JP2021018412A - Optical structure, polarizing plate with optical structure and display device - Google Patents

Abstract

To provide an optical structure for obtaining good display quality locally in a given angle range on a higher angle side within a viewing angle of a display device, while maintaining good display quality in a frontal view of the display device.SOLUTION: An optical structure 100 includes a low refractive index layer 102 and a high refractive index layer 103. An interface between the low refractive index layer 102 and the high refractive index layer 103 has a rugged pattern, in which a recess 121 in the rugged pattern is concave on the low refractive index layer 102 side, a projection 122 is convex on the high refractive index layer 103 side, and each of the recess 121 and the projection 122 has a flat portion extending in a plane direction of the low refractive index layer 102 and the high refractive index layer 103. In side faces 120S of the rugged pattern, two side faces 120S adjoining to each other and interposing the flat portion of the recess 121 form a tapered shape toward the low refractive index layer side; and two side faces 120S adjoining to each other and interposing the flat portion 122A of the projection 122 form a tapered shape toward the high refractive index layer side. The optical structure is disposed in such a manner that the high refractive index layer 103 faces a display screen side of a display device.SELECTED DRAWING: Figure 3

Description

The present invention relates to an optical structure that exerts an optical effect on light emitted from a display surface of a display device. The present invention also relates to a polarizing plate with an optical structure and a display device provided with the optical structure.

A liquid crystal display device, which is an example of a display device, is used in various fields. The liquid crystal panel of the liquid crystal display device is roughly classified into a TN (Twisted Nematic) method, a VA (Vertical Alignment) method, and an IPS (In-Plane Switching) method.

In a liquid crystal display device, a color is expressed by mixing a plurality of lights having different wavelengths, but the intensity of light having different wavelengths may differ greatly depending on the angle of light transmitted through the liquid crystal. Specifically, for example, the difference between the intensity of light of one wavelength and the intensity of light of the other wavelength among two different wavelengths of light may be significantly different between the front view and the high angle side. In a liquid crystal display device provided with a liquid crystal panel having such characteristics, the color tone when viewed from an angle can be significantly changed from the color tone when viewed from the front.

For example, in a VA liquid crystal panel, black is displayed when the voltage applied to the liquid crystal molecules is off, and very little light leaks in the front direction from the part displaying black, so that the contrast ratio in front view is very high. Can be as high as possible. On the other hand, when the display surface is viewed from an inclined direction with respect to the normal direction, a relatively large amount of light leaks diagonally from the black pixels in the front view, so that the front view The contrast ratio may be significantly reduced and the tint may change significantly as compared with the case, and as a result, the contrast ratio and the tint within the viewing angle may vary greatly.

Further, in the VA type liquid crystal panel, for example, when the intensity of red and green light among red, green and blue is weakened or blocked to display blue, the red and green light leaks diagonally. , It is easy for a situation in which the color tone changes significantly between when viewed from the front and when viewed from an angle.
In addition, since the emission spectrum shape change with respect to the viewing angle of blue display is strong (compared to red display and green display), specifically, "intensity of wavelength component corresponding to green" is changed to "wavelength component corresponding to blue". The display color when viewed from an angle tends to turn yellow with respect to the front view due to a change that increases with respect to "intensity".

In view of the above-mentioned problems of contrast ratio variation and color change, in the VA type liquid crystal panel, cells may be formed in a color filter with a plurality of types of patterns. In this method, for example, by making the light distribution characteristics of light transmitted through cells having different patterns different from each other, it is possible to suppress the difference between the color tone when viewed from an angle and the color tone when viewed from the front.

However, in recent years, the definition of liquid crystal display devices has been rapidly increasing, and it is very troublesome to process a plurality of types of cells as described above on a color filter corresponding to a desired high resolution. In some cases, processing may not be possible depending on the desired resolution. In particular, in the VA method, it is generally necessary to make the cell division finer than in other formats such as the IPS method, so it is necessary to obtain a cell structure that can effectively suppress color changes while achieving the desired high resolution. May be difficult. On the other hand, it has been conventionally proposed that the color change is not suppressed on the liquid crystal panel side but is performed by an optical sheet provided on the display surface of the liquid crystal panel. This type of optical sheet is disclosed in, for example, Patent Documents 1 to 6.

Japanese Unexamined Patent Publication No. 7-43704 Patent No. 3272833 Patent No. 3621959 Japanese Unexamined Patent Publication No. 2016-126350 Japanese Unexamined Patent Publication No. 2012-145944 Japanese Unexamined Patent Publication No. 2011-118393

In a display device, it is generally desired that the display quality in the front view is in the best condition and the display quality in the entire viewing angle is not significantly deteriorated with respect to the front view. On the other hand, there is also a demand that good display quality is required in the front view and a part of the angle range on the high angle side, and display quality in other angle ranges is not strongly required. However, an optical sheet capable of meeting such a demand has not been known so far.

The inventor of the present invention has conducted diligent research to realize a structure that can meet the above-mentioned demands. Then, they have found that it is effective to use total reflection when locally obtaining good display quality in a part of the angle range inclined to the high angle side with respect to the front view direction.

Further, the optical member as disclosed in Patent Documents 1 to 6 may be provided with a surface material that forms the outermost surface on the light emitting side outside the layer that exerts an optical action on the incident light. Although such a surface material can function as a protective layer, it may reduce the brightness of the light emitted from the outermost surface, and particularly significantly reduce the brightness on the high angle side. Therefore, such a surface material may undesirably inhibit the effect of improving the viewing angle by the layer exerting an optical action.

The present invention has been made in consideration of the above circumstances, and is locally applied to a part of the angle range on the high angle side within the viewing angle while maintaining good display quality in the front view of the display device. It is an object of the present invention to provide an optical structure capable of obtaining good display quality, a polarizing plate with an optical structure provided with the optical structure, and a display device.

The optical structure according to the present invention is an optical structure arranged on a display surface of a display device, which is laminated on a low refractive index layer and the low refractive index layer, and has a refractive index of the low refractive index layer. The low refractive index layer is provided with a higher refractive index layer, the interface between the low refractive index layer and the high refractive index layer has a concave-convex shape, and the concave portion and the convex portion forming the concave-convex shape have a sheet-like low refractive index. The layers and the high refractive index layer are alternately arranged in the first direction parallel to the main surface, extend linearly along the second direction parallel to the main surface and intersecting the first direction, and the concave portion and the convex portion. Each of the portions has a flat portion extending along the plane direction of the low refractive index layer and the high refractive index layer, and the concave portion is a portion recessed toward the low refractive index layer side, and the convex portion. Is a portion that is convex toward the high refractive index layer side, and a side surface having the concave-convex shape is formed between the flat portion of the concave portion and the flat portion of the convex portion, and is adjacent to each other with the flat portion of the concave portion interposed therebetween. The two side surfaces of the uneven shape form a tapered shape from the high refractive index layer side toward the low refractive index layer side, and the two side surfaces of the uneven shape adjacent to each other with the flat portion of the convex portion interposed therebetween , An optical structure in which a tapered shape is formed from the low refractive index layer side toward the high refractive index layer side, and the high refractive index layer is arranged so as to face the display surface side of the display device. ..

In the optical structure according to the present invention, the side surface of the concave-convex shape is at least one of a curved surface that is convex toward the high-refractive index layer side, a bent surface, or at least one curved surface that is convex toward the high-refractive index layer side. It may be a surface including one plane.

In the optical structure according to the present invention, the side surface of the concavo-convex shape defined by a straight line connecting both end points of the side surface of the concavo-convex shape and the normal direction of the low refractive index layer and the high refractive index layer. The average slope angle of the above may be 11 degrees or more and 17 degrees or less.

In the optical structure according to the present invention, the difference between the maximum angle and the minimum angle formed by the side surface of the uneven shape with the normal direction of the low refractive index layer and the high refractive index layer is 14 degrees or more and 18 degrees or less. It may be.

In the optical structure according to the present invention, the ratio of the total length of the flat portion to the length of one cycle of the concave portion and the convex portion may be 0.75 or more and 0.85 or less.

In the optical structure according to the present invention, the light projected from the display surface of the display device to the outside through the optical structure is parallel to the normal direction of the low refractive index layer and the high refractive index layer. The light projected in the front view direction when observed from the front view direction of the display device and the direction inclined with respect to the front view direction in the plane including the front view direction and the first direction. The color change Δu'v'of the light projected in the inclined direction with respect to the color gradually increases from the front view direction to the tendency change angle set between 40 degrees and 55 degrees or less with respect to the front view direction. However, after the tendency change angle, the tendency may change to a decreasing tendency.

The color change Δu'v'at the tendency change angle of the light projected from the display surface to the outside through the optical structure is the light projected from the display surface to the outside without passing through the optical structure. It may be smaller than the color change Δu'v'at the angle corresponding to the tendency change angle.

Each value of the color change Δu'v'of the light projected from the display surface to the outside through the optical structure in the range of 60 degrees or more and 70 degrees or less with respect to the front view direction is from the display surface. It may be less than half of the value of the color change Δu'v'at the position corresponding to each value of the light projected to the outside without passing through the optical structure.

The optical structure according to the present invention further includes a surface material arranged on the side of the low refractive index layer opposite to the high refractive index layer side, and the refractive index of the surface material may be 1.40 or less. ..

The surface material may form the outermost surface on the side opposite to the display surface side of the display device.

The polarizing plate with an optical structure according to the present invention is a polarizing plate with an optical structure including the polarizing plate and the optical structure on the surface of the polarizing plate.

The display device according to the present invention is a display device in which the optical structure is arranged on a display surface.

The display device may also have a liquid crystal panel having the display surface and a back surface arranged to face the display surface, and a surface light source device arranged to face the back surface of the liquid crystal panel. Good.

In the liquid crystal panel, when the voltage with respect to the liquid crystal molecules is off or the minimum value, the liquid crystal molecules are oriented along the normal direction of the display surface to block the light from the surface light source device, and the liquid crystal. A VA type liquid crystal configured to gradually increase the transmittance of light from the surface light source device by gradually increasing the voltage with respect to the molecules and gradually inclining the liquid crystal molecules toward the side along the display surface. It may be a panel.

Further, another display device according to the present invention includes an organic LED panel, an optical structure, and a circular polarizing plate, and the optical structure includes a low refractive index layer including a plurality of lens portions and the plurality of. The lens portion has a high refractive index layer which is provided so as to fill the space between the lens portions and has a refractive index higher than that of the low refractive index layer, and the lens portion is a column tapered toward the high refractive index layer side. The high refractive index layer has a shape and has a flat portion at the tip on the high refractive index layer side, and the optical structure is arranged between the organic LED panel and the circular polarizing plate. The low refractive index layer is an optical structure facing the organic LED panel side and facing the circular plate plate side.
In this case, the plurality of lens portions may be arranged two-dimensionally.

Further, the other polarizing plate with an optical structure according to the present invention is
A circular polarizing plate, a low refractive index layer containing a plurality of lens portions, and
It has a high refractive index layer that is provided so as to fill the space between the plurality of lens portions and has a higher refractive index than the low refractive index layer, and the lens portion is tapered toward the high refractive index layer side. An optical structure having a columnar shape and having a flat portion at the tip on the high refractive index layer side.
A polarizing plate with an optical structure in which the low refractive index layer and the circular polarizing plate are bonded together.

According to the present invention, it is possible to locally obtain good display quality in a part of the angle range on the high angle side within the viewing angle while maintaining good display quality in the front view of the display device.

It is a schematic sectional drawing of the display device provided with the optical structure which concerns on one Embodiment of this invention. It is the schematic sectional drawing of the display device for demonstrating the behavior of light in the display device shown in FIG. It is an enlarged sectional view of the optical structure shown in FIG. It is an enlarged view of the concavo-convex shape formed at the interface between the high refractive index layer and the low refractive index layer of the optical structure shown in FIG. The color change Δu'v'in the viewing angle of the display device provided with the optical structure shown in FIG. 1 and the color change Δu'v'in the viewing angle of the display device not attached with the optical structure are shown. It is a figure which shows the graph. It is sectional drawing of the optical structure which concerns on one modification. It is sectional drawing of the optical structure which concerns on one modification. It is sectional drawing of the optical structure which concerns on one modification. It is sectional drawing of the optical structure which concerns on one modification. It is sectional drawing of the optical structure which concerns on one modification. It is a figure which shows schematic structure of the display device which concerns on one modification. It is a partial perspective view of the optical structure provided in the display device shown in FIG. (A) is a diagram showing the arrangement of the lens portions of the low refractive index layer of the optical structure shown in FIG. 12, and (B) is a diagram showing a modified example of the arrangement of the lens portions. (A) and (B) are diagrams showing a modified example of the optical structure shown in FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In this specification, terms such as "sheet", "film", "board", and "layer" are not distinguished from each other based only on the difference in names. Thus, for example, "sheet" is a concept that includes members that can also be called films, plates, or layers. Further, in the present specification, the "sheet surface (plate surface, film surface)" refers to the plane direction (plane direction) of the target sheet-like member when the target sheet-like member is viewed as a whole and in a broad view. ) And the surface that matches. The "sheet surface (plate surface, film surface)" may be referred to as a main surface. Further, in the present specification, the normal direction of the sheet-shaped member refers to the normal direction of the target sheet-shaped member to the seat surface.

First, the basic configuration of the display device 10 including the optical structure 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a schematic cross-sectional view of a display device 10 including an optical structure 100, and FIG. 2 is a schematic cross-sectional view of the display device 10 for explaining the behavior of light in the display device 10. FIG. 3 is an enlarged cross-sectional view of the optical structure 100, and FIG. 4 is an enlarged view of an uneven shape formed at the interface between the high refractive index layer and the low refractive index layer of the optical structure 100. In each of the above sectional views and the other sectional views used in the following description, hatching may be omitted for convenience of explanation. Further, FIGS. 1-4, the display device and the first direction d ₁ parallel to each sheet surface of the optical structure 100 of the liquid crystal panel 15 and sheet at 10, the optical liquid crystal panel 15 and the sheet in the display device 10 The normal direction of the structure 100 and the cross-sectional view of the plane including the structure 100 are shown. In the present embodiment, the first direction d ₁ is in a direction parallel to the direction in which the light source 24 of the surface light source device 20 which is an edge light type in the display device 10 emits light to the light guide plate 30 as described later. There is also a direction in which the concave portions 121 and the convex portions 122 of the concave-convex shape 120, which will be described later, are alternately arranged in the optical structure 100.

(Display device)
First, the overall configuration of the display device 10 will be described. As shown in FIG. 1, the display device 10 according to the present embodiment is arranged so as to face the liquid crystal panel 15 and the back surface 15B of the liquid crystal panel 15 and illuminates the liquid crystal panel 15 in a planar manner from the back surface 15B side. It includes a device 20 and a sheet-shaped optical structure 100 arranged on the display surface 15A of the liquid crystal panel 15. The liquid crystal panel 15 has a display surface 15A for displaying an image which is a still image or a moving image, and a back surface 15B arranged so as to face 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 region (subpixel) forming a pixel, and the display surface 15A is driven by the drive of the liquid crystal panel 15. The image is displayed.

The illustrated liquid crystal panel 15 is a liquid crystal arranged between the upper polarizing plate 13 arranged on the light emitting side, the lower polarizing plate 14 arranged on the light entering side, and the upper polarizing plate 13 and the lower polarizing plate 14. It has a layer 12. The polarizing plates 14 and 13 decompose the incident light into two orthogonal polarization components (for example, P wave and S wave) and vibrate in one direction (direction parallel to the transmission axis) (for example, P). It has a function of transmitting a wave) and absorbing a linearly polarized light component (for example, an S wave) that vibrates in the other direction (direction parallel to the absorption axis) orthogonal to the one direction.

In the liquid crystal layer 12, a voltage can be applied to each region forming one pixel, and the orientation direction of the liquid crystal molecules in the liquid crystal layer 12 changes depending on the presence or absence of the voltage application. As an example, the polarization component in a specific direction transmitted through the lower polarizing plate 14 arranged on the light entry side rotates its polarization direction by 90 ° when passing through the liquid crystal layer 12 to which no voltage is applied, while rotating the polarization direction by 90 °. , The polarization direction is maintained as it passes through the liquid crystal layer 12 to which the voltage is applied. In this case, depending on whether a voltage is applied to the liquid crystal layer 12, whether the polarizing component that vibrates in a specific direction transmitted through the lower polarizing plate 14 further transmits through the upper polarizing plate 13 arranged on the light emitting side of the lower polarizing plate 14. Alternatively, it can be controlled whether it is absorbed by the upper polarizing plate 13 and blocked. In this way, the liquid crystal panel 15 can control the transmission or blocking of light from the surface light source device 20 for each region forming the pixel.

In the present embodiment, the liquid crystal panel 15 is a VA (Vertical Alignment) type liquid crystal panel as an example. Therefore, in the liquid crystal panel 15, when the voltage for the liquid crystal molecules in the liquid crystal layer 12 is off or the minimum value, the liquid crystal molecules are oriented along the normal direction of the display surface 15A to block the light from the surface light source device 20. By gradually increasing the voltage with respect to the liquid crystal molecules and gradually inclining the liquid crystal molecules toward the side along the display surface 15A, the transmittance of light from the surface light source device 20 is gradually increased. Have. The liquid crystal panel 15 is not limited to the VA type, and may be a TN (Twisted Nematic) type liquid crystal panel or an IPS (In-Plane Switching) type liquid crystal panel. The details of the liquid crystal panel 15 are described in various publicly known documents (for example, "Flat Panel Display Dictionary (supervised by Tatsuo Uchida and Hiraki Uchiike)" published by Kogyo Chosakai in 2001), and further details are described here. Explanation is omitted.

Next, the surface light source device 20 will be described. The surface light source device 20 has a light emitting surface 21 that emits light in a planar shape, and in the present embodiment, it is used as a device that illuminates the liquid crystal panel 15 from the back surface 15B side. As shown in FIG. 1, the surface light source device 20 is configured as an edge light type surface light source device as an example, and is lateral to the light guide plate 30 and one side (left side in FIG. 1) of the light guide plate 30. It has a light source 24 arranged in the light source 24, and an optical sheet (prism sheet) 60 and a reflection sheet 28 arranged so as to face each other of the light guide plate 30. In the illustrated example, the optical sheet 60 is arranged facing the liquid crystal panel 15. The light emitting surface 21 of the surface light source device 20 is defined by the light emitting surface 61 of the optical sheet 60.

In the illustrated example, the light emitting surface 31 of the light guide plate 30 has a quadrangular shape (a shape viewed from above) in a plan view similar to the display surface 15A of the liquid crystal panel 15 and the light emitting surface 21 of the surface light source device 20. It is formed. As a result, the light guide plate 30 is configured as a rectangular parallelepiped member having a pair of main surfaces (emission surface 31 and back surface 32) and whose sides in the thickness direction are smaller than the other sides. The sides defined between the pair of main faces include four faces. Similarly, the optical sheet 60 and the reflective sheet 28 are generally configured as rectangular parallelepiped members whose sides in the thickness direction are relatively smaller than the other sides.

As shown in FIGS. 1 and 2, the light guide plate 30 has a back surface 32 composed of the above-mentioned light emitting surface 31 formed by one main surface on the liquid crystal panel 15 side and the other main surface facing the light emitting surface 31. And a side surface extending between the light emitting surface 31 and the back surface 32, and _one side surface of the two surfaces facing the first direction d1 of the side surfaces forms the light entering surface 33. .. Then, as shown in FIGS. 1 and 2, a light source 24 is provided facing the light entering surface 33. The light incident on the light guide plate 30 from the light incident surface 33, as shown in FIG. 2, toward the opposite surface 34 facing the first direction (light guide direction) d light incident surface 33 along _one generally the first direction (light guide direction) light guide plate 30 along the d ₁ comes to be guided. Here, the display device 10 according to this embodiment, which first direction d ₁ is assumed to be arranged along the horizontal direction, that is the horizontal direction, in this case, the light from the light source 24 is It will be guided in the left-right direction. However, such an arrangement is not particularly limited, and the display device may be arranged in another manner. Further, in the present embodiment, the surface light source device 20 is an edge light type, but the surface light source device 20 may be another type such as a direct type or a backside illumination type.

More specifically about the light guide plate 30, in the present embodiment, the back surface 32 of the light guide plate 30 is formed as an uneven surface. As a specific configuration, as shown in FIG. 2, the back surface 32 includes an inclined surface 37, a stepped surface 38 extending in the normal direction of the light guide plate 30, and a connecting surface 39 extending in the plate surface direction of the light guide plate 30. have. The light guiding in the light guide plate 30 is performed by the total reflection action on the pair of main surfaces 31 and 32 of the light guide plate 30. On the other hand, the inclined surface 37 is inclined with respect to the plate surface of the light guide plate 30 so as to approach the light emitting surface 31 from the light entering surface 33 side toward the opposite surface 34 side. Therefore, for the light reflected by the inclined surface 37, the incident angle when it is incident on the pair of main surfaces 31 and 32 becomes small. Then, when the angle of incidence on the pair of main surfaces 31 and 32 becomes less than the total reflection critical angle due to reflection on the inclined surface 37, the light is emitted from the light guide plate 30 as shown in L1 of FIG. Become. That is, the inclined surface 37 functions as an element for extracting light from the light guide plate 30. The light guide plate 30 is not limited to the embodiment of the present embodiment, and may be another embodiment such as a dot pattern method.

Further, the light source 24 may be configured in various forms such as a fluorescent lamp such as a linear cold cathode tube, a point LED (light emitting diode), and an incandescent lamp. The light source 24 in the present embodiment is composed of a large number of point-shaped light emitters 25 arranged side by side along the longitudinal direction of the light entry surface 33, specifically, a large number of light emitting diodes (LEDs).

Further, the reflective sheet 28 is a member arranged so as to face the back surface 32 of the light guide plate 30, and reflects the light leaked from the back surface 32 of the light guide plate 30 and causes the light to enter the light guide plate 30 again. It is a member for. The reflective sheet 28 includes a white diffuse reflective sheet, a sheet made of a material having a high reflectance such as metal, and a thin film made of a material having a high reflectance (for example, a metal thin film or a dielectric multilayer film) as a surface layer. And so on. The reflection on the reflection sheet 28 may be regular reflection (specular reflection) or diffuse reflection. When the reflection on the reflection sheet 28 is diffuse reflection, the diffuse reflection may be isotropic diffuse reflection or anisotropic diffuse reflection.

Further, the optical sheet 60 is a member having a function of changing the traveling direction of transmitted light. As shown in FIG. 2, the optical sheet 60 according to this example has a main body portion 65 formed in a plate shape and a plurality of unit prisms (unit shape elements, units) formed on the light receiving side surface 67 of the main body portion 65. It has an optical element (unit lens) 70 and. The main body 65 is configured as a flat plate-like member having a pair of parallel main surfaces. In the illustrated example, the unit prisms 70 are arranged side by side on the light entering side surface 67 of the main body 65, and each unit prism 70 is formed in a columnar shape and extends in a direction intersecting the arrangement direction thereof. In the present embodiment, one optical sheet 60 is provided on the light guide plate 30, but a plurality of optical sheets may be provided on the light guide plate 30. In this case, the directions of the grooves of the prisms of each optical sheet may be different from each other.

The surface light source device 20 as described above is provided with the optical sheet 60, so that the light from the light guide plate 30 is converted into a desired traveling direction and incident on the liquid crystal panel 15. Then, as described above, the light incident on the liquid crystal panel 15 is controlled to transmit or block in the liquid crystal layer 12 for each pixel formation region in response to the voltage application, whereby an image is displayed on the display surface 15A of the liquid crystal panel 15. It will be displayed.

(Optical structure)
Next, the optical structure 100 will be described in detail with reference to FIGS. 2 to 4. As shown in FIGS. 2 and 3, the optical structure 100 according to the present embodiment is a sheet-like or film-like base material 101 having a light emitting surface 101A and a back surface 101B arranged to face the light emitting surface 101A. A low refractive index layer 102 provided on the back surface 101B of the base material 101 and formed in the form of a sheet or a film extending along the base material 101 and having a pair of main surfaces facing each other in the thickness direction, and low refractive index. It is provided on the surface of the rate layer 102 opposite to the base material 101 side, is formed in the form of a sheet or a film extending along the base material 101, has a pair of main surfaces facing each other in the thickness direction, and has. The high refractive index layer 103 having a higher refractive index than the low refractive index layer 102 is arranged on the side opposite to the high refractive index layer 103 side of the low refractive index layer 102, and in this example, it is on the light emitting surface 101A of the base material 101. The sheet-like or film-like antireflection layer 104 provided in the above is provided. The antireflection layer 104 in the present embodiment is a member corresponding to a so-called surface material forming the outermost surface on the light emitting side.

The base material 101 is a transparent base material having light transmittance made of resin, glass, or the like, and examples of the material thereof include polyethylene terephthalate, polyoliphin, polycarbonate, polyacrylate, polyamide, glass, and triacetyl cellulose. .. That is, the base material 101 is composed of, for example, polyethylene terephthalate, polyoliffin, polycarbonate, polyacrylate, polyamide, a film containing triacetyl cellulose as a main component, glass, and the like. 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. In addition, the principal component means a component contained in a ratio of 50% or more with respect to the whole substance among a plurality of components constituting a certain substance, or a component contained most.

As shown in FIG. 2, the optical structure 100 is arranged so that the high refractive index layer 103 faces the display surface 15A side of the display device 10 (liquid crystal panel 15), and in the illustrated example, the high refractive index layer 103 is arranged. Is in direct contact with the display surface 15A of the liquid crystal panel 15. Further, the antireflection layer 104 forms the outermost surface of the optical structure 100 on the side opposite to the display surface 15A side of the liquid crystal panel 15, and reflects the surface of external light incident on the optical structure 100. It is provided to suppress it. This makes it possible to prevent the visibility of the image displayed on the display device 10 from being impaired by the surface reflection of external light.

The refractive index of the antireflection layer 104 is 1.40 or less, and more specifically, it is 1.35 as an example in the present embodiment. The general refractive index of a surface material such as an antireflection layer is about 1.45, and a member having such a refractive index can be obtained at a relatively low cost, so that the cost can be suppressed. However, when a surface material having a refractive index of about 1.45 is used, the total reflection critical angle at which the light emitted from the display device side starts to be totally reflected at the interface with air becomes relatively small, so that the light The amount taken out is reduced. As a result, when observing the image on the display device, the brightness of the image may be lowered, and in particular, the brightness on the high angle side may be significantly lowered. On the other hand, in the present embodiment, by setting the refractive index of the antireflection layer 104 to 1.40 or less, the total reflection critical angle at which light starts to be totally reflected at the interface between the antireflection layer 104 and air is increased. , Increases the amount of light extracted as compared with the case of general surface materials. As a result, it is possible to prevent the brightness within the viewing angle from being undesirably reduced.

The inventor of the present invention has conducted diligent research, and in order to achieve both prevention of surface reflection of external light and sufficient extraction of light from the display device, the refractive index of the antireflection layer 104 as a surface material is 1.28 or more. It was found from experiments and simulations that it is preferably 1.40 or less, and particularly preferably 1.30 or more and 1.36 or less. In the present embodiment, the antireflection layer 104 as the surface material has a function of suppressing the surface reflection of external light, but the surface material may not have such a function. Further, in the optical structure 100, the effect of suppressing the color change in the viewing angle can be obtained by the optical action exerted on the light by the low refractive index layer 102 and the high refractive index layer 103 described below. Can be obtained even if the antireflection layer 104 is not provided.

The antireflection layer 104 is transparent, and the thickness of the antireflection layer 104 is, for example, 0.05 μm or more. It is μm or less. The antireflection layer 104 may contain, for example, hollow silica fine particles and a base resin that holds the hollow silica fine particles, but is not particularly limited as long as a desired refractive index can be obtained.

When the antireflection layer 104 contains hollow silica fine particles and a base resin that holds hollow silica fine particles, more specifically, for example, (meth) acrylic resin, hollow silica fine particles, and reactive silica fine particles. And two kinds of antifouling agents may be contained.

The (meth) acrylic resin corresponds to the base resin, and is a component that functions as a binder component of hollow silica fine particles and reactive silica fine particles in the antireflection layer 104. In addition, in this specification, "(meth) acrylic" means acrylic or methacrylic. Examples of the (meth) acrylic resin include polymers or copolymers of the (meth) acrylic monomer, and the (meth) acrylic monomer is not particularly limited, but for example, pentaerythritol tri (meth) acrylate and dipenta. Elythritol hexa (meth) acrylate, pentaerythritol (meth) tetraacrylate, dipentaerythritol penta (meth) acrylate, trimethylolpropanthry (meth) acrylate, dipentaerythritol tetra (meth) acrylate, isocyanuric acid EO-modified tri (meth) Acrylate and the like are preferably mentioned. Further, these (meth) acrylate monomers may be those in which a part of the molecular skeleton is modified, and are modified with ethylene oxide, propylene oxide, caprolactone, isocyanuric acid, alkyl, cyclic alkyl, aromatic, bisphenol and the like. Things can also be used. These (meth) acrylic monomers may be used alone or in combination of two or more. These (meth) acrylic monomers are excellent in curing reactivity and can improve the hardness of the obtained antireflection layer 104.

The polymer or copolymer obtained by curing the (meth) acrylic monomer preferably has a refractive index of 1.47 or more and 1.53 or less. It is virtually impossible to have a refractive index of less than 1.47, and if it exceeds 1.53, it may not be possible to obtain an antireflection layer having a sufficiently low refractive index.

The weight average molecular weight of the (meth) acrylic monomer is preferably 250 or more and 1000 or less. If it is less than 250, the number of functional groups is reduced, so that the hardness of the obtained antireflection layer 104 may be lowered. If it exceeds 1000, the functional group equivalent (number of functional groups / molecular weight) is generally small, so that the crosslink density is low and the antireflection layer 104 having sufficient hardness may not be obtained. The weight average molecular weight of the (meth) acrylic monomer can be determined by gel permeation chromatography (GPC) in terms of polystyrene. Tetrahydrofuran or chloroform can be used as the solvent for the GPC mobile phase. The measurement column may be used in combination with a commercially available column for tetrahydrofuran or chloroform. Examples of the commercially available column include Shodex GPC KF-801 and GPC-KF800D (both trade names, manufactured by Showa Denko KK) and the like. RI (differential refractometer) detector and UV detector may be used as the detector. Using such a solvent, a column, and a detector, the weight average molecular weight can be appropriately measured by, for example, a GPC system such as Shodex GPC-101 (manufactured by Showa Denko KK).

The hollow silica fine particles are components that play a role in lowering the refractive index of the antireflection layer 104 while maintaining the layer strength. In the present specification, the "hollow silica fine particles" are structures in which gas is filled and / or porous structures containing gas, and the occupancy rate of gas is higher than the original refractive index of silica fine particles. It means silica fine particles whose refractive index decreases in inverse proportion to. The antireflection layer 104 can achieve a desired reflectance by containing hollow silica fine particles. Also, the antireflection layer 104 can be stiff and have a lower refractive index.

The hollow silica fine particles preferably have an average particle diameter of 5 nm or more and 300 nm or less, more preferably 8 nm or more and 100 nm or less, and further preferably 10 nm or more and 80 nm or less. If it is less than 5 nm, the porosity of the antireflection layer 104 is insufficient, and the refractive index cannot be sufficiently lowered. On the other hand, if it exceeds 300 nm, unevenness is formed on the surface of the antireflection layer 104, the scratch resistance of the optical structure 100 deteriorates, and the strength of the hollow silica fine particles themselves becomes weak, so that the antireflection layer 104 This leads to a decrease in film strength. The preferable lower limit of the average particle size of the hollow silica fine particles is 10 nm, and the preferable upper limit is 80 nm. Within this range, the desired reflectance can be achieved while maintaining the strength of the antireflection layer 104. The average particle size of the hollow silica fine particles means, for example, a value measured by observation by a dynamic light scattering method or a cross-sectional TEM method.

Specific examples of the hollow silica fine particles are not particularly limited, and for example, hollow silica fine particles prepared by using the technique disclosed in Japanese Patent Application Laid-Open No. 2001-233611 are preferable. Since the hollow silica fine particles are easy to manufacture and have high hardness of themselves, when the antireflection layer 104 is formed by mixing with an organic binder component, the layer strength is improved and the refractive index is lowered. It becomes possible to adjust.

The porosity of the hollow silica fine particles is preferably 6.4% or more and 80.0% or less. If the porosity is less than 6.4%, the refractive index of the antireflection layer 104 cannot be sufficiently lowered. On the other hand, if the porosity exceeds 80.0%, the strength of the hollow silica fine particles may decrease and the strength of the entire antireflection layer 104 may become insufficient. The porosity of the hollow silica fine particles has a more preferable lower limit of 8.5% and a more preferable upper limit of 76.4%. By having a porosity in this range, the antireflection layer 104 can be made to have a sufficiently low refractive index and has excellent strength.

The hollow silica fine particles may be contained in an amount of 80 parts by mass or more and 200 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic resin. The hollow silica fine particles are preferably contained in an amount of 100 parts by mass or more and 180 parts by mass or less with respect to 100 parts by mass of the acrylic resin. If the amount of the hollow silica fine particles is less than 80 parts by mass with respect to 100 parts by mass of the (meth) acrylic resin, the refractive index of the antireflection layer 104 cannot be sufficiently lowered. If the amount of the hollow silica fine particles exceeds 200 parts by mass with respect to 100 parts by mass of the (meth) acrylic resin, the scratch resistance is lowered. When the hollow silica fine particles are contained in an amount of 100 parts by mass or more and 180 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic resin, the desired reflectance is obtained while maintaining the strength of the antireflection layer 104. Can be achieved.

The reactive silica fine particles are silica fine particles having a reactive functional group on the surface. The reactive silica fine particles are components that play a role in increasing the surface hardness of the antireflection layer 104. The reactive functional group is not particularly limited, and is appropriately selected so as to be capable of cross-linking with the (meth) acrylic resin, and an ultraviolet curable functional group is preferably used. Specific examples of the reactive functional group include an ethylenically unsaturated bond such as a (meth) acryloyl group, a vinyl group and an allyl group, and an epoxy group. Of these, an ethylenically unsaturated bond is preferable.

As such reactive silica fine particles, it is preferable that at least a part of the surface of the silica fine particles is coated with an organic component and the surface has a reactive functional group introduced by the organic component. Here, the organic component is a component containing carbon. Further, in an embodiment in which at least a part of the surface of the silica fine particles is coated with an organic component, for example, a compound containing an organic component such as a silane coupling agent reacts with a hydroxyl group existing on the surface of the silica fine particles to react with the surface. In addition to the embodiment in which the organic component is bonded to a part of the surface, or the compound containing the organic component having an isocyanate group on the hydroxyl group existing on the surface of the silica fine particles reacts and the organic component is bonded to a part of the surface. For example, an embodiment in which an organic component is attached to a hydroxyl group existing on the surface of the silica fine particles by an interaction such as a hydrogen bond is included.

The method for preparing reactive silica fine particles having an organic component coated on at least a part of the surface of the silica fine particles and having a reactive functional group introduced by the organic component on the surface is not particularly limited, and a conventionally known method is used. Can be used.

The reactive silica fine particles preferably have an average particle diameter of 1 nm or more and 25 nm or less. If it is less than 1 nm, it may not be possible to contribute to the improvement of the hardness of the antireflection layer 104, and if it exceeds 25 nm, the transparency of the antireflection layer 104 may be lowered, which may lead to deterioration of transmittance and increase of haze. In addition, it may cause defects in the antireflection layer 104. The more preferable lower limit of the average particle size of the reactive silica fine particles is 5 nm, and the more preferable upper limit is 20 nm. In the present specification, the average particle size of the reactive silica fine particles is 50% particle size when the reactive silica fine particles in the solution are measured by a dynamic light scattering method and the particle size distribution is expressed as a cumulative distribution. It means (d50 median diameter). The average particle size can be measured using a Microtrac particle size analyzer manufactured by Nikkiso Co., Ltd. It can also be confirmed by observing the cross section by the TEM method.

The reactive silica fine particles are preferably dispersed as single particles. For example, 3 to 20, preferably 3 to 10 reactive silica fine particles are bonded by an inorganic chemical bond. (Chain particles) may be included. By containing such chain particles, the scratch resistance of the antireflection layer 104 can be improved. The chain particles are preferably contained in a proportion of 0 to 80% by mass in 100% by mass of all the reactive silica fine particles (single particles + chain particles). If it exceeds 80% by mass, it may cause defects in the antireflection layer 104. The more preferable lower limit of the content ratio of the chain particles is 10% by mass, and the more preferable upper limit is 70% by mass.

Examples of the inorganic chemical bond include an ionic bond, a metal bond, a coordination bond and a covalent bond. Among them, bonds in which the bound spherical silica fine particles are not dispersed even when the above reactive silica fine particles are added to a polar solvent, specifically, metal bonds, coordination bonds, and covalent bonds are preferable, and further, covalent bonds are preferable. Bonding is preferred. Examples of the polar solvent include water and lower alcohols such as methanol, ethanol and isopropyl alcohol.

For the average number of bonds of the reactive silica fine particles, the cross section of the antireflection layer 104 was observed using an SEM image or a TEM image, 100 observed aggregated particles were selected, and the reactive silica contained in each chain particle was selected. The fine particles can be counted and calculated as the average value. The average particle size of the chain particles is the average of the major axis and the minor axis.

Chain-like particles to which such reactive silica fine particles are bonded can be obtained by a conventionally known method. For example, it can be obtained by adjusting the concentration or pH of the dispersion liquid of the reactive silica fine particles in the monodispersed state and performing hydrothermal treatment at a high temperature of 100 ° C. or higher. At this time, if necessary, a binder component can be added to promote the binding of the reactive silica fine particles. Further, the ions may be removed by passing the dispersion liquid of the reactive silica fine particles used through the ion exchange resin. By such an ion exchange treatment, the binding of the reactive silica fine particles can be promoted. After the hydrothermal treatment, the ion exchange treatment may be performed again.

The above-mentioned reactive silica fine particles are preferably contained in an amount of 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic resin. If it is less than 5 parts by mass, the hardness of the antireflection layer 104 cannot be sufficiently increased, and if it exceeds 60 parts by mass, the adhesion to other layers may be insufficient. In addition, the effect of adding the reactive silica fine particles is not seen, which leads to an increase in manufacturing cost and an increase in reflectance. The preferable lower limit of the content of the reactive silica fine particles is 10 parts by mass, and the preferable upper limit is 50 parts by mass. Within this range, the film strength of the antireflection layer 104 can be improved without impairing the reflectance and the like.

Further, since the scratch resistance of the antireflection layer 104 can be further improved, the content of the reactive silica fine particles in the antireflection layer 104 is appropriately adjusted in relation to the content of the hollow silica fine particles described above. Is preferable. Specifically, the blending ratio of the hollow silica fine particles to the (meth) acrylic resin (content of the hollow silica fine particles / content of the (meth) acrylic resin) is 0.9 to 1.1 ((meth)). When the hollow silica fine particles are 90 parts by mass or more and 110 parts by mass or less with respect to 100 parts by mass of the acrylic resin, the content of the reactive silica fine particles is 5 parts by mass with respect to 100 parts by mass of the (meth) acrylic resin. It is preferably 10 parts or more and 40 parts by mass or less. Further, the compounding ratio of the hollow silica fine particles to the (meth) acrylic resin is 1.1 to 1.4 (100 parts by mass) of the (meth) acrylic resin, and 110 parts by mass or more and 140 parts by mass of the hollow silica fine particles. In the case of (below), the content of the reactive silica fine particles is preferably 40 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the (meth) acrylic resin.

In addition, the antireflection layer 104 contains an antifouling agent made of a fluorine-based compound and an antifouling agent made of a fluorine-silicone compound as the antifouling agent. By using the two types of antifouling agents in this way, for example, by containing the antifouling agent composed of the above-mentioned fluorine-based compound, the fingerprint adhesion prevention performance and the fingerprint wiping performance are excellent. Further, by containing the antifouling agent composed of the above-mentioned fluorine-silicone compound, the magic repelling performance, the magic wiping performance, the slipperiness and the scratch resistance are excellent, and the antireflection layer 104 has a defect. Can be suppressed.

The content of the fluorine-based compound is not particularly limited, but is 1.0 part by mass or more and 10.0 part by mass or less with respect to 100 parts by mass in total of the hollow silica fine particles and the (meth) acrylic resin. preferable.

When the antireflection layer 104 is configured as described above, each mass part of the hollow silica fine particles, the (meth) acrylic resin as the base resin, the reactive silica fine particles, etc. in the antireflection layer 104 is, for example, the antireflection layer 104. It can be estimated by specifying the area ratio of each component using the SEM image of the cross section of the above and considering the specific gravity of each component. It can also be specified by specifying the manufacturing process of the antireflection layer 104.

Subsequently, the low refractive index layer 102 and the high refractive index layer 103 will be described. As shown in FIG. 3, in the present embodiment, the low refractive index layer 102 has a plurality of lens portions 110 on the surface opposite to the base material 101 side, and the lens portion 110 has the low refractive index layer 102. and it is formed so as to project the high refractive index layer 103 side along the common normal direction d ₃ of the high refractive index layer 103. That is, the low refractive index layer 102 has a film-like layer body 102A having a front surface facing the base material 101 side and a back surface facing the surface and facing the high refractive index layer 103 side, and on the back surface of the layer body 102A. It integrally has a plurality of lens units 110 arranged side by side. On the other hand, the high refractive index layer 103 is laminated on the low refractive index layer 102 so as to cover the lens portion 110 and fill the space between the plurality of lens portions 110. As a result, in the present embodiment, the interface between the low refractive index layer 102 and the high refractive index layer 103 forms an uneven shape 120.

The concave-convex shape 120 is formed by forming a shape of one cycle with one concave portion 121 and a convex portion 122, and repeatedly forming the shape of this one cycle. The low refractive index layer 102 is recessed toward the low refractive index layer 102 with respect to the reference line SL extending parallel to the main surfaces of the low refractive index layer 102 and the high refractive index layer 103 through the midpoint between the bottom of the concave portion 121 and the top of the convex portion 122. The portion corresponds to the concave portion 121, and the portion that is convex toward the high refractive index layer 103 with respect to the reference line SL corresponds to the convex portion 122. Each recess 121 and projection 122 are disposed in a first direction d ₁ parallel to the main surface of the low refractive index layer 102 and the high-refractive index layer 103, the first direction d ₁ and the non-parallel, in particular the first crossing the direction d _1, and extends linearly along the second direction d ₂ perpendicular in this example. As shown in FIG. 3, the normal direction d ₃ of the low refractive index layer 102 and the high refractive index layer 103 has a relationship orthogonal to both the first direction d ₁ and the second direction d ₂ . Further, the above-mentioned state of "extending parallel to the main surfaces of the low refractive index layer 102 and the high refractive index layer 103" is one of the flat sides of the low refractive index layer 102 and the high refractive index layer 103 in the present embodiment. The low refractive index layer 102 and the plane extending parallel to the main surface of the above and including the direction in which the concave portions 121 and the convex portions 122 at the interface between the low refractive index layer 102 and the high refractive index layer 103 are arranged and linearly extended. It means a state extending parallel to the other main surface of the high refractive index layer 103.

Here, each of the concave portion 121 and the convex portion 122 of the present embodiment has flat portions 121A and 122A extending along the plane direction of the low refractive index layer 102 and the high refractive index layer 103, respectively, as shown in FIG. More specifically, the bottom portion of the concave portion 121 is a flat portion 121A, and the top portion of the convex portion 122 is a flat portion 122A. Further, the side surface 120S of the uneven shape 120 extending between the flat portion 121A of the concave portion 121 and the flat portion 122A of the convex portion 122 has a curved surface that is convex toward the high refractive index layer 103 side. Side 120S, this is formed a straight line extending along a direction normal to d ₃ from the end point of the flat portion 121A so as not to exceed in the surface direction of connecting. As a result, the low refractive index layer 102 having the lens portion 110 forming the side surface 120S can be die-cut. In the present embodiment, the side surface 120S is a curved surface, but the side surface 120S may be a bent surface (polygonal shape) that is convex toward the high refractive index layer 103 side. Further, the side surface 120S formed as a curved surface may be formed along a circular arc or may be formed along an elliptical arc.

The uneven shape 120 as described above is displayed on the display surface 15A by exerting optical actions such as reflection, refraction, and transmission on the light for displaying the image emitted from the display surface 15A. It is provided to improve the display quality of the image. More specifically, in the optical structure 100 according to the present embodiment, as described above, the high refractive index layer 103 of the low refractive index layer 102 and the high refractive index layer 103 is the display surface 15A of the display device 10. Flat portions 121A and 122A are formed on the concave-convex shape 120 so as to be directed to the side, and two side surfaces 120S adjacent to each other across the flat portion 121A of the concave portion 121 are low-refractive index from the high refractive index layer 103 side. The two side surfaces 120S, which form a tapered shape toward the rate layer 102 side and are adjacent to each other across the flat portion 122A of the convex portion 122, have a tapered shape from the low refractive index layer 102 side toward the high refractive index layer 103 side. Form. As a result, good display quality can be locally obtained in a part of the angle range on the high angle side within the viewing angle while maintaining good display quality in the front view of the display device 10.

More specifically, when the above various shapes are adopted, the light entering the low refractive index layer 102 from the flat portion 122A of the convex portion 122 and heading from the low refractive index layer 102 to the side surface 120S is totally reflected by the side surface 120S. Instead, a part is reflected on the side surface 120S, and a part is refracted and transmitted. At this time, the reflected light gathers in the front view direction and an angle range close to this. Further, the light that does not enter the low refractive index layer 102 from the flat portion 122A of the convex portion 122 and is directed from the side surface 120S to the low refractive index layer 102 side is totally reflected by the side surface 120S and has an angle range on the high angle side. Gather at. Here, the variation in color change within the viewing angle that occurs in the liquid crystal display device can be caused by, for example, the ratio of the intensity of red, blue, and green light projected when displaying a color image changes depending on the angle. However, when the above shape is adopted, such red, blue, and green lights can be collected in the front view direction and an angle range close to this, and an angle range on the high angle side. Due to the concentration of light in these two regions, the present inventor presents the intensity of red, blue, and green light at a high angle to the ratio of the intensity of, for example, red, blue, and green light in the front view direction. It was found that the change in the ratio of the light can be suppressed, and the color change of the light in the angle range on the high angle side with respect to the color of the light projected in the front view direction can be effectively suppressed locally. In the present invention, various shapes as described above are adopted based on the knowledge as described above.

Further, the inventor of the present invention considers that the side surface 120S is a curved surface that is convex toward the high refractive index layer 103 side or a bent surface (polygonal shape) as in the present embodiment, the high angle side within the viewing angle. By making it possible to disperse the light in a part of the angle range of the above, it is possible to particularly effectively suppress the color change in the part of the angle range on the high angle side with respect to the color of the light projected in the front view direction. Also found, in this embodiment, a configuration in which the side surface 120S is a curved surface is adopted.

Further, in the present embodiment, the low refractive index layer 102 is 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 0.25 or less. And the high index of refraction layer 103 is selected. Further, the low refractive index layer 102 is arranged so as to be directed to the front side of the display device 10, that is, the direction in which light is projected, and the high refractive index layer 103 is directed to the display surface 15A side of the liquid crystal panel 15. Have been placed. In the illustrated example, the high refractive index layer 103 is an adhesive layer, and as shown in FIG. 2, the optical structure 100 is joined to the display surface 15A of the liquid crystal panel 15 by the high refractive index layer 103. .. The low refractive index layer 102 and the high refractive index layer 103 are also members having light transmittance, and the materials thereof are not particularly limited. The high refractive index layer 103 may be joined to the display surface 15A of the liquid crystal panel 15 via another layer, and may not be an adhesive layer.

The low refractive index layer 102 may be formed by, for example, 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 the ultraviolet curable resin, the ultraviolet curable resin may contain an acrylic resin or an epoxy resin.

Similarly, the high refractive index layer 103 may be formed by curing, for example, an ultraviolet curable resin, an electron beam curable resin, or a thermosetting resin. When the high refractive index layer 103 is formed by curing the ultraviolet curable resin, the ultraviolet curable resin may contain an acrylic resin or an epoxy resin. When the high refractive index layer 103 is formed as an adhesive layer, the high refractive index layer 103 may be formed from an acrylic resin pressure-sensitive adhesive.

Explaining the behavior of light in the display device 10 of the present embodiment as described above with reference to FIG. 2 and the like, when displaying an image on the display device 10 of the present embodiment, light is first emitted from the light source 24. Be irradiated. Thus the light incident from the light incident surface 33 into the light guide plate 30 is, as shown in FIG. 2, toward the opposite surface 34 facing the first direction d incidence surface 33 along _a generally first direction The inside of the light guide plate 30 is guided along d ₁ . The guided light repeats total reflection between the main surfaces 31 and 32 of the light guide plate 30, and when the angle of incidence on the main surface 31 becomes less than the total reflection critical angle, it is guided as shown in L1 of FIG. Light is emitted from the light plate 30. The light emitted from the light guide plate 30 is converted into a desired traveling direction by the unit prism 70 when passing through the optical sheet 60 and is incident on the liquid crystal panel 15. Next, the light incident on the liquid crystal panel 15 is controlled to be transmitted or blocked in the liquid crystal layer 12 for each pixel formation region according to the voltage application, whereby an image is displayed on the display surface 15A of the liquid crystal panel 15. ..

Then, in the present embodiment, the light emitted from the display surface 15A of the liquid crystal panel 15 is incident on the optical structure 100. At this time, the light incident on the optical structure 100 from the liquid crystal panel 15 side is imparted with an optical action by reflection and transmission (refraction) due to the uneven shape 120. That is, at this time, the light entering the low refractive index layer 102 from the flat portion 122A of the convex portion 122 and heading from the low refractive index layer 102 to the side surface 120S is not totally reflected by the side surface 120S, but is partially reflected. Part is refracted and transmitted. At this time, the reflected light gathers in the front view direction and an angle range close to this. On the other hand, the light that does not enter the low refractive index layer 102 from the flat portion 122A of the convex portion 122 and goes from the side surface 120S to the low refractive index layer 102 side is totally reflected by the side surface 120S and the angle on the high angle side. Gather in the range. As a result, the color change of the light in the angle range on the high angle side with respect to the color of the light projected in the front view direction is suppressed. On the other hand, the flat portions 121A and 122A of the concave-convex shape 120 have a function of transmitting light vertically incident on the optical structure 100 in the front direction. As a result, in the present embodiment, the diffusion of the light emitted to the front side is suppressed, and the display quality in the front view is maintained well. At this time, as described above, the light reflected by the side surface 120S and collected in the front view direction and the angle range close to this is not greatly diffused, so that the display quality in the front view is not affected. ..

As described above, in the present embodiment, while maintaining good display quality in the front view of the display device 10, good display quality is locally obtained in a part of the angle range on the high angle side within the viewing angle. You will be able to get it.

Hereinafter, the preferable conditions of the uneven shape 120 will be described in detail with reference to FIG. 4, reference numeral θ1 denotes the minimum angle of the side surface 120S of the uneven shape 120 makes with the normal line direction _{d 3} of the low refractive index layer 102 and the high-refractive index layer 103, reference numeral θ2 is the side 120S of the irregularities 120 It indicates the maximum angle formed between the normal direction d ₃ of the low refractive index layer 102 and the high-refractive index layer 103. Specifically, the minimum angle θ1, the angle (narrow angle of the tangent through the concave portion 121 side of the end point of the side surface 120S constituting the normal direction d ₃ of the low refractive index layer 102 and the high-refractive index layer 103, those causing other words acute angle a angle), the maximum angle θ2, the angle (narrow angle of the tangent passing through the convex portion 122 side of the end point of the side surface 120S constituting the normal direction d ₃ of the low refractive index layer 102 and the high-refractive index layer 103, in other words The angle that becomes the sharp angle). When the side surface 120S is a bent surface, the minimum angle θ1 is such that the straight line passing through the element surface including the end point on the recess 121 side of the side surface 120S is the normal direction d of the interface between the low refractive index layer 102 and the high refractive index layer 103. ₃ becomes the angle, the maximum angle θ2 is the angle which the straight line passing through the element surface including the end point of the convex portion 122 side of the lateral surface 120S makes with the normal line direction d ₃ of the interface of the low refractive index layer 102 and the high-refractive index layer 103 It becomes. The code θ0 is a straight line connecting the end points of the side surface 120S of the irregularities, "average slope angle" of the side surface 120S which is defined as the normal direction d ₃ of the low refractive index layer 102 and the high-refractive index layer 103, a Is shown. The average slope angles, the straight line connecting the end points of the side surface 120S of irregular shape, narrow angle of the angle formed by the normal direction d _3, an angle of the direction of the other words acute angle. Further, the reference numeral P indicates a pitch which is an interval of one cycle between one concave portion 121 and the convex portion 122 in the concave-convex shape 120. Further, reference numeral H indicates the height of the concave-convex shape 120 along the normal direction from the concave portion 121 to the convex portion 122, and reference numeral L indicates a distance in the surface direction between both end points of the side surface 120S. The above angles and the like are directions on the main surface of the optical structure 100 that are orthogonal to the second direction d ₂ , that is, angles and the like on the surface including the first direction d ₁ and the normal direction d ₃ .

The inventor of the present invention has found that the above-mentioned "average slope angle θ0" is preferably 11 degrees or more and 17 degrees or less. When the average slope angle θ0 is set in the range of 11 degrees or more and 17 degrees or less in this way, in the experiment and simulation of the present inventor, the flat portion 122A of the convex portion 122 enters the low refractive index layer 102 and has low refractive index. A part of the light from the rate layer 102 toward the side surface 120S is reflected by the side surface 120S and tends to be particularly easily collected in the front view direction and an angle range close to this, and the light directed from the side surface 120S toward the low refractive index layer 102 side is It was found that the side surface 120S is totally reflected and easily gathers in the angle range on the high angle side, particularly in the range of 60 degrees or more and 70 degrees or less. Therefore, when the average slope angle θ0 is set within the above angle range, the color change within the viewing angle with respect to the color of the light projected in the front view direction is observed in a part of the angle range on the high angle side. It becomes possible to suppress it locally and particularly effectively.

Further, the "slope angle range α" is defined by the difference between the maximum angle θ2 and the minimum angle θ1. As a result of diligent research, the present inventor has found that when the above-mentioned average slope angle θ0 is 11 degrees or more and 17 degrees or less, the slope angle range α is preferably 14 degrees or more and 18 degrees or less. Specifically, as a result of diligent research, the present inventor set the slope angle range α within a relatively narrow range when the slope angle range α is 14 degrees or more and 18 degrees or less, so that the height within the viewing angle is high. By making it possible to effectively disperse light in this angle range while collecting light in a part of the angle range on the angle side, for example, when red, blue, or green light is projected, the angle is concerned. It has been found that the ratio of the intensity of these lights in the range can be leveled, and as a result, the color change of the light in the angle range on the high angle side with respect to the color of the light projected in the front view direction can be effectively suppressed.

Further, the present inventor refers to the ratio β of the total length of the flat portions 121A and 122A to the length of one cycle of the concave portion 121 and the convex portion 122 of the concave-convex shape 120, that is, FIG. 4, β = (a + b). It was also found that / P is preferably 0.60 or more and 0.90 or less, and particularly preferably 0.75 or more and 0.85 or less. The a is the width (length) of the flat portion 122A of the convex portion 122, and the b is the width (length) of the flat portion 121A of the concave portion 121. In a general liquid crystal panel, the light traveling in the front view direction is controlled to an optimum state so that the display quality in the front view direction is good. Therefore, when a member such as the optical structure 100 is provided. However, it is desirable to make effective use of such light. If the ratio β is excessively small, that is, if the ratios of the flat portions 121A and 122A are excessively small, the light traveling in the front view direction controlled by the liquid crystal panel in the optimum state cannot be effectively utilized, and the display quality is displayed by the optical structure 100. May be undesirably damaged. Therefore, the present inventor has set the range of the ratio β as a preferable numerical value as a setting that can sufficiently secure the flat portions 121A and 122A while sufficiently obtaining the optical action of the side surface 120S.

In the concave-convex shape 120, especially when the average slope angle θ0 is 11 degrees or more and 17 degrees or less, the slope angle range α is 14 degrees or more and 18 degrees or less, and the ratio β is 0.75 or more and 0.85 or less. While effectively maintaining good display quality in the front view of the display device 10, it is possible to locally obtain good display quality (color change suppressing effect) in a part of the angle range on the high angle side within the viewing angle. Can be done. However, the concave-convex shape 120 is useful even when only a part of the above-mentioned three kinds of dimensional conditions is satisfied.

The average slope angle θ0, the minimum angle θ1 and the maximum angle θ2 used to obtain the slope angle range α, the width a of the flat portion 121A of the concave portion 121 used to obtain the ratio β, and the flat portion 122A of the convex portion 122. The width b and the like can be specified, for example, by imaging and evaluating an SEM image of a cross section when the optical structure 100 is cut in the thickness direction, that is, an SEM image corresponding to the cross section shown in FIG.

Further, the above-mentioned three types of dimensional conditions, that is, the average slope angle θ0 is 11 degrees or more and 17 degrees or less, the slope angle range α is 14 degrees or more and 18 degrees or less, and the ratio β is 0.75 or more and 0.85. In the following cases, by adjusting the refractive index of the low refractive index layer 102 and the high refractive index layer 103, the color of the light projected in the front view direction is inclined with respect to the front view direction. The color change Δu'v'of the projected light gradually increases from the front view direction to the tendency change angle set between 40 degrees and 55 degrees with respect to the front view direction, and decreases after the tendency change angle. It is possible to form a characteristic that turns into a tendency.

More specifically, the light projected from the display surface 15A of the display device 10 (liquid crystal panel 15) to the outside through the optical structure 100 is directed to the normal direction d of the low refractive index layer 102 and the high refractive index layer 103. ₃ and the front view direction of the parallel display device 10, when observed from the direction inclined with respect to the front view direction in the front view direction and the first plane including the direction d _1, projected to the front view direction The tendency change Δu'v'of the light projected in the inclined direction with respect to the color of the light to be set is set between 40 degrees and 55 degrees or less with respect to the front view direction from the front view direction. It is possible to form a characteristic that gradually increases up to the angle and turns to a decreasing tendency after the tendency change angle. When such a characteristic occurs, the color change within the viewing angle with respect to the color of the light projected in the front view direction can be effectively suppressed locally in a part of the angle range on the high angle side. It can be said that. The tendency change angle means an angle at which a maximum value of the color change Δu'v'of the light projected in the inclined direction occurs with respect to the color of the light projected in the front view direction.

The color change Δu'v'indicates a color difference, and in the present embodiment, the smaller the value, the smaller the color difference with respect to the light projected in the front view direction. The color change Δu'v'is calculated from the colors defined by u'and v'in the uniform color space. The value of Δu'v'at an angle θ in a certain viewing angle is expressed by the following equation (1).

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

Here, in each of the above equations, x and y are the color coordinates defined by the CIE 1931 color space (CIE xyY color space).

The above-mentioned characteristic of the color change Δu'v'is basically generated by any light projected from the display surface 15A of the display device 10 (liquid crystal panel 15), but in the present embodiment, the optical As the main body (liquid crystal panel 15) of the display device provided with the structure 100, a multi-domain type VA type liquid crystal display device manufactured by SONY was used, and the characteristics of the color change Δu'v'were confirmed. More specifically, the optical structure 100 is attached to the main body of the display device, a blue image is displayed by the pattern generator, and the color change when the blue image is projected to the outside through the optical structure 100 is measured by Topcon's “Spectroscopy”. Evaluation was performed using a radiometer SR-2.

Further, when the above-mentioned three types of dimensional conditions are satisfied, basically, the tendency change angle (change point to the decreasing tendency, that is, the change point to the decreasing tendency) of the light projected from the display surface 15A to the outside through the optical structure 100 is satisfied. The color change Δu'v'at the maximum value) is the color change Δu'v at an angle corresponding to the tendency change angle of the light projected to the outside from the display surface 15A of the display device 10 without passing through the optical structure 100. Another characteristic is that the value is smaller than'. When such further characteristics occur, the optical structure causes a color change Δu'v'in a predetermined angle range on the side higher than the tendency change angle of the light projected to the outside through the optical structure 100. Compared with the case where 100 is not provided, it is possible to significantly suppress the color change on the high angle side.

Further, under the above-mentioned three types of dimensional conditions, the optical structure 100 is formed from the display surface 15A of the display device 10 in a range of 60 degrees or more and 70 degrees or less with respect to the front view direction of the display device 10 by appropriate dimensional adjustment. Each value of the color change Δu'v'of the light projected to the outside via the display device 10 corresponds to each value of the light projected to the outside from the display surface 15A of the display device 10 without passing through the optical structure 100. It can also be set to less than half of the value of the color change Δu'v'at the position. In this case, a remarkable color change suppressing effect can be obtained so that the observer can easily perceive the color change Δu'v'in a predetermined angle range on the high angle side.

Further, the ratio a: b of the width a of the flat portion 122A of the convex portion 122 to the width b of the flat portion 121A of the concave portion 121 is preferably in the range of 1: 6 to 3: 1. According to the diligent research of the present inventor, by setting a: b in the range of 1: 6 to 3: 1 in the range of the ratio β of 0.75 or more and 0.85 or less, the side surface 120S makes a high angle. It has been found that light can be incident into the low refractive index layer 102 from the flat portion 122A of the convex portion 122 to such an extent that the color change on the side can be sufficiently suppressed.

Note the thickness in the normal direction _{d 3} layer body 102A in the low refractive index layer 102 is, for example, 0.5μm or more 30μm or less. The thickness in the normal direction _{d 3} of the lens unit 110 in the low-refractive index layer 102 (height) is, for example, 1.0μm or more 30μm or less. The refractive index of the low refractive index layer 102 is, for example, 1.40 or more and 1.55 or less. On the other hand, the thickness in the normal direction _{d 3} of the high refractive index layer 103 from the flat portion 122A of the projection 122 to the surface of the liquid crystal panel 15 side of the high refractive index layer 103 is 5μm or more 100μm or less. The refractive index of the high refractive index layer 103 is, for example, 1.55 or more and 1.90 or less, which is larger than the refractive index of the low refractive index layer 102.

Here, in the graph of FIG. 5, the color change Δu'v'in the viewing angle of the display device 10 provided with the optical structure 100 according to the present embodiment under a predetermined condition and the optical structure 100 are attached. The color change Δu'v'in the viewing angle of the display device 10 that is not displayed is shown. The color change Δu'v'of the display device 10 to which the optical structure 100 is not attached is the light projected from the display surface 15A of the display device 10 to the outside without passing through the optical structure 100 in the front view direction. It is the color change (color difference) of the light color when viewed from an oblique direction with respect to the light color. More particularly, the color change Δu'v within the field of view angle of the display device 10 having the optical structure 100 according to the embodiment in FIG 5 'is in the second direction d ₂ in the main surface of the optical structure 100 The color of the light in the front view direction when the light is visually recognized in the direction inclined with respect to the front view direction on the surface including the orthogonal direction, that is, the first direction d ₁ and the normal direction d _3. It is the color change for. Further, the color change Δu'v'in the viewing angle of the display device 10 to which the optical structure 100 is not attached is a direction orthogonal to the second direction d ₂ on the main surface of the optical structure 100, that is, the first direction d _1. When, in the normal direction d ₃ and the color of light at the time of viewing the light at an oblique direction with respect to the front view direction keep surface corresponding to the plane containing the, that color change with respect to the color of the front view direction of the light Is.

In the example of FIG. 5, after setting the following conditions, the color change Δu'v'of the light projected to the outside through the optical structure 100 and the light projected to the outside without passing through the optical structure 100. The color change Δu'v'of light was evaluated using a "spectroradiometer SR-2" manufactured by Topcon.

(Conditions for Optical Structure 100)
-Shape of side surface 120S: Curved surface convex toward the high refractive index layer 103 side-Average slope angle θ0: 12.0 degrees-Slope angle range α: 15.0 degrees (minimum angle θ1: 5 degrees, maximum angle θ2: 20 degrees) )
・ Ratio β: 0.79

The dimensions and physical properties of each layer of the optical structure 100 are as follows.
The thickness of the layer body 102A of the low refractive index layer 102 is 4 μm, the thickness of the lens portion 110 is 16 μm, and the refractive index is 1.48.
The thickness of the high refractive index layer 103 from the flat portion 122A of the convex portion 122 to the surface of the high refractive index layer 103 on the liquid crystal panel 15 side is 45 μm, and the refractive index is 1.65.
The thickness of the base material 101 is 70 μm, and its refractive index is 1.49.
The thickness of the antireflection layer 104 is 12 μm, and its refractive index is 1.35.

(Light projected from the display surface 15A)
-Main body of the display device (liquid crystal panel 15) provided with the optical structure 100: Multi-domain type VA type liquid crystal display device manufactured by Sony Corporation-Projected light: Blue image

In FIG. 5, the line L1 shows the color change Δu'v'in the viewing angle of the display device 10 provided with the optical structure 100, and the line L2 shows the field of view of the display device 10 without the optical structure 100 attached. The color change Δu'v'in the angle is shown. As is clear from the comparison between the line L1 and the line L2, the color change Δu'v'in the viewing angle of the display device 10 provided with the optical structure 100 is suppressed as compared with the case where the optical structure 100 is not attached. In particular, it is remarkably suppressed in a range of angles larger than the tendency change angle CA. In the color change Δu'v'in the viewing angle of the display device 10 provided with the optical structure 100 shown in FIG. 5, the above-mentioned tendency change angle CA is set to 48 degrees in the viewing angle. Each value of the color change Δu'v'projected to the outside through the optical structure 100 in the range of 60 degrees or more and 70 degrees or less within the viewing angle is the light projected to the outside without passing through the optical structure 100. It is less than half of the value of the color change Δu'v'at the position corresponding to each of the above values. In the visual confirmation, no color difference was detected between the light projected in the front view direction through the optical structure 100 and the light projected in the front view direction without passing through the optical structure 100. ..

From the results of FIG. 5 as described above, the optical structure 100 maintains a good display quality in the front view of the display device 10, and a part of the angle range on the high angle side within the viewing angle, particularly 60. It was confirmed that good display quality can be locally obtained in an angle range of 1 degree or more and 70 degrees or less.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and further modifications can be made to these embodiments. For example, in the above-described embodiment, the surface light source device 20 is of the edge light type, but the surface light source device 20 may be of the direct type.

Further, in the above-described embodiment, the optical structure 100 is attached to the upper polarizing plate 13 of the liquid crystal panel 15. At this time, the optical structure 100 may be attached to the upper polarizing plate 13 integrated with the liquid crystal panel 15, or may be attached to the upper polarizing plate 13 before being integrated with the liquid crystal panel 15. Good. That is, the polarizing plate with an optical structure in which the upper polarizing plate 13 and the optical structure 100 are integrated may be integrated in the liquid crystal layer 12 of the liquid crystal panel 15.

Further, each of FIGS. 6 to 10 shows a cross-sectional view of a modified example of the above-described embodiment. Among the components in each modification, the same components as those described in the above-described embodiment are designated by the same reference numerals, and description other than the differences will be omitted.

In the modified example shown in FIG. 6, the side surface 120S is a bent surface, and has the first element surface 131, the second element surface 132, and the third element surface 133, which are three element surfaces configured as planes, respectively. .. In the modified example shown in FIG. 7, the side surface 120S includes a curved surface 134 and a bent surface having two element surfaces 135 and 136 configured as a flat surface. In the modified example shown in FIG. 8, the side surface 120S includes a curved surface 137 and a flat surface 138.

Further, in the modified example of FIG. 9, a flat layer 105 is provided between the base material 101 and the low refractive index layer 102. The flat layer 105 is a layer interposed between the low refractive index layer 102 and the base material 101 to stabilize the bonded state between the low refractive index layer 102 and the base material 101. The flat layer 105 is made of a transparent material having light transmission, and particularly in the present embodiment, is made of a material capable of transmitting visible light and ultraviolet rays, and is mainly composed of, for example, polyester resin, vinyl chloride / vinyl acetate resin, urethane resin, or the like. May be included as. The flat layer 105 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 105 is, for example, 1 μm or more and 20 μm or less. The refractive index of the flat layer 105 is, for example, 1.46 or more and 1.1.67 or less.

Further, in the modified example of FIG. 10, the positional relationship between the low refractive index layer 102 and the high refractive index layer 103 is interchanged with that of the above-described embodiment. That is, the low refractive index layer 102 is arranged closer to the liquid crystal panel 15 than the high refractive index layer 103. The side surface 120S is a curved surface or a bent surface that is convex toward the low refractive index layer 102, or a surface that includes at least one curved surface that is convex toward the low refractive index layer 102 and at least one flat surface. In the illustrated example, the curved surface is convex toward the low refractive index layer 102 side. The dimensions and physical properties of the low refractive index layer 102, the high refractive index layer 103, the base material 101, and the antireflection layer 104 are set in the same manner as in the above-described embodiment.

In the modified example shown in FIG. 10, the light incident on the optical structure 100 from the liquid crystal panel 15 side shown in FIG. 2 is imparted with an optical action by the concave-convex shape 120. Specifically, at this time, the light incident from the flat portion 122A of the convex portion 122 and traveling on the high angle side of the viewing angle toward the curved side surface 120S which is convex toward the low refractive index layer 102 side is totally reflected by the side surface 120S. The light is diffused over a wide range in the direction including the low angle side, and the light vertically incident on the optical structure 100 is advanced in the front direction by the flat portions 121A and 122A of the concave-convex shape 120, and the diffusion is suppressed. As a result, the color change within the viewing angle is suppressed, and the decrease in brightness and contrast in the front view is suppressed.

With respect to the slope angle range α, the average slope angle θ0, and the ratio β of the total length of the flat portions 121A and 122A to the length of the concave portion 121 and the convex portion 122 of the concave-convex shape 120 for one cycle described with reference to FIG. In the modified example shown in FIG. 10, the slope angle range α is preferably 3 degrees or more and 60 degrees or less. The larger the slope angle range α, the more the light can be dispersed, and it is better that it is 20 degrees or more, more preferably 30 degrees or more, and further preferably 40 degrees or more. Further, the average slope angle θ0 is preferably 9 degrees or more and 18 degrees or less. Further, the ratio β, that is, referring to FIG. 4, β = (a + b) / P is particularly preferably 0.60 or more and 0.90 or less.

Considering the ease of die cutting, the larger the ratio β, the easier the die cutting. Considering such manufacturing merits, the ratio β is preferably 0.50 or more and less than 1.00, and considering that it is easy to secure the effect of suppressing color change, it is 0.60. It is more preferably less than 0.90.

The concave-convex shape 120 is formed so as to satisfy the above-mentioned three types of dimensional conditions at the same time, so that the display quality in the front view of the display device is kept good and the color change within the viewing angle is extremely effective. It will be possible to suppress it. However, even when only a part of the above-mentioned dimensional conditions is satisfied, the uneven shape 120 can effectively suppress the color change within the viewing angle.

The reason why it is desirable to set the dimensions of the concave-convex shape 120 described above is described in Japanese Patent Application Laid-Open No. 2018-180415 (filed on April 19, 2017, Japanese Patent Application No. 2017-82978) previously filed by the applicant. All contents of Japanese Patent Application No. 2017-82978 shall be incorporated by reference in this application. Further, by providing the antireflection layer 104, the decrease in brightness is suppressed, and the display quality within the viewing angle can be effectively improved in the absence of the antireflection layer 104.

FIG. 11 schematically shows the configuration of the display device 210 according to the modified example. The display device 210 is configured by laminating an organic LED (Organic Light Emitting Diode) panel 215, an optical structure 300, a circular polarizing plate 220, a touch panel 230, and a cover glass 240 in this order. The optical structure 300 is arranged on the display surface (surface) 215A of the organic LED panel 215. The front surface of the optical structure 300 and the back surface of the circularly polarizing plate 220 are bonded by the first adhesive layer 251. The front surface of the circularly polarizing plate 220 and the back surface of the touch panel 230 are bonded by the second adhesive layer 252, and the front surface and the cover of the touch panel 230. The back surface of the glass 240 is bonded with a third adhesive layer 253. Each of the adhesive layers 251 to 253 is so-called OCA (Optical Clear Adhesive) and has a high light transmittance. In this example, the organic LED panel 215 and the optical structure 300 are not bonded by the adhesive layer, but these may also be bonded by the adhesive layer.

Generally, in an organic LED panel, a blue shift is likely to occur in an image viewed from an angle. The blue shift is a phenomenon in which an image viewed in an oblique direction has a stronger blue color than an image viewed in a front view. That is, in the image displayed by the organic LED panel, the color tone may change significantly between the front view and the oblique direction view. Such a blue shift tends to be particularly noticeable in an organic LED panel that employs a microcavity structure. Therefore, in the display device 210, the optical structure 300 is used to suppress the color change within the viewing angle. The display device 210 of this example adopts a microcavity structure, but may be of another type.

The optical structure 300 of this example includes a low refractive index layer 302 and a high refractive index layer 303 bonded to each other. Although the base material is not arranged on the side of the low refractive index layer 302 opposite to the high refractive index layer 303 side, a base material may be contained.

FIG. 12 is a perspective view of the optical structure 300, and the high refractive index layer 303 is shown by a chain double-dashed line for convenience of explanation. As shown in FIG. 12, the low refractive index layer 302 integrally includes a film-shaped layer body 302A and a plurality of lens portions 310 two-dimensionally arranged on the back surface of the layer body 302A. On the other hand, the high refractive index layer 303 is laminated on the low refractive index layer 302 so as to cover the lens portion 310 and fill the space between the plurality of lens portions 310. As a result, in the present embodiment, the interface between the low refractive index layer 302 and the high refractive index layer 303 has an uneven shape. The high refractive index layer 303 is in the form of a film having a plurality of holes for accommodating the plurality of lens portions 310. The low refractive index layer 302 may be composed of a set of a plurality of lens units 310 without having the layer body 302A.

FIG. 13A is a view of the low refractive index layer 302 viewed in the normal direction thereof, and is a diagram showing the arrangement of the lens portions 310. In this example, as shown in FIGS. 12 and 13 (A), the lens portions 310 are two-dimensionally arranged in a matrix. Specifically, rows formed by a plurality of lens units 310 arranged at equal intervals in the first direction d ₁ are arranged at equal intervals in the second direction d ₂ . The first direction d ₁ referred to in this example corresponds to the left-right direction of the image when the image displayed by the display device 210 is visually recognized from the front view, and the second direction d ₂ corresponds to the vertical direction of the image. Further, the lens portions 310 may be arranged two-dimensionally in a houndstooth pattern as shown in FIG. 13 (B). The plurality of lens units 310 may include a plurality of lens units 310 arranged in a matrix and a plurality of lens units 310 arranged in a houndstooth pattern.

Further, as shown in FIG. 11, the lens portion 310 of this example has a tapered column shape, and extends to the tip of the high refractive index layer 303 side along the plane direction of the low refractive index layer 102 and the high refractive index layer 103. It has a flat portion 311. The flat portion 311 has a rectangular shape, and more specifically, a square shape. On the other hand, the lens portion 310 has four side surfaces 310S located between the flat portion 311 and the layer body 302A and connected so as to form a rectangular shape.

Two sides 310S facing in the first direction _{d 1} across the flat portion 311 has a tapered high refractive index layer 303 side. Although not shown, it has a tapered two sides 310S also high refractive index layer 303 side facing the flat portion 311 sandwiched therebetween the second direction d _2. Further, each of the four side surfaces 310S has a curved surface that is convex toward the high refractive index layer 103 side. However, each side surface 310S may be a bent surface that is convex toward the high refractive index layer 103 side, or may be a flat surface.

The circular polarizing plate 220 has a polarizer and a retardation plate, the retardation plate is arranged on the organic LED panel 215 side, and the polarizer is a surface of the retardation plate opposite to the organic LED panel 215 side. It is joined to. Specifically, the polarizer is a linear polarizer, and the retardation plate is a λ / 4 retardation plate. The touch panel 230 includes a transparent glass plate, and it is desirable that the touch panel 230 adopts a capacitance method. Although the cover glass 240 has a protective function, it may have other functions such as an antireflection function.

In the display device 210 described above, the circular polarizing plate 220 is arranged on the external light incident side (cover glass 240 side) of the optical structure 300, so that the external light is directed from the cover glass 240 toward the organic LED panel 215. Is incident, the circular polarizing plate 220 makes it difficult for external light to enter the optical structure 300, and multiple reflections in the optical structure 300 can be suppressed. As a result, the occurrence of visibility obstruction events such as rainbow unevenness and interference fringes is suppressed, and good visibility of the image can be ensured.

In the display device 210 described with reference to FIGS. 11 to 13, the lens portion 310 in the low refractive index layer 302 has a quadrangular pyramid shape, but may have a conical shape shown in FIG. Further, the arrangement may be in a matrix shape as shown in FIG. 14 (A) or in a houndstooth shape as shown in FIG. 14 (B). Further, the lens unit 310 may have a triangular pyramid shape, a hexagonal pyramid shape, or an octagonal pyramid shape.

Further, when the lens unit 310 is viewed in the normal direction of the low refractive index layer 302, the aspect ratio of the lens unit 310 shown in FIG. 13 (A) (first maximum width W1: direction in which the first maximum width W is defined). The second maximum width W2) in the direction orthogonal to is preferably about 1: 3 to 3: 1. If the difference between the first maximum width W1 and the second maximum width W2 is larger than three times, the productivity is lowered due to the difficulty in die cutting, and the risk of collapse of the lens portion 310 is high. The direction defining a direction or a second maximum width W2 defining a first maximum width W1, it is good is parallel to the first direction d _1.

Further, the display device 210 includes a combination of the organic LED panel 215 and the optical structure 300 in which the lens unit 310 has a two-dimensional arrangement, but instead of the optical structure 300, the above embodiment The optical structure 100 described in the above may be adopted. Further, the display device may be configured by combining the optical structure 100 shown in FIG. 10 and the organic LED panel 215.

Further, when assembling the display device 210, a polarizing plate with an optical structure in which the optical structure 300 and the circular polarizing plate 220 are integrated may be produced in advance. In this case, the low refractive index layer 302 of the optical structure 300 and the retardation plate of the circular polarizing plate 220 are bonded together.

10 ... Display device, 12 ... Liquid crystal layer, 13 ... Upper polarizing plate, 14 ... Lower polarizing plate, 15 ... Liquid crystal panel, 15A ... Display surface, 15B ... Back surface, 20 ... Surface light source device, 21 ... Light emitting surface, 24 ... Light source , 28 ... Reflective sheet, 30 ... Light guide plate, 31 ... Light emitting surface, 32 ... Back surface, 33 ... Incoming surface, 34 ... Opposite surface, 37 ... Inclined surface, 38 ... Step surface, 39 ... Connecting surface, 60 ... Optical sheet , 65 ... Main body, 67 ... Incoming side surface, 70 ... Unit prism, 100 ... Optical structure, 101 ... Base material, 101A ... Light emitting surface, 101B ... Back surface, 102 ... Low polarizing layer, 102A ... Layer main body, 103 ... High refractive index layer, 104 ... Antireflection layer, 110 ... Lens part, 120 ... Concavo-convex shape, 120S ... Side surface, 121 ... Concave, 121A ... Flat part, 122 ... Convex part, 122A ... Flat part, 210 ... Display device, 215 ... Organic LED panel, 215A ... Display surface, 220 ... Circularly polarizing plate, 230 ... Touch panel, 240 ... Cover glass, 251 ... First adhesive layer, 252 ... Second adhesive layer, 253 ... Third adhesive layer, 300 ... Optical Structure, 302 ... low refractive index layer, 302A ... layer body, 303 ... high refractive index layer, 310 ... lens unit, 310S ... side surface, 311 ... flat portion, SL ... reference line, d ₁ ... first direction, d ₂ … Second direction, d ₃ … normal direction

Claims (17)

An optical structure arranged on the display surface of a display device.
Low refractive index layer and
A high refractive index layer laminated on the low refractive index layer and having a higher refractive index than the low refractive index layer is provided.
The interface between the low refractive index layer and the high refractive index layer has an uneven shape.
The concave portions and convex portions forming the uneven shape are alternately arranged in the first direction parallel to the main surface of the sheet-shaped low refractive index layer and the high refractive index layer, and are parallel to the main surface and in the first direction. Extends linearly along the intersecting second direction
Each of the concave portion and the convex portion has a flat portion extending along the plane direction of the low refractive index layer and the high refractive index layer.
The concave portion is a portion recessed toward the low refractive index layer side, the convex portion is a portion convex toward the high refractive index layer side, and is between the flat portion of the concave portion and the flat portion of the convex portion. The uneven side surface is formed,
The two side surfaces of the concave-convex shape that are adjacent to each other with the flat portion of the concave portion interposed therebetween form a tapered shape from the high refractive index layer side toward the low refractive index layer side, and sandwich the flat portion of the convex portion. The two side surfaces of the concavo-convex shape adjacent to each other form a tapered shape from the low refractive index layer side toward the high refractive index layer side.
An optical structure in which the high refractive index layer is arranged so as to face the display surface side of the display device. The side surface of the uneven shape is a curved surface or a bent surface that is convex toward the high refractive index layer side, or a surface that includes at least one curved surface that is convex toward the high refractive index layer side and at least one flat surface. , The optical structure according to claim 1. The average slope angle of the side surface of the uneven shape defined by the straight line connecting both end points of the side surface of the uneven shape and the normal direction of the low refractive index layer and the high refractive index layer is 11 degrees or more. The optical structure according to claim 2, which is less than or equal to the degree. The third aspect of claim 3, wherein the difference between the maximum angle and the minimum angle formed by the side surface of the uneven shape with the normal direction of the low refractive index layer and the high refractive index layer is 14 degrees or more and 18 degrees or less. Optical structure. The optics according to any one of claims 2 to 4, wherein the ratio of the total length of the flat portion to the length of the concave portion and the convex portion for one cycle is 0.75 or more and 0.85 or less. Structure. The light projected from the display surface of the display device to the outside through the optical structure is directed to the front view direction of the display device parallel to the normal direction of the low refractive index layer and the high refractive index layer. When observed from the front view direction and the direction inclined with respect to the front view direction in the plane including the first direction, the light is projected in the tilt direction with respect to the color of the light projected in the front view direction. The color change Δu'v'of light gradually increases from the front view direction to a tendency change angle set between 40 degrees and 55 degrees or less with respect to the front view direction, and decreases after the tendency change angle. The optical structure according to claim 1, which turns to. The color change Δu'v'at the tendency change angle of the light projected from the display surface to the outside through the optical structure is the light projected from the display surface to the outside without passing through the optical structure. The optical structure according to claim 6, which is smaller than the color change Δu'v'at an angle corresponding to the tendency change angle. Each value of the color change Δu'v'of the light projected from the display surface to the outside through the optical structure in the range of 60 degrees or more and 70 degrees or less with respect to the front view direction is from the display surface. The optical structure according to claim 7, wherein the value of the color change Δu'v'at a position corresponding to each value of the light projected to the outside without passing through the optical structure is half or less. Further comprising a surface material arranged on the side of the low refractive index layer opposite to the high refractive index layer side.
The optical structure according to any one of claims 1 to 8, wherein the refractive index of the surface material is 1.40 or less. The optical structure according to claim 9, wherein the surface material forms the outermost surface on the side opposite to the display surface side of the display device. Polarizing plate and
A polarizing plate with an optical structure, comprising the optical structure according to any one of claims 1 to 10 on the surface of the polarizing plate. A display device in which the optical structure according to any one of claims 1 to 10 is arranged on a display surface. The display device is
A liquid crystal panel having the display surface and a back surface arranged so as to face the display surface.
The display device according to claim 12, further comprising a surface light source device arranged to face the back surface of the liquid crystal panel. In the liquid crystal panel, when the voltage with respect to the liquid crystal molecules is off or the minimum value, the liquid crystal molecules are oriented along the normal direction of the display surface to block the light from the surface light source device, and the liquid crystal. A VA type liquid crystal configured to gradually increase the transmittance of light from the surface light source device by gradually increasing the voltage with respect to the molecules and gradually inclining the liquid crystal molecules toward the side along the display surface. The display device according to claim 13, which is a panel. With organic LED panel
Optical structure and
With a circular polarizing plate,
The optical structure includes a low refractive index layer including a plurality of lens portions and a high refractive index layer that is provided so as to fill the space between the plurality of lens portions and has a higher refractive index than the low refractive index layer. Have,
The lens portion has a columnar shape that is tapered toward the high refractive index layer side, and has a flat portion at the tip of the high refractive index layer side.
The optical structure is arranged between the organic LED panel and the circularly polarizing plate, the high refractive index layer faces the organic LED panel side, and the low refractive index layer faces the circularly polarizing plate side. A display device that faces. The display device according to claim 15, wherein the plurality of lens units are arranged two-dimensionally. Circularly polarized light and
It has a low refractive index layer including a plurality of lens portions and a high refractive index layer provided so as to fill the space between the plurality of lens portions and having a refractive index higher than that of the low refractive index layer. The lens portion includes an optical structure having a columnar shape tapered on the high refractive index layer side and a flat portion at the tip on the high refractive index layer side.
A polarizing plate with an optical structure in which the low refractive index layer and the circular polarizing plate are bonded together.