Optical films for display devices

Abstract

The present application relates to an optical film for a display device, which includes: a base layer; a pattern layer, which is arranged on the base layer and has a repeating pattern of valleys and peaks; a plurality of first elongated scattering members, which are arranged on the upper surface of the valleys; and a covering layer, which has a shape complementary to the repeating pattern of valleys and peaks and is connected to the repeating pattern of valleys and peaks, and the first elongated scattering members are arranged between the pattern layer and the covering layer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0050863, filed on April 30, 2019, which is hereby incorporated by reference for all purposes as if fully set forth herein. Technical Field

[0003] Exemplary implementations of the present invention generally relate to an optical film and a display panel including the same, and more particularly, to an optical film including a pattern layer and a display device including the same. Background Art

[0004] With the development of multimedia technology, display devices have become increasingly important. Therefore, various types of display devices are currently used, such as liquid crystal display (LCD) devices and organic light emitting display (OLED) devices.

[0005] Among display devices, liquid crystal displays (LCDs) are one of the most widely used flat panel display devices. These devices include two substrates and a liquid crystal layer interposed between the two substrates. Electrodes for generating an electric field (such as pixel electrodes and a common electrode) are formed on the two substrates. A voltage is applied to the electrodes to form an electric field in the liquid crystal layer, thereby aligning the orientation of the liquid crystals contained in the liquid crystal layer and controlling the polarization of incident light to display an image.

[0006] When the liquid crystal display device is viewed from the side, it may have poor visibility compared to the front. To improve the visibility from the side, the liquid crystal display device may include an optical film including a high refractive index pattern layer and a low refractive index pattern layer for improving visibility.

[0007] The above information disclosed in this Background section is only for understanding the background of the present inventive concept and therefore it may contain information that does not constitute prior art. Summary of the Invention

[0008] An optical film for a display device, and a display device including the same, constructed in accordance with the principles and exemplary implementations of the present invention, can improve visibility by utilizing elongated scattering members, which can take the form of rod-shaped diffusers. For example, the rod-shaped diffusers prevent or at least inhibit the recognition of light diffraction patterns. Furthermore, the rod-shaped diffusers can improve the side viewing angle of the optical film and the display device.

[0009] Additional features of the inventive concept will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concept.

[0010] According to one or more embodiments, an optical film for a display device includes: a base layer; a pattern layer, which is disposed on the base layer and has a repeating pattern of valleys and peaks; a plurality of first elongated scattering members, which are disposed on the upper surface of the valleys; and a covering layer, which has a shape complementary to the repeating pattern of the valleys and peaks and is connected to the repeating pattern of the valleys and peaks, and the first elongated scattering members are disposed between the pattern layer and the covering layer.

[0011] Each of the peak portions may have a width equal to or greater than a width of each of the valley portions, and the pattern layer may have a refractive index higher than that of the cover layer.

[0012] The first elongated scattering member may have a longitudinal axis having a length that is different than the length of the minor axis of the first elongated scattering member.

[0013] The first elongated scattering member may include a first rod-shaped scatterer having an elliptical cross-sectional shape.

[0014] The length of the minor axis of the first elongated scattering member may be less than the width of each of the valleys.

[0015] The longitudinal axis of the first elongate scattering member may be arranged substantially parallel to the longitudinal extension of the valley.

[0016] The first elongated scattering member may have a refractive index different from a refractive index of at least one of the pattern layer and the cover layer in a direction of the longitudinal axis.

[0017] The first elongated scattering member may have a refractive index smaller than that of the pattern layer.

[0018] The optical film may further include a second elongated scattering member, and the second elongated scattering member may be disposed in a region extending from an upper surface of the peak portion to an upper surface of the cover layer.

[0019] The second elongate scattering member may have a longitudinal axis having a length that is different than the length of the minor axis of the second elongate scattering member.

[0020] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description, serve to explain the inventive concept. The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification.

[0022] Figure 1is a cross-sectional view of an exemplary embodiment of a liquid crystal display device including an optical film constructed according to the principles of the present invention.

[0023] Figure 2 yes Figure 1 A perspective view of an exemplary embodiment of an optical film.

[0024] Figure 3 It is along Figure 2 A cross-sectional view taken along line II'.

[0025] Figure 4 yes Figure 2 Cross-sectional view of a rod-shaped scatterer.

[0026] Figure 5 yes Figure 2 Magnified view of area A.

[0027] Figures 6A to 6C is a perspective view of an exemplary embodiment of a rod-shaped scatterer constructed in accordance with the principles of the present invention.

[0028] Figure 7 It is conceptually shown Figure 1 A diagram showing the light transmission axis and the path of the outgoing light in the display device.

[0029] Figure 8 It shows Figure 2 Plot of the refractive index of a rod-shaped scatterer and the surrounding material.

[0030] Figure 9 Is shown through Figure 2 Diagram showing the changes in light paths due to the patterned layer and rod-shaped scatterers.

[0031] Figure 10 is a diagram showing how an optical film that does not include rod-shaped scatterers generates a diffraction pattern.

[0032] Figure 11 is a diagram showing brightness characteristics according to viewing angles.

[0033] Figure 12 、 Figure 13 、 Figure 14 and Figure 15 are cross-sectional views of other exemplary embodiments of optical films constructed according to the principles of the present invention.

[0034] Figure 16 yes Figure 15 Plan view of the scattering layer.

[0035] Figure 17 、 Figure 18 、 Figure 19 、 Figure 20 and Figure 21are cross-sectional views of yet other exemplary embodiments of optical films constructed according to the principles of the present invention.

[0036] Figure 22 is a perspective view of another exemplary embodiment of an optical film constructed according to the principles of the present invention. DETAILED DESCRIPTION

[0037] In the following description, for the purpose of illustration, many specific details are set forth to provide a thorough understanding of various exemplary embodiments or implementations of the present invention. As used herein, "embodiment" and "implementation" are interchangeable terms that are non-limiting examples of one or more devices or methods employing the inventive concepts disclosed herein. However, it is apparent that various exemplary embodiments may be put into practice without these specific details or with one or more equivalent arrangements. In other examples, in order to avoid unnecessarily obscuring various exemplary embodiments, known structures and devices are shown in block diagram form. In addition, various exemplary embodiments may be different, but not necessarily exclusive. For example, without departing from the inventive concept, the specific shape, configuration, and characteristics of an exemplary embodiment may be used or implemented in another exemplary embodiment.

[0038] Unless otherwise indicated, the exemplary embodiments shown should be understood as providing exemplary features of different details of some ways in which the present invention can be implemented in practice. Therefore, unless otherwise indicated, the features, components, modules, layers, films, panels, regions and / or aspects of the various embodiments (hereinafter referred to individually or collectively as "elements") may be combined, separated, interchanged and / or rearranged without departing from the present invention.

[0039] The use of cross hatching and / or shading in the drawings is generally used to make the boundaries between adjacent elements clear. Therefore, unless specified, the presence or absence of cross hatching or shading does not represent or indicate any preference or requirement for specific materials, material properties, dimensions, proportions, commonalities between illustrated elements and / or any other characteristics, attributes, properties, etc. of the elements. In addition, in the drawings, the sizes and relative sizes of the elements may be exaggerated for the purpose of clarity and / or description. When the exemplary embodiments can be implemented differently, the specific processing order can be performed differently from the described order. For example, two processes described in succession can be performed approximately simultaneously or in an order opposite to the described order. In addition, the same reference numerals represent the same elements.

[0040] When a layer or element is referred to as being "on" another element or layer, "connected to" or "coupled to" another element or layer, it may be directly on, directly connected to or directly coupled to another element or layer, or there may be an intervening element or layer. However, when an element or layer is referred to as being "directly on" another element or layer, "directly connected to" or "directly coupled to" another element or layer, there is no intervening element or layer. For this reason, the term "connected" may represent a physical connection, an electrical connection and / or a fluid connection with or without an intervening element. In addition, the D1 axis, the D2 axis and the D3 axis are not limited to the three axes of a rectangular coordinate system (such as, x-axis, y-axis and z-axis) and may be interpreted in a broader sense. For example, the D1 axis, the D2 axis and the D3 axis may be perpendicular to each other, or may represent different directions that are not perpendicular to each other. For the purposes of this disclosure, "at least one of X, Y, and Z" and "at least one item selected from the group consisting of X, Y, and Z" may be interpreted as only X, only Y, only Z, or any combination of two or more of X, Y, and Z, such as, for example, XYZ, XYY, YZ, and ZZ. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0041] Although the terms "first," "second," etc., may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another. Thus, the first element discussed below may be referred to as the second element without departing from the teachings of the present disclosure.

[0042] Spatially relative terms such as "beneath," "below," "under," "lower," "above," "upper," "over," "higher," "side" (e.g., as in "sidewall"), and the like may be used herein for descriptive purposes, and thereby to describe the relationship of one element to another element(s) as shown in the accompanying drawings. Spatially relative terms are intended to encompass different orientations of the device in use, operation, and / or manufacture in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings were turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both orientations of above and below. Furthermore, the device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and thus the spatially relative descriptors used herein should be interpreted accordingly.

[0043] The terms used herein are for the purpose of describing specific embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, as used herein, the singular forms "a", "an" and "the" are intended to also include the plural forms. In addition, when used in this specification, the terms "comprising", "including", "including" and / or "comprising" represent the existence of stated features, integral bodies, steps, operations, elements, parts and / or their sets, but do not exclude the existence or addition of one or more other features, integral bodies, steps, operations, elements, parts and / or their sets. It should also be noted that, as used herein, the terms "roughly", "about" and other similar terms are used as approximate terms and not as terms of degree, and are therefore used to allow for the inherent deviations in measurements, calculated values ​​and / or provided values ​​that will be recognized by those of ordinary skill in the art.

[0044] Various exemplary embodiments are described herein with reference to cross-sectional and / or exploded views, which are schematic representations of idealized exemplary embodiments and / or intermediate structures. Thus, deviations from the illustrated shapes due to, for example, manufacturing techniques and / or tolerances are to be expected. Thus, the exemplary embodiments disclosed herein should not necessarily be construed as limited to the specific illustrated shapes of regions, but are intended to include deviations in shape due to, for example, manufacturing. In this manner, the regions illustrated in the accompanying drawings may be schematic in nature, and the shapes of these regions may not reflect the actual shapes of regions of a device and, therefore, are not necessarily intended to be limiting.

[0045] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present disclosure belongs. Unless expressly defined as such herein, terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense.

[0046] Figure 1 is a cross-sectional view of an exemplary embodiment of a liquid crystal display device including an optical film constructed according to the principles of the present invention. Figure 2 yes Figure 1 A perspective view of an exemplary embodiment of an optical film. Figure 3 It is along Figure 2 A cross-sectional view taken along line II'.

[0047] Reference Figures 1 to 3 The liquid crystal display device 1 may include a display panel 100 , a polarizing plate Pol disposed on / under the display panel 100 , an optical film 200 disposed on the display panel 100 , and a backlight unit 300 disposed under the display panel 100 .

[0048] The display panel 100 may include a first substrate such as an array substrate 110, a second substrate such as a color filter substrate 120, and a liquid crystal layer 130 formed in a uniform cell gap between the array substrate 110 and the color filter substrate 120. The array substrate 110 and the color filter substrate 120 face each other and are attached together, thereby maintaining the cell gap.

[0049] Common electrodes and pixel electrodes are formed in the display panel 100. In this display panel 100, an array substrate 110 and a color filter substrate 120 are attached together to apply an electric field to the liquid crystal layer 130. By adjusting the voltage of the data signal applied to the pixel electrode when applying a voltage to the common electrode, the liquid crystal molecules in the liquid crystal layer 130 rotate due to dielectric anisotropy according to the electric field between the common electrode and the pixel electrode. In this way, light is transmitted or blocked in the pixel, respectively, thereby displaying characters or images.

[0050] In order to adjust the voltage of a data signal applied to a pixel electrode in each of the pixels, a switching element such as a thin film transistor TFT is provided in each of the pixels.

[0051] Polarizing plates Pol are attached above and below the display panel 100. A lower polarizing plate Pol2 disposed between the backlight unit 300 and the display panel 100 polarizes light having passed through the backlight unit 300, and an upper polarizing plate Pol1 disposed between the display panel 100 and the optical film 200 polarizes light having passed through the display panel 100.

[0052] When natural light having vibration planes in 360-degree omnidirectional directions is incident on the lower polarizing plate Pol2 (which is a typical polarizing plate), the lower polarizing plate Pol2 transmits only light having a specific vibration plane while absorbing other light, thereby obtaining polarized light. Figure 7 An example is shown in which the lower polarizing plate Pol2 has a light transmission axis in the left-right direction. In this example, the upper polarizing plate Pol1 may have a light transmission axis in the up-down direction.

[0053] Typically, a polarizing plate (Pol) uses a polarizer with light-absorbing properties to separate light into a polarization component parallel to the incident surface and a polarization component perpendicular to the incident surface, thereby obtaining linearly polarized light. To achieve this, suitable materials are selected and processed into a film suitable for the application, achieving uniform polarization and high polarization efficiency.

[0054] For example, a polyvinyl alcohol (PVA) film treated with iodine can be used as a polarizer. In addition, a triacetyl cellulose (TAC) film or an acrylic film (for example, a polymethyl methacrylate (PMMA) film having excellent transparency, ultraviolet absorption properties and durability, as well as dimensional stability and deformation resistance) can be used as an inner substrate for protecting the PVA film as a protective layer. However, it should be understood that the present disclosure is not limited thereto.

[0055] Return to reference Figures 1 to 3 The backlight unit 300 for providing light to the display panel 100 may include at least one of a side illumination type backlight unit and a direct illumination type backlight unit according to the position of the light source 340 .

[0056] For the edge-lit backlight unit, the light source 340 is provided on one side of the display panel 100 to provide light. Specifically, in the edge-lit backlight unit 300, a plurality of light sources 340 are provided on one side of the light guide plate 310, and the reflector 330 is provided on the rear surface of the light guide plate 310.

[0057] Light emitted from light source 340 is incident on the side surface of light guide plate 310, which is made of a transparent material. Reflector 330, disposed on the rear surface of light guide plate 310, can reflect the light transmitted to the rear surface of light guide plate 310 toward optical sheet 320 on the upper surface of light guide plate 310. In this manner, light loss can be reduced and uniformity can be improved. For example, optical sheet 320 may include a diffusion sheet, a prism sheet, and a protective sheet.

[0058] Hereinafter, the optical film 200 for improving a side viewing angle will be described in detail.

[0059] The optical film 200 can be disposed on the upper polarizing plate Pol1. The optical film 200 can include a pattern layer 210 having valleys V and peaks P, a cover layer 220 having a complementary shape to and coupled to the pattern layer 210, an elongated scattering member, and a base layer 240. The elongated scattering member can take the form of quantum dots, rod-shaped scatterers, or any other element capable of diffracting light according to the principles discussed herein. For convenience, the illustrated embodiment depicts an elongated scattering member in the form of a rod-shaped scatterer 230 disposed in the valleys V of the pattern layer 210.

[0060] The pattern layer 210 may be formed on the base layer 240. The pattern layer 210 may diffuse light reaching an interface between the pattern layer 210 and the cover layer 220 to increase a diffusion effect of the light.

[0061] The pattern layer 210 may have a refractive index higher than that of the cover layer 220. For example, the difference between the refractive index of the pattern layer 210 and the refractive index of the cover layer 220 may be 0.20 or less, specifically, 0.10 to 0.20. Within the above range, the effect of improving light diffusion and visibility can be enhanced, and the effect of diffusing polarized light can be enhanced. The pattern layer 210 may have a refractive index of 1.50 or greater, specifically, 1.50 to 1.70. Preferably, the refractive index of the pattern layer 210 may be 1.61. Within the above range, the effect of diffusing light can be enhanced. The pattern layer 210 may be formed of a UV-curable composition comprising at least one of a (meth) acrylic resin, a polycarbonate resin, a silicone resin, and an epoxy resin, but is not limited thereto.

[0062] like Figure 2 As shown in , the shape of the cross section formed by the valley V and the peak P of the pattern layer 210 may be an inverted trapezoidal shape. However, the shape of the cross section formed by the valley V and the peak P is not limited thereto, and may include curved surfaces (including spherical surfaces, parabolic surfaces, elliptical surfaces, hyperbolic shapes, and amorphous shapes) as well as prismatic pattern shapes (including triangles to decagons). The shape of the cross section formed by the valley V and the peak P acts as a lens to diffuse light incident on the interface between the pattern layer 210 and the cover layer 220 in different directions according to the different positions to which the light reaches. Although Figure 2 The optical film 200 is shown to have a smooth cross-section formed of valleys V and peaks P, but the cross-section may include concave and convex portions to further enhance the diffusion effect.

[0063] The aspect ratio of the valleys V can be 1.0 or less, specifically, 0.7 to 1.0. The aspect ratio refers to the ratio of the maximum height to the maximum width of the optical structure (maximum height / maximum width). Within the above range, the contrast and the viewing angle on the side can be improved. The maximum width W1 (hereinafter referred to as maximum width W1) of the substantially flat surface of each valley V can be 15 μm or less, specifically, 5 μm to 10 μm. The maximum height H of each valley V can be 15 μm or less, specifically, 5 μm to 10 μm. Within the above ranges of width and height, a diffusion effect can be achieved. The sum of the maximum widths of the valleys V can be 40% to 60% of the overall width of the pattern layer 210, specifically, 45% to 55% of the overall width of the pattern layer 210. Within the above range, the contrast and brightness uniformity on the side can be improved, and the viewing angle on the side can be improved. By arranging the valleys V to form a repeating unit, the light diffusion effect can be enhanced. Specifically, the length of each repeating unit of the valley portion V may be less than 20 μm, specifically, 10 μm to 20 μm. Within the above range, the effect of converging and diffusing light may be enhanced. Figure 2 An optical film in which the valleys V have the same aspect ratio, maximum width, and maximum height is shown, but patterns having different aspect ratios, maximum widths, or maximum heights may be formed in the optical film.

[0064] Each of the peaks P can be formed between every two valleys in the valleys V. The light reaching the peaks P can be completely reflected and emitted from the valleys V, so that the light can be diffused. The width W2 (hereinafter referred to as the width W2) of the substantially flat surface of each of the peaks P can be equal to or greater than the maximum width W1 of each of the valleys V (W2 ≥ W1). The ratio W1 / W2 of the maximum width W1 to the width W2 can be 1.0 or less, specifically, can be 0.5 to 1.0. The width W2 of each of the peaks P can be 10 μm or less, specifically, can be 5 μm to 10 μm. Within the range of the above ratios and widths, the effect of diffusing light can be achieved. Although Figure 2 The optical film is shown to have peaks P of the same width W2, but an optical film having peaks of different widths may also be employed.

[0065] The rod-shaped scatterers 230 can be easily and randomly stacked in the valley V of the pattern layer 210. For ease of explanation, the rod-shaped scatterers 230 can be as follows: Figure 2 Arranged as a single layer in the valley V as shown in FIG, or as Figure 3 The rod-shaped scatterers 230 can diffract the light incident through the pattern layer 210 and / or the cover layer 220, thereby allowing the diffracted light to be emitted.

[0066] The rod-shaped scatterer 230 may be formed of one or more of polyimide (PI) resin, polyetherimide (PEI) resin, polyethylene terephthalate (PET) resin, polycarbonate (PC) resin, polymethyl methacrylate (PMMA) resin, polystyrene (PS) resin, styrene-acrylonitrile copolymer (SAN) resin, and silicon-acrylic resin.

[0067] The refractive index of the rod-shaped scatterer 230 may be different from the refractive index of the pattern layer 210 and the refractive index of the cover layer 220. For example, the refractive index of the rod-shaped scatterer 230 may be less than the refractive index of the pattern layer 210 and may be greater than the refractive index of the cover layer 220. In this case, the refractive index of the rod-shaped scatterer 230 may be 1.0 to 1.6. Preferably, the refractive index of the rod-shaped scatterer 230 may be 1.49. However, it should be understood that the refractive index of the rod-shaped scatterer 230 is not limited thereto. For example, the refractive index of the rod-shaped scatterer 230 may be greater than the refractive index of the pattern layer 210 and the refractive index of the cover layer 220. In this case, the refractive index of the pattern layer 210 may be 1.3 to 1.6, and the difference in refractive index between the pattern layer 210 and the cover layer 220 may be 0.20 or less, specifically, 0.10 to 0.20. The refractive index of the rod-shaped scatterer 230 may be 1.5 to 1.7. This will be referred to later. Figure 7 A change in the viewing angle of the liquid crystal display device 1 when the refractive index of the rod-shaped scatterers 230 is different from the refractive indexes of the pattern layer 210 and the cover layer 220 will be described in detail.

[0068] Figure 4 yes Figure 2 Cross-sectional view of a rod-shaped scatterer. Figure 5 yes Figure 2 Magnified view of area A. Figures 6A to 6C is a perspective view of an exemplary embodiment of a rod-shaped scatterer constructed in accordance with the principles of the present invention.

[0069] Reference Figures 3 to 5 Each of the rod-shaped scatterers 230 may have a length H1 along its longitudinal axis L and a length H2 along its short axis S, wherein the length H2 of its short axis S is different from the length H1 of the longitudinal axis L. Thus, each of the rod-shaped scatterers 230 is elongated and has directivity.

[0070] like Figure 4As shown in , the rod-shaped scatterer 230 may have a needle shape. Specifically, the cross-section of the rod-shaped scatterer 230 may be elliptical, having a first radius r1 from the center C at both endpoints E1 and E2, and a second radius r2 from the center C at another point E3, wherein the second radius r2 is smaller than the first radius r1. The second radius r2 may be the shortest radius of the cross-section of the rod-shaped scatterer 230. The radius of the cross-section of the rod-shaped scatterer 230 may decrease from both endpoints E1 and E2 to point E3. The rate of decrease in radius may decrease from both endpoints E1 and E2 to point E3.

[0071] However, it should be understood that the shape of the rod-shaped scatterer 230 is not limited thereto. Figure 6A , the rod-shaped scatterer 231 may have a cylindrical shape having a circular cross section. Figure 6B , the rod-shaped scatterer 232 may have a quadrangular prism shape having a rectangular cross section. Figure 6C , the rod-shaped scatterer 233 may have an octagonal column space, which has an octagonal cross-section.

[0072] Return to reference Figures 3 to 5 The length H1 of the longitudinal axis L of the rod-shaped scatterer 230 can be greater than the length H2 of the minor axis S. The length H1 of the longitudinal axis L of the rod-shaped scatterer 230 can be greater than the maximum width W1 of each valley V of the pattern layer 210. The length H2 of the minor axis S of the rod-shaped scatterer 230 can be less than the maximum width W1 of each valley V of the pattern 210. The length H1 of the longitudinal axis L of the rod-shaped scatterer 230 can be less than the length H from the upper surface of the valley V to the upper surface of the peak P. The length H1 of the longitudinal axis L of the rod-shaped scatterer 230 can be less than the spacing PC between the peaks P. Therefore, the rod-shaped scatterers 230 stacked in the valley V can be easily aligned along the direction in which the valley V of the pattern layer 210 extends.

[0073] The rod-shaped scatterer 230 can be arranged to be substantially parallel to the longitudinal extension direction of the valley V. It should be noted that the longitudinal axis L of the rod-shaped scatterer 230 can be arranged to be inclined relative to the longitudinal extension direction of the valley V. The angle θ formed by the longitudinal axis L of the rod-shaped scatterer 230 and the longitudinal extension direction of the valley V can be 0° to 45°. Within the above range, the rod-shaped scatterer 230 refracts the incident light that has passed through the pattern layer 210 and / or the covering layer 220 to the left / right relative to the longitudinal axis L, thereby making it possible to diffuse the light more effectively. Therefore, it is possible to reduce the brightness loss of the liquid crystal display device 1 due to light being emitted in an undesirable direction, and it is possible to increase the left and right viewing angles relative to the longitudinal axis L of the rod-shaped scatterer 230, thereby improving visibility on the desired side of the display.

[0074] Refer again Figure 2, the cover layer 220 may be in direct contact with the pattern layer 210 and may be complementarily formed and coupled to the pattern layer 210. As used herein, the phrase "the pattern layer 210 is in direct contact with the cover layer 220" means that there is no adhesive layer interposed between the pattern layer 210 and the cover layer 220 and / or an adhesive layer interposed therebetween.

[0075] After the rod-shaped diffusers 230 are stacked in the valleys V of the pattern layer 210, a cover layer 220 may be formed to cover the pattern layer 210 and the rod-shaped diffusers 230. The cover layer 220 includes a surface facing the pattern layer 210, and at least a portion of the valleys V may be filled with the cover layer 220. The phrase "at least a portion of the valleys V may be filled with the cover layer 220" includes whether the valleys V are completely or partially filled with the cover layer 220. When the valleys V are partially filled with the filling pattern, the remaining unfilled portion may be filled with air.

[0076] The cover layer 220 may have a refractive index less than 1.50, specifically, equal to or greater than 1.35 and less than 1.50. Within the above range, light can be effectively diffused, the device can be easily manufactured, and visibility can be improved. The cover layer 220 may be formed of a UV-curable transparent resin having a refractive index lower than that of the resin of the pattern layer 210. Specifically, the resin may include at least one of a (meth) acrylic resin, a polycarbonate resin, a silicone resin, and an epoxy resin, but is not limited thereto.

[0077] The base layer 240 may support the pattern layer 210. The base layer 240 is a light-transmitting layer and may transmit light emitted from the backlight unit 300 to the pattern layer 210 and the cover layer 220.

[0078] The base layer 240 and the pattern layer 210 may directly contact each other, and the base layer 240 and the pattern layer 210 may be integrally formed.

[0079] The base layer 240 may include one or more of the following items: polyesters (including polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, etc.), cellulose esters (including acrylic acid, cycloolefin polymer (COP), triacetyl cellulose (TAC), etc.) and polyvinyl acetate, polyvinyl chloride (PVC), polynorbornene, polycarbonate (PC), polyamide, polyacetal, polyphenylene ether, polyphenylene sulfide, polysulfone, polyethersulfone, polyarylate and polyimide.

[0080] Figure 7 It is conceptually shown Figure 1 A diagram showing the light transmission axis and the path of the outgoing light in the display device.

[0081] Reference Figure 1 、 Figure 2and Figure 7 An upper polarizing plate Pol1 is disposed on the upper surface of the display panel 100, and a lower polarizing plate Pol2 is disposed on the lower surface of the display panel 100. The lower polarizing plate Pol2 polarizes light emitted from the backlight unit 300, and the upper polarizing plate Pol1 polarizes light transmitted through the display panel 100. An optical film 200 for improving a viewing angle may be disposed on the upper polarizing plate Pol1.

[0082] In the following description, the up and down directions are defined as Figure 2 , and the left-right direction is defined as a direction perpendicular to the short side of the optical film 200. In other words, the up-down direction represents the longitudinal extension direction of the valley portion V and the peak portion P, and the left-right direction represents a direction perpendicular to the longitudinal extension direction of the valley portion V and the peak portion P.

[0083] The lower polarizing plate Pol2 may have a light transmission axis in the left-right direction. When natural light having a 360-degree omnidirectional vibration plane is incident on the lower polarizing plate Pol2, the lower polarizing plate Pol2 transmits only the light having the specific vibration plane while absorbing other light, thereby allowing the polarized light to be emitted toward the display panel 100.

[0084] The upper polarizing plate Pol1 may have a light transmission axis in the up-down direction. After light has passed through the liquid crystal layer 130 of the display panel 100, light having a vibration plane parallel to the light transmission axis of the upper polarizing plate Pol1 may be absorbed, while light having a vibration plane perpendicular to the light transmission axis of the upper polarizing plate Pol1 may be transmitted.

[0085] As described above, the optical film 200 may include a pattern layer 210 in which valleys V and peaks P are repeatedly formed, and a cover layer 220 having a shape complementary to and coupled to the pattern layer 210. Rod-shaped diffusers 230 may be randomly stacked in the valleys V. The longitudinal axis L of the rod-shaped diffusers 230 may be substantially parallel to the light transmission axis of the upper polarizing plate Pol1. That is, the longitudinal extension direction of the valleys V and peaks P of the pattern layer 210 may also be substantially parallel to the light transmission axis of the upper polarizing plate Pol1.

[0086] Figure 8 It shows Figure 2 Plot of the refractive index of a rod-shaped scatterer and the surrounding material.

[0087] Reference Figure 2 、 Figure 5 and Figure 8 , the optical film 200 may include a pattern layer 210, a cover layer 220, and rod-shaped diffusers 230. The pattern layer 210 and the cover layer 220 may be defined as surrounding materials of the rod-shaped diffusers 230.

[0088] The optical film 200 is characterized in that rod-shaped scatterers 230 having a refractive index of n2 are arranged in a specific direction within a surrounding material having a refractive index of n1. In this example, n2 represents the average refractive index of the rod-shaped scatterers 230 and can be expressed as (n3+n4) / 2, where the refractive index in the longitudinal axis L direction is n3 and the refractive index in the short axis S direction is n4.

[0089] As described above, in addition to the rod-like shape, the rod-shaped scatterers 230 may also have other shapes (such as cylindrical shapes) as long as they can have elongated directivity (for example, irregular spherical or square shapes). The refractive index n3 of the rod-shaped scatterers 230 may be different from n1, and the refractive index n4 may be the same as or different from n1 to suppress the vertical viewing angle and improve the horizontal viewing angle. That is, it should be noted that the refractive index n3 is set to be different from n1.

[0090] In order to suppress the vertical viewing angle and improve the horizontal viewing angle, the average refractive index n2 of the rod-shaped scatterer 230 is different from n1. The greater the difference, the more significant the effect of suppressing the vertical viewing angle.

[0091] As described above, by aligning the longitudinal axis (L) of the rod-shaped scatterer 230 having a refractive index of n2 in the surrounding material having a refractive index of n1 so as to be parallel to the light transmission axis of the upper polarizing plate Pol1, light that has passed through the upper polarizing plate Pol1 can be diffused due to the difference in refractive index between the rod-shaped scatterer 230 and the surrounding material. Since the rod-shaped scatterer 230 has a rod shape, the light that has passed through the upper polarizing plate Pol1 can be diffused more in the left-right direction and less in the up-down direction relative to the orientation. As a result, the visibility of the liquid crystal display device 1 from the desired side can be improved, and unnecessary brightness loss in the up-down direction can be reduced.

[0092] In the following, reference will be made to Figures 9 to 11 to describe the effect achieved by rod-shaped scatterers.

[0093] Figure 9 Is shown through Figure 2 Diagram of the changes in the light path due to the patterned layer and rod-shaped scatterers. Figure 10 is a diagram showing how an optical film that does not include rod-shaped scatterers generates a diffraction pattern.

[0094] Reference Figure 9 , the light Lin incident on the pattern layer 210 may pass through the upper surface of the valley V of the pattern layer 210. As described above, the rod-shaped scatterers 230 may be randomly stacked in the valley V. For example, the rod-shaped scatterers 230 may be stacked in the valley V in a plurality of layers.

[0095] Light Lin incident on the pattern layer 210 may pass through the rod-shaped scatterers 230. Compared to an optical film without rod-shaped scatterers, light L3 that has passed through the rod-shaped scatterers 230 may experience more enhancement (constructive interference) and cancellation (destructive interference) as it travels through the rod-shaped scatterers 230. Therefore, it can be expected that the possibility of generating a diffraction pattern is reduced.

[0096] Reference Figure 10 , the diffraction pattern phenomenon that may occur when the optical film 200 does not include the rod-shaped scatterer 230 will be described in more detail. External light LO incident from the outside of the liquid crystal display device 1 can be reflected by components of the liquid crystal display device 1 such as the upper polarizing plate Pol1 and the display panel 100, and can be emitted toward the optical film 200. The optical film 200 may include a pattern layer 210 in which valleys V and peaks P are formed as a regular pattern. Light passing through the regular pattern can form a diffraction pattern (rainbow artifact) through the diffraction phenomenon. Specifically, when light passes through the regular pattern, the light can be bent according to different wavelengths. If the same wavelength causes enhancement (constructive interference), the color corresponding to the wavelength may be seen. If the wavelength causes cancellation (destructive interference), the color corresponding to the wavelength may not be seen.

[0097] Return to reference Figure 9 , light Lin incident on the pattern layer 210 can pass through the interface between the pattern layer 210 and the cover layer 220. Due to the difference in refractive index between the pattern layer 210 and the cover layer 220, the light Lin incident on the interface between the pattern layer 210 and the cover layer 220 can be refracted in one direction. When there is no rod-shaped scatterer 230, the light L1 that has passed through the interface between the pattern layer 210 and the cover layer 220 travels along the path indicated by the dotted arrow. When there is a rod-shaped scatterer 230, the light L2 that has passed through the interface between the pattern layer 210 and the cover layer 220 travels along the path indicated by the solid arrow. Although the light L1 is also refracted in the left and right directions due to the valley V and the peak P, it can be seen that the light L2 is significantly refracted in the left and right directions due to the rod-shaped scatterer 230 and the valley V and the peak P. Therefore, it can be expected that the side viewing angle of the liquid crystal display device 1 will be improved.

[0098] Figure 11 is a diagram showing the brightness characteristics according to the viewing angle. Figure 11In the diagram shown in , the horizontal axis represents the field of view angle. With respect to the horizontal direction, the front of the liquid crystal display device can be defined as 0°, the left side can be defined as the negative direction, the right side can be defined as the positive direction, the left endpoint can be defined as -90°, and the right endpoint can be defined as +90°. The vertical axis represents the relative brightness obtained by normalizing the measured brightness when measuring the brightness from -90° to +90°. The angle at the point where the measured brightness is half the brightness at the front can be defined as the emission angle.

[0099] A dotted line G1 represents the brightness characteristics according to the viewing angle of the optical film 200 without the rod-shaped diffusers 230 , and a solid line G2 represents the brightness characteristics according to the viewing angle of the optical film 200 with the rod-shaped diffusers 230 .

[0100] The exit angle of the first curve G1 may be in the range of about -38° to +38°, and the exit angle of the second curve G2 may be in the range of about -58° to +58°. That is, when the optical film 200 includes the rod-shaped diffuser 230 according to the above exemplary embodiment, the exit angle may be improved by about 20°.

[0101] Hereinafter, other exemplary embodiments of the optical film will be described. In the following description, the same or similar elements will be denoted by the same or similar reference numerals, and redundant descriptions will be omitted or briefly described.

[0102] Figure 12 、 Figure 13 、 Figure 14 and Figure 15 are cross-sectional views of other exemplary embodiments of optical films constructed according to the principles of the present invention. Figure 16 yes Figure 15 Plan view of the scattering layer.

[0103] Reference Figure 3 and Figure 12 , the optical film 200_1 and Figure 3 The optical film 200 shown in FIG. 1 is different in that the pattern layer 210 is directly formed on the upper polarizing plate Pol1 .

[0104] More specifically, Figure 12 The optical film 200_1 shown in FIG may include an upper polarizing plate Pol1 , a pattern layer 210 , a cover layer 220 , and rod-shaped diffusers 230 .

[0105] In the optical film 200_1 , the pattern layer 210 may be directly formed on the upper polarizing plate Pol1 , thereby reducing the thickness of the optical film 200_1 and thus being advantageous for reducing the thickness of the liquid crystal display device 1 .

[0106] Reference Figure 3 and Figure 13, except that the optical film 201 includes the second rod-shaped scatterer 230_12 in addition to the first rod-shaped scatterer 230_11, the optical film 201 and Figure 3 The optical film 200 shown in FIG. 2 is substantially the same, wherein the first rod-shaped scatterers 230_11 are stacked in the valley portion V, and the second rod-shaped scatterers 230_12 are located in a range from the upper surface of the peak portion P to the upper surface of the cover layer 220_1.

[0107] More specifically, Figure 13 The optical film 201 shown in FIG may include a base layer 240_1 , a pattern layer 210_1 , a cover layer 220_1 , a first rod-shaped scatterer 230_11 , and a second rod-shaped scatterer 230_12 .

[0108] The first and second rod-shaped scatterers 230_11, 230_12 can be mixed with the uncured cover layer 220_1. The cover layer 220_1 mixed with the first and second rod-shaped scatterers 230_11, 230_12 can be applied as a cover pattern layer 210_1. Subsequently, by applying an electric field to both ends of the valley portion V and the peak portion P in the longitudinal extension direction, the first and second rod-shaped scatterers 230_11, 230_12 can be aligned parallel to the longitudinal extension direction. The first and second rod-shaped scatterers 230_11, 230_12 are located at different positions but can have substantially the same structure and constituent materials.

[0109] The cover layer 220_1 may be formed of a UV-curable transparent resin having a lower refractive index than the resin of the pattern layer 210_1. Specifically, the resin may include at least one of (meth)acrylic resin, polycarbonate resin, silicone resin, and epoxy resin, but is not limited thereto.

[0110] Since the optical film 201 further includes the second rod-shaped scatterers 230_12 from the upper surface of the peak portion P to the upper surface of the cover layer 220_1 in addition to the first rod-shaped scatterers 230_11 stacked in the valley portion V, the optical film 201 can further enhance the optical properties of the film. Figures 9 to 11 Described is the effect achieved by the rod-shaped scatterers.

[0111] Reference Figure 3 、 Figure 13 and Figure 14 , optical film 201_1 and Figure 13 The difference between the optical film 201 shown in FIG. 2 is that the pattern layer 210_1 is directly formed on the upper polarizing plate Pol1 .

[0112] More specifically, Figure 14The optical film 201_1 shown in FIG may include an upper polarizing plate Pol1 , a pattern layer 210_1 , a cover layer 220_1 , a first rod-shaped scatterer 230_11 , and a second rod-shaped scatterer 230_12 .

[0113] In the optical film 201_1 , the pattern layer 210_1 can be directly formed on the upper polarizing plate Pol1 , thereby reducing the thickness of the optical film 201_1 and thus being advantageous for reducing the thickness of the liquid crystal display device 1 .

[0114] Since the optical film 201_1 further includes the second rod-shaped scatterers 230_12 from the upper surface of the peak portion P to the upper surface of the cover layer 220_1 in addition to the first rod-shaped scatterers 230_11 stacked in the valley portion V, the optical film 201_1 can further enhance the optical properties of the film. Figures 9 to 11 Described is the effect achieved by the rod-shaped scatterers.

[0115] Reference Figure 3 、 Figure 8 、 Figure 15 and Figure 16 , optical film 202 and Figure 3 The optical film 200 shown in FIG. 2 is different in that the optical film 202 further includes a scattering layer 243 .

[0116] More specifically, Figure 15 The optical film 202 shown in FIG may include a base layer 240_1 , a pattern layer 210_1 , a cover layer 220_1 , first rod-shaped scatterers 230_11 , and a scattering layer 243 . The scattering layer 243 may include a resin layer 241 and third rod-shaped scatterers 242 .

[0117] The scattering layer 243 is characterized in that third rod-shaped scatterers 242 having a refractive index of n2 are arranged in a specific direction in the resin layer 241 having a refractive index of n1. In this example, n2 represents the average refractive index of the third rod-shaped scatterers 242 and can be expressed by (n3+n4) / 2, where the refractive index in the longitudinal axis L direction is n3 and the refractive index in the short axis S direction is n4.

[0118] In addition to the rod-like shape, the third rod-shaped scatterer 242 may have other shapes (such as a cylindrical shape) as long as they can have elongated directionality. The refractive index n3 of the third rod-shaped scatterer 242 may be different from n1, and the refractive index n4 may be equal to or different from n1 to suppress the vertical viewing angle and improve the horizontal viewing angle. That is, it should be noted that the refractive index n3 is set to be different from n1.

[0119] In order to suppress the vertical viewing angle and improve the horizontal viewing angle, the average refractive index n2 of the third rod-shaped scatterer 242 is different from n1. The greater the difference, the more significant the effect of suppressing the vertical viewing angle.

[0120] As described above, by aligning the longitudinal axis (L) direction of the third rod-shaped scatterer 242 with a refractive index of n2 in the resin layer 241 with a refractive index of n1 to be parallel to the light transmission axis of the upper polarizing plate Pol1, due to the difference in refractive index between the third rod-shaped scatterer 242 and the resin layer 241, the light that has passed through the covering layer 220_1 can be diffused to the left and right.

[0121] The third rod-shaped scatterers 242 can be mixed with the uncured resin layer 241. The resin layer 241 mixed with the third rod-shaped scatterers 242 can be applied to cover the cover layer 220_1. Subsequently, by applying an electric field to both ends of the valley portion V and the peak portion P in the longitudinal direction, the third rod-shaped scatterers 242 can be aligned parallel to the longitudinal direction. The first rod-shaped scatterers 230_11 and the third rod-shaped scatterers 242 are located at different locations, but can have the same structure and composition materials.

[0122] The resin layer 241 may be formed of a UV-curable transparent resin having a lower refractive index than the resin of the pattern layer 210_1. Specifically, the resin may include at least one of (meth)acrylic resin, polycarbonate resin, silicone resin, and epoxy resin, but is not limited thereto.

[0123] Figure 17 、 Figure 18 、 Figure 19 、 Figure 20 and Figure 21 are cross-sectional views of yet other exemplary embodiments of optical films constructed according to the principles of the present invention.

[0124] Reference Figure 3 、 Figure 15 and Figure 17 , except that the optical film 202_1 includes the second rod-shaped scatterers 230_22 in addition to the first rod-shaped scatterers 230_21 stacked in the valley portion V, the optical film 202_1 and Figure 15 The optical film 202 shown in FIG. 2 is substantially the same, wherein the second rod-shaped scatterers 230_22 are located within a range from the upper surface of the peak portion P to the upper surface of the cover layer 220_2.

[0125] More specifically, Figure 17 The optical film 202_1 shown in FIG may include a base layer 240_2, a pattern layer 210_2, a cover layer 220_2, a first rod-shaped scatterer 230_21, a second rod-shaped scatterer 230_22, and a scattering layer 243. The scattering layer 243 may include a resin layer 241 and a third rod-shaped scatterer 242.

[0126] Reference Figure 3 、 Figure 17 and Figure 18 , optical film 202_2 and Figure 17 The difference between the optical film 202_1 shown in FIG. 2 is that the pattern layer 210_2 is directly formed on the upper polarizing plate Pol1 .

[0127] More specifically, Figure 18 The optical film 202_2 shown in FIG may include an upper polarizing plate Pol1, a pattern layer 210_2, a cover layer 220_2, a first rod-shaped scatterer 230_21, a second rod-shaped scatterer 230_22, and a scattering layer 243. The scattering layer 243 may include a resin layer 241 and a third rod-shaped scatterer 242.

[0128] Reference Figure 3 and Figure 19 , optical film 203 and Figure 3 The difference between the optical film 200 shown in FIG. 2 is that the optical film 203 further includes a second pattern layer 210_32, a second covering layer 220_32 and a third rod-shaped scatterer 230_32.

[0129] More specifically, a first pattern layer 210_31 may be formed on a base layer 240_3. Subsequently, first rod-shaped scatterers 230_31 may be stacked in the valleys V of the first pattern layer 210_31, and a first covering layer 220_31 may be applied to cover the first pattern layer 210_31 and the first rod-shaped scatterers 230_31. Subsequently, third rod-shaped scatterers 230_32 may be stacked in the valleys V of the second pattern layer 210_32, and a second covering layer 220_32 may be applied to cover the second pattern layer 210_32 and the third rod-shaped scatterers 230_32.

[0130] Reference Figure 3 、 Figure 19 and Figure 20 , optical film 203_1 and Figure 19 The difference between the optical film 203 shown in the figure is that the optical film 203_1 includes a second rod-shaped scatterer 230_33 in addition to the first rod-shaped scatterer 230_31 stacked in the valley V of the first pattern layer 210_31, and includes a fourth rod-shaped scatterer 230_34 in addition to the third rod-shaped scatterer 230_32 stacked in the valley V of the second pattern layer 210_32, wherein the second rod-shaped scatterer 230_33 is located within the range from the upper surface of the peak P of the first pattern layer 210_31 to the upper surface of the first covering layer 220_31, and the fourth rod-shaped scatterer 230_34 is located within the range from the upper surface of the peak P of the second pattern layer 210_32 to the upper surface of the second covering layer 220_32.

[0131] Reference Figure 3 、 Figure 20 and Figure 21, optical film 203_2 and Figure 20 The difference between the optical film 203_1 shown in FIG. 2 is that the first pattern layer 210_31 is directly formed on the upper polarizing plate Pol1 .

[0132] More specifically, the optical film 203_2 may include an upper polarizing plate Pol1, a first pattern layer 210_31, a first rod-shaped scatterer 230_31, a second rod-shaped scatterer 230_33, a first covering layer 220_31, a second pattern layer 210_32, a third rod-shaped scatterer 230_32, a fourth rod-shaped scatterer 230_34 and a second covering layer 220_32.

[0133] Figure 22 is a perspective view of another exemplary embodiment of an optical film constructed according to the principles of the present invention.

[0134] Reference Figure 1 、 Figure 2 、 Figure 7 and Figure 22 , optical film 204 and Figure 2 The optical film 200 shown in FIG. 2 is different in that the length H4 of the longitudinal axis of the rod-shaped scatterers 230_4 is substantially the same as the length LS of the short side of the optical film 204 .

[0135] More specifically, the optical film 204 may include a base layer 240_4 , a pattern layer 210_4 , a cover layer 220_4 , and rod-shaped diffusers 230_4 .

[0136] The optical film 204 may include a pattern layer 210_4 having valleys V and peaks P repeatedly formed therein, and a cover layer 220_4 having a complementary shape to and coupled to the pattern layer 210_4. Rod-shaped diffusers 230_4 may be uniformly stacked in the valleys V. The longitudinal axis L of the rod-shaped diffusers 230_4 may be parallel to the light transmission axis of the upper polarizing plate Pol1. In other words, the longitudinal extension direction of the valleys V and peaks P of the pattern layer 210_4 may also be parallel to the light transmission axis of the upper polarizing plate Pol1.

[0137] It should be understood that Figure 22 The optical films shown in can be applied to Figures 12 to 21 The optical film shown in .

[0138] While certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Therefore, the inventive concept is not limited to these embodiments, but rather to the broader scope of the appended claims and to various obvious modifications and equivalent arrangements as will be apparent to those skilled in the art.

Claims

1. An optical film for a display device, comprising: base layer; a pattern layer disposed on the base layer and having a repeating pattern of valleys and peaks; a plurality of first elongated scattering members disposed on an upper surface of the valley portion; as well as a cover layer having a shape complementary to and coupled with the repeating pattern of valleys and peaks, and the first elongated scattering member being disposed between the pattern layer and the cover layer, The first elongated scattering member has a longitudinal axis having a length different from a length of a short axis of the first elongated scattering member, and the longitudinal axis of the first elongated scattering member is arranged to be inclined by 0° to 45° relative to a longitudinal extension direction of the valley.

2. The optical film according to claim 1, wherein Each of the peak portions has a width equal to or greater than a width of each of the valley portions, and wherein the pattern layer has a refractive index higher than a refractive index of the cover layer.

3. The optical film according to claim 1, wherein The first elongated scattering member includes a first rod-shaped scatterer having an elliptical cross-sectional shape.

4. The optical film according to claim 1, wherein The length of the minor axis of the first elongated scattering member is less than a width of each of the valleys.

5. The optical film according to claim 1, wherein The first elongated scattering member has a refractive index in the direction of the longitudinal axis that is different from a refractive index of at least one of the pattern layer and the cover layer.

6. The optical film according to claim 1, wherein The first elongated scattering member has a refractive index smaller than that of the pattern layer.

7. The optical film according to claim 1, wherein The optical film further includes a second elongated scattering member, and wherein the second elongated scattering member is disposed in a region extending from an upper surface of the peak to an upper surface of the cover layer.

8. The optical film according to claim 7, wherein The second elongated scattering member has a longitudinal axis having a length that is different than a length of a minor axis of the second elongated scattering member.

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