Light guide film and luminaire

Abstract

To provide a light guide film capable of improving incident efficiency of light from a light source.SOLUTION: A light guide film includes: a film which includes a first main surface, a second main surface arranged on the opposite side from the first main surface, and an end surface crossing each of the first main surface and the second main surface, and which guides light emitted from a light source including a light emitting surface and made to enter inside; and a light incident member which includes an upper surface, a lower surface arranged on the opposite side from the upper surface, and a light incident surface crossing the upper surface, which is arranged on the first main surface so that the lower surface opposes the first main surface, and which allows the light from the light source to enter inside the film. The thickness of the film is equal to or less than 1500 μm. The light source is arranged in such a manner that the light emitting surface at least opposes the light incident surface. An angle α formed by the upper surface of the light incident member arranged on the first main surface of the film and a normal line of the second main surface satisfies 60 degrees≤α≤120 degrees.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a light guiding film and a lighting device. [Background technology]

[0002] A method has been proposed for realizing lighting and displays with high design value or entertainment value by arranging light-guiding films on glass, windows, walls, floors, ceilings, etc.

[0003] For example, Patent Document 1 discloses a light guiding film having a light guiding layer having a light-receiving side surface that receives light emitted from a light source, and a light distribution control structure for light propagating within the light guiding layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 025067 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the light-guiding film of Patent Document 1, light from the light source is incident on the light-guiding layer only from the end face of the light-guiding layer, so if the light-guiding film is thin, the efficiency of light incidence into the light-guiding film may be low.

[0006] An object of the present invention is to provide a light guiding film capable of improving the incidence efficiency of light from a light source. [Means for solving the problem]

[0007] A light guiding film according to one embodiment of the present invention includes a film including a first main surface, a second main surface disposed opposite the first main surface, and end surfaces intersecting the first main surface and the second main surface, the film guiding light emitted from a light source including a light emitting surface and entering the film interior, the film including a top surface, a bottom surface disposed opposite the top surface, and a light entrance surface intersecting the top surface, the bottom surface being disposed on the first main surface such that it faces the first main surface, the light entrance member causing light from the light source to enter the film interior, the film having a thickness of 1500 μm or less, the light source being disposed such that the light emitting surface faces at least the light entrance surface, and an angle α between the top surface of the light entrance member disposed on the first main surface of the film and a normal to the second main surface satisfies 60 degrees≦α≦120 degrees. Effect of the Invention

[0008] According to the present invention, it is possible to provide a light guiding film capable of improving the incidence efficiency of light from a light source. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic plan view of a lighting device including a light guiding film according to an embodiment; [Diagram 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a schematic plan view of a light extraction layer included in the light guiding film according to the embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. [Diagram 5] 4 is a schematic cross-sectional view of a light extraction portion provided in a light extraction layer. FIG. [Figure 6] 1 is a schematic cross-sectional view of a lighting device illustrating an example of light guiding using a light guiding film according to Comparative Example 1. FIG. [Figure 7] 11 is a schematic cross-sectional view of a lighting device illustrating an example of light guiding using a light guiding film according to Comparative Example 2. FIG. [Figure 8] 1 is a schematic cross-sectional view of a lighting device illustrating an example of light guiding by a light guiding film according to an embodiment. [Figure 9] 11 is a schematic cross-sectional view of a lighting device including a light guiding film according to a first modified example. FIG. [Figure 10] 13 is a schematic cross-sectional view of an illumination device including a light guiding film according to a second modified example. FIG. [Figure 11] FIG. 13 is a schematic plan view of an illumination device including a light guiding film according to a third modified example. [Figure 12] FIG. 12 is a schematic cross-sectional view taken along line XII-XII in FIG. 11, showing an example of light guiding by a light guiding film according to a third modified example of an illumination device. [Figure 13] FIG. 1 is a diagram showing an apparatus for evaluating the efficiency of light incidence into a light guiding film. [Figure 14] FIG. 2 is a diagram showing a housing provided in an apparatus for evaluating the efficiency of light incidence on a light guiding film. [Figure 15] FIG. 13 illustrates a method for evaluating the luminance value of light extracted from a light guiding film. [Figure 16] 11 is a schematic cross-sectional view of a lighting device including a light guiding film according to Example 4. FIG. [Figure 17] 13 is a schematic cross-sectional view of a lighting device including a light guiding film according to Example 6. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In each drawing, the same components are given the same reference numerals, and duplicated explanations will be omitted as appropriate.

[0011] The following embodiments are illustrative of the light guiding film and the lighting device for embodying the technical idea of ​​the present invention, and the present invention is not limited to the following embodiments. The dimensions, materials, shapes, relative positions, etc. of the components described below are intended to be illustrative, and not to limit the scope of the present invention, unless otherwise specified. In addition, the sizes and positional relationships of the components shown in the drawings may be exaggerated for clarity.

[0012] In the drawings shown below, a Cartesian coordinate system having an X-axis, a Y-axis, and a Z-axis is used to represent directions. The X-axis, the Y-axis, and the Z-axis are approximately perpendicular to each other. The direction in which the arrow representing the X-axis points is expressed as the +X direction or +X side, and the direction opposite to the +X direction is expressed as the -X direction or -X side. The direction in which the arrow representing the Y-axis points is expressed as the +Y direction or +Y side, and the direction opposite to the +Y direction is expressed as the -Y direction or -Y side. The direction in which the arrow representing the Z-axis points is expressed as the +Z direction or +Z side, and the direction opposite to the +Z direction is expressed as the -Z direction or -Z side.

[0013] The Z direction along the Z axis refers to the direction along the normal to the second main surface of the light guiding film according to the embodiment. In this specification, "planar view" refers to viewing an object from the Z direction. The +Z direction is referred to as "up" and the -Z direction is referred to as "down." However, these directional expressions merely represent relative positional relationships for the purpose of explanation and do not limit the directions of the embodiment. In this specification, "thickness" refers to the length of an object in the Z direction.

[0014] [Embodiment] <Configuration example of lighting device including light guiding film according to embodiment> The configuration of an illumination device including a light guiding film according to an embodiment will be described with reference to Figs. 1 to 5. Fig. 1 is a schematic top view showing an example of an illumination device 100 including a light guiding film 10 according to an embodiment. Fig. 2 is a schematic cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a schematic plan view of a light extraction layer 150 included in the light guiding film 10. Fig. 4 is a schematic cross-sectional view taken along line IV-IV in Fig. 3. Fig. 5 is a schematic cross-sectional view of a light extraction portion 151 provided in the light extraction layer 150.

[0015] 1 and 2, the lighting device 100 includes a light source 50 including a light-emitting surface 51, and a light-guiding film 10. The light-guiding film 10 guides light that is emitted from the light-emitting surface 51 of the light source 50 and enters the light-guiding film 10.

[0016] 1 and 2, light guiding film 10 has film 1 including first main surface 11, second main surface 12 disposed on the opposite side of first main surface 11, and end surface 13 intersecting first main surface 11 and second main surface 12, and guides light incident therein. Light guiding film 10 also has light incident member 2 including upper surface 21, lower surface 22 disposed on the opposite side of upper surface 21, and light incident surface 23 intersecting upper surface 21, and disposed on first main surface 11 such that lower surface 22 faces first main surface 11, and causes light from light source 50 including light emitting surface 51 to enter film 1. From another perspective, light guiding film 10 is a film with a light incident member.

[0017] In this embodiment, the thickness of the film 1 is 1500 μm or less. The angle α between the upper surface 21 of the light incidence member 2 arranged on the first main surface 11 of the film 1 and the normal N1 of the second main surface 12 satisfies 60 degrees≦α≦120 degrees. In the example shown in FIG. 2, the light source 50 is arranged so that the light emitting surface 51 faces both the end surface 13 of the film 1 and the light incidence surface 23 of the light incidence member 2.

[0018] The lighting device 100 guides light incident from the light source 50 using the light guiding film 10 and emits the light in the +Z direction from almost the entire first main surface 11. The lighting device 100 is used, for example, with the light guiding film 10 disposed on an adherend such as glass, a window, a wall, a floor, or a ceiling. The lighting device 100 can illuminate an indoor space or the like with the light emitted from the first main surface 11.

[0019] Here, for example, when the light emitting surface of the light source and the end surface of the film are arranged opposite each other so that the light emitted from the light source is incident inside the film through the end surface of the film, if the thickness of the film is thin, there will be many parts of the light emitting surface of the light source that do not face the end surface of the film. In the parts of the light emitting surface that do not face the end surface of the film, the light emitted from the light emitting surface does not enter the inside of the film through the end surface of the film. As a result, the efficiency of light incidence into the film may be low.

[0020] The light guiding film 10 has a light incident member 2 disposed on the first main surface 11 of the film 1, and is disposed so that the light emitting surface 51 faces at least the light incident surface 23. In this configuration, even if the light emitting surface 51 has a portion that does not face the end surface 13 of the film 1, that portion faces the light incident surface 23. As a result, even if the light emitting surface 51 has a portion that does not face the end surface 13 of the film 1, the light from the light source 50 can be incident into the film 1 through the light incident surface 23.

[0021] On the other hand, as described later with reference to Figures 6 and 7, if the angle between the upper surface of the light incidence member arranged on the first main surface of the film and the normal line of the second main surface of the film is large, the light passing through the inside of the light incidence member and incident on the upper surface may not be totally reflected on the upper surface and may pass through the upper surface and leak out of the light incidence member, which may reduce the incidence efficiency of the light entering the inside of the film through the light incidence member.

[0022] 8, in the light guiding film 10, the angle α between the upper surface 21 of the light entrance member 2 disposed on the first main surface 11 of the film 1 and the normal N1 to the second main surface 12 satisfies 60 degrees≦α≦120 degrees, so that light that passes through the inside of the light entrance member 2 and is incident on the upper surface 21 can be totally reflected by the upper surface 21. This makes it possible to reduce the light that leaks to the outside of the light entrance member 2 through the upper surface 21 and improve the incidence efficiency of light that enters the inside of the film 1 via the light entrance member 2.

[0023] The angle α can be adjusted as appropriate to allow the light from the light source 50 to easily enter the film 1. For example, the lower limit of the angle α may be 70 degrees or more, more preferably 80 degrees or more, and the upper limit of the angle α may be 110 degrees or less, more preferably 100 degrees or less, and even more preferably 90 degrees or less.

[0024] In the light guiding film 10, the upper surface 21 of the light incident member 2 may be a flat surface. Having the upper surface 21 be a flat surface facilitates the manufacture of the light incident member 2, and therefore the manufacture of the light guiding film 10. However, the upper surface 21 is not limited to being a flat surface, and may include at least a part of a curved surface other than a flat surface as long as the angle α satisfies 60 degrees≦α≦120 degrees.

[0025] In the example shown in FIGS. 1 and 2, the light source 50 includes a plurality of LEDs (Light Emitting Diodes) arranged side by side in a direction in which the light incident surface 23 of the light incident member 2 extends (for example, the X direction). The light source 50 is arranged such that a light emitting surface 51 faces at least the light incident surface 23. The LEDs are mounted on the +Y side surface of the wiring board 60. The light emitting surface 51 of the light source 50 is composed of the light emitting surfaces of the plurality of LEDs. The light source 50 can emit light from each of the light emitting surfaces of the plurality of LEDs arranged side by side in the X direction in response to a driving current or driving voltage supplied via the wiring board 60.

[0026] 1 and 2, the light incidence member 2 is a rectangular parallelepiped whose longitudinal direction is the direction in which the light incidence surface 23 extends (for example, the X direction). The light incidence member 2 can be made of a resin material or a glass material having a transmittance of 60% or more for the light emitted from the light source 50. The resin material can be an acrylic resin, a polycarbonate resin, a cycloolefin polymer resin, an epoxy resin, or the like.

[0027] 1 and 2, length Fx represents the length of the film 1 in the direction in which the light incident surface 23 of the light incident member 2 extends (e.g., the X direction). Length Fy represents the length of the film 1 in the direction along the normal N2 of the light emitting surface 51 (e.g., the Y direction). The direction along the normal N2 of the light emitting surface 51 intersects with both the direction in which the light incident surface 23 of the light incident member 2 extends and the direction along the normal N1 of the second main surface 12. Length Bx represents the length of the light incident member 2 in the direction in which the light incident surface 23 of the light incident member 2 extends.

[0028] 2, length H represents the length of the light incident surface 23 in the direction along the normal N1 of the second main surface 12 (e.g., Z direction). From another perspective, length H is the distance between the upper surface 21 and the lower surface 22. Length W represents the length of the light emitting surface 51 of the light source 50 in the direction along the normal N1 of the second main surface 12. Length L represents the length of the light incident member 2 in the direction along the normal N2 of the light emitting surface 51 (e.g., Y direction).

[0029] 2, the film 1 includes a first transparent layer 110, a first adhesive layer 120, a second transparent layer 130, a second adhesive layer 140, and a light extraction layer 150. The first transparent layer 110, the first adhesive layer 120, the second transparent layer 130, the second adhesive layer 140, and the light extraction layer 150 are laminated in this order from top to bottom.

[0030] (First transmission layer 110 and second transmission layer 130) The first transmission layer 110 and the second transmission layer 130 may be made of a film having flat surfaces. The material used for the first transmission layer 110 and the second transmission layer 130 is preferably one having a low light absorption coefficient. For example, the material used for the first transmission layer 110 and the second transmission layer 130 may be an acrylic film such as PMMA (Poly Methyl Methacrylate), a cycloolefin film such as COP (Cyclo Olefin Polymer), a polyethylene film such as PET (Polyethylene Terephthalate), a polycarbonate film, or the like. The material used for the first transmission layer 110 and the material used for the second transmission layer 130 may be the same or different.

[0031] From the viewpoint of increasing the incidence efficiency of light from the light source 50, the thickness of each of the first transmission layer 110 and the second transmission layer 130 is preferably 30 μm or more, more preferably 40 μm or more, and even more preferably 60 μm or more or 100 μm or more. On the other hand, from the viewpoint of providing flexibility, the thickness of each of the first transmission layer 110 and the second transmission layer 130 light guide layers is preferably 800 μm or less, more preferably 600 μm or less, even more preferably 500 μm or less or less than 500 μm, and particularly preferably 400 μm or less, 300 μm or less, or 200 μm or less. The refractive index of the first transmission layer 110 and the second transmission layer 130 is preferably, for example, 1.45 or more and 1.60 or less.

[0032] (First adhesive layer 120 and second adhesive layer 140) The first adhesive layer 120 is disposed between the first transparent layer 110 and the second transparent layer 130, and bonds the first transparent layer 110 and the second transparent layer 130. The second adhesive layer 140 is disposed between the second transparent layer 130 and the light extraction layer 150, and bonds the second transparent layer 130 and the light extraction layer 150. The first adhesive layer 120 and the second adhesive layer 140 can transmit light incident from the light source 50.

[0033] At least one of an acrylic or polyester adhesive and a pressure sensitive adhesive may be used for each of the first adhesive layer 120 and the second adhesive layer 140. The material used for the first adhesive layer 120 and the material used for the second adhesive layer 140 may be the same as or different from each other. The refractive index of each of the first adhesive layer 120 and the second adhesive layer 140 is preferably approximately the same as the refractive index of the first transparent layer 110 and the second transparent layer 130, and is preferably, for example, 1.45 or more and 1.60 or less.

[0034] The ratio of each of the thicknesses of the first adhesive layer 120 and the second adhesive layer 140 to the total thickness of the film 1 can be 10% or more, and preferably 15% or more, and 20% or more. There is no particular upper limit, but it is, for example, 50% or less, 40% or less. By using such a first adhesive layer 120 and second adhesive layer 140, the film 1 can have suitable flexibility.

[0035] (Light extraction layer 150) The light extraction layer 150 includes a light extraction section 151 therein. The light extraction section 151 may be a plurality of internal spaces provided in the light extraction layer 150. Each of the plurality of internal spaces forms an interface that directs light to the +Z side by total internal reflection. The internal space may also be called a cavity. The internal space has a triangular cross-sectional shape with an apex angle on the +Z side, that is, a shape in a cross section perpendicular to the X direction and parallel to the YZ plane, and directs light L propagating in the film 1 to the +Y side to the +Z side. The light directed to the +Z side by the internal space is emitted from the film 1. In other words, the light guide film 10 can extract light from the first main surface 11 of the film 1 to the +Z side by the light extraction section 151 provided in the light extraction layer 150. "Extracting light" can also be called "taking out light". The cross-sectional shape of the internal space is not limited to a triangle, and may be a trapezoid or the like as long as it has an interface that directs light propagating in the +Y direction to the +Z side. By changing the cross-sectional shape of the internal space, for example the direction of the apex angle of a triangle, the direction in which light is emitted can be changed.

[0036] The light guiding film 10 can extract the light guided by the film 1 by the light extraction portion 151 and control the distribution of the extracted light, so that the visible light transmittance can be 60% or more and the haze value can be less than 10%. In addition, the light distribution, emission efficiency, and luminance distribution of the light emitted from the film 1 can be controlled by adjusting the shape and arrangement of the multiple internal spaces in the light extraction portion 151. The light extraction portion 151 is typically a void portion (air cavity) filled with air. However, the air cavity may be filled with a material having a refractive index lower than that of the light extraction layer 150 instead of air.

[0037] In the light extraction layer 150, a plurality of internal spaces that are light extraction sections 151 are arranged regularly or randomly along the second main surface 12, i.e., a plane that is approximately parallel to the XY plane. The size of each internal space can be appropriately selected within a range that can be installed inside the light extraction layer 150. For the light extraction layer 150 including the light extraction section 151 therein, for example, the light guide layers disclosed in WO 2019 / 182091, WO 2011 / 124765, WO 2019 / 087118, and WO 2011 / 127187 can be used. The entire disclosure of these publications is incorporated herein by reference.

[0038] The light extraction layer 150 is produced, for example, by laminating a first film having no pattern and a second film having a desired fine pattern thereon, or by bonding them with an adhesive (including a pressure-sensitive adhesive).

[0039] The second film may be micropatterned using laser patterning, direct laser imaging, laser drilling, masked or maskless laser or electron beam irradiation, or may be printed, inkjet printed, screen printed, etc. to impart individual properties and modify the material or refractive index value, or may be micro- or nano-dispensing, dosing, direct "writing", discrete laser sintering, micro-EDM (Electrical Discharge Machining), or micromachining, micromolding, imprinting, embossing, and the like.

[0040] From the viewpoint of obtaining a good visible light transmittance and haze value of the light guide film 10, the ratio (occupancy rate) of the area of ​​the plurality of internal spaces, which are the light extraction portion 151, to the area of ​​the light extraction layer 150 in a plan view is preferably 30% or less. The occupancy rate of the internal spaces may be uniform, or may increase with increasing distance from the light source 50 so that the brightness does not decrease even if the distance from the light source 50 increases. The occupancy rate of the internal spaces is preferably uniform. From the viewpoint of obtaining a good brightness, the occupancy rate of the internal spaces is preferably 1% or more and 30% or less, and the upper limit is more preferably 25% or less. In order to obtain a high visible light transmittance, the occupancy rate is preferably 10% or less, and more preferably 5% or less.

[0041] The above-described features of the light extraction unit 151 are not limited to the multiple internal spaces formed in the light extraction layer 150 exemplified here, but are common to various light distribution control structures. As a light distribution control structure constituted by multiple internal spaces, for example, a light distribution structure described in International Publication No. 2019 / 087118 can be used.

[0042] The light extraction portion 151 is not limited to a plurality of internal spaces, and may be a plurality of prisms arranged in the light extraction layer 150. The light extraction layer 150 may be a prism sheet including a plurality of prisms therein. A plurality of convex portions (prism portions) may be directly formed on the surface of the light extraction layer 150. The refractive index of the light extraction layer 150 is preferably approximately equal to the refractive index of the second adhesive layer 140, and the difference (absolute value) between the refractive indices is preferably 0.15 or less, and more preferably 0.1 or less.

[0043] A light distribution control structure in which light extraction section 151 is a plurality of internal spaces has a higher light utilization efficiency than a light distribution control structure such as a prism sheet. In addition, the light distribution can be controlled by adjusting the cross-sectional shape (for example, the angles θa and θb of the inclined surfaces in FIG. 5), size, arrangement density, distribution, and the like of the internal spaces. Meanwhile, the light guiding film 10 can control the visible light transmittance and haze value of the light guiding film 10 by adjusting the cross-sectional shape, size, arrangement density, and distribution of the plurality of internal spaces of light extraction section 151. The visible light transmittance of light guiding film 10 is 60% or more, preferably 65% ​​or more, 70% or more, 75% or more, or 80% or more. The haze value of light guiding film 10 is less than 10%, and can be preferably less than 9%, less than 8%, less than 7%, less than 6%, less than 5%, less than 4%, or less than 3%. The haze value can be measured using a haze meter.

[0044] The size and density of the internal space affect the haze value. The size of the internal space (length M, width r: see Figs. 3 to 5) is, for example, preferably 10.0 μm or more and 500.0 μm or less in length M, and preferably 1.0 μm or more and 100.0 μm or less in width r. From the viewpoint of the light extraction efficiency of the light extraction layer 150, the height q is preferably 1.0 μm or more and 100.0 μm or less. It is preferable that the multiple internal spaces are distributed discretely and uniformly, and for example, as shown in Fig. 3, it is preferable to arrange them periodically. In Fig. 3, the pitch Px is, for example, preferably 10.0 μm or more and 500.0 μm or less, and the pitch Py is, for example, preferably 10 μm or more and 500 μm or less. The interval E in Fig. 3 is the interval between the multiple internal spaces in the X direction. The interval D in Fig. 3 is the interval between the multiple internal spaces in the Y direction.

[0045] The configuration of each layer in the film 1 can be changed as appropriate. The film 1 may be configured with only the light extraction layer 150 as a configuration with the minimum number of layers. Furthermore, when the film 1 includes multiple layers, it does not necessarily have to include an adhesive layer for bonding the layers together, and the layers may be directly bonded together.

[0046] <Function of the light guide film 10> The function of light guiding film 10 will be described with reference to Figs. 6 to 8. Fig. 6 is a schematic cross-sectional view of lighting device 100X showing an example of light guiding by light guiding film 10X according to Comparative Example 1. Fig. 7 is a schematic cross-sectional view of lighting device 100Y showing an example of light guiding by light guiding film 10Y according to Comparative Example 2. Fig. 8 is a schematic cross-sectional view of lighting device 100 showing an example of light guiding by light guiding film 10 according to an embodiment. Figs. 6 to 8 show a cross section corresponding to line II-II in Fig. 1. For ease of understanding, in Comparative Example 1 and Comparative Example 2, the same reference numerals as those shown in Fig. 2 may be used for the same components as those of light guiding film 10 and lighting device 100 according to the embodiment.

[0047] In Comparative Example 1 shown in Fig. 6, light guiding film 10X differs from light guiding film 10 in that light entrance member 2X has upper surface 21X which is a curved surface. The curved surface is, for example, a free-form surface. Upper surface 21X which is a curved surface has a surface inclination which varies depending on the position, and includes a region where angle α between upper surface 21X and normal N1 is smaller than 60 degrees. Light LX1 and light LX2 represent light emitted from light-emitting surface 51 of light source 50 and guided inside light entrance member 2X and film 1, respectively.

[0048] The light LX1 emitted from the light-emitting surface 51 is incident on the light incidence member 2X through the light incidence surface 23. The light LX1 incident on the light incidence member 2X passes through the light incidence member 2X and reaches the upper surface 21X. The angle of incidence of the light LX1 on the upper surface 21X is greater than the critical angle. Therefore, the light LX1 incident on the upper surface 21X is totally reflected on the upper surface 21X. The light LX1 totally reflected on the upper surface 21X is incident on the film 1 through the lower surface 22X of the light incidence member 2X and the first main surface 11 of the film 1. The light LX1 incident on the film 1 is guided to the +Y side inside the film 1 while repeatedly being totally reflected on each of the first main surface 11 and the second main surface 12 of the film 1.

[0049] On the other hand, the light LX2 emitted from the light emitting surface 51 is incident on the inside of the light incident member 2X through the light incident surface 23. The light LX2 incident on the inside of the light incident member 2X is incident on the inside of the film 1 through the lower surface 22X of the light incident member 2X and the first main surface 11 of the film 1. The light LX2 incident on the inside of the film 1 is totally reflected on the second main surface 12 of the film 1, and then is incident on the inside of the light incident member 2X through the first main surface 11 of the film 1 and the lower surface 22X of the light incident member 2X, and reaches the upper surface 21X through the inside of the light incident member 2X. The incident angle of the light LX2 on the upper surface 21X is smaller than the critical angle. Therefore, the light LX2 incident on the upper surface 21X is not totally reflected on the upper surface 21X, and leaks out to the outside of the light incident member 2X through the upper surface 21X. The light LX2 leaking out to the outside of the light incident member 2X is not incident on the inside of the film 1. This causes light loss in the light guide film 10X. Thus, in the light guiding film 10X, the upper surface 21X is a curved surface including an area where the angle α is smaller than 60 degrees. As a result, some of the light passing through the inside of the light incident member 2X may not be totally reflected by the upper surface 21X and may leak out to the outside of the light incident member 2X through the upper surface 21X. As a result, the efficiency of light incidence into the film 1 decreases.

[0050] 7, the light guiding film 10Y differs from the light guiding film 10 in that it has a triangular prism-shaped light entrance member 2Y in which the light entrance surface 23 and the top surface 21Y are each inclined with respect to the normal line N1 of the second main surface 12. The top surface 21Y is a substantially flat surface whose angle α with the normal line N1 is smaller than 60 degrees. Light LY1 and light LY2 each represent light emitted from the light emitting surface 51 of the light source 50 and guided inside the light entrance member 2Y and the film 1, respectively.

[0051] The light LY1 emitted from the light emitting surface 51 is incident on the light incident member 2Y through the light incident surface 23. The light LY1 incident on the light incident member 2Y passes through the light incident member 2Y and reaches the upper surface 21Y. The incident angle of the light LY1 on the upper surface 21Y is greater than the critical angle. Therefore, the light LY1 incident on the upper surface 21Y is totally reflected on the upper surface 21Y. The light LY1 totally reflected on the upper surface 21Y is incident on the film 1 through the lower surface 22Y of the light incident member 2Y and the first main surface 11 of the film 1. The light LY1 incident on the film 1 is guided to the +Y side inside the film 1 while repeating total reflection on each of the first main surface 11 and the second main surface 12 of the film 1.

[0052] On the other hand, the light LY2 emitted from the light emitting surface 51 is incident on the inside of the light incident member 2 through the light incident surface 23. The light LY2 incident on the inside of the light incident member 2 is incident on the inside of the film 1 through the lower surface 22Y of the light incident member 2Y and the first main surface 11 of the film 1. The light LY2 incident on the inside of the film 1 is totally reflected on the second main surface 12 of the film 1, and then is incident on the inside of the light incident member 2Y through the first main surface 11 of the film 1 and the lower surface 22Y of the light incident member 2Y, and reaches the upper surface 21Y through the inside of the light incident member 2Y. The incident angle of the light LY2 on the upper surface 21Y is smaller than the critical angle. Therefore, the light LY2 incident on the upper surface 21Y is not totally reflected on the upper surface 21Y, and leaks out to the outside of the light incident member 2Y through the upper surface 21Y. The light LY2 leaking out to the outside of the light incident member 2Y is not incident on the inside of the film 1. This causes light loss in the light guide film 10Y. Thus, in the light guiding film 10Y, the upper surface 21Y is a substantially flat surface with the angle α being smaller than 60 degrees. As a result, some of the light passing through the inside of the light incident member 2Y may not be totally reflected by the upper surface 21Y and may pass through the upper surface 21Y and be emitted to the outside of the light incident member 2Y. As a result, the efficiency of light incidence into the film 1 decreases.

[0053] 8, the upper surface 21 is a substantially flat surface with an angle α satisfying 60 degrees≦α≦120 degrees. Light L1 and light L2 each represent light emitted from the light emitting surface 51 of the light source 50 and guided inside the light entrance member 2 and the film 1, respectively.

[0054] The light L1 emitted from the light-emitting surface 51 is incident on the light incidence surface 23 and enters the light incidence member 2. The light L1 that is incident on the light incidence member 2 passes through the light incidence member 2 and reaches the upper surface 21. The angle of incidence of the light L1 on the upper surface 21 is greater than the critical angle. Therefore, the light L1 that is incident on the upper surface 21 is totally reflected by the upper surface 21. The light L1 that is totally reflected by the upper surface 21 is incident on the film 1 through the lower surface 22 of the light incidence member 2 and the first main surface 11 of the film 1. The light L1 that is incident on the film 1 is guided to the +Y side inside the film 1 while being totally reflected by each of the first main surface 11 and the second main surface 12 of the film 1.

[0055] On the other hand, the light L2 emitted from the light emitting surface 51 is incident on the inside of the light incidence member 2 through the light incidence surface 23. The light L2 incident on the inside of the light incidence member 2 is incident on the inside of the film 1 through the lower surface 22 of the light incidence member 2 and the first main surface 11 of the film 1. The light L2 incident on the inside of the film 1 is totally reflected on the second main surface 12 of the film 1, and then is incident on the inside of the light incidence member 2 through the first main surface 11 of the film 1 and the lower surface 22 of the light incidence member 2, and reaches the upper surface 21 through the inside of the light incidence member 2. The incident angle of the light L2 on the upper surface 21 is larger than the critical angle. Therefore, the light L2 incident on the upper surface 21 is totally reflected on the upper surface 21, and is incident on the inside of the film 1 through the lower surface 22 of the light incidence member 2 and the first main surface 11 of the film 1. The light L2 incident on the inside of the film 1 is guided to the +Y side inside the film 1 while repeating total reflection on each of the first main surface 11 and the second main surface 12 of the film 1.

[0056] Thus, in light guiding film 10, upper surface 21 has angle α that satisfies 60 degrees≦α≦120 degrees. As a result, compared to Comparative Example 1 and Comparative Example 2, the amount of light that is not totally reflected at upper surface 21 of light entrance member 2 and leaks out of light entrance member 2 is reduced, and light guiding film 10 can improve the efficiency of light incidence into film 1.

[0057] [Variations] Modifications of the light guiding film according to the embodiment will be described below. Note that the same names and symbols as those in the already described embodiment indicate the same or similar members or components, and detailed descriptions will be omitted as appropriate. This also applies to the examples shown below.

[0058] <First Modification> A light guiding film according to a first modification will be described with reference to Fig. 9. Fig. 9 is a schematic cross-sectional view showing an illumination device 100a including a light guiding film 10 according to a first modification.

[0059] This modification differs from the above-described embodiment in that a reflecting member 3 is disposed on an opposing surface 24 located on the opposite side of the light incident surface 23 of the light incident member 2. In the example shown in Fig. 9, the reflecting member 3 reflects light L3 that is emitted from the light emitting surface 51 of the light source 50 and is incident on the opposing surface 24.

[0060] For example, if the opposing surface 24 is translucent to light from the light source 50, light L3 emitted from the light-emitting surface 51 and incident on the opposing surface 24 may pass through the opposing surface 24 and leak out from the light incident member 2 to the outside, thereby reducing the efficiency of light incidence on the film 1.

[0061] In the light guiding film 10, the reflecting member 3 is disposed on the facing surface 24, so that the light L3 incident on the facing surface 24 is reflected by the reflecting member 3. This allows the light L3 to enter the inside of the film 1 while being reflected by the light emitting surface 51, the second main surface 12, the top surface 21, etc., without leaking out from the light incident member 2 to the outside. As a result, in the light guiding film 10, the efficiency with which light enters the film 1 can be improved.

[0062] <Second Modification> A light guiding film according to a second modification will be described with reference to Fig. 10. Fig. 10 is a schematic cross-sectional view showing an illumination device 100b including a light guiding film 10 according to a second modification.

[0063] This modification differs from the above embodiment in that the light incident surface 23 is inclined so as to move away from the light source 50 with increasing distance from the first main surface 11.

[0064] Due to the configuration of the light guiding film 10, for example, light incident from the light source 50 to the light incident member 2 can more easily enter the film 1 compared to a case in which the top surface 21 is approximately parallel to the second main surface 12 and the light incident surface 23 and the light emitting surface 51 are each approximately perpendicular to the second main surface 12. This makes it possible to increase the efficiency with which light enters the film 1 in the light guiding film 10.

[0065] Furthermore, the upper surface 21 of the light incident member 2 can be inclined so as to approach the second main surface 12 the farther it is from the light source 50, the light incident surface 23 can be perpendicular to the upper surface 21 of the light incident member 2, and the light source 50 can be disposed so that the light emitting surface 51 is parallel to the light incident surface 23. This configuration also makes it easier for light incident from the light source 50 to the light incident member 2 to enter the film 1, and can increase the efficiency of light incidence to the film 1 in the light guiding film 10.

[0066] <Third Modification> An illumination device including a light guiding film according to a third modified example will be described with reference to Fig. 11 and Fig. 12. Fig. 11 is a schematic plan view showing an illumination device 100c including a light guiding film 10 according to a third modified example. Fig. 12 is a schematic cross-sectional view taken along line XII-XII in Fig. 11, showing an illumination device 100c illustrating an example of light guiding by the light guiding film 10.

[0067] In this modification, the light incident member 2 includes a convex portion 25 that protrudes downward from the lower surface 22 of the light incident member 2 and is disposed between the light source 50 and the end surface 13 of the film 1. In the example shown in Fig. 12, the convex portion 25 is disposed between the light emitting surface 51 of the light source 50 and the end surface 13 of the film 1. A portion of the light from the light source 50 passes through the convex portion 25 and is incident on the inside of the film 1. These points differ from the above-described embodiment.

[0068] 12, the convex portion 25 includes a convex portion lower surface 251 and a convex portion exit surface 252. The length of the convex portion 25 in the X direction is equal to the length of the light entrance member 2 in the X direction. The length of the convex portion 25 in the Z direction, i.e., the thickness, is approximately equal to the length of the film 1 in the Z direction, i.e., the thickness. Furthermore, the length T represents the length of the convex portion 25 in the direction along the normal line N2 of the light emitting surface 51 (Y direction). The length L represents the length of the light entrance member 2 in the direction along the normal line N2 of the light emitting surface 51, as described with reference to FIG. 2.

[0069] 12, when the convex portion 25 is disposed between the light-emitting surface 51 and the end surface 13, the convex portion lower surface 251 is located in approximately the same plane as the second main surface 12. The surface of the convex portion 25 facing the light-emitting surface 51, i.e., the surface on the -Y side of the convex portion 25, constitutes a part of the light incident surface 23. The convex portion exit surface 252 is the surface of the convex portion 25 located on the opposite side to the surface facing the light-emitting surface 51. The convex portion exit surface 252 is disposed so as to face the end surface 13 of the film 1.

[0070] 12 , almost all of the light emitted from the light source 50 passes through the light incident surface 23 and enters the inside of the light incident member 2. Of the light emitted from the light source 50, the light that passes through the light incident surface 23 and enters the inside of the convex portion 25 passes through the inside of the convex portion 25, and then passes through the convex portion exit surface 252 and the end surface 13 and enters the inside of the film 1.

[0071] For example, light L4 emitted from the light-emitting surface 51 is incident on the inside of the light incidence member 2 through the light incidence surface 23. The light L4 incident on the inside of the light incidence member 2 passes through the inside of the light incidence member 2 and reaches the upper surface 21. The angle of incidence of the light L4 on the upper surface 21 is greater than the critical angle. Therefore, the light L4 incident on the upper surface 21 is totally reflected on the upper surface 21. The light L4 totally reflected on the upper surface 21 is incident on the inside of the film 1 through the lower surface 22 of the light incidence member 2 and the first main surface 11 of the film 1. The light L4 incident on the inside of the film 1 is guided to the +Y side inside the film 1 while repeating total reflection on each of the first main surface 11 and the second main surface 12 of the film 1.

[0072] On the other hand, the light L5 emitted from the light emitting surface 51 is incident on the inside of the light incidence member 2 through the light incidence surface 23. The light L5 incident on the inside of the light incidence member 2 passes through the inside of the light incidence member 2 and reaches the convex lower surface 251. The incident angle of the light L5 on the convex lower surface 251 is greater than the critical angle. Therefore, the light L5 incident on the convex lower surface 251 is totally reflected on the convex lower surface 251. The light L5 totally reflected on the convex lower surface 251 passes through the inside of the light incidence member 2 and reaches the upper surface 21. The incident angle of the light L5 on the upper surface 21 is greater than the critical angle. Therefore, the light L5 incident on the upper surface 21 is totally reflected on the upper surface 21. The light L5 totally reflected on the upper surface 21 passes through the lower surface 22 of the light incidence member 2 and the first main surface 11 of the film 1 and is incident on the inside of the film 1. Light L5 incident on the inside of film 1 is guided inside film 1 to the +Y side while repeatedly undergoing total reflection at each of first main surface 11 and second main surface 12 of film 1.

[0073] As described above, in light guiding film 10 according to the third modification, light entrance member 2 includes convex portion 25, and almost all of the light emitted from light source 50 is incident on film 1 via light entrance member 2. This reduces the effect of light scattering due to roughness of the cut surface of the film end portion that occurs during film processing, and increases the efficiency of light incidence into film 1, compared to the case where part of the light emitted from light source 50 is incident on the inside of film 1 from end surface 13 of film 1.

[0074] [Examples and Comparative Examples] Examples and comparative examples will be described below, but the present invention is not limited to these examples.

[0075] <Evaluation method> (Common specifications of the light guiding film under evaluation) 1 and 2, the specifications of the light guide film common to the examples and comparative examples to be evaluated will be described. The length Fy of the film 1 was 250.0 mm, the length Fx of the film 1 was 100.0 mm, and the length Bx of the light entrance member 2 was 100.0 mm. The thickness of the film was 1500.0 μm or less. In addition, the light source 50 that inputs light to the light guide film was 24 LEDs of product number FB-120-NK made by FKK arranged in the X direction.

[0076] (Method of evaluating incidence efficiency) First, a method for evaluating the efficiency of incidence of light into a light guiding film will be described with reference to Fig. 13 and Fig. 14. Fig. 13 is a diagram showing an example of an apparatus E for evaluating the efficiency of incidence of light into a light guiding film. Fig. 14 is a diagram showing an example of a housing Mp in the apparatus E for evaluating the efficiency of incidence of light into a light guiding film. Note that Figs. 13 and 14 illustrate an example of evaluation of a light guiding film 10, but the apparatus E for evaluating incidence efficiency can evaluate light guiding films according to examples and comparative examples.

[0077] As the incident efficiency evaluation device E, an LED total luminous flux measurement system (HM-9165 manufactured by Otsuka Electronics Co., Ltd.) was used.

[0078] As shown in FIG. 13 and FIG. 14, the incidence efficiency evaluation device E includes a housing Mp, a driving unit Dr, an integrating hemisphere Ih, and a light measuring device Sr. The housing Mp has a mounting base M1 and a storage unit M2. The housing Mp mounts the driving unit Dr and the lighting device 100 including the light guide film 10 on the mounting base M1, and stores the driving unit Dr, the light source 50, the wiring board 60, the light incidence member 2, and a part of the film 1 inside the storage unit M2. The driving unit Dr moves the lighting device 100 in the Y direction to adjust the position of the lighting device 100 in the Y direction. The integrating hemisphere Ih collects light emitted from the lighting device 100 arranged on the mounting base M1, and spatially integrates it to make it uniform. The light measurement device Sr measures the amount of light emitted from the illumination device 100, which has been spatially integrated and homogenized by the integrating hemisphere Ih, and outputs the measurement result to an external device such as a PC (Personal Computer).

[0079] In Fig. 13, length Ey represents the length of the incidence efficiency evaluation device E in the Y direction. In Fig. 14, length My1 represents the length of the mounting table M1 in the Y direction. Length My2 represents the length of the accommodation section M2 in the Y direction. Thickness Mh1 represents the length from the lower surface of the mounting table M1 to the upper surface of the accommodation section M2. Thickness Mh2 represents the length from the upper surface of film 1 of the light guiding film 10 mounted on the mounting table M1 to the upper surface of the accommodation section M2.

[0080] In the evaluation of the incidence efficiency of light into the light guiding film using the incidence efficiency evaluation device E, the length Ey was 1650.0 mm, the length My1 was 350.0 mm, the length My2 was 70.0 mm, the thickness Mh1 was 35.0 mm, and the thickness Mh2 was 34.5 mm. The evaluation was performed with 200 mm of the length Fy of the film 1 exposed from the housing portion M2 of the housing Mp.

[0081] As a specific procedure for evaluating the incidence efficiency of light into a light guiding film using the incidence efficiency evaluation device E, first, the light guiding film was placed on the mounting table M1 so that the first main surface 11 of the film 1 faces the +Z direction, and the amount of light emitted from the first main surface 11 was measured. Next, the light guiding film was turned upside down, that is, the light guiding film was placed on the mounting table M1 so that the second main surface 12 of the film 1 faces the +Z direction, and the amount of light emitted from the second main surface 12 was measured. Here, in order to avoid the amount of light emitted from the end face on the +Y side of the film 1, i.e., the end face opposite to the end face 13, being measured redundantly during the measurement of the first main surface 11 and the measurement of the second main surface 12, the measurement of the amount of light emitted from the second main surface 12 was performed with the end face on the +Y side of the film 1 covered with black tape. The incidence efficiency of light into the light guiding film was calculated by the following formula. <Incoming efficiency> = <Amount of light emitted from film 1> / <Amount of light emitted from light source 50> Here, <amount of light emitted from film 1> is the sum of the amounts of light emitted from first main surface 11 of film 1, second main surface 12 of film 1, and the end face of film 1 on the +Y side.

[0082] (Luminance value evaluation method) Fig. 15 is a diagram showing an example of a method for evaluating the luminance value of light extracted from a light guiding film. Note that Fig. 15 illustrates an example of evaluating light guiding film 10, but the luminance value evaluation method can also be used to evaluate light guiding films according to examples and comparative examples.

[0083] 15, in evaluating the luminance value of light extracted from the light guiding film, the luminance value of light emitted from film 1 was measured by a two-dimensional light radiometer Lm placed approximately 500 mm above the top surface of film 1 in light guiding film 10. SR-5000-HS manufactured by TOPCON Corporation was used as the two-dimensional light radiometer Lm.

[0084] <Specifications and evaluation results of Examples and Comparative Examples> Table 1 shows the specifications and evaluation results of Examples 1 to 11 and Comparative Examples 1 and 2. Table 2 shows the evaluation indexes for determining the luminance value in Table 1.

[0085] [Table 1]

[0086] [Table 2]

[0087] (Specifications of Examples 1 to 3 and Example 5) Examples 1 to 3 and Example 5 in Table 1 are light-guiding films 10 according to the first modified example shown in FIG. 9, in which the length H of the light incident surface 23, the length W of the light-emitting surface 51 of the light source 50, and the length L of the light incident member 2 are different.

[0088] (Specifications of Example 4) Example 4 in Table 1 corresponds to the light guiding film 10 shown in FIG. 16. FIG. 16 is a schematic cross-sectional view showing an example of an illumination device including the light guiding film 10 according to Example 4. In Example 4 shown in FIG. 16, the length W of the light emitting surface 51 is 2.0 mm, while the length H of the film 1 is 0.5 mm, and the length H is shorter than the length W. In Example 4, light L6 emitted from a region of the light emitting surface 51 that does not face the light incident surface 23 is not incident on the light incident member 2 and is not incident on the film 1.

[0089] (Specifications of Example 6) Example 6 in Table 1 corresponds to the light guiding film 10 shown in FIG. 17. FIG. 17 is a schematic cross-sectional view showing an example of an illumination device including the light guiding film 10 according to Example 6. In Example 6 shown in FIG. 17, the length W of the light emitting surface 51 is 2.0 mm, while the length H of the film 1 is 5.0 mm, and the length H is longer than the length W. In Example 6, in the light that is emitted from the light emitting surface 51, passes through the light incident surface 23, and is then incident on the light incident member 2, and is totally reflected by the upper surface 21, some of the light leaks out of the light incident member 2 from the opposing surface 24, and is not incident on the film 1. Light L7 shown in FIG. 17 represents such light that is emitted from the opposing surface 24 and is not incident on the film 1.

[0090] (Specifications of Example 7) Example 7 in Table 1 corresponds to the light guiding film 10 according to the embodiment shown in FIGS.

[0091] (Specifications of Examples 8 to 10) Examples 8 to 10 in Table 1 are combinations of light guiding film 10 relating to the first variant and light guiding film 10 relating to the third variant, with the length H of light incident surface 23, the length W of light emitting surface 51 of light source 50, and the length L of light incident member 2 being different.

[0092] (Specifications of Example 11) Example 11 in Table 1 corresponds to the light guiding film 10 according to the third modified example shown in FIGS.

[0093] (Specifications of Comparative Example 1) Comparative Example 1 in Table 1 corresponds to light guiding film 10X according to Comparative Example 1 shown in FIG.

[0094] (Specifications of Comparative Example 2) Comparative Example 2 in Table 1 corresponds to light guiding film 10Y according to Comparative Example 2 shown in FIG.

[0095] (Evaluation Results of Each Example and Comparative Example) As shown in Table 1, in Examples 1 to 10, the incidence efficiency was 15% or more and the luminance value was judged to be C or more. In Comparative Examples 1 and 2, the incidence efficiency was 10% and the luminance value was judged to be D. From these results, it was found that the incidence efficiency of light from the light source to light guiding film 10 was high when the thickness of film 1 was 1500.0 μm or less and the angle α satisfied 60 degrees≦α≦120 degrees. It was also found that the luminance value of the light emitted from light guiding film 10 was high, and from another perspective, the light emitted from light guiding film 10 became brighter. Furthermore, it was found that in Examples 8 and 9, the incidence efficiency was 30% or more and the luminance value was judged to be A, and the best results were obtained.

[0096] Furthermore, in light guiding film 10, it is preferable to satisfy 0.1 mm≦H / W≦3.0 mm, where H is the length of light incident surface 23 in the direction along normal line N1 to second main surface 12 and W is the length of light emitting surface 51 of light source 50 in the direction along normal line N1 to second main surface 12. By satisfying this condition, light guiding film 10 can improve the efficiency of light incidence into film 1.

[0097] Furthermore, in light guiding film 10, it is preferable that 8.0 mm≦L≦100.0 mm is satisfied, where L is the length of light incident member 2 in the direction along normal N2 to light emitting surface 51. By satisfying this condition, light guiding film 10 can improve the efficiency of light incidence into film 1.

[0098] [Other preferred variations] The light guiding film 10 according to the embodiment may have a low refractive index layer disposed on one side of the light guiding film 10 and having a refractive index lower than that of the first transmission layer 110 and the second transmission layer 130. The low refractive index layer preferably has a refractive index of 1.30 or less. From the viewpoint of reducing the presence of the light guiding film 10 when it is placed on an adherend, the total thickness from the surface of the light guiding film 10 on the side opposite to the side on which the low refractive index layer is disposed to the surface of the light guiding film 10 on the side on which the low refractive index layer is disposed is preferably 1500.0 μm or less.

[0099] The adherend on which the light guiding film 10 is disposed is not limited to glass, but may be an electronic substrate such as a liquid crystal cell, or a non-light-transmitting member such as a ceiling, a wall, or a floor. The light extraction layer 150 is not limited to extracting light to the side opposite to the side on which the adherend is located, but may extract light to the side on which the adherend is located. In this case, if the adherend has high light transmittance, the extracted light may pass through the adherend, and if the adherend has low light transmittance, the adherend may reflect the light.

[0100] A substrate film may be further disposed on the first main surface 11. The substrate film may be a hard coat layer or an anti-reflection layer. Furthermore, a low refractive index layer may be provided between the light extraction layer 150 and the substrate film.

[0101] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0102] The ordinal numbers, quantities, and other numbers used in the description of the embodiments are all provided as examples to specifically explain the technology of the present invention, and the present invention is not limited to the exemplified numbers. Furthermore, the connection relationships between the components are provided as examples to specifically explain the technology of the present invention, and do not limit the connection relationships that realize the functions of the present invention.

[0103] The light guiding film according to the embodiment can increase the incidence efficiency of light from a light source, and can be combined with a light source and placed on architectural components such as glass, windows, walls, floors, and ceilings to brightly illuminate the interior or exterior space of a building. In addition, by placing it on a partition, it can be used to suitably partition an interior space or hide a desired space. In addition, by placing it on a glass substrate of a display device such as a liquid crystal panel or an organic EL (Electro Luminescence) display panel, it can brighten backlight illumination in the display device. In addition, the light guiding film 10 can also be used as a flexible lighting film without being placed on an adherend. Furthermore, the light guiding film according to the embodiment can provide new uses other than those mentioned above.

[0104] A surface illumination device can also be configured by a light guiding film according to the embodiment and a light source arranged so that light is incident on the light incident surface of the light guiding film directly or via a light incident member.

[0105] For example, aspects of the present invention are as follows. <1> a light guiding film comprising: a film including a first main surface, a second main surface disposed on the opposite side of the first main surface, and end surfaces intersecting the first main surface and the second main surface, and guiding light entering the film; and a light entrance member including an upper surface, a lower surface disposed on the opposite side of the upper surface, and a light entrance surface intersecting the upper surface, the lower surface being disposed on the first main surface such that the lower surface faces the first main surface, and allowing light emitted from a light source including a light emitting surface to enter the film, wherein a thickness of the film is 1500 μm or less, and an angle α between the upper surface of the light entrance member disposed on the first main surface of the film and a normal to the second main surface satisfies 60 degrees≦α≦120 degrees. <2> The upper surface of the light incidence member is a flat surface. <1> 2. The light guiding film according to claim 1 . <3> a reflecting member is disposed on an opposing surface of the light incident member that is located on the opposite side to the light incident surface; <1> or the above <2> 2. The light guiding film according to claim 1 . <4> The light incident surface is inclined so as to move away from the light source as it moves away from the first main surface. <1> From the above <3> 13. The light guiding film according to claim 12, wherein the light guiding film is a light guiding film having a thickness of 100 nm or less. <5> The light incidence member includes a convex portion that protrudes downward from the lower surface and is disposed between the light source and the end surface of the film, and a part of the light from the light source is incident on the inside of the film through the convex portion. <1> From the above <4> 13. The light guiding film according to claim 12, wherein the light guiding film is a light guiding film having a thickness of 100 nm or less. <6> When the length of the light incident surface in the direction along the normal line of the second main surface is H and the length of the light emitting surface in the direction along the normal line of the second main surface is W, 0.1 mm≦H / W≦3.0 mm is satisfied. <1> From the above <5> 13. The light guiding film according to claim 12, wherein the light guiding film is a light guiding film having a thickness of 100 nm or less. <7> The length of the light incident member in the direction along the normal line of the light emitting surface is defined as L, and the length satisfies 8.0 mm≦L≦100.0 mm. <1> From the above <6> 13. The light guiding film according to claim 12, wherein the light guiding film is a light guiding film having a thickness of 100 nm or less. <8> a light source including a light emitting surface; <1> From the above <7> and a light guiding film according to any one of claims 1 to 5. [Explanation of symbols]

[0106] 1. Film 11 First main surface 12 Second main surface 13 End face 2. Light input member 21 Top side 22 Bottom side 23 Light incidence surface 24 Opposite Surface 25 Convex 251 Lower surface of convex part 252 Convex exit surface 3 Reflective material 10 Light guiding film 50 light source 51 Light-emitting surface 60 Wiring board 100 Lighting Equipment 110 1st transmission layer 120 1st adhesive layer 130 2nd transmission layer 140 Second adhesive layer 150 Light extraction layer 151 Light extraction part Bx, Fx, Fy, L, H, M, T, W Length N1 Normal to the second principal surface N2 Normal to the light-emitting surface Px, Py pitch D, E interval q Height r width Mp case M1 Mounting stand M2 storage unit Mh1, Mh2 thickness My1, My2 length α angle θa, θb angle

Claims

1. A film including a first main surface, a second main surface disposed on an opposite side of the first main surface, and an end surface intersecting each of the first main surface and the second main surface, the film guiding light incident thereto; a light incidence member including an upper surface, a lower surface disposed on the opposite side of the upper surface, and a light incidence surface intersecting the upper surface, the lower surface being disposed on the first main surface such that the lower surface faces the first main surface, and causing light emitted from a light source including a light emitting surface to enter the inside of the film; The thickness of the film is 1500 μm or less, A light-guiding film, wherein an angle α between the upper surface of the light-incident member disposed on the first main surface of the film and a normal to the second main surface satisfies 60 degrees≦α≦120 degrees.

2. The light guiding film of claim 1 , wherein the top surface of the light input member is a flat surface.

3. The light guiding film according to claim 1 , wherein a reflective member is disposed on an opposing surface of the light incident member that is located opposite to the light incident surface.

4. The light guiding film of claim 1 , wherein the light incidence surface is inclined so as to move away from the light source with increasing distance from the first major surface.

5. the light incidence member includes a convex portion that protrudes downward from the lower surface and is disposed between the light source and the edge surface of the film; The light guiding film of claim 1 , wherein a portion of the light from the light source is incident on the inside of the film through the protrusions.

6. 2. The light-guiding film of claim 1 , wherein H is the length of the light-incident surface in a direction along the normal to the second main surface, and W is the length of the light-emitting surface in a direction along the normal to the second main surface, and 0.1 mm≦H / W≦3.0 mm is satisfied.

7. The light guiding film of claim 1 , wherein L is a length of the light incident member in a direction along a normal to the light emitting surface, and satisfies 8.0 mm≦L≦100.0 mm.

8. a light source including a light emitting surface; A lighting device comprising: a light guiding film according to any one of claims 1 to 7.

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