JP2013140704A - Reflected light diffusion layer and light guide device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide device that can exert at least either effect of (1) high luminance and (2) little unevenness of luminance, and a reflected light diffusion layer used for the same.SOLUTION: The reflected light diffusion layer 12b is arranged between a light guide plate 11 and a reflection layer 12a. The reflected light diffusion layer 12b incudes a light-transmitting matrix and nano hollow silica particles. The nano hollow silica particles have a primary particle size of 500 nm or less, a wall thickness of 30 nm or less, and a porosity of 40% or more. The nano hollow silica particles are coagulated in the matrix and their secondary aggregated particle diameter is 1,500 nm or less. Further, a thickness of the reflected light diffusion layer 12b is 3 μm or more and 10 μm or less.

Description

  The present invention relates to a reflected light diffusion layer disposed between a light guide plate and a reflective layer, and a light guide device using the same.

  A light guide device is used in many industrial fields such as a light-emitting device using a liquid crystal television or an LED (for example, Patent Document 1). These light guide devices are required to have high luminance and uniform light emission on the light emitting surface, and each member constituting the light guide device performs the functions required for this, and improves the light intensity. It is necessary to reduce the attenuation.

Japanese Patent Laid-Open No. 2004-6187

  However, the conventional light guide device has a problem that sufficient luminance is not yet obtained and luminance unevenness is large. The present invention has been made in view of the above-described conventional situation, and a light guide device capable of producing at least one of the effects of (1) high luminance and (2) low luminance unevenness, and the same Providing a reflected light diffusion layer to be used is a problem to be solved.

A first aspect of the present invention is a reflected light diffusing layer disposed between a light guide plate and a reflective layer, a light-transmitting matrix, and nano hollow silica particles dispersed in the matrix, The nano hollow silica particles have a primary particle diameter of 500 nm or less, a wall thickness of 30 nm or less, a porosity of 40% or more, and are aggregated in the matrix, and the secondary aggregate particle diameter is 1500 nm. It is the reflected light diffusion layer containing the nano hollow silica particle which is the following.
It should be understood by those skilled in the art that the “light guide plate” in the present specification is not limited to a plate-like object.

The reflected light diffusion layer of the present invention is disposed between the light guide plate and the reflective layer,
(1) The reflected light diffusing function that the light reflected by the reflecting layer is diffused by the nano hollow silica particles in the reflected light diffusing layer, and the light emission on the light emitting surface is made uniform;
(2) The light leaking to the surface opposite to the light emitting surface of the light guide plate is reflected and / or refracted by the nano hollow silica particles in the reflected light diffusing layer, and returned to the light emitting surface side. It exhibits a light reflection function that increases brightness.
The reason will be described below.

  The nano hollow silica particles contained in the reflected light diffusion layer of the present invention are dispersed in a light-transmitting matrix, the primary particle diameter is extremely small as 500 nm or less, and the wall thickness is extremely thin as 30 nm or less. Has been. For this reason, the particle diameter and wall thickness of the nano hollow silica particles are less than or equal to the wavelength of visible light or infrared light, and transparency to visible light or infrared light is not easily lost. In addition, the nano hollow silica particles have a high light transmittance in combination with the porosity of 40% or higher. For this reason, there is little attenuation of the light intensity in the reflected light diffusion layer.

  Further, the scattering of the nano hollow silica particles occurs not only on the outer surface of the particle but also on the inner surface of the particle (see FIG. 5). Furthermore, since it has a hollow structure, unlike solid particles, energy attenuation of light entering the inside of the particles is small, and scattering occurs efficiently (see FIGS. 5 and 6). For this reason, the reflected light diffusion layer of the present invention has a scattering effect while ensuring transparency. In other words, the balance between permeability (some of which passes through the inside of the particle) and scattering (some of the inner wall of the particle) are different from solid particles, so that it has a characteristic of uniformly scattering while ensuring transparency. It becomes. Such a characteristic occurs efficiently and uniformly in combination with the high permeability and high scattering property of the nano hollow silica particles below the agglomerates of a size that does not become opaque under visible light.

  According to the test results of the present inventors, the nano hollow silica particles in the reflected light diffusing layer of the present invention become large secondary agglomerated particles in the reflected light diffusing layer, and therefore, as secondary agglomerated particles enclosing air. It is considered that both high transmittance and high scattering are compatible with each other. Further, taking advantage of such characteristics, the balance between transmission and scattering can be adjusted by the secondary aggregated particles. That is, regarding the scattering, since the scattering from one particle (there is also the inner wall part of the particle) and the scattering of the outer wall of the secondary aggregated particle overlap, this component is adjusted. Specifically, the balance between transmission and scattering can be adjusted by adjusting the primary particle diameter, silica cell wall thickness, porosity and secondary aggregate particle diameter in the nano hollow silica particles.

  Therefore, when the reflected light diffusing layer of the present invention is used in a light guide device, a light guide device that can solve at least one of high luminance and low luminance unevenness can be obtained. The secondary agglomerated particle diameter of the nano hollow silica particles is 1500 nm or less, preferably 500 nm to 1500 nm, and more preferably 700 nm to 1000 nm. When the secondary aggregate particle diameter is less than 500 nm, light scattering and reflection are difficult to occur. On the other hand, if the secondary agglomerated particle diameter exceeds 1500 nm, the light transmittance is deteriorated, and the luminance on the light emitting surface of the light guide plate is lowered.

In the reflected light diffusing layer of the second aspect of the present invention, the reflective layer reflects light regularly and adheres to the reflective layer.
Since the reflected light diffusing layer of the present invention contains nano hollow silica particles and has excellent light transmittance, the ratio of light leaking to the surface opposite to the light emitting surface of the light guide plate increases. There is a fear. For this reason, if the reflective layer is a reflective layer made of a specular reflective material such as an aluminum plate, leakage to the surface opposite to the light emitting surface of the light guide plate can be made extremely small. The effect of improving the brightness is high.
In addition, if the reflected light diffusing layer is in close contact with the reflecting layer, it is not necessary to consider the influence of a slight gap generated between the reflected light diffusing layer and the reflecting layer, so that the optical characteristics can be easily predicted. Thus, the calculation becomes easy.

In the reflected light diffusion layer of the third aspect of the present invention, the layer thickness is 3 to 10 μm. According to the test results of the present inventors, when the thickness of the reflected light diffusion layer exceeds 10 μm, the light transmittance is lowered, and the effect of improving the luminance is reduced. On the other hand, if the thickness is less than 3 μm, the light diffusion function is weakened and the luminance unevenness is increased.
The light guide device according to the fourth aspect of the present invention has a reflected light diffusion layer, has high luminance, and has little luminance unevenness.

It is a disassembled perspective view of the sidelight type light guide device of an embodiment. It is a schematic cross section of the side light type light guide device of an embodiment. It is a top view of the sidelight type light guide device of an example and a comparative example (the number enclosed with ◯ shows the position where the luminance was measured). It is a schematic cross section of the light guide device according to the example. It is a schematic diagram which shows scattering and permeation | transmission of the light by a nano hollow silica particle. It is a schematic diagram which shows scattering and permeation | transmission of the light by a solid particle.

FIG. 1 is an exploded perspective view of an embodiment in which a reflected light diffusion layer of the present invention is applied to a sidelight type light guide device. This side light type light guide device includes a light guide device body 10 and an LED light source 20 installed on a side surface of the light guide device body 10 (a light source such as a fluorescent tube may be disposed instead of the LED light source 20). ).
The light guide device main body 10 includes a light guide plate 11, and the light guide plate 11 is opposite to the light guide plate main body 11a made of a colorless and transparent acrylic resin and the light emission surface of the light guide plate main body 11a, as shown in FIG. The light distribution layer 11b is dot-printed on the side surface (hereinafter referred to as “back side surface”). The light distribution layer 11b may or may not contain nano hollow silica particles. Light scattering fine particles such as silica fume can be added to the light distribution layer 11b. The light distribution layer 11b can be formed by printing a light transmissive resin solution composition described later by screen printing or the like. A reflective layer 12 made of an aluminum plate is laminated on the back side surface of the light guide plate 11. Here, the term “lamination” includes not only the case where the layers are in close contact with each other, but also the case where the layers are simply stacked and not bonded (that is, a case where there is a slight gap between layers). In FIG. 2, the light distribution layer 11b is dot-printed. However, the present invention is not limited to this, and a suitable printing pattern can be adopted depending on the purpose, and it can be formed by a method other than printing such as coating or spin coating. Alternatively, the light guide plate body 11a may be a separate sheet.
A reflective member 12 is laminated on the back side surface of the light guide plate 11. The reflection member 12 has a structure in which a reflection light diffusion layer 12b having a thickness of 3 to 10 μm is laminated on a reflection layer 12a. The reflected light diffusing layer 12b can be formed by printing a light transmissive resin solution composition described later on the reflective layer 12a by screen printing or the like.

On the other hand, a first emission light diffusion layer 13 is laminated on the light emission surface side of the light guide plate 11. The first emitted light diffusion layer 13 has a structure in which a light scattering particle-containing layer 13b for diffusing emitted light from the light guide plate 11 is laminated on the back side surface of a film 13a made of a colorless transparent resin such as acrylic. Yes. The thickness of the light-scattering particle-containing layer 13b is adjusted as appropriate so that the diffusion effect required for making the brightness of the emitted light uniform and the required light transmittance can be achieved. The light scattering particle-containing layer 13b can be formed by printing a light-transmitting resin solution composition described later on the film 13a by screen printing or the like. Further, the light scattering particle-containing layer 13b may be incorporated in the film 13a, may be dispersed, or may be integrally formed.
The first emitted light diffusing layer 13 may be formed on the light guide plate body 11a by printing or other deposition methods without using a separate sheet from the light guide plate body 11a.

  Further, on the light emission surface side of the first emission light diffusion layer 13, the light collection layer 14 fulfills the function of concentrating the emission light from the first emission light diffusion layer 13 by the refraction action to improve the front luminance. Is provided. The condensing layer 14 is made of a colorless and transparent resin, and has a structure in which structural rows having a triangular cross section are arranged. In FIGS. 1 and 2, only one condensing layer 14 is provided, but it is also preferable to insert a plurality of condensing layers so that triangular structure rows are orthogonal to each other. A condensing layer having a microlens structure can also be employed.

A second emission light diffusion layer 15 for making the brightness of the emitted light from the condensing layer 14 uniform is laminated on the light emitting surface side of the condensing layer 14. The second emission light diffusion layer 15 has a structure in which a light scattering particle-containing layer 15b for diffusing emission light is laminated on the light emission surface side of a film 15a made of a colorless and transparent resin such as acrylic.
Nano hollow silica particles may or may not be included as the light diffusing particles used in the first and second emission light diffusing layers. Moreover, general-purpose light diffusing particles can be employed according to the purpose and application.

(Light transmissive resin solution composition)
The light-transmitting resin solution composition described above is a viscous liquid in which nano hollow silica particles are dispersed in a light-transmitting matrix dissolved in a solvent. In addition, when the light diffusibility is insufficient only with the nano hollow silica particles, a medium for light diffusion may be added. In this case, the light diffusion medium is preferably transparent. This is because the attenuation of light in the reflected light diffusion layer 12b is reduced. Moreover, you may add the thickener etc. for providing the viscosity suitable for printing, and thixotropy.

What is necessary is just to determine suitably the addition amount in the case of adding a light-diffusion particle other than a nano hollow silica particle considering the balance of scattering and permeation | transmission of the light irradiated in the light-guide plate. If the amount and ratio of the nano hollow silica particles are increased, both the scattered light and the transmitted light are increased, so that the surface on which the light diffusion layer is provided becomes brighter. On the other hand, when the light diffusing particles are solid particles having a low light transmittance, the scattered light increases, but the transmitted light decreases, so the surface opposite to the side where the light diffusing layer is provided becomes bright. Furthermore, the balance between transmission and scattering can also be adjusted by adjusting the components of the light diffusing particles other than the nano hollow silica particles and the diameter of the primary particles.
The following ranges are usually recommended.
Nano hollow silica particles:
10 wt% to 40 wt%, preferably 15 wt% to 30 wt%, more preferably 20 wt% to 25 wt%.
Light diffusion particles other than nano hollow silica particles:
20 wt% to 80 wt%, preferably 30 wt% to 60 wt%, more preferably 40 wt% to 50 wt%.

  It is good also as a nano hollow silica particle, without adding a light-diffusion particle. Even when the particle diameter of the nano hollow silica particles is smaller than the wavelength of light, they aggregate in the reflected light diffusion layer to form large secondary particles. This is because both scattering can be achieved.

The light-transmitting matrix is not particularly limited as long as it is a material that transmits light. For example, transparent resin or inorganic glass is used. Examples of the transparent resin include polycarbonate resin, ABS (acrylonitrile-butadiene-styrene copolymer) resin, methacrylic resin, methyl methacrylate-styrene copolymer resin, polystyrene resin, acrylonitrile-styrene copolymer (AS) resin, polyethylene. Examples thereof include polyolefin resins such as resins and polypropylene resins, acrylic resins, epoxy resins, silicone resins, and polyimide resins.
In this specification, light includes infrared light and ultraviolet light as well as visible light.

  Nano hollow silica particles dispersed in the light transmissive resin solution composition have a primary particle diameter of 500 nm or less, a wall thickness of 30 nm or less, and a porosity of 40% or more. Preferably, the primary particle size is 10 nm to 450 nm, the wall thickness is 5 nm to 30 nm, and the porosity is 40% to 90%.

Such hollow nanoparticles can be produced, for example, by the method described in JP-A-2005-263550. That is, in the method for producing hollow particles composed of silica shells by the first step of preparing calcium carbonate, the second step of coating calcium carbonate with silica, and the third step of dissolving calcium carbonate,
(1) In the first step, calcium carbonate having a primary particle size of 20 to 200 nm by transmission electron microscopy was prepared in an aqueous system and aged so that the particle size by static light diffusion method was 20 to 700 nm. After that, dehydrated to form a water-containing cake,
(2) In the second step, the water-containing cake of (1) is dispersed in alcohol, and ammonia water, water, and silicon alkoxide are contained in the ammonia water in a volume ratio of silicon alkoxide / alcohol of 0.002 to 0.1. NH ₃ is added in an amount of 4 to 15 mol with respect to 1 mol of silicon alkoxide, and water is added in an amount of 25 to 200 mol with respect to 1 mol of silicon alkoxide. After preparation, washing with alcohol and water, again as a water-containing cake,
(3) In the third step, by dispersing the water-containing cake of (2) in water, adding an acid, and dissolving the calcium carbonate by adjusting the acid concentration of the liquid to 0.1 to 3 mol / L These are highly dispersed hollow particles composed of a dense silica shell.

  According to this method, the primary particle size by transmission electron microscopy is 30 to 500 nm, the particle size by static light diffusion method is 30 to 800 nm, the wall thickness is 5 to 30 nm, and the pore distribution is measured by mercury porosimetry. Highly dispersed silica nano hollow particles in which pores of 2 to 20 nm are not detected can be produced. Further, the calcium carbonate crystals prepared in the first step are calcite and hexagonal, but by controlling the synthesis conditions, the shape as if it were cubic, that is, “cubic” Can grow. Here, “cubic” means not only a cube but also a shape similar to a cube surrounded by a surface.

  The inventors, following this method, adjust the drug concentration, the stirring method, the temperature, the type of alkali, etc. as appropriate, so that the nano hollow silica has various primary particle diameters, wall thicknesses, and porosity shown below. It has been confirmed that the particles can be produced.

  Further, the nano hollow silica particles may be subjected to a hydrophobic treatment with a surface treatment agent in order to facilitate dispersion in the transparent matrix.

Next, operations and effects of the side light type light guide device of the embodiment will be described.
In this side light type light guide device, the light irradiated from the side surface of the light guide 11 by the LED light source 20 travels while reflecting in the light guide plate body 11a at the boundary surface, and the light scattering in the light distribution layer 11b. Scattered by the particles, part of which proceeds to the back side. The light that has escaped to the back surface side thus enters the reflected light diffusion layer 12 b of the reflecting member 12. Here, since the reflected light diffusing layer 12b contains nano hollow silica particles, (1) the reflected light that diffuses the light reflected by the reflecting layer and makes the light emission on the light emitting surface uniform. Diffusing function and (2) Light reflecting function of reflecting and / or refracting light leaking to the surface opposite to the light emitting surface of the light guide plate and returning the light emitting surface side to increase the brightness of the light emitting surface And will be demonstrated. In addition, since the primary particle diameter of the nano hollow silica particles is 500 nm or less, the wall thickness is 30 nm or less, and the porosity is 40% or more, it has high light transmittance, and light in the reflected light diffusion layer 12b. Less attenuation of strength. Moreover, scattering of the nano hollow silica particles occurs not only on the outer surface of the particle but also on the inner surface of the particle. Furthermore, since it has a hollow structure, unlike solid particles, there is little energy attenuation of light entering the inside of the particles, and efficient scattering occurs. For this reason, the reflected light diffusion layer of the present invention has a scattering effect while ensuring transparency. In other words, the balance between permeability (some of which passes through the inside of the particle) and scattering (some of the inner wall of the particle) are different from solid particles, so that it has a characteristic of uniformly scattering while ensuring transparency. It becomes. Such a feature is an agglomerate of a size that does not become opaque under visible light, and in the following, the high permeability and high scattering properties of the nano hollow silica particles occur efficiently and uniformly.
The light transmitted to the back side surface due to the high light transmittance of the reflected light diffusing layer 12b is reflected by the reflecting layer 12a, returned to the reflected light diffusing layer 12b, scattered again, and led as light with less luminance unevenness. Irradiated to the optical plate 11 side. For this reason, the loss of light dissipated on the back side is also reduced.
Therefore, the reflected light diffusing layer 12b can reflect light with high luminance and little luminance unevenness to the light guide plate 11 side.

  The light returned to the light guide plate 11 side by the reflecting member 12 composed of the reflected light diffusing layer 12b and the reflective layer 12a as described above is reflected in the light guide plate 11, and the light that has escaped to the light emitting surface side is the first light. 1 Diffused by the emitted light diffusion layer 13, the luminance unevenness is improved, and enters the light condensing layer 14. The condensing layer 14 has a function of condensing the emitted light to the front by a refracting action and improving the front luminance. Then, the light is diffused by the second emission light diffusion layer 15 to improve luminance unevenness, and light is emitted with high luminance and little luminance unevenness on the front side.

Example 1
・ Manufacture of reflective members Toray white PET film Lumirror E60V is used as the base material of the reflective layer, nano hollow silica (NanoBalloon XP200-Methyl from GRANDEX (primary particle diameter 200nm / secondary particle diameter 1000nm, wall thickness 10nm, Methyl group modification) A coating agent made of an acrylate resin (dispersed in methyl ethyl ketone as a solvent) with 20% by weight added is uniformly applied to a predetermined film thickness (7 μm in Example 1-1, 14 μm in Example 1-2). The coated member was used as the reflective member of Example 1.
・ Production of light guide plate
A light guide pattern was printed by screen printing using SR931 white medium ink made by Mino Group as a diffusion layer on an A5 / 5mm thick acrylic plate. This was made into the light-guide plate for light sources.
Assembling the light guide device As shown in FIG. 4, the LED light source 40 is placed on the side surface on the short side of the light guide plate 31, the reflecting member 12 is brought into close contact with the light guide pattern printing surface 31 b side of the light guide plate 31, Reiko Ruillite as a diffusion sheet 33 was adhered to the light emitting side surface of the light guide plate.

(Example 2)
In Example 2, an aluminum reflective sheet made of Toyo Aluminum was used as the base material of the reflective layer, and GRANDEX NanoBalloon XP200-Methyl (nano hollow silica, primary particle diameter 200 nm / secondary particle diameter 1000 m, wall thickness 10 nm, Methyl group modified product ) Resin added in an amount of 20% by weight (dispersed in methyl ethyl ketone as a solvent) is uniformly coated to a predetermined thickness (7 μm in Example 2-1 and 14 μm in Example 2-2). A reflecting member was used. Others are the same as those in the first embodiment, and a description thereof will be omitted.

(Comparative Example 1)
In Comparative Example 1, Toray white PET film Lumirror E60V was used as it was without coating as the base material of the reflective layer. Others are the same as those in the first embodiment, and a description thereof will be omitted.

(Comparative Example 2)
In Comparative Example 2, an aluminum reflective sheet made of Toyo Aluminum was used as it was without coating as the base material of the reflective layer. Others are the same as in the second embodiment, and a description thereof will be omitted.

<Evaluation>
For the light guide devices of Example 1-1, Example 1-2, Example 2-1, Example 2-2, Comparative Example 1 and Comparative Example 2, the luminance of the radiation surface when the LED light source is turned on Measured at each location. As shown in FIG. 3, the luminance measurement points were arranged in two rows and eight places at equal intervals. Konica Minolta Sensing Co., Ltd. CA-1500W was used for measuring the luminance. The results are shown in Table 2 for the case where the base material of the reflective layer is a white PET film (that is, in the case of Example 1-1, Example 1-2, and Comparative Example 1), and in the case of the aluminum reflective sheet (that is, the case of implementation). Table 2-1 shows Examples 2-1 and Examples 2-2 and Comparative Example 2.

  From Table 2 above, when the base material of the reflective layer is white PET, in Example 1-1 in which the reflected light diffusing layer containing nano hollow silica was formed to 7 μm, the reflected light diffusing layer containing nano hollow silica was It was found that the brightness was improved by about 5.6% on average compared to Comparative Example 1 that was not formed.

  Also, from Table 3 above, in Example 2-1 in which the reflective light diffusion layer containing nano hollow silica was formed with a thickness of 7 μm when the base material of the reflective layer was an aluminum reflective sheet, It was found that the luminance was improved by about 10% in average value as compared with Comparative Example 2 in which the reflected light diffusion layer was not formed. On the other hand, when the reflection light diffusion layer containing nano hollow silica was formed with a thickness of 14 μm, the improvement was about 4.6%.

The above results can be interpreted as follows. That is, when the base material of the reflection layer is white PET, the reflection layer has a structure using irregular reflection, so that even if a reflected light diffusion layer containing nano hollow silica is formed thereon, the irregular reflection point is increased. The effect of film thickness is small because of the improvement in brightness.
On the other hand, when the base material of the reflective layer is an aluminum reflective sheet, the reflective layer uses regular reflection, so that the reflective surface of the aluminum reflective sheet itself is irregularly reflected by the reflected light diffusion layer containing nano hollow silica. For the hybrid of regular reflection and irregular reflection, a certain degree of light transmittance is required for the coating layer of nano hollow silica as the irregular reflection layer. In this case, since the light transmittance decreases as the coating film thickness increases, it is considered that the 7 μm thickness has a higher luminance improvement effect than the 14 μm thickness.
In consideration of the above, it has been found that it is most preferable to apply a reflection light diffusion layer containing nano hollow silica in a thickness of 7 μm to an aluminum reflection sheet having a regular reflection structure as a reflection sheet structure.

In the above embodiment, the panel for LED has been described, but it can be applied to all uses that require light diffusion. Specifically, it is used for light guide plates (for liquid crystal TVs, advertisements, billboards, lighting, automotive meter panels, etc.), automotive instrumentation using LED transmitted light, and display panels for home appliances, and for liquid crystal TVs. Used for diffuser plates, LCD TV reflective sheets, fluorescent / halogen lamp lenses and surface coatings, LED bulbs / LED lighting, various lighting / signboard equipment, headlights / tail lamps for automobiles and bicycles, etc. Can do. For these uses, the surface of the light-transmitting material can be coated by a method such as screen printing, or can be used as a bulk material.
In the above embodiment, the LED is the light source. However, the light source is not limited to the LED, and can be applied to a fluorescent light source such as a cold cathode tube.

The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims.
In the above embodiment, an example in which nano hollow silica is blended in the reflected light diffusion layer has been described. It goes without saying that well-known and widely used members and materials can be used for elements other than the reflected light diffusion layer. In addition, nano hollow silica can be blended into at least one of the light distribution layer, the first emission light diffusion layer, and the second emission light diffusion layer as defined in the present invention.
The number of the emitted light diffusing layer and the condensing layer and the order in which they are stacked are not limited to the above. Free combinations are allowed, such as combining multiple sheets or changing the order of placing each layer from the light emitting surface.

DESCRIPTION OF SYMBOLS 11 ... Light guide plate 11a ... Light guide plate main body 11b ... Light distribution layer 12 ... Reflective member 12a ... Reflective layer 12b ... Reflected light diffusion layer

Claims (4)

A reflected light diffusion layer disposed between the light guide plate and the reflective layer,
A light transmissive matrix;
Nano hollow silica particles dispersed in the matrix, the nano hollow silica particles having a primary particle diameter of 500 nm or less, aggregated in the matrix, and a secondary aggregate particle diameter of 1500 nm or less. A reflected light diffusion layer comprising hollow silica particles.   The reflected light diffusing layer according to claim 1, wherein the reflective layer reflects light regularly and adheres closely to the reflective layer.   The reflected light diffusion layer according to claim 2, wherein the layer thickness is 3 or more and 10 μm or less.   A light guide device comprising the reflected light diffusion layer according to claim 1.