Optical film, optical film-equipped polarizing plate, and display device

Abstract

This optical film is provided with: a low refractive index layer that includes a plurality of lens parts; and a high refractive index layer that is filled between the plurality of the lens parts. The lens parts, which have columnar shapes and have flat sections at the respective tips, are arranged two-dimensionally. When AIN represents a distance between the flat sections of the lens parts adjacent to each other in a first direction parallel to a film surface, AEX represents a distance between end portions on the opposite side to the flat sections of the lens parts adjacent to each other in the first direction, PA represents a pitch in the first direction of the lens parts adjacent to each other in the first direction, BIN represents a distance between the flat sections of the lens parts adjacent to each other in a second direction, BEX represents a distance between end portions on the opposite side to the flat sections of the lens parts adjacent to each other in the second direction, PB represents a pitch that is a distance between at a medium point in the second direction of the lens parts adjacent to each other in the second direction, ((PA-((AIN+AEX) / 2))*(PB-((BIN+BEX) / 2))) / (PA*PB) equals

Description

[Technical Field]

[0001] This disclosure relates to an optical thin film that causes optical effects on light emitted from the display surface of a display device. Furthermore, this disclosure relates to an optical thin film-equipped polarizing plate and a display device having the optical thin film. [Previous Technology]

[0002] One example of a display device is a liquid crystal display device, used in various fields. Furthermore, organic LED (Organic Light Emitting Diode) display devices are also becoming increasingly popular.

[0003] In liquid crystal display devices, there are cases where the color tone of the image within the viewing angle changes greatly due to changes in light intensity in response to viewing angle, light leakage in the tilt direction, etc.

[0004] On the other hand, in organic LED display devices, images viewed from an oblique angle are prone to blue shift. Blue shift refers to the phenomenon that an image viewed from an oblique angle appears bluer than an image viewed from the front. That is, even images displayed by organic LED display devices can exhibit significant changes in hue within the viewing angle due to this blue shift. Furthermore, blue shift is particularly pronounced in organic LED display devices employing a microcavity structure.

[0005] The color variation within the viewing angle described above is a factor that degrades the display quality of the image. Other factors affecting display quality include, for example, uneven contrast within the viewing angle. Various technologies for improving image display quality have been proposed in the past. For example, JPH07-43704A, JP3272833A, JP3621959A, JP2016-126350A, JP2012-145944A, JP2011-118393A and US9507059B disclose optical films provided on the display surface of a display device to improve image display quality. [Summary of the Invention]

[0006] In conventional optical films, light diffusion is achieved by reflecting and / or refracting light from a liquid crystal panel at the interface of two layers with a refractive index difference, such as the interface between two layers. Such conventional optical films generally have a long, narrow lens portion extending between the two ends of the film. In this structure, the fabrication of the optical film is easier because processes such as demolding become easier. However, while the improvement in display quality within the viewing angle is effective in the direction perpendicular to the length direction of the lens portion, it is not particularly noticeable in the length direction of the lens portion. Therefore, it may not be considered ideal for use with devices that have image rotation capabilities, such as smartphones.

[0007] On the other hand, US9507059B proposes an optical film with a two-dimensional arrangement of cylindrical multiple lens sections. In this structure, improvements in display quality in two directions, such as the left-right and up-down directions, can be expected. However, because the optical film in US9507059B has a small film section and a steep slope, light may not diffuse sufficiently over a wide angle. Furthermore, the valleys between the lens sections and the rounded front ends may cause undesirable diffusion of light parallel to the frontal viewing direction, thus potentially leading to undesirable loss in display quality, such as brightness level, when viewed from the front.

[0008] This disclosure was made in consideration of the above-mentioned facts, and its purpose is to provide an optical thin film, an optical thin film-attached polarizing plate having the same, and a display device that can maintain good display quality of the display device when viewed from the front and effectively suppress color changes within the viewing angle.

[0009] The optical thin film disclosed herein is: An optical thin film comprising: a low refractive index layer including a plurality of lens portions, and a high refractive index layer disposed such that it fills the spaces between the plurality of lens portions, and having a refractive index higher than that of the low refractive index layer; The lens portions are cylindrical in shape that tapers towards the high refractive index layer side, and have a flat portion at the front end of the high refractive index layer side that is parallel to the film surface of the optical thin film; The plurality of lens portions are arranged in two dimensions in a first direction parallel to the film surface and a second direction perpendicular to the first direction; The distance in the first direction between the flat portions of the lens portions adjacent to each other in the first direction is defined as AIN; The distance in the first direction between the ends opposite to the flat portions of the lens portions adjacent to each other in the first direction is defined as AEX; The distance in the first direction between the midpoints of the lens portions adjacent to each other in the first direction, i.e., the first direction spacing, is defined as PA; The distance in the second direction between the flat portions of the lens portions adjacent to each other in the second direction is defined as BIN. The distance in the second direction between the ends opposite to the flat portion of the lens portion adjacent to the first second direction is set as BEX; when the distance in the second direction between the midpoints of the first second direction of the lens portions adjacent to the first second direction, i.e., the second direction spacing, is set as PB, ((PA-((AIN+AEX) / 2))×(PB-((BIN+BEX) / 2))) / (PA×PB) becomes 0.42 or more and 0.70 or less.

[0010] When the height of the aforementioned lens portion is set to H, H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) may each be 1.40 or more and 3.00 or less.

[0011] Furthermore, the optical thin film disclosed herein is: an optical thin film comprising: a low refractive index layer including a plurality of lens portions, and a high refractive index layer disposed such that it fills the spaces between the plurality of lens portions, and having a refractive index higher than that of the low refractive index layer; the aforementioned lens portions are cylindrical in shape that tapers towards the high refractive index layer side, and have a flat portion at the front end of the aforementioned high refractive index layer side that is parallel to the thin film surface of the aforementioned optical thin film; the aforementioned plurality of lens portions are arranged in two dimensions in a first direction parallel to the aforementioned thin film surface and a second direction perpendicular to the aforementioned first direction; The distance in the first direction between the flat portions of the aforementioned lens portions adjacent in the first direction is set as AIN; the distance in the first direction between the ends opposite to the flat portions of the aforementioned lens portions adjacent in the first direction is set as AEX; the distance in the second direction between the flat portions of the aforementioned lens portions adjacent in the second direction is set as BIN; the distance in the second direction between the ends opposite to the flat portions of the aforementioned lens portions adjacent in the second direction is set as BEX; when the height of the aforementioned lens portion is set as H, H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) are each 1.40 or more and 3.00 or less.

[0012] Furthermore, in the optical thin film disclosed herein, the aforementioned flat portion of the aforementioned lens portion may also be arranged in a manner facing the display panel side.

[0013] The aforementioned multiple lens portions are arranged in a matrix, and the aforementioned high refractive index layer may also include a grid-shaped portion.

[0014] The aforementioned lens portion is a square pyramid shape, and the aforementioned flat portion may also be a square.

[0015] The aforementioned lens portion is a square pyramid shape, and the aforementioned flat portion may also be rectangular.

[0016] The side of the aforementioned lens portion may also be a curved surface that convexes on the side of the aforementioned high refractive index layer.

[0017] Furthermore, the optical thin film disclosed herein is: an optical thin film comprising: a low refractive index layer including a plurality of lens portions, and a high refractive index layer disposed such that it fills the space between the plurality of lens portions, and having a refractive index higher than that of the low refractive index layer; the lens portions are cylindrical in shape that tapers to one side in the normal direction of the film surface of the optical thin film, and have a flat portion parallel to the film surface at the front end of the aforementioned side; the plurality of lens portions are arranged in two dimensions in a first direction parallel to the film surface and a second direction perpendicular to the first direction; the distance in the first direction between the flat portions of the aforementioned lens portions adjacent in the first direction is defined as AIN; the distance in the first direction between the ends opposite to the flat portions of the aforementioned lens portions adjacent in the first direction is defined as AEX; the distance in the first direction between the midpoints of the aforementioned lens portions adjacent in the first direction, i.e., the first direction spacing, is defined as PA; the distance in the second direction between the flat portions of the aforementioned lens portions adjacent in the second direction is defined as BIN. The distance in the second direction between the ends opposite to the flat portion of the lens portion adjacent to the lens portion in the second direction is set as BEX; when the distance in the second direction between the midpoints of the lens portions adjacent to the lens portion in the second direction, i.e., the second direction spacing, is set as PB, then ((PA-((AIN+AEX) / 2))×(PB-((BIN+BEX) / 2))) / (PA×PB) becomes 0.42 or more and 0.70 or less. In this optical film, when the height of the lens portion is set as H, H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) can each become 1.40 or more and 3.00 or less.

[0018] Furthermore, the optical thin film disclosed herein is: an optical thin film comprising: a low refractive index layer including a plurality of lens portions, and a high refractive index layer disposed such that it fills the spaces between the plurality of lens portions, and having a refractive index higher than that of the low refractive index layer; the aforementioned lens portions are cylindrical in shape that tapers to one side in the normal direction of the thin film surface of the aforementioned optical thin film, and have a flat portion parallel to the aforementioned thin film surface at the front end of the aforementioned side; the aforementioned plurality of lens portions are arranged in two dimensions in a first direction parallel to the aforementioned thin film surface and a second direction perpendicular to the aforementioned first direction; The distance in the first direction between the flat portions of the aforementioned lens portions adjacent in the first direction is set as AIN; the distance in the first direction between the ends opposite to the flat portions of the aforementioned lens portions adjacent in the first direction is set as AEX; the distance in the second direction between the flat portions of the aforementioned lens portions adjacent in the second direction is set as BIN; the distance in the second direction between the ends opposite to the flat portions of the aforementioned lens portions adjacent in the second direction is set as BEX; when the height of the aforementioned lens portion is set as H, H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) are each 1.40 or more and 3.00 or less.

[0019] Furthermore, the display device disclosed herein includes: the aforementioned optical thin film; and an organic LED panel on which the aforementioned optical thin film is disposed on the display surface.

[0020] Furthermore, the display device disclosed herein includes: the aforementioned optical thin film; and a liquid crystal panel on which the aforementioned optical thin film is disposed on the display surface.

[0021] Furthermore, the optical thin film polarizing plate disclosed herein comprises: the aforementioned optical thin film; and a polarizing plate bonded to the aforementioned optical thin film.

[0022] According to this disclosure, it is possible to maintain good display quality of the two display devices when viewed from the front and to effectively suppress color changes within the viewing angle.

Implementation Method

[0023] Hereinafter, various embodiments of this disclosure will be described with reference to the drawings.

[0024] Furthermore, in this specification, the terms "sheet," "film," and "plate" are used only for abbreviated meaning and are not intended to distinguish one another. Therefore, for example, "sheet" can also encompass components that can be called films and plates. Also, in this specification, "sheet surface (plate surface, film surface)" refers to the surface that aligns with the planar direction (surface direction) of the sheet-like component when viewed as a whole and roughly. Furthermore, "sheet surface (plate surface, film surface)" can also be referred to as the main surface. Moreover, in this specification, the normal direction of the sheet-like component refers to the direction of normal to the sheet-like component facing the sheet surface.

[0025] <First Embodiment> Figure 1 is a schematic diagram showing the structure of a display device 10 equipped with the optical thin film 100 of the first embodiment. The display device 10 is constructed by sequentially laminating an organic LED (Organic Light Emitting Diode) panel 15, a circular polarizing plate 20, a touch panel 30, a protective glass 40, and an optical thin film 100. The display device 10 of this embodiment is exemplified as a smartphone. However, the display device 10 can also be a tablet terminal, a television, a computer monitor, a car navigation system, etc.

[0026] The display surface 15A of the organic LED panel 15 is bonded to the inside of the circular polarizer 20 with a first adhesive layer 51. The surface of the circular polarizer 20 is bonded to the inside of the touch panel 30 with a second adhesive layer 52. The surface of the touch panel 30 is bonded to the inside of the protective glass 40 with a third adhesive layer 53. Each adhesive layer 51 to 53 is a so-called OCA (Optical Clear Adhesive), which has high light transmittance.

[0027] The optical film 100 is disposed on the surface of the protective glass 40. In this example, although the optical film 100 and the protective glass 40 are not bonded together with an adhesive layer, they can also be bonded together with an adhesive layer.

[0028] In Figure 1 and the following description, the symbol D1 represents the direction parallel to the thin film surface of the optical thin film 100, i.e., the first direction. The symbol D2 represents the direction parallel to the thin film surface of the optical thin film 100 and perpendicular to the first direction D1, i.e., the second direction. Furthermore, the symbol D3 represents the third direction perpendicular to both the first direction D1 and the second direction D2.

[0029] While the organic LED panel 15 is an organic LED panel employing a microcavity structure, other forms are also possible. In general organic LED panels, blue shift is prone to occur in images viewed from an oblique angle. Such blue shift is particularly noticeable in organic LED panels employing a microcavity structure. In the display device 10, color variation within the viewing angle is suppressed by means of an optical thin film 100.

[0030] In this embodiment, a circular polarizer 20, a touch panel 30, and a protective glass 40 are disposed between the organic LED panel 15 and the optical film 100. The circular polarizer 20 includes a polarizing element and a retardation plate. The retardation plate is disposed on the side of the organic LED panel 15, and the polarizing element is attached to a surface opposite to the side of the organic LED panel 15 to the retardation plate. Specifically, the polarizing element is a linearly polarized photon, and the retardation plate is a λ / 4 retardation plate. The touch panel 30 includes a transparent glass plate. It is preferable that the touch panel 30 is capacitive. The protective glass 40 has a protective function. However, the protective glass 40 may also have other functions such as anti-reflective properties.

[0031] The optical thin film 100 includes a low-refractive-index layer 102 and a high-refractive-index layer 103 that are bonded together. Although no substrate is disposed on the side opposite to the high-refractive-index layer 103 side of the low-refractive-index layer 102, a substrate may be included.

[0032] FIG2 is a partial oblique view of the optical thin film 100. In FIG2, the high refractive index layer 103 is represented by a two-point chain line for ease of explanation. FIG3 is a view of the low refractive index layer 102 from the normal direction, in other words, a view seen in the third direction D3. FIG3 schematically shows the arrangement of the lens portions 110 provided by the low refractive index layer 102, which will be described later. Furthermore, FIG4 is a cross-sectional view when the optical thin film 100 is cut along the IV-IV line of FIG3. FIG5 is a cross-sectional view when the optical thin film 100 is cut along the VV line of FIG3.

[0033] The low-refractive-index layer 102 integrally comprises a thin-film layer body 102A having a surface and an interior, and a plurality of lens portions 110 arranged in two dimensions in a first direction D1 and a second direction D2 on the interior of the layer body 102A. In contrast, the high-refractive-index layer 103 is deposited on the low-refractive-index layer 102 in such a way that it covers the lens portions 110 and fills the spaces between the plurality of lens portions 110. Thus, in this embodiment, the interface between the low-refractive-index layer 102 and the high-refractive-index layer 103 forms an uneven shape. The high-refractive-index layer 103 is formed as a thin film having a plurality of holes for accommodating the plurality of lens portions 110, more specifically, it is a grid or lattice shape. Specifically, the high-refractive-index layer 103 comprises a thin-film layer body 103A having a surface and an interior, and a grid-shaped portion 103B. The grid-shaped portion 103B is integral on the surface of the layer body 103A facing the low-refractive-index layer 102. When viewed in the third direction D3, the grid-shaped portion 103B forms a grid shape (such as a hash shape). Furthermore, the low-refractive-index layer 102 may not have a layer body 102A, but can be formed by an assembly of multiple lens portions 110. Similarly, the high-refractive-index layer 103 may also not have a layer body 102A, but can be formed solely by the grid-shaped portion 103B.

[0034] As shown in Figure 3, the lens sections 110 are arranged in a matrix-like two-dimensional arrangement. Specifically, a column is formed by a plurality of lens sections 110 arranged at equal intervals in the first direction D1, and then arranged at equal intervals in the second direction D2. In this example, all the plurality of lens sections 110 are of the same shape. Furthermore, the lens sections 110 adjacent to each other in the second direction D2 are not misaligned in the first direction D1, but are facing each other in the second direction D2.

[0035] Furthermore, the lens portion 110 is a cylindrical shape that tapers to a lower side in FIG. 1 on one side of the normal direction of the thin film surface of the optical thin film 100. Next, the lens portion 110 has a flat portion 111 extending along the surface direction of the low refractive index layer 102 and the high refractive index layer 103 (that is, the thin film surface of the optical thin film 100) at its front end on the aforementioned normal direction side, i.e., the high refractive index layer 103 side. Specifically, the lens portion 110 is a square pyramid, more specifically a regular square pyramid, and the flat portion 111 is rectangular, more specifically a square. On the other hand, the lens portion 110 has four side surfaces 110S connected between the flat portion 111 and the layer body 102A in a rectangular shape.

[0036] As shown in Figure 4, the two side surfaces 110S of the enclosing flat portion 111 facing each other in the first direction D1 taper on the side of the high refractive index layer 103. As shown in Figure 5, the two side surfaces 110S of the enclosing flat portion 111 facing each other in the second direction D2 also taper on the side of the high refractive index layer 103. Furthermore, the four side surfaces 110S are convex curved surfaces on the side of the high refractive index layer 103.

[0037] Side surface 110S may be a convex curved surface on the side of the high refractive index layer 103 forming the arc when viewed in cross-section, or it may be a convex curved surface on the side of the high refractive index layer 103 forming the elliptical arc. Alternatively, side surface 110S may be a convex folded surface on the side of the high refractive index layer 103. Alternatively, side surface 110S may be a concave curved surface or folded surface on the side of the high refractive index layer 103, or it may be a flat surface.

[0038] Although the figures are obvious, in this embodiment, the optical thin film 100 is arranged with the high refractive index layer 103 facing the organic LED panel 15. In other words, the optical thin film 100 is arranged with the flat portion 111 of the lens portion 110 facing the organic LED panel 15. Therefore, the high refractive index layer 103 is located on the incident side of light from the organic LED panel 15, and the low refractive index layer 102 is located on the emitting side of light.

[0039] The symbols AIN, AEX, and PA shown in Figure 4 have the following meanings: • AIN: The distance in the first direction D1 between the flat portions 111 of adjacent lens portions 110, i.e., the incident width on the high refractive index side in the first direction. • AEX: The distance in the first direction D1 between the ends opposite to the flat portions 111 of adjacent lens portions 110, i.e., the exit width on the high refractive index side in the first direction. • PA: The distance in the first direction D1 between the midpoints of the flat portions 111 of adjacent lens portions 110, i.e., the spacing in the first direction.

[0040] The symbols BIN, BEX, and PB shown in Figure 5 have the following meanings: • BIN: The distance in the second direction D2 between the flat portions 111 of adjacent lens portions 110, i.e., the incident width on the high refractive index side in the second direction. • BEX: The distance in the second direction D2 between the ends opposite to the flat portions 111 of the lens portions 110 adjacent to the second direction D2, i.e., the exit width on the high refractive index side in the second direction. • PB: The distance in the second direction D2 between the midpoints of the two directions D2 of adjacent lens portions 110, i.e., the spacing in the second direction.

[0041] Furthermore, the symbol H in Figures 4 and 5 indicates the height of the lens portion 110.

[0042] The optical thin film 100 of this embodiment satisfies the following conditions (1) and (2). • Condition (1): ((PA-((AIN+AEX) / 2))×(PB-((BIN+BEX) / 2))) / (PA×PB) is 0.42 or more and 0.70 or less. • Condition (2): H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) are each 1.40 or more and 3.00 or less.

[0043] Furthermore, in the following, ((PA-((AIN+AEX) / 2))×(PB-((BIN+BEX) / 2))) / (PA×PB) in condition (1) will be called the slope ratio. Also, H / ((AIN+AEX) / 2) in condition (2) will be called the average aspect ratio of the view in the first direction, and H / ((BIN+BEX) / 2) will be called the average aspect ratio of the view in the second direction.

[0044] The inventors of this invention have discovered that when conditions (1) or (2) above are met, the display device 10 can maintain good display quality when viewed from the front and effectively suppress color changes within the viewing angle. The inventors of this invention have further discovered that when conditions (1) and (2) are met simultaneously, this effect can be further improved.

[0045] The optical thin film 100 causes total internal reflection of light L1 to L3 from the organic LED panel 15, such as that shown in FIG. 4, at the side 110S of the lens portion 110, thus diffusing the total internally reflected light to a wide angle range on the high-angle side. The smaller the lens portion 110, the less light can be totally internally reflected at the side 110S. Furthermore, if the lens portion 110 is small and the side 110S is sharply tilted, light will not diffuse to a wide range. Also, if the side 110S is sharply tilted and the front end of the lens portion 110 is pointed or rounded, light parallel to the frontal viewing direction will diffuse undesirably. The inventors of this invention considered these matters and, as a result of research on the shape / size of the lens portion 110, discovered the above conditions (1) and (2).

[0046] More specifically, the following insight is obtained: when light emitted from the organic LED panel 15 through the optical film 100 is observed from the front view direction of the display device 10 parallel to the third direction D3, and in a plane containing the front view direction and the first direction D1 at a 45-degree angle relative to the aforementioned front view direction, and the color change Δu'v' of the light emitted in the aforementioned 45-degree direction relative to the light emitted in the front view direction is calculated, it is expected that the color change Δu'v' with the optical film 100 will be less than 75% of the color change without the optical film 100. Similarly, the following insight is obtained: when observing the light emitted from the organic LED panel 15 through the optical film 100 from the front view direction of the display device 10 parallel to the third direction D3, and from the direction at a 45-degree angle relative to the aforementioned front view direction in a plane including the front view direction and the second direction D2, and calculating the color change Δu'v' of the light emitted in the aforementioned 45-degree direction relative to the light emitted in the front view direction, it is expected that the color change Δu'v' with the optical film 100 will be less than 75% of the color change without the optical film 100.

[0047] Furthermore, the color change Δu'v' represents the color difference. In this embodiment, the smaller this value, the smaller the color difference relative to the light emitted in the frontal viewing direction. The color change Δu'v' is calculated from the colors defined by u' and v' in an equal color space. The value of Δu'v' for an angle θ in a certain viewing angle is represented by Equation (1). Substituting the value of 45 degrees into θ in Equation (1), the color change at a viewing angle of 45 degrees can be obtained.

[0048]

[0049] The color coordinates of the uniform color space in equation (1), namely u' and v', are represented by equations (2-1) and (2-2) respectively.

[0050]

[0051] In the above formulas, x and y are color coordinates defined by the CIE1931 color space (CIE xyY color space).

[0052] Furthermore, the symbol θA in Figure 4 represents the angle between the endpoint of the high refractive index layer 103 on the side of side 110S and its opposite endpoint, which forms an acute angle with the third direction D3. The symbol θB in Figure 5 represents the angle between the acute angle of the straight line passing through the endpoint of the high refractive index layer 103 on the side of side 110S and its opposite endpoint, which forms an acute angle with the third direction D3. These angles θA and θB are determined within a range of 15 degrees greater than 0 degrees, provided that the conditions (1) and (2) above are satisfied. It is preferable for angles θA and θB to be 10 degrees greater than 0 degrees, and even better if they are 5 degrees or more but less than 10 degrees. If they are less than 0 degrees, it will result in an undesirable condition where it is difficult to demold from the metal mold. Furthermore, if they are 15 degrees or more, there will be a situation where the light totally reflected by side 110S travels at an excessive angle, which may result in an undesirable condition of reduced brightness on the front side. In addition, angles θA and θB correspond to the "average slope angle" shown in Table 1, etc., described later.

[0053] Furthermore, when conditions (1) and (2) above are met, it is preferable that the incident width AIN on the high refractive index side of the first direction and the exit width AEX on the high refractive index side of the first direction are formed in such a way that ((AIN-AEX)×2) / PA is 0.2 to 0.5 (20% to 50% in the case of percentage). Also, it is preferable that the incident width BIN on the high refractive index side of the second direction and the exit width BEX on the high refractive index side of the second direction are formed in such a way that ((BIN-BEX)×2) / PB is 0.2 to 0.5 (20% to 50% in the case of percentage). If ((AIN-AEX)×2) / PA or ((BIN-BEX)×2) / PB is less than 0.2, there is a concern that effective suppression of color change may not be achieved. Furthermore, if ((AIN-AEX)×2) / PA or ((BIN-BEX)×2) / PB is larger than 0.5, there is a concern that the brightness of the front side will be reduced.

[0054] In this embodiment, the low-refractive-index layer 102 and the high-refractive-index layer 103 are selected such that the difference between the refractive index of the low-refractive-index layer 102 and the refractive index of the high-refractive-index layer 103 is in the range of 0.05 to 0.60. When the optical thin film 100 is combined with the organic LED panel 15, the difference between the refractive index of the low-refractive-index layer 102 and the high-refractive-index layer 103 is preferably 0.05 to 0.50, and more preferably 0.10 to 0.20. Similarly, when the optical thin film 100 is combined with a liquid crystal panel instead of the organic LED panel 15, the difference between the refractive index of the low-refractive-index layer 102 and the high-refractive-index layer 103 is preferably 0.05 to 0.50, and more preferably 0.10 to 0.20.

[0055] Furthermore, the refractive index of the low refractive index layer 102 is, for example, 1.40 or more and 1.55 or less, and the refractive index of the high refractive index layer 103 is, for example, 1.55 or more and 1.90 or less, which is greater than the refractive index of the low refractive index layer 102.

[0056] Furthermore, as with the optical thin film 100 described above, the high refractive index layer 103 is located on the incident side of light from the organic LED panel 15, and the low refractive index layer 102 is located on the emitting side of light. In this embodiment, by satisfying the above conditions (1) and (2), it is sought to ensure that more light is totally reflected from the high refractive index layer 103 to the side 110S of the lens portion 110, i.e., the part of the lens portion 110. If the low refractive index layer 102 is located on the incident side of light from the organic LED panel 15, and the part of the lens portion 110 is formed on the high refractive index layer 103, it becomes difficult to ensure a greater amount of totally reflected light. Therefore, the optical thin film 100 has the high refractive index layer 103 disposed on the organic LED panel 15 side. However, the inventors of this invention have found that when the low refractive index layer 102 is located on the incident side of light from the organic LED panel 15 and has the lens portion 110, beneficial optical performance is obtained.

[0057] Furthermore, the low refractive index layer 102 may be formed, for example, by curing an ultraviolet-curable resin, an electron beam-curable resin, or a thermosetting resin. When the low refractive index layer 102 is formed by curing an ultraviolet-curable resin, the ultraviolet-curable resin may contain an acrylic resin or an epoxy resin.

[0058] Similarly, the high refractive index layer 103 can also be formed by curing, for example, an ultraviolet-curable resin, an electron beam-curable resin, or a thermosetting resin. When the high refractive index layer 103 is formed by curing an ultraviolet-curable resin, the ultraviolet-curable resin can be an acrylic resin or an epoxy resin. Furthermore, when the high refractive index layer 103 is formed as an adhesive layer, it can be formed using an acrylic resin adhesive.

[0059] Furthermore, the thickness of the layer body 102A in the third direction D3 of the low refractive index layer 102 is, for example, 0.5 μm or more and 30 μm or less. Also, the height of the lens portion 110 is, for example, 1.0 μm or more and 30 μm or less. On the other hand, the thickness of the high refractive index layer 103 is 5 μm or more and 100 μm or less. Furthermore, the thickness of the high refractive index layer 103 is the distance from the endpoint of the grid-shaped portion 103B on the low refractive index layer 102 side to the surface of the layer body 103A opposite to the low refractive index layer 102 side.

[0060] Next, the function of this embodiment will be explained.

[0061] After the light used to form the image is emitted from the organic LED panel 15, the light passes through the circular polarizer 20, the touch panel 30 and the protective glass 40 and is incident on the optical film 100. Among the light incident on the optical film 100, the light that is directed along the frontal viewing direction toward the flat portion of the layer body 102A between the flat portion 111 or the adjacent lens portion 110, as shown by symbols L4 and L5 in FIG4, is emitted from the low refractive index layer 102 without changing the angle of the direction of travel or with almost no change, which helps to form an image in the frontal view.

[0062] On the other hand, light incident on the optical thin film 100 that is directed toward the side 110S of the lens section 110 along the frontal viewing direction or at a direction tilted at only a small angle relative to the frontal viewing direction is totally reflected at the side 110S, as shown by the symbols L1 to L3 in FIG4, causing the direction of propagation to become a high-angle side and exiting from the low refractive index layer 102. That is, light that is tilted at only a small angle relative to the frontal viewing direction is totally reflected at the side 110S and enters a higher-angle side than before. In this way, most of the light is avoided from being concentrated in the frontal viewing direction, forming a high-quality image viewed in the tilted direction.

[0063] In this embodiment, the optical thin film 100 is formed in a manner that satisfies the above conditions (1) and (2), and because the lens portion 110 is formed into an elongated shape in the height direction, the area of ​​the side surface 110S can be increased. Furthermore, because light can be easily guided from between adjacent lens portions 110 to the side surface 110S of the lens portion 110, light can be diffused over a wide range. In addition, by providing a flat portion 111 at the front end of the lens portion 110, the unwanted diffusion of light traveling along the frontal viewing direction is avoided, and the reduction in image quality in the frontal view is suppressed. Next, because the lens portion 110 is a cylindrical shape that tapers towards the high refractive index layer 103, color changes can be suppressed in both the direction inclined relative to the frontal viewing direction in the plane including the frontal viewing direction and the first direction D1, and the direction inclined relative to the frontal viewing direction in the plane including the frontal viewing direction and the second direction D2.

[0064] As described above in this embodiment, the display device can maintain good display quality when viewed from the front and can effectively suppress color changes within the viewing angle.

[0065] Hereinafter, variations of the above-described embodiments will be described. Figures 6 to 9 show variations of the above-described embodiments. Elements in each variation that are the same as those described in the above-described embodiments are shown with the same symbols, and descriptions of differences are omitted.

[0066] In the modified example shown in Figure 6, the side surface 110S is a folded surface, having three element surfaces that are respectively composed of planes: the first element surface 131, the second element surface 132, and the third element surface 133. In the modified example shown in Figure 7, the side surface 110S includes a curved surface 134 and a folded surface with two element surfaces 135 and 136 that are respectively composed of planes. In the modified example shown in Figure 8, the side surface 110S includes a curved surface 137 and a plane 138.

[0067] The modified display device 10' shown in FIG9 is constructed by sequentially laminating an organic LED panel 15, an optical film 100, a circular polarizer 20, a touch panel 30, and a protective glass 40. The optical film 100 is disposed on the display surface (surface) 15A of the organic LED panel 15. The surface of the optical film 100 is bonded to the inside of the circular polarizer 20 with an adhesive layer 510. The surface of the circular polarizer 20 is bonded to the inside of the touch panel 30 with an adhesive layer 520. The surface of the touch panel 30 is bonded to the inside of the protective glass 40 with an adhesive layer 530. Each adhesive layer 510, 520, and 530 is a so-called OCA (Optical Clear Adhesive), which has high light transmittance. In this example, although the organic LED panel 15 and the optical film 100 are not bonded with an adhesive layer, it is also possible for the organic LED panel 15 and the optical film 100 to be bonded with an adhesive layer.

[0068] In the modified display device 10', the circular polarizer 20 is positioned further away from the optical film 100 on the side where external light is incident (on the protective glass 40 side). Therefore, when external light is incident from the protective glass 40 onto the organic LED panel 15, the circular polarizer 20 makes it difficult for the external light to enter the optical film 100, thus suppressing multiple reflections within the optical film 100. This suppresses the occurrence of discernible obstructions such as iris unevenness and interference fringes, ensuring good image discernibility.

[0069] Furthermore, although the lens portion 110 in the low refractive index layer 102 in the above embodiment is a square pyramid, it can also be a cone, a hexagonal pyramid, or an octagonal pyramid. Also, the arrangement of the lens portions 110 is not limited to a matrix shape; for example, a houndstooth pattern is also possible.

[0070] Furthermore, when viewing the lens portion 110 in the normal direction of the low-refractive-index layer 102, in the above-described embodiment, the flat portion 111 and the base portion are square. That is, as shown in FIG3, when viewing the lens portion 110 in the normal direction of the low-refractive-index layer 102, the aspect ratio (first maximum width W1: second maximum width W2 in the direction perpendicular to the first specified maximum width W) of the lens portion 110 (flat portion 111 and base portion) is 1:1. However, the shape of the lens portion 110 is not limited, and W1:W2 can be approximately 1:3 to 3:1. The direction specifying the first maximum width W1 or the direction specifying the second maximum width W2 can be parallel to the first direction D1. If the difference between the first maximum width W1 and the second maximum width W2 is greater than 3 times, the productivity reduction caused by the difficulty of demolding and the risk of collapse of the lens portion 110 increase.

[0071] Furthermore, although the above-mentioned display devices 10 and 10' have a combination of an organic LED panel 15 and a lens portion 110 arranged in a two-dimensional optical film 100, a combination of a liquid crystal panel and an optical film 100 is also possible.

[0072] Furthermore, when assembling the display device 10' shown in FIG9, it is also possible to pre-fabricate an optical thin film-attached polarizing plate that integrates the optical thin film 100 with the circular polarizing plate 20. In this case, the low refractive index layer 102 of the optical thin film 100 and the phase difference plate of the circular polarizing plate 20 are attached.

[0073] <Second Embodiment> FIG10 is a schematic diagram showing the structure of the display device 10” equipped with the optical thin film 200 of the second embodiment. Those structural parts in this embodiment that are the same as those in the first embodiment are shown with the same reference numerals, and their descriptions are omitted.

[0074] In the optical thin film 200 of the display device 10” in the second embodiment, the orientations of the low refractive index layer 102 and the high refractive index layer 103 are opposite to those of the low refractive index layer 102 and the high refractive index layer 103 in the optical thin film 100 of the first embodiment. The other structures are the same as those in the first embodiment.

[0075] That is, in the second embodiment of the display device 10”, the optical thin film 200 has a low refractive index layer 102 located on the incident side of light from the organic LED panel 15, and the low refractive index layer 102 has a lens portion 110.

[0076] Similarly, in this optical thin film 200, because the following conditions (1) and / or conditions (2) described in the first embodiment are met, good display quality of the display device when viewed from the front can be maintained, and color changes within the viewing angle can be effectively suppressed. • Condition (1): ((PA-((AIN+AEX) / 2))×(PB-((BIN+BEX) / 2))) / (PA×PB) becomes 0.42 or more and 0.70 or less. • Condition (2): H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) each become 1.40 or more and 3.00 or less. [Example]

[0077] Hereinafter, the embodiments and comparative examples will be described.

[0078] The optical films of Examples 1 to 4 have the same shape as those described in the first embodiment above, and have a pyramidal lens portion 110 arranged in a matrix with equal spacing of 8.6 μm in both the first direction D1 and the second direction D2. The lens portion 110 is a regular pyramid, and the flat portion 111 is square. The low refractive index layer 102 is formed of a resin with a refractive index of 1.48, and the high refractive index layer 103 is formed of a resin with a refractive index of 1.65.

[0079] Next, the optical films of Examples 1 to 4 are formed such that the slope ratio determined by ((PA-((AIN+AEX) / 2))×(PB-((BIN+BEX) / 2))) / (PA×PB) is 0.42 or more and 0.70 or less, and the average aspect ratio in the first direction section view determined by H / ((AIN+AEX) / 2) and the average aspect ratio in the second direction section view determined by H / ((BIN+BEX) / 2) are 1.40 or more and 3.00 or less, respectively. Furthermore, since the lens portion 110 is a regular square pyramid, the average aspect ratio in the first direction section view and the average aspect ratio in the second direction section view are the same value. Hereinafter, when referred to simply as "average aspect ratio," it represents both the average aspect ratio in the first direction section view and the average aspect ratio in the second direction section view.

[0080] The optical film of Example 5 has the same shape as that described in the second embodiment above, and has a pyramidal lens portion 110 arranged in a matrix with equal spacing of 8.6 μm in both the first direction D1 and the second direction D2. The lens portion 110 is a regular pyramid, and the flat portion 111 is square. The low refractive index layer 102 is formed of resin with a refractive index of 1.48, and the high refractive index layer 103 is formed of resin with a refractive index of 1.65. The difference between Example 5 and Examples 1 to 4 is that in Examples 1 to 4, the high refractive index layer 103 is located on the light source (display panel) side, while in Example 5, the low refractive index layer 102 is located on the light source (display panel) side.

[0081] Furthermore, the optical thin film of Example 5 has a slope ratio of 0.42 or more and 0.70 or less, and an average aspect ratio that deviates from 1.40 or more and 3.00 or less.

[0082] Comparative Examples 1 to 4 have a regular square pyramidal lens portion, and the lens portions are arranged in a matrix with equal spacing of 8.6 μm in both the first direction D1 and the second direction D2. However, the slope ratio deviates from 0.42 to 0.70, and the average aspect ratio deviates from 1.40 to 3.00. In addition, the forming material is the same as that of the Examples. That is, the basic shape of Comparative Examples 1 to 4 is the same as that of Examples 1 to 4, but the slope ratio deviates from 0.42 to 0.70, and the average aspect ratio deviates from 1.40 to 3.00.

[0083] Furthermore, Comparative Examples 5 and 6 have a regular square pyramidal lens portion, and the lens portions are arranged in a matrix with equal spacing of 8.6 μm in both the first direction D1 and the second direction D2. However, the slope ratio deviates from 0.42 to 0.70 and the average aspect ratio deviates from 1.40 to 3.00. Moreover, the arrangement positions of the low refractive index layer and the high refractive index layer are reversed compared to Examples 1 to 4. Specifically, the low refractive index layer has a lens portion. That is, Comparative Examples 5 and 6 have a configuration in which the low refractive index layer and the high refractive index layer are arranged from the light source side ("L low high" in Table 1 below indicates that they are arranged in the order of low refractive index layer and high refractive index layer from the light source side). In addition, the forming materials are the same as those in Examples 1 to 5. Specifically, the basic shape of Comparative Examples 5 and 6 is the same as that of Example 5, but the slope ratio deviates from 0.42 to 0.70 and the average aspect ratio deviates from 1.40 to 3.00.

[0084] The evaluation of the embodiments and comparative examples was conducted from the viewpoints of brightness and color change. Brightness was evaluated by comparing the brightness (front brightness) of an image displayed on an OLED display panel with an optical film mounted in the front viewing direction with the front brightness of the same image displayed on an OLED display panel without an optical film mounted, and calculating the ratio of the former to the latter. Color change was evaluated by comparing the color change Δu'v' when viewing an image displayed on an OLED display panel without an optical film mounted at a 45-degree angle relative to the front viewing direction with the color change Δu'v' when viewing the same image displayed on an OLED display panel with an optical film mounted at a 45-degree angle relative to the front viewing direction.

[0085] When evaluating brightness and color change, a full-screen white image is displayed on the organic LED display panel. The Konica Minolta CS-1000 is used as the measuring device for brightness and color change.

[0086] The dimensional conditions, bevel ratio, average aspect ratio, frontal brightness ratio (%) of the optical thin film with / without the frontal surface, and color change values ​​of the embodiments and comparative examples are shown in Table 1 below. Furthermore, the bevels in the table correspond to the side surfaces. The lens portion is a regular square pyramid, but the side surfaces are curved, determining the curvature. Also, Figure 11 is a graph showing the frontal brightness ratio of the optical thin film with / without the frontal surface, and the color change values; the horizontal axis represents the frontal brightness ratio, and the vertical axis represents the color change values. Furthermore, the "high refractive index side exit width" in the table for Embodiment 5 corresponds to the symbol AIN (BIN) in Figure 10, and the "high refractive index side incident width" in the table for Embodiment 5 corresponds to the symbol AEX (BEX) in Figure 10. That is, the "high refractive index side exit width" and "high refractive index side incident width" in the table for Embodiment 5 are determined according to the definitions described in the first embodiment above. Furthermore, the "high refractive index side exit width" and "high refractive index side incident width" in the tables of Comparative Examples 5 and 6 are determined in the same way as in Example 5.

[0087]

[0088] Examples 1-4, as expressed by the color change suppression rate, show that the color change Δu'v' when viewed from a direction tilted at 45 degrees relative to the frontal viewing direction can be suppressed to less than 75% of the color change without the optical film. Furthermore, the brightness at this time is also more than 90% of the brightness without the optical film, suppressing the decrease in brightness when viewed from the front. The effects disclosed herein are confirmed by the results of these embodiments.

[0089] Furthermore, in Embodiment 5, the color change Δu'v' when viewed from a direction tilted at 45 degrees relative to the frontal viewing direction can be suppressed to less than 75% of the color change compared to the absence of an optical film. Moreover, although the slope ratio in Embodiment 5 is 0.51, it is also within the range of 0.42 to 0.70 spanned in Embodiments 1 to 4, suggesting a suitable color change suppression effect. Furthermore, the average aspect ratio of Embodiment 5 is 1.22. Although it deviates from 1.40 to 3.00, when it falls within the range of 1.40 to 3.00, since the area of ​​the side surface 110S is increased and the lens portion 110 is not excessively sharp, it is suggested that the effects of color change suppression and frontal brightness reduction suppression can be improved.

[0090] Furthermore, the straight line L in Figure 11 represents the tendency of the optical films of Comparative Examples 5 and 6 to form a low-refractive-index layer followed by a high-refractive-index layer from the light source side. Examples 1 to 4 are located below the straight line L, and their optical films are even better at suppressing color changes compared to those of Examples 5, Comparative Examples 5 and 6, which form a low-refractive-index layer followed by a high-refractive-index layer from the light source side. Based on this result, it is inferred that when the high-refractive-index layer 103 is located on the light source (display panel) side, an even higher color change suppression effect is obtained than when the low-refractive-index layer 102 is located on the light source (display panel) side.

[0091] [Simulation] In the first embodiment of the optical thin film 100, the high refractive index layer 103 facing the light source has a grid-shaped portion 103B, and the low refractive index layer 102 has a lens portion 110. In the simulation described below, the effectiveness of this configuration in the first embodiment is verified by comparing it with simulation comparative example X. In simulation comparative example X, a lens portion is provided in the high refractive index layer facing the light source, and the low refractive index layer deposited thereon forms a grid-shaped optical thin film.

[0092] The lens section 110 of the optical thin film 100, which is the object of simulation, is set with the following dimensional conditions. Furthermore, the high-refractive-index side exit width and the high-refractive-index side incident width are the same in both the first direction D1 and the second direction D2. • The lens section is a regular square pyramid. • Spacing: 8.6 μm (both in the first direction D1 and the second direction D2) • Average slope angle: 12.1 (°) • Slope radius of curvature: 15 (μm) • High-refractive-index side exit width: 1.8 (μm) • High-refractive-index side incident width: 3.1 (μm) • Height: 3 (μm) • Slope ratio: 51 (%) • Average aspect ratio: 1.22

[0093] The lens section of Comparative Example X was simulated, and the following dimensional conditions were set. The exit width on the high refractive index side and the incident width on the high refractive index side are the same in both the first direction D1 and the second direction D2. The lens section is a regular square pyramid. • Spacing: 8.6 μm (both in the first direction D1 and the second direction D2) • Average slope angle: 12.1 (°) • Slope radius of curvature: 15 (μm) • High refractive index side exit width: 5.5 (μm) • High refractive index side incident width: 6.8 (μm) • Height: 3 (μm) • Slope ratio: 8 (%) • Average aspect ratio: 0.48 *In addition, the "high refractive index side exit width" of the simulation comparative example X is calculated according to the definition described in the first embodiment above, based on the distance in the first direction D1 (second direction D2) between the flat portions 111 of the lens portions 110 adjacent in the first direction D1 (second direction D2). Similarly, the "high refractive index side incident wide side" of the simulated comparative example X is calculated according to the definition described in the first embodiment above, based on the distance in the first direction D1 (second direction D2) between the flat portion 111 of the lens portion 110 adjacent in the first direction D1 (second direction D2) and the end on the opposite side.

[0094] The simulation results calculate the color change Δu'v' relative to the frontal view at multiple viewing angles (45°, 30°, 15°) tilted relative to the frontal view. Table 2 below shows the simulation results.

[0095]

[0096] According to the simulation results above, the first embodiment shows the same color change at any viewing angle, and the degree of color change is even smaller than that of the simulation comparison example X, effectively suppressing color change. From the simulation results, it is confirmed that the grid-shaped portion 103B of the high refractive index layer 103 facing the light source side and the lens portion 110 of the low refractive index layer 102 are more effective in suppressing color change than the case where the lens portion is arranged in the high refractive index layer. [Simplified Explanation of the Diagram]

[0098] [Fig. 1] A schematic diagram showing the structure of a display device having the optical thin film of the first embodiment of the present disclosure. [Fig. 2] A partial perspective view of the optical thin film provided in the display device shown in Fig. 1. [Fig. 3] A schematic diagram showing the arrangement of the lens portions of the low refractive index layer of the optical thin film shown in Fig. 2. [Fig. 4] A cross-sectional view when the optical thin film is cut along line IV-IV of Fig. 3. [Fig. 5] A cross-sectional view when the optical thin film is cut along line VV of Fig. 3. [Fig. 6] A diagram showing a modified example of the optical thin film shown in Fig. 2. [Fig. 7] A diagram showing a modified example of the optical thin film shown in Fig. 2. [Fig. 8] A diagram showing a modified example of the optical thin film shown in Fig. 2. [Fig. 9] A diagram showing a modified example of the display device shown in Fig. 1. [Fig. 10] A schematic diagram showing the structure of a display device having the optical thin film of the second embodiment of the present disclosure. [Fig. 11] A diagram illustrating the relationship between the shape, brightness, and color change of the optical thin film of the embodiments and comparative examples.

Claims

1. An optical thin film comprising: a low-refractive-index layer including a plurality of lens portions, and a high-refractive-index layer disposed such that it fills the spaces between the plurality of lens portions, and having a refractive index higher than that of the low-refractive-index layer; each lens portion having a cylindrical shape tapering towards the high-refractive-index layer side, and having a flat portion at its front end on the high-refractive-index layer side parallel to the film surface of the optical thin film; the plurality of lens portions being arranged in two dimensions in a first direction parallel to the film surface and a second direction perpendicular to the first direction; the distance in the first direction between the flat portions of adjacent lens portions in the first direction is defined as AIN; the distance in the first direction between the ends opposite to the flat portions of adjacent lens portions in the first direction is defined as AEX; the distance in the first direction between the midpoints of adjacent lens portions in the first direction, i.e., the first-direction spacing, is defined as PA; and the distance in the second direction between the flat portions of adjacent lens portions in the second direction is defined as BIN. When the distance in the second direction between the ends opposite to the flat portion of the lens portion adjacent to the lens portion in the second direction is set as BEX; and when the distance in the second direction between the midpoints of the lens portions adjacent to the lens portion in the second direction, i.e. the second direction spacing, is set as PB, then ((PA-((AIN+AEX) / 2))×(PB-((BIN+BEX) / 2))) / (PA×PB) becomes 0.42 or more and 0.70 or less.

2. The optical thin film as described in claim 1, wherein, When the height of the aforementioned lens portion is set to H, the values ​​of H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) are both 1.40 or more and 3.00 or less.

3. An optical thin film comprising: a low-refractive-index layer including a plurality of lens portions, and a high-refractive-index layer disposed such that it fills the spaces between the plurality of lens portions, and having a refractive index higher than that of the low-refractive-index layer; each lens portion having a cylindrical shape tapering towards the high-refractive-index layer side, and having a flat portion at its leading end on the high-refractive-index layer side parallel to the film surface of the optical thin film; the plurality of lens portions being arranged in two dimensions in a first direction parallel to the film surface and a second direction perpendicular to the first direction; the distance between the flat portions of adjacent lens portions in the first direction is defined as AIN; the distance between the ends opposite to the flat portions of adjacent lens portions in the first direction is defined as AEX; the distance between the flat portions of adjacent lens portions in the second direction is defined as BIN; the distance between the ends opposite to the flat portions of adjacent lens portions in the second direction is defined as BEX; and the height of the lens portion is defined as H. H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) are respectively 1.40 or more and 3.00 or less.

4. The optical thin film as described in any one of claims 1 to 3, wherein, The aforementioned flat portion of the aforementioned lens is arranged facing the display panel side.

5. The optical thin film as described in any one of claims 1 to 4, wherein, The aforementioned complex lens sections are arranged in a matrix, and the aforementioned high refractive index layer includes a grid-shaped portion.

6. The optical thin film as described in any one of claims 1 to 5, wherein, The aforementioned lens portion is a square pyramid shape, and the aforementioned flat portion is a square shape.

7. The optical thin film as described in any one of claims 1 to 6, wherein, The aforementioned lens portion is a square pyramid shape, and the aforementioned flat portion is a rectangle.

8. The optical thin film as described in any one of claims 1 to 7, wherein, The side of the aforementioned lens portion is a curved surface that convexes from the aforementioned high refractive index layer.

9. An optical thin film comprising: a low-refractive-index layer including a plurality of lens portions, and a high-refractive-index layer disposed such that it fills the spaces between the plurality of lens portions, and having a refractive index higher than that of the low-refractive-index layer; each lens portion being a cylindrical shape tapering to one side in the normal direction of the film surface of the optical thin film, and having a flat portion parallel to the film surface at its front end on the aforementioned side; the plurality of lens portions being arranged in two dimensions in a first direction parallel to the film surface and a second direction perpendicular to the first direction; the distance in the first direction between the flat portions of adjacent lens portions in the first direction is defined as AIN; the distance in the first direction between the ends opposite to the flat portions of adjacent lens portions in the first direction is defined as AEX; the distance in the first direction between the midpoints of adjacent lens portions in the first direction, i.e., the first direction spacing, is defined as PA; and the distance in the second direction between the flat portions of adjacent lens portions in the second direction is defined as BIN. When the distance in the second direction between the ends opposite to the flat portion of the lens portion adjacent to the lens portion in the second direction is set as BEX; and when the distance in the second direction between the midpoints of the lens portions adjacent to the lens portion in the second direction, i.e. the second direction spacing, is set as PB, then ((PA-((AIN+AEX) / 2))×(PB-((BIN+BEX) / 2))) / (PA×PB) becomes 0.42 or more and 0.70 or less.

10. The optical thin film as described in claim 9, wherein, When the height of the aforementioned lens section is set to H, H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) are respectively 1.40 or more and 3.00 or less.

11. An optical thin film comprising: a low-refractive-index layer including a plurality of lens portions, and a high-refractive-index layer disposed such that it fills the spaces between the plurality of lens portions, and having a refractive index higher than that of the low-refractive-index layer; each lens portion being a cylindrical shape tapering to one side in the normal direction of the film surface of the optical thin film, and having a flat portion parallel to the film surface at its front end on the aforementioned side; the plurality of lens portions being arranged in two dimensions in a first direction parallel to the film surface and a second direction perpendicular to the first direction; the distance in the first direction between the flat portions of adjacent lens portions in the first direction is defined as AIN; the distance in the first direction between the ends opposite to the flat portions of adjacent lens portions in the first direction is defined as AEX; the distance in the second direction between the flat portions of adjacent lens portions in the second direction is defined as BIN; the distance in the second direction between the ends opposite to the flat portions of adjacent lens portions in the second direction is defined as BEX; and the height of the lens portion is defined as H. H / ((AIN+AEX) / 2) and H / ((BIN+BEX) / 2) are respectively 1.40 or more and 3.00 or less.

12. A display device comprising: an optical film as described in any one of claims 1 to 11; and an organic LED panel on which the optical film is disposed on a display surface.

13. A display device comprising: an optical thin film as described in any one of claims 1 to 11; and a liquid crystal panel on which the optical thin film is disposed on a display surface.

14. A polarizing plate with an optical thin film, comprising: an optical thin film as described in any one of claims 1 to 11; and a polarizing plate bonded to the aforementioned optical thin film.

Images