Optical film and backlight unit including the same

Abstract

A backlight unit and an optical film are disclosed. The backlight unit includes: a light source; a color changer for changing the color of light emitted from the light source; and at least one optical film disposed on the color changer. The at least one optical film includes: a first sheet comprising: a first substrate; a first pattern layer having a plurality of pyramidal patterns on one side of the first substrate; a second pattern layer disposed on the other side of the first substrate and having a pattern different from the plurality of pyramidal patterns; a second sheet comprising: a second substrate; a third pattern layer having a plurality of pyramidal patterns on one side of the second substrate; and a fourth pattern layer disposed on the other side of the second substrate and having a pattern corresponding to the pattern of the second pattern layer. The patterns of the second pattern layer and the fourth pattern layer include a plurality of irregular protrusions. The second pattern layer includes an adhesive material, and the plurality of protrusions of the second pattern layer are adhered to the plurality of pyramidal patterns of the third pattern layer to laminate the first sheet and the second sheet.

Description

Technical Field

[0001] Various embodiments of this disclosure relate to optical films and backlight units including therein. Background Technology

[0002] Typically, an LCD (liquid crystal display) includes a backlight unit that uniformly illuminates the entire screen of an electronic device. Backlight units are classified into edge-type and direct-lit types based on the position of the light source. Edge-type backlights are located on the side of the substrate including the display surface and require a light guide plate to convert the linear light from the lamp into surface light. Direct-lit backlights are located below the substrate including the display surface and do not require a light guide plate. Direct-lit backlight units have high light utilization efficiency, simple structure, and no limitations on substrate size, therefore they are widely used in common LCD devices. A typical direct-lit backlight unit includes a light source, a diffuser, and an optical film including prisms. Light emitted from the light source is diffused by the diffuser and then transmitted to the liquid crystal panel through the upper optical film.

[0003] Liquid crystal display devices are actively using miniature LEDs (light emitting diodes) and / or micro-LEDs as light sources, which offer advantages such as miniaturization, lightweight design, and / or low power consumption. Miniature LEDs or micro-LEDs can be individual chips forming separate pixels or light sources, thus eliminating limitations on the size and shape of the display and enabling sharper image quality compared to conventional light sources.

[0004] As LED chips become smaller, research is also actively being conducted on backlight units to enhance the light characteristics of LEDs.

[0005] Direct-lit backlight units that use mini-LEDs or micro-LEDs as light sources can use diffusers that transform point light sources into surface light sources. Since direct-lit backlight units arrange the light source on a plane, to prevent the shape of the light source (e.g., the shape of a mini-LED or micro-LED) from being recognized by the LCD panel, they can have thick diffusers or a structure with multiple diffusers stacked on top of each other.

[0006] According to one embodiment, the diffuser sheet may additionally or substantially include a shielding sheet for shielding hot spots that are recognized by the liquid crystal panel as the shape of the light source.

[0007] In order to provide shielding performance that prevents the shape of the light source from being recognized by the liquid crystal panel, the shielding sheet (and / or diffuser sheet) needs to be made relatively thick, which may limit the thinning of the liquid crystal display device. Conversely, if the shielding sheet is made too thick, it may cause a significant decrease in the brightness of the liquid crystal display device. As mentioned above, in a backlight unit equipped with the shielding sheet, the thickness of the shielding sheet can be related to both shielding performance and brightness performance, and there can be a trade-off between these two performances. Summary of the Invention

[0008] The present invention provides, through various embodiments, an optical film for a liquid crystal display device that has excellent shielding performance (hereinafter referred to as "shielding performance") and high brightness (hereinafter referred to as "brightness performance"), even without using a thick diffuser sheet.

[0009] The backlight unit disclosed in various embodiments may include: a light source; a color changer for changing the color of light emitted from the light source; and at least one optical film disposed on the color changer. The at least one optical film may include: a first sheet comprising: a first substrate; a first pattern layer having a plurality of pyramidal patterns on one side of the first substrate; a second pattern layer disposed on the other side of the first substrate and having a pattern different from the plurality of pyramidal patterns; a second sheet comprising: a second substrate; a third pattern layer having a plurality of pyramidal patterns on one side of the second substrate; and a fourth pattern layer disposed on the other side of the second substrate and having a pattern corresponding to the pattern of the second pattern layer. The patterns of the second pattern layer and the fourth pattern layer may include a plurality of irregular protrusions. The second pattern layer may include an adhesive material, wherein the plurality of protrusions of the second pattern layer are adhered to the plurality of pyramidal patterns of the third pattern layer, thereby laminating the first sheet and the second sheet.

[0010] The optical film disclosed in various embodiments may include: a first sheet comprising: a first substrate; a first patterned layer having a plurality of pyramidal patterns on one side of the first substrate; and a second patterned layer disposed on the other side of the first substrate and having a pattern different from the plurality of pyramidal patterns; and a second sheet comprising: a second substrate; a third patterned layer having a plurality of pyramidal patterns on one side of the second substrate; and a fourth patterned layer disposed on the other side of the second substrate and having a pattern corresponding to the pattern of the second patterned layer. The patterns of the second patterned layer and the fourth patterned layer may include a plurality of irregular protrusions. The second patterned layer may include an adhesive material, and the second patterned layer and the third patterned layer may be bonded to each other, thereby laminating the first sheet and the second sheet.

[0011] (Invention Effects)

[0012] According to various embodiments of this disclosure, the backlight unit does not have a thick diffuser sheet, which can help to make the backlight unit thinner.

[0013] According to various embodiments of the present disclosure, an optical film with excellent shielding and brightness performance for mini LEDs or micro LEDs, and a backlight unit including the film, can be provided.

[0014] The effects that can be obtained in this disclosure are not limited to those mentioned above, and those skilled in the art should be able to clearly understand other effects not mentioned from the following description. Attached Figure Description

[0015] Figure 1 This diagram illustrates various embodiments of a liquid crystal display device including a diffuser sheet, according to the present disclosure.

[0016] Figure 2 This diagram illustrates various embodiments of the present disclosure, including a backlight unit comprising multiple laminated optical films and a liquid crystal display device including the backlight unit.

[0017] Figure 3 This is a side view illustrating an optical film with multiple laminated sheets according to various embodiments of the present disclosure.

[0018] Figure 4 This is a perspective view illustrating an optical film laminated with multiple sheets according to various embodiments of the present disclosure.

[0019] Figure 5a This is a diagram illustrating the plurality of sheets included in the optical films involved in various embodiments of this disclosure.

[0020] Figure 5bThis is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the apex of the pyramid pattern in various embodiments of this disclosure.

[0021] Figure 5c This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the apex of the pyramid pattern in various embodiments of this disclosure.

[0022] Figure 6a This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the density of the rough pattern in various embodiments of this disclosure.

[0023] Figure 6b This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the density of the rough pattern in various embodiments of the present disclosure.

[0024] Figure 7a and Figure 7b This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the diameter of the rough pattern in various embodiments of this disclosure.

[0025] Figure 7c This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the diameter of the rough pattern in various embodiments of this disclosure.

[0026] Figure 8a This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the aspect ratio of the rough pattern in various embodiments of this disclosure.

[0027] Figure 8b This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the aspect ratio of the rough pattern in various embodiments of this disclosure.

[0028] Figure 9a This is a schematic diagram of a rough pattern of a haze-related optical film according to various embodiments of this disclosure.

[0029] Figure 9b This is a graph representing the brightness and / or shielding correlation of the optical film involved in various embodiments of this disclosure relative to the haze of a rough pattern.

[0030] Figure 9c This is a diagram used to illustrate the shielding effect related to the rough pattern of the optical film in various embodiments of this disclosure.

[0031] Figure 10a This is an illustration of a portion of a pattern in a rough pattern layer, representing an embodiment of this disclosure.

[0032] Figure 10bThis is an image of a portion of a pattern of a rough pattern layer that is enlarged according to other embodiments of this disclosure.

[0033] Figure 10c This is a diagram of a portion of a pattern in a rough pattern layer that is enlarged according to another embodiment of this disclosure.

[0034] Figure 10d This is a diagram of a portion of a pattern in a rough pattern layer that is enlarged according to another embodiment of this disclosure.

[0035] Figure 10e This is a diagram of a portion of a pattern in a rough pattern layer that is enlarged according to another embodiment of this disclosure.

[0036] Figure 11a and Figure 11b This is a diagram illustrating the optical properties of the optical films involved in various embodiments of this disclosure. Detailed Implementation

[0037] The various embodiments described herein and the terminology used therein are not intended to limit the technical features described herein to specific embodiments, and should be understood to include various modifications, equivalents, or substitutions of the corresponding embodiments. In connection with the description of the drawings, similar symbols may be used for similar or associated constituent elements. The singular form of the noun corresponding to a component may include one or more of the said components in the relevant context unless otherwise clearly specified.

[0038] According to various embodiments, each of the constituent elements described above (e.g., modules or programs) may include one or more individuals, and a portion of the multiple individuals may be separately configured in other constituent elements. According to various embodiments, among the aforementioned corresponding constituent elements, one or more constituent elements or operations may be omitted, or one or more other constituent elements or operations may be added. Generally or further, multiple constituent elements (e.g., modules or programs) may be unified into one constituent element. In this case, the unified constituent element may perform one or more functions of the constituent elements of the multiple constituent elements in the same or similar manner as they were performed by the corresponding constituent elements of the multiple constituent elements before unification. According to various embodiments, operations performed by modules, programs, or other constituent elements may be performed sequentially, in parallel, repeatedly, or inducedly, or one or more of the operations may be performed in a different order or omitted, or one or more other operations may be added.

[0039] The embodiments are described with reference to the accompanying drawings. In describing the corresponding embodiments, the same names and symbols are used for the same components, and additional descriptions thereof are omitted. Furthermore, it should be stated firstly that in describing the embodiments of the present invention, the same names and symbols are used for components having the same function, and they are substantially different from the prior art.

[0040] According to various embodiments, terms such as "including" or "having" are used to refer to the presence of features, figures, steps, operations, constituent elements, components, or combinations thereof described in the specification, and do not preclude the existence or additional possibilities of one or more other features, figures, steps, operations, constituent elements, components, or combinations thereof.

[0041] Figure 1 This diagram illustrates various embodiments of a liquid crystal display device including a diffuser sheet, according to the present disclosure.

[0042] Reference Figure 1 The 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 be disposed facing the back surface of the liquid crystal panel 20 (the surface facing the -Z direction) to diffuse light onto the liquid crystal panel 20. The backlight unit 10 may include a substrate 11 having a light source 11a, a color conversion sheet 13, diffusers 14 and 17, and prism sheets 15 and 16. Although not shown, the backlight unit 10 may also include a reflective polarizer.

[0043] According to various embodiments, the light source 11a is configured to radiate light toward the back side of the liquid crystal panel 20 and can be disposed on one side of the substrate 11. The light source 11a can be equivalent to a light emitting diode (LED). The light source 11a may include, for example, multiple LED chips 11a for radiating light. LEDs can be classified according to the size of the LED chip as large LEDs (chip size: 1000 μm or more), medium LEDs (chip size: 300-500 μm), small LEDs (chip size: 200-300 μm), mini LEDs (chip size: 100-200 μm), and micro LEDs (chip size: less than 100 μm). Here, the LED may include materials such as InGaN and GaN. The light emitted from the light source 11a can radiate toward the liquid crystal panel 20 in the Z direction. The light emitted from the light source 11a can pass through the color changer 13 and be incident on the diffuser 14.

[0044] According to various embodiments, a reflective sheet 12 can be formed on the surface of the substrate 11. The reflective sheet 12 may include materials such as BaSO4, TiO2, CaCo3, SiO2, Ca3(SO4)2, or materials such as Ag, and can be coated or brushed onto the substrate 11 between the light sources 11a. The reflective sheet 12 can allow light emitted from the light source 11a to pass through the color change sheet 13, diffuser sheets 14, 17, and prism sheets 15, 16, while simultaneously reflecting light reflected to the substrate 11 side due to interface reflection, etc., back to the direction of light divergence. This minimizes light loss. In other words, the reflective sheet 12 can perform light recycling.

[0045] According to various embodiments, the color converter 13 can change the color of the light emitted from the light source 11a. For example, the light from a miniature LED or micro-LED can be blue light (450nm). In this case, it is necessary to convert the blue light into white light. The color converter 13 can convert the blue light emitted from the light source 11a into white light while allowing the blue light to pass through.

[0046] According to various embodiments, diffuser sheets 14 and 17 can uniformly disperse light incident from color changer 13. Diffuser sheets 14 and 17 can be coated with a solution of a curing resin (e.g., a substance selected alone or in combination from at least one of urethane acrylates, epoxy acrylates, acrylates, and free radical generating monomers) to induce light diffusion through the light diffusing agent beads. Furthermore, diffuser sheets 14 and 17 can also be formed with protrusions (or protrusions) of uniform or non-uniform size and shape (e.g., spherical) to promote light diffusion.

[0047] According to various embodiments, diffusers 14 and 17 may include a lower diffuser 14 and an upper diffuser 17. The lower diffuser 14 may be disposed between the color conversion sheet 13 and the prism sheet 15, and the upper diffuser 17 may be disposed between the prism sheet 16 and the liquid crystal panel 20. Assuming that the backlight unit 10 also includes a reflective polarizer, the upper diffuser 17 may be disposed between the prism sheet 16 and the reflective polarizer.

[0048] According to various embodiments, prism sheets 15 and 16 can utilize optical patterns formed on their surfaces to converge incident light and then emit it onto the liquid crystal panel 20. Prism sheets 15 and 16 may include a light-transmitting substrate and a prism pattern layer formed on the upper surface (facing the +Z axis direction) of the substrate. The prism pattern layer may be formed from an optical pattern layer in the form of a triangular array with tilted surfaces at a specified angle (e.g., a 45° tilt) to improve brightness in the surface direction. The prism pattern of the prism pattern layer may be in the shape of a triangular prism, configured such that one face of the prism faces the substrate.

[0049] According to one embodiment, prism sheets 15 and 16 may include a first prism sheet 15 and a second prism sheet 16, thereby forming a composite prism sheet structure. Here, the second prism sheet 16 may be overlapped on the upper surface of the first prism sheet 15. In the first prism sheet 15, multiple first prism patterns may be arranged side-by-side. Each first prism pattern may be a structure extending in one direction. For example, the vertex line 15a of each first prism pattern may extend in a direction oriented towards the X-axis. Similarly, in the second prism sheet 16, multiple second prism patterns may also be arranged side-by-side. Each second prism pattern may be a structure extending in one direction. For example, the vertex line 16a of each second prism pattern may extend in a direction perpendicular to the X-axis and Z-axis (hereinafter referred to as the "Y-axis," see reference). Figure 4 For ease of explanation, the extension directions of the first prism pattern and the second prism pattern are shown oriented toward the X-axis and Y-axis, respectively. However, the embodiments illustrated are not limited to those shown, and the prism patterns may also be oriented in directions other than the X-axis or Y-axis.

[0050] According to various embodiments, a reflective polarizer (not shown) can be disposed above the prism sheets 15, 16 and the upper diffuser 17, thereby allowing a portion of the light focused by the prism sheets 15, 16 and diffused by the upper diffuser 17 to pass through while reflecting the rest of the light to the lower part.

[0051] According to various embodiments, the liquid crystal panel 20 can refract light emitted from the light source 11a into a predetermined pattern based on an electrical signal. The refracted light can form an image by using color filters and polarizing filters disposed on the front surface of the liquid crystal panel 20.

[0052] Figure 2 This diagram illustrates various embodiments of the present disclosure, including a backlight unit comprising multiple laminated optical films and a liquid crystal display device including the backlight unit.

[0053] Reference Figure 2An embodiment of the liquid crystal display device (or LCD (liquid crystal display) device) 1 disclosed herein may include a backlight unit 10 and a liquid crystal panel 20. The backlight unit 10 may include a substrate 11 having a light source 11a, a color conversion sheet 13, a first optical film 100, prism sheets 15 and 16, and a diffuser sheet 17. According to one embodiment, a reflective sheet 12 may be formed on one side of the substrate 11.

[0054] According to one embodiment, the backlight unit 10 may omit at least one of these components (e.g., diffuser 17) or add one or more other components (e.g., reflective polarizer (not shown)). Hereinafter, references to... Figure 1 Explanation of repeated parts.

[0055] The liquid crystal display device 1 disclosed herein is characterized by providing at least one optical film formed by a lamination structure. Here, the at least one optical film may replace the lower diffuser 14, or the at least one optical film may be provided in addition to the lower diffuser 14. The following description of the accompanying drawings of this disclosure will illustrate the case where at least one optical film is provided on one side instead of the lower diffuser 14.

[0056] In this disclosure, "optical film" can refer to a form having a diffuser sheet having a first pattern on one side of a light-transmitting substrate (hereinafter referred to as "substrate") and a diffuser sheet having a second pattern on the other side of the substrate, and the two diffuser sheets being laminated together. According to one embodiment, at least one optical film may comprise a structure in which two optical films are stacked together. However, it is not limited to this; depending on the circumstances, it may comprise three or more optical films. For ease of explanation, although... Figure 2 The image is somewhat exaggerated, but in reality, it is formed by laminating two very thin sheets 110 and 120 to form the first optical film 100.

[0057] In this disclosure, "lamination" can refer to a situation where at least one of the two sheets is bonded together by providing an adhesive. For example, it can mean that at least a portion of the sheets (e.g., a patterned layer) includes an adhesive material and the patterned layer itself can be adhesive, thereby bonding multiple sheets together to achieve integration. The laminated optical film can provide a thinner backlight unit with superior shielding performance compared to embodiments where it is simply stacked without lamination.

[0058] According to various embodiments of this disclosure, two diffuser sheets 110 and 120 form an optical film. The first sheet 110 and the second sheet 120 may each have a substrate thickness of about 100 μm or less and are laminated together to form a first optical film 100. The first optical film 100 of this disclosure is located on the color change sheet 13. The first optical film 100 may replace the lower diffuser sheet 14, or the lower diffuser sheet 14 may further include the first optical film 100.

[0059] The first optical film 100 (hereinafter, referred to simply as "laminated optical film") involved in various embodiments of this disclosure can have a thinner profile by several μm or more, while also exhibiting high rigidity and excellent shielding performance, compared to embodiments in which two or three sheets with a thickness of approximately 100 μm or approximately 160 μm are simply stacked (hereinafter, referred to simply as "unlaminated optical film"). For example, according to simulation results conducted by the applicant, the optical film in the prior art with three different diffuser sheets in an unlaminated profile has a thickness of approximately 330 μm to 490 μm, while the laminated optical film (e.g., four diffuser sheets) has a thickness of approximately 460 μm to 510 μm. Compared to a single diffuser sheet, it has a thinner profile while maintaining corresponding brightness or providing excellent performance values.

[0060] Figure 3 This is a side view illustrating an optical film with multiple laminated sheets according to various embodiments of the present disclosure.

[0061] Figure 4 This is a perspective view illustrating an optical film laminated with multiple sheets according to various embodiments of the present disclosure.

[0062] In this disclosure, the backlight unit (e.g., Figure 1 , Figure 2 The backlight unit 10 may include a first optical film 100. The first optical film 100 may include a first sheet 110 and a second sheet 120 laminated with the first sheet 110.

[0063] According to one embodiment, the first sheet 110 of the first optical film 100 may include a first substrate 112. The first sheet 110 may include a first pattern layer 111 including a first pattern on one side of the first substrate 112 and a second pattern layer 113 disposed on the other side of the first substrate 112 and including a second pattern different from the first pattern. The second sheet 120 of the first optical film 100 may include a second substrate 122. The second sheet 120 may include a third pattern layer 121 including a third pattern on one side of the second substrate 122 and a fourth pattern layer 123 disposed on the other side of the second substrate 122 and including a fourth pattern different from the third pattern.

[0064] According to one embodiment, the first sheet 110 and the second sheet 120 of the first optical film 100 can be corresponding structures. For example, the pattern structure of the first pattern layer 111 of the first sheet 110 and the pattern structure of the third pattern layer 121 of the second sheet 120 can be the same as or similar to each other. As another example, the pattern structure of the second pattern layer 113 of the first sheet 110 and the pattern structure of the fourth pattern layer 123 of the second sheet 120 can be the same as or similar to each other.

[0065] According to one embodiment, the first substrate 112 and the second substrate 122 may have corresponding thicknesses. For example, the first substrate 112 and the second substrate 122 may have a thickness of about 100 μm or less. For example, the thickness of the first substrate 112 and / or the second substrate 122 may be any one of about 38 μm, 50 μm, or 75 μm. However, the thickness of the first substrate 112 and the second substrate 122 is not limited to the examples described, and can be designed and modified in various ways to suit the thickness of supporting multiple patterned layers. According to other embodiments, the thickness of the second substrate 122 may be formed to be thicker than the thickness of the first substrate 112. For example, if the thickness of the substrate is thin, it may be damaged by the heat generated by the light source 11a, resulting in a bulging phenomenon (flattening). Therefore, the thickness of the second substrate 122 near the light source 11a may be formed to be thicker than the thickness of the first substrate 112, thereby preventing the bulging phenomenon and improving the reliability of the product.

[0066] According to one embodiment, the brightness performance of the first optical film 100 can be improved by utilizing the refractive index of each layer. In the first optical film 100, the pattern structures of the first pattern layer 111 and the third pattern layer 121 correspond to each other, thereby forming corresponding refractive indices. For example, the refractive indices of the first pattern layer 111 and the third pattern layer 121 can be formed to be approximately 1.47 to 1.70, respectively. As another example, the refractive indices of the first pattern layer 111 and the third pattern layer 121 can be formed to be approximately 1.65, respectively. In the first optical film 100, the pattern structures of the second pattern layer 113 and the fourth pattern layer 123 correspond to each other, thereby forming corresponding refractive indices. For example, the refractive indices of the second pattern layer 113 and the fourth pattern layer 123 can be formed to be approximately 1.45 to 1.55, respectively. As another example, the refractive indices of the second pattern layer 113 and the fourth pattern layer 123 can be formed to be approximately 1.49, respectively. According to one embodiment, when the second pattern layer 113 is coated with an adhesive material, the refractive index can be approximately 1.51.

[0067] Figure 5a This is a diagram illustrating the plurality of sheets included in the optical films involved in various embodiments of this disclosure.

[0068] Figure 5bThis is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the apex of the pyramid pattern in various embodiments of this disclosure.

[0069] Figure 5c This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the apex of the pyramid pattern in various embodiments of this disclosure.

[0070] In this disclosure, the backlight unit (e.g., Figure 1 , Figure 2 The backlight unit 10 may include a first optical film 100. The first optical film 100 may include a first sheet 110 and a second sheet 120 laminated with the first sheet 110. Figure 5a , Figure 5b and Figure 5c The composition of the first piece 110 and the second piece 120 can be compared with... Figure 3 and Figure 4 The first piece 110 and the second piece 120 have some or all of the same composition.

[0071] In essence, the first sheet 110 and the second sheet 120 can be laminated together to form a single film, but for ease of explanation, in Figure 5a It was made public by separating it into the first piece 110 and the second piece 120.

[0072] According to various embodiments, the first sheet 110 may include a first base 112, a first pattern layer 111 disposed on one side of the first base 112 and having a first pattern, and a second pattern layer 113 disposed on the other side of the first base 112 and having a second pattern. The first pattern layer 111 may be disposed on the surface of the first base 112 facing the +Z-axis direction, and the second pattern layer 113 may be disposed on the surface of the first base 112 facing the -Z-axis direction. The second sheet 120 may include a second base 122, a third pattern layer 121 disposed on one side of the second base 122 and having a third pattern, and a fourth pattern layer 123 disposed on the other side of the second base 122 and having a fourth pattern. The third pattern layer 121 may be disposed on the surface of the second base 122 facing the +Z-axis direction, and the fourth pattern layer 123 may be disposed on the surface of the second base 122 facing the -Z-axis direction.

[0073] According to one embodiment, the first substrate 112 and / or the second substrate 122 may be a configuration for supporting the patterned layer. For example, the first substrate 112 and / or the second substrate 122 may be formed of at least one of a transparent material capable of transmitting light, such as polycarbonate, polysulfone, polyacrylate, polystyrene, polyvinyl chloride, polyvinyl alcohol, polynorbornene, or polyester. As a specific example, the first substrate 112 may be formed of at least one of polyethylene terephthalate or polyethylene naphthalate.

[0074] According to various embodiments, the first pattern layer 111 and the third pattern layer 121 may be corresponding structures. The first pattern layer 111 and / or the third pattern layer 121 may include multiple pyramid patterns having multiple rows in a first direction and multiple columns in a second direction perpendicular to the first direction. The cross-section of each of the multiple pyramid patterns may be triangular or trapezoidal. The multiple pyramid patterns may be designed to be oblique patterns when viewed from above the first pattern layer 111 and / or the third pattern layer 121 (viewed towards the -Z axis). The multiple pyramid patterns may be designed to gradually increase in size towards the -Z axis.

[0075] According to various embodiments, the first sheet 110 and the second sheet 120 can each have a patterned layer on one side and the other side, i.e., on both sides, based on their respective bases. This, in addition to the light diffusion effect, can also increase the effect of reducing light interference and color unevenness. Each patterned layer is coated with a UV (ultra violet) curable resin solution on one side (or the other side) of the substrate and cured by irradiation with light, thereby achieving micro-patterning.

[0076] According to various embodiments, in association with the light diffusion effect, light incident beneath the second sheet 120 (e.g., the fourth pattern layer 123) can be diffused by a plurality of pyramidal patterns formed in the third pattern layer 121 of the second sheet 120. The diffused light can also be incident beneath the first sheet 110 (e.g., the second pattern layer 113), and this light can be diffused by a plurality of pyramidal patterns formed in the first pattern layer 111 of the first sheet 110. In this process, light loss and brightness reduction can be minimized through refracted light refracted at the interfaces of the pyramidal patterns, reflected light caused by interface reflection, etc. The plurality of pyramidal patterns formed in the first pattern layer 111 and the third pattern layer 121 can include a plurality (e.g., M×N) pyramids, forming a pyramidal pattern with M rows and N columns such that at least a portion overlaps with the light source 11a formed on the substrate 11.

[0077] According to various embodiments, the first sheet 110 may include a first pattern layer 111 having a pyramid pattern formed with a predetermined height (or thickness) a and a spacing b. The second sheet 120 may include a third pattern layer 121 having a pyramid pattern formed with a predetermined height (or thickness) c and a spacing d. According to one embodiment, in the first pattern layer 111, the height a and spacing b of the pyramid pattern may be defined based on a first vertices angle θ1. In the third pattern layer 121, the height c and spacing d of the pyramid pattern may be defined based on a second vertices angle θ2. Hereinafter, the first vertices angle θ1 will be described, but this description can also be applied to the second vertices angle θ2.

[0078] According to one embodiment, the first vertex angle θ1 and / or the second vertex angle θ2 can be defined by the angle between two opposing faces of the four faces forming a pyramid pattern with a trapezoidal cross-section. For example, the first vertex angle θ1 and / or the second vertex angle θ2 can be defined within the range of 70° to 150°.

[0079] According to various embodiments, when the first vertices θ1 are approximately 90 degrees (e.g., 87 to 93 degrees, denoted by "D" in the figures) and the second vertices θ2 are approximately 90 degrees (e.g., 87 to 93 degrees), the efficiency of luminance (e.g., center illuminance ratio) and shielding (e.g., shielding ratio) can be improved. See also... Figure 5b and Figure 5c(In the accompanying drawings, "PY" represents a pyramid pattern.) Experiments were conducted by differentiating the first apex angle θ1 of the first pattern layer 111 and the second apex angle θ2 of the third pattern layer 121 to confirm the effects of brightness (e.g., center illuminance ratio) and shielding (e.g., shielding ratio). In Experiment #1, the first apex angle θ1 was set to approximately 85 degrees, and the second apex angle θ2 was set to approximately 85 degrees (i.e., 85D × 2ea). In Experiment #2, the first apex angle θ1 was set to approximately 85 degrees, and the second apex angle θ2 was set to approximately 90 degrees. In Experiment #3, the first apex angle θ1 was set to approximately 90 degrees, and the second apex angle θ2 was set to approximately 90 degrees (i.e., 90D × 2ea). In Experiment #4, the first apex angle θ1 was set to approximately 95 degrees, and the second apex angle θ2 was set to approximately 90 degrees. In Experiment #5, the first vertex angle θ1 was set to approximately 95 degrees, and the second vertex angle θ2 was set to approximately 95 degrees (i.e., 95D × 2ea). After setting the center illuminance ratio and shielding ratio of Experiment #3 to 100% of the reference value, the values ​​of the center illuminance ratio and shielding ratio of Experiments #1, #2, #4, and #5 were compared.

[0080] Referring to experiments #1, #2, #3, #4, and #5, in experiments #1 and #2, comparisons with the reference values ​​confirm that the decrease in contrast brightness (center illuminance ratio) indicates insufficient improvement in shielding effectiveness. Furthermore, in experiments #4 and #5, comparisons with the reference values ​​confirm that the increase in contrast brightness (center illuminance ratio) indicates an excessive decrease in shielding effectiveness. Therefore, it can be confirmed that experiment #3 (where the first vertex angle θ1 is approximately 90 degrees and the second vertex angle θ2 is approximately 90 degrees) demonstrates the highest relative efficiency in both brightness (center illuminance ratio) and shielding (shielding ratio).

[0081] Figure 6a This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the density of the rough pattern in various embodiments of this disclosure.

[0082] Figure 6b This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the density of the rough pattern in various embodiments of the present disclosure.

[0083] In this disclosure, the backlight unit (e.g., Figure 1 , Figure 2 The backlight unit 10 may include a first optical film (e.g., Figure 5a The first optical film 100 may include a first sheet (e.g., Figure 5a The first sheet 110) and the second sheet laminated with the first sheet 110 (e.g., Figure 5a The second piece (120). Figure 6a and Figure 6bThe composition of the first piece 110 and the second piece 120 can be compared with... Figures 3 to 5c The first piece 110 and the second piece 120 have some or all of the same composition.

[0084] According to various embodiments, the first sheet 110 may include a first base 112, a first pattern layer 111 disposed on one side of the first base 112 and having a first pattern, and a second pattern layer 113 disposed on the other side of the first base 112 and having a second pattern. The second sheet 120 may include a second base 122, a third pattern layer 121 disposed on one side of the second base 122 and having a third pattern, and a fourth pattern layer 123 disposed on the other side of the second base 122 and having a fourth pattern.

[0085] According to various embodiments, the second pattern layer 113 and the fourth pattern layer 123 may be corresponding structures. The second pattern layer 113 and the fourth pattern layer 123 may form a matte pattern. For example, the second pattern layer 113 and / or the fourth pattern layer 123 may have a plurality of protruding (e.g., raised) portions arranged irregularly. The plurality of protruding portions may be randomly formed relative to each other and may protrude in a downward direction.

[0086] According to one embodiment, a plurality of protrusions in the second pattern layer 113 and / or the fourth pattern layer 123 differ from those in the first pattern layer 111 and / or the third pattern layer 121 and may be directional. At least a portion of the plurality of protrusions in the second pattern layer 113 and / or the fourth pattern layer 123 may be curved. The plurality of protrusions may be designed such that at least a portion has a size that gradually decreases toward the -Z axis.

[0087] According to one embodiment, the second pattern layer 113 may include an adhesive material, and as multiple protrusions of the second pattern layer 113 are bonded to multiple pyramid patterns of the third pattern layer 121, a laminated structure of the second sheet 120 and the first sheet 110 can be provided. For example, the second pattern layer 113 may be integrally formed of an adhesive resin, thereby allowing it to be directly bonded to the third pattern layer 121 without the need for a separate adhesive layer.

[0088] According to various embodiments, when the density of the rough pattern layer (e.g., the second pattern layer 113 and / or the fourth pattern layer 123) is about 7% (e.g., 5% to 9%), the efficiency of brightness (e.g., center illuminance ratio) and shielding (e.g., shielding ratio) can be improved. The density can be defined using the area of ​​multiple protrusions over the entire area of ​​the rough pattern layer.

[0089] Reference Figure 6a and Figure 6bExperiments were conducted by fixing the first apex of the first pattern layer 111 and the second apex of the third pattern layer 121 to approximately 90 degrees, and by varying the density of the rough pattern layers in the second pattern layer 113 and / or the fourth pattern layer 123, to confirm the effectiveness of brightness (e.g., center illuminance ratio) and shielding (e.g., shielding ratio). In Experiment #1, the density of the rough pattern layer was set to approximately 0%. In Experiment #2, the density of the rough pattern layer was set to approximately 7%. In Experiment #3, the density of the rough pattern layer was set to approximately 10%. In Experiment #4, the density of the rough pattern layer was set to approximately 20%.

[0090] After setting the center illuminance ratio and shielding ratio of Experiment #2 to 100% reference values, the values ​​of the center illuminance ratio and shielding ratio of Experiments #1, #3, and #4 were compared. Referring to Experiments #1, #2, #3, and #4, in Experiment #1, a decrease in both luminance (center illuminance ratio) and shielding was confirmed by comparing with the reference values. Furthermore, in Experiments #3 and #4, a significant increase in luminance (center illuminance ratio) was observed, while the decrease in shielding was excessively large. Therefore, it can be confirmed that the efficiency of luminance (center illuminance ratio) and shielding (shielding ratio) was relatively highest in Experiment #2 (where the density of the rough pattern layer was approximately 7%).

[0091] Figure 7a and Figure 7b This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the diameter of the rough pattern in various embodiments of this disclosure.

[0092] Figure 7c This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the diameter of the rough pattern in various embodiments of this disclosure.

[0093] In this disclosure, the backlight unit (e.g., Figure 1 , Figure 2 The backlight unit 10 may include a first optical film (e.g., Figure 5a The first optical film 100 may include a first sheet (e.g., Figure 5a The first sheet 110) and the second sheet laminated with the first sheet 110 (e.g., Figure 5a The second piece (120). Figures 7a to 7c The composition of the first piece 110 and the second piece 120 can be compared with... Figures 3 to 6b The first piece 110 and the second piece 120 have some or all of the same composition.

[0094] According to various embodiments, the first sheet 110 may include a first base 112, a first pattern layer 111 disposed on one side of the first base 112 and having a first pattern, and a second pattern layer 113 disposed on the other side of the first base 112 and having a second pattern. The second sheet 120 may include a second base 122, a third pattern layer 121 disposed on one side of the second base 122 and having a third pattern, and a fourth pattern layer 123 disposed on the other side of the second base 122 and having a fourth pattern.

[0095] According to various embodiments, the second pattern layer 113 and the fourth pattern layer 123 may be corresponding structures. The second pattern layer 113 and the fourth pattern layer 123 may form a matte pattern. For example, the second pattern layer 113 and / or the fourth pattern layer 123 may have a plurality of protruding (e.g., raised) portions arranged irregularly. The plurality of protruding portions may be randomly formed relative to each other and may protrude in a downward direction.

[0096] According to various embodiments, when the diameter of the rough patterned layer (e.g., the second patterned layer 113 and / or the fourth patterned layer 123) is approximately 30 μm to 60 μm, the efficiency of brightness (e.g., center illuminance ratio) and shielding (e.g., shielding ratio) can be improved. For example, the diameter can be defined as the average of the diameters of the respective protrusions of the rough patterned layer. As another example, the diameter can be defined as the average of the dot sizes of the respective protrusions.

[0097] Reference Figure 7a , Figure 7b and Figure 7c The first apex of the first pattern layer 111 and the second apex of the third pattern layer 121 were fixed at approximately 90 degrees. The density of the rough pattern layer in the second pattern layer 113 and / or the fourth pattern layer 123 was fixed at approximately 7%. After fixing the aspect ratio of the rough pattern layer to approximately 0.33 to 0.34, experiments were conducted with different diameters of the rough pattern layer to confirm the effectiveness of brightness (e.g., center illuminance ratio) and shielding (e.g., shielding ratio). The aspect ratio of the rough pattern layer can be defined as the height of the pattern divided by the diameter of the pattern.

[0098] In Experiment #1, the average diameter of the multiple protrusions in the rough pattern layer was set to 0 (no protrusions). In Experiment #2, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 10 μm. In Experiment #3, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 20 μm. In Experiment #4, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 30 μm. In Experiment #5, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 40 μm. In Experiment #6, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 50 μm. In Experiment #7, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 60 μm. In Experiment #8, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 70 μm. In Experiment #9, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 80 μm. In Experiment #10, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 100 μm. In Experiment #11, the average diameter of the multiple protrusions in the rough pattern layer was set to approximately 130 μm. After setting the center illuminance ratio and shielding ratio of Experiment #4 to 100% of the reference value, the values ​​of the center illuminance ratio and shielding ratio of Experiments #1–#3 and #5–#11 were compared.

[0099] Referring to experiments #1 to #11, in experiment #1, a decrease in both brightness (center illuminance ratio) and shielding was confirmed by comparison with the reference values. Furthermore, in experiments #2 and #3, a significant increase in brightness (center illuminance ratio) was observed compared to the reference values, while the decrease in shielding was excessive. Similarly, in experiment #8, a significant increase in shielding was observed compared to the reference values, while the decrease in brightness (center illuminance ratio) was excessive. Furthermore, in experiments #9, #10, and #11, a significant decrease in brightness (center illuminance ratio) was observed compared to the reference values. Therefore, it can be confirmed that the efficiency of brightness (center illuminance ratio) and shielding (shielding ratio) was relatively highest in experiments #4, #5, #6, and #7 (where the diameter of the rough pattern layer is approximately 30 μm, 40 μm, 50 μm, and 60 μm, respectively).

[0100] Reference Figure 7cAs shown in Table 1 below, it can be confirmed that excellent shielding and brightness characteristics occur within a range where the ratio of the pitch of the pyramid pattern (e.g., the pyramid pattern of the first pattern layer 111 or the pyramid pattern of the third pattern layer 121) to the diameter of the rough pattern of the coarse pattern layer (e.g., the coarse pattern of the second pattern layer 113 or the coarse pattern of the fourth pattern layer 123) is approximately 30% to 60%. For example, from the viewpoint of shielding, it can be confirmed that as the diameter (size) of the coarse pattern layer increases, the shielding increases, but the brightness decreases, thus indicating that the correlation between shielding and brightness is inverse. In particular, it can be confirmed that when the diameter (size) of the coarse pattern layer is approximately 60% or more of the pitch of the pyramid pattern, the shielding increases significantly, while the brightness loss increases. Furthermore, it can be confirmed that when the diameter (size) of the coarse pattern layer is approximately 30% or less of the pitch of the pyramid pattern, the decrease in shielding increases compared to the increase in brightness.

[0101] Table 1

[0102]

[0103] Figure 8a This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the aspect ratio of the rough pattern in various embodiments of this disclosure.

[0104] Figure 8b This is a graph showing the illuminance ratio and shielding ratio of the optical film relative to the aspect ratio of the rough pattern in various embodiments of this disclosure.

[0105] In this disclosure, the backlight unit (e.g., Figure 1 , Figure 2 The backlight unit 10 may include a first optical film (e.g., Figure 5a The first optical film 100 may include a first sheet (e.g., Figure 5a The first sheet 110) and the second sheet laminated with the first sheet 110 (e.g., Figure 5a The second piece (120). Figure 8a and Figure 8b The composition of the first piece 110 and the second piece 120 can be compared with... Figures 3 to 7c The first piece 110 and the second piece 120 have some or all of the same composition.

[0106] According to various embodiments, the first sheet 110 may include a first base 112, a first pattern layer 111 disposed on one side of the first base 112 and having a first pattern, and a second pattern layer 113 disposed on the other side of the first base 112 and having a second pattern. The second sheet 120 may include a second base 122, a third pattern layer 121 disposed on one side of the second base 122 and having a third pattern, and a fourth pattern layer 123 disposed on the other side of the second base 122 and having a fourth pattern.

[0107] According to various embodiments, the second pattern layer 113 and the fourth pattern layer 123 may be corresponding structures. The second pattern layer 113 and the fourth pattern layer 123 may form a matte pattern. For example, the second pattern layer 113 and / or the fourth pattern layer 123 may have a plurality of protruding (e.g., raised) portions arranged irregularly. The plurality of protruding portions may be randomly formed relative to each other and may protrude in a downward direction.

[0108] According to various embodiments, the aspect ratio of the rough patterned layer (e.g., the second patterned layer 113 and / or the fourth patterned layer 123) is in the range of about 0.23 to 0.5, which can improve the efficiency of brightness (e.g., center illuminance ratio) and shielding (e.g., shielding ratio).

[0109] Reference Figure 8a and Figure 8b By fixing the first apex of the first pattern layer 111 and the second apex of the third pattern layer 121 to approximately 90 degrees, fixing the density of the rough pattern layer of the second pattern layer 113 and / or the fourth pattern layer 123 to approximately 7%, and fixing the diameter of the rough pattern layer (the average size of each protrusion) to approximately 30 μm, experiments were conducted with different aspect ratios of the rough pattern layer to confirm the effectiveness of brightness (e.g., center illuminance ratio) and shielding (e.g., shielding ratio). The aspect ratio of the rough pattern layer can be defined as the height of the pattern divided by the diameter of the pattern. The height of the pattern can be defined as the average height of each of the multiple protrusions of the rough pattern layer, and the diameter of the pattern can be defined as the average diameter of each of the multiple protrusions of the rough pattern layer. By fixing the diameter of the pattern, the height and aspect ratio of the pattern can be increased proportionally.

[0110] In Experiment #1, the aspect ratio of the rough pattern layer was set to 0 (e.g., the pattern height was 0). In Experiment #2, the aspect ratio of the rough pattern layer was set to approximately 0.133 (e.g., the pattern height was approximately 4 μm). In Experiment #3, the aspect ratio of the rough pattern layer was set to approximately 0.267 (e.g., the pattern height was approximately 8 μm). In Experiment #4, the aspect ratio of the rough pattern layer was set to approximately 0.333 (e.g., the pattern height was approximately 10 μm). In Experiment #5, the aspect ratio of the rough pattern layer was set to approximately 0.4 (e.g., the pattern height was approximately 12 μm). In Experiment #6, the aspect ratio of the rough pattern layer was set to approximately 0.5 (e.g., the pattern height was approximately 15 μm). After setting the center illuminance ratio and shielding ratio of Experiment #4 to 100% of the reference value, the values ​​of the center illuminance ratio and shielding ratio of Experiments #1–#3, #5, and #6 were compared.

[0111] Referring to experiments #1 to #6, in experiment #1, a decrease in luminance (center illuminance ratio) and a decrease in shielding were confirmed by comparing with the reference values. Furthermore, in experiment #2, a significant increase in luminance (center illuminance ratio) was confirmed by comparing with the reference values, while the decrease in shielding was excessive. Experiments #3, #4, #5, and #6 confirmed that the center illuminance ratio and shielding ratio were above 90% by comparing with the reference values. Within the aspect ratio range disclosed in experiments #3, #4, #5, and #6 (e.g., 0.23 to 0.5), a relative improvement in the efficiency of luminance (center illuminance ratio) and shielding (shielding ratio) was confirmed.

[0112] Referring to Table 2 below, considering the range of aspect ratios with excellent brightness and shielding ratio (e.g., the range of 0.23 to 0.5), the relationship between the diameter of the rough pattern layer and the pattern height can be confirmed.

[0113] Table 2

[0114]

[0115] For example, when the aspect ratio is 0.23, considering a rough pattern layer diameter of approximately 30 μm, the pattern height can be approximately 6.9 μm; considering a rough pattern layer diameter of approximately 60 μm, the pattern height can be approximately 13.8 μm. As another example, when the aspect ratio is 0.5, considering a rough pattern layer diameter of approximately 30 μm, the pattern height can be approximately 15 μm; considering a rough pattern layer diameter of approximately 60 μm, the pattern height can be approximately 30 μm. Therefore, the range where the center illuminance ratio and shielding ratio are above 90% can be set as follows: the aspect ratio of the rough pattern layer is approximately between 0.23 and 0.5, the pattern diameter is approximately 30 μm to 60 μm, and the pattern height is approximately 6.9 μm to 30 μm.

[0116] Figure 9a This is a schematic diagram of a rough pattern of a haze-related optical film according to various embodiments of this disclosure.

[0117] Figure 9b This is a graph representing the brightness and / or shielding correlation of the optical film involved in various embodiments of this disclosure relative to the haze of a rough pattern.

[0118] Figure 9c This is a diagram used to illustrate the shielding effect related to the rough pattern of the optical film in various embodiments of this disclosure.

[0119] Figure 10a This is an illustration of a portion of a pattern in a rough pattern layer, representing an embodiment of this disclosure.

[0120] Figure 10b This is an image of a portion of a pattern of a rough pattern layer that is enlarged according to other embodiments of this disclosure.

[0121] Figure 10c This is a diagram of a portion of a pattern in a rough pattern layer that is enlarged according to another embodiment of this disclosure.

[0122] Figure 10d This is a diagram of a portion of a pattern in a rough pattern layer that is enlarged according to another embodiment of this disclosure.

[0123] Figure 10e This is a diagram of a portion of a pattern in a rough pattern layer that is enlarged according to another embodiment of this disclosure.

[0124] In this disclosure, the backlight unit (e.g., Figure 1 , Figure 2 The backlight unit 10 may include a first optical film (e.g., Figure 5a The first optical film 100 may include a first sheet (e.g., Figure 5a The first sheet 110) and the second sheet laminated with the first sheet 110 (e.g., Figure 5aThe second piece (120). Figures 9a to 10e The composition of the first piece 110 and the second piece 120 is k- and Figures 3 to 8b The first piece 110 and the second piece 120 have some or all of the same composition.

[0125] According to various embodiments, the first sheet 110 may include a first base 112, a first pattern layer 111 disposed on one side of the first base 112 and having a first pattern, and a second pattern layer 113 disposed on the other side of the first base 112 and having a second pattern. The second sheet 120 may include a second base 122, a third pattern layer 121 disposed on one side of the second base 122 and having a third pattern, and a fourth pattern layer 123 disposed on the other side of the second base 122 and having a fourth pattern.

[0126] According to various embodiments, the second pattern layer 113 and the fourth pattern layer 123 may be corresponding structures. The second pattern layer 113 and the fourth pattern layer 123 may form a matte pattern. For example, the second pattern layer 113 and / or the fourth pattern layer 123 may have a plurality of protruding (e.g., raised) portions arranged irregularly. The plurality of protruding portions may be randomly formed relative to each other and may protrude in a downward direction.

[0127] According to various embodiments, the rough pattern layers (e.g., the second pattern layer 113 and / or the fourth pattern layer 123) can use various rough patterns with different haze Hz. For example, the type of rough pattern layer can be a first rough pattern (e.g., Matte1, see reference). Figure 9b and Figure 10a ), second coarse pattern (e.g., Matte2, see reference) Figure 9b and Figure 10b ), third coarse pattern (e.g., Matte3, see reference) Figure 9b and Figure 10c ), fourth coarse pattern (e.g., Matte4, see reference) Figure 9b and Figure 10d ) or the fifth coarse pattern (e.g., Matte5, see reference) Figure 9b and Figure 10e At least one of them.

[0128] According to one embodiment, for a rough patterned layer, the lower the haze Hz associated with the type, the better the shielding efficiency can be. (See also...) Figure 9aIn a rough patterned layer, the lower the pattern density, the more empty areas there are, excluding the multiple protrusions. Therefore, light transmitted by the retroreflection of the pyramidal pattern of the second sheet 120 can increase the amount of total internal reflection from the empty areas of the rough patterned layer of the first sheet 110. Specifically, light emitted from the pyramidal patterned layer of the second sheet 120 can pass through the protrusions of the rough patterned layer of the first sheet 110, and upon contact with areas other than the protrusions (e.g., empty areas), it is totally internally reflected, forming a light path toward the pyramidal patterned layer, thereby generating light circulation. This maintains the brightness performance of the optical film and improves shielding performance. For example, by forming protrusions in the rough patterned layer, brightness does not decrease. As another example, as the haze Hz of the rough patterned layer decreases, the amount of total internal reflection at the interface (e.g., the empty areas of the rough patterned layer) increases, the proportion of linear light emission decreases, and the overall uniformity of emitted light can increase.

[0129] According to various embodiments, when using a coarse pattern layer (e.g., a second pattern layer 113 and / or a fourth pattern layer 123) with a coarse pattern in the haze range of approximately 13% to 85%, the efficiency of shielding (e.g., shielding ratio) can be improved. See also... Figure 9b , Figure 9c Experiments were conducted using different haze Hz values ​​for the rough patterned layers, as shown in Table 3 below, to confirm the effectiveness of brightness (e.g., center illuminance ratio) and shielding (e.g., shielding efficiency). The shielding effectiveness (e.g., the shielding in Table 3) can be evaluated using a method (measuring device: Mura (surface illuminance device)) where the rough pattern of the shielding sheets (rough patterned layers (e.g., second patterned layer 113 and / or fourth patterned layer 123)) is varied in a stacked structure of a light source (e.g., LED), one or two shielding sheets (e.g., the first sheet 110 and / or the second sheet 120), a color-changing sheet, and a prism sheet, while simultaneously measuring the respective surface illuminance. For example, the shielding level can be evaluated relative to 1 (low) to 5 (high) by visually observing each surface illuminance, as described in [reference needed]. Figure 9c .

[0130] For a rough pattern layer, using a first rough pattern (e.g., Matte1) with a haze value of approximately 99%, a shielding efficiency of approximately 1.5 can be confirmed. As another example, using a second rough pattern (e.g., Matte2) with a haze value of approximately 95%, a shielding efficiency of approximately 3.5 can be confirmed. As yet another example, using a third rough pattern (e.g., Matte3) with a haze value of approximately 85%, a shielding efficiency of approximately 3.5 can be confirmed. As yet another example, using a fourth rough pattern (e.g., Matte4) with a haze value of approximately 69%, a shielding efficiency of approximately 4.0 can be confirmed. As yet another example, using a fifth rough pattern (e.g., Matte5) with a haze value of approximately 13%, a shielding efficiency of approximately 4.3 can be confirmed. The higher the shielding efficiency, the better the shielding performance; therefore, it can be confirmed that the lower the haze value, the better the shielding performance.

[0131] Table 3

[0132]

[0133] Referring again to Table 3, experiments were conducted with different aspect ratios of the rough pattern layers to confirm the effectiveness of the shielding (e.g., shielding ratio). For example, using a first rough pattern (e.g., Matte1) with an aspect ratio of approximately 0.5, a shielding ratio of approximately 1.5 was confirmed. As another example, using a second rough pattern (e.g., Matte2) with an aspect ratio of approximately 0.35, a shielding ratio of approximately 3.5 was confirmed. As yet another example, using a third rough pattern (e.g., Matte3) with an aspect ratio of approximately 0.5, a shielding ratio of approximately 3.5 was confirmed. As yet another example, using a fifth rough pattern (e.g., Matte5) with an aspect ratio of approximately 0.23, a shielding ratio of approximately 4.3 was confirmed. The higher the shielding ratio, the better the shielding performance; therefore, it can be generally confirmed that the lower the aspect ratio, the better the shielding performance.

[0134] Referring again to Table 3, experiments were conducted with varying pattern densities in the rough pattern layers to confirm the effectiveness of the shielding (e.g., shielding ratio). The shielding effect was disclosed by comparing different rough pattern layers with decreasing pattern density values, using a partial rough pattern layer (e.g., the first and second rough patterns below) with a pattern density value of 100% as a baseline. For example, using a first rough pattern (e.g., Matte1) with a pattern density value of approximately 100%, the shielding ratio was confirmed to be approximately 1.5. As another example, using a second rough pattern (e.g., Matte2) with a pattern density value of approximately 100%, the shielding ratio was confirmed to be approximately 3.5. As yet another example, using a third rough pattern (e.g., Matte3) with a pattern density value of approximately 30%, the shielding ratio was confirmed to be approximately 3.5. As yet another example, using a fifth rough pattern (e.g., Matte5) with a pattern density value of approximately 6.8%, the shielding ratio was confirmed to be approximately 4.3. The higher the shielding rate, the better the shielding can be provided. Therefore, it can be roughly confirmed that the lower the pattern density value, the better the shielding performance can be.

[0135] According to embodiments of this disclosure, it can be confirmed that the smaller the haze value, the smaller the aspect ratio value, and the smaller the pattern density value of the rough pattern layer, the greater the shielding effect (e.g., shielding ratio). It can be confirmed that the shielding effect varies depending on the combination of haze, aspect ratio, and / or pattern density values ​​of the rough pattern layer, with haze, aspect ratio, and pattern density affecting the shielding effect in that order.

[0136] Figure 11a and Figure 11b This is a diagram used to illustrate the optical properties of optical films involved in various embodiments of this disclosure.

[0137] In this disclosure, the backlight unit (e.g., Figure 1 , Figure 2 The backlight unit 10 may include a first optical film (e.g., Figure 5a The first optical film 100 may include a first sheet (e.g., Figure 5a The first sheet 110) and the second sheet laminated with the first sheet 110 (e.g., Figure 5a The second piece (120). Figure 11a and Figure 11b The first optical film 100, including the first sheet 110 and the second sheet 120, can be configured with... Figures 3 to 10e The first optical film 100, including the first piece 110 and the second piece 120, has a portion or all of the same composition.

[0138] Reference Figure 11a and Figure 11b By distinguishing between the conventional first configuration (a), the conventional second configuration (b), and the configuration (c) involved in the embodiments of this disclosure, it can be confirmed that the shielding performance is excellent. It can be confirmed that, from the viewing angle, the dark gray area closer to the center has a stronger brightness in the dark gray area at the edge.

[0139] According to one embodiment, compared to the conventional first embodiment (a) and the conventional second embodiment (b), when confirming the viewing angle distribution (measurement position ①), it can be confirmed that the emitted light from the shielding sheet (e.g., the first optical film) converges to the center for emission. Furthermore, when confirming the viewing angle distribution (measurement position ②) in a structure that stacks a shielding sheet and a lower diffuser, compared to the conventional first embodiment (a) and the conventional second embodiment (b), it can be confirmed that as the light converges to the center, the amount of linear light increases. Furthermore, in a structure that stacks a shielding sheet, a lower diffuser, and a prism sheet (e.g., ... Figure 1 , Figure 2 When confirming the viewing angle distribution (measurement position ③) in the structure of the prism sheets 15 and 16, it can be confirmed that the configuration (c) involved in this embodiment, compared with the conventional first configuration (a) and the conventional second configuration (b), averages the light distribution of the light passing through the shielding sheet, and the light converges to the center. Therefore, it can be confirmed that a relatively large amount of light emitted from the center passes through the prism sheet, which increases the retroreflection efficiency, thereby confirming that the shielding performance is improved. Furthermore, in the case of stacked shielding sheets, lower diffusers, and prism sheets (e.g., ...), ... Figure 1 , Figure 2 When confirming the viewing angle distribution (measurement position ④) in the structure of the prism sheet 15, 16) and the upper diffuser sheet, the configuration (c) involved in this embodiment, compared with the conventional first configuration (a) and the conventional second configuration (b), can confirm that the light passing through the shielding sheet has averaged the light distribution and the light converges to the center.

[0140] The optical films and backlight units including them described above in various embodiments of this disclosure are not limited to the foregoing embodiments and drawings. Those skilled in the art should be able to implement various substitutions, modifications and alterations within the technical scope of this disclosure.

Claims

1. A backlight unit, comprising: light source; A color changer, used to change the color of light emitted from the light source; as well as At least one optical film is disposed on the color conversion film. The at least one optical film includes: The first sheet includes: a first base; a first pattern layer having a plurality of pyramid patterns on one side of the first base; and a second pattern layer disposed on the other side of the first base and having a pattern different from the plurality of pyramid patterns; and The second sheet includes: a second base; a third pattern layer having a plurality of pyramid patterns on one side of the second base; and a fourth pattern layer disposed on the other side of the second base and having patterns corresponding to the patterns of the second pattern layer. The patterns in the second pattern layer and the fourth pattern layer include multiple irregular protrusions. The second pattern layer includes an adhesive material, and the plurality of protrusions of the second pattern layer are adhered to the plurality of pyramid patterns of the third pattern layer, thereby laminating the first and second sheets. The haze of the second pattern layer and the fourth pattern layer is 13% to 85%.

2. The backlight unit according to claim 1, wherein, The plurality of pyramid patterns in the first pattern layer and the plurality of pyramid patterns in the third pattern layer have multiple rows in a first direction and multiple columns in a second direction perpendicular to the first direction.

3. The backlight unit according to claim 1, wherein, The plurality of pyramid patterns in the first pattern layer are concave pyramid patterns formed by etching one side of the first base. The plurality of pyramid patterns in the third pattern layer are oblique pyramid patterns formed by etching one side of the second base.

4. The backlight unit according to claim 1, wherein, The refractive index of the first patterned layer and the refractive index of the third patterned layer are the same.

5. The backlight unit according to claim 4, wherein, The refractive index of the first patterned layer and the refractive index of the third patterned layer are formed to have values ​​of 1.47 to 1.

70.

6. The backlight unit according to claim 1, wherein, The multiple pyramid patterns each form a vertex defined by the angle between two opposing faces of the four faces of the pyramid shape. The first vertex angle of the first pattern layer is 87° to 93°, and the second vertex angle of the third pattern layer is 87° to 93°.

7. The backlight unit according to claim 6, wherein, The density of the second and fourth pattern layers, which defines the area occupied by the plurality of protrusions, is 5% to 9%.

8. The backlight unit according to claim 7, wherein, In the second and fourth pattern layers, the average diameter of each of the plurality of protrusions is between 30 µm and 60 µm.

9. The backlight unit according to claim 8, wherein, The ratio of the height of the pattern to the diameter of the pattern in the second pattern layer and the fourth pattern layer is in the range of 0.23 to 0.

5.

10. The backlight unit according to claim 8, wherein, In the second and fourth pattern layers, the average height of each of the plurality of protrusions is between 6.9 µm and 30 µm.

11. The backlight unit according to claim 1, wherein, At least a portion of the irregular protrusions in the second and fourth pattern layers have curved shapes.

12. An optical film, comprising: The first sheet includes: a first base; a first pattern layer having a plurality of pyramid patterns on one side of the first base; and a second pattern layer disposed on the other side of the first base and having a pattern different from the plurality of pyramid patterns; and The second sheet includes: a second base; a third pattern layer having a plurality of pyramid patterns on one side of the second base; and a fourth pattern layer disposed on the other side of the second base and having patterns corresponding to the patterns of the second pattern layer. The patterns in the second pattern layer and the fourth pattern layer include multiple irregular protrusions. The second patterned layer includes an adhesive material, and the second and third patterned layers are bonded together, thereby laminating the first and second sheets. The haze of the second pattern layer and the fourth pattern layer is 13% to 85%.

13. The optical film according to claim 12, wherein, The refractive index of the first patterned layer and the refractive index of the third patterned layer are the same.

14. The optical film according to claim 12, wherein, The multiple pyramid patterns each form a vertex defined by the angle between two opposing faces of the four faces of the pyramid shape. The first vertex angle of the first pattern layer is 87° to 93°, and the second vertex angle of the third pattern layer is 87° to 93°.

15. The optical film according to claim 14, wherein, The density of the second and fourth pattern layers, which defines the area occupied by the plurality of protrusions, is 5% to 9%.

16. The optical film according to claim 15, wherein, In the second and fourth pattern layers, the average diameter of each of the plurality of protrusions is between 30 µm and 60 µm.

17. The optical film according to claim 16, wherein, The ratio of the height of the pattern to the diameter of the pattern in the second pattern layer and the fourth pattern layer is in the range of 0.23 to 0.

5.

18. The optical film according to claim 16, wherein, In the second and fourth pattern layers, the average height of each of the plurality of protrusions is between 6.9 µm and 30 µm.

Images