Lighting device

Abstract

To reduce luminance unevenness. The lighting device has: a light guide body provided with a cavity inside; a light source that emits light toward an end surface of the light guide body; and a light diffusion member disposed between the end surface and the light source to diffuse and transmit light from the light source, the light diffusion member having a half angle of at least one cross section of a bidirectional transmittance distribution function measured with light having an incident angle of 0° of 50° or more.

Description

Technical Field

[0001] This invention relates to a lighting device. Background Technology

[0002] For example, Patent Document 1 discloses an illumination device having a first prism pattern and a second prism pattern that intersect each other at right angles between the light source and the light guide plate. Patent Document 2 discloses an illumination device having a moth-eye pattern and protrusions on the light-incident surface of the light guide plate into which light from the light source enters.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 4691543

[0006] Patent Document 2: Japanese Patent No. 6068747 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] The purpose of this invention is to reduce uneven brightness.

[0009] Technical solutions for solving technical problems

[0010] An illumination device according to one aspect of the present invention comprises: a light guide having a cavity therein; a light source emitting light toward an end face of the light guide; and a light diffusion member disposed between the end face and the light source, allowing light from the light source to diffuse through, wherein the half-value angle of at least one cross section of a bidirectional transmittance distribution function measured by the light diffusion member with light incident at an angle of 0° is 50° or more.

[0011] Invention Effects

[0012] According to the present invention, uneven brightness can be reduced. Attached Figure Description

[0013] Figure 1 This is a schematic top view showing a first example of a lighting device according to an embodiment.

[0014] Figure 2 yes Figure 1 A schematic cross-sectional view of line II-II in the diagram.

[0015] Figure 3A This is a diagram showing the diffused light from the light-diffusing component of the lighting device in the embodiment.

[0016] Figure 3BThis is a diagram illustrating a method for measuring the bidirectional transmittance distribution function of diffused light from a light-diffusing component of a lighting device based on an embodiment.

[0017] Figure 4 This is a graph illustrating the half-value angle of the bidirectional transmittance distribution function of the diffused light of the light-diffusing component of the lighting device based on the embodiment.

[0018] Figure 5 This is a schematic cross-sectional view of the cavity provided by the lighting device in the embodiment.

[0019] Figure 6 This is a schematic top view showing a first example of the cavity provided by the lighting device of the embodiment.

[0020] Figure 7 This is a schematic top view showing a second example of the cavity provided by the lighting device in the embodiment.

[0021] Figure 8 This is a diagram illustrating the method for evaluating the uneven brightness of the lighting device in the embodiments and comparative examples.

[0022] Figure 9 This is a diagram showing the evaluation area of ​​uneven brightness of the lighting devices in the embodiments and comparative examples.

[0023] Figure 10 This is a diagram showing an example of the measurement results for brightness distribution.

[0024] Figure 11 This is a diagram showing the image of the emitted light from the lighting device in Comparative Example 4.

[0025] Figure 12 This is a diagram showing an image of the emitted light from the lighting device of Embodiment 4.

[0026] Figure 13 This is a schematic cross-sectional view showing a second example of a lighting device according to an embodiment. Detailed Implementation

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to denote the same constituent elements, and repeated descriptions are omitted where appropriate.

[0028] The embodiments shown below are examples of lighting devices used to embody the technical concept of the present invention, and are not intended to limit the invention to the embodiments shown below. Regarding the dimensions, materials, shapes, and relative arrangements of the constituent components described below, unless the description is limited to a specific manner, it is not intended to limit the scope of the invention thereto, but is merely illustrative. Furthermore, the size and positional relationships of the components shown in the accompanying drawings are sometimes exaggerated for clarity.

[0029] In the accompanying drawings shown below, orthogonal coordinates with X, Y, and Z axes are used to represent direction. The X, Y, and Z axes are approximately orthogonal to each other. The direction in which the arrow representing the X-axis points is labeled as +X direction or +X side, and the direction opposite to the +X direction is labeled as -X direction or -X side. The direction in which the arrow representing the Y-axis points is labeled as +Y direction or +Y side, and the direction opposite to the +Y direction is labeled as -Y direction or -Y side. The direction in which the arrow representing the Z-axis points is labeled as +Z direction or +Z side, and the direction opposite to the +Z direction is labeled as -Z direction or -Z side. The X-direction corresponds to the "parallel direction" of the arrangement of the plurality of light sources in the lighting device of the embodiment, and also corresponds to the "length direction" of the end face of the light guide in the lighting device of the embodiment.

[0030] The Z-direction along the Z-axis represents the direction of the normal to the emitting surface of the illumination device in this embodiment. In this specification, "viewing from above" means observing the object from the +Z direction. Furthermore, the +Z direction is referred to as "up," and the -Z direction as "down." However, the above directional representations are merely for illustrative purposes to indicate relative positional relationships and do not limit the direction of the embodiment.

[0031] In this specification and claims, "generally parallel" means that the absolute value of the angular offset from the parallel state is 0 degrees or more and 10 degrees or less. "Generally orthogonal" means that the absolute value of the angular offset from the orthogonal state is 0 degrees or more and 10 degrees or less. "Arrangement" is not limited to direct contact, but also includes indirect arrangement, such as via other components. Furthermore, in this specification, "thickness" refers to the length of the object in the Z direction. Additionally, in this specification, cross-sectional views are sometimes shown as end views showing only the cross-section.

[0032] [Implementation Method]

[0033] <Overall Structure of the Lighting Device in the Embodiment>

[0034] Reference Figures 1-4 The overall structure of the lighting device according to the embodiment will be described. Figure 1 This is a schematic top view showing a first example of the lighting device 100 according to the embodiment. Figure 2 yes Figure 1 A schematic cross-sectional view of line II-II in the diagram. Figure 3A This is a diagram illustrating an example of the diffused light Lc of the light diffusion member 20 included in the lighting device 100 of the embodiment. Figure 3BThis is a diagram illustrating an example of a method for measuring the bidirectional transmission distribution function (BTDF) of the diffused light Lc of the light diffusion member 20 included in the lighting device 100 of the embodiment. Figure 4 This is a diagram illustrating the half-value angle θ0 of the BTDF of the diffused light Lc of the light diffusion member 20 included in the lighting device 100 of the embodiment. Furthermore, BTDF is a six-dimensional function that represents the characteristics of the object surface related to transmission, with the position of the object surface, the incident direction, and the transmission direction as variables.

[0035] The lighting device 100 includes: a laminate 80 with a light guide layer, which has a cavity 64 inside; a light source LS that emits light Lr toward the end face 81 of the laminate 80 with the light guide layer; and a light diffusion member 20 disposed between the end face 81 and the light source LS, which diffuses and transmits the light Lr from the light source LS. Furthermore, in Figure 2 In the example shown, the dashed arrows represent a portion of the light Lr emitted from the light source LS and a portion of the diffused light Lc from the light diffusion component 20, respectively. Figure 1 In the example shown, the light source LS includes multiple light sources LS arranged at predetermined intervals in a parallel direction corresponding to the X direction.

[0036] Figure 2 The illustrated laminate 80 with a light guide layer includes a light guide layer 10, a laminate 70, and a first adhesive layer 52. The first adhesive layer 52 is disposed between the light guide layer 10 and the laminate 70, and is used to bond the light guide layer 10 and the laminate 70. The laminate 70 includes a substrate 30 and a orientation conversion layer 60. The orientation conversion layer 60 includes a shaping film 62 and a second adhesive layer 54. The second adhesive layer 54 is disposed between the shaping film 62 and the substrate 30, and is used to bond the shaping film 62 and the substrate 30. The substrate 30 and the main surface 621 of the shaping film 62 are arranged opposite each other. The light guide layer 10 and the shaping film 62 are arranged opposite each other. Furthermore, the shaping film 62 is a film manufactured without cutting raw materials. In the description of this embodiment, the case where the light guide is a laminate 80 with a light guide layer is illustrated; however, if there is a cavity 64 inside the light guide, the light guide does not need to be a laminate with a light guide layer. The light guide may consist solely of a laminate 80 having an internal cavity 64, or it may not be a laminate.

[0037] like Figure 2As shown, a plurality of cavities 64 are provided inside the orientation conversion layer 60. Each cavity 64 has a first inclined surface ISa and a second inclined surface ISb disposed in the Y direction on the side opposite to the first inclined surface ISa. Air, for example, exists inside the cavity 64. A plurality of recesses 622 are provided on the main surface 621 of the shaping film 62. The open portions of each of the recesses 622 are blocked by a substrate 30 disposed on the main surface 621 via a second adhesive layer 54, thereby forming the cavity 64. The cavity 64 may also be referred to as an internal space or an air cavity.

[0038] The lighting device 100 is used, for example, when the laminate 80 with the light guide layer is disposed on an adhered object such as glass, window, wall, floor, or ceiling. Light Lr emitted from the light source LS of the lighting device 100 diffuses through the light diffusion member 20. The diffused light Lc diffused by the light diffusion member 20 enters the interior of the laminate 80 with the light guide layer through the end face 81 and is guided within the laminate 80. A portion of the diffused light Lc guided within the laminate 80 is reflected by either the first inclined surface ISa or the second inclined surface ISab of the cavity 64 in the -Z direction, and exits through the exit surface 82 of the laminate 80 intersecting the end face 81 in the -Z direction, intersecting the main surface 621 of the shaping film 62. The lighting device 100 can illuminate an indoor space, etc., in which the light-guided laminate 80 is disposed, by using diffused light Lc emitted substantially from the exit surface 82 of the laminate 80 with a light guide layer.

[0039] In a lighting device having a laminated body with a light guide layer having an internal cavity, when the laminated body with the light guide layer is viewed from above, uneven brightness sometimes occurs near the end face of the laminated body with the light guide layer where light is incident from the light source. This uneven brightness includes band-shaped dark areas extending along the length direction (e.g., the X direction) of that end face. It is believed that this uneven brightness, including band-shaped dark areas, is caused by areas near the end face of the laminated body with the light guide layer that are not reached by light incident into the interior of the laminated body, or by areas where the light does not pass through the interior of the laminated body due to the height of the directivity of the light reflected from the cavity. This uneven brightness, including band-shaped dark areas, degrades the quality of the lighting device.

[0040] In the lighting device 100 of this embodiment, the half-value angle of at least one cross-section of the BTDF measured when light with an incident angle of 0° is incident on the light diffusion member 20 is 50° or more. Furthermore, "at least one cross-section (profile cross-section) of the BTDF" refers to the BTDF in the cross-section including the central axis 20C of the light diffusion member 20, which is considered as three-dimensional data. Figure 3AThis indicates that xenon light Lx emitted from the xenon light source Xe enters the light diffuser 20 at an incident angle of 0°, is diffused by the light diffuser 20, and passes through the light diffuser 20. The incident angle of 0° is the angle corresponding to the direction parallel to the normal NL of the light diffuser 20.

[0041] In BTDF measurement, a goniometric photometer (GP-4) manufactured by Nikka Electrometry Co., Ltd. can be used. Xenon light (Lx) can be obtained using light at a wavelength of 555 nm extracted from a xenon source (Xe) using a bandpass filter. For example... Figure 3B As shown, in the BTDF measurement, xenon light Lx is incident on the light diffusion member 20 at an incident angle of 0°. Furthermore, on the exit side (+Y side) of the light diffusion member 20, the receiver of a goniometer manufactured by Nikka Electric Measurement Co., Ltd. is guided along a hemispherical orbit f(θ, The measurement is performed by moving the object to one side, thereby obtaining the orbital f(θ) of the hemisphere. The corresponding BTDF. θ is the elevation angle (diffusion angle). It is the azimuth angle. The diffused light Lc diffuses in and passes through the light diffuser 20 according to the BTDF of the light diffuser 20.

[0042] Figure 4 Indicates the orbit f(θ, in the hemisphere) In ), This example illustrates the relationship between θ (elevation angle (diffusion angle)) and light intensity values ​​for a BTDF profile cross-section when θ is set to 0° and moved to a position above -90° and below +90°. The light intensity values ​​are measured in 10° increments. Figure 4 The vertical axis represents the normalized light intensity value with the maximum intensity value set to 1. The half-value angle θ0 refers to the BTDF of the diffuse light Lc when the normalized light intensity value is 0.5.

[0043] In the lighting device 100 of this embodiment, by using a light diffusion member 20 whose half-value angle in at least one profile section of the BTDF, measured using light with an incident angle of 0°, is 50° or more, the directivity of the diffused light Lc emitted from the light diffusion member 20 and entering the interior of the laminate 80 with the light guide layer can be reduced. By reducing the directivity of the diffused light Lc, the area where the diffused light Lc entering the interior of the laminate 80 with the light guide layer cannot reach is reduced. Therefore, in this embodiment, brightness unevenness, including banded dark areas, can be reduced. Furthermore, by reducing brightness unevenness, the quality of the lighting device 100 can be improved.

[0044] exist Figure 3A and Figure 3BIn the example shown, at least one profile section of the BTDF is a YZ section that includes the central axis 20C of the light diffuser 20 and is orthogonal to the X direction. The central axis 20C of the light diffuser 20 is an axis that passes through the center 20P of the light diffuser 20 and is parallel to the normal NL of the light diffuser 20. By setting the aforementioned YZ section as "at least one profile section of the BTDF," for example, compared to setting the section including the central axis 20C of the light diffuser 20 and sections other than the aforementioned YZ section as "at least one profile section of the BTDF," the directivity of the diffused light Lc emitted from the light diffuser 20 and entering the interior of the laminate 80 with the light guide layer can be reduced.

[0045] In the lighting device 100, on the hemispherical orbit f(θ, In ), Set to 0°, so that =0° along the normal direction of the exit surface 82 that intersects with the end face 81. Therefore, light can be diffused particularly in the normal direction of the exit surface 82 where light diffusion is desired, thus making it easier to reduce brightness unevenness. However, The orientation of 0° does not necessarily have to be along the normal direction of the exit surface 82. The light diffusion component 20 can be configured as an isotropic BTDF or as anisotropic.

[0046] Additionally, in the lighting device 100, such as Figure 2 As shown, the laminate 80 with a light guide layer includes an exit surface 82 intersecting with an end face 81, which guides diffused light Lc that enters the interior of the laminate 80 with a light guide layer through the end face 81. A cavity 64 reflects a portion of the diffused light Lc guided inside the laminate 80 towards the exit surface 82. The diffused light Lc reflected by the cavity 64 exits from the laminate 80 with a light guide layer through the exit surface 82. Therefore, in this embodiment, a surface illumination type lighting device 100 is provided that allows light entering from the end face 81 of the laminate 80 with a light guide layer to exit substantially entirely from the exit surface 82.

[0047] Furthermore, the lighting device 100 does not have components such as a diffuser plate or prism array that further diffuse the diffused light Lc emitted from the exit surface 82 of the laminate with the light guide layer 80. As a result, the structure of the lighting device 100 can be simplified.

[0048] <Detailed Structure of Lighting Device 100>

[0049] The structure of the lighting device 100 will now be described in detail. The lighting device 100 has a light distribution control structure having multiple cavities 64. The first inclined surface ISa of each of the multiple cavities 64 directs a portion of the diffused light Lc guided within the laminate 80 with the light-guiding layer toward the exit surface 82 via total internal reflection (TIR). Furthermore, the diffused light Lc is refracted according to the refractive index of the material constituting the interface when passing through the interface.

[0050] The laminate 80 with the light guide layer is configured to emit diffused light Lc with a desired light distribution from the emission surface 82 via a light distribution control structure. The light distribution can be controlled, for example, by adjusting the cross-sectional shape, planar shape, size, arrangement density, and distribution of the cavity 64.

[0051] The laminate 80 with the light guide layer has a visible light transmittance of 60% or more and a haze value of less than 30%. The visible light transmittance is preferably 70% or more, more preferably 80% or more. The haze value is preferably less than 10%, more preferably 5% or less. The laminate 80 with the light guide layer has high visible light transmittance and low haze value, thus allowing objects to be seen (displayed) through the laminate 80 with the light guide layer. Visible light is light with a wavelength of 380 nm or more and 780 nm or less. The visible light transmittance and haze value can be measured using a haze meter (Murakami Color Technology Research Institute: trade name HM-150), etc.

[0052] When the light guide layer 10 is viewed from the normal direction of the exit surface 82, the ratio of the area of ​​the plurality of cavities 64 to the area of ​​the light guide layer 10 (occupancy rate) is preferably 1% or more and 80% or less. The upper limit of the above-mentioned occupancy rate is more preferably 50% or less, further preferably 45% or less, and preferably 30% or less, more preferably 10% or less, and further preferably 5% or less, in order to obtain at least one of high transmittance and low haze value.

[0053] For example, a haze value of 30% can be obtained when the cavity occupancy rate is 50%. Furthermore, the cavity occupancy rate can be uniform or it can increase with increasing distance, ensuring that the brightness does not decrease even as the distance from the light source LS increases. For mass production using roll-to-roll or roll-to-sheet methods, a uniform cavity occupancy rate is preferred.

[0054] In the laminate 80 with the light guide layer, the light guide layer 10 and the shaping film 62 are bonded together by a first adhesive layer 52. Additionally, the substrate 30 is bonded to the shaping film 62 by the shaping film 62 and a second adhesive layer 54 constituting the direction conversion layer 60. The light guide layer 10 and the substrate 30 can be transparent substrates or films.

[0055] exist Figure 1 In the example shown, multiple cavities 64 are discretely arranged in the X and Y directions of the light guide layer 10. However, the discrete arrangement of the cavities 64 can be appropriately set according to the shape of the light guide layer 10 or the required light distribution.

[0056] exist Figure 1 In the example shown, multiple cavities 64, having substantially the same shape and convex in the same direction, are discretely and periodically arranged throughout the region in the X and Y directions. In this case, the spacing Px is preferably, for example, 10 μm or more and 500 μm or less, and the spacing Py is preferably, for example, 10 μm or more and 500 μm or less. Figure 1 In the example shown, the laminate 80 with the light guide layer also has cavities 64 that are staggered by 1 / 2 of the spacing Px in the X direction and by 1 / 2 of the spacing Py in the Y direction.

[0057] A light source LS is, for example, an LED (Light Emitting Diode) device. Multiple LED devices are arranged in the X direction. There are no particular restrictions on the number and arrangement of LEDs. Furthermore, a light source LS is not limited to LED devices; it can also be a halogen lamp, etc.

[0058] Reference Figures 5-7 The detailed structure of cavity 64 is described. Figure 5 This is a schematic cross-sectional view showing an example of cavity 64. Figure 6 This is a schematic top view representing the first example of cavity 64. Figure 7 This is a schematic top view representing a second example of cavity 64.

[0059] Figure 5 The cross-sectional shape of the cavity 64 shown is approximately triangular. However, the cross-sectional shape of the cavity 64 is not limited to approximately triangular; it can also be approximately trapezoidal, etc. Figure 5 In the example shown, the tilt angle θa of the first inclined surface ISa is larger than the tilt angle θb of the second inclined surface ISb.

[0060] The tilt angle θa of the first tilted surface ISa on the light source LS side is, for example, 10° or more and 70° or less. If the tilt angle θa is less than 10°, the controllability of light distribution decreases, and the light extraction efficiency also decreases. On the other hand, when the tilt angle θa exceeds 70°, the processing of the shaping film 62 sometimes becomes difficult. By setting the tilt angle θa to 10° or more and 70° or less, the light extraction efficiency can be improved, and the processing of the shaping film 62 can be made easier.

[0061] The tilt angle θb of the second tilted surface ISb is, for example, 50° or more and 100° or less. If the tilt angle θb is less than 50°, stray light may sometimes be generated in an undesirable direction. On the other hand, if the tilt angle θb exceeds 100°, the processing of the shaping film 62 may become difficult. By setting the tilt angle θb to 50° or more and 100° or less, the light extraction efficiency can be improved, and the processing of the shaping film 62 can be made easier.

[0062] Figure 6 The first inclined surface ISa shown is a curved surface that bulges towards the light source LS when viewed from above. Here, the light emitted from the multiple LED devices constituting the light source LS has a spread relative to the Y direction. Therefore, when the first inclined surface ISa has a curved surface bulging towards the light source LS, the first inclined surface ISa acts on the light uniformly. Furthermore, when a coupling optical system is provided between the light source LS and the end face 81 of the laminate 80 with the light guide layer, the first inclined surface ISa can also be parallel to the X direction when light with high parallelism (light with small spread relative to the Y direction) is incident.

[0063] like Figure 6 and Figure 7 As shown, the length L of the cavity 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 preferably, for example, more than twice the width W. The height H is preferably 1 μm or more and 100 μm or less. Furthermore, depending on the formation including the top view, it has... Figure 6 The machining accuracy of the shaped film 62 when forming the recess 622 of the shape shown sometimes results in a shape that, when viewed from above, has... Figure 7 The recess 622 is shown in the figure. Even in this case, the shape of the cavity 64 when viewed from above can be determined by the length L and the width W.

[0064] The shaped film 62 can be manufactured according to the method described in Japanese Patent Application Publication No. 2013-524288. Specifically, the surface of a polymethyl methacrylate (PMMA) film is coated with a varnish (FINECURE RM-64 manufactured by Sanyo Chemical Industries, Ltd.), an optical pattern is embossed on the film surface containing the varnish, and then the varnish is cured, thereby manufacturing the target shaped film 62. The total thickness of the shaped film 62 is, for example, 130 μm.

[0065] The light guide layer 10 is formed of a known material with high transmittance of visible light. For example, it is formed of acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC) resins, cycloolefin resins, or glass (quartz glass, alkali-free glass, borosilicate glass, etc.). The refractive index nGP of the light guide layer 10 is, for example, 1.40 or higher and 1.80 or lower. It should be noted that, unless otherwise specified, the refractive index refers to the refractive index measured using an ellipsometer at a wavelength of 550 nm. The thickness of the light guide layer 10 can be appropriately set according to the application. For example, the thickness of the light guide layer 10 is 0.05 mm or higher and 50 mm or lower.

[0066] The thickness of the substrate 30 is, for example, 1 μm or more and 1000 μm or less, preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 80 μm or less. The refractive index of the substrate 30 is preferably 1.40 or more and 1.70 or less, and more preferably 1.43 or more and 1.65 or less.

[0067] The thicknesses of the first adhesive layer 52 and the second adhesive layer 54 are each independently, for example, 0.1 μm or more and 100 μm or less, preferably 0.3 μm or more and 100 μm or less, and more preferably 0.5 μm or more and 50 μm or less. The refractive indices of the first adhesive layer 52 and the second adhesive layer 54 are each independently preferably 1.42 or more and 1.60 or less, more preferably 1.47 or more and 1.58 or less. Furthermore, the refractive indices of the first adhesive layer 52 and the second adhesive layer 54 are preferably close to the refractive index of the light guide layer 10 or the shaping film 62 to which they are attached, and the absolute value of the difference in refractive indices is preferably 0.2 or less.

[0068] The second adhesive layer 54 is preferably bonded without filling the recesses 622 of the shaped film 62. As an adhesive suitable for forming the second adhesive layer 54, adhesives described in the applicant's international applications PCT / JP 2021 / 006452, PCT / JP 2021 / 006453, or Japanese Patent Application No. 2021-025496 are preferred. The disclosures of these applications are incorporated herein by reference in their entirety. Polyester-based adhesives described in Japanese Patent Application No. 2021-025496 are particularly preferred.

[0069] <Evaluation Methods for Uneven Brightness>

[0070] Next, refer to Figures 8-10 The evaluation method for uneven brightness in the lighting device 100 is explained. Figure 8 This is a diagram illustrating an example of the method for evaluating the brightness unevenness of the lighting device in the embodiments and comparative examples. Figure 9 This is a diagram illustrating an example of the brightness unevenness evaluation region P of the lighting device in the embodiment and the comparative example. Figure 10This is a diagram showing an example of the measurement results for brightness distribution.

[0071] exist Figure 8 In the illustrated method for evaluating brightness non-uniformity, a two-dimensional spectroradiometer 600 is used to measure the brightness of light emitted from the light source LS, diffused and transmitted through the light diffusion component 20, guided within the laminate 80 with the light guide layer, and emitted approximately as a whole from the exit surface 82. The two-dimensional spectroradiometer 600 used is the Topcon SR-5000 manufactured by Topcon Corporation. The distance Tz from the exit surface 82 to the two-dimensional spectroradiometer 600 is 0.7 m.

[0072] Extracting from the image obtained by the two-dimensional spectroradiometer 600, and... Figure 9 The linear image region corresponding to the brightness unevenness evaluation region P is shown, and the brightness distribution in this linear image region is evaluated. Figure 9 The interval Δ in the figure refers to the interval between the light-emitting surface LS0 of the light source LS and the surface of the light-emitting side of the light diffusion component 20.

[0073] Figure 10 This is an example of the measurement results showing the luminance distribution in the luminance non-uniformity evaluation region P. Figure 10 The horizontal axis represents Figure 9 The image shows the position within the brightness unevenness evaluation region P. Position 0 mm is the closest position to the light source LS within region P. A larger position value indicates greater distance from the light source LS.

[0074] exist Figure 10 In the example shown, the highest brightness value Q1 is located around 10mm, and the lowest brightness value Q2 is located around 20mm. The brightness variation decreases further away from 20mm. The lowest brightness value Q2 is the brightness value obtained at a point of minimal brightness in the brightness unevenness evaluation area P, further away from the location where the highest brightness value Q1 is obtained. The smaller the brightness ratio obtained by dividing the lowest brightness value Q2 by the highest brightness value Q1, the greater the brightness unevenness, including bands of shadows. This brightness ratio is used as one of the evaluation indicators in the evaluation of brightness unevenness.

[0075] <Evaluation results of uneven brightness>

[0076] Table 1 shows the main specifications and evaluation results of the lighting devices of Comparative Examples 1 to 8 and Examples 1 to 5.

[0077] [Table 1]

[0078]

[0079] In Table 1, "End face processing of the laminate with light guide layer" indicates whether the end face of the laminate with light guide layer into which light from the light source enters has been processed, and the type of shape after processing. In Comparative Example 2, a shape along the transverse direction is processed on the end face of the laminate with light guide layer. Figure 9 Multiple grooves extending in the X direction. In Comparative Example 3, grooves extending longitudinally are machined on the end face of the laminate with the light guide layer. Figure 9 Multiple grooves extending in the Z direction. In Comparative Example 4, multiple grid-like grooves extending longitudinally and laterally were machined on the end face of the laminate with the light guide layer. In Comparative Example 1 and Examples 1 to 5, the end face of the laminate with the light guide layer was not machined.

[0080] "Presence or absence of a light diffusion component" indicates whether a light diffusion component is disposed between the light source and the end face of the laminate with the light guide layer. In Comparative Examples 1 to 6, no light diffusion component was disposed. In Comparative Examples 7 and 8, and Examples 1 to 5, a light diffusion component was disposed. It should be noted that in the configuration of the light diffusion component, the surface of the light diffusion component opposite to the end face of the laminate with the light guide layer is configured such that the light diffusion component is in contact with the end face of the laminate with the light guide layer. In other words, the distance between the light diffusion component and the end face of the laminate with the light guide layer is set to approximately 0 mm.

[0081] "Half-value angle of diffused light (°)" indicates the half-value angle of the BTDF of the diffused light emitted from the light diffusion component. In Comparative Examples 1 to 6, since no light diffusion component was provided, it is indicated as "—". In Comparative Examples 7 and 8, the half-value angle of diffused light is less than 50°. In Examples 1 to 5, the half-value angle of diffused light is set to 50° or more. The half-value angle of diffused light is preferably 60° or more, 65° or more, 70° or more, 80° or more, or 90° or more, with no particular upper limit, but is 150° or less or 120° or less. The material of the light diffusion component can be, for example, polycarbonate, polystyrene, polyester, silicon, PMMA, etc. For example, by adding particles such as silica or titanium dioxide to these materials and adjusting their addition amount, a desired half-value angle can be achieved. Fine irregularities can also be provided on the surface of the substrate. In addition, a film with specific diffusion can be fabricated using holographic technology. In this embodiment, a milky-white polycarbonate cover attached to the LED aluminum frame (product name LPJ 1707) is used as the light diffusion component 20. This light diffusion component 20 is isotropic. The half-value angle is measured using the method described above.

[0082] "Interval Δ (mm)" indicates Figure 9The distance between the emitting surface LS0 of the light source LS and the surface of the light diffusion member 20 on the light source LS side is shown. In Comparative Examples 1 to 5, since no light diffusion member is provided, it is indicated as "0 mm". In addition, in Comparative Example 6, only "5 mm" indicates the distance between the light source and the end face of the laminate with the light guide layer.

[0083] The half-value angle (°) of the light distribution angle of the light source is expressed as the light distribution angle emitted from the light source. In Comparative Examples 1 to 6 and Examples 1 to 5, the half-value angle of the light distribution angle of the light source is set to 120°.

[0084] "Brightness ratio (%)" is expressed as a percentage. Figure 10 The brightness ratio is obtained by dividing the low brightness value Q2 by the highest brightness value Q1.

[0085] "Uneven brightness judgment" refers to the visual judgment result based on the image obtained from the two-dimensional spectroradiometer 600. The symbols have the following meanings. In addition, "◎", "○", and "△" indicate pass, and "×" indicates fail.

[0086] ◎: No uneven brightness can be seen at all.

[0087] ○: The unevenness of brightness is almost invisible.

[0088] △: Uneven brightness is visible but not obvious.

[0089] ×: Uneven brightness is clearly visible.

[0090] As shown in Table 1, in Comparative Examples 1 to 8, the brightness ratio was 47% or less. Furthermore, in Comparative Examples 1 to 8, the "uneven brightness determination" was "×". Here, Figure 11 This is an example diagram showing an image of the emitted light from the lighting device in Comparative Example 4. For example... Figure 11 As shown, in Comparative Example 4, uneven brightness including banded dark areas S was observed. Similarly, uneven brightness including banded dark areas S was also observed in Comparative Examples 1-3 and Comparative Examples 5-7. Based on the above, it can be concluded that the lighting devices of Comparative Examples 1-8 have significant uneven brightness and are therefore unqualified.

[0091] On the other hand, in Examples 1 to 5, the brightness ratio is 70% or higher. Furthermore, in Examples 1 to 5, the "brightness unevenness determination" is any one of "△", "○", or "◎". Here, Figure 12 This is an example diagram showing an image of the emitted light in the lighting device of Embodiment 4. For example... Figure 12As shown, in Example 4, no brightness unevenness is visible. Similarly, in Example 5, no brightness unevenness is visible. In Examples 1 and 2, brightness unevenness is visible but not significant. In Example 3, brightness unevenness is almost invisible. Based on the above, it can be seen that the lighting devices of Examples 1 to 5 can reduce brightness unevenness. Furthermore, it can be seen that the lighting devices of Examples 1 to 5 are qualified.

[0092] In Table 1, in Examples 2 to 5, where the half-value angle of the BTDF of the diffused light Lc generated by the light diffusion component 20 is 70° or more, the "brightness ratio" is 81% or more. Therefore, from the viewpoint of improving the "brightness ratio" and reducing brightness unevenness, it is preferable that the half-value angle of the diffusion angle of the diffused light Lc generated by the light diffusion component 20 is 70° or more.

[0093] In Table 1, in Examples 3 to 5 where the distance from the light source LS to the light diffusion component 20 is 1 mm or more, the "brightness ratio" is 87% or more, and the "brightness unevenness determination" is "○" or "◎". Therefore, from the viewpoint of improving the "brightness ratio" and reducing brightness unevenness, it is further preferable that the half-value angle of the BTDF of the diffused light Lc generated by the light diffusion component 20 is 70° or more, and the distance from the light source LS to the light diffusion component 20 is 1 mm or more.

[0094] In Table 1, in Examples 4 and 5, where the distance from the light source LS to the light diffusion component 20 is 5 mm or more, the "brightness ratio" is 92% or more, and the "brightness unevenness determination" is "◎". Therefore, from the viewpoint of improving the "brightness ratio" and reducing brightness unevenness, it is particularly preferable that the half-value angle of the BTDF of the diffused light Lc generated by the light diffusion component 20 is 70° or more, and the distance from the light source LS to the light diffusion component 20 is 5 mm or more.

[0095] The upper limit of the distance from the light source LS to the light diffusion component 20 is, for example, less than 20 mm, less than 15 mm, or less than 10 mm.

[0096] [Other preferred variations]

[0097] Figure 13 This is a schematic cross-sectional view showing a second example of an illumination device 100 equipped with a shaped film according to an embodiment. Figure 13 The second example of the lighting device 100 is related to... Figure 1 A portion of the cross section corresponding to line II-II.

[0098] exist Figure 13In the second example of the lighting device 100 shown, the light guide layer 10 is disposed opposite to the substrate 30. Light incident from the light source LS into the laminate 80 with the light guide layer exits from the exit surface 82 located on the side opposite to the light guide layer 10. In the second example of the lighting device 100, these aspects are mainly related to... Figure 2 The first example of the lighting device 100 shown is different.

[0099] exist Figure 13 In the second example of the lighting device 100 shown, the same effect as in the embodiment can also be obtained. It should be noted that the exit surface from which light is emitted from the laminate 80 with the light guide layer can be at least one of the upper surface (the surface on the +Z side) and the lower surface (the surface on the -Z side) of the laminate 80 with the light guide layer.

[0100] The laminate 80 with the light guide layer may have a low-refractive-index layer disposed on one side of the laminate 80 with the light guide layer and having a lower refractive index than the light guide layer 10 or the shaping film 62. Additionally, the laminate 80 with the light guide layer may have a low-refractive-index layer between the shaping film 62 and the substrate 30. The refractive index of the low-refractive-index layer is preferably 1.30 or less. Furthermore, the laminate 80 with the light guide layer may have a hard coating layer and an anti-reflective layer.

[0101] The substrate for the laminate 80 with the light-guiding layer is not limited to glass, but can also be a non-transparent component such as an electronic substrate like a liquid crystal cell, a ceiling, a wall, or a floor. The shaping film 62 can extract light not only from the side opposite to the substrate, but also from the side where the substrate is located. In this case, if the substrate has high light transmittance, the extracted light can pass through it; if the substrate has low light transmittance, it can reflect the light.

[0102] The preferred embodiments have been described in detail above, but are not limited to the embodiments described above. Various modifications and substitutions can be made to the embodiments described above without departing from the scope of the claims.

[0103] The ordinal numbers, quantities, and other numerical values ​​used in the description of the embodiments are all illustrative for the purpose of specifically illustrating the technology of the present invention, and the present invention is not limited to the illustrative numbers. Furthermore, the connection relationships between the constituent elements are illustrative for the purpose of specifically illustrating the technology of the present invention, and are not intended to limit the connection relationships for achieving the functions of the present invention.

[0104] The lighting device of the embodiment can reduce brightness unevenness, and therefore, by being disposed on building components such as glass, windows, walls, floors, and ceilings, it can illuminate the interior or exterior space of a building with reduced brightness unevenness.

[0105] Furthermore, in the lighting device of the embodiment, by using the lighting device as a partition, it is possible to appropriately block indoor partitions or desired spaces. Moreover, by distributing the shaping film, laminate, and light-guiding layer of the lighting device of the embodiment onto the glass substrate of display devices such as liquid crystal panels and organic EL (Electro Luminescence) display panels, it is possible to brighten backlighting and other illumination in the display device. In addition, the lighting device of the embodiment can provide new applications besides those described above.

[0106] The present invention can be described, for example, as follows.

[0107] <1> An illumination device comprising: a light guide having a cavity therein; a light source emitting light toward an end face of the light guide; and a light diffusion member disposed between the end face and the light source, allowing light from the light source to diffuse through, wherein the half-value angle of at least one cross section of a bidirectional transmittance distribution function measured by the light diffusion member with light incident at an angle of 0° is 50° or more.

[0108] <2> According to the above <1> The lighting device, wherein the light source includes a plurality of light sources arranged in a predetermined parallel direction, at least one section of the bidirectional transmittance distribution function is a section including the central axis of the light diffusion component and orthogonal to the parallel direction, and the central axis of the light diffusion component is an axis passing through the center of the light diffusion component and parallel to the normal of the light diffusion component.

[0109] <3> According to the above <1> or the above <2> The lighting device wherein, when light is incident at an angle of 0° on the light diffusion component, the half-value angle of at least one section of the bidirectional transmittance distribution function is 70° or more.

[0110] <4> According to the above <3> The lighting device wherein the distance from the light source to the light diffusion component is 1 mm or more.

[0111] <5> According to the above <3> or the above <4> The lighting device wherein the distance from the light source to the light diffusion component is 5 mm or more.

[0112] <6> According to the above <1> Up to the above <5> The lighting device according to any one of the following methods, wherein the light guide comprises a shaping film and a light guide layer.

[0113] This application claims priority to Japanese Patent Application No. 2024-055660, filed with the Japan Patent Office on March 29, 2024, and includes the entire contents of that Japanese patent application.

[0114] Explanation of reference numerals in the attached figures

[0115] 10: Light guide layer

[0116] 20: Light diffusion component

[0117] 20C: Central axis

[0118] 20P: Center

[0119] 30: Substrate

[0120] 52: First adhesive layer

[0121] 54: Second adhesive layer

[0122] 60: Direction Conversion Layer

[0123] 62: Shaped membrane

[0124] 621: Main side

[0125] 622: concave part

[0126] 64: Cavity

[0127] 70: Layered body

[0128] 80: Laminated body with light guide layer

[0129] 81: End face

[0130] 82: Exit surface

[0131] 100: Lighting device

[0132] 600: Two-dimensional spectroradiometer

[0133] H: Height

[0134] ISa: First Inclined Surface

[0135] ISb: Second inclined surface

[0136] L: Length

[0137] Lc: Diffuse light

[0138] Lr: light

[0139] LS: Light source

[0140] NL: Normal to the light diffusion component

[0141] P: Evaluation area for uneven brightness

[0142] Px, Py: Spacing

[0143] Q1: Maximum brightness value

[0144] Q2: Low brightness value

[0145] S: Anbu

[0146] Tz: Distance

[0147] W: Width

[0148] θa, θb: Inclination angle

[0149] θ0: Half-value angle

[0150] Δ: Interval

Claims

1. A lighting device, characterized in that, have: The light guide has an internal cavity; A light source that emits light toward the end face of the light guide; A light-diffusing component is disposed between the end face and the light source to allow light from the light source to diffuse and pass through. The half-value angle of at least one cross section of the bidirectional transmittance distribution function measured by the light diffusion component when light with an incident angle of 0° is 50° or more.

2. The lighting device according to claim 1, characterized in that, The light source includes multiple light sources arranged in a specified parallel direction. At least one cross section of the bidirectional transmittance distribution function is a cross section that includes the central axis of the light diffusion component and is orthogonal to the parallel directions. The central axis of the light diffusion component is an axis that passes through the center of the light diffusion component and is parallel to the normal of the light diffusion component.

3. The lighting device according to claim 1, characterized in that, The half-value angle of at least one section of the bidirectional transmittance distribution function measured by the light diffusion component when light with an incident angle of 0° is 70° or more.

4. The lighting device according to claim 3, characterized in that, The distance from the light source to the light diffusion component is 1 mm or more.

5. The lighting device according to claim 4, characterized in that, The distance from the light source to the light diffusion component is 5 mm or more.

6. The lighting device according to claim 1, characterized in that, The light guide includes a shaping film and a light guide layer.

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