Lighting device

Abstract

The present invention addresses the problem of providing a lighting device which has a diffusion plate having excellent impact resistance. This lighting device includes a light source and a diffusion plate that diffuses light from the light source, and the diffusion plate includes cellulose nanofibers.

Description

lighting fixtures

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

[0002] Conventionally, lighting fixtures capable of producing the appearance of a changing sky have been devised. For example, Patent Document 1 describes a lighting fixture including a blue LED (Light Emitting Diode) module that emits light containing a blue light component, a light guide plate that diffuses and surface-emits the light from the LED module, and a dimming unit that adjusts the chromaticity of the light emitted from the light guide plate.

[0003] International Publication No. 2021 / 193612

[0004] Patent Document 1 discloses a light guide plate made of acrylic resin as the light guide plate in the above configuration. However, a large area is sometimes required for a lighting fixture that expresses the above-mentioned transitions in the sky, but if the lighting fixture is made large, the light guide plate also needs to be large in area, and if the light guide plate is made of acrylic resin, the light guide plate will be heavy.

[0005] Therefore, the inventors of the present invention have investigated a light guide plate (diffusion plate) made of porous silica as a lightweight material, and have found that the diffusion plate made of porous silica may have poor impact resistance. Therefore, an object of the present invention is to provide a lighting fixture having a diffusion plate with excellent impact resistance.

[0006] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, they have found that the above problems can be solved by the following configuration.

[0007] [1] A lighting fixture comprising a light source and a diffusion plate that diffuses light from the light source, wherein the diffusion plate contains cellulose nanofibers. [2] The lighting fixture according to [1], wherein the porosity of the diffusion plate is 90% or more. [3] The lighting fixture according to [1] or [2], wherein the thickness of the diffusion plate is 3 mm or more. [4] The lighting fixture according to any one of [1] to [3], wherein the content of the cellulose nanofibers relative to the total mass of the diffusion plate is 70 mass% or more. [5] The lighting fixture according to any one of [1] to [4], wherein the fiber diameter of the cellulose nanofibers is 3 to 30 nm. [6] The lighting fixture according to any one of [1] to [4], wherein the S value calculated by the following formula (1) is 5.0 x 10 ８ ~5.0 x 10 ９ [5] The lighting fixture according to any one of [1] to [5], wherein S=td ６ (1) In formula (1), d represents the fiber diameter of the cellulose nanofiber, and the unit of d is nm. In formula (1), t represents the thickness of the diffusion plate, and the unit of t is mm.

[0008] According to the present invention, it is possible to provide a lighting fixture having a diffusion plate with excellent impact resistance.

[0009] 1 is a perspective view of a first embodiment of a lighting fixture of the present invention; FIG. 2 is a schematic cross-sectional view of the first embodiment of a lighting fixture of the present invention; FIG. 3 is a perspective view of a second embodiment of a lighting fixture of the present invention; FIG. 4 is a schematic cross-sectional view of the second embodiment of a lighting fixture of the present invention; FIG. 5 is a perspective view of a third embodiment of a lighting fixture of the present invention; FIG. 6 is a schematic cross-sectional view of the third embodiment of a lighting fixture of the present invention.

[0010] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0011] The following describes the meaning of each description in this specification. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, specific examples of embodiments are sometimes shown and described, but the present invention is not limited to these examples and can be modified in various ways without departing from the spirit of the present invention. Furthermore, the present invention includes all combinations of possible configurations included in the embodiments shown in this specification. In addition, in each drawing of this specification, items with the same reference numerals are the same or equivalent and are common throughout this specification. Note that the relative dimensional relationships and shapes of each component in each drawing of this specification may differ from the actual ones.

[0012] <First embodiment of lighting fixture> The lighting fixture of the present invention includes a light source and a diffusion plate that diffuses light from the light source, the diffusion plate containing cellulose nanofiber (hereinafter also referred to as "CNF"). Hereinafter, a first embodiment, which is an example of the lighting fixture of the present invention, will be described with reference to the drawings.

[0013] FIG. 1 is a perspective view of a first embodiment of a lighting fixture of the present invention. The lighting fixture 10a shown in FIG. 1 is a lighting fixture that can be attached to the ceiling of a house or the like. The lighting fixture 10a includes a lighting fixture body 14, an LED light source 20a (see FIG. 2), not shown in FIG. 1, and a diffuser panel 12. The lighting fixture 10a is installed on a ceiling with the ceiling facing upward on the paper. The lighting fixture body 14 has a rectangular parallelepiped shape and has a square opening on the side opposite the ceiling side (hereinafter also referred to as the "floor side"), through which the diffuser panel 12 is exposed to the floor side.

[0014] FIG. 2 is a schematic cross-sectional view of the lighting fixture 10a shown in FIG. 1. In the lighting fixture 10a, an LED light source 20a and a diffuser 12 are arranged in this order from the ceiling side to the floor side within the fixture body 14. The LED light source 20a is composed of multiple LED modules 22, and the LED modules 22 emit light downward (toward the floor side) on the paper. In the embodiment shown in FIGS. 1 and 2, the multiple LED modules 22 are arranged at equal intervals in a grid pattern. Light emitted from the LED light source 20a (LED modules 22) is diffused by the diffuser 12, and the light diffused by the diffuser 12 is emitted from the ceiling side toward the floor side through an opening in the fixture body 14.

[0015] 1 and 2, components necessary for mounting the lighting fixture 10a, such as mounting brackets for mounting the lighting fixture 10a on a ceiling, are not shown. Also not shown are a power supply unit that supplies power to the LED light source 20a and a control unit that is connected to the power supply unit and adjusts the amount of light emitted from the LED light source 20a, the color of the light, and the like.

[0016] The power supply unit and the control unit are connected by a signal line. The control unit can control the amount of power supplied from the power supply unit to the LED light source 20a (LED module 22), the power pattern, etc., using signals transmitted from the control unit. The control unit has, for example, a control circuit that transmits control signals to the power supply unit. A known control circuit can be used as the control circuit.

[0017] The power supply unit supplies power to the LED light source 20a (LED module 22) based on a signal from the control unit. The power supply unit also has a terminal (not shown) that can be connected to a power supply source (not shown). The power supply unit and the control unit are usually installed inside the fixture body 14.

[0018] Here, the diffuser plate 12 contains CNF. The inclusion of CNF in the diffuser plate 12 provides the diffuser plate 12 with excellent impact resistance. Furthermore, the diffuser plate 12 diffuses the light emitted from the LED light source 20a, making the shape of the light-emitting portion of the LED module 22 used in the LED light source 20a less visible, and the light is uniformly irradiated toward the floor from within the plane of the diffuser plate 12. In other words, the diffuser plate 12 allows the lighting fixture 10a to emit light from the opening of the fixture body 14. Furthermore, the diffuser plate 12 contains CNF, effectively scattering the light emitted from the LED light source 20a and easily achieving a visual effect with a sense of depth. Preferred embodiments of the diffuser plate 12 are described below.

[0019] [Diffusion plate 12] The diffusion plate 12 contains cellulose nanofibers (CNF). There are no particular limitations on the CNF, and known CNFs can be used. Note that CNF refers to a material in which two or more cellulose molecular chains form bundles. The term "cellulose molecular chains form bundles of two or more" refers to a state in which two or more cellulose molecular chains are aggregated to form an aggregate called a microfibril.

[0020] CNF is generally obtained by processing plant-derived fibers. The raw material for CNF is not particularly limited, and examples thereof include plant-derived fibers contained in wood, bamboo, hemp, jute, kenaf, cotton, beet pulp, potato pulp, agricultural waste, cloth, and paper. As the raw material for CNF, these may be used alone or in combination of two or more.

[0021] CNF may be chemically modified, and chemically modified CNF is preferred because it is easier to increase the transmittance of the transparent heat insulating material. In chemically modified CNF, some or all of the groups in the cellulose molecular chain are changed by chemical treatment. For example, the cellulose molecular chain in chemically modified CNF may be oxidized to aldehyde groups, carboxyl groups, etc., some or all of the hydroxyl groups at the C6 position in the molecule, including hydroxyl groups at positions other than the C6 position, esterified CNF such as nitrate ester, acetate ester, phosphate ester, or etherified CNF such as methyl ether, hydroxypropyl ether, carboxymethyl ether, or substituted with other functional groups.

[0022] The method for preparing CNF is not particularly limited, and a mechanical or chemical disintegration method is preferred. Examples of the mechanical disintegration method include a method in which an aqueous suspension or slurry of a cellulose fiber-containing material is mechanically ground or beaten using a refiner, a high-pressure homogenizer, a grinder, a single- or multi-screw kneader, a bead mill, or the like to disintegrate the material. Examples of mechanical processing methods include Japanese Patent No. 5500842, Japanese Patent No. 5283050, Japanese Patent No. 5207246, Japanese Patent No. 5170193, Japanese Patent No. 5170153, Japanese Patent No. 5099618, Japanese Patent No. 4845129, Japanese Patent No. 4766484, Japanese Patent No. 4724814, Japanese Patent No. 4721186, Japanese Patent No. 4428521, International Publication No. 11 / 068023, Japanese Patent No. 5477265, and Japanese Patent Laid-Open No. 2014-84434. On the other hand, examples of chemical disintegration methods include oxidizing a cellulosic raw material using an oxidizing agent in the presence of an N-oxyl compound and a bromide and / or iodide, and then subjecting the oxidized cellulose to wet atomization for defibration into nanofibers. Examples of chemical treatment methods include those described in Japanese Patent Nos. 5,381,338, 4,981,735, 5,404,131, 5,329,279, 5,285,197, 5,179,616, 5,178,931, 5,330,882, and 5,397,910.

[0023] The diffusion plate 12 is preferably a porous body containing CNF in order to reduce the weight of the diffusion plate. The porosity of the diffusion plate 12 is preferably 50% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more in order to reduce the weight of the diffusion plate 12. The porosity of the diffusion plate 12 is less than 100%, and is often 99.5% or less. The porosity is a value calculated by measuring the bulk density and true density of the diffusion plate 12. The methods for measuring the bulk density and true density and the method for calculating the porosity follow the methods described in the examples below.

[0024] The content of CNF relative to the total mass of the diffusion plate 12 is preferably 50 mass% or more, more preferably 70 mass% or more, and even more preferably 75 mass% or more. The upper limit of the CNF content is not particularly limited, but may be less than 100 mass%, and preferably 99 mass% or less.

[0025] The fiber diameter of the CNFs in the diffuser plate 12 is preferably 1 to 50 nm, more preferably 2 to 40 nm, even more preferably 3 to 40 nm, particularly preferably 3 to 30 nm, and most preferably 15 to 30 nm. The fiber diameter of the CNFs in the diffuser plate 12 is measured by small angle X-ray scattering (SAXS). The method for measuring the CNF fiber diameter in the diffuser plate 12 follows the method described in the Examples below. When the fiber diameter of the CNFs in the diffuser plate 12 is adjusted to fall within the above range, the light emitted from the diffuser plate 12 tends to be more uniform in the in-plane direction of the diffuser plate 12.

[0026] The thickness of the diffuser plate 12 is preferably 0.5 mm or more, more preferably 2 mm or more, even more preferably 3 mm or more, and particularly preferably 8 mm or more. The thickness of the diffuser plate 12 is often 30 mm or less. When the thickness of the diffuser plate 12 is adjusted to fall within the above-mentioned preferred range, the light emitted from the diffuser plate 12 tends to become more uniform in the in-plane direction of the diffuser plate 12.

[0027] In addition, in the diffuser 12, the S value calculated by the following formula (1) is 1.0×10 ７ ~1.0 x 10 １０ It is preferable that the ８ ~5.0 x 10 ９ More preferably, it is 5.0 × 10 ８ ~5.0 x 10 ９ It is more preferable that S=td ６(1) In formula (1), d represents the numerical value of the fiber diameter of the CNF measured by the above method, and the unit of d is nm. That is, if the fiber diameter of the CNF is 20 nm, the value of d is set to 20 to calculate the S value. In formula (1), t represents the numerical value of the thickness of the diffuser plate 12, and the unit of t is mm. That is, if the thickness of the diffuser plate 12 is 5 mm, the value of t is set to 5 to calculate the S value. When the S value calculated by formula (1) is within the above range, the light irradiated from the diffuser plate 12 tends to be uniform in the in-plane direction of the diffuser plate 12, and a visual effect with a sense of depth is easily obtained.

[0028] The diffusion plate 12 may contain components other than CNF, such as a water-repellent component, an antifreeze agent, and a strength modifier.

[0029] Examples of the water-repellent component include fluorine-based water-repellent agents, silicone-based water-repellent agents, wax-based water-repellent agents, alkyl ketene dimers, and hydrolysis condensates of alkoxysilanes. Another preferred example of the generating component is a surfactant. Here, the surfactant refers to a compound having a hydrophobic group and a hydrophilic group in the molecule. The content of the water-repellent component is preferably 0.001 to 10% by mass, and more preferably 0.01 to 5% by mass, relative to the total mass of the diffusion plate 12.

[0030] The antifreeze agent is an additive that inhibits water from freezing, and examples thereof include water-soluble polymers, sugars, and antifreeze proteins. Among these, antifreeze proteins are preferred. The content of the antifreeze agent is preferably 1 to 40% by mass, and more preferably 10 to 30% by mass, relative to the total mass of the diffusion plate 12.

[0031] Examples of the strength modifier include various latex emulsions such as acrylic latex, NBR latex, vinyl acetate latex, and olefin latex, as well as water-soluble polymers such as polyacrylamide, polyamide epichlorohydrin, polyvinyl alcohol, and starch. The content of the strength modifier is preferably 5% by mass or less, and more preferably 1% by mass or less, based on the total mass of the diffusion plate 12.

[0032] The diffuser plate 12 may have a single layer structure or a multi-layer structure. When the diffuser plate 12 has a multi-layer structure, at least one of the layers constituting the diffuser plate 12 contains CNF. When the diffuser plate 12 has a multi-layer structure, the layer of the diffuser plate 12 farthest from the LED light source 20a side is preferably a scratch-resistant layer (for example, a hard coat layer).

[0033] The diffusion plate 12 containing CNF can be manufactured by a manufacturing method that includes, in this order, the steps of preparing a CNF dispersion liquid in which CNFs are dispersed, gelling the CNF dispersion liquid to obtain a CNF wet gel, replacing the solvent components in the CNF wet gel, and freeze-drying the CNF wet gel to obtain a CNF aerogel.

[0034] First, a CNF dispersion in which CNFs are dispersed is prepared. The CNF dispersion in which CNFs are dispersed can be obtained, for example, by the method described in the CNF preparation method above. The dispersion medium in the CNF dispersion preferably contains water, and the dispersion medium preferably contains 70 mass% or more of water, more preferably 90 mass% or more, and even more preferably 99 mass% or more of water, relative to the total mass of the dispersion medium. The dispersion medium in the CNF dispersion may be water. The CNF content in the CNF dispersion is preferably 0.001 to 5 mass%, more preferably 0.01 to 2 mass%, and even more preferably 0.1 to 1 mass%. The CNF dispersion may contain the additives described above.

[0035] Next, the CNF dispersion is gelled to obtain a CNF wet gel. The method for gelling the CNF dispersion is not particularly limited, but examples include adding an acidic or alkaline component, with the addition of an acidic component being preferred. The addition of the above component weakens the electrostatic repulsion that contributes to the dispersion of CNFs in the CNF dispersion, forming a CNF network and thus obtaining a CNF wet gel. The acidic component to be added is not particularly limited, but examples include inorganic acids (e.g., hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid), organic acids (e.g., methanesulfonic acid, tosylic acid), and metal halides (e.g., aluminum chloride). The acidic component is preferably added to the CNF dispersion in the form of a solution. The amount of the acidic component added can be adjusted as appropriate, but it is preferable to add it so that the total volume of the CNF dispersion after the addition of the acidic component is 0.01 to 5 mol / L. It is also preferable to add the acidic component without forcible stirring and then allow it to stand.

[0036] Next, the solvent components in the CNF wet gel are replaced. The solvent components in the CNF wet gel are preferably replaced with a solvent that precipitates fine crystals during the subsequent freezing step. Examples of solvents that precipitate fine crystals include mixed solvents, with a mixed solvent of water and alcohol being particularly preferred. The mixed solvent is preferably prepared in a ratio that allows the components contained in the mixed solvent to precipitate as a eutectic when the temperature is lowered. Examples of alcohols include alcohols that are miscible with water at any ratio, with t-butyl alcohol being preferred. Mixed solvents of water and t-butyl alcohol preferably contain 3 to 20% by mass of water, more preferably 5 to 15% by mass, based on the total mass of the mixed solvent. In the mixed solvent, the component other than water is preferably t-butyl alcohol. The solvent components in the CNF wet gel can be replaced by known methods, for example, by immersing the CNF wet gel in the mixed solvent. Shaking may be performed to promote the replacement.

[0037] Next, the CNF wet gel with the solvent components replaced is freeze-dried to obtain a CNF aerogel. Freezing can be performed by known methods, but rapid cooling is preferred to reduce the size of crystals precipitated from the solvent contained in the CNF wet gel and obtain a transparent insulation material with higher transmittance. A rapid cooling method includes, for example, contacting the CNF wet gel with a member cooled with liquid nitrogen. After freezing the CNF wet gel, the solvent components in the frozen CNF wet gel are sublimated. The solvent components can be sublimated by placing the frozen CNF wet gel in an environment below the freezing point of the solvent components. During the sublimation of the solvent components, the sublimation rate can be increased by reducing the pressure.

[0038] The above steps produce a CNF aerogel, which can be preferably used for the above-mentioned diffusion plate 12. As another embodiment of the method for producing a porous cellulose body, the freeze-drying performed in the above steps may be replaced with a process in which the solvent component in the CNF wet gel is replaced with a supercritical fluid, followed by drying.

[0039] The LED light source 20a is not particularly limited, but preferably emits at least white light. For example, an LED module 22 that emits white light may be used, or an array of LED modules 22 that emit red, green, and blue light may be used to emit white light. It is also preferable that the LED light source 20a uses an LED module 22 with an adjustable light output, and the color of the emitted light is adjusted by a control unit that controls the amount and pattern of power supplied from a power supply unit connected to the LED module 22. For example, the control unit may adjust the color temperature of the light emitted by the LED light source 20a, or the color of the light may be adjusted according to the time and season to create the illusion of changing sky colors.

[0040] 1 and 2 may have other configurations that are common to conventional lighting fixtures. For example, the diffuser plate 12 may have a cover that protects at least a portion of the portion exposed through the opening of the fixture body 14. The cover is optically transparent so as to transmit light from the LED light source 20a that is irradiated through the diffuser plate 12.

[0041] 1 and 2 may be modified in various ways as described below. The following modifications may be combined, or conventionally known modifications may be combined.

[0042] Lighting fixture 10a may be installed on a wall surface perpendicular to the ceiling and floor, in addition to the ceiling. The wall surface is not limited to a wall surface perpendicular to the ceiling and floor, and may be a wall surface at any angle. Lighting fixture 10a may also be installed on a floor. Lighting fixture 10a may have one or more legs, one end of which is fixed to fixture body 14, and may be self-supporting by the legs. Lighting fixture 10a may be installed so that the surface of the ceiling, wall, floor, etc., and the surface of fixture body 14 having an opening are substantially aligned. In other words, lighting fixture 10a may be disposed so as to be recessed into the surface.

[0043] The arrangement of the LED modules 22 may be changed as appropriate. For example, the LED modules 22 may be arranged at equal intervals in a triangular shape. Furthermore, the LED modules 22 do not have to be arranged at equal intervals. For example, the arrangement density of the LED modules 22 may be high in the center of the opening of the fixture body 14 and low at the edges of the opening of the fixture body 14. Alternatively, the arrangement density of the LED modules 22 may be low in the center of the opening of the fixture body 14 and high at the edges of the opening of the fixture body 14. Furthermore, the LED modules 22 may be arranged only at the edges of the opening of the fixture body 14 or only at the center of the opening of the fixture body 14. Furthermore, the LED modules 22 may be arranged only outside the opening of the fixture body 14, and the diffuser plate 12 may diffuse light in the left-right direction of the page in FIG. 2, so that part of the diffused light is irradiated through the opening of the fixture body 14.

[0044] The fixture body 14 may be composed of multiple parts. For example, in the embodiment described with reference to Figures 1 and 2, the fixture body 14 may be composed of a lower cover that defines the opening of the fixture body 14, and a housing that houses the diffuser plate 12 and the LED light source 20a, etc.

[0045] The opening of the device body 14 may have a shape other than a square. The shape of the opening may be, for example, a polygon or a circle. Furthermore, there may be two or more openings.

[0046] The shape of the fixture body 14 may be a shape other than a rectangular parallelepiped. For example, it may be a cylindrical shape or a polygonal columnar shape. Furthermore, the shape of the fixture body 14 may be a shape with a curved surface, such as a sphere or a spherical crown shape formed by cutting out a part of a sphere, as long as it has an opening in a part of the fixture body 14. When the shape of the fixture body 14 is a shape other than a rectangular parallelepiped, the shapes of the other components, such as the diffuser plate 12, are adjusted appropriately.

[0047] <Second embodiment of lighting fixture> The lighting fixture of the present invention includes a light source and a diffusion plate that diffuses light from the light source, the diffusion plate containing cellulose nanofiber (CNF). Hereinafter, a second embodiment of the lighting fixture of the present invention will be described with reference to the drawings.

[0048] Fig. 3 is a perspective view of a second embodiment of the lighting fixture of the present invention. The lighting fixture 10b shown in Fig. 3 is a lighting fixture that can be attached to the ceiling of a house or the like. The lighting fixture 10b includes a lighting fixture body 14, an LED light source 20b (see Fig. 4 ), not shown in Fig. 1 , and a diffuser plate 12. The lighting fixture 10b is installed on a ceiling with the ceiling facing upward in the plane of the drawing. The lighting fixture body 14 is shaped like a rectangular parallelepiped and has a square opening on the floor side, through which the diffuser plate 12 is exposed to the floor side.

[0049] FIG. 4 is a schematic cross-sectional view of the lighting fixture 10b shown in FIG. 3. In the lighting fixture 10b, an LED light source 20b and a diffuser plate 12 are disposed within the fixture body 14. The LED light source 20b is composed of multiple LED modules 22, which are disposed on the side surfaces of the diffuser plate 12 and emit light in a direction substantially perpendicular to the surface of the fixture body 14 having the opening. In the embodiment shown in FIGS. 3 and 4, the LED modules 22 are disposed at equal intervals around the entire side surface of the diffuser plate 12. Light emitted from the LED light source 20b (LED modules 22) enters the side surface of the diffuser plate 12 and is diffused by the diffuser plate 12, changing the direction of travel of some of the light. The light diffused by the diffuser plate 12 is emitted from the ceiling side toward the floor side through the opening of the fixture body 14. That is, in the lighting fixture 10b, the diffuser plate 12 functions to guide the light from the LED light source 20b (LED modules 22).

[0050] 3 and 4, the components necessary for mounting the lighting fixture 10b, such as mounting brackets for mounting the lighting fixture 10b on a ceiling, are not shown. Also not shown are a power supply unit that supplies power to the LED light source 20b and a control unit that is connected to the power supply unit and adjusts the amount of light emitted from the LED light source 20b, the color of the light, etc. The configurations of the power supply unit and the control unit are the same as those described in the first embodiment, and therefore will not be described here.

[0051] Here, the diffuser plate 12 contains CNF. The inclusion of CNF in the diffuser plate 12 provides the diffuser plate 12 with excellent impact resistance. Furthermore, light emitted from the LED light source 20b is diffused by the diffuser plate 12 and irradiated toward the floor through the opening of the fixture body 14. Therefore, the diffuser plate 12 allows the lighting fixture 10b to emit light from the opening of the fixture body 14. Furthermore, the diffuser plate 12 contains CNF, which effectively scatters the light emitted from the LED light source 20b, thereby creating a visual effect that creates a sense of depth. Note that preferred aspects of the diffuser plate 12 in the second embodiment are similar to those of the diffuser plate 12 in the first embodiment, and therefore a description thereof will be omitted. However, in the diffuser plate 12 in the second embodiment, the fiber diameter of the CNF is preferably 1 to 50 nm, more preferably 5 to 40 nm, even more preferably 8 to 40 nm, particularly preferably 10 to 30 nm, and most preferably 10 to 20 nm. The thickness of the diffusion plate 12 in the second embodiment is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 4 mm or more. The thickness of the diffusion plate 12 is often 30 mm or less.

[0052] Like the LED light source 20a of the first embodiment described above, the LED light source 20b preferably emits at least white light. For example, an LED module 22 that emits white light may be used, or an array of LED modules 22 that emit red, green, and blue light may be used to emit white light. Furthermore, the LED light source 20b preferably uses LED modules 22 with adjustable light output, and adjusts the color of the emitted light using a control unit that controls the amount and pattern of power supplied from a power supply unit connected to the LED modules 22. For example, the control unit may adjust the color temperature of the light emitted by the LED light source 20b, or may adjust the color of the light according to the time and season to create the illusion of changing sky colors.

[0053] The lighting fixture 10b shown in FIGS. 3 and 4 may have other configurations that are common to lighting fixtures.

[0054] For example, the diffuser plate 12 may have a cover that protects at least a part of the portion exposed through the opening of the fixture body 14. The cover has optical transparency so as to transmit light from the LED light source 20b that is irradiated through the diffuser plate 12.

[0055] The lighting fixture 10b may have a reflective sheet between the diffuser plate 12 and the fixture body 14. The reflective sheet has the function of reflecting light diffused by the diffuser plate 12 that travels toward the interior of the fixture body 14 (upward in the plane of FIG. 4 ) toward the opening of the fixture body 14 (downward in the plane of FIG. 4 ). A known reflective member having a light-reflecting function can be used as the reflective sheet. The reflective sheet may be disposed in contact with the diffuser plate 12 or spaced apart from the diffuser plate 12.

[0056] 3 and 4 may be modified in various ways as described below. The following modifications may be combined, or conventionally known modifications may be combined.

[0057] The lighting fixture 10b may be installed on a surface other than the ceiling. The installation manner is similar to that of the lighting fixture 10a described in the first embodiment, and therefore a description thereof will be omitted.

[0058] The arrangement of the multiple LED modules 22 may be changed as appropriate. For example, the LED modules 22 may be arranged on one or more side surfaces of the diffuser plate 12. For example, the LED modules 22 may be arranged on only one side surface of the diffuser plate 12, on two opposing side surfaces of the diffuser plate 12, or on two adjacent side surfaces of the diffuser plate 12. Furthermore, the LED modules 22 do not need to be arranged at equal intervals. For example, the arrangement density of the LED modules 22 may be higher in the center of one side surface of the diffuser plate 12 and lower at the end portions of one side surface of the diffuser plate 12. Alternatively, the arrangement density of the LED modules 22 may be lower in the center of one side surface of the diffuser plate 12 and higher at the end portions of one side surface of the diffuser plate 12. Alternatively, the LED modules 22 may be arranged only on the end portions of one side surface of the diffuser plate 12 or only on the center portions of one side surface of the diffuser plate 12. In addition, in addition to being arranged on the side of the diffuser plate 12, the LED module 22 may also be arranged on the side opposite the opening side of the diffuser plate 12, like the LED light source 20a arranged in the lighting fixture 10a described in the first embodiment.

[0059] The deformation of the instrument body 14 in the second embodiment is similar to that described in the first embodiment, and therefore a description thereof will be omitted.

[0060] The present invention relates to a lighting fixture, and more particularly to a lighting fixture according to the present invention.

[0061] FIG. 5 is a perspective view of a third embodiment of the lighting fixture of the present invention. The lighting fixture 10c shown in FIG. 5 is a lighting fixture that can be attached to the ceiling of a house or the like. The lighting fixture 10c includes a lighting fixture body 14, an LED light source 20c (see FIG. 6 ), not shown in FIG. 1 , and a cover 18. The lighting fixture 10c is installed on a ceiling with the ceiling facing upward in the plane of the drawing. The lighting fixture body 14 is rectangular parallelepiped-shaped, with a square-shaped opening on the floor side. A truncated pyramidal cover 18 is disposed in the opening. The cover 18 has a truncated pyramidal shape with a transmissive plate 16 on its side and a diffuser plate 12 on its top. The transmissive plate 16 has a predetermined transmittance and transmits at least a portion of the light incident on the transmissive plate 16.

[0062] FIG. 6 is a schematic cross-sectional view of the lighting fixture 10c shown in FIG. 5. In the lighting fixture 10c, an LED light source 20c and a cover 18 are disposed within the fixture body 14. As described above, the cover 18 has a truncated quadrangular pyramid shape with the translucent plate 16 on the side and the diffuser plate 12 on the top. The cover 18 is disposed in contact with the side of the opening of the fixture body 14. Furthermore, the end of the diffuser plate 12 and the end of the translucent plate 16 are disposed in contact with each other. The LED light source 20c is composed of a plurality of LED modules 22, which are disposed on the side of the cover 18 and emit light in a direction substantially perpendicular to the surface of the fixture body 14 that has the opening. In the embodiment shown in FIGS. 5 and 6, the LED modules 22 are disposed at equal intervals around the entire periphery of the side of the cover 18. A portion of the light emitted from LED light source 20c (LED module 22) onto cover 18 enters from the side of diffuser plate 12, is diffused by diffuser plate 12, and changes the direction of travel of some of the light. The light diffused by diffuser plate 12 is then emitted from the ceiling toward the floor through the opening in fixture body 14. That is, in lighting fixture 10c, diffuser plate 12 has the function of guiding the light from LED light source 20c (LED module 22). Furthermore, a portion of the light emitted from LED light source 20c (LED module 22) onto cover 18 enters the portion formed by transmissive plate 16, and is then emitted from the ceiling toward the floor through the opening in fixture body 14.

[0063] 5 and 6, the components necessary for mounting the lighting fixture 10c, such as mounting brackets for mounting the lighting fixture 10c on a ceiling, are not shown. Also not shown are a power supply unit that supplies power to the LED light source 20c and a control unit that is connected to the power supply unit and adjusts the amount of light emitted from the LED light source 20c, the color of the light, etc. The configurations of the power supply unit and the control unit are the same as those described in the first embodiment, and therefore will not be described here.

[0064] Here, the diffuser plate 12 contains CNF. The CNF content of the diffuser plate 12 provides excellent impact resistance. Furthermore, a portion of the light emitted from the LED light source 20c is diffused by the diffuser plate 12 and irradiated toward the floor through the opening in the fixture body 14. The diffuser plate 12 allows the lighting fixture 10c to emit light from the opening in the fixture body 14. Additionally, a portion of the light emitted from the LED light source 20c is irradiated from the transparent plate 16 toward the floor through the opening in the fixture body 14. Thus, the lighting fixture 10c can emit light with two different ambiences. Furthermore, the CNF content of the diffuser plate 12 effectively scatters the light emitted from the LED light source 20c, easily creating a visual effect with a sense of depth. Note that preferred aspects of the diffuser plate 12 in the third embodiment are the same as those of the diffuser plate 12 in the second embodiment, and therefore, a description thereof will be omitted.

[0065] Like the LED light source 20a of the first embodiment described above, the LED light source 20c preferably emits at least white light. For example, an LED module 22 emitting white light may be used, or an LED module 22 emitting red, green, and blue light may be arranged to emit white light. The LED light source 20c also preferably uses LED modules 22 with adjustable light output, and the color of the emitted light is adjusted by a control unit that controls the amount and pattern of power supplied from a power supply unit connected to the LED modules 22. For example, the control unit may adjust the color temperature of the light emitted by the LED light source 20c, or adjust the color of the light according to the time and season to create a visual effect such as the changing colors of the sky. Furthermore, the LED light source 20c may include LED modules 22 for transmitting light through the transmission plate 16 and LED modules 22 for directing light to the side of the diffusion plate 12. The lighting fixture 10c shown in FIGS. 3 and 4 may have other configurations that are common to typical lighting fixtures.

[0066] The transmission plate 16 is not particularly limited as long as it has a predetermined transmittance, but the transmittance may be, for example, 50 to 99%. The transmission plate 16 may have light diffusing properties.

[0067] For example, the diffuser plate 12 may have a cover that protects at least a part of the portion exposed through the opening of the fixture body 14. The cover has optical transparency so as to transmit light from the LED light source 20a irradiated through the diffuser plate 12.

[0068] The lighting fixture 10b may have a reflective sheet between the diffuser plate 12 and the fixture body 14. The reflective sheet has the function of reflecting light diffused by the diffuser plate 12 that travels toward the interior of the fixture body 14 (upward in the plane of FIG. 4 ) toward the opening of the fixture body 14 (downward in the plane of FIG. 4 ). A known reflective member having a light-reflecting function can be used as the reflective sheet. The reflective sheet may be disposed in contact with the diffuser plate 12 or spaced apart from the diffuser plate 12.

[0069] 5 and 6 may be modified in various ways as described below. The following modifications may be combined, or conventionally known modifications may be combined.

[0070] The lighting fixture 10c may be installed on a surface other than the ceiling. The installation manner is similar to that of the lighting fixture 10a described in the first embodiment, and therefore a description thereof will be omitted.

[0071] The arrangement of the multiple LED modules 22 may be changed as appropriate. For example, the LED modules 22 may be arranged on one or more side surfaces of the cover 18. For example, the LED modules 22 may be arranged on only one side surface of the cover 18, on two opposing side surfaces of the cover 18, or on two adjacent side surfaces of the cover 18. Furthermore, the LED modules 22 do not need to be arranged at equal intervals. For example, the arrangement density of the LED modules 22 may be higher in the center of one side of the cover 18 and lower at the end of one side of the cover 18. Alternatively, the arrangement density of the LED modules 22 may be lower in the center of one side of the cover 18 and higher at the end of one side of the cover 18. Alternatively, the LED modules 22 may be arranged only at the end of one side of the cover 18 or only at the center of one side of the cover 18. In addition, in addition to being arranged on the side of the cover 18, the LED module 22 may also be arranged on the side opposite the opening side of the diffuser plate 12, like the LED light source 20a arranged in the lighting fixture 10a described in the first embodiment.

[0072] The deformation of the instrument body 14 in the third embodiment is the same as that described in the first embodiment, and therefore a description thereof will be omitted.

[0073] In the first, second and third embodiments, examples have been described in which an LED light source is used as the light source, but the LED light source may be replaced with other known light sources.

[0074] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0075] Example 1 First, the diffusion plate 12 used in Example 1 was obtained by the following procedure.

[0076] [Preparation process of cellulose nanofiber aqueous dispersion] 2.00 g of NBKP (mainly consisting of fibers with a fiber diameter exceeding 1000 nm) in dry mass, 0.025 g of TEMPO (2,2,6,6-tetramethylpiperidine-1-oxy radical), and 0.25 g of sodium bromide were dispersed in 150 ml of water, and then a 13% aqueous sodium hypochlorite solution was added to 1.00 g of pulp (NBKP) so that the amount of sodium hypochlorite was 5.00 mmol. The reaction was initiated by adding sodium hypochlorite. During the reaction, a 0.50 mol / L aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10. After the reaction for 2 hours, the reaction product was filtered and thoroughly washed with water to obtain an oxidized cellulose slurry. A 0.15% by mass oxidized cellulose slurry was defibrated for 5 minutes at 15,000 rpm using a Biomixer (BM-2, manufactured by Nippon Seiki Seisakusho Co., Ltd.), and then further defibrated for 20 minutes using an ultrasonic disperser (Model US-300E, manufactured by Nippon Seiki Seisakusho Co., Ltd.). Coarse fibers were then removed by centrifugation to obtain a transparent aqueous dispersion of cellulose nanofibers. The resulting aqueous dispersion of cellulose nanofibers was concentrated using a rotary evaporator to a solids concentration of 0.40% and used in subsequent steps.

[0077] [Preparation of Mixture] Highly purified fish-derived type I antifreeze protein (manufactured by Nichirei) was added to the cellulose nanofiber dispersion to a concentration of 0.08% by mass, and the mixture was stirred with a magnetic stirrer.

[0078] [Gelling Step] The cellulose nanofiber aqueous dispersion A was poured into a petri dish, and 1.0 M hydrochloric acid was gently poured down the side wall, followed by standing for 1 hour. The dispersion was physically gelled.

[0079] [Solvent substitution step] The solvent was substituted with a mixed solvent of t-butyl alcohol and water in a mass ratio of 90:10. The solvent substitution was carried out by immersing the physical gel in a sufficient amount of the substitution solvent and shaking it slowly. Each substitution step was carried out over 4 hours, and substitution was carried out four or more times.

[0080] [Freeze-drying step] The gel obtained in the solvent substitution step was sandwiched between iron plates sufficiently cooled with liquid nitrogen (-196°C) and frozen. The completely frozen gel was then dried in a vacuum dryer (manufactured by Tokyo Rikakikai Co., Ltd.) to sublimate the dispersion medium, thereby obtaining aerogel A. The thickness of aerogel A was 10 mm.

[0081] The aerogel A obtained by the above procedure was used as the diffuser plate 12 to fabricate the lighting fixture 10a shown in Figures 1 and 2. Specifically, 28 x 35 3.5 mm x 2.8 mm LED chips (manufactured by INEX) were arranged in a grid pattern as the LED module 22 to fabricate the LED light source 20a. The aerogel A was processed into a 10 cm square and placed in the fixture body 14 (manufactured by ZEBRA) with an 8 cm square opening. The LED light source 20a was placed on the side opposite the opening of the aerogel A (diffuser plate 12), thereby obtaining the lighting fixture 10a.

[0082] Example 2 Aerogel B was obtained in the same manner as aerogel A, except that t-butyl alcohol was used instead of the mixed solvent in the solvent substitution step. The thickness of aerogel B was 5 mm. A lighting device 10a was obtained in the same manner as in Example 1, using aerogel B as the diffuser plate 12.

[0083] Example 3 Aerogel C was obtained in the same manner as Aerogel A, except that ethanol was used instead of the mixed solvent in the solvent substitution step and the freeze-drying step was replaced by the supercritical drying step described below. The thickness of Aerogel C was 5 mm. A lighting device 10a was obtained in the same manner as Example 1, using Aerogel C as the diffuser plate 12.

[0084] [Supercritical Drying Process] The solvent-substituted physical gel was placed in a sealed reactor, and then liquefied carbon dioxide was introduced into the sealed reactor. The sealed reactor was then heated and the pressure inside the sealed reactor was increased using a high-pressure pump, bringing the carbon dioxide inside the sealed reactor to a supercritical state. The liquefied carbon dioxide was then introduced into the sealed reactor, and the supercritical carbon dioxide was then discharged from the sealed reactor, thereby allowing the supercritical carbon dioxide to flow through the physical gel inside the sealed reactor. When the supercritical carbon dioxide flows through the solvent-substituted physical gel, the solvent dissolves in the supercritical carbon dioxide, and the solvent is removed along with the supercritical carbon dioxide flowing out of the sealed reactor. The temperature and pressure inside the sealed reactor were set to those that would bring the carbon dioxide to a supercritical state. The critical point of carbon dioxide is 31.1°C / 7.38 MPa, and the temperature and pressure were, for example, 50 to 200°C / 10 to 30 MPa.

[0085] Example 4 Aerogel D was obtained in the same manner as Aerogel A, except that distilled water was used instead of the mixed solvent in the solvent substitution step, and the freeze-drying step was replaced by the heated steam drying step described below to obtain the aerogel. The thickness of Aerogel D was 2 mm. A lighting device 10a was obtained in the same manner as Example 1, using Aerogel D as the diffuser plate 12.

[0086] [Heated Steam Drying Step] The physical gel was placed in a superheated steam dryer set to a temperature of 100°C and a humidity of 50%, and dried at a pressure of 100 MPa and a drying temperature of 100°C.

[0087] Example 5 Aerogel E was obtained in the same manner as Aerogel A, except that hexane was used instead of the mixed solvent in the solvent substitution step and that the aerogel was obtained by natural drying at normal pressure instead of the freeze-drying step. The thickness of Aerogel E was 0.5 mm. A lighting device 10a was obtained in the same manner as Example 1, using Aerogel E as the diffuser plate 12.

[0088] Comparative Example 1 The diffusion plate used in Comparative Example 1 was obtained according to the following procedure.

[0089] [Silica gelation step] Tetraethyl orthosilicate, ethanol, and water were mixed in a mass ratio of 10:50:40 to obtain a mixed solution. The mixed solution was poured into a petri dish, and 1.0 M hydrochloric acid was added and mixed until homogenous. After mixing, propanetriol was further added dropwise and mixed, and the mixture was allowed to stand for 1 hour to obtain a physical gel.

[0090] Using the physical gel obtained by the above procedure, a solvent substitution step was carried out in the same manner as in Example 1, except that ethanol was used instead of the mixed solvent. After the solvent substitution step, a supercritical drying step was carried out in the same manner as in Example 3, to obtain aerogel F. Aerogel F was used as the diffuser plate 12, and a lighting device 10a was obtained in the same manner as in Example 1.

[0091] <Measurement> [Fiber Diameter] The fiber diameter of each aerogel obtained was calculated by measuring small-angle X-ray scattering (SAXS). Specifically, the calculation was performed according to the following method. The scattering intensity was normalized based on the incident X-ray intensity transmitted through the beam stopper to obtain a scattering curve for the aerogel. A blank measurement was also performed, and a scattering curve for the medium (air) was obtained in the same manner. The scattering curve I(q) for the fibers constituting the aerogel was obtained by subtracting the scattering curve for the medium from the scattering curve for the aerogel. Here, q is the scattering vector calculated using the following formula using the scattering angle 2θ: q = 4 * π * (sin(θ)) / λ (π: pi, 2θ: scattering angle [rad], λ: X-ray wavelength [nm]). When the scattering curve I(q) of the obtained cellulose porous body is plotted on a double logarithmic graph, a region with a linear slope appears. For this region, a Guinier plot for the cross section was created, and the scattering intensity average fiber diameter Dc was calculated using the following formula. q*I(q) ∝ exp(-(Dc ２ * q ２ ) / 16) The scattering intensity average fiber diameter Dc calculated by the above formula was taken as the fiber diameter of the CNFs in the aerogel.

[0092] [Porosity] First, the bulk density and true density were calculated using the following method. The bulk density was calculated by dividing the mass of the aerogel by the volume of the aerogel. The volume of the aerogel was calculated from the external shape of the aerogel. The true density was measured using a gas displacement true density measuring device (manufactured by Microtrac Bell). The porosity (unit: %) was calculated using the following formula: (Porosity) = 100 * (1 - (bulk density) / (true density))

[0093] <Evaluation> [Impact Resistance] Each aerogel was dropped from a height of 5 cm onto a concrete floor to apply an impact and check whether it broke or cracked. The results are shown in the table below.

[0094] [In-plane light emission uniformity] For the lighting fixtures of the above examples and comparative examples, the uniformity of the amount of light emitted in the in-plane direction on the diffuser plate 12 when the LED light source 20a was turned on was visually observed, and the in-plane light emission uniformity was evaluated according to the following criteria. For in-plane light emission uniformity, ratings A to C are preferable, with ratings A or B being more preferable, and rating A being even more preferable. The results are shown in the table below. A: The amount of light appears uniform across the entire surface B: The amount of light appears non-uniform in a very small area within the surface C: The amount of light appears non-uniform in a small area within the surface D: The amount of light appears non-uniform across the entire surface

[0095] [Sense of depth] In the lighting fixtures of the above examples and comparative examples, the sense of depth was visually observed when the LED light source 20a was turned on, and was evaluated according to the following criteria. For the sense of depth, ratings A to C are preferable, with ratings A or B being more preferable, and rating A being even more preferable. The results are shown in the table below. A: A strong sense of depth is felt B: A sense of depth is felt C: A slight sense of depth is felt D: No sense of depth is felt

[0096] <Results> Table 1 shows the measurement results of the diffuser plate 12 of each example and comparative example, and the evaluation results of the lighting fixtures of each example and comparative example. In Table 1, the evaluation results of impact resistance are recorded as B when breakage or cracking occurred during the above evaluation, and A when no breakage or cracking occurred. In Table 1, the "S value" column is the value calculated by the above formula (1). For example, the notation "1.0.E+08" represents 1.0 x 10 ８ Represents.

[0097]

[0098] From the results shown in the table, it was confirmed that Comparative Example 1, which used a diffuser plate containing no CNF, had poor impact resistance. On the other hand, it was confirmed that the diffuser plates containing CNF used in each Example had excellent impact resistance. Furthermore, a comparison of Example 5 with Examples 1 to 4 (preferably Examples 1 to 3) confirmed that when the porosity of the diffuser plate was 90% or more, excellent in-plane light emission uniformity was achieved. A comparison of Example 5 with Examples 1 to 4 (preferably Examples 1 to 3) confirmed that when the thickness of the diffuser plate was 3 mm or more, excellent in-plane light emission uniformity was achieved. A comparison of Examples 3 and 5 with Examples 1, 2, and 4 confirmed that when the fiber diameter of the CNF was 3 to 30 nm (more preferably 15 to 30 nm), excellent depth perception was achieved. A comparison of Examples 3 to 5 with Examples 1 and 2 confirmed that when the S value calculated by the above-mentioned formula (1) was 5.0 × 10 ８ ~5.0 x 10 ９ It has been confirmed that when the thickness is 100 nm, the in-plane light emission uniformity is superior and the sense of depth is superior.

[0099] 10a, 10b, 10c Lighting fixture 12 Diffusion plate 14 Fixture body 16 Transmitting plate 18 Cover 20a, 20b, 20c LED light source (light source) 22 LED module

Claims

1. A lighting device comprising a light source and a diffusion plate that diffuses light from the light source, the diffusion plate comprising cellulose nanofibers.

2. The lighting device according to claim 1, wherein the porosity of the diffusion plate is 90% or more.

3. The lighting device according to claim 1 or 2, wherein the thickness of the diffusion plate is 3 mm or more.

4. A lighting device as described in claim 1 or 2, wherein the content of the cellulose nanofibers relative to the total mass of the diffusion plate is 70 mass% or more.

5. A lighting device according to claim 1 or 2, wherein the fiber diameter of the cellulose nanofibers is 3 to 30 nm.

6. The S value calculated by the following formula (1) is 5.0 x 10 ８ ~5.0 x 10 ９ 3. The lighting device according to claim 1, wherein S=td ６ In formula (1), d represents the fiber diameter of the cellulose nanofiber, and the unit of d is nm. In formula (1), t represents the thickness of the diffusion plate, and the unit of t is mm.

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