Optical film, polarizing plate with optical film, and display device

Abstract

The optical film of the embodiment comprises a substrate (101), a front member (102) disposed on the front side of the substrate (101), and an optical functional layer (103) disposed on the back side of the substrate (101), wherein the optical functional layer (103) comprises a low refractive index layer (104) and a high refractive index layer (105), and the interface between the low refractive index layer (104) and the high refractive index layer (105) is concavoconvex. Furthermore, the refractive indexes of the high refractive index layer (105), the substrate (101), and the front member (102) are successively smaller.

Description

Technical Field

[0001] The present invention relates to an optical film that performs an optical effect on light emitted from a display surface of a display device, and also to a polarizing plate with an optical film and a display device having the optical film. Background Art

[0002] Liquid crystal display devices, which are an example of display devices, are used in various fields. In addition, organic LED (Organic Light Emitting Diode) display devices are also becoming popular in recent years.

[0003] In a liquid crystal display device, the color tone of an image within a viewing angle may change significantly due to changes in light intensity depending on the viewing angle, light leakage in an oblique direction, and the like.

[0004] On the other hand, in an organic LED display device, a blue shift is likely to occur in an image viewed from an oblique direction. Blue shift refers to a phenomenon in which an image viewed from an oblique direction becomes bluer than an image viewed from the front. That is, in an image displayed by an organic LED display device, for example, there is a case where the color tone within the viewing angle changes significantly due to such a blue shift. It should be noted that the blue shift is likely to become particularly significant in an organic LED display device using a microcavity structure.

[0005] The color change within the viewing angle as described above is the main reason that may reduce the display quality of the image. As other factors affecting the display quality, for example, the deviation of the contrast within the viewing angle can also be cited. In the past, various technologies for improving the display quality of the image have been proposed, for example, in Japanese Patent Publication No. 7-43704, Japanese Patent No. 3272833, Japanese Patent No. 3621959, Japanese Patent Publication No. 2016-126350, Japanese Patent Publication No. 2012-145944, Japanese Patent Publication No. 2011-118393 and U.S. Patent Publication No. 9507059, an optical film provided on the display surface of a display device in order to improve the display quality of the image is disclosed.

[0006] Generally, optical films used to improve the display quality of images have a multilayer structure. However, in such a multilayer structure, due to reflections at the interface between layers, reflections at the interface with the air layer, and absorption of light at each layer, the energy of light taken out to the outside is reduced. Therefore, for example, the power consumption for obtaining the desired brightness may increase unexpectedly. Summary of the invention

[0007] The present invention has been completed in consideration of the above-mentioned actual situation, and its purpose is to provide an optical film that can fully suppress the energy loss of light forming an image while improving the display quality of the image within the viewing angle, a polarizing plate with an optical film having the optical film, and a display device.

[0008] The optical film of the present invention comprises: a substrate; a front member, which is arranged on the front side of the substrate; and an optical functional layer, which is arranged on the back side of the substrate, the optical functional layer having: a first layer; and a second layer having a refractive index different from that of the first layer, which is bonded to the first layer on the substrate side of the first layer, the first interface between the first layer and the second layer is concave-convex, and the refractive indices of the second layer, the substrate and the front member respectively become smaller in sequence.

[0009] The refractive index of the first layer may be smaller than the refractive index of the second layer.

[0010] The refractive index of the first layer may be greater than the refractive index of the second layer.

[0011] The concave portion and the convex portion in the concavo-convex shape may each have a flat portion extending along the film surface of the optical film.

[0012] The difference in refractive index between the second layer and the substrate, and the difference in refractive index between the substrate and the front member may be 0.2 or less, preferably 0.1 or less in absolute value.

[0013] The refractive index of the front member may be 1.40 or less, preferably 1.37 or less.

[0014] The refractive index of the front member may be 1.37 or less, the refractive index of the substrate may be 1.38 or more and 1.57 or less, and the refractive index of the second layer may be 1.58 or more. Preferably, the refractive index of the front member is 1.37 or less, the refractive index of the substrate is 1.43 or more and 1.51 or less, and the refractive index of the second layer is 1.58 or more and 1.65 or less.

[0015] Furthermore, the refractive index of the front member may be 1.28 or less, the refractive index of the substrate may be 1.47 to 1.54, and the refractive index of the second layer may be 1.6 or more.

[0016] The optical function layer may further include a third layer stacked on the first layer on the opposite side of the second layer, the first layer and the third layer may have different refractive indices, and a second interface between the first layer and the third layer may have a concavo-convex shape.

[0017] The refractive index of the first layer may be smaller than the refractive index of the third layer.

[0018] The refractive index of the first layer may be greater than the refractive index of the third layer.

[0019] The pitch of the concavities and convexities of the concavo-convex shape of the first interface may be larger than the pitch of the concavo-convexities of the concavo-convex shape of the second interface.

[0020] A coloring material may be provided on the second layer side relative to the first interface.

[0021] The optical function layer may further include a colored layer laminated on the second layer side of the optical function layer, wherein the colored material is included in the colored layer.

[0022] The coloring material may be contained in the coloring layer in a ratio of 1.0 mass % to 5.0 mass % both inclusive.

[0023] The colored piece may be black.

[0024] In the optical film, the first layer may have adhesiveness.

[0025] Furthermore, a display device of the present invention includes the optical film and a liquid crystal panel, wherein the optical film is arranged so that the first layer faces a display surface side of the liquid crystal panel relative to the second layer.

[0026] Furthermore, another display device of the present invention includes the optical film and an organic LED panel, wherein the optical film is arranged so that the first layer faces a display surface side of the organic LED panel relative to the second layer.

[0027] Moreover, the polarizing plate with an optical film of the present invention is a polarizing plate with an optical film including the above-mentioned optical film and a polarizing plate bonded to the above-mentioned optical film.

[0028] In the polarizing plate with an optical film, the layer of the optical film in contact with the polarizing plate may also serve as an adhesive layer for bonding to the polarizing plate. In addition, an adhesive layer may be further provided between the optical film and the polarizing plate.

[0029] The polarizing plate with an optical film of the present invention may include: the optical film; a polarizer bonded to the optical film; and an adhesive layer bonding the optical film and the polarizer, wherein the polarizer is bonded to the optical film only via the adhesive layer.

[0030] Alternatively, the polarizing plate with an optical film of the present invention may include the optical film and a polarizer bonded to the optical film, wherein a layer of the optical film in contact with the polarizer also serves as an adhesive layer bonded to the polarizer, and the polarizer is directly bonded to the optical film.

[0031] According to the present invention, it is possible to improve the display quality of an image within a viewing angle while sufficiently suppressing the energy loss of light forming an image. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a diagram schematically showing the structure of a display device including the optical film according to the first embodiment of the present invention.

[0033] Figure 2 is set at Figure 1 An enlarged cross-sectional view of an optical film of a display device is shown.

[0034] Figure 3 This is a diagram for explaining a method for calculating the energy transmittance of light that passes through a multilayer structure.

[0035] Figure 4 It is shown in Figure 1 A graph showing the calculated energy transmittance of light transmitted through the display device is shown.

[0036] Figure 5 is shown for the setting Figure 1 FIG. 1 is a graph illustrating the relationship between the refractive index of the front member in the optical film of the display device shown and the energy transmittance of light passing through the optical film.

[0037] Fig. 6A is shown for the setting Figure 1 FIG. 1 is a graph illustrating the relationship between the refractive index of a substrate in an optical film of a display device shown in FIG. 1 and the energy transmittance of light passing through the optical film.

[0038] Figure 6B is shown for the setting Figure 1 FIG. 1 is a graph illustrating the relationship between the refractive index of a substrate in an optical film of a display device shown in FIG. 1 and the energy transmittance of light passing through the optical film.

[0039] Figure 7 This is a diagram schematically showing the structure of a display device including an optical film according to a second embodiment of the present invention.

[0040] Figure 8 This is a diagram schematically showing the structure of a display device including an optical film according to a third embodiment of the present invention.

[0041] Fig. 9 It is a perspective view showing the structure of an optical film according to a fourth embodiment of the present invention.

[0042] Fig.10 yes Fig. 9 A cross-sectional view of the optical film along line XX.

[0043] Fig.11This is a diagram for explaining the effect of image light from a display device incident on the optical film according to the fourth embodiment.

[0044] Fig.12 This is a graph showing the distribution of normalized brightness with respect to the viewing angle of examples and comparative examples of the optical film according to the fourth embodiment.

[0045] Fig.13 It is a perspective view showing the structure of an optical film according to a fifth embodiment of the present invention.

[0046] Fig.14 yes Fig.13 A cross-sectional view of the optical film along line XIV-XIV.

[0047] Fig.15 This is a diagram for explaining the effect of image light from a display device incident on the optical film according to the fifth embodiment.

[0048] Fig.16 This is a diagram for explaining the effect of light from outside that is incident on the optical film according to the fifth embodiment.

[0049] Fig.17 is a cross-sectional view showing a modified example of the optical film.

[0050] Fig.18 The diagrams show modified examples of the lens portion of the optical film according to each embodiment.

[0051] Fig.19 It is a figure which shows the state which bonded the polarizing plate to the optical film.

[0052] Fig. 20 It is a figure which shows the state which bonded the polarizer to the optical film. DETAILED DESCRIPTION

[0053] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0054] It should be noted that, in this specification, the terms such as "sheet", "film", "plate", "layer" and the like are not distinguished from each other based only on the difference in name. Therefore, for example, "sheet" is a concept that also includes components that can also be called films, plates, and layers. In addition, in this specification, "sheet surface (plate surface, film surface)" refers to a surface that is consistent with the plane direction (surface direction) of the sheet component as the object when the sheet component as the object is observed as a whole and in a large area. And, in this specification, the normal direction of the sheet component refers to the normal direction of the sheet component as the object relative to the sheet surface.

[0055] <<First embodiment>>

[0056] Figure 1This is a diagram schematically showing the structure of a display device 10 including an optical film 100 according to the first embodiment of the present invention. Figure 2 is an enlarged cross-sectional view of the optical film 100 . Figure 1 The display device 10 shown is a liquid crystal display device, which is composed of a surface light source device 20, a liquid crystal panel 15 and an optical film 100 stacked in sequence. As an example, the display device 10 of this embodiment is configured as a television, but it can also be a tablet terminal, a smart phone, a computer display, a car navigation system, etc.

[0057] exist Figure 1 In the drawings used in the following description, reference numeral D1 indicates a first direction which is parallel to the film surface of the optical film 100. Reference numeral D2 indicates a second direction which is parallel to the film surface of the optical film 100 and orthogonal to the first direction D1. In addition, reference numeral D3 indicates a third direction which is orthogonal to both the first direction D1 and the second direction D2.

[0058] like Figure 2 As shown, the optical film 100 of this embodiment has a plurality of lens portions 110 arranged at intervals, and each lens portion 110 extends in a strip shape in a direction orthogonal to the arrangement direction, and the details are described later. In this embodiment, the arrangement direction of the lens portion 110 is consistent with the first direction D1, and the long side direction of the lens portion 110 is consistent with the second direction D2. The first direction D1 and the second direction D2 may be consistent with the row direction and column direction of the pixel area arranged in a matrix in the liquid crystal panel 15, or may not be consistent. In the case of considering the suppression of moire fringes, the first direction D1 and the second direction D2 are generally made inconsistent with the row direction and column direction of the pixel area arranged in a matrix.

[0059] (LCD Panel)

[0060] The liquid crystal panel 15 has a display surface 15A for displaying an image (hereinafter referred to as an image) as a static image or a dynamic image, and a back surface 15B arranged opposite to the display surface 15A. In the display device 10, the liquid crystal panel 15 functions as a shutter that controls the transmission or blocking of light from the surface light source device 20 for each area (sub-pixel) forming a pixel, and displays an image on the display surface 15A by driving the liquid crystal panel 15.

[0061] The illustrated liquid crystal panel 15 includes an upper polarizing plate 13 disposed on the light emitting side, a lower polarizing plate 14 disposed on the light incident side, and a liquid crystal layer 12 disposed between the upper polarizing plate 13 and the lower polarizing plate 14. The polarizing plates 14 and 13 have the following functions: decomposing incident light into two orthogonal polarization components (e.g., p-wave and s-wave), transmitting a linear polarization component (e.g., p-wave) vibrating in one direction (a direction parallel to the transmission axis), and absorbing a linear polarization component (e.g., s-wave) vibrating in another direction (a direction parallel to the absorption axis) orthogonal to the one direction.

[0062] In the liquid crystal layer 12, a voltage can be applied to each region forming a pixel, and the orientation direction of the liquid crystal molecules in the liquid crystal layer 12 changes depending on whether a voltage is applied. As an example, the polarization component in a specific direction passing through the lower polarizing plate 14 arranged on the light incident side has its polarization direction rotated 90° when passing through the liquid crystal layer 12 to which no voltage is applied, and on the other hand, maintains its polarization direction when passing through the liquid crystal layer 12 to which a voltage is applied. In this case, depending on whether a voltage is applied to the liquid crystal layer 12, it is possible to control whether the polarization component vibrating in a specific direction passing through the lower polarizing plate 14 further passes through the upper polarizing plate 13 arranged on the light exit side of the lower polarizing plate 14, or whether it is absorbed by the upper polarizing plate 13 and blocked. In this way, in the liquid crystal panel 15, the transmission or blocking of light from the surface light source device 20 can be controlled for each region forming a pixel.

[0063] In the present embodiment, as an example, the liquid crystal panel 15 is a VA (Vertical Alignment) type liquid crystal panel. Therefore, when the voltage applied to the liquid crystal molecules in the liquid crystal layer 12 is off or at a minimum value, the liquid crystal panel 15 is in a state where the liquid crystal molecules are oriented along the normal direction of the display surface 15A, so that the light from the surface light source device 20 is blocked. The liquid crystal panel 15 has the following structure: by gradually increasing the voltage applied to the liquid crystal molecules, the liquid crystal molecules are gradually tilted toward one side along the display surface 15A, thereby gradually increasing the transmittance of the light from the surface light source device 20. In addition, the liquid crystal panel 15 is not limited to the VA type, and may also be a TN (Twisted Nematic) type liquid crystal panel, or an IPS (In-Plane Switching) type liquid crystal panel.

[0064] (Surface light source device)

[0065] The surface light source device 20 has a light emitting surface 21 that emits light in a planar manner. In the present embodiment, the surface light source device 20 is used as a device for illuminating the liquid crystal panel 15 from the back 15B side. As an example, the surface light source device 20 is an edge light type surface light source device, but it can also be a direct type or a back irradiation type.

[0066] (Optical Film)

[0067] The optical film 100 is disposed on the display surface 15A of the liquid crystal panel 15. Specifically, the optical film 100 is bonded to the display surface 15A. Figure 2 The optical film 100 comprises: a sheet-like or film-like substrate 101 having a front surface 101A and a back surface 101B on the opposite side thereof; a sheet-like or film-like front member 102 disposed on the front surface 101A of the substrate 101; and a sheet-like or film-like optical functional layer 103 disposed on the back surface 101B of the substrate 101. The optical functional layer 103 comprises a low refractive index layer 104 corresponding to the first layer and a high refractive index layer 105 corresponding to the second layer.

[0068] The substrate 101 is a transparent substrate with light transmittance composed of resin, glass, etc., and its material can be, for example, polyethylene terephthalate, polyolefin, polycarbonate, polyacrylate, polyamide, glass, triacetyl cellulose, polyimide, polyethylene naphthalate, etc. The refractive index of the substrate 101 is preferably in the range of 1.38 or more and 1.57 or less, and more preferably 1.47 or more and 1.54 or less. In addition, the thickness of the substrate 101 is preferably 5 μm or more and 120 μm or less. From the perspective of operability, the lower limit of the thickness of the substrate 101 is preferably 15 μm or more, and more preferably 25 μm or more. From the perspective of thin filmization, the upper limit of the thickness of the substrate 101 is preferably 150 μm or less. The substrate 101 is preferably colorless and transparent. In addition, the total light transmittance of the substrate 101 is preferably 87% or more, and more preferably 90% or more.

[0069] As described above, the optical function layer 103 includes the low refractive index layer 104 and the high refractive index layer 105. The refractive index of the low refractive index layer 104 is lower than that of the high refractive index layer 105, and the high refractive index layer 105 is bonded to the low refractive index layer 104 on the substrate 101 side of the low refractive index layer 104. The high refractive index layer 105 has a plurality of lens portions 110 on the surface on the side opposite to the substrate 101 side. The lens portion 110 is formed so as to protrude toward the low refractive index layer 104 side in the normal direction of the high refractive index layer 105, that is, along the third direction D3. That is, the high refractive index layer 105 integrally includes: a film-like layer body 105A having a front surface facing the substrate 101 side and a back surface on the opposite side of the surface; and a plurality of lens portions 110 arranged on the back surface of the layer body 105A. In contrast, the low refractive index layer 104 is stacked on the high refractive index layer 105 in a manner that covers the lens portion 110 and fills between the plurality of lens portions 110. Thus, in the present embodiment, the interface between the low refractive index layer 104 and the high refractive index layer 105 is formed into a concavo-convex shape 120. In addition, the optical film 100 is configured such that the low refractive index layer 104 faces the display surface 15A side of the liquid crystal panel 15 relative to the high refractive index layer 105.

[0070] The concavoconvex shape 120 is configured as follows: a shape of one cycle is formed by one concave portion 121 and a convex portion 122, and the shape of one cycle is repeatedly formed. In addition, in the present embodiment, the portion that is concave toward the high refractive index layer 105 side with respect to a reference line SL that passes through the midpoint of the bottom of the concave portion 121 and the top of the convex portion 122 and extends along the film surface direction of the optical film 100 corresponds to the concave portion 121, and the portion that is convex toward the low refractive index layer 104 side with respect to the reference line SL corresponds to the convex portion 122. In the present embodiment, the concave portion 121 and the convex portion 122 are respectively arranged along the first direction D1, and extend linearly along the second direction D2 orthogonal to the first direction D1.

[0071] In addition, the concave portion 121 and the convex portion 122 of the present embodiment respectively have flat portions 121A and 122A extending along the film surface of the optical film 100. In detail, the bottom of the concave portion 121 becomes the flat portion 121A, and the top of the convex portion 122 becomes the flat portion 122A. In addition, the side surface 120S of the concave-convex shape 120 extending between the flat portion 121A of the concave portion 121 and the flat portion 122A of the convex portion 122 becomes a curved surface convex to the low refractive index layer 104 side. The side surface 120S is formed to not cross the straight line extending along the third direction D3 from the end point of the flat portion 121A connected thereto in the film surface direction. Thus, the high refractive index layer 105 having the lens portion 110 forming the side surface 120S can be demolded.

[0072] It should be noted that, in the present embodiment, the side surface 120S is a curved surface, but the side surface 120S may also be a folded surface (polygonal shape) convex toward the low refractive index layer 104 side. In addition, the side surface 120S formed as a curved surface may also be formed along the arc of a perfect circle, or may also be formed along the arc of an ellipse. In addition, the side surface 120S may also be a curved surface or a folded surface recessed toward the high refractive index layer 105 side, or may be a plane.

[0073] The above-mentioned concavoconvex shape 120 produces optical effects such as total reflection or refraction, and transmission on the light emitted from the display surface 15A for forming an image, thereby improving the display quality of the image displayed on the display surface 15A. In the present embodiment, the two side surfaces 120S adjacent to each other are formed in a shape that tapers toward the direction in which the concave portion 121 is recessed or the direction in which the convex portion 122 protrudes. In other words, the side surface 120S adjacent to the flat portion 121A of the concave portion 121 is formed in a shape that tapers from the low refractive index layer 104 side toward the high refractive index layer 105 side, and the side surface 120S adjacent to the flat portion 122A of the convex portion 122 is formed in a shape that tapers from the high refractive index layer 105 side toward the low refractive index layer 104 side. In the case of such a shape, an optical effect is produced to improve the display quality of the image displayed on the display surface 15A, but if the side surface 120S is a curved surface or polygonal shape convex toward the low refractive index layer 104 side as in the present embodiment, the color change within the viewing angle can be particularly effectively suppressed.

[0074] In the present embodiment, the low refractive index layer 104 and the high refractive index layer 105 are selected in such a way that the difference between the refractive index of the low refractive index layer 104 and the refractive index of the high refractive index layer 105 is within the range of more than 0.05 and less than 0.60. The difference between the refractive index of the low refractive index layer 104 and the refractive index of the high refractive index layer 105 is preferably more than 0.05 and less than 0.50, more preferably more than 0.10 and less than 0.20. In addition, the refractive index of the low refractive index layer 104 is, for example, more than 1.40 and less than 1.55. The refractive index of the high refractive index layer 105 is, for example, more than 1.55 and less than 1.90, which is larger than the refractive index of the low refractive index layer 104.

[0075] The low refractive index layer 104 can be formed by, for example, curing an ultraviolet curing resin, an electron beam curing resin, or a thermosetting resin. When the low refractive index layer 104 is formed by curing an ultraviolet curing resin, the ultraviolet curing resin can include an acrylic resin or an epoxy resin. In addition, it can also be formed by, for example, curing an ultraviolet curing resin, an electron beam curing resin, or a thermosetting resin in the same manner as the high refractive index layer 105. When the high refractive index layer 105 is formed by curing an ultraviolet curing resin, the ultraviolet curing resin can include an acrylic resin or an epoxy resin. In addition, the low refractive index layer 104 can also be an adhesive such as an acrylic adhesive.

[0076] The thickness of the layer body 105A in the high refractive index layer 105 in the third direction D3 is, for example, 0.5 μm to 30 μm. The height of the lens portion 110 is, for example, 1.0 μm to 30 μm. On the other hand, the thickness of the low refractive index layer 104 is 5 μm to 100 μm.

[0077] In this embodiment, the high refractive index layer 105 is directly bonded to the substrate 101. On the other hand, the optical film 100 may also have a flat layer between the high refractive index layer 105 and the substrate 101, and the high refractive index layer 105 is bonded to the substrate 101 via the flat layer. The flat layer is a layer for stabilizing the bonding state of the high refractive index layer 105 and the substrate 101. The flat layer is composed of a transparent material with light transmittance, and in particular, in this embodiment, it is composed of a material that can transmit visible light and ultraviolet rays, for example, it can contain polyester resin, vinyl chloride / vinyl acetate resin, polyurethane resin, etc. as the main component. The main component refers to a component that contains 50% or more of the mass of the components constituting a substance or a component that contains the most in the components constituting the substance. The flat layer can be formed, for example, by drying a solution of a polyester resin, a vinyl chloride / vinyl acetate resin, or a urethane resin. The thickness of the flat layer is, for example, greater than 1 μm and less than 20 μm. In addition, the refractive index of the flat layer is, for example, greater than 1.46 and less than 1.67.

[0078] The refractive index of the flat layer is preferably the same as that of the high refractive index layer 105, or the difference between its refractive index and that of the high refractive index layer 105 is 0.08 or less, or the same as that of the substrate 101, or the difference between its refractive index and that of the substrate 101 is 0.08 or less, or the average value M of the refractive index of the high refractive index layer 105 and the refractive index of the substrate 101 or 0.98 to 1.02M.

[0079] In addition, when the layer of the optical film 100 that is in contact with the upper polarizing plate 13 (here, the low refractive index layer 104) is an adhesive layer, the low refractive index layer 104 is directly bonded to the display surface 15A of the liquid crystal panel 15, more specifically, to the front surface of the upper polarizing plate 13. In addition, the low refractive index layer 104 can also be bonded to the surface of the upper polarizing plate 13 through an adhesive layer provided on the display surface 15A of the liquid crystal panel 15 (i.e., provided between the display surface 15A and the front surface of the upper polarizing plate 13).

[0080] On the other hand, the front member 102 is the most front part constituting the optical film 100, and when assembled in the display device 10, it constitutes the most front part of the display device 10. The front member 102 basically functions as a protective layer, and on the other hand, its refractive index is set to be less than 1.40. By having such a low refractive index, the front member 102 can improve the performance of extracting light emitted from the optical film 100 to the outside.

[0081] The improvement of the light extraction performance toward the outside based on the front element 102 is achieved by setting the refractive index of the front element 102 to a low value of 1.40 or less. When the refractive index of the front element 102 is low, the critical angle at which the light intended to be emitted from the liquid crystal panel 15 side to the outside starts to be totally reflected at the interface between the front element 102 and the air becomes larger. As a result, the amount of light extracted increases, and the situation where the brightness within the viewing angle is unexpectedly reduced is suppressed.

[0082] The critical angle at the interface of the front part 102 and the air when the refractive index of the front part 102 is below 1.40 is more than 45.56 degrees. More specifically, when the refractive index is 1.36, the critical angle is 47.3 degrees, when the refractive index is 1.32, the critical angle is 49.2 degrees, when the refractive index is 1.28, the critical angle is 51.26 degrees, and when the refractive index is 1.26, the critical angle is 52.52 degrees. That is, the lower the refractive index of the front part 102, the more the light extraction performance toward the outside is improved. In addition, when the refractive index of the front part 102 is relatively low, external light is easily incident on the front part 102, thereby also being able to improve the anti-reflection performance for external light, and also being able to improve visual recognition.

[0083] The structure and material of the front member 102 are not particularly limited, and examples of the structure include a low-refractive index single-layer structure, a two-layer or three-layer dielectric multilayer structure, and a hollow particle or porous structure.

[0084] When the structure of the front member 102 is a low-refractive index single-layer structure, it goes without saying that the refractive index of the single layer becomes the refractive index of the front member 102. The measurement of the refractive index when the structure of the front member 102 is a low-refractive index single-layer structure can be obtained by, for example, fitting the reflection spectrum measured by a spectrophotometer with the spectrum calculated by the optical model of the film using the Fresnel formula. In addition, the refractive index can also be measured by an Abbe refractometer (NAR-4T manufactured by Atago) or an ellipsometer.

[0085] In addition, the refractive index of the front member 102 can also be measured through the following steps.

[0086] That is, the front piece 102 is shaved off with a cutter or the like to prepare a powdered sample, and the Baker method according to JIS K 7142 (2008) B method (for powdered or granular transparent materials) is used (using a Cargill reagent with a known refractive index, the powdered sample is placed on a slide glass or the like. The reagent is dripped onto the sample to immerse the sample in the reagent. This is observed under a microscope, and the refractive index of the reagent, which is a bright line (Becke line) produced on the outline of the sample and cannot be visually observed due to the difference in refractive index between the sample and the reagent, is taken as the refractive index of the sample.).

[0087] In addition, when the structure of the front element 102 is a low refractive index single-layer structure, the thickness of the front element 102 is preferably 0.07 μm or more and 0.12 μm or less. From the viewpoint of preventing reflection, the thickness of the front element 102 is preferably as small as possible, preferably 0.075 μm or more and 0.11 μm or less. In addition, as the material of the front element 102 in the low refractive index single-layer structure, magnesium fluoride, acrylic resin, etc. can be cited.

[0088] In addition, when the structure of the front member 102 is a dielectric multilayer structure such as two layers or three layers, in the present embodiment, the refractive index of the layer with the lowest refractive index is determined as the refractive index of the front member 102. In addition, in the dielectric multilayer structure, multiple layers with different refractive indices are stacked. The measurement of the refractive index can be obtained by the following method: the refractive index of the layer with the lowest refractive index is determined by fitting the reflection spectrum measured by a spectrophotometer and the spectrum calculated by the optical model of the film using the Fresnel formula. In addition, the refractive index of the layer with the lowest refractive index can also be obtained by measuring using an Abbe refractometer (NAR-4T manufactured by Atago Co., Ltd.) or an ellipsometer.

[0089] In addition, the refractive index of the front member 102 can also be measured through the following steps.

[0090] That is, the layer with the lowest refractive index in the front member 102 is shaved off with a cutter or the like to prepare a powdered sample, and the Baker method according to JIS K 7142 (2008) B method (for powdered or granular transparent materials) is used (using a Cargill reagent with a known refractive index, the powdered sample is placed on a slide glass or the like. The reagent is dripped onto the sample and the sample is immersed in the reagent. This is observed under a microscope, and the refractive index of the reagent, which is a bright line (Becke line) produced on the contour of the sample and cannot be visually observed due to the difference in refractive index between the sample and the reagent, is taken as the refractive index of the sample.).

[0091] In addition, when the structure of the front member 102 is a dielectric multilayer structure, the thickness of the front member 102 is preferably 0.1 μm or more and 1.4 μm or less. From the viewpoint of preventing reflection, the thickness of the front member is preferably as small as possible, and in the case of a dielectric multilayer structure, it is preferably 0.1 μm or more and 1.2 μm or less.

[0092] As the material of the front member 102 in the case of a three-layer dielectric multilayer structure, when the refractive indices of the first, second and third layers stacked from the inside to the outside are set to nA, nB and nC, they generally satisfy the relationship of nA<nB and nB>nC.

[0093] In addition, when the structure of the front member 102 is a hollow particle or a porous structure, the front member 102 may contain, for example, hollow silica particles and a base resin for retaining the hollow silica particles. The front member 102 may also be composed of, for example, a porous film having a plurality of air holes that can be formed using a sol-gel method. The refractive index of the front member 102 when it is a hollow particle or a porous structure can be determined by an average refractive index. The average refractive index can be calculated by the following method: for example, the occupancy rate of the air portion and the occupancy rate of other portions are determined using an SEM image, and the value obtained by multiplying the refractive index of air, that is, 1, by the occupancy rate of the air portion and the value obtained by multiplying the refractive index of other portions by the occupancy rate of other portions are added to calculate the average refractive index.

[0094] When the front member 102 has a hollow particle or porous structure, the thickness of the front member 102 is preferably 0.1 μm to 14 μm. From the viewpoint of preventing reflection, the thickness of the front member is preferably as small as possible, preferably 0.1 μm to 12 μm.

[0095] In the case where the front member 102 contains hollow silica particles and a base resin for retaining the hollow silica particles, the base resin may be, for example, a (meth) acrylic resin. In addition, in the case where the front member 102 is a porous structure, its material may also be a resin with a low refractive index, such as a fluororesin, an organic polysiloxane, etc. It should be noted that, in the case where the structure of the front member 102 is a hollow particle or a porous structure, the front member 102 may be a single layer, or may include a layer having a hollow particle or a porous structure and other layers (a hard layer, a high refractive index layer).

[0096] <Relationship of refractive index in optical films>

[0097] Next, the relationship between the refractive indexes of the plurality of layers of the optical film 100 will be described.

[0098] In this embodiment, the refractive index of each layer is set in such a way that the refractive index of each layer in the optical functional layer 103 becomes smaller in sequence. The inventors of the present application have conducted in-depth research and found that when the refractive index of the high refractive index layer 105, the substrate 101, and the front member 102 arranged in the direction in which light is emitted to the outside gradually decreases toward the outside, light can be efficiently extracted to the outside.

[0099] In this way, when the refractive index of each of the high refractive index layer 105, the substrate 101 and the front member 102 becomes smaller in sequence, from the viewpoint of improving the light extraction performance, it is preferred that the refractive index of each of the high refractive index layer 105, the substrate 101 and the front member 102 be changed in the same proportion or smoothly. In detail, the difference between the refractive index difference between the high refractive index layer 105 and the substrate 101 and the difference between the refractive index difference between the substrate 101 and the front member 102 is preferably 0.2 or less in absolute value, particularly preferably 0.1 or less, more preferably 0.05 or less, further preferably 0.02 or less, and further preferably 0.

[0100] When the refractive indices of the high refractive index layer 105, the substrate 101, and the front member 102 are successively reduced as described above, it can be visually confirmed that light is easily allowed to pass through, compared with (1) Comparative Structure 1: the refractive index of the high refractive index layer 105 is higher than that of the substrate 101, but the refractive index of the substrate 101 is lower than that of the front member 102, and (2) Comparative Structure 2: the refractive index of the high refractive index layer 105 is lower than that of the substrate 101, and the refractive index of the substrate 101 is higher than that of the front member 102.

[0101] Specifically, if a comparison is made between a situation in which an image from a liquid crystal panel 15 is visually confirmed through the optical film 100 of an embodiment configured on the liquid crystal panel 15 and a situation in which the same image is visually confirmed through the optical film of the comparison structure 1 or the comparison structure 2, it is easily recognizable that the former is brighter than the latter even by visual observation when observed over the entire viewing angle.

[0102] In addition, the fact that the amount of light extracted increases by setting the refractive index of each layer as described above can also be confirmed by calculating the energy transmittance of p-wave and s-wave light.

[0103] Figure 3 This is a diagram for explaining a method for calculating the energy transmittance of light passing through a multilayer structure. Figure 3 In FIG. 1 , a light incident at an incident angle α partially enters a layer of a refractive index n2 from a layer of a refractive index n1, and another part is reflected. The reflection angle of the reflected light becomes the same angle as the incident angle α. In addition, the light incident on the layer of a refractive index n2 travels at a refraction angle β.

[0104] When the light is reflected as described above, the amplitude transmittance tp of the p-wave light and the amplitude transmittance ts of the s-wave light are expressed by the following equations (1) and (2).

[0105] [Number 1]

[0106]

[0107]

[0108] The relationship between the incident angle α and the refraction angle β is expressed by the following equation (3) based on Snell's law.

[0109] [Number 2]

[0110] n1sinα=n2sinβ…(3)

[0111] Furthermore, since the energy of light is proportional to the square of the amplitude of the electric field, the energy transmittance of light is calculated by the square of the amplitude transmittance. However, in this case, it is necessary to consider the refractive index difference between the two layers as a coefficient. Based on this relationship, the energy transmittance Tp of p-wave light and the energy transmittance Ts of s-wave light are expressed as the following equations (4) and (5) using the above equations (1) to (3).

[0112]

[0113]

[0114] In the optical film 100 of the present embodiment, the low refractive index layer 104, the high refractive index layer 105, the substrate 101 and the front member 102 are stacked in order. In this case, the energy transmittance between the low refractive index layer 104 and the high refractive index layer 105, the energy transmittance between the high refractive index layer 105 and the substrate 101, the energy transmittance between the substrate 101 and the front member 102, and the energy transmittance between the front member 102 and the air are obtained respectively, and all of them are multiplied together, thereby calculating the energy transmittance of light of the optical film 100.

[0115] In the following calculation examples 1 to 9, calculation results of energy transmittance of the optical film 100 of the embodiment under various conditions and calculation results of energy transmittance of the optical film of comparative structures 1 and 2 are shown. In calculation examples 10 to 15 and calculation examples 16 to 20, calculation results of energy transmittance of the optical film 100 of the embodiment under conditions different from those of calculation examples 1 to 9 are shown. In the following calculation results, energy transmittance of light incident from the low refractive index layer 104 to the high refractive index layer 105 at incident angles of 0.01 degrees, 20 degrees, and 40 degrees among the light transmitted in the display device is calculated. Figure 4 The calculated energy transmittance of light is shown.

[0116] (Calculation Example 1)

[0117] In calculation example 1, in the optical film 100 of this embodiment, the refractive index of the low refractive index layer 104 is 1.48, the refractive index of the high refractive index layer 105 is 1.65, the refractive index of the substrate 101 is 1.49, the refractive index of the front member 102 is 1.40, and the refractive index of air is 1.

[0118] In comparative structure 1, the refractive index of the low refractive index layer 104 is 1.48, the refractive index of the high refractive index layer 105 is 1.65, the refractive index of the substrate 101 is 1.35, the refractive index of the front member 102 is 1.40, and the refractive index of air is 1.

[0119] In Comparative Structure 2, the refractive index of the low refractive index layer 104 is 1.48, the refractive index of the high refractive index layer 105 is 1.65, the refractive index of the substrate 101 is 1.87, the refractive index of the front member 102 is 1.40, and the refractive index of air is 1.

[0120] [Table 1]

[0121] Optical film of embodiment Comparative structure 1 optical film Comparative Structure 2 Optical Film Refractive index of air 1.00 1.00 1.00 Refractive index of the front element 1.40 1.40 1.40 Refractive index of substrate 1.49 1.35 1.87 Refractive index of the high refractive index layer 1.65 1.65 1.65 Refractive index of the low refractive index layer 1.48 1.48 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.6％ 95.9％ 94.6％ Energy transmittance of p-wave at an incident angle of 20 degrees 97.9％ 97.4％ 96.2％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.2％ 93.1％ 92.7％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 96.6％ 95.9％ 94.6％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.0％ 94.2％ 92.6％ Energy transmittance of s-wave at an incident angle of 40 degrees 69.8％ 68.4％ 66.5％

[0122] As shown in Table 1, the optical film 100 of the embodiment has higher energy transmittance Tp of p-wave light and higher energy transmittance Ts of s-wave light than those of comparative structures 1 and 2. In particular, in the case of s-wave light with an incident angle of 40 degrees, the energy transmittance Ts is significantly higher than those of comparative structures 1 and 2.

[0123] (Calculation Example 2)

[0124] Calculation Example 2 is different from Calculation Example 1 in that the refractive index of the front surface member of each of the embodiment and the comparative structures 1 and 2 is 1.38. Table 2 shows the calculation results of the energy transmittance of Calculation Example 2.

[0125] [Table 2]

[0126] Optical film of embodiment Comparative structure 1 optical film Comparative Structure 2 Optical Film Refractive index of air 1.00 1.00 1.00 Refractive index of the front element 1.38 1.38 1.38 Refractive index of substrate 1.49 1.35 1.87 Refractive index of the high refractive index layer 1.65 1.65 1.65 Refractive index of the low refractive index layer 1.48 1.48 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.8％ 96.2％ 94.6％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.0％ 97.5％ 96.2％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.1％ 93.1％ 92.7％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 96.8％ 96.2％ 94.6％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.3％ 94.6％ 92.7％ Energy transmittance of s-wave at an incident angle of 40 degrees 70.7％ 69.4％ 67.1％

[0127] As shown in Table 2, in the optical film 100 of the embodiment, the energy transmittance Tp of the p-wave light and the energy transmittance Ts of the s-wave light are both higher than those of the comparative structures 1 and 2.

[0128] (Calculation Example 3)

[0129] Calculation Example 3 is different from Calculation Example 1 in that the refractive index of the front surface member of each of the embodiment and the comparative structures 1 and 2 is 1.36. Table 3 shows the calculation results of the energy transmittance of Calculation Example 3.

[0130] [Table 3]

[0131] Optical film of embodiment Comparative structure 1 optical film Comparative Structure 2 Optical Film Refractive index of air 1.00 1.00 1.00 Refractive index of the front element 1.36 1.36 1.36 Refractive index of substrate 1.49 1.35 1.87 Refractive index of the high refractive index layer 1.65 1.65 1.65 Refractive index of the low refractive index layer 1.48 1.48 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.9％ 96.4％ 94.6％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.1％ 97.7％ 96.2％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.1％ 93.1％ 92.6％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 96.9％ 96.4％ 94.6％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.5％ 94.9％ 92.7％ Energy transmittance of s-wave at an incident angle of 40 degrees 71.6％ 70.5％ 67.6％

[0132] As shown in Table 3, in the optical film 100 of the embodiment, the energy transmittance Tp of p-wave light and the energy transmittance Ts of s-wave light are both higher than those of the comparative structures 1 and 2.

[0133] (Calculation Example 4)

[0134] Calculation Example 4 is different from Calculation Example 1 in that the refractive index of the front surface member of each of the embodiment and the comparative structures 1 and 2 is 1.34. Table 4 shows the calculation results of the energy transmittance of Calculation Example 4.

[0135] [Table 4]

[0136] Optical film of embodiment Comparative structure 1 optical film Comparative Structure 2 Optical Film Refractive index of air 1.00 1.00 1.00 Refractive index of the front element 1.34 1.34 1.34 Refractive index of substrate 1.49 1.35 1.87 Refractive index of the high refractive index layer 1.65 1.65 1.65 Refractive index of the low refractive index layer 1.48 1.48 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 97.1％ 96.6％ 94.6％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.2％ 97.8％ 96.1％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.1％ 93.1％ 92.6％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 97.1％ 96.6％ 94.6％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.7％ 95.2％ 92.7％ Energy transmittance of s-wave at an incident angle of 40 degrees 72.5％ 71.6％ 68.1％

[0137] As shown in Table 4, in the optical film 100 of the embodiment, the energy transmittance Tp of the p-wave light and the energy transmittance Ts of the s-wave light are higher than those of the comparative structures 1 and 2.

[0138] (Calculation Example 5)

[0139] Calculation Example 5 is different from Calculation Example 1 in that the refractive index of the front surface member of each of the embodiment and the comparative structures 1 and 2 is 1.32. Table 5 shows the calculation results of the energy transmittance of Calculation Example 5.

[0140] [Table 5]

[0141] Optical film of embodiment Comparative structure 1 optical film Comparative Structure 2 Optical Film Refractive index of air 1.00 1.00 1.00 Refractive index of the front element 1.32 1.32 1.32 Refractive index of substrate 1.49 1.35 1.87 Refractive index of the high refractive index layer 1.65 1.65 1.65 Refractive index of the low refractive index layer 1.48 1.48 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 97.2％ 96.8％ 94.5％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.2％ 97.9％ 96.1％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.1％ 93.1％ 92.6％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 97.2％ 96.8％ 94.5％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.9％ 95.5％ 92.7％ Energy transmittance of s-wave at an incident angle of 40 degrees 73.4％ 72.6％ 68.6％

[0142] As shown in Table 5, in the optical film 100 of the embodiment, the energy transmittance Tp of the p-wave light and the energy transmittance Ts of the s-wave light are higher than those of the comparative structures 1 and 2.

[0143] (Calculation Example 6)

[0144] Calculation Example 6 is different from Calculation Example 1 in that the refractive index of the front surface member of each of the embodiment and Comparative Structures 1 and 2 is 1.30. Table 6 shows the calculation results of the energy transmittance of Calculation Example 6.

[0145] [Table 6]

[0146] Optical film of embodiment Comparative structure 1 optical film Comparative Structure 2 Optical Film Refractive index of air 1.00 1.00 1.00 Refractive index of the front element 1.30 1.30 1.30 Refractive index of substrate 1.49 1.35 1.87 Refractive index of the high refractive index layer 1.65 1.65 1.65 Refractive index of the low refractive index layer 1.48 1.48 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 97.3％ 97.0％ 94.5％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.3％ 98.0％ 96.0％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.2％ 93.1％ 92.7％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 97.3％ 97.0％ 94.5％ Energy transmittance of s-wave at an incident angle of 20 degrees 96.1％ 95.7％ 92.6％ Energy transmittance of s-wave at an incident angle of 40 degrees 74.3％ 73.7％ 69.1％

[0147] As shown in Table 6, in the optical film 100 of the embodiment, the energy transmittance Tp of the p-wave light and the energy transmittance Ts of the s-wave light are higher than those of the comparative structures 1 and 2.

[0148] (Calculation Example 7)

[0149] Calculation Example 7 is different from Calculation Example 1 in that the refractive index of the front surface member of each of the embodiment and Comparative Structures 1 and 2 is 1.28. Table 7 shows the calculation results of the energy transmittance of Calculation Example 7.

[0150] [Table 7]

[0151] Optical film of embodiment Comparative structure 1 optical film Comparative Structure 2 Optical Film Refractive index of air 1.00 1.00 1.00 Refractive index of the front element 1.28 1.28 1.28 Refractive index of substrate 1.49 1.35 1.87 Refractive index of the high refractive index layer 1.65 1.65 1.65 Refractive index of the low refractive index layer 1.48 1.48 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 97.4％ 97.2％ 94.4％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.3％ 98.1％ 95.9％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.2％ 93.2％ 92.8％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 97.4％ 97.2％ 94.4％ Energy transmittance of s-wave at an incident angle of 20 degrees 96.2％ 95.9％ 92.6％ Energy transmittance of s-wave at an incident angle of 40 degrees 75.1％ 74.8％ 69.5％

[0152] As shown in Table 7, in the optical film 100 of the embodiment, the energy transmittance Tp of the p-wave light and the energy transmittance Ts of the s-wave light are higher than those of the comparative structures 1 and 2.

[0153] (Calculation Example 8)

[0154] Calculation Example 8 is different from Calculation Example 1 in that the refractive index of the front surface member of each of the embodiment and Comparative Structures 1 and 2 is 1.42. Table 8 shows the calculation results of the energy transmittance of Calculation Example 8.

[0155] [Table 8]

[0156] Optical film of embodiment Comparative structure 1 optical film Comparative Structure 2 Optical Film Refractive index of air 1.00 1.00 1.00 Refractive index of the front element 1.42 1.42 1.42 Refractive index of substrate 1.49 1.35 1.87 Refractive index of the high refractive index layer 1.65 1.65 1.65 Refractive index of the low refractive index layer 1.48 1.48 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.4％ 95.7％ 94.5％ Energy transmittance of p-wave at an incident angle of 20 degrees 97.7％ 97.2％ 96.2％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.2％ 93.2％ 92.8％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 96.4％ 95.7％ 94.5％ Energy transmittance of s-wave at an incident angle of 20 degrees 94.8％ 93.9％ 92.5％ Energy transmittance of s-wave at an incident angle of 40 degrees 68.9％ 67.3％ 65.9％

[0157] As shown in Table 8, in the optical film 100 of the embodiment, the energy transmittance Tp of the p-wave light and the energy transmittance Ts of the s-wave light are higher than those of the comparative structures 1 and 2.

[0158] (Calculation Example 9)

[0159] Calculation Example 9 is different from Calculation Example 1 in that the refractive index of the front surface member of each of the embodiment and the comparative structures 1 and 2 is 1.44. Table 9 shows the calculation results of the energy transmittance of Calculation Example 9.

[0160] [Table 9]

[0161] Optical film of embodiment Comparative structure 1 optical film Comparative Structure 2 Optical Film Refractive index of air 1.00 1.00 1.00 Refractive index of the front element 1.44 1.44 1.44 Refractive index of substrate 1.49 1.35 1.67 Refractive index of the high refractive index layer 1.65 1.65 1.65 Refractive index of the low refractive index layer 1.48 1.48 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.2％ 95.4％ 94.5％ Energy transmittance of p-wave at an incident angle of 20 degrees 97.6％ 97.0％ 96.2％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.3％ 93.3％ 92.9％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 96.2％ 95.4％ 94.5％ Energy transmittance of s-wave at an incident angle of 20 degrees 94.5％ 93.5％ 92.4％ Energy transmittance of s-wave at an incident angle of 40 degrees 68.0％ 66.3％ 65.4％

[0162] As shown in Table 9, in the optical film 100 of the embodiment, the energy transmittance Tp of the p-wave light and the energy transmittance Ts of the s-wave light are higher than those of the comparative structures 1 and 2.

[0163] (Calculation Example 10)

[0164] Calculation Example 10 is different from Calculation Example 1 in that the refractive index of the substrate 101 of the embodiment is 1.47. Table 10 shows the calculation results of the energy transmittance of Calculation Example 10.

[0165] [Table 10]

[0166] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.40 Refractive index of substrate 1.47 Refractive index of the high refractive index layer 1.65 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.56％ Energy transmittance of p-wave at an incident angle of 20 degrees 97.82％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.17％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 96.56％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.00％ Energy transmittance of s-wave at an incident angle of 40 degrees 69.75％

[0167] (Calculation Example 11)

[0168] Calculation Example 11 is different from Calculation Example 1 in that the refractive index of the substrate 101 of the embodiment is 1.51. Table 11 shows the calculation results of the energy transmittance of Calculation Example 11.

[0169] [Table 11]

[0170] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.40 Refractive index of substrate 1.51 Refractive index of the high refractive index layer 1.65 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.61％ Energy transmittance of p-wave at an incident angle of 20 degrees 97.87％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.19％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 96.61％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.06％ Energy transmittance of s-wave at an incident angle of 40 degrees 69.83％

[0171] (Calculation Example 12)

[0172] Calculation Example 12 is different from Calculation Example 1 in that the refractive index of the substrate 101 of the embodiment is 1.53. Table 12 shows the calculation results of the energy transmittance of Calculation Example 12.

[0173] [Table 12]

[0174] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.40 Refractive index of substrate 1.53 Refractive index of the high refractive index layer 1.65 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.61％ Energy transmittance of p-wave at an incident angle of 20 degrees 97.87％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.19％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 96.61％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.06％ Energy transmittance of s-wave at an incident angle of 40 degrees 69.82％

[0175] (Calculation Example 13)

[0176] Calculation Example 13 is different from Calculation Example 1 in that the refractive index of the substrate 101 of the embodiment is 1.55. Table 13 shows the calculation results of the energy transmittance of Calculation Example 13.

[0177] [Table 13]

[0178] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.40 Refractive index of substrate 1.55 Refractive index of the high refractive index layer 1.65 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.59％ Energy transmittance of p-wave at an incident angle of 20 degrees 97.86％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.19％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 96.59％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.04％ Energy transmittance of s-wave at an incident angle of 40 degrees 69.78％

[0179] (Calculation Example 14)

[0180] Calculation Example 14 is different from Calculation Example 1 in that the refractive index of the substrate 101 of the embodiment is 1.41. Table 14 shows the calculation results of the energy transmittance of Calculation Example 14.

[0181] [Table 14]

[0182] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.40 Refractive index of substrate 1.41 Refractive index of the high refractive index layer 1.65 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.34％ Energy transmittance of p-wave at an incident angle of 20 degrees 97.66％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.16％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 93.16％ Energy transmittance of s-wave at an incident angle of 20 degrees 94.73％ Energy transmittance of s-wave at an incident angle of 40 degrees 69.31％

[0183] (Calculation Example 15)

[0184] Calculation Example 15 is different from Calculation Example 1 in that the refractive index of the substrate 101 of the embodiment is 1.59. Table 15 shows the calculation results of the energy transmittance of Calculation Example 15.

[0185] [Table 15]

[0186] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.40 Refractive index of substrate 1.59 Refractive index of the high refractive index layer 1.65 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 96.51％ Energy transmittance of p-wave at an incident angle of 20 degrees 97.80％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.18％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 93.18％ Energy transmittance of s-wave at an incident angle of 20 degrees 94.94％ Energy transmittance of s-wave at an incident angle of 40 degrees 69.62％

[0187] (Calculation Example 16)

[0188] Calculation Example 16 is different from Calculation Example 1 in that the refractive index of the front member 102 of the embodiment is 1.37, the refractive index of the substrate 101 is 1.38, and the refractive index of the high refractive index layer 105 is 1.58. Table 16 shows the calculation results of the energy transmittance of Calculation Example 16.

[0189] [Table 16]

[0190] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.37 Refractive index of substrate 1.38 Refractive index of the high refractive index layer 1.58 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 97.01％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.15％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.17％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 97.01％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.61％ Energy transmittance of s-wave at an incident angle of 40 degrees 71.40％

[0191] (Calculation Example 17)

[0192] Calculation Example 17 is different from Calculation Example 16 in that the refractive index of the substrate 101 of the embodiment is 1.43. Table 17 shows the calculation results of the energy transmittance of Calculation Example 17.

[0193] [Table 17]

[0194] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.37 Refractive index of substrate 1.43 Refractive index of the high refractive index layer 1.58 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 97.17％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.27％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.18％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 97.17％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.81％ Energy transmittance of s-wave at an incident angle of 40 degrees 71.75％

[0195] (Calculation Example 18)

[0196] Calculation Example 18 is different from Calculation Example 16 in that the refractive index of the substrate 101 of the embodiment is 1.49. Table 18 shows the calculation results of the energy transmittance of Calculation Example 18.

[0197] [Table 18]

[0198] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.37 Refractive index of substrate 1.49 Refractive index of the high refractive index layer 1.58 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 97.20％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.30％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.19％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 97.20％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.85％ Energy transmittance of s-wave at an incident angle of 40 degrees 71.79％

[0199] (Calculation Example 19)

[0200] Calculation Example 19 is different from Calculation Example 16 in that the refractive index of the substrate 101 of the embodiment is 1.51. Table 19 shows the calculation results of the energy transmittance of Calculation Example 19.

[0201] [Table 19]

[0202] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.37 Refractive index of substrate 1.51 Refractive index of the high refractive index layer 1.58 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 97.18％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.28％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.19％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 97.18％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.81％ Energy transmittance of s-wave at an incident angle of 40 degrees 71.73％

[0203] (Calculation Example 20)

[0204] Calculation Example 20 is different from Calculation Example 16 in that the refractive index of the substrate 101 of the embodiment is 1.57. Table 20 shows the calculation results of the energy transmittance of Calculation Example 20.

[0205] [Table 20]

[0206] Optical film of embodiment Refractive index of air 1.00 Refractive index of the front element 1.37 Refractive index of substrate 1.57 Refractive index of the high refractive index layer 1.58 Refractive index of the low refractive index layer 1.48 Energy transmittance of p-wave at an incident angle of 0.01 degrees 97.01％ Energy transmittance of p-wave at an incident angle of 20 degrees 98.15％ Energy transmittance of p-wave at an incident angle of 40 degrees 93.17％ Energy transmittance of s-wave at an incident angle of 0.01 degrees 97.01％ Energy transmittance of s-wave at an incident angle of 20 degrees 95.60％ Energy transmittance of s-wave at an incident angle of 40 degrees 71.36％

[0207] As can be seen from calculation examples 1-9, in the optical film 100 of the embodiment, the energy transmittance Tp of the D-wave light and the energy transmittance Ts of the s-wave light are both higher than those of the comparative structures 1 and 2. In particular, in the light on the high-angle side (s-wave with an incident angle of 40 degrees), the energy transmittance Ts is greatly improved compared with the comparative structures 1 and 2. That is. Based on this result, it can be said that in the optical film 100 of the embodiment, compared with the comparative structures 1 and 2, the incident light with a particularly large incident angle can be emitted more efficiently, and the display characteristics are improved.

[0208] Here, Figure 5 1 is a graph illustrating a relationship between the refractive index of the front member 102 provided in the optical film 100 of the display device 10 and the energy transmittance of light passing through the optical film 100. Figure 5 In the figure, the relationship between the refractive index of the front element 102 and the energy transmittance of the s-wave light incident from the low refractive index layer 104 to the high refractive index layer 105 at an incident angle of 40 degrees is determined based on the results of calculation examples 1 to 9. The horizontal axis represents the refractive index of the front element 102, and the vertical axis represents the energy transmittance of the s-wave light.

[0209] observe Figure 5 It can be seen that the smaller the refractive index of the front member 102 is, the more the energy transmittance of the s-wave light increases. The energy transmittance of the s-wave light in Calculation Example 1-9 exceeds 70% when the refractive index of the front member 102 is 1.40 or less. Based on this result, it can be considered that the refractive index of the front member 102 is preferably 1.40 or less.

[0210] in addition, Fig. 6A 1 is a graph illustrating a relationship between the refractive index of the substrate 101 provided in the optical film 100 of the display device 10 and the energy transmittance of light transmitted through the optical film 100. Fig. 6A In the figure, the relationship between the refractive index of the substrate 101 and the energy transmittance of the s-wave light incident from the low refractive index layer 104 to the high refractive index layer 105 at an incident angle of 40 degrees is determined based on the results of calculation examples 1 and 10 to 15. The horizontal axis represents the refractive index of the substrate 101, and the vertical axis represents the energy transmittance of the s-wave light.

[0211] observe Fig. 6A , a peak of the energy transmittance Ts of the s-wave light with an incident angle of 40 degrees occurs around the position where the refractive index of the substrate 101 is 1.51. Furthermore, considering that the tendency is a quadratic function, it can be said that when the refractive index of the substrate 101 is 1.47 to 1.55, the energy transmittance Ts of the light becomes significantly higher than in other cases.

[0212] Specifically, it is as follows.

[0213] Calculation Example 10: When the refractive index of the substrate 101 is 1.47, the difference between the refractive index difference between the high refractive index layer 105 and the substrate 101 (1.65-1.47) and the refractive index difference between the substrate 101 and the front member 102 (1.47-1.40) is 0.11. At this time, the energy transmittance Ts of the s-wave light with an incident angle of 40 degrees is 69.75%.

[0214] Calculation Example 11: When the refractive index of the substrate 101 is 1.51, the difference between the refractive index difference between the high refractive index layer 105 and the substrate 101 (1.65-1.51) and the refractive index difference between the substrate 101 and the front member 102 (1.51-1.40) is 0.03. At this time, the energy transmittance Ts of the s-wave light with an incident angle of 40 degrees is 69.83%.

[0215] Calculation Example 12: When the refractive index of the substrate 101 is 1.53, the difference between the refractive index difference between the high refractive index layer 105 and the substrate 101 (1.65-1.53) and the refractive index difference between the substrate 101 and the front member 102 (1.53-1.40) is 0.01. At this time, the energy transmittance Ts of the s-wave light with an incident angle of 40 degrees is 69.82%.

[0216] Calculation Example 13: When the refractive index of the substrate 101 is 1.55, the difference between the refractive index difference between the high refractive index layer 105 and the substrate 101 (1.65-1.55) and the refractive index difference between the substrate 101 and the front member 102 (1.55-1.40) is 0.05. At this time, the energy transmittance Ts of the s-wave light with an incident angle of 40 degrees is 69.78%.

[0217] If the above is considered, it can be said that the smaller the difference between the refractive index difference between the high refractive index layer 105 and the substrate 101 and the difference between the refractive index difference between the substrate 101 and the front element 102, the higher the energy efficiency. From such a result, it can be said that when the refractive indexes of the high refractive index layer 105, the substrate 101 and the front element 102 are successively reduced, it is preferred to change the refractive indexes of the high refractive index layer 105, the substrate 101 and the front element 102 in the same proportion or smoothly.

[0218] However, regarding Calculation Example 11, the energy transmittance Ts of the s-wave light with an incident angle of 40 degrees is higher than that of Calculation Example 12. This is considered to be because the refractive index of the substrate 101 of Calculation Example 11 is smaller than the refractive index of the substrate 101 of Calculation Example 12. That is, from this result, it can be said that if the refractive indices of the substrate 101 and the high refractive index layer 105 are respectively reduced, and the refractive indices of the high refractive index layer 105, the substrate 101, and the front member 102 are changed in the same proportion or smoothly, the light extraction efficiency will be more effectively improved.

[0219] exist Figure 6B In the above, the relationship between the refractive index of the substrate 101 and the energy transmittance of the s-wave light incident from the low refractive index layer 104 to the high refractive index layer 105 at an incident angle of 40 degrees is determined based on the results of calculation examples 16 to 20. The horizontal axis represents the refractive index of the substrate 101, and the vertical axis represents the energy transmittance of the s-wave light.

[0220] according to Figure 6B The results can also be said that, when the refractive indices of the high refractive index layer 105, the substrate 101 and the front member 102 are successively reduced, it is preferred to make the refractive indices of the high refractive index layer 105, the substrate 101 and the front member 102 change at the same ratio or smoothly. Furthermore, with regard to calculation examples 16 to 20, the refractive index of the front member 102 and the refractive index of the high refractive index layer 105 are smaller than those of calculation examples 10 to 15. Moreover, the energy transmittance Ts of the s-wave light of calculation examples 16 to 20 is larger than that of calculation examples 10 to 15 as a whole. Based on this result, it can be said that if the refractive indices of the front member 102, the substrate 101 and the high refractive index layer 105 are respectively reduced, and the refractive indices of the high refractive index layer 105, the substrate 101 and the front member 102 are respectively changed at the same ratio or smoothly, the light extraction efficiency will be more effectively improved.

[0221] In the optical film 100 of the present embodiment described above, in the optical functional layer 103, the interface of the low refractive index layer 104 and the high refractive index layer 105 forms a concavo-convex shape 120. Thus, it is possible to reflect, refract and transmit the light used for image formation from the liquid crystal panel 15 at the interface of the low refractive index layer 104 and the high refractive index layer 105, so that the light is emitted to a wider angle range, and the display quality of the image within the viewing angle can be improved. In addition, the refractive index of the high refractive index layer 105, the substrate 101 and the front member 102 respectively becomes smaller in sequence. Thus, it is possible to efficiently extract light. Therefore, it is possible to improve the display quality of the image within the viewing angle while fully suppressing the energy loss of the light forming the image.

[0222] <<Second embodiment>>

[0223] Figure 7 1 is a diagram schematically showing the structure of a display device 10-2 including an optical film 100-2 according to the second embodiment. Figure 7 As shown, in this embodiment, the positions of the low refractive index layer 104 and the high refractive index layer 105 are opposite to those in the first embodiment. That is, the optical functional layer 103 is arranged on the display device 10-2 in such a manner that the high refractive index layer 105 and the display surface A of the liquid crystal panel 15 face each other. Moreover, in this embodiment, the refractive indexes of the high refractive index layer 105, the low refractive index layer 104, the substrate 101 and the front member 102 are successively reduced.

[0224] In such an embodiment, the effect of improving the display quality within the viewing angle is different from that of the first embodiment, but the light extraction efficiency is more advantageous than that of the first embodiment.

[0225] <<Third embodiment>>

[0226] Figure 8 This is a diagram schematically showing the structure of a display device 10 - 3 including an optical film 100 - 3 according to the third embodiment. Figure 8 The display device 10-3 shown is composed of an organic LED (Organic Light Emitting Diode) panel 215, a circular polarizing plate 220, a touch panel 230, a cover glass 240, and an optical film 100-3 stacked in sequence. As an example, the display device 10-3 of this embodiment is configured as a smart phone, but it can also be a tablet terminal, a television, a computer display, a car navigation system, etc.

[0227] The display surface (surface) of the organic LED panel 215 is bonded to the back of the circular polarizer 220 via the first adhesive layer 251. The front of the circular polarizer 220 is bonded to the back of the touch panel 230 via the second adhesive layer 252. The front of the touch panel 230 is bonded to the back of the cover glass 240 via the third adhesive layer 253. Each adhesive layer 251 to 253 is a so-called OCA (Optical Clear Adhesive), which has a high light transmittance. The optical film 100-3 is arranged on the front of the cover glass 240. In this example, the optical film 100-3 and the cover glass 240 are not bonded via an adhesive layer, but they may be bonded via an adhesive layer.

[0228] In such an embodiment, the refractive indexes of the high refractive index layer 105, the substrate 101, and the front member 102 are also successively reduced, thereby improving the efficiency of light extraction from the organic LED panel 215.

[0229] <<Fourth embodiment>>

[0230] Next, refer to Figures 9 to 12 , an optical film 400 of a fourth embodiment will be described. The optical film 400 of the fourth embodiment may be applied to the display device 10 instead of the optical films of the first to third embodiments described above, or the features of the optical film 400 of the fourth embodiment described below may be combined with the optical films of the first to third embodiments described above and applied to the display device 10. In the following description, an example in which the optical film 400 of the fourth embodiment is applied instead of the optical film of the first embodiment will be described.

[0231] Fig. 9 4 is a perspective view schematically showing an optical film 400 according to a fourth embodiment. Fig.10 It is along Fig. 9 The optical film 400 is a cross-sectional view of the optical film 400 along the XX line. The optical film 400 is arranged facing the display surface 15A of the liquid crystal panel 15, and plays an optical role in the image light emitted from the display surface 15A to form an image. The optical film 400 is bonded to the liquid crystal panel 15 via a bonding layer not shown. Fig. 9 As shown, the optical film 400 is formed into a quadrilateral shape in a plan view, and is formed into a rectangular parallelepiped shape with a side in the thickness direction smaller than other sides as a whole.

[0232] exist Fig. 9 and Fig.10In the example shown, the optical film 400 includes: a substrate 401; an optical functional layer 403 provided on one side of the substrate 401; a second substrate 409 provided on the side of the optical functional layer 403 opposite to the side on which the substrate 401 is provided; and a front member 402 provided on the side of the substrate 401 opposite to the side on which the optical functional layer 403 is provided. That is, the second substrate 409, the optical functional layer 403, the substrate 401, and the front member 402 are stacked in order from the side close to the display surface 15A of the liquid crystal panel 15. The side of the optical film 400 on which the optical functional layer 403 is provided becomes the side facing the display surface 15A of the liquid crystal panel 15. Therefore, the front member 402 of the optical film 400 constitutes the front surface of the display device 10.

[0233] The substrate 401 and the second substrate 409 are supporting substrates that appropriately support the optical functional layer 403. More specifically, the substrate 401 supports the second layer 405 described later of the optical functional layer 403, and the second substrate 409 supports the third layer 406 described later of the optical functional layer 403. The substrate 401 and the second substrate 409 are transparent, and are made of, for example, triacetyl cellulose, polyethylene terephthalate, polyolefin, polycarbonate, polyacrylate, polyamide, glass, etc. Considering transparency, appropriate support for the optical functional layer 403, etc., the substrate 401 and the second substrate 409 preferably have a thickness of 5 μm or more and 120 μm or less, more preferably have a thickness of 20 μm or more and 90 μm or less, and further preferably have a thickness of 50 μm or more and 85 μm or less. In addition, the refractive index of the substrate 401 and the second substrate 409 is preferably in the range of 1.38 or more and 1.57 or less, and more preferably 1.47 or more and 1.54 or less. It should be noted that the second substrate 409 may also be omitted by being removed or the like in the manufacturing process of the optical film 400. Alternatively, the second substrate 409 may also be formed of the same material as the third layer 406 of the optical functional layer 403 described later, and formed integrally with the third layer 406.

[0234] It should be noted that "transparent" means having a degree of transparency that allows one side of the substrate to be seen through the other side, for example, a total light transmittance of 87% or more (preferably 90% or more). The total light transmittance can be measured using a measuring device in accordance with JIS K 7361-1:1997 (for example, "HM150" manufactured by Murakami Color Research Laboratory).

[0235] The front member 402 constitutes the front side of the display device 10, and is formed as a functional layer that performs a specific function. The function performed by the front member 402 includes, for example, an anti-reflection function. According to the front member 402 having an anti-reflection function, it is possible to suppress the visual recognizability of the image displayed on the display device 10 from being impaired due to surface reflection of light from the outside. In addition, the refractive index of the front member 402 is less than 1.40. However, the front member 402 is not limited to the anti-reflection function, and may also have a hard coating function, an anti-fouling function, an anti-static function, etc.

[0236] The structure and material of the front member 402 are not particularly limited, and as its structure, a low-refractive index single-layer structure, a two-layer or three-layer dielectric multilayer structure, and a hollow particle or porous structure can be cited. Such a front member 402 can, for example, be set to the same structure as the front member 102 of the first embodiment described above.

[0237] The optical functional layer 403 includes a second layer 405, a first layer 404 stacked on the second layer 405, and a third layer 406 stacked on the first layer 404 on the opposite side of the second layer 405. The second layer 405 includes a portion arranged in the first direction D1 and extending in the second direction D2 intersecting the first direction D1. In the example shown in the figure, the first direction D1 and the second direction D2 are orthogonal to each other. The third layer 406 includes a portion arranged in the first direction D1 and extending in the second direction D2. The first layer 404 includes: a portion extending in the second direction D2 and alternately arranged with the second layer 405 along the first direction D1; and a portion extending in the second direction D2 and alternately arranged with the third layer 406 along the first direction D1.

[0238] The second layer 405 is formed on one side of the substrate 401 in the optical film 400, and the third layer 406 is formed on the side facing the display surface 15A of the liquid crystal panel 15 in the optical film 400. The first layer 404 is located between the second layer 405 and the third layer 406. The refractive index of the second layer 405 is different from that of the first layer 404. The refractive index of the first layer 404 is different from that of the third layer 406. Therefore, the first interface 420 between the second layer 405 and the first layer 404 and the second interface 430 between the first layer 404 and the third layer 406 become optical interfaces. In addition, the first interface 420 and the second interface 430 are concave-convex shapes. Therefore, the first interface 420 and the second interface 430 are used as lenses. The first interface 420 includes a flat surface 420A parallel to the display surface 15A and an inclined surface 420S not parallel to the display surface 15A. The optical film 400 can easily emit image light in a direction inclined in the first direction D1 with respect to the front direction (normal direction) of the display device 10 due to the optical effects at the concavo-convex first interface 420 and the second interface 430 .

[0239] like Fig.10 As shown, the cross-sectional shape of the second layer 405 is a substantially trapezoidal shape with a long base on the substrate 401 side and a short base on the side opposite to the substrate 401. That is, the cross-sectional shape of the second layer 405 is such that the width along the first direction D1 increases as it approaches the substrate 401. Here, "the width along the first direction D1 increases as it approaches the substrate 401" not only means that the width along the first direction D1 continuously changes according to the distance from the substrate 401, but also means that it does not include a portion where the width along the first direction D1 decreases as it approaches the substrate 401, and therefore, it also includes the case where the width along the first direction D1 changes in stages according to the distance from the substrate 401. However, it is preferred that the cross-sectional shape of the second layer 405 continuously changes according to the distance from the substrate 401.

[0240] In addition, the cross-sectional shape of the second layer 405 may be such that the legs of the trapezoidal shape are not straight lines but curves. That is, the side surface of the second layer 405 may also be a curved surface. By changing the cross-sectional shape of the second layer 405, the shape of the inclined surface 420S of the optical first interface 420 between the second layer 405 and the first layer 404 is changed, and the desired optical characteristics can be exerted in the shape of the first interface 420.

[0241] The second layer 405 is transparent and can be formed by, for example, placing an ultraviolet curing resin such as urethane acrylate on the substrate 401 and curing the resin by irradiating the substrate with ultraviolet rays.

[0242] like Fig. 9 and Fig.10 As shown in FIG. 1 , the first layer 404 is provided so as to fill the space between the adjacent portions of the second layer 405 extending in the first direction D1 and the adjacent portions of the third layer 406 extending in the first direction D1. In other words, the first layer 404 is provided so as to fill the space between the second layer 405 and the third layer 406. The first layer 404 is, for example, a bonding layer that bonds the second layer 405 and the third layer 406. In addition, the first layer 404 is transparent. Such a first layer 404 can be formed of, for example, an acrylic ultraviolet curing resin.

[0243] like Fig.10As shown, the cross-sectional shape of the third layer 406 is such that the width along the first direction D1 decreases as it approaches the first layer 404. In the example shown in the figure, the cross-sectional shape of the third layer 406 is a semi-elliptical shape. Here, "the width along the first direction D1 decreases as it approaches the first layer 404" not only means that the width along the first direction D1 continuously changes according to the distance from the first layer 404, but also means that it does not include the part where the width along the first direction D1 increases as it approaches the first layer 404, and therefore, it also includes the case where the width along the first direction D1 changes in stages according to the distance from the first layer 404. However, it is preferred that the cross-sectional shape of the third layer 406 continuously changes according to the distance from the first layer 404.

[0244] In addition, the cross-sectional shape of the third layer 406 may include not only the curve shown in the figure but also a straight line portion. According to the cross-sectional shape of the third layer 406, the shape of the optical second interface 430 between the first layer 404 and the third layer 406 changes, so that the desired optical characteristics can be exerted in the shape of the second interface 430.

[0245] The third layer 406 is transparent and can be formed by, for example, placing an ultraviolet curing resin such as urethane acrylate on the second substrate 409 and curing the resin by irradiating the second substrate 409 with ultraviolet rays.

[0246] In the present embodiment, the refractive index of the first layer 404 is smaller than the refractive index of the second layer 405 and the refractive index of the third layer 406. Therefore, the difference between the refractive index of the second layer 405 and the refractive index of the first layer 404, and the difference between the refractive index of the first layer 404 and the refractive index of the third layer 406 can be increased. If the refractive index difference becomes larger, it is easy to exert the optical effect at the interface. Specifically, the difference between the refractive index of the second layer 405 and the refractive index of the first layer 404, and the difference between the refractive index of the first layer 404 and the refractive index of the third layer 406 are preferably 0.05 or more and 0.25 or less. In addition, in the present embodiment, the refractive index of the second layer 405 is, for example, 1.6 or more, the refractive index of the first layer 404 is, for example, 1.49 or less, and the refractive index of the third layer 406 is, for example, 1.6 or more. The comparison of the refractive index at the interface can be confirmed, for example, by the refraction direction of light incident on the interface or the total reflection condition. In addition, the specific value of the refractive index can be measured by, for example, using an Abbe refractometer (for example, RX-7000α manufactured by ATAGO Corporation).

[0247] In addition, the pitch of the concavoconvexities of the concavoconvex shape of the first interface 420 is smaller than the pitch of the pixels of the liquid crystal panel 15. In particular, the ratio of the pitch of the pixels of the liquid crystal panel 15 to the pitch of the concavoconvexities of the concavoconvex shape of the first interface 420 is preferably less than 1 / 5, and more preferably less than 1 / 10. Moreover, the pitch of the concavoconvexities of the concavoconvex shape of the first interface 420 is larger than the pitch of the concavoconvexities of the concavoconvex shape of the second interface 430. Specifically, the pitch of the concavoconvexities of the concavoconvex shape of the first interface 420 is preferably more than 3 times the pitch of the concavoconvexities of the concavoconvex shape of the second interface 430. Specifically, the pitch of the concavoconvexities of the concavoconvex shape of the first interface 420 is, for example, less than 35 μm. In addition, the pitch of the concavoconvexities of the concavoconvex shape of the second interface 430 is, for example, less than 12 μm.

[0248] Next, the operation of the optical film 400 according to the present embodiment and the display device 10 including the optical film 400 will be described.

[0249] Image light emitted from the display surface 15A of the liquid crystal panel 15 is incident on the optical function layer 403 of the optical film 400. Fig.11 As shown, the image light incident on the optical functional layer 403 first enters the third layer 406, and then is incident on the second interface 430 between the third layer 406 and the first layer 404. Among the image light incident on the second interface 430, the image light L111 traveling in the same direction as the normal direction of the incident position passes through the second interface 430 without being refracted at the second interface 430. On the other hand, among the image light incident on the second interface 430, the image light traveling in a direction different from the normal direction of the incident position (and the image light L112, L113 traveling in the front direction, and the image light L114, L115 traveling in a direction inclined relative to the front direction) is refracted in a manner in which the inclination angle relative to the front direction increases due to the refractive index difference between the first layer 404 and the third layer 406. The image lights L112 to L115 that have passed through the second interface 430 are transmitted through the first layer 404 and are incident on the first interface 420 between the first layer 404 and the second layer 405 .

[0250] The image light L111 incident on the flat surface 420A of the first interface 420 between the second layer 405 and the first layer 404 in the same direction as the normal direction of the flat surface 420A passes through the first interface 420 without being refracted at the first interface 420, and is emitted from the optical function layer 403. On the other hand, the image light L112 to L115 incident on the inclined surface 420S of the first interface 420 between the second layer 405 and the first layer 404 is refracted in a manner that further increases the inclination angle with respect to the front direction due to the refractive index difference between the second layer 405 and the first layer 404. Thereafter, part of the image light L112 and L114 is emitted from the optical function layer 403, and the other part of the image light L113 and L115 is further refracted at the first interface 420 between the second layer 405 and the first layer 404 and then emitted from the optical function layer 403. The image lights L112 to L115 travel in a direction more inclined with respect to the front direction due to refraction at the second interface 430 between the first layer 404 and the third layer 406 and refraction at the first interface 420 between the second layer 405 and the first layer 404 when passing through the optical function layer 403 .

[0251] In addition, the optical effects to which the image light is subjected at the first interface 420 and the second interface 430 include not only the refraction effect described above, but also the diffraction effect generated based on the concavo-convex shape of the first interface 420 and the concavo-convex shape of the second interface 430. That is, the image light incident on the optical functional layer 403 is diffracted by the concavo-convex shape of the first interface 420 and the concavo-convex shape of the second interface 430, and travels in a direction that is more inclined with respect to the front direction.

[0252] However, for example, in the optical film shown in Japanese Patent No. 6447654, there is only one optical interface between the low refractive index layer and the high refractive index layer. Therefore, the image light passing through the optical film is only subjected to the optical action at the interface once. That is, the image light is refracted and diffracted only once. It is difficult to expand the image light to a larger viewing angle by only one refraction and diffraction. In other words, sometimes the viewing angle cannot be fully expanded.

[0253] On the other hand, in the present embodiment, as described above, the image light emitted from the display surface 15A passes through the first interface 420 between the second layer 405 and the first layer 404 and the second interface 430 between the first layer 404 and the third layer 406, and thus passes through the two optical interfaces 420 and 430. That is, due to the refraction and diffraction at the second interface 430 between the first layer 404 and the third layer 406, and the refraction and diffraction at the first interface 420 between the second layer 405 and the first layer 404, when the image light passes through the optical functional layer 403, as shown in FIG. Fig.11As shown, there will be a tendency for the angle of the traveling direction of the image light relative to the front direction to become larger. In this way, the image light is subjected to the optical action at the interface twice, that is, the refraction and diffraction at the interface. Through the two refractions and diffractions, the inclination angle of the image light relative to the front direction becomes larger. Therefore, it is easy to emit the image light in the direction inclined from the front direction to the first direction D1. Therefore, the image light can be clearly observed even from the direction inclined relative to the first direction D1. That is, the viewing angle of the image from the display device 10 can be expanded. In this way, by refracting and diffracting the image light twice in a manner that increases the inclination angle relative to the front direction, the image light can be expanded to a larger viewing angle compared to a single refraction and diffraction.

[0254] The refractive index of the first layer 404 is smaller than the refractive index of the second layer 405 and the refractive index of the third layer 406. Therefore, the difference between the refractive index of the second layer 405 and the refractive index of the first layer 404 and the refractive index of the third layer 406 can be increased. If the refractive index difference becomes larger, it is easy to exert the optical effect at the interface. That is, at the first interface 420 and the second interface 430, light is easily refracted and diffracted at a large refraction angle. By passing the image light through such a first interface 420 and the second interface 430, the image light can be expanded to a larger viewing angle.

[0255] Moreover, the pitch of the concavoconvex of the concavoconvex shape of the first interface 420 is larger than the pitch of the concavoconvex of the concavoconvex shape of the second interface 430. That is, the pitch of the concavoconvex of the concavoconvex shape of the first interface 420 is different from the pitch of the concavoconvex of the concavoconvex shape of the second interface 430. Therefore, it is difficult to generate interference fringes caused by the interference between the concavoconvex shape of the first interface 420 and the concavoconvex shape of the second interface 430. In particular, if the pitch of the concavoconvex of the concavoconvex shape of the first interface 420 is more than 3 times the pitch of the concavoconvex of the concavoconvex shape of the second interface 430, the interference fringes are almost invisible. By suppressing the generation of interference fringes, it is possible to suppress the deterioration of the visual confirmation of the image displayed on the display device 10 due to the visual confirmation of the interference fringes.

[0256] In addition, various changes can be added to the fourth embodiment.

[0257] For example, in the above-described embodiment, in order to increase the difference between the refractive index of the second layer 405 and the refractive index of the first layer 404, and the difference between the refractive index of the first layer 404 and the refractive index of the third layer 406, the refractive index of the first layer 404 is smaller than the refractive index of the second layer 405 and the refractive index of the third layer 406. However, the refractive index of the first layer 404 may be larger than the refractive index of the second layer 405 and the refractive index of the third layer 406. In this case, the refractive index of the second layer 405 is, for example, 1.49 or less, the refractive index of the first layer 404 is, for example, 1.6 or more, and the refractive index of the third layer 406 is, for example, 1.49 or less.

[0258] In this modification, the image light travels in a direction more inclined with respect to the front direction due to refraction at the second interface 430 between the first layer 404 and the third layer 406 and refraction at the first interface 420 between the second layer 405 and the first layer 404. That is, the image light can be expanded to a larger viewing angle.

[0259] In addition, the second substrate 409 of the optical film 400 may also be a polarizing plate. In this case, the upper polarizing plate 13 in the liquid crystal panel 15 can be omitted. That is, the second substrate 409 functions as the upper polarizing plate 13 of the liquid crystal panel 15. Therefore, the second substrate 409 as a polarizing plate absorbs the linear polarization component vibrating in a direction different from the linear polarization component absorbed by the lower polarizing plate 14. According to such a structure, the bonding layer for bonding the optical film 400 to the liquid crystal panel 15 can be omitted. Therefore, the display device 10 having the optical film 400 can be easily manufactured.

[0260] Hereinafter, the optical film 400 according to the fourth embodiment will be described in more detail using examples, but the optical film 400 according to the fourth embodiment is not limited to the following examples.

[0261] For the following Examples 1 and 2 and Comparative Examples 1 and 2, the brightness was measured at various angles tilted relative to the front direction of the liquid crystal panel while a white image was displayed on the display surface of the liquid crystal panel. The brightness at each angle was divided by the brightness at an angle of 0°, that is, the brightness in the front direction, and the angular distribution of the standardized brightness was calculated.

[0262] In Examples 1, 2 and Comparative Example 2, an optical film is provided facing the display surface of the liquid crystal panel. In Examples 1 and 2, the optical film has a second layer, a first layer stacked on the second layer, and a third layer stacked on the first layer on the opposite side of the second layer. The first interface between the second layer and the first layer is concave-convex. The second interface between the first layer and the third layer is also concave-convex. In a cross section orthogonal to the extension direction of the second layer, the spacing of the concave-convex shape of the first interface is 35 μm. The length of the flat surface of the first interface on the side close to the liquid crystal panel is 10.2 μm. The length of the flat surface of the first interface on the side away from the liquid crystal panel is 17.6 μm. The length of the inclined surface of the first interface is 16.8 μm. The inclined surface of the first interface is a curved surface with a curvature radius of 61 μm. In addition, in a cross section orthogonal to the extension direction of the third layer, the second interface becomes a semi-elliptical shape. The spacing of the concave-convex shape of the second interface is 8.75 μm. The short diameter of the semi-elliptical shape of the second interface is 8.75 μm, and the long diameter is 17.5 μm. In Example 1, the refractive index of the first layer is smaller than the refractive index of the second layer and the refractive index of the third layer. Specifically, the refractive index of the second layer is 1.65, the refractive index of the first layer is 1.48, and the refractive index of the third layer is 1.65. In Example 2, the refractive index of the first layer is greater than the refractive index of the second layer and the refractive index of the third layer. Specifically, the refractive index of the second layer is 1.48, the refractive index of the first layer is 1.65, and the refractive index of the third layer is 1.48. In Comparative Example 2, the optical film has a second layer and a first layer stacked on the second layer, but unlike Examples 1 and 2, it does not have a third layer. The first interface between the second layer and the first layer is concave-convex in shape. The pitch of the concavo-convex shape of the first interface is 35 μm, the length of the flat surface of the first interface on the side close to the display device is 10.2 μm, and the length of the flat surface of the first interface on the side away from the display device is 17.6 μm. The refractive index of the second layer is greater than the refractive index of the first layer. Specifically, the refractive index of the second layer is 1.65, and the refractive index of the first layer is 1.48. In Comparative Example 1, no optical film facing the liquid crystal panel is provided.

[0263] Fig.12 The following is a graph showing the angular distribution of the normalized brightness at various angles (viewing angles) relative to the front direction in each embodiment and comparative example. Fig.12 It can be seen that the normalized brightness becomes higher at a larger viewing angle in Examples 1 and 2 than in Comparative Examples 1 and 2. This is considered to be because the angle formed by the traveling direction of light relative to the front direction becomes larger due to refraction and diffraction at the second interface between the first layer and the third layer and refraction and diffraction at the first interface between the second layer and the first layer, so it is easy to emit image light at a larger viewing angle.

[0264] <<Fifth embodiment>>

[0265] Next, we will refer to Fig.13 and Fig.16 The optical film 500 of the fifth embodiment will be described. The optical film 500 of the fifth embodiment may be applied to the display device 10 instead of the optical films of the first to third embodiments described above, or the features of the optical film 500 of the fifth embodiment described below may be combined with the optical films of the first to third embodiments described above and applied to the display device 10. In the following description, an example in which the optical film 500 of the fifth embodiment is applied instead of the optical film of the first embodiment will be described.

[0266] Fig.13 1 is a perspective view schematically showing an optical film 500 according to a fifth embodiment. Fig.14 It is along Fig.13 The optical film 500 is a cross-sectional view of the optical film 500 along the XIV-XIV line. The optical film 500 is arranged facing the display surface 15A of the liquid crystal panel 15 and plays an optical role on the image light emitted from the display surface 15A. Fig.13 As shown, the optical film 500 is formed into a quadrilateral shape in a plan view, and is formed into a rectangular parallelepiped shape in which the sides in the thickness direction are smaller than the other sides as a whole.

[0267] exist Fig.13 and Fig.14 In the example shown, the optical film 500 includes a substrate 501, an optical functional layer 503 provided on one side of the substrate 501, a coloring layer 550 disposed between the substrate 501 and the optical functional layer 503, and a front member 502 provided on the side of the substrate 501 opposite to the side provided with the optical functional layer 503. The side of the optical film 500 provided with the optical functional layer 503 becomes the side facing the display surface 15A of the liquid crystal panel 15. Therefore, the front member 502 of the optical film 500 constitutes the front surface of the display device 10.

[0268] The substrate 501 is a supporting substrate that appropriately supports the optical functional layer 503. The substrate 501 is transparent, and is made of, for example, triacetyl cellulose, polyethylene terephthalate, polyolefin, polycarbonate, polyacrylate, polyamide, glass, etc. Considering transparency or appropriate support for the optical functional layer 503, the substrate 501 preferably has a thickness of 5 μm or more and 120 μm or less, more preferably 20 μm or more and 90 μm or less, and further preferably 50 μm or more and 85 μm or less. In addition, the refractive index of the substrate 501 is preferably in the range of 1.38 or more and 1.57 or less, and more preferably 1.47 or more and 1.54 or less.

[0269] The front member 502 constitutes the front side of the display device 10, and is formed as a functional layer that performs a specific function. The function performed by the front member 502 includes, for example, an anti-reflection function. According to the front member 502 having an anti-reflection function, it is possible to suppress the situation where the visual recognizability of the image displayed on the display device 10 is impaired due to surface reflection of light from the outside. In addition, the refractive index of the front member 502 is less than 1.40. However, the front member 502 is not limited to the anti-reflection function, and may also have a hard coating function, an anti-fouling function, an anti-static function, etc.

[0270] The structure and material of the front member 502 are not particularly limited, and as its structure, a low-refractive index single-layer structure, a two-layer or three-layer dielectric multilayer structure, and a hollow particle or porous structure can be cited. Such a front member 502 can be, for example, set to the same structure as the front member 102 of the first embodiment described above.

[0271] The optical functional layer 503 includes a second layer 505 and a first layer 504 stacked on the second layer 505. The second layer 505 includes a portion arranged in the first direction D1 and extending in the second direction D2 intersecting the first direction D1. In the illustrated example, the first direction D1 and the second direction D2 are orthogonal to each other. The first layer 504 includes a portion extending in the second direction D2 and alternately arranged with the second layer 505 in the first direction D1. The second layer 505 becomes the substrate 501 side in the optical film 500, and the first layer 504 becomes the side facing the display surface 15A of the liquid crystal panel 15 in the optical film 500. The refractive index of the second layer 505 and the refractive index of the first layer 504 are different from each other. Therefore, the interface 520 between the second layer 505 and the first layer 504 becomes an optical interface. In addition, the interface 520 between the second layer 505 and the first layer 504 is concave-convex and forms a lens. The interface 520 between the second layer 505 and the first layer 504 includes a flat surface 520A parallel to the display surface 15A and an inclined surface 520S not parallel to the display surface 15A. By virtue of the optical effect at the concave-convex interface 520, in particular, by virtue of the optical effect of the inclined surface 520S of the interface 520, the optical film 500 can easily emit image light in a direction inclined in the first direction D1 relative to the front direction (normal direction) of the display device 10.

[0272] like Fig.14As shown, the cross-sectional shape of the second layer 505 is a substantially trapezoidal shape with a long base on the substrate 501 side and a short base on the side opposite to the substrate 501. That is, the cross-sectional shape of the second layer 505 is such that the width along the first direction D1 increases as it approaches the substrate 501. Here, "the width along the first direction D1 increases as it approaches the substrate 501" not only means that the width along the first direction D1 continuously changes according to the distance from the substrate 501, but also means that it does not include a portion where the width along the first direction D1 decreases as it approaches the substrate 501, and therefore, it also includes a case where the width along the first direction D1 changes in stages according to the distance from the substrate 501. However, it is preferred that the cross-sectional shape of the second layer 505 continuously changes according to the distance from the substrate 501.

[0273] In addition, the legs of the trapezoidal shape may be curved instead of straight lines for the cross-sectional shape of the second layer 505. That is, the side surface of the second layer 505 may be a curved surface. By changing the cross-sectional shape of the second layer 505, the inclined surface 520S of the optical interface 520 between the second layer 505 and the first layer 504 is changed, so that the desired optical characteristics can be exerted by the shape of the interface 520.

[0274] In addition, the pitch of the plurality of second layers 505 arranged in the first direction D1 is smaller than the pitch of the pixels of the liquid crystal panel 15. In particular, the ratio of the pitch of the pixels of the liquid crystal panel 15 to the pitch of the second layers 505 arranged in the first direction D1 is preferably 1 / 5 or less, and more preferably 1 / 10 or less. Specifically, the pitch of the second layers 505 arranged in the first direction D1 is, for example, 35 μm or less.

[0275] The second layer 505 is transparent and can be formed by, for example, placing an ultraviolet curable resin such as urethane acrylate on the substrate 501 and curing the resin by irradiating the substrate with ultraviolet rays.

[0276] like Fig.13 and Fig.14 As shown in FIG. 1 , the first layer 504 is provided to fill the space between the adjacent portions of the second layer 505 extending in the first direction D1. In addition, the first layer 504 is transparent. Furthermore, the first layer 504 has adhesiveness. The adhesiveness of the first layer 504 enables the optical film 500 and the liquid crystal panel 15 to be bonded together. That is, the optical film 500 and the liquid crystal panel 15 can be bonded together without separately providing an adhesive layer for bonding the optical film 500 and the liquid crystal panel 15. Such a first layer 504 can be formed of, for example, an acrylic adhesive film or an ultraviolet curing adhesive.

[0277] The refractive index of the second layer 505 is higher than that of the first layer 504. If the difference between the refractive index of the second layer 505 and the refractive index of the first layer 504 becomes larger, it is easy to exert the optical effect at the interface 520 between the second layer 505 and the first layer 504. Specifically, the difference between the refractive index of the second layer 505 and the refractive index of the first layer 504 is preferably 0.05 or more and 0.25 or less, and more preferably 0.10 or more and 0.20 or less. In addition, the refractive index of the second layer 505 is, for example, 1.6 or more, and the refractive index of the first layer 504 is, for example, 1.49 or less. The comparison between the refractive index of the second layer 505 and the refractive index of the first layer 504 can be confirmed, for example, by the refraction direction of light incident on the interface between the second layer 505 and the first layer 504, or the total reflection condition. In addition, the specific value of the refractive index can be measured by using, for example, an Abbe refractometer (for example, RX-7000α manufactured by ATAGO Corporation).

[0278] The colored layer 550 absorbs a part of the light to be transmitted. The colored layer 550 is stacked on the second layer 505 side of the optical functional layer 503. In the example shown in the figure, the colored layer 550 is arranged between the substrate 501 and the optical functional layer 503. The colored layer 550 can also function as a primer layer for bonding the substrate 501 and the optical functional layer 503.

[0279] The coloring layer 550 includes: a transparent binder resin 551; and a plurality of coloring members 552 contained in the binder resin 551. The binder resin 551 is composed of, for example, a polyurethane resin. The coloring member 552 is, for example, a dye or a pigment having an average particle size of 1 μm or more and 10 μm or less, or a coloring bead colored with them. The particle size of the coloring member 552 can be measured, for example, based on an SEM image. When the coloring member 552 is too large, it will cause a local loss of light used for the image and reduce the display quality of the image, so the size of the coloring member 552 is preferably within the above range. For the coloring member 552, it is appropriately selected from dyes or pigments of various colors so that it can absorb light of a specific color. Preferably, the coloring member 552 is a dark color such as black composed of pigments such as carbon black and titanium black so that it can absorb light of all visible light wavelengths. When the coloring member 552 is a particle containing carbon black, the particle can contain carbon black and an acrylic styrene copolymer as a base resin for retaining the carbon black. In addition, in the case where the coloring material 552 is a particle containing carbon black, the particle size of the particle is determined by the particle size of the secondary agglomerate (hair root). It should be noted that the dark color means that the lightness represented by the value of L* among L*, a* and b* which can be measured according to JIS Z8781-4:2013 is less than 50. The lightness value can be measured, for example, using a combination of a hyperspectral camera (HSI-1000 manufactured by JFE Techno Research Co., Ltd.) and an optical microscope. In the opinion of the inventors of the present application, from the viewpoint of ensuring the absorptivity to light, the lightness (L*) of the coloring material is preferably less than 40, more preferably less than 30, and further preferably less than 20.

[0280] When such a coloring material 552 is a dye or a pigment, the coloring material 552 is contained in the coloring layer 550 at a ratio of 1.0 mass % to 5.0 mass %, preferably 2.0 mass % to 4.0 mass %. On the other hand, when the coloring material 552 is a colored bead, the coloring material 552 is contained in the coloring layer 550 at a ratio of 5.0 mass % to 25.0 mass %, preferably 10.0 mass % to 20.0 mass %.

[0281] In addition, for example, when the specific gravity of the coloring material 552 is extremely large or small, or when the specific gravity of the binder resin 551 is extremely small, the above-mentioned preferred range of mass % may change. In particular, when the coloring material 552 is a pigment or a colored bead colored by a pigment or a dye, the range of mass % is likely to change. Therefore, in the present embodiment, when the coloring material 552 is a pigment or a colored bead colored by a pigment or a dye, the conditions for the coloring material 552 to exert an optical function are determined as follows from the viewpoint of the number of coloring materials 552.

[0282] In the case where the coloring element 552 is a pigment or a coloring bead colored by a pigment or a dye, if the content of the coloring element 552 is determined from the viewpoint of the number of the coloring element 552, that is, if the above-mentioned weight % is converted into the number, the number of the coloring element 552 is 1 or more and 25 or less per 900 square μm when the optical film 500 is observed along the thickness direction of the color layer 550. More specifically, all the coloring elements 552 that can be seen through when the optical film 500 is observed in the thickness direction of the color layer 550 are counted, and the number of the coloring elements 552 counted is 1 or more and 25 or less.

[0283] The content of the coloring element 552 determined by the above-mentioned weight % and number is a value after curing of the components constituting the optical film 500. It should be noted that if the coloring element 552 is included in the coloring layer 550 in a ratio of 1.0 weight % or more and 5.0 weight % or less relative to the total mass of the coloring layer 550, the brightness will not be excessively reduced in the display device 10, and the effect of improving the visual recognition of the image as described later can be significantly obtained. Similarly, when the optical film 500 is observed in the thickness direction of the coloring layer 550, even if there are more than 1 and less than 25 per 900 square μm, the brightness will not be excessively reduced in the display device 10, and the effect of improving the visual recognition of the image as described later can be significantly obtained.

[0284] The above-mentioned weight % can be determined, for example, using the size of the coloring member 552 in the cross-sectional SEM image, the number of the coloring members 552 measured by an optical microscope, and the area of ​​the observation object. Specifically, the weight of each coloring member 552 is calculated based on the average diameter of the coloring member 552 obtained from the cross-sectional SEM image, and multiplied by the number of coloring members 552 per unit area confirmed when the surface of the coloring layer 550 is observed in the thickness direction through an optical microscope, thereby being able to calculate the weight % of the coloring member 552 in the coloring layer 550.

[0285] The number of coloring elements 552 per 900 μm 2 when the optical film 500 is observed in the thickness direction of the coloring layer 550 can be determined by capturing an image using an optical microscope and counting the number of coloring elements 552 in the image.

[0286] More specifically, the number of coloring pieces 552 can be determined as follows.

[0287] A sample is prepared by cutting the optical film 500 into a certain size. The size of the sample is preferably greater than 10×10 mm. This is because if the sample is small, it is difficult to fix it on the stage, and the influence of fine deformations such as warping becomes greater, so the difficulty of observation increases. Then, the sample is placed on the workbench of an optical microscope. Regarding the optical microscope, as long as it can be magnified more than 1000 times and can be observed in a transmitted light mode, the form is not limited. Then, for example, by observing the sample placed on the workbench at 1000 times, the coloring parts 552 contained in one layer or multiple layers are counted, thereby being able to count the number of coloring parts 552 contained in a unit area.

[0288] The thickness of the coloring layer 550 is preferably not less than 1 μm and not more than 13 μm, and more preferably not less than 4 μm and not more than 7 μm.

[0289] The refractive index of the coloring layer 550 is preferably greater than the refractive index of the substrate 501 and less than the refractive index of the second layer 505 of the optical functional layer 503. Specifically, the refractive index of the coloring layer 550 is preferably greater than or equal to 1.52 and less than or equal to 1.70. In this case, the loss of image light from the liquid crystal panel 15 can be suppressed, and the quality of the displayed image can be improved.

[0290] In addition, the coloring member 552 is not limited to being provided in the coloring layer 550, and can be provided at any position of the optical film 500 as long as it is closer to the second layer 505 side than the interface 520 between the second layer 505 and the first layer 504. For example, the coloring member 552 can be provided in a manner included in the second layer 505, or in a manner included in the substrate 501.

[0291] Next, the operation of the optical film 500 according to the present embodiment and the display device 10 including the optical film 500 will be described.

[0292] Image light emitted from the display surface 15A of the liquid crystal panel 15 enters the optical function layer 503 of the optical film 500. Fig.15 As shown, the image light incident on the optical function layer 503 first enters the first layer 504 , and then is incident on the interface 520 between the first layer 504 and the second layer 505 .

[0293] Image light traveling from the display surface 15A in the front direction and incident on the flat surface 520A of the interface 520 between the second layer 505 and the first layer 504 is as follows: Fig.15 As shown in FIG. 1 , the image lights L151 and L152 are not optically acted upon by the optical function layer 503 , that is, they are not refracted by the optical function layer 503 but are transmitted through the optical function layer 503 .

[0294] On the other hand, among the image light incident on the inclined surface 520S of the interface 420 between the second layer 505 and the first layer 504, the image light L153, ​​L154 traveling in the front direction and the image light L155, L156 traveling in the direction inclined relative to the front direction are refracted in such a manner that the inclination angle relative to the front direction is increased. After that, a part of the image light L153, ​​L155 is emitted from the optical functional layer 503, and another part of the image light L154, L156 is further refracted at the interface 520 between the second layer 505 and the first layer 504 and then emitted from the optical functional layer 503. These image lights L153 to L156 travel in the direction inclined more greatly relative to the front direction due to the refraction occurring at the interface 520 between the second layer 505 and the first layer 504 when passing through the optical functional layer 503. That is, due to the refraction effect at the interface 520 between the second layer 505 and the first layer 504, when the image light passes through the optical function layer 503, Fig.15 As shown, the angle formed by the traveling direction of the image light relative to the front direction tends to become larger. Therefore, the image light is easily emitted in the direction inclined from the front direction to the first direction D1. Therefore, the image light can be clearly observed even from the direction inclined relative to the first direction D1. That is, the viewing angle of the image from the display device 10 can be expanded.

[0295] In addition, a portion of the image light that has passed through the optical function layer 503 (in Fig.15 In the example shown, the image light L152, L153) is absorbed by the coloring element 552 of the coloring layer 550. The image light not absorbed by the coloring element 552 of the coloring layer 550 (in Fig.15 In the example shown, image light (L151, L154, L155, L156) passes through the optical film 500 and is observed by an external observer.

[0296] However, if such an optical film capable of expanding the viewing angle of an image is arranged opposite to the display surface of a liquid crystal panel, light that deteriorates the visual recognition of the image may be generated. As light that deteriorates the visual recognition of the image generated by the arrangement of the optical film, there is, for example, light that is formed by reflection of light from the outside on the inside of the optical film. In order to suppress the deterioration of the visual recognition of the image, it is required to absorb such light.

[0297] In order to absorb such light, it is considered to add a coloring member that absorbs light to the optical film. However, such a coloring member will also absorb the image light from the display device. Therefore, if the light that deteriorates the visual recognition of the image is to be absorbed, the visual recognition of the image itself will also be deteriorated. The inventors of the present application and others have conducted research and found that by studying the position of the coloring member in the optical film, the coloring member can be used to effectively absorb the light that deteriorates the visual recognition of the image. In other words, it was found that the light that deteriorates the visual recognition of the image can be efficiently absorbed while suppressing the deterioration of the visual recognition of the image. The following is an explanation of the principle that is presumed to be able to efficiently suppress the deterioration of the visual recognition of the image. However, the present embodiment is not limited to this speculation.

[0298] The optical film 500 of this embodiment is provided with a coloring member 552 on the side closer to the second layer 505 than the interface 520 between the second layer 505 and the first layer 504 of the optical functional layer 503. In this case, Fig.16 As shown, a portion of the light incident on the optical film 500 from the outside of the display device 10 is absorbed by the coloring element 552 of the coloring layer 550, as light L161. Alternatively, another portion of the light incident on the optical film 500 from the outside is transmitted through the coloring layer 550 and incident on the interface 520 between the second layer 505 and the first layer 504 of the optical functional layer 503, as light L162. Thereafter, the light L162 is reflected at the interface 520, and then is incident on the coloring layer 550 again, and is absorbed by the coloring element 552 of the coloring layer 550. If the refractive index of the second layer 505 of the optical functional layer 503 is greater than the refractive index of the first layer 504, the reflection of the light in the optical film 500 is particularly likely to occur at the interface 520. The light incident from the outside and reflected inside the optical film 500 passes through the coloring layer 550 including the coloring element 552 twice. Therefore, by providing the coloring member 552 at a position closer to the front side than the interface 520, that is, the second layer 505 side, it is possible to efficiently absorb light incident from the outside and reflected inside the optical film 500. That is, it is possible to suppress the light L162 incident from the outside to the optical film and reflected in the optical film, or the light L161 to be reflected from being emitted to the outside, thereby suppressing the following situation: the visual recognition of the image displayed by the display device 10 equipped with the optical film 500 is deteriorated due to such light.

[0299] In addition, light from the outside that is reflected inside the liquid crystal panel 15 or the surface light source device 20 also deteriorates the visual recognition of the image in the same manner as the light reflected inside the optical film 500. By providing the coloring member 552 in the optical film 500, the light incident from the outside and reflected inside the liquid crystal panel 15 and the like passes through the coloring layer 550 including the coloring member 552 twice. Therefore, by efficiently absorbing the light incident from the outside and reflected inside the optical film 500, it is possible to suppress the light from being emitted to the outside, thereby suppressing the deterioration of the visual recognition of the image.

[0300] On the other hand, Fig.15 As shown, the image light emitted from the liquid crystal panel 15 passes through the coloring layer 550 including the coloring member 552 only once before passing through the optical film 500 and being emitted from the display device 10. Therefore, compared with the light from the outside, the image light is less likely to be absorbed by the coloring member 552. In this way, compared with the image light, the light from the outside is more easily absorbed, so that the deterioration of the image visibility caused by the absorption of the image light can be suppressed, and the light reflected inside the optical film and the like, which deteriorates the image visibility, can be efficiently absorbed.

[0301] The coloring material 552 may be included in the base material 501 or the second layer 505, but is preferably included in the coloring layer 550. By including the coloring material 552 in the coloring layer 550, the coloring material 552 can be easily provided at a desired position of the optical film 500.

[0302] Furthermore, the coloring material 552 is contained in the coloring layer 550 at a ratio of 1.0 mass % or more and 5.0 mass % or less, preferably at a ratio of 2.0 mass % or more and 4.0 mass % or less. By containing the coloring material 552 at a ratio of 1.0 mass % or more, the coloring material 552 can fully absorb the light that passes through the coloring layer 550 twice and enters from the outside and is reflected inside the optical film 500. In addition, by containing the coloring material 552 at a ratio of 2.0 mass % or more, the light reflected inside the optical film 500 can be fully absorbed by the coloring material 552. That is, it is possible to suppress the light L162 that enters the optical film from the outside and is reflected in the optical film, or the light L161 to be reflected from being emitted to the outside, thereby suppressing the deterioration of the visual recognition of the image. In addition, by containing the coloring material 552 at a ratio of 5.0 mass % or less, it is possible to effectively suppress the following situation: excessive absorption of the image light that passes through the coloring layer 550 once and is emitted from the liquid crystal panel 15, thereby deteriorating the visual recognition of the image. Furthermore, by containing 5.0 mass % or less of the coloring material 552, it is possible to more effectively prevent the coloring material 552 from excessively absorbing image light and deteriorating image visibility. Specifically, the proportion of image light absorbed in the coloring layer 550 can be reduced to 10% or less.

[0303] In addition, the coloring member 552 is black. The black coloring member 552 can absorb light of all visible light wavelengths. Therefore, it is possible to avoid the following situation: the color reproducibility of the image is damaged due to light incident on the optical film from the outside and reflected in the optical film. In addition, it is possible to avoid the following situation: only the color of light of a specific wavelength is absorbed and the color reproducibility of the image light is damaged.

[0304] Hereinafter, the optical film 500 according to the fifth embodiment will be described in more detail using examples, but the optical film 500 according to the fifth embodiment is not limited to the following examples.

[0305] As an embodiment, a reference example and a comparative example, optical films having different positions of coloring parts or different contents of coloring parts were prepared. Each optical film has a substrate and an optical functional layer laminated on the substrate. The optical functional layer has a second layer and a first layer laminated on the second layer. The refractive index of the second layer is greater than the refractive index of the first layer. Specifically, the refractive index of the second layer is 1.65, and the refractive index of the first layer is 1.48. The interface between the second layer and the first layer is concave-convex.

[0306] In Reference Example 1, the optical film does not contain a coloring member. In Examples 3 and 4, a coloring layer containing a black coloring member is arranged between the substrate and the optical functional layer of the optical film of Reference Example 1. In Example 3, the coloring member is contained in the coloring layer at a ratio of 2.0 mass %. In Example 4, the coloring member is contained in the coloring layer at a ratio of 4.0 mass %. On the other hand, in Reference Example 2, similarly to Reference Example 1, the optical film does not contain a coloring member. In Comparative Examples 3 and 4, a black coloring member is contained in the first layer of the optical film of Reference Example 2. In Comparative Example 3, the coloring member is contained in the first layer at a ratio of 2.0 mass %. In Comparative Example 4, the coloring member is contained in the first layer at a ratio of 4.0 mass %.

[0307] These optical films were placed face to face with the display surface of the display device, and the front brightness of the display device with the optical film was measured in a state where a white image was displayed on the display surface. In addition, the visible light reflectance of each optical film was measured. Regarding the visible light reflectance, the reflectance (SCI) of total reflection including regular reflection was measured using a spectrocolorimeter / colorimeter (CM-600d manufactured by Konica Minolta).

[0308] The measurement results of the front brightness and visible light reflectance of each example, comparative example and reference example are shown in the following Table 21. In Examples 3 and 4, the ratio of the front brightness to Reference Example 1 was calculated, and in Comparative Examples 3 and 4, the ratio of the front brightness to Reference Example 2 was calculated.

[0309] [Table 21]

[0310] <![CDATA[Front luminance (cd / m 2 )]]> Front brightness ratio Total reflection reflectivity Reference Example 1 684 1 2.63％ Example 3 649 0.949 2.36％ Example 4 617 0.902 2.18％ Reference Example 2 705 1 2.64％ Comparative Example 3 665 0.943 2.44％ Comparative Example 4 636 0.902 2.33％

[0311] According to the comparison of the front brightness ratio of Reference Example 1, Example 3 and Example 4 with Reference Example 2, Comparative Example 3 and Comparative Example 4, it can be seen that if the coloring part is added, the front brightness is reduced regardless of the position of the coloring part. Specifically, from the results of the front brightness ratio of Example 3 and Comparative Example 3, it can be seen that when the coloring part is contained at a ratio of 2.0 mass%, the front brightness is reduced by about 5% regardless of the position of the coloring part. In addition, from the results of the front brightness ratio of Example 4 and Comparative Example 4, it can be seen that when the coloring part is contained at a ratio of 4.0 mass%, the front brightness is reduced by about 10% regardless of the position of the coloring part. In order to suppress the reduction in front brightness, specifically, in order to make the reduction ratio of the front brightness less than 10%, it is preferred that the content of the coloring part is less than 4.0 mass%.

[0312] On the other hand, it can be seen from the comparison of the reflectance of total reflection of Reference Example 1, Examples 3 and 4 with Reference Example 2, Comparative Example 3 and Comparative Example 4 that the reflectance differs depending on the position where the coloring member is provided. That is, it can be seen that by providing the coloring member on the second layer side of the interface, specifically between the substrate and the optical functional layer, as in Examples 3 and 4, it can be seen that the reflection can be suppressed compared to the case where the coloring member is provided on the first layer side of the interface, specifically in the first layer, as in Comparative Examples 3 and 4.

[0313] In addition, it can be seen from the comparison between Example 3 and Example 4 that the emission of reflected light can be further suppressed by increasing the content of the coloring material. Specifically, it can be seen from the comparison between Example 3 and Comparative Example 1 that the emission of reflected light in the optical laminate can be effectively suppressed by setting the ratio of the coloring material to 2.0 mass % or more.

[0314] From the above content, it can be seen that by studying the position of setting the coloring part, specifically, by setting the coloring layer on the side of the second layer closer to the interface between the second layer and the first layer, the reduction in front brightness can be suppressed, that is, the reflection of external light incident on the optical film can be suppressed without increasing the amount of coloring part.

[0315] Above, each embodiment of the present invention has been described, but the present invention is not limited to the structure in the above-mentioned embodiment, and various changes can also be applied. In addition, the structure in each embodiment can also be appropriately combined. In this case, the structure in more than 3 embodiments can also be combined.

[0316] For example, in Fig.17In the variation shown, the optical film 600 includes a substrate 601, a front member 602 disposed on the front side of the substrate 601, and an optical functional layer 603 disposed on the back side of the substrate 601. In this variation, the optical functional layer 603 includes a first layer 604, a second layer 605 having a refractive index different from that of the first layer 604 and bonded to the first layer 604 on the substrate 601 side of the first layer 604, and a third layer 606 having a refractive index different from that of the first layer 604 and stacked on the side of the first layer 604 opposite to the second layer 605. In addition, the first interface between the first layer 604 and the second layer 605 is concave-convex. The second interface between the first layer 604 and the third layer 606 is concave-convex. In addition, the coloring member 652 is disposed on the side closer to the second layer 605 than the first interface. Moreover, the refractive indexes of the second layer 605, the substrate 601, and the front member 602 become smaller in sequence. That is, Fig.17 The optical film 600 of the modified example shown has the features of the optical film 100 of the first embodiment, the features of the optical film 400 of the fourth embodiment, and the features of the optical film 500 of the fifth embodiment. According to such an optical film 600, the effects of the optical film 100 of the first embodiment, the optical film 400 of the fourth embodiment, and the optical film 500 of the fifth embodiment can be achieved.

[0317] Furthermore, other combinations of the structures in the respective embodiments are of course also possible.

[0318] In addition, for example, in each of the above-mentioned embodiments, the lens portion 110 has a strip shape along the film surface, but Fig.18 As shown, the lens portions 110 may also be arranged in a matrix on the film surface. Fig.18 In the example, the lens portion 110 is a quadrangular pyramid, but it may also be a cone, a hexagonal pyramid, an octagonal pyramid, etc. In addition, the optical film 100 or 100-2 of the first and second embodiments described above may also be integrated with a polarizing plate (upper polarizing plate 13) and circulated in the form of a polarizing plate with an optical film. In addition, the optical film 100-3 of the third embodiment described above may be integrated with a circular polarizing plate 220 according to the application and circulated in the form of a polarizing plate with an optical film.

[0319] Furthermore, in the above-mentioned embodiments, the polarizing plate (upper polarizing plate) 13 is bonded to the low refractive index layer 104 (first layer 404, 504 of optical film 400, 500) of the optical film 100. However, the polarizer of the polarizing plate may be bonded to the optical film.

[0320] More specifically, in each of the above-mentioned embodiments, the polarizing plate 13 includes a pair of protective films 13A and a polarizer 13B disposed between the pair of protective films 13A. Therefore, the protective film 13A of the polarizing plate 13 is bonded to the low refractive index layer 104 (first layer 404, 504) of the optical film. In the case where the layer of the optical film that contacts the polarizing plate 13, such as the low refractive index layer 104 (first layer 404, 505), also serves as an adhesive layer bonded to the polarizing plate 13, the polarizing plate 13 is directly bonded to the optical film. Alternatively, as Fig.19 As shown, when the adhesive layer 30 is disposed between the optical film and the polarizing plate 13 , the polarizing plate 13 is bonded to the optical film via the adhesive layer 30 .

[0321] However, the protective film 13A may be omitted, and the polarizer 13B may be bonded to the low refractive index layer (first layer) of the optical film. When the layer of the optical film that contacts the polarizer 13B, such as the low refractive index layer 104 (first layer 404, 505), also serves as an adhesive layer bonded to the polarizing plate 13, the polarizer 13B may be directly bonded to the optical film. Alternatively, Fig. 20 As shown, when the adhesive layer 30 is disposed between the optical film and the polarizer 13B, the polarizer 13B is bonded to the optical film via the adhesive layer 30 .

[0322] Description of symbols

[0323] 10, 10-2, 10-3: display device;

[0324] 12: liquid crystal layer;

[0325] 13: Upper polarizing plate;

[0326] 14: Lower polarizing plate;

[0327] 15: LCD panel;

[0328] 15A: display surface;

[0329] 15B: back;

[0330] 20: surface light source device;

[0331] 21: luminous surface;

[0332] 30: adhesive layer;

[0333] 100, 100-2, 100-3, 400, 500, 600: optical film;

[0334] 101, 401, 501, 601: substrate;

[0335] 101A: front;

[0336] 101B: back side;

[0337] 102, 402, 502, 602: front parts;

[0338] 103, 403, 503, 603: optical functional layer;

[0339] 104, 404, 504, 604: low refractive index layer (first layer);

[0340] 105, 405, 505, 605: high refractive index layer (second layer);

[0341] 406, 606: Layer 3;

[0342] 105A: layer body;

[0343] 110: lens portion;

[0344] 120, 420, 520: concave-convex shape (interface);

[0345] 120S, 420S, 520S: side (bevel);

[0346] 121: concave part;

[0347] 121A: flat part;

[0348] 122: convex part;

[0349] 122A: flat part;

[0350] 215: organic LED panel;

[0351] 220: circular polarizing plate;

[0352] 230: touch panel;

[0353] 240: cover glass;

[0354] 251: first adhesive layer;

[0355] 252: second adhesive layer;

[0356] 253: The third adhesive layer.

Claims

1. An optical film, wherein: The optical film comprises: Base material; A front member disposed on the front side of the substrate; and An optical functional layer is disposed on the back side of the substrate. The optical function layer comprises: a first layer; and a second layer having a refractive index different from that of the first layer and bonded to the first layer on the substrate side of the first layer. The first interface between the first layer and the second layer is in a concave-convex shape, The refractive indexes of the second layer, the substrate and the front member decrease in sequence. The refractive index of the front element is 1.37 or 1.40, The difference between the refractive index difference between the second layer and the substrate and the refractive index difference between the substrate and the front member is 0.02 or less in absolute value.

2. The optical film according to claim 1, wherein: The difference between the refractive index difference between the second layer and the substrate and the refractive index difference between the substrate and the front member is zero.

3. The optical film according to claim 1, wherein The thickness of the substrate is 25 μm or more and 120 μm or less, The total light transmittance of the substrate is above 87%.

4. The optical film according to claim 1, wherein The optical film further includes a flat layer disposed between the second layer of the optical functional layer and the substrate. When the average of the refractive index of the second layer and the refractive index of the substrate is defined as M, the refractive index of the flat layer is 0.98M to 1.02M.

5. The optical film according to claim 1, wherein The refractive index of the first layer is smaller than the refractive index of the second layer.

6. The optical film according to claim 1, wherein: The refractive index of the first layer is greater than the refractive index of the second layer.

7. The optical film according to claim 1, wherein: The concave portions and the convex portions in the concavo-convex shape each have a flat portion extending along the film surface of the optical film.

8. The optical film according to claim 1, wherein: The optical function layer further includes a third layer stacked on the first layer on the side opposite to the second layer. The refractive index of the first layer is different from the refractive index of the third layer, The second interface between the first layer and the third layer has a concavo-convex shape.

9. The optical film according to claim 8, wherein: The refractive index of the first layer is smaller than the refractive index of the third layer.

10. The optical film according to claim 8, wherein: The refractive index of the first layer is greater than the refractive index of the third layer.

11. The optical film according to claim 8, wherein: The pitch of the concavities and convexities of the concavo-convex shape of the first interface is larger than the pitch of the concavo-convexities of the concavo-convex shape of the second interface.

12. The optical film according to claim 1, wherein: A coloring material is provided on the second layer side relative to the first interface.

13. The optical film according to claim 12, wherein: The optical film further comprises a colored layer laminated on the second layer side of the optical functional layer. The coloring member is included in the coloring layer.

14. The optical film according to claim 13, wherein: The coloring material is contained in the coloring layer at a ratio of 1.0 mass % to 5.0 mass %.

15. The optical film according to claim 12, wherein: The colored piece is black.

16. The optical film according to claim 12, wherein: In the optical film, the first layer has adhesiveness.

17. A display device, wherein: The display device comprises: The optical film according to any one of claims 1 to 16; and LCD panel, The optical film is arranged such that the first layer faces the display surface side of the liquid crystal panel relative to the second layer.

18. A display device, wherein: The display device comprises: The optical film according to any one of claims 1 to 16; and Organic LED panels, The optical film is arranged such that the first layer faces the display surface side of the organic LED panel relative to the second layer.

19. A polarizing plate with an optical film, wherein: The polarizing plate with an optical film comprises: The optical film according to any one of claims 1 to 16; and A polarizing plate is bonded to the optical film.

20. The polarizing plate with an optical film according to claim 19, wherein The layer of the optical film in contact with the polarizing plate also serves as an adhesive layer for bonding to the polarizing plate.

21. The polarizing plate with an optical film according to claim 19, wherein The polarizing plate with an optical film further includes an adhesive layer between the optical film and the polarizing plate.

22. A polarizing plate with an optical film, wherein: The polarizing plate with an optical film comprises: The optical film according to any one of claims 1 to 16; a polarizer, which is bonded to the optical film; and an adhesive layer for bonding the optical film to the polarizer, The polarizer is attached to the optical film only via the adhesive layer.

23. A polarizing plate with an optical film, characterized in that: The polarizing plate with an optical film comprises: The optical film according to any one of claims 1 to 16; and a polarizer, which is bonded to the optical film, The layer of the optical film in contact with the polarizer also serves as an adhesive layer for bonding to the polarizer. The polarizer is directly attached to the optical film.

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