Light diffuser, liquid composition, ambient light sensor, and electronic device

Abstract

This light diffuser is provided with a light diffuser layer. The light diffuser transmits a portion of visible light and absorbs a portion of near-infrared light. The light diffuser has a haze of 20% or more.

Description

Light diffusers, liquid compositions, ambient light sensors, and electronic devices

[0001] The present invention relates to a light diffuser, a liquid composition, an ambient light sensor, and electronic equipment.

[0002] Electronic devices equipped with displays, such as smartphones and personal computers (PCs), may be equipped with ambient light sensors. For example, the brightness of the electronic device's display may be adjusted according to the output of the ambient light sensor. If such an ambient light sensor detects that the ambient light is bright, for example due to sunlight, the display brightness will be adjusted to a higher level. Conversely, if the ambient light brightness is detected to be below a certain level due to shade, for example, the display brightness will be adjusted to a lower level.

[0003] Patent Document 1 describes an electronic device equipped with a predetermined optical element, the optical element comprising an ambient light sensor. Examples of electronic devices include laptop computers and mobile phones. The optical element comprises a diffuser, which comprises a polymer layer embedded with a plurality of flakes of an inorganic dielectric material that diffuses light. Each of the plurality of flakes embedded in the polymer layer has a dielectric stack (dielectric multilayer structure; the same applies hereinafter) having alternating first layers with a first refractive index and second layers with a second refractive index. The second refractive index is lower than the first refractive index. The dielectric stack forms a thin-film interference filter and is configured to block infrared light. The diffuser has a haze of 20% or more.

[0004] U.S. Patent No. 1,175,459

[0005] The diffuser described in Patent Document 1 is understood to block light of a specific wavelength by reflection. Therefore, reflected light may reach the ambient light sensor through re-reflection, potentially affecting the output of the ambient light sensor. Furthermore, since the shielding of light of a specific wavelength is achieved by a dielectric stack, the transmission spectrum may vary depending on the angle of incidence of the light.

[0006] In view of such circumstances, the present invention provides a technology that can shield light of a specific wavelength while allowing light diffusion and can solve problems caused by reflection of light of a specific wavelength.

[0007] The present invention provides a light diffuser that includes a light diffusion layer, transmits a part of visible light, absorbs a part of near-infrared light, and has a haze of 20% or more.

[0008] The present invention also provides a liquid composition that includes light-absorbing particles and a solvent, and the liquid composition cures to form a light diffusion layer.

[0009] The present invention further provides an ambient light sensor that includes the above light diffuser and a photodetector that receives light transmitted through the light diffuser.

[0010] The present invention further provides an electronic device that includes a display, the above ambient light sensor, and a control device that adjusts the brightness of the display according to the output of the ambient light sensor.

[0011] The above light diffuser can shield light of a specific wavelength while allowing light diffusion and can solve problems caused by reflection of light of a specific wavelength.

[0012] Figure 1A is a schematic cross-sectional view showing an example of a light diffuser according to the present invention. Figure 1B is a schematic cross-sectional view showing another example of a light diffuser according to the present invention. Figure 2 is a block diagram showing an example of an electronic device according to the present invention. Figure 3 is a perspective view showing an example of an electronic device according to the present invention. Figure 4 is a perspective view showing another example of an electronic device according to the present invention. Figure 5 is a schematic cross-sectional view showing an example of an ambient light sensor. Figure 6 is a schematic cross-sectional view showing a part of an ambient light sensor. Figure 7 is a schematic cross-sectional view showing another example of an ambient light sensor. Figure 8 is a graph showing the transmission spectrum of a light diffuser according to Example 1. Figure 9 is a graph showing the transmission spectrum of a light diffuser according to Example 2. Figure 10 is a graph showing the transmission spectrum of a light diffuser according to Example 3. Figure 11 is a graph showing the transmission spectrum of a light diffuser according to Example 4. Figure 12 is a graph showing the transmission spectrum of a light diffuser according to Example 5. Figure 13 is a graph showing the transmission spectrum of a light diffuser according to Example 6. Figure 14 is a graph showing the transmission spectrum of a light diffuser according to Example 7. Figure 15 is a graph showing the transmission spectrum of a light diffuser according to Example 8. Figure 16 is a graph showing the transmission spectrum of the light diffuser according to Example 9. Figure 17 is a graph showing the transmission spectrum of the light diffuser according to Example 10. Figure 18 is a graph showing the transmission spectrum of the light diffuser according to Example 11. Figure 19 is a graph showing the transmission spectrum of the light diffuser according to Example 12. Figure 20 is a graph showing the transmission spectrum of the light diffuser according to Example 13.

[0013] The following describes embodiments of the present invention. Note that the following description is illustrative and not limited to the embodiments described below.

[0014] As shown in Figure 1A, the light diffuser 1a includes a light diffusing layer 10. The light diffuser 1a transmits a portion of visible light and absorbs a portion of near-infrared light. The lower limit of the wavelength of visible light is, for example, 360 nm to 400 nm, and the upper limit of the wavelength of visible light is, for example, 760 nm to 830 nm. The lower limit of the wavelength of near-infrared light is the long-wavelength end of visible light (760 nm to 830 nm), and the upper limit of the wavelength of near-infrared light is 2500 nm. Since the light diffuser 1a absorbs and shields a portion of the near-infrared light, problems associated with shielding the near-infrared light to be shielded by reflection are less likely to occur. For example, it is easier to avoid the operation of electronic equipment equipped with the light diffuser 1a being affected by re-reflection of reflected light. In addition, the light transmission characteristics and light shielding characteristics of the light diffuser 1a do not easily fluctuate with the angle of incidence of the incident light. The light diffuser 1a has a haze of 20% or more. Therefore, the light diffuser 1a can exhibit the desired light diffusing properties. Haze can be determined, for example, by calculating the ratio of the total light transmittance TT to the diffuse transmittance DIF (which excludes the parallel transmission component) using an integrating sphere or the like. Haze may also be measured, for example, in accordance with Japanese Industrial Standard (JIS) K 7136:2000, using equipment capable of measuring according to that standard.

[0015] The shape of the light diffuser 1a is not limited to a specific shape. For example, the light diffuser 1a may be in the form of a film. The light diffuser 1a may also be in a shape other than a film.

[0016] When the light diffuser 1a is in the form of a film, the thickness of the light diffuser 1a is not limited to a specific value. The thickness of the light diffuser 1a is, for example, 500 μm or less. This makes it easier to lower the height of the article equipped with the light diffuser 1a. The thickness of the light diffuser 1a is preferably 400 μm or less, more preferably 300 μm or less, and even more preferably 250 μm or less. The thickness of the light diffuser 1a is, for example, 50 μm or more.

[0017] As shown in Figure 1A, the light diffuser 1a may be composed of, for example, only a light diffusing layer 10. In this case, the light diffusing layer 10 may be called a light diffusing film or light diffusing film. Furthermore, although Figure 1A shows a substantially parallel plate-shaped light diffuser formed only of a light diffusing material such as the light diffusing layer 10, optical elements such as lenses, mirrors, diffraction gratings, and optical windows may be formed only of such light diffusing materials. The shape of the light diffuser 1a formed only of the light diffusing layer 10 is not particularly limited. In addition, the light diffuser 1a may be in the shape of a fiber formed only of a light diffusing material.

[0018] As shown in Figure 1B, the light diffuser 1a may have a configuration in which the light diffusing layer 10 is provided on the surface of the substrate 20. In this case, the light diffusing layer 10 may be positioned in contact with the substrate 20. One or more other layers may be provided between the substrate 20 and the light diffusing layer 10 in the thickness direction of the light diffusing layer 10, and the light diffusing layer 10 may be provided so as to be in contact with the surface of the other layers. The light diffuser 1a may have other layers in addition to the light diffusing layer 10.

[0019] In the light diffuser 1a, the substrate 20 supports the light diffusing layer 10. The shape of the substrate 20 and the properties of the surface of the substrate 20 in contact with the light diffusing layer 10 are not limited to any particular properties. The substrate 20 may be any article having various shapes, and may have a surface with irregularities ranging in size from 1 μm to 1000 μm or from 1 nm to 1000 nm. The surface of the substrate 20 may include flat surfaces, curved surfaces, or both flat and curved surfaces.

[0020] An example of the substrate 20 is a flat plate. In this case, substrates 20 of various thicknesses and sizes can be prepared inexpensively. In addition, the substrate 20 is easy to handle, and the formation of the light diffusion layer 10 can be relatively easy. When the substrate 20 is a flat plate, the thickness of the substrate 20 is, for example, 500 μm or less, preferably 400 μm or less, more preferably 300 μm or less, even more preferably 200 μm or less, and particularly preferably 100 μm or less. The thickness of the substrate 20 is, for example, 50 μm or more.

[0021] An example of the substrate 20 is an optical element. Examples of optical elements, though not limited to these, include refractive optical elements such as lenses, reflective optical elements such as mirrors, diffractive optical elements such as diffraction gratings, and optical windows. For example, a lens can exhibit light-gathering and diverging properties depending on its application. For example, by providing a light-diffusing layer 10 on the surface of a lens, the light-gathering and diverging properties of the lens, which is the substrate 20, can be enhanced. In particular, by providing a light-diffusing layer 10 on the surface of a lens system or lens used in an application that exhibits diverging properties, an improvement in light diffusion or an improvement in the uniformity of light intensity or illuminance can be expected.

[0022] An example of the substrate 20 may be a photoelectric conversion element included in the sensor, or a component or member that forms part of it. In this case, the light-receiving surface of the photoelectric conversion element may be considered as the surface of the substrate 20. The light diffuser 1a may be placed at a distance from the sensor, but providing the light diffusion layer 10 on the surface or window of the light-receiving surface of a photoelectric conversion element such as a photodiode (PD) or avalanche photodiode (APD) can contribute to reducing the assembly process and lowering the height of the product.

[0023] The substrate 20 includes, for example, glass. The glass used as the material for the substrate 20 is not limited to these, but includes soda-lime glass (including glass manufactured by the float process), borosilicate glass such as Pyrex® and D263, silica glass, quartz glass, alkali barium glass, aluminoborosilicate glass, borate glass, lead glass (including crystal glass), titanium silicate glass, alkali-free glass, ceramic glass, and optical glass. Examples of optical glass include holographic crown glass (BK7, etc.), crown glass (K11, etc.), zinc crown glass (ZK7, etc.), barium crown glass (BaK4, etc.), heavy crown glass (SK5, etc.), crown flint glass (KF1, etc.), flint glass (F2, etc.), heavy flint glass (SF11, etc.), light barium flint glass (BaLF1, etc.), barium windshield (BaF11, etc.), heavy barium flint glass (BaSF6, etc.), light lanthanum glass (LaLK1, etc.), lanthanum glass (LaK9, etc.), light lanthanum flint glass (LaLF6, etc.), lanthanum flint glass (LaF2, etc.), phosphate crown glass (PSKS1, etc.), titanium flint glass (TiF6, etc.), and refractive index distributed glass (SELFOC®, etc.).

[0024] The substrate 20 may contain light-absorbing glass. Examples of light-absorbing glass include cadmium selenide glass, telluride selenide glass, phosphate glass, and fluorine phosphate glass. The substrate 20 may also contain, for example, a resin. Examples of resins included in the substrate 20 include cycloolefin resins such as norbornene-based resins, polyarylate resins, acrylic resins, modified acrylic resins, polyimide resins, polyetherimide resins, polyolefin resins, polysulfone resins, polyethersulfone resins, polycarbonate resins, and silicone resins. Resins are easier to process and mold than glass. Therefore, when the substrate 20 contains a resin, it is easy to obtain substrates 20 in various shapes.

[0025] The material of the substrate 20 may be, for example, a material included in the sensor. In this case, examples of materials for the substrate 20 are silicon (Si), gallium arsenide (GaAs), indium gallium arsenide (InGaAs), germanium (Ge), indium phosphide (InP), silicon carbide (SiC), and gallium nitride (GaN).

[0026] The optical properties of the substrate 20 are not limited to specific optical properties, as long as they can achieve the light diffusion and light absorption properties required for the light diffuser 1a. For example, the substrate 20 itself may have light diffusion properties, such as milky glass and opal plates. On the other hand, in order to improve and maintain the efficiency of light utilization, it is desirable that the total light transmittance of the substrate 20 be high. Furthermore, in the transmission spectrum of the transmitted light of the substrate 20, the average value of the transmittance in the visible light range is preferably 80% or more, and more preferably 85% or more.

[0027] As long as the light diffuser 1a transmits a portion of visible light and absorbs a portion of near-infrared light, the light diffusing layer 10 is not limited to a specific layer. In the light diffuser 1a, the light diffusing layer 10 has, for example, light absorbing properties in addition to light diffusing properties. For example, a portion of near-infrared light can be absorbed by the light diffusing layer 10.

[0028] As shown in Figure 1A, the light diffusion layer 10 includes, for example, light-absorbing particles 12. The light absorption characteristics of the light-absorbing particles 12 are not limited to specific light absorption characteristics, as long as the light diffuser 1a transmits a portion of the visible light and absorbs a portion of the near-infrared light. The light-absorbing particles 12 absorb light in a specific wavelength range, for example. This allows the light diffusion layer 10 to absorb a portion of the near-infrared light. In addition, the light-absorbing particles 12 do not absorb light in wavelength ranges other than the specific wavelength range mentioned above, for example. This allows the light diffuser 1a to transmit a portion of the visible light.

[0029] The light-diffusing layer 10 can be formed, for example, by curing a liquid composition containing light-absorbing particles 12 and a solvent.

[0030] As shown in Figure 1A, the light diffusion layer 10 further comprises a binder 14 that encapsulates and fixes light-absorbing particles 12 inside the light diffusion layer 10. The binder 14 comprises at least one selected from the group consisting of polymers and resins. The above liquid composition may contain a precursor of the binder 14.

[0031] The light-absorbing particles 12 may, for example, have light-diffusing properties. This allows the light-diffusing layer 10 to exhibit desired light-diffusing properties. The average particle diameter of the light-absorbing particles 12 is not limited to a specific value. The average particle diameter of the light-absorbing particles 12 may, for example, correspond to the wavelength of light to be diffused. The average particle diameter of the light-absorbing particles 12 is, for example, 0.1 μm or more. When the average particle diameter is 0.1 μm or more, the light-diffusing layer 10 is more likely to exhibit desired light-diffusing properties, and preferably it is 0.2 μm or more. Furthermore, the average particle diameter of the light-absorbing particles 12 is, for example, 10 μm or less. When the average particle diameter is 10 μm or less, it is easier to avoid the light absorption of the light-diffusing layer 10 becoming too high and the transmittance becoming excessively low, and in addition, moiré patterns are less likely to occur. The average particle diameter of the light-absorbing particles 12 is preferably 1 μm or less. The light-absorbing particles 12 may exist as primary particles, as secondary particles formed by the aggregation of primary particles, as higher-order particles formed by further aggregation and growth, or as a mixture of these. In other words, the concept of light-absorbing particles 12 includes primary particles, secondary particles formed by the aggregation of primary particles, higher-order particles formed by the aggregation of those secondary particles, and any combination thereof. Even if the primary light-absorbing particles 12 do not have an average particle diameter capable of causing light scattering, the secondary particles formed by the aggregation of those primary particles, and the higher-order light-absorbing particles 12, may have an average particle diameter capable of causing light scattering. Furthermore, the primary light-absorbing particles 12 may have an average particle diameter capable of causing light scattering.

[0032] The light-absorbing particles 12 include, for example, copper complexes. The divalent copper component that may be included in the copper complex can absorb some light belonging to the near-infrared region through light absorption by d-d transitions in the electron orbitals. On the other hand, the divalent copper component that may be included in the copper complex is relatively less likely to absorb light of wavelengths belonging to the visible light region. Examples of such copper complexes are compounds containing a sulfur oxide component and a copper component, and compounds containing a phosphorus oxide component and a copper component. Here, the sulfur oxide component is a component obtained by modifying a raw material that contains sulfur oxides, and is responsible for the formation of compounds with the copper component. The phosphorus oxide component is a component obtained by modifying a raw material that contains phosphorus oxides, and is responsible for the formation of compounds with the copper component. Furthermore, the copper component is a concept that includes copper atoms and / or copper ions, etc., and is obtained using copper-containing raw materials such as copper oxide and copper acetate, and is responsible for the formation of compounds with each oxide.

[0033] Examples of sulfur oxide components include sulfonic acid components, sulfinic acid components, and sulfonic acid ester components. Examples of phosphorus oxide components include phosphonic acid components, phosphinic acid components, phosphonic acid ester components, orthophosphate components, pyrophosphate components, polyphosphate components, metaphosphate components, or M n Cu y PO 4-z This is a copper phosphate complex represented by (where M is a metal element other than Cu). n is an integer greater than or equal to 1, y is an integer greater than or equal to 1, and z is 1, 2, or 3.

[0034] The light-absorbing particles 12 may, for example, contain a phosphonic acid component and a copper component. In this case, the light-diffusing layer 10 may have high absorption capacity for light in the near-infrared region and low absorption capacity for light in the visible light region.

[0035] If the light-absorbing particles 12 contain a phosphonic acid component and a copper component, the light-absorbing particles 12 may also contain a product obtained by mixing and reacting a copper compound, such as copper acetate, copper benzoate, and copper formate, with phosphonic acid in the presence of a phosphate ester. This product is not certain, but it is presumed to be a compound containing at least a phosphonic acid component and a copper component, with high absorption capacity for light in the near-infrared region and low absorption capacity for light in the visible light region, and containing a divalent copper ion or an equivalent component. Alternatively, the light-absorbing particles 12 may be a collection or aggregation of one or more compounds that arbitrarily contain these components.

[0036] The phosphonic acid described above is not limited to a specific phosphonic acid. For example, the phosphonic acid may include a phosphonic acid represented by the following formula (a). In formula (a), R1 is an alkyl group or a halogenated alkyl group in which at least one hydrogen atom in the alkyl group is substituted with a halogen atom. In this case, the transmission band of the light diffuser 1a equipped with the light diffusion layer 10 tends to extend to a wavelength of around 700 nm. In addition, the light diffuser 1a tends to have the desired transmission characteristics. The phosphonic acid represented by formula (a) is referred to as the first phosphonic acid.

[0037]

[0038] Examples of primary phosphonic acids include methylphosphonic acid, ethylphosphonic acid, n-(n-)propylphosphonic acid, isopropylphosphonic acid, n-(n-)butylphosphonic acid, isobutylphosphonic acid, sec-butylphosphonic acid, tert-butylphosphonic acid, hexylphosphonic acid, octylphosphonic acid, and bromomethylphosphonic acid.

[0039] The phosphonic acid may include a phosphonic acid represented by the following formula (b). In formula (b), R2 is an aryl group, an aryl halide in which at least one hydrogen atom in the aryl group is substituted with a halogen atom, a group in which at least one hydrogen atom in the aryl group is substituted with a nitro group, or a group in which at least one hydrogen atom in the aryl group is substituted with a hydroxyl group. An aryl group is, for example, a phenyl group. An aryl halide is, for example, a phenyl halide. The use of such a phosphonic acid makes it easier for the light diffuser 1a equipped with the light diffusion layer 10 to have the desired transmission properties. The phosphonic acid represented by formula (b) is called a secondary phosphonic acid.

[0040]

[0041] Examples of secondary phosphonic acids include phenylphosphonic acid, bromophenylphosphonic acid, benzylphosphonic acid, fluorophenylphosphonic acid, iodophenylphosphonic acid, nitrophenylphosphonic acid, hydroxyphenylphosphonic acid, tolylphosphonic acid, xylylphosphonic acid, and naphthylphosphonic acid.

[0042] The light-absorbing particles 12 may contain only a primary phosphonic acid component, only a secondary phosphonic acid component, or both a primary and a secondary phosphonic acid component. The light-absorbing particles 12 may contain only one type or two or more types of primary phosphonic acid components, or they may contain only one type or two or more types of secondary phosphonic acid components, or they may contain phosphonic acid components other than the primary and secondary phosphonic acid components. In the light-absorbing particles 12 contained in the above liquid composition, the primary phosphonic acid component and the secondary phosphonic acid component may each be bound to a copper component.

[0043] The copper component is a concept that includes copper ions, copper complexes, and compounds containing copper. In the light diffusion layer 10, the copper component can contribute, for example, to good absorption characteristics for a portion of the light belonging to the near-infrared region and high transmittance of light in the visible light range of 450 nm to 680 nm. Details are omitted, but divalent copper ions Cu2+ When it adopts a six-coordinate complex structure, light of a corresponding energy wavelength is absorbed in relation to electron transitions between d orbitals with different energy levels. Divalent copper ions absorb light in a relatively broad wavelength range belonging to the infrared spectrum, so they can exhibit a highly valuable light-absorbing function in optical elements used, for example, in the fields of digital photography and ambient light sensors. The width of the absorption band and the intensity of absorption depend largely on the structure, strain, and properties of the ligands that coordinate to the copper ions. For these reasons, the light-absorbing particles 12 preferably contain a compound in which phosphorus-containing compounds such as phosphonic acid components and phosphate ester components are coordinated to the copper ions. This makes it easier to adjust the luminous sensitivity in products equipped with the light diffuser 1a.

[0044] The source of the copper component contained in the light-absorbing particles 12 is not limited to a specific substance. Examples of copper component sources include anhydrous or hydrated copper salts of organic acids such as copper acetate, copper benzoate, copper pyrophosphate, and copper stearate, or mixtures thereof. Among these, copper acetate or copper benzoate is preferably used. These copper salts may be used individually, or multiple copper salts or mixtures thereof may be used.

[0045] The above liquid composition may contain a phosphate ester. For example, if the light-absorbing particles 12 contain a phosphonic acid component, the phosphate ester is a compound that contains phosphorus and oxygen atoms, similar to the phosphonic acid component, and is therefore expected to have good compatibility with the phosphonic acid component. The phosphate ester may function as a dispersant for the light-absorbing particles 12 in the liquid composition, or it may exist in a state where a modified portion of the phosphate ester component has reacted with a metal component such as copper ions to form a compound. For example, a portion of the phosphate ester component may be coordinated to the light-diffusing particles, or a portion may form a complex with the copper component of the light-diffusing particles. In this case, the compound containing the phosphate ester component and the copper component can also absorb light of a predetermined wavelength.

[0046] The phosphate ester is not limited to a specific phosphate ester. The phosphate ester contains at least one selected from the group consisting of a phosphodiester represented by the following formula (c1) and a phosphomonoester represented by the following formula (c2). In the following formula (c1) and the following formula (c2), R 21 , R 22 , and R3 are each a monovalent functional group represented by -(CH2CH2O) n R4, n is an integer from 1 to 25, and R4 represents an alkyl group having 6 to 25 carbon atoms. R 21 , R 22 , and R3 are functional groups of the same or different types from each other.

[0047]

[0048] Examples of the phosphate ester include Plisurf A208N: polyoxyethylene alkyl (C12, C13) ether phosphate ester, Plisurf A208F: polyoxyethylene alkyl (C8) ether phosphate ester, Plisurf A208B: polyoxyethylene lauryl ether phosphate ester, Plisurf A219B: polyoxyethylene lauryl ether phosphate ester, Plisurf AL: polyoxyethylene styrenated phenyl ether phosphate ester, Plisurf A212C: polyoxyethylene tridecyl ether phosphate ester, and Plisurf A215C: polyoxyethylene tridecyl ether phosphate ester. All of these are products manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Another example of the phosphate ester is NIKKOL DDP-2: polyoxyethylene alkyl ether phosphate ester, NIKKOL DDP-4: polyoxyethylene alkyl ether phosphate ester, and NIKKOL DDP-6: polyoxyethylene alkyl ether phosphate ester. All of these are products manufactured by Nikko Chemicals Co., Ltd. These phosphate ester compounds may be used alone or in combination of a plurality.

[0049] As described above, the light diffusion layer 10 may contain a resin. In this case, the liquid composition that is a precursor of the light diffusion layer 10 may contain a resin before curing. Examples of resins include curable resins, curable polymers, and monomers, dimers, or oligomers that are precursors of curable polymers. Curable resins are liquid in an uncured or unreacted state. In addition, as curable resins, preferably, those that can form a coating film by applying the liquid composition onto the surface of a predetermined substrate by coating methods such as spin coating, spraying, dipping, and application with a dispenser may be selected. As curable resins, preferably, those in which the surface formed by curing the curable resin is smooth and the transmittance in the wavelength range of 450 nm to 800 nm in the transmission spectrum of a plate-like body with a thickness of 1 mm is 80% or more. Examples of curable resins include cyclic polyolefin resins, epoxy resins, polyimide resins, modified acrylic resins, silicone resins, and polyvinyl resins such as PVB, or their precursors. These curable resins may be used individually, or multiple types of curable resins may be used in combination.

[0050] The above liquid composition and light diffusion layer 10 may contain at least one selected from the group consisting of a metal alkoxide represented by the following formula (D), a hydrolysate of the metal alkoxide, and a polymer of the hydrolysate. M is an element selected from the group consisting of Li, Na, K, Mg, Ca, Sr, Ba, B, Al, Ga, Si, Ge, P, Sb, La, Nd, V, Y, Bi, Ti, Zr, Nb, and Ta, and R 51 R is an organic group or a hydrogen atom, directly bonded to the M atom. 52 (R) is a hydrocarbon group containing 1 to 20 carbon atoms (C), and n is an integer from 1 to 4. 51 ) 4-n -M-(OR 52 ) n (D)

[0051] The light diffusion layer 10 contains, for example, a silicon compound. In this case, excessive aggregation of light-absorbing particles 12 in the light diffusion layer 10 is easily prevented. In this case, for example, the liquid composition may contain at least one selected from the group consisting of alkoxysilane, hydrolysate of alkoxysilane, and polymer of hydrolysate of alkoxysilane. In this case, the liquid composition may include alkoxysilane monomer, a part of the alkoxysilane monomer that has been hydrolyzed, and a polymer in which at least a part of the hydrolysate of alkoxysilane has been polymerized. For example, in the above formula (D), when M is a silicon (Si) atom, the metal alkoxide is an alkoxysilane.

[0052] The liquid composition and the light diffusion layer 10 may contain, for example, at least one selected from the group consisting of an alkoxysilane represented by the following formula (d), a hydrolysate of the alkoxysilane, and a polymer of the hydrolysate of the alkoxysilane. In formula (d), preferably n is an integer from 1 to 4, and more preferably n is an integer from 2 to 4. The alkoxysilane represented by formula (d) is a difunctional alkoxysilane (n=2), a trifunctional alkoxysilane (n=3), or a tetrafunctional alkoxysilane (n=4). Difunctional, trifunctional, and tetrafunctional indicate having two, three, and four alkoxy groups in one molecule, respectively. In formula (d), R 61 and R 62 They may be the same or different from each other, R 61 and R 62 Each of these is a group comprising at least a carbon atom (C) and a hydrogen atom (H), and may be, for example, an alkyl group, an aryl group, or a cyclic hydrocarbon group. In this specification, a cyclic hydrocarbon group is a hetero or homo cyclic hydrocarbon group. 61 and R 62 Each of these may be an alkyl group, an aryl group, or a cyclic hydrocarbon group in which one or more hydrogen atoms are substituted with a halogen atom, a nitro group, an amino group (including derivatives), or a hydroxyl group. 61 and R 62Each of these may be a branched group or an unbranched group. Also, in equation (d), R 61 It is not necessary. (R 61 ) 4-n -Si-(OR 62 ) n Formula (d)

[0053] In a liquid composition, the inclusion of an alkoxysilane represented by formula (d), a hydrolysate of this alkoxysilane, or a polymer of this alkoxysilane hydrolysate facilitates the formation of a network when the liquid composition is cured. - (OR 62 The group represented by ) is an alkoxy group. For example, when forming a light diffusion layer 10 using a liquid composition, siloxane bonds (-Si-O-Si-) are formed by processing to ensure that the hydrolysis and condensation polymerization reactions of the alkoxysilane occur sufficiently. As a result, the light diffusion layer 10 tends to have good moisture resistance. In addition, the light diffusion layer 10 has good heat resistance. This is because siloxane bonds have higher bond energy and are chemically more stable than bonds such as -C-C- bonds and -C-O- bonds, and therefore have excellent heat resistance and moisture resistance. By condensation polymerization after hydrolysis of the alkoxysilane, for example, oligomers or low molecular weight silicone resins (siloxane oligomers and liner siloxanes, etc.), organically modified siloxane structures, and inorganic silica structures (silica gel, amorphous silica, and siloxane networks, etc.) can be produced in a mixed state.

[0054] In particular, trifunctional alkoxysilanes and tetrafunctional alkoxysilanes undergo condensation polymerization after hydrolysis to produce compounds having the structures of (poly)silsesquioxane and silica, respectively.

[0055] The alkoxysilane contained in the liquid composition may include a primary alkoxysilane that does not contain a hydrocarbon group having 10 or more carbon atoms in one molecule. The primary alkoxysilane is, for example, in formula (d), R 61 It may also be an alkoxysilane containing fewer than 10 carbon atoms (C). In formula (d), R 61It does not have to exist, or R 61 and R 62 At least one of the groups may include a carbon atom (C) and a hydrogen atom (H). 61 and R 62 At least one of them may be an alkyl group, an aryl group, or a cyclic hydrocarbon group. 61 and R 62 At least one of the groups may be an alkyl group, an aryl group, or a cyclic hydrocarbon group in which one or more hydrogen atoms are substituted with a halogen atom, a nitro group, an amino group (including derivatives), or a hydroxyl group. 61 and R 62 At least one of the groups may be a branched group or an unbranched group. n is an integer from 1 to 4. The liquid composition may contain one or more types of first alkoxysilanes.

[0056] The first alkoxysilane is not limited to these, but may be a tetrafunctional alkoxysilane such as tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetratert-butoxysilane, and tetracyclopentoxysilane; or a trifunctional alkoxysilane such as methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isopropyltrimethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, and allyltrimethoxysilane; or a difunctional alkoxysilane such as dimethyldimethoxysilane, dimethyldiethoxysilane, methylphenyldimethoxysilane, methylvinyldimethoxysilane, ethylmethyldimethoxysilane, cyclohexylmethyldimethoxysilane, propylmethyldimethoxysilane, and benzylmethyldimethoxysilane.

[0057] From the viewpoint of improving the density of the light diffusion layer 10, the liquid composition preferably contains a tetrafunctional alkoxysilane as the primary alkoxysilane, and more preferably contains a tetraethoxylan. Furthermore, when the liquid composition contains a tetrafunctional alkoxysilane, further containing a trifunctional alkoxysilane or a difunctional alkoxysilane makes it easier to impart flexibility to the light diffusion layer 10, and is expected to prevent or suppress cracks or fissures during the curing of the liquid composition, and improve the temperature cycle characteristics and moisture resistance of the light diffusion layer 10.

[0058] The alkoxysilane contained in the liquid composition may include a secondary alkoxysilane containing a hydrocarbon group having 10 or more carbon atoms in one molecule. In this case, since the secondary alkoxysilane has a relatively long carbon chain, excessive aggregation of light-absorbing particles 12 is more easily prevented, and the generation of appropriate secondary or tertiary particles can be promoted.

[0059] The secondary alkoxysilane is not limited to these, but may be a trifunctional alkoxysilane such as decyltrimethoxysilane, dodecyltrimethoxysilane, tridecyltrimethoxysilane, tetradecyltrimethoxysilane, pentadecyltrimethoxysilane, hexadecyltrimethoxysilane, dodecyltriethoxysilane, octadecyltrimethoxysilane, and decylphenyltrimethoxysilane, or a difunctional alkoxysilane such as didecyldimethoxysilane, didodecyldimethoxysilane, decyldodecyldimethoxysilane, ditridecyldimethoxysilane, dodecylphenyldimethoxysilane, decylphenyldimethoxysilane, octadecyldimethyldiethoxysilane, tridecylphenyldimethoxysilane, and decylundecyldiethoxysilane. In these alkoxysilanes, the alkoxy group may be linear or branched.

[0060] The molar ratio r of the second content to the copper atom content in the liquid composition 2 / CuThe second content is not limited to a specific value. The second content is the total amount of the content of the secondary alkoxysilane, the content of the hydrolysate of the secondary alkoxysilane converted to the content of the secondary alkoxysilane, and the content of the polymer of the hydrolysate of the secondary alkoxysilane converted to the content of the secondary alkoxysilane. Molar ratio r 2 / Cu For example, this is 0.3 to 4. In this case, the above-mentioned advantages of including a secondary alkoxysilane are more easily obtained.

[0061] Mole ratio r 2 / Cu Preferably, it is 0.4 to 3.9, more preferably 0.4 to 3.8, and even more preferably 0.5 to 3.8.

[0062] The alkoxysilane contained in the liquid composition may contain only a primary alkoxysilane, only a secondary alkoxysilane, or both a primary and a secondary alkoxysilane. Preferably, the alkoxysilane contained in the liquid composition contains both a primary and a secondary alkoxysilane. This improves the density, flexibility, temperature cycle characteristics, and moisture resistance of the light diffusion layer 10, prevents or suppresses cracks or fissures during the curing of the liquid composition, and makes it easier to prevent excessive aggregation of light-absorbing particles 12, thereby promoting the generation of appropriate secondary or tertiary particles.

[0063] If the liquid composition contains both a primary alkoxysilane and a secondary alkoxysilane, the molar ratio r of the primary content to the secondary content is... 1 / 2 This is not limited to a specific value. The first content is the total amount of the first alkoxysilane, the hydrolysate of the first alkoxysilane converted to the amount of the first alkoxysilane, and the polymer of the hydrolysate of the first alkoxysilane converted to the amount of the first alkoxysilane. The second content is the total amount of the second alkoxysilane, the hydrolysate of the second alkoxysilane converted to the amount of the second alkoxysilane, and the polymer of the hydrolysate of the second alkoxysilane converted to the amount of the second alkoxysilane. Molar ratio r 1 / 2For example, this value is 0.5 to 2. In this case, excessive dispersion of the light-absorbing particles 12 is easily suppressed, and excessive aggregation is also easily suppressed.

[0064] Mole ratio r 1 / 2 Preferably, it is 0.6 to 1.8, more preferably 0.7 to 1.6, and even more preferably 0.8 to 1.6.

[0065] The liquid composition does not need to contain curable resins other than alkoxysilane or alkoxysilane-derived compositions. This is because the alkoxysilane polymerizes while the light-absorbing particles 12 are present in the desired state, and further condensation polymerization is performed to form a network containing silicon dioxide. If the liquid composition contains the tetrafunctional alkoxysilane contained in the alkoxysilane represented by formula (d), an improvement in the density or hardness of the light-diffusing layer 10 can be expected. The alkoxysilane represented by formula (d) can be solidified by increasing its molecular weight through alkoxysilane hydrolysis and condensation polymerization of siloxane bonds using the so-called sol-gel method. In addition, the liquid composition can harden as a dry gel when the solvent or by-products contained in the liquid composition are removed by evaporation or the like. It is not possible to uniquely determine which effect is dominant, but it is thought that various effects and processes are involved, including the effect of suppressing the excessive aggregation of light-absorbing particles 12.

[0066] The liquid composition may contain an ultraviolet absorber that absorbs some of the light belonging to the near-ultraviolet range. In this specification, near-ultraviolet light is light having wavelengths in the range of 300 nm to 400 nm. The ultraviolet absorber is not limited to a specific compound. Preferably, the ultraviolet absorber is selected from the viewpoint of absorbing light in a desired wavelength range, being compatible with a specific solvent, or at least not agglomerating, dispersing well in the liquid composition, and having excellent environmental resistance. Examples of ultraviolet absorbers are benzophenone compounds, benzotriazole compounds, salicylic acid compounds, and triazine compounds. For example, Tinuvin PS, Tinuvin 99-2, Tinuvin 234, Tinuvin 326, Tinuvin 329, Tinuvin 900, Tinuvin 928, Tinuvin 405, and Tinuvin 460 can be used as ultraviolet absorbers. These are UV absorbers manufactured by BASF, and Tinuvin is a registered trademark.

[0067] The liquid composition may contain a predetermined solvent. The solvent is not limited to a specific solvent. The solvent may be an organic solvent. The organic solvent is not limited to a specific organic solvent. Examples of organic solvents may be alcohols, xylenes, or cyclic compounds. Examples of alcohols include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, 2-butanol, t-butanol, n-pentanol, i-pentanol, 2-methylbutanol, 2-pentanol, t-pentanol, 3-methoxybutanol, n-hexanol, 2-methylpentanol, 1-hexanol, 2-hexanol, 2-ethylbutanol, 1-heptanol, 2-heptanol, 3-heptanol, n-octanol, 2-ethylhexanol, 2-octanol, n-nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, cyclohexanol, methylcyclohexanol, 3,3,5-trimethylcyclohexanol, benzyl alcohol, and diacetone alcohol. Examples of cyclic compounds include dichlorobenzene, heptanone, cyclopentanone, cyclohexanone, cyclohexane, dimethylformamide, dimethylacetamide, toluene, tetrahydrofuran (THF), and oxetane.

[0068] The molar ratio r of the copper (Cu) atom content to the silicon (Si) atom content in the liquid composition and the light diffusion layer 10. C / S This is not limited to a specific value. (molar ratio r) C / S For example, the molar ratio r is between 0.1 and 1. C / S When the molar ratio r is 0.1 or higher, the light diffusion layer 10 is more likely to exhibit the desired light absorption characteristics. C / S By keeping the value below 1, it is easier to avoid the haze of the light diffuser 1a becoming excessively low. Molar ratio r C / S The value is preferably between 0.15 and 0.9.

[0069] The molar ratio r of phosphorus (P) atoms to silicon (Si) atoms in the liquid composition and the light diffusion layer 10. P / S This is not limited to a specific value. (molar ratio r) P / SFor example, the molar ratio r is 0.15 to 1.5. P / S When the molar ratio r is 0.15 or higher, the light diffusion layer 10 is more likely to exhibit the desired light absorption characteristics. P / S By keeping the molar ratio r below 1.5, it is easier to avoid the haze of the light diffuser 1a becoming excessively low. P / S Preferably, it is 0.15 to 1.4, more preferably 0.15 to 1.3, and even more preferably 0.18 to 1.2.

[0070] The light-diffusing layer 10 is obtained by curing the above liquid composition. The light-diffusing layer 10 and the light-diffusing body 1a equipped with the light-diffusing layer 10 may be manufactured by applying the liquid composition to the surface of the substrate 20, curing it, and fixing it in place. Alternatively, a light-diffusing body 1a consisting only of the light-diffusing layer 10 may be manufactured by applying the liquid composition to the surface of a predetermined object, curing it, and fixing it in place. Or, a light-diffusing body 1a consisting only of the light-diffusing layer 10 may be manufactured by applying the liquid composition to the surface of the substrate, curing it, and then peeling off only the light-diffusing layer 10 from the surface of the substrate.

[0071] The method for applying or coating a liquid composition onto a substrate is not limited to any particular method. Examples of this method include the solvent casting method (solution casting method), in which the liquid composition is cast onto the surface of a substrate or object to obtain a substantially uniform coating film; the spray coating method, in which the liquid composition is atomized and sprayed onto the substrate or object; the dipping coating method, in which the substrate or object is immersed in the liquid composition and then withdrawn to form a coating film; the spin coating method, in which the liquid composition is dropped onto a rotating substrate or object and a substantially uniform coating film is formed using centrifugal force; the rotary coating method, in which the liquid composition is continuously applied to the surface of a substrate or object using a rotating applicator to form a coating film; and the dispenser method, in which the liquid composition is dropped onto the surface of a substrate or object using a syringe or dispenser while scanning the surface of the substrate or object to form a coating film.

[0072] The thickness of the light diffusion layer 10 is not limited to a specific value. For example, the thickness of the light diffusion layer 10 is 50 to 400 μm. When the thickness of the light diffusion layer 10 is 50 μm or more, the desired light diffusion and light absorption characteristics are more easily exhibited. When the thickness of the light diffusion layer 10 is 400 μm or less, the component or element equipped with the light diffusion layer 10 is more easily able to meet the requirement for a low profile product. Preferably, the thickness of the light diffusion layer 10 is 70 to 350 μm.

[0073] The light diffusion layer 10 or light diffuser 1a has, for example, a haze of 20% or more. In this case, for example, when the light diffuser 1a is incorporated into an ambient light sensor, it may not be possible to sense the light in a sufficient field of view in front of the ambient light sensor. Preferably, the light diffusion layer 10 or light diffuser 1a has a haze of 20% to 50%. By having a haze of 50% or less, it is easier to avoid the visible light transmittance of the light diffusion layer 10 or light diffuser 1a becoming excessively low, and it is easier to avoid the desired performance not being achieved due to a decrease in the light beam reaching the target object such as a sensor.

[0074] The total transmitted light from light in the wavelength range of 300 nm to 1200 nm incident on the light diffuser 1a at an incident angle of 0° has a first transmission spectrum that satisfies, for example, the following requirements (i) and (ii). The first transmission spectrum may be measured, for example, in accordance with JIS K 7375:2008 using instruments capable of measuring according to said standard. (i) Average value T of transmittance in the wavelength range of 450 nm to 600 nm ave (ii) The maximum value of transmittance T in the wavelength range of 800 nm to 1000 nm. IRMAX The percentage is 15% or less.

[0075] Regarding requirement (i), the wavelength range of 450 nm to 600 nm is an important range of the wavelength range corresponding to the visible light spectrum. Average value T ave When this is 50% or more, for example, the amount of light that passes through the light diffuser 1a and reaches an object such as a sensor does not tend to decrease, and the object such as a sensor is more likely to exhibit the desired performance. Average value T ave The ideal percentage is between 50% and 75%. (Average value T) aveBy keeping the value below 75%, it is possible to avoid excessively low haze in the light diffusion layer 10 or light diffuser 1a, and the desired light diffusion performance can be easily achieved. Average value T ave More preferably, it should be between 50% and 72%.

[0076] Regarding requirement (ii), the maximum value T IRMAX Because the value is 15% or less, the transmittance in the near-infrared region, which is outside the visible light range, is less likely to be high, and the correspondence between brightness based on human visual sensitivity and the light receiving sensitivity of the sensor tends to be appropriate. Maximum value T IRMAX It is preferably 12% or less, and more preferably 10% or less.

[0077] The first transmission spectrum may, for example, satisfy the requirement of (iii) below. In this case, the transmittance in the near-infrared region is less likely to be higher than the transmittance in the visible light region, and the relationship between brightness based on human visual sensitivity and the light receiving sensitivity of the sensor tends to be appropriate. (iii) Maximum transmittance T in the wavelength range of 450 nm to 650 nm vismax The maximum transmittance T in the wavelength range of 800 nm to 1000 nm for [the specified value]. IRMAX ratio T IRMAX / T vismax It is 0.2 or less.

[0078] ratio T IRMAX / T vismax It is preferably 0.18 or less, and more preferably 0.16 or less.

[0079] The first transmission spectrum has, for example, a full width at half maximum (FWHM) of 200 nm to 380 nm. This makes it easier to maintain high transmittance in the wavelength range that roughly corresponds to the wavelength range corresponding to the visible light range. Preferably, in the first transmission spectrum, the mean value T ave The transmittance is 50% or more, and the FWHM is 200 nm to 380 nm. The FWHM of the first transmission spectrum is more preferably 220 nm to 380 nm, but may be 230 nm to 370 nm. Here, the full width at half maximum (FWHM) is the maximum wavelength at which the transmittance is 50% within the wavelength range of 350 nm to 750 nm (first cutoff wavelength: λ). LFrom this, the minimum wavelength at which the transmittance is 50% (second cutoff wavelength: λ) S It is calculated by subtracting the first cutoff wavelength (λ) in the first transmission spectrum. L The second cutoff wavelength (λ) is preferably in the range of 620 nm to 740 nm, and more preferably in the range of 640 nm to 720 nm. S The wavelength is preferably in the range of 360 nm to 440 nm, and more preferably in the range of 380 nm to 420 nm.

[0080] The light diffuser 1a is used, for example, in electronic devices equipped with a display. Examples of such electronic devices, but not limited to, include laptop computers, tablet computers, mobile phones, smartphones, smartwatches, media players, other handheld display devices, head-mounted displays, wearable displays, televisions, game consoles with displays, automobiles, ships, and other mobile devices equipped with displays, as well as navigation systems or devices and smart lighting systems. An ambient light sensor module equipped with the light diffuser 1a may also be mounted in the electronic device.

[0081] Figure 2 is a block diagram showing an example of an electronic device according to the present invention. As shown in Figure 2, the electronic device 3a comprises a display 31, an ambient light sensor 32, and a control device 33. The display 31 displays predetermined information. The display 31 may also be a light source such as an illuminator, in which case it may be read as "illumination device". The ambient light sensor 32 detects ambient light around the electronic device 3a. The control device 33 adjusts the brightness of the display 31 according to the output of the ambient light sensor 32. For example, if the current brightness of the display 31 is too low relative to the output of the ambient light sensor 32, the control device 33 increases the brightness of the display 31. If the current brightness of the display 31 is too high relative to the output of the ambient light sensor 32, the control device 33 decreases the brightness of the display 31. The control device 33 includes a control circuit for adjusting the brightness of the display 31. The control circuit may include a memory circuit and a processing circuit, etc., for supporting the operation of the electronic device 3a. The electronic device 3a may be equipped with sensors (detectors) such as proximity sensors, magnetic sensors, accelerometers, touch sensors, temperature sensors, pressure sensors, compasses, sound sensors, and microphones, as needed. In addition, the electronic device 3a may include electronic circuits or elements for performing various functions. Components that are unnecessary for explaining the operation of the present invention are not shown or described. Note that although ambient light sensors may also be called illumination sensors or optical sensors, they are synonymous in that they have the function of detecting the intensity of external light and converting it into an electrical signal for use.

[0082] Figure 3 is a perspective view showing an example of an electronic device according to the present invention. Figure 4 is a perspective view showing another example of an electronic device according to the present invention. The electronic device 3b shown in Figure 3 is a laptop computer, which is one embodiment of the electronic device 3a described above. The electronic device 3c shown in Figure 4 is a smartphone, which is another embodiment of the electronic device 3a described above.

[0083] As shown in Figure 3, in the electronic device 3b, which is a laptop computer, the ambient light sensor 32 is located, for example, above the display 31. The electronic device 3b is equipped with input devices such as a keyboard 34b and an input pad 35b.

[0084] As shown in Figure 4, in the electronic device 3c, which is a smartphone, the ambient light sensor 32 may be positioned, for example, outside the display 31 or adjacent to an inactive area R1 inside the display 31. The inactive area R1 is an area where no information is displayed.

[0085] In electronic devices 3b and 3c, for example, ambient light is detected by the ambient light sensor 32, and an output signal corresponding to the ambient light is sent from the ambient light sensor 32 to the control device 33. The control device 33 adjusts the brightness of the display 31 based on the output signal sent from the ambient light sensor 32. For example, since smartphones are operated both indoors and outdoors, the need for a function to adjust the brightness of the display according to the ambient light is considered to be higher in smartphones than in personal computers.

[0086] Figure 5 is a schematic cross-sectional view showing an example of an ambient light sensor. As shown in Figure 5, the ambient light sensor 32 comprises a light diffuser 1a and a photodetector 32s. The photodetector 32s receives light transmitted through the light diffuser 1a.

[0087] The ambient light sensor 32 shown in Figure 5 is, for example, positioned in a part of a smartphone display corresponding to the inactive area R1. The ambient light sensor 32 may have a similar structure in electronic devices other than smartphones.

[0088] As shown in Figure 5, the smartphone display includes an inactive area R1 and an active area R2. In the active area R2, information can be displayed and input can be received via touch (including actions to operate the smartphone such as tapping, double-tapping, long-pressing, and swiping; the same applies hereinafter).

[0089] In the inactive area, for example, a light-shielding layer 32m may be provided on the side opposite to the surface of the exposed display cover 32k by masking. Such a light-shielding layer 32m can perform a light-shielding function to prevent external light from unconditionally reaching the inside of the device.

[0090] A light-transmitting window region 32w is provided, surrounded by the light-shielding layer 32m. The light diffuser 1a is positioned in the window region 32w on the side opposite to the surface of the display cover 32k. The photodetector 32s is positioned to receive light that has passed through the window region 32w. The photodetector 32s includes light-receiving elements 32d such as PD and APD. Ambient light AL that has traveled toward the window region 32w can pass through the window region 32w.

[0091] Figure 6 is a schematic cross-sectional view showing a part of the ambient light sensor. As shown in Figure 6, ambient light AL is incident on the light diffuser 1a. The light diffuser 1a diffuses and transmits a portion of the visible light, and the emitted light DL reaches the light-receiving element 32d of the photodetector 32s. On the other hand, the light diffuser 1a absorbs a portion of the near-infrared light. If the light diffuser 1a is not present, light that passes through the window region 32w from around the electronic device and reaches the photodetector 32s directly is detected, so the incident angle θ of detectable light is limited. IA The range is limited. It is conceivable to increase the range of detectable light incidence angles by increasing the effective size of the photodetector 32s along with the size of the window region 32w. However, this modification is not practical as it would also increase the size of the electronic device. On the other hand, since the ambient light sensor 32 is equipped with a light diffuser 1a, the light transmitted through the light diffuser 1a is diffused, and the radiation intensity of the emitted light tends to become uniform in the in-plane direction. For this reason, relatively large incidence angles θ IA The light also passes through the window area 32w and is diffused by the light diffuser 1a, reaching the photodetector 32s. As a result, the ambient light sensor 32 can detect a wider range of ambient light around the electronic device, and the ambient light sensor 32 can contribute to more appropriate brightness adjustment of the display.

[0092] Figure 7 is a schematic cross-sectional view showing another example of an ambient light sensor.

[0093] In Figures 5 and 6, the ambient light sensor 32 is an example that includes a light diffuser 1a formed in contact with the display cover 32k, a light shielding layer 32m formed in contact with the display cover 32k, and a photodetector 32s. In addition, for example, the light diffuser may be separate from the display cover 32k (formed at a distance from it), and similarly, the light shielding layer may also be separate from the display cover 32k (formed at a distance from it), and the photodetector may be positioned in contact with the display cover 32k. The ambient light sensor may be composed of various combinations of such elements and components. The ambient light sensor may have a structure that allows it to be incorporated into electronic equipment and perform its function even if the elements and components are not pre-integrated. In this case, it could also be called the "ambient light sensor part of electronic equipment," but in this document, the term "ambient light sensor" will be used consistently from a functional standpoint.

[0094] On the other hand, while retaining almost all of the above functions, the ambient light sensor 32 may be configured such that at least the light diffuser 1a and the photodetector 32s are integrated or modularized together with the substrate 32b, as shown in Figure 7. In this case, it can be understood that the market distribution of the ambient light sensor would be facilitated.

[0095] The present invention will be described in more detail by reference to examples. However, the present invention is not limited to the following examples.

[0096] <Example 1> 4.500 g of copper acetate monohydrate (manufactured by Kanto Chemical Co., Ltd.) and 240 g of tetrahydrofuran (THF) (manufactured by Kanto Chemical Co., Ltd.) were mixed and stirred for 3 hours to obtain a copper acetate solution. 1.764 g of the phosphate ester compound Prysurf A208N (manufactured by Daiichi Kogyo Co., Ltd.) was added to the obtained copper acetate solution and mixed to obtain solution (1-A). Next, 0.610 g of phenylphosphonic acid (manufactured by Nissan Chemical Co., Ltd.) was mixed with 40 g of THF and stirred for 30 minutes to obtain solution (1-B). 3.660 g of 4-bromophenylphosphonic acid was mixed with 40 g of THF and stirred for 30 minutes to obtain solution (1-C). 0.758 g of n-butylphosphonic acid was mixed with 40 g of THF and stirred for 30 minutes to obtain solution (1-D).

[0097] Solution (1-A) was mixed with solutions (1-B), (1-C), and (1-D). Then, 21.720 g of n-decyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), a trifunctional alkoxysilane, and 13.920 g of tetraethoxysilane (manufactured by Kishida Chemical Co., Ltd.), a tetrafunctional alkoxysilane, were added, and the mixture was stirred for another minute to obtain solution (1-E). Next, 40 g of toluene (manufactured by Kanto Chemical Co., Ltd.) was added to solution (1-E), and the mixture was stirred at room temperature for one minute to obtain solution (1-F).

[0098] The above (1-F) solution was placed in a flask and heated in an oil bath (Tokyo Rikakikai Co., Ltd., model: OSB-2100) while being treated with a rotary evaporator (Tokyo Rikakikai Co., Ltd., model: N-1110SF) to advance the reaction and remove THF. The oil bath temperature was set to 85°C. After that, the treated liquid was removed from the flask. In this way, a liquid composition (1-G) according to Example 1 was obtained, containing a light-absorbing compound containing phosphonic acid and copper components, and an alkoxysilane (including hydrolysates of alkoxysilane and polymers of hydrolysates of alkoxysilane), which is a silicon-containing compound containing an n-decyl group. The amounts (contents) of each compound added in the preparation of liquid composition (1-G) according to Example 1 are shown in Tables 1A and 1B. Tables 1A and 1B also show the amounts (contents) of each compound added in the preparation of light-absorbing compositions according to other examples.

[0099] A borosilicate glass (manufactured by SCHOTT, product name: D263 Teco) with dimensions of 76 mm × 76 mm × 0.21 mm was used as the substrate, and a coating film of the light-absorbing composition (1-G) was formed on one main surface of the substrate using a dispenser. After the obtained coating film was thoroughly dried at room temperature, it was placed in an oven and heated in the range of room temperature to 85°C for about 6 hours to allow the reaction of the alkoxysilane to proceed sufficiently and to volatilize the organic solvent contained in the light-absorbing composition (1-G). Subsequently, the coating film was further cured for 8 hours in an environment of 85°C and 85% relative humidity to complete the reaction. In this way, a light-diffusing layer formed on the surface of the substrate according to Example 1 was obtained. In addition, a light diffuser according to Example 1 was obtained in which the light-diffusing layer according to Example 1 was formed on the surface of the substrate. Table 2 shows the relationship between the content of specific atoms and the content of specific components in the liquid composition (1-G) and the light-diffusing layer. The alkoxysilane content includes the content of alkoxysilane hydrolysates converted to alkoxysilane equivalents and the content of alkoxysilane polymers converted to alkoxysilane equivalents.

[0100] The haze of the light diffuser according to Example 1 was measured in accordance with JIS K 7136:2000 using a haze meter HM-65L2 manufactured by Murakami Color Technology Laboratory Co., Ltd. The results are shown in Table 3. As shown in Table 3, the haze value of the light diffuser according to Example 1 was 29.5%.

[0101] The thickness of the light diffusion layer according to Example 1 was measured using a laser displacement meter LK-H008 manufactured by Keyence Corporation. As shown in Table 3, the thickness of the light diffusion layer according to Example 1 was 227 μm.

[0102] Using a V-770 UV-Vis-Near-Infrared Spectrophotometer manufactured by JASCO Corporation, the transmission spectrum of the light diffuser according to Example 1 at an incident angle of 0° was measured in accordance with JIS K 7375:2008. Unless otherwise specified, the transmission spectrum was measured with the ambient temperature around the light diffuser adjusted to 22-25°C. Figure 8 shows the transmission spectrum of the light diffuser according to Example 1. Table 3 shows the characteristic values ​​of the optical conditions of the light diffuser at an incident angle of 0°.

[0103] <Examples 2-13> Liquid compositions and light diffusers according to Examples 2-13 were prepared using the same methods and conditions as in Example 1, except that the required compounds and their amounts were changed as shown in Tables 1A and 1B. The compounds newly used in Examples 2-13 were n-hexyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), n-hexadecyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), n-octadecyltrimethoxysilane (manufactured by Gellest), and silicone resin (KR-300, manufactured by Shin-Etsu Chemical Co., Ltd.). The haze of each light diffuser, the thickness of the light diffusion layer in each light diffuser, and the transmission spectrum of each light diffuser were measured or calculated in the same manner as in Example 1. The results are shown in Table 3. The transmission spectra of the light diffusers according to Examples 2-13 are shown in Figures 9-20, respectively.

[0104]

[0105]

[0106]

[0107]

Claims

1. A light diffuser having a light diffusing layer, which transmits a portion of visible light and absorbs a portion of near-infrared light, and has a haze of 20% or more.

2. The light diffuser according to claim 1, wherein the light diffusing layer includes light-absorbing particles.

3. The light diffuser according to claim 2, wherein the light-absorbing particles comprise a phosphonic acid component and a copper component.

4. The light diffusing body according to claim 3, wherein the light diffusing layer comprises a silicon compound.

5. The light diffuser according to claim 4, wherein the molar ratio of copper atoms to silicon atoms in the light diffusing layer is 0.1 to 1.

6. The light diffuser according to claim 4 or 5, wherein the molar ratio of phosphorus atoms to silicon atoms in the light diffusing layer is 0.15 to 1.

5.

7. The light diffuser according to any one of claims 1 to 6, wherein the total transmitted light for light in the wavelength range of 300 nm to 1200 nm incident on the light diffuser at an incident angle of 0° has a first transmission spectrum, and the first transmission spectrum satisfies the following requirements (i) and (ii): (i) the average transmittance in the wavelength range of 450 nm to 600 nm is 50% or more; (ii) the maximum transmittance in the wavelength range of 800 nm to 1000 nm is 15% or less.

8. The light diffuser according to claim 7, wherein the first transmission spectrum satisfies the following requirement (iii): (iii) The ratio of the maximum transmittance in the wavelength range of 800 nm to 1000 nm to the maximum transmittance in the wavelength range of 450 nm to 650 nm is 0.2 or less.

9. The light diffuser according to claim 7 or 8, wherein the first transmission spectrum has a full width at half maximum of 200 nm to 380 nm.

10. The light diffusing body according to any one of claims 1 to 9, wherein the light diffusing layer has a thickness of 50 to 400 μm.

11. A liquid composition comprising light-absorbing particles and a solvent, wherein the liquid composition hardens to form a light-diffusing layer.

12. The liquid composition according to claim 11, wherein the light-absorbing particles comprise a phosphonic acid component and a copper component.

13. The liquid composition according to claim 12, comprising at least one selected from the group consisting of alkoxysilanes, hydrolysates of alkoxysilanes, and polymers of hydrolysates of alkoxysilanes.

14. The liquid composition according to claim 13, wherein the molar ratio of copper atoms to silicon atoms is 0.1 to 1.

15. The liquid composition according to claim 13 or 14, wherein the molar ratio of phosphorus atoms to silicon atoms is 0.15 to 1.

5.

16. The liquid composition according to any one of claims 13 to 15, wherein the alkoxysilane comprises a primary alkoxysilane that does not contain a hydrocarbon group having 10 or more carbon atoms in one molecule, and a secondary alkoxysilane that contains a hydrocarbon group having 10 or more carbon atoms in one molecule.

17. The liquid composition according to claim 16, wherein the molar ratio of the total amount of the content of the second alkoxysilane, the hydrolysate of the second alkoxysilane converted to the amount of the second alkoxysilane, and the polymer of the hydrolysate of the second alkoxysilane converted to the amount of the second alkoxysilane, to the content of copper atoms is 0.3 to 4.

18. The liquid composition according to claim 16 or 17, wherein the molar ratio of the total amount of the first alkoxysilane, the total amount of the first alkoxysilane, and the total amount of the first alkoxysilane, with respect to the total amount of the second alkoxysilane, the second alkoxysilane, and the first alkoxysilane, with respect to the total amount of the first alkoxysilane, the first alkoxysilane, and the first alkoxysilane, with respect to the second alkoxysilane, is 0.5 to 2.

19. The liquid composition according to any one of claims 11 to 18, wherein the liquid composition is capable of forming a light diffuser having the light diffusing layer, and the total transmitted light for light in the wavelength range of 300 nm to 1200 nm incident on the light diffuser at an incident angle of 0° has a first transmission spectrum, and the first transmission spectrum satisfies the following requirements (i) and (ii): (i) the average transmittance in the wavelength range of 450 nm to 600 nm is 50% or more; (ii) the maximum transmittance in the wavelength range of 800 nm to 1000 nm is 15% or less.

20. The liquid composition according to claim 19, wherein the first transmission spectrum satisfies the following requirement (iii): (iii) The ratio of the maximum transmittance in the wavelength range of 800 nm to 1000 nm to the maximum transmittance in the wavelength range of 450 nm to 650 nm is 0.2 or less.

21. The liquid composition according to claim 19 or 20, wherein the first transmission spectrum has a full width at half maximum of 200 nm to 380 nm.

22. An ambient light sensor comprising a light diffuser according to any one of claims 1 to 10, and a photodetector that receives light transmitted through the light diffuser.

23. An electronic device comprising: a display; an ambient light sensor as described in claim 22; and a control device that adjusts the brightness of the display according to the output of the ambient light sensor.

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