Optical sheet, light control member, surface light source device, image source unit, and display device

Abstract

To provide an optical sheet that makes it possible to efficiently control a light exiting angle as desired.SOLUTION: A planer optical sheet is formed by laminating a plurality of layers, and includes an optical function layer and an optical element layer. The optical function layer includes: light transmissive portions having the trapezoidal cross sections, extending in one direction and arranged at intervals in a direction different from the one direction; and a light absorbing portion that is arranged between the adjacent light transmissive portions. The optical element layer extends so as to be offset from the one direction at an angle of 1° to 45° inclusive in a front view of the optical sheet, the optical element layer having a plurality of unit optical elements that are ridges aligned in a direction different from a direction in which the optical element layer extends. The unit optical element includes a triangular cross section having a main refraction surface and a rise surface. The main refraction surface is inclined at an angle greater than 45° and equal to or less than 89° with respect to the normal direction of a light exiting surface of the optical function layer. A pitch between the light transmissive portion and the light absorbing portion is 20 μm to 100 μm inclusive, and the thickness of the light absorbing portion is 50 μm to 150 μm inclusive.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an optical sheet that controls the outgoing direction of incident light, and to a light control member, a surface light source device, an image source unit, and a display device that include the optical sheet. [Background technology]

[0002] 2. Description of the Related Art Display devices such as car navigation systems, televisions, and computer monitors are equipped with an image source that emits an image to be displayed, as well as an optical sheet that improves the quality of the image light and provides it to the viewer.

[0003] The direction of the image light is often set to the front or at an angle up, down, left, or right from the front, so that the image displayed on the screen can be viewed from any desired position. The direction of the light can also be restricted as needed to prevent peeping, etc. Optical sheets for controlling the light output angle in this way are disclosed in, for example, Patent Documents 1 to 3. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-171701 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-059565 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-113054 Summary of the Invention [Problem to be solved by the invention]

[0005] The diversification of devices in recent years has made it necessary to control the emission direction of image light differently or more precisely. For example, in car navigation systems, since people sit in roughly fixed positions inside a car, a wide viewing angle is not necessarily required; it is sufficient to emit images toward the location of people, particularly the driver. Therefore, the image light is emitted diagonally upward rather than straight ahead, making it easier for the driver to see. However, if the image is emitted too far upward, it can cause problems with the image being reflected on the windshield. Such an emission angle differs depending on the vehicle model, and therefore more precise control of the emission angle is required. For example, the above-mentioned patent document has the following problems:

[0006] For example, when the viewing angle is controlled using an optical sheet as described in Patent Document 1, it is difficult to perform fine control of the viewing angle. Even if the viewing angle is controlled, there is a problem that the utilization efficiency of the image light decreases.

[0007] For example, the optical sheet described in Patent Document 2 has high performance in emitting image light in a desired direction, but restricts the emission of image light in other directions. As a result, especially in a display device with a large screen, the center of the screen is bright, but the brightness of the peripheral areas of the screen is relatively dark compared to the center. This tendency is particularly noticeable when the screen is viewed from an angle relative to the front.

[0008] For example, in the technology described in Patent Document 3, it is necessary to significantly change the shapes of the light-transmitting and light-absorbing parts between the center and the periphery of the sheet, which does not necessarily allow for precise control of light. In addition, this increases the difficulty of manufacturing, making it difficult to create a precise shape.

[0009] Therefore, an object of the present invention is to provide an optical sheet that can efficiently control the desired light output angle, and also to provide a light control member, a surface light source device, an image source unit, and a display device that include this optical sheet. [Means for solving the problem]

[0010] The present invention will be described below.

[0011] One aspect of the present invention is a planar optical sheet formed by stacking a plurality of layers, the optical sheet comprising: an optical function layer that is one of the plurality of layers; and an optical element layer that is another of the plurality of layers; the optical function layer has a trapezoidal cross section and extends in one direction, and comprises light-transmitting portions that have a trapezoidal cross section and extend in one direction, and are arranged at intervals in a direction different from the one direction; and light-absorbing portions that are arranged between adjacent light-transmitting portions; the optical element layer comprises unit optical elements that are protrusions that extend at an angle of 1° to 45° with respect to the one direction in a front view of the optical sheet, and are arranged in a direction different from the extending direction; the unit optical elements have a triangular cross section having a main refraction surface and a rise surface, and the main refraction surface is a surface that is inclined at an angle of more than 45° and not more than 89° with respect to the normal direction of the light-emitting surface of the optical function layer; the pitch between the light-transmitting portions and the light-absorbing portions is 20 μm to 100 μm, and the thickness of the light-absorbing portions is 50 μm to 150 μm. Here, "front view of the optical sheet" refers to the viewpoint when the optical sheet is viewed from the light-emitting surface, and "0° to 45° in front view of the optical sheet" means that when the optical sheet is viewed from the front, the unit optical elements extend at an angle of 0° to 45° with respect to the direction in which the light-transmitting portions extend (one direction).

[0012] Another aspect of the present invention is a planar optical sheet formed by stacking a plurality of layers, the optical sheet comprising: an optical functional layer that is one of the plurality of layers; and an optical element layer that is another of the plurality of layers; the optical functional layer has a trapezoidal cross section and extends in one direction, and comprises light-transmitting portions that have a trapezoidal cross section and extend in one direction, and are arranged at intervals in a direction different from the one direction; and light-absorbing portions that are arranged between adjacent light-transmitting portions; the optical element layer comprises unit optical elements that are protrusions that extend at an angle of 1° to 45° with respect to the one direction in a front view of the optical sheet, and are arranged in a direction different from the extending direction; the unit optical elements have a triangular cross section with a main refraction surface and a rise surface, and the main refraction surface is inclined at an angle of more than 0° and less than 17° with respect to the layer surface of the optical functional layer; the pitch between the light-transmitting portions and the light-absorbing portions is 20 μm to 100 μm, and the thickness of the light-absorbing portions is 50 μm to 150 μm.

[0013] The surface of the unit optical element may be roughened.

[0014] The main refractive surface and the rise surface may be roughened.

[0015] The arrangement pitch of the light transmitting parts is P a (μm), and the arrangement pitch of the unit optical elements is P o (μm), a and b are integers between 1 and 10, P m =|(a·P a ·b·P o ) / (a·P a -b·P o )| As, there is P a , P o P obtained from all combinations of a and b for m The largest of these is P mx (μm), P mx may be configured so that the thickness is 10000 (μm) or less.

[0016] The protruding height of the unit optical elements may be 1 μm or more and 10 μm or less.

[0017] A gap may be provided between adjacent unit optical elements.

[0018] It is possible to provide a light control member in which two or more of the above optical sheets are arranged so that the extension direction of the light-transmitting portion of one optical sheet intersects with the extension direction of the light-transmitting portion of the other optical sheet when viewed from the front of the optical sheets.

[0019] It is possible to provide a surface light source device including a light source and the optical sheet arranged closer to the viewer than the light source.

[0020] It is possible to provide a surface light source device including a light source and the light control member arranged closer to the viewer than the light source.

[0021] It is possible to provide an image source unit including the above surface light source device and a liquid crystal panel arranged on the light output side of the surface light source device.

[0022] In the image source unit, the light-transmitting portion, the light-absorbing portion, and the unit optical elements may extend in a horizontal direction and be arranged in a vertical direction.

[0023] A display device can be provided in which the image source unit is housed in a housing. [Effects of the Invention]

[0024] According to the present invention, the light output angle can be controlled efficiently. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 2 is an exploded perspective view illustrating the image source unit 10. [Figure 2] FIG. 2 is an exploded view showing a cross section of the image source unit 10. [Figure 3] 10 is an exploded view showing another cross section of the image source unit 10. FIG. [Figure 4] FIG. 2 is an enlarged cross-sectional view focusing on the optical sheet 30. [Figure 5] FIG. 2 is a further enlarged cross-sectional view of the optical sheet 30. [Figure 6] 10A and 10B are diagrams illustrating modified examples of the optical sheet 30. [Figure 7] 3A to 3C are diagrams illustrating examples of optical paths of light passing through the optical sheet 30. [Figure 8] 10 is a diagram illustrating control of the light output angle when a light output side light control layer 35 is provided. FIG. [Figure 9] 10 is a diagram illustrating an embodiment in which an output-side light control layer 135 is provided. FIG. [Figure 10] 10A and 10B are diagrams illustrating an example of an optical path through the light-emitting-side light control layer 135. FIG. [Figure 11] 10 is a diagram illustrating a change in the light output angle when a light output side light control layer 135 is provided. FIG. [Figure 12] FIG. 2 is an exploded perspective view illustrating the image source unit 210. [Figure 13] FIG. 2 is an exploded view showing a cross section of the image source unit 210. [Figure 14] FIG. 2 is an exploded view showing another cross section of the image source unit 210. [Figure 15] FIG. 2 is an enlarged cross-sectional view focusing on the second optical sheet 230. [Figure 16] 10 is a further enlarged cross-sectional view of a portion of the second optical sheet 230. FIG. [Figure 17] 3A to 3C are diagrams illustrating examples of optical paths in the first optical sheet 30. FIG. [Figure 18] 10A and 10B are diagrams illustrating light control in the second optical sheet 230. FIG. [Figure 19] FIG. 2 is an exploded perspective view illustrating the image source unit 310. [Figure 20] FIG. 3 is an exploded view showing a cross section of the image source unit 310. [Figure 21] FIG. 10 is an exploded view showing another cross section of the image source unit 310. [Figure 22] 10 is an enlarged view focusing on the optical sheet 330. FIG. [Figure 23] FIG. 10 is a further enlarged view of the optical sheet 330. [Figure 24] 10 is a diagram illustrating the path of light passing through an optical sheet 330. FIG. [Figure 25] 10 is a diagram illustrating the light output characteristics of an optical sheet 330. FIG. [Figure 26] 10 is a diagram showing characteristics of a light source in Test Example A. FIG. [Figure 27] FIG. 10 is a graph showing the results of Test Example A1. [Figure 28] FIG. 10 is a graph showing the results of Test Example A2. [Figure 29] FIG. 10 is a graph showing the results of Test Example A3. [Figure 30] 10 is a diagram showing characteristics of a light source in Test Example B. FIG. [Figure 31] 31(a) and 31(b) are diagrams showing the results of Test Example B1. [Figure 32] 25(a) and 25(b) are diagrams showing the results of Test Example B2. [Figure 33] 10A and 10B are diagrams illustrating a scene in which a rough surface is formed on the surface of a unit optical element. [Figure 34] 10A and 10B are diagrams illustrating the configuration of the optical sheet of Test Example E4. [Figure 35] 35(a), 35(b), and 35(c) are graphs showing the results of Test Example E. DETAILED DESCRIPTION OF THE INVENTION

[0026] The present invention will be described below based on the embodiments shown in the drawings. However, the present invention is not limited to these embodiments. In the drawings, shapes may be enlarged, deformed, or exaggerated for clarity, and some repeated reference numerals may be omitted.

[0027] Fig. 1 is a diagram illustrating the first embodiment and is an exploded perspective view of an image source unit 10 including an optical sheet 30. Fig. 2 shows a portion of an exploded cross-sectional view of the image source unit 10 taken along the line II-II (a line extending in the vertical direction) in Fig. 1, and Fig. 3 shows a portion of an exploded cross-sectional view of the image source unit 10 taken along the line III-III (a line extending in the horizontal direction). Note that the vertical direction and horizontal direction referred to here refer to the orientation in which the optical sheet 30 is disposed in a display device and the display device is used. Although detailed description will be omitted, such an image source unit 10 is housed in a housing (not shown) together with the usual equipment required for operation as the image source unit 10, such as a power supply for operating the image source unit 10 and electronic circuits for controlling the image source unit 10, to form a display device. In this embodiment, a liquid crystal image source unit will be described as one form of the image source unit, and a liquid crystal display device will be described as one form of the display device. The image source unit 10 will be described below.

[0028] The image source unit 10 includes a liquid crystal panel 15, a surface light source device 20, and a functional film 40. In this embodiment, the optical sheet 30 is included in the surface light source device 20. FIGS. 1 to 3 also show the orientation of the display device when it is installed.

[0029] The liquid crystal panel 15 has an upper polarizing plate 13 arranged on the viewer side, a lower polarizing plate 14 arranged on the surface light source device 20 side, and a liquid crystal layer 12 arranged between the upper polarizing plate 13 and the lower polarizing plate 14. The upper polarizing plate 13 and the lower polarizing plate 14 have the function of decomposing incident light into two orthogonal polarization components (P wave and S wave), transmitting the polarization component in one direction (parallel to the transmission axis) (for example, P wave) and absorbing the polarization component in the other direction (parallel to the absorption axis) orthogonal to the one direction (for example, S wave).

[0030] The liquid crystal layer 12 has a plurality of pixels arranged two-dimensionally, vertically and horizontally, along the plane of the layer, and an electric field can be applied to each pixel. The orientation of the pixel changes when an electric field is applied. As a result, the polarization direction of a polarized component (e.g., P wave) parallel to the transmission axis that has passed through the lower polarizer 14, located on the surface light source device 20 side (i.e., the light incident side), is rotated by 90° when passing through a pixel to which an electric field is applied, while maintaining its polarization direction when passing through a pixel to which no electric field is applied. Therefore, depending on whether or not an electric field is applied to the pixel, it is possible to control whether the polarized component (e.g., P wave) that has passed through the lower polarizer 14 is further transmitted through the upper polarizer 13, located on the light output side, or whether it is absorbed and blocked by the upper polarizer 13.

[0031] In this way, the liquid crystal panel 15 has a structure that controls the transmission or blocking of light from the surface light source device 20 for each pixel to display an image.

[0032] There are several types of liquid crystal panels, but in this embodiment, the type is not particularly limited and any known type of liquid crystal panel can be used, such as TN, STN, VA, MVA, IPS, and OCB.

[0033] Next, the surface light source device 20 will be described. The surface light source device 20 is an illumination device that is disposed on the opposite side of the liquid crystal panel 15 from the viewer side, and that emits planar light toward the liquid crystal panel 15. As can be seen from FIGS. 1 to 3, the surface light source device 20 of this embodiment is configured as an edge-light type surface light source device, and includes a light guide plate 21, a light source 25, a light diffusion plate 26, a prism layer 27, a reflective polarizing plate 28, an optical sheet 30, and a reflective sheet 39.

[0034] 1 to 3, the light guide plate 21 has a base 22 and rear surface optical elements 23. The light guide plate 21 is a plate-shaped member formed from a light-transmitting material. In this embodiment, one plate surface of the light guide plate 21 facing the viewer is a smooth surface, and the other plate surface opposite to this is a rear surface, on which a plurality of rear surface optical elements 23 are arranged.

[0035] Various materials can be used for the base 22 and rear optical element 23. However, it is possible to use materials that are widely used as materials for optical sheets incorporated into display devices, have excellent mechanical properties, optical properties, stability, processability, etc., and are inexpensively available. Examples of such materials include thermoplastic resins such as polymer resins with an alicyclic structure, methacrylic resins, polycarbonate resins, polystyrene resins, acrylonitrile-styrene copolymers, methyl methacrylate-styrene copolymers, ABS resins, and polyethersulfones, as well as epoxy acrylate and urethane acrylate reactive resins (e.g., ionizing radiation curable resins).

[0036] The base 22 is a plate-like portion having an appropriate thickness through which light is guided and which serves as a base for the rear optical element 23 .

[0037] The rear surface optical elements 23 are protruding elements formed on the rear surface side of the base 22, and in this embodiment, have a triangular prism shape. In this embodiment, the rear surface optical elements 23 are shaped like a pillar with a ridgeline of the protruding top extending horizontally, and a plurality of rear surface optical elements 23 are arranged in a direction perpendicular to the extending direction (vertical direction). The rear surface optical elements 23 in this embodiment have a triangular cross section, but this is not limited thereto, and the cross section may have any shape, such as a polygonal, hemispherical, partial sphere, or lens shape. The arrangement direction of the plurality of rear surface optical elements 23 is preferably the light guide direction. That is, the rear surface optical elements 23 are arranged in a direction away from the light source 25, and the ridge line of each rear surface optical element 23 extends parallel to the direction in which the light source 25 is arranged, or, if there is one long light source, the direction in which the light source extends.

[0038] In this specification, the term "triangular shape" does not only refer to a triangular shape in the strict sense, but also includes an approximately triangular shape that takes into account limitations in manufacturing technology, molding errors, etc. Similarly, terms used in this specification that specify other shapes or geometric conditions, such as "parallel," "orthogonal," "ellipse," and "circle," are also interpreted without being bound by their strict meanings, but rather include errors to the extent that similar optical functions can be expected.

[0039] The light guide plate 21 having such a configuration can be manufactured by extrusion molding or by molding the rear optical elements 23 on the base 22. In the light guide plate 21 manufactured by extrusion molding, the base 22 and the rear optical elements 23 can be integrally formed. When the light guide plate 21 is manufactured by molding, the rear optical elements 23 may be made of the same resin material as the base 22 or a different material.

[0040] 1 to 3, the light source 25 will be described. The light source 25 is disposed on one of the side surfaces (end surfaces) of the base 22 of the light guide plate 21 in the direction in which the rear optical elements 23 are arranged. The type of light source is not particularly limited, and can be configured in various forms such as a linear fluorescent lamp such as a cold cathode fluorescent tube, point-shaped LEDs (light-emitting diodes), or an incandescent lamp. In this embodiment, the light source 25 is made up of a plurality of LEDs, and is configured so that the turning on and off of each LED and / or the brightness of each LED when lit can be individually and independently adjusted by a control device (not shown). In this embodiment, the light source 25 is disposed on one side surface (end surface) as described above, but a light source may also be disposed on the side surface (end surface) opposite to this side surface (end surface). In this case, the shape of the rear optical element is formed following a known example so as to be suitable for the arrangement of the light source.

[0041] Next, the light diffusion plate 26 will be described. The light diffusion plate 26 is a layer that is disposed on the light output side of the light guide plate 21 and has the function of diffusing and outputting light that has entered there. This further improves the uniformity of the light output from the light guide plate 21 and makes scratches on the light guide plate 21 less noticeable. As a specific embodiment of the light diffusion plate, a known light diffusion plate can be used, and for example, a form in which a light diffusing agent is dispersed in a base material can be mentioned. As in this embodiment, the light diffusion plate 26 can also be used as a support plate for the prism layer 27. Furthermore, if the light output surface of the light guide plate 21 is smooth, the light diffusion plate 26 may be bonded to the light guide plate 21 to form an integrated body.

[0042] As can be seen from FIGS. 1 to 3 , the prism layer 27 is provided closer to the liquid crystal panel 15 than the light diffusion plate 26, and is a layer including unit prisms 27a that are convex toward the liquid crystal panel 15. In this embodiment, the unit prisms 27a have a triangular cross section and extend in a direction perpendicular to the light guide direction of the light guide plate 21 (the horizontal direction in this embodiment). A plurality of unit prisms 27a are arranged in the light guide direction of the light guide plate 21 (the vertical direction in this embodiment). This allows the optical function layer 32 to concentrate light in a direction that controls the light (the vertical direction in this embodiment), and allows the optical function layer 32 to efficiently totally reflect the light, thereby improving the light utilization efficiency. However, the cross-sectional shape of the unit prisms of such a prism layer can be any known shape (triangle, square, or other polygon) depending on the required function. Depending on the shape, it can focus light as described above, or conversely, it can further diffuse light. Furthermore, the extension direction and arrangement direction of the unit prisms are not limited to the above-described configuration and may be other configurations. For example, the unit prisms may extend in the light guide direction of the light guide plate, and multiple unit prisms may be arranged in a direction perpendicular to the light guide direction of the light guide plate.

[0043] The reflective polarizing plate 28 has the function of separating incident light into two orthogonal polarized components (P wave and S wave), transmitting the polarized component in one direction (parallel to the transmission axis) (for example, P wave) and reflecting the polarized component in the other direction orthogonal to the first direction (parallel to the reflection axis) (for example, S wave). A known structure can be used for such a reflective polarizing plate.

[0044] Next, the optical sheet 30 will be described. Fig. 4 shows an enlarged view of a portion of the optical sheet 30 taken from the perspective of Fig. 2. As can be seen from Figs. 1 to 4, the optical sheet 30 includes a base layer 31 formed in a sheet shape, an optical function layer 32 provided on one surface of the base layer 31 (the surface on the light guide plate 21 side in this embodiment), and an output-side light control layer 35 as a light control layer disposed on the other surface of the base layer 31 (the surface on the liquid crystal panel 15 side in this embodiment).

[0045] The base layer 31 is a flat sheet-like member that supports the optical function layer 32 and the light-emitting side light control layer 35 . Various materials can be used for the base layer 31. However, materials that are widely used as materials for optical sheets incorporated into display devices, have excellent mechanical properties, optical properties, stability, processability, and are inexpensively available, and can be used. Examples of such materials include polyethylene terephthalate resin (PET), triacetyl cellulose resin (TAC), methacrylic resin, and polycarbonate resin. Among these, TAC, methacrylic resin, and polycarbonate resin, which have low birefringence (retardation), are preferred in consideration of the combination of the surface light source device 20 and the lower polarizer 14. Furthermore, for applications requiring high heat resistance, such as in-vehicle applications, polycarbonate resin, which has a high glass transition point, is desirable. Specifically, the glass transition point of polycarbonate resin is 143°C, making it suitable for in-vehicle applications that generally require durability at 105°C.

[0046] The optical function layer 32 is a layer laminated on one surface of the base layer 31 (in this embodiment, the surface on the light guide plate 21 side), and is configured to have light-transmitting portions 33 and light-absorbing portions 34. The optical function layer 32 has a cross section shown in Fig. 4 and a shape extending toward the back / front of the page (in this embodiment, the horizontal direction when the image source unit 10 is viewed from the front), and the light-transmitting portions 33 and light-absorbing portions 34 are alternately arranged along the layer surface in a direction different from the extending direction (in this embodiment, the vertical direction).

[0047] The light-transmitting portion 33 is a portion whose main function is to transmit light, and in this embodiment, in the cross section shown in Figures 2 and 4, it is an element having an approximately trapezoidal cross-sectional shape with a long lower base on the base layer 31 side and a short upper base on the opposite side (the light guide plate 21 side). The light transmitting portions 33 extend in one direction (the horizontal direction in this embodiment) while maintaining their cross sections along the layer surface of the base layer 31, and are arranged at intervals in a direction different from the extending direction (the vertical direction in this embodiment). A gap (groove) having a substantially trapezoidal cross section is formed between adjacent light transmitting portions 33. Therefore, the gap (groove) has a trapezoidal cross section with a long bottom base on the top side (the light guide plate 21 side) of the light transmitting portion 33 and a short top base on the bottom side (the base layer 31 side) of the light transmitting portion 33, and the light absorbing portions 34 are formed by filling this gap with a necessary material, which will be described later. In this embodiment, a plurality of light transmitting portions 33 are connected on their lower bottom side (base layer side 31) by a sheet-like base portion 32a.

[0048] The light transmitting portion 33 has a refractive index of N t Such a light transmitting portion 33 can be formed by curing a light transmitting portion-constituting composition. Refractive index N t Although the value of is not particularly limited, the refractive index is preferably 1.47 or more from the viewpoint of appropriately reflecting light (including total reflection) at the interface with the light absorbing portion 34 on the slope of the trapezoidal cross section, as will be described later. However, since materials with too high a refractive index are often prone to cracking, the refractive index is preferably 1.61 or less. A refractive index of 1.49 or more and 1.56 or less is more preferable, and 1.56 is even more preferable.

[0049] The light absorbing portion 34 functions as a gap formed in the gap (groove) formed between adjacent light transmitting portions 33, and has a cross-sectional shape similar to the cross-sectional shape of the gap (groove). Therefore, the short upper base faces the liquid crystal panel 15 side (substrate layer 31 side), and the long lower base faces the opposite side (light guide plate 21 side in this embodiment). The light absorbing portion 34 has a refractive index of N r Specifically, the refractive index is N rLight-absorbing particles are dispersed in a transparent resin with a refractive index N r is the refractive index N of the light transmitting portion 33 t In this way, by making the refractive index of the light absorbing portion 34 smaller than the refractive index of the light transmitting portion 33, the condition is satisfied and light incident on the light transmitting portion 33 can be appropriately totally reflected at the interface with the light absorbing portion 34. Even when the total reflection condition is not satisfied, some light is reflected at the interface. Refractive index N r The value of is not particularly limited, and is preferably 1.47 or more, provided that the total reflection can be performed appropriately. However, since materials with too high a refractive index are often prone to cracking, the refractive index is preferably 1.61 or less. A refractive index of 1.49 or more and 1.56 or less is more preferable, and 1.49 is even more preferable.

[0050] Refractive index N of the light transmitting portion 33 t and the refractive index N of the light absorbing portion 34 r The difference in refractive index between the film and the glass substrate is not particularly limited, but is preferably greater than 0 and equal to or less than 0.14, and more preferably 0.05 or greater and 0.14 or less. By increasing the difference in refractive index, more light can be totally reflected.

[0051] The optical function layer 32 is not particularly limited, but may have, for example, the following shape: Fig. 5 shows a further enlarged view of a part of Fig. 4 .

[0052] θ shown in Fig. 5 11 is the angle between an interface 34a, which is the upper side of the light absorbing portion 34 when the optical sheet 30 is in the position shown in FIG. 1, and the normal to the layer surface of the optical function layer 32. 12 is the angle between the interface 34b, which is the lower side of the light absorbing portion 34, of the interfaces between the light transmitting portion 33 and the light absorbing portion 34 in the same posture, and the normal to the layer surface of the optical function layer 32. θ 11 is preferably 0° or more and 10° or less. 11is greater than 0° means that the angle is inclined downward from the light guide plate 21 side (light incident side) toward the liquid crystal panel 15 side (light exit side, base layer 31 side). θ 12 is preferably 0° or more and 10° or less. 12 is greater than 0° means that the angle is inclined upward from the light guide plate 21 side (light incident side) toward the liquid crystal panel 15 side (light exit side, base layer 31 side).

[0053] θ 11 , and θ 12 The relationship between the magnitudes of the angles can be set as needed.

[0054] Also, in Figure 4, P a The pitch of the light transmitting portion 33 and the light absorbing portion 34, represented by D, is preferably 20 μm or more and 100 μm or less, and more preferably 30 μm or more and 100 μm or less. a The thickness of the light absorbing portion 34 is preferably 50 μm or more and 150 μm or less, and more preferably 60 μm or more and 150 μm or less. By setting the thickness within these ranges, a more appropriate balance between light transmission and light absorption can be achieved.

[0055] In the present embodiment, an example has been shown in which the interface between the light transmitting portion 33 and the light absorbing portion 34 is linear in cross section, but the present invention is not limited to this and may be polygonal, convex curved, concave curved, etc. Furthermore, the cross-sectional shapes of the plurality of light transmitting portions 33 and light absorbing portions 34 may be the same or may be different with regularity.

[0056] In the above, an example has been described in which the extending direction of the light-transmitting portions 33 and the light-absorbing portions 34 is horizontal, but from the viewpoint of suppressing the occurrence of moire, it is preferable that the extending direction of the light-transmitting portions 33 and the light-absorbing portions 34 form an angle (bias angle α1) with respect to the arrangement direction of the pixels of the liquid crystal layer 12 when viewed from the front of the image source unit. The specific angle of this bias angle α1 is not particularly limited as long as it can prevent the occurrence of moire, but it is preferable that it be between 1° and 10°.

[0057] Next, a description will be given of the light-emitting side light control layer 35. The light-emitting side light control layer 35 functions as a light control layer, and when combined with the optical function layer 32, the two layers control the direction of light in combination. In this embodiment, the light-emitting-side light control layer 35 controls the direction of light emitted from the optical function layer 32 and emits the light. That is, in this embodiment, the light-emitting-side light control layer 35 further controls the direction of light controlled by the optical function layer 32 so that the emitted light has a desired emission angle.

[0058] Therefore, the light-emitting side light control layer 35 is configured to include a support layer 35a and an optical element layer 35b. The support layer 35a is a transparent sheet-like member that functions as a support for the optical element layer 35b. The support layer 35a can be made of the same material as the base layer 31 and the light transmitting portion 33 described above.

[0059] The optical element layer 35b is a layer that changes the direction of light emitted from the optical function layer 32, and is formed by arranging a plurality of unit optical elements 35c on the surface of the support layer 35a opposite to the optical function layer 32 side. The unit optical element 35c further controls the direction of the light controlled by the optical function layer 32. In this embodiment, the unit optical element 35c controls the direction of the light so as to efficiently shift the viewing angle vertically upward in the orientation shown in Figures 1 to 3. Figures 4 and 5 show the cross-sectional shape of the unit optical element 35c.

[0060] In this embodiment, the unit optical element 35c specifically has the following structure. Each unit optical element 35c is a triangular prism having a triangular cross section that protrudes to the side opposite the optical function layer 32 across the base layer 31, and is configured as a protrusion having the cross section and whose ridgeline extends in the same direction as the light-transmitting portions 33 and the light-absorbing portions 34 (bias angle α2=0°) or at an angle when viewed from the front of the optical sheet (bias angle α2≠0°). A plurality of unit optical elements 35c are arranged in a direction different from the extension direction.

[0061] When the ridgelines of the unit optical elements 35c are configured to extend at an angle relative to the direction in which the light-transmitting portions 33 and the light-absorbing portions 34 extend in a front view of the optical sheet (bias angle α2 ≠ 0°), it is preferable that the direction in which the light-transmitting portions 33 of the optical function layer 32 extend and the direction in which the ridgelines of the unit optical elements 35c extend are relatively inclined at a bias angle α2 greater than 0° and less than or equal to 45° in a front view of the optical sheet 30. This prevents moiré patterns from occurring due to the arrangement of the light-transmitting portions 33 and the light-absorbing portions 34 and the arrangement of the unit optical elements 35c. Furthermore, if the angle α2 is greater than 45°, the efficiency of light direction control by the unit optical elements 35c decreases. A more preferable angle α2 is between 1° and 10°.

[0062] 5, each unit optical element 35c has a main refraction surface 35d and a rise surface 35e. The main refraction surface 35d and the rise surface 35e form two surfaces of a triangular prism, and the other surface overlaps the support layer 35a and is fixed to the support layer 35a.

[0063] In this embodiment, the main refraction surface 35d is a refraction surface that, in the orientation shown in FIGS. 1 to 5, changes the direction of light emitted from the optical function layer 32 so that it is directed further upward. This allows the range of emitted light to be efficiently shifted vertically upward. In this case, the main refraction surface 35d is inclined so as to approach the optical function layer 32 as it goes downward (here, this direction is assumed to be inclined in the positive (+) direction). Therefore, in one unit optical element 35c, the main refraction surface 35d is on the bottom and the rise surface 35e is on the top. The inclination of the main refraction surface 35d is θ shown in FIG. 5 with respect to the normal direction of the optical function layer 32. 21 The angle is

[0064] θ 21 Specifically, the angle θ is preferably greater than 45° and less than 90° (the absolute value of the tilt angle of the main refractive surface is greater than 45° and less than 90°). This allows for reliable control of light to improve brightness in a desired direction (control of the light output angle). 21If θ is 45° or less, total reflection is likely to occur at the main refractive surface 35d, and there is a risk that a large amount of light will not be emitted. 21 If the angle is 90° or more, the surface will hardly function as a main refractive surface. More preferred θ 21 is between 80° and 89°. 21 By setting the width of the rise surface 35e within this range, the rise surface 35e can be kept small, and the generation of stray light due to the rise surface 35e can be reduced.

[0065] The rise surface 35e is a surface required to form the main refractive surface 35d. Fig. 5 shows θ 22 The inclination angle of the rise surface 35e, represented by θ, is preferably 80° or more and 100° or less with respect to the direction along the layer surface of the optical function layer 32. From the viewpoint of manufacturing, it is more preferably 80° or more and 90° or less. 22 If the angle is less than 80° or more than 100°, there is a risk that stray light from the rise surfaces 35e will increase.

[0066] The apex angle of the unit optical element 35c is the above θ 21 and θ 22 The angle is naturally determined from the angle of the angle, but it is preferably 45° or more and less than 90°.

[0067] Figure 4 shows P o The pitch of the unit optical elements 35c shown in is preferably small, from the viewpoint that even if moire occurs, it is difficult to see by reducing the moire pitch. Specifically, the pitch P o It is preferable that the thickness is 50 μm or less. In addition, since the optical function layer 32 is more difficult to manufacture than the optical element layer 35b, the pitch P a (See FIG. 4) and the pitch P of the unit optical elements 35c o It is desirable that P is smaller. o HA P a It is most desirable that the o , P a / 2, P a / 3, P aWhen the pitch is set to a constant value, such as 1 / 4, the ends of the light transmitting portions 33 and the ends of the unit optical elements 35c should not coincide with each other as much as possible. o and P a It is preferable that the least common multiple is large. On the other hand, when the unit optical element 35c becomes small, the accuracy decreases. o is preferably 10 μm or more.

[0068] More preferably, the arrangement pitch of the light transmitting portions 33 is P a (μm), the arrangement pitch of the unit optical elements 35c is P o (μm), P mx (μm) is 10000 (μm) or less. This makes it possible to more reliably prevent the occurrence of moire. mx can be obtained as follows: P mx HA P m can be obtained based on P m is expressed by the following equation: P m =|(a·P a ·b·P o ) / (a·P a -b·P o )|

[0069] where P a ≧P o where a and b are integers between 1 and 10. a , P o All combinations of pitches from 1x (1x) to 10x (10x) are considered, which allows evaluation of moire occurrence over a wide range considering integer multiple pitches. And a certain P a , P o P of all combinations of a and b changed for the combination of m The largest P m P mx is.

[0070] Figure 4 shows D oThe protruding height of the unit optical elements 35c from the support layer 35a shown in is preferably 1 μm or more and 10 μm or less. If it is smaller than this, the processing accuracy may deteriorate and stripes may become visible, while if it is larger than this, moire is likely to occur between the light absorbing parts 34 and the unit optical elements 35c.

[0071] In the above embodiment, multiple unit optical elements 35c are arranged continuously without any gaps, but this is not limited to this, and a gap may be provided between adjacent unit optical elements 35c, and the surface of the support layer 35a may be exposed in this area.

[0072] In this embodiment, the main refractive surface 35d of the unit optical element 35c is linear in the cross section shown in FIGS. 4 and 5, but is not limited to this, and may be concave or convex curved or bent in the cross section. Furthermore, the main refraction surfaces 35d and the rise surfaces 35e may be roughened, which scatters light and suppresses the occurrence of moire. There are no particular limitations on the method for roughening the main refraction surfaces 35d and the rise surfaces 35e, but examples include blasting the unit optical elements directly or blasting a mold for molding the unit optical elements. The plurality of unit optical elements 35c do not necessarily all have the same shape, and may be changed as appropriate.

[0073] In addition, although the support layer 35a is provided in the light-emitting-side light control layer 35 in this embodiment, the support layer 35a is not necessarily provided. For example, as shown in Fig. 6, a modified light-emitting-side light control layer 35', the optical element layer 35b may be formed directly on the base material layer 31. In this case, the surface of the base layer 31 that forms the interface with the optical element layer 35b can be made rough, and the refractive index of the base layer 31 and the refractive index of the optical element layer 35b can be made different. This allows the rough surface to scatter light, making it possible to suppress the occurrence of moire.

[0074] The support layer 35a and the optical element layer 35b (unit optical elements 35c) of the light-emitting side light control layer 35 can be made of the same materials as the base material layer 31 and the light transmitting portion 33 described above.

[0075] The optical sheet 30 can be produced, for example, as follows. First, the light-transmitting portion 33 is formed on one surface of the base layer 31. To do this, a base sheet that will become the base layer 31 is inserted between a mold roll having a surface shape that can transfer the shape of the light-transmitting portion 33 and a nip roll that is arranged opposite the mold roll. At this time, a gap is provided between the mold roll and the nip roll, which becomes the base portion 32a. Then, the mold roll and nip roll are rotated while a composition that will form the light-transmitting portion is supplied between the base sheet and the mold roll. As a result, the composition that will form the light-transmitting portion fills grooves (which have a shape that is the inverse of the shape of the light-transmitting portion) that correspond to the light-transmitting portion formed on the surface of the mold roll, and the composition conforms to the surface shape of the mold roll.

[0076] Examples of the composition constituting the light transmitting portion include ionizing radiation curable resins such as epoxy acrylate, urethane acrylate, polyether acrylate, polyester acrylate, and polythiol.

[0077] The composition that constitutes the light-transmitting portion, which is sandwiched between the mold roll and the substrate sheet and filled therein, is irradiated with light from the substrate sheet side using a light irradiation device to harden the composition. This hardens the composition and fixes its shape. Then, the substrate layer 31 and the molded light-transmitting portion 33 are released from the mold roll by a release roll.

[0078] Next, the light absorbing portions 34 are formed. To form the light absorbing portions 34, first, the gaps (grooves) between the light transmitting portions 33 formed above are filled with a composition that will form the light absorbing portions. Thereafter, excess composition is scraped off with a doctor blade or the like. Then, the remaining composition is cured by irradiating it with ultraviolet light from the light transmitting portion 33 side, thereby forming the light absorbing portions 34.

[0079] The material used as the light absorbing portion is not particularly limited, but examples thereof include compositions in which colored light absorbing particles are dispersed in a photocurable resin such as urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate, and butadiene (meth)acrylate.

[0080] Instead of dispersing light-absorbing particles, the entire light-absorbing portion can be colored with a pigment or dye. When light-absorbing particles are used, light-absorbing colored particles such as carbon black are preferably used, but are not limited thereto. Colored particles that selectively absorb specific wavelengths in accordance with the characteristics of the image light may also be used. Specific examples include organic fine particles colored with metal salts such as carbon black, graphite, and black iron oxide, dyes, pigments, etc., and colored glass beads. Colored organic fine particles are particularly preferred from the standpoints of cost, quality, availability, etc. The average particle diameter of the colored particles is preferably 1.0 μm or more and 20 μm or less, more preferably 1.0 μm or more and 10 μm or less, and even more preferably 1.0 μm or more and 4.0 μm or less. Here, the term "average particle diameter" refers to the diameter obtained by observing 100 light-absorbing particles under an electron microscope, measuring their diameters, and calculating the arithmetic mean.

[0081] Meanwhile, separately from the optical function layer 32, an output-side light control layer 35 is prepared by laminating an optical element layer 35b on one surface of a support layer 35a. This can be prepared in the same manner as the method for laminating the light transmission portions 33 on the base material layer 31 in the optical function layer 32. However, if the bias angle α2 is set to an angle other than 0°, it is preferable that the grooves for molding the unit optical elements 35c in the roll mold for forming the optical element layer 35b are formed in a spiral shape (thread groove shape) along the outer circumferential surface of the roll mold. This allows for an appropriate bias angle α2 to be imparted from the standpoints of precision and efficiency.

[0082] Then, the surface of the base material layer 31 opposite the side on which the optical function layer 32 is arranged and the surface of the support layer 35a of the light-emitting side light control layer 35 opposite the side on which the optical element layer 35b is arranged are bonded together with an adhesive to obtain the optical sheet 30.

[0083] 1 to 3, the reflective sheet 39 of the surface light source device 20 will be described. The reflective sheet 39 is a member that reflects light emitted from the rear surface of the light guide plate 21 and causes the light to enter the light guide plate 21 again. The reflective sheet 39 can preferably be one that enables so-called specular reflection, such as a sheet made of a material with high reflectivity such as metal, or a sheet that includes a thin film made of a material with high reflectivity (for example, a metal thin film) as a surface layer.

[0084] The functional film 40 is disposed on the light-emitting side of the liquid crystal panel 15, and is a layer having the function of improving the quality of the image light and protecting the image source unit 10. Examples of such films include an anti-reflection film, an anti-glare film, a hard coat film, a color correction film, and a light diffusion film, and these may be used alone or in combination.

[0085] Next, the operation of the image source unit 10 having the above-described configuration will be described with reference to examples of optical paths. However, these optical path examples are conceptual examples for the purpose of explanation and do not strictly represent the degree of reflection or refraction.

[0086] First, as shown in Fig. 2, light emitted from the light source 25 enters the light guide plate 21 from a light incident surface, which is a side surface (end surface) of the light guide plate 21. As an example, Fig. 2 shows the light L incident from the light source 25 to the light guide plate 21. 21 , L 22 An example of a light path is shown.

[0087] As shown in FIG. 2, light L incident on the light guide plate 21 21 , L 22 is repeatedly totally reflected by the light-emitting side surface of the light guide plate 21 and the rear surface on the opposite side thereof due to the difference in refractive index with air, and travels in the light guide direction (downward in the plane of FIG. 2).

[0088] However, a rear optical element 23 is disposed on the rear surface of the light guide plate 21. Therefore, as shown in FIG. 21 , L 22 The light may be redirected by the rear optical element 23 and enter the light output surface and the rear surface at an angle of incidence less than the critical angle for total reflection. In this case, the light may exit the light guide plate 21 from the light output surface and the rear surface opposite thereto.

[0089] Light L emitted from the light output surface 21 , L 22 The light emitted from the rear surface of the light guide plate 21 is reflected by the reflective sheet 39 disposed on the rear surface of the light guide plate 21, enters the light guide plate 21 again, and travels through the light guide plate 21.

[0090] Light traveling within light guide plate 21 and light that is redirected by rear optical element 23 and reaches the light output surface at an incident angle less than the critical angle for total reflection are generated in each region along the light guide direction within light guide plate 21. As a result, light traveling within light guide plate 21 is gradually emitted from the light output surface. This makes it possible to uniformize the light amount distribution along the light guide direction of the light that is emitted from the light output surface of light guide plate 21.

[0091] The light emitted from the light guide plate 21 then reaches the light diffusion plate 26, where the uniformity is increased. The light is then diffused or concentrated as necessary by the prism layer 27, and the light that has exited the prism layer 27 reaches the reflective polarizing plate 28. Here, the light polarized in the direction along the transmission axis of the reflective polarizing plate 28 passes through the reflective polarizing plate 28 and heads toward the optical sheet 30. On the other hand, light polarized in the direction along the reflection axis of reflective polarizer 28 is reflected as shown by the dotted arrow in Figure 2 and returned to the light guide plate 21 side. The returned light is reflected by light guide plate 21, rear optical element 23, or reflective sheet 39 and travels again toward reflective polarizer 28. The polarization direction of some of the light changes during this reflection, and some of this light is transmitted through reflective polarizer 28. The other light is returned again to the light guide plate side. In this way, the light reflected by reflective polarizer 28 can also be transmitted through reflective polarizer 28 by repeated reflection. This increases the utilization efficiency of light from light source 25. Here, the polarization direction of the light emitted from the reflective polarizer 28 is aligned with the transmission axis of the lower polarizer 14, and the light is in a polarized state that is transmitted through the lower polarizer 14.

[0092] The light emitted from the reflective polarizing plate 28 reaches the optical sheet 30. The light incident on the optical sheet 30 travels along the following optical path. An example of the optical path in the optical sheet 30 is shown in FIG.

[0093] With respect to the direction in which the light transmitting portions 33 and the light absorbing portions 34 are alternately arranged (the vertical direction in this embodiment), the light L 21 , light L 22 , and the light L shown in FIG. 71 , light L 72 As shown in the figure, the light is directed toward an interface 34a, which is the upper side of the light absorbing portion 34, among the interfaces between the light transmitting portion 33 and the light absorbing portion 34. The light is then totally reflected at the interface 34a, becoming light that travels obliquely upward toward the viewer, thereby controlling the light in the desired direction. At this time, if an interface 34b, which is the lower side of the light absorbing portion 34 among the interfaces between the light transmitting portion 33 and the light absorbing portion 34, is inclined obliquely upward toward the viewer, the light L 21 , light L 22 , light L 71 , light L 72 The light absorbing portion 34 is less likely to obstruct the progression of such light, and more light can be guided in the desired direction.

[0094] Also, the L shown in Figure 7 73travels obliquely upward toward the observer and travels at an angle that transmits through the interface 34b between the light-transmitting portion 33 and the light-absorbing portion 34 without being totally reflected at the interface 34b, and is therefore transmitted through the interface 34b and absorbed by the light-absorbing portion 34. This makes it possible to efficiently absorb and block light emitted at a viewing angle equal to or greater than a desired angle, and furthermore to efficiently control the direction of travel of the light. Furthermore, since such light is likely to enter the liquid crystal panel and cause defects such as a decrease in contrast and color inversion, or a decrease in quality, it is possible to absorb such light.

[0095] The light transmitted through the optical function layer 32 is further changed in direction by the optical element layer 35b. Specifically, in this embodiment, the light L shown in FIG. 71 , light L 72 As shown, the light L 71 , L 72 is further refracted upward and emitted, which allows the light emission range to be further shifted upward.

[0096] Therefore, as shown in FIG. 8, the optical sheet 30 of this embodiment can more efficiently increase the light output angle in the vertically upward direction with the optical sheet 30 (B in FIG. 8) compared to the case where there is no light-output-side light control layer 35 (A in FIG. 8). In FIG. 8, the horizontal axis represents the light output angle with respect to the normal to the sheet surface in the vertical direction, with positive representing upward and negative representing downward. The vertical axis represents the relative brightness when a certain brightness is set to 100%. Adjusting the light output angle in this way using only the optical function layer is difficult, and even if it is adjusted, problems such as a decrease in brightness often occur. In contrast, by further providing an optical element layer 35b as in the optical sheet 30, it is possible to efficiently control the light output angle. The optical element layer 35b for controlling light in this manner has a simple structure as described above, and is effective despite its simple structure. In this embodiment, the above θ 11 , and θ 12 (See Figure 5) 11 <θ 12This allows the viewing angle to be controlled over a wider range.

[0097] Light emitted from the optical sheet 30 is incident on the lower polarizer 14 of the liquid crystal panel 15. The lower polarizer 14 transmits one polarized component of the incident light and absorbs the other polarized component. The light that passes through the lower polarizer 14 is selectively transmitted through the upper polarizer 13 depending on the state of the electric field applied to each pixel. In this way, the liquid crystal panel 15 selectively transmits light from the surface light source device 20 pixel by pixel, allowing a viewer of the liquid crystal display device to view an image. At this time, the image light is provided to the viewer via the functional film 40, improving the quality of the image.

[0098] Fig. 9 is a diagram for explaining a second embodiment, and corresponds to Fig. 5. In this embodiment, an output-side light control layer 135 is used as the light control layer instead of the output-side light control layer 35. Since the other parts are the same as those of the image source unit 10 described above, the configuration and function of the output-side light control layer 135 will be described here.

[0099] The light-emitting-side light control layer 135 controls the direction of light emitted from the optical function layer 32 and emits the light. Therefore, the light-emitting-side light control layer 135 is configured to have a support layer 35a and an optical element layer 135b. The support layer 35a is the same as the support layer 35a of the light-emitting-side light control layer 35 described above.

[0100] The optical element layer 135b is a layer that changes the direction of light emitted from the optical function layer 32, and is formed by arranging a plurality of unit optical elements 135c on the surface of the support layer 35a opposite to the optical function layer 32 side.

[0101] In this embodiment, the unit optical element 135c specifically has the following structure. The unit optical element 135c is a triangular prism having a triangular cross section that protrudes toward the side opposite the optical function layer 32, and is configured as a protrusion having the cross section and whose ridgeline extends parallel to the extension direction of the light-transmitting portion 33 and the light-absorbing portion 34 (bias angle α2=0°) or at a bias angle (bias angle α2≠0°). A plurality of unit optical elements 135c are arranged in a direction different from the extension direction. The concept of the bias angle α2 between the unit optical element 135c and the light-transmitting portion 33 is the same as that of the unit optical element 35c described above.

[0102] 9, each unit optical element 135c has a main refraction surface 135d and a rise surface 135e. The main refraction surface 135d and the rise surface 135e form two surfaces of a triangular prism, and the other surface overlaps the support layer 35a and is fixed to the support layer 35a.

[0103] In this embodiment, the main refraction surface 135d is a refraction surface that, in the same position as in FIG. 1, changes the angle of light emitted upward from the optical function layer 32 so that it approaches the front direction. This allows the vertical light emission angle to be adjusted to a desired direction. In this case, the main refraction surface 135d is inclined in a direction away from the optical function layer 32 as it extends downward (here, this direction is referred to as the negative (-) direction). Therefore, in one unit optical element 135c, the main refraction surface 135d is on the top and the rise surface 135e is on the bottom. The inclination angle of the main refractive surface 135d is θ with respect to the normal direction of the light output surface of the optical function layer 32 as shown in FIG. 31 The angle is

[0104] θ 31 Specifically, the angle θ is preferably greater than or equal to -89° and less than -45° (the absolute value of the tilt angle is greater than 45° and less than or equal to 89°). This allows for reliable control of light to improve brightness in a desired direction (light output angle control). 31 If θ is equal to or larger than −45°, there is a risk that a large amount of light will be totally reflected by the main refractive surface 135d and will not be emitted. 31If the angle is smaller than -89°, the surface will hardly function as a main refractive surface. More preferred θ 31 is between -89° and -80° (the absolute value of the tilt angle is between 80° and 89°). 31 By setting the value in this range, the rise surface 135e becomes small, and stray light due to the rise surface 135e can be reduced.

[0105] Other preferred aspects of the unit optical element 135c in terms of shape can be considered to be similar to those of the unit optical element 35c described above.

[0106] Next, we will explain the operation of the image source unit equipped with the output-side light control layer 135. An example of the light path is shown in Figure 10. Note that the light paths in other parts are the same as those in the image source unit 10 described above, so explanations will be omitted here.

[0107] The direction of the light transmitted through the optical function layer 32 is further changed by the optical element layer 135b. Specifically, in this embodiment, the light L shown in FIG. 101 , light L 102 As shown in the figure, the light L 101 , L 102 The light is refracted so that it approaches the front side and is emitted. This allows the light emission angle to be controlled in the desired direction.

[0108] Therefore, as shown in FIG. 11, an optical sheet including the light-emitting-side light control layer 135 can shift the viewing angle more efficiently (FIG. 11C) than an optical sheet without the light-emitting-side light control layer 135 (FIG. 11A). In FIG. 11, the horizontal axis represents the light-emitting angle relative to the normal to the sheet surface in the vertical direction, with positive representing upward and negative representing downward. The vertical axis represents the relative brightness when a certain brightness is set to 100%. Adjusting the light-emitting angle in this way using only the optical functional layer is difficult, and even if it is possible, problems such as a decrease in brightness often occur. In contrast, by further including the light-emitting-side light control layer 135, the viewing angle can be controlled more efficiently. The optical element layer 135b for controlling light in this manner has a simple configuration as described above, and is effective with such a simple configuration.

[0109] 12 is a diagram illustrating the third embodiment, and is an exploded perspective view of image source unit 210 including optical sheet 230. In this embodiment, optical sheet 30 described above is disposed closer to the light incident side (light guide plate 21 side) than optical sheet 230, and the two optical sheets, optical sheet 30 and optical sheet 230, form light control member 229. For ease of understanding in this embodiment, optical sheet 30 may be referred to as first optical sheet 30, and optical sheet 230 may be referred to as second optical sheet 230.

[0110] Fig. 13 shows a portion of an exploded cross-sectional view of image source unit 210 taken along line XIII-XIII (a line running in the vertical direction) in Fig. 12, and Fig. 14 shows an exploded cross-sectional view of image source unit 210 taken along line XIV-XIV (a line running in the horizontal direction) in Fig. 12. Note that the vertical direction and horizontal direction referred to here refer to the orientation in which light control member 229 is placed in a display device and this display device is used. Although detailed description will be omitted, such an image source unit 210 is also housed in a housing (not shown) together with normal equipment required for operation as the image source unit 210, such as a power supply for operating the image source unit 210 and electronic circuits for controlling the image source unit 210, to form a display device. In this embodiment, a liquid crystal image source unit will be described as one form of the image source unit, and a liquid crystal display device will be described as one form of the display device. The image source unit 210 will be described below.

[0111] The image source unit 210 includes a liquid crystal panel 15, a surface light source device 220, and a functional film 40. In this embodiment, a first optical sheet 230 and a light control member 229 including the first optical sheet 230 are provided in the surface light source device 20. Figures 12 to 14 also show the orientation of the display device when it is installed. Here, the liquid crystal panel 15 and the functional film 40 can be considered to be similar to the image source unit 10 of the first embodiment, and therefore the same reference numerals are used here and the description thereof will be omitted.

[0112] The surface light source device 220 is an illumination device that is disposed on the opposite side of the liquid crystal panel 15 from the viewer side, and that emits planar light toward the liquid crystal panel 15. As can be seen from FIGS. 12 to 14 , the surface light source device 220 of this embodiment is configured as an edge-light type surface light source device, and includes a light guide plate 21, a light source 25, a light diffusion plate 26, a prism layer 27, a reflective polarizing plate 28, a light control member 229, and a reflection sheet 39. Here, other than the light control member 229, it can be considered that the components are the same as the surface light source device 20 included in the image source unit 10 of the first embodiment, so the same reference numerals are used and the description will be omitted here.

[0113] In this embodiment, the light control member 229 is configured to include a first optical sheet 30 and a second optical sheet 230. Of these two optical sheets, the first optical sheet 30 is disposed on the light guide plate 21 side, and the second optical sheet 230 is disposed on the liquid crystal panel 15 side. Here, the first optical sheet 30 can be considered to be the same as the optical sheet 30 included in the surface light source device 20, and therefore the same reference numerals are used and a description thereof will be omitted.

[0114] Fig. 15 shows an enlarged view of a portion of the second optical sheet 230 taken from the perspective of Fig. 14. As can be seen from Figs. 12 to 15, the second optical sheet 230 includes a base layer 231 formed in a sheet shape, an optical function layer 232 provided on one surface of the base layer 231 (the surface on the first optical sheet 30 side in this embodiment), and an output-side light control layer 235 as a light control layer disposed on the other surface of the base layer 231 (the surface on the liquid crystal panel 15 side in this embodiment). Here, the base layer 231 can be considered to be the same as the base layer 31 of the optical sheet 30 .

[0115] The optical function layer 232 is a layer laminated on one surface of the base layer 231 (in this embodiment, the surface on the first optical sheet 30 side), and is configured to have light-transmitting portions 233 and light-absorbing portions 234. The optical function layer 232 has a cross section shown in Figures 14 and 15 and has a shape that extends toward the back / front of the page (in this embodiment, the vertical direction when the image source unit 210 is viewed from the front), and the light-transmitting portions 233 and light-absorbing portions 234 are alternately arranged along the layer surface in a direction different from the extending direction (in this embodiment, the horizontal direction).

[0116] The light-transmitting portion 233 is a portion whose main function is to transmit light, and in this embodiment, in the cross section shown in Figures 14 and 15, it is an element having an approximately trapezoidal cross-sectional shape with a long lower base on the base layer 231 side and a short upper base on the opposite side (the first optical sheet 30 side). The light transmitting portions 233 extend in one direction (vertical direction in this embodiment) while maintaining the cross section along the layer surface of the base layer 231, and are arranged at intervals in a direction different from the extending direction (horizontal direction in this embodiment). A gap (groove) having a substantially trapezoidal cross section is formed between adjacent light transmitting portions 233. Therefore, the gap (groove) has a trapezoidal cross section with a long bottom base on the top side of the light transmitting portion 233 (first optical sheet 30 side) and a short top base on the bottom side of the light transmitting portion 233 (base layer 231 side), and the light absorbing portions 234 are formed by filling this gap with a necessary material, which will be described later. In this embodiment, a plurality of light transmitting portions 233 are connected on their lower bottom side (base layer 231 side) by a sheet-like base portion 232a. With this configuration, the extension direction of the light transmitting portions 33 of the first optical sheet 30 and the extension direction of the light transmitting portions 233 of the second optical sheet 230 are arranged to intersect when the optical sheets are viewed from the front.

[0117] The refractive indexes of the light-transmitting portions 233 and the light-absorbing portions 234 can be considered to be similar to those of the light-transmitting portions 33 and the light-absorbing portions 34 of the optical sheet 30 .

[0118] The optical function layer 232 is not particularly limited, but may have, for example, the following shape: Fig. 16 shows a further enlarged view of a part of Fig. 15 (the upper part of Fig. 15).

[0119] θ shown in Fig. 16 41 θ is the angle between an interface 234a on one of the left and right sides in the horizontal direction, among the interfaces between the light transmitting portion 233 and the light absorbing portion 234, when the second optical sheet 230 is in the position shown in FIG. 12, and the normal to the layer surface of the optical function layer 232. 42 is the angle between the interface 234b on the other side of the interface between the light-transmitting portion 233 and the light-absorbing portion 234 in the same posture, when the second optical sheet 230 is in the posture shown in Figure 12, and the normal to the layer surface of the optical function layer 232. In this embodiment, θ 41 , θ 42 is preferably 0° or more and 10° or less. 41 , and θ 42 The relationship between the magnitudes of the angles can be set as needed.

[0120] Also, in Figure 15, P b The pitch of the light transmitting portion 233 and the light absorbing portion 235 represented by D is preferably 20 μm or more and 100 μm or less, and more preferably 30 μm or more and 100 μm or less. b The thickness of the light absorbing portion 234 is preferably 50 μm or more and 150 μm or less, and more preferably 60 μm or more and 150 μm or less. By setting the thickness within these ranges, it is possible to achieve a more appropriate balance between light transmission and light absorption.

[0121] In the present embodiment, an example has been shown in which the interface between the light transmitting portion 233 and the light absorbing portion 234 is linear in cross section, but the present invention is not limited to this and may be a broken line, a convex curve, a concave curve, etc. Furthermore, the cross-sectional shapes of the plurality of light transmitting portions 233 and light absorbing portions 234 may be the same or may be different cross-sectional shapes with regularity.

[0122] In the above, an example has been described in which the extending direction of the light-transmitting portions 233 and the light-absorbing portions 235 is vertical, but from the viewpoint of suppressing the occurrence of moire, it is preferable that the extending direction of the light-transmitting portions 233 and the light-absorbing portions 234 form an angle (bias angle α3) with respect to the arrangement direction of the pixels of the liquid crystal layer 12 when viewed from the front of the image source unit. The specific angle of this bias angle α3 is not particularly limited as long as it can prevent the occurrence of moire, but it is preferable that it be between 1° and 10°.

[0123] Next, the light-emitting side light control layer 235 will be described. The light-emitting side light control layer 235 controls the direction of light emitted from the optical function layer 232 and emits the light. In this embodiment, the light-emitting side light control layer 235 controls the direction of the light controlled by the optical function layer 232 so that the emitted light has a desired emission angle. More specifically, the light emitted from the outer periphery of the sheet is controlled so that it travels in a direction inclined toward the center of the sheet from the normal direction.

[0124] Therefore, the light-emitting side light control layer 235 is configured to include a support layer 235a and an optical element layer 235b. The support layer 235 a is a transparent sheet-like member that functions as a support for the optical element layer 235 b , and can be considered to be similar to the support layer 35 a of the optical sheet 30 .

[0125] The optical element layer 235b is a layer that changes the direction of light emitted from the optical function layer 232, and is formed by arranging a plurality of unit optical elements 235c on the surface of the support layer 235a opposite to the optical function layer 232 side. In this embodiment, the optical element layer 235b is disposed on the support layer 235a, but this is not limiting, and the optical element layer 235b may be disposed directly on the surface of the base layer 231 opposite to the side on which the optical function layer 232 is disposed. In this case, the light-emitting side light control layer does not have a support layer and is composed only of the optical element layer 235b.

[0126] In this embodiment, the optical element layer 235b is a layer that changes the direction of light controlled by the optical function layer 232 so that the light emitted to the outer periphery of the sheet in the direction in which the multiple unit optical elements 235c are arranged (horizontal in this embodiment) is emitted in a direction tilted toward the center rather than the normal direction of the sheet. 14 to 16, each unit optical element 235c is a triangular prism having a triangular cross section that protrudes toward the side opposite to the optical function layer 232, and is configured as a protrusion having the cross section and whose ridgeline extends in the same direction as the extension direction of the light transmitting portions 233 and the light absorbing portions 234 (bias angle α4=0°) or at an angle (bias angle α4≠0°) when viewed from the front of the optical sheet (extending in the vertical direction in this embodiment). A plurality of unit optical elements 235c are arranged in a direction different from the extension direction (horizontal direction in this embodiment). When the ridgelines of the unit optical elements 235c are configured to extend at an angle relative to the extension direction of the light-transmitting portions 233 and the light-absorbing portions 234 in a front view of the optical sheet (bias angle α4 ≠ 0°), it is preferable that the extension direction of the light-transmitting portions 233 of the optical function layer 232 and the extension direction of the ridgelines of the unit optical elements 235c are relatively inclined, with 0° < α4 ≦ 45°, in a front view of the light control member 229. This prevents moiré from occurring due to the arrangement structure of the light-transmitting portions 233 and the light-absorbing portions 234 and the arrangement structure of the unit optical elements 235c. If α4 is greater than 45°, the efficiency of light direction control by the unit optical elements 235c decreases. A more preferable angle is 1° ≦ α4 ≦ 10°.

[0127] 15, in the optical element layer 235b of this embodiment, in the direction in which the unit optical elements 235c are arranged, the cross-sectional shapes of the unit optical elements 235c are symmetrical between one end side and the other end side of the optical element layer 235b across the center of the sheet, and a portion having no unit optical elements 235c is provided in the center of the sheet between the one end side and the other end side (portion W3 in FIG. 15). In other words, this portion is flat, and the angle of the main refractive surface of the unit optical element with respect to the normal to the sheet surface (θ in FIG. 16) is 51 ) is 90°. Note that such a portion without unit optical elements does not necessarily need to be provided, and symmetrical unit optical elements 235c may be configured adjacent to each other across the center of the sheet. However, if adjacent unit optical elements are symmetrically positioned across the center of the sheet, a line may appear at the boundary between them, which may be visible. Therefore, it is preferable that at least the center of the sheet is flat and free of unit optical elements. To prevent the line from appearing at the center of the sheet, for example, when a mold for forming the optical element layer 235 is produced by cutting, the surface of the mold in the portion that will become the center of the sheet may be overlapped so that the cutting tool straddles this portion.

[0128] The array of such a plurality of unit optical elements 235c can also be configured to resemble, for example, a linear Fresnel lens.

[0129] 16, the unit optical element 235c has a main refraction surface 235d and a rise surface 235e. The main refraction surface 235d and the rise surface 235e form two surfaces of a triangular prism, and the other surface overlaps the support layer 235a and is fixed to the support layer 235a.

[0130] In this embodiment, the main refraction surface 235d is a refraction surface that, in the orientation shown in FIGS. 12 to 16, redirects light emitted from the optical function layer 232 in the horizontal direction so that it travels at an angle inclined toward the center with respect to the sheet normal. This allows light emitted from the screen edge to travel toward the center in the direction in which the unit optical elements 235c are arranged (horizontal in this embodiment), so that the light from the screen edge is directed toward the observer who is looking directly at the center of the screen, allowing the observer to view the light emitted from the screen edge brightly. In this case, when focusing on one main refraction surface 235d, it is inclined in a direction away from the optical function layer 232 (in a more protruding direction) as it approaches the sheet center. Therefore, when focusing on one unit optical element 235c, the main refraction surface 235d is located on the sheet outer periphery side, and the rise surface 235e is located on the sheet center side. The inclination of the main refraction surface 235d is θ , as shown in FIG. 16, with respect to the normal to the optical function layer 232. 51 The angle is

[0131] θ 51 Specifically, the angle θ is preferably greater than 45° and less than 90° (the absolute value of the tilt angle of the main refractive surface is greater than 45° and less than 90°). This allows for reliable control of light to improve brightness in a desired direction (control of the light output angle). 51 If θ is 45° or less, there is a risk that a large amount of light will be totally reflected by the main refractive surface 235d and will not be emitted. 51 If the angle is 90° or more, the function as a main refractive surface can hardly be exhibited. 51 is between 80° and 89°. 51 By setting the value in this range, the rise surface 235e becomes small, and the generation of stray light due to the rise surface 235e can be reduced. And this θ 51 It is preferable that the angle θ be different between the unit optical elements 235c on the central side and the unit optical elements 235c on the outer periphery in the direction in which the unit optical elements 235c are arranged (horizontal direction in this embodiment). This allows for more accurate control of light. More preferably, the angle θ from the unit optical elements 235c on the central side to the unit optical elements 235c on the outer periphery 51 This allows for efficient control of the direction of light traveling toward the center.

[0132] The rise surface 235e is a surface required to form the main refractive surface 235d. Fig. 16 shows θ 52 The inclination angle of the rise surface 235e, represented by θ, is preferably 80° or more and 100° or less with respect to the direction along the light output surface of the optical function layer 232. From the viewpoint of manufacturing, it is more preferably 80° or more and 90° or less. 52 If the angle is less than 80° or more than 100°, there is a risk that stray light from the rise surface 235e will increase.

[0133] The apex angle of the unit optical element 235c is the above θ 51 and θ 52 The angle is naturally determined from the angle of the angle, but it is preferably 45° or more and less than 90°.

[0134] Figure 15 shows P p The pitch of the unit optical elements 235c shown in is preferably small, from the viewpoint that even if moire occurs, it is difficult to see by reducing the moire pitch. Specifically, the pitch P p It is preferable that the thickness is 50 μm or less. In addition, since the optical function layer 232 is more difficult to manufacture than the optical element layer 235b, the pitch P b (See FIG. 15) and the pitch P of the unit optical elements 235c p It is desirable that P is smaller. p HA P b It is most desirable that the p , P b / 2, P b / 3, P b When the pitch is set to a constant value, such as 1 / 4, the ends of the light transmitting portions 233 and the ends of the unit optical elements 235c should not coincide with each other as much as possible. p and P b It is preferable that the least common multiple is large. On the other hand, when the unit optical element 235c becomes small, the accuracy decreases. p is preferably 10 μm or more.

[0135] More preferably, the arrangement pitch of the light transmitting portions 233 is P b (μm), the arrangement pitch of the unit optical elements 235c is P p (μm), P mx (μm) is 10000 (μm) or less. mx can be considered in the same way as above.

[0136] Figure 15 shows D p The protruding height of the unit optical elements 235c from the support layer 235a shown in is preferably 1 μm or more and 10 μm or less. If it is smaller than this, the processing accuracy may deteriorate and stripes may become visible, whereas if it is larger than this, moire is likely to occur between the light absorbing parts 234 and the unit optical elements 235c.

[0137] In the above embodiment, multiple unit optical elements 235c are arranged continuously without any gaps, but this is not limited to this, and an embodiment may also be possible in which a gap is provided between adjacent unit optical elements 235c and the surface of the support layer 235a is exposed in this portion.

[0138] In this embodiment, the main refractive surface 235d of the unit optical element 235c is linear in the cross section shown in FIGS. 14 to 16, but is not limited to this and may be concave or convex curved or bent. Furthermore, the main refraction surface 235d and the rise surface 235e may be roughened, which scatters light and suppresses the occurrence of moire. There are no particular limitations on the method for roughening the main refraction surface 235d and the rise surface 235e, but examples include blasting the unit optical elements directly or blasting a mold for molding the unit optical elements. The plurality of unit optical elements 235c do not necessarily all have the same shape, and may be changed as appropriate.

[0139] Furthermore, in this embodiment, the support layer 235a is provided on the output-side light control layer 235, but as described above, the support layer 235a is not necessarily provided, and the optical element layer 235b may be formed directly on the base material layer 231. In this case, the surface of the base material layer 231 that forms the interface with the optical element layer 235b can be made a rough surface, and the refractive index of the base material layer 231 and the refractive index of the optical element layer 235b can be made different. In this way, the rough surface scatters light, making it possible to suppress the occurrence of moire. Furthermore, the light-emitting-side light control layer does not necessarily have to be integral with the base layer or the optical functional layer, but may be provided separately. Therefore, an air layer may be formed between the light-emitting-side light control layer and the base layer or the optical functional layer, or another functional layer may be disposed therebetween.

[0140] The support layer 235a and the optical element layer 235b (unit optical elements 235c) of the light-emitting side light control layer 235 can be made of the same materials as the support layer 35a and the optical element layer 35b of the optical sheet 30 described above.

[0141] The second optical sheet 230 can also be manufactured in the same manner as the optical sheet 30, as described above.

[0142] Next, the operation of the image source unit 210 having the above-described configuration will be described with reference to an example of an optical path. However, this example of an optical path is conceptual for the purpose of explanation and does not strictly represent the degree of reflection or refraction. Furthermore, the optical path from the light source 25 to the light control member 229 is the same as the example of an optical path described for the image source unit 10 above, and therefore will not be described again (see FIG. 2).

[0143] The light incident on the light control member 229 first enters the first optical sheet 30 and travels along the following optical path: An example of the optical path in the first optical sheet 30 is shown in FIG.

[0144] With respect to the direction in which the light transmitting portions 33 and the light absorbing portions 34 are alternately arranged (the vertical direction in this embodiment), the light L 171 , light L 172 As shown in Fig. 1, the light is directed toward an interface 34a, which is the upper side of the light absorbing portion 34, among the interfaces between the light transmitting portion 33 and the light absorbing portion 34. The light is then totally reflected at the interface 34a, and becomes light directed obliquely upward toward the observer, thereby controlling the light in the desired direction. At this time, if an interface 34b, which is the lower side of the light absorbing portion 34 among the interfaces between the light transmitting portion 33 and the light absorbing portion 34, is inclined obliquely upward toward the observer side, the light L 171 , light L 172 The light absorbing portion 34 is less likely to obstruct the progression of such light, and more light can be guided in the desired direction.

[0145] Also, the light L shown in FIG. 173 is obliquely upward toward the observer and travels at an angle that transmits through the interface 34b between the light-transmitting portion 33 and the light-absorbing portion 34 without being totally reflected at the interface 34b, and is therefore transmitted through the interface 34b and absorbed by the light-absorbing portion 34. This makes it possible to efficiently absorb and block light emitted at an emission angle equal to or greater than a desired angle, and furthermore to efficiently control the traveling direction of the light. Furthermore, since such light is likely to enter the liquid crystal panel and cause defects such as a decrease in contrast and color inversion, as well as a decrease in image quality, it is possible to absorb such light.

[0146] The direction of the light transmitted through the optical function layer 32 is further changed by the optical element layer 35b. Specifically, in this embodiment, the light L shown in FIG. 171 , light L 172 As shown, the light L 171 , L 172 is further refracted upward and emitted, which allows the light emission angle to be further shifted upward.

[0147] Therefore, even in the first optical sheet 30 of this embodiment, as shown in Fig. 8, the first optical sheet 30 (B in Fig. 8) can more efficiently increase the light output angle in the vertically upward direction compared to the case where there is no light output-side light control layer 35 (A in Fig. 8). Adjusting the light output angle in this manner is difficult using only the optical function layer 32, and even if it is adjusted, problems such as a decrease in brightness often occur. In contrast, by further providing an optical element layer 35b as in the first optical sheet 30, it becomes possible to efficiently control the light output angle. The optical element layer 35b for controlling light in this manner has a simple structure as described above, and is effective with such a simple structure.

[0148] The light emitted from the first optical sheet 30 reaches the second optical sheet 230. The light incident on the second optical sheet 230 travels along the following optical path. An example of the optical path in the second optical sheet 230 is shown in FIG.

[0149] With respect to the direction in which the light transmitting portions 233 and the light absorbing portions 234 are alternately arranged (the horizontal direction in this embodiment), the light L shown in FIG. 151 ~Light L 156 is totally reflected at the interface between the light transmitting portion 233 and the light absorbing portion 234, and the direction of the light is changed so as to approach the normal to the sheet surface. This makes it easier to control the light as desired in the optical element layer 235b.

[0150] light L 157 is light that originally travels in a direction close to the front direction in the horizontal direction, and passes through the light transmitting portion 233 without reaching the light absorbing portion 234.

[0151] Also, the light L shown in FIG. 158 is light that travels at a large angle to the front in the horizontal direction. This light travels at an angle that transmits through the interface between the light transmitting portion 233 and the light absorbing portion 234 without being totally reflected at the interface, and is therefore transmitted through the interface and absorbed by the light absorbing portion 234. This makes it possible to efficiently absorb and block light emitted at angles greater than a desired angle, and furthermore to efficiently control the direction of travel of the light. Furthermore, since such light is likely to enter the liquid crystal panel and cause problems such as a decrease in contrast and color inversion, it is possible to absorb such light.

[0152] The light transmitted through the optical function layer 232 is further changed in direction by the optical element layer 235b. Specifically, in this embodiment, the light L shown in FIG. 151 , light L 152 , light L 153 , light L 154 As described above, in the direction in which the unit optical elements 235c are arranged on the main refraction surface 235d (horizontal direction in this embodiment), light can be emitted so that it travels at an angle toward the center with respect to the normal to the sheet surface. Naohikari L 155 , L 156 , L 157 is transmitted through the portion not provided with the unit optical element 235c, so that the light is emitted in a direction close to the front in the horizontal direction and is provided to the observer in front as is.

[0153] Figures 18(a) and 18(b) are diagrams explaining the characteristics of light emitted from the sheet in the horizontal direction. In Figures 18(a) and 18(b), the horizontal axis represents the light emission angle relative to the normal to the sheet surface in the horizontal direction, with positive representing the right side and negative representing the left side relative to the front. The vertical axis represents the relative brightness when a certain brightness is set to 100%. 18(a) shows an example in which the light-emitting-side light control layer 235 is not provided. In this case, the light is emitted while the light-emitting angle is restricted by the optical function layer, so the light is emitted only in directions with a small inclination relative to the normal to the sheet surface (in the example of FIG. 18(a), only in directions in the range of approximately -30° to +30°). Therefore, when the screen is wide or when the screen is viewed from a slight angle, dark areas may appear, particularly at the outer periphery of the screen. In contrast, FIG. 18(b) shows an example in which an output-side light control layer 235 is provided, as in this embodiment. The unit optical elements 235c arranged at the sheet outer peripheral edge of the output-side light control layer 235 can be controlled to shift the peaks of the emission direction of light emitted from the unit optical elements 235c (C1) on one side of the sheet outer peripheral edge and the unit optical elements 235c (C2) on the other side toward the sheet surface normal (0° direction), as shown by C1 and C2 in FIG. 18(b). Furthermore, in the sheet center portion formed between the unit optical elements 235c at both outer peripheral edges and where no unit optical elements 235c are arranged, the light is emitted in a direction close to the sheet surface normal, as shown by D. This inclines the light emitted from the screen edge toward the viewer's viewing direction, preventing dark areas from appearing at the outer peripheral edge of the screen, even when the screen is wide or viewed from a slight angle. Such adjustment of the light output direction angle is difficult to achieve using only the optical function layer 232, and even if it is achieved, it often results in problems such as a decrease in brightness and the need for a more complex structure. In contrast, by providing the optical element layer 235b, as in the second optical sheet 230, it becomes possible to efficiently control the light output angle. The optical element layer 235b for controlling light in this manner has a simple configuration as described above, and is effective with such a simple configuration.

[0154] By transmitting light through such light control member 229, it becomes possible to emit light in a desired vertical direction while controlling the light emitted from the outer peripheral edge in the horizontal direction. Such control can be performed efficiently with a simple configuration.

[0155] The light emitted from the light control member 229 is incident on the lower polarizer 14 of the liquid crystal panel 15. The lower polarizer 14 transmits one polarized component of the incident light and absorbs the other polarized component. The light that has passed through the lower polarizer 14 is selectively transmitted through the upper polarizer 13 depending on the state of the electric field applied to each pixel. In this way, the liquid crystal panel 15 selectively transmits the light from the surface light source device 220 pixel by pixel, allowing the viewer of the liquid crystal display device to view an image. At this time, the image light is provided to the viewer via the functional film 40, improving the quality of the image.

[0156] In this embodiment, an example has been described in which the first optical sheet 30 and the second optical sheet 230 are combined and used as the light control member 229, but the two do not necessarily need to be combined, and the first optical sheet 30 and the second optical sheet 230 may each be used independently. Depending on the mode of light control, the optical sheets may be used separately or in combination.

[0157] Fig. 19 is a diagram illustrating the fourth embodiment, and is an exploded perspective view of image source unit 30 including optical sheet 330. Fig. 20 shows a portion of an exploded cross-sectional view of image source unit 310 cut along the line indicated by XX-XX in Fig. 19, and Fig. 21 shows a portion of an exploded cross-sectional view of image source unit 310 cut along the line indicated by XXI-XXI. Although detailed description will be omitted, such an image source unit 310 is also housed in a housing (not shown) together with normal equipment required for operation as the image source unit 310, such as a power supply for operating the image source unit 310 and electronic circuits for controlling the image source unit 310, to form a display device. In this embodiment, a liquid crystal image source unit will be described as one form of an image source unit, and a liquid crystal display device will be described as one form of a display device.

[0158] The image source unit 310 includes a liquid crystal panel 15, a surface light source device 320, and a functional film 40. In this embodiment, the optical sheet 330 is included in the surface light source device 320. Figures 19 to 21 also show the orientation of the display device when it is installed. Here, the liquid crystal panel 15 and the functional film 40 are the same as those in the image source unit 10, so they are denoted by the same reference numerals and the description thereof will be omitted.

[0159] The surface light source device 320 is an illumination device that is disposed on the opposite side of the liquid crystal panel 15 from the viewer side, and emits planar light toward the liquid crystal panel 15. As can be seen from FIGS. 19 to 21 , the surface light source device 320 of this embodiment is also configured as an edge-light type surface light source device, and includes a light guide plate 21, a light source 25, a light diffusion plate 26, a prism layer 27, a reflective polarizing plate 28, an optical sheet 330, and a reflective sheet 39. Here, since the components other than the optical sheet 330 are the same as those of the surface light source device 20 of the image source unit 10 described above, the components other than the optical sheet 330 are denoted by the same reference numerals as those of the surface light source device 30 and description thereof will be omitted. However, in this embodiment, the unit prisms 27a of the prism layer 27 extend in the light guiding direction of the light guide plate, and the plurality of unit prisms 27a are arranged in a direction perpendicular to the light guiding direction of the light guide plate.

[0160] Fig. 22 shows an enlarged view of a portion of the optical sheet 330 seen from the perspective of Fig. 20. As can be seen from Figs. 19 to 22, the optical sheet 330 includes a base layer 31 formed in a sheet shape, an optical function layer 332 provided on one surface of the base layer 31 (the surface on the light guide plate 21 side in this embodiment), and a light-entering-side light control layer 335 that functions as a light control layer. Here, the base layer 31 is the same as the base layer 31 provided on the optical sheet 30 of the image source unit 10 described above, and therefore the same reference numerals are used and the description thereof will be omitted.

[0161] The optical function layer 332 is a layer laminated on one surface of the base layer 31 (the surface on the light guide plate 21 side in this embodiment), and light transmitting portions 333 and light absorbing portions 334 are arranged alternately along the layer surface.

[0162] The optical function layer 332 has a cross section shown in Fig. 22 and has a shape extending toward the front / back of the page (the horizontal direction when the image source unit 310 is viewed from the front). That is, in the cross section shown in Fig. 22, the optical function layer 332 has light-transmitting portions 333 that are substantially trapezoidal, and light-absorbing portions 334 that are formed between two adjacent light-transmitting portions 333 and have a cross section that is substantially trapezoidal.

[0163] The light transmitting portions 333 are portions whose main function is to transmit light, and in this embodiment, in the cross sections shown in Figures 20 and 22, they are elements having a generally trapezoidal cross section with a long lower base on the base layer 31 side and a short upper base on the opposite side (the light guide plate 21 side, the light input-side light control layer 335 side). The light transmitting portions 333 extend in the above-mentioned direction (the horizontal direction in this embodiment) while maintaining the cross section along the layer surface of the base layer 31, and are arranged at intervals in a direction different from the extending direction (the vertical direction in this embodiment). Furthermore, a gap (groove) having a generally trapezoidal cross section is formed between adjacent light transmitting portions 333. Therefore, the gap (groove) has a trapezoidal cross section with a long lower base on the upper base side (light guide plate 21 side, light input-side light control layer 335 side) of the light transmitting portion 333 and a short upper base on the lower base side (liquid crystal panel 15 side, base material layer 31 side) of the light transmitting portion 333, and is filled with a necessary material described later to form the light absorbing portion 334. In this embodiment, adjacent light transmitting portions 333 are connected at their long lower base sides by sheet-like connecting portions 332a.

[0164] The materials and refractive indexes constituting the light transmitting portions 333 and the light absorbing portions 334 are considered to be the same as those of the light transmitting portions 33 and the light absorbing portions 334 of the optical sheet 30 described above.

[0165] 23, the angle θ that the interface between the light transmitting portion 333 and the light absorbing portion 334 makes with respect to the normal to the layer surface of the optical function layer 332 is 61 , θ 62 FIG. 23 is a further enlarged view of a portion of FIG. θ 61θ is the angle between an interface 334a, which is the upper side of the light absorbing portion 334 when the optical sheet 330 is in the position shown in FIG. 19, and the normal to the layer surface of the optical function layer 332. 62 is the angle between the interface 334b, which is the lower side of the light absorbing portion 334, of the interfaces between the light transmitting portion 333 and the light absorbing portion 334 in the same posture, and the normal to the layer surface of the optical function layer 332.

[0166] In this embodiment, θ 61 is preferably 0° or more and 10° or less. 61 is greater than 0° means that the angle is inclined downward from the light guide plate 21 side (light incident side, light incident-side light control layer 335) toward the liquid crystal panel 15 side (light output side, base layer 31 side). It is more preferably 4.0° or less, even more preferably 1.0° or less, and particularly preferably 0°. θ 61 If θ is less than 0°, manufacturing becomes difficult. 61 If θ is larger than 10°, the effect of controlling the direction of light by the optical function layer 332 in combination with the light-entering side light control layer 335 will be reduced. 61 If the angle is greater than 10°, the size of the light absorbing portions 334 in the arrangement direction (the width of the light absorbing portions, the size in the vertical direction on the paper surface of FIG. 23) becomes large, which tends to cause a problem of reduced light transmittance.

[0167] θ 62 is preferably 0° or more and 10° or less. 62 is greater than 0° means that the angle is inclined upward from the light guide plate 21 side (light incident side, light incident-side light control layer 335) toward the liquid crystal panel 15 side (light output side, base layer 31 side). It is more preferably 5.0° or less, and even more preferably 3.0° or less. This makes it possible to increase the amount of light directed upward while preventing a decrease in light transmittance. θ 62 If the angle is made larger than 10°, the size of the light absorbing portion 334 in the arrangement direction (the width of the light absorbing portion, the size in the vertical direction on the paper surface of FIG. 23) becomes large, which tends to cause a problem of a decrease in light transmittance, and may lead to a decrease in the amount of light traveling upward.

[0168] θ 61 , and θ 62 The relationship between the angle sizes is θ 61 <θ 62 This allows the viewing angle of the image light provided by the image source unit 310 to be wider on the upper side than on the lower side.

[0169] In addition, in the optical function layer 332, although not particularly limited, for example, the light transmitting portion 333 and the light absorbing portion 334 are formed as follows. c The pitch of the light transmitting portion 333 and the light absorbing portion 334 represented by D is preferably 20 μm or more and 100 μm or less, and more preferably 30 μm or more and 100 μm or less. c The thickness of the light absorbing portion 334 is preferably 50 μm or more and 150 μm or less, and more preferably 60 μm or more and 150 μm or less. By setting the thickness within these ranges, it is possible to achieve a more appropriate balance between light transmission and light absorption.

[0170] In this embodiment, an example has been shown in which the interface between the light transmitting portion 333 and the light absorbing portion 334 is linear in cross section, but the interface is not limited to this and may be polygonal, have a convex curved surface, a concave curved surface, etc. Furthermore, the cross-sectional shapes of the plurality of light transmitting portions 333 and light absorbing portions 334 may be the same, or may be different cross-sectional shapes with regularity.

[0171] Next, we will explain the light-entering side light control layer 335. The light-entering side light control layer 35 functions as a light control layer, and changes the direction of light entering the optical function layer 332 in advance, and the light-entering side light control layer 335 and the optical function layer 332 control the emission of light in a desired direction. In this embodiment, the light-entering-side light control layer 335 is configured to change the direction of light traveling in the normal direction of the optical sheet 330 so that the light is directed in a desired direction. More specifically, in this embodiment, in the positions shown in Figures 19 to 22, the light-entering-side light control layer 335 functions to change the direction of light traveling in the normal direction of the optical sheet 330 toward the observer so that the light is directed diagonally downward toward the observer. As a result, as will be described later, the light can be reflected at the upper interface 334a between the light-transmitting portion 333 and the light-absorbing portion 334, and directed diagonally upward.

[0172] Therefore, the light-entering side light control layer 335 is configured to include a support layer 335a and an optical element layer 335b. The support layer 335a is a transparent sheet-like member that functions as a support for the optical element layer 335b. The support layer 335a can be made of the same material as the base layer 31 and the light transmitting portion 333.

[0173] The optical element layer 335b is a layer that changes the direction of light entering the optical function layer 332, and is a layer in which a plurality of unit optical elements 335c are arranged on the surface of the support layer 335a opposite to the surface on which the optical function layer 332 is arranged. As described above, the unit optical elements 335c are configured to change the direction of light traveling in the normal direction to the optical sheet 330 so that the light is directed in one direction, and in this embodiment, in the positions shown in Figures 19 to 22, the unit optical elements 335c are configured to change the direction of light so that the light traveling in the normal direction to the optical sheet 330 is directed diagonally downward.

[0174] In this embodiment, the unit optical element 335c specifically has the following structure. Each unit optical element 335c is a triangular prism having a triangular cross section that protrudes to the side opposite the base layer 31 with the optical function layer 332 sandwiched therebetween, and is configured as a protrusion having the cross section and whose ridgeline extends in the same direction as the extension direction of the light transmitting portions 333 and the light absorbing portions 334 (bias angle α5=0°) or at an angle when viewed from the front of the optical sheet (bias angle α5≠0°). A plurality of unit optical elements 335c are arranged in a direction different from the extension direction.

[0175] When the ridgelines of the unit optical elements 335c are configured to extend at an angle relative to the extension direction of the light-transmitting portions 333 and the light-absorbing portions 334 in a front view of the optical sheet (bias angle α5 ≠ 0°), it is preferable that the extension direction of the light-transmitting portions 333 of the optical function layer 332 and the extension direction of the ridgelines of the unit optical elements 335c are relatively inclined at a bias angle α5 of greater than 0° and less than or equal to 45° in a front view of the optical sheet 330. This prevents moiré patterns caused by the arrangement of the light-transmitting portions 333 and the light-absorbing portions 334 and the arrangement of the unit optical elements 335c. Furthermore, if the angle α5 is greater than 45°, the efficiency of light direction control by the unit optical elements 335c decreases. A more preferable angle α5 is between 1° and 10°.

[0176] 23, the unit optical element 335c is configured to have a main refraction surface 335d and a rise surface 335e. The main refraction surface 335d and the rise surface 335e form two surfaces of a triangular prism, and the other surface overlaps the support layer 335a and is fixed to the support layer 335a.

[0177] 19 to 23, the main refraction surface 335d is a refraction surface that functions to change the direction of light traveling in the normal direction of the optical sheet 330 so that the light is directed obliquely downward. Therefore, the main refraction surface 335d is inclined so as to be close to the support layer 335a (optical functional layer 332) on the upper side in the vertical direction and away from the support layer 335a (optical functional layer 332) on the lower side in the vertical direction. As shown in FIG. 23, the angle θ 71 The inclination represented by θ has an angle with respect to the direction along the light incident surface 332b of the optical function layer 332. 71 Specifically, the angle is preferably greater than 0° and less than 17°, which makes it possible to more reliably control light to improve brightness in a desired direction.

[0178] The rise surface 335e is a surface required to form the main refraction surface 335d. However, as will be described later, light incident from the rise surface 335e is refracted there, and travels through the optical function layer 332 at an angle that makes it easy for the light to be absorbed by the light absorbing portion 334. Therefore, the rise surface 335e also has the function of more reliably blocking light in a direction that is not desired to be emitted. θ 72 The inclination of the rise surface 335e, represented by θ, is preferably 90° or less with respect to the direction along the light incident surface 332b of the optical function layer 332. If this angle is 90° or more, manufacturing becomes difficult. 72 is preferably 73° or more. This allows the angle between the main refraction surface 335d and the rise surface 335e to be 90° or an angle close to this, and allows light that has entered the main refraction surface 335d from the normal direction of the main refraction surface 335d to travel in a direction close to parallel to the rise surface 335e, making it possible to prevent the light from being reflected by the rise surface 335e and becoming stray light.

[0179] Figure 22 shows P q The pitch of the unit optical elements 335c shown by is the pitch P c It is preferable that it is smaller than P c It is more preferable that the pitch is not an integer multiple, such as 2 / 3 or 2 / 5, of P. This makes it possible to prevent moire from occurring due to the light absorbing portions 334 and the unit optical elements 335c. q is 3 μm or more. q If it is smaller than this, there is a problem that the processing accuracy deteriorates. Also, in Figure 22, D q The protruding height of the unit optical elements 335c from the support layer 335a shown in is preferably 1 μm or more and 15 μm or less. If it is smaller than this, there is a problem that the processing accuracy deteriorates, and if it is larger than this, moire is likely to occur between the light absorbing parts 334 and the unit optical elements 335c.

[0180] In the above embodiment, multiple unit optical elements 335c are arranged continuously without any gaps, but this is not limited to this, and an embodiment may also be possible in which a gap is provided between adjacent unit optical elements 335c and the surface of the support layer 335a is exposed in this portion. Furthermore, the plurality of unit optical elements 335c do not necessarily have to have the same shape, and may be changed as appropriate.

[0181] The support layer 335a and the optical element layer 335b (unit optical elements 335c) of the light-entering side light control layer 335 can be made of the same materials as the base layer 31 and the light-transmitting section 33 described above.

[0182] Next, the operation of the image source unit 310 having the above configuration will be described with reference to examples of optical paths. Note that these optical path examples are conceptual examples for the purpose of explanation and do not strictly represent the degree of reflection or refraction.

[0183] First, as shown in Fig. 20, light emitted from the light source 25 enters the light guide plate 21 from a light entrance surface, which is a side surface (end surface) of the light guide plate 21. Fig. 20 shows, as an example, the light L incident from the light source 25 into the light guide plate 21. 201 , L 202 An example of a light path is shown.

[0184] As shown in FIG. 20, light L incident on the light guide plate 21 201 , L 202 is repeatedly totally reflected by the light-emitting side surface of the light guide plate 21 and the rear surface on the opposite side thereof due to the difference in refractive index with air, and travels in the light guide direction (downward in the plane of the paper in FIG. 20).

[0185] However, a rear optical element 23 is disposed on the rear surface of the light guide plate 21. Therefore, as shown in FIG. 201 , L 202 The light may be redirected by the rear optical element 23 and enter the light output surface and the rear surface at an angle of incidence less than the critical angle for total reflection. In this case, the light may exit the light guide plate 21 from the light output surface and the rear surface opposite thereto.

[0186] Light L emitted from the light output surface201 , L 202 The light emitted from the rear surface of the light guide plate 21 is reflected by the reflective sheet 39 disposed on the rear surface of the light guide plate 21, enters the light guide plate 21 again, and travels through the light guide plate 21.

[0187] Light traveling within light guide plate 21 and light that is redirected by rear optical element 23 and reaches the light output surface at an incident angle less than the critical angle for total reflection are generated in each region along the light guide direction within light guide plate 21. As a result, light traveling within light guide plate 21 is gradually emitted from the light output surface. This makes it possible to uniformize the light amount distribution along the light guide direction of the light that is emitted from the light output surface of light guide plate 21.

[0188] The light emitted from light guide plate 21 then reaches light diffusion plate 26, where its uniformity is improved. The light is then diffused or concentrated as necessary by prism layer 27, and the light that has exited prism layer 27 reaches reflective polarizing plate 28. Here, light polarized in the direction along the transmission axis of reflective polarizing plate 28 passes through reflective polarizing plate 28 and travels toward optical sheet 330. On the other hand, light polarized in the direction along the reflection axis of reflective polarizer 28 is reflected as shown by the dotted arrow in Figure 20 and returned to the light guide plate 21 side. The returned light is reflected by light guide plate 21, rear optical element 23, or reflective sheet 39 and travels again toward reflective polarizer 28. The polarization direction of some of the light changes during this reflection, and some of this light is transmitted through reflective polarizer 28. The other light is returned again to the light guide plate side. In this way, the light reflected by reflective polarizer 28 can also be transmitted through reflective polarizer 28 by repeated reflection. This increases the utilization efficiency of light from light source 25. Here, the polarization direction of the light emitted from the reflective polarizer 28 is aligned with the transmission axis of the lower polarizer 14, and the light is in a polarized state that is transmitted through the lower polarizer 14.

[0189] The light emitted from the reflective polarizing plate 28 reaches the optical sheet 330. The light incident on the optical sheet 330 travels along the following optical path. An example of the optical path in the optical sheet 330 is shown in FIG. Light L shown in Figure 20 201 , light L 202 , and the light L shown in FIG. 241 , light L 242 The light incident on the main refraction surface 335d of the unit optical element 335c is refracted or transmitted through the main refraction surface 335d without being refracted depending on the angle of incidence on the main refraction surface 335d. (The light incident from the direction perpendicular to the inclined surface of the main refraction surface 335d is transmitted through the main refraction surface 335d without being refracted.) 242 )). As a result, most of the light becomes light directed diagonally downward toward the observer, and this light heads toward the interface 334a, which is the upper side of the light absorbing portion 334, of the interface between the light transmitting portion 333 and the light absorbing portion 334. Then, it is totally reflected at the interface 334a, and becomes light directed diagonally upward toward the observer, and the light is controlled to be directed in the desired direction. In particular, the inclination angle θ of the interface 334a 61 (See FIG. 23) is 0°, the light can be directed more upward. 61 By adjusting the angle, it is possible to direct the light upward to a desired range. At this time, if an interface 334b, which is the lower side of the light absorbing portion 334 among the interfaces between the light transmitting portion 333 and the light absorbing portion 334, is inclined so as to face obliquely upward toward the observer, the light L 201 , light L 202 , light L 241 , light L 242 The light absorbing portion 334 is less likely to obstruct the progression of such light, and more light can be guided in the desired direction.

[0190] Therefore, in the optical sheet 330, θ 71 The inclination angle of the main refracting surface 335c is expressed as θ 61 By combining this with the inclination angle of the interface 334a expressed as

[0047] , it is possible to easily guide light in a desired direction efficiently. Either one of them has a limit to the direction of light that can be guided, but by combining them, a synergistic effect is achieved, making it possible to more easily control the direction of light travel.

[0191] Also, the light L shown in FIG. 203 , L shown in Figure 24 243is incident on the rise surface 335e of the unit optical element 335c, and is refracted or transmitted through the rise surface 335e without being refracted depending on the angle of incidence on the rise surface 335e. Most of the light that has transmitted through the rise surface 335e in this way travels obliquely upward toward the observer and at an angle that transmits through the interface 334b ​​between the light-transmitting portion 333 and the light-absorbing portion 334 without being totally reflected at the interface. Therefore, the light is transmitted through the interface 334b ​​and absorbed by the light-absorbing portion 334. This makes it possible to efficiently absorb and block light emitted at a viewing angle equal to or greater than a desired angle, and furthermore to efficiently control the direction of travel of the light. Furthermore, since such light is likely to enter the liquid crystal panel and cause problems such as a decrease in contrast and color inversion, it is possible to absorb such light.

[0192] Light emitted from the optical sheet 330 is incident on the lower polarizer 14 of the liquid crystal panel 15. The lower polarizer 14 transmits one polarized component of the incident light and absorbs the other polarized component. The light that passes through the lower polarizer 14 is selectively transmitted through the upper polarizer 13 depending on the state of the electric field applied to each pixel. In this way, the liquid crystal panel 15 selectively transmits light from the surface light source device 320 pixel by pixel, allowing a viewer of the liquid crystal display device to view an image. At this time, the image light is provided to the viewer via the functional film 40, improving the quality of the image.

[0193] As described above, according to the optical sheet 330, refraction in the optical element layer 335b and total reflection at the interface 334a between the light-transmitting portion 333 and the light-absorbing portion 334 facilitates the upward emission of light incident on the optical sheet 330, while restricting downward emission. That is, for example, by using the optical sheet 330, it is possible to efficiently emit incident light in the upward direction toward the driver's viewpoint, thereby improving the brightness of the light emitted in the upward direction. On the other hand, since light that is emitted significantly upward is easily absorbed by the light-absorbing portion, it is possible to prevent reflection on the windshield. Therefore, by using the optical sheet of this embodiment in a liquid crystal display device, it is possible to control light more easily and improve visibility from the driver's viewpoint than when a conventional optical sheet is used.

[0194] This makes it easy to achieve light output characteristics such as those shown in Figure 25. Figure 25 is a graph with the vertical viewing angle on the horizontal axis and the relative luminance on the vertical axis. On the horizontal axis, positive (+) indicates an upward vertical direction and negative (-) indicates a downward vertical direction. As can be seen from FIG. 25, when viewed from a vertical viewing angle, the relative luminance peaks near +20° (vertically upward 20°) as can be seen from the position indicated by D in FIG. 25. In other words, the light is controlled so that the luminance peak is in the direction of the observer's viewpoint, which is different from the front (0°). Furthermore, as can be seen from the position indicated by E in FIG. 25, the relative luminance drops sharply near +50° (vertically upward 50°). In other words, it is possible to more reliably block light that travels significantly upward, which can cause reflections on the windshield of an automobile.

[0195] In the following, optical sheets and image source units were constructed for each of the above-mentioned configurations, and their performance was tested.

[0196] {Test Example A} In Example A, following the example of the image source unit 10, a test was carried out from the viewpoint of controlling the light output direction of the optical sheet.

[0197] [Configuration of optical sheet of test example A] <Test Example A1> In the test example A1, the θ 21 We created an optical sheet with a different θ 21 Other specific shapes of the optical sheets are as follows:

[0198] (base material layer) Material: Polycarbonate resin Thickness: 130μm

[0199] (optical functional layer) The pitch of the light-transmitting and light-absorbing parts (P in Figure 4) a ): 39 μm The width of the upper base of the light absorbing part (W in Figure 4) a ): 4 μm Width of the bottom of the light absorbing part (W in Figure 4) b ): 10μm The upper inclination angle of the light absorbing part (θ in Fig. 5) 11 ):3° The angle of inclination of the lower light absorbing part (θ in Fig. 5) 12 ):0° The thickness of the light absorbing part (D in Fig. 4) a ): 102μm Optical function layer thickness: 127μm Base thickness: 25μm Material and refractive index of light-transmitting part: UV-curable urethane acrylate resin with a refractive index of 1.56 Material and refractive index of the light absorbing part: UV-curable urethane acrylate resin with a refractive index of 1.49, containing 20% ​​by weight of acrylic beads with an average particle size of 4 μm containing carbon black. The inclination angle of the light-transmitting and light-absorbing parts relative to the pixel arrangement direction of the liquid crystal layer (bias angle α1): 5°

[0200] (Light control layer on the light output side) The angle of the rise surface (θ in Fig. 5) 22 ): 90° Pitch of unit optical elements (P in Figure 4) o ): 18μm Material of unit optical elements: UV-curable urethane acrylate resin with a refractive index of 1.50 Inclination angle relative to the bias angle α1 (bias angle α2): 3° Here, bias angle α2 is an angle that rotates in the same direction as bias angle α1 when the optical sheet is viewed from the front (the same applies to the following examples.) Therefore, in this example, the tilt angle of the extension direction of the unit optical elements with respect to the pixel arrangement direction of the liquid crystal layer is α1 + α2 = 8°. The angle of the main refractive surface (θ in Fig. 5) 21 ): 85° (Test Example A1-1), 80° (Test Example A1-2), 70° (Test Example A1-3), 60° (Test Example A1-4)

[0201] <Test Example A2> In the test example A2, the angle θ 31 The configuration other than the light-emitting side light control layer 135 was the same as that of Test Example A1. The angle of the rise surface was also fixed at 90°. The angle of the main refraction surface (θ in FIG. 9) was also changed. 31 ) are 85° (Test Example A2-1), 80° (Test Example A2-2), 70° (Test Example A2-3), and 60° (Test Example A2-4).

[0202] <Test Example A3> In Test Example A3, the angle of the rise surface (θ in FIG. 5) was 22 The angle of curvature (corresponding to the angle of curvature) was set to 80° (Test Example A3-1) and 100° (Test Example A3-2). Other than that, the test was the same as Test Example A2-2.

[0203] <Test Example A4> Test example A4 is an optical sheet having a configuration in which the output-side light control layer is removed from the optical sheet of test example A1, and other parts are the same as the optical sheet of test example A1.

[0204] [Evaluation method for Test Example A] Each of the optical sheets described above was modeled, and the relationship between the light output angle and the brightness at each light output angle was obtained through simulation. Light Tools (Synopsys) was used as the simulation software. The characteristics of the light source are shown in Figure 26. The horizontal axis of Figure 26 represents the viewing angle in the vertical direction (positive is upward, negative is downward), and the vertical axis represents the relative brightness, with the brightness at a viewing angle of 0° being 100%.

[0205] [Results of Test Example A] The results of Test Example A1 are shown in Figure 27, Test Example A2 in Figure 28, and Test Example A3 in Figure 29. In Figures 27 to 29, the graph of Test Example A4 is represented by A4. In FIG. 27, Test Example A1-1 is represented by A1-1, Test Example A1-2 by A1-2, Test Example A1-3 by A1-3, and Test Example A1-4 by A1-4. Similarly, in FIG. 28, Test Example A2-1 is represented as A2-1, Test Example A2-2 as A2-2, Test Example A2-3 as A2-3, and Test Example A2-4 as A2-4. In Figure 29, Test Example A3-1 is represented as A3-1, and Test Example A3-2 is represented as A3-2. Figure 29 also shows A2-2. In each graph, the horizontal axis represents the viewing angle in the vertical direction, with positive representing upward and negative representing downward, and the vertical axis represents the relative luminance when the light source characteristics shown in Figure 26 are taken as 100%.

[0206] As can be seen from these figures, the optical sheets according to test examples A1, A2, and A3 allowed the light output angle to be more precisely and efficiently controlled in a desired direction than the optical sheet according to test example A4.

[0207] When the light output angle is significantly shifted as in Test Examples A1-3, A1-4, A2-3, and A2-4, or when the angle of the rise surface is increased or decreased from 90° as in Test Examples A3-1 and A3-2, the relative luminance may increase when the light output angle is in the range of 60° to 90° on the positive or negative side. This is thought to be stray light from the rise surface. However, since much of this stray light can be absorbed by the polarizer, it is unlikely to cause any problems.

[0208] {Test Example B} In test example B, following the example of the image source unit 210, a test was conducted from the viewpoint of controlling the light output direction of the optical sheet.

[0209] [Configuration of light control member of test example B1] In Test Example B1, a light control member was produced following the example of light control member 229. The specific embodiment is as follows.

[0210] <First optical sheet> (base material layer) Material: Polycarbonate resin Thickness: 130μm

[0211] (optical functional layer) The pitch of the light-transmitting and light-absorbing parts (P in Figure 4) a ): 47μm The width of the upper base of the light absorbing part (W in Figure 4) a ): 3 μm Width of the bottom of the light absorbing part (W in Figure 4) b ): 22 μm The upper inclination angle of the light absorbing part (θ in Fig. 5) 11 ): 4.5° The angle of inclination of the lower light absorbing part (θ in Fig. 5) 12 ): 4.5° The thickness of the light absorbing part (D in Fig. 4) a ): 120μm Optical function layer thickness: 145μm Base thickness: 25μm Material and refractive index of light-transmitting part: UV-curable urethane acrylate resin with a refractive index of 1.56 Material and refractive index of the light absorbing part: UV-curable urethane acrylate resin with a refractive index of 1.49, containing 20% ​​by weight of acrylic beads with an average particle size of 4 μm containing carbon black.

[0212] (Light control layer on the light output side) The inclination angle of the main refractive surface (θ in Fig. 5) 21 ): 70° The inclination angle of the rise surface (θ in Fig. 5) 22 ): 90° Support layer thickness: 25μm Pitch of unit optical elements (P in Figure 4) o ): 26 μm Material of unit optical elements: UV-curable urethane acrylate resin with a refractive index of 1.50 Bias angle α3:5° of the direction in which the unit optical element extends relative to the direction in which the light transmitting part extends

[0213] <Second optical sheet> (base material layer) Material: Polycarbonate resin Thickness: 130μm

[0214] (optical functional layer) The pitch of the light transmitting and light absorbing parts (P in Figure 15) b ): 47μm Upper width of the light absorbing part (W in Figure 15) c ): 3 μm Width of the bottom of the light absorbing part (W in Figure 15) d ): 22 μm The angle of inclination of one side of the light absorbing part (θ in Figure 16) 41 ): 4.5° The inclination angle of the other side of the light absorbing part (θ 42 ): 4.5° The thickness of the light absorbing part (D in Figure 15) b ): 120μm Optical function layer thickness: 145μm Base thickness: 25μm Material and refractive index of light-transmitting part: UV-curable urethane acrylate resin with a refractive index of 1.56 Material and refractive index of the light absorbing part: UV-curable urethane acrylate resin with a refractive index of 1.49, containing 20% ​​by weight of acrylic beads with an average particle size of 4 μm containing carbon black.

[0215] (Light control layer on the light output side) Areas where unit optical elements are not arranged: 5.0 mm apart symmetrically around the center in the arrangement direction of the unit optical elements (W3 in Figures 14 and 15, 2.5 mm on each side). The inclination angle of the main refractive surface (θ in Figure 16) 51 ): The angle changes continuously from 90° at the center of the sheet (a portion where there are essentially no unit optical elements) to 68° at the edge of the sheet (the size of the second optical sheet in the direction in which the unit optical elements are arranged (W4 in Figure 15) is 300 mm). The inclination angle of the rise surface (θ in Figure 16) 52 ): 90° Support layer thickness: 25μm Pitch of unit optical elements (P in Figure 15) p ): 26 μm Material of unit optical elements: UV-curable urethane acrylate resin with a refractive index of 1.50 The bias angle α of the extension direction of the unit optical element relative to the extension direction of the light transmitting part is 4:5°

[0216] <Light control components> The first optical sheet was arranged so that the direction in which the light-transmitting portions extended was horizontal, and a second optical sheet was arranged on top of the first optical sheet so that it was on the light-emitting side, to form a light control member. At this time, the direction in which the light-transmitting portions of the second optical sheet extended was vertical (see FIG. 12).

[0217] [Configuration of light control member of test example B2] In Test Example B2, a light control member was used in which the light control layer on the light output side of the first optical sheet and the light control layer on the light output side of the second optical sheet were omitted from the light control member of Test Example B1.

[0218] [Evaluation method for Test Example B] The light control member of Test Example B was modeled, and the relationship between the luminance and each light output angle in the vertical and horizontal directions was obtained by simulation. Light Tools (Synopsys) was used as the simulation software. The characteristics of the light source are shown in Figure 30. The horizontal axis in Figure 30 represents the light output angle in the vertical and horizontal directions, and the vertical axis represents the relative brightness, with the brightness at a light output angle of 0° being taken as 100%.

[0219] [Results of Test Example B] Figure 31 shows the evaluation results for the light control member of Test Example B1. The horizontal axis of Figure 31(a) shows the light output angle in the vertical direction, and the vertical axis shows the relative luminance to 100% in Figure 30. The horizontal axis of Figure 31(b) shows the light output angle in the horizontal direction, and the vertical axis shows the relative luminance to 100% in Figure 30. Figure 32 shows the evaluation results for the light control member of Test Example B2. The horizontal axis of Figure 32(a) shows the light output angle in the vertical direction, and the vertical axis shows the relative luminance to 100% in Figure 30. The horizontal axis of Figure 32(b) shows the light output angle in the horizontal direction, and the vertical axis shows the relative luminance to 100% in Figure 30.

[0220] As can be seen from a comparison between FIG. 31(a) and FIG. 32(a), the provision of an optical element layer such as the first optical sheet made it possible to control and shift the light output angle. Furthermore, as can be seen from a comparison between Figure 31(b) and Figure 32(b), by providing an optical element layer such as a second optical sheet, it was possible to control the light emission angle in the horizontal direction, as explained in Figure 18(b).

[0221] {Test Example C} In test example C, following the examples of image source unit 10 and image source unit 210, in addition to controlling the light output direction, a test was conducted from the viewpoint of preventing the occurrence of moire by using a rough surface.

[0222] [Configuration of optical sheet of test example C] <Test Example C1> In the test example C1, the θ 21 The specific configurations of the other portions were as follows:

[0223] (base material layer) Material: Polycarbonate resin Thickness: 130μm

[0224] (optical functional layer) The pitch of the light-transmitting and light-absorbing parts (P in Figure 4) a ): 39 μm The width of the upper base of the light absorbing part (W in Figure 4) a ): 4 μm Width of the bottom of the light absorbing part (W in Figure 4) b ): 10μm The upper inclination angle of the light absorbing part (θ in Fig. 5) 11 ):3° The angle of inclination of the lower light absorbing part (θ in Fig. 5) 12 ):0° The thickness of the light absorbing part (D in Fig. 4) a ): 102μm Optical function layer thickness: 127μm Base thickness: 25μm Material and refractive index of light-transmitting part: UV-curable urethane acrylate resin with a refractive index of 1.56 Material and refractive index of the light absorbing part: UV-curable urethane acrylate resin with a refractive index of 1.49, containing 20% ​​by weight of acrylic beads with an average particle size of 4 μm containing carbon black. The tilt angle (bias angle α1) of the light-transmitting and light-absorbing parts relative to the pixel arrangement direction of the liquid crystal layer: 0°

[0225] (Light control layer on the light output side) The angle of the rise surface (θ in Fig. 5) 22 ): 90° Pitch of unit optical elements (P in Figure 4) o ): 18μm Material of unit optical elements: UV-curable urethane acrylate resin with a refractive index of 1.50 Inclination angle relative to the bias angle α1 (bias angle α2): 4° The angle of the main refractive surface (θ in Fig. 5) 21 4 types): 85°, 80°, 70°, 60° Forming rough surfaces on the main refraction surface and rise surface (2 types): Formed using a molding die blasted with glass having an average particle size of 10 μm, and formed using a molding die blasted with alumina having an average particle size of 2 μm (see Figure 33)

[0226] Using the above blasted mold (see Figure 33), four types of θ 21 x 2 types of rough surface = 8 types in total” unit optical elements were molded, and optical sheets were produced for each.

[0227] <Test Example C2> In Test Example C2, an image source unit was produced that included an optical sheet similar to the example of the second optical sheet 230, instead of the optical sheet of Test Example C1. The specific configuration is as follows. (base material layer) Material: Polycarbonate resin Thickness: 130μm

[0228] (optical functional layer) The pitch of the light transmitting and light absorbing parts (P in Figure 15) b ): 47μm Upper width of the light absorbing part (W in Figure 15) c): 3 μm Width of the bottom of the light absorbing part (W in Figure 15) d ): 22 μm The angle of inclination of one side of the light absorbing part (θ in Figure 16) 41 ): 4.5° The inclination angle of the other side of the light absorbing part (θ 42 ): 4.5° The thickness of the light absorbing part (D in Figure 15) b ): 120μm Optical function layer thickness: 145μm Base thickness: 25μm Material and refractive index of light-transmitting part: UV-curable urethane acrylate resin with a refractive index of 1.56 Material and refractive index of the light absorbing part: UV-curable urethane acrylate resin with a refractive index of 1.49, containing 20% ​​by weight of acrylic beads with an average particle size of 4 μm containing carbon black. The tilt angle (bias angle α1) of the light-transmitting and light-absorbing parts relative to the pixel arrangement direction of the liquid crystal layer: 0°

[0229] (Light control layer on the light output side) Areas where unit optical elements are not arranged: 5.0 mm apart symmetrically around the center in the arrangement direction of the unit optical elements (W3 in Figures 14 and 15, 2.5 mm on each side). The inclination angle of the main refractive surface (θ in Figure 16) 51 ): The angle changes continuously from 90° at the center of the sheet (a portion where there are essentially no unit optical elements) to 68° at the edge of the sheet (the size of the second optical sheet in the direction in which the unit optical elements are arranged (W4 in Figure 15) is 300 mm). The inclination angle of the rise surface (θ in Figure 16) 52 ): 90° Support layer thickness: 25μm Pitch of unit optical elements (P in Figure 15) p ): 18μm Material of unit optical elements: UV-curable urethane acrylate resin with a refractive index of 1.50 Bias angle α4:4° between the direction in which the light-transmitting portion extends and the direction in which the unit optical element extends Forming rough surfaces on the refraction and rise surfaces (2 types): Forming using a molding die blasted with glass having an average particle size of 10 μm, and forming using a molding die blasted with alumina having an average particle size of 2 μm (see Figure 33)

[0230] Using the blast-treated mold, two types of unit optical elements with rough surfaces were molded, and optical sheets were produced for each.

[0231] <Test example C3> In Test Example C3, the optical sheet was configured in such a way that the rough surfaces were not formed on the main refraction surfaces and the rise surfaces, unlike the optical sheet in Test Example C1.

[0232] <Test Example C4> In Test Example C4, the optical sheet was configured such that the main refraction surface and the rise surface were not roughened, unlike the optical sheet in Test Example C2.

[0233] [Evaluation and results of test example C] Moiré was visually observed for the image source unit of test sample C. As a result, slight moiré was observed in test samples C3 and C4, which did not have a rough surface. On the other hand, no moiré was observed in test samples C1 and C2, which had a rough surface. The light output direction could be controlled appropriately in all cases.

[0234] {Test Example D} In test example D, following the example of image source unit 10, in addition to controlling the light output direction, the relationship between the arrangement pitch of the light-transmitting sections (light-absorbing sections) and the arrangement pitch of the unit optical elements was changed and tested from the perspective of moire generation.

[0235] In the configuration of the above-mentioned test example C1, the pitch of the unit optical elements (P in FIG. 4) o The conditions and results are shown in Table 1. In Table 1, P a is the pitch (μm) of the light transmitting (light absorbing) part, P o is the pitch (μm) of the unit optical element.

[0236] The inventor is P m Based on this, P is obtained as follows: mx We focused on... P m is calculated as follows: P m =|(a·P a ·b·P o ) / (a·P a -b·P o )|

[0237] where P a ≧P o where a and b are integers between 1 and 10. a , P o Combinations of pitches from 1x (1x) to 10x (10x) are considered, which allows evaluation of moire occurrence over a wide range considering integer multiple pitches. And a certain P a , P o P of all combinations of a and b changed for the combination of m The largest P m P mx In this example, P a is set to 39 μm, and P o This shows an example of the above change. This P mx In contrast, if moire was observed as a result, it was marked as "present," and if moire was not observed, it was marked as "absent."

[0238] [Table 1]

[0239] As can be seen from Table 1, P mx The pitch (P a , P o ) can be adjusted to prevent moire from occurring.

[0240] {Test Example E} In Test Example E, an optical sheet modeled after the optical sheet 330 shown in FIGS. 19 to 23 and a comparative optical sheet were fabricated and tested.

[0241] [Configuration of optical sheet of test example E] <Test Example E1> (base material layer) Material: Polycarbonate resin Thickness: 130μm

[0242] (optical functional layer) Pitch (P in Figure 22) c ): 39 μm Upper width of the light absorbing part (W in Figure 22) a ): 4 μm Width of the bottom of the light absorbing part (W in Figure 22) b ): 10μm The upper inclination angle of the light absorbing part (θ in Figure 23) 61 ):0° The angle of inclination of the lower light absorbing part (θ in Figure 23) 62 ):3° The thickness of the light absorbing part (D in Figure 22) c ): 102μm Optical function layer thickness: 127μm Material and refractive index of light-transmitting part: UV-curable urethane acrylate resin with a refractive index of 1.56 Material and refractive index of the light absorbing part: UV-curable urethane acrylate resin with a refractive index of 1.49, containing 20% ​​by weight of acrylic beads with an average particle size of 4 μm containing carbon black.

[0243] (Light-input side light control layer) Thickness of the support layer (thickness of the support layer 335a in FIG. 23): 130 μm Pitch of unit optical elements (P in Figure 22) q ): 30μm The inclination angle of the main refractive surface of the unit optical element (θ in Figure 23) 71 ): 5° The inclination angle of the rise surface (θ in Figure 23) 72 ): 90° Material: UV-curable urethane acrylate resin with a refractive index of 1.50

[0244] <Test Example E2> The inclination angle of the main refractive surface of the unit optical element (θ in FIG. 23) 71 ) was set to 10°, and the other configurations were the same as those of Test Example E1.

[0245] <Test Example E3> The inclination angle of the main refractive surface of the unit optical element (θ in FIG. 23) 71 ) was set to 20°, and the other configurations were the same as those of Test Example E1.

[0246] <Test Example E4> As shown in FIG. 34, the inclination of the main refractive surface of the unit optical element is configured to be inclined from bottom to top toward the light source side, and θ 81 The angle of the main refractive surface represented by is set to 5°. This is set to the inclination angle of the main refractive surface of the unit optical element being "-5°". Other than this, it is the same as Test Example E1.

[0247] <Test Example E5> The inclination angle of the main refractive surface of the unit optical element (θ in FIG. 23) 71 ) was set to 0°, that is, a configuration in which no optical element layer was formed, and the other conditions were the same as those of Test Example E1.

[0248] [Display device configuration] Using the optical sheet according to Test Example E, other components were arranged in accordance with the example shown in FIG. 19 to form a surface light source device.

[0249] [Evaluation method] <Measurement position> For each test example, the luminance was measured at the following three viewing angles, and expressed as a luminance ratio relative to the luminance of each type when the optical sheet was removed from the surface light source device of the example shown in Figure 19 and the light source was turned on, taking 100%. (1) The luminance ratio from the center of the screen to the normal direction of the screen (front luminance). (2) The luminance ratio at a viewing angle of 40° horizontally and 20° vertically from the center of the screen (the so-called driver's viewpoint). The driver's viewpoint refers to the viewpoint when viewing a display device such as a car navigation system from the driver's seat when the display device is placed between the driver's seat and the passenger seat of a car. (3) Luminance ratio (light that causes reflections) based on total luminance at viewing angles of 0° horizontally and 40° to 80° vertically (in 5° increments) from the center of the screen.

[0250] <Luminance measurement method> The luminance was measured using an automatic variable angle luminance meter (GP-500, Murakami Color Research Institute) to measure the luminance of transmitted light at each of the viewing angles (1) to (3) above.

[0251] [result] The luminance ratio at each viewing angle is shown in Table 2. Based on these results, a graph is shown in Figure 35. Figure 35(a) shows the result of (1), Figure 35(b) shows the result of (2), and Figure 35(c) shows the result of (3). Each figure shows the results of the main refractive surface inclination angle (θ in Figure 23). 71 The dotted line indicates the luminance ratio level at 0°.

[0252] [Table 2]

[0253] At the viewing angle (1), as shown by the straight arrow in Figure 35(a), it is preferable that the luminance ratio is higher than when the main refraction surface inclination angle is 0°. Higher means higher front luminance. At the viewing angle (2), as shown by the straight arrow in Figure 35(b), it is preferable that the luminance ratio is higher than when the main refraction surface inclination angle is 0°. A higher luminance ratio means that the luminance from the driver's viewpoint is higher. At the viewing angle (3), it is preferable that the luminance ratio is lower than when the inclination angle of the main refraction surface is 0°, as shown by the straight arrow in Fig. 35(c). This means that when a display device such as a car navigation system is placed between the driver's seat and the passenger seat of a car, reflection on the windshield can be suppressed.

[0254] From the above viewpoint, the preferable results of (1) to (3) are all satisfied between the two dashed lines. Specifically, the inclination angle of the main refractive surface of the unit optical element provided in the light-entering side light control layer (θ 71 ) is greater than 0° and smaller than 17°. This makes it easy to control light so as to achieve a good balance between a number of optical characteristics. [Explanation of symbols]

[0255] 10, 210, 310 video source unit 15 LCD panel 20, 220, 320 surface light source device 21 Light guide plate 25 light source 26 Light diffuser 27 Prismatic Layer 28 Reflective polarizer 30, 230, 330 optical sheet 31, 231 Base material layer 32, 232, 332 optical functional layer 33, 233, 333 Light transmission part 34, 234, 334 Light absorbing part 35, 135, 235 Light control layer on the light output side (light control layer) 35b, 135b, 235b, 335b optical element layer 35c, 135c, 235c, 335c unit optical element 35d, 135d, 235d, 335d Main refractive surface 35e, 135e, 235e, 335e Rise surface 335 Light-input side light control layer (light control layer)

Claims

1. A planar optical sheet formed by laminating a plurality of layers, an optical function layer that is one of the plurality of layers, and an optical element layer that is another of the plurality of layers, The optical functional layer is a plurality of light transmitting portions each having a trapezoidal cross section and extending in one direction, the light transmitting portions being arranged at intervals in a direction different from the one direction; and light absorbing portions being arranged between adjacent light transmitting portions; The optical element layer comprises: a plurality of unit optical elements each of which is a protrusion extending at an angle of 1° to 45° relative to the one direction when viewed from the front of the optical sheet and arranged in a direction different from the extending direction; The unit optical element has a triangular cross section having a main refractive surface and a rise surface, the principal refraction surface is a surface inclined at an angle of more than 45° and not more than 89° with respect to a normal direction of the light output surface of the optical function layer, and the rise surface is a surface inclined at an angle of 80° or more and 100° or less with respect to a layer surface of the optical function layer, The pitch between the light transmitting portion and the light absorbing portion is 20 μm or more and 100 μm or less, and The thickness of the light absorbing portion is 50 μm or more and 150 μm or less. Optical sheet.

2. A planar optical sheet formed by laminating a plurality of layers, an optical function layer that is one of the plurality of layers, and an optical element layer that is another of the plurality of layers, The optical functional layer is a plurality of light transmitting portions each having a trapezoidal cross section and extending in one direction, the light transmitting portions being arranged at intervals in a direction different from the one direction; and light absorbing portions being arranged between adjacent light transmitting portions; The optical element layer comprises: a plurality of unit optical elements each of which is a protrusion extending at an angle of 1° to 45° relative to the one direction when viewed from the front of the optical sheet and arranged in a direction different from the extending direction; The unit optical element has a triangular cross section having a main refractive surface and a rise surface, the principal refraction surface is inclined at an angle greater than 0° and smaller than 17° with respect to the layer surface of the optical function layer, and the rise surface is inclined at an angle greater than or equal to 80° and less than 100° with respect to the layer surface of the optical function layer, The pitch between the light transmitting portion and the light absorbing portion is 20 μm or more and 100 μm or less, and The thickness of the light absorbing portion is 50 μm or more and 150 μm or less. Optical sheet.

3. 3. The optical sheet according to claim 1, wherein the surface of each of the unit optical elements is roughened.

4. The optical sheet according to claim 1 , wherein the main refraction surface and the rise surface are rough surfaces.

5. The arrangement pitch of the light transmitting portions is P ａ (μm), the arrangement pitch of the unit optical elements is P ｏ (μm), a and b are integers of 1 or more and 10 or less, P ｍ =|(a・P ａ ・b・P ｏ ) / (a・P ａ -b・P ｏ )| As such, the P ａ , the P ｏ The P obtained from all combinations of a and b for ｍ The largest of these is P ｍｘ (μm), the P ｍｘ The optical sheet according to claim 1 , wherein the thickness is 10,000 (μm) or less.

6. 6. The optical sheet according to claim 1, wherein the protruding height of the unit optical elements is 1 [mu]m or more and 10 [mu]m or less.

7. 7. The optical sheet according to claim 1, wherein a gap is provided between adjacent unit optical elements.

8. Two or more optical sheets according to any one of claims 1 to 7 are arranged, a light control member arranged such that a direction in which the light transmitting portion of one of the optical sheets extends intersects a direction in which the light transmitting portion of the other of the optical sheets extends when viewed from the front of the optical sheets;

9. A surface light source device comprising: a light source; and the optical sheet according to claim 1, which is disposed closer to a viewer than the light source.

10. A surface light source device comprising: a light source; and the light control member according to claim 8, which is disposed closer to a viewer than the light source.

11. 11. An image source unit comprising: the surface light source device according to claim 9; and a liquid crystal panel disposed on the light-emitting side of the surface light source device.

12. The image source unit according to claim 11 , wherein the light transmitting portion, the light absorbing portion, and the unit optical elements extend in a horizontal direction and are arranged in a vertical direction.

13. A display device comprising the image source unit according to claim 11 or 12 housed in a housing.

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