Illumination device

Abstract

Provided is an illumination device capable of illuminating a wide space. This illumination device has a light source and a light guide that guides light emitted by the light source. The light guide has a cylindrical member and a light extractor that causes the light guided so as to pass through the interior of a wall section in the cylindrical member to be emitted from the interior of the wall section. The cylindrical member has a light incident end surface provided facing the light source at either one of a bottom or a top of the cylindrical member, whereby the light enters the interior of the wall section, and a light emitting section included in a lateral side surface of the cylindrical member orthogonal to the light incident end surface, whereby the light is emitted from the interior of the wall section.

Description

Technical Field

[0001] The present invention relates to a lighting device.

Background Art

[0002] Conventionally, lighting devices for illuminating spaces such as indoors have been known.

[0003] As such a lighting device, a configuration having a light guide body having at least one light incident surface facing a light source and a light emitting surface substantially orthogonal thereto, and a prism sheet disposed on the light emitting surface of the light guide body is disclosed (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the configuration of Patent Document 1, there is room for improvement in illuminating a wide range of spaces.

[0006] An object of the present invention is to provide a lighting device capable of illuminating a wide range of spaces.

Means for Solving the Problems

[0007] In order to solve the above problems, the lighting device of the present invention has a light source and a light guide unit that guides the light emitted by the light source. The light guide unit has a cylindrical member and a light extraction unit that emits the light guided through the inside of the wall portion of the cylindrical member from the inside of the wall portion. The cylindrical member is provided at either the bottom or the top of the cylindrical member facing the light source, and has a light incident end face where the light enters the inside of the wall portion and a light emission portion that is included in the outer surface of the cylindrical member intersecting the light incident end face and from which the light exits from the inside of the wall portion. The cylindrical member has translucency to visible light, and the back of the cylindrical member can be seen through 。

[0008] Alternatively, the lighting device of the present invention has a light source and a light guide unit that guides the light emitted by the light source. The light guide unit has a curved surface member that is a part of a hollow sphere or an ellipsoid of revolution and a light extraction unit that emits the light guided through the inside of the wall portion of the curved surface member from the inside of the wall portion. The curved surface member is provided at the bottom of the curved surface member facing the light source, and has a light incident end face where the light enters the inside of the wall portion and a light emission portion that is included in the outer surface of the curved surface member intersecting the light incident end face and from which the light exits from the inside of the wall portion. The curved surface member has translucency to visible light, and the back of the curved surface member can be seen through 。

Advantages of the Invention

[0009] According to the present invention, a lighting device capable of illuminating a wide area of space can be provided.

Brief Description of the Drawings

[0010]

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Embodiment for Carrying Out the Invention

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and duplicate descriptions will be omitted as appropriate. The following embodiments illustrate a 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 arrangements, etc. of the components described below are not intended to limit the scope of the present invention only thereto, but are intended to be illustrative unless otherwise specified. Also, the sizes and positional relationships of the members shown in the drawings may be exaggerated for clarity of explanation.

[0012] The lighting device according to the embodiment has a light source and a light guide unit that guides the light emitted by the light source. The light guide unit includes either a cylindrical member or a curved surface member that is a part of a hollow sphere or ellipsoid of revolution, and a light extraction unit that emits the light guided through the inside of the wall portion of either the cylindrical member or the curved surface member from the inside of the wall portion.

[0013] Here, the cylindrical member refers to a cylindrical member. The cylindrical member is not limited to a cylindrical body in which the whole in the circumferential direction or the like is continuous, and also includes a cylindrical member in which the end of a plate-like member is not connected to the other end, or a cylindrical member in which a part in the circumferential direction or the like is missing. The cylindrical member includes a cylindrical member having a circular or elliptical cross section perpendicular to the axial direction, and a rectangular tube member having a polygonal cross section perpendicular to the axial direction of the cylindrical member.

[0014] Further, the cylindrical member is provided at either the bottom or the top of the cylindrical member facing the light source, and includes a light incident end face where light enters the inside of the wall portion and a light emitting portion that is included in the outer surface of the cylindrical member intersecting the light incident end face and where light exits from the inside of the wall portion.

[0015] The light emitted by the light source enters the interior of the wall portion in the cylindrical member through the light incident end face and is guided inside the wall portion. A part of the guided light is reflected, scattered, refracted, or diffracted by the light extraction portion toward the outside of the cylindrical member, and exits from the interior of the wall portion in the cylindrical member to the outside through the light emission portion included in the outer surface of the cylindrical member. The lighting device can illuminate the outside of the lighting device with the light emitted from the light emission portion.

[0016] Further, the curved surface member is provided at the bottom of the curved surface member facing the light source, and has a light incident end face through which light enters the interior of the wall portion, and a light emission portion included in the outer surface of the curved surface member that intersects the light incident end face and from which light exits from the interior of the wall portion.

[0017] The light emitted by the light source enters the interior of the wall portion in the curved surface member through the light incident end face and is guided inside the wall portion. A part of the guided light is reflected, scattered, refracted, or diffracted by the light extraction portion toward the outside of the curved surface member, and exits from the interior of the wall portion in the curved surface member to the outside through the light emission portion included in the outer surface of the curved surface member. The lighting device can illuminate the outside of the lighting device with the light emitted from the light emission portion.

[0018] The use, installation location, and illumination object of the lighting device according to the embodiment are not particularly limited. For example, it can be installed on a desk, table, shelf, or its periphery (including the floor, wall, and ceiling of a living room), etc., and used as a space lighting device to illuminate the area on the desk, on the table, inside or outside the shelf, or the space around these, or the interior of a living room, etc. Also, it can be used as ceiling lighting by installing it on the ceiling. Further, it can be used as a footlight to illuminate the floor by installing it on the side wall or ceiling of a passage. Also, it can be used as indirect lighting by illuminating the side wall or ceiling side. Also, it can be used as outdoor lighting to illuminate the surrounding space by installing it outdoors.

[0019] Hereinafter, various embodiments and modifications of a lighting device having a cylindrical member and a lighting device having a curved surface member will be described. For convenience of explanation hereinafter, when the lighting device 100 is viewed from the front side, the lateral direction is defined as the X-axis direction, the depth direction is defined as the Y-axis direction, and the height direction is defined as the Z-axis direction. However, the X-axis direction, Y-axis direction, and Z-axis direction do not limit the orientation of the lighting device 100, and the orientation of the lighting device 100 may be any direction.

[0020] [First Embodiment] <Configuration Example of Lighting Device 100> First, with reference to FIGS. 1, 2A, and 2B, the configuration of the lighting device 100 according to the first embodiment will be described. FIG. 1 is a perspective view for explaining an example of the configuration of the lighting device 100. FIG. 2A is a top view for explaining an example of the configuration of the lighting device 100, and FIG. 2B is a cross-sectional view taken along the A-A' arrow in FIG. 2A. Note that the top view in FIG. 2A is a view of the lighting device 100 viewed from the positive Z-axis side.

[0021] As shown in FIGS. 1, 2A, and 2B, the lighting device 100 includes a base portion 3, a light source 1, and a light guide portion 300. The light guide portion 300 has a cylindrical member 2.

[0022] The base portion 3 is composed of a material such as resin, metal, or wood, and is a plate-like member that fixes the light source 1 and the cylindrical member 2 in the light guide portion 300. The base portion 3 fixes the cylindrical member 2 that abuts on the flat portion of the base portion 3 with an adhesive or the like. A substantially circular groove portion 31 is formed in the flat portion of the base portion 3, and the base portion 3 fixes the light source 1 on the bottom surface of this groove portion 31. Further, the base portion 3 includes wiring on which various electrical elements such as LEDs (Light Emitting Diodes) can be mounted.

[0023] The light source 1 includes a plurality of LEDs 11. The plurality of LEDs 11 are arranged along the groove portion 31 so as to draw a substantially circular shape, and each is fixed on the bottom surface of the groove portion 31.

[0024] Each of the plurality of LEDs 11 is electrically connected to the drive circuit 12 via wiring provided on the base portion 3, and emits light when a drive voltage is applied from the drive circuit 12. The light source 1 can emit an annular light formed by the light emitted by the plurality of LEDs 11.

[0025] The light emitted by the light source 1 may be white light or monochromatic light. Also, various types such as incandescent color, daylight white, and daylight color can be selected from among white lights. However, the configuration of the light source 1 is not limited to those including the LEDs 11. For example, the light source 1 may include a fluorescent lamp or a cold cathode tube formed in a substantially annular shape, or may include a plurality of optical fibers bundled so that the emission end draws a substantially circular shape.

[0026] The drive circuit 12 is supplied with a power supply voltage from a battery composed of various secondary batteries (for example, lithium-ion batteries, lithium polymer batteries, etc.) or a commercial power supply, and applies a drive voltage of the LEDs 11 to the light source 1. Note that the drive circuit 12 may be provided separately from the base portion 3 or may be provided integrally with the base portion 3.

[0027] The cylindrical member 2 included in the light guide portion 300 is a cylindrical member having a cylindrical axis 20 substantially parallel to the Z axis. The cylindrical member 2 includes a wall portion 22 that serves as a side wall of the cylindrical member, and guides light so as to pass through the inside of the wall portion 22.

[0028] Also, the cylindrical member 2 is a transparent member having permeability to visible light. Preferably, the visible light transmittance of the cylindrical member 2 is 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, or 90% or more. The visible light transmittance is specified as the average value of the transmittances at each wavelength when measured using a spectrophotometer at a measurement wavelength of 380 nm or more and 780 nm or less.

[0029] Such a cylindrical member 2 can be manufactured by molding a resin material. Examples of the resin material include PMMA (Polymethyl methacrylate). However, since the refractive index, strength, moisture resistance, etc. of the cylindrical member 2 vary depending on the resin material, it is not limited to PMMA, and it is preferable to appropriately select a material according to the usage conditions, usage environment, etc. of the lighting device. Also, the cylindrical member 2 can be configured to include a glass material. If it is transparent to visible light, a colored material may be used. The processing method is not limited to resin molding, and bending processing, cutting processing, etc. can also be applied.

[0030] As shown in FIG. 2B, the base portion 3 is provided with a groove portion 31 on the flat surface portion, and the LED 11 provided in the light source 1 is fixed to the bottom surface of the groove portion 31. Also, the base portion 3 fixes the cylindrical member 2 so as to close the opening portion of the groove portion 31 at the end portion of the wall portion 22 that intersects the cylindrical axis 20.

[0031] The cylindrical member 2 is provided at the bottom portion (the end portion on the negative Z-axis side) of the cylindrical member 2 facing the light source 1, and includes a light incident end surface 21 through which the light emitted from the light source 1 enters the inside of the wall portion 22. In FIGS. 1, 2A, and 2B, since the light source 1 is arranged facing the bottom portion of the cylindrical member 2, the light incident end surface 21 is included in the bottom portion of the cylindrical member 2. However, when the light source 1 is arranged facing the top portion (the end portion on the positive Z-axis side) of the cylindrical member 2, the light incident end surface 21 is included in the top portion of the cylindrical member 2.

[0032] Also, in FIGS. 1, 2A, and 2B, since the cylindrical axis 20 of the cylindrical member 2 is substantially parallel to the Z-axis, the bottom portion of the cylindrical member 2 is on the negative Z-axis side of the cylindrical member 2, and the top portion of the cylindrical member 2 is on the positive Z-axis side of the cylindrical member 2. However, when the cylindrical axis 20 of the cylindrical member 2 is substantially parallel to the X-axis, the bottom portion of the cylindrical member 2 exists on either the positive or negative X-axis side of the cylindrical member 2, and the top portion of the cylindrical member 2 exists on the other side of the positive or negative X-axis of the cylindrical member 2.

[0033] Alternatively, when the cylindrical axis 20 of the cylindrical member 2 is substantially parallel to the Y-axis, the bottom of the cylindrical member 2 is present on either the positive or negative side of the Y-axis in the cylindrical member 2, and the top of the cylindrical member 2 is present on the other side of the positive or negative side of the Y-axis in the cylindrical member 2. In other words, one end in the direction along the cylindrical axis 20 of the cylindrical member 2 corresponds to the bottom, and the other end corresponds to the top.

[0034] Further, the cylindrical member 2 has a light-emitting portion 231 that is included in the outer surface 23 of the cylindrical member 2 intersecting the light-incident end face 21 and from which light exits from inside the wall portion 22. Note that the outer surface 23 is the outer surface of the cylindrical member 2.

[0035] In FIGS. 2A and 2B, for ease of explanation, the light-emitting portion 231 is shown by a thick line, but the light-emitting portion 231 corresponds to the portion (region) on the outer surface 23 from which light exits and is not a member provided on the outer surface 23.

[0036] Further, the light guide portion 300 includes a light extraction portion 241 on the inner surface 24 which is the inner surface of the wall portion 22 in the cylindrical member 2. The light extraction portion 241 is a component having a function of emitting the light guided through the inside of the wall portion 22 from inside the wall portion 22.

[0037] In FIGS. 1, 2A, and 2B, the light emitted from each of the plurality of LEDs 11 enters the inside of the wall portion 22 through the light-incident end face 21 and is guided through the inside of the wall portion 22. Inside the wall portion 22, the light is guided while repeatedly undergoing total reflection at each of the outer surface 23 and the inner surface 24.

[0038] Thereafter, a part of the light guided through the inside of the wall portion 22 is reflected, scattered, refracted, or diffracted by the light extraction portion 241 toward the outside of the cylindrical member 2 and exits from inside the wall portion 22 toward the outside through the light-emitting portion 231.

[0039] The outgoing light 232 indicated by the dashed line in FIGS. 1, 2A, and 2B represents the light emitted from the inside of the wall portion 22 to the outside. As shown in FIGS. 1, 2A, and 2B, the outgoing light 232 is emitted in various directions such as the direction in which the outer surface 23 of the cylindrical member 2 faces from all over the outside of the cylindrical member 2. The lighting device 100 can illuminate a wide range of the space around the lighting device 100 with this outgoing light 232.

[0040] In addition, since the outgoing light 232 is also emitted in the vertical direction (Z-axis direction) in FIGS. 1, 2A, and 2B, the lighting device 100 can illuminate light not only in the 360-degree direction around the cylindrical axis 20 but also in the vertical direction (Z-axis direction). In other words, the lighting device 100 can illuminate light not only in the direction parallel to the flat surface portion of the base portion 3 but also in the direction intersecting the flat surface portion of the base portion 3.

[0041] Next, FIG. 3 is a view showing the base portion 3 and the light source 1 of the lighting device 100. The mounting surface 32 is a surface corresponding to one flat surface portion of the base portion 3, and is a surface where the end portion of the cylindrical member 2 abuts and the cylindrical member 2 is mounted. The groove portion 31 is a depression dug by a predetermined depth from the mounting surface 32 and is a portion formed in an annular shape. The LED 11 is fixed on the bottom surface of the groove portion 31. The cross-sectional shape of the groove of the groove portion 31 is not particularly limited, and may be rectangular or U-shaped, or may include irregularities inside the groove portion 31, but it is preferable to include a flat surface portion in order to stably fix the LED 11.

[0042] Here, the case where the light source 1 is the base portion 3 on the flat plate including the LED 11 is shown, but the form of the light source 1 is not limited to this. For example, it may be formed so as to cover the light incident end surface 21 of the cylindrical member 2, and an LED may be arranged in an annular housing for fixing the cylindrical member. For example, a groove portion is provided on the upper surface of the annular housing, and an LED is arranged at the bottom of the groove portion. The light incident end surface 21 of the cylindrical member 2 can be inserted into the groove portion to fix the cylindrical member 2 to the annular housing.

[0043] <Configuration Example of Light Extraction Port> Next, the configuration of the light extraction portion included in the light guide portion 300 will be described with reference to FIGS. 4A to 11B. FIGS. 4A to 6B and FIGS. 8A to 11B are partial enlarged views respectively illustrating the detailed configuration of the light extraction portion. FIG. 4A shows the first example, FIG. 4B shows the second example, FIG. 5A shows the third example, FIG. 5B shows the fourth example, FIG. 6A shows the fifth example, and FIG. 6B shows the sixth example. FIGS. 7A and 7B are diagrams showing an example of the configuration of the cylindrical member having the light extraction portion of FIG. 6A, FIG. 7A is a top view, and FIG. 7B is a cross-sectional view taken along the line B-B' of FIG. 7A.

[0044] Furthermore, FIG. 8A shows the seventh example of the detailed configuration of the light extraction portion, FIG. 8B shows the eighth example, FIG. 9A shows the ninth example, FIG. 9B shows the tenth example, FIG. 10A shows the eleventh example, FIG. 10B shows the twelfth example, FIG. 11A shows the thirteenth example, and FIG. 11B shows the fourteenth example.

[0045] First, the light extraction portion 241 included in the light guide portion 300 shown in FIG. 4A has an optical functional layer 243 that includes a light cavity 242 inside. The optical functional layer 243 is provided on the inner surface 24. Note that the optical functional layer refers to a layer that exhibits an optical function.

[0046] The optical functional layer 243 is a thin layer formed of a material such as resin and is laminated and provided on the surface of the cylindrical member 2. For example, a layered member including the optical functional layer 243 can be attached by an adhesive-free lamination method such as microwave surface treatment, or can be provided on the inner surface 24 by adhesion with an adhesive (including a pressure-sensitive adhesive). Further, the optical functional layer 243 is formed in a cylindrical shape along the shape of the inner surface 24.

[0047] Note that layers having other functions such as a cover layer may be included before and after the optical functional layer 243 in the stacking direction.

[0048] The material of the optical functional layer 243 and the material of the adhesive that adheres the optical functional layer 243 to the cylindrical member 2 are preferably those having a refractive index close to that of the cylindrical member 2 in order to suppress refraction and reflection of light at the interface with the cylindrical member 2. For example, it is suitable to use a material containing the same PMMA as the cylindrical member 2.

[0049] The optical cavity 242 is an example of the void portion and is filled with air inside. However, the optical cavity 242 may be filled with a material having a refractive index lower than that of the optical functional layer instead of air. A plurality of optical cavities 242 are provided regularly or randomly in the optical functional layer 243. The size of the optical cavity 242 can be appropriately selected within the range that can be installed inside the optical functional layer 243.

[0050] The optical functional layer containing the optical cavity inside is not particularly limited. For example, the optical functional layers disclosed in International Publication No. 2011 / 124765, International Publication No. 2011 / 127187, International Publication No. 2019 / 087118, and International Publication No. 2019 / 182091 can be used. These contents are incorporated herein by reference.

[0051] The optical functional layer 243 is produced, for example, by laminating a first film 2431 on which no pattern is formed and a second film 2432 on which a desired fine pattern is formed by a lamination method, or by adhering them with an adhesive (including a pressure-sensitive adhesive).

[0052] For forming the fine pattern on the second film 2432, laser patterning, direct laser imaging, laser drilling, laser or electron beam irradiation with or without a mask are used. Also, individual characteristics may be imparted by printing, inkjet printing, screen printing, etc. to change the material and refractive index value. Micro / nano dispensing, dosing, direct "writing", discrete laser sintering, micro electrical discharge machining (micro EDM), micromachining, microforming, imprinting, embossing, and the like can also be used.

[0053] The light guided inside the wall portion 22 of the cylindrical member 2 passes through the interface between the cylindrical member 2 and the optical function layer 243 or is refracted at the interface and enters the optical function layer 243. Then, a part of the light guided inside the optical function layer 243 is totally reflected at the interface between the optical function layer 243 and the optical cavity 242 and is guided toward the light emitting portion 231. Among this reflected light, the light incident on the outer surface 23 at an angle not exceeding the critical angle exits from the inside to the outside of the wall portion 22 of the cylindrical member 2. The portion where the light exits within the outer surface 23 corresponds to the light emitting portion 231.

[0054] The light not reflected at the interface between the optical function layer 243 and the optical cavity 242 is guided while repeating total reflection at the interface between the optical function layer 243 and the external air. A part of this light is reflected at the interface between the optical cavity 242 and the optical function layer 243 and exits from the inside to the outside of the wall portion 22 of the cylindrical member 2. The above-described reflection occurs at each of the plurality of optical cavities 242 provided in the optical function layer 243.

[0055] In this way, the light extraction portion 241 can emit light from the light emitting portion 231 within the outer surface 23. The angle of the interface between the optical function layer 243 and the optical cavity 242 is predetermined to be a suitable angle according to the use of the lighting device.

[0056] Next, the light extraction portion 241a included in the light guide portion 300a shown in FIG. 4B has an optical function layer 245 that contains light scattering particles 244 inside. The optical function layer 245 is provided on the inner surface 24. The material and installation method of the optical function layer 245 are the same as those of the optical function layer 243 described above.

[0057] The light-scattering particles 244 have a refractive index difference with respect to the material constituting the optical function layer 245 and are particles having an average particle diameter of about 0.3 to 5 μm. The light-scattering particles 244 are an example of a light-scattering body that scatters light guided within the wall portion 22. A plurality of light-scattering particles 244 are contained in the material constituting the optical function layer 245. The optical function layer containing light-scattering particles inside is not particularly limited, but for example, the optical function layer disclosed in JP-A-2013-195811 can be used. These contents are incorporated herein by reference. Here, the average particle diameter is the volume-average particle diameter and can be measured using, for example, an ultracentrifugal automatic particle size distribution measuring device.

[0058] The light guided within the wall portion 22 enters the optical function layer 245 by passing through or refracting at the interface between the cylindrical member 2 and the optical function layer 245. Then, a part of the light guided within the optical function layer 245 is scattered at the interface between the optical function layer 245 and the light-scattering particles 244 and is guided toward the light-emitting portion 231. Among this scattered light, the light incident on the outer surface 23 at an angle not exceeding the critical angle exits from the inside to the outside of the wall portion 22 in the cylindrical member 2. The portion where the light exits within the outer surface 23 corresponds to the light-emitting portion 231.

[0059] The light that is not scattered at the interface between the optical function layer 245 and the light-scattering particles 244 is guided while repeating total reflection at the interface between the optical function layer 245 and the external air. A part of this light is scattered at the interface between the light-scattering particles 244 and the optical function layer 245 and exits from the inside to the outside of the wall portion 22 in the cylindrical member 2. The above-described scattering occurs at each of the plurality of light-scattering particles 244 provided in the optical function layer 245.

[0060] In this way, the light extraction portion 241a can emit light from the light-emitting portion 231 within the outer surface 23.

[0061] Next, the light extraction part 241b of the light guide part 300b shown in FIG. 5A has an optical function layer 243 that includes a light cavity 242 inside. The optical function layer 243 is provided on the outer surface 23. The material and function of the optical function layer 243 are the same as those of the optical function layer 243 in the light extraction part 241. The portion where the optical function layer 243 is provided within the outer surface 23 corresponds to the light emitting part 231.

[0062] Also, the light extraction part 241c of the light guide part 300c shown in FIG. 5B has an optical function layer 245 that includes light scattering particles 244 inside. The optical function layer 245 is provided on the outer surface 23. The material and function of the optical function layer 245 are the same as those of the optical function layer 245 in the light extraction part 241a. The portion where the optical function layer 245 is provided within the outer surface 23 corresponds to the light emitting part 231.

[0063] Next, the light extraction part 241d of the light guide part 300d shown in FIG. 6A has a light cavity 246. The light cavity 246 is provided within the wall part 22d of the cylindrical member 2d.

[0064] The light cavity 246 is an example of a void part and is filled with air inside. However, instead of air, a material with a refractive index lower than that of the cylindrical member 2d may be filled in the light cavity 246. A plurality of light cavities 246 are provided regularly or randomly within the wall part 22d of the cylindrical member 2d. The size of the light cavity 246 can be appropriately selected within the range that can be installed within the wall part 22d of the cylindrical member 2d.

[0065] The manufacturing method of the cylindrical member 2d is not particularly limited. For example, a method of forming the second cylindrical member 202 by winding a film with a desired fine pattern around the outer surface of the first cylindrical member 201 may be used.

[0066] Alternatively, a method of forming the first cylindrical member 201 by winding a film without a pattern around the inner surface of the second cylindrical member 202 may be used. Alternatively, it may be manufactured by connecting one end of a plate-like member formed by bonding a first film without a pattern and a second film with a desired fine pattern formed thereon to the other end with an adhesive or the like. In this case, the first cylindrical member 201 is formed from the first film, and the second cylindrical member 202 is formed from the second film.

[0067] Note that the bonding between the members is performed by laminating the first film and the second film by a lamination method such as adhesive-free microwave surface treatment, or by using an adhesive (including a pressure-sensitive adhesive).

[0068] Alternatively, it may be manufactured by bonding the first cylindrical member 201 without a pattern and the second cylindrical member 202 with a desired fine pattern formed thereon by a lamination method such as adhesive-free microwave surface treatment, or by bonding with an adhesive (including a pressure-sensitive adhesive). In order to suppress interface reflection, it is preferable to make the refractive indices of the first cylindrical member 201 and the second cylindrical member 202 substantially equal, and when bonding with an adhesive, to make the refractive index of the adhesive substantially equal to those of the first cylindrical member 201 and the second cylindrical member 202.

[0069] For forming the fine pattern on the second cylindrical member 202, the same method as that for forming the fine pattern on the second film 2432 described above can be applied. Also, the function of the optical cavity 246 is the same as that of the optical cavity 242 described in FIGS. 4A and 5A.

[0070] Next, the light extraction portion 241e included in the light guide portion 300e shown in FIG. 6B has light scattering particles 247. The light scattering particles 247 are provided within the wall portion 22e of the cylindrical member 2e. The light scattering particles 247 have a refractive index difference with respect to the material constituting the cylindrical member 2e, are particles having an average particle diameter of about 0.3 to 5 μm, and are an example of a light scatterer that scatters the light guided within the wall portion 22e. The light scattering particles 247 are contained in the material constituting the cylindrical member 2e. The function of the light scattering particles 247 is the same as that of the light scattering particles 244 described in FIGS. 4B and 5B.

[0071] FIGS. 7A and 7B show an example of the configuration of the cylindrical member 2d having the light extraction portion 241d of FIG. 6A. As shown in FIGS. 7A and 7B, the cylindrical member 2d has a first cylindrical member 201 on which no pattern is formed and a second cylindrical member 202 on which a desired fine pattern is formed. A film on which a desired fine pattern is formed is wound around the outer surface of the first cylindrical member 201 to form the second cylindrical member 202.

[0072] Alternatively, the first cylindrical member 201 and the second cylindrical member 202 are bonded together by a lamination method such as an adhesive-free microwave surface treatment or are adhered by an adhesive. An optical cavity 246 is formed between the fine pattern in the second cylindrical member 202 and the surface of the first cylindrical member 201.

[0073] Next, the light extraction portion 241f included in the light guide portion 300f shown in FIG. 8A has an optical functional layer 249 including a prism portion 248 on its surface. The optical functional layer 249 is provided on the inner surface 24. The prism portion 248 is a portion including a fine inclined surface capable of deflecting light.

[0074] The optical functional layer 249 is preferably made of a material having a refractive index close to that of the cylindrical member 2 in order to suppress the refraction and reflection of light at the interface between the cylindrical member 2 and the light extraction portion 241f. For example, it can be configured to include the same PMMA as the cylindrical member 2. A plurality of prism portions 248 are provided regularly or randomly on the surface of the optical functional layer 249. The size and adjacent intervals of the prism portions 248 can be appropriately selected within the range that can be formed on the optical functional layer 249.

[0075] For forming the prism portions 248 on the optical functional layer 249, the same method as that for forming the fine pattern on the second film 2432 described above can be applied.

[0076] The light guided inside the wall portion 22 passes through the interface between the cylindrical member 2 and the optical functional layer 249 or is refracted at the interface and enters the interior of the optical functional layer 243. Then, it is guided inside the optical functional layer 249, reflected by the prism portions 248, and guided toward the light emission portion 231. Among this reflected light, the light that enters the outer surface 23 at an angle not exceeding the critical angle exits from the inside to the outside of the wall portion 22 in the cylindrical member 2. The portion where the light exits within the outer surface 23 corresponds to the light emission portion 231. The above-mentioned reflection is performed by the plurality of prism portions 248 provided on the optical functional layer 249.

[0077] In this way, the light extraction portion 241f can emit light from the light emission portion 231 inside the outer surface 23. Note that the angle of the inclined surface in the prism portion 248 is predetermined to be a suitable angle according to the use of the lighting device.

[0078] Next, the light extraction portion 241g included in the light guide portion 300g shown in FIG. 8B has an optical functional layer 251 having concavo-convex portions 250 on its surface. The optical functional layer 251 is provided on the inner surface 24. The material of the optical functional layer 251 is the same as that of the above-described optical functional layer 249. The concavo-convex portions 250 are portions where a plurality of concave or convex portions having a width and height of about 1 to 5 μm are formed. The concavo-convex portions 250 are randomly formed on the surface of the optical functional layer 251 and scatter the light guided inside the optical functional layer 251.

[0079] For forming the uneven portion 250 on the optical functional layer 251, the same method as that for forming the fine pattern on the second film 2432 described above can be applied. Also, since the uneven portion 250 may be a random rough surface, blast processing or the like can also be applied.

[0080] The light guided inside the wall portion 22 passes through or is refracted at the interface between the cylindrical member 2 and the optical functional layer 251 and enters the inside of the optical functional layer 251. Then, a part of the light guided inside the optical functional layer 251 is scattered at the interface between the optical functional layer 251 and the uneven portion 250 and is guided toward the light emitting portion 231. Among this scattered light, the light that enters the outer surface 23 at an angle not exceeding the critical angle exits from the inside of the cylindrical member 2 to the outside. The portion where the light exits within the outer surface 23 corresponds to the light emitting portion 231. The above scattering is performed at each of the plurality of uneven portions 250 provided in the optical functional layer 251.

[0081] In this way, the light extraction portion 241g can emit light from the light emitting portion 231 inside the outer surface 23.

[0082] Next, the light extraction portion 241h included in the light guide portion 300h shown in FIG. 9A has an optical functional layer 249 including a prism portion 248 on its surface. The optical functional layer 249 is provided on the outer surface 23. The material and function of the optical functional layer 249 are the same as those of the optical functional layer 249 in the light extraction portion 241f. However, in this case, more light is reflected by surfaces other than the inclined surface such as the surface 248' substantially parallel to the Y axis in the prism portion 248. Note that the portion where the optical functional layer 249 is provided inside the outer surface 23 corresponds to the light emitting portion 231.

[0083] Also, the light extraction portion 241i included in the light guide portion 300i shown in FIG. 9B has an optical functional layer 251 including an uneven portion 250 on its surface. The optical functional layer 251 is provided on the outer surface 23. The material and function of the optical functional layer 251 are the same as those of the optical functional layer 251 in the light extraction portion 241g. Note that the portion where the optical functional layer 251 is provided inside the outer surface 23 corresponds to the light emitting portion 231.

[0084] Next, the light extraction part 241j included in the light guide part 300j shown in FIG. 10A has a prism part 252. The prism part 252 is formed on at least a part of the inner surface 24. The prism part 252 is a part including a fine slope surface capable of deflecting light. A plurality of prism parts 252 are provided regularly or randomly on the surface of the inner surface 24. The size of the slope surface and the adjacent intervals in the prism part 252 can be appropriately selected within the range that can be formed on the inner surface 24. The light deflected by the prism part 252 passes through the light emitting part 231 and is emitted.

[0085] For forming the prism part 252 on the inner surface 24, the same method as that for forming the prism part 248 on the above-described optical functional layer 249 can be applied. Also, the function of the prism part 252 is the same as that of the prism part 248 described with reference to FIGS. 8A and 9A.

[0086] Also, the light extraction part 241k included in the light guide part 300k shown in FIG. 10B has a concavo-convex part 253. The concavo-convex part 253 is formed on at least a part of the inner surface 24. The concavo-convex part 253 is a part where a plurality of concave parts or convex parts having a width and height of about 1 to 5 μm are formed. The concavo-convex part 253 is formed randomly on the inner surface 24 and scatters the light guided inside the wall part 22. The light scattered by the concavo-convex part 253 passes through the light emitting part 231 and is emitted.

[0087] For forming the concavo-convex part 253 on the inner surface 24, the same method as that for forming the concavo-convex part 250 on the above-described optical functional layer 251 can be applied. Also, the function of the concavo-convex part 253 is the same as that of the concavo-convex part 250 described with reference to FIGS. 8B and 9B.

[0088] Next, the light extraction part 241m included in the light guide part 300m shown in FIG. 11A has a prism part 252. The prism part 252 is formed on at least a part of the outer surface 23. The prism part 252 is the same as the prism part 252 in the light extraction part 241j, but in this case, more light is reflected by surfaces other than the slope surface such as the surface 252' substantially parallel to the Y axis in the prism part 252. Note that the part where a plurality of prism parts 252 are formed within the outer surface 23 corresponds to the light emitting part 231.

[0089] In addition, the light extraction part 241n included in the light guide part 300n shown in FIG. 10B has the uneven part 253. The uneven part 253 is formed on at least a part of the outer surface 23. The uneven part 253 is the same as the uneven part 253 in the light extraction part 241k. Note that the part where a plurality of uneven parts 253 are formed within the outer surface 23 corresponds to the light emission part 231.

[0090] <Function and Effect of Lighting Device 100> Next, the function and effect of the lighting device 100 will be described.

[0091] Conventionally, lighting devices for illuminating spaces such as indoors have been known. In addition, a configuration having a light guide body having at least one light incident surface facing a light source and a light emission surface substantially orthogonal thereto, and a prism sheet disposed on the light emission surface of the light guide body has been disclosed.

[0092] However, in the conventional configuration, since a plate-like member is used as the light guide body, light cannot be illuminated in a direction other than the direction in which the flat portion of the plate-like member faces, or even if it can be illuminated, only a small amount of light can be illuminated compared to the illumination light in the direction in which the flat portion faces. Therefore, there is room for improvement in illuminating a wide range of spaces.

[0093] In this embodiment, the light guide part 300 included in the lighting device 100 has a cylindrical member 2 and a light extraction part 241 that emits light guided through the inside of the wall part 22 of the cylindrical member 2 from the inside of the wall part 22.

[0094] In addition, the cylindrical member 2 is provided at the bottom of the cylindrical member 2 facing the light source 1, and has a light incident end surface 21 where the light emitted from the light source 1 enters the inside of the wall part 22, and a light emission part 231 included in the outer surface 23 of the cylindrical member 2 that intersects the light incident end surface 21 and from which light exits from the inside of the wall part 22.

[0095] The light emitted from the light source 1 enters the inside of the wall portion 22 in the cylindrical member 2 through the light incident end face 21 and is guided inside the wall portion 22. A part of the guided light is reflected, scattered, refracted or diffracted by the light extraction portion 241 toward the outside of the cylindrical member 2, and exits from the inside of the wall portion 22 to the outside through the light emission portion 231.

[0096] With this configuration, the lighting device 100 can emit light in various directions such as the direction in which the outer surface 23 of the cylindrical member 2 faces from all around the cylindrical member 2 on the outside of the cylindrical member 2. Since the outer surface 23 of the cylindrical member 2 faces in all 360-degree azimuths around the cylindrical axis 20 of the cylindrical member 2, compared with the conventional case, it is possible to illuminate a wider range of space with light and provide a lighting device capable of illuminating a wide range of space.

[0097] In addition, since the lighting device 100 has a transparent and cylindrical appearance, it can exhibit excellent design properties. Furthermore, it is possible to illuminate a wide range of space in various azimuths without dead angles (spaces not illuminated by light).

[0098] Also, in the present embodiment, by suppressing the directivity of light by emitting light from a wide area in the light emission portion 231, specularly reflected light from an illuminated surface or the like can be suppressed, and glare can be suppressed. Thereby, it is possible to illuminate a wide range of space while suppressing glare.

[0099] Also, in the present embodiment, since the light guide portion 300 having transparency to visible light is used, the user can see through to the other side of the light guide portion. Thereby, a comfortable space can be provided without impairing the expansion of the space.

[0100] Here, the visible light transmittance of the light guide portion 300 including the cylindrical member 2, the light extraction portion 241, etc. is preferably 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, or 90% or more. The visible light transmittance is specified as the average value of the transmittances at each wavelength when measured using a spectrophotometer at a measurement wavelength of 380 nm or more and 780 nm or less.

[0101] Also, the divergence angle of the light emitted from the light emitting unit 231 can be made anisotropic. For example, it is possible to emit light from the light emitting unit 231 that has a large divergence angle in the X-axis direction and a small divergence angle in the Z-axis direction in FIG. 1.

[0102] <Modification Example of the First Embodiment> Here, in the above-described embodiment, a cylindrical member is exemplified as the cylindrical member 2, but it is not limited thereto. The cylindrical member 2 may be a cylindrical member having a polygonal cross section such as a quadrangle, a triangle, or a hexagon.

[0103] FIGS. 12A, 12B, and 12C are perspective views showing an example of the configuration of an illumination device according to a modification example of the first embodiment. FIG. 12A is a view showing a first modification example, FIG. 12B is a view showing a second modification example, and FIG. 12C is a view showing a third modification example.

[0104] As shown in FIG. 12A, the illumination device 100p has a light guide unit 300p. The light guide unit 300p has a cylindrical member 2p. The cylindrical member 2p is a cylindrical member having a quadrangular cross section. With this configuration, the illumination device 100p can illuminate a wider range of a space including four directions and the like in which each surface parallel to the central axis 20p of the cylindrical member 2p faces on the outside of the cylindrical member 2p.

[0105] Also, as shown in FIG. 12B, the illumination device 100q has a light guide unit 300q. The light guide unit 300q has a cylindrical member 2q. The cylindrical member 2q is a cylindrical member having a triangular cross section. With this configuration, the illumination device 100q can illuminate a wider range of a space including three directions and the like in which each surface parallel to the central axis 20q of the cylindrical member 2q faces on the outside of the cylindrical member 2q.

[0106] As shown in FIG. 12C, the lighting device 100r includes a light guide portion 300r. The light guide portion 300r includes a cylindrical member 2r. The cylindrical member 2r is a cylindrical member having a hexagonal cross section. With this configuration, the lighting device 100r can illuminate light in a wider range of a space including six directions or the like in which each surface parallel to the central axis 20r of the cylindrical member 2r faces on the outside of the cylindrical member 2r.

[0107] In this way, even with a quadrangle, a triangle, and a hexagon, the same effects as those of the lighting device 100 according to the first embodiment can be obtained. Note that, in addition to the above-described circular, quadrangular, triangular, and hexagonal shapes, various shapes can be applied to the cross section of the cylindrical member, and the same effects as those of the lighting device 100 can be obtained. Further, regardless of the shape of the cross section of the cylindrical member, the light extraction portions 241, 241a to 241n can all be applied. However, it is preferable that the optical function layer in the light extraction portion is formed in a shape along the shape of the outer surface or the inner surface of the cylindrical member.

[0108] [Second Embodiment] Next, the lighting device 100s according to the second embodiment will be described. Note that the same component parts as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and redundant descriptions will be omitted as appropriate. This also applies to each of the embodiments and modification examples described hereinafter.

[0109] In the present embodiment, a low refractive index layer having a refractive index lower than that of the cylindrical member is provided on at least a part of at least one of the outer surface and the inner surface of the cylindrical member that guides light. Thereby, light loss caused by light guided inside the wall portion of the cylindrical member leaking from the cylindrical member due to scratches, dirt, fingerprints, etc. of the cylindrical member is prevented, and the light utilization efficiency is improved. Note that the low refractive index layer may be provided by being formed on at least a part of at least one of the outer surface and the inner surface of the cylindrical member, or may be provided by being bonded to the cylindrical member via an adhesive (including a pressure-sensitive adhesive).

[0110] FIG. 13A and FIG. 13B are diagrams for explaining an example of the function of the low refractive index layer 34 in the lighting device 100s. FIG. 13A is a diagram showing the lighting device 100s having the low refractive index layer, and FIG. 13B is a diagram showing the lighting device 100X according to a comparative example having no low refractive index layer.

[0111] As shown in FIG. 13A, the lighting device 100s has a light guide part 300s. In the light guide part 300s, an optical functional layer 243, a low refractive index layer 34, and a cover layer 35 are laminated and formed in this order on the surface of the cylindrical member 2. Note that a layer having other functions may be included between the surface of the cylindrical member 2 and the low refractive index layer 34.

[0112] Also, the visible light transmittance of the light guide part 300s having the cylindrical member 2, the optical functional layer 243, the low refractive index layer 34, and the cover layer 35 is preferably 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, or 90% or more. The visible light transmittance is specified as the average value of the transmittances at each wavelength when measured using a spectrophotometer at a measurement wavelength of 380 nm or more and 780 nm or less.

[0113] The low refractive index layer 34 is a layer having a refractive index lower than that of the cylindrical member 2. When the cylindrical member 2 is mainly composed of PMMA, the refractive index n1 of the cylindrical member 2 is around 1.49. In comparison, the refractive index n2 of the low refractive index layer 34 is preferably 1.30 or less, and more preferably 1.20 or less. The low refractive index layer is not particularly limited, but for example, a low refractive index layer having voids disclosed in International Publication No. 2019 / 146628 can be used. This content is incorporated herein by reference.

[0114] When the light guided inside the wall part 22 of the cylindrical member 2 has an incident angle on the low refractive index layer 34 that is larger than the critical angle (when incident at a shallow angle), the total reflection condition is satisfied, and total reflection occurs at the interface between the wall part 22 and the low refractive index layer 34. Here, the critical angle θc is represented by the following formula. θc = θi = arcsin(n2 / n1) Note that θi is the incident angle (angle from the normal).

[0115] The cover layer 35 is for protecting the cylindrical member 2, and preferably has high transparency to visible light. It is formed of glass, plastic, etc., and may have an ultraviolet absorption effect. From the viewpoint of a protective layer, higher strength is better, but it may also be a thin and flexible layer.

[0116] Also, in the lighting device 100X shown in Fig. 13B, an optical function layer 243 and a cover layer 35 are laminated in this order on the surface of the cylindrical member 2 included in the light guide part 300X, and it does not have a low refractive index layer. In this case, if foreign matters C such as scratches, dirt, fingerprints, sweat, and dust adhere to the surface of the cover layer 35, among the light guided inside the wall part 22, the light heading toward the cover layer 35 side is scattered by the foreign matters C and may leak outside from inside the wall part 22, resulting in light loss.

[0117] On the other hand, in the lighting device 100s, since a low refractive index layer 34 is provided between the cover layer 35 and the cylindrical member 2, the light guided inside the wall part 22 is totally reflected by the low refractive index layer 34 before reaching the cover layer 35 as shown in Fig. 13A. Thereby, it is possible to prevent the light guided inside the wall part 22 from reaching the foreign matters C, prevent light loss caused by scratches, dirt, fingerprints, etc., and improve the utilization efficiency of light.

[0118] Note that other effects are the same as those described in the first embodiment.

[0119] Also, the above effects can be obtained by providing the low refractive index layer 34 on at least a part of at least one of the outer surface or the inner surface of the cylindrical member 2. Further, the above effects can also be obtained by providing the low refractive index layer 34 in a region where the optical function layer 243 is not provided on at least one of the outer surface or the inner surface.

[0120] In FIGS. 13A and 13B, the configuration in which the low refractive index layer 34 is provided on the optical functional layer 243 including the optical cavity 242 is illustrated, but the present invention is not limited thereto. The low refractive index layer 34 can be provided on the optical functional layers 245, 249 or 251 including light scattering particles, and the low refractive index layer 34 can also be provided on the prism portion 252 or the concavo-convex portion 253.

[0121] [Third Embodiment] Next, with reference to FIGS. 14A and 14B, the lighting device 100t according to the third embodiment will be described. FIGS. 14A and 14B are diagrams for explaining an example of the configuration of the lighting device 100t, FIG. 14A is a top view, and FIG. 14B is a cross-sectional view taken along the line C-C' of FIG. 14A.

[0122] As shown in FIGS. 14A and 14B, the lighting device 100t has a light guide portion 300t. The light guide portion 300t also has a lid member 4. The lid member 4 is a member disposed on the end face 25 on the side opposite to the light incident end face 21 in the cylindrical member 2. The lid member 4 is a disc-shaped member having a diameter substantially equal to the diameter of the cylinder of the cylindrical member 2.

[0123] In FIGS. 14A and 14B, for the purpose of exemplifying the arrangement in which the cylinder axis 20 of the cylindrical member 2 is parallel to the Z axis and the light incident end face 21 is on the negative Z axis side, the arrangement position of the lid member 4 is on the positive Z axis side of the wall portion 22 in the cylindrical member 2, but the arrangement position of the lid member 4 is not limited thereto. For example, in the case of an arrangement in which the cylinder axis 20 of the cylindrical member 2 is parallel to the Z axis and the light incident end face 21 is on the positive Z axis side, the arrangement position of the lid member 4 is on the negative Z axis side of the wall portion 22. Further, when the cylinder axis 20 of the cylindrical member 2 is parallel to the X axis or the Y axis, the arrangement position of the lid member 4 corresponds to either the positive X axis side or the negative X axis side of the wall portion 22, or either the positive Y axis side or the negative Y axis side of the wall portion 22.

[0124] Such a lid member 4 is configured to include a material such as resin, glass, or metal. The material of the lid member 4 may be the same as or different from the material of the cylindrical member 2. However, in order to be unified with the transparent cylindrical member 2, it is preferably made of a transparent material.

[0125] In addition, in FIGS. 14A and 14B, the configuration in which the lid member 4 is a disk-shaped member having a diameter substantially equal to the diameter of the cylinder of the cylindrical member 2 is illustrated, but the present invention is not limited thereto. The lid member 4 may have a diameter larger than the diameter of the cylinder of the cylindrical member 2, or may have a shape other than a circular shape such as a rectangle. Further, the member is not limited to a plate-shaped member, and may be a member having a hemispherical shape or the like.

[0126] Furthermore, in FIGS. 14A and 14B, the configuration in which the lid member 4 is placed on the end face 25 of the cylindrical member 2 is illustrated, but the present invention is not limited thereto. The lid member may be arranged so as to cover the end of the cylindrical member 2 on the side opposite to the light incident end face 21.

[0127] The lid member 4 may be fixed to the cylindrical member 2 by adhesion or the like, or may be fixed by fitting when the lid member 4 covers the end of the cylindrical member 2. Alternatively, the lid member 4 may be configured not to be fixed only by being placed on the end face 25.

[0128] Further, the lid member 4 may be configured such that the light guided inside the wall portion 22 is further guided into the lid member 4 via the joint surface between the wall portion 22 and the lid member 4. In this case, the lid member 4 may include a light extraction portion as described in the first embodiment in order to emit the light guided inside the lid member 4 to the outside.

[0129] By providing the lid member 4 in this way, for example, it is possible to prevent dust and dirt from entering the inside of the cylindrical member 2 and to improve the appearance.

[0130] Note that other effects are the same as those described in the first embodiment. Further, the second embodiment can be applied to the third embodiment to obtain the same effects as the second embodiment.

[0131] [Fourth Embodiment] Next, with reference to FIGS. 15A and 15B, the lighting device 100u according to the fourth embodiment will be described. FIGS. 15A and 15B are diagrams for explaining an example of the configuration of the lighting device 100u, FIG. 15A is a top view, and FIG. 15B is a cross-sectional view taken along the line D-D' of FIG. 15A. As shown in FIGS. 15A and 15B, the lighting device 100u has a light guide part 300u. The light guide part 300u has a cylindrical member 2u.

[0132] The cylindrical member 2u is formed in a tapered shape that becomes thinner as it moves away from the light incident end face 21u. The direction of moving away from the light incident end face 21u corresponds to the positive Z-axis direction in the examples of FIGS. 15A and 15B. A light extraction part 241u is provided on the inner surface 24u of the cylindrical member 2u. The light extraction part 241u may be provided by forming a prism part or an uneven part on at least a part of the inner surface 24u, or may be provided by bonding an optical function layer to the cylindrical member 2u via an adhesive (including a pressure-sensitive adhesive).

[0133] The light extraction part 241u can reflect, scatter, refract, or diffract the light guided inside the wall part 22u of the cylindrical member 2u toward the outer surface 23u, and emit it from the inside of the wall part 22u to the outside through the light emission part 231u.

[0134] In this way, even in a configuration including the cylindrical member 2u formed in a tapered shape that becomes thinner as it moves away from the light incident end face 21u, the same effects as those of the first embodiment can be obtained. Note that other effects are the same as those described in the first embodiment.

[0135] In addition, although the configuration in which the cross section of the cylindrical member 2u is substantially circular is illustrated, a cylindrical member having a shape other than a substantially circular shape such as a triangle, a quadrilateral, or a hexagon may be used. Also, by applying the second and third embodiments to the lighting device 100u, the same effects as those of the second and third embodiments can be obtained. Further, not only the light extraction part 241 but also the light extraction parts 241a to 241n can be applied to the lighting device 100u. However, it is preferable that the optical function layer in the light extraction part is formed in a shape along the shape of the outer surface 23u or the inner surface 24u of the cylindrical member 2u.

[0136] <First Modification Example of the Fourth Embodiment> Next, FIGS. 16A and 16B are diagrams for explaining an example of the configuration of a lighting device 100v according to the first modification example of the fourth embodiment. FIG. 16A is a top view, and FIG. 16B is a cross-sectional view taken along the line E-E' of FIG. 16A. As shown in FIGS. 16A and 16B, the lighting device 100v has a light guide portion 300v. The light guide portion 300v also has a cylindrical member 2v.

[0137] The cylindrical member 2v is formed in a tapered shape that becomes thinner as it approaches the light incident end face 21v. The direction approaching the light incident end face 21v corresponds to the negative Z-axis direction in the examples of FIGS. 16A and 16B. A light extraction portion 241v is provided on the inner surface 24v of the cylindrical member 2v. The light extraction portion 241v may be provided by forming a prism portion, an uneven portion, or the like on at least a part of the inner surface 24v, or may be provided by bonding an optical functional layer to the cylindrical member 2v via an adhesive (including a pressure-sensitive adhesive).

[0138] The light extraction portion 241v can reflect, scatter, refract, or diffract the light guided inside the wall portion 22v of the cylindrical member 2v toward the outer surface 23v, and emit the light from the inside of the wall portion 22v to the outside through the light emission portion 231v.

[0139] Except for the fact that the tapered shape of the cylindrical member 2v becomes thinner as it approaches the light incident end face 21v, the lighting device 100v is the same as the lighting device 100u, so duplicate explanations are omitted here.

[0140] <Second Modification Example of the Fourth Embodiment> Next, FIGS. 17A and 17B are diagrams for explaining an example of the configuration of a lighting device 100w according to the second modification example of the fourth embodiment. FIG. 17A is a top view, and FIG. 17B is a cross-sectional view taken along the line F-F' of FIG. 17A. As shown in FIGS. 17A and 17B, the lighting device 100w has a light guide portion 300w. The light guide portion 300w also has a cylindrical member 2w.

[0141] The cylindrical member 2w has a conical shape with a tapered tip portion 26 that becomes thinner as it moves away from the light incident end face 21w. The tip portion 26 surrounded by a two-dot chain line circle in Fig. 17B corresponds to the tapered tip portion. A light extraction portion 241w is provided on the inner surface 24w of the cylindrical member 2w. Note that the light extraction portion 241w may be provided by forming a prism portion, an uneven portion, or the like on at least a part of the inner surface 24w, or may be provided by bonding an optical functional layer to the cylindrical member 2w via an adhesive (including a pressure-sensitive adhesive).

[0142] The light extraction portion 241w can reflect, scatter, refract, or diffract the light guided inside the wall portion 22w of the cylindrical member 2w toward the outer surface 23w, and emit the light from the inside of the wall portion 22w to the outside through the light emission portion 231w.

[0143] Except for the point that it has a conical shape with the tapered tip portion 26 connected, the lighting device 100w is the same as the lighting device 100u, so overlapping explanations are omitted. However, since the tapered tip portion 26 is connected in the lighting device 100w, it is possible to prevent dust and dirt from entering the inside of the cylindrical member 2w without providing the lid member 4 and the like shown in Figs. 14A and 14B.

[0144] In addition, in Figs. 17A and 17B, a configuration in which the cylindrical member 2w has a conical shape is illustrated, but the present invention is not limited thereto, and the cylindrical member 2w may have various pyramid-shaped shapes such as a triangular pyramid, a quadrangular pyramid, or a hexagonal pyramid. Further, since the cylindrical member 2w has a pyramid-shaped shape, it can also be referred to as a pyramid-shaped member.

[0145] [Fifth Embodiment] Next, with reference to Figs. 18, 19A, and 19B, the lighting device 100y according to the fifth embodiment will be described. Fig. 18 is a perspective view for explaining an example of the configuration of the lighting device 100y. Figs. 19A and 19B are diagrams for explaining an example of the configuration of the lighting device 100y, Fig. 19A is a top view, and Fig. 19B is a cross-sectional view taken along the line G-G' of Fig. 19A.

[0146] As shown in FIGS. 18, 19A, and 19B, the lighting device 100y has a light guide unit 300y. The light guide unit 300y has a cylindrical member 2y. However, unlike the cylindrical member 2, the ends of the plate-like member are not connected to each other. The cylindrical member 2y is a member formed by winding a plate-like member into a cylinder. As the material of the cylindrical member 2y, the same material as that of the cylindrical member 2 can be applied.

[0147] Also, as shown in FIGS. 19A and 19B, a light extraction unit 241y is provided on the inner surface 24y of the cylindrical member 2y. The light extraction unit 241y may be provided by forming a prism unit, an uneven portion, or the like on at least a part of the inner surface 24y, or may be provided by bonding an optical functional layer to the cylindrical member 2y via an adhesive (including a pressure-sensitive adhesive).

[0148] The light extraction unit 241y can reflect, scatter, refract, or diffract the light guided inside the wall portion 22y of the cylindrical member 2y toward the outer surface 23y, and emit the light from the inside of the wall portion 22y to the outside through the light emission unit 231y.

[0149] Thus, even in a configuration including the cylindrical member 2y formed by winding a plate-like member into a cylinder, the same effects as those of the first embodiment can be obtained. In other words, the cylindrical member may have a configuration in which the ends of the plate-like member are not connected to each other, or a configuration in which a part of the cylinder along the circumferential direction is missing, and the same effects as those of the first embodiment can be obtained with these configurations.

[0150] In addition, other effects are the same as those described in the first embodiment.

[0151] In addition, although a configuration in which the cross-section of the cylindrical member 2y is substantially circular has been illustrated, the cylindrical member may have a shape other than a substantially circular shape such as a triangle, a quadrilateral, or a hexagon. Note that the cylindrical member 2y shown in FIGS. 18, 19A, and 19B is formed such that a part of the outer surface is in contact with a part of the inner surface, but the present invention is not limited to this form, and a part of the outer surface may be formed without being in contact with a part of the inner surface.

[0152] Moreover, each of the second to fourth embodiments can be applied to the lighting device 100y to obtain the same effects as those of the second to fourth embodiments. In addition to the light extraction part 241, any of the light extraction parts 241a to 241n can be applied to the lighting device 100y. However, it is preferable that the optical functional layer in the light extraction part is formed in a shape along the shape of the outer surface or the inner surface of the cylindrical member 2y.

[0153] [Sixth Embodiment] Next, with reference to FIGS. 20, 21A, and 21B, the lighting device 100z according to the sixth embodiment will be described. FIG. 20 is a perspective view for explaining an example of the configuration of the lighting device 100z. FIGS. 21A and 21B are views for explaining an example of the configuration of the lighting device 100z, FIG. 21A is a top view, and FIG. 21B is a cross-sectional view taken along the line H-H' of FIG. 21A.

[0154] As shown in FIGS. 20, 21A, and 21B, the lighting device 100z includes a light guide part 300z. The light guide part 300z includes a curved surface member 2z. The curved surface member 2z is a hollow hemispherical member. In other words, the curved surface member 2z is a hollow hemispherical body that is a part of a hollow sphere. The material of the curved surface member 2z can be the same as that of the cylindrical member 2.

[0155] The curved surface member 2z and the installation surface 3z of the curved surface member 2z on the base part 3 form a sealed space. The installation surface 3z is the surface on the positive Z-axis side of the base part 3 and is an example of the installation surface of the curved surface member. Here, the sealed space refers to a space in which the entire space formed by the curved surface member 2z and the installation surface 3z is closed and not open to the outside.

[0156] The manufacturing method of the spherical surface member is not particularly limited. For example, it can be manufactured by pressing a mold of a desired shape against a plate-like member and processing the plate-like member.

[0157] Also, as shown in FIGS. 21A and 21B, a light extraction portion 241z is provided on the inner surface 24z of the curved surface member 2z. The inner surface 24z corresponds to the entire inner surface of the curved surface member 2z, and the outer surface 23z corresponds to the entire outer surface of the curved surface member 2z.

[0158] Also, the light extraction portion 241z may be provided by forming a prism portion, an uneven portion, or the like on at least a part of the inner surface 24z, or may be provided by bonding an optical functional layer to the curved surface member 2z via an adhesive (including a pressure-sensitive adhesive).

[0159] As shown in FIG. 21B, the light emitted from the light source 1 enters the inside of the wall portion 22z through the light incident end surface 21z of the curved surface member 2z and is guided inside the wall portion 22z. Inside the wall portion 22z, the light is guided while repeating total reflection on the outer surface 23z and the inner surface 24z respectively.

[0160] The light extraction portion 241z can reflect, scatter, refract, or diffract a part of the light guided inside the wall portion 22z toward the outer surface 23z, and emit it from the inside of the wall portion 22z to the outside through the light emission portion 231z.

[0161] Thus, even in a configuration including the curved surface member 2z which is a hemispherical member, the same effects as those of the first embodiment can be obtained. Also, by making it hemispherical, light with substantially uniform brightness can be used to illuminate a wide range of the space. Also, since the inside of the curved surface member 2z is not open to the outside, it is possible to prevent dust and dirt from entering the inside of the curved surface member 2z without providing the lid member 4 or the like shown in FIGS. 14A and 14B. Other effects are the same as those described in the first embodiment.

[0162] Also, when the second embodiment is applied to the lighting device 100z, the same effects as those of the second embodiment can also be obtained. Also, not only the light extraction portion 241 but also the light extraction portions 241a to 241n can all be applied to the lighting device 100z. However, it is preferable that the optical functional layer in the light extraction portion 241z is formed in a shape along the shape of the outer surface 23z or the inner surface 24z of the curved surface member 2z.

[0163] <Modification Example of the Sixth Embodiment> Here, the curved surface member included in the lighting device according to the embodiment is not limited to a hemispherical member, and any member that is a part of a hollow sphere or a part of a rotating ellipsoid may be used. Hereinafter, various modification examples of the lighting device having a curved surface member will be described.

[0164] (First and Second Modification Examples) FIGS. 22A and 22B are perspective views for explaining the configuration of a lighting device according to a modification example of the sixth embodiment, where FIG. 22A shows a first modification example and FIG. 22B shows a second modification example.

[0165] As shown in FIG. 22A, the lighting device 100A includes a light guide unit 300A. The light guide unit 300A includes a curved surface member 2A. The curved surface member 2A is a part of a hollow rotating ellipsoid obtained by rotating an ellipse having the X-axis as its major axis around the X-axis.

[0166] Also, as shown in FIG. 22B, the lighting device 100B includes a light guide unit 300B. The light guide unit 300B includes a curved surface member 2B. The curved surface member 2B is a part of a hollow rotating ellipsoid obtained by rotating an ellipse having the Z-axis as its major axis around the Z-axis.

[0167] The lighting device 100A is the same as the lighting device 100z except that the curved surface member 2A is a part of a hollow rotating ellipsoid obtained by rotating an ellipse having the X-axis as its major axis around the X-axis. Also, the lighting device 100B is the same as the lighting device 100z except that the curved surface member 2B is a part of a hollow rotating ellipsoid obtained by rotating an ellipse having the Z-axis as its major axis around the Z-axis. Therefore, overlapping explanations are omitted here.

[0168] (Third Modification Example) Next, FIGS. 23A and 23B are diagrams for explaining an example of the configuration of a lighting device 100D according to a third modification example of the sixth embodiment, where FIG. 23A is a top view and FIG. 23B is a cross-sectional view taken along the line I-I' of FIG. 23A.

[0169] As shown in FIGS. 23A and 23B, the lighting device 100D includes a light guide part 300D. The light guide part 300D includes a curved surface member 2D. The curved surface member 2D corresponds to a portion corresponding to approximately 1 / 4 of a hollow sphere.

[0170] A light extraction part 241D is provided on the inner surface 24D of the curved surface member 2D. The inner surface 24D corresponds to the entire inner surface of the curved surface member 2D, and the outer surface 23D corresponds to the entire outer surface of the curved surface member 2D.

[0171] The light extraction part 241D may be provided by forming a prism part, an uneven part, or the like on at least a part of the inner surface 24D, or may be provided by bonding an optical functional layer to the curved surface member 2D via an adhesive (including a pressure-sensitive adhesive).

[0172] The light emitted from the light source 1 enters the inside of the wall part 22D through the light incident end face 21D of the curved surface member 2D and is guided inside the wall part 22D. Inside the wall part 22D, the light is guided while repeatedly undergoing total reflection at the outer surface 23D and the inner surface 24D respectively.

[0173] The light extraction part 241D can reflect, scatter, refract, or diffract a part of the light guided inside the wall part 22D of the curved surface member 2D toward the outer surface 23D, and emit it from the inside of the wall part 22D to the outside through the light emission part 231D.

[0174] Thus, even in a configuration including the curved surface member 2D that corresponds to a portion corresponding to approximately 1 / 4 of a hollow sphere, the same effects as those of the lighting device 100z according to the sixth embodiment can be obtained. However, in the configuration of FIGS. 23A and 23B, since the lighting device 100D cannot illuminate light in the positive X-axis direction, the illumination range is narrower compared to the lighting device 100z, but still, light can be illuminated in a wide range of a space corresponding to 180 degrees of azimuth.

[0175] Note that the second embodiment can also be applied to the lighting device 100D to obtain the same effects as those of the second embodiment. In addition to the light extraction part 241, any of the light extraction parts 241a to 241n can also be applied to the lighting device 100D. However, it is preferable that the optical functional layer in the light extraction part 241D is formed in a shape along the shape of the outer surface 23D or the inner surface 24D of the curved surface member 2D.

[0176] (Fourth Modification Example) Next, FIGS. 24A and 24B are diagrams for explaining an example of the configuration of a lighting device 100E according to a fourth modification example of the sixth embodiment. FIG. 24A is a top view, and FIG. 24B is a cross-sectional view taken along the line J-J' of FIG. 24A.

[0177] As shown in FIGS. 24A and 24B, the lighting device 100E includes a light guide part 300E. The light guide part 300E also includes a curved surface member 2E. The curved surface member 2E is a part corresponding to more than half of a hollow sphere.

[0178] A light extraction part 241E is provided on the inner surface 24E of the curved surface member 2E. The inner surface 24E corresponds to the entire inner surface of the curved surface member 2E, and the outer surface 23E corresponds to the entire outer surface of the curved surface member 2E.

[0179] The light extraction part 241E may be provided by forming a prism part, an uneven part, or the like on at least a part of the inner surface 24E, or may be provided by bonding an optical functional layer to the curved surface member 2E via an adhesive (including a pressure-sensitive adhesive).

[0180] The light emitted from the light source 1 enters the inside of the wall part 22E through the light incident end face 21E in the curved surface member 2E and is guided inside the wall part 22E. Inside the wall part 22E, the light is guided while repeatedly undergoing total reflection on each of the outer surface 23E and the inner surface 24E.

[0181] The light extraction part 241E can reflect, scatter, refract, or diffract the light guided inside the wall part 22E in the curved surface member 2E toward the outer surface 23E, and emit the light from the inside of the wall part 22E to the outside through the light emission part 231E.

[0182] Thus, even in a configuration including the curved surface member 2E that corresponds to more than half of the hollow sphere, the same effects as those of the lighting device 100z according to the sixth embodiment can be obtained. Note that the second embodiment can be applied to the lighting device 100D to obtain the same effects as those of the second embodiment. Further, not only the light extraction portion 241 but also the light extraction portions 241a to 241n can all be applied to the lighting device 100E. However, it is preferable that the optical function layer in the light extraction portion 241E is formed in a shape following the shape of the outer surface 23E or the inner surface 24E of the curved surface member 2E.

[0183] [Seventh Embodiment] Next, with reference to FIG. 25, the lighting device 100F according to the seventh embodiment will be described. The lighting device 100F is a device that is installed on a side wall or the like inside a building and illuminates the indoor space from the side wall.

[0184] FIG. 25 is a cross-sectional view for explaining an example of the configuration of the lighting device 100F. FIG. 25 corresponds to a view obtained by rotating the configuration of FIG. 2B, which is a cross-sectional view taken along the line A-A' of FIG. 2A, 90 degrees clockwise.

[0185] As shown in FIG. 25, the lighting device 100F has the same components as the lighting device 100 shown in the first embodiment. In the lighting device 100F, each component included in the lighting device 100 is rotated 90 degrees clockwise as a whole, and the base portion 3 including the light source 1 is fixed to the side wall 301.

[0186] The light emitted from the light source 1 enters the wall portion 22 in the cylindrical member 2 through the light incident end face 21, and is guided through the wall portion 22 while repeating total reflection at the outer surface 23 and the inner surface 24.

[0187] A part of the light guided through the inside of the wall portion 22 is reflected, scattered, refracted, or diffracted by the light extraction portion 241 toward the outside of the cylindrical member 2, and is emitted from the inside of the wall portion 22 to the outside through the light emission portion 231.

[0188] The lighting device 100F fixed to the side wall 301 can illuminate a wide range of the indoor space with the emitted light 232 emitted from the light emitting portion 231. Note that the installation location of the lighting device 100F is not limited to the side wall inside the building, and the lighting device 100F may be installed on the side wall outside the building. Also, the base portion 3 may be embedded inside the side wall 301 so that the lighting device 100F is fixed to the side wall 301.

[0189] In addition, in the present embodiment, the configuration in which the lighting device 100F has the light guide portion 300 is illustrated, but the present invention is not limited thereto. Instead of the light guide portion 300, the lighting device 100F may have any one of the light guide portions 300a to 300E.

[0190] [Eighth Embodiment] Next, with reference to FIG. 26, the lighting device 100G according to the eighth embodiment will be described. The lighting device 100G is a device that is installed on the ceiling or the like inside a building and illuminates the indoor space from the ceiling.

[0191] FIG. 26 is a cross-sectional view for explaining an example of the configuration of the lighting device 100G. FIG. 26 corresponds to a view obtained by rotating the configuration of FIG. 2B, which is a cross-sectional view taken along the line A-A' of FIG. 2A, 180 degrees clockwise.

[0192] As shown in FIG. 26, the lighting device 100G has the same components as the lighting device 100 shown in the first embodiment. In the lighting device 100G, each component included in the lighting device 100 is arranged by being rotated 180 degrees clockwise as a whole, and the base portion 3 including the light source 1 is fixed to the ceiling 302.

[0193] The light emitted from the light source 1 enters the wall portion 22 in the cylindrical member 2 through the light incident end face 21, and is guided through the wall portion 22 while repeatedly undergoing total reflection on the outer surface 23 and the inner surface 24.

[0194] A part of the light guided through the inside of the wall portion 22 is reflected, scattered, refracted, or diffracted by the light extraction portion 241 toward the outside of the cylindrical member 2, and is emitted from the inside of the wall portion 22 to the outside through the light emitting portion 231.

[0195] The lighting device 100G fixed to the ceiling 302 can illuminate a wide range of the indoor space with the emitted light 232 emitted from the light emitting portion 231. Incidentally, the lighting device 100G may be fixed to the ceiling 302 in such a manner that the base portion 3 is embedded inside the ceiling 302.

[0196] In addition, in the present embodiment, the configuration in which the lighting device 100G has the light guide portion 300 is illustrated, but the present invention is not limited thereto. Instead of the light guide portion 300, the lighting device 100G may have any one of the light guide portions 300a to 300E.

[0197] As described above, the preferred embodiments of the present invention have been described in detail. However, 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 present invention.

[0198] Incidentally, the curved surface member according to the embodiment may have any shape as long as it is a part of a hollow sphere or an ellipsoid of revolution. However, if the curved surface member and the installation surface are configured to form a sealed space, it is possible to prevent dust and dirt from entering the sealed space, which is more preferable.

[0199] This application claims priority based on Japanese Patent Application No. 2020-194606 filed with the Japan Patent Office on November 24, 2020, and includes all the contents of this Japanese patent application.

Explanation of reference numerals

[0200] 1 Light source 11 LED 12 Drive circuit 2, 2d, 2e, 2p, 2q, 2r, 2u, 2v, 2w, 2y Cylindrical member 2z, 2A, 2B, 2D, 2E Curved surface member 20 Cylindrical axis 20p, 20q, 20r Central axis 201 First cylindrical member 202 Second cylindrical member 21, 21u, 21v, 21w, 21y, 21z, 21D, 21E Light incident end faces 22, 22u, 22v, 22w, 22y, 22z, 22D, 22E Wall parts 23, 23u, 23v, 23w, 23y, 23z, 23D, 23E Outer surfaces 231, 231u, 231v, 231w, 231y, 231z, 231D, 231E Light emitting parts 232 Emitted light 24, 24u, 24v, 24w, 24y, 24z, 24D, 24E Inner surfaces 241, 241u, 241v, 241w, 241y, 241z, 241D, 241E Light extraction parts 232 Emitted light 242, 246 Light cavity (an example of a void part) 243, 245, 249, 251 Optical functional layers 2431 First film 2432 Second film 244, 247 Light scattering particles (an example of a light scatterer) 248, 252 Prism parts 250, 253 Concavo-convex parts 25 End face 26 Tip part 3 Base part 3z Installation surface 31 Groove part 32 Mounting surface 34 Low refractive index layer 35 Cover layer 4 Cover member 100, 100p, 100q, 100r, 100s, 100t, 100u, 100v, 100w, 100y, 100z, 100A, 100B, 100D, 100E, 100F, 100G Lighting device 300, 300a, 300b, 300c, 300d, 300e, 300f, 300g, 300h, 300i, 300j, 300k, 300m, 300n, 300p, 300q, 300r, 300s, 300t, 300u, 300v, 300w, 300y, 300z, 300A, 300B, 300D, 300E Light guide part 301 Side wall 302 Ceiling X X-axis direction (width direction) Y Y-axis direction (depth direction) Z Z-axis direction (height direction)

Claims

1. A light source, and a light guide unit that guides the light emitted from the light source, wherein the light guide unit includes a cylindrical member, and a light extraction unit that extracts the light guided through the inside of the wall portion of the cylindrical member to the outside of the wall portion, wherein the cylindrical member is provided on either the bottom or the top of the cylindrical member facing the light source, and has a light incident end face through which the light enters the inside of the wall portion, and includes a light emission portion that is included in the outer surface of the cylindrical member intersecting the light incident end face and through which the light exits from the inside of the wall portion, wherein the cylindrical member has translucency with respect to visible light, and a lighting device in which the back of the cylindrical member can be seen through.

2. The lighting device according to claim 1, wherein the cylindrical member is a cylindrical member.

3. The lighting device according to claim 1 or 2, wherein the cylindrical member is a member formed by winding a plate-like member into a cylindrical shape.

4. The lighting device according to any one of claims 1 to 3, wherein the cylindrical member is formed in either a tapered shape that becomes thinner as it moves away from the light incident end face or a tapered shape that becomes thinner as it approaches the light incident end face.

5. The light guide unit includes the cylindrical member, and a lid member disposed on an end face of the cylindrical member opposite to the light incident end face,

6. The lighting device according to claim 4, wherein the cylindrical member has a conical shape in which the tip portions of a tapered shape that becomes thinner as it moves away from the light incident end face are connected.

7. The light guide unit has a low refractive index layer having a lower refractive index than the cylindrical member, and the low refractive index layer is provided on at least a part of at least one of the inner surface or the outer surface of the cylindrical member intersecting the light incident end face,

8. The light extraction unit has an optical function layer that includes at least one of a void portion or a light scattering body inside, and the optical function layer is provided on at least a part of at least one of the inner surface or the outer surface of the cylindrical member intersecting the light incident end face,

9. The light extraction unit has an optical function layer that includes at least one of a prism portion or an uneven portion on the surface, and the optical function layer is provided on at least a part of at least one of the inner surface or the outer surface of the cylindrical member intersecting the light incident end face,

10. The lighting device according to any one of claims 1 to 7, wherein the light extraction unit has at least one of a prism unit and an uneven unit provided on at least a part of at least one of the inner surface and the outer surface of the cylindrical member intersecting the light incident end face.

11. A light source, a light guide unit that guides the light emitted from the light source, and has, The light guide unit a curved surface member that is a part of a hollow sphere or an ellipsoid of revolution, a light extraction unit that emits the light guided through the inside of the wall portion of the curved surface member from the inside of the wall portion, and has, The curved surface member a light incident end face provided at the bottom of the curved surface member facing the light source, where the light enters the inside of the wall portion, a light emission part that is included in the outer surface of the curved surface member intersecting the light incident end face, and the light is emitted from the inside of the wall portion, and has, The curved surface member has translucency with respect to visible light, A lighting device in which the back of the curved surface member can be seen through.

12. The lighting device according to claim 11, wherein the curved surface member and the installation surface of the curved surface member form a sealed space.

13. The lighting device according to claim 11 or 12, wherein the curved surface member is a hollow hemispherical member.

14. The light guide unit has a low refractive index layer having a lower refractive index than the curved surface member, The lighting device according to any one of claims 11 to 13, wherein the low refractive index layer is provided on at least a part of at least one of the inner surface and the outer surface of the curved surface member intersecting the light incident end face.

15. The light extraction unit has an optical function layer including at least one of a void portion and a light scattering body inside, The lighting device according to any one of claims 11 to 14, wherein the optical function layer is provided on at least one of the inner surface and the outer surface of the curved surface member intersecting the light incident end face.

16. The light extraction unit has an optical function layer including at least one of a prism unit and an uneven unit on the surface, The lighting device according to any one of claims 11 to 14, wherein the optical function layer is provided on at least a part of at least one of the inner surface and the outer surface of the curved surface member intersecting the light incident end face.

17. The lighting device according to any one of claims 11 to 14, wherein the light extraction unit has at least one of a prism unit and an uneven unit provided on at least a part of at least one of the inner surface and the outer surface of the curved surface member intersecting the light incident end face.

18. The lighting device according to any one of claims 1 to 17, wherein the light guide unit has transparency to visible light. **Claim 19** The lighting device according to any one of claims 1 to 18, wherein the light extraction unit has at least one of a void portion provided in at least a part of the interior of the wall portion and light scattering particles.

Images