Optical Film and Display Device

Abstract

To provide an optical film that can suppress deterioration of visibility of a display image due to moire while preferably securing an axial symmetry optical characteristic, and an optical film attached display device comprising the optical film.SOLUTION: An optical film comprises a plurality of optical elements. In a case where a first reference line that is parallel to a film surface is extended in a horizontal direction from a first optical element of the plurality of optical elements, a second optical element which is adjacent to the first optical element is arranged with a predetermined interval in a direction having a first angle to the first reference line. A third optical element that is adjacent to the first optical element is arranged with a predetermined interval in a direction having a second angle to a second reference line which is orthogonal to the first reference line and is parallel to the film surface. Other optical element of the plurality of optical elements is arranged with a predetermined interval to an optical element which is adjacent in a direction having the first angle, and is arranged with a predetermined interval to an optical element which is adjacent in a direction having the second angle.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to an optical film that optically acts on light for forming a display image. The present disclosure also relates to a display device including the optical film.

Background Art

[0002] A liquid crystal display device, which is an example of a display device, is used in various fields. Also recently, organic LED (Organic Light Emitting Diode) display devices are becoming widespread.

[0003] In a liquid crystal display device, the color tone of a display image within the viewing angle may change significantly due to, for example, a change in the intensity of light according to the viewing angle, light leakage in an oblique direction, and the like. Hereinafter, the display image may be simply referred to as an image.

[0004] On the other hand, in an organic LED display device, blue shift easily occurs in an image viewed obliquely. Blue shift refers to a phenomenon in which an image viewed in an oblique direction becomes bluer than an image viewed directly. That is, even in an image displayed by an organic LED display device, for example, the color tone within the viewing angle may change significantly due to such blue shift.

[0005] Color changes within the viewing angle as described above can degrade the display quality of an image. Therefore, the applicant of the present application previously proposed a technique for suppressing such color changes in JP6447654B. In this technique, light emitted from a liquid crystal panel is diffused to mix a plurality of types of light having different colors within the viewing angle. Thereby, variation in color tone within the viewing angle is suppressed.

[0006] In the optical film of JP6447654B, a plurality of optical elements formed at the interface between the high refractive index layer and the low refractive index layer are columnar. And these optical elements extend in a long shape across the opposite edges of the optical film. Note that the above optical elements are parts that can also be called an optical functional part, an optical structure, an optical interface part, etc.

[0007] On the other hand, US9507059B2 proposes an optical film having a plurality of optical elements arranged two-dimensionally. US9507059B2 discloses a frustum-shaped optical element, according to which light can be uniformly diffused in all directions. Here, as the shape of such an optical element, for example, a frustum of a square pyramid shape may be used. When such a frustum of a square pyramid-shaped optical element is used, for example, it is possible to suitably improve the display quality in two directions, the left-right direction and the up-down direction, where appearance is emphasized.

Summary of the Invention

[0008] The optical film in which the optical elements are arranged two-dimensionally can generate moiré by overlapping with pixels on the display device. That is, in the optical film in which the optical elements are arranged two-dimensionally, due to the optical function of the optical elements, in-plane luminance unevenness or transmittance unevenness when observed from a specific direction may occur, and that can form a lattice pattern. For example, when the optical element is frustum of a square pyramid-shaped, the transmittance at the side surface when observed from the front may decrease with respect to the tip. Also, in the case of a frustum of a square pyramid shape, the transmittance may also change at the ridge lines or joints on the side surface. Such a change in transmittance can form a lattice pattern. Also, when the optical element is a diffraction grating, since the optical function can change at its joints, the transmittance changes and a lattice pattern can be formed. On the other hand, a lattice pattern is also formed between a plurality of pixels. Moiré can occur due to the overlap of such lattice patterns. Note that general moiré means a relatively rough stripe pattern, but in this specification, the general term for the pattern generated by the overlap will be called moiré. For example, a fine particle-like light and dark pattern is also called moiré.

[0009] Here, moiré patterns generated by the overlap of two grating patterns can be reduced by tilting one grating pattern with respect to the other. That is, it is what is called bias. However, in this method, for example, when the optical element of an optical film is in the shape of a frustum of a square pyramid, simply tilting the entire optical film with respect to the pixels may cause discomfort to the viewer's vision.

[0010] Specifically, when an optical film having a frustum-of-a-square-pyramid-shaped optical element is incorporated into a display device in which the up-down, left-right directions are defined, usually, two of the four side surfaces of the optical element are made parallel to the up-down direction, and the other two side surfaces are made parallel to the left-right direction. That is, usually, since the display device is designed such that the optical characteristics of the display image are axisymmetric with respect to the up-down axis and the left-right axis, the optical film is arranged as described above. Here, when the optical film is simply tilted to reduce moiré, the side surfaces of the optical element are tilted with respect to the up-down direction or the left-right direction. At this time, the direction of the peak of the optical function exhibited by the optical element is tilted with respect to the up-down and left-right directions, and as a result, there is a possibility of giving discomfort to the viewer's vision.

[0011] On the other hand, when a frustum-of-a-cone-shaped optical element is used instead of a frustum-of-a-square-pyramid-shaped optical element, the optical function of the optical element does not change depending on the orientation of the optical element with respect to the pixels. However, for example, when improvement of display quality in specific two directions such as the up-down direction and the left-right direction is particularly desired, it cannot be said that good results are necessarily obtained. In addition, a master for replication or a roll type is generally produced by cutting a metal plate or a metal layer with a bite. Although straight cutting can be used for a frustum of a square pyramid, rotary cutting is required for a frustum of a cone, so the production time and cost increase.

[0012] The present disclosure has been made in consideration of the above circumstances, and is an optical film that transmits light emitted from pixels for forming a display image. When displaying a display image by transmitting the light emitted from the pixels, it preferably ensures optical characteristics having axial symmetry with respect to two orthogonal axes that serve as a reference for the pixel array in the display image, and suppresses a decrease in visibility of the display image due to moiré. An object of the present disclosure is to provide an optical film and a display device with an optical film including the same.

[0013] An optical film according to an embodiment is an optical film including a plurality of optical elements. When a first reference line parallel to the film surface is extended horizontally from a first optical element among the plurality of optical elements, a second optical element adjacent to the first optical element is arranged at a predetermined interval in a direction forming a first angle with respect to the first reference line, and a third optical element adjacent to the first optical element is arranged at a predetermined interval in a direction forming a second angle with respect to a second reference line orthogonal to the first reference line and parallel to the film surface. Among the plurality of optical elements, other optical elements are also arranged at a predetermined interval from adjacent optical elements in the direction forming the first angle, and are arranged at a predetermined interval from adjacent optical elements in the direction forming the second angle.

[0014] Centers of the optical elements adjacent in the direction of the first reference line are not aligned on the first reference line, centers of the optical elements adjacent in the direction of the second reference line are not aligned on the second reference line, and the optical elements may have sides parallel to the first reference line or the second reference line.

[0015] Centers of the optical elements adjacent in the direction forming the first angle may be aligned in the direction forming the first angle, and centers of the optical elements adjacent in the direction forming the second angle may be aligned in the direction forming the second angle.

[0016] The optical elements may be arranged at a constant pitch in the direction forming the first angle and may be arranged at a constant pitch in the direction forming the second angle.

[0017] The pitch in the direction forming the first angle and the pitch in the direction forming the second angle may each be 2 μm or more and 50 μm or less.

[0018] When viewed in the normal direction of the film surface, the opposing sides of the optical elements adjacent to each other in the direction forming the first angle are parallel to each other, and when viewed in the normal direction of the film surface, the opposing sides of the optical elements adjacent to each other in the direction forming the second angle may be parallel to each other.

[0019] The first angle may be 5 degrees or more and 40 degrees or less.

[0020] The second angle may be 5 degrees or more and 40 degrees or less.

[0021] The side surface of the optical element may have an element side surface that is non-parallel to the direction forming the first angle and the direction forming the second angle.

[0022] The direction passing through both ends of the element side surface in a direction parallel to the film surface may be non-parallel to the direction forming the first angle and the direction forming the second angle at an angle different from 45 degrees.

[0023] An optical film according to an embodiment is an optical film including a plurality of optical elements, wherein the plurality of optical elements are arranged in each of a first direction and a second direction that are parallel to the film surface and intersect each other, and when viewed in the normal direction of the film surface, the tangents of a pair of opposing sides of the optical elements are non-parallel to the first direction and the second direction.

[0024] An optical film according to an embodiment is an optical film including a plurality of optical elements, wherein the plurality of optical elements are arranged such that the center of each optical element is positioned in each of a first direction and a second direction that are parallel to the film surface and intersect each other, and when viewed in the normal direction of the film surface, the tangents of a pair of opposing sides of the optical elements are non-parallel to the first direction and the second direction.

[0025] An optical film according to an embodiment is an optical film including a plurality of optical elements, wherein the plurality of optical elements are arranged in a first direction and a second direction that are parallel to the film surface and intersect each other, and each of the optical elements protrudes to one side or the other side in the normal direction of the film surface and has a side surface between a tip end and a base end, or is recessed to one side or the other side in the normal direction of the film surface and has a side surface between a recess start edge and a bottom end. The side surface has a pair of first element side surfaces facing each other and a pair of second element side surfaces facing each other in a direction orthogonal to the direction in which the pair of first element side surfaces face each other. The normal direction of each of the pair of first element side surfaces is non-parallel to a plane including the first direction and the normal direction of the film surface and a plane including the second direction and the normal direction of the film surface, and / or the normal direction of each of the pair of second element side surfaces is non-parallel to a plane including the first direction and the normal direction of the film surface and a plane including the second direction and the normal direction of the film surface.

[0026] The optical elements may be arranged at a constant pitch in each of the first direction and the second direction.

[0027] When viewed in the normal direction of the film surface, adjacent optical elements may not be aligned along a plane including the normal direction of each of the pair of first element side surfaces and the normal direction of the film surface, and may not be aligned along a plane including the normal direction of each of the pair of second element side surfaces and the normal direction of the film surface.

[0028] When viewed in the normal direction of the film surface, a direction parallel to a plane including the normal direction of each of the pair of first element side surfaces and the normal direction of the film surface may form an angle of 5 degrees or more and 40 degrees or less, or 50 degrees or more and 85 degrees or less with the first direction. Also, a direction parallel to a plane including the normal direction of each of the pair of second element side surfaces and the normal direction of the film surface may form an angle of 5 degrees or more and 40 degrees or less, or 50 degrees or more and 85 degrees or less with the first direction.

[0029] When viewed in the normal direction of the film surface, the optical film is rectangular, the first direction and the second direction are each non-parallel to the four sides of the rectangular optical film, the four sides include a pair of first sides facing each other and a pair of second sides facing each other in a direction orthogonal to the direction in which the pair of first sides face each other, and when viewed in the normal direction of the film surface, the pair of first element side surfaces face each other in the direction in which the second side extends, and the pair of second element side surfaces may face each other in the direction in which the first side extends.

[0030] The optical elements adjacent to each other in the first direction are adjacent to each other with a gap in either the direction in which the pair of first sides face each other or the direction in which the pair of second sides face each other, and a first duty defined by dividing the dimension at the midpoint in the normal direction of the film surface between the pair of first element side surfaces or the pair of second element side surfaces by the pitch of the optical elements in the first direction may be 0.5 or more and 0.8 or less.

[0031] The optical elements adjacent to each other in the second direction are adjacent to each other with a gap in either the direction in which the pair of first sides face each other or the direction in which the pair of second sides face each other, and a second duty defined by dividing the dimension at the midpoint in the normal direction of the film surface between the pair of first element side surfaces or the pair of second element side surfaces by the pitch of the optical elements in the second direction may be 0.5 or more and 0.8 or less.

[0032] The optical element is in the shape of a frustum of a square pyramid, and its front end surface may be parallel to the film surface.

[0033] The ridge lines on the side surfaces of the optical element may be rounded.

[0034] The optical element is a diffraction grating having a plurality of grooves that are recessed on one side or the other side in the normal direction of the film surface and are elongated in a direction parallel to the first side, and the normal direction of each of the first element side surfaces formed in each groove is non-parallel to the plane including the first direction and the normal direction of the film surface and the plane including the second direction and the normal direction of the film surface. The first element includes a diffraction grating, and a second element having a plurality of grooves that are recessed on one side or the other side in the normal direction of the film surface and are elongated in a direction parallel to the second side, and the normal direction of each of the second element side surfaces formed in each groove is non-parallel to the plane including the first direction and the normal direction of the film surface and the plane including the second direction and the normal direction of the film surface. The diffraction grating includes a second element, and in each of the first direction and the second direction, the first element and the second element may be arranged in a mixed manner.

[0035] In addition, a display device according to an embodiment includes a display panel in which a plurality of pixels are arranged in each of a first pixel arrangement direction and a second pixel arrangement direction orthogonal to the first pixel arrangement direction, and the optical film. The optical film is arranged on the plurality of pixels such that the first direction and the second direction, which are the arrangement directions of the optical elements, are non-parallel to the first pixel arrangement direction and the second pixel arrangement direction, respectively. When viewed in the normal direction of the film surface of the optical film, the normal direction of each of the pair of first element side surfaces is parallel to the first pixel arrangement direction, and the normal direction of each of the pair of second element side surfaces is parallel to the second pixel arrangement direction.

[0036] The display panel may be an organic LED panel or a liquid crystal panel.

[0037] The arrangement of sub-pixels in the pixel may be a pentile arrangement.

[0038] The pitch of the optical elements may be equal to or less than half of the width of the sub-pixels.

[0039] According to the present disclosure, when displaying a display image by transmitting light emitted from pixels, it is desirable to ensure optical characteristics that are axisymmetric with respect to two orthogonal axes serving as the reference of the pixel array in the display image, while suppressing a decrease in the visibility of the display image due to moiré.

Brief Description of the Drawings

[0040]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0041] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0042] In the present specification, terms such as "sheet", "film", and "plate" are not distinguished from each other based only on the difference in name. Therefore, for example, "sheet" is a concept that includes members that can also be called films or plates. Further, in the present specification, the "sheet surface (plate surface, film surface)" refers to the surface that coincides with the planar direction (surface direction) of the target sheet-like member when the target sheet-like member is viewed as a whole and globally. Furthermore, in the present specification, the normal direction of the sheet-like member refers to the normal direction to the sheet surface of the target sheet-like member.

[0043] <Display device> FIG. 1 is a front view of a display device 10 with an optical film (hereinafter simply referred to as the display device 10) including an optical film 100. FIG. 2 is a schematic cross-sectional view of a part of the display device 10 in the thickness direction Z of the display device 10. In the present embodiment, the optical film 100 forms the outermost surface of the display device 10. The display image of the display device 10 is projected onto the viewer side through the optical film 100.

[0044] In the figures used in the following description including FIGS. 1 and 2, the symbol X indicates the left-right direction of the display device 10. The symbol Y indicates the up-down direction of the display device 10 that is orthogonal to the left-right direction X. The thickness direction Z is a direction orthogonal to both the left-right direction X and the up-down direction Y.

[0045] As shown in FIG. 1, the optical film 100 in the illustrated example has a rectangular shape with a longitudinal direction in the up-down direction Y. The optical film 100 has a pair of first sides 100A, 100A that extend in the up-down direction Y and face each other in the left-right direction X, and a pair of second sides 100B, 100B that extend in the left-right direction X and are orthogonal to the direction in which the first sides 100A face each other, that is, face each other in the up-down direction Y.

[0046] As shown in FIG. 2, the display device 10 is configured by laminating an organic LED (Organic Light Emitting Diode) panel 15, a circular polarizing plate 20, a touch panel 30, a cover glass 40, and an optical film 100 in this order. The organic LED panel 15, the circular polarizing plate 20, the touch panel 30, and the cover glass 40 are also rectangular in shape with a longitudinal direction in the vertical direction Y. In the present embodiment, the optical film 100 forms the outermost surface of the display device 10, but other layers may form the outermost surface.

[0047] The display device 10 is configured as a smartphone as an example. However, the display device 10 may be a tablet terminal, a television, a computer display, a car navigation system, or the like.

[0048] The display surface (front surface) 15A of the organic LED panel 15 and the back surface of the circular polarizing plate 20 are bonded together by a first adhesive layer 51. The front surface of the circular polarizing plate 20 and the back surface of the touch panel 30 are bonded together by a second adhesive layer 52. The front surface of the touch panel 30 and the back surface of the cover glass 40 are bonded together by a third adhesive layer 53. Each of the adhesive layers 51 to 53 is a so-called OCA (Optical Clear Adhesive) and has a high light transmittance. Also, the optical film 100 is disposed on the front surface of the cover glass 40. In this example, the optical film 100 and the cover glass 40 are not bonded together by an adhesive layer. However, the optical film 100 and the cover glass 40 may be bonded together by an adhesive layer.

[0049] The organic LED panel 15 is an organic LED panel that adopts a microcavity structure. However, the organic LED panel 15 may be of other types such as a color filter method. Generally, in an organic LED panel, a blue shift is likely to occur in an image viewed obliquely, and the color change within the viewing angle may increase due to the blue shift. Therefore, in the display device 10, the optical film 100 is used to suppress the color change within the viewing angle.

[0050] The circular polarizing plate 20 has a polarizer and a retardation plate. The retardation plate is disposed on the organic LED panel 15 side. The polarizer is bonded to the surface of the retardation plate on the side opposite to the organic LED panel 15 side. Specifically, the polarizer is a linear polarizer, and the retardation plate is a λ / 4 retardation plate. The touch panel 30 includes a transparent glass plate and preferably employs a capacitive method. The cover glass 40 has a protective function and may also have other functions such as an anti-reflection function.

[0051] <Optical film> Hereinafter, the optical film 100 will be described in detail. The optical film 100 has a base material 101, a low refractive index layer 102, and a high refractive index layer 103. The base material 101, the low refractive index layer 102, and the high refractive index layer 103 are laminated in this order from the side where the viewer is located with respect to the display device 10 toward the organic LED panel 15 side. In other words, the base material 101, the low refractive index layer 102, and the high refractive index layer 103 are laminated in this order from the viewer side toward the inside of the device in the thickness direction Z.

[0052] The base material 101 is in the form of a film and is bonded to the low refractive index layer 102 on the back surface of the front and back surfaces. The base material 101 is a transparent base material having light transmissibility made of resin, glass, or the like.

[0053] The base material 101 is composed of, for example, polyethylene terephthalate, polyolefin, polycarbonate, polyacrylate, polyamide, a film mainly composed of triacetyl cellulose, glass, or the like.

[0054] The thickness of the base material 101 is, for example, 10 μm or more and 200 μm or less. The refractive index of the base material 101 is, for example, 1.46 or more and 1.67 or less. The main component means a component contained at a ratio of 50% or more with respect to the whole substance among a plurality of components constituting a certain substance or the most contained component. Further, the optical film 100 in the present embodiment includes the base material 101, but the optical film 100 may not have the base material 101.

[0055] FIG. 3 is a partial perspective view of the optical film 100, and more specifically, a partial perspective view of the low refractive index layer 102. FIG. 4 is a view of the low refractive index layer 102 seen in the direction of its normal, in other words, a view seen in the thickness direction Z. FIG. 4 schematically shows the arrangement of the lens portions 110 described later provided in the low refractive index layer 102. FIG. 5 is a cross-sectional view when the optical film 100 is cut along the line V-V in FIG. 4.

[0056] As shown in FIGS. 2 and 3, the low refractive index layer 102 integrally includes a film-shaped layer body 102A having a front surface and a back surface, and a plurality of lens portions 110 which are an example of optical elements two-dimensionally arranged along the first direction D1 and the second direction D2 on the back surface of the layer body 102A. As shown in FIG. 3, the lens portions 110 are arranged along the first direction D1 and the second direction D2 that obliquely intersect both in the left-right direction X and the up-down direction Y. FIG. 2 is a schematic cross-sectional view, and for convenience of explanation, the lens portions 110 are shown arranged in the left-right direction X. However, in reality, the lens portions 110 in the present embodiment are arranged along the first direction D1 and the second direction D2.

[0057] The first direction D1 and the second direction D2 are directions parallel to the film surface of the optical film 100 and intersecting each other. Also, the first direction D1 and the second direction D2 are respectively directions non-parallel to the four sides of the optical film 100. The plurality of lens portions 110 are arranged at intervals on each grid line of a grid pattern formed by a plurality of grid lines extending in each of the first direction D1 and the second direction D2. The grid lines mentioned here are virtual lines.

[0058] The high refractive index layer 103 is joined to the low refractive index layer 102 so as to cover the lens portions 110 and be filled up to between the plurality of lens portions 110. Thereby, in the present embodiment, the interface between the low refractive index layer 102 and the high refractive index layer 103 has an uneven shape. At this time, the high refractive index layer 103 has a film shape having a plurality of holes for accommodating the plurality of lens portions 110 and becomes at least partially grid-shaped.

[0059] Note that the low refractive index layer 102 may be composed of a collection of a plurality of lens portions 110 without having a layer main body 102A. Also, the optical film 100 may not include the high refractive index layer 103. Further, the low refractive index layer 102 may not be provided. That is, the low refractive index layer 102 may be formed of an air layer. In this case, the space surrounded by the lattice-like portion of the high refractive index layer 103 forms an optical element.

[0060] The refractive index of the low refractive index layer 102 is, for example, 1.40 or more and 1.55 or less. The refractive index of the high refractive index layer 103 is, for example, 1.55 or more and 1.90 or less, and is larger than the refractive index of the low refractive index layer 102. In the present embodiment, as an example, the low refractive index layer 102 and the high refractive index layer 103 are selected such that the difference between the refractive index of the low refractive index layer 102 and the refractive index of the high refractive index layer 103 is in the range of 0.05 or more and 0.50 or less.

[0061] Also, in the present embodiment, the high refractive index layer 103 of the low refractive index layer 102 and the high refractive index layer 103 is disposed closer to the organic LED panel 15 side than the low refractive index layer 102, but this arrangement order may be reversed.

[0062] The low refractive index layer 102 may be formed, for example, by curing an ultraviolet curable resin, an electron beam curable resin, or a thermosetting resin. When the low refractive index layer 102 is formed by curing an ultraviolet curable resin, the ultraviolet curable resin may contain an acrylic resin or may contain an epoxy resin.

[0063] Similarly, the high refractive index layer 103 may be formed, for example, by curing an ultraviolet curable resin, an electron beam curable resin, or a thermosetting resin. When the high refractive index layer 103 is formed by curing an ultraviolet curable resin, the ultraviolet curable resin may contain an acrylic resin or may contain an epoxy resin. Further, when the high refractive index layer 103 is formed as an adhesive layer, the high refractive index layer 103 may be formed of an acrylic resin adhesive.

[0064] Further, the dimension (thickness) in the thickness direction Z of the layer main body 102A in the low refractive index layer 102 is, for example, 0.5 μm or more and 30 μm or less. Also, the height of the lens portion 110 is, for example, 1.0 μm or more and 30 μm or less. On the other hand, the thickness of the high refractive index layer 103 is, for example, 5 μm or more and 100 μm or less.

[0065] Hereinafter, the configuration of the lens portion 110, which is an optical element, will be described in detail.

[0066] As shown in FIGS. 3 and 5, the lens portion 110 is, as an example, frustum-shaped. The lens portion 110 has a front end surface 110T parallel to the film surface and a side surface 110S located between the front end surface 110T and the base end on the opposite side thereof. The side surface 110S has a tapered shape toward the organic LED panel 15 side, which is one side in the normal direction of the film surface of the optical film 100.

[0067] As shown in FIG. 4, the side surface 110S has a pair of first element side surfaces 111, 111 facing each other and a pair of second element side surfaces 112, 112 facing each other in a direction orthogonal to the direction in which the pair of first element side surfaces 111, 111 face each other. The pair of first element side surfaces 111, 111 and the pair of second element side surfaces 112, 112 are each a flat surface. However, at least one of the pair of first element side surfaces 111, 111 and the pair of second element side surfaces 112, 112 may be a curved surface or a stepped surface. Also, the lens portion 110 may be, for example, pyramidal, octagonal pyramidal, frustum-shaped with eight sides, etc.

[0068] In FIG. 4, reference numerals N1 and N1 respectively indicate the normal directions of a pair of first element side surfaces 111 and 111. As is clear from FIG. 4, these normal directions N1 and N1 are each non-parallel to the plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and the plane including the second direction D2 and the normal direction of the film surface. On the other hand, the normal directions N1 and N1 are each parallel to the second side 100B of the optical film 100. In other words, the normal directions N1 and N1 are each parallel to the left-right direction X. Also, the flat first element side surfaces 111 and 111 are parallel to the first side 100A and the up-down direction Y. Further, the first element side surfaces 111 and 111 face each other in the direction in which the second side 100B extends, that is, in the left-right direction X.

[0069] Also, reference numerals N2 and N2 respectively indicate the normal directions of a pair of second element side surfaces 112 and 112. These normal directions N2 and N2 are also each non-parallel to the plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and the plane including the second direction D2 and the normal direction of the film surface. On the other hand, the normal directions N2 and N2 are each parallel to the first side 100A of the optical film 100. In other words, the normals N2 and N2 are each parallel to the up-down direction Y. Also, the flat second element side surfaces 112 and 112 are parallel to the second side 100B and the left-right direction X. Further, the second element side surfaces 112 and 112 face each other in the direction in which the first side 100A extends, that is, in the up-down direction Y. In the present embodiment, when viewed in the normal direction of the film surface, the normal directions N1 and N1 and the normal directions N2 and N2 are orthogonal to each other.

[0070] That is, in the present embodiment, the plurality of lens portions 110 are arranged along a lattice pattern formed by a plurality of lattice lines extending in a first direction D1 and a second direction D2 that obliquely intersect both in the left-right direction X and the up-down direction Y. On the other hand, the first element side surfaces 111, 111 and the second element side surfaces 112, 112 face either the left-right direction X or the up-down direction Y. The lens portion 110 diffuses and deflects most of the light emitted from the organic LED panel 15 along a plane including the normal directions N1, N1 and the normal direction of the film surface from the first element side surfaces 111, 111, and also diffuses and deflects it along a plane including the normal directions N2, N2 and the normal direction of the film surface from the second element side surfaces 112, 112. That is, while the lens portion 110 faces the surface (111, 112) where the optical function is effectively exhibited in the left-right direction X or the up-down direction Y, it inclines the first direction D1 and the second direction D2, which are its arrangement directions, with respect to the left-right direction X and the up-down direction Y.

[0071] Also, in the present embodiment, as shown in FIG. 4, among the plurality of lens portions 110, adjacent lens portions 110 are not arranged along a plane including the normal directions N1, N1 of the respective pair of first element side surfaces 111, 111 and the normal direction of the film surface. In other words, they are not linearly arranged in a direction parallel to the said plane. Also, among the plurality of lens portions 110, adjacent lens portions 110 are not arranged along a plane including the normal directions N2, N2 of the respective pair of second element side surfaces 112, 112 and the normal direction of the film surface. In other words, they are not linearly arranged in a direction parallel to the said plane.

[0072] Note that the pitch P1 of the lens units 110 arranged in the first direction D1 and the pitch P2 of the lens units 110 arranged in the second direction D2 are both equal pitches, that is, constant pitches, and have the same value as each other in the present embodiment. However, each pitch is not limited to an equal pitch. Also, as described above, at least one of the pair of first element side surfaces 111, 111 and the pair of second element side surfaces 112, 112 may be a curved surface or a stepped surface. Here, when the first element side surface 111 and / or the second element side surface 112 is a curved surface, it is sufficient that the normal direction determined at least at the center in the width direction of the curved surface is non-parallel to the plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and the plane including the second direction D2 and the normal direction of the film surface. Also, when the first element side surface 111 and / or the second element side surface 112 is a stepped surface, it is sufficient that the normal direction of the plane including the side on the tip side and the side on the base end side is non-parallel to the plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and the plane including the second direction D2 and the normal direction of the film surface.

[0073] Also, the configuration of the lens unit 110 as an optical element in the present embodiment will be described in another way while referring to FIG. 4 as follows. When a first reference line SL1 parallel to the film surface is extended horizontally from the first lens unit 110 (reference numeral 110-1) among the plurality of lens units 110, the second lens unit 110 (reference numeral 110-2) adjacent to the first lens unit 110 (reference numeral 110-1) is arranged at a predetermined interval in the direction forming a first angle θa with respect to the first reference line SL1 (that is, the first direction D1). The third lens unit 110 (reference numeral 110-3) adjacent to the first lens unit 110 (reference numeral 110-1) is arranged at a predetermined interval in the direction forming a second angle θb with respect to the second reference line SL2 orthogonal to the first reference line SL1 and parallel to the film surface (that is, the second direction D2). And the other lens units 110 among the plurality of lens units 110 are also arranged at a predetermined interval from the adjacent lens units 110 in the direction forming the first angle θa, and are arranged at a predetermined interval from the adjacent lens units 110 in the direction forming the second angle θb. In addition, in the present embodiment, the first reference line SL1 is parallel to the second side 100B of the optical film 100. The second reference line SL2 is parallel to the first side 100A of the optical film 100.

[0074] Then, the centers C of the respective lens portions 110 adjacent in the direction of the first reference SL1 line are not aligned on the first reference line SL1. Also, the centers C of the respective lens portions 110 adjacent in the direction of the second reference line SL2 are not aligned on the second reference line SL2. On the other hand, the centers C of the respective lens portions 110 adjacent in the direction forming the first angle θa are aligned in the direction forming the first angle θa, precisely, they are aligned on a straight line extending in the direction forming the first angle θa. Further, the centers C of the adjacent lens portions 110 in the direction forming the second angle θb are aligned in the direction forming the second angle θb, precisely, they are aligned on a straight line extending in the direction forming the second angle θb. Note that the center of the lens portion 110 is the center of the lens portion 110 when viewed in the normal direction of the film surface.

[0075] In addition, the lens portion 110 has sides parallel to the first reference line SL1 or the second reference line SL2. More specifically, the base-end side edge 111p and the tip-end side edge 111d of the first element side surface 111 on the side surface 110S of the lens portion 110 are parallel to the second reference line SL2. The base-end side edge 112p and the tip-end side edge 112d of the second element side surface 112 are parallel to the first reference line SL1. Then, when viewed in the normal direction of the film surface, the sides of the adjacent lens portions 110 facing each other in the direction forming the first angle θa are parallel to each other. That is, the edges 111p and 111d of one of the adjacent lens portions 110 facing each other are parallel to the edges 111p and 111d of the other lens portion 110. Also, when viewed in the normal direction of the film surface, the sides of the adjacent lens portions 110 facing each other in the direction forming the second angle θb are parallel to each other. That is, the edges 112p and 112d of one of the adjacent lens portions 110 facing each other are parallel to the edges 112p and 112d of the other lens portion 110.

[0076] Furthermore, the tangents of the base-end side edge 111p and the tip-end side edge 111d of the first element side surface 111 on the side surface 110S of the lens unit 110 are non-parallel to the direction forming the first angle θa (i.e., the first direction D1) and the direction forming the second angle θb (i.e., the second direction D2), and are parallel to the second reference line SL2. The tangents of the base-end side edge 112p and the tip-end side edge 112d of the second element side surface 112 are non-parallel to the direction forming the first angle θa (i.e., the first direction D1) and the direction forming the second angle θb (i.e., the second direction D2), and are parallel to the first reference line SL1. The above relationship also holds when the first element side surface 111 and the second element side surface 112 are curved surfaces.

[0077] Also, the direction passing through both ends of the first element side surface 111 in the direction parallel to the film surface (which coincides with the second direction D2 in this example) is non-parallel to the direction forming the first angle θa and the direction forming the second angle θb, and is non-parallel at an angle different from 45 degrees in this embodiment. Also, the direction passing through both ends of the second element side surface 112 in the direction parallel to the film surface (which coincides with the first direction D1 in this example) is non-parallel to the direction forming the first angle θa and the direction forming the second angle θb, and is non-parallel at an angle different from 45 degrees in this embodiment. Note that the first angle θa is preferably 5 degrees or more and 40 degrees or less. The second angle θb is preferably 5 degrees or more and 40 degrees or less.

[0078] FIG. 6A is a diagram showing a pixel arrangement of the organic LED panel 15. The organic LED panel 15 has a plurality of pixels 150 including a plurality of sub-pixels having different colors from each other. The plurality of pixels 1 50 are arranged at equal pitches, that is, at a constant pitch, on each grid line of a grid pattern formed by grid lines extending in the first pixel arrangement direction PD1 and the second pixel arrangement direction PD2 orthogonal to the first pixel arrangement direction PD1, respectively.

[0079] In the pixel 150 in the present embodiment, as an example, the sub-pixel arrangement is a diamond pentile arrangement among pentile arrangements. That is, the pixel 150 is composed of a set of a sub-pixel 150R that emits red light and a sub-pixel 150G that emits green light, or a set of a sub-pixel 150B that emits blue light and a sub-pixel 150G that emits green light. And a plurality of sub-pixels in one pixel 150 are arranged in a direction obliquely intersecting the first pixel arrangement direction PD1 and the second pixel arrangement direction PD2. Specifically, this obliquely intersecting direction is a direction forming a 45-degree angle with each of the first pixel arrangement direction PD1 and the second pixel arrangement direction PD2. And the pixel 150 of the set of the sub-pixel 150R that emits red light and the sub-pixel 150G that emits green light and the pixel 150 of the set of the sub-pixel 150B that emits blue light and the sub-pixel 150G that emits green light are alternately arranged. Note that there may be a case where one pixel is called a combination of 2 R sub-pixels, 2 B sub-pixels, and 4 G sub-pixels, but in the present embodiment, a combination of 1 R sub-pixel and 1 G sub-pixel, or a combination of 1 B sub-pixel and 1 G sub-pixel is called a pixel.

[0080] In the present embodiment, the first pixel arrangement direction PD1 coincides with the left-right direction X, and the second pixel arrangement direction PD2 coincides with the up-down direction Y. Therefore, the first direction D1 and the second direction D2, which are the arrangement directions of the lens unit 110, are non-parallel to the first pixel arrangement direction PD1 and the second pixel arrangement direction PD2, respectively. Further, in the present embodiment, the first direction D1 and the second direction D2 are also non-parallel to the direction in which a plurality of sub-pixels are arranged in the pixel 150. And when viewed from the normal direction of the film surface of the optical film 100, the normal directions N1, N1 of the pair of first element side surfaces 111, 111 are parallel to the first pixel arrangement direction PD1, and the normal directions N2, N2 of the pair of second element side surfaces 112, 112 are parallel to the second pixel arrangement direction PD2.

[0081] That is, the lens unit 110 faces the surfaces (111, 112) where the optical function is effectively exerted in the first pixel array direction PD1 or the second pixel array direction PD2, while tilting its array direction with respect to the first pixel array direction PD1 and the second pixel array direction PD2. Further, in the present embodiment, the array direction of the lens unit 110 is also tilted with respect to the direction in which the sub-pixels arranged obliquely intersecting the first pixel array direction PD1 and the second pixel array direction PD2 are arranged. In the present embodiment, by adopting these configurations, the optical function by the lens unit 110 is effectively exerted in the first pixel array direction PD1 and the second pixel array direction PD2. At the same time, the lattice pattern formed by the arrangement of the plurality of lens units 110 is tilted with respect to the lattice pattern formed by the pixels 150 and the lattice pattern formed by the sub-pixels 150R, G, B, so that moiré is reduced or becomes less noticeable. Note that the arrangement of the sub-pixels in the pixel 150 is not particularly limited, and may be a stripe arrangement as shown in FIG. 6B.

[0082] Hereinafter, the orientation and dimensional conditions of the lens unit 110 will be described. In FIG. 4, reference sign θ1 indicates the angle formed by the direction parallel to the plane including the normal directions N1, N1 of the pair of first element side surfaces 111, 111 and the normal direction of the film surface and the first direction D1. Reference sign θ2 indicates the angle formed by the direction parallel to the plane including the normal directions N2, N2 of the pair of second element side surfaces 112, 112 and the normal direction of the film surface and the first direction D1.

[0083] The angle θ1 and the angle θ2 are each preferably 5 degrees or more and 40 degrees or less, particularly preferably 10 degrees or more and 40 degrees or less, or 50 degrees or more and 85 degrees or less, particularly preferably 50 degrees or more and 80 degrees or less. More specifically, it is preferable that the angle θ1 is 5 degrees or more and 40 degrees or less, and the angle θ2 is 50 degrees or more and 85 degrees or less, or the angle θ1 is 50 degrees or more and 85 degrees or less, and the angle θ2 is 5 degrees or more and 40 degrees or less. More preferably, the angle θ1 is 10 degrees or more and 40 degrees or less, and the angle θ2 is 50 degrees or more and 80 degrees or less, or the angle θ1 is 50 degrees or more and 80 degrees or less, and the angle θ2 is 10 degrees or more and 40 degrees or less.

[0084] In this embodiment, the preferred ranges of the above-described angle θ1 and angle θ2 have the following meanings. Preferably, the first direction D1 forms an angle of 5 degrees or more and 40 degrees or less, or 50 degrees or more and 85 degrees or less with the left-right direction X and the first pixel array direction PD1, and more preferably forms an angle of 10 degrees or more and 40 degrees or less, or 50 degrees or more and 80 degrees or less. Preferably, the second direction D2 forms an angle of 5 degrees or more and 40 degrees or less, or 50 degrees or more and 85 degrees or less with the left-right direction X and the first pixel array direction PD1, and more preferably forms an angle of 10 degrees or more and 40 degrees or less, or 50 degrees or more and 80 degrees or less.

[0085] When the angle formed by the first direction D1 with the left-right direction X and the first pixel array direction PD1 and the angle formed by the second direction D2 with the left-right direction X and the first pixel array direction PD1 are the above-described conditions, moiré is effectively reduced or becomes less noticeable. Note that, the closer the angle formed by the first direction D1 with the left-right direction X and the first pixel array direction PD1 is to 0 degrees or 45 degrees, the more the moiré reduction effect tends to decrease. That is, in this case, since the overlapping state of the pixel array and the optical element array hardly changes between adjacent sub-pixels, moiré tends to increase. From such a viewpoint, the above-described angle range can be said to be a preferred range.

[0086] Hereinafter, the general term for the angle formed by the first direction D1 with the left-right direction X and the first pixel array direction PD1 and the angle formed by the second direction D2 with the left-right direction X and the first pixel array direction PD1 is referred to as a bias angle. Here, the bias angle at which a preferable moiré reduction effect can be obtained can be selected, for example, by calculating the value at which moiré is minimized. Such a selection can be performed, for example, by the following procedure (Steps 1 to 7).

[0087] (Step 1) First, the organic LED panel 15 and the optical film 100 are overlapped at a certain bias angle. (Step 2) Next, the amount of luminance reduction of any one sub-pixel in any one of the plurality of pixels 150 is calculated. At this time, the front end surface 110T of the lens unit 110 is treated as transparent (light transmission state), and the side surface 110S is treated as shielded (light non-transmission state). That is, the amount of luminance reduction is calculated based on the ratio of the area within the sub-pixel shielded by the side surface 110S. (Step 3) Next, the amount of luminance reduction of the remaining sub-pixels in the pixel 150 including the sub-pixel whose luminance reduction amount was calculated in the second step is calculated by the same method as in the second step. In the present embodiment, since there is one remaining sub-pixel in the pixel 150, after the amount of luminance reduction for this is calculated, the third step ends. On the other hand, for example, when it is a stripe arrangement, there are two remaining sub-pixels in the pixel 150. In this case, after calculating the amount of luminance reduction for one of the remaining sub-pixels, the amount of luminance reduction for the other is calculated. (Step 4) Next, for all the other pixels 150 among the plurality of pixels 150, the second step and the third step are performed to specify the amount of luminance reduction of each sub-pixel in all the pixels 150. Then, based on the information on the amount of luminance reduction in all such pixels 150, a moiré image indicating luminance unevenness for each color sub-pixel is formed. (Step 5) Next, the maximum luminance and the minimum luminance in the moiré image for each sub-pixel are specified based on the amount of luminance reduction, and the luminance unevenness (referred to as single-color luminance unevenness) in each sub-pixel is calculated, for example, by the following formula. Single-color luminance unevenness = (maximum luminance - minimum luminance) / (maximum luminance + minimum luminance) (Step 6) Next, the average value of the single-color luminance unevenness of each sub-pixel is calculated and specified as a representative value of the luminance unevenness. (Step 7) Then, the bias angle is sequentially changed, and by performing the second to sixth steps, representative values of luminance unevenness for a plurality of bias angles are specified. And a bias angle at which a moiré reduction effect can be preferably obtained is selected based on the plurality of representative values of luminance unevenness.

[0088] Return to FIG. 4 for the description of other dimensions. Reference numeral P1 indicates the pitch of the lens unit 110 in the first direction D1. Reference numeral P2 indicates the pitch of the lens unit 110 in the second direction D2. The pitch P1 is, for example, 2 μm or more and 50 μm or less. The pitch P2 is, for example, 2 μm or more and 50 μm or less. In the present embodiment, the pitch P1 and the pitch P2 are constant values and are the same as each other. However, the pitch P1 and the pitch P2 may not be the same value.

[0089] In FIG. 5, reference numeral H indicates the height of the lens unit 110 in the thickness direction Z. The height of the lens unit 110 is, for example, 1 μm or more and 30 μm or less. Reference numeral Wex indicates the outer frame width which is the width between both ends of the lens unit 110 in the left - right direction X. The outer frame width Wex is, for example, 2 μm or more and 40 μm or less. Reference numeral Wit indicates the intermediate width which is the dimension between a pair of first element side surfaces 111, 111 at the center in the height direction of the lens unit 110. The intermediate width Wit is smaller than the outer frame width Wex and is, for example, 2 μm or more and 40 μm or less. Reference numeral Wsi indicates the side surface width which is the dimension of one first element side surface 111 in the left - right direction X. The side surface width Wsi is, for example, 0.2 μm or more and 4 μm or less. Reference numeral θ R indicates the inclination angle of the first element side surface 111. The inclination angle θ R is, for example, 2 degrees or more and 30 degrees or less. Note that the lens unit 110 in the present embodiment has a frustum - of - regular - square - pyramid shape. Therefore, the outer frame width, the intermediate width, the side surface width, and the inclination angle in the up - down direction Y are the same as those in the left - right direction X.

[0090] In the present embodiment, the optical elements 110 adjacent in the first direction D1 are adjacent to each other with a gap, in other words, a predetermined interval, in the direction in which a pair of first sides 100A, 100A face each other. And a pair of first element side surfaces 111, 111 each face the gap in the direction in which the pair of first sides 100A, 100A face each other. Then, the first duty D1 is defined by dividing the intermediate width Wit of the pair of first element side surfaces 111, 111 by the pitch P1 of the lens portion 110 in the first direction D1. Also, the optical elements 110 adjacent in the second direction D2 are adjacent to each other with a gap, in other words, a predetermined interval, in the direction in which a pair of second sides 100B, 100B face each other. And a pair of second element side surfaces 112, 112 each face the gap in the direction in which the pair of second sides 100B, 100B face each other. Then, the second duty D2 is defined by dividing the intermediate width of the pair of second element side surfaces 112, 112 by the pitch P2 of the lens portion 110 in the second direction D2. Here, it is preferable that these first duty D1 and second duty D2 are each 0.5 or more and 0.8 or less.

[0091] Note that, for example, the optical elements 110 adjacent in the first direction D1 may have a gap in each of the direction in which a pair of first sides 100A, 100A face each other and the direction in which a pair of second sides 100B, 100B face each other. In this case, the first duty D1 has two types: one obtained by dividing the intermediate width of the pair of first element side surfaces 111, 111 by the pitch P1, and the other obtained by dividing the intermediate width of the pair of second element side surfaces 112, 112 by the pitch P1. In this case, it is preferable that both are 0.5 or more and 0.8 or less. This is the same for the second duty D2.

[0092] When the first duty D1 and the second duty D2 are less than 0.5, it tends to be difficult to exhibit the moiré reduction effect by shifting, that is, biasing, the lattice pattern. Further, when the first duty D1 and the second duty D2 are greater than 0.8, moiré tends to increase due to the adjacent lens portions 110 approaching each other excessively. When the adjacent lens portions 110 approach each other excessively, the in-plane unevenness of the portion shielded by the side surface 110S of the lens portion 110 in the subpixel tends to increase, and it is presumed that moiré tends to increase due to this.

[0093] In addition, the symbol Wp in FIG. 6A indicates the minimum width in the plan view of the subpixel in the pixel 150. In this example, the green subpixel 150G is smaller than the other subpixels. Therefore, the width Wp is the minimum width of the subpixel 150G. Here, it is preferable that the pitch P1 of the lens portion 110 in the first direction D1 and the pitch P2 of the lens portion 110 in the second direction D2 are each less than or equal to half of the width Wp of the subpixel. This is because when there is only about one lens portion 110 located in one subpixel, it tends to be difficult to exhibit the moiré reduction effect by biasing.

[0094] <Operation> Next, the operation of the display device 10 according to the present embodiment will be described.

[0095] Referring to FIG. 2, when light for image formation is emitted from the organic LED panel 15, the light passes through the circular polarizing plate 20, the touch panel 30, and the cover glass 40 and enters the optical film 100. Among the light incident on the optical film 100, the light traveling toward the front end surface 110T of the lens portion 110 or the flat portion of the layer main body 102A between the adjacent lens portions 110 along the front view direction is emitted from the low refractive index layer 102 without changing or hardly changing the angle of the traveling direction, and does not affect the optical characteristics.

[0096] On the one hand, the light among the light incident on the optical film 100 that travels toward the side surface 110S of the lens unit 110 is diffused over a wide range. At this time, in this example, the light on the high-angle side and the light on the low-angle side are exchanged. As a result, the blue shift is reduced. Also, in another design, a part of the diffused light moves to the high-angle side. This avoids the concentration of a large amount of light in the front view direction, and a high-brightness display image can be visually recognized even in an oblique viewing direction.

[0097] Here, the lens unit 110 has a pair of first element side surfaces 111, 111 and a pair of second element side surfaces 112, 112 as surfaces on which the optical function is effectively exerted. The first element side surfaces 111, 111 face the first pixel array direction PD1, and the second element side surfaces 112, 112 face the second pixel array direction PD2. As a result, the optical function by the lens unit 110 effectively occurs in the first pixel array direction PD1 and the second pixel array direction PD2. As a result, the display quality in the first pixel array direction PD1 and the second pixel array direction PD2 in the display image is good, and particularly the color tone in the oblique viewing direction in the plane including the first pixel array direction PD1 and the normal direction of the film surface and the plane including the second pixel array direction PD2 and the normal direction of the film surface is good.

[0098] The pair of first element side surfaces 111, 111 are symmetric with respect to the axis along the second pixel array direction PD2. The pair of second element side surfaces 112, 112 are symmetric with respect to the axis along the first pixel array direction PD1. Therefore, in the optical characteristics of the display image, axial symmetry is ensured with respect to each axis of the first pixel array direction PD1 and the second pixel array direction PD2.

[0099] In addition, the first direction D1 and the second direction D2, which are the arrangement directions of the lens units 110, are inclined with respect to the first pixel arrangement direction PD1 or the second pixel arrangement direction PD2. Further, in the present embodiment, the first direction D1 and the second direction D2 are also inclined with respect to the direction in which sub-pixels that intersect obliquely with the first pixel arrangement direction PD1 and the second pixel arrangement direction PD2 are arranged. As a result, the lattice pattern formed by the arrangement of the plurality of lens units 110 is inclined with respect to the lattice pattern formed by the pixels 150 and the lattice pattern formed by the sub-pixels 150R, G, B. Thereby, moiré is effectively reduced or made less noticeable.

[0100] As described above, in the present embodiment, when displaying a display image by transmitting the light emitted from the pixels 150, while ensuring optical characteristics having axial symmetry with respect to at least one (both in the present embodiment) of two axes orthogonal to each other that serve as the reference of the pixel array in the display image, it is possible to suppress a decrease in the visibility of the display image due to moiré.

[0101] Hereinafter, modifications of the above-described embodiment will be described. FIGS. 7 to 10 show modifications of the above-described embodiment. The same components as those described in the above-described embodiment among the components in each modification are denoted by the same reference numerals, and descriptions other than the differences are omitted.

[0102] <Modification> The display device 10' with an optical film according to the modification shown in FIG. 7 is configured by laminating an organic LED panel 15, an optical film 100, a circular polarizing plate 20, a touch panel 30, and a cover glass 40 in this order. That is, in this modification, the position of the optical film 100 is different from that in the above-described embodiment. In the above-described embodiment and the modification of FIG. 7, the display panel is an organic LED panel, but the display panel may also be a liquid crystal panel. The lens portions 110 shown in FIG. 7 are arranged along a first direction D1 and a second direction D2 that obliquely intersect both in the left-right direction X and the up-down direction Y, similar to the above-described embodiment. FIG. 7 is a schematic cross-sectional view, and for convenience of explanation, the lens portions 110 are shown arranged in the left-right direction X. However, in reality, the lens portions 110 in the present embodiment are arranged along the first direction D1 and the second direction D2.

[0103] In the modification shown in FIG. 8, rounded corners R are provided at the four corners formed by the first element side surface 111 and the second element side surface 112 of the frustum-of-a-square-pyramid-shaped lens portion 110. In other words, rounded corners R are provided on the ridge lines of the side surface 110S of the lens portion 110. A form such as FIG. 8 may also be used as a modification of the embodiment shown in FIG. 4 and the like. In the configuration of FIG. 8, the portion located between the rounded corners R at both ends on the first element side surface 111 is non-parallel to the plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and the plane including the second direction D2 and the normal direction of the film surface. The portion located between the rounded corners R at both ends on the second element side surface 112 is non-parallel to the plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and the plane including the second direction D2 and the normal direction of the film surface. On the one hand, referring to FIGS. 4 and 8, the normal directions N1, N1 of the portions located between the rounded portions R at both ends on the first element side surface 111 are each parallel to the second side 100B of the optical film 100. In other words, the normal directions N1, N1 are each parallel to the left-right direction X. Further, the portions located between the rounded portions R at both ends on the first element side surface 111, which is a flat surface, are parallel to the first side 100A and the up-down direction Y. Also, the first element side surfaces 111, 111 face each other in the direction in which the second side 100B extends, that is, in the left-right direction X. Furthermore, the normal directions N2, N2 of the portions located between the rounded portions R at both ends on the second element side surface 112 are each parallel to the first side 100A of the optical film 100. In other words, the normal directions N2, N2 are each parallel to the up-down direction Y. Also, the portions located between the rounded portions R at both ends on the second element side surface 112, which is a flat surface, are parallel to the second side 100B and the left-right direction X. Also, the second element side surfaces 112, 112 face each other in the direction in which the first side 100A extends, that is, in the up-down direction Y.

[0104] In the modification shown in FIG. 9, instead of the lens portion 110 in the above-described embodiment, an optical element 120 made of a diffraction grating is employed. The optical element 120 has a first element 121 and a second element 122. Referring also to FIG. 1, the first element 121 is a diffraction grating having a plurality of grooves 121g that are recessed on one side or the other side in the normal direction of the film surface of the optical film 100 and are elongated in a direction parallel to the first side 100A of the optical film 100. In each groove 121g, the normal directions of the first element side surfaces 111, 111 formed in each groove 121g are non-parallel to the plane including the first direction D1 and the normal direction of the film surface and the plane including the second direction D2 and the normal direction of the film surface. In each groove 121g, a side surface 110S is formed between the recess start edge and the bottom end. The recess start edge means the portion where the groove 121g starts to be recessed with respect to the outermost surface of the low refractive index layer 102 or the high refractive index layer 103. The first element side surfaces 111, 111 formed in each groove 121g are non-parallel to the plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and the plane including the second direction D2 and the normal direction of the film surface. Referring to FIGS. 4 and 9, the normal directions of the first element side surfaces 111, 111 formed in each groove 121g are parallel to the second side 100B of the optical film 100. In other words, these normal directions are each parallel to the left-right direction X. Further, the first element side surface 111, which is a flat surface, is parallel to the first side 100A and the up-down direction Y. Further, the first element side surfaces 111, 111 face each other in the direction in which the second side 100B extends, that is, in the left-right direction X. Further, the second element 122 is a diffraction grating having a plurality of grooves 122g that are recessed on one side or the other side in the normal direction of the film surface of the optical film 100 and are elongated in a direction parallel to the second side 100B. The normal directions of the second element side surfaces 112, 112 formed in each groove 122g are non-parallel to the plane including the first direction D1 and the normal direction of the film surface and the plane including the second direction D2 and the normal direction of the film surface. In each groove 122g, a side surface 110S is formed between the recess start edge and the bottom end. The second element side surfaces 112, 112 formed in each groove 122g are non-parallel to the plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and the plane including the second direction D2 and the normal direction of the film surface. Referring to FIGS. 4 and 9, the normal directions of the second element side surfaces 112, 112 formed in each groove 122g are parallel to the first side 100A of the optical film 100. In other words, these normal directions are each parallel to the vertical direction Y. Further, the second element side surface 112 which is a flat surface is parallel to the second side 100B and the left-right direction X. Also, the second element side surfaces 112, 112 face each other in the direction in which the first side 100A extends, that is, in the vertical direction Y. And in each of the first direction D1 and the second direction D2, the first element 121 and the second element 122 are arranged in a mixed manner. Here, the first element 121 and the second element 122 are preferably arranged alternately. In the modification example of FIG. 9, the normal directions of the second element side surfaces 112, 112 in the first element 121 may or may not be non-parallel to the plane including the first direction D1 and the normal direction of the film surface and the plane including the second direction D2 and the normal direction of the film surface. Also, the normal directions of the first element side surfaces 111, 111 in the second element 122 may or may not be non-parallel to the plane including the first direction D1 and the normal direction of the film surface and the plane including the second direction D2 and the normal direction of the film surface.

[0105] In the modification of FIG. 10, instead of the lens unit 110, a recess formed in the low refractive index layer 102 forms the optical element 110'. In FIG. 10, (A) is a view of the optical element 110' seen in the thickness direction Z, and (B) is a cross-sectional view taken along the line XB-XB in FIG. 10(A). FIG. 10(C) is a perspective view looking down on the high refractive index layer 103. In the modification shown in FIG. 10, the optical element 110' is formed by a recess recessed in an irregular pyramid shape. A side surface 110S of the optical element 110' is formed between the recess start edge and the bottom end of the recess. Among the side surfaces 110S, the first element side surfaces 111, 111 face the left-right direction X, and their normal directions N1, N1 are parallel to the left-right direction X. Among the side surfaces 110S, the second element side surfaces 112, 112 face the up-down direction Y, and their normal directions N2, N2 are parallel to the up-down direction Y. The first element side surface 111 is non-parallel to a plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and a plane including the second direction D2 and the normal direction of the film surface. The second element side surface 112 is non-parallel to a plane including the first direction D1 and the normal direction of the film surface of the optical film 100 and a plane including the second direction D2 and the normal direction of the film surface. On the other hand, referring to FIGS. 4 and 10(A), the normal directions N1, N1 of the first element side surfaces 111 are each parallel to the second side 100B of the optical film 100. In other words, the normal directions N1, N1 are each parallel to the left-right direction X. Also, the first element side surface 111, which is a flat surface, is parallel to the first side 100A and the up-down direction Y. Further, the first element side surfaces 111, 111 face each other in the direction in which the second side 100B extends, that is, in the left-right direction X. Furthermore, the normal directions N2, N2 of the second element side surfaces 112 are each parallel to the first side 100A of the optical film 100. In other words, the normal directions N2, N2 are each parallel to the up-down direction Y. Also, the second element side surface 112, which is a flat surface, is parallel to the second side 100B and the left-right direction X. Further, the second element side surfaces 112, 112 face each other in the direction in which the first side 100A extends, that is, in the up-down direction Y. As shown in FIG. 10(C), the high refractive index layer 103 is provided with a plurality of pyramid-shaped convex portions embedded in the concave optical element 110'. The four surfaces of the convex portion having a square pyramid shape have two surfaces having a normal line coinciding with the normal line N1 and two surfaces having a normal line coinciding with the normal line N2. In FIG. 10(C), for the sake of convenience of explanation, the normal lines N1 and N2 are shown in a state of being projected onto the film surface. The convex portions of the high refractive index layer 103 are arranged at a predetermined pitch in the first direction D1 and are also arranged at a predetermined pitch in the second direction D2. As is apparent from the drawing, the normal line coinciding with the normal line N1 and the normal line coinciding with the normal line N2 of the convex portion of the high refractive index layer 103 are non-parallel to the first direction D1 and the second direction D2. In this example, both ends of the base end side of each of the two surfaces having a normal line coinciding with the normal line N1 in the convex portion of the high refractive index layer 103 are displaced in the direction of the normal line N1 when the normal line N1 is projected onto the film surface. And the adjacent convex portions of the high refractive index layer 103 are positioned in a state where the base end side sides facing each other are parallel. Thereby, the convex portions of the high refractive index layer 103 are arranged in the first direction D1 different from the direction of the normal line N1 when the normal line N1 is projected onto the film surface. The convex portions of the high refractive index layer 103 arranged in the second direction D2 are also arranged in the same arrangement mode as the convex portions arranged in the first direction D1 although the directions are different. Therefore, both ends of the side on the concave start edge side of the first element side surfaces 111, 111 of the optical element 110' are displaced in the direction of the normal line N1 when the normal line N1 is projected onto the film surface, that is, in the left-right direction X. And the adjacent optical elements 110' are positioned in a state where the base end side sides facing each other are parallel. Thereby, the optical elements 110' are arranged in the first direction D1 different from the direction of the normal line N1 when the normal line N1 is projected onto the film surface, that is, the left-right direction X. The optical elements 110' arranged in the second direction D2 are also arranged in the same arrangement mode as the optical elements 110' arranged in the first direction D1 although the directions are different.

Example

[0106] Next, Examples 1 to 3 of the present disclosure and Comparative Examples 1-1 to 1-3, 2-1 to 2-3 thereof will be described.

[0107] (Conditions such as dimensions and arrangements) In Examples 1 to 3 of the present disclosure, an optical film 100 having a lens portion 110 with a shape according to the dimensions shown in Table 1 below was created (see also FIGS. 4 and 5). Then, a display device 10 was configured by stacking each optical film 100 on a pixel 150 of the organic LED panel 15 at a bias angle θ1 shown in Table 1.

[0108] [Table 1]

[0109] Comparative Examples 1-1 to 1-3 each include an optical film having a lens portion with the same dimensions as the lens portion 110 according to Examples 1 to 3, and the lens portions are arranged along a grid pattern composed of grid lines parallel to the left-right direction X and the up-down direction Y. That is, in Comparative Examples 1-1 to 1-3, there is no bias angle. Also, Comparative Examples 2-1 to 2-3 each include an optical film having a lens portion with the same dimensions as the lens portion 110 according to Examples 1 to 3, and the lens portions are arranged in the same direction as the arrangement direction of the lens portions 110 in Examples 1 to 3, but the four side surfaces are inclined with respect to the left-right direction X and the up-down direction Y (parallel to the direction of the bias angle). Also, the organic LED panel in the comparative example is the same as the organic LED panel 15 in the example.

[0110] FIG. 11 is a diagram showing the arrangement of the lens portions and the arrangement of the sub-pixels in the example and the comparative example. FIG. 11(A) shows the arrangement of the lens portions 110 and the arrangement of the sub-pixels in Examples 1 to 3. FIG. 11(B) shows the arrangement of the lens portions and the arrangement of the sub-pixels in Comparative Examples 1-1 to 1-3. FIG. 11(C) shows the arrangement of the lens portions and the arrangement of the sub-pixels in Comparative Examples 2-1 to 2-3.

[0111] In Examples 1 to 3, the material of the lens unit 110 (low refractive index layer 102) is an acrylic-based ultraviolet curable resin, and its refractive index is 1.48. The lens unit (low refractive index layer) according to the comparative example is formed of the same material as that of the example. Referring to FIG. 6A, in the first pixel array direction PD1 of the organic LED panel 15 in the example, the pitch PP1 of the pixel 150 is 55.5 μm, and in the second pixel array direction PD2, the pitch PP2 of the pixel 150 is 55.5 μm. The width Wp of the green sub-pixel 150G is 15.8 μm. In the diamond pentile array as shown in this figure, two R sub-pixels, two B sub-pixels, and four G sub-pixels form a unit. Here, a combination of one R sub-pixel and one G sub-pixel, or a combination of one B sub-pixel and one G sub-pixel is referred to as a pixel.

[0112] (Evaluation Method) In evaluating the examples and the comparative example, a white image was displayed in each of the examples and the comparative example, and the color coordinates x and y in all directions were measured. The color coordinates x and y are the color coordinates x and y defined in the CIE1931 color space (CIE xyY color space). The measurement of the color coordinates x and y was performed using a color luminance system BM-7 manufactured by Topcon Corporation.

[0113] In addition, in order to evaluate the color change when viewed from the front view and the diagonal direction, the color coordinates x and y in the front view (0 degrees) and the color coordinates x and y when viewed from a direction inclined 45 degrees to the right in the left-right direction X with respect to the front view were specified. Then, the specified color coordinates x and y were converted into the color coordinates u' and v' in the uniform color space. The color coordinates u' and v' were calculated from the following equations (1-1) and (1-2), respectively.

[0114]

Equation

[0115] In addition, the color change Δu’v’ of the light emitted in the direction forming a 45-degree angle with respect to the color of the light emitted in the front view direction was calculated from the respective color coordinates u’ and v’. The color change Δu’v’ indicates the difference in color, and the smaller the value, the smaller the difference between the color of the light emitted in the front view direction and the color of the light at 45 degrees. The value of Δu’v’ at the angle θ in the viewing angle is represented by the following formula (2). By substituting the values of 0 degrees and 45 degrees for θ in formula (2), the color change at a viewing angle of 45 degrees can be obtained.

[0116] [Number]

[0117] In addition, in order to evaluate the strength of moiré, the numerical values of luminance unevenness were calculated for each of the examples and comparative examples. The calculation of luminance unevenness was performed according to the above-described second to sixth steps. The smaller the value of luminance unevenness, the greater the reduction level of moiré.

[0118] In addition, in each of the examples and comparative examples, based on the angular distribution of the color coordinates x and y specified in all directions, the axial symmetry of the display image with respect to the vertical axis and the horizontal axis was visually evaluated. In Examples 1 to 3 and Comparative Examples 1-1 to 1-3, since the four side surfaces of the lens portion face the horizontal direction or the vertical direction, the axial symmetry of the display image with respect to the vertical axis and the horizontal axis is ensured. On the other hand, in Examples 2-1 to 2-3, since the four side surfaces of the lens portion do not face the horizontal direction or the vertical direction, the axial symmetry of the display image with respect to the vertical axis and the horizontal axis is not ensured as compared with Examples 1 to 3. In the evaluation results of axial symmetry in Tables 2 to 4 below, "○" is indicated when the axial symmetry of the display image with respect to the vertical axis and the horizontal axis is ensured, and "×" is indicated when it is not.

[0119] The values of the color coordinates x and y at 0 degrees and 45 degrees, the color coordinates u’ and v’ at 0 degrees and 45 degrees, the color change Δu’v’, and the luminance unevenness, as well as the evaluation results of the axial symmetry of the optical characteristics, for Example 1, Comparative Example 1-1, and Comparative Example 2-1 are shown in Table 2 below.

[0120]

Table 2

[0121] The color coordinates x, y at 0° and 45°, the color coordinates u’, v’ at 0° and 45°, the color change Δu’v’, the value of luminance unevenness, and the evaluation results of the axial symmetry of the optical characteristics for each of Example 2, Comparative Example 1-2, and Comparative Example 2-2 are shown in Table 3 below.

[0122]

Table 3

[0123] The color coordinates x, y at 0° and 45°, the color coordinates u’, v’ at 0° and 45°, the color change Δu’v’, the value of luminance unevenness, and the evaluation results of the axial symmetry of the optical characteristics for each of Example 3, Comparative Example 1-3, and Comparative Example 2-3 are shown in Table 4 below.

[0124]

Table 4

[0125] When comparing Example 1, Comparative Example 1-1, and Comparative Example 2-1, the color change Δu’v’ of Example 1 is equivalent to those of Comparative Example 1-1 and Comparative Example 2-1, and both are suppressed to be lower than the value 0.01617 when there is no optical film. The luminance unevenness of Example 1 is suppressed more than that of Comparative Example 1-1. Also, the luminance unevenness of Example 1 is equivalent to that of Comparative Example 2-1. On the other hand, in Example 1, the axial symmetry of the optical characteristics of the display image can be ensured, while in Comparative Example 2-1, it cannot be ensured. Therefore, Example 1 is more advantageous than Comparative Example 1-1 and Comparative Example 2-1 when suppressing color change and moiré while ensuring the axial symmetry of the optical characteristics. The same can be said for the comparison of Example 2, Comparative Example 1-2, and Comparative Example 2-2, as well as the comparison of Example 3, Comparative Example 1-3, and Comparative Example 2-3.

[0126] From the evaluation results of the above embodiments as well, the effectiveness of this embodiment was confirmed. Note that the comparative examples do not mean the prior art and are not necessarily excluded from the invention.

Claims

1. An optical film comprising a plurality of optical elements, when a first reference line parallel to a film surface is extended horizontally from a first optical element of the plurality of optical elements, a second optical element adjacent to the first optical element is disposed at a predetermined interval in a direction that forms a first angle of 5 degrees or more and 40 degrees or less with respect to the first reference line, and a third optical element adjacent to the first optical element is disposed at a predetermined interval in a direction that forms a second angle of 5 degrees or more and 40 degrees or less with respect to a second reference line that is perpendicular to the first reference line and parallel to the film surface and that intersects with the direction of the first angle, Other optical elements among the plurality of optical elements are also arranged at a predetermined interval from adjacent optical elements in the direction forming the first angle, and are arranged at a predetermined interval from adjacent optical elements in the direction forming the second angle, Each of the optical elements has a truncated quadrangular pyramid shape that tapers toward one side or the other side in the normal direction of the film surface and has a side surface between a tip end and a base end, or has a truncated quadrangular pyramid shape that tapers toward one side or the other side in the normal direction of the film surface and has a side surface between a start edge of the depression and a bottom end, a tip surface of the optical element is parallel to the film surface; the side surfaces include a pair of first element side surfaces facing each other and a pair of second element side surfaces facing each other in a direction perpendicular to a direction in which the pair of first element side surfaces face each other, the pair of first element side surfaces are parallel to the first reference line, and the pair of second element side surfaces are parallel to the second reference line; The optical elements adjacent to each other in the direction forming the first angle are adjacent to each other with a first gap in either a direction in which the pair of first element side surfaces face each other or a direction in which the pair of second element side surfaces face each other, An optical film, wherein the optical elements adjacent in the direction forming the second angle are adjacent to each other with a second gap in either the direction in which the pair of first element side surfaces face each other or the direction in which the pair of second element side surfaces face each other.

2. a display panel in which a plurality of pixels are arranged in a first pixel arrangement direction and a second pixel arrangement direction perpendicular to the first pixel arrangement direction; The optical film according to claim 1 , the optical film is disposed on the plurality of pixels such that a direction forming the first angle, which is an arrangement direction of the optical elements, or the first direction and a direction forming the second angle, or the second direction, are non-parallel to the first pixel arrangement direction and the second pixel arrangement direction, respectively; A display device, wherein, when viewed in the normal direction of the film surface of the optical film, the normal direction of each of the pair of first element side surfaces is parallel to the first pixel array direction, and the normal direction of each of the pair of second element side surfaces is parallel to the second pixel array direction.

3. The display device according to claim 2 , wherein the display panel is an organic LED panel or a liquid crystal panel.

4. The display device according to claim 3 , wherein the arrangement of the sub-pixels in the pixel is a Pentile arrangement.

5. 5. The method of claim 4, wherein the pitch of the optical elements is less than or equal to half the width of the subpixels. Display device.

Images