JP7130921B2 - optical structure, display device - Google Patents

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, and a display device provided with this optical structure.

Liquid crystal display devices, which are one example of display devices, are used in various fields. Liquid crystal panels of liquid crystal display devices are roughly classified into a TN (Twisted Nematic) system, a VA (Vertical Alignment) system, and an IPS (In-Plane Switching) system.

Among them, in the TN type liquid crystal panel, when the voltage is off, the liquid crystal molecules are oriented in a direction parallel to the display surface, allowing light to pass through. It has a structure in which the light transmittance is gradually lowered by rising in the direction along the line.
In the VA type liquid crystal panel, when the voltage is off, the liquid crystal molecules are oriented along the normal direction of the display surface and light is blocked, and the voltage is gradually increased to align the liquid crystal molecules along the display surface. By inclining to the side, the light transmittance is gradually increased.
The IPS type liquid crystal panel adjusts the light transmittance by rotating the liquid crystal molecules aligned along the display surface according to the application of voltage.

In liquid crystal panels, control of the amount and range of light traveling to the front side is usually regarded as important, and measures are taken to ensure suitable brightness, contrast ratio, and color reproducibility when viewed from the front.
On the other hand, it is relatively complicated to control light traveling in a direction that is inclined with respect to the normal direction of the liquid crystal panel. In order to sufficiently suppress the noise, the structure becomes complicated, which undesirably increases the cost.
In order to address such a problem, for example, Patent Documents 1 to 4 disclose optical members provided on the display surface of the liquid crystal panel in order to widen the viewing angle by the action of diffusion or the like. With such a member, it is possible to easily improve the viewing angle.

JP-A-7-43704 Patent No. 3272833 Patent No. 3621959 JP 2016-126350 A

In a liquid crystal panel that employs the VA method among the above methods, when viewed from a direction that is tilted with respect to the normal line of the display surface, the shape of the emission spectrum in that tilt direction changes, resulting in color reproduction. A decrease in degree occurs.
The reason for this is that the change in the shape of the emission spectrum with respect to the viewing angle for blue display is strong (compared to red display and green display). The inventors of the present invention have found that the display color tends to yellow due to a change that increases with respect to the "intensity of the wavelength component to be generated". It would be useful if this problem could be solved by an optical member as described above. However, it is difficult to say that the above-described conventional technology is devised to effectively suppress the color change according to the viewing angle.

An object of the present invention is to improve the color reproducibility and color gradation expression within the viewing angle while maintaining good display quality when viewed from the front of the display device. It is an object of the present invention to provide an optical structure and a display device having the same.

The present invention solves the above problems by means of the following solutions. In order to facilitate understanding, reference numerals corresponding to the embodiments of the present invention are used for explanation, but the present invention is not limited to these.
A first invention is an optical structure arranged on the light exit side of a display surface (15A) of a display device (10), comprising a substrate layer (101) and a first optical structure laminated on the substrate layer. A layer (105) and a plurality of layers arranged in one direction along the surface of the first layer opposite to the base layer side, extending in a direction intersecting the arrangement direction, and the base layer and a second layer (103) laminated so as to fill the uneven shape of the first layer and the lens portion, wherein the first A plurality of layers are arranged along the surface opposite to the base layer side, along the arrangement direction of the lens parts, extend in a direction intersecting the arrangement direction, and extend in the direction crossing the arrangement direction, and a second lens portion (130) convex to the opposite side, and the interface between the second lens portion and the lens portion and the interface between the lens portion and the second layer have a difference in refractive index. An optical structure (100) characterized by:
In a second aspect of the invention, in the optical structure of the first aspect, in a cross section parallel to the thickness direction of the optical structure and the arrangement direction of the lens portions, the second lens portion (130) is the lens portion ( 110).
A third invention is the optical structure according to the first or second invention, wherein the refractive index of the lens portion (110) is the refractive index of the first layer (105) and the second layer (103). and the refractive index of the first layer is lower than the refractive index of the lens portion and higher than the refractive index of the base layer (101) and the second layer. A structure (100).
A fourth invention is the optical structure according to any one of the first to third inventions, wherein the lens section (110) has a cross-sectional shape in the thickness direction of the optical structure and in the arrangement direction of the lens sections, An optical structure (100) characterized by being trapezoidal.
A fifth aspect of the present invention is the optical structure according to any one of the first to fourth aspects, wherein the second lens portion (130) has a The optical structure (100) is characterized in that the cross-sectional shape thereof is a curvilinear shape convex toward the second layer (103).
A sixth invention is a display device (10) comprising the optical structure (100) according to any one of the first to fifth inventions on the light output side of the display surface (15A).
A seventh invention is based on the display device of the sixth invention, comprising: a liquid crystal panel (15) having the display surface (15A); A display device (10) comprising: a device (20).
In an eighth aspect based on the display device of the seventh aspect, the liquid crystal panel (15) has the liquid crystal molecules oriented along the normal direction of the display surface when the voltage applied to the liquid crystal molecules is off or at a minimum value. Then, the light from the surface light source device is blocked, and the surface light source device (20 A display device (10) characterized by being a VA type liquid crystal panel configured to gradually increase the transmittance of light from (10).
A ninth aspect of the invention is based on the display device according to any one of the sixth to eighth aspects, wherein the optical structure (100) includes the base layer (101) on the light exit side and the second layer (103) on the light exit side. on the side of the display surface (15A).

According to the present invention, it is possible to improve the color reproducibility within the viewing angle and the color gradation representation while maintaining good display quality in the front view of the display device.

1 is a schematic cross-sectional view of a display device 10 of an embodiment; FIG. 3 is a schematic cross-sectional view of the display device 10 for explaining behavior of light in the display device 10 of the embodiment; FIG. 1 is an enlarged cross-sectional view of an optical structure 100 of an embodiment; FIG. 4 is a further enlarged view of the enlarged cross-sectional view of the optical structure 100 of the embodiment shown in FIG. 3. FIG. FIG. 3 is a diagram illustrating light incident on a lens section 110 and a second lens section 130 in the optical structure 100 of the embodiment; It is a figure explaining an example of the manufacturing method of the optical structure 100 of embodiment. 4A and 4B are cross-sectional photographs of an optical structure 100 of an example and an optical structure 500 of a comparative example; FIG. 4 is a ray tracing diagram in the optical structure 100 of the example; FIG. 5 is a ray tracing diagram in an optical structure 500 of a comparative example; 5 is a graph showing color changes in the display device 10 of Example and the display devices of Comparative Examples 1 and 2. FIG. FIG. 5 is a diagram showing an example of a modified form of the optical structure 100; FIG. 5 is a diagram showing an example of a modified form of the optical structure 100; FIG. 5 is a diagram showing an example of a modified form of the optical structure 100; 4 is a cross-sectional photograph of an example of a modified form of the optical structure 100. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, each figure shown below including FIG. 1 is a schematic diagram, and the size and shape of each part are appropriately exaggerated for easy understanding.
In this specification, terms that specify shapes and geometric conditions, for example, terms such as parallel and orthogonal, have the same optical function and can be regarded as parallel or orthogonal in addition to the strict meaning. It shall include the state with an error of

In this specification, terms such as plate, sheet, and film are used, and as a general usage, they are used in the order of thickness, plate, sheet, and film. It is used in the specification as well. However, since there is no technical meaning in such proper use, these words can be replaced as appropriate.
Further, in this specification, the sheet surface refers to a surface of a sheet-shaped member that is in the plane direction of the sheet when viewed as a whole sheet. It is also assumed that the plate surface and the film surface are the same.

(embodiment)
FIG. 1 is a schematic cross-sectional view of a display device 10 of an embodiment.
FIG. 2 is a schematic cross-sectional view of the display device 10 for explaining behavior of light in the display device 10 of the embodiment.
FIG. 3 is an enlarged cross-sectional view of the optical structure 100 of the embodiment.
FIG. 4 is an enlarged view of the enlarged cross-sectional view of the optical structure 100 of the embodiment shown in FIG.
Note that hatching may be omitted in each of the cross-sectional views shown below, including FIGS. 1 to 4 described above, for convenience of explanation. 1 to 4, a first direction d1, which will be described later, a normal direction common to the plate surface of the liquid crystal panel 15 in the display device 10 and the sheet surface of the sheet-like base material 101 of the optical structure 100 A cross-sectional view in a plane including a second direction d2 is shown. Also, in FIG. 4, the antireflection layer 104 is omitted for convenience of explanation.
In the present embodiment, the first direction d1 is a direction parallel to the direction in which the light source 24 of the surface light source device 20 of the edge light type emits light to the light guide plate 30 in the display device 10 as will be described later. . The second direction d2 corresponds to the thickness direction of the display device 10, one of which is the viewer side and the other is the rear side.

(Display device)
First, the overall configuration of the display device 10 will be described. As shown in FIG. 1 and the like, the display device 10 of the present embodiment includes a plate-like liquid crystal panel 15, a surface light source device 20 that planarly illuminates the liquid crystal panel 15 from the rear side (light incident side), and the liquid crystal panel 15. and a sheet-like optical structure 100 arranged on the observer side (light output side) of the.
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 (sub-pixel) forming a pixel. An image is displayed on the surface 15A.

The liquid crystal panel 15 has a display surface 15A that displays a still image or a moving image on the observer side, and a back surface 15B that faces the display surface 15A.
The liquid crystal panel 15 includes a lower polarizing plate 14, a liquid crystal layer 12, and an upper polarizing plate 13 in order from the rear surface 15B side (light incident side) to the display surface 15A side (light emitting side) in the thickness direction.
The lower polarizing plate 14 and the upper polarizing plate 13 decompose the incident light into two orthogonal polarized components (for example, P wave and S wave), and linearly polarized components vibrating in one direction (direction parallel to the transmission axis). It has a function of transmitting (for example, P wave) and absorbing a linearly polarized component (for example, S wave) vibrating in the other direction (direction parallel to the absorption axis) orthogonal to the one direction.
The directions of the transmission axes of the lower polarizing plate 14 and the upper polarizing plate 13 can be appropriately set according to the liquid crystal driving method employed in the liquid crystal panel 15 and the like. In this embodiment, as will be described later, the liquid crystal panel 15 is of the VA type, and the directions of the transmission axes of the lower polarizing plate 14 and the upper polarizing plate 13 are the normal directions of the surface of the liquid crystal panel 15 (second direction d2 ) are orthogonal to each other.

In the liquid crystal layer 12, a voltage can be applied to each region forming one pixel, and the alignment direction of the liquid crystal molecules in the liquid crystal layer 12 changes depending on whether or not the voltage is applied.
As an example, the polarization component in a specific direction transmitted through the lower polarizing plate 14 rotates its polarization direction by 90° when passing through the liquid crystal layer 12 to which no voltage is applied, but the polarization direction is rotated by 90° when passing through the liquid crystal layer 12 to which voltage is applied. 12, it maintains its polarization direction. In this case, depending on whether or not a voltage is applied to the liquid crystal layer 12, the polarized component that has passed through the lower polarizing plate 14 and oscillates in a specific direction is further transmitted through the upper polarizing plate 13 arranged on the light output side of the lower polarizing plate 14. Alternatively, it is possible to control whether the light is absorbed and blocked by the upper polarizing plate 13 .
In this manner, the liquid crystal panel 15 can control transmission or blocking of light from the surface light source device 20 for each region forming a pixel.

The liquid crystal panel 15 of the present embodiment is, for example, a VA (Vertical Alignment) liquid crystal panel. Therefore, in the liquid crystal panel 15, when the voltage applied to the liquid crystal molecules in the liquid crystal layer 12 is off or at a minimum value, the liquid crystal molecules are oriented along the normal direction of the display surface 15A, and the light from the surface light source device 20 is blocked. By gradually increasing the voltage applied to the liquid crystal molecules to gradually incline the liquid crystal molecules along the display surface 15A, the transmittance of the light from the surface light source device 20 is gradually increased.
The liquid crystal driving method of the liquid crystal panel 15 is not limited to the VA method, and may be a TN (Twisted Nematic) method or an IPS (In-Plane Switching) method. Details of the liquid crystal panel 15 are described in various known documents (for example, "Flat Panel Display Comprehensive Dictionary (supervised by Tatsuo Uchida and Heiki Uchiike)" published by the Industrial Research Institute in 2001), and further details are described here. detailed description is omitted.

Next, the surface light source device 20 will be described.
The surface light source device 20 is a device that illuminates the liquid crystal panel 15 from the rear surface 15B side.
As shown in FIG. 1 and the like, the surface light source device 20 of the present embodiment is an edge light type surface light source device, and includes a light guide plate 30, a light source 24, an optical sheet (prism sheet) 60, and a reflection sheet 28. have.
In this embodiment, the surface light source device 20 will be described as an example of an edge light type.

The light source 24 is arranged laterally on one side of the light guide plate 30 (on the left side in FIGS. 1 and 2) and irradiates the light incident surface 33 of the light guide plate 30 with light.
The light source 24 of the present embodiment is composed of a large number of point-like light emitters 25 arranged side by side along the longitudinal direction of the light entrance surface 33, specifically, a large number of light emitting diodes (LEDs). there is
Note that the light source 24 is not limited to this, and may be configured in various forms such as, for example, a fluorescent lamp such as a linear cold-cathode tube, or a point-like incandescent lamp.

The light guide plate 30 is a plate-like member, and has a pair of main surfaces (a light output surface 31 and a back surface 32) and four side surfaces extending between the pair of main surfaces.
Of the pair of main surfaces of the light guide plate 30 , the main surface on the viewer side (liquid crystal panel 15 side) is the light output surface 31 , and the other main surface on the opposite side is the back surface 32 . 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, the light output surface 31 has a rectangular planar shape (the shape when viewed from the second direction d2).
Of the four side surfaces, one of the two surfaces facing in the first direction d1 is the light entrance surface 33, and the surface opposite the light entrance surface 33 is the opposite surface . The aforementioned light source 24 is provided facing the light entrance surface 33 .

The light incident on the light guide plate 30 from the light incident surface 33 is guided through the light guide plate 30 generally along the first direction (light guide direction) d1 as shown in FIG. .
The display device 10 of the present embodiment is assumed to be arranged so that the first direction d1 is along the horizontal direction, that is, the left-right direction. In this case, the light from the light source 24 is guided in the left-right direction. be. However, such an arrangement is not particularly limited, and the display device 10 may be arranged in other manners.

In this 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 rear surface 32 is inclined with respect to the plate surface of the light guide plate 30 so that the opposite surface 34 side end is located closer to the light exit surface 31 side than the light entrance surface 33 side end. a step surface 38 extending in the direction normal to the light guide plate 30; formed.
Light is guided within the light guide plate 30 by a total reflection action on the pair of main surfaces (the light exit surface 31 and the back surface 32) of the light guide plate 30. As shown in FIG. Light incident on the connection surface 39 parallel to the plate surface of the light guide plate 30 does not change its incident angle when incident on the pair of main surfaces (the light output surface 31 and the back surface 32).

However, since the inclined surface 37 is inclined so as to approach the light emitting surface 31 as it goes from the light incident surface 33 side toward the opposite surface 34 side, the light reflected by the inclined surface 37 is divided into a pair of main surfaces (light emitting surface 37). The angle of incidence when incident on the surface 31 and the back surface 32) is small. Then, the light whose incident angle to the light emitting surface 31 becomes less than the total reflection critical angle by being reflected by the inclined surface 37 is emitted from the light guide plate 30 as indicated by L1 in FIG. That is, the inclined surface 37 functions as an element for extracting light from the light guide plate 30 .
In addition, the light guide plate 30 is not limited to a form in which the back surface 32 has an uneven surface, and may have a form in which the back surface 32 has, for example, a dot pattern. In the light guide plate 30, a plurality of columnar unit optical shapes and the like are arranged on the light exit surface 31 in a direction intersecting (for example, a direction orthogonal to) the light guiding direction (first direction d1), and the light exit surface 31 is uneven. It may have a surface and control the emission direction of light in the arrangement direction of the surface.

The reflective sheet 28 is a member arranged on the back side of the light guide plate 30 so as to face the back surface 32 . The reflecting sheet 28 has a function of reflecting the light leaked from the rear surface 32 of the light guide plate 30 and making it enter the light guide plate 30 again.
The reflective sheet 28 is a member that reflects at least part of the incident light, and may be a white scattering reflective sheet, a sheet made of a material having a high reflectance such as metal, or a thin film made of a material having a high reflectance (e.g., metal). A sheet or the like containing a thin film or dielectric multilayer film as a surface layer can be used.
The reflective sheet 28 may be one that mainly reflects light regularly (specular reflection), or one that mainly diffuses and reflects light. When the reflective sheet 28 mainly diffuses and reflects light, the diffuse reflection may be isotropic diffuse reflection or anisotropic diffuse reflection.

The optical sheet 60 is arranged on the viewer side (light exit side) of the light guide plate 30 so as to face the light exit surface 31 . The optical sheet 60 is arranged to face the rear surface 32 of the liquid crystal panel 15 , and the light emitting surface 61 of the optical sheet 60 forms the light emitting surface 21 of the surface light source device 20 .
This optical sheet 60 has the function of changing the traveling direction of transmitted light, and as shown in FIG. (unit shape element, unit optical element, unit lens) 70 .

The body portion 65 is configured as a sheet-like member having a pair of parallel main surfaces. In the illustrated example, a plurality of unit prisms 70 are arranged on the light incident side surface 67 of the main body 65 along the first direction d1 (light guiding direction).
The unit prism 70 has a columnar shape, and a ridge line extends in a direction intersecting (in this embodiment, a direction orthogonal to) the arrangement direction (first direction d1).

In this embodiment, as shown in FIG. 2, parallel to the arrangement direction (first direction d1) of the unit prisms 70 and the thickness direction of the optical sheet 60 (normal direction of the sheet surface of the optical sheet 60, second direction d2) The cross-sectional shape of each unit prism 70 is a substantially triangular shape with the vertex on the back surface side, and is bent so that the surface on the opposite surface 34 side is convex. However, the cross-sectional shape of the unit prism 70 is not limited to this, and may be, for example, an isosceles triangular shape, a scalene triangular shape, or a partially curved surface. It may be selected as appropriate according to, for example.

In this embodiment, an example in which one optical sheet 60 is provided on the light exit side (liquid crystal panel 15 side) of the light guide plate 30 is shown. may be provided. In this case, the directions of the grooves of the unit prisms of each optical sheet may be different from each other.
In addition, depending on the optical performance desired for the surface light source device 20, not only the optical sheet (prism sheet) 60 described above, but also optical sheets having other optical shapes, etc. may be used on the observer side (light output side) of the optical sheet 60. ), etc., in combination as appropriate.

By providing the optical sheet 60, the surface light source device 20 emits light ( For example, the light L1 shown in FIG. 2) is directed in a desired traveling direction (parallel to the second direction d2 or in a direction forming a small angle with the second direction d2), or is converted into a desired polarization state, thereby It is possible to make it incident on the panel 15 .
Then, as described above, the light incident on the liquid crystal panel 15 is controlled in the liquid crystal layer 12 according to the voltage applied to transmit or block the light for each pixel formation region. An image is displayed at 15A.

(Optical structure)
Next, the optical structure 100 will be described.
As shown in FIGS. 2 and 3, the optical structure 100 of this embodiment includes a sheet-like base material 101, an intermediate layer 105 provided on the back side of the base material 101, and a The lens portions 110 arranged at predetermined intervals, the high refractive index layer 102 formed between the adjacent lens portions 110 on the back side of the intermediate layer 105, and the intermediate layer 105 and the lens portions 110 on the back side A low refractive index layer 103 is provided, and an antireflection layer 104 is provided on the viewer side of the substrate 101 .
The optical structure 100 of the present embodiment is arranged so that the low refractive index layer 103 faces the back side (display surface 15A side) of the display device 10, and as shown in FIG. It is in direct contact with surface 15A.

The substrate 101 is a sheet-like substrate made of a resin having optical transparency, and has a light output surface 101A and a back surface 101B arranged to face the light output surface 101A. The base material 101 uses a sheet-like member made of triacetyl cellulose (TAC).
The base material 101 has a refractive index of about 1.46 to 1.50.
The antireflection layer 104 is a layer provided on the light exit surface 101A of the substrate 101 and has a function of suppressing surface reflection of external light incident on the optical structure 100 . Accordingly, it is possible to prevent deterioration of visibility of an image displayed on the display device 10 due to surface reflection of external light. Note that the antireflection layer 104 may not be provided on the optical structure 100 depending on the environment in which the display device 10 is used, such as when the display device 10 is used in an environment where the influence of external light on the display device 10 is small.

The intermediate layer 105 is a layer provided on the back surface 101B side (back surface side) of the base material 101, and includes a layer body 105A extending along the back surface 101B and a back surface side (light incident side) of the layer body 105A. and a plurality of columnar second lens portions 130 formed in the .
As shown in FIG. 3 and the like, the second lens portion 130 has a curved cross-sectional shape that is convex toward the light incident side along the normal direction (second direction d2) of the intermediate layer 105. They are arranged at predetermined intervals along the direction d1, and the ridgeline direction extends in a direction that intersects (perpendicular to in this embodiment) the arrangement direction. The cross-sectional shape of the second lens portion 130 may be a free-form curved line, an arc shape, a partial elliptical shape, or a partial elliptical shape, as long as the cross-sectional shape of the second lens portion 130 is convex on the side opposite to the base material 101 . , a curve shape approximated to these, and various other curve shapes may be used.

The lens part 110 has a columnar shape, and in the cross section shown in FIGS. are arranged at predetermined intervals along the first direction d1.
The cross-sectional shape of the lens portion 110 shown in FIGS. 3 and 4 is a trapezoidal shape in which the dimension on the side of the substrate 101 (light exit side) is larger than the dimension on the side of the low refractive index layer 103 (light entrance side).
Further, as shown in FIGS. 3 and 4, the dimension in the direction parallel to the first direction d1 of the end portion of the lens portion 110 on the substrate 101 side is the same as the dimension of the end portion of the second lens portion 130 on the substrate 101 side. It is equal to or greater than the dimension in a direction parallel to one direction d1. Therefore, the above-described second lens section 130 is positioned on the observer side within the lens section 110 in the cross section of the optical structure 100 shown in FIG.

The high refractive index layer 102 is a layer provided between the adjacent lens portions 110 on the back side of the intermediate layer 105 . The high refractive index layer 102 is made of the same material as the lens portion 110 . In the normal direction (second direction d2) of the intermediate layer 105, the back side surface of the high refractive index layer 102 is located closer to the viewer than the back side surface of the lens portion 110 is.
Both ends of the high refractive index layer 102 in the first direction d1 may or may not be continuous with the lens portion 110 .
In addition, in the present embodiment, the optical structure 100 has a form including the high refractive index layer 102, but is not limited to this. The layer 105 may be in contact with the low refractive index layer 103 .
The low-refractive-index layer 103 is a layer laminated so as to cover the lens portions 110 and the intermediate layer 105 and fill the concave-convex shape formed by the plurality of lens portions 110 .

Thus, in the present embodiment, the interface between the low refractive index layer 103 and the high refractive index layer 102 and the interface between the low refractive index layer 103 and the lens portion 110 form the uneven shape 120 . When the optical structure 100 does not include the high refractive index layer 102 , the uneven shape 120 is formed by the interface between the low refractive index layer 103 and the intermediate layer 105 and the interface between the low refractive index layer 103 and the lens portion 110 . It is formed.

The concave-convex shape 120 has one concave portion 121 and one convex portion 122 forming a shape of one period, and is formed by repeatedly forming this one-period shape.
The portion recessed toward the intermediate layer 105 with respect to the reference line SL extending in the plane direction passing through the midpoint between the bottom of the recess 121 and the top of the protrusion 122 corresponds to the recess 121, and the low refractive index layer 103 The portion that is convex to the side corresponds to the convex portion 122 .
The concave portions 121 and the convex portions 122 are arranged in the first direction d1 and linearly extend in a direction crossing the first direction d1 (a direction orthogonal to the first direction d1 in this embodiment).

As shown in FIGS. 3 and 4, the concave portion 121 and the convex portion 122 have flat portions 121A and 122A extending along the surface directions of the intermediate layer 105 and the low refractive index layer 103, respectively.
A 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 is a curved surface convex toward the low refractive index layer 103 side. The side surface 120S is formed so as not to cross a straight line extending in the normal direction from the end point of the flat portion 121A to which the side surface 120S connects. Accordingly, when forming the lens portion 110 forming the side surface 120S, the lens portion 110 can be punched out.
The side surface 120S may be a bent surface (polygonal shape) that is convex toward the low refractive index layer 103 side, or may be a flat surface.
The uneven shape 120 as described above is displayed on the display surface 15A by exerting an optical action such as total reflection, refraction, or transmission on light for displaying an image emitted from the display surface 15A. It is provided to improve the display quality of the image.

In this embodiment, the lens part 110 and the high refractive index layer 102 have higher refractive indexes than the base material 101 , the intermediate layer 105 and the low refractive index layer 103 . The refractive indices of the lens portion 110 and the high refractive index layer 102 are preferably, for example, about 1.55 to 1.67.
The intermediate layer 105 has a refractive index lower than that of the lens portion 110 and the high refractive index layer 102 and higher than that of the low refractive index layer 103 and the base material 101 . The refractive index of the intermediate layer 105 is preferably, for example, approximately 1.49 to 1.60.
The low refractive index layer 103 has a lower refractive index than the lens portion 110 , the high refractive index layer 102 and the intermediate layer 105 . The refractive index of the low refractive index layer 103 is preferably, for example, about 1.40 to 1.52.
In the present embodiment, the lens portion 110 and the low refractive index layer 103 are selected so that their refractive index difference is in the range of 0.05 or more and 0.25 or less. The refractive index difference between the lens portion 110 and the intermediate layer 105 is selected to be 0.02 or more and 0.18 or less, and the refractive index difference between the intermediate layer 105 and the low refractive index layer 103 is 0.02. is selected to be greater than or equal to 0.15 or less.

The lens portion 110 and the high refractive index layer 102 of the present embodiment are formed of an ultraviolet curable resin having optical transparency. Further, the intermediate layer 105 is mainly composed of an ultraviolet curable resin that forms the lens portion 110, and is formed by applying this ultraviolet curable resin to the base material 101 made of TAC and dissolving the surface of the base material 101. formed by
The intermediate layer 105, the lens portion 110, and the high refractive index layer 102 are made of the same ultraviolet curable resin that has sufficient adhesion to the base material 101 made of TAC without using a primer. It is made of an ultraviolet curable resin containing a component capable of dissolving the base material 101 of.

By applying such an ultraviolet curable resin to the base material 101, the base material 101 dissolves and permeates the ultraviolet curable resin to form the intermediate layer 105, and the dissolved base material 101 does not permeate. The regions are the lens portion 110 and the high refractive index layer 102 . The formation of the intermediate layer 105 will be described later in the description of the method for manufacturing the optical structure 100 .
As such an ultraviolet-curable resin, an acrylate-based ultraviolet-curable resin containing an amide group-containing monomer, a hydroxyl group-containing monomer, or the like is suitable.

As described above, the optical structure 100 of the present embodiment has the low refractive index layer 103 on the back side (liquid crystal panel 15 side) in the thickness direction (second direction d2). In this embodiment, the low-refractive-index layer 103 is formed of a light-transmissive acrylic adhesive or the like, and as shown in FIG. It is joined to the display surface 15A.
In addition, not limited to this, the low refractive index layer 103 is formed using a resin that has light transparency and a suitable refractive index and does not have adhesiveness, and is separately applied via an adhesive layer (not shown). Alternatively, the optical structure 100 may be attached to the liquid crystal panel 15 .

Next, the uneven shape 120 will be described in more detail with reference to FIG.
In FIG. 4, the symbol θ1 indicates the minimum angle that the side surface 120S of the uneven shape 120 makes with the normal direction (d2 direction) of the base material 101, and the symbol It shows the maximum angle with the direction (d2 direction).
The minimum angle θ1 is an angle formed by a tangent line passing through the end point of the side surface 120S on the side of the recess 121 and the second direction d2. Also, the maximum angle θ2 is the angle formed by the tangent line passing through the end point of the side surface 120S on the convex portion 122 side and the second direction d2.
In addition, when the side surface 120S is a bent surface, the minimum angle θ1 is the angle formed by a straight line passing through the element surface including the end point on the recess 121 side of the side surface 120S and the second direction d2, and the maximum angle θ2 is the convexity of the side surface 120S. A straight line passing through the element surface including the end point on the portion 122 side forms an angle with the normal direction of the interface between the lens portion 110 and the low refractive index layer 103 .
Also, when the side surface 120S is flat, the minimum angle θ1 and the maximum angle θ2 are equal.

In FIG. 4, symbol θ0 indicates the “average slope angle” of the side surface 120S defined by the straight line connecting the two end points of the uneven side surface 120S and the second direction d2, which is the normal direction of the substrate 101. ing.
A symbol P indicates a pitch, which is an interval of one cycle of the unevenness composed of one concave portion 121 and one convex portion 122 in the uneven shape 120 . This is equal to the arrangement pitch of the lens section 110 and the second lens section 130 .
Symbol H indicates the height of the uneven shape 120 along the normal direction from the concave portion 121 to the convex portion 122 .

A difference between the maximum angle θ2 and the minimum angle θ1 is defined as the slope angle range α. The greater the slope angle range α, the greater the curvature of the side surface 120S. As a result of intensive research, the inventors of the present application have found that when the side surface 120S is a curved surface or a bent surface, it is preferable that the slope angle range α be 3 degrees or more and 60 degrees or less from the viewpoint of suppressing color change. . If the slope angle range α is less than 3 degrees or greater than 60 degrees, the color change becomes large when viewed from a high angle direction (a direction forming a large angle with respect to the normal direction of the display surface 15A), which is not preferable.
In addition, the inventor of the present invention also found that it is preferable from the viewpoint of suppressing color change that the average slope angle θ0 is 9 degrees or more and 18 degrees or less. When the average slope angle θ0 is less than 9 degrees or greater than 18 degrees, the color change becomes large when viewed from a high-angle direction (a direction forming a large angle with respect to the normal direction of the display surface 15A), which is not preferable. .
It is preferable that the uneven shape 120 satisfies the conditions such as the above angle range from the viewpoint of extremely effectively suppressing color change within the viewing angle while maintaining good display quality when the display device 10 is viewed from the front.

In general, the VA liquid crystal panel 15 controls the amount of backlight by changing the angle of the liquid crystal molecules. A direction forming a large angle has a small amount of light with respect to the normal direction.
In addition, since the shape of the emission spectrum of the light emitted from the VA liquid crystal panel 15 in a direction forming a large angle with respect to the front direction changes as described above, the color reproducibility deteriorates. there is
Therefore, the VA-type liquid crystal panel 15 has a large luminance change and a color change depending on the viewing angle. When observed from a different angle, the skin color appears whitish, and blue and white appear yellowish. For the reasons described above, in the VA liquid crystal panel 15, as the angle formed with the front direction (the normal direction of the display surface 15A) increases, the color gradation expression deteriorates.
The optical structure 100 and the display device 10 of the present embodiment increase the amount of light with high color reproducibility emitted in such a direction at a large angle with respect to the front direction, suppressing color change and improving gradation expression. I am planning.

FIG. 5 is a diagram illustrating light incident on the lens section 110 and the second lens section 130 in the optical structure 100 of the embodiment. In FIG. 5, the cross section of the optical structure 100 is simplified, and only the light emitting surface and back surface, the uneven shape 120 (lens portion 110), the second lens portion 130, and the like are shown.
As shown in FIG. 5, the optical structure 100 directs the light L2 emitted from the liquid crystal panel 15 in the vicinity of the front direction (normal direction of the display surface 15A) to the side surface 120S (between the lens portion 110 and the low refractive index layer 103). interface) and further at the interface between the second lens portion 130 and the lens portion 110, so that the light is directed in a direction forming a large angle with respect to the front direction. Moreover, since the second lens portion 130 has a curved surface shape that is convex toward the back side, such light L2 is diffused in its emission direction.

Further, the optical structure 100 directs the light L3 emitted from the liquid crystal panel 15 in a direction forming a large angle with respect to the front direction to the side surface 120S (the interface between the lens portion 110 and the low refractive index layer 103) or the second lens portion. The light is refracted at the interface between 130 and the lens portion 110 to control its traveling direction, and is totally reflected at the light output side interface of the optical structure 100 to return to the liquid crystal panel 15 side. In addition, due to the shape of the second lens portion 130, the light emitted from the liquid crystal panel 15 in a direction forming a large angle with respect to the front direction, such as the light L3, is diffused. The amount of light that is totally reflected and returns to the liquid crystal panel 15 increases.

In this way, the light L2 emitted from the liquid crystal panel 15 with high color reproducibility to the vicinity of the front direction is directed in a direction forming a large angle with respect to the front direction, and the light L2 is directed from the liquid crystal panel 15 with low color reproducibility to the front direction. By returning the light L3 emitted in a direction forming a large angle to the liquid crystal panel 15 side, the optical structure 100 of the present embodiment and the display device 10 including the same form a large angle with respect to the front direction of the display device 10. It is possible to improve color reproducibility and gradation expression when viewed from any direction.
Part of the light (light L4) emitted from the liquid crystal panel 15 in a direction forming a larger angle with respect to the front direction enters the lens portion 110 from the flat portion 122A, is totally reflected by the side surface 120S, The light is refracted and diffused at the interface between the lens portion 130 and the lens portion 110, and emitted in the front direction or its vicinity. Since such light L4 has a small amount of light and is further diffused, it does not deteriorate the color reproducibility of an image viewed in the front direction.
In addition, since the optical structure 100 of the present embodiment includes the intermediate layer 105, the refractive index difference between the low refractive index layer 103 and the intermediate layer 105 and the refractive index difference between the intermediate layer 105 and the base material 101 are reduced. , the reflection at the interface between each layer can be suppressed, and the luminance can be improved.

(Manufacturing method of optical structure 100)
Next, an example of a method for manufacturing the optical structure 100 of the embodiment will be described.
FIG. 6 is a diagram illustrating an example of a method for manufacturing the optical structure 100 of the embodiment.
First, as shown in FIG. 6(a), a mold 700 having an uneven shape 701 for shaping the uneven shape 120 on its surface is prepared, and as shown in FIG. An ultraviolet curable resin R1 that forms the lens portion 110 and the high refractive index layer 102 is applied to the surface on which the shape 701 is formed, and the substrate 101 is placed on the ultraviolet curable resin R1. At this time, the surface of the base material 101 is not coated with a primer or the like for improving adhesion to the ultraviolet curable resin R1. This UV curable resin R1 contains a component capable of dissolving the base material 101 made of TAC, as described above.

At this time, as shown in FIG. 6C, the surface of the base material 101 is dissolved by the component that dissolves the base material 101 contained in the ultraviolet curable resin, and the dissolved TAC is eluted to the ultraviolet curable resin R1 side. and permeate. As a result, a resin R2 in which the dissolved TAC permeates the UV curable resin R1 is formed in the portion corresponding to the layer main body 105A of the intermediate layer 105 and the region to be the second lens portion 130 .
Since the base material 101 has a lower refractive index than the ultraviolet curable resin R1, the refractive index of the resin R in which the TAC dissolved from the base material 101 permeates the ultraviolet curable resin R1, that is, the refractive index of the intermediate layer 105 is It is smaller than the lens portion 110 and the high refractive index layer 102 and larger than the substrate 101 .

Next, as shown in FIG. 6D, ultraviolet rays are applied to cure the ultraviolet-curable resin R1 and the resin R2. Thereby, the lens portion 110, the high refractive index layer 102, and the intermediate layer 105 are cured and formed. Thereby, the second lens portion 130 of the intermediate layer 105 is formed without alignment with the lens portion 110 or the like.
Next, as shown in FIGS. 6(e) and 6(f), the laminate of the base material 101, the intermediate layer 105, and the lens portion 110 is released from the mold, and a resin for forming the low refractive index layer 103 is applied. Then, the concave-convex shape 120 formed by the lens portion 110 and the intermediate layer 105 is filled and flattened. When the low refractive index layer 103 is an adhesive, the optical structure 100 is formed by the above-described flattening, and then may be attached to the liquid crystal panel 15, or a release sheet or the like may be laminated and transported. or can be stored.
When the resin forming the low refractive index layer 103 is not an adhesive, the applied resin forming the low refractive index layer 103 is cured to form the optical structure 100 .

Although the antireflection layer 104 is omitted in FIG. 6 and the above description, it may be formed on one side of the substrate 101 in advance. It may be formed on the base material 101 after the formation of the lens part 110 or after the formation of the low refractive index layer 103 .
Further, in FIG. 6, the mold 700 has been described with an example of a flat plate shape, but it is not limited to this, and may be, for example, a cylinder shape having uneven shapes for shaping on the peripheral side surface.

(Comparison between Examples and Comparative Examples)
Here, an optical structure 100 of an example of the present embodiment and an optical structure 500 of a comparative example were produced, and their cross-sectional shapes were confirmed.
Next, the display device 10 of the example provided with the optical structure 100 of this example, the display device of the comparative example 1 provided with the optical structure 500 of the comparative example, and the display device of the comparative example 2 not provided with the optical structure were produced. and examined for color change. In addition, regarding the optical structure 500 of the comparative example and the optical structure 100 of the example, the state of light incident on each optical structure was confirmed by simulation.

FIG. 7 is a cross-sectional photograph of the optical structure 100 of Example and the optical structure 500 of Comparative Example. FIG. 7(a) is a cross-sectional photograph of the optical structure 100 of the example, and FIG. 7(b) is a cross-sectional photograph of the optical structure 500 of the comparative example. Note that FIG. 7 shows cross-sectional photographs of the optical structures of Examples and Comparative Examples before the formation of the low refractive index layer 103 .
As shown in FIG. 7A, the optical structure 100 of the example has an intermediate layer 105 and a second lens portion 130 formed at a position corresponding to the lens portion 110 .

In the optical structure 500 of the comparative example, a primer is applied to one side of the substrate 101, and an ultraviolet curable resin layer 502 having a lens portion 510 is formed thereon by the same molding die as in the example. . This UV curable resin layer 502 has a higher refractive index than the low refractive index layer 103 and the substrate 101 . As shown in FIG. 7B, in the optical structure 500 of the comparative example, the lens portion 110 is formed integrally with the ultraviolet curable resin layer 502, but the intermediate layer 105 is not formed. Further, in the optical structure 500 of the comparative example, the uneven shape formed by the lens portions 110 of the ultraviolet curable resin layer 502 is similar to the uneven shape 120 formed by the intermediate layer 105 and the lens portions 110 of the optical structure 100 of the example. Shape.

FIG. 8 is a ray tracing diagram in the optical structure 100 of the example.
FIG. 9 is a ray tracing diagram in the optical structure 500 of the comparative example.
8 and 9 show states of light incident at an incident angle of 52 degrees in cross sections of the optical structure 100 of the example of the present embodiment and the optical structure 500 of the comparative example.
FIG. 10 is a graph showing color changes in the display device 10 of Example and the display devices of Comparative Examples 1 and 2. FIG.

In the optical structure of the example, the dimensions of each part are as follows.
Base material 101: made of TAC, thickness 60 μm, refractive index 1.49
Intermediate layer 105: A resin layer formed by applying a dimethylacrylamide-containing acrylate-based UV-curable resin to the base material 101, with a refractive index of 1.52.
Lens portion 110: Acrylate UV-curable resin containing dimethylacrylamide, refractive index 1.62, slope angle range α=19.5, average slope angle θ0=11.2, pitch P=33.0 μm, height H= 16.5 μm
High refractive index layer 102: Acrylate UV curable resin containing dimethylacrylamide, refractive index 1.62
Low refractive index layer 103: acrylic adhesive, refractive index 1.48

The optical structure 500 of the comparative example is the same as the optical structure 100 of the example except that the intermediate layer 105 is not provided and the lens part 110 is formed integrally with the ultraviolet curable resin layer 502. is the shape of
UV curable resin layer 502: acrylate UV curable resin, refractive index 1.62

In the optical structure 500 of the comparative example, the interface (unevenness shape 120) between the lens portion 110, the ultraviolet curable resin layer 502, and the low refractive index layer 103, as described in the description with reference to FIG. Part of the light (light with low color reproducibility) incident from a direction forming a large angle with respect to (the normal direction of the display surface 15A, the second direction d2) is totally reflected at the interface on the light exit side, and the liquid crystal panel In addition, it is possible to direct part of the light incident from the front direction and the direction forming a small angle with respect to the front direction to be emitted in a direction forming a large angle with respect to the front direction. However, since the optical structure 500 of the comparative example does not include the second lens portion 130, diffusion is small in any direction.

FIG. 9 shows the state of light incident on the optical structure 500 of the comparative example from an incident angle of 52 degrees, that is, from an oblique direction forming 52 degrees with respect to the front direction. Due to total reflection and refraction at the interface between 103 and lens portion 110, the light is emitted in the vicinity of the front or in an oblique direction forming an angle with respect to the front direction, but the light emitted in any direction is not diffused. small. In addition, in FIG. 9, there is no light that is totally reflected at the interface on the light exit side of the optical structure 500 of the comparative example and returned to the rear side.

On the other hand, in the optical structure 100 of the example, as described in the description with reference to FIG. , and part of light (light with low color reproducibility) incident from a direction forming a large angle with respect to the front direction is refracted by the interface between the lens portion 110 and the convex second lens portion 130. part of the light (light with high color reproducibility) that enters from the front direction and a direction that forms a small angle with respect to the front direction Diffuse and emit in a direction that forms a large angle with respect to the front direction.

FIG. 8 shows the state of light incident on the optical structure 100 of the example from an oblique direction that forms an angle of 52 degrees with respect to the front direction. By refraction or total reflection at the interface and further refraction at the interface between the second lens portion 130 and the lens portion 110, the near-front direction and the direction forming an angle with the front direction (in particular, a large angle with respect to the front direction). direction forming an angle) is emitted with a greater degree of diffusion.
Therefore, in the display device 10 of the embodiment, the viewing angle can be widened, the luminance within the viewing angle can be sufficiently maintained, and the color reproducibility and gradation expression can be improved.

In addition, as shown in FIG. 8, the optical structure 100 of the embodiment refracts and diffuses light incident from a direction forming a large angle with respect to the front direction at the interface between the second lens portion 130 and the lens portion 110. This makes it possible to increase the amount of light that is totally reflected by the light exit surface of the optical structure 100 and travels toward the liquid crystal panel 15 compared to the optical structure 500 of the comparative example. As a result, the optical structure 100 of the embodiment can further improve color reproducibility, gradation expression, and the like.

In the graph shown in FIG. 10, the horizontal axis indicates the viewing angle of the light emitted from the display devices of Example and Comparative Examples 1 and 2, and the vertical axis indicates the color change Δu'v'. . The graph shown in FIG. 10 shows the magnitude of color change within the viewing angle of light emitted from each display device.
When the angle shown on the horizontal axis is 0 degree, it means that the angle is viewed along the normal direction (the front direction of the display device). It means that it was viewed along a direction inclined by degrees.
Also, the color change Δu'v' shown on the vertical axis indicates the color difference, and is calculated from the colors defined by u' and v' in the uniform color space. A value of Δu'v' at an angle θ in a certain viewing angle is expressed by the following equation (1).

Color coordinates u' and v' in the uniform color space in equation (1) are expressed by the following equations (2-1) and (2-2), respectively.

In each of the above formulas, x and y are color coordinates defined in the CIE1931 color space (CIE xyY color space).
Further, in the evaluation of the color change shown in FIG. 10, a multi-domain VA type liquid crystal display device manufactured by Sony Corporation was used as the main body of the display device provided with the optical structure. As for the display device of Comparative Example 2, only the main body of this display device was used without mounting the optical structure.
First, the color change was measured when a blue image was displayed by the pattern generator without the optical structure in the body of the display device (that is, the display device of Comparative Example 2). Next, the optical structures of Examples and Comparative Examples were provided on the body of this display device, respectively, and the color change when the same image as described above was displayed was measured. "Spectroradiometer SR-2" manufactured by Topcon Corporation was used to measure these color changes.

Referring to FIG. 10 , the optical structure 100 is not provided in the display device of the example provided with the optical structure 100 of the example and the display device of the comparative example 1 provided with the optical structure 500 of the comparative example. It can be seen that the color change within the viewing angle is suppressed as compared with the display device of Comparative Example 2, which does not have any.
On the other hand, it can be seen that the display device 10 of the example suppresses color change compared to the display device of the comparative example 1, particularly within the viewing angle range of 40 to 60 degrees. This is due to the diffusion effect due to refraction of light at the interface of the second lens portion 130, as shown in FIGS.
Therefore, according to the present embodiment, it is possible to expand the viewing angle and improve the color reproducibility and color gradation expression within the viewing angle while maintaining good display quality in the front view of the display device. It is possible to provide the optical structure 100 and the display device 10 having the optical structure 100, which can effectively suppress deterioration in color reproducibility and gradation expression when observed from an oblique direction.

(deformed form)
Various modifications and changes are possible without being limited to the embodiments described above, and they are also within the scope of the present invention.
(1) In the embodiment, the optical structure 100 may have a configuration in which the concave-convex shape 120 is positioned closer to the light exit side than the substrate 101 .
FIG. 11 is a diagram showing an example of a modified form of the optical structure 100. FIG. FIG. 11 shows a modified form of the optical structure 100 and the liquid crystal panel 15 for easy understanding.
As shown in FIG. 11, the optical structure 100 may be arranged on the viewer side of the liquid crystal panel 15 with the substrate 101 on the back side (liquid crystal panel 15 side). At this time, a bonding layer (not shown) made of an adhesive layer or the like may be formed between the substrate 101 and the liquid crystal panel 15, and the bonding layer may be used for bonding.
Even with such a configuration, it is possible to display a good image with sufficient color reproducibility and gradation expression to an observer who observes the display device 10 from an oblique direction.

(2) In the embodiment, the refractive index of the lens portion may be smaller than that of the intermediate layer or the like.
FIG. 12 is a diagram showing an example of a modified form of the optical structure 100. FIG. FIG. 12 shows a modified form of the optical structure 100 and the liquid crystal panel 15 for easy understanding.
In the optical structure 100 of this modified form, as shown in FIG. 12, the intermediate layer 107 is formed on the back side of the base material 101 (the side opposite to the antireflection layer 104 side) and corresponds to the second lens portion 150. Then, the lens portions 160 are formed, the low refractive index layer 109 is formed between the adjacent lens portions 160, and the high refractive index layer 108 is laminated so as to fill the uneven shape of the lens portions 160 and the like.
The refractive index of each portion is in the order of the high refractive index layer 108, the intermediate layer 107, the base material 101, the lens portion 160 and the low refractive index layer 109 from the highest. The lens portion 160 and the low refractive index layer 109 are made of the same material and have the same refractive index. The refractive index of the intermediate layer 107 is lower than that of the base material 101 (manufactured by TAC) and higher than that of the lens portion 160 and the low refractive index layer 109 . Further, the refractive indices of the high refractive index layer 108, the lens portion 160, and the low refractive index layer 109 correspond to the refractive indices of the lens portion 110, the high refractive index layer 102, and the low refractive index layer 103 of the above-described embodiment, respectively. may be
Even with such a configuration, it is possible to display a good image with sufficient color reproducibility and gradation expression to an observer who observes the display device 10 from an oblique direction.

(3) The method for manufacturing the optical structure 100 is not limited to the method for manufacturing the optical structure 100 shown in the embodiment, and the method for manufacturing the optical structure 100 may be selected as appropriate.
For example, on one side of the base material 101, a resin having a refractive index lower than that of the lens portion 110 and higher than that of the low refractive index layer 103 and having optical transparency is applied to the intermediate layer 105 (layer main body 105A and second lens portion 130). ) is molded using a molding die or the like, and the lens portion 110 is formed from a resin having optical transparency and a refractive index higher than that of the intermediate layer 105, and the uneven shape of the lens portion 110 is filled. A method of forming the low refractive index layer 103 so as to be planarized may be employed.
If such a manufacturing method is adopted, it is necessary to align the lens portion 110 and the second lens portion 130 when forming the lens portion 110. Therefore, the manufacturing method shown in the above embodiment is preferable. The optical structure 100 can be manufactured more easily. However, even when manufactured by this manufacturing method, the same effects as those of the optical structure 100 and the display device 10 of the embodiment can be obtained.

(4) In the embodiment, an example in which the optical structure 100 includes the antireflection layer 104 on the viewer side of the substrate 101 is shown. A configuration including a dirt layer or the like may be used, or a configuration in which a plurality of these layers are laminated may be used.

(5) In the embodiment, the surface light source device 20 has a configuration in which the light source 24 is provided not only at the position facing the light incident surface 33 of the light guide plate 30 but also at the position facing the opposite surface 34 of the light guide plate 30; A surface light source device may be used. In this case, the unit prisms 70 of the optical sheet 60 and the uneven shape of the rear surface 32 of the light guide plate 30 may be symmetrical in the first direction d1.
Further, in the embodiment, the surface light source device 20 is not limited to the edge light type, and may be a direct type surface light source device.

(6) In the embodiment, the example in which the intermediate layer 105 is provided with the second lens portion 130 is supported, but this is not limitative. The surface of the intermediate layer 105 may be substantially planar, or the surface of the intermediate layer 105 on the back side may have a moderate uneven shape (undulation).
FIG. 13 is a diagram showing an example of a modified form of the optical structure 100. FIG. FIG. 13 shows an example in which the back side surface of the intermediate layer 105 is substantially flat.
FIG. 14 is a cross-sectional photograph of an example of a modified form of the optical structure 100. FIG. FIG. 14 shows an example in which the back side surface of the intermediate layer 105 (the interface between the intermediate layer 105 and the lens portion 110 and the high refractive index layer 102) has a gentle uneven shape (undulation). Also, FIG. 14 shows a cross-sectional photograph of an example of a modified form of the optical structure 100 before the low refractive index layer 103 is formed.

In the form in which the surface of the intermediate layer 105 on the back side is substantially planar, effects such as improvement in color reproducibility and improvement in gradation expression are small compared to the optical structure 100 of the example of the embodiment described above. However, in this embodiment, as compared with the optical structure 500 of the comparative example described above, the intermediate layer 105 improves the adhesion between the substrate 101 and the layer of the ultraviolet curable resin R1, and By forming the intermediate layer 105 between the lens portion 110 and the high refractive index layer 102, the difference in refractive index between each layer is reduced, and the light amount loss due to reflection at the interface is reduced, thereby increasing the light transmittance. can be improved.
In addition, in a mode in which the back side surface of the intermediate layer 105 has a gently uneven shape, in addition to the effect of improving the adhesion and the transmittance described above, the interface between the intermediate layer 105 and the lens portion 110 and the high refractive index layer 102 Although the diffusion effect is smaller than that of the second lens portion 130, the uneven shape of the second lens portion 130 can produce a diffusion effect. The uneven shape of the surface of the intermediate layer 105 on the back side may be irregular or regular.

Although the present embodiment and modifications can be used in combination as appropriate, detailed description thereof will be omitted. Moreover, the present invention is not limited to each embodiment described above.

REFERENCE SIGNS LIST 10 display device 15 liquid crystal panel 20 surface light source device 24 light source 28 reflective sheet 30 light guide plate 60 optical sheet (prism sheet)
REFERENCE SIGNS LIST 100 optical structure 101 substrate 105 intermediate layer 110 lens portion 103 low refractive index layer 104 antireflection layer 120 uneven shape 130 second lens portion

Claims (10)

An optical structure arranged on a viewer side of a display surface of a display device,
a substrate layer;
a first layer laminated on the base material layer;
A plurality of the first layers are arranged in one direction along the surface of the first layer opposite to the base layer side, extend in a direction intersecting the arrangement direction, and extend to the side opposite to the base layer side. a convex lens portion;
a second layer laminated so as to fill the uneven shape formed by the first layer and the lens portion;
with
The uneven shape has the lens portions as convex portions and the flat portions located between the adjacent lens portions as concave portions,
A plurality of the first layers are arranged along the surface opposite to the base layer side, along the direction in which the lens portions are arranged, and extend in a direction intersecting the direction in which the lens portions are arranged. Equipped with a second lens portion that is convex to the side opposite to the material layer side,
an interface between the second lens portion and the lens portion and an interface between the lens portion and the second layer have a difference in refractive index;
The slope angle range α, which is the difference between the maximum angle and the minimum angle formed by the uneven side surface with the normal direction of the base material layer, is 3 degrees or more and 60 degrees or less;
An optical structure characterized by: An optical structure arranged on a viewer side of a display surface of a display device,
a substrate layer;
a first layer laminated on the base material layer;
A plurality of the first layers are arranged in one direction along the surface of the first layer opposite to the base layer side, extend in a direction intersecting the arrangement direction, and extend to the side opposite to the base layer side. a convex lens portion;
a second layer laminated so as to fill the uneven shape formed by the first layer and the lens portion;
with
The uneven shape has the lens portions as convex portions and the flat portions located between the adjacent lens portions as concave portions,
A plurality of the first layers are arranged along the surface opposite to the base layer side, along the direction in which the lens portions are arranged, and extend in a direction intersecting the direction in which the lens portions are arranged. Equipped with a second lens portion that is convex to the side opposite to the material layer side,
an interface between the second lens portion and the lens portion and an interface between the lens portion and the second layer have a difference in refractive index;
The average slope angle θ0 of the uneven side surface defined by the straight line connecting the end points of the uneven side surface and the normal direction of the base layer is 9 degrees or more and 18 degrees or less. ,
An optical structure characterized by: In the optical structure according to claim 1 or claim 2,
In a cross section parallel to the thickness direction of the optical structure and the arrangement direction of the lens portions, the second lens portions are positioned within the lens portions;
An optical structure characterized by: In the optical structure according to any one of claims 1 to 3,
The refractive index of the lens portion is higher than the refractive indexes of the first layer and the second layer,
The refractive index of the first layer is lower than the refractive index of the lens portion and higher than the refractive indexes of the base layer and the second layer;
An optical structure characterized by: In the optical structure according to any one of claims 1 to 4,
the lens section has a trapezoidal cross-sectional shape in the thickness direction of the optical structure and in the arrangement direction of the lens section;
An optical structure characterized by: In the optical structure according to any one of claims 1 to 5,
The second lens part has a cross-sectional shape in the thickness direction of the optical structure and in the arrangement direction of the second lens part that is curved so as to be convex toward the second layer;
An optical structure characterized by: A display device comprising the optical structure according to any one of claims 1 to 6 on the viewer side of the display surface. The display device according to claim 7,
a liquid crystal panel having the display surface;
a surface light source device arranged on the back side of the liquid crystal panel and irradiating the liquid crystal panel with light;
to provide
A display device characterized by: The display device according to claim 8,
In the liquid crystal panel, when the voltage applied to the liquid crystal molecules is off or at a minimum value, the liquid crystal molecules are oriented along the normal direction of the display surface, and light from the surface light source device is blocked. A VA system configured to gradually increase the transmittance of light from the surface light source device by gradually increasing the voltage applied to the liquid crystal molecules to gradually incline the liquid crystal molecules along the display surface. be a liquid crystal panel,
A display device characterized by: In the display device according to any one of claims 7 to 9,
wherein the optical structure is arranged such that the second layer faces the display surface;
A display device characterized by:

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