an optical pattern formed on the surface and then emit the light to the liquid crystal panel 20. The light-collecting prism sheet (the second sheet 120 and / or the third sheet 130) can include a light-transmitting base film and a prism pattern layer formed on the upper surface (the surface facing the +Z axis direction) of the base film. The prism pattern layer can be formed of an optical pattern layer in the form of a triangular array in which an inclined surface of a specified angle (e.g., an inclined surface of 45°) is formed in order to improve the brightness in the surface direction. The prism pattern of the prism pattern layer may be in the form of a triangular prism, and one surface of the triangular prism may be disposed so as to face the base film. Each cross section of the prism pattern may be a triangle.

[0031] According to an embodiment, the condensing prism sheet (the second sheet 120 and / or the third sheet 130) may form a composite prism sheet structure including the second sheet 120 and the third sheet 130. Here, the third sheet 130 may be arranged to overlap the second sheet 120. In the second sheet 120, a plurality of second prism patterns may be arranged side by side. Each of the second prism patterns may be a structure extending in one direction. For example, each apex line (hereinafter referred to as a "crest or ridge") of the second prism pattern may be formed to extend in the X-axis direction. Similarly, in the third sheet 130, a plurality of third prism patterns may be arranged side by side. Each of the third prism patterns may be a structure extending in one direction. For example, each ridge line of the third prism pattern may be formed to extend in the Y-axis direction perpendicular to the X-axis. Here, for convenience of explanation, the extension direction of the first prism pattern and the extension direction of the second prism pattern are shown toward the X-axis and Y-axis, respectively. However, it should be noted that the present invention is not limited to the illustrated embodiment and may be oriented in a direction other than the X-axis or Y-axis.

[0032] According to an embodiment, a prism pattern (a plurality of first prism patterns) can also be formed on the pyramid sheet (first sheet 110). The plurality of first prism patterns included in the first sheet 110 may be formed to protrude in the opposite direction (-Z axis direction) to the traveling direction of light, unlike the plurality of second prism patterns included in the second sheet 120 and the plurality of third prism patterns included in the third sheet 130, instead of the direction parallel to the traveling direction of light (+Z axis direction). Therefore, the plurality of first prism patterns included in the first sheet 110 may be called "inverse prism patterns". The ridge direction P1 of the plurality of first prism patterns can be formed to be the same as or different from the ridge direction P2 of the plurality of second prism patterns and the ridge direction P3 of the plurality of third prism patterns. 1, the ridge direction P1 of the first prism patterns can be formed perpendicular to the ridge direction P2 of the second prism patterns and parallel to the ridge direction P3 of the third prism patterns, and the liquid crystal display device 1 of the present disclosure can achieve the corresponding effects. The ridge directions will be described in more detail later.

[0033] The diffusion sheet 17 can uniformly disperse the light incident from the optical film 100. The diffusion sheet 17 can cause light diffusion by applying a solution of a curable resin (e.g., at least one selected from urethane acrylate, epoxy acrylate, ester acrylate, and radical-generating monomer, or a mixture of two or more) to which light diffusing agent beads are added. In addition, the diffusion sheet 17 can form a protrusion pattern (or protrusions) of a uniform or non-uniform size and shape (e.g., spherical, hemispherical, or elliptical) to promote light diffusion. According to some embodiments of the prior art, the diffusion sheet 17 may include not only the upper diffusion sheet 17 arranged over the light-collecting prism sheet shown in FIG. 1, but also a lower diffusion sheet arranged below the light-collecting prism sheet. However, in the present disclosure, the lower diffusion sheet can be replaced by providing an optical film 100 in which a light-collecting prism sheet and a pyramid sheet are combined.

[0034] According to one embodiment, the backlight unit 10 may omit at least one of the aforementioned components (e.g., the diffusion sheet 17) or may add one or more other components (e.g., a reflective polarizing sheet (not shown)).

[0035] A reflective polarizing sheet (not shown) is provided on the top of the optical film 100 and the diffusion sheet 17, and serves to transmit some of the polarized light collected from the optical film 100 and diffused by the upper diffusion sheet, and to reflect the other polarized light downward.

[0036] The liquid crystal panel 20 can refract the light emitted from the light source 11 into a predetermined pattern in response to an electrical signal. This refracted light passes through a color filter and a polarizing filter arranged in front of the liquid crystal panel 20 to form a screen.

[0037] Components included in the liquid crystal display device 1 of Fig. 1 can be assembled in a state where they are overlapped and stacked with other components in the height direction (+Z-axis direction). For example, in the liquid crystal display device 1 according to some embodiments, as shown in Fig. 1, a backlight unit 10 and a liquid crystal panel 20 that are manufactured separately can be overlapped and stacked in the height direction (+Z-axis direction).

[0038] 2 and 3 are diagrams illustrating a liquid crystal display device including an optical film according to an embodiment.

[0039] Fig. 2 can show a cross section parallel to the plane formed by the Y-axis and Z-axis of the liquid crystal display device 1, and Fig. 3 can show a cross section parallel to the plane formed by the X-axis and Z-axis of the liquid crystal display device 1. Hereinafter, explanations of parts that overlap with Fig. 1 will be omitted.

[0040] The liquid crystal display device 1 of the present disclosure can be characterized in that no separate diffusion sheet (e.g., a lower diffusion sheet) is provided between the optical film 100 and the light guide plate 12, and the diffusion sheet is replaced only by the optical film 100 of the present disclosure.

[0041] In the present disclosure, the "optical film 100" may be a film including a first sheet 110 having a plurality of pyramid patterns formed on one surface, a second sheet 120 disposed on the first sheet 110 having a plurality of prism patterns formed on one surface, and a third sheet 130 disposed on the second sheet 120 having a plurality of prism patterns formed on one surface, as shown in Figs. 1 to 3. For convenience of explanation, in Figs. 1 to 3, the first sheet 110, the second sheet 120, and the third sheet 130 are shown to be separated from each other, but, unlike this, the first sheet 110, the second sheet 120, and the third sheet 130 may be formed by lamination with each other. In the present disclosure, "lamination" may mean that two different sheets are bonded together by including a pattern formed of an adhesive resin on at least one of the opposing surfaces of the two different sheets. For example, one of the two opposing surfaces of two different sheets may have a pattern formed of a semi-cured adhesive resin, and the other surface may be in contact with this pattern, and then completely cured and bonded together. Also, for example, the opposing surfaces of the two different sheets may be formed of a semi-cured adhesive resin on both sides, and after contacting each other, they may be completely cured and bonded together. The optical film 100 in a laminated form can provide a backlight unit that is thinner and has excellent shielding performance than an embodiment in which the sheets are not laminated and are simply stacked.

[0042] The multiple pyramid (or quadrangular pyramid) patterns of the first sheet 110 can refract and / or reflect the light transmitted from the light source 11 and transmit the light to the second sheet 120. The second sheet 120 may be formed in a form in which multiple prisms (or triangular prisms) extend in the width direction (X-axis direction) of the liquid crystal display device 1 and protrude in the height direction (Z-axis direction). The second sheet 120 can transmit the light that has passed through the first sheet 110 to the third sheet 130. The third sheet 130 may be formed in a form in which multiple prisms (or triangular prisms) extend in the length direction (Y-axis direction) of the liquid crystal display device 1 and protrude in the height direction (Z-axis direction). The third sheet 130 can transmit the light that has passed through the second sheet 120 toward the liquid crystal panel 20. The light incident on the optical film 100 from the light source 11 is diffused and / or condensed while passing through the first sheet 110, the second sheet 120, and the third sheet 130 in sequence, which has the advantage of ensuring not only the shielding performance of covering the shape of the light source 11, but also high brightness performance. In the embodiment shown in Figs. 1 to 3, the multiple prism patterns of the second sheet 120 extend in the width direction (X-axis direction) of the liquid crystal display device 1, and the multiple prism patterns of the third sheet 130 extend in the longitudinal direction (Y-axis direction) of the liquid crystal display device 1, but this is not necessarily limited thereto, and differently, the multiple prism patterns of the second sheet 120 may extend in the longitudinal direction (Y-axis direction) of the liquid crystal display device 1, and the multiple prism patterns of the third sheet 130 may extend in the width direction (X-axis direction) of the liquid crystal display device 1. However, it is only necessary that the multiple prism patterns of the second sheet 120 and the multiple prism patterns of the third sheet 130 are perpendicular to each other. 1, the pyramid pattern layer 111 of the first sheet 110 may include a pyramid pattern (hereinafter, pyramid pattern 111a in FIG. 4a) including a base with a length a in a first direction and a length b in a second direction, four side surfaces 111-1, 111-2, 111-3, 111-4 having a height h, apex angles A and B, and one bottom surface. The dimensions of the pyramid pattern may be set differently depending on the embodiment.

[0043] The optical film 100 will now be described in more detail with reference to Figures 4a to 4f.

[0044] FIG. 4a is a cross-sectional view of an optical film according to an embodiment; FIG. 4b is a cross-sectional view of an optical film according to an embodiment; FIG. 4c is a cross-sectional view of an optical film according to an embodiment; FIG. 4d is a pyramid pattern and a prism pattern according to an embodiment; FIG. 4e is a top view of a pyramid pattern layer before lamination according to an embodiment; and FIG. 4f is a top view of a pyramid pattern layer after lamination according to an embodiment.

[0045] 4a to 4c, the optical film 100 according to an embodiment of the present disclosure may include an optical film 100a including a first sheet 110, an optical film 100b including the first sheet 110 and the second sheet 120, and an optical film 100c including the first sheet 110, the second sheet 120, and the third sheet 130. For example, the first sheet 110 may be used alone as a component of the optical film 100a without other sheets (e.g., the second sheet 120 and the third sheet 130). According to the present disclosure, the second sheet 120 and / or the third sheet 130 may further include the first sheet 110 to provide an optical film having excellent shielding performance against a light source and excellent brightness performance. Hereinafter, unless otherwise specified, for convenience, each component included in the optical film 100 may be described in detail using the optical film 100c of FIG. 4c as an example. According to one embodiment, it should be noted that not only an optical film of three sheets 110, 120, 130 (e.g., optical film 100c in FIG. 4c), but also an optical film of one sheet 110 (e.g., optical film 100a in FIG. 4a) and an optical film of two sheets 110, 120 (e.g., optical film 100b in FIG. 4b) may be included within the scope of the present invention.

[0046] 4c, in the optical film 100 (for example, optical film 100c), the first sheet 110, the second sheet 120, and the third sheet 130 may include a first base portion 112, a second base portion 122, and a third base portion 132, respectively. In this case, the first base portion 112, the second base portion 122, and the third base portion 132 may include a transparent material capable of transmitting light, for example, a polycarbonate-based, polysulfone-based, polyacrylate-based, polystyrene-based, polyvinyl chloride-based, polyvinyl alcohol-based, polynorbornene-based, or polyester-based material. As a specific example, the first base portion 112, the second base portion 122, and / or the third base portion 132 may be made of polyethylene terephthalate (PET) or polyethylene naphthalate. The first base portion 112, the second base portion 122, and the third base portion 132 may be made of PET having a thickness of, for example, about 10 to about 50 μm, and more specifically, may be made of PET having a thickness of about 24 to about 40 μm. In various experimental examples including the viewing angle distribution described later in the drawings from FIG. 6a onwards, the first base portion 112, the second base portion 122, and the third base portion 132 may be made of PET having a thickness of 24 μm. However, it should be noted that the thicknesses of the first base portion 112, the second base portion 122, and the third base portion 132 are not limited to the above examples.

[0047] 1, the first sheet 110 may include a pyramid pattern 111a in the form of a quadrangular pyramid on a first surface 112a of a first base portion 112, the pyramid pattern 111a corresponding to four side surfaces 111-1, 111-2, 111-3, and 111-4 that form a length a in a first direction, a length b in a second direction, a height h, a pitch P, and apex angles A and B. The optical film 100 may include a plurality of pyramid patterns 111a having a plurality of columns in a first direction and a plurality of rows in a second direction perpendicular to the first direction.

[0048] 4a and 4d, the pyramid pattern 111a according to an embodiment may be an intaglio pattern. The pyramid pattern 111a may mean an intaglio pattern in which quadrangular pyramid-shaped grooves are regularly formed, and may be defined by four side surfaces 111-1, 111-2, 111-3, and 111-4. Here, the four side surfaces may be the same or different triangular shapes, and the dimensions of the apex angle A and the apex angle B may be set according to the horizontal length a, the vertical length b, and the height of each cross section of the pyramid pattern 111a. According to an embodiment, the apex angle A and the apex angle B may form substantially the same angle, and therefore the horizontal length a and the vertical length b of the pyramid pattern 111a may also be set substantially equal. Here, the apex angle A and the apex angle B being substantially the same may mean that the apex angle A and the apex angle B have the same value within a process deviation (for example, within 10%).

[0049] Furthermore, the height h and pitch P of the pyramid pattern 111a can be set based on the apex angle C. The optical film 100 includes the pyramid pattern 111a whose vertical cross section parallel to the height direction (Z-axis direction) is triangular or trapezoidal, and the apex angle C can be defined as the angle between two opposing side surfaces among the four side surfaces of the pyramid pattern 111a.

[0050] According to an embodiment, the apex angle C of the pyramid pattern 111a may be defined as 60 degrees or more and 160 degrees or less. For example, the apex angle C may be 90 degrees. Within the specified range, the larger the apex angle C of the pyramid pattern 111a, the larger the angle θ (theta) of light incident on the second sheet 120 (hereinafter, referred to as the "incident angle θ"). For example, in an optical film including three sheets of the present disclosure (e.g., optical film 100c), the first sheet 110 including the pyramid pattern 111a can play a role in allowing light incident on the second sheet 120 and the third sheet 130 to be incident at an optimal angle that improves brightness. The relationship between the components of the optical film and brightness will be described in more detail below through the embodiments from FIG. 5 onwards.

[0051] According to one embodiment, the pyramid pattern 111a may also be formed as a relief pattern.

[0052] 4e shows the pyramid pattern layer before the first sheet 110 is laminated to the second sheet 120, and FIG. 4f shows the pyramid pattern layer after the first sheet 110 is laminated to the second sheet 120 and the first sheet 110 is peeled off from the second sheet 120. Referring to FIG. 4e, the pyramid pattern layer 111 before lamination may include a first partition wall 111-5 between the first side surface 111-1 and the fourth side surface 111-4 that distinguishes the boundary between the first side surface 111-1 and the fourth side surface 111-4, and may include a second partition wall 111-6 between the second side surface 111-2 and the third side surface 111-3 that distinguishes the boundary between the second side surface 111-2 and the third side surface 111-3. The first partition wall 111-5 and the second partition wall 111-6 may be the highest part of the first sheet 110. According to one embodiment, the first partition wall 111-5 is parallel to the first direction, and the second partition wall 111-6 is parallel to the second direction, but it should be noted that this is not necessarily limited to this. Referring to FIG. 4f, when the pyramid pattern layer 111 located on the upper surface of the first sheet 110 is laminated to the rear surface of the second sheet 120 (e.g., the first diffusion layer 123 on the rear surface of the second sheet 120), the ends of the first partition wall 111-5 and the second partition wall 111-6, which are the configurations located at the top end of the pyramid pattern layer 111, may be pressed. As a result, the tip of the first partition 111-5 is deformed to form a first flat portion 111-7 having a predetermined width W1, and the tip of the second partition 111-6 is deformed to form a second flat portion 111-8 having a predetermined width W2. According to one embodiment, the width W1 of the first flat portion 111-7 and the width W2 of the second flat portion 111-8 may be substantially equal.

[0053] According to various embodiments of the present disclosure, the pyramid pattern layer 111 can control light in four peripheral directions. According to one embodiment of the present disclosure, the pyramid pattern layer 111 can include pyramid patterns 111a having a vertex angle, which is an angle between two opposing triangles, of 90 degrees or more and 130 degrees or less. According to one embodiment, when the vertex angle of the pyramid pattern 111a is at least 90 degrees, it can satisfy the shielding performance as shown in FIG. 6a, and when the vertex angle is less than that, the hot spot visibility (HSV) at which the light source 11a is visible can be increased.

[0054] The pyramid pattern layer 111 may be composed of a plurality of pyramid patterns, and may be regularly arranged on the first surface 112a of the first sheet 110. A first prism pattern layer 113 including a plurality of first prism patterns may be formed on the second surface 112b of the first base portion 112. The first prism pattern layer 113 may have substantially the same configuration as the second prism pattern layer 121 provided on the second sheet 120 and the third prism pattern layer 131 provided on the third sheet 130, except for the direction in which they are arranged.

[0055] The second sheet 120 may include a second prism pattern layer 121 on a first surface 122a of a second base portion 122, in which a plurality of second prism patterns extending in parallel toward the width direction (or longitudinal direction) of the liquid crystal display device 1 are formed. The cross section of the second prism pattern layer 121 may be triangular. For example, the plurality of second prism patterns included in the second prism pattern layer 121 may be formed with a pitch of c and a height of d. The third sheet 130 may include a third prism pattern layer 131 on a first surface 132a of a third base portion 132, in which a plurality of third prism patterns extending in parallel toward the longitudinal direction (or width direction) of the liquid crystal display device 1 are formed. The cross section of the prism pattern formed in the third prism pattern layer 131 may be triangular. For example, the plurality of third prism patterns formed in the third prism pattern layer 131 may be formed with a pitch of e and a height of f. Here, the plurality of second prism patterns included in the second prism pattern layer 121 and the plurality of third prism patterns included in the third prism pattern layer 131 may be formed to extend in directions perpendicular to each other and have the same pitch and height, respectively, but this is not necessarily limited to this and may vary depending on the embodiment.

[0056] The second surface 122b of the second base portion 122 of the second sheet 120 may include a first diffusion layer 123, and the second surface 132b of the third base portion 132 of the third sheet 130 may include a second diffusion layer 133. The first diffusion layer 123 and the second diffusion layer 133 may be fabricated using any treatment method to increase turbidity, including a matte treatment in which the first diffusion layer 123 and the second diffusion layer 133 are roughened to increase turbidity, and a bead treatment in which beads such as glass or polymer are used to increase turbidity. For example, in various experimental examples including the viewing angle distribution described later in the drawings from FIG. 8a onwards, the first diffusion layer 123 may have a haze value of 3%, and the second diffusion layer 133 may have a haze value of 40%.

[0057] The first sheet 110 and the second sheet 120 may be connected in a form in which the pyramid pattern layer 111 of the first sheet 110 and the first diffusion layer 123 of the second sheet 120 are laminated to each other, and the second sheet 120 and the third sheet 130 may be connected in a form in which the second prism pattern layer 121 of the second sheet 120 and the second diffusion layer 133 of the third sheet 130 are laminated to each other. In this case, the first diffusion layer 123 and the second diffusion layer 133 may each be formed, for example, with a matte pattern using an adhesive (e.g., an adhesive resin), and may be initially laminated to another sheet in a state of about 50% curing (e.g., semi-curing) rather than 100% curing, and then laminated to another sheet by being 100% cured.

[0058] FIG. 5a shows an experimental setup for measuring the brightness of an optical film according to one embodiment. FIG. 5b shows the optimal incidence angle for enhancing light distribution and brightness according to one embodiment. In FIG. 5b, the viewing angle distribution can represent the distribution of light focused on a horizontal plane (e.g., a plane parallel to the XY plane).

[0059] Referring to FIG. 5a, an experimental setup for measuring luminance may include an optical film 100 and a light measuring device 210. Here, the optical film 100 may show a state in which a second sheet 120 and a third sheet 130 are bonded together, and the first sheet 110 may be omitted. The light measuring device 210 may be, for example, a high-speed spectroscopic measuring system such as a color luminance meter. Although not shown in the drawing, a backlight unit including a light source may be disposed on the opposite side of the light measuring device 210 with respect to the optical film 100.

[0060] As shown in FIG. 5a, the light measuring device 210 can measure light incident in the height direction (Z-axis direction) of the optical film 100. The light distribution can be shown as in FIG. 5b using a viewing angle distribution (BSDF, bidirectional scattering distribution function). In this case, in order to obtain high brightness for the liquid crystal display device 1, in the viewing angle data measured by the light measuring device 210, the brightness must be high near "light measuring device reference 0 degrees" parallel to the Z axis, which is the direction in which the light measuring device 210 faces, and it has been found from the experimental results that the brightness near 0 degrees is the largest when the light passing through the second sheet 120 and the third sheet 130 in the optical film 100 is incident at a specific angle. That is, the brightness of the liquid crystal display device 1 may be the largest when the light passing through the lower surface (for example, the second surface 122b of the second sheet 120) of the bonded body of the second sheet 120 and the third sheet 130 is incident at a specific incident angle θ. Here, the incident angle θ may refer to the angle made by the central light of the light (or light beam) exiting the first sheet 110 with respect to a normal line to the second surface 122b of the second sheet 120 as a reference.

[0061] For example, referring to one embodiment (Example 1-1) of Figure 5b, in an embodiment in which the second base portion 122 and the third base portion 132 each have a thickness of 24 μm, the pitch c of the prism pattern of the second prism pattern layer 121 formed on the first surface 122a of the second base portion 122 is 50 μm and the height d is 25 μm, the first diffusion layer 123 formed on the second surface 122b of the second base portion 122 has a haze value of 3%, the pitch e of the prism pattern of the third prism pattern layer 131 formed on the first surface 132a of the third base portion 132 is 50 μm and the height f is 25 μm, and the second diffusion layer 133 on the second surface 132b of the third base portion 132 has a haze value of 40%, the optimal incident angle θ at which the brightness is highest near 0 degrees based on the light measurement device can be formed at 65 degrees. That is, light passing through the underside of the laminate of the second sheet 120 and the third sheet 130 (e.g., the other surface 122b of the second sheet 120) may have the highest brightness value when incident at an angle of +65 degrees (or -65 degrees).

[0062] Further, for example, referring to one embodiment (Example 1-2) of FIG. 5b, in an embodiment in which the second base portion 122 and the third base portion 132 each have a thickness of 24 μm, the pitch c of the prism pattern of the second prism pattern layer 121 formed on the first surface 122a of the second base portion 122 is 45 and 55 μm, and the height d is 22.5 and 22.7 μm, and the pitch c of the prism pattern of the second prism pattern layer 121 formed on the second surface 122b of the second base portion 122 is 45 and 55 μm, and the height d is 22.5 and 22.7 μm. When the first diffusion layer 123 has a haze value of 15%, the pitch e of the prism pattern of the third prism pattern layer 131 formed on the first surface 132a of the third base portion 132 is 50 μm, the height f is 25 μm, and the second diffusion layer 133 on the second surface 132b of the third base portion 132 has a haze value of 30%, the optimal incident angle θ at which the brightness near the light measurement device standard 0 degree is the highest can be formed at 73 degrees. That is, when the light passing through the lower surface of the laminate of the second sheet 120 and the third sheet 130 (for example, the other surface 122b of the second sheet 120) is incident at an angle of +73 degrees (or -73 degrees), the highest brightness value may be obtained.

[0063] In summary, the incident angle θ of light incident on the second sheet 120 can be determined according to the specifications and / or ridge direction (e.g., P2 in FIG. 1) of the multiple second prism patterns of the second prism pattern layer 121 included in the second sheet 120 and the specifications and / or ridge direction (e.g., P3) of the multiple third prism patterns of the third prism pattern layer 131 included in the third sheet 130. That is, the incident angle θ can be set in various ways according to the required specifications of the second sheet 120 and / or the third sheet 130 required for the optical film 100, but the optical film 100 of the present disclosure includes a first prism pattern layer 113 including a prism pattern on the lower surface and a pyramid pattern layer 111 including a pyramid pattern on the upper surface based on the first base portion 112, thereby forming an optical path corresponding to the optimal incident angle θ required for the optical film 100 according to some embodiments, and as a result, an optical film 100 having high brightness can be provided. Meanwhile, referring to FIG. 5b, a viewing angle Φ(phi) is shown, which may mean an angle between a virtual line drawn on one side (for example, parallel to the X-axis) from the center of the viewing angle distribution shown in FIG. 5b and the central light of the light (or light beam) emitted from the first sheet 110. The viewing angle Φ(phi) is determined by the specifications and / or ridge direction (for example, P1 in FIG. 1) of the first prism pattern layer 113 of the first sheet 110 of the light incident on the second sheet 120, and in two embodiments (Example 1-1 and Example 1-2) shown in FIG. 5b, the optimal viewing angle Φ is formed at 45 degrees. Hereinafter, the viewing angle Φ will be described in more detail through the embodiments of FIG. 6a and FIG. 6b.

[0064] According to various embodiments of the present disclosure, an optical film 100 can be provided that includes a first sheet 110 that is designed to increase the shielding performance from the direction in which light is incident, while at the same time allowing light passing through the lower surface of the laminate of the second sheet 120 and the third sheet 130 (e.g., the second surface 122b of the second sheet 120) to be incident at a specific incident light angle θ.

[0065] As shown in FIGS. 1 to 5b, an optical film 100 according to an embodiment includes a first sheet 110 including a first base portion 112, a pyramid pattern layer 111 having a plurality of pyramid patterns formed on a first surface 112a of the first base portion 112, and a first prism pattern layer 113 having a plurality of first prism patterns formed on a second surface 112b of the first base portion 112, and is disposed over the first sheet 110. A second base portion 122 and a pyramid pattern layer 111 having a plurality of first prism patterns formed on a first surface 112a of the second base portion 122 are disposed over the first sheet 110. The optical element 100 may include a second sheet 120 including a second prism pattern layer 121 having a plurality of third prism patterns formed thereon and a first diffusion layer 123 formed on the second surface 122b of the second base portion 122, and a third sheet 130 arranged over the second sheet 120, the third sheet 130 including a third base portion 132, a third prism pattern layer 131 having a plurality of third prism patterns formed thereon and a second diffusion layer 133 formed on the second surface 132b of the third base portion 132, the third sheet 130 being arranged over the second sheet 120 and including a third base portion 132, a first surface 132a of the third base portion 132, a third prism pattern layer 131 having a plurality of third prism patterns formed thereon, and a second diffusion layer 133 formed on the second surface 132b of the third base portion 132.

[0066] The liquid crystal display device 1 of Figures 1 to 5b can be manufactured in a form in which the first sheet 110, the second sheet 120, and the third sheet 130 are laminated to one another. In particular, taking into consideration the specifications of the laminated second sheet 120 and third sheet 130, by appropriately adjusting the specifications of the pyramid pattern layer 111 formed on the first surface 112a of the first base portion 112 and the first prism pattern layer 113 formed on the second surface 112b, the first sheet 110 can refract and / or reflect light at the point where it abuts against the second surface 122b of the second sheet 120 so that the light is incident at a specific incident light angle θ toward the second sheet 120 (improved brightness performance).

[0067] FIG. 6a is a diagram showing a backlight unit including a sheet on which an inverse prism pattern layer (first prism pattern layer) is formed and an edge-type light source according to a certain embodiment. FIG. 6b is a diagram showing the change in the incident angle and the viewing angle due to the change in the refractive index of the inverse prism pattern layer. Through the embodiment of FIG. 6a and FIG. 6b, it can be explained how the incident angle and the viewing angle φ shown in FIG. 5b are set according to the change in the refractive index of the inverse prism pattern layer.

[0068] According to some embodiments, as shown in FIG. 6a, a first sheet 110' may be provided in which a first prism pattern layer including a plurality of first prism patterns is formed on a second surface, except for a pyramid pattern layer including a plurality of pyramid patterns. In FIG. 6b, the item of "Outgoing Light" is measured between the light guide plate 12 and the first sheet 110' in the embodiment shown in FIG. 6a, and may represent data on optical properties of light emitted from the light guide plate 12. The items of various embodiments (Example 2-1, Example 2-2, Example 2-3) in FIG. 6b may represent data on optical properties of light measured on the first sheet 110'.

[0069] 6a and 6b, the arrangement direction (e.g., P1) of the ridges of the first prism patterns may be perpendicular to the arrangement of the light sources (e.g., arranged in a fourth direction parallel to the X-axis). According to some embodiments, as the refractive index of the prism pattern layer provided on the first sheet 110' changes, it can be confirmed that the incident angle θ on the second surface 122b of the second sheet 120 is maintained at approximately 73 degrees, and the viewing angle φ changes as the refractive index of the first prism pattern layer changes. For example, when the refractive index of the first prism pattern layer is 1.49, the incident angle on the second surface 122b of the second sheet 120 may be formed at +74 degrees (or -74 degrees), and the viewing angle may be formed at 60 degrees. Also, for example, when the refractive index of the first prism pattern layer is 1.58, the incident angle on the second surface 122b of the second sheet 120 may be formed at +72 degrees (or -72 degrees), and the viewing angle may be formed at 54 degrees. Also, for example, when the refractive index of the first prism pattern layer is 1.69, the incident angle on the second surface 122b of the second sheet 120 may be formed at +73 degrees (or -73 degrees), and the viewing angle may be formed at 53 degrees. That is, by adjusting the refractive index of the first prism pattern layer, the viewing angle φ of the light incident on the second surface 122b of the second sheet 120 can be adjusted to a desired angle. Using such a principle, the specifications of the pyramid pattern layer 111 and the first prism pattern layer 113 provided on the first sheet can be set in various ways so that the optical film 100 can exhibit optimal brightness performance.

[0070] Fig. 7 is a perspective view showing a liquid crystal display device including an optical film according to an embodiment. Fig. 8a is a diagram showing optical characteristics of a liquid crystal display device including a diffusion plate according to some embodiments. Fig. 8b is a diagram showing optical characteristics of a liquid crystal display device including an optical film according to an embodiment. Fig. 8c is a diagram showing optical characteristics of a liquid crystal display device including an optical film according to an embodiment.

[0071] According to some embodiments, as shown in FIG. 6a, a first sheet 110 can be provided, which includes a pyramid pattern layer including a plurality of pyramid patterns on a first surface and a first prism pattern layer including a plurality of first prism patterns on a second surface. For the remaining components except for the first sheet 110, the above description of FIGS. 1 to 5b can be referred to. In FIG. 8a, the "diffusion plate" item can represent optical characteristics of light measured between the optical sheet and the second sheet 120 and light measured between the third sheet 130 and the diffusion sheet 17 when an optical sheet to which light diffusing agent beads are added is placed instead of the first sheet 110 in the liquid crystal display device 1 of FIG. 7, and the data thereof (e.g., viewing angle distribution 1, viewing angle distribution 2, luminance, incident angle θ, viewing angle φ). In addition, the items of various embodiments in FIG. 8b ("Example 3-1", "Example 3-2", "Example 3-3") can represent data regarding the optical characteristics (e.g., viewing angle distribution 1, viewing angle distribution 2, brightness, incident angle θ, viewing angle φ) of light measured between the first sheet 110 and the second sheet 120 and light measured between the third sheet 130 and the diffusion sheet 17 when the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are changed in various ways. 8c ("Example 3-4", "Example 3-5", "Example 3-6") may represent data (e.g., viewing angle distribution 1, viewing angle distribution 2, luminance, incident angle θ, viewing angle φ) related to optical characteristics of light measured between the first sheet 110 and the second sheet 120 and light measured between the third sheet 130 and the diffusion sheet 17 when the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are variously changed. The viewing angle distribution 1 is intended to indicate the viewing angle for the light emitted from the first sheet 110, and may represent the distribution of light focused on a horizontal plane (e.g., a plane parallel to the XY plane) of points between the first sheet 110 and the second sheet 120.The viewing angle distribution 2 is intended to show the viewing angle for the light emitted from the entire optical film 100, and can represent the distribution of light focused on a horizontal plane (e.g., a plane parallel to the XY plane) at a point between the third sheet 130 and the diffusion sheet 17. It can be seen from Figures 8a, 8b, and 8c that the luminance, incident angle, and / or viewing angle change variously when the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are variously changed.

[0072] Looking at the items of various embodiments ("Example 3-1", "Example 3-2", "Example 3-3") in Fig. 8b, when the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are 1.58 and 1.49, respectively, as shown in Example 3-2, it can be confirmed that the brightness performance is improved by having 125.2% brightness compared to the embodiment with the diffusion sheet of Fig. 8a. Also, it can be confirmed that the brightness is increased most significantly compared to the case where the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are set as in Example 3-1 or Example 3-3.

[0073] Looking at the various embodiments ("Example 3-4", "Example 3-5", "Example 3-6") in Fig. 8c, when the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are 1.58 and 1.69, respectively, as shown in Example 3-5, it can be confirmed that the brightness performance is improved by having 120.6% brightness compared to the embodiment with the diffusion sheet in Fig. 8a. Also, it can be confirmed that the brightness is increased most significantly compared to the case where the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are set as in Example 3-4 or Example 3-6.

[0074] According to various embodiments, the refractive index difference (|Diff P-Diff PY|) between the pyramid pattern layer 111 of the first sheet 110 and the first prism pattern layer 113 can be formed to be at most 0.2 or less. Referring to Figures 8b and 8c, when the absolute value of the refractive index difference between the pyramid pattern layer 111 and the first prism pattern layer 113 is configured to be 0.2 or less, the brightness of the light emitted from the first sheet 110 can be improved.

[0075] According to various embodiments, the pyramid pattern layer 111 and the first diffusion layer 123 may be formed so that the absolute value of the difference between their refractive indices is 0.2 or less. By forming the pyramid pattern layer 111 and the first diffusion layer 123 so that the refractive index difference between them is 0.2 or less, it may be advantageous to prevent damage to the pyramid pattern 111a formed on the first sheet 110 located on the lower side when the first sheet 110 and the second sheet 120 are bonded together, and to minimize deformation of the light separation characteristics and light distribution, thereby maintaining an optimal incident angle θ incident on the second sheet 120 located on the upper side.

[0076] According to various embodiments, the refractive index difference between the second prism pattern layer 121 and the second diffusion layer 133 may be greater than 0 and less than or equal to 0.2. The difference between the refractive index between the second prism pattern layer 121 and the second diffusion layer 133 is greater than 0 and less than or equal to 0.2, so that the optical film 100 has high brightness.

[0077] As an example regarding the aforementioned refractive index, an optical film 100 (e.g., optical film 100c of FIG. 4c) including a first sheet 110, a second sheet 120, and a third sheet 130 according to an embodiment of the present disclosure may include a first sheet 110 formed with a first prism pattern layer 113 having a refractive index of 1.49 and a pyramid pattern layer 111 having a refractive index of 1.49 to 1.69, a second sheet 120 formed with a first diffusion layer 123 having a refractive index of 1.49 and a second prism pattern layer 121 having a refractive index of 1.69, and a third sheet 130 formed with a second diffusion layer 133 having a refractive index of 1.49 and a third prism pattern layer 131 having a refractive index of 1.69. According to one embodiment, the refractive index of the first prism pattern layer 113 including the inverted prism pattern can be appropriately adjusted to match the refractive index of the third prism pattern layer 131 including the topmost prism, while keeping the refractive index of the other components fixed, thereby forming an optimal incident angle θ for light entering the underside of the second sheet.

[0078] Fig. 9a is a diagram showing optical characteristics of a liquid crystal display device including an optical film according to an embodiment, Fig. 9b is a diagram showing optical characteristics of a liquid crystal display device including an optical film according to an embodiment, Fig. 9c is a diagram showing optical characteristics of a liquid crystal display device including an optical film according to an embodiment, and Fig. 9d is a diagram showing optical characteristics of a liquid crystal display device including an optical film according to an embodiment.

[0079] In the embodiment of FIGS. 9a-9d, the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are kept constant (e.g., the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are kept constant). When the ridge direction P3 of the plurality of third prism patterns included in the third prism pattern layer 131 of the third sheet 130 and the ridge direction P1 of the plurality of first prism patterns included in the first prism pattern layer 113 of the first sheet 110 are set in various ways, data on the optical characteristics of the light measured between the first sheet 110 and the second sheet 120 and the light measured between the third sheet 130 and the diffusion sheet 17 (for example, viewing angle distribution 1, viewing angle distribution 2, luminance, left / right incident angle θ, left / right viewing angle φ) can be represented. The viewing angle distribution 1 is intended to indicate the viewing angle for the light emitted from the first sheet 110, and can represent the distribution of light that is connected on a horizontal plane (for example, a plane parallel to the XY plane) of points between the first sheet 110 and the second sheet 120. The viewing angle distribution 2 is intended to show the viewing angle for the light emitted from the entire optical film 100, and can represent the distribution of light focused on a horizontal plane (e.g., a plane parallel to the XY plane) at a point between the third sheet 130 and the diffusion sheet 17. It can be seen from Figures 9a, 9b, 9c, and 9d that the luminance, left / right incident angles, and / or left / right viewing angles are variously changed when the refractive index Diff PY of the pyramid pattern layer 111 of the first sheet 110 and the refractive index Diff P of the first prism pattern layer 113 are variously changed.

[0080] Looking at the items for various embodiments in Figure 9a ("Example 4-1", "Example 4-2", "Example 4-3", and "Example 4-4"), it can be seen that when the ridge direction (P3; third direction) of the multiple third prism patterns in the third prism pattern layer 131 is perpendicular to the arrangement direction of the light sources 11 (fourth direction), and the ridge direction (P1; first direction) of the multiple first prism patterns in the first prism pattern layer 113 is also perpendicular to the arrangement direction of the light sources 11 (fourth direction) (i.e., when parallel to the third direction), the brightness is highest at 151.6%.

[0081] Looking at the items for various embodiments in Figure 9b ("Example 4-5", "Example 4-6", "Example 4-7", and "Example 4-8"), it can be seen that when the ridge direction (P3; third direction) of the multiple third prism patterns in the third prism pattern layer 131 is tilted by 75 degrees with respect to the arrangement direction of the light sources 11 (fourth direction), the brightness is highest at 148.0% when the ridge direction (P1; first direction) of the multiple first prism patterns in the first prism pattern layer 113 is tilted by 75 degrees with respect to the arrangement direction of the light sources 11 (fourth direction) (i.e., when parallel to the third direction).

[0082] Referring to various embodiments of Figure 9c ("Example 4-9", "Example 4-10", "Example 4-11", and "Example 4-12"), it can be confirmed that when the ridge direction (P3; third direction) of the multiple third prism patterns of the third prism pattern layer 131 is tilted by 60 degrees with respect to the arrangement direction of the light sources 11 (fourth direction), the brightness is highest at 132.7% when the ridge direction (P1; first direction) of the multiple first prism patterns of the first prism pattern layer 113 is tilted by 60 degrees with respect to the arrangement direction of the light sources 11 (fourth direction) (i.e., when parallel to the third direction).

[0083] Looking at the items of various embodiments in Figure 9d ("Example 4-13", "Example 4-14", "Example 4-15", and "Example 4-16"), it can be seen that when the ridge direction (P3; third direction) of the multiple third prism patterns of the third prism pattern layer 131 is tilted by 45 degrees with respect to the arrangement direction of the light sources 11 (fourth direction), the brightness is highest at 121.8% when the ridge direction (P1; first direction) of the multiple first prism patterns of the first prism pattern layer 113 is tilted by 45 degrees with respect to the arrangement direction of the light sources 11 (fourth direction) (i.e., when parallel to the third direction).

[0084] According to one embodiment, the ridge direction (P3; third direction) of the plurality of third prism patterns of the third prism pattern layer 131 is arranged so as to be tilted from the arrangement direction (fourth direction) of the light source 11, thereby preventing the moire phenomenon, while the ridge direction (P3; third direction) of the plurality of third prism patterns of the third prism pattern layer 131 and the ridge direction (P1; first direction) of the plurality of first prism patterns of the first prism pattern layer 113 are configured so as to face substantially the same direction, thereby ensuring high brightness performance. That is, according to the present disclosure, the ridge direction P1 of the plurality of first prism patterns of the first prism pattern layer 113 may be parallel to the ridge direction P3 of the plurality of third prism patterns of the third prism pattern layer 131.

[0085] According to one embodiment, not only an optical film 100 having three sheets 110, 120, 130, but also an optical film having one sheet 110 (e.g., optical film 100a in FIG. 4a) and an optical film having two sheets 110, 120 (e.g., optical film 100b in FIG. 4b) may be included within the scope of the present invention.

[0086] According to an embodiment of the present disclosure, the moire phenomenon can be prevented even with a single sheet 110 of optical film (e.g., the optical film 100a of FIG. 4a). FIG. 10a is a diagram showing the appearance of a liquid crystal panel with the arrangement of the first prism pattern layer 113 and the pyramid pattern layer 111 in the single sheet 110. FIG. 10b is a diagram showing the appearance of a liquid crystal panel with the arrangement of the first prism pattern layer 113 and the pyramid pattern layer 111 according to an embodiment.

[0087] The moire phenomenon may or may not occur easily by varying the parameter values ​​and / or pattern arrangements of the pyramid pattern 111a of the pyramid pattern layer 111 and the prism pattern of the first prism pattern layer 113.

[0088] For example, as shown in Figures 10a and 10b, when the pyramid pattern 111a of the pyramid pattern layer 111 and the prism pattern of the first prism pattern layer 113 are arranged, the moire phenomenon may or may not occur easily depending on the difference between the parameter value of the pyramid pattern 111a and the parameter value of the prism pattern (hereinafter referred to as "parameter value difference"). Here, the parameter is, for example, a parameter for length, and here, the "parameter value difference" may mean, for example, the difference between the pitch of the pyramid pattern and the pitch of the prism pattern.

[0089] According to one embodiment of the present disclosure, the pyramid pattern layer 111 includes a plurality of pyramid patterns 111a having a first pitch pi1, and the first prism pattern layer 113 (or the inverse prism pattern layer) can include a plurality of prism patterns having a second pitch pi2. Here, the first pitch pi1 of the pyramid pattern 111a can be defined as the length of the bases a1, a2. The numerical difference of the patterns can refer to the difference between the first pitch pi1 and the second pitch pi2.

[0090] On the other hand, when one base of the pyramid pattern 111a and the ridge direction of the prism pattern are not 0 degrees or 90 degrees but are inclined by a predetermined angle (for example, 30 degrees) or more, the difference in the numerical values ​​of the patterns can be compared based on the 1-1 pitch pi1-1 corresponding to the length of the diagonal of the pyramid pattern 111a, not the first pitch pi1 which is the length of the base of the pyramid pattern 111a. In the embodiment of Figures 6a and 6b, the phenomenon of moire occurring can be expressed when the length a1, a2 of the base of the pyramid pattern 111a is compared with the pitch pi2 of the prism pattern, but half the length of the diagonal of the pyramid pattern 111a, pi1-1 / 2, is compared with the pitch pi2 of the prism pattern.

[0091] For example, moire may occur in the liquid crystal panel 20 shown in FIG. 10a, and moire may not occur in the liquid crystal panel 20 shown in FIG. 10b. For example, FIG. 10a shows that the moire phenomenon occurs when the pitch pi2 of the prism pattern is 21 μm, the length of the base of the pyramid pattern is 30 μm, and half the length of the diagonal of the pyramid pattern is 21.21 μm. Also, for example, FIG. 10b shows that the moire phenomenon does not occur when the pitch pi2 of the prism pattern is 17 μm, the length of the base of the pyramid pattern is 30 μm, and half the length of the diagonal of the pyramid pattern is 21.21 μm. This makes it possible to confirm that the moire phenomenon occurs when the length of a certain parameter of the pyramid pattern (e.g., half the length of the diagonal) is similar to the length of the pitch of the prism pattern, and does not occur when they are not similar. The pitch relationship that does not cause moire in the optical film 100 can be summarized by the following formula. In order to prevent moire from occurring in the optical film 100, the following formula 1 or 2 must be satisfied.

[0092]

number

[0093]

number

[0094] In some embodiments of the present disclosure, when the pitch of a pyramid pattern and the pitch of a prism pattern are similar, "similar" can be defined as, for example, two different pitches having the same value in micrometers (μm) when the decimal point is discarded. Alternatively, "similar" can be defined as, for example, two different pitches having a difference of less than 3% of the total length of the pitch of a pattern.

[0095] The optical films of the various embodiments of the present disclosure and the backlight units including the same described above are not limited to the above-described embodiments and drawings, and it will be apparent to those having ordinary skill in the art to which the present invention pertains that various substitutions, modifications and alterations are possible within the technical scope of the present disclosure. [Explanation of symbols]

[0096] LCD display: 1 Backlight units: 10 Light source: 11 Light guide plate: 12 Reflector: 13 Diffusion sheet: 17 LCD panel: 20 Optical film: 100 1st sheet: 110 Pyramid Pattern Layer: 111 First base: 112 First prism pattern layer: 113 Second sheet: 120 Second prism pattern layer: 121 Second base: 122 First diffusion layer: 123 Third sheet: 130 Third prism pattern layer: 131 Third base: 132 Second diffusion layer: 133

Claims

1. In optical films, a first sheet including a first base portion, a pyramid pattern layer on a first surface of the first base portion, the pyramid pattern layer having a plurality of pyramid patterns each having a base length of a first pitch and a diagonal length of a 1-1 pitch, and a first prism pattern layer on a second surface of the first base portion, the pyramid pattern layer having a plurality of first prism patterns each having a base length of a second pitch; a second sheet including a second base portion, a second prism pattern layer having a plurality of second prism patterns formed on a first surface of the second base portion, and a first diffusion layer formed on the second surface of the second base portion, the first diffusion layer facing the pyramid pattern layer and disposed over the first sheet; a third base portion, a third prism pattern layer having a plurality of third prism patterns formed on a first surface of the third base portion, and a second diffusion layer formed on a second surface of the third base portion, the second diffusion layer facing the third prism pattern layer and including a third sheet disposed on the second sheet in a superimposed manner; the first prism patterns form ridges in a first direction; The plurality of pyramid patterns are configured such that an extension direction of any of the bases forms an angle between 0 degrees and 45 degrees with the first direction; the second prism patterns form ridges in a second direction perpendicular to the first direction, The optical film, wherein ridge lines of the plurality of third prism patterns extend in a third direction perpendicular to the second direction.

2. The optical film of claim 1 , wherein the second sheet and the third sheet are each manufactured in a laminated form.

3. The optical film of claim 1 , wherein the first sheet, the second sheet, and the third sheet are each manufactured in a laminated form.

4. The optical film of claim 1 , wherein the first sheet refracts or reflects light such that the light is incident at a specified angle toward the second surface of the second sheet.

5. The optical film according to claim 1 , wherein the pyramid pattern layer and the first prism pattern layer have a difference in refractive index of 0.2 or less.

6. The optical film according to claim 1 , which satisfies the following formula 1 or 2: [0010] [0025]

7. In the backlight unit, Edge type light sources, and An optical film disposed over the light source, a first sheet including a first base portion, a pyramid pattern layer on a first surface of the first base portion, the pyramid pattern layer having a plurality of pyramid patterns each having a base length of a first pitch and a diagonal length of a 1-1 pitch, and a first prism pattern layer on a second surface of the first base portion, the pyramid pattern layer having a plurality of first prism patterns each having a base length of a second pitch; a second sheet including a second base portion, a second prism pattern layer having a plurality of second prism patterns formed on a first surface of the second base portion, and a first diffusion layer formed on the second surface of the second base portion, the first diffusion layer facing the pyramid pattern layer and disposed over the first sheet; a third base portion, a third prism pattern layer having a plurality of third prism patterns formed on a first surface of the third base portion, and a second diffusion layer formed on a second surface of the third base portion, the second diffusion layer facing the third prism pattern layer and including a third sheet disposed on the second sheet in a superimposed manner; the first prism patterns form ridges in a first direction; The plurality of pyramid patterns have an extension direction of any of the bases that forms an angle with the first direction within a range of 0 degrees to 45 degrees, the second prism patterns form ridges in a second direction perpendicular to the first direction, the ridge lines of the third prism patterns extend in a third direction perpendicular to the second direction.

8. The backlight unit according to claim 7 , wherein the edge-type light source is arranged in a fourth direction perpendicular to the first direction and configured to emit light in a direction parallel to the first direction.

9. the edge-type light source is disposed in a fourth direction; 8. The backlight unit of claim 7, wherein the first direction is tilted from the fourth direction by a first angle difference, and the third direction is formed parallel to the first direction and tilted from the fourth direction by a second angle difference equal to the first angle difference.

10. The backlight unit according to claim 7 , which satisfies the following formula 1 or 2: [0030] [0045]

11. In optical films, a pyramid pattern layer on a first surface of the first base portion, the pyramid pattern layer having a plurality of pyramid patterns each having a base length of a first pitch and a diagonal length of a 1-1 pitch; and a first prism pattern layer on a second surface of the first base portion, the pyramid pattern layer having a plurality of prism patterns each having a base length of a second pitch; the first prism patterns form ridges in a first direction; An optical film, wherein the extending direction of any of the bases of the plurality of pyramid patterns forms an angle of 0 degrees or more and 45 degrees or less with the first direction.

12. The optical film according to claim 11 , wherein the pyramid pattern layer and the first prism pattern layer have a difference in refractive index of 0.2 or less.

13. The optical film according to claim 11 , which satisfies the following formula 1 or 2: [0050] [006]

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