Light diffuser, lighting fixture, and method for manufacturing light diffuser

Abstract

Provided are a light diffuser, a lighting fixture, and a method for manufacturing such a light diffuser, wherein the brightness or color tone of the light diffuser's exit surface is controlled. The light diffuser (100) comprises: an incident surface (121) for first light (Li) to be incident; a light scattering portion (110) comprising light scattering particles (112) present in a medium (111) for generating scattered light by guiding the incident first light and scattering the light by the light scattering particles; and an exit surface (122) for emitting the scattered light, wherein the concentration distribution of the light scattering particles in the light scattering portion increases continuously or discontinuously in a nonlinear manner in accordance with the distance from the incident end in the light guiding direction of the first light in the light scattering portion.

Description

Technical Field

[0001] The present invention relates to a light diffuser, a lighting fixture, and a method for manufacturing the light diffuser. Background Art

[0002] In backlight applications, lighting applications, etc., there is a known technology for extracting scattered light from incident light by utilizing the scattering effect of light scattering particles. For example, Patent Document 1 describes a light guide plate formed of a transparent material into a plate shape and having light scattering particles diffused therein as an example of a light guide plate for backlight applications. The light guide plate described in Patent Document 1 emits light introduced into the interior of the light guide plate from a light source facing its end face from an emission surface.

[0003] In this light guide plate, in order to make the intensity of light emitted from the light guide plate the same in all parts of the emitting surface of the light guide plate, the number of light scattering particles diffused in the transparent material per unit area is greater in areas where the intensity of light introduced from the light source is weaker.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2007-273090 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The light guide plate is an embodiment of a light diffuser, and the light guide method of the light diffuser, which guides light from a light source facing the end surface into the diffuser and emits light from an emission surface formed on the main surface, as described in Patent Document 1, is called an edge-incident method. By using a light diffuser using the edge-incident method, a display device and a lighting device using the light diffuser can be made thinner.

[0009] However, Patent Document 1 does not disclose a specific example of what kind of particle concentration distribution is suitable for target brightness and target product size (length and thickness).

[0010] For example, when the technology described in Patent Document 1 is applied to a lighting device that uses Rayleigh scattering to simulate a blue sky, it is difficult to obtain uniform brightness and color tone if the number of light scattering particles per unit area is controlled by only considering the intensity of light introduced into the light diffuser.

[0011] In recent years, display devices and lighting devices have been required to have larger areas. In the case of edge incidence, the light guide distance in the diffuser plate becomes longer, so that uneven brightness and uneven color are likely to become problems.

[0012] In response to the above-mentioned problems, an index and a mounting technique that can easily control the brightness or color tone of the light output surface of the light diffuser are desired.

[0013] Therefore, an object of the present invention is to provide a light diffuser, a lighting fixture, and a method for manufacturing such a light diffuser, which improves the uniformity of the brightness or hue of the light diffuser's output surface and controls the brightness or hue of the light diffuser's output surface.

[0014] Means for solving problems

[0015] One embodiment of the light diffuser of the present invention is a light diffuser that allows first light to be incident and allows scattered light to be emitted, and is characterized in that the light diffuser has: an incident surface that allows the first light to be incident; a light scattering portion that includes light scattering particles present in a medium, and generates scattered light by guiding the incident first light and scattering it using the light scattering particles; and an exit surface that allows the scattered light to be emitted, and the concentration distribution of the light scattering particles in the light diffuser is continuously or discontinuously increased in a nonlinear manner corresponding to the distance from the incident end in the guiding direction of the first light.

[0016] In addition, one embodiment of the light diffuser of the present invention can also be a light diffuser that allows the first light to be incident and allows the scattered light to be emitted, characterized in that the light diffuser has: an incident surface, which allows the first light to be incident; a light scattering portion, which contains light scattering particles present in a medium, and generates scattered light by guiding the incident first light and scattering it using the light scattering particles; a light transmitting portion, which does not contain light scattering particles in the medium; and an output surface, which allows the scattered light to be emitted, the light guiding portion being formed by the light scattering portion and the light transmitting portion connected to the light scattering portion, the light guiding portion functions as a light guiding path for the first light, and the light scattering portion is a stacked structure of two or more diffusion films with different lengths in the light guiding direction of the first light, or a structure in which the particle concentration in the medium is substantially constant and has a surface with a specified curved surface shape or step difference.

[0017] Furthermore, one aspect of the lighting fixture of the present invention includes: a light source that emits the first light; and the above-mentioned light diffuser.

[0018] In addition, one embodiment of the method for manufacturing a light diffuser of the present invention is a method for manufacturing a light diffuser, the light diffuser comprising: an incident surface for incident first light; a light scattering portion comprising light scattering particles present in a medium, generating scattered light by guiding the incident first light and scattering it using the light scattering particles; and an exit surface for emitting the scattered light, the method for manufacturing the light diffuser being characterized in that it comprises: a first step of dispersing light scattering particles in a material of the medium to form a prefabricated light scattering portion of a prescribed shape; and a second step of joining a plurality of prefabricated light scattering portions of a prescribed shape formed in the first step to form the light scattering portion, wherein in the second step, a plurality of prefabricated light scattering portions having different concentrations of light scattering particles in the medium and different lengths in the guiding direction of the first light are joined to form the light scattering portion.

[0019] Effects of the Invention

[0020] According to the present invention, it is possible to provide a light diffuser, a lighting fixture, and a method for manufacturing such a light diffuser in which the brightness or color tone of the light emission surface of the light diffuser is controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a cross-sectional view showing an example of the light diffuser 100 according to Embodiment 1.

[0022] Figure 2 (a) is an explanatory diagram showing examples of the light Li, the light Ls, and the light Lt, and (b) is an explanatory diagram showing an example of the generation principle of the light Ls in the light diffuser 100 .

[0023] Figure 3 This is a cross-sectional view showing a structural example of the light diffuser 100 according to Embodiment 1.

[0024] Figure 4 1 is an explanatory diagram showing an example of a model of the light diffuser 100 for deriving a fractional function to which the concentration distribution of light scattering particles conforms.

[0025] Figure 5 It is a perspective view showing a shape example of the light diffuser 100 .

[0026] Figure 6 (a) is an explanatory diagram showing an example of arrangement of the light source 10 with respect to the light diffuser 100 , and (b) is a schematic configuration diagram of the light source 10 .

[0027] Figure 7 This is an explanatory diagram showing an example of a method for manufacturing the light diffuser 100 according to the first embodiment.

[0028] Figure 8 This is an explanatory diagram showing another example of the method for manufacturing the light diffuser 100 according to the first embodiment.

[0029] Fig. 9 This is a cross-sectional view showing an example of the light diffuser 100 according to the second embodiment.

[0030] Fig.10 This is a cross-sectional view showing another example of the light diffuser 100 according to the second embodiment.

[0031] Fig.11 This is an explanatory diagram showing an example of a method for manufacturing the light diffuser 100 according to the second embodiment.

[0032] Fig.12 This is an explanatory diagram showing another example of the method for manufacturing the light diffuser 100 according to the second embodiment.

[0033] Fig.13 Graphs showing examples of changes in the concentration of light scattering particles in the diffuser 100 , changes in the intensity of the advancing light, and changes in the intensity of the scattered light with respect to the distance x.

[0034] Fig.14 Graphs showing examples of changes in the concentration of light scattering particles in the diffuser 100 , changes in the intensity of the advancing light, and changes in the intensity of the scattered light with respect to the distance x. DETAILED DESCRIPTION

[0035] Hereinafter, each embodiment will be described with reference to the accompanying drawings. In the following figures, the scales of the dimensions are sometimes different according to the constituent elements. In addition, in the following embodiments, for ease of description, the coordinate axes of the XYZ rectangular coordinate system are sometimes shown in each figure.

[0036] Implementation Method 1

[0037] Figure 1 This is a cross-sectional view showing an example of the light diffuser 100 according to Embodiment 1. Figure 1 The light diffuser 100 shown is a plate-shaped body having a rectangular cross-section and has substantially the same cross-section in the longitudinal direction. In addition, the light diffuser 100 is not limited to a plate-shaped body. The light diffuser 100 may also be, for example, a rod-shaped body. Here, the plate-shaped body is a shape having two main surfaces connected by side surfaces. In addition, the rod-shaped body is a shape of a cylinder having two bottom surfaces connected by one or more side surfaces. In addition, a rod is a general term for a cylinder. Hereinafter, in a rod-shaped body, regardless of the shape of the bottom surface, the side surface connected to the two bottom surfaces (in the case of a hollow cylinder, the outer surface of the side surface) is referred to as a main surface. In addition, in the following content, regardless of the shape of the light diffuser 100, the end surface constituting the end of the main surface is sometimes referred to as a "side surface of the light diffuser 100". In addition, the side surface of the light diffuser 100 includes the side surface of the plate shape and the bottom surface of the rod shape.

[0038] In the case of a plate-shaped or rod-shaped light diffuser, the main surface is mainly used as the exit surface, and the exit surface emits scattered light to the outside. In the following content, when one main surface is used as the exit surface in the plate shape, the one main surface is sometimes referred to as the first surface or the front surface (front surface), and the other main surface is referred to as the second surface or the back surface (back surface). In addition, when a portion of the area on the main surface (the side of the cylinder) is used as the exit surface in the rod shape, the portion of the area is sometimes referred to as the first surface or the front surface, and the area on the opposite side thereof (more specifically, the area on the main surface) is referred to as the second surface or the back surface. In addition, in the case of a plate shape, a portion of the area on the main surface can also be used as the exit surface, in which case the first surface or the front surface refers to the portion of the area, and the second surface or the back refers to the area on the opposite side of the portion of the area (more specifically, the area on the main surface).

[0039] In addition, the first surface and the second surface are not limited to flat surfaces, for example, they may be curved or inclined relative to the opposite surface. In other words, the first surface and the second surface may also be curved surfaces or inclined surfaces, or may also be a flat surface and a curved surface or inclined surface or a combination of both. In the following embodiments, the normal direction of the exit surface is regarded as the emission direction of the scattered light in the light diffuser 100. In addition, in the case where the exit surface includes a surface other than a flat surface, the normal direction at the center of the exit surface or the normal direction of the tangent plane at the center of the exit surface may also be regarded as the emission direction of the scattered light in the light diffuser 100. In addition, in the case where the exit surface is formed on the side surface of a cylinder, and the normal direction of the exit surface is not determined to be one direction, any one of the multiple normal directions may also be regarded as the emission direction of the scattered light in the light diffuser 100.

[0040] The light diffuser 100 is a structure including an incident surface 121 and an outgoing surface 122. In addition, the light diffuser 100 includes a light scattering layer 110. In addition, the light scattering layer 110 is also called a light scattering portion. In addition, the light diffuser 100 may also include a back surface 123. Figure 1 In the example shown, the main surface in the -Y axis direction is represented as the exit surface 122, and the main surface in the +Y axis direction is represented as the back surface 123, but, for example, the main surface in the +Y axis direction in the figure can be used as the exit surface 122, the main surface in the -Y axis direction in the figure can be used as the back surface 123, or the main surfaces in the ±Y axis directions can be used as the exit surface 122.

[0041] The light diffuser 100 allows light to enter from the incident surface 121 , guides the incident light inside, scatters the light, and takes it out from the emission surface 122 .

[0042] The incident surface 121 is incident on, for example, light emitted by a light source. The incident surface 121 is formed, for example, at an end of the light diffuser 100. The exit surface 122 allows scattered light generated, for example, in the light diffuser 100 to be emitted. In addition, the exit surface 122 can also allow light guided in the light diffuser 100 to be emitted. The exit surface 122 is formed, for example, on the surface of the light diffuser 100. The exit surface 122 can also be formed, for example, in a partial area of ​​the surface of the light diffuser 100.

[0043] In the following content, an example of an edge-incident light diffuser 100 is shown in which light is incident from the end face on the -Z axis side relative to the main surface, the incident light is guided in the +Z axis direction, and the scattered light is emitted in the -Y axis direction. However, the guiding direction of the incident light and the emission direction of the scattered light in the light diffuser 100 are not limited to this example.

[0044] Hereinafter, light incident on the light diffuser 100 is sometimes referred to as light Li. In addition, scattered light emitted from the light diffuser 100 is sometimes referred to as light Ls or scattered light Ls. In addition, light guided within the light diffuser 100 is sometimes referred to as light Lt or propagated light Lt. In addition, in this specification, light generated by scattering is referred to as "scattered light", and scattered light taken out is also referred to as diffused light. In addition, "light guiding" means causing light incident on a certain medium to propagate within the medium according to a prescribed optical path. In addition, light Li is also referred to as the first light. In this case, light Lt is the first light incident on the light diffuser 100, which is equivalent to light guided within the light diffuser 100.

[0045] Figure 2 (a) is an explanatory diagram showing examples of light Li, light Ls, and light Lt. Figure 2 (b) is an explanatory diagram showing an example of the principle of generating light Ls in the light diffuser 100. Figure 2 As shown in (a) and (b) of FIG. 1 , the light diffuser 100 allows the light Li emitted from the light source 10 to enter from the incident surface 121, guides the incident light Li as light Lt, and emits the scattered light Ls generated by the scattering effect of the light scattering layer 110 from the emission surface 122. Figure 2 As shown in (a) and (b) of FIG. 1 , the exit surface 122 from which the scattered light Ls is emitted is not limited to one. For example, the scattered light Ls may be emitted from the surface 122a and the surface 122b on the back side of the surface 122a. Hereinafter, a layer that functions as a light guide in the light diffuser 100, such as the light scattering layer 110 of the present embodiment, is sometimes referred to as a light guide portion, and the light guide guides the incident light Li as light Lt.

[0046] In addition, the light Lt may be light that travels from the incident end (incident surface 121) in the +Z axis direction to the end portion on the opposite side of the incident end in the light diffuser 100. Figure 2 As shown in (b), the light Lt may be guided by repeatedly reflecting on the surface of the light diffuser 100 (in this example, the surfaces 122a and 122b). The reflection here may be, for example, total reflection. Figure 2 As shown in (b), the light Ls is generated when, for example, the incident light Li is scattered by the light scattering particles 112 and the like included in the light scattering layer 110 in the process of being guided as the light Lt.

[0047] The light scattering layer 110 is a layer that exhibits a predetermined scattering energy to the light Lt. The light scattering layer 110 includes, for example, a substrate (medium) 111 and light scattering particles 112. The scattering energy is not particularly limited in detail as long as it can scatter the light introduced into the interior. In addition, the scattering energy includes reflection and refraction. The light scattering layer 110 may also be a layer in which spherical particles as light scattering particles 112 are dispersed in the substrate 111.

[0048] The substrate 111 can be any material that allows light to pass through. The substrate 111 is, for example, a solid. The substrate 111 can be, for example, a thermoplastic resin such as polycarbonate resin, polyarylate resin, polyethylene terephthalate resin, polyamide resin, polystyrene resin, polymethacryloyl styrene resin, polyacrylonitrile-styrene resin, polymethyl methacrylate resin, polymethylpentene resin, cyclic olefin resin, polyphenylene sulfide sulfone resin, polysulfone resin, polyether sulfone resin, polyamide-imide resin, or polyphenylene ether imide resin. In addition, the substrate 111 can also be a thermosetting resin such as epoxy resin, polyurethane resin, silicone resin, polyimide resin, etc. In addition, it can also be a photopolymerizable resin such as urethane acrylate resin, epoxy acrylate resin, acrylic acrylate resin, polyester acrylate resin, alicyclic epoxy resin, or glycidyl epoxy resin. In addition, the substrate 111 is not limited to a solid, and can also be a liquid, a liquid crystal, or an ionic fluid.

[0049] The light scattering particles 112 may be particles that generate at least one of reflection and refraction of light. The light scattering particles 112 may be inorganic particles such as zinc oxide, aluminum oxide, titanium oxide, zirconium oxide, silicon oxide, cerium oxide, etc. as inorganic oxides. In addition, the light scattering particles 112 may be organic particles such as acrylic resin, polystyrene resin, melamine resin, polyamide resin, etc. In addition, the light scattering particles 112 may be inorganic-organic particles such as silicone-acrylic composite particles.

[0050] Alternatively, the light scattering layer 110 may be an organic-inorganic hybrid resin such as a hybrid material of a resin and an inorganic oxide. In this case, the light scattering particles 112 may be an inorganic oxide generated by sol-gel curing or the like based on the substrate 111 .

[0051] The light scattering particles 112 are, for example, spherical. The light scattering particles 112 are, for example, true spherical. In addition, the light scattering particles 112 may be, for example, ellipsoidal. In addition, the light scattering particles 112 may be a shape in which a part of a sphere is given a concave-convex shape. In addition, the light scattering particles 112 may be hollow. The light scattering particles 112 may be, for example, hollow spherical particles.

[0052] In addition, the light scattering particles 112 may also be nanoparticles having a size (primary particle size) of the nanometer [nm] level. In this case, the scattered light Ls simulating the blue sky can be extracted by utilizing the Rayleigh scattering generated by the light scattering particles 112. That is, the scattered light Ls having a higher correlated color temperature than the correlated color temperature of the light Li as the incident light can be extracted. Nanoparticles generally refer to particles with a size of 1nm to several hundred nm, and the size of the light scattering particles 112 may also be 1nm to 990nm. In addition, in the use of simulating the blue sky, the size of the light scattering particles 112 is preferably 30nm to 500nm, more preferably 50nm to 350nm, and further preferably 60nm to 150nm.

[0053] In addition, in the light diffuser 100, the light scattering particles 112 may also be distributed so that the longer the distance from the incident end in the light guiding direction of the light Lt, the higher the concentration. More specifically, the light scattering particles 112 are preferably distributed so that their concentration increases continuously or discontinuously relative to the distance from the incident end. At this time, the increasing tendency of the concentration distribution of the particles is preferably not a simple increase but a nonlinear one. In other words, the light scattering particles 112 are preferably distributed so that their concentration increases continuously or discontinuously relative to the distance from the incident end in a nonlinear manner. Here, the increasing tendency of the concentration distribution may be an exponential function relationship or may follow the fractional function shown below. That is, the light scattering particles 112 may also be distributed so that the concentration in the light diffuser 100 increases continuously or discontinuously relative to the distance from the incident end in an exponential function relationship or by following a prescribed fractional function. By having such a particle concentration distribution in the light diffuser 100, the uniformity of the brightness and hue within the exit surface can be improved.

[0054] As a method for easily implementing such a particle concentration distribution, for example, Figure 3As shown, the light scattering layer 110 may also be integrated by joining a plurality of light scattering layers 1101 (e.g., light scattering layers 1101a to 1101d). In this case, sometimes there is a joining surface 131 between the light scattering layer 1101 and other light scattering layers 1101, and the method for forming the joining surface 131 is not particularly limited. The joining surface 131 may also be formed by, for example, joining the light scattering layers 1101 to each other using an adhesive or thermal fusion. The light scattering layer 1101 is also referred to as the second light scattering portion, for example.

[0055] An example of the adhesive is a solvent-type adhesive (for example, an adhesive produced by Acrisund Co., Ltd.) When a solvent-type adhesive is used, sufficient bonding can be achieved by leaving the adhesive at room temperature for only about 1 to 2 minutes, but it is more preferable to leave the adhesive for 24 hours.

[0056] At this time, the light scattering particles 112 in each light scattering layer 1101 may be dispersed uniformly or non-uniformly. The region including the bonding surfaces 131 of the light scattering layers 1101 is set to a range that does not significantly differ in particle concentration and thus impairs the uniformity of brightness.

[0057] When the light scattering layer 110 is composed of a plurality of light scattering layers 1101 with different particle concentrations, there is no particular limitation on the arrangement of the plurality of light scattering layers 1101 (the configuration in the light guiding direction of the light Lt). Therefore, the number and configuration of the light scattering layers 1101 can be freely determined according to the distribution of the target brightness and the distribution of the target hue. For the purpose of improving the uniformity of the brightness and hue in the emission surface, as mentioned above, it is preferred that the plurality of light scattering layers 1101 are successively configured so that the concentration n [individuals / m 3 ] is continuously or discontinuously increased in a nonlinear manner according to the distance x from the incident end in the light guiding direction of the light Lt. The nonlinearity here can be, for example, an exponential function relationship, or can follow a prescribed fractional function.

[0058] Here, the fractional function can also be expressed by the following formula (1).

[0059] [Mathematical formula 1]

[0060]

[0061] In the formula (1), n(x) represents the concentration of the light scattering particles 112 in the light diffuser 100 at a distance x [m] [particles / m 3 ]. In addition, a, b, and c are constants as shown below. That is, let r be the ratio of the scattered light intensity S0 at the incident end to the incident light intensity I0, S0 / I0, and q be the cross-sectional area [m 2] (More specifically, it is the projected cross-sectional area of ​​the light scattering particles 112 when viewed from the light guiding direction of the light Lt. Figure 2 In the example of , where q is the XY cross-sectional area of ​​the light scattering particle 112, p is the scattering probability of the light scattering particle 112, and is a constant represented by a=r, b=1, and c=2r / (q×p). In addition, q×p is also referred to as the scattering cross-sectional area of ​​the light scattering particle 112.

[0062] In addition, the symbol D in the figure represents the length of the light diffuser 100 (more specifically, the length of the light diffuser 100 in the light guiding direction of the light Lt), and the symbol H represents the thickness of the light diffuser 100 (more specifically, the length of the light diffuser 100 in the direction perpendicular to the light guiding direction of the light Lt. In addition, in this example, it is the length of the diffuser 100 in the normal direction of the emission surface). When formula (1) is expressed by r, q, and p, the following formula (2) is obtained.

[0063] [Mathematical formula 2]

[0064]

[0065] Figure 4 : is a model diagram of the light diffuser 100 used to derive the above-mentioned formula. Figure 4 In the model shown, the intensity S(x) of scattered light directed toward the lower side (-Y axis direction in the figure) of the light diffuser 100 is determined by the following formula (3).

[0066] [Mathematical formula 3]

[0067]

[0068] Here, the fifth term ×(1 / 2) on the right side is intended to extract only the scattered light Ls traveling downward among the scattered light Ls traveling in the vertical direction, but the fifth term may be omitted when the scattered light Ls traveling upward is also extracted using a reflector, etc. In this case, the constant c mentioned above may be rewritten as c=r / (q×p).

[0069] The intensity I(x) of the light (forward light) advancing in the light-guiding direction is scattered and reduced during the propagation to the position of distance x. The slope of I(x) is proportional to the intensity of the forward light itself. Under this premise, in order to make it constant at S(x) = S0, the forward light I(x) only needs to be scattered at a constant ratio when advancing in the light-guiding direction. That is, it only needs to satisfy the following formula (4).

[0070] [Formula 4]

[0071] I(x)=I0-2S0x…(4)

[0072] The following equation (5) is derived from equations (3) and (4), and further equation (6) is derived.

[0073] [Mathematical formula 5]

[0074]

[0075]

[0076] Here, when r=S0 / I0 is assumed, the above-mentioned formula (2) is derived from the formula (6).

[0077] In addition, the above-mentioned formula (1) is only an example, and the concentration distribution of the light scattering particles 112 in the light diffuser 100 may also satisfy any of the following conditions 1 to 3. In the following, for example, if the second condition or the third condition is satisfied, the concentration distribution of the light scattering particles 112 in the light diffuser 100 may be regarded as increasing continuously or discontinuously in an exponential function relationship with respect to the distance x. In addition, if the third condition is satisfied, the concentration of the light scattering particles 112 in the light diffuser 100 may be regarded as increasing continuously or discontinuously following the fractional function shown in formula (1).

[0078] (condition)

[0079] 1. The concentration n of the light scattering particles 112 increases as the distance x increases. In other words, the light scattering layer 110 may also satisfy the following formula (7). In addition, as described above, it is more preferable that the concentration n increases nonlinearly.

[0080] [Mathematical formula 6]

[0081]

[0082] 2. The slope of n(x) increases as x increases. In other words, the light scattering layer 110 may also satisfy the following formula (8).

[0083] [Formula 7]

[0084]

[0085] 3. The slope of n(x) is within a predetermined range. In other words, the light scattering layer 110 may satisfy the following formula (9).

[0086] [Mathematical formula 8]

[0087]

[0088] Here, α is a parameter representing the allowable range of the fractional function shown in formula (1) relative to the slope of n(x). Here, α is preferably a positive number less than 2. In addition, α can also be a constant of 0.5 to 1.5. When the third condition is satisfied, the concentration distribution n(x) can also be regarded as satisfying the fractional function shown in formula (1).

[0089] In the above example, the concentration distribution of the light scattering particles 112 in a certain medium becomes higher continuously or discontinuously according to the distance x, which means that the concentration of the light scattering particles 112 per unit volume in the light diffuser 100 becomes higher continuously or discontinuously according to the distance x. Here, the unit of length in the unit volume can be set arbitrarily, and can also be, for example, millimeter level. In addition, the volume equivalent to the unit weight (for example, 1g) can also be used as the unit volume. In addition, the concentration distribution of the light scattering particles 112 in the above-mentioned light diffuser 100 mainly refers to the in-plane distribution of the particle concentration when observed from the exit surface side. Therefore, the length in the thickness direction in the unit volume can also be used as the thickness H (length in the thickness direction) of the light diffuser 100 (or the light guiding portion).

[0090] For example, in Figure 3 In the case of the example shown, the concentration per unit volume of the light scattering particles 112 is from high to low in the order of the light scattering layers 1101d, 1101c, 1101b, and 1101a. That is, the particle concentration of the light scattering layer 1101a is the lowest, the particle concentration of the light scattering layer 1101b is higher than the particle concentration of the light scattering layer 1101a, the particle concentration of the light scattering layer 1101c is higher than the particle concentration of the light scattering layer 1101b, and the particle concentration of the light scattering layer 1101d is the highest. In other words, the plurality of light scattering layers 1101 constituting the light scattering layer 110 are configured so that the particle concentration gradually (or stepwise) becomes higher in the light guiding direction of the light Lt.

[0091] In addition, as a method for measuring the particle concentration or the distribution of the particle concentration in the light diffuser 100 or in a certain medium, the following examples can be cited. As a first example, if the light scattering particles 112 are inorganic particles, the inorganic element analysis method can also be used to quantitatively measure the ratio (mass %) of the elements contained in the composition of the light scattering particles 112 (for example, if it is a silica particle, it is Si) in the sample, and the number and concentration of the light scattering particles 112 in the sample are obtained based on the ratio. As an inorganic element analysis method, ICP-AES (ICP-Atomic Emission Spectroscopy) or ICP-OES (ICP-Optical Emission Spectrometry) using fused coupled plasma (Inductively Coupled Plasma: ICP (Inductively Coupled Plasma)) can be cited. In addition, when obtaining the number and concentration of the light scattering particles 112 in the sample, the bonding state of the elements in the sample, the shape and size of the particles in the sample obtained by other analysis methods can also be used. The bonding state of the elements in the sample can be analyzed using, for example, X-ray Photograph Spectroscopy (XPS) and high energy resolution Auger Electron Spectroscopy (AES). The shape and size of the particles in the sample can be analyzed using, for example, a scanning electron microscope (SEM) and a transmission electron microscope (TEM).

[0092] As a second example, it is also possible to incident laser light or other highly straight light on the light diffuser 100 in the thickness direction, and to measure the intensity of the light intensity of the straight transmitted light emitted from the light diffuser 100 at multiple positions in the plane when observed from the exit surface side of the light diffuser 100, and to infer the particle concentration or particle concentration distribution in the light diffuser 100 based on the light intensity distribution of the straight transmitted light obtained by the intensity measurement. The light intensity of the straight transmitted light emitted from the light diffuser 100 varies according to the scattering probability of the light diffuser 100 at that position. Here, the scattering probability of the light diffuser 100 is a parameter having a prescribed correlation with the concentration (number per unit volume) of the light diffusion particles 112. Therefore, if such a correlation is used, the in-plane distribution of the light intensity of the straight transmitted light obtained by the measurement can be converted into the particle concentration or particle distribution in the plane. As an example of the above correlation, a linear (linear function) can be cited, but it is not limited to this depending on the material used or the design concept (desired brightness, color tone).

[0093] In addition, the particle concentration distribution in the in-plane direction perpendicular to the light guiding direction is preferably uniformly dispersed, but slight distribution deviation may occur in the manufacturing process, so this is not limited to this.

[0094] In addition, the above-mentioned example of the concentration distribution of the light scattering particles 112 is a preferred example in the case where light is incident only from one end face of the light diffuser 100. Therefore, it is not limited to this in the case where light is incident from multiple end faces (for example, two opposite side faces, or three or more side faces including adjacent side faces, etc.). In such a case, since the light guide direction of the light Lt in the light diffuser 100 is more than two directions, for example, the above-mentioned example of the concentration distribution of the light scattering particles 112 can be applied to the light guide direction of the light incident from each incident end, and the result obtained by superimposing their in-plane distribution or slope when observed from the exit surface side is used as the final concentration distribution. Thus, the concentration of the light scattering particles 112 can be appropriately distributed relative to the distance x from all incident ends in all light guide directions of the light Lt. As an example, in the case where light is incident from two opposite ends, the concentration of the light scattering particles 112 is preferably distributed to be the highest near the central part, and the closer to the incident surface, the lower it is.

[0095] The above-mentioned example of the concentration distribution of the light scattering particles 112 is a preferred example for making the intensity of the scattered light Ls emitted from the emission surface 122 constant within the surface. Therefore, the use other than improving uniformity is not limited to this. Therefore, the light diffuser 100 can adopt any concentration distribution.

[0096] In addition, several preferred examples have been described so far regarding the concentration distribution of the light scattering particles 112 in the light diffuser 100 (more specifically, the light scattering layer 110 as the light guiding portion), but the above-mentioned concentration distribution or the increasing tendency of the concentration distribution may be directly regarded as the in-plane distribution or the increasing tendency of the in-plane distribution of the weight ratio (weight % of the element per unit volume) or the mass ratio (mass % of the element per unit volume) of the predetermined element constituting the light scattering particles 112 contained per unit volume in the light diffuser 100 (more specifically, the light scattering layer 110) when viewed from the emission surface side.

[0097] In addition, the light diffuser 100 is composed of, for example, a light scattering layer 110. In addition, the light diffuser 100 may also be a structure in which, for example, a plurality of light scattering layers 1101 are arranged along the light guiding direction of the light Lt. In addition, when there are multiple light guiding directions of the light Lt, it is preferably arranged along respective directions. In addition, the light diffuser 100 may also have an anti-reflection layer, an anti-fouling layer, a heat-insulating layer, and other functional layers in addition to one light scattering layer 110 or a plurality of light scattering layers 1101. In addition, the light diffuser 100 may also have a light-transmitting layer that does not exhibit scattering energy. In addition, the light-transmitting layer is also referred to as a light-transmitting portion. The light-transmitting layer may also be, for example, a transparent substrate. In this case, the light scattering layer 110 may also be formed on the transparent substrate. In addition, the light-transmitting layer may also be the light-transmitting layer 113 described later.

[0098] Furthermore, the light diffuser 100 and the light scattering layer 110 may be added with any reinforcing material or additive within a range that does not significantly impair the optical properties thereof.

[0099] As the example of reinforcement material, fibrous reinforcement material and plate-like reinforcement material can be cited. As the specific example of fibrous reinforcement material, carbon fiber, glass fiber, boron fiber, asbestos fiber, polyvinyl alcohol fiber, polyester fiber, acrylic fiber, fully aromatic polyamide fiber, polybenzoxazole fiber, polytetrafluoroethylene fiber, kenaf fiber, bamboo fiber, hemp fiber, bagasse fiber, high-strength polyethylene fiber, alumina fiber, silicon carbide fiber, potassium titanate fiber, brass fiber, stainless steel fiber, steel fiber, ceramic fiber, basalt fiber, sepiolite, attapulgite etc. can be cited. Fiber-like reinforcement material can also be used in combination with more than 2 kinds. In addition, silane coupling agent can also be used for surface treatment of fibrous reinforcement material. The cross section of fibrous reinforcement material is preferably circular, but as required, it can also be rectangular, elliptical (flat) and irregular cross sections in addition thereto.

[0100] As specific examples of plate-like reinforcement materials, talc, mica, sericite, glass flakes, plate-like calcium carbonate, plate-like aluminum hydroxide, graphite, kaolin, swelling layered silicate, etc. can be enumerated. Two or more plate-like reinforcement materials can also be used in combination. By adding plate-like reinforcement materials, dimensional stability can be improved.

[0101] In addition, examples of additives include impact resistance improving materials, antistatic agents, conductivity imparting agents, thermal conductive fillers, other resin components, heat stabilizers, light stabilizers, sliding properties improving materials, flame retardants, flame retardant aids, pigments, light absorbers, etc. Two or more additives may be used in combination.

[0102] Specific examples of impact-resistant improving materials include olefin polymers such as (ethylene and / or propylene)·α-olefin copolymers, (ethylene and / or propylene)·(α, β-unsaturated carboxylic acid and / or unsaturated carboxylic acid and / or unsaturated carboxylic acid ester) copolymers, and elastomers such as styrene elastomers. By adding impact-resistant improving materials, impact resistance and welding strength can be improved.

[0103] Specific examples of antistatic agents include anionic antistatic agents, cationic antistatic materials, nonionic antistatic agents, etc. Specific examples of conductivity imparting agents include carbon black, carbon fibers, metal fibers, etc. By adding antistatic agents and conductivity imparting agents, the surface intrinsic resistance value and volume intrinsic resistance value can be reduced.

[0104] Specific examples of the thermally conductive filler include talc, aluminum oxide, magnesium oxide, zinc oxide, magnesium carbonate, silicon carbide, aluminum nitride, boron nitride, silicon nitride, carbon, graphite, etc. By adding the thermally conductive filler, thermal conductivity can be improved.

[0105] Specific examples of other resin components include polyarylate resins, polycarbonate resins, polystyrene resins, acrylonitrile-styrene resins, acrylic resins, polyimide resins, polyetherimide resins, polyurea resins, epoxy resins, polyester resins, polyesterimide resins, polyurethane resins, polyphenyl sulfone, polysulfone, polyethylene, polypropylene, polyvinyl chloride, melamine resins, silicone resins, etc. By adding other resin components, heat resistance, strength, flexibility, etc. can be improved.

[0106] Specific examples of the heat stabilizer include hindered phenol compounds, phosphite compounds, hindered amine compounds, triazine compounds, sulfur compounds, etc. By adding a heat stabilizer, a decrease in molecular weight of the substrate 111 and degradation of color can be suppressed.

[0107] Specific examples of the light stabilizer include benzophenone compounds, benzotriazole compounds, salicylate compounds, hindered amine compounds, hindered phenol compounds, etc. By adding the light stabilizer, a decrease in the molecular weight of the substrate 111 due to ultraviolet rays or the like can be suppressed.

[0108] Specific examples of the sliding property improving material include fluororesins such as polytetrafluoroethylene, and silicones such as polydimethylsiloxane and fluorine-modified polydimethylsiloxane.

[0109] Examples of the flame retardant include bromine-containing flame retardants, nitrogen-containing flame retardants, phosphorus-containing flame retardants, nitrogen-containing-phosphorus-containing flame retardants, hydrated metal-based flame retardants, and inorganic-based flame retardants.

[0110] Specific examples of bromine-containing flame retardants include brominated polystyrene, polybrominated styrene, brominated polyphenylene ether, etc. Among them, in terms of the significant effect of improving flame retardancy, it is preferred to contain 40 to 80% by mass of bromine, and more preferably 50 to 70% by mass of bromine. These bromine-containing flame retardants are preferably used in combination with flame retardant aids such as antimony trioxide, antimony tetroxide, antimony pentoxide, sodium antimonate, tin oxide (IV), iron oxide (III), zinc oxide, and zinc borate.

[0111] Specific examples of the nitrogen-containing flame retardant include melamine compounds, salts of cyanuric acid or isocyanuric acid with a melamine compound, and salts of phosphoric acid or polyphosphoric acid with ammonia or a melamine compound.

[0112] Specific examples of the phosphorus-containing flame retardant include phosphoric acid ester compounds, phosphinates, and phosphinates.

[0113] Specific examples of nitrogen-phosphorus-containing flame retardants include adducts formed from melamine or its condensation product and phosphoric acid (melamine adducts), etc. Specific examples of phosphoric acid constituting the melamine adducts include orthophosphoric acid, phosphonic acid, phosphinic acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, and tetraphosphoric acid.

[0114] Specific examples of the hydrated metal flame retardant include aluminum hydroxide, boehmite, magnesium hydroxide, calcium hydroxide, and calcium aluminate.

[0115] Specific examples of the inorganic flame retardant include zinc borate and a mixture of zinc borate and other zinc salts.

[0116] Specific examples of the pigment include titanium oxide, zinc oxide, zinc sulfide, zinc sulfate, barium sulfate, calcium carbonate, aluminum oxide, and the like.

[0117] As specific examples of light absorbers, visible light absorbers, ultraviolet absorbers, etc. can be cited. By adding a light absorber, the hue of the scattered light Ls can be adjusted. For example, among visible light absorbers, by using a red absorber, the blue component of the scattered light can be emphasized in the application of simulating a blue sky. As a specific example of a red absorber, a visible light absorbing material FDB-001 (produced by Yamada Chemical Industry Co., Ltd.) can be cited.

[0118] Furthermore, a transmissive functional coating such as an antireflection coating, an antifouling coating, a heat shielding coating, or an abrasion resistant coating may be applied to at least any surface of the surface of the light diffuser 100 .

[0119] Figure 5 1 is a perspective view showing an example of the shape of the light diffuser 100. Figure 5 In the case of the plate shape shown, four surfaces other than the main surfaces 101a and 101b are side surfaces 102a, 102b, 102c, and 102d. The main surface 101a and the main surface 101b are opposite to each other. In addition, the side surface 102a and the side surface 102b are opposite to each other. In addition, the side surface 102c and the side surface 102d are opposite to each other.

[0120] The surface (especially the main surface) of the light diffuser 100 is preferably highly smooth, but sometimes fine scratches and fine bumps are generated during the manufacturing process, so it is not limited to this. In addition, in the case of intentionally making the light emitted from the light diffuser 100 diffuse, or forming fine bumps, it is not limited to this.

[0121] The light diffuser 100 of the present embodiment can be used as a component of a lighting fixture, for example. Figure 2 1 is a cross-sectional view of a lighting fixture 200 in which the light diffuser 100 is used. The lighting fixture 200 includes a light source 10 that emits light Li and a light diffuser 100 into which the light Li is incident and emits scattered light Ls. The lighting fixture 200 may also include a frame (not shown) that supports the light source 10 and the light diffuser 100.

[0122] The light source 10 emits light Li. The light source 10 may also be a light source that emits white light as the light Li. The light source 10 is, for example, an LED light source. Figure 6 (a) is an explanatory diagram showing an example of arrangement of the light source 10 with respect to the light diffuser 100, Figure 6 (b) is a schematic structural diagram of the light source 10. Figure 6 As shown in (a) and (b) of FIG. 1 , the light source 10 may include a substrate 11 and a plurality of light emitting elements 12 (eg, LED elements), and the plurality of light emitting elements 12 are arranged on the substrate 11 .

[0123] The light emitted by each light emitting element 12 may be the same color or different colors. The light emitted by each light emitting element 12 may be any color of red, green, and blue. Furthermore, the light source 10 as a whole may also include light emitting elements 12 of three colors: red, green, and blue.

[0124] In addition, the light emitted by each light emitting element 12 may be any color of white, green, and blue. Furthermore, the light source 10 as a whole may also include light emitting elements 12 of three colors, namely white, green, and blue. In addition, the light emitted by each light emitting element 12 may be any color of white, green, blue, and orange. Furthermore, the light source 10 as a whole may also include light emitting elements 12 of four colors, namely white, green, blue, and orange.

[0125] The light source 10 includes a light emitting surface 13 that emits light. The light emitting surface 13 is, for example, arranged opposite to an incident surface 121 formed at an end surface of an end portion constituting a main surface of the light diffuser 100. Here, the end surface of the end portion constituting the main surface of the light diffuser 100 includes a plate-shaped side surface and a rod-shaped bottom surface. For example, the light emitting surface 13 may also be arranged along the incident surface 121. In addition, for example, the light emitting surface 13 may also be arranged along the incident surface 121, and a plurality of light emitting surfaces may be arranged in the thickness direction of the light diffuser 100 (the Y-axis direction in the figure).

[0126] For example, the light emitting surface 13 and the side surface of the plate-shaped light diffuser 100 (for example, Figure 5 In this case, for example, Figure 6 As shown in (a) of FIG. 1 , the light source 10 (more specifically, the light emitting element 12 constituting the light source 10 ) may be arranged along the side surface of the plate-shaped light diffuser 100 . Figure 5 In the case of the example, the light source 10 may also be arranged, for example, along the side surface 102a of the light diffuser. In addition, the light source 10 may also be arranged, for example, along the side surfaces 102a and 102b of the light diffuser. In addition, the light source 10 may also be arranged, for example, along the side surfaces 102a, 102b, and 102c of the light diffuser. In addition, the light source 10 may also be arranged, for example, along the side surfaces 102a, 102b, 102c, and 102d of the light diffuser.

[0127] In addition, the light source 10 may be disposed along at least one of the side surfaces 102a, 102b, 102c, and 102d of the light diffuser. In addition, a plurality of light sources 10 may be disposed along at least one of the side surfaces 102a, 102b, 102c, and 102d of the light diffuser.

[0128] Next, a method for manufacturing the light diffuser 100 according to the present embodiment will be described. Figure 7 It is an explanatory diagram showing an example of a method for manufacturing the light diffuser 100 according to the present embodiment. Figure 7 The example shown is constructed by Figure 3 The method of manufacturing the light diffuser 100 having a desired particle concentration distribution is performed by bonding and integrating a plurality of resin molded bodies of a plurality of light scattering layers 1101 having different particle concentrations as shown.

[0129] In this example, first, a resin material (resin particles, etc.) in which light scattering particles 112 are dispersed in the same material as the base material 111 of each light scattering layer 1101 is prepared ( Figure 7 (a): particle dispersion step). Here, the material of the substrate 111 of each light scattering layer 1101 is preferably the same as that of the substrate 111 of other light scattering layers 1101, or a material having a refractive index in the wavelength band of the light Lt after molding that is substantially the same as that of the substrate 111 of other light scattering layers 1101.

[0130] This operation can be applied to known methods.For example, use a twin-shaft mixing extruder, while rotating the screw, while heating the thermoplastic resin of the material 41 of the base material 111 of each light scattering layer 1101 to a temperature above the melting point and becoming a molten state, adding light scattering particles 112 to the material (molten resin) obtained by the concentration of the regulation is extruded, and the material 42 (hereinafter, referred to as the particle-containing material 42) that is dispersed with the light scattering particles 112 is prepared thus. In this operation, the molten resin that can also be added with the light scattering particles 112 that are denser than the expected particle concentration is discharged from the mold and pulled with a twisted rope shape, and the cutting device that is called a granulator is used to cut off, and thus obtain resin particles.

[0131] Next, a plurality of resin molded bodies ( Figure 7 (b): Scattering layer forming step). This step can be applied by a known method. For example, a single-axis kneading extruder is used to melt-mix the thermoplastic resin as the material 41 of the substrate 111 and the particle-containing material 42 (resin particles) prepared in the particle dispersion step at a predetermined ratio, and extrusion molding is performed, thereby preparing a resin molded body of a desired shape in which light scattering particles 112 are dispersed in the substrate 111 at a target concentration. For example, when the molten resin is pulled out from the extruder, a T-die method is applied to pull the molten resin discharged from the discharge port of the T-die, thereby preparing a resin molded body in the shape of a plate with an arbitrary thickness in which light scattering particles 112 are dispersed in the substrate 111 at a target concentration. The T-die method is a method in which the molten resin is processed into a plate shape by extending it using a thinner linear gap (flat die) when it is extruded.

[0132] In addition, the particle dispersion process is not necessarily required, for example, the particle dispersion process may be simultaneously implemented in the scattering layer forming process. In this case, for example, the light scattering particles 112 may be supplied instead of the resin material in which the light scattering particles are dispersed as one of the materials supplied to the uniaxial kneading extruder. For example, the light scattering particles 112 and the thermoplastic resin as the material of the substrate 111 may be melt-mixed at a predetermined ratio using a uniaxial kneading extruder while being extruded to prepare a resin molded body of a desired shape in which the light scattering particles 112 are dispersed at a target concentration in the substrate 111.

[0133] In addition, the scattering layer forming step is performed in accordance with the number of light scattering layers 1101 constituting the light scattering layer 110. In this case, the target concentration in each scattering layer forming step can be set to the target concentration in the corresponding light scattering layer 1101. By changing the mixing ratio of the material of the substrate 111 and the light scattering particles, it is possible to prepare light scattering layers 1101 having various particle concentrations (for example, Figure 3 The resin molded body prepared in the above scattering layer forming step is also called a preliminary light scattering portion.

[0134] Next, the plurality of resin molded bodies (light scattering layers 1101) having different particle concentrations prepared in this manner are joined and integrated ( Figure 7 (c) joining process). This process can be applied by a known method, for example, using an adhesive, and joining and integrating the plurality of resin molded bodies prepared in the scattering layer forming process in an order in which the particle concentration increases as the distance from the incident end increases. At this time, the light scattering layer 1101 can also be configured so that the variation distribution of the particle concentration between the plurality of light scattering layers 1101 increases in a nonlinear manner corresponding to the distance from the incident end in the light guiding direction of the light Lt. As a method of joining, for example, it is also possible to join by using an adhesive 43 to bond the surfaces to be joined to each other. In addition, it is also possible to heat and melt the surfaces to be joined to each other and make them closely fit after becoming a molten state, and then cool them to join. In addition, in the joining process, it is preferred to use any of these two methods to join, but methods other than these methods can also be applied.

[0135] Based on the above, it is possible to form a light scattering layer 110 which is a bonded body of a plurality of resin molded bodies and a light diffuser 100 composed of such a light scattering layer 110 (see Figure 7 (d)). In addition, Figure 7 In (d), the bonding surface 131 is shown between the light scattering layers 1101 and the light scattering layers 1101. However, when fusion bonding is performed, the bonding surface 131 may not be clearly present.

[0136] In addition, when the light diffuser 100 has a functional layer in addition to the light scattering layer 110, for example, Figure 7 The light scattering layer 110 formed in the bonding step (c) is stacked with other functional layers.

[0137] In addition, in the above example, the plurality of resin molded bodies are joined in the order in which the particle concentration increases as the distance from the incident end increases, but the arrangement order of the resin molded bodies is not limited thereto. As long as the target particle concentration distribution is followed, the arrangement order of the resin molded bodies is not particularly limited. For example, in the light diffuser 100, the resin molded bodies may be arranged so that the concentration of the light scattering particles 112 is the highest near the central portion as described above, and the concentration of the light scattering particles 112 is lower as it is closer to the incident end.

[0138] also, Figure 8 This is an explanatory diagram showing another example of the method for manufacturing the light diffuser 100 according to the present embodiment. Figure 8 The example shown is a method of manufacturing a light diffuser 100 having one light scattering layer 110 in which the particle concentration in the layer changes continuously.

[0139] exist Figure 8 In the method shown, the particle dispersing step is performed in the scattering layer forming step, and the concentration of the light scattering particles 112 added to the material of the base material 111 of the light scattering layer 110 is changed over time.

[0140] As such a scattering layer forming process, for example, a molten resin obtained by melting a thermoplastic resin as a base material 111 of the light scattering layer 110 is supplied to an extruder 53 such as a uniaxial kneading extruder using a resin material supply device 51A, and light scattering particles 112 are supplied using a weight type powder and granule supply device 51B. At this time, the weight type powder and granule supply device 51B changes the supply amount of the light scattering particles 112 with time. In this way, by performing extrusion molding while changing the supply amount of the light scattering particles 112 supplied to the extruder 53 with time, a resin molded body of an arbitrary shape in which the concentration of the added particles in the base material 111 changes along the extrusion direction can be prepared. For example, by using a T-die 54 and a traction roller 55 to haul the molten resin extruded from the extruder 53, a resin molded body of a plate shape having an arbitrary thickness in which the concentration of the added particles in the base material 111 changes along the extrusion direction can be prepared.

[0141] like Figure 8As shown in (a), the light scattering layer 110 constituting the plurality of light diffusers 100 can also be formed by a single scattering layer forming step. In this case, the range of the desired concentration distribution can be cut out from the prepared resin molded body using cutting machines 56a, 56b, etc. Figure 8 In (a), the cutter 56a is a cutter that cuts the resin molded body in a direction parallel to the paper surface, and the cutter 56b is a cutter that cuts the resin molded body in a direction perpendicular to the paper surface.

[0142] Figure 8 (b) is an explanatory diagram showing an example of a change in the supply amount of the light scattering particles 112 (referred to as component (B) in the figure). For example, in the scattering layer forming step of this example, by cutting the light scattering particles 112 used in Figure 8 The range of the resin molded body formed by the light scattering particles 112 supplied during the time period surrounded by the dotted line (1) in (b) (for example, Figure 8 The range enclosed by the dotted line (1) of (a) can be cut out Figure 8 Similarly, by cutting the light diffuser 100 (1) used in Figure 8 The range of the resin molded body formed by the light scattering particles 112 supplied during the time period surrounded by the dotted line (2) in (b) (for example, Figure 8 The range enclosed by the dotted line (2) of (a) can be cut out Figure 8 (c) light diffuser 100(2). In addition, if the light guiding directions of the light diffuser 100(1) and the light diffuser 100(2) are reversed, it can be said that the light diffuser 100(1) and the light diffuser 100(2) are light diffusers 100 having the same particle concentration distribution. In this way, the addition amount corresponding to the particle concentration distribution in one light scattering layer 110 can be repeatedly changed while the direction of change is alternately reversed, thereby forming a plurality of light scattering layers 110 constituting a plurality of light diffusers 100 in a single scattering layer forming step. In addition, in the case of a concentration distribution in which the particle concentration near the central portion is high and the particle concentration decreases as it approaches the incident end, the addition amount corresponding to the particle concentration distribution in one light scattering layer 110 can be repeatedly changed without reversing the direction of change (for example, including Figure 8 In either case, it is sufficient to cut off the range with the desired concentration distribution. In addition, when repeatedly changing the amount of addition corresponding to the particle concentration distribution in one light scattering layer 110, a predetermined buffer area (an area for transferring from distribution (1) to distribution (2)) may be provided before transferring to the next amount of addition. Then, when cutting out the light diffuser 100, the buffer area may be removed for cutting out.

[0143] In addition, the above example is an example of using a thermoplastic resin as the material of the substrate 111, but a thermosetting resin can also be used as the material of the substrate 111. In the case of using a thermosetting resin as the material of the substrate 111, first, the light scattering particles 112 are dispersed in the resin before curing to prepare a particle dispersion (particle dispersion process). Next, the resin before thermosetting as the material of the substrate 111 is mixed with the prepared particle dispersion while flowing into the mold (mixing process). At this time, by changing the ratio of the two mixed over time, the particle concentration can be changed along the direction of change of the inflow position into the mold. Then, by applying heat to the particle-containing resin material that has entered the mold, a resin molded body of a desired shape can be prepared.

[0144] As described above, according to the present embodiment, the brightness or hue of the light output surface of the light diffuser can be easily controlled, and the particle concentration distribution for realizing the brightness or hue of such an output surface can be easily implemented, thereby making it possible to easily manufacture a light diffuser with controlled brightness or hue of the output surface and a device using the light diffuser.

[0145] Implementation Method 2

[0146] Fig. 9 (a) is a cross-sectional view showing an example of the light diffuser 100 according to Embodiment 2. Fig. 9 (b) is given by Fig. 9 An enlarged view of a main part of the area surrounded by the dotted line in (a). Fig. 9 The light diffuser 100 shown includes an incident surface 121 and an outgoing surface 122 similarly to Embodiment 1. In addition, the light diffuser 100 includes a light scattering layer 110. In addition, the light diffuser 100 may include a back surface 123.

[0147] In addition, Fig. 9 In the example shown, the main surface in the -Y axis direction is represented as the exit surface 122, and the main surface in the +Y axis direction is represented as the back surface 123, but, for example, the main surface in the +Y axis direction in the figure can be used as the exit surface 122, the main surface in the -Y axis direction in the figure can be used as the back surface 123, or the main surfaces in the ±Y axis directions can be used as the exit surface 122.

[0148] Hereinafter, the parts different from the first embodiment will be mainly described.

[0149] In the first embodiment, the following example is mainly described: while the thickness of the light scattering layer 110 is kept substantially uniform, the particle concentration in the light scattering layer 110 is changed in accordance with the distance from the incident end, thereby making the particle concentration in the light diffuser 100 have an in-plane distribution when viewed from the exit surface side. In contrast, in the present embodiment, the following example is mainly described: while the particle concentration in the light scattering layer 110 is kept substantially uniform, the thickness of the light scattering layer 110 is changed in accordance with the distance from the incident end, thereby making the particle concentration in the light diffuser 100 have an in-plane distribution when viewed from the exit surface side. In addition, the first embodiment and the second embodiment can be combined to change the particle concentration in the light scattering layer 110 in accordance with the distance from the incident end, and change the thickness (length in the normal direction of the exit surface) of the light scattering layer 110 in accordance with the distance from the incident end, so as to more freely control the in-plane distribution of the particle concentration in the light diffuser 100.

[0150] The light diffuser 100 includes a single light scattering layer 110 or a plurality of light scattering layers 110 having different thicknesses (lengths in the Y-axis direction in the figure) depending on the distance from the incident end.

[0151] For example, the light diffuser 100 may also have Fig. 9 The light scattering layer 110 shown in (a) of FIG. 1 is a light scattering layer 110, and the thickness of the light scattering layer 110 increases as it moves away from the incident surface 121. At this time, the concentration of the light scattering particles 112 in the light scattering layer 110 can be substantially uniform. In this way, by changing the thickness corresponding to the distance from the incident end while maintaining the uniform concentration of the particles in the light scattering layer 110, the particle concentration in the light diffuser 100 can have an in-plane distribution. In addition, in this embodiment, the concentration of the light scattering particles 112 in the light scattering layer 110 can also be distributed as in Embodiment 1.

[0152] In addition, for example, the light diffuser 100 may also have Fig.10 The light scattering layer 110 shown in (a) has a step-like layer structure. Fig.10 (a) is a cross-sectional view showing another example of the light diffuser 100 according to Embodiment 2. Fig.10 (b) is given by Fig.10 An enlarged view of a main part of the area surrounded by the dotted line in (a).

[0153] The light scattering layer 110 may also be a laminated structure of a plate-shaped light scattering layer (hereinafter referred to as a diffusion film 114) formed by dispersing light scattering particles 112 in a substrate 111. Here, the laminated structure of the diffusion film 114 may include two or more layers having different lengths in the light guiding direction of the light Lt. In addition, in the laminated structure of the diffusion film 114, the lengths of each layer (the lengths in the light guiding direction of the light Lt) may also be different. In other words, the light scattering layer 110 may also be formed by laminating diffusion films, for example, by changing the lengths of the diffusion films. More specifically, the light scattering layer 110 may also be formed by laminating a plurality of diffusion films 114 having different lengths in the light guiding direction of the light Lt in the thickness direction (Y-axis direction in the figure) of the light diffuser 100. In this way, by changing the number of layers of the laminated films constituting the light scattering layer 110 in accordance with the distance from the incident end while maintaining a uniform particle concentration in the light scattering layer 110, the particle concentration in the light diffuser 100 can be made to have an in-plane distribution. In addition, the concentration of the light scattering particles 112 in each layer of the diffusion film 114 can be the same or different in each layer. By adjusting the particle concentration of each layer, the length and configuration of each layer, and the number of layers, the particle concentration distribution in the light diffuser 100 can be easily controlled in accordance with the distance x from the incident end.

[0154] The diffusion film 114 of each layer may be bonded to the diffusion film 114 of another layer by, for example, an adhesive or thermal fusion bonding, etc. In this case, a bonding surface 131 may exist between the layers, but the method for forming the bonding surface 131 is not particularly limited.

[0155] In addition, Fig.10 In the example shown, the diffusion film 114 is stacked in a gradually shortened length in the +Y axis direction, but the diffusion film 114 may be stacked in a gradually shortened length in the -Y axis direction, or a combination of the two may be used. In this way, the stacking method of the diffusion film 114 is not particularly limited as long as the overall thickness of the diffusion film 114 is different within the plane of the main surface of the light diffuser 100.

[0156] In addition, the light diffuser 100 of the present embodiment further includes a light-transmitting layer 113. The light-transmitting layer 113 forms a part of a light-guiding portion that functions as a light-guiding path for the light Lt by bonding with the light-scattering layer 110. In other words, a structure (light-guiding portion) that functions as a light-guiding path for the light Lt is formed by the light-scattering layer 110 and the light-transmitting layer 113. In addition, the light-transmitting layer 113 is configured, for example, for the purpose of making the thickness of the light diffuser 100 uniform or flattening the main surface. For example, the light-transmitting layer 113 is configured to fill the gap generated when the stepped light-scattering layer 110 is configured relative to the target shape of the light diffuser 100. As a material for the light-transmitting layer 113, it is preferably the same material as the substrate 111, or a material having a refractive index in the wavelength band of the light Lt after molding that is substantially the same as that of the substrate 111.

[0157] In this embodiment, the light scattering layer 110 and the light transmission layer 113 are joined to form a structure (light guide portion) that functions as a light guide path for the light Lt. Therefore, the light Lt travels in the +Z axis direction while repeatedly being reflected at the surface in the light guide portion formed by the light scattering layer 110 and the light transmission layer 113. At this time, the concentration distribution of the light scattering particles 112 in the formed structure (light guide portion) increases in a nonlinear manner corresponding to the distance from the incident end in the light guiding direction of the light Lt.

[0158] In addition, in the present embodiment, the light diffuser 100 may include a transparent substrate. For example, the light scattering layer 110 and the light transmitting layer 113 may be sandwiched between two transparent substrates.

[0159] Next, a method for manufacturing the light diffuser 100 according to the present embodiment will be described. Fig.11 : is an explanatory diagram showing an example of a method for manufacturing the light diffuser 100 of the present embodiment. Fig.11 The example shown is similar to Fig. 9 Corresponding to the structural example.

[0160] In this example, a resin material (resin particles, etc.) in which light scattering particles 112 are dispersed in the same material as the base material 111 of the light scattering layer 110 is prepared (particle dispersion step). This step can be applied by a known method. Figure 7 The method shown in (a).

[0161] Next, an irregularly shaped resin molded body ( Fig.11(a): Scattering layer forming process). This process can be applied to a well-known method called irregular shape extrusion molding method. For example, using a uniaxial kneading extruder, a thermoplastic resin as a material of the substrate 111 and a particle-containing material (resin particles) prepared in the particle dispersion process are melt-mixed in a predetermined ratio while extrusion molding is performed, thereby preparing a resin molded body of a desired shape in which light scattering particles 112 are dispersed in the substrate 111 at a target concentration. For example, when the molten resin is pulled out from the extruder, the molten resin is pulled through a mold processed to give a target shape cross section, thereby preparing an irregular shape (for example, a column with a wedge-shaped cross section, etc.) light scattering layer 110 in which light scattering particles 112 are dispersed in the substrate 111 at a target addition concentration.

[0162] In addition, the particle dispersion process is not necessarily required. For example, the particle dispersion process may be performed simultaneously with the scattering layer forming process. In this case, the light scattering particles 112 may be supplied to the extruder instead of the resin material in which the light scattering particles are dispersed. For example, a single-axis kneading extruder may be used to melt-mix the light scattering particles 112 with a thermoplastic resin as a material of the substrate 111 at a predetermined ratio while performing extrusion molding using a mold, thereby preparing a resin molded body of a desired shape in which the light scattering particles 112 are dispersed in the substrate 111 at a target concentration.

[0163] At least one surface of the irregularly shaped light scattering layer 110 may also have any curved surface shape or step difference. For example, the light scattering layer 110 may also be formed into an irregular shape having a curved surface shape or step difference such that the particle concentration in the light diffuser 100 having the light scattering layer 110 (more specifically, in the structure (light guide portion) formed by the integration process described later) satisfies the above-mentioned first to third conditions, or satisfies the above-mentioned formula (1). In addition, in the scattering layer forming process, due to the influence of the friction between the extruded molten resin and the mold, striped concave and convex are sometimes observed on the surface of the light scattering layer 110 after molding. Although it can be retained, it is preferably cut and removed by grinding or the like.

[0164] In addition, as another example of a method for forming an irregularly shaped light scattering layer 110, a plurality of light scattering layers 1101 (resin molded bodies) in which light scattering particles 112 having a target concentration are dispersed in a substrate 111 can be integrated by bonding. As a method for integrating a plurality of light scattering layers 1101, the same method as in Embodiment 1 can be used.

[0165] Next, a light transmission layer 113 ( Fig.11(b): Transmission layer forming step). This step can be applied to a well-known method called irregular shape extrusion molding. For example, a thermoplastic resin as a material of the light transmission layer 113 is melted using a single-axis kneading extruder, and when the molten resin is extruded, it is pulled through a mold processed into a cross-section that can give a target shape, thereby preparing the light transmission layer 113 as a resin molded body of the desired shape.

[0166] Next, the irregularly shaped light scattering layer 110 and the light transmission layer 113 are bonded to form an integral structure of the light scattering layer 110 and the light transmission layer 113 ( Fig.11 (d): Integration step). This step can be applied by a known method. For example, the light scattering layer 110 and the light transmitting layer 113 may be bonded and integrated by an adhesive or heat welding.

[0167] In addition, the transmission layer forming step and the integration step can also be performed simultaneously. In this case, the transmission layer forming step can also be omitted. In the integration step, the irregularly shaped light scattering layer 110 prepared is compounded with the material of the light transmission layer 113, and the structure formed by integrating the light scattering layer 110 and the light transmission layer 113 is molded at the same time. In this step, for example, an injection molding method can also be used. That is, the irregularly shaped light scattering layer 110 prepared in the scattering layer forming step can also be embedded in the mold, and the thermoplastic resin as the material of the light transmission layer 113 can be filled and integrated. In addition, if the laminated film is a long strip and can be produced continuously, an extrusion molding method can also be used. That is, the integration can also be performed while compounding the thermoplastic resin as the material of the light transmission layer 113 on the irregularly shaped light scattering layer 110. As a method for integrating the light scattering layer 110 and the light transmission layer 113, the above-mentioned method is preferred, but methods other than these methods can also be used. In the integration process, as long as the light scattering layer 110 and the light transmitting layer 113 are bonded in the structure after molding, and the bonded light scattering layer 110 and the light transmitting layer 113 form a structure that functions as a light guide path for the light Lt (also referred to as a light guiding portion), regardless of the specific method used, it is referred to as bonding the light scattering layer 110 and the light transmitting layer 113. That is, the "bonding" in this process includes not only a method of simply bonding two structures, but also includes filling in the insert molding and compounding in the extrusion molding as described above.

[0168] also, Fig.12 : is an explanatory diagram showing another example of the method for manufacturing the light diffuser 100 of the present embodiment. Fig.12 The example shown is similar to Fig.10 Corresponding to the structural example.

[0169] In this example, a diffusion membrane 114 ( Fig.12 (a): Scattering layer forming step). This step can be applied by a known method. As an example, it can also be used Figure 8 In this case, the prepared diffusion film 114 can also be prepared as a single-layer light scattering layer 110 having a substantially uniform concentration. The thickness of the film is generally less than 1 mm, but if it is within the range of 10 to 150 μm, the distribution of the particle concentration can be more finely controlled, so it is more preferred. In addition, the resin molded body prepared in the above-mentioned scattering layer forming step is also called a prefabricated light scattering portion.

[0170] Next, the prepared diffusion membrane 114 is stacked in multiple layers ( Fig.12 (b): Scattering layer stacking step). For example, a plurality of diffusion films 114 may be stacked in a stepwise manner (joined in the thickness direction) with different lengths so that the number of layers increases as the distance from the incident end increases. Thus, an irregular light scattering layer 110 (stacked film structure) having different in-plane thicknesses is formed (see Fig.12 (c)). At this time, the diffusion film can also be stacked so that the particle concentration in the light diffuser 100 having the formed laminated film structure (more specifically, in the structure (light guide part) formed by the integration process described later) satisfies the above-mentioned first to third conditions, or satisfies the above-mentioned formula (1). There is no particular limitation on the method of joining the layers in the laminated structure. For example, the diffusion film 114 of each layer can be joined to the diffusion film 114 of other layers by adhesive or thermal welding. Thus, an irregular light scattering layer 110 (laminated film structure) with different in-plane thickness is formed (refer to Fig.12 (c)). As the adhesive, a solvent-type adhesive may be used in the same manner as in other embodiments.

[0171] Next, the irregularly shaped light scattering layer 110 (laminated film structure) is bonded to the light transmission layer 113, and the light scattering layer 110 and the light transmission layer 113 are integrated ( Fig.12(d): Integration process). This process can be applied by a known method. For example, an injection molding method can also be used. That is, the laminated film structure prepared in the scattering layer forming process can also be embedded in the mold, and the thermoplastic resin as the material of the light-transmitting layer 113 can be filled and integrated. In addition, if the laminated film structure is a long strip and can be produced continuously, an extrusion molding method can also be used. That is, the integration can also be performed while compounding the thermoplastic resin as the material of the light-transmitting layer 113 on the laminated film structure. As a method for integrating the laminated film structure with the light-transmitting layer 113, the above-mentioned method is preferred, but methods other than these methods can also be used. In addition, in this process, as long as the light scattering layer 110 and the light-transmitting layer 113 are bonded in the molded structure, and the bonded light scattering layer 110 and the light-transmitting layer 113 form a structure that functions as a light guide path for the light Lt (also called a light guide portion), then regardless of the specific method used, it is referred to as bonding the light scattering layer 110 and the light-transmitting layer 113. That is, the "joining" in this step includes not only a method of simply joining two structures but also includes filling in insert molding and compounding in extrusion molding as described above.

[0172] According to the above, the light diffuser 100 can be formed, which is a structure (light guide portion) that functions as a light guide path for the light Lt, including the irregularly shaped light scattering layer 110 and the light transmitting layer 113. In this example, when the light diffuser 100 has a functional layer in addition to the light guiding portion, for example, Fig.12 The structure formed by the integration step (d) is laminated with other functional layers.

[0173] In addition, depending on the molding method, in the integrated structure (light guide portion), there may be no clear boundary such as the bonding surface 131 between the light-transmitting layer 113 and the light-scattering layer 110. Even in this case, by causing light to be incident on the light diffuser 100 having the molded structure from multiple directions such as the light-guiding direction of the light Lt and the direction perpendicular to the light-guiding direction, and measuring the change in the light intensity of the scattered light thus generated, it is possible to estimate to some extent the boundary between the light-scattering layer 110 and the light-transmitting layer 113 and the particle concentration distribution in the light diffuser 100.

[0174] As described above, according to this embodiment, as in embodiment 1, the brightness or hue of the exit surface of the light diffuser can be easily controlled, and the particle concentration distribution that realizes the brightness or hue of such an exit surface can be easily implemented, so that a light diffuser with controlled brightness or hue of the exit surface and a device using the light diffuser can be simply manufactured.

[0175] in addition, Fig.13(a) to (c) are graphs showing examples of changes in the concentration (n(x)) of light scattering particles in the diffuser 100, changes in the forward light intensity (I(x)), and changes in the scattered light intensity (S(x)) relative to the distance x when light scattering particles 112 are dispersed in the light scattering layer 110 so that the particle concentration distribution in the diffuser 100 when viewed from the emission surface side satisfies the formula (1). According to the above model, Fig.13 As shown in (a), for example, when the particle concentration in the diffuser 100 relative to the distance x satisfies the formula (1), as Fig.13 As shown in (c), the intensity of scattered light relative to the distance x can be made constant.

[0176] also, Fig.14 (a) to (c) are graphs showing examples of changes in the concentration of light scattering particles (n(x)), the intensity of the forward light (I(x)), and the intensity of the scattered light (S(x)) in the diffuser 100 relative to the distance x when the particle concentration in the diffuser 100 when viewed from the emission surface side is kept constant. According to the above model, it can be seen that Fig.14 As shown in (a), for example, when the particle concentration in the diffuser 100 is constant relative to the distance x, as shown in Fig.14 As shown in (c), the intensity of the scattered light attenuates corresponding to the distance x.

[0177] In addition, in the above description, an example of using the light diffuser 100 in a lighting fixture 200 is shown, but the light diffuser 100 can also be applied to other than lighting fixtures. For example, the light diffuser 100 can also be applied to a display panel or backlight of a display device, a partition or a window, and other building materials. In addition, the application field of the light diffuser 100 is not limited to this.

[0178] Description of symbols

[0179] 200: Lighting appliances;

[0180] 10: Light source;

[0181] 11: Substrate;

[0182] 12: Light-emitting element;

[0183] 13: Luminous surface;

[0184] 100: light diffuser;

[0185] 110, 1101, 1101a, 1101b, 1101c, 1101d: light scattering layer;

[0186] 111: substrate (medium);

[0187] 112: light scattering particles;

[0188] 113: light transmission layer;

[0189] 114: diffusion membrane;

[0190] 121: incident surface;

[0191] 122, 122a, 122b: exit surface;

[0192] 123: back;

[0193] 131: joint surface;

[0194] 101a, 101b: main surfaces;

[0195] 102a, 102b, 102c, 102d: side surface;

[0196] 41: Materials;

[0197] 42: containing particle material (resin particles);

[0198] 43: Adhesive;

[0199] 51A: resin material supply device;

[0200] 51B: Gravimetric powder and granule supply device;

[0201] 52A, 52B: hopper;

[0202] 53: extruder (single-shaft mixing extruder);

[0203] 54: T-type mold;

[0204] 55: traction roller;

[0205] 56a, 56b: cutting machine.

Claims

1. A light diffuser that allows first light to enter and emits scattered light, characterized in that: The light diffuser has: An incident surface for the first light to be incident on; a first light scattering unit including light scattering particles present in a medium, and generating the scattered light by guiding the incident first light and scattering the light by the light scattering particles; and an exit surface for emitting the scattered light, The concentration distribution of the light scattering particles in the light diffuser increases continuously or discontinuously in a nonlinear manner in accordance with the distance from the incident end in the light guiding direction of the first light. The light diffuser further includes a light-transmitting portion, wherein the light-transmitting portion does not contain the light-scattering particles in a medium. The first light scattering portion and the light transmitting portion joined to the first light scattering portion form a light guiding portion, and the light guiding portion functions as a light guiding path for the first light. The first light scattering portion is a stacked structure of two or more diffusion films, the diffusion films are plate-shaped and have the light scattering particles dispersed therein, and the plate-shaped portions of the two or more diffusion films have different lengths in a light guiding direction of the first light.

2. The light diffuser according to claim 1, wherein: When the distance from the incident end in the light guiding direction of the first light is x and the concentration distribution represented by the concentration relative to the distance x is n(x), the concentration distribution n(x) satisfies a prescribed fractional function, and the prescribed fractional function is represented by the ratio S0 / I0 of the scattered light intensity S0 at the incident end of the first light to the incident light intensity I0, the cross-sectional area q of the light scattering particles, and the scattering probability p of the light scattering particles.

3. The light diffuser according to claim 1, wherein: The light diffuser is a light diffuser into which the first light is incident and from which the scattered light simulating the blue sky is emitted. The light scattering particles are nanoparticles, The first light scattering unit generates the scattered light by utilizing Rayleigh scattering of the light scattering particles.

4. The light diffuser according to claim 2, wherein: The light diffuser is a light diffuser into which the first light is incident and from which the scattered light simulating the blue sky is emitted. The light scattering particles are nanoparticles, The first light scattering unit generates the scattered light by utilizing Rayleigh scattering of the light scattering particles.

5. The light diffuser according to any one of claims 1 to 4, wherein: The light diffuser is a light diffuser into which the first light is incident and from which the scattered light simulating the blue sky is emitted. The light scattering particles are nanoparticles, The scattered light has a correlated color temperature higher than a correlated color temperature of the first light.

6. The light diffuser according to any one of claims 1 to 4, wherein: The first light scattering portion includes a plurality of second light scattering portions, which are arranged along the light guiding direction of the first light and respectively include light scattering particles existing in a medium, and the concentrations of the light scattering particles in the medium are different.

7. The light diffuser according to claim 5, wherein: The first light scattering portion includes a plurality of second light scattering portions, which are arranged along the light guiding direction of the first light and respectively include light scattering particles existing in a medium, and the concentrations of the light scattering particles in the medium are different.

8. The light diffuser according to claim 1, wherein: In the stacked structure, the diffusion films are stacked in a direction perpendicular to the light guiding direction of the first light to form a stepped layer structure.

9. The light diffuser according to claim 1 or 8, wherein: In the diffusion film constituting each layer of the stacked structure, the concentration of the light scattering particles in the diffusion film is substantially constant.

10. The light diffuser according to claim 1 or 8, wherein: The first light repeatedly reflects on a surface of the light guide portion in the light guide portion, and travels toward an end surface opposite to the incident surface. The light guide portion is formed of the light transmitting portion and the stacked structure as the first light scattering portion.

11. The light diffuser according to claim 9, wherein: The first light repeatedly reflects on a surface of the light guide portion in the light guide portion, and travels toward an end surface opposite to the incident surface. The light guide portion is formed of the light transmitting portion and the stacked structure as the first light scattering portion.

12. The light diffuser according to claim 1, wherein: The first light scattering portion is a structure in which the concentration of the light scattering particles in a medium is substantially constant and has a predetermined curved surface shape or a step difference.

13. The light diffuser according to any one of claims 1 to 4, wherein: The light diffuser includes a plurality of incident surfaces on which the first light is incident. The concentration distribution increases continuously or discontinuously in a nonlinear manner in accordance with the distance from all incident ends in all light guiding directions of the first light.

14. The light diffuser according to any one of claims 1 to 4, wherein: The light diffuser is in a plate shape or a rod shape.

15. A lighting fixture, characterized in that: The lighting device comprises: a light source that emits the first light; and The light diffuser according to any one of claims 1 to 14.

16. A method for manufacturing a light diffuser, the light diffuser comprising: an incident surface for first light to be incident; a light scattering portion comprising light scattering particles present in a medium, the light scattering portion generating scattered light by guiding the incident first light and scattering the light by the light scattering particles; and an exit surface for emitting the scattered light, the method for manufacturing the light diffuser comprising: The first step is to disperse the light scattering particles in the material of the medium to form a plurality of prefabricated light scattering parts of a predetermined shape, wherein the plurality of prefabricated light scattering parts respectively contain light scattering particles in the medium, and at least one of the concentration of the light scattering particles in the medium and the length in the light guiding direction of the first light is different; and In a second step, the plurality of prefabricated light scattering portions formed in the first step are joined to form the light scattering portion. in, The plurality of prefabricated light scattering parts are in the shape of plates and have different lengths. In each of the prefabricated light scattering sections, the concentration of the light scattering particles in the medium is substantially constant, In the second step, the light scattering portion is formed to have a stacked structure by bonding the plurality of prefabricated light scattering portions in a thickness direction. The method for manufacturing the light diffuser further includes a third step of bonding the light scattering portion formed in the second step to a light transmitting portion in a medium that does not contain the light scattering particles to form a structure of a predetermined shape, wherein the structure of the predetermined shape functions as a light guide path for the first light.

17. The method for manufacturing a light diffuser according to claim 16, wherein: In the second step, the plurality of prefabricated light scattering sections are arranged and joined so that the concentration of the light scattering particles in the formed light scattering sections increases continuously or discontinuously in a nonlinear manner corresponding to the distance from the incident end in the light guiding direction of the first light.

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