Optical laminate and optical device

Abstract

This optical laminate comprises a first optical layer having a first main surface and a second main surface on the opposite side from the first main surface, a plurality of first internal low-refractive-index layers that are discretely arranged along a first direction and are inclined with respect to the first main surface, and a second optical layer that is arranged so as to sandwich the plurality of first internal low-refractive-index layers between the second optical layer and the first optical layer, each of the plurality of first internal low-refractive-index layers having a refractive index lower than the refractive index of the first optical layer and the refractive index of the second optical layer, and each of the plurality of first internal low-refractive-index layers directing a portion of light incident on each of the plurality of first internal low-refractive-index layers from the first optical layer toward the first-main-surface side through total internal reflection.

Description

Optical laminate and optical device

[0001] The present invention relates to an optical laminate and an optical device, and particularly relates to a sheet-shaped optical laminate and an optical device. Here, the term "sheet-shaped" is used to include plate-shaped or film-shaped, regardless of the rigidity (flexibility) and thickness of the sheet. Note that the sheet-shaped optical laminate and optical device may be used in various forms such as a roll form.

[0002] Optical laminates are used in various optical devices (for example, lighting devices and display devices). For example, Patent Document 1 discloses an optical laminate for a lighting device. The optical laminate of Patent Document 1 is sheet-shaped and has two main surfaces located on opposite sides of each other. This optical laminate receives light from a light source at an end portion, and emits a part of the received light from one main surface side.

[0003] Japanese Unexamined Patent Publication No. 2023-142896

[0004] An object of the present invention is to provide an optical laminate and an optical device capable of reducing unintended emission of stray light.

[0005] According to an embodiment of the present invention, the solution described in the following items is provided.

[0006] [Item 1] An optical laminate comprising: a first optical layer having a first main surface and a second main surface opposite to the first main surface; a plurality of first inner low-refractive-index layers discretely arranged along a first direction and inclined with respect to the first main surface; and a second optical layer arranged between the first optical layer so as to sandwich the plurality of first inner low-refractive-index layers, wherein each of the plurality of first inner low-refractive-index layers has a refractive index smaller than that of the first optical layer and the second optical layer, and each of the plurality of first inner low-refractive-index layers directs a part of light incident on the respective first inner low-refractive-index layer from the first optical layer toward the first main surface side by total internal reflection.

[0007] [Item 2] The optical laminate according to Item 1, wherein the second main surface of the first optical layer has a plurality of recesses discretely arranged along the first direction, each of the plurality of recesses has a first inclined surface and a second inclined surface opposite to the first inclined surface, each of the plurality of first internal low refractive index layers is arranged on the first inclined surface of one of the plurality of recesses, and the second optical layer fills the plurality of recesses so as to be in contact with the plurality of first internal low refractive index layers.

[0008] [Item 3] The optical laminate according to Item 2, further comprising a plurality of second internal low refractive index layers, each of which is disposed on the second inclined surface of one of the plurality of recesses.

[0009] [Item 4] The optical laminate according to item 2 or 3, wherein the second main surface of the first optical layer includes a flat portion between two adjacent recesses among the plurality of recesses.

[0010] [Item 5] The optical laminate according to any one of items 1 to 4, further comprising a third optical layer disposed on the first main surface side or the second main surface side of the first optical layer.

[0011] [Item 6] The optical laminate according to Item 5, wherein the third optical layer has a third principal surface on the side of the first optical layer, a fourth principal surface on the opposite side of the third principal surface, and a side surface connecting the third principal surface and the fourth principal surface, and at the end of the third optical layer, the third principal surface, the fourth principal surface, or the side surface receives light from a light source.

[0012] [Item 7] The optical laminate according to any one of items 1 to 6, wherein each of the plurality of first internal low refractive index layers is formed from a material including a solid.

[0013] [Item 8] The optical laminate according to Item 7, wherein each of the plurality of first internal low refractive index layers is formed from a porous material.

[0014] [Item 9] The optical laminate according to any one of items 1 to 8, wherein the refractive index of each of the plurality of first internal low refractive index layers is 1.0 or more and 1.35 or less, the inclination angle of each of the plurality of first internal low refractive index layers with respect to the first main surface is 20° or more and 60° or less, and the thickness of each of the plurality of first internal low refractive index layers is 0.5 μm or more and 3.0 μm or less.

[0015] [Item 10] An optical laminate according to any one of items 1 to 9, wherein when light is incident from the second main surface side and viewed from the first main surface side, the visible light transmittance is 60% or more and the haze value is less than 30%.

[0016] [Item 11] An optical apparatus comprising an optical laminate described in any one of items 1 to 10, a light source, and

[0017] According to embodiments of the present invention, optical laminates and optical devices are provided that can reduce the emission of unintended stray light.

[0018] This shows a schematic cross-sectional view of optical device 100A_L according to Embodiment 1 of the present invention. This shows a schematic cross-sectional view of optical device 100B_L according to Embodiment 2 of the present invention. This shows a schematic cross-sectional view of optical device 100C_L according to Embodiment 3 of the present invention. This shows a schematic cross-sectional view of a modified example of optical device 100A_L according to Embodiment 1 of the present invention. This is a schematic plan view of optical device 100A_L. This is a schematic cross-sectional view of a recess 64 that optical device 100A_L may have. This is a schematic plan view of the recess 64. This is a schematic plan view showing variations of the recess 64. This shows a schematic cross-sectional view of optical device 90_L as a comparative example. This shows the results of calculating the dependence of the emission intensity of irradiated light LRa on the emission angle in optical device 90_L. This shows the results of calculating the dependence of the emission intensity of stray light LRc on the emission angle in optical device 90_L. The results of calculating the relationship between the peak intensity I1 of the irradiated light LRa, the peak intensity I2 of the stray light, and their peak intensity ratio I2 / I1 in the optical device of the embodiment, and the refractive index of the internal low refractive index layers 20A and 20B are shown.

[0019] The optical laminates and optical devices according to embodiments of the present invention will be described below with reference to the drawings. The optical laminates and optical devices according to embodiments of the present invention are not limited to those exemplified below.

[0020] (Embodiment 1) First, with reference to Figure 1, an example of the configuration of an optical device according to Embodiment 1 of the present invention, which can reduce the emission of unintended stray light, will be described. Figure 1 shows a schematic cross-sectional view of the optical device 100A_L according to Embodiment 1 of the present invention. As shown in Figure 1, the optical device 100A_L is a sheet-shaped optical device having an emission surface (upper in Figure 1) from which the irradiation light LRa is emitted, and a back surface (lower in Figure 1) opposite to the emission surface. The irradiation light LRa is emitted in the Z direction in Figure 1.

[0021] The optical device 100A_L can be used, for example, as an illumination device (front light or back light) for a display device. Alternatively, if the configuration shown in Figure 1 is used as an illumination device, and the optical device 100A_L further includes a display element on the emission side of the illumination device, the optical device 100A_L can be used as a display device. When the illumination device is a front light, the display element is a reflective display. When the illumination device is a back light, the display element is a transmissive display.

[0022] The configuration of the optical device 100A_L is described in detail below.

[0023] As shown in Figure 1, the optical device 100A_L includes a light source LS and an optical laminate 100A that receives light emitted from the light source LS, propagates the light in the Y direction, and emits it in the Z direction. The optical laminate 100A includes a light-receiving section that receives light emitted from the light source LS, a light guide layer 10 having a main surface 10a on the emission side and a main surface 10b on the back side, and a direction-changing layer 60 disposed on the main surface 10a side of the light guide layer 10. The direction-changing layer 60 directs a portion of the light propagating through the light guide layer 10 towards the emission side and reduces the emission of unintended stray light other than the irradiated light LRa from the back side.

[0024] The light-receiving portion of the light guide layer 10 may be, for example, the side surface 10c of the light guide layer 10 on the side facing the light source LS. Alternatively, if an incoupling element is placed on the main surface 10a or main surface 10b of a protruding portion of the light guide layer 10 that extends from the direction conversion layer 60 in the -Y direction, the light-receiving portion of the light guide layer 10 may be the main surface 10a or main surface 10b of the protruding portion of the light guide layer 10. As an incoupling element, for example, those disclosed in International Publication No. 2022 / 030543 or International Publication No. 2022 / 030544 can be used. The contents of these international publications are incorporated herein by reference. In this way, at the end of the light guide layer 10, the main surface 10a, the main surface 10b, or the side surface 10c connecting the main surface 10a and the main surface 10b receives light from the light source LS.

[0025] The direction conversion layer 60 comprises a shaping film 62 having a main surface 62a on the exit side and a main surface 62b on the back side. The light guide layer 10 can be said to be located on the main surface 62b side of the shaping film 62. The main surface 62b of the shaping film 62 has a plurality of recesses 64 discretely arranged along the Y direction. Each of the plurality of recesses 64 has a first inclined surface ISa and a second inclined surface ISb opposite to the first inclined surface ISa. The main surface 62b of the shaping film 62 includes a flat portion between two adjacent recesses 64 among the plurality of recesses 64.

[0026] The direction conversion layer 60 further comprises a plurality of first internal low refractive index layers 20A discretely arranged along the Y direction and inclined with respect to the main surface 62a. Each of the plurality of first internal low refractive index layers 20A is located on a first inclined surface ISa of a corresponding one of the plurality of recesses 64. Therefore, the inclination angle of each of the plurality of first internal low refractive index layers 20A with respect to the main surface 62a is equal to the inclination angle of the first inclined surface ISa of a corresponding one of the plurality of recesses 64 with respect to the main surface 62a. The "inclination angle of the first inclined surface ISa with respect to the main surface 62a" means the angle made between the first inclined surface ISa and the main surface 62a when the main surface 62a is moved in the -Z direction to the bottom of the first inclined surface ISa (see Figure 6A). Each of the plurality of first internal low refractive index layers 20A is not located on the flat portion of the main surface 62b of the shaping film 62.

[0027] The direction conversion layer 60 further comprises a plurality of second internal low refractive index layers 20B discretely arranged along the Y direction and inclined with respect to the main surface 62a. Each of the plurality of second internal low refractive index layers 20B is located on the opposite side of the plurality of first internal low refractive index layers 20A that corresponds to it. Each of the plurality of second internal low refractive index layers 20B is connected to the plurality of first internal low refractive index layers 20A that corresponds to it. Each of the plurality of second internal low refractive index layers 20B is positioned on the second inclined surface ISb of the plurality of recesses 64 that corresponds to it. Therefore, the inclination angle of each of the plurality of second internal low refractive index layers 20B with respect to the main surface 62a is equal to the inclination angle of the second inclined surface ISb of the plurality of recesses 64 that corresponds to it with respect to the main surface 62a. The "angle of inclination of the second inclined surface ISb with respect to the main surface 62b" refers to the angle formed between the second inclined surface ISb and the main surface 62a when the main surface 62a is moved in the -Z direction to the bottom of the second inclined surface ISb (see Figure 6A). None of the multiple second internal low refractive index layers 20B are placed on the flat portion of the main surface 62b of the shaped film 62.

[0028] The direction-changing layer 60 further includes an adhesive layer 52 positioned between it and the shaping film 62, sandwiching a plurality of first internal low-refractive-index layers 20A and a plurality of second internal low-refractive-index layers 20B. The adhesive layer 52 fills a plurality of recesses 64 so as to be in contact with the plurality of first internal low-refractive-index layers 20A and a plurality of second internal low-refractive-index layers 20B. Of the plurality of recesses 64, the areas other than the plurality of first internal low-refractive-index layers 20A and a plurality of second internal low-refractive-index layers 20B are filled with the adhesive layer 52. It can also be said that the plurality of first internal low-refractive-index layers 20A and a plurality of second internal low-refractive-index layers 20B are embedded inside the direction-changing layer 60.

[0029] If the adhesive layer 52 is soft enough to deform easily relative to the recess 64, it can effectively fill the above-mentioned area of ​​the recess 64. In this regard, the storage modulus of the adhesive layer 52 is, for example, 1.0 × 10⁻⁶. ５ (Pa) or less, preferably 9.0 × 10 ４ It is less than or equal to Pa, and 8.5 × 10 ４ It may be less than or equal to Pa. The lower limit is not particularly limited, but for example, 5.0 × 10 ３Pa or higher or 1.0 × 10⁻⁶ ４ It can be greater than (Pa). This storage modulus is the value measured at a temperature of 25°.

[0030] Each of the multiple first internal low refractive index layers 20A has a refractive index smaller than that of the shaping film 62 and the adhesive layer 52. Similarly, each of the multiple second internal low refractive index layers 20B has a refractive index smaller than that of the shaping film 62 and the adhesive layer 52. Each of the multiple first internal low refractive index layers 20A and each of the multiple second internal low refractive index layers 20B may be an air layer, but if they are formed from a material containing a solid, they can be manufactured, for example, as follows: The low refractive index layer is placed over the entire main surface 62b of the shaping film 62, and then the portion other than the inclined surfaces ISa and ISb of the recess 64 is removed. Alternatively, the internal low refractive index layers 20A and 20B are placed from the beginning only on the inclined surfaces ISa and ISb of the recess 64 on the main surface 62b of the shaping film 62.

[0031] In the optical laminate 100A, each of the multiple first internal low refractive index layers 20A directs a portion of the light propagating through the light guide layer 10 (irradiation light LRa) toward the exit surface side by internal total internal reflection (TIR). A portion of the light is incident on each of the multiple first internal low refractive index layers 20A while satisfying the conditions for internal total internal reflection (TIR). Each of the multiple first internal low refractive index layers 20A further transmits another portion of the light propagating through the light guide layer 10 (guided light LRb) without significantly changing its direction of propagation. Another portion of the light is incident on each of the multiple first internal low refractive index layers 20A while not satisfying the conditions for internal total internal reflection (TIR). The reason why the direction of propagation of the other portion of the light does not change significantly is that the adhesive layer 52 fills the recess 64 so as to be in contact with the internal low refractive index layers 20A and 20B.

[0032] As will be described later (see Figure 7), in the configuration in which the recess 64 has an air region, the other portion of the light propagating through the light guide layer 10 is refracted at the interface between the air region of the recess 64 and the adhesive layer 52. Therefore, the recess 64 transmits the other portion of the light propagating through the light guide layer 10 with a significant change in its direction of propagation. As a result, the guided light LRb, after being incident on the main surface 10b of the light guide layer 10, is not totally reflected by the main surface 10b of the light guide layer 10 but is emitted from the back as stray light.

[0033] In contrast, in the optical laminate 100A, the waveguide light LRb that has passed through the first internal low refractive index layer 20A is incident on the main surface 10b of the light guide layer 10, and then totally reflected by the main surface 10b of the light guide layer 10 and returned to the light guide layer 10. As a result, in the optical laminate 100A, the emission of unintended stray light other than the irradiated light LRa from the back surface can be reduced.

[0034] From the viewpoint of effectively emitting the irradiated light LRa and effectively reducing the emission of stray light, the refractive index of each of the multiple first internal low refractive index layers 20A may be, for example, 1.0 to 1.35. The inclination angle of each of the multiple first internal low refractive index layers 20A with respect to the main surface 62a may be 20° to 60°. The thickness of each of the multiple first internal low refractive index layers 20A may be, for example, 0.5 μm to 3.0 μm. Each of the multiple second internal low refractive index layers 20B may have the same refractive index and thickness as one of the corresponding first internal low refractive index layers 20A.

[0035] In the direction conversion layer 60, the multiple first internal low refractive index layers 20A, which function as a light distribution control structure, are configured so that more than 80% of the light propagating through the light guide layer 10 is directed toward the exit surface. The proportion of light propagating through the light guide layer 10 that is directed toward the exit surface can be controlled, for example, by adjusting the cross-sectional shape, planar shape, size, arrangement density, and distribution of the first internal low refractive index layers 20A.

[0036] For each of the inclined surfaces ISa and ISb, the internal low refractive index layers 20A and 20B are arranged in a plurality of recesses 64, and when viewed from the direction normal to the main surface 62a of the shaping film 62, the ratio of the area of ​​the plurality of recesses 64 to the area of ​​the shaping film 62 (occupancy rate) is as follows. The occupancy rate is preferably 1% to 80%, the upper limit is more preferably 50% or less, even more preferably 45% or less, and to obtain high transmittance and / or low haze value, it is preferably 30% or less, even more preferably 10% or less, and even more preferably 5% or less. For example, when the occupancy rate of the recesses 64 is 50%, a haze value of 30% can be obtained. The occupancy rate of the recesses 64 may be uniform, or it may be made so that the occupancy rate increases with increasing distance so that the brightness does not decrease even when the distance from the light source LS increases. For mass production by the roll-to-roll method or the roll-to-sheet method, it is preferable that the occupancy rate of the recesses 64 is uniform.

[0037] The optical laminate 100A is designed such that the refractive indices of the light guide layer 10, adhesive layer 52, and shaping film 62 are approximately equal. Therefore, Fresnel reflection of the irradiated light LRa and the guided light LRb at the interfaces of these components can be suppressed.

[0038] When light is incident on the shaping film 62 from the main surface 62b side and viewed from the main surface 62a side of the shaping film 62, the optical laminate 100A may have characteristics such as a visible light transmittance of 60% or more and a haze value of less than 30%. Preferably, the visible light transmittance is 70% or more, and more preferably 80% or more. Preferably, the haze value is less than 10%, and more preferably 5% or less. Here, visible light is defined as light with a wavelength of 380 nm or more and 780 nm or less. The visible light transmittance and haze value can be measured, for example, using a haze meter (manufactured by Murakami Color Technology Laboratory: product name HM-150).

[0039] From the above, the optical layered body 100A and optical device 100A_L according to Embodiment 1 of the present invention can reduce unintended emission of stray light. The optical layered body 100A includes a light guide layer 10 and a direction conversion layer 60, but is not limited to this example. The direction conversion layer 60 may function as a light guide layer having an orientation control structure. In that case, the optical layered body 100A does not need to include the light guide layer 10.

[0040] As described above, when the optical device 100A_L is used as an illumination device, emission of stray light from the back surface can be reduced, so that stray light is reflected elsewhere and mixed into the irradiation light LRa as returning light is less likely to occur. As a result, it is possible to suppress the irradiation light LRa from having an unintended light distribution. Furthermore, if the illumination device is a front light for a display device, it becomes difficult for an observer to visually recognize stray light.

[0041] In addition, as described above, when the optical device 100A_L is used as a display device, it is possible to suppress the irradiation light LRa from having an unintended light distribution, so that an observer can accurately visually recognize information displayed on the display element. Furthermore, if the illumination device in the display device is a front light, it is difficult for the observer to visually recognize stray light, and thus the observer can accurately visually recognize information displayed on the display element.

[0042] In this specification, the shaped film 62 is also referred to as a "first optical layer", and the adhesive layer 52 is also referred to as a "second optical layer". The light guide layer 10 is also referred to as a "third optical layer". The main surface 62a of the shaped film 62 is also referred to as a "first main surface", and the opposite main surface 62b is also referred to as a "second main surface". When the light guide layer 10 is disposed on the main surface 62b side of the shaped film 62, the main surface 10a of the light guide layer 10 on the shaped film 62 side is also referred to as a "third main surface", and the opposite main surface 10b is also referred to as a "fourth main surface". The Y direction is also referred to as a "first direction".

[0043] Note that 3D printer technology may be used to manufacture the direction conversion layer 60 in which a plurality of first internal low-refractive-index layers 20A and a plurality of second internal low-refractive-index layers 20B are embedded. In this case, the first optical layer and the second optical layer described above may be formed from the same material.

[0044] (Embodiment 2) Next, with reference to FIG. 2, a description is given of a configuration example of an optical device according to Embodiment 2 of the present invention that can reduce unintended emission of stray light. FIG. 2 is a schematic cross-sectional view of an optical device 100B_L according to Embodiment 2 of the present invention. The optical device 100B_L shown in FIG. 2 includes a light source LS, and an optical layered body 100B having a light guide layer 10 and a direction conversion layer 61. The direction conversion layer 61 shown in FIG. 2 differs from the direction conversion layer 60 shown in FIG. 1 in the following two points.

[0045] The first point is that in the shaped film 62, each of the plurality of recessed portions 64 has a first inclined surface ISa that inclines more gently with respect to the main surface 62a, and a second inclined surface ISb that inclines more steeply with respect to the main surface 62b. However, the first inclined surface ISa may incline more steeply with respect to the main surface 62a as shown in FIG. 1, and the second inclined surface ISb may incline more gently with respect to the main surface 62a as shown in FIG. 1. The second point is that no corresponding one of the plurality of second internal low-refractive-index layers 20B is disposed on the second inclined surface ISb of each of the plurality of recessed portions 64. The adhesive layer 52 fills the plurality of recessed portions 64 so as to be in contact with the plurality of first internal low-refractive-index layers 20A. Among the plurality of recessed portions 64, regions other than the plurality of first internal low-refractive-index layers 20A are filled with the adhesive layer 52. It can also be said that the plurality of first internal low-refractive-index layers 20A are embedded inside the direction conversion layer 60. Each of the plurality of second internal low-refractive-index layers 20B hardly contributes to directing irradiation light LR toward the emission surface side. In addition, the presence or absence of the plurality of second internal low-refractive-index layers 20B does not greatly affect the traveling direction of guided light LRb. Therefore, it is not necessary to necessarily dispose the plurality of second internal low-refractive-index layers 20B.

[0046] In the optical layered body 100B, each of the plurality of first internal low-refractive-index layers 20A directs part of light propagating through the light guide layer 10 (irradiation light LRa) toward the emission surface side by total internal reflection. Each of the plurality of first internal low-refractive-index layers 20A further transmits another part of the light propagating through the light guide layer 10 (guided light LRb) without greatly changing the traveling direction of the light.

[0047] The optical laminate 100B is designed such that the refractive indices of the light guide layer 10, adhesive layer 52, and shaping film 62 are approximately equal. Therefore, Fresnel reflection of the irradiated light LRa and the guided light LRb at the interfaces of these components can be suppressed.

[0048] Based on the above, the optical laminate 100B and optical device 100B_L according to Embodiment 2 of the present invention can reduce unintended stray light emission, similar to the optical laminate 100A and optical device 100A_L according to Embodiment 1 of the present invention.

[0049] (Embodiment 3) Next, with reference to Figure 3, an example of the configuration of an optical device according to Embodiment 3 of the present invention, which can reduce the emission of unintended stray light, will be described. Figure 3 shows a schematic cross-sectional view of the optical device 100C_L according to Embodiment 3 of the present invention. The optical device 100C_L comprises a light source LS and an optical laminate 100C. The optical laminate 100C comprises, in order from the emission surface side, a light guide layer 10, an adhesive layer 54, a direction conversion layer 60, and a base layer 30. In the optical device 100C_L shown in Figure 3, unlike the optical device 100A_L shown in Figure 1, the direction conversion layer 60 is arranged on the main surface 10b side of the light guide layer 10 via the adhesive layer 54. The direction conversion layer 60 is further arranged on the base layer 30. More specifically, the shaping film 62 is arranged on the base layer 30 via the adhesive layer 52. It can be said that the light guide layer 10 is arranged on the main surface 62a side of the shaping film 62.

[0050] In the optical laminate 100C, each of the multiple first internal low refractive index layers 20A directs a portion of the light propagating through the light guide layer 10 (irradiation light LRa) toward the exit surface by internal total internal reflection. Each of the multiple first internal low refractive index layers 20A also transmits another portion of the light propagating through the light guide layer 10 (guided light LRb) without significantly changing its direction of propagation. Instead of the direction conversion layer 60 shown in Figure 3, the direction conversion layer 61 shown in Figure 2 may be used.

[0051] The optical laminate 100C is designed so that the refractive indices of the light guide layer 10, adhesive layers 52 and 54, shaping film 62, and substrate layer 30 are approximately equal. Therefore, Fresnel reflection of the irradiated light LRa and the guided light LRb at the interfaces of these components can be suppressed.

[0052] Based on the above, the optical laminate 100C and optical device 100C_L according to Embodiment 3 of the present invention can reduce unintended stray light emission, similar to the optical laminate 100A and optical device 100A_L according to Embodiment 1 of the present invention.

[0053] In this specification, when the light guide layer 10 is located on the main surface 62a side of the shaping film 62, the main surface 10b of the light guide layer 10 on the shaping film 62 side is also referred to as the "third main surface," and the main surface 10a on the opposite side is also referred to as the "fourth main surface."

[0054] (Modifications) The optical devices 100A_L to 100C_L according to Embodiments 1 to 3 of the present invention are not limited to the above examples and can be modified in various ways. Next, a modification of the optical device 100A_L according to Embodiment 1 of the present invention will be described with reference to Figure 4. The following modifications can also be applied to the optical devices 100B_L and 100C_L according to Embodiments 2 and 3 of the present invention.

[0055] Figure 4 shows a schematic cross-sectional view of a modified example of the optical device 100A_L according to Embodiment 1 of the present invention. The optical device 110A_L shown in Figure 4 comprises a light source LS and an optical laminate 110A. Unlike the optical laminate 100A shown in Figure 1, the optical laminate 110A shown in Figure 4 comprises a first hard coat layer 40A disposed on the main surface 62a of the shaping film 62 and a second hard coat layer 40B disposed on the main surface 10b of the light guide layer 10. The pencil hardness of the hard coat layers 40A and 40B may be, for example, H or higher. The hard coat layers 40A and 40B can improve the scratch resistance of the output surface and back surface of the optical device 110A_L. It is not necessary to provide both hard coat layers 40A and 40B; only one of them may be provided.

[0056] (Planar shape and arrangement of recesses 64) Next, with reference to Figure 5, an example of the planar shape and arrangement of recesses 64 in which the internal low refractive index layers 20A and 20B are arranged on the inclined surfaces ISa and ISb will be described. Figure 5 shows a schematic plan view of the optical device 100A_L.

[0057] As shown in Figure 5, the multiple recesses 64 are discretely arranged, for example, in the light-guiding direction (Y direction) and in a direction perpendicular to the light-guiding direction (X direction) of the light-guiding layer 10. The size of the recesses 64 (length L, width W: see Figures 6A and 6B) is preferably such that the length L is 10 μm or more and 500 μm or less, and the width W is preferably 1 μm or more and 100 μm or less. Furthermore, from the viewpoint of light extraction efficiency, the height H (see Figure 6A) is preferably 1 μm or more and 100 μm or less.

[0058] Here, an example is shown in which multiple recesses 64 are discretely arranged in the light-guiding direction (Y direction) and in a direction perpendicular to the light-guiding direction (X direction) of the light-guiding layer 10, but this is not the only example. Multiple recesses 64 can be discretely arranged in the light-guiding direction (Y direction) and in a direction intersecting the light-guiding direction of the light-guiding layer 10. The discrete arrangement of the recesses 64 can be appropriately set according to the shape of the light-guiding layer 10 and the desired light distribution. Although light propagates in various directions within the light-guiding layer 10, the Y direction is referred to as the light-guiding direction, and light having a component in the Y direction (non-zero) is said to be propagating in the Y direction. The same applies to other directions. That is, light propagating in the -Y direction includes all light having a component in the -Y direction (non-zero).

[0059] The multiple recesses 64 are arranged discretely, for example, in the light-guiding direction and in directions intersecting the light-guiding direction. The discrete arrangement of the multiple recesses 64 helps to reduce the area occupied by the recesses 64 and obtain high transmittance and / or low haze value. The discrete arrangement may or may not have periodicity (regularity) in at least one direction. However, from the viewpoint of mass production, it is preferable that the multiple recesses 64 are arranged uniformly. For example, in the example shown in Figure 5, multiple recesses 64 having substantially the same shape and a curved surface convex in the same direction are arranged discretely and periodically throughout the entire area of ​​the light-guiding layer 10 in the light-guiding direction (Y direction) and in a direction perpendicular to the light-guiding direction (X direction). In this case, the pitch Px is preferably, for example, 10 μm or more and 500 μm or less, and the pitch Py is preferably, for example, 10 μm or more and 500 μm or less. In the example shown in Figure 5, they are arranged with a 1 / 2 pitch offset in each of the Y and X directions.

[0060] As shown in Figure 5, when viewed from the direction normal to the first main surface of the light guide layer 10, the first inclined surface ISa forms a curved surface that is convex toward the light source LS. The optical laminate 100A included in the optical device 100A_L, more specifically the light source LS that emits light toward the light receiving portion of the light guide layer 10, may be, for example, an LED device. Multiple LED devices are arranged in the X direction along the light receiving portion of the light guide layer 10. Since the light emitted from each of the multiple LED devices spreads in the Y direction, the first internal low refractive index layer 20A arranged on the first inclined surface ISa acts uniformly on the light if the first inclined surface ISa has a curved surface that is convex toward the light source LS.

[0061] Next, the shape of the recess 64 will be described with reference to Figures 6A, 6B, and 6C. Figure 6A shows a schematic cross-sectional view of the recess 64, Figure 6B shows a schematic plan view of the recess 64, and Figure 6C shows schematic plan views illustrating variations of the recess 64.

[0062] As shown in Figure 6A, the cross-sectional shape of the recess 64 is, for example, triangular. The inclination angle θa of the first inclined surface ISa on the light source side (light incident side) (inclination angle of the first internal low refractive index layer 20A) is, for example, 10° or more and 70° or less. If the inclination angle θa is less than 10°, the light utilization efficiency by the first internal low refractive index layer 20A may be low, and if it exceeds 70°, processing may be difficult. Also, the inclination angle θb of the second inclined surface ISb on the opposite side of the first inclined surface ISa (inclination angle of the second internal low refractive index layer 20B) is, for example, 10° or more and 100° or less. If the inclination angle θb is less than 10°, the amount of light directed in an undesirable direction by the second internal low refractive index layer 20B may increase, and similarly, if it exceeds 100°, the amount of light directed in an undesirable direction may also increase. Furthermore, in order to increase the amount of irradiation light LRa emitted from the emission surface and decrease the amount of stray light emitted from the back surface, the inclination angle θa of the first inclined surface ISa (inclination angle of the first internal low refractive index layer 20A) is preferably, for example, 20° or more and 60° or less, and the inclination angle θb of the second inclined surface ISb (inclination angle of the second internal low refractive index layer 20B) is preferably, for example, 20° or more and 90° or less.

[0063] As shown in Figures 6B and 6C, in the planar shape of the recess 64 when viewed from the direction normal to the first main surface of the light guide layer 10, the length L of the recess 64 is preferably 10 μm or more and 500 μm or less, and the width W is preferably 1 μm or more and 100 μm or less. The length L is, for example, twice or more the width W. The height H (see Figure 6A) is preferably 1 μm or more and 100 μm or less. When forming a shaped film having a recess having the planar shape shown in Figure 6B, a recess having the planar shape shown in Figure 6C may be formed depending on the processing accuracy of the mold. Even in such cases, the planar shape of the internal space can be characterized by the length L and width W.

[0064] (Examples) The optical apparatus 100A_L of Embodiment 1 of the present invention will be described below with reference to examples and comparative examples. However, the present invention is not limited to these examples. The examples and comparative examples are the results of calculations performed by simulation.

[0065] [Optical apparatus of comparative example] The optical apparatus of comparative example 1 has a structure different from the optical apparatus 100A_L shown in Figure 1 in the following respects. Specifically, the recess 64 has an air region. The inclined surfaces ISa and ISb of the recess 64 do not have internal low refractive index layers 20A and 20B. The recess 64 is not filled with adhesive layer 52.

[0066] Referring to Figure 7, the configuration of the comparative optical device will be explained. Figure 7 shows a schematic cross-sectional view of the comparative optical device 90_L. The optical device 90_L comprises a light source LS and an optical laminate 90. The optical laminate 90 comprises a light guide layer 10 and a direction conversion layer 59. The direction conversion layer 59 shown in Figure 7 differs from the direction conversion layer 60 shown in Figure 1 in the following two respects. The first is that the internal low refractive index layers 20A and 20B are not arranged on the inclined surfaces ISa and ISb of the recess 64. The second is that the interior of the recess 64 is not filled with an adhesive layer 52. Thus, in the optical laminate 90, the recess 64 has an air region.

[0067] The recess 64, which has an air region, directs a portion of the light propagating through the light guide layer 10 (irradiation light LRa) toward the exit surface through internal total internal reflection. The recess 64, which has an air region, further transmits another portion of the light propagating through the light guide layer 10 (guided light LRb) with a significant change in its direction of propagation. As a result, after the guided light LRb is incident on the main surface 10b of the light guide layer 10, it is not totally reflected by the main surface 10b of the light guide layer 10 but is emitted from the back surface as stray light LRc.

[0068] Next, the light distribution characteristics of the irradiated light LRa and stray light LRc in the comparative optical device 90_L will be explained with reference to Figures 8A and 8B. Figure 8A shows the calculated dependence of the emission angle of the emission intensity of the irradiated light LRa in the optical device 90_L. Figure 8B shows the calculated dependence of the emission angle of the emission intensity of the stray light LRc in the optical device 90_L. The emission angle has a positive value on the opposite side from the light source LS and a negative value on the same side as the light source LS, with reference to an axis perpendicular to the main surface 62a of the shaping film 62.

[0069] As shown in Figure 8A, the irradiated light LRa is mainly emitted from the emission surface in an angular range of -20° to 30°. The emission intensity of the irradiated light LRa has a peak at an emission angle of approximately 5°. As shown in Figure 8B, the stray light LRc is mainly emitted from the back surface in an angular range of 40° to 90°. The emission intensity of the stray light LRc has a peak at an emission angle of approximately 75°.

[0070] [Optical Apparatus of the Example] The optical apparatus of the example has substantially the same structure as the optical apparatus 100A_L shown in Figure 1. The same calculations as above were performed on the optical apparatus of the example. Figure 9 shows the results of calculating the relationship between the peak intensity I1 of the irradiated light LRa, the peak intensity I2 of the stray light, and their peak intensity ratio I2 / I1 in the optical apparatus of the example, and the refractive index of the internal low refractive index layers 20A and 20B. The black circles in Figure 9 represent the peak intensity I1 of the irradiated light LRa, the white circles in Figure 9 represent the peak intensity I2 of the stray light, and the white diamonds in Figure 9 represent the peak intensity ratio I2 / I1. In the upper left, as a reference (REF), the peak intensity I1 of the irradiated light LRa, the peak intensity I2 of the stray light, and their peak intensity ratio I2 / I1 in the optical apparatus 90_L shown in Figure 7 are shown. The value obtained by dividing the peak intensity I2 of the stray light by the peak intensity I1 of the irradiated light is also simply called the "peak intensity ratio I2 / I1".

[0071] As shown in Figure 9, in the comparative optical apparatus, the peak intensity I2 of stray light was higher than the peak intensity I1 of the irradiated light LRa. Therefore, the ratio of the peak intensities I2 / I1 was greater than 1.0.

[0072] In contrast, in the optical apparatus of the embodiment, when the refractive index of the internal low refractive index layers 20A and 20B was between 1.0 and 1.35, the peak intensity I2 of stray light was lower than the peak intensity I1 of the irradiated light LRa. Therefore, the ratio of the peak intensities I2 / I1 was less than 1.0. As the refractive index of the internal low refractive index layers 20A and 20B increased from 1.0 to 1.35, the peak intensity I1 of the irradiated light LRa decreased monotonically in a convex upward direction. The peak intensity I2 of stray light did not change significantly. When the refractive index of the internal low refractive index layers 20A and 20B was between 1.0 and 1.35, the ratio of the peak intensities I1 / I2 was 0.5 or less. When the refractive index of the internal low refractive index layers 20A and 20B was 1.4, the peak intensity I2 of stray light was lower than the peak intensity I1 of the irradiated light LRa, but the ratio of the peak intensities I1 / I2 exceeded 0.5 and became approximately 0.8. Therefore, when the refractive index of the internal low refractive index layers 20A and 20B is between 1.0 and 1.35, the irradiated light LRa can be effectively emitted, and the emission of stray light can be effectively reduced.

[0073] The above calculations were performed using the Lighttools software manufactured by Synopsys. Of the parameters set in the calculations, the parameters other than the thickness of the internal low refractive index layers 20A and 20B are as follows: For the light guide layer 10, the refractive index was 1.49 and the thickness was 2 mm. For the adhesive layer 52, the refractive index was 1.49 and the thickness was 0.02 mm. For the shaping film 62, the refractive index was 1.49 and the thickness was 0.02 mm. For the recess 64, the inclination angle of the first inclined surface ISa was 49°, the inclination angle of the second inclined surface ISb was 90°, the height H was 0.01 mm, the width W was 0.009 mm, the length L was 0.055 mm, the pitch Px in the X direction was 0.15 mm, and the pitch Py in the Y direction was 0.15 mm. The thickness of the internal low refractive index layers 20A and 20B was 0.002 mm.

[0074] (Other Examples) The optical apparatus 100B_L of Embodiment 2 of the present invention will be described below with reference to other examples and comparative examples. However, the present invention is not limited to the other examples. The other examples and comparative examples are the results of calculations performed by simulation, similar to the above examples and comparative examples.

[0075] [Optical Apparatus of Comparative Examples 1 to 4] The optical apparatuses of Comparative Examples 1 to 4 have a structure that differs from the optical apparatus 100B_L shown in Figure 2 in the following respects. Specifically, in the optical apparatuses of Comparative Examples 1 to 4, the recess 64 has an air region, similar to the example shown in Figure 7. The inclined surfaces ISa and ISb of the recess 64 do not have internal low refractive index layers 20A and 20B. The recess 64 is not filled with adhesive layer 52. In the optical apparatuses of Comparative Examples 1 to 4, the inclination angles of the first inclined surface ISa of the recess 64 are 49°, 40°, 30°, and 20°, respectively.

[0076] <Calculation Results> For the optical devices of Comparative Examples 1 to 4, the peak intensity I1 and peak intensity ratio I2 / I1 of the irradiated light LRa were calculated and the results are shown in Table 1.

[0077]

[0078] As shown in Table 1, the peak intensity ratio I2 / I1 was greater than 0.5 in the optical devices of Comparative Examples 1 to 4.

[0079] [Optical devices of Examples 1-6 and Comparative Example 5] The optical devices of Examples 1-6 and Comparative Example 5 have substantially the same structure as the optical device 100B_L shown in Figure 2.

[0080] In the optical apparatus of Examples 1 to 4, the inclination angles of the first inclined surface ISa of the recess 64 are 49°, 40°, 30°, and 20°, respectively. The refractive index of the internal low refractive index layers 20A and 20B is 1.2. The thickness of the internal low refractive index layers 20A and 20B is 1.0 μm.

[0081] In the optical apparatus of Example 5, the inclination angle of the first inclined surface ISa of the recess 64 is 49°. The refractive index of the internal low refractive index layers 20A and 20B is 1.3. The thickness of the internal low refractive index layers 20A and 20B is 1.0 μm.

[0082] In the optical apparatus of Example 6, the inclination angle of the first inclined surface ISa of the recess 64 is 49°. The refractive index of the internal low refractive index layers 20A and 20B is 1.2. The thickness of the internal low refractive index layers 20A and 20B is 3.0 μm.

[0083] In the optical apparatus of Comparative Example 5, the inclination angle of the first inclined surface ISa of the recess 64 is 49°. The refractive index of the internal low refractive index layers 20A and 20B is 1.4. The thickness of the internal low refractive index layers 20A and 20B is 1.0 μm.

[0084] As described above, the optical devices of Examples 1 to 6 satisfy all of the following conditions mentioned above for effectively emitting irradiated light LRa and effectively reducing stray light emission: The refractive index of each of the multiple first internal low refractive index layers 20A is 1.0 or more and 1.35 or less. The inclination angle of each of the multiple first internal low refractive index layers 20A with respect to the main surface 62a is 20° or more and 60° or less. The thickness of each of the multiple first internal low refractive index layers 20A is 0.5 μm or more and 3.0 μm or less. In contrast, the optical device of Comparative Example 5 does not satisfy the condition that the refractive index of each of the multiple first internal low refractive index layers 20A is 1.0 or more and 1.35 or less.

[0085] <Calculation Results 1> The results of calculating the peak intensity ratio of the irradiated light LRa and the peak intensity ratio I2 / I1 for the optical devices of Examples 1, 5, 6 and Comparative Example 5 are shown in Table 2. The peak intensity ratio of the irradiated light LRa for Examples 1, 5, 6 and Comparative Example 5 is the value obtained by dividing the peak intensity I1 of the irradiated light LRa for Examples 1, 5, 6 and Comparative Example 5 by the peak intensity I1 of the irradiated light LRa for Comparative Example 1. The inclination angle of the first inclined surface ISa is the same for the optical devices of Examples 1, 5, 6 and Comparative Example 5, as well as for Comparative Example 1.

[0086]

[0087] As shown in Table 2, in the optical apparatus of Comparative Example 5, the peak intensity ratio of the irradiated light LRa was less than 0.5. The peak intensity ratio I2 / I1 of the optical apparatus of Comparative Example 5 was approximately 0.6 compared to the peak intensity ratio I2 / I1 of the optical apparatus of Comparative Example 1. In the optical apparatus of Comparative Example 5, the intensity of the irradiated light LRa was significantly lower compared to the optical apparatus of Comparative Example 1.

[0088] In contrast, in the optical devices of Examples 1, 5, and 6, the peak intensity ratio of the irradiated light LRa was greater than 0.7. In particular, in the optical devices of Examples 1 and 6, the peak intensity ratio of the irradiated light LRa was greater than 0.9. The peak intensity ratio I2 / I1 of the optical devices of Examples 1, 5, and 6 was smaller than the peak intensity ratio I2 / I1 of the optical device of Comparative Example 1, and was 0.5 or less than that of the optical device of Comparative Example 1.

[0089] Therefore, in the optical devices of Examples 1, 5, and 6, the intensity of the irradiated light LRa did not decrease excessively compared to the optical device of Comparative Example 1. Furthermore, in the optical devices of Examples 1, 5, and 6, stray light emission was effectively reduced compared to the optical device of Comparative Example 1.

[0090] <Calculation Results 2> The results of calculating the peak intensity ratio of the irradiated light LRa and the peak intensity ratio I2 / I1 for the optical devices of Examples 2 to 4 are shown in Table 3. The peak intensity ratio of the irradiated light LRa for Examples 2 to 4 is the value obtained by dividing the peak intensity I1 of the irradiated light LRa of Examples 2 to 4 by the peak intensity I1 of the irradiated light LRa of the corresponding Comparative Examples 2 to 4. Here, "corresponding comparative example" means that the inclination angle of the first inclined surface ISa is the same as that of the example.

[0091]

[0092] As shown in Table 3, in the optical devices of Examples 2 to 4, the peak intensity ratio of the irradiated light LRa was greater than 0.9. The peak intensity ratio I2 / I1 of the optical devices of Examples 2 to 4 was smaller than the peak intensity ratio I2 / I1 of the optical devices of the corresponding Comparative Examples 2 and 3. In particular, the peak intensity ratio I2 / I1 of the optical devices of Examples 2 and 4 was 0.5 or less than the peak intensity ratio I2 / I1 of the optical devices of the corresponding Comparative Examples 2 and 4.

[0093] Therefore, in the optical devices of Examples 2 to 4, the intensity of the irradiated light LRa did not decrease as significantly compared to the optical devices of the corresponding Comparative Examples 2 to 4. Furthermore, in the optical devices of Examples 2 to 4, stray light emission was effectively reduced compared to the optical devices of the corresponding Comparative Examples 2 to 4.

[0094] Of the parameters set in the calculations in Tables 1 to 3, the parameters other than the inclination angle of the first inclined surface ISa of the recess 64, and the refractive index and thickness of the internal low refractive index layers 20A and 20B are as follows. The parameters described above were used for the light guide layer 10, adhesive layer 52, and shaping film 62.

[0095] (Preferred Examples of Each Component) Preferred examples of each component of the optical apparatus 100A_L to 100C_L according to Embodiments 1 to 3 of the present invention will be described.

[0096] The shaping film 62 can be manufactured, for example, as follows. A textured shaping film was manufactured according to the method described in Japanese Patent Publication No. 2013-524288. Specifically, the surface of a polymethyl methacrylate (PMMA) film was coated with lacquer (FineCure RM-64, manufactured by Sanyo Chemical Industries, Ltd.), an optical pattern was embossed onto the film surface containing the lacquer, and then the lacquer was cured to produce the desired textured shaping film. The total thickness of the textured shaping film is, for example, 130 μm.

[0097] The light guide layer 10 is formed from a known material with high transmittance to visible light. For example, the light guide layer 10 can be made from an acrylic resin such as polymethyl methacrylate (PMMA), a polycarbonate (PC) resin, a cycloolefin resin, or glass (e.g., quartz glass, alkali-free glass, borosilicate glass). The refractive index nGP of the light guide layer 10 is, for example, 1.40 or more and 1.80 or less. Unless otherwise specified, the refractive index refers to the refractive index measured with an ellipsometer at a wavelength of 550 nm. The thickness of the light guide layer 10 can be appropriately set depending on the application. For example, the thickness of the light guide layer 10 is 0.05 mm or more and 50 mm or less.

[0098] The thickness of the adhesive layers 52 and 54 is, independently of each other, for example, 0.1 μm to 100 μm, preferably 0.3 μm to 100 μm, and more preferably 0.5 μm to 50 μm. The refractive index of the adhesive layers 52 and 54 is, independently of each other, preferably 1.42 to 1.60, and more preferably 1.47 to 1.58. Furthermore, the refractive index of the adhesive layers 52 and 54 is preferably close to the refractive index of the light guide layer 10, shaping film 62, or base layer 30 with which it is in contact, and the absolute value of the difference in refractive index is preferably 0.2 or less.

[0099] The refractive indices nL1 of the internal low refractive index layers 20A and 20B are preferably, independently, for example, 1.30 or less, more preferably 1.20 or less, and even more preferably 1.15 or less. The internal low refractive index layers 20A and 20B are preferably formed from a material containing a solid, and the refractive index of the internal low refractive index layers 20A and 20B is preferably, for example, greater than 1.0 and 1.05 or more. The difference between the refractive index of the light guide layer 10 and the refractive index of the internal low refractive index layers 20A and 20B is preferably 0.20 or more, more preferably 0.23 or more, and even more preferably 0.25 or more. The internal low refractive index layers 20A and 20B with a refractive index of 1.30 or less can be formed from, for example, a porous material. The thickness of the internal low refractive index layers 20A and 20B are, independently, for example, 0.5 μm or more and 3.0 μm or less.

[0100] When the internal low refractive index layers 20A and 20B are formed from a porous material having internal voids, the porosity is preferably 35 volume% or more, more preferably 38 volume% or more, and particularly preferably 40 volume% or more. Within this range, internal low refractive index layers 20A and 20B with particularly low refractive indices can be formed. The upper limit of the porosity of the internal low refractive index layers 20A and 20B is, for example, 90 volume% or less, and preferably 75 volume% or less. Within this range, internal low refractive index layers 20A and 20B with excellent strength can be formed. The porosity is a value calculated from the refractive index value measured with an ellipsometer using the Lorentz-Lorentz formula.

[0101] For the internal low refractive index layers 20A and 20B, for example, a low refractive index layer having voids as disclosed in International Publication No. 2019 / 146628 can be used. All of the disclosures in International Publication No. 2019 / 146628 are incorporated herein by reference. Specifically, the low refractive index layer having voids includes substantially spherical particles such as silica particles, silica particles with micropores, silica hollow nanoparticles, fibrous particles such as cellulose nanofibers, alumina nanofibers, silica nanofibers, and plate-like particles such as nanoclay composed of bentonite. In one embodiment, the low refractive index layer having voids is a porous body in which particles (e.g., micropore particles) are directly chemically bonded to each other. In addition, at least a portion of the particles constituting the low refractive index layer having voids may be bonded to each other via a small amount (e.g., less than or equal to the mass of the particles) of a binder component. The porosity and refractive index of the internal low refractive index layers 20A and 20B can be adjusted by the particle size, particle size distribution, etc., of the particles constituting the internal low refractive index layers 20A and 20B.

[0102] Methods for obtaining internal low refractive index layers 20A and 20B having voids include, for example, the methods described in Japanese Patent Publication No. 2010-189212, Japanese Patent Publication No. 2008-040171, Japanese Patent Publication No. 2006-011175, International Publication No. 2004 / 113966, and their references. All disclosures of Japanese Patent Publication No. 2010-189212, Japanese Patent Publication No. 2008-040171, Japanese Patent Publication No. 2006-011175, and International Publication No. 2004 / 113966 are incorporated herein by reference.

[0103] As the internal low refractive index layers 20A and 20B having voids, silica porous material can be suitably used. Silica porous material can be manufactured, for example, by the following methods: a method of hydrolyzing and polycondensing at least one of a silicon compound; hydrolyzable silanes and / or silsesquioxanes, and their partial hydrolysates and dehydrated condensates; a method using porous particles and / or hollow fine particles; a method of generating an aerogel layer by utilizing the springback phenomenon; a method of using a pulverized gel obtained by pulverizing a gel-like silicon compound obtained by the sol-gel method and chemically bonding the resulting pulverized fine porous particles with a catalyst or the like. However, the low refractive index layer is not limited to silica porous material, and the manufacturing method is not limited to the manufacturing method exemplified; it can be manufactured by any manufacturing method. However, the porous layer is not limited to silica porous material, and the manufacturing method is not limited to the manufacturing method exemplified; it can be manufactured by any manufacturing method. Silsesquioxane is a silicon compound whose basic structural unit is (RSIO1.5, where R is a hydrocarbon group). While it is strictly different from silica, which has SiO2 as its basic structural unit, it shares a common feature with silica in that it has a network structure cross-linked by siloxane bonds. Therefore, in this context, porous materials containing silsesquioxane as a basic structural unit are also referred to as silica porous materials or silica-based porous materials.

[0104] A porous silica material may be composed of microporous particles of a gel-like silicon compound that are bonded together. Examples of microporous particles of a gel-like silicon compound include pulverized gel-like silicon compounds. A porous silica material can be formed, for example, by coating a substrate with a coating solution containing pulverized gel-like silicon compounds. The pulverized gel-like silicon compounds can be chemically bonded (e.g., siloxane bonds) by means of a catalyst, light irradiation, heating, etc.

[0105] The hardness of the hard coat layers 40A and 40B is preferably H or higher on the pencil hardness scale, more preferably 2H or higher, and even more preferably 4H or higher. On the other hand, there is no particular upper limit to the hardness of the hard coat layers 40A and 40B, but it is preferably 6H or lower on the pencil hardness scale, and more preferably 5H or lower. The pencil hardness is measured by a method in accordance with the "pencil hardness test" of JIS K 5400. The thickness of the hard coat layers 40A and 40B are, independently of each other, preferably 1 μm to 30 μm, more preferably 2 μm to 20 μm, and even more preferably 3 μm to 15 μm. If the thickness of the hard coat layers 40A and 40B is within this range, good scratch resistance is obtained.

[0106] The hard coat layers 40A and 40B can be composed of any suitable material, insofar as they satisfy the above-described properties. The hard coat layers 40A and 40B are, for example, cured layers of thermosetting resins or ionizing radiation (e.g., visible light, ultraviolet light) curable resins. Examples of such curable resins include acrylates such as urethane (meth)acrylate, polyester (meth)acrylate, and epoxy (meth)acrylate, silicon resins such as polysiloxane, unsaturated polyesters, and epoxy resins. The hard coat layers 40A and 40B can be formed, for example, by coating a material containing a solvent and a curable compound onto the surface of a target substrate and curing it. Details of hard coat layers suitably used as hard coat layers 40A and 40B are described, for example, in Japanese Patent Application Publication No. 2011-237789. All disclosures of Japanese Patent Application Publication No. 2011-237789 are incorporated herein by reference.

[0107] The optical laminates and optical devices according to embodiments of the present invention can reduce the emission of unintended stray light. The optical devices according to embodiments of the present invention can be used, for example, as illumination devices or display devices.

[0108] 10: Light guide layer, 10a, 10b: Main surface, 10c: Side surface, 20A: First internal low refractive index layer, 20B: Second internal low refractive index layer, 30: Substrate layer, 40A: First hard coat layer, 40B: Second hard coat layer, 52, 54: Adhesive layer, 59, 60, 61: Directional conversion layer, 62: Shaping film, 62a, 62b: Main surface, 64: Recess, 100A, 100B, 100C, 110A: Optical laminate, 100A_L, 100B_L, 100C_L, 110A_L: Optical device, ISa: First inclined surface, ISb: Second inclined surface, LRa: Irradiated light, LRb: Waveguided light, LRc: Stray light, LS: Light source

Claims

1. An optical laminate comprising: a first optical layer having a first main surface and a second main surface opposite to the first main surface; a plurality of first internal low refractive index layers discretely arranged along a first direction and inclined with respect to the first main surface; and a second optical layer disposed between the first optical layer and the plurality of first internal low refractive index layers, wherein each of the plurality of first internal low refractive index layers has a refractive index smaller than the refractive index of the first optical layer and the refractive index of the second optical layer, and each of the plurality of first internal low refractive index layers directs a portion of the light incident from the first optical layer to each of the plurality of first internal low refractive index layers toward the first main surface by internal total internal reflection.

2. The optical laminate according to claim 1, wherein the second main surface of the first optical layer has a plurality of recesses discretely arranged along the first direction, each of the plurality of recesses has a first inclined surface and a second inclined surface opposite to the first inclined surface, each of the plurality of first internal low refractive index layers is disposed on the first inclined surface of one of the plurality of recesses, and the second optical layer fills the plurality of recesses so as to be in contact with the plurality of first internal low refractive index layers.

3. The optical laminate according to claim 2, further comprising a plurality of second internal low refractive index layers, each of which is disposed on the second inclined surface of one of the plurality of recesses.

4. The optical laminate according to claim 2 or 3, wherein the second main surface of the first optical layer includes a flat portion between two adjacent recesses among the plurality of recesses.

5. The optical laminate according to claim 2 or 3, further comprising a third optical layer disposed on the first main surface side or the second main surface side of the first optical layer.

6. The optical laminate according to claim 5, wherein the third optical layer has a third principal surface on the side of the first optical layer, a fourth principal surface on the opposite side of the third principal surface, and a side surface connecting the third principal surface and the fourth principal surface, and at the end of the third optical layer, the third principal surface, the fourth principal surface, or the side surface receives light from a light source.

7. The optical laminate according to claim 2 or 3, wherein each of the plurality of first internal low refractive index layers is formed from a material including a solid.

8. The optical laminate according to claim 7, wherein each of the plurality of first internal low refractive index layers is formed from a porous material.

9. The optical laminate according to claim 2 or 3, wherein the refractive index of each of the plurality of first internal low refractive index layers is 1.0 or more and 1.35 or less, the inclination angle of each of the plurality of first internal low refractive index layers with respect to the first main surface is 20° or more and 60° or less, and the thickness of each of the plurality of first internal low refractive index layers is 0.5 μm or more and 3.0 μm or less.

10. The optical laminate according to claim 2 or 3, wherein when light is incident from the second main surface side and viewed from the first main surface side, the visible light transmittance is 60% or more and the haze value is less than 30%.

11. An optical device comprising an optical laminate according to claim 2 or 3, and a light source.

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